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Sample records for boron 11 reactions

  1. 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.)

  2. Highly-focused boron implantation in diamond and imaging using the nuclear reaction {sup 11}B(p, α){sup 8}Be

    Energy Technology Data Exchange (ETDEWEB)

    Ynsa, M.D., E-mail: m.ynsa@uam.es [Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Física Aplicada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Ramos, M.A. [Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Física de la Materia Condensada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Skukan, N. [Laboratory for Ion Beam Interactions, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb (Croatia); Torres-Costa, V. [Centro de Micro-Análisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Departamento de Física Aplicada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Jakšić, M. [Laboratory for Ion Beam Interactions, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb (Croatia)

    2015-04-01

    Diamond is an especially attractive material because of its gemological value as well as its unique mechanical, chemical and physical properties. One of these properties is that boron-doped diamond is an electrically p-type semiconducting material at practically any boron concentration. This property makes it possible to use diamonds for multiple industrial and technological applications. Boron can be incorporated into pure diamond by different techniques including ion implantation. Although typical energies used to dope diamond by ion implantation are about 100 keV, implantations have also been performed with energies above MeV. In this work CMAM microbeam setup has been used to demonstrate capability to implant boron with high energies. An 8 MeV boron beam with a size of about 5 × 3 μm{sup 2} and a beam current higher than 500 pA has been employed while controlling the beam position and fluence at all irradiated areas. The subsequent mapping of the implanted boron in diamond has been obtained using the strong and broad nuclear reaction {sup 11}B(p, α){sup 8}Be at E{sub p} = 660 keV. This reaction has a high Q-value (8.59 MeV for α{sub 0} and 5.68 MeV for α{sub 1}) and thus is almost interference-free. The sensitivity of the technique is studied in this work.

  3. High sensitivity boron quantification in bulk silicon using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction

    Energy Technology Data Exchange (ETDEWEB)

    Moro, Marcos V.; Silva, Tiago F. da; Added, Nemitala; Rizutto, Marcia A.; Tabacniks, Manfredo H. [Instituto de Fisica da Universidade de Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, SP (Brazil); Neira, John B.; Neto, Joao B. F. [Institute of Research Tecnology, Cidade Universitaria, SP, 05508-091 (Brazil)

    2013-05-06

    There is a great need to quantify sub-ppm levels of boron in bulk silicon. There are several methods to analyze B in Si: Nuclear Reaction Analysis using the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be reaction exhibits a quantification limit of some hundreds ppm of B in Si. Heavy Ion Elastic Recoil Detection Analysis offers a detection limit of 5 to 10 at. ppm. Secondary Ion Mass Spectrometry is the method of choice of the semiconductor industry for the analysis of B in Si. This work verifies the use of NRA to quantify B in Si, and the corresponding detection limits. Proton beam with 1.6 up to 2.6 MeV was used to obtain the cross-section of the {sup 11}B(p,{alpha}{sub 0}){sup 8}Be nuclear reaction at 170 Degree-Sign scattering angle. The results show good agreementwith literature indicating that the quantification of boron in silicon can be achieved at 100 ppm level (high sensitivity) at LAMFI-IFUSP with about 16% uncertainty. Increasing the detection solid angle and the collected beam charge, can reduce the detection limit to less than 100 ppm meeting present technological needs.

  4. 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

  5. Indirect Measurements for (p,α) Reactions Involving Boron Isotopes

    International Nuclear Information System (INIS)

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

    2008-01-01

    Light elements lithium, beryllium and boron (LiBeB) were used in the last years as 'possible probe' for a deeper understanding of some extra-mixing phenomena occurring in young Main-Sequence stars. They are mainly destroyed by (p,α) reactions and cross section measurements for such channels are then needed. The Trojan Horse Method (THM) allows one to extract the astrophysical S(E)-factor without the experience of tunneling through the Coulomb barrier. In this work a resume of the recent results about the 11 B(p,α 0 ) 8 Be and 10 B(p,α) 7 Be reactions is shown

  6. SU-F-T-140: Assessment of the Proton Boron Fusion Reaction for Practical Radiation Therapy Applications Using MCNP6

    Energy Technology Data Exchange (ETDEWEB)

    Adam, D; Bednarz, B [University of Wisconsin, Madison, WI (United States)

    2016-06-15

    Purpose: The proton boron fusion reaction is a reaction that describes the creation of three alpha particles as the result of the interaction of a proton incident upon a 11B target. Theoretically, the proton boron fusion reaction is a desirable reaction for radiation therapy applications in that, with the appropriate boron delivery agent, it could potentially combine the localized dose delivery protons exhibit (Bragg peak) and the local deposition of high LET alpha particles in cancerous sites. Previous efforts have shown significant dose enhancement using the proton boron fusion reaction; the overarching purpose of this work is an attempt to validate previous Monte Carlo results of the proton boron fusion reaction. Methods: The proton boron fusion reaction, 11B(p, 3α), is investigated using MCNP6 to assess the viability for potential use in radiation therapy. Simple simulations of a proton pencil beam incident upon both a water phantom and a water phantom with an axial region containing 100ppm boron were modeled using MCNP6 in order to determine the extent of the impact boron had upon the calculated energy deposition. Results: The maximum dose increase calculated was 0.026% for the incident 250 MeV proton beam scenario. The MCNP simulations performed demonstrated that the proton boron fusion reaction rate at clinically relevant boron concentrations was too small in order to have any measurable impact on the absorbed dose. Conclusion: For all MCNP6 simulations conducted, the increase of absorbed dose of a simple water phantom due to the 11B(p, 3α) reaction was found to be inconsequential. In addition, it was determined that there are no good evaluations of the 11B(p, 3α) reaction for use in MCNPX/6 and further work should be conducted in cross section evaluations in order to definitively evaluate the feasibility of the proton boron fusion reaction for use in radiation therapy applications.

  7. 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

  8. Investigation into boron reaction with titanium at extreme temperature gradients

    International Nuclear Information System (INIS)

    Korchagin, M.A.; Gusenko, S.N.; Aleksandrov, V.V.; Neronov, V.A.

    1981-01-01

    The mechanism of self-propagation high-temperature synthesis of titanium boride is studied using the translucent electron microscopy. Titanium interaction with boron film (approximately 1000 A thick) starts with the metal partial melting. A twozone layer of the reaction products, separating the reagents, is formed. In the zone adjacent to B, Ti 3 B 4 and fusible liquid phases are present. The second zone consists of TiB. The subsequent interaction is realized by Means of the dissolving and absorption by titanium of the layer of products during its continuous increase in boron. TiB 2 formation takes place at subsequent stages of interaction inside Ti liquid particles during their saturation by boron from the products absorbed [ru

  9. The vapour phase deposition of boron on titanium by the reaction between gaseous boron trichloride and titanium metal. Final report

    International Nuclear Information System (INIS)

    Cameron, D.J.; Shelton, R.A.J.

    1965-03-01

    The reaction, between boron trichloride vapour and titanium has been investigated in the temperature range 200 - 1350 deg. C. It has been found that an initial reaction leads to the formation of titanium tetrachloride and the deposition of boron on titanium, but that except for reactions between 900 and 1000 deg. C, the system is complicated by the formation of lower titanium chlorides due to secondary reactions between the titanium and titanium tetrachloride

  10. Defect and dopant depth profiles in boron-implanted silicon studied with channeling and nuclear reaction analysis

    NARCIS (Netherlands)

    Vos, M.; Boerma, D.O.; Smulders, P.J.M.; Oosterhoff, S.

    1986-01-01

    Single crystals of silicon were implanted at RT with 1 MeV boron ions to a dose of 1 × 1015 ions/cm2. The depth profile of the boron was measured using the 2060-keV resonance of the 11B(α, n)14N nuclear reaction. The distribution of the lattice disorder as a function of depth was determined from

  11. 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.)

  12. From Urey To The Ocean's Glacial Ph: News From The Boron-11 Paleo-acidimetry.

    Science.gov (United States)

    Zeebe, R. E.; Wolf-Gladrow, D. A.; Bijma, J.

    Boron paleo-acidimetry is based on the stable boron isotope composition of foraminiferal shells which has been shown to be a function of seawater pH. It is cur- rently one of the most promising paleo-carbonate chemistry proxies. One important parameter of the proxy is the equilibrium fractionation between the dissolved boron species B(OH)3 and B(OH)- which was calculated to be 19 per mil at 25C by Kak- 4 ihana and Kotaka (1977), based on Urey's theory. The calculated equilibrium frac- tionation, however, depends on the vibrational frequencies of the molecules for which different values have been reported in the literature. We have recalculated the equilib- rium fractionation and find that it may be distinctly different from 19 per mil (this is the bad news). The good news is that - theoretically - the use of 11B as a paleo-pH indicator is not compromised through vital effects in planktonic foraminifera. We de- rive this conclusion by the use of a diffusion-reaction model that calculates pH profiles and 11B values in the vicinity of a foraminifer.

  13. Boron

    Science.gov (United States)

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

  14. The water decomposition reactions on boron-doped diamond electrodes

    International Nuclear Information System (INIS)

    Suffredini, Hugo B.; Machado, Sergio A.S; Avaca, Luis A.

    2004-01-01

    The electrochemical processes occurring at both edges of the wide electrochemical window of the boron doped diamond (BDD) electrode were studied by polarization curves experiments to evaluate the apparent energy of activation for the rate determining step in each reaction. It was found that the hydrogen evolution reaction occurs by a Volmer-Heyrovsky mechanism with the first step being the RDS. Moreover, the apparent energy of activation calculated from the Tafel plots presented a value as high as 150 kJ mol -1 , indicating the formation of the M-H intermediate that is characteristic for the Volmer step. On the other hand, the apparent energy of activation for the oxygen evolution reaction was found to be 106 kJ mol -1 suggesting that the RDS in this mechanism is the initial adsorption step. In this way, it was demonstrated that the interaction between water molecules and the electrode surface is strongly inhibited on BDD thus justifying the extended potential window observed for this material. (author)

  15. The water decomposition reactions on boron-doped diamond electrodes

    Directory of Open Access Journals (Sweden)

    Suffredini Hugo B

    2004-01-01

    Full Text Available The electrochemical processes occurring at both edges of the wide electrochemical window of the boron doped diamond (BDD electrode were studied by polarization curves experiments to evaluate the apparent energy of activation for the rate determining step in each reaction. It was found that the hydrogen evolution reaction occurs by a Volmer-Heyrovsky mechanism with the first step being the RDS. Moreover, the apparent energy of activation calculated from the Tafel plots presented a value as high as 150 kJ mol-1, indicating the formation of the M-H intermediate that is characteristic for the Volmer step. On the other hand, the apparent energy of activation for the oxygen evolution reaction was found to be 106 kJ mol-1 suggesting that the RDS in this mechanism is the initial adsorption step. In this way, it was demonstrated that the interaction between water molecules and the electrode surface is strongly inhibited on BDD thus justifying the extended potential window observed for this material.

  16. Dependence of reaction pressure on deposition and properties of boron-doped freestanding diamond films

    International Nuclear Information System (INIS)

    Li Liuan; Li Hongdong; Lue Xianyi; Cheng Shaoheng; Wang Qiliang; Ren Shiyuan; Liu Junwei; Zou Guangtian

    2010-01-01

    In this paper, we investigate the reaction pressure-dependent growth and properties of boron-doped freestanding diamond films, synthesized by hot filament chemical vapor deposition (HFCVD) at different boron-doping levels. With the decrease in pressure, the growth feature of the films varies from mixed [1 1 1] and [1 1 0] to dominated [1 1 1] texture. The low reaction pressure, as well as high boron-doping level, results in the increase (decrease) of carrier concentration (resistivity). The high concentration of atomic hydrogen in the ambient and preferable [1 1 1] growth, due to the low reaction pressure, is available for the enhancement of boron doping. The estimated residual stress increases with increase in the introducing boron level.

  17. Three New Offset {delta}{sup 11}B Isotope Reference Materials for Environmental Boron Isotope Studies

    Energy Technology Data Exchange (ETDEWEB)

    Rosner, M. [BAM Federal Institute for Materials Research and Testing, Berlin (Germany); IsoAnalysis UG, Berlin (Germany); Vogl, J. [BAM Federal Institute for Materials Research and Testing, Berlin (Germany)

    2013-07-15

    The isotopic composition of boron is a well established tool in various areas of science and industry. Boron isotope compositions are typically reported as {delta}{sup 11}B values which indicate the isotopic difference of a sample relative to the isotope reference material NIST SRM 951. A significant drawback of all of the available boron isotope reference materials is that none of them covers a natural boron isotope composition apart from NIST SRM 951. To fill this gap of required {delta}{sup 11}B reference materials three new solution boric acid reference materials were produced, which cover 60 per mille of the natural boron isotope variation (-20 to 40 per mille {delta}{sup 11}B) of about 100 per mille . The new reference materials are certified for their {delta}{sup 11}B values and are commercially available through European Reference Materials (http://www.erm-crm.org). The newly produced and certified boron isotope reference materials will allow straightforward method validation and quality control of boron isotope data. (author)

  18. Electron screening effects in (p,α) reactions induced on boron isotopes studied via the Trojan Horse Method

    International Nuclear Information System (INIS)

    Lamia, L; Spitaleri, C; Cherubini, S; Gulino, M; Puglia, S M R; Rapisarda, G G; Romano, S; Sergi, M L; Carlin, N; Gameiro Munhoz, M; Gimenez Del Santo, M; Kiss, G G; Somorjai, E; Kroha, V; Kubono, S; La Cognata, M; Pizzone, R G; Li, C; Wen, Qungang; Mukhamedzhanov, A

    2013-01-01

    The Trojan Horse Method is a powerful indirect technique allowing one to measure the bare nucleus S(E)-factor and the electron screening potential for astrophysically relevant reactions without the needs of extrapolations. The case of the (p,α) reactions induced on the two boron isotopes 10,11 B is here discussed in view of the recent Trojan Horse (TH) applications to the quasi-free 10,11 B+ 2 H reactions. The comparison between the TH and the low-energy direct data allowed us to determine the electron screening potential for the 11 B(p,α) reaction, while preliminary results on the 10 B(p,α) reaction have been extracted.

  19. Two-dimensional boron: Lightest catalyst for hydrogen and oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mir, Showkat H. [Centre for Nano Science, Central University of Gujarat, Gandhinagar 382030 (India); Chakraborty, Sudip, E-mail: sudiphys@gmail.com, E-mail: prakash.jha@cug.ac.in; Wärnå, John [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Uppsala 75120 (Sweden); Jha, Prakash C., E-mail: sudiphys@gmail.com, E-mail: prakash.jha@cug.ac.in [School of Applied Material Sciences, Central University of Gujarat, Gandhinagar 382030 (India); Soni, Himadri [Lehrstuhl für Theoretische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen (Germany); Jha, Prafulla K. [Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390 002 (India); Ahuja, Rajeev [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Uppsala 75120 (Sweden); Department of Materials and Engineering, Royal Institute of Technology (KTH), 10044 Stockholm (Sweden)

    2016-08-01

    The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) have been envisaged on a two-dimensional (2D) boron sheet through electronic structure calculations based on a density functional theory framework. To date, boron sheets are the lightest 2D material and, therefore, exploring the catalytic activity of such a monolayer system would be quite intuitive both from fundamental and application perspectives. We have functionalized the boron sheet (BS) with different elemental dopants like carbon, nitrogen, phosphorous, sulphur, and lithium and determined the adsorption energy for each case while hydrogen and oxygen are on top of the doping site of the boron sheet. The free energy calculated from the individual adsorption energy for each functionalized BS subsequently guides us to predict which case of functionalization serves better for the HER or the OER.

  20. Electron spectroscopic imaging of antigens by reaction with boronated antibodies.

    Science.gov (United States)

    Qualmann, B; Kessels, M M; Klobasa, F; Jungblut, P W; Sierralta, W D

    1996-07-01

    Two small homogeneous markers for electron spectroscopic imaging (ESI) containing eight dodecaborane cages linked to a poly-alpha, epsilon-L-lysine dendrimer were synthesized; one of these was made water soluble by the attachment of a polyether. The markers were coupled to the sulfhydryl group of (monovalent) antibody fragments (Fab') by a homobifunctional cross-linker. While the coupling ratios of the poorly water-soluble compound did not exceed 20%, the polyether-containing variant reacted quantitatively. Its suitability for immunolabelling was tested in a study of the mechanism of the transcellular transport of an administered heterologous protein (bovine serum albumin, BSA) through ileal enterocytes of newborn piglets by endocytotic vesicles in comparison to conventional immunogold reagents. The post-embedding technique was employed. The boronated Fab' gave rise to considerably higher tagging frequencies than seen with immunogold, as could be expected from its form- and size-related physical advantages and the dense packing of BSA in the vesicles. The new probe, carrying the antigen-combining cleft at one end and the boron clusters at the opposite end of the oval-shaped conjugate, add to the potential of ESI-based immunocytochemistry.

  1. BOREX: Solar neutrino experiment via weak neutral and charged currents in boron-11

    International Nuclear Information System (INIS)

    Kovacs, T.; Mitchell, J.W.; Raghavan, P.

    1989-01-01

    Borex, and experiment to observe solar neutrinos using boron loaded liquid scintillation techniques, is being developed for operation at the Gran Sasso underground laboratory. It aims to observe the spectrum of electron type 8 B solar neutrinos via charged current inverse β-decay of 11 B and the total flux solar neutrinos regardless of flavor by excitation of 11 B via the weak neutral current. 14 refs

  2. Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

    Energy Technology Data Exchange (ETDEWEB)

    Muramatsu, Y.; Grush, M.; Callcott, T.A. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called {open_quotes}super diamond,{close_quotes} and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods.

  3. Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

    International Nuclear Information System (INIS)

    Muramatsu, Y.; Grush, M.; Callcott, T.A.

    1997-01-01

    Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called open-quotes super diamond,close quotes and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods

  4. Effect of reaction time on the characteristics of catalytically grown boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Norani Muti, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Ahmad, Pervaiz, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Saheed, Mohamed Shuaib Mohamed, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my; Burhanudin, Zainal Arif, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: pervaiz-pas@yahoo.com, E-mail: shuaib-penang@yahoo.com, E-mail: zainabh@petronas.com.my [Center of Innovative Nanostructures and Nanodevices (COINN), Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750, Tronoh, Perak (Malaysia)

    2014-10-24

    The paper reports on the growth of boron nitride nanotube (BNNTs) on Si substrate by catalytic chemical vapor deposition technique and the effect of reaction time and temperature on the size and purity were investigated. Scanning electron microscopy image revealed the bamboo-like BNNTs of multiwalled type with interlayer spacing of 0.34 nm. EDX analysis described the presence of a small percentage of Mg in the sample, indicating the combination of base-tip growth model for the sample synthesized at 1200°C. The reaction time has an effect of extending the length of the BNNTs until the catalyst is oxidized or covered by growth precursor.

  5. Effect of reaction time on the characteristics of catalytically grown boron nitride nanotubes

    International Nuclear Information System (INIS)

    Mohamed, Norani Muti; Ahmad, Pervaiz; Saheed, Mohamed Shuaib Mohamed; Burhanudin, Zainal Arif

    2014-01-01

    The paper reports on the growth of boron nitride nanotube (BNNTs) on Si substrate by catalytic chemical vapor deposition technique and the effect of reaction time and temperature on the size and purity were investigated. Scanning electron microscopy image revealed the bamboo-like BNNTs of multiwalled type with interlayer spacing of 0.34 nm. EDX analysis described the presence of a small percentage of Mg in the sample, indicating the combination of base-tip growth model for the sample synthesized at 1200°C. The reaction time has an effect of extending the length of the BNNTs until the catalyst is oxidized or covered by growth precursor

  6. Boron-Based Catalysts for C-C Bond-Formation Reactions.

    Science.gov (United States)

    Rao, Bin; Kinjo, Rei

    2018-05-02

    Because the construction of the C-C bond is one of the most significant reactions in organic chemistry, the development of an efficient strategy has attracted much attention throughout the synthetic community. Among various protocols to form C-C bonds, organoboron compounds are not just limited to stoichiometric reagents, but have also made great achievements as catalysts because of the easy modification of the electronic and steric impacts on the boron center. This review presents recent developments of boron-based catalysts applied in the field of C-C bond-formation reactions, which are classified into four kinds on the basis of the type of boron catalyst: 1) highly Lewis acidic borane, B(C 6 F 5 ) 3 ; 2) organoboron acids, RB(OH) 2 , and their ester derivatives; 3) borenium ions, (R 2 BL)X; and 4) other miscellaneous kinds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2018-04-01

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

  8. Particle track etch method for analysis of boron in silicon using 10B(n,α)7Li reaction

    International Nuclear Information System (INIS)

    Chakarvarti, S.K.; Nagpaul, K.K.

    1980-01-01

    Boron bulk doped p-type (111) silicon thin wafers of different resistivities (1 to 100 ohm-cm +- 20%) have been analysed for boron using cellulose nitrate-Daicel and red dyed LR-115 type II films as detectors of alpha particles from 10 B(n,α) 7 Li reaction. The two detectors measure the same value of boron (approximately 0.1 ppm) in 1 ohm-cm silicon samples and agree closely with the four-point probe electrical resistivity measurement results whereas large discrepancies are observed in case of samples with resistivity > 1 ohm-cm (B concentration 1 ohm-cm. (author)

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

    International Nuclear Information System (INIS)

    Portu, A.; Galván, V.; González, S.J.; Thorp, S.; Santa Cruz, G.; Saint Martin, G.; Blostein, J.J.

    2013-01-01

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

  10. Production of 11Li in the (11B,11Li) reaction on 232Th

    International Nuclear Information System (INIS)

    Scott, D.K.; Buenerd, M.; Hendrie, D.L.; KeKelis, G.; Mahoney, J.; Menchaca-Rocha, A.; Olmer, C.

    1975-01-01

    Production of the neutron-rich nucleus 11 Li in the bombardment of 232 Th by 11 B at 114 MeV suggests that multinucleon transfer reactions induced by neutron excess heavy ions on heavy targets present a feasible method of measuring the mass excess of exotic light nuclei in the limit of stability

  11. Quinine-Promoted, Enantioselective Boron-Tethered Diels-Alder Reaction by Anomeric Control of Transition State Conformation.

    Science.gov (United States)

    Scholl, Katie; Dillashaw, John; Timpy, Evan; Lam, Yu-Hong; DeRatt, Lindsey; Benton, Tyler R; Powell, Jacqueline P; Houk, Kendall N; Morgan, Jeremy B

    2018-05-01

    Diels-Alder reactions of tethered vinyl-metal species offer the opportunity to fashion highly functionalized diol intermediates for synthesis. We have developed the first enantioselective boron-tethered Diels-Alder reaction using quinine as a chiral promoter. Quinine recovery, enantioselectivity enhancement, and manipulation of the cyclohexene core are also investigated. DFT modeling calculations confirm the role of quinine as a bidentate ligand enhancing reaction rates. The enantioselectivity of the cycloaddition is proposed to originate from a boron-centered anomeric effect.

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

    International Nuclear Information System (INIS)

    Rath, N.P.; Fehlner, T.P.

    1988-01-01

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

  13. Activation barriers for series of exothermic homologous reactions. V. Boron group diatomic species reactions

    Science.gov (United States)

    Blue, Alan S.; Belyung, David P.; Fontijn, Arthur

    1997-09-01

    Semiempirical configuration interaction (SECI) theory is used to predict activation barriers E, as defined by k(T)=ATn exp(-E/RT). Previously SECI has been applied to homologous series of oxidation reactions of s1, s2, and s2p1 metal atoms. Here it is extended to oxidation reactions of diatomic molecules containing one s2p1 atom. E values are calculated for the reactions of BH, BF, BCl, AlF, AlCl, AlBr, GaF, GaI, InCl, InBr, InI, TlF, TlCl, TlBr, and TlI with O2, CO2, SO2, or N2O. These values correlate with the sums of the ionization potentials and Σ-Π promotion energies of the former minus the electron affinities of the latter. In the earlier work n was chosen somewhat arbitrarily, which affected the absolute values of E. Here it is shown that examination of available experimental and theoretical results allows determination of the best values of n. Using this approach yields n=1.9 for the present series. For the seven reactions which have been studied experimentally, the average deviation of the SECI activation barrier prediction from experiment is 4.0 kJ mol-1. Energy barriers are calculated for another 52 reactions.

  14. Chirality Relay in 2,2'-Substituted 1,1'-Binaphthyl: Access to Propeller Chirality of the Tricoordinate Boron Center.

    Science.gov (United States)

    Wang, Chen; Sun, Zuo-Bang; Xu, Qing-Wen; Zhao, Cui-Hua

    2016-11-14

    It is a challenging issue to achieve propeller chirality for triarylboranes owing to the low transition barrier between the P and M forms of the boron center. Herein, we report a new strategy to achieve propeller chirality of triarylboranes. It was found that the chirality relay from axially chiral 1,1'-binaphthyl to propeller chirality of the trivalent boron center can be realized when a Me 2 N and a Mes 2 B group (Mes=mesityl) are introduced at the 2,2'-positions of the 1,1'-binaphthyl skeleton (BN-BNaph) owing to the strong π-π interaction between the Me 2 N-bonded naphthyl ring and the phenyl ring of one adjacent Mes group, which not only exerts great steric hindrance on the rotation of the two Mes groups but also gives unequal stability to the two configurations of the boron center for a given configuration of the binaphthyl moiety. The stereostructures of the boron center were fully characterized through 1 H NMR spectroscopy, X-ray crystal analyses, and theoretical calculations. Detailed comparisons with the analog BN-Ph-BNaph, in which the Mes 2 B group is separated from 1,1'-binaphthyl by a para-phenylene spacer, confirmed the essential role of π-π interaction for the successful chirality relay in BN-BNaph. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. 1,5-Asymmetric induction in the boron-mediated aldol reaction of β-oxygenated methyl ketones

    International Nuclear Information System (INIS)

    Dias, Luiz C.

    2007-01-01

    High levels of substrate-based 1,5-stereo induction are obtained in the boron-mediated aldol reactions of β-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At present, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed. (author)

  16. A Simulation Study for Radiation Treatment Planning Based on the Atomic Physics of the Proton-Boron Fusion Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sunmi; Yoon, Do-Kun; Shin, Han-Back; Jung, Joo-Young; Kim, Moo-Sub; Kim, Kyeong-Hyeon; Jang, Hong-Seok; Suh, Tae Suk [the Catholic University of Korea, Seoul (Korea, Republic of)

    2017-03-15

    The purpose of this research is to demonstrate, based on a Monte Carlo simulation code, the procedure of radiation treatment planning for proton-boron fusion therapy (PBFT). A discrete proton beam (60 - 120 MeV) relevant to the Bragg peak was simulated using a Monte Carlo particle extended (MCNPX, Ver. 2.6.0, National Laboratory, Los Alamos NM, USA) simulation code. After computed tomography (CT) scanning of a virtual water phantom including air cavities, the acquired CT images were converted using the simulation source code. We set the boron uptake regions (BURs) in the simulated water phantom to achieve the proton-boron fusion reaction. Proton sources irradiated the BUR, in the phantom. The acquired dose maps were overlapped with the original CT image of the phantom to analyze the dose volume histogram (DVH). We successfully confirmed amplifications of the proton doses (average: 130%) at the target regions. From the DVH result for each simulation, we acquired a relatively accurate dose map for the treatment. A simulation was conducted to characterize the dose distribution and verify the feasibility of proton boron fusion therapy (PBFT). We observed a variation in proton range and developed a tumor targeting technique for treatment that was more accurate and powerful than both conventional proton therapy and boron-neutron capture therapy.

  17. Porous boron doped diamonds as metal-free catalysts for the oxygen reduction reaction in alkaline solution

    Science.gov (United States)

    Suo, Ni; Huang, Hao; Wu, Aimin; Cao, Guozhong; Hou, Xiaoduo; Zhang, Guifeng

    2018-05-01

    Porous boron doped diamonds (BDDs) were obtained on foam nickel substrates with a porosity of 80%, 85%, 90% and 95% respectively by hot filament chemical vapor deposition (HFCVD) technology. Scanning electron microscopy (SEM) reveals that uniform and compact BDDs with a cauliflower-like morphology have covered the overall frame of the foam nickel substrates. Raman spectroscopy shows that the BDDs have a poor crystallinity due to heavily doping boron. X-ray photoelectron spectroscopy (XPS) analysis effectively demonstrates that boron atoms can be successfully incorporated into the crystal lattice of diamonds. Electrochemical measurements indicate that the oxygen reduction potential is unaffected by the specific surface area (SSA), and both the onset potential and the limiting diffusion current density are enhanced with increasing SSA. It is also found that the durability and methanol tolerance of the boron doped diamond catalysts are attenuated as the increasing of SSA. The SSA of the catalyst is directly proportional to the oxygen reduction activity and inversely to the durability and methanol resistance. These results provide a reference to the application of porous boron doped diamonds as potential cathodic catalysts for the oxygen reduction reaction in alkaline solution by adjusting the SSA.

  18. Structure and reactivity of boron-ate complexes derived from primary and secondary boronic esters.

    Science.gov (United States)

    Feeney, Kathryn; Berionni, Guillaume; Mayr, Herbert; Aggarwal, Varinder K

    2015-06-05

    Boron-ate complexes derived from primary and secondary boronic esters and aryllithiums have been isolated, and the kinetics of their reactions with carbenium ions studied. The second-order rate constants have been used to derive nucleophilicity parameters for the boron-ate complexes, revealing that nucleophilicity increased with (i) electron-donating aromatics on boron, (ii) neopentyl glycol over pinacol boronic esters, and (iii) 12-crown-4 ether.

  19. 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

  20. Simultaneous Nuclear Reaction Analysis of Boron and Phosphorus in Thin Borophosphosilicate Glass Films Using (α,p) Reactions

    International Nuclear Information System (INIS)

    Walsh, D.S.; Doyle, B.L.

    1999-01-01

    A method combining (α,p) NRA and ellipsometry has been developed for measuring the Boron and Phosphorus content of borophosphosilicate glass (BPSG) used for interlevel dielectrics in integrated circuits. Yields from the 31 P(α,p 0 ) 34 S (Q = 0.63 MeV) and 10 B(α,p 0 ) 13 C (Q = 4.06 MeV) reactions are coupled with ellipsometry thickness measurements to calculate the average atomic percent of B and P in the film. Due to the relatively low Q value of the 31 P(α,p 0 ) 34 S reaction and the thickness range of the glass films (le 1.2 micrometers) they analyze, fairly high energy alpha particles, and Mylar range foils on the detector are required. Alpha energy, detector angle and range foil thickness were determined by reaction yields and the need to separate the yield peaks of interest from competing (α,p) reactions and backscattered alphas. They have determined that 6.0 MeV incident alphas with a detector angle of 135degree and about 100 micrometers of Mylar range foil are optimum for the system. The yield for the 10 B(α,p 0 ) 13 C reaction is quite constant in the energy range of interest (approximately 5.8 to 6 MeV) but the yield for the 31 P(α,p 0 ) 34 S is not. Consequently, a simple conversion from standard BPSG reference samples (independently quantified by ICP mass spectrometry) is adequate to calculate a film's %B content. The %P calculation is more complex, involving a three-dimensional fit of the P yield data and measured film thickness to the film %P content. This fit is based upon yield data from a matrix of standard film samples. The technique is sensitive to 0.1% with an accuracy of ±3 to ±10% depending on the sample. This measurement method is used routinely at Sandia National Laboratories in support of their fabrication process lines

  1. Reaction between peroxynitrite and boronates: EPR spin-trapping, HPLC analyses, and quantum mechanical study of the free radical pathway

    Science.gov (United States)

    Sikora, Adam; Zielonka, Jacek; Lopez, Marcos; Dybala-Defratyka, Agnieszka; Joseph, Joy; Marcinek, Andrzej; Kalyanaraman, Balaraman

    2013-01-01

    Recently we showed that peroxynitrite (ONOO−) reacts directly and rapidly with aromatic and aliphatic boronic acids (k ≈ 106 M−1s−1). Product analyses and substrate consumption data indicated that ONOO− reacts stoichiometrically with boronates, yielding the corresponding phenols as the major product (~85–90%), and the remaining products (10–15%) were proposed to originate from free radical intermediates (phenyl and phenoxyl radicals). Here we investigated in detail the minor, free radical pathway of boronate reaction with ONOO−. The electron paramagnetic resonance (EPR) spin-trapping technique was used to characterize the free radical intermediates formed from the reaction between boronates and ONOO−. Using 2-methyl-2-nitrosopropane (MNP) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO) spin traps, phenyl radicals were trapped and detected. Although phenoxyl radicals were not detected, the positive effects of molecular oxygen, and inhibitory effects of hydrogen atom donors (acetonitrile, and 2-propanol) and general radical scavengers (GSH, NADH, ascorbic acid and tyrosine) on the formation of phenoxyl radical-derived nitrated product, suggest that phenoxyl radical was formed as the secondary species. We propose that the initial step of the reaction involves the addition of ONOO− to the boron atom in boronates. The anionic intermediate undergoes both heterolytic (major pathway) and homolytic (minor pathway) cleavage of the peroxy (O-O) bond to form phenol and nitrite as a major product (via a non-radical mechanism), or a radical pair PhB(OH)2O•−…•NO2 as a minor product. It is conceivable that phenyl radicals are formed by the fragmentation of PhB(OH)2O•− radical anion. According to the DFT quantum mechanical calculations, the energy barrier for the dissociation of PhB(OH)2O•− radical anion to form phenyl radicals is only a few kcal/mol, suggesting rapid and spontaneous fragmentation of PhB(OH)2O•− radical anion

  2. Boron-dependency of molybdenum boride electrocatalysts for the hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyounmyung; Encinas, Andrew; Fokwa, Boniface P.T. [Department of Chemistry, University of California, Riverside, CA (United States); Department of Chemical and Environmental Engineering, University of California, Riverside, CA (United States); Scheifers, Jan P.; Zhang, Yuemei [Department of Chemistry, University of California, Riverside, CA (United States)

    2017-05-08

    Molybdenum-based materials have been considered as alternative catalysts to noble metals, such as platinum, for the hydrogen evolution reaction (HER). We have synthesized four binary bulk molybdenum borides Mo{sub 2}B, α-MoB, β-MoB, and MoB{sub 2} by arc-melting. All four phases were tested for their electrocatalytic activity (linear sweep voltammetry) and stability (cyclic voltammetry) with respect to the HER in acidic conditions. Three of these phases were studied for their HER activity and by X-ray photoelectron spectroscopy (XPS) for the first time; MoB{sub 2} and β-MoB show excellent activity in the same range as the recently reported α-MoB and β-Mo{sub 2}C phases, while the molybdenum richest phase Mo{sub 2}B show significantly lower HER activity, indicating a strong boron-dependency of these borides for the HER. In addition, MoB{sub 2} and β-MoB show long-term cycle stability in acidic solution. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Boron-dependency of molybdenum boride electrocatalysts for the hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Park, Hyounmyung; Encinas, Andrew; Fokwa, Boniface P.T.; Scheifers, Jan P.; Zhang, Yuemei

    2017-01-01

    Molybdenum-based materials have been considered as alternative catalysts to noble metals, such as platinum, for the hydrogen evolution reaction (HER). We have synthesized four binary bulk molybdenum borides Mo_2B, α-MoB, β-MoB, and MoB_2 by arc-melting. All four phases were tested for their electrocatalytic activity (linear sweep voltammetry) and stability (cyclic voltammetry) with respect to the HER in acidic conditions. Three of these phases were studied for their HER activity and by X-ray photoelectron spectroscopy (XPS) for the first time; MoB_2 and β-MoB show excellent activity in the same range as the recently reported α-MoB and β-Mo_2C phases, while the molybdenum richest phase Mo_2B show significantly lower HER activity, indicating a strong boron-dependency of these borides for the HER. In addition, MoB_2 and β-MoB show long-term cycle stability in acidic solution. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. A Monte Carlo simulation of boron neutron capture reactions in cells - Microdosimetric aspects

    International Nuclear Information System (INIS)

    Nguyen, T.; Brownell, G.L.

    1992-01-01

    The neutron capture reaction in boron ( 10 B(n,α) 7 Li) generates two short-range particles with high LET. The effect of neutron capture therapy (NCT) depends on the microscopic distribution of 10 B atoms in target cells. Due to the short ranges of the charged particles, an intracellular localization of 10 B in one region may produce a different effect to the cell than the same concentration of 10 B localized in other regions. Monte Carlo calculations of the energy deposition produced by 10 B disintegrations were performed to compare the effectiveness of 10 B localized in five separate source regions of the modeled cells: nucleus, nuclear membrane, cytoplasm, plasma membrane, and extracellular space. Two regions (nucleus and the whole cell) were independently considered the sensitive targets for the radiation therapy. An effectiveness factor (EF), defined by combining the radiation dose resulting from the 10 B disintegrations with the distribution of 10 B in a cell population, was used to determine the effectiveness of 10 B(n,α) 7 Li reactions in different source regions. When an RBE and LET relationship was obtained from experimental data, the RBE values of the α and 7 Li radiations originating in different source regions were calculated, taking into account the stochastic nature of the origins of the 10 B disintegrations in these regions. The computations indicate that if the nucleus was the only radiation sensitive region, the nuclear 10 B disintegrations would be most effective for NCT, followed by 10 B disintegrations in the nuclear membrane (48% as effective). 10 B disintegrations in the cytoplasm, cell membrane, and extracellular space were about 10%, 5%, and 2%, respectively, as effective as nuclear 10 B

  5. Mass of 11Li from the 1H(11Li,9Li)3H reaction

    International Nuclear Information System (INIS)

    Roger, T.; Savajols, H.; Mittig, W.; Caamano, M.; Roussel-Chomaz, P.; Tanihata, I.; Alcorta, M.; Bandyopadhyay, D.; Bieri, R.; Buchmann, L.; Davids, B.; Galinski, N.; Howell, D.; Mills, W.; Mythili, S.; Openshaw, R.; Padilla-Rodal, E.; Ruprecht, G.; Sheffer, G.; Shotter, A. C.

    2009-01-01

    The mass of 11 Li has been determined from Q-value measurements of the 1 H( 11 Li, 9 Li) 3 H reaction. The experiment was performed at TRIUMF laboratory with the GANIL active target MAYA. Energy-energy and angle-angle kinematics reconstruction give a Q value of 8.119(22) MeV for the reaction. The derived 11 Li two-neutron separation energy is S 2n =363(22) keV

  6. Synthesis of 5-organo-, 9-organo-, and 9,11-diorgano-nido-7,8-dicarbaundecaborate salts by a cross-combination reaction

    International Nuclear Information System (INIS)

    Zakharkin, L.I.; Ol'shevskaya, V.A.; Petrovskij, P.V.

    2000-01-01

    It has been shown for the first time that salts of 5-iodine and 9,11-diiodine-nido-7,8-dicarbaundecaborates, containing iodine atoms near polyhedron pentagonal surface boron atoms, enter cross-combination reaction with magnesium organic compounds during catalysis by palladium complexes with formation of 5-organo-, 9-organo-, and 9,11-diorgano-nido-7,8-dicarbaundecaborate salts [ru

  7. In-phantom dosimetry using the 13C(d,n)14N reaction for BNCT (boron neutron capture therapy)

    International Nuclear Information System (INIS)

    Burlon, Alejandro; Kreiner, Andres J.; White, S.; Blackburn, B.; Gierga, David; Yanch, Jacquelyn C.

    2000-01-01

    The use of the 13 C(d,n) 14 N reaction at E d =1.5 MeV for accelerator-based boron neutron capture therapy is investigated. The 13 C(d,n) 14 N reaction presents the advantages of carbon as a target material and its large cross section. The deuteron beam was produced by a tandem accelerator at MIT's Laboratory for Accelerator Beam Applications. The resulting neutron spectra were evaluated in terms of RBE-dose rates at different depths inside a water-filled brain phantom using a heavy water moderator and lead reflector assembly. All results were simulated using the code MCNP. (author)

  8. Crossed Molecular Beams Investigations on the Dynamics and Energetics of Elementary Boron Reactions with Unsaturated Hydrocarbons

    National Research Council Canada - National Science Library

    Kaiser, Ralf I

    2006-01-01

    ...). It should be recalled that the AFOSR Grant FA9550-05-1-0124 under which the experiments have been conducted was intended as a starter grant to get the experimental setup complete, the boron source...

  9. Amine and Titanium (IV Chloride, Boron (III Chloride or Zirconium (IV Chloride-Promoted Baylis-Hillman Reactions

    Directory of Open Access Journals (Sweden)

    Shi-Cong Cui

    2001-10-01

    Full Text Available The Baylis-Hillman reactions of various aryl aldehydes with methyl vinyl ketone at temperatures below -20oC using Lewis acids such as titanium (IV chloride, boron (III chloride or zirconium (IV chloride in the presence of a catalytic amount of selected amines used as a Lewis bases afford the chlorinated compounds 1 as the major product in very high yields. Acrylonitrile can also undergo the same reaction to give the corresponding chlorinated product in moderate yield. A plausible reaction mechanism is proposed. However, if the reaction was carried out at room temperature (ca. 20oC, then the Z-configuration of the elimination product 3, derived from 1, was formed as the major product.

  10. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO2

    International Nuclear Information System (INIS)

    Galenda, A.; Crociani, L.; Habra, N. El; Favaro, M.; Natile, M.M.; Rossetto, G.

    2014-01-01

    Highlights: • Boron and/or nitrogen-doped TiO 2 for photocatalytic wastewater treatment. • Methyl red degradation/mineralisation as a function of pH, acids and dopants. • Adsorption time influence on photocatalytic process. • Recovery of worn-out catalyst. - Abstract: Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO 2 -based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV–vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage

  11. Effect of Dissolved Silica on Immobilization of Boron by Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Shoko Nozawa

    2018-02-01

    Full Text Available The effect of silica on the immobilization reaction of boron by magnesium oxide was investigated by laboratory experiments. In the absence of silica, due to dissolution of the magnesium oxide, boron was removed from solutions by the precipitation of multiple magnesium borates. In the presence of silica, magnesium silica hydrate (M-S-H was formed as a secondary mineral, which takes up boron. Here 11B magic-angle spinning nuclear magnetic resonance (MAS-NMR and Fourier transform infrared spectrometer (FT-IR data show that a part of the boron would be incorporated into M-S-H structures by isomorphic substitution of silicon. Another experiment where magnesium oxide and amorphous silica were reacted beforehand and boron was added later showed that the shorter the reaction time of the preceding reaction, the higher the sorption ratio of boron. That is, boron was incorporated into the M-S-H mainly by coprecipitation. The experiments in the study here show that the sorption of boron in the presence of silica is mainly due to the incorporation of boron during the formation of the M-S-H structure, which suggests that boron would not readily leach out, and that stable immobilization of boron can be expected.

  12. Controlling the reaction between boron-containing sealing glass and a lanthanum-containing cathode by adding Nb2O5

    Science.gov (United States)

    Zhao, Dandan; Fang, Lihua; Tang, Dian; Zhang, Teng

    2016-09-01

    In solid oxide fuel cell (SOFC) stacks, the volatile boron species present in the sealing glass often react with the lanthanum-containing cathode, degrading the activity of the cathode (this phenomenon is known as boron poisoning). In this work, we report that this detrimental reaction can be effectively reduced by doping bismuth-containing borosilicate sealing glass-ceramic with a niobium dopant. The addition of Nb2O5 not only condenses the [SiO4] structural units in the glass network, but also promotes the conversion of [BO3] to [BO4]. Moreover, the Nb2O5 dopant enhances the formation of boron-containing phases (Ca3B2O6 and CaB2Si2O8), which significantly reduces the volatility of boron compounds in the sealing glass, suppressing the formation of LaBO3 in the reaction couple between the glass and the cathode. The reported results provide a new approach to solve the problem of boron poisoning.

  13. High temperature synthesis of ceramic composition by directed reaction of molten titanium or zirconium with boron carbide

    International Nuclear Information System (INIS)

    Johnson, W.B.

    1990-01-01

    Alternative methods of producing ceramics and ceramic composites include sintering, hot pressing and more recently hot isostatic pressing (HIP) and self-propagating high temperature synthesis (SHS). Though each of these techniques has its advantages, each suffers from several restrictions as well. Sintering may require long times at high temperatures and for most materials requires sintering aids to get full density. These additives can, and generally do, change (often degrade) the properties of the ceramic. Hot pressing and hot isostatic pressing are convenient methods to quickly prepare samples of some materials to full density, but generally are expensive and may damage some types of reinforcements during densification. This paper focuses on the preparation and processing of composites prepared by the directed reaction of molten titanium or zirconium with boron carbide. Advantages and disadvantages of this approach when compared to traditional methods are discussed, with reference to specific examples. Examples of microstructure are properties of these materials are reported

  14. Contribution to the study of the reaction p + 11B = 3 α by the coincidence method

    International Nuclear Information System (INIS)

    Laugier, J.Ph.

    1969-01-01

    We have studied the production mode of the 3 α system in the reaction p + 11 B = 12 C * = α + 8 Be * ; 8 Be * = α + α. We have got some information for three different effects: the influence of the 8 Be residual nucleus states = sequential decay; the influence of the 12 C compound nucleus states = spin effect; an interference effect. We give a theoretical expression of the different spectra which take into account the observed phenomena. We have taken, as a parameter, the phase shift, between the waves associated with the detected particles, which produce the interference effect. The main characteristics of the experimental devices are : self supporting boron targets; cooled semiconductor detectors; multi-parametric system: for each nuclear event three parameters are recorded: the energies of the detected particles and the time of the detection; Recording system: the information are recorded on a magnetic tape and at the same time treated with an on line CAE 510 computer. The CAE 510 computer is used in delayed time to analyse the experimental data. (author) [fr

  15. Heavy ion collision dynamics of 10,11B+10,11B reactions

    Directory of Open Access Journals (Sweden)

    Singh BirBikram

    2015-01-01

    Full Text Available The dynamical cluster-decay model (DCM of Gupta and collaborators has been applied successfully to the decay of very-light (A ∼ 30, light (A ∼ 40−80, medium, heavy and super-heavy mass compound nuclei for their decay to light particles (evaporation residues, ER, fusion-fission (ff, and quasi-fission (qf depending on the reaction conditions. We intend to extend here the application of DCM to study the extreme case of decay of very-light nuclear systems 20,21,22Ne∗ formed in 10,11B+10,11B reactions, for which experimental data is available for their binary symmetric decay (BSD cross sections, i.e., σBSD. For the systems under study, the calculations are presented for the σBSD in terms of their preformation and barrier penetration probabilities P0 and P. Interesting results are that in the decay of such lighter systems there is a competing reaction mechanism (specifically, the deep inelastic orbiting of non-compound nucleus (nCN origin together with ff. We have emipirically estimated the contribution of σnCN. Moreover, the important role of nuclear structure characteristics via P0 as well as angular momentum ℓ in the reaction dynamics are explored in the study.

  16. Study of 11Li and 10,11Be nuclei through elastic scattering and breakup reactions

    Science.gov (United States)

    Gaidarov, M. K.; Lukyanov, V. K.; Kadrev, D. N.; Zemlyanaya, E. V.; Antonov, A. N.; Lukyanov, K. V.; Spasova, K.

    2016-01-01

    The hybrid model of the microscopic optical potential (OP) is applied to calculate the 11Li+p, 10,11Be+p, and 10,11Be+12C elastic scattering cross sections at energies E energy approximation (HEA) theory. For the 11Li+p elastic scattering, the microscopic large-scale shell model (LSSM) density of 11Li is used, while the density distributions of 10,11Be nuclei obtained within the quantum Monte Carlo (QMC) model and the generator coordinate method (GCM) are utilized to calculate the microscopic OPs and cross sections of elastic scattering of these nuclei on protons and 12C. The depths of the real and imaginary parts of OP are fitted to the elastic scattering data, being simultaneously adjusted to reproduce the true energy dependence of the corresponding volume integrals. Also, the cluster models, in which 11Li consists of 2n-halo and the 9Li core having its own LSSM form of density and 11Be consists of a n-halo and the 10Be core, are adopted. Within the latter, we give predictions for the longitudinal momentum distributions of 9Li fragments produced in the breakup of 11Li at 62 MeV/nucleon on a proton target. It is shown that our results for the diffraction and stripping reaction cross sections in 11Be scattering on 9Be, 93Nb, 181Ta, and 238U targets at 63 MeV/nucleon are in a good agreement with the available experimental data.

  17. Study of 11Li and 10,11Be nuclei through elastic scattering and breakup reactions

    Directory of Open Access Journals (Sweden)

    Gaidarov M. K.

    2016-01-01

    Full Text Available The hybrid model of the microscopic optical potential (OP is applied to calculate the 11Li+p, 10,11Be+p, and 10,11Be+12C elastic scattering cross sections at energies E < 100 MeV/nucleon. The OP’s contain the folding-model real part (ReOP with the direct and exchange terms included, while its imaginary part (ImOP is derived within the high-energy approximation (HEA theory. For the 11Li+p elastic scattering, the microscopic large-scale shell model (LSSM density of 11Li is used, while the density distributions of 10,11Be nuclei obtained within the quantum Monte Carlo (QMC model and the generator coordinate method (GCM are utilized to calculate the microscopic OPs and cross sections of elastic scattering of these nuclei on protons and 12C. The depths of the real and imaginary parts of OP are fitted to the elastic scattering data, being simultaneously adjusted to reproduce the true energy dependence of the corresponding volume integrals. Also, the cluster models, in which 11Li consists of 2n-halo and the 9Li core having its own LSSM form of density and 11Be consists of a n-halo and the 10Be core, are adopted. Within the latter, we give predictions for the longitudinal momentum distributions of 9Li fragments produced in the breakup of 11Li at 62 MeV/nucleon on a proton target. It is shown that our results for the diffraction and stripping reaction cross sections in 11Be scattering on 9Be, 93Nb, 181Ta, and 238U targets at 63 MeV/nucleon are in a good agreement with the available experimental data.

  18. Synthesis of the new boron hydride nido-undecaborane(15), B11H15, and the x-ray structure of its conjugate base tetradecahydroundecaborate(1-), [B11H14]-

    International Nuclear Information System (INIS)

    Getman, T.D.; Krause, J.A.; Shore, S.G.

    1988-01-01

    The preparation of nido-undecaborane, B 11 H 15 , from the protonation of K[B 11 H 14 ] and the subsequent deprotonation of B 11 H 15 by P(CH 3 ) 3 to give [P(CH 3 ) 3 H][B 11 H 14 ] is described. The structure of [P(CH 3 ) 3 H][B 11 H 14 ] has been determined from single-crystal x-ray data. The spectral data indicate that the boron framework of B 11 H 15 is similar to that of [B 11 H 14 ] - . 11 references, 1 figure

  19. Basic visualization experiments on eutectic reaction of boron carbide and stainless steel under sodium-cooled fast reactor conditions

    International Nuclear Information System (INIS)

    Yamano, Hidemasa; Suzuki, Tohru; Kamiyama, Kenji; Kudo, Isamu

    2016-01-01

    This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (B 4 C) and stainless steel (SS) under a high temperature condition exceeding 1500degC as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the B 4 C-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a B 4 C pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the B 4 C-SS eutectic in upper part of the solidified test piece due to the density separation. (author)

  20. A study of 11 Be an 11 Li halo nuclei by core breakup reactions

    International Nuclear Information System (INIS)

    Grevy, S.

