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1

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

2

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

3

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

4

Production and Development of Radioisotopes.  

National Technical Information Service (NTIS)

Radioisotopes produced by TRIGA MARK III REACTOR were supplied to hospitals, science institutes, universities, nondestructive test industries and so on in Korea. In 1984, 385.5 Ci (207 x 10 sup 6 won) of non-sealed radioisotopes, mainly radiopharmaceutica...

Y. K. Kim, J. D. Lee, H. S. Bang, H. S. Han, M. S. Park

1985-01-01

5

Production and Development of Radioisotopes.  

National Technical Information Service (NTIS)

In 1981, 224.7 Ci of non-sealed radioisotopes mainly radio pharmaceuticals such as sup(99m)Tc, exp 131 I, exp 198 Au colloid, and 707.5 Ci of exp 192 Ir as a radiation source were produced and supplied to users in Korea. The activity of non-sealed radiois...

Y. K. Kim, J. D. Lee, H. S. Han, H. S. Bang, S. H. Lee

1982-01-01

6

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

7

Activities study of PET's radioisotopes production with plasma focus devices  

Microsoft Academic Search

In recent years, the request for radioisotopes has been increasing steadily. Experiments in the past five years have demonstrated production of Short-Lived radioisotopes (SLRs) with a plasma focus devices. Radioisotope activity only a few microcuries have been obtained from single discharges in small scale plasma focus machines and at high pulse repetition rate in large and high energy plasma focus

V. Razazi; R. M. Gharehbagh

2010-01-01

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

77 FR 21592 - Guidelines for Preparing and Reviewing Licensing Applications for the Production of Radioisotopes  

Federal Register 2010, 2011, 2012, 2013

...and Content,'' for the production of radioisotopes and NUREG-1537...Acceptance Criteria,'' for the production of radioisotopes. The ISG...license for a radioisotope production facility. DATES: Comments...publicly disclosed. The NRC posts all comment submissions...

2012-04-10

10

A 5 MW TRIGA reactor design for radioisotope production  

Microsoft Academic Search

The production and preparation of commercial-scale quantities of radioisotopes has become an important activity as their medical and industrial applications continue to expand. There are currently various large multipurpose research reactors capable of producing ample quantities of radioisotopes. These facilities, however, have many competing demands placed upon them by a wide variety of researchers and scientific programs which severely limit

Anthony R. Veca; William L. Whittemore

1994-01-01

11

A 5 MW TRIGA reactor design for radioisotope production  

SciTech Connect

The production and preparation of commercial-scale quantities of radioisotopes has become an important activity as their medical and industrial applications continue to expand. There are currently various large multipurpose research reactors capable of producing ample quantities of radioisotopes. These facilities, however, have many competing demands placed upon them by a wide variety of researchers and scientific programs which severely limit their radioisotope production capability. A demonstrated need has developed for a simpler reactor facility dedicated to the production of radioisotopes on a commercial basis. This smaller, dedicated reactor could provide continuous fission and activation product radioisotopes to meet commercial requirements for the foreseeable future. The design of a 5 MW TRIGA reactor facility, upgradeable to 10 MW, dedicated to the production of industrial and medical radioisotopes is discussed. A TRIGA reactor designed specifically for this purpose with its demonstrated long core life and simplicity of operation would translate into increased radioisotope production. As an example, a single TRIGA could supply the entire US needs for Mo-99. The facility is based on the experience gained by General Atomics in the design, installation, and construction of over 60 other TRIGAs over the past 35 years. The unique uranium-zirconium hydride fuel makes TRIGA reactors inexpensive to build and operate, reliable in their simplicity, highly flexible due to unique passive safety, and environmentally friendly because of minimal power requirements and long-lived fuel. (author)

Veca, Anthony R.; Whittemore, William L. [General Atomics, San Diego, CA (United States)

1994-07-01

12

Alternate methods for the production of radioisotopes  

Microsoft Academic Search

The use of radioisotopes for diagnostic and therapeutic clinical applications has increased in the past decade. The growth has been in two areas: the use of {sup 99m}Tc for gamma-ray imaging and the use of ¹⁸F in positron emission tomography (PET). The {sup 99m}Tc (6.01 h) is a daughter of the longer-lived precursor ⁹⁹Mo (65.9 h), which is produced in

S. D. Howe; J. D. Metzger; G. A. Smith

1996-01-01

13

Use of circulating solution reactors for production of radioisotopes  

Microsoft Academic Search

This paper presents results from a series of analyses aimed at investigating the use of circulating solution reactors for production of medical and other radioisotopes. To date, several options have been proposed and investigated. These alternatives include the use of the Annular Core Research Reactor facility at Sandia National Laboratories and the Medical Isotopes Production Reactor (MIPR) by Babcock and

C. R. Hills; A. S. Heger

1997-01-01

14

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

15

Studies on Fundamental Properties of Alumina Adsorbent for Radioisotope Production  

Microsoft Academic Search

Some fundamental properties of chromatographic alumina, used for the preparation of radioisotope generators and for the separation of fission products, were examined in connection with pretreatment procedures prescribed for the alumina to improve its properties in respect of alumina dissolution by certain eluants, its adsorption capacity for certain ions, and the effects of differences in the mode of storage.The commercially

Satoko TAKAHASHI; Eiji SHIKATA; Hiroshi AMANO

1970-01-01

16

Production and Development of Radiation Sources and Radioisotopes.  

National Technical Information Service (NTIS)

In 1979, 96,925 mCi of non sealed radioisotopes mainly radiopharmaceuticals were produced and supplied to users in the country. The amounts of production have increased 27% more than those of previous year partly owing to re-operation of TRIGA Mark III (2...

Y. K. Kim J. D. Lee Y. J. You

1980-01-01

17

Production of radioisotopes in the ORNL 86-inch cyclotron  

Microsoft Academic Search

The radioisotope production facilities and programs of the 86-Inch Cyclotron are reviewed in this presentation. The 86-Inch Cyclotron is designed to accelerate protons to a maximum energy of 22 MeV for internal targets. These protons are used to bombard metals that are electroplated, potted or soldered to water-cooled plates. Additionally, metals and inorganic compounds are bombarded in water-cooled tube targets.

J. W. Terry

1981-01-01

18

High intensity H- cyclotrons for radioisotope production  

Microsoft Academic Search

A description is given of Cyclone 30, a 30-MeV, H- cyclotron for radioscope production, designed for extremely high extracted beam intensity (500 ?A) and low power consumption (less than 100 kW with a 15-kW extracted beam). The Cyclone 30 prototype has now been operational for years at Louvain-La-Neuve and has achieved all design goals while demonstrating very high reliability. The

J. L. Bol; A. Chevalier; E. Conrad; Y. Jongen; M. Lacroix; G. Lannoye; T. Ledocte; A. Ninane; G. Rijckewaert; S. Zaremba

1989-01-01

19

Radioisotope-production facility at JAEA-TIARA used for medical and plant physiological research  

Microsoft Academic Search

A radioisotope-production facility at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) of the Japan Atomic Energy Agency (JAEA) allows us to produce radioisotopes using accelerated beam from an AVF cyclotron. The facility has been constructed for research and development of potentially useful radioisotopes in medical research and physiological studies of plants. Experiments in these fields require a variety

N. S. Ishioka; S. Watanabe; H. Matsuoka; S. Matsuhashi

2005-01-01

20

Lightweight Radioisotope Heater Unit (LWRHU) production for the Cassini mission  

SciTech Connect

The Lightweight Radioisotope Heater Unit (LWRHU) is a {sup 238}PuO{sub 2} fueled heat source designed to provide a thermal watt of power for space missions. The LWRHU will be used to maintain the temperature of various components on the spacecraft at the required level. The heat source consists of a {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh capsule, a pyrolytic graphite insulator, and a woven graphite aeroshell assembly. Los Alamos has fabricated 180 heater units, which will be used on the Cassini mission. This report summarizes the specifications, fabrication processes, and production data for the heat sources fabricated at Los Alamos.

Rinehart, G.H.

1996-06-01

21

Radio-isotope production using laser Wakefield accelerators  

SciTech Connect

A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu{sup 61} was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator.

Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

2001-07-27

22

Current status and future plan for the production of radioisotopes using HANARO Research Reactor  

Microsoft Academic Search

The Korea Atomic Energy Research Institute (KAERI) completed the High-flux Advanced Neutron Application Reactor (HANARO) in 1995 and the radioisotope production facilities(RIPF) in 1997. Many devices and handling tools were developed and applied for the production of radioisotopes. Emphasis on RI production plan was placed on the development of new radiopharmaceuticals, the development of new radiation sources for industrial use

H. S. Han; W. K. Cho; U. J. Park; Y. D. Hong; K. B. Park

2003-01-01

23

A compact high-power proton linac for radioisotope production  

SciTech Connect

Conventional designs for proton linacs use a radiofrequency quadrupole (RFQ), followed by a drift-tube linac (DTL). For higher final beam energies, a coupled cavity linac (CCL) follows the DTL. A new structure, the coupled-cavity drift-tube linac (CCDTL) combines features of an Alvarez DTL and the CCL. Operating in a {pi}/2 structure mode, the CCDTL replaces the DTL and part of the CCL for particle velocities in the range 0.1 < {beta} < 0.5. The authors present a design concept for a compact linac using only an RFQ and a CCDTL. This machine delivers a few mA of average beam current at a nominal energy of 70 MeV and is well suited for radioisotope production.

Takeda, H.; Billen, J.H.; Nath, S.; Stovall, J.E.; Wood, R.L.; Young, L.M.

1995-05-01

24

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

25

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

26

Boron modified molybdenum silicide and products  

DOEpatents

A boron-modified molybdenum silicide material is disclosed 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. 7 figs.

Meyer, M.K.; Akinc, M.

1999-02-02

27

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

28

Boron modified molybdenum silicide and products  

Microsoft Academic Search

A boron-modified molybdenum silicide material is disclosed 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 MoSi phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum

M. K. Meyer; M. Akinc

1999-01-01

29

Boron modified molybdenum silicide and products  

Microsoft Academic Search

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

Mitchell K. Meyer; Mufit Akinc

1999-01-01

30

Development of the radioisotope production facility for the KMRR -Studies on application of radiation and radioisotopes-.  

National Technical Information Service (NTIS)

It's been 30 years since to start RI and labelled compound production in this country. But it is so limited to certain nuclide due to small research reactor and its RI production facilities. In order to upgrade and expand RI, it is necessary to operate hi...

J. B. Lee J. S. Woo K. C. Kang S. T. Baek U. S. Jeong

1994-01-01

31

Preliminary results on the production of short-lived radioisotopes with a Plasma Focus device  

Microsoft Academic Search

An experimental campaign was conducted to assess the feasibility of short-lived radioisotope (SLR) production within the pulsed discharges of a Plasma Focus (PF) device. This so-called endogenous production technique rests on the exploitation of nuclear reactions for the creation of SLR directly within the plasma, rather than on irradiating an external target. Until now only one research group has published

E. Angeli; A. Tartari; M. Frignani; D. Mostacci; F. Rocchi; M. Sumini

2005-01-01

32

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

Microsoft Academic Search

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

Suresh C. Srivastava; Leonard F. Mausner

1994-01-01

33

An on-line information system for radioisotope thermal generator production  

NASA Astrophysics Data System (ADS)

An on-line production information system has been designed to support radioisotope thermal generator assembly and testing in a new facility being built at the Department of Energy Hanford Site in Washington State. This system is intended to make handling the large volumes of information associated with radioisotope thermal generator production and certification more efficient with less opportunity for error than traditional paper methods. It provides for tracking materials, implementing work procedures directly from computer terminals, and cross referencing among materials, procedures, and other documents related to production. This system will be implemented on a network of microcomputers using UNIXTM for its operating system. It has been designed to allow increased capabilities to be added as operating experience with the new facility dictates.

Kiebel, Gary R.; Wiemers, Michael J.

1991-01-01

34

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

35

Boron  

MedlinePLUS

... and muscle coordination. Women sometimes use capsules containing boric acid, the most common form of boron, inside the vagina to treat yeast infections. People also apply boric acid to the skin as an astringent or to ...

36

Radioisotope production experience at the Cintichem 5-MW research reactor  

SciTech Connect

The Cintichem radiochemical production facility was constructed in the late 1950s and became operational in October of 1961. The facility was originally designed and constructed by Union Carbide Corporation for research and development of nuclear technology with the ultimate objective of exploiting it commercially. Research projects were conducted in the fields of direct energy conversion for the production of electric power and chemical synthesis, neutron spectrometry, nuclear fuel cycle development, and radiochemical production. Radiochemical production for medical applications was the only development project that was successfully commercialized.

McGovern, J.J. (Cintichem, Inc., Tuxedo, NY (United States))

1993-01-01

37

A prototype on-line work procedure system for radioisotope thermoelectric generator production  

SciTech Connect

An on-line system to manage work procedures is being developed to support radioisotope thermoelectric generator (RTG) assembly and testing in a new production facility. This system implements production work procedures as interactive electronic documents executed at the work site with no intermediate printed form. It provides good control of the creation and application of work procedures and provides active assistance to the worker in performing them and in documenting the results. An extensive prototype of this system is being evaluated to ensure that it will have all the necessary features and that it will fit the user's needs and expectations. This effort has involved the Radioisotope Power Systems Facility (RPSF) operations organization and technology transfer between Westinghouse Hanford Company (Westinghouse Hanford) and EG G Mound Applied Technologies Inc. (Mound) at the US Department of Energy (DOE) Mound Site. 1 ref.

Kiebel, G.R.

1991-09-01

38

Effects of reaction parameters on boron carbide powder production by the carbothermic process  

Microsoft Academic Search

Experiments were carried out to determine suitable reaction parameters for carbothermic production of boron carbide from relatively fine reactants and relatively low temperatures, compared with traditional production in an Acheson furnace or in an electric arc furnace. Effects of carbon type and particle size, boron oxide particle size, boron oxide-to-carbon ratio, and temperature were determined.

D. L. Belitskus; R. J. Campbell; S. Y. Tzeng

1991-01-01

39

Production of Radioisotopic gamma Radiation Sources in JAERI.  

National Technical Information Service (NTIS)

The present state of production of gamma radiation sources in Japan Atomic Energy Research Institute (JAERI) is described. Sources of exp 192 Ir, exp 60 Co and exp 170 Tm for industrial and exp 198 Au and exp 192 Ir for medical applications are produced a...

H. Katoh H. Kogure K. Suzuki

1980-01-01

40

Reactivity analysis of solution reactors for medical-radioisotope production  

Microsoft Academic Search

One of the primary methods to produce medical isotopes, such as 99Mo, is by irradiation of uranium targets in heterogeneous reactors. Solution reactors present a potential alternative to produce medical isotopes. The medical isotope production reactor concept has been proposed to produce medical isotopes with lower uranium consumption and waste than the corresponding fuel consumption and waste in heterogeneous reactors.

Francisco J. Souto; Robert H. Kimpland

2004-01-01

41

Manipulation of in Vivo Sorbitol Production Alters Boron Uptake and Transport in Tobacco  

Microsoft Academic Search

Recent evidence that some species can retranslocate boron as complexes with sugar alcohols in the phloem suggests a possible mechanism for enhancing boron efficiency. We investigated the relationship between sugar alcohol (sorbitol) content, boron uptake and distribution, and translocation of foliar-applied, isotopically enriched 10B in three lines of tobacco (Nicotiana tabacum) plants differing in sorbitol production. In tobacco line S11,

Nacer Bellaloui; Patrick H. Brown; Abahaya M. Dandekar

1999-01-01

42

Recovery of boron of the sieve reject in the production of borax  

Microsoft Academic Search

Boron ores are one of the most important underground richness of Turkey. Various boron compounds are produced from these ores. The most important one of them is borax. During the borax production process, a large quantity of the boron oxide (B2O3) is discharged by the trommel sieve waste (TSW). Also, this waste causes different environmental problems when it discharged directly

Recep Boncukcuo?lu; M. Muhtar Kocakerim; Erdem Kocada?istan; M. Tolga Yilmaz

2003-01-01

43

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

44

Production and purification of organic reagents labeled with radioisotopes produced by an accelerator  

Microsoft Academic Search

We studied the production of nine typical organic analytical reagents labeled with11C,13N and18F by irradiation with charged particles and bremsstrahlung and the purification of labeled compounds with HPLC and sublimation.\\u000a As a result, we found that six reagents, ?-naphthol, ?-naphthol, quinoline, ?-nitroso-?-naphthol, 8-hydroxyquinoline, and\\u000a 1,10-phenanthroline H2O could be labeled with11C by bombarding a mixture of each reagent and boron with

K. Shikano; K. Masumoto; T. Ohtsuki; M. Katoh

1999-01-01

45

Preliminary results on the production of short-lived radioisotopes with a Plasma Focus device.  

PubMed

An experimental campaign was conducted to assess the feasibility of short-lived radioisotope (SLR) production within the pulsed discharges of a Plasma Focus (PF) device. This so-called "endogenous production" technique rests on the exploitation of nuclear reactions for the creation of SLR directly within the plasma, rather than on irradiating an external target. Until now only one research group has published data relevant to PF endogenous production of SLR, and the data seem to confirm that the PF has the capability to breed SLR. The campaign demonstrated production of (15)O, (17)F and (13)N from the (14)N(d,n)(15)O, (12)C(d,n)(13)N and (16)O(d,n)(17)F reactions. A 7kJ, 17kV Mather-type PF was operated with natural nitrogen, oxygen, CO(2) and deuterium in the vacuum chamber. Results to date confirm that, with a PF of this type, up to 1microCi of SLRs per discharge can be obtained. PMID:15985375

Angeli, E; Tartari, A; Frignani, M; Mostacci, D; Rocchi, F; Sumini, M

2005-01-01

46

Establishment of a Manufacturing Process for the Production of Boron/Epoxy Tape.  

National Technical Information Service (NTIS)

This report covers work done on a program to establish an improved manufacturing process for boron/epoxy tape, specifically oriented towards the production of prepreg tapes for automatic tape laying machines. The program efforts were directed toward the a...

T. Schoenberg R. Loszewski E. McQuaid R. Stout G. Van Y

1973-01-01

47

THE IEA-R1 RESEARCH REACTOR: 50 YEARS OF OPERATING EXPERIENCE AND UTILIZATION FOR RESEARCH, TEACHING AND RADIOISOTOPES PRODUCTION  

Microsoft Academic Search

This paper describes almost 50 years of operating e xperience and utilization of the IEA-R1 research reactor for research, teaching and radioisotopes production. The current and future program of upgrading the reactor is also described. IEA-R1 research reactor at the Instituto de Pesquisas Energticas e Nucleares (IPEN), Sao Paulo, Brazil is the largest power research reactor in Brazil, with a

Rajendra N. Saxena

48

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

49

Radioisotope Power System Materials Production and Technology Program Tasks. Quarterly Technical Progress Report for April through June 2000.  

National Technical Information Service (NTIS)

The Office of Space and Defense Power Systems (OSDPS) ofthe Department of Energy (DOE) provides Radioisotope Power Systems (RPS) for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators were s...

2001-01-01

50

Quarterly Technical Progress Report of the Radioisotope Power System Materials Production and Technology Program Tasks for July through September 2000.  

National Technical Information Service (NTIS)

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...

2000-01-01

51

Quarterly Technical Progress Report of Radioisotope Power System Materials Production and Technology Program tasks for April 2000 through June 2000  

SciTech Connect

The Office of Space and Defense Power Systems (OSDPS) 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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. For the Cassini Mission, for example, ORNL was involved in the production of carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVSs) and weld shields (WSs). This quarterly report has been divided into three sections to reflect program guidance from OSDPS for fiscal year (FY) 2000. The first section deals primarily with maintenance of the capability to produce flight quality carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, clad vent sets (CVSs), and weld shields (WSs). In all three cases, production maintenance is assured by the manufacture of limited quantities of flight quality (FQ) components. The second section deals with several technology activities to improve the manufacturing processes, characterize materials, or to develop technologies for two new RPS. The last section is dedicated to studies of the potential for the production of 238Pu at ORNL.

Moore, J.P.

2000-10-23

52

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

53

Production of medical radioisotopes in the ORNL high flux isotope reactor (HFIR) for cancer treatment and arterial restenosis therapy after PICA  

NASA Astrophysics Data System (ADS)

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. First beginning operation in 1965, the high thermal neutron flux (2.51015 neutrons/cm2/sec at 85 MW) and versatile target irradiation and handling facilities provide the opportunity for production of a wide variety of neutron-rich medical radioisotopes of current interest for therapy. 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 (22 24 days) 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.; Beets, A. L.; Mirzadeh, S.; Alexander, C. W.; Hobbs, R. L.

1999-01-01

54

Production of medical radioisotopes in the ORNL high flux isotope reactor (HFIR) for cancer treatment and arterial restenosis therapy after PICA  

NASA Astrophysics Data System (ADS)

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. First beginning operation in 1965, the high thermal neutron flux (2.51015 neutrons/cm2/sec at 85 MW) and versatile target irradiation and handling facilities provide the opportunity for production of a wide variety of neutron-rich medical radioisotopes of current interest for therapy. 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-117 m 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 (22-24 days) 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-117 m 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.; Beets, A. L.; Mirzadeh, S.; Alexander, C. W.; Hobbs, R. L.

1999-01-01

55

Ignition and combustion of boron particles in hydrogen\\/oxygen combustion products at 30 to 150 atmospheres  

Microsoft Academic Search

The ignition and combustion of crystalline boron particles is studied at high pressures and temperatures in the combustion products of nitrogen diluted premixed hydrogen\\/oxygen mixtures at nearly constant pressure conditions. Particle ignition and combustion are monitored optically by measuring combusting particle emissions. The methodology is used to measure the ignition delay and combustion times of 24 micron boron particles over

Robert Oliver Foelsche

1998-01-01

56

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

57

Quarterly Technical Progress Report of Radioisotope Power System Materials Production and Technology Program tasks for April 2000 through June 2000  

Microsoft Academic Search

The Office of Space and Defense Power Systems (OSDPS) 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 for deep space missions including the Cassini Mission launched in October of 1997 to

2000-01-01

58

Influence of oxygen on defect production in electron-irradiated, boron-doped silicon  

NASA Technical Reports Server (NTRS)

Deep level transient spectroscopy (DLTS) measurements were made on float-zone and crucible-grown, boron-doped silicon irradiated with 1-MeV electrons. The minority carrier trap attributed to a boron-related state, was not seen in low-resistivity, float-zone silicon. However, a new majority carrier trap was observed in these samples. In the case of more lightly doped material the minority carrier trap was present, and its introduction rate was lower in float-zone than in crucible-grown silicon. For 1- and 10-ohm-cm float-zone material that was oxidized during processing, the introduction rates for this trap were comparable to those for crucible-grown silicon. This behavior indicates that the minority carrier trap involves oxygen and that it may be due to a boron-oxygen complex. The majority carrier trap seen in heavily doped, float-zone silicon may also involve boron but not oxygen. Observed trap concentrations suggest that oxygen content in the regions examined by DLTS is affected by processing techniques. Other differences were observed in defect production and annealing behavior of electron-irradiated, float-zone and crucible-grown silicon.

Deangelis, H. M.; Drevinsky, P. J.

1984-01-01

59

Modeling of Laser Vaporization and Plume Chemistry in a Boron Nitride Nanotube Production Rig  

NASA Technical Reports Server (NTRS)

Flow in a pressurized, vapor condensation (PVC) boron nitride nanotube (BNNT) production rig is modeled. A laser provides a thermal energy source to the tip of a boron ber bundle in a high pressure nitrogen chamber causing a plume of boron-rich gas to rise. The buoyancy driven flow is modeled as a mixture of thermally perfect gases (B, B2, N, N2, BN) in either thermochemical equilibrium or chemical nonequilibrium assuming steady-state melt and vaporization from a 1 mm radius spot at the axis of an axisymmetric chamber. The simulation is intended to define the macroscopic thermochemical environment from which boron-rich species, including nanotubes, condense out of the plume. Simulations indicate a high temperature environment (T > 4400K) for elevated pressures within 1 mm of the surface sufficient to dissociate molecular nitrogen and form BN at the base of the plume. Modifications to Program LAURA, a finite-volume based solver for hypersonic flows including coupled radiation and ablation, are described to enable this simulation. Simulations indicate that high pressure synthesis conditions enable formation of BN vapor in the plume that may serve to enhance formation of exceptionally long nanotubes in the PVC process.

Gnoffo, Peter A.; Fay, Catharine C.

2012-01-01

60

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

61

Production of medical radioisotopes in the ORNL high flux isotope reactor (HFIR) for cancer treatment and arterial restenosis therapy after PICA  

Microsoft Academic Search

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. First beginning operation\\u000a in 1965, the high thermal neutron flux (2.51015 neutrons\\/cm2\\/sec at 85 MW) and versatile target irradiation and handling facilities provide the opportunity for production of a wide variety\\u000a of neutron-rich

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

1999-01-01

62

The Spallagenic Production Rates of Lithium, Beryllium and Boron  

Microsoft Academic Search

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

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

2000-01-01

63

Annual Technical Progress Report of Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2006 Through September 30, 2007.  

National Technical Information Service (NTIS)

The Office of Radioisotope 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 t...

J. F. King

2008-01-01

64

The Spallagenic Production Rates of Lithium, Beryllium and Boron  

Microsoft Academic Search

We calculate the production rates of Li6, Li7, Be9, B10 and B11 via\\u000aspallation of Carbon, Nitrogen and Oxygen nuclei by protons and alpha-particles\\u000aand by alpha-alpha fusion reactions. We include recent measurements of the\\u000across sections of alpha-alpha fusion reactions and find that the computations\\u000ayield rates of Li6 and Li7 production that are nearly a factor of two

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

2000-01-01

65

Product and by-product formation in laboratory studies on disinfection electrolysis of water using boron-doped diamond anodes  

Microsoft Academic Search

Boron-doped diamond (BDD) electrodes were studied with respect to the formation of inorganic by-products in water electrolysis. Experiments in non-divided cells were performed with systems containing sulphate, chloride, chlorite, chlorate and nitrate ions. Discontinuous experiments in thermostated cells with rotating disk diamond anodes and expanded mesh IrO2 cathodes were carried out at 20C. Current density was varied between 50 and

M. E. Henry Bergmann; Johanna Rollin

2007-01-01

66

Lithium, beryllium, and boron production in core-collapse supernovae  

NASA Astrophysics Data System (ADS)

Type Ic supernova (SN Ic) is the gravitational collapse of a massive star without H and He layers. It propels several solar masses of material to the typical velocity of 10,000 km/s, a very small fraction of the ejecta nearly to the speed of light. We investigate SNe Ic as production sites for the light elements Li, Be, and B, via the neutrino-process and spallations. As massive stars collapse, neutrinos are emitted in large numbers from the central remnants. Some of the neutrinos interact with nuclei in the exploding materials and mainly 7Li and 11B are produced. Subsequently, the ejected materials with very high energy impinge on the interstellar/circumstellar matter and spall into light elements. We find that the ?-process in the current SN Ic model produces a significant amount of 11B, consistent with observations if combined with B isotopes from the following spallation production.

Nakamura, Ko; Yoshida, Takashi; Shigeyama, Toshikazu; Kajino, Toshitaka

2010-04-01

67

Discussion of possible content of an IAEA (International Atomic Energy Agency) handbook\\/computer file for ''Data for Medical Radioisotope Production''  

Microsoft Academic Search

Several possible approaches will be put forward in order to stimulate discussion and seek consensus on the relative emphasis and format of a proposed IAEA handbook and computer file for ''Data for Medical Radioisotope Production.'' An outline for possible chapters for non-nuclear physicists will be presented describing low, medium, and high energy reactions induced by light projectiles (e.g., n,p,..cap alpha..),

Blann

1987-01-01

68

Semi-Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2001 Through March 31, 2002  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. For the Cassini Mission, for example, ORNL was involved in the production of carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS). This report has been divided into three sections to reflect program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2002. The first section deals primarily with maintenance of the capability to produce flight quality (FQ) CBCF insulator sets, iridium alloy blanks and foil, and CVS. In all three cases, production maintenance is assured by the manufacture of limited quantities of FQ components. The second section deals with several technology activities to improve the manufacturing processes, characterize materials, or to develop technologies for new radioisotope power systems. The last section is dedicated to studies related to the production of {sup 238}Pu.

J. P. Moore, JPM

2002-05-22

69

Semi-Annual Technical Progress Report of the Radioisotope Power System Materials Production and Technology Program Tasks for September 2000 through March 2001  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. For the Cassini Mission, for example, ORNL was involved in the production of carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) and weld shields (WS). This report has been divided into three sections to reflect program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2001. The first section deals primarily with maintenance of the capability to produce flight quality (FQ) CBCF insulator sets, iridium alloy blanks and foil, CVS, and WS. In all three cases, production maintenance is assured by the manufacture of limited quantities of FQ components. The second section deals with several technology activities to improve the manufacturing processes, characterize materials. or to develop technologies for new radioisotope power systems. The last section is dedicated to studies related to the production of {sup 238}Pu.

Moore, J.P.

2001-05-22

70

Semi-Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for April 1, 2002 Through September 20, 2002  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. For the Cassini Mission, for example, ORNL was involved in the production of carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS). This report has been divided into three sections to reflect program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2002. The first section deals primarily with maintenance of the capability to produce flight quality (FQ) CBCF insulator sets, iridium alloy blanks and foil, and CVS. In all three cases, production maintenance is assured by the manufacture of limited quantities of FQ components. The second section deals with several technology activities to improve the manufacturing processes, characterize materials, or to develop technologies for new radioisotope power systems. The last section is dedicated to studies related to the production of {sup 238}Pu.

Moore, J.P.

2002-12-03

71

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2002 Through September 30, 2003  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. For the Cassini Mission, for example, ORNL was involved in the production of carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS). This report has been divided into three sections to reflect program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2003. The first section deals primarily with maintenance of the capability to produce flight quality (FQ) CBCF insulator sets, iridium alloy blanks and foil, and CVS. In all three cases, production maintenance is assured by the manufacture of limited quantities of FQ components. The second section deals with several technology activities to improve the manufacturing processes, characterize materials, or to develop technologies for new radioisotope power systems. The last section is dedicated to studies related to the production of {sup 238}Pu.

King, J.F.

