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Sample records for boron dose enhancement

  1. Effect of diameter of nanoparticles and capture cross-section library on macroscopic dose enhancement in boron neutron capture therapy

    Science.gov (United States)

    Farhood, Bagher

    2014-01-01

    Purpose The aim of this study is evaluation of the effect of diameter of 10B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT). Material and methods MCNPX Monte Carlo code was used for simulation of a 252Cf source, a soft tissue phantom and a tumor containing 10B nanoparticles. Using 252Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of 10B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated. Results There is not a linear relationship between the average MDEF value and nanoparticles’ diameter but the average MDEF grows with increased concentration of 10B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of 10B nanoparticles. Conclusions Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements. PMID:25834582

  2. THE EFFECT OF BORON DOSES ON PARICA (Schizolobium amazonicum Herb.

    Directory of Open Access Journals (Sweden)

    Sebastião Ferreira de Lima

    2003-07-01

    Full Text Available An experiment was conducted in a greenhouse in order to evaluate the effects of boron on parica growth and on concentration and contents of macro and micronutrients indry matter of shoots and roots. Six treatments constituted by boron doses of 0.0; 0.1; 0.3; 0.9;1.5 and 2.1 mg/dm3 in four replications were used. It was evaluated the characteristics:visual diagnostic, plants height and diameter, dry matter production of shoots and roots,concentration and contents of nutrients in dry matter of shoots and roots. The symptoms ofdeficiency can be observed in new leaves and roots and the toxicity in older leaves. Bothboron deficiency and excess inhibits plants growth, but toxicity is more damaging. The Comportamento do paricá (Schizolobium amazonicum Herb. submetido ...193approximate dose of 0 Estimate of average equilibrium moisture content of wood for 26Brazilian states, by Hailwood and Harrobin one hydrate sorption theory equation.15mg/dm3 was the best for plants growth in MSPA and MSRA. The concentration of boronincreased in MSPA and MSRA with application of increasing concentration of B, with a smallreduction in concentration of MSRA from the concentration 1.9 mg/dm3. The toxicity of boronbegins when concentration reaches 36.06 mg/dm3 in shoots and 32.38 in roots. The contentsof all nutrients, except Mn and Fe in MSPA and Cu, Fe and B in MSRA, followed its own drymatter production curves.

  3. Design of a boron neutron capture enhanced fast neutron therapy assembly

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonglu [Georgia Inst. of Technology, Atlanta, GA (United States)

    2006-12-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm 10B) to measure dose due to boron neutron capture. The

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

    Science.gov (United States)

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

    2006-12-01

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

  5. The three dimensional map of dose components in a head phantom for boron neutron capture therapy

    OpenAIRE

    Bavarnegin Elham; Sadremomtaz Alireza; Khalafi Hossein

    2013-01-01

    The in-phantom measurement of physical dose distribution and construction of a convenient phantom is very important for boron neutron capture therapy planning validation. In this study we have simulated a head phantom, suggested for construction in boron neutron capture therapy facilities, and calculated all relevant dose components inside of it using the Monte Carlo code MCNPX. A “generic” epithermal neutron beam with a broad neutron spectrum, similar to beams used for neutron capture ...

  6. Boron Diffused Thermoluminescent Surface Layer in LiF TLDs for Skin Dose Assessments

    DEFF Research Database (Denmark)

    Christensen, Poul; Majborn, Benny

    1980-01-01

    A new high-temperature glow peak produced in a thin surface layer of LiF TLDs by diffusion of boron into the LiF material has been studied for skin dose assessments in personnel dosimetry.......A new high-temperature glow peak produced in a thin surface layer of LiF TLDs by diffusion of boron into the LiF material has been studied for skin dose assessments in personnel dosimetry....

  7. 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...... to an enhanced self- and B diffusion in Ge. Analysis of the experimental profiles yields data for the diffusion of self-interstitials (I ) and the thermal equilibrium concentration of BI pairs in Ge. The temperature dependence of these quantities provides the migration enthalpy of I and formation enthalpy of BI...

  8. Boron

    Science.gov (United States)

    ... an eye wash. Boron was used as a food preservative between 1870 and 1920, and during World Wars ... chemical symbol), B (symbole chimique), Borate, Borate de Sodium, Borates, Bore, Boric Acid, Boric Anhydride, Boric Tartrate, ...

  9. Dose estimation for internal organs during boron neutron capture therapy for body-trunk tumors.

    Science.gov (United States)

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

    2014-06-01

    Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease.

  10. The three dimensional map of dose components in a head phantom for boron neutron capture therapy

    Directory of Open Access Journals (Sweden)

    Bavarnegin Elham

    2013-01-01

    Full Text Available The in-phantom measurement of physical dose distribution and construction of a convenient phantom is very important for boron neutron capture therapy planning validation. In this study we have simulated a head phantom, suggested for construction in boron neutron capture therapy facilities, and calculated all relevant dose components inside of it using the Monte Carlo code MCNPX. A “generic” epithermal neutron beam with a broad neutron spectrum, similar to beams used for neutron capture therapy clinical trials, was used. The calculated distributions of all relevant dose components in brain tissue equivalent were compared with those in water. The results show that water is a suitable dosimetry material and that the simulated head phantom is a suitable design for producing accurate three-dimensional maps of dose components at enough points inside of the phantom for boron neutron capture therapy dosimetry measurements and the use of these dose maps in beam development and benchmarking of computer-based treatment codes.

  11. Gel dosimeters as useful dose and thermal-fluence detectors in Boron Neutron Capture Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Valente, M. [Department of Physics of the University and INFN, Via Celoria 16, I-20133 Milan (Italy); Moss, R.L.; Daquino, G.G.; Nievaart, V.A. [Joint Research Centre, Institute for Energy, P.O. Box 2, NL-1755ZG Petten, The Netherlands (Netherlands); Mariani, M.; Vanossi, E. [Department of Nuclear Engineering of Polytechnic, CESNEF, Via Ponzio, 34/3 - I-20133 Milan (Italy); Carrara, M. [Medical Physics Department, National Cancer Institute, Via Venezian 1, I-20131, Milan (Italy)

    2006-07-01

    The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-21

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

  13. Improvement of dose distribution by central beam shielding in boron neutron capture therapy

    Science.gov (United States)

    Sakurai, Yoshinori; Ono, Koji

    2007-12-01

    Since boron neutron capture therapy (BNCT) with epithermal neutron beams started at the Kyoto University Reactor (KUR) in June 2002, nearly 200 BNCT treatments have been carried out. The epithermal neutron irradiation significantly improves the dose distribution, compared with the previous irradiation mainly using thermal neutrons. However, the treatable depth limit still remains. One effective technique to improve the limit is the central shield method. Simulations were performed for the incident neutron energies and the annular components of the neutron source. It was clear that thermal neutron flux distribution could be improved by decreasing the lower energy neutron component and the inner annular component of the incident beam. It was found that a central shield of 4-6 cm diameter and 10 mm thickness is effective for the 12 cm diameter irradiation field. In BNCT at KUR, the depth dose distribution can be much improved by the central shield method, resulting in a relative increase of the dose at 8 cm depth by about 30%. In addition to the depth dose distribution, the depth dose profile is also improved. As the dose rate in the central area is reduced by the additional shielding, the necessary irradiation time, however, increases by about 30% compared to normal treatment.

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

    OpenAIRE

    Elham Bavarnegin; Alireza Sadremomtaz; Hossein Khalafi; Yaser Kasesaz

    2016-01-01

    Aim: Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. Materials and Methods: The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. Results: Different dose components have been measured in a head phantom which has been designed an...

  15. Monte Carlo simulation of depth dose distribution in several organic models for boron neutron capture therapy

    Science.gov (United States)

    Matsumoto, T.

    2007-09-01

    Monte Carlo simulations are performed to evaluate depth-dose distributions for possible treatment of cancers by boron neutron capture therapy (BNCT). The ICRU computational model of ADAM & EVA was used as a phantom to simulate tumors at a depth of 5 cm in central regions of the lungs, liver and pancreas. Tumors of the prostate and osteosarcoma were also centered at the depth of 4.5 and 2.5 cm in the phantom models. The epithermal neutron beam from a research reactor was the primary neutron source for the MCNP calculation of the depth-dose distributions in those cancer models. For brain tumor irradiations, the whole-body dose was also evaluated. The MCNP simulations suggested that a lethal dose of 50 Gy to the tumors can be achieved without reaching the tolerance dose of 25 Gy to normal tissue. The whole-body phantom calculations also showed that the BNCT could be applied for brain tumors without significant damage to whole-body organs.

  16. Dose monitoring for boron neutron capture therapy using a reactor-based epithermal neutron beam

    Science.gov (United States)

    Raaijmakers, C. P. J.; Nottelman, E. L.; Konijnenberg, M. W.; Mijnheer, B. J.

    1996-12-01

    The aims of this study were (i) to determine the variation with time of the relevant beam parameters of a clinical reactor-based epithermal neutron beam for boron neutron capture therapy (BNCT) and (ii) to test a monitoring system for its applicability to monitor the dose delivered to the dose specification point in a patient treated with BNCT. For this purpose two fission chambers covered with Cd and two GM counters were positioned in the beam-shaping collimator assembly of the epithermal neutron beam. The monitor count rates were compared with in-phantom reference measurements of the thermal neutron fluence rate, the gamma-ray dose rate and the fast neutron dose rate, at a constant reactor power, over a period of 2 years. Differences in beam output, defined as the thermal neutron fluence rate at 2 cm depth in a phantom, of up to 15% were observed between various reactor cycles. A decrease in beam output of about 5% was observed in each reactor cycle. An unacceptable decrease of 50% in beam output due to malfunctioning of the beam filter assembly was detected. For safe and accurate treatment of patients, on-line monitoring of the beam is essential. Using the calibrated monitor system, the standard uncertainty in the total dose at depth due to variations with time of the beam output parameters has been reduced to a clinically acceptable value of 1% (one standard deviation).

  17. Enhanced boronizing kinetics of alloy steel assisted by surface mechanical attrition treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Haopeng, E-mail: hpyang1993@163.com; Wu, Xiaochun, E-mail: xcwu@staff.shu.edu.cn; Yang, Zhe; Pu, Shengjun; Wang, Hongbin

    2014-03-25

    Highlights: • Nanostructured surface layer is fabricated on H13 steel assisted by SMAT. • The boronizing kinetics of SMAT sample can be enhanced remarkably. • Borided layer can delay fatigue cracks initiation and impede their propagation. -- Abstract: A nanostructured surface layer was fabricated on AISI H13 steel by means of surface mechanical attrition treatment (SMAT). Boronizing behaviors of the SMAT samples were systematically investigated in comparison with their coarse-grained counterparts. The boron diffusion depth of the SMAT sample with pack boriding treatment at 600 °C for 2 h was about 8 μm, which was much deeper than that of the coarse-grained sample. A much thicker borided layer on the SMAT sample can be synthesized by a duplex boronizing treatment at 600 °C followed by at a higher temperature. The borided layer was composed with monophase of Fe{sub 2}B and the growth of it exhibited a (0 0 2) preferred orientation. Moreover, the activation energy of boron diffusion for the SMAT sample is 140.3 kJ/mol, which is much lower than 209.4 kJ/mol for the coarse-grained counterpart. The results indicate that the boronizing kinetics can be significantly enhanced in the SMAT sample with a duplex boronizing treatment. Furthermore, the thermal fatigue tests show that the borided layer with excellent oxidation resistance and mechanical strength at elevated temperatures could effectively delay the thermal fatigue cracks initiation and impede their propagation. Therefore, the thermal fatigue property of H13 steel with a duplex boronizing treatment can be improved remarkably.

  18. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

    Science.gov (United States)

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-02-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

  19. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles.

    Science.gov (United States)

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-02-02

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-14

    This project, since its start in 2007—entitled “Networks of boron-doped carbon nanopores for low-pressure reversible hydrogen storage” (2007-10) and “New pathways and metrics for enhanced, reversible hydrogen storage in boron-doped carbon nanospaces” (2010-13)—is in support of the DOE's National Hydrogen Storage Project, as part of the DOE Hydrogen and Fuel Cells Program’s comprehensive efforts to enable the widespread commercialization of hydrogen and fuel cell technologies in diverse sectors of the economy. Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on board a wide range of vehicle platforms, at energy densities comparable to gasoline, without compromising passenger or cargo space, remains an outstanding technical challenge. Of the main three thrust areas in 2007—metal hydrides, chemical hydrogen storage, and sorption-based hydrogen storage—sorption-based storage, i.e., storage of molecular hydrogen by adsorption on high-surface-area materials (carbons, metal-organic frameworks, and other porous organic networks), has emerged as the most promising path toward achieving the 2017 DOE storage targets of 0.055 kg H2/kg system (“5.5 wt%”) and 0.040 kg H2/liter system. The objective of the project is to develop high-surface-area carbon materials that are boron-doped by incorporation of boron into the carbon lattice at the outset, i.e., during the synthesis of the material. The rationale for boron-doping is the prediction that boron atoms in carbon will raise the binding energy of hydro- gen from 4-5 kJ/mol on the undoped surface to 10-14 kJ/mol on a doped surface, and accordingly the hydro- gen storage capacity of the material. The mechanism for the increase in binding energy is electron donation from H2 to electron-deficient B atoms, in the form of sp2 boron-carbon bonds. Our team is proud to have

  1. Boron nitride nanotube-enhanced osteogenic differentiation of mesenchymal stem cells.

    Science.gov (United States)

    Li, Xia; Wang, Xiupeng; Jiang, Xiangfen; Yamaguchi, Maho; Ito, Atsuo; Bando, Yoshio; Golberg, Dmitri

    2016-02-01

    The interaction between boron nitride nanotubes (BNNTs) layer and mesenchymal stem cells (MSCs) is evaluated for the first time in this study. BNNTs layer supports the attachment and growth of MSCs and exhibits good biocompatibility with MSCs. BNNTs show high protein adsorption ability, promote the proliferation of MSCs and increase the secretion of total protein by MSCs. Especially, BNNTs enhance the alkaline phosphatase (ALP) activity as an early marker of osteoblasts, ALP/total protein and osteocalcin (OCN) as a late marker of osteogenic differentiation, which shows that BNNTs can enhance osteogenesis of MSCs. The release of trace boron and the stress on cells exerted by BNNTs with a fiber structure may account for the enhanced differentiation of MSCs into osteoblasts. Therefore BNNTs are potentially useful for bone regeneration in orthopedic applications.

  2. Enhanced Sintering of Boron Carbide-Silicon Composites by Silicon

    Science.gov (United States)

    Zeng, Xiaojun; Liu, Weiliang

    2016-11-01

    Boron carbide (B4C)-silicon (Si) composites have been prepared by aqueous tape casting, laminating, and spark plasma sintering (SPS). The influences of silicon (Si) content on the phases, microstructure, sintering properties, and mechanical properties of the obtained B4C-Si composites are studied. The results indicate that the addition of Si powder can act as a sintering aid and contribute to the sintering densification. The addition of Si powder can also act as a second phase and contribute to the toughening for composites. The relative density of B4C-Si composites samples with adding 10 wt.% Si powder prepared by SPS at 1600 °C and 50 MPa for 8 min is up to 98.3%. The bending strength, fracture toughness, and Vickers hardness of the sintered samples are 518.5 MPa, 5.87 MPa m1/2, and 38.9 GPa, respectively. The testing temperature-dependent high-temperature bending strength and fracture toughness can reach a maximum value at 1350 °C. The B4C-Si composites prepared at 1600, 1650, and 1700 °C have good high-temperature mechanical properties. This paper provides a facile low-temperature sintering route for B4C ceramics with improved properties.

  3. Enhanced Sintering of Boron Carbide-Silicon Composites by Silicon

    Science.gov (United States)

    Zeng, Xiaojun; Liu, Weiliang

    2016-09-01

    Boron carbide (B4C)-silicon (Si) composites have been prepared by aqueous tape casting, laminating, and spark plasma sintering (SPS). The influences of silicon (Si) content on the phases, microstructure, sintering properties, and mechanical properties of the obtained B4C-Si composites are studied. The results indicate that the addition of Si powder can act as a sintering aid and contribute to the sintering densification. The addition of Si powder can also act as a second phase and contribute to the toughening for composites. The relative density of B4C-Si composites samples with adding 10 wt.% Si powder prepared by SPS at 1600 °C and 50 MPa for 8 min is up to 98.3%. The bending strength, fracture toughness, and Vickers hardness of the sintered samples are 518.5 MPa, 5.87 MPa m1/2, and 38.9 GPa, respectively. The testing temperature-dependent high-temperature bending strength and fracture toughness can reach a maximum value at 1350 °C. The B4C-Si composites prepared at 1600, 1650, and 1700 °C have good high-temperature mechanical properties. This paper provides a facile low-temperature sintering route for B4C ceramics with improved properties.

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

    CERN Document Server

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

    2014-01-01

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

  5. Doses de boro no desenvolvimento de copo-de-leite em solução nutritiva Boron doses in the development of calla lily in nutrient solution

    Directory of Open Access Journals (Sweden)

    Roseane Rodrigues de Souza

    2010-12-01

    Full Text Available O boro desempenha funções importantes em processos biológicos das plantas, como a síntese e estruturação da parede celular, lignificação, metabolismo e transporte de carboidratos, além de participar da divisão e diferenciação celular em tecidos meristemáticos. No entanto, as necessidades nutricionais para o cultivo de copo-de-leite, especialmente de boro, ainda são pouco conhecidas. Assim, objetivou-se avaliar os efeitos de diferentes doses de boro no crescimento e desenvolvimento, teor e acúmulo desse nutriente em plantas de copo-de-leite cultivadas em solução nutritiva. Mudas micropropagadas foram submetidas aos tratamentos com as doses de 0,05; 0,25; 0,50; 0,75; 1,00 e 2,00 mg L-1 de boro em solução nutritiva de Hoagland & Arnon diluída a 30% de sua força iônica. O delineamento experimental foi o inteiramente casualizado, com dez repetições. As plantas não manifestaram sintomas visuais de deficiência ou de toxidez de boro, no entanto, o sistema radicular das plantas cultivadas na dose de 0,05 mg L-1 de boro apresentou-se com o crescimento reduzido. A melhor dose para o desenvolvimento adequado de plantas de copo-de-leite em solução nutritiva é de 1,20 mg L-1 de boro.Boron has essential functions in plant biological processes such as cell wall synthesis and structuralization, lignification, carbohydrates metabolism and transport. This element also acts in cell division and differentiation in meristematic tissues. However, the nutritional needs for calla lily cultivation, and especially boron needs, are still poorly known. Thus, the objective of this work was to evaluate the effects of different boron doses on growth and development, content and accumulation of boron in calla lily plants grown in a nutrient solution. Micropropagated seedlings were submitted to treatments with the doses 0.05; 0.25; 0.50; 0.75; 1.00 and 2.00 mg L-1 boron in Hoagland & Arnon nutrient solution diluted to 30% of its ionic force. The

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

    Science.gov (United States)

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

    2016-02-23

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

  7. Investigation of Dose Distribution in Mixed Neutron-Gamma Field of Boron Neutron Capture Therapy using N-Isopropylacrylamide Gel

    Directory of Open Access Journals (Sweden)

    Elham Bavarnegin

    2017-02-01

    Full Text Available Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT. In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  8. Enhanced optoelectronic performances of vertically aligned hexagonal boron nitride nanowalls-nanocrystalline diamond heterostructures

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Hoang, Duc Quang; Kunuku, Srinivasu; Korneychuk, Svetlana; Turner, Stuart; Pobedinskas, Paulius; Drijkoningen, Sien; van Bael, Marlies K.; D' Haen, Jan; Verbeeck, Johan; Leou, Keh-Chyang; Lin, I.-Nan; Haenen, Ken

    2016-07-01

    Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/μm, a high FEE current density of 1.48 mA/cm2 and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/μm with 0.21 mA/cm2 FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission.

  9. Enhanced optoelectronic performances of vertically aligned hexagonal boron nitride nanowalls-nanocrystalline diamond heterostructures.

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Hoang, Duc Quang; Kunuku, Srinivasu; Korneychuk, Svetlana; Turner, Stuart; Pobedinskas, Paulius; Drijkoningen, Sien; Van Bael, Marlies K; D' Haen, Jan; Verbeeck, Johan; Leou, Keh-Chyang; Lin, I-Nan; Haenen, Ken

    2016-07-11

    Field electron emission (FEE) properties of vertically aligned hexagonal boron nitride nanowalls (hBNNWs) grown on Si have been markedly enhanced through the use of nitrogen doped nanocrystalline diamond (nNCD) films as an interlayer. The FEE properties of hBNNWs-nNCD heterostructures show a low turn-on field of 15.2 V/μm, a high FEE current density of 1.48 mA/cm(2) and life-time up to a period of 248 min. These values are far superior to those for hBNNWs grown on Si substrates without the nNCD interlayer, which have a turn-on field of 46.6 V/μm with 0.21 mA/cm(2) FEE current density and life-time of 27 min. Cross-sectional TEM investigation reveals that the utilization of the diamond interlayer circumvented the formation of amorphous boron nitride prior to the growth of hexagonal boron nitride. Moreover, incorporation of carbon in hBNNWs improves the conductivity of hBNNWs. Such a unique combination of materials results in efficient electron transport crossing nNCD-to-hBNNWs interface and inside the hBNNWs that results in enhanced field emission of electrons. The prospective application of these materials is manifested by plasma illumination measurements with lower threshold voltage (370 V) and longer life-time, authorizing the role of hBNNWs-nNCD heterostructures in the enhancement of electron emission.

  10. Nanoparticle-enhanced fluorescence emission for non-separation assays of carbohydrates using a boronic acid-alizarin complex.

    Science.gov (United States)

    Li, Qianjin; Kamra, Tripta; Ye, Lei

    2016-03-01

    Addition of crosslinked polymer nanoparticles into a solution of a 3-nitrophenylboronic acid-alizarin complex leads to significant enhancement of fluorescence emission. Using the nanoparticle-enhanced boronic acid-alizarin system has improved greatly the sensitivity and extended the dynamic range of separation-free fluorescence assays for carbohydrates.

  11. Boron-doped graphene quantum dots for selective glucose sensing based on the "abnormal" aggregation-induced photoluminescence enhancement.

    Science.gov (United States)

    Zhang, Li; Zhang, Zhi-Yi; Liang, Ru-Ping; Li, Ya-Hua; Qiu, Jian-Ding

    2014-05-06

    A hydrothermal approach for the cutting of boron-doped graphene (BG) into boron-doped graphene quantum dots (BGQDs) has been proposed. Various characterizations reveal that the boron atoms have been successfully doped into graphene structures with the atomic percentage of 3.45%. The generation of boronic acid groups on the BGQDs surfaces facilitates their application as a new photoluminescence (PL) probe for label free glucose sensing. It is postulated that the reaction of the two cis-diol units in glucose with the two boronic acid groups on the BGQDs surfaces creates structurally rigid BGQDs-glucose aggregates, restricting the intramolecular rotations and thus resulting in a great boost in the PL intensity. The present unusual "aggregation-induced PL increasing" sensing process excludes any saccharide with only one cis-diol unit, as manifested by the high specificity of BGQDs for glucose over its close isomeric cousins fructose, galactose, and mannose. It is believed that the doping of boron can introduce the GQDs to a new kind of surface state and offer great scientific insights to the PL enhancement mechanism with treatment of glucose.

  12. Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases.

    Science.gov (United States)

    Madhav Reddy, K; Guo, J J; Shinoda, Y; Fujita, T; Hirata, A; Singh, J P; McCauley, J W; Chen, M W

    2012-01-01

    Ceramics typically have very high hardness, but low toughness and plasticity. Besides intrinsic brittleness associated with rigid covalent or ionic bonds, porosity and interface phases are the foremost characteristics that lead to their failure at low stress levels in a brittle manner. Here we show that, in contrast to the conventional wisdom that these features are adverse factors in mechanical properties of ceramics, the compression strength, plasticity and toughness of nanocrystalline boron carbide can be noticeably improved by introducing nanoporosity and weak amorphous carbon at grain boundaries. Transmission electron microscopy reveals that the unusual nanosize effect arises from the deformation-induced elimination of nanoporosity mediated by grain boundary sliding with the assistance of the soft grain boundary phases. This study has important implications in developing high-performance ceramics with ultrahigh strength and enhanced plasticity and toughness.

  13. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  14. Enhanced half-metallicity in orientationally misaligned graphene/hexagonal boron nitride lateral heterojunctions

    Science.gov (United States)

    Zeng, Jiang; Chen, Wei; Cui, Ping; Zhang, Dong-Bo; Zhang, Zhenyu

    2016-12-01

    The ever increasing level of control in the fabrication of graphene/hexagonal boron nitride (h -BN) lateral heterostructures makes it promising for material realization of exotic electronic and spintronic properties of graphene. Yet recent first-principles studies have revealed that the pronounced half-metallicity expected for electrically biased freestanding graphene nanoribbons is severely suppressed when the lateral heterostructures are orientationally aligned. By properly tailoring the orientational misalignment between zigzag graphene and chiral h -BN nanoribbons, here we show that the half-metallicity can be substantially enhanced from the aligned case, back to be comparable in magnitude with the freestanding case. In addition, the strain energy accumulation in such misaligned heterojunctions is significantly diminished, favoring physical realization of such structures. The restored half-metallicity is largely attributed to the recovered superexchange interaction between the electrons at the opposite heterojunction interfaces. The present findings may have important implications in the development of graphene-based spintronics.

  15. Strategy for stochastic dose-rate induced enhanced elimination of malignant tumour without dose escalation.

    Science.gov (United States)

    Paul, Subhadip; Roy, Prasun Kumar

    2016-09-01

    The efficacy of radiation therapy, a primary modality of cancer treatment, depends in general upon the total radiation dose administered to the tumour during the course of therapy. Nevertheless, the delivered radiation also irradiates normal tissues and dose escalation procedure often increases the elimination of normal tissue as well. In this article, we have developed theoretical frameworks under the premise of linear-quadratic-linear (LQL) model using stochastic differential equation and Jensen's inequality for exploring the possibility of attending to the two therapeutic performance objectives in contraposition-increasing the elimination of prostate tumour cells and enhancing the relative sparing of normal tissue in fractionated radiation therapy, within a prescribed limit of total radiation dose. Our study predicts that stochastic temporal modulation in radiation dose-rate appreciably enhances prostate tumour cell elimination, without needing dose escalation in radiation therapy. However, constant higher dose-rate can also enhance the elimination of tumour cells. In this context, we have shown that the sparing of normal tissue with stochastic dose-rate is considerably more than the sparing of normal tissue with the equivalent constant higher dose-rate. Further, by contrasting the stochastic dose-rate effects under LQL and linear-quadratic (LQ) models, we have also shown that the LQ model over-estimates stochastic dose-rate effect in tumour and under-estimates the stochastic dose-rate effect in normal tissue. Our study indicates the possibility of utilizing stochastic modulation of radiation dose-rate for designing enhanced radiation therapy protocol for cancer.

  16. Development of a dual phantom technique for measuring the fast neutron component of dose in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Yoshinori, E-mail: yosakura@rri.kyoto-u.ac.jp; Tanaka, Hiroki; Kondo, Natsuko; Kinashi, Yuko; Suzuki, Minoru; Masunaga, Shinichiro; Ono, Koji; Maruhashi, Akira [Kyoto University Research Reactor Institute, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

    2015-11-15

    Purpose: Research and development of various accelerator-based irradiation systems for boron neutron capture therapy (BNCT) is underway throughout the world. Many of these systems are nearing or have started clinical trials. Before the start of treatment with BNCT, the relative biological effectiveness (RBE) for the fast neutrons (over 10 keV) incident to the irradiation field must be estimated. Measurements of RBE are typically performed by biological experiments with a phantom. Although the dose deposition due to secondary gamma rays is dominant, the relative contributions of thermal neutrons (below 0.5 eV) and fast neutrons are virtually equivalent under typical irradiation conditions in a water and/or acrylic phantom. Uniform contributions to the dose deposited from thermal and fast neutrons are based in part on relatively inaccurate dose information for fast neutrons. This study sought to improve the accuracy in the dose estimation for fast neutrons by using two phantoms made of different materials in which the dose components can be separated according to differences in the interaction cross sections. The development of a “dual phantom technique” for measuring the fast neutron component of dose is reported. Methods: One phantom was filled with pure water. The other phantom was filled with a water solution of lithium hydroxide (LiOH) capitalizing on the absorbing characteristics of lithium-6 (Li-6) for thermal neutrons. Monte Carlo simulations were used to determine the ideal mixing ratio of Li-6 in LiOH solution. Changes in the depth dose distributions for each respective dose component along the central beam axis were used to assess the LiOH concentration at the 0, 0.001, 0.01, 0.1, 1, and 10 wt. % levels. Simulations were also performed with the phantom filled with 10 wt. % {sup 6}LiOH solution for 95%-enriched Li-6. A phantom was constructed containing 10 wt. % {sup 6}LiOH solution based on the simulation results. Experimental characterization of the

  17. Enhancing Thermal Conductivity of Hexagonal Boron Nitride Filled Thermoplastics for Thermal Interface Management

    Science.gov (United States)

    Prindl, John

    Hexagonal Boron Nitride has been shown to enhance thermal conductivity in polymer composites more so than conventional ceramic fillers. However, to see a significant increase in thermal conductivity a high loading level of the advanced ceramic is often needed which can have an adverse effect on the mechanical behavior of the composite part. Applications for thermal management using thermal interface materials (TIM) continue to grow with thermoplastic injection molded parts emerging as an area for market growth. There is a growing need for published technical data in this particular area of application. In the current study, the thermal conductivity and mechanical behavior of hexagonal Boron Nitride (hBN) loaded thermoplastic composites is investigated. The main objectives of this work is produce a novel data package which illustrates the effects of hBN, loaded at high concentrations, across several different thermoplastic resins with the ultimate goal being to find a desirable formulation for specific thermal management applications. The desired properties for such applications being high thermal conductivity and high electrical resistivity with a minimal decrease in mechanical properties. Hexagonal BN cooling filler agglomerates were compounded into polypropylene (PP), nylon-6 (PA-6), and thermoplastic elastomer (TPE) via twin-screw extruder at 3 different loading levels. Injection molded samples were produced and characterized to show varying degrees of thermal conductivity and mechanical strength. Results from this research showed that in all cases, the thermal conductivity increased with increasing levels of hBN addition. The largest increases in thermal conductivity were seen in the PA-6 and TPE systems with the possible indication of exceeding the percolation threshold in the TPE system. This is hypothesized to occur due to the preferential migration of hBN to form conduction pathways around the elastomeric domains in the TPE matrix. Though TPE produced

  18. Boron nitride nanosheets as improved and reusable substrates for gold nanoparticles enabled surface enhanced Raman spectroscopy

    KAUST Repository

    Cai, Qiran

    2015-01-01

    Atomically thin boron nitride (BN) nanosheets have been found to be excellent substrates for noble metal particles enabled surface enhanced Raman spectroscopy (SERS), thanks to their good adsorption of aromatic molecules, high thermal stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been synthesized on BN nanosheets using a simple but controllable and reproducible sputtering and annealing method. The size and density of the Au particles can be controlled by sputtering time, current and annealing temperature etc. Under the same sputtering and annealing conditions, the Au particles on BN of different thicknesses show various sizes because the surface diffusion coefficients of Au depend on the thickness of BN. Intriguingly, decorated with similar morphology and distribution of Au particles, BN nanosheets exhibit better Raman enhancements than silicon substrates as well as bulk BN crystals. Additionally, BN nanosheets show no noticeable SERS signal and hence cause no interference to the Raman signal of the analyte. The Au/BN substrates can be reused by heating in air to remove the adsorbed analyte without loss of SERS enhancement. This journal is © the Owner Societies 2015.

  19. TiO2 nanopowder co-doped with iodine and boron to enhance visible-light photocatalytic activity.

    Science.gov (United States)

    Ding, Jianqiang; Yuan, Yali; Xu, Jinsheng; Deng, Jian; Guo, Jianbo

    2009-10-01

    An iodine and boron co-doped TiO2 photocatalyst was prepared by the hydrolyzation-precipitation method. X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS) were applied to characterize the crystalline structure, light absorbing ability, and the chemical state of iodine and boron in the photocatalysts. The results of photocatalytic degradation of methyl orange demonstrated that the I-B-TiO2 catalyst prepared at 400 degrees C for 3 h exhibited the highest photocatalytic activity with a methyl orange degradation ratio of 61% under visible-light (lambda > or = 420 nm) irradiation for 120 min. The characterization results revealed that I-B-TiO2 is in conformity with the anatase TiO2 and that the doping of iodine and boron ions could efficiently inhibit the grain growth. Doped iodine was present in the multivalent forms of 17+, I- and I5+. Doped boron was present as B3+ in an as-prepared sample, forming a possible chemical environment such as B-O-Ti. Overall, the doping of I and B enhanced the ability of TiO2 to absorb visible-light, and it was observed that the photocatalytic activity of I-B-TiO2 was enhanced by the synergistic effect of I and B.

  20. Correlation of clinical outcome to the estimated radiation dose from Boron Neutron Capture Therapy (BNCT)

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M. [Beth Israel Medical Center, NY (United States). Dept. of Radiation Oncology; Coderre, J.A.; Chanana, A.D. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1996-12-31

    A phase I/II trial delivering a single fraction of BNCT using p-Boronophenylalanine-Fructose and epithermal neutrons at the the Brookhaven Medical Research Reactor was initiated in September 1994. The primary endpiont of the study was to evaluate the feasibility and safety of a given BNCT dose. The clinical outcome of the disease was a secondary endpoint of the study. The objective of this paper is to evaluate the correlation of the clinical outcome of patients to the estimated radiation dose from BNCT.

  1. Boron doped g-C3N4 with enhanced photocatalytic UO22+ reduction performance

    Science.gov (United States)

    Lu, Changhai; Chen, Rongyue; Wu, Xi; Fan, Meifeng; Liu, Yunhai; Le, Zhanggao; Jiang, Shujuan; Song, Shaoqing

    2016-01-01

    Tuning the band gap and absorption intensity of visible-light by element doping is an attractive strategy to enhance the photocatalytic activity of semiconductor materials. Here we doped boron into g-C3N4 to construct highly efficient photocatalysts (B-g-C3N4) for the photocatalytic reduction of UO22+. Characterization and photocatalysis tests showed the band gap of B-g-C3N4 was narrowed, and the absorption intensity of visible-light was enhanced with increasing the formed N-B-C (BCN) of B-g-C3N4, which is consistent with the trend of the photocatalytic performance of B-g-C3N4. The optimized B-g-C3N4 photocatalyst with BCN content of 1.01 at.% exhibited excellent removal efficiency of UO22+ and good photocatalytic stability. Therefore, these results may lead to a new strategy for exploring the advanced photocatalysts based on the carbon nanomaterials with abundant BCN for the photocatalytic reduction of U(VI) pollutant.

  2. Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity

    Science.gov (United States)

    Xia, Changlei; Garcia, Andres C.; Shi, Sheldon Q.; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R.; D’Souza, Nandika A.; Nie, Xu

    2016-10-01

    Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m‑1 K‑1, which was 72.3% higher than that (3.600 W m‑1 K‑1) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler’s interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite’s use as an engineered material.

  3. Huge thermal conductivity enhancement in boron nitride – ethylene glycol nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Żyła, Gaweł, E-mail: gzyla@prz.edu.pl [Department of Physics and Medical Engineering, Rzeszow University of Technology, Rzeszow, 35-905 (Poland); Fal, Jacek; Traciak, Julian [Department of Physics and Medical Engineering, Rzeszow University of Technology, Rzeszow, 35-905 (Poland); Gizowska, Magdalena; Perkowski, Krzysztof [Department of Nanotechnology, Institute of Ceramics and Building Materials, Warsaw, 02-676 (Poland)

    2016-09-01

    Paper presents the results of experimental studies on thermophysical properties of boron nitride (BN) plate-like shaped particles in ethylene glycol (EG). Essentially, the studies were focused on the thermal conductivity of suspensions of these particles. Nanofluids were obtained with two-step method (by dispersing BN particles in ethylene glycol) and its’ thermal conductivity was analyzed at various mass concentrations, up to 20 wt. %. Thermal conductivity was measured in temperature range from 293.15 K to 338.15 K with 15 K step. The measurements of thermal conductivity of nanofluids were performed in the system based on a device using the transient line heat source method. Studies have shown that nanofluids’ thermal conductivity increases with increasing fraction of nanoparticles. The results of studies also presented that the thermal conductivity of nanofluids changes very slightly with the increase of temperature. - Highlights: • Huge thermal conductivity enhancement in BN-EG nanofluid was reported. • Thermal conductivity increase very slightly with increasing of the temperature. • Thermal conductivity increase linearly with volume concentration of particles.

  4. Hybrid boron nitride-natural fiber composites for enhanced thermal conductivity.

    Science.gov (United States)

    Xia, Changlei; Garcia, Andres C; Shi, Sheldon Q; Qiu, Ying; Warner, Nathaniel; Wu, Yingji; Cai, Liping; Rizvi, Hussain R; D'Souza, Nandika A; Nie, Xu

    2016-10-05

    Thermal conductivity was dramatically increased after adding natural fiber into hexagonal boron nitride (hBN)/epoxy composites. Although natural fiber does not show high-thermal conductivity itself, this study found that the synergy of natural fiber with hBN could significantly improve thermal conductivity, compared with that solely using hBN. A design of mixtures approach using constant fibers with increasing volume fractions of hBN was examined and compared. The thermal conductivity of the composite containing 43.6% hBN, 26.3% kenaf fiber and 30.1% epoxy reached 6.418 W m(-1) K(-1), which was 72.3% higher than that (3.600 W m(-1) K(-1)) of the 69.0% hBN and 31.0% epoxy composite. Using the scanning electron microscope (SEM) and micro computed tomography (micro-CT), it was observed that the hBN powders were well distributed and ordered on the fiber surfaces enhancing the ceramic filler's interconnection, which may be the reason for the increase in thermal conductivity. Additionally, the results from mechanical and dynamic mechanical tests showed that performances dramatically improved after adding kenaf fibers into the hBN/epoxy composite, potentially benefiting the composite's use as an engineered material.

  5. Monte Carlo study of radiation dose enhancement by gadolinium in megavoltage and high dose rate radiotherapy.

    Directory of Open Access Journals (Sweden)

    Daniel G Zhang

    Full Text Available MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF and conventional flattened 6MV photon beams were used. High dose rate (HDR brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL would be needed.

  6. Monte Carlo study of radiation dose enhancement by gadolinium in megavoltage and high dose rate radiotherapy.

    Science.gov (United States)

    Zhang, Daniel G; Feygelman, Vladimir; Moros, Eduardo G; Latifi, Kujtim; Zhang, Geoffrey G

    2014-01-01

    MRI is often used in tumor localization for radiotherapy treatment planning, with gadolinium (Gd)-containing materials often introduced as a contrast agent. Motexafin gadolinium is a novel radiosensitizer currently being studied in clinical trials. The nanoparticle technologies can target tumors with high concentration of high-Z materials. This Monte Carlo study is the first detailed quantitative investigation of high-Z material Gd-induced dose enhancement in megavoltage external beam photon therapy. BEAMnrc, a radiotherapy Monte Carlo simulation package, was used to calculate dose enhancement as a function of Gd concentration. Published phase space files for the TrueBeam flattening filter free (FFF) and conventional flattened 6MV photon beams were used. High dose rate (HDR) brachytherapy with Ir-192 source was also investigated as a reference. The energy spectra difference caused a dose enhancement difference between the two beams. Since the Ir-192 photons have lower energy yet, the photoelectric effect in the presence of Gd leads to even higher dose enhancement in HDR. At depth of 1.8 cm, the percent mean dose enhancement for the FFF beam was 0.38±0.12, 1.39±0.21, 2.51±0.34, 3.59±0.26, and 4.59±0.34 for Gd concentrations of 1, 5, 10, 15, and 20 mg/mL, respectively. The corresponding values for the flattened beam were 0.09±0.14, 0.50±0.28, 1.19±0.29, 1.68±0.39, and 2.34±0.24. For Ir-192 with direct contact, the enhanced were 0.50±0.14, 2.79±0.17, 5.49±0.12, 8.19±0.14, and 10.80±0.13. Gd-containing materials used in MRI as contrast agents can also potentially serve as radiosensitizers in radiotherapy. This study demonstrates that Gd can be used to enhance radiation dose in target volumes not only in HDR brachytherapy, but also in 6 MV FFF external beam radiotherapy, but higher than the currently used clinical concentration (>5 mg/mL) would be needed.

  7. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  8. Enhancement of neutron radiation dose by the addition of sulphur-33 atoms

    Energy Technology Data Exchange (ETDEWEB)

    Porras, I [Departamento de Fisica Atomica, Molecular y Nuclear (formerly Fisica Moderna), Facultad de Ciencias, Universidad de Granada, E-18071 Granada (Spain)], E-mail: porras@ugr.es

    2008-04-07

    The use of neutrons in radiotherapy allows the possibility of producing nuclear reactions in a specific target inserted in the medium. {sup 10}B is being used to induce reactions (n, {alpha}), a technique called boron neutron capture therapy. I have studied the possibility of inducing a similar reaction using the nucleus of {sup 33}S, for which the reaction cross section presents resonances for keV neutrons, the highest peak occurring at 13.5 keV. Here shown, by means of Monte Carlo simulation of point-like sources of neutrons in this energy range, is an enhancement effect on the absorbed dose in water by the addition of {sup 33}S atoms. In addition to this, as the range of the alpha particle is of the order of a mammalian cell size, the energy deposition via this reaction results mainly inside the cells adjacent to the interaction site. The main conclusion of the present work is that the insertion of these sulphur atoms in tumoral cells would enhance the effect of neutron irradiation in the keV range. (letter to the editor)

  9. Measurement of gold nanofilm dose enhancement using unlaminated radiochromic film

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, Joseph T., E-mail: rakowski@karmanos.org; Snyder, Michael G.; Hillman, Yair [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 (United States); Laha, Suvra S.; Lawes, Gavin [Department of Physics, Wayne State University, Detroit, Michigan 48201 (United States); Buczek, Matthew G. [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 and MidMichigan Health, Midland, Michigan 48670 (United States); Tucker, Mark A. [Department of Radiation Oncology, School of Medicine, Wayne State University, Detroit, Michigan 48201 and Missouri Cancer Associates, Columbia, Missouri 65202 (United States); Liu, Fangchao; Mao, Guangzhao [Department of Chemical Engineering and Materials Science, College of Engineering, Wayne State University, Detroit, Michigan 48201 (United States)

    2015-10-15

    Purpose: Bombarding high-Z material with x-ray radiation releases Auger electrons and Coster–Kronig electrons, along with deeper penetrating fluorescent x-rays and photoelectrons. The Auger and Coster–Kronig electron penetration distance is on the order of nanometers to micrometers in water or tissue, creating a large dose enhancement accompanied by a RBE greater than 1 at the cellular level. The authors’ aim is to measure the gold nanofilm dose enhancement factor (DEF) at the cellular level with unlaminated radiochromic film via primary 50 kVp tungsten x-ray spectrum interaction, similar to an electronic brachytherapy spectrum. Methods: Unlaminated Gafchromic{sup ®} EBT2 film and Monte Carlo modeling were combined to derive DEF models. Gold film of thickness 23.1 ±  4.3 nm and surface roughness of 1.2 ± 0.2 nm was placed in contact with unlaminated radiochromic film in a downstream orientation and exposed to a 50 kVp tungsten bremsstrahlung, mean energy 19.2 keV. Film response correction factors were derived by Monte Carlo modeling of electron energy deposition in the film’s active layer, and by measuring film energy dependence from 4.5 keV to 50 kVp. Results: The measured DEF within a 13.6 μm thick water layer was 0.29 with a mean dose of 94 ± 9.4 cGy from Au emissions and 324 ± 32.4 cGy from the 50 kVp primary beam. Monte Carlo derived correction factors allowed determination of Au contributed dose in shallower depths at 0.25 μm intervals. Maximum DEF of 18.31 was found in the first 0.25 μm water depth. Conclusions: Dose enhancement from Au nanofilm can be measured at the cellular level using unlaminated radiochromic film. Complementing the measured dose value with Monte Carlo calculations allows estimation of dose enhancement at depth increments within the cellular range.

  10. Enhanced boron adsorption onto synthesized MgO nanosheets by ultrasonic method.

    Science.gov (United States)

    Li, Ping; Liu, Chuang; Zhang, Li; Zheng, Shili; Zhang, Yi

    2017-01-01

    MgO nanosheets with high adsorption performance were fabricated by an ultrasonic method. It was revealed that, nest-like MgO was formed from the magnesium salt solution precipitation and further calcination. Then the nest-like MgO was exfoliated by ultrasonic waves to obtain MgO nanosheets with approximately a lateral of 200-600nm and a thickness of 10nm. Adjusting the ultrasonic time and power, the specific surface areas of MgO nanosheets could be tuned in a range of 79-168m(2)/g. The synthesized MgO nanosheets were used as adsorbents to remove boron from aqueous solution, and the maximum boron adsorption capacity of these MgO nanosheets reached 87mgg(-1). The high uptake capability of the MgO nanosheets makes it potentially adsorbent for the removal of boron from wastewaters.

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

    Science.gov (United States)

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

    2016-01-01

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

  12. Using a mobile transparent plastic-lead-boron shielding barrier to reduce radiation dose exposure in the work place

    Energy Technology Data Exchange (ETDEWEB)

    Parra, S A; Mecozzi, J M

    2001-01-11

    Moveable radiation shielding barriers made of plastic material containing lead and boron can be used to reduce radiation exposure near the work place. Personnel can maneuver and position the transparent radiation shielding barriers anywhere within the work place. The lead in the shielding barrier provides an effective shielding material against radiation exposure (approximately a 1.0 mm lead equivalent protection) while the boron in the shielding barrier provides neutron absorption to reduce the moderation/reflection effects of the shielding materials (approximately a 2% {Delta}k/k reduction).

  13. Evaluation of the microscopic dose enhancement for nanoparticle-enhanced Auger therapy

    Science.gov (United States)

    Sung, Wonmo; Jung, Seongmoon; Ye, Sung-Joon

    2016-11-01

    The aim of this study is to investigate the dosimetric characteristics of nanoparticle-enhanced Auger therapy. Monte Carlo (MC) simulations were performed to assess electron energy spectra and dose enhancement distributions around a nanoparticle. In the simulations, two types of nanoparticle structures were considered: nanoshell and nanosphere, both of which were assumed to be made of one of five elements (Fe, Ag, Gd, Au, and Pt) in various sizes (2-100 nm). Auger-electron emitting radionuclides (I-125, In-111, and Tc-99m) were simulated within a nanoshell or on the surface of a nanosphere. For the most promising combination of Au and I-125, the maximum dose enhancement was up to 1.3 and 3.6 for the nanoshell and the nanosphere, respectively. The dose enhancement regions were restricted within 20-100 nm and 0-30 nm distances from the surface of Au nanoshell and nanosphere, respectively. The dose enhancement distributions varied with sizes of nanoparticles, nano-elements, and radionuclides and thus should be carefully taken into account for biological modeling. If the nanoparticles are accumulated in close proximity to the biological target, this new type of treatment can deliver an enhanced microscopic dose to the target (e.g. DNA). Therefore, we conclude that Auger therapy combined with nanoparticles could have the potential to provide a better therapeutic effect than conventional Auger therapy alone.

  14. BAD-lectins: boronic acid-decorated lectins with enhanced binding affinity for the selective enrichment of glycoproteins.

    Science.gov (United States)

    Lu, Ying-Wei; Chien, Chih-Wei; Lin, Po-Chiao; Huang, Li-De; Chen, Chang-Yang; Wu, Sz-Wei; Han, Chia-Li; Khoo, Kay-Hooi; Lin, Chun-Cheng; Chen, Yu-Ju

    2013-09-03

    The weak and variable binding affinities exhibited by lectin-carbohydrate interactions have often compromised the practical utility of lectin in capturing glycoproteins for glycoproteomic applications. We report here the development and applications of a new type of hybrid biomaterial, namely a boronic acid-decorated lectin (BAD-lectin), for efficient bifunctional glycoprotein labeling and enrichment. Our binding studies showed an enhanced affinity by BAD-lectin, likely to be mediated via the formation of boronate ester linkages between the lectin and glycan subsequent to the initial recognition process and thus preserving its glycan-specificity. Moreover, when attached to magnetic nanoparticles (BAD-lectin@MNPs), 2 to 60-fold improvement on detection sensitivity and enrichment efficiency for specific glycoproteins was observed over the independent use of either lectin or BA. Tested at the level of whole cell lysates for glycoproteomic applications, three different types of BAD-lectin@MNPs exhibited excellent specificities with only 6% overlapping among the 295 N-linked glycopeptides identified. As many as 236 N-linked glycopeptides (80%) were uniquely identified by one of the BAD-lectin@MNPs. These results indicated that the enhanced glycan-selective recognition and binding affinity of BAD-lectin@MNPs will facilitate a complementary identification of the under-explored glycoproteome.

  15. Chronic boron exposure and human semen parameters.

    Science.gov (United States)

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

    2010-04-01

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

  16. Enhancement of the power factor in two-phase silicon-boron nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Narducci, Dario; Lorenzi, Bruno [Department of Materials Science, University of Milano Bicocca, Milan (Italy); Zianni, Xanthippe [Department of Aircraft Technologies, Technological Educational Institution of Sterea Ellada, Psachna (Greece); Department of Microelectronics, IAMPPNM, NCSR Demokritos, Athens (Greece); Neophytou, Neophytos [Institute for Microelectronics, TUV, Vienna (Austria); School of Engineering, University of Warwick, Coventry (United Kingdom); Frabboni, Stefano [Department of FIM, University of Modena and Reggio Emilia, Modena (Italy); CNR-Institute of Nanoscience-S3, Modena (Italy); Gazzadi, Gian Carlo [CNR-Institute of Nanoscience-S3, Modena (Italy); Roncaglia, Alberto; Suriano, Francesco [IMM-CNR, Bologna (Italy)

    2014-06-15

    In previous publications it was shown that the precipitation of silicon boride around grain boundaries may lead to an increase of the power factor in nanocrystalline silicon. Such an effect was further explained by computational analyses showing that the formation of an interphase at the grain boundaries along with high boron densities can actually lead to a concurrent increase of the electrical conductivity σ and of the Seebeck coefficient S. In this communication we report recent evidence of the key elements ruling such an unexpected effect. Nanocrystalline silicon films deposited onto a variety of substrates were doped to nominal boron densities in excess of 10{sup 20} cm{sup -3} and were annealed up to 1000 C to promote boride precipitation. Thermoelectric properties were measured and compared with their microstructure. A concurrent increase of σ and S with the carrier density was found only upon formation of an interphase. Its dependency on the film microstructure and on the deposition and processing conditions will be discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Enhancement of toughness and wear resistance in boron nitride nanoplatelet (BNNP) reinforced Si3N4 nanocomposites

    Science.gov (United States)

    Lee, Bin; Lee, Dongju; Lee, Jun Ho; Ryu, Ho Jin; Hong, Soon Hyung

    2016-06-01

    Ceramics have superior hardness, strength and corrosion resistance, but are also associated with poor toughness. Here, we propose the boron nitride nanoplatelet (BNNP) as a novel toughening reinforcement component to ceramics with outstanding mechanical properties and high-temperature stability. We used a planetary ball-milling process to exfoliate BNNPs in a scalable manner and functionalizes them with polystyrene sulfonate. Non-covalently functionalized BNNPs were homogeneously dispersed with Si3N4 powders using a surfactant and then consolidated by hot pressing. The fracture toughness of the BNNP/Si3N4 nanocomposite increased by as much as 24.7% with 2 vol.% of BNNPs. Furthermore, BNNPs enhanced strength (9.4%) and the tribological properties (26.7%) of the ceramic matrix. Microstructural analyzes have shown that the toughening mechanisms are combinations of the pull-out, crack bridging, branching and blunting mechanisms.

  18. Exploring the effect of boron and tantalum codoping on the enhanced photocatalytic activity of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yinyan, E-mail: ygong2007@163.com; Fu, Chengxin; Ting, Lv; Chenu, Jingru; Zhao, Qinger; Li, Can

    2015-10-01

    Graphical abstract: B and Ta codoped sample was prepared by a sol–gel method, which exhibits the best photocatalytic performance on degradation of methylene blue solution under a simulated solar light source in comparison with undoped and singly doped TiO{sub 2} nanocrystals. The enhancement was tentatively attributed to: (1) the increase of free electron concentrations by substituting Ti{sup 4+} with Ta{sup 5+} species, as well as the prolonged carrier lifetime due to the complex structures formed by Bint, Ta{sup 5+}, and doping-induced defects; (2) redshift of optical absorption edge due to the presence of B species at interstitial sites, and (3) reduction of average crystallite size. - Highlights: • Boron and tantalum codoped TiO{sub 2} photocatalyts were prepared by a sol–gel method. • XRD and Raman measurements confirmed that all the TiO{sub 2} nanocyrstals are anatase structure. • Ta in the form of Ta{sup 5+} and interstitial B and substitutional B are detected by XPS observations. • (B, Ta)-codoped sample has the best efficiency compared to pure and singly doped catalysts. - Abstract: Aiming to improve the photocatalytic activity, boron and tantalum co-doped TiO{sub 2} nanocrystals were prepared by a sol–gel method. Pure and doped titania samples were characterized by X-ray diffraction (XRD) measurements, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy. The results revealed that all the samples have highly crystalline anatase structure, and no any other second phase was observed. It is found that the incorporation of dopants inhibits the growth of TiO{sub 2} nanocrystal. Moreover, XPS observations showed that Ta are in the form of Ta{sup 5+} while the majority of B species are present at interstitial sites. Finally, photocatalytic activities of all the samples were evaluated by degradation of methylene blue (MB) solutions under simulated solar light irradiation. Ta-doped and (B, Ta

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

    Energy Technology Data Exchange (ETDEWEB)

    Ipus, J. J.; Blazquez, J. S.; Franco, V.; Conde, A. [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, 41080 Sevilla (Spain)

    2013-05-07

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

  20. Fabrication and characterization of composite TiO{sub 2} nanotubes/boron-doped diamond electrodes towards enhanced supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Sobaszek, M. [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland); Siuzdak, K.; Sawczak, M. [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk (Poland); Ryl, J. [Department of Electrochemistry, Corrosion and Material Engineering, Faculty of Chemistry, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdańsk (Poland)

    2016-02-29

    The composite TiO{sub 2} nanotubes/boron-doped diamond electrodes were deposited using Microwave Plasma Enhanced Chemical Vapor Deposition resulting in the improved electrochemical performance. This composite electrode can deliver high specific capacitance of 7.46 mF cm{sup −2} comparing to boron-doped diamond (BDD) deposited onto flat Ti plate (0.11 mF cm{sup −2}).The morphology and composition of composite electrode were characterized by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) techniques. According to XPS and Raman analyses, the structure of TiO{sub 2} was greatly changed during Chemical Vapor Deposition process: formation of Ti{sup 3+} sites, partial anatase to rutile transformation and titanium carbide phase formation. This effect is attributed to the simultaneous presence of activated hydrogen and carbon in the plasma leading to enhanced dehydration of NTs (nanotubes) followed by carbon bonding. The enhanced capacitive effect of TiO{sub 2} NT/BDD could be recognized as: (1) the unique synergistic morphology of NTs and BDD providing more efficient conducting pathway for the diffusion of ions and (2) partial decomposition of NTs and transformation towards to TiC and Ti{sub 2}O{sub 3} fractions. Finally, highly ordered titania nanotubes produced via simply, quick and controllable method — anodization, could act as promising substrate for conductive BDD layer deposition and further application of such composites for supercapacitor construction. - Highlights: • The TiO{sub 2} nanotube (NT)/diamond electrode delivers capacitance of 7.46 mF cm{sup −2}. • The NTs are not affected by diamond growth process and keep their pristine shape. • The BDD overlayer fully encapsulates TiO{sub 2} NTs exhibiting typical columnar growth. • The activated hydrogen and carbon in the plasma lead to enhanced dehydration of NTs. • The presence of TiC and Ti{sub 2}O{sub 3} fractions introducing additional capacitance.

