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1

Radioisotope Production.  

National Technical Information Service (NTIS)

The types of nuclear reactions for radioisotope production using nuclear reactors and cyclotrons are described. The question of purity and quality control of the products are discussed. (Atomindex citation 19:051075)

C. P. G. Silva

1987-01-01

2

Cyclotron Production of Medical Radioisotopes  

NASA Astrophysics Data System (ADS)

The cyclotron production of radioisotopes for medical applications is gaining increased significance in diagnostic molecular imaging techniques such as PET and SPECT. In this regard, radioisotope production has never been easier or more convenient until de introduction of compact medical cyclotrons in the last few decades, which allowed the use of short-lived radioisotopes in in vivo nuclear medicine studies on a routine basis. This review outlines some general considerations about the production of radioisotopes using charged particle accelerators.

Ávila-Rodríguez, M. A.; Zárate-Morales, A.; Flores-Moreno, A.

2010-08-01

3

Cyclotron Production of Medical Radioisotopes  

SciTech Connect

The cyclotron production of radioisotopes for medical applications is gaining increased significance in diagnostic molecular imaging techniques such as PET and SPECT. In this regard, radioisotope production has never been easier or more convenient until de introduction of compact medical cyclotrons in the last few decades, which allowed the use of short-lived radioisotopes in in vivo nuclear medicine studies on a routine basis. This review outlines some general considerations about the production of radioisotopes using charged particle accelerators.

Avila-Rodriguez, M. A.; Zarate-Morales, A.; Flores-Moreno, A. [Unidad PET/CT-Ciclotron, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Edificio de Investigacion P.B, Cd. Universitaria, Circ. Interior, C.P. 04510 Mexico D.F. (Mexico)

2010-08-04

4

Radioisotope production targets and modules  

NASA Astrophysics Data System (ADS)

We have experienced the need to supply full radioisotope production systems that incorporate the accelerator, the beam lines, the targets and the radiochemistry in a unified package. The key component improvements are higher beam currents, more robust production targets, and efficient radiosynthesis modules. This note describes the progress we have made to produce efficient, high yield systems.

Johnson, R. R.; Erdman, K.; Gyles, W.; Burbee, J.; Manegoda, A.; Sabaiduc, V.; Kovac, B.; VanLier, E.; Wong, J.; Watt, R.; Wilson, J.; Zyuzin, A.

2005-12-01

5

BEST medical radioisotope production cyclotrons  

NASA Astrophysics Data System (ADS)

Best Cyclotron Systems Inc (BCSI) is currently developing 14 MeV, 25 MeV, 35MeV and 70MeV cyclotrons for radioisotope production and research applications as well as the entire spectrum of targets and nuclear synthesis modules for the production of Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and radiation therapy isotopes. The company is a subsidiary of Best Medical International, renowned in the field of medical instrumentation and radiation therapy. All cyclotrons have external negative hydrogen ion sources, four radial sectors with two dees in opposite valleys, cryogenic vacuum system and simultaneous beam extraction on opposite lines. The beam intensity ranges from 400 ?A to 1000 ?A, depending on the cyclotron energy and application [1].

Sabaiduc, Vasile; Milton, Bruce; Suthanthiran, Krishnan; Gelbart, W. Z.; Johnson, Richard R.

2013-04-01

6

BEST medical radioisotope production cyclotrons  

SciTech Connect

Best Cyclotron Systems Inc (BCSI) is currently developing 14 MeV, 25 MeV, 35MeV and 70MeV cyclotrons for radioisotope production and research applications as well as the entire spectrum of targets and nuclear synthesis modules for the production of Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and radiation therapy isotopes. The company is a subsidiary of Best Medical International, renowned in the field of medical instrumentation and radiation therapy. All cyclotrons have external negative hydrogen ion sources, four radial sectors with two dees in opposite valleys, cryogenic vacuum system and simultaneous beam extraction on opposite lines. The beam intensity ranges from 400 {mu}A to 1000 {mu}A, depending on the cyclotron energy and application.

Sabaiduc, Vasile; Milton, Bruce; Suthanthiran, Krishnan; Johnson, Richard R. [Best Cyclotron Systems Inc., 7-8765 Ash Street, Vancouver, British Columbia, V6P 6T3 (Canada); Gelbart, W. Z. [Advanced System Designs Inc., 5295 Bear Bay Road, Garden Bay, BC, V0N 1S1 (Canada)

2013-04-19

7

Radioisotope Production for Medical and Physics Applications  

NASA Astrophysics Data System (ADS)

Radioisotopes are critical to the science and technology base of the US. Discoveries and applications made as a result of the availability of radioisotopes span widely from medicine, biology, physics, chemistry and homeland security. The clinical use of radioisotopes for medical diagnosis is the largest sector of use, with about 16 million procedures a year in the US. The use of ^99Mo/^99mTc generator and ^18F make up the majority, but ^201Tl, ^123I, ^111In, and ^67Ga are also used routinely to perform imaging of organ function. Application of radioisotopes for therapy is dominated by use of ^131I for thyroid malignancies, ^90Y for some solid tumors, and ^89Sr for bone cancer, but production of several more exotic species such as ^225Ac and ^211At are of significant current research interest. In physics ^225Ra is of interest for CP violation studies, and the actinides ^242Am, ^249Bk, and ^254Es are needed as targets for experiments to create superheavy elements. Large amounts of ^252Cf are needed as a fission source for the CARIBU experiment at ANL. The process of radioisotope production is multidisciplinary. Nuclear physics input based on nuclear reaction excitation function data is needed to choose an optimum target/projectile in order to maximize desired isotope production and minimize unwanted byproducts. Mechanical engineering is needed to address issues of target heating, induced mechanical stress and material compatibility of target and claddings. Radiochemists are involved as well since chemical separation to purify the desired final radioisotope product from the bulk target and impurities is also usually necessary. Most neutron rich species are produced at a few government and university reactors. Other radioisotopes are produced in cyclotrons in the commercial sector, university/hospital based facilities, and larger devices at the DOE labs. The landscape of US facilities, the techniques involved, and current supply challenges will be reviewed.

Mausner, Leonard

2012-10-01

8

Alternate Applications of Fusion - Production of Radioisotopes  

SciTech Connect

A major effort to find near-term, non-electric applications of fusion energy has shown that the production of radioisotopes is attractive. The use of the D{sup 3}He fusion reaction to produce Positron Emission Tomography (PET) isotopes is described. An Inertial Electrostatic Confinement (IEC) device is particularly well suited to produce low levels of high-energy (14.7 MeV) protons, which in turn, can produce short-lived PET isotopes. The IEC device at University of Wisconsin has been modified to investigate the potential of this process to be commercially attractive.

Kulcinski, G.L.; Weidner, J.; Cipiti, B.; Ashley, R.P.; Santarius, J.F.; Murali, S.K.; Piefer, G.; Radel, R. [University of Wisconsin-Madison (United States)

2003-09-15

9

Radioisotope production at the Kazakhstan cyclotron  

Microsoft Academic Search

Cyclotrons play an important role for production of carrier-free radioisotopes for various applications in the nuclear medicine, industry, ecology and science. Kazakhstan variable energy isochronous cyclotron, K = 50 MeV, is a 150 cm compact-pole 3 sector positive ion machine. It generates different beams of light ions: protons 6-30 MeV, deuterons 12.5-25 MeV, 3He-ions 18.5-62 MeV, alpha-particles 25-50 MeV. In

A. Arzumanov; V. Batischev; N. Berdinova; A. Borissenko; G. Chumikov; N. Gorodisskaya; A. Knyazev; V. Koptev; S. Lyssukhin; Yu. Popov; G. Sychikov; D. Zheltov

2003-01-01

10

H Exp - Cyclotrons for Radioisotope Production.  

National Technical Information Service (NTIS)

Over the past few years H exp - cyclotrons have been introduced as powerful radioisotope producers. Four of these machines, supplied by The Cyclotron Corporation of Berkeley, California, are now in regular operation in the US, Britain, Germany and Canada....

J. J. Burgerjon

1984-01-01

11

Radioisotope production and management at Oak Ridge National Laboratory  

SciTech Connect

The production of radioisotopes has been one of the basic activities at Oak Ridge since the end of World War II. The importance of this work was best described by Alvin Weinberg, former Laboratory Director, when he wrote ``... If God has a golden book and writes down what it is that Oak Ridge National Laboratory did that had the biggest influence on science, I would guess that was the production and distribution of isotopes.`` Radioisotopes production continues to be an important aspect of Oak Ridge programs today and of those planned for the future. Past activities, current projects, and future plans and potentials will be described briefly in this paper. Also, some of the major issues facing the continued production of radioisotopes will be described. The scope of the program has always been primarily that of process development, followed by special batch-type productions, where no other supply exists. The technology developed has been available for adoption by US commercial corporations, and in cases where this has occurred, Oak Ridge has withdrawn as a supplier of the particular isotopes involved. One method of production that will not be described is that of target bombardment with an accelerator. This method was used at Oak Ridge prior to 1978 in the 86-inch Cyclotron. However, this method has not been used at Oak Ridge since then for radioisotope production, except as a research tool.

Collins, E.D.; Aaron, W.S.; Alexander, C.W.; Bigelow, J.E.; Parks, J.T.; Tracy, J.G.; Wham, R.M.

1994-09-01

12

Optimization of commercial scale photonuclear production of radioisotopes  

SciTech Connect

Photonuclear production of radioisotopes driven by bremsstrahlung photons using a linear electron accelerator in the suitable energy range is a promising method for producing radioisotopes. The photonuclear production method is capable of making radioisotopes more conveniently, cheaply and with much less radioactive waste compared to existing methods. Historically, photo-nuclear reactions have not been exploited for isotope production because of the low specific activity that is generally associated with this production process, although the technique is well-known to be capable of producing large quantities of certain radioisotopes. We describe an optimization technique for a set of parameters to maximize specific activity of the final product. This set includes the electron beam energy and current, the end station design (an integrated converter and target as well as cooling system), the purity of materials used, and the activation time. These parameters are mutually dependent and thus their optimization is not trivial. {sup 67}Cu photonuclear production via {sup 68}Zn({gamma}p){sup 67}Cu reaction was used as an example of such an optimization process.

Bindu, K. C.; Harmon, Frank; Starovoitova, Valeriia N.; Stoner, Jon; Wells, Douglas P. [Idaho Accelerator Center, Idaho State University, 1500 Alvin Ricken Drive, Pocatello, ID 83201 (United States)

2013-04-19

13

A novel superconducting cyclotron for therapy and radioisotope production  

NASA Astrophysics Data System (ADS)

The design of a four sector compact superconducting cyclotron, able to accelerate up to 250 A MeV light ions with charge/mass ratio 0.5, is in progress. Light ions like 12C 6+, 10B 5+, 6Li 3+ will be extracted by electrostatic deflectors while H 2+ ions can be extracted also by stripping, therefore a beam power of 10 kW or more is available. This cyclotron can be used for radiotherapy with protons or carbon ions and also to drive a facility for production of unusual medical radioisotopes. The main parameters and some features of the machine are here presented.

Calabretta, Luciano; Cuttone, Giacomo; Maggiore, Mario; Re, Maurizio; Rifuggiato, Danilo

2006-06-01

14

Reactor production and processing of radioisotopes for therapeutic applications in nuclear medicine  

SciTech Connect

Nuclear reactors continue to play an important role in providing radioisotopes for nuclear medicine. Many reactor-produced radioisotopes are ``neutron rich`` and decay by beta-emission and are thus of interest for therapeutic applications. This talk discusses the production and processing of a variety of reactor-produced radioisotopes of current interest, including those produced by the single neutron capture process, double neutron capture and those available from beta-decay of reactorproduced radioisotopes. Generators prepared from reactorproduced radioisotopes are of particular interest since repeated elution inexpensively provides many patient doses. The development of the alumina-based W-188/Re-188 generator system is discussed in detail.

Knapp, F.F. Jr.; Mirzadeh, S.; Beets, A.L.

1995-02-01

15

Novel production techniques of radioisotopes using electron accelerators  

NASA Astrophysics Data System (ADS)

Non-traditional radioisotope production techniques using a compact, high power linear electron accelerator have been demonstrated and characterized for the production of 18F, 47Sc, 147 Pm, and 99mTc from a variety of target candidates. These isotopes are used extensively in the medical field as diagnostic and therapy radioisotopes, as well as the space industry as RTG's. Primary focus was placed on 99mTc as it constitutes approximately 80% of all diagnostic procedures in the medical community that use radioactive tracers. It was also the prime focus due to recent events at the Chalk River nuclear reactor, which caused global shortages of this isotope a few years ago. A Varian K15 LINAC was first used to show proof of principle in Las Vegas. Various samples were then taken to the Idaho Accelerator Center where they were activated using an electron LINAC capable of electron energies from 4 to 25 MeV at a beam power of approximately 1 kW. Production rates, cross sections, and viability studies were then performed and conducted to assess the effectiveness of the candidate target and the maximum production rate for each radioisotope. Production rates for 18F from lithium fluoride salts were shown to be ideal at 21MeV, namely 1.7 Ci per kg of LiF salt, per kW of beam current, per 10 hour irradiation time. As the typical hospital consumption of 18F is around 500 mCi per day, it is clear that a large amount of 18F can be made from a small (300 gram) sample of LiF salt. However, since there is no current separation process for 18F from 19F, the viability of this technique is limited until a separations technique is developed. Furthermore, the calculated cross section for this reaction is in good agreement with literature, which supports the techniques for the isotopes mentioned below. Production rates for 47Sc from vanadium oxide targets were shown to be a maximum at 25 MeV with a production rate of 2 mCi per day, assuming a 2 kW beam and a 10 kg target. While this production rate would be able to support a research environment where a single patient per day would be addressed, it is unlikely that this method would produce enough material to support a large hospital. The production of 147Pm from europium oxide targets showed that due to the large spin state differences between 151Eu and 147Pm, a negligible amount of 147Pm can be created using the (gamma,alpha) process. The minimum detectable limit for these experiments, given this specific isotope, was 10 nCi. The (gamma, gamma') reaction was studied on 99mTc to determine the production rates and cross sections for this reaction. It was found that the average production rate between 12 and 25 MeV was approximately 3 uCi/(kg*kW). Given that a single patient dose of 99mTc is approximately 20 mCi, we find that we need many kilograms of technetium metal. This would produce toxic levels of technetium in the patient; therefore this method is not likely viable. It was also found, however, that the (n,n') reaction may play a significant role in the activation from ground state technetium to the metastable state. Finally, the (gamma, alpha) reaction that will produce 99m Tc from rhodium oxide targets was quantified from energies of 12 to 25 MeV. The production rate was found to be 64 and 113 mCi/(kg*kW*day) for 19 and 25 MeV, respectively. Given a 2 kW beam and a 2 kg target, we find this technique to be a feasible method to create 99mTc in a local setting using a LINAC. By using a fast separations technique, such as selective volatilization, a process in which technetium oxide is volatilized off of rhodium oxide in a carrier gas could provide a turn-key solution for entities looking to create this radioisotope on site. A cost-benefit analysis was performed and it was found that a system such as this could produce over $1M in revenue per year given a standard hospital usage of 40 patient doses per day.

Lowe, Daniel Robert

16

Boron modified molybdenum silicide and products  

DOEpatents

A boron-modified molybdenum silicide material having the composition comprising about 80 to about 90 weight % Mo, about 10 to about 20 weight % Si, and about 0.1 to about 2 weight % B and a multiphase microstructure including Mo.sub.5 Si.sub.3 phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum silicide material is fabricated into such products as electrical components, such as resistors and interconnects, that exhibit oxidation resistance to withstand high temperatures in service in air as a result of electrical power dissipation, electrical resistance heating elements that can withstand high temperatures in service in air and other oxygen-bearing atmospheres and can span greater distances than MoSi.sub.2 heating elements due to improved creep resistance, and high temperature structural members and other fabricated components that can withstand high temperatures in service in air or other oxygen-bearing atmospheres while retaining creep resistance associated with Mo.sub.5 Si.sub.3 for structural integrity.

Meyer, Mitchell K. (Idaho Falls, ID); Akinc, Mufit (Ames, IA)

1999-02-02

17

Preliminary investigation of parasitic radioisotope production using the LANL IPF secondary neutron flux  

NASA Astrophysics Data System (ADS)

In order to ascertain the potential for radioisotope production and material science studies using the Isotope Production Facility at Los Alamos National Lab, a two-pronged investigation has been initiated. The Monte Carlo for Neutral Particles eXtended (MCNPX) code has been used in conjunction with the CINDER 90 burnup code to predict neutron flux energy distributions as a result of routine irradiations and to estimate yields of radioisotopes of interest for hypothetical irradiation conditions. A threshold foil activation experiment is planned to study the neutron flux using measured yields of radioisotopes, quantified by HPGe gamma spectroscopy, from representative nuclear reactions with known thresholds up to 50 MeV.

Engle, J. W.; Kelsey, C. T.; Bach, H.; Ballard, B. D.; Fassbender, M. E.; John, K. D.; Birnbaum, E. R.; Nortier, F. M.

2012-12-01

18

Potential medical applications of the plasma focus in the radioisotope production for PET imaging  

NASA Astrophysics Data System (ADS)

Devices other than the accelerators are desired to be investigated for generating high energy particles to induce nuclear reaction and positron emission tomography (PET) producing radioisotopes. The experimental data of plasma focus devices (PF) are studied and the activity scaling law for External Solid Target (EST) activation is established. Based on the scaling law and the techniques to enhance the radioisotopes production, the feasibility of generating the required activity for PET imaging is studied.

Roshan, M. V.; Razaghi, S.; Asghari, F.; Rawat, R. S.; Springham, S. V.; Lee, P.; Lee, S.; Tan, T. L.

2014-06-01

19

A Multilevel Automation Concept for the Target-Based Production of Radioisotopes for Cancer Treatment  

Microsoft Academic Search

Alpha-particle-immuno-therapy is a new approach for the treatment of cancer. To produce the required radioisotope actinium (Ac-225) and thus enable the new therapy, an automated manufacturing plant needs to be developed. A striking characteristic of this project is the usage of the long-lived radioisotope radium (Ra-226) as source of the production, meaning that from the very beginning, radioactive material has

A. Eursch; M. Harfensteller; M. Schilp; M. F. Zaeh; J. Moreno; E. Kabai

2006-01-01

20

Production of industrial and medical radioisotopes in accelerator production of tritium  

NASA Astrophysics Data System (ADS)

The accelerator production of tritium (APT) has attained an interested in radioisotope production. The unique design of APT would deliver the most powerful and high- energy beam of protons with 170 MW beam power and 1.7 GeV beam energy, to a target for radionuclide production. The production rate for each reaction has been calculated using the MCNPX codes. The reaction cross section for this study has been generated using the LAHET, MCNP4B and HTAPE codes. The generated cross sections were compared with the experimental cross sections. The double-wall tubes with 2 cm-diameter and 200.cm-height were inserted 3 cm behind 13 tungsten neutron source ladders in APT. Radioisotope production was analyzed to determine the radiopurity and production rate in 13 double wall tubes. The results show that the neutron and proton fluxes were greatest in the middle segment and decreasing towards the top and the bottom of the tubes. Therefore, the middle segment was used for presentation of the radioisotope production. The highest neutron flux is 7.88 × 10 14 +/- 0.56% in the middle segment of a tube behind fifth ladder. The highest proton flux is 1.65 × 1014 +/- 0.76%, obtained from the middle segment of a tube behind first ladder. The successive decay differential equation calculation was used to account for time dependent effects because the MCNPX code does not integrate time dependent behavior. In these calculations, the neutron flux level and spectra are assumed to remain constant over the irradiation period. Some examples 72As, 128Ba, 7Be, 139Ce, 56Co, 18F, 111In, 103Pd and 48V. The example of radionuclides by neutron reaction includes 74As, 14C, 60Co, 165Dy, 18F, 99Mo, 33P, 35S, 99mTc, 117Sn, and 65Zn. The results show that high production rate and high radiopurity of several radioisotopes can be achieved using high-energy neutron and proton fluxes from APT. A comparison of the production yield for some radionuclides (32P and 67Cu) using CINDER'90 between this study and preliminary calculations from LANL shows that the deviation is within 6.4% to 7.6%. The calculation method used in this study specifically for APT target design can also be applied to any other accelerator design.

Tiyapun, Kanokrat

2000-11-01

21

An alternate approach to the production of radioisotopes for nuclear medicine applications  

NASA Astrophysics Data System (ADS)

There is a growing need for the production of radioisotopes for both diagnostic and therapeutic medical applications. Radioisotopes that are produced using the (n,?) or (?,n) reactions, however, typically result in samples with low specific activity (radioactivity/gram) due to the high abundance of target material of the same element. One method to effectively remove the isotopic impurity is electro-magnetic mass separation. An Ion Source Test Facility has been constructed at TRIUMF to develop high-intensity, high-efficiency, reliable ion sources for purification of radioactive isotopes, particularly those used in nuclear medicine. In progress studies are presented.

D'Auria, John M.; Keller, Roderich; Ladouceur, Keith; Lapi, Suzanne E.; Ruth, Thomas J.; Schmor, Paul

2013-03-01

22

Production of stripper foils by laser ablation of carbon-boron sputter targets  

NASA Astrophysics Data System (ADS)

The TRIUMF Applied Technology Group operates several high-power industrial cyclotrons for commercial radioisotope production. Two of these accelerators, TR30-1 and TR30-2, can deliver H - beams of 30 MeV and beam currents in excess of 1000 ?A. For many years, in-house produced diamond-like carbon (DLC) foils of approximately 2.0-3.0 ?m thickness have been utilized to extract proton beams from these accelerators. The TRIUMF Carbon Foil Laboratory uses pulsed laser deposition to manufacture DLC films in a wide thickness range (10 nm to ˜10 ?m). It is known that the quality and the composition of the graphite sputter target used in the laser ablation process has a significant effect on the mechanical properties of the deposited film as well as its durability in ion beams. Encouraged by the findings of Sugai et al. [1], we investigated the production of stripper foils by laser ablation of graphite/boron composites as well as multilayer foils using pure graphite and boron targets.

Zeisler, Stefan K.; Jaggi, Vinder

2010-02-01

23

A proton-driven, intense, subcritical, fission neutron source for radioisotope production  

Microsoft Academic Search

99mTc, the most frequently used radioisotope in nuclear medicine, is distributed as 99Mo&squflg;99mTc generators. 99Mo is a fission product of 235U. To replace the aging nuclear reactors used today for this production, we propose to use a spallation neutron source, with neutron multiplication by fission. A 150 MeV, H? cyclotron can produce a 225 kW proton beam with 50% total

Yves Jongen; Yves

1995-01-01

24

Production and supply of radioisotopes with high-energy particle accelerators current status and future directions  

SciTech Connect

Although the production of radioisotopes in reactors or in low to medium energy cyclotrons appears to be relatively well established, especially for those isotopes that are routinely used and have a commercial market, certain isotopes can either be made only in high-energy particle accelerators or their production is more cost effective when made this way. These facilities are extremely expensive to build and operate, and isotope production is, in general, either not cost-effective or is in conflict with their primary mandate or missions which involve physics research. Isotope production using high-energy accelerators in the US, therefore, has been only an intermittent and parasitic activity. However, since a number of isotopes produced at higher energies are emerging as being potentially useful for medical and other applications, there is a renewed concern about their availability in a continuous and reliable fashion. In the US, in particular, the various aspects of the prediction and availability of radioisotopes from high-energy accelerators are presently undergoing a detailed scrutiny and review by various scientific and professional organizations as well as the Government. A number of new factors has complicated the supply/demand equation. These include considerations of cost versus needs, reliability factors, mission orientation, research and educational components, and commercial viability. This paper will focus on the present status and projected needs of radioisotope production with high-energy accelerators in the US, and will compare and examine the existing infrastructure in other countries for this purpose.

Srivastava, S.C.; Mausner, L.F.

1994-03-01

25

Student research with 400keV beams: {sup 13}N radioisotope production target development  

SciTech Connect

The AN400 Van de Graaff accelerator at the Minnesota State University, Mankato, Applied Nuclear Science Lab has demonstrated utility as an accessible and versatile platform for student research. Despite the limits of low energy, the research team successfully developed projects with applications to the wider radioisotope production community. A target system has been developed for producing and extracting {sup 13}N by the {sup 12}C(d,n){sup 13}N reaction below 400keV. The system is both reusable and robust, with future applications to higher energy machines producing this important radioisotope for physiological imaging studies with Positron Emission Tomography. Up to 36({+-}1)% of the {sup 13}N was extracted from the graphite matrix when 35 A current was externally applied to the graphite target while simultaneously flushing the target chamber with CO{sub 2} gas.

Fru, L. Che; Clymer, J.; Compton, N.; Cotter, J.; Dam, H.; Lesko, Z.; Pautzke, J.; Prokop, C.; Swanson, L.; Roberts, A. D. [Department of Physics and Astronomy, Minnesota State University, Trafton Science Center N141, Mankato MN 56001 (United States)

2013-04-19

26

Production of ^38K Radioisotope for Plant Research  

NASA Astrophysics Data System (ADS)

Identifying and measuring the time scale of physiological responses to environmental changes provides information about mechanisms involved in the resource regulatory system of plants. Varying the amounts and types of nutrients and minerals available to a plant, the uptake and allocation of these resources are observed using Positron Emission Tomography (PET). Potassium is important to plant growth and maintenance in a number of areas. Among them is the K^+ and H^+ ion exchange provides the driving force for sugar loading into the phloem. A technique was developed for producing ^38K in a chemical form that can be absorbed by plants. The ^38K was created by the ^35Cl(?,n)^38K reaction using 14 MeV ?-particles from the tandem accelerator at the Triangle Universities Nuclear Laboratory (TUNL). The target was a NaCl film about 20 mg/cm^2 thick that was evaporated onto a water-cooled tantalum disk. The irradiated NaCl film was dissolved in water and was transported to the Duke Plant Facilities (The Phytotron). The details of isotope production and demonstration of plant physiology measurement are presented.

Zawisza, Irene; Howell, C. R.; Crowell, A. S.; Reid, C. D.; Weisenberger, D.

2012-10-01

27

Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production  

NASA Astrophysics Data System (ADS)

To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor).

Liem, Peng Hong; Tran, Hoai Nam; Sembiring, Tagor Malem; Arbie, Bakri

2014-09-01

28

Hospital-based proton linear accelerator for particle therapy and radioisotope production  

NASA Astrophysics Data System (ADS)

Taking advantage of recent advances in linear accelerator technology, it is possible for a hospital to use a 70 MeV proton linac for fast neutron therapy, boron neutron capture therapy, proton therapy for ocular melanomas, and production of radiopharmaceuticals. The linac can also inject protons into a synchrotron for proton therapy of deep-seated tumors. With 180 ?A average current, a single linac can support all these applications. This paper presents a conceptual design for a medical proton linac, switchyard, treatment rooms, and isotope production rooms. Special requirements for each application are outlined and a layout for sharing beam among the applications is suggested.

Lennox, Arlene J.

1991-05-01

29

Proton linac for hospital-based fast neutron therapy and radioisotope production  

SciTech Connect

Recent developments in linac technology have led to the design of a hospital-based proton linac for fast neutron therapy. The 180 microamp average current allows beam to be diverted for radioisotope production during treatments while maintaining an acceptable dose rate. During dedicated operation, dose rates greater than 280 neutron rads per minute are achievable at depth, DMAX = 1.6 cm with source to axis distance, SAD = 190 cm. Maximum machine energy is 70 MeV and several intermediate energies are available for optimizing production of isotopes for Positron Emission Tomography and other medical applications. The linac can be used to produce a horizontal or a gantry can be added to the downstream end of the linac for conventional patient positioning. The 70 MeV protons can also be used for proton therapy for ocular melanomas. 17 refs., 1 fig., 1 tab.

Lennox, A.J.; Hendrickson, F.R.; Swenson, D.A.; Winje, R.A.; Young, D.E. (Fermi National Accelerator Lab., Batavia, IL (USA); Rush Univ., Chicago, IL (USA); Science Applications International Corp., Princeton, NJ (USA); Fermi National Accelerator Lab., Batavia, IL (USA))

1989-09-01

30

Boron  

SciTech Connect

This paper reports that borate minerals and refined borates are used extensively for the manufacture of vitreous materials such as insulation and textile fiberglasses, borosilicate glass, and porcelain enamels and frits. In North America, these applications are estimated to account for over 54% of the borate consumption. Other substantial uses are in soaps and detergents, metallurgy, fire retardants, industrial biocides, agriculture, and various miscellaneous applications. Reported domestic borate consumption in 1990 was estimated by the U.S. Bureau of Mines to be 320 000 metric tons B{sub 2}O{sub 3} versus 354 000 metric tons B{sub 2}O{sub 3} in 1989. Consumption is projected to remain essentially static in 1991. Imports were estimated by the Bureau to be 50 000 metric tons B{sub 2}O{sub 3} in 1990. Exports of boric acid and refined borates were approximately 650 000 metric tons of product, a 15 000 metric ton increase from the 1989 level. This increase partially offsets the drop in the 1990 consumption level.

Cozen, L.F. (United States Borax and Chemical Corp., Los Angeles, CA (US))

1991-05-01

31

Production of radioisotopes by 1. 5m cyclotron and their utilization  

SciTech Connect

Radioisotopes characterized by nuclear property and uses can be produced on the accelerator, especially those playing an important role in scientific researches and biomedical uses. The status of Radioisotopes produced by 1.5m cyclotron and their applications in our institute are summarized in this paper. The details of preparation and the results of use for radioactive sources, radiochemicals, radiopharmaceuticals of /sup 57/Co, /sup 109/Cd, /sup 68/Ga, and /sup 167/Tm are given respectively.

Fang, N.

1988-01-01

32

The Cyclotron radioisotopes production facility of the Argentinean Atomic Energy Commission (CNEA)  

NASA Astrophysics Data System (ADS)

A Cyclotron facility for radioisotopes production has been in operation in the Atomic Center Ezeiza since 1994. An H- 42 MeV Cyclotron, two target vaults, three hot-cells and a radiochemistry laboratory are dedicated for routinely production of 201Tl and FDG. A 123Xe target station is being currently constructed in a third target vault under an IAEA support project. The Cyclotron is a CP42 H- model, which was refurbished in Karlsruhe, Germany. This CP42 has a few added improvements, which make it one of the best of its class. The improvements included a source vacuum lock and a precise position control. The original variable energy extractor was also changed. The new one extracts the beam through another port than the original, which was selected for better beam quality for 25 MeV to 42 MeV. Recent improvements to the central region increased the internal beam available for acceleration, reaching a maximum of more than 400 ?A. An external current in excess of 200 ?A is also routinely achievable. Very high vacuum and very efficient and reliable RF system must be maintained to increase this limit. In addition, beam current limitations due to axial space charge effects in terms of vertical aperture and axial betatron frequencies will be discussed. The target systems are being improved for higher beam current. A new modern PC control software coupled to the original electronic control system will be described here. This program simplifies and fastens the operator tasks, providing also more information for diagnostics.

Strangis, S. R.; Maslat, G. J.

2001-12-01

33

Improved Techniques Used at Brookhaven National Laboratory to Package and Dispose of Radioisotope Production Waste Lowers Worker Exposure  

SciTech Connect

This paper describes the operations that generate Radioisotope Production Waste at Brookhaven National Laboratory (BNL) and the improved techniques used to handle and dispose of this waste. Historically, these wastes have produced high worker exposure during processing, packaging and disposal. The waste is made up of accelerator-produced nuclides of short to mid-length half-lives with a few longer-lived nuclides. However, because radiopharmaceutical research and treatment requires a constant supply of radioisotopes, the waste must be processed and disposed of in a timely manner. Since the waste cannot be stored for long periods of time to allow for adequate decay, engineering processes were implemented to safely handle the waste routinely and with ALARA principles in mind.

Sullivan, P.

2003-02-24

34

Operational readiness review plan for the radioisotope thermoelectric generator materials production tasks  

Microsoft Academic Search

In October 1989, a Space Shuttle lifted off from Cape Kennedy carrying the spacecraft Galileo on its mission to Jupiter. In November 1990, a second spacecraft, Ulysses, will be launched from Cape Kennedy with a mission to study the polar regions of the sun. The prime source of power for both spacecraft is a series of radioisotope thermoelectric generators (RTG's),

R. H. Cooper; M. M. Martin; C. R. Riggs; R. L. Beatty; E. K. Ohriner; R. N. Escher

1990-01-01

35

Production of medical radioisotopes with high specific activity in photonuclear reactions with ?-beams of high intensity and large brilliance  

NASA Astrophysics Data System (ADS)

We study the production of radioisotopes for nuclear medicine in ( ?, xn+ yp) photonuclear reactions or ( ?, ?') photoexcitation reactions with high-flux [(1013-1015) ?/s], small diameter ˜(100 ?m)2 and small bandwidth (? E/ E?10-3-10-4) ? beams produced by Compton back-scattering of laser light from relativistic brilliant electron beams. We compare them to (ion, xn+ yp) reactions with (ion = p,d, ?) from particle accelerators like cyclotrons and (n, ?) or (n,f) reactions from nuclear reactors. For photonuclear reactions with a narrow ?-beam the energy deposition in the target can be managed by using a stack of thin target foils or wires, hence avoiding direct stopping of the Compton and pair electrons (positrons). However, for ions with a strong atomic stopping only a fraction of less than 10-2 leads to nuclear reactions resulting in a target heating, which is at least 105 times larger per produced radioactive ion and often limits the achievable activity. In photonuclear reactions the well defined initial excitation energy of the compound nucleus leads to a small number of reaction channels and enables new combinations of target isotope and final radioisotope. The narrow bandwidth ? excitation may make use of the fine structure of the Pygmy Dipole Resonance (PDR) or fluctuations in ?-width leading to increased cross sections. Within a rather short period compared to the isotopic half-life, a target area of the order of (100 ?m)2 can be highly transmuted, resulting in a very high specific activity. ( ?, ?') isomer production via specially selected ? cascades allows to produce high specific activity in multiple excitations, where no back-pumping of the isomer to the ground state occurs. We discuss in detail many specific radioisotopes for diagnostics and therapy applications. Photonuclear reactions with ?-beams allow to produce certain radioisotopes, e.g. 47Sc, 44Ti, 67Cu, 103Pd, 117 m Sn, 169Er, 195 m Pt or 225Ac, with higher specific activity and/or more economically than with classical methods. This will open the door for completely new clinical applications of radioisotopes. For example 195 m Pt could be used to verify the patient's response to chemotherapy with platinum compounds before a complete treatment is performed. Also innovative isotopes like 47Sc, 67Cu and 225Ac could be produced for the first time in sufficient quantities for large-scale application in targeted radionuclide therapy.

Habs, D.; Köster, U.

2011-05-01

36

Boron reclamation  

SciTech Connect

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

Smith, R.M.

1980-07-01

37

High purity materials as targets for radioisotope production: Needs and challenges  

Microsoft Academic Search

Radionuclides have become powerful and indispensable tools in many endeavours of human activities, most importantly in medicine,\\u000a industry, biology and agriculture, apart from R&D activities. Ready availability of radionuclides in suitable radiochemical\\u000a form, its facile detection and elegant tracer concepts are responsible for their unprecedented use. Application of radioisotopes\\u000a in medicine has given birth to a new branch, viz. nuclear

V. Shivarudrappa; K. V. Vimalnath

2005-01-01

38

Production of medical radioisotopes in the ORNL High Flux Isotope Reactor (HFIR) for cancer treatment and arterial restenosis therapy after PTCA  

SciTech Connect

The High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) represents an important resource for the production of a wide variety of medical radioisotopes. In addition to serving as a key production site for californium-252 and other transuranic elements, important examples of therapeutic radioisotopes which are currently routinely produced in the HFIR for distribution include dysprosium-166 (parent of holmium-166), rhenium-186, tin-117m and tungsten-188 (parent of rhenium-188). The nine hydraulic tube (HT) positions in the central high flux region permit the insertion and removal of targets at any time during the operating cycle and have traditionally represented a major site for production of medical radioisotopes. To increase the irradiation capabilities of the HFIR, special target holders have recently been designed and fabricated which will be installed in the six Peripheral Target Positions (PTP), which are also located in the high flux region. These positions are only accessible during reactor refueling and will be used for long-term irradiations, such as required for the production of tin-117m and tungsten-188. Each of the PTP tubes will be capable of housing a maximum of eight HT targets, thus increasing the total maximum number of HT targets from the current nine, to a total of 57. In this paper the therapeutic use of reactor-produced radioisotopes for bone pain palliation and vascular brachytherapy and the therapeutic medical radioisotope production capabilities of the ORNL HFIR are briefly discussed.

Knapp, F.F. Jr.; Beets, A.L.; Mirzadeh, S.; Alexander, C.W.; Hobbs, R.L.

1998-06-01

39

Investigation of excitation functions of alpha induced reactions on natXe: Production of the therapeutic radioisotope 131Cs  

NASA Astrophysics Data System (ADS)

Excitation functions were measured for alpha-particle induced nuclear reactions on natural xenon leading to the formation of the radionuclides 129m(rel),129g,131m,131mg,133m,135m,137m,139cumBa and 129cum,130mg,132,134m,135m,136mg,138mgCs from the respective thresholds up to 40 MeV. No earlier experimental cross section data were found in the literature. The experimental data were compared to and analyzed with the results of the theoretical model code ALICE-IPPE. The feasibility of the production of the therapeutic radioisotope 131Cs by using gas target technology was investigated. Comparison of reactor and cyclotron production routes of 131Cs was given.

Tárkányi, F.; Hermanne, A.; Király, B.; Takács, S.; Ditrói, F.; Sonck, M.; Kovalev, S. F.; Ignatyuk, A. V.

2009-03-01

40

Masters Thesis- Criticality Alarm System Design Guide with Accompanying Alarm System Development for the Radioisotope Production Laboratory in Richland, Washington  

SciTech Connect

A detailed instructional manual was created to guide criticality safety engineers through the process of designing a criticality alarm system (CAS) for Department of Energy (DOE) hazard class 1 and 2 facilities. Regulatory and technical requirements were both addressed. A list of design tasks and technical subtasks are thoroughly analyzed to provide concise direction for how to complete the analysis. An example of the application of the design methodology, the Criticality Alarm System developed for the Radioisotope Production Laboratory (RPL) of Richland, Washington is also included. The analysis for RPL utilizes the Monte Carlo code MCNP5 for establishing detector coverage in the facility. Significant improvements to the existing CAS were made that increase the reliability, transparency, and coverage of the system.

Greenfield, Bryce A.

2009-12-20

41

Production of Lithium, Beryllium, and Boron by Hypernovae  

E-print Network

We investigate a possible nucleosynthetic signature of highly energetic explosions of C-O cores ("hypernovae," HNe) which might be associated with gamma-ray bursts (GRBs). We note that the direct impact of C- and O-enriched hypernova ejecta on the ambient hydrogen and helium leads to spallation reactions which can produce large amounts of the light nuclides lithium, beryllium, and boron (LiBeB). Using analytic velocity spectra of the hypernova ejecta, we calculate the LiBeB yields of different exploding C-O cores associated with observed hypernovae. The deduced yields are $\\sim 10^3$ times higher than those produced by similar (direct) means in normal Type II supernovae, and are higher than the commonly used ones arising from shock wave acceleration induced by Type II supernova (SN) explosions. To avoid overproduction of these elements in our Galaxy, hypernovae should be rare events, with $\\la 10^{-3}$ hypernovae per supernova, assuming a constant HN/SN ratio over time. This rate is in good agreement with that of long duration GRBs if we assume that the gamma-ray emission is focussed with a beaming factor $\\Omega/4\\pi \\la 10^{-2}$. This encouraging result supports the possible HN-GRB association. Thus, Galactic LiBeB abundance measurements offer a promising way to probe the HN rate history and the possible HN-GRB correlation. On the other hand, if hypernovae are associated to very massive pregalactic stars (Population III) they would produce a LiBeB pre-enrichment in proto-galactic gas, which could show up as a plateau in the lowest metallicities of the Be-Fe relation in halo stars.

Brian D. Fields; Frederic Daigne; Michel Casse; Elisabeth Vangioni-Flam

2001-07-25

42

Production of {sup 17}F, {sup 15}O and other radioisotopes for PET using a 3 MV electrostatic tandem accelerator  

SciTech Connect

Target systems for the production of positron emitting radioisotopes used for medical research with positron emission tomography (PET) are under development for a 3 MV electrostatic tandem accelerator (NEC 9SDH-2). This machine is intended primarily for the continuous production of short lived tracers labeled with {sup 15}O (t{sub 1/2}=122 s) or {sup 17}F (t{sub 1/2}=65 s) for determining regional cerebral blood flow in humans. Simple gas, liquid, and solid target systems are presented for the production of [{sup 15}O]H{sub 2}O (yield at saturation 13 mCi/{mu}A), [{sup 17}F]F{sub 2} (22 mCi/{mu}A), [{sup 17}F] fluoride (aq.) (12 mCi/{mu}A), [{sup 18}F]fluoride (aq.) (21 mCi/{mu}A), [{sup 13}N] in graphite (25 mCi/{mu}A), and [{sup 11}C]CO{sub 2} (2.3 mCi/{mu}A). Current limitations on single window targets for each production are discussed.

Roberts, A. D. [Medical Physics Department, University of Wisconsin, Madison, Wisconsin 53706 (United States); Psychology Department, University of Wisconsin, Madison, Wisconsin 53706 (United States); Davidson, R. J. [Psychology Department, University of Wisconsin, Madison, Wisconsin 53706 (United States); Nickles, R. J. [Medical Physics Department, University of Wisconsin, Madison, Wisconsin 53706 (United States)

1999-06-10

43

The Spallagenic Production Rates of Lithium, Beryllium and Boron  

E-print Network

We calculate the production rates of Li6, Li7, Be9, B10 and B11 via spallation of Carbon, Nitrogen and Oxygen nuclei by protons and alpha-particles and by alpha-alpha fusion reactions. We include recent measurements of the cross sections of alpha-alpha fusion reactions and find that the computations yield rates of Li6 and Li7 production that are nearly a factor of two smaller than previously calculated. We begin by using the `straight ahead' approximation for the fragment energy and the `leaky-box' model for product capture in the Galaxy. In addition we test the straight ahead approximation by recalculating the production rates using an empirical description of the fragment energy distribution and find that the results closely match. We have also calculated the rates for various cosmic ray spectra and find that the hardest spectra tested decrease the rates with CR CNO by approximately an order of magnitude relative to our chosen standard. Finally we have computed the Population I elemental ratios and the Population II scaling relations for our standard and find that our computations predict an abundance of Lithium for a given abundance of Beryllium that is 1/4 smaller than previously derived.

J. P. Kneller; J. R. Phillips; T. P. Walker

2000-08-04

44

Cosmic Ray production of Beryllium and Boron at high redshift  

E-print Network

Recently, new observations of Li6 in Pop II stars of the galactic halo have shown a surprisingly high abundance of this isotope, about a thousand times higher than its predicted primordial value. In previous papers, a cosmological model for the cosmic ray-induced production of this isotope in the IGM has been developed to explain the observed abundance at low metallicity. In this paper, given this constraint on the Li6, we calculate the non-thermal evolution with redshift of D, Be, and B in the IGM. In addition to cosmological cosmic ray interactions in the IGM, we include additional processes driven by SN explosions: neutrino spallation and a low energy component in the structures ejected by outflows to the IGM. We take into account CNO CRs impinging on the intergalactic gas. Although subdominant in the galactic disk, this process is shown to produce the bulk of Be and B in the IGM, due to the differential metal enrichment between structures (where CRs originate) and the IGM. We also consider the resulting extragalactic gamma-ray background which we find to be well below existing data. The computation is performed in the framework of hierarchical structure formation considering several star formation histories including Pop III stars. We find that D production is negligible and that a potentially detectable Be and B plateau is produced by these processes at the time of the formation of the Galaxy (z ~ 3).