2004-05-18

72

Production of Lithium, Beryllium and Boron in Supernova Ejecta  

NASA Astrophysics Data System (ADS)

We model the nucleosynthesis of light elements (Li,Be,B) by spallation of C,N,O targets by accelerated H,He in expanding supernova ejecta. Recent observations of metal-poor halo dwarfs indicate that these light element abundance increases linearly with metalicity, i.e. the ratio of these elements to iron is constant. The model of formation of these elements in interstellar medium where spallation takes place by galactic cosmic rays colliding with interstellar matter would not give a linear dependence of spallation products with iron abundance. We investigate the scenario of formation of these elements in expanding supernova where spallation would take place in an unmixed medium of supernova ejecta, which would give the observed linear dependence. Calculations will be presented on energetics of this scenario and abundances and ratios of the isotopes of Li,Be,B.

Majmudar, Deepa

1995-12-01

73

78 FR 1848 - Plutonium-238 Production for Radioisotope Power Systems for National Aeronautics and Space...  

Federal Register 2010, 2011, 2012, 2013

...of Pu-238 reserved for U.S. space missions was likely to be depleted...production of Pu-238 to support U.S. space exploration and national security missions...from Russia to meet near-term space mission requirements while...

2013-01-09

74

Feasibility study for production of I-131 radioisotope using MNSR research reactor.  

PubMed

A feasibility study for (131)I production using a Low Power Research Reactor was conducted to predict the yield of (131)I by cyclic activation technique. A maximum activity of 5.1GBq was achieved through simulation using FORTRAN 90, for an irradiation of 6h. But experimentally only 4h irradiation could be done, which resulted in an activity of 4.010(5)Bq. The discrepancy in the activities was due to the fact that beta decays released during the process could not be considered. PMID:21900016

Elom Achoribo, A S; Akaho, Edward H K; Nyarko, Benjamin J B; Osae Shiloh, K D; Odame Duodu, Godfred; Gibrilla, Abass

2012-01-01

75

LANL Activities Supporting Electron Accelerator Production of 99Mo for NorthStar Medical Radioisotopes, LLC  

SciTech Connect

Summary of LANL FY12 Activities are: (1) Preparation, performance, and data analysis for the FY12 accelerator tests at ANL - (a) LANL designed and installed a closed-loop helium target cooling system at ANL for the FY12 accelerator tests, (b) Thermal test was performed on March 27, (c) 24 h production test to follow the accelerator upgrade at ANL; (2) Local target shielding design and OTR/IR recommendations - (a) Target dose rate and activation products were calculated with MCNPX, (b) {sup 206}Pb({gamma},2n){sup 204m}Pb vs {sup 204g}Pb branching ratio unpublished, will measure using the LANL microtron, (c) OTR system nearing final configuration, (d) IR prototype system demonstrated during the recent thermal test at ANL; (3) Target housing lifetime estimation - Target housing material specifications and design to be finalized following the thermal test, lifetime not believed to be an issue; and (4) Target cooling system reliability - Long duration system characterizations will begin following the thermal test.

Dale, Gregory E. [Los Alamos National Laboratory; Kelsey, Charles T. IV [Los Alamos National Laboratory; Woloshun, Keith A. [Los Alamos National Laboratory; Holloway, Michael A. [Los Alamos National Laboratory; Olivas, Eric R. [Los Alamos National Laboratory; Dalmas, Dale A. [Los Alamos National Laboratory; Romero, Frank P. [Los Alamos National Laboratory; Hurtle, Kenneth P. [Los Alamos National Laboratory

2012-07-11

76

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Programs Tasks for October 1, 2005, through September 30, 2006  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. For the Cassini Mission, ORNL produced carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) used in the generators. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. This report reflects program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2006. 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 radioisotope power systems.

None

2006-09-30

77

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Tasks for October 1, 2004 through September 30, 2005  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. For the Cassini Mission, ORNL produced carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) used in the generators. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. This report reflects program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2005. 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 radioisotope power systems.

None listed

2006-08-03

78

ANNUAL TECHNICAL PROGRESS REPORT OF RADIOISOTOPE POWER SYSTEM MATERIALS PRODUCTION AND TECHNOLOGY PROGRAM TASKS FOR OCTOBER 1, 2004, THROUGH SEPTEMBER 30, 2005  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. For the Cassini Mission, ORNL produced carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) used in the generators. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. This report reflects program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2005. 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 radioisotope power systems.

None

2005-09-30

79

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2004 Through September 30, 2005  

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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet Saturn. For the Cassini Mission, ORNL produced carbon-bonded carbon fiber (CBCF) insulator sets, iridium alloy blanks and foil, and clad vent sets (CVS) used in the generators. The Oak Ridge National Laboratory (ORNL) has been involved in developing materials and technology and producing components for the DOE for more than three decades. This report reflects program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2005. 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 radioisotope power systems.

King, James F [ORNL

2006-06-01

80

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

NASA Astrophysics Data System (ADS)

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

Wiley, Charles Schenck

81

Development of the Radioisotope Program in Taiwan, ROC.  

National Technical Information Service (NTIS)

Since the establishment of the radioisotope laboratory in 1978, INER has fully applied its 40 MWt Taiwan Research Reactor for the production of radioisotopes. Today INER is almost the sole supplier of radioisotopes in the Republic of China, and is ready f...

T. K. Lin, J. P. Chien

1983-01-01

82

Production of Lithium, Beryllium and Boron and Analysis of Nuclear Gamma-Ray Line Emission in Active Star Forming Regions  

Microsoft Academic Search

A model for the formation of the elements Lithium, Beryllium and Boron is presented. The main formation mechanism for these elements has been known to be a process called nuclear spallation. Spallation between protons or alpha particles and the Carbon, Nitrogen and Oxygen nuclei result in the production of the isotopes of Li, Be and B. The originally proposed site

Deepa Paresh Majmudar

1998-01-01

83

Annual Technical Progress Report of the Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2008 through September 30, 2009.  

National Technical Information Service (NTIS)

The Office of Space and Defense Power Systems of the U. S. Department of Energy (DOE) provides Radioisotope Power Systems (RPS) for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators (RTG) w...

J. F. King

2010-01-01

84

Annual Technical Progress Report of Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2007 through September 30, 2008.  

National Technical Information Service (NTIS)

The Office of Radioisotope Power Systems (RPS) of the Department of Energy (DOE) provides RPS for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators were supplied by the DOE to the National ...

J. F. King

2009-01-01

85

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2004 through September 30, 2005.  

National Technical Information Service (NTIS)

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...

2006-01-01

86

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2004 Through September 30, 2005.  

National Technical Information Service (NTIS)

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...

J. F. King

2006-01-01

87

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2002 Through September 30, 2003.  

National Technical Information Service (NTIS)

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...

2004-01-01

88

Semi-Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Task for April 1, 2002 through September 30, 2002.  

National Technical Information Service (NTIS)

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...

2004-01-01

89

Annual Technical Progress Report of Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2006 Through September 30, 2007  

Microsoft Academic Search

The Office of Radioisotope 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 for deep space missions including the Cassini Mission launched in October of 1997 to study the planet

James F

2008-01-01

90

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

91

Annual Technical Progress Report of the Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2008 through September 30, 2009  

SciTech Connect

The Office of Space and Defense Power Systems of the U. S. Department of Energy (DOE) provides Radioisotope Power Systems (RPS) for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators (RTG) 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. ORNL has been involved in developing materials and technology and producing components for the DOE for more than three decades. This report reflects program guidance from the Office of Space and Defense Power Systems for fiscal year (FY) 2009. 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.

King, James F [ORNL

2010-05-01

92

Green approachmulticomponent production of boroncontaining hantzsch and biginelli esters.  

PubMed

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

Martnez, Joel; Romero-Vega, Stephany; Abeja-Cruz, Rita; Alvarez-Toledano, Cecilio; Miranda, Ren

2013-01-01

93

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

94

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

Microsoft Academic Search

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

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

1978-01-01

95

Arabidopsis boron transporter for xylem loading  

Microsoft Academic Search

Boron deficiency hampers the productivity of 132 crops in more than 80 countries. Boron is essential in higher plants primarily for maintaining the integrity of cell walls and is also beneficial and might be essential in animals and in yeast. Understanding the molecular mechanism(s) of boron transport is crucial for alleviating boron deficiency. Here we describe the molecular identification of

Junpei Takano; Kyotaro Noguchi; Miho Yasumori; Masaharu Kobayashi; Zofia Gajdos; Kyoko Miwa; Hiroaki Hayashi; Tadakatsu Yoneyama; Toru Fujiwara

2002-01-01

96

Annual Technical Progress Report of Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2007 Through September 30,2008  

Microsoft Academic Search

The Office of Radioisotope Power Systems (RPS) of the Department of Energy (DOE) provides 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.

James F

2009-01-01

97

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2002 Through September 30, 2003  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

2004-01-01

98

ANNUAL TECHNICAL PROGRESS REPORT OF RADIOISOTOPE POWER SYSTEM MATERIALS PRODUCTION AND TECHNOLOGY PROGRAM TASKS FOR OCTOBER 1, 2005 THROUGH SEPTEMBER 30, 2006  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

James F

2007-01-01

99

Semi-Annual Technical Progress Report of the Radioisotope Power System Materials Production and Technology Program Tasks for September 2000 through March 2001  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

2001-01-01

100

Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2004 Through September 30, 2005  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

James F

2006-01-01

101

Semi-Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for October 1, 2001 Through March 31, 2002  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

J. P. Moore

2002-01-01

102

Semi-Annual Technical Progress Report of Radioisotope Power System Materials Production and Technology Program Tasks for April 1, 2002 Through September 20, 2002  

Microsoft Academic Search

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 for deep space missions including the Cassini Mission launched in October of 1997 to study

2002-01-01

103

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

Microsoft Academic Search

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

James F

2012-01-01

104

Annual Technical Progress Report of the Radioisotope Power Systems Materials Production and Technology Program Tasks for October 1, 2008 through September 30, 2009  

Microsoft Academic Search

The Office of Space and Defense Power Systems of the U. S. Department of Energy (DOE) provides Radioisotope Power Systems (RPS) for applications where conventional power systems are not feasible. For example, radioisotope thermoelectric generators (RTG) were supplied by the DOE to the National Aeronautics and Space Administration (NASA) for deep space missions including the Cassini Mission launched in October

James F

2010-01-01

105

Ignition and combustion of boron particles in hydrogen/oxygen combustion products at 30 to 150 atmospheres  

NASA Astrophysics Data System (ADS)

The ignition and combustion of crystalline boron particles is studied at high pressures and temperatures in the combustion products of nitrogen diluted premixed hydrogen/oxygen mixtures at nearly constant pressure conditions. Particle ignition and combustion are monitored optically by measuring combusting particle emissions. The methodology is used to measure the ignition delay and combustion times of 24 micron boron particles over a range of pressures (30-150 atm), temperatures (2440, 2630, 2830 K), excess Osb2 concentrations (5, 11, 20%), and with two proposed ignition enhancers (COsb2, HF). Several particles sizes are investigated at one condition (12, 24, 48 mum) to determine particle scaling laws. Although boron has been observed previously to exhibit a two-stage ignition process at lower pressures and temperatures, only a single continuously increasing luminous stage is observed here. Boron particle ignition delays for 24 mum are of the order of 1-2 milliseconds, and are reduced with increased pressure, decreased particle size, and increased temperature but increase with increasing ambient oxygen concentrations. Combustion times for 24 mum particles are between 1-5 msec, but drop significantly between 2440 K and 2600 K, decreasing by a factor of at least two, and are reduced with increased pressure. Both ignition delays and combustion times obey a dsp1-scaling law (linear) as particle diameter increases, suggesting processes are kinetics-controlled. The two tested ignition-enhancing agents show no signs of accelerated ignition and 5% HF was found to increase ignition delays. Measured ignition delays are compared to predictions from two ignition models showing generally good agreement in the average sense when convective heating is handled appropriately; however, the models under-predict the measured decrease in boron particle ignition delays with increasing pressure and do not predict the sharp decrease in ignition and combustion times as temperature is increased between 2440 K and 2600 K. The results of this study demonstrate that boron particle lifetimes at elevated pressures are sufficiently short to make these particles suitable for additives to propellants and that smaller 1-10 mum sized particles, which have still shorter lifetimes, may be appropriate for addition to explosives.

Foelsche, Robert Oliver

106

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

107

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

108

Spark Plasma Sintering of simulated radioisotope materials within tungsten cermets  

NASA Astrophysics Data System (ADS)

A Spark Plasma Sintering (SPS) furnace was used to produce ceramic-metallic sinters (cermets) containing a simulated loading of radioisotope materials. CeO 2 was used to simulate loadings of PuO 2, UO 2 or AmO 2 within tungsten-based cermets due to the similar kinetic properties of these materials, in particular the respective melting points and Gibbs free energies. The work presented demonstrates the capability and suitability of the SPS process for the production of radioisotope encapsulates for nuclear fuels and other applications (including waste disposal and radioisotope power and heat source fabrication) where the mechanical capture of radioisotope materials is required.

O'Brien, R. C.; Ambrosi, R. M.; Bannister, N. P.; Howe, S. D.; Atkinson, H. V.

2009-08-01

109

Effect of potassium, sulfur, boron, and molybdenum fertilization on alfalfa production and herbage macronutrient contents  

Microsoft Academic Search

An established two?year?old stand of Apollo alfalfa (Medicago saliva L.) was used to determine the alfalfa yield and macronutrient contents response to potassium (K), sulfur (S), boron (B), and molybdenum (Mo) fertilization under a high yield environment. A split, split block field design was used with nine micronutrient treatments (0, 50, and 100 g Mo ha and 0, 1, and

Khorshid Razmjoo; Paul R. Henderlong

1997-01-01

110

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

111

The Evolution of Galactic Boron and the Production Site of the Light Elements  

NASA Astrophysics Data System (ADS)

The Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) has been used to obtain spectra of the 2500 region in eight stars with metallicities ranging from [Fe/H] = -0.4 to -3.0, including the most metal-poor star ever observed for boron. Spectrum synthesis utilizing latest Kurucz model atmospheres has been used to determine the B abundance for each star, with particular attention paid to the errors of each point, to permit judgment of the quality of the fit of models of Galactic chemical evolution. Previous observations were combined with new ones, bringing the number of stars analyzed to 11. A straight line of slope ~1 gives an excellent fit to a plot4 of log ?(BLTE) versus [Fe/H], and if NLTE B abundances are used, the slope is ~0.7. Plotting B versus [O/H] rather than [Fe/H] increases the slope of either plot by about 0.2. The observed relation suggests that the production of light elements such as B and Be is directly related to the production of heavier elements. Our data do not show a change in slope between halo and disk metallicities, but the number of stars near the disk-halo transition is small, and a modest change is not precluded. The NLTE B/Be ratio is typically ~15 throughout the lifetime of the Galaxy, a ratio naturally produced by cosmic-ray (CR) spallation. Our data support a model in which most light-element production comes from low-energy CR spallation of C and O nuclei onto protons and ?-particles, probably in the vicinity of massive supernovae in star-forming regions. Until recently, most models have emphasized light-element production in the general ISM from the spallation of high-energy protons and ?-particles onto CNO nuclei. Especially during the Galaxy's early history, when the metallicity of the ISM was low, the spallation of protons and ?-particles onto CNO nuclei cannot account for as much B as we observe, unless the CR flux was sufficiently high for compensation. The observed relation also constrains any direct production of B by the ?-process in supernovae to be at most a small part of total B production. It is possible that the gamma rays recently detected from the Orion Nebula region are the signature of spallation by energetic C and O nuclei. Nevertheless, B, Be, and Fe data alone give the strongest evidence of the importance of spallation by C and O for producing light elements. This research was based on observations made by the NASA/ESA Hubble Space Telescope through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Duncan, D. K.; Primas, F.; Rebull, L. M.; Boesgaard, A. M.; Deliyannis, Constantine P.; Hobbs, L. M.; King, J. R.; Ryan, S. G.

1997-10-01

112

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

113

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

114

Radioisotope Power Systems  

NSDL National Science Digital Library

This NASA webpage discusses radioisotope power systems in past, present, and future space missions. It also discusses some of the successes that the radioisotopes have had on satellite missions. The webpage also includes a timeline of past missions and their accomplishments. This site also has links to other areas of the NASA Solar System page. In these links, there are videos that explain some of the instrumentation, and some of the major accomplishments of various missions. The site includes an interactive 3-D simulation that allows users go explore the solar system and learn about past satellite missions.

Administration, National A.

2012-06-19

115

Cosmogenic radioisotopes on LDEF surfaces  

NASA Technical Reports Server (NTRS)

The radioisotope Be-7 was discovered in early 1990 on the front surface, and the front surface only, of the LDEF. A working hypothesis is that the isotope, which is known to be mainly produced in the stratosphere by spallation of nitrogen and oxygen nuclei with cosmic ray protons or secondary neutrons, diffuses upward and is absorbed onto metal surfaces of spacecraft. The upward transport must be rapid, that is, its characteristic time scale is similar to, or shorter than, the 53 day half-life of the isotope. It is probably by analogy with meteoritic metal atmospheric chemistry, that the form of the Be at a few 100 km altitude is as the positive ion Be(+) which is efficiently incorporated into the ionic lattice of oxides, such as Al2O3, Cr2O3, Fe2O3, etc., naturally occurring on surfaces of Al and stainless steel. Other radioisotopes of Be, Cl, and C are also produced in the atmosphere, and a search was begun to discover these. Of interest are Be-10 and C-14 for which the production cross sections are well known. The method of analysis is accelerator mass spectrometry. Samples from LDEF clamp plates are being chemically extracted, purified, and prepared for an accelerator run.

Gregory, J. C.; Albrecht, A.; Herzog, G.; Klein, J.; Middleton, R.

1992-01-01

116

Boronizing protects metals against wear  

SciTech Connect

Boronizing is a thermochemical surface treatment that involves diffusion of boron into a base metal at a high temperature. The resulting metallic boride provides high hardness and resistance to acid corrosion, and lengthens service life by a factor of three to ten. Boronizing fills a gap between conventional surface treatments and the more exotic chemical and physical vapor deposition. In a number of applications, boronizing has replaced such processes as carburizing, nitriding, and nitrocarburizing. It has even replaced hard chrome plating in some cases, while achieving similar service life improvements. Boron can be uniformly applied to irregular surfaces, and can be applied to specific areas of a surface. It is also suitable for high-volume production applications, as first demonstrated in the European automotive industry. This article describes the boronizing process, provides material selection/preparation criteria, and lists industrial applications.

Stewart, K. [Lindberg Heat Treating Co., Rochester, NY (United States)

1997-03-01

117

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

118

Radioisotopic method development for express determination of working mixtures proppant concentration used with the hydraulic break of gas and oil production beds  

Microsoft Academic Search

This paper describes the RIPC-01 radioisotopic meter for the determination of the working mixture proppant concentration used in the hydraulic break to increase oil and gas bore output. The method involves simultaneously measuring the helium density at the input into the unit for the working mixture preparation and the working mixture at the output from the unit for the working

O. T. Nurgaliev; V. K. Kuleshov; Yu. A. Volchenko; M. S. Suhkanov

2003-01-01

119

Small Radioisotope Power System at NASA Glenn Research Center.  

National Technical Information Service (NTIS)

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 Lu...

A. Shamkovich D. Duven D. P. Frankford D. W. Meer G. M. Dugala H. Ambrose M. Fraeman

2012-01-01

120

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

121

Radioisotope study of salivary glands  

SciTech Connect

The book discusses the use of radioisotope methods in the diagnosis of salivary gland diseases. Anatomical and physiological features of the salivary gland are summarized and radiotracer deposition processes are described. Clinical applications of scintigraphy are detailed. The degree of functional impairment due to various inflammatory diseases is contrasted by means of semiquantitative computerized methods with follow-up therapeutic results. Post-irradiatory involvement and possible functional recovery of salivary glands are also considered. The contents discussed are: Salivary Gland Physiology and Radioisotope Uptake. Radioisotope Study of Salivary Glands. Radioisotope Studies Under Normal Conditions. Survey of Radiographic Methods. Dosimetric Assessment. Conclusions and Index.

De Rossi, G.

1987-01-01

122

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

123

Radioisotopes as Political Instruments, 1946-1953  

PubMed Central

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 countrys atomic monopoly at all costs, linked to American anti-Communism. This essay examines the various ways in which radioisotopes were used as political instrumentsboth by the U.S. federal government in world affairs, and by critics of the civilian control of atomic energyin the early Cold War.

Creager, Angela N. H.

2009-01-01

124

Waste minimization in the Los Alamos Medical Radioisotope Program  

SciTech Connect

Since the mid-1970s the Los Alamos Medical Radioisotope Program has been irradiating target materials to produce and recover radioisotopes for applications in medicine, environmental science, biology, physics, materials research, and other disciplines where radiotracers find utility. By necessity, the chemical processing of targets and the isolation of radioisotopes generates radioactive waste materials. Recent years have brought pressure to discontinue the use of hazardous materials and to minimize radioactive waste volumes. Substantial waste reduction measures have been introduced at the irradiation facility, in processing approaches, and even in the ways the product isotopes are supplied to users.

Taylor, W.A.; Jamriska, D.J.; Hamilton, V.T.; Heaton, R.C.; Phillips, D.R.; Staroski, R.C.; Garcia, J.B.; Garcia, J.G.; Ott, M.A.

1994-04-01

125

Alternative Radioisotopes for Heat and Power Sources  

NASA Astrophysics Data System (ADS)

Production of 238Pu requires considerable facilities including a nuclear reactor and reprocessing plants that are very expensive to build and operate. Thus, a more economical alternative is very attractive to the industry. There are many alternative radioisotopes that exist but few that satisfy the criteria of performance, availability and cost to produce. Any alternative to 238Pu must exist in a chemical form that is compatible with the materials required to safely encapsulate the heat source at the high temperatures of operation and potential launch failure scenarios. The chemical form must also have suitable thermal properties to ensure maximum energy conversion efficiencies when integrated into radioisotope thermoelectric generators over the required mission durations. In addition, the radiation dose must be low enough for operators during production and not so prohibitive that excessive shielding mass is required on the space craft. This paper will focus on the preferred European alternative of 241Am, and the issues that will need to be addressed.

Tinsley, T.; Sarsfield, M.; Rice, T.

126

Cosmic ray models for early galactic lithium, beryllium, and boron production  

Microsoft Academic Search

To better understand 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 isotropic production to the cosmic ray pathlength magnitude and energy dependence, source spectrum spallation kinematics, and cross section uncertainties is studied.

Brian D. Fields; Keith A. Olive; David N. Schramm

1994-01-01

127

Determination of a small amount of boron carbide in wurtzitelike boron nitride  

Microsoft Academic Search

The authors expound a method for analyzing Wurtzitelike boron nitride powders and they apply their method to several production batches. The results show that the proposed method of determining the boron content of the wurtzitelike boron nitride is characterized by a fairly high accuracy and good reproducability of results.

L. E. Pechentkovskaya; T. N. Nazarchuk

1985-01-01

128

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

Microsoft Academic Search

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 structures or in solidification\\/stabilization (S\\/S) technology. Strengths of cured pastes (91 days),

B. Docktor; K. E. Eylands; J. S. Thompson; D. J. Hassett

1995-01-01

129

Cosmic-ray models for early Galactic Lithium, Beryllium, and Boron production  

Microsoft Academic Search

To understand better the early Galactic production of Li, Be, and B by comsmic-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 path length magnitude and energy dependence, source spectrum, spallation kinematics, and cross section uncertainties is studied. Changes in

Brian D. Fields; Keith A. Olive; David N. Schramm

1994-01-01

130

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

Microsoft Academic Search

To understand better the early galactic production of Li, Be, and B by cosmic\\u000aray spallation and fusion reactions, the dependence of these production rates\\u000aon cosmic ray models and model parameters is examined. The sensitivity of\\u000aelemental and isotopic production to the cosmic ray pathlength magnitude and\\u000aenergy dependence, source spectrum, spallation kinematics, and cross section\\u000auncertainties is studied.

Brian D. Fields; Keith A. Olive; David N. Schramm

1994-01-01

131

Short-lived fission product measurements from >0.1 MeV neutron-induced fission using boron carbide.  

SciTech Connect

A boron carbide shield was designed, custom fabricated, and used to create a fast fission energy neutron spectrum. The fissionable isotopes 233, 235, 238U, 237Np, and 239Pu were separately placed inside of this shield and irradiated under pulsed conditions at the Washington State University 1 MW TRIGA reactor. A unique set of fission product gamma spectra were collected at short times (4 minutes to 1 week) post-fission. Gamma spectra were collected on single-crystal high purity germanium detectors and on Pacific Northwest National Laboratory's (PNNL's) Direct Simultaneous Measurement (DSM) system composed of HPGe detectors connected in coincidence. This work defines the experimental methods used to produce and collect the gamma data, and demonstrates the validity of the measurements. It is important to fully document this information so the data can be used with high confidence for the advancement of nuclear science and non-proliferation applications. The gamma spectra collected in these and other experiments will be made publicly available at https://spcollab.pnl.gov/sites/gammadata or via the link at http://rdnsgroup.pnl.gov. A revised version of this publication will be posted with the data to make the experimental details available to those using the data.

Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce D.; Friese, Judah I.; Kephart, Rosara F.; Kephart, Jeremy D.

2012-02-01

132

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

133

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

134

Cosmic ray models for early galactic lithium, beryllium, and boron production  

NASA Technical Reports Server (NTRS)

To better understand 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 isotropic 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 naive 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.

Fields, Brian D.; Olive, Keith A.; Schramm, David N.

1994-01-01

135

Tezisy dokladov 1-oj Respublikanskoj konferentsii 'Radioizotopy i ikh ispol'zovanie. (Abstracts of the 1st Republican conference on radioisotopes and their applications).  

National Technical Information Service (NTIS)

The first Republican Conference on Radioisotopes an their Applications was held on 24-26 October, 1995 in Tashkent. The specialists discussed various aspects of radioisotope production and their applications in the fields of industry, agriculture, life sc...

1995-01-01

136

Production of Lithium, Beryllium, and Boron by Hypernovae and the Possible Hypernova-Gamma-Ray Burst Connection  

NASA Astrophysics Data System (ADS)

We investigate a possible nucleosynthetic signature of highly energetic explosions of C-O cores (``hypernovae'' [HNe]) that 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 that 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 much higher than those produced by similar (direct) means in normal Type II supernovae (SNe) and are higher than the commonly used ones arising from shock wave acceleration induced by Type II supernova explosions. To avoid overproduction of these elements in our Galaxy, hypernovae should be rare events, with <~310-2 hypernovae per supernova, assuming a constant HN/SN ratio over time; this result also implies that the HN production of Be is only a fraction of other sources, e.g., superbubbles. Our limit to the HN/SN ratio is in good agreement with that of long-duration GRBs if we assume that the gamma-ray emission is focussed in a solid angle ? so that <(?/4?)-1><~3104. 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 with massive pregalactic stars (Population III), they would produce an LiBeB pre-enrichment in protogalactic gas, which could show up as a plateau in the lowest metallicities of the Be-Fe relation in halo stars.

Fields, Brian D.; Daigne, Frdric; Cass, Michel; Vangioni-Flam, Elisabeth

2002-12-01

137

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

138

Inhomogeneous big bang nucleosynthesis: Upper limit on ?b and production of lithium, beryllium, and boron  

NASA Astrophysics Data System (ADS)

We examine the big bang nucleosynthesis (BBN) process in the presence of small-scale baryon inhomogeneities. Primordial abundance yields for D, 4He, 6Li, 7Li, 9Be, and 11B are computed for wide ranges of parameters characterizing the inhomogeneities taking account of all relevant diffusive and hydrodynamic processes. These calculations may be of interest due to (a) recent observations of the anisotropies in the cosmic microwave background radiation favoring slightly larger baryonic contribution to the critical density, ?b, than allowed by a standard BBN scenario and (b) new observational determinations of 6Li and 9Be in metal-poor halo stars. We find considerable parameter space in which production of D and 4He is in agreement with observational constraints even for ?bh2 a factor 2 or 3 larger than the ?b inferred from standard BBN. Nevertheless, in this parameter space synthesis of 7Li in excess of the inferred 7Li abundance on the Spite plateau results. Production of 6Li, 9Be, and 11B in inhomogeneous BBN scenarios is still typically well below the abundance of these isotopes observed in the most metal-poor stars to date thus neither confirming nor rejecting inhomogeneous BBN. In an Appendix we summarize results of a reevaluation of baryon diffusion constants entering inhomogeneous BBN calculations.

Jedamzik, Karsten; Rehm, Jan B.

2001-07-01

139

Hollow and Threadlike Nanostructures of Boron Carbide  

Microsoft Academic Search

An original low-temperature method is proposed for the synthesis of boron carbide from simple materials. It made it possible to obtain a powdered product in the form of hollow and threadlike nanostructures. The boron carbide nanotubes are shorter than bundles of nanotubes. The boron carbide nanostructures are grown from vapor-phase reagents at a high-temperature nanocenter, the enhanced reactivity of which

A. I. Kharlamov; N. V. Kirillova; S. N. Kaverina

2003-01-01

140

Production of Lithium, Beryllium and Boron and Analysis of Nuclear Gamma-Ray Line Emission in Active Star Forming Regions  

NASA Astrophysics Data System (ADS)

A model for the formation of the elements Lithium, Beryllium and Boron is presented. The main formation mechanism for these elements has been known to be a process called nuclear spallation. Spallation between protons or alpha particles and the Carbon, Nitrogen and Oxygen nuclei result in the production of the isotopes of Li, Be and B. The originally proposed site for spallation, well-mixed interstellar medium, was found to be inconsistent with the recent observations of linearly varying abundances of Be and B with respect to the metallicity in metal-poor stars. We propose a model for spallation occuring in the unmixed ejecta of supernova as the primary mode of production of the isotopes of Li, Be and B. This scenario was simulated by writing a Monte-Carlo code. The results in terms of the energy required for spallation are feasible compared to the total energy released in a supernova explosion. The calculated isotopic ratios produced were found to generally agree with the observed values. Recent observations of Orion region showing excess flux in 3-7 MeV range, identified as Carbon and Oxygen nuclear deexcitation lines, were followed by models proposing spallation in the vicinity of supernova by collision between energetic C), O nuclei and protons or alpha particles in the surrounding ambient medium. We searched for similar emission from other nearby OB associations, the Cygnus region. Cygnus region contains several large OB associations, including Wolf-Rayet stars, and has a total wind power almost 100 times larger than that in the Orion complex. We present the results from our study of the gamma-ray emission in the 0.75-30 MeV range from the Cygnus region using data from the COMPTEL instrument onboard the Compton Gamma-Ray Observatory (CGRO). In the 3-7 MeV band, where Orion emission is most prominent, we do not find significant emission. We do find significant emission at 1.8 MeV, resulting from the radioactive decay of 26Al. This flux is consistent with the amount predicted from known sources of 26Al in this region.

