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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Xiaopeng; Jin, Hua; Ding, Zhanhui

2011-05-15

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

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

PubMed

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.

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

PubMed Central

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

2016-01-01

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 (10B) treatment. Interestingly, a rapid efflux of 10B from the roots of the transgenic plants was observed within 1 h of 10B 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. PMID:26902738

Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics

NASA Astrophysics Data System (ADS)

Ektarawong, A.; Simak, S. I.; Hultman, L.; Birch, J.; Tasnádi, F.; Wang, F.; Alling, B.

2016-04-01

The elastic properties of alloys between boron suboxide (B6O) and boron carbide (B13C2), denoted by (B6O)1-x(B13C2)x, as well as boron carbide with variable carbon content, ranging from B13C2 to B4C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B6O)1-x(B13C2)x is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic properties calculations demonstrate that configurational disorder in B13C2, where a part of the C atoms in the CBC chains substitute for B atoms in the B12 icosahedra, drastically increase the Young's and shear modulus, as compared to an atomically ordered state, B12(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B4C to B13C2. The elastic moduli of the (B6O)1-x(B13C2)x system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B6O)1-x(B13C2)x. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B6O-rich as well as ordered or disordered B13C2-rich domains in the material prepared through equilibrium routes is predicted.

OsNIP3;1, a rice boric acid channel, regulates boron distribution and is essential for growth under boron-deficient conditions.

PubMed

Hanaoka, Hideki; Uraguchi, Shimpei; Takano, Junpei; Tanaka, Mayuki; Fujiwara, Toru

2014-06-01

Boron is an essential micronutrient for higher plants. Boron deficiency is an important agricultural issue because it results in loss of yield quality and/or quantity in cereals and other crops. To understand boron transport mechanisms in cereals, we characterized OsNIP3;1, a member of the major intrinsic protein family in rice (Oryza sativa L.), because OsNIP3;1 is the most similar rice gene to the Arabidopsis thaliana boric acid channel genes AtNIP5;1 and AtNIP6;1. Yeast cells expressing OsNIP3;1 imported more boric acid than control cells. GFP-tagged OsNIP3;1 expressed in tobacco BY2 cells was localized to the plasma membrane. The accumulation of OsNIP3;1 transcript increased fivefold in roots within 6 h of the onset of boron starvation, but not in shoots. Promoter-GUS analysis suggested that OsNIP3;1 is expressed mainly in exodermal cells and steles in roots, as well as in cells around the vascular bundles in leaf sheaths and pericycle cells around the xylem in leaf blades. The growth of OsNIP3;1 RNAi plants was impaired under boron limitation. These results indicate that OsNIP3;1 functions as a boric acid channel, and is required for acclimation to boron limitation. Boron distribution among shoot tissues was altered in OsNIP3;1 knockdown plants, especially under boron-deficient conditions. This result demonstrates that OsNIP3;1 regulates boron distribution among shoot tissues, and that the correct boron distribution is crucial for plant growth. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohammadi, V., E-mail: V.Mohammadi@tudelft.nl; Nihtianov, S.

The lateral gas phase diffusion length of boron atoms, L{sub B}, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B{sub 2}H{sub 6}) is reported. The value of L{sub B} is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A L{sub B} = 2.2 mm was determined for boron deposition at 700 °C, while a L{sub B}more » of less than 1 mm was observed at temperatures lower than 500 °C.« less

Low Temperature Processing of Boron Carbide Cement Composite for Tough, Wear Resistant Structures

DTIC Science & Technology

1997-12-15

TITLE AND SUBTITLE Low Temperature Processing of Boron Carbide Cement Composite for Tough, Wear Resistant Structures 6. AUTHOR(S) Kristen J. Law...project has developed a low temperature polymer ceramic composite consisting of boron carbide layers bonded by cement, laminated with polymer...composite have been shown to compare favorably to those of partially sintered boron carbide. Applications for this material have been identified in

Selective boron delivery to murine tumors by lipophilic species incorporated in the membranes of unilamellar liposomes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feakes, D.A.; Shelly, K.; Hawthorne, M.F.

1995-02-28

The nido-carborane species K[nido-7-CH{sub 3}(CH{sub 2}){sub 15}-7,8-C{sub 2}B{sub 9}H{sub 11}] has been synthesized for use as an addend for the bilayer membrane of liposomes. Small unilamellar vesicles, composed of distearoylphosphatidylcholine/cholesterol, 1:1, and incorporating K[nido-7-CH{sub 3}(CH{sub 2}){sub 15}-7,8-C{sub 2}B{sub 9}H{sub 11}] in the bilayer, have been investigated in vivo. The time-course biodistribution of boron delivered by these liposomes was determined by inductively coupled plasma-atomic emission spectroscopy analyses after the injection of liposomal suspensions in BALB/c mice bearing EMT6 mammary adenocarcinomas. At the low injected doses normally used ({approx}5-10 mg of boron per kg of body weight), peak tumor boron concentrations ofmore » {approx}35 {mu}g of boron per g of tissue and tumor/blood boron ratios of {approx}8 were achieved. These values are sufficiently high for the successful application of boron neutron capture therapy. The bilayer-embedded boron compound may provide the sole boron source or, alternatively, a concentrated aqueous solution of a hydrophilic boron compound may also be encapsulated within the liposomes to provide a dose enhancement. Thus, the incorporation of both K[nido-7-CH{sub 3}(CH{sub 2}){sub 15}-7,8-C{sub 2}B{sub 9}H{sub 11}] and the hydrophilic species, Na{sub 3}[1-(2{prime}-B{sub 10}H{sub 9})-2-NH{sub 3}B{sub 10}H{sub 8}], within the same liposomes demonstrated significantly enhanced biodistribution characteristics, exemplified by maximum tumor boron concentrations of {approx} 50 {mu}g of boron per g of tissue and tumor/blood boron ratios of {approx} 6. 18 refs., 1 fig.« less

Assessment of Boron Steels for Army Use

DTIC Science & Technology

1978-11-01

I IA-79-0120 5 ys-g Aofc34V5 TECHNICAL LIBRARY AD ASSESSMENT OF BORON STEELS FOR ARMVlysr 3 ,% gL&tm tew^ / „»-^~ « "’"s4...ej ASSESSMENT OF BORON STEELS FOR ARMY USE 5. TYPE OF REPORT & PERIOD COVERED Final Report 6 PERFORMING ORG. REPORT NUMBER 7...reverse side 11 necessery rmd identify by block number) Boron steels Alloy conservation Alloy substitution Materials shortages 20. ABSTRACT

Exposure assessment of boron in Bandırma boric acid production plant.

PubMed

Duydu, Yalçin; Başaran, Nurşen; Bolt, Hermann M

2012-06-01

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 of 17.5mg B/kg-bw/day (corresponds to ∼2020 ng boron/g blood) has been identified for the (male) reproductive effects of boron in a multigenerational study of rats, and a NOAEL for the developmental effects in rats was identified at 9.6 mg B/kg-bw/day (corresponds to 1270 ng boron/g blood). These values are being taken as the basis of current EU safety assessments. The present study was conducted to assess the boron exposure under extreme exposure conditions in a boric acid production plant located in Bandırma, Turkey. The mean blood boron concentrations of low and high exposure groups were 72.94 ± 15.43 (48.46-99.91) and 223.89 ± 60.49 (152.82-454.02)ng/g respectively. The mean blood boron concentration of the high exposure group is still ≈ 6 times lower than the highest no effect level of boron in blood with regard to the developmental effects in rats and ≈ 9 times lower than the highest no effect level of boron in blood with regard to the reprotoxic effects in male rats. In this context, boric acid and sodium borates should not be considered as toxic to reproduction for humans in daily life. Copyright © 2012 Elsevier GmbH. All rights reserved.

Structural and electrical properties of trimethylboron-doped silicon nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lew, K.-K.; Pan Ling; Bogart, Timothy E.

2004-10-11

Trimethylboron (TMB) was investigated as a p-type dopant source for the vapor-liquid-solid growth of boron-doped silicon nanowires (SiNWs). The boron concentration in the nanowires was measured using secondary ion mass spectrometry and results were compared for boron-doping using TMB and diborane (B{sub 2}H{sub 6}) sources. Boron concentrations ranging from 1x10{sup 18} to 4x10{sup 19} cm{sup -3} were obtained by varying the inlet dopant/SiH{sub 4} gas ratio. TEM characterization revealed that the B{sub 2}H{sub 6}-doped SiNWs consisted of a crystalline core with a thick amorphous Si coating, while the TMB-doped SiNWs were predominantly single crystal even at high boron concentrations. Themore » difference in structural properties was attributed to the higher thermal stability and reduced reactivity of TMB compared to B{sub 2}H{sub 6}. Four-point resistivity and gate-dependent conductance measurements were used to confirm p-type conductivity in the TMB-doped nanowires and to investigate the effect of dopant concentration on nanowire resistivity.« less

Removal of boron (B) from waste liquors.

PubMed

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

2006-01-01

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

CHEMICAL METHODS FOR THE DETERMINATION OF BORON IN REACTOR MATERIALS. PART I. ION-EXCHANGE SEPARATION OF BORON FROM COKES, PITCHES AND GRAPHITES AND ITS COLORIMETRIC DETERMINATION BY THE CURCUMIN-TRI-CHLORACETIC ACID METHOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, H.B.; Desai, S.R.; Nadkarni, M.N.

1961-01-01

A procedure has been standardized for the determination of boron in cokes, pitches, and graphites. The method consists of fixing the boron present in the sample as calcium borate, ion-exchange separation of boric acid from the associated cations, and the colorimetric determination of boron using the curcumin-trichloracetic acid method. Sulfur which is usually present in pitches and cokes is expected to be oxidized to sulfate during the fixation of boron and hence its effect on the colorimetry has been studied. Application of the procedure to the determination of 0.50 and 1.00 microgram amounts of boron, has given coefficients of variationmore » of l0.0 and 6.7% respectively. (auth)« less

Effect of Hypoeutectic Boron Additions on the Grain Size and Mechanical Properties of Ti-6Al-4V Manufactured with Powder Bed Electron Beam Additive Manufacturing

NASA Astrophysics Data System (ADS)

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; Wojcieszynski, Andrzej; Dehoff, Ryan; Nandwana, Peeyush; Horn, Timothy

2017-03-01

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricated Ti-6Al-4V + B indicate that the addition of 0.25-1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.

Evaluation of Ground-Water and Boron Sources by Use of Boron Stable-Isotope Ratios, Tritium, and Selected Water-Chemistry Constituents near Beverly Shores, Northwestern Indiana, 2004

USGS Publications Warehouse

Buszka, Paul M.; Fitzpatrick, John A.; Watson, Lee R.; Kay, Robert T.

2007-01-01

Concentrations of boron greater than the U.S. Environmental Protection Agency (USEPA) 900 ?g/L removal action level (RAL) standard were detected in water sampled by the USEPA in 2004 from three domestic wells near Beverly Shores, Indiana. The RAL regulates only human-affected concentrations of a constituent. A lack of well logs and screened depth information precluded identification of whether water from sampled wells, and their boron sources, were from human-affected or natural sources in the surficial aquifer, or associated with a previously defined natural, confined aquifer source of boron from the subtill or basal sand aquifers. A geochemically-based classification of the source of boron in ground water could potentially determine the similarity of boron to known sources or mixtures between known sources, or classify whether the relative age of the ground water predated the potential sources of contamination. The U.S. Geological Survey (USGS), in cooperation with the USEPA, investigated the use of a geochemical method that applied boron stable isotopes, and concentrations of boron, tritium, and other constituents to distinguish between natural and human-affected sources of boron in ground water and thereby determine if the RAL was applicable to the situation. Boron stable-isotope ratios and concentrations of boron in 17 ground-water samples and tritium concentrations in 9 ground-water samples collected in 2004 were used to identify geochemical differences between potential sources of boron in ground water near Beverly Shores, Indiana. Boron and d11B analyses for this investigation were made on unacidified samples to assure consistency of the result with unacidified analyses of d11B values from other investigations. Potential sources of boron included surficial-aquifer water affected by coal-combustion products (CCP) or domestic-wastewater, upward discharge of ground water from confined aquifers, and unaffected water from the surficial aquifer that was distant from human-affected boron sources. Boron concentrations in potential ground-water sources of boron were largest (15,700 to 24,400 ?g/L) in samples of CCP-affected surficial aquifer water from four wells at a CCP landfill and smallest (27 to 63 ?g/L) in three wells in the surficial aquifer that were distant from human-affected boron sources. Boron concentrations in water from the basal sand aquifer ranged from 656 ?g/L to 1,800 ?g/L. Boron concentrations in water from three domestic-wastewater-affected surficial aquifer wells ranged from 84 to 387 ?g/L. Among the representative ground-water samples, boron concentrations from all four samples of CCP-affected surficial aquifer water and four of five samples of water from the basal sand aquifer had concentrations greater than the RAL. A comparison of boron concentrations in acid-preserved and unacidified samples indicated that boron concentrations reported for this investigation may be from about 11 to 16 percent less than would be reported in a standard analysis of an acidified sample. The stable isotope boron-11 was most enriched in comparison to boron-10 in ground water from a confined aquifer, the basal sand aquifer (d11B, 24.6 to 34.0 per mil, five samples); it was most depleted in CCP-affected water from the surficial aquifer (d11B, 0.1 to 6.6 per mil, four samples). Domestic-wastewater-affected water from the surficial aquifer (d11B, 8.7 to 11.7 per mil, four samples) was enriched in boron-11, in comparison to individual samples of a borax detergent additive and a detergent with perborate bleach; it was intermediate in composition between basal sand aquifer water and CCP-affected water from the surficial aquifer. The similarity between a ground-water sample from the surficial aquifer and a hypothetical mixture of unaffected surficial aquifer and basal sand aquifer waters indicates the potential for long-term upward discharge of ground water into the surficial aquifer from one or more confined aquifers. Est

The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters

DTIC Science & Technology

2016-01-04

AFRL-AFOSR-VA-TR-2016-0075 The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters KIT BOWEN JOHNS HOPKINS UNIV BALTIMORE MD...Hydride and Boron Aluminum Hydride Clusters 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0324 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) KIT...of both Aluminum Hydride Cluster Anions and Boron Aluminum Hydride Cluster Anions with Oxygen: Anionic Products The anionic products of reactions

Effect of Boron on Thymic Cytokine Expression, Hormone Secretion, Antioxidant Functions, Cell Proliferation, and Apoptosis Potential via the Extracellular Signal-Regulated Kinases 1 and 2 Signaling Pathway.

PubMed

Jin, Erhui; Ren, Man; Liu, Wenwen; Liang, Shuang; Hu, Qianqian; Gu, Youfang; Li, Shenghe

2017-12-27

Boron is an essential trace element in animals. Appropriate boron supplementation can promote thymus development; however, a high dose of boron can lead to adverse effects and cause toxicity. The influencing mechanism of boron on the animal body remains unclear. In this study, we examined the effect of boron on cytokine expression, thymosin and thymopoietin secretion, antioxidant function, cell proliferation and apoptosis, and extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway in the thymus of rats. We found that supplementation with 10 and 20 mg/L boron to the drinking water significantly elevated levels of interleukin 2 (IL-2), interferon γ (IFN-γ), interleukin 4 (IL-4), and thymosin α1 in the thymus of rats (p < 0.05), increased the number of positive proliferating cell nuclear antigen (PCNA + ) cells and concentrations of glutathione peroxidase (GSH-Px) and phosphorylated extracellular signal-regulated kinase (p-ERK) (p < 0.05), and promoted mRNA expression of PCNA and ERK1/2 in thymocytes (p < 0.05). However, the number of caspase-3 + cells and the expression level of caspase-3 mRNA were reduced (p < 0.05). Supplementation with 40, 80, and 160 mg/L boron had no apparent effect on many of the above indicators. In contrast, supplementation with 480 and 640 mg/L boron had the opposite effect on the above indicators in rats and elevated levels of pro-inflammatory cytokines, such as interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor α (TNF-α) (p < 0.05). Our study showed that supplementation of various doses of boron to the drinking water had a U-shaped dose-effect relationship with thymic cytokine expression, hormone secretion, antioxidant function, cell proliferation, and apoptosis. Specifically, supplementation with 10 and 20 mg/L boron promoted thymocyte proliferation and enhanced thymic functions. However, supplementation with 480 and 640 mg/L boron inhibited thymic functions and increased the number of apoptotic thymocytes, suggesting that the effects of boron on thymic functions may be caused via the ERK1/2 signaling pathway.

Boron deprivation alters rat behaviour and brain mineral composition differently when fish oil instead of safflower oil is the diet fat source.

PubMed

Nielsen, Forrest H; Penland, James G

2006-01-01

To determine whether boron deprivation affects rat behaviour and whether behavioural responses to boron deprivation are modified by differing amounts of dietary long-chain omega-3 fatty acids. Female rats were fed diets containing 0.1 mg (9 micromol)/kg boron in a factorial arrangement with dietary variables of supplemental boron at 0 and 3mg (278 micromol)/kg and fat sources of 75 g/kg safflower oil or 65 g/kg fish (menhaden) oil plus 10 g/kg linoleic acid. After 6 weeks, six females per treatment were bred. Dams and pups continued on their respective diets through gestation, lactation and after weaning. Between ages 6 and 20 weeks, behavioural tests were performed on 13-15 male offspring from three dams in each dietary treatment. The rats were euthanized at age 21 weeks for the collection of tissues and blood. At ages 6 and 19 weeks, auditory startle was evaluated with an acoustic startle system and avoidance behaviour was evaluated by using an elevated plus maze. At ages 7 and 20 weeks, spontaneous behaviour activity was evaluated with a photobeam activity system. A brightness discrimination test was performed on the rats between age 15 and 16 weeks. Brain mineral composition was determined by coupled argon plasma atomic emission spectroscopy. Plasma total glutathione was determined by HPLC and total cholesterol and 8-iso-prostaglandin F2alpha (8-iso-PGF2alpha) were determined by using commercially available kits. Boron-deficient rats were less active than boron-adequate rats when fed safflower oil based on reduced number, distance and time of horizontal movements, front entries, margin distance and vertical breaks and jumps in the spontaneous activity evaluation. Feeding fish oil instead of safflower oil attenuated the activity response to boron deprivation. In the plus maze evaluation, the behavioural reactivity of the boron-deficient rats fed fish oil was noticeably different than the other three treatments. They made more entries into both open and closed arms and the center area and thus visited more locations. The boron-deficient rats fed fish oil also exhibited the lowest copper and zinc and highest boron concentrations in brain and the highest plasma glutathione concentration. Both boron deprivation and safflower oil increased plasma 8-iso-PGF2alpha. Both dietary boron and long-chain omega-3 fatty acids influence rat behaviour and brain composition and the influence of one these bioactive substances can be altered by changing the intake of the other. Brain mineral and plasma cholesterol, glutathione and 8-iso-PGF2alpha findings suggest that rat behaviour is affected by an interaction between boron and fish oil because both affect oxidative metabolism and act the cellular membrane level.

Study of the boron levels in serum after implantation of different ratios nano-hexagonal boron nitride-hydroxy apatite in rat femurs.

PubMed

Atila, Alptug; Halici, Zekai; Cadirci, Elif; Karakus, Emre; Palabiyik, Saziye Sezin; Ay, Nuran; Bakan, Feray; Yilmaz, Sahin

2016-01-01

Boron and its derivatives are effective in bone recovery and osteointegration. However, increasing the boron levels in body liquids may cause toxicity. The aim of our study is to investigate serum boron levels using ICP-MS after implantation of different ratios of nano-hBN-HA composites in rat femurs. All rats were (n=126) divided into five experimental groups (n=24) and one healthy group (6 rats); healthy (Group1), femoral defect + %100 HA (Group2), femoral defect + %2.5 hBN + %97.5 HA (Group3), femoral defect + %5 hBN + %95 HA (Group4), femoral defect + %10 hBN + %90 HA (Group5), femoral defect + %100 hBN (Group6). The femoral defect was created in the distal femur (3mm drill-bit). Each implant group was divided into four different groups (n=24) also 6 rats sacrificed for each groups in one week intervals during four weeks. In our results; at 1, 2, 3, and 4 weeks after implantation near bone tissue, serum levels of boron were evaluated using ICP-MS. We demonstrated that neither short-term nor long-term implantation of hBN-HA composite resulted in statistically increased serum boron levels in experimental groups compared to healthy group. In conclusion, this study investigated the implant material produced form hBN-HA for the first time. Our data suggest that hBN is a new promising target for biomaterial and implant bioengineers. Copyright © 2015 Elsevier B.V. All rights reserved.

Boronic species as promising inhibitors of the Staphylococcus aureus NorA efflux pump: study of 6-substituted pyridine-3-boronic acid derivatives.

PubMed

Fontaine, Fanny; Héquet, Arnaud; Voisin-Chiret, Anne-Sophie; Bouillon, Alexandre; Lesnard, Aurélien; Cresteil, Thierry; Jolivalt, Claude; Rault, Sylvain

2015-05-05

In response to the extensive use of antibiotics, bacteria have evolved numerous mechanisms of defense against antimicrobial agents. Among them, extrusion of the antimicrobial agents outside the bacterial cell through efflux pumps is a major cause of concern. At first limited to one or few structurally-related antibiotics, bacterial resistance have then progressed towards cross-resistance between different classes of antibiotics, leading to multidrug-resistant microorganisms. Emergence of these pathogens requires development of novel therapeutic strategies and inhibition of efflux pumps appears to be a promising strategy that could restore the potency of existing antibiotics. NorA is the most studied chromosomal efflux pump of Staphylococcus aureus; it is known to be implied in resistance of Methicillin-resistant S. aureus (MRSA) strains against a wide range of unrelated substrates, including hydrophilic fluoroquinolones. Starting from 6-benzyloxypyridine-3-boronic acid I that we previously identified as a potential inhibitor of the NorA efflux pump against the NorA-overexpressing S. aureus 1199B strain (SA1199B), we describe here the synthesis and biological evaluation of a series of 6-(aryl)alkoxypyridine-3-boronic acids. 6-(3-Phenylpropoxy)pyridine-3-boronic acid 3i and 6-(4-phenylbutoxy)pyridine-3-boronic acid 3j were found to potentiate ciprofloxacin activity by a 4-fold increase compared to the parent compound I. In addition, it has been shown that both compounds promote Ethidium Bromide (EtBr) accumulation in SA1199B, thus corroborating their potential mode of action as NorA inhibitors. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Azomethine H colorimetric method for determining dissolved boron in water

USGS Publications Warehouse

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

1979-01-01

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

Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B{sub 6}O, B{sub 13}C{sub 2}, and B{sub 4}C, and their mixing thermodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ektarawong, A., E-mail: anekt@ifm.liu.se; Hultman, L.; Birch, J.

The elastic properties of alloys between boron suboxide (B{sub 6}O) and boron carbide (B{sub 13}C{sub 2}), denoted by (B{sub 6}O){sub 1−x}(B{sub 13}C{sub 2}){sub x}, as well as boron carbide with variable carbon content, ranging from B{sub 13}C{sub 2} to B{sub 4}C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B{sub 6}O){sub 1−x}(B{sub 13}C{sub 2}){sub x} is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic propertiesmore » calculations demonstrate that configurational disorder in B{sub 13}C{sub 2}, where a part of the C atoms in the CBC chains substitute for B atoms in the B{sub 12} icosahedra, drastically increase the Young’s and shear modulus, as compared to an atomically ordered state, B{sub 12}(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B{sub 4}C to B{sub 13}C{sub 2}. The elastic moduli of the (B{sub 6}O){sub 1−x}(B{sub 13}C{sub 2}){sub x} system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B{sub 6}O){sub 1−x}(B{sub 13}C{sub 2}){sub x}. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B{sub 6}O-rich as well as ordered or disordered B{sub 13}C{sub 2}-rich domains in the material prepared through equilibrium routes is predicted.« less

Phenylene bridged boron-nitrogen containing dendrimers.

PubMed

Proń, Agnieszka; Baumgarten, Martin; Müllen, Klaus

2010-10-01

The synthesis and characterization of novel phenylene bridged boron-nitrogen containing π-conjugated dendrimers N3B6 and N3B3, with peripheral boron atoms and 1,3,5-triaminobenzene moiety as a core, are presented. UV-vis absorption and emission measurements reveal that the optical properties of the resulting compounds can be controlled by changing the donor/acceptor ratio: a 1:1 ratio results in a more efficient charge transfer than the 1:2 ratio. This was proven by the red shift of the emission maxima and the stronger solvatochromic effect in N3B3 compared to N3B6.

Effect of hypoeutectic boron additions on the grain size and mechanical properties of Ti-6Al-4V manufactured with powder bed electron beam additive manufacturing

DOE PAGES

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola; ...

2016-12-02

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricatedmore » Ti-6Al-4V + B indicate that the addition of 0.25–1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Furthermore, despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.« less

Effect of hypoeutectic boron additions on the grain size and mechanical properties of Ti-6Al-4V manufactured with powder bed electron beam additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahbooba, Zaynab; West, Harvey; Harrysson, Ola

In additive manufacturing, microstructural control is feasible via processing parameter alteration. However, the window for parameter variation for certain materials, such as Ti-6Al-4V, is limited, and alternative methods must be employed to customize microstructures. Grain refinement and homogenization in cast titanium alloys has been demonstrated through the addition of hypoeutectic concentrations of boron. This work explores the influence of 0.00 wt.%, 0.25 wt.%, 0.50 wt.%, and 1.0 wt.% boron additions on the microstructure and bulk mechanical properties of Ti-6Al-4V samples fabricated in an Arcam A2 electron beam melting (EBM) system with commercial processing parameters for Ti-6Al-4V. Analyses of EBM fabricatedmore » Ti-6Al-4V + B indicate that the addition of 0.25–1.0 wt.% boron progressively refines the grain structure, and it improves hardness and elastic modulus. Furthermore, despite a reduction in size, the β grain structure remained columnar as a result of directional heat transfer during EBM fabrication.« less

Growth of boron doped hydrogenated nanocrystalline cubic silicon carbide (3C-SiC) films by Hot Wire-CVD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawbake, Amit; Tata Institute of Fundamental Research, Colaba, Mumbai 400 005; Mayabadi, Azam

Highlights: • Boron doped nc-3C-SiC films prepared by HW-CVD using SiH{sub 4}/CH{sub 4}/B{sub 2}H{sub 6}. • 3C-Si-C films have preferred orientation in (1 1 1) direction. • Introduction of boron into SiC matrix retard the crystallanity in the film structure. • Film large number of SiC nanocrystallites embedded in the a-Si matrix. • Band gap values, E{sub Tauc} and E{sub 04} (E{sub 04} > E{sub Tauc}) decreases with increase in B{sub 2}H{sub 6} flow rate. - Abstract: Boron doped nanocrystalline cubic silicon carbide (3C-SiC) films have been prepared by HW-CVD using silane (SiH{sub 4})/methane (CH{sub 4})/diborane (B{sub 2}H{sub 6}) gasmore » mixture. The influence of boron doping on structural, optical, morphological and electrical properties have been investigated. The formation of 3C-SiC films have been confirmed by low angle XRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FTIR) spectroscopy and high resolution-transmission electron microscopy (HR-TEM) analysis whereas effective boron doping in nc-3C-SiC have been confirmed by conductivity, charge carrier activation energy, and Hall measurements. Raman spectroscopy and HR-TEM analysis revealed that introduction of boron into the SiC matrix retards the crystallanity in the film structure. The field emission scanning electron microscopy (FE-SEM) and non contact atomic force microscopy (NC-AFM) results signify that 3C-SiC film contain well resolved, large number of silicon carbide (SiC) nanocrystallites embedded in the a-Si matrix having rms surface roughness ∼1.64 nm. Hydrogen content in doped films are found smaller than that of un-doped films. Optical band gap values, E{sub Tauc} and E{sub 04} decreases with increase in B{sub 2}H{sub 6} flow rate.« less

Pharmacokinetics of Chlorin e6-Cobalt Bis(Dicarbollide) Conjugate in Balb/c Mice with Engrafted Carcinoma

PubMed Central

Volovetsky, Arthur B.; Balalaeva, Irina V.; Dudenkova, Varvara V.; Shilyagina, Natalia Yu.; Feofanov, Аlexey V.; Efremenko, Anastasija V.; Grin, Mikhail A.; Mironov, Andrey F.; Bregadze, Vladimir I.; Maslennikova, Anna V.

2017-01-01

The necessary precondition for efficient boron neutron capture therapy (BNCT) is control over the content of isotope 10B in the tumor and normal tissues. In the case of boron-containing porphyrins, the fluorescent part of molecule can be used for quantitative assessment of the boron content. Study Objective: We performed a study of the biodistribution of the chlorin e6-Cobalt bis(dicarbollide) conjugate in carcinoma-bearing Balb/c mice using ex vivo fluorescence imaging, and developed a mathematical model describing boron accumulation and release based on the obtained experimental data. Materials and Methods: The study was performed on Balb/c tumor-bearing mice (CT-26 tumor model). A solution of the chlorin e6-Cobalt bis(dicarbollide) conjugate (CCDC) was injected into the blood at a dose of 10 mg/kg of the animal’s weight. Analysis of the fluorescence signal intensity was performed at several time points by spectrofluorimetry in blood and by laser scanning microscopy in muscle, liver, and tumor tissues. The boron content in the same samples was determined by mass spectroscopy with inductively coupled plasma. Results: Analysis of a linear approximation between the fluorescence intensity and boron content in the tissues demonstrated a satisfactory value of approximation reliability with a Spearman’s rank correlation coefficient of r = 0.938, p < 0.01. The dynamics of the boron concentration change in various organs, calculated on the basis of the fluorescence intensity, enabled the development of a model describing the accumulation of the studied compound and its distribution in tissues. The obtained results reveal a high level of correspondence between the model and experimental data. PMID:29182594

Matrix Transformation in Boron Containing High-Temperature Co-Re-Cr Alloys

NASA Astrophysics Data System (ADS)

Strunz, Pavel; Mukherji, Debashis; Beran, Přemysl; Gilles, Ralph; Karge, Lukas; Hofmann, Michael; Hoelzel, Markus; Rösler, Joachim; Farkas, Gergely

2018-03-01

An addition of boron largely increases the ductility in polycrystalline high-temperature Co-Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ɛ (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co-17Re-23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ɛ to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co-17Re-23Cr-1.2Ta-2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0-1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content.

Boron delivery with liposomes for boron neutron capture therapy (BNCT): biodistribution studies in an experimental model of oral cancer demonstrating therapeutic potential.

PubMed

Heber, Elisa M; Kueffer, Peter J; Lee, Mark W; Hawthorne, M Frederick; Garabalino, Marcela A; Molinari, Ana J; Nigg, David W; Bauer, William; Hughes, Andrea Monti; Pozzi, Emiliano C C; Trivillin, Verónica A; Schwint, Amanda E

2012-05-01

Boron neutron capture therapy (BNCT) combines selective accumulation of (10)B carriers in tumor tissue with subsequent neutron irradiation. We previously demonstrated the therapeutic efficacy of BNCT in the hamster cheek pouch oral cancer model. Optimization of BNCT depends largely on improving boron targeting to tumor cells. Seeking to maximize the potential of BNCT for the treatment for head and neck cancer, the aim of the present study was to perform boron biodistribution studies in the oral cancer model employing two different liposome formulations that were previously tested for a different pathology, i.e., in experimental mammary carcinoma in BALB/c mice: (1) MAC: liposomes incorporating K[nido-7-CH(3)(CH(2))(15)-7,8-C(2)B(9)H(11)] in the bilayer membrane and encapsulating a hypertonic buffer, administered intravenously at 6 mg B per kg body weight, and (2) MAC-TAC: liposomes incorporating K[nido-7-CH(3)(CH(2))(15)-7,8-C(2)B(9)H(11)] in the bilayer membrane and encapsulating a concentrated aqueous solution of the hydrophilic species Na(3) [ae-B(20)H(17)NH(3)], administered intravenously at 18 mg B per kg body weight. Samples of tumor, precancerous and normal pouch tissue, spleen, liver, kidney, and blood were taken at different times post-administration and processed to measure boron content by inductively coupled plasma mass spectrometry. No ostensible clinical toxic effects were observed with the selected formulations. Both MAC and MAC-TAC delivered boron selectively to tumor tissue. Absolute tumor values for MAC-TAC peaked to 66.6 ± 16.1 ppm at 48 h and to 43.9 ± 17.6 ppm at 54 h with very favorable ratios of tumor boron relative to precancerous and normal tissue, making these protocols particularly worthy of radiobiological assessment. Boron concentration values obtained would result in therapeutic BNCT doses in tumor without exceeding radiotolerance in precancerous/normal tissue at the thermal neutron facility at RA-3.

Boron delivery with liposomes for boron neutron capture therapy (BNCT): biodistribution studies in an experimental model of oral cancer demonstrating therapeutic potential

DOE Office of Scientific and Technical Information (OSTI.GOV)

David W. Nigg

2012-05-01

Boron neutron capture therapy (BNCT) combines selective accumulation of 10B carriers in tumor tissue with subsequent neutron irradiation. We previously demonstrated the therapeutic efficacy of BNCT in the hamster cheek pouch oral cancer model. Optimization of BNCT depends largely on improving boron targeting to tumor cells. Seeking to maximize the potential of BNCT for the treatment for head and neck cancer, the aim of the present study was to perform boron biodistribution studies in the oral cancer model employing two different liposome formulations that were previously tested for a different pathology, i.e., in experimental mammary carcinoma in BALB/c mice: (1)more » MAC: liposomes incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer membrane and encapsulating a hypertonic buffer, administered intravenously at 6 mg B per kg body weight, and (2) MAC-TAC: liposomes incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer membrane and encapsulating a concentrated aqueous solution of the hydrophilic species Na3 [ae-B20H17NH3], administered intravenously at 18 mg B per kg body weight. Samples of tumor, precancerous and normal pouch tissue, spleen, liver, kidney, and blood were taken at different times post-administration and processed to measure boron content by inductively coupled plasma mass spectrometry. No ostensible clinical toxic effects were observed with the selected formulations. Both MAC and MAC-TAC delivered boron selectively to tumor tissue. Absolute tumor values for MAC-TAC peaked to 66.6 {+-} 16.1 ppm at 48 h and to 43.9 {+-} 17.6 ppm at 54 h with very favorable ratios of tumor boron relative to precancerous and normal tissue, making these protocols particularly worthy of radiobiological assessment. Boron concentration values obtained would result in therapeutic BNCT doses in tumor without exceeding radiotolerance in precancerous/normal tissue at the thermal neutron facility at RA-3.« less

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

PubMed

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

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 6.0 mA/cm(2), initial boron concentration 100mg/L and solution temperature 293 K. 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; [formula in text]. 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.

Neutron Detection using Amorphous Boron-Carbide Hetero-Junction Diodes

DTIC Science & Technology

2012-03-22

Parameter Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 B.1.1 UMKC Built-in Voltage...Electronic properties of boron carbide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2. Diode Material/Geometric Parameters ...42 6. Material parameters for Davinci model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 x List of

Reproductive toxicity parameters and biological monitoring in occupationally and environmentally boron-exposed persons in Bandirma, Turkey.

PubMed

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.

Boron and silicon: Effects on growth, plasma lipids, urinary cyclic AMP and bone and brain mineral composition of male rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seaborn, C.D.; Nielsen, F.H.

1994-06-01

Because boron resembles silicon in its chemical properties, an experiment was performed to determine if excessive dietary boron would affect the response to silicon deprivation and, conversely, if silicon would influence the effects of an excessive intake of boron. Male weanling Sprague-Dawley rats were assigned to groups of 6 or 12 in a two-by-two factorially arranged experiment. Supplemented to a ground corn/casein diet containing 1.2 [mu]g silicon and 3 [mu]g boron per gram were silicon as sodium metasilicate at 0 or 50 [mu]g/g and boron as orthoboric acid at 0 or 500 [mu]g/g diet. At nine weeks, animals fed highmore » dietary boron had significantly decreased final body weights, liver-weight-to-body-weight ratios, urinary cAMP concentrations, plasma triglyceride, cholesterol, glycine, valine, leucine, and lysine concentrations and skull copper, sodium, and manganese concentrations. High dietary boron also significantly increased brain-weight-to-body-weight ratios, magnesium concentrations of femur, brain, and plasma, zinc concentration of femur, and iron concentration of skull. The bone mineral findings suggest that excess dietary boron exerts subtle effects on bone composition. Dietary silicon affected blood urea nitrogen, hematocrit, hemoglobin, and the concentrations of plasma threonine and aspartic acid in animals fed excess boron. Depression of the testes-weight-to-body-weight ratio of animals fed 500 [mu]g boron per gram diet was most marked in animals not fed silicon. Although excessive dietary boron did not markedly enhanced the response of rats to silicon deprivation, dietary silicon affected their response to high dietary boron. Thus, dietary silicon apparently can influence boron toxicity.« less

Predicting the structural and electronic properties of two-dimensional single layer boron nitride sheets

NASA Astrophysics Data System (ADS)

Li, Xiao-Dong; Cheng, Xin-Lu

2018-02-01

Three two-dimensional (2D) single layer boron nitride sheets have been predicted based on the first-principles calculations. These 2D boron nitride sheets are comprised of equivalent boron atoms and nitride atoms with sp2 and sp bond hybridization. The geometry optimization reflects that they all possess stable planar crystal structures with the space group P 6 bar 2 m (D3h3) symmetry. The charge density distribution manifests that the B-N bonds in these boron nitride sheets are covalent in nature but with ionic characteristics. The tunable band gaps indicate their potential applications in nanoscale electronic and optoelectronic devices by changing the length of sp-bonded Bsbnd N linkages.

Priority compositions of boron carbide crystals obtained by self-propagating high-temperature synthesis

NASA Astrophysics Data System (ADS)

Ponomarev, V. I.; Konovalikhin, S. V.; Kovalev, I. D.; Vershinnikov, V. I.

2015-09-01

Splitting of reflections from boron carbide has been found for the first time by an X-ray diffraction study of polycrystalline mixture of boron carbide В15- х С х , (1.5 ≤ x ≤ 3) and its magnesium derivative C4B25Mg1.42. An analysis of reflection profiles shows that this splitting is due to the presence of boron carbide phases of different compositions in the sample, which are formed during crystal growth. The composition changes from В12.9С2.1 to В12.4С2.6.

Interaction of Boron Clusters with Oxygen: a DFT Study

NASA Astrophysics Data System (ADS)

Salavitabar, Kamron; Boggavarapu, Kiran; Kandalam, Anil

A controlled combustion involving aluminum nanoparticles has often been the focus of studies in the field of solid fuel propellants. However very little focus has been given to the study of boron nanoparticles in controlled combustion. In contrast to aluminum nanoclusters, boron nanoclusters (Bn) are known to exhibit a planar geometries even at the size of n = 19 - 20, and thus offer a greater surface area for interaction with oxygen. Earlier experimental studies have shown that boron nanoclusters exhibit different reactivity with oxygen depending on their size and charge. In this poster, we present our recent density functional theory based results, focusing on the reactivity patterns of neutral and negatively charged B5 cluster with On, where n = 1 - 5; and B6 cluster with On (n = 1 - 2). The effect of charge on the reactivity of boron cluster, variation in the stability of product clusters, i e., neutral and negatively charged B5On (n = 1 - 5) and B6On (n = 1 - 2) are also examined. Financial Support from West Chester University Foundation under FaStR grant is acknowledged.

Effect of Gd2O3 doping on structure and boron volatility of borosilicate glass sealants in solid oxide fuel cells-A study on the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode

NASA Astrophysics Data System (ADS)

Zhang, Qi; Tan, Shengwei; Ren, Mengyuan; Yang, Hsiwen; Tang, Dian; Chen, Kongfa; Zhang, Teng; Jiang, San Ping

2018-04-01

Boron volatility is one of the most important properties of borosilicate-based glass sealants in solid oxide fuel cells (SOFCs), as boron contaminants react with lanthanum-containing cathodes, forming LaBO3 and degrading the activity of SOFCs. Here, we report that the reaction between the volatile boron and a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode during polarization can be significantly reduced by doping aluminoborosilicate glass with Gd2O3. Specifically, the Gd cations in glass with 2 mol.% Gd2O3 dissolve preferentially in the borate-rich environment to form more Gd-metaborate structures and promote the formation of calcium metaborate (CaB2O4); they also condense the B-O network after heat treatment, which suppresses poisoning by boron contaminants on the LSCF cathode. The results provide insights into design and development of a reliable sealing glass for SOFC applications.

Materials for high-temperature thermoelectric conversion

NASA Technical Reports Server (NTRS)

Feigelson, R. S.; Elwell, D.

1983-01-01

High boron materials of high efficiency for thermoelectric power generation and capable of prolonged operation at temperatures over 1200 C are discussed. Background theoretical studies indicated that the low carrier mobility of materials with beta boron and related structures is probably associated with the high density of traps. Experimental work was mainly concerned with silicon borides in view of promising data from European laboratories. A systematic study using structure determination and lattice constant measurements failed to confirm the existence of an SiBn phase. Only SiB6 and a solid solution of silicon in beta boron with a maximum solid solubility of 5.5-6 at % at 1650 C were found.

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

PubMed

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

2015-12-01

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

The Combined Action of Duplicated Boron Transporters Is Required for Maize Growth in Boron-Deficient Conditions.

PubMed

Chatterjee, Mithu; Liu, Qiujie; Menello, Caitlin; Galli, Mary; Gallavotti, Andrea

2017-08-01

The micronutrient boron is essential in maintaining the structure of plant cell walls and is critical for high yields in crop species. Boron can move into plants by diffusion or by active and facilitated transport mechanisms. We recently showed that mutations in the maize boron efflux transporter ROTTEN EAR (RTE) cause severe developmental defects and sterility. RTE is part of a small gene family containing five additional members ( RTE2 - RTE6 ) that show tissue-specific expression. The close paralogous gene RTE2 encodes a protein with 95% amino acid identity with RTE and is similarly expressed in shoot and root cells surrounding the vasculature. Despite sharing a similar function with RTE , mutations in the RTE2 gene do not cause growth defects in the shoot, even in boron-deficient conditions. However, rte2 mutants strongly enhance the rte phenotype in soils with low boron content, producing shorter plants that fail to form all reproductive structures. The joint action of RTE and RTE2 is also required in root development. These defects can be fully complemented by supplying boric acid, suggesting that diffusion or additional transport mechanisms overcome active boron transport deficiencies in the presence of an excess of boron. Overall, these results suggest that RTE2 and RTE function are essential for maize shoot and root growth in boron-deficient conditions. Copyright © 2017 by the Genetics Society of America.

Advanced Design Composite Aircraft (ADCA) Study. Volume I

DTIC Science & Technology

1976-11-01

Aluminum Machined Paits 008 ’— Aluminum Honeycomb 001 - - Steel Machined Parts 0.08 - Titanium 0 66 Fiberglass 1 18 _ Boron Composite 0...Honeycomb 001 ~ Steel Machined Parti 0 09 | Titanium 056 Fi bei glass 037 r i Boron Composite 0 Graphite Composite 6 36 Total 81 2 31 7 42 1...1 Aluminum Machined Parts 006 - 2 1 Aluminum Honeycomb 001 Steel Machined Parts 007 - Trtamum 001 1 Frberglass 029 - Boron Composite 0

First Principles Atomistic Model for Carbon-Doped Boron Suboxide

DTIC Science & Technology

2014-09-01

First Principles Atomistic Model for Carbon-Doped Boron Suboxide by Amol B Rahane, Jennifer S Dunn, and Vijay Kumar ARL-TR-7106...2014 First Principles Atomistic Model for Carbon-Doped Boron Suboxide Amol B Rahane Dr Vijay Kumar Foundation 1969 Sector 4 Gurgaon...5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Amol B Rahane, Jennifer S Dunn, and Vijay Kumar 5d. PROJECT

Functionalizing graphene by embedded boron clusters

NASA Astrophysics Data System (ADS)

Quandt, Alexander; Özdoğan, Cem; Kunstmann, Jens; Fehske, Holger

2008-08-01

We present a model system that might serve as a blueprint for the controlled layout of graphene based nanodevices. The systems consists of chains of B7 clusters implanted in a graphene matrix, where the boron clusters are not directly connected. We show that the graphene matrix easily accepts these alternating B7-C6 chains and that the implanted boron components may dramatically modify the electronic properties of graphene based nanomaterials. This suggests a functionalization of graphene nanomaterials, where the semiconducting properties might be supplemented by parts of the graphene matrix itself, but the basic wiring will be provided by alternating chains of implanted boron clusters that connect these areas.

One-Step Borylation of 1,3-Diaryloxybenzenes Towards Efficient Materials for Organic Light-Emitting Diodes.

PubMed

Hirai, Hiroki; Nakajima, Kiichi; Nakatsuka, Soichiro; Shiren, Kazushi; Ni, Jingping; Nomura, Shintaro; Ikuta, Toshiaki; Hatakeyama, Takuji

2015-11-09

The development of a one-step borylation of 1,3-diaryloxybenzenes, yielding novel boron-containing polycyclic aromatic compounds, is reported. The resulting boron-containing compounds possess high singlet-triplet excitation energies as a result of localized frontier molecular orbitals induced by boron and oxygen. Using these compounds as a host material, we successfully prepared phosphorescent organic light-emitting diodes exhibiting high efficiency and adequate lifetimes. Moreover, using the present one-step borylation, we succeeded in the synthesis of an efficient, thermally activated delayed fluorescence emitter and boron-fused benzo[6]helicene. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Processing and characterization of boron carbide-hafnium diboride ceramics

NASA Astrophysics Data System (ADS)

Brown-Shaklee, Harlan James

Hafnium diboride based ceramics are promising candidate materials for advanced aerospace and nuclear reactor components. The effectiveness of boron carbide and carbon as HfB2 sintering additives was systematically evaluated. In the first stage of the research, boron carbide and carbon additives were found to improve the densification behavior of milled HfB2 powder in part by removing oxides at the HfB2 surface during processing. Boron carbide additives reduced the hot pressing temperature of HfB2 by 150°C compared to carbon, which reduced the hot pressing temperature by ˜50°C. Reduction of oxide impurities alone could not explain the difference in sintering enhancement, however, and other mechanisms of enhancement were evaluated. Boron carbides throughout the homogeneity range were characterized to understand other mechanisms of sintering enhancement in HfB2. Heavily faulted carbon rich and boron rich boron carbides were synthesized for addition to HfB2. The greatest enhancement to densification was observed in samples containing boron- and carbon-rich compositions whereas B6.5 C provided the least enhancement to densification. It is proposed that carbon rich and boron rich boron carbides create boron and hafnium point defects in HfB2, respectively, which facilitate densification. Evaluation of the thermal conductivity (kth) between room temperature and 2000°C suggested that the stoichiometry of the boron carbide additives did not significantly affect kth of HfB2-BxC composites. The improved sinterability and the high kth (˜110 W/m-K at 300K and ˜90 W/m-K at 1000°C ) of HfB2-BxC ceramics make them excellent candidates for isotopically enriched reactor control materials.

Impact resistant boron/aluminum composites for large fan blades

NASA Technical Reports Server (NTRS)

Oller, T. L.; Salemme, C. T.; Bowden, J. H.; Doble, G. S.; Melnyk, P.

1977-01-01

Blade-like specimens were subjected to static ballistic impact testing to determine their relative FOD impact resistance levels. It was determined that a plus or minus 15 deg layup exhibited good impact resistance. The design of a large solid boron/aluminum fan blade was conducted based on the FOD test results. The CF6 fan blade was used as a baseline for these design studies. The solid boron/aluminum fan blade design was used to fabricate two blades. This effort enabled the assessment of the scale up of existing blade manufacturing details for the fabrication of a large B/Al fan blade. Existing CF6 fan blade tooling was modified for use in fabricating these blades.

Stability and molecular properties of the boron-nitrogen alternating analogs of azulene and naphthalene: a computational study.

PubMed

Catão, Anderson José Lopes; López-Castillo, Alejandro

2017-04-01

In this work, the spectroscopic information, stability and aromaticity of the boron-nitrogen azulene and naphthalene molecules are provided by the use of CC2 (geometry optimization, dipole moment, UV-vis spectrum calculations) and DFT (vibrational spectrum and NMR calculations) methodologies. One isomer of the investigated boron-nitrogen naphthalene (boroazanaphthalene) and two isomers of boron-nitrogen azulene, 1,3,4,6,8-pentaaza-2,3a,5,7,8a-pentaboraazulene (BN-azulene) and 2,3a,5,7,8a-pentaaza-1,3,4,6,8- pentaboraazulene (NB-azulene), are stable systems. However, these molecules have different properties, i.e., different stability, dipole moment, and aromaticity based on the NICS approach. BN-naphthalene has a high dipole moment magnitude showing high polar character, while naphthalene is apolar. BN- and NB-azulene are weakly polar, while ordinary azulene is highly polar in character. Also, substitution of C atoms by B and N atoms decreases the aromaticity. In the case of NB-azulene, the seven-membered ring has anti-aromaticity behavior while both rings of BN-azulene exhibit aromaticity. We expect that the new theoretical data provided in this work will be useful in identifying and characterizing experimentally the compounds investigated, and in helping our understanding of the chemistry of boron-nitrogen molecules. Graphical abstract Boron-nitrogen alternating analogs of azulene. Spectral distinction between isomers.

A cavity ring-down spectroscopy sensor for real-time Hall thruster erosion measurements.

PubMed

Lee, B C; Huang, W; Tao, L; Yamamoto, N; Gallimore, A D; Yalin, A P

2014-05-01

A continuous-wave cavity ring-down spectroscopy sensor for real-time measurements of sputtered boron from Hall thrusters has been developed. The sensor uses a continuous-wave frequency-quadrupled diode laser at 250 nm to probe ground state atomic boron sputtered from the boron nitride insulating channel. Validation results from a controlled setup using an ion beam and target showed good agreement with a simple finite-element model. Application of the sensor for measurements of two Hall thrusters, the H6 and SPT-70, is described. The H6 was tested at power levels ranging from 1.5 to 10 kW. Peak boron densities of 10 ± 2 × 10(14) m(-3) were measured in the thruster plume, and the estimated eroded channel volume agreed within a factor of 2 of profilometry. The SPT-70 was tested at 600 and 660 W, yielding peak boron densities of 7.2 ± 1.1 × 10(14) m(-3), and the estimated erosion rate agreed within ~20% of profilometry. Technical challenges associated with operating a high-finesse cavity in the presence of energetic plasma are also discussed.

Characteristic Study of Boron Doped Carbon Nanowalls Films Deposited by Microwave Plasma Enhanced Chemical Vapor Deposition.

PubMed

Lu, Chunyuan; Dong, Qi; Tulugan, Kelimu; Park, Yeong Min; More, Mahendra A; Kim, Jaeho; Kim, Tae Gyu

2016-02-01

In this research, catalyst-free vertically aligned boron doped carbon nanowalls films were fabricated on silicon (100) substrates by MPECVD using feeding gases CH4, H2 and B2H6 (diluted with H2 to 5% vol) as precursors. The substrates were pre-seeded with nanodiamond colloid. The fabricated CNWs films were characterized by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The data obtained from SEM confirms that the CNWs films have different density and wall thickness. From Raman spectrum, a G peak around 1588 cm(-1) and a D band peak at 1362 cm(-1) were observed, which indicates a successful fabrication of CNWs films. The EDX spectrum of boron doped CNWs film shows the existence of boron and carbon. Furthermore, field emission properties of boron doped carbon nanowalls films were measured and field enhancement factor was calculated using Fowler-Nordheim plot. The result indicates that boron doped CNWs films could be potential electron emitting materials.

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

NASA Astrophysics Data System (ADS)

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

2016-09-01

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

Layer speciation and electronic structure investigation of freestanding hexagonal boron nitride nanosheets

NASA Astrophysics Data System (ADS)

WangEqual Contribution To This Work., Jian; Wang, Zhiqiang; Cho, Hyunjin; Kim, Myung Jong; Sham, T. K.; Sun, Xuhui

2015-01-01

Chemical imaging, thickness mapping, layer speciation and polarization dependence have been performed on single and multilayered (up to three layers and trilayered nanosheets overlapping to form 6 and 9 layers) hexagonal boron nitride (hBN) nanosheets by scanning transmission X-ray microscopy. Spatially-resolved XANES directly from freestanding regions of different layers has been extracted and compared with sample normal and 30° tilted configurations. Notably a double feature σ* excitonic state and a stable high energy σ* state were observed at the boron site in addition to the intense π* excitonic state. The boron projected σ* DOS, especially the first σ* exciton, is sensitive to surface modification, particularly in the single layered hBN nanosheet which shows more significant detectable contaminants and defects such as tri-coordinated boron/nitrogen oxide. The nitrogen site has shown very weak or no excitonic character. The distinct excitonic effect on boron and nitrogen was interpreted to the partly ionic state of hBN. Bulk XANES of hBN nanosheets was also measured to confirm the spectro-microscopic STXM result. Finally, the unoccupied electronic structures of hBN and graphene were compared.Chemical imaging, thickness mapping, layer speciation and polarization dependence have been performed on single and multilayered (up to three layers and trilayered nanosheets overlapping to form 6 and 9 layers) hexagonal boron nitride (hBN) nanosheets by scanning transmission X-ray microscopy. Spatially-resolved XANES directly from freestanding regions of different layers has been extracted and compared with sample normal and 30° tilted configurations. Notably a double feature σ* excitonic state and a stable high energy σ* state were observed at the boron site in addition to the intense π* excitonic state. The boron projected σ* DOS, especially the first σ* exciton, is sensitive to surface modification, particularly in the single layered hBN nanosheet which shows more significant detectable contaminants and defects such as tri-coordinated boron/nitrogen oxide. The nitrogen site has shown very weak or no excitonic character. The distinct excitonic effect on boron and nitrogen was interpreted to the partly ionic state of hBN. Bulk XANES of hBN nanosheets was also measured to confirm the spectro-microscopic STXM result. Finally, the unoccupied electronic structures of hBN and graphene were compared. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04445b

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahl, S.B.

Although significant progress toward the application of boronated LDL for site selective boron drug delivery has been made during the past year, the loss of our animal and cell culture testing site at WSU has seriously hampered progress on this project. Results are reported of one in vivo biodistribution study in B16BL6-bearing mice and a series of in vitro studies that demonstrate very substantial uptake of boronated LDL in certain cell lines. The influence of 17{alpha}-ethinyl estradiol (EE) on cellular uptake has also been probed. Most significantly LDL loaded with HC was demonstrated to be taken up with exceptional ariditymore » in several lines. Significant progress has also been made in the development of a rapid infrared analysis of boron in boronated LDL solution, which may be useful for clinical BNCT studies in Finland.« less

Boron neutron capture therapy demonstrated in mice bearing EMT6 tumors following selective delivery of boron by rationally designed liposomes

PubMed Central

Kueffer, Peter J.; Maitz, Charles A.; Khan, Aslam A.; Schuster, Seth A.; Shlyakhtina, Natalia I.; Jalisatgi, Satish S.; Brockman, John D.; Nigg, David W.; Hawthorne, M. Frederick

2013-01-01

The application of boron neutron capture therapy (BNCT) following liposomal delivery of a 10B-enriched polyhedral borane and a carborane against mouse mammary adenocarcinoma solid tumors was investigated. Unilamellar liposomes with a mean diameter of 134 nm or less, composed of an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine and incorporating Na3[1-(2′-B10H9)-2-NH3B10H8] in the aqueous interior and K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the bilayer, were injected into the tail veins of female BALB/c mice bearing right flank EMT6 tumors. Biodistribution studies indicated that two identical injections given 24 h apart resulted in tumor boron levels exceeding 67 µg/g tumor at 54 h—with tumor/blood boron ratios being greatest at 96 h (5.68:1; 43 µg boron/g tumor)—following the initial injection. For BNCT experiments, tumor-bearing mice were irradiated 54 h after the initial injection for 30 min with thermal neutrons, resulting in a total fluence of 1.6 × 1012 neutrons per cm2 (±7%). Significant suppression of tumor growth was observed in mice given BNCT vs. control mice (only 424% increase in tumor volume at 14 d post irradiation vs. 1551% in untreated controls). In a separate experiment in which mice were given a second injection/irradiation treatment 7 d after the first, the tumor growth was vastly diminished (186% tumor volume increase at 14 d). A similar response was obtained for mice irradiated for 60 min (169% increase at 14 d), suggesting that neutron fluence was the limiting factor controlling BNCT efficacy in this study. PMID:23536304

Validation and Comparison of the Therapeutic Efficacy of Boron Neutron Capture Therapy Mediated By Boron-Rich Liposomes in Multiple Murine Tumor Models

DOE PAGES

Maitz, Charles A.; Khan, Aslam A.; Kueffer, Peter J.; ...