    1997-01-01

    The study of light nuclei with large neutron excess are very useful for the understanding of nuclear matter far from stability. The nuclear halo phenomenon has been observed for the first time for Z 11 Be and 11 Li halo nuclei. In this channel, the neutron is supposed not to participate to the reaction and then, when detected, to carry out the same properties as in the halo nucleus. The deduced widths of the neutron momentum distributions are different from the one extracted from the core distributions and with the more recent theoretical models. From these studies, it is also stressed that the properties of the core are essential to understand the halo phenomenon. In particular, the correlation between the core vibrations and the halo neutron are able to explain the emergence of the halo in 11 Be. (author)

  1. Utilization of boron irradiation filters in reactor neutron activation via epithermal (n,γ) and fast neutron reactions

    International Nuclear Information System (INIS)

    Chisela, F.

    1986-01-01

    The technique of instrumental neutron activation analysis based on irradiation with reactor epithermal and fast neutrons has been described and evaluated. Important characteristics of boron neutron absorbers used to remove thermal neutrons from the reactor neutron spectrum have been examined and compared with those of cadmium. Three boron compound shields, have been designed and constructed at the BER II 5MW reactor for use in epithermal neutron activation analysis of biological materials. The major advantages offered by these filters in this application include the flexibility of varying the filter thickness, the low radioactivity induced in the filters during irradiation, ease of fabrication and the relatively low cost of the filter materials. The radiation heating due to the 10 B(n,α) 7 Li-reaction has been experimentally investigated for the filters used and the results obtained confirm the necessity for efficient cooling of these filters during irradiation. Three irradiation facilities have been characterized with respect to the neutron flux density and the flux spatial distribution. An experiment has been designed and carried out to compensate the flux inhomogeneity in two irradiation positions of the DBV facility caused by the reactor geometry. Several biological samples including well characterized reference materials have been analysed after epithermal activation and the results compared with those obtained with the classical thermal neutron activation method. Improved sensitivity of determination has been found for elements with high resonance integral to thermal neutron cross section ratios (RI/σ 0 ). The range of elements that can be determined instrumentally is extended and the time scale of analysis is considerably reduced. (orig.) [de

  2. Proteomic analysis of cellular response induced by boron neutron capture reaction in human squamous cell carcinoma SAS cells

    International Nuclear Information System (INIS)

    Sato, Akira; Itoh, Tasuku; Imamichi, Shoji; Kikuhara, Sota; Fujimori, Hiroaki; Hirai, Takahisa; Saito, Soichiro; Sakurai, Yoshinori; Tanaka, Hiroki; Nakamura, Hiroyuki; Suzuki, Minoru

    2015-01-01

    To understand the mechanism of cell death induced by boron neutron capture reaction (BNCR), we performed proteome analyses of human squamous tumor SAS cells after BNCR. Cells were irradiated with thermal neutron beam at KUR after incubation under boronophenylalanine (BPA)(+) and BPA(−) conditions. BNCR mainly induced typical apoptosis in SAS cells 24 h post-irradiation. Proteomic analysis in SAS cells suggested that proteins functioning in endoplasmic reticulum, DNA repair, and RNA processing showed dynamic changes at early phase after BNCR and could be involved in the regulation of cellular response to BNCR. We found that the BNCR induces fragments of endoplasmic reticulum-localized lymphoid-restricted protein (LRMP). The fragmentation of LRMP was also observed in the rat tumor graft model 20 hours after BNCT treatment carried out at the National Nuclear Center of the Republic of Kazakhstan. These data suggest that dynamic changes of LRMP could be involved during cellular response to BNCR. - Highlights: • BNCR in human squamous carcinoma cells caused typical apoptotic features. • BNCR induced fragments of LRMP, in human squamous carcinoma and rat tumor model. • The fragmentation of LRMP could be involved in cellular response to BNCR.

  3. Boron-Doped Diamond (BDD) Coatings Protect Underlying Silicon in Aqueous Acidic Media–Application to the Hydrogen Evolution Reaction

    International Nuclear Information System (INIS)

    Halima, A.F.; Rana, U.A.; MacFarlane, D.R.

    2014-01-01

    Abstract: Silicon has potential application as a functional semiconductor electrode in proposed solar water splitting cells. It is abundant and has excellent photovoltaic attributes, however it is extremely susceptible to corrosion, even in the dark, resulting in the formation of an electrochemically passive oxide upon interaction with aqueous media. This work investigates the potential for conductive, inert and transparent boron doped diamond (BDD) coatings to protect p-type Silicon (p-Si). The stability and electrochemical performance of p-Si and p-Si|BDD were investigated using voltammetric techniques in 1 M H 2 SO 4 , before and after long-term exposure to the acidic medium (up to 280 hours) under no applied potential bias. Unprotected Si degraded very rapidly whilst BDD was shown to protect the underlying Si, as evident from I-V curves that indicated no increased resistance across the Si-diamond interface. Furthermore, BDD supported facile proton reduction at significantly lower onset potential for the hydrogen evolution reaction (up to -500 mV vs. SCE) compared with bare Si cathode (-850 mV vs. SCE). The activity of the BDD electrode/electrolyte interface was further improved by coating with platinum catalyst particles, to produce a p-Si|BDD|Pt strucure, which reduced the HER onset to nearly zero overpotential. Tafel analysis indicated that desirable electrochemical activity and stability were achieved for p-Si|BDD|Pt, making this a promising electrode for application in water splitting cells

  4. Large-Scale Fabrication of Boron Nitride Nanotubes via a Facile Chemical Vapor Reaction Route and Their Cathodoluminescence Properties

    Directory of Open Access Journals (Sweden)

    Zhong Bo

    2011-01-01

    Full Text Available Abstract Cylinder- and bamboo-shaped boron nitride nanotubes (BNNTs have been synthesized in large scale via a facile chemical vapor reaction route using ammonia borane as a precursor. The structure and chemical composition of the as-synthesized BNNTs are extensively characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and selected-area electron diffraction. The cylinder-shaped BNNTs have an average diameter of about 100 nm and length of hundreds of microns, while the bamboo-shaped BNNTs are 100–500 nm in diameter with length up to tens of microns. The formation mechanism of the BNNTs has been explored on the basis of our experimental observations and a growth model has been proposed accordingly. Ultraviolet–visible and cathodoluminescence spectroscopic analyses are performed on the BNNTs. Strong ultraviolet emissions are detected on both morphologies of BNNTs. The band gap of the BNNTs are around 5.82 eV and nearly unaffected by tube morphology. There exist two intermediate bands in the band gap of BNNTs, which could be distinguishably assigned to structural defects and chemical impurities. Additional file 1 Click here for file

  5. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester

    KAUST Repository

    Batool, Farhat

    2016-11-18

    Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.

  6. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester

    KAUST Repository

    Batool, Farhat; Emwas, Abdul-Hamid M.; Gao, Xin; Munawar, Munawar A.; Chotana, Ghayoor A.

    2016-01-01

    Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.

  7. Boron “stitching” reaction: a powerful tool for the synthesis of polyethylene-based star architectures

    KAUST Repository

    Zapsas, George; Ntetsikas, Konstantinos; Kim, Joey; Bilalis, Panagiotis; Gnanou, Yves; Hadjichristidis, Nikolaos

    2018-01-01

    The linking of macroanions with BFOEt leads to a 3-arm star with a boron junction point, which can serve as a macroinitiator for the polyhomologation of dimethylsulfoxonium methylide, thus enabling the synthesis of novel but not

  8. Boron “stitching” reaction: a powerful tool for the synthesis of polyethylene-based star architectures

    KAUST Repository

    Zapsas, George

    2018-02-07

    The linking of macroanions with BFOEt leads to a 3-arm star with a boron junction point, which can serve as a macroinitiator for the polyhomologation of dimethylsulfoxonium methylide, thus enabling the synthesis of novel but not

  9. One-step synthesis of an {sup 18}F-labeled boron-derived methionine analog. A substitute for {sup 11}C-methionine?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhen; Lan, Xiaoli [Huazhong University of Science and Technology, Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Wuhan (China); Huazhong University of Science and Technology, Hubei Key Laboratory of Molecular Imaging, Union Hospital, Tongji Medical College, Wuhan (China); Ehlerding, Emily B. [University of Wisconsin - Madison, Department of Medical Physics, Madison, WI (United States); Cai, Weibo [University of Wisconsin - Madison, Department of Medical Physics, Madison, WI (United States); University of Wisconsin - Madison, Department of Radiology, Madison, WI (United States); University of Wisconsin - Madison, Carbone Cancer Center, Madison, WI (United States)

    2018-04-15

    Amino acid-based tracers have been extensively investigated for positron emission tomography (PET) imaging of brain tumors, and {sup 11}C-methionine ({sup 11}C-MET) is one of the most extensively investigated. However, widespread clinical use of {sup 11}C-MET is challenging due to the short half-life of {sup 11}C and low radiolabeling yield. In this issue of the European Journal of Nuclear Medicine and Molecular Imaging, Yang and colleagues report an {sup 18}F-labeled boron-derived methionine analog, {sup 18}F-B-MET, as a potential substitute for {sup 11}C-MET in PET imaging of glioma. The push-button synthesis, highly efficient radiolabeling, and good imaging performance in glioma models make this tracer a promising candidate for future clinical translation. (orig.)

  10. Reporter-free potentiometric sensing of boronic acids and their reactions by using quaternary ammonium salt-functionalized polymeric liquid membranes.

    Science.gov (United States)

    Wang, Xuewei; Yue, Dengfeng; Lv, Enguang; Wu, Lei; Qin, Wei

    2014-02-18

    The tremendous applications of boronic acids (BAs) in chemical sensing, medical chemistry, molecular assembly, and organic synthesis lead to an urgent demand for developing effective sensing methods for BAs. This paper reports a facile and sensitive potentiometric sensor scheme for heterogeneous detection of BAs based on their unexpected potential responses on quaternary ammonium salt-doped polymeric liquid membranes. (11)B NMR data reveal that a quaternary ammonium chloride can trigger the hydrolysis of an electrically neutral BA in an aprotic solvent. Using the quaternary ammonium salt as the receptor, the BA molecules can be extracted from the sample solution into the polymeric membrane phase and undergo the concomitant hydrolysis. Such salt-triggered hydrolysis generates H(+) ions, which can be coejected into the aqueous phase with the counterions (e.g., Cl(-)) owing to their high hydrophilicities. The perturbation on the ionic partition at the sample-membrane interface changes the phase boundary potential and thus enables the potentiometric sensing of BAs. In contrast to other transduction methods for BAs, for which labeled or separate reporters are exclusively required, the present heterogeneous sensing scheme allows the direct detection of BAs without using any reporter molecules. This technique shows superior detection limits for BAs (e.g., 1.0 × 10(-6) M for phenylboronic acid) as compared to previously reported methods based on colorimetry, fluorimetry, and mass spectrometry. The proposed sensing strategy has also been successfully applied to potentiometric indication of the BA reactions with hydrogen peroxide and saccharides, which allows indirect and sensitive detection of these important species.

  11. Separation of boron isotopes by infrared laser

    International Nuclear Information System (INIS)

    Suzuki, Kazuya

    1995-01-01

    Vibrationally excited chemical reaction of boron tribromide (BBr 3 ) with oxygen (O 2 ) is utilized to separate 10 B and 11 B. Infrared absorption of 10 BBr 3 is at 11.68μ and that of 11 BBr 3 is at 12.18μ. The wavelengths of ammonia laser made in the laboratory were mainly 11.71μ, 12.08μ and 12.26μ. Irradiation was done by focussing the laser with ZnSe lens on the sample gas (mixture of 1.5 torr of natural BBr 3 and 4.5 torr of O 2 ) in the reaction cell. Depletions of 10 BBr 3 and 11 BBr 3 due to chemical reaction of BBr 3 with O 2 was measured with infrared spectrometer. The maximum separation factor β( 10 B/ 11 B) obtained was about 4.5 (author)

  12. Synthesis of boron and nitrogen co-doped carbon nanofiber as efficient metal-free electrocatalyst for the VO"2"+/VO_2"+ Redox Reaction

    International Nuclear Information System (INIS)

    Shi, Lang; Liu, Suqin; He, Zhen; Yuan, Hao; Shen, Junxi

    2015-01-01

    Boron or nitrogen mono-doped carbon nanofiber (CNF), and boron, nitrogen co-doped CNF are intentionally prepared as positive electrodes in a vanadium redox flow battery (VRFB). The structures and electrochemical properties of the materials are investigated by Scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry and electrochemical impendence spectroscopy. The experimental results indicate that either B or N mono-doped CNF shown better electrochemical performance than untreated one. Interestingly, for the B and N co-doped CNF, the separated case exhibited an outstanding electrochemical activity better than either B or N mono-doped case, while the bonded case leading to a sharp drop in conductivity and shown poor electrochemical performances. These results demonstrated that not the total amount of incorporated B and N but how the B and N are incorporated into carbon nanostructures determines the catalytic activity toward VO"2"+/VO_2"+ reaction. Moreover, the individual mechanism of the nitrogen and boron containing functional groups act as active sites have been analyzed.

  13. Elastic scattering and fusion studies in the reactions $^{10,11}$Be + $^{64}$Zn

    CERN Multimedia

    2002-01-01

    We propose to measure elastic scattering and fusion excitation functions for the reactions $^{10,11}$Be + $^{64}$Zn at 3.1 MeV/u . The aim of the experiment is to investigate possible effects of the halo structure of the $^{11}$Be nucleus on the reaction mechanisms at energy around the Coulomb barrier. For this purpose a comparison with the reaction induced by the $^{10}$Be nucleus is required.

  14. The 8Li(α,n)11B reaction and primordial nucleosynthesis

    International Nuclear Information System (INIS)

    Boyd, R.N.

    1992-01-01

    The cross section for the 8 Li(α,n) 11 B reaction, of importance to synthesis of 11 B and heavier nuclides following the big bang, has been measured using the radioactive beam facility of The Institute of Physical and Chemical Reasearch (RIKEN). The reaction cross section was found to be about five times larger than that estimated from the time reversed reaction cross section. (author)

  15. A ditopic fluorescence sensor for saccharides and mercury based on a boronic-acid receptor and desulfurisation reaction.

    Science.gov (United States)

    Xing, Zhitao; Wang, Hui-Chen; Cheng, Yixiang; James, Tony D; Zhu, Chengjian

    2011-11-04

    Two boron-contained fluorescent sensors, 1 and 2, based on coumarin have been prepared. The fluorescence response of the two systems was investigated with addition of saccharide and mercury ions. Sensor 2 behaves as a bifunctional fluorescent switch with chemical inputs of D-fructose and mercury ions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Fusion energy using avalanche increased boron reactions for block-ignition by ultrahigh power picosecond laser pulses

    Czech Academy of Sciences Publication Activity Database

    Hora, H.; Korn, Georg; Giuffrida, Lorenzo; Margarone, Daniele; Picciotto, A.; Krása, Josef; Jungwirth, Karel; Ullschmied, Jiří; Lalousis, P.; Eliezer, S.; Miley, G. H.; Moustaizis, S.; Mourou, G.

    2015-01-01

    Roč. 33, č. 4 (2015), s. 607-619 ISSN 0263-0346 Institutional support: RVO:68378271 ; RVO:61389021 Keywords : fusion energy without radiation problem * boron fusion by lasers * non-linear force-driven block ignition Subject RIV: BL - Plasma and Gas Discharge Physics; BH - Optics, Masers, Lasers (UFP-V) Impact factor: 1.649, year: 2015

  17. 11. IAEA consultants' meeting of the nuclear reaction data centers. Obninsk, 7-11 October 1991

    International Nuclear Information System (INIS)

    Lemmel, H.D.

    1992-03-01

    This report summarizes the 1991 co-ordination meeting in Obninsk, Russia, of the national and regional nuclear reaction data centers, convened by the IAEA at regular intervals. The main topics are: the international exchange of nuclear reaction data by means of the ''EXFOR'' system, and the further development of this system; the ''CINDA'' system as an international index and bibliography to neutron reaction data; the sharing of the workload for speedy and reliable nuclear data compilation; the exchanged and documentation of evaluated data libraries in ENDF format, with the goal of rendering data center services to data users in IAEA Member States by means of computer retrievals, online services and printed materials

  18. Hydrolytic Stability of Boronate Ester-Linked Covalent Organic Frameworks

    KAUST Repository

    Li, Huifang

    2018-01-30

    The stability of covalent organic frameworks (COFs) is essential to their applications. However, the common boronate ester-linked COFs are susceptible to attack by nucleophiles (such as water molecules) at the electron-deficient boron sites. To provide an understanding of the hydrolytic stability of the representative boronate ester-linked COF-5 and of the associated hydrolysis mechanisms, density functional theory (DFT) calculations were performed to characterize the hydrolysis reactions of the molecule formed by the condensation of 1,4-phenylenebis(boronic acid) (PBBA) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) monomers; two cases were considered, one dealing with the freestanding molecule and the other with the molecule interacting with COF layers. It was found that the boronate ester (B–O) bond dissociation, which requires one H2O molecule, has a relatively high energy barrier of 22.3 kcal mol−1. However, the presence of an additional H2O molecule significantly accelerates hydrolysis by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic stability of COF-5 crystals.

  19. Study of a neutron producing target via the 7Li(p,n)7Be reaction near its energy threshold for BNCT (boron neutron capture therapy)

    International Nuclear Information System (INIS)

    Burlon, Alejandro; Kreiner, Andres J.; Debray, Mario E.; Stoliar, Pablo; Kesque, Jose M.; Naab, Fabian; Ozafran, Mabel J.; Schuff, Juan; Vazquez, Monica; Caraballo, Maria E.; Valda, Alejandro; Somacal, Hector; Davidson, Miguel; Davidson, Jorge

    2000-01-01

    In the framework of Accelerator Based BNCT (AB-BNCT) the 7 Li(p,n) 7 Be reaction near its energy threshold is one of the most promising. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by the tandem accelerator TANDAR at CNEA's facilities in Buenos Aires. A water-filled phantom, containing a boron sample was irradiated with the resulting neutron beam. The boron neutron capture reaction produces a 0.478 MeV gamma ray in 94 % of the cases. The neutron yield was monitored by detecting this gamma ray using a germanium detector with an 'anti-Compton' shield. Moreover, the thermal neutron flux was evaluated at different depths inside the phantom using bare and Cd-covered gold foils. A maximum neutron thermal flux of 1.4 x 10 8 1/(cm 2 -s-mA) was obtained at 4.2 cm from the phantom surface. (author)

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

    Science.gov (United States)

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

    2016-08-04

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

  1. Boron isotope fractionation in magma via crustal carbonate dissolution

    Science.gov (United States)

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

    2016-08-01

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

  2. The interplay between hydrogen evolution reaction and nitrate reduction on boron-doped diamond in aqueous solution: the effect of alkali cations

    International Nuclear Information System (INIS)

    Manzo-Robledo, A.; Lévy-Clément, C.; Alonso-Vante, N.

    2014-01-01

    The nitrate ion reduction was studied on boron-doped diamond (BDD) electrodes by real-time on-line differential electrochemical mass spectrometry (DEMS) coupled with chronoamperometry in K + , Na + cation-containing electrolyte solutions. It was found, via steady state voltammetry, that the hydrogen evolution reaction (HER) was affected by the presence of K + or Na + . A moderate HER occurs in K + -containing electrolyte solution favoring the reaction between NO 3 − and H 2 species, whereas in Na + -containing electrolyte solutions, the HER kinetics was more important leading to a suppression of molecular nitrogen generation. The use of isotope-labeled nitrogen and DEMS confirmed the influence of alkali cations toward the nitrate ion reduction

  3. Synthesis of 11C-labelled haloalkanonitriles and examples of their use in some alkylation reactions

    International Nuclear Information System (INIS)

    Hoernfeldt, K.; Antoni, G.; Laangstroem, B.

    1992-01-01

    The synthesis of the 11 C-labelled bifunctional precursors 4-iodobutyro[ 11 C]nitrile (1), 4-tosyloxybutyro[ 11 C]nitrile (2), 5-iodovalero[ 11 C]nitrile (3), 5-toxyloxyvalero[ 11 C]nitrile (4) and 4-bromopentano[ 11 C]nitrile (5) are presented. The nucleophilic substitution reactions of [ 11 C]cyanide with dibromides, diiodides, ditosylates or mixed iodotosylates producing 1-5 have been carried out in different solvents and the labelled products were obtained in 62-98% radiochemical yields (not isolated), with a total synthesis time of 5 min counted from the end of the hydrogen [ 11 C]cyanide synthesis. The labelled haloalkanonitriles 1 and 3 have also been used in some alkylation reactions with various carbon and oxygen nucleophiles. (au)

  4. A New Boron Analysis Method

    Energy Technology Data Exchange (ETDEWEB)

    Weitman, J; Daaverhoeg, N; Farvolden, S

    1970-07-01

    In connection with fast neutron (n, {alpha}) cross section measurements a novel boron analysis method has been developed. The boron concentration is inferred from the mass spectrometrically determined number of helium atoms produced in the thermal and epithermal B-10 (n, {alpha}) reaction. The relation between helium amount and boron concentration is given, including corrections for self shielding effects and background levels. Direct and diffusion losses of helium are calculated and losses due to gettering, adsorption and HF-ionization in the release stage are discussed. A series of boron determinations is described and the results are compared with those obtained by other methods, showing excellent agreement. The lower limit of boron concentration which can be measured varies with type of sample. In e.g. steel, concentrations below 10-5 % boron in samples of 0.1-1 gram may be determined.

  5. Contribution to the study of the reaction p + {sup 11}B = 3 {alpha} by the coincidence method; Contribution a l'etude de la reaction p + {sup 11}B = 3 {alpha} par la methode des coincidences

    Energy Technology Data Exchange (ETDEWEB)

    Laugier, J Ph [Commissariat a l' Energie Atomique, Bruyeres-le-Chatel (France). Centre d' Etudes

    1969-07-01

    We have studied the production mode of the 3 {alpha} system in the reaction p + {sup 11}B = {sup 12}C{sup *} = {alpha} + {sup 8}Be{sup *}; {sup 8}Be{sup *} = {alpha} + {alpha}. We have got some information for three different effects: the influence of the {sup 8}Be residual nucleus states = sequential decay; the influence of the {sup 12}C compound nucleus states = spin effect; an interference effect. We give a theoretical expression of the different spectra which take into account the observed phenomena. We have taken, as a parameter, the phase shift, between the waves associated with the detected particles, which produce the interference effect. The main characteristics of the experimental devices are : self supporting boron targets; cooled semiconductor detectors; multi-parametric system: for each nuclear event three parameters are recorded: the energies of the detected particles and the time of the detection; Recording system: the information are recorded on a magnetic tape and at the same time treated with an on line CAE 510 computer. The CAE 510 computer is used in delayed time to analyse the experimental data. (author) [French] Nous avons etudie le mecanisme de production du systeme 3 {alpha} dans la reaction: p + {sup 11}B = {sup 12}C{sup *} = {alpha} + {sup 8}Be{sup *}; {sup 8}Be{sup *} = {alpha} + {alpha}. Cette etude nous a permis de mettre en evidence trois effets de nature differente: l'effet des niveaux du noyau intermediaire {sup 8}Be reaction sequentielle; l'effet des niveaux du noyau compose {sup 12}C = effet de spin; -un effet d'interferences. Nous avons pu donner une expression theorique du spectre, rendant compte d'une facon satisfaisante des phenomenes observes. Pour cela nous avons considere le dephasage, entre les ondes associees aux particules detectees, qui produit les interferences, comme un parametre arbitraire. Du point de vue experimental les caracteristiques principales du materiel utilise sont les suivantes: utilisation de cibles de

  6. Structure of the excited states of 11Be reached through the reaction d(10Be,p)11Be

    International Nuclear Information System (INIS)

    Delaunay, F.

    2003-10-01

    The one-neutron transfer reaction d( 10 Be,p) 11 Be has been studied at 32 A.MeV at GANIL with a 10 Be secondary beam. Protons were detected by the silicon strip array MUST. The ground state and excited states of 11 Be at 0.32, 1.78 and 3.41 MeV were populated, demonstrating the feasibility of transfer reactions induced by radioactive beams leading to bound and unbound states. A DWBA (distorted wave born approximation) analysis indicates for the 3.41 MeV state spin and parity 3/2 + or 5/2 + and a spectroscopic factor of 0.18 or 0.11, respectively. A broad structure centered at 10 MeV is also observed and corresponds to transfer to the 1d sub-shells. If one assumes that only the 1d3/2 orbital contributes to this structure, the splitting of the 1d neutron states in 11 Be is estimated to be 6.3 MeV. Using a 2-particle-RPA (random phase approximation) model, we have shown that neutron-neutron correlations play an important role in the inversion between the 2s1/2 and 1p1/2 neutron states in 11 Be. (author)

  7. Boronate esters: Synthesis, characterization and molecular base receptor analysis

    Science.gov (United States)

    Gómez-Jaimes, Gelen; Barba, Victor

    2014-10-01

    The synthesis of three boronate esters obtained by reacting 4-fluorophenylboronic (1), 4-iodophenylboronic (2) and 3,4-chlorophenylboronic (3) acids with 2,4,5-trihidroxybenzaldehyde is reported. The structural characterization was determined by spectroscopic and spectrometric techniques. The boron atom was evaluated to acts as Lewis acid center in the reaction with pyridine (Py), triethylamine (TEA) and fluoride anion (F-). The titration method was followed by UV-Vis and 11B NMR spectroscopy; results indicate the good interaction with the fluoride ion but poor coordination towards pyridine in solution.

  8. 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

  9. Synthesis of boron-containing heterocyclic compounds

    International Nuclear Information System (INIS)

    Azev, Yuri; Slepukhina, Irina; Gabel, Detlef

    2004-01-01

    The synthesis of boron-containing 1,3,5-triazines and 1,2,4-triazines is described. Derivatives of 1,3,5-triazine containing the o-carborane cluster have been obtained by reacting the corresponding propargyl derivatives with B 10 H 14 . Derivatives of 1,2,4-triazine containing the B 12 H 12 2- cluster have been obtained by nucleophilic substitution of ethylsulfone derivatives with B 12 H 11 SH 2- . They have been isolated in their ring-protonated form. Reaction of RNH 2 -B 8 H 11 NH-R with stericly demanding heterocycles failed, either for steric or for solubility reasons

  10. Dissociation reactions of the 11Be one-neutron halo: the interplay between structure and reaction mechanism

    International Nuclear Information System (INIS)

    Anne, R.; Lewitowicz, M.; Saint-Laurent, M.G.; Arnell, S.E.; Jonson, B.; Nilsson, T.; Nyman, G.; Wilhelmsen Rolander, K.; Esbensen, H.; Wolski, D.

    1992-01-01

    Reactions of a radioactive 11 Be beam at 41 MeV/u have been investigated. The absolute magnitude of the differential cross-sections of the forward neutrons in the exclusive ( 10 Be + n) channel can be accounted for quantitatively in a simple model. The narrow distribution from high-Z targets turns out to arise from Coulomb dissociation whereas the broad distribution from the beryllium target is due to diffraction dissociation

  11. Preliminary study on 2-dimensional distributions of 10B reaction rate in a water phantom with boron-doped CR-39 for 7Li(p, n)7Be neutrons by 1.95 MeV protons

    International Nuclear Information System (INIS)

    Hasegawa, Y.; Tanaka, K.; Tsuruta, T.

    2000-01-01

    In an Accelerator-based neutron irradiation field using 7 Li(p, n) 7 Be neutrons by 1.95 MeV protons, the distributions of 10 B reaction rates and thermal neutron fluence in a water phantom were measured using Boron-doped CR-39 and Au activation analysis, respectively. Comparing the results of the measurements, we discussed the validity of the evaluation method of 10 B reaction rate using thermal neutron fluence. (author)

  12. Boron Toxicity Tolerance in Barley through Reduced Expression of the Multifunctional Aquaporin HvNIP2;11[W

    Science.gov (United States)

    Schnurbusch, Thorsten; Hayes, Julie; Hrmova, Maria; Baumann, Ute; Ramesh, Sunita A.; Tyerman, Stephen D.; Langridge, Peter; Sutton, Tim

    2010-01-01

    Boron (B) toxicity is a significant limitation to cereal crop production in a number of regions worldwide. Here we describe the cloning of a gene from barley (Hordeum vulgare), underlying the chromosome 6H B toxicity tolerance quantitative trait locus. It is the second B toxicity tolerance gene identified in barley. Previously, we identified the gene Bot1 that functions as an efflux transporter in B toxicity-tolerant barley to move B out of the plant. The gene identified in this work encodes HvNIP2;1, an aquaporin from the nodulin-26-like intrinsic protein (NIP) subfamily that was recently described as a silicon influx transporter in barley and rice (Oryza sativa). Here we show that a rice mutant for this gene also shows reduced B accumulation in leaf blades compared to wild type and that the mutant protein alters growth of yeast (Saccharomyces cerevisiae) under high B. HvNIP2;1 facilitates significant transport of B when expressed in Xenopus oocytes compared to controls and to another NIP (NOD26), and also in yeast plasma membranes that appear to have relatively high B permeability. We propose that tolerance to high soil B is mediated by reduced expression of HvNIP2;1 to limit B uptake, as well as by increased expression of Bot1 to remove B from roots and sensitive tissues. Together with Bot1, the multifunctional aquaporin HvNIP2;1 is an important determinant of B toxicity tolerance in barley. PMID:20581256

  13. Reaction of 11 C-benzoyl chlorides with metalloid reagents: 11 C-labeling of benzyl alcohols, benzaldehydes, and phenyl ketones from [11 C]CO.

    Science.gov (United States)

    Roslin, Sara; Dahl, Kenneth; Nordeman, Patrik

    2018-01-26

    In this article, we describe the carbon-11 ( 11 C, t 1/2  = 20.4 minutes) labeling of benzyl alcohols, benzaldehydes, and ketones using an efficient 2-step synthesis in which 11 C-carbon monoxide is used in an initial palladium-mediated reaction to produce 11 C-benzoyl chloride as a key intermediate. In the second step, the obtained 11 C-benzoyl chloride is further treated with a metalloid reagent to furnish the final 11 C-labeled product. Benzyl alcohols were obtained in moderated to high non-isolated radiochemical yields (RCY, 35%-90%) with lithium aluminum hydride or lithium aluminum deuteride as metalloid reagent. Changing the metalloid reagent to either tributyltin hydride or sodium borohydride, allowed for the reliable syntheses of 11 C-benzaldehydes in RCYs ranging from 58% to 95%. Finally, sodium tetraphenylborate were utilized to obtain 11 C-phenyl ketones in high RCYs (77%-95%). The developed method provides a new and efficient route to 3 different classes of compounds starting from aryl iodides or aryl bromides. Copyright © 2018 John Wiley & Sons, Ltd.

  14. Complete kinematics study of the 11B+p→3α reaction

    DEFF Research Database (Denmark)

    Fynbo, H.O.U.; Laursen, K.L.; Riisager, K.

    2012-01-01

    The 11B(p,3α) reaction measured in complete kinematics is used to search for broad resonances in 12C. Evidence for natural parity states around 10 MeV and 12 MeV is presented. The most likely assignment is 2+. Measurements of Dalitz distributions from the 2+ and 2- states at 16.11 MeV and 16.57 Me...

  15. Social categorization and fear reactions to the September 11th terrorist attacks

    NARCIS (Netherlands)

    Dumont, M.; Yzerbyt, V.Y.; Wigboldus, D.H.J.; Gordijn, E.H.

    2003-01-01

    Two experiments were run in The Netherlands and Belgium 1 week after the terrorist attacks against the World Trade Center in New York on September 11, 2001. The aim was to investigate whether social categorization affected emotional reactions, behavioral tendencies, and actual behaviors. Results

  16. Study of reactions induced by the halo nucleus 11Li with the active target MAYA

    International Nuclear Information System (INIS)

    Roger, Th.

    2009-09-01

    Active targets are perfect tools for the study of nuclear reactions induced by very low intensity radioactive ion beams. They also enable the simultaneous study of direct and compound nuclear reactions. The active target MAYA, built at GANIL, has been used to study the reactions induced by a 4.3*A MeV 11 Li beam at the ISAC2 accelerator TRIUMF (Canada). The angular distributions for the elastic scattering and the one and two neutron transfer reaction have been reconstructed. The elastic scattering angular distribution indicates a strong enhancement of the flux absorption with respect to the neighbouring nuclei. From a coupled channel analysis of the two neutron transfer reaction for different three body models, the information on the structure of the halo of the Borromean nucleus 11 Li have been extracted. Meanwhile, the energy dependence of the elastic scattering reaction has been studied, using the active target MAYA as a thick target. The resulting spectrum shows a resonance around 3 MeV centre of mass. This resonance could be an isobaric analog state of 12 Li, observed in 12 Be. R matrix calculations have been performed in order to extract the parameters (spin and parity) of this state. (author)

  17. Separation process for boron isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rockwood, S D

    1975-06-12

    The method according to the invention is characterized by the steps of preparing a gaseous mixture of BCl/sub 3/ containing the isotopes of boron and oxygen as the extractor, irradiating that mixture in the tube of the separator device by means of P- or R-lines of a CO/sub 2/ laser for exciting the molecules containing a given isotope of boron, simultaneously irradiating the mixture with UV for photodissociating the excited BCl/sub 3/ molecules and separating BCl/sub 3/ from the reaction products of photodissociation and from oxygen. Such method is suitable for preparing boron used in nuclear reactors.

  18. N{sub 2}O + SO{sub 2} reaction over Si- and C-doped boron nitride nanotubes: A comparative DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Esrafili, Mehdi D., E-mail: esrafili@maragheh.ac.ir; Saeidi, Nasibeh

    2017-05-01

    Highlights: • The mechanisms of N{sub 2}O + SO{sub 2} reaction are investigated over Si- and C-doped BNNTs. • Both Si- and C-doped BNNTs can be used as an efficient catalyst for the N{sub 2}O + SO{sub 2} reaction. • The 2N{sub 2}O → O{sub 2} + N{sub 2} reaction needs a large activation energy over both surfaces. - Abstract: Density functional theory calculations are performed to investigate the mechanisms of N{sub 2}O reduction by SO{sub 2} over Si- and C-doped (6,0) boron nitride nanotubes (BNNTs). According to our results, the Si or C adatom can be strongly stabilized over the vacancy defect of the BNNT. The adsorption energy of Si and C atoms over defective BNNT is calculated to be −297.3 and −333.7 kcal/mol, respectively, indicating a strong interaction between these dopant atoms and the tube surface. The N{sub 2}O reduction reaction includes the decomposition of N{sub 2}O (i.e. N{sub 2}O → N{sub 2} + O*), followed by the reduction of O* by SO{sub 2} molecule (i.e. SO{sub 2} + O* → SO{sub 3}). The calculated energy barrier of the SO{sub 2} + O* → SO{sub 3} reaction on Si- and C-doped BNNTs is 2.4 and 5.4 kcal/mol, respectively. Moreover, the effects of tube diameter and length on the N{sub 2}O reduction are studied in detail. The disproportionation of N{sub 2}O molecules (2N{sub 2}O → 2N{sub 2} + O{sub 2}) over both surfaces needs a quite large activation energy, which indicates the impossibility of this reaction at ambient condition. The results show that both Si- and C-doped BNNTs can be viewed as an effective green catalyst for the reduction of N{sub 2}O.

  19. Low electron density of states at the boron site of TMB{sub 2} (TM = Ti, Zr, Hf, and Nb): a {sup 11}B NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, S.; Zogal, O.J.; Peshev, P

    2004-11-30

    The local density of states at the boron site in TMB{sub 2} (TM=Ti, Zr, Hf, and Nb) has been examined using the solid-state {sup 11}B NMR technique. The magic angle spinning (MAS) NMR spectra at room temperature and the spin-lattice relaxation rates have been measured as functions of temperature (30-293 K). The resonance line shifts are small and become more negative in the direction from 3d- to 5d-elements. The relaxation rates follow a linear law characteristic of hyperfine magnetic interaction with conduction electrons. With borides of IV group metals the data can be understood in terms of a very low s-electron density of states and absence of a p-character of the conduction electron wave function at the Fermi level while in the case of NbB{sub 2} a small partial p-electron density of states is assumed. Then, the results are in good agreement with the earlier theoretical prediction.

  20. Beneficial effect of boron in layered sodium-ion cathode materials - The example of Na2/3B0.11Mn0.89O2

    Science.gov (United States)

    Vaalma, Christoph; Buchholz, Daniel; Passerini, Stefano

    2017-10-01

    Sodium-ion batteries are regarded as a complementary drop-in technology to lithium-ion batteries because they promise lower cost and a higher degree of environmental friendliness. Among other reasons, these benefits come from the use of manganese-based materials, whose stabilization via cation substitution is intensively studied to improve the electrochemical performance. Although multiple elements have been considered as substituent, surprisingly, boron has not been reported for layered sodium-ion cathode materials up to date. Our investigation of layered Na2/3B0.11Mn0.89O2 reveals an unexpectedly good electrochemical performance, with charge and discharge capacities of more than 175 mAh g-1 at 10 mA g-1 and 135 mAh g-1 at 500 mA g-1. The measured capacities are among the highest ever reported for sodium-based layered oxides in the potential range of 4.0-2.0 V vs. Na/Na+.

  1. Spectrographic determination of boron and silicon in uranium tetrafluoride: Study of the chemical reactions in the electrode cavity when ZnO is used as a uranium excitation suppressor

    International Nuclear Information System (INIS)

    Alduan, F. A.; Capdevila, C.; Roca, M.

    1973-01-01

    A method has been developed for determining traces of boron and silicon in uranium tetrafluoride. Use is made of zinc oxide to decrease the volatilization of uranium and achieve high sensitivities. The thermochemical reactions which occur in the anode cavity during the arcing process have been investigated. UO 2 and a uranium, zinc and fluorine compound, both less volatile than uranium tetrafluoride, are formed. (Author)

  2. Exclusive and restricted inclusive reactions involving the 11Be one-neutron halo

    International Nuclear Information System (INIS)

    Anne, R.; Emling, H.; Hansen, P.G.; Hornshoj, P.; Bimbot, R.; Dogny, S.

    1993-01-01

    Reactions of a 41 MeV/u beam of the radioactive halo nucleus 11 Be have been studied with a counter telescope coupled to an array of neutron detectors. The technique allows to determine single-neutron inclusive and exclusive angular distributions. The targets (Be, Ti and Au) were chosen to illustrate the relative roles played by nuclear and Coulomb mechanisms. It is shown that for the dissociation process it is possible to account almost quantitatively for the integral, single- and double-differential cross-sections from models without free parameters including the Coulomb, Serber and Glauber (diffraction dissociation) mechanisms. (K.A.). 56 refs., 11 figs., 1 tab

  3. Study on the Formation of Reaction Phase to Si Addition in Boron Steel Hot-Dipped in Al–7Ni Alloy

    Directory of Open Access Journals (Sweden)

    Jung-Gil Yun

    2017-11-01

    Full Text Available In order to reduce the intermetallic compounds formed during the application of an Al–7Ni wt % hot-dip multifunctional coating on boron steel, developed for Tailor Welded Blanks (TWB and hot stamping, 2–6 wt % Si was added to the coating to change the reaction layer. The coating was run at 690 °C for 120 s. Al9FeNi phases were formed on the steel interface, Fe2Al5 was formed on the steel, FeAl3 was generated between the existing layers, and flake-type Al2Fe3Si3 was formed in the Fe2Al5 phase, depending on the Si content. In addition, as Si was added to the coating, the thickness of the Fe2Al5 phase decreased and the thickness of the Al9FeNi phase and Al2Fe3Si3 increased. The decrease in the thickness of the Fe2Al5 phase was mainly due to the effect of the Si solid solution and the Al2Fe3Si3 formation in the Fe2Al5 phase. The reason for the growth of Al9FeNi is that the higher the Si content in the coating, the more the erosion of the interface of the steel material due to the coating solution. Therefore, the outflow of Fe into the coating liquid increased.

  4. Structure of states in 12Be via the 11Be( d,p) reaction

    Science.gov (United States)

    Kanungo, R.; Gallant, A. T.; Uchida, M.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Ball, G. C.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Brown, B. A.; Buchmann, L.; Colosimo, S. J.; Clark, R. M.; Cline, D.; Cross, D. S.; Dare, H.; Davids, B.; Drake, T. E.; Djongolov, M.; Finlay, P.; Galinski, N.; Garrett, P. E.; Garnsworthy, A. B.; Green, K. L.; Grist, S.; Hackman, G.; Harkness, L. J.; Hayes, A. B.; Howell, D.; Hurst, A. M.; Jeppesen, H. B.; Leach, K. G.; Macchiavelli, A. O.; Oxley, D.; Pearson, C. J.; Pietras, B.; Phillips, A. A.; Rigby, S. V.; Ruiz, C.; Ruprecht, G.; Sarazin, F.; Schumaker, M. A.; Shotter, A. C.; Sumitharachchi, C. S.; Svensson, C. E.; Tanihata, I.; Triambak, S.; Unsworth, C.; Williams, S. J.; Walden, P.; Wong, J.; Wu, C. Y.

    2010-01-01

    The s-wave neutron fraction of the 0 levels in 12Be has been investigated for the first time through the 11Be(d,p) transfer reaction using a 5 A MeV11Be beam at TRIUMF, Canada. The reaction populated all the known bound states of 12Be. The ground state s-wave spectroscopic factor was determined to be 0.28-0.07+0.03 while that for the long-lived 02+ excited state was 0.73-0.40+0.27. This observation, together with the smaller effective separation energy indicates enhanced probability for an extended density tail beyond the 10Be core for the 02+ excited state compared to the ground state.

  5. Use of a microwave cavity to reduce reaction times in radiolabelling with [11C]cyanide

    International Nuclear Information System (INIS)

    Thorell, J.-O.; Stone-Elander, S.; Elander, N.

    1992-01-01

    Advantages of using a microwave cavity over thermal treatment are demonstrated for radiolabelling reactions with [ 11 C]cyanide. For comparison purposes, two literature syntheses involving typical cyanide chemistry at rather vigorous conditions were investigated: cyano-de-halogenation with subsequent hydrolysis of the nitrile and the Bucher-Strecker synthesis of an aromatic amino acid. Comparable yields were obtained with intensities <100 W in reaction times that were 1/15 to 1/20th those used in thermal methods. Even rates of slower nucleophilic substitutions could be increased by manipulating the polarity of the medium. For the short-lived radionuclide carbon-11, such time gains result in radioactivity gains at the end-of-synthesis on the order of 70-100%. (Author)

  6. Elastic scattering and charge exchange reaction studies with {sup 6}He, {sup 10,11}Be

    Energy Technology Data Exchange (ETDEWEB)

    Roussel-Chomaz, P; Cortina-Gil, M D; Mittig, W; Casandjian, J M; Chartier, M [Grand Accelerateur National d` Ions Lourds (GANIL), 14 - Caen (France); Alamanos, N; Auger, F; Fekou-Youmbi, V [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee; Barrette, J [McGill Univ., Montreal, PQ (Canada); Blumenfeld, Y [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; and others

    1996-12-31

    The elastic scattering and charge exchange reaction of {sup 6}He, {sup 10,11}Be secondary beams on proton and {sup 12}C targets have been measured. The combined use of SISSI and SPEG allowed to obtain very good quality data in terms of energy and angular resolution. Preliminary analyses of the angular distributions using global parameter set for the optical model potentials, as well as more microscopic approaches are presented. (author). 14 refs.

  7. Application of in situ current normalized PIGE method for determination of total boron and its isotopic composition

    International Nuclear Information System (INIS)

    Chhillar, Sumit; Acharya, R.; Sodaye, S.; Pujari, P.K.

    2014-01-01

    A particle induced gamma-ray emission (PIGE) method using proton beam has been standardized for determination of isotopic composition of natural boron and enriched boron samples. Target pellets of boron standard and samples were prepared in cellulose matrix. The prompt gamma rays of 429 keV, 718 keV and 2125 keV were measured from 10 B(p,αγ) 7 Be, 10 B(p, p'γ) 10 B and 11 B(p, p'γ) 11 B nuclear reactions, respectively. For normalizing the beam current variations in situ current normalization method was used. Validation of method was carried out using synthetic samples of boron carbide, borax, borazine and lithium metaborate in cellulose matrix. (author)

  8. Degradation of the beta-blocker propranolol by electrochemical advanced oxidation processes based on Fenton's reaction chemistry using a boron-doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Isarain-Chavez, Eloy; Rodriguez, Rosa Maria; Garrido, Jose Antonio; Arias, Conchita; Centellas, Francesc; Cabot, Pere Lluis [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.ed [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-12-15

    The electro-Fenton (EF) and photoelectro-Fenton (PEF) degradation of solutions of the beta-blocker propranolol hydrochloride with 0.5 mmol dm{sup -3} Fe{sup 2+} at pH 3.0 has been studied using a single cell with a boron-doped diamond (BDD) anode and an air diffusion cathode (ADE) for H{sub 2}O{sub 2} electrogeneration and a combined cell containing the above BDD/ADE pair coupled in parallel to a Pt/carbon felt (CF) cell. This naphthalene derivative can be mineralized by both methods with a BDD anode. Almost overall mineralization is attained for the PEF treatments, more rapidly with the combined system due to the generation of higher amounts of hydroxyl radical from Fenton's reaction by the continuous Fe{sup 2+} regeneration at the CF cathode, accelerating the oxidation of organics to Fe(III)-carboxylate complexes that are more quickly photolyzed by UVA light. The homologous EF processes are less potent giving partial mineralization. The effect of current density, pH and Fe{sup 2+} and drug concentrations on the oxidation power of PEF process in combined cell is examined. Propranolol decay follows a pseudo first-order reaction in most cases. Aromatic intermediates such as 1-naphthol and phthalic acid and generated carboxylic acids such as maleic, formic, oxalic and oxamic are detected and quantified by high-performance liquid chromatography. The chloride ions present in the starting solution are slowly oxidized at the BDD anode. In PEF treatments, all initial N of propranolol is completely transformed into inorganic ions, with predominance of NH{sub 4}{sup +} over NO{sub 3}{sup -} ion.

  9. Nuclear reactions with 11C and 14O radioactive ion beams

    International Nuclear Information System (INIS)

    Guo, Fanqing

    2004-01-01

    Radioactive ion beams (RIBs) have been shown to be a useful tool for studying proton-rich nuclides near and beyond the proton dripline and for evaluating nuclear models. To take full advantage of RIBs, Elastic Resonance Scattering in Inverse Kinematics with Thick Targets (ERSIKTT), has proven to be a reliable experimental tool for investigations of proton unbound nuclei. Following several years of effort, Berkeley Experiments with Accelerated Radioactive Species (BEARS), a RIBs capability, has been developed at the Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The current BEARS provides two RIBs: a 11C beam of up to 2x108 pps intensity on target and an 14O beam of up to 3x104 pps intensity. While the development of the 11C beam has been relatively easy, a number of challenges had to be overcome to obtain the 14O beam. The excellent 11C beam has been used to investigate several reactions. The first was the 197Au(11C,xn)208-xnAt reaction, which was used to measure excitation functions for the 4n to 8n exit channels. The measured cross sections were generally predicted quite well using the fusion-evaporation code HIVAP. Possible errors in the branching ratios of ?? decays from At isotopes as well as the presence of incomplete fusion reactions probably contribute to specific overpredictions. 15F has been investigated by the p(14O,p)14O reaction with the ERSIKTT technology. Several 14O+p runs have been performed. Excellent energy calibration was obtained using resonances from the p(14N,p)14N reaction in inverse kinematics, and comparing the results to those obtained earlier with normal kinematics. The differences between 14N+p and 14O+p in the stopping power function have been evaluated for better energy calibration. After careful calibration, the energy levels of 15F were fitted with an R-matrix calculation. Spins and parities were assigned to the two observed resonances. This new measurement of the 15F ground state supports the disappearance of the Z = 8

  10. Synthesis of 1-/sup 11/C-labelled ethyl, propyl, butyl and isobutyl iodides and examples of alkylation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Laangstroem, B.; Antoni, G.; Gullberg, P.; Halldin, C.; Naagren, K.; Rimland, A.; Svaerd, H.

    1986-01-01

    New /sup 11/C-labelled precursors (1-/sup 11/C)ethyl,(1-/sup 11/C)propyl, (1-/sup 11/C)butyl, and (1-/sup 11/C)isobutyl iodides have been prepared by a 3-step reaction route using a one-pot system. The labelled iodides were obtained in 20-55% radiochemical yields and 65-95% radiochemical purities, with a total time for synthesis of the order of 10-14 min. The labelled iodides have been used in alkylation reactions with nitrogen, oxygen and carbon nucleophiles. The nitrogen alkylation reactions are exemplified by the synthesis of the analgetics N-(1-/sup 11/C-ethyl)iodocaine and N-(1-/sup 11/C-butyl) bupivacaine. The synthesis of 3-nitrophenyl(1-/sup 11/C)propyl ether is also presented in this paper as an example of an oxygen alkylation.

  11. The synthesis of 1-11C-labelled ethyl, propyl, butyl and isobutyl iodides and examples of alkylation reactions

    International Nuclear Information System (INIS)

    Laangstroem, B.; Antoni, G.; Gullberg, P.; Halldin, C.; Naagren, K.; Rimland, A.; Svaerd, H.

    1986-01-01

    New 11 C-labelled precursors [1- 11 C]ethyl,[1- 11 C]propyl, [1- 11 C]butyl, and [1- 11 C]isobutyl iodides have been prepared by a 3-step reaction route using a one-pot system. The labelled iodides were obtained in 20-55#percent# radiochemical yields and 65-95#percent# radiochemical purities, with a total time for synthesis of the order of 10-14 min. The labelled iodides have been used in alkylation reactions with nitrogen, oxygen and carbon nucleophiles. The nitrogen alkylation reactions are exemplified by the synthesis of the analgetics N-[1- 11 C-ethyl]iodocaine and N-[1- 11 C-butyl] bupivacaine. The synthesis of 3-nitrophenyl[1- 11 C]propyl ether is also presented in this paper as an example of an oxygen alkylation. (author)

  12. Alpha-induced reactions on selenium between 11 and 15 MeV

    Science.gov (United States)

    Fiebiger, Stefan; Slavkovská, Zuzana; Giesen, Ulrich; Göbel, Kathrin; Heftrich, Tanja; Heiske, Annett; Reifarth, René; Schmidt, Stefan; Sonnabend, Kerstin; Thomas, Benedikt; Weigand, Mario

    2017-07-01

    The production of 77,79,85,85m Kr and 77Br via the reaction Se(α ,x) was investigated between {E}α =11 and 15 MeV using the activation technique. The irradiation of natural selenium targets on aluminum backings was conducted at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. The spectroscopic analysis of the reaction products was performed using a high-purity germanium detector located at PTB and a low energy photon spectrometer detector at the Goethe University Frankfurt, Germany. Thick-target yields were determined. The corresponding energy-dependent production cross sections of 77,79,85,85m Kr and 77Br were calculated from the thick-target yields. Good agreement between experimental data and theoretical predictions using the TALYS-1.6 code was found.