Emmanuel Rollinde; David Maurin; Elisabeth Vangioni; Keith A. Olive; Susumu Inoue

2007-07-13

45

Five Years of Cyclotron Radioisotope Production Experiences at the First PET-CT in Venezuela  

NASA Astrophysics Data System (ADS)

Five years operation of a compact cyclotron installed at PET-CT facility in Caracas, Venezuela is given. Production rate of 18F labeled FDG, operation and radiation monitoring experience are included. We conclude that 18FDG CT-PET is the most effective technique for patient diagnosis.

Colmenter, L.; Sajo-Bohus, L.; Liendo, J. A.; Greaves, E. D.; Coelho, D.; Barros, H.; Castillo, J.; Esteves, L. M.; Ruiz, N.; Morales, L.; Lugo, I.

2007-10-01

46

A multi-millennial reconstruction of the total solar irradiance from the carbon radioisotope production rate  

NASA Astrophysics Data System (ADS)

The total solar irradiance (TSI) changes by about 0.1% between solar activity minimum and maximum. In addition to this cyclic variation, a secular variation in the irradiance is also plausible. Recent models suggest that the magnitude of the secular increase in the TSI since the Maunder Minimum was comparable to the solar cycle variation. Detailed reconstructions of irradiance since the Maunder minimum are common, but on longer timescales hardly any quantitative reconstructions are available, due to the lack of solar data. Here we present a reconstruction of solar irradiance on millennial time scales. The reconstruction involves two steps: (1) modelling of the evolution of the solar open magnetic flux from the production rate of 14C (as earlier carried out by Solanki et al. 2004 and Usoskin et al. 2007) and (2) evaluation of the solar irradiance from the calculated open magnetic flux. The model is tested by comparing to the TSI reconstruction from the sunspot number for the last 4 centuries. We also discuss limits and uncertainties of the model.

Vieira, L. A.; Krivova, N.; Solanki, S.; Balmaceda, L.

2008-05-01

47

ANNUAL TECHNICAL PROGRESS REPORT OF RADIOISOTOPE POWER SYSTEMS MATERIALS PRODUCTION AND TECHNOLOGY PROGRAM TASKS FOR OCTOBER 1, 2010 THROUGH SEPTEMBER 30, 2011  

SciTech Connect

The Office of Space and Defense Power Systems of the Department of Energy (DOE) provides Radioisotope Power Systems (RPS) for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators were supplied by the DOE to the National Aeronautics and Space Administration (NASA) for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. For the Cassini Mission, the Oak Ridge National Laboratory (ORNL) produced carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) used in the generators. These components were also produced for the Pluto New Horizons and Mars Science Lab missions launched in January 2006 and November 2011respectively. The ORNL has been involved in developing materials and technology and producing components for the DOE for nearly four decades. This report reflects program guidance from the Office of RPS for fiscal year (FY) 2011. Production activities for prime quality (prime) CBCF insulator sets, iridium alloy blanks and foil, and CVS are summarized in this report. Technology activities are also reported that were conducted to improve the manufacturing processes, characterize materials, or to develop information for new RPS. Work has also been initiated to establish fabrication capabilities for the Light Weight Radioisotope Heater Units.

King, James F [ORNL

2012-05-01

48

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1983  

SciTech Connect

This document lists DOE's radioisotope production and distribution activities by its facilities at Argonne National Laboratory; Pacific Northwest Laboratory; Idaho Operations Office; Los Alamos National Laboratory; Oak Ridge National Laboratory; Savannah River Plant; and UNC Nuclear Industries, Inc. The information is divided into five sections: isotope suppliers, facility contacts, and isotopes or services supplied; lists of customers, suppliers and isotopes purchased; list of isotopes purchased cross-referenced to customer codes; geographic locations of radioisotope customers; and radioisotope sales and transfers - FY 1983.

Baker, D.A.

1984-08-01

49

Determination of boron and lithium by recording the products from (n, alpha) reactions  

NASA Technical Reports Server (NTRS)

Irradiation with thermal neutrons in the VVR-S reactor provides a nondestructive method for determining the presence of boron and lithium in solids. The charged particles produced in the reactions Li-6(n,alpha)H-3 and B-10(n,alpha)Li-7 were detected using CsI single crystal. For alpha-particle spectrometry in the boron determination, an ionization chamber (W and Sn electrodes, 99% Ar + 1% H2) was developed allowing both absolute and relative measurements. In determining boron in lithium-containing samples, both scintillation and ionization chambers are used. In determining lithium in minerals, the error was 1.5%, and the sensitivity 0.00005 wt.%. In the determination of boron in SiC with a concentration of boron approximately (3 plus or minus 2) the error given by the alpha-range uncertainty was 15%.

Lobanov, Y. M.; Zverev, B. P.; Simakhin, Y. F.; Usmanova, M. M.

1978-01-01

50

Green Approach--Multicomponent Production of Boron--Containing Hantzsch and Biginelli Esters  

PubMed Central

Multicomponent reactions are excellent methods that meet the requirements of green chemistry, by reducing the number of steps, and consequently reducing purification requirements. Accordingly, in this work, 11 novel hybrid-boron-containing molecules, namely eight 1,4-dihydropyridines and three 3,4-dihydropyrimidinones, derived from formylphenylboronic acids (ortho, meta and para), were obtained using a green approach, involving H-4CR and B-3CR practices, in the presence of ethanol, which is a green solvent, and using three comparatively different modes of activation (mantle heating, yield 3%–7% in 24 h, Infrared Radiation (IR) irradiation, yield 12%–17% in 12 h, and microwave irradiation, yield 18%–80%, requiring very low reaction times of 0.25–0.33 h). In addition, as a green-approach is offered, a convenient analysis, of the 12 green chemistry principles for the overall procedure was performed. Finally, since all the products are new, characterizations were carried out using common analytic procedures (1H, 11B, and 13C NMR, FAB+MS, HRMS, and IR). The accurate mass data of unexpected ions related to interactions between thioglycerol and the expected products, in the FAB+-mode, enabled unequivocal characterization of the target molecules. PMID:23364612

Martinez, Joel; Romero-Vega, Stephany; Abeja-Cruz, Rita; Alvarez-Toledano, Cecilio; Miranda, Rene

2013-01-01

51

Process for making boron nitride using sodium cyanide and boron  

DOEpatents

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.

Bamberger, Carlos E. (Oak Ridge, TN)

1990-01-01

52

Minerals Yearbook 1989: Boron  

Microsoft Academic Search

U.S. production and sales of boron minerals and chemicals decreased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to distributors, textile-grade glass fibers, and borosilicate glasses. California was the only domestic source of boron minerals. The United States continued to provide essentially all of its own supply while maintaining a strong position

Lyday

1990-01-01

53

Boron nanotubes.  

PubMed

A survey of novel classes of nanotubular materials based on boron is presented. Pure boron nanotubes are a consequence of a general Aufbau principle for boron clusters and solid boron phases, which postulates various novel boron materials besides the well-known bulk phases of boron based on boron icosahedra. Furthermore, several numerical studies suggest the existence of a large family of compound nanotubular materials derived from crystalline AlB2. We compare these novel boron-based nanotubular materials to standard nanotubular systems built from carbon, and point out a number of remarkable structural and electronic properties that make boron-based nanotubular materials an ideal component for composite nanodevices and extended nanotubular networks. PMID:16208735

Quandt, Alexander; Boustani, Ihsan

2005-10-14

54

Magnetron sputtered boron films  

DOEpatents

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.

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

1998-06-16

55

Magnetron sputtered boron films  

DOEpatents

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.

Makowiecki, Daniel M. (Livermore, CA); Jankowski, Alan F. (Livermore, CA)

1998-01-01

56

Effect of boron application on seed production of New Zealand herbage legumes  

Microsoft Academic Search

Six rates of boron (B) were applied to 2 white clovers (Trifolium repens L.), alsike clover (Trifolium hybridum L.), 3 red clovers (Trifolium pratense L.), and lucerne (Medicago sativa L.) in the glasshouse on a soil which was known to be low in available B. None of the 7 cultivars produced seed without added B, and red clovers also did

C. G. Sherrell

1983-01-01

57

Determination and production of an optimal neutron energy spectrum for boron neutron capture therapy  

Microsoft Academic Search

An accelerator-based neutron irradiation facility employing an electrostatic quadrupole (ESQ) accelerator for Boron Neutron Capture Therapy (BNCT) has been proposed at Lawrence Berkeley National Laboratory. In this dissertation, the properties of an ideal neutron beam for delivering a maximized dose to a glioblastoma multiforme tumor in a reasonable time while minimizing the dose to healthy tissue is examined. A variety

Darren Leo Bleuel

2003-01-01

58

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1982  

SciTech Connect

The radioisotope production and distribution activities by facilities at Argonne National Laboratory, Pacific Northwest Laboratory, Brookhaven National Laboratory, Hanford Engineering Development Laboratory, Idaho Operations Office, Los Alamos Scientific Laboratory, Oak Ridge National Laboratory, Savannah River Laboratory, and UNC Nuclear Industries, Inc. are listed. The information is divided into five sections: isotope suppliers, facility, contacts, and isotopes or services supplied; alphabetical list of customers, and isotopes purchased; alphabetical list of isotopes cross-referenced to customs numbers; geographical location of radioisotope customers; and radioisotope sales and transfers-FY 1982. (MHR)

Richards, M.P.

1983-08-01

59

Determination and production of an optimal neutron energy spectrum for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

An accelerator-based neutron irradiation facility employing an electrostatic quadrupole (ESQ) accelerator for Boron Neutron Capture Therapy (BNCT) has been proposed at Lawrence Berkeley National Laboratory. In this dissertation, the properties of an ideal neutron beam for delivering a maximized dose to a glioblastoma multiforme tumor in a reasonable time while minimizing the dose to healthy tissue is examined. A variety of materials, beam shaping assemblies, and neutron sources were considered to deliver a neutron spectrum as close to the calculated idealized spectrum as possible. Several optimization studies were performed to determine the best proton energy and moderator material to maximize the efficacy of an accelerator-based BNCT facility utilizing the 7Li(p,n)7Be reaction as a neutron source. A new, faster method of performing such an optimization was developed, known as the "Ubertally" method, in which data from a single Monte Carlo simulation is reweighted to produce results for any neutron spatial, energy and angular source distribution. Results were confirmed experimentally at Lawrence Berkeley National Laboratory's 88? cyclotron. Thermal fluxes in this experiment were found to be approximately 30% lower than expected, but the depth-dose profile was confirmed to within 8% maximum deviation. A final beam shaping assembly is then recommended. Utilizing a material known as Fluental as a moderating material, deep-seated tumor doses 50% higher than that delivered by clinical trials at the Brookhaven Medical Research Reactor (BMRR) are predicted. The final recommended design should contain a 37 cm thickness of Fluental(TM) moderator, a 1--2 cm gamma shield, an Al2O3 reflector, a V-shaped aluminum-backed or copper-backed source with heavy water cooling, and a 13 cm lithiated polyethylene delimiter. This design would be operated at 2.4 MeV proton energy at 20 mA to conduct treatments in less than an hour and a half. However, this design may be easily altered depending on the changing needs of the treatment facility. It is therefore concluded that production of an accelerator-based BNCT facility using an ESQ accelerator and a 7Li target is feasible and can produce a superior quality neutron beam.

Bleuel, Darren Leo

60

Markets for reactor-produced non-fission radioisotopes  

SciTech Connect

Current market segments for reactor produced radioisotopes are developed and reported from a review of current literature. Specific radioisotopes studied in is report are the primarily selected from those with major medical or industrial markets, or those expected to have strongly emerging markets. Relative market sizes are indicated. Special emphasis is given to those radioisotopes that are best matched to production in high flux reactors such as the Advanced Test Reactor (ATR) at the Idaho National Engineering Laboratory or the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory. A general bibliography of medical and industrial radioisotope applications, trends, and historical notes is included.

Bennett, R.G.

1995-01-01

61

Hydrogen-catalyzed, pilot-scale production of small-diameter boron nitride nanotubes and their macroscopic assemblies.  

PubMed

Boron nitride nanotubes (BNNTs) exhibit a range of properties that are as compelling as those of carbon nanotubes (CNTs); however, very low production volumes have prevented the science and technology of BNNTs from evolving at even a fraction of the pace of CNTs. Here we report the high-yield production of small-diameter BNNTs from pure hexagonal boron nitride powder in an induction thermal plasma process. Few-walled, highly crystalline small-diameter BNNTs (?5 nm) are produced exclusively and at an unprecedentedly high rate approaching 20 g/h, without the need for metal catalysts. An exceptionally high cooling rate (?10(5) K/s) in the induction plasma provides a strong driving force for the abundant nucleation of small-sized B droplets, which are known as effective precursors for small-diameter BNNTs. It is also found that the addition of hydrogen to the reactant gases is crucial for achieving such high-quality, high-yield growth of BNNTs. In the plasma process, hydrogen inhibits the formation of N2 from N radicals and promotes the creation of B-N-H intermediate species, which provide faster chemical pathways to the re-formation of a h-BN-like phase in comparison to nitridation from N2. We also demonstrate the fabrication of macroscopic BNNT assemblies such as yarns, sheets, buckypapers, and transparent thin films at large scales. These findings represent a seminal milestone toward the exploitation of BNNTs in real-world applications. PMID:24807071

Kim, Keun Su; Kingston, Christopher T; Hrdina, Amy; Jakubinek, Michael B; Guan, Jingwen; Plunkett, Mark; Simard, Benoit

2014-06-24

62

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1980  

SciTech Connect

The sixteenth edition of the radioisotope customer list was prepared at the request of the Office of Health and Environmental Research, Office of energy Research, Department of Energy (DOE). This document lists DOE's radioisotope production and distribution activities by its facilities at Argonne National Laboratory; Pacific Northwest Laboratory; Brookhaven National Laboraory; Hanford Engineering Development Laboratory; Idaho Operations Office; Los Alamos Scientific Laboratory; Mound Facility; Oak Ridge National Laboratory; Savannah River Laboratory; and UNC Nuclear Industries, Inc. The information is divided into five sections: (1) isotope suppliers, facility, contracts and isotopes or services supplied; (2) alphabetical list of customers, and isotopes purchased; (3) alphabetical list of isotopes cross-referenced to customer numbers; (4) geographical location of radioisotope customers; and (5) radioisotope sales and transfers-FY 1980.

Burlison, J.S. (comp.)

1981-08-01

63

The production of patient dose level 99mTc medical radioisotope using laser-driven proton beams  

NASA Astrophysics Data System (ADS)

The medical isotope 99mTc (technetium) is used in over 30 million nuclear medical procedures annually, accounting for over 80% of the worldwide medical isotope usage. Its supply is critical to the medical community and a worldwide shortage is expected within the next few decades as current fission reactors used for its generation reach their end of life. The cost of build and operation of replacement reactors is high and as such, alternative production mechanisms are of high interest. Laser-accelerated proton beams have been widely discussed as being able to produce Positron Emission Tomography (PET) isotopes once laser architecture evolved to high repetition rates and energies. Recent experimental results performed on the Vulcan Laser Facility in the production of 99mTc through 100Mo (p,2n) 99mTc demonstrate the ability to produce this critical isotope at the scales required for patient doses using diode pumped laser architecture currently under construction. The production technique, laser and target requirements are discussed alongside a timeline and cost for a prototype production facility.

Clarke, R.; Dorkings, S.; Neely, D.; Musgrave, I.

2013-05-01

64

Miniature Radioisotope Power Source  

NASA Technical Reports Server (NTRS)

Proposed miniature power source generates electricity for years from heat developed in small radioisotope unit without addition of fuel or dependence on sunlight. Called powerstick, is relatively inexpensive, lightweight, and rugged. Supplies power to small vehicles or scientific instruments in remote locations on Earth or in outer space. Envisioned uses include Mars miniature rovers and monitoring equipment for toxic or nuclear storage sites.

Chmielewski, Artur B.

1995-01-01

65

Radioisotope powered light sources  

Microsoft Academic Search

The background and current status of the use of radioisotopes to excite phosphors to produce visible light are discussed. Current energy conservation needs provided the incentive for the development of illuminators for air field markers using both byproduct krypton-85 and processed tritium.

F. N. Case; W. C. Remini

1980-01-01

66

Radioisotope powered light sources  

NASA Astrophysics Data System (ADS)

The background and current status of the use of radioisotopes to excite phosphors to produce visible light are discussed. Current energy conservation needs provided the incentive for the development of illuminators for air field markers using both byproduct krypton-85 and processed tritium.

Case, F. N.; Remini, W. C.

1980-10-01

67

Nuclear model calculations on the production of 125,123Xe and 133,131,129,128Ba radioisotopes  

NASA Astrophysics Data System (ADS)

In this study, production rates of 125,123Xe and 133,131,129,128Ba medical isotopes produced by 127I( p, 3 n)125Xe, 127I( p, 5 n)123Xe, 133Cs( p, n)133 mg Ba, 133Cs( p, 3 n)131 mg Ba, 133Cs( p, 5 n)129Ba, and 133Cs( p, 6 n)128Ba reactions have been investigated up to 100 MeV incident proton energy. The preequilibrium calculations involve the hybrid model, the geometry-dependent hybrid model and the cascade exciton model. The calculated results are compared with the experimental data taken from the literature.

Aydin, A.; Pekdo?an, H.; Tel, E.; Kaplan, A.

2012-03-01

68

Reducing Boron Toxicity by Microbial Sequestration  

SciTech Connect

While electricity is a clean source of energy, methods of electricity-production, such as the use of coal-fired power plants, often result in significant environmental damage. Coal-fired electrical power plants produce air pollution, while contaminating ground water and soils by build-up of boron, which enters surrounding areas through leachate. Increasingly high levels of boron in soils eventually overcome boron tolerance levels in plants and trees, resulting in toxicity. Formation of insoluble boron precipitates, mediated by mineral-precipitating bacteria, may sequester boron into more stable forms that are less available and toxic to vegetation. Results have provided evidence of microbially-facilitated sequestration of boron into insoluble mineral precipitates. Analyses of water samples taken from ponds with high boron concentrations showed that algae present contained 3-5 times more boron than contained in the water in the samples. Boron sequestration may also be facilitated by the incorporation of boron within algal cells. Experiments examining boron sequestration by algae are in progress. In bacterial experiments with added ferric citrate, the reduction of iron by the bacteria resulted in an ironcarbonate precipitate containing boron. An apparent color change showing the reduction of amorphous iron, as well as the precipitation of boron with iron, was more favorable at higher pH. Analysis of precipitates by X-ray diffraction, scanning electron microscopy, and inductively coupled plasma mass spectroscopy revealed mineralogical composition and biologicallymediated accumulation of boron precipitates in test-tube experiments.

Hazen, T.; Phelps, T.J.

2002-01-01

69

Experimental study of the 165Ho(p,n) nuclear reaction for production of the therapeutic radioisotope 165Er  

NASA Astrophysics Data System (ADS)

The 10.3 h half life radionuclide 165Er, decaying by electron capture to stable 165Ho, is an excellent candidate for Auger-electron therapy. In the frame of a systematic study of charged particle production routes of 165Er, the excitation function of the 165Ho(p,n) 165Er reaction was measured up to 35 MeV by using a stacked foil irradiation technique and X-ray spectroscopy. The measured excitation function shows a significant energy shift when compared to the only experimental dataset measured earlier and an acceptable agreement with the results of different nuclear reaction model codes. The thick target yields calculated from the excitation function at typical energies available at small cyclotrons ( Ep = 11 MeV and Ep = 15 MeV) are 41 MBq/?Ah = 11 GBq/C and 75 MBq/?Ah = 21 GBq/C, respectively.

Tárkányi, F.; Hermanne, A.; Takács, S.; Ditrói, F.; Király, B.; Kovalev, S. F.; Ignatyuk, A. V.

2008-08-01

70

Minerals Yearbook 1989: Boron  

SciTech Connect

U.S. production and sales of boron minerals and chemicals decreased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to distributors, textile-grade glass fibers, and borosilicate glasses. California was the only domestic source of boron minerals. The United States continued to provide essentially all of its own supply while maintaining a strong position as a source of sodium borate products and boric acid exported to foreign markets. Supplementary U.S. imports of Turkish calcium borate and calcium-sodium borate ores, borax, and boric acid, primarily for various glass uses, continued.

Lyday, P.A.

1990-08-01

71

Taming Highly Charged Radioisotopes  

NASA Astrophysics Data System (ADS)

The precise and accurate mass of short-lived radioisotopes is a very important parameter in physics. Contribution to the improvement of nuclear models, metrological standard fixing and tests of the unitarity of the Caibbibo-Kobayashi-Maskawa (CKM) matrix are a few examples where the mass value plays a major role. TRIUMF's ion trap for atomic and nuclear physics (TITAN) is a unique facility of three online ion traps that enables the mass measurement of short-lived isotopes with high precision (˜10-8). At present TITAN's electron beam ion trap (EBIT) increases the charge state to increase the precision, but there is no facility to significantly reduce the energy spread introduced by the charge breeding process. The precision of the measured mass of radioisotopes is linearly dependent on the charge state while the energy spread of the charged radioisotopes affects the precision adversely. To boost the precision level of mass measurement at TITAN without loosing too many ions, a cooler Penning trap (CPET) is being developed. CPET is designed to use either positively (proton) or negatively (electron) charged particles to reduce the energy spread via sympathetic cooling. Off-line setup of CPET is complete. Details of the working principles and updates are presented

Chowdhury, Usman; Eberhardt, Benjamin; Jang, Fuluni; Schultz, Brad; Simon, Vanessa; Delheij, Paul; Dilling, Jens; Gwinner, Gerald

2012-10-01

72

Boron Clusters  

NSDL National Science Digital Library

The May featured molecules are discussed in the Viewpoints article "Boron Clusters Come of Age". The review paper by Russell N. Grimes on boron clusters reminds us both of the past impact that these interesting structures have had on the development of our understanding of cluster chemistry and on the future development of what one might refer to as "post-fullerene" clusters. The wide range of structures found in this paper admirably illustrate the structural flexibility arising from clusters of a variety of symmetries and degrees of boron replacement with carbon and other atoms.

73

Radioisotopes as Political Instruments, 1946-1953.  

PubMed

The development of nuclear "piles," soon called reactors, in the Manhattan Project provided a new technology for manufacturing radioactive isotopes. Radioisotopes, unstable variants of chemical elements that give off detectable radiation upon decay, were available in small amounts for use in research and therapy before World War II. In 1946, the U.S. government began utilizing one of its first reactors, dubbed X-10 at Oak Ridge, as a production facility for radioisotopes available for purchase to civilian institutions. This program of the U.S. Atomic Energy Commission was meant to exemplify the peacetime dividends of atomic energy. The numerous requests from scientists outside the United States, however, sparked a political debate about whether the Commission should or even could export radioisotopes. This controversy manifested the tension in U.S. politics between scientific internationalism as a tool of diplomacy, associated with the aims of the Marshall Plan, and the desire to safeguard the country's atomic monopoly at all costs, linked to American anti-Communism. This essay examines the various ways in which radioisotopes were used as political instruments-both by the U.S. federal government in world affairs, and by critics of the civilian control of atomic energy-in the early Cold War. PMID:20725612

Creager, Angela N H

2009-01-01

74

Increased Abundance of Proteins Involved in Phytosiderophore Production in Boron-Tolerant Barley1[C][W  

PubMed Central

Boron (B) phytotoxicity affects cereal-growing regions worldwide. Although B-tolerant barley (Hordeum vulgare) germplasm is available, molecules responsible for this tolerance mechanism have not been defined. We describe and use a new comparative proteomic technique, iTRAQ peptide tagging (iTRAQ), to compare the abundances of proteins from B-tolerant and -intolerant barley plants from a ‘Clipper’ × ‘Sahara’ doubled-haploid population selected on the basis of a presence or absence of two B-tolerance quantitative trait loci. iTRAQ was used to identify three enzymes involved in siderophore production (Iron Deficiency Sensitive2 [IDS2], IDS3, and a methylthio-ribose kinase) as being elevated in abundance in the B-tolerant plants. Following from this result, we report a potential link between iron, B, and the siderophore hydroxymugineic acid. We believe that this study highlights the potency of the iTRAQ approach to better understand mechanisms of abiotic stress tolerance in cereals, particularly when applied in conjunction with bulked segregant analysis. PMID:17478636

Patterson, John; Ford, Kris; Cassin, Andrew; Natera, Siria; Bacic, Antony

2007-01-01

75

Therapeutic clinical applications of reactor-produced radioisotopes  

SciTech Connect

One of the most rapidly growing areas of clinical nuclear medicine is the therapeutic use of radioisotopes for applications in oncology, rheumatology and, more recently, interventional cardiology. With the rapidly increasing development and evaluation of new agents, their introduction into clinical use, and commercialization, the availability of high levels of therapeutic reactor-produced neutron-rich radioisotopes is of increasing importance. The goals of this paper are to discuss the issues associated with optimization of the production and processing of reactor-produced radioisotopes for therapy, with special emphasis on {sup 188}W, and the optimization of the use of the {sup 188}W/{sup 188}Re generator. In addition, other key examples of therapeutic radioisotopes of current interest and their specific clinical applications are discussed.

Knapp, F.F. Jr. [Oak Ridge National Lab., TN (United States)

1997-12-01

76

Silicon Carbide Radioisotope Batteries  

NASA Technical Reports Server (NTRS)

The substantial radiation resistance and large bandgap of SiC semiconductor materials makes them an attractive candidate for application in a high efficiency, long life radioisotope battery. To evaluate their potential in this application, simulated batteries were constructed using SiC diodes and the alpha particle emitter Americium Am-241 or the beta particle emitter Promethium Pm-147. The Am-241 based battery showed high initial power output and an initial conversion efficiency of approximately 16%, but the power output decayed 52% in 500 hours due to radiation damage. In contrast the Pm-147 based battery showed a similar power output level and an initial conversion efficiency of approximately 0.6%, but no degradation was observed in 500 hours. However, the Pm-147 battery required approximately 1000 times the particle fluence as the Am-242 battery to achieve a similar power output. The advantages and disadvantages of each type of battery and suggestions for future improvements will be discussed.

Rybicki, George C.

2005-01-01

77

NASA: Radioisotope Power Systems  

NSDL National Science Digital Library

This is a multimedia overview of RPS (radioisotope power systems), a type of nuclear energy technology that uses heat to produce electricity for powering spacecraft. The heat is produced by the natural radioactive decay of plutonium-238. RPS systems have been in use for more than 50 years, and could continue to support missions to some of the most extreme environments in the solar system. Advantages of RPS include: continuous operation over long-duration space missions, largely independent of changes in sunlight, temperature, charged particle radiation, or surface conditions like thick clouds or dust. This resource is part of NASA's Solar System Exploration website. It includes videos, 3D interactive animations, illustrations, schematics of RPS components, and fact sheets about how the technology has been used in past missions.

2012-10-30

78

Boron-carbon-silicon polymers and ceramic and a process for the production thereof  

NASA Technical Reports Server (NTRS)

The present invention relates to a process for the production of an organoborosilicon preceramic polymer. The polymer is prepared by the reaction of vinylsilane or vinlymethylsilanes (acetylene)silane or acetylene alkyl silanes and borane or borane derivatives. The prepolymer form is pyrolyzed to produce a ceramic article useful in high temperature (e.g., aerospace) or extreme environmental applications.

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

1992-01-01

79

Cosmic Ray Models for Early Galactic Lithium, Beryllium, and Boron Production  

E-print Network

To understand better the early galactic production of Li, Be, and B by cosmic ray spallation and fusion reactions, the dependence of these production rates on cosmic ray models and model parameters is examined. The sensitivity of elemental and isotopic production to the cosmic ray pathlength magnitude and energy dependence, source spectrum, spallation kinematics, and cross section uncertainties is studied. Changes in these model features, particularly those features related to confinement, are shown to alter the Be- and B-versus-Fe slopes {}from a na\\"{\\i}ve quadratic relation. The implications of our results for the diffuse $\\gamma$-ray background are examined, and the role of chemical evolution and its relation to our results is noted. It is also noted that the unmeasured high energy behavior of $\\alpha+\\alpha$ fusion can lead to effects as large as a factor of 2 in the resultant yields. Future data should enable Population II Li, Be, and B abundances to constrain cosmic ray models for the early Galaxy.

Brian Fields; Keith Olive; David Schramm

1994-05-11

80

Producing carbon stripper foils containing boron  

SciTech Connect

Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

Stoner, J. O. Jr. [ACF-Metals (Arizona Carbon Foil Co., Inc.), 2239 E. Kleindale Road, Tucson, AZ 85719 (United States)

2012-12-19

81

Producing carbon stripper foils containing boron  

NASA Astrophysics Data System (ADS)

Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

Stoner, J. O., Jr.

2012-12-01

82

Mineral resource of the month: boron  

USGS Publications Warehouse

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.

Crangle, Robert D., Jr.

2012-01-01

83

Characterization of electrodeposited elemental boron  

SciTech Connect

Elemental boron was produced through electrowinning from potassium fluoroborate dissolved in a mixture of molten potassium fluoride and potassium chloride. The characteristics of the electrodeposited boron (raw boron) as well as the water and acid-leached product (processed boron) were studied. The chemical purity, specific surface area, size distribution of particles and X-ray crystallite size of the boron powders were investigated. The morphology of the deposits was examined using scanning electron microscopy (SEM). The chemical state of the matrix, as well as the impurity phases present in them, was established using X-ray photoelectron spectroscopy (XPS). In order to interpret and understand the results obtained, a thermodynamic analysis was carried out. The gas-phase corrosion in the head space as well as the chemistry behind the leaching process were interpreted using this analysis. The ease of oxidation of these powders in air was investigated using differential thermal analysis (DTA) coupled with thermogravimetry (TG). From the results obtained in this study it was established that elemental boron powder with a purity of 95-99% could be produced using a high temperature molten salt electrowinning process. The major impurities were found to be oxygen, carbon, iron and nickel.

Jain, Ashish [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Anthonysamy, S. [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India)], E-mail: sas@igcar.gov.in; Ananthasivan, K.; Ranganathan, R. [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India); Mittal, Vinit; Narasimhan, S.V. [Water and Steam Chemistry Division, BARC (F), Kalpakkam, 603102 (India); Vasudeva Rao, P.R. [Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102 (India)

2008-07-15

84

BORON--2000 14.1 By Phyllis A. Lyday  

E-print Network

sold to distributors, 9%; borosilicate glasses, 7%; soaps and detergents, 7%; enamels, frits the world's largest producers of boron (table 7). The glass industry, which remained the largest domestic market for boron production in 2000, accounted for 76% of boron consumption. Insulation-grade glass

85

Boron Nitride Nanotubes  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

86

Radioisotopes for research on and control of mosquitos  

PubMed Central

Practical applications of radioactive isotopes in medicine, science, and industry have multiplied enormously during the past five years. In this paper, the author attempts to gather what is known about the use of radioactive isotopes in the research on malaria control. The development of the uranium pile for large-scale production of radioisotopes and technical progress in the making of reliable electronic equipment have greatly contributed to the application of radioactive tracers in biological research. The present knowledge of radioisotopes in mosquito and in insecticide research is discussed. ImagesFIG. 1 PMID:13404435

Bruce-Chwatt, Leonard J.

1956-01-01

87

Magnetron sputtered boron films and Ti/B multilayer structures  

DOEpatents

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. 6 figs.

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

1995-02-14

88

Magnetron sputtered boron films and TI/B multilayer structures  

DOEpatents

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.

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

1993-04-20

89

Magnetron sputtered boron films and TI/B multilayer structures  

DOEpatents

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.

Makowiecki, Daniel M. (Livermore, CA); Jankowski, Alan F. (Livermore, CA)

1993-01-01

90

Magnetron sputtered boron films and Ti/B multilayer structures  

DOEpatents

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.

Makowiecki, Daniel M. (Livermore, CA); Jankowski, Alan F. (Livermore, CA)

1995-01-01

91

New measurement and evaluation of the excitation function of the 186W(p,n) nuclear reaction for production of the therapeutic radioisotope 186Re  

NASA Astrophysics Data System (ADS)

The excitation function up to 30 MeV was remeasured by the activation method for the production of 186Re via the 186W(p,n) reaction. The available experimental data were analyzed, corrected and compared with the calculated results of the ALICE-IPPE, GNASH and EMPIRE theoretical model codes. The experimental data set has still to be improved before reliable recommended values for optimization of batch production can be proposed.

Tárkányi, F.; Hermanne, A.; Takács, S.; Ditrói, F.; Kovalev, F.; Ignatyuk, A. V.

2007-11-01

92

Boron Fixation by Illites  

Microsoft Academic Search

The mechanism of boron uptake by clays, especially illitic clays, and the factors which control such uptake have long been debated issues. In an attempt to answer some of the questions of the controversy, three illites were treated in solutions containing boron. In the study, boron concen- tration, salinity, temperature, and time were varied independently over rather wide ranges. For

Elton L. Couch; RALPH E. GRIM

1968-01-01

93

Boron and boron carbide coatings by vapor deposition  

Microsoft Academic Search

The Bureau of Mines investigated the formation of boron and boron-carbide coatings by vaporphase reactions. Optimum parameters\\u000a were determined for hydrogen reduction of boron trichloride and for the formation of boron-carbide coatings on graphite by\\u000a reaction with the deposited boron. At 1300°C, about 85 pct of the boron was deposited. Tungsten substrates did not react with\\u000a the boron deposit; other

Andrew A. Cochran; James B. Stephenson

1970-01-01

94

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1985  

SciTech Connect

This document describes radioisotope distribution from DOE facilities to private firms including foreign and other DOE facilities. The information is divided into five sections: (1) isotope suppliers, facility contacts, and isotopes or services supplied; (2) customers, suppliers, and isotopes purchased; (3) isotopes purchased cross-referenced with customer numbers; (4) geographic locations of radioisotope customers; and (5) radioisotope sales and transfer - FY 1985.

Baker, D.A.

1986-08-01

95

Lithium-Beryllium-Boron : Origin and Evolution  

E-print Network

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

Elisabeth Vangioni-Flam; Michel Casse; Jean Audouze

1999-07-13

96

Respiratory and eye irritation from boron oxide and boric acid dusts  

Microsoft Academic Search

Boron oxide has been shown in animals to irritate the respiratory mucosa and conjuctiva. The present study was undertaken to determine whether exposures to boron oxide and its hydration product, boric acid, cau

David H. Garabrant; Leslie Bernstein; John M. Peters; Thomas J. Smith

1984-01-01

97

Properties of boron/boron-nitride multilayers  

SciTech Connect

Boron-Nitride films are of interest for their high hardness and wear resistance. Large intrinsic stresses and poor adhesion which often accompany high hardness materials can be moderated through the use of a layered structure. Alternate layers of boron (B) and boron-nitride (BN) are formed by modulating the composition of the sputter gas during deposition from a pure B target. The thin films are characterized with TEM to evaluate the microstructure and with nanoindentation to determine hardness. Layer pair spacing and continuity effects on hardness are evaluated for the B/BN films.

Jankowski, A.F.; Wall, M.A.; Hayes, J.P. [Lawrence Livermore National Lab., CA (United States); Alexander, K.B. [Oak Ridge National Lab., TN (United States)

1996-06-01

98

Radioisotopes and the Age of the Earth  

Microsoft Academic Search

RATE is an acronym applied to a research project investigating radioisotope dating sponsored by the Institute for Creation Research and the Creation Research Society. It stands for Radioisotopes and the Age of The Earth. This article summarizes the purpose, history, and intermediate findings of the RATE project five years into an eight-year effort. It reports on the latest status of

Larry Vardiman; Steven A. Austin; John R. Baumgardner; Eugene F. Chaffin; Donald B. DeYoung; D. Russell Humphreys; Andrew A. Snelling

2003-01-01

99

Radioisotope Thermionic Converters for Space Applications  

Microsoft Academic Search

The recent history of radioisotope thermionics is reviewed, with emphasis on the US. programs, and the prospects for the future are assessed. In radioisotope thermionic converters the emitter heat is generated by the decay of a radioactive isotope. The thermionic converter emitter is mounted directly on a capsule containing the isotope. The rest of the capsule is generally insulated to

Gabor Miskolczy; David P. Lieb

1990-01-01

100

Power from Radioisotopes, Understanding the Atom Series.  

ERIC Educational Resources Information Center

This 1971 revision deals with radioisotopes and their use in power generators. Early developments and applications for the Systems for Nuclear Auxiliary Power (SNAP) and Radioisotope Thermoelectric Generators (RTGs) are reviewed. Present uses in space and on earth are included. Uses in space are as power sources in various satellites and space…

Corliss, William R.; Mead, Robert L.

101

Making Microscopic Cubes Of Boron  

NASA Technical Reports Server (NTRS)

Production of finely divided cubes of boron involves vacuum-deposition technology and requires making of template. Template supports pattern of checkered squares 25 micrometers on side, which are etched 25 micrometers into template material. Template coasted uniformly with paralyene or some similar vacuum coating with low coefficient of adhesion. Intended application to solid rocket fuels, explosives, and pyrotechnics; process used for other applications, from manufacture of pharmaceuticals to processing of nuclear materials.

Faulkner, Joseph M.

1993-01-01

102

Hydrodynamics-assisted scalable production of boron nitride nanosheets and their application in improving oxygen-atom erosion resistance of polymeric composites.  

PubMed

Searching for a method for low-cost, easily manageable, and scalable production of boron nitride nanosheets (BNNSs) and exploring their novel applications are highly important. For the first time we demonstrate that a novel and effective hydrodynamics method, which involves multiple exfoliation mechanisms and thus leads to much higher yield and efficiency, can realize large-scale production of BNNSs. The exfoliation mechanisms that multiple fluid dynamics events contribute towards normal and lateral exfoliation processes could be applied to other layered materials. Up to ~95% of the prepared BNNSs are less than 3.5 nm thick with a monolayer fraction of ~37%. Compared to the conventional sonication and ball milling-based methods, the hydrodynamics method has the advantages of possessing multiple efficient ways for exfoliating BN, being low-cost and environmentally-friendly, producing high quality BNNSs in high yield and efficiency, and achieving concentrated BNNSs dispersions even in mediocre solvents. It is also shown for the first time that BNNSs can be utilized as fillers to improve the oxygen-atom erosion resistance of epoxy composites which are widely used for spacecraft in low earth orbit (LEO) where atom oxygen abounds. An addition of only 0.5 wt% BNNSs can result in a 70% decrease in the mass loss of epoxy composites after atom oxygen exposure equivalent to 160 days in an orbit of ~300 km. Overall, the demonstrated hydrodynamics method shows great potential in large-scale production of BNNSs in industry in terms of yield, efficiency, and environmental friendliness; and the innovative application of BNNSs to enhancing oxygen-atom erosion resistance of polymeric composites in space may provide a novel route for designing light spacecraft in LEO. PMID:24057073

Yi, Min; Shen, Zhigang; Zhang, Wen; Zhu, Jinyang; Liu, Lei; Liang, Shuaishuai; Zhang, Xiaojing; Ma, Shulin

2013-11-01

103

US Department of Energy radioisotope customers with summary of radioisotope shipments, FY 1988  

SciTech Connect

Pacific Northwest Laboratory (PNL) prepared this edition of the radioisotope customer list at the request of the Office of Health and Environmental Research (ER-73), Office of Energy Research, US Department of Energy (DOE). This is the 25th report in a series dating from 1964. This report covers DOE radioisotope sales and distribution activities by its facilities to domestic, foreign and other DOE facilities for FY 1988. The report is divided into five sections: radioisotope suppliers, facility contacts, and radioisotopes or services supplied; a list of customers, suppliers, and radioisotopes purchased; a list of radioisotopes purchased cross-referenced to customer numbers; geographic locations of radioisotope customers; and radioisotope sales and transfers -- FY 1988. Radioisotopes not previously reported in this series of reports were argon-37, arsenic-72, arsenic-73, bismuth-207, gadolinium-151, rhenium-188, rhodium-101, selenium-72, xenon-123 and zirconium-88. The total value of DOE radioisotope sales for FY 1988 was $11.1 million, an increase of 3% from FY 1987.

Van Houten, N.C.

1989-06-01

104

Miniature Radioisotope Thermoelectric Power Cubes  

NASA Technical Reports Server (NTRS)

Cube-shaped thermoelectric devices energized by a particles from radioactive decay of Cm-244 have been proposed as long-lived sources of power. These power cubes are intended especially for incorporation into electronic circuits that must operate in dark, extremely cold locations (e.g., polar locations or deep underwater on Earth, or in deep interplanetary space). Unlike conventional radioisotope thermoelectric generators used heretofore as central power sources in some spacecraft, the proposed power cubes would be small enough (volumes would range between 0.1 and 0.2 cm3) to play the roles of batteries that are parts of, and dedicated to, individual electronic-circuit packages. Unlike electrochemical batteries, these power cubes would perform well at low temperatures. They would also last much longer: given that the half-life of Cm-244 is 18 years, a power cube could remain adequate as a power source for years, depending on the power demand in its particular application.

Patel, Jagdish U.; Fleurial, Jean-Pierre; Snyder, G. Jeffrey; Caillat, Thierry

2004-01-01

105

Plants tolerant of high boron levels.  

PubMed

Reduced crop productivity due to soils containing toxic levels of boron (B) is a worldwide problem in food production. It is estimated that up to 17% of the barley yield losses in southern Australia are caused by B toxicity. We found that the expression of AtBOR4, an Arabidopsis paralog of BOR1, the first identified boron transporter gene, generates plants that are tolerant of high B levels. BOR4 is a polarly localized borate exporter that enhances B efflux from roots. The present study is a foundation for the improvement of crop productivity in soils containing excess B, which are distributed in arid areas of the world. PMID:18048682

Miwa, Kyoko; Takano, Junpei; Omori, Hiroyuki; Seki, Motoaki; Shinozaki, Kazuo; Fujiwara, Toru

2007-11-30

106

The prospects for composites based on boron fibers  

NASA Technical Reports Server (NTRS)

The fabrication of boron filaments and the production of composite materials consisting of boron filaments and organic or metallic matrices are discussed. Problem involving the use of tungsten substrates in the filament fabrication process, the protection of boron fibers with diffusion barrier cladings, and the application of alloy additives in the matrix to lessen the effects of diffusion are considered. Data on the kinetics of the boron fiber/matrix interaction at high temperatures, and the influence of the fiber/matrix interaction on the mechanical properties of the composite are presented.

Naslain, R.

1978-01-01

107

High-calcium coal combustion by-products: Engineering properties, ettringite formation, and potential application in solidification and stabilization of selenium and boron  

SciTech Connect

Four high-calcium coal combustion by-products (two pulverized coal fly ashes (PCFA), a flue gas desulfurization (FGD) residue, and an atmospheric fluidized bed combustion (AFBC) fly ash), were tested for engineering properties and ability to immobilize boron and selenium. These data are needed to explore high-volume utilization in engineered structure or in solidification/stabilization (S/S) technology. Strengths of cured pastes (91 days), varied from as much as 27 MPa (3,900 psi) for one of the PCFA specimens to 4.6 MPa (670 psi) for the FGD specimen. All of the coal by-product pastes developed more than the 0.34 MPa (50 psi) required for S/S applications. Ettringite formation is important to engineering properties and S/S mechanisms. XRD on plain specimens cured for 91 days indicated that the two PCFA pastes formed 5--6% ettringite, the FGD paste formed 22%, and the AFBC paste formed 32%. The hydrating PCFA pastes showed little expansion, the FGD paste contracted slightly, and the AFBC paste expanded by 2.9% over 91 days. Se and B were spiked into the mixing water as sodium selenite, selenate and borate, and for most pastes this had little effect on strength, workability, and expansion. Leaching of ground specimens (cured for 91 days) showed a generally positive correlation between the amount of ettringite formed and resistance to Se and B leaching. Se spiked as selenate was more readily leached than Se spiked as selenite. B showed a high level of fixation.