  1. Engineering the interface characteristics on the enhancement of field electron emission properties of vertically aligned hexagonal boron nitride nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Sankaran, K.J.; Hoang, D.Q.; Drijkoningen, S.; Pobedinskas, P.; Haenen, K. [Institute for Materials Research (IMO), Hasselt University, Diepenbeek (Belgium); IMOMEC, IMEC vzw, Diepenbeek (Belgium); Srinivasu, K.; Leou, K.C. [Department of Engineering and System Science, National Tsing Hua University, Hsinchu (China); Korneychuk, S.; Turner, S.; Verbeeck, J. [Electron Microscopy for Materials Science (EMAT), University of Antwerp (Belgium); Lin, I.N. [Department of Physics, Tamkang University, Tamsui (China)

    2016-10-15

    Utilization of Au and nanocrystalline diamond (NCD) as interlayers noticeably modifies the microstructure and field electron emission (FEE) properties of hexagonal boron nitride nanowalls (hBNNWs) grown on Si substrates. The FEE properties of hBNNWs on Au could be turned on at a low turn-on field of 14.3 V μm{sup -1}, attaining FEE current density of 2.58 mA cm{sup -2} and life-time stability of 105 min. Transmission electron microscopy reveals that the Au-interlayer nucleates the hBN directly, preventing the formation of amorphous boron nitride (aBN) in the interface, resulting in enhanced FEE properties. But Au forms as droplets on the Si substrate forming again aBN at the interface. Conversely, hBNNWs on NCD shows superior in life-time stability of 287 min although it possesses inferior FEE properties in terms of larger turn-on field and lower FEE current density as compared to that of hBNNWs-Au. The uniform and continuous NCD film on Si also circumvents the formation of aBN phases and allows hBN to grow directly on NCD. Incorporation of carbon in hBNNWs from the NCD-interlayer improves the conductivity of hBNNWs, which assists in transporting the electrons efficiently from NCD to hBNNWs that results in better field emission of electrons with high life-time stability. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Synthesis of thin films in boron-carbon-nitrogen ternary system by microwave plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Kukreja, Ratandeep Singh

    The Boron Carbon Nitorgen (B-C-N) ternary system includes materials with exceptional properties such as wide band gap, excellent thermal conductivity, high bulk modulus, extreme hardness and transparency in the optical and UV range that find application in most fields ranging from micro-electronics, bio-sensors, and cutting tools to materials for space age technology. Interesting materials that belong to the B-C-N ternary system include Carbon nano-tubes, Boron Carbide, Boron Carbon Nitride (B-CN), hexagonal Boron Nitride ( h-BN), cubic Boron Nitride (c-BN), Diamond and beta Carbon Nitride (beta-C3N4). Synthesis of these materials requires precisely controlled and energetically favorable conditions. Chemical vapor deposition is widely used technique for deposition of thin films of ceramics, metals and metal-organic compounds. Microwave plasma enhanced chemical vapor deposition (MPECVD) is especially interesting because of its ability to deposit materials that are meta-stable under the deposition conditions, for e.g. diamond. In the present study, attempt has been made to synthesize beta-carbon nitride (beta-C3N4) and cubic-Boron Nitride (c-BN) thin films by MPECVD. Also included is the investigation of dependence of residual stress and thermal conductivity of the diamond thin films, deposited by MPECVD, on substrate pre-treatment and deposition temperature. Si incorporated CNx thin films are synthesized and characterized while attempting to deposit beta-C3N4 thin films on Si substrates using Methane (CH4), Nitrogen (N2), and Hydrogen (H2). It is shown that the composition and morphology of Si incorporated CNx thin film can be tailored by controlling the sequence of introduction of the precursor gases in the plasma chamber. Greater than 100mum size hexagonal crystals of N-Si-C are deposited when Nitrogen precursor is introduced first while agglomerates of nano-meter range graphitic needles of C-Si-N are deposited when Carbon precursor is introduced first in the

  3. Doses de boro e água residuária na produção do girassol Levels of boron and wastewater in production of sunflower

    Directory of Open Access Journals (Sweden)

    José Amilton Santos Junior

    2011-12-01

    Full Text Available A disponibilidade hídrica de qualidade tem se tornado em todo o mundo, um dos principais entraves à expansão das fronteiras agrícolas. Dentro deste contexto o presente trabalho teve como objetivo avaliar os efeitos de doses de boro e da irrigação com dois tipos de água, residuária e de abastecimento, nos componentes de produção do girassol (Helianthus annuus L. cv. EMBRAPA 122/V-2000. A pesquisa foi realizada em ambiente protegido da Universidade Federal de Campina Grande, em delineamento em blocos casualizados, analisados em esquema fatorial 5 x 2 sendo cinco doses de boro (0 - testemunha; 1,0; 2,0; 3,0 e 4,0 mg L-1 combinados com dois tipos de água de irrigação (R - residuária e AB - abastecimento, com três repetições. A análise estatística compreendeu análises de variância (teste F e as médias foram comparadas pelo teste de Tukey para comparar os fatores qualitativos em 0,05 de probabilidade. Verificou-se que as doses de boro e tipos de água utilizados não influenciaram nenhuma variável ligada à produção de aquênios; no entanto, a irrigação com água residuária influenciou positivamente as variáveis fitomassa fresca e seca das folhas, do caule e da parte aérea, todas ligadas à produção de forragem.The availability of water of quality has become worldwide, a major constraint to expanding agricultural frontiers. Within this context, this study aimed to evaluate the effects of boron doses and irrigation with two types of water, wastewater and municipal supply water, on yield components of sunflower (Helianthus annuus L. cv. EMBRAPA 122/V-2000. The study was conducted in a greenhouse at the Federal University of Campina Grande, in a randomized block design, analyzed in a 5 x 2 factorial with five B of boron (0; 1.0; 2.0; 3.0 and 4.0 mg L-1 combined with two types of irrigation water (R - wastewater and AB - municipal supply water with three replications. Statistical analysis consisted of analysis of variance

  4. Polyethyleneimine-functionalized boron nitride nanospheres as efficient carriers for enhancing the immunostimulatory effect of CpG oligodeoxynucleotides

    Directory of Open Access Journals (Sweden)

    Zhang HJ

    2015-08-01

    Full Text Available Huijie Zhang,1 Shini Feng,1 Ting Yan,1 Chunyi Zhi,2 Xiao-Dong Gao,1 Nobutaka Hanagata3,41The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, People’s Republic of China; 2Department of Physics and Materials Science, City University of Hong Kong, Kowlong, Hong Kong SAR, People’s Republic of China; 3Biomaterials Unit, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Ibaraki, Japan; 4Nanotechnology Innovation Station, National Institute for Materials Science, Ibaraki, JapanAbstract: CpG oligodeoxynucleotides (ODNs stimulate innate and adaptive immune responses. Thus, these molecules are promising therapeutic agents and vaccine adjuvants against various diseases. In this study, we developed a novel CpG ODNs delivery system based on polyethyleneimine (PEI-functionalized boron nitride nanospheres (BNNS. PEI was coated on the surface of BNNS via electrostatic interactions. The prepared BNNS–PEI complexes had positive zeta potential and exhibited enhanced dispersity and stability in aqueous solution. In vitro cytotoxicity assays revealed that the BNNS–PEI complexes with concentrations up to 100 µg/mL exhibited no obvious cytotoxicity. Furthermore, the positively charged surface of the BNNS–PEI complexes greatly improved the loading capacity and cellular uptake efficiency of CpG ODNs. Class B CpG ODNs loaded on the BNNS–PEI complexes enhanced the production of interleukin-6 and tumor necrosis factor-α from peripheral blood mononuclear cells compared with CpG ODNs directly loaded on BNNS. Contrary to the free CpG ODNs or CpG ODNs directly loaded on BNNS, class B CpG ODNs loaded on the BNNS–PEI complexes induced interferon-α simultaneously. PEI coating may have changed the physical form of class B CpG ODNs on BNNS, which further affected their interaction with Toll-like receptor 9 and induced interferon

  5. Gamma/neutron dose evaluation using Fricke gel and alanine gel dosimeters to be applied in boron neutron capture therapy.

    Science.gov (United States)

    Mangueira, T F; Silva, C F; Coelho, P R P; Campos, L L

    2010-01-01

    Gel dosimetry has been studied mainly for medical applications. The radiation induced ferric ions concentration can be measured by different techniques to be related with the absorbed dose. Aiming to assess gamma/thermal neutrons dose from research reactors, Fricke gel and alanine gel solutions produced at IPEN using 300 bloom gelatin were mixed with Na(2)B(4)O(7) salt, and the mixtures were irradiated at the beam hole #3 of the IEA-R1 research reactor, (BH#3) adapted to BNCT studies, and the dose-response was evaluated using spectrophotometry technique.

  6. Neutron-photon mixed field dosimetry by TLD-700 glow curve analysis and its implementation in dose monitoring for Boron Neutron Capture Therapy (BNCT) treatments

    Energy Technology Data Exchange (ETDEWEB)

    Boggio, E. F.; Longhino, J. M. [Centro Atomico Bariloche, Departamento de Fisica de Reactores y Radiaciones / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina); Andres, P. A., E-mail: efboggio@cab.cnea.gov.ar [Centro Atomico Bariloche, Division Proteccion Radiologica / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina)

    2015-10-15

    BNCT is a cancerous cells selective, non-conventional radiotherapy modality to treat malignant tumors such as glioblastoma, melanoma and recurrent head and neck cancer. It consists of a two-step procedure: first, the patient is injected with a tumor localizing drug containing a non-radioactive isotope (Boron-10) with high slow neutron capture cross-section. In a second step, the patient is irradiated with neutrons, which are absorbed by the Boron-10 agent with the subsequently nuclear reaction B- 10(n,a)Li-7, thereby resulting in dose at cellular level due to the high-Let particles. The neutron fields suitable for BNCT are characterized by high neutron fluxes and low gamma dose. Determination of each component is not an easy task, especially when the volume of measurement is quite small or inaccessible for a miniature ionization chamber, for example. A method of measuring the photon and slow neutron dose(mainly by N-14 and B-10) from the glow curve (GC) analysis of a single {sup 7}LiF thermoluminescence detector is evaluated. This method was suggested by the group headed by Dr. Grazia Gambarini. The dosemeters used were TLD-600 ({sup 6}LiF:Mg,Ti with 95.6% {sup 6}Li) and TLD-700 ({sup 7}LiF:Mg,Ti with 99.9% {sup 7}LiF) from Harshaw. Photon dose measurement using the GC analysis method with TLD-700 in mixed fields requires the relation of the two main peaks of a TLD-600 GC shape obtained from an exposition to the same neutron field, and a photon calibrated GC with TLD-700. The requirements for slow neutron dose measurements are similar. In order to properly apply the GC analysis method at the Ra-6 Research Reactor BNCT facility, measurements were carried out in a standard water phantom, fully characterized on the BNCT beam by conventional techniques (activation detectors and paired ionization chambers technique). Next, the method was implemented in whole body dose monitoring of a patient undergoing a BNCT treatment, using a Bo MAb (Bottle Manikin Absorption) phantom

  7. Large-scale synthesis of uniform hexagonal boron nitride films by plasma-enhanced atomic layer deposition

    Science.gov (United States)

    Park, Hamin; Kim, Tae Keun; Cho, Sung Woo; Jang, Hong Seok; Lee, Sang Ick; Choi, Sung-Yool

    2017-01-01

    Hexagonal boron nitride (h-BN) has been previously manufactured using mechanical exfoliation and chemical vapor deposition methods, which make the large-scale synthesis of uniform h-BN very challenging. In this study, we produced highly uniform and scalable h-BN films by plasma-enhanced atomic layer deposition, which were characterized by various techniques including atomic force microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The film composition studied by X-ray photoelectron spectroscopy and Auger electron spectroscopy corresponded to a B:N stoichiometric ratio close to 1:1, and the band-gap value (5.65 eV) obtained by electron energy loss spectroscopy was consistent with the dielectric properties. The h-BN-containing capacitors were characterized by highly uniform properties, a reasonable dielectric constant (3), and low leakage current density, while graphene on h-BN substrates exhibited enhanced electrical performance such as the high carrier mobility and neutral Dirac voltage, which resulted from the low density of charged impurities on the h-BN surface.

  8. Oxidation of Silicon and Boron in Boron Containing Molten Iron

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new process of directly smelting boron steel from boron-containing pig iron has been established. The starting material boron-containing pig iron was obtained from ludwigite ore, which is very abundant in the eastern area of Liaoning Province of China. The experiment was performed in a medium-frequency induction furnace, and Fe2O3 powder was used as the oxidizing agent. The effects of temperature, addition of Fe2O3, basicity, stirring, and composition of melt on the oxidation of silicon and boron were investigated respectively. The results showed that silicon and boron were oxidized simultaneously and their oxidation ratio exceeded 90% at 1 400 ℃. The favorable oxidation temperature of silicon was about 1 300-1 350 C. High oxygen potential of slag and strong stirring enhanced the oxidation of silicon and boron.

  9. Evaluation of absorbed effective dose and treatment conditions for a brain tumor outside of the head phantom center in treatment by Boron Neutron Capture Therapy Using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Samira Mirzaiee

    2016-04-01

    (including 252Cf source, moderator, refelector and neutron and photon filters was simulated. A spherical-shaped tumor was considered outside of the phantom center. The head phantom consists of three parts of the skin, skull and brain. The simulation was done by the MCNPX 2.6.0 computational code. In this simulation, the tumor with a radius of 1.5 cm at a depth of 2 cm inside the brain was considered. Results: Tumor treatment was investigated with different boron concentrations in the head phantom. The maximum dose is approximately 0.055 Sv/hr, and is related to the conditions that Boron is not absorbed in healthy tissue. The absorbed dose amount of the epithermal neutrons, under the conditions that Boron is not absorbed in healthy tissue, at the entrance of the skull and in brain tissue extremily drops, and gradually decreases. Conclusion: The calculations showed when a patient receives radiation about 5 minutes, the received dose equals approximately 4.6 mSv.Under these treatment conditions, the whole body equivalent dose  does not exceed 5 mSv per year.

  10. Preparation of Poly(p-phenylene sulfi de)/Carbon Composites with Enhanced Thermal Conductivity and Electrical Insulativity via Hybrids of Boron Nitride and Carbon Fillers

    Institute of Scientific and Technical Information of China (English)

    WU Jieli; WANG Jinwen; CHEN Feng

    2015-01-01

    The present work enhanced the thermal conductivity of poly(p-phenylene sulfi de)/expanded graphites and poly(p-phenylene sulfi de)/carbon nanotubes, by incorporating composites with hexagonal boron nitride, which simultaneously succeeded in raising the electrical conductivity of the systems. A two-step mechanical processing method which includes rotating solid-state premixing and inner mixing was adopted to improve dispersion of the hybrids, contributing to the formation of an interspered thermal conductive network. Similar synergic effect in thermal conductivity enhancement was discovered in the hybrid systems regardless of the dimension difference between the two carbonfi llers. Such is postulated to be the one satisfying advantage generated by the afore-mentioned network; the other is the insulativity of the hybrid systems given by the effective blockage of hexagonal boron nitride as an insulating material in our network.

  11. High-dose gadolinium-enhanced MRI for diagnosis of meningeal metastases

    Energy Technology Data Exchange (ETDEWEB)

    Kallmes, D.F. [Department of Radiology, Box 170, University of Virginia Health Sciences Center, Charlottesville, VA 22908 (United States); Gray, L. [Department of Radiology, Duke University Medical Center, Durham, NC (United States); Glass, J.P. [Department of Medicine, Veterans Administration Hospital, Gainesville, Florida (United States)

    1998-01-01

    We compared high-dose (0.3 mmol/kg) and standard-dose (0.1 mmol/kg) gadolinium-enhanced MRI for diagnosis of meningeal metastases in 12 patients with suspected meningeal metastases. They were imaged with both standard-dose and high-dose gadolinium. All patients with abnormal meningeal enhancement underwent at least one lumbar puncture for cerebrospinal fluid (CSF) cytology, while patients with normal meningeal enhancement were followed clinically. All patients with negative CSF cytology also were followed clinically. A single observer reviewed all the images, with specific attention to the enhancement pattern of the meninges. Abnormal leptomeningeal enhancement was present in three cases, and abnormal pachymeningeal enhancement in three other patients. All of these patients had abnormal CSF analyses. In two of the three cases of abnormal leptomeningeal enhancement the disease was more evident on high-dose than on standard-dose imaging; in one case the abnormal enhancement was visible only on high-dose imaging. In one of the three cases with abnormal pachymeningeal enhancement, the disease was evident prospectively only with high-dose imaging. (orig.) With 3 figs., 10 refs.

  12. Largely enhanced dielectric properties of carbon nanotubes/polyvinylidene fluoride binary nanocomposites by loading a few boron nitride nanosheets

    Science.gov (United States)

    Yang, Minhao; Zhao, Hang; He, Delong; Bai, Jinbo

    2016-08-01

    The ternary nanocomposites of boron nitride nanosheets (BNNSs)/carbon nanotubes (CNTs)/polyvinylidene fluoride (PVDF) are fabricated via a combination of solution casting and extrusion-injection processes. The effects of BNNSs on the electrical conductivity, dielectric behavior, and microstructure changes of CNTs/PVDF binary nanocomposites are systematically investigated. A low percolation value (fc) for the CNTs/PVDF binary system is obtained due to the integration of solution and melting blending procedures. Two kinds of CNTs/PVDF binary systems with various CNTs contents (fCNTs) as the matrix are discussed. The results reveal that compared with CNTs/PVDF binary systems at the same fCNTs, the ternary BNNSs/CNTs/PVDF nanocomposites exhibit largely enhanced dielectric properties due to the improvement of the CNTs dispersion state and the conductive network. The dielectric constant of CNTs/PVDF binary nanocomposite with 6 vol. % CNTs (fCNTs fc), it displays a 43.32% improvement from 1325 to 1899 after the addition of 3 vol. % BNNSs. The presence of BNNSs facilitates the formation of the denser conductive network. Meanwhile, the ternary BNNSs/CNTs/PVDF systems exhibit a low dielectric loss. The adjustable dielectric properties could be obtained by employing the ternary systems due to the microstructure changes of nanocomposites.

  13. Feasibility evaluation of neutron capture therapy for hepatocellular carcinoma using selective enhancement of boron accumulation in tumour with intra-arterial administration of boron-entrapped water-in-oil-in-water emulsion

    Energy Technology Data Exchange (ETDEWEB)

    Yanagie, Hironobu, E-mail: yanagie@n.t.u-tokyo.ac.jp [Dept of Nuclear Engineering and Management, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)] [Cooperative Unit of Medicine and Engineering, University of Tokyo Hospital, Tokyo (Japan); Kumada, Hiroaki [Proton Medical Research Center, University of Tsukuba, Ibaraki (Japan); Nakamura, Takemi [Japan Atomic Energy Research Institute, Ibaraki (Japan); Higashi, Syushi [Dept of Surgery, Ebihara Memorial Hospital, Miyazaki (Japan)] [Kyushu Industrial Sources Foundation, Miyazaki (Japan); Ikushima, Ichiro [Dept of Radiology, Miyakonojyo Metropolitan Hospital, Miyazaki (Japan); Morishita, Yasuyuki [Dept of Human and Molecular Pathology, Graduate School of Medicine, University of Tokyo, Tokyo (Japan); Shinohara, Atsuko [Dept of Humanities, Graduate School of Seisen University, Tokyo (Japan); Fijihara, Mitsuteru [SPG Techno Ltd. Co., Miyazaki (Japan); Suzuki, Minoru; Sakurai, Yoshinori [Research Reactor Institute, Kyoto University, Osaka (Japan); Sugiyama, Hirotaka [Cooperative Unit of Medicine and Engineering, University of Tokyo Hospital, Tokyo (Japan); Kajiyama, Tetsuya [Kyushu Industrial Sources Foundation, Miyazaki (Japan); Nishimura, Ryohei [Dept of Veternary Surgery, University of Tokyo Veternary Hospital, Tokyo (Japan); Ono, Koji [Research Reactor Institute, Kyoto University, Osaka (Japan); Nakajima, Jun; Ono, Minoru [Dept of Cardiothracic Surgery, University of Tokyo Hospital, Tokyo (Japan); Eriguchi, Masazumi [Cooperative Unit of Medicine and Engineering, University of Tokyo Hospital, Tokyo (Japan)] [Department of Surgery, Shin-Yamanote Hospital, Saitama (Japan); Takahashi, Hiroyuki [Dept of Nuclear Engineering and Management, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)] [Cooperative Unit of Medicine and Engineering, University of Tokyo Hospital, Tokyo (Japan)

    2011-12-15

    Introduction: Hepatocellular carcinoma (HCC) is one of the most difficult to cure with surgery, chemotherapy, or other combinational therapies. In the treatment of HCC, only 30% patients can be operated due to complication of liver cirrhosis or multiple intrahepatic tumours. Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between {sup 10}B atoms and thermal neutrons, so it is necessary to accumulate a sufficient quantity of {sup 10}B atoms in tumour cells for effective tumour cell destruction by BNCT. Water-in-oil-in-water (WOW) emulsion has been used as the carrier of anti-cancer agents on intra-arterial injections in clinical. In this study, we prepared {sup 10}BSH entrapped WOW emulsion by double emulsifying technique using iodized poppy-seed oil (IPSO), {sup 10}BSH and surfactant, for selective intra-arterial infusion to HCC, and performed simulations of the irradiation in order to calculate the dose delivered to the patients. Materials and methods: WOW emulsion was administrated with intra-arterial injections via proper hepatic artery on VX-2 rabbit hepatic tumour models. We simulated the irradiation of epithermal neutron and calculated the dose delivered to the tissues with JAEA computational dosimetry system (JCDS) at JRR4 reactor of Japan Atomic Research Institute, using the CT scans of a HCC patient. Results and discussions: The {sup 10}B concentrations in VX-2 tumour obtained by delivery with WOW emulsion were superior to those by conventional IPSO mix emulsion. According to the rabbit model, the boron concentrations (ppm) in tumour, normal liver tissue, and blood are 61.7, 4.3, and 0.1, respectively. The results of the simulations show that normal liver biologically weighted dose is restricted to 4.9 Gy-Eq (CBE; liver tumour: 2.5, normal liver: 0.94); the maximum, minimum, and mean tumour weighted dose are 43.1, 7.3, and 21.8 Gy-Eq, respectively, in 40 min irradiation. In this study, we show that {sup 10}B

  14. Optimum design of a moderator system based on dose calculation for an accelerator driven Boron Neutron Capture Therapy.

    Science.gov (United States)

    Inoue, R; Hiraga, F; Kiyanagi, Y

    2014-06-01

    An accelerator based BNCT has been desired because of its therapeutic convenience. However, optimal design of a neutron moderator system is still one of the issues. Therefore, detailed studies on materials consisting of the moderator system are necessary to obtain the optimal condition. In this study, the epithermal neutron flux and the RBE dose have been calculated as the indicators to look for optimal materials for the filter and the moderator. As a result, it was found that a combination of MgF2 moderator with Fe filter gave best performance, and the moderator system gave a dose ratio greater than 3 and an epithermal neutron flux over 1.0×10(9)cm(-2)s(-1).

  15. Implantation damage and anomalous diffusion of implanted boron in silicon through SiO[sub 2] films

    Energy Technology Data Exchange (ETDEWEB)

    Kaabi, L. (Lab. de Physique de la Matiere, Inst. National des Sciences Appliquees de Lyon, 69 - Villeurbanne (France)); Gontrand, C. (Lab. de Physique de la Matiere, Inst. National des Sciences Appliquees de Lyon, 69 - Villeurbanne (France)); Lemiti, M. (Lab. de Physique de la Matiere, Inst. National des Sciences Appliquees de Lyon, 69 - Villeurbanne (France)); Balland, B. (Lab. de Physique de la Matiere, Inst. National des Sciences Appliquees de Lyon, 69 - Villeurbanne (France))

    1993-07-16

    Boron is implanted in crystalline silicon through oxide layers with different thicknesses. The implantation is carried out at various doses and energies of interest in ultra large scale integration (ULSI) application. Rapid thermal annealings (RTA) are used to obtain shallow junctions and electrical activation of the B atoms. However, transient enhanced diffusion induced by implantation damage can be observed. The boron concentration profiles before and after annealing are obtained with secondary ion mass spectrometry (SIMS). It is found that the diffusion transient in the tail region of the boron profile increases with decreasing oxide thickness. Even more, if the implantation damage concerns mostly the oxide, i.e. when the concentration peak is located in this oxide, the oxygen knocked into the silicon substrate could play this way an important role in restricting the boron diffusion, which is good to obtain very shallow junctions. On the other hand, for thinner oxide, boron enhanced diffusion is attributed to the implantation induced damage into silicon at high doses. The diffusion process of boron in oxide and moncrystalline silicon during rapid thermal annealing is investigated. The boron diffusion profiles obtained by computer simulation are compared with the measured results. It is shown by this comparison that the intrinsic coefficient cannot be considered as constant along all the silicon depth. (orig.)

  16. Effects of boron addition on a-Si90Ge10:H films obtained by low frequency plasma enhanced chemical vapour deposition

    Science.gov (United States)

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

    2005-06-01

    Optical, structural and electric properties of (a-(Si90Ge10)1-yBy:H) thin film alloys, deposited by low frequency plasma enhanced chemical vapour deposition, are presented. The chemical bonding structure has been studied by IR spectroscopy, while the composition was investigated by Raman spectroscopy. A discussion about boron doping effects, in the composition and bonding of samples, is presented. Transport of carriers has been studied by measurement of the conductivity dependence on temperature, which increases from 10-3 to 101 Ω-1 cm-1 when the boron content varies from 0 to 50%. Similarly, the activation energy is between 0.62 and 0.19 eV when the doping increases from 0 to 83%. The optical properties have been determined from the film's optical transmission, using Swanepoel's method. It is shown that the optical gap varies from 1.3 to 0.99 eV.

  17. Dose Determination using alanine detectors in a Mixed Neutron and Gamma Field for Boron Neutron Capture Therapy of Liver Malignancies

    DEFF Research Database (Denmark)

    Schmitz, T.; Blaickner, M.; Ziegner, M.

    2011-01-01

    be suitable for measurements in mixed neutron and gamma fields. Materials and Methods Two experiments have been carried out in the thermal column of the TRIGA Mark II reactor at the University of Mainz. Alanine dosimeters have been irradiated in a phantom and in liver tissue. Results For the interpretation......, in combination with flux measurements and Monte Carlo calculations with FLUKA, suggest that it is possible to establish a system for monitoring the dose in a mixed neutron and gamma field for BNCT and other applications in radiotherapy....

  18. Nanoparticle location and material dependent dose enhancement in X-ray radiation therapy.

    Science.gov (United States)

    Hossain, Mainul; Su, Ming

    2012-11-01

    Nanoparticles of high atomic number (Z) materials can act as radiosensitizers to enhance radiation dose delivered to tumors. An analytical approach is used to calculate dose enhancements to tumor endothelial cells and their nuclei for a series of nanoparticles (bismuth, gold and platinum) located at different locations relative to nuclei by considering contributions from both photoelectrons and Auger electrons. The ratio of the dose delivered to cells with and without the nanoparticles is known as the dose enhancement factor (DEF). DEFs depend on material composition, size and location of nanoparticles with respect to the cell and the nucleus. Energy of irradiating X-ray beam affects X-ray absorption by nanoparticles and plays an important role in dose enhancements. For diagnostic X-ray sources, bismuth nanoparticles provide higher dose enhancements than gold and platinum nanoparticles for a given nanoparticle size, concentration and location. The highest DEFs are achieved for nanoparticles located closest to the nucleus where energy depositions from short range Auger electrons are maximum. With nanoparticles ranging in diameter between 2-400 nm, the dose enhancement increases with decrease in particle size. The results are useful in finding optimized conditions for nanoparticle enhanced X-ray radiation therapy of cancer.

  19. Experimental study on x-rays dose enhancement effects for floating gate ROMs

    CERN Document Server

    Guo Hong Xia; Chen Yu Sheng; Han Fu Bin; He Chao Hui; Zhao Hui

    2002-01-01

    Experimental results of x-ray dose enhancement effects are given for floating gate read-only memory (ROMs) irradiated in the Beijing Synchrotron Radiation Facility. The wrong byte numbers vs. total irradiation dose have been tested and the equivalent relation of total dose damage is provided compared the response of devices irradiated with sup 6 sup 0 Co gamma-ray source. The x-ray dose enhancement factors for floating gate ROMs are obtained firstly in China. These results can be an effective evaluation data for x-rays radiation hardening technology

  20. Study of hard X-ray dose enhancement effects for some kinds of semiconductor devices

    CERN Document Server

    Guo Hong Xia; Chen Yu Sheng; Zhou Hui; He Chao Hui; Xie Ya Ning; Huang Yu Ying; He Wei; Hu Tian Dou

    2002-01-01

    Experimental results of X-ray dose enhancement effects are given for CMOS4069 and floating gate ROMs irradiated in Beijing Synchrotron Radiation Facility and in cobalt source. Shift of threshold voltage vs. total dose for CMOS4069 and the errors vs. total dose for 28f256 and 29c256 have been tested on line and the equivalent relation of total dose damage under the same accumulated dose is provided comparing the response of devices irradiated by X-ray and gamma-ray source. These results can be provided for X-ray radiation hardening technology as an effective evaluation data

  1. Tetraploidy Enhances Boron-Excess Tolerance in Carrizo Citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.)

    Science.gov (United States)

    Ruiz, Marta; Quiñones, Ana; Martínez-Alcántara, Belén; Aleza, Pablo; Morillon, Raphaël; Navarro, Luis; Primo-Millo, Eduardo; Martínez-Cuenca, Mary-Rus

    2016-01-01

    Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport. Highlights Tetraploidy enhances B excess tolerance in citrange Carrizo Expression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidies B tolerance is attributed to root anatomical modifications induced by genome duplication The rootstock 4x citrange carrizo may prevent citrus trees from B excess. PMID:27252717

  2. Enhanced charge trapping in bipolar spacer oxides during low-dose-rate irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fleetwood, D.M.; Reber, R.A. Jr.; Winokur, P.S. [Sandia National Labs., Albuquerque, NM (United States); Kosier, S.L.; Schrimpf, R.D. [Arizona Univ., Tucson, AZ (United States). Dept. of Electrical and Computer Engineering; Nowlin, R.N. [Air Force Phillips Laboratory, Albuquerque, NM (United States); Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States); DeLaus, M. [Analog Devices, Wilmington, MA (United States)

    1994-03-01

    Thermally-stimulated-current and capacitance-voltage measurements reveal enhanced hole trapping in bipolar spacer-oxide capacitors irradiated at 0 V at low dose rates. Possible mechanisms and implications for bipolar low-rate response are discussed.

  3. Thermal-stress effects on enhanced low-dose-rate sensitivity of linear bipolar circuits

    Energy Technology Data Exchange (ETDEWEB)

    SHANEYFELT,MARTY R.; SCHWANK,JAMES R.; WITCZAK,STEVEN C.; RIEWE,LEONARD CHARLES; WINOKUR,PETER S.; HASH,GERALD L.; PEASE,R.L.; FLEETWOOD,D.M.

    2000-02-17

    Thermal-stress effects are shown to have a significant impact on the enhanced low-dose-rate sensitivity of linear bipolar circuits. Implications of these results on hardness assurance testing and mechanisms are discussed.

  4. Low dose radiation enhances the Locomotor activity of D. melanogaster

    Energy Technology Data Exchange (ETDEWEB)

    Seong, Ki Moon; Lee, Buyng Sub; Nam Seon Young; Kim, Ji Young; Yang, Kwang Hee; Choi, Tae In; Kim, Cha Soon [Radiation Effect Research Team, Radiation Health Research Institute, Korea Hydro and Nuclear Power Co., Ltd., Gyeongju (Korea, Republic of)

    2013-04-15

    Mild stresses at low level including radiation can induce the beneficial effects in many vertebrate and invertebrate species. However, a large amount of studies in radiation biology have focused on the detrimental effects of high dose radiation (HDR) such as the increased incidence of cancers and developmental diseases. Low dose radiation (LDR) induces biologically favorable effects in diverse fields, for example, cancer development, genomic instability, immune response, and longevity. Our previous data indicated that LDR promotes cells proliferation of which degree is not much but significant, and microarray data explained that LDR irradiated fruit flies showing the augmented immunity significantly changed the program for gene expression of many genes in Gene Ontology (GO) categories related to metabolic process. Metabolic process in development one of major contributors in organism growth, interbreeding, motility, and aging. Therefore, it is valuable to examine whether LDR change the physiological parameters related to metabolism, and how LDR regulates the metabolism in D. melanogaster. In this study, to investigate that LDR influences change of the metabolism, a representative parameter, locomotor activity. In addition, the activation of several cellular signal molecules was determined to investigate the specific molecular mechanism of LDR effects on the metabolism. We explored whether ionizing radiation affects the motility activity. We performed the RING assays to evaluate the locomotor activity, a representative parameter presenting motility of fruit flies. HDR dramatically decreased the motor activity of irradiated flies. Surprisingly, the irradiated flies at low dose radiation in both acute and chronic showed the significantly increased locomotor activity, compared to non-irradiated flies. Irradiation would induce change of the several signal pathways for flies to respond to it. The activation of some proteins involved in the cells proliferation and stress

  5. Chitosan-coated boron nitride nanospheres enhance delivery of CpG oligodeoxynucleotides and induction of cytokines

    Directory of Open Access Journals (Sweden)

    Zhang H

    2013-05-01

    G oligodeoxynucleotides. The loading capacity of the CpG oligodeoxynucleotides depended on the molecular weight of chitosan, which affected the positive charge density on the surface of the BNNS. CpG oligodeoxynucleotides loaded onto BNNS-CS complexes significantly enhanced production of interleukin-6 and tumor necrosis factor-a by peripheral blood mononuclear cells compared with CpG oligodeoxynucleotides directly loaded onto BNNS, or when Lipofectamine™ 2000 was used as the carrier. The molecular weight of the chitosan used to coat the BNNS affected the magnitude of cytokine induction by varying the strength of condensation of the CpG oligodeoxynucleotides. Conclusion: Although the loading capacity of BNNS coated with low molecular weight chitosan preparations was the lowest of all the preparations, they induced the highest levels of cytokines. Keywords: chitosan, boron nitride nanospheres, CpG oligodeoxynucleotides, drug delivery, cytokines

  6. Enhancement in creep resistance of Ti–6Al–4V alloy due to boron addition

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Gaurav [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Satyanarayana, D.V.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Pederson, Robert [Research and Technology Centre, GKN Aerospace Engine Systems, S-46181 Trollhättan (Sweden); Division of Materials Science, Luleä University of Technology, S-97187 Luleä (Sweden); Datta, Ranjan [International Centre for Materials Science, JNCASR, Jakkur PO, Bangalore 560064 (India); Ramamurty, Upadrasta, E-mail: ramu@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Centre of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-03-01

    The addition of B, up to about 0.1 wt%, to Ti–6Al–4V (Ti64) reduces its as-cast grain and colony sizes by an order of magnitude. In this paper, the creep resistance of this alloy modified with 0.06 and 0.11 wt% B additions was investigated in the temperature range of 475–550 °C and compared with that of the base alloy. Conventional dead-weight creep tests as well as stress relaxation tests were employed for this purpose. Experimental results show that the B addition enhances both elevated temperature strength and creep properties of Ti64, especially at the lower end of the temperatures investigated. The steady state creep rate in the alloy with 0.11 wt% B was found to be an order of magnitude lower than that in the base alloy, and both the strain at failure as well as the time for rupture increases with the B content. These marked improvements in the creep resistance due to B addition to Ti64 were attributed primarily to the increased number of inter-phase interfaces – a direct consequence of the microstructural refinement that occurs with the B addition – that provide resistance to dislocation motion.

  7. Enhanced growth and osteogenic differentiation of human osteoblast-like cells on boron-doped nanocrystalline diamond thin films.

    Directory of Open Access Journals (Sweden)

    Lubica Grausova

    Full Text Available Intrinsic nanocrystalline diamond (NCD films have been proven to be promising substrates for the adhesion, growth and osteogenic differentiation of bone-derived cells. To understand the role of various degrees of doping (semiconducting to metallic-like, the NCD films were deposited on silicon substrates by a microwave plasma-enhanced CVD process and their boron doping was achieved by adding trimethylboron to the CH(4:H(2 gas mixture, the B∶C ratio was 133, 1000 and 6700 ppm. The room temperature electrical resistivity of the films decreased from >10 MΩ (undoped films to 55 kΩ, 0.6 kΩ, and 0.3 kΩ (doped films with 133, 1000 and 6700 ppm of B, respectively. The increase in the number of human osteoblast-like MG 63 cells in 7-day-old cultures on NCD films was most apparent on the NCD films doped with 133 and 1000 ppm of B (153,000 ± 14,000 and 152,000 ± 10,000 cells/cm(2, respectively, compared to 113,000 ± 10,000 cells/cm(2 on undoped NCD films. As measured by ELISA per mg of total protein, the cells on NCD with 133 and 1000 ppm of B also contained the highest concentrations of collagen I and alkaline phosphatase, respectively. On the NCD films with 6700 ppm of B, the cells contained the highest concentration of focal adhesion protein vinculin, and the highest amount of collagen I was adsorbed. The concentration of osteocalcin also increased with increasing level of B doping. The cell viability on all tested NCD films was almost 100%. Measurements of the concentration of ICAM-1, i.e. an immunoglobuline adhesion molecule binding inflammatory cells, suggested that the cells on the NCD films did not undergo significant immune activation. Thus, the potential of NCD films for bone tissue regeneration can be further enhanced and tailored by B doping and that B doping up to metallic-like levels is not detrimental for cells.

  8. Energy Optimization And Calculation Of Dose Absorption Enhancement Factor In Photon Activation Therapy

    Directory of Open Access Journals (Sweden)

    Hassan Ranjbar

    2010-06-01

    Full Text Available Introduction: Secondary radiation such as photoelectrons, Auger electrons and characteristic radiations cause a local boost in dose for a tumor when irradiated with an external X-ray beam after being loaded with elements capable of activating the tumor, e.g.; I and Gd. Materials and Methods:  In this investigation, the MCNPX code was used for simulation and calculation of dose enhancement factor for a tumor loaded with activating elements. The designed model comprised the X-ray source, phantom (target tissue and loaded tumor with activating agent, detector, interactions modeling and results. The source was defined as monochromatic and plane surface situated at 50 cm (z = 50. Phantom geometry was a 10 × 10 × 10 cm3 cube centered at (0, 0, 0 with a 2.2 × 2.2 × 2.2 cm3 cubic tumor with a center located at 3 cm depth inside the phantom Results: Dose enhancement factor and optimum energy in radiotherapy are evaluated using the photon activation therapy method. Result show that the dose enhancement factor increases with activating concentration in the tumor. The maximum dose enhancement factor for iodine in the tumor occurs for photons in the energy range of 50-60 keV. Dose uniformity is less for lower energy photons within the activated region inside the tumor. Results indicate that the dose enhancement factor varies linearly with the activating concentration agent. Discussion and Conclusion: In this study, the obtained results point out a considerable enhancement in dose in the presence of activating agents in the tumor regions.

  9. Evaluation of the local dose enhancement in the combination of proton therapy and nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Rovira, I., E-mail: immamartinez@gmail.com; Prezado, Y. [Laboratoire d’Imagerie et Modélisation en Neurobiologie et Cancérologie (IMNC), Centre National de la Recherche Scientifique (CNRS), Université Paris 7 and 11, Campus Universitaire, Bât. 440, 1er étage, 15 rue Georges Clemenceau, Orsay Cedex 91406 (France)

    2015-11-15

    Purpose: The outcome of radiotherapy can be further improved by combining irradiation with dose enhancers such as high-Z nanoparticles. Since 2004, spectacular results have been obtained when low-energy x-ray irradiations have been combined with nanoparticles. Recently, the same combination has been explored in hadron therapy. In vitro studies have shown a significant amplification of the biological damage in tumor cells charged with nanoparticles and irradiated with fast ions. This has been attributed to the increase in the ionizations and electron emissions induced by the incident ions or the electrons in the secondary tracks on the high-Z atoms, resulting in a local energy deposition enhancement. However, this subject is still a matter of controversy. Within this context, the main goal of the authors’ work was to provide new insights into the dose enhancement effects of nanoparticles in proton therapy. Methods: For this purpose, Monte Carlo calculations (GATE/GEANT4 code) were performed. In particular, the GEANT4-DNA toolkit, which allows the modeling of early biological damages induced by ionizing radiation at the DNA scale, was used. The nanometric radial energy distributions around the nanoparticle were studied, and the processes (such as Auger deexcitation or dissociative electron attachment) participating in the dose deposition of proton therapy treatments in the presence of nanoparticles were evaluated. It has been reported that the architecture of Monte Carlo calculations plays a crucial role in the assessment of nanoparticle dose enhancement and that it may introduce a bias in the results or amplify the possible final dose enhancement. Thus, a dosimetric study of different cases was performed, considering Au and Gd nanoparticles, several nanoparticle sizes (from 4 to 50 nm), and several beam configurations (source-nanoparticle distances and source sizes). Results: This Monte Carlo study shows the influence of the simulations’ parameters on the local

  10. Optimal moderator materials at various proton energies considering photon dose rate after irradiation for an accelerator-driven ⁹Be(p, n) boron neutron capture therapy neutron source.

    Science.gov (United States)

    Hashimoto, Y; Hiraga, F; Kiyanagi, Y

    2015-12-01

    We evaluated the accelerator beam power and the neutron-induced radioactivity of (9)Be(p, n) boron neutron capture therapy (BNCT) neutron sources having a MgF2, CaF2, or AlF3 moderator and driven by protons with energy from 8 MeV to 30 MeV. The optimal moderator materials were found to be MgF2 for proton energies less than 10 MeV because of lower required accelerator beam power and CaF2 for higher proton energies because of lower photon dose rate at the treatment position after neutron irradiation.

  11. Quantitative investigation of physical factors contributing to gold nanoparticle-mediated proton dose enhancement

    Science.gov (United States)

    Cho, Jongmin; Gonzalez-Lepera, Carlos; Manohar, Nivedh; Kerr, Matthew; Krishnan, Sunil; Cho, Sang Hyun

    2016-03-01

    Some investigators have shown tumor cell killing enhancement in vitro and tumor regression in mice associated with the loading of gold nanoparticles (GNPs) before proton treatments. Several Monte Carlo (MC) investigations have also demonstrated GNP-mediated proton dose enhancement. However, further studies need to be done to quantify the individual physical factors that contribute to the dose enhancement or cell-kill enhancement (or radiosensitization). Thus, the current study investigated the contributions of particle-induced x-ray emission (PIXE), particle-induced gamma-ray emission (PIGE), Auger and secondary electrons, and activation products towards the total dose enhancement. Specifically, GNP-mediated dose enhancement was measured using strips of radiochromic film that were inserted into vials of cylindrical GNPs, i.e. gold nanorods (GNRs), dispersed in a saline solution (0.3 mg of GNRs/g or 0.03% of GNRs by weight), as well as vials containing water only, before proton irradiation. MC simulations were also performed with the tool for particle simulation code using the film measurement setup. Additionally, a high-purity germanium detector system was used to measure the photon spectrum originating from activation products created from the interaction of protons and spherical GNPs present in a saline solution (20 mg of GNPs/g or 2% of GNPs by weight). The dose enhancement due to PIXE/PIGE recorded on the films in the GNR-loaded saline solution was less than the experimental uncertainty of the film dosimetry (PIGE, and activation products contribute minimally to GNP/GNR-mediated proton dose enhancement, whereas Auger/secondary electrons contribute significantly but only at short distances (<100 nm) from GNPs/GNRs.

  12. Enhancing the removal of arsenic, boron and heavy metals in subsurface flow constructed wetlands using different supporting media.

    Science.gov (United States)

    Allende, K Lizama; Fletcher, T D; Sun, G

    2011-01-01

    The presence of arsenic and heavy metals in drinking water sources poses a serious health risk due to chronic toxicological effects. Constructed wetlands have the potential to remove arsenic and heavy metals, but little is known about pollutant removal efficiency and reliability of wetlands for this task. This lab-scale study investigated the use of vertical subsurface flow constructed wetlands for removing arsenic, boron, copper, zinc, iron and manganese from synthetic wastewater. Gravel, limestone, zeolite and cocopeat were employed as wetland media. Conventional gravel media only showed limited capability in removing arsenic, iron, copper and zinc; and it showed virtually no capability in removing manganese and boron. In contrast, alternative wetland media: cocopeat, zeolite and limestone, demonstrated significant efficiencies--in terms of percentage removal and mass rate per m3 of wetland volume--for removing arsenic, iron, manganese, copper and zinc; their ability to remove boron, in terms of mass removal rate, was also higher than that of the gravel media. The overall results demonstrated the potential of using vertical flow wetlands to remove arsenic and metals from contaminated water, having cocopeat, zeolite or limestone as supporting media.

  13. Gadodiamide injection for enhancement of MRI in the CNS. Applications, dose, field and time dependence

    Energy Technology Data Exchange (ETDEWEB)

    Aakeson, P.

    1996-10-01

    Gadodiamide injection was comparable to Gd-DTPA with regard to both safety and diagnostic efficiency in the central nervous system. The contrast effect of Gd contrast agents is higher at 1.5 T than at 0.3 T both in phantoms and patients with a maximum ratio (signal lesion/signal grey matter) more than 50% higher at 1.5 T. To achieve high contrast effect, heavily T1-weighted images are important. Prolonging the TR from 400 ms to 600 ms reduced the ratio by 15-45% depending on concentration. The effective time window for imaging of BBB (Blood-Brain Barrier) damage is between 2-5 and 25-30 minutes after injection and several scans can be performed without loss of enhancement. To provide maximum detectability of BBB damage in patients, higher doses of Gd contrast media should be useful, especially at low field strengths, as the doses used clinically today do not utilize the maximum contrast effect. High-dose (0.3 mmol/kg b.w.) contrast enhanced MRI (0.3 T) with Gadodiamide injection allowed detection of significantly more and smaller metastases (i.e. BBB damage) than standard dose (0.1 mmol/kg b.w.) High dose contrast-enhanced MRI (0.3 T) did not increase the diagnostic information for the evaluation of patients with failed back surgery syndrome compared to standard dose MRI. 55 refs, 9 figs, 10 tabs.

  14. Crescimento e teores de boro em plantas de eucalipto (Eucalyptus citriodora cultivadas em dois latossolos sob influência de doses de boro e disponibilidade de água Growth and boron contents in eucalyptus (Eucalyptus citriodora growing in two latosols under the influence of boron rates and water availability

    Directory of Open Access Journals (Sweden)

    Sílvio Júnio Ramos

    2009-02-01

    Full Text Available Este trabalho objetivou avaliar o efeito da aplicação de doses de boro no crescimento de Eucalyptus citriodora em um Latossolo V ermelho-Escuro e um Latossolo Vermelho-Amarelo, submetidos a diferentes tensões hídricas. O experimento foi conduzido em casa de vegetação, no Departamento de Ciência do Solo da Universidade Federal de Lavras, em Lavras, MG, usando-se vasos com três dm³ de solo. Utilizou-se o delineamento experimental inteiramente casualizado, em esquema fatorial 5 x 2 x 2, sendo cinco doses de B (0,00; 0,25; 0,75; 2,25; e 6,25 mg kg-1; e dois tipos de Latossolo: Latossolo Vermelho-Escuro (LE e Latossolo Vermelho-Amarelo (LV e duas tensões hídricas (-0,033 e -0,010 MPa, com quatro repetições. Os resultados indicaram que tanto o LV quanto o LE, nas suas condições naturais, não supriram as exigências de B em Eucalyptus citriodora. Contudo, os maiores incrementos na produção de matéria seca das plantas foram observados em baixas doses de B aplicadas. A umidade do solo é um fator importante no aproveitamento de B do solo pelo Eucalyptus citriodora.The present work was carried out to evaluate the effect of Boron rates on the growth of Eucalyptus citriodora in two Latosols, submitted to different water tensions. The experiment was carried out in a greenhouse at the Soil Science Department of the Federal University of Lavras-MG and it was arranged in a completely randomized design in a 5 x 2 x 2 factorial scheme with four replications, five B rates (0.0; 0.25; 0.75; 2.25; and 6.25 mg kg-1 and two soils, Dark Red Latosol (LEr and Red Yellow Latosol (LVm with two moisture levels (-0.033 and -0.010 MPa. The results obtained showed that under natural conditions, neither LEr nor LVm was able to supply Eucalyptus citriodora the requirements for Boron. However, the highest increase in dry matter yield was obtained at low rates of Boron supplied. Soil moisture was an important factor in Boron uptake for eucalyptus plants.

  15. Effects of boron addition on a-Si{sub 90}Ge{sub 10}:H films obtained by low frequency plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Arllene M [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis E Erro no. 1, Santa Maria Tonantzintla, CP 72840, Puebla, Puebla (Mexico); Universidad Popular Autonoma del Estado de Puebla (UPAEP), 21 Sur 1103 Colonia Santiago, CP 72160, Puebla, Puebla (Mexico); Renero, Francisco J [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis E Erro no. 1, Santa Maria Tonantzintla, CP 72840, Puebla, Puebla (Mexico); Zuniga, Carlos [Instituto Nacional de AstrofIsica, Optica y Electronica (INAOE), Luis E Erro no. 1, Santa MarIa Tonantzintla, CP 72840, Puebla, Puebla (Mexico); Torres, Alfonso [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Luis E Erro no. 1, Santa MarIa Tonantzintla, CP 72840, Puebla, Puebla (Mexico); Santiago, Cesar [Universidad Politecnica de Tulancingo, Prolongacion Guerrero 808 Colonia Caltengo, CP 43626, Tulancingo, Hidalgo (Mexico)

    2005-06-29

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

  16. Boron neutron capture therapy (BNCT) for liver metastasis in an experimental model: dose–response at five-week follow-up based on retrospective dose assessment in individual rats

    Energy Technology Data Exchange (ETDEWEB)

    Emiliano C. C. Pozzi; Veronica A. Trivilin; Lucas L. Colombo; Andrea Monti Hughes; Silvia I. Thorp; Jorge E. Cardoso; Marcel A. Garabalino; Ana J. Molinari; Elisa M. Heber; Paula Curotto; Marcelo Miller; Maria E. Itoiz; Romina F. Aromando; David W. Nigg; Amanda E. Schwint

    2013-11-01

    Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. Employing an experimental model of liver metastases in rats, we recently demonstrated that BNCT mediated by boronophenylalanine (BPA-BNCT) at 13 Gy prescribed to tumor is therapeutically useful at 3-week follow-up. The aim of the present study was to evaluate dose–response at 5-week follow-up, based on retrospective dose assessment in individual rats. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA-BNCT (n = 19), Beam only (n = 8) and Sham (n = 7) (matched manipulation, no treatment). For each rat, neutron flux was measured in situ and boron content was measured in a pre-irradiation blood sample for retrospective individual dose assessment. For statistical analysis (ANOVA), individual data for the BPA-BNCT group were pooled according to absorbed tumor dose, BPA-BNCT I: 4.5–8.9 Gy and BPA-BNCT II: 9.2–16 Gy. At 5 weeks post-irradiation, the tumor surface area post-treatment/pre-treatment ratio was 12.2 +/- 6.6 for Sham, 7.8 +/- 4.1 for Beam only, 4.4 +/- 5.6 for BPA-BNCT I and 0.45 +/- 0.20 for BPA-BNCT II; tumor nodule weight was 750 +/- 480 mg for Sham, 960 +/- 620 mg for Beam only, 380 +/- 720 mg for BPA-BNCT I and 7.3 +/- 5.9 mg for BPA-BNCT II. The BPA-BNCT II group exhibited statistically significant tumor control with no contributory liver toxicity. Potential threshold doses for tumor response and significant tumor control were established at 6.1 and 9.2 Gy, respectively.

  17. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy.

    Science.gov (United States)

    Siuzdak, K; Bogdanowicz, R; Sawczak, M; Sobaszek, M

    2015-01-14

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (∼200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm(-2) at a scan rate of 10 mV s(-1) for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  18. Enhanced molecular order in polythiophene films electropolymerized in a mixed electrolyte of anionic surfactants and boron trifluoride diethyl etherate.

    Science.gov (United States)

    Santoso, Handoko T; Singh, Virendra; Kalaitzidou, Kyriaki; Cola, Baratunde A

    2012-03-01

    We synthesized polythiophene (PTh) films on stainless steel electrodes using chronoamperometry in boron trifluoride diethyl etherate (BFEE) electrolyte with anionic surfactants. The presence of the anionic surfactants in BFEE reduced the oxidation potential of thiophene and increased the oxidation current during electropolymerization. The measured in-plane electrical conductivity of PTh films synthesized in the presence of anionic surfactants was up to 300% higher than that of films synthesized under similar conditions without surfactants. The observed increase in conductivity reflects the improved order and packing of polymer chains revealed by X-ray diffraction.

  19. Sharpening peripheral dose gradient via beam number enhancement from patient head tilt for stereotactic brain radiosurgery

    Science.gov (United States)

    Chiu, Joshua; Pierce, Marlon; Braunstein, Steve E.; Theodosopoulos, Philip V.; McDermott, Michael W.; Sneed, Penny K.; Ma, Lijun

    2016-10-01

    Sharp dose fall-off is the hallmark of brain radiosurgery for the purpose of delivering high dose radiation to the target while minimizing peripheral dose to regional normal brain tissue. In this study, a technique was developed to enhance the peripheral dose gradient by magnifying the total number of beams focused toward each isocenter through pre-programmed patient head tilting. This technique was tested in clinical settings on a dedicated brain radiosurgical system (GKPFX, Gamma Knife Perfexion, Elekta Oncology) by comparing dosimetry as well as delivery efficiency for 20 radiosurgical cases previously treated with the system. The 3-fold beam number enhancement (BNE) treatment plans were found to produce nearly identical target volume coverage (absolute value    0.2) and dose conformity (BNE CI  =  1.41  ±  0.22 versus 1.41  ±  0.11, P  >  0.99) as the original treatment plans. The total beam-on time for the 3-fold BNE treatment plans were also found to be comparable (peripheral dose gradient for brain radiosurgery. This work was presented in part at the 2015 ISRS Congress in Yokohama Japan.

  20. Mechanisms of Enhanced Cell Killing at Low Doses: Implications for Radiation Risk

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Peter J. Johnston; Dr. George D. Wilson

    2003-10-15

    We have shown that cell lethality actually measured after exposure to low-doses of low-LET radiation, is markedly enhanced relative to the cell lethality previously expected by extrapolation of the high-dose cell-killing response. Net cancer risk is a balance between cell transformation and cell kill and such enhanced lethality may more than compensate for transformation at low radiation doses over a least the first 10 cGy of low-LET exposure. This would lead to a non-linear, threshold, dose-risk relationship. Therefore our data imply the possibility that the adverse effects of small radiation doses (<10 cGy) could be overestimated in specific cases. It is now important to research the mechanisms underlying the phenomenon of low-dose hypersensitivity to cell killing, in order to determine whether this can be generalized to safely allow an increase in radiation exposure limits. This would have major cost-reduction implications for the whole EM program.

  1. The enhanced low dose rate sensitivity of a linear voltage regulator with different biases

    Institute of Scientific and Technical Information of China (English)

    Wang Yiyuan; Lu Wu; Ren Diyuan; Guo Qi; Yu Xuefeng; Gao Bo

    2011-01-01

    A linear voltage regulator was irradiated by 60Co γ at high and low dose rates with two bias conditions to investigate the dose rate effect.The devices exhibit enhanced low dose rate sensitivity (ELDRS) under both biases.Comparing the enhancement factors between zero and working biases,it was found that the ELDRS is more severe under zero bias conditions.This confirms that the ELDRS is related to the low electric field in a bipolar structure.The reasons for the change in the line regulation and the maximum drive current were analyzed by combining the principle of linear voltage regulator with irradiation response of the transistors and error amplifier in the regulator.This may be helpful for designing radiation hardened devices.

  2. Measurement bias dependence of enhanced bipolar gain degradation at low dose rates

    Energy Technology Data Exchange (ETDEWEB)

    Witczak, S.C.; Lacoe, R.C.; Mayer, D.C. [Aerospace Corp., Los Angeles, CA (United States). Electronics Technology Center; Schrimpf, R.D.; Barnaby, H.J.; Galloway, K.F. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Electrical and Computer Engineering; Pease, R.L. [RLP Research, Inc., Albuquerque, NM (United States); Fleetwood, D.M. [Sandia National Labs., Albuquerque, NM (United States)

    1998-03-01

    Oxide trapped charge, field effects from emitter metallization, and high level injection phenomena moderate enhanced gain degradation of lateral pnp transistors at low dose rates. Hardness assurance tests at elevated irradiation temperatures require larger design margins for low power measurement biases.

  3. Half-dose gadoxetic acid-enhanced liver magnetic resonance imaging in patients at risk for nephrogenic systemic fibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kyoung Doo [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul 135-710 (Korea, Republic of); Kim, Seong Hyun, E-mail: kshyun@skku.edu [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul 135-710 (Korea, Republic of); Lee, Jisun; Kang, Kyung A. [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul 135-710 (Korea, Republic of); Kim, Joungyoun; Yoo, Heejin [Biostatistics and Clinical Epidemiology Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul 135-710 (Korea, Republic of)

    2015-03-15

    Highlights: •Half dose of gadoxetic acid achieved more than 75% enhancement degree of a standard dose. •No significant difference was observed in enhancement quality between half-dose and standard-dose MRIs for all upper abdominal organs. •Liver MRI using half-dose gadoxetic acid at 3-T can be a feasible alternative for standard-dose MRI in patients at risk for NSF. -- Abstract: Purpose: To evaluate the feasibility of half-dose gadoxetic acid (0.0125 mmol/kg) for liver MRI at 3-T compared to standard-dose (0.025 mmol/kg) in patients at risk for nephrogenic systemic fibrosis (NSF). Materials and methods: Forty patients who underwent both half-dose and standard-dose gadoxetic acid-enhanced MRIs were included. Contrast enhancement index (CEI) was calculated for liver, aorta, pancreas and kidney. Two observers independently rated and performed a one-to-one direct comparison of enhancement quality for both groups. Results: Liver CEIs were not significantly different on arterial phase between the two groups but CEIs of standard-dose MRIs were greater than half-dose MRIs on other phases (P < 0.001). CEIs were not significantly different on arterial phase for the aorta or on any phases for the pancreas. Kidney CEIs of standard-dose MRIs were greater than half-dose MRIs on all phases (P < 0.05). Enhancement quality of both groups was diagnostic and did not significantly differ for any organs. In one-to-one direct comparisons of enhancement quality, equal ratings were given in 87.5% (35/40) of cases by observer 1 and 85.0% (34/40) by observer 2. Conclusion: Liver MRI using half-dose gadoxetic acid at 3-T can be a feasible alternative for standard-dose MRI in patients at risk for NSF.

  4. A method for converting dose-to-medium to dose-to-tissue in Monte Carlo studies of gold nanoparticle-enhanced radiotherapy.

