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1

Boron concentration measurement in biological tissues by charged particle spectrometry.  

PubMed

Measurement of boron concentration in biological tissues is a fundamental aspect of boron neutron capture therapy, because the outcome of the therapy depends on the distribution of boron at a cellular level, besides on its overall concentration. This work describes a measurement technique based on the spectroscopy of the charged particles emitted in the reaction (10)B(n,?)(7)Li induced by thermal neutrons, allowing for a quantitative determination of the boron concentration in the different components that may be simultaneously present in a tissue sample, such as healthy cells, tumor cells and necrotic cells. Thin sections of tissue containing (10)B are cut at low temperatures and irradiated under vacuum in a thermal neutron field. The charged particles arising from the sample during the irradiation are collected by a thin silicon detector, and their spectrum is used to determine boron concentration through relatively easy calculations. The advantages and disadvantages of this technique are here described, and validation of the method using tissue standards with known boron concentrations is presented. PMID:23835595

Bortolussi, S; Altieri, S

2013-07-09

2

Boron isotopic composition and concentration in modern marine carbonates  

Microsoft Academic Search

The boron isotopic compositions and boron concentrations of selected modern marine carbonates were analysed by negative thermal ionization mass spectrometry with a 2 reproducibility of standards and samples better than 0.7%. It was found that the boron isotopic compositions of modern marine carbonates fall within a relatively narrow range (+22.1 ± 3%. relative to NBS SRM951 boric acid standard) for

N. G. Hemming; G. N. Hanson

1992-01-01

3

Abundance and distribution of boron in the Hauzenberg (Bavaria) granite complex  

SciTech Connect

Hercynian S-type granites from the Hauzenberg igneous complex show a range of boron concentration from 1 to 12 ppm. The whole-rock boron data are not significantly correlated with concentrations of other trace elements (Zr, Rb, Ba, Sr, Ni, V, Co, Cu, Zn, F); neither is boron correlated with the major elements (except with sodium) or with the differentiation index (DI). The boron budget in the rock-forming minerals (plagioclase, alkali feldspar, quartz, biotite, muscovite) of the tourmaline-free granites reveals that the highest concentrations of boron occur in muscovite, whereas the greatest amount of boron is incorporated in plagioclase (57-69%) due to its high modal amount. Boron in plagioclase increases with the extent of of sericitization (obtained by X-ray diffractometry). Muscovite in a pegmatite contains more than 50% of the total boron. The areal distribution of boron within the complex is neither uniform nor random; an increase of boron concentrations from granodioritic to granitic rocks is indicated, whereas the late differentiates are depleted in boron.

Sauerer, A.; Troll, G. (Institut fuer Mineralogie und Petrographie der Universitaet Muenchen (Germany, F.R.))

1990-01-01

4

Development of a boron concentration prediction model using multi-cell simulation of the automatic load follow operation  

Microsoft Academic Search

Load follow operations have been performed by manually changing the boron concentration in the reactor core and moving Control Element Assemblies (CEAs) for controlling the power and the power distribution. The manual operation of load follow requires experience and predictions related to core behavior following power changes because CEA movements distort the power distribution and a boron concentration control is

Suk-Whun Sohn; Kun-Jai Lee

2011-01-01

5

Differentiation in boron distribution in adult male and female rats' normal brain: a BNCT approach.  

PubMed

Boron distribution in adult male and female rats' normal brain after boron carrier injection (0.005 g Boric Acid+0.005 g Borax+10 ml distilled water, pH: 7.4) was studied in this research. Coronal sections of control and trial animal tissue samples were irradiated with thermal neutrons. Using alpha autoradiography, significant differences in boron concentration were seen in forebrain, midbrain and hindbrain sections of male and female animal groups with the highest value, four hours after boron compound injection. PMID:22484141

Goodarzi, Samereh; Pazirandeh, Ali; Jameie, Seyed Behnamedin; Khojasteh, Nasrin Baghban

2012-03-30

6

Genetic variation in tolerance to high concentrations of soil boron exists in lentil germplasm  

Microsoft Academic Search

Soils with high concentrations of boron are common in the grain belt of south-eastern Australia. The reduction of soil boron concentration is considered impractical and so the viable alternative is to develop boron tolerant crop cultivars. A glasshouse experiment was conducted with 310 lentil accessions to determine the genetic variation in response to high concentrations of soil boron. The collection