2017-08-01

Boron neutron capture therapy (BNCT) was performed at the University of Missouri Research Reactor in mice bearing CT26 colon carcinoma flank tumors and the results were compared with previously performed studies with mice bearing EMT6 breast cancer flank tumors. We implanted mice with CT26 tumors subcutaneously in the caudal flank and were given two separate tail vein injections of unilamellar liposomes composed of cholesterol, 1,2-distearoyl-sn-glycer-3-phosphocholine, and K[nido-7-CH 3(CH 2) 15–7,8-C 2B 9H 11] in the lipid bilayer and encapsulated Na 3[1-(2`-B 10H 9)-2-NH 3B 10H 8] within the liposomal core. Mice were irradiated 30 hours after the second injection inmore » a thermal neutron beam for various lengths of time. The tumor size was monitored daily for 72 days. In spite of relatively lower tumor boron concentrations, as compared to EMT6 tumors, a 45 minute neutron irradiation BNCT resulted in complete resolution of the tumors in 50% of treated mice, 50% of which never recurred. Median time to tumor volume tripling was 38 days in BNCT treated mice, 17 days in neutron-irradiated mice given no boron compounds, and 4 days in untreated controls. Tumor response in mice with CT26 colon carcinoma was markedly more pronounced than in previous reports of mice with EMT6 tumors, a difference which increased with dose. The slope of the dose response curve of CT26 colon carcinoma tumors is 1.05 times tumor growth delay per Gy compared to 0.09 times tumor growth delay per Gy for EMT6 tumors, indicating that inherent radiosensitivity of tumors plays a role in boron neutron capture therapy and should be considered in the development of clinical applications of BNCT in animals and man.« less

Validation and Comparison of the Therapeutic Efficacy of Boron Neutron Capture Therapy Mediated By Boron-Rich Liposomes in Multiple Murine Tumor Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maitz, Charles A.; Khan, Aslam A.; Kueffer, Peter J.

Boron neutron capture therapy (BNCT) was performed at the University of Missouri Research Reactor in mice bearing CT26 colon carcinoma flank tumors and the results were compared with previously performed studies with mice bearing EMT6 breast cancer flank tumors. We implanted mice with CT26 tumors subcutaneously in the caudal flank and were given two separate tail vein injections of unilamellar liposomes composed of cholesterol, 1,2-distearoyl-sn-glycer-3-phosphocholine, and K[nido-7-CH 3(CH 2) 15–7,8-C 2B 9H 11] in the lipid bilayer and encapsulated Na 3[1-(2`-B 10H 9)-2-NH 3B 10H 8] within the liposomal core. Mice were irradiated 30 hours after the second injection inmore » a thermal neutron beam for various lengths of time. The tumor size was monitored daily for 72 days. In spite of relatively lower tumor boron concentrations, as compared to EMT6 tumors, a 45 minute neutron irradiation BNCT resulted in complete resolution of the tumors in 50% of treated mice, 50% of which never recurred. Median time to tumor volume tripling was 38 days in BNCT treated mice, 17 days in neutron-irradiated mice given no boron compounds, and 4 days in untreated controls. Tumor response in mice with CT26 colon carcinoma was markedly more pronounced than in previous reports of mice with EMT6 tumors, a difference which increased with dose. The slope of the dose response curve of CT26 colon carcinoma tumors is 1.05 times tumor growth delay per Gy compared to 0.09 times tumor growth delay per Gy for EMT6 tumors, indicating that inherent radiosensitivity of tumors plays a role in boron neutron capture therapy and should be considered in the development of clinical applications of BNCT in animals and man.« less

Research in Energetic Compounds

DTIC Science & Technology

1983-01-01

with hypochlorous acid gave a chlorohydrocarbon, but reaction of the dioxime with chlorine gave 2,6-dichloro-2.6-dinitrosobicyclo[3.3.1)- non&ne. This...Catalyst Concentration on Yield . .3 III. Effect of Monomer Concentration on Yield... 4 IV. Boron Trifluoride and I.q-Butanedzol Catalysis. o V...from 3-azidooxetane with catalysis by boron trifluoride •4 etherate. A problem with this polymerization was that yields were generally in the 50

Temperature Dependence of Gas Properties in Polynomial Form

DTIC Science & Technology

1981-01-01

Carbonyl Sulfide Chlorine Chlorine (Monatomic) Chlorine Dioxide Chlorine Fluoride Chlorine Monoxide Chlorine Oxide Chlorine Trifluoride ...dis- cussed in Section 5 and the following eqn: 100-1500K~ Cp(T)= 515.3754 + 0.426933T -2.91036E-04T 2 -+ 6.836113E-08Ti CHLORINE TRIFLUORIDE C1F 3...3 Trimeric Boron Tribromide BBr3 250.538 33.186 A-3 Boron Trichloride BC1 3 117.170 70.959 A-4 Boron Trifluoride BF3 67.806 122.619 A-4 Bromine Br2

Chromium boron surfaced nickel-iron base alloys

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Repurposing Suzuki Coupling Reagents as a Directed Fragment Library Targeting Serine Hydrolases and Related Enzymes.

PubMed

Lanier, Marion; Cole, Derek C; Istratiy, Yelena; Klein, Michael G; Schwartz, Phillip A; Tjhen, Richard; Jennings, Andy; Hixon, Mark S

2017-06-22

Serine hydrolases are susceptible to potent reversible inhibition by boronic acids. Large collections of chemically diverse boronic acid fragments are commercially available because of their utility in coupling chemistry. We repurposed the approximately 650 boronic acid reagents in our collection as a directed fragment library targeting serine hydrolases and related enzymes. Highly efficient hits (LE > 0.6) often result. The utility of the approach is illustrated with the results against autotaxin, a phospholipase implicated in cardiovascular disease.

Production and Characterization of Bulk MgB2 Material made by the Combination of Crystalline and Carbon Coated Amorphous Boron Powders

NASA Astrophysics Data System (ADS)

Hiroki, K.; Muralidhar, M.; Koblischka, M. R.; Murakami, M.

2017-07-01

The object of this investigation is to reduce the cost of bulk production and in the same time to increase the critical current performance of bulk MgB2 material. High-purity commercial powders of Mg metal (99.9% purity) and two types of crystalline (99% purity) and 16.5 wt% carbon-coated, nanometer-sized amorphous boron powders (98.5% purity) were mixed in a nominal composition of MgB2 to reduce the boron cost and to see the effect on the superconducting and magnetic properties. Several samples were produced mixing the crystalline boron and carbon-coated, nanometer-sized amorphous boron powders in varying ratios (50:50, 60:40, 70:30, 80:20, 90:10) and synthesized using a single-step process using the solid state reaction around 800 °C for 3 h in pure argon atmosphere. The magnetization measurements exhibited a sharp superconducting transition temperature with T c, onset around 38.6 K to 37.2 K for the bulk samples prepared utilizing the mixture of crystalline boron and 16.5% carbon-coated amorphous boron. The critical current density at higher magnetic field was improved with addition of carbon-coated boron to crystalline boron in a ratio of 80:20. The highest self-field Jc around 215,000 A/cm2 and 37,000 A/cm2 were recorded at 20 K, self-field and 2 T for the sample with a ratio of 80:10. The present results clearly demonstrate that the bulk MgB2 performance can be improved by adding carbon-coated nano boron to crystalline boron, which will be attractive to reduce the cost of bulk MgB2 material for several industrial applications.

Large-area few-layer hexagonal boron nitride prepared by quadrupole field aided exfoliation

NASA Astrophysics Data System (ADS)

Lun Lu, Han; Zhi Rong, Min; Qiu Zhang, Ming

2018-03-01

A quadrupole electric field-mediated exfoliation method is proposed to convert micron-sized hexagonal boron nitride (h-BN) powder into few-layer hexagonal boron nitride nanosheets (h-BNNS). Under optimum conditions (400 Hz, 40 V, 32 μg ml-1, sodium deoxycholate, TAE medium), the h-BN powders (thickness >200 nm, horizontal scale ˜10 μm) are successfully exfoliated into 0.5-4 nm (1-10 layers) thick h-BNNS with the same horizontal scale. Dynamic laser scattering and atomic force microscope data show that the yield is 47.6% (for the portion with the thickness of 0.5-6 nm), and all of the vertical sizes are reduced to smaller than 18 nm (45 layers).

X-ray photoemission spectroscopy of nonmetallic materials: Electronic structures of boron and BxOy

NASA Astrophysics Data System (ADS)

Ong, C. W.; Huang, H.; Zheng, B.; Kwok, R. W. M.; Hui, Y. Y.; Lau, W. M.

2004-04-01

Although an increasing volume of x-ray photoemission spectroscopic (XPS) data has been accumulated on boron and boron-rich compounds because of their unusual properties, including a unique three-center, two-electron bonding configuration, their common nonmetallic nature has been overlooked. Typically, the measured energy-state data are not clarified by surface Fermi level positions of these nonmetallic samples, which compromises the scientific contents of the data. In the present study, we revisited the XPS studies of sputter-cleaned β-rhombohedral boron (βr-B), the oxidized surface of βr-B, B6O pellet, and polished B2O3, to illustrate the impact and resolution of this scientific issue. These samples were chosen because βr-B is the most thermodynamically stable polytype of pure boron, B2O3 is its fully oxidized form, and B6O is the best known superhard family member of boron-rich compounds. From our XPS measurements, including those from a sputter-cleaned gold as a metal reference, we deduced that our βr-B had a surface Fermi level located at 0.7±0.1 eV from its valence-band maximum (VBM) (referred as EFL) and a binding energy for its B 1s core level at 187.2 eV from VBM (Eb,VBM). The latter attribute, unlike typical XPS binding energy data that are referenced to a sample-dependent Fermi level (Eb,FL), is immune from any uncertainties and variations arising from sample doping and surface charging. For bulk B2O3, we found an Eb,VBM for its B 1s core level at 190.5 eV and an Eb,FL at 193.6 eV. For our βr-B subjected to a surface oxidation treatment, an overlayer structure of ˜1.2 nm B2O3/˜2 nm B2O/B was found. By comparing the data from this sample and those from βr-B and bulk B2O3, we infer that the oxide overlayer carried some negative fixed charge and this induced on the semiconducting βr-B sample an upward surface band bending of ˜0.6 eV. As for our B6O sample, we found an EFL of ˜1.7 eV and two different chemical states having Eb,VBM of 185.4 and 187.2 eV, with the former belonging to boron with no oxygen neighbor and the latter to boron with an oxygen neighbor. The methodology in this work is universally applicable to all nonmetallic samples.

The effect of pregnancy on renal clearance of boron in rats given boric acid orally.

PubMed

Vaziri, N D; Oveisi, F; Culver, B D; Pahl, M V; Andersen, M E; Strong, P L; Murray, F J

2001-04-01

Boric acid (H(3)BO(3)) has been shown to cause developmental abnormalities in the offspring of pregnant rats. Comparative data on the renal clearance of boron (B) in rats and humans, both pregnant and nonpregnant, exposed to boric acid (BA) would reduce uncertainty in interspecies extrapolation from rats to humans. The purpose of this study was to evaluate the effect of pregnancy on the plasma half-life and renal clearance of boron in Sprague-Dawley rats given a single oral dose of boric acid. For the half-life study, nonpregnant and pregnant (gestation day 16) rats were given a single dose of 30 mg/kg of boric acid by gavage, and plasma samples were collected at 2-3 h intervals. The plasma half-life of boron was determined to be 2.9 +/- 0.2 and 3.2 +/- 0.3 h in nonpregnant and pregnant rats, respectively. In the clearance study, nonpregnant and pregnant (GD 16) rats were given a single gavage dose of 0.3, 3, or 30 mg/kg of boric acid. Boron clearance was slightly higher in pregnant rats (3.3 +/- 0.6, 3.2 +/- 0.5, and 3.4 +/- 0.5 ml/min/kg, respectively) compared to nonpregnant rats (3.1 +/- 0.8, 3.0 +/- 0.6, and 3.2 +/- 0.5 ml/min/kg, respectively), but the difference was not statistically significant and not dose-related. Boron clearance was less than creatinine clearance, suggesting tubular reabsorption in both groups. In conclusion, pregnancy did not appear to significantly alter the renal clearance or the plasma half-life of boron in Sprague-Dawley rats under the conditions of this study.

Ignition kinetics of boron in primary combustion products of propellant based on its unique characteristics

NASA Astrophysics Data System (ADS)

Ao, Wen; Wang, Yang; Wu, Shixi

2017-07-01

Study on the boron-based primary combustion products can bridge the gap between primary combustion and secondary combustion in solid rocket ramjets. To clarify the initial state and ignition characteristics of boron particles in the after-burning chamber of solid rocket ramjets, the elemental, composition and morphology of the primary combustion products collected under gas generator chamber pressure of 0.2 MPa and 6 MPa were investigated by energy dispersive (EDS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive (SEM-EDS) individually. The ignition times of boron particles among the primary combustion products were determined using a high temperature tube furnace system. The BD model was adopted for numerical verification. The numerical solution procedure of boron ignition model in a real afterburner chamber was modified. The results show that the sum of B, C, O elements in the primary combustion products reaches approximately 90%. The primary combustion products are mainly consisted of B, C, and B2O3. Images of the primary combustion products present highly agglomeration, indicating an oxidation of boron surface. Numerous spherical carbon particles with a diameter around 100 nm are observed in the products. Three features of the boron in the primary combustion products are obtained, compared to virgin boron. First most of the boron lumps are covered by carbon particles on the surface. Second the mean particle size is five times larger than that of virgin boron. Third the overall initial oxide layer covered on boron surface increases its thickness by above 0.1 μm. The ignition time of boron in the primary combustion products reaches 20-30 ms under 1673-1873 K, which is quite different from virgin boron of 4 ms. Numerical calculation results show the key reason leading to such a long ignition time is the variation of the initial oxide layer thickness. In conclusion, the physicochemical properties of boron particles are found to differ with virgin boron after primary combustion process. The accurate evaluation of the initial oxide layer thickness and initial particle radius is a crucial procedure before the numerical calculation of boron ignition kinetics. Results of our study are expected to provide better insight in the simulation of solid rocket ramjets working process.

Assessment of environmental factors affecting male fertility

PubMed Central

Dixon, R. L.; Sherins, R. J.; Lee, I. P.

1979-01-01

Exposure to drinking water containing as much as 500 ppm aluminum chloride for periods of 30, 60, and 90 days had no apparent effect on male reproductive processes. In an attempt to correlate enzyme activity with particular spermatogenic cell types, postnatal development of testicular enzymes was studied. Eight enzymes were selected: hyaluronidase (H), lactate dehydrogenase isoenzyme-X (LDH-X), dehydrogenases of sorbitol (SDH), α-glycerophosphate (GPDH), glucose-6-phosphate (G6PDH), malate (MDH), glyceraldehyde-3-phosphate (G3PDH), and isocitrate (ICDH). Enzyme specific activities in testicular homogenates were determined. Two types of enzyme developmental patterns were observed. One was represented by H, LDH-X, SDH, and GPDH; and the other by G6PDH, MDH, G3PDH, and ICDH. The former was characterized by a change in enzyme activities from low in newborn to high in adult while in the latter this pattern was reversed. The two complementary enzyme systems crossed each other at puberty. Prior to puberty, only spermatogonial cells are present; sperm differentiation initiated at puberty adds spermatocytes and spermatids to the testicular cell population. Male rats were exposed to borax in their diet for periods of 30 and 60 days. Concentrations of boron were 0, 500, 1000, and 2000 ppm. At the end of each experimental period, the specific activities of the selected enzymes were determined in the testis and prostate. Correlations of enzyme activity with testicular histology and androgen activities of the male accessory organs were sought. In addition, plasma FSH, LH, and testosterone levels were measured to assess pituitary-testicular interaction. Plasma and testicular boron concentrations were determined and a minimum boron concentration which induced germinal aplasia and male infertility was estimated. In both 30 and 60 day feeding studies, male rats receiving 500 ppm failed to demonstrate any significant adverse effects. In contrast, male rats receiving 100 and 2000 ppm boron displayed a significant loss of germinal elements, although most of the Leydig and Sertoli cells appeared normal. Testicular atrophy was associated with a decrease in seminiferous tubular diameter and a marked reduction of spermatocytes and spermatogenic cells. These morphologic alterations were associated with a concomitant reduction of H, SDH, and LDH-X specific activities. In contrast, the specific activities of G3PDH and MDH were significantly elevated above control. The increase in these enzyme activities can be attributed to the relative enrichment of spermatogonial cells during the loss of spermatocytes and spermiogenic cells. Boron-induced male germinal aplasia was also associated with significantly elevated plasma FSH while plasma LH and testosterone levels were not significantly altered. Plasma testosterone levels were unaltered. Male fertility studies demonstrated that at the 500 ppm boron level, fertility was unaffected. However, at 1000 and 2000 ppm boron, male fertility was significantly reduced. Most effects were reversible within 5 weeks. However, the male group receiving 2000 ppm boron for 60 days remained sterile. There was no dose-related decrease in litter size or fetal death in utero. Therefore, the boron-induced infertility was apparently not due to a dominant lethal effect but rather to germinal aplasia. Boron appears toxic to spermatogenic cells at testicular concentrations of 6–8 ppm. ImagesFIGURE 6.FIGURE 9. PMID:446458

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

NASA Technical Reports Server (NTRS)

Tanaka, Hidehiko

1987-01-01

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Depth resolved investigations of boron implanted silicon

NASA Astrophysics Data System (ADS)

Sztucki, M.; Metzger, T. H.; Milita, S.; Berberich, F.; Schell, N.; Rouvière, 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 6×10 15 ions/cm -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 {1 1 1} 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.

Structural and electronic properties of boron-doped double-walled silicon carbide nanotubes

NASA Astrophysics Data System (ADS)

Behzad, Somayeh; Moradian, Rostam; Chegel, Raad

2010-12-01

The effects of boron doping on the structural and electronic properties of (6,0)@(14,0) double-walled silicon carbide nanotube (DWSiCNT) are investigated by using spin-polarized density functional theory. It is found that boron atom could be more easily doped in the inner tube. Our calculations indicate that a Si site is favorable for B under C-rich condition and a C site is favorable under Si-rich condition. Additionally, B-substitution at either single carbon or silicon atom site in DWSiCNT could induce spontaneous magnetization.

Dynamics of the formation and loss of boron atoms in a H2/B2H6 microwave plasma

NASA Astrophysics Data System (ADS)

Duluard, C. Y.; Aubert, X.; Sadeghi, N.; Gicquel, A.

2016-09-01

For further improvements in doped-diamond deposition technology, an understanding of the complex chemistry in H2/CH4/B2H6 plasmas is of general importance. In this context, a H2/B2H6 plasma ignited by microwave power in a near resonant cavity at high pressure (100-200 mbar) is studied to measure the B-atom density in the ground state. The discharge is ignited in the gas mixture (0-135 ppm B2H6 in H2) by a 2.45 GHz microwave generator, leading to the formation of a hemispheric plasma core, surrounded by a faint discharge halo filling the remaining reactor volume. Measurements with both laser induced fluorescence and resonant absoption with a boron hollow cathode lamp indicate that the B-atom density is higher in the halo than in the plasma core. When the absorption line-of-sight is positioned in the halo, the absorption is so strong that the upper detection limit is reached. To understand the mechanisms of creation and loss of boron atoms, time-resolved absorption measurements have been carried out in a pulsed plasma regime (10 Hz, duty cycle 50%). The study focuses on the influence of the total pressure, the partial pressure of B2H6, as well as the source power, on the growth and decay rates of boron atoms when the plasma is turned off.

Boron isotopic constraints on the source of Hawaiian shield lavas

NASA Astrophysics Data System (ADS)

Tanaka, Ryoji; Nakamura, Eizo

2005-07-01

Boron isotopic compositions of lavas from three representative Hawaiian shield volcanoes (Kilauea, Mauna Loa, and Koolau) were analyzed by thermal ionization mass spectrometry. The boron isotopic composition of each sample was analyzed twice, once with and once without acid leaching to evaluate the effect of posteruptive boron contamination. Our acid-leaching procedure dissolved glass, olivine, secondary zeolite, and adsorbed boron; this dissolved boron was completely removed from the residue, which was comprised of plagioclase, pyroxenes, and newly formed amorphous silica. We confirmed that an appropriate acid-leaching process can eliminate adsorbed and incorporated boron contamination from all submarine samples without modifying the original 11B/ 10B ratio. On the other hand, when the sample was weathered, i.e., the olivine had an iddingsite rim, 11B/ 10B of the acid-resistant minerals are also modified, thus it is impossible to get the preeruptive 11B/ 10B value from the weathered samples. Through this elimination and evaluation procedure of posteruptive contamination, preeruptive δ 11B values for the shield lavas are -4.5 to -5.4‰ for Koolau ( N = 8), -3.6 to -4.6‰ for Kilauea ( N = 11), and -3.0 to -3.8‰ for Mauna Loa ( N = 6). Historical Kilauea lavas show a systematic temporal trend for B content and Nb/B coupled with other radiogenic isotopic ratios and trace element ratios, at constant δ 11B, indicating little or no assimilation of crustal materials in these lavas. Uncorrelated B content and δ 11B in Koolau and Mauna Loa lavas may also indicate little or no effect of crustal assimilation in these lavas. The source of KEA-component (identical to the so-called Kea end member in Hawaiian lavas) of the Hawaiian source mantle, represented by Kilauea, should be derived from lower part of subducted oceanic crust or refractory peridotite in the recycled subducted slab. The systematic trend from Kilauea to Koolau—decreasing δ 11B coupled with decreasing ɛNd as well as increasing 87Sr/ 86Sr and 206Pb/ 204Pb—is consistent with involvement of subducted sediment components in the EMK(enriched Makapuu)-component, represented by Makapuu-stage of Koolau lavas.

Large Area Few Layers Hexagonal Boron Nitride Prepared by Quadrupole Field Aided Exfoliation.

PubMed

Hanlun, Lu; Rong, Min Zhi; Zhang, Ming Qiu

2018-01-16

A quadrupole electric field mediated exfoliation method is proposed to convert micron sized hexagonal boron nitride (hBN) powders into few layers hexagonal boron nitride nano-sheets (h-BNNS). Under the optimum conditions (400 Hz, 40 V, 32μg/mL, sodium deoxycholate, TAE medium), the hBN powders (thickness > 200 nm, horizontal scale ~ 10 μm) are successfully exfoliated into 0.5-4 nm (1-10 layers) thick h-BNNS with the same horizontal scale. Dynamic laser scattering (DLS) and atomic force microscope (AFM) statistics show that the yield is 47.6 % (for the portion with the thickness of 0.5-6 nm), and all of the vertical sizes are reduced to smaller than 18 nm (45 layers). © 2018 IOP Publishing Ltd.

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

PubMed

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

2007-01-01

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

Probing carbon impurities in hexagonal boron nitride epilayers

NASA Astrophysics Data System (ADS)

Uddin, M. R.; Li, J.; Lin, J. Y.; Jiang, H. X.

2017-05-01

Carbon doped hexagonal boron nitride epilayers have been grown by metal organic chemical vapor deposition. Photocurrent excitation spectroscopy has been utilized to probe the energy levels associated with carbon impurities in hexagonal boron nitride (h-BN). The observed transition peaks in photocurrent excitation spectra correspond well to the energy positions of the bandgap, substitutional donors (CB, carbon impurities occupying boron sites), and substitutional acceptors (CN, carbon impurities occupying nitrogen sites). From the observed transition peak positions, the derived energy level of CB donors in h-BN is ED ˜ 0.45 eV, which agrees well with the value deduced from the temperature dependent electrical resistivity. The present study further confirms that the room temperature bandgap of h-BN is about 6.42-6.45 eV, and the CN deep acceptors have an energy level of about 2.2-2.3 eV. The results also infer that carbon doping introduces both shallow donors (CB) and deep acceptors (CN) via self-compensation, and the energy level of carbon donors appears to be too deep to enable carbon as a viable candidate as an n-type dopant in h-BN epilayers.

Nanoporous Boron Nitride as Exceptionally Thermally Stable Adsorbent: Role in Efficient Separation of Light Hydrocarbons.

PubMed

Saha, Dipendu; Orkoulas, Gerassimos; Yohannan, Samuel; Ho, Hoi Chun; Cakmak, Ercan; Chen, Jihua; Ozcan, Soydan

2017-04-26

In this work, nanoporous boron nitride sample was synthesized with a Brunauer-Emmett-Teller (BET) surface area of 1360 m 2 /g and particle size 5-7 μm. The boron nitride was characterized with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electron microscopy (TEM and SEM). Thermogravimetric analysis (TGA) under nitrogen and air and subsequent analysis with XPS and XRD suggested that its structure is stable in air up to 800 °C and in nitrogen up to 1050 °C, which is higher than most of the common adsorbents reported so far. Nitrogen and hydrocarbon adsorption at 298 K and pressure up to 1 bar suggested that all hydrocarbon adsorption amounts were higher than that of nitrogen and the adsorbed amount of hydrocarbon increases with an increase in its molecular weight. The kinetics of adsorption data suggested that adsorption becomes slower with the increase in molecular weight of hydrocarbons. The equilibrium data suggested that that boron nitride is selective to paraffins in a paraffin-olefin mixture and hence may act as an "olefin generator". The ideal adsorbed solution theory (IAST)-based selectivity for CH 4 /N 2 , C 2 H 6 /CH 4 , and C 3 H 8 /C 3 H 6 was very high and probably higher than the majority of adsorbents reported in the literature. IAST-based calculations were also employed to simulate the binary mixture adsorption data for the gas pairs of CH 4 /N 2 , C 2 H 6 /CH 4 , C 2 H 6 /C 2 H 4 , and C 3 H 8 /C 3 H 6 . Finally, a simple mathematical model was employed to simulate the breakthrough behavior of the above-mentioned four gas pairs in a dynamic column experiment. The overall results suggest that nanoporous boron nitride can be used as a potential adsorbent for light hydrocarbon separation.

Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages.

PubMed

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.

Boron Induces Lymphocyte Proliferation and Modulates the Priming Effects of Lipopolysaccharide on Macrophages

PubMed Central

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. PMID:26934748

Longitudinal residual stresses in boron fibers

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1976-01-01

A method of measuring the longitudinal residual stress distribution in boron fibers is presented. The residual stresses in commercial CVD boron on tungsten fibers of 102, 142, and 203 microns (4, 5.6, and 8 mil) diameters were determined. Results for the three sizes show a compressive stress at the surface 800 to -1400 MN/sq m 120 to -200 ksi), changing monotonically to a region of tensile stress within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile 600 to 1000 MN/sq m(90 to 150 ksi) and then decreases to compressive near the tungsten boride core. The core itself is under a compressive stress of approximately -1300 MN/sq m (-190 ksi). The effects of surface removal on core residual stress and core-initiated fracture are discussed.

Theoretical investigation of calcium-decorated β12 boron sheet for hydrogen storage

NASA Astrophysics Data System (ADS)

Tang, Xiao; Gu, Yuantong; Kou, Liangzhi

2018-03-01

From first-principles calculations based on density functional theory, we find that the recently synthesized β12 boron sheet is a perfect candidate for calcium-decoration and hydrogen storage application. In contrast to graphene where defects are required to capture Ca, the naturally formed hexagonal hollow ring in β12 boron sheet provides the ideal site for Ca adsorption, and up to 6H2 molecules for each Ca atom can be captured with a desirable binding energy of ∼0.2 eV/H2. The gravimetric hydrogen density for Ca decorated boron sheet can reach up to 8.92 wt%. From the electronic analysis, it is found that both the orbital hybridizations and polarization mechanism play significant roles in H2 adsorption and storage.

Equilibrium p-T Phase Diagram of Boron: Experimental Study and Thermodynamic Analysis

PubMed Central

Solozhenko, Vladimir L.; Kurakevych, Oleksandr O.

2013-01-01

Solid-state phase transformations and melting of high-purity crystalline boron have been in situ and ex situ studied at pressures to 20 GPa in the 1500–2500 K temperature range where diffusion processes become fast and lead to formation of thermodynamically stable phases. The equilibrium phase diagram of boron has been constructed based on thermodynamic analysis of experimental and literature data. The high-temperature part of the diagram contains p-T domains of thermodynamic stability of rhombohedral β-B106, orthorhombic γ-B28, pseudo-cubic (tetragonal) t'-B52, and liquid boron (L). The positions of two triple points have been experimentally estimated, i.e. β–t'–L at ~ 8.0 GPa and ~ 2490 K; and β–γ–t' at ~ 9.6 GPa and ~ 2230 K. Finally, the proposed phase diagram explains all thermodynamic aspects of boron allotropy and significantly improves our understanding of the fifth element. PMID:23912523

Alloy Design of Martensitic 9Cr-Boron Steel for A-USC Boiler at 650 °C — Beyond Grades 91, 92 and 122

NASA Astrophysics Data System (ADS)

Abe, Fujio; Tabuchi, M.; Tsukamoto, S.

Boundary hardening is shown to be the most important strengthening mechanism in creep of tempered martensitic 9% Cr steel base metal and welded joints at 650 °C. The enrichment of soluble boron near prior austenite grain boundaries (PAGBs) by the GB segregation is essential for the reduction of coarsening rate of M23C6 carbides near PAGBs, enhancing the boundary and sub-boundary hardening near PAGBs, and also for the change in α/γ transformation behavior in heat-affected-zone (HAZ) of welded joints during heating of welding, producing the same microstructure in HAZ as in the base metal. Excess addition of nitrogen to the 9Cr-boron steel promotes the formation of boron nitrides during normalizing heat treatment, which consumes most of soluble boron and degrades the creep strength. A NIMS 9Cr steel (MARBN; Martensitic 9Cr steel strengthened by boron and MX nitrides) with 120-150 ppm boron and 60-90 ppm nitrogen, where no boron nitride forms during normalizing heat treatment, exhibits not only much higher creep strength of base metal than Grades 91, 92 and 122 but also substantially no degradation in creep strength due to Type IV fracture in HAZ of welded joints at 650°C. The protective Cr2O3-rich scale forms on the surface of 9Cr steel by pre-oxidation treatment in Ar gas, which significantly improves the oxidation resistance in steam at 650°C.

Methods to assess reproductive effects of environmental chemicals: studies of cadmium and boron administered orally.

PubMed Central

Dixon, R L; Lee, I P; Sherins, R J

1976-01-01

Results of a U.S.S.R.--U.S. cooperative laboratory effort to improve and validate experimental techniques used to assess subtle reproductive effects in male laboratory animals are reported. The present studies attempted to evaluate the reproductive toxicity of cadmium as cadmium chloride and boron as borax (Na2B4O7) and to investigate the mechanism of toxicity in the rat following acute and subchronic oral exposure. In vitro cell separation techniques, in vivo serial mating tests, and plasma assays for hormones were utilized. Effects on the seminal vesicle and prostate were evaluated with chemical and enzyme assays. Clinical chemistry was monitored routinely. Acute oral doses, expressed as boron were 45, 150, and 450 mg/kg while doses for cadmium equivalent were 6.25, 12.5, and 25 mg/kg. Rats were also allowed free access to drinking water containing either boron (0.3, 1.0, and 6.0 mg/l.) or cadmium (0.001, and 0.l mg/l.) for 90 days. Randomly selected animals were studied following 30, 60, and 90 days of treatment. These initial studies, utilizing a variety of methods to assess the reproductive toxicity of environmental substances in male animals, suggest that cadmium and boron at the concentrations and dose regimens tested are without significant reproductive toxicity. PMID:1269508

Interaction of boron cluster ions with water: Single collision dynamics and sequential etching

NASA Astrophysics Data System (ADS)

Hintz, Paul A.; Ruatta, Stephen A.; Anderson, Scott L.

1990-01-01

Reactions of mass-selected, cooled, boron cluster ions (B+n, n=1-14) with water have been studied for collision energies from 0.1 to 6.0 eV. Most work was done with D2O, however isotope effects were examined for selected reactant cluster ions. For all size clusters there are exoergic product channels, which in most cases have no activation barriers. Cross sections are generally large, however there are fluctuations with cluster size in total reactivity, collision energy dependences, and in product distributions. For small cluster ions, there is a multitude of product channels. For clusters larger than B+6, the product distributions are dominated by a single channel: Bn-1D++DBO. Under multiple collision conditions, the primary products undergo a remarkable sequence of secondary ``etching'' reactions. As these occur, boron atoms are continuously replaced by hydrogen, and the intermediate products retain the composition: Bn-mH+m. This highly efficient chemistry appears to continue unchanged as the composition changes from pure boron to mostly hydrogen. Comparison of these results is made with boron cluster ion reactions with O2 and D2, as well as reactions with water of aluminum and silicon cluster ions. Some discussion is given of the thermochemistry for these reactions, and a possible problem with the thermochemical data in the BOD/DBO system is discussed.

Boron nitride microfibers grown by plasma-assisted laser chemical vapor deposition without a metal catalyst

NASA Astrophysics Data System (ADS)

Komatsu, Shojiro; Kazami, Daisuke; Tanaka, Hironori; Shimizu, Yoshiki; Moriyoshi, Yusuke; Shiratani, Masaharu; Okada, Katsuyuki

2006-04-01

Boron nitride fibers were found to grow on polycrystalline nickel and Si (100) substrates by plasma-assisted laser chemical vapor deposition from B2H6+NH3 using an excimer laser at 193nm. Their diameter was typically a few hundreds of nanometers, while the length was a few tens of micrometers. They were stoichiometric or boron-rich BN in chemical composition. When the substrate was rotated during deposition, spiral fibers were found to grow. We conclude that they grew with the help of laser light by other than the vapor - liquid - solid mechanism.

Synthesis of n-type semiconductor diamond single crystal under high pressure and high temperature

NASA Astrophysics Data System (ADS)

Li, Yong; Li, Shangsheng; Song, Mousheng; She, Yanchao; Wang, Qiang; Guan, Xuemao

2017-12-01

In this paper, diamond single crystal co-doped with sulfur and boron was successfully synthesized at the fixed pressure of 6.0 GPa and temperature range of 1535 K. Sulfur was detected in the co-doped diamond by Fourier Transform Infrared Spectroscopy (FTIR) and the corresponding characteristic peak located at 848 cm-1. Interestingly, Hall effect measurements indicated that the diamond co-doped with sulfur and boron exhibited n-type semiconductor behaviour. Furthermore, the Hall mobility and carrier concentration of the co-doped diamond higher than those of the boron-doping diamond.

Surface Chemistry, Microstructure, and Tribological Properties of Cubic Boron Nitride Films

NASA Technical Reports Server (NTRS)

Watanabe, Shuichi; Wheeler, Donald R.; Abel, Phillip B.; Street, Kenneth W.; Miyoshi, Kazuhisa; Murakawa, Masao; Miyake, Shojiro

1998-01-01

This report deals with the surface chemistry, microstructure, bonding state, morphology, and friction and wear properties of cubic boron nitride (c-BN) films that were synthesized by magnetically enhanced plasma ion plating. Several analytical techniques - x-ray photoelectron spectroscopy, transmission electron microscopy and electron diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, and surface profilometry - were used to characterize the films. Sliding friction experiments using a ball-on-disk configuration were conducted for the c-BN films in sliding contact with 440C stainless-steel balls at room temperature in ultrahigh vacuum (pressure, 10(exp -6), in ambient air, and under water lubrication. Results indicate that the boron-to-nitrogen ratio on the surface of the as-deposited c-BN film is greater than 1 and that not all the boron is present as boron nitride but a small percentage is present as an oxide. Both in air and under water lubrication, the c-BN film in sliding contact with steel showed a low wear rate, whereas a high wear rate was observed in vacuum. In air and under water lubrication, c-BN exhibited wear resistance superior to that of amorphous boron nitride, titanium nitride, and titanium carbide.

Development of real-time thermal neutron monitor using boron-loaded plastic scintillator with optical fiber for boron neutron capture therapy.

PubMed

Ishikawa, M; Ono, K; Sakurai, Y; Unesaki, H; Uritani, A; Bengua, G; Kobayashi, T; Tanaka, K; Kosako, T

2004-11-01

A new thermal neutron monitor for boron neutron capture therapy was developed in this study. We called this monitor equipped boron-loaded plastic scintillator that uses optical fiber for signal transmission as an [scintillator with optical fiber] SOF detector. A water phantom experiment was performed to verify how the SOF detector compared with conventional method of measuring thermal neutron fluence. Measurements with a single SOF detector yielded indistinguishable signals for thermal neutrons and gamma rays. To account for the gamma ray contribution in the signal recorded by the SOF detector, a paired SOF detector system was employed. This was composed of an SOF detector with boron-loaded scintillator and an SOF detector with a boron-free scintillator. The difference between the recorded counts of these paired SOF detectors was used as the measure of the gamma ray contribution in the measured neutron fluence. The paired SOF detectors were ascertained to be effective in measuring thermal neutron flux in the range above 10(6)(n/cm(2)/s). Clinical trials using paired SOF to measure thermal neutron flux during therapy confirmed that paired SOF detectors were effective as a real-time thermal neutron flux monitor.

Effect of Carbon Doping on the Electronic Structure and Elastic Properties of Boron Suboxide

DTIC Science & Technology

2015-06-01

harden or soften B6O. The hardening or softening depends on the location and the type of a dopant . When the doping creates a B4C-like local...Lett. 2005;86:041911. 9. Nifise E. Study of sintering and structure property relationships in boron suboxide – alkaline earth metal oxide, cobalt

Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams.

PubMed

Poppinga, D; Halbur, J; Lemmer, S; Delfs, B; Harder, D; Looe, H K; Poppe, B

2017-09-05

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm -3 ) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Test study of boron nitride as a new detector material for dosimetry in high-energy photon beams

NASA Astrophysics Data System (ADS)

Poppinga, D.; Halbur, J.; Lemmer, S.; Delfs, B.; Harder, D.; Looe, H. K.; Poppe, B.

2017-09-01

The aim of this test study is to check whether boron nitride (BN) might be applied as a detector material in high-energy photon-beam dosimetry. Boron nitride exists in various crystalline forms. Hexagonal boron nitride (h-BN) possesses high mobility of the electrons and holes as well as a high volume resistivity, so that ionizing radiation in the clinical range of the dose rate can be expected to produce a measurable electrical current at low background current. Due to the low atomic numbers of its constituents, its density (2.0 g cm-3) similar to silicon and its commercial availability, h-BN appears as possibly suitable for the dosimetry of ionizing radiation. Five h-BN plates were contacted to triaxial cables, and the detector current was measured in a solid-state ionization chamber circuit at an applied voltage of 50 V. Basic dosimetric properties such as formation by pre-irradiation, sensitivity, reproducibility, linearity and temporal resolution were measured with 6 MV photon irradiation. Depth dose curves at quadratic field sizes of 10 cm and 40 cm were measured and compared to ionization chamber measurements. After a pre-irradiation with 6 Gy, the devices show a stable current signal at a given dose rate. The current-voltage characteristic up to 400 V shows an increase in the collection efficiency with the voltage. The time-resolved detector current behavior during beam interrupts is comparable to diamond material, and the background current is negligible. The measured percentage depth dose curves at 10 cm  ×  10 cm field size agreed with the results of ionization chamber measurements within  ±2%. This is a first study of boron nitride as a detector material for high-energy photon radiation. By current measurements on solid ionization chambers made from boron nitride chips we could demonstrate that boron nitride is in principle suitable as a detector material for high-energy photon-beam dosimetry.

Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

NASA Astrophysics Data System (ADS)

Keddam, Mourad; Taktak, Sukru

2017-03-01

The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973-1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB2 top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB2 and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB2 and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB2 and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol-1, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

Energy efficient synthesis of boranes

DOEpatents

Thorn, David L [Los Alamos, NM; Tumas, William [Los Alamos, NM; Schwarz, Daniel E [Los Alamos, NM; Burrell, Anthony K [Los Alamos, NM

2012-01-24

The reaction of halo-boron compounds (B--X compounds, compounds having one or more boron-halogen bonds) with silanes provides boranes (B--H compounds, compounds having one or more B--H bonds) and halosilanes. Inorganic hydrides, such as surface-bound silane hydrides (Si--H) react with B--X compounds to form B--H compounds and surface-bound halosilanes. The surface bound halosilanes are converted back to surface-bound silanes electrochemically. Halo-boron compounds react with stannanes (tin compounds having a Sn--H bond) to form boranes and halostannanes (tin compounds having a Sn--X bond). The halostannanes are converted back to stannanes electrochemically or by the thermolysis of Sn-formate compounds. When the halo-boron compound is BCl.sub.3, the B--H compound is B.sub.2H.sub.6, and where the reducing potential is provided electrochemically or by the thermolysis of formate.

Energy efficient synthesis of boranes

DOEpatents

Thorn, David L.; Tumas, William; Schwarz, Daniel E.; Burrell, Anthony K.

2010-11-23

The reaction of halo-boron compounds (B--X compounds, compounds having one or more boron-halogen bonds) with silanes provides boranes (B--H compounds, compounds having one or more B--H bonds) and halosilanes. Inorganic hydrides, such as surface-bound silane hydrides (Si--H) react with B--X compounds to form B--H compounds and surface-bound halosilanes. The surface bound halosilanes are converted back to surface-bound silanes electrochemically. Halo-boron compounds react with stannanes (tin compounds having a Sn--H bond) to form boranes and halostannanes (tin compounds having a Sn--X bond). The halostannanes are converted back to stannanes electrochemically or by the thermolysis of Sn-formate compounds. When the halo-boron compound is BCl.sub.3, the B--H compound is B.sub.2H.sub.6, and where the reducing potential is provided electrochemically or by the thermolysis of formate.

Structural models of increasing complexity for icosahedral boron carbide with compositions throughout the single-phase region from first principles

NASA Astrophysics Data System (ADS)

Ektarawong, A.; Simak, S. I.; Alling, B.

2018-05-01

We perform first-principles calculations to investigate the phase stability of boron carbide, concentrating on the recently proposed alternative structural models composed not only of the regularly studied B11Cp (CBC) and B12(CBC), but also of B12(CBCB) and B12( B4 ). We find that a combination of the four structural motifs can result in low-energy electron precise configurations of boron carbide. Among several considered configurations within the composition range of B10.5C and B4C , we identify in addition to the regularly studied B11Cp (CBC) at the composition of B4C two low-energy configurations, resulting in a new view of the B-C convex hull. Those are [B12 (CBC)]0.67[B12(B4)] 0.33 and [B12 (CBC)]0.67[ B12 (CBCB)]0.33, corresponding to compositions of B10.5C and B6.67C , respectively. As a consequence, B12(CBC) at the composition of B6.5C , previously suggested in the literature as a stable configuration of boron carbide, is no longer part of the B -C convex hull. By inspecting the electronic density of states as well as the elastic moduli, we find that the alternative models of boron carbide can provide a reasonably good description for electronic and elastic properties of the material in comparison with the experiments, highlighting the importance of considering B12(CBCB) and B12( B4 ), together with the previously proposed B11Cp (CBC) and B12(CBC), as the crucial ingredients for modeling boron carbide with compositions throughout the single-phase region.

Structure, Mechanics and Synthesis of Nanoscale Carbon and Boron Nitride

NASA Astrophysics Data System (ADS)

Rinaldo, Steven G.

This thesis is divided into two parts. In Part I, we examine the properties of thin sheets of carbon and boron nitride. We begin with an introduction to the theory of elastic sheets, where the stretching and bending modes are considered in detail. The coupling between stretching and bending modes is thought to play a crucial role in the thermodynamic stability of atomically-thin 2D sheets such as graphene. In Chapter 2, we begin by looking at the fabrication of suspended, atomically thin sheets of graphene. We then study their mechanical resonances which are read via an optical transduction technique. The frequency of the resonators was found to depend on their temperature, as was their quality factor. We conclude by offering some interpretations of the data in terms of the stretching and bending modes of graphene. In Chapter 3, we look briefly at the fabrication of thin sheets of carbon and boron nitride nanotubes. We examine the structure of the sheets using transmission and scanning electron microscopy (TEM and SEM, respectively). We then show a technique by which one can make sheets suspended over a trench with adjustable supports. Finally, DC measurements of the resistivity of the sheets in the temperature range 600 -- 1400 C are presented. In Chapter 4, we study the folding of few-layer graphene oxide, graphene and boron nitride into 3D aerogel monoliths. The properties of graphene oxide are first considered, after which the structure of graphene and boron nitride aerogels is examined using TEM and SEM. Some models for their structure are proposed. In Part II, we look at synthesis techniques for boron nitride (BN). In Chapter 5, we study the conversion of carbon structures of boron nitride via the application of carbothermal reduction of boron oxide followed by nitridation. We apply the conversion to a wide variety of morphologies, including aerogels, carbon fibers and nanotubes, and highly oriented pyrolytic graphite. In the latter chapters, we look at the formation of boron nitride nanotubes (BNNTs). In Chapter 6, we look at various methods of producing BNNTs from boron droplets, and introduce a new method involving injection of boron powder into an induction furnace. In Chapter 7 we consider another useful process, where ammonia is reacted with boron vapor generated in situ, either through the reaction of boron with metal oxides or through the decomposition of metal borides.

Thermodynamics and Kinetics of Boron Removal from Metallurgical Grade Silicon by Addition of High Basic Potassium Carbonate to Calcium Silicate Slag

NASA Astrophysics Data System (ADS)

Wu, Jijun; Wang, Fanmao; Ma, Wenhui; Lei, Yun; Yang, Bin

2016-06-01

In this study, we investigated the thermodynamics and kinetics of boron removal from metallurgical grade silicon (MG-Si) using a calcium silicate slag containing a high basic potassium carbonate. The distribution of boron between slag and silicon was theoretically derived and the distribution coefficients ( L B) of boron with different compositions of CaO, SiO2, and K2CO3 in slag reagents were determined. The maximal value of L B reached 2.08 with a high basicity slag of 40 pctCaO-40 pctSiO2-20 pctK2CO3 (Λ = 0.73). The boron removal rates from MG-Si using CaO-SiO2 and CaO-SiO2-K2CO3 slags at 1823 K (1550 °C) were investigated in an electromagnetic induction furnace. The results showed that the boron concentration in MG-Si can be reduced from 22 to 1.8 ppmw at 1823 K (1550 °C) with 20 pct K2CO3 addition to calcium silicate slag, where the removal efficiency of boron reached 91.8 pct. The mass transfer coefficient ( β S) of boron in binary 50 pctCaO-50 pctSiO2 slag was 3.16 × 10-6 m s-1 at 1823 K (1550 °C) and was 2.43 × 10-5 m s-1 in ternary 40 pctCaO-40 pctSiO2-20 pctK2CO3 slag.

A new selective fluorene-based fluorescent internal charge transfer (ICT) sensor for sugar alcohols in aqueous solution.

PubMed

Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona

2016-03-01

Sugar alcohols, such as sorbitol, are commonly used as a replacement for sucrose in the food industry, applied as starting material for vitamin C synthesis, and involved as one of the causative factors in diabetic complications. Therefore, their detection and quantification in aqueous solution are necessary. The reversible covalent interactions between boronic acids and diols are the basis of efficient methods for the detection of saccharides. Herein, we report a new internal charge transfer (ICT) fluorene-based fluorescent boronic acid sensor (1) 2-[(9,9-dimethyl-9H-fluoren-2-yl-amino)methyl] phenyl boronic acid that shows significant fluorescence changes upon addition of saccharides. The boronic acid has high affinity (K a = 1107.9 M(-1)) and selectivity for sorbitol at pH = 8.31. It showed a linear response toward sorbitol in the concentration range from 1.0 × 10(-5) to 6.0 × 10(-4) mol L(-1) with the detection limit of 7.04 × 10(-6) mol L(-1). Sensor 1 was used to detect sorbitol in real samples with good recovery.

Photoinduced DNA Interstrand Cross-Link Formation by Naphthalene Boronates via a Carbocation.

PubMed

Wang, Yibin; Lin, Zechao; Fan, Heli; Peng, Xiaohua

2016-07-18

Most photoinduced DNA cross-link formation by a bifunctional aryl derivative is through a bisquinone methide. DNA cross-linking via a bisarylcarbocation remains a less explored area. We designed and synthesized a series of naphthalene boronates that produce DNA interstrand cross-links via a carbocation upon UV irradiation. A free radical was generated from the naphthalene boronates with 350 nm irradiation and further converted to a carbocation by electron transfer. The activation mechanism was determined using the orthogonal traps, 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) and methoxyamine that react with either the free radical or the carbocation but not both. This represents a novel example of photoinduced DNA cross-link formation via carbocations generated from a bisaryl derivative. This work provides information useful for the design of novel photoactivated DNA cross-linking agents. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum chemical investigation of levofloxacin-boron complexes: A computational approach

NASA Astrophysics Data System (ADS)

Sayin, Koray; Karakaş, Duran

2018-04-01

Quantum chemical calculations are performed over some boron complexes with levofloxacin. Boron complex with fluorine atoms are optimized at three different methods (HF, B3LYP and M062X) with 6-31 + G(d) basis set. The best level is determined as M062X/6-31 + G(d) by comparison of experimental and calculated results of complex (1). The other complexes are optimized by using the best level. Structural properties, IR and NMR spectrum are examined in detail. Biological activities of mentioned complexes are investigated by some quantum chemical descriptors and molecular docking analyses. As a result, biological activities of complex (2) and (4) are close to each other and higher than those of other complexes. Additionally, NLO properties of mentioned complexes are investigated by some quantum chemical parameters. It is found that complex (3) is the best candidate for NLO applications.

Increased Thymic Cell Turnover under Boron Stress May Bypass TLR3/4 Pathway in African Ostrich

PubMed Central

Huang, Hai-bo; Xiao, Ke; Lu, Shun; Yang, Ke-li; Ansari, Abdur Rahman; Khaliq, Haseeb; Song, Hui; Zhong, Juming; Liu, Hua-zhen; Peng, Ke-mei

2015-01-01

Previous studies revealed that thymus is a targeted immune organ in malnutrition, and high-boron stress is harmful for immune organs. African ostrich is the living fossil of ancient birds and the food animals in modern life. There is no report about the effect of boron intake on thymus of ostrich. The purpose of present study was to evaluate the effect of excessive boron stress on ostrich thymus and the potential role of TLR3/4 signals in this process. Histological analysis demonstrated that long-term boron stress (640 mg/L for 90 days) did not disrupt ostrich thymic structure during postnatal development. However, the numbers of apoptotic cells showed an increased tendency, and the expression of autophagy and proliferation markers increased significantly in ostrich thymus after boron treatment. Next, we examined the expression of TLR3 and TLR4 with their downstream molecular in thymus under boron stress. Since ostrich genome was not available when we started the research, we first cloned ostrich TLR3 TLR4 cDNA from thymus. Ostrich TLR4 was close to white-throated Tinamou. Whole avian TLR4 codons were under purify selection during evolution, whereas 80 codons were under positive selection. TLR3 and TLR4 were expressed in ostrich thymus and bursa of fabricius as was revealed by quantitative real-time PCR (qRT-PCR). TLR4 expression increased with age but significantly decreased after boron treatment, whereas TLR3 expression showed the similar tendency. Their downstream molecular factors (IRF1, JNK, ERK, p38, IL-6 and IFN) did not change significantly in thymus, except that p100 was significantly increased under boron stress when analyzed by qRT-PCR or western blot. Taken together, these results suggest that ostrich thymus developed resistance against long-term excessive boron stress, possibly by accelerating intrathymic cell death and proliferation, which may bypass the TLR3/4 pathway. In addition, attenuated TLRs activity may explain the reduced inflammatory response to pathogens under boron stress. PMID:26053067

Increased Thymic Cell Turnover under Boron Stress May Bypass TLR3/4 Pathway in African Ostrich.

PubMed

Huang, Hai-bo; Xiao, Ke; Lu, Shun; Yang, Ke-li; Ansari, Abdur Rahman; Khaliq, Haseeb; Song, Hui; Zhong, Juming; Liu, Hua-zhen; Peng, Ke-mei

2015-01-01

Previous studies revealed that thymus is a targeted immune organ in malnutrition, and high-boron stress is harmful for immune organs. African ostrich is the living fossil of ancient birds and the food animals in modern life. There is no report about the effect of boron intake on thymus of ostrich. The purpose of present study was to evaluate the effect of excessive boron stress on ostrich thymus and the potential role of TLR3/4 signals in this process. Histological analysis demonstrated that long-term boron stress (640 mg/L for 90 days) did not disrupt ostrich thymic structure during postnatal development. However, the numbers of apoptotic cells showed an increased tendency, and the expression of autophagy and proliferation markers increased significantly in ostrich thymus after boron treatment. Next, we examined the expression of TLR3 and TLR4 with their downstream molecular in thymus under boron stress. Since ostrich genome was not available when we started the research, we first cloned ostrich TLR3 TLR4 cDNA from thymus. Ostrich TLR4 was close to white-throated Tinamou. Whole avian TLR4 codons were under purify selection during evolution, whereas 80 codons were under positive selection. TLR3 and TLR4 were expressed in ostrich thymus and bursa of fabricius as was revealed by quantitative real-time PCR (qRT-PCR). TLR4 expression increased with age but significantly decreased after boron treatment, whereas TLR3 expression showed the similar tendency. Their downstream molecular factors (IRF1, JNK, ERK, p38, IL-6 and IFN) did not change significantly in thymus, except that p100 was significantly increased under boron stress when analyzed by qRT-PCR or western blot. Taken together, these results suggest that ostrich thymus developed resistance against long-term excessive boron stress, possibly by accelerating intrathymic cell death and proliferation, which may bypass the TLR3/4 pathway. In addition, attenuated TLRs activity may explain the reduced inflammatory response to pathogens under boron stress.

Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Alver, Ü.; Tanrıverdi, A.

2016-08-01

In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

Intra-Shell boron isotope ratios in benthic foraminifera: Implications for paleo-pH reconstructions

NASA Astrophysics Data System (ADS)

Rollion-Bard, C.; Erez, J.

2009-12-01

The boron isotope composition of marine carbonates is considered to be a seawater pH proxy. Nevertheless, the use of δ11B has some limitations: 1) the knowledge of fractionation factor (α4-3) between the two boron dissolved species (boric acid and borate ion), 2) the δ11B of seawater may have varied with time and 3) the amplitude of the "vital effects" of this proxy. Using secondary ion mass spectrometry (SIMS), we looked at the internal variability in the boron isotope ratio of the shallow water, symbionts bearing foraminiferan Amphistegina lobifera. Specimens were cultured at constant temperature (24±0.1 °C) in seawater with pH ranging between 7.90 and 8.45. We performed 6 to 8 measurements of δ11B in each foraminifera. Intra-shell boron isotopes show large variability with an upper threshold value of pH ~ 9. The ranges of the skeletal calculated pH values in different cultured foraminifera, show strong correlation with the culture pH values and may thus serve as proxy for pH in the past ocean.

Fracture mechanics correlation of boron/aluminum coupons containing stress risers

NASA Technical Reports Server (NTRS)

Adsit, N. R.; Waszczak, J. P.

1975-01-01

The mechanical behavior of boron/aluminum near stress risers has been studied and reported. This effort was directed toward defining the tensile behavior of both unidirectional and (0/ plus or minus 45) boron/aluminum using linear elastic fracture mechanics (LEFM). The material used was 5.6-mil boron in 6061 aluminum, consolidated using conventional diffusion bonding techniques. Mechanical properties are reported for both unidirectional and (0/ plus or minus 45) boron/aluminum, which serve as control data for the fracture mechanics predictions. Three different flawed specimen types were studied. In each case the series of specimens remained geometrically similar to eliminate variations in finite size correction factors. The fracture data from these tests were reduced using two techniques. They both used conventional LEFM methods, but the existence of a characteristic flaw was assumed in one case and not the other. Both the data and the physical behavior of the specimens support the characteristic flaw hypothesis. Cracks were observed growing slowly in the (0/ plus or minus 45) laminates, until a critical crack length was reached at which time catastrophic failure occurred.