    Science.gov (United States)

    Koger, B; Kirkby, C

    2016-03-07

    Gold nanoparticles (GNPs) have shown potential in recent years as a means of therapeutic dose enhancement in radiation therapy. However, a major challenge in moving towards clinical implementation is the exact characterisation of the dose enhancement they provide. Monte Carlo studies attempt to explore this property, but they often face computational limitations when examining macroscopic scenarios. In this study, a method of converting dose from macroscopic simulations, where the medium is defined as a mixture containing both gold and tissue components, to a mean dose-to-tissue on a microscopic scale was established. Monte Carlo simulations were run for both explicitly-modeled GNPs in tissue and a homogeneous mixture of tissue and gold. A dose ratio was obtained for the conversion of dose scored in a mixture medium to dose-to-tissue in each case. Dose ratios varied from 0.69 to 1.04 for photon sources and 0.97 to 1.03 for electron sources. The dose ratio is highly dependent on the source energy as well as GNP diameter and concentration, though this effect is less pronounced for electron sources. By appropriately weighting the monoenergetic dose ratios obtained, the dose ratio for any arbitrary spectrum can be determined. This allows complex scenarios to be modeled accurately without explicitly simulating each individual GNP.

  5. Enhancement of Transistor-to-Transistor Variability Due to Total Dose Effects in 65-nm MOSFETs

    CERN Document Server

    Gerardin, S; Cornale, D; Ding, L; Mattiazzo, S; Paccagnella, A; Faccio, F; Michelis, S

    2015-01-01

    We studied device-to-device variations as a function of total dose in MOSFETs, using specially designed test structures and procedures aimed at maximizing matching between transistors. Degradation in nMOSFETs is less severe than in pMOSFETs and does not show any clear increase in sample-to-sample variability due to the exposure. At doses smaller than 1 Mrad( SiO2) variability in pMOSFETs is also practically unaffected, whereas at very high doses-in excess of tens of Mrad( SiO2)-variability in the on-current is enhanced in a way not correlated to pre-rad variability. The phenomenon is likely due to the impact of random dopant fluctuations on total ionizing dose effects.

  6. Single dose oral clonidine premedication does not enhance postoperative, single low dose epidural morphine analgesia in hysterectomy patients.

    Science.gov (United States)

    Oofuvong, Maliwan; Chanvej, Laksamee; Thongsuksai, Paramee

    2005-03-01

    In this randomized, double blind placebo controlled study, the authors evaluated the effects of oral clonidine premedication on very low dose epidural morphine analgesia in 50 hysterectomy patients. Patients were randomized to receive a single oral clonidine 300 microg (n = 25) or a placebo (n = 25) 90 minutes before insertion of the epidural catheter. 3 ml of 2% lidocaine with adrenaline (5 microg ml(-1) mixed with 2 mg morphine were injected via epidural, followed by an additional volume of 2% lidocaine with adrenaline (5 microg ml(-1)) titrated to T6 block height before commencing general anesthesia. The postoperative analgesia regimen was 2 mg of intravenous morphine every 10 minutes for the first 48 hr and 1 gm of oral acetaminophen every 4-6 hr after initiation of oral diet at 24-48 hr as required. Morphine consumption, acetaminophen, pain scores, and side effects were recorded thoughout 48 hr after surgery. The results show patients in the clonidine and placebo groups were not different in terms of local anesthetics dose (p = 0.27), total morphine and acetaminophen requirement (p = 0.34, p = 0.1) respectively. Pain scores at rest and movement were also not different in both groups (p = 0.83, p = 0.64) respectively. No serious adverse effects were noted. The authors concluded that oral clonidine approximately 6 microg kg(-1) does not enhance the analgesic effect of epidural morphine 2 mg after hysterectomy.

  7. Irradiation with low-dose gamma ray enhances tolerance to heat stress in Arabidopsis seedlings.

    Science.gov (United States)

    Zhang, Liang; Zheng, Fengxia; Qi, Wencai; Wang, Tianqi; Ma, Lingyu; Qiu, Zongbo; Li, Jingyuan

    2016-06-01

    Gamma irradiation at low doses can stimulate the tolerance to environmental stress in plants. However, the knowledge regarding the mechanisms underlying the enhanced tolerance induced by low-dose gamma irradiation is far from fully understood. In this study, to investigate the physiological and molecular mechanisms of heat stress alleviated by low-dose gamma irradiation, the Arabidopsis seeds were exposed to a range of doses before subjected to heat treatment. Our results showed that 50-Gy gamma irradiation maximally promoted seedling growth in response to heat stress. The production rate of superoxide radical and contents of hydrogen peroxide and malondialdehyde in the seedlings irradiated with 50-Gy dose under heat stress were significantly lower than those of controls. The activities of antioxidant enzymes, glutathione (GSH) content and proline level in the gamma-irradiated seedlings were significantly increased compared with the controls. Furthermore, transcriptional expression analysis of selected genes revealed that some components related to heat tolerance were stimulated by low-dose gamma irradiation under heat shock. Our results suggest that low-dose gamma irradiation can modulate the physiological responses as well as gene expression related to heat tolerance, thus alleviating the stress damage in Arabidopsis seedlings.

  8. Aqueously Dispersed Silver Nanoparticle-Decorated Boron Nitride Nanosheets for Reusable, Thermal Oxidation-Resistant Surface Enhanced Raman Spectroscopy (SERS) Devices

    Science.gov (United States)

    Lin, Yi; Bunker, Christopher E.; Fernandos, K. A. Shiral; Connell, John W.

    2012-01-01

    The impurity-free aqueous dispersions of boron nitride nanosheets (BNNS) allowed the facile preparation of silver (Ag) nanoparticle-decorated BNNS by chemical reduction of an Ag salt with hydrazine in the presence of BNNS. The resultant Ag-BNNS nanohybrids remained dispersed in water, allowing convenient subsequent solution processing. By using substrate transfer techniques, Ag-BNNS nanohybrid thin film coatings on quartz substrates were prepared and evaluated as reusable surface enhanced Raman spectroscopy (SERS) sensors that were robust against repeated solvent washing. In addition, because of the unique thermal oxidation-resistant properties of the BNNS, the sensor devices may be readily recycled by short-duration high temperature air oxidation to remove residual analyte molecules in repeated runs. The limiting factor associated with the thermal oxidation recycling process was the Ostwald ripening effect of Ag nanostructures.

  9. The spatial and energy dependence of gold nanoparticle dose enhancement using deterministic computations

    Science.gov (United States)

    Cifter, Fulya

    The main objective of this work is to investigate the detailed dose enhancement characteristics of Gold Nanoparticle Aided Radiotherapy using deterministic computations, which offer several advantages over Monte Carlo simulations. In the first chapter, computations were preformed to obtain the parametric representation of gold nanoparticle (GNP) dose enhancement as function of space and incident photon energy, which can be regarded as the Green's function of GNP aided radiotherapy. The Green's function describes the spatial distribution of dose response in water due to a specific photon energy incident on single or clustered GNPs of defined size, located at a given depth in the phantom. In this way, using convolution-superposition, the dose enhancement may be determined for any incident photon spectrum and combinations of GNP sizes and depths. In obtaining the parameterized Green's function, dose enhancement as function of incident energy, GNP size, and GNP depth was calculated at nanometric spatial resolution for a series of monoenergetic beams. In addition, the dose enhancement was also determined for clinical beams in which the incident photon spectra were obtained using Monte Carlo. Based on the systematic computations of DER as function of x-ray energy and GNP size, optimal photon energies and optimal GNP sizes were determined. In the second chapter, dosimetric properties of GNP-laden target volumes (TV) embedded in a water phantom were investigated as a function of GNP concentration, geometry, and volume. In addition, the characteristics of GNP dose enhancement due to clustering versus homogeneous concentrations are studied. These parameters have importance in today's sophisticated beam delivery techniques, when modifying the beam intensity and direction provides a conformal dose delivery during treatment. Coupled electron-photon radiation transport computations were performed in high spatial resolution (1 nm -- 10 mum mesh sizes) using the CEPXS/ONEDANT code

  10. A Long-Wavelength Fluorescent Squarylium Cyanine Dye Possessing Boronic Acid for Sensing Monosaccharides and Glycoproteins with High Enhancement in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Hiroyuki Nakazumi

    2012-04-01

    Full Text Available Fluorescence sensing of saccharides and glycoproteins using a boronic acid functionalized squarylium cyanine dye (“SQ-BA” is characterized in terms of synthetic, fluorometric, thermodynamic and kinetic parameters. In our previous work, this newly synthesized dye was successfully applied to the separation and quantification of Gram-positive bacteria by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF; however, the fundamental properties of the dye and its saccharide complexes still required elucidation, as presented in this paper. The dye itself forms nonemissive, soluble aggregates in aqueous solution. With the addition of a monosaccharide, the dye aggregate dissociates to form an emissive monomer accompanied by the formation of a cyclic cis-diol ester with long-wavelength emission (lex = 630 nm, lem = 660 nm. A very large fluorescence enhancement factor of 18× was observed for the sensing dye as a fructose complex at pH 10, yielding a limit of detection of 10 mM fructose. The relative order of fluorescence enhancement of SQ-BA with other monosaccharides was found to be: fructose > ribose > arabinose ≈ galactose > xylose > mannose > rhamnose > fucose ≈ glucose; and apparent affinity constants of 102.80, 102.08 and 100.86 M−1 were determined for fructose, ribose and glucose, respectively. Formation of the emissive complexes occurred within minutes, proving the kinetics of the sugar-dye interactions to be suitable for on-column labeling methods in CE-LIF. Furthermore, the sensing dye was successfully applied to glycoproteins, mucin type I–S and type III, which were detected with high sensitivity in batch aqueous solution as a result of the sugar-selective boronic acid-diol esterification as well as hydrophobic interactions.

  11. Investigation of carbon profiles for enhanced boron confinement and improved carrier transport in strained silicon germanium nanolayers for heterojunction bipolar transistors

    Science.gov (United States)

    Enicks, Darwin Gene

    increases base recombination current, while reducing the built-in biaxial strain. This latter property may or may not be desirable, while the first two are not desirable having negative consequences for fmax and noise figures of merit such as NF min. Chapter 8 discusses portions of this research, which identified a first-to-be-published method for carbon doping of silicon germanium films, which enhances the carbon confinement of boron, significantly reduces film resistance by approximately 23%, and increases the NPN HBT device performance. Chapter 9 discusses the improvements in noise figures of merit for an NPN HBT, which arise from improved film qualities presented in the Chapter 8 discussion. This research also illustrates that the device performance figures of merit such as base resistance, current gain, and subsequent noise figures are significantly determined during the epitaxial film growth.

  12. Enhanced selectivity of boron doped diamond electrodes for the detection of dopamine and ascorbic acid by increasing the film thickness

    Science.gov (United States)

    Qi, Yao; Long, Hangyu; Ma, Li; Wei, Quiping; Li, Site; Yu, Zhiming; Hu, Jingyuan; Liu, Peizhi; Wang, Yijia; Meng, Lingcong

    2016-12-01

    In this paper, boron doped diamond (BDD) with different thickness were prepared by hot filament chemical vapor deposition. The performance of BDD electrodes for detecting dopamine (DA) and ascorbic acid (AA) were investigated. Scanning electron microscopy and Raman spectra reveal the grain size increases and the film quality improves with the increase of film thickness. Electrochemical test show that the transfer coefficient in [Fe3 (CN) 6]3-/4- redox system increases with the increase of the film thickness. The results of selectivity and sensitivity for DA mixed with AA detection show that 8h-BDD and 12h-BDD electrodes possess well selective separated oxidation peaks of DA and AA, and the 12h-BDD electrode exhibits optimal sensitivity until the DA concentration drops to 1 μ M.

  13. Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays.

    Science.gov (United States)

    Zygmanski, Piotr; Sajo, Erno

    2016-01-01

    We review radiation transport and clinical beam modelling for gold nanoparticle dose-enhanced radiotherapy using X-rays. We focus on the nanoscale radiation transport and its relation to macroscopic dosimetry for monoenergetic and clinical beams. Among other aspects, we discuss Monte Carlo and deterministic methods and their applications to predicting dose enhancement using various metrics.

  14. On-column labeling of gram-positive bacteria with a boronic acid functionalized squarylium cyanine dye for analysis by polymer-enhanced capillary transient isotachophoresis.

    Science.gov (United States)

    Saito, Shingo; Massie, Tara L; Maeda, Takeshi; Nakazumi, Hiroyuki; Colyer, Christa L

    2012-03-06

    A new asymmetric, squarylium cyanine dye functionalized by boronic acid ("SQ-BA") was designed and synthesized for on-capillary labeling of gram-positive bacteria to provide for high sensitivity detection by way of a modified form of capillary electrophoresis with laser induced fluorescence detection (CE-LIF). The CE-based separation employed a polymer-enhanced buffer with capillary transient isotachophoresis in a new hybrid method dubbed "PectI." It was found that the addition of various monosaccharides to SQ-BA in a batch aqueous solution greatly enhanced the emission of the boronic acid functionalized dye by a factor of up to 18.3 at a long wavelength (λ(ex) = 630 nm, λ(em) = 660 nm) with a high affinity constant (K = ~10(2.80) M(-1)) superior to other sugar probes. Semiempirical quantum mechanics calculations suggest that the mechanism for this high enhancement may involve the dissociation of initially nonemissive dye associates (stabilized by an intramolecular hydrogen bond) upon complex formation with sugars. The fluorescence emission of SQ-BA was also significantly enhanced in the presence of a gram-positive bacterial spore, Bacillus globigii (Bg), which serves as a simulant of B. anthracis (or anthrax) and which possesses a peptidoglycan (sugar)-rich spore coat to provide ample sites for interaction with the dye. Several peaks were observed for a pure Bg sample even with polyethyleneoxide (PEO) present in the CE separation buffer, despite the polymer's previously demonstrated ability to focus microoorganisms to a single peak during migration. Likewise, several peaks were observed for a Bg sample when capillary transient isotachophoresis (ctITP) alone was employed. However, the new combination of these techniques as "PectI" dramatically and reproducibly focused the bacteria to a single peak with no staining procedure. Using PectI, the trace detection of Bg spores (corresponding to approximately three cells per injection) along with separation efficiency

  15. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-04

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

  16. Doses de boro e crescimento radicular e da parte aérea de cultivares de arroz de terras altas Influence of boron addition on growth of roots and shoot of upland rice crops

    Directory of Open Access Journals (Sweden)

    Juliano Corulli Corrêa

    2006-12-01

    Full Text Available O crescimento radicular é favorecido em condições adequadas de disponibilidade de boro no solo e, por isto, a aplicação da dose correta desse micronutriente é de grande importância, para que não ocorra prejuízo no desenvolvimento e na produtividade da cultura de arroz de terras altas, de acordo com a variedade e tipo de solo. O presente trabalho teve como objetivo avaliar a influência das doses de boro no crescimento radicular e da parte aérea, em três cultivares de arroz de terras altas. O experimento foi realizado em casa de vegetação, em vaso com capacidade de 10 L, que continha 8 dm³ de solo Latossolo Vermelho distrófico, sendo o delineamento experimental inteiramente casualizado, em esquema fatorial 3 x 3, com quatro repetições. Os tratamentos consistiram de três cultivares (Caiapó, Primavera e Maravilha e três doses de boro (0, 3 e 6 mg dm-3, usando, como fonte, o bórax. A dose de 6 mg dm-3 foi prejudicial tanto à produção de matéria seca da parte aérea como de raiz para o arroz de terras altas. Além de apresentar maior capacidade de absorção de boro, o cultivar Maravilha apresentou-se mais tolerante à elevação da disponibilidade de B no solo, não ocorrendo alterações de comprimento, diâmetro e superfície radicular.Appropriate boron (B availability in soils favors root growth, and a sufficient supply of this micronutrient is very important for adequate rice development and yield in upland fields, depending on the cultivars and soil type. This study aimed at evaluating the influence of B addition on growth of roots and shoot of three upland rice cultivars. The experiment was carried out in a greenhouse, in 10 L pots containing 8 kg of an Hapludox; the experiment was in a completely random 3 x 3 factorial design, with four replications. The treatments consisted of three rice cultivars (Caiapó, Primavera, and Maravilha and three B rates (0, 3 and 6 mg dm-3, as borax. The B rate of 6 mg dm-3 boron was

  17. Low Doses of Ethanol Enhance LTD-like Plasticity in Human Motor Cortex.

    Science.gov (United States)

    Fuhl, Anna; Müller-Dahlhaus, Florian; Lücke, Caroline; Toennes, Stefan W; Ziemann, Ulf

    2015-12-01

    Humans liberally use ethanol for its facilitating effects on social interactions but its effects on central nervous system function remain underexplored. We have recently described that very low doses of ethanol abolish long-term potentiation (LTP)-like plasticity in human cortex, most likely through enhancement of tonic inhibition [Lücke et al, 2014, Neuropsychopharmacology 39:1508-18]. Here, we studied the effects of low-dose ethanol on long-term depression (LTD)-like plasticity. LTD-like plasticity was induced in human motor cortex by paired associative transcranial magnetic stimulation (PASLTD), and measured as decreases of motor evoked potential input-output curve (IO-curve). In addition, sedation was measured by decreases in saccade peak velocity (SPV). Ethanol in two low doses (EtOHethanol, easily reached during social drinking, enhance LTD-like plasticity in human cortex. This effect is most likely explained by the activation of extrasynaptic α4-subunit containing gamma-aminobutyric type A receptors by low-dose EtOH, resulting in increased tonic inhibition. Findings may stimulate cellular research on the role of tonic inhibition in regulating excitability and plasticity of cortical neuronal networks.

  18. Boron remobilization at low boron supply in olive (Olea europaea) in relation to leaf and phloem mannitol concentrations.

    Science.gov (United States)

    Liakopoulos, Georgios; Stavrianakou, Sotiria; Filippou, Manolis; Fasseas, Costas; Tsadilas, Christos; Drossopoulos, Ioannis; Karabourniotis, George

    2005-02-01

    For plant species in which a considerable portion of the photoassimilates are translocated in the phloem as sugar alcohols, boron is freely translocated from mature organs to growing tissues. However, the effects of decreased plant boron status on boron remobilization are poorly understood. We conducted a growth chamber experiment (CE) and a field experiment (FE) to study the effects of low boron supply on boron remobilization in olive (Olea europaea L.), a species that transports considerable amounts of mannitol in the phloem. For the CE, several physiological parameters were compared between control (B+) and boron-deficient olive plants (B-) during the expansion of new leaves. Boron remobilization was assessed by measuring boron content of selected leaves at the beginning and at the end of the CE. As expected, boron was remobilized from mature leaves to young leaves of B+ plants; however, considerable boron remobilization was also observed in B- plants, suggesting a mechanism whereby olive can sustain a minimum boron supply for growth of new tissues despite an insufficient external boron supply. Boron deficiency caused inhibition of new growth but had no effect on photosynthetic capacity per unit leaf surface area of young and mature leaves, thereby altering the carbon utilization pattern and resulting in carbon allocation to structures within the source leaves and accumulation of soluble carbohydrates. Specifically, in mature B- leaves in the CE and in B- leaves in the FE, mannitol concentration on a leaf water content basis increased by 48 and 27% respectively, compared with controls. Carbon export ability (assessed by both phloem anatomy and phloem exudate composition of FE leaves) was enhanced at low boron supply. We conclude that, at low boron supply, increased mannitol concentrations maintain boron remobilization from source leaves to boron-demanding sink leaves.

  19. Yield and fruit of papaya ‘sunrise solo’ as function of doses of nitrogen and boron/ Produtividade e qualidade de frutos de mamoeiro ‘sunrise solo’ em função de doses de nitrogênio e boro

    Directory of Open Access Journals (Sweden)

    Raunira da Costa Araújo

    Full Text Available The study aimed to evaluate the yield and fruit quality of papaya ‘Sunrise Solo’ as function of nitrogen and boron fertilization. The experiment had a randomized block design with four replications, two plants per plot with a single border. To make up the treatments, we used the experimental array Plan Puebla III, which set the rates for nitrogen (0.0 to 111.2 - 200 – 288.9 - 400 g plant-1, and B (0.0 – 0.83 - 1.5 – 2.16 - 3.0 g plant-1, in a total of ten treatments. The addition of nitrogen increased the yield, average fruit weight and number of fruits per plant. The nitrogen and boron increased the diameter and length of the fruit, amount of seeds and content of soluble solids. The pH of the pulp decreased linearly with increasing doses of nitrogen and boron. It was observed a significant effect of N rates on the level of vitamin C.O trabalho teve como objetivo avaliar a produtividade e a qualidade de frutos de mamoeiro ‘Sunrise Solo’ em função de doses de nitrogênio e boro. O trabalho foi desenvolvido na fazenda Chan de Jardim no Centro de Ciências Agrárias–UFPB no Município de Areia, em um solo de textura areno-argilosa classificado como Neossolo Regolítico. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições e duas plantas úteis por parcela com bordadura simples. Para a composição dos tratamentos, utilizou-se a matriz experimental Plan Puebla III, onde se definiram as doses para nitrogênio (0,0 - 111,2 – 200 – 288,9 – 400 g planta-1, e para boro (0,0 - 0,83 - 1,5 - 2,16 - 3,0 g planta-1, totalizando dez tratamentos. A adição de nitrogênio aumentou a produtividade, o peso médio dos frutos e o número de frutos por planta. As doses de nitrogênio e boro aumentaram o diâmetro e comprimento do fruto, rendimento de semente e teor de sólidos solúveis totais. O pH da polpa decresceu linearmente com o aumento das doses de N e de boro. Houve efeito significativo das

  20. Boron Nitride Nanotubes

    Science.gov (United States)

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

    2012-01-01

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

  1. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-21

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

  2. Tetraploidy enhances boron-excess tolerance in Carrizo Citrange (Citrus sinensis L. Osb. x Poncirus trifoliata L. Raf.

    Directory of Open Access Journals (Sweden)

    Marta eRuiz

    2016-05-01

    Full Text Available Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B toxicity responses in diploid (2x and tetraploid (4x plants of Carrizo citrange (Citrus sinensis L. Osb. x Poncirus trifoliata L. Raf., a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport.

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  4. Methods of forming boron nitride

    Science.gov (United States)

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

    2015-03-03

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

  5. Size Effects of Gold and Iron Nanoparticles on Radiation Dose Enhancement in Brachytherapy and Teletherapy: A Monte Carlo Study

    Directory of Open Access Journals (Sweden)

    Ahad Ollah Ezzati

    2014-08-01

    Full Text Available Introduction In this study, we aimed to calculate dose enhancement factor (DEF for gold (Au and iron (Fe nanoparticles (NPs in brachytherapy and teletherapy, using Monte Carlo (MC method. Materials and Methods In this study, a new algorithm was introduced to calculate dose enhancement by AuNPs and FeNPs for Iridium-192 (Ir-192 brachytherapy and Cobalt-60 (Co-60 teletherapy sources, using the MC method. In this algorithm, the semi-random distribution of NPs was used instead of the regular distribution. Diameters were assumed to be 15, 30, and 100 nm in brachytherapy and 15 and 30 nm in teletherapy. Monte Carlo MCNP4C code was used for simulations, and NP density values were 0.107 mg/ml and 0.112 mg/ml in brachytherapy and teletherapy, respectively. Results AuNPs significantly enhanced the radiation dose in brachytherapy (approximately 60%, and 100 nm diameter NPs showed the most uniform dose distribution. AuNPs had an insignificant effect on teletherapy radiation field, with a dose enhancement ratio of 3% (about the calculation uncertainty or less. In addition, FeNPs had an insignificant effect on both brachytherapy and teletherapy radiation fields. FeNPs dose enhancement was 3% in brachytherapy and 6% (about the calculation uncertainty or less in teletherapy. Conclusion It can be concluded that AuNPs can significantly increase the absorbed dose in brachytherapy; however, FeNPs do not have a noticeable effect on the absorbed dose

  6. 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.

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

    Science.gov (United States)

    Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar

    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.

  8. Low-dose non-enhanced CT versus full-dose contrast-enhanced CT in integrated PET/CT studies for the diagnosis of uterine cancer recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Kitajima, Kazuhiro [Institute of Biomedical Research and Innovation, Department of PET Diagnosis, Kobe (Japan); Kobe University Graduate School of Medicine, Department of Radiology, Kobe (Japan); Suzuki, Kayo [Institute of Biomedical Research and Innovation, Department of PET Diagnosis, Kobe (Japan); Nakamoto, Yuji [Kyoto University Hospital, Department of Diagnostic Radiology, Kyoto (Japan); Onishi, Yumiko; Sakamoto, Setsu; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Department of Radiology, Kobe (Japan); Senda, Michio [Institute of Biomedical Research and Innovation, Department of Molecular Imaging, Kobe (Japan); Kita, Masato [Kobe City Medical Center General Hospital, Department of Obstetrics and Gynecology, Kobe (Japan)

    2010-08-15

    To evaluate low-dose non-enhanced CT (ldCT) and full-dose contrast-enhanced CT (ceCT) in integrated {sup 18}F-fluorodeoxyglucose (FDG) PET/CT studies for restaging of uterine cancer. A group of 100 women who had undergone treatment for uterine cervical (n=55) or endometrial cancer (n=45) underwent a conventional PET/CT scans with ldCT, and then a ceCT scan. Two observers retrospectively reviewed and interpreted the PET/ldCT and PET/ceCT images in consensus using a three-point grading scale (negative, equivocal, or positive) per patient and per lesion. Final diagnoses were obtained by histopathological examination, or clinical follow-up for at least 6 months. Patient-based analysis showed that the sensitivity, specificity and accuracy of PET/ceCT were 90% (27/30), 97% (68/70) and 95% (95/100), respectively, whereas those of PET/ldCT were 83% (25/30), 94% (66/70) and 91% (91/100), respectively. Sensitivity, specificity and accuracy did not significantly differ between two methods (McNemar test, p=0.48, p=0.48, and p=0.13, respectively). There were 52 sites of lesion recurrence: 12 pelvic lymph node (LN), 11 local recurrence, 8 peritoneum, 7 abdominal LN, 5 lung, 3 supraclavicular LN, 3 liver, 2 mediastinal LN, and 1 muscle and bone. The grading results for the 52 sites of recurrence were: negative 5, equivocal 0 and positive 47 for PET/ceCT, and negative 5, equivocal 4 and positive 43 for PET/ldCT, respectively. Four equivocal regions by PET/ldCT (local recurrence, pelvic LN metastasis, liver metastasis and muscle metastasis) were correctly interpreted as positive by PET/ceCT. PET/ceCT is an accurate imaging modality for the assessment of uterine cancer recurrence. Its use reduces the frequency of equivocal interpretations. (orig.)

  9. SU-E-T-44: Angular Dependence of Surface Dose Enhancement Measured On Several Inhomogeneities Using Radiochromic EBT3 Films

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, A; Schoenfeld, A; Poppinga, D; Chofor, N; Poppe, B [University of Oldenburg, Oldenburg (Germany); Pius Hospital Oldenburg, Oldenburg (Germany)

    2014-06-01

    Purpose: The quantification of the relative surface dose enhancement in dependence on the angle of incidence and the atomic number Z of the surface material. Methods: Experiments were performed with slabs made of aluminum, titanium, copper, silver, dental gold and lead. The metal slabs with equal sizes of 1.0×8.0×8.8mm{sup 3} were embedded in an Octavius 4D phantom (PTW Freiburg, Germany). Radiochromic EBT3 films were used to measure the surface dose for angles of incidence ranging from 0° to 90°. The setup with the metals slabs at the isocenter was irradiated with acceleration voltages of 6MV and 10MV. Water reference measurements were taken under equal conditions. Results: The surface dose enhancement is highest for angles of incidence below 30° and drops significantly for higher. The surface dose enhancement produced by lead and dental gold at 6MV showed a peak of 65%. At 90°, the surface dose enhancement dropped to 15% for both materials. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 32%, 22% and 12% at 0°, respectively. At an angle of incidence of 80°, the values dropped to 22%, 18%, 12% und 6%. The values for 10MV were very similar. Lead and dental gold showed peaks of 65% und 60%. Their values dropped to 18% at an angle of 90°. The surface dose enhancements for silver, copper, titanium and aluminum were 45%, 30%, 20% and 8% at 0°. At 80° the values dropped to 30%, 20%, 12% and 5%. A dependence of the magnitude of the surface dose enhancement on the atomic number of the surface material can be seen, which is in consistence with literature. Conclusion: The results show that the surface dose enhancements near implant materials with high Z-values should be taken into consideration in radio therapy, even when the angle of incidence is flat.

  10. Vascular changes caused by deep brain stimulation using double-dose gadolinium-enhanced brain MRI

    Institute of Scientific and Technical Information of China (English)

    Byeong Sam Choi; Yong Hwan Kim; Sang Ryong Jeon

    2014-01-01

    We retrospectively analyzed the clinical data of 32 patients with medically intractable idiopathic Parkinson’s disease who had undergone staged bilateral deep brain stimulation of the subtha-lamic nuclei from January 2007 to May 2011. The vascularture of the patients who received two deep brain stimulations was detected using double-dose gadolinium-enhanced brain MRI. The dimensions of straight sinus, superior sagittal sinus, ipsilateral internal cerebral vein in the tha-lamic branch and ipsilateral anterior caudate vein were reduced. These ifndings demonstrate that bilateral deep brain stimulation of the subthalamic nuclei affects cerebral venous blood lfow.

  11. Nanoparticle-Enabled Transdermal Drug Delivery Systems for Enhanced Dose Control and Tissue Targeting

    Directory of Open Access Journals (Sweden)

    Brian C. Palmer

    2016-12-01

    Full Text Available Transdermal drug delivery systems have been around for decades, and current technologies (e.g., patches, ointments, and creams enhance the skin permeation of low molecular weight, lipophilic drugs that are efficacious at low doses. The objective of current transdermal drug delivery research is to discover ways to enhance skin penetration of larger, hydrophilic drugs and macromolecules for disease treatment and vaccination. Nanocarriers made of lipids, metals, or polymers have been successfully used to increase penetration of drugs or vaccines, control drug release, and target drugs to specific areas of skin in vivo. While more research is needed to identify the safety of nanocarriers, this technology has the potential to expand the use of transdermal routes of administration to a wide array of therapeutics. Here, we review the current state of nanoparticle skin delivery systems with special emphasis on targeting skin diseases.

  12. Boron neutron capture therapy: Moving toward targeted cancer therapy

    Directory of Open Access Journals (Sweden)

    Hamid Reza Mirzaei

    2016-01-01

    Full Text Available Boron neutron capture therapy (BNCT occurs when a stable isotope, boton-10, is irradiated with low-energy thermal neutrons to yield stripped down helium-4 nuclei and lithium-7 nuclei. It is a binary therapy in the treatment of cancer in which a cytotoxic event is triggered when an atom placed in a cancer cell. Here, we provide an overview on the application of BNCT in cancer therapy as well as current preclinical and clinical evidence on the efficacy of BNCT in the treatment of melanoma, brain tumors, head and neck cancer, and thyroid cancer. Several studies have shown that BNCT is effective in patients who had been treated with a full dose of conventional radiotherapy, because of its selectivity. In addition, BNCT is dependent on the normal/tumor tissue ratio of boron distribution. Increasing evidence has shown that BNCT can be combined with different drug delivery systems to enhance the delivery of boron to cancer cells. The flexibility of BNCT to be used in combination with different tumor-targeting approaches has made this strategy a promising option for cancer therapy. This review aims to provide a state-of-the-art overview of the recent advances in the use of BNCT for targeted therapy of cancer.

  13. CTA-enhanced perfusion CT: an original method to perform ultra-low-dose CTA-enhanced perfusion CT

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Elizabeth; Wintermark, Max [University of Virginia, Department of Radiology, Neuroradiology Division, Charlottesville, VA (United States)

    2014-11-15

    Utilizing CT angiography enhances image quality in PCT, thereby permitting acquisition at ultra-low dose. Dynamic CT acquisitions were obtained at 80 kVp with decreasing tube current-time product [milliamperes x seconds (mAs)] in patients suspected of ischemic stroke, with concurrent CTA of the cervical and intracranial arteries. By utilizing fast Fourier transformation, high spatial frequencies of CTA were combined with low spatial frequencies of PCT to create a virtual PCT dataset. The real and virtual PCT datasets with decreasing mAs were compared by assessing contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and noise and PCT values and by visual inspection of PCT parametric maps. Virtual PCT attained CNR and SNR three- to sevenfold superior to real PCT and noise reduction by a factor of 4-6 (p < 0.05). At 20 mAs, virtual PCT achieved diagnostic parametric maps, while the quality of real PCT maps was inadequate. At 10 mAs, both real and virtual PCT maps were nondiagnostic. Virtual PCT (but not real PCT) maps regained diagnostic quality at 10 mAs by applying 40 % adaptive statistical iterative reconstruction (ASIR) and improved further with 80 % ASIR. Our new method of creating virtual PCT by combining ultra-low-dose PCT with CTA information yields diagnostic perfusion parametric maps from PCT acquired at 20 or 10 mAs with 80 % ASIR. Effective dose is approximately 0.20 mSv, equivalent to two chest radiographs. (orig.)

  14. The impact of dosing interval in a novel tandem oral dosing strategy: enhancing the exposure of low solubility drug candidates in a preclinical setting.

    Science.gov (United States)

    Chiang, Po-Chang; South, Sarah A; Wene, Steve P

    2011-01-01

    In drug discovery, time and resource constraints necessitate increasingly early decision making to accelerate or stop preclinical programs. Early discovery drug candidates may be potent inhibitors of new targets, but all too often exhibit poor pharmaceutical or pharmacokinetic properties that limit the in vivo exposure. Low solubility of a drug candidate often leads to poor oral bioavailability and poor dose linearity. This issue is more significant for efficacy and target safety studies where high drug exposures are desired. When solubility issues are confronted, enabling formulations are often required to improve the exposure. However, this approach often requires a substantial and lengthy investment to develop the formulation. Previously, we introduced a gastrointestinal (GI) transit time-based novel oral tandem dosing strategy that enhanced in vivo exposures in rats. In this study, a refined time interval versus dose theory was tested. The resulting in vivo exposures based on altering frequency and doses were compared, and significant impacts were found.

  15. The Impact of Dosing Interval in a Novel Tandem Oral Dosing Strategy: Enhancing the Exposure of Low Solubility Drug Candidates in a Preclinical Setting

    Directory of Open Access Journals (Sweden)

    Po-Chang Chiang

    2011-01-01

    Full Text Available In drug discovery, time and resource constraints necessitate increasingly early decision making to accelerate or stop preclinical programs. Early discovery drug candidates may be potent inhibitors of new targets, but all too often exhibit poor pharmaceutical or pharmacokinetic properties that limit the in vivo exposure. Low solubility of a drug candidate often leads to poor oral bioavailability and poor dose linearity. This issue is more significant for efficacy and target safety studies where high drug exposures are desired. When solubility issues are confronted, enabling formulations are often required to improve the exposure. However, this approach often requires a substantial and lengthy investment to develop the formulation. Previously, we introduced a gastrointestinal (GI transit time-based novel oral tandem dosing strategy that enhanced in vivo exposures in rats. In this study, a refined time interval versus dose theory was tested. The resulting in vivo exposures based on altering frequency and doses were compared, and significant impacts were found.

  16. Simulation study of dose enhancement in a cell due to nearby carbon and oxygen in particle radiotherapy

    CERN Document Server

    Shin, Jae Ik; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Jung, Won-Gyun; Yoo, SeungHoon; Shin, Dongho; Lee, Se Byeong; Yoon, Myonggeun; Incerti, Sebastian; Geso, Moshi; Rosenfeld, Anatoly B

    2015-01-01

    The aim of this study is to investigate the dose-deposition enhancement by alpha-particle irradiation in a cellular model using carbon and oxygen chemical compositions.A simulation study was performed to study dose enhancement due to carbon and oxygen for a human cell where Geant4 code used for the alpha-particle irradiation to the cellular phantom. The characteristic of dose enhancement in the nucleus and cytoplasm by the alpha-particle radiation was investigated based on concentrations of the carbon and oxygen compositions and was compared with those by gold and gadolinium.The results show that both the carbon and oxygen-induced dose enhancement was found to be more effective than those of gold and gadolinium. We found that the dose-enhancement effect was more dominant in the nucleus than in the cytoplasm if carbon or oxygen is uniformly distributed in a whole cell. In the condition that the added chemical composition was inserted only into the cytoplasm, the effect of the dose enhancement in nucleus become...

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

    Science.gov (United States)

    Jung, Joo-Young; Yoon, Do-Kun; Lee, Heui Chang; Lu, Bo; Suh, Tae Suk

    2016-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Joo-Young Jung

    2016-09-01

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

  19. Boron nitride converted carbon fiber

    Science.gov (United States)

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

    2016-04-05

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

  20. Crescimento de soja em solos em resposta a doses de Boro, calagem e textura do solo Soybean growth in response to boron dosages, liming and soil texture

    Directory of Open Access Journals (Sweden)

    Rodinei Facco Pegoraro

    2008-08-01

    Full Text Available Neste trabalho, objetivou-se quantificar a produção de matéria seca e os conteúdos de B, Ca e Mg na cultura da soja cultivada em solos com diferentes texturas que receberam doses crescentes de B e calagem, e correlacionar o conteúdo de B absorvido pela planta com o teor de B recuperado com água e CaCl2 ferventes sob influência de doses de boro e a calagem aplicadas em três solos distintos. O experimento foi conduzido em casa de vegetação em esquema fatorial 3 x 2 x 6, consistindo de três solos: textura arenosa (RQ, textura média (LVA1 e textura argilosa (LVA2, com e sem calagem, e seis doses de B (0; 1,5; 3; 6; 9 e 15 mg dm-3, em blocos casualizados com três repetições. Determinou-se o teor de B no solo extraível com água e CaCl2 ferventes após 45 dias da adição das doses de B aos solos, massa de matéria seca da parte aérea e os teores de B, Ca e Mg na soja. Os teores de B recuperado, tanto pela água fervente, quanto pelo CaCl2 fervente foram semelhantes nos três solos estudados e, apresentaram altas correlações com o conteúdo de B e o peso de matéria seca. As doses de B adicionadas aumentaram a sua absorção pelas plantas, mas causaram redução na produção de matéria seca da parte aérea nos solos RQ (textura arenosa, LVA1 (textura média e o LVA2 (textura argilosa com calagem, neste último solo, o efeito é minimizado na presença de maior teor de argila.This work aimed to quantify the dry matter production and the contents of B, Ca and Mg in soybean plants grown in soils with different textures, which received increasing doses of B, and liming. Additionally, it was correlated the B contents in the plants with the B recovered from the soil with boiling water and CaCl2. The experiment was carried out in a greenhouse in a factorial 3 x 2 x 6 (three soils: sand texture (RQ, loamy sand (LVA1 and clayey (LVA2 textures; with and without liming; and six B doses: 0; 1,5; 3; 6; 9 and 15 mg dm-3 arranged in a entirely

  1. Enhanced aflatoxin production by aspergillus parasiticus and aspergillus flavus after low dose gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hitoshi (Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment)

    1992-09-01

    Spores of Aspergillus parasiticus IFO 30179 and A. flavus var. columnaris S46 were irradiated at 0.05, 0.2 and 0.4 kGy in the synthetic low salts (SL) broth, and the effect on aflatoxin production was examined after 10 days incubation at 30 or 25degC. In these two strains, irradiation of spores at 0.05 kGy resulted in higher B1 or G1 production than the non-irradiated controles. However, spores of the both strains irradiated at 0.2 or 0.4 kGy produced less aflatoxins than non-irradiated controles. In the SL broth, apparent stimulation by low dose irradiation was slight, and these enhanced effects were not observed after reinfection to fresh SL broth. In the case of food samples, the levels of aflatoxin B[sub 1] and G[sub 1] with A. parasiticus were increased from 15 to 90% by incubation of irradiated spores at 1 kGy in autoclaved polished rice, black pepper, white pepper and red pepper. These enhancement would be induced by change of composition in each substrates. Mutations of fungi induced by irradiation is not effective for enhancement of aflatoxin production. (author).

  2. A Monte Carlo study of I-125 prostate brachytherapy with gold nanoparticles: dose enhancement with simultaneous rectal dose sparing via radiation shielding

    Science.gov (United States)

    Brivio, D.; Nguyen, P. L.; Sajo, E.; Ngwa, W.; Zygmanski, P.

    2017-03-01

    We investigate via Monte Carlo simulations a new 125I brachytherapy treatment technique for high-risk prostate cancer patients via injection of Au nanoparticle (AuNP) directly into the prostate. The purpose of using the nanoparticles is to increase the therapeutic index via two synergistic effects: enhanced energy deposition within the prostate and simultaneous shielding of organs at risk from radiation escaping from the prostate. Both uniform and non-uniform concentrations of AuNP are studied. The latter are modeled considering the possibility of AuNP diffusion after the injection using brachy needles. We study two extreme cases of coaxial AuNP concentrations: centered on brachy needles and centered half-way between them. Assuming uniform distribution of 30 mg g‑1 of AuNP within the prostate, we obtain a dose enhancement larger than a factor of 2 to the prostate. Non-uniform concentration of AuNP ranging from 10 mg g‑1 and 66 mg g‑1 were studied. The higher the concentration in a given region of the prostate the greater is the enhancement therein. We obtain the highest dose enhancement when the brachytherapy needles are coincident with AuNP injection needles but, at the same time, the regions in the tail are colder (average dose ratio of 0.7). The best enhancement uniformity is obtained with the seeds in the tail of the AuNP distribution. In both uniform and non-uniform cases the urethra and rectum receive less than 1/3 dose compared to an analog treatment without AuNP. Remarkably, employing AuNP not only significantly increases dose to the target but also decreases dose to the neighboring rectum and even urethra, which is embedded within the prostate. These are mutually interdependent effects as more enhancement leads to more shielding and vice-versa. Caution must be paid since cold spot or hot spots may be created if the AuNP concentration versus seed position is not properly distributed respect to the seed locations.

  3. Improvement effect on the depth-dose distribution by CSF drainage and air infusion of a tumour-removed cavity in boron neutron capture therapy for malignant brain tumours

    Science.gov (United States)

    Sakurai, Yoshinori; Ono, Koji; Miyatake, Shin-ichi; Maruhashi, Akira

    2006-03-01

    Boron neutron capture therapy (BNCT) without craniotomy for malignant brain tumours was started using an epi-thermal neutron beam at the Kyoto University Reactor in June 2002. We have tried some techniques to overcome the treatable-depth limit in BNCT. One of the effective techniques is void formation utilizing a tumour-removed cavity. The tumorous part is removed by craniotomy about 1 week before a BNCT treatment in our protocol. Just before the BNCT irradiation, the cerebro-spinal fluid (CSF) in the tumour-removed cavity is drained out, air is infused to the cavity and then the void is made. This void improves the neutron penetration, and the thermal neutron flux at depth increases. The phantom experiments and survey simulations modelling the CSF drainage and air infusion of the tumour-removed cavity were performed for the size and shape of the void. The advantage of the CSF drainage and air infusion is confirmed for the improvement in the depth-dose distribution. From the parametric surveys, it was confirmed that the cavity volume had good correlation with the improvement effect, and the larger effect was expected as the cavity volume was larger.

  4. Doped Boron Carbide-Based Polymers: Fundamental Studies of a Novel Class of Materials for Enhanced Neutron Detection

    Science.gov (United States)

    2016-03-01

    field of 0 T (black line), 0.1 T (purple line), 0.5 T (blue line), 0.8 T (green line) and 1 T (red line) for thin films of cross -linked ortho...aromatic precursors in UHV followed by electron bombardment to induce cross -linking, and (b) plasma-enhanced chemical vapor deposition (PECVD) of films...electronic structure. 3. Diode Detector Formation and testing: Diode structures were assembled from PECVD of ortho-carborane/aromatic films (p-type

  5. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    Energy Technology Data Exchange (ETDEWEB)

    Sulyaeva, Veronica S., E-mail: veronica@niic.nsc.ru [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A. [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, Valerii G. [Laboratory of Physical Principles for Integrated Microelectronics, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Kirienko, Viktor V. [Laboratory of Nonequilibrium Semiconductors Systems, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation)

    2014-05-02

    Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers (93%). • BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9.

  6. Low dose creatine supplementation enhances sprint phase of 400 meters swimming performance.

    Science.gov (United States)

    Anomasiri, Wilai; Sanguanrungsirikul, Sompol; Saichandee, Pisut

    2004-09-01

    This study demonstrated the effect of low dose creatine supplement (10 g. per day) on the sprinting time in the last 50 meters of 400 meters swimming competition, as well as the effect on exertion. Nineteen swimmers in the experimental group received creatine monohydrate 5 g with orange solution 15 g, twice per day for 7 days and nineteen swimmers in the control group received the same quantity of orange solution. The results showed that the swimmers who received creatine supplement lessened the sprinting time in the last 50 meters of 400 meters swimming competition than the control group. (pcreatine supplement in the experiment group. Therefore, the creatine supplement in amateur swimmers in the present study enhanced the physical performance up to the maximum capacity.

  7. Studying Effects of Gold Nanoparticle on Dose Enhancement in Megavoltage Radiation

    Science.gov (United States)

    Khadem Abolfazli, M.; Mahdavi, S. R.; Ataei, Gh.

    2015-01-01

    Background Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. Objective The aim of this study is to understand characteristics of secondary electrons generated from interaction of gold nanoparticles GNPs with x-rays as a function of nanoparticle size and beam energy and thereby further understanding of GNP-enhanced radiotherapy. Methods Effective range, defection angle, dose deposition, energy, and interaction processes of electrons produced from the interaction of x-rays with a GNP were calculated by Monte Carlo simulations. The MCNPX code was used to simulate and track electrons generated from 30 and 50 nm diameter GNP when it is irradiated with a cobalt-60 and 6MV photon and electron beam in water. Results When a GNP was present, depending on beam types used, secondary electron production increased by 10- to 2000-fold compared to absence of a GNP. Conclusion GNPs with larger diameters also contributed to more doses. PMID:26688797

  8. Local dose enhancement in radiation therapy: Monte Carlo simulation study; Reforco local de dose em radioterapia utilizando nanoparticulas: estudo por simulacao Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Laura E. da; Nicolucci, Patricia, E-mail: laura.emilia.fm@gmail.com [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras

    2014-04-15

    The development of nanotechnology has boosted the use of nanoparticles in radiation therapy in order to achieve greater therapeutic ratio between tumor and healthy tissues. Gold has been shown to be most suitable to this task due to the high biocompatibility and high atomic number, which contributes to a better in vivo distribution and for the local energy deposition. As a result, this study proposes to study, nanoparticle in the tumor cell. At a range of 11 nm from the nanoparticle surface, results have shown an absorbed dose 141 times higher for the medium with the gold nanoparticle compared to the water for an incident energy spectrum with maximum photon energy of 50 keV. It was also noted that when only scattered radiation is interacting with the gold nanoparticles, the dose was 134 times higher compared to enhanced local dose that remained significant even for scattered radiation. (author)

  9. Dose enhancement effects to the nucleus and mitochondria from gold nanoparticles in the cytosol

    Science.gov (United States)

    McNamara, A. L.; Kam, W. W. Y.; Scales, N.; McMahon, S. J.; Bennett, J. W.; Byrne, H. L.; Schuemann, J.; Paganetti, H.; Banati, R.; Kuncic, Z.

    2016-08-01

    Gold nanoparticles (GNPs) have shown potential as dose enhancers for radiation therapy. Since damage to the genome affects the viability of a cell, it is generally assumed that GNPs have to localise within the cell nucleus. In practice, however, GNPs tend to localise in the cytoplasm yet still appear to have a dose enhancing effect on the cell. Whether this effect can be attributed to stress-induced biological mechanisms or to physical damage to extra-nuclear cellular targets is still unclear. There is however growing evidence to suggest that the cellular response to radiation can also be influenced by indirect processes induced when the nucleus is not directly targeted by radiation. The mitochondrion in particular may be an effective extra-nuclear radiation target given its many important functional roles in the cell. To more accurately predict the physical effect of radiation within different cell organelles, we measured the full chemical composition of a whole human lymphocytic JURKAT cell as well as two separate organelles; the cell nucleus and the mitochondrion. The experimental measurements found that all three biological materials had similar ionisation energies  ˜70 eV, substantially lower than that of liquid water  ˜78 eV. Monte Carlo simulations for 10-50 keV incident photons showed higher energy deposition and ionisation numbers in the cell and organelle materials compared to liquid water. Adding a 1% mass fraction of gold to each material increased the energy deposition by a factor of  ˜1.8 when averaged over all incident photon energies. Simulations of a realistic compartmentalised cell show that the presence of gold in the cytosol increases the energy deposition in the mitochondrial volume more than within the nuclear volume. We find this is due to sub-micron delocalisation of energy by photoelectrons, making the mitochondria a potentially viable indirect radiation target for GNPs that localise to the cytosol.

  10. Enhanced steroid dosing reduces seizures during antiparasitic treatment for cysticercosis and early after

    Science.gov (United States)

    Garcia, Hector H.; Gonzales, Isidro; Lescano, Andres G.; Bustos, Javier A.; Pretell, E. Javier; Saavedra, Herbert; Nash, Theodore E.

    2014-01-01

    SUMMARY Objective Neurocysticercosis is a major cause of seizures and epilepsy in endemic countries. Antiparasitic treatment of brain cysts leads to seizures due to the host’s inflammatory reaction, requiring concomitant steroids. We hypothesized that increased steroid dosing will reduce treatment-associated seizures. Methods Open-label randomized trial comparing 6 mg/d dexamethasone for 10 days (conventional) with 8 mg/d for 28 days followed by a 2 week taper (enhanced) in neurocysticercosis patients receiving albendazole. Follow up included active seizure surveillance and brain imaging. Study outcomes were seizure days and patients with seizures, both measured in days 11-42. Additional analyses compared days 1-10, 11-21, 22-32, 33-42, 43-60, and 61-180. Results Thirty-two individuals were randomized into each arm, two did not complete follow up. From days 11 to 42, 59 partial and 6 generalized seizure days occurred in 20 individuals, non-significantly fewer in the enhanced arm (12 versus 49, p=0.114). The numbers of patients with seizures in this period showed similar non-significant differences. In the enhanced steroid arm there were significantly fewer days and individuals with seizures during antiparasitic treatment (days 1-10: 4 versus 17, p=0.004, and 1 versus 10, p=0.003, number needed to treat 4.6, relative risk 0.1013, 95%CI: 0.01 – 0.74) and early after dexamethasone cessation (days 11-21: 6 versus 27, p=0.014, and 4 versus 12, p=0.021, NNT 4.0, RR 0.33, 95%CI: 0.12 – 0.92) but not after day 21. There were no significant differences in antiparasitic efficacy or relevant adverse events. Significance Increased dexamethasone dosing results in fewer seizures for the first 21 days during and early after antiparasitic treatment for viable parenchymal neurocysticercosis but not during the first 11-42 days, which was the primary predetermined time of analysis. PMID:25092547

  11. Dose enhancement in gold nanoparticle-aided radiotherapy for the therapeutic photon beams using Monte Carlo technique

    Directory of Open Access Journals (Sweden)

    Nitin Ramesh Kakade

    2015-01-01

    Full Text Available Background: Gold nanoparticle (GNP-aided radiation therapy (RT is useful to make the tumor more sensitive to radiation damage because of the enhancement in the dose inside the tumor region. Polymer gel dosimeter (PGD can be a good choice for the physical measurement of dose enhancement produced by GNP inside the gel. Materials and Methods: The present study uses EGSnrc Monte Carlo code to estimate dose enhancement factor (DEF due to the introduction of GNPs inside the PGD at different concentrations (7 and 18 mg Au/g of gel when irradiated by therapeutic X-rays of energy 100 kVp, 150 kVp, 6 MV, and 15 MV. The simulation was also carried out to quantify the dose enhancement in PAGAT gel and tumor for 100 kVp X-rays. Results: For 100 kVp X-rays, average DEF of 1.86 and 2.91 is observed in the PAGAT gel dosimeter with 7 and 18 mg Au/g of gel, respectively. Average DEF of 1.69 and 2.61 is recorded for 150 kVp X-rays with 7 and 18 mg Au/g of gel, respectively. No clinically meaningful DEF was observed for 6 and 15 MV photon beams. Furthermore, the dose enhancement within the PAGAT gel dosimeter and tumor closely matches with each other. Conclusion: The polymer gel dosimetry can be a suitable method of dose estimation and verification for clinical implementation of GNP-aided RT. GNP-aided RT has the potential of delivering high localized tumoricidal dose with significant sparing of normal structures when the treatment is delivered with low energy X-rays.

  12. Effects of orientation of substrate on the enhanced low-dose-rate sensitivity (ELDRS) in NPN transistors

    Institute of Scientific and Technical Information of China (English)

    LU Wu; ZHENG Yu-Zhan; WANG Yi-Yuan; REN Di-Yuan; GUO Qi; WANG Zhi-Kuan; WANG Jian-An

    2011-01-01

    The radiation effects and annealing characteristics of two types of domestic NPN bipolar junction transistors, fabricated with different orientations, were investigated under different dose-rate irradiation. The experimental results show that both types of the NPN transistors exhibit remarkable Enhanced Low-Dose-Rate Sensitivity (ELDRS). After irradiation at high or low dose rate, the excess base current of NPN transistors obviously increased, and the current gain would degrade rapidly. Moreover, the decrease of collector current was also observed. The NPN transistor with (111) orientation was more sensitive to ionizing radiation than that with (100) orientation. The underlying mechanisms of various experimental phenomena are discussed in detail in this paper.

  13. Effects of orientation of substrate on the enhanced low-dose-rate sensitivity (ELDRS) in NPN transistors

    Science.gov (United States)

    Lu, Wu; Zheng, Yu-Zhan; Wang, Yi-Yuan; Ren, Di-Yuan; Guo, Qi; Wang, Zhi-Kuan; Wang, Jian-An

    2011-02-01

    The radiation effects and annealing characteristics of two types of domestic NPN bipolar junction transistors, fabricated with different orientations, were investigated under different dose-rate irradiation. The experimental results show that both types of the NPN transistors exhibit remarkable Enhanced Low-Dose-Rate Sensitivity (ELDRS). After irradiation at high or low dose rate, the excess base current of NPN transistors obviously increased, and the current gain would degrade rapidly. Moreover, the decrease of collector current was also observed. The NPN transistor with orientation was more sensitive to ionizing radiation than that with orientation. The underlying mechanisms of various experimental phenomena are discussed in detail in this paper.

  14. Boron fertilization on sweet potato: effect of sources, rates and application formAdubação com boro em batata-doce: efeito das fontes, doses e modos de aplicação

    Directory of Open Access Journals (Sweden)

    José Eduardo Creste

    2011-12-01

    Full Text Available Boron (B fertilization can result in high yield and better sweet potato storage roots quality. However, there is few works about this subject. The objective was to evaluate the yield of sweet potato crops in response to B sources, rates and application form. The experimental design was complete randomized blocks, in factorial outline ((2x2x2+1, with three replications, which resulted of the combination of sources of B (boric acid and borax, application form (via soil and via foliar and doses of B (1 and 2 kg ha-1 and a control treatment (without B. There was no interaction between the factors studied for the commercial yield of sweet potato. No significant differences was found between B sources and application form, but they showed higher yield than the control treatment. Additionally, sweet potato yield increade with application of 2 kg ha-1 of B.A adubação boratada pode proporcionar aumentos na produtividade e na qualidade das raízes tuberosas de batata-doce, no entanto poucos trabalhos contemplam esse assunto. Objetivou-se avaliar a produtividade da cultura da batata-doce em resposta a fontes, doses e modos de aplicação de B. O delineamento experimental utilizado foi o de blocos casualizados, em esquema fatorial ((2x2x2+1, com três repetições. Os tratamentos foram aplicados em cobertura, sendo resultados da combinação de fontes de B (ácido bórico e bórax, formas de aplicação (via solo e via foliar e doses de B (1 e 2 kg ha-1 mais uma testemunha. Não houve interação entre os fatores estudados sobre a produtividade comercial de batata-doce. As formas de aplicação, via solo e via foliar bem como as fontes ácido bórico e bórax não apresentaram diferenças entre si, mas proporcionaram produtividades superiores ao tratamento sem B. A produtividade de batata-doce foi favorecida com a aplicação de 2 kg ha-1 de B.

  15. Delayed enhancement imaging of myocardial viability: low-dose high-pitch CT versus MRI

    Energy Technology Data Exchange (ETDEWEB)

    Goetti, Robert; Feuchtner, Gudrun; Stolzmann, Paul; Donati, Olivio F.; Frauenfelder, Thomas; Leschka, Sebastian; Alkadhi, Hatem [University Hospital Zurich, Department of Radiology, Zurich (Switzerland); Wieser, Monika; Plass, Andre [University Hospital Zurich, Division of Cardiac and Vascular Surgery, Zurich (Switzerland)

    2011-10-15

    To evaluate the accuracy of high-pitch delayed enhancement (DE) CT for the assessment of myocardial viability with MRI as the reference standard. Twenty-four patients (mean age 66.9 {+-} 9.2 years) with coronary artery disease underwent DE imaging with 128-slice dual-source CT (prospective electrocardiography (ECG)-triggering) and MRI at 1.5 T. Two observers assessed DE transmurality per segment, and measured signal intensity (MRI) or attenuation (CT) in infarcted and healthy myocardium and noise in the left ventricular blood pool for calculating contrast-to-noise ratios (CNR). 75/408 (18.4%) segments in 18/24 patients (75.0%) showed DE in MRI, of which 28 segments in 10/24 (41.7%) patients were non-viable (scar tissue transmurality >50%). Sensitivity, specificity and accuracy of CT for diagnosis of non-viability were 60.7%, 96.8% and 94.4% per segment, and 90.0%, 92.9% and 91.7% per patient. CNR was significantly higher in MR (7.4 {+-} 3.0 vs. 4.6 {+-} 1.5; p = 0.018), and image noise significantly lower (11.6 {+-} 5.7 vs.15.0 {+-} 4.5; p = 0.019). Radiation dose of DECT was 0.89 {+-} 0.07 mSv. CTDE imaging in the high-pitch mode enables myocardial viability assessment at a low radiation dose and good accuracy compared with MR, although associated with a lower CNR and higher noise. (orig.)