  13. 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

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

  15. Excitation of isomeric states 1h11/2 in (γ, n) reactions

    International Nuclear Information System (INIS)

    Tonchev, A.P.; Gangrskij, Yu.P.; Belov, A.G.

    1995-01-01

    The cross sections of (γ, n) reactions were measured for ground and isomeric states 1h 11/2 in 16 isotopes of Pd, Cd, Sn, Te, Ba, Ce, Nd and Sm. The energy of γ-rays was placed in the region of Giant Dipole Resonance. An activation method of measurements has been used. IR dependence of neutron and proton number in nucleus was detected and of excitation energy of residual nucleus as well. Different factors influencing the values of the isomeric ratios are discussed. 20 refs., 5 figs., 2 tabs

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

    International Nuclear Information System (INIS)

    Rainisch, R.

    2000-01-01

    The disposition of surplus plutonium inventories by the US Department of Energy (DOE) includes the immobilization of certain plutonium materials in a borosilicate glass matrix, also referred to as vitrification. This paper addresses source terms of plutonium masses immobilized in a borosilicate glass matrix where the glass components include both natural boron and enriched boron. The calculated source terms pertain to neutron and gamma source strength (particles per second), and source spectrum changes. The calculated source terms corresponding to natural boron and enriched boron are compared to determine the benefits (decrease in radiation source terms) for to the use of enriched boron. The analysis of plutonium glass source terms shows that a large component of the neutron source terms is due to (a, n) reactions. The Americium-241 and plutonium present in the glass emit alpha particles (a). These alpha particles interact with low-Z nuclides like B-11, B-10, and O-17 in the glass to produce neutrons. The low-Z nuclides are referred to as target particles. The reference glass contains 9.4 wt percent B 2 O 3 . Boron-11 was found to strongly support the (a, n) reactions in the glass matrix. B-11 has a natural abundance of over 80 percent. The (a, n) reaction rates for B-10 are lower than for B-11 and the analysis shows that the plutonium glass neutron source terms can be reduced by artificially enriching natural boron with B-10. The natural abundance of B-10 is 19.9 percent. Boron enriched to 96-wt percent B-10 or above can be obtained commercially. Since lower source terms imply lower dose rates to radiation workers handling the plutonium glass materials, it is important to know the achievable decrease in source terms as a result of boron enrichment. Plutonium materials are normally handled in glove boxes with shielded glass windows and the work entails both extremity and whole-body exposures. Lowering the source terms of the plutonium batches will make the handling

  17. A comparative study of two digestion methods employed for the determination boron in ferroboron used as an advanced shielding material

    International Nuclear Information System (INIS)

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

    2015-01-01

    Shielding of nuclear reactor core is an important requirement of fast reactors. An important objective of future Fast Breeder Reactors (FBRs) is to reduce the volume of shields. A large number of materials have been considered for use to reduce the neutron flux to acceptable levels. A shield material which brings down the energy of neutrons by elastic and inelastic scattering along with absorption will be more effective. Ferro boron is identified as one of the advanced shielding materials considered for use in future FBRs, planned to be constructed in India. Ferroboron is an economical and indigenously available material which qualifies as a promising shield material through literature survey and scoping calculations. Experiments have been conducted in KAMINI reactor to understand the effectiveness of prospective shield material Ferro-boron as an in-core shield material for future FBRs. The Ferro boron used in these experiments contained 11.8% and 15% of boron. Precise determination of boron content in these ferro boron samples is very important to determine its effectiveness as a shield material. In this work a comparative study was carried out to determine the boron content in ferro boron samples. In the first method the sample was treated with incremental amounts of nitric acid under reflux (to prevent rigorous reaction and volatalisation of boron). The solution was gradually heated and the solution was filtered through a Whatman Filter paper no. 41. The undissolved ferro boron residue collected in the filter paper after filtration, is transferred to a platinum crucible; mixed with sodium carbonate and is ashed. The crucible is placed over a burner for 1 h to fuse the contents. The fused mass is leached in dilute hydrochloric acid, added to the nitric acid filtrate and made up to pre-determined volume

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

    Directory of Open Access Journals (Sweden)

    MANISH GODARA

    2007-04-01

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

  19. Intermolecular Formation of Two C−C Bonds across Olefins Enabled by Boron-Based Relay Strategies

    Czech Academy of Sciences Publication Activity Database

    Hidasová, Denisa; Jahn, Ullrich

    2017-01-01

    Roč. 56, č. 33 (2017), s. 9656-9658 ISSN 1433-7851 Institutional support: RVO:61388963 Keywords : 1,2- metal ate rearrangement * C−C bond formation * radical reactions * transition metal catalysis * vinyl boronates Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 11.994, year: 2016

  20. Contribution to the study of the three-body reaction 11B (p,3α)

    International Nuclear Information System (INIS)

    Giorni, Alain

    1969-01-01

    The spectra of the 11 B (p,3α) reaction were measured with a two-parameters spectrometer at the proton energy of 680 keV, 1.4 and 2 MeV, corresponding at the 2 - , 1 - and 0 + level of 12 C. The spectra were compared with a calculation where we write the total amplitude ζ = τ + T G 0 τ for the reaction B 11 + p → α 1 + α 2 + α 3 , with G 0 = (E - H 0 + iε) -1 . The operator τ corresponds to the production of three un-correlated α; and the operator T = T 1 + T 2 + T 3 , [T i = t i + t i G 0 (T j + T k )], describing the 3α particles interaction is given by the Faddeev's equations. By a decomposition on the angular momentum and after symmetrization, we find the properties of the 3α system. The numerical calculations were made in the final state interaction approximation, i. e. T i ≅t i , where t is the two body αα amplitude given by the well known phase-shift δ 0 and δ 2 . The other neglected terms were estimated by a complex number. The resonant form of the excitation curve 11 B (p,3α) suggests to describe the matrix element of the τ matrix as a Breit-Wigner formula: = G i G f / (E - E 0 + i Γ 0 / 2), and for each 12 C level we have neglected the influence of the other resonance. The calculation gives a good description of the Dalitz-plot (excepted for the 0 + level of 12 C) if we assume that the contribution of the direct production term is negligible compared to the αα interaction terms. (author) [fr

  1. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    high temperature reaction between elemental boron and car- bon to form B4C is .... cible was used as the container for the electrolyte and also acted as an anode. ... chosen as cathode due to its availability, low cost, ease of fabrication and ...

  2. 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.

  3. Developments in boron magnetic resonance imaging (MRI)

    International Nuclear Information System (INIS)

    Schweizer, M.

    1995-01-01

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

  4. On the implementation of a chain nuclear reaction of thermonuclear fusion on the basis of the p+11B process

    Science.gov (United States)

    Belyaev, V. S.; Krainov, V. P.; Zagreev, B. V.; Matafonov, A. P.

    2015-07-01

    Various theoretical and experimental schemes for implementing a thermonuclear reactor on the basis of the p+11B reaction are considered. They include beam collisions, fusion in degenerate plasmas, ignition upon plasma acceleration by ponderomotive forces, and the irradiation of a solid-state target from 11B with a proton beam under conditions of a Coulomb explosion of hydrogen microdrops. The possibility of employing ultra-short high-intensity laser pulses to initiate the p+11B reaction under conditions far from thermodynamic equilibrium is discussed. This and some other weakly radioactive thermonuclear reactions are promising owing to their ecological cleanness—there are virtually no neutrons among fusion products. Nuclear reactions that follow the p+11B reaction may generate high-energy protons, sustaining a chain reaction, and this is an advantage of the p+11B option. The approach used also makes it possible to study nuclear reactions under conditions close to those in the early Universe or in the interior of stars.

  5. Synthesis of 1,1-Diphenylethylene (DPE): The Marriage of a Grignard Reaction and a Column Chromatography Experiment

    Science.gov (United States)

    Alty, Lisa T.; France, Marcia B.; Alty, Isaac G.; Saber, Christine A.; Smith, Donna M.

    2016-01-01

    The synthesis of 1,1-diphenylethylene (DPE) via a Grignard reaction, followed by an acid-catalyzed dehydration reaction, yields a mixture of compounds. DPE is a high boiling liquid that cannot be purified using simple distillation. However, it is easily separated from the more polar starting material and intermediate alcohol using both thin layer…

  6. Designing an Epithermal Neutron Beam for Boron Neutron Capture Therapy for the Fusion Reactions 2H(d,n)3He and 3H(d,n)4He1

    International Nuclear Information System (INIS)

    Verbeke, J.M.; Costes, S.V.; Bleuel, D.; Vujic, J.; Leung, K.N.

    1998-01-01

    A beam shaping assembly has been designed to moderate high energy neutrons from the fusion reactions 2 H(d,N) 3 He and 3 H(d,n) 4 He for use fin boron neutron capture therapy. The low neutron yield of the 2 H(d,n) 3 He reaction led to unacceptably long treatment times. However, a 160 mA deuteron beam of energy 400 keV led to a treatment time of 120 minutes with the reaction 3 H(d,n) 4 He. Equivalent doses of 9.6 Gy-Eq and 21.9 Gy-Eq to the skin and to a 8 cm deep tumor respectively have been computed

  7. Elastic enhancement factor in the 11B(p,n0)11C reaction at Ep=14.3 MeV

    International Nuclear Information System (INIS)

    Hussein, M.S.; Pessoa, E.F.; Schelin, H.R.; Carlson, B.V.; Douglas, R.A.

    1985-01-01

    The elastic enhancement factor in charge exchange reactions proceeding via the compound nucleus, predicted to attain the value of 2 in the weak isospin mixing regime by Harney, Weidenmuller and Richter five years ago, is tested here in the system 11 B(p,n) 11 C at = 14.3 MeV. Both the DWBA and Hauser-Feshbach calculations employed in the analysis are used in a way which physically simulates a two coupled-channels model. Our results show an enhancement factor larger than 1 indicating that isospin is mainly conserved in this reaction. (Author) [pt

  8. Selective on-line detection of boronic acids and derivatives in high-performance liquid chromatography eluates by post-column reaction with alizarin

    NARCIS (Netherlands)

    Duval, F.L.; Wardani, P.A.; Zuilhof, H.; Beek, van T.A.

    2015-01-01

    An on-line high-performance liquid chromatography (HPLC) method for the rapid and selective detection of boronic acids in complex mixtures was developed. After optimization experiments at an HPLC flow rate of 0.40 mL/min, the HPLC-separated analytes were mixed post-column with a solution of 75 µM

  9. Cross section of the {sup 11}B(n,p) {sup 11}Be reaction for 14.7-16.9 MeV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Stepancinc, B Z; Stanojevic, D M; Popic, V R; Aleksic, M R [Institute of nuclear sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

    1966-07-15

    The cross section of the {sup 11}B(n,p){sup 11}Be reaction was determined for neutron energy range from 14.7 to 16.9 MeV using the activation method. Activity measurements were done by using a coincidence spectrometer essentially consisting of two plastic scintillators. Energy dependent cross section values are presented together with the previously measured values for the energy range 14.5 - 16.9 MeV.

  10. Interaction cross section of 11Li + d reaction and the determination of nucleon density distribution in 11Li

    International Nuclear Information System (INIS)

    Tanihata, I.; Yoshida, K.; Suzuki, T.

    1992-01-01

    Interaction cross sections for 11 Li beams have been measured using p, d, and C targets at 800A and 400A MeV. The density distribution of the 11 Li nucleus has been determined, for the first time, combining interaction cross sections with various targets and energies. It was confirmed that only the distributions with long tails describe the observed data. (author)

  11. Synthesis of 1,1-Diborylalkenes through a Bronsted Base Catalyzed Reaction between Terminal Alkynes and Bis(pinacolato)diboron

    OpenAIRE

    Morinaga, Akira; Nagao, Kazunori; Ohmiya, Hirohisa; Sawamura, Masaya

    2015-01-01

    A method for the synthesis of 1,1-diborylalkenes through a Bronsted base catalyzed reaction between terminal alkynes and bis(pinacolato)diboron has been developed. The procedure allows direct synthesis of functionalized 1,1-diborylalkenes from various terminal alkynes including propiolates, propiolamides, and 2-ethynylazoles.

  12. Reliable set-up for in-loop 11C-carboxylations using Grignard reactions for the preparation of [carbonyl-11C]WAY-100635 and [11C]-(+)-PHNO

    International Nuclear Information System (INIS)

    Rami-Mark, Christina; Ungersboeck, Johanna; Haeusler, Daniela; Nics, Lukas; Philippe, Cecile; Mitterhauser, Markus; Willeit, Matthaeus; Lanzenberger, Rupert; Karanikas, Georgios; Wadsak, Wolfgang

    2013-01-01

    Aim of this work was the implementation of a generalized in-loop synthesis for 11 C-carboxylations and subsequent 11 C-acylations on the TRACERlab FxC Pro platform. The set-up was tested using [carbonyl- 11 C]WAY-100635 and, for the first time, [ 11 C]-(+)-PHNO. Its general applicability could be demonstrated and both [carbonyl- 11 C]WAY-100635 and [ 11 C]-(+)-PHNO were prepared with high reliability and satisfying outcome. - Highlights: • Generalized method for in-loop 11 C-carboxylations implemented. • Grignard reactions successfully tested. • First in-loop procedure for [ 11 C]-(+)PHNO established. • Satisfactory synthesis outcome for both [carbonyl- 11 C]WAY-100635 and [ 11 C]-(+)PHNO. • No distillation for purification of intermediate required

  13. One-nucleon transfer reactions induced by secondary beam of 11Be: study of the nuclear structure of the exotic nuclei 11Be and 10Li

    International Nuclear Information System (INIS)

    Pita, S.

    2000-09-01

    The structure of the neutron rich light nuclei 11 Be and 10 Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using 11 Be secondary beams. The 11 Be(p,d) 10 Be reaction bas been studied at 35.3 MeV/u. The 10 Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0 + 1 and 2 + 1 , states in 10 Be were measured up to θ CM = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation 10 Be 2+ in the 11 Be gs wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the 11 Be(d, 3 He) 10 Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus 10 Li. The energy spectrum was deduced from the 3 He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -S n = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p 1/2 shells in 10 Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the 11 Be(d,t) 10 Be reaction studied in the same experiment confirms the results obtained in the 11 Be(p,d) 10 Be reaction concerning the 11 Be gs structure. This work shows the interest and feasibility of studies of the shell properties of exotic nuclei using transfer reactions induced by radioactive beams and constitutes the beginning of a program

  14. Structure and distribution of cross-links in boron-modified phenol-formaldehyde resins designed for soft magnetic composites: a multiple-quantum 11B-11B MAS NMR correlation spectroscopy study

    Czech Academy of Sciences Publication Activity Database

    Kobera, Libor; Czernek, Jiří; Strečková, M.; Urbanová, Martina; Abbrent, Sabina; Brus, Jiří

    2015-01-01

    Roč. 48, č. 14 (2015), s. 4874-4881 ISSN 0024-9297 R&D Projects: GA MŠk(CZ) LD14010 Grant - others:European Commission(XE) COST Action MP1202 HINT Institutional support: RVO:61389013 Keywords : phenol-formaldehyde polymers * boron crosslinks * soft magnetic composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 5.554, year: 2015

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

    Energy Technology Data Exchange (ETDEWEB)

    Kitaoka, Y. [ed.

    1998-12-01

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

  16. 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

  17. Coupled-channels analyses for 9,11Li + 208Pb fusion reactions with multi-neutron transfer couplings

    Science.gov (United States)

    Choi, Ki-Seok; Cheoun, Myung-Ki; So, W. Y.; Hagino, K.; Kim, K. S.

    2018-05-01

    We discuss the role of two-neutron transfer processes in the fusion reaction of the 9,11Li + 208Pb systems. We first analyze the 9Li + 208Pb reaction by taking into account the coupling to the 7Li + 210Pb channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in 210Pb and solve the coupled-channels equations with the two channels. By adjusting the coupling strength and the effective Q-value, we successfully reproduce the experimental fusion cross sections for this system. We then analyze the 11Li + 208Pb reaction in a similar manner, that is, by taking into account three effective channels with 11Li + 208Pb, 9Li + 210Pb, and 7Li + 212Pb partitions. In order to take into account the halo structure of the 11Li nucleus, we construct the potential between 11Li and 208Pb with a double folding procedure, while we employ a Woods-Saxon type potential with the global Akyüz-Winther parameters for the other channels. Our calculation indicates that the multiple two-neutron transfer process plays a crucial role in the 11Li + 208Pb fusion reaction at energies around the Coulomb barrier.

  18. 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

  19. A study of the 10, 11B(p,n)10, 11C reactions between Ep=13,7 and 14,7 MeV

    International Nuclear Information System (INIS)

    Schelin, H.R.

    1985-01-01

    Using time-of-flight facilities of the Sao Paulo 8UD Pelletron Accelerator, absolute differential cross sections for the n 0 , n 1 , n 2 , n 3 , (n 4 +n 5 ), n 6 and n 7 groups for the reaction 11 B(p,n) 11 C and the n 0 and n 1 neutron groups for the reaction 10 B(p,n) 10 C have been measured at incident proton energies of 14.0, 14.3 and 14.6 MeV in the angular interval of 20 to 160 degrees. Excitation functions at θ lab =20 deg from Ep=13.7 to 14.7 MeV in intervals of 100 KeV were also measured. The theoretical analysis was conducted to determine relative contributions of the diret and compound nucleus processes in the differential cross sections. To this end, a two couple channel model model for the reactions was assumed. The DWBA model for the direct and the Hauser-Feshbch for the compound nucleus processes were in such a way as to simulate the exact coupled channels calculation through an appropriate choice of the absorption term W in the optical potential. The results indicate that about half of the cross section is due to the compound nucleus mechanism. The theoretical analysis aimed at obtaining the elastic enhancement factor for the channel 11 B(p,n 0 ) 11 C at Ep=14.3 MeV. This has been demonstrated to appear in compound nucleus charge reactions by Harney, Weidemueller and Richter and predicted to attain the value 2 when isospin is conserved. Our results show an enhancement factor larger than 1 indicating that isospin mixing is weak in this reaction. (Author) [pt

  20. Boron-isotope fractionation in plants

    Energy Technology Data Exchange (ETDEWEB)

    Marentes, E [Univ. of Guelph, Dept. of Horticultural Science, Guelph, Ontario (Canada); Vanderpool, R A [USDA/ARS Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota (United States); Shelp, B J [Univ. of Guelph, Dept. of Horticultural Science, Guelph, Ontario (Canada)

    1997-10-15

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

  1. Boron-isotope fractionation in plants

    International Nuclear Information System (INIS)

    Marentes, E.; Vanderpool, R.A.; Shelp, B.J.

    1997-01-01

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

  2. Cyclisation versus 1,1-Carboboration: Reactions of B(C6F5)3 with Propargyl Amides.

    Science.gov (United States)

    Melen, Rebecca L; Hansmann, Max M; Lough, Alan J; Hashmi, A Stephen K; Stephan, Douglas W

    2013-09-02

    A series of propargyl amides were prepared and their reactions with the Lewis acidic compound B(C6F5)3 were investigated. These reactions were shown to afford novel heterocycles under mild conditions. The reaction of a variety of N-substituted propargyl amides with B(C6F5)3 led to an intramolecular oxo-boration cyclisation reaction, which afforded the 5-alkylidene-4,5-dihydrooxazolium borate species. Secondary propargyl amides gave oxazoles in B(C6F5)3 mediated (catalytic) cyclisation reactions. In the special case of disubstitution adjacent to the nitrogen atom, 1,1-carboboration is favoured as a result of the increased steric hindrance (1,3-allylic strain) in the 5-alkylidene-4,5-dihydrooxazolium borate species. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Weak transitions in the quasi-elastic reaction 12C(e,e'p)11B

    International Nuclear Information System (INIS)

    Steenhoven, G. van der; Blok, H.P.; Vrije Univ., Amsterdam; Jans, E.; Lapikas, L.; Quint, E.N.M.; Witt Huberts, P.K.A. de

    1988-01-01

    In a high-resolution quasi-elastic 12 C(e,e'p) 11 B experiment several weak transitions have been observed to excited final states with spin and parity characteristic of direct knockout from orbitals above the 1p shell. The momentum distributions, which have been measured in parallel kinematics at an outgoing-proton energy of 70 MeV in the range of missing momentum - 170 ≤ p m ≤ 210 MeV/c, show the shape expected for a single-step knockout process. It is demonstrated that the interference between a direct-knockout process and a two-step process leading to the same final state in the (e,e'p) reaction may cause important modifications of the deduced spectroscopic factors. Explicit coupled-channels (CC) calculations show that the spectroscopic factor for the transition to the 7 - /2 state at 6.743 MeV is reduced by a factor of 6, whereas the spectroscopic factors of the other weak transitions observed in the present experiment are uncertain by a factor of 2 due to CC-effects. Since the strength of these transitions is larger than can be explained by a pure two-step process, we interpret the observation of these transitions as direct evidence for the existence of ground-state correlations in 12 C. The total spectroscopic strength in the E x region between 6 and 12 MeV amounts to 0.1, or 4.1% of the observed strength for 1p knockout in the low E x region. Two peaks have been identified in the missing-energy spectrum that hitherto have not been reported: A narrow peak at E x =9.82 (3) MeV with an l=0 character and a broad structure centered at about 11.5 MeV with an l=1 character. The missing-energy spectrum between E x =12 and 24 MeV corresponding to 1s 1/2 knockout has also been analyzed. The deduced momentum distribution shows evidence for the onset of a two-nucleon mechanism beyond the two-particle emission threshold. (orig.)

  4. Probing the direct step of relativistic heavy ion fragmentation: (12C, 11B+p) at 2.1 GeV/nucleon with C and CH2 targets

    International Nuclear Information System (INIS)

    Webb, M.L.

    1987-06-01

    Relativistic heavy ion collisions may be classified as central (and near central), peripheral, and grazing with each collision type producing different proton and other charged projectile fragment scattering mechanisms and characteristics. This report focuses on peripheral and grazing collisions in the fragmentation of Carbon-12 into Boron-11 and a proton, testing models of the kinetics involved in this reaction. The data were measured at the Heavy Ion Superconducting Spectrometer (HISS) at Lawrence Berkeley Laboratory and include excitation energy for the p/Boron-11 pair, and rapidity versus transverse momentum for protons and Boron-11. 58 refs., 35 figs., 8 tabs

  5. Application of drug delivery system to boron neutron capture therapy for cancer.

    Science.gov (United States)

    Yanagië, Hironobu; Ogata, Aya; Sugiyama, Hirotaka; Eriguchi, Masazumi; Takamoto, Shinichi; Takahashi, Hiroyuki

    2008-04-01

    Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons ((10)B + (1)n --> (7)Li + (4)He (alpha) + 2.31 MeV (93.7 %)/2.79 MeV (6.3 %)). The resulting lithium ions and alphaparticles are high linear energy transfer (LET) particles which give a high biological effect. Their short range in tissue (5 - 9 mum) restricts radiation damage to those cells in which boron atoms are located at the time of neutron irradiation. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer and hepatoma. Sodium mercaptoundecahydro-dodecaborate (Na(2)(10)B(12)H(11)SH: BSH) and borono-phenylalanine ((10)BPA) are currently being used in clinical treatments. These low molecule compounds are easily cleared from cancer cells and blood, so high accumulation and selective delivery of boron compounds into tumor tissues and cancer cells are most important to achieve effective BNCT and to avoid damage to adjacent healthy cells. In order to achieve the selective delivery of boron atoms to cancer cells, a drug delivery system (DDS) is an attractive intelligent technology for targeting and controlled release of drugs. We performed literature searches related to boron delivery systems in vitro and in vivo. We describe several DDS technologies for boron delivery to cancer tissues and cancer cells from the past to current status. We are convinced that it will be possible to use liposomes, monoclonal antibodies and WOW emulsions as boron delivery systems for BNCT clinically in accordance with the preparation of good commercial product (GCP) grade materials.

  6. The B-10((p)over-right-arrow, gamma)C-11 reaction at astrophysically relevant energies

    NARCIS (Netherlands)

    Tonchev, AP; Nelson, SO; Sabourov, K; Crowley, BT; Joshi, K; Weller, HR; Kelley, JH; Prior, RM; Spraker, M; Kalantar-Nayestanaki, N

    2003-01-01

    The B-10(, gamma)C-11 reaction was studied by detecting the gamma-rays produced when 100, 130-, and 160-keV polarized protons were stopped in a thick B-10 target. Polarized and unpolarized incident beams were used to measure the cross section and vector analyzing power as a function of angle and

  7. 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)

  8. Aspects of the chemistry of boron

    International Nuclear Information System (INIS)

    Moellinger, H.

    1976-01-01

    Crystal phases of elementary boron are reviewed as well as boron-sulphur, boron-selenum, boron-tellurium, and boron-nitrogen compounds, carboranes, and boron-carbohydrate complexes. A boron cadastre of rivers and lakes serves to illustrate the role of boron in environmental protection. Technically relevant boron compounds and their uses are mentioned. (orig.) 891 HK/orig. 892 MB [de

  9. Study of the excited levels of 11C and 12C by the analysis of protons induced reactions

    International Nuclear Information System (INIS)

    Rihet, Y.

    1984-07-01

    The present work is a study of 11 and 12 C excited states by reactions of non polarised protons on 10 B and 11 B. R-matrix analysis of the 10 B excitation curves in the range E p = 0 to 8 MeV was used to establish parameters of 41 levels in 11 C. Isobaric multiplets of T = 1/2 and T = 3/2 states in A = 11 nuclei are deduced. Analysis of 11 B excitation curves in the E p = 0.5 to 7.4 MeV range led to parameter values of 60 levels in 12 C. T = 1 states in A = 12 isobaric nuclei are discussed [fr

  10. Contribution to the study of 12C excited levels resulting from the reactions 11B (P/ α0) and 11B (p, α1)

    International Nuclear Information System (INIS)

    Longequeue, J.P.

    1963-11-01

    This work is made up of two parts. In the first part the differential cross-sections have been determined of the reactions 11 B (p,α) from 130 to 500 keV thus confirming, at the 163 keV resonance, the (2 + ) characteristics of the 16.11 MeV level of 12 C. Furthermore, the experimental results in the neighbourhood of the 163 keV resonance can be explained by the interference of the 12 C levels: 2 + at 16.11 MeV and 1 - at 17.23 MeV for the α 0 , 2 + at 16.11 MeV and 2 - at 16.58 MeV for the α 1 . In the second part the (α -8Be ) disintegration process of 12 C has been studied in the neighbourhood of the 16.11 MeV level. It is shown that, if the (α -8Be ) mode of disintegration is preponderant outside the E p = 163 keV resonance, it is also preponderant at this same resonance; a direct disintegration of the 12 C to 3 α, with an approximate magnitude of 40 per cent has however not been excluded. (author) [fr

  11. 11

    African Journals Online (AJOL)

    a routine working week. Special ... day of the working week and retested after finishing work on ... 4. 3. Med. 11,8. 12. -ye. 0. 5. 5. Med. 27,3. 107. -ye. 2. 6. 6. Med. 17,1. 80. -Ye. 0. 7. 3 .... present hours after first exposure (e.g. at night), it is also.

  12. 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 ...

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

    International Nuclear Information System (INIS)

    Yanez S, J.C.

    1994-01-01

    Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10 7 n/cm 2 s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author)

  14. Dosimetry boron neutron capture therapy in liver cancer (hepatocellular carcinoma) by means of MCNP-code with neutron source from thermal column

    International Nuclear Information System (INIS)

    Irhas; Andang Widi Harto; Yohannes Sardjono

    2014-01-01

    Boron Neutron Capture Therapy (BNCT) using physics principle when B 10 (Boron-10) irradiated by low energy neutron (thermal neutron). Boron and thermal neutron reaction produced B 11m (Boron-11m) (t 1/2 =10 -2 s). B 11m decay emitted alpha, Li 7 (Lithium-7) particle and gamma ray. Irradiated time needed to ensure cancer dose enough. Liver cancer was primary malignant who located in liver (Hepatocellular carcinoma). Malignant in liver were different to metastatic from Breast, Colon Cancer, and the other. This condition was Metastatic Liver Cancer. Monte Carlo method used by Monte Carlo N-Particle (MCNP) Software. Probabilistic approach used for probability of interaction occurred and record refers to characteristic of particle and material. In this case, thermal neutron produced by model of Collimated Thermal Column Kartini Research Nuclear Reactor, Yogyakarta. Modelling organ and source used liver organ that contain of cancer tissue and research reactor. Variation of boron concentration was 20, 25, 30, 35, 40, 45, and 47 µg/g cancers. Output of MCNP calculation were neutron scattering dose, gamma ray dose and neutron flux from reactor. Neutron flux used to calculate alpha, proton and gamma ray dose from interaction of tissue material and thermal neutron. Variation of boron concentration result dose rate to every variation were 0,059; 0,072; 0,084; 0,098; 0.108; 0,12; 0,125 Gy/sec. Irradiation time who need to every concentration were 841,5 see (14 min 1 sec); 696,07 sec(11 min 36 sec); 593.11 sec (9 min 53 sec); 461,35 sec (8 min 30 sec); 461,238 sec (7 min 41 sec); 414,23 sec (6 min 54 sec); 398,38 sec (6 min 38 sec). Irradiating time could shortly when boron concentration more high. (author)

  15. Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma

    International Nuclear Information System (INIS)

    Labaune, C.; Baccou, C.; Loisel, G.; Yahia, V.; Depierreux, S.; Goyon, C.; Rafelski, J.

    2013-01-01

    The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments. (authors)

  16. The study of high-boron steel and high-boron cast iron used for shield

    International Nuclear Information System (INIS)

    Pan Xuerong; Lu Jixin; Wen Yaozeng; Wang Zhaishu; Cheng Jiantin; Cheng Wen; Shun Danqi; Yu Jinmu

    1996-12-01

    The smelting, forging, heat-treatment technology and the mechanical properties of three kinds of high-boron steels (type 1: 0.5% boron; type 2: 0.5% boron and 4% or 2% nickel; type 3: 0.5% boron, 0.5% nickel and 0.5% molybdenum) were studied. The test results show that the technology for smelting, forging and heat-treatment (1050 degree C/0.5 h water cooled + 810 degree C/1 h oil cooled) in laboratory is feasible. Being sensitive to notch, the impact toughness of high-boron steel type 1 is not steady and can not meet the technology requirements on mechanical properties. The mechanical properties of both high-boron steel type 2 and type 3 can meet the technological requirements. The smelting technology of high-boron casting iron containing 0.5% boron was researched. The tests show that this casting iron can be smelted in laboratory and its properties can basically satisfy the technology requirements. (10 refs., 6 figs., 11 tab.)

  17. One-nucleon transfer reactions induced by secondary beam of {sup 11}Be: study of the nuclear structure of the exotic nuclei {sup 11}Be and {sup 10}Li; Reactions de transfert d'un nucleon induites par un faisceau secondaire de {sup 11}Be: etude de la structure des noyaux exotiques {sup 11}Be et {sup 10}Li

    Energy Technology Data Exchange (ETDEWEB)

    Pita, S

    2000-09-01

    The structure of the neutron rich light nuclei {sup 11}Be and {sup 10}Li has been investigated by means of one nucleon transfer reactions. The experiments have been carried out at GANIL in inverse kinematics using {sup 11}Be secondary beams. The {sup 11}Be(p,d){sup 10}Be reaction bas been studied at 35.3 MeV/u. The {sup 10}Be ejectiles were analyzed by the spectrometer SPEG, and coincident deuterons were detected in the position sensitive silicon detector CHARISSA. Transfer cross sections to 0{sup +}{sub 1} and 2{sup +}{sub 1}, states in {sup 10}Be were measured up to {theta}{sub CM} = 16 deg. and compared to DWBA and CRC predictions. The effects of neutron-cure couplings on reaction form factors have been studied by solving coupled equations in the framework of a vibrational model. It is shown that the rate of core excitation {sup 10}Be{sub 2+} in the {sup 11}Be{sub gs} wave function is overestimated by a standard analysis with form factors given by the usual Separation Energy prescription. The former model predicts a rate of core excitation of 16% and leads to theoretical cross sections which are in good agreement with the experimental data. The aim of the {sup 11}Be(d,{sup 3}He){sup 10}Li experiment, realized at 37 MeV/u, was to measure the distribution of the 2s neutron strength in the unbound nucleus {sup 10}Li. The energy spectrum was deduced from the {sup 3}He energy and angle measured by the silicon strip detector array MUST. An asymmetric peak is clearly observed near the threshold, with a maximum at -S{sub n} = 130 keV. This constitutes a direct proof of the inversion of 2s and 1p{sub 1/2} shells in {sup 10}Li, which was until now a controversial question in spite of many experimental efforts. On the other band the analysis of the {sup 11}Be(d,t){sup 10}Be reaction studied in the same experiment confirms the results obtained in the {sup 11}Be(p,d){sup 10}Be reaction concerning the {sup 11}Be{sub gs} structure. This work shows the interest and feasibility

  18. Synthesis and characterization of ammonium phosphate fertilizers with boron

    Directory of Open Access Journals (Sweden)

    ANGELA MAGDA

    2010-07-01

    Full Text Available The concentration of boron, an essential micronutrient for plants, presents a narrow range between deficiency and toxicity. In order to provide the boron requirement for plants, and to avoid toxicity problems, boron compounds are mixed with basic fertilizers. Sodium borate pentahydrate was used as a boron source. Ammonium orthophosphates fertilizers with boron were prepared by neutralizing phosphoric acid with ammonia and addition of variable amounts of sodium tetraborate pentahydrate to the reaction mixture at a NH3:H3PO4 molar ratio of 1.5. The fertilizers obtained with boron contents ranging from 0.05 to 1 % (w/w were fully characterized by chemical analysis, thermal analysis, X-ray diffraction and infrared spectrophotometry. The studies showed that up to 500 °C, regardless of the boron content, no significant changes concerning thermal stability and nutritional properties occurred. Above 500 °C, an increase of thermal stability with an increase of the boron content was observed. X-Ray diffraction of a heat-treated sample containing 5 % (w/w boron indicated the appearance of boron orthophosphate, BPO4, as a new crystalline phase, and the disappearance of the previous structures above 500 °C, which explains the increase in thermal stability.

  19. Study of induced reactions by a secondary beam of 11Be in Be, Ti and Au targets

    International Nuclear Information System (INIS)

    Dogny, S.

    1992-01-01

    In the last decade, new phenomena arised from nuclear reaction studies of neutron-rich light nuclei produced by projectile fragmentation. In this work, first we will recall briefly some aspects of these studies, in particular the two-neutron halo for nuclei whose binding energy of the two last neutrons is low. Secondly, we will describe the experiment which aims to study 11 Be reactions on Be, Ti and Be targets. The results of this experiment show the presence of a one-neutron halo, corresponding to a high dissociation cross-section for the three targets. We will show that three mechanisms, Coulomb dissociation for heavy targets, diffraction-and absorption-dissociation for light targets, account satisfactorily for reactions leading to 10 Be

  20. A 11-Steps Total Synthesis of Magellanine through a Gold(I)-Catalyzed Dehydro Diels-Alder Reaction.

    Science.gov (United States)

    McGee, Philippe; Bétournay, Geneviève; Barabé, Francis; Barriault, Louis

    2017-05-22

    We have developed an innovative strategy for the formation of angular carbocycles via a gold(I)-catalyzed dehydro Diels-Alder reaction. This transformation provides rapid access to a variety of complex angular cores in excellent diastereoselectivities and high yields. The usefulness of this Au I -catalyzed cycloaddition was further demonstrated by accomplishing a 11-steps total synthesis of (±)-magellanine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The R-matrix investigation of 8Li(α, n)11B reaction below 6 MeV

    Science.gov (United States)

    Kilic, Ali Ihsan; Muecher, Dennis; Garret, Paul; Svensson, Carl

    2017-09-01

    The investigation of cross sections for the 8Li(α, n)11B reaction has important impact for both primordial nucleosynthesis in the inhomogeneous models as well as constraining the physical conditions characterizing the r-process. However, there are large discrepancies existing between inclusive and exclusive measurements of the cross section below 3 MeV. The R-Matrix technique is a powerful tool for the analysis of the nuclear data for the purpose of extracting level information of compound nucleus 12B and extrapolation of the astrophysical S-Factor to Gamow energies. We have applied the R-matrix calculations for the 8Li(α, n)11B reaction and will present results for both the reaction rates and the partial S-factor. Combining the direct reaction contribution with the results from our R-matrix calculations, we can well describe the experimental data from the inclusive measurements. However, new experiments are needed in order to understand the role of neutron detection close to the threshold, for which we describe our experimental plans at ISAC, TRIUMF, using the newly developed DESCANT array.

  2. Nuclear structure effects in fusion-fission of compound systems 20,21,22Ne formed in 10,11B+10,11B reactions

    International Nuclear Information System (INIS)

    Singh, BirBikram; Kaur, Manpreet; Kaur, Varinderjit; Gupta, Raj K.

    2014-01-01

    The dynamical cluster-decay model (DCM) of Gupta and collaborators has been successfully applied to the decay of number of hot and rotating compound nuclei in different mass regions, formed in low-energy heavy ion reactions. Recently, its application to the binary symmetric decay (BSD) of very light mass compound systems 20,21,22 Ne formed in 10,11 B+ 10,11 B reactions at E lab =48 MeV is extended, as the experimental data for σ BSD Expt . is available, namely, for 20 Ne (∼ 270 mb), 21 Ne ( 22 Ne ( BSD DCM for the BSD of the three Ne systems is calculated, comprising fusion-fission σ ff and deep inelastic scattering/orbiting σorb contributions (evaluated empirically here) from compound nucleus CN and non-compound nucleus nCN processes, respectively. The significant observation from this study is that, of the total σ BSD DCM , σ ff contribution is very strong for the decay of 20 Ne (=195.270 mb; >70%), followed by 21 Ne (=65.723 mb; ∼50%) and 22 Ne (=8.677 mb; almost 10%). This means that the process of collective clusterization within the DCM is playing very strong role for the decay of 20 Ne

  3. Large animal normal tissue tolerance with boron neutron capture.

    Science.gov (United States)

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

    1994-03-30

    Normal tissue tolerance of boron neutron capture irradiation using borocaptate sodium (NA2B12H11SH) in an epithermal neutron beam was studied. Large retriever-type dogs were used and the irradiations were performed by single dose, 5 x 10 dorsal portal. Fourteen dogs were irradiated with the epithermal neutron beam alone and 35 dogs were irradiated following intravenous administration of borocaptate sodium. Total body irradiation effect could be seen from the decreased leukocytes and platelets following irradiation. Most values returned to normal within 40 days postirradiation. Severe dermal necrosis occurred in animals given 15 Gy epithermal neutrons alone and in animals irradiated to a total peak physical dose greater than 64 Gy in animals following borocaptate sodium infusion. Lethal brain necrosis was seen in animals receiving between 27 and 39 Gy. Lethal brain necrosis occurred at 22-36 weeks postirradiation. A total peak physical dose of approximately 27 Gy and blood-boron concentrations of 25-50 ppm resulted in abnormal magnetic resonance imaging results in 6 months postexamination. Seven of eight of these animals remained normal and the lesions were not detected at the 12-month postirradiation examination. The bimodal therapy presents a complex challenge in attempting to achieve dose response assays. The resultant total radiation dose is a composite of low and high LET components. The short track length of the boron fission fragments and the geometric effect of the vessels causes much of the intravascular dose to miss the presumed critical target of the endothelial cells. The results indicate a large dose-sparing effect from the boron capture reactions within the blood.

  4. Large animal normal tissue tolerance with boron neutron capture

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  5. Study of heavy ion fusion reaction of 58Ni + 24Mg at 11 MeV/nucleon

    International Nuclear Information System (INIS)

    Shea, J.Y.

    1991-01-01

    This thesis presents a study of the heavy ion fusion reaction in which a 58 Ni projectile bombards a 24 Mg target at 11 MeV/nucleon. The incident projectile energy was purposefully chosen so as the system studied to be at the onset of the more complex and interesting phenomenon of incomplete fusion. The physics motivation is to probe the central collision of a heavy, energetic, and asymmetric system by means of both inclusive and exclusive experimental measurements. The experiment was performed at HHIRF (Holifield Heavy Ion Research Facility) by using the coupled accelerators at Oak Ridge National Laboratory. The reaction products were measured by the new open-quotes HILI-Ringclose quotes large solid angle detector system at Oak Ridge National Laboratory. The thesis discusses the physics motivation and the systematics of heavy ion fusion reactions. Details of the design and construction of a new CsI(T1) Ring detector is given. Since this is the first such study performed on the Heavy Ion Light Ion (HILI) detector, an extensive discussion of the calibration procedures and the data reduction methods are given. The fusion reaction data were analyzed in both inclusive and exclusive modes with the result that a valuable new perspective on the deconvolution of the reaction mechanism has been achieved

  6. ISOBORDAT: An Online Data Base on Boron Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Pennisi, M.; Adorni-Braccesi, A.; Andreani, D.; Gori, L.; Gonfiantini, R. [Istituto di Geoscienze e Georisorse, CNR, Pisa (Italy); Sciuto, P. F. [Servizio Geologico, Sismico e dei Suoli, D.G. Ambiente e Difesa del Suolo e della Costa, Regione Emilia Romagna, Bologna (Italy)

    2013-07-15

    From 1986, boron isotope data in natural substances increased sharply in scientific publications. Analytical difficulties derived from complex geochemical matrices have been faced and interlaboratory calibrations reported in the boron literature. Boron isotopes are nowdays applied to investigate boron origin and migration in natural waters, sources of boron contamination, water-rock interactions and also contribute to water resource management. This is especially important in those areas where boron content exceeds the local regulations for drinking water supply and boron sources need to be identified. ISOBORDAT, an interactive database on boron isotope composition and content in natural waters is presented to the wider community of boron isotope users. The database's structure, scope and applications are reported, along with a discussion on {delta}{sup 11}B values obtained in Italian waters. In the database boron data are structured in the following categories: rainwater, rivers, lakes, groundwater and potential contaminants. New categories (medium and high enthalpy fluids from volcanic and geothermal areas) are anticipated. ISOBORDAT aims to be as interactive as possible and will be developed taking into account information and suggestions received. The database is continually undergoing revision to keep pace with continuous data publication. Indications of data that are missing at present are greatly appreciated. (author)

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

    International Nuclear Information System (INIS)

    Yanagie, Hironobu; Takahashi, Hiroyuki

    2010-01-01

    Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between 10 B and thermal neutrons ( 10 B+ 1 n → 7 Li+ 4 He (α) +2.31 MeV (93.7%)/2.79 MeV (6.3%)). The resulting lithium ions and αparticles are high linear energy transfer (LET) particles which give high biological effect. Their short range in tissue (5-9 μm) restricts radiation damage to those cells in which boron atoms are located at the time of neutron irradiation. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer and hepatoma etc, recently. Sodium borocaptate (Na 2 10 B 12 H 11 SH; BSH) and borono-phenylalanine ( 10 BPA) are currently being used in clinical treatments. To achieve the selective delivery of boron atoms to cancer cells, drug delivery system (DDS) becomes an attractive intelligent technology as targeting and controlled release of drugs. We have firstly reported that 10 B atoms delivered by immunoliposomes are cytotoxic to human pancreatic carcinoma cells (AsPC-1) after thermal neutron irradiation in vitro. The intra-tumoural injection of boronated immunoliposomes can increase the retention of 10 B atoms in tumour cells, causing suppression of tumour growth in vivo following thermal neutron irradiation. We prepared polyethylene-glycol binding liposomes (PEG-liposomes) as an effective 10 B carrier to obviate phagocytosis by reticuloendotherial systems. We had prepared 10 BSH entrapped Water-in-Oil-in-Water (WOW) emulsion. The 10 B concentration in VX-2 tumour after intra-arterial injection of 10 BSH entrapped WOW emulsion was superior to the groups of 10 BSH entrapped conventional Lipiodol mix emulsion. 10 Boron entrapped WOW emulsion is one of the most useful for intra-arterial boron delivery carrier on BNCT to hepatocellular carcinoma. (author)

  8. Reaction of Diazo Compounds with Difluorocarbene: An Efficient Approach towards 1,1-Difluoroolefins.

    Science.gov (United States)

    Zhang, Zhikun; Yu, Weizhi; Wu, Chenggui; Wang, Chengpeng; Zhang, Yan; Wang, Jianbo

    2016-01-04

    A transition-metal-free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF2 Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. The chemoselective formal carbene dimerization reaction is achieved owing to the electronic properties and the relative stability of the difluorocarbene intermediate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Double-step processes in the 12C(p,d)11C reaction at 45 MeV

    International Nuclear Information System (INIS)

    Couvert, Pierre.

    1974-01-01

    12 C(p,d) 11 C pick-up reaction was performed with a 45 MeV proton beam. A 130keV energy resolution was obtained and angular distributions of nine of the ten first levels of 11 C have been extracted within a large angular range. Assuming only neutron direct transfert, the strong relative excitation of high spin levels cannot be reproduced by a DWBA analysis. The double-step process assumption seems to be verified by a systematical analysis of the (p,d) reaction mechanisms. This analysis is done in the coupled-channel formalism for the five first negative parity states of 11 C. The 3/2 - ground state is essentially populated by the direct transfer of a Psub(3/2) neutron. The contribution of a double-step process, via the 2 + inelastic excitation of 12 C, is important for the four other states. A mechanism which assumes a deuteron inelastic scattering on the 11 C final nucleus after the neutron transfer cannot be neglected and improves the fits when it is taken into account [fr

  10. Field-controlled electron transfer and reaction kinetics of the biological catalytic system of microperoxidase-11 and hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Yongki Choi

    2011-12-01

    Full Text Available Controlled reaction kinetics of the bio-catalytic system of microperoxidase-11 and hydrogen peroxide has been achieved using an electrostatic technique. The technique allowed independent control of 1 the thermodynamics of the system using electrochemical setup and 2 the quantum mechanical tunneling at the interface between microperoxidase-11 and the working electrode by applying a gating voltage to the electrode. The cathodic currents of electrodes immobilized with microperoxidase-11 showed a dependence on the gating voltage in the presence of hydrogen peroxide, indicating a controllable reduction reaction. The measured kinetic parameters of the bio-catalytic reduction showed nonlinear dependences on the gating voltage as the result of modified interfacial electron tunnel due to the field induced at the microperoxidase-11-electrode interface. Our results indicate that the kinetics of the reduction of hydrogen peroxide can be controlled by a gating voltage and illustrate the operation of a field-effect bio-catalytic transistor, whose current-generating mechanism is the conversion of hydrogen peroxide to water with the current being controlled by the gating voltage.

  11. Oxidation of boron carbide at high temperatures

    International Nuclear Information System (INIS)

    Steinbrueck, Martin

    2005-01-01

    The oxidation kinetics of various types of boron carbides (pellets, powder) were investigated in the temperature range between 1073 and 1873 K. Oxidation rates were measured in transient and isothermal tests by means of mass spectrometric gas analysis. Oxidation of boron carbide is controlled by the formation of superficial liquid boron oxide and its loss due to the reaction with surplus steam to volatile boric acids and/or direct evaporation at temperatures above 1770 K. The overall reaction kinetics is paralinear. Linear oxidation kinetics established soon after the initiation of oxidation under the test conditions described in this report. Oxidation is strongly influenced by the thermohydraulic boundary conditions and in particular by the steam partial pressure and flow rate. On the other hand, the microstructure of the B 4 C samples has a limited influence on oxidation. Very low amounts of methane were produced in these tests

  12. Cross section measurements of the 10B(d,n0)11C reaction below 160 keV

    International Nuclear Information System (INIS)

    Stave, S.; Ahmed, M. W.; Blackston, M. A.; Crowell, A. S.; Henshaw, S. S.; Howell, C. R.; Kingsberry, P.; Perdue, B. A.; Weller, H. R.; Antolak, A. J.; Doyle, B. L.; Rossi, P.; Prior, R. M.; Spraker, M. C.

    2008-01-01

    New data were taken at the Triangle Universities Nuclear Laboratory to investigate the plausibility of using low energy deuterons and the 10 B(d,n) 11 C reaction as a portable source of 6.3 MeV neutrons. Analysis of the data at and below incident deuteron energies of 160 keV indicates an n 0 neutron cross section that is lower than previous estimates by at least three orders of magnitude. In separate runs, deuterons with two different energies (160 and 140 keV) were stopped in a 10 B target. The resulting n 0 neutrons of approximately 6.3 MeV were detected at angles between 0 deg. and 150 deg. The angle integrated yields were used to determine the astrophysical S factor for this reaction assuming a constant value for the S factor below 160 keV. The cross sections reported between 130 and 160 keV were calculated using the extracted value of the S factor. The measured n 0 cross section is several orders of magnitude smaller than previous results, thus eliminating 10 B(d,n) 11 C as a portable source of intense neutrons with low energy deuteron beams on the order of tens of microamps. In order to gain insight into the reaction dynamics at these low energies the cross section results have been compared with results from calculations using the distorted wave Born approximation (DWBA) and a detailed Hauser-Feshbach calculation performed by the authors. The angular distribution is consistent with the Hauser-Feshbach calculation suggesting a statistical compound nucleus reaction rather than a direct reaction

  13. Hydrolytic Stability of Boronate Ester-Linked Covalent Organic Frameworks

    KAUST Repository

    Li, Huifang; Li, Haoyuan; Dai, Qingqing; Li, Hong; Bredas, Jean-Luc

    2018-01-01

    by reducing the energy barrier by a factor of 3. Importantly, the hydrolysis of boronate ester bonds situated in a COF environment follows reaction pathways that are different and have increased energy barriers. These results point to an enhanced hydrolytic

  14. Tritium release from fast neutron irradiated boron carbide

    International Nuclear Information System (INIS)

    Hollenberg, G.W.

    1977-01-01

    A high-energy neutron reaction with boron produces tritium. In the LMFBR control material, B 4 C, most of the tritium that is generated remains in the pellets. Potential retention mechanisms are discussed. 5 figures

  15. 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

  16. Structure of the excited states of {sup 11}Be reached through the reaction d({sup 10}Be,p){sup 11}Be; Structure des etats du {sup 11}Be excites par la reaction d({sup 10}Be,p){sup 11}Be

    Energy Technology Data Exchange (ETDEWEB)

    Delaunay, F

    2003-10-01

    The one-neutron transfer reaction d({sup 10}Be,p){sup 11}Be has been studied at 32 A.MeV at GANIL with a {sup 10}Be secondary beam. Protons were detected by the silicon strip array MUST. The ground state and excited states of {sup 11}Be at 0.32, 1.78 and 3.41 MeV were populated, demonstrating the feasibility of transfer reactions induced by radioactive beams leading to bound and unbound states. A DWBA (distorted wave born approximation) analysis indicates for the 3.41 MeV state spin and parity 3/2{sup +} or 5/2{sup +} and a spectroscopic factor of 0.18 or 0.11, respectively. A broad structure centered at 10 MeV is also observed and corresponds to transfer to the 1d sub-shells. If one assumes that only the 1d3/2 orbital contributes to this structure, the splitting of the 1d neutron states in {sup 11}Be is estimated to be 6.3 MeV. Using a 2-particle-RPA (random phase approximation) model, we have shown that neutron-neutron correlations play an important role in the inversion between the 2s1/2 and 1p1/2 neutron states in {sup 11}Be. (author)

  17. 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

  18. 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

  19. Boron-Doped Carbon Nano-/Microballs from Orthoboric Acid-Starch: Preparation, Characterization, and Lithium Ion Storage Properties

    Directory of Open Access Journals (Sweden)

    Xinhua Lu

    2018-01-01

    Full Text Available A boron-doped carbon nano-/microballs (BC was successfully obtained via a two-step procedure including hydrothermal reaction (180°C and carbonization (800°C with cheap starch and H3BO3 as the carbon and boron source. As a new kind of boron-doped carbon, BC contained 2.03 at% B-content and presented the morphology as almost perfect nano-/microballs with different sizes ranging from 500 nm to 5 μm. Besides that, due to the electron deficient boron, BC was explored as anode material and presented good lithium storage performance. At a current density of 0.2 C, the first reversible specific discharge capacity of BC electrode reached as high as 964.2 mAh g–1 and kept at 699 mAh g–1 till the 11th cycle. BC also exhibited good cycle ability with a specific capacity of 356 mAh g–1 after 79 cycles at a current density of 0.5 C. This work proved to be an effective approach for boron-doped carbon nanostructures which has potential usage for lithium storage material.