Solem-Tishmack, J.K.; McCarthy, G.J. [North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry] [North Dakota State Univ., Fargo, ND (United States). Dept. of Chemistry; Docktor, B.; Eylands, K.E.; Thompson, J.S.; Hassett, D.J. [Univ. of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center] [Univ. of North Dakota, Grand Forks, ND (United States). Energy and Environmental Research Center

1995-04-01

108

Branched Polymeric Media: Boron-Chelating Resins from Hyperbranched Polyethylenimine  

E-print Network

, Monrovia, California, United States § Graduate School of Energy, Environment, Water and Sustainability desalination, ultrapure water production, and nuclear power generation. Today's commercial boron magnesium oxide from brines, and (iv) nuclear power generation.1-4 Boron is an essential nutrient for plants

Goddard III, William A.

109

Montan wax improves performance of boron-based wood preservatives  

Microsoft Academic Search

Importance of boron compounds in wood preservation is increasing due to their low environmental impact, high efficacy and the fact that many other active ingredients have been removed from the market after the introduction of the Biocidal Products Directive. The most important drawback of boron is prominent leaching in wet environment. In order to improve their fixation, and performance against

Boštjan Lesar; Polona Kralj; Miha Humar

2009-01-01

110

Boron in the Environment  

Microsoft Academic Search

Boron has recently come to the attention of the U.S. Environmental Protection Agency as a possible contaminant worthy of regulation, but questions must still be addressed before a regulatory determination can take place. This article reviews current knowledge about boron as it pertains to water treatment and the environment so that informed decisions can be made regarding regulations and direction

JEFFREY L. PARKS; MARC EDWARDS

2005-01-01

111

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1987  

SciTech Connect

This edition of the radioisotope customer list was prepared at the request of the Office of Health and Environmental Research (ER-73), Office of Energy Research, US Department of Energy (DOE). This document describes radioisotope distribution from DOE facilities to private firms, including foreign and other DOE facilities. The information is divided into five sections: 1) isotope suppliers, facility contact, and isotopes or services supplied; 2) customers, suppliers, and isotopes purchased; 3) isotopes purchased cross- referenced with customer numbers; 4) geographic locations of radioisotope customers; and 5) radioisotope sales and transfers for fiscal year 1987.

Lamar, D.A.; Van Houten, N.C.

1988-08-01

112

List of DOE radioisotope customers with summary of radioisotope shipments, FY 1984  

SciTech Connect

This edition of the radioisotope customer list was prepared at the request of the Office of Health and Environmental Research (ER-73), Office of Energy Research, Department of Energy (DOE). This document describes radioisotope distribution from DOE facilities to private firms including foreign and other DOE facilities. The information is divided into five sections: (1) isotope suppliers, facility contacts, and isotopes or services supplied; (2) customers, suppliers, and isotopes purchased; (3) isotopes purchased cross-referenced with customer numbers; (4) geographic locations of radioisotope customers; and (5) radioisotope sales and transfers - FY 1984.

Baker, D.A.

1985-08-01

113

Radioisotopes: Problems of Responsibility Arising from Medicine.  

National Technical Information Service (NTIS)

Radioisotopes have brought about great progress in the battle against illnesses of mainly tumoral origin, whether in diagnosis (nuclear medicine) or in treatment (medical radiotherapy). They are important enough therefore to warrant investigation. Such a ...

M. Dupon

1978-01-01

114

Advanced Radioisotope Power Systems Segmented Thermoelectric Research  

NASA Technical Reports Server (NTRS)

Flight times are long; - Need power systems with >15 years life. Mass is at an absolute premium; - Need power systems with high specific power and scalability. 3 orders of magnitude reduction in solar irradiance from Earth to Pluto. Nuclear power sources preferable. The Overall objective is to develop low mass, high efficiency, low-cost Advanced Radioisotope Power System with double the Specific Power and Efficiency over state-of-the-art Radioisotope Thermoelectric Generators (RTGs).

Caillat, Thierry

2004-01-01

115

An investigation on gamma attenuation behaviour of titanium diboride reinforced boron carbide-silicon carbide composites  

NASA Astrophysics Data System (ADS)

In this study, titanium diboride (TiB2) reinforced boron carbide-silicon carbide composites were investigated against Cs-137 and Co-60 gamma radioisotope sources. The composite materials include 70% boron carbide (B4C) and 30% silicon carbide (SiC) by volume. Titanium diboride was reinforced to boron carbide-silicon carbide composites as additive 2% and 4% by volume. Average particle sizes were 3.851 µm and 170 nm for titanium diboride which were reinforced to the boron carbide silicon carbide composites. In the experiments the gamma transmission technique was used to investigate the gamma attenuation properties of the composite materials. Linear and mass attenuation coefficients of the samples were determined. Theoretical mass attenuation coefficients were calculated from XCOM computer code. The experimental results and theoretical results were compared and evaluated with each other. It could be said that increasing the titanium diboride ratio causes higher linear attenuation values against Cs-137 and Co-60 gamma radioisotope sources. In addition decreasing the titanium diboride particle size also increases the linear and mass attenuation properties of the titanium diboride reinforced boron carbide-silicon carbide composites.

Buyuk, Bulent; Beril Tugrul, A.

2014-04-01

116

Stirling Convertor Technologies Being Developed for a Stirling Radioisotope Generator  

NASA Technical Reports Server (NTRS)

The Department of Energy, Lockheed Martin, Stirling Technology Company (STC), and the NASA Glenn Research Center are developing a high-efficiency Stirling Radioisotope Generator (SRG) for NASA space science missions. The SRG is being developed for multimission use, including providing electric power for unmanned Mars rovers and deep space missions. On Mars, rovers with SRGs would be used for missions that might not be able to use photovoltaic power systems, such as exploration at high Martian latitudes and missions of long duration. The projected SRG system efficiency of 23 percent will reduce the required amount of radioisotope by a factor of 4 or more in comparison to currently used Radioisotope Thermoelectric Generators. The Department of Energy recently named Lockheed Martin as the system integration contractor. Lockheed Martin has begun to develop the SRG engineering unit under contract to the Department of Energy, and has contract options to develop the qualification unit and the first flight units. The developers expect the SRG to produce about 114 Wdc at the beginning of mission, using two opposed Stirling convertors and two General Purpose Heat Source modules. STC previously developed the Stirling convertor under contract to the Department of Energy and is now providing further development as a subcontractor to Lockheed Martin. Glenn is conducting an in-house technology project to assist in developing the convertor for space qualification and mission implementation. A key milestone was recently reached with the accumulation of 12 000 hr of long-term aging on two types of neodymium-iron boron permanent magnets. These tests are characterizing any possible aging in the strength or demagnetization resistance of the magnets used in the linear alternator. Preparations are underway for a thermal/vacuum system demonstration and unattended operation during endurance testing of the 55-We Technology Demonstration Convertors. In addition, Glenn is developing a charging system for the convertors to ensure clean fills of the helium working fluid and to monitor levels of any possible contaminants at different test intervals. Possible oxidation effects depend on the level of any oxygen contamination-regenerator materials and displacer radiation shields are now being evaluated for possible oxidation effects.

Thieme, Lanny G.

2003-01-01

117

Generation of Radioisotopes with Accelerator Neutrons by Deuterons  

NASA Astrophysics Data System (ADS)

A new system proposed for the generation of radioisotopes with accelerator neutrons by deuterons (GRAND) is described by mainly discussing the production of 99Mo used for nuclear medicine diagnosis. A prototype facility of this system consists of a cyclotron to produce intense accelerator neutrons from the \\text{natC(d,n) reaction with 40 MeV 2 mA deuteron beams, and a sublimation system to separate \\text{99mTc from an irradiated 100MoO3 sample. About 8.1 TBq/week of 99Mo is produced by repeating irradiation on an enriched 100Mo sample (251 g) with accelerator neutrons for two days three times. It meets about 10% of the 99Mo demand in Japan. The characteristic feature of the system lies in its capability to reliably produce a wide variety of high-quality, carrier-free, carrier-added radioisotopes with a minimum level of radioactive waste without using uranium. The system is compact in size, and easy to operate; therefore it could be used worldwide to produce radioisotopes for medical, research, and industrial applications.

Nagai, Yasuki; Hashimoto, Kazuyuki; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Sato, Nozomi; Kawabata, Masako; Harada, Hideo; Kin, Tadahiro; Tsukada, Kazuaki; Sato, Tetsuya K.; Minato, Futoshi; Iwamoto, Osamu; Iwamoto, Nobuyuki; Seki, Yohji; Yokoyama, Kenji; Shiina, Takehiko; Ohta, Akio; Takeuchi, Nobuhiro; Kawauchi, Yukimasa; Sato, Norihito; Yamabayashi, Hisamichi; Adachi, Yoshitsugu; Kikuchi, Yuji; Mitsumoto, Toshinori; Igarashi, Takashi

2013-06-01

118

Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine.  

PubMed

Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 ± 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ?70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-D-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 ± 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ?70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution. PMID:22827255

Mishra, Himanshu; Yu, Changjun; Chen, Dennis P; Goddard, William A; Dalleska, Nathan F; Hoffmann, Michael R; Diallo, Mamadou S

2012-08-21

119

Process for producing wurtzitic or cubic boron nitride  

DOEpatents

Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described.

Holt, J. Birch (San Jose, CA); Kingman, deceased, Donald D. (late of Danville, CA); Bianchini, Gregory M. (Livermore, CA)

1992-01-01

120

Process for producing wurtzitic or cubic boron nitride  

DOEpatents

Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described.

Holt, J.B.; Kingman, D.D.; Bianchini, G.M.

1992-04-28

121

Boron isotopic compositions of some boron minerals  

Microsoft Academic Search

Boron minerals that have different structural formulae but are supposed to have the same geologic origin have been collected and analyzed for the 11 B \\/ 10 B isotopic ratio. It has been reconfirmed that minerals of marine origin have higher 11 B \\/ 10 B ratios than those of nonmarine origin. It has been found that the sequence of

Takao Oi; Masao Nomura; Masaaki Musashi; Tomoko Ossaka; Makoto Okamoto; Hidetake Kakihana

1989-01-01

122

Direct current sputtering of boron from boron/coron mixtures  

DOEpatents

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.

Timberlake, John R. (Allentown, NJ); Manos, Dennis (Williamsburg, VA); Nartowitz, Ed (Edison, NJ)

1994-01-01

123

Direct current sputtering of boron from boron/carbon mixtures  

SciTech Connect

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.

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

1993-12-31

124

Molecular Structure of boron  

NSDL National Science Digital Library

Boron was founded in 1808 by Sir Humphry Davy and Gay-Lussac and Thenard. It occurs as orthoboric acid in volcanic spring waters and as borates in Boron and colematic. Some sources can also be found in the Mohave Desert. It is used when making glass to keep the glass from breaking under temperature stress. Also if combined with sodium hydroxide and hydrogen peroxide it makes bleach.

2002-08-26

125

Chemical disposition of boron in animals and humans.  

PubMed Central

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

Moseman, R F

1994-01-01

126

An introduction to boron: history, sources, uses, and chemistry.  

PubMed Central

Following a brief overview of the terrestrial distribution of boron in rocks, soil, and water, the history of the discovery, early utilization, and geologic origin of borate minerals is summarized. Modern uses of borate-mineral concentrates, borax, boric acid, and other refined products include glass, fiberglass, washing products, alloys and metals, fertilizers, wood treatments, insecticides, and microbiocides. The chemistry of boron is reviewed from the point of view of its possible health effects. It is concluded that boron probably is complexed with hydroxylated species in biologic systems, and that inhibition and stimulation of enzyme and coenzymes are pivotal in its mode of action. Images Figure 1. PMID:7889881

Woods, W G

1994-01-01

127

ADVANCED RADIOISOTOPE HEAT SOURCE AND PROPULSION SYSTEMS FOR PLANETARY EXPLORATION  

SciTech Connect

The exploration of planetary surfaces and atmospheres may be enhanced by increasing the range and mobility of a science platform. Fundamentally, power production and availability of resources are limiting factors that must be considered for all science and exploration missions. A novel power and propulsion system is considered and discussed with reference to a long-range Mars surface exploration mission with in-situ resource utilization. Significance to applications such as sample return missions is also considered. Key material selections for radioisotope encapsulation techniques are presented.

R. C. O'Brien; S. D. Howe; J. E. Werner

2010-09-01

128

RADIOISOTOPE INVENTORY FOR TSPA-SR  

SciTech Connect

The total system performance assessment for site recommendation (TSPA-SR), on Yucca Mountain, as a site (if suitable) for disposal of radioactive waste, consists of several models. The Waste Form Degradation Model (i.e, source term) of the TSPA-SR, in turn, consists of several components. The Inventory Component, discussed here, defines the inventory of 26 radioisotopes for three representative waste categories: (1) commercial spent nuclear fuel (CSNF), (2) US Department of Energy (DOE) spent nuclear fuel (DSNF), and (3) high-level waste (HLW). These three categories are contained and disposed of in two types of waste packages (WPs)--CSNF WPs and co-disposal WPs, with the latter containing both DSNF and HLW. Three topics are summarized in this paper: first, the transport of radioisotopes evaluated in the past; second, the development of the inventory for the two WP types; and third, the selection of the most important radioisotopes to track in TSPA-SR.

C. Leigh; R. Rechard

2001-01-30

129

Root-growth mechanism for single-walled boron nitride nanotubes in laser vaporization technique.  

SciTech Connect

We present a detailed study of the growth mechanism of single-walled boron nitride nanotubes synthesized by laser vaporization, which is the unique route known to the synthesis of this kind of tube in high quantities. We have performed a nanometric chemical and structural characterization by transmission electron microscopy (high-resolution mode (HRTEM) and electron energy loss spectroscopy) of the synthesis products. Different boron-based compounds and other impurities were identified in the raw synthesis products. The results obtained by the TEM analysis and from the synthesis parameters (temperature, boron, and nitrogen sources) combined with phase diagram analysis to provide identification of the fundamental factors determining the nanotube growth mechanism. Our experiments strongly support a root-growth model that involves the presence of a droplet of boron. This phenomenological model considers the solubility, solidification, and segregation phenomena of the elements present in this boron droplet. In this model, we distinguish three different steps as a function of the temperature: (1) formation of the liquid boron droplet from the decomposition of different boron compounds existing in the hexagonal boron nitride target, (2) reaction of these boron droplets with nitrogen gas present in the vaporization chamber and recombination of these elements to form boron nitride, and (3) incorporation of the nitrogen atoms at the root of the boron particle at active reacting sites that achieves the growth of the tube.

Arenal, R.; Stephan, O.; Cochon, J.-L.; Loiseau, A. (Materials Science Division); (ONERA-CNRS); (UMR CNRS); (ONERA)

2007-12-26

130

Boronated liposome development and evaluation  

SciTech Connect

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

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

1995-11-01

131

Contributions and future of radioisotopes in medical, industrial and space applications  

SciTech Connect

There are 333 isotopes that have a half-life between 1 day and 100,000 years that have a wide variety of applications including public health, medicine,industrial technology, food technology and packaging, agriculture, energy supply, and national security. This paper provides an overview of some of the most extensive applications of radioisotopes including some observations of future uses. Examples are discussed that indicate that the use of radioisotopes is almost unlimited and will continue to grow. There is a growing need for future applications development and production. 12 refs., 1 tab. (BM)

Tingey, G.L.; Dix, G.P.; Wahlquist, E.J.

1990-11-01

132

Contributions and future of radioisotopes in medical, industrial, and space applications  

NASA Astrophysics Data System (ADS)

There are 333 isotopes that have a half-life between 1 day and 100,000 years that have a wide variety of applications including public health, medicine, industrial technology, food technology and packaging, agriculture, energy supply, and national security. This paper provides an overview of some of the most extensive applications of radioisotopes including some observations of future uses. Examples are discussed that indicate that the use of radioisotopes is almost unlimited and will continue to grow. There is a growing need for future applications development and production.

Tingey, G. L.; Dix, G. P.; Wahlquist, E. J.

1990-11-01

133

Mineral of the month: boron  

USGS Publications Warehouse

What does boron have to do with baseball, apple pie, motherhood and Chevrolet? Boron minerals and chemicals are used in the tanning of leather baseballs and gloves; in micro-fertilizer to grow apples and in the glass and enamels of bakewares to cook apple pie; in boron detergents for soaking baby clothes and diapers; and in fiberglass parts for the Chevrolet Corvette.

Lyday, Phyllis A.

2005-01-01

134

Modification of hot cells for general purpose heat source assembly at the radioisotope power systems facility  

NASA Astrophysics Data System (ADS)

Eight existing, unused hot cells currently are being modified for use in the Radioisotope Power Systems Facility (RPSF) to assemble 238Pu-fueled heat sources for Radioisotope Thermoelectric Generators (RTGs). Four air atmosphere cells will be used for storage, decanning, and decontamination of the iridium-clad radioisotope fuel. The remaining four argon atmosphere cells will be used to assemble fuel and graphite components for production and packaging of general purpose heat source (GPHS) assembly modules, which provide heat to drive the thermoelectric conversion process in the generators. The hot cells will be equipped to perform remote and glovebox-type operations. They will provide shielding and contamination control measures to reduce worker radiation exposure to levels within current U.S. Department of Energy (DOE) guidelines. Designs emphasize the Westinghouse Hanford Company (Westinghouse Hanford) as low as reasonably achievable (ALARA) radiation protection policy.

Carteret, Betty A.

1992-01-01

135

Modification of hot cells for general purpose heat source assembly at the Radioisotope Power Systems Facility  

NASA Astrophysics Data System (ADS)

Eight existing, unused hot cells currently are being modified for use in the Radioisotope Power Systems Facility (RPSF) to assemble Pu-238 fueled heat sources for radioisotope thermoelectric generators (RTGs). Four air atmosphere cells will be used for storage, decanning, and decontamination of the iridium-clad radioisotope fuel. The remaining four argon atmosphere cells will be used to assemble fuel and graphite components for production and packaging of general purpose heat source (GPHS) assembly modules, which provide heat to drive the thermoelectric conversion process in the generators. The hot cells will be equipped to perform remote and glovebox-type operations. They will provide shielding and contamination control measures to reduce worker radiation exposure to levels within current U.S. Department of Energy (DOE) guidelines. Designs emphasize the Westinghouse Hanford Company (Westinghouse Hanford) as low as reasonably achievable (ALARA) radiation protection policy.

Carteret, B. A.

1991-09-01

136

Industrial application of radioisotopes in Australia  

SciTech Connect

Over the past 10 years, the Australian Atomic Energy Commission has conducted a wide-ranging program of radioisotopes applications to solve industrial problems of local, regional or national importance. Most of the investigations have been concerned with the behavior of large complex systems. Broadly, the work covers such economically important fields as flow studies,environmental studies and coastal engineering studies.

Easey, J.F.

1988-01-01

137

Selective retention of soluble radioisotopes by fabrics  

SciTech Connect

Wide-area buildup of contamination on laundered protective clothing led the investigators to examine differences in the retention of soluable radioisotopes by selected fabrics. In this paper experimental evidence is provided which suggests selectivity in isotopic retention. Supported by variation in retention between different colors of a fabric, it appears that dyes play a role in controlling the ion selection mechanism.

Wilson, G.R.; Fanelli, S.L. (INS Corp. (US))

1989-06-01

138

NASA Radioisotope Power Conversion Technology NRA Overview  

NASA Technical Reports Server (NTRS)

The focus of the National Aeronautics and Space Administration's (NASA) Radioisotope Power Systems (RPS) Development program is aimed at developing nuclear power and technologies that would improve the effectiveness of space science missions. The Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) is an important mechanism through which research and technology activities are supported in the Advanced Power Conversion Research and Technology project of the Advanced Radioisotope Power Systems Development program. The purpose of the RPCT NRA is to advance the development of radioisotope power conversion technologies to provide higher efficiencies and specific powers than existing systems. These advances would enable a factor of two to four decrease in the amount of fuel and a reduction of waste heat required to generate electrical power, and thus could result in more cost effective science missions for NASA. The RPCT NRA selected advanced RPS power conversion technology research and development proposals in the following three areas: innovative RPS power conversion research, RPS power conversion technology development in a nominal 100 W(sub e) scale; and, milliwatt/multi-watt RPS (mWRPS) power conversion research. Ten RPCT NRA contracts were awarded in 2003 in the areas of Brayton, Stirling, thermoelectric (TE), and thermophotovoltaic (TPV) power conversion technologies. This paper will provide an overview of the RPCT NRA, a summary of the power conversion technologies approaches being pursued, and a brief digest of first year accomplishments.

Anderson, David J.

2005-01-01

139

NASA Radioisotope Power Conversion Technology NRA Overview  

NASA Technical Reports Server (NTRS)

The focus of the National Aeronautics and Space Administration s (NASA) Radioisotope Power Systems (RPS) Development program is aimed at developing nuclear power and technologies that would improve the effectiveness of space science missions. The Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) is an important mechanism through which research and technology activities are supported in the Advanced Power Conversion Research and Technology project of the Advanced Radioisotope Power Systems Development program. The purpose of the RPCT NRA is to advance the development of radioisotope power conversion technologies to provide higher efficiencies and specific powers than existing systems. These advances would enable a factor of 2 to 4 decrease in the amount of fuel and a reduction of waste heat required to generate electrical power, and thus could result in more cost effective science missions for NASA. The RPCT NRA selected advanced RPS power conversion technology research and development proposals in the following three areas: innovative RPS power conversion research, RPS power conversion technology development in a nominal 100We scale; and, milliwatt/multi-watt RPS (mWRPS) power conversion research. Ten RPCT NRA contracts were awarded in 2003 in the areas of Brayton, Stirling, thermoelectric (TE), and thermophotovoltaic (TPV) power conversion technologies. This paper will provide an overview of the RPCT NRA, a summary of the power conversion technologies approaches being pursued, and a brief digest of first year accomplishments.

Anderson, David J.

2005-01-01

140

NASA Radioisotope Power Conversion Technology NRA Overview  

NASA Astrophysics Data System (ADS)

The focus of the National Aeronautics and Space Administration's (NASA) Radioisotope Power Systems (RPS) Development program is aimed at developing nuclear power and technologies that would improve the effectiveness of space science missions. The Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) is an important mechanism through which research and technology activities are supported in the Advanced Power Conversion Research and Technology project of the Advanced Radioisotope Power Systems Development program. The purpose of the RPCT NRA is to advance the development of radioisotope power conversion technologies to provide higher efficiencies and specific powers than existing systems. These advances would enable a factor of 2 to 4 decrease in the amount of fuel and a reduction of waste heat required to generate electrical power, and thus could result in more cost effective science missions for NASA. The RPCT NRA selected advanced RPS power conversion technology research and development proposals in the following three areas: innovative RPS power conversion research, RPS power conversion technology development in a nominal 100We scale; and, milliwatt/multi-watt RPS (mWRPS) power conversion research. Ten RPCT NRA contracts were awarded in 2003 in the areas of Brayton, Stirling, thermoelectric (TE), and thermophotovoltaic (TPV) power conversion technologies. This paper will provide an overview of the RPCT NRA, a summary of the power conversion technologies approaches being pursued, and a brief digest of first year accomplishments.

Anderson, David J.

2005-02-01

141

ILLUSTRATIONS OF RADIOISOTOPES--DEFINITIONS AND APPLICATIONS.  

ERIC Educational Resources Information Center

THIS PUBLICATION IS COMPOSED OF OVER 150 PAGES OF BLACK AND WHITE ILLUSTRATIONS DEALING WITH RADIOISOTOPES AND THEIR USES. THESE ILLUSTRATIONS CONSIST OF CHARTS, GRAPHS, AND PICTORIAL REPRESENTATIONS WHICH COULD BE PREPARED AS HANDOUTS, TRANSPARENCIES FOR OVERHEAD PROJECTION, OR WHICH COULD BE USED IN A NUMBER OF OTHER WAYS FOR PRESENTING SUCH…

Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

142

Development of Next Generation Segmented Thermoelectric Radioisotope Power Systems  

NASA Astrophysics Data System (ADS)

Radioisotope thermoelectric generators have been used for space-based applications since 1961 with a total of 22 space missions that have successfully used RTGs for electrical power production. The key advantages of radioisotope thermoelectric generators (RTGs) are their long life, robustness, compact size, and high reliability. Thermoelectric converters are easily scalable, and possess a linear current-voltage curve, making power generation easy to control via a shunt regulator and shunt radiator. They produce no noise, vibration or torque during operation. These properties have made RTGs ideally suitable for autonomous missions in the extreme environments of outer space and on planetary surfaces. More advanced radioisotope power systems (RPS) with higher specific power (W/kg) and/or power output are desirable for future NASA missions, including the Europa Geophysical Orbiter mission. For the past few years, the Jet Propulsion Laboratory (JPL) has been developing more efficient thermoelectric materials and has demonstrated significant increases in the conversion efficiency of high temperature thermocouples, up to 14% when operated across a 975K to 300K temperature differential. In collaboration with NASA Glenn Research Center, universities (USC and UNM), Ceramic and Metal Composites Corporation and industrial partners, JPL is now planning to lead the research and development of advanced thermoelectric technology for integration into the next generations of RPS. Preliminary studies indicate that this technology has the potential for improving the RPS specific power by more than 50% over the current state-of-the-art multi-mission RTG being built for the Mars Science Laboratory mission. A second generation advanced RPS is projected at more than doubling the specific power.

Fleurial, J.; Caillat, T.; Ewell, R. C.

2005-12-01

143

Structure of Liquid Boron  

NASA Astrophysics Data System (ADS)

The structure factor S\\(Q\\) and the pair distribution function g\\(r\\) has been measured for liquid boron in the temperature range 2600-2000 K, extending over both the normal and supercooled liquid states. The bond length and coordination number of the first coordination shell are similar to those reported for the crystalline and amorphous solid forms, but the second and third coordination shells are broader and shifted to higher distances. The insulator-metal transition that takes place in boron upon melting is associated with a relatively small change in both volume and short-range order.

Krishnan, S.; Ansell, S.; Felten, J. J.; Volin, K. J.; Price, D. L.

1998-07-01

144

Structure of Liquid Boron  

SciTech Connect

The structure factor S(Q) and the pair distribution function g(r) has been measured for liquid boron in the temperature range 2600{endash}2000thinspthinspK, extending over both the normal and supercooled liquid states. The bond length and coordination number of the first coordination shell are similar to those reported for the crystalline and amorphous solid forms, but the second and third coordination shells are broader and shifted to higher distances. The insulator-metal transition that takes place in boron upon melting is associated with a relatively small change in both volume and short-range order. {copyright} {ital 1998} {ital The American Physical Society}

Krishnan, S.; Felten, J.J. [Containerless Research, Inc., 906 University Place, Evanston, Illinois 60201 (United States)] [Containerless Research, Inc., 906 University Place, Evanston, Illinois 60201 (United States); Ansell, S.; Volin, K.J.; Price, D.L. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

1998-07-01

145

Boron Requirement in Cyanobacteria 1  

PubMed Central

The effect of boron on heterocystous and nonheterocystous dinitrogen fixing Cyanobacteria was examined. The absence of boron in culture media inhibited growth and nitrogenase activity in Nodularia sp., Chlorogloeopsis sp., and Nostoc sp. cultures. Examinations of boron-deficient cultures showed changes in heterocyst morphology. However, cultures of nonheterocystous Cyanobacteria, Gloeothece sp. and Plectonema sp., grown in the absence of boron did not show any alteration in growth or nitrogenase activity. These results suggest a requirement of boron only by heterocystous Cyanobacteria. A possible role for this element in the early evolution of photosynthetic organisms is proposed. Images Figure 4 Figure 5 Figure 6 PMID:16667889

Bonilla, Ildefonso; Garcia-Gonzalez, Mercedes; Mateo, Pilar

1990-01-01

146

Electronic structures of boron nanoribbons  

NASA Astrophysics Data System (ADS)

Using first principles calculations, we investigate the electronic properties of boron nanoribbons. The boron nanoribbons are constructed from the stable boron sheet. The bare boron nanoribbons with different edges are metals. The boron nanoribbons with two-hydrogen passivated on the zigzag edges become semiconductors and are more stable than the one-hydrogen passivated ones. The band gaps are within the range of 0.5eV and there is an oscillatory variation in the band gaps with the change of widths due to the even-odd number of nanoribbon widths.

Ding, Yi; Yang, Xiaobao; Ni, Jun

2008-07-01

147

Fabrication of boron sputter targets  

DOEpatents

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.

Makowiecki, Daniel M. (Livermore, CA); McKernan, Mark A. (Livermore, CA)

1995-01-01

148

Fabrication of boron sputter targets  

DOEpatents

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.

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

1995-02-28

149

An Updated Comprehensive Risk Analysis for Radioisotopes Identified of High Risk to National Security in the Event of a Radiological Dispersion Device Scenario  

NASA Astrophysics Data System (ADS)

An updated global survey of radioisotope production and distribution was completed and subjected to a revised "down-selection methodology" to determine those radioisotopes that should be classified as potential national security risks based on availability and key physical characteristics that could be exploited in a hypothetical radiological dispersion device. The potential at-risk radioisotopes then were used in a modeling software suite known as Turbo FRMAC, developed by Sandia National Laboratories, to characterize plausible contamination maps known as Protective Action Guideline Zone Maps. This software also was used to calculate the whole body dose equivalent for exposed individuals based on various dispersion parameters and scenarios. Derived Response Levels then were determined for each radioisotope using: 1) target doses to members of the public provided by the U.S. EPA, and 2) occupational dose limits provided by the U.S. Nuclear Regulatory Commission. The limiting Derived Response Level for each radioisotope also was determined.

Robinson, Alexandra R.

150

Sublimation of Boron.  

National Technical Information Service (NTIS)

Torsion-effusion and mass spectrometric techniques were used to study the vaporization of beta -rhombohedral boron over the temperature range 1823 to 2253 exp 0 K. The pressure-temperature data were fitted by the equation ln P(Pa) = -(66.8 +- 1.4) 10 exp ...

R. W. Mar, R. G. Bedford

1976-01-01

151

Process for microwave sintering boron carbide  

DOEpatents

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.

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

1993-10-12

152

Process for microwave sintering boron carbide  

DOEpatents

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.

Holcombe, Cressie E. (440 Sugarwood Dr., Knoxville, TN 37922); Morrow, Marvin S. (Rte. #3, Box 113, Kingston, TN 37763)

1993-01-01

153

An overview of the Radioisotope Thermoelectric Generator Transporation System Program  

SciTech Connect

Radioisotope Thermoelectric Generators (RTG) convert the heat generated by radioactive decay to electricity using thermocouples. RTGs have a long operating life, are reasonably lightweight, and require little or no maintenance once assembled and tested. These factors make RTGs particularly attractive for use in spacecraft However, because RTGs contain significant quantities of radioactive materials, normally plutonium-238 and its decay products, they must be transported in packages built in accordance with Title 10, Code of Federal Regulations, Part 71. The US Department of Energy assigned the Radioisotope Thermoelectric Generator Transportation System (RTGTS) Program to Westinghouse Hanford Company in 1988 to develop a system meeting the regulatory requirements. The program objective was to develop a transportation system that would fully comply with 10 CFR 71 while protecting RTGs from adverse environmental conditions during normal conditions of transport (e.g., shock and heat). The RTGTS is scheduled for completion in December 1996 and will be available to support the National Aeronautics and Space Administrations Cassini mission to Saturn in October 1997. This paper provides an overview of the RTGTS and discusses the hardware being produced. Additionally, various program management innovations mandated by recent ma or changes in the US Department of Energy structure and resources will be outlined.

McCoy, J.C.

1995-10-01

154

The use of boron for thermochemical storage and distribution of solar energy  

Microsoft Academic Search

Boron has been proposed as a candidate for hydrogen production. In this study a process is described in which boron is used as a means to store and transport solar energy from a production site to motor vehicles, where it is used to generate hydrogen and heat. The proposed multi-step fuel cycle includes no carbon as a reducing agent and,

Tareq Abu-Hamed; Jacob Karni; Michael Epstein

2007-01-01

155

Cholecystectomy and drainage: Ultrasonographic and radioisotopic evaluation  

Microsoft Academic Search

Eighty patients undergoing cholecystectomy were either assigned deliberately (n=30) or randomized (n=50) to drainage (n=38) or nondrainage (n=42). Subhepatic collections were seen on ultrasonography (US) after 48 to 72 hours in 12 of 35 patients with drainage and 24 of 42 patients without drainage (ppp<0.05). Cholecystectomy was then performed in 100 patients without using a drain. BULIDA radioisotope scans revealed

Vinay K. Kapoor; Mohammad Ibrarullah; Sanjay S. Baijal; Akhilesh Kulshreshtha; Bhagwant R. Mittal; Rajan Saxena; Birendra K. Das; Satyendra P. Kaushik

1993-01-01

156

Microfabricated radioisotope-powered active RFID transponder  

Microsoft Academic Search

We demonstrate a microfabricated 63Ni radioisotope-powered RFID transponder realized with a SAW (surface acoustic wave) device as the transmission frequency selector. The transponder is powered by a 1.5 milli-Ci 63Ni source which has a half-life of 100 years. We have achieved a 5mW, 10-¿s long, 100MHz carrier envelope, RF pulses which occur every 3 minutes, across a 50¿ load. The

S. Tin; A. Lal

2009-01-01

157

NEW DIRECTIONS IN RADIOISOTOPE SPECTRUM IDENTIFICATION  

SciTech Connect

Recent studies have found the performance of commercial handheld detectors with automatic RIID software to be less than acceptable. Previously, we have explored approaches rooted in speech processing such as cepstral features and information-theoretic measures. Scientific advances are often made when researchers identify mathematical or physical commonalities between different fields and are able to apply mature techniques or algorithms developed in one field to another field which shares some of the same challenges. The authors of this paper have identified similarities between the unsolved problems faced in gamma-spectroscopy for automated radioisotope identification and the challenges of the much larger body of research in speech processing. Our research has led to a probabilistic framework for describing and solving radioisotope identification problems. Many heuristic approaches to classification in current use, including for radioisotope classification, make implicit probabilistic assumptions which are not clear to the users and, if stated explicitly, might not be considered desirable. Our framework leads to a classification approach with demonstrable improvements using standard feature sets on proof-of-concept simulated and field-collected data.

Salaymeh, S.; Jeffcoat, R.

2010-06-17

158

Boron isotopic compositions of some boron minerals  

NASA Astrophysics Data System (ADS)

Boron minerals that have different structural formulae but are supposed to have the same geologic origin have been collected and analyzed for the 11B /10B isotopic ratio. It has been reconfirmed that minerals of marine origin have higher 11B /10B ratios than those of nonmarine origin. It has been found that the sequence of decreasing 11B /10B values among the minerals with the same geologic origin is; borax, tincal, kernite (Na borates) > ulexite ( Na/Ca borate) > colemanite, iyoite, meyerhofferite (Ca borates). This sequence is explainable on the basis of the difference in crystal structure among the minerals. That is, minerals with higher BO 3/BO 4 ratios, (the ratio of the number of the BO 3 triangle units to the number of the BO 4 tetrahedron units in the structural formula of a mineral) have higher 11B /10B ratios.

Oi, Takao; Nomura, Masao; Musashi, Masaaki; Ossaka, Tomoko; Okamoto, Makoto; Kakihana, Hidetake

1989-12-01

159

Impact of boron dilution accidents on low boron PWR safety  

SciTech Connect

In conventional pressurized water reactor (PWR) designs, soluble boron is used for reactivity control over core fuel cycle. As an inadvertent reduction of the boron concentration during a boron dilution accident could introduce positive reactivity and have a negative impact on PWR safety, design changes to reduce boron concentration in the reactor coolant are of general interest. In the framework of an investigation into the feasibility of low boron design, a PWR core configuration based on fuel with higher gadolinium (Gd) load has been developed which permits to reduce the natural boron concentration at begin of cycle (BOC) to 518 ppm. For the assessment of the potential safety advantages, a boron dilution accident due to small break loss-of-coolant-accident (SBLOCA) has been simulated with the system code ATHLET for two PWR core designs: a low boron design and a standard core design. The results from the comparative analyses showed that the impact of the boron dilution accident on the new PWR design safety is significantly lower in comparison with the standard design. The new reactor design provided at least 4, 4% higher reactivity margin to recriticality during the whole accident which is equivalent to the negative reactivity worth of additional 63% of all control rods fully inserted in to the core. (authors)

Papukchiev, A.; Liu, Y. [Dept. of Reactor Dynamics and Reactor Safety, Technical Univ. Munich, Walther Meissner-Str. 2, 85748 Garching (Germany); Schaefer, A. [ISaR Inst. for Safety and Reliability, Walther Meissner-Str. 2, 85748 Garching (Germany)

2006-07-01

160

Boron: elementary challenge for experimenters and theoreticians.  

PubMed

Many of the fundamental questions regarding the solid-state chemistry of boron are still unsolved, more than 200 years after its discovery. Recently, theoretical work on the existence and stability of known and new modifications of the element combined with high-pressure and high-temperature experiments have revealed new aspects. A lot has also happened over the last few years in the field of reactions between boron and main group elements. Binary compounds such as B(6)O, MgB(2), LiB(1-x), Na(3)B(20), and CaB(6) have caused much excitement, but the electron-precise, colorless boride carbides Li(2)B(12)C(2), LiB(13)C(2), and MgB(12)C(2) as well as the graphite analogue BeB(2)C(2) also deserve special attention. Physical properties such as hardness, superconductivity, neutron scattering length, and thermoelectricity have also made boron-rich compounds attractive to materials research and for applications. The greatest challenges to boron chemistry, however, are still the synthesis of monophasic products in macroscopic quantities and in the form of single crystals, the unequivocal identification and determination of crystal structures, and a thorough understanding of their electronic situation. Linked polyhedra are the dominating structural elements of the boron-rich compounds of the main group elements. In many cases, their structures can be derived from those that have been assigned to modifications of the element. Again, even these require a critical revision and discussion. PMID:19830749

Albert, Barbara; Hillebrecht, Harald

2009-01-01

161

Radioisotope Thin-Film Fueled Microfabricated Reciprocating Electromechanical Power Generator  

Microsoft Academic Search

A radioisotope power generator with a potential lifetime of decades is demonstrated by employing a 100.3-year half-lifetime 63Ni radioisotope thin-film source to electrostatically actuate and cause reciprocation in a microfabricated piezoelectric unimorph cantilever. The radioisotope direct-charged electrostatic actuation of the piezoelectric unimorph cantilever results in the conversion of radiation energy into mechanical energy stored in the strained unimorph cantilever. The

Rajesh Duggirala; Ronald G. Polcawich; Madan Dubey; Amit Lal

2008-01-01

162

Medical Radioisotope Data Survey: 2002 Preliminary Results  

SciTech Connect

A limited, but accurate amount of detailed information about the radioactive isotopes used in the U.S. for medical procedures was collected from a local hospital and from a recent report on the U.S. Radiopharmaceutical Markets. These data included the total number of procedures, the specific types of procedures, the specific radioisotopes used in these procedures, and the dosage administered per procedure. The information from these sources was compiled, assessed, pruned, and then merged into a single, comprehensive and consistent set of results presented in this report. (PIET-43471-TM-197)

Siciliano, Edward R.

2004-06-23

163

Radioisotope microbattery based on liquid semiconductor  

NASA Astrophysics Data System (ADS)

A liquid semiconductor-based radioisotope micropower source has been pioneerly developed. The semiconductor property of selenium was utilized along with a 166 MBq radioactive source of S35 as elemental sulfur. Using a liquid semiconductor-based Schottky diode, electrical power was distinctively generated from the radioactive source. Energetic beta radiations in the liquid semiconductor can produce numerous electron hole pairs and create a potential drop. The measured power from the microbattery is 16.2 nW with an open-circuit voltage of 899 mV and a short-circuit of 107.4 nA.

Wacharasindhu, T.; Kwon, J. W.; Meier, D. E.; Robertson, J. D.

2009-07-01

164

Boron Clusters Come of Age  

ERIC Educational Resources Information Center

Boron is the only element other than carbon that can build molecules of unlimited size by covalently boding to itself, a property known as catenation. In contrast to the chains and rings favored by carbon, boron arguably adopts a cluster motif that is reflected in the various forms of the pure element and in the huge area of polyhedral borane…

Grimes, Russell N.

2004-01-01

165

Boron-doped graphene and boron-doped diamond electrodes: detection of biomarkers and resistance to fouling.  

PubMed

Doped carbon materials are of high interest as doping can change their properties. Here we wish to contrast the electrochemical behaviour of two carbon allotropes - sp(3) hybridized carbon as diamond and sp(2) hybridized carbon as graphene - doped by boron. We show that even though both materials exhibit similar heterogeneous electron transfer towards ferro/ferricyanide, there are dramatic differences towards the oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine and ?-nicotinamide adenine dinucleotide (NADH). The boron-doped graphene exhibits much lower oxidation potentials than boron-doped diamond. The stability of the surfaces towards NADH oxidation product fouling has been studied and in the long term, there is no significant difference among the studied materials. The proton/electron coupled reduction of dopamine and nitroaromatic explosive (TNT) takes place on boron-doped graphene, while it is not observable at boron-doped diamond. These findings show that boron-doped sp(2) graphene and sp(3) diamond behave, in many aspects, dramatically differently and this shall have a profound influence upon their applicability as electrochemical materials. PMID:23817573

Tan, Shu Min; Poh, Hwee Ling; Sofer, Zden?k; Pumera, Martin

2013-09-01

166

NASA Radioisotope Power Systems Program Update  

NASA Astrophysics Data System (ADS)

The use of Radioisotope Power Systems (RPS) represents a critical capability for exploration of the Solar System. RPS have been used for decades to power deep space missions and sometimes for the operation of landers or rovers on Mars. Modest power needs (<~1 KWe) for regions relatively far from the Sun (~>5 AU) make them attractive, and, in most cases, essential for a variety of missions. Even close by, such as on the surface of the Moon or Mars, RPS enhances operational capability. NASA's strategic planning now contemplates more ambitious missions than those of the past, with the likelihood of increasingly severe or more diverse environments in which to contend. We are at a crossroads in the application of radioisotope power, thanks partially to progress made, but also due to the realities of budget constraints and the availability of plutonium-238 fuel. Within a few years, investments in power conversion technologies could yield next generation flight systems with capability for multiple environments, and improved efficiency and specific power. However, for RPS, given the demands on reliability and system longevity (15+years), infusion of any new RPS technology is the challenge. We review progress made during the past year in development of RPS and note applications in NASA's Science Plan (2007).

Harmon, B. Alan; Lavery, David B.

2008-01-01

167

Reliability Issues in Stirling Radioisotope Power Systems  

NASA Technical Reports Server (NTRS)

Stirling power conversion is a potential candidate for use in a Radioisotope Power System (RPS) for space science missions because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced requirement of radioactive material. Reliability of an RPS that utilizes Stirling power conversion technology is important in order to ascertain long term successful performance. Owing to long life time requirement (14 years), it is difficult to perform long-term tests that encompass all the uncertainties involved in the design variables of components and subsystems comprising the RPS. The requirement for uninterrupted performance reliability and related issues are discussed, and some of the critical areas of concern are identified. An overview of the current on-going efforts to understand component life, design variables at the component and system levels, and related sources and nature of uncertainties are also discussed. Current status of the 110 watt Stirling Radioisotope Generator (SRG110) reliability efforts is described. Additionally, an approach showing the use of past experience on other successfully used power systems to develop a reliability plan for the SRG110 design is outlined.

Schreiber, Jeffrey; Shah, Ashwin

2005-01-01

168

Rhenium Radioisotopes for Therapeutic Radiopharmaceutical Development  

SciTech Connect

The availability of therapeutic radioisotopes at reasonable costs is important for applications in nuclear medicine, oncology and interventional cardiology, Rhenium-186 (Re-186) and rhenium-1 88 (Re-188) are two reactor-produced radioisotope which are attractive for a variety of therapeutic applications, Rhenium-186 has a half-life of 90 hours and decays with emission of a &particle with a maximum energy of 1.08 MeV and a 135 keV (9Yo) gamma which permits imaging. In contrast, Re- 188 has a much shorter half-life of 16.9 hours and emits a p-particle with a much higher energy of 2.12 MeV (Em=) and a 155 keV gamma photon (15Yo) for imaging. While Re-186 is unavailable from a generator system and must be directly produced in a nuclear reactor, Re-188 can also be directly produced in a reactor with high specific activity, but is more conveniently and cost-effectively available as carrier-free sodium perrhenate by saline elution of the alumina-based tungsten-188 (W1 88)/Re-l 88 generator system [1-2]. Since a comprehensive overviewofRe-186 and Re-188 therapeutic agents is beyond the scope of this &tended Abstrac4 the goal is to provide key examples of various agents currently in clinical use and those which are being developed for important clinical applications.