Majmudar, Deepa Paresh

141

Computation and Analysis of the Global Distribution of the Radioxenon Isotope 133Xe based on Emissions from Nuclear Power Plants and Radioisotope Production Facilities and its Relevance for the Verification of the Nuclear-Test-Ban Treaty  

NASA Astrophysics Data System (ADS)

Monitoring of radioactive noble gases, in particular xenon isotopes, is a crucial element of the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The capability of the noble gas network, which is currently under construction, to detect signals from a nuclear explosion critically depends on the background created by other sources. Therefore, the global distribution of these isotopes based on emissions and transport patterns needs to be understood. A significant xenon background exists in the reactor regions of North America, Europe and Asia. An emission inventory of the four relevant xenon isotopes has recently been created, which specifies source terms for each power plant. As the major emitters of xenon isotopes worldwide, a few medical radioisotope production facilities have been recently identified, in particular the facilities in Chalk River (Canada), Fleurus (Belgium), Pelindaba (South Africa) and Petten (Netherlands). Emissions from these sites are expected to exceed those of the other sources by orders of magnitude. In this study, emphasis is put on 133Xe, which is the most prevalent xenon isotope. First, based on the emissions known, the resulting 133Xe concentration levels at all noble gas stations of the final CTBT verification network were calculated and found to be consistent with observations. Second, it turned out that emissions from the radioisotope facilities can explain a number of observed peaks, meaning that atmospheric transport modelling is an important tool for the categorization of measurements. Third, it became evident that Nuclear Power Plant emissions are more difficult to treat in the models, since their temporal variation is high and not generally reported. Fourth, there are indications that the assumed annual emissions may be underestimated by factors of two to ten, while the general emission patterns seem to be well understood. Finally, it became evident that 133Xe sources mainly influence the sensitivity of the monitoring system in the mid-latitudes, where the network coverage is particularly good.

Wotawa, Gerhard; Becker, Andreas; Kalinowski, Martin; Saey, Paul; Tuma, Matthias; Zhringer, Matthias

2010-05-01

142

Microwave sintering of boron carbide composites  

SciTech Connect

Boron carbide is an important ceramic material because of its high hardness and low specific gravity. it is used for applications involving impact and wear resistance. The disadvantages of boron carbide materials are difficulty in fabrication and sensitivity to brittle fracture. These problems are significantly reduced by production of cermets based on boron carbide and aluminum or aluminum alloys. Microwave heating of boron carbide materials results in ultrarapid heating and high temperatures. Therefore, a finer microstructure is obtained. The objective of this work was to define a technology that would allow the manufacture of boron carbide ceramics having mechanical properties similar to those exhibited by hot-pressed specimens. microwave heating would be used for the densification step. Mixtures of boron carbide and aluminum were considered for this research because aluminum simultaneously acts as a sintering aid and introduces phases that contribute to toughness enhancement.

Ruginets, R.; Fischer, R. (Israel Ceramic and Silicate Inst., Haifa (Israel))

1995-01-01

143

Aspects of Radioisotope Utilization in Clinical Medicine.  

National Technical Information Service (NTIS)

A revision concerning radioisotope use in medicine has been done. The harmlessness and effeciency of radioisotopes are shown. Techniques and advantages of tracers used for brain scintiscanning, lung scintiscanning, liver scintiscanning, spleen scintiscann...

A. F. G. Rocha C. A. de Lima e Forti M. C. Cunha O. de Souza Maciel

1973-01-01

144

RADIOISOTOPES IN ANIMAL AND PLANT BIOLOGY  

Microsoft Academic Search

Chapters are included on the fundamentals of nucleonics and ; radiation, radiation effects and isotope applications, radioisotopes in animal ; physiology and veterinary medicine, and radioisotopes in the plant kingdom. ; (D.E.B.);

O. F. F

1958-01-01

145

High Efficiency Radioisotope Thermophotovoltaic Prototype Generator.  

National Technical Information Service (NTIS)

A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the res...

J. E. Avery J. E. Samaras L. M. Fraas R. Ewell

1995-01-01

146

The all boron carbide diode neutron detector: Comparison with theory  

Microsoft Academic Search

A boron carbide diode detector, fabricated from two different polytypes of semiconducting boron carbide, will detect neutrons in reasonable agreement with theory. Small deviations from the model calculations occur due to the detection efficiencies of the 10B capture products Li plus ? sum signal differing somewhat from expectation in the thin diodes. The performance of the all boron carbide neutron

A. N. Caruso; P. A. Dowben; S. Balkir; Nathan Schemm; Kevin Osberg; R. W. Fairchild; Oscar Barrios Flores; Snjezana Balaz; A. D. Harken; B. W. Robertson; J. I. Brand

2006-01-01

147

Production of Lithium, Beryllium, and Boron by Hypernovae and the Possible Hypernova-Gamma-Ray Burst Connection  

Microsoft Academic Search

We investigate a possible nucleosynthetic signature of highly energetic explosions of C-O cores (``hypernovae'' [HNe]) that 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 that can produce large amounts of the light nuclides lithium, beryllium, and boron (LiBeB). Using

Brian D. Fields; Frdric Daigne; Michel Cass; Elisabeth Vangioni-Flam

2002-01-01

148

Study on the Management of Radioisotope Wastes.  

National Technical Information Service (NTIS)

The amount of annual radwaste generation from the institutional use of radioisotopes based on the estimation of radioisotope imports is made in the present study for 1985-1986 in collaboration with Korea Radioisotope Association Inc. In order to survey an...

G. J. Kim H. H. Park C. H. Kim J. W. Lee T. W. Hwang

1986-01-01

149

Realistic Specific Power Expectations for Advanced Radioisotope Power Systems  

NASA Technical Reports Server (NTRS)

Radioisotope Power Systems (RPS) are being considered for a wide range of future NASA space science and exploration missions. Generally, RPS offer the advantages of high reliability, long life, and predictable power production regardless of operating environment. Previous RPS, in the form of Radioisotope Thermoelectric Generators (RTG), have been used successfully on many NASA missions including Apollo, Viking, Voyager, and Galileo. NASA is currently evaluating design options for the next generation of RPS. Of particular interest is the use of advanced, higher efficiency power conversion to replace the previous thermoelectric devices. Higher efficiency reduces the quantity of radioisotope fuel and potentially improves the RPS specific power (watts per kilogram). Power conversion options include Segmented Thermoelectric (STE), Stirling, Brayton, and Thermophotovoltaic (TPV). This paper offers an analysis of the advanced 100 watt-class RPS options and provides credible projections for specific power. Based on the analysis presented, RPS specific power values greater than 10 W/kg appear unlikely.

Mason, Lee S.

2006-01-01

150

How to Handle Radioisotopes Safely.  

ERIC Educational Resources Information Center

This booklet is one in a series of instructional aids designed for use by elementary and secondary school science teachers. The various units and forms of radioactive materials used by teachers are first considered. Then, the quantities of radioisotopes that a person may possess without a license from the Atomic Energy Commission (AEC) are

Sulcoski, John W.

151

Automatic locking radioisotope camera lock  

Microsoft Academic Search

A radioisotope camera lock for locking the source isotope in a safe, shielded position in the camera when not in use is described. The lock prevents the source isotope from being moved to an operative position outside of the camera, unless intentionally released by a key and reverse movement of source pigtail. A hollow lock casing is secured to and

Rosauer

1976-01-01

152

Boron nitride nanotubes  

DOEpatents

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. (Newport News, VA); Jordan, Kevin (Newport News, VA); Park, Cheol (Yorktown, VA)

2012-06-06

153

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

154

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

155

Reactivity of boron fullerenes  

Microsoft Academic Search

The properties of carbon and boron fullerenes are compared, and similarities and distinctions are pointed out. The ionization\\u000a potentials and electron affinities of boron nanoparticles are estimated, and the binding energy for these systems is calculated.

S. P. Ionov; G. V. Ionova; N. T. Kuznetsov

2011-01-01

156

[Diagnosis of gastroesophageal reflux by radioisotopic techniques].  

PubMed

We evaluated 148 patients (mean age 45 years) with clinically evident gastroesophageal reflux. A radioisotopic test with 99mTc sulphur-colloid was performed in all; endoscopy in 146, biopsy in 24, acid reflux test and manometric evaluation in 141 and radiologic studies in 85. Sensitivity of the different techniques was: radioisotopes 92%, radiology 87%, acid reflux test 84%; endoscopy 63% and manometric studies 61%. Severity of reflux and esophagitis was adequately predicted from radioisotopic evaluation. We conclude that this radioisotopic test is highly reliable for the diagnosis of gastroesophageal reflux. PMID:2519376

Csendes, A; Gonzlez, P; Olea, E; Orellana, P; Papapietro, K; Cortes, C; Diaz, J C; Braghetto, I; Lillo, R; Humeres, P

1989-12-01

157

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

SciTech Connect

In this study, production rates of {sup 125,123}Xe and {sup 133,131,129,128}Ba medical isotopes produced by {sup 127}I(p, 3n){sup 125}Xe, {sup 127}I(p, 5n){sup 123}Xe, {sup 133}Cs(p, n){sup 133mg}Ba, {sup 133}Cs(p, 3n){sup 131mg}Ba, {sup 133}Cs(p, 5n){sup 129}Ba, and {sup 133}Cs(p, 6n){sup 128}Ba 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., E-mail: aaydin@kku.edu.tr; Pekdogan, H. [Kirikkale University, Faculty of Arts and Sciences (Turkey); Tel, E. [Osmaniye Korkut Ata University, Faculty of Arts and Sciences (Turkey); Kaplan, A. [Sueleyman Demirel University, Faculty of Arts and Sciences (Turkey)

2012-03-15

158

Determination of vanillin in commercial food product by adsorptive stripping voltammetry using a boron-doped diamond electrode.  

PubMed

A method for the determination of food additive vanillin was developed by adsorptive stripping voltammetry. Its determination was carried out at the anodically pre-treated boron-doped diamond electrode in aqueous solutions. Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in phosphate buffer, pH 2.5 at +1.14 V (vs. Ag/AgCl) (a pre-concentration step being carried out at open-circuit condition for 60s). A linear calibration graph was obtained in the concentration range of 0.5-15.0 ?g mL(-1) (3.310(-6)-9.810(-5) mol L(-1)) with a detection limit of 0.024 ?g mL(-1) (1.610(-7) mol L(-1)). As an example, the practical applicability of the proposed method was tested for the determination of this flavouring agent in commercial pudding powder of Keshkule (Turkish milk pudding with almond flour). PMID:23870896

Yard?m, Yavuz; Glcan, Mehmet; ?entrk, Zhre

2013-12-01

159

Fabrication Route for the Production of Coplanar, Diamond Insulated, Boron Doped Diamond Macro- and Microelectrodes of any Geometry.  

PubMed

Highly doped, boron doped diamond (BDD) is an electrode material with great potential, but the fabrication of suitable electrodes in a variety of different geometries both at the macro- and microscale, with an insulating material that does not compromise the material properties of the BDD, presents technical challenges. In this Technical Note, a novel solution to this problem is presented, resulting in the fabrication of coplanar macro- and microscale BDD electrodes, insulated by insulating diamond, at the single and multiple, individually addressable level. Using a laser micromachining approach, the required electrode(s) geometry is machined into an insulating diamond substrate, followed by overgrowth of high quality polycrystalline BDD (pBDD) and polishing to reveal approximately nanometer roughness, coplanar all-diamond structures. Electrical contacting is possible using both top and bottom contacts, where the latter are defined using the laser to produce non-diamond-carbon (NDC) in the vicinity of the back side of the BDD. We present the fabrication of individually addressable ring, band, and disk electrodes with minimum, reproducible controlled dimensions of 50 ?m (limited only by the laser system employed). The pBDD grown into the insulating diamond recesses is shown to be free from NDC and possesses excellent electrochemical properties, in terms of extended solvent windows, electrochemical reversibility, and capacitance. PMID:24814161

Joseph, Maxim B; Bitziou, Eleni; Read, Tania L; Meng, Lingcong; Palmer, Nicola L; Mollart, Tim P; Newton, Mark E; Macpherson, Julie V

2014-06-01

160

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.

161

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

162

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

163

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

164

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

165

Radioisotope scanning in osseous sarcoidosis  

SciTech Connect

Technetium-99m (/sup 99m/Tc)-labeled pyrophosphate or diphosphonate compounds and gallium-67 citrate (/sup 67/Ga) are two radionuclide scanning agents that are in widespread use in clinical practice. Technetium-99m pyrophosphate is used extensively for bone scanning to detect metastatic bone disease, benign bone tumors, osteomyelitis, benign hypertrophic osteoarthropathy, and Paget's disease. Only two reports describe abnormal /sup 99m/Tc/ pyrophosphate bone scans in four patients with osseous sarcoidosis. Gallium-67 scans are used primarily to localize neoplastic or inflammatory lesions anywhere in the body. In recent years /sup 67/Ga scans have also been used to detect the presence of both pulmonary and extrapulmonary sarcoidosis, but there are no reports describing abnormal uptake of gallium in patients with osseous sarcoidosis. This report describes experience with radioisotope scanning in two patients with osseous sarcoidosis.

Rohatgi, P.K.

1980-01-01

166

Pressureless sintering of boron carbide phase  

NASA Astrophysics Data System (ADS)

While industrial hot pressing of boron carbide is well known, pressureless sintering is new. Two commercial boron carbide powders are used; the first one was synthetized by an arc-melting technique (B powder) and the second one by a magnesiothermal reaction (A powder). This last one is used after a washing with hydrochloric acid (AH powder) or after a purification by a thermic treatment that we worked out (AP powder). The so achieved powders are characterized. These products are sintered without pressure with an addition of carbon produced by the pyrolysis of a Novolac type phenol-formaldehyde resin (9 %). The achieved densities are about 95% of boron carbide theoretical density. The main characteristics (composition, microstructure) of old isostatic pressed and sintered samples are compared with those of an hot-pressed boron carbide. We give the different ways by which the carbon can act on sintering and why the starting powders behave differently.

Thevenot, F.; Bougoin, M.

1986-04-01

167

Boron-Doped Nanocrystalline Diamond.  

National Technical Information Service (NTIS)

A conductive boron doped nanocrystalline diamond is described. The boron doped diamond has a conductivity which uses the boron in the crystals as a charge carrier. The diamond is particularly useful for electrochemical electrodes in oxidation-reduction re...

G. M. Swain M. Witek P. Sonthalia Y. Show

2004-01-01

168

Serial coupling of RP and zwitterionic hydrophilic interaction LC-MS: suspects screening of diclofenac transformation products by oxidation with a boron-doped diamond electrode.  

PubMed

The presence of pollutants and their transformation products (TPs) in the water system is a big concern because of possible adverse effects on the aquatic environment. Their identification is still a challenge that requires the combination of different chromatographic techniques. In the current research, serial coupling of RPLC and zwitterionic hydrophilic interaction LC with TOF-MS was investigated as a single separation technique for the screening of suspected TPs from electrochemical oxidation of diclofenac using a boron-doped diamond electrode. Diclofenac oxidation was performed in three water matrices in order to study its transformation in different chemical contexts. 47 TPs resulting from similar oxidation methods were selected from the literature. As in most cases standards were not available, an identification procedure based on accurate mass data and chromatographic behavior was proposed. According to this procedure, 11 suspected TPs, previously analyzed by LC, GC, or ion chromatography, were detected in a single injection. The method was proved to be reliable and versatile and it could be efficiently employed as a comprehensive analytical tool for the simultaneous analysis of compounds in a wide polarity range. PMID:23857646

Rajab, Mohamad; Greco, Giorgia; Heim, Carolin; Helmreich, Brigitte; Letzel, Thomas

2013-09-01

169

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

170

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

171

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

172

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

173

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

174

Radioisotope thermoelectric generators for implanted pacemakers  

Microsoft Academic Search

This paper discusses the development and application of long-life lithium batteries and the problems associated with miniature radioisotope thermoelectric generators (RITEG) with service lives of 10 years or longer. On eof the main problems encountered when devising a radioisotope heat source (RHS) for an RITEG is to obtain biomedical ²³⁸PuO with a specific neutron yield of 3.10³-4.10³ (g \\/SUP .\\/

A. A. Pustovalov; V. P. Shapovalov; A. V. Bovin; V. I. Fedorets

1986-01-01

175

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

176

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

177

Effect of boron on the development of brown rot ( Monilinia laxa) on peaches  

Microsoft Academic Search

Requirements of consumers for products with low residues of pesticides have increased the need for alternative disease management practices. The concentration of boron in fruit affects its quality, shelf life and the development of physiological disorders. However, the effect of boron on the susceptibility of peach to fruit rots has not been reported. This study investigated the effect of boron

T. Thomidis; E. Exadaktylou

2010-01-01

178

Certain features of the preparation of boron powders in x-ray diffraction investigations  

Microsoft Academic Search

It is known that elemental boron is characterized by an increased reaction capacity toward oxygen. Boron powders oxidize especially intensely. Under real conditions, boron powders always contain a certain quantity of oxide phase (primarily in the form of B2O3), the quantity of which depends on their degree of dispersion, the method of production, and the storage conditions. In long exposure

G. V. Tsagareishvili; D. A. Avlokhashvili; I. A. Bairamashvili; T. V. Dolidze; D. L. Gabuniya; T. G. Nakashidze; K. A. Oganezov; M. L. Tabutsidze

1985-01-01

179

Role of boron carbide in carbothermic formation of hexagonal boron nitride  

Microsoft Academic Search

Formation of hexagonal boron nitride by carbothermic reduction of boric oxide under nitrogen atmosphere at 1500C was investigated. Experiments were performed for durations in the range of 15min to 3h. Reaction products were subjected to powder X-ray diffraction analysis, chemical analysis and were examined by scanning electron microscope. Formation of hexagonal boron nitride was found to be complete in 3h

H. E. amurlu; N. Sevin; Y. Topkaya

2006-01-01

180

Activation and deprotection of F-BODIPYs using boron trihalides.  

PubMed

The activation of F-BODIPYs with boron trihalides, followed by treatment with a nucleophile, effects facile substitution at boron; using water as the nucleophile promotes deprotective removal of the -BF2 moiety and thereby production of the corresponding parent dipyrrin salt in quantitative yield under extremely mild conditions. PMID:24849815

Lundrigan, Travis; Cameron, T Stanley; Thompson, Alison

2014-07-01

181

Lipase-catalyzed highly enantioselective kinetic resolution of boron-containing chiral alcohols.  

PubMed

The first application of enzymes as catalysts to obtain optically pure boron compounds is described. The kinetic resolution of boron-containing chiral alcohols via enantioselective transesterification catalyzed by lipases was studied. Aromatic, allylic, and aliphatic secondary alcohols containing a boronate ester or boronic acid group were resolved by lipase from Candida antartica (CALB), and excellent E values (E > 200) and high enantiomeric excesses (up to >99%) of both remaining substrates and acetylated product were obtained. PMID:19552446

Andrade, Leandro H; Barcellos, Thiago

2009-07-16

182

Process for microwave sintering boron carbide  

Microsoft Academic Search

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

C. E. Holcombe; M. S. Morrow

1993-01-01

183

Microwave sintering of boron carbide  

Microsoft Academic Search

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

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

1988-01-01

184

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

185

Boron in the marine atmosphere  

NASA Astrophysics Data System (ADS)

Atmospheric boron was simultaneously separated into gaseous and particulate components for the first time by passing air through a simple impregnated filter sampling system. A Nuclepore filter collected particular boron and preceded KOH impregnated Whatman 41 filters for gaseous boron collection. Boron was determined by visible spectrophotometry. The method was developed to allow daily measurements of atmospheric boron. The results show that boron exists in the atmosphere primarily in the gas phase. Gaseous boron concentrations collected at several sites in the Northern Hemisphere ranged from 1-233 ng/cu m while particulate boron ranged from 0.02-8 ng/cu m. A four month series of daily samples collected at Narragansett, R.I. revealed gaseous boron variations to exist on a time scale of several days. Estimate of inputs of boron to the troposphere reveal that the ocean and vulcanism are the major natural sources, dominating anthropogenic sources, such as coal combustion, by a factor of approx 10.

Fogg, T. R.

186

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

187

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

188

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

189

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

190

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

191

Radioisotope Reduction Using Solar Power for Outer Planetary Missions.  

National Technical Information Service (NTIS)

Radioisotope power systems have historically been (and still are) the power system of choice from a mass and size perspective for outer planetary missions. High demand for and limited availability of radioisotope fuel has made it necessary to investigate ...

J. Fincannon

2008-01-01

192

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

193

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)

Moseman, R F

1994-01-01

194

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.

Woods, W G

1994-01-01

195

Radioisotope Thermoelectric Power Systems: Enabling Technology for European Space Exploration Missions  

NASA Astrophysics Data System (ADS)

Radioisotope power systems (RPS) have proved critical enablers for many of the most demanding space and planetary science missions. US systems, fuelled by 238Pu, have returned extraordinary science from missions such as the Pioneer and Voyager probes, Galileo (Jupiter) and Cassini (Saturn). At the time of writing, New Horizons and Mars Science Laboratory are en route to Pluto and Mars respectively and are equipped with Radioisotope Thermoelectric Generators (RTG). RPSs can provide electrical power to spacecraft systems independently of solar energy, permitting more capable and productive spacecraft and missions. Europe is focused on developing 241Am powered RPSs.

Williams, H. R.; Ambrosi, R. M.; Bannister, N. P.; Samara-Ratna, P.; Tinsley, T. P.; Rice, T.; Sarsfield, M. J.; Cordingley, L.; Slade, R.; Deacon, T.; Jorden, A.; Johnson, W.; Stephenson, K.

2012-09-01

196

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

197

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

198

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

199

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.

200

Safety monitoring system for radioisotope thermoelectric generators  

NASA Technical Reports Server (NTRS)

System alerts personnel of hazards which may develop while they are performing tests on radioisotope thermoelectric generator (RTG). Remedial action is initiated to minimize damage. Five operating conditions are monitored: hot junction temperature, cold junction temperature, thermal shroud coolant flow, vacuum in test chamber, and alpha radiation.

Zoltan, A.

1973-01-01

201

MARINE GEOCHEMICAL STUDIES WITH FALLOUT RADIOISOTOPES  

Microsoft Academic Search

The peaceful and military uses of atomic energy are resulting in the ; introduction to the world's oceans of new radioisotopes in significant amounts ; and of natural at rates different from those which have been previously obtained. ; In the Atlantic Ocean thus far significant additions have been made only by fall-; out at the surface. Measurements in this

V. T. Bowen; T. T. Sugihara

1958-01-01

202

A RADIOISOTOPE TRAINING CENTER AT REHOVOTH, ISRAEL  

Microsoft Academic Search

A training school in the various applications of radioisotopes was ; established at the Weizmann Institute of Science, Rehovoth, Israel. In order to ; get the best results, the number of participants in each training course was ; limited to 12 to 18 persons, all of a similar scientific or technical background ; and with similar prospects of work in

Anbar

1959-01-01

203

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

Microsoft Academic Search

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

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

1992-01-01

204

Ionicities of Boron-Boron Bonds in B12 Icosahedra  

Microsoft Academic Search

First-principles calculations are used to investigate ionicities of boron-boron bonds in B12 icosahedra. It is observed that the geometrical symmetry breaking of B12 icosahedra results in the spatial asymmetry of charge density on each boron-boron bond, and further in the ionicity of B12 icosahedra. The results calculated by a new ionicity scale, a population ionicity scale, indicate that the maximum

Julong He; Erdong Wu; Huitian Wang; Riping Liu; Yongjun Tian

2005-01-01

205

Diffusion boronizing of molybdenum and niobium in boron carbide powder  

Microsoft Academic Search

1.A study was made of the boronizing of molybdenum and niobium in boron carbide powder with or without additions of halogen-containing activating agents.2.It was established that salts of hydrofluoboric acid are the most effective activating agents.3.The boronizing of refractory metals and alloys in commercial boron carbide powders ensures a comparatively high rate of coating formation and gives high quality of

L. A. Sosnovskii; A. P. pik; A. P. Kraplya

1972-01-01

206

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

Microsoft Academic Search

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

1997-01-01

207

Non-radioisotope detection of pol sequences of HTLV1 proviral DNA: Standardisation and sensitivity analysis  

Microsoft Academic Search

Proviral DNA amplification methods may be used for identification of HTLV-1 infection or in basic virology research. Published standardised methods in this regard usually depend on hybridisation of PCR products with radioisotope-labelled probes. However, this procedure has limited use in routine testing, due to environmental and health risks. The aim was to assess the feasibility of routine use and the

Jos Marcos Pereira Costa; Laura Massami Sumita; Aluisio Cotrim Segurado

2006-01-01

208

Single stage ECR ion source for the mass separation of xenon radioisotopes  

Microsoft Academic Search

The main features of ECR ion sources (high efficiency, almost unlimited lifetime, stable running conditions, low ion energy spread) make them, when optimized for a high yield at charge state 1+, ideally suited for on-line mass separation. For this reason a single stage 6.4 GHz test source was built for the Paul Scherrer Institute medical radioisotope production facility. Source geometry

M. Hofer; H. W. Reist

1990-01-01

209

Determination of Boron and Carbon in Reactor Grade Boron Carbide.  

National Technical Information Service (NTIS)

The sealed tube method of dissolution at high temperature and pressure has been successfully applied in the analysis of reactor grade boron carbide for the determination of boron. A 50 mg sample of boron carbide is completely dissolved by heating with con...

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

1978-01-01

210

Microstructure Analysis of Boron Nanotubes.  

National Technical Information Service (NTIS)

Transmission electron microscopy and electron diffraction technique revealed boron nitride nanotube and nanoparticles in thin film boron nitride prepared by CVD method. Electron micrographs show single walled nanotubes containing these nonoparticles. The ...

E. Jelis S. Kerwien T. Chatterjee

2012-01-01

211

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

PubMed

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. PMID:18052251

Arenal, Raul; Stephan, Odile; Cochon, Jean-Lou; Loiseau, Annick

2007-12-26

212

Boron incorporation into mullite  

NASA Astrophysics Data System (ADS)

Boron-doped mullites were synthesized using aluminium nitrate-nonahydrate, tetraethoxysilane and boric acid in a sol gel process with subsequent annealing at 950 and 1300 C for five hours. Two different bulk compositions with constant Al2O3 contents (60 and 70 mol%, respectively) and varying SiO2 plus B2O3 contents were investigated. X-ray powder diffraction analyses yielded a linear decrease of the lattice parameters with increasing bulk B2O3 content, which was interpreted as to be due to boron incorporation. Related to the increasing boron content, corresponding infrared spectra revealed a slight and continuous shift for most of the absorption bands. These data show that mullite is able to incorporate large amounts of boron into its structure (up to about 20 mol% B2O3 depending on the bulk composition of the starting materials). Infrared analyses suggest that boron is incorporated into the mullite structure in form of planar three-fold coordinated BO3 groups.

Griesser, K. J.; Beran, A.; Voll, D.; Schneider, H.

2008-03-01

213

Boron and lithium isotopic composition in chondrules from the mokoia meteorite  

NASA Astrophysics Data System (ADS)

Introduction: Large Boron isotopic variations have been reported in individual chondrules from several meteorites [1, 2]. These variations were interpreted as resulting from the incomplete mixing of two isotopically distinct sources of Boron. Spallation is the only known nucleosynthetic process that can yield Boron in substantial amounts at the scale of the Universe. Therefore it has been proposed that the two sources observed in chondrules correspond to two different types of spallation reactions, namely at high and low energies. Indeed, in the case of Boron, the 11B/10B ratio is sensitive to the energy at which the spallation reaction takes place. Since this report of large B isotopic variations in chondrules, two observations have allowed to identify the natural conditions under which at least one of such spallation reactions may have taken place in the early solar system. First, X-ray observations of T-Tauri stars have revealed daily outbursts which mimic the present day solar activity during the emission of flares [3]. Second, the decay product (i.e. 10B) of the short lived radio-isotope 10Be was discovered in Calcium-Aluminum-rich inclusions (CAIs) [4]. This is an indication that spallation did occurr in the solar system, shortly (i.e. less than a few million years) before the formation of the CAIs. In addition the possible occurrence of 7Be in CAIs suggests that this duration can be as short as a few months [5]. Sampling and Results: In the 8 chondrules from Mokoia, the ?11B values range between -396.8 ppm and -0.67.8 ppm (2 sigma). In one Boron depleted area of one chondrule, the ?11B value was found to be as low as -68.5 ppm and -61.5 ppm (29; 2 sigma). In one chondrule from Mokoia the ?11B values range between -33.75.4 ppm and -3.85.4 ppm. These data confirm with a resolution of ? 6 ppm the presence of a significant Boron isotopic heterogeneity,.The ?^7Li were also measured along with the ^delta11B. They range from -53.72.4 and -0.151.6 ppm (2 sigma) in the 8 chondrules of the Mokoia meteorite. Therefore the heterogeneity in B has its counterpart for Li. Interpretation: A two end member mixing model members can be proposed : ?11B ?0 ppm and ?11B<= -70 ppm. The value of 0 ppm is still significantly different from the matrix value reported by [6] (+19.2 ppm) and thus the possible contamination of the chondrule by their surrounding matrix is highly unlikely. The second end member should have ?11B and ?^7Li values le-70 ppm and le-50 ppm, respectively, resulting from Li and B produced at high energy by spallation reactions (E >= 100 MeV/nucleon, ?11B =-375 ?^7Li = -830 ppm). References: [1] Chaussidon M., Robert F. (1995) Nature 374, 337-339. [2] Chaussidon M. and Robert F. (1998) Earth Planet Sci. Lett. 164, 577-589. [3] Montmerle T. (1999) MPE Report : Astronomy with Radioactivities, 225-236. [4] McKeegan K., Chaussidon M., Robert F. (2000) Science 289, 1334-1337. [5] Chaussidon M., Robert F. McKeegan K. (2002) Abst. 33th LPSC #1563 [6] Hoppe et al., (2001) MAPS, 36, 1331-1343. [7] Zhai M et al., (1996) Geochim. Cosmochim. Acta 60, 4877-4881.