  20. Boronization in TEXTOR

    International Nuclear Information System (INIS)

    Winter, J.; Esser, H.G.; Koenen, L.; Reimer, H.; Seggern, J. v.; Schlueter, J.; Waelbroeck, F.; Wienhold, P.; Veprek, S.

    1989-01-01

    The liner and limiters of TEXTOR have been coated in situ with a boron containing carbon film using a RG discharge in a throughflow of 0.8 He + 0.1 B 2 H 6 + 0.1 CH 4 . The average film thickness was 30-50 nm, the ratio of boron and carbon in the layer was about 1:1 according to Auger Electron Spectroscopy. Subsequent tokamak discharges are characterized by a small fraction of radiated power ( eff lower than 1.2 are derived from conductivity measurements. The most prominent change in the impurity concentration compared to good conditions in a carbonized surrounding is measured for oxygen. The value OVI/anti n e of the OVI intensity normalized to the averaged plasma density anti n e decreases by more than a factor of four. The decrease in the oxygen content manifests itself also as a reduction of the CO and CO 2 partial pressures measured during and after the discharge with a sniffer probe. The carbon levels are reduced by a factor of about two as measured by the normalized intensity CII/anti n e of the CII line and via the ratio of the C fluxes and deuterium fluxed measured at the limiter (CI/D α ). The wall shows a pronounced sorption of hydrogen from the plasma, easing the density control and the establishment of low recycling conditions. The beneficial conditions did not show a significant deterioration during more than 200 discharges, including numerous shots at ICRH power levels >2 MW. (orig.)

  1. Chemical surface reactions by click chemistry: coumarin dye modification of 11-bromoundecyltrichlorosilane monolayers

    International Nuclear Information System (INIS)

    Haensch, Claudia; Hoeppener, Stephanie; Schubert, Ulrich S

    2008-01-01

    The functionalization of surfaces and the ability to tailor their properties with desired physico-chemical functions is an important field of research with a broad spectrum of applications. These applications range from the modification of wetting properties, over the alteration of optical properties, to the fabrication of molecular electronic devices. In each of these fields, it is of specific importance to be able to control the quality of the layers with high precision. The present study demonstrates an approach that utilizes the 1,3-dipolar cycloaddition of terminal acetylenes to prepare triazole-terminated monolayers on different substrates. The characterization of the precursor monolayers, the optimization of the chemical surface reactions as well as the clicking of a fluorescent dye molecule on such azide-terminated monolayers was carried out. A coumarin 343 derivative was utilized to discuss the aspects of the functionalization approach. Based on this approach, a number of potential surface reactions, facilitated via the acetylene-substituted functional molecules, for a broad range of applications is at hand, thus leading to numerous possibilities where surface modifications are concerned. These modifications can be applied on non-structured surfaces of silicon or glass or can be used on structured surfaces. Various possibilities are discussed

  2. The search for molecular effects in range corrections: boron determination by proton bombardment

    International Nuclear Information System (INIS)

    Olivier, C.; Peisach, M.

    1985-01-01

    Three different nuclear reactions viz. 10 B(p,αγ) 7 Be, 10 B(p,p,'γ) 10 B, and 11 B(p,p'γ) 11 B were used to analyse 21 pure boron compounds and mixtures of known composition by prompt gamma-ray spectrometry under proton bombardment. Elemental stopping powers were calculated from tables and used to compute the stopping power of the target matrices by Bragg's Law. Apparent discrepancies in the measured yield could point to deviations from Bragg's Law and hence to molecular effects. The maximum value for any molecular effect was found to be < 8,3%

  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. Boron-doped manganese dioxide for supercapacitors.

    Science.gov (United States)

    Chi, Hong Zhong; Li, Yuwei; Xin, Yingxu; Qin, Haiying

    2014-11-11

    The addition of boron as a dopant during the reaction between carbon fiber and permanganate led to significant enhancement of the growth-rate and formation of the porous framework. The doped MnO2 was superior to the pristine sample as electrode materials for supercapacitors in terms of the specific capacitance and rate capability.

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

    Science.gov (United States)

    Bedasso, Eyrusalam Kifyalew

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

  6. Helium behaviour in implanted boron carbide

    Directory of Open Access Journals (Sweden)

    Motte Vianney

    2015-01-01

    Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

  7. Investigations in anhydrous liquid ammonia. Reaction of group 2, 4, 5, 11 metal and actinoids compounds

    International Nuclear Information System (INIS)

    Woidy, Patrick

    2014-01-01

    The solubility and reactivity of metal halides, transition metal halides, and actinoid halides in liquid ammonia can lead to new starting materials for the synthesis of fluorides in low oxidation states or for nitrides via a ''low-temperature route''. In this context the ability of metal and actinoid halides to act as an acceptor for or donor of fluoride ions is also of interest. Four different systems were investigated in this study. In the first section, the synthesis and characterization of new compounds were carried out in the system CuX/NH 3 (X = F, Cl, Br, I, and CN) and lead to a ligand stabilized monovalent copper fluoride as a main result. In the second section, the solubility of uranyl compounds and uranium halides in liquid ammonia was investigated and the products were characterized. In the third section, alkali metal thorates were synthesized. Their solubility in liquid ammonia and their behavior as an acceptor for fluoride ions was investigated. In the last section, the results on the solubility behavior of transition metal halides in liquid ammonia and their coordination behavior are presented. In the first system CuX/NH 3 several new compounds, such as [Cu(NH 3 ) 3 ]X (X = Br, I or CN) were synthesized and characterized. The reactions of this compounds with fluoride ion donors (NH 4 F or Me 4 NF) led unfortunately not to the monovalent copper fluoride CuF. The comproportionation reaction of Cu and CuF 2 in liquid ammonia lead to the compounds [Cu(NH 3 ) 3 ] 2 [Cu 2 (NH 3 ) 2 ] . 4 NH 3 and [Cu(NH 3 ) 2 ]F . NH 3 . For the preparation of binary CuF, various decomposition experiments were executed on the compound [Cu(NH 3 ) 2 ]F . NH 3 which resulted in different decomposition products. In additional studies various complexes of divalent copper was investigated and with the compound [Cu(NH 3 ) 5 ]F 2 . NH 3 the solubility of fluoride containing substances in liquid ammonia could be shown. Studies of six- and tetravalent uranium

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

    International Nuclear Information System (INIS)

    Chiba, Akio; Suzuki, Yasutaka; Goto, Sumitaka; Saito, Yukio; Jinbo, Ryutaro; Ogiwara, Norio; Saido, Masahiro.

    1996-01-01

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

  9. Effect of Contact Time on Interface Reaction between Aluminum Silicon (7% and 11% Alloy and Steel Dies SKD 61

    Directory of Open Access Journals (Sweden)

    Bambang Suharno

    2010-10-01

    Full Text Available Die soldering (die sticking is a defect of metal casting in which molten metal “welds” to the metallic die mold surface during casting process. Die soldering is the result of an interface reaction between the molten aluminum and the die material. Aluminum alloy with 7 and 11% silicon and SKD 61 die steel are the most common melt and die material used in aluminum die casting. This research is done to study the morphology and the characteristics of the formed AlxFeySiz intermetallic layer during interface reaction at dipping test. The samples of as-anneal SKD 61 tool steel was dipped into the molten of Al-7%Si held at temperature 680oC and into molten Al-11%Si held at temperature 710oC with the different contact time of 10 minutes; 30 minutes; and 50 minutes. The research results showed that the interface reaction can form a compact intermetallic layer with AlxFey phase and a broken intermetallic layer with AlxFeySiz phase on the surface of SKD 61 tool steel. The increasing of the contact time by the immersion of material SKD 61 tool steel in both of molten Al-7%Si and Al-11%Si will increase the thickness of the AlxFeySiz intermetallic layer until an optimum point and then decreasing. The micro hardness of the AlxFeySiz intermetallic layer depends on the content of the iron. Increasing of the iron content in intermetallic layer will increase the micro hardness of the AlxFeySiz. This condition happened because the increasing of Fe content will cause forming of intermetallic AlxFeySiz phase becomes quicker.

  10. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  11. Search for 4H, 5H and 6H nuclei in the 11B-induced reaction on 9Be

    International Nuclear Information System (INIS)

    Belozerov, A.V.; Borcea, C.; Dlouhy, Z.

    1985-01-01

    In the 11 B(88.0 MeV)+ 9 Be reaction the energy spectra of the 14 O, 15 O and 16 O nuclei have been measured to obtain some information about their partners in the exit channel - the neutron-rich hydrogen isotopes 4 H, 5 H and 6 H. The unbound levels in the 4 H and 6 H systems have been observed at excitation energies of 3.5 +- 0.5 MeV (GITA approximately 1 MeV) and 2.6 +- 0.5 MeV (GITA=1.5 +- 0.3 MeV), respectively

  12. Boron neutron capture therapy. Synthesis of boronated amines- and DNA intercalating agents for potential use in cancer therapy

    International Nuclear Information System (INIS)

    Ghaneolhosseini, H.

    1998-01-01

    Boron Neutron Capture Therapy is a binary cancer treatment modality, involving the delivery of a suitable boron compound to tumour cells followed by irradiation of the tumour by thermal neutrons. Boronated agents can selectively be delivered to tumour cells either directly with tumour-specific boron compounds, or by use of targeting strategies. However, the efficacy of this method would increase if the boron agents are localised in the cell nucleus rather than in the cell cytoplasm when neutron irradiation takes place. With these considerations in mind, some boronated DNA intercalating/interacting agents such as phenanthridine- acridine- spermidine- and naphthalimide derivatives were synthesised. Aminoalkyl-o-carboranes were synthesised in order to be used both for coupling to macromolecules and also for halogenation of their corresponding nido-derivatives. The amino groups were introduced using the Gabriel reagent N, N-dibenzyl iminodicarboxylate to provide 1-(aminomethyl)- and 1-(2-aminoethyl)-o-carboranes. The first attempt to achieve the possibility to accumulate a higher concentration of boron atoms in the cell nucleus was to synthesize carboranyl phenanthridinium analogues by reacting a p- or o-carboranyl moiety with phenanthridine, a chromophore with a planar aromatic ring system as DNA intercalator. Boronated acridine-spermidine, boronated diacridine, and boronated dispermidine were obtained in order to increase water solubility to avoid the interaction of these agents with non-DNA sides of the cell, especially membranes; and to enhance the feasibility of a higher DNA-binding constant and also decrease the DNA-drug dissociation rate. Finally, the synthesis of a boronated naphthalimide derivative was carried out by nucleophilic reaction of a primary aminoalkyl-p-carborane with naphthalic anhydride. Biological evaluations on DNA-binding, toxicity, and cellular binding with carboranyl phenanthridinium analogues, boronated acridine- and spermidine are described

  13. Spectrographic determination of boron and silicon in uranium tetrafluoride: Study of the chemical reactions in the electrode cavity when ZnO is used as a uranium excitation suppressor; Determinacion espectrografica de Boro y Silicio en Tetrafluoruro de Unraio: Estudio de las reacciones quimicas que tienen lugar en el crater del electrodo al autilizar ZnO como supresor de la excitacion del Uranio

    Energy Technology Data Exchange (ETDEWEB)

    Alduan, F. A.; Capdevila, C.; Rosa, M.

    1973-07-01

    A method has been developed for determining traces of boron and silicon in uranium tetrafluoride. Use is made of zinc oxide to decrease the volatilization of uranium and achieve high sensitivities. The thermochemical reactions which occur in the anode cavity during the arcing process have been investigated. UO{sub 2} and a uranium, zinc and fluorine compound, both less volatile than uranium tetrafluoride, are formed. (Author)

  14. One-step synthesis of shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond as efficient electrocatalyst for the oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Liu, Xiaoxu; Wang, Yanhui; Dong, Liang; Chen, Xi; Xin, Guoxiang; Zhang, Yan; Zang, Jianbing

    2016-01-01

    Shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond (BN-C/ND) non-noble metal catalyst has been synthesized by a simple one-step heat-treatment of the mixture with nanodiamond, melamine, boric acid and FeCl 3 . In the process of the surface graphitization of nanodiamond with catalysis by FeCl 3 , B and N atoms from the decomposition of boric acid and melamine were directly introduced into the graphite lattice to form B, N co-doped graphitic carbon shell, while the core still retained the diamond structure. Electrochemical measurements of the BN-C/ND catalyst show much higher electrocatalytic activities towards oxygen reduction reaction (ORR) in alkaline medium than its analogues doped with B or N alone (B-C/ND or N-C/ND). The high catalytic activity of BN-C/ND is attributed to the synergetic effect caused by co-doping of C/ND with B and N. Meanwhile, the BN-C/ND exhibits an excellent electrochemical stability due to the special shell/core structure. There is almost no alteration occurred in the cyclic voltammetry measurements for BN-C/ND before and after 5000 cycles. All experimental results prove that the BN-C/ND may be exploited as a potentially efficient and inexpensive non-noble metal cathode catalyst for ORR to substitute Pt-based catalysts in fuel cells.

  15. Boron determination in tourmaline by neutron induced radiography

    Energy Technology Data Exchange (ETDEWEB)

    Qureshi, A.A. E-mail: aaqureshi@pinstech.org.pk; Akram, M.; Ayub Khan, M.; Khattak, N.U.; Qureshi, I.E.; Khan, H.A

    2001-06-01

    The technique of neutron induced radiography has been applied to determine the boron concentration and its spatial distribution in mineral tourmaline collected from Swat Tourmaline Granite, Northern Pakistan. The technique involves the simultaneous irradiation of sample and a standard fixed on a track detector with thermal neutrons and the counting of alpha and {sup 7}Li tracks produced in the detector from the nuclear reaction {sup 10}B(n,{alpha}){sup 7}Li. Boron concentration is determined by comparing the {sup 7}Li and alpha particle tracks density with that of a standard of known boron concentration. Boron concentration in tourmaline has been found to be (3.40{+-}0.01)% in this study which is on the upper side within the normal range (2.5-3.8)% reported in the world. The presence of somewhat higher concentration of boron in tourmaline indicates that the Swat Tourmaline Granite was generated as a late stage hydrothermal activity during the Himalayan Orogeny.

  16. Nuclear magnetic resonance spectroscopy of boron compounds containing two-, three- and four-coordinate boron

    International Nuclear Information System (INIS)

    Wrackmeyer, B.

    1988-01-01

    The influence of boron chemistry on various areas of research in inorganic, organic and theoretical chemistry is well documented. In fact, many models presently employed to describe chemical bonding in general can be traced to attempts to understand bonding in boranes. The confirmation of many theoretical predictions in boron chemistry relies on direct and indirect structural information provided by various physical methods that - fortunately - became available almost at the same rate as that with which the interest in boron compounds was growing. Clearly, there has always been a strong link between the interest in synthesis and the application of physical methods. As in many other areas of chemistry, developments in boron chemistry have been greatly accelerated by NMR. 11 B NMR has been at the center of interest from the beginning, accompanied by routine 1 H NMR measurements, and occasional 14 N, 19 F and 31 P NMR work. In the last 12 years, we have seen an increasing number of 13 C NMR studies of boron compounds. The availability of multinuclear facilities for PFT NMR spectrometers stimulates the measurement of the NMR spectra of other nuclei, like 29 Si, 119 Sn or other metals, in order to obtain additional information. This paper is intended to serve several purposes: to update previous reviews on 11 B NMR of boron compounds, to demonstrate some applications of multinuclear NMR to boron chemistry; to attempt to incorporate new NMR parameters into the known data set; and to summarize the experimental facts required for obtaining the maximum information from NMR studies on boron compounds

  17. 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.

  18. Impact of impregnation with boron compounds on combustion ...

    African Journals Online (AJOL)

    user

    2011-04-11

    Apr 11, 2011 ... 2Gazi University, Industrial Arts Education Faculty, Department of ... security. Key words: Combustion, flame retardance, coatings, boron compounds, varnish. ..... attack in wood deterioration and its prevention by preservative.

  19. Nuclear reactions with 11C and 14O radioactive ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Fanqing [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    Radioactive ion beams (RIBs) have been shown to be a useful tool for studying proton-rich nuclides near and beyond the proton dripline and for evaluating nuclear models. To take full advantage of RIBs, Elastic Resonance Scattering in Inverse Kinematics with Thick Targets (ERSIKTT), has proven to be a reliable experimental tool for investigations of proton unbound nuclei. Following several years of effort, Berkeley Experiments with Accelerated Radioactive Species (BEARS), a RIBs capability, has been developed at the Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The current BEARS provides two RIBs: a 11C beam of up to 2x108 pps intensity on target and an 14O beam of up to 3x104 pps intensity. While the development of the 11C beam has been relatively easy, a number of challenges had to be overcome to obtain the 14O beam. The excellent 11C beam has been used to investigate several reactions. The first was the 197Au(11C,xn)208-xnAt reaction, which was used to measure excitation functions for the 4n to 8n exit channels. The measured cross sections were generally predicted quite well using the fusion-evaporation code HIVAP. Possible errors in the branching ratios of ?? decays from At isotopes as well as the presence of incomplete fusion reactions probably contribute to specific overpredictions. 15F has been investigated by the p(14O,p)14O reaction with the ERSIKTT technology. Several 14O+p runs have been performed. Excellent energy calibration was obtained using resonances from the p(14N,p)14N reaction in inverse kinematics, and comparing the results to those obtained earlier with normal kinematics. The differences between 14N+p and 14O+p in the stopping power function have been evaluated for better energy calibration. After careful calibration, the energy levels of 15F

  20. 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

  1. 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)

  2. Boron tolerance in NS wheat lines

    Directory of Open Access Journals (Sweden)

    Brdar Milka

    2006-01-01

    Full Text Available Boron is an essential micronutrient for higher plants. Present in excessive amounts boron becomes toxic and can limit plant growth and yield. Suppression of root growth is one of the symptoms of boron toxicity in wheat. This study was undertaken to investigate the response of 10 perspective NS lines of wheat to high concentrations of boron. Analysis of root growth was done on young plants, germinated and grown in the presence of different concentrations of boric acid (0, 50,100 and 150 mg/1. Significant differences occurred between analyzed genotypes and treatments regarding root length. Average suppression of root growth was between 11,6 and 34,2%, for line NS 252/02 are even noted 61,4% longer roots at treatments in relation to the control. Lines with mean suppression of root growth less than 20% (NS 101/02, NS 138/01, NS 53/03 and NS 73/02 may be considered as boron tolerant. Spearmans coefficients showed high level of agreement regarding rang of root length for genotypes treated with 100 and 150 mg H3BO3/l.

  3. An overview the boron dilution issue in PWRs

    International Nuclear Information System (INIS)

    Hyvaerinen, J.

    1994-01-01

    The presentation is an overview of boron (boric acid) dilution in pressurized water reactors (PWRs). Boric acid has been widely used in PWRs as a dissolved poison, as one of the main reactivity controlling means, for a long time, from nearly but not quite from the beginning of the design, construction and operation of PWRs in the present-day sense. The specific safety issue, namely the risk of uncontrolled reactivity insertion due to inadvertent boron dilution, is discussed first, followed by a brief look on the history of boron usage in PWRs. A discussion of boron dilution phenomenology is presented next in general terms. Some particular concerns that boron dilution phenomena arouse in the minds of a regulator will also be presented before concluding with a brief look on the future of dissolved poisons. (11 refs.)

  4. Magnetic substate populations of product nuclei in the /sup 11/B(d,p)/sup 12/B reaction

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, M; Ochi, S; Minamisono, T; Mizobuchi, A; Sugimoto, K [Osaka Univ., Toyonaka (Japan). Lab. of Nuclear Studies

    1976-05-31

    Magnetic substate populations of product nuclei in the /sup 11/B(d,p)/sup 12/B reaction have been measured in an energy range Esub(d) = 1.3-3.0 MeV at recoil angles of thetasub(R) = 55/sup 0/, 45/sup 0/ and 27/sup 0/-37/sup 0/. A static magnetic field (3 kG) was applied normal to the reaction plane to keep the nuclear orientation. Quadrupole effects on the implanted /sup 12/B in Ta were utilized to perturb the Zeeman splitting. NMR transitions were induced, and detected by the asymmetry change in the ..beta..-decay of /sup 12/B. From this information, the magnetic substate populations were determined, for the unique assignment of which the sign of the quadrupole interaction had to be known. For this purpose, a p-..gamma.. angular correlation was measured, which determined the alignment of the first excited state of /sup 12/B. A comparison of the present result with theoretical predictions is given, together with the resultant information about j-mixings in the /sup 12/B states.

  5. Joining of boron carbide using nickel interlayer

    International Nuclear Information System (INIS)

    Vosughi, A.; Hadian, A. M.

    2008-01-01

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

  6. Boron complexing with H-resorcinol and acidic hydroxyxanthene dyes

    International Nuclear Information System (INIS)

    Nazarenko, V.A.; Flyantikova, G.V.; Chekirda, T.N.

    1984-01-01

    Complex formation of boron with H-resorcinol (hr; 2,4-dihydroxybenzene-azo -8-hydroxynaphtalene-3,6-disulfonic acid) and acidic hydroxyxanthene dyes (hxd: fluorescein, eosine, erathrosine). Mixed-ligand complexes with a ratio of r:hr:hxd=1:1:1 are formed at pH=5-6. The chemism of the complex formation of boron with H-resorcinol and fluorescein has been studied. The stability consta nt of the complex is 1.12x10 21 , the conditional molar absorptivitis 1.80x10 0 . This complex formation reaction was used for photometric determination of boron in natural water

  7. Contribution to the study of {sup 12}C excited levels resulting from the reactions {sup 11}B (P/ {alpha}{sub 0}) and {sup 11}B (p, {alpha}{sub 1}); Contribution a l'etude des niveaux excites du {sup 12}C obtenus par les reactions {sup 11}B (p, {alpha}{sub 0}) et {sup 11}B (p, {alpha}{sub l})

    Energy Technology Data Exchange (ETDEWEB)

    Longequeue, J P [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-11-15

    This work is made up of two parts. In the first part the differential cross-sections have been determined of the reactions {sup 11}B (p,{alpha}) from 130 to 500 keV thus confirming, at the 163 keV resonance, the (2{sup +}) characteristics of the 16.11 MeV level of {sup 12}C. Furthermore, the experimental results in the neighbourhood of the 163 keV resonance can be explained by the interference of the {sup 12}C levels: 2{sup +} at 16.11 MeV and 1{sup -} at 17.23 MeV for the {alpha}{sub 0}, 2{sup +} at 16.11 MeV and 2{sup -} at 16.58 MeV for the {alpha}{sub 1}. In the second part the ({alpha}{sup -8Be}) disintegration process of {sup 12}C has been studied in the neighbourhood of the 16.11 MeV level. It is shown that, if the ({alpha}{sup -8Be}) mode of disintegration is preponderant outside the E{sub p} = 163 keV resonance, it is also preponderant at this same resonance; a direct disintegration of the {sup 12}C to 3 {alpha}, with an approximate magnitude of 40 per cent has however not been excluded. (author) [French] Ce travail comprend deux parties: Dans la premiere, on a determine la section efficace differentielle des reactions {sup 11}B (p,{alpha}) de 130 a 500 keV, confirmant, a la resonance de 163 keV, les caracteristiques (2{sup +}) du niveau de 16,11 MeV du {sup 12}C. En outre, les resultats experimentaux au voisinage de la resonance de 163 keV sont explicables par l'interference des niveaux du {sup 12}C: 2{sup +} a 16,11 MeV et 1{sup -} a 17,23 MeV pour les {alpha}{sub 0}, 2{sup +} a 16,11 MeV et 2{sup -} a 16,58 MeV pour les {alpha}{sub 1}. Dans la deuxieme partie, on a etudie le mode de desintegration ({alpha}{sup -8Be}) du {sup 12}C au voisinage du niveau de 16,11 MeV. On a montre que, si le mode de desintegration ({alpha}{sup -8Be}) est preponderant en dehors de la resonance E{sub p} = 163 keV, il est egalement preponderant a cette resonance; une desintegration directe en 3{alpha} du {sup 12}C, dont l'ordre de grandeur maximum serait de 40 pour cent, n

  8. Stability of boron-doped graphene/copper interface: DFT, XPS and OSEE studies

    Science.gov (United States)

    Boukhvalov, D. W.; Zhidkov, I. S.; Kukharenko, A. I.; Slesarev, A. I.; Zatsepin, A. F.; Cholakh, S. O.; Kurmaev, E. Z.

    2018-05-01

    Two different types of boron-doped graphene/copper interfaces synthesized using two different flow rates of Ar through the bubbler containing the boron source were studied. X-ray photoelectron spectra (XPS) and optically stimulated electron emission (OSEE) measurements have demonstrated that boron-doped graphene coating provides a high corrosion resistivity of Cu-substrate with the light traces of the oxidation of carbon cover. The density functional theory calculations suggest that for the case of substitutional (graphitic) boron-defect only the oxidation near boron impurity is energetically favorable and creation of the vacancies that can induce the oxidation of copper substrate is energetically unfavorable. In the case of non-graphitic boron defects oxidation of the area, a nearby impurity is metastable that not only prevent oxidation but makes boron-doped graphene. Modeling of oxygen reduction reaction demonstrates high catalytic performance of these materials.

  9. Experimental study of bound states in 12Be through low-energy 11Be(d,p)-transfer reactions

    DEFF Research Database (Denmark)

    Johansen, Jacob S.; Bildstein, V.; Borge, M. J. G.

    2013-01-01

    The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium arra...

  10. Application of the boron autoradiography in structural steels

    International Nuclear Information System (INIS)

    Azevedo, A.L.T. de

    1984-01-01

    The development of boron containing steels requires a knowledge of the microstructural state of that element, determined by the competition between precipitation and solution.An example of the use of the autoradiographic method for obtaining boron distribution images is described and showed. The technique is based on an α emitting nuclear reaction, which leaves a latent track in cellulose. This detector material is revealed by chemical etching and observed by optical and electron transmission microscopy. (Author) [pt

  11. 3M"T"M neutron quench. Compounds with substantial water solubility and boron content

    International Nuclear Information System (INIS)

    Cook, Kevin S.; Blake, Alex B.; Neef, C. Jody

    2014-01-01

    Of the two naturally occurring isotopes of boron ("1"1B 80%, "1"0B 20%), "1"0B is a good neutron absorber with a thermal neutron absorption cross section of ∼3800 barns. The ability to absorb thermal neutrons while producing benign reaction products makes boron an ideal atom to aid in the control and arrest of the fission reaction in nuclear power reactors. In current practice, boric acid and sodium pentaborate are commonly used as neutron absorbers in the water regime of active and passive safety systems. 3M"T"M Neutron Quench compounds have been developed to be applied in situations where criticality control needs exceed normal control methods. In this type of situation these compounds have several advantages over commonly used neutron absorbers like boric acid: Boron Content; compounds contain up to 80 wt% boron compared to 16 wt% for boric acid and sodium pentaborate. Solubility; >16 g B/100 g solution compared to 0.6 g B/100 g solution for boric acid at 25°C. pH neutrality; compounds demonstrate pH neutrality even in concentrated solutions. Thermal Stability; Compounds are stable as solids at temperatures greater than 500°C. Corrosiveness; Electrochemical corrosion rate studies have indicated that these compounds are significantly less corrosive than boric acid. Use of 3M"T"M Neutron Quench can lead to reduction in emergency shutdown pool size, reduce or remove the necessity for pool heating and heat tracing of lines, allow for more rapid introduction of the absorber in emergency situations or be used in other applications where significant neutron control is necessary. (author)

  12. Shock Response of Boron Carbide

    National Research Council Canada - National Science Library

    Dandekar, D. P. (Dattatraya Purushottam)

    2001-01-01

    .... The present work was undertaken to determine tensile/spall strength of boron carbide under plane shock wave loading and to analyze all available shock compression data on boron carbide materials...

  13. Neutron dosimetry in boron neutron capture therapy

    International Nuclear Information System (INIS)

    Fairchild, R.G.; Miola, U.J.; Ettinger, K.V.

    1981-01-01

    The recent development of various borated compounds and the utilization of one of these (Na 2 B 12 H 11 SH) to treat brain tumors in clinical studies in Japan has renewed interest in neutron capture therapy. In these procedures thermal neutrons interact with 10 B in boron containing cells through the 10 B(n,α) 7 Li reaction producing charged particles with a maximum range of approx. 10μm in tissue. Borated analogs of chlorpromazine, porphyrin, thiouracil and deoxyuridine promise improved tumor uptake and blood clearance. The therapy beam from the Medical Research Reactor in Brookhaven contains neutrons from a modified and filtered fission spectrum and dosimetric consequences of the use of the above mentioned compounds in conjunction with thermal and epithermal fluxes are discussed in the paper. One of the important problems of radiation dosimetry in capture therapy is determination of the flux profile and, hence, the dose profile in the brain. This has been achieved by constructing a brain phantom made of TE plastic. The lyoluminescence technique provides a convenient way of monitoring the neutron flux distributions; the detectors for this purpose utilize 6 Li and 10 B compounds. Such compounds have been synthesized specially for the purpose of dosimetry of thermal and epithermal beams. In addition, standard lyoluminescent phosphors, like glutamine, could be used to determine the collisional component of the dose as well as the contribution of the 14 N(n,p) 14 C reaction. Measurements of thermal flux were compared with calculations and with measurements done with activation foils

  14. 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

  15. Structural Evolution under Reaction Conditions of Supported (NH43HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

    Directory of Open Access Journals (Sweden)

    Fangli Jing

    2015-03-01

    Full Text Available When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH43HPMo11VO40 (APMV catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Various techniques, such as TGA/DTG (Thermo-Gravimetric Analysis/Derivative Thermo-Gravimetry, H2-TPR (Temperature Programed Reduction, in situ XRD (X-Ray Diffraction and XPS (X-ray Photoelectron Spectroscopy, were applied. It was clearly evidenced that the thermal stability and the reducibility of the Keggin units are improved by supporting 40% APMV active phase on Cs3PMo12O40 (CPM. The partial degradation of APMV takes place depending on temperature and reaction conditions. The decomposition of ammonium cations (releasing NH3 leads to the formation of vacancies favoring cationic exchanges between vanadium coming from the active phase and cesium coming from the support. In addition, the vanadium expelled from the Keggin structure is further reduced to V4+, species, which contributes (with Mo5+ to activate isobutane. The increase in reducibility of the supported catalyst is assumed to improve the catalytic performance in comparison with those of unsupported APMV.

  16. Measurement of the 12C(e,e‧p)11B two-body breakup reaction at high missing momentum

    Science.gov (United States)

    Monaghan, P.; Shneor, R.; Subedi, R.; Anderson, B. D.; Aniol, K.; Annand, J.; Arrington, J.; Benaoum, H. B.; Benmokhtar, F.; Bertin, P.; Bertozzi, W.; Boeglin, W.; Chen, J. P.; Choi, Seonho; Chudakov, E.; Ciofi degli Atti, C.; Cisbani, E.; Cosyn, W.; Craver, B.; de Jager, C. W.; Feuerbach, R. J.; Folts, E.; Frullani, S.; Garibaldi, F.; Gayou, O.; Gilad, S.; Gilman, R.; Glamazdin, O.; Gomez, J.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Ibrahim, H.; Igarashi, R.; Jans, E.; Jiang, X.; Kaufman, L.; Kelleher, A.; Kolarkar, A.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Liyanage, N.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; Mazouz, M.; Meekins, D.; Michaels, R.; Moffit, B.; Morita, H.; Nanda, S.; Perdrisat, C. F.; Piasetzky, E.; Potokar, M.; Punjabi, V.; Qiang, Y.; Reinhold, J.; Reitz, B.; Ron, G.; Rosner, G.; Ryckebusch, J.; Saha, A.; Sawatzky, B.; Segal, J.; Shahinyan, A.; Širca, S.; Slifer, K.; Solvignon, P.; Sulkosky, V.; Thompson, N.; Ulmer, P. E.; Urciuoli, G. M.; Voutier, E.; Wang, K.; Watson, J. W.; Weinstein, L. B.; Wojtsekhowski, B.; Wood, S.; Yao, H.; Zheng, X.; Zhu, L.

    2014-10-01

    The five-fold differential cross section for the 12C{{(e,{{e}^{\\prime }}p)}^{11}}B reaction was determined over a missing momentum range of 200-400 MeV\\;{{c}^{-1}}, in a kinematics regime with {{x}_{B}}\\gt 1 and {{Q}^{2}}=2.0 {{(GeV\\;{{c}^{-1}})}^{2}}. A comparison of the results with previous lower missing momentum data and with theoretical models are presented. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV\\;{{c}^{-1}}. The theoretical calculations are from two very different approaches, one mean field and the other short range correlated; yet for this system the two approaches show striking agreement with the data and each other up to a missing momentum value of 325 MeV\\;{{c}^{-1}}. For larger momenta, the calculations diverge which is likely due to the factorization approximation used in the short range approach.

  17. Implantation of boron in silicon

    International Nuclear Information System (INIS)

    Hofker, W.K.

    1975-01-01

    The distribution versus depth of boron implanted in silicon and the corresponding electrical activity obtained after annealing are studied. The boron distributions are measured by secondary-ion mass spectrometry. Boron distributions implanted at energies in the range from 30 keV to 800 keV in amorphous and polycrystalline silicon are analysed. Moments of these distributions are determined by a curve-fitting programme and compared with moments calculated by Winterbon. Boron distributions obtained by implantations along a dense crystallographic direction in monocrystalline silicon are found to have penetrating tails. After investigation of some possible mechanisms of tail formation it is concluded that the tails are due to channelling. It was found that the behaviour of boron during annealing is determined by the properties of three boron fractions consisting of precipitated boron, interstitial boron and substitutional boron. The electrical activity of the boron versus depth is found to be consistent with the three boron fractions. A peculiar redistribution of boron is found which is induced by the implantation of a high dose of heavy ions and subsequent annealing. Different mechanisms which may cause the observed effects, such as thermal diffusion which is influenced by lattice strain and damage, are discussed. (Auth.)

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

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Søtofte, Inger

    2002-01-01

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

  19. Chemical erosion of sintered boron carbide due to H+ impact

    International Nuclear Information System (INIS)

    Davis, J.W.; Haasz, A.A.

    1990-06-01

    The production of hydrocarbons and boron hydrides due to H + bombardment of sintered B 4 C has been investigated as a function of sample temperature and incident ion energy. While hydrocarbon production was observed, the yields were approximately two orders of magnitude smaller than observed for graphite. There was no evidence to indicate the production of any volatile boron-containing compounds. (3 figs., 11 refs.)

  20. Structure and single-phase regime of boron carbides

    International Nuclear Information System (INIS)

    Emin, D.

    1988-01-01

    The boron carbides are composed of twelve-atom icosahedral clusters which are linked by direct covalent bonds and through three-atom intericosahedral chains. The boron carbides are known to exist as a single phase with carbon concentrations from about 8 to about 20 at. %. This range of carbon concentrations is made possible by the substitution of boron and carbon atoms for one another within both the icosahedra and intericosahedral chains. The most widely accepted structural model for B 4 C (the boron carbide with nominally 20% carbon) has B/sub 11/C icosahedra with C-B-C intericosahedral chains. Here, the free energy of the boron carbides is studied as a function of carbon concentration by considering the effects of replacing carbon atoms within B 4 C with boron atoms. It is concluded that entropic and energetic considerations both favor the replacement of carbon atoms with boron atoms within the intericosahedral chains, C-B-C→C-B-B. Once the carbon concentration is so low that the vast majority of the chains are C-B-B chains, near B/sub 13/C 2 , subsequent substitutions of carbon atoms with boron atoms occur within the icosahedra, B/sub 11/C→B/sub 12/. Maxima of the free energy occur at the most ordered compositions: B 4 C,B/sub 13/C 2 ,B/sub 14/C. This structural model, determined by studying the free energy, agrees with that previously suggested by analysis of electronic and thermal transport data. These considerations also provide an explanation for the wide single-phase regime found for boron carbides

  1. RDH13L, an enzyme responsible for the aldehyde-alcohol redox coupling reaction (AL-OL coupling reaction) to supply 11-cis retinal in the carp cone retinoid cycle.

    Science.gov (United States)

    Sato, Shinya; Miyazono, Sadaharu; Tachibanaki, Shuji; Kawamura, Satoru

    2015-01-30

    Cone photoreceptors require effective pigment regeneration mechanisms to maintain their sensitivity in the light. Our previous studies in carp cones suggested the presence of an unconventional and very effective mechanism to produce 11-cis retinal, the necessary component in pigment regeneration. In this reaction (aldehyde-alcohol redox coupling reaction, AL-OL coupling reaction), formation of 11-cis retinal, i.e. oxidation of 11-cis retinol is coupled to reduction of an aldehyde at a 1:1 molar ratio without exogenous NADP(H) which is usually required in this kind of reaction. Here, we identified carp retinol dehydrogenase 13-like (RDH13L) as an enzyme catalyzing the AL-OL coupling reaction. RDH13L was partially purified from purified carp cones, identified as a candidate protein, and its AL-OL coupling activity was confirmed using recombinant RDH13L. We further examined the substrate specificity, subcellular localization, and expression level of RDH13L. Based on these results, we concluded that RDH13L contributes to a significant part, but not all, of the AL-OL coupling activity in carp cones. RDH13L contained tightly bound NADP(+) which presumably functions as a cofactor in the reaction. Mouse RDH14, a mouse homolog of carp RDH13L, also showed the AL-OL coupling activity. Interestingly, although carp cone membranes, carp RDH13L and mouse RDH14 all showed the coupling activity at 15-37 °C, they also showed a conventional NADP(+)-dependent 11-cis retinol oxidation activity above 25 °C without addition of aldehydes. This dual mechanism of 11-cis retinal synthesis attained by carp RDH13L and mouse RDH14 probably contribute to effective pigment regeneration in cones that function in the light. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Reactions of charged and neutral recoil particles following nuclear transformations. Progress report No. 11, September 1976--August 1977

    International Nuclear Information System (INIS)

    Ache, H.J.

    1977-09-01

    The status of the following programs is reported: study of the stereochemistry of halogen atom reactions produced via (n,γ) nuclear reactions with diastereomeric molecules in the condensed phase; decay-induced labelling of compounds of biochemical interest; reactions of energetic tritium species in graphite; and positron lifetime measurements in γ-irradiated organic solids

  3. 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)

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

    Directory of Open Access Journals (Sweden)

    Qingcai Xu

    2015-01-01

    Full Text Available 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 spectrometry. The results indicated that this method of dry ashing coupled with two-step ion-exchange chromatography is powerful for the separation of boron in plant sample with large amounts of organic matters completely. The ratios of boron isotope composition in those plant tissue samples ranged from -19.45‰ to +28.13‰ (total range: 47.58‰ with a mean value of 2.61±11.76‰ SD. The stem and root isotopic compositions were lower than those in flower and leaf. The molecular mechanism of boron isotope may be responsible for the observed variation of boron isotopic composition and are considered as a useful tool for the better understanding of boron cycling process in the environment and for the signature of living systems.

  5. Indirect study of {sup 11}B(p,alpha{sub 0}){sup 8}Be and {sup 10}B(p,alpha){sup 7}Be reactions at astrophysical energies by means of the Trojan Horse Method: recent results

    Energy Technology Data Exchange (ETDEWEB)

    Lamia, L.; Puglia, S.M.R.; Spitaleri, C.; Romano, S. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Del Santo, M. Gimenez; Carlin, N.; Munhoz, M. Gameiro [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Cherubini, S. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Kiss, G.G. [Laboratori Nazionali del Sud, Catania (Italy); Atomki, Debrecen (Hungary); Kroha, V. [Institute for Nuclear Physics, Prague (Czech Republic); Kubono, S. [CNS, University of Tokyo, Tokyo (Japan); La Cognata, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Li Chengbo [China Institute of Atomic Energy, Department of Physics, Beijing (China); Pizzone, R.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Wen Qungang [China Institute of Atomic Energy, Department of Physics, Beijing (China); Sergi, M.L. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Szanto de Toledo, A. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Wakabayashi, Y. [CNS, University of Tokyo, Tokyo (Japan); Advanced Science Research Center - JAEA - Ibaraki (Japan); Yamaguchi, H. [CNS, University of Tokyo, Tokyo (Japan); Zhou Shuhua [China Institute of Atomic Energy, Department of Physics, Beijing (China)

    2010-03-01

    Nuclear (p,alpha) reactions destroying the so-called 'light-elements' lithium, beryllium and boron have been largely studied in the past mainly because their role in understanding some astrophysical phenomena, i.e. mixing-phenomena occurring in young F-G stars [A.M. Boesgaard et al., Astr. Phys. J, 991, 2005, 621]. Such mechanisms transport the surface material down to the region close to the nuclear destruction zone, where typical temperatures of the order of approx10{sup 6} K are reached. The corresponding Gamow energy E{sub 0}=1.22(Z{sub x}{sup 2}Z{sub X}{sup 2}T{sub 6}{sup 2}){sup 1/3} keV [C. Rolfs and W. Rodney, 'Cauldrons in the Cosmos', The Univ. of Chicago press, 1988] is about approx10 keV if one considers the 'boron-case' and replaces in the previous formula Z{sub x}=1, Z{sub X}=5 and T{sub 6}=5. Direct measurements of the two {sup 11}B(p,alpha{sub 0}){sup 8}Be and {sup 10}B(p,alpha){sup 7}Be reactions in correspondence of this energy region are difficult to perform mainly because the combined effects of Coulomb barrier penetrability and electron screening [H.J. Assenbaum, K. Langanke and C. Rolfs, Z. Phys., 327, 1987, 461]. The indirect method of the Trojan Horse (THM) [G. Baur et al., Phys. Lett. B, 178, 1986, 135; G. Calvi et al., Nucl. Phys. A, 621, 1997, 139; C. Spitaleri et al., Phys. Rev. C, 493, 1999, 206] allows one to extract the two-body reaction cross section of interest for astrophysics without the extrapolation-procedures. Due to the THM formalism, the extracted indirect data have to be normalized to the available direct ones at higher energies thus implying that the method is a complementary tool in solving some still open questions for both nuclear and astrophysical issues [S. Cherubini et al., Astr. Phys. J, 457, 1996, 855; C. Spitaleri et al., Phys. Rev. C, 63, 2001, 005801; C. Spitaleri et al., Phys. Rev. C, 63, 2004, 055806; A. Tumino et al., Phys. Rev. Lett., 98, 2007, 252502; M. La Cognata et al., Phys

  6. Kinetics of chemical vapor deposition of boron on molybdenum

    International Nuclear Information System (INIS)

    Tanaka, H.; Nakanishi, 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 experiments were conducted at atmospheric pressure. The weight change of the sample was noted by means of a thermobalance. Molybdenum was used as the substrate. It has been found that the outer layer of the deposited film is Mo/sub 2/B/sub 5/ and the inner layer is MoB, and in the stational state of the reaction, the diffusion in the solid state is considered not to be rate controlling. When mass transport limitation was absent, the reaction orders with respect to boron trichloride and hydrogen were one third and one half, respectively. By comparing these orders with those obtained from Langmuir-Hinshelwood type equations, the rate controlling mechanism is identified to be the desorption of hydrogen chloride from the substrate

  7. Thermoelectric properties of boron and boron phosphide CVD wafers

    Energy Technology Data Exchange (ETDEWEB)

    Kumashiro, Y.; Yokoyama, T.; Sato, A.; Ando, Y. [Yokohama National Univ. (Japan)

    1997-10-01

    Electrical and thermal conductivities and thermoelectric power of p-type boron and n-type boron phosphide wafers with amorphous and polycrystalline structures were measured up to high temperatures. The electrical conductivity of amorphous boron wafers is compatible to that of polycrystals at high temperatures and obeys Mott`s T{sup -{1/4}} rule. The thermoelectric power of polycrystalline boron decreases with increasing temperature, while that of amorphous boron is almost constant in a wide temperature range. The weak temperature dependence of the thermal conductivity of BP polycrystalline wafers reflects phonon scattering by grain boundaries. Thermal conductivity of an amorphous boron wafer is almost constant in a wide temperature range, showing a characteristic of a glass. The figure of merit of polycrystalline BP wafers is 10{sup -7}/K at high temperatures while that of amorphous boron is 10{sup -5}/K.

  8. Microstructural characterization aluminium alloys from the addition of boron

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  9. Ion implantation of boron in germanium

    International Nuclear Information System (INIS)

    Jones, K.S.

    1985-05-01

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

  10. New Carbonate Standard Reference Materials for Boron Isotope Geochemistry

    Science.gov (United States)

    Stewart, J.; Christopher, S. J.; Day, R. D.

    2015-12-01

    The isotopic composition of boron11B) in marine carbonates is well established as a proxy for past ocean pH. Yet, before palaeoceanographic interpretation can be made, rigorous assessment of analytical uncertainty of δ11B data is required; particularly in light of recent interlaboratory comparison studies that reported significant measurement disagreement between laboratories [1]. Well characterised boron standard reference materials (SRMs) in a carbonate matrix are needed to assess the accuracy and precision of carbonate δ11B measurements throughout the entire procedural chemistry; from sample cleaning, to ionic separation of boron from the carbonate matrix, and final δ11B measurement by multi-collector inductively coupled plasma mass spectrometry. To date only two carbonate reference materials exist that have been value-assigned by the boron isotope measurement community [2]; JCp-1 (porites coral) and JCt-1 (Giant Clam) [3]. The National Institute of Standards and Technology (NIST) will supplement these existing standards with new solution based inorganic carbonate boron SRMs that replicate typical foraminiferal and coral B/Ca ratios and δ11B values. These new SRMs will not only ensure quality control of full procedural chemistry between laboratories, but have the added benefits of being both in abundant supply and free from any restrictions associated with shipment of biogenic samples derived from protected species. Here we present in-house δ11B measurements of these new boron carbonate SRM solutions. These preliminary data will feed into an interlaboratory comparison study to establish certified values for these new NIST SRMs. 1. Foster, G.L., et al., Chemical Geology, 2013. 358(0): p. 1-14. 2. Gutjahr, M., et al., Boron Isotope Intercomparison Project (BIIP): Development of a new carbonate standard for stable isotopic analyses. Geophysical Research Abstracts, EGU General Assembly 2014, 2014. 16(EGU2014-5028-1). 3. Inoue, M., et al., Geostandards and

  11. Boron-carbide-aluminum and boron-carbide-reactive metal cermets. [B/sub 4/C-Al

    Science.gov (United States)

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

    1985-05-06

    Hard, tough, lighweight 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 consolidated step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modules of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi..sqrt..in. These composites and methods can be used to form a variety of structural elements.

  12. Relationship between reaction time, fine motor control, and visual-spatial perception on vigilance and visual-motor tasks in 22q11.2 Deletion Syndrome.

    LENUS (Irish Health Repository)

    Howley, Sarah A

    2012-10-15

    22q11.2 Deletion Syndrome (22q11DS) is a common microdeletion disorder associated with mild to moderate intellectual disability and specific neurocognitive deficits, particularly in visual-motor and attentional abilities. Currently there is evidence that the visual-motor profile of 22q11DS is not entirely mediated by intellectual disability and that these individuals have specific deficits in visual-motor integration. However, the extent to which attentional deficits, such as vigilance, influence impairments on visual motor tasks in 22q11DS is unclear. This study examines visual-motor abilities and reaction time using a range of standardised tests in 35 children with 22q11DS, 26 age-matched typically developing (TD) sibling controls and 17 low-IQ community controls. Statistically significant deficits were observed in the 22q11DS group compared to both low-IQ and TD control groups on a timed fine motor control and accuracy task. The 22q11DS group performed significantly better than the low-IQ control group on an untimed drawing task and were equivalent to the TD control group on point accuracy and simple reaction time tests. Results suggest that visual motor deficits in 22q11DS are primarily attributable to deficits in psychomotor speed which becomes apparent when tasks are timed versus untimed. Moreover, the integration of visual and motor information may be intact and, indeed, represent a relative strength in 22q11DS when there are no time constraints imposed. While this may have significant implications for cognitive remediation strategies for children with 22q11DS, the relationship between reaction time, visual reasoning, cognitive complexity, fine motor speed and accuracy, and graphomotor ability on visual-motor tasks is still unclear.

  13. Base free aryl coupling of diazonium compounds and boronic esters: self-activation allowing an overall highly practical process.

    Science.gov (United States)

    Bonin, Hélène; Delbrayelle, Dominique; Demonchaux, Patrice; Gras, Emmanuel

    2010-04-21

    Boronic esters have long been considered as poor partners in cross-coupling reactions with arene diazoniums. Here is reported an unprecedented application of self-activated boronic esters in a base-free cross-coupling reaction with diazonium salts under mild and user friendly conditions.

  14. Robotized synthesis of [3-11C]-L-alanine using reaction of asymmetric alkylation of 11CH3I nickel complex of glycine Schiff base with S-2-N-(N'-benzylpropyl)aminobenzophenone

    International Nuclear Information System (INIS)

    Mosevich, I.K.; Kuznetsova, O.F.; Vasil'ev, D.A.; Anichkov, A.A.; Korsakov, M.V.

    1999-01-01

    Synthesis of [3- 11 C]-L-alanine based on 11 CH 3 I nickel complex (1) alkylation using different solvents (tetrahydrofuran, dimethylformamide, acetonitrile, acetone) and catalysts (potassium butylate, sodium hydride) was investigated. It was shown that synthesis of amino acids labelled with 11 C based on complex (1) use permits to obtain preparations with high degree of enantiomeric enrichment. The best results (enantiomeric excess of L-alanine up to 99 %) were obtained in reaction with acetonitrile as a solvent and potassium tret-butylate as a catalyst

  15. Reactions of 11C recoil atoms in the systems H2O-NH3, H2O-CH4 and NH3-CH4

    International Nuclear Information System (INIS)

    Nebeling, B.