Beets, A.L.; Knapp, F.F., Jr.; Kropp, J.; Lin, W.-Y.; Pinkert, J.; Wang, S.-Y.

1999-01-18

169

Multi-mission radioisotope thermoelectric generator (MMRTG) program overview  

Microsoft Academic Search

Future NASA missions require safe, reliable, long-lived power systems for surface exploration of planetary bodies such as Mars as well as exploration of the solar system in the vacuum of space beyond Earth orbit. To address this need, the Department of Energy and NASA have initiated the development of radioisotope power systems, including the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). In

Fred Ritz; C. E. Peterson

2004-01-01

170

Boron Neutron Capture Therapy for Cancer  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) bring together two components that when kept separate have only minor effects on normal cells. The first component is a stable isotope of boron (boron 10) that can be concentrated in tumor cells. The second is a beam of low-energy neutrons that produces short-range radiation when absorbed, or captured, by the boron. The combination of

Rolf F. Barth; Albert H. Soloway; Ralph G. Fairchild

1990-01-01

171

Electrochemical incineration of omeprazole in neutral aqueous medium using a platinum or boron-doped diamond anode: degradation kinetics and oxidation products.  

PubMed

The electrochemical incineration of omeprazole, a widely prescribed gastrointestinal drug which is detected in natural waters, has been studied in a phosphate buffer of pH 7.0 by anodic oxidation with electrogenerated H(2)O(2) (AO-H(2)O(2)) operating at constant current density (j). The experiments were carried out in a cell equipped with either a Pt or a boron-doped diamond (BDD) anode and an air-diffusion cathode to continuously produce H(2)O(2). In these systems, organics are mainly oxidized by hydroxyl radicals formed at the Pt or BDD surface from water oxidation. A partial total organic carbon (TOC) abatement close to 78% for omeprazole was achieved by AO-H(2)O(2) with a BDD anode after consumption of 18 Ah L(-1) at 100 mA cm(-2), whereas the alternative use of Pt did not allow mineralizing the drug. However, the drug was totally removed using both anodes, although it decayed more rapidly using BDD. In this latter system, increasing j accelerated the degradation process, but lowering the mineralization current efficiency. Greater drug content also enhanced the degradation rate with higher mineralization degree and current efficiency. The kinetics for omeprazole decay always followed a pseudo-first-order reaction and its rate constant increased with increasing j and with decreasing its concentration. Seven heteroaromatic intermediates and four hydroxylated derivatives were detected by LC-MS, while nine short-linear carboxylic acids were identified and quantified by ion-exclusion HPLC. These acids were largely accumulated using Pt and rapidly removed using BDD, thus explaining the partial mineralization of omeprazole achieved by AO-H(2)O(2) with the latter anode. The release of inorganic ions such as NO(3)(-), NH(4)(+) and SO(4)(2-) was followed by ionic chromatography. A plausible reaction sequence for omeprazole mineralization involving all intermediates detected is proposed. PMID:23351432

Cavalcanti, Eliane Bezerra; Garcia-Segura, Sergi; Centellas, Francesc; Brillas, Enric

2013-04-01

172

Sulfonate pseudohalides of boron subphthalocyanine.  

PubMed

The crystal structures of three sulfonate pseudohalide derivatives of boron subphthalocyanine (BsubPc) are described and compared with four structures of three published sulfonate derivatives. Benzenesulfonate boron subphthalocyanine [(benzenesulfonato)(subphthalocyaninato)boron, C(30)H(17)BN(6)O(3)S, (I)] crystallizes in the space group P-1 with Z = 2. The structure contains two centrosymmetric ?-stacking interactions between the concave faces of the isoindoline units in the BsubPc ligands. 3-Nitrobenzenesulfonate boron subphthalocyanine [(3-nitrobenzenesulfonato)(subphthalocyaninato)boron, C(30)H(16)BN(7)O(5)S, (II)] crystallizes in the space group P2(1)/c with Z = 4. The structure contains an intermolecular S-O···? interaction from the sulfonate group to a five-membered N-containing ring of an isoindoline unit on the concave side of a neighbouring BsubPc ligand, at a distance of 3.151 (3) Å. The crystal of methanesulfonate boron subphthalocyanine [(methanesulfonato)(subphthalocyaninato)boron, C(25)H(15)BN(6)O(3)S, (III)] was produced via sublimation and it is not a solvate, in contrast with two previously published structures of the same compound. Compound (III) crystallizes in the space group P2(1)/n with Z = 2, and its structure is similar to that of the more common compound Cl-BsubPc. PMID:23124463

Paton, Andrew S; Lough, Alan J; Bender, Timothy P

2012-11-01

173

Phosphorus Use-Efficiency by Cotton Grown in an Alkaline Soil as Determined Using Phosphorus and Phosphorus Radio-Isotopes  

Microsoft Academic Search

Phosphorus (P) and P radioisotopes were used to identify the contribution of soil and fertilizer P sources to P uptake by cotton (Gossypium hirsutum L.) grown in an alkaline soil representative of those used for growing cotton in Australia. Phosphorus fertilizer application only increased P concentration in the plants during leaf expansion, but had no effect on biomass production, P

Christopher G. Dorahy; Ian J. Rochester; Graeme J. Blair; A. Raymond Till

2008-01-01

174

INFLUENCE OF BORON ON PRE AND POST IRRADIATION PROPERTIES OF TYPE 304 STAINLESS STEEL AND WELD METAL  

Microsoft Academic Search

Experimental heats of 2 wt% natural boron modified Type 304 stainless ; steel incorporating scrap from a commercial heat of the alloy, which failed to ; convert to sheet product, established the necessity of maintaining minimum ; manganese and silicon contents. When chemical composition is controlled, boron ; containing Type 304 stainless steels can be converted to sheet products which

N. Balai; L. C. Hymes

1960-01-01

175

Radioisotope detection and dating with accelerators  

NASA Astrophysics Data System (ADS)

Recent developments in mass spectrometry have made possible the direct detection of many naturally occurring long-lived radioisotopes. Radioactive atoms are present at such low concentrations that the sensitivity of the mass spectrometry has to be increased to detect parts per quadrillion (1015) in a sample. This sensitivity has been achieved, and some of the results taken at Rochester by the Rochester (University), Toronto (University), General Ionex (Corporation) collaboration are listed in the table. All the radioactive isotopes listed in the table are of importance in geochronology, and for 14C and 36C1, sensitivities better than parts per quadrillion (1015) have already been reached. Early work on the stable isotopes of platinum has already reached below parts per billion (109).

Litherland, A. E.; Rucklidge, J. C.

176

Status of the NASA Stirling Radioisotope Project  

NASA Technical Reports Server (NTRS)

Free-piston Stirling power conversion has been considered a candidate for radioisotope power systems for space for more than a decade. Prior to the free-piston Stirling architecture, systems were designed with kinematic Stirling engines that used linkages and rotary alternators to convert heat to electricity. These systems were able to achieve long life by lightly loading the linkages; however, the live was nonetheless limited. When the free-piston configuration was initially proposed, it was thought to be attractive due to the relatively high conversion efficiency, acceptable mass, and the potential for long life and high reliability based on wear-free operation. These features have consistently been recognized by teams that have studied technology options for radioisotope space power systems. Since free-piston Stirling power conversion was first considered for space power applications, there have been major advances in three general areas of development: hardware that has demonstrated long-life and reliability, the success achieved by Stirling cryocoolers in space, and the overall developmental maturity of the technology for both space and terrestrial applications. Based on these advances, free-piston Stirling convertors are currently being developed for space power, and for a number of terrestrial applications. They commonly operate with the power, efficiency, life, and reliability as intended, and much of the development now centers on system integration. This paper will summarize the accomplishments of free-piston Stirling power conversion technology over the past decade, review the status of development with regard to space power, and discuss the challenges that remain.

Schreiber, Jeffrey G.

2007-01-01

177

Current and potential therapeutic uses of lanthanide radioisotopes.  

PubMed

In the last 25 years, diagnostic nuclear medicine has come to depend on the versatile chemistry of a single radioisotope, technetium-99m (Tc-99m). Different chelating molecules can be used to guide Tc-99m through various physiological pathways in the body to gain information about disease states. No single radioisotope similarly dominates therapeutic applications. In the field of radioisotope therapy, much discussion and debate have focused on what radioisotope might be "ideal" for treatment of malignant tumors. The ideal may not be a single radioisotope, but rather the class of very closely related radiolanthanides and lanthanide-like radioisotopes. These radioisotopes possess strikingly similar chemistries and thus all may be conjugated to biomolecules using a single chelate, the DOTA moiety (and its chemical analogs). They also provide a wide range of physical characteristics, such as half-lives and beta energies, that can be chosen to match the biological properties of the conjugated biomolecule and the malignant tumor. Thus, the radiolanthanide-DOTA bioconjugate model provides a set of physically diverse, but chemically very similar, therapeutic radiopharmaceutical agents, the individual members of which can be tailored to treat specific types of cancers. PMID:11190486

Cutler, C S; Smith, C J; Ehrhardt, G J; Tyler, T T; Jurisson, S S; Deutsch, E

2000-12-01

178

General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

This research investigates the use of a PETtrace cyclotron produced by General Electric (GE) as a neutron source for boron neutron capture therapy (BNCT). The GE PETtrace was chosen for this investigation because this type of cyclotron is popular among nuclear pharmacies and clinics in many countries; it is compact and reliable; it produces protons with energies high enough to produce neutrons with appropriate energy and fluence rate for BNCT and it does not require significant changes in design to provide neutrons. In particular, the standard PETtrace 18O target is considered. The cyclotron efficiency may be significantly increased if unused neutrons produced during radioisotopes production could be utilized for other medical modalities such as BNCT at the same time. The resulting dose from the radiation emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at several depths in a brain phantom for different scattering geometries. Four different moderating materials of various thicknesses were considered: light water, carbon, heavy water, arid Fluental(TM). The fluence rate tally was used to calculate photon and neutron dose, by applying fluence rate-to-dose conversion factors. Fifteen different geometries were considered and a 30-cm thick heavy water moderator was chosen as the most suitable for BNCT with the GE PETtrace cyclotron. According to the Brookhaven Medical Research Reactor (BMRR) protocol, the maximum dose to the normal brain is set to 12.5 RBEGy, which for the conditions of using a heavy water moderator, assuming a 60 muA beam current, would be reached with a treatment time of 258 min. Results showed that using a PETtrace cyclotron in this configuration provides a therapeutic ratio of about 2.4 for depths up to 4 cm inside a brain phantom. Further increase of beam current proposed by GE should significantly improve the beam quality or the treatment time and allow treating tumors at greater depths.

Bosko, Andrey

179

BORON SYNTHESIS IN TYPE Ic SUPERNOVAE  

SciTech Connect

We investigate the {nu}-process in an energetic Type Ic supernova (SN Ic) and the resultant productions of the light elements including boron and its stable isotopes. SN Ic is a very unique boron source because it can produce boron not only through spallation reactions as discussed in Nakamura and Shigeyama but also the {nu}-process. The {nu}-process is considered to occur in core-collapse supernovae and previous studies were limited to SNe II. Although the progenitor star of an SN Ic does not posses an He envelope so that {sup 7}Li production via the {nu}-process is unlikely, {sup 11}B can be produced in the C-rich layers. We demonstrate a hydrodynamic simulation of a SN Ic explosion and estimate the amounts of the light elements produced via the {nu}-process for the first time, and also the subsequent spallation reactions between the outermost layers of the compact SN Ic progenitor and the ambient medium. We find that the {nu}-process in the current SN Ic model produces a significant amount of {sup 11}B, which is diluted by {sup 10}B from spallation reactions to get closer to B isotopic ratios observed in meteorites. We also confirm that high-temperature {mu} and {tau} neutrinos and their anti-neutrinos, reasonably suggested from the compact structure of SN Ic progenitors, enhance the light-element production through the neutral current reactions, which may imply an important role of SNe Ic in the Galactic chemical evolution.

Nakamura, Ko; Kajino, Toshitaka [National Astronomical Observatory of Japan, Mitaka, Tokyo (Japan); Yoshida, Takashi; Shigeyama, Toshikazu [Department of Astronomy, Graduate School of Science, University of Tokyo, Tokyo (Japan)

2010-08-01

180

Boron Isotopic Compositions of Near-Surface Fluids: A Tracer for Identification of Natural and Anthropogenic Contaminant Sources  

Microsoft Academic Search

Boron (B) is a sensitive stable isotope tracer which allows identification of different anthropogenic contaminant sources, originating from man-made boron products manufactured from non-marine borates (d11B = +10‰), in near-surface fluids which are characterized by a different natural background signature of predominantly meteoric origin. The data presented show that the boron isotopic composition of uncontaminated groundwater at the study site

S. R. Barth

2000-01-01

181

Report on audit of funding for advanced radioisotope power systems  

SciTech Connect

The U.S. Department of Energy`s (Department) Advanced Radioisotope Power Systems Program maintains the sole national capability and facilities to produce radioisotope power systems for the National Aeronautics and Space Administration (NASA), the Department of Defense, and other Federal agencies. Projects are conducted with these agencies in accordance with written agreements and are dependent on cost sharing by the user agencies. For the past seven years the program emphasis has been on providing power systems for NASA`s Cassini mission to Saturn, which was launched earlier this month. We initiated this audit to determine whether the Department received proper reimbursement from NASA for the radioisotope power systems produced.

NONE

1997-10-17

182

Boron isotope application for tracing sources of contamination in groundwater.  

E-print Network

Boron isotope application for tracing sources of contamination in groundwater. Abstract: Boron isotope composition and concentration of sewage effluent and pristine and contaminated groundwater from. Anthropogenic boron in wastewater is isotopically distinct from natural boron in groundwater and thus can

Kasher, Roni

183

Neutron detectors comprising boron powder  

DOEpatents

High-efficiency neutron detector substrate assemblies comprising a first conductive substrate, wherein a first side of the substrate is in direct contact with a first layer of a powder material comprising .sup.10boron, .sup.10boron carbide or combinations thereof, and wherein a conductive material is in proximity to the first layer of powder material; and processes of making said neutron detector substrate assemblies.

Wang, Zhehui; Morris, Christopher; Bacon, Jeffrey Darnell; Makela, Mark F; Spaulding, Randy Jay

2013-05-21

184

Molecular Structure of Boron trifluoride  

NSDL National Science Digital Library

Boron trifluoride has a trigonal pryamidal shape and dissolves in diethyl ether. Normally a gas, boron trifluoride is a hard and strong Lewis acid with a high affinity in displacement reactions and is therefore used mainly as a catalyst in alkylations, polymerizations and esterifications. It extracts bases bound to carbon and produces carbocations. Also it is used as a fumigant and in the magnesium industry because its anti-oxidant properties.

2002-08-15

185

Boron diffusion in silicon devices  

DOEpatents

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

Rohatgi, Ajeet (Atlanta, GA); Kim, Dong Seop (Atlanta, GA); Nakayashiki, Kenta (Smyrna, GA); Rounsaville, Brian (Stockbridge, GA)

2010-09-07

186

Electrochemical oxidation of benzene on boron-doped diamond electrodes  

Microsoft Academic Search

This work presents an electrochemical investigation of the benzene oxidation process in aqueous solution on boron-doped diamond (BDD) electrodes. Additionally, in order to determine the main products generated during the oxidation process, electrolysis and high performance liquid chromatography experiments were carried out. The complete degradation of this compound was performed aiming to a further application in waste water treatment. The

Robson T. S. Oliveira; Giancarlo R. Salazar-Banda; Mauro C. Santos; Marcelo L. Calegaro; Douglas W. Miwa; Sergio A. S. Machado; Luis A. Avaca

2007-01-01

187

Microdosimetric evaluations of boron compound efficacy  

SciTech Connect

The ideal boron compound for application in boron neutron capture therapy (BNCT) should be selectively accumulated in tumor with concomitantly low concentrations in neighboring normal tissues and blood. As the presumed target of lethal radiation is the nucleus, an intracellular and, optimally, intranuclear localization of boron would be preferred. Boronated nucleosides, nucleotides, and DNA-intercalators have been synthesized in pursuit of this goal. This paper describes an approach to predict the relative biological effectiveness (RBE) values for such boron compounds. The results of this study may prove useful for future boron compound development for BNCT.

Yam, C.S. [Massschusets Institute of Technology, Cambridge, MA (United States); Zamenhof, R.G.; Solares, G.R. [Tufts New England Medical Center, Boston, MA (United States)

1995-12-31

188

Magnetron sputtered boron films for increasing hardness of a metal surface  

DOEpatents

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.

Makowiecki, Daniel M. (Livermore, CA); Jankowski, Alan F. (Livermore, CA)

2003-05-27

189

Azomethine H colorimetric method for determining dissolved boron in water  

USGS Publications Warehouse

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.

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

1979-01-01

190

A power conditioning system for radioisotope thermoelectric generator energy sources  

NASA Technical Reports Server (NTRS)

The use of radioisotope thermoelectric generators (RTG) as the primary source of energy in unmanned spacecraft is discussed. RTG output control, power conditioning system requirements, the electrical design, and circuit performance are also discussed.

Gillis, J. A., Jr.

1974-01-01

191

Synthesis and characterization of coordination polymer nanoparticles as radioisotope tracers.  

PubMed

Coordination polymer nanoparticles (NPs) with gamma-emitting nuclide (Au-198), 411keV, 675keV, 822keV and 1087keV were prepared by coordination polymerization of the radioisotope Au(3+) ions and 1,4-bis(imidazole-1-ylmethyl)benzene in an aqueous solution at room temperature for 3h. Here, the radioisotope Au(3+) ions were prepared by dissolution of Au-198 foil, which was prepared by neutron irradiation from the HANARO reactor, in KCN aqueous solution. The successful synthesis of the radioisotope coordination polymer NPs with 5±0.5nm was confirmed via UV-vis spectroscopy, Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectrometry (EDXS), Thermogravimetric analysis (TGA), and Gamma spectroscopy analysis. The synthesized radioisotope coordination polymer NPs can be used as radiotracers in science, engineering, and industrial fields. PMID:24362459

Oh, Min-Seok; Jung, Sung-Hee; Choi, Seong-Ho

2014-02-01

192

Determining Molar Combining Ratios Using Radioisotopes--A Student Experiment  

ERIC Educational Resources Information Center

Outlines an experimental procedure in which an iodine radioisotope is used to determine molar combining ratios of lead and silver with the iodine. Tables and graphs show the definitive results that should be attainable. (CP)

Sears, Jerry A.

1976-01-01

193

ClusterBoron Implant Alternative to BF{sub 2} PMOS SDE  

SciTech Connect

As device geometries scale, the formation of the SDE becomes increasingly difficult and increasingly important. For advanced technologies, new methods such as ultra-low-energy boron implantation and millisecond annealing (flash or laser) are necessary to achieve the required junction characteristics. In addition, these processes must be compatible with the remainder of the process flow, which might include advanced dielectrics, stress technologies, SOI, etc. The emergence of ClusterBoron as a high productivity alternative for the low energy implant creates interest in device performance possible in a realistic process flow. This paper will present an evaluation of the use of ClusterBoron for the PMOS SDE in an advanced 65 nm logic process which includes laser annealing, e-SiGe stress layers and SOI. The conventional process uses a BF2 SDE process. Complete device characteristics will be shown comparing the ClusterBoron SDE to the conventional BF2. It will be shown that the ClusterBoron process achieves better boron activation, leading to enhanced transistor drive current. It will also be shown that the ClusterBoron is compatible with the SiGe stress layers and SOI structure. In summary, ClusterBoron presents an attractive alternative to the conventional BF2 process for advanced PMOS SDE.

Feudel, Thomas; Illgen, Ralf; Krueger, Christian; Braun, Marek [AMD Saxony, LLC and Co. KG, Wilschdorfer Landstr 101, D01109 Dresden (Germany); Sekar, Karuppanan; Lee, David; Krull, Wade [SemEquip, Inc., 34 Sullivan Road, North Billerica, Massachusetts 01862 (United States)

2008-11-03

194

The boron efflux transporter ROTTEN EAR is required for maize inflorescence development and fertility.  

PubMed

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

Chatterjee, Mithu; Tabi, Zara; Galli, Mary; Malcomber, Simon; Buck, Amy; Muszynski, Michael; Gallavotti, Andrea

2014-07-01

195

Automated radioisotope identification using fuzzy logic and portable CZT detectors  

Microsoft Academic Search

Automated in-field radioisotope identification presents many challenges, including difficult choices in detector technology, the need for high-reliability low-power electronics, and imprecise analysis methods. To meet these challenges, we have developed ruggedized large-volume CdZnTe (CZT) detectors that are coupled to state-of-the-art low-power electronics to perform radioisotope identification with fuzzy logic in real time. The analysis is presented in a simple straightforward

W. S. Murray; K. B. Butterfield; W. Baird

2000-01-01

196

CMOS compatible Multiple Power-Output MEMS Radioisotope ?-Power Generator  

Microsoft Academic Search

The authors demonstrate a novel 6.6% high-efficiency CMOS compatible piezoelectric aluminum nitride (AlN) thin-film based integrated ?-radioisotope-powered electro-mechanical power generator (IREMPG). the authors integrate silicon betavoltaics with radioisotope actuated piezoelectric unimorph converters to efficiently utilize both kinetic energy and charge of the emitted beta particles for electrical power generation. IREMPG has three output ports generating (1) a 2.8MHz pulse remotely

Rajesh Duggirala; A. Lai; Ronald G. Polcawich; Madan Dubey

2006-01-01

197

Synthesis and photocurrent of amorphous boron nanowires  

NASA Astrophysics Data System (ADS)

Although theoretically feasible, synthesis of boron nanostructures is challenging due to the highly reactive nature, high melting and boiling points of boron. We have developed a thermal vapor transfer approach to synthesizing amorphous boron nanowire using a solid boron source. The amorphous nature and chemical composition of boron nanowires were characterized by high resolution transmission electron microscopy, selected area electron diffraction, and electron energy loss spectroscopy. Optical properties and photoconduction of boron nanowires have not yet been reported. In our investigation, the amorphous boron nanowire showed much better optical and electrical properties than previously reported photo-response of crystalline boron nanobelts. When excited by a blue LED, the photo/dark current ratio (I/I0) is 1.5 and time constants in the order of tens of seconds. I/I0 is 1.17 using a green light.

Ge, Liehui; Lei, Sidong; Hart, Amelia H. C.; Gao, Guanhui; Jafry, Huma; Vajtai, Robert; Ajayan, Pulickel M.

2014-08-01

198

Boronated porhyrins and methods for their use  

DOEpatents

The present invention covers boronated porphyrins containing multiple carborane cages which selectively accumulate in neoplastic tissue within the irradiation volume and thus can be used in cancer therapies such as boron neutron capture therapy and photodynamic therapy.

Miura, Michiko (Hampton Bays, NY); Shelnutt, John A. (Tijeras, NM); Slatkin, Daniel N. (Southhold, NY)

1999-03-02

199

Boronated porhyrins and methods for their use  

DOEpatents

The present invention covers boronated porphyrins containing multiple carborane cages which selectively accumulate in neoplastic tissue within the irradiation volume and thus can be used in cancer therapies such as boron neutron capture therapy and photodynamic therapy. 3 figs.

Miura, M.; Shelnutt, J.A.; Slatkin, D.N.

1999-03-02

200

Radioisotope cisternography in head-injured patients.  

PubMed

Of 600 patients submitted to radioisotope cisternography carried out with radioiodinated human serum albumin (I131-HSA) a group of 140 had head injuries. Our investigation was intended to study the modifications of CSF circulation and absorption which accompany cranio-cerebral trauma. Of 88 head injured patients who did not undergo operation 44 had transient loss of consciouness, and 44 were in prolonged coma. Fifty-two patients underwent operation. Of these 5 had skull fractures with dural lesions, 7 had extradural haematomas, 19 had subdural haematomas, and 21 had brain contusions. Cisternograms were performed at different time intervals after trauma, and in some instances the test was repeated in order to study the possible long tern alterations of CSF circulation and absorption. Abnormalities of cisternographic pictures are classified into the following groups: 1 degree asymmetric diffusion; 2 degree operative cavity stagnation; 3 degree ventricular reflux; 4 degree associated abnormalities. Cisternographic features are analysed in relation to the corresponding clinical and pneumoencephalographic patterns in the patients examined. These investigations may enable us to recognise possible indications for shunt procedures in the management of CSF absorption defects, which are so frequently apparent after head injury. PMID:1163316

Villani, R; Gaini, S M; Paoletti, P; Brambilla, G; Caneschi, S; Frigeni, G

1975-01-01

201

Light-weight radioisotope heater impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s.

Reimus, M.A.H.; Rinehart, G.H.; Herrera, A. [and others

1998-12-31

202

Radioisotope Power Sources for MEMS Devices,  

SciTech Connect

Microelectromechanical systems (MEMS) comprise a rapidly expanding research field with potential applications varying from sensors in airbags to more recent optical applications. Depending on the application, these devices often require an on-board power source for remote operation, especially in cases requiring operation for an extended period of time. Previously suggested power sources include fossil fuels and solar energy, but nuclear power sources may provide significant advantages for certain applications. Hence, the objective of this study is to establish the viability of using radioisotopes to power realistic MEMS devices. A junction-type battery was constructed using silicon and a {sup 63}Ni liquid source. A source volume containing 64 {micro}Ci provided a power of {approx}0.07 nW. A more novel application of nuclear sources for MEMS applications involves the creation of a resonator that is driven by charge collection in a cantilever beam. Preliminary results have established the feasibility of this concept, and future work will optimize the design for various applications.

Blanchard, J.P.

2001-06-17

203

Radioisotope-based Nuclear Power Strategy for Exploration Systems Development  

SciTech Connect

Nuclear power will play an important role in future exploration efforts. Its benefits pertain to practically all the different timeframes associated with the Exploration Vision, from robotic investigation of potential lunar landing sites to long-duration crewed missions on the lunar surface. However, the implementation of nuclear technology must follow a logical progression in capability that meets but does not overwhelm the power requirements for the missions in each exploration timeframe. It is likely that the surface power infrastructure, particularly for early missions, will be distributed in nature. Thus, nuclear sources will have to operate in concert with other types of power and energy storage systems, and must mesh well with the power architectures envisioned for each mission phase. Most importantly, they must demonstrate a clear advantage over other non-nuclear options (e.g., solar power, fuel cells) for their particular function. This paper describes a strategy that does this in the form of three sequential system developments. It begins with use of radioisotope generators currently under development, and applies the power conversion technology developed for these units to the design of a simple, robust reactor power system. The products from these development efforts would eventually serve as the foundation for application of nuclear power systems for exploration of Mars and beyond.

Schmidt, George R.; Houts, Michael G. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2006-01-20

204

Methods for boron delivery to mammalian tissue  

DOEpatents

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.

Hawthorne, M. Frederick (Encino, CA); Feaks, Debra A. (Los Angeles, CA); Shelly, Kenneth J. (Los Angeles, CA)

2003-01-01

205

Mineral resource of the month: boron  

USGS Publications Warehouse

What does boron have to do with baseball, apple pie, motherhood and Chevrolet? Boron minerals and chemicals are used in the tanning of leather baseballs and gloves; in micro-fertilizer to grow apples and in the glass and enamels of bakewares to cook apple pie; in boron detergents for soaking baby clothes and diapers; and in fiberglass parts for the Chevrolet Corvette.

Lyday, Phyllis A.

2005-01-01

206

Development of a radioisotope heat source for the two-watt radioisotope thermoelectric generator  

NASA Astrophysics Data System (ADS)

Described is a radioisotope heat source for the Two-Watt Radioisotope Thermoelectric Generator (RTG) which is being considered for possible application by the U.S. Navy and for other Department of Defense applications. The heat source thermal energy (75 Wt) is produced from the alpha decay of plutonium-238 which is in the form of high-fired plutonium dioxide. The capsule is non-vented and consists of three domed cylindrical components each closed with a corresponding sealed end cap. Surrounding the fuel is the liner component, which is fabricated from a tantalum-based alloy, T-111. Also fabricated from T-111 is the next component, the strength member, which serves to meet pressure and impact criteria. The outermost component, or clad, is the oxidation- and corrosion-resistant nickel-based alloy, Hastelloy S. This paper defines the design considerations, details the hardware fabrication and welding processes, discusses the addition of yttrium to the fuel to reduce liner embrittlement, and describes the testing that has been conducted or is planned to assure that there is fuel containment not only during the heat source operational life, but also in case of an accident environment.

Howell, Edwin I.; McNeil, Dennis C.; Amos, Wayne R.

1992-01-01

207

Boron doping a semiconductor particle  

SciTech Connect

A method of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried, with the boron film then being driven into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out into piles and melted/fused with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements. 2 figs.

Stevens, G.D.; Reynolds, J.S.; Brown, L.K.

1998-06-09

208

Boron doping a semiconductor particle  

DOEpatents

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

Stevens, Gary Don (18912 Ravenglen Ct., Dallas, TX 75287); Reynolds, Jeffrey Scott (703 Horizon, Murphy, TX 75094); Brown, Louanne Kay (2530 Poplar Tr., Garland, TX 75042)

1998-06-09

209

Analogies between boron and carbon.  

PubMed

The structural connections between the compounds of boron and carbon are extended using the mno rule beyond the borane-carbocation continuum, the lithium boride-polycarbyne analogy, and the magnesium boride (MgB(2))-graphite equivalence to beta-rhombohedral boron and fullerenes. The structural similarity of the pentagonal pyramidal C(6)H(6)(2+) and MgB(4) is established. An interesting electronic structural relationship between the B(84) fragment of the beta-rhombohedral boron and the fulleride anion, C(60)(12-), is derived by replacing the 12 pentagonal pyramidal B(6)(4-) units by isoelectronic C(5)(-) units and removing the central B(12) from the electron-deficient B(84) unit. This relationship is well supported by the experimental realization of C(60)M(12) (M = Li, K) and C(48)N(12). PMID:14622028

Jemmis, Eluvathingal D; Jayasree, Elambalassery G

2003-11-01

210

First-Principles Investigation on Boron Nanostructures  

NASA Astrophysics Data System (ADS)

First-principles calculations based on density functional theory are employed to study and predict the properties of boron and Mg boride nanostructures. For boron nanostructures, two-dimensional boron sheets are found to be metallic and made of mixtures of triangles and hexagons which benefit from the balance of two-center bonding and three-center bonding. This unusual bonding in boron sheets results in a self-doping picture where adding atoms to the hexagon centers does not change the number of bonding states but merely increases the electron count. Boron sheets can be either flat or buckled depending on the ratio between hexagons and triangles. Formed by stacking two identical boron sheets, double-layered boron sheets can form interlayer bonds, and the most stable one is semiconducting. Built from single-layered boron sheets, single-walled boron nanotubes have smaller curvature energies than carbon nanotubes and undergo a metal-to-semiconductor transition once the diameter is smaller than ˜20 A. Optimal double-walled boron nanotubes with inter-walled bonds formed are metallic and always more stable than single-walled ones. For Mg boride nanostructures, certain Mg boride sheets prefer to curve themselves into nanotubes, which is explained via Mg-Mg interactions governed by the charge state of Mg. In addition, optimal Mg boride sheet structures are explored with a genetic algorithm. Phase diagrams for Mg boride sheet structures are constructed and stable phases under boron-rich environments are identified. Curvature effects on the phase diagram of Mg boride nanotubes are also discussed. As a natural extension to boron sheets, layered boron crystals based on boron sheets are then presented and are shown to be stable under high pressure. Finally, this thesis ends with an investigation of hydrogen-storage properties of pristine and metal doped boron nanostructures.

Tang, Hui

211

Boron recovery, application and economic significance: A review  

Microsoft Academic Search

Boron compounds are widely used raw materials in various industries. However, high boron concentration in aqueous systems may be harmful to both humans and plants. Many treatment technologies have shown wide limitations in the removal of boron from wastewater and boronic wastes due to the complex boron chemistry. Boron exists as boric acid at pH9.2. Recovery of boron is one

Ezerie Henry Ezechi; Mohamed Hasnain Isa; Shamsul Rahman Kutty; Nasiman B. Sapari

2011-01-01

212

Chemoselective boronic ester synthesis by controlled speciation.  

PubMed

Control of boronic acid solution speciation is presented as a new strategy for the chemoselective synthesis of boronic esters. Manipulation of the solution equilibria within a cross-coupling milieu enables the formal homologation of aryl and alkenyl boronic acid pinacol esters. The generation of a new, reactive boronic ester in the presence of an active palladium catalyst also facilitates streamlined iterative catalytic C?C bond formation and provides a method for the controlled oligomerization of sp(2) -hybridized boronic esters. PMID:25267096

Fyfe, James W B; Seath, Ciaran P; Watson, Allan J B

2014-11-01

213

Evaluation of medical isotope production with the accelerator production of tritium (APT) facility  

SciTech Connect

The accelerator production of tritium (APT) facility, with its high beam current and high beam energy, would be an ideal supplier of radioisotopes for medical research, imaging, and therapy. By-product radioisotopes will be produced in the APT window and target cooling systems and in the tungsten target through spallation, neutron, and proton interactions. High intensity proton fluxes are potentially available at three different energies for the production of proton- rich radioisotopes. Isotope production targets can be inserted into the blanket for production of neutron-rich isotopes. Currently, the major production sources of radioisotopes are either aging or abroad, or both. The use of radionuclides in nuclear medicine is growing and changing, both in terms of the number of nuclear medicine procedures being performed and in the rapidly expanding range of procedures and radioisotopes used. A large and varied demand is forecast, and the APT would be an ideal facility to satisfy that demand.

Benjamin, R.W. [Westinghouse Savannah River Company, Aiken, SC (United States); Frey, G.D.; McLean, D.C., Jr; Spicer, K.M.; Davis, S.E.; Baron, S.; Frysinger, J.R. [Medical Univ. of South Carolina, Charleston, SC (United States); Blanpied, G.; Adcock, D. [South Carolina Univ., Columbia, SC (United States)

1997-07-10

214

[Effect of NPK and B supply levels on boron uptake and biological properties of different genotypic oilseed rape].  

PubMed

Pot experiment was conducted to study the boron absorption by oilseed rape(Brassica napus), the mechanism of its resistance to boron deficiency, and the effect of boron deficiency on its biological properties under different NPK supply levels. The results indicated that under boron deficiency, increasing NPK supply aggravated boron deficiency symptoms, which led to the decrease of leaf area and its growth rate and nitrate reductase activity(NRA) and the increase of chlorophyll(a + b) content at seedling stage, and the decrease of the number of productive branches and pods of each plant and seed yield at maturity. It was suggested that the ratio of boron concentration in youngest open leaves(YOL) to youngest mature leaves(YML) at seedling stage could be an index to judge the boron mobility in plants of different genotypic oilseed rape. Boron mobility and its utilization efficiency were one of the important nutritional mechanisms responsible for the difference in response of different genotypic oilseed rapes to boron deficiency. PMID:11757364

Lou, Y; Yang, Y

2001-04-01

215

NASA's Advanced Radioisotope Power Conversion Technology Development Status  

NASA Technical Reports Server (NTRS)

NASA's Advanced Radioisotope Power Systems (ARPS) project is developing the next generation of radioisotope power conversion technologies that will enable future missions that have requirements that cannot be met by either photovoltaic systems or by current radioisotope power systems (RPSs). Requirements of advanced RPSs include high efficiency and high specific power (watts/kilogram) in order to meet future mission requirements with less radioisotope fuel and lower mass so that these systems can meet requirements for a variety of future space applications, including continual operation surface missions, outer-planetary missions, and solar probe. These advances would enable a factor of 2 to 4 decrease in the amount of fuel required to generate electrical power. Advanced RPS development goals also include long-life, reliability, and scalability. This paper provides an update on the contractual efforts under the Radioisotope Power Conversion Technology (RPCT) NASA Research Announcement (NRA) for research and development of Stirling, thermoelectric, and thermophotovoltaic power conversion technologies. The paper summarizes the current RPCT NRA efforts with a brief description of the effort, a status and/or summary of the contractor's key accomplishments, a discussion of upcoming plans, and a discussion of relevant system-level benefits and implications. The paper also provides a general discussion of the benefits from the development of these advanced power conversion technologies and the eventual payoffs to future missions (discussing system benefits due to overall improvements in efficiency, specific power, etc.).

Anderson, David J.; Sankovic, John; Wilt, David; Abelson, Robert D.; Fleurial, Jean-Pierre

2007-01-01

216

NASA Radioisotope Power System Program - Technology and Flight Systems  

NASA Technical Reports Server (NTRS)

NASA sometimes conducts robotic science missions to solar system destinations for which the most appropriate power source is derived from thermal-to-electrical energy conversion of nuclear decay of radioactive isotopes. Typically the use of a radioisotope power system (RPS) has been limited to medium and large-scale missions, with 26 U,S, missions having used radioisotope power since 1961. A research portfolio of ten selected technologies selected in 2003 has progressed to a point of maturity, such that one particular technology may he considered for future mission use: the Advanced Stirling Converter. The Advanced Stirling Radioisotope Generator is a new power system in development based on this Stirling cycle dynamic power conversion technology. This system may be made available for smaller, Discovery-class NASA science missions. To assess possible uses of this new capability, NASA solicited and funded nine study teams to investigate unique opportunities for exploration of potential destinations for small Discovery-class missions. The influence of the results of these studies and the ongoing development of the Advanced Stirling Radioisotope Generator system are discussed in the context of an integrated Radioisotope Power System program. Discussion of other and future technology investments and program opportunities are provided.

Sutliff, Thomas J.; Dudzinski, Leonard A.

2009-01-01

217

Thermionic properties of the molybdenum boron system  

SciTech Connect

The thermionic work function has been measured as a function of composition within the various two phase regions between Mo and MoB/sub 2/. Values at the low boron and high boron phase boundaries for the various compounds were obtained by extrapolation. The following effective work functions were obtained: Mo/sub 2/B (low boron) = 3.08 eV; Mo/sub 2/B (high boron) = 3.63 eV; ..cap alpha..-MoB (low boron) = 3.38 eV; ..cap alpha..-MoB (high boron) = 4.30 eV; ..beta..-MoB (low boron) = 2.83 eV; ..beta..-MoB (high boron) = 3.92; Mo/sub 2/B/sub 3/ (low boron) = 4.65 eV; Mo/sub 2/B/sub 3/ (high boron) = 3.85 eV; and MoB/sub 2/ (low boron) = 3.52 eV. Because the composition range of these compounds is very narrow, the work function is very sensitive to the composition within the single phase regions.

Storms, E.K.

1980-01-01

218

High-Power Target System for Radioisotope Production.  

National Technical Information Service (NTIS)

To utilize the powerful external beams, available from H sup - cyclotrons, a high-power, target system was designed by The Cyclotron Corp. of Berkeley, CA and further developed at TRIUMF. The system consists of two target stations served by beam lines fro...

J. J. Burgerjon, Z. Gelbart, G. O. Hendry, J. C. Lofvendahl, L. McIlwraith

1986-01-01

219

Radioisotope production facility for use with positron emission tomography  

SciTech Connect

This patent describes a system for producing radionuclides for use with positron emission tomography (PET). It comprises a source of ions for producing a {sup 3}He++ beam at a low energy; radio frequency quadrupole (RFQ) accelerator means for accelerating the {sup 3}He{sup ++} beam to an energy level of about 8 MeV; and a target system having a selected target compound therein irradiated with the accelerated {sup 3}He{sup ++} beam to produce at least one radionuclide having application to PET.

Dabiri, A.E.; Hagan, W.K.

1991-08-06

220

Regioselective alkylation of heteroaromatic compounds with 3-methyl-2-quinonyl boronic acids.  

PubMed

Reactions of heteroaromatic compounds with 3-methyl substituted 2-quinonyl boronic acids proceeded by 1,4-addition followed by spontaneous protodeboronation, leading directly to the Friedel-Crafts alkylation products instead of the commonly observed alkenylation derivatives resulting from quinones. The boronic acid acts as a temporary regiocontroller, making the system a highly reactive quinone equivalent and opening a direct access to 5,5-disubstituted cyclohexene-1,4-diones. PMID:21218792

Veguillas, Marcos; Ribagorda, María; Carreño, M Carmen

2011-02-18

221

Boron translocation in coffee trees  

Microsoft Academic Search

Boron deficiency in coffee trees (Coffea arabica) is widespread, however, responses to B fertilizer have been erratic, depending on the year, method, and time of application. A better understanding of B uptake, distribution, and remobilization within the plant is important in developing a rational fertilization program. Field\\u000a and greenhouse experiments were conducted to study B distribution and remobilization in coffee

Vagner M. Leite; Patrick H. Brown; Ciro A. Rosolem

2007-01-01

222

Primary system boron dilution analysis  

Microsoft Academic Search

The results are presented for an analysis conducted to determine the potential paths through which nonborated water or water with insufficient boron concentration might enter the LOFT primary coolant piping system or reactor vessel to cause dilution of the borated primary coolant water. No attempt was made in the course of this analysis to identify possible design modifications nor to

R. J. Crump; C. J. Naretto; R. A. Borgen; H. C. Rockhold

1978-01-01

223

The performance of a boron-loaded gel-fuel ramjet  

NASA Astrophysics Data System (ADS)

The present work focuses on the possibility of combining the advantages of ramjet propulsion with the high energetic potential of boron. However, the use of boron poses two major challenges. The first, common to all solid additives to liquid fuels is particle sedimentation and poor dispersion. This problem is solved through the use of a gel fuel. The second obstacle, specific to boron-enriched fuels, is the difficulty in realizing the full energetic potential of boron. This could be overcome by means of an aft-combustion chamber, where fuel-rich combustion products are mixed with cold bypass air. Cooling causes the gaseous boron oxide to condense and, as a consequence, the heat of evaporation trapped in the gaseous oxide is released. The merits of such a combination are assessed through its ability to power an air-to-surface missile of relatively small size, capable of delivering a large payload to over a distance of about 1000 km in short time. The paper presents a preliminary design of a ramjet missile using a gel fuel loaded with boron. The thermochemical aspects of the two-stage combustion of the fuel are considered. A comparison with a solid rocket motor (SRM) missile launched under the same conditions as the ramjet missile is made. The boron-loaded gel-fuel ramjet is found superior for this mission.

Haddad, A.; Natan, B.; Arieli, R.