Robert, F.; Chaussidon, M.

2003-04-01

214

Particle-beam accelerators for radiotherapy and radioisotopes  

SciTech Connect

The philosophy used in developing the new PIGMI technology was that the parameters chosen for physics research machines are not necessarily the right ones for a dedicated therapy or radioisotope machine. In particular, the beam current and energy can be optimized, and the design should emphasize minimum size, simplicity and reliability of operation, and economy in capital and operating costs. A major part of achieving these goals lay in raising the operating frequency and voltage gradient of the accelerator, which shrinks the diameter and length of the components. Several other technical innovations resulted in major system improvements. One of these is a radically new type of accelerator structure named the radio-frequency quadrupole (RFQ) accelerator. This allowed us to eliminate the large, complicated ion source used in previous ion accelerators, and to achieve a very high quality accelerated beam. Also, by using advanced permanent magnet materials to make the focusing elements, the system becomes much simpler. Other improvements have been made in all of the accelerator components and in the methods for operating them. These will be described, and design and costing information examples given for several possible therapy and radioisotope production machines.

Boyd, T.J.; Crandall, K.R.; Hamm, R.W.

1981-01-01

215

Plasma boron and the effects of boron supplementation in males.  

PubMed Central

Recently, a proliferation of athletic supplements has been marketed touting boron as an ergogenic aid capable of increasing testosterone. The effect of boron supplementation was investigated in male bodybuilders. Ten male bodybuilders (aged 20 to 26) were given a 2.5-mg boron supplement, while nine male bodybuilders (aged 21 to 27) were given a placebo for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on day 1 and day 49 of the study. A microwave digestion procedure followed by inductively coupled argon plasma spectroscopy was used for boron determination. Twelve subjects had boron values at or above the detection limit with median value of 25 ng/ml (16 ng/ml lower quartile and 33 ng/ml upper quartile). Of the ten subjects receiving boron supplements, six had an increase in their plasma boron. Analysis of variance indicated no significant effect of boron supplementation on any of the other dependent variables. Both groups demonstrated significant increases in total testosterone (p < 0.01), lean body mass (p < 0.01), and one repetition maximum (RM) squat (p < 0.001) and one RM bench press (p < 0.01). The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all.

Green, N R; Ferrando, A A

1994-01-01

216

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

217

Low energy Auger transitions of boron in several boron compounds  

Microsoft Academic Search

Boron KVV Auger spectra of B4C, BN, and B2O3 are compared with that of pure boron. The observed characteristic changes in the low energy features of the spectra are shown to be dependent on the compound partner of boron, which supplies extra decay channels. The main features of the Auger multiplet can be described in terms of an interatomic transition

G. Hanke; K. Mueller

1984-01-01

218

Boron-copper neutron absorbing material and method of preparation  

DOEpatents

A composite, copper clad neutron absorbing material is comprised of copper powder and boron powder enriched with boron 10. The boron 10 content can reach over 30 percent by volume, permitting a very high level of neutron absorption. The copper clad product is also capable of being reduced to a thickness of 0.05 to 0.06 inches and curved to a radius of 2 to 3 inches, and can resist temperatures of 900.degree. C. A method of preparing the material includes the steps of compacting a boron-copper powder mixture and placing it in a copper cladding, restraining the clad assembly in a steel frame while it is hot rolled at 900.degree. C. with cross rolling, and removing the steel frame and further rolling the clad assembly at 650.degree. C. An additional sheet of copper can be soldered onto the clad assembly so that the finished sheet can be cold formed into curved shapes.

Wiencek, Thomas C. (Bolingbrook, IL); Domagala, Robert F. (Indian Head Park, IL); Thresh, Henry (Palos Hts., IL)

1991-01-01

219

Boron based complex wear-resistant coatings  

Microsoft Academic Search

Applying boron, boron-copper, and boron-nickel diffusion coatings to die steels, as well as the microhardness, microbrittleness\\u000a and wear resistance of the steels with the coatings are considered.

Yu. A. Balandin

2006-01-01

220

Facile Analysis and Sequencing of Linear and Branched Peptide Boronic Acids by MALDI Mass Spectrometry  

PubMed Central

Interest in peptides incorporating boronic acid moieties is increasing due to their potential as therapeutics/diagnostics for a variety of diseases such as cancer. The utility of peptide boronic acids may be expanded with access to vast libraries that can be deconvoluted rapidly and economically. Unfortunately, current detection protocols using mass spectrometry are laborious and confounded by boronic acid trimerization, which requires time consuming analysis of dehydration products. These issues are exacerbated when the peptide sequence is unknown, as with de novo sequencing, and especially when multiple boronic acid moieties are present. Thus, a rapid, reliable and simple method for peptide identification is of utmost importance. Herein, we report the identification and sequencing of linear and branched peptide boronic acids containing up to five boronic acid groups by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Protocols for preparation of pinacol boronic esters were adapted for efficient MALDI analysis of peptides. Additionally, a novel peptide boronic acid detection strategy was developed in which 2,5-dihydroxybenzoic acid (DHB) served as both matrix and derivatizing agent in a convenient, in situ, on-plate esterification. Finally, we demonstrate that DHB-modified peptide boronic acids from a single bead can be analyzed by MALDI-MSMS analysis, validating our approach for the identification and sequencing of branched peptide boronic acid libraries.

Crumpton, Jason; Zhang, Wenyu; Santos, Webster

2011-01-01

221

Boron nitride nanotubes  

Microsoft Academic Search

The successful synthesis of pure boron nitride (BN) nanotubes is reported here. Multi-walled tubes with inner diameters on the order of 1 to 3 nanometers and with lengths up to 200 nanometers were produced in a carbon-free plasma discharge between a BN-packed tungsten rod and a cooled copper electrode. Electron energy-loss spectroscopy on individual tubes yielded B:N ratios of approximately

N. G. Chopra; R. J. Luyken; K. Cherrey; V. H. Crespi; M. L. Cohen; S. G. Louie; A. Zettl

1995-01-01

222

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

223

High efficiency radioisotope thermophotovoltaic prototype generator  

NASA Technical Reports Server (NTRS)

A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the result of the invention of the GaSb infrared sensitive photovoltaic cell. Herein, we present the results of a parametric study of emitters and optical filters in conjuction with existing data on gallium antimonide cells. We compare a polished tungsten emitter with an Erbia selective emitter for use in combination with a simple dielectric filter and a gallium antimonide cell array. We find that the polished tungsten emitter is by itself a very selective emitter with low emissivity beyond 4 microns. Given a gallium antimonide cell and a tungsten emitter, a simple dielectric filter can be designed to transmit radiant energy below 1.7 microns and to reflect radiant energy between 1.7 and 4 microns back to the emitter. Because of the low long wavelength emissivity associated with the polished tungsten emitter, this simple dielectric filter then yields very respectable system performance. Also as a result of the longer wavelength fall-off in the tungsten emissivity curve, the radiation energy peak for a polished tungsten emitter operating at 1300 K shifts to shorter wavelengths relative to the blackbody spectrum so that the radiated energy peak falls right at the gallium antimonide cell bandedge. The result is that the response of the gallium antimonide cell is well matched to a polished tungsten emitter. We propose, therefore, to fabricate an operating prototype of a near term radioisotope thermophotovoltaic generator design consisting of a polished tungsten emitter, standard gallium antimonide cells, and a near-term dielectric filter. The Jet Propulsion Laboratory will design and build the thermal cavity, and JX Crystals will fabricate the gallium antimonide cells, dielectric filters, and resultant receiver panels. With 250 Watts of heat input, we expect this prototype to produce over 300 Watts of electrical energy output for a system energy conversion efficiency of over 12%. This low risk, near term design provides advances relative to present radioisotope thermophotovoltaic generators and has the additional advantage of allowing component and system development and testing to begin immediately. Improved cells and filters can easily be incorporated in this baseline system if they should become available in the future.

Avery, James E.; Samaras, John E.; Fraas, Lewis M.; Ewell, Richard

1995-01-01

224

Cooling radioisotope thermoelectric generators in the Shuttle  

NASA Technical Reports Server (NTRS)

Radioisotope thermoelectric generators (RTG) to be used on future spacecraft and launched by the Shuttle must be cooled from the time they are installed and enclosed until the spacecraft is deployed from the Shuttle. A special Cooling Kit maintains their temperature well below critical by circulating water through the coils soldered to them and through a heat exchanger that boils water and externally discharges the resulting steam. The RTG Cooling Kit, including its support frame, if fully charged with about 64 kg of evaporation water, will increase the Shuttle launch mass by about 200 kg.

Norman, R. M.

1978-01-01

225

High efficiency radioisotope thermophotovoltaic prototype generator  

NASA Astrophysics Data System (ADS)

A radioisotope thermophotovoltaic generator space power system (RTPV) is lightweight, low-cost alternative to the present radioisotope thermoelectric generator system (RTG). The fabrication of such an RTPV generator has recently become feasible as the result of the invention of the GaSb infrared sensitive photovoltaic cell. Herein, we present the results of a parametric study of emitters and optical filters in conjuction with existing data on gallium antimonide cells. We compare a polished tungsten emitter with an Erbia selective emitter for use in combination with a simple dielectric filter and a gallium antimonide cell array. We find that the polished tungsten emitter is by itself a very selective emitter with low emissivity beyond 4 microns. Given a gallium antimonide cell and a tungsten emitter, a simple dielectric filter can be designed to transmit radiant energy below 1.7 microns and to reflect radiant energy between 1.7 and 4 microns back to the emitter. Because of the low long wavelength emissivity associated with the polished tungsten emitter, this simple dielectric filter then yields very respectable system performance. Also as a result of the longer wavelength fall-off in the tungsten emissivity curve, the radiation energy peak for a polished tungsten emitter operating at 1300 K shifts to shorter wavelengths relative to the blackbody spectrum so that the radiated energy peak falls right at the gallium antimonide cell bandedge. The result is that the response of the gallium antimonide cell is well matched to a polished tungsten emitter. We propose, therefore, to fabricate an operating prototype of a near term radioisotope thermophotovoltaic generator design consisting of a polished tungsten emitter, standard gallium antimonide cells, and a near-term dielectric filter. The Jet Propulsion Laboratory will design and build the thermal cavity, and JX Crystals will fabricate the gallium antimonide cells, dielectric filters, and resultant receiver panels. With 250 Watts of heat input, we expect this prototype to produce over 300 Watts of electrical energy output for a system energy conversion efficiency of over 12%. This low risk, near term design provides advances relative to present radioisotope thermophotovoltaic generators and has the additional advantage of allowing component and system development and testing to begin immediately. Improved cells and filters can easily be incorporated in this baseline system if they should become available in the future.

Avery, James E.; Samaras, John E.; Fraas, Lewis M.; Ewell, Richard

1995-10-01

226

RADIOISOTOPE ELECTRIC PROPULSION FOR NEW FRONTIERS CLASS MISSIONS  

Microsoft Academic Search

With the initiation of the New Frontiers Class of space science missions, small radioisotope powered spacecraft for outer planet exploration will become reality. In order for these missions to co-orbit various primitive objects and moons of interest, a highly efficient electric propulsion system is needed. The use of such a radioisotope electric propulsion system is enabled by a new direct

Steven Oleson; Scott Benson; Michael Patterson; Jeffrey Schreiber; Douglas Fiehler

2003-01-01

227

RADIOISOTOPE EXPERIMENTS IN HIGH SCHOOL BIOLOGY, AN ANNOTATED SELECTED BIBLIOGRAPHY.  

ERIC Educational Resources Information Center

SELECTED REFERENCES ON THE USE OF RADIOISOTOPES IN BIOLOGY ARE CONTAINED IN THIS ANNOTATED BIBLIOGRAPHY FOR SECONDARY SCHOOL STUDENTS. MATERIALS INCLUDED WERE PUBLISHED AFTER 1960 AND DEAL WITH THE PROPERTIES OF RADIATION, SIMPLE RADIATION DETECTION PROCEDURES, AND TECHNIQUES FOR USING RADIOISOTOPES EXPERIMENTALLY. THE REFERENCES ARE LISTED IN

HURLBURT, EVELYN M.

228

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.

Shah, Ashwin R.; Schreiber, Jeffrey G.

2004-01-01

229

The GPR-1 longitudinal radioisotope gamma tomograph  

SciTech Connect

Instruments for visualization of the distribution of radioindicators administered for diagnostic purposes, including scanners and gamma cameras, have become widely used in the diagnosis of diseases of organs and systems such as the liver, kidney, brain, lungs, thyroid gland, and skeletal system and also to detect primary and metastatic neoplasms. In these instruments the three-dimensional test object is shown as two-dimensional projections. This leads to loss or distortion of diagnostic information, for the surrounding structures, which accumulate the radioindicator, mask pathological foci and interfere with their correct identification. These disadvantages can be overcome completely or partially by the use of tomographic methods and systems of radioisotope visualization. Tomographic instruments (gamma tomographs) visualize the distribution of a radioindicator in several parallel layers of the object. Taken together, a sufficient number of these layer-by-layer images (gamma tomograms) gives a more complete and accurate picture of the true spatial distribution of the radioindicator in the test organ. Radioisotope gamma tomographs can be divided into two types: longitudinal and transverse. Instruments of the first type give tomograms in sections parallel to the patient's longitudinal axis. In instruments of the second type, the pictures obtained correspond to sections made perpendicular to this direction.

El'kind, E.Yu.; Chernobrovkin, V.P.; Kalantarov, K.D.; Kangun, A.L.; Sidorov, Yu.M.; Tyurin, V.G.

1983-03-01

230

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

231

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

232

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

233

Boron isotopic compositions of some boron minerals  

SciTech Connect

Boron minerals that have different structural formulae but are supposed to have the same geologic origin have been collected and analyzed for the {sup 11}B/{sup 10}B isotopic ratio. It has been reconfirmed that minerals of marine origin have higher {sup 11}B/{sup 10}B ratios than those of nonmarine origin. It has been found that the sequence of decreasing {sup 11}B/{sup 10}B 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 high BO{sub 3}/BO{sub 4} ratios, (the ratio of the number of the BO{sub 3} triangle units to the number of the BO{sub 4} tetrahedron units in the structural formula of a mineral) have higher {sup 11}B/{sup 10}B ratios.

Oi, Takao; Musashi, Masaaki; Ossaka, Tomoko; Kakihana, Hidetake (Sophia Univ., Tokyo (Japan)); Nomura, Masao; Okamoto, Makoto (Tokyo Institute of Technology (Japan))

1989-12-01

234

Assessment of radioisotope heaters for remote terrestrial applications  

SciTech Connect

This paper examines the feasibility of using radioisotope byproducts for special heating applications at remote sites in Alaska and other cold regions. The investigation included assessment of candidate radioisotope materials for heater applications, identification of the most promising cold region applications, evaluation of key technical issues and implementation constraints, and development of conceptual heater designs for candidate applications. Strontium-90 (Sr-90) was selected as the most viable fuel for radioisotopic heaters used in terrestrial applications. Opportunities for the application of radioisotopic heaters were determined through site visits to representative Alaska installations. Candidate heater applications included water storage tanks, sludge digesters, sewage lagoons, water piping systems, well-head pumping stations, emergency shelters, and fuel storage tank deicers. Radioisotopic heaters for water storage tank freeze-up protection and for enhancement of biological waste treatment processes at remote sites were selected as the most promising applications.

Uherka, K.L.

1987-05-01

235

Experimental and theoretical studies of ignition and combustion of boron particles in wet and dry atmospheres  

Microsoft Academic Search

Experiments were performed on the ignition and combustion of fine boron particles in hot wet gas. In these experiments a steady nitrogen jet transporting the particles at low loading densities was injected coaxially into the combustion products of a flat-flame burner. Three powder samples, having diameters around 0.1, 7, and 10 microns were studied. The types of boron flames that

Shuichi

1990-01-01

236

Relationships of anion-exchange sorption of boron from natural thermal-spring water  

Microsoft Academic Search

Boric acid is one of the characteristic components of Kamchatka waters. Extraction of boron from thermal waters for production of potable water is closely linked with current problems of multiproduct utilization of resources and protection of the environment. The authors have investigated the possibilities of using ion exchange for extraction of boron from natural waters, and studied the sorption relationships

N. R. Meichik; Yu. A. Leikin; M. A. Antipov; N. V. Goryacheva; I. S. Klimenko; S. A. Medvedev; N. B. Galitskaya

1988-01-01

237

Influence of biofouling on boron removal by nanofiltration and reverse osmosis membranes  

Microsoft Academic Search

Excess of boron in water poses a problem due to adverse effects on crop production as well as human health and aquatic life. This study examined the influence of biofouling of NF and RO membrane on the performance of the membranes in removing boron from a synthetic wastewater effluent. Accelerated laboratory-scale biofouling experiments were carried out with commercial thin film

Esther Huertas; Moshe Herzberg; Gideon Oron; Menachem Elimelech

2008-01-01

238

Modification of mechanical properties of nitrogen-sputtered boron nitride films by ion bombardment  

Microsoft Academic Search

Boron nitride is a fascinating coating material, both in the electronics industry and for tribological applications. For the various applications the crystalline structure is important, and there is a need for studies of its basic nature and of its surface modification by ion beams. A large variety of high temperature processes for production of boron nitride exists, whereas there are

H. Jensen; U. M. Jensen; G. Sorensen

1995-01-01

239

Boron carbide-aluminum cermets  

SciTech Connect

We have developed boron carbide-aluminum cermets by means of thermodynamic, kinetic, and processing studies. Our research indicates that boron carbide-aluminum cermets offer ''tailorable'' microstructures with designable properties through process control. This new class of cermets has the potential to become a very important material with wide industrial applications.

Halverson, D.C.

1986-09-03

240

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

241

Boron incorporation into mullite  

Microsoft Academic Search

SummaryBoron-doped mullites were synthesized using aluminium nitrate-nonahydrate, tetraethoxysilane and boric acid in a solgel process\\u000a with subsequent annealing at 950 and 1300?C for five hours. Two different bulk compositions with constant Al2O3 contents (60 and 70?mol%, respectively) and varying SiO2 plus B2O3 contents were investigated. X-ray powder diffraction analyses yielded a linear decrease of the lattice parameters with increasing\\u000a bulk

K. J. Griesser; A. Beran; D. Voll; H. Schneider

2008-01-01

242

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

243

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

244

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

245

Radioisotope Reduction Using Solar Power for Outer Planetary Missions  

NASA Technical Reports Server (NTRS)

Radioisotope power systems have historically been (and still are) the power system of choice from a mass and size perspective for outer planetary missions. High demand for and limited availability of radioisotope fuel has made it necessary to investigate alternatives to this option. Low mass, high efficiency solar power systems have the potential for use at low outer planetary temperatures and illumination levels. This paper documents the impacts of using solar power systems instead of radioisotope power for all or part of the power needs of outer planetary spacecraft and illustrates the potential fuel savings of such an approach.

Fincannon, James

2008-01-01

246

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

247

Boron fullerenes: From B80 to hole doped boron sheets  

Microsoft Academic Search

We demonstrate the existence of a family of stable boron fullerenes containing 80n2 atoms that is related to the family of 60n2 carbon icosahedral fullerene series and is compatible with the recently proposed stable boron sheets composed of triangular and hexagonal motifs. All electron density-functional calculations on the B320 , B720 , B1280 , and B2000 confirm their stability and

Rajendra R. Zope; Tunna Baruah; K. C. Lau; Amy Y. Liu; M. R. Pederson; B. I. Dunlap

2009-01-01

248

Evaluation of boron chelates in extracting soil boron  

Microsoft Academic Search

The hot water extractable boron (HWB) soil?test procedure does not lend itself to rapid routine analysis. This study was conducted to evaluate boron (B) chelates in extracting soil B in comparison to the HWB soil?test procedure. The following B chelates were examined as soil B extractants: mannitol, salicylic acid, 2?hydroxyisobutyric acid, and sorbitol. Soil B chelate extractants were prepared in

Byron Vaughan; John Howe

1994-01-01

249

Nuclear energy in the service of biomedicine: the U.S. Atomic Energy Commission's radioisotope program, 1946-1950.  

PubMed

The widespread adoption of radioisotopes as tools in biomedical research and therapy became one of the major consequences of the "physicists' war" for postwar life science. Scientists in the Manhattan Project, as part of their efforts to advocate for civilian uses of atomic energy after the war, proposed using infrastructure from the wartime bomb project to develop a government-run radioisotope distribution program. After the Atomic Energy Bill was passed and before the Atomic Energy Commission (AEC) was formally established, the Manhattan Project began shipping isotopes from Oak Ridge. Scientists and physicians put these reactor-produced isotopes to many of the same uses that had been pioneered with cyclotron-generated radioisotopes in the 1930s and early 1940s. The majority of early AEC shipments were radioiodine and radiophosphorus, employed to evaluate thyroid function, diagnose medical disorders, and irradiate tumors. Both researchers and politicians lauded radioisotopes publicly for their potential in curing diseases, particularly cancer. However, isotopes proved less successful than anticipated in treating cancer and more successful in medical diagnostics. On the research side, reactor-generated radioisotopes equipped biologists with new tools to trace molecular transformations from metabolic pathways to ecosystems. The U.S. government's production and promotion of isotopes stimulated their consumption by scientists and physicians (both domestic and abroad), such that in the postwar period isotopes became routine elements of laboratory and clinical use. In the early postwar years, radioisotopes signified the government's commitment to harness the atom for peace, particularly through contributions to biology, medicine, and agriculture. PMID:17575955

Creager, Angela N H

2006-01-01

250

Copper passivation of boron in silicon and boron reactivation kinetics  

NASA Astrophysics Data System (ADS)

Copper passivation of substitutional boron in single-crystal silicon and the reactivation kinetics of the passivated boron have been investigated with the use of Schottky-barrier structures formed by the deposition of copper on boron-doped silicon at room temperature. It is found that passivation of the boron acceptors occurs after copper deposition. The results suggest that the fast-diffusing interstitial Cu+ passivates the boron acceptors by forming neutral B-Cu complexes, rather than by direct compensation. No compensating donor levels associated with Cu are observed. These results are consistent with recent theoretical predictions. The reactivation kinetics are first order with an activation energy of 0.89 eV, and the annealing process is found to be controlled by long-range diffusion, rather than by pure dissociation. The thermal dissociation of the B-Cu complexes is driven by the formation of the copper silicide ?'-Cu3Si, indicating the importance of silicide formation in the reactivation of the boron acceptors.

Aboelfotoh, M. O.; Svensson, B. G.

1991-12-01

251

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

252

Neptune Orbiters Utilizing Solar and Radioisotope Electric Propulsion.  

National Technical Information Service (NTIS)

In certain cases, Radioisotope Electric Propulsion (REP), used in conjunction with other propulsion systems, could be used to reduce the trip times for outer planetary orbiter spacecraft. It also has the potential to improve the maneuverability and power ...

D. I. Fiehler S. R. Oleson

2004-01-01

253

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 50.5nm 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

254

Development of an Integrated Robotic Radioisotope Identification and Location System.  

National Technical Information Service (NTIS)

This project involves integrating a commercially available Hyper Pure Germanium (HPGe) system within a robotic base in order to inspect an area for either radioisotopes that could be used for a radiological dispersal device (RDD) or are classified as Spec...

C. J. Moore

2009-01-01

255

Formulation of Boronic Acid Compounds.  

National Technical Information Service (NTIS)

The invention relates to the formulation of pharmaceutical compounds. More particularly, the invention provides stable, pharmaceutically acceptable compositions prepared from boronic acid compounds and methods for preparing the compositions. The invention...

L. Plamondon L. Grenier J. Adams S. L. Gupta

2005-01-01

256

Microstructure Analysis of Boron Nitride.  

National Technical Information Service (NTIS)

Transmission electron microscopy and electron diffraction technique revealed boron nitride nanotube (BNNT) and nanoparticles in thin film baron nitride prepared by chemical vapor deposition method. Electron micrographs show single walled nanotubes contain...

E. Jelis S. Kerwien T. Chatterjee

2009-01-01

257

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

258

Boronization in textor  

NASA Astrophysics Data System (ADS)

The liner and limiters of TEXTOR have been coated in situ with a boron containing carbon film using a RG discharge in a throughflow of 0.8 He + 0.1 B 2H 6 +0.1 CH 4. The average film thickness was 30-50 nm, the ratio of boron and carbon in the layer was about 1:1 according to Auger Electron Spectroscopy. Subsequent tokamak discharges are characterized by a small fraction of radiated power (< 0.3) even during high power ICRF heating (2.6 MW, 1.6 s). A concomitant strong increase of the convective power loading of the limiters is observed. Values of Z eff lower than 1.2 are derived from conductivity measurements. The most prominent change in the impurity concentration compared to good conditions in a carbonized surrounding is measured for oxygen. The value OVI/ ne of the OVI intensity normalized to the averaged plasma density overlinene decreases by more than a factor of four. The decrease in the oxygen content manifests itself also as a reduction of the CO and CO 2 partial pressures measured during and after the discharge with a sniffer probe. The carbon levels are reduced by a factor of about two as measured by the normalized intensity CII/ overlinene of the CII line and via the ratio of the C fluxes and deuterium fluxes measured at the limiter (CI/D ?). The wall shows a pronounced sorption of hydrogen from the plasma, easing the density control and the establishment of low recycling conditions. The beneficial conditions did not show a significant deterioration during more than 200 discharges, including numerous shots at ICRH power levels > 2 MW.

Winter, J.; Esser, H. G.; Knen, L.; Philipps, V.; Reimer, H.; Seggern, J. v.; Schlter, J.; Vietzke, E.; Waelbroeck, F.; Wienhold, P.; Banno, T.; Ringer, D.; Vep?ek, S.

1989-04-01

259

Treatment and conditioning of radioactive solid wastes. Technical manual for the management of low and intermediate level wastes generated at small nuclear research centres and by radioisotope users in medicine, research and industry.  

National Technical Information Service (NTIS)

Radioactive materials are extensively used in industrial and research activities mainly related to medical, agricultural, environmental and other studies and applications. During the application and production of radioisotopes, significant amounts of radi...

1992-01-01

260

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

261

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

262

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

263

Recent advancements in boron nitride nanotubes.  

PubMed

This article provides a concise review of the recent research advancements in boron nitride nanotubes (BNNTs) with a comprehensive list of references. As the motivation of the field, we first summarize some of the attractive properties and potential applications of BNNTs. Then, latest discoveries on the properties, applications, and synthesis of BNNTs are discussed. In particular, we focus on low-temperature and patterned growth, and mass production of BNNTs, since these are the major challenges that have hindered investigation of the properties and application of BNNTs for the past decade. Finally, perspectives of future research on BNNTs are discussed. PMID:20842308

Wang, Jiesheng; Lee, Chee Huei; Yap, Yoke Khin

2010-10-01

264

Purification of single-walled boron nitride nanotubes and boron nitride cages.  

PubMed

Continuous laser vaporization of a BN target under N2 atmosphere is up to now the unique route to single-walled boron nitride nanotubes (BN-SWNTs). Although grams of product can be obtained by this technique, the raw material contains in addition to the BN-SWNTs, different by-products made of boron and nitrogen. Since these materials are undesirable for the studying of the intrinsic properties of the nanotubes, we have undertaken a purification process using chemical and physical methods to separate the different components. We show here that most impurities can be removed by successive cycles of washing, sonication, and centrifugation. Furthermore, the two different types of boron nitride nanostructures i.e., BN-SWNTs and BN-cages can be isolated. Efficiency of the separation was monitored by transmission electron microscopy (TEM) at the different steps of the process. Finally, we envisage the further purification of the nanotubes-enriched fraction by functionalizing the nanotubes in a non covalent manner by specific polymers as for carbon nanotubes and BN multi-walled nanotubes. PMID:18330169

Maguer, A; Arenal, R; Jaffrennou, P; Cochon, J L; Bresson, L; Doris, E; Mioskowski, C; Loiseau, A

2007-10-01

265

Evaluation of ICRF heated discharges with boron coated molybdenum tiles  

Microsoft Academic Search

One of the primary utilization challenges is to minimize impurity production associated with ICRF operation. In present experiments, boronization is frequently applied to control impurities and its lifetime has been observed to be proportional to number of RF Joules injected. We have also observed that RF sheaths localized to field lines connected to the active antenna were responsible for the

S. J. Wukitch; B. Labombard; Y. Lin; B. Lipschultz; E. Marmar; R. Ochoukov; M. L. Reinke; D. G. Whyte

2009-01-01

266

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

267

Synthesis of Boron Nitride Nanotubes for Engineering Applications  

NASA Technical Reports Server (NTRS)

Boron Nitride nanotubes (BNNT) are of interest to the scientific and technical communities for many of the same reasons that carbon nanotubes (CNT) have attracted large amounts of attention. Both materials have potentially unique and significant properties which may have important structural and electronic applications in the future. However of even more interest than their similarities may be the differences between carbon and boron nanotubes. Whilt boron nitride nanotubes possess a very high modulus similaar to CNT, they are also more chemically and thermally inert. Additionally BNNT possess more uniform electronic properties, having a uniform band gap of approximately 5.5 eV while CNT vary from semi-conductin to conductor behavior. Boron Nitride nanotubes have been synthesized by a variety of methods such as chemical vapor deposition, arc discharge and reactive milling. Consistently producing a reliable product has proven difficult. Progress in synthesis of 1-2 gram sized batches of Boron Nitride nanotubes will be discussed as well as potential uses for this unique material.