TEM Studies of Boron-Modified 17Cr-7Ni Precipitation-Hardenable Stainless Steel via Rapid Solidification Route

NASA Astrophysics Data System (ADS)

Gupta, Ankur; Bhargava, A. K.; Tewari, R.; Tiwari, A. N.

2013-09-01

Commercial grade 17Cr-7Ni precipitation-hardenable stainless steel has been modified by adding boron in the range 0.45 to 1.8 wt pct and using the chill block melt-spinning technique of rapid solidification (RS). Application of RS has been found to increase the solid solubility of boron and hardness of 17Cr-7Ni precipitation-hardenable stainless steel. The hardness of the boron-modified rapidly solidified alloys has been found to increase up to ~280 pct after isochronal aging to peak hardness. A TEM study has been carried out to understand the aging behavior. The presence of M23(B,C)6 and M2(B,C) borocarbides and epsilon-carbide in the matrix of austenite and ferrite with a change in heat treatment temperature has been observed. A new equation for Creq is also developed which includes the boron factor on ferrite phase stability. The study also emphasizes that aluminum only takes part in ferrite phase stabilization and remains in the solution.

In vitro induction of matrix metalloproteinase-2 and matrix metalloproteinase-9 expression in keratinocytes by boron and manganese.

PubMed

Chebassier, Nathalie; El Houssein, Ouijja; Viegas, Isabelle; Dréno, Brigitte

2004-08-01

Matrix metalloproteinase (MMP)-2 and MMP-9 are involved in keratinocyte migration and granulation tissue remodeling during wound healing. Thermal water cures are sometimes proposed as complementary treatment for accelerating healing of wounds resulting from burns and/or surgery, but their mechanisms of action remain unknown. Some thermal waters are rich in trace elements such as boron and manganese. Interestingly, clinical studies have shown the beneficial effects of trace elements such as boron and manganese for human wound healing. To try to specify the role of trace elements in cutaneous healing, the present study investigated the effects of these trace elements on the production of MMP-2 and MMP-9 by normal human keratinocytes cultured in vitro. Immunohistochemistry and Western blot showed that intracellular MMP-9 expression in keratinocytes was induced when incubated for 6 h with boron at 10 micro g/ml or manganese at 0.2 micro g/ml. Moreover, gelatin zymography on keratinocyte supernatants showed an increase of gelatinase secretion after 24 h of incubation of keratinocytes with boron or manganese, regardless of concentration. Gelatinase secretion was not associated with keratinocyte proliferation induced by trace elements. Thus, our results suggest that boron and manganese could play a role in the clinical efficiency of thermal water on wound healing.

Design of the magnetic homonuclear bonds boron nitride nanosheets using DFT methods.

PubMed

Anota, E Chigo; Hernández, A Bautista; Morales, A Escobedo; Castro, M

2017-06-01

Design and characterization of the structural, electronic, and magnetic properties of armchair boron-nitride, BN (B 27 N 27 H 18 ), nanosheets were performed by means of density functional theory all-electron calculations. The HSEh1PBE-GGA method together with 6-31G(d) basis sets were used. Non-stoichiometric B 30 N 24 H 18 and B 24 N 30 H 18 compositions: rich in boron or nitrogen atoms, forming homonuclear B or N bonds, respectively, were chosen. The obtained results reveal that these BN nanosheets reach structural stability in the anionic form, where semiconductor and magnetic behaviors are promoted. Effectively, the HOMO-LUMO gap is of 2.03 and 2.39eV, respectively and the magnetic moments are of 1.0 magneton bohrs, coming from the boron atoms in both systems. The rich in boron nanosheets present high-polarity, either in the gas phase or embedded in aqueous mediums like water, as well as low chemical reactivity, signifying potential applicability in the transportation of pharmaceutical species in biological mediums. These systems are also promising for the design of electronic devices, because they possess low-work functions, mainly arising from the homonuclear boron or nitrogen bond formation. Copyright © 2017 Elsevier Inc. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crabtree, D.J.

Three types of boron/epoxy prepreg tape were prestressed to fracture weak sites along the fiber by winding over 0.3- to 0.6-inch diameter rollers prior to lamination. The prestressed prepreg was then laminated, and design allowable testing was conducted to determine if mechanical strength properties are increased and data scatter is reduced by prestressing. The types of prepreg studied were standard 'Rigidite' 5505/4 prepreg, carbon substrate boron fiber prepreg, and a prepreg made from 'defect' tungsten substrate boron that was manufactured in a high-speed, low-cost, production process. The strength of angleply composites of both 'Rigidite' 5505/4 and carbon substrate boron compositesmore » were unaffected by prestressing. A study was made to determine if prepreg costs could be reduced by manufacturing low-cost 'defect' boron fiber and prestressing it to improve its properties. The results of this study were inconclusive. The test results show prestressing marginally improved some composite properties while others were reduced. On 'Rigidite' 5505/4 unidirectional composites, fatigue strength was significantly improved by prestressing, while longitudinal tensile strength was reduced at room temperature and 350 F. On unidirectional carbon substrate boron composites, the longitudinal tensile strength at room temperature and 350F was increased with attendant variability, while fatigue strength at high stress levels was reduced but not affected at low stress levels.« less

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

PubMed

Rao, Bin; Kinjo, Rei

2018-05-02

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

28-Homobrassinolide mitigates boron induced toxicity through enhanced antioxidant system in Vigna radiata plants.

PubMed

Yusuf, Mohammad; Fariduddin, Qazi; Ahmad, Aqil

2011-11-01

The objective of this study was to establish relationship between boron induced oxidative stress and antioxidant system in Vigna radiata plants and also to investigate whether brassinosteroids will enhance the level of antioxidant system that could confer tolerance to the plants from the boron induced oxidative stress. The mung bean (V. radiata cv. T-44) plants were administered with 0.50, 1.0 and 2.0 mM boron at 6 d stage for 7 d along with nutrient solution. At 13 d stage, the seedlings were sprayed with deionized water (control) or 10(-8) M of 28-homobrassinolide and plants were harvested at 21 d stage to assess growth, leaf gas-exchange traits and biochemical parameters. The boron treatments diminished growth, water relations and photosynthetic attributes along with nitrate reductase and carbonic anhydrase activity in the concentration dependent manner whereas, it enhanced lipid peroxidation, electrolyte leakage, accumulation of H(2)O(2) as well as proline, and various antioxidant enzymes in the leaves of mung bean which were more pronounced at higher concentrations of boron. However, the follow-up application of 28-homobrassinolide to the boron stressed plants improved growth, water relations and photosynthesis and further enhanced the various antioxidant enzymes viz. catalase, peroxidase and superoxide dismutase and content of proline. The elevated level of antioxidant enzymes as well as proline could have conferred tolerance to the B-stressed plants resulting in improved growth, water relations and photosynthetic attributes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization of the distribution of the sintering activator boron in powder metallurgical steels with SIMS.

PubMed

Krecar, Dragan; Vassileva, Vassilka; Danninger, Herbert; Hutter, Herbert

2004-06-01

Powder metallurgy is a well-established method for manufacturing ferrous precision parts. A very important step is sintering, which can be strongly enhanced by the formation of a liquid phase during the sintering process. Boron activates this process by forming such a liquid phase at about 1200 degrees C. In this work, the sintering of Fe-B was performed under the protective atmospheres of hydrogen, argon or nitrogen. Using different grain sizes of the added ferroboron leads to different formations of pores and to the formation of secondary pores. The effect of boron was investigated by means of Secondary Ion Mass Spectrometry (SIMS) supported by Scanning Electron Microscopy (SEM) and Light Microscopy (LM). To verify the influence of the process parameters on the mechanical properties, the microstructure (pore shape) was examined and impact energy measurements were performed. The concentrations of B in different samples were varied from 0.03-0.6 weight percent (wt%). Higher boron concentrations are detectable by EPMA, whereas the distributions of boron in the samples with interesting overall concentration in the low wt% range are only detectable by means of SIMS. This work shows that the distribution of boron strongly depends on its concentration and the sintering atmosphere used. At low concentration (up to 0.1 wt%) there are boride precipitations; at higher concentration there is a eutectic iron-boron grain boundary network. There is a decrease of the impact energy observed that correlates with the amount of eutectic phase.

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

NASA Astrophysics Data System (ADS)

Vengosh, Avner; Kolodny, Yehoshua; Starinsky, Abraham; Chivas, Allan R.; McCulloch, Malcolm T.

1991-10-01

The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The boron content of the biogenic skeletons is independent of mineralogical composition and is probably related to biological (vital) effects. The δ11B values of the carbonates range from 14.2 to 32.2%. (relative to NBS SRM 951) and overlap with the δ11B values of modern deep-sea carbonate sediments ( δ11B = 8.9 to 26.2%.). The variations of δ11B may be controlled by isotopic exchange of boron species in which 10B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. Carbonates with low δ11B values (~ 15%.) may indicate preferential incorporation of tetrahedral species, whereas the higher δ11B values (~30%.) may indicate (1) uptake of both boron species assuming equilibrium with seawater (2) preferential incorporation of B(OH) 4- from in situ high-pH internal fluids of organisms that are isolated from seawater. The B content and δ11B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 ± 0.9 × 10 10 g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 × 10 10 g/yr) and approximately half that of altered oceanic crust (14 × 10 10 g/yr). Thus, carbonates are an important sink for B in the oceans being ~20% of the total sinks. The preferential incorporation of 10B into calcium carbonate results in oceanic 11B-enrichment, estimated as 1.2 ± 0.3 × 10 12 per mil · g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record. The potential use of boron-isotope geochemistry in skeletons as a tracer for palaeoenvironments is demonstrated in Ostracoda and Foraminifera from the Gulf of Carpentaria, Australia. The δ11B values of glacial-age, buried skeletons (4.0 and 4.9%., respectively) are lower than that of their modern equivalents (17.6 and 13.3%., respectively). This may reflect a "terrestrial" boron-isotope signature of the water in the gulf during the Late Quaternary when it was isolated from the ocean.

Effect of Boron on the Strength and Toughness of Direct-Quenched Low-Carbon Niobium Bearing Ultra-High-Strength Martensitic Steel

NASA Astrophysics Data System (ADS)

Hannula, Jaakko; Kömi, Jukka; Porter, David A.; Somani, Mahesh C.; Kaijalainen, Antti; Suikkanen, Pasi; Yang, Jer-Ren; Tsai, Shao-Pu

2017-11-01

The effect of boron on the microstructures and mechanical properties of laboratory-control-rolled and direct-quenched 6-mm-thick steels containing 0.08 wt pct C and 0.02 wt pct Nb were studied. The boron contents were 24 ppm and a residual amount of 4 ppm. Two different finish rolling temperatures (FRTs) of 1093 K and 1193 K (820 °C and 920 °C) were used in the hot rolling trials to obtain different levels of pancaked austenite prior to DQ. Continuous cooling transformation (CCT) diagrams were constructed to reveal the effect of boron on the transformation behavior of these steels. Microstructural characterization was carried out using various microscopy techniques, such as light optical microscopy (LOM) and scanning electron microscopy-electron backscatter diffraction (SEM-EBSD). The resultant microstructures after hot rolling were mixtures of autotempered martensite and lower bainite (LB), having yield strengths in the range 918 to 1067 MPa with total elongations to fracture higher than 10 pct. The lower FRT of 1093 K (820 °C) produced better combinations of strength and toughness as a consequence of a higher degree of pancaking in the austenite. Removal of boron lowered the 34 J/cm2 Charpy-V impact toughness transition temperature from 206 K to 158 K (-67 °C to -115 °C) when the finishing rolling temperature of 1093 K (820 °C) was used without any loss in the strength values compared to the boron-bearing steel. This was due to the finer and more uniform grain structure in the boron-free steel. Contrary to expectations, the difference was not caused by the formation of borocarbide precipitates, as verified by transmission electron microscopy (TEM) investigations, but through the grain coarsening effect of boron.

Nanopores creation in boron and nitrogen doped polycrystalline graphene: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Izadifar, Mohammadreza; Abadi, Rouzbeh; Nezhad Shirazi, Ali Hossein; Alajlan, Naif; Rabczuk, Timon

2018-05-01

In the present paper, molecular dynamic simulations have been conducted to investigate the nanopores creation on 10% of boron and nitrogen doped polycrystalline graphene by silicon and diamond nanoclusters. Two types of nanoclusters based on silicon and diamond are used to investigate their effect for the fabrication of nanopores. Therefore, three different diameter sizes of the clusters with five kinetic energies of 10, 50, 100, 300 and 500 eV/atom at four different locations in boron or nitrogen doped polycrystalline graphene nanosheets have been perused. We also study the effect of 3% and 6% of boron doped polycrystalline graphene with the best outcome from 10% of doping. Our results reveal that the diamond cluster with diameter of 2 and 2.5 nm fabricates the largest nanopore areas on boron and nitrogen doped polycrystalline graphene, respectively. Furthermore, the kinetic energies of 10 and 50 eV/atom can not fabricate nanopores in some cases for silicon and diamond clusters on boron doped polycrystalline graphene nanosheets. On the other hand, silicon and diamond clusters fabricate nanopores for all locations and all tested energies on nitrogen doped polycrystalline graphene. The area sizes of nanopores fabricated by silicon and diamond clusters with diameter of 2 and 2.5 nm are close to the actual area size of the related clusters for the kinetic energy of 300 eV/atom in all locations on boron doped polycrystalline graphene. The maximum area and the average maximum area of nanopores are fabricated by the kinetic energy of 500 eV/atom inside the grain boundary at the center of the nanosheet and in the corner of nanosheet with diameters of 2 and 3 nm for silicon and diamond clusters on boron and nitrogen doped polycrystalline graphene.

Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

PubMed Central

Schoepf, Verena; McCulloch, Malcolm T.; Warner, Mark E.; Levas, Stephen J.; Matsui, Yohei; Aschaffenburg, Matthew D.; Grottoli, Andréa G.

2014-01-01

Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of seawater pH using boron isotopes should be uncompromised by short-term bleaching events. PMID:25396422

Short-term coral bleaching is not recorded by skeletal boron isotopes.

PubMed

Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

2014-01-01

Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of seawater pH using boron isotopes should be uncompromised by short-term bleaching events.

Boron epoxy rocket motor case program

NASA Technical Reports Server (NTRS)

Stang, D. A.

1971-01-01

Three 28-inch-diameter solid rocket motor cases were fabricated using 1/8 inch wide boron/epoxy tape. The cases had unequal end closures (4-1/8-inch-diameter forward flanges and 13-inch-diameter aft flanges) and metal attachment skirts. The flanges and skirts were titanium 6Al-4V alloy. The original design for the first case was patterned after the requirements of the Applications Technology Satellite apogee kick motor. The second and third cases were designed and fabricated to approximate the requirements of a small Applications Technology Satellite apogee kick motor. The program demonstrated the feasibility of designing and fabricating large-scale filament-wound solid propellant rocket motor cases with boron/epoxy tape.

Evaluation of a novel sodium borocaptate-containing unnatural amino acid as a boron delivery agent for neutron capture therapy of the F98 rat glioma.

PubMed

Futamura, Gen; Kawabata, Shinji; Nonoguchi, Naosuke; Hiramatsu, Ryo; Toho, Taichiro; Tanaka, Hiroki; Masunaga, Shin-Ichiro; Hattori, Yoshihide; Kirihata, Mitsunori; Ono, Koji; Kuroiwa, Toshihiko; Miyatake, Shin-Ichi

2017-01-23

Boron neutron capture therapy (BNCT) is a unique particle radiation therapy based on the nuclear capture reactions in boron-10. We developed a novel boron-10 containing sodium borocaptate (BSH) derivative, 1-amino-3-fluorocyclobutane-1-carboxylic acid (ACBC)-BSH. ACBC is a tumor selective synthetic amino acid. The purpose of this study was to assess the biodistribution of ACBC-BSH and its therapeutic efficacy following Boron Neutron Capture Therapy (BNCT) of the F98 rat glioma. We evaluated the biodistribution of three boron-10 compounds, ACBC-BSH, BSH and boronophenylalanine (BPA), in vitro and in vivo, following intravenous (i.v.) administration and intratumoral (i.t.) convection-enhanced delivery (CED) in F98 rat glioma bearing rats. For BNCT studies, rats were stratified into five groups: untreated controls, neutron-irradiation controls, BNCT with BPA/i.v., BNCT with ACBC-BSH/CED, and BNCT concomitantly using BPA/i.v. and ACBC-BSH/CED. In vitro, ACBC-BSH attained higher cellular uptake F98 rat glioma cells compared with BSH. In vivo biodistribution studies following i.v. administration and i.t. CED of ACBC-BSH attained significantly higher boron concentrations than that of BSH, but much lower than that of BPA. However, following convection enhanced delivery (CED), ACBC-BSH attained significantly higher tumor concentrations than BPA. The i.t. boron-10 concentrations were almost equal between the ACBC-BSH/CED group and BPA/i.v. group of rats. The tumor/brain boron-10 concentration ratio was higher with ACBC-BSH/CED than that of BPA/i.v. group. Based on these data, BNCT studies were carried out in F98 glioma bearing rats using BPA/i.v. and ACBC-BSH/CED as the delivery agents. The corresponding mean survival times were 37.4 ± 2.6d and 44.3 ± 8.0d, respectively, and although modest, these differences were statistically significant. Our findings suggest that further studies are warranted to evaluate ACBC-BSH/CED as a boron delivery agent.

First principle study of the electronic and magnetic properties of a single iron atomic chain encapsulated in boron nitrite nanotubes

NASA Astrophysics Data System (ADS)

Fathalian, Ali; Jalilian, Jaafar; Shahidi, Sahar

2011-11-01

The electronic and magnetic properties for a single Fe atom chain wrapped in armchair (n,n) boron nitride nanotubes (BNNTs) ( 4≤n≤6) are investigated through the density functional theory. By increasing the nanotube diameter, the magnetic moments, total magnetic moments and spin polarization of Fe@(n,n) systems are increased. We have calculated the majority and minority density of states (DOS) of armchair Fe@(6,6) BNNT. Our results show that the magnetic moment of the system come mostly from the Fe atom chain. The magnetic moment on an Fe atom, the total magnetic moment and spin polarization decrease by increasing the axial separation of the Fe atom chain for the Fe@(6,6) system. The Fe@(6,6) BNNT can be used in the magnetic nanodevices because of higher magnetic moment and spin polarization.

Effect of boron compounds on physical, mechanical, and fire properties of injection molded wood plastic composites

Treesearch

Nadir Ayrilmis; Turgay Akbulut; Turker Dundar; Robert H. White; Fatih Mengeloglu; Zeki Candan; Umit Buyuksari; Erkan Avci

2011-01-01

Physical, mechanical, and fire properties of the injection-molded wood flour/polypropylene composites (WPCs) incorporated with different levels of boron compounds, borax/boric acid (BX/BA) (0.5:0.5 wt %) and zinc borate (ZB) (4, 8, or 12 wt %) were investigated. The effect of the coupling agent loading (2, 4, or 6 wt %), maleic anhydride-grafted PP (MAPP), on the...

Recycling of subducted crustal components into carbonatite melts revealed by boron isotopes

NASA Astrophysics Data System (ADS)

Hulett, Samuel R. W.; Simonetti, Antonio; Rasbury, E. Troy; Hemming, N. Gary

2016-12-01

The global boron geochemical cycle is closely linked to recycling of geologic material via subduction processes that have occurred over billions of years of Earth’s history. The origin of carbonatites, unique melts derived from carbon-rich and carbonate-rich regions of the upper mantle, has been linked to a variety of mantle-related processes, including subduction and plume-lithosphere interaction. Here we present boron isotope (δ11B) compositions for carbonatites from locations worldwide that span a wide range of emplacement ages (between ~40 and ~2,600 Ma). Hence, they provide insight into the temporal evolution of their mantle sources for ~2.6 billion years of Earth’s history. Boron isotope values are highly variable and range between -8.6‰ and +5.5‰, with all of the young (<300 Ma) carbonatites characterized by more positive δ11B values (>-4.0‰), whereas most of the older carbonatite samples record lower B isotope values. Given the δ11B value for asthenospheric mantle of -7 +/- 1‰, the B isotope compositions for young carbonatites require the involvement of an enriched (crustal) component. Recycled crustal components may be sampled by carbonatite melts associated with mantle plume activity coincident with major tectonic events, and linked to past episodes of significant subduction associated with supercontinent formation.

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

NASA Astrophysics Data System (ADS)

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

2011-04-01

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

Effect of dietary boron on 5-fluorouracil induced oral mucositis in rats

PubMed Central

Aras, Mutan Hamdi; Sezer, Ufuk; Erkilic, Suna; Demir, Tuncer; Dagli, Seyda Nur

2013-01-01

Objective: The aim of this study was to evaluate the effect of boron on 5-fluorouracil (5-FU)–induced oral mucositis in rats. Materials and Methods: Sixty-four male Wistar albino rats were injected with 5-FU on days 1 and 3. The right cheek pouch mucosa was scratched with the tip of an 18-G needle, dragged twice in a linear movement, on days 3 and 5. The animals were randomly divided into two groups of 32: boron group (BG) and control group (CG). Rats in the CG did not receive any treatment, whereas the others were fed boron (3 mg·kg-1·day-1) by gavage. The animals were sacrificed on day 3 (n = 8), 6 (n = 8), 9 (n = 8), and 12 (n = 8), and the cheek pouch was removed for histopathological analysis. Results: On day 3, both groups showed necrosis and active inflammation, but the inflammation was mild in CG and moderate in BG. On day 6, both BG and CG showed necrosis; in the CG, there was moderate inflammation, and in the BG, there was severe inflammation and granulation tissue around the necrotic area. On day 9, re-epithelization began in both groups, and there were no differences between groups. Re-epithelization was complete in both groups on day 12. Conclusion: We found no beneficial effect of boron in healing oral mucositis. Additional research is warranted to elucidate the pathogenic inflammatory mechanisms involved in mucositis and the prophylactic and therapeutic roles of antioxidants. PMID:24926211

Dose-dependent Effect of Boric Acid on Myogenic Differentiation of Human Adipose-derived Stem Cells (hADSCs).

PubMed

Apdik, Hüseyin; Doğan, Ayşegül; Demirci, Selami; Aydın, Safa; Şahin, Fikrettin

2015-06-01

Boron, a vital micronutrient for plant metabolism, is not fully elucidated for embryonic and adult body development, and tissue regeneration. Although optimized amount of boron supplement has been shown to be essential for normal gestational development in zebrafish and frog and beneficial for bone regeneration in higher animals, effects of boron on myogenesis and myo-regeneration remains to be solved. In the current study, we investigated dose-dependent activity of boric acid on myogenic differentiation of human adipose-derived stem cells (hADSCs) using immunocytochemical, gene, and protein expression analysis. The results revealed that while low- (81.9 μM) and high-dose (819.6 μM) boron treatment increased myogenic gene expression levels such as myosin heavy chain (MYH), MyoD, myogenin, and desmin at day 4 of differentiation, high-dose treatment decreased myogenic-related gene and protein levels at day 21 of differentiation, confirmed by immunocytochemical analysis. The findings of the study present not only an understanding of boron's effect on myogenic differentiation but also an opportunity for the development of scaffolds to be used in skeletal tissue engineering and supplements for embryonic muscle growth. However, fine dose tuning and treatment period arranging are highly warranted as boron treatment over required concentrations and time might result in detrimental outcomes to myogenesis and myo-regeneration.

Mechanisms of boron removal from hydraulic fracturing wastewater by aluminum electrocoagulation.

PubMed

Sari, Mutiara Ayu; Chellam, Shankararaman

2015-11-15

Boron uptake from highly saline hydraulic fracturing wastewater by freshly precipitated amorphous Al(OH)3 precipitates is due to ligand exchange and complexation with surface hydroxyl groups. Consequently, aluminum electrocoagulation can be a feasible approach to remove boron from flowback/produced water. Actual hydraulic fracturing wastewater containing ∼120mg/L boron from the Eagle Ford shale play was employed. Electrocoagulation was performed over a range of aluminum dosages (0-1350mg/L), pH 6.4 and 8, and high current densities (20-80mA/cm(2)) using a cylindrical aluminum anode encompassed by a porous cylindrical 316-stainless steel cathode. Direct measurements of boron uptake along with its chemical state and coordination were made using Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) and X-Ray Photoelectron Spectroscopy. Boron removal increased monotonically with aluminum dosage and was higher at pH 8, but remained relatively constant at ⩾20mA/cm(2). Chloride ions induced anodic pitting and super-Faradaic (131% efficiency) aluminum dissolution and their electrooxidation produced free chlorine. ATR-FTIR suggested outer-sphere and inner-sphere complexation of trigonal B(OH)3 with Al(OH)3, which was confirmed by the BO bond shifting toward lower binding energies in XPS. Severe AlO interferences precluded evidence for tetrahedral B(OH)4(-) complexation. No evidence for co-precipitation was obtained. Copyright © 2015 Elsevier Inc. All rights reserved.

Boron removal by electrocoagulation and recovery.

PubMed

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

2014-03-15

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

Boron containing multilayer coatings and method of fabrication

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1997-01-01

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

Shear-Assisted Production of Few-Layer Boron Nitride Nanosheets by Supercritical CO2 Exfoliation and Its Use for Thermally Conductive Epoxy Composites.

PubMed

Tian, Xiaojuan; Li, Yun; Chen, Zhuo; Li, Qi; Hou, Liqiang; Wu, Jiaye; Tang, Yushu; Li, Yongfeng

2017-12-19

Boron nitride nanosheets (BNNS) hold the similar two-dimensional structure as graphene and unique properties complementary to graphene, which makes it attractive in application ranging from electronics to energy storage. The exfoliation of boron nitride (BN) still remains challenge and hinders the applications of BNNS. In this work, the preparation of BNNS has been realized by a shear-assisted supercritical CO 2 exfoliation process, during which supercritical CO 2 intercalates and diffuses between boron nitride layers, and then the exfoliation of BN layers is obtained in the rapid depressurization process by overcoming the van der Waals forces. Our results indicate that the bulk boron nitride has been successfully exfoliated into thin nanosheets with an average 6 layers. It is found that the produced BNNS is well-dispersed in isopropyl alcohol (IPA) with a higher extinction coefficient compared with the bulk BN. Moreover, the BNNS/epoxy composite used as thermal interface materials has been prepared. The introduction of BNNS results in a 313% enhancement in thermal conductivity. Our results demonstrate that BNNS produced by supercritical CO 2 exfoliation show great potential applications for heat dissipation of high efficiency electronics.

Boronic acid-containing CXCR1/2 antagonists: optimization of metabolic stability, in vivo evaluation, and a proposed receptor binding model

PubMed Central

Maeda, Dean Y.; Peck, Angela M.; Schuler, Aaron D.; Quinn, Mark T.; Kirpotina, Liliya N.; Wicomb, Winston N.; Auten, Richard L.; Gundla, Rambabu; Zebala, John A.

2015-01-01

Blockade of undesired neutrophil migration to sites of inflammation remains an area of substantial pharmaceutical interest. To effect this blockade, a validated therapeutic target is antagonism of the chemokine receptor CXCR2. Herein we report the discovery of 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide 6, an antagonist with activity at both CXCR1 and CXCR2 receptors (IC50 values 31 and 21 nM, respectively). Compound 6 exhibited potent inhibition of neutrophil influx in a rat model of pulmonary inflammation, and is hypothesized to interact with a unique intracellular binding site on CXCR2. Compound 6 (SX-576) is undergoing further investigation as a potential therapy for pulmonary inflammation. PMID:25933594

In situ TEM study of electron-beam radiation induced boron diffusion and effects on phase and microstructure evolution in nanostructured CoFeB/SiO2 thin film

NASA Astrophysics Data System (ADS)

Liu, B. H.; Teo, H. W.; Mo, Z. H.; Mai, Z. H.; Lam, J.; Xue, J. M.; Zhao, Y. Z.; Tan, P. K.

2017-01-01

Using in situ transmission electron microscopy (TEM), we studied boron diffusion and segregation in CoFeB/SiO2 nanostructured thin film stacks. We also investigated how these phenomena affected the phase and microstructure of CoFeB thin films under electron beam irradiation at 300 kV. A unique phase transformation was observed in CoFeB thin films under high-dose electron irradiation, from a polycrystalline Co3Fe to a unilateral amorphous phase of Co3Fe and nanocrystalline FexCo23-xB6. The unilateral amorphization of the Co3Fe film showed an electron-dose-rate sensitivity with a threshold dose rate. Detailed in situ TEM studies revealed that the unilateral amorphization of the Co3Fe film arose from boron segregation at the bottom of the Co3Fe thin film induced by radiation-enhanced diffusion of boron atoms that were displaced by electron knock-on effects. The radiation-induced nanocrystallization of FexCo23-xB6 was also found to be dose-rate sensitive with a higher electron beam current leading to earlier nucleation and more rapid grain growth. The nanocrystallization of FexCo23-xB6 occurred preferentially at the CoFeB/SiO2 interface. Kinetic studies by in situ TEM revealed the surface crystallization and diffusion-controlled nucleation and grain growth mechanisms. The radiation-enhanced atomic diffusivity and high-concentration of radiation-induced point defects at the Co3Fe/SiO2 interface enhanced the local short-range ordering of Fe, Co, and B atoms, favoring nucleation and grain growth of FexCo23-xB6 at the interface.

[Determination of diborane in the air of workplace by ICP-AES].

PubMed

Ding, Chun-Guang; Zhang, Jing; Yan, Hui-Fang

2011-06-01

A sampling method was established to collect diborane in the air of workplace and an ICP-AES method was developed to determine the Boron in desorbed solution. Diborane in the air of workplace was collected by solid sorbent tube filled with oxidant impregnated activated carbon. The adsorbed diborane was desorbed into 3% H2O2 aqueous, and then the desorbed Boron was determined by ICP-AES. The sampling efficiency of this method was 99.6% with the desorption efficiency of diborane with 5.660 microg and 56.6 microg spiked were 90.9% and 99.5%, respectively. Both the intra-and inter-precision RSD were less than 8%. The standard curve of this method ranged from 0.1 to 10.0 microg/ml (Boron), and the LOD and LOQ were 0.011 mg/m3 and 0.035 mg/m3 (15L samples) respectively. The method established was suitable for diborane sampling and determination in the air of workplace.

Precision Measurement of the Boron to Carbon Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the International Space Station

NASA Astrophysics Data System (ADS)

Aguilar, M.; Ali Cavasonza, L.; Ambrosi, G.; Arruda, L.; Attig, N.; Aupetit, S.; Azzarello, P.; Bachlechner, A.; Barao, F.; Barrau, A.; Barrin, L.; Bartoloni, A.; Basara, L.; Başeǧmez-du Pree, S.; Battarbee, M.; Battiston, R.; Becker, U.; Behlmann, M.; Beischer, B.; Berdugo, J.; Bertucci, B.; Bindel, K. F.; Bindi, V.; Boella, G.; de Boer, W.; Bollweg, K.; Bonnivard, V.; Borgia, B.; Boschini, M. J.; Bourquin, M.; Bueno, E. F.; Burger, J.; Cadoux, F.; Cai, X. D.; Capell, M.; Caroff, S.; Casaus, J.; Castellini, G.; Cervelli, F.; Chae, M. J.; Chang, Y. H.; Chen, A. I.; Chen, G. M.; Chen, H. S.; Cheng, L.; Chou, H. Y.; Choumilov, E.; Choutko, V.; Chung, C. H.; Clark, C.; Clavero, R.; Coignet, G.; Consolandi, C.; Contin, A.; Corti, C.; Creus, W.; Crispoltoni, M.; Cui, Z.; Dai, Y. M.; Delgado, C.; Della Torre, S.; Demakov, O.; Demirköz, M. B.; Derome, L.; Di Falco, S.; Dimiccoli, F.; Díaz, C.; von Doetinchem, P.; Dong, F.; Donnini, F.; Duranti, M.; D'Urso, D.; Egorov, A.; Eline, A.; Eronen, T.; Feng, J.; Fiandrini, E.; Finch, E.; Fisher, P.; Formato, V.; Galaktionov, Y.; Gallucci, G.; García, B.; García-López, R. J.; Gargiulo, C.; Gast, H.; Gebauer, I.; Gervasi, M.; Ghelfi, A.; Giovacchini, F.; Goglov, P.; Gómez-Coral, D. M.; Gong, J.; Goy, C.; Grabski, V.; Grandi, D.; Graziani, M.; Guo, K. H.; Haino, S.; Han, K. C.; He, Z. H.; Heil, M.; Hoffman, J.; Hsieh, T. H.; Huang, H.; Huang, Z. C.; Huh, C.; Incagli, M.; Ionica, M.; Jang, W. Y.; Jinchi, H.; Kang, S. C.; Kanishev, K.; Kim, G. N.; Kim, K. S.; Kirn, Th.; Konak, C.; Kounina, O.; Kounine, A.; Koutsenko, V.; Krafczyk, M. S.; La Vacca, G.; Laudi, E.; Laurenti, G.; Lazzizzera, I.; Lebedev, A.; Lee, H. T.; Lee, S. C.; Leluc, C.; Li, H. S.; Li, J. Q.; Li, J. Q.; Li, Q.; Li, T. X.; Li, W.; Li, Y.; Li, Z. H.; Li, Z. Y.; Lim, S.; Lin, C. H.; Lipari, P.; Lippert, T.; Liu, D.; Liu, Hu; Lordello, V. D.; Lu, S. Q.; Lu, Y. S.; Luebelsmeyer, K.; Luo, F.; Luo, J. Z.; Lv, S. S.; Machate, F.; Majka, R.; Mañá, C.; Marín, J.; Martin, T.; Martínez, G.; Masi, N.; Maurin, D.; Menchaca-Rocha, A.; Meng, Q.; Mikuni, V. M.; Mo, D. C.; Morescalchi, L.; Mott, P.; Nelson, T.; Ni, J. Q.; Nikonov, N.; Nozzoli, F.; Oliva, A.; Orcinha, M.; Palmonari, F.; Palomares, C.; Paniccia, M.; Pauluzzi, M.; Pensotti, S.; Pereira, R.; Picot-Clemente, N.; Pilo, F.; Pizzolotto, C.; Plyaskin, V.; Pohl, M.; Poireau, V.; Putze, A.; Quadrani, L.; Qi, X. M.; Qin, X.; Qu, Z. Y.; Räihä, T.; Rancoita, P. G.; Rapin, D.; Ricol, J. S.; Rosier-Lees, S.; Rozhkov, A.; Rozza, D.; Sagdeev, R.; Sandweiss, J.; Saouter, P.; Schael, S.; Schmidt, S. M.; Schulz von Dratzig, A.; Schwering, G.; Seo, E. S.; Shan, B. S.; Shi, J. Y.; Siedenburg, T.; Son, D.; Song, J. W.; Sun, W. H.; Tacconi, M.; Tang, X. W.; Tang, Z. C.; Tao, L.; Tescaro, D.; Ting, Samuel C. C.; Ting, S. M.; Tomassetti, N.; Torsti, J.; Türkoǧlu, C.; Urban, T.; Vagelli, V.; Valente, E.; Vannini, C.; Valtonen, E.; Vázquez Acosta, M.; Vecchi, M.; Velasco, M.; Vialle, J. P.; Vitale, V.; Vitillo, S.; Wang, L. Q.; Wang, N. H.; Wang, Q. L.; Wang, X.; Wang, X. Q.; Wang, Z. X.; Wei, C. C.; Weng, Z. L.; Whitman, K.; Wienkenhöver, J.; Wu, H.; Wu, X.; Xia, X.; Xiong, R. Q.; Xu, W.; Yan, Q.; Yang, J.; Yang, M.; Yang, Y.; Yi, H.; Yu, Y. J.; Yu, Z. Q.; Zeissler, S.; Zhang, C.; Zhang, J.; Zhang, J. H.; Zhang, S. D.; Zhang, S. W.; Zhang, Z.; Zheng, Z. M.; Zhu, Z. Q.; Zhuang, H. L.; Zhukov, V.; Zichichi, A.; Zimmermann, N.; Zuccon, P.; AMS Collaboration

2016-12-01

Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B /C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B /C spectral index is reported for the first time. The B /C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B /C ratio is well described by a single power law RΔ with index Δ =-0.333 ±0.014 (fit ) ±0.005 (syst ) , in good agreement with the Kolmogorov theory of turbulence which predicts Δ =-1 /3 asymptotically.

Methods of forming boron nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 boronmore » nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.« less

Molecular complexes of alprazolam with carboxylic acids, boric acid, boronic acids, and phenols. Evaluation of supramolecular heterosynthons mediated by a triazole ring.

PubMed

Varughese, Sunil; Azim, Yasser; Desiraju, Gautam R

2010-09-01

A series of molecular complexes, both co-crystals and salts, of a triazole drug-alprazolam-with carboxylic acids, boric acid, boronic acids, and phenols have been analyzed with respect to heterosynthons present in the crystal structures. In all cases, the triazole ring behaves as an efficient hydrogen bond acceptor with the acidic coformers. The hydrogen bond patterns exhibited with aromatic carboxylic acids were found to depend on the nature and position of the substituents. Being a strong acid, 2,6-dihydroxybenzoic acid forms a salt with alprazolam. With aliphatic dicarboxylic acids alprazolam forms hydrates and the water molecules play a central role in synthon formation and crystal packing. The triazole ring makes two distinct heterosynthons in the molecular complex with boric acid. Boronic acids and phenols form consistent hydrogen bond patterns, and these are seemingly independent of the substitutional effects. Boronic acids form noncentrosymmetric cyclic synthons, while phenols form O--H...N hydrogen bonds with the triazole ring.

Determination of boron in uranium aluminum silicon alloy by spectrophotometry and estimation of expanded uncertainty in measurement

NASA Astrophysics Data System (ADS)

Ramanjaneyulu, P. S.; Sayi, Y. S.; Ramakumar, K. L.

2008-08-01

Quantification of boron in diverse materials of relevance in nuclear technology is essential in view of its high thermal neutron absorption cross section. A simple and sensitive method has been developed for the determination of boron in uranium-aluminum-silicon alloy, based on leaching of boron with 6 M HCl and H 2O 2, its selective separation by solvent extraction with 2-ethyl hexane 1,3-diol and quantification by spectrophotometry using curcumin. The method has been evaluated by standard addition method and validated by inductively coupled plasma-atomic emission spectroscopy. Relative standard deviation and absolute detection limit of the method are 3.0% (at 1 σ level) and 12 ng, respectively. All possible sources of uncertainties in the methodology have been individually assessed, following the International Organization for Standardization guidelines. The combined uncertainty is calculated employing uncertainty propagation formulae. The expanded uncertainty in the measurement at 95% confidence level (coverage factor 2) is 8.840%.

Eggshell membrane as a novel bio sorbent for remediation of boron from desalinated water.

PubMed

Al-Ghouti, Mohammad A; Khan, Mariam

2018-02-01

This study investigated the use of eggshell membrane (ESM) as a bio-sorbent and the effect of temperature, pH, and initial concentration on its efficiency. Furthermore, by altering the chemical composition, modified eggshell membrane (MESM) was prepared, and its efficiency was compared with the ESM. Results showed that the adsorption of boron preferred an acidic condition; pH 6 at 35 °C. In addition, the positive value of ΔH° suggested that the reaction favored endothermic pathway, while the negative value for ΔG° further suggested that the adsorption process was spontaneous. Furthermore, the ESM could adsorb 97% of boron, while MESM was able to adsorb 95%. From the Fourier transform infrared (FTIR), different functional groups were recorded on the surface of the ESM and MESM, and they played key role in the boron adsorption mechanisms. Linear Freundlich model was suggested to best describe the experimental data with 99.4% correlation coefficient. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and spectroscopic properties of some new difluoroboron bis-β-diketonate derivatives.

PubMed

Pi, Yan; Wang, Dun-Jia; Liu, Hua; Hu, Yan-Jun; Wei, Xian-Hong; Zheng, Jing

2014-10-15

Six new bis-β-diketones (RCOCH2CO-C7H7N-COCH2COR) were synthesized from 3,5-diacetyl-2,6-dimethylpyridine via Claisen condensation with the corresponding esters, and then reacted with boron trifluoride etherate to afford difluoroboron bis-β-diketonate derivatives. Their spectroscopic properties were investigated by UV-vis, FTIR, (1)H NMR and fluorescence spectroscopic techniques. It was found that these boron complexes exhibited violet or blue fluorescence emission at 422-445nm and possessed high extinction coefficients. The results indicate that the extending π-conjugation can increase the fluorescence intensity and quantum yield for these boron complexes. Especially, the compound 2b displayed the stronger fluorescence intensity and the highest fluorescence quantum yield (Φu=0.94) in these boron compounds. However, compounds 2c and 2d had the lower fluorescence intensity and quantum yield as a result of the heavy atom effect of the chlorine atom in the molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and spectroscopic properties of some new difluoroboron bis-β-diketonate derivatives

NASA Astrophysics Data System (ADS)

Pi, Yan; Wang, Dun-Jia; Liu, Hua; Hu, Yan-Jun; Wei, Xian-Hong; Zheng, Jing

2014-10-01

Six new bis-β-diketones (RCOCH2CO-C7H7N-COCH2COR) were synthesized from 3,5-diacetyl-2,6-dimethylpyridine via Claisen condensation with the corresponding esters, and then reacted with boron trifluoride etherate to afford difluoroboron bis-β-diketonate derivatives. Their spectroscopic properties were investigated by UV-vis, FTIR, 1H NMR and fluorescence spectroscopic techniques. It was found that these boron complexes exhibited violet or blue fluorescence emission at 422-445 nm and possessed high extinction coefficients. The results indicate that the extending π-conjugation can increase the fluorescence intensity and quantum yield for these boron complexes. Especially, the compound 2b displayed the stronger fluorescence intensity and the highest fluorescence quantum yield (Φu = 0.94) in these boron compounds. However, compounds 2c and 2d had the lower fluorescence intensity and quantum yield as a result of the heavy atom effect of the chlorine atom in the molecules.

High-Performance Organic Light-Emitting Diode with Substitutionally Boron-Doped Graphene Anode.

PubMed

Wu, Tien-Lin; Yeh, Chao-Hui; Hsiao, Wen-Ting; Huang, Pei-Yun; Huang, Min-Jie; Chiang, Yen-Hsin; Cheng, Chien-Hong; Liu, Rai-Shung; Chiu, Po-Wen

2017-05-03

The hole-injection barrier between the anode and the hole-injection layer (HIL) is of critical importance to determine the device performance of organic light-emitting diodes (OLEDs). Here, we report on a record-high external quantum efficiency (EQE) (24.6% in green phosphorescence) of OLEDs fabricated on both rigid and flexible substrates, with the performance enhanced by the use of nearly defect-free and high-mobility boron-doped graphene as an effective anode and hexaazatriphenylene hexacarbonitrile as a new type of HIL. This new structure outperforms the existing graphene-based OLEDs, in which MoO 3 , AuCl 3 , or bis(trifluoromethanesulfonyl)amide are typically used as a doping source for the p-type graphene. The improvement of the OLED performance is attributed mainly to the appreciable increase of the hole conductivity in the nearly defect-free boron-doped monolayer graphene, along with the high work function achieved by the use of a newly developed hydrocarbon precursor containing boron in the graphene growth by chemical vapor deposition.

Practical calculation method to estimate the absolute boron concentration in tissues using 18F-FBPA PET.

PubMed

Watabe, Tadashi; Hanaoka, Kohei; Naka, Sadahiro; Kanai, Yasukazu; Ikeda, Hayato; Aoki, Masanao; Shimosegawa, Eku; Kirihata, Mitsunori; Hatazawa, Jun

2017-07-01

The purpose of this study was to establish a practical method to estimate the absolute boron concentrations in the tissues based on the standardized uptake values (SUVs) after administration of 4-borono-phenylalanine (BPA) using 4-borono-2- 18 F-fluoro-phenylalanine ( 18 F-FBPA) PET. Rat xenograft models of C6 glioma (n = 7, body weight 241 ± 28.0 g) were used for the study. PET was performed 60 min after intravenous injection of 18 F-FBPA (30.5 ± 0.7 MBq). After the PET scanning, BPA-fructose (167.3 ± 18.65 mg/kg) was administered by slow intravenous injection to the same subjects. The rats were killed 60 min after the BPA injection and tissue samples were collected from the major organs and tumors. The absolute boron concentrations (unit: ppm) in the samples were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The boron concentrations in the tissues/tumors were also estimated from the 18 F-FBPA PET images using the following formula: estimated absolute boron concentration (ppm) = 0.0478 × [BPA dose (mg/kg)] × SUV. The measured absolute boron concentrations (mBC) by ICP-OES and the estimated boron concentrations (eBC) from the PET images were compared. The percent difference between the mBC and eBC calculated based on the SUV max was -5.2 ± 21.1% for the blood, -9.4 ± 22.3% for the brain, 1.6 ± 21.3% for the liver, -14.3 ± 16.8% for the spleen, -9.5 ± 27.5% for the pancreas, and 3.4 ± 43.2% for the tumor. Relatively large underestimation was observed for the lung (-48.4 ± 16.2%), small intestine (-37.8 ± 19.3%) and large intestine (-33.9 ± 11.0%), due to the partial volume effect arising from the air or feces contained in these organs. In contrast, relatively large overestimation was observed for the kidney (34.3 ± 29.3%), due to the influence of the high uptake in urine. The absolute boron concentrations in tissues/tumors can be estimated from the SUVs on 18 F-FBPA PET using a practical formula. Caution must be exercised in interpreting the estimated boron concentrations in the lung, small intestine and large intestine, to prevent the adverse effects of overexposure, which could occur due to underestimation by partial volume effect using PET.

Elevated temperature properties of boron/aluminum composites

NASA Technical Reports Server (NTRS)

Sullivan, P. G.

1978-01-01

The high temperature properties of boron/aluminum composites, fabricated by an air diffusion bonding technique utilizing vacuum-bonded monolayer tape are reported. Seventeen different combinations of matrix alloy, reinforcement diameter, reinforcement volume percent, angle-ply and matrix enhancement (i.e. titanium cladding and interleaves) were fabricated, inspected, and tested. It is shown that good to excellent mechanical properties could be obtained for air-bonded boron/aluminum composites and that these properties did not decrease significantly up to a test temperature of at least 260 C. Composites made with 8 mil B/W fiber show a much greater longitudinal strength dependence on volume percent fiber than composites made with 5.6 mil fiber. The addition of titanium caused difficulties in composite bonding and yielded composites with reduced strength.

Raman Scattering by Crystals of Rare-Earth Hexaborides with Different Isotopes of Boron

NASA Astrophysics Data System (ADS)

Markov, Yu. F.; Gurin, V. N.; Ponkratov, K. V.

2018-04-01

Monocrystals of lanthanum hexaboride LaB6 containing both natural boron and its isotopes 10B and 11B have been produced using the solution-melt method. Polyelement hexaboride rare-earths have been grown and the corresponding ceramics have been synthesized for the first time. All these crystals have been studied by means of various techniques, generally using Raman scattering. The Raman spectra attributed to various spectral lines corresponding to nonanalyzable representations have been obtained and interpreted. Frequencies and half-widths of spectral lines have been obtained, the removal of degeneracy and the development of respective splitting of degenerate oscillations induced by defects, mainly by boron isotope inclusions, have been identified. The influence of defects on the Raman spectra has been determined.

Planar dicyclic B{sub 6}S{sub 6}, B{sub 6}S{sub 6}{sup −}, and B{sub 6}S{sub 6}{sup 2−} clusters: Boron sulfide analogues of naphthalene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Da-Zhi; Bai, Hui; Ou, Ting

2015-01-07

Inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs) are of current interest in chemistry. Based upon global structural searches and B3LYP and CCSD(T) calculations, we present herein the perfectly planar dicyclic boron sulfide clusters: D{sub 2h} B{sub 6}S{sub 6} (1, {sup 1}A{sub g}), D{sub 2h} B{sub 6}S{sub 6}{sup −} (2, {sup 2}B{sub 3u}), and D{sub 2h} B{sub 6}S{sub 6}{sup 2−} (3, {sup 1}A{sub g}). These are the global minima of the systems, being at least 0.73, 0.81, and 0.53 eV lower in energy, respectively, than their alternative isomers at the CCSD(T) level. The D{sub 2h} structures feature twin B{submore » 3}S{sub 2} five-membered rings, which are fused together via a B{sub 2} unit and terminated by two BS groups. Bonding analyses show that the closed-shell B{sub 6}S{sub 6}{sup 2−} (3) cluster possesses 10 delocalized π electrons, closely analogous to the bonding pattern of the aromatic naphthalene C{sub 10}H{sub 8}. The B{sub 6}S{sub 6}{sup −} (2) and B{sub 6}S{sub 6} (1) species are readily obtained upon removal of one or two π electrons from B{sub 6}S{sub 6}{sup 2−} (3). The results build a new analogous relationship between boron sulfide clusters and their PAH counterparts. The B{sub 6}S{sub 6}{sup −} (2) monoanion and B{sub 6}S{sub 6}{sup 2−} (3) dianion can be effectively stabilized in neutral LiB{sub 6}S{sub 6} and Li{sub 2}B{sub 6}S{sub 6} salts, respectively.« less

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vengosh, A.; Chivas, A.R.; McCulloch, M.T.

1991-10-01

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

Not all boronic acids with a five-membered cycle induce tremor, neuronal damage and decreased dopamine.

PubMed

Pérez-Rodríguez, Maribel; García-Mendoza, Esperanza; Farfán-García, Eunice D; Das, Bhaskar C; Ciprés-Flores, Fabiola J; Trujillo-Ferrara, José G; Tamay-Cach, Feliciano; Soriano-Ursúa, Marvin A

2017-09-01

Several striatal toxins can be used to induce motor disruption. One example is MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), whose toxicity is accepted as a murine model of parkinsonism. Recently, 3-Thienylboronic acid (3TB) was found to produce motor disruption and biased neuronal damage to basal ganglia in mice. The aim of this study was to examine the toxic effects of four boronic acids with a close structural relationship to 3TB (all having a five-membered cycle), as well as boric acid and 3TB. These boron-containing compounds were compared to MPTP regarding brain access, morphological disruption of the CNS, and behavioral manifestations of such disruption. Data was collected through acute toxicity evaluations, motor behavior tests, necropsies, determination of neuronal survival by immunohistochemistry, Raman spectroscopic analysis of brain tissue, and HPLC measurement of dopamine in substantia nigra and striatum tissue. Each compound showed a distinct profile for motor disruption. For example, motor activity was not disrupted by boric acid, but was decreased by two boronic acids (caused by a sedative effect). 3TB, 2-Thienyl and 2-furanyl boronic acid gave rise to shaking behavior. The various manifestations generated by these compounds can be linked, in part, to different levels of dopamine (measured by HPLC) and degrees of neuronal damage in the basal ganglia and cerebellum. Clearly, motor disruption is not induced by all boronic acids with a five-membered cycle as substituent. Possible explanations are given for the diverse chemico-morphological changes and degrees of disruption of the motor system, considering the role of boron and the structure-toxicity relationship. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystalline boron nitride aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.

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

Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model.

PubMed

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%.

Application of a unique test design to determine the chronic toxicity of boron to the aquatic worm Lumbriculus variegatus and fatmucket mussel Lampsilis siliquoidea.

PubMed

Hall, Scott; Lockwood, Rick; Harrass, Michael C

2014-01-01

The chronic (21- and 28-day) toxicity of boron was determined for two freshwater benthic macroinvertebrates: the fatmucket mussel Lampsilis siliquoidea and the aquatic worm Lumbriculus variegatus. The rapid depletion of boric acid from spiked sediments in tests using flow-through overlying waters was addressed by constant addition of boric acid to overlying water at concentrations matching those of the targeted porewater exposures. This proved highly successful in maintaining constant whole-sediment and sediment porewater boron concentrations. Boron sublethal 25 % inhibition concentration values based on porewater concentrations were 25.9 mg B/L (L. variegatus) and 38.5 mg B/L (L. siliquoidea), indicating similar test organism sensitivity. Expressed as dry whole-sediment values, the respective L. variegatus and L. siliquoidea sublethal (growth) IC25 values for whole-sediment exposures were 235.5 mg B/kg sediment dry weight (dw) and 310.6 mg B/kg dw. The worm lethality-based end points indicated greater sensitivity than the sublethal end points, bringing into question the validity of a "lethality" end point for L. variegatus given its fragmentation mode of reproduction. For comparison, water-only mussel exposures were tested resulting in an IC25 value of 34.6 mg B/L, which was within 20 % of the porewater value. This suggests that the primary route of boron exposure was through the aqueous phase. The results of this study indicated that for test materials that are readily water soluble, standard sediment test designs may be unsuitable, but water-only exposures can provide toxicological data representative of sediment tests.

Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model

PubMed Central

Heber, Elisa M.; Hawthorne, M. Frederick; Kueffer, Peter J.; Garabalino, Marcela A.; Thorp, Silvia I.; Pozzi, Emiliano C. C.; Hughes, Andrea Monti; Maitz, Charles A.; Jalisatgi, Satish S.; Nigg, David W.; Curotto, Paula; Trivillin, Verónica A.; Schwint, Amanda E.

2014-01-01

The application of boron neutron capture therapy (BNCT) mediated by liposomes containing 10B-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%. PMID:25349432

Boron content and isotopic composition of ocean basalts: Geochemical and cosmochemical implications

NASA Astrophysics Data System (ADS)

Chaussidon, Marc; Jambon, Albert

1994-02-01

Ion microprobe determination of boron content and delta B-11 values has been performed for a set of 40 oceanic basalt glasses (N-MORB, E-MORB, BABB and OIB) whose chemical characteristics (major and trace elements and isotopic ratios) are well documented. Boron contents, determined at +/- 10% relative, range from 0.34 to 0.74 ppm in N-MORB, whereas E-MORB, BABB and OIB extend to higher concentrations (0.5-2.4 ppm). After correction for crystal fractionation, this range is reduced to 0.5-1.3 ppm. N-MORB and E-MORB also exhibit different B/K ratios, 1.0 +/- 0.3 x 10(exp -3) and 0.2 to 1.4 x 10(exp -3) respectively. This can be interpreted as resulting from the incorporation into the upper mantle of a K-rich and B-poor component (e.g., subducted oceanic crust having lost most of its initial boron). Delta B-11 values range between -7.40 +/- 2 and +0.6 +/- 2 per mill, with no significant difference between N-MORB, E-MORB, OIB or BABB. The Hawaiian samples define a strong linear correlation between boron contents, delta B-11 values, MgO and water contents and delta D values. This is interpreted as resulting from assimilation-fractionation processes which occurred within a water-rich oceanic crust, and which produced high delta B-11 values associated with high delta D values. The low level of B-11 enrichment in the upper mantle constraints the amount of boron reinjected by subduction to a maximum of about 2% of the boron present in the subducted slab. This in turn corresponds to a maximum net Boron transfer of about 3 x 10(exp 10) g/a towards the surface reservoirs. Finally, a boron content of 0.25 +/- 0.1 ppm is estimated for the bulk silicate Earth (i.e., primitive mantle), corresponding to a depletion factor relative to C1 chondrites of about 0.15 and suggesting that B was moderately volatile upon terrestrial accretion.

Semiconductor-insulator transition in a YbB6 nanowire with boron vacancy

NASA Astrophysics Data System (ADS)

Han, Wei; Wang, Zhen; Li, Qidong; Lian, Xin; Liu, Xudong; Fan, Qinghua; Zhao, Yanming

2018-06-01

In this paper, we report the study of transport and magnetic properties of ytterbium hexaboride (YbB6) nanowires grown by a low trigger-temperature (200-240 °C) solid state method. The temperature dependence of resistivity shows that the YbB6 nanowire undergoes a semiconductor-insulator transition (SIT) below 20 K with an activation energy ΔE of 1 meV. The value of ρ at 2 K reaches 49 times the value of ρ at 300 K (ρ2 K/ρ300 K = 49). The observed non-saturating magnetoresistance (MR) has a linear relationship with B2. The anomalous electronic transport in the YbB6 nanowire can be explained by the mixed valence of Yb ions due to the boron deficiency supporting by the X-ray photoelectron spectroscopy (XPS) and paramagnetic magnetization.