Kristy Hobson; Roger Armstrong; David Connor; Marc Nicolas; Michael Materne

2003-01-01

7

Relationship Between Soil Extractable Boron and Tissue Concentrations in Rosaceae Shrubs in Utah  

Microsoft Academic Search

Native species are distributed among a broad range of soil and environmental conditions and vary widely in boron (B) content. Soil B tests have been used often, but inconsistently, to characterize the supply of B to cultivated crop species; however such tests have never been correlated with B concentrations in native species. This study was designed to determine (a) how

D. Carter; K. T. Harper; A. K. Shiffler; V. D. Jolley; J. K. Harper

2003-01-01

8

Using phosphogypsume and boron concentrator wastes in light brick production  

Microsoft Academic Search

In this study, use of wastes produced in phosphoric acid plants and boron concentrators in producing structural brick has been investigated. There are several parameters involved in using these wastes in brick production namely the rate of added waste, firing speed and firing temperature. The performance of these parameters can be measured by several criteria such as natural drying shortening,

Yüksel Abal?; Mehmet Ali Yurdusev; M. Sadrettin Zeybek; Ahmet Ali Kumanl?o?lu

2007-01-01

9

Variation of Boron Concentration in Metallic Glass Ribbons.  

National Technical Information Service (NTIS)

The surface boron concentration of Fe sub 40 Ni sub 40 P sub 14 B sub 6 , Fe sub 32 Ni sub 36 Cr sub 14 P sub 12 B sub 6 and Fe sub 40 Ni sub 40 B sub 20 metallic glasses was measured by neutron activation analysis on both sides of the ribbon samples. It ...

A. Z. Nagy B. Vasvari P. Duwez L. Bakos Z. Seres

1979-01-01

10

Studies of the Biogeochemistry of Boron. I. Concentrations in Surface Waters, Rainfall and Aquatic Plants.  

National Technical Information Service (NTIS)

Boron concentrations in streams, swamps, ponds and reservoirs of the southeastern United States were usually below 100 ppb. Levels of boron in rainfall varied greatly between different periods of precipitation, but the highest concentrations were observed...

C. E. Boyd W. W. Walley

1971-01-01

11

Study of Precipation and Boron Distribution in 20Cr 25Ni Base Stainless Steels.  

National Technical Information Service (NTIS)

The effect of alloying additions and heat treatment on the microstructural distribution of boron was studied. Eight alloys were investigated, low boron ( 2 wppm) and high boron (containing nominally 300 wppm) versions of a ternary; unstabilized; niobium s...

C. K. Bullough J. K. Jenkins C. A. English

1984-01-01

12

Uranium and boron distributions related to metamorphic microstructure-evidence for metamorphic fluid activity  

Microsoft Academic Search

The distribution of uranium and boron in polymetamorphosed, granulite facies schists and gneisses has been studied using particle track methods. The concentration and distribution of these elements when examined in relation to mineralogy and microstructure provide an insight into: (1) the behaviour of U and B in metamorphism, (2) the activity of a fluid phase in the metamorphic processes and

R. Ahmad; C. J. L. Wilson

1981-01-01

13

Considerations in the determination of boron at low concentrations  

Microsoft Academic Search

Experimental evidence now supports the nutritional essentiality of boron (B) in some biological systems, and accordingly,\\u000a the need for reliable analytical B data is increasing. However, the accurate determination of B in biological materials is\\u000a a formidable challenge at low concentrations (<1 mg B\\/kg). Recent studies still show significant analytical discrepancies\\u000a in the analysis of animal tissues and fluids, despite

R. Gregory Downing; Philip L. Strong; B. Michael Hovanec; Jack Northington

1998-01-01

14

Enhanced blood boron concentration estimation for BPA-F mediated BNCT  

Microsoft Academic Search

The blood boron concentration regulates directly the BNCT irradiation time in which the prescribed dose to the patient is delivered. Therefore a proper estimation of the blood boron concentration for the treatment field based on the measured blood samples before irradiation is required. The bi-exponential model fit using Levenberg—Marquardt method was implemented for this purpose to provide the blood boron