  16. Boron in sillimanite.

    Science.gov (United States)

    Grew, E S; Hinthorne, J R

    1983-08-05

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

  17. Clinical comparison of dose calculation using the enhanced collapsed cone algorithm vs. a new Monte Carlo algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Fotina, Irina; Kragl, Gabriele; Kroupa, Bernhard; Trausmuth, Robert; Georg, Dietmar [Medical Univ. Vienna (Austria). Division of Medical Radiation Physics, Dept. of Radiotherapy

    2011-07-15

    Comparison of the dosimetric accuracy of the enhanced collapsed cone (eCC) algorithm with the commercially available Monte Carlo (MC) dose calculation for complex treatment techniques. A total of 8 intensity-modulated radiotherapy (IMRT) and 2 stereotactic body radiotherapy (SBRT) lung cases were calculated with eCC and MC algorithms with the treatment planning systems (TPS) Oncentra MasterPlan 3.2 (Nucletron) and Monaco 2.01 (Elekta/CMS). Fluence optimization as well as sequencing of IMRT plans was primarily performed using Monaco. Dose prediction errors were calculated using MC as reference. The dose-volume histrogram (DVH) analysis was complemented with 2D and 3D gamma evaluation. Both algorithms were compared to measurements using the Delta4 system (Scandidos). Recalculated with eCC IMRT plans resulted in lower planned target volume (PTV) coverage, as well as in lower organs-at-risk (OAR) doses up to 8%. Small deviations between MC and eCC in PTV dose (1-2%) were detected for IMRT cases, while larger deviations were observed for SBRT (up to 5%). Conformity indices of both calculations were similar; however, the homogeneity of the eCC calculated plans was slightly better. Delta4 measurements confirmed high dosimetric accuracy of both TPS. Mean dose prediction errors < 3% for PTV suggest that both algorithms enable highly accurate dose calculations under clinical conditions. However, users should be aware of slightly underestimated OAR doses using the eCC algorithm. (orig.)

  18. Estimation of tumour dose enhancement due to gold nanoparticles during typical radiation treatments: a preliminary Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S H [Department of Radiation Physics, University of Texas M D Anderson Cancer Center, 1515 Holcombe Blvd, Unit 94, Houston, TX 77030 (United States)

    2005-08-07

    A recent mice study demonstrated that gold nanoparticles could be safely administered and used to enhance the tumour dose during radiation therapy. The use of gold nanoparticles seems more promising than earlier methods because of the high atomic number of gold and because nanoparticles can more easily penetrate the tumour vasculature. However, to date, possible dose enhancement due to the use of gold nanoparticles has not been well quantified, especially for common radiation treatment situations. Therefore, the current preliminary study estimated this dose enhancement by Monte Carlo calculations for several phantom test cases representing radiation treatments with the following modalities: 140 kVp x-rays, 4 and 6 MV photon beams, and {sup 192}Ir gamma rays. The current study considered three levels of gold concentration within the tumour, two of which are based on the aforementioned mice study, and assumed either no gold or a single gold concentration level outside the tumour. The dose enhancement over the tumour volume considered for the 140 kVp x-ray case can be at least a factor of 2 at an achievable gold concentration of 7 mg Au/g tumour assuming no gold outside the tumour. The tumour dose enhancement for the cases involving the 4 and 6 MV photon beams based on the same assumption ranged from about 1% to 7%, depending on the amount of gold within the tumour and photon beam qualities. For the {sup 192}Ir cases, the dose enhancement within the tumour region ranged from 5% to 31%, depending on radial distance and gold concentration level within the tumour. For the 7 mg Au/g tumour cases, the loading of gold into surrounding normal tissue at 2 mg Au/g resulted in an increase in the normal tissue dose, up to 30%, negligible, and about 2% for the 140 kVp x-rays, 6 MV photon beam, and {sup 192}Ir gamma rays, respectively, while the magnitude of dose enhancement within the tumour was essentially unchanged. (note)

  19. Estimation of tumour dose enhancement due to gold nanoparticles during typical radiation treatments: a preliminary Monte Carlo study.

    Science.gov (United States)

    Cho, Sang Hyun

    2005-08-07

    A recent mice study demonstrated that gold nanoparticles could be safely administered and used to enhance the tumour dose during radiation therapy. The use of gold nanoparticles seems more promising than earlier methods because of the high atomic number of gold and because nanoparticles can more easily penetrate the tumour vasculature. However, to date, possible dose enhancement due to the use of gold nanoparticles has not been well quantified, especially for common radiation treatment situations. Therefore, the current preliminary study estimated this dose enhancement by Monte Carlo calculations for several phantom test cases representing radiation treatments with the following modalities: 140 kVp x-rays, 4 and 6 MV photon beams, and 192Ir gamma rays. The current study considered three levels of gold concentration within the tumour, two of which are based on the aforementioned mice study, and assumed either no gold or a single gold concentration level outside the tumour. The dose enhancement over the tumour volume considered for the 140 kVp x-ray case can be at least a factor of 2 at an achievable gold concentration of 7 mg Au/g tumour assuming no gold outside the tumour. The tumour dose enhancement for the cases involving the 4 and 6 MV photon beams based on the same assumption ranged from about 1% to 7%, depending on the amount of gold within the tumour and photon beam qualities. For the 192Ir cases, the dose enhancement within the tumour region ranged from 5% to 31%, depending on radial distance and gold concentration level within the tumour. For the 7 mg Au/g tumour cases, the loading of gold into surrounding normal tissue at 2 mg Au/g resulted in an increase in the normal tissue dose, up to 30%, negligible, and about 2% for the 140 kVp x-rays, 6 MV photon beam, and 192Ir gamma rays, respectively, while the magnitude of dose enhancement within the tumour was essentially unchanged.

  20. Preliminary study of MAGAT polymer gel dosimetry for boron-neutron capture therapy

    Science.gov (United States)

    Hayashi, Shin-ichiro; Sakurai, Yoshinori; Uchida, Ryohei; Suzuki, Minoru; Usui, Shuji; Tominaga, Takahiro

    2015-01-01

    MAGAT gel dosimeter with boron is irradiated in Heavy Water Neutron Irradiation Facility (HWNIF) of Kyoto University Research Reactor (KUR). The cylindrical gel phantoms are exposed to neutron beams of three different energy spectra (thermal neutron rich, epithermal and fast neutron rich and the mixed modes) in air. Preliminary results corresponding to depth-dose responses are obtained as the transverse relaxation rate (R2=1/T2) from magnetic resonance imaging data. As the results MAGAT gel dosimeter has the higher sensitivity on thermal neutron than on epi-thermal and fast neutron, and the gel with boron showed an enhancement and a change in the depth-R2 response explicitly. From these results, it is suggested that MAGAT gel dosimeter can be an effective tool in BNCT dosimetry.

  1. Effect of Photon Beam Energy, Gold Nanoparticle Size and Concentration on the Dose Enhancement in Radiation Therapy

    Directory of Open Access Journals (Sweden)

    Nahideh Gharehaghaji

    2013-02-01

    Full Text Available Introduction: Gold nanoparticles have been used as radiation dose enhancing materials in recent investigations. In the current study, dose enhancement effect of gold nanoparticles on tumor cells was evaluated using Monte Carlo (MC simulation. Methods: We used MCNPX code for MC modeling in the current study. A water phantom and a tumor region with a size of 1×1×1 cm3 loaded with gold nanoparticles were simulated. The macroscopic dose enhancement factor was calculated for gold nanoparticles with sizes of 30, 50, and 100 nm. Also, we simulated different photon beams including mono-energetic beams (50-120 keV, a Cobalt-60 beam, 6 & 18 MV photon beams of a conventional linear accelerator. Results: We found a dose enhancement factor (DEF of from 1.4 to 3.7 for monoenergetic kilovoltage beams, while the DEFs for megavoltage beams were negligible and less than 3% for all GNP sizes and concentrations. The optimum energy for higher DEF was found to be the 90 keV monoenergetic beam. The effect of GNP size was not considerable, but the GNP concentration had a substantial impact on achieved DEF in GNP-based radiation therapy. Conclusion: The results were in close agreement with some previous studies considering the effect of photon energy and GNP concentration on observed DEF. Application of GNP-based radiation therapy using kilovoltage beams is recommended.

  2. Depth resolved investigations of boron implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Sztucki, M. E-mail: michael@sztucki.de; Metzger, T.H.; Milita, S.; Berberich, F.; Schell, N.; Rouviere, J.L.; Patel, J

    2003-01-01

    We have studied the depth distribution and structure of defects in boron implanted silicon (0 0 1). Silicon wafers were implanted with a boron dose of 6x10{sup 15} ions/cm{sup -2} at 32 keV and went through different annealing treatments. Using diffuse X-ray scattering at grazing incidence and exit angles we are able to distinguish between different kinds of defects (point defect clusters and extrinsic stacking faults on {l_brace}1 1 1{r_brace} planes) and to determine their depth distribution as a function of the thermal budget. Cross-section transmission electron microscopy was used to gain complementary information. In addition we have determined the strain distribution caused by the boron implantation as a function of depth from rocking curve measurements.

  3. Investigation of bias dependence on enhanced low dose rate sensitivity in SiGe HBTs for space application

    Science.gov (United States)

    Sun, Yabin; Fu, Jun; Xu, Jun; Wang, Yudong; Zhou, Wei; Zhang, Wei; Cui, Jie; Li, Gaoqing; Liu, Zhihong

    2014-02-01

    NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were exposed to 60Co gamma source at different dose rates under two bias conditions. Excess base currents and normalized current gains are used to quantify performance degradation. Experiment results demonstrate that the lower the dose rate, the more the irradiation damage, and some enhanced low dose rate sensitivity (ELDRS) exists in SiGe HBTs. The ELDRS effect is found to depend highly on the bias condition during exposure, and the transistors with forward active mode exhibit a more serious ELDRS effect compared to the floating case. The performance degradation at different dose rates and bias conditions is compared and discussed, and furthermore the underlying physical mechanisms are analyzed and investigated in detail.

  4. Enhancement in dose sensitivity of polymer gel dosimeters composed of radiation-crosslinked gel matrix and less toxic monomers

    Science.gov (United States)

    Hiroki, A.; Yamashita, S.; Taguchi, M.

    2015-01-01

    Polymer gel dosimeters based on radiation-crosslinked hydroxypropyl cellulose gel were prepared, which comprised 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol #400 dimethacrylate (9G) as less toxic monomers and tetrakis (hydroxymethyl) phosphonium chloride (THPC) as an antioxidant. The dosimeters exposed to 60Co γ-rays became cloudy at only 1 Gy. The irradiated dosimeters were optically analyzed by using a UV- vis spectrophotometer to evaluate dose response. Absorbance of the dosimeters linearly increased in the dose range from 0 to 10 Gy, in which dose sensitivity increased with increasing 9G concentration. The dose sensitivity of the dosimeters with 2 wt% HEMA and 3 wt% 9G was also enhanced by increment in THPC.

  5. Boron-Loaded Silicone Rubber Scintillators

    CERN Document Server

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

    2003-01-01

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

  6. Dose response and time course of manganese-enhanced magnetic resonance imaging for visual pathway tracing in vivo

    Institute of Scientific and Technical Information of China (English)

    Wei-ling Wang; Hui Xu; Ying Li; Zhi-zhong Ma; Xiao-dong Sun; Yun-tao Hu

    2016-01-01

    Axonal tracing is useful for detecting optic nerve injury and regeneration, but many commonly used methods cannot be used to observe axoplasmic lfow and synaptic transmission in vivo. Manganese (Mn2+)-enhanced magnetic resonance imaging (MEMRI) can be used for in vivo longitudinal tracing of the visual pathway. Here, we explored the dose response and time course of an intravitreal injection of MnCl2 for tracing the visual pathway in rabbits in vivo using MEMRI. We found that 2 mM MnCl2 enhanced images of the optic nerve but not the lateral geniculate body or superior colliculus, whereas at all other doses tested (5–40 mM), images of the visual pathway from the retina to the contralateral superior colliculus were signiifcantly enhanced. The images were brightest at 24 hours, and then decreased in brightness until the end of the experiment (7 days). No signal enhancement was observed in the visual cortex at any concentration of MnCl2. These results suggest that MEMRI is a viable method for temporospatial tracing of the visual pathway in vivo. Signal enhancement in MEMRI de-pends on the dose of MnCl2, and the strongest signals appear 24 hours after intravitreal injection.

  7. SU-E-T-279: Dose Enhancement Effect Due to Cerium Oxide Nanoparticles Employed as Radiation Protectants

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Z; Altundal, Y; Sajo, E [Univ Massachusetts Lowell, Lowell, MA (United States); Ngwa, W [Univ Massachusetts Lowell, Lowell, MA (United States); Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical, Boston, MA (United States)

    2015-06-15

    Purpose: The goal of radiotherapy is to maximize radiation dose to diseased cells while minimizing radiation damage to normal tissues. In order to minimize damage to normal tissues, cerium oxide nanoparticles (nanoceria) are currently considered as a radioprotectant. However, some studies have reported concerns that nanoceria can also lead to radiotherapy dose enhancement due to the high atomic number of cerium, especially when used in conjunction with kV energy and brachytherapy sources. In this study, this concern is investigated to determine if the concentrations of nanoceria employed in in-vivo studies to confer radioprotection can engender a significant dose enhancement. Methods: Radiation with energies ranging from 50kVp to 140kVp is investigated in this work along with brachytherapy sources Pd-103 and I-125. A previously established theoretical model is used to calculate the dose enhancement factor (DEF). In this model, each cell is assumed to be a voxel of size (10 µm, 10 µm, 10 µm) with nanoceria homogeneously distributed among them. Electron energy loss formula of Cole is used to calculate energy (and hence dose) deposited by photoelectrons and Auger electrons in each tissue voxel due to irradiation of nanoceria. The DEF is defined as the ratio of the dose with and without nanoparticles. Results: DEF calculation results are smaller than 1.02 with dosages of nanoceria smaller than 0.645 mg/g, which is shown to be sufficiently protective by some previous in-vitro and in-vivo experiments. The brachytherapy sources show higher DEF’s than kVp radiations. DEF peaks are consistent with K shell and L shell energies of cerium, 40 keV and 6 keV, respectively. Conclusion: The results show that for sufficiently radioprotective concentrations of nanoceria, there will be minimal DEF when used in conjunction with clinically applicable kV energy radiotherapy sources or brachytherapy sources.

  8. Thin-film CdTe detector for microdosimetric study of radiation dose enhancement at gold-tissue interface.

    Science.gov (United States)

    Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

    2016-09-08

    Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three-micron thick thin-film CdTe photodetectors were fabricated in our lab. One-, ten- or one hundred-micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high-dose-rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5μm from the interface were 42.6 ± 10.8 , 137.0 ± 11.9, and 203.0 ± 15.4, respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1, and 249 ± 1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold-tissue interface was successfully measured using an in-house-built, high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.

  9. Boron analysis for neutron capture therapy using particle-induced gamma-ray emission.

    Science.gov (United States)

    Nakai, Kei; Yamamoto, Yohei; Okamoto, Emiko; Yamamoto, Tetsuya; Yoshida, Fumiyo; Matsumura, Akira; Yamada, Naoto; Kitamura, Akane; Koka, Masashi; Satoh, Takahiro

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18 μgB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20 min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm.

  10. Boron and the kidney.

    Science.gov (United States)

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

    2005-10-01

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

  11. Juvenile Hormone Analogues, Methoprene and Fenoxycarb Dose-Dependently Enhance Certain Enzyme Activities in the Silkworm Bombyx Mori (L

    Directory of Open Access Journals (Sweden)

    M. Rajeswara Rao

    2008-06-01

    Full Text Available Use of Juvenile Hormone Analogues (JHA in sericulture practices has been shown to boost good cocoon yield; their effect has been determined to be dose-dependent. We studied the impact of low doses of JHA compounds such as methoprene and fenoxycarb on selected key enzymatic activities of the silkworm Bombyx mori. Methoprene and fenoxycarb at doses of 1.0 μg and 3.0fg/larvae/48 hours showed enhancement of the 5th instar B. mori larval muscle and silkgland protease, aspartate aminotransaminase (AAT and alanine aminotransaminase (ALAT, adenosine triphosphate synthase (ATPase and cytochrome-c-oxidase (CCO activity levels, indicating an upsurge in the overall oxidative metabolism of the B.mori larval tissues.

  12. Enhanced therapeutic tumour dose of /sup 131/I-MIBG by accelerated diuresis

    Energy Technology Data Exchange (ETDEWEB)

    Darte, L.; Tennvall, J.

    1988-10-01

    Different biokinetics of intravenously (i.v.) administered /sup 131/I-MIBG in the same patient, a child with abdominal neuroblastoma, is demonstrated with and without accelerated elimination by means of hyperhydration. By hyperhydration it was possible to increase the estimated tumour dose by a factor of 2.1 without affecting the whole body dose. The present results indicate that, if accelerated diuresis is implemented, higher radioactivity of /sup 131/I-MIBG can be administered and thereby an increased therapeutic tumour dose achieved.

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

    Science.gov (United States)

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

    2016-03-01

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

  14. Effect of Uniform and Non-uniform High-z Nanoparticles Distribution in Tumor Volume on Dose Enhancement Factor During 192Ir Brachytherapy

    Directory of Open Access Journals (Sweden)

    M Zabihzadeh

    2013-12-01

    Conclusion: increase of atomic number and concentrations of NPs enhance the absorbed dose due to increased possibility of photoelectric phenomena. Non-uniform distribution of NPs underestimated dose compared to uniform distribution; therefore, considering accurate NPs distribution inside the tumor volume is crucial to calculation of dose enhancement. Targeted labeling of NPs for the maximum absorption by tumor and for the minimal penetration into peripheral tissues has potential to increase radiation therapeutic ratio.

  15. Probing Field Emission from Boron Carbide Nanowires

    Institute of Scientific and Technical Information of China (English)

    TIAN Ji-Fa; GAO Hong-Jun; BAO Li-Hong; WANG Xing-Jun; HUI Chao; LIU Fei; LI Chen; SHEN Cheng-Min; WANG Zong-Li; GU Chang-Zhi

    2008-01-01

    High density boron carbide nanowires are grown by an improved carbon thermal reduction technique. Transmission electron microscopy and electron energy lose spectroscopy of the sample show that the synthesized nanowires are B4 C with good crystallization. The field emission measurement for an individual boron nanowire is performed by using a Pt tip installed in the focused ion beam system. A field emission current with enhancement factor of 106 is observed and the evolution process during emission is also carefully studied. Furthermore, a two-step field emission with stable emission current density is found from the high-density nanowire film. Our results together suggest that boron carbide nanowires are promising candidates for electron emission nanodevices.

  16. Update on human health effects of boron.

    Science.gov (United States)

    Nielsen, Forrest H

    2014-10-01

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

  17. Enhancement of hydralazine hypotension by low doses of isoniazid. Possible role of semicarbazide-sensitive amine oxidase inhibition.

    Science.gov (United States)

    Vidrio, H; Medina, M; Fernandez, G; Lorenzana-Jimenez, M; Campos, A E

    2000-10-01

    The influence of pretreatment with 1 through 300 mg/kg ip of isoniazid (ISO) on blood pressure and heart rate responses to 0.1 mg/kg iv of hydralazine (HYD) was assessed in rats anesthetized with chloralose--urethane. HYD hypotension was significantly enhanced by ISO at doses between 3 and 300 mg/kg ip. Heart rate was not influenced by HYD in control or pretreated animals. Depressor responses to 0.2 mg/kg iv of pinacidil (PIN) were also potentiated by ISO at 100 and 300, but not at 30 mg/kg. Similarly, ISO decreased cerebral gamma-aminobutyric acid (GABA) at the two highest doses; 30 mg/kg was without effect. Pretreatment of rats with ISO at 1 through 300 mg/kg failed to influence HYD-induced relaxation of aortic rings. These results were interpreted as indicating that potentiation of HYD hypotension by high doses of ISO is not specific for that vasodilator and is related to decreased cerebral GABA, as postulated previously. Lower doses could specifically potentiate the HYD-induced hypotensive effect by inhibition of semicarbazide-sensitive amine oxidase (SSAO), since both ISO and HYD are potent inhibitors of this enzyme. In support of this hypothesis, the SSAO inhibitors, benserazide (100 mg/kg ip) and mexiletine (50 mg/kg ip), were also found to enhance HYD hypotension.

  18. Molecularly Targeted Dose-Enhancement Radiotherapy Using Gold and Luminescent Nanoparticles in an Orthotopic Human Prostate Cancer Rat Model

    Science.gov (United States)

    2013-10-01

    claim that because different cell types should have different mechanism of endocytosis and delivering mechanisms. On DU-145, PC-3, and LNCap prostate...deaths. These parameters could be the size of nanoparticles, shape of nanoparticles, different mechanism of cell endocytosis , sensitivity of cells to...and equilibrating endocytosis . Whenever dose enhanced radiation therapy based on photoelectric effect is discussed, Auger electrons are the primary

  19. Boron-Based Drug Design.

    Science.gov (United States)

    Ban, Hyun Seung; Nakamura, Hiroyuki

    2015-06-01

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

  20. Boron nitride composites

    Science.gov (United States)

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

    2016-02-16

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

  1. 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.

  2. Application of proton boron fusion reaction to radiation therapy: A Monte Carlo simulation study

    Science.gov (United States)

    Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk

    2014-12-01

    Three alpha particles are emitted from the point of reaction between a proton and boron. The alpha particles are effective in inducing the death of a tumor cell. After boron is accumulated in the tumor region, the emitted from outside the body proton can react with the boron in the tumor region. An increase of the proton's maximum dose level is caused by the boron and only the tumor cell is damaged more critically. In addition, a prompt gamma ray is emitted from the proton boron reaction point. Here, we show that the effectiveness of the proton boron fusion therapy was verified using Monte Carlo simulations. We found that a dramatic increase by more than half of the proton's maximum dose level was induced by the boron in the tumor region. This increase occurred only when the proton's maximum dose point was located within the boron uptake region. In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. This therapy method features the advantages such as the application of Bragg-peak to the therapy, the accurate targeting of tumor, improved therapy effects, and the monitoring of the therapy region during treatment.

  3. Boron Removal in Seawater Reverse Osmosis System

    KAUST Repository

    Rahmawati, Karina

    2011-07-01

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

  4. Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Berbeco, Ross I., E-mail: rberbeco@partners.org; Detappe, Alexandre [Department of Radiation Oncology, Brigham and Women’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States); Tsiamas, Panogiotis [Department of Radiation Oncology, St. Jude Children’s Hospital, Memphis, Tennessee 38105 (United States); Parsons, David; Yewondwossen, Mammo; Robar, James [Department of Radiation Oncology and Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 1V7 (Canada)

    2016-01-15

    Purpose: Previous studies have introduced gold nanoparticles as vascular-disrupting agents during radiation therapy. Crucial to this concept is the low energy photon content of the therapy radiation beam. The authors introduce a new mode of delivery including a linear accelerator target that can toggle between low Z and high Z targets during beam delivery. In this study, the authors examine the potential increase in tumor blood vessel endothelial cell radiation dose enhancement with the low Z target. Methods: The authors use Monte Carlo methods to simulate delivery of three different clinical photon beams: (1) a 6 MV standard (Cu/W) beam, (2) a 6 MV flattening filter free (Cu/W), and (3) a 6 MV (carbon) beam. The photon energy spectra for each scenario are generated for depths in tissue-equivalent material: 2, 10, and 20 cm. The endothelial dose enhancement for each target and depth is calculated using a previously published analytic method. Results: It is found that the carbon target increases the proportion of low energy (<150 keV) photons at 10 cm depth to 28% from 8% for the 6 MV standard (Cu/W) beam. This nearly quadrupling of the low energy photon content incident on a gold nanoparticle results in 7.7 times the endothelial dose enhancement as a 6 MV standard (Cu/W) beam at this depth. Increased surface dose from the low Z target can be mitigated by well-spaced beam arrangements. Conclusions: By using the fast-switching target, one can modulate the photon beam during delivery, producing a customized photon energy spectrum for each specific situation.

  5. Low-Dose Dextromethorphan, a NADPH Oxidase Inhibitor, Reduces Blood Pressure and Enhances Vascular Protection in Experimental Hypertension

    Science.gov (United States)

    Wu, Tao-Cheng; Chao, Chih-Yu; Lin, Shing-Jong; Chen, Jaw-Wen

    2012-01-01

    Background Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM), a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP) and vascular protection in aged spontaneous hypertensive rats (SHRs). Methodology/Principal Findings Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker) monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells. Conclusions/Significance Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension. PMID:23049937

  6. Low-dose dextromethorphan, a NADPH oxidase inhibitor, reduces blood pressure and enhances vascular protection in experimental hypertension.

    Directory of Open Access Journals (Sweden)

    Tao-Cheng Wu

    Full Text Available BACKGROUND: Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM, a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP and vascular protection in aged spontaneous hypertensive rats (SHRs. METHODOLOGY/PRINCIPAL FINDINGS: Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells. CONCLUSIONS/SIGNIFICANCE: Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension.

  7. Double dose: High family conflict enhances the effect of media violence exposure on adolescents’ aggression

    NARCIS (Netherlands)

    Fikkers, K.M.; Piotrowski, J.T.; Weeda, W.D.; Vossen, H.G.M.; Valkenburg, P.M.

    2013-01-01

    We investigated how exposure to media violence and family conflict affects adolescents’ subsequent aggressive behavior. We expected a double dose effect, meaning that high media violence exposure would lead to higher levels of aggression for adolescents in high conflict families compared to low conf

  8. Defects involving interstitial boron in low-temperature irradiated silicon

    Science.gov (United States)

    Khirunenko, L. I.; Sosnin, M. G.; Duvanskii, A. V.; Abrosimov, N. V.; Riemann, H.

    2016-12-01

    Interstitial boron-related defects in silicon subjected to irradiation with 5 MeV electrons at a temperature of 80 K are investigated by Fourier-transform infrared absorption spectroscopy. This study demonstrates the radiation-enhanced annealing of interstitial boron during irradiation. We have revealed the interaction, which occurs in the course of irradiation, of diffusing interstitial boron atoms with one another and with interstitial oxygen. The local vibrational modes associated with these defects are identified, and the thermal stability of the defects is determined.

  9. 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.

  10. Boronated liposome development and evaluation

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-11-01

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

  11. Double Dose: High Family Conflict Enhances the Effect of Media Violence Exposure on Adolescents’ Aggression

    Directory of Open Access Journals (Sweden)

    Patti M. Valkenburg

    2013-07-01

    Full Text Available We investigated how exposure to media violence and family conflict affects adolescents’ subsequent aggressive behavior. We expected a double dose effect, meaning that high media violence exposure would lead to higher levels of aggression for adolescents in high conflict families compared to low conflict families. A total of 499 adolescents (aged 10 to 14, 48% girls participated in a two-wave longitudinal survey (4-month interval. Survey questions assessed their exposure to violence on television and in electronic games, family conflict, and aggressive behavior. Analyses revealed a significant interaction between media violence and family conflict. In families with higher conflict, higher media violence exposure was related to increased subsequent aggression. This study is the first to show a double dose effect of media violence and family conflict on adolescents’ aggression. These findings underscore the important role of the family in shaping the effects of adolescents’ media use on their social development.

  12. Double Dose: High Family Conflict Enhances the Effect of Media Violence Exposure on Adolescents’ Aggression

    OpenAIRE

    Valkenburg, Patti M.; Vossen, Helen G.M.; Weeda, Wouter D.; Jessica Taylor Piotrowski; Karin M. Fikkers

    2013-01-01

    We investigated how exposure to media violence and family conflict affects adolescents’ subsequent aggressive behavior. We expected a double dose effect, meaning that high media violence exposure would lead to higher levels of aggression for adolescents in high conflict families compared to low conflict families. A total of 499 adolescents (aged 10 to 14, 48% girls) participated in a two-wave longitudinal survey (4-month interval). Survey questions assessed their exposure to violence on telev...

  13. Low doses of imatinib induce myelopoiesis and enhance host anti-microbial immunity.

    Directory of Open Access Journals (Sweden)

    Ruth J Napier

    2015-03-01

    Full Text Available Imatinib mesylate (Gleevec inhibits Abl1, c-Kit, and related protein tyrosine kinases (PTKs and serves as a therapeutic for chronic myelogenous leukemia and gastrointestinal stromal tumors. Imatinib also has efficacy against various pathogens, including pathogenic mycobacteria, where it decreases bacterial load in mice, albeit at doses below those used for treating cancer. We report that imatinib at such low doses unexpectedly induces differentiation of hematopoietic stem cells and progenitors in the bone marrow, augments myelopoiesis but not lymphopoiesis, and increases numbers of myeloid cells in blood and spleen. Whereas progenitor differentiation relies on partial inhibition of c-Kit by imatinib, lineage commitment depends upon inhibition of other PTKs. Thus, imatinib mimics "emergency hematopoiesis," a physiological innate immune response to infection. Increasing neutrophil numbers by adoptive transfer sufficed to reduce mycobacterial load, and imatinib reduced bacterial load of Franciscella spp., which do not utilize imatinib-sensitive PTKs for pathogenesis. Thus, potentiation of the immune response by imatinib at low doses may facilitate clearance of diverse microbial pathogens.

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-06-06

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

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

    Science.gov (United States)

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

    2015-12-01

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

  17. Removing Boron from an Aqueous Solution Using Turmeric Extract-Aided Coagulation-Flocculation

    Directory of Open Access Journals (Sweden)

    Azhar Abdul Halim

    2012-01-01

    Full Text Available Problem statement: Boron exists in an environment naturally either through weathering of rocks or volcanic activity but due to anthropogenic activity, boron had been distributed widely into our surroundings. Boron was a problematic pollutant due to the difficulty to remove it from the water. Turmeric which had been widely used as a spice and traditional medicine, were investigated to determine its capabilities to aid in coagulation-flocculation process to remove boron. Optimizing coagulation-flocculation process might be effective to remove boron to a lower concentration. Approach: In this study, the optimum parameter for pH, dose of aluminium sulfate (alum and a dose of turmeric extract were determined by conducting a set of jar test experiment. The coagulation-flocculation process was performed to study the effectiveness of the turmeric extract as a coagulant aid in boron removal. Results: The result demonstrated that coagulation-flocculation process with the aid of turmeric extract can remove boron effectively at optimum conditions rather than coagulation-flocculation process without the aid of turmeric extract. The optimum conditions for boron removal were achieved at pH 7, an alum dosage of 18, 367 mg L-1 and turmeric extract dosage of 82 mg L-1. Conclusion/Recommendations: Result showed that removal of boron depends on pH, alum dosage and turmeric extract dosage. The boron removal percentage of the aqueous solution using the coagulation-flocculation process aided by the addition of turmeric extract and without the addition of turmeric extract were 95 and 62%, respectively. In addition, there was a significance difference between both processes. Turmeric extract as a coagulant aid demonstrated promising performance in boron removal and can be used as an alternative treatment to treat boron-containing wastewater.

  18. Studying Effects of Gold Nanoparticle on Dose Enhancement in Megavoltage Radiation

    Directory of Open Access Journals (Sweden)

    Khadem Abolfazli M.

    2015-12-01

    Full Text Available Background: Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers. Objective: The aim of this study is to understand characteristics of secondary electrons generated from interaction of gold nanoparticles GNPs with x-rays as a function of nanoparticle size and beam energy and thereby further understanding of GNPenhanced radiotherapy. Methods: Effective range, defection angle, dose deposition, energy, and interaction processes of electrons produced from the interaction of x-rays with a GNP were calculated by Monte Carlo simulations. The MCNPX code was used to simulate and track electrons generated from 30 and 50 nm diameter GNP when it is irradiated with a cobalt-60 and 6MV photon and electron beam in water. Results: When a GNP was present, depending on beam types used, secondary electron production increased by 10- to 2000-fold compared to absence of a GNP. Conclusion: GNPs with larger diameters also contributed to more doses.

  19. Response of Boron and Light on Morph-Physiology and Pod Yield of Two Peanut Varieties

    OpenAIRE

    Md. Quamruzzaman; Md. Jafar Ullah; Md. Fazlul Karim; Nazrul Islam; Md. Jahedur Rahman; Md. Dulal Sarkar

    2016-01-01

    Boron is an important micronutrient that enhances vegetative growth and yield of crops, like peanut. Light also plays an important role in pegging of peanut. There has been little information regarding the application of boron and light in peanut in Bangladesh. Therefore, a field experiment was conducted to study the response of boron and light on morph-physiology and pod yield of two peanut varieties. Treatments considered two peanut varieties, namely, Dhaka-1 and BARI Chinabadam-8, three le...

  20. Crescimento e teores de clorofila em mudas de bananeira em função da supressão do pseudocaule, de doses de nitrogênio e de boro Growth and chlorophyll content of banana suckers in function of pseudostem suppression and doses of nitrogen and boron

    Directory of Open Access Journals (Sweden)

    Walter Esfrain Pereira

    2010-12-01

    Full Text Available O objetivo deste experimento foi avaliar a influência da eliminação da gema apical do rizoma e de doses de nitrogênio e boro, sobre a produção e o crescimento de mudas de bananeira. O experimento foi realizado no Centro de Formação de Tecnólogos da UFPB. O delineamento foi em blocos casualizados, com quatro blocos e nove plantas matrizes por parcela, sendo duas plantas úteis. Os fatores avaliados foram doses de N (0 a 240 g/planta e de B (0 a 2,2 g/planta combinados com a matriz experimental Composto Central de Box, originando nove combinações, arranjados fatorialmente com e sem eliminação da gema apical da planta matriz. Os dados foram submetidos à análise de variância e de regressão. A supressão do pseudocaule da planta principal, com a eliminação da gema apical do rizoma aumentou o número de perfilhos, com maior crescimento, exceto do diâmetro do rizoma, o qual diminuiu. Os teores foliares de clorofila total e de B também foram diminuídos, nos perfilhos das bananeiras amputadas. Para a produção de mudas da bananeira ‘Pacovan’, recomenda-se a supressão do pseudocaule da planta principal, com eliminação da gema apical do rizoma e aplicação do N.The objective of this research was to evaluate the influence of the removal in the pseudostem with elimination of the meristem apical of the rhizome and doses of nitrogen and boron, about the production and growth of banana suckers. The experiment was carried out at Centro de Formação de Tecnólogos - UFPB, State of Paraíba. The experimental design was in randomized blocks, with four replications and nine mother plants for experimental unit, being two useful plants. The evaluated valued factors were doses of N (0 to 240 g plant-1 and of B (0 to 240 g plant-1 combined in agreement with the experimental matrix ‘Central Composite’, originating nine combinations, which were arranged factorially with suppression and without suppression of the pseudostem of the mother

  1. Influence of photon beam energy on the dose enhancement factor caused by gold and silver nanoparticles: An experimental approach

    Energy Technology Data Exchange (ETDEWEB)

    Guidelli, Eder José, E-mail: ederguidelli@pg.ffclrp.usp.br; Baffa, Oswaldo [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP (Brazil)

    2014-03-15

    Purpose: Noble metal nanoparticles have found several medical applications in the areas of radiation detection; x-ray contrast agents and cancer radiation therapy. Based on computational methods, many papers have reported the nanoparticle effect on the dose deposition in the surrounding medium. Here the authors report experimental results on how silver and gold nanoparticles affect the dose deposition in alanine dosimeters containing several concentrations of silver and gold nanoparticles, for five different beam energies, using electron spin resonance spectroscopy (ESR). Methods: The authors produced alanine dosimeters containing several mass percentage of silver and gold nanoparticles. Nanoparticle sizes were measured by dynamic light scattering and by transmission electron microscopy. The authors determined the dose enhancement factor (DEF) theoretically, using a widely accepted method, and experimentally, using ESR spectroscopy. Results: The DEF is governed by nanoparticle concentration, size, and position in the alanine matrix. Samples containing gold nanoparticles afford a DEF higher than 1.0, because gold nanoparticle size is homogeneous for all gold concentrations utilized. For samples containing silver particles, the silver mass percentage governs the nanoparticles size, which, in turns, modifies nanoparticle position in the alanine dosimeters. In this sense, DEF decreases for dosimeters containing large and segregated particles. The influence of nanoparticle size-position is more noticeable for dosimeters irradiated with higher beam energies, and dosimeters containing large and segregated particles become less sensitive than pure alanine (DEF < 1). Conclusions: ESR dosimetry gives the DEF in a medium containing metal nanoparticles, although particle concentration, size, and position are closely related in the system. Because this is also the case as in many real systems of materials containing inorganic nanoparticles, ESR is a valuable tool for

  2. Boron nitride nanoplates supported zero-valent iron nanocomposites for enhanced decolorization of methyl orange with the assistance of ultrasonic irradiation.

    Science.gov (United States)

    Zha, Yiming; Wang, Tianlin

    2016-01-01

    In this work, boron nitride nanoplates (BNNPs) supported nanoscale zero-valent iron (nZVI) was prepared through facile liquid-phase chemical reduction of ferric ion by borohydride under ambient conditions in the presence of BNNPs. The nZVI@BNNPs hybrids were characterized by scanning electron microscopy, X-ray diffraction and magnetic properties measurement. The hybrid material was evaluated for decolorization of a common azo dye, methyl orange (MO), with the assistance of ultrasonic irradiation. Results exhibited that a complete decolorization of 100 mg/L MO was achieved within 6 min using nZVI@BNNPs as the active material. Compared with bare nZVI and BNNPs, nZVI@BNNPs provided a faster reaction process for MO decolorization. The kinetic rate constants of MO decolorization reached 0.8175 min(-1) under ultrasound-assisted condition due to the synergistic effect of ultrasonic irradiation. Fluorescence spectrum experiment confirmed that hydroxyl radicals could be generated in the system combined nZVI with ultrasonic irradiation, and as a result, hydroxyl radicals would contribute to the decolorization process of MO.

  3. Lanthanum and boron co-doped BiVO4 with enhanced visible light photocatalytic activity for degradation of methyl orange

    Institute of Scientific and Technical Information of China (English)

    王敏; 车寅生; 牛超; 党明岩; 董多

    2013-01-01

    BiVO4 photocatalysts co-doped with La and B were prepared by sol-gel method using citric acid as chelate. The samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), Bru-mauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectra (DRS) and the photocatalytic activity was investigated by photo-catalytic degradation of methyl orange (MO). The results showed that boron and lanthanum ions incorporated into the lattice of BiVO4, and co-doping led to more surface oxygen vacancies, high specific surface areas, small crystallite size, narrow band gap and intense light absorbance in visible region. And the doped La(III) ions could help the separation of photogenerated electrons. Com-pared with BiVO4 and B-BiVO4, the photocatalytic activity of La-B co-doped BiVO4 was remarkably improved due to the synergistic effects of the co-doped ions. The degradation rate of MO in 60 min was 98.4%when La doping content was 0.05 mol.%, which was much higher than that of pure BiVO4(20%) and B-BiVO4(37%).

  4. Enhancing the electrochemical oxidation of acid-yellow 36 azo dye using boron-doped diamond electrodes by addition of ferrous ion

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva-Rodriguez, M.; Hernandez-Ramirez, A. [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Peralta-Hernandez, J.M., E-mail: jperalta@fcq.uanl.mx [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Bandala, Erick R.; Quiroz-Alfaro, Marco A. [Universidad de Las Americas - Puebla, Escuela de Ingenieria y Ciencias, Sta. Catarina Martir - Cholula, Puebla 72820 (Mexico)

    2009-08-15

    This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe{sup 2+} (1 mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe{sup 2+} concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe{sup 2+} excess in the system.

  5. Low-dose intra-arterial contrast-enhanced MR aortography in patients based on a theoretically derived injection protocol

    Energy Technology Data Exchange (ETDEWEB)

    Potthast, S.; Bongartz, G.M.; Huegli, R.; Bilecen, D. [University Hospital of Basel, Department of Diagnostic Radiology, Basel (Switzerland); Schulte, A.-C. [University of Basel, Biocenter, Basel (Switzerland); Aschwanden, M. [University of Basel, Department of Angiology, Basel (Switzerland)

    2005-11-01

    Multiple intra-arterial contrast agent injections are necessary during MR-guided endovascular interventions. In respect to the approved limits of maximum daily gadolinium dose, a low-dose injection protocol is mandatory. The objective of this study was to derive and apply a low-dose injection protocol for intra-arterial 3D contrast-enhanced MR aortography in patients. Injection rate (Q{sub inj}), concentration of injected gadolinium [Gd]{sub inj} and aortal blood flow rate (Q{sub blood}) were included for the theoretical evaluation of signal intensity (SI) of the arterial lumen. SI simulations were carried out at Q{sub inj}=2 versus 4 ml/s in the [Gd]{sub inj} range between 0-500 mM. Q{sub inj} and [Gd]{sub inj} with SI above the 75% threshold of the maximal SI were regarded as optimal injection parameters. [Gd]{sub inj}=50 mM and Q{sub inj}=4 ml/s were considered as optimal and were administered in five patients for 3D MR aortography. All images revealed clear delineation of the abdominal aorta and its major branches. Mean{+-}SD of contrast-to-noise ratios of the abdominal aorta, common iliac and renal artery were 70.2{+-}15.2, 58.6{+-}12.3 and 67.4{+-}12.3. Approximately seven intra-aortal injections would be permissible in patients during MR-guided interventions without exceeding the maximal dose of gadolinium. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Meltem Bilici Başkan

    2014-03-01

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

  7. Plasma boron and the effects of boron supplementation in males.

    Science.gov (United States)

    Green, N R; Ferrando, A A

    1994-11-01

    Recently, a proliferation of athletic supplements has been marketed touting boron as an ergogenic aid capable of increasing testosterone. The effect of boron supplementation was investigated in male bodybuilders. Ten male bodybuilders (aged 20 to 26) were given a 2.5-mg boron supplement, while nine male bodybuilders (aged 21 to 27) were given a placebo for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on day 1 and day 49 of the study. A microwave digestion procedure followed by inductively coupled argon plasma spectroscopy was used for boron determination. Twelve subjects had boron values at or above the detection limit with median value of 25 ng/ml (16 ng/ml lower quartile and 33 ng/ml upper quartile). Of the ten subjects receiving boron supplements, six had an increase in their plasma boron. Analysis of variance indicated no significant effect of boron supplementation on any of the other dependent variables. Both groups demonstrated significant increases in total testosterone (p bodybuilding can increase total testosterone, lean body mass, and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all.

  8. Bright prospects for boron

    NARCIS (Netherlands)

    Wassink, J.

    2012-01-01

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

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

    Science.gov (United States)

    Eisler, R.

    1990-01-01

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

  10. Methods of producing continuous boron carbide fibers

    Energy Technology Data Exchange (ETDEWEB)

    Garnier, John E.; Griffith, George W.

    2015-12-01

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

  11. SU-E-T-235: Monte Carlo Analysis of the Dose Enhancement in the Scalp of Patients Due to Titanium Plate Backscatter During Post-Operative Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Hardin, M; Elson, H; Lamba, M [University of Cincinnati, Cincinnati, OH (United States); Wolf, E [Precision Radiotherapy, West Chester, OH (United States); Warnick, R [UC Health Physicians, West Chester, OH (United States)

    2014-06-01

    Purpose: To quantify the clinically observed dose enhancement adjacent to cranial titanium fixation plates during post-operative radiotherapy. Methods: Irradiation of a titanium burr hole cover was simulated using Monte Carlo code MCNPX for a 6 MV photon spectrum to investigate backscatter dose enhancement due to increased production of secondary electrons within the titanium plate. The simulated plate was placed 3 mm deep in a water phantom, and dose deposition was tallied for 0.2 mm thick cells adjacent to the entrance and exit sides of the plate. These results were compared to a simulation excluding the presence of the titanium to calculate relative dose enhancement on the entrance and exit sides of the plate. To verify simulated results, two titanium burr hole covers (Synthes, Inc. and Biomet, Inc.) were irradiated with 6 MV photons in a solid water phantom containing GafChromic MD-55 film. The phantom was irradiated on a Varian 21EX linear accelerator at multiple gantry angles (0–180 degrees) to analyze the angular dependence of the backscattered radiation. Relative dose enhancement was quantified using computer software. Results: Monte Carlo simulations indicate a relative difference of 26.4% and 7.1% on the entrance and exit sides of the plate respectively. Film dosimetry results using a similar geometry indicate a relative difference of 13% and -10% on the entrance and exit sides of the plate respectively. Relative dose enhancement on the entrance side of the plate decreased with increasing gantry angle from 0 to 180 degrees. Conclusion: Film and simulation results demonstrate an increase in dose to structures immediately adjacent to cranial titanium fixation plates. Increased beam obliquity has shown to alleviate dose enhancement to some extent. These results are consistent with clinically observed effects.

  12. Plasma immersion ion implantation of boron for ribbon silicon solar cells

    Directory of Open Access Journals (Sweden)

    Derbouz K.

    2013-09-01

    Full Text Available In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 1015 to 1016 cm-2, then activated by a thermal annealing in a conventional furnace at 900 and 950 °C for 30 min. The n+ region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5 × 1015 cm-2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

  13. Plasma immersion ion implantation of boron for ribbon silicon solar cells

    Science.gov (United States)

    Derbouz, K.; Michel, T.; De Moro, F.; Spiegel, Y.; Torregrosa, F.; Belouet, C.; Slaoui, A.

    2013-09-01

    In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template) using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 1015 to 1016 cm-2, then activated by a thermal annealing in a conventional furnace at 900 and 950 °C for 30 min. The n+ region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD) or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5 × 1015 cm-2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

  14. Regioselective silylation of pyranosides using a boronic acid/Lewis base co-catalyst system.

    Science.gov (United States)

    Lee, Doris; Taylor, Mark S

    2013-09-07

    The combination of a boronic acid and a Lewis base, both employed in substoichiometric amounts, enables the regioselective silylation of cis-diol groups in alkylpyranoside substrates. The proposed mode of activation involves the formation of a tetracoordinate adduct that displays enhanced nucleophilicity at the boron-bound alkoxide groups.

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

    OpenAIRE

    Chaoyu He; J. X. Zhong

    2013-01-01

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

  16. Exogenous low-dose hydrogen peroxide enhances drought tolerance of soybean (Glycine max L.) through inducing antioxidant system.

    Science.gov (United States)

    Guler, Neslihan Saruhan; Pehlivan, Necla

    2016-06-01

    Hydrogen peroxide (H(2)O(2)) functions as a signal molecule in plants under abiotic and biotic stress. In this study, the role of exogenous H(2)O(2) in improving drought tolerance in two soybean cultivars (Glycine max L. Merrill) differing in their tolerance to drought was evaluated. Plants were grown in plastic pots with normal irrigation in a phytotron. Four weeks after radicle emergence, either 1 mM H(2)O(2) or distilled water was sprayed as foliar onto the leaves of each plant, after drought stress was applied. Leaf samples were harvested on the 4(th) and 7(th) days of the drought. Antioxidant-related enzyme activity, such as the superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) content was measured during the drought period. Drought stress decreased leaf water potential, relative water content and photosynthetic pigment content but enhanced lipid peroxidation and endogenous H(2)O(2) concentration. By contrast, exogenous low dose H(2)O(2) improved water status, pigment content and lipid peroxidation under drought stress. Endogenous H(2)O(2) concentration was reduced by exogenous H(2)O(2) as compared to drought treatment alone. H(2)O(2) pre-treatment induced all the antioxidant enzyme activities, to a greater extent than the control leaves, during drought. H(2)O(2) pretreatment further enhanced the activities of antioxidant enzymes in the tolerant cultivar compared to the sensitive cultivar. Results suggested that low dose H(2)O(2) pre-treatment alleviated water loss and H(2)O(2) content and increased drought stress tolerance by inducing the antioxidant system.

  17. Enhancement of energy expenditure following a single oral dose of flavan-3-ols associated with an increase in catecholamine secretion.

    Directory of Open Access Journals (Sweden)

    Yusuke Matsumura

    Full Text Available Numerous clinical studies have reported that ingestion of chocolate reduces the risk of metabolic syndrome. However, the mechanisms by which this occurs remain unclear. In this murine study, the metabolic-enhancing activity of a 10 mg/kg mixture of flavan-3-ol fraction derived from cocoa (FL was compared with the same single dose of (--epicatechin (EC. Resting energy expenditure (REE was significantly increased in mice treated with the FL versus the group administered the distilled water vehicle (Cont during periods of ad libitum feeding and fasting. Mice were euthanized under the effect of anesthesia 2, 5, and 20 hr after treatment with FL or Cont while subsequently fasting. The mRNA levels of the uncoupling protein-1 (UCP-1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α in brown adipose tissue (BAT were significantly increased 2 hr after administration of FL. UCP-3 and PGC-1α in the gastrocnemius were significantly increased 2 and 5 hr after administration of the FL. The concentrations of phosphorylated AMP-activated protein kinase (AMPK 1α were found to be significant in the gastrocnemius of mice 2 and 5 hr after ingesting FL. However, these changes were not observed following treatment with EC. Plasma was collected for measurement of catecholamine levels in other animals euthanized by decapitation 2 and 4 hr after their respective group treatment. Plasma adrenaline level was significantly elevated 2 hr after treatment with FL; however, this change was not observed following the administration of EC alone. The present results indicated that FL significantly enhanced systemic energy expenditure, as evidenced by an accompanying increase in the type of gene expression responsible for thermogenesis and lipolysis, whereas EC exhibited this less robustly or effectively. It was suggested the possible interaction between thermogenic and lipolytic effects and the increase in plasma catecholamine concentrations

  18. Ultra low-dose of gadobenate dimeglumine for late gadolinium enhancement (LGE) imaging in acute myocardial infarction: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Galea, Nicola, E-mail: nicola.galea@uniroma1.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Francone, Marco, E-mail: marco.francone@uniroma1.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Zaccagna, Fulvio, E-mail: f.zaccagna@gmail.com [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Ciolina, Federica, E-mail: federica.ciolina@gmail.com [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Cannata, David, E-mail: davidrum@yahoo.it [Department of Radiological Sciences, Pathology and Oncology, Policlinico Umberto I, “Sapienza” University of Rome, Viale Regina Elena 315, 00161 Rome (Italy); Algeri, Emanuela, E-mail: emanuela_algeri@yahoo.com [Service de Radiologie et Imagerie Cardiovasculaire, Hôpital Cardiologique, Centre Hospitalier Régional et Universitaire de Lille, Avenue Oscar Lambret, 59037 Lille Cedex (France); Agati, Luciano, E-mail: luciano.agati@uniroma1.it [Department of Cardiovascular, Respiratory, Nephrologic, Anestesiologic and Geriatric Sciences, Sapienza University of Rome, Policlinico Umberto I, Via del Policlinico 165, 00161 Rome, Rome (Italy); and others

    2014-12-15

    Highlights: • We compared two gadolinium dose for late enhancement imaging in acute infarction. • We evaluated image quality both qualitatively and quantitatively. • Low dose regimen is feasible and provides better image quality at 5–10 min delay. • Standard dose warrants better image quality and should be routinely preferred. - Abstract: Purpose: To assess the feasibility of using an ultra-low dose (0.05 mmol/kg of body weight [BW]) of high relaxivity contrast agent for late gadolinium enhancement (LGE) imaging in patients with acute myocardial infarction (AMI). Materials and methods: 17 consecutive patients (mean age, 60.1 ± 10.3 years) with ST-segment elevation AMI underwent two randomized cardiac magnetic resonance studies (exam intervals between 24 and 48 h) on a 1.5 T unit during the first week after the event using gadobenate dimeglumine (Gd-BOPTA) at the dose of 0.1 mmol/kg BW (standard dose or SD group) and 0.05 mmol/kg BW (half dose or HD group). Image quality was qualitatively assessed. Quantitative analysis of LGE were performed by measuring signal intensity (SI), signal-to-noise ratio (SNR) in the infarcted myocardium (IM), non-infarcted myocardium (N-IM) and left ventricular cavity (LVC) in images acquired at 1, 3, 5, 10, 15 and 20 min after administration of Gd-BOPTA using both contrast media protocol. Contrast-to-noise ratio (CNR) between IM and N-IM (CNR IM/N-IM) and between IM and LVC (CNR IM/LVC) were also quantified for each time point. Moreover the extent of infarcted myocardium was measured. Results: 102 LGE images were evaluated for each dose group. Quality score was significantly higher for SD at 1, 15 and 20 min (0.002 < p < 0.046) and for HD at 5 min (p = 0.013). SNR has been higher in the SD group compared to the HD group even though not statistically significant at any time-point for both IM (SD vs. HD: 87.7 ± 73 vs. 65 ± 66; 0.15 < p < 0.38) and N-IM (SD vs. HD: 22 ± 61 vs. 9.9 ± 6.5; 0.09 < p < 0.43). LVC SNR was

  19. Comparison of Delayed Gadolinium-Enhanced MRI with Magnetization Transfer after Injection of Single-Dose and Immediate Image without MT after Injection of Double Dose Gadolinium Chelates for Detecting

    Directory of Open Access Journals (Sweden)

    Ahmad Alizadeh

    2010-05-01

    Full Text Available Background/Objective: To determine whether the use of single dose gadolinium chelate in combination of MTC and delay of 20-30 minute brain imaging is useful in detecting MS lesions."nPatients and Methods: T1W spin echo images with and without MTC were obtained before contrast administration followed by T1W images with MTC starting and 20-30 minutes after contrast administration. After 24-72 hours T1W images without MTC were obtained immediately after injection of 0.2 mmol/Kg contrast material. All images were evaluated in a blinded route by two readers. Outcome parameters included the number of enhancing lesions."nResults: Single dose in combination with MTC and delay of 20-30 minutes showed 16 enhancing lesions and double dose showed 44. Differences between the two methods were significant (p=0.003. Thirteen lesions enhanced with both methods."nConclusion: The use of single dose in combination with MTC and delay of 20-30 minutes enables us to detect an increase of enhancing lesions."nKeywords: Magnetic Resonance, Magnetization Transfer, Multiple Sclerosis, Delay

  20. Low-dose methotrexate enhances cycling of highly anaplastic cancer cells

    Science.gov (United States)

    Marzi, Ilaria; Olivotto, Massimo

    2017-01-01

    ABSTRACT We previously showed that cellular RedOx state governs the G1-S transition of AH130 hepatoma, a tumor spontaneously reprogrammed to the embryonic stem cell stage. This transition is impaired when the mithocondrial electron transport system is blocked by specific inhibitors (antimycin A) or the respiratory chain is saturated by adding to the cells high concentrations of pyruvate. The antimycin A or pyruvate block is removed by the addition of adequate concentrations of folate (F). This suggests that the G1-S transition of AH130 cells depends on a respiration-linked step of DNA synthesis related to folate metabolism. In the study reported here, we characterized the effects of methotrexate (MTX), an inhibitor of dihydofolate-reductase, on the G1-S transition of hepatoma cells, in the absence or the presence of exogenously added F, dihydrofolate (FH2) or tetrahydrofolate (FH4). MTX, at 1 μM or higher concentrations, inhibited G1-S transition. This inhibition was completely removed by exogenous folates. Surprisingly, 10 nM MTX stimulated G1-S transition. The addition of F, but not FH2 or FH4, significantly increased this effect. Furthermore, 10 nM MTX removed the block of the G1-S transition operated by antimycin A or pyruvate, an effect which was enhanced in the presence of F. Finally, the stimulatory effect of 10 nM MTX was inhibited in the presence of serine. Our findings indicated that, under certain conditions, MTX may stimulate, rather than inhibiting, the cycling of cancer cells exhibiting a stem cell-like phenotype, such as AH130 cells. This may impact the therapeutic use of MTX and of folates as supportive care. PMID:27841718

  1. Fivefold twinned boron carbide nanowires.

    Science.gov (United States)

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

    2009-09-01

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

  2. Quantitative analysis of proton boron fusion therapy (PBFT) in various conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Joo-Young; Yoon, Do-Kun; Suh, Tae Suk [College of Medicine, Catholic University of Korea, Seoul (Korea, Republic of)

    2015-05-15

    From the theoretical point of view, the PBFT has some strong advantages over currently existing radiotherapy methods. First, boron-based tumor targeting is required prior to performing the treatments such as boron-neutron capture therapy (BNCT). Tumor targeting should be performed before the BNCT by injecting the boronate compound. If boron is not taken up by the normal tissue, the normal tissue can be spared the irradiation by alpha particles. When boron uptake occurs in the target region, selective therapy is possible by neutron capture reaction of labeled boron particles in the target region. Likewise, when boron is distributed in the tumor region for the PBFT, the proposed method can represent a more critical discriminative therapy than either the BNCT or conventional particle therapy. In the conventional proton therapy, in order to deliver a dose to a tumor, the proton beam energy has to be adjusted along the tumor region (e.g., shape and depth). The proton therapy aims at delivering the maximal dose to the tumor by using protons only. In this study, the effectiveness of the PBFT with respect to several physical parameters was evaluated quantitatively by using Monte Carlo simulations. We confirmed that the PBFT can be used to perform critical discriminative therapy. Also, the results of our studies can be used for constructing the PFBT dose database that can be utilized in treatment planning systems (TPSs)

  3. 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.