Boronic acid-containing CXCR1/2 antagonists: Optimization of metabolic stability, in vivo evaluation, and a proposed receptor binding model.

PubMed

Maeda, Dean Y; Peck, Angela M; Schuler, Aaron D; Quinn, Mark T; Kirpotina, Liliya N; Wicomb, Winston N; Auten, Richard L; Gundla, Rambabu; Zebala, John A

2015-06-01

Blockade of undesired neutrophil migration to sites of inflammation remains an area of substantial pharmaceutical interest. To effect this blockade, a validated therapeutic target is antagonism of the chemokine receptor CXCR2. Herein we report the discovery of 6-(2-boronic acid-5-trifluoromethoxy-benzylsulfanyl)-N-(4-fluoro-phenyl)-nicotinamide 6, an antagonist with activity at both CXCR1 and CXCR2 receptors (IC50 values 31 and 21 nM, respectively). Compound 6 exhibited potent inhibition of neutrophil influx in a rat model of pulmonary inflammation, and is hypothesized to interact with a unique intracellular binding site on CXCR2. Compound 6 (SX-576) is undergoing further investigation as a potential therapy for pulmonary inflammation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Energetic Materials and Metals Contamination at CFB/ASU Wainwirght, Alberta Phase 1

DTIC Science & Technology

2008-11-01

Edmonton, Alberta). Metals analyzed for this study were silver (Ag), aluminium (Al), arsenic (As), boron (B), barium (Ba), beryllium (Be), bismuth 4...selenium (Se), antimony (Sb), tin (Sn), strontium (Sr), tellurium (Te), titanium (Ti), thallium (Tl), uranium (U), vanadium (V), zinc (Zn), and...mg/kg mg/kg mg/kg Aluminium - 9070 1040 Antimony 40 2 1 Arsenic 12 7 13.6 Barium 2000 177 73.4 Beryllium 8 40 40 Bismuth - 20 20 Boron - 10

Novel Carboranyl Derivatives of Nucleoside Mono- and Diphosphites and Phosphonates: A Synthetic Investigation

PubMed Central

Vyakaranam, Kamesh; Hosmane, Narayan S.

2004-01-01

A number of nucleoside mono- and diphosphites and phosphonates containing 1,2-dicarbadodecaborane (12) (la-6b) at 5'-position of the sugar moiety have been synthesized in good yields. Experimental details along with the spectroscopic and analytical data, supporting the formation of the title compounds, are presented. These constitute a new generation of boron compounds that are envisioned to be useful in cancer treatment via Boron Neutron Capture Therapy (BNCT). PMID:18365067

Controlling the charge transfer in phenylene-bridged borylene-amine pi-conjugated systems.

PubMed

Proń, Agnieszka; Zhou, Gang; Norouzi-Arasi, Hassan; Baumgarten, Martin; Müllen, Klaus

2009-08-20

Novel boron-nitrogen-containing pi-conjugated compounds 3,3'- and 4,4'-((2,4,6-triisopropylphenyl)borylene)bis(N,N-diarylbenzenamine) (1-2), m- and p-phenylene bridged to the boron center, respectively, have been synthesized and characterized. Optical studies by means of UV-vis absorption and emission measurements as well as DFT calculations reveal a different charge transfer behavior between the para series and the meta series at ground and excited states.

Fostering the Basic Instinct of Boron in Boron-Beryllium Interactions.

PubMed

Montero-Campillo, M Merced; Alkorta, Ibon; Elguero, José

2018-03-29

A set of complexes L 2 HB···BeX 2 (L = CNH, CO, CS, N 2 , NH 3 , NCCH 3 , PH 3 , PF 3 , PMe 3 , OH 2 ; X = H, F) containing a boron-beryllium bond is described at the M06-2X/6-311+G(3df,2pd)//M062-2X/6-31+G(d) level of theory. In this quite unusual bond, boron acts as a Lewis base and beryllium as a Lewis acid, reaching binding energies up to -283.3 kJ/mol ((H 2 O) 2 HB···BeF 2 ). The stabilization of these complexes is possible thanks to the σ-donor role of the L ligands in the L 2 HB···BeX 2 structures and the powerful acceptor nature of beryllium. According to the topology of the density, these B-Be interactions present positive laplacian values and negative energy densities, covering different degrees of electron sharing. ELF calculations allowed measuring the population in the interboundary B-Be region, which varies between 0.20 and 2.05 electrons upon switching from the weakest ((CS) 2 HB···BeH 2 ) to the strongest complex ((H 2 O) 2 HB···BeF 2 ). These B-Be interactions can be considered as beryllium bonds in most cases.

The influence of metal Mg on micro-morphology and crystallinity of spherical hexagonal boron nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ning, E-mail: zhangning5832@163.com; Liu, Huan; Kan, Hongmin

2015-08-15

Highlights: • The action mechanism of Mg to the synthesis of spherical BN was explored. • The influence of Mg content on the crystallinity of h-BN powders was studied. • Even if not added any template, the spherical h-BN could be prepared. - Abstract: This search used the boric acid and borax as a source of boron, urea as a nitrogen source, Mg as metal catalyst, and thus prepared different micro-morphology and crystallinity hexagonal boron nitride powders under a flowing ammonia atmosphere at a nitriding temperature of 750 °C. The effect of Mg content on the crystallinity and micro-morphology ofmore » hexagonal boron nitride powders was studied, and the Mg action mechanism was explored. Without the added surfactant, the graphitization index (GI) was 6.87, and the diameter of the spherical h-BN was bigger. When the added Mg were 0.1 g, 0.3 g, 0.5 g and 0.7 g, the (GI) decreased to 6.04, 5.67, 4.62 and 4.84, respectively. When the Mg content was higher (0.9 g), GI value increased rapidly, and the crystallinity became bad. When the Mg content was 0.5 g, the dispersion of h-BN powders was at its optimum and refinement apparently, and the crystallinity at its highest.« less

Boron diffusion in bcc-Fe studied by first-principles calculations

NASA Astrophysics Data System (ADS)

Xianglong, Li; Ping, Wu; Ruijie, Yang; Dan, Yan; Sen, Chen; Shiping, Zhang; Ning, Chen

2016-03-01

The diffusion mechanism of boron in bcc-Fe has been studied by first-principles calculations. The diffusion coefficients of the interstitial mechanism, the B-monovacancy complex mechanism, and the B-divacancy complex mechanism have been calculated. The calculated diffusion coefficient of the interstitial mechanism is D0 = 1.05 × 10-7 exp (-0.75 eV/kT) m2 · s-1, while the diffusion coefficients of the B-monovacancy and the B-divacancy complex mechanisms are D1 = 1.22 × 10-6 f1 exp (-2.27 eV/kT) m2 · s-1 and D2 ≈ 8.36 × 10-6 exp (-4.81 eV/kT) m2 · s-1, respectively. The results indicate that the dominant diffusion mechanism in bcc-Fe is the interstitial mechanism through an octahedral interstitial site instead of the complex mechanism. The calculated diffusion coefficient is in accordance with the reported experiment results measured in Fe-3%Si-B alloy (bcc structure). Since the non-equilibrium segregation of boron is based on the diffusion of the complexes as suggested by the theory, our calculation reasonably explains why the non-equilibrium segregation of boron is not observed in bcc-Fe in experiments. Project supported by the National Natural Science Foundation of China (Grant No. 51276016) and the National Basic Research Program of China (Grant No. 2012CB720406).

Silk flame retardant finish by ternary silica sol containing boron and nitrogen

NASA Astrophysics Data System (ADS)

Zhang, Qiang-hua; Chen, Guo-qiang; Xing, Tie-ling

2017-11-01

A ternary flame retardant sol system containing Si, B and N was prepared via sol gel method using tetraethoxysilane (TEOS) as a precursor, boric acid (H3BO3) and urea (CO(NH2)2) as flame retardant additives and then applied to silk fabric flame retardant finish. The FT-IR and SEM results showed that the nitrogen-boron-silica ternary sol was successfully prepared and entrapped onto the surface of silk fibers. The limiting oxygen index (LOI) test indicated that the silk fabric treated with 24% boric acid and 6% urea (relative to the TEOS) doped ternary silica sol system performed excellent flame retardancy with the LOI value of 34.6%. Furthermore, in order to endow silk fabric with durable flame retardancy, the silk fabric was pretreated with 1,2,3,4-butanetetracarboxylic acid (BTCA) before the ternary sol system treatment. The BTCA pretreat ment applied to silk could effectively promote the washing durability of the ternary sol, and the LOI value of the treated sample after 10 times washing could still maintain at 30.8% compared with that of 31.0% before washing. Thermo gravimetric (TG), micro calorimeter combustion (MCC) and smoke density test results demonstrated that the thermal stability, heat release and smoke suppression of the nitrogen-boron-silica ternary system decreased somewhat compared with the boron-silica binary flame retardant system.

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

PubMed

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

2015-06-05

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

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

NASA Astrophysics Data System (ADS)

Yılmaz, S. O.; Karataş, S.

2013-06-01

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO2-Na2O) powders for 873-1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as function of treatment time and temperature in the range of 873-1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000-2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe2B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

High density and taper-free boron doped Si{sub 1−x}Ge{sub x} nanowire via two-step growth process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Periwal, Priyanka; Salem, Bassem; Bassani, Franck

2014-07-01

The authors study Au catalyzed chemical vapor growth of Si{sub 1−x}Ge{sub x} alloyed nanowires in the presence of diborane, serving as a dopant precursor. Our experiments reveal that introduction of diborane has a significant effect on doping and morphology. Boron exposure poisons the Au catalyst surface, suppresses catalyst activity, and causes significantly tapered wires, as a result of conformal growth. The authors develop here a two-step method to obtain high density and taper-free boron doped Si{sub 1−x}Ge{sub x} alloy nanowires. The two-step process consists of: (1) growth of a small undoped Si{sub 1−x}Ge{sub x} section and (2) introduction of diboranemore » to form a boron doped Si{sub 1−x}Ge{sub x} section. The catalyst preparation step remarkably influences wire yield, quality and morphology. The authors show that dopant-ratio influences wire resistivity and morphology. Resistivity for high boron doped Si{sub 1−x}Ge{sub x} nanowire is 6 mΩ-cm. Four probe measurements show that it is possible to dope Si{sub 1−x}Ge{sub x} alloy nanowires with diborane.« less

Electroextraction of boron from boron carbide scrap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Ashish; Anthonysamy, S., E-mail: sas@igcar.gov.in; Ghosh, C.

2013-10-15

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

Functionalizing graphene by embedded boron clusters

NASA Astrophysics Data System (ADS)

Quandt, Alexander; Kunstmann, Jens; Ozdogan, Cem; Fehske, Holger

2010-03-01

We present results from an ab initio study of B7 clusters implanted into graphene [1,2]. Our model system consists of an alternating chain of quasiplanar B7 clusters. We show that graphene easily accepts these alternating B7-C6 chains and that the implanted boron components may dramatically modify the electronic properties. This suggests that our model system might serve as a blueprint for the controlled layout of graphene based nanodevices, where the semiconducting properties are supplemented by parts of the graphene matrix itself, and the basic metallic wiring is provided by alternating chains of implanted boron clusters. [1] A. Quandt, C. "Ozdogan, J. Kunstmann, and H. Fehske, Nanotechnology 19, 335707 (2008). [2] A. Quandt, C. "Ozdogan, J. Kunstmann, and H. Fehske, phys. stat. solidi (b) 245, 2077 (2008).

High-pressure, high-temperature synthesis of superhard boron suboxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hubert, H.; Garvie, L.A.J.; Leinenweber, K.

A multianvil device was used to investigate the formation of B{sub x}O phases produced in the 2 to 10 GPa pressure range with temperatures between 1,000 and 1,800 C. Amorphous and crystalline B and BP were oxidized using B{sub 2}O{sub 3} and CrO{sub 3}. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), the authors were unable to detect graphitic or diamond-structured B{sub 2}O, reported in previous studies. The refractory boride B{sub 6}O, which has the {alpha}-rhombohedral boron structure, is the dominant suboxide in the P and T range of the investigation. PEELS with a transmission electron microscope wasmore » used to characterize the boron oxides.« less

Real-Tme Boron Nitride Erosion Measurements of the HiVHAc Thruster via Cavity Ring-Down Spectroscopy

NASA Technical Reports Server (NTRS)

Lee, Brian C.; Yalin, Azer P.; Gallimore, Alec; Huang, Wensheng; Kamhawi, Hani

2013-01-01

Cavity ring-down spectroscopy was used to make real-time erosion measurements from the NASA High Voltage Hall Accelerator thruster. The optical sensor uses 250 nm light to measure absorption of atomic boron in the plume of an operating Hall thruster. Theerosion rate of the High Voltage Hall Accelerator thruster was measured for discharge voltages ranging from 330 to 600 V and discharge powers ranging from 1 to 3 kW. Boron densities as high as 6.5 x 10(exp 15) per cubic meter were found within the channel. Using a very simple boronvelocity model, approximate volumetric erosion rates between 5.0 x 10(exp -12) and 8.2 x 10(exp -12) cubic meter per second were found.

Determination of the optical band-gap energy of cubic and hexagonal boron nitride using luminescence excitation spectroscopy

NASA Astrophysics Data System (ADS)

Evans, D. A.; McGlynn, A. G.; Towlson, B. M.; Gunn, M.; Jones, D.; Jenkins, T. E.; Winter, R.; Poolton, N. R. J.

2008-02-01

Using synchrotron-based luminescence excitation spectroscopy in the energy range 4-20 eV at 8 K, the indirect Γ-X optical band-gap transition in cubic boron nitride is determined as 6.36 ± 0.03 eV, and the quasi-direct band-gap energy of hexagonal boron nitride is determined as 5.96 ± 0.04 eV. The composition and structure of the materials are self-consistently established by optically detected x-ray absorption spectroscopy, and both x-ray diffraction and Raman measurements on the same samples give independent confirmation of their chemical and structural purity: together, the results are therefore considered as providing definitive measurements of the optical band-gap energies of the two materials.

Organocatalytic, enantioselective synthesis of benzoxaboroles via Wittig/oxa-Michael reaction Cascade of α-formyl boronic acids† †Electronic supplementary information (ESI) available. CCDC 1487136. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc04522g Click here for additional data file. Click here for additional data file.

PubMed Central

Hazra, Gurupada; Maity, Sanjay; Bhowmick, Sudipto

2017-01-01

An unprecedented enantioselective synthesis of 3-substituted benzoxaboroles has been developed. An in situ generated ortho-boronic acid containing chalcone provides the chiral benzoxaboroles via an asymmetric oxa-Michael addition of hydroxyl group attached to the boronic acid triggered by the cinchona alkaloid based chiral amino-squaramide catalysts. In general, good yields with good to excellent enantioselectivities (up to 99%) were obtained. The resulting benzoxaboroles were converted to the corresponding chiral β-hydroxy ketones without affecting the enantioselectivity. PMID:28451370

JAGUAR Procedures for Detonation Behavior of Explosives Containing Boron

NASA Astrophysics Data System (ADS)

Stiel, Leonard; Baker, Ernest; Capellos, Christos

2009-06-01

The JAGUAR product library was expanded to include boron and boron containing products. Relationships of the Murnaghan form for molar volumes and derived properties were implemented in JAGUAR. Available Hugoniot and static volumertic data were analyzed to obtain constants of the Murnaghan relationship for solid boron, boron oxide, boron nitride, boron carbide, and boric acid. Experimental melting points were also utilized with optimization procedures to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX - boron mixtures calculated with these relationships using JAGUAR are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that boron mixtures may exhibit eigenvalue detonation behavior, as observed by aluminized combined effects explosives, with higher detonation velocities than would be achieved by a classical Chapman-Jouguet detonation. Analyses of calorimetric measurements for RDX - boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the energy output obtained from the detonation of the formulation.

Process for microwave sintering boron carbide

DOEpatents

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

1993-10-12

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

Process for microwave sintering boron carbide

DOEpatents

Holcombe, Cressie E.; Morrow, Marvin S.

1993-01-01

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

High Energy Advanced Thermal Storage for Spacecraft Solar Thermal Power and Propulsion Systems

DTIC Science & Technology

2011-10-12

Vol. 108, No. 6, June 1961, pp. 568-572. 38. Storms, E. and Mueller, B., "Phase Relations and Thermodynamic Properties of Transition Metal Borides ...T., and Naka, S., "Formation Process of Tungsten Borides by Solid State Reaction Between Tungsten and Amorphous Boron," Journal of Materials...Molybdenum- Borides ," Journal of Metals, September 1952, pp. 983-988. 41. Ellis, R.C., “Various Preparations of Elemental Boron,” Proceedings of the 1st

Thin Refractory Films on Fused Silica Crucibles

DTIC Science & Technology

1988-07-01

9 4.1.4 Iridium 11 4.1.5 Boron Nitride (BN) 11 4.2 Adherence Testing 13 4.3 Metallography 13 5.0 Conclusions and Recommendations 16 Accession For...Chamber 4 2. Schematic of Crucible Coating Apparatus (SiC, NbN, and TiB 2) 6 3. Schematic of CVD Apparatus for Iridium 7 4. Schematic of Apparatus for...ultrahigh-purity coatings of silicon carbide (SiC), niobium nitride (NbN), titanium diboride (TiB2), iridium , and boron nitride (BN) onto the interior

Collaborative study of the determination of boric acid in caviar by emission spectroscopy.

PubMed

Franco, V; Holak, W

1975-03-01

Caviar samples were spiked at the 0.1 and 0.2% levels and digested with nitric acid in a closed Teflon-lined digestion vessel to prevent volatility losses. The boron was complexed with 2-ethyl-1,3-hexanediol and extracted into methylisobulty ketone. The emission of the boron oxide band was measured in a nitrous oxidehydrogen flame. The mean recoveries at the 0.1 and 0.2% levels for 6 collaborators were 95.7 and 97.1%, respectively.

Precision Measurement of the Boron to Carbon Flux Ratio in Cosmic Rays from 1.9 GV to 2.6 TV with the Alpha Magnetic Spectrometer on the International Space Station.

PubMed

Aguilar, M; Ali Cavasonza, L; Ambrosi, G; Arruda, L; Attig, N; Aupetit, S; Azzarello, P; Bachlechner, A; Barao, F; Barrau, A; Barrin, L; Bartoloni, A; Basara, L; Başeğmez-du Pree, S; Battarbee, M; Battiston, R; Becker, U; Behlmann, M; Beischer, B; Berdugo, J; Bertucci, B; Bindel, K F; Bindi, V; Boella, G; de Boer, W; Bollweg, K; Bonnivard, V; Borgia, B; Boschini, M J; Bourquin, M; Bueno, E F; Burger, J; Cadoux, F; Cai, X D; Capell, M; Caroff, S; Casaus, J; Castellini, G; Cervelli, F; Chae, M J; Chang, Y H; Chen, A I; Chen, G M; Chen, H S; Cheng, L; Chou, H Y; Choumilov, E; Choutko, V; Chung, C H; Clark, C; Clavero, R; Coignet, G; Consolandi, C; Contin, A; Corti, C; Creus, W; Crispoltoni, M; Cui, Z; Dai, Y M; Delgado, C; Della Torre, S; Demakov, O; Demirköz, M B; Derome, L; Di Falco, S; Dimiccoli, F; Díaz, C; von Doetinchem, P; Dong, F; Donnini, F; Duranti, M; D'Urso, D; Egorov, A; Eline, A; Eronen, T; Feng, J; Fiandrini, E; Finch, E; Fisher, P; Formato, V; Galaktionov, Y; Gallucci, G; García, B; García-López, R J; Gargiulo, C; Gast, H; Gebauer, I; Gervasi, M; Ghelfi, A; Giovacchini, F; Goglov, P; Gómez-Coral, D M; Gong, J; Goy, C; Grabski, V; Grandi, D; Graziani, M; Guo, K H; Haino, S; Han, K C; He, Z H; Heil, M; Hoffman, J; Hsieh, T H; Huang, H; Huang, Z C; Huh, C; Incagli, M; Ionica, M; Jang, W Y; Jinchi, H; Kang, S C; Kanishev, K; Kim, G N; Kim, K S; Kirn, Th; Konak, C; Kounina, O; Kounine, A; Koutsenko, V; Krafczyk, M S; La Vacca, G; Laudi, E; Laurenti, G; Lazzizzera, I; Lebedev, A; Lee, H T; Lee, S C; Leluc, C; Li, H S; Li, J Q; Li, J Q; Li, Q; Li, T X; Li, W; Li, Y; Li, Z H; Li, Z Y; Lim, S; Lin, C H; Lipari, P; Lippert, T; Liu, D; Liu, Hu; Lordello, V D; Lu, S Q; Lu, Y S; Luebelsmeyer, K; Luo, F; Luo, J Z; Lv, S S; Machate, F; Majka, R; Mañá, C; Marín, J; Martin, T; Martínez, G; Masi, N; Maurin, D; Menchaca-Rocha, A; Meng, Q; Mikuni, V M; Mo, D C; Morescalchi, L; Mott, P; Nelson, T; Ni, J Q; Nikonov, N; Nozzoli, F; Oliva, A; Orcinha, M; Palmonari, F; Palomares, C; Paniccia, M; Pauluzzi, M; Pensotti, S; Pereira, R; Picot-Clemente, N; Pilo, F; Pizzolotto, C; Plyaskin, V; Pohl, M; Poireau, V; Putze, A; Quadrani, L; Qi, X M; Qin, X; Qu, Z Y; Räihä, T; Rancoita, P G; Rapin, D; Ricol, J S; Rosier-Lees, S; Rozhkov, A; Rozza, D; Sagdeev, R; Sandweiss, J; Saouter, P; Schael, S; Schmidt, S M; Schulz von Dratzig, A; Schwering, G; Seo, E S; Shan, B S; Shi, J Y; Siedenburg, T; Son, D; Song, J W; Sun, W H; Tacconi, M; Tang, X W; Tang, Z C; Tao, L; Tescaro, D; Ting, Samuel C C; Ting, S M; Tomassetti, N; Torsti, J; Türkoğlu, C; Urban, T; Vagelli, V; Valente, E; Vannini, C; Valtonen, E; Vázquez Acosta, M; Vecchi, M; Velasco, M; Vialle, J P; Vitale, V; Vitillo, S; Wang, L Q; Wang, N H; Wang, Q L; Wang, X; Wang, X Q; Wang, Z X; Wei, C C; Weng, Z L; Whitman, K; Wienkenhöver, J; Wu, H; Wu, X; Xia, X; Xiong, R Q; Xu, W; Yan, Q; Yang, J; Yang, M; Yang, Y; Yi, H; Yu, Y J; Yu, Z Q; Zeissler, S; Zhang, C; Zhang, J; Zhang, J H; Zhang, S D; Zhang, S W; Zhang, Z; Zheng, Z M; Zhu, Z Q; Zhuang, H L; Zhukov, V; Zichichi, A; Zimmermann, N; Zuccon, P

2016-12-02

Knowledge of the rigidity dependence of the boron to carbon flux ratio (B/C) is important in understanding the propagation of cosmic rays. The precise measurement of the B/C ratio from 1.9 GV to 2.6 TV, based on 2.3 million boron and 8.3 million carbon nuclei collected by AMS during the first 5 years of operation, is presented. The detailed variation with rigidity of the B/C spectral index is reported for the first time. The B/C ratio does not show any significant structures in contrast to many cosmic ray models that require such structures at high rigidities. Remarkably, above 65 GV, the B/C ratio is well described by a single power law R^{Δ} with index Δ=-0.333±0.014(fit)±0.005(syst), in good agreement with the Kolmogorov theory of turbulence which predicts Δ=-1/3 asymptotically.

U.S. Air Force Installation Restoration Program. Phase 1. Records Search. Air National Guard, Camp Edwards (ARNG), U.S. Air Force and Veteran’s Administration Facilities at Massachusetts Military Reservation, Massachusetts. Appendices: Task 6

DTIC Science & Technology

1986-12-11

MG/L Chmia Oxyge 00340 ARSENIC 01000 002BORON 0102 Total Ov-gale 00640 BARIUM 131005 01007 BORON. 01020 CARDON as C 0 * Diseelvud 0 1 CADMIUM 01025...Goldenrod) U - Utricularia sp. (Bladderwort) B - Scirpus sp. (Bulrush) h6 - Myriophyllum tenellui (Leafless Mil- H2 - Elodea sp. (Waterweed) foil) n1... Dioxide I - -- -- Arsenic C 10 (10 10 410 ug/L Barium 14200 j( 200 (200 (200 ug/L Cadmium !4 10 ( 10 1 10 4 10 ug/L Chromium ( 50 4 50 4 50 50 ugSL

Use of Phenylboronic Acids to Investigate Boron Function in Plants. Possible Role of Boron in Transvacuolar Cytoplasmic Strands and Cell-to-Wall Adhesion

PubMed Central

Bassil, Elias; Hu, Hening; Brown, Patrick H.

2004-01-01

The only defined physiological role of boron in plants is as a cross-linking molecule involving reversible covalent bonds with cis-diols on either side of borate. Boronic acids, which form the same reversible bonds with cis-diols but cannot cross-link two molecules, were used to selectively disrupt boron function in plants. In cultured tobacco (Nicotiana tabacum cv BY-2) cells, addition of boronic acids caused the disruption of cytoplasmic strands and cell-to-cell wall detachment. The effect of the boronic acids could be relieved by the addition of boron-complexing sugars and was proportional to the boronic acid-binding strength of the sugar. Experiments with germinating petunia (Petunia hybrida) pollen and boronate-affinity chromatography showed that boronic acids and boron compete for the same binding sites. The boronic acids appear to specifically disrupt or prevent borate-dependent cross-links important for the structural integrity of the cell, including the organization of transvacuolar cytoplasmic strands. Boron likely plays a structural role in the plant cytoskeleton. We conclude that boronic acids can be used to rapidly and reversibly induce boron deficiency-like responses and therefore are useful tools for investigating boron function in plants. PMID:15466241

Method of fabricating boron containing coatings

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1999-01-01

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

Method of fabricating boron containing coatings

DOEpatents

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

1999-04-27

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

High-Dose Neutron Detector Development Using 10B Coated Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menlove, Howard Olsen; Henzlova, Daniela

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 detectionmore » 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.« less

All-boron fullerene exhibits a strong affinity to inorganic anions

NASA Astrophysics Data System (ADS)

Colherinhas, Guilherme; Fileti, Eudes Eterno; Chaban, Vitaly V.

2017-03-01

Experimentally observed all-boron fullerene, B-80, inspires systematic investigation of its physical chemical properties and search for possible applications. We hereby report density functional theory calculations to characterize interactions of B-80 with the selected imidazolium room-temperature ionic liquids (RTILs), dimethylimidazolium nitrate and dimethylimidazolium hexafluorophosphate. Whereas the imidazolium cation exhibits a rather poor affinity to B-80, the inorganic anions form polar covalent bonds with the boron atom occupying a central position within a B-6 hexagon. Attachment of the RTIL ion pairs leads to a significant alteration of the electronic spectra, charge density distribution, valence and conduction molecular orbitals. The total binding energies keeping the RTIL@B80 complexes together range 200-250 kcal mol-1, being higher than the energies of many interactions in chemistry. The observed phenomenon predicts an excellent solubility of B-80 in the considered RTILs, but may also reveal a poor stability of B-80 in the polar media. Our results motivate further efforts in studying the behavior of the all-boron fullerene in polar environments.

Fluid sources and metallogenesis in the Blackbird Co-Cu-Au-Bi-Y-REE district, Idaho, U.S.A.: Insights from major-element and boron isotopic compositions of tourmaline

USGS Publications Warehouse

Trumbull, Robert B.; Slack, John F.; Krienitz, M.-S.; Belkin, Harvey E.; Wiedenbeck, M.

2011-01-01

Tourmaline is a widespread mineral in the Mesoproterozoic Blackbird Co–Cu–Au–Bi–Y–REE district, Idaho, where it occurs in both mineralized zones and wallrocks. We report here major-element and B-isotope compositions of tourmaline from stratabound sulfide deposits and their metasedimentary wallrocks, from mineralized and barren pipes of tourmaline breccia, from late barren quartz veins, and from Mesoproterozoic granite. The tourmalines are aluminous, intermediate in the schorl–dravite series, with Fe/(Fe + Mg) values of 0.30 to 0.85, and 10 to 50% X-site vacancies. Compositional zoning is prominent only in tourmaline from breccias and quartz veins; crystal rims are enriched in Mg, Ca and Ti, and depleted in Fe and Al relative to cores. The chemical composition of tourmaline does not correlate with the presence or absence of mineralization. The δ11B values fall into two groups. Isotopically light tourmaline (−21.7 to −7.6‰) occurs in unmineralized samples from wallrocks, late quartz veins and Mesoproterozoic granite, whereas heavy tourmaline (−6.9 to +3.2‰) is spatially associated with mineralization (stratabound and breccia-hosted), and is also found in barren breccia. At an inferred temperature of 300°C, boron in the hydrothermal fluid associated with mineralization had δ11B values of −3 to +7‰. The high end of this range indicates a marine source of the boron. A likely scenario involves leaching of boron principally from marine carbonate beds or B-bearing evaporites in Mesoproterozoic strata of the region. The δ11B values of the isotopically light tourmaline in the sulfide deposits are attributed to recrystallization during Cretaceous metamorphism, superimposed on a light boron component derived from footwall siliciclastic sediments (e.g., marine clays) during Mesoproterozoic mineralization, and possibly a minor component of light boron from a magmatic–hydrothermal fluid. The metal association of Bi–Be–Y–REE in the Blackbird ores suggests some magmatic input, but involvement of granite-derived fluids cannot be conclusively established from the present database.

Boron nitride converted carbon fiber

DOEpatents

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.

Atomic layer deposition of boron-containing films using B{sub 2}F{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mane, Anil U., E-mail: amane@anl.gov; Elam, Jeffrey W.; Goldberg, Alexander

2016-01-15

Ultrathin and conformal boron-containing atomic layer deposition (ALD) films could be used as a shallow dopant source for advanced transistor structures in microelectronics manufacturing. With this application in mind, diboron tetrafluoride (B{sub 2}F{sub 4}) was explored as an ALD precursor for the deposition of boron containing films. Density functional theory simulations for nucleation on silicon (100) surfaces indicated better reactivity of B{sub 2}F{sub 4} in comparison to BF{sub 3}. Quartz crystal microbalance experiments exhibited growth using either B{sub 2}F{sub 4}-H{sub 2}O for B{sub 2}O{sub 3} ALD, or B{sub 2}F{sub 4}-disilane (Si{sub 2}H{sub 6}) for B ALD, but in both cases,more » the initial growth per cycle was quite low (≤0.2 Å/cycle) and decreased to near zero growth after 8–30 ALD cycles. However, alternating between B{sub 2}F{sub 4}-H{sub 2}O and trimethyl aluminum (TMA)-H{sub 2}O ALD cycles resulted in sustained growth at ∼0.65 Å/cycle, suggesting that the dense –OH surface termination produced by the TMA-H{sub 2}O combination enhances the uptake of B{sub 2}F{sub 4} precursor. The resultant boron containing films were analyzed for composition by x-ray photoelectron spectroscopy, and capacitance measurements indicated an insulating characteristic. Finally, diffused boron profiles less than 100 Å were obtained after rapid thermal anneal of the boron containing ALD film.« less

Boron doped diamond synthesized from detonation nanodiamond in a C-O-H fluid at high pressure and high temperature

NASA Astrophysics Data System (ADS)

Shakhov, Fedor M.; Abyzov, Andrey M.; Takai, Kazuyuki

2017-12-01

Boron doped diamond (BDD) was synthesized under high pressure and high temperature (HPHT) of 7 GPa, 1230 °C in a short time of 10 s from a powder mixtures of detonation nanodiamond (DND), pentaerythritol C5H8(OH)4 and amorphous boron. SEM, TEM, XRD, XPS, FTIR and Raman spectroscopy indicated that BDD nano- and micro-crystals have formed by consolidation of DND particles (4 nm in size). XRD showed the enlargement of crystallites size to 6-80 nm and the increase in diamond lattice parameter by 0.02-0.07% without appearance of any microstrains. Raman spectroscopy was used to estimate the content of boron atoms embedded in the diamond lattice. It was found that the Raman diamond peak shifts significantly from 1332 cm-1 to 1290 cm-1 without appearance of any non-diamond carbon. The correlation between Raman peak position, its width, and boron content in diamond is proposed. Hydrogenated diamond carbon in significant amount was detected by IR spectroscopy and XPS. Due to the doping with boron content of about 0.1 at%, the electrical conductivity of the diamond achieved approximately 0.2 Ω-1 cm-1. Reaction mechanism of diamond growth (models of recrystallization and oriented attachment) is discussed, including the initial stages of pentaerythritol pyrolysis and thermal desorption of functional groups from the surface of DND particles with the generation of supercritical fluid of low-molecular substances (H2O, CH4, CO, CO2, etc.), as well as byproducts formation (B2O3, B4C).

The Anti-Inflammatory Activity of Boron Derivatives in Rodents

PubMed Central

Hall, Iris H.; Burnham, Bruce S.; Chen, Shang Y.; Sood, Anup; Spielvogel, Bernard F.; Morse, Karen W.

1995-01-01

Acyclic amine-carboxyboranes were effective anti-inflammatory agents in mice at 8 mg/kg x 2. These amine-carboxyboranes were more effective than the standard indomethacin at 8 mg/kg x 2, pentoxifylline at 50 mg/kg x 2, and phenylbutazone at 50 mg/kg x 2. The heterocyclic amine derivatives as well as amine-carbamoylboranes, carboalkoxyboranes, and cyanoboranes were generally less active. However, selected aminomethyl-phosphonate-N-cyanoboranes demonstrated greater than 60% reduction of induced inflammation. The boron compounds were also active in the rat induced edema, chronic arthritis, and pleurisy screens, demonstrating activity similar to the standard indomethacin. The compounds were effecive in reducing local pain and decreased the tail flick reflex to pain. The derivatives which demonstrated good anti-inflammatory activity were effective inhibitors of hydrolytic lysosomal, and proteolytic enzyme activities with IC50 50 values equal to -6M in mouse macrophages, human leukocytes, and Be Sal osteofibrolytic cells. In these same cell lines, the agents blocked prostaglandin cyclooxygenase activity with IC50 values of -6M. In mouse macrophage and human leukocytes, 5′ lipoxygenase activity was also inhibited by the boron derivatives with IC50 values of 10-6M. These IC50 values for inhibition of these enzyme activities are consistent with published values of known anti-inflammatory agents which target these enzymes. PMID:18472741

Ionic-liquid mediated olefin hydroboration and heteroatom insertion reactions, and the development of template routes to non-oxide ceramic nano- and micro-structures

NASA Astrophysics Data System (ADS)

Kusari, Upal

The goal of the work described in this dissertation was two-fold: (1) To use the unique properties of ionic liquids to develop new synthetic routes to boron-containing molecules including substituted decaboranes, ortho-carboranes and chalcogeno-boranes, and (2) to combine newly developed chemical precursors with template routes to fabricate the non-oxide ceramics boron carbide, silicon carbide and boron nitride on the micro- and nano-scales. The first application of ionic liquid and related salt systems to the hydroboration of a variety of olefins with the polyborane cage B10H 14, leading to the syntheses of functionalized decaborane clusters, 6-R-B10H13, was demonstrated. The decaborane olefin-hydroboration reaction was found to proceed with a wide variety of functional olefins, including, alkenyl, halide, phenyl, ether, ester, pinacolborane, ketone and alcohol-containing olefins. These reactions provide a general, simple, one-pot and high-yield alternative route to functional boranes. The functional decaboranes were then converted by another ionic liquid mediated reaction, to its ortho -carborane derivatives 3-R-1,2-Et2C2B 10H9. Experimental and computational studies of the hydroboration mechanism suggest that the ionic liquid induced the formation of the B 10H13- anion which behaved as an electrophile in the olefin-hydroboration reaction. The unique properties of ionic liquids were also found to be useful in mediating the insertion of chalcogen heteroatoms into the borane clusters nido-B10H14, nido-5,6-C2B8H12 and arachno -4-CB8H14 and led to the improved syntheses of the known compounds nido-7-SB10H12, nido-7-SeB10H12, nido-7,9,10-SC 2B8H10, nido-7,9,10-SeC 2B8H10 and arachno-6,9-CSB 8H12, as well as the synthesis of the new 10-vertex selena-monocarbaborane arachno-6,9-CSeB8H12 (˜40% yield). The second part of the thesis demonstrated that newly developed chemical precursors can be used in conjunction with silica bead and diatom frustule templates to generate highly uniform, nanoporous layered materials and 3-D, free-standing nano- and micro-structures of boron carbide, boron nitride and silicon carbide. The retention of structural features on the micron and nanometer length scales, allowed the fabrication of advanced materials with a range of potential applications, as shown by the production of a SiC/BN-microbasket composite using the frustule template-derived boron nitride replicas.

Effect of boron additions on phase formation and magnetic properties of TbCu7-type melt spun SmFe ribbons

NASA Astrophysics Data System (ADS)

Zheng, Chuanjiang; Yu, Dunbo; Li, Kuoshe; Luo, Yang; Jin, Jinling; Lu, Shuo; Li, Hongwei; Mao, Yongjun; Quan, Ningtao

2016-08-01

Melt spun ribbons of a series of SmFe12Bx (x=0.0, 0.5, 0.75, 1.0, 1.25, and 1.5) have been prepared by the melt spinning technique. Sm-Fe-B melt spun ribbons with single phase TbCu7-type structure were prepared from the SmFe12Bx (x=0.5, 0.75, and 1.0) alloys at the surface velocity around 40 m/s. The addition of boron not only inhibits the appearance of soft magnetic phase α-Fe, but also enhances the ability of amorphous formation for melt spun Sm-Fe ribbons. The concentration of boron atoms, however, exceeds the limit of the solubility (x>1.0) of Sm-Fe alloys, which does not impede the appearance of α-Fe but accelerates the formation of metastable phase Sm2Fe23B3 that is unfavorable to their magnetic properties. Moreover, it is found that the addition of boron whose concentration is 0.0≤x≤0.75 can stabilize the metastable TbCu7-type structure because of the increase of the lattice parameter ratio c/a. The magnetic properties of as-annealed SmFe12B1.0 melt spun ribbons with an energy product of 2.19MGOe, a coercivity of 2.36 kOe and a remanence of 4.8 kGs have been achieved. The microstructural characteristics of as-annealed melt spun SmFe12 and SmFe12B1.0 ribbons have been discussed as well. The following sequence of the hyperfine field H(6l)

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

PubMed

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

2016-01-01

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

No evidence that boron influences tree species distributions in lowland tropical forests of Panama.

PubMed

Turner, Benjamin L; Zalamea, Paul-Camilo; Condit, Richard; Winter, Klaus; Wright, S Joseph; Dalling, James W

2017-04-01

It was recently proposed that boron might be the most important nutrient structuring tree species distributions in tropical forests. Here we combine observational and experimental studies to test this hypothesis for lowland tropical forests of Panama. Plant-available boron is uniformly low in tropical forest soils of Panama and is not significantly associated with any of the > 500 species in a regional network of forest dynamics plots. Experimental manipulation of boron supply to seedlings of three tropical tree species revealed no evidence of boron deficiency or toxicity at concentrations likely to occur in tropical forest soils. Foliar boron did not correlate with soil boron along a local scale gradient of boron availability. Fifteen years of boron addition to a tropical forest increased plant-available boron by 70% but did not significantly change tree productivity or boron concentrations in live leaves, wood or leaf litter. The annual input of boron in rainfall accounts for a considerable proportion of the boron in annual litterfall and is similar to the pool of plant-available boron in the soil, and is therefore sufficient to preclude boron deficiency. We conclude that boron does not influence tree species distributions in Panama and presumably elsewhere in the lowland tropics. No claim to original US government works New Phytologist © 2016 New Phytologist Trust.

6. BUILDING 8768, NORTHWEST SIDE AND SOUTHWEST FRONT. Edwards ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. BUILDING 8768, NORTHWEST SIDE AND SOUTHWEST FRONT. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Observation Bunkers for Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

6. DETAIL, WEST SIDE, SOUTH BAY, SHOWING ENTRANCE TO INSTRUMENTATION ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. DETAIL, WEST SIDE, SOUTH BAY, SHOWING ENTRANCE TO INSTRUMENTATION ROOM. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-4, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

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

PubMed

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

2014-04-15

Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center-two-electron (2c-2e) σ bonds on the periphery and delocalized multicenter-two-electron (nc-2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron's electron deficiency and leads to fluxional behavior, which has been observed in B13(+) and B19(-). A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B(-), formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B(-)/C analogy. It is believed that the electronic transmutation concept will be effective and valuable in aiding the design of new boride materials with predictable properties. The study of boron clusters with intermediate properties between those of individual atoms and bulk solids has given rise to a unique opportunity to broaden the frontier of boron chemistry. Understanding boron clusters has spurred experimentalists and theoreticians to find new boron-based nanomaterials, such as boron fullerenes, nanotubes, two-dimensional boron, and new compounds containing boron clusters as building blocks. Here, a brief and timely overview is presented addressing the recent progress made on boron clusters and the approaches used in the authors' laboratories to determine the structure, stability, and chemical bonding of size-selected boron clusters by joint photoelectron spectroscopy and theoretical studies. Specifically, key findings on all-boron hydrocarbon analogues, metal-centered boron wheels, and electronic transmutation in boron clusters are summarized.

Microstructural stability and thermomechanical processing of boron modified beta titanium alloys

NASA Astrophysics Data System (ADS)

Cherukuri, Balakrishna

One of the main objectives during primary processing of titanium alloys is to reduce the prior beta grain size. Producing an ingot with smaller prior beta grain size could potentially eliminate some primary processing steps and thus reduce processing cost. Trace additions of boron have been shown to decrease the as-cast grain size in alpha + beta titanium alloys. The primary focus of this dissertation is to investigate the effect of boron on microstructural stability and thermomechanical processing in beta titanium alloys. Two metastable beta titanium alloys: Ti-15Mo-2.6Nb-3Al-0.2Si (Beta21S) and Ti-5Al-5V-5Mo-3Cr (Ti5553) with 0.1 wt% B and without boron additions were used in this investigation. Significant grain refinement of the as-cast microstructure and precipitation of TiB whiskers along the grain boundaries was observed with boron additions. Beta21S and Beta21S-0.1B alloys were annealed above the beta transus temperature for different times to investigate the effect of boron on grain size stability. The TiB precipitates were very effective in restricting the beta grain boundary mobility by Zener pinning. A model has been developed to predict the maximum grain size as a function of TiB size, orientation, and volume fraction. Good agreement was obtained between model predictions and experimental results. Beta21S alloys were solution treated and aged for different times at several temperatures below the beta transus to study the kinetics of alpha precipitation. Though the TiB phase did not provide any additional nucleation sites for alpha precipitation, the grain refinement obtained by boron additions resulted in accelerated aging. An investigation of the thermomechanical processing behavior showed different deformation mechanisms above the beta transus temperature. The non-boron containing alloys showed a non-uniform and fine recrystallized necklace structure at grain boundaries whereas uniform intragranular recrystallization was observed in boron containing alloys. Micro-voids were observed at the ends of the TiB needles at high temperature, slow strain rates as a result of decohesion at the TiB/matrix interfaces. At low temperatures and faster strain rates micro voids were also formed due to fracture of TiB needles. Finite element analysis on void formation in TiB containing alloys were in agreement with experimental observations. Microhardness and tensile testing of as-cast + forged and aged Beta21S and Ti5553 alloys with and without boron did not show any significant differences in mechanical properties. The primary benefits of boron modified alloys are in as-cast condition.

Thin layer of ordered boron-doped TiO2 nanotubes fabricated in a novel type of electrolyte and characterized by remarkably improved photoactivity

NASA Astrophysics Data System (ADS)

Siuzdak, Katarzyna; Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Karczewski, Jakub; Ryl, Jacek

2015-12-01

This paper reports a novel method of boron doped titania nanotube arrays preparation by electrochemical anodization in electrolyte containing boron precursor - boron trifluoride diethyl etherate (BF3 C4H10O), simultaneously acting as an anodizing agent. A pure, ordered TiO2 nanotubes array, as a reference sample, was also prepared in solution containing a standard etching compound: ammonium fluoride. The doped and pure titania were characterized by scanning electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and by means of electrochemical methods. The B-doping decidedly shifts the absorption edge of TiO2 nanotubes towards the visible light region and significantly inhibits the radiative recombination processes. Despite the fact that the doped sample is characterized by 4.6 lower real surface area when compared to pure titania, it leads to the decomposition of methylene blue in 93%, that is over 2.3 times higher than the degradation efficiency exhibited by the undoped material. The formation rate of hydroxyl radicals (rad OH) upon illumination significantly favours boron doped titania as a photocatalytic material. Moreover, the simple doping of TiO2 nanotubes array results in the enhancement of generated photocurrent from 120 μA/cm2 to 350 μA/cm2 registered for undoped and doped electrode, respectively.

6. COMPRESSOR CONTROL PANELS: AT LEFT, 6,000 P.S.I. PANEL, CIRCA ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. COMPRESSOR CONTROL PANELS: AT LEFT, 6,000 P.S.I. PANEL, CIRCA 1957; AT RIGHT, FACING CAMERA, 10,000 P.S.I. PANEL. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Helium Compression Plant, Test Area 1-115, intersection of Altair & Saturn Boulevards, Boron, Kern County, CA

Calibration of the borated ion chamber at NIST reactor thermal column.

PubMed

Wang, Z; Hertel, N E; Lennox, A

2007-01-01

In boron neutron capture therapy and boron neutron capture enhanced fast neutron therapy, the absorbed dose of tissue due to the boron neutron capture reaction is difficult to measure directly. This dose can be computed from the measured thermal neutron fluence rate and the (10)B concentration at the site of interest. A borated tissue-equivalent (TE) ion chamber can be used to directly measure the boron dose in a phantom under irradiation by a neutron beam. Fermilab has two Exradin 0.5 cm(3) Spokas thimble TE ion chambers, one loaded with boron, available for such measurements. At the Fermilab Neutron Therapy Facility, these ion chambers are generally used with air as the filling gas. Since alpha particles and lithium ions from the (10)B(n,alpha)(7)Li reactions have very short ranges in air, the Bragg-Gray principle may not be satisfied for the borated TE ion chamber. A calibration method is described in this paper for the determination of boron capture dose using paired ion chambers. The two TE ion chambers were calibrated in the thermal column of the National Institute of Standards and Technology (NIST) research reactor. The borated TE ion chamber is loaded with 1,000 ppm of natural boron (184 ppm of (10)B). The NIST thermal column has a cadmium ratio of greater than 400 as determined by gold activation. The thermal neutron fluence rate during the calibration was determined using a NIST fission chamber to an accuracy of 5.1%. The chambers were calibrated at two different thermal neutron fluence rates: 5.11 x 10(6) and 4.46 x 10(7)n cm(-2) s(-1). The non-borated ion chamber reading was used to subtract collected charge not due to boron neutron capture reactions. An optically thick lithium slab was used to attenuate the thermal neutrons from the neutron beam port so the responses of the chambers could be corrected for fast neutrons and gamma rays in the beam. The calibration factor of the borated ion chamber was determined to be 1.83 x 10(9) +/- 5.5% (+/- 1sigma) n cm(-2) per nC at standard temperature and pressure condition.

Direct current sputtering of boron from boron/boron mixtures

DOEpatents

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

1994-12-13

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

Recent developments with boron as a platform for novel drug design.

PubMed

Leśnikowski, Zbigniew J

2016-06-01

After decades of development, the medicinal chemistry of compounds that contain a single boron atom has matured to the present status of having equal rights with other branches of drug discovery, although it remains a relative newcomer. In contrast, the medicinal chemistry of boron clusters is less advanced, but it is expanding and may soon become a productive area of drug discovery. The author reviews the current developments of medicinal chemistry of boron and its applications in drug design. First generation boron drugs that bear a single boron atom and second generation boron drugs that utilize boron clusters as pharmacophores or modulators of bioactive molecules are discussed. The advantages and gaps in our current understanding of boron medicinal chemistry, with a special focus on boron clusters, are highlighted. Boron is not a panacea for every drug discovery problem, but there is a good chance that it will become a useful addition to the medicinal chemistry tool box. The present status of boron resembles the medicinal chemistry status of fluorine three decades ago; indeed, currently, approximately 20% of pharmaceuticals on the market contain fluorine. The fact that novel boron compounds, especially those based on abiotic polyhedral boron hydrides, are currently unfamiliar could be advantageous because organisms may be less prone to developing resistance against boron cluster-based drugs.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.

Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiationmore » has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B–/C analogy. It is believed that the electronic transmutation concept will be effective and valuable in aiding the design of new boride materials with predictable properties. The study of boron clusters with intermediate properties between those of individual atoms and bulk solids has given rise to a unique opportunity to broaden the frontier of boron chemistry. Understanding boron clusters has spurred experimentalists and theoreticians to find new boron-based nanomaterials, such as boron fullerenes, nanotubes, two-dimensional boron, and new compounds containing boron clusters as building blocks. Here, a brief and timely overview is presented addressing the recent progress made on boron clusters and the approaches used in the authors’ laboratories to determine the structure, stability, and chemical bonding of size-selected boron clusters by joint photoelectron spectroscopy and theoretical studies. Specifically, key findings on all-boron hydrocarbon analogues, metal-centered boron wheels, and electronic transmutation in boron clusters are summarized.« less

Formation, stability and crystal structure of mullite-type Al{sub 6−x}B{sub x}O{sub 9}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffmann, K., E-mail: Kristin.Hoffmann@uni-bremen.de; Institut für Anorganische Chemie und Kristallographie, FB02, Leobener Straße/NW2, Universität Bremen, D-28359 Bremen; Hooper, T.J.N.

2016-11-15

Mullite-type Al{sub 6−x}B{sub x}O{sub 9} compounds were studied by means of powder diffraction and spectroscopic methods. The backbones of this structure are chains of edge-connected AlO{sub 6} octahedra crosslinked by AlO- and BO-polyhedra. Rietveld refinements show that the a and b lattice parameters can be well resolved, thus representing an orthorhombic metric. A continuous decrease of the lattice parameters most pronounced in c-direction indicates a solid solution for Al{sub 6−x}B{sub x}O{sub 9} with 1.09≤x≤2. A preference of boron in 3-fold coordination is confirmed by {sup 11}B MAS NMR spectroscopy and Fourier calculations based on neutron diffraction data collected at 4more » K. Distance Least Squares modeling was performed to simulate a local geometry avoiding long B-O distances linking two octahedral chains by planar BO{sub 3} groups yielding split positions for the oxygen atoms and a strong distortion in the octahedral chains. The lattice thermal expansion was calculated using the Grüneisen first-order equation of state Debye-Einstein-Anharmonicity model. - Graphical abstract: Local distortion induced by boron linking the octahedral chains. - Highlights: • Decreasing lattice parameters indicate a solid solution for Al{sub 6−x}B{sub x}O{sub 9} (1.09≤x≤2). • B-atoms induce a local distortion of neighboring AlO{sub 6} octahedra. • A preference of boron in BO{sub 3} coordination is confirmed by {sup 11}B MAS NMR spectroscopy. • An optimized structural model for Al{sub 6−x}B{sub x}O{sub 9} is presented.« less

SU-E-T-132: Assess the Shielding of Secondary Neutrons From Patient Collimator in Proton Therapy Considering Secondary Photons Generated in the Shielding Process with Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamanaka, M; Takashina, M; Kurosu, K

Purpose: In this study we present Monte Carlo based evaluation of the shielding effect for secondary neutrons from patient collimator, and secondary photons emitted in the process of neutron shielding by combination of moderator and boron-10 placed around patient collimator. Methods: The PHITS Monte Carlo Simulation radiation transport code was used to simulate the proton beam (Ep = 64 to 93 MeV) from a proton therapy facility. In this study, moderators (water, polyethylene and paraffin) and boron (pure {sup 10}B) were placed around patient collimator in this order. The rate of moderator and boron thicknesses was changed fixing the totalmore » thickness at 3cm. The secondary neutron and photons doses were evaluated as the ambient dose equivalent per absorbed dose [H*(10)/D]. Results: The secondary neutrons are shielded more effectively by combination moderators and boron. The most effective combination of shielding neutrons is the polyethylene of 2.4 cm thick and the boron of 0.6 cm thick and the maximum reduction rate is 47.3 %. The H*(10)/D of secondary photons in the control case is less than that of neutrons by two orders of magnitude and the maximum increase of secondary photons is 1.0 µSv/Gy with the polyethylene of 2.8 cm thick and the boron of 0.2 cm thick. Conclusion: The combination of moderators and boron is beneficial for shielding secondary neutrons. Both the secondary photons of control and those emitted in the shielding neutrons are very lower than the secondary neutrons and photon has low RBE in comparison with neutron. Therefore the secondary photons can be ignored in the shielding neutrons.This work was supported by JSPS Core-to-Core Program (No.23003). This work was supported by JSPS Core-to-Core Program (No.23003)« less

Efficient Boron-Carbon-Nitrogen Nanotube Formation Via Combined Laser-Gas Flow Levitation

NASA Technical Reports Server (NTRS)

Whitney, R. Roy (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin (Inventor)

2015-01-01

A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula BxCyNz.

Syntheses of super-hard boron-rich solids in the B-C-N-O system

NASA Astrophysics Data System (ADS)

Hubert, Herve Pierre

Alpha-rhombohedral (alpha-rh.) B-rich materials belonging to the B-C-N-O system were prepared using high-pressure, high-temperature techniques. The samples were synthesized using a multianvil device and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and parallel electron energy-loss spectroscopy (PEELS). In the B-O system, the formation of BsbxO materials produced from mixtures of B and Bsb2Osb3 between 1 to 10 GPa and 1000 to 1800sp°C was investigated. Graphitic and diamond-like Bsb2O, reported in previous studies, were not detected. The refractory boron suboxide, nominally Bsb6O, which has the alpha-rh. B structure, is the dominant suboxide in the P and T range of our investigation. High-pressure techniques were used successfully to synthesize boron suboxide of improved purity and crystallinity, and less oxygen-deficient (i.e., closer to the nominal Bsb6O composition) in comparison to room-pressure syntheses. Quantitative analyses indicate compositions of Bsb6Osb{0.95} and Bsb6Osb{0.77} for high-pressure and room-pressure samples, respectively. The first preparation, between 4 to 5.5 GPa, of Bsb6O in which the preferred form of the material is as macroscopic near-perfect regular icosahedra (to 30 mum in diameter) is reported. The Bsb6O icosahedra are similar to the multiply-twinned particles observed in some cubic materials. However, a major difference is that Bsb6O has a rhombohedral structure that closely fits the geometrical requirements for obtaining icosahedral twins. The Bsb6O grains are neither 3D-periodic nor quasicrystalline. Their formation can be described as a Mackay packing of icosahedral Bsb{12} units and provides an alternative to crystal formation by propagation of translational symmetry. Icosahedral twins ranging from 20 nm to 30 mum in diameter, as well as micron-sized euhedral crystals (to 40 mum) were prepared. The structural similarity of compounds with the alpha-rh. B structure is thought to lead to solid solution. In the B-C-O system, intermediate phases were prepared showing evidence of solid solution between Bsb4C and Bsb6O. Boron carbide crystals containing a significant amount of O, typically Bsb6Csb{1.1}Osb{0.33} and Bsb6Csb{1.28}Osb{0.31}, were grown to 20 mum in diameter from mixtures in which B and C were reacted with excess Bsb2Osb3 at 7.5 GPa and 1700sp°C. Cyclic five-fold twins or twins that approximate Bsb6O icosahedra were observed, but the cell dimensions of the B-C-O materials preclude the formation of icosahedral twins. Nanorods with composition near Bsb6C with minor O were grown in a Bsb2Osb3 melt. The mechanism controlling the growth of the nanorods is similar to the solution-liquid-solid (SLS) process. The first conclusive bulk synthesis of a new boron nitride, Bsb6Nsb1-x, was obtained by reacting B and hexagonal BN at 7.5 GPa and 1700sp°C. XRD and PEELS substantiate that this material has a structure related to that of alpha-rh. B and chemical analysis of this compound showed an average composition of Bsb6Nsb{0.92}.