M Kortesniemi; T Seppälä; I Auterinen; S Savolainen

2004-01-01

15

Implantation and Activation of High Concentrations of Boron in Germanium  

SciTech Connect

There is renewed interest in the development of Ge-based devices. Implantation and dopant activation are critical process steps for future Ge devices fabrication. Boron is a common p-type dopant, which remarkably is active immediately after implantation in Ge at low doses. This paper examines the effect of increasing dose (i.e., 5/spl times/10/sup 13/-5/spl times/10/sup 16/ cm/sup -2/) and subsequent annealing (400/spl deg/C-800/spl deg/C for 3 h in nitrogen) on activation and diffusion of boron in Ge. Secondary ion mass spectrometry (SIMS), spreading resistance profiling (SRP), high resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA) are used to characterize the implants before and after annealing. It is found that very high fractions of the boron dose (/spl sim/5%-55%) can be incorporated substitutionally immediately after implantation leading to very high hole concentrations, /spl ges/2/spl times/10/sup 20/ cm/sup -3/, deduced from SRP. Small increases in activation after annealing are observed, however, 100% activation is not indicated by either SRP or NRA. Negligible diffusion after annealing at either 400/spl deg/C or 600/spl deg/C for 3 h was, furthermore, observed.

Suh,Y.; Carroll, M.; Levy, R.; Sahiner, A.; King, C.

2005-01-01

16

Determination of boron distribution in rat's brain, kidney and liver  

Microsoft Academic Search

To determine relative boron distribution in rat's brain, liver and kidney, a mixture of boric acid and borax, was used. After transcardial injection of the solution, the animals were sacrificed and the brain, kidney and liver were removed. The coronal sections of certain areas of the brain were prepared by freezing microtome. The slices were sandwiched within two pieces of

Ali Pazirandeh; Behnam Jameie; Maysam Zargar

2009-01-01

17

Boron acceptor concentration in diamond from excitonic recombination intensities  

Microsoft Academic Search

Excitonic recombinations are investigated by cathodoluminescence in a series of homoepitaxial diamond layers doped with boron in the range (2×1016)-(5×1018)atcm-3. As opposed to earlier observations made on polycrystalline boron-doped diamond, we show that the ratio between the neutral-boron bound exciton and the free-exciton recombination intensities is proportional to the boron content up to 6×1017cm-3 and starts to saturate above this

J. Barjon; T. Tillocher; N. Habka; O. Brinza; J. Achard; R. Issaoui; F. Silva; C. Mer; P. Bergonzo

2011-01-01

18

Study of the Boron Uptake and Distribution in Plant Samples Using a Nondestructive Prompt-Activation Technique  

Microsoft Academic Search

A prompt activation technique – detection of the ?-particles with surface barrier silicon and solid state track detectors, detection of the ? rays with (GeLi) detector – based on the B(n, ?)Li nuclear reaction was applied for boron determination using a time-of-flight technique on the IBR-30 pulsing reactor. The method was used for measurement of the boron concentration and distribution

A. S. Szabó

1981-01-01

19

Fluorescence lifetime measurements of boronate derivatives to determine glucose concentration  