Hurst, Janet; Hull, David; Gorican, Dan

2005-01-01

268

Initial boronization of PBX-M using ablation from solid boronized probes  

SciTech Connect

Boronization was performed by plasma ablation of two solid boronized target probes. Probe-1, in a mushroom shape, consisted of a 10.7% boronized two-dimensional carbon-carbon composite containing 3.6 g of boron in a B[sub 4]C binder. Probe-2, in a rectangular shape, consisted of an 86% boronized graphite felt composite containing 19.5 g of 40-[mu]m boron particles. Probe-1 boronization deposited [approximately]26 monolayers of boron. After boronization with Probe-1, the loop voltage in 1-MW neutral-beam-heated plasmas decreased 27%, and volt-second consumption decreased 20%. Strong peripheral spectral lines from low-Z elements decreased by factors of [approximately]5. The central oxygen density decreased 15 to 20%. Carbon levels initially increased during boronization but were significantly reduced after boronization. The total radiated power during neutral beam injection decreased by 43%. Probe-2 boronization deposited [approximately]70 monolayers. Probe-2 boronization exhibited similar improved plasma conditions, but for some parameters, a smaller percentage change occurred because of the previous boronization with Probe-1. The ablation rates of both probes were consistent with front-face temperatures above the boron melting point. The results demonstrate the performance of two different boronized probe materials and the relative simplicity and effectiveness of solid target boronization as a convenient, real-time impurity control technique. 20 refs., 10 figs., 1 tab.

Kugel, H.W.; Timberlake, J.; Bell, R.; Kaita, R.; Kaye, S.; Okabayashi, M.; Paul, S.; Takahashi, H.; Tighe, W.; Von Goeler, S. (Princeton Univ., NJ (United States)) (and others)

1994-07-01

269

Snub boron nanostructures: Chiral fullerenes, nanotubes and planar sheet  

Microsoft Academic Search

We design a new class of electronically stable boron nanostructures, viz.: 60n2 boron fullerene family, boron nanotubes, and a planar boron sheet, which like the ?-boron sheet, consists of triangular and hexagonal motifs and has symmetrically arranged hexagonal holes. The binding energy of the proposed new boron sheet is only 0.02eV\\/atom lower than the ?-boron sheet. The 60n2 boron fullerenes

Rajendra R. Zope; Tunna Baruah

2011-01-01

270

Handheld Delivery System for Modified Boron-Type Fire Extinguishment Agent.  

National Technical Information Service (NTIS)

A handheld, portable extinguisher was developed for Boralon, a modified Boron-type Class D fire extinguishing agent. The development of this unit progressed through the design, prototype, and final product stages. Two prototypes were designed as valved, s...

M. E. Lee R. E. Tapscott

1993-01-01

271

Radioisotopic pulmonary lobectomy: feasibility study in dogs  

SciTech Connect

In search for an alternate treatment for inoperable cancer of the lung in humans, we investigated the possibility that introduction of radioactive material into a selected lobe of the canine lung would effectively destroy that lobe without systemic effects or radiation injury to adjacent organs. Ten million ion exchange microspheres labeled with 740 MBq of phosphorus-32 ({sup 32}P) were injected through a catheter placed in a selected lobar branch of a pulmonary artery in 12 anesthetized dogs. Six additional dogs served as controls and received 10 million microspheres not labeled with {sup 32}P. Organs were harvested from 1 wk to 12 mo after injection and examined grossly and histologically. There was progressive organization and contraction of each necrosed {sup 32}P treated lobe which was reduced to a scarred remnant by 12 mo, whereas only minimal inflammatory changes occurred in controls. Of the {sup 32}P injected dose, 94% remained in injected lobe, 4%-5% in nontargeted lobes and less than 0.08% in blood. Radioactivity in liver, kidneys, spleen, heart, and bone marrow was less than 0.1% for each organ. Thus, large doses of radiation in the order of 1,500 Gy can be effectively delivered to a selected lobe to produce radioisotopic pulmonary lobectomy.

Llaurado, J.G.; Brewer, L.A. III; Elam, D.A.; Ing, S.J.; Raiszadeh, M.; Slater, J.M.; Hirst, A.E.; Zielinski, F.W. (Veterans Hospital, Loma Linda, CA (USA))

1990-05-01

272

Reliability of Radioisotope Stirling Convertor Linear Alternator  

NASA Technical Reports Server (NTRS)

Onboard radioisotope power systems being developed and planned for NASA s deep-space missions would require reliable design lifetimes of up to 14 years. Critical components and materials of Stirling convertors have been undergoing extensive testing and evaluation in support of a reliable performance for the specified life span. Of significant importance to the successful development of the Stirling convertor is the design of a lightweight and highly efficient linear alternator. Alternator performance could vary due to small deviations in the permanent magnet properties, operating temperature, and component geometries. Durability prediction and reliability of the alternator may be affected by these deviations from nominal design conditions. Therefore, it is important to evaluate the effect of these uncertainties in predicting the reliability of the linear alternator performance. This paper presents a study in which a reliability-based methodology is used to assess alternator performance. The response surface characterizing the induced open-circuit voltage performance is constructed using 3-D finite element magnetic analysis. Fast probability integration method is used to determine the probability of the desired performance and its sensitivity to the alternator design parameters.

Shah, Ashwin; Korovaichuk, Igor; Geng, Steven M.; Schreiber, Jeffrey G.

2006-01-01

273

Reliability of Radioisotope Stirling Convertor Linear Alternator  

NASA Astrophysics Data System (ADS)

Onboard radioisotope power systems being developed and planned for NASA's deep-space missions would require reliable design lifetimes of up to 14 yr. Critical components and materials of Stirling convertors have been undergoing extensive testing and evaluation in support of a reliable performance for the specified life span. Of significant importance to the successful development of the Stirling convertor is the design of a lightweight and highly efficient linear alternator. Alternator performance could vary due to small deviations in the permanent magnet properties, operating temperature, and component geometries. Durability prediction and reliability of the alternator may be affected by these deviations from nominal design conditions. Therefore, it is important to evaluate the effect of these uncertainties in predicting the reliability of the linear alternator performance. This paper presents a study in which a reliability-based methodology is used to assess alternator performance. The response surface characterizing the induced open-circuit voltage performance is constructed using 3-D finite element magnetic analysis. Fast probability integration method is used to determine the probability of the desired performance and its sensitivity to the alternator design parameters.

Shah, Ashwin; Korovaichuk, Igor; Geng, Steven M.; Schreiber, Jeffrey G.

2005-02-01

274

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

275

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

276

Radioisotope heat source IR and D program. Volume 4. Radioisotope mercury Rankine heat source design, development, and fabrication  

Microsoft Academic Search

For the 2- to 10-kW(e) range of spacecraft power needed for the next decade, mercury Rankine radioisotope power systems offer the technological advantages of a relatively high overall thermal efficiency, a relatively low radiator area, and a high state of the art in hardware development. With the exception of a radioisotope mercury-boiler heat source, extensive development of all components required

1966-01-01

277

Boron doped nanostructured diamond films  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition hydrogen/methane/nitrogen feed-gas mixture with unconventionally high methane (15% CH4 by volume) normally used to grow ultra-hard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane B2H6 for boron-doping of diamond films. The flow rates for B2H 6 and N2 were varied to investigate their effect on plasma chemistry, film structure, boron incorporation, and mechanical properties. It was found that boron atoms can easily be incorporated into diamond films and change the lattice constant and film structure. Nitrogen, on the other hand, competes with boron in the plasma and acts to prevent boron incorporation into the diamond structure. In addition, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well faceted diamond to nanocrystalline diamond. Glancing angle X-ray diffraction and Micro-Raman were used as the main tools to investigate the relation between processing and structure. An optimal N2/CH4 ratio of 0.4 was found to result in a film with a minimum in grain size and surface roughness, along with high boron incorporation (4 x 1020 cm-3). Mechanical properties and thermal stability of boron doped nanostructured diamond films were examined by means of nanoindentation, open air thermal annealing, and nanotribometry. It was found that the films have high hardness close to that of undoped nanostructured diamond films. Thermal stability of these films was evaluated by heating in an oxygen environment above 700C. Improved thermal stability of boron doped nanostructured diamond films was observed. Tribological tests show that although both undoped and boron doped nanostructured diamond films show extremely low coefficient of friction and wear rate as compared with uncoated titanium alloys (Ti-6Al-4V) and cobalt chrome alloy (Co-Cr-Mo), a critical failure max stress of 2.2 GPa was observed for boron doped nanostructured diamond films. A FORTRAN Chemical Kinetics Package for the Analysis of Gas Phase Chemical Kinetics, gas-phase thermodynamic equilibrium calculations involving H 2/CH4/N2/B2H6 mixtures was employed to investigate the chemical interactions leading to boron incorporation and crystalline structure variations. The strong influence of the BH 3 in causing the boron incorporation and the role of CN radical in causing the nanocrystallinity are confirmed by the correlation of their modeled compositions in the gas phase with boron content and degree of nanocrystallinity as determined experimentally. A good degree of agreement was obtained between the theoretically predicted gas phase concentration of species and the experimental concentration trends as measured by the optical emission spectroscopy of the microwave plasma. Overall, high film hardness and toughness, combined with good thermal stability and low surface roughness, indicate that nanostructured boron doped diamond films can be used as wear resistant coatings that are able to withstand high temperature oxidizing environments.

Liang, Qi

278

METHODOLOGICAL DEVELOPMENTS FOR APPLICATION TO THE STUDY OF PHYSIOLOGICAL BORON AND TO BORON NEUTRON CAPTURE THERAPY  

Microsoft Academic Search

The combination of immunogold labelling with electron microscopy or the direct detection of boron by electron energy loss spectrometry have the best lateral resolution for the imaging of boron or boron binding sites in tissues at the sub-cellular level. However these methods do not discriminate the boron isotopes. A number of physical methods make it possible to combine analytical imaging

Michel Thellier; Arlette Chevallier; Isabelle His; Mike C. Jarvis; Mark A. Lovell; Camille Ripoll; David Robertson; Wolfgang Sauerwein; Marie-Claire Verdus

2001-01-01

279

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

280

Synthesis and photocurrent of amorphous boron nanowires.  

PubMed

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. PMID:25061013

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

2014-08-22

281

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

282

Considerations in the fabrication, assembly, and testing of radioisotopic thermo-photovoltaic (RTPV) generators for future space missions  

SciTech Connect

To increase energy output with a smaller size and mass than the radioisotopic thermoelectric generators (RTGs) that were previously used on deep space missions, a radioisotopic thermophotovoltaic (RTPV) system is being developed for the {open_quote}{open_quote}Pluto Express{close_quote}{close_quote} flyby mission. To minimize cost and development time, some facilities and components currently used for RTG production can be used to produce RTPVs. Production options also include out-sourcing and use of off-the-shelf hardware. Necessary modifications to tooling, production equipment, testing and shipping methods can be achieved in a timely manner so that the RTPV will be ready well before the planned launch of {open_quote}{open_quote}Pluto Express.{close_quote}{close_quote} {copyright} {ital 1996 American Institute of Physics.}

Barklay, C.D.; Miller, R.G. [EG& G Mound Applied Technologies, P.O. Box 3000, Miamisburg, Ohio 45343-3000 (United States); Frazier, T.A. [US Department of Energy, P.O. Box 66, Miamisburg, Ohio 45343-0066 (United States)

1996-03-01

283

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

284

Methods and compositions for boronizing metallic surfaces  

SciTech Connect

The present disclosure is directed to methods and compositions for boronizing metal and in particular ferrous surfaces. It has been discovered that if hydrocarbons are processed in metallic equipment which have been previously boronized, that coke formation and deposition which is commonly experienced at high temperatures can be minimized if not totally eliminated. The compositions utilized for this purpose are comprised of boron or boron compounds contained in an organic solvent or carrier together with specific activating materials.

Reid, D. K.

1985-11-26

285

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

286

Preparation of Boron Nitride Fibers Using Hydrated Cellulose. Part 3. Nitriding Hydrated Cellulose Fibers Impregnated with Boric Acid  

Microsoft Academic Search

The effect of preliminary heat treatment (PHT) for hydrated cellulose fibers impregnated with boric acid on the composition and structure of nitrided products is studied. Subsequent nitriding after PHT in helium leads to formation of carbon fibers coated with boron nitride, but after PHT in air there is formation of hexagonal and rhombohedral boron nitride powder. Data obtained are compared

Alexander V. Kurdyumov; N. F. Ostrovskaya; V. M. Vereshchaka

2001-01-01

287

Effect of chemical composition of wurtzitelike boron nitride on the properties of polycrystalline Geksanit-R sinterings  

Microsoft Academic Search

on tools made from such sinterings their cutting elements crack and crumble. Now the starting material in the production of Geksanit-R is wurtzitelike boron nitride (BNw), which forms as a result of a phase transformation of the graphitelike modification of boron nitride (BNg) during shock compression. In this connection, the work described below was undertaken with the aim of studying

L. E. Pechentkovskaya

1978-01-01

288

Boron Fullerenes: An Electronic Structure Study  

Microsoft Academic Search

Using ab initio calculations, we study electronic structure and frequency modes of B80, a member of boron fullerene family made from boron isomorphs of carbon fullerenes with additional atoms in the centers of hexagons. We also investigate geometrical and electronic structural properties of double-rings with various diameters, which are important as building blocks of boron nanotubes, and as the most

Arta Sadrzadeh; Olga Pupysheva; Ihsan Boustani; Boris Yakobson

2008-01-01

289

BORON IS REQUIRED FOR ZEBRAFISH EMBRYOGENESIS  

Microsoft Academic Search

Boron is the only element known to be essential for plants, but only circumstantial evidence for essentiality exists in animals. We report here that boron is essential for the embryonic development of zebrafish (Danio rerio). Zebrafish were maintained in water with a boron concentration of 0.1 ?mol l-1 or supplemented to a concentration of 45 ?mol l-1 using ultrapure boric

RUBY I. ROWE; CURTIS D. ECKHERT

290

Boron removal from geothermal waters by electrocoagulation  

Microsoft Academic Search

Most of the geothermal waters in Turkey contain extremely high concentration of boron when they are used for irrigation. The use of geothermal waters for irrigation can results in excess amount deposition of boron in soil. On the other hand, a minimal boron concentration is required for irrigational waters. In this study, electrocoagulation (EC) was selected as a treatment process

A. Erdem Yilmaz; Recep Boncukcuo?lu; M. Muhtar Kocakerim; M. Tolga Yilmaz; Cihan Paluluo?lu

2008-01-01

291

Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles.  

PubMed

The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer. PMID:24738731

Heyer, Steffen; Janssen, Wiebke; Turner, Stuart; Lu, Ying-Gang; Yeap, Weng Siang; Verbeeck, Jo; Haenen, Ken; Krueger, Anke

2014-06-24

292

Graphene on hexagonal boron nitride.  

PubMed

The field of graphene research has developed rapidly since its first isolation by mechanical exfoliation in 2004. Due to the relativistic Dirac nature of its charge carriers, graphene is both a promising material for next-generation electronic devices and a convenient low-energy testbed for intrinsically high-energy physical phenomena. Both of these research branches require the facile fabrication of clean graphene devices so as not to obscure its intrinsic physical properties. Hexagonal boron nitride has emerged as a promising substrate for graphene devices as it is insulating, atomically flat and provides a clean charge environment for the graphene. Additionally, the interaction between graphene and boron nitride provides a path for the study of new physical phenomena not present in bare graphene devices. This review focuses on recent advancements in the study of graphene on hexagonal boron nitride devices from the perspective of scanning tunneling microscopy with highlights of some important results from electrical transport measurements. PMID:24994551

Yankowitz, Matthew; Xue, Jiamin; LeRoy, B J

2014-07-30

293

Boron doping a semiconductor particle  

SciTech Connect

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

294

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

295

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

296

Hair radioactivity as a measure of exposure to radioisotopes  

NASA Technical Reports Server (NTRS)

Since many radioisotopes accumulate in hair, this tropism was investigated by comparing the radioactivity of shaved with plucked hair collected from rats at various time intervals up to 24 hrs after intravenous injection of the ecologically important radioisotopes, iodine-131, manganese-54, strontium-85, and zinc-65. The plucked hair includes the hair follicles where biochemical transformations are taking place. The data indicate a slight surge of each radioisotpe into the hair immediately after injection, a variation of content of each radionuclide in the hair, and a greater accumulation of radioactivity in plucked than in shaved hair. These results have application not only to hair as a measure of exposure to radioisotopes, but also to tissue damage and repair at the hair follicle.

Strain, W. H.; Pories, W. J.; Fratianne, R. B.; Flynn, A.

1972-01-01

297

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

298

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

299

Oak Ridge Isotope Products and Services - Current and Expected Supply and Demand  

Microsoft Academic Search

Oak Ridge National Laboratory (ORNL) has been a major center of isotope production research, development, and distribution for over 50 years. Currently, the major isotope production activities include (1) the production of transuranium element radioisotopes, including 252 Cf; (2) the production of;\\u000amedical and industrial radioisotopes; (3) maintenance and expansion of the capabilities for production of enriched stable isotopes; and,

W. S. Aaron; C. W. Alexander; R. L. Cline; E. D. Collins; J. A. Klein; Knauer J. B. Jr; S. Mirzadeh

1999-01-01

300

Preparation of Boron-Substituted Carboranes by Boron Insertion Reactions.  

National Technical Information Service (NTIS)

The boron insertion reaction of Hawthorne was employed in preparing 3-fluoro-, 3-bromo- and 3-diphenylamino-o-carborane. This reaction was further extended to the m-carborane system to produce 2-fluoro- and 2-diphenylamino-m-carborane. 3-Fluoro-o-carboran...

J. S. Roscoe S. Kongpricha S. Papetti

1969-01-01

301

Study of Acute Renal Insufficiency and Chronic Renal Insufficiency Using Radioisotopes.  

National Technical Information Service (NTIS)

Radioisotopic renal function tests are of assistance to diagnose and follow-up the course of renal insufficiency. The radioisotopic renogram is useful in assessing the response to therapy of child obstructive uropathies and evaluating renal transplant fun...

C. Raynaud

1976-01-01

302

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

303

Problems of designing radioisotope thermoelectric power generators with a service life of decades for use in outer space exploration vehicles  

NASA Astrophysics Data System (ADS)

The present work deals with the feasibility of developing a radioisotope thermoelectric power generator (RTPG) capable of operating unattended in outer space over a period of several decades, among other things, on the basis of chemical compounds that occur in meteoric matter. The possibilities for solving problems related to the production of three-dimensional materials and to thermoelement interconnections are discussed. The implementation of nanotechnology will allow one to achieve an increase in the efficiency of a RTPG by 15% and higher.

Prilepo, Yu. P.; Pustovalov, A. A.; Sinyavskiy, V. V.; Sudak, N. M.; Yatsenko, O. B.

2012-12-01

304

Mapping of chromosome regions conferring boron toxicity tolerance in barley (Hordeum vulgare L.)  

Microsoft Academic Search

Boron toxicity has been recognised as an important problem limiting production in the low-rainfall regions of southern Australia,\\u000a West Asia and North Africa. Genetic variation for boron toxicity tolerance in barley has been characterised but the mode of\\u000a inheritance and the location of genes controlling tolerance were not previously known. A population of 150 doubled-haploid\\u000a lines from a cross between

S. P. Jefferies; A. R. Barr; A. Karakousis; J. M. Kretschmer; S. Manning; K. J. Chalmers; J. C. Nelson; A. K. M. R. Islam; P. Langridge

1999-01-01

305

Enantioselective Redox-Relay Oxidative Heck Arylations of Acyclic Alkenyl Alcohols using Boronic Acids  

PubMed Central

A general, highly selective asymmetric redox-relay oxidative Heck reaction using achiral or racemic acyclic alkenols and boronic acid derivatives is reported. This reaction delivers remotely functionalized arylated carbonyl products from acyclic alkenol substrates, with excellent enantioselectivity under mild conditions, bearing a range of useful functionality. A preliminary mechanistic investigation suggests that the regioselectivity of the initial migratory insertion is highly dependent on the electronic nature of the boronic acid and more subtle electronic effects of the alkenyl alcohol.

Mei, Tian-Sheng; Werner, Erik W.; Burckle, Alexander J.; Sigman, Matthew S.

2013-01-01

306

Aligned single crystal boron nanowires  

Microsoft Academic Search

The well aligned boron nanowires (BNWs) with single crystalline structure were successfully prepared by using nanochannel-Al2O3 as a substrate and a chemical vapor deposition process. The diameter and length of BNWs were around of 40 nm and several micrometers, respectively. The formation of single crystal BNWs has been conceptually interpreted.

Q. Yang; J Sha; J Xu; Y. J Ji; X. Y Ma; J. J Niu; H. Q Hua; D. R Yang

2003-01-01

307

Reactions of boron with soils  

Microsoft Academic Search

Boron is an essential micronutrient for plants, but the range between deficient and toxic B concentration is smaller than for any other nutrient element. Plants respond directly to the activity of B in soil solution and only indirectly to B adsorbed on soil constituents. Soil factors affecting availability of B to plants are: pH, texture, moisture, temperature, organic matter and

Sabine Goldberg

1997-01-01

308

Boron in plant cell walls  

Microsoft Academic Search

Boron is an essential element for higher plants, yet the primary functions remain unclear. In intact tissues of higher plants, this element occurs as both water soluble and water insoluble forms. In this review, the intracellular localisation of B and possible function of B in cell walls of higher plants are discussed. The majority of the water soluble B seems

Toru Matoh

1997-01-01

309

Method of separating boron isotopes  

DOEpatents

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

Jensen, R.J.; Thorne, J.M.; Cluff, C.L.

1981-01-23

310

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

311

The Kinetics of Boron Transfer in Slag Refining of Silicon  

NASA Astrophysics Data System (ADS)

Slag refining is one of the few metallurgical methods for efficient removal of boron from silicon. In industrial slag refining for production of silicon for photovoltaic applications, the relationship between the slag composition and the mass transfer rate of boron from metal to slag is of great importance. The kinetics of boron removal from liquid silicon during slag refining has been investigated in the present work by means of several small-scale experimental series at temperatures between 1,600C and 1,650C. Slag and metal, in batch weights of 30 g, were heated together in a graphite crucible placed in a resistance-heated tube furnace. The slags were produced from powdered SiO2, CaO, and MgO. The oxides applied were of high purity. Experiments were carried out at slag-to-metal ratios of 1 or 2, where the silicon initially contained approximately 250 ppm boron. Metal-slag mass transfer coefficients were calculated based on chemical analyses of the silicon and ranged from 1.7 ?m/s for slag consisting of equal amounts of SiO2 and CaO by weight, to 4.3 ?m/s for a 40%-40%-20% SiO2-CaO-MgO slag.

Krystad, Egil; Tang, Kai; Tranell, Gabriella

2012-08-01

312

A detailed examination of boronic aciddiol complexation  

Microsoft Academic Search

Boronic acids bind with compounds containing diol moieties with high affinity through reversible boronate formation. However, the conditions that foster tight binding between the diol and the boronic acid are not well understood. Also, due to the multiple ionic states of both the boronic acid and boronate ester, the equilibrium constants reported in the literature have not always been strictly

Greg Springsteen; Binghe Wang

2002-01-01

313

Use of Radioisotopes in Laboratory Energy Assimilation Investigations with Daphnia  

Microsoft Academic Search

IN most zooplankton-phytoplankton grazing studies, assimilation by the grazers (which is the true measure of energy transfer in a food web) has been inferred indirectly from measurements of phytoplankton cell concentration and zooplankton filtration, egestion, growth, and respiration rates. A more rapid and critical method of assessing zooplankton assimilation is to measure it directly with a radioisotope tracer and translate

L. F. Small

1962-01-01

314

Application of radioisotope tracing technique in the agricultural machinery research.  

National Technical Information Service (NTIS)

The radioisotope tracing technique with (sup 60)Co and (sup 3)H radionuclides was used in the process of shelling, clearing and drying when agricultural machines were utilized. The velocity distribution and travelling time of cereal from inlet to the outl...

S. Wang C. Wang X. Hao Y. An J. Li

1988-01-01

315

Radioisotope Power Generator (RPG) 25F Shock Isolation Studies.  

National Technical Information Service (NTIS)

A study was undertaken to develop a graphical method for designing shock isolators for the Sentinel 25F Radioisotope Power Generator (RPG). A mathematical model of the RPG was developed empirically from vibration-response data and used to predict the shoc...

R. T. Williams

1974-01-01

316

An Advanced Turbo-Brayton Converter for Radioisotope Power Systems  

Microsoft Academic Search

Past work has shown that Brayton power converters are an attractive option for high power, long-duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo-Brayton converter under NASA's Prometheus Program.

Mark V. Zagarola; Michael G. Izenson; Jeffrey J. Breedlove; George M. O'Connor; Andrew C. Ketchum; Richard L. Jetley; James K. Simons

2005-01-01

317

Benefit of Small Radioisotope Power Systems for NASA Exploration Missions  

Microsoft Academic Search

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,

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

2005-01-01

318

Enabling Solar System Exploration with Small Radioisotope Power Systems  

Microsoft Academic Search

The increased use of smaller spacecraft over the last decade, in combination with studies of potential science applications, has suggested that a wide range of low power missions and applications could be enabled by a new generation of conceptual small radioisotope power systems with power levels in the range of 20 mW to a few 10's of watts. Such systems

R. D. Abelson; T. S. Balint; H. Noravian; J. E. Randolph; C. Satter; G. R. Schmidt; J. H. Shirley

2005-01-01

319

Exp 82 Sr-- Exp 82 Rb Radioisotope Generator.  

National Technical Information Service (NTIS)

An improved exp 82 Sr- exp 82 Rb radioisotope generator system, based upon the complexing ion exchange resin Chelex-100, has been developed. Columns of this material can be easily and rapidly milked, and the Rb-Sr separation factor for a fresh generator w...

P. M. Grant B. R. Erdal H. A. O'Brien

1976-01-01

320

Feeding Rate of Carp Estimated by a Radioisotopic Method  

Microsoft Academic Search

The feeding rate was estimated for yearling carp living in a small lake contaminated with low-level radioactive wastes. The amount of Cs that must be ingested to maintain the equilibrium body burden of the carp was calculated from measured values for body burden, biological elimination rates, and assimilation factors. The radioisotope was ingested by the fish as an integral part

N. R. Kevern

1966-01-01

321

Power performance of US space radioisotope thermoelectric generators  

Microsoft Academic Search

Since 1961, the United States has flown 41 radioisotope thermoelectric generators (RTGs) and one reactor to provide power for 25 space power systems. Thirty-eight of these nuclear power sources on 22 space systems are still in space or on other planetary bodies. This paper summarizes the design and power performance of each of the basic RTG types that have been

Gary L. Bennett; E. A. Skrabek

1996-01-01

322

Reentry thermal testing of light-weight radioisotope heater units  

SciTech Connect

Two Light-Weight Radioisotope Heater Units (LWRHU) were exposed to thermal ramps simulating atmospheric reentry. The helium release rates were measured during each test and modeled after simple diffusion theory. The reentry pulses did not result in swelling of the claddings or degradation of fuel pellets.

Peterson, D.E.; Starzynski, J.S.

1982-03-01

323

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

PubMed

Boron is ubiquitously present in soils and water. Associated with pectin it is essential for vascular plants as a component of cell walls, and it stabilizes cell membranes. It is required for the growth of pollen tubes and is involved in membrane transport, stimulating H(+)-pumping ATPase activity and K+ uptake. However, a high boron concentration in the soils is toxic to plants and some boronated derivatives are used as herbicides. An absolute requirement for boron has not been definitively demonstrated in animals and humans. However, experiments with boron supplementation or deprivation show that boron is involved in calcium and bone metabolism, and its effects are more marked when other nutrients (cholecalciferol, magnesium) are deficient. Boron supplementation increases the serum concentration of 17 beta-estradiol and testosterone but boron excess has toxic effects on reproductive function. Boron may be involved in cerebral function via its effects on the transport across membranes. It affects the synthesis of the extracellular matrix and is beneficial in wound healing. Usual dietary boron consumption in humans is 1-2 mg/day for adults. As boron has been shown to have biological activity, research into the chemistry of boronated compounds has increased. Boronated compounds have been shown to be potent anti-osteoporotic, anti-inflammatory, hypolipemic, anti-coagulant and anti-neoplastic agents both in vitro and in vivo in animals. PMID:9638606

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

1998-03-01

324

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

325

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.

2012-01-01

326

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

327

Boron Arsenide and Boron Phosphide for High Temperature and Luminescent Devices.  

National Technical Information Service (NTIS)

The crystal growth of boron arsenide and boron phosphide in the form of bulk crystals and epitaxial layers on suitable substrates is discussed. The physical, chemical, and electrical properties of the crystals and epitaxial layers are examined. Bulk cryst...

T. L. Chu

1975-01-01

328

Longitudinal Splitting of Boron Nitride Nanotubes for the Facile Synthesis of High Quality Boron Nitride Nanoribbons.  

National Technical Information Service (NTIS)

Boron nitride nanoribbons (BNNRs), the boron nitride structural equivalent of graphene nanoribbons (GNRs), are predicted to possess unique electronic and magnetic properties. We report the synthesis of BNNRs through the potassium-intercalation-induced lon...

A. Sinitskii A. L. Gibb K. J. Erickson M. Rousseas N. Alem

2011-01-01

329

Final design review of boron carbide safety rod  

SciTech Connect

The object of this paper discusses the design review of the boron carbide safety rod for the Westinghouse Savannah River Company. This paper reviewed information presented by personnel of the Savannah River Laboratory (SRL) Equipment Engineering Section, SRL Materials Technology Section and Reactor Materials Engineering and Technology. From this report, views, opinions and recommendations were made on the safety rod from materials testing to production.

Lutz, R.N.

1991-09-24

330

Defect behavior in electron-irradiated boron- and gallium-doped silicon  

NASA Technical Reports Server (NTRS)

Production and anneal of defects in electron-irradiated, float-zone silicon solar cells were studied by DLTS. In boron- and gallium-doped, n+-p cells, dominant defects were due to the divacancy, carbon interstitial, and carbon complex. Results suggest that the DLTS peak normally ascribed to carbon complexes also involves gallium. For gallium- and, to a lesser extent, boron-doped samples, damaged lifetime shows substantial recovery only when the carbon-complex peak has annealed out at 400 C. In boron-doped, n+-p-p+ cells, a minority carrier trap (E1) was also observed by DLTS in cells with a boron p+, but not in those with an aluminum p+ back. A level at Ev + 0.31 eV appeared upon 150 C annealing (E1 out) in both p+ back types of samples.

Drevinsky, P. J.; Deangelis, H. M.

1982-01-01

331

Boron-toxicity tolerance in barley arising from efflux transporter amplification.  