  4. Solar Variability and the Near-Earth Environment: Mining Enhanced Low Dose Rate Sensitivity Data From the Microelectronics and Photonics Test Bed Space Experiment

    Science.gov (United States)

    Turflinger, T.; Schmeichel, W.; Krieg, J.; Titus, J.; Campbell, A.; Reeves, M.; Marshall (P.); Hardage, Donna (Technical Monitor)

    2004-01-01

    This effort is a detailed analysis of existing microelectronics and photonics test bed satellite data from one experiment, the bipolar test board, looking to improve our understanding of the enhanced low dose rate sensitivity (ELDRS) phenomenon. Over the past several years, extensive total dose irradiations of bipolar devices have demonstrated that many of these devices exhibited ELDRS. In sensitive bipolar transistors, ELDRS produced enhanced degradation of base current, resulting in enhanced gain degradation at dose rates 1 rd(Si)/s. This Technical Publication provides updated information about the test devices, the in-flight experiment, and both flight-and ground-based observations. Flight data are presented for the past 5 yr of the mission. These data are compared to ground-based data taken on devices from the same date code lots. Information about temperature fluctuations, power shutdowns, and other variables encountered during the space flight are documented.

  5. Biodistribution of Amine-Amide Chlorin e6 Derivative Conjugate with a Boron Nanoparticle for Boron Neutron-Capture Therapy

    OpenAIRE

    А.B. Volovetsky; N.Y. Shilyagina; V.V. Dudenkova; S.О. Pasynkova; М.А. Grin; А.F. Mironov; А.V. Feofanov; I.V. Balalaeva; А.V. Maslennikova

    2016-01-01

    The aim of the investigation was to study the biodistribution of amino-amide chlorin e6 derivative conjugate with cobalt bis-dicarbollide as a potential boron transporter for the tasks of boron neutron-capture therapy. Materials and Methods. The experiments were carried out on Balb/c mice with induced murine colon carcinoma CT-26. Amino-amide chlorin e6 derivative conjugate with cobalt bis-dicarbollide was administered intravenously, the dose being 5 and 10 mg/kg body mass. The sampling for m...

  6. Surface diffusivity of atomic deuterium on Ni3(Al, Ti)(110) surface with and without boron

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The electron-stimulated desorption was used to measure the surface diffusivity of at omic deuterium on clean and boron-modified Ni3(Al, Ti)(110) surfaces. Boron dosing was performed using a solid-state boronion source. Earlier studies showed that boron dissociates water readily at temperatures as low as 130 Kand that the resulting atomic hydrogen is bound to the surface strongly. The surface diffusi on coefficient of atomic D on 0.05 monolayer boron-modified surface was measured to be about 10 times smaller than that on the clean surface. This slower diffu sion of atomic hydrogen may explain why boron improves the ductility of polycrys talline Ni3Al in moist environments.

  7. Effect of Nitrogen and Boron in Seed Yield and Yield Attributing Characters of Broccoli

    Directory of Open Access Journals (Sweden)

    A. Khanal

    2015-09-01

    Full Text Available Plant nutrient is one of the limiting factors affecting crop production. Nitrogen and boron are major nutrients in case of broccoli. So, an experiment was carried out to evaluate the effect of nitrogen and boron in seed yield and yield attributing characters of broccoli in Rampur, Chitwan during winter season. The experiment was laid out in factorial RCBD design with four levels of nitrogen and two levels of boron. Each plot consists of 25 plants which were separated by 60 * 60 cm spacing. There are altogether eight treatments replicates thrice. Local variety Calabrese was used. Significant effect of different dose of nitrogen and boron on yield attributing characters was found. Also interactive effect of nitrogen and boron in number of pods, pod length, seed yield and number of seeds per pod was found significantly different.

  8. Supraphysiological Doses of Performance Enhancing Anabolic-Androgenic Steroids Exert Direct Toxic Effects on Neuron-like Cells

    Directory of Open Access Journals (Sweden)

    John Robert Basile

    2013-05-01

    Full Text Available Anabolic-androgenic steroids (AAS are lipophilic hormones often taken in excessive quantities by athletes and bodybuilders to enhance performance and increase muscle mass. AAS exert well known toxic effects on specific cell and tissue types and organ systems. The attention that androgen abuse has received lately should be used as an opportunity to educate both athletes and the general population regarding their adverse effects. Among numerous commercially available steroid hormones, very few have been specifically tested for direct neurotoxicity. We evaluated the effects of supraphysiological doses of methandienone and 17-α-methyltestosterone on sympathetic-like neuron cells. Vitality and apoptotic effects were analyzed, and immunofluorescence staining and western blot performed. In this study, we demonstrate that exposure of supraphysiological doses of methandienone and 17-α-methyltestosterone are toxic to the neuron-like differentiated pheochromocytoma cell line PC12, as confirmed by toxicity on neurite networks responding to nerve growth factor and the modulation of the survival and apoptosis-related proteins ERK, caspase-3, poly (ADP-ribose polymerase and heat-shock protein 90. We observe, in contrast to some previous reports but in accordance with others, expression of the androgen receptor (AR in neuron-like cells, which when inhibited mitigated the toxic effects of AAS tested, suggesting that the AR could be binding these steroid hormones to induce genomic effects. We also note elevated transcription of neuritin in treated cells, a neurotropic factor likely expressed in an attempt to resist neurotoxicity. Taken together, these results demonstrate that supraphysiological exposure to the AAS methandienone and 17-α-methyltestosterone exert neurotoxic effects by an increase in the activity of the intrinsic apoptotic pathway and alterations in neurite networks.

  9. Dual-energy contrast-enhanced breast tomosynthesis: optimization of beam quality for dose and image quality.

    Science.gov (United States)

    Samei, Ehsan; Saunders, Robert S

    2011-10-07

    Dual-energy contrast-enhanced breast tomosynthesis is a promising technique to obtain three-dimensional functional information from the breast with high resolution and speed. To optimize this new method, this study searched for the beam quality that maximized image quality in terms of mass detection performance. A digital tomosynthesis system was modeled using a fast ray-tracing algorithm, which created simulated projection images by tracking photons through a voxelized anatomical breast phantom containing iodinated lesions. The single-energy images were combined into dual-energy images through a weighted log subtraction process. The weighting factor was optimized to minimize anatomical noise, while the dose distribution was chosen to minimize quantum noise. The dual-energy images were analyzed for the signal difference to noise ratio (SdNR) of iodinated masses. The fast ray-tracing explored 523 776 dual-energy combinations to identify which yields optimum mass SdNR. The ray-tracing results were verified using a Monte Carlo model for a breast tomosynthesis system with a selenium-based flat-panel detector. The projection images from our voxelized breast phantom were obtained at a constant total glandular dose. The projections were combined using weighted log subtraction and reconstructed using commercial reconstruction software. The lesion SdNR was measured in the central reconstructed slice. The SdNR performance varied markedly across the kVp and filtration space. Ray-tracing results indicated that the mass SdNR was maximized with a high-energy tungsten beam at 49 kVp with 92.5 µm of copper filtration and a low-energy tungsten beam at 49 kVp with 95 µm of tin filtration. This result was consistent with Monte Carlo findings. This mammographic technique led to a mass SdNR of 0.92 ± 0.03 in the projections and 3.68 ± 0.19 in the reconstructed slices. These values were markedly higher than those for non-optimized techniques. Our findings indicate that dual

  10. Enhanced cytotoxicity and decreased CD8 dependence of human cancer-specific cytotoxic T lymphocytes after vaccination with low peptide dose.

    Science.gov (United States)

    Lövgren, Tanja; Baumgaertner, Petra; Wieckowski, Sébastien; Devêvre, Estelle; Guillaume, Philippe; Luescher, Immanuel; Rufer, Nathalie; Speiser, Daniel E

    2012-06-01

    In mice, vaccination with high peptide doses generates higher frequencies of specific CD8+ T cells, but with lower avidity compared to vaccination with lower peptide doses. To investigate the impact of peptide dose on CD8+ T cell responses in humans, melanoma patients were vaccinated with 0.1 or 0.5 mg Melan-A/MART-1 peptide, mixed with CpG 7909 and Incomplete Freund's adjuvant. Neither the kinetics nor the amplitude of the Melan-A-specific CD8+ T cell responses differed between the two vaccination groups. Also, CD8+ T cell differentiation and cytokine production ex vivo were similar in the two groups. Interestingly, after low peptide dose vaccination, Melan-A-specific CD8+ T cells showed enhanced degranulation upon peptide stimulation, as assessed by CD107a upregulation and perforin release ex vivo. In accordance, CD8+ T cell clones derived from low peptide dose-vaccinated patients showed significantly increased degranulation and stronger cytotoxicity. In parallel, Melan-A-specific CD8+ T cells and clones from low peptide dose-vaccinated patients expressed lower CD8 levels, despite similar or even stronger binding to tetramers. Furthermore, CD8+ T cell clones from low peptide dose-vaccinated patients bound CD8 binding-deficient tetramers more efficiently, suggesting that they may express higher affinity TCRs. We conclude that low peptide dose vaccination generated CD8+ T cell responses with stronger cytotoxicity and lower CD8 dependence.

  11. High-Dose Neutron Detector Development Using 10B Coated Cells

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-08

    During FY16 the boron-lined parallel-plate technology was optimized to fully benefit from its fast timing characteristics in order to enhance its high count rate capability. To facilitate high count rate capability, a novel fast amplifier with timing and operating properties matched to the detector characteristics was developed and implemented in the 8” boron plate detector that was purchased from PDT. Each of the 6 sealed-cells was connected to a fast amplifier with corresponding List mode readout from each amplifier. The FY16 work focused on improvements in the boron-10 coating materials and procedures at PDT to significantly improve the neutron detection efficiency. An improvement in the efficiency of a factor of 1.5 was achieved without increasing the metal backing area for the boron coating. This improvement has allowed us to operate the detector in gamma-ray backgrounds that are four orders of magnitude higher than was previously possible while maintaining a relatively high counting efficiency for neutrons. This improvement in the gamma-ray rejection is a key factor in the development of the high dose neutron detector.

  12. Low-dose spinal neostigmine further enhances the analgesic effect of spinal bupivacaine combined with epidural dexamethasone, following orthopedic surgery

    Directory of Open Access Journals (Sweden)

    Gabriela Rocha Lauretti

    2014-01-01

    Full Text Available Background: Opioids are considered mainstream for combined spinal-epidural anesthesia, but frequently limited by adverse effects. The aim of this study was to examine whether low-dose spinal neostigmine, epidural dexamethasone or their combination enhances analgesia from spinal bupivacaine without adverse effects. Materials and Methods : A total of 60 patients undergoing orthopedic surgery were randomized to one of four groups and evaluated for 24-h after surgery for analgesia (time to first rescue analgesic and rescue analgesic consumption. Patients received 15 mg bupivacaine plus the test drug intrathecally (saline or 1 microgram (μg neostigmine. The epidural test drug was either saline or 10 mg dexamethasone. The Control group (CG received spinal and epidural saline. The Neostigmine group (NG, spinal neostigmine and epidural saline; the Dexamethasone group (DG, spinal saline and epidural dexamethasone; and the Neostigmine-dexamethasone group (NDG, spinal neostigmine and epidural dexamethasone. Results: The CG (282 ± 163 min and NG (524 ± 142 min were similar in their times to first rescue analgesic and analgesic consumption. The time to first rescue analgesic was longer for the DG (966 ± 397 min compared with CG and NG (P < 0.0002, and the DG had less ketoprofen consumption and lower overall visual analogue scale-pain sores compared with CG and NG (P < 0.0005. Addition of 1 mg-neostigmine (NDG resulted in longer time to rescue analgesic (1205 ± 303 min; P < 0.02 and lower ketoprofen consumption (P < 0.05 compared to DG. Sporadic cases of vesical catheterization and emesis were observed, however adverse effects were similar among groups. Conclusion: Spinal 1 microgram (μg neostigmine further enhanced analgesia from spinal bupivacaine combined with epidural dexamethasone, without increasing the incidence of adverse effects.

  13. Functionalized boron nitride nanotubes

    Science.gov (United States)

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

    2014-04-22

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

  14. Semiconducting boron carbides with better charge extraction through the addition of pyridine moieties

    Science.gov (United States)

    Echeverria, Elena; Dong, Bin; Peterson, George; Silva, Joseph P.; Wilson, Ethiyal R.; Sky Driver, M.; Jun, Young-Si; Stucky, Galen D.; Knight, Sean; Hofmann, Tino; Han, Zhong-Kang; Shao, Nan; Gao, Yi; Mei, Wai-Ning; Nastasi, Michael; Dowben, Peter A.; Kelber, Jeffry A.

    2016-09-01

    The plasma-enhanced chemical vapor (PECVD) co-deposition of pyridine and 1,2 dicarbadodecaborane, 1,2-B10C2H12 (orthocarborane) results in semiconducting boron carbide composite films with a significantly better charge extraction than plasma-enhanced chemical vapor deposited semiconducting boron carbide synthesized from orthocarborane alone. The PECVD pyridine/orthocarborane based semiconducting boron carbide composites, with pyridine/orthocarborane ratios ~3:1 or 9:1 exhibit indirect band gaps of 1.8 eV or 1.6 eV, respectively. These energies are less than the corresponding exciton energies of 2.0 eV-2.1 eV. The capacitance/voltage and current/voltage measurements indicate the hole carrier lifetimes for PECVD pyridine/orthocarborane based semiconducting boron carbide composites (3:1) films of ~350 µs compared to values of  ⩽35 µs for the PECVD semiconducting boron carbide films fabricated without pyridine. The hole carrier lifetime values are significantly longer than the initial exciton decay times in the region of ~0.05 ns and 0.27 ns for PECVD semiconducting boron carbide films with and without pyridine, respectively, as suggested by the time-resolved photoluminescence. These data indicate enhanced electron-hole separation and charge carrier lifetimes in PECVD pyridine/orthocarborane based semiconducting boron carbide and are consistent with the results of zero bias neutron voltaic measurements indicating significantly enhanced charge collection efficiency.

  15. Boron neutron capture therapy (BNCT): implications of neutron beam and boron compound characteristics.

    Science.gov (United States)

    Wheeler, F J; Nigg, D W; Capala, J; Watkins, P R; Vroegindeweij, C; Auterinen, I; Seppälä, T; Bleuel, D

    1999-07-01

    The potential efficacy of boron neutron capture therapy (BNCT) for malignant glioma is a significant function of epithermal-neutron beam biophysical characteristics as well as boron compound biodistribution characteristics. Monte Carlo analyses were performed to evaluate the relative significance of these factors on theoretical tumor control using a standard model. The existing, well-characterized epithermal-neutron sources at the Brookhaven Medical Research Reactor (BMRR), the Petten High Flux Reactor (HFR), and the Finnish Research Reactor (FiR-1) were compared. Results for a realistic accelerator design by the E. O. Lawrence Berkeley National Laboratory (LBL) are also compared. Also the characteristics of the compound p-Boronophenylaline Fructose (BPA-F) and a hypothetical next-generation compound were used in a comparison of the BMRR and a hypothetical improved reactor. All components of dose induced by an external epithermal-neutron beam fall off quite rapidly with depth in tissue. Delivery of dose to greater depths is limited by the healthy-tissue tolerance and a reduction in the hydrogen-recoil and incident gamma dose allow for longer irradiation and greater dose at a depth. Dose at depth can also be increased with a beam that has higher neutron energy (without too high a recoil dose) and a more forward peaked angular distribution. Of the existing facilities, the FiR-1 beam has the better quality (lower hydrogen-recoil and incident gamma dose) and a penetrating neutron spectrum and was found to deliver a higher value of Tumor Control Probability (TCP) than other existing beams at shallow depth. The greater forwardness and penetration of the HFR the FiR-1 at greater depths. The hypothetical reactor and accelerator beams outperform at both shallow and greater depths. In all cases, the hypothetical compound provides a significant improvement in efficacy but it is shown that the full benefit of improved compound is not realized until the neutron beam is fully

  16. Design for an accelerator-based orthogonal epithermal neutron beam for boron neutron capture therapy.

    Science.gov (United States)

    Allen, D A; Beynon, T D; Green, S

    1999-01-01

    This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). In particular, the option of producing a therapy beam at an orthogonal direction to the incoming protons is considered. Monte Carlo radiation transport simulations, both with and without a head phantom, have shown that an orthogonal beam geometry is not only acceptable but is indeed beneficial, in terms of a lower mean neutron energy and an enhanced therapeutic ratio for the same useful neutron fluence in the therapy beam. Typical treatment times for various beam options have been calculated, and range from 20 to 48 min with a 5 mA beam of 2.8 MeV protons, if the maximum photon-equivalent dose delivered to healthy tissue is to be 12.6 Gy Eq. The effects of proton beam diameter upon the therapy beam parameters have also been considered.

  17. Rapid accurate isotopic measurements on boron in boric acid and boron carbide.

    Science.gov (United States)

    Duchateau, N L; Verbruggen, A; Hendrickx, F; De Bièvre, P

    1986-04-01

    A procedure is described whereby rapid and accurate isotopic measurements can be performed on boron in boric acid and boron carbide after fusion of these compounds with calcium carbonate. It allows the determination of the isotopic composition of boron in boric acid and boron carbide and the direct assay of boron or the (10)B isotope in boron carbide by isotope-dilution mass spectrometry.

  18. Dosimetric effects of beam size and collimation of epithermal neutrons for boron neutron capture therapy.

    Science.gov (United States)

    Yanch, J C; Harling, O K

    1993-08-01

    A series of studies of "ideal" beams has been carried out using Monte Carlo simulation with the goal of providing guidance for the design of epithermal beams for boron neutron capture therapy (BNCT). An "ideal" beam is defined as a monoenergetic, photon-free source of neutrons with user-specified size, shape and angular dependence of neutron current. The dosimetric behavior of monoenergetic neutron beams in an elliptical phantom composed of brain-equivalent material has been assessed as a function of beam diameter and neutron emission angle (beam angle), and the results are reported here. The simulation study indicates that substantial differences exist in the dosimetric behavior of small and large neutron beams (with respect to the phantom) as a function of the extent of beam collimation. With a small beam, dose uniformity increases as the beam becomes more isotropic (less collimated); the opposite is seen with large beams. The penetration of thermal neutrons is enhanced as the neutron emission angle is increased with a small beam; again the opposite trend is seen with large beams. When beam size is small, the dose delivered per neutron is very dependent on the extent of beam collimation; this does not appear to be the case with a larger beam. These trends in dose behavior are presented graphically and discussed in terms of their effect on several figures of merit, the advantage depth, the advantage ratio, and the advantage depth-dose rate. Tables giving quick summaries of these results are provided.

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Pretreatment of plant and soil samples: a problem in boron analysis. Part I. Plants

    Energy Technology Data Exchange (ETDEWEB)

    Wikner, B.

    1986-01-01

    Possible sources of errors in the determination of boron in plant samples were examined. During drying and grinding neither loss nor contamination of boron was observed. It was found that boron was slightly lost when muffling at temperatures higher than 550/sup 0/C. The addition of Ca(OH)/sub 2/ prevented the loss but gave rise to incomplete ashing in many cases. Nitrate salts added in order to enhance oxidation gave rise to boron loss. Wet ashing should be done preferably in a concentrated sulfuric acid or phosphoric acid medium at low temperatures. At higher temperatures the shape of the digestion flask is important - long neck flasks are usually safe enough due to their condensating effects. Very high temperatures with foaming demand additional cooling condensors. Borosilicate glass can not be used. Extraction of plant samples with hydrochloric acid is a convenient alternative but no more than 75-94% of the total boron concentration in plants could be extracted.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-03

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

  2. Silver Nanoparticle-Deposited Boron Nitride Nanosheets as Fillers for Polymeric Composites with High Thermal Conductivity.

    Science.gov (United States)

    Wang, Fangfang; Zeng, Xiaoliang; Yao, Yimin; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2016-01-19

    Polymer composites with high thermal conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward higher speed and performance. However, a common method to enhance polymer thermal conductivity through an addition of high thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the thermal conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The thermal conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured thermal conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower thermal contact resistance among boron nitride nanosheets' interfaces. The finding sheds new light on enhancement of thermal conductivity of the polymeric composites which concurrently require the electrical insulation.

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

    Energy Technology Data Exchange (ETDEWEB)

    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).

  4. 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...

  5. Influence of nanocrystalline boron precursor powder on superconductivity in MgB2 bulk.

    Science.gov (United States)

    Zhang, Yun; Lu, Cheng; Zhou, Sihai; Joo, Jinho

    2009-12-01

    In this report, high-purity nanocrystalline boron powders processed by ball-milling were used as the precursor powders to fabricate MgB2 superconductor. The transport properties and the critical current density in the samples made from ball-milled boron powders and as-supplied boron powders were investigated. It was found that the ball-milled boron powders led to a significant enhancement of the critical current density in MgB2 sintered at 650 degrees C. The reason can be attributed to the small MgB2 grain size caused by the ball-milled boron precursor powders. The resistivity of the samples made from the ball-milled boron powder was lower than that of the sample from as-supplied boron powder. As the sintering temperature increased, both resistivity and upper critical field decreased in the samples using the ball-milled boron powders as a precursor. Poor connectivity and large strain are responsible for the high resistivity.

  6. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

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

    2013-12-01

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

  7. Utilizing a novel tandem oral dosing strategy to enhance exposure of low-solubility drug candidates in a preclinical setting.

    Science.gov (United States)

    Chiang, Po-Chang; South, Sarah A; Foster, Kimberly A; Daniels, J Scott; Wene, Steve P; Albin, Lesley A; Thompson, David C

    2010-07-01

    Time and resource constraints necessitate increasingly early decision making to accelerate or stop preclinical drug discovery programs. Early discovery drug candidates may be potent inhibitors of new targets, but all too often exhibit poor pharmaceutical and pharmacokinetic properties that limit the in vivo exposure. Low solubility of a drug candidate often leads to poor oral bioavailability and poor dose linearity that creates an issue for efficacy and target safety studies, where high drug exposures are desired. When solubility issues are encountered, enabling formulations are often used to improve the exposure. However, this approach often requires a substantial and lengthy investment to develop the formulation. In our study, two drug candidates with poor aqueous solubility were dosed in rats as simple suspension formulations using a novel tandem dosing strategy, which employs dosing orally in 2.5 h increments up to three times to simulate an oral infusion by avoiding saturation of absorption associated with bolus dosing. These compounds were also dosed using the same suspension formulations and a standard dosing strategy. The resulting in vivo exposures were compared. It was found that this novel tandem dosing strategy significantly improved the in vivo exposures.

  8. Dose optimization for dual-energy contrast-enhanced digital mammography based on an energy-resolved photon-counting detector: A Monte Carlo simulation study

    Science.gov (United States)

    Lee, Youngjin; Lee, Seungwan; Kang, Sooncheol; Eom, Jisoo

    2017-03-01

    Dual-energy contrast-enhanced digital mammography (CEDM) has been used to decompose breast images and improve diagnostic accuracy for tumor detection. However, this technique causes an increase of radiation dose and an inaccuracy in material decomposition due to the limitations of conventional X-ray detectors. In this study, we simulated the dual-energy CEDM with an energy-resolved photon-counting detector (ERPCD) for reducing radiation dose and improving the quantitative accuracy of material decomposition images. The ERPCD-based dual-energy CEDM was compared to the conventional dual-energy CEDM in terms of radiation dose and quantitative accuracy. The correlation between radiation dose and image quality was also evaluated for optimizing the ERPCD-based dual-energy CEDM technique. The results showed that the material decomposition errors of the ERPCD-based dual-energy CEDM were 0.56-0.67 times lower than those of the conventional dual-energy CEDM. The imaging performance of the proposed technique was optimized at the radiation dose of 1.09 mGy, which is a half of the MGD for a single view mammogram. It can be concluded that the ERPCD-based dual-energy CEDM with an optimal exposure level is able to improve the quality of material decomposition images as well as reduce radiation dose.

  9. Combustion of boron containing compositions

    Energy Technology Data Exchange (ETDEWEB)

    Frolov, Y.; Pivkina, A. [Institute of Chemical Physics, Russian Academy of Science, Moscow (Russian Federation)

    1996-12-31

    Boron is one of the most energetic components for explosives, propellants and for heterogeneous condensed systems in common. The combustion process of mixtures of boron with different oxidizers was studied. The burning rate, concentration combustion limits, the agglomeration and dispersion processes during reaction wave propagation were analysed in the respect of the percolation theory. The linear dependence of the burning rate on the contact surface value was demonstrated. The percolative model for the experimental results explanation is proposed. (authors) 5 refs.

  10. Boron diffusion in silicon devices

    Science.gov (United States)

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

    2010-09-07

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

  11. A study on a dental device for the prevention of mucosal dose enhancement caused by backscatter radiation from dental alloy during external beam radiotherapy.

    Science.gov (United States)

    Katsura, Kouji; Utsunomiya, Satoru; Abe, Eisuke; Sakai, Hironori; Kushima, Naotaka; Tanabe, Satoshi; Yamada, Takumi; Hayakawa, Takahide; Yamanoi, Yoshihiko; Kimura, Syuhei; Wada, Shinichi; Aoyama, Hidefumi; Hayashi, Takafumi

    2016-11-01

    The changes in dose distribution caused by backscatter radiation from a common commercial dental alloy (Au-Ag-Pd dental alloy; DA) were investigated to identify the optimal material and thicknesses of a dental device (DD) for effective prevention of mucositis. To this end, 1 cm(3) of DA was irradiated with a 6-MV X-ray beam (100 MU) in a field size of 10 × 10 cm(2) using a Novalis TX linear accelerator. Ethylene vinyl acetate copolymer, polyolefin elastomer, and polyethylene terephthalate (PET) were selected as DD materials. The depth dose along the central axis was determined with respect to the presence/absence of DA and DDs at thicknesses of 1-10 mm using a parallel-plate ionization chamber. The dose in the absence of DDs showed the lowest value at a distance of 5 mm from the DA surface and gradually increased with distance between the measurement point and the DA surface for distances of ≥5 mm. Except for PET, no significant difference between the DA dose curves for the presence and absence of DDs was observed. In the dose curve, PET showed a slightly higher dose for DA with DD than for DA without DD for thicknesses of ≥4 mm. The findings herein suggest that the optimal DD material for preventing local dose enhancement of the mucosa caused by DA backscatter radiation should have a relatively low atomic number and physical density and that optimal DD thickness should be chosen considering backscatter radiation and percentage depth dose.

  12. TH-C-12A-10: Surface Dose Enhancement Using Novel Hybrid Electron and Photon Low-Z Therapy Beams: Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C; Parsons, D [Dept of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia (Canada); Robar, J; Kelly, R [Dept of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia (Canada); Dept of Radiation Oncology, Dalhousie University, Halifax, Nova Scotia (Canada); Nova Scotia Cancer Centre, Halifax, NS (Canada)

    2014-06-15

    Purpose: The introduction of the TrueBeam linac platform provides access to an in-air target assembly making it possible to apply novel treatments using multiple target designs. One such novel treatment uses multiple low-Z targets to enhance surface dose replacing the use of synthetic tissue equivalent material (bolus). This treatment technique will decrease the common dosimetric and set up errors prevalent in using physical treatment accessories like bolus. The groundwork for a novel treatment beam used to enhance surface dose to within 80-100% of the dose at dmax by utilizing low-Z (Carbon) targets of various percent CSDA range thickness operated at 2.5–4 MeV used in conjunction with a clinical 6 MV beam is presented herein. Methods: A standard Monte Carlo model of a Varian Clinac accelerator was developed to manufacturers specifications. Simulations were performed using Be, C, AL, and C, as potential low-Z targets, placed in the secondary target position. The results determined C to be the target material of choice. Simulations of 15, 30 and 60% CSDA range C beams were propagated through slab phantoms. The resulting PDDs were weighted and combined with a standard 6 MV treatment beam. Versions of the experimental targets were installed into a 2100C Clinac and the models were validated. Results: Carbon was shown to be the low-Z material of choice for this project. Using combinations of 15, 30, 60% CSDA beams operated at 2.5 and 4 MeV in combination with a standard 6 MV treatment beam the surface dose was shown to be enhanced to within 80–100% the dose at dmax. Conclusion: The modeled low-Z beams were successfully validated using machined versions of the targets. Water phantom measurements and slab phantom simulations show excellent correlation. Patient simulations are now underway to compare the use of bolus with the proposed novel beams. NSERC.

  13. High-Dose Estradiol-Replacement Therapy Enhances the Renal Vascular Response to Angiotensin II via an AT2-Receptor Dependent Mechanism

    Directory of Open Access Journals (Sweden)

    Tahereh Safari

    2015-01-01

    Full Text Available Physiological levels of estrogen appear to enhance angiotensin type 2 receptor- (AT2R- mediated vasodilatation. However, the effects of supraphysiological levels of estrogen, analogous to those achieved with high-dose estrogen replacement therapy in postmenopausal women, remain unknown. Therefore, we pretreated ovariectomized rats with a relatively high dose of estrogen (0.5 mg/kg/week for two weeks. Subsequently, renal hemodynamic responses to intravenous angiotensin II (Ang II, 30–300 ng/kg/min were tested under anesthesia, while renal perfusion pressure was held constant. The role of AT2R was examined by pretreating groups of rats with PD123319 or its vehicle. Renal blood flow (RBF decreased in a dose-related manner in response to Ang II. Responses to Ang II were enhanced by pretreatment with estradiol. For example, at 300 ng kg−1 min−1, Ang II reduced RBF by 45.7±1.9% in estradiol-treated rats but only by 27.3±5.1% in vehicle-treated rats. Pretreatment with PD123319 blunted the response of RBF to Ang II in estradiol-treated rats, so that reductions in RBF were similar to those in rats not treated with estradiol. We conclude that supraphysiological levels of estrogen promote AT2R-mediated renal vasoconstriction. This mechanism could potentially contribute to the increased risk of cardiovascular disease associated with hormone replacement therapy using high-dose estrogen.

  14. Low-dose radiation enhances susceptibility to cisplatin in resistant ovarian cancer cells via downregulation of ERCC1 and Bcl-2

    Institute of Scientific and Technical Information of China (English)

    Xiaoran Liu; Donghai Liang; Tao Jiang; Qing Dong; Hongsheng Yu 

    2016-01-01

    Objective Ovarian cancer is one of the leading causes of mortality in patients with malignant gyneco-logical tumors. After surgical intervention for ovarian cancer, cisplatin (DDP)-based chemotherapy is the first-line treatment. However, a major chal enge to treating ovarian cancer is the development of chemore-sistance. Thus, the first aim of this study was to determine whether low-dose radiation could enhance the susceptibility of resistant ovarian cancer cel s to DDP. The second aim was to provide new strategies for treating DDP-resistant ovarian cancer by examining its mechanism. Methods A cel counting kit-8 (CCK8) assay was performed to measure cel proliferation. Flow cytometry was utilized to quantify the apoptosis of DDP-resistant ovarian cancer cel s (SKOV3/DDP) using Annexin V and propidium iodide staining. Real-time quantitative (qPCR) was used to analyze the messenger RNA (mRNA) expression levels of excision repair cross complementing-group 1 (ERCC1) and B-cel lymphoma 2 (Bcl-2) in SKOV3/DDP. Results The IC50 values of the control, conventional-dose, and low-dose groups were 9.367 ± 0.16, 9.289 ± 0.16, and 3.847 ± 0.15, respectively (P Conclusion Low-dose radiation enhanced the sensitivity of resistant ovarian cancer cel s to DDP, pos-sibly by decreasing the DNA repair capacity of tumor cel s and promoting apoptosis.

  15. Effects of orientation of substrate on the enhanced low-dose-rate sensitivity (ELDRS) in NPN transistors

    Institute of Scientific and Technical Information of China (English)

    LU Wu; ZHENG Yu-Zhan; WANG Yi-Yuan; REN Di-Yuan; GUO Qi; WANG Zhi-Kuan; WANG Jian-An

    2011-01-01

    The radiation effects and annealing characteristics of two types of domestic NPN bipolar junction transistors, fabricated with different orientations, were investigated under different dose-rate irradiation. The experimental results show that both types o

  16. Boron Neutron Capture Therapy for Malignant Brain Tumors

    Science.gov (United States)

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

    2016-01-01

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

  17. Boron Neutron Capture Therapy for Malignant Brain Tumors.

    Science.gov (United States)

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

    2016-07-15

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

  18. Raman scattering in heavily boron-doped single-crystal diamond

    Directory of Open Access Journals (Sweden)

    G. Faggio

    2011-09-01

    Full Text Available A series of boron-doped homoepitaxial diamond films grown by Microwave Plasma Enhanced Chemical Vapor Deposition at the University of Rome "Tor Vergata" have been investigated with Raman spectroscopy. As the boron content increases, we observed systematic modifications in the Raman spectra of single-crystal diamonds. A significant change in the lineshape of the first-order Raman peak as well as a wide and structured signal at lower wavenumbers appeared simultaneously in samples grown at higher boron content.

  19. Boron containing poly-(lactide-co-glycolide) (PLGA) scaffolds for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Doğan, Ayşegül; Demirci, Selami [Department of Genetics and Bioengineering, Faculty of Engineering and Architecture, Yeditepe University 34755 Istanbul (Turkey); Bayir, Yasin [Department of Biochemistry, Faculty of Pharmacy, Ataturk University, 25240, Erzurum (Turkey); Halici, Zekai [Department of Pharmacology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Karakus, Emre [Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Ataturk University, 25240, Erzurum (Turkey); Aydin, Ali [Department of Orthopedics and Traumatology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Cadirci, Elif [Department of Pharmacology, Faculty of Pharmacy, Ataturk University, 25240, Erzurum (Turkey); Albayrak, Abdulmecit [Department of Pharmacology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Demirci, Elif [Department of Pathology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Karaman, Adem [Department of Radiology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Ayan, Arif Kursat [Department of Nuclear Medicine, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Gundogdu, Cemal [Department of Pathology, Faculty of Medicine, Ataturk University, 25240, Erzurum (Turkey); Şahin, Fikrettin, E-mail: fsahin@yeditepe.edu.tr [Department of Genetics and Bioengineering, Faculty of Engineering and Architecture, Yeditepe University 34755 Istanbul (Turkey)

    2014-11-01

    Scaffold-based bone defect reconstructions still face many challenges due to their inadequate osteoinductive and osteoconductive properties. Various biocompatible and biodegradable scaffolds, combined with proper cell type and biochemical signal molecules, have attracted significant interest in hard tissue engineering approaches. In the present study, we have evaluated the effects of boron incorporation into poly-(lactide-co-glycolide-acid) (PLGA) scaffolds, with or without rat adipose-derived stem cells (rADSCs), on bone healing in vitro and in vivo. The results revealed that boron containing scaffolds increased in vitro proliferation, attachment and calcium mineralization of rADSCs. In addition, boron containing scaffold application resulted in increased bone regeneration by enhancing osteocalcin, VEGF and collagen type I protein levels in a femur defect model. Bone mineralization density (BMD) and computed tomography (CT) analysis proved that boron incorporated scaffold administration increased the healing rate of bone defects. Transplanting stem cells into boron containing scaffolds was found to further improve bone-related outcomes compared to control groups. Additional studies are highly warranted for the investigation of the mechanical properties of these scaffolds in order to address their potential use in clinics. The study proposes that boron serves as a promising innovative approach in manufacturing scaffold systems for functional bone tissue engineering. - Highlights: • Boron containing PLGA scaffolds were developed for bone tissue engineering. • Boron incorporation increased cell viability and mineralization of stem cells. • Boron containing scaffolds increased bone-related protein expression in vivo. • Implantation of stem cells on boron containing scaffolds improved bone healing.

  20. Preparation of High Purity Amorphous Boron Powder

    Directory of Open Access Journals (Sweden)

    K.V. Tilekar

    2005-10-01

    Full Text Available Amorphous boron powder of high purity (92-94 % with a particle size of l-2 mm is preferred as a fuel for fuel-rich propellants for integrated rocket ramjets and for igniter formulations. Thispaper describes the studies on process optimisation of two processes, ie, oxidative roasting of boron (roasting boron in air and roasting boron with zinc in an inert medium for preparing high purity boron. Experimental studies reveal that roasting boron with zinc at optimised process conditions yields boron of purity more than 93 per cent, whereas oxidative roasting method yields boron of purity - 92 per cent. Oxidative roasting has comparative edge over the other processes owing to its ease of scale-up and simplicity

  1. Low-dose spiruchostatin-B, a potent histone deacetylase inhibitor enhances radiation-induced apoptosis in human lymphoma U937 cells via modulation of redox signaling.

    Science.gov (United States)

    Rehman, Mati Ur; Jawaid, Paras; Zhao, Qing Li; Li, Peng; Narita, Koichi; Katoh, Tadashi; Shimizu, Tadamichi; Kondo, Takashi

    2016-06-01

    Spiruchostatin B (SP-B), is a potent histone deacetylase (HDAC) inhibitor, in addition to HDAC inhibition, the pharmacological effects of SP-B are also attributed to its ability to produce intracellular reactive oxygen species (ROS), particularly H2O2. In this study, we investigated the effects of low dose (non-toxic) SP-B on radiation-induced apoptosis in human lymphoma U937 cells in vitro. The treatment of cells with low-dose SP-B induced the acetylation of histones, however, does not induce apoptosis. Whereas, the combined treatment with SP-B and radiation significantly enhanced the radiation-induced apoptosis, suggesting the potential role of this combined treatment for future radiation therapy. Interestingly, the enhancement of apoptosis was accompanied by significant increased in the ROS generation. Pre-treatment with an antioxidant, N-acetyl-l-cysteine (NAC) significantly inhibited the enhancement of apoptosis induced by combined treatment, indicating that ROS play an essential role. It was also found that SP-B combined with radiation caused the activation of death receptor and intrinsic apoptotic pathways, via modulation of ROS-mediated signaling. Moreover, SP-B also significantly enhanced the radiation-induced apoptosis in other lymphoma cell lines such as Molt-4 and HL-60. Taken together, our findings suggest that the low-dose SP-B enhances radiation-induced apoptosis via modulation of redox signaling because of its ability to serve as an intracellular ROS generating agent, mainly (H2O2 or [Formula: see text]). This study provides further insights into the mechanism of action of SP-B with radiation and demonstrates that SP-B can be used as a future novel sensitizer for radiation therapy.

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

    Science.gov (United States)

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

    2013-02-01

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

  3. Aerolization During Boron Nanoparticle Multi-Component Fuel Group Burning Studies

    Science.gov (United States)

    2014-02-03

    nanoparticle addition (~2.5% weight loading) on aerosol droplet size and velocity distribution fields in the wet , or no flame, condition. Results did suggest...in the presence of boron nanoparticles, suggesting enhanced combustion and increased droplet evaporation in the JP-5 carrier fuel. Additionally, there...no effect of boron nanoparticle addition (~ 2.5 % weight loading) on aerosol droplet size and velocity distribution fields in the wet , or no flame

  4. Reduction of CCR5 with low-dose rapamycin enhances the antiviral activity of vicriviroc against both sensitive and drug-resistant HIV-1.

    Science.gov (United States)

    Heredia, Alonso; Latinovic, Olga; Gallo, Robert C; Melikyan, Gregory; Reitz, Marv; Le, Nhut; Redfield, Robert R

    2008-12-23

    Vicriviroc (VCV) is a chemokine (C-C motif) receptor 5 (CCR5) antagonist with potent anti-HIV activity that currently is being evaluated in phase III clinical trials. In the present study, donor CCR5 density (CCR5 receptors/CD4 lymphocytes) inversely correlated with VCV antiviral activity (Spearman's correlation test; r = 0.746, P = 0.0034). Low doses of the transplant drug rapamycin (RAPA) reduced CCR5 density and enhanced VCV antiviral activity. In drug interaction studies, the RAPA/VCV combination had considerable antiviral synergy (combination indexes of 0.1-0.04) in both multicycle and single-cycle infection of lymphocytes. The synergy between RAPA and VCV translated into dose reduction indexes of 8- to 41-fold reductions for RAPA and 19- to 658-fold reductions for VCV. RAPA enhanced VCV antiviral activity against both B and non-B clade isolates, potently suppressing clade G viruses with reported reduced sensitivities to VCV and to the licensed CCR5 antagonist maraviroc. Importantly, RAPA reduction of CCR5 density in lymphocytes sensitized VCV-resistant strains to VCV, inhibiting virus production by approximately 90%. We further demonstrated the role of CCR5 density on VCV activity against resistant virus in donor lymphocytes and in cell lines expressing varying CCR5 densities. Together, these results suggest that low doses of RAPA may increase the durability of VCV-containing regimens in patients by enhancing VCV viral suppression, by allowing the use of lower doses of VCV with reduced potential for toxicity, and by controlling emerging VCV-resistant variants.

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

    OpenAIRE

    He, Chaoyu; Zhong, Jianxin

    2013-01-01

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

  6. Synthesis of a boron modified phenolic resin

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2010-08-01

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

  7. Enhanced production of reactive oxygen species by gadolinium oxide nanoparticles under core-inner-shell excitation by proton or monochromatic X-ray irradiation: implication of the contribution from the interatomic de-excitation-mediated nanoradiator effect to dose enhancement.

    Science.gov (United States)

    Seo, Seung-Jun; Han, Sung-Mi; Cho, Jae-Hoon; Hyodo, Kazuyuki; Zaboronok, Alexander; You, He; Peach, Ken; Hill, Mark A; Kim, Jong-Ki

    2015-11-01

    Core-inner-valence ionization of high-Z nanoparticle atomic clusters can de-excite electrons through various interatomic de-excitation processes, thereby leading to the ionization of both directly exposed atoms and adjacent neutral atoms within the nanoparticles, and to an enhancement in photon-electron emission, which is termed the nanoradiator effect. To investigate the nanoradiator-mediated dose enhancement in the radio-sensitizing of high-Z nanoparticles, the production of reactive oxygen species (ROS) was measured in a gadolinium oxide nanoparticle (Gd-oxide NP) solution under core-inner-valence excitation of Gd with either 50 keV monochromatic synchrotron X-rays or 45 MeV protons. This measurement was compared with either a radiation-only control or a gadolinium-chelate magnetic resonance imaging contrast agent solution containing equal amounts of gadolinium as the separate atomic species in which Gd-Gd interatomic de-excitations are absent. Ionization excitations followed by ROS measurements were performed on nanoparticle-loaded cells or aqueous solutions. Both photoexcitation and proton impact produced a dose-dependent enhancement in the production of ROS by a range of factors from 1.6 to 1.94 compared with the radiation-only control. Enhanced production of ROS, by a factor of 1.83, was observed from Gd-oxide NP atomic clusters compared with the Gd-chelate molecule, with a Gd concentration of 48 μg/mL in the core-level photon excitation, or by a factor of 1.82 under a Gd concentration of 12 μg/mL for the proton impact at 10 Gy (p < 0.02). The enhanced production of ROS in the irradiated nanoparticles suggests the potential for additional therapeutic dose enhancements in radiation treatment via the potent Gd-Gd interatomic de-excitation-driven nanoradiator effect.

  8. Efeito de déficit hídrico transiente e doses crescentes de boro sobre a fertilidade de gemas de videira cv. Itália Effects of transient water stress and increasing doses of boron on the bud fertility in grapevines cv. Itália

    Directory of Open Access Journals (Sweden)

    Jorbas Sampaio de Melo

    2011-06-01

    Full Text Available O objetivo deste trabalho foi verificar o efeito de diferentes tensões de água no solo e diferentes concentrações de boro, na fertilidade de gemas de videira cv. Itália, manejada sob o sistema de poda mista. O experimento foi conduzido em pomar comercial, no município de Petrolina-PE. O delineamento experimental utilizado foi o de blocos ao acaso, em esquema fatorial 3x3: três tensões indicativas para a recarga hídrica por irrigação (-30 kPa, -50 kPa e -70 kPa e três concentrações de boro (3%, 6% e 9%, com três repetições e duas plantas por parcela. A testemunha não recebeu aplicações com boro e o solo foi mantido com umidade na capacidade de campo (-10 kPa. As variáveis analisadas foram fertilidade de gemas, índice relativo de clorofila (IRC e área foliar. Os dados foram interpretados por meio de análise de variância e regressão, e os modelos escolhidos com base na significância do coeficiente de regressão (R² > 0,70. Verificou-se que a fertilidade de gemas mostrou efeito linear negativo em função do aumento da tensão de água no solo, diminuindo de 31,88% (-30 kPa, para 23,66% (-70 kPa. Contudo, a fertilidade de gemas nas videiras submetidas a uma restrição hídrica de -30 kPa foi superior à tensão de -10 kPa; o boro a 3% propiciou a maior taxa de fertilidade de gemas em comparação aos demais tratamentos com boro; a restrição hídrica no solo a -30 kPa ocasionou economia no volume de água aplicada da ordem de 35,4% em comparação ao manejo com -10 kPa; o índice relativo de clorofila aumentou linearmente com o acréscimo das tensões de água no solo e houve maior expansão da área foliar em plantas submetidas ao manejo da irrigação na capacidade de campo.The present paper had the purpose to ascertain the effects of different soil water tensions and different concentrations of boron on the bud fertility in grapevines cv. Italia, grown under a mixed system of pruning. The experiment was conducted in

  9. Boron doping a semiconductor particle

    Science.gov (United States)

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

    1998-06-09

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

  10. The effects of increased dose of exercise-based therapies to enhance motor recovery after stroke: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Tallis Raymond C

    2010-10-01

    Full Text Available Abstract Background Exercise-based therapy is known to enhance motor recovery after stroke but the most appropriate amount, i.e. the dose, of therapy is unknown. To determine the strength of current evidence for provision of a higher dose of the same types of exercise-based therapy to enhance motor recovery after stroke. Methods An electronic search of: MEDLINE, EMBASE, CINHAL, AMED, and CENTRAL was undertaken. Two independent reviewers selected studies using predetermined inclusion criteria: randomised or quasi randomised controlled trials with or without blinding of assessors; adults, 18+ years, with a clinical diagnosis of stroke; experimental and control group interventions identical except for dose; exercise-based interventions investigated; and outcome measures of motor impairment, movement control or functional activity. Two reviewers independently extracted outcome and follow-up data. Effect sizes and 95% confidence intervals were interpreted with reference to risk of bias in included studies. Results 9 papers reporting 7 studies were included. Only 3 of the 7 included studies had all design elements assessed as low risk of bias. Intensity of the control intervention ranged from a mean of 9 to 28 hours over a maximum of 20 weeks. Experimental groups received between 14 and 92 hours of therapy over a maximum of 20 weeks. The included studies were heterogeneous with respect to types of therapy, outcome measures and time-points for outcome and follow-up. Consequently, most effect sizes relate to one study only. Single study effect sizes suggest a trend for better recovery with increased dose at the end of therapy but this trend was less evident at follow-up Meta-analysis was possible at outcome for: hand-grip strength, -10.1 [-19.1,-1.2] (2 studies, 97 participants; Action Research Arm Test (ARAT, 0.1 [-5.7,6.0] (3 studies, 126 participants; and comfortable walking speed, 0.3 [0.1,0.5] (2 studies, 58 participants. At follow-up, between 12

  11. Biodegradation of an oil-hydrocarbon contaminated soil, enhanced by surfactants: Effect of the type and dose of surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Torres, L. G.; Galindo, C.; Rojas, N.; Iturbe, R.

    2009-07-01

    The aim of this work was to study the effect of different parameters, such as surfactant type an dose, soil initial hydrocarbons concentration, and soil granulometry, over the total petroleum hydrocarbons TPH degradation, as well as over the microbial count (as colony formation units CFU/g soil) along the process. (Author)

  12. Cerebral computed tomography angiography using a 70 kVp protocol: improved vascular enhancement with a reduced volume of contrast medium and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Eun-Suk; Chung, Tae-Sub; Baek, Jang Hun; Suh, Sang Hyun [Gangnam Severance Hospital, Department of Radiology, Yonsei University College of Medicine, Gangnam-gu, Seoul (Korea, Republic of); Ahn, Sung Jun [Severance Hospital, Department of Radiology, Yonsei University College of Medicine, Seodaemun-gu, Seoul (Korea, Republic of); Chong, KyoungHoon [Siemens Healthcare Korea, Seodaemun-gu, Seoul (Korea, Republic of)

    2015-05-01

    To determine the feasibility of using a 70-kVp protocol compared with a 120-kVp protocol for cerebral CT angiography. An additional target was to investigate a possible reduction in the volume of contrast medium (CM) using the 70-kVp protocol. Attenuation value and CNR for iodine were determined at various tube voltage settings using a phantom. Sixty-nine volunteers were randomly assigned to one of three protocols: group A (120-kVp and CM 64 mL), group B (70-kVp and CM 64 mL), or group C (70-kVp and CM 40 mL). The attenuation value, SNR, and CNR of cerebral arteries, subjective image quality, and radiation dose were compared among the groups. The vascular attenuation, SNR, and CNR of group B were significantly higher than those of group A. Group C had a significantly higher vascular attenuation than group A. Groups B and C were significantly better than group A with respect to subjective image quality. An effective dose of 70-kVp was 10 % lower than that of 120-kVp. Using 70-kVp improved arterial enhancement, SNR, and CNR, and provided better subjective image quality, using a 10 % lower effective dose. Furthermore, the 70-kVp protocol may both reduce volume of CM by 37.5 % and improve arterial enhancement. (orig.)

  13. Thermal conductivity of boron carbides

    Science.gov (United States)

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

    1985-01-01

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

  14. An overview of male reproductive studies of boron with an emphasis on studies of highly exposed Chinese workers

    DEFF Research Database (Denmark)

    Scialli, Anthony R; Bonde, Jens Peter; Brüske-Hohlfeld, Irene;

    2010-01-01

    Boron treatment of rats, mice, and dogs has been associated with testicular toxicity, characterized by inhibited spermiation at lower dose levels and a reduction in epididymal sperm count at higher dose levels. The no-adverse-effect level for reproductive effects in male rats is 17.5mg B/kg bw....../day. Earlier studies in human workers and populations have not identified adverse effects of boron exposure on fertility, but outcome measures in these studies were relatively insensitive, based mainly on family size and did not include an evaluation of semen end points. A recent study of nearly 1000 men...... working in boron (B) mining or processing in Liaoning province in northeast China has been published in several Chinese and a few English language papers. This study included individual assessment of boron exposure, interview data on reproductive experience and semen analysis. Employed men living...

  15. Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron

    OpenAIRE

    Horitsugi, Genki; Fujibuchi, Toshioh; Yamaguchi, Ichiro; Eto, Akihisa; Iwamoto, Yasuo; Hashimoto, Hiromi; Hamada, Seiki; Obara, Satoshi; Watanabe, Hiroshi; Hatazawa, Jun

    2012-01-01

    The cyclotron at our hospital has a self-shield of boron-containing water. The amount of induced radioactivity in the boron-containing water shield of a compact medical cyclotron has not yet been reported. In this study, we measured the photon and neutron dose rates outside the self-shield during cyclotron operation. We estimated the induced radioactivities of the boron-containing water used for the self-shield and then measured them. We estimated the activation of concrete outside the self-s...

  16. The dual-dose imaging technique: a way to enhance the dynamic range of X-ray detectors

    CERN Document Server

    Matsinos, E; Matsinos, Evangelos; Kaissl, Wolfgang

    2006-01-01

    We describe a method aiming at increasing the dynamic range of X-ray detectors. Two X-ray exposures of an object are acquired at different dose levels and constitute the only input data. The values of the parameters which are needed to process these images are determined from information contained in the images themselves; the values of two parameters are extracted from the input data. The two input images are finally merged in such a way as to create one image containing useful information in all its entirety. This selective use of parts of each image allows both the contour of the irradiated object to be visible and the high-attenuation areas to retain their image quality corresponding to the information contained in the high-dose image. The benefits of the method are demonstrated with an example involving a head phantom.

  17. Long-term exposures to low doses of cobalt nanoparticles induce cell transformation enhanced by oxidative damage.

    Science.gov (United States)

    Annangi, Balasubramanyam; Bach, Jordi; Vales, Gerard; Rubio, Laura; Marcos, Ricard; Hernández, Alba

    2015-03-01

    A weak aspect of the in vitro studies devoted to get information on the toxic, genotoxic and carcinogenic properties of nanomaterials is that they are usually conducted under acute-exposure and high-dose conditions. This makes difficult to extrapolate the results to human beings. To overcome this point, we have evaluated the cell transforming ability of cobalt nanoparticles (CoNPs) after long-term exposures (12 weeks) to sub-toxic doses (0.05 and 0.1 µg/mL). To get further information on whether CoNPs-induced oxidative DNA damage is relevant for CoNPs carcinogenesis, the cell lines selected for the study were the wild-type mouse embryonic fibroblast (MEF Ogg1(+/+)) and its isogenic Ogg1 knockout partner (MEF Ogg1(-)(/)(-)), unable to properly eliminate the 8-OH-dG lesions from DNA. Our initial short-term exposure experiments demonstrate that low doses of CoNPs are able to induce reactive oxygen species (ROS) and that MEF Ogg1(-)(/)(-) cells are more sensitive to CoNPs-induced acute toxicity and oxidative DNA damage. On the other hand, long-term exposures of MEF cells to sub-toxic doses of CoNPs were able to induce cell transformation, as indicated by the observed morphological cell changes, significant increases in the secretion of metalloproteinases (MMPs) and anchorage-independent cell growth ability, all cancer-like phenotypic hallmarks. Interestingly, such changes were significantly dependent on the cell line used, the Ogg1(-)(/)(-) cells being particularly sensitive. Altogether, the data presented here confirms the potential carcinogenic risk of CoNPs and points out the relevance of ROS and Ogg1 genetic background on CoNPs-associated effects.

  18. Enhancements to commissioning techniques and quality assurance of brachytherapy treatment planning systems that use model-based dose calculation algorithms.

    Science.gov (United States)

    Rivard, Mark J; Beaulieu, Luc; Mourtada, Firas

    2010-06-01

    The current standard for brachytherapy dose calculations is based on the AAPM TG-43 formalism. Simplifications used in the TG-43 formalism have been challenged by many publications over the past decade. With the continuous increase in computing power, approaches based on fundamental physics processes or physics models such as the linear-Boltzmann transport equation are now applicable in a clinical setting. Thus, model-based dose calculation algorithms (MBDCAs) have been introduced to address TG-43 limitations for brachytherapy. The MBDCA approach results in a paradigm shift, which will require a concerted effort to integrate them properly into the radiation therapy community. MBDCA will improve treatment planning relative to the implementation of the traditional TG-43 formalism by accounting for individualized, patient-specific radiation scatter conditions, and the radiological effect of material heterogeneities differing from water. A snapshot of the current status of MBDCA and AAPM Task Group reports related to the subject of QA recommendations for brachytherapy treatment planning is presented. Some simplified Monte Carlo simulation results are also presented to delineate the effects MBDCA are called to account for and facilitate the discussion on suggestions for (i) new QA standards to augment current societal recommendations, (ii) consideration of dose specification such as dose to medium in medium, collisional kerma to medium in medium, or collisional kerma to water in medium, and (iii) infrastructure needed to uniformly introduce these new algorithms. Suggestions in this Vision 20/20 article may serve as a basis for developing future standards to be recommended by professional societies such as the AAPM, ESTRO, and ABS toward providing consistent clinical implementation throughout the brachytherapy community and rigorous quality management of MBDCA-based treatment planning systems.

  19. Dose-dependent effect of donepezil administration on long-term enhancement of visually evoked potentials and cholinergic receptor overexpression in rat visual cortex.

    Science.gov (United States)

    Chamoun, Mira; Groleau, Marianne; Bhat, Menakshi; Vaucher, Elvire

    2016-09-01

    Stimulation of the cholinergic system tightly coupled with periods of visual stimulation boosts the processing of specific visual stimuli via muscarinic and nicotinic receptors in terms of intensity, priority and long-term effect. However, it is not known whether more diffuse pharmacological stimulation with donepezil, a cholinesterase inhibitor, is an efficient tool for enhancing visual processing and perception. The goal of the present study was to potentiate cholinergic transmission with donepezil treatment (0.5 and 1mg/kg) during a 2-week visual training to examine the effect on visually evoked potentials and to profile the expression of cholinergic receptor subtypes. The visual training was performed daily, 10min a day, for 2weeks. One week after the last training session, visual evoked potentials were recorded, or the mRNA expression level of muscarinic (M1-5) and nicotinic (α/β) receptors subunits was determined by quantitative RT-PCR. The visual stimulation coupled with any of the two doses of donepezil produced significant amplitude enhancement of cortical evoked potentials compared to pre-training values. The enhancement induced by the 1mg/kg dose of donepezil was spread to neighboring spatial frequencies, suggesting a better sensitivity near the visual detection threshold. The M3, M4, M5 and α7 receptors mRNA were upregulated in the visual cortex for the higher dose of donepezil but not the lower one, and the receptors expression was stable in the somatosensory (non-visual control) cortex. Therefore, higher levels of acetylcholine within the cortex sustain the increased intensity of the cortical response and trigger the upregulation of cholinergic receptors.

  20. Advanced microstructure of boron carbide.

    Science.gov (United States)

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

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

  1. Reduction of CCR5 with low-dose rapamycin enhances the antiviral activity of vicriviroc against both sensitive and drug-resistant HIV-1

    OpenAIRE

    2008-01-01

    Vicriviroc (VCV) is a chemokine (C-C motif) receptor 5 (CCR5) antagonist with potent anti-HIV activity that currently is being evaluated in phase III clinical trials. In the present study, donor CCR5 density (CCR5 receptors/CD4 lymphocytes) inversely correlated with VCV antiviral activity (Spearman's correlation test; r = 0.746, P = 0.0034). Low doses of the transplant drug rapamycin (RAPA) reduced CCR5 density and enhanced VCV antiviral activity. In drug interaction studies, the RAPA/VCV com...

  2. Rational design of gold nanoparticles functionalized with carboranes for application in Boron Neutron Capture Therapy.