    1988-11-01

    In this study the chemical reactions of recoil carbon 11 in the binary gas mixtures H 2 O-NH 3 , H 2 O-CH 4 and NH 3 -CH 4 in different mixing ratios as well as in solid H 2 O and in a solid H 2 O-NH 3 mixture were analyzed in dependence of the dose. The analyses were to serve e.g. the simulation of chemical processes caused by solar wind, solar radiation and cosmic radiation in the coma and core of comets. They were to give further information about the role of the most important biogeneous element carbon, i.e. carbon, in the chemical evolution of the solar system. Besides the actual high energy processes resulting in the so-called primary products, also the radiation-chemical changes of the primary products were also observed in a wide range of dosing. The generation of the energetic 11 C atoms took place according to the target composition by the nuclear reactions 14 N(p,α) 11 C, 12 C( 3 He,α) 11 C or the 16 O(p,αpn) 11 C reaction. The identification of the products marked with 11 C was carried out by means of radio gas chromatography or radio liquid chromatography (HPLC). (orig./RB) [de

  16. Proposed physiologic functions of boron in plants pertinent to animal and human metabolism.

    Science.gov (United States)

    Blevins, D G; Lukaszewski, K M

    1994-01-01

    Boron has been recognized since 1923 as an essential micronutrient element for higher plants. Over the years, many roles for boron in plants have been proposed, including functions in sugar transport, cell wall synthesis and lignification, cell wall structure, carbohydrate metabolism, RNA metabolism, respiration, indole acetic acid metabolism, phenol metabolism and membrane transport. However, the mechanism of boron involvement in each case remains unclear. Recent work has focused on two major plant-cell components: cell walls and membranes. In both, boron could play a structural role by bridging hydroxyl groups. In membranes, it could also be involved in ion transport and redox reactions by stimulating enzymes like nicotinamide adenine dinucleotide and reduced (NADH) oxidase. There is a very narrow window between the levels of boron required by and toxic to plants. The mechanisms of boron toxicity are also unknown. In nitrogen-fixing leguminous plants, foliarly applied boron causes up to a 1000% increase in the concentration of allantoic acid in leaves. In vitro studies show that boron inhibits the manganese-dependent allantoate amidohydrolase, and foliar application of manganese prior to application of boron eliminates allantoic acid accumulation in leaves. Interaction between borate and divalent cations like manganese may alter metabolic pathways, which could explain why higher concentrations of boron can be toxic to plants. PMID:7889877

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

    International Nuclear Information System (INIS)

    Kitaoka, Yoshinori

    1993-09-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-28

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

  19. Exact finite range DWBA results for the /sup 12/C(p,d)/sup 11/C reaction at 700 MeV. [Differential cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Rost, E; Shepard, J R [Colorado Univ., Boulder (USA). Nuclear Physics Lab.

    1975-12-08

    The differential cross sections for the /sup 12/C(p,d)/sup 11/C(g.s.) reaction at 700 MeV have been calculated in a full finite range DWBA approach. The absolute cross sections agree with the data and are dominated by contributions arising from the deuteron D-state.

  20. Implementation of 5E Inquiry Incorporated with Analogy Learning Approach to Enhance Conceptual Understanding of Chemical Reaction Rate for Grade 11 Students

    Science.gov (United States)

    Supasorn, Saksri; Promarak, Vinich

    2015-01-01

    The main purpose of this study was to enhance student understanding of the scientific concepts of chemical reaction rate. Forty-four grade 11 students were the target group. The treatment tools were seven learning plans of 5E inquiry incorporated with an analogy learning approach during 15 hours of class time. In each learning plan, the students…

  1. Five-nucleon simultaneous and sequential transfer in the 12C(11B,6Li)17O and 12C(d,7Li)7Be reactions

    International Nuclear Information System (INIS)

    Jarczyk, L.; Kamys, B.; Kistryn, M.; Magiera, A.; Rudy, Z.; Strzal/kowski, A.; Barna, R.; DAmico, V.; De Pasquale, D.; Italiano, A.; Licandro, M.

    1996-01-01

    Measurements of the angular distributions of the 12 C( 11 B, 6 Li) 17 O reaction were performed at three energies of a 11 B beam: 28, 35, and 40 MeV. The results were analyzed in the frame of the exact finite range distorted wave Born approximation of the first and the second order assuming the simultaneous and sequential transfer of the neutron and the α particle. Such an analysis was also performed for previously measured angular distributions of the 12 C(d, 7 Li) 7 Be reaction at E lab = 78 MeV. In both reactions under investigation dominance was found of the simultaneous transfer of the α particle and the nucleon correlated to the 5 He ( 5 Li) cluster in the ground or the first excited state. copyright 1996 The American Physical Society

  2. 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

  3. Determination of microdistribution of boron in metals

    Energy Technology Data Exchange (ETDEWEB)

    Illic, R; Najzer, M; Rant, J [J. Stefan Institute, Ljubljana (Yugoslavia)

    1976-07-01

    A neutron induced autoradiographic technique was used for the determination of the boron microdistribution in metals. The specimens, which were in close contact with a LR 115 SSTD, were irradiated in the exposure room of the TRIGA Mark II reactor in Ljubljana. The spatial resolution of the autoradiographic image recorded by the LR 115 detector was found to be influenced mainly by the size of the reaction product tracks. The track diameter of a normally etched detector was about 7 {mu}m. An appreciable reduction of track size was achieved by pre-etching the detector foil before neutron irradiation. By this procedure it was possible to obtain a track diameter as small as 1 {mu}m and correspondingly to improve the spatial resolution of the autoradiographs of type EC 80 steel and Al Mg 3 alloy which contain 30 and 2 ppm of boron respectively. (author)

  4. 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)

  5. Interaction of model aryl- and alkyl-boronic acids and 1,2-diols in aqueous solution.

    Science.gov (United States)

    Marinaro, William A; Prankerd, Richard; Kinnari, Kaisa; Stella, Valentino J

    2015-04-01

    The goal of this work was to quantitate ester formation between alkyl and aryl boronic acids and vicinal-diols or 1,2-diols in aqueous solution. As used here, 1,2-diols includes polyols with one or more 1,2-diol pairs. Multiple techniques were used including apparent pKa shifts of the boronic acids using UV spectrophotometry (for aryl acids) and titration (for aryl and alkyl acids). Isothermal microcalorimetry was also used, with all reactions being enthalpically favored. For all the acids and 1,2-diols and the conditions studied, evidence only supported 1:1 ester formation. All the esters formed were found to be significantly more acidic, as Lewis acids, by 3-3.5 pKa units than the corresponding nonesterified boronic acid. The equilibrium constants for ester formation increased with increasing number of 1,2-diol pairs but stereochemistry may also play a role as sorbitol with five possible 1,2-diol pairs and five isomers (taking into account the stereochemistry of the alcohol groups) was twice as efficient at ester formation compared with mannitol, also with five possible 1,2-diol pairs but only three isomers. Alkyl boronic acids formed esters to a greater extent than aryl acids. Although some quantitative differences were seen between the various techniques used, rank ordering of the structure/reactivity was consistent. Formulation implications of ester formation between boronic acids and 1,2-diols are discussed. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

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

    International Nuclear Information System (INIS)

    Yilmaz, A. Erdem; Boncukcuoglu, Recep; Kocakerim, M. Muhtar

    2007-01-01

    In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0mA/cm 2 , initial boron concentration 100mg/L and solution temperature 293K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following;[ECB]=7.6x10 6 x[OH] 0.11 x[CD] 0.62 x[IBC] -0.57 x[DSE] -0.04 x[T] -2.98 x[t] Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-06-01

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

  8. Fine-tuning the nucleophilic reactivities of boron ate complexes derived from aryl and heteroaryl boronic esters.

    Science.gov (United States)

    Berionni, Guillaume; Leonov, Artem I; Mayer, Peter; Ofial, Armin R; Mayr, Herbert

    2015-02-23

    Boron ate complexes derived from thienyl and furyl boronic esters and aryllithium compounds have been isolated and characterized by X-ray crystallography. Products and mechanisms of their reactions with carbenium and iminium ions have been analyzed. Kinetics of these reactions were monitored by UV/Vis spectroscopy, and the influence of the aryl substituents, the diol ligands (pinacol, ethylene glycol, neopentyl glycol, catechol), and the counterions on the nucleophilic reactivity of the boron ate complexes were examined. A Hammett correlation confirmed the polar nature of their reactions with benzhydrylium ions, and the correlation lg k(20 °C)=sN (E+N) was employed to determine the nucleophilicities of the boron ate complexes and to compare them with those of other borates and boronates. The neopentyl and ethylene glycol derivatives were found to be 10(4) times more reactive than the pinacol and catechol derivatives. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Boron exposure assessment using drinking water and urine in the North of Chile

    Energy Technology Data Exchange (ETDEWEB)

    Cortes, S., E-mail: scortes@med.puc.cl [Departamento de Salud Publica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Reynaga-Delgado, E. [Centro de Investigaciones Biologicas del Noroeste, La Paz B.C.S. (Mexico); Sancha, A.M. [Facultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Santiago (Chile); Ferreccio, C. [Departamento de Salud Publica, Pontificia Universidad Catolica de Chile, Santiago (Chile)

    2011-12-01

    Boron is an essential trace element for plants and humans however it is still an open question what levels of boron are actually safe for humans. This study, conducted between 2006 and 2010, measured exposure levels of boron in drinking water and urine of volunteers in Arica, an area in the North of Chile with high levels of naturally occurring boron. Samples were taken of tap and bottled water (173 and 22, respectively), as well as urine from 22 volunteers, and subsequently analyzed by inductively coupled plasma spectroscopy (ICP-OES). Boron varied in public tap water from 0.22 to 11.3 mg L{sup -1}, with a median value of 2.9 mg L{sup -1}, while concentrations of boron in bottled water varied from 0.01 to 12.2 mg L{sup -1}. Neither tap nor bottled water samples had concentrations of boron within WHO recommended limits. The concentration of boron in urine varied between 0.45 and 17.4 mg L{sup -1}, with a median of 4.28 mg L{sup -1} and was found to be correlated with tap water sampled from the homes of the volunteers (r = 0.64). Authors highly recommend that in northern Chile - where levels of boron are naturally high - that the tap and bottled water supplies be monitored in order to protect public health and that regulatory standards also be established for boron in drinking water in order to limit exposure.

  10. Study and optimization of the carbothermic reduction process for obtaining boron carbide

    International Nuclear Information System (INIS)

    Castro, A.R.M. de.

    1989-01-01

    Boron carbide - B sub(4)C - is a ceramic material of technological importance due to its hardness and high chemical and thermal stabilities. Moreover, its high neutron capture cross section makes it suitable for application as neutron absorber in nuclear technology. The process for obtaining carbothermally derived boron carbide has been studied in two steps: firstly, the parameters of the boric acid → boron oxide dehydration reaction have been defined; secondly, the optimization of the carbothermal reduction reaction using boron oxide has been undertaken looking for boron carbide having low level of free carbon. The starting materials as well as the main products have been studied by chemical and spectrographic analyses, X-ray diffractometry, granulometric classification and scanning electron microscopy. The optimization of the carbothermic reduction process allowed for the development and set up of a fabrication procedure yielding high quality B sub(4) C powders, starting from low cost and easily available (in the Brazilian market) raw materials. (author)

  11. Oxytetracycline as a new analytical reagent for the spectrophotometric determination of boron

    Energy Technology Data Exchange (ETDEWEB)

    Narayana, G L

    1984-05-01

    Oxytetracycline hydrochloride, Terramycin, is introduced as a new reagent for the spectrophotometric determination of trace quantities of boron in concentrated sulphuric acid medium. The reagent has an absorption maximum at 430 nm, and that of the boron complex at 520 nm. The colored system conformed to Beer's law between 2 and 10 ..mu..g of boron at 520 nm. The molar absorptivity calculated on the basis of boron is 10,800 1 mol/sup -1/ cm/sup -1/. The composition of the complex has been shown to be 1:1 both by the slope ratio and molar ratio methods. 16 references.

  12. Oxytetracycline as a new analytical reagent for the spectrophotometric determination of boron

    International Nuclear Information System (INIS)

    Narayana, G.L.

    1984-01-01

    Oxytetracycline hydrochloride, Terramycin, is introduced as a new reagent for the spectrophotometric determination of trace quantities of boron in concentrated sulphuric acid medium. The reagent has an absorption maximum at 430 nm, and that of the boron complex at 520 nm. The coloured system conformed to Beer's law between 2 and 10 μg of boron at 520 nm. The molar absorptivity calculated on the basis of boron is 10,800 1 mol -1 cm -1 . The composition of the complex has been shown to be 1:1 both by the slope ratio and molar ratio methods. (author)

  13. The Influence of Parameters Affecting Boron Removal by Electrocoagulation Process

    KAUST Repository

    Zeboudji, B.

    2013-04-01

    Boron removal in seawater desalination presents a particular challenge. In seawater reverse osmosis (SWRO) systems boron removal at low concentration (<0.5 mg/L) is usually achieved by a second pass using brackish water RO membranes. However, this process requires chemical addition and important additional investment, operation and maintenance, and energy costs. Electrocoagulation (EC) process can be used to achieve such low boron concentration. In this work, the removal of boron from aqueous solution was carried out by EC process using aluminum and iron electrodes. Several operating parameters on the removal efficiency such as initial pH, current density, initial boron ion concentration, feed concentration, gap between electrodes, and electrode material, were investigated. In the case of bipolar electrocoagulation (BEC), an optimum removal efficiency of 96% corresponding to a final boron concentration of 0.4 mg/L was achieved at a current density of 6 mA/cm2 and pH = 8 using aluminum electrodes. The concentration of NaCl was 2,500 mg/L and the gap between the electrodes of 0.5 cm. Furthermore, a comparison between monopolar electrocoagulation (MEC) and BEC using both aluminum and iron electrodes was carried out. Results showed that the BEC process has reduced the current density applied to obtain high level of boron removal in a short reaction time compared to MEC process. The high performance of the EC showed that the process could be used to reduce boron concentration to acceptable levels at low-cost and more environmentally friendly. © 2013 Copyright Taylor and Francis Group, LLC.

  14. Investigations on boron isotopic geochemistry of salt lakes in Qaidam basin, Qinghai

    Digital Repository Service at National Institute of Oceanography (India)

    Xiao, Y; Shirodkar, P.V.; Liu, W.G.; Wang, Y; Jin, L.

    of brine and are related to boron origin, the corrosion of salt and to certain chemical constituents. The distribution of boron isotopes in Quidam Basin showed a regional feature: salt lake brines in the west and northwest basin have the highest d11B values...

  15. Boron chemistry in relation to its variations in eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shirodkar, P.V.; Singbal, S.Y.S.

    in the offshore waters. Percent addition and removal of boron computEd. by taking into consideration the world average B/Cl of 0.232 indicated an addition up to 16% and removal up to 11.65% resulting in a net addition of boron to the coastal waters. At few...

  16. Current status of boron neutron capture therapy of high grade gliomas and recurrent head and neck cancer

    Directory of Open Access Journals (Sweden)

    Barth Rolf F

    2012-08-01

    Full Text Available Abstract Boron neutron capture therapy (BNCT is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, is irradiated with low energy thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium-7 nuclei. Clinical interest in BNCT has focused primarily on the treatment of high grade gliomas, recurrent cancers of the head and neck region and either primary or metastatic melanoma. Neutron sources for BNCT currently have been limited to specially modified nuclear reactors, which are or until the recent Japanese natural disaster, were available in Japan, United States, Finland and several other European countries, Argentina and Taiwan. Accelerators producing epithermal neutron beams also could be used for BNCT and these are being developed in several countries. It is anticipated that the first Japanese accelerator will be available for therapeutic use in 2013. The major hurdle for the design and synthesis of boron delivery agents has been the requirement for selective tumor targeting to achieve boron concentrations in the range of 20 μg/g. This would be sufficient to deliver therapeutic doses of radiation with minimal normal tissue toxicity. Two boron drugs have been used clinically, a dihydroxyboryl derivative of phenylalanine, referred to as boronophenylalanine or “BPA”, and sodium borocaptate or “BSH” (Na2B12H11SH. In this report we will provide an overview of other boron delivery agents that currently are under evaluation, neutron sources in use or under development for BNCT, clinical dosimetry, treatment planning, and finally a summary of previous and on-going clinical studies for high grade gliomas and recurrent tumors of the head and neck region. Promising results have been obtained with both groups of patients but these outcomes must be more rigorously evaluated in larger

  17. Nuclear magnetic resonance study of reaction of p-(1,1', 3,3'-tetramethylbutyl)phenol with phosphoric pentoxide

    International Nuclear Information System (INIS)

    Didi, Mohamed Amine; Elias Abdelhamid

    1998-12-01

    Some aspects dealing with the mechanisms and the kinetics of the reaction between phosphorus pentoxide and p-(1,1',3,3'-tetramethylbutyl)phenol were investigated, by means of the 31P nmr technique . The kinetic model considered showed that only the time and, to a lesser extent, the temperature of the reaction seem to the yield. The reactant mode ratio does not exhibit any effect upon the MOPPA DOPPA ratio. A series of adequate experiments based on the 2 factorial 3 plane method allowed to confirm these results. The tripyroesters were identified as being the longest intermediates detected by nmr. In the reaction mixture no traces of phosphoric triester (t- TOPPA) were detected

  18. Radiation-enhanced self- and boron diffusion in germanium

    DEFF Research Database (Denmark)

    Schneider, S.; Bracht, H.; Klug, J.N.

    2013-01-01

    We report experiments on proton radiation-enhanced self- and boron (B) diffusion in germanium (Ge) for temperatures between 515 ∘ C and 720 ∘ C. Modeling of the experimental diffusion profiles measured by means of secondary ion mass spectrometry is achieved on the basis of the Frenkel pair reaction...

  19. Application of the boron autoradiography in structural steels

    International Nuclear Information System (INIS)

    Azevedo, A.L.T. de

    1985-01-01

    An example of the use of the autoradiographic method for obtaining boron distribution images is described. The technique is based on an emitting nuclear reaction (neutron irradiation), which leaves a latent track in a cellulose film. This detector material is revealed by chemical etching and observed by optical and electron transmission microscopy. (Author) [pt

  20. Structure and photoluminescence of boron and nitrogen co-doped carbon nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Gao, B. [College of Computer Science, Chongqing University, Chongqing 400044 (China); Chongqing Municipal Education Examinations Authority, Chongqing 401147 (China); Zhong, X.X., E-mail: xxzhong@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Shao, R.W.; Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

    2016-07-15

    Graphical abstract: Boron- and nitrogen- doped carbon nanorods. - Highlights: • The co-doping of nitrogen and boron in carbon nanorods. • The doping mechanism of nitrogen and boron in carbon nanorods by plasma. • Photoluminescence properties of nitrogen- and boron-doped carbon nanorods. - Abstract: Boron and nitrogen doped carbon nanorods (BNCNRs) were synthesized by plasma-enhanced hot filament chemical vapor deposition, where methane, nitrogen and hydrogen were used as the reaction gases and boron carbide was the boron source. The results of scanning electron microscopy, micro-Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy indicate that boron and nitrogen can be used as co-dopants in amorphous carbon nanorods. Combined with the characterization results, the doping mechanism was studied. The mechanism is used to explain the formation of different carbon materials by different methods. The photoluminescence (PL) properties of BNCNRs were studied. The PL results show that the BNCNRs generate strong green PL bands and weak blue PL bands, and the PL intensity lowered due to the doping of boron. The outcomes advance our knowledge on the synthesis and optical properties of carbon-based nanomaterials and contribute to the development of optoelectronic nanodevices based on nano-carbon mateirals.

  1. 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

  2. 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)

  3. A review of reaction rates and thermodynamic and transport properties for the 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

    Science.gov (United States)

    Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.

    1989-01-01

    Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.

  4. Stereoselective reactions. XXXII. Enantioselective deprotonation of 4-tert-butylcyclohexanone by fluorine-containing chiral lithium amides derived from 1-phenylethylamine and 1-(1-naphthyl)ethylamine.

    Science.gov (United States)

    Aoki, K; Koga, K

    2000-04-01

    Enantioselective deprotonation of 4-tert-butylcyclohexanone was examined using 1-phenylethylamine- and 1-(1-naphthyl)ethylamine-derived chiral lithium amides having an alkyl or a fluoroalkyl substituent at the amide nitrogen. The lithium amides having a 2,2,2-trifluoroethyl group on the amide nitrogen are easily accessible in both enantiomeric forms, and were found to induce good enantioselectivity in the present reaction.

  5. Dual-level direct dynamics studies for the hydrogen abstraction reaction of 1,1-difluoroethane with O( 3P)

    Science.gov (United States)

    Liu, Jing-yao; Li, Ze-sheng; Dai, Zhen-wen; Zhang, Gang; Sun, Chia-chung

    2004-01-01

    We present dual-level direct dynamics calculations for the CH 3CHF 2 + O( 3P) hydrogen abstraction reaction in a wide temperature range, based on canonical variational transition-state theory including small curvature tunneling corrections. For this reaction, three distinct transition states, one for α-abstraction and two for β-abstraction, have been located. The potential energy surface information is obtained at the MP2(full)/6-311G(d,p) level of theory, and higher-level single-point calculations for the stationary points are preformed at several levels, namely QCISD(T)/6-311+G(3df,3pd), G2, and G3 using the MP2 geometries, as well as at the G3//MP4SDQ/6-311G(d,p) level. The energy profiles are further refined with the interpolated single-point energies method at the G3//MP2(full)/6-311G(d,p) level. The total rate constants match the experimental data reasonable well in the measured temperature range 1110-1340 K. It is shown that at low temperature α-abstraction may be the major reaction channel, while β-abstraction will have more contribution to the whole reaction rate as the temperature increases.

  6. Investigation of Hard Boron Rich Solids: Osmium Diboride and β-Rhombohedral Boron

    Science.gov (United States)

    Hebbache, M.; Živković, D.

    Recently, we succeeded in synthesizing three osmium borides, i.e., OsB1.1, Os2B3 and OsB2. Up to date, almost nothing is known about the physical properties of these materials. Microhardness measurements show that OsB2 is extremely hard. Ab initio calculations show that it is due to formation of covalent bonds between boron atoms. OsB2 is also a low compressibility material. It can be used for hard coatings. The β-rhombohedral polymorph of boron is the second hardest elemental crystal (H ≈ 33 GPa). It is also very light and a p-type semiconductor. In early 1970s, it has been shown that the doping of boron with 3d transition elements enhances its hardness by about 25%. We predict that, in general, heavily doped samples MBx, with x ≤ 31 or equivalently a dopant concentration larger than 3.2 at.%, should be ultrahard, i.e., H > 43 GPa. The relevant dopants M are Al, Cu, Sc, Mn, Mg and Li. In addition to these properties, boron-rich materials have a very low volatility, a high chemical inertness and high melting point. They are suitable for applications under extreme conditions and thermoelectric equipment.

  7. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-03-01

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

  9. Radioisotope tracer study of co-reactions of methanol with ethanol using 11C-labelled methanol over alumina and H-ZSM-5

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Kumar, N.; Salmi, T.; Murzin, D.Yu

    2005-01-01

    Complete text of publication follows. The transformation of methanol has been investigated over alumina and H-ZSM-5 in our previous experiments by 11 C-radioisotope tracing. The main product in methanol conversion over alumina was dimethyl ether due to Lewis acid sites while over H-ZSM-5 mostly hydrocarbons were formed due to both Lewis and Brrnsted acid sites. With increasing temperature first the ethanol was dehydrated to diethyl ether followed by ethene formation over alumina and H-ZSM-5. In this work, 11 C-labelled methanol as radioisotope tracer was added to non-radioactive methanol for investigation of co-reaction with non-radioactive ethanol over alumina and H- ZSM-5. The 11 C-methanol tracer was used to distinguish the methanol derivates and co-reaction derivates of methanol with ethanol against non-radioactive ethanol derivates. The yield of methyl ethyl ether as mixed ether and the influence of ethanol for the yields of C 1 -C 5 hydrocarbons were studied as a function of reaction temperature and contact time. The 11 C-methanol was formed by a radiochemical process from 11 CO 2 produced at cyclotron. The mixture of methanol and ethanol was added to 11 C-methanol and injected to the catalyst. The catalysis was carried out in a glass tube fixed-bed reactor after its pretreatment. The derivates were analyzed by radio-gas chromatography (gas chromatograph with thermal conductivity detector coupled on-line with a radioactivity detector). The comparative analysis of yields of radioactive and non-radioactive products as a function of reaction temperature gives information about the reaction pathways. Over alumina the yields of dimethyl ether and methyl ethyl ether (co-product) as radioactive and diethyl ether with ethene as non-radioactive main products were monitored as a function of reaction temperature and reaction time in the range of 513-593 K. Alongside ethanol derivates the ethene turns into main product in contrast with methyl ethyl ether and diethyl

  10. Practical experiences with the synthesis of [11C]CH3I through gas phase iodination reaction using a TRACERlabFXC synthesis module

    International Nuclear Information System (INIS)

    Kniess, Torsten; Rode, Katrin; Wuest, Frank

    2008-01-01

    The results of [ 11 C]CH 3 I synthesis through hydrogen gas reduction of [ 11 C]CO 2 on different nickel catalysts (HARSHAW-nickel, SHIMALITE-nickel, nickel on silica/alumina, nickel nanosize 99.99%) followed by gas phase iodination using a TRACERlab FX C synthesis unit are reported. Further reaction parameters such as furnace temperatures, flow rate of hydrogen gas and reduction time were optimized. It was found that reduction of [ 11 C]CO 2 proceeded in 28-83% yield depending on the nickel catalyst and temperature. The gas phase iodination (methane conversion) gave 31-62% of [ 11 C]CH 3 I depending on temperature and amount of iodine in the iodine furnace. [ 11 C]CH 3 I was used for heteroatom methylation reactions exemplified by a piperazine and a phenol (1 and 3). The specific activity of the 11 C-labelled products 2 and 4 was determined after HPLC purification and solid-phase extraction. Compounds 2 and 4 were obtained in 8-14% radiochemical yield (decay-corrected, based upon trapped [ 11 C]CH 4 ) within 30 min. The specific activity was determined to be in the range of 20-30 GBq/μmol at the end-of-synthesis. Nickel catalyst nanosize was found to be superior compared with other Ni catalysts tested. The relatively low specific activity may be mainly due to carbon contaminations originating from the long copper tubing (500 m) between the cyclotron and the radiochemistry facility

  11. Study of the break reaction of Be11 on Ti48 target; the towing mode: a spectroscopic tool for the study of nuclei

    International Nuclear Information System (INIS)

    Lima, V.

    2004-10-01

    In a towing mode reaction the projectile picks up a nucleon from the target and then breaks up by emitting one nucleon. The velocity of the emitted nucleon is boosted by the projectile velocity, leading to the emission of the nucleon in a narrow cone around the direction of the scattered projectile. This work is dedicated to the towing mode in halo nuclei such as Be 11 . The experiment was performed at Ganil facility by bombarding a Ti 48 target with a 41 MeV per nucleon Be 11 beam, the reaction studied is: Ti 48 (Be 11 , Be 10 + n + γ). The first chapter reviews the various nuclear processes that take place when 2 nuclei collide with a particular attention for the towing mode. The second chapter is dedicated to solving the time dependant Schroedinger equation (TDSE) in order to assess the impact of various parameters such as incident energy, target charge or the linking energy of the nucleon, on the towing mode reaction. The third chapter deals with the experimental equipment and set-up including detectors and the data acquisition system. Computerized simulations have been performed in order to assess the efficiency of the detecting system, they are presented in the fourth chapter. A comparison between experimental data and the results from TDSE solving, concerning the energy spectra of the emitted particles, has enabled the author to deduce the spectroscopic factors for the different contributions of the fundamental state of Be 11 , they are presented in the last chapter. The cross-sections of the towing mode are of the magnitude of several tens of milli-barns in the case of weakly bound nuclei like Be 11 which make it an efficient tool to study intern structure of nuclei. (A.C.)

  12. 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.

  13. Boron supplementation in broiler diets

    Directory of Open Access Journals (Sweden)

    EJ Fassani

    2004-12-01

    Full Text Available Boron supplementation in broiler feed is not a routine practice. However, some reports suggest a positive effect of boron on performance. This study assessed the effects of boron supplementation on broiler performance. Diets were based on maize and soybean meal, using boric acid P.A. as boron source. Six supplementation levels (0, 30, 60, 90, 120 and 150 ppm were evaluated using 1,440 one-day old males housed at a density of 30 chickens in each of 48 experimental plots of 3m². A completely randomized block design was used with 8 replicates. Feed intake, weight gain and feed conversion were assessed in the periods from 1 to 7 days, 1 to 21 days and 1 to 42 days of age, and viability was evaluated for the total 42-day rearing period. No performance variable was affected by boron supplementation (p>0.05 in the period from 1 to 7 days. The regression analysis indicated an ideal level of 37.4 ppm of boron for weight gain from 1 to 21 days (p0.05, although feed intake was reduced linearly with increased boron levels (p0.05. Ash and calcium percentages in the tibias of broilers and viability in the total rearing period were not affected by boron supplementation (p>0.05.

  14. Isotopic evidence of boron in precipitation originating from coal burning in Asian continent

    International Nuclear Information System (INIS)

    Sakata, Masahiro; Natsumi, Masahiro; Tani, Yukinori

    2010-01-01

    The boron concentration and isotopic composition (δ 11 B) of precipitation collected from December 2002 to March 2006 at three sites on the Japan Sea coast were measured. Those sites have been considerably affected by the long-range transport of air pollutants from the Asian continent during winter and spring when the airflows from the Asian continent are predominant. The boron concentration in the precipitation increased primarily during winter whereas the δ 11 B decreased during winter or spring. It is assumed that this decrease in δ 11 B is not associated with a Rayleigh distillation process, because the previous δD values of the precipitation collected at a site on the Japan Sea coast did not decrease in the same manner. A weak correlation (r 2 =0.13-0.24, P 11 B and the nonsea-salt sulfate (nss-SO 4 2- )/B ratio at each site, suggesting that boron in the precipitation originate primarily from two sources. The first source, which is characterized by high δ 11 B and nss-SO 4 2- /B=0, is seawater. At the northern site, the enrichment factor for boron in the precipitation relative to seawater approached unity during winter. This implies that much of the boron in the precipitation is derived from unfractionated sea salts rather than gaseous boron evaporated from seawater. The second source is characterized by low δ 11 B and high nss-SO 4 2- /B ratio. Most of the nss-SO 4 2- in the precipitation originates from anthropogenic combustion activities in the Asian continent based on the previous model calculations. Coal accounts for a major portion of the total primary energy supply in China. Moreover, coal enriches boron and represents generally negative δ 11 B values. Hence, we propose that the emission of boron from coal burning is the most likely second source. Thus, boron isotopes may be useful as tracers of coal-burning plumes from the Asian continent. (author)

  15. Observation of monopole strength in the 12C(e,e'p0)11B reaction

    International Nuclear Information System (INIS)

    Calarco, J.R.; Arruda-Neto, J.; Griffioen, K.A.; Hanna, S.S.; Hoffmann, D.H.H.; Neyer, B.; Rand, R.E.; Wienhard, K.; Yearian, M.R.

    1984-01-01

    The location of the giant monopole resonance and, therefore, the compressibility is unknown in light nuclei. The forward-backward (e, e'p) angular correlation asymmetry from 12 C has been measured and found to be very sensitive to monopole strength in the giant dipole resonance region. Similar reactions will, thus, provide a sensitive tool in the search for monopole strength in light nuclei. (orig.)

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

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

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

  17. Irradiation Effects in Fortiweld Steel Containing Different Boron Isotopes

    International Nuclear Information System (INIS)

    Grounes, M.

    1967-07-01

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

  18. Irradiation Effects in Fortiweld Steel Containing Different Boron Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Grounes, M

    1967-07-15

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

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

    Science.gov (United States)

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

    2013-04-01

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

  20. Boron isotopes at the catchment scale, a new potential tool to infer critical zone processes.

    Science.gov (United States)

    Gaillardet, J.; Noireaux, J.; Braun, J. J.; Riotte, J.; Louvat, P.; Bouchez, J.; Lemarchand, D.; Muddu, S.; Mohan Kumar, M.; Candaudap, F.

    2017-12-01

    Boron is a mid-mass element that has two isotopes, 10B and 11B. These isotopes are largely fractioned by a number of chemical, biological and physical processes. Boron as a great affinity for clays and is useful for life, making it a double tracer of critical zone processes. This study focuses on the Mule Hole Critical Zone Observatory in South India. This is part of the French Research Infrastructure OZCAR and has benefited from the fruitful Indo-French collaboration (Indo-French Cell for Water Sciences) for more that 15 years. Boron and its isotopes were measured in the different compartment of the CZ in Mule Hole, vegetation, atmosphere, throughfall, soil, soil water, river water and compared to the behavior of other elements. The well constrained hydrology in Mule Hole allowed us to calculate the main fluxes affecting boron in the Critical Zone and came to the first order conclusion that the recycling of boron by vegetation is by far the most important flux within the system, reaching 15-20 times the catchment outlet flux. From an isotopic point of view, the total range of variation is measured between -3 ‰ and 77‰, with a bedrock value at 10‰ in classical delta unit, making boron a well suited tracer for constraining CZ processes. The flux of boron most enriched in heavy boron is the throughfall, showing the importance of biological processes in controlling the boron isotopic composition of the stream. Boron in soils in depleted in the heavy isotope but is enriched in boron compared to the bedrock, a surprising situation that we interpret as the legacy of a previous stage of transient weathering. These results indicate a strong decoupling between the behaviors of boron at the surface of the CZ and at depth.

  1. Study of the (d,α) reactions on the nuclei 10B, 11B, 12C, and 13C and the reaction 13C(p,α)10B and their microscopic and semicroscopic analysis

    International Nuclear Information System (INIS)

    Abd el-Kariem, S.E.S.

    1984-01-01

    In the framework of a systematic analysis of many-particle transfer reactions on light nuclei in the present thesis the two-particle transfer reactions of the type (d,α) on the nucleus 10 B at Esub(d) = 16 MeV and on the nuclei 11 B, 12 C and 13 C at Esub(d) = 24 MeV as well as the three-particle transfer reaction 13 C(p,α) 10 B at eight incident energies between 16 and 45 MeV have been studied. In the case of the residual nuclei 10 B and 11 B transitions up to an excitation energy Esub(x) approx.= 7.5 respectively approx.= 9,0 MeV, in the case of the residual nuclei 8 Be and 9 Be transitions up to Esub(x) approx.= 17 respectively 2.5 MeV were evaluated. Under the assumption that the studied reactions behave as direct one-stage transfer processes the measurement results were analyzed in the framework of the DWBA theory in zero-range approximation. The parameters for the optical potentials used in the DWBA calculations were taken from literature and partly modified by fitting to the angular distributions of the reactions studied here. Microscopic and semimicroscopic calculations were performed. In the semimicroscopic calculations the spectroscopic amplitudes calculated microscopically or in SU(3) approximation were used together with a cluster form factor, in the other case with a microscopically calculated form factor. For the residual nucleus for some higher excited states results on spin, parity, and isospin could be partly obtained, partly confirmed. (orig./HSI) [de

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-01

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

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

    International Nuclear Information System (INIS)

    Jouvet, Fabien; Roux, Sylvie; Carabasse, Stephanie; Felgines, Didier

    2012-09-01

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

  4. Deposition of Boron in Possible Evaporite Deposits in Gale Crate

    Science.gov (United States)

    Gasda, P. J.; Peets, E.; Lamm, S. N.; Rapin, W.; Lanza, N.; Frydenvang, J.; Clark, B. C.; Herkenhoff, K. E.; Bridges, J.; Schwenzer, S. P.; Haldeman, E. B.; Wiens, R. C.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; Bodine, M. R.; McInroy, R.

    2017-12-01

    Boron has been previously detected in Gale crater using the ChemCam instrument on board the NASA Curiosity rover within calcium sulfate fracture fill hosted by lacustrine mudstone and eolian sandstone units. Recent results show that up to 300 ppm B is present in the upper sections of the lacustrine unit. Boron has been detected in both the groundwater-emplaced calcium sulfate fracture fill materials and bedding-parallel calcium sulfate layers. The widespread bedding-parallel calcium sulfate layers within the upper strata of the lacustrine bedrock that Curiosity has encountered recently could be interpreted as primary evaporite deposits. We have two hypotheses for the history of boron in Gale crater. In both hypotheses, borates were first deposited as lake water evaporated, depositing primary evaporates that were later re-dissolved by groundwater, which redistributed the boron into secondary evaporitic calcium sulfate fracture fill deposits. In the first scenario, Gale crater may have undergone a period of perennial lake formation during a drier period of martian history, depositing layers of evaporitic minerals (including borates) among lacustrine mudstone layers. In the second scenario, lake margins could have become periodically exposed during cyclic drops in lake level and subsequently desiccated. Evaporites were deposited and desiccation features were formed in lowstand deposits. Either hypothetical scenario of evaporite deposition would promote prebiotic chemical reactions via wet-dry cycles. Boron may be an important prebiotic element, and as such, its presence in ancient martian surface and groundwater provides evidence that important prebiotic chemical reactions could occur on Mars if organics were present. The presence of boron in ancient Gale crater groundwater also provides additional evidence that a habitable environment existed in the martian subsurface well after the expected disappearance of liquid water on the surface of Mars. We will report on the

  5. Neutron-gamma discrimination of boron loaded plastic scintillator

    International Nuclear Information System (INIS)

    Wang Dong; He Bin; Zhang Quanhu; Wu Chuangxin; Luo Zhonghui

    2010-01-01

    Boron loaded plastic scintillator could detect both fast neutrons thanks to hydrogen and thermal neutrons thanks to 10B. Both reactions have large cross sections, and results in high detection efficiency of incident neutrons. However, similar with other organic scintillators, boron loaded plastic scintillator is sensitive to gamma rays and neutrons. So gamma rays must be rejected from neutrons using their different behavior in the scintillator. In the present research zero crossing method was used to test neutron-gamma discrimination of BC454 boron loaded plastic scintillator. There are three Gaussian peaks in the time spectrum, they are corresponding to gamma rays, fast neutrons and flow neutrons respectively. Conclusion could be made that BC454 could clear discriminate slow neutrons and gamma, but the discrimination performance turns poor as the neutrons' energy becomes larger. (authors)

  6. T cell uptake for the use of boron neutron capture as an immunologic research tool

    International Nuclear Information System (INIS)

    Binello, E.; Mitchell, R.N.; Harling, O.K.

    2004-01-01

    An immunologic tool based on manipulation of the boron neutron capture reaction was previously proposed in the context of heart transplantation research to examine the temporal relationship between parenchymal rejection (representing immune cell infiltration) and transplantation-associated arteriosclerosis (characterized by progressive vascular occlusion). Critical to the development of this method is the uptake of boron by specific cells of the immune system, namely T cells, without adverse effects on cell function, which may be assessed by the ability of boron-loaded cells to produce IFNγ, a protein with substantial impact on rejection. This work presents the evaluation of two carboranyl thymidine analogs. Advantages of this type of boron compound are reduced risk of leakage and effective dose delivery based on their incorporation into cellular nuclear material. Results indicate that uptake of these boronated nucleosides is high with no adverse effects on cell function, thereby warranting the continued development of this technique that has potentially wide applicability in immunological models

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

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  8. Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry.; Sintesis y caracterizacion del borohidrato de alanina para su uso en dosimetria de neutrones termicos.

    Energy Technology Data Exchange (ETDEWEB)

    Yanez S, J C

    1994-07-01

    Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10{sup 7} n/cm{sup 2} s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author).

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

    International Nuclear Information System (INIS)

    Kabalka, G.W.

    1997-08-01

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

  10. Synthesis and characterization of boron trifluoride (B F[sub 3]). Sintese e caracterizacao de trifluoreto de boro (BF[sub 3])

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, E T.R.; Umeda, K; Echternacht, M V; Silva, E.F. da.

    1994-08-01

    High purity boron trifluoride (B F[sub 3]) has been prepared from reaction of ammonium fluorborate and boron oxide in concentrated sulfuric acid. Fluorborate was synthesized by reaction of ammonium bi fluoride and boric acid produced from enrichment plant. (author).

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

    International Nuclear Information System (INIS)

    Grotheer, E.W.

    1979-01-01

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

  12. Prevalence and risk factors for depressive reaction among resident survivors after the tsunami following the Great East Japan Earthquake, March 11, 2011.

    Directory of Open Access Journals (Sweden)

    Chieko Matsubara

    Full Text Available The Great East Japan Earthquake caused a gigantic tsunami which devastated coastal areas of northern Japan on 11 March 2011. Despite the large number of 'resident survivors' who continued to reside in their damaged houses on the second or upper floors, research on the mental health of these individuals has been limited. This study explored the prevalence of depressive reaction and risk factors for depressive reaction among these resident survivors.A cross-sectional household health support needs screening was conducted for resident survivors in Higashi-Matsushima city, Miyagi prefecture, two to four months after the tsunami. The health interview that was conducted including mental status, assessed by the Patient Health Questionnaire-2 (PHQ-2.Of 5,454 respondents, 8.1% had depressive reaction. After adjustment by the number of weeks from the tsunami and the mortality rate at each respondent's place of residence, depressive reaction was significantly associated with house flooding below or above the ground floor (odds ratios of 1.92, 2.36, respectively, the unavailability of gas supply (odds ratio, 1.67, being female (odds ratio, 1.47, middle aged or elderly (odds ratios of 2.41, 2.42, respectively, regular intake of psychotropic medicine(s since before the tsunami (odds ratio, 2.53 and the presence of one to five or more than six cohabiters (odds ratios of 0.61, 0.52, respectively.The results suggest a considerable psychological burden (depressive reaction following the tsunami among resident survivors. Special supports for families with psychiatric problems need to be considered among resident survivors. Restoration of lifeline utilities and the strengthening of social ties of persons living alone may help prevent depressive reaction among resident survivors after a tsunami.

  13. Prevalence and risk factors for depressive reaction among resident survivors after the tsunami following the Great East Japan Earthquake, March 11, 2011.

    Science.gov (United States)

    Matsubara, Chieko; Murakami, Hitoshi; Imai, Koubun; Mizoue, Tetsuya; Akashi, Hidechika; Miyoshi, Chiaki; Nakasa, Tamotsu

    2014-01-01

    The Great East Japan Earthquake caused a gigantic tsunami which devastated coastal areas of northern Japan on 11 March 2011. Despite the large number of 'resident survivors' who continued to reside in their damaged houses on the second or upper floors, research on the mental health of these individuals has been limited. This study explored the prevalence of depressive reaction and risk factors for depressive reaction among these resident survivors. A cross-sectional household health support needs screening was conducted for resident survivors in Higashi-Matsushima city, Miyagi prefecture, two to four months after the tsunami. The health interview that was conducted including mental status, assessed by the Patient Health Questionnaire-2 (PHQ-2). Of 5,454 respondents, 8.1% had depressive reaction. After adjustment by the number of weeks from the tsunami and the mortality rate at each respondent's place of residence, depressive reaction was significantly associated with house flooding below or above the ground floor (odds ratios of 1.92, 2.36, respectively), the unavailability of gas supply (odds ratio, 1.67), being female (odds ratio, 1.47), middle aged or elderly (odds ratios of 2.41, 2.42, respectively), regular intake of psychotropic medicine(s) since before the tsunami (odds ratio, 2.53) and the presence of one to five or more than six cohabiters (odds ratios of 0.61, 0.52, respectively). The results suggest a considerable psychological burden (depressive reaction) following the tsunami among resident survivors. Special supports for families with psychiatric problems need to be considered among resident survivors. Restoration of lifeline utilities and the strengthening of social ties of persons living alone may help prevent depressive reaction among resident survivors after a tsunami.

  14. Analysis of longitudinal momentum distribution of 10Be in 9Be(11Be, 10Be)X reaction

    International Nuclear Information System (INIS)

    Singh, Monika; Kharab, Rajesh; Singh, Ram Mehar

    2013-01-01

    We have analyzed the longitudinal momentum distribution of 10 Be fragment coming from one neutron stripping from 11 Be on 9 Be target at 60AMeV beam energy within the framework of zero and first order eikonal approximation. It has been found that the inclusion of first order correction term in the eikonal approximation results in a substantial improvement in the matching between the predicted and experimental results especially in tail region of the spectrum. (author)

  15. Contribution to the study of (d,p) and (d,{alpha}> reactions on {sup 16}O and {sup 11}B from 200 keV to 1 MeV; Contribution a l'etude des reactions (d,p) et (d,{alpha}) sur {sup 16}O et {sup 11}B de 200 keV a 1 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Longequeue, N [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-05-01

    The reactions {sup 16}O(d,{alpha}{sub 0}), (d,p{sub 0}), (d,p{sub 1}) and {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) have been studied from 200 keV to 1 MeV. The interpretation of (d,{alpha}) reactions by the compound nucleus theory has shown the presence of {sup 18}F levels (7,94 MeV, 1+; 8,09 MeV, 1+ ) and of {sup 13}C level (19 MeV, 3/2{+-} or 5/2-). The interpretation of {sup 16}O(d,p{sub 1}) and {sup 11}B(d,p{sub 0}) reactions at energies lower than 400 keV has been given by a theory of Coulomb stripping. (author) [French] L'etude experimentale des reactions {sup 16}O(d,{alpha}{sub 0}); (d,p{sub 0}), (d,p{sub 1}) et {sup 11}B(d,{alpha}{sub 0}), (d,{alpha}{sub 2}), (d,p{sub 0}) a ete faite de 200 keV a 1 Mev. L'interpretation des reactions (d,a) par la theorie du noyau compose a permis la mise en evidence de niveaux du {sup 18}F (7,94 MeV, 1+; 8,09MeV, 1+ ) et du {sup 13}C(19 MeV, 3/2{+-} ou 5/2-). L'interpretation des reactions {sup 16}O(d,p{sub 1}) et {sup 11}B(d,p{sub 0}), a basse energie (< 400 keV), par une theorie de stripping de Coulomb, a ete donnee.

  16. Post-traumatic stress reactions following the March 11, 2004 terrorist attacks in a Madrid community sample: a cautionary note about the measurement of psychological trauma.

    Science.gov (United States)

    Vázquez, Carmelo; Pérez-Sales, Pau; Matt, Georg

    2006-05-01

    Posttraumatic stress reactions related to the Madrid March 11, 2004, terrorist attacks were examined in a sample of Madrid residents (N = 503) 18-25 days after the attacks, using multiple diagnostic criteria and different cut-off scores. Based on the symptoms covered by the Posttraumatic Stress Disorder Checklist-Civilian (PCL-C; Weathers, Litz, Herman, Huska, and Keane, 1993), rates of probable posttraumatic stress disorder (PTSD) ranged from 3.4% to 13.3%. Taking into account additional criteria from the Diagnostic and Statistical Manual of Mental Disorders (American Psychiatric Association, 200; i.e., the impact of initial reaction and problems in daily functioning as a consequence of the traumatic event), only 1.9% of respondents reported probable PTSD. These results suggest that inferences about the impact of traumatic events on the general population are strongly influenced by the definition of traumatic response. Our findings also revealed that the magnitude of posttraumatic reactions is associated with several risk factors, including living close to the attacked locations, physical proximity to the attacks when they occurred, perception of one's life being at risk, intensity of initial emotional reactions, and being a daily user of the attacked train lines. The use of different cut-off scores did not affect the pattern of risk to develop traumatic stress. The implications of these results for public health policies related to terrorist attacks are discussed.

  17. The photochemical reaction of 1,1-dicyano-3-phenylbut-1-ene. Simultaneous occurrence of p-methane and di-p-methane rearrangements

    Directory of Open Access Journals (Sweden)

    Silva Francisco A. da

    1999-01-01

    Full Text Available The direct photolysis of 1,1-dicyano-3-phenylbut-1-ene (3-MDCN was investigated at room temperature in solvents of different polarities (hexane, dichloromethane and acetonitrile. Cyclopropanes arising from both the di-pi-methane and pi-methane (1,2-H migration processes were obtained as photoproducts. The structures of the products were elucidated by ¹H-NMR, GC/MS, IR and chromatography. Relative quantum yield determination and GC analysis of sequential irradiations gave evidence that: i no secondary reactions occur, even at high conversions; ii the di-pi-methane rearrangement is significantly more affected by the solvent variation than the pi-methane reaction. Photosensitization with acetophenone or acetone did not yield any observable products. The existence of the simultaneous mechanisms and the observed effects were considered as evidence of a possible differentiation between localized and delocalized excitation on the excited state surface.

  18. 11C-radioisotope study of methanol co-reaction with ethanol over Ni-MCM-41 silica-alumina and Ni-alumina

    International Nuclear Information System (INIS)

    Sarkadi-Priboczki, E.; Kovacs, Z.; Tsoncheva, T.; Kumar, N.; Murzin, D.Yu.

    2009-01-01

    Complete text of publication follows. The Ni modifies the properties of acidic alumina and light acidic MCM-41 silica-alumina supports. The radioisotopic method is a suitable tool for distinction of the 11 Cradioisotopic methanol and its co-derivates from derivates of non-radioactive ethanol on these catalysts. Experimental. The Ni/A l 2O 3 (5 wt % Ni) is commercially available while H-MCMN-41 (Si/Al=20) and Ni-ion-exchanged MCM-41 silica-alumina (5 wt % Ni) were prepared and characterized in previous works. Before catalysis the Ni/Al 2 O 3 and Ni-MCM-41 were pre-reduced. The 11 C-methanol was formed by a radiochemical process from 11 C-carbon dioxide produced at cyclotron (T 1/2 = 20.4 min). The mixture of equivalent volume of radioactive methanol and non-radioactive ethanol was introduced into glass tube micro-flow reactor at ambient temperature. After adsorption, the valves were closed and the catalyst was heated up to the required temperatures. The desorption rate of the remaining 11 C-derivatives on catalysts were continuously followed by radiodetectors and the derivatives of methanol with ethanol were analyzed by Radio/FID-gas chromatography (FID is coupled on-line with a radiodetector). The ethanol and its derivates were identified by FID while the 11 C-methanol and its co-derivates (with ethanol) were detected by both of FID and radiodetector. Results The 11 C-dimethyl ether was the common product of the single 11 C-methanol transformation on H-MCM-41, Ni-MCM-41 and Ni- Al 2 O 3 at low temperature (200-280 degC) due to middle strong acid sites. At higher temperature (280-350 degC), the dimethyl ether and hydrocarbons were the dominant products on H-MCM-41 while dimethyl ether selectivity decreased on Ni-alumina and Ni-MCM-41 in favor of methane. The selectivities of methanol to formaldehyde and methane were the highest on Ni-MCM-41. During co-reaction of 11 C-methanol with non-radioactive ethanol, the 11 C-labeled coethers, namely 11 C-methyl ethyl ether

  19. Recoil measurement of the 12C(π(,πN))11C reaction between 90 and 350 MeV

    International Nuclear Information System (INIS)

    Porile, N.T.; Caretto, A.A.; Dropesky, B.J.; Orth, C.J.; Liu, L.C.; Giesler, G.C.