6. NORTH REAR, WEST PART. VIEW TO SOUTHWEST. TEST STAND ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. NORTH REAR, WEST PART. VIEW TO SOUTHWEST. TEST STAND 1-5 AT RIGHT. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Instrumentation & Control Building, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

6. UNDERGROUND FIRING CONTROL ROOM, INTERIOR. Looking southeast to escape ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. UNDERGROUND FIRING CONTROL ROOM, INTERIOR. Looking southeast to escape tunnel. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Firing Control Building, Test Area 1-100, northeast end of Test Area 1-100 Road, Boron, Kern County, CA

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

NASA Technical Reports Server (NTRS)

Chu, T. L.

1975-01-01

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

The Effects of Stoichiometry on the Mechanical Properties of Icosahedral Boron Carbide Under Loading

DTIC Science & Technology

2012-11-19

ranging from 10% to 20% C using glancing incidence x - ray diffraction and similar experimental studies of structure as a function of stoichiometry were...blue) positions. it has been suggested that x - ray diffraction analysis of a series of boron-rich materials indicates a distinct change in the c lattice...Angstroms, angles in degrees, volume in cubic Angstroms). Structure Formula % C a b c α β γ Volume Experiment37 B5.6C 15.2 5.19 5.19 5.19 65.18 65.18

Trinity River Bottom Sediment Reconnaissance Study. Phase I. Plan of Work. Appendices,

DTIC Science & Technology

1976-11-30

chromium , cobalt, copper, mercury, molybdepum, nickel and silver. 2. Summary of Metl od 2.1 Arsenic in the sample is first reduced to the trivalent form...a. Arsenic 1. Selenium B-3 b. Barium m. Silver c. Boron n. Zinc d. Cadmium o. Total phosphate e. Copper p. Chemical oxygen demand f. Chromium (total...78.00 3. Boron 0.72 4. Cadmium 1.20 5. Copper 15.50 6. Chromium 14.20 " 7. Lead 323.00 8. Manganese 301.00 9. Mercury 21.00 10. Nickel 13.30 " 11

Pt-B System Revisited: Pt2B, a New Structure Type of Binary Borides. Ternary WAl12-Type Derivative Borides.

PubMed

Sologub, Oksana; Salamakha, Leonid; Rogl, Peter; Stöger, Berthold; Bauer, Ernst; Bernardi, Johannes; Giester, Gerald; Waas, Monika; Svagera, Robert

2015-11-16

On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (≥65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, β = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature. The crystal structure of "hT-Pt3B" complies with the hitherto reported structure of anti-MoS2 [space group P63/mmc, a = 0.279377(2) nm, c = 1.04895(1) nm, RF = 0.075, RI = 0.090]. The structure of the new "[Formula: see text]T-Pt3B" is still unknown. The formation of previously reported Pt∼4B has not been confirmed from binary samples. Exploration of the Pt-rich section of the Pt-Cu-B system at 600 °C revealed a new ternary compound, Pt12CuB6-y [X-ray single-crystal data: space group Im3̅, a = 0.75790(2) nm, y = 3, RF2 = 0.0129], which exhibits the filled WAl12-type structure accommodating boron in the interstitial trigonal-prismatic site 12e. The isotypic platinum-aluminum-boride was synthesized and studied. The solubility of copper in binary platinum borides has been found to attain ∼7 atom % Cu for Pt2B but to be insignificant for "[Formula: see text]T-Pt3B". The architecture of the new Pt2B structure combines puckered layers of boron-filled and empty [Pt6] octahedra (anti-CaCl2-type fragment) alternating along the x axis with a double layer of boron-semifilled [Pt6] trigonal prisms interbedded with a layer of empty tetrahedra and tetragonal pyramids (B-deficient α-T[Formula: see text]I fragment). Assuming boron vacancies ordering (space group R3), the Pt12CuB6-y structure exhibits serpentine-like columns of edge-connected boron-filled [Pt6] trigonal prisms running infinitely along the z axis and embedding the icosahedrally coordinated Cu atom. Pt2B, (Pt1-yCuy)2B (y = 0.045), and Pt12CuB6-y (y = 3) behave metallically, as revealed by temperature-dependent electrical resistivity measurements.

Structural stability and electronic properties of an octagonal allotrope of two dimensional boron nitride.

PubMed

Takahashi, Lauren; Takahashi, Keisuke

2017-03-27

An octagonal allotrope of two dimensional boron nitride is explored through first principles calculations. Calculations show that two dimensional octagonal boron nitride can be formed with a binding energy comparable to two dimensional hexagonal boron nitride. In addition, two dimensional octagonal boron nitride is found to have a band gap smaller than two dimensional hexagonal boron nitride, suggesting the possibility of semiconductive attributes. Two dimensional octagonal boron nitride also has the ability to layer through physisorption. Defects present within two dimensional octagonal boron nitride also lead toward the introduction of a magnetic moment through the absence of boron atoms. The presence of defects is also found to render both hexagonal and octagonal boron nitrides reactive against hydrogen, where greater reactivity is seen in the presence of nitrogen. Thus, two dimensional octagonal boron nitride is confirmed with potential to tailor properties and reactivity through lattice shape and purposeful introduction of defects.

Tensile and compressive stress-strain behavior of heat treated boron-aluminum

NASA Technical Reports Server (NTRS)

Kennedy, J. M.; Tenney, D. R.; Herakovich, C. T.

1978-01-01

An experimental study was conducted to assess the effects of heat treatment and cyclic mechanical loading on the tensile and compressive stress-strain behavior of six boron-aluminum composites having different laminate orientations and being subjected to different heat treatments. The heat treatments were as-fabricated, T6, and T6N consisting of T6 treatment followed by cryogenic quench in liquid nitrogen prior to testing. All laminates were tested in monotonic and cyclic compression, while the tensile-test data are taken from the literature for comparison purposes. It is shown that the linear elastic range of the T6- and T6N-condition specimens is larger than that of the as-fabricated specimens, and that cyclic loading in tension or compression strain hardens the specimens and extends the linear elastic range. For laminates containing 0-deg plies, the stress-strain behavior upon unloading is found to be nonlinear, whereas the other laminates exhibit a linear behavior upon unloading. Specimens in the T6 and T6N conditions show higher strain hardening than the as-fabricated specimens.

In vivo and in vitro effects of boron and boronated compounds.

PubMed

Benderdour, M; Bui-Van, T; Dicko, A; Belleville, F

1998-03-01

Boron is ubiquitously present in soils and water. Associated with pectin it is essential for vascular plants as a component of cell walls, and it stabilizes cell membranes. It is required for the growth of pollen tubes and is involved in membrane transport, stimulating H(+)-pumping ATPase activity and K+ uptake. However, a high boron concentration in the soils is toxic to plants and some boronated derivatives are used as herbicides. An absolute requirement for boron has not been definitively demonstrated in animals and humans. However, experiments with boron supplementation or deprivation show that boron is involved in calcium and bone metabolism, and its effects are more marked when other nutrients (cholecalciferol, magnesium) are deficient. Boron supplementation increases the serum concentration of 17 beta-estradiol and testosterone but boron excess has toxic effects on reproductive function. Boron may be involved in cerebral function via its effects on the transport across membranes. It affects the synthesis of the extracellular matrix and is beneficial in wound healing. Usual dietary boron consumption in humans is 1-2 mg/day for adults. As boron has been shown to have biological activity, research into the chemistry of boronated compounds has increased. Boronated compounds have been shown to be potent anti-osteoporotic, anti-inflammatory, hypolipemic, anti-coagulant and anti-neoplastic agents both in vitro and in vivo in animals.

Boron Neutron Capture Therapy in the Treatment of Recurrent Laryngeal Cancer.

PubMed

Haapaniemi, Aaro; Kankaanranta, Leena; Saat, Riste; Koivunoro, Hanna; Saarilahti, Kauko; Mäkitie, Antti; Atula, Timo; Joensuu, Heikki

2016-05-01

To investigate the safety and efficacy of boron neutron capture therapy (BNCT) as a larynx-preserving treatment option for patients with recurrent laryngeal cancer. Six patients with locally recurrent squamous cell laryngeal carcinoma and 3 patients with persistent laryngeal cancer after prior treatment were treated with BNCT at the FiR1 facility (Espoo, Finland) in 2006 to 2012. The patients had received prior radiation therapy with or without concomitant chemotherapy to a cumulative median dose of 66 Gy. The median tumor diameter was 2.9 cm (range, 1.4-10.9 cm) before BNCT. Boron neutron capture therapy was offered on a compassionate basis to patients who either refused laryngectomy (n=7) or had an inoperable tumor (n=2). Boronophenylalanine-fructose (400 mg/kg) was used as the boron carrier and was infused over 2 hours intravenously before neutron irradiation. Six patients received BNCT once and 3 twice. The estimated average gross tumor volume dose ranged from 22 to 38 Gy (W) (mean; 29 Gy [W]). Six of the 8 evaluable patients responded to BNCT; 2 achieved complete and 4 partial response. One patient died early and was not evaluable for response. Most common side effects were stomatitis, fatigue, and oral pain. No life-threatening or grade 4 toxicity was observed. The median time to progression within the target volume was 6.6 months, and the median overall survival time 13.3 months after BNCT. One patient with complete response is alive and disease-free with a functioning larynx 60 months after BNCT. Boron neutron capture therapy given after prior external beam radiation therapy is well tolerated. Most patients responded to BNCT, but long-term survival with larynx preservation was infrequent owing to cancer progression. Selected patients with recurrent laryngeal cancer may benefit from BNCT. Copyright © 2016 Elsevier Inc. All rights reserved.

Boron Neutron Capture Therapy in the Treatment of Recurrent Laryngeal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haapaniemi, Aaro, E-mail: aaro.haapaniemi@hus.fi; Kankaanranta, Leena; Saat, Riste

2016-05-01

Purpose: To investigate the safety and efficacy of boron neutron capture therapy (BNCT) as a larynx-preserving treatment option for patients with recurrent laryngeal cancer. Methods and Materials: Six patients with locally recurrent squamous cell laryngeal carcinoma and 3 patients with persistent laryngeal cancer after prior treatment were treated with BNCT at the FiR1 facility (Espoo, Finland) in 2006 to 2012. The patients had received prior radiation therapy with or without concomitant chemotherapy to a cumulative median dose of 66 Gy. The median tumor diameter was 2.9 cm (range, 1.4-10.9 cm) before BNCT. Boron neutron capture therapy was offered on a compassionate basis to patientsmore » who either refused laryngectomy (n=7) or had an inoperable tumor (n=2). Boronophenylalanine-fructose (400 mg/kg) was used as the boron carrier and was infused over 2 hours intravenously before neutron irradiation. Results: Six patients received BNCT once and 3 twice. The estimated average gross tumor volume dose ranged from 22 to 38 Gy (W) (mean; 29 Gy [W]). Six of the 8 evaluable patients responded to BNCT; 2 achieved complete and 4 partial response. One patient died early and was not evaluable for response. Most common side effects were stomatitis, fatigue, and oral pain. No life-threatening or grade 4 toxicity was observed. The median time to progression within the target volume was 6.6 months, and the median overall survival time 13.3 months after BNCT. One patient with complete response is alive and disease-free with a functioning larynx 60 months after BNCT. Conclusions: Boron neutron capture therapy given after prior external beam radiation therapy is well tolerated. Most patients responded to BNCT, but long-term survival with larynx preservation was infrequent owing to cancer progression. Selected patients with recurrent laryngeal cancer may benefit from BNCT.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, H; Yoon, D; Jung, J

Purpose: The purpose of this study is to suggest a tumor monitoring technique using prompt gamma rays emitted during the reaction between an antiproton and a boron particle, and to verify the increase of the therapeutic effectiveness of the antiproton boron fusion therapy using Monte Carlo simulation code. Methods: We acquired the percentage depth dose of the antiproton beam from a water phantom with and without three boron uptake regions (region A, B, and C) using F6 tally of MCNPX. The tomographic image was reconstructed using prompt gamma ray events from the reaction between the antiproton and boron during themore » treatment from 32 projections (reconstruction algorithm: MLEM). For the image reconstruction, we were performed using a 80 × 80 pixel matrix with a pixel size of 5 mm. The energy window was set as a 10 % energy window. Results: The prompt gamma ray peak for imaging was observed at 719 keV in the energy spectrum using the F8 tally fuction (energy deposition tally) of the MCNPX code. The tomographic image shows that the boron uptake regions were successfully identified from the simulation results. In terms of the receiver operating characteristic curve analysis, the area under the curve values were 0.647 (region A), 0.679 (region B), and 0.632 (region C). The SNR values increased as the tumor diameter increased. The CNR indicated the relative signal intensity within different regions. The CNR values also increased as the different of BURs diamter increased. Conclusion: We confirmed the feasibility of tumor monitoring during the antiproton therapy as well as the superior therapeutic effect of the antiproton boron fusion therapy. This result can be beneficial for the development of a more accurate particle therapy.« less

Thermal coatings for titanium-aluminum alloys

NASA Technical Reports Server (NTRS)

Cunnington, George R.; Clark, Ronald K.; Robinson, John C.

1993-01-01

Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

The occurrence and hydrochemistry of fluoride and boron in carbonate aquifer system, central and western Estonia.

PubMed

Karro, Enn; Uppin, Marge

2013-05-01

Silurian-Ordovician (S-O) aquifer system is an important drinking water source of central and western Estonia. The fluoride and boron contents of groundwater in aquifer system vary considerably. The fluoride concentration in 60 collected groundwater samples ranged from 0.1 to 6.1 mg/l with a mean of 1.95 mg/l in the study area. Boron content in groundwater varied from 0.05 mg/l to 2.1 mg/l with a mean value of 0.66 mg/l. Considering the requirements of EU Directive 98/83/EC and the Estonian requirements for drinking water quality, the limit value for fluoride (1.5 mg/l) and for boron (1.0 mg/l) is exceeded in 47 and 28 % of wells, respectively. Groundwater with high fluoride and boron concentrations is found mainly in western Estonia and deeper portion of aquifer system, where groundwater chemical type is HCO3-Cl-Na-Mg-Ca, water is alkaline, and its Ca(2+) content is low. Groundwater of the study area is undersaturated with respect to fluorite and near to equilibrium phase with respect to calcite. The comparison of TDS versus Na/(Na + Ca) and Cl/(Cl + HCO3) points to the dominance of rock weathering as the main process, which promotes the availability of fluoride and boron in the groundwater. The geological sources of B in S-O aquifer system have not been studied so far, but the dissolution of fluorides from carbonate rocks (F = 100-400 mg/kg) and K-bentonites (F = 2,800-4,500 mg/kg) contributes to the formation of F-rich groundwater.

Efficient boron-carbon-nitrogen nanotube formation via combined laser-gas flow levitation

DOEpatents

Whitney, R Roy; Jordan, Kevin; Smith, Michael W

2015-03-24

A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z.

Efficient boron nitride nanotube formation via combined laser-gas flow levitation

DOEpatents

Whitney, R. Roy; Jordan, Kevin; Smith, Michael

2014-03-18

A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z. The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B.sub.xC.sub.yN.sub.z.

Efficient Boron Nitride Nanotube Formation via Combined Laser-Gas Flow Levitation

NASA Technical Reports Server (NTRS)

Whitney, R. Roy (Inventor); Jordan, Kevin (Inventor); Smith, Michael W. (Inventor)

2014-01-01

A process for producing boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z) The process utilizes a combination of laser light and nitrogen gas flow to support a boron ball target during heating of the boron ball target and production of a boron vapor plume which reacts with nitrogen or nitrogen and carbon to produce boron nitride nanotubes and/or boron-carbon-nitrogen nanotubes of the general formula B(sub x)C(sub y)N(sub z).

Direct current sputtering of boron from boron/coron mixtures

DOEpatents

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

1994-01-01

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

Boron stress response and accumulation potential of the extremely tolerant species Puccinellia frigida.

PubMed

Rámila, Consuelo D P; Contreras, Samuel A; Di Domenico, Camila; Molina-Montenegro, Marco A; Vega, Andrea; Handford, Michael; Bonilla, Carlos A; Pizarro, Gonzalo E

2016-11-05

Phytoremediation is a promising technology to tackle boron toxicity, which restricts agricultural activities in many arid and semi-arid areas. Puccinellia frigida is a perennial grass that was reported to hyperaccumulate boron in extremely boron-contaminated sites. To further investigate its potential for phytoremediation, we determined its response to boron stress under controlled conditions (hydroponic culture). Also, as a first step towards understanding the mechanisms underlying its extreme tolerance, we evaluated the presence and expression of genes related with boron tolerance. We found that P. frigida grew normally even at highly toxic boron concentrations in the medium (500mg/L), and within its tissues (>5000mg/kg DW). We postulate that the strategies conferring this extreme tolerance involve both restricting boron accumulation and an internal tolerance mechanism; this is consistent with the identification of putative genes involved in both mechanisms, including the expression of a possible boron efflux transporter. We also found that P. frigida hyperaccumulated boron over a wide range of boron concentrations. We propose that P. frigida could be used for boron phytoremediation strategies in places with different soil characteristics and boron concentrations. Further studies should pave the way for the development of clean and low-cost solutions to boron toxicity problems. Copyright © 2016 Elsevier B.V. All rights reserved.

Atmospheric contribution to boron enrichment in aboveground wheat tissues.

PubMed

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

2017-05-01

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

Identification of a Novel System for Boron Transport: Atr1 Is a Main Boron Exporter in Yeast▿ †

PubMed Central

Kaya, Alaattin; Karakaya, Huseyin C.; Fomenko, Dmitri E.; Gladyshev, Vadim N.; Koc, Ahmet

2009-01-01

Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent protein-tagged Atr1 localized to the cell membrane and vacuole, and ATR1 gene expression was upregulated by boron and several stress conditions. We found that atr1Δ mutants were highly sensitive to boron treatment, whereas cells overexpressing ATR1 were boron resistant. In addition, atr1Δ cells accumulated boron, whereas ATR1-overexpressing cells had low intracellular levels of the element. Furthermore, atr1Δ cells showed stronger boron-dependent phenotypes than mutants deficient in genes previously reported to be implicated in boron metabolism. ATR1 is widely distributed in bacteria, archaea, and lower eukaryotes. Our data suggest that Atr1 functions as a boron efflux pump and is required for boron tolerance. PMID:19414602

6. DETAIL OF NORTH ELEVATION AND FOOTINGS FOR FLAME DEFLECTOR, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. DETAIL OF NORTH ELEVATION AND FOOTINGS FOR FLAME DEFLECTOR, NOW MISSING. Looking east. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

Boron Nitride-supported Sub-nanometer Pd 6 Clusters for Formic Acid Decomposition: A DFT Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schimmenti, Roberto; Cortese, Remedios; Duca, Dario

A periodic, self-consistent planewave DFT study was carried out to explore the potential use of Pd 6 clusters supported on a boron nitride sheet as a catalyst for the selective decomposition of formic acid (HCOOH) to CO 2 and H 2. The competition between formate (HCOO) and carboxyl (COOH) paths on catalytic sites, with different proximities to the support, was studied. Based on energetics alone, the reaction may mainly follow the HCOO route. Slightly lower activation energies were found at the lateral sites of the cluster as compared to top face sites. This is particularly true for the bidentate tomore » monodentate HCOO conversion. Through comparison of results with similar studies on HCOOH decomposition on extended Pd surfaces, it was demonstrated that the existence of undercoordinated sites in the sub-nanometer cluster could play a key role in preferentially stabilizing HCOO over COOH, which is a common CO precursor in this reaction. A hydrogen spillover mechanism was also investigated; migration toward the boron nitride support is not favorable, at least in the early stages of the reaction. However, hydrogen diffusion on the cluster has low barriers compared to those involved in formic acid decomposition.« less

Boron Nitride-supported Sub-nanometer Pd 6 Clusters for Formic Acid Decomposition: A DFT Study

DOE PAGES

Schimmenti, Roberto; Cortese, Remedios; Duca, Dario; ...

2017-04-25

A periodic, self-consistent planewave DFT study was carried out to explore the potential use of Pd 6 clusters supported on a boron nitride sheet as a catalyst for the selective decomposition of formic acid (HCOOH) to CO 2 and H 2. The competition between formate (HCOO) and carboxyl (COOH) paths on catalytic sites, with different proximities to the support, was studied. Based on energetics alone, the reaction may mainly follow the HCOO route. Slightly lower activation energies were found at the lateral sites of the cluster as compared to top face sites. This is particularly true for the bidentate tomore » monodentate HCOO conversion. Through comparison of results with similar studies on HCOOH decomposition on extended Pd surfaces, it was demonstrated that the existence of undercoordinated sites in the sub-nanometer cluster could play a key role in preferentially stabilizing HCOO over COOH, which is a common CO precursor in this reaction. A hydrogen spillover mechanism was also investigated; migration toward the boron nitride support is not favorable, at least in the early stages of the reaction. However, hydrogen diffusion on the cluster has low barriers compared to those involved in formic acid decomposition.« less

White-beam X-ray diffraction and radiography studies on high-boron-containing borosilicate glass at high pressures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ham, Kathryn J.; Vohra, Yogesh K.; Kono, Yoshio

Multi-angle energy-dispersive X-ray diffraction studies and white-beam X-ray radiography were conducted with a cylindrically shaped (1 mm diameter and 0.7 mm high) high-boron-content borosilicate glass sample (17.6% B 2O 3) to a pressure of 13.7 GPa using a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT of the Advanced Photon Source. The measured structure factor S(q) to large q = 19 Å –1 is used to determine information about the internuclear bond distances between various species of atoms within the glass sample. Sample pressure was determined with gold as a pressure standard. The sample height as measured by radiography showed anmore » overall uniaxial compression of 22.5% at 13.7 GPa with 10.6% permanent compaction after decompression to ambient conditions. The reduced pair distribution function G(r) was extracted and Si–O, O–O and Si–Si bond distances were measured as a function of pressure. Lastly, Raman spectroscopy of the pressure recovered sample as compared to starting material showed blue-shift and changes in intensity and widths of Raman bands associated with silicate and four-coordinated boron.« less

White-beam X-ray diffraction and radiography studies on high-boron-containing borosilicate glass at high pressures

DOE PAGES

Ham, Kathryn J.; Vohra, Yogesh K.; Kono, Yoshio; ...

2017-02-06

Multi-angle energy-dispersive X-ray diffraction studies and white-beam X-ray radiography were conducted with a cylindrically shaped (1 mm diameter and 0.7 mm high) high-boron-content borosilicate glass sample (17.6% B 2O 3) to a pressure of 13.7 GPa using a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT of the Advanced Photon Source. The measured structure factor S(q) to large q = 19 Å –1 is used to determine information about the internuclear bond distances between various species of atoms within the glass sample. Sample pressure was determined with gold as a pressure standard. The sample height as measured by radiography showed anmore » overall uniaxial compression of 22.5% at 13.7 GPa with 10.6% permanent compaction after decompression to ambient conditions. The reduced pair distribution function G(r) was extracted and Si–O, O–O and Si–Si bond distances were measured as a function of pressure. Lastly, Raman spectroscopy of the pressure recovered sample as compared to starting material showed blue-shift and changes in intensity and widths of Raman bands associated with silicate and four-coordinated boron.« less

Design, process development, manufacture, test and evaluation of boron-aluminum for space shuttle components

NASA Technical Reports Server (NTRS)

Garrett, R. A.; Niemann, J. T.; Otto, O. R.; Brown, N. M.; Heinrich, R. E.

1973-01-01

A multi phase boron-aluminum design and evaluation program for space shuttle components was conducted, culminating in the fabrication of a 1.22 m (48 inch) x 1.83 m (72 inch) boron-aluminum compression panel capable of distributing a point load of 1555 kN (350,000 lbs) into a uniform running load at a temperature of 589 K (600 F). This panel was of the skin-stringer construction with two intermediate frame supports; seven unidirectional stringers varied in thickness from 5 plies to 52 plies and the skin was contoured to thicknesses ranging from 10 plies to 62 plies. Both the stringers and the skin incorporated Ti-6Al-4V titanium interleaves to increase bearing and in-plane shear strength. The discrete program phases were materials evaluation, design studies, process technology development, fabrication and assembly, and test and evaluation.

Boron monosulfide: Equation of state and pressure-induced phase transition

NASA Astrophysics Data System (ADS)

Cherednichenko, K. A.; Kruglov, I. A.; Oganov, A. R.; Le Godec, Y.; Mezouar, M.; Solozhenko, V. L.

2018-04-01

Quasi-hydrostatic compression of rhombohedral boron monosulfide (r-BS) has been studied up to 50 GPa at room temperature using diamond-anvil cells and angle-dispersive synchrotron X-ray diffraction. A fit of the experimental P-V data to the Vinet equation of state yields the bulk modulus B0 of 42.2(1.4) GPa and its first pressure derivative B0' of 7.6(2) that are in excellent agreement with our ab initio calculations. Formation of a new high-pressure phase of boron monosulfide (hp-BS) has been observed above 35 GPa. According to ab initio evolutionary crystal structure predictions combined with Rietveld refinement of high-pressure X-ray diffraction data, the structure of hp-BS has trigonal symmetry and belongs to the space group P-3m1. As it follows from the electron density of state calculations, the phase transformation is accompanied by an insulator-metal transition.

The behavior of silicon and boron in the surface of corroded nuclear waste glasses : an EFTEM study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buck, E. C.; Smith, K. L.; Blackford, M. G.

1999-11-23

Using electron energy-loss filtered transmission electron microscopy (EFTEM), we have observed the formation of silicon-rich zones on the corroded surface of a West Valley (WV6) glass. This layer is approximately 100-200 nm thick and is directly underneath a precipitated smectite clay layer. Under conventional (C)TEM illumination, this layer is invisible; indeed, more commonly used analytical techniques, such as x-ray energy dispersive spectroscopy (EDS), have failed to describe fully the localized changes in the boron and silicon contents across this region. Similar silicon-rich and boron-depleted zones were not found on corroded Savannah River Laboratory (SRL) borosilicate glasses, including SRL-EA and SRL-51,more » although they possessed similar-looking clay layers. This study demonstrates a new tool for examining the corroded surfaces of materials.« less

Synergic nitrogen source route to inorganic fullerene-like boron nitride with vessel, hollow sphere, onion, and peanut nanostructures.

PubMed

Xu, Fen; Xie, Yi; Zhang, Xu; Zhang, Shuyuan; Liu, Xianming; Tian, Xiaobo

2004-01-26

In this paper we describe the large-scale synthesis of inorganic fullerene-like (IF-like) hexagonal boron nitride with vessel, hollow sphere, peanut, and onion structures by reacting BBr(3) with the synergic nitrogen sources NaNH(2) and NH(4)Cl at 400-450 degrees C for 6-12 h. The composition of products could be confirmed to be pure boron nitride with hexagonal structures by the XRD patterns and FT-IR, XPS, and EDXA spectra. The representative HRTEM images clearly reveal the layerlike features of the products. Here, the peanut-like structure of the IF-like BN is reported for the first time, and added to the list as one kind of new morphology of BN nanomaterials. The similarity in the structure between h-BN and graphite is responsible for the formation of IF-like BN with nanostructures of vessels, hollow spheres, peanuts, and onions.

Alkynyl Moiety for Triggering 1,2‐Metallate Shifts: Enantiospecific sp2–sp3 Coupling of Boronic Esters with p‐Arylacetylenes

PubMed Central

Ganesh, Venkataraman; Odachowski, Marcin

2017-01-01

Abstract The enantiospecific coupling of secondary and tertiary boronic esters to aromatics has been investigated. Using p‐lithiated phenylacetylenes and a range of boronic esters coupling has been achieved by the addition of N‐bromosuccinimide (NBS). The alkyne functionality of the intermediate boronate complex reacts with NBS triggering the 1,2‐migration of the group on boron to carbon giving a dearomatized bromoallene intermediate. At this point elimination and rearomatization occurs with neopentyl boronic esters, giving the coupled products. However, using pinacol boronic esters, the boron moiety migrates to the adjacent carbon resulting in formation of ortho boron‐incorporated coupled products. The synthetic utility of the boron incorporated product has been demonstrated by orthogonal transformation of both the alkyne and boronic ester functionalities. PMID:28618129

Charge transfer induced by MoO3 at boron subphthalocyanine chloride/α-sexithiophene heterojunction interface

NASA Astrophysics Data System (ADS)

Foggiatto, Alexandre L.; Sakurai, Takeaki

2018-03-01

The energy-level alignment of boron subphthalocyanine chloride (SubPc)/α-sexithiophene (6T) grown on MoO3 was investigated using ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS). We demonstrated that the p-doping effect generated by the MoO3 layer can induce charge transfer at the organic-organic heterojunction interface. After the deposition of 6T on MoO3, the fermi level becomes pinned close to the 6T highest occupied molecular orbital (HOMO) level and when SubPc is deposited, owing to its tail states, charge transfer occurs in order to achieve thermodynamic equilibrium. We also demonstrated that the charge transfer can be reduced by annealing the film. We suggested that the reduction of the misalignment on the film induces a reduction in the density of gap states, which controls the charge transfer.

Green and Selective Fluorescent Sensor for Detection of Sn (IV) and Mo (VI) Based on Boron and Nitrogen-Co-Doped Carbon Dots.

PubMed

Tabaraki, Reza; Abdi, Omran; Yousefipour, Sedigheh

2017-03-01

A green and simple microwave-assisted method was used to synthesis water-soluble boron and nitrogen-co-doped carbon dots (B-N-CDs). These B-N-CDs were successfully used for the fluorescent determination of Sn 4+ and Mo 6+ ions. This probe had a fast response time at pH = 4 with high sensitivity and selectivity. Linear correlation between F 0 /F and the concentration was seen in the range of 0.2-18 μM and 0.2-25 μM for Sn 4+ and Mo 6+ , respectively. Under optimum condition, the limit of detection (LOD) for Sn 4+ and Mo 6+ were 150 nM and 132 nM, respectively. The performance of the sensor was evaluated by different real samples such as tap, river and mineral water, canned fish sample and tomato samples.

Boron neutron capture therapy outcomes for advanced or recurrent head and neck cancer.

PubMed

Suzuki, Minoru; Kato, Ituro; Aihara, Teruhito; Hiratsuka, Junichi; Yoshimura, Kenichi; Niimi, Miyuki; Kimura, Yoshihiro; Ariyoshi, Yasunori; Haginomori, Shin-Ichi; Sakurai, Yoshinori; Kinashi, Yuko; Masunaga, Shin-Ichiro; Fukushima, Masanori; Ono, Koji; Maruhashi, Akira

2014-01-01

We retrospectively review outcomes of applying boron neutron capture therapy (BNCT) to unresectable advanced or recurrent head and neck cancers. Patients who were treated with BNCT for either local recurrent or newly diagnosed unresectable head or neck cancers between December 2001 and September 2007 were included. Clinicopathological characteristics and clinical outcomes were retrieved from hospital records. Either a combination of borocaptate sodium and boronophenylalanine (BPA) or BPA alone were used as boron compounds. In all the treatment cases, the dose constraint was set to deliver a dose <10-12 Gy-eq to the skin or oral mucosa. There was a patient cohort of 62, with a median follow-up of 18.7 months (range, 0.7-40.8). A total of 87 BNCT procedures were performed. The overall response rate was 58% within 6 months after BNCT. The median survival time was 10.1 months from the time of BNCT. The 1- and 2-year overall survival (OS) rates were 43.1% and 24.2%, respectively. The major acute Grade 3 or 4 toxicities were hyperamylasemia (38.6%), fatigue (6.5%), mucositis/stomatitis (9.7%) and pain (9.7%), all of which were manageable. Three patients died of treatment-related toxicity. Three patients experienced carotid artery hemorrhage, two of whom had coexistent infection of the carotid artery. This study confirmed the feasibility of our dose-estimation method and that controlled trials are warranted.

Methods of producing continuous boron carbide fibers

DOEpatents

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.

In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 presentmore » results from an investigation of boron uptake in vivo by the synovium.« less

Fragment approach to the electronic structure of τ -boron allotrope

NASA Astrophysics Data System (ADS)

Karmodak, Naiwrit; Jemmis, Eluvathingal D.

2017-04-01

The presence of nonconventional bonding features is an intriguing part of elemental boron. The recent addition of τ boron to the family of three-dimensional boron allotropes is no exception. We provide an understanding of the electronic structure of τ boron using a fragment molecular approach, where the effect of symmetry reduction on skeletal bands of B12 and the B57 fragments are examined qualitatively by analyzing the projected density of states of these fragments. In spite of the structural resemblance to β boron, the reduction of symmetry from a rhombohedral space group to the orthorhombic one destabilizes the bands and reduces the electronic requirements. This suggests the presence of the partially occupied boron sites, as seen for a β boron unit cell, and draws the possibility for the existence of different energetically similar polymorphs. τ boron has a lower binding energy than β boron.

Fabrication of antibody microarrays by light-induced covalent and oriented immobilization.

PubMed

Adak, Avijit K; Li, Ben-Yuan; Huang, Li-De; Lin, Ting-Wei; Chang, Tsung-Che; Hwang, Kuo Chu; Lin, Chun-Cheng

2014-07-09

Antibody microarrays have important applications for the sensitive detection of biologically important target molecules and as biosensors for clinical applications. Microarrays produced by oriented immobilization of antibodies generally have higher antigen-binding capacities than those in which antibodies are immobilized with random orientations. Here, we present a UV photo-cross-linking approach that utilizes boronic acid to achieve oriented immobilization of an antibody on a surface while retaining the antigen-binding activity of the immobilized antibody. A photoactive boronic acid probe was designed and synthesized in which boronic acid provided good affinity and specificity for the recognition of glycan chains on the Fc region of the antibody, enabling covalent tethering to the antibody upon exposure to UV light. Once irradiated with optimal UV exposure (16 mW/cm(2)), significant antibody immobilization on a boronic acid-presenting surface with maximal antigen detection sensitivity in a single step was achieved, thus obviating the necessity of prior antibody modifications. The developed approach is highly modular, as demonstrated by its implementation in sensitive sandwich immunoassays for the protein analytes Ricinus communis agglutinin 120, human prostate-specific antigen, and interleukin-6 with limits of detection of 7.4, 29, and 16 pM, respectively. Furthermore, the present system enabled the detection of multiple analytes in samples without any noticeable cross-reactivities. Antibody coupling via the use of boronic acid and UV light represents a practical, oriented immobilization method with significant implications for the construction of a large array of immunosensors for diagnostic applications.

The Physiological Role of Boron on Health.

PubMed

Khaliq, Haseeb; Juming, Zhong; Ke-Mei, Peng

2018-03-15

Boron is an essential mineral that plays an important role in several biological processes. Boron is required for growth of plants, animals, and humans. There are increasing evidences of this nutrient showing a variety of pleiotropic effects, ranging from anti-inflammatory and antioxidant effects to the modulation of different body systems. In the past few years, the trials showed disease-related polymorphisms of boron in different species, which has drawn attention of scientists to the significance of boron to health. Low boron profile has been related with poor immune function, increased risk of mortality, osteoporosis, and cognitive deterioration. High boron status revealed injury to cell and toxicity in different animals and humans. Some studies have shown some benefits of higher boron status, but findings have been generally mixed, which perhaps accentuates the fact that dietary intake will benefit only if supplemental amount is appropriate. The health benefits of boron are numerous in animals and humans; for instance, it affects the growth at safe intake. Central nervous system shows improvement and immune organs exhibit enhanced immunity with boron supplementation. Hepatic metabolism also shows positive changes in response to dietary boron intake. Furthermore, animals and human fed diets supplemented with boron reveal improved bone density and other benefits including embryonic development, wound healing, and cancer therapy. It has also been reported that boron affects the metabolism of several enzymes and minerals. In the background of these health benefits, low or high boron status is giving cause for concern. Additionally, researches are needed to further elucidate the mechanisms of boron effects, and determine the requirements in different species.

Na{sub 3}[B{sub 20}H{sub 17}NH{sub 3}]: Synthesis and liposomal delivery to murine tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feakes, D.A.; Shelly, K.; Knobler, C.B.

1994-04-12

The polyhedral borane ion [n-B{sub 20}H{sub 18}]{sup 2{minus}} reacts with liquid ammonia in the presence of a suitable base to produce an apical-equatorial (ae) isomer of the [B{sub 20}H{sub 17}NH{sub 3}]{sup 3{minus}} ion, [1-(2{prime}-B{sub 10}H{sub 9})-2-NH{sub 3}B{sub 10}H{sub 8}]{sup 3{minus}}. The structure of this product has been confirmed by {sup 11}B NMR spectroscopy and x-ray crystallography. This species undergoes acid-catalyzed rearrangement to an apical-apical (a{sup 2}) isomer, [1-(1{prime}-B{sub 10}H{sub 9})-2-NH{sub 3}B{sub 10}H{sub 8}]{sup 3{minus}}, whose structure has been determined by {sup 11}B NMR spectroscopy. The sodium salts of both the ae and the a{sup 2} isomers of [B{sub 20}H{sub 17}NH{submore » 3}]{sup 3{minus}} have been encapsulated within small unilamellar liposomes, composed of distearoyl phosphatidyl-choline/cholesterol (1:1), and investigated as boron-delivery agents for boron neutron capture therapy (BNCT) of cancer. The biodistribution of boron was determined after the injection of liposomal suspensions into BALB/c mice bearing EMT6 tumors. Both [B{sub 20}H{sub 17}NH{sub 3}]{sup 3{minus}} isomers exhibited excellent tumor uptake and selectivity at very low injected doses, achieving peak tumor boron concentrations of 30-40 {mu}g of B/g of tissue and tumor/blood boron ratios of {approximately}5. The enhanced retention of the [B{sub 20}H{sub 17}NH{sub 3}]{sup 3{minus}} isomers by EMT6 tumors may be attributed to their facile intracellular oxidation. In another experiment, [ae-B{sub 20}H{sub 17}NH{sub 3}]{sup 3{minus}} was encapsulated in liposomes prepared with 5% PEG-2000-distearoyl phosphatidylethanolamine in the liposome membrane. As expected, these liposomes exhibited a longer circulation lifetime in the biodistribution experiment, resulting in the continued accumulation of boron in the tumor over the entire 48-hr experiment and reaching a maximum of 47 {mu}g of B/g of tumor.« less

Convection enhanced delivery of boronated EGF as a molecular targeting agent for neutron capture therapy of brain tumors

PubMed Central

Yang, Weilian; Wu, Gong; Huo, Tianyao; Tjarks, Werner; Ciesielski, Michael; Fenstermaker, Robert A.; Ross, Brain D.; Wikstrand, Carol J.; Riley, Kent J.; Binns, Peter J.

2010-01-01

In the present study, we have evaluated a boronated dendrimer-epidermal growth factor (BD-EGF) bioconjugate as a molecular targeting agent for boron neutron capture therapy (BNCT) of the human EGFR gene-transfected F98 rat glioma, designated F98EGFR. EGF was chemically linked to a heavily boronated polyamidoamine dendrimer (BD) by means of the heterobifunctional reagent, mMBS. Biodistribution studies were carried out at 6 h and 24 h following intratumoral (i.t.) injection or intracerebral (i.c.) convection enhanced delivery (CED) of 125I-labeled or unlabeled BD-EGF (40 μg 10B/10 μg EGF) to F98 glioma bearing rats. At 24 h. there was 43% more radioactivity in EGFR(+) tumors following CED compared to i.t. injection, and a doubling of the tumor boron concentration (22.3 μg/g vs. 11.7 μg/g). CED of BD-EGF resulted in a 7.2× increase in the volume of distribution within the infused cerebral hemisphere and a 1.9× increase in tumor uptake of BD-EGF compared with i.t. injection. Based on these favorable bio-distribution data, BNCT was carried out at the Massachusetts Institute of Technology nuclear reactor 14 days following i.c. tumor implantation and 24 h. after CED of BD-EGF. These animals had a MST of 54.1 ± 4.7 days compared to 43.0 ± 2.8 days following i.t. injection. Rats that received BD-EGF by CED in combination with i.v. boronophenylalanine (BPA), which has been used in both experimental and clinical studies, had a MST of 86.0 ± 28.1 days compared to 39.8 ± 1.6 days for i.v. BPA alone (P < 0.01), 30.9 ± 1.4 days for irradiated controls and 25.1 ± 1.0 days for untreated controls (overall P < 0.0001). These data have demonstrated that the efficacy of BNCT was significantly increased (P < 0.006), following i.c CED of BD-EGF compared to i.t injection, and that the survival data were equivalent to those previously reported by us using the boronated anti-human-EGF mAb, C225 (cetuximab). PMID:19588228

Enantioselective recognition of mandelic acid by a 3,6-dithiophen-2-yl-9H-carbazole-based chiral fluorescent bisboronic acid sensor.

PubMed

Wu, Yubo; Guo, Huimin; James, Tony D; Zhao, Jianzhang

2011-07-15

We have prepared chiral fluorescent bisboronic acid sensors with 3,6-dithiophen-2-yl-9H-carbazole as the fluorophore. The thiophene moiety was used to extend the π-conjugation framework of the fluorophore in order to red-shift the fluorescence emission and, at the same time, to enhance the novel process where the fluorophore serves as the electron donor of the photoinduced electron transfer process (d-PET) of the boronic acid sensors; i.e., the background fluorescence of the sensor 1 at acidic pH is weaker compared to that at neutral or basic pH, in stark contrast to the typical a-PET boronic acid sensors (where the fluorophore serves as the electron acceptor of the photoinduced electron transfer process). The benefit of the d-PET boronic acid sensors is that the recognition of the hydroxylic acids can be achieved at acidic pH. We found that the thiophene moiety is an efficient π-conjugation linker and electron donor; as a result, the d-PET contrast ratio of the sensors upon variation of the pH is improved 10-fold when compared to the previously reported d-PET sensors without the thiophene moiety. Enantioselective recognition of tartaric acid was achieved at acid pH, and the enantioselectivity (total response K(D)I(F)(D)/K(L)I(F)(L)) is 3.3. The fluorescence enhancement (I(F)(Sample)/I(F)(Blank)) of sensor 1 upon binding with tartaric acid is 3.5-fold at pH 3.0. With the fluorescent bisboronic acid sensor 1, enantioselective recognition of mandelic acid was achieved for the first time. To the best of our knowledge, this is the first time that the mandelic acid has been enantioselectively recognized using a chiral fluorescent boronic acid sensor. Chiral monoboronic acid sensor 2 and bisboronic acid sensor 3 without the thiophene moiety failed to enantioselectively recognize mandelic acid. Our findings with the thiophene-incorporated boronic acid sensors will be important for the design of d-PET fluorescent sensors for the enantioselective recognition of α-hydroxylic acids such as mandelic acid, given that it is currently a challenge to recognize these analytes with boronic acid fluorescent molecular sensors.

Boron nitride composites

DOEpatents

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

2017-02-21

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

The major facilitator superfamily transporter Knq1p modulates boron homeostasis in Kluyveromyces lactis.

PubMed

Svrbicka, Alexandra; Toth Hervay, Nora; Gbelska, Yvetta

2016-03-01

Boron is an essential micronutrient for living cells, yet its excess causes toxicity. To date, the mechanisms of boron toxicity are poorly understood. Recently, the ScATR1 gene has been identified encoding the main boron efflux pump in Saccharomyces cerevisiae. In this study, we analyzed the ScATR1 ortholog in Kluyveromyces lactis--the KNQ1 gene, to understand whether it participates in boron stress tolerance. We found that the KNQ1 gene, encoding a permease belonging to the major facilitator superfamily, is required for K. lactis boron tolerance. Deletion of the KNQ1 gene led to boron sensitivity and its overexpression increased K. lactis boron tolerance. The KNQ1 expression was induced by boron and the intracellular boron concentration was controlled by Knq1p. The KNQ1 promoter contains two putative binding motifs for the AP-1-like transcription factor KlYap1p playing a central role in oxidative stress defense. Our results indicate that the induction of the KNQ1 expression requires the presence of KlYap1p and that Knq1p like its ortholog ScAtr1p in S. cerevisiae functions as a boron efflux pump providing boron resistance in K. lactis.

Anode performance of boron-doped graphites prepared from shot and sponge cokes

NASA Astrophysics Data System (ADS)

Liu, Tao; Luo, Ruiying; Yoon, Seong-Ho; Mochida, Isao

The structures and anode performances of graphitized pristine and boron-doped shot and sponge cokes have been comparatively studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and galvanostatic measurement. The results show that high degree of graphitization can be obtained by the substituted boron atom in the carbon lattice, and boron in the resultant boron-doped graphites mainly exist in the form of boron carbide and boron substituted in the carbon lattice. Both of boron-doped graphites from shot and sponge cokes obtain discharge capacity of 350 mAh g -1 and coulombic efficiency above 90%. Apart from commonly observed discharge plateau for graphite, boron-doped samples in this study also show a small plateau at ca. 0.06 V. This phenomenon can be explained that Li ion stores in the site to be void-like spaces that are produced by "molecular bridging" between the edge sites of graphene layer stack with a release of boron atoms substituted at the edge of graphene layer. The effect of the amount of boron dopant and graphitization temperature on the anode performance of boron-doped graphite are also investigated in this paper.

First Evidence on the Role of Heavy Ion Irradiation of Meteorites and Formamide in the Origin of Biomolecules

NASA Astrophysics Data System (ADS)

Saladino, Raffaele; Carota, Eleonora; Botta, Giorgia; Kapralov, Michail; Timoshenko, Gennady N.; Rozanov, Alexei; Krasavin, Eugene; Di Mauro, Ernesto

2016-11-01

Formamide (NH2CHO) has been irradiated in condensed phase at 273 K by 11B-boron beams in the presence of powdered meteorites of the chondrite and stony-iron types. Relative to the controls (no radiation or no catalysis), a variegate panel of compounds was observed, including purine and pyrimidine nucleobases (uracil, cytosine, adenine, and guanine), nucleobase analogues, heterocycles, and carboxylic acids involved in metabolic pathways. The presence of amino imidazole carbonitrile (AICN), 4,6-diamino purine (4,6-DAP) and 2,4-diamino pyrimidine (2,4-DAPy) among the observed products suggests the occurrence of an unified mechanism based on the generation of radical cyanide species (•CN). These observations contribute to outline plausible prebiotic scenarios involving 11B-boron as energy source.

Method of manufacture of atomically thin boron nitride

DOEpatents

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.

Thermodynamics of Boron Removal from Silicon Using CaO-MgO-Al2O3-SiO2 Slags

NASA Astrophysics Data System (ADS)

Jakobsson, Lars Klemet; Tangstad, Merete

2018-04-01

Slag refining is one of few metallurgical methods for removal of boron from silicon. It is important to know the thermodynamic properties of boron in slags to understand the refining process. The relation of the distribution coefficient of boron to the activity of silica, partial pressure of oxygen, and capacity of slags for boron oxide was investigated. The link between these parameters explains why the distribution coefficient of boron does not change much with changing slag composition. In addition, the thermodynamic properties of dilute boron oxide in CaO-MgO-Al2O3-SiO2 slags was determined. The ratio of the activity coefficient of boron oxide and silica was found to be the most important parameter for understanding changes in the distribution coefficient of boron for different slags. Finally, the relation between the activity coefficient of boron oxide and slag structure was investigated. It was found that the structure can explain how the distribution coefficient of boron changes depending on slag composition.

Boron removal from aqueous solution by direct contact membrane distillation.

PubMed

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

2010-05-15

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

Effects on environment and agriculture of geothermal wastewater and boron pollution in great Menderes basin.

PubMed

Koç, Cengiz

2007-02-01

Boron toxicity is an important disorder that can be limit plant growth on soils of arid and semi arid environments through the world. High concentrations of Boron may occur naturally in the soil or in groundwater, or be added to the soil from mining, fertilizers, or irrigation water. Off all the potential resources, irrigation water is the most important contributor to high levels of soil boron, boron is often found in high concentrations in association with saline soil and saline well water. Although of considerable agronomic importance, our understanding of Boron toxicity is rather fragment and limited. In this study, Boron content of Great Menderes River and Basin was researched. Great Menderes Basin is one of the consequence basins having agricultural potential, aspect of water and soil resources in Turkey. Great Menderes River, water resource of the basin was to be polluted by geothermal wastewater and thermal springs including Boron element. Great Menderes Basin has abundant geothermal water resources which contain high amounts of Boron and these ground water are brought to surface and used for various purposes such as power generation, heating or thermal spring and than discharged to Great Menderes River. In order to prevent Boron pollution and hence unproductively in soils, it is necessary not to discharged water with Boron to irrigation water. According to results, it was obtained that Boron content of River was as high in particular Upper Basin where there was a ground thermal water reservoir. Boron has been accumulated more than plant requirement in this area irrigated by this water. Boron content of River was relatively low in rainy months and irrigation season while it was high in dry season. Boron concentration in the River was to decrease from upstream to downstream. If it is no taken measure presently, about 130,000 ha irrigation areas which was constructed irrigation scheme in the Great Menderes basin will expose the Boron pollution and salinity. Even though Boron concentration of river water is under 0.5 ppm limit value, Boron element will store in basin soils, decrease in crop yields, and occur problematic soils in basin.

Face-capping μ3-BO in B6(BO)7-: boron oxide analogue of B6H7- with rhombic 4c-2e bonds.

PubMed

Guo, Jin-Chang; Lu, Hai-Gang; Zhai, Hua-Jin; Li, Si-Dian

2013-11-14

Using the first-principle approaches, we predict a B6(BO)7(-) cluster with a face-capping μ(3)-BO, which is the boron oxide analogue of closo-B6H7(-) with a face-capping μ(3)-H. Detailed topological analysis of electron density clearly reveals the existence of three rhombic 4c-2e bonds around the B/H apex in both C3v B6(BO)7(-) and C3v B6H7(-), which possesses similar electron densities at their bond and ring critical points. The adaptive natural density partitioning (AdNDP) analysis provides a direct and visual picture of the B-B-B-B/H 4c-2e bonds for the first time. Adiabatic and vertical electron detachment energies of the concerned monoanions are calculated to facilitate their future photoelectron spectroscopy measurements and characterizations. The presence of the B6(BO)7(-) and B6H7(-) clusters extends the BO/H isolobal analogy to the whole μ(n)-BO/H series (n = 1, 2, and 3) and enriches the chemistry of boronyl.

Boron exposure through drinking water during pregnancy and birth size.

PubMed

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

2016-10-01

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

Mathematical modeling and experimental validation of the spatial distribution of boron in the root of Arabidopsis thaliana identify high boron accumulation in the tip and predict a distinct root tip uptake function.

PubMed

Shimotohno, Akie; Sotta, Naoyuki; Sato, Takafumi; De Ruvo, Micol; Marée, Athanasius F M; Grieneisen, Verônica A; Fujiwara, Toru

2015-04-01

Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the root. A computational model of the root is created at the cellular level, describing the boron transporters as observed experimentally. Boron is allowed to diffuse into roots, in cells and cell walls, and to be transported over plasma membranes, reflecting the properties of the different transporters. The model predicts that a region around the quiescent center has a higher concentration of soluble boron than other portions. To evaluate this prediction experimentally, we determined the boron distribution in roots using laser ablation-inductivity coupled plasma-mass spectrometry. The analysis indicated that the boron concentration is highest near the tip and is lower in the more proximal region of the meristem zone, similar to the pattern of soluble boron distribution predicted by the model. Our model also predicts that upward boron flux does not continuously increase from the root tip toward the mature region, indicating that boron taken up in the root tip is not efficiently transported to shoots. This suggests that root tip-absorbed boron is probably used for local root growth, and that instead it is the more mature root regions which have a greater role in transporting boron toward the shoots. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

Mathematical Modeling and Experimental Validation of the Spatial Distribution of Boron in the Root of Arabidopsis thaliana Identify High Boron Accumulation in the Tip and Predict a Distinct Root Tip Uptake Function

PubMed Central

Shimotohno, Akie; Sotta, Naoyuki; Sato, Takafumi; De Ruvo, Micol; Marée, Athanasius F.M.; Grieneisen, Verônica A.; Fujiwara, Toru

2015-01-01

Boron, an essential micronutrient, is transported in roots of Arabidopsis thaliana mainly by two different types of transporters, BORs and NIPs (nodulin26-like intrinsic proteins). Both are plasma membrane localized, but have distinct transport properties and patterns of cell type-specific accumulation with different polar localizations, which are likely to affect boron distribution. Here, we used mathematical modeling and an experimental determination to address boron distributions in the root. A computational model of the root is created at the cellular level, describing the boron transporters as observed experimentally. Boron is allowed to diffuse into roots, in cells and cell walls, and to be transported over plasma membranes, reflecting the properties of the different transporters. The model predicts that a region around the quiescent center has a higher concentration of soluble boron than other portions. To evaluate this prediction experimentally, we determined the boron distribution in roots using laser ablation-inductivity coupled plasma-mass spectrometry. The analysis indicated that the boron concentration is highest near the tip and is lower in the more proximal region of the meristem zone, similar to the pattern of soluble boron distribution predicted by the model. Our model also predicts that upward boron flux does not continuously increase from the root tip toward the mature region, indicating that boron taken up in the root tip is not efficiently transported to shoots. This suggests that root tip-absorbed boron is probably used for local root growth, and that instead it is the more mature root regions which have a greater role in transporting boron toward the shoots. PMID:25670713

Fabrication of boron sputter targets

DOEpatents

Makowiecki, Daniel M.; McKernan, Mark A.

1995-01-01

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

Structure prediction of boron-doped graphene by machine learning

NASA Astrophysics Data System (ADS)

M. Dieb, Thaer; Hou, Zhufeng; Tsuda, Koji

2018-06-01

Heteroatom doping has endowed graphene with manifold aspects of material properties and boosted its applications. The atomic structure determination of doped graphene is vital to understand its material properties. Motivated by the recently synthesized boron-doped graphene with relatively high concentration, here we employ machine learning methods to search the most stable structures of doped boron atoms in graphene, in conjunction with the atomistic simulations. From the determined stable structures, we find that in the free-standing pristine graphene, the doped boron atoms energetically prefer to substitute for the carbon atoms at different sublattice sites and that the para configuration of boron-boron pair is dominant in the cases of high boron concentrations. The boron doping can increase the work function of graphene by 0.7 eV for a boron content higher than 3.1%.

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

PubMed

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

2015-10-01

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

Atomistic modeling of BN nanofillers for mechanical and thermal properties: a review.

PubMed

Kumar, Rajesh; Parashar, Avinash

2016-01-07

Due to their exceptional mechanical properties, thermal conductivity and a wide band gap (5-6 eV), boron nitride nanotubes and nanosheets have promising applications in the field of engineering and biomedical science. Accurate modeling of failure or fracture in a nanomaterial inherently involves coupling of atomic domains of cracks and voids as well as a deformation mechanism originating from grain boundaries. This review highlights the recent progress made in the atomistic modeling of boron nitride nanofillers. Continuous improvements in computational power have made it possible to study the structural properties of these nanofillers at the atomistic scale.

Carbon or boron modified titanium silicide

DOEpatents

Thom, A.J.; Akinc, M.

1998-07-14

A titanium silicide material based on Ti{sub 5}Si{sub 3} intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000 C. Boron is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end. 3 figs.

Carbon or boron modified titanium silicide

DOEpatents

Thom, A.J.; Akinc, M.

1997-12-02

A titanium silicide material based on Ti{sub 5}Si{sub 3} intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000 C. Boron is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end. 3 figs.

Carbon or boron modified titanium silicide

DOEpatents

Thom, Andrew J.; Akinc, Mufit

1996-12-03

A titanium silicide material based on Ti.sub.5 Si.sub.3 intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000.degree. C. Boron is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end.

Carbon or boron modified titanium silicide

DOEpatents

Thom, Andrew J.; Akinc, Mufit

1997-12-02

A titanium silicide material based on Ti.sub.5 Si.sub.3 intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000.degree. C. Boron is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end.

Carbon or boron modified titanium silicide

DOEpatents

Thom, A.J.; Akinc, M.

1996-12-03

A titanium silicide material based on Ti{sub 5}Si{sub 3} intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000 C. Boron is added to a Ti{sub 5}Si{sub 3} base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end. 3 figs.

Carbon or boron modified titanium silicide

DOEpatents

Thom, Andrew J.; Akinc, Mufit

1998-07-14

A titanium silicide material based on Ti.sub.5 Si.sub.3 intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000.degree. C. Boron is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagunova, I.A.