    Science.gov (United States)

    Ciani, Laura; Bortolussi, Silva; Postuma, Ian; Cansolino, Laura; Ferrari, Cinzia; Panza, Luigi; Altieri, Saverio; Ristori, Sandra

    2013-12-31

    In this paper we propose a bottom-up approach to obtain new boron carriers built with ortho-carborane functionalized gold nanoparticles (GNPs) for applications in Boron Neutron Capture Therapy. The interaction between carboranes and the gold surface was assured by one or two SH-groups directly linked to the boron atoms of the B10C2 cage. This allowed obtaining stable, nontoxic systems, though optimal biological performance was hampered by low solubility in aqueous media. To improve cell uptake, the hydrophilic character of carborane functionalized GNPs was enhanced by further coverage with an appropriately tailored diblock copolymer (PEO-b-PCL). This polymer also contained pendant carboranes to provide anchoring to the pre-functionalized GNPs. In vitro tests, carried out on osteosarcoma cells, showed that the final vectors possessed excellent biocompatibility joint to the capacity of concentrating boron atoms in the target, which is encouraging evidenced to pursue applications in vivo.

  3. Enhanced binding capacity of boronate affinity adsorbent via surface modification of silica by combination of atom transfer radical polymerization and chain-end functionalization for high-efficiency enrichment of cis-diol molecules.

    Science.gov (United States)

    Wang, Wei; He, Maofang; Wang, Chaozhan; Wei, Yinmao

    2015-07-30

    Boronate affinity materials have been widely used for specific separation and preconcentration of cis-diol molecules, but most do not have sufficient capacity due to limited binding sites on the material surface. In this work, we prepared a phenylboronic acid-functionalized adsorbent with a high binding capacity via the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and chain-end functionalization. With this method, the terminal chlorides of the polymer chains were used fully, and the proposed adsorbent contains dense boronic acid polymers chain with boronic acid on the chain end. Consequently, the proposed adsorbent possesses excellent selectivity and a high binding capacity of 513.6 μmol g(-1) for catechol and 736.8 μmol g(-1) for fructose, which are much higher than those of other reported adsorbents. The dispersed solid-phase extraction (dSPE) based on the prepared adsorbent was used for extraction of three cis-diol drugs (i.e., epinephrine, isoprenaline and caffeic acid isopropyl ester) from plasma; the eluates were analyzed by HPLC-UV. The reduced amount of adsorbent (i.e., 2.0 mg) could still eliminate interferences efficiently and yielded a recovery range of 85.6-101.1% with relative standard deviations ranging from 2.5 to 9.7% (n = 5). The results indicated that the proposed strategy could serve as a promising alternative to increase the density of surface functional groups on the adsorbent; thus, the prepared adsorbent has the potential to effectively enrich cis-diol substances in real samples.

  4. 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.

  5. Dose enhancement by synchrotron radiation and heavy atoms for the treatment of gliomas; Renforcement de la dose par rayonnement synchrotron et atomes lourds dans le cadre du traitement des gliomes

    Energy Technology Data Exchange (ETDEWEB)

    Bobyk, L.

    2010-11-15

    High grade gliomas are brain tumors of bad prognosis. The standard therapeutic treatment combines surgery, radiotherapy and sometimes use of temozolomide (chemotherapy agent). Healthy tissues radio-sensitivity is a major limitation for radiotherapy treatment. The stereotactic radiotherapy by synchrotron radiation is an innovative technique which combines a low energy radiation (lower 100 keV) with the presence of heavy atoms in the tumoral zone. Such an approach is used to increase the differential of dose deposited in the tumor compared to surrounding healthy tissues. In this study, several compounds containing heavy atoms such as chemotherapy agents: cisplatin/carbo-platin, a DNA base analog: 5-iodo-2'-deoxyuridine (IUdR) and gold nano-particles were considered. The dose enhancement factor induced by the presence of these compounds located for some of them in the extracellular medium or inside the cells for others, was determined using in vitro studies. Thereafter, in vivo studies on rats bearing gliomas, were performed to study the toxicity, the kinetic of distribution and the localization of these compounds together with their potential efficacy of treatment combining intracerebral injection with low energy radiation. (author)

  6. Enhanced binding capacity of boronate affinity adsorbent via surface modification of silica by combination of atom transfer radical polymerization and chain-end functionalization for high-efficiency enrichment of cis-diol molecules

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; He, Maofang; Wang, Chaozhan; Wei, Yinmao, E-mail: ymwei@nwu.edu.cn

    2015-07-30

    Boronate affinity materials have been widely used for specific separation and preconcentration of cis-diol molecules, but most do not have sufficient capacity due to limited binding sites on the material surface. In this work, we prepared a phenylboronic acid-functionalized adsorbent with a high binding capacity via the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and chain-end functionalization. With this method, the terminal chlorides of the polymer chains were used fully, and the proposed adsorbent contains dense boronic acid polymers chain with boronic acid on the chain end. Consequently, the proposed adsorbent possesses excellent selectivity and a high binding capacity of 513.6 μmol g{sup −1} for catechol and 736.8 μmol g{sup −1} for fructose, which are much higher than those of other reported adsorbents. The dispersed solid-phase extraction (dSPE) based on the prepared adsorbent was used for extraction of three cis-diol drugs (i.e., epinephrine, isoprenaline and caffeic acid isopropyl ester) from plasma; the eluates were analyzed by HPLC-UV. The reduced amount of adsorbent (i.e., 2.0 mg) could still eliminate interferences efficiently and yielded a recovery range of 85.6–101.1% with relative standard deviations ranging from 2.5 to 9.7% (n = 5). The results indicated that the proposed strategy could serve as a promising alternative to increase the density of surface functional groups on the adsorbent; thus, the prepared adsorbent has the potential to effectively enrich cis-diol substances in real samples. - Highlights: • Boronate adsorbent is prepared via ATRP and chain-end functionalization. • The adsorbent has quite high binding capacity for cis-diols. • Binding capacity is easily manipulated by ATRP condition. • Chain-end functionalization can improve binding capacity significantly. • Reduced adsorbent is consumed in dispersed solid-phase extraction of cis-diols.

  7. Enhancement of transformation rates in higher plants by low-dose irradiation: Are DNA repair systems involved in the incorporation of exogenous DNA into the plant genome?

    Science.gov (United States)

    Köhler, F; Cardon, G; Pöhlman, M; Gill, R; Schieder, O

    1989-02-01

    Irradiation (X-ray; 5-15 Gy) of protoplasts treated with plasmid-DNA and PEG yielded higher transformation rates in comparison to non-irradiated protoplasts transformed by the same method. This could be demonstrated for four plant species. The irradiation doses used did not affect the total number of colonies regenerated without selection pressure, but resulted in 3-6-fold enhancement of hygromycin- or kanamycin-resistant colonies. Plant regeneration frequencies of transformed colonies derived from irradiated and non-irradiated protoplasts were similar in tobacco as well as in Petunia. Higher integration rates of foreign DNA as a consequence of an increased recombination machinery in irradiated cells may be responsible for the enhancement of the number of stably transformed colonies.

  8. First-principles study of palladium atom adsorption on the boron- or nitrogen-doped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Guoxiang [College of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062, Shaanxi (China); School of Science, Xi' an Shiyou University, Xi' an 710065, Shaanxi (China); Zhang Jianmin, E-mail: jianm_zhang@yahoo.co [College of Physics and Information Technology, Shaanxi Normal University, Xi' an 710062, Shaanxi (China); Wang Doudou [Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xi' an 710077, Shaanxi (China); Xu Kewei [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2009-11-15

    We have performed first-principles calculation to investigate the adsorption of a single palladium atom on the surface of the pristine and boron- or nitrogen-doped carbon nanotubes (CNTs). The results show that for the adsorption of a single palladium atom on the pristine CNT surface, the most stable site is Bridge1 site above the axial carbon-carbon bond. Either boron- or nitrogen-doped CNTs can assist palladium surface adsorption, but the detailed mechanisms are different. The enhanced palladium adsorption on boron-doped CNT is attributed to the palladium d orbital strongly hybridized with both boron p orbital and carbon p orbital. The enhancement in palladium adsorption on nitrogen-doped CNT results from activating the nitrogen-neighboring carbon atoms due to the large electron affinity of nitrogen. Furthermore, the axial bond is preferred over the zigzag bond for a palladium atom adsorbed on the surface of all three types of CNTs. The most energetically favorable site for a palladium atom adsorbed on three types of CNTs is above the axial boron-carbon bond in boron-doped CNT. The enhancement in palladium adsorption is more significant for the boron-doped CNT than it is for nitrogen-doped CNT with a similar configuration. So we conclude that accordingly, the preferred adsorption site is determined by the competition between the electron affinity of doped and adsorbed atoms and preferred degree of the axial bond over the zigzag bond.

  9. Epithermal neutron beam adoption for liver cancer treatment by boron and gadolinium neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Tetsuo [Musashi Inst. of Tech., Kawasaki, Kanagawa (Japan). Atomic Energy Research Lab

    2001-06-01

    Comparative evaluation was made on depth-dose distribution in boron neutron capture therapy (B-NCT) and gadolinium one (Gd-NCT) for the treatments of liver cancers. At present, epithermal neutron beam is expected to be applicable to the treatment of deep and widespread tumors. ICRU computational model of ADAM and EVA was used as a liver phantom loading a tumor at depth of 6 cm in its central region. Epithermal neutron beam of Musashi reactor was used as the primary neutron beam for the depth-dose calculation. Calculation was conducted using the three-dimensional continuous-energy Monte Carlo code MCNP4A. The doses observed in both NCTs were bumped over the tumor region but the dose for Gd-NCT was not so tumor-specific compared with that for BNCT because radiation in Gd-NCT was due to {gamma}-ray. The mean physical dose was 4 Gy/h for boron 30 ppm and 5 Gy/h for Gd 1000 ppm when exposed to an epithermal neutron flux of 5x10{sup 8} n/cm{sup -2}/sec and the dose ratio of tumor-to normal tissue was 2.7 for boron and 2.5 for Gd. The lethal dose of 50 Gy for the liver can be accomplished under conditions where the dose has not reached 25 Gy, the tolerance dose of the normal tissue. This seems very encouraging and indicating that both B-NCT and Gd-NCT are applicable for the treatment for liver cancer. However, if normal tissue contain 1/4 of the tumor concentration of boron or Gd, the BNCT would still possible when considering a large RBE value for {sup 10}B(n, {alpha}) reaction but the Gd-NCT would impossible for deep liver treatment. (M.N.)

  10. Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-04-07

    amphiphilic unimolecular nanoparticles presenting several advantages: tunable size through functionalization and branching, spherical shape due to the icosahedral B122 core, promising water solubility resulting from degradation of all pendant closo-carborane groups to their hydrophilic nido anion substituents, and efficient boron delivery owing to the presence of 120 boron atoms which gives rise to a boron content as high as 40% by weight. Keeping the new objective in mind, we have focused on the design, synthesis and evaluation of new and very boron-rich closomer species. Additionally, progress has also been made toward the evaluation of a newly synthesized boron-rich lipid as a substitute for DSPC in bilayer construction, and the boron content of the resulting liposomes has been greatly enhanced. Related research involving the synthesis and self-assembly of carborane-containing amphiphiles has been systematically studied. Combined hydrophobic and hydrophilic properties of the single-chain amphiphiles allow their spontaneous self-assembly to form rods under a variety of variable conditions, such as concentration in the bilayer, carborane cage structure, chain-length, counterion identity, solvents, methods of preparation, and the ionic charge. On the other hand, the number of attached chains affects the self-assembly process. Particles having totally different shapes have been observed for dual-chain amphiphiles.

  11. IRIS TOXICOLOGICAL REVIEW AND SUMMARY DOCUMENTS FOR BORON AND COMPOUNDS (THIRD EXTERNAL REVIEW DRAFT 2002)

    Science.gov (United States)

    The U. S. EPA has conducted a peer review of the scientific basis supporting the health hazard and dose response assessment for Boron that will appear on the Agency's online data base, the Integrated Risk Information System (IRIS). Peer Review is meant to ensure that science is u...

  12. Release of native and amended boron from arid zone soils after varying incubation times

    Science.gov (United States)

    In this study we evaluated the boron (B) release from soils containing elevated native B and examined the extent to which incubation time affected B release. Five soils varying in initial pH and clay content were selected for the study. The soils were spiked with five varying doses of B as H3BO3 (...

  13. An Exploration of Neutron Detection in Semiconducting Boron Carbide

    Science.gov (United States)

    Hong, Nina

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

  14. Enhancement of Dose Response and Nuclear Magnetic Resonance Image of PAGAT Polymer Gel Dosimeter by Adding Silver Nanoparticles

    Science.gov (United States)

    Sabbaghizadeh, Rahim; Shamsudin, Roslinda; Deyhimihaghighi, Najmeh; Sedghi, Arman

    2017-01-01

    In the present study, the normoxic polyacrylamide gelatin and tetrakis hydroxy methyl phosphoniun chloride (PAGAT) polymer gel dosimeters were synthesized with and without the presence of silver (Ag) nanoparticles. The amount of Ag nanoparticles varied from 1 to 3 ml with concentration 3.14 g/l, thus forming two types of PAGAT polymer gel dosimeters before irradiating them with 6 to 25 Gy produced by 1.25-MeV 60Co gamma rays. In this range, the predominant gamma ray interaction with matter is by Compton scattering effect, as the photoelectric absorption effect diminishes. MRI was employed when evaluating the polymerization of the dosimeters and the gray scale of the MRI film was determined via an optical densitometer. Subsequent analyses of optical densities revealed that the extent of polymerization increased with the increase in the absorbed dose, while the increase of penetration depth within the dosimeters has a reverse effect. Moreover, a significant increase in the optical density-dose response (11.82%) was noted for dosimeters containing 2 ml Ag nanoparticles. PMID:28060829

  15. PREVENTIVE EFFECT OF BORON ON DAMAGE TO CARTILAGE OF RATS WITH INTAKE EXCESSIVE FLUORIDE

    Institute of Scientific and Technical Information of China (English)

    Xu Peng; Guo Xiong; Cao Hui; Kang Longli; Du Xiaoyang; Zhang Zengtie; Geng Dong

    2005-01-01

    Objective To investigate and analyze the preventive effect of boron on the cartilage damage in rats with intake excessive fluoride. Methods Fifty-ix Sprague-Dawley rats were divided into the control group (C, intake distilled water), the excessive fluoride dose group (EF, intake distilled water with 100 ppm F-) and the boron prevention group (P, intake distilled water with 100 ppm F- as well as the supplemental boron dietary). 3 to 5 months later, fluorine contents in serum, RNA contents in costal cartilage were assayed. The morphological changes in tibia growth plate cartilage (GPC) in rats were observed. Results Although exposed to the same dose of fluoride, the fluorine contents in serum in rats of P group decreased notably compared with those of EF group, the damage of tibia GPC under optical and electron microscope lessened significantly, and RNA contents in costal cartilage increased obviously in the 3rd month. Conclusion Boron added could decrease the fluorine level in the body and relieve the toxic symptom of excess fluoride, and thus boron has a preventive effect on skeletal fluorosis.

  16. Long-time treatment by low-dose N-acetyl-L-cysteine enhances proinflammatory cytokine expressions in LPS-stimulated macrophages.

    Directory of Open Access Journals (Sweden)

    Tomokazu Ohnishi

    Full Text Available N-acetyl-L-cysteine is known to act as a reactive oxygen species scavenger and used in clinical applications. Previous reports have shown that high-dose N-acetyl-L-cysteine treatment inhibits the expression of proinflammatory cytokines in activated macrophages. Here, we have found that long-time N-acetyl-L-cysteine treatment at low-concentration increases phosphorylation of extracellular signal-regulated kinase 1/2 and AKT, which are essential for the induction of proinflammatory cytokines including interleukin 1β and interleukin 6 in lipopolysaccharide-stimulated RAW264.7 cells. Furthermore, long-time N-acetyl-L-cysteine treatment decreases expressions of protein phosphatases, catalytic subunit of protein phosphatase-2A and dual specificity phosphatase 1. On the other hand, we have found that short-time N-acetyl-L-cysteine treatment at low dose increases p53 expression, which inhibits expressions of proinflammatory cytokines. These observations suggest that long-time low-dose N-acetyl-L-cysteine treatment increases expressions of proinflammatory cytokines through enhancement of kinase phosphorylation.

  17. Comparison of acquisition time and dose for late gadolinium enhancement imaging at 3.0 T in patients with chronic myocardial infarction using Gd-BOPTA

    Energy Technology Data Exchange (ETDEWEB)

    Doltra, A.; Skorin, A.; Gebker, R.; Klein, C.; Fleck, E.; Kelle, S. [German Heart Institute Berlin, Department of Internal Medicine/Cardiology, Berlin (Germany); Hamdan, A. [Tel Aviv University, Heart Center, Chaim Sheba Medical Center, Tel Hashomer, Sackler Faculty of Medicine, Tel Aviv (Israel); Schnackenburg, B. [Philips Healthcare, Clinical Science, Hamburg (Germany); Nagel, E. [King' s College London, Department of Cardiovascular Imaging, London (United Kingdom)

    2014-09-15

    To compare contrast doses and acquisition times for late gadolinium enhancement (LGE) imaging at 3.0 T using gadobenate dimeglumine (Gd-BOPTA) in patients with chronic myocardial infarction. Thirty-four patients with chronic myocardial infarction were randomised to 0.10, 0.15 and 0.20 mmol/kg of Gd-BOPTA. T1-weighted inversion recovery gradient echo sequences were performed at 5, 10, 15 and 20 min post-administration of contrast in a 3.0-T scanner. Scar-to-myocardium contrast-to-noise ratio (CNR), scar-to-blood CNR, scar size and image quality were assessed. Imaging at 5 min was associated with a lower scar-to-blood CNR in comparison to 10, 15 and 20 min at 0.10 mmol/kg, and in comparison to 15 and 20 min at 0.20 mmol/kg. At 0.10-mmol/kg, imaging at 5 min yielded smaller infarct sizes in comparison to 15 and 20 min. Finally, at 0.20-mmol/kg, imaging at 5 min was associated with poorer image quality in comparison to later times. In LGE imaging at 3.0 T, low doses of Gd-BOPTA perform equally well as higher doses. Early acquisition (5 min) is associated with lower infarct sizes and image quality. Studies with sufficient diagnostic quality can be obtained after 10 min using 0.10 mmol/kg Gd-BOPTA. (orig.)

  18. Boron attenuates malathion-induced oxidative stress and acetylcholinesterase inhibition in rats.

    Science.gov (United States)

    Coban, Funda Karabag; Ince, Sinan; Kucukkurt, Ismail; Demirel, Hasan Huseyin; Hazman, Omer

    2015-10-01

    Organophosphorus compounds cause oxidative stress and lead to alterations in antioxidant status in organisms. In this study, the effects of subchronic exposure to malathion and the protective effects of boron (B) were evaluated in 48 Wistar rats, which were divided equally into six groups. For 28 d, the control group received a normal diet and tap water, the corn oil group received a normal diet and 0.5 mL of corn oil by gastric gavage and the malathion group received a normal diet and malathion (100 mg/kg/d) by gastric gavage. During the same period, each of the three other groups received a different dosage of B (5, 10 and 20 mg/kg/d, respectively) and malathion (100 mg/kg/d) by gastric gavage. Malathion administration during the period increased malondialdehyde, nitric oxide and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, as well as markers of liver function, yet decreased acetylcholinesterase, reduced glutathione, superoxide dismutase, and catalase activities in blood, liver, kidney and brain tissues. Administration of B in a dose-dependent manner also reversed malathion-induced oxidative stress, lipid peroxidation (LPO) and antioxidant enzyme activity. Moreover, B exhibited protective action against malathion-induced histopathological changes in liver, kidney and brain tissues. These results demonstrate that, if used in a dose-dependent manner, B decreases malathion-induced oxidative stress, enhances the antioxidant defense mechanism and regenerates tissues in rats.

  19. The combination of trastuzumab and pertuzumab administered at approved doses may delay development of trastuzumab resistance by additively enhancing antibody-dependent cell-mediated cytotoxicity.

    Science.gov (United States)

    Tóth, Gábor; Szöőr, Árpád; Simon, László; Yarden, Yosef; Szöllősi, János; Vereb, György

    2016-10-01

    Although the recently concluded CLEOPATRA trial showed clinical benefits of combining trastuzumab and pertuzumab for treating HER2-positive metastatic breast cancer, trastuzumab monotherapy is still the mainstay in adjuvant settings. Since trastuzumab resistance occurs in over half of these cancers, we examined the mechanisms by which treatment of intrinsically trastuzumab-resistant and -sensitive tumors can benefit from the combination of these antibodies. F(ab')2 of both trastuzumab and pertuzumab were generated and validated in order to separately analyze antibody-dependent cell-mediated cytotoxicity (ADCC)-based and direct biological effects of the antibodies. Compared to monotherapy, combination of the two antibodies at clinically permitted doses enhanced the recruitment of natural killer cells responsible for ADCC, and significantly delayed the outgrowth of xenografts from intrinsically trastuzumab-resistant JIMT-1 cells. Antibody dose-response curves of in vitro ADCC showed that antibody-mediated killing can be saturated, and the two antibodies exert an additive effect at sub-saturation doses. Thus, the additive effect in vivo indicates that therapeutic tissue levels likely do not saturate ADCC. Additionally, isobole studies with the in vitro trastuzumab-sensitive BT-474 cells showed that the direct biological effect of combined treatment is additive, and surpasses the maximum effect of either monotherapy. Our results suggest the combined therapy is expected to give results that are superior to monotherapy, whatever the type of HER2-positive tumor may be. The combination of both antibodies at maximum clinically approved doses should thus be administered to patients to recruit maximum ADCC and cause maximum direct biological growth inhibition.

  20. Jaguar Procedures for Detonation Behavior of Explosives Containing Boron

    Science.gov (United States)

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

    2009-12-01

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

  1. Seromucosal transport of intravenously administered carbamazepine is not enhanced by oral doses of activated charcoal in rats.

    Science.gov (United States)

    Eyer, Florian; Jung, Nicole; Neuberger, Heidi; Witte, Andreas; Poethko, Thorsten; Henke, Julia; Zilker, Thomas

    2008-03-01

    The fate of carbamazepine after intravenous injection in rats (n = 24) and the influence of activated charcoal on the kinetics was investigated. After randomization to four groups (n = 6, each), plasma concentration and the quantities of carbamazepine and metabolites excreted into bile, urine and intestine were determined using an in situ perfusion model of the small intestine (Ringer's solution) with or without orally administered activated charcoal (AC+; AC-) and with or without bile duct cannulation (BD+; BD-). The cumulative amount of carbamazepine and metabolites exsorbed into the small intestine within 3.5 hr after intravenous injection was about 15% in BD- animals and about 3% in BD+ animals. About 20% of the dose was detected in the externalized bile. Activated charcoal did not influence the amount exsorbed into the small intestine. Terminal half-life in plasma ranged from 159 min. to 194 min. within the four treatment groups without statistical significant difference (P = 0.751). Correspondingly, the area under the curve did not vary significantly and ranged between 1.13 and 1.41 g/min./l (P = 0.378). Excretion of carbamazepine and metabolites into urine varied between 3% and 6% of dose within all groups and showed close correlation with diuresis. In an identical experimental approach using a 2-fold intestinal perfusion rate (50 ml/hr; n = 8), no fundamental changes compared to the main experiment regarding pharmacokinetics of carbamazepine were observed. The lack of effect of activated charcoal on the elimination of carbamazepine and metabolites must be contributed to the small amount of the drug being exsorbed into the intestine and may be further influenced by reduced intestinal permeability of carbamazepine and metabolites or inadequate luminal stirring.

  2. Probing the structures of neutral boron clusters using infrared/vacuum ultraviolet two color ionization: B[sub 11], B[sub 16], and B[sub 17

    NARCIS (Netherlands)

    Romanescu, C.; Harding, D. J.; Fielicke, A.; Wang, L. S.

    2012-01-01

    The structures of neutral boron clusters, B11, B16, and B17, have been investigated using vibrational spectroscopy and ab initio calculations. Infrared absorption spectra in the wavelength range of 650 to 1550 cm−1 are obtained for the three neutral boron clusters from the enhancement of their near-

  3. Detection of HbA(1c) by boronate affinity immunoassay using bacterial magnetic particles.

    Science.gov (United States)

    Tanaka, T; Matsunaga, T

    2001-12-01

    We have developed a boronate affinity immunoassay system using m-aminophenylboronic acid (mAPB) coupling to bacterial magnetic particles (BMPs). Homobifunctional crosslinker, Bis-(succcimidyl)suberate (BS3), was employed for preparation of mAPB-BMPs conjugates (mAPB-BMPs). Quantities of HbA(1c) on mAPB-BMPs were evaluated based on luminescence from alkaline phosphatase-conjugated anti-Hb antibody (ALP-antibody) binding to HbA(1c) on the BMP surface. The binding of HbA(1c) to mAPB-BMPs occurred gradually and was almost completed within 10 mm. The coupling reaction is enhanced due to static electric interaction between the positive charges on HbA(1c) and negative charges on BMPs. The amount of HbA(1c) binding to mAPB-BMPs increased with increasing sodium chloride concentrations in the range of 0-100 mM. However, the amount of Hb binding to mAPB-BMPs also increased in high concentration of sodium chloride. The Hb binding to mAPB-BMPs was detached from mAPB-BMPs when Hb-mAPB-BMPs were washed with low salt buffer. This indicates that Hb is nonspecifically adsorbed onto the surface of mAPB-BMPs in high concentration of sodium chloride. These results suggest that selective separation of HbA(1c) using mAPB-BMPs can be achieved with these conditions. A dose-response curve was obtained between luminescence intensity and HbA(1c) concentration using a fully automated boronate affinity immunoassay. A linear relationship between luminescence intensity and HbA(1c) concentration was obtained in the range of 10-10(4) ng/ml.

  4. Synthesis of Boron Nanowires, Nanotubes, and Nanosheets

    Directory of Open Access Journals (Sweden)

    Rajen B. Patel

    2015-01-01

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

  5. Prediction of boron carbon nitrogen phase diagram

    Science.gov (United States)

    Yao, Sanxi; Zhang, Hantao; Widom, Michael

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

  6. First application of dynamic infrared imaging in boron neutron capture therapy for cutaneous malignant melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Santa Cruz, G. A.; Gonzalez, S. J.; Bertotti, J.; Marin, J. [Departamento de Instrumentacion y Control, Comision Nacional de Energia Atomica, Avenida del Libertador 8250, 1429 Buenos Aires (Argentina); Departamento de Instrumentacion y Control, Comision Nacional de Energia Atomica, Avenida del Libertador 8250, 1429 Buenos Aires (Argentina) and CONICET, Avenida Rivadavia 1917, 1033 Buenos Aires (Argentina); Universidad Favaloro, Solis 453, 1078 Buenos Aires (Argentina)

    2009-10-15

    Purpose: The purpose of this study is to assess the potential of dynamic infrared imaging (DIRI) as a functional, noninvasive technique for evaluating the skin acute toxicity and tumor control within the framework of the Argentine boron neutron capture therapy (BNCT) program for cutaneous malignant melanoma. Methods: Two patients enrolled in the Argentine phase I/II BNCT clinical trial for cutaneous malignant melanoma were studied with DIRI. An uncooled infrared camera, providing a video output signal, was employed to register the temperature evolution of the normal skin and tumor regions in patients subjected to a mild local cooling (cold stimulus). In order to study the spatial correlation between dose and acute skin reactions, three-dimensional representations of the superficial dose delivered to skin were constructed and cameralike projections of the dose distribution were coregistered with visible and infrared images. Results: The main erythematous reaction was observed clinically between the second and fifth week post-BNCT. Concurrently, with its clinical onset, a reactive increase above the basal skin temperature was observed with DIRI in the third week post-BNCT within regions that received therapeutic doses. Melanoma nodules appeared as highly localized hyperthermic regions. 2 min after stimulus, these regions reached a temperature plateau and increased in size. Temperature differences with respect to normal skin up to 10 deg. C were observed in the larger nodules. Conclusions: Preliminary results suggest that DIRI, enhanced by the application of cold stimuli, may provide useful functional information associated with the metabolism and vasculature of tumors and inflammatory processes related to radiation-induced changes in the skin as well. These capabilities are aimed at complementing the clinical observations and standard imaging techniques, such as CT and Doppler ultrasound.

  7. Implications for clinical treatment from the micrometer site dosimetric calculations in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Trent L. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37901 (United States)], E-mail: tnichol2@utk.edu; Kabalka, George W. [Department of Chemistry, University of Tennessee, Knoxville, TN 37901 (United States); Miller, Laurence F. [Department of Nuclear and Radiological Engineering, University of Tennessee, Knoxville, TN 37901 (United States); McCormack, Michael T. [Department of Medicine, University of Tennessee Graduate School of Medicine, Knoxville, TN 37920 (United States); Johnson, Andrew [Rush University Medical Center, Chicago, IL 60612 (United States)

    2009-07-15

    Boron neutron capture therapy has now been used for several malignancies. Most clinical trials have addressed its use for the treatment of glioblastoma multiforme. A few trials have focused on the treatment of malignant melanoma with brain metastases. Trial results for the treatment of glioblastoma multiforme have been encouraging, but have not achieved the success anticipated. Results of trials for the treatment of malignant melanoma have been very promising, though with too few patients for conclusions to be drawn. Subsequent to these trials, regimens for undifferentiated thyroid carcinoma, hepatic metastases from adenocarcinoma of the colon, and head and neck malignancies have been developed. These tumors have also responded well to boron neutron capture therapy. Glioblastoma is an infiltrative tumor with distant individual tumor cells that might create a mechanism for therapeutic failure though recurrences are often local. The microdosimetry of boron neutron capture therapy can provide an explanation for this observation. Codes written to examine the micrometer scale energy deposition in boron neutron capture therapy have been used to explore the effects of near neighbor cells. Near neighbor cells can contribute a significantly increased dose depending on the geometric relationships. Different geometries demonstrate that tumors which grow by direct extension have a greater near neighbor effect, whereas infiltrative tumors lose this near neighbor dose which can be a significant decrease in dose to the cells that do not achieve optimal boron loading. This understanding helps to explain prior trial results and implies that tumors with small, closely packed cells that grow by direct extension will be the most amenable to boron neutron capture therapy.

  8. Low dose prospective ECG-gated delayed enhanced dual-source computed tomography in reperfused acute myocardial infarction comparison with cardiac magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wang Rui, E-mail: rui_wang1979@yahoo.cn [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang Zhaoqi, E-mail: zhaoqi5000@vip.sohu.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Xu Lei, E-mail: leixu2001@hotmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Ma Qin, E-mail: tel1367@gmail.com [Department of Emergency, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); He Yi, E-mail: heyi139@sina.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Lu Dongxu, E-mail: larry.hi@163.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Yu Wei, E-mail: yuwei02@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Fan Zhanming, E-mail: fanzm120@tom.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)

    2011-11-15

    Purpose: To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR). Material and methods: Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR. Results: In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa = 0.85, p < 0.001), and on transmural and subendocardial infarction type comparison (kappa = 0.82, p < 0.001, kappa = 0.52, p < 0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02 {+-} 9.57 HU vs. 72.63 {+-} 7.32 HU, p < 0.001). Radiation dose of prospectively ECG-gating protocol were 0.99 {+-} 0.08 mSv (0.82-1.19 mSv). Conclusions: Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.

  9. Composite Reinforcement using Boron Nitride Nanotubes

    Science.gov (United States)

    2014-05-09

    Final 3. DATES COVERED (From - To) 11-Mar-2013 to 10-Mar-2014 4. TITLE AND SUBTITLE Composite Reinforcement using Boron Nitride Nanotubes...AVAILABILITY STATEMENT Approved for public release. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Boron nitride nanotubes have been proposed as a...and titanium (Ti) metal clusters with boron nitride nanotubes (BNNT). First-principles density-functional theory plus dispersion (DFT-D) calculations

  10. Oxygen radical functionalization of boron nitride nanosheets

    OpenAIRE

    MAY, PETER; Coleman, Jonathan; MCGOVERN, IGNATIUS; GOUNKO, IOURI; Satti, Amro

    2012-01-01

    PUBLISHED The covalent chemical functionalization of exfoliated hexagonal boron-nitride nanosheets (BNNSs) is achieved by the solution phase oxygen radical functionalization of boron atoms in the h-BN lattice. This involves a two-step procedure to initially covalently graft alkoxy groups to boron atoms and the subsequent hydrolytic defunctionalisation of the groups to yield hydroxyl-functionalized BNNSs (OH-BNNSs). Characterization of the functionalized-BNNSs using HR-TEM, Raman, UV-Vis, F...

  11. Comportamento da alface americana em função do uso de doses e épocas de aplicação de boro em cultivo de inverno Behavior of crisp head lettuce as a result of doses and application times of boron in winter crop

    Directory of Open Access Journals (Sweden)

    Jony E. Yuri

    2004-09-01

    Full Text Available Avaliou-se a influência de doses de bórax sobre o rendimento e qualidade pós-colheita da alface americana (Lactuca sativa L., em três ensaios distintos conduzidos de junho a agosto/2002, no município de Três Pontas (MG. Utilizou-se o delineamento de blocos ao acaso com cinco doses de bórax (0,00; 0,75; 1,50; 2,25 e 3,00 kg ha-1 e quatro repetições, aplicadas em três diferentes épocas via foliar (14; 21 e 28 dias após o transplantio. A massa fresca total apresentou efeito quadrático no qual a dose de 1,58 kg ha-1 de bórax resultou em maior rendimento. Verificou-se variação de 795 a 829 g planta-1 entre as épocas de aplicação, sem diferirem estatisticamente entre si. A aplicação de 1,71 kg ha-1 de bórax possibilitou a obtenção de maior massa fresca comercial. O melhor resultado (563 g planta-1 foi obtido na aplicação aos 21 dias. Esta data também contribuiu na obtenção de maior circunferência da cabeça (41,7 cm, sendo significativamente superior à aplicação aos 28 dias (40,6 cm. Não foram observados efeitos significativos para o comprimento de caule entre os tratamentos. A dose de 1,55 kg ha-1 de bórax proporcionou uma melhor conservação da alface mantida durante 20 dias em câmara-fria.The influence of doses of borax on yield and post harvest quality of crisp head lettuce (Lactuca sativa L. was evaluated. Three distinct trials were conducted in Tres Pontas, Minas Gerais State, Brazil, from June to August 2002. The randomized block design with five doses of borax (0.00; 0.75; 1.50; 2.25 and 3.00 kg.ha-1 and four replicates, applied foliarly at different times (14; 21 and 28 days after transplanting was evaluated. The total fresh matter presented a quadratic effect, where the dose of 1.58 kg ha-1 of borax resulted in a greater yield. A range of 795 to 829 g plant-1 between different application times, with no statistical significant differences was observed. The application of 1.71 kg ha-1 of borax resulted in

  12. Boron-10 ABUNCL Active Testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-09

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

  13. Metronomic Doses of Temozolomide Enhance the Efficacy of Carbon Nanotube CpG Immunotherapy in an Invasive Glioma Model

    Science.gov (United States)

    Guo, Qin; Zhang, Ian; Gao, Hang; Yanyan, Song; Chen, Xuebo; Weng, Yiming; Da Fonseca, Anna; Shah, Sunny; Manuel, Edwin R.; Zhang, Leying; Vonderfecht, Steven L.; Alizadeh, Darya; Berlin, Jacob M.; Badie, Behnam

    2016-01-01

    Even when treated with aggressive current therapies, most patients with glioblastoma survive less than two years. Rapid tumor growth, an invasive nature, and the blood-brain barrier, which limits the penetration of large molecules into the brain, all contribute to the poor tumor response associated with conventional therapies. Immunotherapy has emerged as a therapeutic approach that may overcome these challenges. We recently reported that single-walled carbon nanotubes (SWCNTs) can be used to dramatically increase the immunotherapeutic efficacy of CpG oligonucleotides in a mouse model of glioma. Following implantation in the mouse brain, the tumor cell line used in these previous studies (GL261) tends to form a spherical tumor with limited invasion into healthy brain. In order to evaluate SWCNT/CpG therapy under more clinically-relevant conditions, here we report the treatment of a more invasive mouse glioma model (K-Luc) that better recapitulates human disease. In addition, a CpG sequence previously tested in humans was used to formulate the SWCNT/CpG which was combined with temozolomide, the standard of care chemotherapy for glioblastoma patients. We found that, following two intracranial administrations, SWCNT/CpG is well-tolerated and improves the survival of mice bearing invasive gliomas. Interestingly, the efficacy of SWCNT/CpG was enhanced when combined with temozolomide. This enhanced anti-tumor efficacy was correlated to an increase of tumor-specific cytotoxic activity in splenocytes. These results reinforce the emerging understanding that immunotherapy can be enhanced by combining it with chemotherapy and support the continued development of SWCNT/CpG. PMID:26829221

  14. Metronomic Doses of Temozolomide Enhance the Efficacy of Carbon Nanotube CpG Immunotherapy in an Invasive Glioma Model.

    Directory of Open Access Journals (Sweden)

    Mao Ouyang

    Full Text Available Even when treated with aggressive current therapies, most patients with glioblastoma survive less than two years. Rapid tumor growth, an invasive nature, and the blood-brain barrier, which limits the penetration of large molecules into the brain, all contribute to the poor tumor response associated with conventional therapies. Immunotherapy has emerged as a therapeutic approach that may overcome these challenges. We recently reported that single-walled carbon nanotubes (SWCNTs can be used to dramatically increase the immunotherapeutic efficacy of CpG oligonucleotides in a mouse model of glioma. Following implantation in the mouse brain, the tumor cell line used in these previous studies (GL261 tends to form a spherical tumor with limited invasion into healthy brain. In order to evaluate SWCNT/CpG therapy under more clinically-relevant conditions, here we report the treatment of a more invasive mouse glioma model (K-Luc that better recapitulates human disease. In addition, a CpG sequence previously tested in humans was used to formulate the SWCNT/CpG which was combined with temozolomide, the standard of care chemotherapy for glioblastoma patients. We found that, following two intracranial administrations, SWCNT/CpG is well-tolerated and improves the survival of mice bearing invasive gliomas. Interestingly, the efficacy of SWCNT/CpG was enhanced when combined with temozolomide. This enhanced anti-tumor efficacy was correlated to an increase of tumor-specific cytotoxic activity in splenocytes. These results reinforce the emerging understanding that immunotherapy can be enhanced by combining it with chemotherapy and support the continued development of SWCNT/CpG.

  15. Increasing ketamine dose enhances the anaesthetic properties of ketamine-xylazine-midazolam combinations in growing pigs : short communication

    Directory of Open Access Journals (Sweden)

    R.A. Ajadi

    2008-05-01

    Full Text Available The influence of increasing the dosage of ketamine on anaesthesia induced by a combination of ketamine, xylazine and midazolam in pigs was determined by assessing the onset of action (OAN, duration of analgesia (DAN, anaesthesia time (ANT, and recovery time (RCT in 10 growing pigs (Mean weight: 18.2 ± 1.65 kg receiving either 10 mg / kg intramuscular (i.m injection of 10 % ketamine, 2 mg / kg i.m injection of 2 % xylazine and 0.25 mg / kg i.m injection of 0.1%midazolam (K10XM or 20 mg / kg i.m injection of ketamine and 2 mg / kg i.m injection of xylazine and 0.25 mg / kg i.m injection of 0.1 % midazolam (K20XM. In addition, the heart rates (HR, respiratory rates (RR and rectal temperatures (RT were determined immediately after drug administration and at 10 minute intervals over a period of 60 minutes. Analgesia was assessed by the response of the pigs to artery forceps applied at the interdigital space. Recovery was determined as pigs' ability to stand without ataxia. Data were expressed as mean ± SEM while anaesthetic indices were compared using Student's t-tests. AP value of 0.05 was accepted as significant in all cases. In this study, both the OAN and RCT were significantly (P < 0.05 shorter in K10XM (1.4 ± 0.2 min; 7.8 ± 2.2 min than in K20XM (2.2 ± 0.2; 18.6 ± 1.4 min respectively. Similarly, the duration of anaesthesia was significantly (P < 0.05 shorter in K10XM (55.4 ± 8.4 min than in K20XM (92.0 ± 13.6 min. The pigs that received K20XM combination had analgesia of duration of 41.4±12.6 min while those that received K10XM combination had no analgesia. However, the HR, RR, and RT were not significantly (P > 0.05 different between K10XM and K20XM. It was therefore concluded that the lower dose ketamine combination is better for the induction of anaesthesia, while the higher dose ketamine combination is preferable for surgery of short duration in pigs.

  16. Boron deposition from fused salts. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.L.

    1980-08-01

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

  17. Mineral resource of the month: boron

    Science.gov (United States)

    Crangle, Robert D.

    2012-01-01

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

  18. 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%.

  19. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S., E-mail: ramp@iitm.ac.in

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  20. Conduction mechanism in boron carbide

    Science.gov (United States)

    Wood, C.; Emin, D.

    1984-01-01

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

  1. PECVD Silicon Nitride Passivation on Boron Emitter: The Analysis of Electrostatic Charge on the Interface Properties

    Directory of Open Access Journals (Sweden)

    Natalita M. Nursam

    2010-01-01

    Full Text Available The dependence of surface recombination of boron diffused and undiffused silicon surfaces passivated with a-SiN:H on the net charge density is investigated in detail. The films are deposited by plasma-enhanced chemical vapour deposition using a 2.45 GHz microwave remote plasma system. The surface charge density on the samples is varied by depositing charge using a corona discharge chamber. Excess carrier lifetime, capacitance-voltage, and Kelvin probe measurements are combined to determine the surface recombination velocity and emitter saturation current density as a function of net charge density. Our results show that the application of negative charge causes a substantial reduction in the surface recombination of samples with boron diffused emitters, even for high boron surface concentrations of 5×1019 cm−3. The significant difference observed in surface recombination between boron diffused and undiffused sample under accumulation implies that the presence of boron diffusion has results in some degradation of the Si-SiN interface. Further, (111 oriented surfaces appear more sensitive to the boron surface concentration than (100 oriented surfaces.

  2. Boron containing poly-(lactide-co-glycolide) (PLGA) scaffolds for bone tissue engineering.

    Science.gov (United States)

    Doğan, Ayşegül; Demirci, Selami; Bayir, Yasin; Halici, Zekai; Karakus, Emre; Aydin, Ali; Cadirci, Elif; Albayrak, Abdulmecit; Demirci, Elif; Karaman, Adem; Ayan, Arif Kursat; Gundogdu, Cemal; Sahin, Fikrettin

    2014-11-01

    Scaffold-based bone defect reconstructions still face many challenges due to their inadequate osteoinductive and osteoconductive properties. Various biocompatible and biodegradable scaffolds, combined with proper cell type and biochemical signal molecules, have attracted significant interest in hard tissue engineering approaches. In the present study, we have evaluated the effects of boron incorporation into poly-(lactide-co-glycolide-acid) (PLGA) scaffolds, with or without rat adipose-derived stem cells (rADSCs), on bone healing in vitro and in vivo. The results revealed that boron containing scaffolds increased in vitro proliferation, attachment and calcium mineralization of rADSCs. In addition, boron containing scaffold application resulted in increased bone regeneration by enhancing osteocalcin, VEGF and collagen type I protein levels in a femur defect model. Bone mineralization density (BMD) and computed tomography (CT) analysis proved that boron incorporated scaffold administration increased the healing rate of bone defects. Transplanting stem cells into boron containing scaffolds was found to further improve bone-related outcomes compared to control groups. Additional studies are highly warranted for the investigation of the mechanical properties of these scaffolds in order to address their potential use in clinics. The study proposes that boron serves as a promising innovative approach in manufacturing scaffold systems for functional bone tissue engineering.

  3. Boron removal efficiency from Red Sea water using different SWRO/BWRO membranes

    KAUST Repository

    Rahmawati, Karina

    2012-12-01

    Seawater reverse osmosis (SWRO) desalination process provides high quality of fresh water. However, due to some operational constraints mainly scaling control some trace contaminant removal, such as acceptable boron concentration, cannot be achieved in a single pass SWRO system. The objective of this study was to investigate the efficiency of five difference reverse osmosis (RO) membranes (seawater SW and brackish water BW) provided by different manufacturers for boron removal. RO experiments using pretreated real Red Sea water were conducted in parallel to compare membrane performance under the same operating conditions. As expected, results showed that boron rejection increased as the feed pH increased. This was caused by dissociation of boric acid to negatively charged borate ions and more negatively charged membrane surface at elevated pH which enhanced boron rejection. Single pass RO system, with and without elevating the pH, may not be sufficient for two reasons. First, boron concentration in permeate does not fulfill local regulations (<0.5ppm). Second, severe scaling occurs due to operation in alkaline condition, since Ca 2+ and Mg 2+ concentrations are still high to cause salts precipitation. Techno-economical study was performed to select the best configuration and membrane giving the highest performance in terms of boron and TDS rejections and energy consumption. © 2012 Elsevier B.V.

  4. Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, Ahmed A. [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Nuclear and Radiation Engineering, Faculty of Engineering, Alexandria University, Alexandria (Egypt); Fadlallah, Mohamed M. [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Department of Physics, Faculty of Science, Benha University, Benha (Egypt); Badawi, Ashraf [Center for Nanotechnology, Zewail City of Science and Technology, Giza 12588 (Egypt); Maarouf, Ahmed A., E-mail: ahmed.maarouf@egnc.gov.eg [Center for Fundamental Physics, Zewail City of Science and Technology, Giza 12588 (Egypt); Egypt Nanotechnology Center & Department of Physics, Faculty of Science, Cairo University, Giza 12613 (Egypt)

    2016-07-30

    Highlights: • Doping boron nitride sheets with aluminum or gallium atoms significantly enhances their molecular adsorption properties. • Adsorption of glucose or glucosamine on Al- and Ga-doped boron nitride sheets changes the band gap. • Doping concentration changes the bad gap, but has a minor effect on the adsorption energy. - Abstract: Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-doped boron nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

  5. Distinct enhancement of sub-bandgap photoresponse through intermediate band in high dose implanted ZnTe:O alloys

    Science.gov (United States)

    Li, Jing; Ye, Jiandong; Ren, Fangfang; Tang, Dongming; Yang, Yi; Tang, Kun; Gu, Shulin; Zhang, Rong; Zheng, Youdou

    2017-03-01

    The demand for high efficiency intermediate band (IB) solar cells is driving efforts in producing high quality IB photovoltaic materials. Here, we demonstrate ZnTe:O highly mismatched alloys synthesized by high dose ion implantation and pulsed laser melting exhibiting optically active IB states and efficient sub-gap photoresponse, as well as investigate the effect of pulsed laser melting on the structural and optical recovery in detail. The structural evolution and vibrational dynamics indicates a significant structural recovery of ZnTe:O alloys by liquid phase epitaxy during pulsed laser melting process, but laser irradiation also aggravates the segregation of Te in ZnTe:O alloys. A distinct intermediate band located at 1.8 eV above valence band is optically activated as evidenced by photoluminescence, absorption and photoresponse characteristics. The carrier dynamics indicates that carriers in the IB electronic states have a relatively long lifetime, which is beneficial for the fast separation of carriers excited by photons with sub-gap energy and thus the improved overall conversion efficiency. The reproducible capability of implantation and laser annealing at selective area enable the realization of high efficient lateral junction solar cells, which can ensure extreme light trapping and efficient charge separation.

  6. Contamination of urban garden soils with copper, boron, and lead

    Energy Technology Data Exchange (ETDEWEB)

    Purves, D.

    1967-04-01

    Spectrochemical analysis of representative samples of topsoil from urban gardens and from individual fields in rural areas indicates that the level of total copper, EDTA-extractable copper, water-soluble boron, and acetic-acid extractable lead are markedly enhanced in urban areas. No significant differences were discovered between levels of these elements in soils from built-up areas in small towns and large conurbations. These results suggest the possibility of general enhancement of the trace element content of plants grown in private gardens in built-up areas.

  7. HDAC inhibitors enhance the lethality of low dose salinomycin in parental and stem-like GBM cells.

    Science.gov (United States)

    Booth, Laurence; Roberts, Jane L; Conley, Adam; Cruickshanks, Nichola; Ridder, Thomas; Grant, Steven; Poklepovic, Andrew; Dent, Paul

    2014-03-01

    The present studies determined whether the antibiotic salinomycin interacted with HDAC inhibitors to kill primary human GBM cells. Regardless of PTEN, ERBB1, or p53 mutational status salinomycin interacted with HDAC inhibitors in a synergistic fashion to kill GBM cells. Inhibition of CD95/Caspase 8 or of CD95/RIP-1/AIF signaling suppressed killing by the drug combination. Salinomycin increased the levels of autophagosomes that correlated with increased p62 and LC3II levels; valproate co-treatment correlated with reduced LC3II and p62 expression, and increased caspase 3 cleavage. Molecular inhibition of autophagosome formation was protective against drug exposure. The drug combination enhanced eIF2α phosphorylation and decreased expression of MCL-1 and phosphorylation of mTOR and p70 S6K. Activation of p70 S6K or mTOR promoted cell survival in the face of combined drug exposure. Overexpression of BCL-XL or c-FLIP-s was protective. Collectively our data demonstrate that the lethality of low nanomolar concentrations of salinomycin are enhanced by HDAC inhibitors in GBM cells and that increased death receptor signaling together with reduced mitochondrial function are causal in the combinatorial drug necro-apoptotic killing effect.

  8. A Contribution to the Understanding of the Combined Effect of Nitrogen and Boron in Grey Cast Iron

    DEFF Research Database (Denmark)

    Strande, Knud; Tiedje, Niels Skat; Chen, Ming

    2017-01-01

    iron microstructure. Both graphite flake formation and matrix formation are influenced. However, the obtained effects differ considerably between different reported investigations. This investigation deals with the combined effect of nitrogen and boron and how it is possible to utilize this effect...... to enhance material properties in heavy grey iron castings. It is shown that the controlled additions of nitrogen and boron can be used to control the microstructure of thick section grey iron castings. A plausible theory for the formation of boron nitride nuclei effective for graphite growth is presented....

  9. Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy

    Science.gov (United States)

    Herrera, María S.; González, Sara J.; Minsky, Daniel M.; Kreiner, Andrés J.

    2010-08-01

    Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator-based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton-induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose-volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator-based BNCT treatment.

  10. Efficient tumor regression by a single and low dose treatment with a novel and enhanced formulation of thermosensitive liposomal doxorubicin.

    Science.gov (United States)

    Tagami, Tatsuaki; Ernsting, Mark J; Li, Shyh-Dar

    2011-06-10

    We have developed a novel and simplified thermosensitive liposomal formulation (HaT: Hyperthermia-activated cytoToxic) composed of DPPC lipid and Brij78 (96:4, molar ratio). The HaT nanoparticles were loaded with doxorubicin (DOX) with >95% efficiency when a pH gradient method and a drug/lipid ratio of 1/20 (w/w) were applied. Drug release from the HaT formulation was significantly faster at 40-41°C (100% release in 2-3min) with 3.4-fold increased membrane permeability compared to the LTSL (lyso-lipid temperature sensitive liposomes; DPPC: MSPC: DSPE-PEG(2000)=86:10:4, molar ratio), a formulation that is currently in clinical trials. Both formulations displayed similar stability at 37°C in serum (10-20% release in 30min), which corresponds to their comparable pharmacokinetics in the unheated mice. An approximately 1.4-fold increased drug delivery to the locally heated tumor (~43°C) was detected with HaT-DOX compared to LTSL-DOX. Moreover, when compared with free DOX, HaT enhanced drug uptake in the heated tumor by 5.2-fold and reduced drug delivery to the heart by 15-fold. A single i.v. treatment with HaT-DOX at 3mg DOX/kg in combination with localized hyperthermia demonstrated enhanced tumor regression compared to LTSL-DOX and free DOX, and exhibited little toxicity.

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

    Science.gov (United States)

    Durmazuçar, Hasan H.; Gündüz, Güngör

    2000-12-01

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

  12. Interstitial Boron-Doped TiO2 Thin Films: The Significant Effect of Boron on TiO2 Coatings Grown by Atmospheric Pressure Chemical Vapor Deposition.

    Science.gov (United States)

    Quesada-González, Miguel; Boscher, Nicolas D; Carmalt, Claire J; Parkin, Ivan P

    2016-09-28

    The work presented here describes the preparation of transparent interstitial boron-doped TiO2 thin-films by atmospheric pressure chemical vapor deposition (APCVD). The interstitial boron-doping, on TiO2, proved by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), is shown to enhance the crystallinity and significantly improve the photocatalytic activity of the TiO2 films. The synthesis, highly suitable for a reel-to-reel process, has been carried out in one step.

  13. Boron Separation by the Two-step Ion-Exchange for the Isotopic Measurement of Boron

    Institute of Scientific and Technical Information of China (English)

    WANG,Qing-Zhong(王庆忠); XIAO,Ying-Kai(肖应凯); WANG,Yun-Hui(王蕴惠); ZHANG,Chong-Geng(张崇耿); WEI,Hai-Zhen(魏海珍)

    2002-01-01

    An improved procedure for extraction and purification of boron from natural samples is presented. The separation and purification of boron was carried out using a boron-specific resin, Amberlite IRA743, and a mixed ion exchange resin,Dowex 50W × 8 and Ion Exchanger Ⅱ resin. Using the mixed ion exchange resin which adsorbs all cations and anions except boron, the HCl and other cations and anions left in eluant from the Amberlite IRA 743 were removed effectively. In this case, boron loss can be avoided because the boron-bearing solution does not have to be evaporated to reach dryness to dislodge HCl. The boron recovery ranged from 97.6% to 102% in this study. The isotopic fractionation of boron can be negligible within the precision of the isotopic measurement. The results show that boron separation for the isotopic measurement by using both Amberlite IRA 743 resin and the mixed rein is more effective than that using Amberlite IRA 743 resin alone. The boron in samples of brine, seawater, rock, coral and foraminifer were separated by this procedure. Boron isotopic compositions of these samples were measured by thermal ionization mass spectrometry in this study.

  14. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV.

    Science.gov (United States)

    Seidenbusch, M; Harder, D; Regulla, D

    2014-05-01

    The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual

  15. Kinetic characterization of glucose aerodehydrogenase from Aspergillus niger EMS-150-F after optimizing the dose of mutagen for enhanced production of enzyme.

    Science.gov (United States)

    Umbreen, Huma; Zia, Muhammad Anjum; Rasul, Samreen

    2013-12-01

    In the present study enhanced production of glucose aerodehydrogenase from Aspergillus niger has been achieved after optimizing the dose of chemical mutagen ethyl methane sulfonate (EMS) that has not been reported earlier. Different doses of mutagen were applied and a strain was developed basing upon the best production. The selected strain Aspergillus niger EMS-150-F was optimized for nutrient requirements in order to produce enzyme through fermentation and the results showed the best yield at 2% corn steep liquor (CSL), 36 hours fermentation time, pH 5, 30 °C temperature, 0.3% KH2PO4, 0.3% urea and 0.06% CaCO3. The enzyme was then purified and resulted in 57.88 fold purification with 52.12% recovery. On kinetic characterization, the enzyme showed optimum activity at pH 6 and temperature 30 °C. The Michaelis-Menton constants (K(m), Vmax, Kcat and Kcat/K(m)) were 20 mM, 45.87 U mL(-1), 1118.81 s(-1) and 55.94 s(-1) mM(-1), respectively. The enzyme was found to be thermally stable and the enthalpy and free energy showed an increase with increase in temperature and ΔS* was highly negative proving the enzyme from A. niger EMS-150-F resistant to temperature and showing a very little disorderliness.

  16. In-phantom two-dimensional thermal neutron distribution for intraoperative boron neutron capture therapy of brain tumours

    Science.gov (United States)

    Yamamoto, T.; Matsumura, A.; Yamamoto, K.; Kumada, H.; Shibata, Y.; Nose, T.

    2002-07-01

    The aim of this study was to determine the in-phantom thermal neutron distribution derived from neutron beams for intraoperative boron neutron capture therapy (IOBNCT). Gold activation wires arranged in a cylindrical water phantom with (void-in-phantom) or without (standard phantom) a cylinder styrene form placed inside were irradiated by using the epithermal beam (ENB) and the mixed thermal-epithermal beam (TNB-1) at the Japan Research Reactor No 4. With ENB, we observed a flattened distribution of thermal neutron flux and a significantly enhanced thermal flux delivery at a depth compared with the results of using TNB-1. The thermal neutron distribution derived from both the ENB and TNB-1 was significantly improved in the void-in-phantom, and a double high dose area was formed lateral to the void. The flattened distribution in the circumference of the void was observed with the combination of ENB and the void-in-phantom. The measurement data suggest that the ENB may provide a clinical advantage in the form of an enhanced and flattened dose delivery to the marginal tissue of a post-operative cavity in which a residual and/or microscopically infiltrating tumour often occurs. The combination of the epithermal neutron beam and IOBNCT will improve the clinical results of BNCT for brain tumours.

  17. Inhibition of IL-17A suppresses enhanced-tumor growth in low dose pre-irradiated tumor beds.

    Directory of Open Access Journals (Sweden)

    Eun-Jung Lee

    Full Text Available Ionizing radiation induces modification of the tumor microenvironment such as tumor surrounding region, which is relevant to treatment outcome after radiotherapy. In this study, the effects of pre-irradiated tumor beds on the growth of subsequently implanted tumors were investigated as well as underlying mechanism. The experimental model was set up by irradiating the right thighs of C3H/HeN mice with 5 Gy, followed by the implantation of HCa-I and MIH-2. Both implanted tumors in the pre-irradiated bed showed accelerated-growth compared to the control. Tumor-infiltrated lymphocyte (TIL levels were increased, as well as pro-tumor factors such as IL-6 and transforming growth factor-beta1 (TGF-β1 in the pre-irradiated group. In particular, the role of pro-tumor cytokine interleukin-17A (IL-17A was investigated as a possible target mechanism because IL-6 and TGF-β are key factors in Th17 cells differentiation from naïve T cells. IL-17A expression was increased not only in tumors, but also in CD4+ T cells isolated from the tumor draining lymph nodes. The effect of IL-17A on tumor growth was confirmed by treating tumors with IL-17A antibody, which abolished the acceleration of tumor growth. These results indicate that the upregulation of IL-17A seems to be a key factor for enhancing tumor growth in pre-irradiated tumor beds.