    1984-01-01

    The effective forward, perpendicular, and backward ranges of 11 C produced in the interaction of 90--350 MeV π +- with carbon have been measured using conventional thick-target thick-catcher activation techniques. With increasing pion energy, the forward ranges decrease, the backward ranges increase, and the perpendicular ranges remain essentially unchanged. However, these trends are much more pronounced for π - than for π + . The results have been compared with an intranuclear cascade code. The ratios of calculated effective ranges for π - and π + bombardment show the same energy dependence as observed experimentally

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

    International Nuclear Information System (INIS)

    Itagaki, Takaharu; Kosuge, Masao; Fukuda, Junji; Fujii, Yasuhiko.

    1992-01-01

    Ion exchange separation of boron isotopes (B-10 and B-11) has been studied by using a special boron selective ion exchange resin; NMG (n-methyl glucamine)-type anion exchange resin. The resin has shown a large isotope separation coefficient of 1.02 at the experimental conditions of temperature, 80degC, and boric acid concentration, 0.2 M (mole/dm 3 ). Enriched B-10 (92%) was obtained after the migration of 1149 m by a recyclic operation of ion exchange columns in a merry-go-round method. (author)

  1. 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)

  2. Student Research in Rocket and Plume-Reaction Kinetics

    National Research Council Canada - National Science Library

    Fontijn, Arthur

    1998-01-01

    Semi-empirical configuration interaction (SECI) theory has been extended to predict activation barriers for combustion reactions of boron group halide oxidation reactions, Good agreement with experiments has been obtained...

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

    International Nuclear Information System (INIS)

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

    1984-12-01

    The thermoelectric properties, that is the Seebeck coefficient, and electrical and thermal conductivity, of doped β-boron have been measured from 300 to 1600 K. Most of the useful doping elements are transition metals and occupy interstitial sites in the lattice. The highest figure of merit so far achieved at 1000 K is ZT = 0.11 for P-type, polycrystalline, hot-pressed β-boron doped with copper. Higher values may be achievable once a better P-type dopant is found. Some experiments on B 68 Y, α-B 12 Al, B 4 C, and B 6 Si are described. Transition metals appear to be effective dopants for B 68 Y and B 4 C

  4. Scope and Mechanism of a True Organocatalytic Beckmann Rearrangement with a Boronic Acid/Perfluoropinacol System under Ambient Conditions.

    Science.gov (United States)

    Mo, Xiaobin; Morgan, Timothy D R; Ang, Hwee Ting; Hall, Dennis G

    2018-04-18

    Catalytic activation of hydroxyl functionalities is of great interest for the production of pharmaceuticals and commodity chemicals. Here, 2-alkoxycarbonyl- and 2-phenoxycarbonyl-phenylboronic acid were identified as efficient catalysts for the direct and chemoselective activation of oxime N-OH bonds in the Beckmann rearrangement. This classical organic reaction provides a unique approach to prepare functionalized amide products that may be difficult to access using traditional amide coupling between carboxylic acids and amines. Using only 5 mol % of boronic acid catalyst and perfluoropinacol as an additive in a polar solvent mixture, the operationally simple protocol features mild conditions, a broad substrate scope, and a high functional group tolerance. A wide variety of diaryl, aryl-alkyl, heteroaryl-alkyl, and dialkyl oximes react under ambient conditions to afford high yields of amide products. Free alcohols, amides, carboxyesters, and many other functionalities are compatible with the reaction conditions. Investigations of the catalytic cycle revealed a novel boron-induced oxime transesterification providing an acyl oxime intermediate involved in a fully catalytic nonself-propagating Beckmann rearrangement mechanism. The acyl oxime intermediate was prepared independently and was subjected to the reaction conditions. It was found to be self-sufficient; it reacts rapidly, unimolecularly without the need for free oxime. A series of control experiments and 18 O labeling studies support a true catalytic pathway involving an ionic transition structure with an active and essential role for the boronyl moiety in both steps of transesterification and rearrangement. According to 11 B NMR spectroscopic studies, the additive perfluoropinacol provides a transient, electrophilic boronic ester that is thought to serve as an internal Lewis acid to activate the ortho-carboxyester and accelerate the initial, rate-limiting step of transesterification between the precatalyst

  5. A pulse radiolysis study of the reaction of hydroxyl radicals with trans-dihydroxo(1,4,8,11-tetraazacyclotetradecane)chromium(3)

    International Nuclear Information System (INIS)

    Moensted, O.; Nord, G.; Pagsberg, P.

    1987-01-01

    Hydroxyl radicals react rapidly with the title chromium(III) complex. In weakly alkaline solution, around pH≅ the product rearranges by a first-order process followed by a second-order process. This sequence is interpreted as the formation of a chromium(IV) complex which then forms a μ-peroxochromium(III) dimer. The dimer decomposes by a two-electron oxidation of the macrocyclic ligan with the concomitant formation of a double bond. In more strongly basic solution and also in dilute acid, the decay kinetics are more complicated. Supplementary measurements using trans-difluoro(1,4,8,11-tetraazacyclotetradecane)Chromium(III), which does not contain coordinated hydroxide, and cis-dihydroxo(rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane)-chromium(III), for which dimerization is sterically hindered, support the above interpretation of the consecutive reactions for the title complex. (author)

  6. Neutron Damage in Steels Containing Small Amounts of Boron

    Energy Technology Data Exchange (ETDEWEB)

    Myers, H P

    1961-05-15

    Certain low alloy steels contain small amounts (0.003 to 0.007 w/o) of boron which element contributes to the development of the air hardening properties of these steels. Such steels appear attractive for reactor pressure vessel construction but the question arises whether they will, due to the (n,{alpha}) reaction in boron, be more susceptible to neutron radiation damage than other steels which do not contain boron. We have attempted to estimate the importance of damage arising through boron fission relative to that caused by fast neutrons by assuming that the two sources of damage will be proportional to the numbers of displaced atoms produced in the two processes when no annealing or re combination of defects occurs. Within the approximations used we conclude that in a neutron spectrum which may be represented by an equivalent thermal flux {phi}{sub t} and an equivalent fast flux at 1 MeV of {phi}{sub f}, then D, the ratio of damage to boron fission to that caused by fast neutrons, is D = 4.5 x 10{sup -2} {phi}{sub t}/{phi}{sub f} (for 0. 003 w/o B). For the conditions at the inside of the reactor tank to R3 this would imply D = 1.2 x 10{sup -2} , i.e. if the R3 tank were built with a steel containing 0.003 w/o B then damage due to boron fission would be only {approx} 1 % of that caused by fast neutrons. Further problems with such steels as here discussed are the probability of embrittlement due to the introduction of boron fission fragments lithium and helium and the possibility of a radiation enhanced diffusion of boron which might lead to accentuated slow strain rate embrittlement. We argue that none of these problems should arise. It is concluded that a constructional steel containing 0.003 to 0.007 w/o B should not on this account be more susceptible to radiation damage than other non boron containing steels.

  7. Temperature escalation in PWR fuel rod simulators due to the zircaloy/steam reaction ESSI-4 ESSI-11

    International Nuclear Information System (INIS)

    Hagen, S.; Kapulla, H.; Malauscheck, H.; Wallenfels, K.P.; Buescher, B.J.

    1985-03-01

    The tests had the initial heatup rate as main parameter. The experimental arrangement consisted of a fuel rod simulator (central tungsten heater, UO 2 ring pellets and zircaloy cladding), a zircaloy shroud and the fiber ceramic insulation. A steam flow of ca. 20 g/min was introduced at the lower end of the bundle. A temperature escalation was observed in every test. The maximum cladding surface temperature in the single rod tests never exceeded 2200 0 C. The escalation began in the upper region of the rods and moved down the rods, opposite to the direction of steam flow. For fast initial heatup rates, the runoff of molten zircaloy was a limiting process for the escalation. For slow heatup rates, the formation of a protective oxide layer reduced the reaction rate. The test with less insulation thickness showed a reduction of the escalation. A stronger influence was found for the gap between shroud and insulation. This is caused by convection heat losses to the steam circulating in this gap by natural convection. Removal of the gap between shroud and insulation in essentially the same experimental arrangement produced a faster escalation. The posttest appearance of the fuel rod simulators showed that, at slow heatup rates oxidation of the cladding was complete, and the fuel rod was relatively intact. Conversely, at fast heatup rates, relatively little cladding oxidation with extensive dissolution of the UO 2 pellets and runoff of molten cladding was observed. (orig./HP) [de

  8. Study of two-step mechanisms in the 12C(p,d)11C reaction at 45 MeV

    International Nuclear Information System (INIS)

    Couvert, Pierre.

    1974-01-01

    An attempt was made to find the nuclear reaction mechanisms explaining the intensity and behavior of the cross sections in the 12 C(p,d) 11 C reaction at 45 MeV. First, the conventional interpretation of the experimental data leads to two closely related conclusions. The behavior of the cross-sections measured cannot be explained without including the intermediate stage of collective 2 + 12 C excitation or accounting for its possible interference with the direct capture of a neutron. The relative intensity of the different mechanisms is directly bound up with the value of the nuclear structure parameters of the wave function adopted. As a result this study is found to be an excellent wave function test and the results obtained seem to prove that the wave function calculated by Clegg for 11 B is also suitable for 11 C. Next a two-stage process was introduced, using inelastic deuteron scattering on 11 C as the intermediate stage. The problem which then arises is to determine the deformation parameters of the final nucleus in its different excitation states. The model adopted is in fact very crude and only gives quantitative information on the physical reality of such a process. Some improvement is shown to be obtained by finite range and non-local potential corrections. It is observed that track-transitions, which correspond in fact to new processes interfering with those already introduced play an important part. The most realistic way to treat the problem is thus to make an exact calculation within the coupled equation system, keeping strictly to physically justified hypotheses [fr

  9. Note on boron toxicity in oats

    Energy Technology Data Exchange (ETDEWEB)

    Langille, W M; Mahoney, J F

    1959-01-01

    Boron was applied at the rate of 35 pounds per acre of borax to a field of oats. With the first noticeable growth there appeared a definite chlorotic condition of the oat seedlings on plots receiving boron treatments. Analysis of chlorotic tissue at 3 weeks after seeding indicated 110 ppm boron, while apparently healthy tissue contained 6.1 ppm boron at the same stage of growth. There was a rapid decline in the boron content of the oat tissue as the crop grew older. At maturity the oat tissue from the boron-treated plots contained an average of 14.15 ppm boron as compared with 4.10 boron from untreated areas. Boron toxicity had no harmful effect so far as yields were concerned, under the conditions of this experiment. 3 references.

  10. Method for producing polycrystalline boron nitride

    International Nuclear Information System (INIS)

    Alexeevskii, V.P.; Bochko, A.V.; Dzhamarov, S.S.; Karpinos, D.M.; Karyuk, G.G.; Kolomiets, I.P.; Kurdyumov, A.V.; Pivovarov, M.S.; Frantsevich, I.N.; Yarosh, V.V.

    1975-01-01

    A mixture containing less than 50 percent of graphite-like boron nitride treated by a shock wave and highly defective wurtzite-like boron nitride obtained by a shock-wave method is compressed and heated at pressure and temperature values corresponding to the region of the phase diagram for boron nitride defined by the graphite-like compact modifications of boron nitride equilibrium line and the cubic wurtzite-like boron nitride equilibrium line. The resulting crystals of boron nitride exhibit a structure of wurtzite-like boron nitride or of both wurtzite-like and cubic boron nitride. The resulting material exhibits higher plasticity as compared with polycrystalline cubic boron nitride. Tools made of this compact polycrystalline material have a longer service life under impact loads in machining hardened steel and chilled iron. (U.S.)

  11. Analysis and separation of boron isotopes; Analyse et separation des isotopes du bore

    Energy Technology Data Exchange (ETDEWEB)

    Perie, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-11-01

    The nuclear applications of boron-10 justify the study of a method of measurement of its isotopic abundance as well as of very small traces of boron in different materials. A systematic study of thermionic emission of BO{sub 2}Na{sub 2}{sup +} has been carried out. In the presence of a slight excess of alkalis, the thermionic emission is considerably reduced. On the other hand, the addition of a mixture of sodium hydroxide-glycerol (or mannitol) to borax permits to obtain an intense and stable beam. These results have permitted to establish an operative method for the analysis of traces of boron by isotopic dilution. In other respects, the needs of boron-10 in nuclear industry Justify the study of procedures of separation of isotopes of boron. A considerable isotopic effect has been exhibited in the chemical exchange reaction between methyl borate and borate salt in solution. In the case of exchange between methyl borate and sodium borate, the elementary separation factor {alpha} is: {alpha}=(({sup 11}B/{sup 10}B)vap.)/(({sup 11}B/{sup 10}B)liq.)=1.03{sub 3}. The high value of this elementary effect has been multiplied in a distillation column in which the problem of regeneration of the reactive has been resolved. An alternative procedure replacing the alkali borate by a borate of volatile base, for example diethylamine, has also been studied ({alpha}=1,02{sub 5} in medium hydro-methanolic with 2,2 per cent water). (author) [French] Les applications nucleaires du bore 10 justifient l'etude d'une methode de mesure de son abondance isotopique dans divers materiaux ainsi que le dosage de tres faibles traces de bore. Une etude systematique de l'emission thermoionique de BO{sub 2} Na{sub 2}{sup +} a ete effectuee. En presence d'un leger exces d'alcalins, l'emission thermoionique est considerablement reduite. Par contre l'addition au borax d'un melange soude-glycerol (ou mannitol) permet d'obtenir un faisceau stable et intense. Ces resultats ont permis d'etablir un mode

  12. 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

  13. AUTOCATALYTIC REDUCTION AND CHARACTERISTICS OF BORON-CONTAINING COATINGS

    Directory of Open Access Journals (Sweden)

    V. Covaliov

    2013-06-01

    Full Text Available The research results of the plating conditions, chemical composition and properties of Ni-B coatings and Ni-Re-B, Ni-Mo-B and Ni-W-B alloys are given. It was shown that introduction of alloying elements (Re, Мо and W in the composition of Ni-containing coatings modifies the catalytic activity of the alloys’ surface, with regard to the parallel reactions of dimethylamino-borane (DMAB heterogeneous hydrolysis, Ni reduction and evolving of the molecular hydrogen. It was found that with the increase in concentration of alloying element, boron content in the coatings is decreased to the trace amounts. The effect of alloys composition on hydrogen evolving overvoltage was studied. Due to the low overvoltage of hydrogen evolving (HE on the alloy Ni-Re-B surface (11 at.% Re, it can be used as electrode for hydrogen generation from water in the electrolytic cell with novel design and improved technical-economic indicators.

  14. 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.

  15. Lactobacillus rhamnosus R11 consumed in a food supplement survived human digestive transit without modifying microbiota equilibrium as assessed by real-time polymerase chain reaction.

    Science.gov (United States)

    Firmesse, Olivier; Mogenet, Agnès; Bresson, Jean-Louis; Corthier, Gérard; Furet, Jean-Pierre

    2008-01-01

    The aim of this study was to evaluate the survival of Lactobacillus rhamnosus R11 and Lactobacillus acidophilus R52 in the human digestive tract and their effects on the microbiota homeostasis. We designed an open human trial including 14 healthy volunteers. A 3-week exclusion period of fermented products was followed by a 12-day consumption period of 4 capsules daily containing 2 x 10(9)L. rhamnosus R11 and 1 x 10(8)L. acidophilus R52, and a 12-day wash-out period. The 2 strains and dominant bacterial groups of the microbiota were quantified by real-time polymerase chain reaction. At the end of the capsule consumption period, high levels of L. rhamnosus R11 were detected in faecal samples from all volunteers, reaching a mean value of 7.1 log(10) colony-forming unit (CFU) equivalents/g of stool. L. acidophilus R52 was detected in the stools of only 1 volunteer, reaching a maximum level of 6.1 log(10) CFU equivalents/g of stool. Dilution plating enumerations performed in parallel provided less consistent and generally lower levels. No significant effect of capsule consumption was observed on microbiota homeostasis for the dominant faecal populations. Mean values of 8.8, 9.2, 9.9 and 10.6 log(10) CFU equivalents/g of stool were obtained for the Clostridium coccoides, Bifidobacterium sp., Bacteroides sp. and Clostridium leptum groups, respectively.

  16. Modeling the suppression of boron transient enhanced diffusion in silicon by substitutional carbon incorporation

    Science.gov (United States)

    Ngau, Julie L.; Griffin, Peter B.; Plummer, James D.

    2001-08-01

    Recent work has indicated that the suppression of boron transient enhanced diffusion (TED) in carbon-rich Si is caused by nonequilibrium Si point defect concentrations, specifically the undersaturation of Si self-interstitials, that result from the coupled out-diffusion of carbon interstitials via the kick-out and Frank-Turnbull reactions. This study of boron TED reduction in Si1-x-yGexCy during 750 °C inert anneals has revealed that the use of an additional reaction that further reduces the Si self-interstitial concentration is necessary to describe accurately the time evolved diffusion behavior of boron. In this article, we present a comprehensive model which includes {311} defects, boron-interstitial clusters, a carbon kick-out reaction, a carbon Frank-Turnbull reaction, and a carbon interstitial-carbon substitutional (CiCs) pairing reaction that successfully simulates carbon suppression of boron TED at 750 °C for anneal times ranging from 10 s to 60 min.

  17. Modeling the suppression of boron transient enhanced diffusion in silicon by substitutional carbon incorporation

    International Nuclear Information System (INIS)

    Ngau, Julie L.; Griffin, Peter B.; Plummer, James D.

    2001-01-01

    Recent work has indicated that the suppression of boron transient enhanced diffusion (TED) in carbon-rich Si is caused by nonequilibrium Si point defect concentrations, specifically the undersaturation of Si self-interstitials, that result from the coupled out-diffusion of carbon interstitials via the kick-out and Frank--Turnbull reactions. This study of boron TED reduction in Si 1-x-y Ge x C y during 750 o C inert anneals has revealed that the use of an additional reaction that further reduces the Si self-interstitial concentration is necessary to describe accurately the time evolved diffusion behavior of boron. In this article, we present a comprehensive model which includes {311} defects, boron-interstitial clusters, a carbon kick-out reaction, a carbon Frank--Turnbull reaction, and a carbon interstitial-carbon substitutional (C i C s ) pairing reaction that successfully simulates carbon suppression of boron TED at 750 o C for anneal times ranging from 10 s to 60 min. copyright 2001 American Institute of Physics

  18. Solid-state nuclear magnetic resonance studies of phosphorus and boron in coals and combustion residues

    Energy Technology Data Exchange (ETDEWEB)

    Burchill, P.; Howarth, O.W.; Richards, D.G.; Sword, B.J. (British Coal Corporation, Stoke Orchard (UK). Coal Research Establishment)

    1990-04-01

    Solid-state nuclear magnetic resonance spectroscopy with magic angle spinning (MAS-n.m.r.) was used to study the occurrence of phosphorus and boron in coal, and their fate on combustion. These elements are only minor components of coal, but may significantly influence the utilization properties. {sup 31} P MAS-n.m.r. spectroscopy has confirmed that phosphorus is present in coal predominantly as apatite. This mineral is thermally stable under oxidizing conditions, and survives largely unaltered in high temperature ashes. However, under the semi-reducing bed conditions of certain stoker-fired boilers, it may be decomposed, volatilizing the phosphorus. The {sup 31}P MAS-n.m.r. spectra of bonded deposits show phosphorus in a markedly different coordination environment to that in apatite, the chemical shift suggesting aluminium phosphate or boron phosphate. {sup 11}B MAS-n.m.r. spectra of coals exhibit resonances due to both trigonal and tetrahedrally coordinated boron. Trigonal boron is probably present as tourmaline, but the nature of the tetrahedral boron is less certain; it may be held in tetrahedral sites within certain clay minerals. In common with phosphorus, boron may be volatilized during combustion. The {sup 11}B MAS-n.m.r. spectra of bonded deposits show a tetrahedral resonance with a chemical shift quite consistent with that of boron phosphate. 39 refs., 9 figs., 5 tabs.

  19. Study of the break reaction of Be{sup 11} on Ti{sup 48} target; the towing mode: a spectroscopic tool for the study of nuclei; Etude de la reaction de cassure du {sup 11}Be sur cible de {sup 48}Ti; le towing mode, un outil spectroscopique pour l'etude des noyaux

    Energy Technology Data Exchange (ETDEWEB)

    Lima, V

    2004-10-01

    In a towing mode reaction the projectile picks up a nucleon from the target and then breaks up by emitting one nucleon. The velocity of the emitted nucleon is boosted by the projectile velocity, leading to the emission of the nucleon in a narrow cone around the direction of the scattered projectile. This work is dedicated to the towing mode in halo nuclei such as Be{sup 11}. The experiment was performed at Ganil facility by bombarding a Ti{sup 48} target with a 41 MeV per nucleon Be{sup 11} beam, the reaction studied is: Ti{sup 48}(Be{sup 11}, Be{sup 10} + n + {gamma}). The first chapter reviews the various nuclear processes that take place when 2 nuclei collide with a particular attention for the towing mode. The second chapter is dedicated to solving the time dependant Schroedinger equation (TDSE) in order to assess the impact of various parameters such as incident energy, target charge or the linking energy of the nucleon, on the towing mode reaction. The third chapter deals with the experimental equipment and set-up including detectors and the data acquisition system. Computerized simulations have been performed in order to assess the efficiency of the detecting system, they are presented in the fourth chapter. A comparison between experimental data and the results from TDSE solving, concerning the energy spectra of the emitted particles, has enabled the author to deduce the spectroscopic factors for the different contributions of the fundamental state of Be{sup 11}, they are presented in the last chapter. The cross-sections of the towing mode are of the magnitude of several tens of milli-barns in the case of weakly bound nuclei like Be{sup 11} which make it an efficient tool to study intern structure of nuclei. (A.C.)

  20. Study of the break reaction of Be{sup 11} on Ti{sup 48} target; the towing mode: a spectroscopic tool for the study of nuclei; Etude de la reaction de cassure du {sup 11}Be sur cible de {sup 48}Ti; le towing mode, un outil spectroscopique pour l'etude des noyaux

    Energy Technology Data Exchange (ETDEWEB)

    Lima, V

    2004-10-01

    In a towing mode reaction the projectile picks up a nucleon from the target and then breaks up by emitting one nucleon. The velocity of the emitted nucleon is boosted by the projectile velocity, leading to the emission of the nucleon in a narrow cone around the direction of the scattered projectile. This work is dedicated to the towing mode in halo nuclei such as Be{sup 11}. The experiment was performed at Ganil facility by bombarding a Ti{sup 48} target with a 41 MeV per nucleon Be{sup 11} beam, the reaction studied is: Ti{sup 48}(Be{sup 11}, Be{sup 10} + n + {gamma}). The first chapter reviews the various nuclear processes that take place when 2 nuclei collide with a particular attention for the towing mode. The second chapter is dedicated to solving the time dependant Schroedinger equation (TDSE) in order to assess the impact of various parameters such as incident energy, target charge or the linking energy of the nucleon, on the towing mode reaction. The third chapter deals with the experimental equipment and set-up including detectors and the data acquisition system. Computerized simulations have been performed in order to assess the efficiency of the detecting system, they are presented in the fourth chapter. A comparison between experimental data and the results from TDSE solving, concerning the energy spectra of the emitted particles, has enabled the author to deduce the spectroscopic factors for the different contributions of the fundamental state of Be{sup 11}, they are presented in the last chapter. The cross-sections of the towing mode are of the magnitude of several tens of milli-barns in the case of weakly bound nuclei like Be{sup 11} which make it an efficient tool to study intern structure of nuclei. (A.C.)

  1. 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

  2. Possible application of boron neutron capture therapy to canine osteosarcoma

    International Nuclear Information System (INIS)

    Takeuchi, Akira

    1985-01-01

    Possibility for successful treatment of canine osteosarcoma by boron neutron capture therapy (BNCT) was demonstrated based upon an uptake study of the boron compound and an experimental treatment by BNCT. In the up take study following intravenous administration of Na 2 B 12 H 11 SH, satisfactorily higher boron concentration with some variation between tumors is likely to be obtained 12 hours after the administration, together with significantly lower boron levels in blood and bone. Based upon these results, osteosarcoma of a mongrel dog was successfully treated by BNCT. The tumor received approximately 3800 rads with single neutron irradiation (approximately 1.4 x 10 13 n./cm 2 ) about 12 hours after intravenous infusion of Na 2 B 12 H 11 SH of 96 % enriched 10 B in the ratio of 50 mg 10 B/kg. Clinical and radiographical improvements were remarkable and no neoplastic cell was found in any part of the original neoplastic lesion and its surrounding tissue at the time of autopsy after 30 days. (author)

  3. Effect of boron nitride coating on fiber-matrix interactions

    International Nuclear Information System (INIS)

    Singh, R.N.; Brun, M.K.

    1987-01-01

    Coatings can modify fiber-matrix reactions and consequently interfacial bond strengths. Commercially available mullite, silicon carbide, and carbon fibers were coated with boron nitride via low pressure chemical vapor deposition and incorporated into a mullite matrix by hot-pressing. The influence of fiber-matrix interactions for uncoated fibers on fracture morphologies was studied. These observations are related to the measured values of interfacial shear strengths

  4. Copper atoms embedded in hexagonal boron nitride as potential catalysts for CO oxidation: A first-principles investigation

    KAUST Repository

    Liu, Xin

    2014-01-01

    We addressed the electronic structure of Cu atoms embedded in hexagonal boron nitride (h-BN) and their catalytic role in CO oxidation by first-principles-based calculations. We showed that Cu atoms prefer to bind directly with the localized defects on h-BN, which act as strong trapping sites for Cu atoms and inhibit their clustering. The strong binding of Cu atoms at boron vacancy also up-shifts the energy level of Cu-d states to the Fermi level and promotes the formation of peroxide-like intermediate. CO oxidation over Cu atoms embedded in h-BN would proceed through the Langmuir-Hinshelwood mechanism with the formation of a peroxide-like complex by reaction of coadsorbed CO and O2, with the dissociation of which the a CO2 molecule and an adsorbed O atom are formed. Then, the embedded Cu atom is regenerated by the reaction of another gaseous CO with the remnant O atom. The calculated energy barriers for the formation and dissociation of peroxide complex and regeneration of embedded Cu atoms are as low as 0.26, 0.11 and 0.03 eV, respectively, indicating the potential high catalytic performance of Cu atoms embedded in h-BN for low temperature CO oxidation. © the Partner Organisations 2014.

  5. High-performance liquid chromatographic method to evaluate the hydrogen atom transfer during reaction between 1,1-diphenyl-2-picryl-hydrazyl radical and antioxidants

    International Nuclear Information System (INIS)

    Boudier, Ariane; Tournebize, Juliana; Bartosz, Grzegorz; El Hani, Safae; Bengueddour, Rachid; Sapin-Minet, Anne; Leroy, Pierre

    2012-01-01

    Highlights: ► Both 1,1-diphenyl-2-picrylhydrazyl radical and its product measurement by HPLC. ► Lowest limit of detection by monitoring 1,1-diphenyl-2-picryl-hydrazine. ► Adsorption problem of the radical on HPLC parts have been pointed out. - Abstract: 1,1-Diphenyl-2-picrylhydrazyl (DPPH·) is a stable nitrogen centred radical widely used to evaluate direct radical scavenging properties of various synthetic or natural antioxidants (AOs). The bleaching rate of DPPH· absorbance at 515 nm is usually monitored for this purpose. In order to avoid the interference of complex coloured natural products used as antioxidant supplements or cosmetics, HPLC systems have been reported as alternative techniques to spectrophotometry. They also rely upon measurement of DPPH· quenching rate and none of them permits to identify and measure 1,1-diphenyl-2-picryl-hydrazine (DPPH-H), the reduced product of DPPH· resulting from hydrogen atom transfer (HAT), which is the main mechanism of the reaction between DPPH· and AOs. We presently report an HPLC method devoted to the simultaneous measurement of DPPH· and DPPH-H. Both were fully separated on a C18 column eluted with acetonitrile–10 mM ammonium citrate buffer pH 6.8 (70:30, v/v) and detected at 330 nm. Adsorption process of DPPH· onto materials of the HPLC system was pointed out. Consequently, the linearity range observed for DPPH· was restricted, thus a much lower limit of detection was obtained for DPPH-H than for DPPH· using standards (0.02 and 14 μM, respectively). The method was applied to three commonly used AOs, i.e. Trolox ® , ascorbic acid and GSH, and compared with spectrophotometry. Further application to complex matrices (cell culture media, vegetal extracts) and nanomaterials demonstrated (i) its usefulness because of higher selectivity than colorimetry, and (ii) its help to investigate the mechanisms occurring with the free radical.

  6. Adsorption of boron from boron-containing wastewaters by ion exchange in a continuous reactor

    International Nuclear Information System (INIS)

    Yilmaz, A. Erdem; Boncukcuoglu, Recep; Yilmaz, M. Tolga; Kocakerim, M. Muhtar

    2005-01-01

    In this study, boron removal from boron-containing wastewaters prepared synthetically was investigated. The experiments in which Amberlite IRA 743, boron specific resin was used were carried out in a column reactor. The bed volume of resin, boron concentration, flow rate and temperature were selected as experimental parameters. The experimental results showed that percent of boron removal increased with increasing amount of resin and with decreasing boron concentration in the solution. Boron removal decreased with increasing of flow rate and the effect of temperature on the percent of total boron removal increased the boron removal rate. As a result, it was seen that about 99% of boron in the wastewater could be removed at optimum conditions

  7. Boron exposure assessment using drinking water and urine in the North of Chile.

    Science.gov (United States)

    Cortes, S; Reynaga-Delgado, E; Sancha, A M; Ferreccio, C

    2011-12-01

    Boron is an essential trace element for plants and humans however it is still an open question what levels of boron are actually safe for humans. This study, conducted between 2006 and 2010, measured exposure levels of boron in drinking water and urine of volunteers in Arica, an area in the North of Chile with high levels of naturally occurring boron. Samples were taken of tap and bottled water (173 and 22, respectively), as well as urine from 22 volunteers, and subsequently analyzed by inductively coupled plasma spectroscopy (ICP-OES). Boron varied in public tap water from 0.22 to 11.3mgL(-1), with a median value of 2.9mgL(-1), while concentrations of boron in bottled water varied from 0.01 to 12.2mgL(-1). Neither tap nor bottled water samples had concentrations of boron within WHO recommended limits. The concentration of boron in urine varied between 0.45 and 17.4mgL(-1), with a median of 4.28mgL(-1) and was found to be correlated with tap water sampled from the homes of the volunteers (r=0.64). Authors highly recommend that in northern Chile - where levels of boron are naturally high - that the tap and bottled water supplies be monitored in order to protect public health and that regulatory standards also be established for boron in drinking water in order to limit exposure. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. 4-Acyloxy-2,5-diphenyl-3-oxo-2,3-dihydrothiophene 1,1-dioxides as acylating agents in the Friedel-Crafts reaction

    International Nuclear Information System (INIS)

    Van Ree, T.

    1989-01-01

    The 'activated esters', 4-acyloxy-2,5-diphenyl-3-oxo-2,3-dihydrothiophene 1,1-dioxides, easily accessible from 4,6-diphenylthieno[3,4-d][1,3]dioxol-2-one 5,5-dioxide, have been found to be excellent acylating agents in the Friedel-Crafts reaction with olefins and activated aromatic compounds. In the case of the olefins, product mixtures containing β-chloroketones were treated with 1,8-diazabicyclo[5.4.0]undex-7-ene to afford the corresponding unsaturated ketones in 30 - 73% yields, whereas aromatic ketones were obtained in high yields. The activated esters react slightly faster than the corresponding alkanoyl chlorides, and form fewer by-products

  9. A review of reaction rates and thermodynamic and transport properties for an 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

    Science.gov (United States)

    Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.; Lee, Kam-Pui

    1990-01-01

    Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature.

  10. Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values

    Energy Technology Data Exchange (ETDEWEB)

    Monaghan, P; Shneor, R; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Ciofi degli-Atti, C; Cisbani, E; Cosyn, W; Craver, B; de Jager, C W; Feuerbach, R J; Folts, E; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Morita, H; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Ryckebusch, J; Saha, A; Sawatzky, B; Segal, J; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L

    2014-08-01

    The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.

  11. 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.)

  12. Compatibility of heat resistant alloys with boron carbide, (4)

    International Nuclear Information System (INIS)

    Baba, Sinichi; Saruta, Toru; Ooka, Kiichi; Tanaka, Isao; Aoyama, Isao

    1985-07-01

    This paper relates to the compatibility test of control rod sheath (Hastelloy XR alloy) and neutron absorber (boronated graphite) for the VHTR, which has been researched and developed by JAERI. The irradiation was conducted by using the OGL-1 irradiation facility in the JMTR in order to study reaction behaviour between Hastelloy XR alloy and boronated graphite as well as to determine a reaction barrier performance of refractory metal foils Nb, Mo, W and Re. Irradiation conditions were as follows. Neutron dose : 4.05 x 10 22 m -2 (E 18 m -2 (E > 0.16 pJ, 1 Mev). Helium coolant : Average temperature 855 0 C, Pressure 2.94 MPa, Total impurity concentration 400 kBq/m 3 . Irradiation time : 5.0 Ms (1390 hours). Post-irradiation examinations i.e. visual inspection, dimensional inspection, weight measurement, metallography, hardness test, morphological observations by SEM and analysis of element distributions by EPMA were carried out. In the result, reaction products of Hastelloy XR alloy were observed in the ellipsoidal form locally. These results were same as those of the out-of-pile tests. Obvious irradiation effects were not detectable but a little accelarated increase in reaction depth of Hastelloy XR alloy by heat effect of specimens was observed. The refractory metal foils had a good performance of reaction barrier between Hastelloy XR alloy and boronated graphite. Furthermore, movement of Ni, Fe and Cr in the reaction area of Hastelloy XR alloy, difference in the reaction depth of B and C, irradiation effects on diffusion coefficient, lithium production and heat effect are discussed. (author)

  13. Dielectric track detectors and their applications in boron studies

    International Nuclear Information System (INIS)

    Mysak, F.; Krejci, M.

    1982-01-01

    Examples are presented of the applications of autoradiography using plastic films in the study of the distribution of boron in metal materials and its translocation owing to diffusion annealing. Alpha radiation is induced in the material by thermal neutrons while the reaction 10 B(n,α) 7 Li is used. Diffusion processes were studied in the transition zone between the base material and the overlay in hard alloy surfacing. The metallographically treated samples were placed on cellulose nitrate films and irradiated in a reactor. Autoradiograms showed that up to an annealing temperature of 800 degC there was no notable diffusion. Only at 900 degC migration occurred of boron from the transition zone to the base material. Also studied was the distribution of boron in soldered joints of nickel heat resisting alloys. The joints were subjected to homogenization annealing and the gradual disintegration was monitored of boride phases in dependence on the temperature and duration of annealing. Inside the joint boron practically disappeared and it finally appeared in the base material outside of the initial interface. (M.D.)

  14. 10B uptake by cells for boron neutron capture synovectomy

    International Nuclear Information System (INIS)

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

    2000-01-01

    Boron Neutron Capture Synovectomy (BNCS) proposes to use the 10 B(n,α) 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 2 B 12 H 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 10 B incubation concentrations varying from 1000 to 5000 ppm: approximately 15% of the 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 10 B uptake for BNCS (with KBH) is discussed. (author)

  15. Substitution of yttrium for boron in the structure of YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Dwelk, H.; Herrmann, R.; Pruss, N.; Freude, D.; Pfeifer, H.

    1989-01-01

    The influence of boron on superconducting properties of Y 1-x B x Ba 2 Cu 3 O 7-δ with x = 0 to 0.4 is studied. The analysis of 11 B NMR spectra and measurements of electric conductivity as a function of temperature show that boron is not incorporated into the YBa 2 Cu 3 O 7-δ framework on yttrium positions. (author)

  16. Axial channeling of boron ions into silicon

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  17. Measurement and microscopic analysis of the 11B(p,p') reaction at Ep = 150 MeV. Part I: Inelastic scattering

    International Nuclear Information System (INIS)

    Hannen, V.M.; Van den Berg, A.M.; Bieber, R.K.; Harakeh, M.N.; De Huu, M.A.; Kruesemann, B.A.M.; Van der Werf, S.Y.; Woertche, H.J.; Amos, K.; Deb, P.K.; Ellinghaus, F.; Frekers, D.; Rakers, S.; Schmidt, R.; Hagemann, M.

    2001-01-01

    Cross sections and analyzing powers for the 11 B(p.p') reaction have been measured using a 150 MeV polarized proton beam from the AGOR cyclotron at KVI. For the stronger inelastic transitions, also spin-flip probabilities have been extracted. A fully microscopic distorted-wave analysis of the elastic and inelastic data has been made, using density-dependent effective interactions and input from shell-model calculations in a complete (0+2) ℎω model space for normal parity transitions and in a 1 ℎω model space for non-normal parity transitions. With the help of these model calculations spin-isovector M1 strengths for the negative-parity states at excitation energies of 2.125 MeV (J π = 1/2 - ), 4.445 MeV (J π 5/2 - ), 5.020 MeV (J π = 3/2 - ) and 8.920 MeV (J π 5/2 - ) have been extracted and compared to known Gamow-Teller strengths for the analog transitions to 11 C

  18. Nuclear-physical techniques for determination of boron distribution in pure materials

    International Nuclear Information System (INIS)

    Kadirova, M.; Jumaev, N.; Simakhin, Yu.F.; Idrisov, Kh.; Usmanova, M.M.

    2001-01-01

    To study deep boron diffusion in the complex silicon structures, consisting of interchange boron doping layers of mono- and polycrystalline silicon, separated by oxide films a technique of sidelong section by using Solid State Nuclear Track Detector (SSNTD) has been elaborated. The boron distribution determination technique is based on the detection of alpha particles from the 10B(n, )7Li reaction with cellulose nitrate film. The etched track registering cellulose nitrate film show the structure image magnified 1/sin fold. Boron concentration defined by density of the etched pits appearing on the film surface. An optical microscope analysis of the sample track-mapping image is realized by examination with closely spaced ( l < x/sin ) and largely spaced ( l x/sin ) movements. All these elaborated techniques can be used to investigate other solid matrix

  19. A novel method for boron determination in rock thin sections : first results from Ngawha

    International Nuclear Information System (INIS)

    Vickridge, I.C.

    1994-01-01

    Previous studies of boron in New Zealand rock have relied on whole rock analyses. In order to gain more detailed knowledge of the sources of boron in rocks, we have developed a nuclear probe technique based on the 1 1B(p,α) nuclear reaction. The technique performs well on powdered USGS standards down to below 10 wt. ppm, and we have applied it with a proton beam focused down to 25 x 25 micrometre on a hydrothermally unaltered greywacke from Puketona, near Ngawha, Northland. There appears to be little variation in the boron concentrations in the sedimentary groundmass, but in the veins the boron appears to be more concentrated in the prehnite than in the quartz. (author). 2 tabs., 5 figs., 14 refs

  20. In situ detection of boron by ChemCam on Mars

    Science.gov (United States)

    Gasda, Patrick J.; Haldeman, Ethan B.; Wiens, Roger C.; Rapin, William; Bristow, Thomas F.; Bridges, John C.; Schwenzer, Susanne P.; Clark, Benton; Herkenhoff, Kenneth; Frydenvang, Jens; Lanza, Nina L.; Maurice, Sylvestre; Clegg, Samuel; Delapp, Dorothea M.; Sanford, Veronica L.; Bodine, Madeleine R.; McInroy, Rhonda

    2017-09-01

    We report the first in situ detection of boron on Mars. Boron has been detected in Gale crater at levels Curiosity rover ChemCam instrument in calcium-sulfate-filled fractures, which formed in a late-stage groundwater circulating mainly in phyllosilicate-rich bedrock interpreted as lacustrine in origin. We consider two main groundwater-driven hypotheses to explain the presence of boron in the veins: leaching of borates out of bedrock or the redistribution of borate by dissolution of borate-bearing evaporite deposits. Our results suggest that an evaporation mechanism is most likely, implying that Gale groundwaters were mildly alkaline. On Earth, boron may be a necessary component for the origin of life; on Mars, its presence suggests that subsurface groundwater conditions could have supported prebiotic chemical reactions if organics were also present and provides additional support for the past habitability of Gale crater.

  1. 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

  2. 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.

  3. 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

  4. Isotope engineering of van der Waals interactions in hexagonal boron nitride

    Science.gov (United States)

    Vuong, T. Q. P.; Liu, S.; van der Lee, A.; Cuscó, R.; Artús, L.; Michel, T.; Valvin, P.; Edgar, J. H.; Cassabois, G.; Gil, B.

    2018-02-01

    Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes (10B and 11B) compared to those with the natural distribution of boron (20 at% 10B and 80 at% 11B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers in 10BN than in 11BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.

  5. Alpha shift correlation (ASC) method. Sensitivity of B-11 NMR shifts to halogen substitution in the ten-vertex nido and arachno series of boron clusters. Linear behavior of NMR effects

    Czech Academy of Sciences Publication Activity Database

    Štíbr, Bohumil

    2018-01-01

    Roč. 471, FEB (2018), s. 615-619 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GA16-01618S Institutional support: RVO:61388980 Keywords : Boranes * Dicarbaboranes * NMR shifts- B NMR correlation 11 * Sensitivity factors * Substitution effects Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 2.002, year: 2016

  6. Compatibility of heat resistant alloys with boron carbide, 5

    International Nuclear Information System (INIS)

    Baba, Shinichi; Kurasawa, Toshimasa; Endow, Taichi; Someya, Hiroyuki; Tanaka, Isao.

    1986-08-01

    This paper includes an experimental result of out-of-pile compatibility and capsule design for irradiation test in Japan Materials Testing Reactor (JMTR). The compatibility between sheath material and neutron absorber materials for control rod devices (CRD) was examined for potential use in a very high temperature reactor (VHTR) which is under development at JAERI. The purpose of the compatibility tests are preliminary evaluation of safety prior to irradiation tests. Preliminary compatibility evaluation was concerned with three items as follows : 1) Lithium effects on the penetrating reaction of Incoloy 800H alloy in contact with a mixture of boronated graphite and lithium hydroxide powders, 2) Short term tensile properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite and fracture mode analysis, 3) Reaction behavior of both alloys under transient power conditions of a VHTR. It was clear that the reaction rate constant of the Incoloy 800H alloy was accelerated by doping lithium hydroxide into the boron carbide and graphite powder. The mechanical properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite were decreased. Ultimate tensile strength and tensile ductilities at temperatures over 850 deg C were reduced, but there was no change in the proof (yield) stress. Both alloys exhibited a brittle intergranular fracture mode during transient power conditions of a VHTR and also exhibited severe penetration. Irradiation capsules for compatibility test were designed to simulate three irradiation conditions of VHTR: 1) steady state for VHTR, 2) Transient power condition, 3) Service limited life of CRD. Capsule irradiation experiments have been carried out satisfactorily and thus confirm the validity of the capsule design procedure. (author)

  7. Two-channel neutron boron meter

    International Nuclear Information System (INIS)

    Chen Yongqing; Yin Guowei; Chai Songshan; Deng Zhaoping; Zhou Bin

    1993-09-01

    The two-channel neutron boron meter is a continuous on-line measuring device to measure boron concentration of primary cooling liquid of reactors. The neutron-leakage-compensation method is taken in the measuring mechanism. In the primary measuring configuration, the mini-boron-water annulus and two-channel and central calibration loop are adopted. The calibration ring and constant-temperature of boron-water can be remotely controlled by secondary instruments. With the microcomputer data processing system the boron concentration is automatically measured and calibrated in on-line mode. The meter has many advantages such as high accuracy, fast response, multi-applications, high reliability and convenience

  8. Magnetostriction of the polycrystalline Fe80Al20 alloy doped with boron

    International Nuclear Information System (INIS)

    Bormio-Nunes, Cristina; Teodoro dos Santos, Claudio; Botani de Souza Dias, Mateus; Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael

    2012-01-01

    Highlights: ► Fe 80 Al 20 polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. ► B stabilizes α-FeAl phase and a coexistence of α-FeAl + Fe 3 Al improves magnetostriction. ► Presence of Fe 2 B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe 80 Al 20 polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic α-FeAl and/or Fe 3 Al and Fe 2 B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of α-FeAl and a correspondent decrease of the Fe 3 Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe 2 B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe 80 Al 20 alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the α-FeAl and Fe 3 Al phases could be reached.

  9. The All Boron Carbide Diode Neutron Detector: Experiment and Modeling Approach

    International Nuclear Information System (INIS)

    Sabirianov, Ildar F.; Brand, Jennifer I.; Fairchild, Robert W.

    2008-01-01

    Boron carbide diode detectors, fabricated from two different polytypes of semiconducting boron carbide, will detect neutrons in reasonable agreement with theoretical expectations. The performance of the all boron carbide neutron detector differs, as expected, from devices where a boron rich neutron capture layer is distinct from the diode charge collection region (i.e. a conversion layer solid state detector). Diodes were fabricated from natural abundance boron (20% 10 B and 80% 11 B.) directly on the metal substrates and metal contacts applied to the films as grown. The total boron depth was on the order of 2 microns. This is clearly not a conversion-layer configuration. The diodes were exposed to thermal neutrons generated from a paraffin moderated plutonium-beryllium source in moderated and un-moderated, as well as shielded and unshielded experimental configurations, where the expected energy peaks at at 2.31 MeV and 2.8 MeV were clearly observed, albeit with some incomplete charge collection typical of thinner diode structures. The results are compared with other boron based thin film detectors and literature models. (authors)

  10. 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

  11. High-performance liquid chromatographic method to evaluate the hydrogen atom transfer during reaction between 1,1-diphenyl-2-picryl-hydrazyl radical and antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Boudier, Ariane; Tournebize, Juliana [CITHEFOR - EA 3452, Faculte de Pharmacie, Nancy-Universite, 5 Rue Albert Lebrun, BP 80403, 54001 Nancy Cedex (France); Bartosz, Grzegorz [Department of Molecular Biophysics, University of Lodz, Lodz (Poland); El Hani, Safae; Bengueddour, Rachid [Laboratoire de Nutrition et Sante, Biology Department, Faculty of Sciences, Ibn Tofail University, Kenitra (Morocco); Sapin-Minet, Anne [CITHEFOR - EA 3452, Faculte de Pharmacie, Nancy-Universite, 5 Rue Albert Lebrun, BP 80403, 54001 Nancy Cedex (France); Leroy, Pierre, E-mail: pierre.leroy@pharma.uhp-nancy.fr [CITHEFOR - EA 3452, Faculte de Pharmacie, Nancy-Universite, 5 Rue Albert Lebrun, BP 80403, 54001 Nancy Cedex (France)

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer Both 1,1-diphenyl-2-picrylhydrazyl radical and its product measurement by HPLC. Black-Right-Pointing-Pointer Lowest limit of detection by monitoring 1,1-diphenyl-2-picryl-hydrazine. Black-Right-Pointing-Pointer Adsorption problem of the radical on HPLC parts have been pointed out. - Abstract: 1,1-Diphenyl-2-picrylhydrazyl (DPPH{center_dot}) is a stable nitrogen centred radical widely used to evaluate direct radical scavenging properties of various synthetic or natural antioxidants (AOs). The bleaching rate of DPPH{center_dot} absorbance at 515 nm is usually monitored for this purpose. In order to avoid the interference of complex coloured natural products used as antioxidant supplements or cosmetics, HPLC systems have been reported as alternative techniques to spectrophotometry. They also rely upon measurement of DPPH{center_dot} quenching rate and none of them permits to identify and measure 1,1-diphenyl-2-picryl-hydrazine (DPPH-H), the reduced product of DPPH{center_dot} resulting from hydrogen atom transfer (HAT), which is the main mechanism of the reaction between DPPH{center_dot} and AOs. We presently report an HPLC method devoted to the simultaneous measurement of DPPH{center_dot} and DPPH-H. Both were fully separated on a C18 column eluted with acetonitrile-10 mM ammonium citrate buffer pH 6.8 (70:30, v/v) and detected at 330 nm. Adsorption process of DPPH{center_dot} onto materials of the HPLC system was pointed out. Consequently, the linearity range observed for DPPH{center_dot} was restricted, thus a much lower limit of detection was obtained for DPPH-H than for DPPH{center_dot} using standards (0.02 and 14 {mu}M, respectively). The method was applied to three commonly used AOs, i.e. Trolox{sup Registered-Sign }, ascorbic acid and GSH, and compared with spectrophotometry. Further application to complex matrices (cell culture media, vegetal extracts) and nanomaterials demonstrated (i) its usefulness because of

  12. 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 ...

  13. Effects of boron on experimental dental caries activity

    Energy Technology Data Exchange (ETDEWEB)

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

    1974-01-01

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

  14. Biological effects of accelerated boron, carbon, and neon ions

    International Nuclear Information System (INIS)

    Grigoryev, Yu.G.; Ryzhov, N.I.; Popov, V.I.

    1975-01-01

    The biological effects of accelerated boron, carbon, and neon ions on various biological materials were determined. The accelerated ions included 10 B, 11 B, 12 C, 20 Ne, 22 Ne, and 40 Ar. Gamma radiation and x radiation were used as references in the experiments. Among the biological materials used were mammalian cells and tissues, yeasts, unicellular algae (chlorella), and hydrogen bacteria. The results of the investigation are given and the biophysical aspects of the problem are discussed

  15. Preparation, Characterization and Adsorption Study of Granular Activated Carbon/Iron oxide composite for the Removal of Boron and Organics from Wastewater

    Directory of Open Access Journals (Sweden)

    Affam Augustine Chioma

    2018-01-01

    Full Text Available Boron and organics maybe in high concentration during production of oil and gas, fertilizers, glass, and detergents. In addition, boron added to these industrial processes may require to be removed by the wastewater treatment plant. The preparation, characterization and application of iron oxide-activated carbon composite for removal of boron and COD was studied. The one variable at a time (OVAT method was implemented to obtain desirable operating conditions (adsorbent dosage 5 g/L, reaction time 2 h, agitation speed 100 rpm, pH 5 for COD removal and pH 9 for boron removal. It was found that boron and organics present in a sample wastewater may require to be treated separately to remove the contaminants. The study achieved 97 and 70% for boron and COD removal, respectively. Adsorption as an alternative cheap source of treatment and its practicability for small communities is recommended as effective in removal of contaminants from river water.

  16. Preparation, Characterization and Adsorption Study of Granular Activated Carbon/Iron oxide composite for the Removal of Boron and Organics from Wastewater

    Science.gov (United States)

    Chioma Affam, Augustine; Chung Wong, Chee; Seyam, Mohammed A. B.; Matt, Chelsea Ann Anak Frederick; Lantan Anak Sumbai, Josephine; Evuti, Abdullahi Mohammed

    2018-03-01

    Boron and organics maybe in high concentration during production of oil and gas, fertilizers, glass, and detergents. In addition, boron added to these industrial processes may require to be removed by the wastewater treatment plant. The preparation, characterization and application of iron oxide-activated carbon composite for removal of boron and COD was studied. The one variable at a time (OVAT) method was implemented to obtain desirable operating conditions (adsorbent dosage 5 g/L, reaction time 2 h, agitation speed 100 rpm, pH 5 for COD removal and pH 9 for boron removal). It was found that boron and organics present in a sample wastewater may require to be treated separately to remove the contaminants. The study achieved 97 and 70% for boron and COD removal, respectively. Adsorption as an alternative cheap source of treatment and its practicability for small communities is recommended as effective in removal of contaminants from river water.