2011-10-01

224

High Efficiency Thermoelectric Radioisotope Power Systems  

NASA Technical Reports Server (NTRS)

The work performed and whose results presented in this report is a joint effort between the University of New Mexico s Institute for Space and Nuclear Power Studies (ISNPS) and the Jet Propulsion Laboratory (JPL), California Institute of Technology. In addition to the development, design, and fabrication of skutterudites and skutterudites-based segmented unicouples this effort included conducting performance tests of these unicouples for hundreds of hours to verify theoretical predictions of the conversion efficiency. The performance predictions of these unicouples are obtained using 1-D and 3-D models developed for that purpose and for estimating the actual performance and side heat losses in the tests conducted at ISNPS. In addition to the performance tests, the development of the 1-D and 3-D models and the development of Advanced Radioisotope Power systems for Beginning-Of-Life (BOM) power of 108 We are carried out at ISNPS. The materials synthesis and fabrication of the unicouples are carried out at JPL. The research conducted at ISNPS is documented in chapters 2-5 and that conducted at JP, in documented in chapter 5. An important consideration in the design and optimization of segmented thermoelectric unicouples (STUs) is determining the relative lengths, cross-section areas, and the interfacial temperatures of the segments of the different materials in the n- and p-legs. These variables are determined using a genetic algorithm (GA) in conjunction with one-dimensional analytical model of STUs that is developed in chapter 2. Results indicated that when optimized for maximum conversion efficiency, the interfacial temperatures between various segments in a STU are close to those at the intersections of the Figure-Of-Merit (FOM), ZT, curves of the thermoelectric materials of the adjacent segments. When optimizing the STUs for maximum electrical power density, however, the interfacial temperatures are different from those at the intersections of the ZT curves, but close to those at the intersections the characteristic power, CP, curves of the thermoelectric materials of the adjacent segments (CP = T(sup 2)Zk and has a unit of W/m). Results also showed that the number of the segments in the n- and p-legs of the STUs optimized for maximum power density are generally fewer than when the same unicouples are optimized for maximum efficiency. These results are obtained using the 1-D optimization model of STUs that is detailed in chapter 2. A three-dimensional model of STUs is developed and incorporated into the ANSYS commercial software (chapter 3). The governing equations are solved, subject to the prescribed

El-Genk, Mohamed; Saber, Hamed; Caillat, Thierry

2004-01-01

225

The shocking development of lithium (and boron) in supernovae  

NASA Technical Reports Server (NTRS)

It is shown that significant amounts of Li-7 and B-11 are produced in Type 2 supernovae. The synthesis of these rare elements occurs as the supernova shock traverses the base of the hydrogen envelope burning He-3 to masses 7 and 11 via alpha capture. The yields in this process are sufficient to account for the difference in lithium abundance observed between Pop 2 and Pop 1 stars. Since lithium (and boron) would, in this manner, be created in the same stars that produce the bulk of the heavy elements, the lithium abundance even in old Pop 1 stars would be high (as observed). The B-11 production may remedy the long-standing problem of the traditional spallation scenario to account for the observed isotopic ratio of boron. Observational consequences of this mechanism are discussed, including the evolution of lithium and boron isotope ratios in the Galaxy and the possible use of the boron yields to constrain the number of blue progenitor Type 2 supernovae.

Dearborn, David S. P.; Schramm, David N.; Steigman, Gary; Truran, James

1989-01-01

226

Intraoperative Subareolar Radioisotope Injection for Immediate Sentinel Lymph Node Biopsy  

PubMed Central

Objective: To determine the identification of sentinel lymph node biopsy (SLNB) in breast cancer patients after intraoperative injection of unfiltered technetium-99m sulfur colloid (Tc-99) and blue dye. Background: SLNB guided by a combination of radioisotope and blue dye injection yields the best identification rates in breast cancer patients. Radioisotope is given preoperatively, without local anesthesia, whereas blue dye is given intraoperatively. We hypothesized that, because of the rapid drainage noted with the subareolar injection technique of radioisotope, intraoperative injection would be feasible and less painful for SLN localization in breast cancer patients. Methods: Intraoperative injection of Tc-99 and confirmation blue dye was performed using the subareolar technique for SLNB in patients with operable breast cancer. The time lapse between injection and axillary incision, the background count, the preincision and ex vivo counts of the hot nodes, and the axillary bed counts were documented. The identification rate was recorded. Results: Ninety-six SLNB procedures were done in 88 patients with breast cancer employing intraoperative subareolar injection technique for both radioisotope (all 96 procedures) and blue dye (93 procedures) injections. Ninety-three (97%) procedures had successful identification; all SLNs were hot; 91 (of 93 procedures with blue dye) were blue and hot. The mean time from radioisotope injection to incision was 19.9 minutes (SD 8.5 minutes). The mean highest 10 second count was 88,544 (SD 55,954). Three of 96 (3%) patients with failure of localization had previous excisional biopsies: 1 circumareolar and 2 upper outer quadrant incisions that may have disrupted the lymphatic flow. Conclusion: Intraoperative subareolar injection of radioisotope rapidly drains to the SLNs and allows immediate staging of the axilla, avoiding the need to coordinate diagnostic services and a painful preoperative procedure. PMID:15166963

Layeeque, Rakhshanda; Kepple, Julie; Henry-Tillman, Ronda S.; Adkins, Laura; Kass, Rena; Colvert, Maureen; Gibson, Regina; Mancino, Anne; Korourian, Soheila; Klimberg, V Suzanne

2004-01-01

227

Determination of dispersion coefficients using radioisotope data in river environment.  

PubMed

A field tracer experiment using radioisotope (82)Br was performed to estimate the dispersion characteristics of pollutants in river environment. The dispersion coefficients in the longitudinal and transverse directions were determined by using the measured concentration of a radioisotope. Numerical models were applied to calculate the flow and concentration fields at the experimental site. Several numerical simulations were performed to investigate the effects of the numerical results according to variations of the dispersion coefficients. The calculated results for several runs were compared with the measured ones by using statistical methods. The calculated concentrations agreed well with the measured ones. PMID:19303788

Suh, K S; Kim, K C; Jung, S H; Lee, J Y

2009-01-01

228

Small Radioisotope Power System at NASA Glenn Research Center  

NASA Technical Reports Server (NTRS)

In April 2009, NASA Glenn Research Center (GRC) formed an integrated product team (IPT) to develop a Small Radioisotope Power System (SRPS) utilizing a single Advanced Stirling Convertor (ASC) with passive balancer for possible use by the International Lunar Network (ILN) program. The ILN program is studying the feasibility of implementing a multiple node seismometer network to investigate the internal lunar structure. A single ASC produces approximately 80 W(sub e) and could potentially supply sufficient power for that application. The IPT consists of Sunpower, Inc., to provide the single ASC with balancer, The Johns Hopkins University Applied Physics Laboratory (JHU/APL) to design an engineering model Single Convertor Controller (SCC) for an ASC with balancer, and NASA GRC to provide technical support to these tasks and to develop a simulated lunar lander test stand. A controller maintains stable operation of an ASC. It regulates the alternating current produced by the linear alternator of the convertor, provides a specified output voltage, and maintains operation at a steady piston amplitude and hot end temperature. JHU/APL also designed an ASC dynamic engine/alternator simulator to aid in the testing and troubleshooting of the SCC. This paper describes the requirements, design, and development of the SCC, including some of the key challenges and the solutions chosen to overcome those issues. In addition, it describes the plans to analyze the effectiveness of a passive balancer to minimize vibration from the ASC, characterize the effect of ASC vibration on a lunar lander, characterize the performance of the SCC, and integrate the single ASC, SCC, and lunar lander test stand to characterize performance of the overall system.

Dugala, Gina M.; Fraeman, Martin; Frankford, David P.; Duven, Dennis; Shamkovich, Andrei; Ambrose, Hollis; Meer, David W.

2012-01-01

229

Small Radioisotope Power System Testing at NASA Glenn Research Center  

NASA Technical Reports Server (NTRS)

In April 2009, NASA Glenn Research Center (GRC) formed an integrated product team (IPT) to develop a Small Radioisotope Power System (SRPS) utilizing a single Advanced Stirling Convertor (ASC) with passive balancer. A single ASC produces approximately 80 We making this system advantageous for small distributed lunar science stations. The IPT consists of Sunpower, Inc., to provide the single ASC with a passive balancer, The Johns Hopkins University Applied Physics Laboratory (JHUAPL) to design an engineering model Single Convertor Controller (SCC) for an ASC with a passive balancer, and NASA GRC to provide technical support to these tasks and to develop a simulated lunar lander test stand. The single ASC with a passive balancer, simulated lunar lander test stand, and SCC were delivered to GRC and were tested as a system. The testing sequence at GRC included SCC fault tolerance, integration, electromagnetic interference (EMI), vibration, and extended operation testing. The SCC fault tolerance test characterized the SCCs ability to handle various fault conditions, including high or low bus power consumption, total open load or short circuit, and replacing a failed SCC card while the backup maintains control of the ASC. The integrated test characterized the behavior of the system across a range of operating conditions, including variations in cold-end temperature and piston amplitude, including the emitted vibration to both the sensors on the lunar lander and the lunar surface. The EMI test characterized the AC and DC magnetic and electric fields emitted by the SCC and single ASC. The vibration test confirms the SCCs ability to control the single ASC during launch. The extended operation test allows data to be collected over a period of thousands of hours to obtain long term performance data of the ASC with a passive balancer and the SCC. This paper will discuss the results of each of these tests.

Dugala, Gina; Bell, Mark; Oriti, Salvatore; Fraeman, Martin; Frankford, David; Duven, Dennis

2013-01-01

230

Concept for a radioisotope powered dual mode lunar rover  

NASA Technical Reports Server (NTRS)

Over three decades ago, the Apollo missions manifestly demonstrated the value of a lunar rover to expand the exploration activities of lunar astronauts. The stated plan of the new Vision for Space Exploration to establish a permanent presence on the moon in the next decades gives new impetus to providing long range roving and exploration capability in support of the siting, construction, and maintenance of future human bases. The incorporation of radioisotope power systems and telerobotic capability in the design has the potential to significantly expand the capability of such a rover, allowing continuous operation during the full lunar day/night cycle, as well as enabling exploration in permanently shadowed regions that may be of interest to humans for the resources they may hold. This paper describes a concept that builds on earlier studies originated in the Apollo program for a Dual Mode (crewed and telerobotic) Lunar Roving Vehicle (DMLRV). The goal of this vehicle would be to provide a multipurpose infrastructure element and remote science platform for the exploration of the moon. The DMLRV would be essential for extending the productivity of human exploration crews, and would provide a unique capability for diverse long-range, long-duration science exploration between human visits. With minimal reconfiguration this vehicle could also provide the basic platform to support a range of site survey and preparation activities in anticipation of the establishment of a permanent human presence on the moon. A conceptual design is presented for the DMLRV, including discussion of mission architecture, vehicle performance, representative science payload accommodation, and equipment and crew radiation considerations.

Elliott, John O.; Schriener, Timothy M.; Coste, Keith

2006-01-01

231

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

Microsoft Academic Search

Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy.

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

2008-01-01

232

Ferromagnetism and semiconducting of boron nanowires  

PubMed Central

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 ?-rhombohedral boron (?-B) and ?-rhombohedral boron (?-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 ?-B-based or the ?-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 ?B, respectively, for the ?-c [001] and ?-c [001] directions. Electronically, when the boron nanowire grows along the ?-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

2012-01-01

233

Ferromagnetism and semiconducting of boron nanowires  

NASA Astrophysics Data System (ADS)

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 ?-rhombohedral boron (?-B) and ?-rhombohedral boron (?-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 ?-B-based or the ?-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 ?B, respectively, for the ?-c [001] and ?-c [001] directions. Electronically, when the boron nanowire grows along the ?-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.

Li, Jiling L.; He, Tao; Yang, Guowei

2012-12-01

234

Ferromagnetism and semiconducting of boron nanowires.  

PubMed

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 ?-rhombohedral boron (?-B) and ?-rhombohedral boron (?-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 ?-B-based or the ?-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 ?B, respectively, for the ?-c [001] and ?-c [001] directions. Electronically, when the boron nanowire grows along the ?-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

Li, Jiling L; He, Tao; Yang, Guowei

2012-01-01

235

A study of palladium thin-films for radioisotope storage in betavoltaic power sources designs  

Microsoft Academic Search

A betavoltaic cell is a type of radioisotope power source where the energy of beta radiation is converted into electricity. The goal of the research is to design a novel thin-film material to store radioisotopes that exhibits consistent and optimal radiation emission efficiencies. To achieve the main goal, three tasks were performed: review the radioisotope power technology, evaluate the methods

Thomas E Adams

2011-01-01

236

Radiobiological evaluation of new boron delivery agents for boron neutron capture therapy  

E-print Network

This thesis evaluates the radiobiological effectiveness of three new boron compounds namely a boronated porphyrin (BOPP) and two liposome formulations for neutron capture therapy (BNCT). The methodology utilizes in vitro ...

Chung, Yoonsun

2008-01-01

237

Enhancement of electrical conductivity and electrochemical activity of hydrogenated amorphous carbon by incorporating boron atoms  

NASA Astrophysics Data System (ADS)

Conductive boron-doped hydrogenated amorphous carbon (B-DLC) thin films were successfully synthesized with RF plasma-enhanced CVD method. By incorporating boron atoms in amorphous carbon, conduction types were changed from n- to p-type, and volume resistivity was decreased from 30.4 (non-doped) to 6.36 × 10-2 ? cm (B/C = 2.500 atom%). B-DLC film with sp2/(sp2 + sp3) carbons of 75 atom% exhibited high resistance to electrochemically-induced corrosion in strong acid solution. Furthermore, it was clarified that boron atoms in DLC could enhance kinetics of hydrogen evolution during water electrolysis at B-DLC surface. B-DLC is, therefore, a promising electrode material for hydrogen production by increasing the concentration of boron atoms in B-DLC and enhancing the reactivity of H2 evolution.

Naragino, Hiroshi; Yoshinaga, Kohsuke; Nakahara, Akira; Tanaka, Sakuya; Honda, Kensuke

2013-06-01

238

Modeling of boron species in the Falcon 17 and ISP-34 integral tests  

SciTech Connect

The RAFT computer code for aerosol formation and transport was modified to include boron species in its chemical database. The modification was necessary to calculate fission product transport and deposition in the FAL-17 and ISP-34 Falcon tests, where boric acid was injected. The experimental results suggest that the transport of cesium is modified in the presence of boron. The results obtained with the modified RAFT code are presented; they show good agreement with experimental results for cesium and partial agreement for boron deposition in the Falcon silica tube. The new version of the RAFT code predicts the same behavior for iodine deposition as the previous version, where boron species were not included.

Lazaridis, M.; Capitao, J.A.; Drossinos, Y. [Commission of the European Communities, Ispra (Italy). Joint Research Centre

1996-09-01

239

Synthesis of boron-substituted diaryliodonium salts and selective transformation into functionalized aryl boronates.  

PubMed

Dormant boron awaits its true destiny in diaryliodonium salts synthesized from aryl boronate derivatives according to two alternative general methods with hypervalent iodine(III) reagents and fluoroalcohol solvents: transformation of an aryl C-H bond and boron-iodine(III) exchange (see scheme; FG = functional group). The salts could be functionalized by both catalyst-free and metal-catalyzed reactions without loss of the boron functionality. PMID:23139190

Ito, Motoki; Itani, Itsuki; Toyoda, Yosuke; Morimoto, Koji; Dohi, Toshifumi; Kita, Yasuyuki

2012-12-01

240

Aromaticity of planar boron clusters confirmed.  

PubMed

Low-energy boron clusters are characterized by two-dimensional geometry. Aromaticity of these planar boron clusters was established in terms of topological resonance energy (TRE). All planar boron clusters were found to be highly aromatic with large positive TREs even if they have 4n pi-electrons. Aromaticity must therefore be the origin of unusual planar or quasi-planar geometry. Thus, the aromaticity concept is as useful in boron chemistry as it is in general organic chemistry. It is evident that the Hückel 4n + 2 rule of aromaticity should not be applied to such polycyclic pi-systems. Some of the boron clusters are in the triplet electronic state to attain higher aromaticity. Multivalency and electron deficiency of boron atoms are responsible for lowering the energies of low-lying pi molecular orbitals and then for enhancing aromaticity. For polycyclic pi-systems, paratropicity does not always indicate antiaromaticity. PMID:16173765

Aihara, Jun-ichi; Kanno, Hideaki; Ishida, Toshimasa

2005-09-28

241

Molecular basis of adaptation to high soil boron in wheat landraces and elite cultivars.  

PubMed

Environmental constraints severely restrict crop yields in most production environments, and expanding the use of variation will underpin future progress in breeding. In semi-arid environments boron toxicity constrains productivity, and genetic improvement is the only effective strategy for addressing the problem. Wheat breeders have sought and used available genetic diversity from landraces to maintain yield in these environments; however, the identity of the genes at the major tolerance loci was unknown. Here we describe the identification of near-identical, root-specific boron transporter genes underlying the two major-effect quantitative trait loci for boron tolerance in wheat, Bo1 and Bo4 (ref. 2). We show that tolerance to a high concentration of boron is associated with multiple genomic changes including tetraploid introgression, dispersed gene duplication, and variation in gene structure and transcript level. An allelic series was identified from a panel of bread and durum wheat cultivars and landraces originating from diverse agronomic zones. Our results demonstrate that, during selection, breeders have matched functionally different boron tolerance alleles to specific environments. The characterization of boron tolerance in wheat illustrates the power of the new wheat genomic resources to define key adaptive processes that have underpinned crop improvement. PMID:25043042

Pallotta, Margaret; Schnurbusch, Thorsten; Hayes, Julie; Hay, Alison; Baumann, Ute; Paull, Jeff; Langridge, Peter; Sutton, Tim

2014-10-01

242

Monte Carlo Radiation Analysis of a Spacecraft Radioisotope Power System  

NASA Technical Reports Server (NTRS)

A Monte Carlo statistical computer analysis was used to create neutron and photon radiation predictions for the General Purpose Heat Source Radioisotope Thermoelectric Generator (GPHS RTG). The GPHS RTG is being used on several NASA planetary missions. Analytical results were validated using measured health physics data.

Wallace, M.

1994-01-01

243

Integrated bandpass filter contacts for radioisotope thermophotovoltaic cells  

Microsoft Academic Search

Smaller spacecraft deployed on deep space missions will require improved electrical power generation efficiency above that which is presently available from radioisotope powered thermoelectric devices. Low bandgap thermophotovoltaic (TPV) devices, when used in conjunction with spectrally modified or filtered emitters, offer the promise of 4 to 5 times efficiency improvement. Integrating spectral filters into PV cell contacts can further improve

William E. Horne; Mark D. Morgan; Vasan S. Sundaram

1996-01-01

244

Design Characteristics of a Cyclotron for Producing Radioisotopes.  

National Technical Information Service (NTIS)

A description is given of the construction and parts design of a cyclotron for producing radioisotopes in automated target devices and for accelerating protons to an energy of 25 MeV. 8 references, 8 figures, 2 tables. (ERA citation 08:012827)

N. V. Akulova, P. V. Bogdanov, I. F. Malyshev, V. Y. Moiseev, V. N. Moshkin

1981-01-01

245

Boron Removal by Polymer-Assisted Ultrafiltration  

Microsoft Academic Search

Boron contamination of natural waters is a widespread environmental problem which lacks a cost-effective solution. Polymer-assisted ultrafiltration is a method of boron removal that is compatible with other water-treatment processes. This boron removal technique exploits the pH-dependent complexation between boric acid and a macromolecule containing vicinal diol groups to prevent boric acid from passing through an ultrafiltration membrane. The concentration

Bryan M. Smith; Paul Todd; Christopher N. Bowman

1995-01-01

246

Boron removal in brackish water desalination systems  

Microsoft Academic Search

Boron removal in seawater RO desalination systems is usually done by a second desalination pass, operating at high pH (pH?10). This method is not economical for reduction of boron content in permeate of brackish water desalination. The most suitable method for this purpose would be through boron selective ion exchange (IX) resins. However, in some cases the use of high

P. Glueckstern; M. Priel

2007-01-01

247

Synthesis of functionalized cyclic boronates.  

PubMed

Deprotonation of a simple borylated allylic sulfone and subsequent alkylation with certain unsaturated electrophiles provide substrates that are easily converted into functionalized alkenyl boronates with ring sizes from five- to seven-membered. A Chan-Lam reaction on one such substrate afforded an alkoxyallylic sulfone that was readily converted via a (4 + 3)-cycloaddition to a polycycle possessing the ABC ring substructure of ingenol. PMID:24308760

Altenhofer, Erich; Harmata, Michael

2014-01-01

248

Boron mullite: Formation and basic characterization  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Decrease of B-mullite formation temperature with increasing boron content. ? Decrease of lattice parameters b and c with increasing boron content. ? Significant reduction of thermal expansion (?15%) due to incorporation of boron. ? Decomposition of B-mullite at 1400 °C, long-term stability at 800 °C. -- Abstract: A series of boron doped mullites (B-mullite) was prepared from single-phase gels with initial compositions based on a 1:1 isomorphous substitution of Si by B, starting from a 3:2 mullite composition (Al{sub 4.5}Si{sub 1.5}O{sub 9.75}). A high amount of boron (>10 mol.%) can be incorporated into the crystal structure of mullite where it most likely replaces Si. In situ phase formation of B-mullites was studied with high temperature X-ray diffraction and thermal analysis. A decrease of the formation temperature for B-mullite with increasing boron content was observed. With increasing boron content lattice parameters b and c significantly decrease, while no systematic evolution of a is observed. Long annealing at 1400 °C results in decomposition of B-mullite to boron free mullite and ?-alumina. At 800 °C B-mullite appears to be stable over a period of at least 12 days. The mean thermal expansion coefficient was reduced by 15% upon incorporation of boron which makes the material technologically interesting.

Lührs, Hanna, E-mail: hanna.luehrs@uni-bremen.de [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany)] [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany); Fischer, Reinhard X. [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany)] [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany); Schneider, Hartmut [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany) [Universität Bremen, FB 5 Geowissenschaften, Klagenfurter Straße, D-28359 Bremen (Germany); Universität Köln, Institut für Kristallographie, Greinstraße 6, D-50939 Kölm (Germany)

2012-12-15

249

The Abundance of Interstellar Boron  

E-print Network

We use new Space Telescope Imaging Spectrograph (STIS) and archival Goddard High Resolution Spectrograph (GHRS) observations to study interstellar B II 1362 and O I 1355 absorption along seven sightlines. Our new column density measurements, combined with measurements of four sightlines from the literature, allow us to study the relative B/O abundances over a wide range of interstellar environments. We measure sightline-integrated relative gas-phase abundances in the range [B/O] = -1.00 to -0.17, and our data show the B/O abundances are anticorrelated with average sightline densities over the range log ~ -1.3 to +0.7. Detailed comparisons of the B II and O I line shapes show that the B/O ratio is significantly higher in warm interstellar clouds than in cool clouds. These results are consistent with the incorporation of boron into dust grains in the diffuse ISM. Since boron is likely incorporated into grains, we derive a lower limit to the present-day total (gas+dust) interstellar boron abundance of B/H > (2.5+/-0.9)x10^-10. The effects of dust depletion and ionization differences from element to element will make it very difficult to reliably determine 11B/10B along most interstellar sightlines.

J. Christopher Howk; Kenneth R. Sembach; Blair D. Savage

2000-05-25

250

The Boron Efflux Transporter ROTTEN EAR Is Required for Maize Inflorescence Development and Fertility[C][W][OPEN  

PubMed Central

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

Chatterjee, Mithu; Tabi, Zara; Galli, Mary; Malcomber, Simon; Buck, Amy; Muszynski, Michael; Gallavotti, Andrea

2014-01-01

251

Boron in siliceous materials as a paleosalinity indicator *  

NASA Astrophysics Data System (ADS)

The 10B(n, ?) 7Li nuclear reaction has been used with alpha-sensitive plastic track detectors to determine boron concentrations in siliceous live-collected and fossil sponge spicules. This radiographic technique allows B determinations with 5-6% uncertainties on objects 20-25 ?m in diameter and for concentrations as low as 0.5 ppm. Boron concentrations in spicules from different specimens from the same location agreed to within 10% when the spicules were not: (1) smaller than 20 ?m in diameter, (2) from dictyonine skeletons, (3) the extremely large root-like spicules found in some soft substrate hexactinellids, or (4) microscleres. These criteria also applied to spicules found in sediment samples. Spicules from live-collected sponges exhibited a taxonomy-independent correlation of B concentrations with water salinity for samples from regions of low water temperature and high productivity. Measured concentrations ranged from nearly 0 ppm B (freshwater sponges) to 500-700 ppm (marine sponges), with intermediate values for brackish-water specimens. However, spicules from tropical, low-productivity marine locations contained markedly less boron than spicules from temperate, high-productivity regions. Thus, water temperature and/or food supply also seem to influence B concentrations. Pleistocene spicules from deep-sea cores contained less boron than was expected in comparison with live-collected spicules based on present water temperatures and nutrient supplies, but B concentrations did not vary with depth in the cores. Infrared spectroscopy, electron microprobe analysis and visual inspection revealed no evidence for chemical or mineralogic alteration. It is not clear whether the lower B concentrations of the Pleistocene samples are the result of diagenetic processes or the as yet undefined effects of differences in food supply and/or environmental conditions.

Furst, Marian J.

1981-01-01

252

Potential Applications for Radioisotope Power Systems in Support of Human Exploration Missions  

NASA Technical Reports Server (NTRS)

Radioisotope power systems (RPS) for space applications have powered over 27 U.S. space systems, starting with Transit 4A and 4B in 1961, and more recently with the successful landing of the Mars Science Laboratory rover Curiosity in August 2012. RPS enable missions with destinations far from the Sun with faint solar flux, on planetary surfaces with dense or dusty atmospheres, and at places with long eclipse periods where solar array sizes and energy storage mass become impractical. RPS could also provide an enabling capability in support of human exploration activities. It is envisioned that with the higher power needs of most human mission concepts, a high efficiency thermal-to-electric technology would be required such as the Advanced Stirling Radioisotope generator (ASRG). The ASRG should be capable of a four-fold improvement in efficiency over traditional thermoelectric RPS. While it may be impractical to use RPS as a main power source, many other applications could be considered, such as crewed pressurized rovers, in-situ resource production of propellants, back-up habitat power, drilling, any mobile or remote activity from the main base habitat, etc. This paper will identify potential applications and provide concepts that could be a practical extension of the current ASRG design in providing for robust and flexible use of RPS on human exploration missions.

Cataldo, Robert L.; Colozza, Anthony J.; Schmitz, Paul C.

2013-01-01

253

Porphyrins for boron neutron capture therapy  

DOEpatents

Novel compounds for treatment of brain tumors in Boron Neutron Capture Therapy are disclosed. A method for preparing the compounds as well as pharmaceutical compositions containing said compounds are also disclosed. The compounds are water soluble, non-toxic and non-labile boronated porphyrins which show significant uptake and retention in tumors.

Miura, Michiko (Center Moriches, NY); Gabel, Detlef (Bremen, DE)

1990-01-01

254

Boron Combustion Characteristics in Ducted Rockets  

Microsoft Academic Search

A test program was performed with the objective of experimentally investigating the boron reaction characteristics in a ducted rocket by systematically varying the primary chamber conditions.In order to vary the primary chamber conditions a test device was used which burned boron powder and gaseous propellants (hydrogen or carbon monoxide, oxygen and nitrogen) in the primary motor. The reaction characteristics in

K. SCHADOW

1972-01-01

255

Rare earth-iron-boron-permanent magnets  

Microsoft Academic Search

This patent describes a neodymium-iron-boron permanent magnet containing added rare earth oxide. It is prepared by the method of comprising the steps of: mixing together components: a particulate alloy consisting essentially of neodymium, iron, cobalt, and boron; and a particulate rare earth oxide selected from the group consisting of gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, and mixtures thereof;

Ghandehari

1990-01-01

256

Boron chemicals in diagnosis and therapeutics  

PubMed Central

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

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

257

Metal matrix composite fuel for space radioisotope energy sources  

NASA Astrophysics Data System (ADS)

Radioisotope fuels produce heat that can be used for spacecraft thermal control or converted to electricity. They must retain integrity in the event of destruction or atmospheric entry of the parent spacecraft. Addition of a metal matrix to the actinide oxide could yield a more robust fuel form. Neodymium (III) oxide (Nd2O3) - niobium metal matrix composites were produced using Spark Plasma Sintering; Nd2O3 is a non-radioactive surrogate for americium (III) oxide (Am2O3). Two compositions, 70 and 50 wt% Nd2O3, were mechanically tested under equibiaxial (ring-on-ring) flexure according to ASTM C1499. The addition of the niobium matrix increased the mean flexural strength by a factor of about 2 compared to typical ceramic nuclear fuels, and significantly increased the Weibull modulus to over 20. These improved mechanical properties could result in reduced fuel dispersion in severe accidents and improved safety of space radioisotope power systems.

Williams, H. R.; Ning, H.; Reece, M. J.; Ambrosi, R. M.; Bannister, N. P.; Stephenson, K.

2013-02-01

258

Emitted radiation characteristics of plutonium dioxide radioisotope thermoelectric generators  

NASA Technical Reports Server (NTRS)

The nuclear and emitted radiation characteristics of the radioisotope elements and impurities in commercial grade plutonium dioxide are presented in detail. The development of the methods of analysis are presented. Radioisotope thermoelectric generators (RTG) of 1575, 3468 and 5679 thermal watts are characterized with respect to neutron and gamma photon source strength as well as spatial and number flux distribution. The results are presented as a function of detector position and light element contamination concentration for fuel age ranging from 'fresh' to 18 years. The data may be used to obtain results for given O-18 and Pu-236 concentrations. The neutron and gamma photon flux and dose calculations compare favorably with reported experimental values for SNAP-27.

Gingo, P. J.; Steyn, J. J.

1971-01-01

259

Solid state radioisotopic energy converter for space nuclear power  

SciTech Connect

Recent developments in materials technology now make it possible to fabricate nonthermal thin-film radioisotopic energy converters (REC) with a specific power of 24 W/kg and a 10 year working life at 5 to 10 watts. This creates applications never before possible, such as placing the power supply directly on integrated circuit chips. The efficiency of the REC is about 25% which is two to three times greater than the 6 to 8% capabilities of current thermoelectric systems. Radioisotopic energy converters have the potential to meet many future space power requirements for a wide variety of applications with less mass, better efficiency, and less total area than other power conversion options. These benefits result in significant dollar savings over the projected mission lifetime.

Brown, P.M. (IsoGen Radioisotopic Research Laboratory, 315 S. McLoughlin Blvd., Oregon City, Oregon 97045 (United States))

1993-01-10

260

Environmental assessment for radioisotope heat source fuel processing and fabrication  

SciTech Connect

DOE has prepared an Environmental Assessment (EA) for radioisotope heat source fuel processing and fabrication involving existing facilities at the Savannah River Site (SRS) near Aiken, South Carolina and the Los Alamos National Laboratory (LANL) near Los Alamos, New Mexico. The proposed action is needed to provide Radioisotope Thermoelectric Generators (RTG) to support the National Aeronautics and Space Administration's (NASA) CRAF and Cassini Missions. Based on the analysis in the EA, DOE has determined that the proposed action does not constitute a major Federal action significantly affecting the quality of the human environment within the meaning of the National Environmental Policy Act (NEPA) of 1969. Therefore, an Environmental Impact Statement is not required. 30 refs., 5 figs.

Not Available

1991-07-01

261

Radioisotope Electric Propulsion for Fast Outer Planetary Orbiters  

NASA Technical Reports Server (NTRS)

Recent interest in outer planetary targets by the Office of Space Science has spurred the search for technology options to enable relatively quick missions to outer planetary targets. Several options are being explored including solar electric propelled stages combined with aerocapture at the target and nuclear electric propulsion. Another option uses radioisotope powered electric thrusters to reach the outer planets. Past work looked at using this technology to provide faster flybys. A better use for this technology is for outer planet orbiters. Combined with medium class launch vehicles and a new direct trajectory these small, sub-kilowatt ion thrusters and Stirling radioisotope generators were found to allow missions as fast as 5 to 12 years for objects from Saturn to Pluto, respectively. Key to the development is light spacecraft and science payload technologies.

Oleson, Steven; Benson, Scott; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey

2002-01-01

262

Process for radioisotope recovery and system for implementing same  

DOEpatents

A method of recovering daughter isotopes from a radioisotope mixture. The method comprises providing a radioisotope mixture solution comprising at least one parent isotope. The at least one parent isotope is extracted into an organic phase, which comprises an extractant and a solvent. The organic phase is substantially continuously contacted with an aqueous phase to extract at least one daughter isotope into the aqueous phase. The aqueous phase is separated from the organic phase, such as by using an annular centrifugal contactor. The at least one daughter isotope is purified from the aqueous phase, such as by ion exchange chromatography or extraction chromatography. The at least one daughter isotope may include actinium-225, radium-225, bismuth-213, or mixtures thereof. A liquid-liquid extraction system for recovering at least one daughter isotope from a source material is also disclosed.

Meikrantz, David H. (Idaho Falls, ID); Todd, Terry A. (Aberdeen, ID); Tranter, Troy J. (Idaho Falls, ID); Horwitz, E. Philip (Naperville, IL)

2009-10-06

263

The polarographic microdetermination of boron  

E-print Network

. Furthermore, the techniques in these methods are long and tedious, and extensive alcoholic distillation introduces errors of undeterminable magnitude. The titration of boric acid using mannitol, as in Chapin's method, is based upon a reaction between boric...? plexes in which there is a tetrahedral boron atom are acidic. This is true in all of such di-diol complexes, as There seems to be little doubt that the enhancement of the acidic properties of boric acid is due to the di-diol complex (82). Mellon...

Peacock, Dixon Williams

2013-10-04

264

Boron Enrichment in Martian Clay  

PubMed Central

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

Nagashima, Kazuhide; Freeland, Stephen J.

2013-01-01

265

Boron enrichment in martian clay.  

PubMed

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

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

2013-01-01

266

Radioisotope Concentration in Lake Sediments of Maracaibo, Venezuela  

SciTech Connect

Maracaibo Lake is one of the most important water basing and oil producing regions in Venezuela. Changes in the local environment have been monitored for chemical pollution in the past. For this study we selected a set of sediment samples collected in the shore and analyzed for its radioisotope content. Results show the gamma emitting isotopes distribution. Isotopes concentrations have been determined within the natural K, Th and U families.

Salas, A. Rangel; Viloria, T. [La Universidad del Zulia (Venezuela); Sajo-Bohus, L.; Barros, H.; Greaves, E. D.; Palacios, D. [Universidad Simon Bolivar (Venezuela)

2007-10-26

267

Isotope Identification in the GammaTracker Handheld Radioisotope Identifier  

SciTech Connect

GammaTracker is a portable handheld radioisotope identifier using position sensitive CdZnTe crystals. The device uses a peak-based method for isotope identification implemented on an embedded computing platform within the device. This paper presents the run-time optimized algorithms used in this peak-based approach. Performance of the algorithms is presented using measured data from gamma-ray sources.

Batdorf, Michael T.; Hensley, Walter K.; Seifert, Carolyn E.; Kirihara, Leslie J.; Erikson, Luke E.; Jordan, David V.

2009-11-13

268

Radioisotope powered alkali metal thermoelectric converter design for space systems  

NASA Technical Reports Server (NTRS)

The design concept of an alkali-metal thermoelectric converter (AMTEC) for 15-30-percent-efficient conversion of heat from the General Purpose (radioisotope) Heat Source (GPHS) on spacecraft is presented. The basic physical principles of the conversion cycle are outlined; a theoretical model is derived; a modular design is described and illustrated with drawings; and the overall AMTEC/GPHS system design is characterized. Predicted performance data are presented in extensive tables and graphs and discussed in detail.

Sievers, R. K.; Bankston, C. P.

1988-01-01

269

Advanced radioisotope power source options for Pluto Express  

SciTech Connect

In the drive to reduce mass and cost, Pluto Express is investigating using an advanced power conversion technology in a small Radioisotope Power Source (RPS) to deliver the required mission power of 74 W(electric) at end of mission. Until this year the baseline power source under consideration has been a Radioisotope Thermoelectric Generator (RTG). This RTG would be a scaled down GPHS RTG with an inventory of 6 General Purpose Heat Sources (GPHS) and a mass of 17.8 kg. High efficiency, advanced technology conversion options are being examined to lower the power source mass and to reduce the amount of radioisotope needed. Three technologies are being considered as the advanced converter technology: the Alkali Metal Thermal-to-Electric Converter (AMTEC), Thermophotovoltaic (TPV) converters, and Stirling Engines. Conceptual designs for each of these options have been prepared. Each converter would require only 2 GPHSs to provide the mission power and would have a mass of 6.1, 7.2, and 12.4 kg for AMTEC, TPV, and Stirling Engines respectively. This paper reviews the status of each technology and the projected performance of an advanced RPS based on each technology. Based on the projected performance and spacecraft integration issues, Pluto Express would prefer to use the AMTEC based RPS. However, in addition to technical performance, selection of a power technology will be based on many other factors.

Underwood, M.L. [California Inst. of Technology, Pasadena, CA (United States). Jet Propulsion Lab.

1995-12-31

270

Hafnium radioisotope recovery from irradiated tantalum  

DOEpatents

Hafnium is recovered from irradiated tantalum by: (a) contacting the irradiated tantalum with at least one acid to obtain a solution of dissolved tantalum; (b) combining an aqueous solution of a calcium compound with the solution of dissolved tantalum to obtain a third combined solution; (c) precipitating hafnium, lanthanide, and insoluble calcium complexes from the third combined solution to obtain a first precipitate; (d) contacting the first precipitate of hafnium, lanthanide and calcium complexes with at least one fluoride ion complexing agent to form a fourth solution; (e) selectively adsorbing lanthanides and calcium from the fourth solution by cationic exchange; (f) separating fluoride ion complexing agent product from hafnium in the fourth solution by adding an aqueous solution of ferric chloride to obtain a second precipitate containing the hafnium and iron; (g) dissolving the second precipitate containing the hafnium and iron in acid to obtain an acid solution of hafnium and iron; (h) selectively adsorbing the iron from the acid solution of hafnium and iron by anionic exchange; (i) drying the ion exchanged hafnium solution to obtain hafnium isotopes. Additionally, if needed to remove residue remaining after the product is dried, dissolution in acid followed by cation exchange, then anion exchange, is performed.

Taylor, Wayne A. (Los Alamos, NM); Jamriska, David J. (Los Alamos, NM)

2001-01-01

271

Boron-Proton Nuclear-Fusion Enhancement Induced in Boron-Doped Silicon Targets by Low-Contrast Pulsed Laser  

NASA Astrophysics Data System (ADS)

We show that a spatially well-defined layer of boron dopants in a hydrogen-enriched silicon target allows the production of a high yield of alpha particles of around 109 per steradian using a nanosecond, low-contrast laser pulse with a nominal intensity of approximately 3×1016 W cm-2. This result can be ascribed to the nature of the long laser-pulse interaction with the target and with the expanding plasma, as well as to the optimal target geometry and composition. The possibility of an impact on future applications such as nuclear fusion without production of neutron-induced radioactivity and compact ion accelerators is anticipated.

Picciotto, A.; Margarone, D.; Velyhan, A.; Bellutti, P.; Krasa, J.; Szydlowsky, A.; Bertuccio, G.; Shi, Y.; Mangione, A.; Prokupek, J.; Malinowska, A.; Krousky, E.; Ullschmied, J.; Laska, L.; Kucharik, M.; Korn, G.

2014-07-01

272

Properties of vacuum-evaporated boron films  

NASA Technical Reports Server (NTRS)

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.

Feakes, F.

1973-01-01

273

Work Began on Contracts for Radioisotope Power Conversion Technology Research and Development  

NASA Technical Reports Server (NTRS)

NASA has had a history of successful space flight missions that depended on radioisotope-fueled power systems. These Radioisotope Power Systems (RPSs) converted the heat generated from the decay of radioisotope material into useful electrical power. An RPS is most attractive in applications where photovoltaics are not optimal, such as deep-space applications where the solar flux is too low or extended applications on planets such as Mars where the day/night cycle, settling of dust, and life requirements limit the usefulness of photovoltaics. NASA s Radioisotope Power Conversion Technology (RPCT) Program is developing next-generation power-conversion technologies that will enable future missions that have requirements that cannot be met by the two RPS flight systems currently being developed by the Department of Energy for NASA: the Multi-Mission Radioisotope Thermoelectric Generator and the Stirling Radioisotope Generator (SRG).

Wong, Wayne A.

2005-01-01

274

PREFACE: The 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008)  

NASA Astrophysics Data System (ADS)

This volume of Journal of Physics: Conference Series contains invited and contributed peer-reviewed papers that were presented at the 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008), which was held on 7-12 September 2008, at Kunibiki Messe, Matsue, Japan. This triennial symposium has a half-century long history starting from the 1st meeting in 1959 at Asbury Park, New Jersey. We were very pleased to organize ISBB 2008, which gathered chemists, physicists, materials scientists as well as diamond and high-pressure researchers. This meeting had a strong background in the boron-related Japanese research history, which includes the discovery of superconductivity in MgB2 and development of Nd-Fe-B hard magnets and of YB66 soft X-ray monochromator. The scope of ISBB 2008 spans both basic and applied interdisciplinary research that is centered on boron, borides and related materials, and the collection of articles defines the state of the art in research on these materials. The topics are centered on: 1. Preparation of new materials (single crystals, thin films, nanostructures, ceramics, etc) under normal or extreme conditions. 2. Crystal structure and chemical bonding (new crystal structures, nonstoichiometry, defects, clusters, quantum-chemical calculations). 3. Physical and chemical properties (band structure, phonon spectra, superconductivity; optical, electrical, magnetic, emissive, mechanical properties; phase diagrams, thermodynamics, catalytic activity, etc) in a wide range of temperatures and pressures. 4. Applications and prospects (thermoelectric converters, composites, ceramics, coatings, etc) There were a few discoveries of new materials, such as nanomaterials, and developments in applications. Many contributions were related to 4f heavy Fermion systems of rare-earth borides. Exotic mechanisms of magnetism and Kondo effects have been discussed, which may indicate another direction of development of boride. Two special sessions, 'Boron chemistry' and 'Superconductivity', were also held at the symposium. The session on Boron chemistry was planned to honor the scientific work in boron chemistry of Professor J Bauer on the occasion of his retirement. Many recent results were discussed in the session, and Professor Bauer himself introduced novel rare-earth-boron-carbon compounds RE10B7C10 (RE = Gd - Er) in his lecture. In the latter session, on the basis of recent discoveries of superconductivity in MgB2 and in ?-boron under high pressure, the superconductivity of boron and related materials was discussed and the superconductivity of boron-doped diamond was also addressed. More than 120 participants from 16 countries attended the ISBB 2008, and active presentations (22 invited, 33 oral and 68 posters) and discussions suggest that research on boron and borides is entering a new phase of development. This volume contains 46 articles from 52 submitted manuscripts. The reviewers were invited not only from symposium participants but also from specialists worldwide, and they did a great job of evaluating and commenting on the submitted manuscripts to maintain the highest quality standard of this volume. Recent discoveries of superconductivity in boron under high pressure, synthesis of a new allotrope of boron and of various boron and boride nanostructures will lead this highly interdisciplinary field of science, which will further grow and gain attention in terms of both basic and applied research. In this context, we are very much looking forward to the next symposium, which will be held in Istanbul, Turkey, in 2011, organized by Professor Onuralp Yucel, Istanbul Technical University. Turkey currently has the world highest share of borate production and is expected to be involved more in boron-related research. Acknowledgements We gratefully acknowledge the style improvement by Dr K Iakoubovskii, and sincerely thank Shimane Prefecture and Matsue City for their financial support. The symposium was also supported by Tokyo University of Science, Suwa and foundations including, the Kajima Foundat

Tanaka, Takaho

2009-07-01

275

Thermodynamic limitation on boron energy realization in ramjet propulsion  

NASA Astrophysics Data System (ADS)

This study addresses a specific boron combustion aspect, revealing that thermodynamic conditions associated with highly boron-loaded ramjet combustors, may lead to blockage of the reaction between boron and air, causing termination of the combustion process, incomplete chemical reaction, and only partial realization of the potential boron combustion energy. Sustained boron combustion may take place when the evaporation rate of the protective liquid boron oxide layer B2O3(l) on the boron particles exceeds its generation rate by the oxidation reaction, typically at temperatures above 1900-2000 K. However, if the actual partial pressure of gaseous boron oxide B2O3(g) produced in the combustion process attains the equilibrium vapor pressure of boron oxide at the conditions existing in the combustion chamber, condensation of the boron oxide to form a liquid layer on the boron particle surfaces may take place, extinguishing the particle combustion by blocking the reaction between the boron and the surrounding oxidizing gas. The study predicts conditions for blockage and incomplete boron combustion over a range of chamber pressures and temperatures. This effect may be characteristic to combustors employing boron-containing fuels, but may not be encountered in the combustion of individual boron particles in air.