SciTech Connect

A novel investigation into the fluorescence lifetimes of molecules, both established and newly designed, was performed. These molecules are the basis of a continuous, minimally invasive, glucose sensor based on fluorescence lifetime measurements. This sensor, if coupled with an automated insulin delivery device, would effectively create an artificial pancreas allowing for the constant monitoring and control of glucose levels in a person with diabetes. The proposed sensor includes a fluorescent molecule that changes its' fluorescence properties upon binding selectively and reversibly to glucose. One possible sensor molecule is N-methyl-N-(9-methylene anthryl)-2-methylenephenylboronic acid (AB). The fluorescence intensity of AB was shown to change in response to changing glucose concentrations. (James, 1994) James proposed that when glucose binds to AB the fluorescence intensity increases due to an enhancement of the N{yields}B dative bond which prevents photoinduced electron transfer (PET). PET from the amine (N) to the fluorophore (anthracene) quenches the fluorescence. The dative bond between the boron and the amine can prevent PET by involving the lone pair of electrons on the amine in interactions with the boron rather than allowing them to be transferred to the fluorophore. Results of this research show the average fluorescence lifetime of AB also changes with glucose concentration. It is proposed that fluorescence is due to two components: (1) AB with an enhanced N{yields}B interaction, and no PET, and (2) AB with a weak N{yields}B interaction, resulting in fluorescence quenching by PET. Lifetime measurements of AB as a function of both the pH of the solvent and glucose concentration in the solution were made to characterize this two component system and investigate the nature of the N{yields}B bond. Measurements of molecules similar to AB were also performed in order to isolate behavior of specific AB constituents. These molecules are 9-(Methylaminomethyl)-anthracene (MAMA), and N-benzyl-N-methyl-N-methyl anthracene (AB-B). Fluorescence lifetime measurements confirmed the two species of AB, with and without PET. Fluorescence lifetimes were approximately 11 nsec without PET and 3 nsec with PET. The degree of the interaction between the N and the B atoms was also determined by fluorescence lifetime measurements. Electron transfer rates of AB were measured to be on the order of 10{sup 8} sec{sup -1}. Analysis of AB as a glucose sensor shows it has the potential for measuring glucose concentrations in solution with less than 5% error. Two novel glucose sensing molecules, Chloro-oxazone boronate (COB) and Napthyl-imide boronate (NIB), were synthesized. Both molecules have a N{yields}B dative bond similar to AB, but with longer wavelength fluorophores. COB and NIB were found to be unacceptable for use as glucose sensor molecules due to the small changes in average fluorescence lifetime.

Gable, J H

2000-06-01

20

Boron removal and recovery from concentrated wastewater using a microwave hydrothermal method  

Microsoft Academic Search

Boron compounds are widely-used raw materials in industries. However, elevated boron concentrations in aqueous systems may be harmful to human and plants. In this study, calcium hydroxide (Ca(OH)2) alone and Ca(OH)2 with phosphoric acid (H3PO4) addition (P-addition) were used to remove and recover boron from wastewater using hydrothermal methods. A microwave (MW) hydrothermal method was used and compared with the

Hao-Cheng Tsai; Shang-Lien Lo

2011-01-01

21

A bis-boronic acid modified electrode for the sensitive and selective determination of glucose concentrations.  

PubMed

A bis-boronic acid modified electrode for the sensitive and selective determination of glucose concentrations has been developed. The electrochemical characteristics of the sensor with added saccharides were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The bis-boronic acid modified electrode was both sensitive and selective for glucose. PMID:24151634

Wang, Hui-Chen; Zhou, Hao; Chen, Baoqin; Mendes, Paula M; Fossey, John S; James, Tony D; Long, Yi-Tao

2013-10-22

22

Boron and chlorine concentration of volcanic rocks: An application of prompt gamma activation analysis  

Microsoft Academic Search

Summary  Boron and chlorine concentrations in geological standards and in representative volcanic rock samples were determined by prompt gamma activation analysis (PGAA). The results of the GSJ standard measurements proved the high precision of PGAA in measuring the boron, chlorine, other trace elements (Sc, Nd, Sm, and Gd) and the major element contents of the samples. The rock samples originate from

K. Gméling; Sz. Harangi; Zs. Kasztovszky

2005-01-01

23

Biodistribution of boronophenylalanine in patients with glioblastoma multiforme: boron concentration correlates with tumor cellularity.  

PubMed

Boron-10 (10B) concentrations were measured in 107 surgical samples from 15 patients with glioblastoma multiforme who were infused with 95 atom% 10B-enriched p-boronophenylalanine (BPA) intravenously for 2 h just prior to surgery at doses ranging from 98 to 290 mg BPA/kg body weight. The blood 10B concentration reached a maximum at the end of the infusion (ranging from 9.3 to 26.0 microg 10B/g) and was proportional to the amount of BPA infused. The boron concentrations in excised tumor samples ranged from 2.7 to 41.3 microg 10B/g over the range of administered BPA doses and varied considerably among multiple samples from individual patients and among patients at the same BPA dose. A morphometric index of the density of viable-appearing tumor cells in histological sections obtained from samples adjacent to, and macroscopically similar to, the tumor samples used for boron analysis correlated linearly with the boron concentrations. From that correlation it is estimated that 10B concentrations in glioblastoma tumor cells were over four times greater than concurrent blood 10B concentrations. Thus, in the dose range of 98 to 290 mg BPA/kg, the accumulation of boron in tumor cells is a linear function of BPA dose and the variations observed in boron concentrations of tumor specimens obtained surgically are largely due to differences in the proportion of nontumor tissue (i.e. necrotic tissue, normal brain) present in the samples submitted for boron analysis. The tumor:blood 10B concentration ratio derived from this analysis provides a rationale for estimating the fraction of the radiation dose to viable tumor cells resulting from the boron neutron capture reaction based on measured boron concentrations in the blood at the time of BNCT without the need for analysis of tumor samples from individual patients. PMID:9457896