A characteristic feature of the products of mud-volcano activity in the Kerch-Taman region is their high boron content. Distribution of boron in waters of mud volcanoes is characterized by restriction of anomalously high concentrations of boron to mud volcanoes actively operating at the present time in general, and to the most active period of operation of the individual volcano; there is a direct correlation between boron and the hydrocarbonate ion (r/sub B//HCO/sub 3// = 0.5), and between boron and carbon dioxide from the mud-volcano gases (r/sub B//CO/sub 2// = 0.4). The correlation is lacking between boron and mineralization, and betweenmore » boron and chlorine, the correlation is close to inverse. A spatial connection between areas of development of mud volcanism and belts of boron mineralization has been established. Anomalously high boron concentrations in the products of mud volcanism in the Kerch-Taman region are part of the overall increased boron capacity of the Crimea and the Caucasus, which has been controlled by recent magmatic activity.« less

METHOD OF COATING SURFACES WITH BORON

DOEpatents

Martin, G.R.

1949-10-11

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

Boron Dissolved and Particulate Atmospheric Inputs to a Forest Ecosystem (Northeastern France).

PubMed

Roux, Philippe; Turpault, Marie-Pierre; Kirchen, Gil; Redon, Paul-Olivier; Lemarchand, Damien

2017-12-19

Boron concentrations and isotopic compositions of atmospheric dust and dissolved depositions were monitored over a two-year period (2012-2013) in the forest ecosystem of Montiers (Northeastern France). This time series allows the determination of the boron atmospheric inputs to this forest ecosystem and contributes to refine our understanding of the sources and processes that control the boron atmospheric cycle. Mean annual dust and dissolved boron atmospheric depositions are comparable in size (13 g·ha -1 ·yr -1 and 16 g·ha -1 ·yr -1 , respectively), which however show significant intra- and interannual variations. Boron isotopes in dust differ from dissolved inputs, with an annual mean value of +1 ‰ and +18 ‰ for, respectively. The notable high boron contents (190-390 μg·g -1 ) of the dust samples are interpreted as resulting from localized spreading of boron-rich fertilizers, thus indicating a significant local impact of regional agricultural activities. Boron isotopes in dissolved depositions show a clear seasonal trend. The absence of correlation with marine cyclic solutes contradicts a control of atmospheric boron by dissolution of seasalts. Instead, the boron data from this study are consistent with a Rayleigh-like evolution of the atmospheric gaseous boron reservoir with possible but limited anthropogenic and/or biogenic contributions.

Insights into the Mechanisms Underlying Boron Homeostasis in Plants

PubMed Central

Yoshinari, Akira; Takano, Junpei

2017-01-01

Boron is an essential element for plants but is toxic in excess. Therefore, plants must adapt to both limiting and excess boron conditions for normal growth. Boron transport in plants is primarily based on three transport mechanisms across the plasma membrane: passive diffusion of boric acid, facilitated diffusion of boric acid via channels, and export of borate anion via transporters. Under boron -limiting conditions, boric acid channels and borate exporters function in the uptake and translocation of boron to support growth of various plant species. In Arabidopsis thaliana, NIP5;1 and BOR1 are located in the plasma membrane and polarized toward soil and stele, respectively, in various root cells, for efficient transport of boron from the soil to the stele. Importantly, sufficient levels of boron induce downregulation of NIP5;1 and BOR1 through mRNA degradation and proteolysis through endocytosis, respectively. In addition, borate exporters, such as Arabidopsis BOR4 and barley Bot1, function in boron exclusion from tissues and cells under conditions of excess boron. Thus, plants actively regulate intracellular localization and abundance of transport proteins to maintain boron homeostasis. In this review, the physiological roles and regulatory mechanisms of intracellular localization and abundance of boron transport proteins are discussed. PMID:29204148

Boron sorption from aqueous solution by hydrotalcite and its preliminary application in geothermal water deboronation.

PubMed

Guo, Qinghai; Zhang, Yin; Cao, Yaowu; Wang, Yanxin; Yan, Weide

2013-11-01

Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing boron as a major undesirable element. The kinetics process of boron sorption by uncalcined hydrotalcite is controlled by the diffusion of boron from bulk solution to sorbent-solution boundary film and its exchange with interlayer chloride of hydrotalcite, whereas the removal rate of boron by calcined hydrotalcite rests with the restoration process of its layered structure. The results of isotherm sorption experiments reveal that calcined hydrotalcite generally has much stronger ability to lower solution boron concentration than uncalcined hydrotalcite. The combination of adsorption of boron on the residue of MgO-Al2O3 solid solution and intercalation of boron into the reconstructed hydrotalcite structure due to "structural memory effect" is the basic mechanism based on which the greater boron removal by calcined hydrotalcite was achieved. As 15 geothermal water samples were used to test the deboronation ability of calcined hydrotalcite at 65 °C, much lower boron removal efficiencies were observed. The competitive sorption of the other anions in geothermal water, such as HCO3-, SO4(2-), and F-, is the reason why calcined hydrotalcite could not remove boron from geothermal water as effectively as from pure boron solution. However, boron removal percents ranging from 89.3 to 99.0% could be obtained if 50 times of sorbent were added to the geothermal water samples. Calcined hydrotalcite is a good candidate for deboronation of geothermal water.

Synergistic methods for the production of high-strength and low-cost boron carbide

NASA Astrophysics Data System (ADS)

Wiley, Charles Schenck

2011-12-01

Boron carbide (B4C) is a non-oxide ceramic in the same class of nonmetallic hard materials as silicon carbide and diamond. The high hardness, high elastic modulus and low density of B4C make it a nearly ideal material for personnel and vehicular armor. B4C plates formed via hot-pressing are currently issued to U.S. soldiers and have exhibited excellent performance; however, hot-pressed articles contain inherent processing defects and are limited to simple geometries such as low-curvature plates. Recent advances in the pressureless sintering of B4C have produced theoretically-dense and complex-shape articles that also exhibit superior ballistic performance. However, the cost of this material is currently high due to the powder shape, size, and size distribution that are required, which limits the economic feasibility of producing such a product. Additionally, the low fracture toughness of pure boron carbide may have resulted in historically lower transition velocities (the projectile velocity range at which armor begins to fail) than competing silicon carbide ceramics in high-velocity long-rod tungsten penetrator tests. Lower fracture toughness also limits multi-hit protection capability. Consequently, these requirements motivated research into methods for improving the densification and fracture toughness of inexpensive boron carbide composites that could result in the development of a superior armor material that would also be cost-competitive with other high-performance ceramics. The primary objective of this research was to study the effect of titanium and carbon additives on the sintering and mechanical properties of inexpensive B4C powders. The boron carbide powder examined in this study was a sub-micron (0.6 mum median particle size) boron carbide powder produced by H.C. Starck GmbH via a jet milling process. A carbon source in the form of phenolic resin, and titanium additives in the form of 32 nm and 0.9 mum TiO2 powders were selected. Parametric studies of sintering behavior were performed via high-temperature dilatometry in order to measure the in-situ sample contraction and thereby measure the influence of the additives and their amounts on the overall densification rate. Additionally, broad composition and sintering/post-HIPing studies followed by characterization and mechanical testing elucidated the effects of these additives on sample densification, microstructure de- velopment, and mechanical properties such as Vickers hardness and microindentation fracture toughness. Based upon this research, a process has been developed for the sintering of boron carbide that yielded end products with high relative densities (i.e., 100%, or theoretical density), microstructures with a fine (˜2-3 mum) grain size, and high Vickers microindentation hardness values. In addition to possessing these improved physical properties, the costs of producing this material were substantially lower (by a factor of 5 or more) than recently patented work on the pressureless sintering and post-HIPing of phase-pure boron carbide powder. This recently patented work developed out of our laboratory utilized an optimized powder distribution and yielded samples with high relative densities and high hardness values. The current work employed the use of titanium and carbon additives in specific ratios to activate the sintering of boron carbide powder possessing an approximately mono-modal particle size distribution. Upon heating to high temperatures, these additives produced fine-scale TiB2 and graphite inclusions that served to hinder grain growth and substantially improve overall sintered and post-HIPed densities when added in sufficient concentrations. The fine boron carbide grain size manifested as a result of these second phase inclusions caused a substantial increase in hardness; the highest hardness specimen yielded a hardness value (2884.5 kg/mm2) approaching that of phase-pure and theoretically-dense boron carbide (2939 kg/mm2). Additionally, the same high-hardness composition exhibited a noticeably higher fracture toughness (3.04 MPa˙m1/2) compared to phase-pure boron carbide (2.42 MPa˙m1/2), representing a 25.6% improvement. A potential consequence of this study would be the development of a superior armor material that is sufficiently affordable, allowing it to be incorporated into the general soldier's armor chassis.

Experimental and Theoretical Investigations of Doubly-excited Sextet States in

NASA Astrophysics Data System (ADS)

Lin, Bin; Berry, H. Gordon; Livingston, A. Eugene; Garnir, Henri-Pierre; Bastin, Thierry; Désesquelles, J.

2002-05-01

The energies and wave functions of the highly doubly-excited sextet states of boron-like O IV, F V and Ne VI are calculated with the Multi-Configuration Hartree-Fock (MCHF) plus the hydrogen-like QED effects and higher-order corrections method. The highly doubly-excited sextet states of boron-like O IV, F V and Ne VI are well above several ionization levels and metastable, and possible candidates for XUV- and soft x-ray laser and energy storage. Three doubly-excited sextet configurations (1s2s2p3 6So, 1s2s2p23s 6P and 1s2p33s 6So) are studied. The wavelengths of electric dipole transitions from the inner-shell excited terms 1s2s2p23s 6P-1s2p33s 6So are investigated by the beam-foil spectroscopy in the XUV spectral region. The predicted transition wavelengths agree with the experiment to 0.08Å. The higher-order corrections and fine structures are found to be critically important in these comparisons.

Development of magnetic resonance technology for noninvasive boron quantification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradshaw, K.M.

1990-11-01

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

Special features of the technology of boronizing steel in a calcium chloride melt

NASA Astrophysics Data System (ADS)

Chernov, Ya. B.; Anfinogenov, A. I.; Veselov, I. N.

1999-12-01

A technology for hardening machine parts and tools by boronizing in molten calcium chloride with amorphous-boron powder in electrode salt baths has been developed with the aim of creating a closed cycle of utilizing the raw materials and the washing water. A process of boronizing that includes quenching and tempering of the boronized articles is described. The quenching medium is an ecologically safe and readily available aqueous solution of calcium chloride. The process envisages return of the melt components to the boronizing bath. Boronizing by the suggested method was tested for different classes of steel, namely, structural and tool steels for cold and hot deformation. The wear resistance of the boronized steels was studied.

Fabrication of boron sputter targets

DOEpatents

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

1995-02-28

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

Process of Making Boron-Fiber Reinforced Composite Tape

NASA Technical Reports Server (NTRS)

Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor); Johnston, Norman J. (Inventor); Marchello, Joseph M. (Inventor)

2002-01-01

The invention is an apparatus and method for producing a hybrid boron reinforced polymer matrix composition from powder pre-impregnated fiber tow bundles and a linear array of boron fibers. The boron fibers are applied onto the powder pre-impregnated fiber tow bundles and then are processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the powder pre-impregnated fiber tow bundles with the boron fibers become a hybrid boron reinforced polymer matrix composite tape. A driving mechanism pulls the powder pre-impregnated fiber tow bundles with boron fibers through the processing line of the apparatus and a take-up spool collects the formed hybrid boron-fiber reinforced polymer matrix composite tape.

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

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Boron removal in radioactive liquid waste by forward osmosis membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doo Seong Hwang; Hei Min Choi; Kune Woo Lee

2013-07-01

This study investigated the treatment of boric acid contained in liquid radioactive waste using a forward osmosis membrane. The boron permeation through the membrane depends on the type of membrane, membrane orientation, pH of the feed solution, salt and boron concentration in the feed solution, and osmotic pressure of the draw solution. The boron flux begins to decline from pH 7 and increases with an increase of the osmotic driving force. The boron flux decreases slightly with the salt concentration, but is not heavily influenced by a low salt concentration. The boron flux increases linearly with the concentration of boron.more » No element except for boron was permeated through the FO membrane in the multi-component system. The maximum boron flux is obtained in an active layer facing a draw solution orientation of the CTA-ES membrane under conditions of less than pH 7 and high osmotic pressure. (authors)« less

6. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. Looking south from north wall of terminal room. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

6. AN EARLY VIEW OF THE COMPLETE X15 VEHICLE TEST ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. AN EARLY VIEW OF THE COMPLETE X-15 VEHICLE TEST STAND. Looking to the northeast. - Edwards Air Force Base, X-15 Engine Test Complex, Rocket Engine & Complete X-15 Vehicle Test Stands, Rogers Dry Lake, east of runway between North Base & South Base, Boron, Kern County, CA

Ferromagnetism and semiconducting of boron nanowires

PubMed Central

2012-01-01

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

Boron Nitride Nanotubes

NASA Technical Reports Server (NTRS)

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

Boron nitride nanotubes

DOEpatents

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

2012-06-06

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

Plasma boron and the effects of boron supplementation in males.

PubMed Central

Green, N R; Ferrando, A A

1994-01-01

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 < 0.01), lean body mass (p < 0.01), and one repetition maximum (RM) squat (p < 0.001) and one RM bench press (p < 0.01). The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all. PMID:7889885

Microwave sintering of boron carbide

DOEpatents

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

1988-06-10

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

Hydrogen adsorption capacities of multi-walled boron nitride nanotubes and nanotube arrays: a grand canonical Monte Carlo study.

PubMed

Ahadi, Zohreh; Shadman, Muhammad; Yeganegi, Saeed; Asgari, Farid

2012-07-01

Hydrogen adsorption in multi-walled boron nitride nanotubes and their arrays was studied using grand canonical Monte Carlo simulation. The results show that hydrogen storage increases with tube diameter and the distance between the tubes in multi-walled boron nitride nanotube arrays. Also, triple-walled boron nitride nanotubes present the lowest level of hydrogen physisorption, double-walled boron nitride nanotubes adsorb hydrogen better when the diameter of the inner tube diameter is sufficiently large, and single-walled boron nitride nanotubes adsorb hydrogen well when the tube diameter is small enough. Boron nitride nanotube arrays adsorb hydrogen, but the percentage of adsorbed hydrogen (by weight) in boron nitride nanotube arrays is rather similar to that found in multi-walled boron nitride nanotubes. Also, when the Langmuir and Langmuir-Freundlich equations were fitted to the simulated data, it was found that multi-layer adsorptivity occurs more prominently as the number of walls and the tube diameter increase. However, in single-walled boron nitride nanotubes with a small diameter, the dominant mechanism is monolayer adsorptivity.

Boron Stress Activates the General Amino Acid Control Mechanism and Inhibits Protein Synthesis

PubMed Central

Uluisik, Irem; Kaya, Alaattin; Fomenko, Dmitri E.; Karakaya, Huseyin C.; Carlson, Bradley A.; Gladyshev, Vadim N.; Koc, Ahmet

2011-01-01

Boron is an essential micronutrient for plants, and it is beneficial for animals. However, at high concentrations boron is toxic to cells although the mechanism of this toxicity is not known. Atr1 has recently been identified as a boron efflux pump whose expression is upregulated in response to boron treatment. Here, we found that the expression of ATR1 is associated with expression of genes involved in amino acid biosynthesis. These mechanisms are strictly controlled by the transcription factor Gcn4 in response to boron treatment. Further analyses have shown that boron impaired protein synthesis by promoting phosphorylation of eIF2α in a Gcn2 kinase dependent manner. The uncharged tRNA binding domain (HisRS) of Gcn2 is necessary for the phosphorylation of eIF2α in the presence of boron. We postulate that boron exerts its toxic effect through activation of the general amino acid control system and inhibition of protein synthesis. Since the general amino acid control pathway is conserved among eukaryotes, this mechanism of boron toxicity may be of general importance. PMID:22114689

A Hypoxia-Targeted Boron Neutron Capture Therapy Agent for the Treatment of Glioma.

PubMed

Luderer, Micah John; Muz, Barbara; de la Puente, Pilar; Chavalmane, Sanmathi; Kapoor, Vaishali; Marcelo, Raymundo; Biswas, Pratim; Thotala, Dinesh; Rogers, Buck; Azab, Abdel Kareem

2016-10-01

Boron neutron capture therapy (BNCT) has the potential to become a viable cancer treatment modality, but its clinical translation has been limited by the poor tumor selectivity of agents. To address this unmet need, a boronated 2-nitroimidazole derivative (B-381) was synthesized and evaluated for its capability of targeting hypoxic glioma cells. B-381 has been synthesized from a 1-step reaction. Using D54 and U87 glioma cell lines, the in vitro cytotoxicity and cellular accumulation of B-381 has been evaluated under normoxic and hypoxic conditions compared to L-boronophenylalanine (BPA). Furthermore, tumor retention of B-381 was evaluated in vivo. B-381 had low cytotoxicity in normal and cancer cells. Unlike BPA, B-381 illustrated preferential retention in hypoxic glioma cells compared to normoxic glioma cells and normal tissues in vitro. In vivo, B-381 illustrated significantly higher long-term tumor retention compared to BPA, with 9.5-fold and 6.5-fold higher boron levels at 24 and 48 h, respectively. B-381 represents a new class of BNCT agents in which their selectivity to tumors is based on hypoxic tumor metabolism. Further studies are warranted to evaluate B-381 and similar compounds as preclinical candidates for future BNCT clinical trials for the treatment of glioma.

High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties.

PubMed

Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

2015-05-05

For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment.

High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties

NASA Astrophysics Data System (ADS)

Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

2015-05-01

For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment.

Isolation, Solubility, and Characterization of D-Mannitol Esters of 4-Methoxybenzeneboronic Acid.

PubMed

Lopalco, Antonio; Marinaro, William A; Day, Victor W; Stella, Valentino J

2017-02-01

The purpose of this study was to determine the aqueous solubility of a model phenyl boronic acid, 4-methoxybenzeneboronic acid, as a function of pH both in the absence and in the presence of varying D-mannitol concentration. Solid isolated D-mannitol esters were characterized by differential scanning calorimetry, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray studies, and the boronic acid-to-D-mannitol ratio was quantified by HPLC. Hydrolysis of the monoester was studied using UV spectral differences between the monoester and the parent boronic acid. Two D-mannitol esters of 4-methoxybenzeneboronic acid were isolated. The triboronate ester was very insoluble whereas a symmetrical monoboronate monohydrate was also less soluble than the parent. Both esters were crystalline. The monoboronate monohydrate was, however, more soluble than the parent at alkaline pH values due to its lower pKa value (6.53) compared to the parent acid (9.41). Hydrolysis of the monoboronate was extremely fast when even small amount of water was added to dry acetonitrile solutions of the ester. The hydrolysis was buffer concentration dependent and apparent pH sensitive with hydrolysis accelerated by acid. Implications affecting the formulation of future boronic acid drugs are discussed. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Novel passivation dielectrics-The boron- or phosphorus-doped hydrogenated amorphous silicon carbide films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, C.Y.; Fang, Y.K.; Huang, C.F.

1985-02-01

Hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared and studied in a radiofrequency glowdischarge system, using a gas mixture of SiH/sub 4/ and one of the following carbon sources: methane (CH/sub 4/), benzene (C/sub 6/H/sub 6/), toluene (C/sub 7/H/sub 8/), sigma-xylene (C/sub 8/H/sub 10/), trichloroethane (C/sub 2/H/sub 3/Cl/sub 3/), trichloroethylene (C/sub 2/HCl/sub 3/), or carbon tetrachloride (CCl/sub 4/). The effect of doping phosphorus and boron into those a-SiC:H films on chemical etching rate, electrica dc resistivity, breakdown strength, and optical refractive index have been systematically investigated. Their chemical etching properties were examined by immersing in 49% HF, buffered HF,more » 180/sup 0/C H/sub 3/PO/sub 4/ solutions, or in CF/sub 4/ + O/sub 2/ plasma. It was found that the boron-doped a-SiC:H film possesses five times slower etching rate than the undoped one, while phosphorus-doped a-SiC:H film shows about three times slower. Among those a-SiC:H films, the one obtained from a mixture of SiH/sub 4/ and benzene shows the best etch-resistant property, while the ones obtained from a mixture of SiH/sub 4/ and chlorine containing carbon sources (e.g., trichloroethylene, trichloroethane, or carbon tetrachloride) shows that they are poor in etching resistance (i.e., the etching rate is higher). By measuring dc resistivity, dielectric breakdown strength, and effective refractive index, it was found that boron- or phosphorus-doped a-SiC:H films exhibit much higher dielectric strength and resistivity, but lower etching rate, presumably because of higher density.« less

Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

PubMed

Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

2016-12-20

Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

Boric acid increases the expression levels of human anion exchanger genes SLC4A2 and SLC4A3.

PubMed

Akbas, F; Aydin, Z

2012-04-03

Boron is an important micronutrient in plants and animals. The role of boron in living systems includes coordinated regulation of gene expression, growth and proliferation of higher plants and animals. There are several well-defined genes associated with boron transportation and tolerance in plants and these genes show close homology with human anion exchanger genes. Mutation of these genes also characterizes some genetic disorders. We investigated the toxic effects of boric acid on HEK293 cells and mRNA expression of anion exchanger (SLC4A1, SLC4A2 and SLC4A3) genes. Cytotoxicity of boric acid at different concentrations was tested by using the methylthiazolyldiphenyl-tetrazolium bromide assay. Gene expression profiles were examined using quantitative real-time PCR. In the HEK293 cells, the nontoxic upper concentration of boric acid was 250 μM; more than 500 μM caused cytotoxicity. The 250 μM boric acid concentration increased gene expression level of SLC4A2 up to 8.6-fold and SLC4A3 up to 2.6-fold, after 36-h incubation. There was no significant effect of boric acid on SLC4A1 mRNA expression levels.

Highly tunable electronic properties in plasma-synthesized B-doped microcrystalline-to-amorphous silicon nanostructure for solar cell applications

NASA Astrophysics Data System (ADS)

Lim, J. W. M.; Ong, J. G. D.; Guo, Y.; Bazaka, K.; Levchenko, I.; Xu, S.

2017-10-01

Highly controllable electronic properties (carrier mobility and conductivity) were obtained in the sophisticatedly devised, structure-controlled, boron-doped microcrystalline silicon structure. Variation of plasma parameters enabled fabrication of films with the structure ranging from a highly crystalline (89.8%) to semi-amorphous (45.4%) phase. Application of the innovative process based on custom-designed, optimized, remote inductively coupled plasma implied all advantages of the plasma-driven technique and simultaneously avoided plasma-intrinsic disadvantages associated with ion bombardment and overheating. The high degree of SiH4, H2 and B2H6 precursor dissociation ensured very high boron incorporation into the structure, thus causing intense carrier scattering. Moreover, the microcrystalline-to-amorphous phase transition triggered by the heavy incorporation of the boron dopant with increasing B2H6 flow was revealed, thus demonstrating a very high level of the structural control intrinsic to the process. Control over the electronic properties through variation of impurity incorporation enabled tailoring the carrier concentrations over two orders of magnitude (1018-1020 cm-3). These results could contribute to boosting the properties of solar cells by paving the way to a cheap and efficient industry-oriented technique, guaranteeing a new application niche for this new generation of nanomaterials.

Electro-oxidation and characterization of nickel foam electrode for removing boron.

PubMed

Kartikaningsih, Danis; Huang, Yao-Hui; Shih, Yu-Jen

2017-01-01

The electrocoagulation (EC) using metallic Ni foam as electrodes was studied for the removal of boron from solution. The electrolytic parameters were pH (4-12), current density (0.6-2.5 mA cm -2 ), and initial concentration of boron (10-100 mg L -1 ). Experimental results revealed that removal efficiency was maximized at pH 8-9, and decreased as the pH increased beyond that range. At particular onset potentials (0.5-0.8 V vs. Hg/HgO), the micro-granular nickel oxide that was created on the surface of the nickel metal substrate depended on pH, as determined by cyclic voltammetry. Most of the crystallites of the precipitates comprised a mixed phase of β-Ni(OH) 2 , a theophrastite phase, and NiOOH, as revealed by XRD and SEM analyses. A current density of 1.25 mA cm -2 was effective in the EC of boron, and increasing the concentration of boric acid from 10 to 100 mg L -1 did not greatly impair removal efficiency. A kinetic investigation revealed that the reaction followed a pseudo-second order rate model. The optimal conditions under which 99.2% of boron was removed from treated wastewater with 10 mg L -1 -B, leaving less than 0.1 mg L -1 -B in the electrolyte, were pH 8 and 1.25 mA cm -2 for 120 min. Copyright © 2016 Elsevier Ltd. All rights reserved.

Competition between drum and quasi-planar structures in RhB18-: motifs for metallo-boronanotubes and metallo-borophenes.

PubMed

Jian, Tian; Li, Wan-Lu; Chen, Xin; Chen, Teng-Teng; Lopez, Gary V; Li, Jun; Wang, Lai-Sheng

2016-12-01

Metal-doped boron clusters provide new opportunities to design nanoclusters with interesting structures and bonding. A cobalt-doped boron cluster, CoB 18 - , has been observed recently to be planar and can be viewed as a motif for metallo-borophenes, whereas the D 9d drum isomer as a motif for metallo-boronanotubes is found to be much higher in energy. Hence, whether larger doped boron drums are possible is still an open question. Here we report that for RhB 18 - the drum and quasi-planar structures become much closer in energy and co-exist experimentally, revealing a competition between the metallo-boronanotube and metallo-borophene structures. Photoelectron spectroscopy of RhB 18 - shows a complicated spectral pattern, suggesting the presence of two isomers. Quantum chemistry studies indicate that the D 9d drum isomer and a quasi-planar isomer ( C s ) compete for the global minimum. The enhanced stability of the drum isomer in RhB 18 - is due to the less contracted Rh 4d orbitals, which can have favorable interactions with the B 18 drum motif. Chemical bonding analyses show that the quasi-planar isomer of RhB 18 - is aromatic with 10 π electrons, whereas the observed RhB 18 - drum cluster sets a new record for coordination number of eighteen among metal complexes. The current finding shows that the size of the boron drum can be tuned by appropriate metal dopants, suggesting that even larger boron drums with 5d, 6d transition metal, lanthanide or actinide metal atoms are possible.

Boron-based nanostructures: Synthesis, functionalization, and characterization

NASA Astrophysics Data System (ADS)

Bedasso, Eyrusalam Kifyalew

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

Method for preparing boron-carbide articles

DOEpatents

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

1975-10-21

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

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

NASA Astrophysics Data System (ADS)

Durmazuçar, Hasan H.; Gündüz, Güngör

2000-12-01

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

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets.

PubMed

Xue, Yafang; Liu, Qian; He, Guanjie; Xu, Kaibing; Jiang, Lin; Hu, Xianghua; Hu, Junqing

2013-01-24

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices.

Boron nitride - Composition, optical properties, and mechanical behavior

NASA Technical Reports Server (NTRS)

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

1987-01-01

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

Boron nitride: Composition, optical properties and mechanical behavior

NASA Technical Reports Server (NTRS)

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

1987-01-01

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

Dry Process for Manufacturing Hybridized Boron Fiber/Carbon Fiber Thermoplastic Composite Materials from a Solution Coated Precursor

NASA Technical Reports Server (NTRS)

Belvin, Harry L. (Inventor); Cano, Roberto J. (Inventor)

2003-01-01

An apparatus for producing a hybrid boron reinforced polymer matrix composite from precursor tape and a linear array of boron fibers. The boron fibers are applied onto the precursor tapes and the precursor tape processed within a processing component having an impregnation bar assembly. After passing through variable-dimension forming nip-rollers, the precursor tape with the boron fibers becomes a hybrid boron reinforced polymer matrix composite. A driving mechanism is used to pulled the precursor tape through the method and a take-up spool is used to collect the formed hybrid boron reinforced polymer matrix composite.

Synthesis of borophenes: Anisotropic, two-dimensional boron polymorphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mannix, A. J.; Zhou, X. -F.; Kiraly, B.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singha, Bandana; Solanki, Chetan Singh

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

Lattice contraction with boron doping in fully strained SiGe epitaxial layers

NASA Astrophysics Data System (ADS)

Shin, Keun Wook; Song, Sukchan; Kim, Hyun-Woo; Lee, Gun-Do; Yoon, Euijoon

2018-06-01

Changes in lattice constants of epitaxial SiGe layers by boron (B) doping were studied by using high resolution X-ray diffraction (HRXRD) by using SiGe:B with Ge and B concentrations in the range of 11–23% and (1.5–4.2) × 1019 cm‑3, respectively. The lattice contraction coefficient (β) of B in SiGe was measured to be (9.6 ± 0.6) × 10‑24 cm3, which was approximately twice as large as that of B in Si. The ab initio calculation of β, 9.35 × 10‑24 cm3, was in excellent agreement with the experiment. From the ab initio calculation, it is found that the large lattice contraction is due to the favorability of Si–B bond than Si–Ge bond.

Boron neutron capture therapy outcomes for advanced or recurrent head and neck cancer

PubMed Central

Suzuki, Minoru; Kato, Ituro; Aihara, Teruhito; Hiratsuka, Junichi; Yoshimura, Kenichi; Niimi, Miyuki; Kimura, Yoshihiro; Ariyoshi, Yasunori; Haginomori, Shin-ichi; Sakurai, Yoshinori; Kinashi, Yuko; Masunaga, Shin-ichiro; Fukushima, Masanori; Ono, Koji; Maruhashi, Akira

2014-01-01

We retrospectively review outcomes of applying boron neutron capture therapy (BNCT) to unresectable advanced or recurrent head and neck cancers. Patients who were treated with BNCT for either local recurrent or newly diagnosed unresectable head or neck cancers between December 2001 and September 2007 were included. Clinicopathological characteristics and clinical outcomes were retrieved from hospital records. Either a combination of borocaptate sodium and boronophenylalanine (BPA) or BPA alone were used as boron compounds. In all the treatment cases, the dose constraint was set to deliver a dose <10–12 Gy-eq to the skin or oral mucosa. There was a patient cohort of 62, with a median follow-up of 18.7 months (range, 0.7–40.8). A total of 87 BNCT procedures were performed. The overall response rate was 58% within 6 months after BNCT. The median survival time was 10.1 months from the time of BNCT. The 1- and 2-year overall survival (OS) rates were 43.1% and 24.2%, respectively. The major acute Grade 3 or 4 toxicities were hyperamylasemia (38.6%), fatigue (6.5%), mucositis/stomatitis (9.7%) and pain (9.7%), all of which were manageable. Three patients died of treatment-related toxicity. Three patients experienced carotid artery hemorrhage, two of whom had coexistent infection of the carotid artery. This study confirmed the feasibility of our dose-estimation method and that controlled trials are warranted. PMID:23955053

BN Bonded BN fiber article and method of manufacture

DOEpatents

Hamilton, Robert S.

1981-08-18

A boron nitride bonded boron nitride fiber article and the method for its manufacture which comprises forming a shaped article with a composition comprising a bonding compound selected from boron oxide and boric acid and a structural fiber selected from the group consisting of boron oxide, boron nitride and partially nitrided boron oxide fibers, heating the composition in an anhydrous gas to a temperature above the melting point of the compound and nitriding the resulting article in ammonia gas.

Boron hydride polymer coated substrates

DOEpatents

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

1986-08-27

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

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

NASA Technical Reports Server (NTRS)

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2001-01-01

A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

Boron hydride polymer coated substrates

DOEpatents

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

1987-01-01

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

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor

NASA Technical Reports Server (NTRS)

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2000-01-01

A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

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

PubMed Central

Blevins, D G; Lukaszewski, K M

1994-01-01

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

Thermal neutron shield and method of manufacture

DOEpatents

Metzger, Bert Clayton; Brindza, Paul Daniel

2014-03-04

A thermal neutron shield comprising boron shielding panels with a high percentage of the element Boron. The panel is least 46% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of boron shielding panels which includes enriching the pre-cursor mixture with varying grit sizes of Boron Carbide.

Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heber, Elisa M.; Hawthorne, M. Frederick; Kueffer, Peter J.

2014-11-11

Unilamellar liposomes formulated with an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH 3(CH 2)15-7,8-C 2B 9H 11] in the lipid bilayer, and encapsulating Na 3[1-(2’-B 10-H 9)-2-NH 3B 10H 8] were prepared by probe sonication and investigated in vivo. Microwave assisted digestion followed by inductively coupled plasma-optical emission spectroscopy was utilized to determine the biodistribution of boron in various tissues following either a single tail vein injection or two identical injections (separated by 24 hours) of the liposomal suspension in BALB/c mice bearing EMT6 mammary adenocarcinomas in their right flank. Double-injection protocols resulted in a boron content in themore » tumor exceeding 50 µg of boron per gram of tissue for 48 to 72 hours subsequent to the initial injection while tumor:blood boron ratios were more ideal from 54 hours (1.9:1) to 96 hours (5.7:1) subsequent to the initial injection. Tumor bearing mice were given a double-injection of liposomes containing the 10B-enriched analogs of the aforementioned agents and subjected to a 30 minute irradiation by thermal neutrons with a flux of 8.8 x 10 8 (±7%) neutrons/cm 2 s integrated over the energy range of 0.0 – 0.414 eV. Significant tumor response for a single BNCT treatment was demonstrated by growth curves versus a control group. Vastly diminished tumor growth was witnessed at 14 days (186% increase versus 1551% in controls) in mice that were given a second injection/radiation treatment 7 days after the first. Mice given a one hour neutron irradiation following the double-injection of liposomes had a similar response (169% increase at 14 days) suggesting that neutron fluence is the limiting factor towards BNCT efficacy in this study.« less

Nothing Boring About Boron.

PubMed

Pizzorno, Lara

2015-08-01

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

Synthesis, salvage, and catabolism of uridine nucleotides in boron-deficient squash roots.

PubMed

Lovatt, C J; Albert, L S; Tremblay, G C

1981-12-01

Previous work has provided evidence that plants may require boron to maintain adequate levels of pyrimidine nucleotides, suggesting that the state of boron deficiency may actually be one of pyrimidine starvation. Since the availability of pyrimidine nucleotides is influenced by their rates of synthesis, salvage, and catabolism, we compared these activities in the terminal 3 centimeters of roots excised from boron-deficient and -sufficient squash plants (Cucurbita pepo L.). Transferring 5-day-old squash plants to a boron-deficient nutrient solution resulted in cessation of root elongation within 18 hours. However, withholding boron for up to 30 hours did not result in either impaired de novo pyrimidine biosynthesis or a change in the sensitivity of the de novo pathway to regulation by end product inhibition. Boron deprivation had no significant effect on pyrimidine salvage or catabolism. These results provide evidence that boron-deficient plants are not starved for uridine nucleotides collectively. Whether a particular pyrimidine nucleotide or derivative is limiting during boron deprivation remains to be examined.

Asymmetric homologation of boronic esters bearing azido and silyloxy substituents.

PubMed

Singh, R P; Matteson, D S

2000-10-06

In the asymmetric homologation of boronic esters with a (dihalomethyl)lithium, substituents that can bind metal cations tend to interfere. Accordingly, we undertook the introduction of weakly basic oxygen and nitrogen substituents into boronic esters in order to maximize the efficiency of multistep syntheses utilizing this chemistry. Silyloxy boronic esters cannot be made efficiently by direct substitution, but a (hydroxymethyl)boronic ester has been silylated in the usual manner. Conversion of alpha-halo boronic esters to alpha-azido boronic esters has been carried out with sodium azide and a tetrabutylammonium salt as phase-transfer catalyst in a two-phase system with water and either nitromethane or ethyl acetate. These are safer solvents than the previously used dichloromethane, which can form an explosive byproduct with azide ion. Boronic esters containing silyloxy or alkoxy and azido substituents have been shown to react efficiently with (dihalomethyl)lithiums, resulting in efficient asymmetric insertion of the halomethyl group into the carbon-boron bond.

Boron chemicals in diagnosis and therapeutics

PubMed Central

Das, Bhaskar C; Thapa, Pritam; Karki, Radha; Schinke, Caroline; Das, Sasmita; Kambhampati, Suman; Banerjee, Sushanta K; Van Veldhuizen, Peter; Verma, Amit; Weiss, Louis M; Evans, Todd

2013-01-01

Advances in the field of boron chemistry have expanded the application of boron from material use to medicine. Boron-based drugs represent a new class of molecules that possess several biomedical applications including use as imaging agents for both optical and nuclear imaging as well as therapeutic agents with anticancer, antiviral, antibacterial, antifungal and other disease-specific activities. For example, bortezomib (Velcade®), the only drug in clinical use with boron as an active element, was approved in 2003 as a proteasome inhibitor for the treatment of multiple myeloma and non-Hodgkin’s lymphoma. Several other boron-based compounds are in various phases of clinical trials, which illustrates the promise of this approach for medicinal chemists working in the area of boron chemistry. It is expected that in the near future, several boron-containing drugs should become available in the market with better efficacy and potency than existing drugs. This article discusses the current status of the development of boron-based compounds as diagnostic and therapeutic agents in humans. PMID:23617429

Growth kinetics of borided layers: Artificial neural network and least square approaches

NASA Astrophysics Data System (ADS)

Campos, I.; Islas, M.; Ramírez, G.; VillaVelázquez, C.; Mota, C.

2007-05-01

The present study evaluates the growth kinetics of the boride layer Fe 2B in AISI 1045 steel, by means of neural networks and the least square techniques. The Fe 2B phase was formed at the material surface using the paste boriding process. The surface boron potential was modified considering different boron paste thicknesses, with exposure times of 2, 4 and 6 h, and treatment temperatures of 1193, 1223 and 1273 K. The neural network and the least square models were set by the layer thickness of Fe 2B phase, and assuming that the growth of the boride layer follows a parabolic law. The reliability of the techniques used is compared with a set of experiments at a temperature of 1223 K with 5 h of treatment time and boron potentials of 2, 3, 4 and 5 mm. The results of the Fe 2B layer thicknesses show a mean error of 5.31% for the neural network and 3.42% for the least square method.

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers

PubMed Central

Domun, Nadiim; Paton, Keith R.; Sainsbury, Toby; Zhang, Tao; Mohamud, Hibaaq

2017-01-01

In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, GIC, by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly. PMID:29048345

Synthesizing and characterization of titanium diboride for composite bipolar plates in PEM fuel cell

NASA Astrophysics Data System (ADS)

Duddukuri, Ramesh

This research deals with the synthesis and characterization of titanium diboride (TiB2) from novel carbon coated precursors. This work provides information on using different boron sources and their effect on the resulting powders of TiB2. The process has two steps in which the oxide powders were first coated with carbon by cracking of a hydrocarbon gas, propylene (C3H6) and then, mixed with boron carbide and boric acid powders in a stoichiometric ratio. These precursors were treated at temperatures in the range of 1200--1400° C for 2 h in flowing Argon atmosphere to synthesize TiB2. The process utilizes a carbothermic reduction reaction of novel carbon coated precursor that has potential of producing high-quality powders (sub-micrometer and high purity). Single phase TiB2 powders produced, were compared with commercially available titanium diboride using X-ray diffraction and Transmission electron microscopy obtained from boron carbide and boric acid containing carbon coated precursor.

Chemisorption of Hydroxide on 2D Materials From DFT Calculations: Graphene Versus Hexagonal Boron Nitride

PubMed Central

Grosjean, Benoit; Pean, Clarisse; Siria, Alessandro; Bocquet, Lyderic; Vuilleumier, Rodolphe; Bocquet, Marie-Laure

2017-01-01

Recent nanofluidic measurements revealed strongly different surface charge measurements for boron-nitride and graphitic nanotubes when in contact with saline and alkaline water. 1,2 These observations contrast with the similar reactivity of a graphene layer and its boron nitride counterpart, using Density Functional Theory (DFT) framework, for intact and dissociative adsorption of gaseous water molecules. Here, we investigate, by DFT in implicit water, single and multiple adsorption of anionic hydroxide on single layers. A differential adsorption strength is found in vacuum for the first ionic adsorption on the two materials – chemisorbed on BN while physisorbed on graphene. The effect of implicit solvation reduces all adsorption values resulting in a favorable (non-favorable) adsorption on BN (graphene). We also calculate a pKa ≃ 6 for BN in water, in good agreement with experiments. Comparatively, the unfavorable results for graphene in water echoes the weaker surface charge measurements, but points to an alternative scenario. PMID:27809540

Enhancement of Fracture Toughness of Epoxy Nanocomposites by Combining Nanotubes and Nanosheets as Fillers.

PubMed

Domun, Nadiim; Paton, Keith R; Hadavinia, Homayoun; Sainsbury, Toby; Zhang, Tao; Mohamud, Hibaaq

2017-10-19

In this work the fracture toughness of epoxy resin has been improved through the addition of low loading of single part and hybrid nanofiller materials. Functionalised multi-walled carbon nanotubes (f-MWCNTs) was used as single filler, increased the critical strain energy release rate, G IC , by 57% compared to the neat epoxy, at only 0.1 wt% filler content. Importantly, no degradation in the tensile or thermal properties of the nanocomposite was observed compared to the neat epoxy. When two-dimensional boron nitride nanosheets (BNNS) were added along with the one-dimensional f-MWCNTs, the fracture toughness increased further to 71.6% higher than that of the neat epoxy. Interestingly, when functionalised graphene nanoplatelets (f-GNPs) and boron nitride nanotubes (BNNTs) were used as hybrid filler, the fracture toughness of neat epoxy is improved by 91.9%. In neither of these hybrid filler systems the tensile properties were degraded, but the thermal properties of the nanocomposites containing boron nitride materials deteriorated slightly.

Hydrogenated borophene as a stable two-dimensional Dirac material with an ultrahigh Fermi velocity.

PubMed

Xu, Li-Chun; Du, Aijun; Kou, Liangzhi

2016-10-05

The recent synthesis of monolayer borophene (triangular boron monolayer) on a substrate has opened the era of boron nanosheets (Science, 2015, 350, 1513), but the structural instability and a need to explore the novel physical properties are still open issues. Here we demonstrated that borophene can be stabilized by full surface hydrogenation (borophane), from first-principles calculations. Most interestingly, our calculations show that borophane has direction-dependent Dirac cones, which are mainly caused by the in-plane p x and p y orbitals of boron atoms. The Dirac fermions possess an ultrahigh Fermi velocity of up to 3.5 × 10 6 m s -1 under the HSE06 level, which is 4 times higher than that of graphene. The Young's moduli are calculated to be 190 and 120 GPa nm along two different directions, which are comparable to those of steel. The ultrahigh Fermi velocity and good mechanical features render borophane ideal for nanoelectronic applications.

Broadband X-ray edge-enhancement imaging of a boron fibre on lithium fluoride thin film detector

NASA Astrophysics Data System (ADS)

Nichelatti, E.; Bonfigli, F.; Vincenti, M. A.; Cecilia, A.; Vagovič, P.; Baumbach, T.; Montereali, R. M.

2016-10-01

The white beam (∼6-80 keV) available at the TopoTomo X-ray beamline of the ANKA synchrotron facility (KIT, Karlsruhe, Germany) was used to perform edge-enhancement imaging tests on lithium fluoride radiation detectors. The diffracted X-ray image of a microscopic boron fibre, consisting of tungsten wire wrapped by boron cladding, was projected onto lithium fluoride thin films placed at several distances, from contact to 1 m . X-ray photons cause the local formation of primary and aggregate colour centres in lithium fluoride; these latter, once illuminated under blue light, luminesce forming visible-light patterns-acquired by a confocal laser scanning microscope-that reproduce the intensity of the X-ray diffracted images. The tests demonstrated the excellent performances of lithium fluoride films as radiation detectors at the investigated photon energies. The experimental results are here discussed and compared with those calculated with a model that takes into account all the processes that concern image formation, storing and readout.

From coherent quasi-irreversible quantum dynamics towards the second law of thermodynamics: The model boron rotor B13+

NASA Astrophysics Data System (ADS)

Jia, Dongming; Manz, Jörn; Yang, Yonggang

2018-04-01

The planar boron cluster B13+ provides a model to investigate the microscopic origin of the second law of thermodynamics in a small system. It is a molecular rotor with an inner wheel that rotates in an outer bearing. The cyclic reaction path of B13+ passes along thirty equivalent global minimum structures (GMi, i = 1, 2, ..., 30). The GMs are embedded in a cyclic thirty-well potential. They are separated by thirty equivalent transition states with potential barrier Vb. If the boron rotor B13+ is prepared initially in one of the thirty GMs, with energy below Vb, then it tunnels sequentially to its nearest, next-nearest etc. neighbors (520 fs per step) such that all the other GMs get populated. As a consequence, the entropy of occupying the GMs takes about 6 ps to increases from zero to a value close to the maximum value for equi-distribution. Perfect recurrences are practically not observable.

Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oks, Efim M.; Anders, Andre

2012-10-15

Boron-rich plasmas have been obtained using a LaB{sub 6} target in a high power impulse sputtering (HiPIMS) system. The presence of {sup 10}B{sup +}, {sup 11}B{sup +}, Ar{sup 2+}, Ar{sup +}, La{sup 2+}, and La{sup +} and traces of La{sup 3+}, {sup 12}C{sup +}, {sup 14}N{sup +}, and {sup 16}O{sup +} have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by {sup 11}B{sup +} from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV,more » while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and 'recycling'). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.« less

Competition between drum and quasi-planar structures in RhB18 –: motifs for metallo-boronanotubes and metallo-borophenes† †Electronic supplementary information (ESI) available: The photoelectron spectrum of RhB18 – at 266 nm; the top 42 low-lying isomers of RhB18 –; the relative Gibbs free energies, valence molecular orbitals, and coordinates of the two most stable isomers of RhB18 –. See DOI: 10.1039/c6sc02623k Click here for additional data file.

PubMed Central

Jian, Tian; Li, Wan-Lu; Chen, Xin; Chen, Teng-Teng; Lopez, Gary V.

2016-01-01

Metal-doped boron clusters provide new opportunities to design nanoclusters with interesting structures and bonding. A cobalt-doped boron cluster, CoB18 –, has been observed recently to be planar and can be viewed as a motif for metallo-borophenes, whereas the D 9d drum isomer as a motif for metallo-boronanotubes is found to be much higher in energy. Hence, whether larger doped boron drums are possible is still an open question. Here we report that for RhB18 – the drum and quasi-planar structures become much closer in energy and co-exist experimentally, revealing a competition between the metallo-boronanotube and metallo-borophene structures. Photoelectron spectroscopy of RhB18 – shows a complicated spectral pattern, suggesting the presence of two isomers. Quantum chemistry studies indicate that the D 9d drum isomer and a quasi-planar isomer (C s) compete for the global minimum. The enhanced stability of the drum isomer in RhB18 – is due to the less contracted Rh 4d orbitals, which can have favorable interactions with the B18 drum motif. Chemical bonding analyses show that the quasi-planar isomer of RhB18 – is aromatic with 10 π electrons, whereas the observed RhB18 – drum cluster sets a new record for coordination number of eighteen among metal complexes. The current finding shows that the size of the boron drum can be tuned by appropriate metal dopants, suggesting that even larger boron drums with 5d, 6d transition metal, lanthanide or actinide metal atoms are possible. PMID:28451138

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpano, Marina; Perona, Marina; Rodriguez, Carla

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

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

PubMed

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

2015-10-01

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

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

PubMed

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

The versatility of boron in biological target engagement

NASA Astrophysics Data System (ADS)

Diaz, Diego B.; Yudin, Andrei K.

2017-08-01

Boron-containing molecules have been extensively used for the purposes of chemical sensing, biological probe development and drug discovery. Due to boron's empty p orbital, it can coordinate to heteroatoms such as oxygen and nitrogen. This reversible covalent mode of interaction has led to the use of boron as bait for nucleophilic residues in disease-associated proteins, culminating in the approval of new therapeutics that work by covalent mechanisms. Our analysis of a wide range of covalent inhibitors with electrophilic groups suggests that boron is a unique electrophile in its chameleonic ability to engage protein targets. Here we review boron's interactions with a range of protein side-chain residues and reveal that boron's properties are nuanced and arise from its uncommon coordination preferences. These mechanistic and structural insights should serve as a guide for the development of selective boron-based bioactive molecules.

Methylboronic acid fertilization alleviates boron deficiency symptoms in Arabidopsis thaliana.

PubMed

Duran, Catherine; Arce-Johnson, Patricio; Aquea, Felipe

2018-07-01

Our results showed that methylboronic acid is capable of alleviating boron deficiency, enhancing plant growth, and is less toxic than boric acid at higher concentrations. Boron is an essential plant micronutrient and its deficiency occurs in several regions globally, resulting in impaired plant growth. Boron fertilization is a common agricultural practice, but the action range of boron is narrow, sharply transitioning from deficiency to toxicity. Boric acid (BA) is the most common chemical form used in agriculture. In this work, we describe that methylboronic acid (MBA) is capable of alleviating boron deficiency in Arabidopsis. MBA is a boronic acid, but does not naturally occur in soils, necessitating synthesis. Other boronic acids have been described as boron competitors in plants, inhibiting auxin biosynthesis and root development. MBA is more water-soluble than BA and delivers the same amount of boron per molecule. We observed that Arabidopsis seedlings grown in the presence of MBA presented higher numbers of lateral roots and greater main root length compared to plants grown in BA. In addition, root hair length and leaf surface area were increased using MBA as a boron fertilizer. Finally, MBA was less toxic than BA at high concentrations, producing a slight reduction in the main root length but no decrease in total chlorophyll. Our results open a new opportunity to explore the use of a synthetic form of boron in agriculture, providing a tool for future research for plant nutrition.

Boron supercapacitors

DOE PAGES

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

2016-11-16

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

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

PubMed

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

2015-12-18

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

Boron supercapacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhan, Cheng; Zhang, Pengfei; Dai, Sheng

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

Crystalline boron nitride aerogels

DOEpatents

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

2017-04-04

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

Process for making boron nitride using sodium cyanide and boron

DOEpatents

Bamberger, Carlos E.

1990-02-06

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

Process for making boron nitride using sodium cyanide and boron

DOEpatents

Bamberger, Carlos E.

1990-01-01

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

Boron Toxicity Causes Multiple Effects on Malus domestica Pollen Tube Growth.

PubMed

Fang, Kefeng; Zhang, Weiwei; Xing, Yu; Zhang, Qing; Yang, Liu; Cao, Qingqin; Qin, Ling

2016-01-01

Boron is an important micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this toxicity is not known. This study aimed to evaluate the effect of boron toxicity on Malus domestica pollen tube growth and its possible regulatory pathway. Our results showed that a high concentration of boron inhibited pollen germination and tube growth and led to the morphological abnormality of pollen tubes. Fluorescent labeling coupled with a scanning ion-selective electrode technique detected that boron toxicity could decrease [Ca(2+)]c and induce the disappearance of the [Ca(2+)]c gradient, which are critical for pollen tube polar growth. Actin filaments were therefore altered by boron toxicity. Immuno-localization and fluorescence labeling, together with fourier-transform infrared analysis, suggested that boron toxicity influenced the accumulation and distribution of callose, de-esterified pectins, esterified pectins, and arabinogalactan proteins in pollen tubes. All of the above results provide new insights into the regulatory role of boron in pollen tube development. In summary, boron likely plays a structural and regulatory role in relation to [Ca(2+)]c, actin cytoskeleton and cell wall components and thus regulates Malus domestica pollen germination and tube polar growth.

Boron Toxicity Causes Multiple Effects on Malus domestica Pollen Tube Growth

PubMed Central

Fang, Kefeng; Zhang, Weiwei; Xing, Yu; Zhang, Qing; Yang, Liu; Cao, Qingqin; Qin, Ling

2016-01-01

Boron is an important micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this toxicity is not known. This study aimed to evaluate the effect of boron toxicity on Malus domestica pollen tube growth and its possible regulatory pathway. Our results showed that a high concentration of boron inhibited pollen germination and tube growth and led to the morphological abnormality of pollen tubes. Fluorescent labeling coupled with a scanning ion-selective electrode technique detected that boron toxicity could decrease [Ca2+]c and induce the disappearance of the [Ca2+]c gradient, which are critical for pollen tube polar growth. Actin filaments were therefore altered by boron toxicity. Immuno-localization and fluorescence labeling, together with fourier-transform infrared analysis, suggested that boron toxicity influenced the accumulation and distribution of callose, de-esterified pectins, esterified pectins, and arabinogalactan proteins in pollen tubes. All of the above results provide new insights into the regulatory role of boron in pollen tube development. In summary, boron likely plays a structural and regulatory role in relation to [Ca2+]c, actin cytoskeleton and cell wall components and thus regulates Malus domestica pollen germination and tube polar growth. PMID:26955377

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

NASA Astrophysics Data System (ADS)

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.

Characterization of Boron Contamination in Fluorine Implantation using Boron Trifluoride as a Source Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmeide, Matthias; Kondratenko, Serguei

2011-01-07

Fluorine implantation process purity was considered on different types of high current implanters. It was found that implanters equipped with an indirectly heated cathode ion source show an enhanced deep boron contamination compared to a high current implanter using a cold RF-driven multicusp ion source when boron trifluoride is used for fluorine implantations. This contamination is directly related to the source technology and thus, should be considered potentially for any implanter design using hot cathode/hot filament ion source, independently of the manufacturer.The boron contamination results from the generation of double charged boron ions in the arc chamber and the subsequentmore » charge exchange reaction to single charged boron ions taking place between the arc chamber and the extraction electrode. The generation of the double charged boron ions depends mostly on the source parameters, whereas the pressure in the region between the arc chamber and the extraction electrode is mostly responsible for the charge exchange from double charged to single charged ions. The apparent mass covers a wide range, starting at mass 11. A portion of boron ions with energies of (19/11) times higher than fluorine energy has the same magnetic rigidity as fluorine beam and cannot be separated by the analyzer magnet. The earlier described charge exchange effects between the extraction electrode and the entrance to the analyzer magnet, however, generates boron beam with a higher magnetic rigidity compared to fluorine beam and cannot cause boron contamination after mass-separation.The energetic boron contamination was studied as a function of the ion source parameters, such as gas flow, arc voltage, and source magnet settings, as well as analyzing magnet aperture resolution. This allows process optimization reducing boron contamination to the level acceptable for device performance.« less

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

PubMed

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

2016-11-01

Boron removal is an arising issue in desalination plants due to boron's toxicity. As an emerging treatment concept, bioelectrochemical systems (BES) can achieve potentially cost-effective boron removal by taking advantage of cathodic-produced alkali. Prior studies have demonstrated successful removal of boron in microbial desalination cells (MDCs) and microbial fuel cells (MFCs), both of which are representative BES. Herein, mathematical models were developed to further evaluate boron removal by different BES and understand the key operating factors. The models delivered very good prediction of the boron concentration in the MDC integrated with Donnan Dialysis (DD) system with the lowest relative root-mean-square error (RMSE) of 0.00%; the predication of the MFC performance generated the highest RMSE of 18.55%. The model results of salt concentration, solution pH, and current generation were well fitted with experimental data for RMSE values mostly below 10%. The long term simulation of the MDC-DD system suggests that the accumulation of salt in the catholyte/stripping solution could have a positive impact on the removal of boron due to osmosis-driven convection. The current generation in the MDC may have little influence on the boron removal, while in the MFC the current-driven electromigration can contribute up to 40% of boron removal. Osmosis-induced convection transport of boron could be the major driving force for boron removal to a low level <2mgL(-1). The ratio between the anolyte and the catholyte flow rates should be kept >22.2 in order to avoid boron accumulation in the anolyte effluent. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2013-04-01

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

Decreasing boron concentrations in UK rivers: insights into reductions in detergent formulations since the 1990s and within-catchment storage issues.