Gany, Alon

2014-05-01

276

Design and simulation of MEMS based radioisotope converter with electrostatic capacitive energy conversion mechanism  

Microsoft Academic Search

This paper presents the design and simulation of electrostatic capacitive vibration-to-electricity energy conversion system based on radioisotope Ni 63 that produces low energy beta particles. The electrostatic capacitive energy conversion utilizes a variable capacitor to convert radioisotope energy into electrical energy by mechanical vibration as transformed intermediate. The MEMS capacitor is designed as a radioisotope actuated parallel-plate spring-mass-damping structure fabricated

Haisheng San; Zaijun Cheng; Zhiqiang Deng; Zhiwen Zhao; Yanfei Li; Xuyuan Chen

2011-01-01

277

Relationship Between Plant Availability of Boron and the Physicochemical Properties of Boron in Soils  

Microsoft Academic Search

Boron is an essential micronutrient element required for the normal growth of plants. The range between boron deficiency and\\u000a toxicity symptoms in plants is typically narrow, in the range of 0.028 to 0.093 mmol\\/L for sensitive crops and 0.37 to 1.39\\u000a mmol\\/L for tolerant crops (Goldberg, 1997). Much work has been done on plant availability of boron and physico-chemistry of

Duanwei Zhu; Wang Juan; Shuijiao Liao; Wuding Liu

278

Boron-10 Lined Proportional Counter Wall Effects  

SciTech Connect

The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project 'Coincidence Counting With Boron-Based Alternative Neutron Detection Technology' at Pacific Northwest National Laboratory (PNNL) for development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube based system in the configuration of a coincidence counter. This report provides information about how variations in proportional counter radius and gas pressure in a typical coincident counter design might affect the observed signal from boron-lined tubes. A discussion comparing tubes to parallel plate counters is also included.

Siciliano, Edward R.; Kouzes, Richard T.

2012-05-01

279

Functionalizing graphene by embedded boron clusters.  

PubMed

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 B(7) clusters implanted in a graphene matrix, where the boron clusters are not directly connected. We show that the graphene matrix easily accepts these alternating B(7)-C(6) 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. PMID:21730633

Quandt, Alexander; Ozdo?an, Cem; Kunstmann, Jens; Fehske, Holger

2008-08-20

280

A compendium of the radioisotope thermoelectric generator transportation system and recent programmatic changes  

SciTech Connect

Because RTGs contain significant quantities of radioactive materials, usually plutonium-238 and its decay products, they must be transported in packages built in accordance with 10 CFR 71 (1994). To meet these regulatory requirements, US DOE commissioned Westinghouse Hanford Co. in 1988 to develop a Radioisotope Thermoelectric Generator Transportation System (RTGTS) that would fully comply while protecting RTGs from adverse environmental conditions during normal transport conditions (eg, mainly shock and heat). RTGTS is scheduled for completion Dec. 1996 and will be available to support NASA`s Cassini mission to Saturn in Oct. 1997. This paper provides an overview of the RTGTS project, discusses the hardware being produced, and summarizes various programmatic and management innovations required by recent changes at DOE.

Becker, D.L.; McCoy, J.C.

1996-03-01

281

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

PubMed

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. PMID:23212536

Edward Raja, Chellaiah; Omine, Kiyoshi

2013-08-01

282

Substrate metabolism in isolated rat jejunal epithelium. Analysis using /sup 14/C-radioisotopes  

SciTech Connect

The jejunal epithelium absorbs nutrients from the intestinal lumen and is therefore the initial site for metabolism of these compounds. The purpose of this investigation is to analyze substrate metabolism in a preparation of jejunal epithelium relatively free of other tissues. Novel radioisotopic labelling techniques allow quantitation of substrate metabolism in the TCA cycle, Embden-Meyerhof (glycolytic) pathway, and hexose monophosphate shunt. For example, ratios of /sup 14/CO/sub 2/ production from pairs of /sup 14/C-pyruvate, and /sup 14/C-succinate radioisotopes (CO/sub 2/ ratios) indicate the probability of TCA cycle intermediate efflux to generate compounds other than CO/sub 2/. With (2,3-/sup 14/C)succinate as tracer, the ratio of /sup 14/C in carbon 4 + 5 versus carbon 2 + 3 of citrate, the citrate labelling ratio, equals the probability of TCA intermediate flux to the acetyl CoA-derived portion of citrate versus flux to the oxaloacetate-derived portion. The principal metabolic substrates for the jejunal epithelium are glucose and glutamine. CO/sub 2/ ratios indicate that glutamine uptake and metabolism is partially Na/sup +/-independent, and is saturable, with a half-maximal rate at physiological plasma glutamine concentrations. Glucose metabolism in the jejunal epithelium proceeds almost entirely via the Embden-Meyerhof pathway. Conversion of substrates to multi-carbon products in this tissue allows partial conservation of reduced carbon for further utilization in other tissues. In summary, metabolic modeling based on /sup 14/C labelling ratios is a potentially valuable technique for analysis of metabolic flux patterns in cell preparations.

Mallet, R.T.

1986-01-01

283

Why Boron clusters are Planar?  

NASA Astrophysics Data System (ADS)

The origin of the unusual stability of planar and quasi-planar B12 and B13^+ clusters is explored. Our results demonstrate that in B12 and B13^+ clusters a 6?-6?-delo-6?-3ring trifurcation leads to the triple aromaticity, which is unique to these clusters. Most importantly, the H-L gaps of these clusters are strongly dependent on the strength of the interaction between the inner- and the outer-rings, which make up these clusters. Furthermore, the similarities and the differences between B12 and other stable boron species, B10 and B14 clusters are also discussed. The implication of the current analysis is discussed with respect to Carbon, Silicon and Aluminum clusters.

Boggavarapu, Kiran; Kandalam, Anil

2010-03-01

284

New approach to obtain boron selective emitters  

SciTech Connect

Selective emitters, used in high efficiency solar cells, need a series of oxidations and photolithographic steps that render the process more expensive. In this paper, a new way to make selective emitters using boron is presented. The main feature of this approach is to save oxide growths and photolithographic processes and it is based on the property of boron doped silicon surfaces to be resistant to anisotropic etchings like the one performed during the texturization. Using this characteristic of boron emitter surfaces, the authors can obtain a highly doped emitter under metal grid and simultaneously a shield to avoid texture on these surfaces. First cells were processed and short wavelength response of p{sup +}nn{sup +} solar cells was enhanced by using lightly doped boron emitters in the uncovered area.

Moehlecke, A.; Luque, A. [ETSI Telecomunicacion, Madrid (Spain). Inst. de Energia Solar

1994-12-31

285

Sensitivity of Vertebrate Embryos to Boron Compounds.  

National Technical Information Service (NTIS)

Developmental stages of rainbow trout, channel catfish, goldfish, leopard frog, and Fowler's toad were treated in a continuous flow system with boric acid and borax concentrations ranging from 0.001-300 ppm boron. Exposure was initiated subsequent to fert...

J. A. Black, W. J. Birge

1977-01-01

286

Ni doping of semiconducting boron carbide  

SciTech Connect

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

Hong, Nina; Liu Jing; Adenwalla, S. [Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511 (United States); Langell, M. A. [Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0304 (United States); Kizilkaya, Orhan [Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, Louisiana 70806 (United States)

2010-01-15

287

Development of Advanced Stirling Radioisotope Generator for Space Exploration  

NASA Astrophysics Data System (ADS)

Under the joint sponsorship of the Department of Energy and NASA, a radioisotope power system utilizing Stirling power conversion technology is being developed for potential future space missions. The higher conversion efficiency of the Stirling cycle compared with that of Radioisotope Thermoelectric Generators (RTGs) used in previous missions (Viking, Pioneer, Voyager, Galileo, Ulysses, Cassini, and New Horizons) offers the advantage of a four-fold reduction in PuO2 fuel, thereby saving cost and reducing radiation exposure to support personnel. With the advancement of state-of-the-art Stirling technology development under the NASA Research Announcement (NRA) project, the Stirling Radioisotope Generator program has evolved to incorporate the advanced Stirling convertor (ASC), provided by Sunpower, into an engineering unit. Due to the reduced envelope and lighter mass of the ASC compared to the previous Stirling convertor, the specific power of the flight generator is projected to increase from 3.5 We/kg to 7 We/kg, along with a 25% reduction in generator length. Modifications are being made to the ASC design to incorporate features for thermal, mechanical, and electrical integration with the engineering unit. These include the heat collector for hot end interface, cold-side flange for waste heat removal and structural attachment, and piston position sensor for ASC control and power factor correction. A single-fault tolerant, active power factor correction controller is used to synchronize the Stirling convertors, condition the electrical power from AC to DC, and to control the ASCs to maintain operation within temperature and piston stroke limits. Development activities at Sunpower and NASA Glenn Research Center (GRC) are also being conducted on the ASC to demonstrate the capability for long life, high reliability, and flight qualification needed for use in future missions.

Chan, Jack; Wood, J. Gary; Schreiber, Jeffrey G.

2007-01-01

288

Boron impregnation treatment of Eucalyptus grandis wood  

Microsoft Academic Search

Eucalyptus grandis is suitable for small timber purposes, but its wood is reported to be non-durable and difficult to treat. Boron compounds being diffusible, and the vacuum-pressure impregnation (VPI) method being more suitable for industrial-scale treatment, the possibility of boron impregnation of partially dry to green timber was investigated using a 6% boric acid equivalent (BAE) solution of boric acid

T. K. Dhamodaran; R. Gnanaharan

2007-01-01

289

Boronizing from paste with furnace heating  

Microsoft Academic Search

1.For boronizing from paste with furnace heating we have developed a coating based on aluminum oxide that gives reliable protection of the surface against penetration of oxygen and the outflow of boron-containing gases.2.The protective coating can be used for local protection of surfaces against saturation with various elements during chemicothermal treatment and also against oxidation of decarburizing of the surfaces

M. I. Bayazitov; V. A. Volkov; A. A. Aliev

1976-01-01

290

Boron isotope variations in nature: a synthesis  

Microsoft Academic Search

The large relative mass difference between the two stable isotopes of boron, 10B and 11B, and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes. Published 11B values (relative to the NBS SRM-951 standard) span a wide range of 90. The lowest 11B values around — 30 are reported for non-marine evaporite minerals and certain

S. Barth

1993-01-01

291

Interstitial defects involving boron in irradiated silicon  

Microsoft Academic Search

Silicon containing high concentrations of boron has been irradiated with 2 MeV electrons at room temperature. Initially, substitutional boron atoms are displaced into interstitial sites, but with prolonged irradiation there is a further interaction between B(i) and an intrinsic defect which is believed to be the Si(i). A similar effect is found in n0-irradiated samples. A broad absorption band is

K. Laithwaite; R. C. Newman; D. H. J. Totterdell

1975-01-01

292

Abrasive slurry composition for machining boron carbide  

DOEpatents

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

Duran, E.L.

1984-11-29

293

Abrasive slurry composition for machining boron carbide  

DOEpatents

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

Duran, Edward L. (Santa Fe, NM)

1985-01-01

294

[Role of radioisotopic lymphoscintigraphy in postphlebitic syndrome of the legs].  

PubMed

Post-phlebitis syndrome of the lower limbs is a set of symptoms that follow a state of phlebostasis and phlebolymphostasis with consequent oedema and tissue distress. We submitted 36 patients with post-phlebitis syndrome of the lower limbs to radioisotopic lymphoscintigraphy for the purposes of evaluating the vicariant function of the lymphatic system and the possible role of the lymphatic system in the genesis of dermo-epidermal abnormalities. The average age of the patients was 53.2 years (range: 43-69 years; M:F ratio: 0.50). The control group consisted of 6 healthy subjects. The average duration of the post-phlebitis syndrome in the patients studied was 8.5 years. We excluded from the study patients in whom a central cause was identified as being responsible for the pathogenisis of the oedema of the lower limbs. In addition, patients with obliterant arteriopathy were also excluded. Venous pathology was evaluated first clinically and then investigated by continuous-wave Doppler. As a first step, venous pressure was measured by Doppler phlebomanometry in clino- and orthostatism. All patients underwent radioisotopic lymphoscintigraphy with microcolloids using the Rijke technique. Radioactivity was monitored by means of a computerized gamma-camera. We classified the pathological findings of radioisotopic lymphoscintigraphy as follows: 1) delayed transit; 2) obstacles; 3) star-shaped superficial collateral lymphatic circulations; 4) lymphocoele or cutaneous lakes. A significant difference was detected (p < 0.05) between the pressure values in the post- phlebitis lower limbs and the pressure values in normal subjects. Combining the results of our measurements we recorded delayed transit in 5 patients (69.5%). This latter group included the cases with the severest forms of post-phlebitis syndrome. Therefore, better knowledge of the pathophysiology of the lymphatic system would appear to be useful in order to understand the origin and evolution of oedema of the lower limbs of patients with post-phlebitis syndrome. To this end, radioisotopic lymphoscintigraphy may be useful as a first-level examination in order to evaluate the capacity and efficiency of the lymphatic system. PMID:11452821

Russo, F; Coscarella, G; Giuliano, G; De Lisa, F; Spina, C; Di Lorenzo, N; Forlini, A; Stolfi, V M; Arturi, A; Manzelli, A; Gaspari, A

2001-01-01

295

Radioisotope bone scanning in a case of sarcoidosis  

SciTech Connect

The application of radioisotope scanning to osseous involvement from systemic sarcoidosis has been infrequently described in the scientific literature. Most commonly, the small bones of the hands and feet are affected if sarcoidosis involves the skeleton. Nonetheless, there are also occasional manifestations of sarcoid in the skull, long bones, and vertebral bodies. This paper describes a case of sarcoid involving the lung parenchyma with multiple lesions in the skull and ribs demonstrated by bone scanning with Tc-99m MDP. Following treatment with steroids, the bone scan showed complete resolution of the rib lesions and almost complete resolution of the lesions in the calvarium.

Cinti, D.C.; Hawkins, H.B.; Slavin, J.D. Jr.

1985-03-01

296

Detection of bone disease in dogs by radioisotope scanning  

E-print Network

DETECTION OZ BONE DISEASE IN DOGS BY RADIOISOTOPE SCANNING A Thesis EARL LOUIS MORRIS Submitted to the Graduate College of Texas A8cM University in partial fulfillment of' the requirement for the degree of MASTER OP SCIENCE May 1971 Major... Subjeotc Veterinary Physiology DETECTION OP BONE DISEASE IN DOGS BY EULDIOISOTOPE SO~NING 4 Thesis EARL LOUIS MORRIS approved as to style and content by: Chairman of Committee Hea of Depa tment Mem er Member Member May 1971 ABSTRACT Detection oi...

Morris, Earl Louis

2012-06-07

297

Perspective of the RIKEN Radioisotope Beam Factory Project  

NASA Astrophysics Data System (ADS)

By coupling the Ring Cyclotron and RIPS fragment separator, RIKEN has performed various studies with fast radio-isotope (RI) beams produced by heavy-ion projectile fragmentation. Various studies on properties of nuclei far from the stability line have been performed with the RI beams. To provide more extended research opportunities, a project to build a new accelerator complex called "RI Beam Factory (RIBF)" has been started. RIBF in its first phase is already under construction, and the first RI beams should be supplied during the year of 2006.

Motobayashi, T.

2004-04-01

298

Radioisotope X-ray fluorescence and neutron activation analyses of the trace element concentrations of the rainbow trout  

NASA Astrophysics Data System (ADS)

The muscles and livers of the ten rainbow trouts ( Oncorhynchus mykiss; N, 1752) obtained from Sapanca, Aquaculture Facility of Aquatic Products Faculty, The University of Istanbul (Turkey), have been analysed quantitatively for some minor elements using the radioisotope energy dispersive X-ray fluorescence (EDXRF) and neutron activation analysis (NAA) methods. It was found that samples contain Na, K, Ca, Sc, Cs, Fe, Co, Cu, Zn, Se, Br, Rb, Sr, Au, La and Ce in different amounts. Comparison of the results with those of reference river fish samples indicated that agricultural rainbow trout samples from Sapanca region have higher Fe level.

Akyuz, T.; Bassari, A.; Bolcal, C.; Sener, E.; Yildiz, M.; Kucer, R.; Kaplan, Z.; Dogan, G.; Akyuz, S.

1999-01-01

299

Two-dimensional boron monolayer sheets.  

PubMed

Boron, a nearest-neighbor of carbon, is possibly the second element that can possess free-standing flat monolayer structures, evidenced by recent successful synthesis of single-walled and multiwalled boron nanotubes (MWBNTs). From an extensive structural search using the first-principles particle-swarm optimization (PSO) global algorithm, two boron monolayers (?(1)- and ?(1)-sheet) are predicted to be the most stable ?- and ?-types of boron sheets, respectively. Both boron sheets possess greater cohesive energies than the state-of-the-art two-dimensional boron structures (by more than 60 meV/atom based on density functional theory calculation using PBE0 hybrid functional), that is, the ?-sheet previously predicted by Tang and Ismail-Beigi and the g(1/8)- and g(2/15)-sheets (both belonging to the ?-type) recently reported by Yakobson and co-workers. Moreover, the PBE0 calculation predicts that the ?-sheet is a semiconductor, while the ?(1)-, ?(1)-, g(1/8)-, and g(2/15)-sheets are all metals. When two ?(1) monolayers are stacked on top each other, the bilayer ?(1)-sheet remains flat with an optimal interlayer distance of ~3.62 Å, which is close to the measured interlayer distance (~3.2 Å) in MWBNTs. PMID:22816319

Wu, Xiaojun; Dai, Jun; Zhao, Yu; Zhuo, Zhiwen; Yang, Jinlong; Zeng, Xiao Cheng

2012-08-28

300

Secret of formulating a selective etching or cleaning solution for boron nitride (BN) thin film  

NASA Astrophysics Data System (ADS)

Boron nitride thin film has a very unique characteristic of extremely high chemical inertness. Thus, it is a better hard mask than silicon nitride for aggressive etching solutions, such as the isotropic HF/HNO3/CH3COOH (or HNA) etchant for silicon. However, because of its high chemical inertness, it is also difficult to remove it. Plasma etching with Freon gases can etch the boron nitride film, but it is unselective to silicon, silicon dioxide or silicon nitride. Cleaning up the boron nitride film with plasma etching will usually leave a damaged or foggy surface. A special wet chemical solution has been developed for etching or cleaning boron nitride film selectively. It can etch boron nitride, but not the coatings or substrates of silicon, silicon nitride and silicon dioxide. It is a very strong oxidizing agent consisting of concentrated sulfuric acid (H2SO4) and hydrogen peroxide (H2O2), but different from the common Piranha Etch. It may be even more interesting to understand the logic or secret behind of how to formulate a new selective etching solution. Various chemical and chemical engineering aspects were considered carefully in our development process. These included creating the right electrochemical potential for the etchant, ensuring large differences in chemical kinetics to make the reactions selective, providing proper mass transfer for removing the by products, etc.

Hui, Wing C.

2004-04-01

301

Potential rare earth free permanent magnet: interstitial boron doped FeCo  

NASA Astrophysics Data System (ADS)

Using the full potential linearized augmented plane wave method, we investigated the structural and the magnetic properties of boron doped FeCo. After fully relaxing the lattice structure, the interatomic distances between boron and Fe atoms were found to be greatly enhanced and the tetragonal distortion was realized due to this increased interatomic distance. Nonetheless, both the unit cell volume and the total magnetic moment of the tetragonally distorted FeCo structure were weakly suppressed compared with those of ideal bulk FeCo. We found a magnetocrystalline anisotropy constant of 0.8 MJ m-3 and this was mainly due to the tetragonal distortion induced by boron impurity, not from the hybridization effect with Fe or Co, because no essential change in the magnetocrystalline anisotropy constant was found even without boron impurity in the lattice distorted system. Additionally, the estimated maximum energy product and coercive field were 100 MGOe and 745 kA m-1, respectively. These results may imply that the interstitial boron doped FeCo can be used for a potential rare earth free permanent magnet although those values are likely to be suppressed in real samples due to micromagnetic factors.

Khan, Imran; Hong, Jisang

2014-10-01

302

Boron stress responsive microRNAs and their targets in barley.  

PubMed

Boron stress is an environmental factor affecting plant development and production. Recently, microRNAs (miRNAs) have been found to be involved in several plant processes such as growth regulation and stress responses. In this study, miRNAs associated with boron stress were identified and characterized in barley. miRNA profiles were also comparatively analyzed between root and leave samples. A total of 31 known and 3 new miRNAs were identified in barley; 25 of them were found to respond to boron treatment. Several miRNAs were expressed in a tissue specific manner; for example, miR156d, miR171a, miR397, and miR444a were only detected in leaves. Additionally, a total of 934 barley transcripts were found to be specifically targeted and degraded by miRNAs. In silico analysis of miRNA target genes demonstrated that many miRNA targets are conserved transcription factors such as Squamosa promoter-binding protein, Auxin response factor (ARF), and the MYB transcription factor family. A majority of these targets were responsible for plant growth and response to environmental changes. We also propose that some of the miRNAs in barley such as miRNA408 might play critical roles against boron exposure. In conclusion, barley may use several pathways and cellular processes targeted by miRNAs to cope with boron stress. PMID:23555702

Ozhuner, Esma; Eldem, Vahap; Ipek, Arif; Okay, Sezer; Sakcali, Serdal; Zhang, Baohong; Boke, Hatice; Unver, Turgay

2013-01-01

303

Boron site preference in ternary Ta and Nb boron silicides  

SciTech Connect

X-ray single crystal (XSC) and neutron powder diffraction data (NPD) were used to elucidate boron site preference for five ternary phases. Ta{sub 3}Si{sub 1-x}B{sub x} (x=0.112(4)) crystallizes with the Ti{sub 3}P-type (space group P4{sub 2}/n) with B-atoms sharing the 8g site with Si atoms. Ta{sub 5}Si{sub 3-x} (x=0.03(1); Cr{sub 5}B{sub 3}- type) crystallizes with space group I4/mcm, exhibiting a small amount of vacancies on the 4a site. Both, Ta{sub 5}(Si{sub 1-x}B{sub x}){sub 3}, x=0.568(3), and Nb{sub 5}(Si{sub 1-x}B{sub x}){sub 3}, x=0.59(2), are part of solid solutions of M{sub 5}Si{sub 3} with Cr{sub 5}B{sub 3}-type into the ternary M-Si-B systems (M=Nb or Ta) with B replacing Si on the 8h site. The D8{sub 8}-phase in the Nb-Si-B system crystallizes with the Ti{sub 5}Ga{sub 4}-type revealing the formula Nb{sub 5}Si{sub 3}B{sub 1-x} (x=0.292(3)) with B partially filling the voids in the 2b site of the Mn{sub 5}Si{sub 3} parent type. - Graphical abstract: The crystal structures of a series of compounds have been solved from X-ray single crystal diffractometry revealing details on the boron incorporation. Highlights: Black-Right-Pointing-Pointer Structure of a series of compounds have been solved by X-ray single crystal diffractometry. Black-Right-Pointing-Pointer Ta{sub 3}(Si{sub 1-x}B{sub x}) (x=0.112) crystallizes with the Ti{sub 3}P-type, B and Si atoms randomly share the 8g site. Black-Right-Pointing-Pointer Structure of Nb{sub 5}Si{sub 3}B{sub 1-x} (x=0.292; Ti{sub 5}Ga{sub 4}-type) was solved from NPD.

Khan, Atta U. [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Nunes, Carlos A. [Escola de Engenharia de Lorena (EEL), Universidade de Sao Paulo (USP), Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12602-810 Lorena, SP (Brazil); Coelho, Gilberto C. [Escola de Engenharia de Lorena (EEL), Universidade de Sao Paulo (USP), Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12602-810 Lorena, SP (Brazil); Mestrado Profissional em Materiais, Centro Universitario de Volta Redonda, Av. Paulo Erlei Alves Abrantes 1325, 27240-560 Volta Redonda-RJ (Brazil); Suzuki, Paulo A. [Escola de Engenharia de Lorena (EEL), Universidade de Sao Paulo (USP), Polo Urbo-Industrial Gleba AI-6, Caixa Postal 116, 12602-810 Lorena, SP (Brazil); Grytsiv, Andriy [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria); Bourree, Francoise [Laboratoire L. Brillouin, CEA/Saclay, F-91191 Gif sur Yvette (France); Giester, Gerald [Institute of Mineralogy and Crystallography, University of Vienna, Althanstrasse14, A-1090 Wien (Austria); Rogl, Peter F., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien (Austria)

2012-06-15

304

Strontium iodide instrument development for gamma spectroscopy and radioisotope identification  

NASA Astrophysics Data System (ADS)

Development of the Europium-doped Strontium Iodide scintillator, SrI2(Eu2+), has progressed significantly in recent years. SrI2(Eu2+) has excellent material properties for gamma ray spectroscopy: high light yield (<80,000 ph/MeV), excellent light yield proportionality, and high effective atomic number (Z = 49) for high photoelectric cross-section. High quality 1.5" and 2" diameter boules are now available due to rapid advances in SrI2(Eu) crystal growth. In these large SrI2(Eu) crystals, optical self-absorption by Eu2+ degrades the energy resolution as measured by analog electronics, but we mitigate this effect through on-the-fly correction of the scintillation pulses by digital readout electronics. Using this digital correction technique we have demonstrated energy resolution of 2.9% FWHM at 662 keV for a 4 in3 SrI2(Eu) crystal, over 2.6 inches long. Based on this digital readout technology, we have developed a detector prototype with greatly improved radioisotope identification capability compared to Sodium Iodide, NaI(Tl). The higher resolution of SrI2(Eu) yields a factor of 2 to 5 improvement in radioisotope identification (RIID) error rate compared to NaI(Tl).

Beck, P. R.; Cherepy, N. J.; Payne, S. A.; Swanberg, E. L.; Nelson, K. E.; Thelin, P. A.; Fisher, S. E.; Hunter, S.; Wihl, B. M.; Shah, K. S.; Hawrami, R.; Burger, A.; Boatner, L. A.; Momayezi, M.; Stevens, K. T.; Randles, M. H.; Solodovnikov, D.

2014-09-01

305

Technology Development for a Stirling Radioisotope Power System  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center and the Department of Energy are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA Glenn is addressing key technology issues through the use of two NASA Phase II SBIRs with Stirling Technology Company (STC) of Kennewick, WA. Under the first SBIR, STC demonstrated a synchronous connection of two thermodynamically independent free-piston Stirling convertors and a 40 to 50 fold reduction in vibrations compared to an unbalanced convertor. The second SBIR is for the development of an Adaptive Vibration Reduction System (AVRS) that will essentially eliminate vibrations over the mission lifetime, even in the unlikely event of a failed convertor. This paper presents the status and results for these two SBIR projects and also discusses a new NASA Glenn in-house project to provide supporting technology for the overall Stirling radioisotope power system development. Tasks for this new effort include convertor performance verification, controls development, heater head structural life assessment, magnet characterization and thermal aging tests, FEA analysis for a lightweight alternator concept, and demonstration of convertor operation under launch and orbit transfer load conditions.

Thieme, Lanny G.; Qiu, Songgang; White, Maurice A.

2000-01-01

306

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140° C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G.

2009-03-01

307

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling convertor. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G.

2009-01-01

308

Sodium Variable Conductance Heat Pipe for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

In a Stirling radioisotope system, heat must continually be removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the converter stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, and also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) has been designed to allow multiple stops and restarts of the Stirling convertor in an Advanced Stirling Radioisotope Generator (ASRG). When the Stirling convertor is turned off, the VCHP will activate when the temperatures rises 30 C above the setpoint temperature. A prototype VCHP with sodium as the working fluid was fabricated and tested in both gravity aided and against gravity conditions for a nominal heater head temperature of 790 C. The results show very good agreement with the predictions and validate the model. The gas front was located at the exit of the reservoir when heater head temperature was 790 C while cooling was ON, simulating an operating Advanced Stirling Converter (ASC). When cooling stopped, the temperature increased by 30 C, allowing the gas front to move past the radiator, which transferred the heat to the case. After resuming the cooling flow, the front returned at the initial location turning OFF the VCHP. The against gravity working conditions showed a colder reservoir and faster transients.

Tarau, Calin; Anderson, William G.; Walker, Kara

2009-01-01

309

Industrial radiation and radioisotope gauging techniques and applications  

SciTech Connect

The radiation and radioisotope gauging industry in the United States has primarily followed a path of development solely by the private sector. It has remained highly proprietary in nature, which is opposite to the path taken by many other countries. In other countries radiation gauge development has been controlled in large part by government-sponsored research and development, which has spawned many more publications in the open literature. Historically, some of the leaders have been Great Britain, Poland, France, Russia, and Australia. This has possibly led to the misconception that the development of this technology is being dominated by countries outside the United States. This is not a healthy situation-it would be good to see our industry begin to publish more in the open literature and to sponsor more research at universities. In efforts to promote more open-literature publication, the American Nuclear Society (ANS) sponsored a topical meeting on Industrial Radiation and Radioisotope Measurement Applications (IRRMA) in 1988 that was held again in 1992.

Gardner, R.P. [North Carolina State Univ., Raleigh, NC (United States)

1997-12-01

310

Between Medicine and Industry: Medical Physics and the Rise of the Radioisotope 1945–65  

Microsoft Academic Search

This article explores the development of clinical uses for the artificial radioisotope between 1945 and 1965. As part of the broader nuclear enterprise, the radioisotope programme enjoyed powerful political and financial support from the British government. In 1945, medical uses for artificial radioactivity remained highly experimental, yet in less than two decades its application in imaging technologies formed a mainstay

Alison Kraft

2006-01-01

311

Coated particle fuel for radioisotope power systems and heater units: status and future research needs  

Microsoft Academic Search

Coated particle fuel has been proposed recently for use in Radioisotope Power Systems (RPSs) and Radioisotope Heater Units (RHUs) for a variety of space missions requiring power levels from mWs to 10’s or even hundreds of Watts. It can be made into different shapes and sizes of solid compacts, heating tapes, or paints. Using a conservative design approach, this fuel

Mohamed S. El-Genk; Jean-Michel Tournier; Ronald J. Lipinski

2000-01-01

312

Coated particle fuel for radioisotope power systems and heater units: status and future research needs  

Microsoft Academic Search

Coated particle fuel has been proposed recently for use in Radioisotope Power Systems (RPSs) and Radioisotope Heater Units (RHUs) for a variety of space missions requiring power levels from mWs to 10's or even hundreds of Watts. It can be made into different shapes and sizes of solid compacts, heating tapes, or paints. Using a conservative design approach, this fuel

Mohamed S. El-Genk; Jean-Michel Tournier; Joseph A. Sholtis; Ronald J. Lipinski

2000-01-01

313

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

314

Femtosecond-laser-induced destruction of boron-nitride nanotubes and boron-nitride doped graphene  

NASA Astrophysics Data System (ADS)

By means of first principles calculations we studied the intense femtosecond-laser excitation of several boron­ nitride nanotubes and a boron-nitride doped graphene layer up to irradiation levels where these structures disintegrate. We performed molecular dynamics simulations using our in-house Code for Highly excited Valence Electron Systems (CHIVES). For different boron-nitride nanotubes we determined the damage threshold in terms of the electronic temperature and the absorbed energy per atom. We found that all nanotubes studied were destroyed in the first 200 fs after an ultrafast laser excitation heating the electrons to 108 mHa (34103 K). Some tubes also disintegrated at lower electronic temperatures. For the boron-nitride doped graphene we found that at a laser-induced electronic temperature of 100 mHa (31577 K) bonds break and the boron-nitride dimer leaves the structure.

Bauerhenne, Bernd; Eschstruth, Nils; Zijlstra, Eeuwe S.; Garcia, Martin E.

2013-11-01

315

Spatial Burnout in Water Reactors with Nonuniform Startup Distributions of Uranium and Boron  

NASA Technical Reports Server (NTRS)

Spatial burnout calculations have been made of two types of water moderated cylindrical reactor using boron as a burnable poison to increase reactor life. Specific reactors studied were a version of the Submarine Advanced Reactor (sAR) and a supercritical water reactor (SCW) . Burnout characteristics such as reactivity excursion, neutron-flux and heat-generation distributions, and uranium and boron distributions have been determined for core lives corresponding to a burnup of approximately 7 kilograms of fully enriched uranium. All reactivity calculations have been based on the actual nonuniform distribution of absorbers existing during intervals of core life. Spatial burnout of uranium and boron and spatial build-up of fission products and equilibrium xenon have been- considered. Calculations were performed on the NACA nuclear reactor simulator using two-group diff'usion theory. The following reactor burnout characteristics have been demonstrated: 1. A significantly lower excursion in reactivity during core life may be obtained by nonuniform rather than uniform startup distribution of uranium. Results for SCW with uranium distributed to provide constant radial heat generation and a core life corresponding to a uranium burnup of 7 kilograms indicated a maximum excursion in reactivity of 2.5 percent. This compared to a maximum excursion of 4.2 percent obtained for the same core life when w'anium was uniformly distributed at startup. Boron was incorporated uniformly in these cores at startup. 2. It is possible to approach constant radial heat generation during the life of a cylindrical core by means of startup nonuniform radial and axial distributions of uranium and boron. Results for SCW with nonuniform radial distribution of uranium to provide constant radial heat generation at startup and with boron for longevity indicate relatively small departures from the initially constant radial heat generation distribution during core life. Results for SAR with a sinusoidal distribution rather than uniform axial distributions of boron indicate significant improvements in axial heat generation distribution during the greater part of core life. 3. Uranium investments for cylindrical reactors with nonuniform radial uranium distributions which provide constant radial heat generation per unit core volume are somewhat higher than for reactors with uniform uranium concentration at startup. On the other hand, uranium investments for reactors with axial boron distributions which approach constant axial heat generation are somewhat smaller than for reactors with uniform boron distributions at startup.

Fox, Thomas A.; Bogart, Donald

1955-01-01

316

Hypoxia-selective compounds for boron neutron capture therapy  

E-print Network

Boron neutron capture therapy (BNCT) is a biochemically targeted form of radiotherapy for cancer. In BNCT, a compound labeled with the stable isotope boron-10 is systemically administered, and tumor cells selectively uptake ...

Shah, Jungal (Jugal Kaushik)

2008-01-01

317

Utilization of borogypsum as set retarder in Portland cement production  

Microsoft Academic Search

Boron ores are used in the production of various boron compounds such as boric acid, borax and boron oxide. Boric acid is produced by reacting colemanite(2CaO·3B2O3·5H2O) with sulphuric acid and a large quantity of borogypsum is formed during this production. This waste causes various environmental problems when discharged directly to the environment. Portland cement is the most important material in

Recep Boncukcuo?lu; M. Tolga Y?lmaz; M. Muhtar Kocakerim; Vahdettin Tosuno?lu

2002-01-01

318

Boron nitride nanotubes and nanosheets.  

PubMed

Hexagonal boron nitride (h-BN) is a layered material with a graphite-like structure in which planar networks of BN hexagons are regularly stacked. As the structural analogue of a carbon nanotube (CNT), a BN nanotube (BNNT) was first predicted in 1994; since then, it has become one of the most intriguing non-carbon nanotubes. Compared with metallic or semiconducting CNTs, a BNNT is an electrical insulator with a band gap of ca. 5 eV, basically independent of tube geometry. In addition, BNNTs possess a high chemical stability, excellent mechanical properties, and high thermal conductivity. The same advantages are likely applicable to a graphene analogue-a monatomic layer of a hexagonal BN. Such unique properties make BN nanotubes and nanosheets a promising nanomaterial in a variety of potential fields such as optoelectronic nanodevices, functional composites, hydrogen accumulators, electrically insulating substrates perfectly matching the CNT, and graphene lattices. This review gives an introduction to the rich BN nanotube/nanosheet field, including the latest achievements in the synthesis, structural analyses, and property evaluations, and presents the purpose and significance of this direction in the light of the general nanotube/nanosheet developments. PMID:20462272

Golberg, Dmitri; Bando, Yoshio; Huang, Yang; Terao, Takeshi; Mitome, Masanori; Tang, Chengchun; Zhi, Chunyi

2010-06-22

319

Copper and boron fixation in wood by pyrolytic resins.  

PubMed

A phenol-formaldehyde (PF)-resin designed to penetrate wood and immobilize copper and boron in wood cells for protection against decay was investigated. The phenol portion of the PF-resin was partially substituted with pyrolysis oil derived from softwood bark. The objective was to reduce the environmental impact associated with the production of petroleum-borne phenol, as well as to improve the product economics. Leaching tests were conducted with three different formulas of resins containing 50%, 75% or 85% by weight of pyrolytic oil on a total phenol basis. The leachates were analyzed for the presence of copper by atomic absorption spectroscopy while inductively coupled plasma spectroscopy was used for boron detection. Copper leaching was reduced up to 18 times when comparing the treatments with and without the resin. Preservative leaching varied between wood species as well as between the resins containing different concentrations of pyrolytic oil. The organic leachates were measured using gas chromatography and mass spectroscopy. Trace amounts of organics, mostly acetic acid, were found in the leachates. PMID:18835155

Mourant, Daniel; Yang, Dian-Qing; Lu, Xiao; Riedl, Bernard; Roy, Christian

2009-02-01

320

Production, distribution and applications of californium-252 neutron sources.  

PubMed

The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations. PMID:11003521

Martin, R C; Knauer, J B; Balo, P A

2000-01-01

321

Characterization of boron carbide with an electron microprobe  

NASA Technical Reports Server (NTRS)

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.

Matteudi, G.; Ruste, J.

1983-01-01

322

Investigations on boron levels in drinking water sources in China  

Microsoft Academic Search

To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking\\u000a water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples\\u000a from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results\\u000a showed that boron existed in

Ren-ji Xu; Xiao-ru Xing; Qun-fang Zhou; Gui-bin Jiang; Fu-sheng Wei

2010-01-01

323

Energy from Boron and Non-nuclear Metallic Fuels  

Microsoft Academic Search

This study aims to obtain the energy from elemental boron burning as solid fuel, which is synthesized from boron minerals, aluminum, iron, and their substances. To obtain the elemental boron from borax, first boric acid (H3BO3) was obtained from borax decahydrate by using HCl or H2SO4. The boric acid was converted to boron oxide by dehydration process. For reducing the

A. Demirbas

2008-01-01

324

Role of Boron in Plant Growth and its Transport Mechanisms  

Microsoft Academic Search

\\u000a In the last decade, molecular understandings of boron transport and boron function in plants have greatly advanced. Crosslinking\\u000a of pectic polysaccharide rhamonogalacturonan-II (RG-II) via boron was shown to be essential for normal plant growth. Two types\\u000a of boron (B) transport molecules, BORs and NIPs, localized to plasma membrane were identified from Arabidopsis thaliana. BOR1 was identified as the first borate\\/boric

Kyoko Miwa; Toru Fujiwara

325

Microdosimetry for boron neutron capture therapy.  

PubMed

Preclinical studies for boron neutron capture therapy (BNCT) using epithermal neutrons are ongoing at several laboratories. The absorbed dose in tumor cells is a function of the thermal neutron flux at depth, the microscopic boron concentration, and the size of the cell. Dosimetry is therefore complicated by the admixture of thermal, epithermal, and fast neutrons, plus gamma rays, and the array of secondary high-linear-energy-transfer particles produced within the patient from neutron interactions. Microdosimetry can be a viable technique for determining absorbed dose and radiation quality. A 2.5-cm-diameter tissue-equivalent gas proportional counter has been built with 50 parts per million (ppm) 10B incorporated into the walls and counting gas to simulate the boron uptake anticipated in tumors. Measurements of lineal energy (y) spectra for BNCT in simulated volumes of 1-10 microns diameter show a dose enhancement factor of 4.3 for 30 ppm boron, and a "y" of 250 keV/microns for the boron capture process. Chamber design plus details of experimental and calculated linear energy spectra will be presented. PMID:1594762

Wuu, C S; Amols, H I; Kliauga, P; Reinstein, L E; Saraf, S

1992-06-01

326

Unilamellar liposomes with enhanced boron content.  

PubMed

A new type of boron-rich, DSPC-free, unilamellar liposomes was formed using the novel dual-chain, ionic, nido-carborane lipid, K[nido-7-(C16H33OCH2)2CHOCH2-7,8-C2B9H11] (DAC-16), and cholesterol for encapsulation of an aqueous buffer core. Since DSPC was not necessary for the formation of stable DAC-16 liposomes, the boron concentration of these vesicles was increased dramatically to approximately 8.8 wt % in the dry lipid; these liposomes had a high bilayer boron incorporation efficiency of 98%. DSPC-free liposomes exhibited a size distribution pattern of 40-60 nm, which was in the range normally associated with selective tumor uptake. This size distribution was maintained throughout storage at room temperature for several months. Additionally, optimized liposome formulations incorporating DAC-16, DSPC, and cholesterol were identified having stable size distribution patterns after storage for more than two months at a variety of temperatures. Although animal studies indicate that DAC-16 liposomes are toxic, this new ionic nido-carborane lipid allows the formation of liposomes of high boron content for in vitro applications that require the delivery of large amounts of boron. PMID:16417247

Li, Tiejun; Hamdi, Julie; Hawthorne, M Frederick

2006-01-01

327

Space radioisotope power source requirements update and technology status  

SciTech Connect

The requirements for a space advanced radioisotope power source are based on potential deep space missions being investigated for the NASA Advanced Space Systems Development Program. Since deep space missions have not been approved, updating requirements is a continuos parallel process of designing the spacecraft and the science instruments to accomplish the potential missions and developing the power source technology to meet changing requirements. There are at least two potential missions, Pluto/Kuiper Express and Europa Orbiter, which may require space advanced radioisotope power sources. The Europa Orbiter has been selected as the preferred first potential mission. However the final decision will depend on the technology readiness of all the subsystems and the project must be able to switch to Pluto Kuiper Express as the first mission as late as the beginning of fiscal year 2000. Therefore the requirements for the power source will cover both potential missions. As the deep space spacecraft design evolves to meet the science requirements and the Alkali Metal Thermal to Electric (AMTEC) technology matures the advanced radioisotope power source design requirements are updated The AMTEC technology developed to date uses stainless steel for the sodium containment material. The higher efficiency required for the space power system dictates that the AMTEC technology must operate at a higher temperature than possible with stainless steel. Therefore refractory materials have been selected as the baseline material for the AMTEC cell. These refractory materials are Nb1Zr for the hot side and Nb1Zr or Nb10Hf1Ti for the cold side. These materials were selected so the AMTEC cell can operate at 1150K to 1350K hot side temperature and 600K to 700K cold side temperature and meet the present power and mass requirements using four to six general purpose heat source modules as the heat source. The new containment materials and brazes will be evaluated as to lifetime, compatibility and performance with the AMTEC beta prime Alumina, the TiN electrodes, the sodium and the molybdenum current collectors. AMTEC cell components and cells will be built with the baseline containment materials and brazes and tested to determine the performance as a function of temperature. These containment materials will be also be tested with all the other AMTEC components to determine acceleration factors needed to predict AMTEC performance degradation and failure as a function of operating time at temperature.

Mondt, J.F.