  17. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

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

  18. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

  19. A DMS kinetic study of the boron oxides vapor in the combustion front of SHS system Mo + B

    International Nuclear Information System (INIS)

    Kashireninov, O.E.; Yuranov, I.A.

    1994-01-01

    The distribution of the boron oxides vapor in the combustion wave of the SHS system Mo + B has been studied by the dynamic mass spectrometry technique (DMS) to test the thermodynamically based hypothesis for the key role of gas-phase transport in solid-state combustion. The molecular beam sampling of the gases over the burning tablet was performed by a stationary probe cone from the moving combustion wave. Ion currents of boron oxides were recorded at 10--20 ms intervals that afforded spatial resolution of 0.1--0.2 mm. It has been found that the distribution of the boron oxides vapor pressure along the combustion wave corresponds to the known zones of preheating, reaction, and postcombustion. The rapid increase of B 2 O 2 pressure takes place in the preheating zone as a result of the reaction B(s) + B 2 O 3 (g) = B 2 O 2 (g). Boron oxides are not observed over the reaction zone because of their complete decay in the reaction with Mo(s) to form molybdenum boride(s). The appearance The appearance of boron oxide vapors over the postcombustion zone is due to the evaporation of B 2 O 3 (l). The effective kinetic parameters are estimated from the data obtained. The results show that solid-state combustion of the Mo + B system proceeds predominantly through formation of gas-phase boron oxides

  20. Defects in boron carbide: First-principles calculations and CALPHAD modeling

    International Nuclear Information System (INIS)

    Saengdeejing, Arkapol; Saal, James E.; Manga, Venkateswara Rao; Liu Zikui

    2012-01-01

    The energetics of defects in B 4+x C boron carbide and β-boron are studied through first-principles calculations, the supercell phonon approach and the Debye–Grüneisen model. It is found that suitable sublattice models for β-boron and B 4+x C are B 101 (B,C) 4 and B 11 (B,C) (B,C,Va) (B,Va) (B,C,Va), respectively. The thermodynamic properties of B 4+x C, β-boron, liquid and graphite are modeled using the CALPHAD approach based on the thermochemical data from first-principles calculations and experimental phase equilibrium data in the literature. The concentrations of various defects are then predicted as a function of carbon composition and temperature.

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

    Czech Academy of Sciences Publication Activity Database

    Šopík, Břetislav

    2009-01-01

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

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

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Søtofte, Inger

    2002-01-01

    In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report the synthe......In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report...... the synthesis of the compounds and our investigations on glucose complexation as studied by C-13 NMR spectroscopy. The crystal structure of 2,4,6-tris[2-(N-ferrocenylmethyl-N-methylaminomethyl) phenyl] boroxin (13) (boroxin of boronic acid 3) (boroxin = cyclotriboroxane) was obtained and compared...... with structures obtained of 2,4,6-tris[2-(N,N-dimethylaminomethyl)phenyl]boroxin (14) and 2,2-dimethyl-1,3-diyl[2-(N,N-dimethylaminomethyl)phenyl]boronate (15). The structure of 13 shows the existence of intramolecular B-N bonds in the solid phase....

  3. Evaluation of selective boron absorption in liver tumors

    International Nuclear Information System (INIS)

    Chiaraviglio, D.; Grazia, F. De; Zonta, A.; Altieri, S.; Pedroni, P.; Braghieri, B.; Fossati, F.; Pinelli, T.; Perotti, A.; Specchiarello, S.; Perlini, G.; Rief, H.

    1988-01-01

    The first step was a pharmacokinetic study to identify substances which are good boron transporters and are therefore able to provide a high concentration of the nuclide with respect to the healthy hepatic tissue in the MHN. For this purpose the tumor M5076/73 (M5), which matastasizes spontaneously in liver, was inoculated subcutaneously in a group of C57B1/6 mice. Thirty days after the inoculation, when 90% of the liver was invaded by metastases, a boric acid 0.3 M solution enriched to 96% 10 B was injected into the caudal vein. The mice were sacrificed and the liver was frozen for measurements. Boron concentration in the various samples was achieved by measuring the energy distribution of α particles produced in the nuclear reaction 10 B(n, α) 7 Li induced by a thermal neutron beam extracted from the Triga Mark II reactor,

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

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

    CERN Document Server

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

    2010-01-01

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

  6. Determination of soluble carbon in nuclear grade boron carbide

    International Nuclear Information System (INIS)

    Vega Bustillos, J.O.; Gomes, R.; Camaro, J.; Zorzetto, F.; Domingues, P.; Riella, H.

    1990-05-01

    The present work describes two different techniques (manometric and wet chemical) for the soluble carbon determination in nuclear grade boron carbide. The techniques are based on the reaction of the boron carbide with a sulfocromic mixture, generating CO 2 . The techniques differ on the mode they do the measurement of CO 2 produced. By wet chemical technique the CO 2 is absorved in a barium hydroxide solution and is determinated by titration. In the manometric technique the CO 2 gas is measured using a McLeod gauge. The gas produced by the latter technique is analysed by mass spectrometry. The details of the analytical technique and the data obtained are discussed. (author) [pt

  7. Two-dimensional analysis of three-body reactions 11B(p,αα) from 163 keV to MeV

    International Nuclear Information System (INIS)

    Engelhardt, D.; Fontenille, J.

    1967-01-01

    An experimental apparatus for two-dimensions analysis of the break-up of 12 C * produced by the reaction 11 B(p,αα) 4 He, at proton bombarding energies between 163 keV and 2 MeV, is described. It uses Si surface barrier detectors and, fast-slow coincidence techniques: the energy resolution is about 40 keV and time resolution 6 ns. A 4096 channel analyser and a small digital computer was used for information storage and data processing. The experimental set-up was tested on the C.E.N.G. 2 MeV Van de Graaff accelerator. The spectra of the 12 C * decay products taken at proton bombarding energies of 163 keV and 680 keV at different angles between the two α-counters are shown. They indicate strong evidence for sequential decay of 12 C * to the 8 Be fundamental, first or second excited level. (authors) [fr

  8. Improvement of wheat yield grown under drought stress by boron foliar application at different growth stages

    Directory of Open Access Journals (Sweden)

    F.M.F. Abdel-Motagally

    2018-04-01

    Full Text Available Two field experiments were conducted to determine the effect of boron foliar application and water stress on yield of wheat plant grown in calcareous soil during 2013/2014 and 2014/2015 seasons. The highest mean values obtained against boron application time were potential contributor to total grains mass by improving the plant height (99.42 and 98.32 cm, spike length (11.86 and 11.72 cm, number of spikelets m−2 (332.65 and 324.35, grain yield plant−1 (21.56 and 20.26 g, 1000-grain weight (35.2 and 37.4 g and grain yield (1.87 and 1.85 ton fed.−1, which were recorded at normal irrigation level (100% from the amount of water consumption for wheat with boron spraying at booting stage (B1 in the first and second seasons, respectively. Furthermore, boron application significantly enhanced all studied growth traits under water stress levels (50% from the amount of water consumption for wheat compared to B-untreated plants. Boron spraying at booting stage enhances also plant pigments contents recording its highest mean values under normal water level (100% from the amount of water consumption for wheat. The reduction in stress markers (proline and H2O2 and the enhancement of plant pigments content under water stress levels (50% from the amount of water consumption for wheat by B spraying suggests an alleviating effect of boron foliar application to water stress in the test plant. This alleviating effect was more pronounced when B applied at booting stage. Therefore, booting stage was found to be the best time for boron application to get higher grains production and consequently, better economic returns of wheat. Keywords: Wheat, Growth stages, Boron application time, Water stress, Crop yield, Plant pigments, Proline, H2O2

  9. Determination of Boron in soils and plants samples using spectrophotometric method

    International Nuclear Information System (INIS)

    Stas, J.; Hariri, Z.

    2011-10-01

    In this work, the concentration of boron in soil and plant samples was determined with UV-vis spectrophotometer by using azomethine-H as a complex reagent. The calibration curve for boron determination in the range of (0μ3 g.mL - 1) was constructed by plotting the measured absorption of the yellow azomethine-H-B complex at λmax = 412.6 nm against boron concentration in the aqueous phase. The detection limit, repeatability limit, intermediate precision, accuracy, and recovery coefficient of this method were calculated and found to be 0.021 μg.mL - 1, 0.335% , 0.81%, 2.93%, (98.4-101.5)% respectively. The influence of some foreign ions on the determination of boron were also investigated in detail, most of the studied ions, like iron, iodide, and calcium can be tolerated within the ranges of (20-35μg.mL-1), (3000-5000μg.mL - 1) , (15000-30000μg.mL - 1) respectively. This is due to the fact, that ascorbic acid and EDTA in the buffer masking reagent reaction system can be very effective in masking these ions. This method was found to be economic and suitable for boron determination in standard and local samples (soil, plant) and requires small amount of sample (1g). This method can also be applied for boron determination in water samples (drinking and industrial waste water).(author)

  10. Detection of boron in metal alloys with solid state nuclear track detector by neutron induced autoradiography

    International Nuclear Information System (INIS)

    Ali Nabipour; Hosseini, A.; Afarideh, H.

    2002-01-01

    Neutron induced autoradiography is very useful technique for detection as well as measurement of Boron densities in metal alloys. The method is relatively simple and quite sensitive in comparison with other techniques with resolution in the range of PPM. Using this technique with it is also possible to investigate microscopic scattering of Boron in metal alloys. In comparison with most techniques neutron induced autoradiography has its own difficulties and limitations. In this research measurement of Boron densities and investigation of that diffusion in metal alloys has been carried out. A flat nicely polished Boron doped metal samples is covered with a track detecting plastic (CR-39 solid state nuclear track detector) and exposed to thermal neutron dose. After irradiation the plastic detector have been removed and put in an etching solution. Since the diffusion rate of corrosive solution in those area, which heavy ions have been, produces as the result of nuclear reaction with thermal neutron are more than the other areas, some cavities are formed. The diameter of cavities or tracks cross section are increased with increasing the etching time, to some extent that it is possible to observe the cavities with optical microscopes. The density of tracks on the detector surface is directly related to the Boron concentration in the sample and thermal neutron dose. So by measuring the number of tracks on surface of the detector it would possible to calculate the concentration of Boron in metal samples. (Author)

  11. Removal of boron(III) by N-methylglucamine-type cellulose derivatives with higher adsorption rate

    International Nuclear Information System (INIS)

    Inukai, Yoshinari; Tanaka, Yoshiharu; Matsuda, Toshio; Mihara, Nobutake; Yamada, Kouji; Nambu, Nobuyoshi; Itoh, Osamu; Doi, Takao; Kaida, Yasuhiko; Yasuda, Seiji

    2004-01-01

    To obtain adsorbents for boron(III) derived from a natural polymer, two forms (powder and fiber) of N-methylglucamine-type cellulose derivatives were newly synthesized. After the graft polymerization of two forms of cellulose with vinyl monomer having epoxy groups, the N-methylglucamine-type cellulose derivatives were obtained by the reaction of the grafted cellulose with N-methylglucamine. The adsorption capacities of the cellulose derivatives for boron(III) were the same levels as that of a commercially available N-methylglucamine-type polystyrene resin. However, the cellulose derivatives adsorbed boron(III) more quickly than the polystyrene resin. The adsorption and desorption of boron(III) with a column method using the cellulose fiber were achieved at a higher flow rate than that using the polystyrene resin. In addition, the boron(III), adsorbed on the cellulose fiber column, was quantitatively recovered with dilute hydrochloric acid in 20- and 200-fold increased concentrations. Consequently, it was found that the cellulose derivatives were superior to the polystyrene resin as adsorbents for boron(III) for treatment of a large quantity of wastewater

  12. Determination of boron in waters by using methyl borate generation and flame atomic-emission spectrometry

    International Nuclear Information System (INIS)

    Castillo, J.R.; Mir, J.M.; Martinez, C.; Bendicho, C.

    1985-01-01

    An improved method is proposed for the determination of boron in waters. The esterification reaction between boric acid and methanol in a concentrated sulphuric acid medium and the vaporisation of the methyl borate formed (boiling-point, 68 C) are used in the determination by boron by measuring the emission of the BO 2 radical at 548 nm. This reaction is carried out in a simple and inexpensive generator, designed for this purpose, and the heat developed in it causes the rapid volatilisation of the methyl borate. Thus no collection systems or carrier gas are required. The proposed method gives an improved detection limit and it can be applied to the determination of boron in water samples. It is both rapid and highly selective. (author)

  13. A study on the prevalence of dog erythrocyte antigen 1.1 and detection of canine Babesia by polymerase chain reaction from apparently healthy dogs in a selected rural community in Zimbabwe

    Directory of Open Access Journals (Sweden)

    Solomon Dhliwayo

    2016-10-01

    Full Text Available A study was carried out to determine the prevalence of blood group antigen dog erythrocyte antigen (DEA 1.1 in mixed breed dogs in rural Chinamhora, Zimbabwe. DEA 1.1 is clinically the most important canine blood group as it is the most antigenic blood type; hence, DEA 1.1 antibodies are capable of causing acute haemolytic, potentially life-threatening transfusion reactions. In this study, blood samples were collected from 100 dogs in Chinamhora, and blood typing was carried out using standardised DEA 1.1 typing strips with monoclonal anti–DEA 1.1 antibodies (Alvedia® LAB DEA 1.1 test kits. Polymerase chain reaction for detecting Babesia spp. antigen was carried out on 58 of the samples. Of the 100 dogs, 78% were DEA 1.1 positive and 22% were DEA 1.1 negative. A significantly (p = 0.02 higher proportion of females (90.5% were DEA 1.1 positive than males (69.0%. The probability of sensitisation of recipient dogs following first-time transfusion of untyped or unmatched blood was 17.2%, and an approximately 3% (2.95% probability of an acute haemolytic reaction following a second incompatible transfusion was found. Babesia spp. antigen was found in 6.9% of the samples. No significant relationship (χ2 = 0.56, p = 0.45 was found between DEA 1.1 positivity and Babesia spp. antigen presence. Despite a low probability of haemolysis after a second incompatibility transfusion, the risk remains present and should not be ignored. Hence, where possible, blood typing for DEA 1.1 is recommended. A survey of DEA 3, 4, 5 and 7 in various breeds is also recommended.

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

    International Nuclear Information System (INIS)

    Garabalino, Marcela A.; Monti Hughes, Andrea; Molinari, Ana J.; Heber, Elisa M.; Pozzi, Emiliano C.C.; Itoiz, Maria E.; Trivillin, Veronica A.; Schwint, Amanda E.; Nievas, Susana; Aromando, Romina F.

    2009-01-01

    Boron Neutron Capture Therapy (BNCT) is a binary treatment modality that involves the selective accumulation of 10 B carriers in tumors followed by irradiation with thermal or epithermal neutrons. The high linear energy transfer alpha particles and recoiling 7 Li nuclei emitted during the capture of a thermal neutron by a 10 B nucleus have a short range and a high biological effectiveness. Thus, BNCT would potentially target neoplastic tissue selectively. In previous studies we demonstrated the therapeutic efficacy of different BNCT protocols in an experimental model of oral cancer. More recently we performed experimental studies in normal rat liver that evidenced the feasibility of treating liver metastases employing a novel BNCT protocol proposed by JEC based on ex-situ treatment and partial liver auto-transplant. The aim of the present study was to perform biodistribution studies with different boron compounds and different administration protocols to determine the protocols that would be therapeutically useful in 'in vivo' BNCT studies at the RA-3 Nuclear Reactor in an experimental model of liver metastases in rats. Materials and Methods. A total of 70 BDIX rats (Charles River Lab., MA, USA) were inoculated in the liver with syngeneic colon cancer cells DH/DK12/TRb (ECACC, UK) to induce the development of subcapsular metastatic nodules. 15 days post-inoculation the animals were used for biodistribution studies. A total of 11 protocols were evaluated employing the boron compounds boronophenylalanine (BPA) and GB-10 (Na 2 10 B 1 -0H 10 ), alone or combined employing different doses and administration routes. Tumor, normal tissue and blood samples were processed for boron measurement by ICP-OES. Results. Several protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue, i.e. BPA 15.5 mg 10 B/kg iv + GB-10 50 mg 10 B/kg iv; BPA 46.5 mg 10 B/kg ip; BPA 46.5 mg 10 B/kg ip

  15. Polyvinylpolypyrrolidone-Supported Boron Trifluoride; Highly Efficient Catalyst for the Synthesis of N-tert-Butyl Amides

    Directory of Open Access Journals (Sweden)

    Masoud Mokhtary

    2012-01-01

    Full Text Available Highly efficient method for the preparation of N-tert-butyl amides by reaction of nitriles with tert-butyl acetate is described using polyvinylpolypyrrolidone-supported boron trifluoride (PVPP-BF3 at 70°C in good to excellent yields. Selective amidation of benzonitrile in the presence of acetonitrile was also achieved. polyvinylpolypyrrolidone-boron trifluoride complex shows non-corrosive and stable solid catalyst elevated Lewis acid property.

  16. Dosimetry and stability studies of the boron neutron capture therapy agent F-BPA-Fr using PET and MRI

    Science.gov (United States)

    Dyke, Jonathan Paul

    The treatment of deep seated brain tumors such as glioblastoma Multiforme has been unsuccessful for many patients. Surgical debulking, chemotherapy and standard radiotherapy have met with limited success. Boron neutron capture therapy offers a binary mode brachytherapy based on the following capture reaction that may provide an innovative alternative to standard forms of treatment:10B + n /to/ 11B /to 7Li + 4He + 2.31 MeVBoron is chemically attached to a tumor binding compound creating a non-toxic neutron absorber. A dose of epithermal neutrons provides the catalyst to produce the lithium and alpha particles which destroy any tissue within a length of one cell diameter from the boron compound. This dissertation uses 19F-MRI and 18F-PET to provide answers to the localization and biodistribution questions that arise in such a treatment modality. Practical patient dosimetry and actual treatment planning using the PET data is also examined. Finally, theoretical work done in the areas of compartmental modelling dealing with pharmacokinetic uptake of the PET radiotracer and dose analysis in microdosimetry is also presented.

  17. Primary Coolant pH Control for Soluble Boron-Free PWRs

    International Nuclear Information System (INIS)

    Cheon, Yang Ho; Lee, Nam Yeong; Park, Byeong Ho; Park, Seong Chan; Kim, Eun Kee

    2015-01-01

    These should be considered when evaluating and designing the operating pH program for nuclear power plants. This paper discusses the advanced water chemistry strategies to keep pace with the recent global trends related to pH control in the primary water system for soluble boron pressurized water reactor (PWR) plants. Finally, the objective of this work is to study primary coolant pH control for soluble boron-free PWR plants. This paper reviewed the advanced water chemistry strategies to keep pace with the recent global trends related to pH control in the primary water chemistry system for soluble boron PWR plants. The new chemistry trend for the primary coolant is towards adaption of the constant and elevated chemistry. Finally, this work studied primary coolant pH control for soluble boron-free PWR plants. The ammonia-based water chemistry related to pH control for boron-free PWR plants was discussed. The ammonia-based water chemistry is not recommended to avoid fluctuation of the pH value by ammonia radiolysis and to reduce C-14 production in reactor coolant from reaction with dissolved nitrogen. Also, the potassium-based water chemistry related to pH control for boron-free PWR plants was discussed. KOH has a potential as an alternative pH control agent for soluble boron-free PWR plants. The potassium-based water chemistry related to pH control is recommended for boron-free operation as follows

  18. Helium diffusion in irradiated boron carbide

    International Nuclear Information System (INIS)

    Hollenberg, G.W.

    1981-03-01

    Boron carbide has been internationally adopted as the neutron absorber material in the control and safety rods of large fast breeder reactors. Its relatively large neutron capture cross section at high neutron energies provides sufficient reactivity worth with a minimum of core space. In addition, the commercial availability of boron carbide makes it attractive from a fabrication standpoint. Instrumented irradiation experiments in EBR-II have provided continuous helium release data on boron carbide at a variety of operating temperatures. Although some microstructural and compositional variations were examined in these experiments most of the boron carbide was prototypic of that used in the Fast Flux Test Facility. The density of the boron carbide pellets was approximately 92% of theoretical. The boron carbide pellets were approximately 1.0 cm in diameter and possessed average grain sizes that varied from 8 to 30 μm. Pellet centerline temperatures were continually measured during the irradiation experiments

  19. Boron thermal/epithermal neutron capture therapy

    International Nuclear Information System (INIS)

    Fairchild, R.G.

    1982-01-01

    The development of various particle beams for radiotherapy represents an attempt to improve dose distribution, and to provide high LET radiations which are less sensitive to ambient physical and radiobiological factors such as oxygen tension, cell cycle, and dose rate. In general, a compromise is necessary as effective RBE is reduced in order to spread the dose distribution over the anticipated tumor volume. The approach of delivering stable non-toxic isotopes to tumor, and then activating these atoms subsequently via an external radiation beam has mator advantages; problems associated with high uptake of these isotopes in competing cell pools are obviated, and the general tumor volume can be included in the treatment field of the activating beam. As long as the normal tissues supporting tumor show a low uptake of the isotope to be activated, and as long as the range of the reaction products is short, dose will be restricted to tumor, with a consequent high therapeutic ratio. Neutron Capture Therapy (NCT) is generally carried out by activating boron-10 with low energy neutrons. The range of the high LET, low OER particles from the 10 B(n, α) 7 Li reaction is approx. 10μ, or one cell diameter, a situation that is optimal for cell killing. Significant advantages may be gained by using the NCT procedure in conjunction with improved tissue penetration provided with epithermal or filtered beams, and new compounds showing physiological binding to tumor

  20. Prompt gamma ray diagnostics and enhanced hadron-therapy using neutron-free nuclear reactions

    Science.gov (United States)

    Giuffrida, L.; Margarone, D.; Cirrone, G. A. P.; Picciotto, A.; Cuttone, G.; Korn, G.

    2016-10-01

    We propose a series of simulations about the potential use of Boron isotopes to trigger neutron-free (aneutronic) nuclear reactions in cancer cells through the interaction with an incoming energetic proton beam, thus resulting in the emission of characteristic prompt gamma radiation (429 keV, 718 keV and 1435 keV). Furthermore assuming that the Boron isotopes are absorbed in cancer cells, the three alpha-particles produced in each p-11B aneutronic nuclear fusion reactions can potentially result in the enhancement of the biological dose absorbed in the tumor region since these multi-MeV alpha-particles are stopped inside the single cancer cell, thus allowing to spare the surrounding tissues. Although a similar approach based on the use of 11B nuclei has been proposed in [Yoon et al. Applied Physics Letters 105, 223507 (2014)], our work demonstrate, using Monte Carlo simulations, the crucial importance of the use of 10B nuclei (in a solution containing also 11B) for the generation of prompt gamma-rays, which can be applied to medical imaging. In fact, we demonstrate that the use of 10B nuclei can enhance the intensity of the 718 keV gamma-ray peak more than 30 times compared to the solution containing only 11B nuclei. A detailed explanation of the origin of the different prompt gamma-rays, as well as of their application as real-time diagnostics during a potential cancer treatment, is here discussed.

  1. Recombination methods for boron neutron capture therapy dosimetry

    International Nuclear Information System (INIS)

    Golnik, N.; Tulik, P.; Zielczynski, M.

    2003-01-01

    The radiation effects of boron neutron capture therapy (BNCT) are associated with four-dose-compartment radiation field - boron dose (from 10 B(n,α) 7 Li) reaction), proton dose from 14 N(n,p) 14 C reaction, neutron dose (mainly fast and epithermal neutrons) and gamma-ray dose (external and from capture reaction 1 H(n,γ) 2 D). Because of this the relation between the absorbed dose and the biological effects is very complex and all the above mentioned absorbed dose components should be determined. From this point of view, the recombination chambers can be very useful instruments for characterization of the BNCT beams. They can be used for determination of gamma and high-LET dose components for the characterization of radiation quality of mixed radiation fields by recombination microdosimetric method (RMM). In present work, a graphite high-pressure recombination chamber filled with nitrogen, 10 BF 3 and tissue equivalent gas was used for studies on application of RMM for BNCT dosimetry. The use of these gases or their mixtures opens a possibility to design a recombination chamber for determination of the dose fractions due to gamma radiation, fast neutrons, neutron capture on nitrogen and high LET particles from (n, 10 B) reaction in simulated tissue with different content of 10 B. (author)

  2. Medical aspects of boron-slow neutron capture therapy

    International Nuclear Information System (INIS)

    Sweet, W.H.

    1986-01-01

    Earlier radiations of patients with cerebral tumors disclosed the need: (1) to find a carrier of the boron compound which would leave the blood and concentrate in the tumor, (2) to use a more penetrating neutron beam, and (3) to develop a much faster method for assaying boron in blood and tissue. To some extent number1 has been accomplished in the form of Na 2 B 12 H 11 SH, number2 has yet to be achieved, and number3 has been solved by the measurement of the 478-keV gamma ray when the 10 B atom disintegrates following its capture of a slow neutron. The hitherto unreported data in this paper describe through the courtesy of Professor Hiroshi Hatanaka his studies on the pharmacokinetics and quality control of Na 2 B 12 H 11 SH based on 96 boron infusions in 86 patients. Simultaneous blood and tumor data are plotted here for 30 patients with glioblastomas (Grade III-IV gliomas), illustrating remarkable variability. Detailed autopsy findings on 18 patients with BNCT showed radiation injury in only 1. Clinical results in 12 of the most favorably situated glioblastomas reveal that 5 are still alive with a 5-year survival rate of 58% and the excellent Karnofsky performance rating of 87%. For the first time evidence is presented that slow-growing astrocytomas may benefit from BNCT. 10 references, 8 figures, 5 tables

  3. Synthesis of 9H-indeno [1, 2-b] pyrazine and 11H-indeno [1, 2-b] quinoxaline derivatives in one-step reaction from 2-bromo-4-chloro-1-indanone

    OpenAIRE

    Jasouri, S.; Khalafy, J.; Badali, M.; Prager, R.H.

    2011-01-01

    The reaction of 2-bromo-4-chloro-1-indanone with 2,3-diaminomaleonitrile, benzene-1,2-diamine and 4-methylbenzene-1,2-diamine in glacial acetic acid gave 8-chloro-9H-indeno[1,2-b]pyrazine-2,3-dicarbonitrile, 1-chloro-11H-indeno[1,2-b]quinoxa-line and 1-chloro-7-methyl-11H-indeno[1,2-b]quinoxaline, respectively, in good yield.

  4. Primary system boron dilution analysis

    International Nuclear Information System (INIS)

    Crump, R.J.; Naretto, C.J.; Borgen, R.A.; Rockhold, H.C.

    1978-01-01

    The results are presented for an analysis conducted to determine the potential paths through which nonborated water or water with insufficient boron concentration might enter the LOFT primary coolant piping system or reactor vessel to cause dilution of the borated primary coolant water. No attempt was made in the course of this analysis to identify possible design modifications nor to suggest changes in administrative procedures or controls

  5. Spectroscopic investigation and computational analysis of charge transfer hydrogen bonded reaction between 3-aminoquinoline with chloranilic acid in 1:1 stoichiometric ratio

    Science.gov (United States)

    Al-Ahmary, Khairia M.; Alenezi, Maha S.; Habeeb, Moustafa M.

    2015-10-01

    Charge transfer hydrogen bonded reaction between the electron donor (proton acceptor) 3-aminoquinoline with the electron acceptor (proton donor) chloranilic acid (H2CA) has been investigated experimentally and theoretically. The experimental work included the application of UV-vis spectroscopy to identify the charge transfer band of the formed complex, its molecular composition as well as estimating its formation constants in different solvent included acetonitrile (AN), methanol (MeOH), ethanol (EtOH) and chloroform (CHL). It has been recorded the presence of new absorption bands in the range 500-550 nm attributing to the formed complex. The molecular composition of the HBCT complex was found to be 1:1 (donor:acceptor) in all studied solvents based on continuous variation and photometric titration methods. In addition, the calculated formation constants from Benesi-Hildebrand equation recorded high values, especially in chloroform referring to the formation of stable HBCT complex. Infrared spectroscopy has been applied for the solid complex where formation of charge and proton transfer was proven in it. Moreover, 1H and 13C NMR spectroscopies were used to characterize the formed complex where charge and proton transfers were reconfirmed. Computational analysis included the use of GAMESS computations as a package of ChemBio3D Ultr12 program were applied for energy minimization and estimation of the stabilization energy for the produced complex. Also, geometrical parameters (bond lengths and bond angles) of the formed HBCT complex were computed and analyzed. Furthermore, Mullikan atomic charges, molecular potential energy surface, HOMO and LUMO molecular orbitals as well as assignment of the electronic spectra of the formed complex were presented. A full agreement between experimental and computational analysis has been found especially in the existence of the charge and proton transfers and the assignment of HOMO and LUMO molecular orbitals in the formed complex as

  6. Computer modeling the boron compound factor in normal brain tissue

    International Nuclear Information System (INIS)

    Gavin, P.R.; Huiskamp, R.; Wheeler, F.J.; Griebenow, M.L.

    1993-01-01

    The macroscopic distribution of borocaptate sodium (Na 2 B 12 H 11 SH or BSH) in normal tissues has been determined and can be accurately predicted from the blood concentration. The compound para-borono-phenylalanine (p-BPA) has also been studied in dogs and normal tissue distribution has been determined. The total physical dose required to reach a biological isoeffect appears to increase directly as the proportion of boron capture dose increases. This effect, together with knowledge of the macrodistribution, led to estimates of the influence of the microdistribution of the BSH compound. This paper reports a computer model that was used to predict the compound factor for BSH and p-BPA and, hence, the equivalent radiation in normal tissues. The compound factor would need to be calculated for other compounds with different distributions. This information is needed to design appropriate normal tissue tolerance studies for different organ systems and/or different boron compounds

  7. Boron removal from geothermal waters by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-01

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

  8. Boron removal from geothermal waters by electrocoagulation

    International Nuclear Information System (INIS)

    Yilmaz, A. Erdem; Boncukcuoglu, Recep; Kocakerim, M. Muhtar; Yilmaz, M. Tolga; Paluluoglu, Cihan

    2008-01-01

    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%

  9. Boron-doped MnO{sub 2}/carbon fiber composite electrode for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Hong Zhong, E-mail: hzchi@hdu.edu.cn [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhu, Hongjie [College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Gao, Linhui [Center of Materials Engineering, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2015-10-05

    Highlights: • Interstitial ion in MnO{sub 2} lattice. • Porous film composed by interlocking worm-like nanostructure. • Boron-doped birnessite-type MnO{sub 2}/carbon fiber composite electrode. • Enhanced capacitive properties through nonmetal element doping. - Abstract: The boron-doped MnO{sub 2}/carbon fiber composite electrode has been prepared via in situ redox reaction between potassium permanganate and carbon fibers in the presence of boric acid. The addition of boron as dopant results in the increase of growth-rate of MnO{sub 2} crystal and the formation of worm-like nanostructure. Based on the analysis of binding energy, element boron incorporates into the MnO{sub 2} lattice through interstitial mode. The doped electrode with porous framework is beneficial to pseudocapacitive reaction and surface charge storage, leading to higher specific capacitance and superior rate capability. After experienced 1000 cycles, the boron-doped MnO{sub 2} still retain a higher specific capacitance by about 80% of its initial value. The fall in capacitance is blamed to be the combination of the formation of soluble Mn{sup 2+} and the absence of active site on the outer surface.

  10. Radio response of human lymphocytes pretreated with boron and gadoliniums assessed by the, comet assay

    International Nuclear Information System (INIS)

    Kim, J. K.; Park, T. W.; Cebulska-Wasiewska, A.; Nili, M.

    2009-01-01

    Boron and gadolinium are among the nuclides that hold a unique property of being a neutron capture therapy agent. Neutron beams have often a considerable portion of gamma rays with fast neutrons. Gamma rays, as beam contaminants, can cause considerable damage to normal tissues even if such tissues do contain high boron concentrations. Materials and Methods: The modification of radio response in human lymphocytes pretreated with boron or gadolinium compound was studied by assessing the DNA damage using single cell gel electrophoresis, the comet assay. The lymphocytes from the human peripheral blood were irradiated with 0, 1, 2 and 4 Gy of gamma rays from a 60 Co isotopic source with or without pretreatment of boron or gadolinium compound for 10 minutes at 4 d egree C . Post-irradiation procedures included slide preparation, cell-lysing, unwinding and electrophoresis, neutralization, staining, and analytic steps, gel electrophoresis. Results: The results indicate that pretreatment with boron compound (50 n M or 250 n M of 10 B) is effective in reducing the radiosensitivity of the lymphocyte DNA. Conversely, pretreatment with gadolinium compound (50 n M) led to a dose-dependent increase in the radiosensitivity, most prominently with a dose of 4 Gy (P<0.001). Furthermore, when the lymphocytes were pretreated with a Combined mixture (1:1) of boron (250 n M) and gadolinium (50 n M) compounds, the reduced radiosensitivity was also observed.

  11. The hot working characteristics of a boron bearing and a conventional low carbon steel

    International Nuclear Information System (INIS)

    Stumpf, Waldo; Banks, Kevin

    2006-01-01

    Constitutive hot working constants were determined for an 11 ppm boron low carbon strip steel and compared from 875 to 1140 deg. C and strain rates of 0.001-2.5 s -1 to a high nitrogen low carbon strip steel. The boron steel showed a different hot working behaviour than the conventional steel with the steady state flow stress about 50-60% higher, the peak strain more than 50% higher and the eventual ferrite grain size about 40% smaller, if compared at the same temperature compensated strain rates or Z values. This difference persisted where the soaking temperature before compression was varied between 1140 and 1250 deg. C, proving that undissolved AlN in the boron-bearing steel was not responsible. With systematically varied linear cooling rates after hot working, the final ferrite grain size in the boron steel is finer and is independent of the two Z values applied during hot working. Retarded softening by dynamic recrystallisation during hot working in the boron containing steel is probably caused by boron solute drag of moving grain boundaries

  12. A Chemical Activation Study of the Unimolecular Reactions of CD3CD2CHCl2 and CHCl2CHCl2 with Analysis of the 1,1-HCl Elimination Pathway.

    Science.gov (United States)

    Larkin, Allie C; Nestler, Matthew J; Smith, Caleb A; Heard, George L; Setser, Donald W; Holmes, Bert E

    2016-10-03

    Chemically activated C2D5CHCl2 molecules were generated with 88 kcal mol-1 of vibrational energy by the recombination of C2D5 and CHCl2 radicals in a room temperature bath gas. The competing 2,1-DCl and 1,1-HCl unimolecular reactions were identified by the observation of the CD3CD=CHCl and CD3CD=CDCl products. The initial CD3CD2C-Cl carbene product from 1,1-HCl elimination rearranges to CD3CD=CDCl under the conditions of the experiments. The experimental rate constants were 2.7 x107 and 0.47 x107 s-1 for 2,1-DCl and 1,1-HCl elimination reactions, respectively, which corresponds to branching fractions of 0.84 and 0.16. The experimental rate constants were compared to calculated statistical rate constants to assign threshold energies of 54 and ≈ 66 kcal mol-1 for the 1,2-DCl and 1,1-HCl reactions, respectively. The statistical rate constants were obtained from models developed from electronic-structure calculations for the molecule and its transition states. The rate constant (5.3 x 107 s-1) for the unimolecular decomposition of CHCl2CHCl2 molecules formed with 82 kcal mol-1 of vibrational energy by the recombination of CHCl2 radicals also is reported. Based upon the magnitude of the calculated rate constant, 1,1-HCl elimination must contribute less than 15% to the reaction; 1,2-HCl elimination is the major reaction and the threshold energy is 59 kcal mol-1. Calculations also were done to analyze previously published rate constants for chemically activated CD2Cl-CHCl2 molecules with 86 kcal mol-1 of energy in order to obtain a better overall description of the nature of the 1,1-HCl pathway for 1,1-dichloroalkanes. The interplay of the threshold energies for the 2,1-HCl and 1,1-HCl reactions and the available energy determines the product branching fractions for individual molecules. The unusual nature of the transition state for 1,1-HCl elimination is discussed.

  13. Boron-doped nanocrystalline diamond electrodes for neural interfaces: in vivo biocompatibility evaluation

    Czech Academy of Sciences Publication Activity Database

    Alcaide, M.; Taylor, Andrew; Fjorback, M.; Zachar, V.; Pennisi, C.P.

    2016-01-01

    Roč. 10, Mar (2016), 1-9, č. článku 87. ISSN 1662-453X Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * neuroprosthetic interfaces * neural electrodes * boron-doped diamond * titanium nitride * foreign body reaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.566, year: 2016

  14. 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.)

  15. Versatile Boron Carbide-Based Visual Obscurant Compositions for Smoke Munitions

    Science.gov (United States)

    2015-04-17

    volatilize and disperse reaction products and inert diluents. Unlike the refractory oxides of common pyrotechnic fuels such as magnesium and aluminum, boron...peaks marked. [1] Akagi, R.; Ohtori, N.; Umesaki, N. Raman spectra of K2O–B2O3 glasses and melts. Journal of Non-Crystalline Solids. 2001

  16. New approaches to novel boronated porphyrins for neutron capture therapy

    International Nuclear Information System (INIS)

    Kahl, S.B.

    1986-01-01

    The use of boon compounds in the treatment of human cancer is based on the unique ability of nonradioactive 10 B nuclei to absorb thermal neutrons. The prompt nuclear reactions, which occur in neutron absorption, deliver a dose of nearly 2.8 MeV only in the vicinity of boron-containing cells, since the nuclear garments produced (alpha particles and recoil lithium atoms) travel only 10 to 15 μm. The practical, clinical use of this technique to date has been limited by the authors inability to target boron-containing compounds specifically to tumor cells in amounts sufficient for therapy and in a chemical form that has an acceptable level of toxicity. Porphyrins are one important and large class of compounds that are known to accumulate in practically all tumor systems yet examined. Such site-specific accumulation is not known to be based on any currently identifiable selective transport mechanism and yet is observed for both natural and synthetic porphyrins. Tetraphenylporphine sulfonate (TPPS) has been shown by Fairchild et al. to be an ideal model compound for assessing porphyrin uptake, and suitably boronated tetraphenyl porphine might be expected to behave similarly. This report describes the synthesis, properties, and preliminary biodistribution of such compounds

  17. Equations of state and melting curve of boron carbide in the high-pressure range of shock compression

    Energy Technology Data Exchange (ETDEWEB)

    Molodets, A. M., E-mail: molodets@icp.ac.ru; Golyshev, A. A.; Shakhrai, D. V. [Russian Academy of Sciences, Institute for Problems in Chemical Physics (Russian Federation)

    2017-03-15

    We have constructed the equations of state for crystalline boron carbide B{sub 11}C (C–B–C) and its melt under high dynamic and static pressures. A kink on the shock adiabat for boron carbide has been revealed in the pressure range near 100 GPa, and the melting curve with negative curvature in the pressure range 0–120 GPa has been calculated. The results have been used for interpreting the kinks on the shock adiabat for boron carbide in the pressure range of 0–400 GPa.

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

    International Nuclear Information System (INIS)

    Kageji, Teruyoshi; Nagahiro, Shinji; Kitamura, Katsushi; Nakagawa, Yoshinobu; Hatanaka, Hiroshi; Haritz, Dietrich; Grochulla, Frank; Haselsberger, Klaus; Gabel, Detlef

    2001-01-01

    Purpose: A cooperative study in Europe and Japan was conducted to determine the pharmacokinetics and boron uptake of sodium borocaptate (BSH: Na 2 B 12 H 11 SH), which has been introduced clinically as a boron carrier for boron neutron capture therapy in patients with glioblastoma. Methods and Materials: Data from 56 patients with glioblastoma who received BSH intravenous infusion were retrospectively reviewed. The pharmacokinetics were evaluated in 50 patients, and boron uptake was investigated in 47 patients. Patients received BSH doses between 12 and 100 mg/kg of body weight. For the evaluation, the infused boron dose was scaled linearly to 100 mg/kg BSH. Results: In BSH pharmacokinetics, the average value for total body clearance, distribution volume of steady state, and mean residence time was 3.6±1.5 L/h, 223.3±160.7 L, and 68.0±52.5 h, respectively. The average values of the boron concentration in tumor adjusted to 100 mg/kg BSH, the boron concentration in blood adjusted to 100 mg/kg BSH, and the tumor/blood boron concentration ratio were 37.1±35.8 ppm, 35.2±41.8 ppm, and 1.53±1.43, respectively. A good correlation was found between the logarithmic value of T adj and the interval from BSH infusion to tumor tissue sampling. About 12-19 h after infusion, the actual values for T adj and tumor/blood boron concentration ratio were 46.2±36.0 ppm and 1.70±1.06, respectively. The dose ratio between tumor and healthy tissue peaked in the same interval. Conclusion: For boron neutron capture therapy using BSH administered by intravenous infusion, this work confirms that neutron irradiation is optimal around 12-19 h after the infusion is started

  19. A technique to prepare boronated B72.3 monoclonal antibody for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Ranadive, G.N.; Rosenzweig, H.S.; Epperly, M.W.

    1993-01-01

    B72.3 monoclonal antibody has been successfully boronated using mercaptoundecahydro-closo-dodecaborate (boron cage compound). The reagent was incorporated by first reacting the lysine residues of the antibody with m-maleimidobenzoyl succinimide ester (MBS), followed by Michael addition to the maleimido group by the mercapto boron cage compound to form a physiologically stable thioether linkage. Boron content of the antibody was determined by atomic absorption spectroscopy. For biodistribution studies, boronated antibody was radioiodinated with iodogen. 125 I-labeled and boronated B72.3 monoclonal antibody demonstrated clear tumor localization when administered via tail vein injections to athymic nude mice bearing LS174-T tumor xenografts. Boronated antibody was calculated to deliver 10 6 boron atoms per tumor cell. Although this falls short of the specific boron content originally proposed as necessary for boron neutron capture therapy (BNCT), recent calculations suggest that far fewer atoms of 10 B per tumor cell would be necessary to effect successful BNCT when the boron is targeted to the tumor cell membrane. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H. [Institute of Physics, University of São Paulo, SP (Brazil)

    2014-11-11

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beams (LAMFI-USP) by the {sup 10}B(p,αγ({sup 7}Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10{sup 16} at/cm{sup 2}.

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

    International Nuclear Information System (INIS)

    Chou, F.I.; Chung, H.P.; Chung, R.J.; Wen, H.W.; Wei, Y.Y.; Kai, J.J.; Lui, W.Y.; Chi, C.W.

    2000-01-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

  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. 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

  5. Aluminum and boron phosphates as possible proton conductors

    International Nuclear Information System (INIS)

    Montoneri, E.; Salzano, F.J.; Giuffre, L.

    1985-05-01

    The chemical stability and conductivity of boron and aluminum phosphates in steam are reported for P/B and P/A1 atomic ratios greater than unity at temperatures from 100 0 to 280 0 C and steam pressures to 5 atmospheres. Al(PO 3 ) 3 and H 2 A1P 3 O 10 undergo the reactions Al (PO 3 ) 3 + H 2 ) in equilibrium H 2 AlP 3 O 10 and H 2 AlP 3 O 10 → AlPO 4 + H 2 O.P 2 O 5 (g). At 280 0 C and a steam pressure of 5 atmospheres gauge the product is mixture of AlPO 4 and H 2 ALP 3 O 10 , while the conductivity of this solid is in the range of 10 -2 ohm -1 cm -1 . The boron phosphates lose material and exhibit poor conductivity under similar conditions due to the instability of the BPO 4 phase as a result of the reaction 2BPO 4 + 6 H 2 O → B 2 O 3 .3H 2 O(g) + P 2 O 5 . 3H 2 O(g). As a result of dehydration or hydrolytic reactions an increase in water vapor pressure does not always lead to increased conductivity even at higher temperature

  6. Automatic chemical analysis of traces of boron in steel

    International Nuclear Information System (INIS)

    Ono, Akihiro; Yamaguchi, Naoharu; Matsumoto, Ryutaro

    1976-01-01

    The analyzer is composed of a sample changer, reagent addition devices, a distillation vessel, a color reaction vessel, a spectrophotometer, a controller, etc. The automatic procedure is performed according to the predetermined distillation and color reaction programs after dissolving 0.5 g of steel sample in aqua regia and fuming with sulfuric acid-phosphoric acid. The sample solution on the sample changer is transferred into the distillation vessel, where boron is distilled with methyl alcohol by heating and aeration. The distillate is collected in the distillate vessel, and a 1/2 aliquot is transferred into the color reaction vessel with small amounts of water. After the addition of glacial acetic acid and propionic anhydride, the distillate is circulated through the circulating pipe which is composed of an air blowing tube, a bubble remover, a flow cell and a drain valve. Oxalyl chloride (to eliminate water), sulfuric acid, the curcumin reagent (to form the boron complex) and an acetate buffer are added, and the absorbance of the solution is measured at 545 nm. The analytical results of steel samples were in good agreement with those obtained by the conventional method and with certified values. (auth.)

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

    Science.gov (United States)

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

    2014-01-01

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

  8. New functionalized mercaptoundecahydrododecaborate derivatives for potential application in boron neutron capture therapy: synthesis, characterization and dynamic visualization in cells.

    Science.gov (United States)

    Genady, Afaf R; Ioppolo, Joseph A; Azaam, Mohamed M; El-Zaria, Mohamed E

    2015-03-26

    A series of mercaptoundecahydrododecaborate (B12H11SH(2-), BSH) bearing mono- and dicarboxyalkyl derivatives was prepared, characterized, and their reactivity towards amidation and esterification in DMF was evaluated. Symmetrical alkylation of BSH was achieved by treatment with primary haloalkyl carboxylic acids in aqueous acetonitrile to produce S,S-bis(carboxyalkyl)sulfonium-undecahydro-closo-dodecaborate tetramethylammonium salts. Unsymmetrically substituted sulfonium salts were obtained through a similar treatment of cyanoethylthioether-undecahydro-closo-dodecaborate tetramethylammonium salt with haloalkyl carboxylic acid. Selective removal of the remaining cyanoethyl group upon treatment with tetramethylammonium hydroxide yielded S-carboxyalkyl-thioether-undecahydro-closo-dodecaborate ditetramethylammonium salts. N,N'-dicyclohexylcarbodiimide (DCC) activated amidation of S,S-bis(carboxyalkyl)sulfonium-undecahydro-closo-dodecaborate or S-carboxyalkyl-thioether-undecahydro-closo-dodecaborate tetramethylammonium salts with propargylamine provided the opportunity to install terminal acetylene groups for further conjugation. These compounds acted as powerful building blocks for the synthesis of a broad range of 1,4-disubstituted 1,2,3-triazole products in high yields, utilizing the Cu(I)-mediated click cycloaddition reaction. The synthesis of BSH-lipid with a two-tailed moiety was also achieved, by esterification of S,S-bis(carboxyethyl)sulfoniumundecahydro-closo-dodecaborate(1-) tetramethylammonium salt with 1,2-O-distearoyl-sn-3-glycerol, which may prove useful in the liposomal boron delivery system. The bio-compatibility of the azide-alkyne click reaction was then utilized by performing this reaction in cell culture. The distribution of BSH in HeLa cells could be visualized by treating the cells first with a BSH-alkyne compound and then with Alexa Fluor 488(®) azide dye. The BSH-dye conjugate, which did not wash out, revealed the distribution of boron in the He

  9. 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

  10. New techniques for producing thin boron films

    International Nuclear Information System (INIS)

    Thomas, G.E.

    1988-01-01

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

  11. Boron rates for triticale and wheat crops

    Directory of Open Access Journals (Sweden)

    Corrêa Juliano Corulli

    2005-01-01

    Full Text Available No reports are registered on responses to boron fertilization nutrient deficiency and toxicity in triticale crops. The aim of this study was to evaluate triticale response to different rates of boron in comparison to wheat in an hapludox with initial boron level at 0.08 mg dm-3 4 4 factorial design trial completely randomized blocks design (n = 4. Boron rates were 0; 0.62; 1.24 and 1.86 mg dm-3; triticale cultivars were IAC 3, BR 4 and BR 53 and IAPAR 38 wheat crop was used for comparison. The wheat (IAPAR 38 crop presented the highest boron absorption level of all. Among triticale cultivars, the most responsive was IAC 53, presenting similar characteristics to wheat, followed by BR 4; these two crops are considered tolerant to higher boron rates in soil. Regarding to BR 53, no absorption effect was observed, and the cultivars was sensitive to boron toxicity. Absorption responses differed for each genotype. That makes it possible to choose and use the best-adapted plants to soils with different boron rates.

  12. Hot flow behavior of boron microalloyed steels

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  13. Elastic modulus and fracture of boron carbide

    International Nuclear Information System (INIS)

    Hollenberg, G.W.; Walther, G.

    1978-12-01

    The elastic modulus of hot-pressed boron carbide with 1 to 15% porosity was measured at room temperature. K/sub IC/ values were determined for the same porosity range at 500 0 C by the double torsion technique. The critical stress intensity factor of boron carbide with 8% porosity was evaluated from 25 to 1200 0 C

  14. The use of boron trifluoride and alkoxiboroxines as extinguishants for magnesium alloy fires

    International Nuclear Information System (INIS)

    Newman, R.N.

    1987-11-01

    The extinguishants currently available for putting out magnesium alloy fires work by covering the burning fuel and excluding both the oxygen and nitrogen from the reaction zone. It has been reported that boron trifluoride and trimethoxi-and tributoxi-boroxine may act in a more specific chemical way on the combustion reactions. In this report an investigation into the effectiveness of these compounds on magnesium alloy fires is described. (author)

  15. 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.

  16. Cathodoluminescence of cubic boron nitride

    International Nuclear Information System (INIS)

    Tkachev, V.D.; Shipilo, V.B.; Zajtsev, A.M.

    1985-01-01

    Three optically active defects are detected in mono- and polycrystal cubic boron nitride (β-BN). Analysis of intensity of temperature dependences, halfwidth and energy shift of 1.76 eV narrow phononless line (center GC-1) makes it possible to interprete the observed cathodoluminescence spectra an optical analog of the Moessbaner effect. Comparison of the obtained results with the known data for diamond monocrystals makes it possible to suggest that the detected center GC-1 is a nitrogen vacancy . The conclusion, concerning the Moessbauer optical spectra application, is made to analyze structural perfection of β-BN crystal lattice

  17. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

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

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

    International Nuclear Information System (INIS)

    Billaud, C.