PubMed

Neal, Colin; Williams, Richard J; Bowes, Michael J; Harrass, Michael C; Neal, Margaret; Rowland, Philip; Wickham, Heather; Thacker, Sarah; Harman, Sarah; Vincent, Colin; Jarvie, Helen P

2010-02-15

The changing patterns of riverine boron concentration are examined for the Thames catchment in southern/southeastern England using data from 1997 to 2007. Boron concentrations are related to an independent marker for sewage effluent, sodium. The results show that boron concentrations in the main river channels have declined with time especially under baseflow conditions when sewage effluent dilution potential is at its lowest. While boron concentrations have reduced, especially under low-flow conditions, this does not fully translate to a corresponding reduction in boron flux and it seems that the "within-catchment" supplies of boron to the river are contaminated by urban sources. The estimated boron reduction in the effluent input to the river based on the changes in river chemistry is typically around 60% and this figure matches with an initial survey of more limited data for the industrial north of England. Data for effluent concentrations at eight sewage treatment works within the Kennet also indicate substantial reductions in boron concentrations: 80% reduction occurred between 2001 and 2008. For the more contaminated rivers there are issues of localised rather than catchment-wide sources and uncertainties over the extent and nature of water/boron stores. Atmospheric sources average around 32 to 61% for the cleaner and 4 to 14% for the more polluted parts. The substantial decreases in the boron concentrations correspond extremely well with the timing and extent of European wide trends for reductions in the industrial and domestic usage of boron-bearing compounds. It clearly indicates that such reductions have translated into lower average and peak concentrations of boron in the river although the full extent of these reductions has probably not yet occurred due to localised stores that are still to deplete.

Modification of the titanium alloy surface in electroexplosive alloying with boron carbide and subsequent electron-beam treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gromov, Victor E., E-mail: gromov@physics.sibsiu.ru; Budovskikh, Evgeniy A., E-mail: budovskikh-ea@physics.sibsiu.ru; Bashchenko, Lyudmila P., E-mail: gromov@physics.sibsiu.ru

2015-10-27

The modification of the VT6 titanium alloy surface in electroexplosion alloying with plasma being formed in titanium foil with a weighed powder of boron carbide with subsequent irradiation by a pulsed electron beam has been carried out. An electroexplosive alloying zone of a thickness up to 50 μm with a gradient structure is found to form. The subsequent electron-beam treatment of the alloying zone results in smoothing of the alloying surface and is accompanied by the formation of the multilayer structure with alternating layers of various alloying degree at a depth of 30 μm.

The potency of electrical energy production from urine by microbial fuel cell using boron-doped diamond electrode

NASA Astrophysics Data System (ADS)

Rahmawati, I.; Ivandini, T. A.; Saepudin, E.

2017-04-01

Microbial fuel cell was developed since it is one of the prospective alternative energy and eco-friendly, using urine as the fuel and Candida fukuyamaensis as a biocatalyst. Boron-doped diamond was used as the electrode. At pH 7, maximum power and current densities of 109.6 mW/m2 and 970 mA/m2 can be obtained, respectively. The results indicated the potency of the system to produce an alternative energy. Furthermore, glucose and creatinine in urine are proposed to be responsible as the carbon sources for the metabolism of C. fukuyamaensis.

Experiments to increase the parameters of the vacuum insulation tandem accelerator for boron neutron capture therapy

NASA Astrophysics Data System (ADS)

Kasatov, D. A.; Kolesnikov, J. A.; Koshkarev, A. M.; Kuznetsov, A. S.; Makarov, A. N.; Sokolova, E. O.; Sorokin, I. N.; Sycheva, T. V.; Taskaev, S. Yu.; Shchudlo, I. M.

2016-12-01

An epithermal neutron source that is based on a vacuum insulation tandem accelerator (VITA) and lithium target was created in the Budker Institute of Nuclear Physics for the development of boron neutron capture therapy (BNCT). A stationary proton beam with 2 MeV energy and 1.6 mA current has been obtained. To carry out BNCT, it is necessary to increase the beam parameters up to 2.3 MeV and 3 mA. Ways to increase the parameters of the proton beam have been proposed and discussed in this paper. The results of the experiments are presented.

Anodic stripping voltammetry of nickel ions and nickel hydroxide nanoparticles at boron-doped diamond electrodes

NASA Astrophysics Data System (ADS)

Musyarofah, N. R. R.; Gunlazuardi, J.; Einaga, Y.; Ivandini, T. A.

2017-04-01

Anodic stripping voltammetry (ASV) of nickel ions in phosphate buffer solution (PBS) have been investigated at boron-doped diamond (BDD) electrodes. The deposition potential at 0.1 V (vs. Ag/AgCl) for 300 s in 0.1 M PBS pH 3 was found as the optimum condition. The condition was applied for the determination of nickel contained in nickel hydroxide nanoparticles. A linear calibration curve can be achieved of Ni(OH)2-NPs in the concentration range of x to x mM with an estimated limit of detection (LOD) of 5.73 × 10-6 mol/L.

6. Credit WCT. Photographic copy of photograph, Advanced Solid Rocket ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. Credit WCT. Photographic copy of photograph, Advanced Solid Rocket Motor (ASRM) test in progress at Test Stand 'E.' It was a JPL/Marshall Space Flight Center project. (JPL negative no. 344-4816 19 February 1982) - Jet Propulsion Laboratory Edwards Facility, Test Stand E, Edwards Air Force Base, Boron, Kern County, CA

Investigations on Mg-borate kinetics and mechanisms during evaporation, dilution and crystallization by Raman spectroscopy

NASA Astrophysics Data System (ADS)

Peng, Jiaoyu; Chen, Jing; Dong, Yaping; Li, Wu

2018-06-01

Raman spectra of boron-concentrated, diluted, and corresponding mother solutions of brine were recorded at 298.15 K. The main polyborate anions present and their interactions in brine during evaporation and dilution were proposed according to the Raman spectra. The polyborate anions B(OH)3, B3O3(OH)4-, B5O6(OH)4-, and B6O7(OH)62- were found to be the main forms in boron-concentrated brine with B3O3(OH)4- ion being the principal form. Diluting brines with water accelerated depolymerization of B5O6(OH)4- and B6O7(OH)62- anions into B(OH)3 and B3O3(OH)4- ions and generated OH- ions, causing the pH of the solutions to increase from 4.2 to almost 8.0. Mg-borates precipitated from all diluted solutions could be classified as either hexaborates or triborates. A mechanism of solid phase transformation was also proposed and discussed based on Raman spectra analysis and solid species and solution pH data.

Chemical and valence reconstruction at the surface of SmB6 revealed by means of resonant soft x-ray reflectometry

NASA Astrophysics Data System (ADS)

Zabolotnyy, V. B.; Fürsich, K.; Green, R. J.; Lutz, P.; Treiber, K.; Min, Chul-Hee; Dukhnenko, A. V.; Shitsevalova, N. Y.; Filipov, V. B.; Kang, B. Y.; Cho, B. K.; Sutarto, R.; He, Feizhou; Reinert, F.; Inosov, D. S.; Hinkov, V.

2018-05-01

Samarium hexaboride (SmB6), a Kondo insulator with mixed valence, has recently attracted much attention as a possible host for correlated topological surface states. Here, we use a combination of x-ray absorption and reflectometry techniques, backed up with a theoretical model for the resonant M4 ,5 absorption edge of Sm and photoemission data, to establish laterally averaged chemical and valence depth profiles at the surface of SmB6. We show that upon cleaving, the highly polar (001) surface of SmB6 undergoes substantial chemical and valence reconstruction, resulting in boron termination and a Sm3 + dominated subsurface region. Whereas at room temperature, the reconstruction occurs on a timescale of less than 2 h, it takes about 24 h below 50 K. The boron termination is eventually established, irrespective of the initial termination. Our findings reconcile earlier depth resolved photoemission and scanning tunneling spectroscopy studies performed at different temperatures and are important for better control of surface states in this system.

SU-D-304-07: Application of Proton Boron Fusion Reaction to Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, J; Yoon, D; Shin, H

Purpose: we present the introduction of a therapy method using the proton boron fusion reaction. The purpose of this study is to verify the theoretical validity of proton boron fusion therapy using Monte Carlo simulations. Methods: 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 thatmore » the effectiveness of the proton boron fusion therapy (PBFT) was verified using Monte Carlo simulations. Results: 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 (BUR). In addition, the 719 keV prompt gamma ray peak produced by the proton boron fusion reaction was positively detected. Conclusion: 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.« less

The Effect of Boronizing on Metallic Alloys for Automotive Applications

NASA Astrophysics Data System (ADS)

Petrova, Roumiana S.; Suwattananont, Naruemon; Samardzic, Veljko

2008-06-01

In this study the wear resistance, corrosion resistance, and oxidation resistance of boronized metallic alloys were investigated. Thermochemical treatment was performed by powder pack boronizing process at temperature 850-950 °C for 4 h. Saw-tooth morphology and smooth interface microstructures were observed with an optical microscope; microhardness was measured across the coating depth. The phases present in the boron coatings depend on the substrate material. High-temperature oxidation resistance was investigated and it was found that boron coating on ferrous alloys can resist temperatures up to 800 °C. The corrosion resistance of the boronized samples was improved and the corrosion rate was calculated for boronized and plain specimens. Wear testing was conducted by following the procedures of ASTM G99, ASTM D2526, and ASTM D4060. The obtained experimental results revealed that boronizing significantly improves the wear-resistance, corrosion-resistance, and oxidation resistance of metallic alloys.

Boron and oxygen-codoped porous carbon as efficient oxygen reduction catalysts

NASA Astrophysics Data System (ADS)

Lei, Zhidan; Chen, Hongbiao; Yang, Mei; Yang, Duanguang; Li, Huaming

2017-12-01

A low-cost boron- and oxygen-codoped porous carbon electrocatalyst towards oxygen reduction reaction (ORR) has been fabricated by a facile one-step pyrolysis approach, while a boron- and oxygen-rich polymer network was used as precursor. The boron- and oxygen-codoped carbon catalyst with high ORR electrocatalytic activity is comparable to that of Pt/C and is superior to that of catalysts doped solely with boron atoms or with oxygen atoms. Furthermore, the optimized boron- and oxygen-codoped carbon catalyst possesses excellent methanol tolerance and long-term durability in alkaline media. The high electrocatalytic activity of the dual-doped carbon catalysts can be attributed to the synergistic effects of high surface area, predominant mesostructure, abundant active oxygen-containing groups, and effective boron doping. The present results show that this boron- and oxygen-codoping strategy could be as a promising way for the preparation of highly efficient ORR catalysts.

Wafer-Scale and Wrinkle-Free Epitaxial Growth of Single-Orientated Multilayer Hexagonal Boron Nitride on Sapphire.

PubMed

Jang, A-Rang; Hong, Seokmo; Hyun, Chohee; Yoon, Seong In; Kim, Gwangwoo; Jeong, Hu Young; Shin, Tae Joo; Park, Sung O; Wong, Kester; Kwak, Sang Kyu; Park, Noejung; Yu, Kwangnam; Choi, Eunjip; Mishchenko, Artem; Withers, Freddie; Novoselov, Kostya S; Lim, Hyunseob; Shin, Hyeon Suk

2016-05-11

Large-scale growth of high-quality hexagonal boron nitride has been a challenge in two-dimensional-material-based electronics. Herein, we present wafer-scale and wrinkle-free epitaxial growth of multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectroscopic investigations and theoretical calculations reveal that synthesized hexagonal boron nitride has a single rotational orientation with AA' stacking order. A facile method for transferring hexagonal boron nitride onto other target substrates was developed, which provides the opportunity for using hexagonal boron nitride as a substrate in practical electronic circuits. A graphene field effect transistor fabricated on our hexagonal boron nitride sheets shows clear quantum oscillation and highly improved carrier mobility because the ultraflatness of the hexagonal boron nitride surface can reduce the substrate-induced degradation of the carrier mobility of two-dimensional materials.

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

PubMed

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

2014-06-24

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

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Boron- and salt-tolerant trees and shrubs for northern Nevada

Treesearch

Heidi Kratsch

2012-01-01

Boron is a mineral that, in small quantities, is essential for plant growth and development , but becomes toxic at levels above 0.5 to 1 part per million (ppm) in the soil. Excess boron may be naturally present in the soil, and it can accumulate by irrigating with water high in boron. Boron occurs naturally in arid soils originating from geologically young deposits. It...

Characterization of boron carbide with an electron microprobe

NASA Technical Reports Server (NTRS)

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.

Chemical disposition of boron in animals and humans.

PubMed Central

Moseman, R F

1994-01-01

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

Geant4 beam model for boron neutron capture therapy: investigation of neutron dose components.

PubMed

Moghaddasi, Leyla; Bezak, Eva

2018-03-01

Boron neutron capture therapy (BNCT) is a biochemically-targeted type of radiotherapy, selectively delivering localized dose to tumour cells diffused in normal tissue, while minimizing normal tissue toxicity. BNCT is based on thermal neutron capture by stable [Formula: see text]B nuclei resulting in emission of short-ranged alpha particles and recoil [Formula: see text]Li nuclei. The purpose of the current work was to develop and validate a Monte Carlo BNCT beam model and to investigate contribution of individual dose components resulting of neutron interactions. A neutron beam model was developed in Geant4 and validated against published data. The neutron beam spectrum, obtained from literature for a cyclotron-produced beam, was irradiated to a water phantom with boron concentrations of 100 μg/g. The calculated percentage depth dose curves (PDDs) in the phantom were compared with published data to validate the beam model in terms of total and boron depth dose deposition. Subsequently, two sensitivity studies were conducted to quantify the impact of: (1) neutron beam spectrum, and (2) various boron concentrations on the boron dose component. Good agreement was achieved between the calculated and measured neutron beam PDDs (within 1%). The resulting boron depth dose deposition was also in agreement with measured data. The sensitivity study of several boron concentrations showed that the calculated boron dose gradually converged beyond 100 μg/g boron concentration. This results suggest that 100μg/g tumour boron concentration may be optimal and above this value limited increase in boron dose is expected for a given neutron flux.

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

PubMed Central

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

2012-01-01

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

Boron

USDA-ARS?s Scientific Manuscript database

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

Boron neutron capture therapy for newly diagnosed glioblastoma multiforme: an assessment of clinical potential

PubMed Central

Sköld, K; Gorlia, T; Pellettieri, L; Giusti, V; H-Stenstam, B; Hopewell, J W

2010-01-01

The purpose of this study was to assess the potential of boron neutron capture therapy (BNCT), with a 6-h infusion of the boron carrier l-boronophenylalanine as a fructose preparation (BPA-f), as first-line radiotherapy for newly diagnosed glioblastoma multiforme (GBM). Patient survival data from a Phase II study using BNCT were compared with retrospective data from the two arms of a Phase III study using conventional radiotherapy (RT) in the reference arm and using RT plus concomitant and adjuvant medication with temozolomide (TMZ) in the experimental arm, and were also compared with small subgroups of these patients for whom the methylation status of the MGMT (O6-methylguanine–DNA methyltransferase) DNA repair gene was known. Differences in the baseline characteristics, salvage therapy after recurrence and levels of severe adverse events were also considered. The results indicate that BNCT offers a treatment that is at least as effective as conventional RT alone. For patients with an unmethylated MGMT DNA repair gene, a possible clinical advantage of BNCT over RT/TMZ was suggested. BNCT is a single-day treatment, which is of convenience to patients, with mild side effects, which would offer an initial 6 weeks of good-quality life during the time when patients would otherwise be undergoing daily treatments with RT and TMZ. It is suggested that the use of BNCT with a 6-h infusion of BPA-f should be explored in a stratified randomised Phase II trial in which patients with the unmethylated MGMT DNA repair gene are offered BNCT in the experimental arm and RT plus TMZ in the reference arm. PMID:20603410

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emiliano C. C. Pozzi; Veronica A. Trivilin; Lucas L. Colombo

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 eachmore » 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.« less

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1993-01-01

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

Magnetron sputtered boron films and Ti/B multilayer structures

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1995-01-01

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

Magnetron sputtered boron films and TI/B multilayer structures

DOEpatents

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

1993-04-20

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

Study of the effects of focused high-energy boron ion implantation in diamond

NASA Astrophysics Data System (ADS)

Ynsa, M. D.; Agulló-Rueda, F.; Gordillo, N.; Maira, A.; Moreno-Cerrada, D.; Ramos, M. A.

2017-08-01

Boron-doped diamond is a material with a great technological and industrial interest because of its exceptional chemical, physical and structural properties. At modest boron concentrations, insulating diamond becomes a p-type semiconductor and at higher concentrations a superconducting metal at low temperature. The most conventional preparation method used so far, has been the homogeneous incorporation of boron doping during the diamond synthesis carried out either with high-pressure sintering of crystals or by chemical vapour deposition (CVD) of films. With these methods, high boron concentration can be included without distorting significantly the diamond crystalline lattice. However, it is complicated to manufacture boron-doped microstructures. A promising alternative to produce such microstructures could be the implantation of focused high-energy boron ions, although boron fluences are limited by the damage produced in diamond. In this work, the effect of focused high-energy boron ion implantation in single crystals of diamond is studied under different irradiation fluences and conditions. Micro-Raman spectra of the sample were measured before and after annealing at 1000 °C as a function of irradiation fluence, for both superficial and buried boron implantation, to assess the changes in the diamond lattice by the creation of vacancies and defects and their degree of recovery after annealing.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Do-Kun; Jung, Joo-Young; Suh, Tae Suk, E-mail: suhsanta@catholic.ac.kr

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 therapymore » 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.« less

Chemical and structural characterization of boron carbide powders and ceramics

NASA Astrophysics Data System (ADS)

Kuwelkar, Kanak Anant

Boron carbide is the material of choice for lightweight armor applications due to its extreme hardness, high Young's modulus and low specific weight. The homogeneity range in boron carbide extends from 9 to 20 at% carbon with the solubility limits not uniquely defined in literature. Over the homogeneity range, the exact lattice positions of boron and carbon atoms have not been unambiguously established, and this topic has been the consideration of significant debate over the last 60 years. The atomic configuration and positions of the boron and carbon atoms play a key role in the crystal structure of the boron carbide phases. Depending on the atomic structure, boron carbide exhibits different mechanical properties which may alter its ballistic performance under extreme dynamic conditions. This work focusses on refinement and development of analytical and chemical methods for an accurate determination of the boron carbide stoichiometry. These methods were then utilized to link structural changes of boron carbide across the solubility range to variations in mechanical properties. After an extensive assessment of the currently employed characterization techniques, it was discerned that the largest source of uncertainty in the determination of the boron carbide stoichiometry was found to arise from the method utilized to evaluate the free carbon concentration. To this end, a modified spiking technique was introduced for free carbon determination where curve fitting techniques were employed to model the asymmetry of the 002 free carbon diffraction peak based on the amorphous, disordered and graphitic nature of carbon. A relationship was then established between the relative intensities of the carbon and boron carbide peaks to the percentage of added carbon and the free-carbon content was obtained by extrapolation. Samples with varying chemistry and high purity were synthesized across the solubility range by hot pressing mixtures of amorphous boron and boron carbide. Vibrational mode frequencies and lattice parameter measurements from Rietveld refinement were correlated to the respective B:C ratios calculated using the developed characterization techniques. An expansion of the unit cell and change in slope in the lattice parameter-stoichiometry relationship were observed at more boron rich stoichiometries. These observations were justified through the proposal of a simplified structural model considering preferential substitution of boron atoms for carbon atoms in the icosahedra from 20 at% to 13.3 at% carbon, followed by formation of B-B bonds from 13.3 at % C to 9 at% C. Hardness measurements uncovered decreased hardness values in boron rich boron carbide which was attributed to the formation of weaker unit cells. Load induced amorphization was also detected in all the indented materials. Finally, experimental observations have shown that failure in boron carbide may be governed by a mechanism other than amorphization and synthesizing boron carbide with a modified microstructure at stoichiometries close to B4C may be the way forward to attain improved ballistic performance.

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

NASA Astrophysics Data System (ADS)

Munhollon, Tyler Lee

Boron carbide is a material of choice for many industrial and specialty applications due to the exceptional properties it exhibits such as high hardness, chemical inertness, low specific gravity, high neutron cross section and more. The combination of high hardness and low specific gravity makes it especially attractive for high pressure/high strain rate applications. However, boron carbide exhibits anomalous behavior when high pressures are applied. Impact pressures over the Hugoniot elastic limit result in catastrophic failure of the material. This failure has been linked to amorphization in cleavage planes and loss of shear strength. Atomistic modeling has suggested boron-rich boron carbide (B13C2) may be a better performing material than the commonly used B4C due to the elimination of amorphization and an increase in shear strength. Therefore, a clear experimental understanding of the factors that lead to the degradation of mechanical properties as well as the effects of chemistry changes in boron carbide is needed. For this reason, the goal of this thesis was to produce high purity boron carbide with varying stoichiometries for chemical and mechanical property characterization. Utilizing rapid carbothermal reduction and pressure assisted sintering, dense boron carbides with varying stoichiometries were produced. Microstructural characteristics such as impurity inclusions, porosity and grain size were controlled. The chemistry and common static mechanical properties that are of importance to superhard materials including elastic moduli, hardness and fracture toughness of the resulting boron-rich boron carbides were characterized. A series of six boron carbide samples were processed with varying amounts of amorphous boron (up to 45 wt. % amorphous boron). Samples with greater than 40 wt.% boron additions were shown to exhibit abnormal sintering behavior, making it difficult to characterize these samples. Near theoretical densities were achieved in samples with less than 40 wt. % amorphous boron additions. X-ray diffraction analysis revealed the samples to be phase pure and boron-rich. Carbon content was determined to be at or near expected values with exception of samples with greater than 40 wt. % amorphous boron additions. Raman microspectroscopy further confirmed the changes in chemistry as well as revealed the chemical homogeneity of the samples. Microstructural analysis carried out using both optical and electron imaging showed clean and consistent microstructures. The changes in the chemistry of the boron carbide samples has been shown to significantly affect the static mechanical properties. Ultrasonic wave speed measurements were used to calculate the elastic moduli which showed a clear decrease in the Young's and shear moduli with a slight increase in bulk modulus. Berkovich nano-indentation revealed a similar trend, as the hardness and fracture toughness of the material decreased with decreasing carbon content. Amorphization within 1 kg Knoop indents was shown to diminish in intensity and extent as carbon content decreased, signifying a mechanism for amorphization mitigation.

Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

NASA Astrophysics Data System (ADS)

Forsthoefel, Kersten M.

Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a molecular precursor and porous alumina templating routes paired with solution-based methodologies are shown to generate non-oxide ceramic nanotubules of boron carbide, boron nitride and silicon carbide compositions. In the final phase of this work, a new metal-catalyzed route to poly(1-alkenyl- o-carborane) homopolymers and related copolymers was developed. Both homopolymers of 1-alkenyl-o-carboranes (1-vinyl-, 1-butenyl-, 1-hexenyl-) and copolymers of 1-hexenyl-o-carborane and allyltrimethylsilane or 1-hexenyl-o-carborane and 6-hexenyldecaborane were synthesized via the Cp2ZrMe2/B(C6F5) 3 catalyst system. A copolymer containing 1-hexenyl-o-carborane and the cross-linking agent, 6-hexenyldecaborane, was synthetically designed which exhibits initial cross-linking at ˜250°C and then converts in 75% yields to boron carbide at 1250°C.

STUDIES OF THE RADIATION CHEMISTRY OF ORGANIC COMPOUNDS. THE RADIOLYSIS OF METHANOL AND METHANOLIC SOLUTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lichtin, N.N.

1961-02-28

>Installation, equipping, and dosimetry of an 850-curie Schwarz-Allen type Co/sup 60/ source were completed. Dose rates are tabulated for six positions in the source. The dissolution of boron from pyrex by methanol was studied using the curcumin procedure. The results indicated <7 x 10/sup -6/M of boron in the methanol independent of irradiations. The gamma radiolysis of methanol resulted in G-values of: 4.66 plus or minus 0.07, H/sub 2/; 0.27 plus or minus 0.03, CH/sub 4/; 1.94 plus or minus 0.06, CH/sub 2/O; and 2.86 plus or minus 0.05, C/sub 2/H/sub 6/O/sub 2/. An improvement in the trapping of methanolmore » resulted in the reduction of the apparent yield of H/sub 2/ to 3.9. (B.O.G.)« less

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

PubMed

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

2011-12-01

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

Concentrations of boron, molybdenum, and selenium in chinook salmon

USGS Publications Warehouse

Hamilton, Steven J.; Wiedmeyer, Raymond H.

1990-01-01

The concentrations of boron, molybdenum, and selenium in young chinook salmon Oncorhynchus tshawytscha were determined in three partial life cycle chronic toxicity studies. In each study, fish were exposed to a mixture of boron, molybdenum, selenate, and selenite in the proportions found in subsurface agricultural drainage water in the basin of the San Joaquin Valley, California. Tests were conducted in well water and in site-specific fresh and brackish waters. No boron or molybdenum was detected in fish exposed to concentrations as high as 6,046 μg boron/L and 193 μg molybdenum/L for 90 d in well water or fresh water; however, whole-body concentrations of selenium increased with increasing exposure concentrations in well water and fresh water, but not in brackish water. Concentrations of selenium in chinook salmon were strongly correlated with reduced survival and growth of fish in well water and with reduced survival in a 15-d seawater challenge test of fish from fresh water. Concentrations of selenium in fish seemed to reach a steady state after 60 d of exposure in well water or fresh water. Fish in brackish water had only background concentrations of selenium after 60 d of exposure, and no effects on survival and growth in brackish water or on survival in a 10-d seawater challenge test were exhibited. This lack of effect in brackish water was attributed to initiation of the study with advanced fry, which were apparently better able to metabolize the trace element mixture than were the younger fish used in studies with well water and fresh water. In all three experimental waters, concentration factors (whole-body concentration/waterborne concentration) for selenium decreased with increasing exposure concentrations, suggesting decreased uptake or increased excretion, or both, of selenium at the higher concentrations.

Recent progress in boron nanomaterials

PubMed Central

Kondo, Takahiro

2017-01-01

Abstract Various types of zero, one, and two-dimensional boron nanomaterials such as nanoclusters, nanowires, nanotubes, nanobelts, nanoribbons, nanosheets, and monolayer crystalline sheets named borophene have been experimentally synthesized and identified in the last 20 years. Owing to their low dimensionality, boron nanomaterials have different bonding configurations from those of three-dimensional bulk boron crystals composed of icosahedra or icosahedral fragments. The resulting intriguing physical and chemical properties of boron nanomaterials are fascinating from the viewpoint of material science. Moreover, the wide variety of boron nanomaterials themselves could be the building blocks for combining with other existing nanomaterials, molecules, atoms, and/or ions to design and create materials with new functionalities and properties. Here, the progress of the boron nanomaterials is reviewed and perspectives and future directions are described. PMID:29152014

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

NASA Technical Reports Server (NTRS)

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.

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

NASA Astrophysics Data System (ADS)

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 deposition chamber. Hexagonal -- BN thin films are successfully deposited using Diborane (B2H6) (5% in H2), Ammonia (NH3) and H2 as precursor gases in the conventional MPECVD mode with and without the negative DC bias. The quality of h-BN in the films improved with pressure and when NH3 used as the first precursor gas in the deposition chamber. c-BN thin films are successfully deposited using Boron-Trifluoride (BF3) (10% in Argon (Ar)), N2, H2, Ar and Helium (He) gases in the electron cyclotron resonance (ECR) mode of the MPECVD system with negative DC bias. Up-to 66% c-BN in the films is achieved under deposition conditions of lower gas flow rates and higher deposition pressures than that reported in the literature for film deposited by ECR-MPECVD. It is shown that the percentage c-BN in the films correlates with the deposition pressure, BF3/H2 ratio and, negative DC bias during nucleation and growth. Diamond thin films are deposited using 60%Ar, 39% H2 and, 1%CH4 at 600°C, 700°C and 800°C substrate temperatures, measured by an IR pyrometer, on Si substrates pre-treated with 3-6nm diamond sol and 20-40mum diamond slurry. Raman spectroscopy, FTIR, X-Ray diffraction (XRD) and, photo-thermal reflectivity methods are used to characterize the thin films. Residual stresses observed for the diamond thin films deposited in this study are tensile in nature and increased with deposition temperature. Better quality diamond films with lower residual stresses are obtained for films deposited on Si substrate pre-treated with 3-6nm diamond sol. Preliminary results on thermal conductivity, k, suggest that k is directly dependent on the deposition temperature and independent of substrate pre-treatment signifying that the nano-seeding technique can be used to replace conventional surface activation technique for diamond seeding where needed.

Transcriptomic analysis of boron hyperaccumulation mechanisms in Puccinellia distans.

PubMed

Öztürk, Saniye Elvan; Göktay, Mehmet; Has, Canan; Babaoğlu, Mehmet; Allmer, Jens; Doğanlar, Sami; Frary, Anne

2018-05-01

Puccinellia distans, common alkali grass, is found throughout the world and can survive in soils with boron concentrations that are lethal for other plant species. Indeed, P. distans accumulates very high levels of this element. Despite these interesting features, very little research has been performed to elucidate the boron tolerance mechanism in this species. In this study, P. distans samples were treated for three weeks with normal (0.5 mg L -1 ) and elevated (500 mg L -1 ) boron levels in hydroponic solution. Expressed sequence tags (ESTs) derived from shoot tissue were analyzed by RNA sequencing to identify genes up and down-regulated under boron stress. In this way, 3312 differentially expressed transcripts were detected, 67.7% of which were up-regulated and 32.3% of which were down-regulated in boron-treated plants. To partially confirm the RNA sequencing results, 32 randomly selected transcripts were analyzed for their expression levels in boron-treated plants. The results agreed with the expected direction of change (up or down-regulation). A total of 1652 transcripts had homologs in A. thaliana and/or O. sativa and mapped to 1107 different proteins. Functional annotation of these proteins indicated that the boron tolerance and hyperaccumulation mechanisms of P. distans involve many transcriptomic changes including: alterations in the malate pathway, changes in cell wall components that may allow sequestration of excess boron without toxic effects, and increased expression of at least one putative boron transporter and two putative aquaporins. Elucidation of the boron accumulation mechanism is important in developing approaches for bioremediation of boron contaminated soils. Copyright © 2018 Elsevier Ltd. All rights reserved.

Back-junction back-contact n-type silicon solar cell with diffused boron emitter locally blocked by implanted phosphorus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Müller, Ralph, E-mail: ralph.mueller@ise.fraunhofer.de; Schrof, Julian; Reichel, Christian

2014-09-08

The highest energy conversion efficiencies in the field of silicon-based photovoltaics have been achieved with back-junction back-contact (BJBC) silicon solar cells by several companies and research groups. One of the most complex parts of this cell structure is the fabrication of the locally doped p- and n-type regions, both on the back side of the solar cell. In this work, we introduce a process sequence based on a synergistic use of ion implantation and furnace diffusion. This sequence enables the formation of all doped regions for a BJBC silicon solar cell in only three processing steps. We observed that implantedmore » phosphorus can block the diffusion of boron atoms into the silicon substrate by nearly three orders of magnitude. Thus, locally implanted phosphorus can be used as an in-situ mask for a subsequent boron diffusion which simultaneously anneals the implanted phosphorus and forms the boron emitter. BJBC silicon solar cells produced with such an easy-to-fabricate process achieved conversion efficiencies of up to 21.7%. An open-circuit voltage of 674 mV and a fill factor of 80.6% prove that there is no significant recombination at the sharp transition between the highly doped emitter and the highly doped back surface field at the device level.« less

A Hypoxia-Targeted Boron Neutron Capture Therapy Agent for the Treatment of Glioma

PubMed Central

Luderer, Micah John; Muz, Barbara; de la Puente, Pilar; Chavalmane, Sanmathi; Kapoor, Vaishali; Marcelo, Raymundo; Biswas, Pratim; Thotala, Dinesh; Rogers, Buck; Azab, Abdel Kareem

2016-01-01

Purpose Boron neutron capture therapy (BNCT) has the potential to become a viable cancer treatment modality, but its clinical translation has been limited by the poor tumor selectivity of agents. To address this unmet need, a boronated 2-nitroimidazole derivative (B-381) was synthesized and evaluated for its capability of targeting hypoxic glioma cells. Methods B-381 has been synthesized from a 1-step reaction. Using D54 and U87 glioma cell lines, the in vitro cytotoxicity and cellular accumulation of B-381 has been evaluated under normoxic and hypoxic conditions compared to L-boronophenylalanine (BPA). Furthermore, tumor retention of B-381 was evaluated in vivo. Results B-381 had low cytotoxicity in normal and cancer cells. Unlike BPA, B-381 illustrated preferential retention in hypoxic glioma cells compared to normoxic glioma cells and normal tissues in vitro. In vivo, B-381 illustrated significantly higher long-term tumor retention compared to BPA, with 9.5-fold and 6.5-fold higher boron levels at 24 and 48 h, respectively. Conclusions B-381 represents a new class of BNCT agents in which their selectivity to tumors is based on tumor hypoxic metabolism, and further studies are warranted to evaluate this compound and similar compounds as preclinical candidates for future BNCT clinical trials for the treatment of glioma. PMID:27401411

Excitation and emission wavelength ratiometric cyanide-sensitive probes for physiological sensing.

PubMed

Badugu, Ramachandram; Lakowicz, Joseph R; Geddes, Chris D

2004-04-01

We characterize three new fluorescent probes that show both spectral shifts and intensity changes in the presence of aqueous cyanide, allowing for both excitation and fluorescence emission wavelength ratiometric and colorimetric sensing. The relatively high binding constants of the probes for cyanide enables a distinct colorimetric change to be visually observed with as little as 10 microM cyanide. The response of the new probes is based on the ability of the boronic acid group to interact with the CN(-) anion, changing from the neutral form of the boronic acid group R-B(OH)(2) to the anionic R-B(-)(OH)3 form, which is an electron-donating group. The presence of an electron-deficient quaternary heterocyclic nitrogen center and a strong electron-donating amino group in the 6 position on the quinolinium backbone provides for the spectral changes observed upon CN(-) complexation. We have determined the binding constants for the ortho-, meta-, and para-boronic acid probes to be 0.12, 0.17, and 0.14 microM(-3). In addition we have synthesized a control compound that does not contain the boronic acid moiety, allowing for structural comparisons and a rationale for the sensing mechanism to be made. Finally we show that the affinity for monosaccharides, such as glucose or fructose, is relatively low as compared to that for cyanide, enabling the potential detection of cyanide in physiologies up to lethal levels.

High hardness BaCb-(BxOy/BN) composites with 3D mesh-like fine grain-boundary structure by reactive spark plasma sintering.

PubMed

Vasylkiv, Oleg; Borodianska, Hanna; Badica, Petre; Grasso, Salvatore; Sakka, Yoshio; Tok, Alfred; Su, Liap Tat; Bosman, Michael; Ma, Jan

2012-02-01

Boron carbide B4C powders were subject to reactive spark plasma sintering (also known as field assisted sintering, pulsed current sintering or plasma assisted sintering) under nitrogen atmosphere. For an optimum hexagonal BN (h-BN) content estimated from X-ray diffraction measurements at approximately 0.4 wt%, the as-prepared BaCb-(BxOy/BN) ceramic shows values of Berkovich and Vickers hardness of 56.7 +/- 3.1 GPa and 39.3 +/- 7.6 GPa, respectively. These values are higher than for the vacuum SPS processed B4C pristine sample and the h-BN -mechanically-added samples. XRD and electronic microscopy data suggest that in the samples produced by reactive SPS in N2 atmosphere, and containing an estimated amount of 0.3-1.5% h-BN, the crystallite size of the boron carbide grains is decreasing with the increasing amount of N2, while for the newly formed lamellar h-BN the crystallite size is almost constant (approximately 30-50 nm). BN is located at the grain boundaries between the boron carbide grains and it is wrapped and intercalated by a thin layer of boron oxide. BxOy/BN forms a fine and continuous 3D mesh-like structure that is a possible reason for good mechanical properties.

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)

PubMed Central

Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

2010-01-01

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding. PMID:21617759

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

Growth and characterization of boron doped graphene by Hot Filament Chemical Vapor Deposition Technique (HFCVD)

NASA Astrophysics Data System (ADS)

Jafari, A.; Ghoranneviss, M.; Salar Elahi, A.

2016-03-01

Large-area boron doped graphene was synthesized on Cu foil (as a catalyst) by Hot Filament Chemical Vapor Deposition (HFCVD) using boron oxide powder and ethanol vapor. To investigate the effect of different boron percentages, grow time and the growth mechanism of boron-doped graphene, scanning electron microscopy (SEM), Raman scattering and X-ray photoelectron spectroscopy (XPS) were applied. Also in this experiment, the I-V characteristic carried out for study of electrical property of graphene with keithley 2361 system. Nucleation of graphene domains with an average domain size of ~20 μm was observed when the growth time is 9 min that has full covered on the Cu surface. The Raman spectroscopy show that the frequency of the 2D band down-shifts with B doping, consistent with the increase of the in-plane lattice constant, and a weakening of the B-C in-plane bond strength relative to that of C-C bond. Also the shifts of the G-band frequencies can be interpreted in terms of the size of the C-C ring and the changes in the electronic structure of graphene in the presence of boron atoms. The study of electrical property shows that by increasing the grow time the conductance increases which this result in agree with SEM images and graphene grain boundary. Also by increasing the boron percentage in gas mixer the conductance decreases since doping graphene with boron creates a band-gap in graphene band structure. The XPS results of B doped graphene confirm the existence of boron in doped graphene, which indicates the boron atoms doped in the graphene lattice are mainly in the form of BC3. The results showed that boron-doped graphene can be successfully synthesized using boron oxide powder and ethanol vapor via a HFCVD method and also chemical boron doping can be change the electrical conductivity of the graphene.

An improved procedure for separation/purification of boron from complex matrices and high-precision measurement of boron isotopes by positive thermal ionization and multicollector inductively coupled plasma mass spectrometry.

PubMed

Wei, Hai-Zhen; Jiang, Shao-Yong; Hemming, N Gary; Yang, Jing-Hong; Yang, Tao; Wu, He-Pin; Yang, Tang-Li; Yan, Xiong; Pu, Wei

2014-06-01

In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs2BO2(+)-static double collection method was developed, ensuring simultaneous collection of (133)Cs2(11)B(16)O2(+)(m/z 309) and (133)Cs2(10)B(16)O2(+) (m/z 308) ions in adjacent H3-H4 Faraday cups with typical zoom optics parameters (Focus Quad: 15 V, Dispersion Quad: -85 V). The external reproducibilities of the measured (11)B/(10)B ratios of the NIST 951 boron standard solutions of 1000 ng, 100 ng and 10 ng of boron by PTIMS method are ±0.06‰, ±0.16‰ and ±0.25‰, respectively, which indicates excellent precision can be achieved for boron isotope measurement at nanogram level boron in natural samples. An on-peak zero blank correction procedure was employed to correct the residual boron signals effect in MC-ICP-MS, which gives consistent δ(11)B values with a mean of 39.66±0.35‰ for seawater in the whole range of boron content from 5 ppb to 200 ppb, ensuring accurate boron isotope analysis in few ppb boron. With the improved protocol, consistent results between TIMS and MC-ICP-MS data were obtained in typical geological materials within a wide span of δ(11)B values ranging from -25‰ to +40‰. Copyright © 2014 Elsevier B.V. All rights reserved.

Dietary boron: possible roles in human and animal physiology

USDA-ARS?s Scientific Manuscript database

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...

Properties of vacuum-evaporated boron films

NASA Technical Reports Server (NTRS)

Feakes, F.

1973-01-01

The work on the properties of thin boron films made by vacuum evaporation of elemental boron using an electron beam as the energy source is reported. The program aimed at characterizing the properties of vacuum evaporated films. The work was directed toward those variables considered to be important in affecting the tensile strength of the boron films. In general, the thickness of the films was less than 0.002 in. The temperature of the substrate on which the boron was condensed was found to be most important. Three distinctly different forms of boron deposit were produced. Although the transition temperature was not sharply defined, at substrate temperatures of less than approximately 600 deg C the boron deposits were amorphous to X-ray. If the substrate were highly polished, the deposits were black and mirror-like. For substrates with coefficients of thermal expansion close to that of boron, the deposits were then continuous and uncracked. The studies suggest that the potential continues to exist for film-type composites to have both high strength and high modulus.

Mechanisms implicated in the effects of boron on wound healing.

PubMed

Nzietchueng, Rosine Mayap; Dousset, Brigitte; Franck, Patricia; Benderdour, Mohamed; Nabet, Pierre; Hess, Ketsia

2002-01-01

Recently, we demonstrated that boron modulates the turnover of the extracellular matrix and increases TNFalpha release. In the present study, we used an in vitro test to investigate the direct effect of boron on specific enzymes (elastase, trypsin-like enzymes, collagenase and alkaline phosphatase) implicated in extracellular matrix turnover. Boron decreased the elastase and alkaline phosphatase activity, but had no effect on trypsin and collagenase activities. The effect of boron on the enzyme activities was also tested in fibroblasts considered as an in vivo test. In contrast to the results obtained in vitro, boron enhanced the trypsin-like, collagenase, and cathepsin D activities in fibroblasts. Boron did not modify the generation of free radicals compared to the control and did not seem to act on the intracellular alkaline phosphatase activity, However, as it did enhance phosphorylation, it can be hypothesized that boron may affect living cells via a mediator, which could be TNFalpha whose transduction signal involves a cascade of phosphorylations.

Global transport of light elements boron and carbon in the full-W ASDEX Upgrade

NASA Astrophysics Data System (ADS)

ASDEX Upgrade Team; Hakola, A.; Likonen, J.; Koivuranta, S.; Krieger, K.; Mayer, M.; Neu, R.; Rohde, V.; Sugiyama, K.

2011-08-01

Transport of carbon and boron has been investigated in the full-W ASDEX Upgrade after experimental campaigns with (2008) and without (2007) boronizations. For this purpose, poloidal deposition profiles of the two elements on tungsten and graphite regions of lower-divertor tiles have been determined. Carbon is mainly deposited in the inner divertor - 80-90% of the determined 12C and 13C inventories on W - while boron shows a much more symmetric deposition profile. In the unboronized machine, the boron inventories are a factor of 10 smaller than in the boronized case and result from residual boron atoms left in the torus prior to the 2007 campaign. Both carbon and boron are deposited more efficiently and/or show less erosion on graphite than on tungsten, particularly in the outer divertor. For 13C, the difference is 10-100 in favor of graphite. This is most probably caused by a higher re-erosion from tungsten surfaces.

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

NASA Astrophysics Data System (ADS)

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

2017-03-01

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

X-ray method shows fibers fail during fatigue of boron-epoxy laminates

NASA Technical Reports Server (NTRS)

Roderick, G. L.; Whitcomb, J. D.

1975-01-01

A method proposed for studying progressive fiber fracture in boron-epoxy laminates during fatigue tests is described. It is based on the intensity of X-ray absorption of the tungsten core in the boron filaments as contrasted with that of the boron and epoxy matrix. When the laminate is X-rayed, the image of the tungsten in the born filaments is recorded on a photographic plate. Breaks in the boron laminates can be easily identified by magnifying the photographic plates. The method is suitable for studying broken boron filaments in most matrix materials, and may supply key information for developing realistic fatigue and fracture models.

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

PubMed

Trivillin, V A; Garabalino, M A; Colombo, L L; González, S J; Farías, R O; Monti Hughes, A; Pozzi, E C C; Bortolussi, S; Altieri, S; Itoiz, M E; Aromando, R F; Nigg, D W; Schwint, A E

2014-06-01

BNCT was proposed for the treatment of diffuse, non-resectable tumors in the lung. We performed boron biodistribution studies with 5 administration protocols employing the boron carriers BPA and/or GB-10 in an experimental model of disseminated lung metastases in rats. All 5 protocols were non-toxic and showed preferential tumor boron uptake versus lung. Absolute tumor boron concentration values were therapeutically useful (25-76ppm) for 3 protocols. Dosimetric calculations indicate that BNCT at RA-3 would be potentially therapeutic without exceeding radiotolerance in the lung. © 2013 Published by Elsevier Ltd.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

D.W. Nigg; Various Others

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

Magnetron sputtered boron films

DOEpatents

Makowiecki, Daniel M.; Jankowski, Alan F.

1998-01-01

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

Low pressure growth of cubic boron nitride films

NASA Technical Reports Server (NTRS)

Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

1997-01-01

A method for forming thin films of cubic boron nitride on substrates at low pressures and temperatures. A substrate is first coated with polycrystalline diamond to provide a uniform surface upon which cubic boron nitride can be deposited by chemical vapor deposition. The cubic boron nitride film is useful as a substitute for diamond coatings for a variety of applications in which diamond is not suitable. any tetragonal or hexagonal boron nitride. The cubic boron nitride produced in accordance with the preceding example is particularly well-suited for use as a coating for ultra hard tool bits and abrasives, especially those intended to use in cutting or otherwise fabricating iron.

Magnetron sputtered boron films

DOEpatents

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

1998-06-16

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

β-Rhombohedral Boron: At the Crossroads of the Chemistry of Boron and the Physics of Frustration [Boron: a frustrated element

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogitsu, Tadashi; Schwegler, Eric; Galli, Giulia

2013-05-08

In the periodic table boron occupies a peculiar, crossover position: on the first row, it is surrounded by metal forming elements on the left and by non-metals on the right. In addition, it is the only non-metal of the third column. Therefore it is perhaps not surprising that the crystallographic structure and topology of its stable allotrope at room temperature (β-boron) are not shared by any other element, and are extremely complex. The formidable intricacy of β- boron, with interconnecting icosahedra, partially occupied sites, and an unusually large number of atoms per unit cell (more than 300) has been knownmore » for more than 40 years. Nevertheless boron remains the only element purified in significant quantities whose ground state geometry has not been completely determined by experiments. However theoretical progress reported in the last decade has shed light on numerous properties of elemental boron, leading to a thorough characterization of its structure at ambient conditions, as well as of its electronic and thermodynamic properties. This review discusses in detail the properties of β-boron, as inferred from experiments and the ab-initio theories developed in the last decade.« less

Boron removal and its concentration in aqueous solution through progressive freeze concentration.

PubMed

Wang, Li Pang

2017-09-01

This study explored the feasibility of progressive freeze concentration in boron removal and its concentration in aqueous solution. The influence of three key parameters in progressive freeze concentration on boron removal and concentration, namely, the advance speed of the ice front, the circumferential velocity of the stirrer, and the initial boron concentration, are investigated by conducting batch experiments. The results show that the effectiveness of boron removal increases with a lower advance speed of the ice front, a higher circumferential velocity of the stirrer, and a lower initial boron concentration. For a model boron solution with an initial concentration of 100 mg/L, the boron concentration in the ice phase after progressive freeze concentration is below 1 mg/L when the advance speed of the ice front is lower than 1 cm/h and the circumferential velocity of the stirrer is higher than 0.12 m/s. In addition, the concentration of boron in the liquid phase occurs simultaneously with progressive freeze concentration. Furthermore, the results also suggest that this method can be applied to the purification and concentration of not only organic molecules but also inorganic ions.

Morphological transformations of BNCO nanomaterials: Role of intermediates

NASA Astrophysics Data System (ADS)

Wang, B. B.; Qu, X. L.; Zhu, M. K.; Levchenko, I.; Baranov, O.; Zhong, X. X.; Xu, S.; Ostrikov, K.

2018-06-01

Highly controllable structural transformation of various doped carbon and boron nitride nanomaterials have been achieved with the perspective of their application in microelectronics, optoelectronics, energy devices and catalytic reactions. Specifically, the syntheses of one-dimensional (1D) boron and nitrogen co-doped tube-like carbon nanorods and 2D vertical carbon and oxygen co-doped boron nitride nanosheets on silicon coated with gold films in N2-H2 plasma was demonstrated. During the synthesis of nanomaterials, boron carbide was used as carbon and boron sources. The results of characterizations by scanning and transmission electron microscopes, as well as micro-Raman and X-ray photoelectron spectroscopes indicate that the formation of different nanomaterials relates to the growth temperature and quantity of boron carbide. Specifically, 1D tube-like carbon nanorods doped with boron and nitrogen are formed at ∼910 °C using a small quantity of boron carbide, while 2D vertical boron nitride nanosheets doped with carbon and oxygen are grown at ∼870 °C using a large quantity of boron carbide. These studies indicate that the behaviors of a reactive intermediate product B2O3 on surfaces of Au nanoparticles play an important role in the formation of different nanomaterials, i.e., whether the B2O3 molecules deposited on Au nanoparticles are desorbed mainly determines the formation of different nanomaterials. The formation of 2D vertical carbon and oxygen co-doped boron nitride nanosheets is related to the high growth rate of edges of nanosheets. Furthermore, the photoluminescence (PL) properties of 1D boron and nitrogen co-doped tube-like carbon nanorods and 2D vertical carbon and oxygen co-doped boron nitride nanosheets were studied at room temperature. The PL results show that all the nanomaterials generate the ultraviolet, blue, green and red PL bands, but the 2D vertical carbon and oxygen co-doped boron nitride nanosheets emit more and stronger PL bands than the 1D boron and nitrogen co-doped tube-like carbon nanorods. The significant differences in the PL properties can be attributed to different carbon structures in these nanomaterials. These achievements can be used to synthesize and control the structures of nanomaterials and contribute to the development of the next generation optoelectronic nanodevices based on 1D and 2D nanomaterials.

Development of neuraminidase detection using gold nanoparticles boron-doped diamond electrodes.

PubMed

Wahyuni, Wulan T; Ivandini, Tribidasari A; Saepudin, Endang; Einaga, Yasuaki

2016-03-15

Gold nanoparticles-modified boron-doped diamond (AuNPs-BDD) electrodes, which were prepared with a self-assembly deposition of AuNPs at amine-terminated boron-doped diamond, were examined for voltammetric detection of neuraminidase (NA). The detection method was performed based on the difference of electrochemical responses of zanamivir at gold surface before and after the reaction with NA in phosphate buffer solution (PBS, pH 5.5). A linear calibration curve for zanamivir in 0.1 M PBS in the absence of NA was achieved in the concentration range of 1 × 10(-6) to 1 × 10(-5) M (R(2) = 0.99) with an estimated limit of detection (LOD) of 2.29 × 10(-6) M. Furthermore, using its reaction with 1.00 × 10(-5) M zanamivir, a linear calibration curve of NA can be obtained in the concentration range of 0-12 mU (R(2) = 0.99) with an estimated LOD of 0.12 mU. High reproducibility was shown with a relative standard deviation (RSD) of 1.14% (n = 30). These performances could be maintained when the detection was performed in mucin matrix. Comparison performed using gold-modified BDD (Au-BDD) electrodes suggested that the good performance of the detection method is due to the stability of the gold particles position at the BDD surface. Copyright © 2016 Elsevier Inc. All rights reserved.

40 CFR Appendix A to Part 68 - Table of Toxic Endpoints

Code of Federal Regulations, 2014 CFR

2014-07-01

... Arsenous trichloride 0.010 7784-42-1 Arsine 0.0019 10294-34-5 Boron trichloride [Borane, trichloro-] 0.010 7637-07-2 Boron trifluoride [Borane, trifluoro-] 0.028 353-42-4 Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro[oxybis[methane

40 CFR Appendix A to Part 68 - Table of Toxic Endpoints

Code of Federal Regulations, 2013 CFR

2013-07-01

... Arsenous trichloride 0.010 7784-42-1 Arsine 0.0019 10294-34-5 Boron trichloride [Borane, trichloro-] 0.010 7637-07-2 Boron trifluoride [Borane, trifluoro-] 0.028 353-42-4 Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro[oxybis[methane

40 CFR Appendix A to Part 68 - Table of Toxic Endpoints

Code of Federal Regulations, 2012 CFR

2012-07-01

... Arsenous trichloride 0.010 7784-42-1 Arsine 0.0019 10294-34-5 Boron trichloride [Borane, trichloro-] 0.010 7637-07-2 Boron trifluoride [Borane, trifluoro-] 0.028 353-42-4 Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro[oxybis[methane

Cobalt Doping of Semiconducting Boron Carbide Using Cobaltocene

DTIC Science & Technology

2007-03-01

COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Lonnie Carlson, Major...DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE THESIS Presented to the Faculty Department of Engineering Physics Graduate School...DISTRIBUTION UNLIMITED AFIT/GNE/ENP/07-01 COBALT DOPING OF SEMICONDUCTING BORON CARBIDE USING COBALTOCENE Lonnie

Method for production of free-standing polycrystalline boron phosphide film

DOEpatents

Baughman, Richard J.; Ginley, David S.

1985-01-01

A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

Methods for boron delivery to mammalian tissue

DOEpatents

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

2003-01-01

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

Lipase-catalyzed highly enantioselective kinetic resolution of boron-containing chiral alcohols.

PubMed

Andrade, Leandro H; Barcellos, Thiago

2009-07-16

The first application of enzymes as catalysts to obtain optically pure boron compounds is described. The kinetic resolution of boron-containing chiral alcohols via enantioselective transesterification catalyzed by lipases was studied. Aromatic, allylic, and aliphatic secondary alcohols containing a boronate ester or boronic acid group were resolved by lipase from Candida antartica (CALB), and excellent E values (E > 200) and high enantiomeric excesses (up to >99%) of both remaining substrates and acetylated product were obtained.

Functional characterization of Citrus macrophylla BOR1 as a boron transporter.

PubMed

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

2013-11-01

Plants have evolved to develop an efficient system of boron uptake and transport using a range of efflux carriers named BOR proteins. In this work we isolated and characterized a boron transporter of citrus (Citrus macrophylla), which was named CmBOR1 for its high homology to AtBOR1. CmBOR1 has 4403 bp and 12 exons. Its coding region has 2145 bp and encodes for a protein of 714 amino acids. CmBOR1 possesses the molecular features of BORs such as an anion exchanger domain and the presence of 10 transmembrane domains. Functional analysis in yeast indicated that CmBOR1 has an efflux boron transporter activity, and transformants have increased tolerance to excess boron. CmBOR1 is expressed in leaves, stem and flowers and shows the greatest accumulation in roots. The transcript accumulation was significantly increased under boron deficiency conditions in shoots. In contrast, the accumulation of the transcript did not change in boron toxicity conditions. Finally, we observed that constitutive expression of CmBOR1 was able to increase tolerance to boron deficiency conditions in Arabidopsis thaliana, suggesting that CmBOR1 is a xylem loading boron transporter. Based on these results, it was determined that CmBOR1 encodes a boric acid/borate transporter involved in tolerance to boron deficiency in plants. © 2013 Scandinavian Plant Physiology Society.

New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications

NASA Astrophysics Data System (ADS)

Guron, Marta

There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly(methylcarbosilane) converted into boron-carbide/silicon-carbide ceramics with high char yields. These polymer blends were also shown to be useful as reagents for synthesis of hafnium-boride/hafnium-carbide/silicon carbide and zirconium-boride/zirconium-carbide/silicon carbide composites.

Electronic structures and thermochemical properties of the small silicon-doped boron clusters B(n)Si (n=1-7) and their anions.

PubMed

Tai, Truong Ba; Kadłubański, Paweł; Roszak, Szczepan; Majumdar, Devashis; Leszczynski, Jerzy; Nguyen, Minh Tho

2011-11-18

We perform a systematic investigation on small silicon-doped boron clusters B(n)Si (n=1-7) in both neutral and anionic states using density functional (DFT) and coupled-cluster (CCSD(T)) theories. The global minima of these B(n)Si(0/-) clusters are characterized together with their growth mechanisms. The planar structures are dominant for small B(n)Si clusters with n≤5. The B(6)Si molecule represents a geometrical transition with a quasi-planar geometry, and the first 3D global minimum is found for the B(7)Si cluster. The small neutral B(n)Si clusters can be formed by substituting the single boron atom of B(n+1) by silicon. The Si atom prefers the external position of the skeleton and tends to form bonds with its two neighboring B atoms. The larger B(7)Si cluster is constructed by doping Si-atoms on the symmetry axis of the B(n) host, which leads to the bonding of the silicon to the ring boron atoms through a number of hyper-coordination. Calculations of the thermochemical properties of B(n)Si(0/-) clusters, such as binding energies (BE), heats of formation at 0 K (ΔH(f)(0)) and 298 K (ΔH(f)([298])), adiabatic (ADE) and vertical (VDE) detachment energies, and dissociation energies (D(e)), are performed using the high accuracy G4 and complete basis-set extrapolation (CCSD(T)/CBS) approaches. The differences of heats of formation (at 0 K) between the G4 and CBS approaches for the B(n)Si clusters vary in the range of 0.0-4.6 kcal mol(-1). The largest difference between two approaches for ADE values is 0.15 eV. Our theoretical predictions also indicate that the species B(2)Si, B(4)Si, B(3)Si(-) and B(7)Si(-) are systems with enhanced stability, exhibiting each a double (σ and π) aromaticity. B(5)Si(-) and B(6)Si are doubly antiaromatic (σ and π) with lower stability. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activation of the EIF2α/ATF4 and ATF6 Pathways in DU-145 Cells by Boric Acid at the Concentration Reported in Men at the US Mean Boron Intake.