1998-07-01

328

Utilizing Radioisotope Power System Waste Heat for Spacecraft Thermal Management  

NASA Technical Reports Server (NTRS)

An advantage of using a Radioisotope Power System (RPS) for deep space or planetary surface missions is the readily available waste heat, which can be used for a number of beneficial purposes including: maintaining electronic components within a controlled temperature range, warming propulsion tanks and mobility actuators, and maintaining liquid propellants above their freezing temperature. Previous missions using Radioisotope Thermoelectric Generators (RTGs) dissipated large quantities of waste heat due to the low efficiency of the thermoelectric conversion technology. The next generation RPSs, such as the 110-Watt Stirling Radioisotope Generator (SRG110) will have higher conversion efficiencies, thereby rejecting less waste heat at a lower temperature and may require alternate approaches to transferring waste heat to the spacecraft. RTGs, with efficiencies of 6 to 7 percent, reject their waste heat at the relatively high heat rejection temperature of 200 C. This is an advantage when rejecting heat to space; however, transferring heat to the internal spacecraft components requires a large and heavy radiator heat exchanger. At the same time, sensitive spacecraft instruments must be shielded from the thermal radiation of the RTG. The SRG110, with an efficiency around 22 percent and 50 C nominal housing surface temperature, can readily transfer the available waste heat directly via heat pipes, thermal straps, or fluid loops. The lower temperatures associated with the SRG110 avoid the chances of overheating other scientific components, eliminating the need for thermal shields. This provides the spacecraft designers more flexibility when locating the generator for a specific mission. A common misconception with high-efficiency systems is that there is not enough waste heat for spacecraft thermal management. This paper will dispel this misconception and investigate the use of a high-efficiency SRG110 for spacecraft thermal management and outline potential methods of waste heat utilization in several conceptual missions (Lunar Rover, Mars Rover, and Titan Lander). The advantages associated with the SRG110 as they relate to ease of assembly, less complex interfaces, and overall mass savings for a spacecraft will be highlighted.

Pantano, David R.; Dottore, Frank; Tobery, E. Wayne; Geng, Steven M.; Schreiber, Jeffrey G.; Palko, Joseph L.

2005-01-01

329

The Modification of Polyurethane Foams Using New Boroorganic Polyols (II) Polyurethane Foams from Boron-Modified Hydroxypropyl Urea Derivatives  

PubMed Central

The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150°C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

2014-01-01

330

The modification of polyurethane foams using new boroorganic polyols (II) polyurethane foams from boron-modified hydroxypropyl urea derivatives.  

PubMed

The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrogen and boron impacts on the foams' properties were discussed, for instance, on their physical, mechanical, and electric properties. Boron presence causes improvement of dimensional stability and thermal stability of polyurethane foams. They can be applied even at temperature 150 °C. Unfortunately, introducing boron in polyurethanes foams affects deterioration of their water absorption, which increases as compared to the foams that do not contain boron. However, presence of both boron and nitrogen determines the decrease of the foams combustibility. Main impact on the decrease combustibility of the obtained foams has nitrogen presence, but in case of proper boron and nitrogen ratio their synergic activity on the combustibility decrease can be easily seen. PMID:24587721

Zarzyka, Iwona

2014-01-01

331

Theoretical dosimetry estimations for radioisotopes produced by proton-induced reactions on natural and enriched molybdenum targets.  

PubMed

This study presents a summary of the dosimetry calculations performed for three technetium agents most commonly used in nuclear medicine diagnostic studies, namely sestamibi™, phosphonates and pertechnetate, labeled with cyclotron-produced technetium. Calculated patient doses were compared to those that would be delivered by the same radiotracers labeled with technetium obtained from a generator produced in a reactor. The main difference is that technetium from a generator is pure, i.e. contains only (99m)Tc and its decay product (99g)Tc, while in a cyclotron a large number of other stable and radioactive isotopes are created. In our calculations only technetium radioisotopes (ground and isomeric states) were considered as they will be included in the radiotracer labeling process and will contribute to the patient dose. Other elements should be removed by chemical purification. These dose estimates are based on our theoretical calculations of the proton-induced reaction cross sections and radioisotope production yields. Thick targets of enriched (three different compositions) and natural molybdenum, and three initial beam energies (16, 19 and 24 MeV) were considered for irradiation times of 3, 6 and 12 h with a beam current of 200 µA. The doses were calculated for injection times corresponding to 0, 2, 8, 12 and 24 h after the end of beam. PMID:22391011

Hou, X; Celler, A; Grimes, J; Bénard, F; Ruth, T

2012-03-21

332

Theoretical dosimetry estimations for radioisotopes produced by proton-induced reactions on natural and enriched molybdenum targets  

NASA Astrophysics Data System (ADS)

This study presents a summary of the dosimetry calculations performed for three technetium agents most commonly used in nuclear medicine diagnostic studies, namely sestamibi™, phosphonates and pertechnetate, labeled with cyclotron-produced technetium. Calculated patient doses were compared to those that would be delivered by the same radiotracers labeled with technetium obtained from a generator produced in a reactor. The main difference is that technetium from a generator is pure, i.e. contains only 99mTc and its decay product 99gTc, while in a cyclotron a large number of other stable and radioactive isotopes are created. In our calculations only technetium radioisotopes (ground and isomeric states) were considered as they will be included in the radiotracer labeling process and will contribute to the patient dose. Other elements should be removed by chemical purification. These dose estimates are based on our theoretical calculations of the proton-induced reaction cross sections and radioisotope production yields. Thick targets of enriched (three different compositions) and natural molybdenum, and three initial beam energies (16, 19 and 24 MeV) were considered for irradiation times of 3, 6 and 12 h with a beam current of 200 µA. The doses were calculated for injection times corresponding to 0, 2, 8, 12 and 24 h after the end of beam.

Hou, X.; Celler, A.; Grimes, J.; Bénard, F.; Ruth, T.

2012-03-01

333

Mechanical and physical properties of modern boron fibers  

NASA Technical Reports Server (NTRS)

Measurements of the Young's modulus, flexural modulus, shear modulus and Poisson's ratio for boron fibers prepared by modern deposition techniques are reported. Physical properties of the boron fibers, including density, thermal expansion and resistance, are also surveyed. In addition, prediction of the total deformation strain in an anelastic boron fiber subjected to tensile or flexural stress is discussed.

Dicarlo, J. A.

1978-01-01

334

Effect of magnesium on the burning characteristics of boron particles  

NASA Astrophysics Data System (ADS)

Boron is an attractive fuel for propellants and explosives because of its high energy density. However, boron particles are difficult to combust because of inhibiting oxide layers that cover the particles. The use of magnesium as additives has been shown to promote boron oxidation. In this study, laser ignition facility and thermobalance were used to investigate the effect of magnesium on the burning characteristics of boron particles. The influences of magnesium addition on sample combustion flame, boron ignition delay time, boron combustion efficiency and initial temperature of boron oxidation. Results show that all Mg/B samples exhibit the same type of flame structure, i.e., a bright plume surrounded by green radiation which is interpreted as BO2 emission. The combustion flame intensity of a sample increases with the increasing magnesium content of boron particles. An increase in magnesium content results in a decrease and a subsequent increase in boron ignition delay time. (Mg/B)0.2 has a minimum ignition delay time of ~48 ms. Boron combustion efficiency increases with increasing magnesium addition. (Mg/B)0.5 shows a maximum boron combustion efficiency of ~64.2%. Magnesium addition decreases the initial temperature of boron oxidation.

Liu, Jian-zhong; Xi, Jian-fei; Yang, Wei-juan; Hu, You-rui; Zhang, Yan-wei; Wang, Yang; Zhou, Jun-hu

2014-03-01

335

Radioisotope cisternography in spontaneous CSF leaks: interpretations and misinterpretations.  

PubMed

A broadening of the clinical and imaging features of the spontaneous cerebrospinal fluid (CSF) leaks is now well recognized, far beyond what was thought only two decades ago. This has resulted in increasing number of patients with atypical and unusual features who, not unexpectedly, are directed to headache specialists and tertiary referral centers. In many cases, obviously the fundamental question of presence or absence of CSF leak will need to be addressed prior to proceeding with further and often more involved, more invasive, and more costly diagnostic and therapeutic considerations. Radioisotope cisternography often proves to be very helpful in these situations by demonstrating reliable, although indirect, evidences of CSF leak while it is less helpful in directly identifying the exact site of the CSF leakage. In this overview article, the expectations from and the limitations of this diagnostic method are described along with some personal observations in the past 25 years. PMID:25041119

Mokri, Bahram

2014-09-01

336

AMTEC radioisotope power system for the Pluto Express mission  

SciTech Connect

The Alkali Metal Thermal to Electric Converter (AMTEC) technology has made substantial advances in the last 3 years through design improvements and technical innovations. In 1993 programs began to produce an AMTEC cell specifically for the NASA Pluto Express Mission. A set of efficiency goals was established for this series of cells to be developed. According to this plan, cell {number_sign}8 would be 17% efficient but was actually 18% efficient. Achieving this goal, as well as design advances that allow the cell to be compact, has resulted in pushing the cell from an unexciting 2 W/kg and 2% efficiency to very attractive 40 W/kg and 18% measured efficiency. This paper will describe the design and predict the performance of a radioisotope powered AMTEC system for the Pluto Express mission.

Ivanenok, J.F. III; Sievers, R.K. [Advanced Modular Power Systems, Inc., Ann Arbor, MI (United States)

1995-12-31

337

RTGs - The powering of Ulysses. [Radio-isotope Thermoelectric Generator  

NASA Technical Reports Server (NTRS)

The radio-isotope thermoelectric generator (RTG) for Ulysses' electronic supply is described noting that lack of sufficient sunlight renders usual solar cell power generation ineffective due to increased distance from sun. The history of the RTG in the U.S.A. is reviewed citing the first RTG launch in 1961 with an electrical output of 2.7 W and the improved Ulysses RTG, which provides 285 W at mission beginning and 250 W at mission end. The RTG concept is discussed including the most recent RTG technology developed by the DOE, the General Purpose Heat Source RTG (GPHS-RTG). The system relies upon heat generated by radioactive decay using radioactive plutonium-238, which is converted directly to energy using the Seebeck method.

Mastal, E. F.; Campbell, R. W.

1990-01-01

338

Biological Evaluation of Boronated Unnatural Amino Acids as New Boron Carriers  

PubMed Central

There is a pressing need for new and more efficient boron delivery agents to tumor cells for use in boron neutron capture therapy (BNCT). A class of boronated unnatural cyclic amino acids has demonstrated a remarkable selectivity toward tumors in animal and cell culture models, far superior to currently used agents in clinical BNCT. One of these amino acids, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC), has shown a tumor to blood ratio of 8 and a tumor to normal brain ratio of nearly 21 in a melanoma bearing mouse model. This work represents further biological characterization of this compound for tumor targeting in an EMT6 murine mammary carcinoma mouse model and a T98G human glioblastoma cell line. Female BALB/c mice bearing EMT6 tumors were injected with the fructose complex form of racemic mixtures of cis- and trans isomers of ABCPC in identical concentrations. Boron concentrations were measured in the tumor, blood, brain, skin, and liver tissues at 1, 3, and 5 hr post injection. These observations revealed a remarkable difference in racemic mixtures of cis and trans isomers in tumor targeting by boron. This implies that further separation of the L and D forms of this compound may enhance tumor targeting to an even higher degree than that provided by the racemic mixtures. Since the uptake measurements were made in homogenized tumor and normal tissues, little is known about the subcellular location of the boron arising from the various isomeric forms of the amino acid. To study subcellular delivery of boron from ABCPC in T98G human glioblastoma cells, we employed secondary ion mass spectrometry (SIMS) based technique of ion microscopy, which is capable of quantitatively imaging isotopic (elemental) gradients in cells and tissues at 500 nm spatial resolution. The T98G cells were exposed to the nutrient medium containing 100 ppm boron equivalent of a mixture of both L and D isomers of ABCPC in the form of a fructose complex for 1 hr. Following this treatment, the cells were fast frozen, freeze-fractured, and freeze-dried for SIMS analysis. Within an hour of exposure, ABCPC provided partitioning of intracellular to extracellular boron of 3/1. SIMS imaging revealed that boron from ABCPC was distributed throughout the cell, including the nucleus. This level of boron delivery within an hour of exposure is superior to p-boronophenylalanine (BPA) and sodium borocaptate (BSH), which have been previously studied by SIMS in the same cell line. These encouraging observations provide compelling support for further isomeric separations of ABCPC into the D and L forms for enhanced tumor targeting and continued testing of these compounds as new boron carriers in BNCT. PMID:19398346

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

2010-01-01

339

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

DOEpatents

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

Halverson, Danny C. (Manteca, CA); Landingham, Richard L. (Livermore, CA)

1988-01-01

340

Accelerator-driven boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

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

Edgecock, Rob

2014-05-01

341

Boron-10 Lined Proportional Counter Model Validation  

SciTech Connect

The Department of Energy Office of Nuclear Safeguards (NA-241) is supporting the project “Coincidence Counting With Boron-Based Alternative Neutron Detection Technology” at Pacific Northwest National Laboratory (PNNL) for the development of an alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a boron-lined proportional tube-based alternative system in the configuration of a coincidence counter. This report discusses the validation studies performed to establish the degree of accuracy of the computer modeling methods current used to simulate the response of boron-lined tubes. This is the precursor to developing models for the uranium neutron coincidence collar under Task 2 of this project.

Lintereur, Azaree T.; Siciliano, Edward R.; Kouzes, Richard T.

2012-06-30

342

Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) was designed to allow multiple stops and restarts of the Stirling engine. A VCHP was designed for the Advanced Stirling Radioisotope Generator, with a 850 °C heater head temperature. The VCHP turns on with a ?T of 30 °C, which is high enough to not risk standard ASRG operation but low enough to save most heater head life. This VCHP has a low mass, and low thermal losses for normal operation. In addition to the design, a proof-of-concept NaK VCHP was fabricated and tested. While NaK is normally not used in heat pipes, it has an advantage in that it is liquid at the reservoir operating temperature, while Na or K alone would freeze. The VCHP had two condensers, one simulating the heater head, and the other simulating the radiator. The experiments successfully demonstrated operation with the simulated heater head condenser off and on, while allowing the reservoir temperature to vary over 40 to 120 °C, the maximum range expected. In agreement with previous NaK heat pipe tests, the evaporator ?T was roughly 70 °C, due to distillation of the NaK in the evaporator.

Anderson, William G.; Tarau, Calin

2008-01-01

343

Pathway of radioisotopes from land surface to sewage sludge  

NASA Astrophysics Data System (ADS)

Radioactive surface contaminations will only partially remain at the original location - a fraction of the inventory will take part in (mainly terrestrial and aquatic) environmental transport processes. The probably best known and most important process comprises the food chain. Besides, the translocation of dissolved and particle-bound radioisotopes with surface waters plays an important role. These processes can have the effect of displacing large radioisotope amounts over considerable distances and of creating new sinks and hot spots, as it is already known for sewage sludge. We are reporting on a combined modeling and experimental project concerning the transport of I-131 and Cs-134/Cs-137 FDNPP 2011 depositions in the Fukushima Prefecture. Well-documented experimental data sets are available for surface deposition and sewage sludge concentrations. The goal is to model the pathway in between, involving surface runoff, transport in the sewer system and processes in the sewage treatment plant. Watershed runoff and sewer transport will be treated with models developed recently by us in other projects. For sewage treatment processes a new model is currently being constructed. For comparison and further validation, historical data from Chernobyl depositions and tracer data from natural and artificial, e.g. medical, isotopes will be used. First results for 2011 data from Fukushima Prefecture will be presented. The benefits of the study are expected to be two-fold: on one hand, the abundant recent and historical data will help to develop and improve environmental transport models; on the other hand, both data and models will help in identifying the most critical points in the envisaged transport pathways in terms of radiation protection and waste management.

Fischer, Helmut W.; Yokoo, Yoshiyuki

2014-05-01

344

Estimation of boron isotope ratios using high resolution continuum source atomic absorption spectrometry  

NASA Astrophysics Data System (ADS)

In the production of 10B enriched steels, the production-recycling process needs to be closely monitored for inadvertent mix-up of materials with different B isotope levels. A quick and simple method for the estimation of boron isotope ratios in high alloyed steels using high resolution continuum source flame AAS (HR-CS-FAAS) was developed. On the 208.9 nm B line the wavelength of the peak absorption of 10B and 11B differs by 2.5 pm. The wavelength of the peak absorption of boron was determined by fitting a Gauss function through spectra simultaneously recorded by HR-CS-FAAS. It was shown that a linear correlation between the wavelength of the peak absorption and the isotope ratio exists and that this correlation is independent of the total boron concentration. Internal spectroscopic standards were used to compensate for monochromator drift and monochromator resolution changes. Accuracy and precision of the analyzed samples were thereby increased by a factor of up to 1.3. Three steel reference materials and one boric acid CRM, each certified for the boron isotope ratio were used to validate the procedure.

Wiltsche, Helmar; Prattes, Karl; Zischka, Michael; Knapp, Günter

2009-04-01

345

Boron neutron capture therapy for glioblastoma.  

PubMed

Boron neutron capture therapy (BNCT) theoretically allows the preferential destruction of tumor cells while sparing the normal tissue, even if the cells have microscopically spread to the surrounding normal brain. The tumor cell-selective irradiation used in this method is dependent on the nuclear reaction between the stable isotope of boron ((10)B) and thermal neutrons, which release alpha and (7)Li particles within a limited path length (-9 microm) through the boron neutron capture reaction, (10)B(n,alpha)(7)Li. Recent clinical studies of BNCT have focused on high-grade glioma and cutaneous melanoma; however, cerebral metastasis of melanoma, anaplastic meningioma, head and neck tumor, and lung and liver metastasis have been investigated as potential candidates for BNCT. To date, more than 350 high-grade gliomas have been treated in BNCT facilities worldwide. Current clinical BNCT trials for glioblastoma (GBM) have used the epithermal beam at a medically optimized research reactor, and p-dihydroxyboryl-phenylalanine (BPA) and/or sulfhydryl borane Na(2)B(12)H(11)SH (BSH) as the boron delivery agent(s). The results from these rather small phase I/II trials for GBM appear to be encouraging, but prospective randomized clinical trials will be needed to confirm the efficacy of this theoretically promising modality. Improved tumor-targeting boron compounds and optimized administration methods, improved boron drug delivery systems, development of a hospital-based neutron source, and/or other combination modalities will enhance the therapeutic effectiveness of BNCT in the future. PMID:18313207

Yamamoto, Tetsuya; Nakai, Kei; Matsumura, Akira

2008-04-18

346

Boron removal by electrocoagulation and recovery.  

PubMed

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. PMID:24412846

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

2014-03-15

347

Liposomal boron delivery for neutron capture therapy.  

PubMed

Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons. The thermal neutrons have an energy of 0.025 eV, clearly below the threshold energy required to ionize tissue components. However, neutron capture by (10)B produces lithium ion and helium (alpha-particles), which are high linear energy transfer (LET) particles, and dissipate their kinetic energy before traveling one cell diameter (5-9 microm) in biological tissues, ensuring their potential for precise cell killing. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer, and hepatoma using two boron compounds: sodium borocaptate (Na(2)(10)B(12)H(11)SH; Na(2)(10)BSH) and l-p-boronophenylalanine (l-(10)BPA). These low molecular weight compounds are cleared easily from the cancer cells and blood. Therefore, high accumulation and selective delivery of boron compounds into tumor tissues are most important to achieve effective BNCT and to avoid damage of adjacent healthy cells. Much attention has been focused on the liposomal drug delivery system (DDS) as an attractive, intelligent technology of targeting and controlled release of (10)B compounds. Two approaches have been investigated for incorporation of (10)B into liposomes: (1) encapsulation of (10)B compounds into liposomes and (2) incorporation of (10)B-conjugated lipids into the liposomal bilayer. Our laboratory has developed boron ion cluster lipids for application of the latter approach. In this chapter, our boron lipid liposome approaches as well as recent developments of the liposomal boron delivery system are summarized. PMID:19913168

Nakamura, Hiroyuki

2009-01-01

348

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

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

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

2007-01-01

349

Ultrahard nanotwinned cubic boron nitride.  

PubMed

Cubic boron nitride (cBN) is a well known superhard material that has a wide range of industrial applications. Nanostructuring of cBN is an effective way to improve its hardness by virtue of the Hall-Petch effect--the tendency for hardness to increase with decreasing grain size. Polycrystalline cBN materials are often synthesized by using the martensitic transformation of a graphite-like BN precursor, in which high pressures and temperatures lead to puckering of the BN layers. Such approaches have led to synthetic polycrystalline cBN having grain sizes as small as ?14?nm (refs 1, 2, 4, 5). Here we report the formation of cBN with a nanostructure dominated by fine twin domains of average thickness ?3.8?nm. This nanotwinned cBN was synthesized from specially prepared BN precursor nanoparticles possessing onion-like nested structures with intrinsically puckered BN layers and numerous stacking faults. The resulting nanotwinned cBN bulk samples are optically transparent with a striking combination of physical properties: an extremely high Vickers hardness (exceeding 100?GPa, the optimal hardness of synthetic diamond), a high oxidization temperature (?1,294?°C) and a large fracture toughness (>12?MPa?m(1/2), well beyond the toughness of commercial cemented tungsten carbide, ?10?MPa?m(1/2)). We show that hardening of cBN is continuous with decreasing twin thickness down to the smallest sizes investigated, contrasting with the expected reverse Hall-Petch effect below a critical grain size or the twin thickness of ?10-15?nm found in metals and alloys. PMID:23325219

Tian, Yongjun; Xu, Bo; Yu, Dongli; Ma, Yanming; Wang, Yanbin; Jiang, Yingbing; Hu, Wentao; Tang, Chengchun; Gao, Yufei; Luo, Kun; Zhao, Zhisheng; Wang, Li-Min; Wen, Bin; He, Julong; Liu, Zhongyuan

2013-01-17

350

Boron nitride nanotubes for spintronics.  

PubMed

With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics. PMID:25248070

Dhungana, Kamal B; Pati, Ranjit

2014-01-01

351

Boron Nitride Nanotubes for Spintronics  

PubMed Central

With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics. PMID:25248070

Dhungana, Kamal B.; Pati, Ranjit

2014-01-01

352

Unexpected Reconstruction of the ?-Boron (111) Surface.  

PubMed

We report a novel reconstruction of the ?-boron (111) surface, discovered using ab initio evolutionary structure prediction, and show that this unexpected neat structure has a much lower energy than the recently proposed (111)-I_{R,(a)} surface. In this reconstruction, all single interstitial boron atoms bridge neighboring B_{12} icosahedra by polar covalent bonds, and this satisfies the electron counting rule, leading to the reconstruction-induced metal-semiconductor transition. The peculiar charge transfer between the interstitial atoms and the icosahedra plays an important role in stabilizing the surface. PMID:25379924

Zhou, Xiang-Feng; Oganov, Artem R; Shao, Xi; Zhu, Qiang; Wang, Hui-Tian

2014-10-24

353

Thermal conductivity behavior of boron carbides  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

354

Rare earth-iron-boron-permanent magnets  

SciTech Connect

This patent describes a neodymium-iron-boron permanent magnet containing added rare earth oxide. It is prepared by the method of comprising the steps of: mixing together components: a particulate alloy consisting essentially of neodymium, iron, cobalt, and boron; and a particulate rare earth oxide selected from the group consisting of gadolinium oxide, terbium oxide, dysprosium oxide, holmium oxide, and mixtures thereof; aligning magnetic domains of the mixture in a magnetic field; compacting the aligned mixture to form a shape; sintering the compacted shape; and annealing the sintered shape.

Ghandehari, M.H.

1990-08-28

355

Synthesis and characterization of boron carbide nanoparticles  

NASA Astrophysics Data System (ADS)

Boron carbide nanoparticles were made via a reaction of boron, obtained from thermal decomposition of magnesium diboride, with multiwall carbon nanotubes at 1150 °C for 3 h in vacuum. The size of the nanoparticles is smaller than 100 nm. The bamboo structure of the multiwall carbon nanotubes is the key to the successful synthesis of such nanoparticles. Good crystallinity was demonstrated by scanning electron microscope images and X-ray diffraction patterns. The single-crystal nature of each nanoparticle was evidenced by a high-resolution lattice image obtained using a transmission electron microscope.

Chen, S.; Wang, D. Z.; Huang, J. Y.; Ren, Z. F.

356

Nuclear fusion of protons with boron  

SciTech Connect

Two methods are investigated in this paper to convert the released fusion energy directly in electric power. The first is very simply the use of a beam of protons traversing a fixed target of Boron. Unfortunately this method cannot be made to work, but its investigation naturally yields to the second method which makes use of two beams, one of protons and one of ions of Boron, colliding with each other. This second method is feasible but it requires a significant amount of research and development in accelerator technology.

Ruggiero, A.G.

1992-09-01

357

Unexpected Reconstruction of the ?-Boron (111) Surface  

NASA Astrophysics Data System (ADS)

We report a novel reconstruction of the ?-boron (111) surface, discovered using ab initio evolutionary structure prediction, and show that this unexpected neat structure has a much lower energy than the recently proposed (111)-IR ,(a) surface. In this reconstruction, all single interstitial boron atoms bridge neighboring B12 icosahedra by polar covalent bonds, and this satisfies the electron counting rule, leading to the reconstruction-induced metal-semiconductor transition. The peculiar charge transfer between the interstitial atoms and the icosahedra plays an important role in stabilizing the surface.

Zhou, Xiang-Feng; Oganov, Artem R.; Shao, Xi; Zhu, Qiang; Wang, Hui-Tian

2014-10-01

358

Boron aluminum crippling strength shows improvement  

NASA Technical Reports Server (NTRS)

Results are presented from an experimental program directed toward improving boron aluminum crippling strength. Laminate changes evaluated were larger filament diameter, improved processing, shape changes, adding steel-aluminum cross plies, reduced filament volume in corners, adding boron aluminum angle plies, and using titanium interleaves. Filament diameter and steel-aluminum cross plies have little effect on crippling. It is shown that better processing combined with appropriate shape changes improved crippling over 50 percent at both room temperature and 600 F. Tests also show that crippling improvements ranging from 20 to 40 percent are achieved using angle plies and titanium interleaves.

Otto, O. R.; Bohlmann, R. E.

1974-01-01

359

Low pressure growth of cubic boron nitride films  

NASA Technical Reports Server (NTRS)

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.

Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

1997-01-01

360

Lithium-Beryllium-Boron and Oxygen in the early Galaxy  

E-print Network

Oxygen is a much better evolutionary index than iron to follow the history of Lithium-Beryllium-Boron (LiBeB) since it is the main producer of these light elements at least in the early Galaxy. The O-Fe relation is crucial to the determination of the exact physical process responsible for the LiBeB production. Calculated nucleosynthetic yields of massive stars, estimates of the energy cost of Be production, and above all recent observations reported in this meeting seem to favor a mechanism in which fast nuclei enriched into He, C and O arising from supernovae are accelerated in superbubbles and fragment on H and He in the interstellar medium.

Elisabeth Vangioni-Flam; Michel Casse

2000-11-24

361

Electron-beam processing of kilogram quantities of iridium for radioisotope thermoelectric generator applications  

SciTech Connect

Iridium alloys are used as fuel-cladding materials in radioisotope thermoelectric generators (RTGs). Hardware produced at the Oak Ridge National Laboratory (ORNL) has been used in Voyagers I and 2, Galilee, and Ulysses spacecraft. An integral part of the production of iridium-sheet metal involves electron-beam (EB) processing. These processes include the degassing of powder-pressed compacts followed by multiple meltings in order to purify 500-g buttons of Ir-0.3% W alloy. Starting in 1972 and continuing into 1992, our laboratory EB processing was Performed (ca. 1970) in a 60-kW (20 kV at 3 A), two-gun system. In 1991, a new 150-kW EB gun facility was installed to complement the older unit. This paper describes how the newly installed system was qualified for production of RTG developmental work is discussed that will potentially improve the existing process by utilizing the capabilities of the new EB system.

Huxford, T.J.; Ohriner, E.K.

1992-01-01

362

Electron-beam processing of kilogram quantities of iridium for radioisotope thermoelectric generator applications  

SciTech Connect

Iridium alloys are used as fuel-cladding materials in radioisotope thermoelectric generators (RTGs). Hardware produced at the Oak Ridge National Laboratory (ORNL) has been used in Voyagers I and 2, Galilee, and Ulysses spacecraft. An integral part of the production of iridium-sheet metal involves electron-beam (EB) processing. These processes include the degassing of powder-pressed compacts followed by multiple meltings in order to purify 500-g buttons of Ir-0.3% W alloy. Starting in 1972 and continuing into 1992, our laboratory EB processing was Performed (ca. 1970) in a 60-kW (20 kV at 3 A), two-gun system. In 1991, a new 150-kW EB gun facility was installed to complement the older unit. This paper describes how the newly installed system was qualified for production of RTG developmental work is discussed that will potentially improve the existing process by utilizing the capabilities of the new EB system.

Huxford, T.J.; Ohriner, E.K.

1992-12-31

363

Boron isotope fractionation in liquid chromatography with boron-specific resins as column packing material  

SciTech Connect

Boron-specific resins with n-methyl glucamine as the functional group were used as column packing material of liquid chromatography for boron isotope separation. The shapes of chromatograms in reverse breakthrough experiments were heavily dependent on the pH of the eluents, and there existed a pH value at which a chromatogram of the displacement type was realized nearly ideally. The value of the single-stage separation factor for the boron isotopes varied between 1.010 and 1.022, depending on the temperature and the form of the resins. The existence of the three-coordinate boron species in addition to the four-coordinate species in the resin phase is suggested.

Oi, Takao; Shimazaki, Hiromi; Ishii, Reiko [Sophia Univ., Tokyo (Japan); Hosoe, Morikazu [National Defense Academy, Kanagawa (Japan)

1997-07-01

364

Elongation of planar boron clusters by hydrogenation: boron analogues of polyenes.  

PubMed

Dihydrogenated boron clusters, H(2)B(n)(-) (n = 7-12), were produced and characterized using photoelectron spectroscopy and computational chemistry to have ladderlike structures terminated by a hydrogen atom on each end. The two rows of boron atoms in the dihydrides are bonded by delocalized three-, four-, or five-center ? and ? bonds. The ? bonding patterns in these boron nanoladders bear similarities to those in conjugated alkenes: H(2)B(7)(-), H(2)B(8), and H(2)B(9)(-), each with two ? bonds, are similar to butadiene, while H(2)B(10)(2-), H(2)B(11)(-), and H(2)B(12), each with three ? bonds, are analogous to 1,3,5-hexatriene. The boron cluster dihydrides can thus be considered as polyene analogues, or "polyboroenes". Long polyboroenes with conjugated ? bonds (analogous to polyacetylenes), which may form a new class of molecular wires, should exist. PMID:22849590

Li, Wei-Li; Romanescu, Constantin; Jian, Tian; Wang, Lai-Sheng

2012-08-15

365

Possible Precursors for Boron Nanotubes: A Novel Bonding Picture in Boron Sheets and Nanotubes  

NASA Astrophysics Data System (ADS)

Boron nanotubes (BNTs) have attracted a great deal of attention due to their unique properties: unlike carbon nanotubes (CNTs), all BNTs are predicted to be metallic regardless of chirality or radii. Based on density functional theory, we present a class of boron sheets, composed of mixtures of triangular and hexagonal motifs, that are more stable than any sheet-structures considered to date and thus are more likely to be the precursors of atomically thin BNTs [1]. We describe a picture of the nature of the bonding in these sheets which clarifies their stability. We further point out that our bonding picture, which focuses on the balance of two-center and three-center bonding, is crucial for the stability of other boron nanostructures. We also discuss BNTs made from our new boron sheets. [1] H. Tang and S. Ismail-Beigi, Phys. Rev. Lett. 99, 115501 (2007).

Tang, Hui; Ismail-Beigi, Sohrab

2008-03-01

366

Essentiality of boron for healthy bones and joints.  

PubMed Central

Since 1963, evidence has accumulated that suggests boron is a safe and effective treatment for some forms of arthritis. The initial evidence was that boron supplementation alleviated arthritic pain and discomfort of the author. This was followed by findings from numerous other observations epidemiologic and controlled animal and human experiments. These findings included a) analytical evidence of lower boron concentrations in femur heads, bones, and synovial fluid from people with arthritis than from those without this disorder; b) observation evidence that bones of patients using boron supplements are much harder to cut than those of patients not using supplements; c) epidemiologic evidence that in areas of the world where boron intakes usually are 1.0 mg or less/day the estimated incidence of arthritis ranges from 20 to 70%, whereas in areas of the world where boron intakes are usually 3 to 10 mg, the estimated incidence of arthritis ranges from 0 to 10%; d) experimental evidence that rats with induced arthritis benefit from orally or intraperitoneally administered boron; e) experimental evidence from a double-blind placebo-boron supplementation trial with 20 subjects with osteoarthritis. A significant favorable response to a 6 mg boron/day supplement was obtained; 50% of subjects receiving the supplement improved compared to only 10% receiving the placebo. The preceding data indicate that boron is an essential nutrient for healthy bones and joints, and that further research into the use of boron for the treatment or prevention of arthritis is warranted. PMID:7889887

Newnham, R E

1994-01-01

367

Microstructure and electrochemical properties of boron-doped mesocarbon microbeads  

SciTech Connect

The microstructure and electrochemical properties of pristine and boron-doped mesocarbon microbeads (MCMBs) were comparatively studied by X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and electrochemical measurements. The authors examined the correlation between the boron-doping effect and the electrochemical properties of boron-doped MCMBs prepared at different heat-treatment temperatures. It was found that boron doping in MCMBs starts above 1,800 C, and then the substitution reaction proceeds with increasing heat-treatment temperature. The effect of boron doping is to accelerate graphitization of MCMBs for heat-treatment temperatures in the range from 1,800 to 2,500 C. Electrochemical lithium intercalation takes place at a higher potential in boron-doped MCMBs than in undoped MCMBs, presumably because the substitutional boron acts as an electron acceptor in the MCMBs.

Kim, C.; Fujino, T.; Miyashita, K.; Hayashi, T.; Endo, M.; Dresselhaus, M.S.

2000-04-01

368

Process of Making Boron-Fiber Reinforced Composite Tape  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

369

Boron carbide as a target for the SPES project  

NASA Astrophysics Data System (ADS)

Within the framework of the research on targets for the SPES project (Selective Production of Exotic Species), porous boron carbide (B4C) based materials were produced from the carbothermal reduction of boric acid and two different carbon sources, i.e. citric acid and phenolic resin. Samples composition and microstructural morphology were studied by means of X-ray diffraction spectrometry (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The amount of total porosity was obtained from the comparison between the theoretical density and the measured bulk density. To better characterize the material microstructure, nitrogen physisorption measurements were performed in order to obtain data about the type of generated porosity and the specific surface area of the samples. Analysis performed on the samples show that after the final thermal treatment they are composed of boron carbide and residual free carbon, whose quantity is related to the processes involved in the two synthesis. Remarkable differences in the overall weight loss have been noticed for the two different reactions, resulting in different densities and pore size distributions, but in both cases similar values of specific surface area (SSA) were obtained.

Corradetti, S.; Carturan, S.; Biasetto, L.; Andrighetto, A.; Colombo, P.

2013-01-01

370

Boron-containing organic pigments from a Jurassic red alga  

PubMed Central

Organic biomolecules that have retained their basic chemical structures over geological periods (molecular fossils) occur in a wide range of geological samples and provide valuable paleobiological, paleoenvironmental, and geochemical information not attainable from other sources. In rare cases, such compounds are even preserved with their specific functional groups and still occur within the organisms that produced them, providing direct information on the biochemical inventory of extinct organisms and their possible evolutionary relationships. Here we report the discovery of an exceptional group of boron-containing compounds, the borolithochromes, causing the distinct pink coloration of well-preserved specimens of the Jurassic red alga Solenopora jurassica. The borolithochromes are characterized as complicated spiroborates (boric acid esters) with two phenolic moieties as boron ligands, representing a unique class of fossil organic pigments. The chiroptical properties of the pigments unequivocally demonstrate a biogenic origin, at least of their ligands. However, although the borolithochromes originated from a fossil red alga, no analogy with hitherto known present-day red algal pigments was found. The occurrence of the borolithochromes or their possible diagenetic products in the fossil record may provide additional information on the classification and phylogeny of fossil calcareous algae. PMID:20974956

Wolkenstein, Klaus; Gross, Jurgen H.; Falk, Heinz

2010-01-01

371

Boron deficiency in cotton in calcareous soils of Pakistan. II. correction and internal boron requirement  

Microsoft Academic Search

On the revelation of widespread boron (B) deficiency in cotton (Gossypium hirsutum L.), 26 replicated farmers' field experiments were conducted over 4 years in soils with <0.6 mg HWE B kg-1. Boron was supplied either through soil surface broadcast or foliar feeding. Soil application rates ranged from 0-3 kg B ha-1 as borax and foliar feeding was done by three

372

Boron uptake measurements in a rat model for Boron Neutron Capture Therapy of lung tumours.  

PubMed

Lung carcinoma is the leading cause of cancer mortality in the Western countries. Despite the introduction over the last few years of new therapeutic agents, survival from lung cancer has shown no discernible improvement in the last 20 years. For these reasons any efforts to find and validate new effective therapeutic procedures for lung cancer are very timely. The selective boron uptake in the tumour with respect to healthy tissues makes Boron Neutron Capture Therapy a potentially advantageous option in the treatment of tumours that affect whole vital organs, and that are surgically inoperable. To study the possibility of applying BNCT to the treatment of diffuse pulmonary tumours, an animal model for boron uptake measurements in lung metastases was developed. Both healthy and tumour-bearing rats were infused with Boronophenylalanine (BPA) and sacrificed at different time intervals after drug administration. The lungs were extracted, and prepared for boron analysis by neutron autoradiography and ?-spectroscopy. The boron concentrations in tumour and normal lung were plotted as a function of the time elapsed after BPA administration. The concentration in tumour is almost constant within the error bars for all the time intervals of the experiment (1-8 h), while the curve in normal lung decreases after 4 h from BPA infusion. At 4 h, the ratio of boron concentration in tumour to boron concentration in healthy lung is higher than 3, and it stays above this level up to 8 h. Also the images of boron distribution in the samples, obtained by neutron autoradiography, show a selective absorption in the metastases. PMID:21145752

Bortolussi, S; Bakeine, J G; Ballarini, F; Bruschi, P; Gadan, M A; Protti, N; Stella, S; Clerici, A; Ferrari, C; Cansolino, L; Zonta, C; Zonta, A; Nano, R; Altieri, S

2011-02-01

373

Novel precursors for boron nanotubes: the competition of two-center and three-center bonding in boron sheets.  

PubMed

We present a new class of boron sheets, composed of triangular and hexagonal motifs, that are more stable than structures considered to date and thus are likely to be the precursors of boron nanotubes. We describe a simple and clear picture of electronic bonding in boron sheets and highlight the importance of three-center bonding and its competition with two-center bonding, which can also explain the stability of recently discovered boron fullerenes. Our findings call for reconsideration of the literature on boron sheets, nanotubes, and clusters. PMID:17930448

Tang, Hui; Ismail-Beigi, Sohrab

2007-09-14

374

Drinking water health advisory for boron  

Microsoft Academic Search

The Health Advisory Program, sponsored by the Environmental Protection Agency's Office of Water, has issued its report on the element boron: included are the compounds boric acid and borax(sodium tetraborate). It provides information on the health effects, analytical methodology, and treatment technology that would be useful in dealing with the contamination of drinking water. Health Advisories (HAs) describe nonregulatory concentrations

Cantilli

1991-01-01

375

Boron-doped manganese dioxide for supercapacitors.  

PubMed

The addition of boron as a dopant during the reaction between carbon fiber and permanganate led to significant enhancement of the growth-rate and formation of the porous framework. The doped MnO2 was superior to the pristine sample as electrode materials for supercapacitors in terms of the specific capacitance and rate capability. PMID:25232909

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

2014-11-11

376

Tetrahedral boron in naturally occurring tourmaline  

SciTech Connect

Evidence for boron in both trigonal and tetrahedral coordination has been found in {sup 11}B magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectra of natural, inclusion-free specimens of aluminum-rich lithian tourmaline from granitic pregmatites.

Tagg, S.L.; Cho, H. [Pacific Northwest National Lab., Richland, WA (United States). Environmental Molecular Sciences Lab.; Dyar, M.D. [Mount Holyoke Coll., South Hadley, MA (United States). Dept. of Geology and Geography; Grew, E.S. [Univ. of Maine, Orono, ME (United States). Dept. of Geological Sciences

1999-09-01

377

NEW ADVANCES IN BORON SOIL CHEMISTRY - Paper  

EPA Science Inventory

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

378

Boron reduces development of clubroot in canola  

Microsoft Academic Search

Boron (B) slows the development of Plasmodiophora brassicae (clubroot) during infection of root hairs (primary infection) and the root cortex (secondary infection) of several vegetable Brassica spp., but the impact of B application on clubroot development in canola has not been assessed. The present study assessed the impact of B application rates (0, 0.25, 0.5, 1, 2, 4, 8, 16,

A. Deora; B. D. Gossen; F. Walley; M. R. McDonald

2011-01-01

379

Novel Boron Based Multilayer Thermal Neutron Detector  

E-print Network

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

SCHIEBER, M

2010-01-01

380

Novel Boron Based Multilayer Thermal Neutron Detector  

E-print Network

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

M. SCHIEBER; O. KHAKHAN

2010-06-09

381

Axial residual stresses in boron fibers  

NASA Technical Reports Server (NTRS)

The axial residual stress distribution as a function of radius was determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diameter fibers were similar, being compressive at the surface and changing monotonically to a region of tensile within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile stress of about 860 mn/sq.m and then decreases to a compressive stress near the tungsten boride core. Data were presented for 203 micron diameter B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102 micron diameter B/W and boron on carbon (b/C) shows that the residual stresses were similar in the outer regions of the fibers, but that large differences near and in the core were observed. The effects of these residual stresses on the fracture of boron fibers were discussed.

Behrendt, D. R.

1978-01-01

382

Crystalline Boron Nanoribbons: Synthesis and Characterization  

E-print Network

, Illinois 60612 Received January 20, 2004; Revised Manuscript Received March 3, 2004 ABSTRACT Catalyst vapor transport method using boron and iodine as precursor,12,13 and also by laser ablation of a BB as catalyst,18 post- annealing of amorphous B NWs at high temperature (1050 °C),19 and pyrolysis of B2H6

383

In vitro and in vivo studies of boron neutron capture therapy: boron uptake/washout and cell death.  

PubMed

Boron neutron capture therapy (BNCT) is a binary radiotherapy based on thermal-neutron irradiation of cells enriched with (10)B, which produces ? particles and (7)Li ions of short range and high biological effectiveness. The selective uptake of boron by tumor cells is a crucial issue for BNCT, and studies of boron uptake and washout associated with cell survival studies can be of great help in developing clinical applications. In this work, boron uptake and washout were characterized both in vitro for the DHDK12TRb (DHD) rat colon carcinoma cell line and in vivo using rats bearing liver metastases from DHD cells. Despite a remarkable uptake, a large boron release was observed after removal of the boron-enriched medium from in vitro cell cultures. However, analysis of boron washout after rat liver perfusion in vivo did not show a significant boron release, suggesting that organ perfusion does not limit the therapeutic effectiveness of the treatment. The survival of boron-loaded cells exposed to thermal neutrons was also assessed; the results indicated that the removal of extracellular boron does not limit treatment effectiveness if adequate amounts of boron are delivered and if the cells are kept at low temperature. Cell survival was also investigated theoretically using a mechanistic model/Monte Carlo code originally developed for radiation-induced chromosome aberrations and extended here to cell death; good agreement between simulation outcomes and experimental data was obtained. PMID:21133762

Ferrari, C; Bakeine, J; Ballarini, F; Boninella, A; Bortolussi, S; Bruschi, P; Cansolino, L; Clerici, A M; Coppola, A; Di Liberto, R; Dionigi, P; Protti, N; Stella, S; Zonta, A; Zonta, C; Altieri, S

2011-04-01

384

Palladium-catalyzed, direct boronic acid synthesis from aryl chlorides: a simplified route to diverse boronate ester derivatives.  