    2005-12-01

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

  19. Monte Carlo calculations on efficiency of boron neutron capture therapy for brain cancer

    International Nuclear Information System (INIS)

    Awadalla, Galaleldin Mohamed Suliman

    2015-11-01

    The search for ways to treat cancer has led to many different treatments, including surgery, chemotherapy, and radiation therapy. Among these treatments, boron neutron capture therapy (BNCT) has shown promising results. BNCT is a radiotherapy treatment modality that has been proposed to treat brain cancer. In this technique, cancerous cells are being injected with 1 0B and irradiated by thermal neutrons to increase the probability of 1 0B (n, a)7 L i reaction to occur. This reaction can potentially deliver a high radiation dose sufficient to kill cancer cells by concentrating boron in them. The short rang of 1 0B (n, a) 7 L i reaction limits the damage to only cancerous cells without affecting healthy tissues. The effectiveness and safety of radiotherapy are dependent on the radiation dose delivered to the tumor and healthy tissues. In this thesis, after reviewing the basics and working principles of boron neutron capture therapy (BNCT), monte Carlo simulations were carried out to model a thermal neutron source suitable for BNCT and to examine the performance of proposed model when used to irradiate a sample of boron containing both 1 0B and 1 1B isotopes. MCNP5 code was used to examine the modeled neutron source through different shielding materials. The results were presented, analyzed and discussed at the end of the work. (author)

  20. Photodegradation of aniline by goethite doped with boron under ultraviolet and visible light irradiation

    International Nuclear Information System (INIS)

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Liu, Linghua; Cheng, Dongsheng; Zhou, Huaidong

    2011-01-01

    Highlights: → Goethite modified by boron was prepared by sol-gel method in presence of boron acid at the low temperature. → B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. → The results showed that semiconductor photocatalytic reaction mechanism should exist in the process of aniline degradation with goethite and B-goethite as photocatalyst. -- Abstract: In the present study, goethite and goethite doped with boron (B-goethite) were employed to detect the presence or absence of semiconductor photocatalytic reaction mechanism in the reaction systems. B-goethite was prepared by sol-gel method in presence of boron acid in order to improve its photocatalystic efficiency under the ultraviolet and visible light irradiation. The optical properties of goethite and B-goethite were characterized by ultraviolet and visible absorption spectra and the result indicated that B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. Degradation of aniline was investigated in presence of goethite and B-goethite in aqueous solution. It was found that the B-goethite photocatalyst exhibited enhanced ultraviolet and visible light photocatalytic activity in degradation of aniline compared with the pristine goethite. The photocatalytic degradation mechanism of B-goethite was discussed.

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

    International Nuclear Information System (INIS)

    Zhu Daohong

    1990-08-01

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

  2. Synthesis of triazolyl methyl-substituted amino- and oxy-undeca-hydro-dodeca-borates for potential application in boron neutron capture therapy

    International Nuclear Information System (INIS)

    El-Zaria, M.E.; Genady, A.R.; Nakamura, H.; El-Zaria, M.E.; Genady, A.R.

    2010-01-01

    A general approach to the synthesis of triazole conjugates containing undeca-hydro-closo-dodeca-borate anions based on Huisgen 1, 3-dipolar cycloaddition is presented. Un-decahydro-closo-dodeca-borate anions bearing terminal alkyne groups were synthesized by the reaction of H 3 N-B 12 H 11 - or HO-B 12 H 11 2- with alkyne halides in N, N-dimethylformamide using KOH as a base. Variation of reaction time, alkyne halide concentration and steric demands of the alkyne halide resulted in the stepwise introduction of one to three alkyne groups into H 3 N-B 12 H 11 - . Two compounds {(CHCCH 2 )-N-B 12 H 11 - and (CHCCH 2 )O-B 12 H 11 2- } were crystallized for single-crystal X-ray diffraction studies. N- and O-alkyne un-decahydro-closo-dodeca-borate anions reacted with various functionalized azides including lipid, carborane, aryl and hydroxyalkyl groups. The current study provides various synthetic applications not only for BNCT but also for boron cluster materials. (authors)

  3. Chemistry and technology of boron and its compounds

    International Nuclear Information System (INIS)

    Zhigach, A.F.; Parfenov, B.P.; Svitsyn, R.A.

    1995-01-01

    The results of research dealing with development of technologies of boron trichloride, boron hydride, aminoderivative boron hydrides, metal borohydrides, carboranes, carborane-containing polymers, carried out at the institute of organoelemental compounds, are presented. Physicochemical properties of the compounds have been studied and analytical methods have been developed. Data on toxicity and fire hazard of boron compounds are provided

  4. 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

  5. Magnetic and structural properties of Sr0.75La0.25FexCu0.20O19 (10.40≤x≤11.80) hexagonal ferrites prepared by the solid-state reaction

    International Nuclear Information System (INIS)

    Yang, Yujie; Shao, Juxiang; Wang, Fanhou; Liu, Xiansong; Feng, Shuangjiu; Huang, Duohui; Yang, Junsheng; Jin, Chengguo

    2016-01-01

    In this study, the hexaferrite magnetic powders and magnets according to the formula Sr 0.75 La 0.25 Fe x Cu 0.20 O 19 , where x ranging from 10.40 to 11.80 with a step of 0.2 were prepared by the solid-state reaction. X-ray diffraction was performed to investigate the microstructures of the magnetic powders. The results show that a single magnetoplumbite phase is obtained for the magnetic powders with Fe content (10.60≤x≤11.60). For the magnetic powders with Fe content (x) of 10.40 or 11.80, magnetic impurities appear in the structure. A field emission scanning electron microscopy was hired to explore the micrographs of the magnets. The hexaferrite magnets are formed of hexagonal-shaped crystals. A magnetic properties test instrument was used in order to study the magnetic properties of the magnets. The remanence and maximum energy product first increase with Fe content (x) from 10.40 to 11.00 and then begin to decrease when Fe content (x) continues to increase. While the intrinsic coercivity and magnetic induction coercivity first increase with Fe content (x) from 10.40 to 11.20 and then decrease when Fe content (x)>11.20. - Highlights: • The hexaferrite Sr 0.75 La 0.25 Fe x Cu 0.20 O 19 (10.40≤x≤11.80) magnetic powders and magnets were synthesized by the solid-state reaction. • The hexaferrite magnets are formed of hexagonal-shaped crystals. • At Fe content (x)=11.00, B r and (BH) max for the magnets reach the maximum values. At Fe content (x)=11.20, H cj and H cb for the magnets reach the maximum values.

  6. Light elements burning reaction rates at stellar temperatures as deduced by the Trojan Horse measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lamia, L. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy); Spitaleri, C. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania, Italy and INFN-Laboratori Nazionali del Sud, Catania (Italy); La Cognata, M.; Palmerini, S.; Sergi, M. L. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Puglia, S. M. R. [INFN-Laboratori Nazionali del Sud, Catania, Italy and Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Catania (Italy)

    2015-02-24

    Experimental nuclear astrophysics aims at determining the reaction rates for astrophysically relevant reactions at their Gamow energies. For charged-particle induced reactions, the access to these energies is usually hindered, in direct measurements, by the presence of the Coulomb barrier between the interacting particles or by electron screening effects, which make hard the determination of the bare-nucleus S(E)-factor of interest for astrophysical codes. The use of the Trojan Horse Method (THM) appears as one of the most suitable tools for investigating nuclear processes of interest for astrophysics. Here, in view of the recent TH measurements, the main destruction channels for deuterium ({sup 2}H), for the two lithium {sup 6,7}Li isotopes, for the {sup 9}Be and the one for the two boron {sup 10,11}B isotopes will be discussed.

  7. Boron-containing catalysts for dry reforming of methane to synthesis gas

    KAUST Repository

    Takanabe, Kazuhiro

    2018-01-04

    The present invention uses a cobalt catalyst for carbon dioxide reforming of lower alkanes to synthesis gas having a cobalt catalyst on an oxide support where the supported cobalt catalyst has been modified with a boron precursor. The boron-treated cobalt catalyst systems as described herein show significant increases in the conversion of CH4 and CO2 during the dry reforming of methane (DRM) reaction as compared to traditional catalysts. Described herein are supported catalysts and methods of using the catalysts for the dry reforming of methane to synthesis gas, with the supported catalysts in the present invention include a boron-treated cobalt catalyst disposed on an oxide support. Also described herein are processes for preparing the supported catalysts.

  8. 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)

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  10. Boron effect on the microstructure of 9% Cr ferritic–martensitic steels

    International Nuclear Information System (INIS)

    Klimenkov, M.; Materna-Morris, E.; Möslang, A.

    2015-01-01

    Highlights: • Detailed TEM characterization of BN, M 23 C 6 , VN and TaC precipitates in B-alloyed EUROFER97. • Determination of B content influence on density and composition of M 23 C 6 and MX precipitates and herewith on microstructure. • α-Al 2 O 3 –BN–TaC–VN precipitation sequence of different phases during cooling was proposed. • Decreasing of thermal stability of microstructure with boron content was measured. - Abstract: The microstructure of reduces-activation 9Cr–WTaV steel alloyed with 83 and 1160 wt. ppm 10 B was detailed analysed using transmission electron microscopy. The influence of boron content on the precipitation behaviour of M 23 C 6 and MX (VN and TaC) phases and, hence, on the formation process of steel’s grain and lath structure was studied. VN precipitates, which play an important role in the stabilisation of the lath structure, exhibit most sensitive reaction on presence of boron. Their spatial density significantly reduces in the alloy with 83 ppm boron. In the steel with 1160 wt. ppm boron, no formation of VN was detected, whereas TaC particles precipitate at the lath and grain boundaries. These changes in the structure stabilisation mechanism lead to an increasing lath width and a decreasing thermal stability of laths and grains. Analytical investigations of several BN particles reveal their complex multi-phase structure and allow conclusions to be drawn with respect to their precipitation sequence

  11. CVD boron nitride infiltration of fibrous structures: properties of low temprature deposits

    International Nuclear Information System (INIS)

    Gebhardt, J.J.

    1973-01-01

    The pyrolytic infiltration of boron nitride and silica fibrous structures with boron nitride was investigated using the thermal decomposition of B-trichloroborazole (TCB) to provide the matrix surrounding felted and 4-directional braided constructions. The deposition precursor was generated on a continuous basis by the reaction between boron trichloride and ammonium chloride in a fixed bed reactor under conditions of total conversion of the trichloride: 3BCl 3 + 3NH 4 Cl = B 3 N 3 H 3 Cl 3 + 9HCl. Deposition rates in boron nitride felt specimens varied between 8 and 28 μm/h, depending on the distance from the exterior surface at the minimum deposition temperature used (1100 0 C ). Infiltration of 4-directional silica braids was poorer because of clogging of the fiber bundle surfaces and access paths to voids in the weave. Deposits prepared at 1100 0 C and above were stable to moisture and consisted of glassy transparent materials which had no discernible x-ray diffraction pattern. Heat treatment of low temperature deposits in nitrogen at 1800 0 C caused significant growth of the crystallites and the emergence of x-ray patterns characteristic of hexagonal boron nitride. Heat treatment in vacuum caused changes in the infrared spectrum which could be correlated with mass analyses of the gases evolved. Loss of hydrogen with amines predominated to about 1500 0 C above which point the loss of nitrogen became significant. (14 figures) (U.S.)

  12. 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.

  13. 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

  14. Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry

    Science.gov (United States)

    Kaczmarek, K.; Langer, G.; Nehrke, G.; Horn, I.; Misra, S.; Janse, M.; Bijma, J.

    2015-03-01

    A number of studies have shown that the boron isotopic composition (δ11B) and the B / Ca ratio of biogenic carbonates (mostly foraminifers) can serve as proxies for two parameters of the ocean's carbonate chemistry, rendering it possible to calculate the entire carbonate system. However, the B incorporation mechanism into marine carbonates is still not fully understood and analyses of field samples show species-specific and hydrographic effects on the B proxies complicating their application. Identifying the carbonate system parameter influencing boron incorporation is difficult due to the co-variation of pH, CO32- and B(OH)4-. To shed light on the question which parameter of the carbonate system is related to the boron incorporation, we performed culture experiments with the benthic symbiont-bearing foraminifer Amphistegina lessonii using a decoupled pH-CO32- chemistry. The determination of the δ11B and B / Ca ratios was performed simultaneously by means of a new in situ technique combining optical emission spectroscopy and laser ablation MC-ICP-MS. The boron isotopic composition in the tests gets heavier with increasing pH and B / Ca increases with increasing B(OH)4- / HCO3- of the culture media. The latter indicates that boron uptake of A. lessonii features a competition between B(OH)4- and HCO3-. Furthermore, the simultaneous determination of B / Ca and δ11B on single specimens allows for assessing the relative variability of these parameters. Among different treatments the B / Ca shows an increasing variability with increasing boron concentration in the test whereas the variability in the isotope distribution is constant.

  15. Violence of heavy-ion reactions from neutron multiplicity: 11 to 20A MeV /sup 20/Ne+ /sup 238/U

    International Nuclear Information System (INIS)

    Jahnke, U.; Ingold, G.; Hilscher, D.; Lehmann, M.; Schwinn, E.; Zank, P.

    1986-01-01

    The suitability of the neutron multiplicity as a gauge for the violence of medium-energy heavy-ion reactions is investigated for the first time. For this purpose the number of neutrons emitted from fission reactions induced by 220-, 290-, and 400-MeV /sup 20/Ne on /sup 238/U is registered event-by-event with a large 4π scintillator tank. It is shown that the neutron multiplicity is indeed closely related to the two quantities characterizing the violence: the induced total intrinsic excitation and the linear momentum transfer

  16. Cell cycle dependence of boron uptake in various boron compounds used for neutron capture therapy

    International Nuclear Information System (INIS)

    Yoshida, F.; Matsumura, A.; Shibata, Y.; Yamamoto, T.; Nose, T.; Okumura, M.

    2000-01-01

    In neutron capture therapy, it is important that the tumor take boron in selectively. Furthermore, it is ideal when the uptake is equal in each tumor cell. Some indirect proof of differences in boron uptake among neoplastic cell cycles has been documented. However, no investigation has yet measured boron uptake directly. Using flow cytometry, in the present study cells were sorted by G0/G1 phase and G2/M phase, and the boron concentration of each fraction was measured with inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The results were that BSH (sodiumborocaptate) and BPA (p-boronophenylalanine) had higher rates of boron uptake in the G2/M group than in the G0/G1 group. However, in BPA the difference was more prominent, which revealed a 2.2-3.3 times higher uptake of boron in the G2/M group than in the G0/G1 group. (author)

  17. 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)

  18. Raman spectra of hot-pressed boron suboxide

    CSIR Research Space (South Africa)

    Machaka, R

    2011-01-01

    Full Text Available on in- situ/online measurements (such as GIXRD, Raman Spectroscopy, FIB- Electron Microscopy) during (i) ion implantation, (ii) PLD growth of nanoparticles SW/MW-CNTs, oxide semiconductor multi-layer, metal/Si and metal/metal systems. Moreover, He...], aluminium magnesium boride ? AlMgB14 [8], and the newly synthesized boron subnitride ? B13N2 [9, 10]. With hardness values reported between 24 GPa and 45 GPa [7, 11, 12], B6O is sometimes considered to be the third hardest material only after diamond...

  19. Kerma factors in interaction of neutrons with boron carbide

    International Nuclear Information System (INIS)

    Bondarenko, I.M.

    1979-01-01

    Heat generation in neutron interactions with boron carbide B 10 ; B 11 and 12 C is calculated. Kerma-factors (kerma-kinetic energy released in materials) were calculated for neutron energies between 10 -4 eV and 15 MeV. No major simplifying assumptions are introduced, and the accuracy of the calculated kerma-factors depends only on availability and accuracy of the basic nuclear data. The ENDF/B-4 data and recent experimental information are used for the calculation of kerma-factors. Plots of these kerma-factors are presented in units of eVxb/atom and wtxsec/(cmxn) as a function of neutron energy

  20. Magnetostriction of the polycrystalline Fe{sub 80}Al{sub 20} alloy doped with boron

    Energy Technology Data Exchange (ETDEWEB)

    Bormio-Nunes, Cristina, E-mail: cristina@demar.eel.usp.br [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Teodoro dos Santos, Claudio; Botani de Souza Dias, Mateus [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael [Institut fuer Festkoerperphysik, TU Dresden, D-01062 Dresden (Germany)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer Fe{sub 80}Al{sub 20} polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. Black-Right-Pointing-Pointer B stabilizes {alpha}-FeAl phase and a coexistence of {alpha}-FeAl + Fe{sub 3}Al improves magnetostriction. Black-Right-Pointing-Pointer Presence of Fe{sub 2}B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe{sub 80}Al{sub 20} polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic {alpha}-FeAl and/or Fe{sub 3}Al and Fe{sub 2}B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of {alpha}-FeAl and a correspondent decrease of the Fe{sub 3}Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe{sub 2}B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe{sub 80}Al{sub 20} alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the {alpha}-FeAl and Fe{sub 3}Al phases could be reached.

  1. Identification of Intermetallic Compounds and Its Formation Mechanism in Boron Steel Hot-Dipped in Al-7 wt.% Mn Alloy

    Directory of Open Access Journals (Sweden)

    Sung-Yun Kwak

    2017-12-01

    Full Text Available In laser welding and hot stamping Al-Si-coated boron steel, there is a problem that the strength of the joint is lowered due to ferrite formation in the fusion zone. The purpose of this study is to develop an Al-7 wt.% Mn hot-dip coating in which Mn, an austenite stabilizing element, replaces the ferrite stabilizing element Si. The nucleation and formation mechanism of the reaction layer was studied in detail by varying the dipping time between 0 and 120 s at 773 °C. The microstructure and phase constitution of the reaction layer were investigated by various observational methods. Phase formation is discussed using a phase diagram calculated by Thermo-CalcTM. Under a 30 s hot-dipping process, no reaction occurred due to the formation of a Fe3O4 layer on the steel surface. The Fe3O4 layer decomposed by a reduction reaction with Al-Mn molten alloy, constituent elements of steel dissolved into a liquid, and the reaction-layer nucleus was formed toward the liquid phase. A coated layer consists of a solidified layer of Al and Al6Mn and a reactive layer formed beneath it. The reaction layer is formed mainly by inter-diffusion of Al and Fe in the solid state, which is arranged on the steel in the order of Al11Mn4 → FeAl3 (θ → Fe2Al5 (η phases, and the Fe3AlC (κ in several nm bands formed at the interface between the η-phase and steel.

  2. A reaction-based fluorescent sensor for detection of cyanide in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shan-Teng; Sie, Yi-Wun [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China); Wan, Chin-Feng [School of Applied Chemistry, Chung Shan Medical University, Taichung City 40201, Taiwan (China); Wu, An-Tai, E-mail: antai@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China)

    2016-05-15

    A simple boronic acid derivative was utilized as a reaction-based receptor for CN{sup −} in aqueous solution. The receptor showed a selective and sensitive response to CN{sup −} over other various anions via nucleophilic addition of CN{sup −} to the imine moiety of the boronic-based receptor.

  3. The Unimolecular Reactions of CF3CHF2 Studied by Chemical Activation: Assignment of Rate Constants and Threshold Energies to the 1,2-H Atom Transfer, 1,1-HF and 1,2-HF Elimination Reactions, and the Dependence of Threshold Energies on the Number of F-Atom Substituents in the Fluoroethane Molecules.

    Science.gov (United States)

    Smith, Caleb A; Gillespie, Blanton R; Heard, George L; Setser, D W; Holmes, Bert E

    2017-11-22

    The recombination of CF 3 and CHF 2 radicals in a room-temperature bath gas was used to prepare vibrationally excited CF 3 CHF 2 * molecules with 101 kcal mol -1 of vibrational energy. The subsequent 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions were observed as a function of bath gas pressure by following the CHF 3 , CF 3 (F)C: and C 2 F 4 product concentrations by gas chromatography using a mass spectrometer as the detector. The singlet CF 3 (F)C: concentration was measured by trapping the carbene with trans-2-butene. The experimental rate constants are 3.6 × 10 4 , 4.7 × 10 4 , and 1.1 × 10 4 s -1 for the 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions, respectively. These experimental rate constants were matched to statistical RRKM calculated rate constants to assign threshold energies (E 0 ) of 88 ± 2, 88 ± 2, and 87 ± 2 kcal mol -1 to the three reactions. Pentafluoroethane is the only fluoroethane that has a competitive H atom transfer decomposition reaction, and it is the only example with 1,1-HF elimination being more important than 1,2-HF elimination. The trend of increasing threshold energies for both 1,1-HF and 1,2-HF processes with the number of F atoms in the fluoroethane molecule is summarized and investigated with electronic-structure calculations. Examination of the intrinsic reaction coordinate associated with the 1,1-HF elimination reaction found an adduct between CF 3 (F)C: and HF in the exit channel with a dissociation energy of ∼5 kcal mol -1 . Hydrogen-bonded complexes between HF and the H atom migration transition state of CH 3 (F)C: and the F atom migration transition state of CF 3 (F)C: also were found by the calculations. The role that these carbene-HF complexes could play in 1,1-HF elimination reactions is discussed.

  4. Improved Results on Extraction of 11B(p, α0)8Be and 10B(p, α)7Be S(E)-Factor Through the Trojan Horse Method

    International Nuclear Information System (INIS)

    Puglia, S. M. R.; Lamia, L.; Romano, S.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Rapisarda, G. G.; Sergi, M. L.; Tudisco, S.; Carlin, N.; Del Santo, M. G.; Kroha, V.; Souza, F.; Szanto de Toledo, A.; Kubono, S.; Wakabayashi, Y.; Yamaguchi, H.; Li, C.; Qungang, W.

    2010-01-01

    In this work the analysis of the 10 B(23p, α) 7 Be and 11 B(p, α) 8 Be reactions, studied via the indirect Trojan Horse Method (THM), is discussed. In the astrophysical context of light nuclei LiBeB depletion, the above mentioned reactions are the main responsible for the destruction of boron in the stellar interior. The THM application allows their investigation in the astrophysically relevant energy region, around the Gamow Peak (≅10 keV), overcoming the problems due to the presence of the Coulomb barrier and electron screening effect. The experimental procedure and the preliminary results are shown.

  5. Diels-Alder Reactions of 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione

    Directory of Open Access Journals (Sweden)

    Shougang Hu

    2013-06-01

    Full Text Available 12-Hydroxy-9(10®20-5aH-abeo-abieta-1(10,8(9,12(13-triene-11,14-dione (quinone 2 served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.

  6. Viability study on using calcium carbonate for the boron adsorption process in waste waters

    International Nuclear Information System (INIS)

    Rodriguez Guerreiro, M. J.; Munoz Camacho, E.; Bernal Pita da Veiga, M. B.

    2009-01-01

    This study evaluates how viable it is to employ calcium carbonate for the boron adsorption process in waters that could be contaminated by this element. A residue form mussel shells-abundant in Galicia, northwestern Spain, was used. The data gathered from the experiments show that the performance of the boron adsorption within the sample is below 2%. Despite the inferior data obtained, the general aim was reached. An attempt was made to find solutions to the environmental problem caused by the residues mentioned above. (Author) 11 refs.

  7. Boron steel. I Part. Preparation; Aceros al Boro Parte I. Preparacion

    Energy Technology Data Exchange (ETDEWEB)

    Jaraiz Franco, E; Esteban Hernandez, J A

    1960-07-01

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

  8. Against Drought Stress Effect of Antioxidant Enzymes of Boron

    Directory of Open Access Journals (Sweden)

    Mahmut Doğan

    2013-04-01

    Full Text Available In this study, soybean seeds (Glycine max. L., cv., “A3935 were grown under controlled conditions (25±2 C composed of different boron compounds. In the experiment, 5 groups were determined respectively as potassium tetraborate tetrahydrate (1 mg/1, ammonium tetraborate tetrahydrate (1 mg/1, sodium boron hydride (1 mg/1, lithium tetraborate tetrahydrate (100 mg/1, and sodium tetraborate decahydrate (100 mg/1. The doses used in this study were determined according to the results of a preliminary study. Soybean seeds were exposed to different amounts of drought stress based on time (control, 3, 6, 9, 12, 15, and 18 days. Activities of antioxidant enzymes superoxide dismutase (SOD: EC 1.15.1.1, glutathione reductase (GR: EC 1.6.4.2, ascorbate peroxidase (APX: EC 1.11.1.11 and catalase (CAT: EC 1.11.1.6 measured. According to the results stress+potassium tetraborate tetrahydrate environment has increased the amount of CAT, decreased the amount GR, APX and SOD. Potassium tetraborate 0.1 mg / l dose administration is the most appropriate critical value, and the most important indicator of drought CAT enzyme found to give the best results.

  9. Ground-water pollution determined by boron isotope systematics

    International Nuclear Information System (INIS)

    Vengosh, A.; Kolodny, Y.; Spivack, A.J.

    1998-01-01

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

  10. Reactions of Hydrogen Chloride and Boron Trichloride with Trimethylsilylamino Groups

    Science.gov (United States)

    1989-04-04

    SUPPLEMENTARY NOTATION 17, COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and kientify by block number) FIELD ,,GROUP SU8 -GROUP...nitride preceramic polymers . Due to the low yield multistage synthesis, alternate routes to isomeric compositions and intermediates needed to be...Organo- metallic Polymers , Zeldin, M., Wynne, K. J., Allcock, H. R.; Ed, ACS Symposium Series 360. (4) Ebsworth, E.A.V. Volatile Silicon Compounds

  11. 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.

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

    International Nuclear Information System (INIS)

    Balapanova, B.S.; Zhajmina, R.E.; Serazetdinov, D.Z.

    1988-01-01

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

  13. Hydrogen-boron complexes in heavily boron-doped silicon treated with high concentration of hydrogen atoms

    International Nuclear Information System (INIS)

    Fukata, N.; Fukuda, S.; Sato, S.; Ishioka, K.; Kitajima, M.; Hishita, S.; Murakami, K.

    2006-01-01

    The formation of hydrogen (H)-related complexes was investigated in boron (B)-doped Si treated with high concentration of H. The isotope shifts of H-related Raman peaks by replacement of H to deuterium and 1 B to 11 B clearly showed the formation of the B-H complexes in which H directly bonds to B in Si. The results of the resistivity measurements suggested that the B acceptors are passivated via the formation of the B-H complexes, as well as the well-known passivation center in B-doped Si, namely, H-B passivation center

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

    Science.gov (United States)

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

    2011-12-01

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

  15. The application of FEL-EXPERT system in the interpretation of boron compounds toxicity

    International Nuclear Information System (INIS)

    Strouf, O.; Marik, V.

    1990-01-01

    The effect of substructural features of boron compounds on their toxicity (LD 50 , mice, i.p.) was studied using the FEL-EXPERT system developed by the Czech Technical University of Prague. A set of 108 compounds containing one or two boron atoms in their molecule was arbitrarily divided into three classes: compounds with high toxicity (LD 50 50 50 ≥1000 mg/kg). The compounds were represented by 70 substructural fragments, 27 of them being ''central substructures'' containing boron atom(s). The inference net consisted of 118 nodes (74 of the Bayesian type), 362 production rules and 74 context links. The total classification correctness was 98%. As a case-study, the classification of p-tolylboronic acid (LD 50 =520 mg/kg) and 4-carboxyphenylboronic acid (LD 50 =3838 mg/kg) was discussed. 4 figs., 2 tabs., 11 refs

  16. The irradiation behaviour of boron carbide/graphite between 800 and 1,1000C

    International Nuclear Information System (INIS)

    Hattenbach, K.; Hilgendorff, W.; Weiler, K.; Zimmermann, H.U.

    1975-01-01

    64 samples of boron carbide/graphite, a material used as burnable poison in high temperature reactors, were irradiated at temperatures between 800 and 1,100 0 C up to a fluence of 1-2 x 10 20 nvt. The following post-investigations were extended to dimensional measurements to determime a possible swelling or shrinking of the pellet, corrosion tests in completely desalinated water at 300 0 C, preparation of metallographic microsections to check for crack formation, determination of the helium hold back power and the thus involved gas chromatic analysis, as well as burn-up determinations by determining the boron 10/boron 11 ratio and the lithium concentration. (orig./LN) [de

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

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

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

  18. Cathodoluminescence of cubic boron nitride

    International Nuclear Information System (INIS)

    Tkachev, V.D.; Shipilo, V.B.; Zaitsev, A.M.

    1985-01-01

    Three types of optically active defect were observed in single-crystal and polycrystalline cubic boron nitride (β-BN). An analysis of the temperature dependences of the intensity, half-width, and energy shift of a narrow zero-phonon line at 1.76 eV (GC-1 center) made it possible to interpret the observed cathodoluminescence spectra as an optical analog of the Moessbauer effect. A comparison of the results obtained in the present study with the available data on diamond single crystals made it possible to identify the observed GC-1 center as a nitrogen vacancy. It was concluded that optical Moessbauer-type spectra can be used to analyze structure defects in the crystal lattice of β-BN

  19. Directional Track Selection Technique in CR39 SSNTD for lowyield reaction experiments

    Science.gov (United States)

    Ingenito, Francesco; Andreoli, Pierluigi; Batani, Dimitri; Bonasera, Aldo; Boutoux, Guillaume; Burgy, Frederic; Cipriani, Mattia; Consoli, Fabrizio; Cristofari, Giuseppe; De Angelis, Riccardo; Di Giorgio, Giorgio; Ducret, Jean Eric; Giulietti, Danilo; Jakubowska, Katarzyna

    2018-01-01

    There is a great interest in the study of p-11B aneutronic nuclear fusion reactions, both for energy production and for determination of fusion cross-sections at low energies. In this context we performed experiments at CELIA in which energetic protons, accelerated by the laser ECLIPSE, were directed toward a solid Boron target. Because of the small cross-sections at these energies the number of expected reactions is low. CR39 Solid-State Nuclear Track Detectors (SSNTD) were used to detect the alpha particles produced. Because of the low expected yield, it is difficult to discriminate the tracks due to true fusion products from those due to natural background in the CR39. To this purpose we developed a methodology of particle recognition according to their direction with respect to the detector normal, able to determine the position of their source. We applied this to the specific experiment geometry, so to select from all the tracks those due to particles coming from the region of interaction between accelerated protons and solid boron target. This technique can be of great help on the analysis of SSNTD in experiments with low yield reactions, but can be also generally applied to any experiment where particles reach the track detector with known directions, and for example to improve the detection limit of particle spectrometers using CR39.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

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

    International Nuclear Information System (INIS)

    Joel, D.D.; Coderre, J.A.; Chanana, A.D.

    1996-01-01

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

  2. 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...

  3. Internal stress control of boron thin film

    International Nuclear Information System (INIS)

    Satomi, N.; Kitamura, M.; Sasaki, T.; Nishikawa, M.

    1998-01-01

    The occurrence of stress in thin films has led to serious stability problems in practical use. We have investigated the stress in the boron films to find the deposition condition of the boron films with less stress. It was found that the stress in the boron film varies sufficiently from compressive to tensile stress, that is from -1.0 to 1.4 GPa, depending on the evaporation conditions, such as deposition rate and the substrate temperature. Hydrogen ion bombardment resulted in the enhancement of the compressive stress, possibly due to ion peening effect, while under helium ion bombardment, stress relief was observed. The boron film with nearly zero stress was obtained by the evaporation at a deposition rate of 0.5 nm s -1 and substrate temperature of 300 C. (orig.)

  4. Internal stress control of boron thin film

    Energy Technology Data Exchange (ETDEWEB)

    Satomi, N.; Kitamura, M.; Sasaki, T.; Nishikawa, M. [Osaka Univ., Suita (Japan). Graduate Sch. of Eng.

    1998-09-01

    The occurrence of stress in thin films has led to serious stability problems in practical use. We have investigated the stress in the boron films to find the deposition condition of the boron films with less stress. It was found that the stress in the boron film varies sufficiently from compressive to tensile stress, that is from -1.0 to 1.4 GPa, depending on the evaporation conditions, such as deposition rate and the substrate temperature. Hydrogen ion bombardment resulted in the enhancement of the compressive stress, possibly due to ion peening effect, while under helium ion bombardment, stress relief was observed. The boron film with nearly zero stress was obtained by the evaporation at a deposition rate of 0.5 nm s{sup -1} and substrate temperature of 300 C. (orig.) 12 refs.

  5. 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.

  6. 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

  7. Superplastic boronizing of duplex stainless steel under dual compression method

    International Nuclear Information System (INIS)

    Jauhari, I.; Yusof, H.A.M.; Saidan, R.

    2011-01-01

    Highlights: → Superplastic boronizing. → Dual compression method has been developed. → Hard boride layer. → Bulk deformation was significantly thicker the boronized layer. → New data on boronizing could be expanded the application of DSS in industries. - Abstract: In this work, SPB of duplex stainless steel (DSS) under compression method is studied with the objective to produce ultra hard and thick boronized layer using minimal amount of boron powder and at a much faster boronizing time as compared to the conventional process. SPB is conducted under dual compression methods. In the first method DSS is boronized using a minimal amount of boron powder under a fix pre-strained compression condition throughout the process. The compression strain is controlled in such a way that plastic deformation is restricted at the surface asperities of the substrate in contact with the boron powder. In the second method, the boronized specimen taken from the first mode is compressed superplastically up to a certain compressive strain under a certain strain rate condition. The process in the second method is conducted without the present of boron powder. As compared with the conventional boronizing process, through this SPB under dual compression methods, a much harder and thicker boronized layer thickness is able to be produced using a minimal amount of boron powder.

  8. Superplastic boronizing of duplex stainless steel under dual compression method

    Energy Technology Data Exchange (ETDEWEB)

    Jauhari, I., E-mail: iswadi@um.edu.my [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yusof, H.A.M.; Saidan, R. [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2011-10-25

    Highlights: {yields} Superplastic boronizing. {yields} Dual compression method has been developed. {yields} Hard boride layer. {yields} Bulk deformation was significantly thicker the boronized layer. {yields} New data on boronizing could be expanded the application of DSS in industries. - Abstract: In this work, SPB of duplex stainless steel (DSS) under compression method is studied with the objective to produce ultra hard and thick boronized layer using minimal amount of boron powder and at a much faster boronizing time as compared to the conventional process. SPB is conducted under dual compression methods. In the first method DSS is boronized using a minimal amount of boron powder under a fix pre-strained compression condition throughout the process. The compression strain is controlled in such a way that plastic deformation is restricted at the surface asperities of the substrate in contact with the boron powder. In the second method, the boronized specimen taken from the first mode is compressed superplastically up to a certain compressive strain under a certain strain rate condition. The process in the second method is conducted without the present of boron powder. As compared with the conventional boronizing process, through this SPB under dual compression methods, a much harder and thicker boronized layer thickness is able to be produced using a minimal amount of boron powder.

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

    International Nuclear Information System (INIS)

    Wielopolski, L.; Ciesielski, B.

    1995-01-01

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

  10. 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)

  11. Rare earth-iron-boron premanent magnets

    International Nuclear Information System (INIS)

    Ghendehari, M.H.

    1988-01-01

    This patent describes a method for producing rare earth-iron-boron permanent magnets containing added rare earth oxide, comprising the steps of: (a) mixing a particulate alloy containing at least one rare earth metal, iron, and boron with at least one particulate rare earth oxide; (b) aligning magnetic domains of the mixture in a magnetic field; (c) compacting the aligned mixture to form a shape; and (d) sintering the compacted shape

  12. Quantitative analysis of boron by neutron radiography

    International Nuclear Information System (INIS)

    Bayuelken, A.; Boeck, H.; Schachner, H.; Buchberger, T.

    1990-01-01

    The quantitative determination of boron in ores is a long process with chemical analysis techniques. As nuclear techniques like X-ray fluorescence and activation analysis are not applicable for boron, only the neutron radiography technique, using the high neutron absorption cross section of this element, can be applied for quantitative determinations. This paper describes preliminary tests and calibration experiments carried out at a 250 kW TRIGA reactor. (orig.) [de

  13. Level structures of 119Xe, 121Xe excited in (12C,3nγ) reactions and analysis of the hsub(11/2) bands in the IBF model

    International Nuclear Information System (INIS)

    Barci, V.; Gizon, J.; Gizon, A.

    1982-02-01

    Levels in 119 Xe, 121 Xe excited by the reactions 110 Cd, 112 Cd( 12 C,3nγ) 119 Xe, 121 Xe have been studied by in-beam γ-ray spectroscopic techniques. Several bands have been observed: hsub(11/2) and gsub(7/2) in 119 Xe, 121 Xe, a decoupled one in 121 Xe. A new level structure in 119 Xe found for the first time is assigned as the gsub(9/2) band generated by one hole in the gsub(9/2) neutron shell. The connections between these bands have been fixed in both nuclei. A detailed analysis is made for the hsub(11/2) level structure. An interpretation is given in terms of the interacting boson-fermion model where hsub(11/2), fsub(7/2) and hsub(9/2) fermion configurations are included

  14. 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

  15. Boronization on NSTX using Deuterated Trimethylboron

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  16. 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.

  17. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jilin [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Gu, Yunle [School of Material Science and Engineering, Wuhan Institute of Technology, Wuhan 430073 (China); Li, Zili [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Wang, Weimin, E-mail: wangwm@hotmail.com [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Fu, Zhengyi [The State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2013-06-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH{sub 4} played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B{sub 2}O{sub 3} and KBH{sub 4} as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH{sub 4} played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed.

  18. Synthesis of nano-sized amorphous boron powders through active dilution self-propagating high-temperature synthesis method

    International Nuclear Information System (INIS)

    Wang, Jilin; Gu, Yunle; Li, Zili; Wang, Weimin; Fu, Zhengyi

    2013-01-01

    Graphical abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed. Highlights: ► Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis method. ► The morphology, particle size and purity of the samples could be effectively controlled via changing the endothermic rate. ► The diluter KBH 4 played an important role in active dilution synthesis of amorphous nano-sized boron powders. ► The active dilution method could be further popularized and become a common approach to prepare various inorganic materials. - Abstract: Nano-sized amorphous boron powders were synthesized by active dilution self-propagating high-temperature synthesis (SHS) method at temperatures ranging from 700 °C to 850 °C in a SHS furnace using Mg, B 2 O 3 and KBH 4 as raw materials. Samples were characterized by X-ray powder diffraction (XRD), Laser particle size analyzer, Fourier transform infrared spectra (FTIR), X-ray energy dispersive spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission TEM (HRTEM). The boron powders demonstrated an average particle size of 50 nm with a purity of 95.64 wt.%. The diluter KBH 4 played an important role in the active dilution synthesis of amorphous nano-sized boron powders. The effects of endothermic reaction rate, the possible chemical reaction mechanism and active dilution model for synthesis of the product were also discussed

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

    Energy Technology Data Exchange (ETDEWEB)

    Mannix, A. J.; Zhou, X. -F.; Kiraly, B.; Wood, J. D.; Alducin, D.; Myers, B. D.; Liu, X.; Fisher, B. L.; Santiago, U.; Guest, J. R.; Yacaman, M. J.; Ponce, A.; Oganov, A. R.; Hersam, M. C.; Guisinger, N. P.

    2015-12-17

    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.

  20. Development of magnetic resonance technology for noninvasive boron quantification

    International Nuclear Information System (INIS)

    Bradshaw, K.M.

    1990-11-01

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

  1. 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...

  2. Research of boron conversion coating in neutron detector with boron deposited GEM

    International Nuclear Information System (INIS)

    Ye Di; Sun Zhijia; Zhou Jianrong; Wang Yanfeng; Yang Guian; Xu Hong; Chen Yuanbai; Xiao Yu; Diao Xungang

    2014-01-01

    GEM is a flourishing new gas detector and nowadays its technology become more mature. It has outstanding properties, such as excellent position resolution, high counting rate, radiation resistance, simple and flexible signal readout, can be large-area detector, wide application range. Detector with boron deposited GEM uses multilayer GEM with deposited boron film as neutron conversion carrier which reads out the information of neutron shot from the readout electrode with gas amplification from every GEM layer. The detector is high performance which can meet the demands of neutron detector of a new generation. Boron deposited neutron conversion electrode with boron deposited cathode and GEM included is the core part of the detector. As boron is a high-melting-point metalloid (> 2 000 ℃), electroplating and thermal evaporation are inappropriate ways. So finding a way to deposit boron on electrode which can meet the demands become a key technology in the development of neutron detector with boron deposited GEM. Compared with evaporation, sputtering has features such as low deposition temperature, high film purity, nice adhesive, thus is appropriate for our research. Magnetron sputtering is a improved way of sputtering which can get lower sputtering air pressure and higher target voltage, so that we can get better films. Through deposit process, the research uses magnetron sputtering to deposit pure boron film on copper electrode and GEM film. This method can get high quality, nice adhere, high purity, controllable uniformity, low cost film with high speed film formation. (authors)

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

    International Nuclear Information System (INIS)

    Kugel, H.W.; Timberlake, J.; Bell, R.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Tighe, W.; Hirooka, Y.

    1994-11-01

    Thirty one real-time boronizations were applied to PBX-M using the plasma erosion of solid target probes. More than 17 g of boron were deposited in PBX-M using this technique. The probes were positioned at the edge plasma to optimize vaporization 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

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

    International Nuclear Information System (INIS)

    Nigg, David W.

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    David W. Nigg

    2012-05-01

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

  6. 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.

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

    International Nuclear Information System (INIS)

    Yilmaz, A. Erdem; Boncukcuoglu, Recep; Kocakerim, M. Muhtar

    2007-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-22

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

  9. Biodistribution, toxicity and efficacy of a boronated porphyrin for boron neutron capture therapy

    International Nuclear Information System (INIS)

    Miura, Michiko; Micca, P.; Fairchild, R.; Slatkin, D.; Gabel, D.

    1992-01-01

    Boron-containing porphyrins may be useful for boron neutron capture therapy (BNCT) in the treatment of brain tumors. Porphyrins have been shown to accumulate in tumor tissue and to be essentially excluded from normal brain. However, problems of toxicity may prevent some boron-containing porphyrins from being considered for BNCT. The authors have synthesized the boronated porphyrin 2,4-bis-vinyl-o-nidocarboranyl-deuteroporphyrin IX (VCDP). Preliminary studies in tumor-bearing mice showed considerable uptake of boron at a total dose of 150 μg/gbw with low mortality. They now report that a total dose to mice of ∼ 275 μg VCDP/gbw administered in multiple intraperitoneal (ip) injections can provide 40-50μg B per gram of tumor with acceptable toxicity. Toxicity experiments and a preliminary trial of BNCT in mice given such doses are also reported

  10. Redistribution of boron in leaves reduces boron toxicity.

    Science.gov (United States)

    Reid, Robert J; Fitzpatrick, Kate L

    2009-11-01

    High soil boron (B) concentrations lead to the accumulation of B in leaves, causing the development of necrotic regions in leaf tips and margins, gradually extending back along the leaf. Plants vary considerably in their tolerance to B toxicity, and it was recently discovered that one of the tolerance mechanisms involved extrusion of B from the root. Expression of a gene encoding a root B efflux transporter was shown to be much higher in tolerant cultivars. In our current research we have shown that the same gene is also upregulated in leaves. However, unlike in the root, the increased activity of the B efflux transporter in the leaves cannot reduce the tissue B concentration. Instead, we have shown that in tolerant cultivars, these transporters redistribute B from the intracellular phase where it is toxic, into the apoplast which is much less sensitive to B. These results provide an explanation of why different cultivars with the same leaf B concentrations can show markedly different toxicity symptoms. We have also shown that rain can remove a large proportion of leaf B, leading to significant improvements of growth of both leaves and roots.

  11. Solar nuclear reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kocharov, G

    1978-04-01

    The current state of neutrino solar astrophysics is outlined, showing the contradictions between the experimental results of solar neutrino detection and the standard solar models constructed on the basis of the star structure and development theory, which give values for high-energy neutrino fluxes considerably exceeding the upper experimental limit. A number of hypotheses interpreting the experimental results are summarized. The hypotheses are critically assessed and experiments are recommended for refining or verifying experimental data. Also dealt with are nuclear reactions in the Sun, as is the attempt to interpret the anomalous by high /sup 3/He fluxes from the Sun and the relatively small amounts of solar neutrinos and gamma quanta. The importance is emphasized of the simultaneous and complex measurement of the fluxes of neutrons, gamma radiation, and isotopes of hydrogen, helium, and boron from the Sun as indicators of nuclear reactions in the Sun.

  12. 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

  13. Boronated monoclonal antibody 225.28S for potential use in neutron capture therapy of malignant melanoma

    International Nuclear Information System (INIS)

    Tamat, S.R.; Moore, D.E.; Patwardhan, A.; Hersey, P.

    1989-01-01

    The concept of conjugating boron cluster compounds to monoclonal antibodies has been examined by several groups of research workers in boron neutron capture therapy (BNCT). The procedures reported to date for boronation of monoclonal antibodies resulted in either an inadequate level of boron incorporation, the precipitation of the conjugates, or a loss of immunological activity. The present report describes the conjugation of dicesium-mercapto-undecahydrododecaborate (Cs2B12H11SH) to 225.28S monoclonal antibody directed against high molecular weight melanoma-associated antigens (HMW-MAA), using poly-L-ornithine as a bridge to increase the carrying capacity of the antibody and to minimize change in the conformational structure of antibody. The method produces a boron content of 1,300 to 1,700 B atoms per molecule 225.28S while retaining the immunoreactivity. Characterization in terms of the homogeneity of the conjugation of the boron-monoclonal antibody conjugates has been studied by gel electrophoresis and ion-exchange HPLC

  14. Preparation of a liquid nitrogen target for measurement of γ-ray in the 14N(n,γ)15N reaction as an intensity standard in energy region up to 11 MeV

    International Nuclear Information System (INIS)

    Hirano, M.; Obayashi, H.; Sakane, H.; Shibata, M.; Kawade, K.; Taniguchi, A.

    2001-01-01

    For determination of relative γ-ray intensities up to 11 MeV in the 14 N(n,γ) 15 N reaction, we have developed a liquid nitrogen (N 2 ) target which contain no hydrogen (H) to improve the accuracy of γ-ray intensities. The ratio of the relative uncertainties for the liquid nitrogen to that for the melamine (C 3 H 6 N 6 ) widely used was improved by a factor of 2 above 2.2 MeV and a factor of 3 - 6 below 2.2 MeV. It has been shown that the liquid nitrogen target is useful for reduction of the 2.2 MeV γ-ray from the 1 H(n,γ) 2 H reaction and improvement of statistics. (author)

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

    Science.gov (United States)

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

    2017-04-01

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

  16. Chemistry of nuclear recoil 18F atoms. VIII. Mechanisms and yields of caging reactions in liquid phase 1,1-difluoroethane and 1,1,1-trifluoroethane

    International Nuclear Information System (INIS)

    Manning, R.G.; Root, J.W.

    1976-01-01

    New procedures are reported for the specification of caging yields in nuclear recoil chemistry experiments. All five hot 18 F substitution channels in CH 3 CF 3 and CH 3 CHF 2 exhibit caging at large density. The respective total caged yields at 195 degreeK are 4.0% +- 0.6% and 5.6% +- 0.6%, and the total yields of stabilized substitution products are 8.9% +- 0.4% and 8.6% +- 0.6%. The simplest plausible caging mechanism involves primary Franck--Rabinowitsch radical recombination of 18 F atoms with aliphatic radicals. Density-variation results cannot be used for the qualitative detection of caging reactions unless excitation-stabilization complications have been shown to be unimportant

  17. Peculiarities of neutron interaction with boron containing semiconductors

    International Nuclear Information System (INIS)

    Didyk, A.Yu.; ); Hofman, A.; Institute of Atomic Energy, Otwock/Swierk; Vlasukova, L.A.

    2009-01-01

    The results of point defect creation calculation in B 4 C, BN and BP semiconductor single crystals irradiated in the fast neutron reactor IBR-2 are presented. It has been shown that during the thermal neutron interaction with light isotope boron atoms ( 10 B) the damage creation by means of fission nuclear reaction fragments (alpha particles and 7 Li recoil nuclei) exceeds the damage created by fast neutrons (E n > 0.1 MeV) by more than two orders of value. It has been concluded that such irradiation can create a well developed radiation defect structure in boron-containing crystals with nearly homogeneous vacancy depth distribution. This may be used in technological applications for more effective diffusion of impurities implanted at low energies or deposited onto the semiconductor surface. The developed homogeneous vacancy structure is very suitable for the radiation enhanced diffusion of electrically charged or neutral impurities from the surface into the technological depth of semiconductor devices under post irradiation treatment. (authors)

  18. Commissioning of accelerator based boron neutron capture therapy system

    International Nuclear Information System (INIS)

    Nakamura, S.; Wakita, A.; Okamoto, H.; Igaki, H.; Itami, J.; Ito, M.; Abe, Y.; Imahori, Y.

    2017-01-01

    Boron neutron capture therapy (BNCT) is a treatment method using a nuclear reaction of 10 B(n, α) 7 Li. BNCT can be deposited the energy to a tumor since the 10 B which has a higher cross-section to a neutron is high is concentrated on the tumor. It is different from conventional radiation therapies that BNCT expects higher treatment effect to radiation resistant tumors since the generated alpha and lithium particles have higher radiological biological effectiveness. In general, BNCT has been performed in research nuclear reactor. Thus, BNCT is not widely applied in a clinical use. According to recent development of accelerator-based boron neutron capture therapy system, the system has an adequate flux of neutrons. Therefore, National Cancer Canter Hospital, Tokyo, Japan is planning to install accelerator based BNCT system. Protons with 2.5 MeV are irradiated to a lithium target system to generate neutrons. As a result, thermal load of the target is 50 kW since current of the protons is 20.0 mA. Additionally, when the accelerator-based BNCT system is installed in a hospital, the facility size is disadvantage in term of neutron measurements. Therefore, the commissioning of the BNCT system is being performed carefully. In this article, we report about the commissioning. (author)

  19. The development and preliminary testing of new boronated agents for BNCT based on PET derived data

    International Nuclear Information System (INIS)

    Nichols, T.; Kabalka, G.; Kahn, M.; Das, B.; Das, S.; Bao, W.; Miller, L.

    2000-01-01

    Positron emission tomography (PET) has been utilized at the University of Tennessee for evaluating a variety of tumors including glioblastoma multiforme (GBM) and metastatic malignant melanoma (MM). Studies have been carried out utilizing fluorine-18 labeled p-boronophenylalanine ( 18 F-BPA) and other unnatural amino acids. A comparison of PET studies obtained using 18 F-BPA and a carbon-11 labeled cyclobutane-based amino acid ( 11 C-ACBC) revealed that 11 C-ACBC localized effectively in GBM tumors. Based on these results, we have prepared a series of boronated, aminocyclobutanecarboxylic acids. Preliminary uptake and cell toxicity studies have been carried out and show that many of the agents are not toxic. In one instance, a biodistribution study carried out using nude mice implanted with a human glioblastoma tumor, the tumor to normal tissue uptake of boron exceeds that observed for BPA. (author)

  20. Boron removal in radioactive liquid waste by forward osmosis membrane

    Energy Technology Data Exchange (ETDEWEB)

    Doo Seong Hwang; Hei Min Choi; Kune Woo Lee; Jei Kwon Moon [KAERI, Daejeon (Korea, Republic of)

    2013-07-01

    This study investigated the treatment of boric acid contained in liquid radioactive waste using a forward osmosis membrane. The boron permeation through the membrane 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 of the osmotic driving force. The boron flux decreases slightly with the salt concentration, but is not heavily influenced by a low salt concentration. The boron flux increases linearly with the concentration of boron. No element except for boron was permeated through the FO membrane in the multi-component system. The maximum boron flux is obtained in an active layer facing a draw solution orientation of the CTA-ES membrane under conditions of less than pH 7 and high osmotic pressure. (authors)