PubMed

Both limiting and toxic soil concentrations of the essential micronutrient boron represent major limitations to crop production worldwide. We identified Bot1, a BOR1 ortholog, as the gene responsible for the superior boron-toxicity tolerance of the Algerian barley landrace Sahara 3771 (Sahara). Bot1 was located at the tolerance locus by high-resolution mapping. Compared to intolerant genotypes, Sahara contains about four times as many Bot1 gene copies, produces substantially more Bot1 transcript, and encodes a Bot1 protein with a higher capacity to provide tolerance in yeast. Bot1 transcript levels identified in barley tissues are consistent with a role in limiting the net entry of boron into the root and in the disposal of boron from leaves via hydathode guttation. PMID:18048688

Sutton, Tim; Baumann, Ute; Hayes, Julie; Collins, Nicholas C; Shi, Bu-Jun; Schnurbusch, Thorsten; Hay, Alison; Mayo, Gwenda; Pallotta, Margaret; Tester, Mark; Langridge, Peter

2007-11-30

332

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

333

Modifying Hydroxyapatite Nucleating Peptides to Form Novel Boron Ceramics.  

National Technical Information Service (NTIS)

Reported are efforts to modify the Hydroxyapatite nucleating peptide (HANP) isolated from Corynebacterium matruchotti to nucleate boron as opposed to calcium. The literature reports that boron-binding proteins utilize a His and Ser complex to bind boron i...

R. E. Stone

2003-01-01

334

Method of Joining Boron Nitride to a Refractory.  

National Technical Information Service (NTIS)

Boron nitride is joined to a refractory at high temperatures by coating a surface of the boron nitride with a mixture of paintable consistency of molybdenum disilicide and polyisobutyl methacrylate in an organic solvent, allowing the coated boron nitride ...

S. DuBuske

1981-01-01

335

Helium diffusion in irradiated boron carbide. [LMFBR  

SciTech Connect

Boron carbide has been internationally adopted as the neutron absorber material in the control and safety rods of large fast breeder reactors. Its relatively large neutron capture cross section at high neutron energies provides sufficient reactivity worth with a minimum of core space. In addition, the commercial availability of boron carbide makes it attractive from a fabrication standpoint. Instrumented irradiation experiments in EBR-II have provided continuous helium release data on boron carbide at a variety of operating temperatures. Although some microstructural and compositional variations were examined in these experiments most of the boron carbide was prototypic of that used in the Fast Flux Test Facility. The density of the boron carbide pellets was approximately 92% of theoretical. The boron carbide pellets were approximately 1.0 cm in diameter and possessed average grain sizes that varied from 8 to 30 ..mu..m. Pellet centerline temperatures were continually measured during the irradiation experiments.

Hollenberg, G.W.

1981-03-01

336

Study of boron behaviour in two Spanish coal combustion power plants.  

PubMed

A full-scale field study was carried out at two Spanish coal-fired power plants equipped with electrostatic precipitator (ESP) and wet flue gas desulfurisation (FGD) systems to investigate the distribution of boron in coals, solid by-products, wastewater streams and flue gases. The results were obtained from the simultaneous sampling of solid, liquid and gaseous streams and their subsequent analysis in two different laboratories for purposes of comparison. Although the final aim of this study was to evaluate the partitioning of boron in a (co-)combustion power plant, special attention was paid to the analytical procedure for boron determination. A sample preparation procedure was optimised for coal and combustion by-products to overcome some specific shortcomings of the currently used acid digestion methods. In addition boron mass balances and removal efficiencies in ESP and FGD devices were calculated. Mass balance closures between 83 and 149% were obtained. During coal combustion, 95% of the incoming boron was collected in the fly ashes. The use of petroleum coke as co-combustible produced a decrease in the removal efficiency of the ESP (87%). Nevertheless, more than 90% of the remaining gaseous boron was eliminated via the FGD in the wastewater discharged from the scrubber, thereby causing environmental problems. PMID:21664037

Ochoa-Gonzlez, Raquel; Cuesta, Aida Fuente; Crdoba, Patricia; Daz-Somoano, Mercedes; Font, Oriol; Lpez-Antn, M Antonia; Querol, Xavier; Martnez-Tarazona, M Rosa; Gimnez, Antonio

2011-10-01

337

Energy Landscape of Fullerene Materials: A Comparison of Boron to Boron Nitride and Carbon  

Microsoft Academic Search

Using the minima hopping global geometry optimization method on the density functional potential energy surface we show that the energy landscape of boron clusters is glasslike. Larger boron clusters have many structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers. The differences

Sandip de; Alexander Willand; Maximilian Amsler; Pascal Pochet; Luigi Genovese; Stefan Goedecker

2011-01-01

338

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

Microsoft Academic Search

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

Danny C. Halverson; Richard L. Landingham

1988-01-01

339

Dietary boron, brain function, and cognitive performance.  

PubMed

Although the trace element boron has yet to be recognized as an essential nutrient for humans, recent data from animal and human studies suggest that boron may be important for mineral metabolism and membrane function. To investigate further the functional role of boron, brain electrophysiology and cognitive performance were assessed in response to dietary manipulation of boron (approximately 0.25 versus approximately 3.25 mg boron/2000 kcal/day) in three studies with healthy older men and women. Within-subject designs were used to assess functional responses in all studies. Spectral analysis of electroencephalographic data showed effects of dietary boron in two of the three studies. When the low boron intake was compared to the high intake, there was a significant (p < 0.05) increase in the proportion of low-frequency activity, and a decrease in the proportion of higher-frequency activity, an effect often observed in response to general malnutrition and heavy metal toxicity. Performance (e.g., response time) on various cognitive and psychomotor tasks also showed an effect of dietary boron. When contrasted with the high boron intake, low dietary boron resulted in significantly poorer performance (p < 0.05) on tasks emphasizing manual dexterity (studies II and III); eye-hand coordination (study II); attention (all studies); perception (study III); encoding and short-term memory (all studies); and long-term memory (study I). Collectively, the data from these three studies indicate that boron may play a role in human brain function and cognitive performance, and provide additional evidence that boron is an essential nutrient for humans. PMID:7889884

Penland, J G

1994-11-01

340

Boron Fullerenes: A First-Principles Study  

Microsoft Academic Search

A family of unusually stable boron cages was identified and examined using first-principles local-density functional method. The structure of the fullerenes is similar to that of the B12 icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms. A connection between the fullerene family and its precursors, boron sheets, is made.

Nevill Gonzalez Szwacki

2008-01-01

341

Boron Fullerenes: A First-Principles Study  

Microsoft Academic Search

A family of unusually stable boron cages was identified and examined using first-principles local-density functional method.\\u000a The structure of the fullerenes is similar to that of the B12 icosahedron and consists of six crossing double-rings. The energetically most stable fullerene is made up of 180 boron atoms.\\u000a A connection between the fullerene family and its precursors, boron sheets, is made.

Nevill Gonzalez Szwacki

2008-01-01

342

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

343

CVD-produced boron filaments  

NASA Technical Reports Server (NTRS)

A technique for producing boron filaments with an average tensile strength of 6.89 GPa has been developed which involves longitudinal splitting of the filament and core (substrate) removal by etching. Splitting is accomplished by a pinch wheel device which continuously splits filaments in lengths of 3.0 m by applying a force to the side of the filament to create a crack which is then propagated along the axis by a gentle sliding action. To facilitate the splitting, a single 10 mil tungsten substrate is used instead of the usual 0.5 mil substrate. A solution of hot 30% hydrogen peroxide is used to remove the core without attacking the boron. An alternative technique is to alter the residual stress by heavily etching the filament. Average strengths in the 4.83-5.52 GPa range have been obtained by etching an 8 mil filament to 4 mil.

Wawner, F. E.; Debolt, H. E.; Suplinskas, R. D.

1980-01-01

344

Boron in Marine Barite: A Potential Proxy for the Boron Isotopic Composition of Seawater  

NASA Astrophysics Data System (ADS)

Paleoceanographic reconstructions of past ocean pH facilitate predictions of the response of ocean chemistry to modern climate change and associated effects on marine ecosystems. Past ocean pH reconstructions rely on the analysis of boron stable isotopic ratios (?11B) in biogenic marine carbonates. The equations used to calculate pH from a measured carbonate ?11B value require an input for the ?11B composition of seawater. Since boron is well mixed throughout the ocean, this value is well-constrained for modern seawater and is thought to be robust for the last ~10 million years given the long residence time of B in the ocean. However, without long-term constraints on seawater ?11B, the accuracy of paleo-pH reconstructions for time periods earlier than ~10 Ma can be called into question. To address this issue, we are exploring the potential use of marine barite as an independent proxy for seawater ?11B. Marine barite forms as an inorganic precipitate in biologically productive regions of the ocean and is highly resistant to post-depositional dissolution. It has been shown to be a reliable proxy for seawater Sulfate, Sr, Ca, Ra, Selenate and Pb isotopes. We hypothesize that boron can also be incorporated into the barite crystal and that the isotopic signature of B in barite will reflect seawater pH. We will present and discuss the results of a labeling experiment in which barite will be precipitated from parent seawater solutions with differing ?11B. Potential incorporation mechanisms and fractionation effects will also be addressed.

Chrystal, A.; Paytan, A.

2012-12-01

345

Lattice constants of boron carbides  

Microsoft Academic Search

In this paper, the lattice constants of boron carbides are determined by powder X-ray diffraction for samples with compositions between about 7.7 and 20.5 at.% carbon. The boundaries of the single-phase region are at about 9 at.% carbon and near, but likely somewhat less than 20 at.% carbon. The composition dependence of the lattice constants thus established provides a method

Terry L. Aselage; Ralph G. Tissot

1992-01-01

346

The boron geochemistry of siliceous sponges  

NASA Astrophysics Data System (ADS)

The boron content and isotopic composition (?11B) of marine carbonate organisms can be linked to the pH of the seawater in which they have grown, making carbonates a useful tool for palaeo-seawater pH reconstruction. A study by Furst (1981) documented unusually high boron concentrations in siliceous sponge spicules, in range from hundreds to a thousand ppm. This observation and the potential for preferential incorporation of the tetrahedral borate species into biogenic silica raises the question as to whether the boron chemistry of biogenic silica might also be influenced by seawater pH. We have measured the boron concentration and isotopic composition of siliceous sponges from the Southern Ocean region, with a view to (1) confirming the observations of Furst (1981), (2) assessing the factors that control boron incorporation and isotopic compositions of sponge silica, and (3) investigating the potentially significant role of siliceous sponges in the marine boron cycle. The measured boron concentrations in a diverse range of both demosponge and hexactinellid sponges confirm the high boron concentrations previously reported. The boron isotope compositions of these sponges vary from around +2 to +25 and greatly exceed the range in marine carbonates. This isotopic variation is inconsistent with seawater pH control but is correlated with ambient seawater silicon concentration, in a manner that suggests a link to silicon uptake kinetics and demand by sponges.

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

2009-12-01

347

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.

Lhrs, Hanna, E-mail: hanna.luehrs@uni-bremen.de [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany)] [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany); Fischer, Reinhard X. [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany)] [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany); Schneider, Hartmut [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany) [Universitt Bremen, FB 5 Geowissenschaften, Klagenfurter Strae, D-28359 Bremen (Germany); Universitt Kln, Institut fr Kristallographie, Greinstrae 6, D-50939 Klm (Germany)

2012-12-15

348

Optical properties of boron-doped diamond  

NASA Astrophysics Data System (ADS)

We report optical reflectivity study on pure and boron-doped diamond films grown by a hot-filament chemical vapor deposition method. The study reveals the formation of an impurity band close to the top of the valence band upon boron doping. A schematic picture for the evolution of the electronic structure with boron doping was drawn based on the experimental observation. The study also reveals that the boron doping induces local lattice distortion, which brings an infrared-forbidden phonon mode at 1330cm-1 activated in the doped sample. The antiresonance characteristic of the mode in conductivity spectrum evidences the very strong coupling between electrons and this phonon mode.

Wu, Dan; Ma, Y. C.; Wang, Z. L.; Luo, Q.; Gu, C. Z.; Wang, N. L.; Li, C. Y.; Lu, X. Y.; Jin, Z. S.

2006-01-01

349

Boron nitride nanosystems of regular geometry  

NASA Astrophysics Data System (ADS)

The explicit expressions in term of B-N bond length are obtained for atomic site coordinates and intersite distances in regular boron nitride nanotubes and fullerenes. The radii of single-walled BN nanotubes and single-shelled BN fullerenes are estimated, and their most stable associations in form of double-walled nanotubes and double-shelled fullerenes are predicted. The differences between radii of regular boron nitride fullerenes with indexes of (n + 3) and (n) are almost equal to the interlayer distance in layered boron nitride structures. Description made for the boron nitride nanosystems of regular geometries may serve as basis for further ground state and electron structure calculations.

Chkhartishvili, Levan

2009-06-01

350

Boronization in D3-D  

NASA Astrophysics Data System (ADS)

A thin boron film was applied to the D3-D tokamak plasma facing surfaces to reduce impurity influx, particularly oxygen and carbon. A direct result of this surface modification was the observation of a regime of very high energy confinement, VH-mode, with confinement times from 1.5 to 2 times greater than predicted by H-mode scaling relation for the same set of parameters. VH-mode discharges are characterized by low ohmic target densities, low edge neutral pressure, and reduced cycling. These conditions have reduced the collisionality, (nu)*, in the edge region producing a higher edge pressure gradient and a significant bootstrap current, up to 30 percent of the total current. We will describe the edge plasma properties after boronization including reductions in recycling inferred from measurements of (tau)(sub p)*. In particular we will discuss the edge plasma conditions necessary for access to VH-mode including the boronization process and properties of the deposited film.

Jackson, G. L.; Burrell, K. H.; Deboo, J. C.; Greenfield, C. M.; Groebner, R. J.; Hodapp, T.; Kellman, A. G.; Lee, R.; Lippman, S. I.; Phillips, J.

1992-05-01

351

Energy landscape of fullerene materials: a comparison of boron to boron nitride and carbon.  

PubMed

Using the minima hopping global geometry optimization method on the density functional potential energy surface we show that the energy landscape of boron clusters is glasslike. Larger boron clusters have many structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers. The differences in the potential energy landscape explain why carbon and boron nitride systems are found in nature whereas pure boron fullerenes have not been found. We thus present a methodology which can make predictions on the feasibility of the synthesis of new nanostructures. PMID:21702613

De, Sandip; Willand, Alexander; Amsler, Maximilian; Pochet, Pascal; Genovese, Luigi; Goedecker, Stefan

2011-06-01

352

Californium252: a remarkable versatile radioisotope  

Microsoft Academic Search

A product of the nuclear age, Californium-252 (²⁵²Cf) has found many applications in medicine, scientific research, industry, and nuclear science education. Californium-252 is unique as a neutron source in that it provides a highly concentrated flux and extremely reliable neutron spectrum from a very small assembly. During the past 40 years, ²⁵²Cf has been applied with great success to cancer

I. W. Osborne-Lee; C. W. Alexander

1995-01-01

353

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

2009-10-06

354

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

355

Outer Planet Exploration with Advanced Radioisotope Electric Propulsion  

NASA Technical Reports Server (NTRS)

In response to a request by the NASA Deep Space Exploration Technology Program, NASA Glenn Research Center conducted a study to identify advanced technology options to perform a Pluto/Kuiper mission without depending on a 2004 Jupiter Gravity Assist, but still arriving before 2020. A concept using a direct trajectory with small, sub-kilowatt ion thrusters and Stirling radioisotope power systems was shown to allow the same or smaller launch vehicle class as the chemical 2004 baseline and allow a launch slip and still flyby in the 2014 to 2020 timeframe. With this promising result the study was expanded to use a radioisotope power source for small electrically propelled orbiter spacecraft for outer planet targets such as Uranus, Neptune, and Pluto.

Oleson, Steven; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey; Benson, Scott; McAdams, Jim; Ostdiek, Paul

2002-01-01

356

Safety status of space radioisotope and reactor power sources  

NASA Technical Reports Server (NTRS)

The current overall safety criterion for both radioisotope and reactor power sources is containment or immobilization in the case of a reentry accident. In addition, reactors are designed to remain subcritical under conditions of land impact or water immersion. A very extensive safety test and analysis program was completed on the radioisotope thermoelectric generators (RTGs) in use on the Galileo spacecraft and planned for use on the Ulysses spacecraft. The results of this work show that the RTGs will pose little or no risk for any credible accident. The SP-100 space nuclear reactor program has begun addressing its safety criteria, and the design is planned to be such as to ensure meeting the various safety criteria. Preliminary mission risk analyses on SP-100 show the expected value population dose from postulated accidents on the reference mission to be very small. It is concluded that the current US nuclear power sources are the safest flown.

Bennett, Gary L.

1990-01-01

357

Radioisotopic energy conversion system (RECS): A new radioisotopic power cell, based on nuclear, atomic, and radiation transport principles  

NASA Astrophysics Data System (ADS)

The topic of this thesis is the development of the Radioisotope Energy Conversion System (RECS) in a project which is utilizing analytical computational assisted design and some experimental Research in the investigation of fluorescers and effective transducers with the appropriate energy range choice for the conversion of energy. It is desirable to increase the efficiency in electrical power from the raw kinetic power available from the radioactive material within radioisotope power generators. A major step in this direction is the development and use of Radioisotope Energy Conversion Systems to supplement and ideally replace Radioactive Thermal Generators (RTG). It is possible to achieve electrical conversion efficiencies exceeding 25% for RECS power devices compared to only 9 percent efficiency for RTG's. The theoretical basis with existent materials for the potential achievability of efficiencies above 25% is documented within this thesis. The fundamental RECS consists of a radioisotope radiative source (C1), a mediating fluorescent gas (C2) which readily absorbs energy from the beta particles (or alpha's) and subsequently emits blue or UV photons, photovoltaic cells (C3) to convert the blue and UV photons into electrical energy [2], and electrical circuitry (C4). Solid State inspired component (C3), due to its theoretical (and attainable) high efficiency, is a large step ahead of the RTG design concept. The radioisotope flux source produces the beta(-) particles or alpha particles. Geometrically, presently, we prefer to have the ambient fluorescent gas surround the radioisotope flux source. Our fluorescer shall be a gas such as Krypton. Our specifically wide band-gap photovoltaic cells shall have gap energies which are slightly less than that of UV photons produced by the fluorescing gas. Diamond and Aluminum Nitride sample materials are good potential choices for photovoltaic cells, as is explained here in. Out of the material examples discussed, the highest electric power to mass ratio is found to be readily attainable with strontium-90 as the radiative source. Krypton-85 is indisputably the most efficient in RECS devices. In the conclusion in chapter VI, suggestions are given on acceptable ways of containing krypton-85 and providing sufficient shielding on deep space probes destined to use krypton-85 powered 'batteries'.

Steinfelds, Eric Victor

358

An Advanced Turbo-Brayton Converter for Radioisotope Power Systems  

Microsoft Academic Search

Past work has shown that Brayton power converters are an attractive option for high power, long-duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo-Brayton converter under NASAs Prometheus Program.

Mark V. Zagarola; Michael G. Izenson; Jeffrey J. Breedlove; George M. OConnor; Andrew C. Ketchum; Richard L. Jetley; James K. Simons

2005-01-01

359

Radioisotope thermoelectric generator transportation system subsystem 143 software development plan  

NASA Astrophysics Data System (ADS)

This plan describes the activities to be performed and the controls to be applied to the process of specifying, developing, and qualifying the data acquisition software for the Radioisotope Thermoelectric Generator (RTG) Transportation System Subsystem 143 Instrumentation and Data Acquisition System (IDAS). This plan will serve as a software quality assurance plan, a verification and validation (V and V) plan, and a configuration management plan.

King, D. A.

1994-11-01

360

Synthesis of vertically aligned boron nitride nanosheets using CVD method  

SciTech Connect

Highlights: ? The synthesized boron nitride nanosheets (BNNSs) are vertically aligned and very thin. ? No electrical field is applied in the CVD process. ? The thin BNNSs show a low turn-on field of 6.5 V ?m{sup ?1} and emit strong UV light. -- Abstract: Boron nitride nanosheets (BNNSs) protruding from boron nitride (BN) films were synthesized on silicon substrates by chemical vapor deposition technique from a gas mixture of BCl{sub 3}NH{sub 3}H{sub 2}N{sub 2}. Parts of the as-grown nanosheets were vertically aligned on the BN films. The morphology and structure of the synthesized BNNSs were characterized by scanning electron microscopy, transmission electron microscopy, and Fourier transformation infrared spectroscopy. The chemical composition was studied by energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Cathodoluminescence spectra revealed that the product emitted strong UV light with a broad band ranging from 250 to 400 nm. Field-emission characteristic of the product shows a low turn-on field of 6.5 V ?m{sup ?1}.

Zhang, Chao [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China)] [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China); Hao, Xiaopeng, E-mail: xphao@sdu.edu.cn [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China)] [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China); Wu, Yongzhong, E-mail: wuyz@sdu.edu.cn [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China)] [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China); Du, Miao [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China)] [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China)

2012-09-15

361

Boron enolate chemistry toward the syntheses of polyketide stereotetrads.  

PubMed

In 1976 Mukaiyama published a paper that was to make a major impact on the development of the aldol reaction in the future. Mild enolate formation by treatment of a ketone with dibutylboron triflate in the presence of a tertiary amine generates a relatively stable boron enolate, which can subsequently react with an aldehyde to give the cross-aldol product in good yields. This reaction has become a reliable tool for the practicing synthetic chemist. Nearly 10000 polyketides are known, and of these about 600 contain the tripropionate unit with a stereotetrad, four contiguous stereocenters with alternating methyl and hydroxyl substituents in the main chain. The versatility of the boron enolate aldol reaction is showcased with selected applications in the synthesis of these structural motifs. PMID:24420331

Koskinen, Ari M P

2014-02-01

362

Stimulus sensitive gel with radioisotope and methods of making  

DOEpatents

The present invention is a thermally reversible stimulus-sensitive gel or gelling copolymer radioisotope carrier that is a linear random copolymer of an [meth]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum gelling molecular weight cutoff. Addition of a biodegradable backbone and/or a therapeutic agent imparts further utility. The method of the present invention for making a thermally reversible stimulus-sensitive gelling copolymer radionuclcide carrier has the steps of: (a) mixing a stimulus-sensitive reversible gelling copolymer with an aqueous solvent as a stimulus-sensitive reversible gelling solution; and (b) mixing a radioisotope with said stimulus-sensitive reversible gelling solution as said radioisotope carrier. The gel is enhanced by either combining it with a biodegradable backbone and/or a therapeutic agent in a gelling solution made by mixing the copolymer with an aqueous solvent.

Weller, Richard E. (Selah, WA) [Selah, WA; Lind, Michael A. (Kent, WA) [Kent, WA; Fisher, Darrell R. (Richland, WA) [Richland, WA; Gutowska, Anna (Richland, WA) [Richland, WA; Campbell, Allison A. (Kennewick, WA) [Kennewick, WA

2001-10-02

363

Radioisotope Power: A Key Technology for Deep Space Explorations  

NASA Technical Reports Server (NTRS)

A Radioisotope Power System (RPS) generates power by converting the heat released from the nuclear decay of radioactive isotopes, such as Plutonium-238 (Pu-238), into electricity. First used in space by the U.S. in 1961, these devices have enabled some of the most challenging and exciting space missions in history, including the Pioneer and Voyager probes to the outer solar system; the Apollo lunar surface experiments; the Viking landers; the Ulysses polar orbital mission about the Sun; the Galileo mission to Jupiter; the Cassini mission orbiting Saturn; and the recently launched New Horizons mission to Pluto. Radioisotopes have also served as a versatile heat source for moderating equipment thermal environments on these and many other missions, including the Mars exploration rovers, Spirit and Opportunity. The key advantage of RPS is its ability to operate continuously, independent of orientation and distance relative to the Sun. Radioisotope systems are long-lived, rugged, compact, highly reliable, and relatively insensitive to radiation and other environmental effects. As such, they are ideally suited for missions involving long-lived, autonomous operations in the extreme conditions of space and other planetary bodies. This paper reviews the history of RPS for the U.S. space program. It also describes current development of a new Stirling cycle-based generator that will greatly expand the application of nuclear-powered missions in the future.

Schmidt, George R.; Sutliff, Thomas J.; Duddzinski, Leonard

2009-01-01

364

Radioisotope Power: A Key Technology for Deep Space Exploration  

NASA Technical Reports Server (NTRS)

A Radioisotope Power System (RPS) generates power by converting the heat released from the nuclear decay of radioactive isotopes, such as Plutonium-238 (Pu-238), into electricity. First used in space by the U.S. in 1961, these devices have enabled some of the most challenging and exciting space missions in history, including the Pioneer and Voyager probes to the outer solar system; the Apollo lunar surface experiments; the Viking landers; the Ulysses polar orbital mission about the Sun; the Galileo mission to Jupiter; the Cassini mission orbiting Saturn; and the recently launched New Horizons mission to Pluto. Radioisotopes have also served as a versatile heat source for moderating equipment thermal environments on these and many other missions, including the Mars exploration rovers, Spirit and Opportunity. The key advantage of RPS is its ability to operate continuously, independent of orientation and distance relative to the Sun. Radioisotope systems are long-lived, rugged, compact, highly reliable, and relatively insensitive to radiation and other environmental effects. As such, they are ideally suited for missions involving long-lived, autonomous operations in the extreme conditions of space and other planetary bodies. This paper reviews the history of RPS for the U.S. space program. It also describes current development of a new Stirling cycle-based generator that will greatly expand the application of nuclear-powered missions in the future.

Schmidt, George; Sutliff, Tom; Dudzinski, Leonard

2008-01-01

365

Radioisotope Electric Propulsion Centaur Orbiter Spacecraft Design Overview  

NASA Technical Reports Server (NTRS)

Radioisotope electric propulsion (REP) has been shown in past studies to enable missions to outerplanetary bodies including the orbiting of Centaur asteroids. Key to the feasibility for REP missions are long life, low power electric propulsion (EP) devices, low mass radioisotope power systems (RPS) and light spacecraft (S/C) components. In order to determine what are the key parameters for EP devices to perform these REP missions a design study was completed to design an REP S/C to orbit a Centaur in a New Frontiers cost cap. The design shows that an orbiter using several long lived (approximately 200 kg Xenon throughput), low power (approximately 700 W) Hall thrusters teamed with six (150 W each) Advanced Stirling Radioisotope Generators (ASRG) can deliver 60 kg of science instruments to a Centaur in 10 yr within the New Frontiers cost cap. Optimal specific impulses for the Hall thrusters were found to be around 2000 sec with thruster efficiencies over 40%. Not only can the REP S/C enable orbiting a Centaur (when compared to an all chemical mission only capable of flybys) but the additional power from the REP system can be reused to enhance science and simplify communications.

Oleson, Steve; McGuire, Melissa; Sarver-Verhey, Tim; Juergens, Jeff; Parkey, Tom; Dankanich, John; Fiehler, Doug; Gyekenyesi, John; Hemminger, Joseph; Gilland, Jim; Colozza, Tony; Packard, Tom; Nguyen, Thahn; Schmitz, Paul; Ostdiek, Paul; Gold, Rob; Lisse, Carey; Hibbits, Karl

2009-01-01

366

Combustion characteristics of GAP-coated boron particles and the fuel-rich solid propellant  

SciTech Connect

A process was employed that permits the coating of energetic glycidyl azide polymer (GAP) on the boron surface. Ignition and combustion behavior of single particle pure crystalline boron and GAP-coated boron at atmospheric pressure was studied experimentally by injecting the particles into the stream of hot gaseous environment of a flat-flame burner using premixed propane-oxygen-nitrogen gases. Chopped streak photographic observation was used to measure the ignition and combustion time. The flame temperature was fixed around 2,343 K, but under wider O{sub 2} level range than previous investigations. Measurement results show that GAP coating can shorten boron particle ignition delay time, however, the effect diminishes as the O{sub 2} level in combustion gas decreases. Possible mechanisms based on relevant reactions and heat effects were proposed. Combustion characteristics of fuel-rich solid propellants based on GAP-coated amorphous boron particles and uncoated ones were compared using different techniques such as combustion phenomena observations by a windowed strand burner, quenched propellant surface morphology analysis by scanning electron microscope, and combustion residues size analysis from the quenched particle collection bomb experiments. It was concluded that GAP-coated amorphous-boron-based fuel-rich propellants exhibit more vigorous combustion phenomena, higher burning rates, and a lesser extent of residue agglomeration than the uncoated baseline propellant. Moreover, reaction mechanisms were proposed to elucidate the combustion products obtained in this study.

Shyu, I.M. [Chung Cheng Inst. of Technology, Tashi (Taiwan, Province of China). Dept. of Applied Chemistry] [Chung Cheng Inst. of Technology, Tashi (Taiwan, Province of China). Dept. of Applied Chemistry; Liu, T.K. [Chung Shan Inst. of Science and Technology, Lungtan (Taiwan, Province of China). Chemical System Research Division] [Chung Shan Inst. of Science and Technology, Lungtan (Taiwan, Province of China). Chemical System Research Division

1995-03-01

367

Ferrocenyl-substituted Schiff base complexes of boron: Synthesis, structural, physico-chemical and biochemical aspects  

NASA Astrophysics Data System (ADS)

Biological important complexes of boron(III) derived from 1-acetylferrocenehydrazinecarboxamide (L 1H), 1-acetylferrocenehydrazinecarbothioamide (L 2H) and 1-acetylferrocene carbodithioic acid (L 3H) have been prepared and investigated using a combination of microanalytical analysis, melting point, electronic, IR, 1H NMR and 13C NMR spectral studies, cyclic voltammetry and X-ray powder diffraction studies. Boron isopropoxide interacts with the ligands in 1:1, 1:2 and 1:3 molar ratios (boron:ligand) resulting in the formation of coloured products. On the basis of conductance and spectral evidences, tetrahedral structures for boron(III) complexes have been assigned. The ligands are coordinated to the boron(III) via the azomethine nitrogen atom and the thiolic sulfur atom/enolic oxygen atom. On the basis of X-ray powder diffraction study one of the representative boron complex was found to have orthorhombic lattice, having lattice parameters: a = 9.9700, b = 15.0000 and c = 7.0000. Both the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. Plant growth regulating activity of one of the ligand and its complexes has also been recorded on gram plant, and results have been discussed.

Yadav, Sunita; Singh, R. V.