Coderre, J A; Chanana, A D; Joel, D D; Elowitz, E H; Micca, P L; Nawrocky, M M; Chadha, M; Gebbers, J O; Shady, M; Peress, N S; Slatkin, D N

1998-02-01

24

Radiowave dielectric investigation of boron compounds distribution in cultured tumour cells: relevance to boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

The distribution of two main Boron neutron capture therapy (BNCT) agents, borocaptate sodium ( BSH) and borono-phenylalanine ( BPA), in C6 rat glioma cells has been investigated by means of radiowave dielectric spectroscopy measurements. Significant differences between cells treated with the two different boron carriers were found in the magnitude of passive electrical cell parameters. This technique offers a new procedure for the measurement of boron compounds interactions with different biological environments at cellular level and is suggested to have the potentiality for becoming an attractive tool for biodistribution studies of BNCT compounds in biological tissues.

Capuani, S.; Gili, T.; Cametti, C.; Maraviglia, B.; Colasanti, M.; Muolo, M.; Venturini, G.

2002-07-01

25

Boron  

MedlinePLUS

... who do not get much magnesium in their diet. Among younger women, the effect appears to be greater in women ... mg of boron per 2000 kcal per day. Diets considered to be low in boron provide ... pregnant or breast-feeding women over 19 years of age. For adolescents 14 ...

26

Distribution of boron in the Tip Top pegmatite, Black Hills, South Dakota  

SciTech Connect

Experimental evidence has shown the importance of boron on the crystallization behavior of granitic systems; however, the intercrystalline and intracrystalline distribution of boron in mineral phases crystallizing from granitic systems is not well documented. The distribution of boron between coexisting phases in the Tip Top pegmatite, South Dakota, is as follows: beryl ca = quartz ca = triphylite ca = montebrasite ca = potassium feldspar < biotite < albite < muscovite < spodumene << tourmaline. The bulk boron content of the Tip Top pegmatite decreases significantly with the termination of tourmaline crystallization. The significant decrease in boron in the inner zones of the pegmatite is consistent with the depletion of boron in the granite melt by either the crystallization of tourmaline from the granitic melt or the partitioning of boron into an exsolved aqueous solutions. 35 references.

Shearer, C.K.; Papike, J.J.

1986-02-01

27

A ?-ray telescope for on-line measurements of low boron concentrations in a head phantom for BNCT  

Microsoft Academic Search

In Boron Neutron Capture Therapy the 10B(n, ?)7 Li reaction is used to create a tumour-destructing field of high Linear Energy Transfer (LET) particles. The therapy requires a high boron concentration in the tumour and a low boron concentration in the healthy tissue. The boron neutron capture reaction is accompanied by the emission of a photon of energy 478 keV.

W. F. A. R Verbakel; F Stecher-Rasmussen

1997-01-01

28

Study on distribution and origin of boron in groundwater in the area of Chalkidiki, Northern Greece by employing chemical and isotopic tracers.  

PubMed

This paper presents an integrate study on the occurrence and distribution of boron in groundwater in the area of Chalkidiki, Northern Greece. Groundwater samples were collected from wells used for drinking and irrigation purposes. Samples were analysed for boron, various physicochemical parameters (T, pH, EC, Ca, Mg, Na, K, Br, Cl, HCO(3), SO(4), NO(3) and As) and isotopes ((18)O, (2)H, (11)B). Boron showed high spatial variation ranged from 0.04 to 6.5mg/L. Almost 60% of the examined wells exhibited boron concentration higher than the limit of 1mg/L proposed for water intended for human consumption. The higher concentrations were determined in geothermal waters with relatively high temperature. Correlation analysis and hierarchical cluster analysis were employed to find out possible relationships among the examined parameters and groundwater samples. Chemical and isotopic fingerprints have been used to investigate the origin of boron. PMID:19717234