PubMed

Kobylewski, Sarah E; Henderson, Kimberly A; Yamada, Kristin E; Eckhert, Curtis D

2017-04-01

Fruits, nuts, legumes, and vegetables are rich sources of boron (B), an essential plant nutrient with chemopreventive properties. Blood boric acid (BA) levels reflect recent B intake, and men at the US mean intake have a reported non-fasting level of 10 μM. Treatment of DU-145 prostate cancer cells with physiological concentrations of BA inhibits cell proliferation without causing apoptosis and activates eukaryotic initiation factor 2 (eIF2α). EIF2α induces cell differentiation and protects cells by redirecting gene expression to manage endoplasmic reticulum stress. Our objective was to determine the temporal expression of endoplasmic reticulum (ER) stress-activated genes in DU-145 prostate cells treated with 10 μM BA. Immunoblots showed post-treatment increases in eIF2α protein at 30 min and ATF4 and ATF6 proteins at 1 h and 30 min, respectively. The increase in ATF4 was accompanied by an increase in the expression of its downstream genes growth arrest and DNA damage-induced protein 34 (GADD34) and homocysteine-induced ER protein (Herp), but a decrease in GADD153/CCAAT/enhancer-binding protein homologous protein (CHOP), a pro-apoptotic gene. The increase in ATF6 was accompanied by an increase in expression of its downstream genes GRP78/BiP, calreticulin, Grp94, and EDEM. BA did not activate IRE1 or induce cleavage of XBP1 mRNA, a target of IRE1. Low boron status has been associated with increased cancer risk, low bone mineralization, and retinal degeneration. ATF4 and BiP/GRP78 function in osteogenesis and bone remodeling, calreticulin is required for tumor suppressor p53 function and mineralization of teeth, and BiP/GRP78 and EDEM prevent the aggregation of misfolded opsins which leads to retinal degeneration. The identification of BA-activated genes that regulate its phenotypic effects provides a molecular underpinning for boron nutrition and biology.

(Pt1-xCux)3Cu2B and Pt9Cu3B5, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

NASA Astrophysics Data System (ADS)

Salamakha, Leonid P.; Sologub, Oksana; Stöger, Berthold; Michor, Herwig; Bauer, Ernst; Rogl, Peter F.

2015-09-01

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt1-xCux)3Cu2B (x=0.33) forms a B-filled β-Mn-type structure (space group P4132; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt9Cu3B5 (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt9Zn3B5-δ-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt6] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt6] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt6] and [Pt6] trigonal prisms, rotated perpendicularly to the central one. There is no B-B contact as well as Cu-B contact in the structure. The relationships of Pt9Cu3B5 structure with the structure of Ti1+xOs2-xRuB2 as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt1-xCux)3Cu2B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ0HC2(0)WHH of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt9Cu3B5 (Pt9Zn3B5-δ-type structure) from electrical resistivity measurements.

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

PubMed

Edward Raja, Chellaiah; Omine, Kiyoshi

2013-08-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawthorne, M. Frederick

2005-04-07

Medical application of boron neutron capture therapy (BNCT) has been significantly hindered by the slow development of boron drug-targeting methodologies for the selective delivery of high boron concentration sto malignant cells. We have successfully sought to fill this need by creating liposomes suitable as in vivo boron delivery vehicles for BNCT. Delivery of therapeutic quantities of boron to tumors in murine models has been achieved with small unilamellar boron-rich liposomes. Subsequently, attempts have been made to improve delivery efficiency of liposomes encapsulating boron-containing water-soluble species into their hollow core by incorporating lipophilic boron compounds as addenda to the liposome bilayer,more » incorporating boron compounds as structural components of the bilayer (which however, poses the risk of sacrificing some stability), and combinations thereof. Regardless of the method, approximately 90% of the total liposome mass remains therapeutically inactive and comprised of the vehicle's construction materials, while less than 5% is boron for neutron targeting. Following this laboratory's intensive study, the observed tumor specificity of certain liposomes has been attributed to their diminutive size of these liposomes (30-150 nm), which enables these small vesicles to pass through the porous, immature vasculature of rapidly growing tumor tissue. We surmised that any amphiphilic nanoparticle of suitable size could possess some tumor selectivity. Consequently, the discovery of a very boron-rich nanoparticle delivery agent with biodistribution performance similar to unilamellar liposomes became one of our goals. Closomers, a new class of polyhedral borane derivatives, attracted us as an alternative BNCT drug-delivery system. We specifically envisioned dodeca (nido-carboranyl)-substituted closomers as possibly having a great potential role in BNCT drug delivery. They could function as extraordinarily boron-rich BNCT drugs since they are 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.« less

Screening of Wheat Genotypes for Boron Efficiency in Bangladesh

USDA-ARS?s Scientific Manuscript database

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

40 CFR 68.130 - List of substances.

Code of Federal Regulations, 2014 CFR

2014-07-01

...,000 a, b Arsenous trichloride 7784-34-1 15,000 b Arsine 7784-42-1 1,000 b Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane

40 CFR 68.130 - List of substances.

Code of Federal Regulations, 2012 CFR

2012-07-01

...,000 a, b Arsenous trichloride 7784-34-1 15,000 b Arsine 7784-42-1 1,000 b Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane

40 CFR 68.130 - List of substances.

Code of Federal Regulations, 2013 CFR

2013-07-01

...,000 a, b Arsenous trichloride 7784-34-1 15,000 b Arsine 7784-42-1 1,000 b Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane

40 CFR 68.130 - List of substances.

Code of Federal Regulations, 2010 CFR

2010-07-01

...,000 a, b Arsenous trichloride 7784-34-1 15,000 b Arsine 7784-42-1 1,000 b Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane

40 CFR 68.130 - List of substances.

Code of Federal Regulations, 2011 CFR

2011-07-01

...,000 a, b Arsenous trichloride 7784-34-1 15,000 b Arsine 7784-42-1 1,000 b Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b Boron trifluoride compound with methyl ether (1:1) [Boron, trifluoro [oxybis [metane

Highly conducting and preferred <220> oriented boron doped nc–Si films for window layers in nc–Si solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondal, Praloy; Das, Debajyoti, E-mail: erdd@iacs.res.in

2016-05-23

Growth and optimization of the boron dopednanocrystalline silicon (nc-Si) films have been studied by varyingthe gaspressure applied to the hydrogendiluted silane plasma in RF (13.56 MHz) plasma-enhanced chemical vapor deposition (PECVD) system, using diborane (B{sub 2}H{sub 6}) as the dopant gas. High magnitudeof electrical conductivity (~10{sup 2} S cm{sup −1}) and<220>orientedcrystallographic lattice planes have been obtained with high crystalline volume fraction (~86 %) at an optimum pressure of 2.5 Torr. XRD and Raman studies reveal good crystallinity with preferred orientation, suitable for applications in stacked layer devices, particularly in nc–Si solar cells.

Thickness determination of few-layer hexagonal boron nitride films by scanning electron microscopy and Auger electron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter, P., E-mail: psutter@bnl.gov; Sutter, E.

2014-09-01

We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

Magnetic tunnel junctions with monolayer hexagonal boron nitride tunnel barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piquemal-Banci, M.; Galceran, R.; Bouzehouane, K.

We report on the integration of atomically thin 2D insulating hexagonal boron nitride (h-BN) tunnel barriers into Co/h-BN/Fe magnetic tunnel junctions (MTJs). The h-BN monolayer is directly grown by chemical vapor deposition on Fe. The Conductive Tip Atomic Force Microscopy (CT-AFM) measurements reveal the homogeneity of the tunnel behavior of our h-BN layers. As expected for tunneling, the resistance depends exponentially on the number of h-BN layers. The h-BN monolayer properties are also characterized through integration into complete MTJ devices. A Tunnel Magnetoresistance of up to 6% is observed for a MTJ based on a single atomically thin h-BN layer.

Nuclear diagnostic for fast alpha particles

DOEpatents

Grisham, Larry R.; Post Jr., Douglass E.; Dawson, John M.

1986-06-03

Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

Nuclear diagnostic for fast alpha particles

DOEpatents

Grisham, Larry R.; Post, Jr., Douglass E.; Dawson, John M.

1986-01-01

Measurement of the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a magnetically contained plasma is provided. The fusion plasma is seeded with energetic boron neutrals for producing, by means of the reaction .sup.10 B (.alpha.,n) .sup.13 N reaction, radioactive nitrogen nuclei which are then collected by a probe. The radioactivity of the probe is then measured by conventional techniques in determining the energy distribution of the alpha particles in the plasma. In a preferred embodiment, diborane gas (B.sub.2 H.sub.6) is the source of the boron neutrals to produce .sup.13 N which decays almost exclusively by positron emission with a convenient half-life of 10 minutes.

Synthesis and in vitro evaluation of thiododecaborated α, α- cycloalkylamino acids for the treatment of malignant brain tumors by boron neutron capture therapy.

PubMed

Hattori, Yoshihide; Kusaka, Shintaro; Mukumoto, Mari; Ishimura, Miki; Ohta, Yoichiro; Takenaka, Hiroshi; Uehara, Kouki; Asano, Tomoyuki; Suzuki, Minoru; Masunaga, Shin-Ichiro; Ono, Koji; Tanimori, Shinji; Kirihata, Mitsunori

2014-12-01

Boron-neutron capture therapy (BNCT) is an attractive technique for cancer treatment. As such, α, α-cycloalkyl amino acids containing thiododecaborate ([B12H11](2-)-S-) units were designed and synthesized as novel boron delivery agents for BNCT. In the present study, new thiododecaborate α, α-cycloalkyl amino acids were synthesized, and biological evaluation of the boron compounds as boron carrier for BNCT was carried out.

Retrospective Study of Selected DoD Materials and Structures Research and Development Programs. Phase 1. Case History Data Collection

DTIC Science & Technology

1979-03-01

made in continuous form by reducing boron trichloride with hydrogen and depositing the elemental boron formed on an electrically heated, continuously...filament take-up unit. A stoichio- metric mixture of boron trichloride and hydrogen is introduced at the top of the reactor. These react at the surface of...fibers are tungsten wire, boron trichloride , and hydrogen gas. The fine diameter tungsten wire on which boron is deposited is an imported product and is

THE BORON-CURCUMIN COMPLEX IN THE DETERMINATION OF TRACE AMOUNTS OF BORON

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayes, M.R.; Metcalfe, J.

1962-12-01

A simple and robust method is described for the formation of the complex of boron with curcumin. The sensitivity of the method is 8.0 to 8.5 x 10/sup -5/ mu g per sq. cm by Sandell's definition. Formation of the complex is believed to be quartitative under the conditions used, and some evidence is given for a ratio of boron to curcumin of 1 to 3. Methods are outlined for determining boron in some metals, compounds, and organic materials. (auth)

Free-standing polycrystalline boron phosphide film and method for production thereof

DOEpatents

Baughman, R.J.; Ginley, D.S.

1982-09-09

A process for producing a free-standing polycrystalline boron phosphide film comprises growing a film of boron phosphide in a vertical growth apparatus on a metal substrate. The metal substrate has a coefficient of thermal expansion sufficiently different from that of boron phosphide that the film separates cleanly from the substrate upon cooling thereof, and the substrate is preferably titanium. The invention also comprises a free-standing polycrystalline boron phosphide film for use in electronic device fabrication.

Mineral resource of the month: boron

USGS Publications Warehouse

Crangle, Robert D.

2012-01-01

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

Protodeboronation of ortho- and para-phenol boronic acids and application to ortho and meta functionalization of phenols using boronic acids as blocking and directing groups.

PubMed

Lee, Chun-Young; Ahn, Su-Jin; Cheon, Cheol-Hong

2013-12-06

The first metal-free thermal protodeboronation of ortho- and para-phenol boronic acids in DMSO was developed. The protodeboronation was successfully applied to the synthesis of ortho- and meta-functionalized phenols using the boronic acid moiety as a blocking group and a directing group, respectively. Mechanistic studies suggested that this protodeboronation proceeds through the coordination of water to the boron atom followed by σ-bond metathesis.

Dispersible shortened boron nitride nanotubes with improved molecule-loading capacity.

PubMed

Zhi, Chunyi; Hanagata, Nobutaka; Bando, Yoshio; Golberg, Dmitri

2011-09-05

The oxidation process of boron nitride nanotubes was thoroughly investigated, and a slow oxidation characteristic was clearly revealed. Subsequently, the controllable oxidation process was utilized to break the sturdy structure of the boron nitride nanotubes to fabricate shortened nanotubes. The shortened boron nitride nanotubes were found to possess good solubility in water and many organic solvents. Further experiments demonstrated remarkably improved molecule-loading capacity of the shortened boron nitride nanotubes. These dispersible shortened boron nitride nanotubes might have the potential to be developed as effective delivery systems for various molecules, which may find applications in bio-related fields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetron sputtered boron films for increasing hardness of a metal surface

DOEpatents

Makowiecki, Daniel M [Livermore, CA; Jankowski, Alan F [Livermore, CA

2003-05-27

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

Biodistribution of boron after intravenous 4-dihydroxyborylphenylalanine-fructose (BPA-F) infusion in meningioma and schwannoma patients: A feasibility study for boron neutron capture therapy.

PubMed

Kulvik, Martti; Kallio, Merja; Laakso, Juha; Vähätalo, Jyrki; Hermans, Raine; Järviluoma, Eija; Paetau, Anders; Rasilainen, Merja; Ruokonen, Inkeri; Seppälä, Matti; Jääskeläinen, Juha

2015-12-01

We studied the uptake of boron after 100 mg/kg BPA infusion in three meningioma and five schwannoma patients as a pre-BNCT feasibility study. With average tumour-to-whole blood boron concentrations of 2.5, we discuss why BNCT could, and probably should, be developed to treat severe forms of the studied tumours. However, analysing 72 tumour and 250 blood samples yielded another finding: the plasma-to-whole blood boron concentrations varied with time, suggesting that the assumed constant boron ratio of 1:1 between normal brain tissue and whole blood deserves re-assessment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermal insulation for high temperature microwave sintering operations and method thereof

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

1995-01-01

Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

Method of preparing thermal insulation for high temperature microwave sintering operations

DOEpatents

Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

1996-01-01

Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

Evolution of anisotropy in bcc Fe distorted by interstitial boron

NASA Astrophysics Data System (ADS)

Gölden, Dominik; Zhang, Hongbin; Radulov, Iliya; Dirba, Imants; Komissinskiy, Philipp; Hildebrandt, Erwin; Alff, Lambert

2018-01-01

The evolution of magnetic anisotropy in bcc Fe as a function of interstitial boron atoms was investigated in thin films grown by molecular beam epitaxy. The thermodynamic nonequilibrium conditions during film growth allowed one to stabilize an interstitial boron content of about 14 at .% accompanied by lattice tetragonalization. The c /a ratio scaled linearly with the boron content up to a maximum value of 1.05 at 300 °C substrate growth temperature, with a room-temperature magnetization of. In contrast to nitrogen interstitials, the magnetic easy axis remained in-plane with an anisotropy of approximately -5.1 ×106erg /cm3 . Density functional theory calculations using the measured lattice parameters confirm this value and show that boron local ordering indeed favors in-plane magnetization. Given the increased temperature stability of boron interstitials as compared to nitrogen interstitials, this study will help to find possible ways to manipulate boron interstitials into a more favorable local order.

Catalytic CVD synthesis of boron nitride and carbon nanomaterials - synergies between experiment and theory.

PubMed

McLean, Ben; Eveleens, Clothilde A; Mitchell, Izaac; Webber, Grant B; Page, Alister J

2017-10-11

Low-dimensional carbon and boron nitride nanomaterials - hexagonal boron nitride, graphene, boron nitride nanotubes and carbon nanotubes - remain at the forefront of advanced materials research. Catalytic chemical vapour deposition has become an invaluable technique for reliably and cost-effectively synthesising these materials. In this review, we will emphasise how a synergy between experimental and theoretical methods has enhanced the understanding and optimisation of this synthetic technique. This review examines recent advances in the application of CVD to synthesising boron nitride and carbon nanomaterials and highlights where, in many cases, molecular simulations and quantum chemistry have provided key insights complementary to experimental investigation. This synergy is particularly prominent in the field of carbon nanotube and graphene CVD synthesis, and we propose here it will be the key to future advances in optimisation of CVD synthesis of boron nitride nanomaterials, boron nitride - carbon composite materials, and other nanomaterials generally.

Combined effect of boron and salinity on water transport: The role of aquaporins.

PubMed

Del Carmen Martínez-Ballesta, Maria; Bastías, Elizabeth; Carvajal, Micaela

2008-10-01

Boron toxicity is an important disorder that can limit plant growth on soils of arid and semi arid environments throughout the world. Although there are several reports about the combined effect of salinity and boron toxicity on plant growth and yield, there is no consensus about the experimental results. A general antagonistic relationship between boron excess and salinity has been observed, however the mechanisms for this interaction is not clear and several options can be discussed. In addition, there is no information, concerning the interaction between boron toxicity and salinity with respect to water transport and aquaporins function in the plants. We recently documented in the highly boron- and salt-tolerant the ecotype of Zea mays L. amylacea from Lluta valley in Northern Chile that under salt stress, the activity of specific membrane components can be influenced directly by boron, regulating the water uptake and water transport through the functions of certain aquaporin isoforms.

Effects of Boron-Based Gel on Radiation-Induced Dermatitis in Breast Cancer: A Double-Blind, Placebo-Controlled Trial.

PubMed

Aysan, Erhan; Idiz, Ufuk Oguz; Elmas, Leyla; Saglam, Esra Kaytan; Akgun, Zuleyha; Yucel, Serap Baskaya

2017-06-01

This study is aimed to evaluate the effects of boron on radiation-induced skin reactions (RISR) in breast cancer patients. After 47 patients with invasive ductal carcinoma underwent radiotherapy, 23 (49%) received a boron-based gel, and 24 (51%) received placebo. Assessments were performed according to the Radiation Therapy Oncology Group (RTOG) skin scale and a Five-Point Horizontal Scale (FPHS). At the end of the fifth week of radiotherapy, the RTOG scores in the boron group were significantly lower than those in the placebo group (p = .024). The FPHS score was higher in the placebo group than in the boron group, and this difference was not statistically significant (p = .079). Using the RTOG scoring system, we revealed that the application of a boron-based gel diminished RISR. The mechanism of action is unclear but may be related to antioxidant, wound healing, and thermal degradation effects of boron.

Rapid transporter regulation prevents substrate flow traffic jams in boron transport

PubMed Central

Sotta, Naoyuki; Duncan, Susan; Tanaka, Mayuki; Sato, Takafumi

2017-01-01

Nutrient uptake by roots often involves substrate-dependent regulated nutrient transporters. For robust uptake, the system requires a regulatory circuit within cells and a collective, coordinated behaviour across the tissue. A paradigm for such systems is boron uptake, known for its directional transport and homeostasis, as boron is essential for plant growth but toxic at high concentrations. In Arabidopsis thaliana, boron uptake occurs via diffusion facilitators (NIPs) and exporters (BORs), each presenting distinct polarity. Intriguingly, although boron soil concentrations are homogenous and stable, both transporters manifest strikingly swift boron-dependent regulation. Through mathematical modelling, we demonstrate that slower regulation of these transporters leads to physiologically detrimental oscillatory behaviour. Cells become periodically exposed to potentially cytotoxic boron levels, and nutrient throughput to the xylem becomes hampered. We conclude that, while maintaining homeostasis, swift transporter regulation within a polarised tissue context is critical to prevent intrinsic traffic-jam like behaviour of nutrient flow. PMID:28870285

Rapid transporter regulation prevents substrate flow traffic jams in boron transport.

PubMed

Sotta, Naoyuki; Duncan, Susan; Tanaka, Mayuki; Sato, Takafumi; Marée, Athanasius Fm; Fujiwara, Toru; Grieneisen, Verônica A

2017-09-05

Nutrient uptake by roots often involves substrate-dependent regulated nutrient transporters. For robust uptake, the system requires a regulatory circuit within cells and a collective, coordinated behaviour across the tissue. A paradigm for such systems is boron uptake, known for its directional transport and homeostasis, as boron is essential for plant growth but toxic at high concentrations. In Arabidopsis thaliana , boron uptake occurs via diffusion facilitators (NIPs) and exporters (BORs), each presenting distinct polarity. Intriguingly, although boron soil concentrations are homogenous and stable, both transporters manifest strikingly swift boron-dependent regulation. Through mathematical modelling, we demonstrate that slower regulation of these transporters leads to physiologically detrimental oscillatory behaviour. Cells become periodically exposed to potentially cytotoxic boron levels, and nutrient throughput to the xylem becomes hampered. We conclude that, while maintaining homeostasis, swift transporter regulation within a polarised tissue context is critical to prevent intrinsic traffic-jam like behaviour of nutrient flow.

Synthesis and biological evaluation of new BSH-conjugated chlorin derivatives as agents for both photodynamic therapy and boron neutron capture therapy of cancer.

PubMed

Asano, Ryuji; Nagami, Amon; Fukumoto, Yuki; Miura, Kaori; Yazama, Futoshi; Ito, Hideyuki; Sakata, Isao; Tai, Akihiro

2014-11-01

New disodium mercaptoundecahydro-closo-dodecaborate (BSH)-conjugated chlorin derivatives 11, 12, 16 and 20 as agents for both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) of cancer were synthesized. The in vivo biodistribution and clearance of 11, 12, 16 and 20 were investigated in tumor-bearing mice. Compounds 12 and 16 showed good tumor-selective accumulation among the four derivatives. The time to maximum accumulation of compound 16 in tumor tissue was one-fourth of that of compound 12, and clearance from normal tissues of compound 16 was similar to that of compound 12. The in vivo therapeutic efficacy of PDT using 16, which has twice as many boron atoms as 12, was evaluated by measuring tumor growth rates in tumor-bearing mice with 660 nm light-emitting diode irradiation at 6h after injection of 16. Tumor growth was significantly inhibited by PDT using 16. These results suggested that 16 is a good candidate for both PDT and BNCT of cancer. Copyright © 2014 Elsevier B.V. All rights reserved.

Feasibility of BNCT radiobiological experiments at the HYTHOR facility

NASA Astrophysics Data System (ADS)

Esposito, J.; Ceballos, C.; Soncin, M.; Fabris, C.; Friso, E.; Moro, D.; Colautti, P.; Jori, G.; Rosi, G.; Nava, E.

2008-06-01

HYTHOR (HYbrid Thermal spectrum sHifter tapirO Reactor) is a new thermal-neutron irradiation facility, which was installed and became operative in mid 2005 at the TAPIRO (TAratura PIla Rapida potenza 0) fast reactor, in the Casaccia research centre (near Rome) of ENEA (Ente per le Nuove tecnologie Energia ed Ambiente). The facility has been designed for in vivo radiobiological studies. In HYTHOR irradiation cavity, 1-6 mice can be simultaneously irradiated to study skin melanoma treatments with the BNCT (boron neutron capture therapy). The therapeutic effects of HYTHOR radiation field on mouse melanoma has been studied as a preliminary investigation before studying the tumour local control due to boron neutron capture effect after boronated molecule injection. The method to properly irradiate small animals has been precisely defined. Results show that HYTHOR radiation field is by itself effective in reducing the tumour-growth rate. This finding has to be taken into account in studying the effectiveness of new 10B carriers. A method to properly measure the reduction of the tumour-growth rate is reported and discussed.

Phase Contrast Imaging of Damage Initiation During Ballistic Impact of Boron Carbide

NASA Astrophysics Data System (ADS)

Schuster, Brian; Tonge, Andrew; Ramos, Kyle; Rigg, Paulo; Iverson, Adam; Schuman, Adam; Lorenzo, Nicholas

2017-06-01

For several decades, flash X-ray imaging has been used to perform time-resolved investigations of the response of ceramics under ballistic impact. Traditional absorption based contrast offers little insight into the early initiation of inelastic deformation mechanisms and instead typically only shows the gross deformation and fracture behavior. In the present work, we employed phase contrast imaging (PCI) at the Dynamic Compression Sector (DCS) at the Advanced Photon Source, Argonne National Laboratory, to investigate crack initiation and propagation following the impact of copper penetrators into boron carbide targets. These experiments employed a single-stage propellant gun to launch small-scale (0.6 mm diameter by 3 mm long) pure copper impactors at velocities ranging from 0.9 to 1.9 km/s into commercially available boron carbide targets that were 8 mm on a side. At the lowest striking velocities the penetrator undergoes dwell or interface defeat and the target response is consistent with the cone crack formation at the impact site. At higher striking velocities there is a distinct transition to massive fragmentation leading to the onset of penetration.

Synthon preference in the cocrystal of 3,4,5-trifluorophenylboronic acid with urea.

PubMed

Kopczyńska, Karolina; Marek, Paulina H; Banaś, Bartłomiej; Madura, Izabela D

2017-11-01

The comprehensive description of the crystal structure of a novel 1:1 cocrystal of 3,4,5-trifluorophenylboronic acid with urea, C 6 H 4 BF 3 O 2 ·CH 4 N 2 O, is presented. Both components are good candidates for crystal engineering as they can create a variety of supramolecular synthons. The preference for the formation of different hetrosynthons is verified based on theoretical calculations. The syn-anti conformation of boronic acid has been found to be the most favourable in the formation of intermolecular interactions with urea. Moreover, the distortions present in the boron coordination sphere have been described quantitatively based on experimental data according to bond-valence vector model calculations. The results revealed that the deformation of the sphere is typical for a syn-anti conformation of boronic acids. The supramolecular structure of the cocrystal is composed of large synthons in the form of layers made up of O-H...O and N-H...O hydrogen bonds. The layers are joined via N-H...F hydrogen bonds which are unusual for urea cocrystal structures.

Ultrathin-shell boron nitride hollow spheres as sorbent for dispersive solid-phase extraction of polychlorinated biphenyls from environmental water samples.

PubMed

Fu, Meizhen; Xing, Hanzhu; Chen, Xiangfeng; Chen, Fan; Wu, Chi-Man Lawrence; Zhao, Rusong; Cheng, Chuange

2014-11-21

Boron nitride hollow spheres with ultrathin-shells were synthesized and used as sorbents for dispersive solid-phase extraction of aromatic pollutants at trace levels from environmental water samples. Polychlorinated biphenyls (PCBs) were selected as target compounds. Sample quantification and detection were performed by gas chromatography-tandem mass spectrometry. Extraction parameters influencing the extraction efficiency were optimized through response surface methodology using the Box-Behnken design. The proposed method achieved good linearity within the concentration range of 0.15-250 ng L(-1) PCBs, low limits of detection (0.04-0.09 ng L(-1), S/N=3:1), good repeatability of the extractions (relative standard deviation, <12%, n=6), and satisfactory recoveries between 84.9% and 101.0% under optimal conditions. Real environmental samples collected from rivers, local lakes, rain and spring waters were analyzed using the developed method. Results demonstrated that the hexagonal boron nitride-based material has significant potential as a sorbent for organic pollutant extraction from environmental water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Novel Composite Proton Exchange Membrane with Connected Long-Range Ionic Nanochannels Constructed via Exfoliated Nafion-Boron Nitride Nanocomposite.

PubMed

Jia, Wei; Tang, Beibei; Wu, Peiyi

2017-05-03

Nafion-boron nitride (NBN) nanocomposites with a Nafion-functionalized periphery are prepared via a convenient and ecofriendly Nafion-assisted water-phase exfoliation method. Nafion and the boron nitride nanosheet present strong interactions in the NBN nanocomposite. Then the NBN nanocomposites were blended with Nafion to prepare NBN Nafion composite proton exchange membranes (PEMs). NBN nanocomposites show good dispersibility and have a noticeable impact on the aggregation structure of the Nafion matrix. Connected long-range ionic nanochannels containing exaggerated (-SO 3 - ) n ionic clusters are constructed during the membrane-forming process via the hydrophilic and H-bonding interactions between NBN nanocomposites and Nafion matrix. The addition of NBN nanocomposites with sulfonic groups also provides additional proton transportation spots and enhances the water uptake of the composite PEMs. The proton conductivity of the NBN Nafion composite PEMs is significantly increased under various conditions relative to that of recast Nafion. At 80 °C-95% relative humidity, the proton conductivity of 0.5 NBN Nafion is 0.33 S·cm -1 , 6 times that of recast Nafion under the same conditions.

Synthesis and formation mechanism of pinnoite in sulfated-type boron concentrated brine by dilution method

NASA Astrophysics Data System (ADS)

Peng, Jiaoyu; Bian, Shaoju; Lin, Feng; Wang, Liping; Dong, Yaping; Li, Wu

2017-10-01

The synthesis of pinnoite (MgB2O(OH)6) in boron-containing brine was established with a novel dilution method. Effects of temperature, precipitation time, boron concentration and mass dilution ratio on the formation of pinnoite were investigated. The products obtained were characterized by X-ray diffraction (XRD), Raman, thermogravimetric and differential scanning calorimeter (TG-DSC), and scanning electron microscopy. The transformation mechanism of pinnoite with different dilution ratios was assumed by studying the crystal growth of pinnoite. The results showed that pinnoite was synthesized above 60 °C in the diluted brine. There were two reaction steps - precipitation of amorphous solid and the formation of pinnoite crystals - during the whole reaction process of pinnoite when the dilution ratio is more than 1.0 at 80 °C. While in the 0.5 diluted brine, only one reaction step of pinnoite crystal formation was observed and its transformation mechanism was discussed based on dissociation of polyborates in brine. Besides, the origin of pinnoite mineral deposited on salt lake bottom was proposed.

The role of boron nitride nanotube as a new chemical sensor and potential reservoir for hydrogen halides environmental pollutants

NASA Astrophysics Data System (ADS)

Yoosefian, Mehdi; Etminan, Nazanin; Moghani, Maryam Zeraati; Mirzaei, Samaneh; Abbasi, Shima

2016-10-01

Density functional theory (DFT) studies on the interaction of hydrogen halides (HX) environmental pollutants and the boron nitride nanotubes (BNNTs) have been reported. To exploit the possibility of BNNTs as gas sensors, the adsorption of hydrogen fluoride (HF), hydrogen chloride (HCl) and hydrogen bromide (HBr) on the side wall of armchair (5,5) boron nitride nanotubes have been investigated. B3LYP/6-31G (d) level were used to analyze the structural and electronic properties of investigate sensor. The adsorption process were interpreted by highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO), quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO) and molecular electrostatic potential (MEP) analysis. Topological parameters of bond critical points have been used to calculate as measure of hydrogen bond (HB) strength. Stronger binding energy, larger charge transfer and charge density illustrate that HF gas possesses chemisorbed adsorption process. The obtained results also show the strongest HB in HF/BNNT complex. We expect that results could provide helpful information for the design of new BNNTs based sensing devices.

Boron-containing amino carboxylic acid compounds and uses thereof

DOEpatents

Kabalka, George W.; Srivastava, Rajiv R.

2000-03-14

Novel compounds which are useful for boron neutron capture therapy (BNCT) are disclosed. The compounds comprise a stable boron-containing group and an aminocycloalkane carboxylic acid group or a boronated acyclic hydrocarbon-linked amino carboxylic acid. Methods for synthesis of the compounds and for use of the compounds in BNCT are disclosed.

Thermal neutron shield and method of manufacture

DOEpatents

Brindza, Paul Daniel; Metzger, Bert Clayton

2013-05-28

A thermal neutron shield comprising concrete with a high percentage of the element Boron. The concrete is least 54% Boron by weight which maximizes the effectiveness of the shielding against thermal neutrons. The accompanying method discloses the manufacture of Boron loaded concrete which includes enriching the concrete mixture with varying grit sizes of Boron Carbide.

Effect of cooling rate during hot stamping on low cyclic fatigue of boron steel sheet

NASA Astrophysics Data System (ADS)

Suh, Chang Hee; Jang, Won Seok; Oh, Sang Kyun; Lee, Rac Gyu; Jung, Yun-Chul; Kim, Young Suk

2012-08-01

Boron steel is widely used throughout the automobile industry due to its high tensile strength and hardenability. When boron steel is used for body parts, only high strength is required for crashworthiness. However, when boron steel is used for chassis parts, a high fatigue life is needed. The microstructure of boron steel is mainly affected by the cooling rate during hot stamping. Therefore, this study investigated the low cyclic fatigue life according to the cooling rate. The fatigue life increased at a low strain amplitude when the cooling rate was fast. However, at a high strain amplitude, the fatigue life decreased, due to the low ductility and fracture toughness of the martensite formed by rapid cooling. Martensite formed by a fast cooling rate shows excellent fatigue life at a low total strain amplitude; however, a multiphase microstructure formed by a slow cooling rate is recommended if the parts experience high and low total strain amplitudes alternately. In addition, the cooling rate has little effect on the distribution of solute boron and boron precipitations, so it is expected that boron rarely affects low cyclic fatigue.

Is Boron a Prebiotic Element? A Mini-review of the Essentiality of Boron for the Appearance of Life on Earth

NASA Astrophysics Data System (ADS)

Scorei, Romulus

2012-02-01

Boron is probably a prebiotic element with special importance in the so-called "sugars world". Boron is not present on Earth in its elemental form. It is found only in compounds, e.g., borax, boric acid, kernite, ulexite, colemanite and other borates. Volcanic spring waters sometimes contain boron-based acids (e.g., boric, metaboric, tetraboric and pyroboric acid). Borates influence the formation of ribofuranose from formaldehyde that feeds the "prebiotic metabolic cycle". The importance of boron in the living world is strongly related to its implications in the prebiotic origins of genetic material; consequently, we believe that throughout the evolution of life, the primary role of boron has been to provide thermal and chemical stability in hostile environments. The complexation of boric acid and borates with organic cis-diols remains the most probable chemical mechanism for the role of this element in the evolution of the living world. Because borates can stabilize ribose and form borate ester nucleotides, boron may have provided an essential contribution to the "pre-RNA world".

Where Boron? Mars Rover Detects It

NASA Image and Video Library

2016-12-13

This map shows the route driven by NASA's Curiosity Mars rover (blue line) and locations where the rover's Chemistry and Camera (ChemCam) instrument detected the element boron (dots, colored by abundance of boron according to the key at right). The main map shows the traverse from landing day (Sol 0) in August 2012 to the rover's location in September 2016, with boron detections through September 2015. The inset at upper left shows a magnified version of the most recent portion of that traverse, with boron detections during that portion. Overlapping dots represent cases when boron was detected in multiple ChemCam observation points in the same target and non-overlapping dots represent cases where two different targets in the same location have boron. Most of the mission's detections of boron have been made in the most recent seven months (about 200 sols) of the rover's uphill traverse. The base image for the map is from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. North is up. The scale bar at lower right represents one kilometer (0.62 mile). http://photojournal.jpl.nasa.gov/catalog/PIA21150

Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru

Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereasmore » for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.« less

Boron investigation survey, March Air Force Base, California. Final report, 27 Jan-7 Feb 92

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garland III , J.G.

1992-07-01

Armstrong Laboratory conducted a field survey to investigate the source of boron in the March AFB CA wastewater treatment plant effluent. The survey measured boron contributions from drinking water, domestic sources, and industrial sources over a 10-day period. The survey also evaluated the effluent to the treatment plant over the same 10 days. Boron results at the regulatory discharge point averaged 0.48 mg/1, which complies with the base permit. The results also showed drinking water levels averaged 0.225 mg/1, domestic contribution combined with drinking water levels averaged 0.396 mg/1, and mixed industrial and domestic levels ranged from 0.246 mg/1 tomore » 1.84 mg/1. The report presents bulk boron sample results from a variety of soaps and bleaches. Recommendations include further investigation into industrial activity generating high boron levels, discouraging the use of boron-containing products by military, contract, and domestic users and negotiating with the regulating agency for permitting boron at a higher level.« less

The Boron Efflux Transporter ROTTEN EAR Is Required for Maize Inflorescence Development and Fertility[C][W][OPEN

PubMed Central

Chatterjee, Mithu; Tabi, Zara; Galli, Mary; Malcomber, Simon; Buck, Amy; Muszynski, Michael; Gallavotti, Andrea

2014-01-01

Although boron has a relatively low natural abundance, it is an essential plant micronutrient. Boron deficiencies cause major crop losses in several areas of the world, affecting reproduction and yield in diverse plant species. Despite the importance of boron in crop productivity, surprisingly little is known about its effects on developing reproductive organs. We isolated a maize (Zea mays) mutant, called rotten ear (rte), that shows distinct defects in vegetative and reproductive development, eventually causing widespread sterility in its inflorescences, the tassel and the ear. Positional cloning revealed that rte encodes a membrane-localized boron efflux transporter, co-orthologous to the Arabidopsis thaliana BOR1 protein. Depending on the availability of boron in the soil, rte plants show a wide range of phenotypic defects that can be fully rescued by supplementing the soil with exogenous boric acid, indicating that rte is crucial for boron transport into aerial tissues. rte is expressed in cells surrounding the xylem in both vegetative and reproductive tissues and is required for meristem activity and organ development. We show that low boron supply to the inflorescences results in widespread defects in cell and cell wall integrity, highlighting the structural importance of boron in the formation of fully fertile reproductive organs. PMID:25035400

The boron content of selected foods and the estimation of its daily intake among free-living subjects.

PubMed

Naghii, M R; Wall, P M; Samman, S

1996-12-01

Boron is an essential micronutrient for higher plants. The results of studies in animals and humans have suggested a potential role for boron as a modulator of the steroid hormone pathway. As part of a study to obtain baseline information on boron in humans, the boron content of selected foods (66 items) consumed in Australia was determined. Mean values are presented for the element per 100 g or 100 ml of food and per serving. Major sources of the element were nuts, dried fruits, legumes, fresh vegetables and fruits. The boron content of these foods correlated positively and strongly with values provided by the comprehensive Finnish Tables of mineral composition of foods and with the US Food and Drug Administration Total Diet Study. Because of the similarity in methods employed by this study and that used for the comprehensive Finnish Tables, the latter was used to analyze the boron content in 7-day weighed food records of 32 subjects. Using data obtained from the food records and assigning the corresponding values from the Finnish Tables for the boron content of foods, the average daily consumption of boron for a selected group of Australians was found to be 2.23 +/- 1.23 mg/day.

Controlled growth of semiconductor crystals

DOEpatents

Bourret-Courchesne, Edith D.

1992-01-01

A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

Controlled growth of semiconductor crystals

DOEpatents

Bourret-Courchesne, E.D.

1992-07-21

A method is disclosed for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B[sub x]O[sub y] are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T[sub m1] of the oxide of boron (T[sub m1]=723 K for boron oxide B[sub 2]O[sub 3]), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T[sub m2] of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm[sup 2]. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 [mu]m. 7 figs.

Fillers for improved graphite fiber retention by polymer matrix composites

NASA Technical Reports Server (NTRS)

House, E. E.; Sheppard, C. H.

1981-01-01

The results of a program designed to determine the extent to which elemental boron and boron containing fillers added to the matrix resin of graphite/epoxy composites prevent the release of graphite fibers when the composites are exposed to fire and impact conditions are described. The fillers evaluated were boron, boron carbide and aluminum boride. The conditions evaluated were laboratory simulations of those that could exist in the event of an aircraft crash and burn situation. The baseline (i.e., unfilled) laminates evaluated were prepared from commercially available graphite/epoxy. The baseline and filled laminates' mechanical properties, before and after isothermal and humidity aging, also were compared. It was found that a small amount of graphite fiber was released from the baseline graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that the addition of boron and boron containing fillers to the resin matrix eliminated this fiber release. Mechanical properties of laminates containing the boron and boron containing fillers were lower than those of the baseline laminates. These property degradations for two systems: boron (5 micron) at 2.5 percent filler loading, and boron (5 micron) at 5.0 percent filler loading do not appear severe enough to preclude their use in structural composite applications.

Static and Dynamic Behavior of High Modulus Hybrid Boron/Glass/Aluminum Fiber Metal Laminates

NASA Astrophysics Data System (ADS)

Yeh, Po-Ching

2011-12-01

This dissertation presents the investigation of a newly developed hybrid fiber metal laminates (FMLs) which contains commingled boron fibers, glass fibers, and 2024-T3 aluminum sheets. Two types of hybrid boron/glass/aluminum FMLs are developed. The first, type I hybrid FMLs, contained a layer of boron fiber prepreg in between two layers of S2-glass fiber prepreg, sandwiched by two aluminum alloy 2024-T3 sheets. The second, type II hybrid FMLs, contained three layer of commingled hybrid boron/glass fiber prepreg layers, sandwiched by two aluminum alloy 2024-T3 sheets. The mechanical behavior and deformation characteristics including blunt notch strength, bearing strength and fatigue behavior of these two types of hybrid boron/glass/aluminum FMLs were investigated. Compared to traditional S2-glass fiber reinforced aluminum laminates (GLARE), the newly developed hybrid boron/glass/aluminum fiber metal laminates possess high modulus, high yielding stress, and good blunt notch properties. From the bearing test result, the hybrid boron/glass/aluminum fiber metal laminates showed outstanding bearing strength. The high fiber volume fraction of boron fibers in type II laminates lead to a higher bearing strength compared to both type I laminates and traditional GLARE. Both types of hybrid FMLs have improved fatigue crack initiation lives and excellent fatigue crack propagation resistance compared to traditional GLARE. The incorporation of the boron fibers improved the Young's modulus of the composite layer in FMLs, which in turn, improved the fatigue crack initiation life and crack propagation rates of the aluminum sheets. Moreover, a finite element model was established to predict and verify the properties of hybrid boron/glass/aluminum FMLs. The simulated results showed good agreement with the experimental results.

Arsenic, Boron, and Fluoride Concentrations in Ground Water in and Near Diabase Intrusions, Newark Basin, Southeastern Pennsylvania

USGS Publications Warehouse

Senior, Lisa A.; Sloto, Ronald A.

2006-01-01

During an investigation in 2000 by the U.S. Environmental Protection Agency (USEPA) of possible contaminant releases from an industrial facility on Congo Road near Gilbertsville in Berks and Montgomery Counties, southeastern Pennsylvania, concentrations of arsenic and fluoride above USEPA drinking-water standards of 10 ?g/L and 4 mg/L, respectively, and of boron above the USEPA health advisory level of 600 ?g/L were measured in ground water in an area along the northwestern edge of the Newark Basin. In 2003, the USEPA requested technical assistance from the U.S. Geological Survey (USGS) to help identify sources of arsenic, boron, and fluoride in the ground water in the Congo Road area, which included possible anthropogenic releases and naturally occurring mineralization in the local bedrock aquifer, and to identify other areas in the Newark Basin of southeastern Pennsylvania with similarly elevated concentrations of these constituents. The USGS reviewed available data and collected additional ground-water samples in the Congo Road area and four similar hydrogeologic settings. The Newark Basin is the largest of the 13 major exposed Mesozoic rift basins that stretch from Nova Scotia to South Carolina. Rocks in the Newark Basin include Triassic through Jurassic-age sedimentary sequences of sandstones and shales that were intruded by diabase. Mineral deposits of hydrothermal origin are associated with alteration zones bordering intrusions of diabase and also occur as strata-bound replacement deposits of copper and zinc in sedimentary rocks. The USGS review of data available in 2003 showed that water from about 10 percent of wells throughout the Newark Basin of southeastern Pennsylvania had concentrations of arsenic greater than the USEPA maximum contaminant level (MCL) of 10 ?g/L; the highest reported arsenic concentration was at about 70 ?g/L. Few data on boron were available, and the highest reported boron concentration in well-water samples was 60 ?g/L in contrast to concentrations over 5,000 ?g/L in the Congo Road area. Although concentrations of fluoride up to 4 mg/L were reported for a few well-water samples collected throughout the Newark Basin, about 90 percent of the samples had concentrations of 0.5 mg/L or less. The USGS sampled 58 wells primarily in 5 areas in the Newark Basin, southeastern Pennsylvania, from February 2004 through April 2005 to identify other possible areas of elevated arsenic, boron, and fluoride and to characterize the geochemical environment associated with elevated concentrations of these constituents. Sampled wells included 12 monitor wells at an industrial facility near Congo Road, 45 private-supply wells in Berks, Montgomery, and Bucks Counties, and 1 private-supply well near Dillsburg, York County, an area where elevated fluoride in ground water had been reported in the adjacent Gettysburg Basin. Wells were sampled in transects from the diabase through the adjacent hornfels and into the unaltered shales of the Brunswick Group. Field measurements were made of pH, temperature, dissolved oxygen concentration, and specific conductance. Samples were analyzed in the laboratory for major ions, nutrients, total organic carbon, dissolved and total concentrations of selected trace elements, and boron isotopic composition. Generally, the ground water from the 46 private-supply wells had relatively neutral to alkaline pH (ranging from 6.1 to 9.1) and moderate concentrations of dissolved oxygen. Most water samples were of the calcium-bicarbonate type. Concentrations of arsenic up to 60 ?g/L, boron up to 3,950 ?g/L, and fluoride up to 0.70 mg/L were measured. Drinking-water standards or health advisories (for constituents that do not have standards established) were exceeded most frequently (about 20 percent of samples) for arsenic and boron and less frequently (6 percent or less of samples) for total iron, manganese, sulfate, nitrate, lead, molybdenum, and strontium. In water from 12 monitor

Removal of boron from ceramic industry wastewater by adsorption-flocculation mechanism using palm oil mill boiler (POMB) bottom ash and polymer.

PubMed

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 reduced to 3 mg/L and 5 mg/L respectively, satisfying the discharge requirement by Malaysia Department of Environment (DOE). The modeling study shows that the adsorption isotherm of boron onto POMB bottom ash conformed to the Freundlich Isotherm. The proposed method is suitable for boron removal in ceramic wastewater especially in regions where POMB bottom ash is abundant.

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

PubMed Central

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

2014-01-01

Boron neutron capture therapy (BNCT) of cancer depends on the selective delivery of a sufficient number of boron-10 (10B) atoms to individual tumor cells. Cell killing results from the 10B (n, α)7Li neutron capture and fission reactions that occur if a sufficient number of 10B atoms are localized in the tumor cells. Intranuclear 10B localization enhances the efficiency of cell killing via damage to the DNA. The net cellular content of 10B atoms reflects both bound and free pools of boron in individual tumor cells. The assessment of these pools, delivered by a boron delivery agent, currently cannot be made at subcellular scale resolution by clinically applicable techniques such as PET and MRI. In this study, secondary ion mass spectrometry (SIMS) based imaging instrument, a CAMECA IMS 3f ion microscope, capable of 500 nm spatial resolution was employed. Cryogenically prepared cultured human T98G glioblastoma cells were evaluated for boron uptake and retention of two delivery agents. The first, L-p-boronophenylalanine (BPA), has been used clinically for BNCT of high grade gliomas, recurrent tumors of the head and neck region and melanomas. The second, a boron analogue of an unnatural amino acid, 1-amino-3-borono-cyclopentanecarboxylic acid (cis-ABCPC), has been studied in rodent glioma and melanoma models by quantification of boron in the nucleus and cytoplasm of individual tumor cells. The bound and free pools of boron were assessed by exposure of cells to boron-free nutrient medium. Both BPA and cis-ABCPC delivered almost 70% of the pool of boron in the free or loosely bound form to the nucleus and cytoplasm of human glioblastoma cells. This free pool of boron could be easily mobilized out of the cell and was in some sort of equilibrium with extracellular boron. In the case of BPA, the intracellular free pool of boron also was affected by the presence of phenylalanine in the nutrient medium. This suggests that it might be advantageous if patients were placed on a low phenylalanine diet prior to the initiation of BNCT. Since BPA currently is used clinically for BNCT, our observations may have direct relevance to future clinical studies utilizing this agent and provides support for individualized treatment planning regimens rather than the use of fixed BPA infusion protocols. PMID:24684609

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

PubMed

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

2014-06-01

Boron neutron capture therapy (BNCT) of cancer depends on the selective delivery of a sufficient number of boron-10 ((10)B) atoms to individual tumour cells. Cell killing results from the (10)B (n, α)(7) Li neutron capture and fission reactions that occur if a sufficient number of (10)B atoms are localized in the tumour cells. Intranuclear (10)B localization enhances the efficiency of cell killing via damage to the DNA. The net cellular content of (10)B atoms reflects both bound and free pools of boron in individual tumour cells. The assessment of these pools, delivered by a boron delivery agent, currently cannot be made at subcellular-scale resolution by clinically applicable techniques such as positron emission tomography and magnetic resonance imaging. In this study, a secondary ion mass spectrometry based imaging instrument, a CAMECA IMS 3f ion microscope, capable of 500 nm spatial resolution was employed. Cryogenically prepared cultured human T98G glioblastoma cells were evaluated for boron uptake and retention of two delivery agents. The first, L-p-boronophenylalanine (BPA), has been used clinically for BNCT of high-grade gliomas, recurrent tumours of the head and neck region and melanomas. The second, a boron analogue of an unnatural amino acid, 1-amino-3-borono-cyclopentanecarboxylic acid (cis-ABCPC), has been studied in rodent glioma and melanoma models by quantification of boron in the nucleus and cytoplasm of individual tumour cells. The bound and free pools of boron were assessed by exposure of cells to boron-free nutrient medium. Both BPA and cis-ABCPC delivered almost 70% of the pool of boron in the free or loosely bound form to the nucleus and cytoplasm of human glioblastoma cells. This free pool of boron could be easily mobilized out of the cell and was in some sort of equilibrium with extracellular boron. In the case of BPA, the intracellular free pool of boron also was affected by the presence of phenylalanine in the nutrient medium. This suggests that it might be advantageous if patients were placed on a low phenylalanine diet prior to the initiation of BNCT. Since BPA currently is used clinically for BNCT, our observations may have direct relevance to future clinical studies utilizing this agent and provides support for individualized treatment planning regimens rather than the use of fixed BPA infusion protocols. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Antioxidant responses of chickpea plants subjected to boron toxicity.

PubMed

Ardic, M; Sekmen, A H; Tokur, S; Ozdemir, F; Turkan, I

2009-05-01

This study investigated oxidative stress and the antioxidant response to boron (B) of chickpea cultivars differing in their tolerance to drought. Three-week-old chickpea seedlings were subjected to 0.05 (control), 1.6 or 6.4 mm B in the form of boric acid (H(3)BO(3)) for 7 days. At the end of the treatment period, shoot length, dry weight, chlorophyll fluorescence, B concentration, malondialdehyte content and the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) were measured. The 1.6 mm B treatment did not cause significant changes in shoot length of cultivars, although shoot length increased in the drought-tolerant Gökce and decreased in the drought-sensitive Küsmen after 6.4 mm B treatment. Dry weights of both cultivars decreased with 6.4 mm B treatment. Chlorophyll fluorescence (Fv/Fm) did not change in Gökce at either B level. Nor did it change in Küsmen with 1.6 mm B but Fv/Fm decreased with 6.4 mm B. Boron concentration in the shoots of both cultivars increased significantly with increasing levels of applied B. Significant increases in total SOD activity were observed in shoots of both cultivars given 1.6 and 6.4 mm B. Shoot extracts exhibited five activity bands, two of which were identified as MnSOD and Cu/ZnSOD. In comparison to the control group, all enzyme activities (except APX and SOD) decreased with 1.6 mm B stress. GR activity decreased, while activities of CAT, POX and APX did not change with 6.4 mm B in Küsmen. On the other hand, activities of CAT, APX and SOD increased in Gökce at both B levels. In addition, lipid peroxidation was higher in Küsmen than in Gökce, indicating more damage by B to membrane lipids in the former cultivar. These results suggest that (i) Gökce is tolerant and Küsmen is sensitive to B, and (ii) B tolerance of Gökce might be closely related to increased capacity of the antioxidative system (total SOD, CAT and APX) to scavenge reactive oxygen species and thus suppress lipid peroxidation under B stress. To the best of our knowledge, this is the first report on the antioxidant response of chickpea seedlings to B toxicity.

Development and construction of a neutron beam line for accelerator-based boron neutron capture synovectomy.

PubMed

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

2000-01-01

A potential application of the 10B(n, alpha)7Li nuclear reaction for the treatment of rheumatoid arthritis, termed Boron Neutron Capture Synovectomy (BNCS), is under investigation. In an arthritic joint, the synovial lining becomes inflamed and is a source of great pain and discomfort for the afflicted patient. The goal of BNCS is to ablate the synovium, thereby eliminating the symptoms of the arthritis. A BNCS treatment would consist of an intra-articular injection of boron followed by neutron irradiation of the joint. Monte Carlo radiation transport calculations have been used to develop an accelerator-based epithermal neutron beam line for BNCS treatments. The model includes a moderator/reflector assembly, neutron producing target, target cooling system, and arthritic joint phantom. Single and parallel opposed beam irradiations have been modeled for the human knee, human finger, and rabbit knee joints. Additional reflectors, placed to the side and back of the joint, have been added to the model and have been shown to improve treatment times and skin doses by about a factor of 2. Several neutron-producing charged particle reactions have been examined for BNCS, including the 9Be(p,n) reaction at proton energies of 4 and 3.7 MeV, the 9Be(d,n) reaction at deuteron energies of 1.5 and 2.6 MeV, and the 7Li(p,n) reaction at a proton energy of 2.5 MeV. For an accelerator beam current of 1 mA and synovial boron uptake of 1000 ppm, the time to deliver a therapy dose of 10,000 RBEcGy ranges from 3 to 48 min, depending on the treated joint and the neutron producing charged particle reaction. The whole-body effective dose that a human would incur during a knee treatment has been estimated to be 3.6 rem or 0.75 rem, for 1000 ppm or 19,000 ppm synovial boron uptake, respectively, although the shielding configuration has not yet been optimized. The Monte Carlo design process culminated in the construction, installation, and testing of a dedicated BNCS beam line on the high-current tandem electrostatic accelerator at the Laboratory for Accelerator Beam Applications at the Massachusetts Institute of Technology.

Boron and Nitrogen Codoped Carbon Layers of LiFePO4 Improve the High-Rate Electrochemical Performance for Lithium Ion Batteries.

PubMed

Zhang, Jinli; Nie, Ning; Liu, Yuanyuan; Wang, Jiao; Yu, Feng; Gu, Junjie; Li, Wei

2015-09-16

An evolutionary composite of LiFePO4 with nitrogen and boron codoped carbon layers was prepared by processing hydrothermal-synthesized LiFePO4. This novel codoping method is successfully applied to LiFePO4 for commercial use, and it achieved excellent electrochemical performance. The electrochemical performance can be improved through single nitrogen doping (LiFePO4/C-N) or boron doping (LiFePO4/C-B). When modifying the LiFePO4/C-B with nitrogen (to synthesis LiFePO4/C-B+N) the undesired nonconducting N-B configurations (190.1 and 397.9 eV) are generated. This decreases the electronic conductivity from 2.56×10(-2) to 1.30×10(-2) S cm(-1) resulting in weak electrochemical performance. Nevertheless, using the opposite order to decorate LiFePO4/C-N with boron (to obtain LiFePO4/C-N+B) not only eliminates the nonconducting N-B impurity, but also promotes the conductive C-N (398.3, 400.3, and 401.1 eV) and C-B (189.5 eV) configurations-this markedly improves the electronic conductivity to 1.36×10(-1) S cm(-1). Meanwhile the positive doping strategy leads to synergistic electrochemical activity distinctly compared with single N- or B-doped materials (even much better than their sum capacity at 20 C). Moreover, due to the electron and hole-type carriers donated by nitrogen and boron atoms, the N+B codoped carbon coating tremendously enhances the electrochemical property: at the rate of 20 C, the codoped sample can elevate the discharge capacity of LFP/C from 101.1 mAh g(-1) to 121.6 mAh g(-1), and the codoped product based on commercial LiFePO4/C shows a discharge capacity of 78.4 mAh g(-1) rather than 48.1 mAh g(-1). Nevertheless, the B+N codoped sample decreases the discharge capacity of LFP/C from 101.1 mAh g(-1) to 95.4 mAh g(-1), while the commercial LFP/C changes from 48.1 mAh g(-1) to 40.6 mAh g(-1).