2011-01-01

368

Boron and Arsenic Studies in Florida Waters.  

National Technical Information Service (NTIS)

Levels of arsenic and boron in Florida natural waters have been measured and found generally to be low and not of toxic concern. Boron levels in municipal sewage effluent are high enough to cause phytotoxicity, at least to sensitive plants such as citrus....

N. E. Carriker W. T. Gillespie P. L. Brezonik

1976-01-01

369

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-Hodgkins 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.

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

370

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

371

Pressureless sintering of boron carbide phase  

Microsoft Academic Search

While industrial hot pressing of boron carbide is well known, pressureless sintering is new. Two commercial boron carbide powders are used; the first one was synthetized by an arc-melting technique (B powder) and the second one by a magnesiothermal reaction (A powder). This last one is used after a washing with hydrochloric acid (AH powder) or after a purification by

F. Thevenot; M. Bougoin

1986-01-01

372

GREENHOUSE EVALUATION OF FOUR BORON FERTILIZER MATERIALS  

Microsoft Academic Search

Management of boron (B) in soils can be difficult since a narrow range exists between plant deficiency and toxicity. A greenhouse study was conducted to evaluate the effectiveness of four soil-applied B fertilizers varying in solubility (Granubor, Hydroboracite, Ulexite, and Colemanite) in supplying B to alfalfa (Medicago sativa L.). Boron was incorporated at rates of 0, 1, or 2 mg

D. E. Byers; R. L. Mikkelsen; F. R. Cox

2001-01-01

373

Boron nitride ceramics: Problems and development perspectives  

Microsoft Academic Search

The heat resistance, high thermal shock resistance, chemical inertness, structure, and lubricating ability of boron nitride ceramics are discussed along with its uses in high temperature and abrasive applications. Problems are reviewed in sintering, hardening, and impurity control procedures. The most effective strengthening agents for boron nitride ceramics were determined to be organosilicon compounds. A method using molecular thermal cross-linking

L. N. Rusanova; A. G. Romashin; G. I. Kulikova; O. P. Golubeva

1988-01-01

374

Method of Extracting Boron from Natural Brines.  

National Technical Information Service (NTIS)

The object of the invention is a method of extracting boron from natural brines. For a more thorough extraction of boron, the brine is treated with a mixture of lime with aluminum sulfates, or with salt of trivalent iron (for example, chloride, or sulfate...

K. I. Khrennikov

1965-01-01

375

Surface Treatment with Boron for Corrosion Protection  

Microsoft Academic Search

This paper presents the effect of boronizing on metallic materials. The coatings were produced by thermo-chemical treatment with powder mixtures at high temperature. The microstructure of obtained coatings was investigated, the microhardness was measured, and corrosion resistance was tested. Microhardness of the obtained boron coatings was measured. Corrosion tests were performed by using electro-chemical method. The corrosion rates from Tafel

Naruemon Suwattananont; Roumiana S. Petrova; James L. Zunino; Daniel P. Schmidt

376

Wear resistance of boron nitride coated metal  

Microsoft Academic Search

The wear resistance of boron nitride films was studied. The films of 1 mum thickness were prepared on the surface of a cutting tool by simultaneous nitrogen ion irradiation and vapor depositon of boron; the Vickers hardness of the films was between 3000 and 5000 kg\\/mm2. The test was performed by the cutting of steel. On the tool deposited directly,

Yasunori Andoh; Satoshi Nishiyama; Shigeki Sakai; Kiyoshi Ogata; Fuminori Fujimoto

1993-01-01

377

Real-time monitoring during transportation of a radioisotope thermoelectric generator (RTG) using the radioisotope thermoelectric generator transportation system (RTGTS)  

SciTech Connect

The Radioisotopic Thermoelectric Generators (RTGs) that will be used to support the Cassini mission will be transported in the Radioisotope Thermoelectric Generator Transportation System (RTGTS). To ensure that the RTGs will not be affected during transportation, all parameters that could adversely affect RTG's performance must be monitored. The Instrumentation and Data Acquisition System (IDAS) for the RTGTS displays, monitors, and records all critical packaging and trailer system parameters. The IDAS also monitors the package temperature control system, RTG package shock and vibration data, and diesel fuel levels for the diesel fuel tanks. The IDAS alarms if any of these parameters reach an out-of-limit condition. This paper discusses the real-time monitoring during transportation of the Cassini RTGs using the RTGTS IDAS.

Pugh, Barry K. [EG and G Mound Applied Technologies P.O. Box 3000 Miamisburg, Ohio 45343-3000 (United States)

1997-01-10

378

Real-time monitoring during transportation of a radioisotope thermoelectric generator (RTG) using the radioisotope thermoelectric generator transportation system (RTGTS)  

SciTech Connect

The Radioisotopic Thermoelectric Generators (RTGs) that will be used to support the Cassini mission will be transported in the Radioisotope Thermoelectric Generator Transportation System (RTGTS). To ensure that the RTGs will not be affected during transportation, all parameters that could adversely affect RTG{close_quote}s performance must be monitored. The Instrumentation and Data Acquisition System (IDAS) for the RTGTS displays, monitors, and records all critical packaging and trailer system parameters. The IDAS also monitors the package temperature control system, RTG package shock and vibration data, and diesel fuel levels for the diesel fuel tanks. The IDAS alarms if any of these parameters reach an out-of-limit condition. This paper discusses the real-time monitoring during transportation of the Cassini RTGs using the RTGTS IDAS. {copyright} {ital 1997 American Institute of Physics.}

Pugh, B.K. [EGG Mound Applied Technologies P.O. Box 3000 Miamisburg, Ohio45343-3000 (United States)

1997-01-01

379

Kinetics of formation of a platelet-reinforced ceramic composite prepared by the directed reaction of zirconium with boron carbide  

SciTech Connect

In this paper the kinetics of formation of a new class of ceramic composite material, zirconium diboride platelet-reinforced zirconium carbides, are discussed. These materials are prepared by the directed reaction of molten zirconium with boron carbide to form a ceramic material composed of zirconium diboride platelets approximately uniformly distributed in a zirconium carbide matrix containing a controlled amount of residual zirconium metal. Results from interrupted growth studies, differential thermal analysis, adiabatic reaction temperature calculations, and kinetic measurements have been used to study the kinetics of the process. The reaction is very fast and proceeds parabolically with time with a rate constant between 1.6 {times} 10{sup {minus}2} and 3.9 {times} 10{sup {minus}2} cm{sup 2}/s. The proposed mechanism suggests that when molten zirconium contacts boron carbide, the molten zirconium exothermically reacts with the boron carbide to form a boron-rick liquid. Further reaction is sustained by the continuous dissolution of the boron carbide as the boron-rich liquid is drawn into the boron carbide. The product is a zirconium diboride/zirconium carbide/zirconium composite which homogenizes quickly at the reaction temperature to yield a uniform product microstructure throughout the composite. Two alternative rate-limiting steps are discussed and the implications of each are explored.

Johnson, W.B.; Nagelberg, A.S.; Breval, E. (Lanxide Corp., Newark, DE (US))

1991-09-01

380

Boronated mesophase pitch coke for lithium insertion  

NASA Astrophysics Data System (ADS)

Boronated carbons from mesophase pitch have been used as materials for lithium storage in Li/carbon cells. Doping by boron has been realized by co-pyrolysis of coal tar pitch with the pyridine-borane complex. Amount of boron in mesocarbon microbeads (MCMB) varied from 1.4 to 1.8 wt.% affecting the texture of carbon. Optical microscopy and X-ray diffractograms have shown tendency to more disordered structure for boron-doped carbon. The values of specific reversible capacity ( x) varied from 0.7 to 1.1 depending significantly on the final temperature of pyrolysis (700-1150C). The optimal charge/discharge performance was observed for boronated carbon heated at 1000C.

Frackowiak, E.; Machnikowski, J.; Kaczmarska, H.; Bguin, F.

381

The Abundance of Boron in Diffuse Interstellar Clouds  

NASA Astrophysics Data System (ADS)

We present a comprehensive survey of boron abundances in diffuse interstellar clouds from observations made with the Space Telescope Imaging Spectrograph (STIS) of the Hubble Space Telescope. Our sample of 56 Galactic sight lines is the result of a complete search of archival STIS data for the B II ?1362 resonance line, with each detection confirmed by the presence of absorption from O I ?1355, Cu II ?1358, and Ga II ?1414 (when available) at the same velocity. Five previous measurements of interstellar B II from Goddard High Resolution Spectrograph observations are incorporated in our analysis, yielding a combined sample that more than quadruples the number of sight lines with significant boron detections. Our survey also constitutes the first extensive analysis of interstellar gallium from STIS spectra and expands on previously published results for oxygen and copper. The observations probe both high- and low-density diffuse environments, allowing the density-dependent effects of interstellar depletion to be clearly identified in the gas-phase abundance data for each element. In the case of boron, the increase in relative depletion with line-of-sight density amounts to an abundance difference of 0.8 dex between the warm and cold phases of the diffuse interstellar medium. The abundance of boron in warm, low-density gas is found to be B/H = (2.4 0.6) 10-10, which represents a depletion of 60% relative to the meteoritic boron abundance. Beyond the effects of depletion, our survey reveals sight lines with enhanced boron abundances that potentially trace the recent production of 11B, resulting from spallation reactions involving either cosmic rays or neutrinos. Future observations will help to disentangle the relative contributions from the two spallation channels for 11B synthesis. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Ritchey, A. M.; Federman, S. R.; Sheffer, Y.; Lambert, D. L.

2011-02-01

382

The boron heterofullerenes C 59B and C 69B: generation, extraction, mass spectrometric and XPS characterization  

NASA Astrophysics Data System (ADS)

Boron heterofullerenes can be generated by arc evaporation of doped graphite rods in a modified fullerene reactor. According to mass spectrometric analysis only mono-substituted fullerenes like C 59B, C 69B and higher homologues can be extracted and enriched by the use of pyridine as the solvent. They are strong Lewis acids and undergo a decomposition reaction to boric acid with traces of oxygen. XPS analysis of the extracts reveals the boron in the fullerene cage to be in a higher oxidation state compared to ordinary boron-carbon compounds. The synthesis and extraction procedure opens a viable route for the macroscopic production of these compounds.

Muhr, H.-J.; Nesper, R.; Schnyder, B.; Ktz, R.

1996-02-01

383

Chemical Behaviors of Energetic Deuterium Implanted into Boron Coatings  

Microsoft Academic Search

To study chemical behaviors of energetic deuterium implanted into boron coating deposited by boronization in fusion devices, two types of boron coating film deposited on silicon and IG-430U were prepared by Plasma Chemical Vapor Deposition (PCVD) technique. Boron polycrystal was used as the reference sample. The chemical behavior of deuterium was investigated by XPS (X-ray photoelectron spectroscopy) and TDS (Thermal

H. Kodama; Y. Morimoto; M. Sasaki; M. Oyaidu; Y. Oya; A. Sagara; N. Noda; K. Okuno

2003-01-01

384

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

SciTech Connect

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

Coderre, J.A.; Glass, J.D.; Micca, P.; Greenberg, D. (Brookhaven National Lab., Upton, NY (United States)); Packer, S. (Brookhaven National Lab., Upton, NY (United States) North Shore University Hospital Manhasset, NY (United States))

1990-01-01

385

Calculated Energy Deposits from the Decay of Tritium and Other Radioisotopes Incorporated into Bacteria  

PubMed Central

Transmutation of the radioisotope tritium occurs with the production of a low energy electron, having a range in biological material similar to the dimensions of a bacterium. A computer program was written to determine the radiation dose distributions which may be expected within a bacterium as a result of tritium decay, when the isotope has been incorporated into specific regions of the bacterium. A nonspherical model bacterium was used, represented by a cylinder with hemispherical ends. The energy distributions resulting from a wide variety of simulated labeled regions were determined; the results suggested that the nuclear region of a bacterium receives on the average significantly different per decay doses, if the labeled regions were those conceivably produced by the incorporation of thymidine-3H, uracil-3H, or 3H-amino acids. Energy distributions in the model bacterium were also calculated for the decay of incorporated 14carbon, 35sulfur, and 32phosphorous.

Bockrath, Richard; Person, Stanley; Funk, Fred

1968-01-01

386

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

387

Boron-10 Lined Proportional Counter Model Validation  

SciTech Connect

The decreasing supply of 3He is stimulating a search for alternative neutron detectors; one potential 3He replacement is 10B-lined proportional counters. Simulations are being performed to predict the performance of systems designed with 10B-lined tubes. Boron-10-lined tubes are challenging to model accurately because the neutron capture material is not the same as the signal generating material. Thus, to simulate the efficiency, the neutron capture reaction products that escape the lining and enter the signal generating fill gas must be tracked. The tube lining thickness and composition are typically proprietary vendor information, and therefore add additional variables to the system simulation. The modeling methodologies used to predict the neutron detection efficiency of 10B-lined proportional counters were validated by comparing simulated to measured results. The measurements were made with a 252Cf source positioned at several distances from a moderated 2.54-cm diameter 10B-lined tube. Models were constructed of the experimental configurations using the Monte Carlo transport code MCNPX, which is capable of tracking the reaction products from the (n,10B) reaction. Several different lining thicknesses and compositions were simulated for comparison with the measured data. This paper presents the results of the evaluation of the experimental and simulated data, and a summary of how the different linings affect the performance of a coincidence counter configuration designed with 10B-lined proportional counters.

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

2012-11-18

388

Boron Nitride Nanoribbons Becomes Metallic  

SciTech Connect

Standard spin-polarized density functional theory calculations have been conducted to study the electronic structures and magnetic properties of O and S functionalized zigzag boron nitride nanoribbons (zBNNRs). Unlike the semiconducting and nonmagnetic H edge-terminated zBNNRs, the O edge-terminated zBNNRs have two energetically degenerate magnetic ground states with a ferrimagnetic character on the B edge, both of which are metallic. In contrast, the S edge-terminated zBNNRs are nonmagnetic albeit still metallic. An intriguing coexistence of two different Peierls-like distortions is observed for S edge-termination that manifests as a strong S dimerization at the B zigzag edge and a weak S trimerization at the N zigzag edge, dictated by the band fillings at the vicinity of the Fermi level. Nevertheless, metallicity is retained along the S wire on theNedge due to the partial filling of the band derived from the pz orbital of S. A second type of functionalization with O or S atoms embedded in the center of zBNNRs yields semiconducting features. Detailed examination of both types of functionalized zBNNRs reveals that the p orbitals on O or S play a crucial role in mediating the electronic structures of the ribbons.We suggest that O and S functionalization of zBNNRs may open new routes toward practical electronic devices based on boron nitride materials.

Huang, Jingsong [ORNL; Terrones Maldonado, Humberto [ORNL; Sumpter, Bobby G [ORNL; Lopez-Benzanilla, Alejandro [Oak Ridge National Laboratory (ORNL)

2011-01-01

389

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

390

Boron-Loaded Silicone Rubber Scintillators  

SciTech Connect

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

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

2003-05-12

391

Boron isotope geochemistry as a tracer for the evolution of brines and associated hot springs from the Dead Sea, Israel  

Microsoft Academic Search

A boron isotope study combined with analyses of elemental boron, lithium, and chlorine is used to suggest that brines from the Dead Sea and on-shore hypersaline thermal springs (Hamme Yesha, Hamme Zohar, and Hamme Mazor) are the products of interaction of evaporated seawater with detrital sediments. The high 11 B values of the Dead Sea brines (55.7 to 57.4%. versus

Avner Vengosh; Abraham Starinsky; Yehoshua Kolodny; Allan R. Chivas

1991-01-01

392

Conversion electron and X-ray Mssbauer studies of boronized low-carbon steel under corrosion and oxidation conditions  

Microsoft Academic Search

Iron-boride layers on low-carbon steel were produced by thermochemical diffusion process. The surface interaction products: Fe2B, FeB, FeBx (x>1) and a solid solution of iron in boron were identified by surface Mssbauer spectroscopy (CEMS and XMS). Samples of original and boronized steel were subjected to corrosion process by immersion in HCl (0.1 N) solution for 150 h. While the steel

A. Abras; A. A. G. Campos; A. V. de Carvalho; L. O. Ladeira

1986-01-01

393

Application of 11B MAS-NMR to the characterization of boron in coal fly ash generated from Nantun coal  

Microsoft Academic Search

Boron and its compounds are environmentally hazardous substance and are well-known condensed products that appear in coal fly ash during combustion of coal in coal-fired electric power stations. In a previous study, we suggested that boron in coal fly ash obtained from Nantun coal in China, identified as AshN, may exist on the surface of relatively large coal fly ash

Shunsuke Kashiwakura; Takafumi Takahashi; Hideki Maekawa; Tetsuya Nagasaka

2010-01-01

394

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.

Liu, Hongsheng; Gao, Junfeng; Zhao, Jijun

2013-01-01

395

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

396

Radioisotope Stirling Generator Options for Pluto Fast Flyby Mission  

NASA Astrophysics Data System (ADS)

The preceding paper (Schock 1994) described conceptual designs and analytical results for five Radioisotope Thermoelectric Generator (RTG) options for the Pluto Fast Flyby (PFF) mission, and the present paper describes three Radioisotope Stirling Generator (RSG) options for the same mission. The RSG options are based on essentially the same radioisotope heat source modules used in previously flown RTGs and on designs and analyses of a 75-Watt free-piston Stirling engine produced by Mechanical Technology Incorporated (MTI) for NASA's Lewis Research Center. The integrated system design options presented were generated in a Fairchild Space study sponsored by the Department of Energy's Office of Special Applications, in support of ongoing PFF mission and spacecraft studies that the Jet Propulsion Laboratory (JPL) is conducting for the National Aeronautics and Space Administration (NASA). That study's NASA-directed goal is to reduce the spacecraft mass from its baseline value of 166 kg to -110 kg, which implies a mass goal of less than 10 kg for a power source able to deliver 69 Watts(e) at the end of the 9.2-year mission. In general, the Stirling options were found to be lighter than the thermoelectric options described in the preceding paper. But they are less mature, requiring more development, and entailing greater programmatic risk. The Stirling power system mass ranged from 7.3 kg (well below the 10-kg goal) for a non-redundant system to 11.3 kg for a redundant system able to maintain full power if one of its two engines fails. In fact, the latter system could deliver as much as 115 Watts(e) if desired by the mission planners.

Schock, Alfred

1994-07-01

397

Development of Advanced Stirling Radioisotope Generator for Space Exploration  

NASA Technical Reports Server (NTRS)

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 to 7 We/kg, along with a 25 percent 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

398

A radioisotope powered cryobot for penetrating the Europan ice shell  

NASA Astrophysics Data System (ADS)

The Cryobot team at JPL has been working on the design of a Cryo-Hydro Integrated Robotic Penetrator System (CHIRPS), which can be used to penetrate the Mars North Polar Cap or the thick sheet ice surrounding Jupiter's moon, Europa. The science for either one of these missions is compelling. For both Mars and Europa the major scientific interest is to reach regions where there is a reservoir of water that may yield signs of past or extant life. Additionally, a Mars polar cap penetration would help us understand both climatic and depositional histories for perhaps as far back as 20 million years. Similarly, penetration of the Europa ice sheet would allow scientists to unravel the mysteries surrounding the thick ice crust, its chemical composition, and subsurface ocean properties. Extreme mass and power constraints make deep drilling/coring impractical. The best way to explore either one of these environments is a cryobot mole penetrator vehicle, which carries a suite of instruments suitable for sampling and analyzing the ice or ocean environments. This paper concentrates on a Europa deep ice (i.e., kilometers thick) application of the CHIRPS, and introduces the reader to the vehicle design with focus on the use of radioisotope thermoelectric generator (RTG) technology as the primary heat (1 kW total) and power source for the robotic vehicle. Radioisotope heater unit (RHU) milli-watt power systems (120 mW total) are also employed to power the mini-radiowave ice transceivers, which are used to relay data through the ice up to the surface lander. The results of modeling and design work for both of these areas are discussed in this paper. Although radioisotope power is baselined for the Europa flight version of the cyrobot, no decision on the final design of the cryobot will be made until the environmental review process is complete. Any use of the cryobot for Mars or Europa will conform to all environmental and planetary protection requirements. .

Zimmerman, Wayne; Bryant, Scott; Zitzelberger, John; Nesmith, Bill

2001-02-01

399

Radioisotope Stirling Generator Options for Pluto Fast Flyby Mission  

SciTech Connect

The preceding paper described conceptual designs and analytical results for five Radioisotope Thermoelectric Generator (RTG) options for the Pluto Fast Flyby (PFF) mission, and the present paper describes three Radioisotope Stirling Generator (RSG) options for the same mission. The RSG options are based on essentially the same radioisotope heat source modules used in previously flown RTGs and on designs and analyses of a 75-watt free-piston Stirling engine produced by Mechanical Technology Incorporated (MTI) for NASA's Lewis Research Center. The integrated system design options presented were generated in a Fairchild Space study sponsored by the Department of Energy's Office of Special Applications, in support of ongoing PFF mission and spacecraft studies that the Jet Propulsion Laboratory (JPL) is conducting for the National Aeronautics and Space Administration (NASA). That study's NASA-directed goal is to reduce the spacecraft mass from its baseline value of 166 kg to ~110 kg, which implies a mass goal of less than 10 kg for a power source able to deliver 69 watts(e) at the end of the 9.2-year mission. In general, the Stirling options were found to be lighter than the thermoelectric options described in the preceding paper. But they are less mature, requiring more development, and entailing greater programmatic risk. The Stirling power system mass ranged from 7.3 kg (well below the 10-kg goal) for a non-redundant system to 11.3 kg for a redundant system able to maintain full power if one of its engines fails. In fact, the latter system could deliver as much as 115 watts(e) if desired by the mission planners. There are 5 copies in the file.

Schock, Alfred

1993-10-01

400

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 19002000 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

401

A new family of chiral boron fullerenes and related planar boron sheet  

Microsoft Academic Search

Using the recent idea of balancing two-center and three-center bondings between boron atoms, a new class of stable chiral boron nanostructures (fullerenes and nanotubes) is designed. The structures of these fullerenes consist of triangular and hexagonal motifs similar to those seen in the most stable alpha-boron sheet and the B80 fullerene. The binding energy of the new sheet is only

Rajendra Zope; Tunna Baruah

2010-01-01

402

Synthesis and characterization of terpyridine-supported boron cations: evidence for pentacoordination at boron.  

PubMed

Hypervalent boron centers are proposed to be key intermediates in many stoichiometric and catalytic reactions. However, structurally characterized examples remain rare. We have isolated two new borocations with formal charges of 1+ and 2+. Because the dicationic complex displays evidence of pentacoordination at the boron center, we conclude that the interaction is predominantly electrostatic and is a result of the highly electrophilic dicationic boron atom. PMID:24256124

McGovern, Gregory P; Zhu, Di; Aquino, Adelia J A; Vidovi?, Dragoslav; Findlater, Michael

2013-12-16

403

Separation of Boron from Geothermal Water Using a Boron Selective Macroporous Weak Base Anion Exchange Resin  

Microsoft Academic Search

In this study, batch and column mode tests were performed to evaluate the efficiency of boron removal from geothermal water containing 10-11mgB\\/L using Lewatit MK 51 which is a macroporous weak base anion exchange resin with polyhydroxyl groups showing a very high selectivity and capacity for boron. The optimum resin amount for boron removal from geothermal water was determined as

Idil Yilmaz-Ipek; Pelin Koseoglu; Umran Yuksel; Nazl? Yasar; Gzde Yolseven; Mithat Yuksel; Nalan Kabay

2010-01-01

404

Boron adsorption using a new boron-selective hybrid gel and the commercial resin D564  

Microsoft Academic Search

A new hybrid gel with boron-selective functional groups is prepared with tetraethoxysilane (TEOS), (3-glycidoxypropyl)trimethoxysilane (GPTMS), and a new precursor (W) synthesized from GPTMS and N-methylglucamine (MG). We investigate the boron adsorption onto the hybrid gel and the commercial resin D564 in aqueous solution by varying the initial boron concentration, pH, ionic strength, and temperature. Adsorption of both the hybrid gel

Haining Liu; Xiushen Ye; Quan Li; Taehoon Kim; Binju Qing; Min Guo; Fei Ge; Zhijian Wu; Kangtaek Lee

2009-01-01

405

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

406

Elastic moduli of a boron nitride nanotube  

NASA Astrophysics Data System (ADS)

The elastic properties of boron nitride nanotubes have been calculated using the Tersoff-Brenner potential which is a bond order potential used successfully previously for carbon nanotubes. In the present calculation, the same form of potential is used with adjusted parameters for hexagonal boron nitride. The Young's modulus and shear modulus for single-walled armchair and zigzag tubes of different radii have been calculated. The effects of tube diameter are investigated. The computational results show the variation of Young's modulus and shear modulus of boron nitride nanotubes with nanotube diameter. The results have been compared with available data, experimental as well as calculated.

Verma, Veena; Jindal, V. K.; Dharamvir, Keya

2007-10-01

407

Electronic structure of polycrystalline Cd metal using 241Am radioisotope  

NASA Astrophysics Data System (ADS)

Electronic structure study of the polycrystalline cadmium metal is reported. The experimental measurement is undertaken on a polycrystalline sheet sample using 59.54 keV radioisotope of 241Am. These results are compared with the ab initio calculations. The theoretical calculations are performed using linear combination of atomic orbitals (LCAO) method employing the density functional theories (DFT) and Hartree-Fock (HF) and augmented plane wave (APW) methods. The spherically averaged APW and LCAO based theoretical Compton profiles are in good agreement with the experimental measurement however the APW based theoretical calculations show best agreement.

Dhaka, M. S.; Sharma, G.; Mishra, M. C.; Sharma, B. K.

2014-04-01

408

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

409

Pharmacokinetic study of polymeric drugs. Radioisotopic method for pharmacokinetic investigations  

SciTech Connect

The authors examine the radioisotopic procedure possibilities using as example a study of the pharmacokinetics of delta-chymotrypsin (I) labeled with /sup 125/I, (/sup 125/I-I). Labeled /sup 125/I-(I) was obtained by the electrochemical iodination of (I) at constant potential when no appreciable change in the enzymic activity of the preparation occurred. Rats were used in the experiments, and the results are shown of determining radioactivity in their blood and organs. The results of the pharmacokinetic investigation of (I) show the expediency of using the proposed pharmacokinetic model in an operative pharmacokinetic check of polymeric drugs.

Pimenova, G.N.; Matveev, V.A.; Kulakov, V.N.

1987-02-01

410

Analytical predictions of RTG power degradation. [Radioisotope Thermoelectric Generator  

NASA Technical Reports Server (NTRS)

The DEGRA computer code that is based on a mathematical model which predicts performance and time-temperature dependent degradation of a radioisotope thermoelectric generator is discussed. The computer code has been used to predict performance and generator degradation for the selenide Ground Demonstration Unit (GDS-1) and the generator used in the Galileo Project. Results of parametric studies of load voltage vs generator output are examined as well as the I-V curve and the resulting predicted power vs voltage. The paper also discusses the increased capability features contained in DEGRA2 and future plans for expanding the computer code performance.

Noon, E. L.; Raag, V.

1979-01-01

411

Radioisotope measurement of the velocity of tracheal mucus  

SciTech Connect

A radioisotope scanning technique for measuring the velocity of tracheal mucus has been developed utilizing a canine model. A solution of stannous phytate labeled with /sup 99m/Tc is introduced percutaneously into the lower trachea and the upward movement of the leading edge of the radioactivity is followed by repeat scanning at 2-minute intervals using a modified rectilinear scanner, thus allowing calculation of the velocity of the mucus. It is believed that this technique may be of value in studying the effect of experimentally induced tracheal injuries on mucus velocity. Possible applications of the technique for the study of the velocity of mucus in the human trachea are discussed.

Russo, K.J.; Palmer, D.W.; Beste, D.J.; Carl, G.A.; Belson, T.P.; Pelc, L.R.; Toohill, R.J.

1985-04-01

412

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 260mM 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 2.7-3.7mgl(-1) boron from the medium and fly ash at 168h. 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

413

Synthesis of boron nitride powders  

NASA Astrophysics Data System (ADS)

In the materials science community there is much interest in the development of new, efficient approaches for preparing ceramic powders having properties or performance characteristics not found with powders produced by traditional metallurgical synthesis methods. In this regard, aerosol-based syntheses are finding general acceptance for the preparation of non-metal and metal oxide powders. In contrast, much less effort has been given to aerosol-type syntheses for non-oxide powders despite potentially useful benefits. This dissertation describes the application of two chemical systems in aerosol assisted vapor phase synthesis (AAVS) for the preparation of spherical morphology boron oxynitride, BNxOy, powders that are subsequently converted to spherical morphology boron nitride in a second nitridation step. Chapter 1 describes the AAVS synthesis of BNxOy powders using a reaction of an aqueous boric acid containing aerosol with ammonia at 1000C. The effect of reactor tube material, total gas flow rate, ammonia concentration, boric acid concentration, and urea addition to the boric acid aerosol on the percent oxygen composition is described. The resulting BNxOy powders contain significant amounts of oxygen that require replacement in a second stage nitridation reaction at elevated temperature under ammonia. The influences of the reaction temperature profile, crucible geometry and transformation additive on final oxygen composition and powder crystallinity are described. Chapter 2 outlines the formation of BNxOy powders from an AAVS reaction between the boron precursor (MeO)3B and ammonia. The formation of the powders is studied as a function of total gas flow rate and ammonia concentration. In all cases the resulting powders contain lower levels of oxygen compared to powders produced from aqueous boric acid aerosols. The conversion of the BNxOy powders in the second stage nitridation reaction with ammonia is examined as a function of crucible geometry, temperature profile and ammonia flow rate. In support of this process, the molecular reaction between (MeO)3B and NH3 was reexamined. The adduct, (MeO)3BNH3, was isolated and its molecular structure determined by single crystal X-ray diffraction techniques. The results of these studies provide guidance for more detailed studies that should result in industrial scale synthesis of spherical morphology BN which currently is not formed by standard metallurgical syntheses. This new material has potential applications in several areas including the formation of BN loaded organic polymer composites.

Dreissig, Dirk Horst

2002-09-01

414

Borocaptate sodium: a potential boron delivery compound for boron neutron capture therapy evaluated in dogs with spontaneous intracranial tumors.  