  18. Gadolinium-enhanced magnetic resonance angiography for hepato mesenteric vascular evaluation: single and double doses comparison in schistosomiasis patients; Estudo da circulacao hepatomesenterica pela angiografia por ressonancia magnetica com gadolinio: comparacao entre doses simples e dupla no estudo de pacientes esquistossomoticos

    Energy Technology Data Exchange (ETDEWEB)

    Caldana, Rogerio Pedreschi; Bezerra, Alexandre Sergio de Araujo; D' Ippolito, Giuseppe; Szejnfeld, Jacob [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. de Diagnostico por Imagem]. E-mail: rogercal@uol.com.br

    2006-07-15

    Objective: to evaluate the visibility of hepatomesenteric vascular segments by 3D gadolinium-enhanced magnetic resonance (MR) angiography and to compare the method effectiveness between two different gadolinium doses (single and double doses). Materials and methods: a prospective study was performed with 36 schistosomiasis patients who were submitted to 3D contrast-enhanced MR angiography. Scans were performed in a high-field equipment (1.5 T), with body coil and power injector for intravenous contrast administration. Contrast double doses (Gd-DTPA 0.2 mmol/kg) and single doses (0.1 mmol/kg) were randomly used respectively in 21 and 15 patients. Studies were interpreted by consensus between two observers who have rated the visualization degree of 25 proximal vascular segments without knowing the dose used. Results: proximal and calibrous vascular segments have presented higher visualization degree in the greatest part of the sample studied. The celiac trunk, common hepatic artery, splenic artery, proximal and medium third of superior mesenteric artery, portal vein, splenic vein and superior mesenteric vein have presented grade 2 visualization in more than 70% of the sample studied. As regards comparison between different doses, there was no significant difference (p < 0.05) in the visualization degree of several structures evaluated, between double dose and single dose groups, except for an isolate case of evaluation of right hepatic artery (p = 0.008) in which the single dose group has presented a higher frequency of grade 2 visualization with statistical significance. Conclusion: the visualization degree of hepato mesenteric vascular segments by 3D gadolinium-enhanced MR angiography is high, especially in the proximal and calibrous segments. The comparison between groups using single and double contrast doses has demonstrated similar results. (author)

  19. Possible toxicity of boron on sugar cane

    Energy Technology Data Exchange (ETDEWEB)

    Bravo C., M.

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

  20. Computational Evidence for the Smallest Boron Nanotube

    Institute of Scientific and Technical Information of China (English)

    Xian Jie LIN; Dong Ju ZHANG; Cheng Bu LIU

    2006-01-01

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

  1. Boron carbide whiskers produced by vapor deposition

    Science.gov (United States)

    1965-01-01

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

  2. 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.

  3. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    Wood, Charles

    1988-01-01

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

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

    Science.gov (United States)

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

    2014-11-01

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

  5. Monte Carlo assessment of boron neutron capture therapy for the treatment of breast cancer

    Directory of Open Access Journals (Sweden)

    Mundy Daniel W.

    2005-01-01

    Full Text Available For a large number of women who are diagnosed with breast cancer every year the avail able treatment options are effective, though physically and mentally taxing. This work is a starting point of a study of the efficacy of boron neutron capture therapy as an alternative treatment for HER-2+ breast tumors. Using HER-2-specific monoclonal anti bodies coupled with a boron-rich oligomeric phosphate diester, it may be possible to deliver sufficient amounts of 10B to a tumor of the breast to al low for selective cell destruction via irradiation by thermal neutrons. A comprehensive computational model (MCNP for thermal neutron irradiation of the breast is described, as well as the results of calculations made using this model, in order to determine the optimum boron concentration within the tumor for an effective boron neutron capture therapy treatment, as compared with traditional X-ray radiotherapy. The results indicate that a boron concentration of 50-60 mg per gram of tumor tissue is optimal when considering treatment times, dose distributions and skin sparing. How ever these results are based upon best-guess assumptions that must be experimentally verified.

  6. Tribological properties of boron nitride synthesized by ion beam deposition

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  7. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hao, E-mail: sunhao_robert@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Hou, Xin-Yi, E-mail: hxy_pumc@126.com [Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing (China); Xue, Hua-Dan, E-mail: bjdanna95@hotmail.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Li, Xiao-Guang, E-mail: xglee88@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Jin, Zheng-Yu, E-mail: zhengyu_jin@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Qian, Jia-Ming, E-mail: qjiaming57@gmail.com [Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Yu, Jian-Chun, E-mail: yu-jch@163.com [Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Zhu, Hua-Dong, E-mail: huadongzhu@hotmail.com [Department of Emergency, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China)

    2015-05-15

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  8. Boronated mesophase pitch coke for lithium insertion

    Science.gov (United States)

    Frackowiak, E.; Machnikowski, J.; Kaczmarska, H.; Béguin, F.

    Boronated carbons from mesophase pitch have been used as materials for lithium storage in Li/carbon cells. Doping by boron has been realized by co-pyrolysis of coal tar pitch with the pyridine-borane complex. Amount of boron in mesocarbon microbeads (MCMB) varied from 1.4 to 1.8 wt.% affecting the texture of carbon. Optical microscopy and X-ray diffractograms have shown tendency to more disordered structure for boron-doped carbon. The values of specific reversible capacity ( x) varied from 0.7 to 1.1 depending significantly on the final temperature of pyrolysis (700-1150°C). The optimal charge/discharge performance was observed for boronated carbon heated at 1000°C.

  9. Stabilization of boron carbide via silicon doping.

    Science.gov (United States)

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

    2015-01-14

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

  10. 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.

  11. Effects of boron doping in TiO2 nanotubes and the performance of dye-sensitized solar cells

    Science.gov (United States)

    Subramanian, Alagesan; Wang, Hong-Wen

    2012-06-01

    Titanium nanotubes doped with boron used as the photoelectrode for dye-sensitized solar cells were investigated. The materials were characterized by SEM, XRD, and UV-vis spectroscopy and their photoconversion efficiencies were evaluated. The chemical compositions of TiO2 nanotubes (TNA) and boron doped TNA (B-TNA) were identified by the energy dispersive X-ray spectroscopy (EDS). XRD evidenced the presence of anatase as the main phase and presented the existence of boron elements at interstitial sites between the TiO2 lattices. The UV-vis spectra indicated the narrowing of band gap upon doping boron into titanium nanotubes. The photovoltaic properties were measured by a current-voltage meter under AM1.5 simulated light radiation. The boron-doped TiO2 nanotube arrays showed an enhanced performance with a photocurrent density of 7.85 ± 0.20 mA/cm2 and an overall conversion efficiency (η) of 3.44 ± 0.10%. The enhanced performance was attributed to the enhanced electron injection rate and retardation of the charge recombination, which could be due to perfect matching between the LUMO of dye molecules and the conduction band of TiO2. Electrochemical impedance spectroscopy (EIS) measurement indicated the longer electron lifetime and reduced TiO2/dye/electrolyte interface resistance for boron doped TiO2 nanotubes than that of undoped TiO2 nanotubes.

  12. Full-scale simulation of seawater reverse osmosis desalination processes for boron removal: Effect of membrane fouling.

    Science.gov (United States)

    Park, Pyung-Kyu; Lee, Sangho; Cho, Jae-Seok; Kim, Jae-Hong

    2012-08-01

    The objective of this study is to further develop previously reported mechanistic predictive model that simulates boron removal in full-scale seawater reverse osmosis (RO) desalination processes to take into account the effect of membrane fouling. Decrease of boron removal and reduction in water production rate by membrane fouling due to enhanced concentration polarization were simulated as a decrease in solute mass transfer coefficient in boundary layer on membrane surface. Various design and operating options under fouling condition were examined including single- versus double-pass configurations, different number of RO elements per vessel, use of RO membranes with enhanced boron rejection, and pH adjustment. These options were quantitatively compared by normalizing the performance of the system in terms of E(min), the minimum energy costs per product water. Simulation results suggested that most viable options to enhance boron rejection among those tested in this study include: i) minimizing fouling, ii) exchanging the existing SWRO elements to boron-specific ones, and iii) increasing pH in the second pass. The model developed in this study is expected to help design and optimization of the RO processes to achieve the target boron removal at target water recovery under realistic conditions where membrane fouling occurs during operation.

  13. SU-E-T-231: Measurements of Gold Nanoparticle-Mediated Proton Dose Enhancement Due to Particle-Induced X-Ray Emission and Activation Products Using Radiochromic Films and CdTe Detector

    Energy Technology Data Exchange (ETDEWEB)

    Cho, J; Cho, S [Dept. of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX (United States); Manohar, N [Dept. of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX (United States); Medical Physics Program, Georgia Institute of Technology, Atlanta, GA (Georgia); Krishnan, S [Dept. of Radiation Oncology, UT MD Anderson Cancer Center, Houston, TX (United States)

    2014-06-01

    Purpose: There have been several reports of enhanced cell-killing and tumor regression when tumor cells and mouse tumors were loaded with gold nanoparticles (GNPs) prior to proton irradiation. While particle-induced xray emission (PIXE), Auger electrons, secondary electrons, free radicals, and biological effects have been suggested as potential mechanisms responsible for the observed GNP-mediated dose enhancement/radiosensitization, there is a lack of quantitative analysis regarding the contribution from each mechanism. Here, we report our experimental effort to quantify some of these effects. Methods: 5-cm-long cylindrical plastic vials were filled with 1.8 mL of either water or water mixed with cylindrical GNPs at the same gold concentration (0.3 mg Au/g) as used in previous animal studies. A piece of EBT2 radiochromic film (30-µm active-layer sandwiched between 80/175-µm outer-layers) was inserted along the long axis of each vial and used to measure dose enhancement due to PIXE from GNPs. Vials were placed at center-of-modulation (COM) and 3-cm up-/down-stream from COM and irradiated with 5 different doses (2–10 Gy) using 10-cm-SOBP 160-MeV protons. After irradiation, films were cleaned and read to determine the delivered dose. A vial containing spherical GNPs (20 mg Au/g) was also irradiated, and gamma-rays from activation products were measured using a cadmium-telluride (CdTe) detector. Results: Film measurements showed no significant dose enhancement beyond the experimental uncertainty (∼2%). There was a detectable activation product from GNPs, but it appeared to contribute to dose enhancement minimally (<0.01%). Conclusion: Considering the composition of EBT2 film, it can be inferred that gold characteristic x-rays from PIXE and their secondary electrons make insignificant contribution to dose enhancement. The current investigation also suggests negligible dose enhancement due to activation products. Thus, previously-reported GNP-mediated proton dose

  14. 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

    2014-06-01

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

  15. Promotion of the Growth of Boron-Carbide Nanowires

    Science.gov (United States)

    Kranov, Yanko; Zhang, Daqing; McIlroy, David; Norton, Grant

    2000-03-01

    Boron carbide, is a wide bandgap semiconductor (2.1eV) with a high melting temperature in excess of 2400^circC. Initial studies indicate that nanowires of boron carbide approximately 25 ~30 μm in length and less than 100 nm in diameter can be grown by the technique of plasma enhanced chemical vapor deposition by a mode of the vapor-liquid-solid mechanism [1] at relatively low temperatures ( ~1150^circC). Through the use of boron based eutectics such as FeB, NiB and PtB nanowire growth at temperatures below 1150^circC. These metal borides have successively lower melting temperatures, respectively. In this paper we will discuss a simple technique for making submicron metal boride particles, as well as a simple means of depositing them onto a surface. In addition, the effect of droplet size on nanowire diameter and the stability of the size of the metal boride droplet during growth will be discussed. These studies demonstrate that the surface can be selectively seeded thereby controlling the location of the nanowires, i.e. select area deposition. Lastly, the techniques and materials used to grow boron carbide nanowires can easily be used to grow other types of nanowires, as well as carbon nanotubes. [1]. D. N. McIlroy, Daqing Zhang, Robert M. Cohen, J. Wharton, Yongjun Geng, M. Grant Norton, G. De Stasio, B.Gilbert, L.Perfetti, J.H.Streiff, B.Broocks and J.L. McHale, Phys. Rev. B 60 (1999) 4874

  16. 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.

  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. Engineering design feasibility of low boron concentration core in PWR

    Energy Technology Data Exchange (ETDEWEB)

    Daing, A. T.; Kim, M. H. [Kyung Hee University, Yongin-shi, Gyeonggi-do, 446-701 Republic of Korea (Korea, Republic of); Woo, I.; Shon, S. R., E-mail: atdaing@khu.ac.k [Korea Nuclear Fuel, 1047 Daedukdaero, Yuseong-gu, Daejeon, 305-353 Republic of Korea (Korea, Republic of)

    2010-10-15

    In pressurized water reactor operation, higher level of soluble boron concentration could contribute higher impact from boron dilution situations, higher amount of liquid waste, and higher radiation dose to operators from higher corrosion potential to cladding and structure. Two practical and feasible means to reduce the maximum boron concentration were investigated in this study. A technically straightforward, possible means, can be achieved either by implementation of enriched boric acid (Eba) or by increasing more shim rod (fixed burnable absorber) worth. A simplest option is that the Eba is applied into reference core (Ref) design, OPR-1000 design, Ulchin unit-5 by allowing use of same fuel assemblies and core design without changing any nuclear design methodology used in that Ref design. Although results of Eba option proved its favorable power distribution and peaking factor, its moderator temperature coefficient (MTC) value reached positive, 3.25 pcm/ C at 40 EFPD which is beyond the design safety limit. An alternative option with more shim rods in fuel assemblies was tried with four types of integral burnable absorbers: gadolinia, integral fuel burnable absorber (Ifba), erbium and alumina boron carbide. Four core design candidates have been developed by keeping major engineering designs and preserving equivalent fuel enrichment level used in Ref design. However, all optimal designs were targeted to achieve comparable discharge burnup as well as favorable design safety parameters. The comparative analysis between Ref and optimal core designs is presented here. One of them is suggested as the most promising and favorable low boron core (Lbc) design in this framework. The proper combination of axial and radial enrichment zoning pattern in Lbc design candidate with Ifba-bearing fuel assemblies at equilibrium cycle, could bring 2 times narrower axial offset variation than that of Ref design, and maintain acceptable power peaking factor around 23% lower than

  19. Study on the Tribological Properties and Composition of W6Mo5Cr4V2 High Speed Steel Implanted by Boron

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-hai; XIONG Wan-quan; ZHANG Ping; TAN Jun; ZAHO Jun-jun

    2004-01-01

    Boron atoms were implanted into W6Mo5Cr4V2 high-speed steel (HSS) in CC-60 ion implantation machine to improve its tribological properties. The influence of boron implantation dose on the microhardness, friction coefficient and wear resistance of HSS were investigated. The experiment results showed that the implantation of boron can improve the tribological properties of W6Mo5Cr4V2 steel greatly. Then the phase and composition of implanted layer were analyzed by XRD and XPS. The analysisresult revealed that the interface between the implantation layer and substrate appeared to be mixed.With the increase of boron dose, the compound of δ-WB, CrB, BFe3 are the main additive phases, which supposed to be the main reason to improve the tribological properties of W6Mo5Cr4V2 steel.

  20. Phosphorous transient enhanced diffusion suppression and activation enhancement with cluster carbon co-implantation

    Energy Technology Data Exchange (ETDEWEB)

    Nakashima, Yoshiki; Hamamoto, Nariaki; Nagayama, Tsutomu; Koga, Yuji; Umisedo, Sei; Kawamura, Yasunori; Hashimoto, Masahiro; Onoda, Hiroshi [Nissin Ion Equipment Co., Ltd., 575 Kuze Tonoshiro-cho, Minami-ku, Kyoto, 601-8205 (Japan)

    2012-11-06

    Carbon co-implantation is well known as an effective method for suppressing boron/phosphorous transient enhanced diffusion (TED). Germanium pre-amorphization implantation (PAI) is usually applied prior to carbon co-implantation for suppressing channeling tail of dopants. In this study, cluster carbon was applied instead of the combination of germanium PAI and monomer carbon co-implantation prior to phosphorous implantation. Dependence of phosphorous activation and TED on amorphous layer thickness, carbon dose, carbon distribution and substrate temperature have been investigated. Cluster carbon implantation enables thick amorphous layer formation and TED suppression at the same time and low temperature implantation enhances the ability of amorphous layer formation so that shallow junction and low Rs can be achieved without Ge implantation.

  1. Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages.

    Directory of Open Access Journals (Sweden)

    Indusmita Routray

    Full Text Available Chemical mediators of inflammation (CMI are important in host defense against infection. The reduced capacity of host to induce the secretion of these mediators following infection is one of the factors in host susceptibility to infection. Boron, which has been suggested for its role in infection, is reported in this study to increase lymphocyte proliferation and the secretion of CMI by the lipopolysaccharide (LPS-stimulated peritoneal macrophages in BALB/c mice. Boron was administered to mice orally as borax at different doses for 10 consecutive days, followed by the stimulation of animals with ovalbumin and isolation of splenocytes for proliferation assay. The lymphocyte subsets were determined by flow cytometry in spleen cell suspension. The mediators of inflammation, TNF-α, IL-6, IL-1β and nitric oxide (NO, were measured in culture supernatant of LPS-primed macrophages isolated from borax treated mice. TNF and ILs were measured by ELISA. NO was determined by Griess test. The expression of inducible nitric oxide synthase (iNOS in macrophages was studied by confocal microscopy. Results showed a significant increase in T and B cell populations, as indicated by an increase in CD4 and CD19, but not CD8, cells. Boron further stimulated the secretion of TNF-α, IL-6, IL-1β, NO and the expression of iNOS by the LPS-primed macrophages. The effect was dose dependent and most significant at a dose level of 4.6 mg/kg b. wt. Taken together, the study concludes that boron at physiological concentration induces lymphocyte proliferation and increases the synthesis and secretion of pro-inflammatory mediators by the LPS-primed macrophages, more specifically the M1 macrophages, possibly acting through Toll-like receptor. The study implicates boron as a regulator of the immune and inflammatory reactions and macrophage polarization, thus playing an important role in augmenting host defense against infection, with possible role in cancer and other diseases.

  2. Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages.

    Science.gov (United States)

    Routray, Indusmita; Ali, Shakir

    2016-01-01

    Chemical mediators of inflammation (CMI) are important in host defense against infection. The reduced capacity of host to induce the secretion of these mediators following infection is one of the factors in host susceptibility to infection. Boron, which has been suggested for its role in infection, is reported in this study to increase lymphocyte proliferation and the secretion of CMI by the lipopolysaccharide (LPS)-stimulated peritoneal macrophages in BALB/c mice. Boron was administered to mice orally as borax at different doses for 10 consecutive days, followed by the stimulation of animals with ovalbumin and isolation of splenocytes for proliferation assay. The lymphocyte subsets were determined by flow cytometry in spleen cell suspension. The mediators of inflammation, TNF-α, IL-6, IL-1β and nitric oxide (NO), were measured in culture supernatant of LPS-primed macrophages isolated from borax treated mice. TNF and ILs were measured by ELISA. NO was determined by Griess test. The expression of inducible nitric oxide synthase (iNOS) in macrophages was studied by confocal microscopy. Results showed a significant increase in T and B cell populations, as indicated by an increase in CD4 and CD19, but not CD8, cells. Boron further stimulated the secretion of TNF-α, IL-6, IL-1β, NO and the expression of iNOS by the LPS-primed macrophages. The effect was dose dependent and most significant at a dose level of 4.6 mg/kg b. wt. Taken together, the study concludes that boron at physiological concentration induces lymphocyte proliferation and increases the synthesis and secretion of pro-inflammatory mediators by the LPS-primed macrophages, more specifically the M1 macrophages, possibly acting through Toll-like receptor. The study implicates boron as a regulator of the immune and inflammatory reactions and macrophage polarization, thus playing an important role in augmenting host defense against infection, with possible role in cancer and other diseases.

  3. Long-term exposures to low doses of silver nanoparticles enhanced in vitro malignant cell transformation in non-tumorigenic BEAS-2B cells.

    Science.gov (United States)

    Choo, Wun Hak; Park, Cho Hee; Jung, Shi Eun; Moon, Byeonghak; Ahn, Huiyeon; Ryu, Jung Seok; Kim, Keun-Soo; Lee, Yong Hwa; Yu, Il Je; Oh, Seung Min

    2016-12-01

    To predict carcinogenic potential of AgNPs on the respiratory system, BEAS-2B cells (human bronchial epithelial cells) were chronically exposed to low- and non-cytotoxic dose (0.13 and 1.33μg/ml) of AgNPs for 4months (#40 passages). To assess malignant cell transformation of chronic exposure to AgNPs, several bioassays including anchorage independent agar colony formation, cell migration/invasion assay, and epithelial-mesenchymal transition (EMT) were performed in BEAS-2B cells. Chronic exposure to AgNPs showed a significant increase of anchorage independent agar colony formation and cell migration/invasion. EMT, which is the loss of epithelial markers (E-Cadherin and Keratin) and the gain of mesenchymal marker (N-cadherin and Vimentin), was induced by chronic exposure to AgNPs. These responses indicated that chronic exposure to AgNPs could acquire characteristics of tumorigenic cells from normal BEAS-2B cells. In addition, caspase-3, p-p53, p-p38, and p-JNK were significantly decreased, while p-ERK1/2 was significantly increased. MMP-9 related to cell migration/invasion was upregulated, while a MMP-9 inhibitor, TIMP-1 was down-regulated. These results indicated that BEAS-2B cells exposed to AgNPs could induce anti-apoptotic response/anoikis resistance, and cell migration/invasion by complex regulation of MAPK kinase (p38, JNK, and ERK) and p53 signaling pathways. Therefore, we suggested that long-term exposure to low-dose of AgNPs could enhance malignant cell transformation in non-tumorigenic BEAS-2B cells. Our findings provide useful information needed to assess the carcinogenic potential of AgNPs.

  4. Autoionizing states of atomic boron

    Science.gov (United States)

    Argenti, Luca; Moccia, Roberto

    2016-04-01

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

  5. Combustion synthesis of novel boron carbide

    Science.gov (United States)

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

    2013-02-01

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

  6. Method of synthesizing cubic system boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Yuzu, S.; Sumiya, H.; Degawa, J.

    1987-10-13

    A method is described for synthetically growing cubic system boron nitride crystals by using boron nitride sources, solvents for dissolving the boron nitride sources, and seed crystals under conditions of ultra-high pressure and high temperature for maintaining the cubic system boron nitride stable. The method comprises the following steps: preparing a synthesizing vessel having at least two chambers, arrayed in order in the synthesizing vessel so as to be heated according to a temperature gradient; placing the solvents having different eutectic temperatures in each chamber with respect to the boron nitride sources according to the temperature gradient; placing the boron nitride source in contact with a portion of each of the solvents heated at a relatively higher temperature and placing at least a seed crystal in a portion of each of the solvents heated at a relatively lower temperature; and growing at least one cubic system boron nitride crystal in each of the solvents in the chambers by heating the synthesizing vessel for establishing the temperature gradient while maintaining conditions of ultra-high pressure and high temperature.

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

    Science.gov (United States)

    Rosenberg, David

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

  8. A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

    Science.gov (United States)

    Yang, Bin; Lv, Yin; Zhu, Jing-Yi; Han, Yun-Tao; Jia, Hui-Zhen; Chen, Wei-Hai; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2014-08-01

    The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly.

  9. High Kinetic Energy Penetrator Shielding and High Wear Resistance Materials Fabricated with Boron Nitride Nanotubes (BNNTS) and BNNT Polymer Composites

    Science.gov (United States)

    Kang, Jin Ho (Inventor); Park, Cheol (Inventor); Sauti, Godfrey (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert George (Inventor)

    2015-01-01

    Boron nitride nanotubes (BNNTs), boron nitride nanoparticles (BNNPs), carbon nanotubes (CNTs), graphites, or combinations, are incorporated into matrices of polymer, ceramic or metals. Fibers, yarns, and woven or nonwoven mats of BNNTs are used as toughening layers in penetration resistant materials to maximize energy absorption and/or high hardness layers to rebound or deform penetrators. They can be also used as reinforcing inclusions combining with other polymer matrices to create composite layers like typical reinforcing fibers such as Kevlar.RTM., Spectra.RTM., ceramics and metals. Enhanced wear resistance and usage time are achieved by adding boron nitride nanomaterials, increasing hardness and toughness. Such materials can be used in high temperature environments since the oxidation temperature of BNNTs exceeds 800.degree. C. in air. Boron nitride based composites are useful as strong structural materials for anti-micrometeorite layers for spacecraft and space suits, ultra strong tethers, protective gear, vehicles, helmets, shields and safety suits/helmets for industry.

  10. FTIR and electrical characterization of a-Si:H layers deposited by PECVD at different boron ratios

    Energy Technology Data Exchange (ETDEWEB)

    Orduna-Diaz, A., E-mail: abdu@susu.inaoep.mx [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro No. 1, Tonantzintla, Puebla 72840 (Mexico); Trevino-Palacios, C.G. [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro No. 1, Tonantzintla, Puebla 72840 (Mexico); Rojas-Lopez, M.; Delgado-Macuil, R.; Gayou, V.L. [Centro de Investigacion en Biotecnologia Aplicada (CIBA), IPN, Tlaxcala, Tlax. 72197 (Mexico); Torres-Jacome, A. [Instituto Nacional de Astrofisica, Optica y Electronica, Luis Enrique Erro No. 1, Tonantzintla, Puebla 72840 (Mexico)

    2010-10-25

    Hydrogenated amorphous silicon (a-Si:H) has found applications in flat panel displays, photovoltaic solar cell and recently has been employed in boron doped microbolometer array. We have performed electrical and structural characterizations of a-Si:H layers prepared by plasma enhanced chemical vapor deposition (PECVD) method at 540 K on glass substrates at different diborane (B{sub 2}H{sub 6}) flow ratios (500, 250, 150 and 50 sccm). Fourier transform infrared spectroscopy (FTIR) measurements obtained by specular reflectance sampling mode, show Si-Si, B-O, Si-H, and Si-O vibrational modes (611, 1300, 2100 and 1100 cm{sup -1} respectively) with different strengths which are associated to hydrogen and boron content. The current-voltage curves show that at 250 sccm flow of boron the material shows the lowest resistivity, but for the 150 sccm boron flow it is obtained the highest temperature coefficient of resistance (TCR).

  11. From Boron Cluster to Two-Dimensional Boron Sheet on Cu(111) Surface: Growth Mechanism and Hole Formation

    OpenAIRE

    Hongsheng Liu; Junfeng Gao; Jijun Zhao

    2013-01-01

    As attractive analogue of graphene, boron monolayers have been theoretically predicted. However, due to electron deficiency of boron atom, synthesizing boron monolayer is very challenging in experiments. Using first-principles calculations, we explore stability and growth mechanism of various boron sheets on Cu(111) substrate. The monotonic decrease of formation energy of boron cluster BN with increasing cluster size and low diffusion barrier for a single B atom on Cu(111) surface ensure cont...

  12. Developments in boron magnetic resonance imaging (MRI)

    Energy Technology Data Exchange (ETDEWEB)

    Schweizer, M.

    1995-11-01

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

  13. High-dose neutron detector project update

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-10

    These are the slides for a progress review meeting by the sponsor. This is an update on the high-dose neutron detector project. In summary, improvements in both boron coating and signal amplification have been achieved; improved boron coating materials and procedures have increase efficiency by ~ 30-40% without the corresponding increase in the detector plate area; low dead-time via thin cell design (~ 4 mm gas gaps) and fast amplifiers; prototype PDT 8” pod has been received and testing is in progress; significant improvements in efficiency and stability have been verified; use commercial PDT 10B design and fabrication to obtain a faster path from the research to practical high-dose neutron detector.

  14. High-dose neutron detector project update

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-10

    These are the slides for a progress review meeting by the sponsor. This is an update on the high-dose neutron detector project. In summary, improvements in both boron coating and signal amplification have been achieved; improved boron coating materials and procedures have increased efficiency by ~ 30-40% without the corresponding increase in the detector plate area; low dead-time via thin cell design (~ 4 mm gas gaps) and fast amplifiers; prototype PDT 8” pod has been received and testing is in progress; significant improvements in efficiency and stability have been verified; use commercial PDT 10B design and fabrication to obtain a faster path from the research to practical high-dose neutron detector.

  15. Nickel-boron electrochemical properties investigations

    Energy Technology Data Exchange (ETDEWEB)

    Kanta, A.-F., E-mail: abdoul.kanta@umons.ac.b [Service de Science des Materiaux, Universite de Mons, 56 rue de l' Epargne, 7000 Mons (Belgium); Poelman, M. [Materia Nova a.s.b.l, 56 rue de l' Epargne, 7000 Mons (Belgium); Vitry, V.; Delaunois, F. [Service de Metallurgie, Universite de Mons, 56 rue de l' Epargne, 7000 Mons (Belgium)

    2010-08-27

    Electroless nickel-boron (Ni-B) was synthesized on mild steel. Coating thickness was approximately 30 {mu}m. Some of the coatings were submitted to a hardening heat treatment at 400 {sup o}C for 1 h in an atmosphere containing 95% Ar and 5% H{sub 2} to improve their mechanical performance. Heat treated and untreated samples were submitted to the Taber abrasion test to assess their wear resistance. The wear track was then examined by SEM and roughness measurement. The Taber Wear Index of untreated samples was slightly better than that of steel but heat treated samples attained TWI as small as 13. The corrosion resistance of the Ni-B coatings was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The EIS results showed diffusion phenomena in 0.1 M NaCl solution. Electroless Ni-B coating increases the corrosion resistance of steel and heat treatments allow a further enhancement. Wear decreases that resistance but the worn product keeps a better behaviour than uncoated parts.

  16. Fabrication of boron-doped carbon fibers by the decomposition of B4C and its excellent rate performance as an anode material for lithium-ion batteries

    Science.gov (United States)

    Wang, Huiqi; Ma, Canliang; Yang, Xueteng; Han, Tao; Tao, Zechao; Song, Yan; Liu, Zhanjun; Guo, Quangui; Liu, Lang

    2015-03-01

    A facile route, for the first time, was developed to fabricate boron-doped carbon fibers (BDCFs). Boron was doped into mesosphere pitch-based carbon fibers (CFs) by exposing the CFs in a vapor of boron by the decomposition of boron carbide. The microstructure of BDCFs was characterized by SEM, TEM, XRD and Raman spectroscopy. When used as anode materials for the lithium-ion batteries, BDCFs electrode exhibits an improved performance. Concretely, the specific capacity of BDCFs still had a value of over 400 mAh g-1 after 100 cycles. Moreover, BDCFs exhibits better rate capability and less hysteresis in comparison to the pristine CFs. Such enhanced lithium storage capability can be attributed to the improvement of graphitization properties and the high amount of defects induced by boron.

  17. Bonding in boron: building high-pressure phases from boron sheets

    Energy Technology Data Exchange (ETDEWEB)

    Kunstmann, Jens [Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology (Germany); Boeri, Lilia [Max Planck Institute for Solid State Research, Stuttgart (Germany); Kortus, Jens [Institute for Theoretical Physics, TU Bergakademie Freiberg (Germany)

    2010-07-01

    We present the results of a study of the high pressure phase diagram of elemental boron, using full-potential density functional calculations. We show that at high pressures (P > 100 GPa) boron crystallizes in quasi-layered bulk phases, characterized by in-plane multicenter bonds and out-of-plane unidimensional sigma bonds. These structures are all metallic, in contrast to the low-pressure icosahedral ones, which are semiconducting. We show that the structure and bonding of layered bulk phases can be easily described in terms of single puckered boron sheets. Our results bridge the gap between boron nanostructures and bulk phases.

  18. 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.

  19. Prompt gamma-ray emission for future imaging applications in proton-boron fusion therapy

    Science.gov (United States)

    Petringa, G.; Cirrone, G. A. P.; Caliri, C.; Cuttone, G.; Giuffrida, L.; La Rosa, G.; Manna, R.; Manti, L.; Marchese, V.; Marchetta, C.; Margarone, D.; Milluzzo, G.; Picciotto, A.; Romano, F.; Romano, F. P.; Russo, A. D.; Russo, G.; Santonocito, D.; Scuderi, V.

    2017-03-01

    Recently, an approach exploiting the proton therapy biological enhancement by using Boron atoms injected inside a tumor, has been proposed [1-3]. Here, the 11B(p,α)2α nuclear fusion reaction channel, where three alpha particles are produced with an average energy around 4 MeV, is considered [4]. These alphas are able to penetrate the cells nucleus and strongly damage their DNA. In addition, gamma prompts emitted by the proton Boron nuclear reactions can be used for on-line proton beam imaging purposes. In this work an experimental study of the gamma prompt emissions from the proton Boron nuclear reactions has been carried out with the main aim to understand and quantify the most probable emission for future clinical applications.

  20. Growth and electrical characterisation of {delta}-doped boron layers on (111) diamond surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Edgington, Robert; Jackman, Richard B. [London Centre for Nanotechnology, and Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London, WC1H 0AH (United Kingdom); Sato, Syunsuke; Ishiyama, Yuichiro; Kawarada, Hiroshi [Department of Electronic and Photonic Systems, Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Morris, Richard [Advanced SIMS Projects, Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2012-02-01

    A plasma enhanced chemical vapor deposition protocol for the growth of {delta}-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated {delta}-layers and desirable sheet carrier densities ({approx}10{sup 13} cm{sup -2}) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cut-off frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 10{sup 20} cm{sup -3}.

  1. Laser-initiated primary and secondary nuclear reactions in Boron-Nitride

    Science.gov (United States)

    Labaune, C.; Baccou, C.; Yahia, V.; Neuville, C.; Rafelski, J.

    2016-02-01

    Nuclear reactions initiated by laser-accelerated particle beams are a promising new approach to many applications, from medical radioisotopes to aneutronic energy production. We present results demonstrating the occurrence of secondary nuclear reactions, initiated by the primary nuclear reaction products, using multicomponent targets composed of either natural boron (B) or natural boron nitride (BN). The primary proton-boron reaction (p + 11B → 3 α + 8.7 MeV), is one of the most attractive aneutronic fusion reaction. We report radioactive decay signatures in targets irradiated at the Elfie laser facility by laser-accelerated particle beams which we interpret as due to secondary reactions induced by alpha (α) particles produced in the primary reactions. Use of a second nanosecond laser beam, adequately synchronized with the short laser pulse to produce a plasma target, further enhanced the reaction rates. High rates and chains of reactions are essential for most applications.

  2. Boron nitride nanotubes for boron neutron capture therapy as contrast agents in magnetic resonance imaging at 3 T

    Energy Technology Data Exchange (ETDEWEB)

    Menichetti, L., E-mail: luca.menichetti@ifc.cnr.it [CNR-National Research Council of Italy, Institute of Clinical Physiology, via G. Moruzzi 1, 56124 Pisa (Italy); De Marchi, D. [Fondazione Toscana Gabriele Monasterio per la Ricerca Medica e la Sanita Pubblica, CNR-Regione Toscana, via Trieste 41, 56126 Pisa (Italy); Calucci, L. [CNR-National Research Council of Italy, ICCOM-Institute of OrganoMetallic Chemistry, via G. Moruzzi 1, 56124 Pisa (Italy); Ciofani, G.; Menciassi, A. [Italian Institute of Technology c/o Scuola Superiore Sant' Anna, viale R. Piaggio 34, 56025 Pontedera (Italy); Forte, C. [CNR-National Research Council of Italy, ICCOM-Institute of OrganoMetallic Chemistry, via G. Moruzzi 1, 56124 Pisa (Italy)

    2011-12-15

    The applicability of boron nitride nanotubes (BNNTs) containing Fe paramagnetic impurities as contrast agents in magnetic resonance imaging (MRI) was investigated. The measurement of longitudinal and transverse relaxation times of water protons in homogeneous aqueous dispersions of BNNTs wrapped with poly(L-lysine) at different concentrations allowed longitudinal (r{sub 1}) and transverse (r{sub 2}) relaxivities to be determined at 3 T. The r{sub 2} value was comparable to those of commercial superparamagnetic iron oxide nanoparticles, indicating that Fe-containing BNNTs have the potential to be used as T{sub 2} contrast-enhancement agents in MRI at 3 T.

  3. 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.

  4. Response of Boron and Light on Morph-Physiology and Pod Yield of Two Peanut Varieties

    Directory of Open Access Journals (Sweden)

    Md. Quamruzzaman

    2016-01-01

    Full Text Available Boron is an important micronutrient that enhances vegetative growth and yield of crops, like peanut. Light also plays an important role in pegging of peanut. There has been little information regarding the application of boron and light in peanut in Bangladesh. Therefore, a field experiment was conducted to study the response of boron and light on morph-physiology and pod yield of two peanut varieties. Treatments considered two peanut varieties, namely, Dhaka-1 and BARI Chinabadam-8, three levels of boron (B, namely, 0-kg B ha−1 (B0, 1-kg B ha−1 (B1, and 2-kg B ha−1 (B2, and two levels of light, namely, normal day light (≈12 h light and normal day light + 6 h extended red light at night (≈18 h light. Result revealed that days to first-last emergence and days to first-50% flowering took shorter times and vegetative growth, pods dry weight plant−1, pod yield, and germination were markedly increased with the application of boron. Vegetative growth and germinations were significantly increased in light, but the lowest leaf area, pods dry weight plant−1, and pod yield were found in light. Without germination, the highest vegetative growth, reproductive unit, and pod yield were observed from BARI Chinabadam-8. Days to first-last emergence, days to first-50% flowering, and number of branches plant−1 were found linearly related to pod yield.

  5. Reproductive toxicity parameters and biological monitoring in occupationally and environmentally boron-exposed persons in Bandirma, Turkey.

    Science.gov (United States)

    Duydu, Yalçın; Başaran, Nurşen; Üstündağ, Aylin; Aydin, Sevtap; Ündeğer, Ülkü; Ataman, Osman Yavuz; Aydos, Kaan; Düker, Yalçın; Ickstadt, Katja; Waltrup, Britta Schulze; Golka, Klaus; Bolt, Hermann M

    2011-06-01

    Boric acid and sodium borates have been considered as being "toxic to reproduction and development", following results of animal studies with high doses. Experimentally, a NOAEL (no observed adverse effect level) of 17.5 mg B/kg-bw/day has been identified for the (male) reproductive effects of boron in a multigeneration study of rats, and a NOAEL for the developmental effects in rats was identified at 9.6 mg B/kg-bw/day. These values are being taken as the basis of current EU safety assessments. The present study was conducted to investigate the reproductive effects of boron exposure in workers employed in boric acid production plant in Bandirma, Turkey. In order to characterize the external and internal boron exposures, boron was determined in biological samples (blood, urine, semen), in workplace air, in food, and in water sources. Unfavorable effects of boron exposure on the reproductive toxicity indicators (concentration, motility, morphology of the sperm cells and blood levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and total testosterone) were not observed. The mean calculated daily boron exposure (DBE) of the highly exposed group was 14.45 ± 6.57 (3.32-35.62) mg/day. These human exposures represent worst-case exposure conditions to boric acid/borates in Turkey. These exposure levels are considerably lower than exposures, which have previously led to reproductive effects in experimental animals. In conclusion, this means that dose levels of boron associated with developmental and reproductive toxic effects in animals are by far not reachable for humans under conditions of normal handling and use.

  6. Effect of boron ion implantation on the structural, optical and electrical properties of ZnSe thin films

    Science.gov (United States)

    Venkatachalam, S.; Kanno, Yoshinori; Mangalaraj, D.; Narayandass, Sa. K.

    2007-03-01

    Zinc Selenide (ZnSe) thin films were deposited onto well cleaned glass substrates using vacuum evaporation technique under a vacuum of 3×10 -5 mbar. The prepared ZnSe samples were implanted with mass analyzed 75 keV B + ions at different doses ranging from 10 12 to 10 16 ions cm -2. The composition, thickness, microstructures, surface roughness and optical band gap of the as-deposited and boron-implanted films were studied by Rutherford backscattering (RBS), grazing incidence X-ray diffraction, Atomic force microscopy, Raman scattering and transmittance measurements. The RBS analysis indicates that the composition of the as-deposited and boron-implanted films is nearly stoichiometric. The thickness of the as-deposited film is calculated as 230 nm. The structure of the as-deposited and boron-implanted thin films is cubic. It is found that the surface roughness increases on increasing the dose of boron ions. In the optical studies, the optical band gap value decreases with an increase of boron concentration. In the electrical studies, the prepared device gave a very good response in the blue wavelength region.

  7. Boron-Based (Nano-Materials: Fundamentals and Applications

    Directory of Open Access Journals (Sweden)

    Umit B. Demirci

    2016-09-01

    Full Text Available The boron (Z = 5 element is unique. Boron-based (nano-materials are equally unique. Accordingly, the present special issue is dedicated to crystalline boron-based (nano-materials and gathers a series of nine review and research articles dealing with different boron-based compounds. Boranes, borohydrides, polyhedral boranes and carboranes, boronate anions/ligands, boron nitride (hexagonal structure, and elemental boron are considered. Importantly, large sections are dedicated to fundamentals, with a special focus on crystal structures. The application potentials are widely discussed on the basis of the materials’ physical and chemical properties. It stands out that crystalline boron-based (nano-materials have many technological opportunities in fields such as energy storage, gas sorption (depollution, medicine, and optical and electronic devices. The present special issue is further evidence of the wealth of boron science, especially in terms of crystalline (nano-materials.

  8. Microstructure and superconducting properties of nanocarbon-doped internal Mg diffusion-processed MgB2 wires fabricated using different boron powders

    Science.gov (United States)

    Xu, Da; Wang, Dongliang; Li, Chen; Yuan, Pusheng; Zhang, Xianping; Yao, Chao; Dong, Chiheng; Huang, He; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-04-01

    MgB2/Nb/Monel monofilament wires were fabricated using four different boron powders by an internal Mg diffusion (IMD) process. The microstructure, morphology and the critical current density (J c) of the used boron powders and the formative MgB2 layers were analyzed and compared. It was found that the purity and particle size of the boron powder influence the superconducting properties of MgB2 wires; further that the optimized heat-treatment condition also depends on the quality of the boron powder. The highest J c was obtained in the MgB2 layer made using amorphous boron (AB) powder, although a certain amount of voids existed in the superconducting layer. The IMD-processed MgB2 layer fabricated using high-purity boron (HB) powder had also a high J c compared with the powder-in-tube (PIT) process and a few unreacted boron particles remained in it. MgB2 wire fabricated using low-purity boron (LB) powder had a high cost-performance ratio compared with the others, which is expected to allow the fabrication of large-scale and low-cost superconducting wires for practical application. However, the enhancement of the J c was not found in the MgB2 layer manufactured using the ball-milled LB (MLB) powder as expected due to the increased percentage of impurity.

  9. Catalytic Asymmetric Synthesis of Phosphine Boronates

    NARCIS (Netherlands)

    Hornillos, Valentin; Vila, Carlos; Otten, Edwin; Feringa, Ben L.

    2015-01-01

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of ,-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good y

  10. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

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

    2016-07-01

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

  11. Boron-10 loaded inorganic shielding material

    Science.gov (United States)

    Baker, S. I.; Ryskiewicz, R. S.

    1972-01-01

    Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.

  12. Spectromicroscopy in Boron Neutron Capture Therapy Research

    Science.gov (United States)

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

    1998-03-01

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

  13. Boron-Filled Hybrid Carbon Nanotubes

    Science.gov (United States)

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

    2016-01-01

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

  14. Combustion Behavior of Free Boron Slurry Droplets,

    Science.gov (United States)

    2014-09-26

    weak disruptive behavior while pure JP-1t burn quiescently, except for a flash extinction which occurs at the termination of combustion. The...I AD-R158 628 COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS(U) i/i I PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENINEERIN., F TAKAHASHI...COMBUSTION BEHAVIOR OF FREE BORON SLURRY DROPLETS TAM by F. Takahashi, F.L. Dryer, and F.A. Williams Department of M~echanical and keyosase Engineering

  15. Characterization of device isolation in GaAs MESFET circuits by boron implantation

    Energy Technology Data Exchange (ETDEWEB)

    Clauwaert, F.; Van Daele, P.; Lagasse, P.

    1987-03-01

    The use of boron implantation for the electrical isolation of MESFET's and other electronic components in GaAs high speed digital IC's has been investigated. The sheet isolation resistance was measured as a function of the implantation energy and dose and of the anneal temperature and time. Topics considered include fabrication, integrated circuits, electric conductivity, annealing, transistors, ion implantation, and digital systems.

  16. Can epithermal boron neutron capture therapy treat primary and metastatic liver cancer?

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, S.A. [Austin Repatriation Medical Centre, Heidelberg (Australia); Carolan, M.C. [Illawarra Cancer Care Centre, Wollongong (Australia); Allen, B.J. [St George Cancer Care Centre, Kogarah (Australia)

    1996-12-31

    Full text: The poor prognosis of metastatic cancer to the liver calls for the investigation of alternative treatment modalities. This paper analyses the possible use of epithermal boron neutron capture therapy for the palliative treatment of these cancers. We examine possible treatment planning scenarios for selected tumour to liver boron ratios, and specifically for the epithermal beam at the HFR, Petten. It is required that a therapeutic ratio> 1 be achieved over the entire organ. Monte Carlo calculations were performed using the radiation transport code MCNP. The geometrical model used a `variable voxel` technique to reconstruct an anthropomorphic phantom from CT scans. Regions of interest such as the liver were modelled to a resolution of a few millimetres, whereas surrounding regions were modelled with lesser detail thereby facilitating faster computation time. Three dimensional dose distributions were calculated for a frontal beam directed at the liver, and found to be in satisfactory agreement with measurements using bare and cadmium covered gold foils, PIN and MOSFET dosimeters for fast neutron and gamma measurements respectively. Dose distributions were calculated for orthogonal epithermal neutron beams to the front and side, using the parameters of the epithermal beam at Petten, and assumed tumour and normal tissue boron-10 concentrations of 30 ppm and 7.5 ppm boron-10 respectively. The therapeutic ratio (i e the dose to the tumour relative to the maximum dose to normal tissue) was found to be about 1.8, reducing to unity for the limiting condition of a tumour in the posterior liver. This result opens up the possibility of palliative therapy for the management of primary and metastatic liver cancer.

  17. The radiobiological principles of boron neutron capture therapy: A critical review

    Energy Technology Data Exchange (ETDEWEB)

    Hopewell, J.W., E-mail: john.hopewell@gtc.ox.ac.uk [Green Templeton College and Particle Therapy Cancer Research Institute, University of Oxford, Oxford (United Kingdom); Morris, G.M. [Medical Department, Brookhaven National Laboratory, Upton, NY (United States); Schwint, A. [Department of Radiobiology, Constituyentes Atomic Center, National Atomic Energy Commission, San Martin, Buenos Aires (Argentina); Coderre, J.A. [Ora Inc, 300 Brickstone Square, Andover, MA (United States)

    2011-12-15

    The radiobiology of the dose components in a BNCT exposure is examined. The effect of exposure time in determining the biological effectiveness of {gamma}-rays, due to the repair of sublethal damage, has been largely overlooked in the application of BNCT. Recoil protons from fast neutrons vary in their relative biological effectiveness (RBE) as a function of energy and tissue endpoint. Thus the energy spectrum of a beam will influence the RBE of this dose component. Protons from the neutron capture reaction in nitrogen have not been studied but in practice protons from nitrogen capture have been combined with the recoil proton contribution into a total proton dose. The relative biological effectiveness of the products of the neutron capture reaction in boron is derived from two factors, the RBE of the short range particles and the bio-distribution of boron, referred to collectively as the compound biological effectiveness factor. Caution is needed in the application of these factors for different normal tissues and tumors. - Highlights: Black-Right-Pointing-Pointer Radiobiological properties of different dose components in BNCT are considered. Black-Right-Pointing-Pointer Effectiveness of {gamma}-ray dose depends strongly on exposure time due to sublethal damage repair. Black-Right-Pointing-Pointer Effectiveness of fast neutron dose depends on neutron energy spectrum. Black-Right-Pointing-Pointer {gamma}-ray and fast neutron characteristics vary between beams and thus weighting factors will differ. Black-Right-Pointing-Pointer Weighing factors for boron dose depend on the carrier, the tissue and its mode of administration.

  18. Innovative boron nitride-doped propellants

    Institute of Scientific and Technical Information of China (English)

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

    2016-01-01

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

  19. 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.

  20. Enhancement of N-nitrosodiethylamine-initiated hepatocarcinogenesis by phentoin in male F344/NCr rats at a dose causing maximal induction of CYP2B.

    Science.gov (United States)

    Diwan, B A; Henneman, J R; Nims, R W

    2001-01-01

    The effect of the clinically important anticonvulsant phenytoin (DPH) on hepatocarcinogenesis of male F344/NCr rats initiated with a single i.p. dose of N-nitrosodiethylamine (75 mg/kg b.w.) was studied. Beginning 2 weeks post-initiation, the rats received control diet or diet containing 500 or 1,500 ppm DPH or 500 ppm phenobarbital. At 52 weeks age, the incidences (and multiplicities, in units of tumors per tumor-bearing rat) of hepatocellular adenomas were 0%, 17% (1 +/- 0), 42% (1.8 +/- 0.8), or 67% (2.5 +/- 1.9) in rats exposed to N-nitrosodiethylamine alone, or the carcinogen followed by 500 ppm DPH, 1,500 ppm DPH, or 500 ppm phenobarbital, respectively. Between 53 and 79 weeks of age, 39% of rats receiving N-nitrosodiethylamine alone developed multiple (1.5 +/- 0.8) hepatocellular adenomas. A similar incidence (41%) occurred in the rats administered the carcinogen followed by 500 ppm DPH. The incidence of hepatocellular adenomas (88% and 89%) was significantly greater in rats exposed to N-nitrosodiethylamine followed by 1,500 ppm DPH or 500 ppm phenobarbital, respectively. Multiplicities of hepatocellular adenomas were significantly greater than the control value in rats fed 1,500 ppm DPH or 500 ppm phenobarbital (5.9 +/- 4.8 and 10.1 +/- 6.7, respectively), but not in the rats receiving 500 ppm DPH (2.3 +/- 1.6). No rats exposed to N-nitrosodiethylamine alone or the carcinogen followed by 500 ppm DPH developed hepatocellular carcinomas, while hepatocellular carcinomas occurred in 29% or 67% of the rats given 1,500 ppm DPH or 500 ppm phenobarbital, respectively, following initiation. Increases in hepatic CYP2B-mediated benzyloxyresorufin O-dealkylation activity in rats exposed to 500 and 1,500 ppm DPH for 2 or 23 weeks were approximately 50% and approximately 100%, respectively, of the maximal induction caused by 500 ppm phenobarbital. Thus, in the rat model, DPH enhanced N-nitrosodiethyl-amine-initiated hepatocarcinogenesis when administered at a dose

  1. Boronophenylalanine, a boron delivery agent for boron neutron capture therapy, is transported by ATB0,+, LAT1 and LAT2.

    Science.gov (United States)

    Wongthai, Printip; Hagiwara, Kohei; Miyoshi, Yurika; Wiriyasermkul, Pattama; Wei, Ling; Ohgaki, Ryuichi; Kato, Itsuro; Hamase, Kenji; Nagamori, Shushi; Kanai, Yoshikatsu

    2015-03-01

    The efficacy of boron neutron capture therapy relies on the selective delivery of boron carriers to malignant cells. p-Boronophenylalanine (BPA), a boron delivery agent, has been proposed to be localized to cells through transporter-mediated mechanisms. In this study, we screened aromatic amino acid transporters to identify BPA transporters. Human aromatic amino acid transporters were functionally expressed in Xenopus oocytes and examined for BPA uptake and kinetic parameters. The roles of the transporters in BPA uptake were characterized in cancer cell lines. For the quantitative assessment of BPA uptake, HPLC was used throughout the study. Among aromatic amino acid transporters, ATB(0,+), LAT1 and LAT2 were found to transport BPA with Km values of 137.4 ± 11.7, 20.3 ± 0.8 and 88.3 ± 5.6 μM, respectively. Uptake experiments in cancer cell lines revealed that the LAT1 protein amount was the major determinant of BPA uptake at 100 μM, whereas the contribution of ATB(0,+) became significant at 1000 μM, accounting for 20-25% of the total BPA uptake in MCF-7 breast cancer cells. ATB(0,+), LAT1 and LAT2 transport BPA at affinities comparable with their endogenous substrates, suggesting that they could mediate effective BPA uptake in vivo. The high and low affinities of LAT1 and ATB(0,+), respectively, differentiate their roles in BPA uptake. ATB(0,+), as well as LAT1, could contribute significantly to the tumor accumulation of BPA at clinical dose.

  2. Complementary incorporation of boron compounds with different cellular targets in melanoma

    Energy Technology Data Exchange (ETDEWEB)

    Morre, D.E. [University of Sydney, Dept. of Pharmacy, Sydney, NSW (Australia); Setiawan, Y.; Allen, B.J. [St George Cancer Care Centre, Kogarah, NSW (Australia)

    1996-12-31

    Full text. The heterogeneity of malignant tumours is well known, and post-surgical control may only be achieved by the application of a number of adjuvant therapies. In boron neutron capture therapy (BNCT), a similar effect could be achieved by utilising boron compounds with quite different uptake and incorporation mechanisms. While tumour growth delay or control can be induced by BNCT in animal models, long term control in human patients may be much more difficult. Thus we have carried out experiments with two boron compounds which exhibit quite different pharmacokinetics and interact with cancer cells by quite different mechanisms. The compounds studied were p-boronophenylalanine (BPA) and boronated low density lipoprotein (B-LDL). Non-specific boron compounds such as n-alkyl carboranes can be delivered to melanoma tumour cells when incorporated in reconstituted LDL. Biodistribution studies were performed with BALB/c mice bearing subcutaneous Harding-Passey melanoma xenografts. The mice were pretreated with a high fat diet and hydrocortisone to down regulate the non-autonomous LDL receptors. A tumour to blood boron concentration ratio of 5:1 was achieved 18 hours after administration of B-LDL. The same compound administered in a non-specific arachis oil vehicle failed to demonstrate selective uptake in the tumour. Neutron capture therapy using B-LDL as the boron delivery vehicle produced a growth delay effect on the tumours which was equivalent to that found when BPA was administered as the fructose complex to develop a similar boron concentration in the tumour. This is indicative that the boron microdistribution across different types of tumour cells achieved by B-LDL has a similar effect to that achieved by BPA in the tumour model, even though the uptake mechanisms for BPA and B-LDL are different. BPA uptake is thought to be dependent on the amino acid transport mechanism, whereas receptor density determines LDL incorporation. Thus the combined administration

  3. Boron neutron capture therapy (BNCT) for the treatment of spontaneous nasal planum squamous cell carcinoma in felines.

    Science.gov (United States)

    Trivillin, Verónica A; Heber, Elisa M; Rao, Monica; Cantarelli, María A; Itoiz, Maria E; Nigg, David W; Calzetta, Osvaldo; Blaumann, Herman; Longhino, Juan; Schwint, Amanda E

    2008-02-01

    Recently, Boron neutron capture therapy (BNCT) was successfully applied to treat experimental squamous cell carcinomas (SCC) of the hamster cheek pouch mucosa, with no damage to normal tissue. It was also shown that treating spontaneous nasal planum SCC in terminal feline patients with low dose BNCT is safe and feasible. In an extension of this work, the present study aimed at evaluation of the response of tumor and dose-limiting normal tissues to potentially therapeutic BNCT doses. Biodistribution studies with (10)B-boronophenylalanine (BPA enriched in (10)B) as a (10)B carrier were performed on three felines that showed advanced nasal planum SCC without any standard therapeutic option. Following the biodistribution studies, BNCT mediated by (10)BPA was done using the thermalized epithermal neutron beam at the RA-6 Nuclear Reactor. Follow-up included clinical evaluation, assessment of macroscopic tumor and normal tissue response and biopsies for histopathological analysis. The treated animals did not show any apparent radiation-induced toxicity. All three animals exhibited partial tumor control and an improvement in clinical condition. Enhanced therapeutic efficacy was associated with a high (10)B content of the tumor and a small tumor size. BNCT is therefore believed to be potentially effective in the treatment of spontaneous SCC. However, improvement in targeting (10)B into all tumor cells and delivering a sufficient dose at a greater depth are still required for the treatment of deep-seated, large tumors. Future studies are needed to evaluate the potential efficacy of the dual mode cellular (e.g. BPA-BNCT) and vascular (e.g. GB-10-BNCT) targeting protocol in a preclinical scenario, employing combinations of (10)B compounds with different properties and complementary uptake mechanisms.

  4. Electron spin relaxation of a boron-containing heterocyclic radical

    Science.gov (United States)

    Eaton, Sandra S.; Huber, Kirby; Elajaili, Hanan; McPeak, Joseph; Eaton, Gareth R.; Longobardi, Lauren E.; Stephan, Douglas W.