PubMed

Although much current research focuses on developing new boron reagents and identifying robust catalytic systems for the cross-coupling of these reagents, the fundamental preparations of the nucleophilic partners (i.e., boronic acids and derivatives) has been studied to a lesser extent. Most current methods to access boronic acids are indirect and require harsh conditions or expensive reagents. A simple and efficient palladium-catalyzed, direct synthesis of arylboronic acids from the corresponding aryl chlorides using an underutilized reagent, tetrahydroxydiboron B(2)(OH)(4), is reported. To ensure preservation of the carbon-boron bond, the boronic acids were efficiently converted to the trifluoroborate derivatives in good to excellent yields without the use of a workup or isolation. Further, the intermediate boronic acids can be easily converted to a wide range of useful boronates. Finally, a two-step, one-pot method was developed to couple two aryl chlorides efficiently in a Suzuki-Miyaura-type reaction. PMID:21105666

Molander, Gary A; Trice, Sarah L J; Dreher, Spencer D

2010-12-22

385

Substitution reactions at tetracoordinate boron: synthesis of N-heterocyclic carbene boranes with boron-heteroatom bonds.  

PubMed

Boryl halide, carboxylate and sulfonate complexes of 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (dipp-Imd-BH(2)X, X = halide or sulfonate) have been prepared from the parent borane dipp-Imd-BH(3) by (1) substitution reactions with R-X (X = halide or sulfonate), (2) reactions with electrophiles (like I(2) or NIS), or (3) acid/base reactions with HX (provided that HX has a pK(a) of about 2 or less). Dipp-Imd-BH(2)I is most conveniently prepared by reaction with diiodine while dipp-Imd-BH(2)OTf is best prepared by reaction with triflic acid. These and other less reactive complexes behave as electrophiles and can be substituted by a wide range of heteroatom nucleophiles including halides, thiolates and other sulfur-based nucleophiles, isocyanate, azide, nitrite, and cyanide. The resulting products are remarkably stable, and many have been characterized by X-ray crystallography. Several are members of very rare classes of functionalized boron compounds (boron azide, nitro compound, nitrous ester, etc.). PMID:20886852

Solovyev, Andrey; Chu, Qianli; Geib, Steven J; Fensterbank, Louis; Malacria, Max; Lacôte, Emmanuel; Curran, Dennis P

2010-10-27

386

Kuiper Belt Object Orbiter using Advanced Radioisotope Power Sources and Electric Propulsion  

NASA Astrophysics Data System (ADS)

A joint NASA GRC/JPL design study was performed for the NASA Radioisotope Power Systems Office to explore the use of radioisotope electric propulsion for flagship class missions. The Kuiper Belt Object Orbiter is a flagship class mission concept projected for launch in the 2030 timeframe. Due to the large size of a flagship class science mission larger radioisotope power system `building blocks' were conceptualized to provide the roughly 4 kW of power needed by the NEXT ion propulsion system and the spacecraft. Using REP the spacecraft is able to rendezvous with and orbit a Kuiper Belt object in 16 years using either eleven (no spare) 420 W advanced RTGs or nine (with a spare) 550 W advanced Stirling Radioisotope systems. The design study evaluated integrating either system and estimated impacts on cost as well as required General Purpose Heat Source requirements.

Oleson, S. R.; McGuire, M. L.; Dankanich, J.; Colozza, A.; Schmitz, P.; Khan, O.; Drexler, J.; Fittje, J.

387

Enabling Decadal Survey Science Goals for Primitive Bodies Using Radioisotope Electric Propulsion  

NASA Astrophysics Data System (ADS)

We show how Radioisotope-Electric Propulsion (REP) spacecraft could orbit one or more Trojan asteroids with reasonable trip times and payloads, enabling many of the Decadal Survey primitive bodies' science goals, within a New Frontiers-scale budget.

Prockter, L. M.; Rivkin, A. S.; McNutt, R. L., Jr.; Gold, R. E.; Ostdiek, P. H.; Leary, J. C.; Fiehler, D. I.; Oleson, S. R.; Witzberger, K. E.

2006-03-01

388

Galileo light-weight radioisotope heater units design and safety analysis  

SciTech Connect

The Light-Weight Radioisotope Heater Unit (LWRHU) provides thermal energy to temperature sensitive components aboard the orbiter/probe of the Galileo Spacecraft during its multiyear interplanetary mission. Heat is derived from the radioisotopic decay of 238-plutonium. A power of 0.56 watts/gram of radioisotope, a half-life of 88 years, and no moving parts permitted a robust, long-lived, compact heat source design. A single l-w design provided small thermal increments, with options in the number and placement, to satisfy the needed thermal environment for the spacecraft components. Radioisotope use in these devices necessitated the assessment of postulated radiological risks in accidents or malfunctions of the space shuttle or the Galileo spacecraft during near earth mission phases. Included in this document are data for the design, postulated accidents with their consequences, test data, and the derived source terms and personnel exposures for the various events. 5 refs., 1 fig., 1 tab.

Johnson, E.W. (EG and G Mound Applied Technologies, Miamisburg, OH (USA)); Zocher, R.W. (Los Alamos National Lab., NM (USA))

1990-01-01

389

Radioisotope Electric Propulsion (REP): A Near-Term Approach to Nuclear Propulsion  

NASA Technical Reports Server (NTRS)

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

Schmidt, George R.; Manzella, David H.; Kamhawi, Hani; Kremic, Tibor; Oleson, Steven R.; Dankanich, John W.; Dudzinski, Leonard A.

2009-01-01

390

Boron carbide nanowires: Synthesis and characterization  

NASA Astrophysics Data System (ADS)

Bulk boron carbide has been widely used in ballistic armored vest and the property characterization has been heavily focused on mechanical properties. Even though boron carbides have also been projected as a promising class of high temperature thermoelectric materials for energy harvesting, the research has been limited in this field. Since the thermal conductivity of bulk boron carbide is still relatively high, there is a great opportunity to take advantage of the nano effect to further reduce it for better thermoelectric performance. This dissertation work aims to explore whether improved thermoelectric performance can be found in boron carbide nanowires compared with their bulk counterparts. This dissertation work consists of four main parts. (1) Synthesis of boron carbide nanowires. Boron carbide nanowires were synthesized by co-pyrolysis of diborane and methane at low temperatures (with 879 °C as the lowest) in a home-built low pressure chemical vapor deposition (LPCVD) system. The CVD-based method is energy efficient and cost effective. The as-synthesized nanowires were characterized by electron microscopy extensively. The transmission electron microscopy (TEM) results show the nanowires are single crystalline with planar defects. Depending on the geometrical relationship between the preferred growth direction of the nanowire and the orientation of the defects, the as-synthesized nanowires could be further divided into two categories: transverse fault (TF) nanowires grow normal to the defect plane, while axial fault (AF) ones grow within the defect plane. (2) Understanding the growth mechanism of as-synthesized boron carbide nanowires. The growth mechanism can be generally considered as the famous vapor-liquid-solid (VLS) mechanism. TF and AF nanowires were found to be guided by Ni-B catalysts of two phases. A TF nanowire is lead by a hexagonal phase catalyst, which was proved to be in a liquid state during reaction. While an AF nanowires is catalyzed by a solid orthorhombic phase catalyst. The status of a catalyst depends mainly on temperature. (3) Observation of "invisible" defects in boron carbide nanowires. The planar defects can only be seen under a transmission electron microscope when the electron beam is within the defect plane. Furthermore, there are only two directions within that plane, along which the orientation of defect can be told and clear TEM results can be taken. The challenge is that the TEM sample holder is limited to tilt +/-30° in each direction. A theory was developed based on lattice calculation and simulation to tell the orientation of defect even not from those unique directions. Furthermore, it was tested by experimental data and proved to be successful. (4) Preliminary exploration of structure-transport property of as-synthesized boron carbide nanowires. In collaboration with experts in the field of thermal science, thermal transport properties of a few boron carbide nanowires were studied. All measured nanowires were either pre-characterized or post-characterized by TEM to reveal their structural information such as diameter, fault orientations and chemical composition. The obtained structural information was then analyzed together with measured thermal conductivity to establish a structure-transport property relation. Current data indicate that TF ones have a lower thermal conductivity, which is also diameter-dependent.

Guan, Zhe

391

The effects of boron neutron capture irradiation on oral mucosa: evaluation using a rat tongue model.  

PubMed

The ventral surface of the tongue of male Fisher 344 rats was used to evaluate the response of oral mucosa to boron neutron capture irradiation. Three hours after i.p. injection of 700 mg/kg of the boron delivery agent p-boronophenylalanine (BPA), the boron concentrations in blood and tongue mucosal epithelium were approximately 21 and 23 microgram (10)B/g, respectively. The doses required to produce a 50% incidence of ulceration with X rays, the Brookhaven Medical Research Reactor thermal neutron beam alone, or the thermal neutron beam in the presence of BPA were 13.4 +/- 0.2, 4. 2 +/- 0.1, and 3.0 +/- 0.1 Gy, respectively. Ulceration of the tongue was evident by 6 to 7 days after irradiation, irrespective of the irradiation modality; healing was related to dose and was relatively rapid (products of the boron neutron capture reaction, (10)B(n,alpha)(7)Li. Oral mucosa is highly sensitive to BPA-mediated BNC irradiation and could be a dose-limiting normal tissue in BNCT of brain tumors, or if BPA-based BNCT is applied to the treatment of head and neck tumors. PMID:10409319

Coderre, J A; Morris, G M; Kalef-Ezra, J; Micca, P L; Ma, R; Youngs, K; Gordon, C R

1999-08-01

392

Role of grain size in superconducting boron-doped nanocrystalline diamond thin films grown by CVD  

NASA Astrophysics Data System (ADS)

The grain size dependence of the superconducting transition, the normal state resistivity, and the insulating behavior at high magnetic fields are studied on a series of boron-doped nanocrystalline diamond (B:NCD) thin films with different grain sizes. The systematic change of the grain size is achieved by varying the methane-to-hydrogen ratio (C/H ratio) for the growth of different B:NCD films. Even though a fixed trimethylboron- (TMB) to-methane gas ratio is supposed to induce the identical boron-doping level in all the B:NCD films, the boron concentration and the carrier density are found to be a decreasing function of the grain size. Another consequence of the increase in grain size is the decreasing grain boundary density. These two concurrent consequences of the chemical vapor deposition mode of B:NCD are responsible for the grain size dependence of the critical temperature TC, the localization radius aH at the boron site, the normal state resistivity ?norm, the Hall mobility ?H, the Ioffe-Regel product kFl, the HC2-T phase boundary, and the coherence length ?GL.

Zhang, Gufei; Janssens, S. D.; Vanacken, J.; Timmermans, M.; Vacík, J.; Ataklti, G. W.; Decelle, W.; Gillijns, W.; Goderis, B.; Haenen, K.; Wagner, P.; Moshchalkov, V. V.

2011-12-01

393

Analysis of boronic acids by nano liquid chromatography-direct electron ionization mass spectrometry.  

PubMed

A new method, based on a direct-electron ionization (EI) interface, is presented for the analysis of compounds insufficiently amenable to usual MS methods. The instrumentation is composed of a nano liquid chromatograph (LC) and a mass spectrometer (MS) directly coupled by a transfer capillary. The eluent is directly introduced into the heated electron impact ion source of the MS. Significant advantages are the generation of reproducible spectra and the ability to ionize highly polar compounds. Boronic acids are used as coupling reagents to produce drugs, agrochemicals, or herbicides. The purity of educts is of high importance because impurities in the educt are directly associated with impurities in the product. Because of their high polarity and tendency to form boroxines, boronic acids require derivatization for GC analysis. The presented nano-LC-EI/MS method is easily applicable for a broad range of boronic acids. The method shows good detection limits for boronic acids up to 200 pg, is perfectly linear, and shows a very high robustness and reproducibility. A mixture of compounds could easily be separated on a monolithic RP18e column. The method represents a new, simple, robust, and reproducible approach for the detection of polar analytes. It is a good candidate to become a standard method for industrial applications. PMID:20411924

Flender, Cornelia; Leonhard, Peter; Wolf, Christian; Fritzsche, Matthias; Karas, Michael

2010-05-15

394

Research on wear characteristics of AISI 1035 steel boronized at various parameters  

Microsoft Academic Search

Purpose – This paper aims to research the tribological features of AISI 1035 steel, boronized at various parameters. Design\\/methodology\\/approach – The samples were boronized via box boronizing method. By using Ekabor 2 powders, boronizing was conducted at 840, 880, 920, 960 and 1,000°C for two, four and six hours. Wear resistance of boronized samples at determined parameters were analysed. Wear

N. Kiratli; F. Findik

2011-01-01

395

The effect of boron incorporation on the structure and properties of glassy carbon  

Microsoft Academic Search

Boron was introduced into glassy carbon by chemical modification and by irradiating the precursor polymer with boron ions. Using chemical modification, a polymer with uniform distribution of boron in the bulk was obtained, whereas irradiation with B3+ produced a polymer with boron located in a narrow region under the surface. Following modification with boron, the samples were carbonized at 1273K

Ana Kalijadis; Zoran Jovanovi?; Mila Lauševi?; Zoran Lauševi?

2011-01-01

396

High efficiency beta radioisotope energy conversion using reciprocating electromechanical converters with integrated betavoltaics  

Microsoft Academic Search

We demonstrate a 5.1% energy conversion efficiency 63Ni radioisotope power generator by integrating silicon betavoltaic converters with radioisotope actuated reciprocating piezoelectric unimorph cantilever converters. The electromechanical energy converter efficiently utilizes both the kinetic energy and the electrical charge of the 0.94 muW beta radiation from a 9 mCi 63Ni thin film source to generate maximum (1) continuous betavoltaic electrical power

Rajesh Duggirala; Hui Li; Amit Lal

2008-01-01

397

A technique to measure heats of reaction of titanium-boron, aluminim-titanium-boron, and aluminum-titanium-boron-carbon powder blends  

NASA Astrophysics Data System (ADS)

In this research, a modification to initiation aid ignition in bomb calorimetry that involves systemically blending levels of boron and potassium nitrate initiation aids with a bulk structural energetic elemental power blend is developed. A regression is used to estimate the nominal heat of reaction for the primary reaction. The technique is first applied to the synthesis of TiB 2 as a validation study to see if close proximity to literature values can be achieved. The technique is then applied to two systems of interest, Al-Ti-B, and Al-Ti-B4C. In all three investigations, x-ray diffraction is used to characterize the product phases of the reactions to determine the extent and identity of the product phases and any by-products that may have formed as a result of adding the initiation aid. The experimental data indicates the technique approximates the heat of reaction value for the synthesis of TiB2 from Ti-B powder blends and the formation of TiB2 is supported by volume fraction analysis by x-ray diffraction. Application to the Al-Ti-B and Al-Ti-B4C blends show some correlation with variation of the initiation aid, with x-ray diffraction showing the formation of equilibrium products. However, these blends require further investigation to resolve more complex interactions and rule out extraneous variables.

Baker, Andrew H.

398

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

PubMed

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. PMID:21424392

Duydu, Yalç?n; Ba?aran, Nur?en; Üstünda?, Aylin; Aydin, Sevtap; Ünde?er, Ülkü; Ataman, Osman Yavuz; Aydos, Kaan; Düker, Yalç?n; Ickstadt, Katja; Waltrup, Britta Schulze; Golka, Klaus; Bolt, Hermann M

2011-06-01

399

Assessment of dynamic energy conversion systems for radioisotope heat sources  

NASA Astrophysics Data System (ADS)

The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were: Stirling; Brayton cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos multiattribute decision theory code. Three different heat source designs were used: case 1 with a beginning of life (BOL) source temperature of 640 C, case 2 with a BOL source temperature of 745 C, and case 3 with a BOL source temperature of 945 C. The Stirling engine system was the top-ranked system of case 1 and 2, closely followed by the ORC systems in case 1 and ORC plus thermoelectrics in case 2. The Brayton cycle system was top-ranked for case 3, with the Stirling engine system a close second. The use of (238) Pu in heat source sizes of 7500 W(t) is examined and it is found to be questionable because of cost and material availability and because of additional requirements for anlaysis of safeguards and critical mass.

Thayer, G. R.; Mangeng, C. A.

1985-06-01

400

Accelerator mass spectrometry for measurement of long-lived radioisotopes.  

PubMed

Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes (10)Be, (14)C,(26)A1, 36Cl, and (129)1 can now be measured in small natural samples having isotopic abundances in the range 10(-12) to 10(- 5) and as few as 10(5) atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of halflives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences. PMID:17740475

Elmore, D; Phillips, F M

1987-05-01

401

Accelerator Mass Spectrometry for Measurement of Long-Lived Radioisotopes  

NASA Astrophysics Data System (ADS)

Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes 10Be, 14C, 26Al, 36Cl, and 129I can now be measured in small natural samples having isotopic abundances in the range 10-12 to 10-15 and as few as 105 atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of half-lives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.

Elmore, David; Phillips, Fred M.

1987-05-01

402

Benefit of Small Radioisotope Power Systems for NASA Exploration Missions  

NASA Astrophysics Data System (ADS)

The increased use of smaller spacecraft over the last decade, in combination with studies of potential science applications, has suggested the need for Radioisotope Power Systems (RPSs) yielding much lower power levels than the 100 watt-scale devices used in the past. Small milliwatt to multiwatt-scale RPS units have the potential to extend the capability of small science payloads and instruments, and to enable many new mission applications. Such units could also find application in future human exploration missions involving use of monitoring stations and autonomous devices, similar to the ALSEP units deployed on the Moon during the Apollo program. Although flight-qualified RPS units in this size and power range do not presently exist, their potential to support a broad range of exploration tasks has led NASA and the Department of Energy (DOE) to consider the development of small-RPS units such that they might be available for missions by the early part of next decade. This paper summarizes the results of activities to date and provides possible options for future development.

Schmidt, George R.; Abelson, Robert D.; Wiley, Robert L.

2005-02-01

403

Thermal vacuum life test facility for radioisotope thermoelectric generators  

SciTech Connect

In the late 1970's, the Department of Energy (DOE) assigned Monsanto Research Corporation, Mound Facility, now operated by EG G Mound Applied Technologies, the responsibility for assembling and testing General Purpose Heat Source (GPHS) radioisotope thermoelectric generators (RTGs). Assembled and tested were five RTGs, which included four flight units and one non-flight qualification unit. Figure 1 shows the RTG, which was designed by General Electric AstroSpace Division (GE/ASD) to produce 285 W of electrical power. A detailed description of the processes for RTG assembly and testing is presented by Amos and Goebel (1989). The RTG performance data are described by Bennett, et al. (1986). The flight units will provide electrical power for the National Aeronautics and Space Administration's (NASA) Galileo mission to Jupiter (two RTGs) and the joint NASA/European Space Agency (ESA) Ulysses mission to study the polar regions of the sun (one RTG). The remaining flight unit will serve as the spare for both missions, and a non-flight qualification unit was assembled and tested to ensure that performance criteria were adequately met. 4 refs., 3 figs.

Deaton, R.L.; Goebel, C.J.; Amos, W.R.

1990-01-01

404

Assessment of dynamic energy conversion systems for radioisotope heat sources  

SciTech Connect

The use of dynamic conversion systems to convert the heat generated in a 7500 W(t) 90 Sr radioisotopic heat source to electricity is examined. The systems studies were Stirling; Brayton Cycle; three organic Rankines (ORCs) (Barber-Nichols/ORMAT, Sundstrand, and TRW); and an organic Rankine plus thermoelectrics. The systems were ranked for a North Warning System mission using a Los Alamos Multiattribute Decision Theory code. Three different heat source designs were used: case I with a beginning of life (BOL) source temperature of 640 C, case II with a BOL source temperature of 745/sup 0/C, and case III with a BOL source temperature of 945/sup 0/C. The Stirling engine system was the top-ranked system of cases I and II, closely followed by the ORC systems in case I and ORC plus thermoelectrics in case II. The Brayton cycle system was top-ranked for case III, with the Stirling engine system a close second. The use of /sup 238/Pu in heat source sizes of 7500 W(t) was examined and found to be questionable because of cost and material availability and because of additional requirements for analysis of safeguards and critical mass.

Thayer, G.R.; Mangeng, C.A.

1985-06-01

405

Light-weight radioisotope heater unit (LWRHU) impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s. {copyright} {ital 1998 American Institute of Physics.}

Reimus, M.A.; Rinehart, G.H.; Herrera, A.; Lopez, B.; Lynch, C.; Moniz, P. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1998-01-01

406

Light-weight radioisotope heater unit (LWRHU) impact tests  

SciTech Connect

The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s.

Reimus, M. A. H.; Rinehart, G. H.; Herrera, A.; Lopez, B.; Lynch, C.; Moniz, P. [Nuclear Materials Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1998-01-15

407

Radioisotope power system based on derivative of existing Stirling engine  

SciTech Connect

In a recent paper, the authors presented the results of a system design study of a 75-watt(c) RSG (Radioisotope Stirling Generator) for possible application to the Pluto Fast Flyby mission. That study was based on a Stirling engine design generated by MTI (Mechanical Technology, Inc.). The MTI design was a derivative of a much larger (13 kwe) engine that they had developed and tested for NASA`s LERC. Clearly, such a derivative would be a major extrapolation (downsizing) from what has actually been built and tested. To avoid that, the present paper describes a design for a 75-watt RSG system based on derivatives of a small (11-watt) engine and linear alternator system that has been under development by STC (Stirling Technology Company) for over three years and that has operated successfully for over 15,000 hours as of March 1995. Thus, the STC engines would require much less extrapolation from proven designs. The design employs a heat source consisting of two standard General Purpose Heat Source (GPHS) modules, coupled to four Stirling engines with linear alternators, any three of which could deliver the desired 75-watt(e) output if the fourth should fail. The four engines are coupled to four common radiators with redundant heatpipes for rejecting the engines` waste heat to space. The above engine and radiator redundancies promote system reliability. The paper describes detailed analyses to determine the effect of radiator geometry on system mass and performance, before and after an engine or heatpipe failure.

Schock, A.; Or, C.T.; Kumar, V. [Orbital Sciences Corp., Germantown, MD (United States)

1995-12-31

408

Over-the-road shock and vibration testing of the radioisotope thermoelectric generator transportation system  

SciTech Connect

Radioisotope Thermoelectric Generators (RTG) convert heat generated by radioactive decay into electricity through the use of thermocouples. The RTGs have a long operating life, are reasonably lightweight, and require little or no maintenance, which make them particularly attractive for use in spacecraft. However, because RTGs contain significant quantities of radioactive materials, normally plutonium-238 and its decay products, they must be transported in packages built in accordance with Title 10, Code of Federal Regulations, Part 71 (10 CFR 71). To meet these regulations, a RTG Transportation System (RTGTS) that fully complies with 10 CFR 71 has been developed, which protects RTGs from adverse environmental conditions during normal conditions of transport (e.g., shock, vibration, and heat). To ensure the protection of RTGs from shock and vibration loadings during transport, extensive over-the-road testing was conducted on the RTG`S to obtain real-time recordings of accelerations of the air-ride suspension system trailer floor, packaging, and support structure. This paper provides an overview of the RTG`S, a discussion of the shock and vibration testing, and a comparison of the test results to the specified shock response spectra and power spectral density acceleration criteria.

Becker, D.L.

1997-05-01

409

Kinetics of radioisotope exchange between brine and rock in a geothermal system  

SciTech Connect

A wide range of isotopes in the /sup 238/U, /sup 235/U, and /sup 232/Th decay chains was measured in geothermal brines collected from two production zones at 1898 and 3220 m in the Salton Sea Scientific Drilling Project well. High concentrations of radium, radon, and lead isotopes are generated and maintained by the input of these isotopes from solid phases into brine by both recoil and leaching processes, by the high chloride content of the brine which complexes radium and lead, and by the apparent absence of suitable unoccupied adsorption sites. In contrast, uranium, thorium, actinium, bismuth, and polonium isotopes all have low concentrations due to their efficient sorption from brine to rock. Measurements of short-lived isotopes in these decay series yield insights regarding the mechanisms controlling radioisotope exchange, and they permit estimation of rates of brine-rock interaction. For example, the /sup 228/Ac//sup 228/Ra activity ratio of 0.2 in brines indicates that the mean residence time of actinium in solution before sorption onto solid surfaces is less than 2.5 hours.

Hammond, D.E.; Zukin, J.G.; Teh-Lung Ku

1988-11-10

410

MECRIS: A compact ECRIS for ionization of noble gas radioisotopes at ISOLDE  

NASA Astrophysics Data System (ADS)

A very compact Electron Cyclotron Resonance Ion Source (ECRIS) for singly charged radioactive gases has been developed at ISOLDE/CERN. The radioisotopes are produced by fission, spallation, and fragmentation reactions induced via high-energy protons impacting on a thick target. The often short-lived radioactive elements required for ISOLDE physics diffuse out of the target, effuse through a transfer tube, and eventually reach the ionizing volume. An efficient ionization process is mandatory in view of the very small production cross sections of radioactive elements far from stability and fast ionization is desired to minimize decay losses. The MECRIS (Mono ECR ISOLDE) is intended for light noble gases (He, Ne, Ar, and Kr), which have low ionization efficiency in ordinary plasma ion sources, but also for gaseous molecular compounds of C, N, and O isotopes. We will report on the design and construction of the device, including magnetic field calculations and rf simulations. Results of the first tests performed with stable ion beams are presented.

Wenander, F.; Lettry, J.

2004-05-01

411

From Boron Cluster to Two-Dimensional Boron Sheet on Cu(111) Surface: Growth Mechanism and Hole Formation  

PubMed Central

As attractive analogue of graphene, boron monolayers have been theoretically predicted. However, due to electron deficiency of boron atom, synthesizing boron monolayer is very challenging in experiments. Using first-principles calculations, we explore stability and growth mechanism of various boron sheets on Cu(111) substrate. The monotonic decrease of formation energy of boron cluster BN with increasing cluster size and low diffusion barrier for a single B atom on Cu(111) surface ensure continuous growth of two-dimensional (2D) boron cluster. During growth process, hexagonal holes can easily arise at the edge of a 2D triangular boron cluster and then diffuse entad. Hence, large-scale boron monolayer with mixed hexagonal-triangular geometry can be obtained via either depositing boron atoms directly on Cu(111) surface or soft landing of small planar BN clusters. Our theoretical predictions would stimulate further experiments of synthesizing boron sheets on metal substrates and thus enrich the variety of 2D monolayer materials. PMID:24241341

Liu, Hongsheng; Gao, Junfeng; Zhao, Jijun

2013-01-01

412

From boron cluster to two-dimensional boron sheet on Cu(111) surface: growth mechanism and hole formation.  

PubMed

As attractive analogue of graphene, boron monolayers have been theoretically predicted. However, due to electron deficiency of boron atom, synthesizing boron monolayer is very challenging in experiments. Using first-principles calculations, we explore stability and growth mechanism of various boron sheets on Cu(111) substrate. The monotonic decrease of formation energy of boron cluster B(N) with increasing cluster size and low diffusion barrier for a single B atom on Cu(111) surface ensure continuous growth of two-dimensional (2D) boron cluster. During growth process, hexagonal holes can easily arise at the edge of a 2D triangular boron cluster and then diffuse entad. Hence, large-scale boron monolayer with mixed hexagonal-triangular geometry can be obtained via either depositing boron atoms directly on Cu(111) surface or soft landing of small planar BN clusters. Our theoretical predictions would stimulate further experiments of synthesizing boron sheets on metal substrates and thus enrich the variety of 2D monolayer materials. PMID:24241341

Liu, Hongsheng; Gao, Junfeng; Zhao, Jijun

2013-01-01

413

Detection of interstellar boron in front of kappa Orionus  

NASA Technical Reports Server (NTRS)

The detection of interstellar boron in the direction of kappa Ori, obtained with the Copernicus satellite telescope by observing the B II 1362.46-A resonance line is reported. A B/H concentration ratio of (1.5 + or - 0.7) x 10 to the -10th (2 standard deviation error bar) is obtained. The main uncertainty lies in the determination of the continuum of the star in that wavelength region, dominated by a broad stellar absorption feature. The value inferred for B/H in the interstellar medium is consistent with the solar and stellar values, believed to be the galactic value, and with the theory of the production of B by cosmic rays in the interstellar medium.

Meneguzzi, M.; York, D. G.

1980-01-01

414

Effect of Boron on Dynamic Change of Seed Yield and Quality Formation in Developing Seed of Brassica napus  

Microsoft Academic Search

Rapeseed (Brassica napus) is one of main oil crops in the world and also a potential bioenergy crop. Because of the sensitivity of Brassica napus to boron (B) deficiency and the wide distribution of low available-B soils in main areas of rapeseed production, more and more attention is being paid to the effect of B nutrition on yield and quality

M. Yang; L. Shi; F. S. Xu; Y. H. Wang

2009-01-01

415

Boron nitride: Composition, optical properties and mechanical behavior  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

416

Isothermal superplastic boronizing of high carbon and low alloy steels  

SciTech Connect

Superplasticity has been developed rapidly since the 1960`s. Superplasticity and superplastic deformation technique of steel and ferrous alloys offer a new method of forming complex parts for industrial applications, such as dies and gears. On the other hand, boronizing has long been used to improve the surface properties of dies and tools because boride has high hardness, good wear resistance, and good corrosion and oxidation resistance. Superplastic boronizing, a new technique, is the processes that combines boronizing with superplastic deformation. Because two processes become one, energy and time can be saved. In the present paper, the superplastic boronizing processes for commercial 0.9C-1Si-1Cr-Fe and 1C-1Cr-Fe steels are described first. Then, the microstructure and properties of specimens produced by using superplastic and conventional boronizing are compared. Finally, a physical model for superplastic boronizing processes is suggested.

Xu, C.H.; Gao, W. [Univ. of Auckland (New Zealand). Dept. of Chemical and Materials Engineering] [Univ. of Auckland (New Zealand). Dept. of Chemical and Materials Engineering; Xi, J.K. [Luoyang Inst. of Technology, Henan (China). Dept. of Materials Engineering] [Luoyang Inst. of Technology, Henan (China). Dept. of Materials Engineering

1996-02-01

417

Kinetics and mechanism of the deep electrochemical oxidation of sodium diclofenac on a boron-doped diamond electrode  

NASA Astrophysics Data System (ADS)

The kinetics and mechanism of the deep oxidation of sodium diclofenac on a boron-doped diamond electrode are studied to develop a technique for purifying wastewater from pharmaceutical products. The products of sodium diclofenac electrolysis are analyzed using cyclic voltammetry and nuclear magnetic resonance techniques. It is shown that the toxicity of the drug and products of its electrolysis decreases upon its deep oxidation.

Vedenyapina, M. D.; Borisova, D. A.; Rosenwinkel, K.-H.; Weichgrebe, D.; Stopp, P.; Vedenyapin, A. A.

2013-08-01

418

(Data in thousand metric tons of boric oxide (B2O3) unless otherwise noted) Domestic Production and Use: Two companies in southern California produced boron minerals, mostly sodium  

E-print Network

plants. The kernite was used for boric acid production and the tincal was used as a feedstock for sodium W W W Imports for consumption, gross weight: Borax 2 1 1 ( 2 ) ( 2 ) Boric acid 85 67 50 36 39 Colemanite 25 26 30 31 35 Ulexite 131 92 75 28 30 Exports, gross weight: Boric acid 221 248 303 171 250

419

Synthesis and properties of boron doped ZnO nanorods on silicon substrate by low-temperature hydrothermal reaction  

NASA Astrophysics Data System (ADS)

Boron doped ZnO nanorods were fabricated by hydrothermal technique on silicon substrate covered with a ZnO seed layer. It is found that the concentration of boric acid in the reaction solution plays a key role in varying the morphology and properties of the products. The growth rate along the [0 0 0 1] orientation (average size in diameter) of the doped ZnO nanorods decreased (increased) with the increase of boric acid concentration. Based on the results of XRD, EDX and XPS, it is demonstrated that the boron dopants tend to occupy the octahedral interstice sites. The photoluminescence of the ZnO nanorods related to boron doping are investigated.

Yu, Qi; Li, Liuan; Li, Hongdong; Gao, Shiyong; Sang, Dandan; Yuan, Jujun; Zhu, Pinwen

2011-05-01

420

Research of boron films deposited on different substrates  

NASA Astrophysics Data System (ADS)

Semiconductor detector that incorporate neutron reactive material within the same detector demonstrates a new method for neutron dosimetry and boron neutron reactive therapy seems to be a promising treatment. Boron films were deposited on single crystalline silicon, glass, and CVD diamond film by magnetron sputtering, close-space sublimation and vacuum evaporation. The properties of the samples were characterized by SEM, which shows vacuum evaporation method is suitable for depositing high quality boron films.

Zhou, Jie; Wang, Linjun; Huang, Jian; Tang, Ke; Ren, Bing; Yao, Beiling; Xia, Yiben

2013-09-01

421

Fracture toughness of borides formed on boronized ductile iron  

Microsoft Academic Search

In this study, fracture toughness properties of boronized ductile iron were investigated. Boronizing was realized in a salt bath consisting of borax, boric acid and ferro-silicon. Boronizing heat treatment was carried out between 850 and 950 °C under the atmospheric pressure for 2–8 h. Borides e.g. FeB, Fe2B formed on ductile iron was verified by X-ray diffraction (XRD) analysis, SEM

Ugur Sen; Saduman Sen; Sakip Koksal; Fevzi Yilmaz

2005-01-01

422

Boron removal from water by complexation to polyol compounds  

Microsoft Academic Search

Boron is an important micronutrient for plants, animals and humans, although the range between deficiency and excess is narrow. The use of desalinated water and treated wastewater for irrigation may result in excess boron. In aqueous environments (i.e. neutral pH) boron is mainly present as boric acid, which is mostly undissociated and therefore only partially rejected by desalination membranes.Boric acid\\/borate

Nitzan Geffen; Raphael Semiat; Moris S. Eisen; Yael Balazs; Ilan Katz; Carlos G. Dosoretz

2006-01-01

423

The Sorption Capacity of Boron on Anionic-Exchange Resin  

Microsoft Academic Search

Boron sorption capacities on anionic-exchange resins vary with temperature, concentration, and resin crosslinkage. A semiempirical correlation, developed from boron solution chemistry, is presented to account for these variations. The relationship, based on boron chemistry and changes in Gibb's energy, can be stated approximately as Q = a1CBz exp[-(a4T + a5T + a6z )]. Correlation parameters, which vary with resin type,

JIDONG LOU; GARY L. FOUTCH; JUNG WON NA

1999-01-01

424

Natural Radioactivity of Boron Added Clay Samples  

SciTech Connect

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

Akkurt, I.; Guenoglu, K. [Sueleyman Demirel University, Faculty of Arts and Sciences, Dept. of Physics, Isparta (Turkey); Canakcii, H. [Gaziantep University, Engineering Faculty, Civil Engineering Dept., Gaziantep (Turkey); Mavi, B. [Amasya University, Faculty of Arts and Sciences, Dept. of Physics, Amasya (Turkey)

2011-12-26

425

Techniques for increasing boron fiber fracture strain  

NASA Technical Reports Server (NTRS)

Improvement in the strain-to-failure of CVD boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. The results of three methods are presented in which etching and thermal processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment induced surface flaws were removed from 203 micrometers (8 mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment induced contraction on the core flaw. Commercial feasibility considerations suggest as the most cost effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed are presented and discussed both for high vacuum and argon gas heat treatment environments.

Dicarlo, J. A.

1977-01-01

426

Novel spherical boron clusters and structural transition from 2D quasi-planar structures to 3D  

E-print Network

- hedra. It is very natural to believe that - like carbon - boron also can form molecular allotropes materials mainly consisting of pure or mixed boron, carbon, nitrogen, boron-hydrogen and metal-boron types and form molecular networks. Unlike carbon, bulk boron cannot be found in nature and all known boron

Pandey, Ravi

427

Reaction of arylethanals with boron tribromide  

Microsoft Academic Search

Treatment of arylethanals 1 with boron tribromide give 2-phenylnaphthalenes 2 or 1,2,9,10-tetrahydro-1,9-epoxydibenzo[a,e]cyclooctenes 3 by a tandem aldol condensation-intramolecular Friedel-Crafts cyclization or a condensation at the O-position followed by a double Friedel-Crafts alkylation respectively. In all cases, a total demethylation of the methoxy groups occurs.

Romain Dupont; Philippe Cotelle

1998-01-01

428

Kinetic analysis of boron transport in Chara  

Microsoft Academic Search

.   The permeability of biological membranes to boric acid was investigated using the giant internodal cells of the charophyte\\u000a alga Chara corallina (Klein ex Will. Esk. R.D. Wood). The advantage of this system is that it is possible to distinguish between membrane transport\\u000a of boron (B) and complexing of B by plant cell walls. Influx of B was found to

James C. R. Stangoulis; Robert J. Reid; Patrick H. Brown; Robin D. Graham

2001-01-01

429

Impact of boron deficiency on Xenopus laevis  

Microsoft Academic Search

The toxicity of boron has been understood for many years. However, limited data currently exist concerning the nutritional\\u000a essentiality of B in chordates. Results from an ongoing research program evaluating the nutritional essentiality of B in the\\u000a South African clawed frog, Xenopus laevis, found that X. laevis fed a low-B diet in a low-B culture media produced a substantially higher

Douglas J. Fort; Robert L. Rogers; Daniel W. McLaughlin; Chris M. Sellers; Christian L. Schlekat

2002-01-01

430

Isotope ratio determination in boron analysis  

Microsoft Academic Search

Traditionally, boron (B) isotope ratios have been determined using thermal ionization mass spectrometry (TIMS) and, to some\\u000a extent, secondary ion mass spectrometry (SIMS). Both TIMS and SIMS use a high-resolution mass analyzer, but differ in analyte\\u000a ionization methods. TIMS uses electrons from a hot filament, whereas SIMS employs an energetic primary ion beam of Ga+, Cs+, or O- for analyte

Ram N. Sah; Patrick H. Brown

1998-01-01

431

Tunneling spectroscopy of graphene boron nitride heterostructures  

NASA Astrophysics Data System (ADS)

We report on the fabrication and measurement of a graphene tunnel junction using hexagonal boron nitride as a tunnel barrier between graphene and a metal gate. The tunneling behavior into graphene is altered by the interactions with phonons and the presence of disorder. We extract properties of graphene and observe multiple phonon-enhanced tunneling thresholds. Finally, differences in the measured properties of two devices are used to shed light on mutually-contrasting previous results of scanning tunneling microscopy in graphene.

Goldhaber-Gordon, David

2012-02-01

432

Boronate affinity chromatography of cells and biomacromolecules using cryogel matrices.  

PubMed

Boronate affinity chromatography involves the interaction between cis-diol containing molecules and the hydroxyl group of boronate. Boronate affinity based cryogel chromatography matrices have been developed and the ligands were immobilized by two methods i.e., grafting of the boronate ligand on to the matrix and by copolymerization of monomer containing boronate with other co-monomer. The boronate grafted cryogel column was used to capture adherent and non-adherent cells and the captured cells were recovered at different fructose concentrations as an eluting agent, in chromatography mode. It was found that the adherent cells could be recovered at relatively higher fructose concentration (0.5M) than non-adherent cells which could be recovered by using low fructose concentration (0.1M). This might be due to the difference in the content of glycoprotein in adherent and non-adherent cells. In this way a new separation method can be devised for the fractionation of adherent and non-adherent cells. In another study, a copolymerized boronate cryogel column was developed for the separation of RNA from the bacterial crude extract without any pre-processing. RNA molecules were specifically retained in the cryogel column due to interaction between 2,3' diol group of ribose sugar in RNA and the hydroxyl group of boronate. The DNA molecules were passed through the column uninteracted due to absence of 2'-hydroxyl group. Later, bound RNA molecules were recovered from the boronate affinity cryogel column. PMID:23040394

Srivastava, Akshay; Shakya, Akhilesh Kumar; Kumar, Ashok

2012-12-10

433

Effect of dietary boron on the aging process.  

PubMed Central

Total boron concentrations in Drosophila changed during development and aging. The highest concentration of boron was found during the egg stage, followed by a decline during the larval stages. Newly emerged flies contained 35.5 ppm boron. During the adult stage the boron concentration increased by 52% by 9 weeks of age. Adding excess dietary boron during the adult stage decreased the median life span by 69% at 0.01 M sodium borate and by 21% at 0.001 M sodium borate. Lower concentrations gave small but significant increases in life span. Supplementing a very low boron diet with 0.00025 M sodium borate improved life span by 9.5%. The boron contents of young and old mouse tissues were similar to those of Drosophila and human samples. Boron supplements of 4.3 and 21.6 ppm in the drinking water, however, did not significantly change the life span of old mice fed a diet containing 31.1 ppm boron. PMID:7889879

Massie, H R

1994-01-01

434

Laser Boronizing of Stainless Steel with Direct Diode Laser  

NASA Astrophysics Data System (ADS)

Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050°C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of stainless steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope, electron probe micro analyser(EPMA) and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of NiB, CrB, FeB and Fe2B, and get wear resistance.

Kusuhara, Takayoshi; Morimoto, Junji; Abe, Nobuyuki; Tsukamoto, Masahiro

435

Interplanetary Sample Return Missions Using Radioisotope Electric Propulsion  

NASA Technical Reports Server (NTRS)

Solar electric propulsion (SEP) is being used for a variety of planetary missions sponsored by ESA, JAXA, and NASA and nuclear electric propulsion (NEP) is being considered for future, flagship-class interplanetary missions. Radioisotope electric propulsion (REP) has recently been shown to effectively complement SEP and NEP for missions to high-AU targets with modest payload requirements. This paper investigates the application of an advanced REP for a sample return from the comet Tempel 1. A set of mission and system parameters are varied with the goal of quantifying their impact on total mission payload. Mission parameters considered include trip-time and Earth return entry interface speed of the sample return system. System parameters considered include launch vehicle, power level of spacecraft at beginning of mission, and thruster specific impulse. For the baseline case of Atlas 401 and REP power level of 750 W, the mission time was 12 years, the payload was 144 kg, and the missions optimized to a single specific impulse generally within Hall ion thruster range. Other cases were investigated in support of graduate studies, and include the larger Atlas 551 launch vehicle and extended power level to 1 kW. The Atlas 551 cases tended to optimize dual specific impulses generally in the Hall ion thruster range for both legs of the mission. A power level of at least 1-kW and trip-time of approximately 11 years was required to obtain a total science payload close to 320 kg for the Atlas 401 launch vehicle. An Atlas 551 launch vehicle yielded a science payload of approximately 540 kg for the case of 1-kW of power and an 11-year trip time, and nearly 250 kg of science payload for the case of 1-kW of power and a 6-year trip time. Results are also reported indicating the performance ramifications of meeting a reduced Earth entry interface velocity constraint.

Williams, R.; Gao, Y.; Kluever, C. A.; Capples, M.; Belcher, J.

2005-01-01

436

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

DOEpatents

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

Halverson, Danny C. (Manteca, CA); Pyzik, Aleksander J. (Seattle, WA); Aksay, Ilhan A. (Seattle, WA)

1986-01-01

437

Spallation of Hot Pressed Boron Carbide Ceramic  

NASA Astrophysics Data System (ADS)

This work describes the results of plane shock wave spallation experiments conducted on Hot Pressed Boron Carbide marketed by Cercom as PAD B4C (>99% pure). Density of the material was determined to be 2.508 plus-or-minus0.016 Mg/m3 while the longitudinal and shear wave velocities were measured at 13.49 plus-or-minus0.18 km/s and 8.65 plus-or-minus0.08 km/s, respectively. Spallation thresholds calculated from the measured "pull-back" velocity were determined up to an impact stress of 15.5 GPa. The values of spall threshold do not vary significantly with impact pressure but do exhibit a pulse width dependency indicating a time dependent generation of defects. The value of spall strength of boron carbide is 0.35 plus-or-minus 0.07 GPa when shocked between 2 and 15.5 GPa. The values of release impedance lie between 33 and 37 Gg/m2s and are in good agreement with the longitudinal impedance of 33.8 plus-or-minus0.5 Gg/m2s at the ambient condition measured ultrasonically. The free-surface velocity profiles obtained from these experiments were numerically simulated using Rajendran-Grove (R-G) ceramic model. The paper provides the values of material constants required by the R-G ceramic model for boron carbide.

Bartkowski, Peter T.; Dandekar, Dattatraya P.; Grove, David J.

2002-07-01