PubMed

Borocaptate sodium (Na2B12H11SH) is a boron-carrying compound under consideration for use in boron neutron capture therapy. The biodistribution of boron from borocaptate sodium administration will partly determine boron neutron capture therapy efficacy and normal tissue radiation tolerance. The biodistribution of boron was determined in 30 dogs with spontaneous intracranial tumors at 2, 6, or 12 hr after intravenous borocaptate sodium infusion. Blood and tissue boron concentrations were measured using inductively coupled plasma atomic emission spectroscopy. Mean tumor boron concentration (mean +/- standard error) was 35.9 +/- 4.6 (n = 15), 22.5 +/- 6.0 (n = 9), and 7.0 +/- 1.1 micrograms of boron per g (n = 6) at 2, 6, and 12 hr, respectively, after borocaptate sodium infusion. Peritumor boron concentrations were elevated above that of normal brain in half of the dogs. Normal brain boron concentration (mean +/- standard error) was 4.0 +/- 0.5, 2.0 +/- 0.4, and 2.0 +/- 0.3 micrograms of boron per g at 2, 6, and 12 hr after infusion, respectively. Some cranial and systemic tissues, and blood, had high boron concentration relative to tumor tissue. Geometric dose sparing should partly offset these relatively high normal tissue and blood concentrations. Borocaptate sodium biodistribution is favorable because tumor boron concentrations of recommended magnitude for boron neutron capture therapy were obtained and there was a high tumor-to-normal brain boron concentration ratio. PMID:1465427

Kraft, S L; Gavin, P R; DeHaan, C E; Leathers, C W; Bauer, W F; Miller, D L; Dorn, R V

1992-12-15

415

Removal of Vanadium from Molten AluminumPart III. Analysis of Industrial Boron Treatment Practice  

NASA Astrophysics Data System (ADS)

Transition metal impurities (V, Ti, Zr, and Cr) reduce the electrical conductivity of smelter grade aluminum. These impurities are removed in the form of their borides by reacting with added Al-B master alloys i.e., boron treatment. Although, boron treatment is widely used for the production of high purity aluminum alloys in casthouse the fundamental understanding is lacking and published industrial data are limited. In the current study, industrial trials on the removal of impurities were conducted at one of the high purity aluminum alloys producers in Australasia. Kinetics analysis revealed that the rate of reaction is controlled by the mass transfer of impurities in the bulk melt. The measured mass transfer coefficient ( k m) of V and Ti were 1.1 10-4 and 2.6 10-4 m/s respectively, in the naturally stirred molten aluminum. The rate of V and Ti removal was faster compared to Zr and Cr during the boron treatment of smelter grade aluminum. Mass balance analysis revealed that 70 wt pct of V and Ti combined as borides in the first hour of the total 12 hours of boron treatment process. The calculated amount of un-reacted B was approximately 25.5 wt pct of initial amount added that remained in the final alloy. There was no evidence of boride rings formation, although partially dissolved AlB12 particles were observed under scanning electron microscope. Finally, implications for industrial practice are discussed for the improvement of current boron treatment process that include changing the source of boron, multiple stage addition of boron and better stirring of the molten aluminum.

Khaliq, Abdul; Akbar Rhamdhani, Muhammad; Brooks, Geoffrey A.; Grandfield, John

2014-04-01

416

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

417

Boron-10 loaded inorganic shielding material  

NASA Technical Reports Server (NTRS)

Shielding material containing Boron 10 and gadoliunium for neutron absorption has been developed to reduce interference from low energy neutrons in measurement of fission neutron spectrum using Li-6 fast neutron spectrometer.

Baker, S. I.; Ryskiewicz, R. S.

1972-01-01

418

Boron strengthening in FeAl  

SciTech Connect

The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C. [Dartmouth Coll., Hanover, NH (United States). Thayer School of Engineering; Carleton, R.L.; George, E.P. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1998-11-01

419

Safe bending of boron/aluminum sheets  

NASA Technical Reports Server (NTRS)

Low cost procedure utilizing aluminum backing sheets protects boron/aluminum sheet from cracking during bending. Process utilizes inexpensive universal-brake bending dies rather than special hydroforming dies.

Liskay, G. G.; Yoshino, S. Y.

1980-01-01

420

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

421

Nuclear reaction microanalysis of boron doped steels  

NASA Astrophysics Data System (ADS)

The microanalysis of trace amounts of boron has been carried out using a 1 ?m proton microbeam from the 3 MV single-ended electrostatic accelerator of TIARA facility, JAEA Takasaki. Steel specimens containing 20-100 ppm boron have been bombarded by 1.7 MeV proton beam for ?-ray detection and 1.32 MeV H2+ beam for ?-particles. The maps of boron distribution have been measured by detecting 428 keV ?-rays emitted from the 10B (p, ?'?) 7Be nuclear reaction and 3.7 MeV ?-particles from the 11B (p, ?) 8Be nuclear reaction. As a result of imaging, segregation of several micron sized boron precipitates could be clearly seen.

Shibata, H.; Kohno, Y.; Shibata, K.; Sato, T.; Oikawa, M.; Haga, J.; Sakai, T.

2007-07-01

422

Synthesis of boron-containing primary amines.  

PubMed

In this study, boron-containing primary amines were synthesized for use as building blocks in the study of peptoids. In the first step, Gabriel synthesis conditions were modified to enable the construction of seven different aminomethylphenyl boronate esters in good to excellent yields. These compounds were further utilized to build peptoid analogs via an Ugi four-component reaction (Ugi-4CR) under microwave irradiation. The prepared Ugi-4CR boronate esters were then successfully converted to the corresponding boronic acids. Finally, the peptoid structures were successfully modified by cross-coupling to aryl/heteroaryl chlorides via a palladium-mediated Suzuki coupling reaction to yield the corresponding derivatives in moderate to good yields. PMID:24108399

Chung, Sheng-Hsuan; Lin, Ting-Ju; Hu, Qian-Yu; Tsai, Chia-Hua; Pan, Po-Shen

2013-01-01

423

Analysis, optimization, and assessment of radioisotope thermophotovoltaic system design for an illustrative space mission  

Microsoft Academic Search

A companion paper presented at this conference described the design of a Radioisotope Thermophotovoltaic (RTPV) Generator for an illustrative space mission (Pluto Fast Flyby). It presented a detailed design of an integrated system consisting of a radioisotope heat source, a thermophotovoltaic converter, and an optimized heat rejection system. The present paper describes the thermal, electrical, and structural analyses which led

A. Schock; M. Mukunda; G. Summers

1995-01-01

424

Radioisotope thermophotovoltaic system design and its application to an illustrative space mission  

Microsoft Academic Search

The paper describes the results of a DOE-sponsored design study of a radioisotope thermophotovoltaic generator (RTPV), to complement similar studies of Radioisotope Thermoelectric Generators (RTGs) and Stirling Generators (RSGs) previously published by the author. Instead of conducting a generic study, it was decided to focus the design effort by directing it at a specific illustrative space mission, Pluto Fast Flyby

A. Schock; V. Kumar

1995-01-01

425

Analysis, Optimization, and Assessment of Radioisotope Thermophotovoltaic System Design for an Illustrative Space Mission  

Microsoft Academic Search

A companion paper presented at this conference described the design of a Radioisotope Thermophotovoltaic (RTPV) Generator for an illustrative space mission (Pluto Fast Flyby). It presented a detailed design of an integrated system consisting of a radioisotope heat source, a thermophotovoltaic converter, and an optimized heat rejection system. The present paper describes the thermal, electrical, and structural analyses which led

Alfred Schock; Meera Mukunda; G. Summers

1994-01-01

426

[Radioisotope therapy with somatostatin analogues in neuroendocrine tumours (case report)].  

PubMed

Restricted number of neuroendocrine tumors (NET) shows overexpression of somatostatin receptors. Therefore, long-acting somatostatin analogues are used in diagnosis and treatment of those tumors. Here we present our first case of NET, localized in pancreas treated with DOTA-D-Phe 1-Tyr 3-octreotide (DOTATATE), for receptor-mediated radioisotope therapy. DOTATATE is a newly developed somatostatin analogue labeled with beta-emitter yttrium 90 (90Y) and beta, gamma-emitter lutetium 177 (177Lu). A 34-year old woman was suffering from several years gastrointestinal symptoms. NET of the pancreas with multiple metastases into the liver was diagnosed based on histopatological, biochemical and radiological tests. First, she had chemiotherapy (leucovorin, 5-FU, cisplatin), however there was any positive effects of this therapy. Next, she received four single doses of 90Y DOTATATE at 4-6- week intervals, yielding a cumulative dose of 7.4 GBq/m2. During the 4th cycle the Lu-177 DOTATATE was additionally administered. As a renal protection i.v. infusion of amino acid solution were used during the treatment sessions. To date, patient has shown partial remission with reduction of tumor masses. We observed spectacular clinical, biochemical and radiological improvement. Radioisotope therapy could be a powerful and promising method of treatment at least in patients who had no other treatment option. PMID:16335674

Kunikowska, Jolanta; Krlicki, Leszek; Cwik?a, Jaros?aw; Miko?ajczak, Renata; Pawlak, Dariusz; Korsak, Agnieszka; Koz?owicz, Izabela; Poprawski, Jakub; P?azi?ska, Maria; Kobylecka, Ma?gorzata; Maczewska, Joanna; Zyci?ska, Katarzyna; Wardyn, Kazimierz

2005-01-01

427

[Radioisotope decontamination of X-ray detector (photostimulable phosphor plate)].  

PubMed

We tried to remove contamination of radioisotope (RI) for an X-ray detector (photostimulable phosphor plate; IP) and verified that our procedure suggested by Nishihara et al. was effective for decontamination. The procedure was as follows. First, the IP was kept for approximately twelve hours, and then it was processed [image (A)] as well as a clinical processing mode. Second, using a wet-type chemical wiper, we scavenged the IP to remove the adhered RI on its surface. Then, once again, the IP was kept for approximately fifteen hours and processed [image (B)] in order to check an effect of decontamination. Finally, the two images of (A) and (B) were analyzed using ImageJ, which can be downloaded as a free software, and a percentage of removal was calculated. The procedure was applied to two IPs using the FCR 5501 plus. In the present case, the percentage of removal was approximately 96%. The removed radioisotopes in the chemical wipers were analyzed by Ge detector. Then, (134)Cs and (137)Cs were found with activities of 2.9 4.3 Bq and 3.5 5.2 Bq, respectively. For three months after that, we cannot see black spots on the IPs owing to the contamination of the RI and there are no defects caused by decontamination using a wet-type chemical wiper. PMID:22449904

Onuma, Yoji; Hayashi, Michiko; Hayashi, Hiroaki; Nishihara, Sadamitsu

2012-01-01

428

GRC Supporting Technology for NASA's Advanced Stirling Radioisotope Generator (ASRG)  

NASA Technical Reports Server (NTRS)

From 1999 to 2006, the NASA Glenn Research Center (GRC) supported a NASA project to develop a high-efficiency, nominal 110-We Stirling Radioisotope Generator (SRG110) for potential use on NASA missions. Lockheed Martin was selected as the System Integration Contractor for the SRG110, under contract to the Department of Energy (DOE). The potential applications included deep space missions, and Mars rovers. The project was redirected in 2006 to make use of the Advanced Stirling Convertor (ASC) that was being developed by Sunpower, Inc. under contract to GRC, which would reduce the mass of the generator and increase the power output. This change would approximately double the specific power and result in the Advanced Stirling Radioisotope Generator (ASRG). The SRG110 supporting technology effort at GRC was replanned to support the integration of the Sunpower convertor and the ASRG. This paper describes the ASRG supporting technology effort at GRC and provides details of the contributions in some of the key areas. The GRC tasks include convertor extended-operation testing in air and in thermal vacuum environments, heater head life assessment, materials studies, permanent magnet characterization and aging tests, structural dynamics testing, electromagnetic interference and electromagnetic compatibility characterization, evaluation of organic materials, reliability studies, and analysis to support controller development.

Schreiber, Jeffrey G.; Thieme, Lanny G.

2008-01-01

429

Radioisotope Electric Propulsion for Deep Space Sample Return  

SciTech Connect

The need to answer basic questions regarding the origin of the Solar System will motivate robotic sample return missions to destinations like Pluto, its satellite Charon, and objects in the Kuiper belt. To keep the mission duration short enough to be of interest, sample return from objects farther out in the Solar System requires increasingly higher return velocities. A sample return mission involves several complicated steps to reach an object and obtain a sample, but only the interplanetary return phase of the mission is addressed in this paper. Radioisotope electric propulsion is explored in this parametric study as a means to propel small, dedicated return vehicles for transferring kilogram-size samples from deep space to Earth. Return times for both Earth orbital rendezvous and faster, direct atmospheric re-entry trajectories are calculated for objects as far away as 100 AU. Chemical retro-rocket braking at Earth is compared to radioisotope electric propulsion but the limited deceleration capability of chemical rockets forces the return trajectories to be much slower.

Noble, Robert J.; /SLAC

2009-07-14

430

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

431

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

432

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

433

Ground-state properties of boron-doped diamond  

SciTech Connect

Boron-doped diamond undergoes an insulator-metal or even a superconducting transition at some critical value of the dopant concentration. We study the equilibrium lattice parameter and bulk modulus of boron-doped diamond experimentally and in the framework of the density functional method for different levels of boron doping. We theoretically consider the possibility for the boron atoms to occupy both substitutional and interstitial positions and investigate their influence on the electronic structure of the material. The data suggest that boron softens the lattice, but softening due to substitutions of carbon with boron is much weaker than due to incorporation of boron into interstitial positions. Theoretical results obtained for substitution of carbon are in very good agreement with our experiment. We present a concentration dependence of the lattice parameter in boron-doped diamond, which can be used for to identify the levels of boron doping in future experiments.

Zarechnaya, E. Yu., E-mail: ezarechnaya@yahoo.com; Isaev, E. I. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation)], E-mail: eyvaz_isaev@yahoo.com; Simak, S. I. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden); Vekilov, Yu. Kh. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation); Dubrovinsky, L. S. [University of Bayreuth, Bayerisches Geoinstitut (Germany); Dubrovinskaia, N. A. [University of Heidelberg, Mineralogisches Institut (Germany); Abrikosov, I. A. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden)

2008-04-15

434

Boronline, a new generation of boron meter  

SciTech Connect

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

Pirat, P. [Rolls-Royce Company, Meylan (France)

2011-07-01

435

Boron nitride nanosystems of regular geometry  

Microsoft Academic Search

The explicit expressions in term of B-N bond length are obtained for atomic site coordinates and intersite distances in regular boron nitride nanotubes and fullerenes. The radii of single-walled BN nanotubes and single-shelled BN fullerenes are estimated, and their most stable associations in form of double-walled nanotubes and double-shelled fullerenes are predicted. The differences between radii of regular boron nitride

Levan Chkhartishvili

2009-01-01

436

Boron carbide coatings on diamond particles  

Microsoft Academic Search

Boron carbide (B4C) coatings on diamond offer potential for obtaining homogeneous B4C-diamond composites with improved properties. A method was developed for coating diamond particles with B4C at 1150C under argon atmosphere for dwell times of 26hours in a powder mixture of boric acid (H3BO3) and amorphous boron. The B4C coating showed very good adhesion to the diamond substrate, and an

A. H. Ras; F. D. Auret; J. M. Nel

2010-01-01

437

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

438

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

439

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

440

Method for fabricating boron carbide articles  

Microsoft Academic Search

The fabrication of boron carbide articles having length-to-diameter or width ratios greater than 2 to 1 is described. The process consists of hot pressing boron carbide powder into article segments or portions in which the segments have a length-to-diameter or width ratio less than 1.5, aligning a plurality of the initially hot-pressed segments in a hot-pressing die with the end

Ardary

1978-01-01

441

Method for fabricating boron carbide articles  

Microsoft Academic Search

The present invention is directed to the fabrication of boron carbide articles having length-to-diameter or width ratios greater than 2 to 1. The process of the present invention is practiced by the steps comprising hot pressing boron carbide powder into article segments or portions in which the segments have a length-to-diameter or width ratio less than 1.5, aligning a plurality

Zane L. Ardary; Carl D. Reynolds

1980-01-01

442

Interaction of boron carbide with vanadium oxide  

Microsoft Academic Search

The present work continues the systematic investigation of the processes of interaction of boron carbide with oxides of metals of period IV of the periodic table [I-3]. The nature of the interaction of boron carbide with vanadium oxide in obtaining the composite material B4C-VB. 2 was studied so as to establish the stages of the process, the composition of the

G. N. Makarenko; S. P. Gordienko; V. B. Fedorus; I. I. Timofeeva; E. V. Marek

1998-01-01

443

Boron isotope systematics of marine sediments  

Microsoft Academic Search

Boron contents and boron isotopic compositions were determined for modern and ancient (Permian to Miocene) marine sediments, including pelagic clay, calcareous ooze, siliceous ooze and neritic clay sediments. delta11B values of modern marine sediments range from -6.6 to +4.80\\/00. Isotopic variation is controlled by the simple mixing of four major constituents, detritus of continental origin, marine smectite, biogenic carbonates and

Tsuyoshi Ishikawa; Eizo Nakamura

1993-01-01

444

Hard and tough boron suboxide based composites  

Microsoft Academic Search

Boron suboxide (B6O) powder was synthesized at temperatures of about 1400C from the reaction of amorphous boron powder with boric acid. The synthesized B6O powders were hot pressed at temperatures up to 1900C and at pressures of 50MPa. Additionally to pure B6O materials, composites with aluminium were prepared. The microstructure and properties of the sintered compacts were investigated. The addition

T. C. Shabalala; D. S. McLachlan; I. Sigalas; M. Herrmann

2008-01-01

445

Boron nitride nanotubes: nanoparticles functionalization and junction fabrication.  

PubMed

Adopting a wet chemistry method, Au and Fe3O4 nanoparticles were functionalized on boron nitride nanotubes (BNNTs) successfully for the first time. X-ray diffraction pattern and transmission electron microscopy were used to characterize the resultant products. Subsequently, a method was proposed to fabricate heterojunction structures based on the particle-functionalized BNNTs. As a demonstration, BNNT-carbon nanostructure, BNNT-ZnO and BNNT-Ga2O3 junctions were successfully fabricated using the functionalized particles as catalysts. PMID:17450790

Zhi, Chunyi; Bando, Yoshio; Shen, Guozhen; Tang, Chengchun; Golberg, Dmitri

2007-02-01

446

Simulation and experimental study of boron clustering in crystalline silicon  

NASA Astrophysics Data System (ADS)

The tight-binding (TB) method in conjunction with atomic-scale computer simulation methods is used to study boron and boron-defect clusters containing up to five boron atoms and four self-interstitials within a matrix of crystalline silicon. As a particularly important p-type dopant, boron exhibits some problematical phenomena during the fabrication of microelectronic devices, especially transient enhanced diffusion (TED) following ion implantation of boron and subsequent annealing steps. The major focus in this thesis involves a search for particularly stable boron clusters (up to B4I 4), an investigation of possible precipitation paths of boron atoms following ion implantation and the dissolution mechanism of boron-interstitial clusters in the subsequent annealing steps. Though no clear mechanism of dissolution of boron clusters is found, key events were identified, such as diffusion of self-interstitials, stranding boron atoms, and the formation of mobile interstitial boron atoms. The extensive atomic information on the energetics and kinetics of point defects and dopant defects accumulated by these studies are used in a continuum-level process simulator---ALAMODE---to simulate boron diffusion in predeposition cases. The only inputs to ALAMODE are the atomic-scale results from TB and Local Density Approximation (LDA) calculations. Diffusion profiles are produced that were within experimental uncertainty at high boron concentrations. The sheet resistance of boron-doped Si was measured by four-point probes to study the dependence of boron precipitation on temperatures and doping levels. The experiments show that laser annealing can activate boron atoms at concentrations up to 20 times the solid solubility of boron in Si. Loss of conductivity due to the precipitation of boron atoms at moderate annealing temperatures (below 850C) is not pronounced (less than 15%). Thus laser annealing followed by a conventional thermal annealing can provide highly doped and electrically active regions of silicon without the complication of TED.

Luo, Weiwei

2000-10-01

447

Boronization on NSTX using Deuterated Trimethylboron  

SciTech Connect

Boronization on the National Spherical Torus Experiment (NSTX) has proved to be quite beneficial with increases in confinement and density, and decreases in impurities observed in the plasma. The boron has been applied to the interior surfaces of NSTX, about every 2 to 3 weeks of plasma operation, by producing a glow discharge in the vacuum vessel using deuterated trimethylboron (TMB) in a 10% mixture with helium. Special NSTX requirements restricted the selection of the candidate boronization method to the use of deuterated boron compounds. Deuterated TMB met these requirements, but is a hazardous gas and special care in the execution of the boronization process is required. This paper describes the existing GDC, Gas Injection, and Torus Vacuum Pumping System hardware used for this process, the glow discharge process, and the automated control system that allows for remote operation to maximize both the safety and efficacy of applying the boron coating. The administrative requirements and the detailed procedure for the setup, operation and shutdown of the process are also described.

W.R. Blanchard; R.C. Gernhardt; H.W. Kugel; P.H. LaMarche

2002-01-28

448

CVD boron on calcium chromate powder  

SciTech Connect

This study was an experimental effort to improve the compositional homogeneity of a pyrotechnic mixture of boron and calcium chromate (CaCrO/sub 4/). Boron was deposited onto calcium chromate powders at 350/sup 0/C from a diborane and hydrogen gas mixture at a pressure of 40 torr by Chemical Vapor Deposition (CVD). The B:CaCrO/sub 4/ ratio of the coated powders was analyzed by inductively-coupled plasma spectroscopy and the distribution of the two phases was observed by electron microprobe analysis. The pyrotechnic activity was determined by differential thermal analysis. In addition to varying the composition of the mixture, an attempt was made to vary the boron distribution by coating both sized and unsized CaCrO/sub 4/ powders. Boron was deposited for 2 h onto sized CaCrO/sub 4/ powder, which resulted in a higher weight percentage of boron in comparison to the unsized powder. CVD coated CaCrO/sub 4/ powders began their pyrotechnic activity at an auto ignition temperature that was lower than the auto ignition temperature observed for mechanically blended mixtures. The coating of sized CaCrO/sub 4/ powder improved the uniformity of boron deposition of CaCrO/sub 4/, but it also decreased the pyrotechnic activity.

Coonen, R.M.

1984-09-01

449

Determination and Standardization of Analytical Conditions for Dissolved Boron in Coastal Waters of East Sea in Korea by ICP-OES  

NASA Astrophysics Data System (ADS)

The analysis of metals in seawaters has been an important subject for many years. Achieving low-level detection limits as well as overcoming high matrix effect are requested in seawater analysis especially elements of interest are present in various chemical forms. Among them, boron is one of the widely distributed elements in nature and its concentrations of about 10 ppm in the Earth's crust and about 4.5 ppm in the seawater as borates. In seawater boron concentration exhibit a linear relationship to the amount of chloride ion present. Boron had been considered as one of the valuable elements to recover from seawaters for commercial use. Currently, we launched research team for the production of valuable metals from seawaters in Korea that can be used commercially. Several metals including boron were already under serious studies. In this study we aim to prepare standardized operational procedures in analysis of boron during pilot study for boron recovery as pilot recovery process. Inductively coupled plasma Optical Emission Spectrometry (ICP-OES) method is preferred for the analysis of the low levels of boron found in environmental samples such as seawater. In order to develop test method for the determination of dissolved Boron from East Sea Seawater in Korea, all soluble boron present in seawater has been tested and accuracy of measurement was checked from the sampling step. The result of analysis of boron in seawaters presents many difficult problems, ionization of from the alkali and alkaline earth metals. And the problems also exist in handling nebulizer and injector tubes in high saline solutions. The scope of this study was to determine boron which can contain up to 35psu dissolved salt. The work also included comparing various analytical methods for better accurate results in several solution conditions. Dilution, standard addition, matrix matching calibration methods was thoroughly tested differently and detailed operating conditions for using auxiliary gases were also presented.

Yoon, H.; Shin, M.; Yoon, C.; Lee, J.

2005-12-01

450

Influence of boron oxide on protective properties of zinc coating on steel  

SciTech Connect

The authors study the properties of zinc coating when boron oxide is added to the melt for galvanization. The authors found that a rise in the degree of initial deformation of the steel leads to the production of varying thickness of the zinc coating. The results show the favorable influence of small amounts of added boron oxide on the corrosion resistance of a zinc coating on cold-deformed high-carbon steel; this influence is also manifested in the case of deformation of the zinc coating itself.

Alimov, V.I.; Berezin, A.V.

1986-05-01

451

La2O3 Catalyzed C-C Coupling of Aryl Iodides and Boronic Acids  

PubMed Central

An efficient La2O3-catalyzed new route for the carbon-carbon bond formation in particular, symmetrical and unsymmetrical biphenyls has been developed, which proceeds through carbon-carbon coupling reaction of aryl iodides with boronic acids. The reaction provided the desired products in moderate-to-good yields with a wide range of functional group tolerance.

Malik, Payal; Chakraborty, Debashis

2012-01-01

452

Assessing the potential boron toxicity of soils irrigated with reclaimed water in Jordan  

Microsoft Academic Search

Boron (B) is a potentially plant toxic ion and is present in domestic treated wastewater (reclaimed water) in Jordan in concentrations of around 1 mg L-1. As reclaimed water is used for irrigation in Jordan the concentration of B gives potential for detrimental effects on crop productivity. Such effects are dependent on the crop type and importantly, the concentration of

Gemma Carr; Stephen Nortcliff

2010-01-01

453

La2O3 Catalyzed C-C Coupling of Aryl Iodides and Boronic Acids.  

PubMed

An efficient La2O3-catalyzed new route for the carbon-carbon bond formation in particular, symmetrical and unsymmetrical biphenyls has been developed, which proceeds through carbon-carbon coupling reaction of aryl iodides with boronic acids. The reaction provided the desired products in moderate-to-good yields with a wide range of functional group tolerance. PMID:24052852

Malik, Payal; Chakraborty, Debashis

2012-01-01

454

Numerical simulation of vibration performance for nuclear island radioactive boron acid water control valve  

Microsoft Academic Search

On nuclear island radioactive boron acid water control valve vibration characteristics of the process of conducting dynamic analysis of nuclear safety and the important role of the assessment described using finite element analysis product vibration analysis of the practicality of Technology, discussed the use of three-dimensional finite element analysis software-class nuclear safety valve vibration analysis of the basic idea and

Xiao-ming Yu; Liang-wei Zhong; Xian-xia Yue

2010-01-01

455

A boronate-based fluorescent probe for the selective detection of cellular peroxynitrite.  

PubMed

A boronate-based fluorescent probe for the selective monitoring of intracellular peroxynitrite has been developed. The probe takes advantage of the fast reaction of an arylboronate group with peroxynitrite, yielding a corresponding phenol that undergoes spontaneous subsequent reactions to produce a strongly fluorescent product associated with a large turn-on signal. PMID:25002151

Kim, Jiyoung; Park, Jeesook; Lee, Hawon; Choi, Yongdoo; Kim, Youngmi

2014-07-22

456

Conversion electron and X-ray Mssbauer studies of boronized low-carbon steel under corrosion and oxidation conditions  

NASA Astrophysics Data System (ADS)

Iron-boride layers on low-carbon steel were produced by thermochemical diffusion process. The surface interaction products: Fe2B, FeB, FeBx (x>1) and a solid solution of iron in boron were identified by surface Mssbauer spectroscopy (CEMS and XMS). Samples of original and boronized steel were subjected to corrosion process by immersion in HCl (0.1 N) solution for 150 h. While the steel sample was strongly corroded, none corrosion product was found on the boronized sample surface. However, significant changes in relative percentages of the various iron boride phases were detected. Also, samples of original and boronized steel were subjected to oxidation process by heat-treatment in air at 300C for 8 h and 500C for 4 h. At 300C, while bulk Fe3O4 and ?-Fe2O3 were formed on the steel surface, none iron oxide was detected on the boronized surface. At 500 C, while only pure bulk ?-Fe2O3 was detected on the steel surface, a particle size distribution of ?-Fe2O3, with particle size of about 100 , was probably formed on the boronized surface, as evidenced by CEMS.

Abras, A.; Campos, A. A. G.; de Carvalho, A. V.; Ladeira, L. O.

1986-11-01

457

Development of magnetic resonance technology for noninvasive boron quantification  

SciTech Connect

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

Bradshaw, K.M.

1990-11-01

458

Activation of alkynes with B(C?F?)?--boron allylation reagents derived from propargyl esters.  

PubMed

Novel allyl boron compounds are readily synthesized via rearrangement reactions between Lewis acidic B(C6F5)3 and propargyl esters. These reactions proceed through an initial cyclization followed by ring-opening and concurrent C6F5-group migration. In the absence of disubstitution adjacent to the ester oxygen atom, an allyl boron migration rearrangement leads to formal 1,3-carboboration products. These allyl boron compounds act as allylation reagents with aldehydes introducing both a C3-allyl fragment and a C6F5-unit as a single anti-diastereomer. In these reactions, B(C6F5)3 activates the alkynes, prompting the rearrangement processes and enabling installations of C6F5 and R-groups. PMID:24354408

Hansmann, Max M; Melen, Rebecca L; Rominger, Frank; Hashmi, A Stephen K; Stephan, Douglas W

2014-01-15

459

Localized Orbitals in Boron Fluorides. Highly Polarized Boron-Fluorine Double and Triple Bonds.  

National Technical Information Service (NTIS)

The boron fluorides form a class of molecules for which very few theoretical studies of the electronic structures are available. Presented is a localized molecular orbital (LMO) description for the valence structures for the boron fluorides BF, BH2F, BF2H...

J. H. Hall T. A. Halgren D. A. Kleier W. N. Lipscomb

1974-01-01

460

Selective boron drug delivery to brain tumors for boron neutron capture therapy  

Microsoft Academic Search

Malignant glioma is one of the most deadly forms of cancer in humans and remains refractory to presently available treatments. Boron neutron capture therapy (BNCT) is a promising therapeutic modality for the treatment of malignant brain tumors. For successful BNCT, a sufficient quantity of boron atoms must be selectively delivered to individual brain tumor cells while at the same time

Wei Chen; Samir C Mehta; D. Robert Lu

1997-01-01