    2017-03-01

    Preparation of the stable boron-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), by frustrated Lewis pair chemistry has been reported recently. Electron paramagnetic resonance measurements of this radical were made at X-band in toluene:dichloromethane (9:1) from 10 to 293 K, in toluene from 180 to 293 K and at Q-band at 80 K. In well-deoxygenated 0.1 mM toluene solution at room temperature hyperfine splittings from 11B, four pairs of 1H, and 5 pairs of 19F contribute to an EPR spectrum with many resolved lines. Observed hyperfine couplings were assigned based on DFT calculations and account for all of the fluorines and protons in the molecule. Rigid lattice g values are gx = 2.0053, gy = 2.0044, and gz = 2.0028. Near the melting point of the solvent 1/Tm is enhanced due to motional averaging of g and A anisotropy. Increasing motion above the melting point enhances 1/T1 due to contributions from tumbling-dependent processes. The overall temperature dependence of 1/T1 from 10 to 293 K was modeled with the sum of contributions of a process that is linear in T, a Raman process, spin rotation, and modulation of g anisotropy by molecular tumbling. The EPR measurements are consistent with the description of this compound as a substituted aromatic radical, with relatively small spin density on the boron.

  5. 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.)

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

    Science.gov (United States)

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

  7. Junctions between a boron nitride nanotube and a boron nitride sheet.

    Science.gov (United States)

    Baowan, Duangkamon; Cox, Barry J; Hill, James M

    2008-02-20

    For future nanoelectromechanical signalling devices, it is vital to understand how to connect various nanostructures. Since boron nitride nanostructures are believed to be good electronic materials, in this paper we elucidate the classification of defect geometries for combining boron nitride structures. Specifically, we determine possible joining structures between a boron nitride nanotube and a flat sheet of hexagonal boron nitride. Firstly, we determine the appropriate defect configurations on which the tube can be connected, given that the energetically favourable rings for boron nitride structures are rings with an even number of sides. A new formula E = 6+2J relating the number of edges E and the number of joining positions J is established for each defect, and the number of possible distinct defects is related to the so-called necklace and bracelet problems of combinatorial theory. Two least squares approaches, which involve variation in bond length and variation in bond angle, are employed to determine the perpendicular connection of both zigzag and armchair boron nitride nanotubes with a boron nitride sheet. Here, three boron nitride tubes, which are (3, 3), (6, 0) and (9, 0) tubes, are joined with the sheet, and Euler's theorem is used to verify geometrically that the connected structures are sound, and their relationship with the bonded potential energy function approach is discussed. For zigzag tubes (n,0), it is proved that such connections investigated here are possible only for n divisible by 3.

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

    Science.gov (United States)

    Gilbert, B.; Redondo, J.; Baudat, P.-A.; Lorusso, G. F.; Andres, R.; Van Meir, E. G.; Brunet, J.-F.; Hamou, M.-F.; Suda, T.; Mercanti, Delio; Ciotti, M. Teresa; Droubay, T. C.; Tonner, B. P.; Perfetti, P.; Margaritondo, M.; DeStasio, Gelsomina

    1998-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, B.; Redondo, J.; Baudat, P-A. [Institut de Physique Appliquee, Ecole Polytechnique Federale, Lausanne (Switzerland)] [and others

    1998-10-07

    We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of {sup 10}B in tumour cells after injection of a boron compound (in our case B{sub 12}H{sub 11}SH, or BSH). With the Mephisto (microscope a emission de photoelectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy. (author)

  10. 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.

  11. DABO Boronates: Stable Heterocyclic Boronic Acid Complexes for Use in Suzuki-Miyaura Cross-Coupling Reactions.

    Science.gov (United States)

    Reilly, Maureen K; Rychnovsky, Scott D

    2011-10-01

    Diethanolamine complexed heterocyclic boronic acids (DABO boronates) are air-stable reagents that can be used directly in Suzuki-Miyaura reactions in the presence of water or a protic co-solvent. Interestingly, heterocyclic DABO boronates can be stored for extended periods of time at room temperature with no noticeable degradation, unlike their boronic acid counterparts. Heterocyclic DABO boronates constitute an operationally simple and efficient alternative to other boronic acid derivatives as coupling partners in palladium catalyzed cross-coupling reactions under standard Suzuki-Miyaura conditions.

  12. Dynamic contrast-enhanced magnetic resonance imaging of osseous spine metastasis before and 1 hour after high-dose image-guided radiation therapy.

    Science.gov (United States)

    Lis, Eric; Saha, Atin; Peck, Kyung K; Zatcky, Joan; Zelefsky, Michael J; Yamada, Yoshiya; Holodny, Andrei I; Bilsky, Mark H; Karimi, Sasan

    2017-01-01

    OBJECTIVE High-dose image-guided radiation therapy (HD IGRT) has been instrumental in mitigating some limitations of conventional RT. The recent emergence of dynamic contrast-enhanced (DCE) MRI to investigate tumor physiology can be used to verify the response of human tumors to HD IGRT. The purpose of this study was to evaluate the near-immediate effects of HD IGRT on spine metastases through the use of DCE MRI perfusion studies. METHODS Six patients with spine metastases from prostate, thyroid, and renal cell carcinoma who underwent HD IGRT were studied using DCE MRI prior to and 1 hour after HD IGRT. The DCE perfusion parameters plasma volume (Vp) and vascular permeability (Ktrans) were measured to assess the near-immediate and long-term tumor response. A Mann-Whitney U-test was performed to compare significant changes (at p ≤ 0.05) in perfusion parameters before and after RT. RESULTS The authors observed a precipitous drop in Vp within 1 hour of HD IGRT, with a mean decrease of 65.2%. A significant difference was found between Vp values for before and 1 hour after RT (p ≤ 0.05). No significant change was seen in Vp (p = 0.31) and Ktrans (p = 0.1) from 1 hour after RT to the first follow-up. CONCLUSIONS The data suggest that there is an immediate effect of HD IGRT on the vascularity of spine metastases, as demonstrated by a precipitous decrease in Vp. The DCE MRI studies can detect such changes within 1 hour after RT, and findings are concordant with existing animal models.

  13. Continuous infusion of the α7 nicotinic acetylcholine receptor agonist EVP-6124 produces no signs of tolerance at memory-enhancing doses in rats: a pharmacokinetic and behavioral study.

    Science.gov (United States)

    van Goethem, Nick P; Prickaerts, Jos; Welty, Devin; Flood, Dorothy G; Koenig, Gerhard

    2015-06-01

    We investigated whether the effects of acutely administered EVP-6124, an α7 nicotinic acetylcholine receptor (α7 nAChR) agonist, on cognition were maintained after 6-day continuous minipump administration. Performance in a delay-dependent forgetting test was measured in the object recognition task after single-oral doses of 0.3 or 1 mg/kg, or at plasma steady-state concentrations (Css) of 0.6 or 2 ng/ml, which were similar to the efficacious plasma concentrations after single-oral dosing. The 0.3 mg/kg acute dose enhanced memory at a total plasma concentration of ∼0.3 ng/ml at 1-4 h after dosing. Continuous treatment produced total plasma Css values of 0.48 and 1.93 ng/ml on day 6 and enhanced memory. At EVP-6124 plasma concentrations that optimally enhance memory in the object recognition task, tolerance did not develop after 6 days of continuous treatment.

  14. REMOVAL OF BORON USING CLAY-EFFECT OF PROCESS PARAMETERS,KINETIC AND ISOTHERM STUDIES

    Directory of Open Access Journals (Sweden)

    N. RAJAMOHAN

    2016-03-01

    Full Text Available In this study, a low-cost eco-friendly adsorbent was prepared from naturally available sarooj clay and is proposed for the removal of boron from aqueous phase. The effect of process parameters, namely initial pH, sorbent quantity, initial boron concentration, shaking speed and temperature were studied on the metal uptake under batch conditions. The process efficiency was observed to be strongly parameter dependent and the optimal pH was found to be 10.0.The uptake capacity decreased with increase in sorbent dose and increased with boron concentration. Temperature was found to have a positive influence confirming the endothermic nature of the process. Equilibrium sorption data were analysed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm and represented well by Freundlich isotherm. The Freundlich constant was evaluated as 14.791 L g-1 at 35 °C.The mechanism of sorption was investigated using kinetic models, namely, pseudo-second order and intraparticle diffusion models .The batch experimental fitted well to pseudo-second order model and the rate constant was found to be 0.0017 g mg-1min-1 with an initial boron concentration of 100 mg L-1. The sorbent characteristics were studied using X-ray diffraction, scanning electron microscope with energy dispersive X-ray detector and X-ray fluorescence methods.

  15. A feasibility study evaluating the relationship between dose and focal liver reaction in stereotactic ablative radiotherapy for liver cancer based on intensity change of Gd-EOB-DTPA-enhanced magnetic resonance images

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sang Hoon; Yu, Jeong Il; Park, Hee Chul; Lim, Do Hoon; Han, Young Yih [Dept. of Radiation Oncology, amsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2016-03-15

    In order to evaluate the relationship between the dose to the liver parenchyma and focal liver reaction (FLR) after stereotactic ablative body radiotherapy (SABR), we suggest a novel method using a three-dimensional dose distribution and change in signal intensity of gadoxetate disodium-gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) hepatobiliary phase images. In our method, change of the signal intensity between the pretreatment and follow-up hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was calculated and then threshold dose (TD) for developing FLR was obtained from correlation of dose with the change of the signal intensity. For validation of the method, TDs for six patients, who had been treated for liver cancer with SABR with 45-60 Gy in 3 fractions, were calculated using the method, and we evaluated concordance between volume enclosed by isodose of TD by the method and volume identified as FLR by a physician. The dose to normal liver was correlated with change in signal intensity between pretreatment and follow-up MRI with a median R{sup 2} of 0.935 (range, 0.748 to 0.985). The median TD by the method was 23.5 Gy (range, 18.3 to 39.4 Gy). The median value of concordance was 84.5% (range, 44.7% to 95.9%). Our method is capable of providing a quantitative evaluation of the relationship between dose and intensity changes on follow-up MRI, as well as determining individual TD for developing FLR. We expect our method to provide better information about the individual relationship between dose and FLR in radiotherapy for liver cancer.

  16. Structures of Pt clusters on graphene doped with nitrogen, boron, and silicon: a theoretical study

    Institute of Scientific and Technical Information of China (English)

    Dai Xian-Qi; Tang Ya-Nan; Dai Ya-Wei; Li Yan-Hui; Zhao Jian-Hua; Zhao Bao; Yang Zong-Xian

    2011-01-01

    The structures of Pt clusters on nitrogen-, boron-, silicon- doped graphenes are theoretically studied using densityfunctional theory. These dopants (nitrogen, boron and silicon) each do not induce a local curvature in the graphene and the doped graphenes all retain their planar form. The formation energy of the silicon-graphene system is lower than those of the nitrogen-, boron-doped graphenes, indicating that the silicon atom is easier to incorporate into the graphene.All the substitutional impurities enhance the interaction between the Pt atom and the graphene. The adsorption energy of a Pt adsorbed on the silicon-doped graphene is much higher than those on the nitrogen- and boron-doped graphenes.The doped silicon atom can provide more charges to enhance the Pt-graphene interaction and the formation of Pt clusters each with a large size. The stable structures of Pt clusters on the doped-graphenes are dimeric, triangle and tetrahedron with the increase of the Pt coverage. Of all the studied structures, the tetrahedron is the most stable cluster which has the least influence on the planar surface of doped-graphene.

  17. Enhancement of viability of radiosensitive (PBMC) and resistant (MDA-MB-231) clones in low-dose-rate cobalt-60 radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, Patricia Lima, E-mail: patricialfalcao@gmail.com [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil); Motta, Barbara Miranda; Lima, Fernanda Castro de; Lima, Celso Vieira; Campos, Tarcisio Passos Ribeiro [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2015-05-15

    Objective: in the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231) cells line and radiosensitive peripheral blood mononuclear cells (PBMC), as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and methods: the cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min{sup -1} and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB-231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48-72 hours post-radiation. Conclusion: low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer. (author)

  18. Enhancement of viability of radiosensitive (PBMC and resistant (MDA-MB-231 clones in low-dose-rate cobalt-60 radiation therapy

    Directory of Open Access Journals (Sweden)

    Patrícia Lima Falcão

    2015-06-01

    Full Text Available Abstract Objective: In the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231 cells line and radiosensitive peripheral blood mononuclear cells (PBMC, as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and Methods: The cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min–1 and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: Radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB- 231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48–72 hours post-radiation. Conclusion: Low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer.

  19. Depth-Dose and LET Distributions of Antiproton Beams in Various Target Materials

    DEFF Research Database (Denmark)

    Herrmann, Rochus; Olsen, Sune; Petersen, Jørgen B.B.;

    unrestricted LET is calculated for all configurations. Finally, we investigate which concentrations of gadolinium and boron are needed in a water target in order to observe a significant change in the antiproton depth-dose distribution.  Results Results indicate, that there is no significant change...... in the depth-dose distribution and average LET when substituting the materials. Adding boron and gadolinium up to concentrations of 1 per 1000 atoms to a water phantom, did not change the depth-dose profile nor the average LET. Conclusions  According to our FLUKA calculations, antiproton neutron capture...

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

    Directory of Open Access Journals (Sweden)

    LI Jian-ping

    2014-02-01

    Full Text Available The boron isotopes separation test was performed by chemical exchange reaction in the benzene ether -three boron fluoride system, which resulted to the boron isotopic enrichment of -10 in the liquid phase, the boron isotopic enrichment of -11 in the gas phase. After then, boron isotope separation trial production has been finished. In this process, the exchange column and complex tower normal operating parameters and the complex tower technology have been obtained, the problems of material distillation purification is solved, boron isotopes feasibility with PTFE packing enrichment is verified in an exchange column. Also, effect of operating pressure, flow and other parameters on boron -10 isotopic enrichment experiments and the effect and properties of the PTFE packing have been investigated in the existing system. All the results are very useful for the industrialization of the boron isotopes separation system.

  1. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

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

  2. Characterization of boron carbide with an electron microprobe

    Science.gov (United States)

    Matteudi, G.; Ruste, J.

    1983-01-01

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

  3. Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Krivezhenko, Dina S., E-mail: dinylkaa@yandex.ru; Drobyaz, Ekaterina A., E-mail: ekaterina.drobyaz@yandex.ru; Bataev, Ivan A., E-mail: ivanbataev@ngs.ru; Chuchkova, Lyubov V., E-mail: twitty-kun@mail.ru [Novosibirsk State Technical University, Novosibirsk, 630073 (Russian Federation)

    2015-10-27

    An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to an enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.

  4. Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

    Science.gov (United States)

    Krivezhenko, Dina S.; Drobyaz, Ekaterina A.; Bataev, Ivan A.; Chuchkova, Lyubov V.

    2015-10-01

    An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to an enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.

  5. First gaseous boronization during pulsed discharge cleaning

    Science.gov (United States)

    Ko, J.; Den Hartog, D. J.; Goetz, J. A.; Weix, P. J.; Limbach, S. T.

    2013-01-01

    The first successful gaseous boronization during a pulsed discharge is reported. Sublimation of o-carborane (C2B10H12) combined with pulsed discharge plasmas with a repetition rate of 1 Hz is used to produce a hard boron-containing coating for reversed field pinch (RFP) plasmas in the Madison Symmetric Torus. X-ray photoelectron spectroscopy with Ar ion beam etching for silicon coupons installed at the plasma boundary shows about 60% boron concentration in the deposited layer. Both profilometer and scanning electron microscope analyses of the silicon coupons imply a strong toroidally non-uniform deposition depending on the location of the o-carborane injection. The layer thickness ranges from 50 to 300 nm. Ellipsometry calibrated with the profilometer results yields a refractive index of 2.2-2.3 for the films. The high refractive index implies that the coating is hard and has a well-ordered morphology. A reduction in wall recycling has consistently been observed after all boronization sessions. Comparison of the X-ray spectra in standard RFP plasmas before and after boronization indicates a slight decrease in the effective ionic charge.

  6. First gaseous boronization during pulsed discharge cleaning

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-15

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

  7. Axial residual stresses in boron fibers

    Science.gov (United States)

    Behrendt, D. R.

    1978-01-01

    A method of measuring axial residual stresses in boron fibers is presented. With this method, the axial residual stress distribution as a function of radius is determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diam fibers are similar, being compressive at the surface and changing monotonically to a region of tensile stress within the boron. At approximately 25% of the original radius, the stress reaches a maximum tensile stress of about 860 MN sq m and then decreases to a compressive stress near the tungsten boride core. Data are presented for 203-micron diam B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102-micron diam B/W and boron on carbon (B/C) show that the residual stresses are similar in the outer regions of the fibers, but that large differences near and in the core are observed. Fracture of boron fibers is discussed.

  8. Electromagnetic properties and microstructures of in situ MgB2 wires made from three types of boron powders

    Science.gov (United States)

    Kodama, Motomune; Kotaki, Hiroshi; Yamamoto, Hiroyuki; Iwane, Tomohiro; Tanaka, Kazuhide; Tanaka, Hideki; Okishiro, Kenji; Okamoto, Kazutaka; Nishijima, Gen; Matsumoto, Akiyoshi; Kumakura, Hiroaki; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Kishio, Kohji

    2016-10-01

    In powder-in-tube processed MgB2 wires, the choice of boron powder as a starting material crucially affects their performance. In this paper, we prepared in situ MgB2 wires from three types of boron powders in various heat-treatment conditions and investigated their electromagnetic properties and microstructures. Their critical current density, J c, varied over a wide range from sample to sample. The difference in J c is understood to be caused by the effect of changes in the electrical connectivity, K, and intrinsic residual resistivity, ρ 0. Here, K represents the effective cross-sectional area for current, and ρ 0 reflects the degree of the charge carrier scattering caused by lattice defects. It was found that the use of boron powder with a large specific surface area leads to a large degree of lattice defects in MgB2 grains and enhances ρ 0, resulting in improving J c. The boron powder produced by thermal decomposition of B2H6 has a large specific surface area. Hence, this boron powder is the most suitable as a starting material for MgB2. Meanwhile, dry pulverization of low-cost boron powder, which is largely produced by active-metal reduction of B2O3, is also effective to increase its specific surface area without introducing impurities, resulting in the enhancement of J c in the entire magnetic field region. This finding broadens the choice of boron powder and contributes to realizing superconducting applications with excellent balance between performance and cost.

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

    Directory of Open Access Journals (Sweden)

    N. F. Nevar

    2010-01-01

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

  10. Estudo da circulação hepatomesentérica pela angiografia por ressonância magnética com gadolínio: comparação entre doses simples e dupla no estudo de pacientes esquistossomóticos Gadolinium-enhanced magnetic resonance angiography for hepatomesenteric vascular evaluation: single and double doses comparison in schistosomiasis patients

    Directory of Open Access Journals (Sweden)

    Rogério Pedreschi Caldana

    2006-08-01

    Full Text Available OBJETIVO: Determinar a freqüência de visualização dos segmentos da circulação hepatomesentérica pela angiografia por ressonância magnética (angio-RM com contraste e comparar o valor do método, utilizando-se duas diferentes dosagens de gadolínio (doses simples e dupla. MATERIAIS E MÉTODOS: Estudo prospectivo de 36 pacientes esquistossomóticos submetidos a angio-RM. Os exames foram realizados em equipamento de RM de 1,5 T, usando-se bobina de corpo e bomba injetora para a administração endovenosa do contraste. Foram utilizadas, de maneira randomizada, dose dupla do contraste paramagnético (0,2 mmol/kg de Gd-DTPA em 21 pacientes e dose simples (0,1 mmol/kg em outros 15 pacientes. Os exames foram interpretados por dois observadores em consenso, que classificaram o grau de visualização de 25 segmentos vasculares estabelecidos para análise, sem conhecimento da dose de gadolínio utilizada. RESULTADOS: Os segmentos vasculares proximais e de maior calibre foram as estruturas com melhor grau de visualização na maioria da amostra em estudo. O tronco celíaco, a artéria hepática comum, a artéria esplênica, a croça e terço médio da artéria mesentérica superior, a veia porta, a veia esplênica e a veia mesentérica superior apresentaram grau 2 de visualização em mais de 70% da amostra. Quanto à comparação das diferentes dosagens, não houve diferença significante (p OBJECTIVE: To evaluate the visibility of hepatomesenteric vascular segments by 3D gadolinium-enhanced magnetic resonance (MR angiography and to compare the method effectiveness between two different gadolinium doses (single and double doses. MATERIALS AND METHODS: A prospective study was performed with 36 schistosomiasis patients who were submitted to 3D contrast-enhanced MR angiography. Scans were performed in a high-field equipment (1.5 T, with body coil and power injector for intravenous contrast administration. Contrast double doses (Gd-DTPA 0.2 mmol/kg and

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

    Science.gov (United States)

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

  12. Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron.

    Science.gov (United States)

    Horitsugi, Genki; Fujibuchi, Toshioh; Yamaguchi, Ichiro; Eto, Akihisa; Iwamoto, Yasuo; Hashimoto, Hiromi; Hamada, Seiki; Obara, Satoshi; Watanabe, Hiroshi; Hatazawa, Jun

    2012-07-01

    The cyclotron at our hospital has a self-shield of boron-containing water. The amount of induced radioactivity in the boron-containing water shield of a compact medical cyclotron has not yet been reported. In this study, we measured the photon and neutron dose rates outside the self-shield during cyclotron operation. We estimated the induced radioactivities of the boron-containing water used for the self-shield and then measured them. We estimated the activation of concrete outside the self-shield in the cyclotron laboratory. The thermal neutron flux during cyclotron operation was estimated to be 4.72 × 10(2) cm(-2) s(-1), and the activation of concrete in a cyclotron laboratory was about three orders of magnitude lower than the clearance level of RS-G-1.7 (IAEA). The activity concentration of the boron-containing water did not exceed the concentration limit for radioactive isotopes in drainage in Japan and the exemption level for Basic Safety Standards. Consequently, the boron-containing water is treatable as non-radioactive waste. Neutrons were effectively shielded by the self-shield during cyclotron operation.

  13. Radiation quality evaluation in heavy water field using tissue equivalent-proportional counter with wall containing boron

    Energy Technology Data Exchange (ETDEWEB)

    Onizuka, Y. [Kyushu Univ., Faculty of Medicine, Fukuoka (Japan); Endo, S.; Ishikawa, M. [Hiroshima Univ., Research Inst. for Radiation Biology and Medicine, Hiroshima (JP)] [and others

    2003-01-01

    A heavy water installation at the Kyoto University Reactor (KUR) is used for the boron neutron capture therapy. The contributions of boron neutron capture reaction to the dose are required for the evaluation of the boron neutron capture therapy in relation to the biological effectiveness. The radiation therapy fields are measured by a technique of micro-dosimetry. Three types of tissue equivalent-proportional counter are used for measurement of the radiation therapy fields; a LET counter with wall containing boron for thermal neutrons, a LET counter with wall containing no boron for epithermal neutrons, and a helical wire proportional counter with carbon wall for gamma rays. Irradiations of the counters are carried out in the neutron capture therapy fields with two modes, a thermal neutron mode and an epithermal neutron mode. An acrylic plate is used for human body phantom. Each energy spectrum in the counters is measured at depth 6.7 mm in the phantom by multi-channel analyzer. The energy spectra in three types of the counters show that most of neutron energy transfers to the effects of {sup 4}He(1.49 MeV) and {sup 7}Li(0.85 MeV) following to thermal neutron capture reactions of {sup 10}B in the wall. (M. Suetake)

  14. Enhancement of trace-element content of cabbages grown in urban areas

    Energy Technology Data Exchange (ETDEWEB)

    Purves, D.; MacKenzie, E.J.

    1970-01-01

    Significantly higher contents of boron, molybdenum and zinc were observed in cabbages in urban than in rural areas. The levels of extractable boron, copper, lead, nickel and zinc were markedly enhanced in the urban soils but there was no corresponding enhancement of the levels of copper, lead and nickel in the cabbages. 10 references, 2 tables.

  15. Oxygen radical functionalization of boron nitride nanosheets.

    Science.gov (United States)

    Sainsbury, Toby; Satti, Amro; May, Peter; Wang, Zhiming; McGovern, Ignatius; Gun'ko, Yurii K; Coleman, Jonathan

    2012-11-14

    The covalent chemical functionalization of exfoliated hexagonal boron-nitride nanosheets (BNNSs) is achieved by the solution-phase oxygen radical functionalization of boron atoms in the h-BN lattice. This involves a two-step procedure to initially covalently graft alkoxy groups to boron atoms and the subsequent hydrolytic defunctionalization of the groups to yield hydroxyl-functionalized BNNSs (OH-BNNSs). Characterization of the functionalized-BNNSs using HR-TEM, Raman, UV-vis, FTIR, NMR, and TGA was performed to investigate both the structure of the BNNSs and the covalent functionalization methodology. OH-BNNSs were used to prepare polymer nanocomposites and their mechanical properties analyzed. The influence of the functional groups grafted to the surface of the BNNSs is investigated by demonstrating the impact on mechanical properties of both noncovalent and covalent bonding at the interface between the nanofiller and polymer matrixes.

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

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

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

  17. Growth evaluation of spondias tuberosa rootsctocks in the substrate fertilization with nitrogen and boron.

    Directory of Open Access Journals (Sweden)

    Cleiton José de Oliveira

    2009-08-01

    Full Text Available The main goal of this works was evaluate the effect of nitrogen and boron doses, in the rootstocks ‘umbu’ (Spondias tuberosa Arruda Câmara. The experiment it was led at CCA/UFPB-Campus II, located in the Areia city, state of Paraiba in Brazil. The treatments were five levels of nitrogen (0 to 4,50 g dm-3 as ureia (45% N, and five boron doses (0 to 3,0 mg dm-3, as borax (11% B, applied in the subtract constituted by the mixture of 75% of soil and 25% of manure bovine, in the randomized blocks design, with four repetitions. The experimental unit was constituted of three recipient containing three seedlings. It was evaluated height and the diameter of the stem of the seedlings, besides the mass of the matter evaporates and the areas of the root system and aerial part. The increase of the levels of nitrogen resulted in smaller growth of the seedlings. The application of 3 mg dm-3 of the boron provided the largest growth of the aerial parts and root.Key-words: Spondias tuberosa, mixture, fertilization

  18. Ultrahard nanotwinned cubic boron nitride.

    Science.gov (United States)

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

    2013-01-17

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

  19. Boron nitride nanotubes for spintronics.

    Science.gov (United States)

    Dhungana, Kamal B; Pati, Ranjit

    2014-09-22

    With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics.

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

    Science.gov (United States)

    Hunt, Curtiss D

    2012-06-01

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

  1. Nuclear quadrupole resonance of boron in borate glasses

    Science.gov (United States)

    Gravina, Samuel J.; Bray, Phillip J.

    A continuous wave nuclear quadrupole resonance spectrometer that has a high sensitivity even at low frequencies has been built. Boron and aluminum NQR has been detected in the region 200 kHz to 1.4 MHz. For the first time, boron NQR has been detected in a glass. The NQR spectrum of pure B 20 3 glass is consistent with 85 ± 2% of the boron atoms belonging to boroxol rings. In sodium borate glasses, the number of borons in boroxol rings decreases with increasing sodium content, until when sodium oxide comprises 20 mol% of the glass less than 2% of the borons are in boroxol rings.

  2. Removal of boron from ceramic industry wastewater by adsorption-flocculation mechanism using palm oil mill boiler (POMB) bottom ash and polymer.

    Science.gov (United States)

    Chong, Mei Fong; Lee, Kah Peng; Chieng, Hui Jiun; Syazwani Binti Ramli, Ili Izyan

    2009-07-01

    Boron is extensively used in the ceramic industry for enhancing mechanical strength of the tiles. The discharge of boron containing wastewater to the environment causes severe pollution problems. Boron is also dangerous for human consumption and causes organisms' reproductive impediments if the safe intake level is exceeded. Current methods to remove boron include ion-exchange, membrane filtration, precipitation-coagulation, biological and chemical treatment. These methods are costly to remove boron from the wastewater and hence infeasible for industrial wastewater treatment. In the present research, adsorption-flocculation mechanism is proposed for boron removal from ceramic wastewater by using Palm Oil Mill Boiler (POMB) bottom ash and long chain polymer or flocculant. Ceramic wastewater is turbid and milky in color which contains 15 mg/L of boron and 2000 mg/L of suspended solids. The optimum operating conditions for boron adsorption on POMB bottom ash and flocculation using polymer were investigated in the present research. Adsorption isotherm of boron on bottom ash was also investigated to evaluate the adsorption capacity. Adsorption isotherm modeling was conducted based on Langmuir and Freundlich isotherms. The results show that coarse POMB bottom ash with particle size larger than 2 mm is a suitable adsorbent where boron is removed up to 80% under the optimum conditions (pH=8.0, dosage=40 g bottom ash/300 ml wastewater, residence time=1h). The results also show that KP 1200 B cationic polymer is effective in flocculating the suspended solids while AP 120 C anionic polymer is effective in flocculating the bottom ash. The combined cationic and anionic polymers are able to clarify the ceramic wastewater under the optimum conditions (dosage of KP 1200 B cationic polymer=100 mg/L, dosage of AP 120 C anionic polymer=50 mg/L, mixing speed=200 rpm). Under the optimum operating conditions, the boron and suspended solids concentration of the treated wastewater were

  3. Modeling of Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig

    Science.gov (United States)

    Gnoffo, Peter A.; Fay, Catharine C.

    2012-01-01

    Flow in a pressurized, vapor condensation (PVC) boron nitride nanotube (BNNT) production rig is modeled. A laser provides a thermal energy source to the tip of a boron ber bundle in a high pressure nitrogen chamber causing a plume of boron-rich gas to rise. The buoyancy driven flow is modeled as a mixture of thermally perfect gases (B, B2, N, N2, BN) in either thermochemical equilibrium or chemical nonequilibrium assuming steady-state melt and vaporization from a 1 mm radius spot at the axis of an axisymmetric chamber. The simulation is intended to define the macroscopic thermochemical environment from which boron-rich species, including nanotubes, condense out of the plume. Simulations indicate a high temperature environment (T > 4400K) for elevated pressures within 1 mm of the surface sufficient to dissociate molecular nitrogen and form BN at the base of the plume. Modifications to Program LAURA, a finite-volume based solver for hypersonic flows including coupled radiation and ablation, are described to enable this simulation. Simulations indicate that high pressure synthesis conditions enable formation of BN vapor in the plume that may serve to enhance formation of exceptionally long nanotubes in the PVC process.

  4. Characteristics of Boron Decorated TiO2 Nanoparticles for Dye-Sensitized Solar Cell Photoanode

    Directory of Open Access Journals (Sweden)

    Ching-Yuan Ho

    2015-01-01

    Full Text Available Different boron weight percents on mixed-phase (anatase and rutile TiO2 nanoparticles were synthesized to investigate structure morphology, defect states, luminescence properties, and energy conversion. The measured results indicate that boron doping of TiO2 both increases the crystallite size and rutile-phase percent in an anatase matrix. Decreasing the band gap by boron doping can extend the absorption to the visible region, while undoped TiO2 exhibits high UV absorption. Oxygen vacancy defects generated by boron ions reduce Ti+4 and affect electron transport in dye-sensitized solar cells. Excess electrons originating from the oxygen vacancies of doped TiO2 downward shift in the conduction band edge and prompt the transfer of photoelectrons from the conduction band of the rutile phase to the lower energy anatase trapping sites; they then separate charges to enhance the photocurrent and Jsc. Although the resistance of the electron recombination (Rk between doped TiO2 photoanode and the electrolyte for the doped TiO2 sample is lower, a longer electron lifetime (τ of 19.7 ms with a higher electron density (ns of 2.1 × 1018 cm−3 contributes to high solar conversion efficiency.

  5. Boron doping compensation of hydrogenated amorphous and polymorphous germanium thin films for infrared detection applications

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, M., E-mail: mmoreno@inaoep.mx [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Delgadillo, N. [Universidad Autónoma de Tlaxcala, Av. Universidad No. 1, Z. P. 90006 Tlaxcala (Mexico); Torres, A. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico); Ambrosio, R. [Technology and Engineering Institute, Ciudad Juarez University UACJ, Av. Del Charro 450N, Z. P. 32310 Chihuahua (Mexico); Rosales, P.; Kosarev, A.; Reyes-Betanzo, C.; Hidalga-Wade, J. de la; Zuniga, C.; Calleja, W. [National Institute of Astrophysics, Optics and Electronics, INAOE, P.O. Box 51 and 216, Puebla, Z. P. 72840 Puebla (Mexico)

    2013-12-02

    In this work we have studied boron doping of hydrogenated amorphous germanium a-Ge:H and polymorphous germanium (pm-Ge:H) in low regimes, in order to compensate the material from n-type (due to oxygen contamination that commonly occurs during plasma deposition) to intrinsic, and in this manner improve the properties that are important for infrared (IR) detection, as activation energy (E{sub a}) and temperature coefficient of resistance (TCR). Electrical, structural and optical characterization was performed on the films produced. Measurements of the temperature dependence of conductivity, room temperature conductivity (σ{sub RT}), E{sub a} and current–voltage characteristics under IR radiation were performed in the compensated a-Ge:H and pm-Ge:H films. Our results demonstrate that, effectively, the values of E{sub a}, TCR and IR detection are improved on the a-Ge:H/pm-Ge:H films, using boron doping in low regimes, which results of interest for infrared detectors. - Highlights: • We reported boron doping compensation of amorphous and polymorphous germanium. • The films were deposited by plasma enhanced chemical vapor deposition. • The aim is to use the films as thermo-sensing elements in un-cooled microbolometers. • Those films have advantages over boron doped a-Si:H used in commercial detectors.

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

    CERN Document Server

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

    2009-01-01

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

  7. Hollow boron nitride nanospheres as boron reservoir for prostate cancer treatment

    Science.gov (United States)

    Li, Xia; Wang, Xiupeng; Zhang, Jun; Hanagata, Nobutaka; Wang, Xuebin; Weng, Qunhong; Ito, Atsuo; Bando, Yoshio; Golberg, Dmitri

    2017-01-01

    High global incidence of prostate cancer has led to a focus on prevention and treatment strategies to reduce the impact of this disease in public health. Boron compounds are increasingly recognized as preventative and chemotherapeutic agents. However, systemic administration of soluble boron compounds is hampered by their short half-life and low effectiveness. Here we report on hollow boron nitride (BN) spheres with controlled crystallinity and boron release that decrease cell viability and increase prostate cancer cell apoptosis. In vivo experiments on subcutaneous tumour mouse models treated with BN spheres demonstrated significant suppression of tumour growth. An orthotopic tumour growth model was also utilized and further confirmed the in vivo anti-cancer efficacy of BN spheres. Moreover, the administration of hollow BN spheres with paclitaxel leads to synergetic effects in the suppression of tumour growth. The work demonstrates that hollow BN spheres may function as a new agent for prostate cancer treatment.

  8. MAGIC polymer gel for dosimetric verification in boron neutron capture therapy.

    Science.gov (United States)

    Uusi-Simola, Jouni; Heikkinen, Sami; Kotiluoto, Petri; Serén, Tom; Seppälä, Tiina; Auterinen, Iiro; Savolainen, Sauli

    2007-04-30

    Radiation sensitive polymer gels are among the most promising three-dimensional dose verification tools developed to date. Polymer gel dosimeter known by the acronym MAGIC has been tested for evaluation of its use in boron neutron capture (BNCT) dosimetry. We irradiated a large (diameter 10 cm, length 20 cm) cylindrical gel phantom in the epithermal neutron beam of the Finnish BNCT facility at the FiR 1 nuclear reactor. Neutron irradiation was simulated with a Monte Carlo radiation transport code MCNP. Gel samples from the same production batch were also irradiated with 6 MV photons from a medical linear accelerator to compare dose response in the two different types of beams. Irradiated gel phantoms were imaged using MRI to determine their relaxation rate R2 maps. The measured and normalized dose distribution in the epithermal neutron beam was compared to the dose distribution calculated by computer simulation. The results support the feasibility MAGIC gel in BNCT dosimetry.

  9. Effect of boron and zinc fertilization on white oats grown in soil with average content of these nutrients

    Directory of Open Access Journals (Sweden)

    Deise Dalazen Castagnara

    2012-07-01

    Full Text Available The objective of this study was to evaluate the effect of fertilization with zinc or boron on the growth and dry matter production, nutritional value and accumulation of nutrients in white oats. The study comprised two experiments conducted in glasshouses, the first consisting of the application of four doses of zinc (0, 0.2, 0.4 and 0.6 mg/dm³ in the form of zinc sulphate (20% Zn, and the second consisting of the application of four doses of boron (0, 0.2, 0.4 and 0.6 mg/dm³ in the form of Borax (11% B. The experimental design in each case was a randomized block design, with five replicates. Fertilization with zinc and boron increased the growth of white oats, but had no significant effect on the nutritional value of the forage. Higher levels of absorption and accumulation of nutrients in plant tissues were observed following the application of boron and zinc at rates of up to 0.60 mg/dm³ of soil.

  10. Relationship Between Soil Boron Adsorption Kinetics and Rape Plant Boron Response

    Institute of Scientific and Technical Information of China (English)

    ZHUDUANWEI; PIMEIMEI; 等

    1997-01-01

    The boron adsorption kinetic experiment in soil by means a flow displacement technique showed that the kinetic data could be described with some mathematic equations.The average values of the coorealtion coefficeint for zero-order,first-order,parabolic diffusion ,Elovich,power function and eponential equations were 0.957,0.982,0.981,0.984,0.981 and 0.902 ,respectively,The correlation between adsorbed boron or its other expression form and time were the highest for first-order ,parabloic diffusion Elovich,and pwer function equations,the second for the zeroorder equation,and the tlowest for the exponential equation.The parabloic diffusion equation fitted well the expermiental results,with the least standard error among the six kinetic equation,showing that the monvemetn of boron from soil solution to soil colloid surface may be controlled by boron diffusion speed.The boron content of rape seedling obtained from soil cultvation was correlated with the rate constants of the kinetic equations.The constants of first-order ,parabloic diffusion,and exponential equaitions were significanlty correlated with the boron content of the crop of NPK treatment at a 95% probaility level ,with correation coeffecients being 0.686,0.691 and 0.64 and 0.641,respectively.In the case of zero-order equation,it Was significant at 99% probability level(r=0.736),These results showed that the adsorption kinetic constants of soil boron were closely related with the rape plant response to boron.

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

    Science.gov (United States)

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

    2016-09-01

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

  12. A New Saccharides and Nnucleosides Sensor Based on Tetrathiafulvalene-anthracene Dyad with Two Boronic Acid Groups

    Directory of Open Access Journals (Sweden)

    Daoben Zhu

    2006-08-01

    Full Text Available A new saccharides sensor based on the TTF-anthracene dyad with two boronicacid (2 groups was designed and synthesized. This new saccharides sensor showsselectivity towards D-glucose while its analogue with one boronic acid group (1 wasreported to bind D-Fructose selectively. Moreover, reaction of compound 2 with uridineinduced even larger fluorescence enhancement under the same condition.

  13. Boron neutron capture therapy (BNCT) for glioblastoma multiforme using the epithermal neutron beam at the Brookhaven Medical Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Capala, J. [Brookhaven National Lab., Upton, NY (United States); Diaz, A.Z.; Chadha, M. [Univ. Hospital, State Univ. of New York, NY (United States)] [and others

    1997-12-31

    The abstract describes evaluation of boron neutron capture therapy (BNCT) for two groups of glioblastoma multiforme patients. From September 1994 to February 1996 15 patients have been treated. In September 1997 another 34 patients were examined. Authors determined a safe starting dose for BNCT using epithermal neutrons and BPA-F. They have also evaluated adverse effects of BNCT at this starting dose. Therapeutic effectiveness of this starting dose has been evaluated. No significant side effects from BPA-F infusion or BNCT treatment were observed in normal brains.

  14. Impact of implanted phosphorus on the diffusivity of boron and its applicability to silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schrof, Julian, E-mail: julian.schrof@ise.fraunhofer.de; Müller, Ralph; Benick, Jan; Hermle, Martin [Fraunhofer Institute for Solar Energy Systems (ISE), Heidenhofstrasse 2, D-79110 Freiburg (Germany); Reedy, Robert C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, Colorado 80401 (United States)

    2015-07-28

    Boron diffusivity reduction in extrinsically doped silicon was investigated in the context of a process combination consisting of BBr{sub 3} furnace diffusion and preceding Phosphorus ion implantation. The implantation of Phosphorus leads to a substantial blocking of Boron during the subsequent Boron diffusion. First, the influences of ion implantation induced point defects as well as the initial P doping on B diffusivity were studied independently. Here, it was found that not the defects created during ion implantation but the P doping itself results in the observed B diffusion retardation. The influence of the initial P concentration was investigated in more detail by varying the P implantation dose. A secondary ion mass spectrometry (SIMS) analysis of the BSG layer after the B diffusion revealed that the B diffusion retardation is not due to potential P content in the BSG layer but rather caused by the n-type doping of the crystalline silicon itself. Based on the observations the B diffusion retardation was classified into three groups: (i) no reduction of B diffusivity, (ii) reduced B diffusivity, and (iii) blocking of the B diffusion. The retardation of B diffusion can well be explained by the phosphorus doping level resulting in a Fermi level shift and pairing of B and P ions, both reducing the B diffusivity. Besides these main influences, there are probably additional transient phenomena responsible for the blocking of boron. Those might be an interstitial transport mechanism caused by P diffusion that reduces interstitial concentration at the surface or the silicon/BSG interface shift due to oxidation during the BBr{sub 3} diffusion process. Lifetime measurements revealed that the residual (non-blocked) B leads to an increased dark saturation current density in the P doped region. Nevertheless, electrical quality is on a high level and was further increased by reducing the B dose as well as by removing the first few nanometers of the silicon surface after

  15. Impact of implanted phosphorus on the diffusivity of boron and its applicability to silicon solar cells

    Science.gov (United States)

    Schrof, Julian; Müller, Ralph; Reedy, Robert C.; Benick, Jan; Hermle, Martin

    2015-07-01

    Boron diffusivity reduction in extrinsically doped silicon was investigated in the context of a process combination consisting of BBr3 furnace diffusion and preceding Phosphorus ion implantation. The implantation of Phosphorus leads to a substantial blocking of Boron during the subsequent Boron diffusion. First, the influences of ion implantation induced point defects as well as the initial P doping on B diffusivity were studied independently. Here, it was found that not the defects created during ion implantation but the P doping itself results in the observed B diffusion retardation. The influence of the initial P concentration was investigated in more detail by varying the P implantation dose. A secondary ion mass spectrometry (SIMS) analysis of the BSG layer after the B diffusion revealed that the B diffusion retardation is not due to potential P content in the BSG layer but rather caused by the n-type doping of the crystalline silicon itself. Based on the observations the B diffusion retardation was classified into three groups: (i) no reduction of B diffusivity, (ii) reduced B diffusivity, and (iii) blocking of the B diffusion. The retardation of B diffusion can well be explained by the phosphorus doping level resulting in a Fermi level shift and pairing of B and P ions, both reducing the B diffusivity. Besides these main influences, there are probably additional transient phenomena responsible for the blocking of boron. Those might be an interstitial transport mechanism caused by P diffusion that reduces interstitial concentration at the surface or the silicon/BSG interface shift due to oxidation during the BBr3 diffusion process. Lifetime measurements revealed that the residual (non-blocked) B leads to an increased dark saturation current density in the P doped region. Nevertheless, electrical quality is on a high level and was further increased by reducing the B dose as well as by removing the first few nanometers of the silicon surface after the BBr3

  16. Multi-dimensional boron transport modeling in subchannel approach: Part II. Validation of CTF boron tracking model and adding boron precipitation model

    Energy Technology Data Exchange (ETDEWEB)

    Ozdemir, Ozkan Emre, E-mail: ozdemir@psu.edu; Avramova, Maria N., E-mail: mna109@psu.edu

    2014-10-15

    Highlights: • Validation of implemented multi-dimensional subchannel boron transport model. • Extension of boron transport model to entrained droplets. • Implementation of boron precipitation model. • Testing of the boron precipitation model under transient condition. - Abstract: The risk of small-break loss of coolant accident (SB-LOCA) and other reactivity initiated transients caused by boron dilution in the light water reactors (LWRs), and the complications of tracking the soluble boron concentration experimentally inside the primary coolant have stimulated the interest in computational studies for accurate boron tracking simulations in nuclear reactors. In Part I of this study, the development and implementation of a multi-dimensional boron transport model with modified Godunov scheme based on a subchannel approach within the COBRA-TF (CTF) thermal-hydraulic code was presented. The modified Godunov scheme approach with a physical diffusion term was determined to provide the most accurate and precise solution. Current paper extends these conclusions and presents the model validation studies against experimental data from the Rossendorf coolant mixing model (ROCOM) test facility. In addition, the importance of the two-phase flow characteristics in modeling boron transient are emphasized, especially during long-term cooling period after the loss of coolant accident (LOCA) condition in pressurized water reactors (PWRs). The CTF capabilities of boron transport modeling are further improved based on the three-field representation of the two-phase flow utilized in the code. The boron transport within entrained droplets is modeled, and a model for predicting the boron precipitation under transient conditions is developed and tested. It is aimed to extend the applicability of CTF to reactor transient simulations, and particularly to a large-break loss of coolant accident (LB-LOCA) analysis.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

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

    Science.gov (United States)

    Rein, J E; Abernathey, R M

    1972-07-01

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

  19. Substitution reactions at boron atoms in metallacarboranes

    Energy Technology Data Exchange (ETDEWEB)

    Bregadze, Vladimir I; Timofeev, Sergei V; Sivaev, Igor B; Lobanova, Irina A [A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

    2004-05-31

    Data on substitution reactions at boron atoms in 10-12-vertex metallacarboranes, which are of fundamental and applied significance, are generalised. The possible mechanisms of substitution reactions and the influence of the metal fragment on substitution positions in the polyhedron are discussed.

  20. Catalytic Asymmetric Synthesis of Phosphine Boronates.

    Science.gov (United States)

    Hornillos, Valentín; Vila, Carlos; Otten, Edwin; Feringa, Ben L

    2015-06-26

    The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of α,β-unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good yields and high enantiomeric excess. The synthetic utility of the products is demonstrated through stereospecific transformations into multifunctional optically active compounds.

  1. NEW ADVANCES IN BORON SOIL CHEMISTRY

    Science.gov (United States)

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

  2. New insight into pecan boron nutrition

    Science.gov (United States)

    Alternate bearing by individual pecan [Carya illinoinensis (Wangenh.) K. Koch] trees is problematic for nut producers and processors. There are many unknowns regarding alternate bearing physiology, such as the relationship between boron and fruit set, nutmeat quality, and kernel maladies. Evidence...

  3. Trapping and Sympathetic Cooling of Boron Ions

    CERN Document Server

    Rugango, Rene; Shu, Gang; Brown, Kenneth R

    2016-01-01

    We demonstrate the trapping and sympathetic cooling of B$^{+}$ ions in a Coulomb crystal of laser-cooled Ca$^{+}$, We non-destructively confirm the presence of the both B$^+$ isotopes by resonant excitation of the secular motion. The B$^{+}$ ions are loaded by ablation of boron and the secular excitation spectrum also reveals features consistent with ions of the form B$_{n}^{+}$.

  4. Compaction of amorphous iron–boron powder

    DEFF Research Database (Denmark)

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

    1993-01-01

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

  5. NEW ADVANCES IN BORON SOIL CHEMISTRY - Paper

    Science.gov (United States)

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

  6. Boron carbide morphology changing under purification

    Science.gov (United States)

    Rahmatullin, I. A.; Sivkov, A. A.

    2015-10-01

    Boron carbide synthesized by using coaxial magnetoplasma accelerator with graphite electrodes was purified by two different ways. XRD-investigations showed content changing and respectively powder purification. Moreover TEM-investigations demonstrated morphology changing of product under purification that was discussed in the work.

  7. Pechmann Reaction Promoted by Boron Trifluoride Dihydrate

    Directory of Open Access Journals (Sweden)

    J. Mezger

    2005-08-01

    Full Text Available The Pechmann reaction of substituted phenols 1a-e with methyl acetoacetate (2 can be activated by boron trifluoride dihydrate (3 to give the corresponding 4-methyl- coumarin derivatives 4a-e in excellent yield (98-99 %.

  8. Investigating the Boron Requirement of Plants.

    Science.gov (United States)

    Bohnsack, Charles W.

    1991-01-01

    This article describes a simple and rapid method for using summer squash to investigate born deficiency in plants. Author asserts that students are likely to feel challenged by laboratory exercises and projects that focus on the role boron plays in plant growth because it is an unresolved problem in biology. (PR)

  9. Powdered Hexagonal Boron Nitride Reducing Nanoscale Wear

    Science.gov (United States)

    Chkhartishvili, L.; Matcharashvili, T.; Esiava, R.; Tsagareishvili, O.; Gabunia, D.; Margiev, B.; Gachechiladze, A.

    2013-05-01

    A morphology model is suggested for nano-powdered hexagonal boron nitride that can serve as an effective solid additive to liquid lubricants. It allows to estimate the specific surface, that is a hard-to-measure parameter, based on average size of powder particles. The model can be used also to control nanoscale wear processes.

  10. Molecular Medicine: Synthesis and In Vivo Detection of Agents for use in Boron Neutron Capture Therapy. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kabalka, G. W.

    2005-06-28

    The primary objective of the project was the development of in vivo methods for the detection and evaluation of tumors in humans. The project was focused on utilizing positron emission tomography (PET) to monitor the distribution and pharamacokinetics of a current boron neutron capture therapy (BNCT) agent, p-boronophenylalanine (BPA) by labeling it with a fluorine-18, a positron emitting isotope. The PET data was then used to develop enhanced treatment planning protocols. The study also involved the synthesis of new tumor selective BNCTagents that could be labeled with radioactive nuclides for the in vivo detection of boron.

  11. BCM6: New Generation of Boron Meter

    Energy Technology Data Exchange (ETDEWEB)

    Pirat, P. [Rolls-Royce Civil Nuclear SAS (France)

    2010-07-01

    Full text of publication follows: Rolls-Royce has developed a new generation of boron meter, based on more than 30 years of experience. The Rolls-Royce BCM6 boron meter provides Nuclear Power Plant (NPP) operators with the boron concentration of the primary circuit. The meter provides continuous and safe measurements with no manual sampling and no human contact. In this paper, technical features, advantages and customer benefits of the use of the new generation of Rolls-Royce BCM6 boron meter will be detailed. Values and associated alarms are provides over different media: 4-20 mA outputs, relays, displays in the main control room and in the chemical lab, and digital links. A special alarm avoids unexpected homogeneous dilution of the primary circuit, which is a critical operational parameter. The Rolls-Royce BCM6 boron meter is fully configurable over a set of parameters allowing adaptation to customer needs. It has a differential capability, thus eliminating neutronic noise and keeping measurements accurate, even in the case of fuel clad rupture. Measurements are accurate, reliable, and have a quick response time. Equipment meets state-of-the-art qualification requests. Designed in 2008, the BCM6 boron meter is the newest equipment of Rolls-Royce boron meters product line. It has been chosen to equip the French EPR NPP and complies with the state-of-the-art of the technology. Rolls-Royce has more than 30 years of experience in Instrumentation and Controls with more than 75 NPP units operating worldwide. All of this experience return has been put in this new generation of equipment to provide the customer with the best operation. About Rolls-Royce Rolls-Royce is a global business providing integrated power systems for use on land, at sea and in the air. The Group has a balanced business portfolio with leading market positions. Rolls-Royce has a broad range of civil nuclear expertise, including work related to licensing and safety reviews, engineering design

  12. The effect of grain boundary segregation of boron in cast alloy 718 on HAZ microfissuring -- a SIMS analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, X.; Chaturvedi, M.C. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Mechanical and Industrial Engineering; Richards, N.L. [Bristol Aerospace Ltd., Winnipeg, Manitoba (Canada); Jackman, J. [CANMET, Ottawa, Ontario (Canada)

    1997-08-01

    Secondary ion mass spectroscopy (SIMS) has been used to examine grain boundary segregation in cast alloy 718. The relationship between the boron segregation and the microfissuring tendency in heat affected zones (HAZ) around electron beam welds is discussed in this study. It is concluded that two types of segregation, namely equilibrium and non-equilibrium segregation, occurred during the homogenization heat treatment of the base material. Water quenching after the homogenization treatment inhibited non-equilibrium segregation of boron and other trace elements owing to insufficient time for diffusion of solute-vacancy complexes to occur. Intermediate cooling rates such as air cooling enhanced both non-equilibrium and equilibrium segregation, since equilibrium segregation occurred during holding at the heat treatment temperature. The value of net segregation produced by a combination of equilibrium segregation and non-equilibrium segregation varied with temperature in a U-shape. The nature of the grain boundary in the cast alloy was examined by using an electron backscattered diffraction (EBSD) technique and it was found that 93% of the grain boundaries were of the random type ({Sigma} > 49). The weldability of this alloy was found to be closely related to the grain boundary segregation of boron, i.e., the variation of HAZ total crack length (TCL) with pre-welding heat treatment temperatures has a trend similar to that of boron segregation with temperature after air cooling. Mechanisms for the effect of boron on HAZ microfissuring have been proposed.

  13. Separation and analysis of cis-diol-containing compounds by boronate affinity-assisted micellar electrokinetic chromatography.

    Science.gov (United States)

    Wang, Heye; Lü, Chenchen; Li, Hengye; Chen, Yang; Zhou, Min; Ouyang, Jian; Liu, Zhen

    2013-10-01

    Cis-diol-containing compounds (CDCCs) are usually highly hydrophilic compounds and are therefore difficult to separate by conventional reversed-phase-based micellar electrokinetic chromatography (MEKC) due to poor selectivity. Here, we report a new method, called boronate affinity-assisted micellar electrokinetic chromatography (BAA-MEKC), to solve this issue. A boronic acid with a hydrophobic alkyl chain was added to the background electrolyte, which acted as a modifier to adjust the selectivity. CDCCs can covalently react with the boronic acid to form negatively charged surfactant-like complexes, which can partition into micelles formed with a cationic surfactant. Thus, CDCCs can be separated according to the differential partition constants of their boronic acid complexes between the micellar phase and the surrounding aqueous phase. To verify this method, eight nucleosides were employed as the test compounds and their separation confirmed that the combination of boronate affinity interaction with MEKC can effectively enhance the separation of CDCCs. The effects of experimental conditions on the separation were investigated. Finally, the BAA-MEKC method was applied to the separation and analysis of nucleosides extracted from human urine. BAA-MEKC exhibited better selectivity and improved separation as compared with conventional MEKC and CZE. Successful quantitative analysis of urinary nucleosides by BAA-MEKC was demonstrated.

  14. Deposition of boron doped DLC films on TiNb and characterization of their mechanical properties and blood compatibility

    Science.gov (United States)

    Liza, Shahira; Hieda, Junko; Akasaka, Hiroki; Ohtake, Naoto; Tsutsumi, Yusuke; Nagai, Akiko; Hanawa, Takao

    2017-01-01

    Abstract Diamond-like carbon (DLC) material is used in blood contacting devices as the surface coating material because of the antithrombogenicity behavior which helps to inhibit platelet adhesion and activation. In this study, DLC films were doped with boron during pulsed plasma chemical vapor deposition (CVD) to improve the blood compatibility. The ratio of boron to carbon (B/C) was varied from 0 to 0.4 in the film by adjusting the flow rate of trimethylboron and acetylene. Tribological tests indicated that boron doping with a low B/C ratio of 0.03 is beneficial for reducing friction (μ = 0.1), lowering hardness and slightly increasing wear rate compared to undoped DLC films. The B/C ratio in the film of 0.03 and 0.4 exhibited highly hydrophilic surface owing to their high wettability and high surface energy. An in vitro platelet adhesion experiment was conducted to compare the blood compatibility of TiNb substrates before and after coating with undoped and boron doped DLC. Films with highly hydrophilic surface enhanced the blood compatibility of TiNb, and the best results were obtained for DLC with the B/C ratio of 0.03. Boron doped DLC films are promising surface coatings for blood contacting devices. PMID:28179961

  15. 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.

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

    KAUST Repository

    Valladares Linares, Rodrigo

    2014-07-17

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

  17. Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model.

    Science.gov (United States)

    Heber, Elisa M; Hawthorne, M Frederick; Kueffer, Peter J; Garabalino, Marcela A; Thorp, Silvia I; Pozzi, Emiliano C C; Monti Hughes, Andrea; Maitz, Charles A; Jalisatgi, Satish S; Nigg, David W; Curotto, Paula; Trivillin, Verónica A; Schwint, Amanda E

    2014-11-11

    The application of boron neutron capture therapy (BNCT) mediated by liposomes containing (10)B-enriched polyhedral borane and carborane derivatives for the treatment of head and neck cancer in the hamster cheek pouch oral cancer model is presented. These liposomes are composed of an equimolar ratio of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] (MAC) in the bilayer membrane while encapsulating the hydrophilic species Na3[ae-B20H17NH3] (TAC) in the aqueous core. Unilamellar liposomes with a mean diameter of 83 nm were administered i.v. in hamsters. After 48 h, the boron concentration in tumors was 67 ± 16 ppm whereas the precancerous tissue contained 11 ± 6 ppm, and the tumor/normal pouch tissue boron concentration ratio was 10:1. Neutron irradiation giving a 5-Gy dose to precancerous tissue (corresponding to 21 Gy in tumor) resulted in an overall tumor response (OR) of 70% after a 4-wk posttreatment period. In contrast, the beam-only protocol gave an OR rate of only 28%. Once-repeated BNCT treatment with readministration of liposomes at an interval of 4, 6, or 8 wk resulted in OR rates of 70-88%, of which the complete response ranged from 37% to 52%. Because of the good therapeutic outcome, it was possible to extend the follow-up of BNCT treatment groups to 16 wk after the first treatment. No radiotoxicity to normal tissue was observed. A salient advantage of these liposomes was that only mild mucositis was observed in dose-limiting precancerous tissue with a sustained tumor response of 70-88%.

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

    Science.gov (United States)

    Chu, T. L.

    1975-01-01

    The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk crystals of boron arsenide were prepared by the chemical