Voutsa, D; Dotsika, E; Kouras, A; Poutoukis, D; Kouimtzis, Th

2009-08-07

29

Behavior of 42 crop species grown in saline soils with high boron concentrations  

Microsoft Academic Search

The coastal region of northern Chile is a desert and the salinity and boron levels in the soils can be high. The irrigation water is also saline (3–9 dS\\/m), with high concentrations of sodium, chloride, and boron. Despite these conditions, the irrigation of alfalfa, winter grains, and vegetables has been practiced on the alluvial soils near the rivers, since before

Raul E. Ferreyra; Agustin U. Aljaro; Rafael Sch. Ruiz; Leonardo P. Rojas; J. D. Oster

1997-01-01

30

Boron Stress and Boron Tissue Distribution in Arbidopsis thaliana and Pelargonium X Hortorum  

Technology Transfer Automated Retrieval System (TEKTRAN)

The micronutrient boron is essential for plant growth and development. Deficient or excessive levels of this micronutrient result in the formation of growth defects that reduce yield in crop plants and result in discarding of horticultural plants. To study the responses of plants to altered boron ...

31

Boron concentration in water, sediment and different organisms around large borate deposits of Turkey.  

PubMed

Boron is an essential nutrient for plants and an essential element for many organisms, but can be toxic to aquatic and terrestrial organisms above certain concentrations. The aim of this research was to determine boron concentrations in water, sediment and biotic samples (Gammaridae spp.-Crustacea, Helix sp.-Gastropoda, Donax sp.-Bivalvia, Helobdella sp.-Hirudinae, Ephemeroptera nymph, Chrinomidae larvae, Tipulidae larvae-Insecta, Rana sp.-Amphibia, Natrix sp.-Serpentes, fish sample Leiscus cephalus (Linnaeus, 1758) and leaves of Salix sp.-Salicacea from Seydi Stream (Kirka-Eski?ehir). Our results have shown that boron concentrations of the Seydi Stream water is higher than the Turkish Environmental Guidelines standard (>1 mg L(-1)) and in Europe (mean values typically below 0.6 mg L(-1)). PMID:20352187

Emiro?lu, Ozgür; Ciçek, Arzu; Arslan, Naime; Aksan, Serdar; Rüzgar, Melih

2010-03-30

32

Subcellular boron and fluorine distributions with SIMS ion microscopy in BNCT and cancer research  

SciTech Connect

The development of a secondary ion mass spectrometry (SIMS) based technique of Ion Microscopy in boron neutron capture therapy (BNCT) was the main goal of this project, so that one can study the subcellular location of boron-10 atoms and their partitioning between the normal and cancerous tissue. This information is fundamental for the screening of boronated drugs appropriate for neutron capture therapy of cancer. Our studies at Cornell concentrated mainly on studies of glioblastoma multiforme (GBM). The early years of the grant were dedicated to the development of cryogenic methods and correlative microscopic approaches so that a reliable subcellular analysis of boron-10 atoms can be made with SIMS. In later years SIMS was applied to animal models and human tissues of GBM for studying the efficacy of potential boronated agents in BNCT. Under this grant the SIMS program at Cornell attained a new level of excellence and collaborative SIMS studies were published with leading BNCT researchers in the U.S.

Subhash Chandra

2008-05-30

33

Direct visualization of boron dopant distribution and coordination in individual chemical vapor deposition nanocrystalline B-doped diamond grains  

NASA Astrophysics Data System (ADS)

The boron dopant distribution in individual heavily boron-doped nanocrystalline diamond film grains, with sizes ranging from 100 to 350 nm in diameter, has been studied using a combination of high resolution annular dark field scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy. Using these tools, the boron distribution and local boron coordination have been determined. Quantification results reveal embedding of B dopants in the diamond lattice, and a preferential enrichment of boron at defective areas and twin boundaries. Coordination mapping reveals a distinct difference in coordination of the B dopants in ``pristine'' diamond areas and in defective regions.

Lu, Ying-Gang; Turner, Stuart; Verbeeck, Johan; Janssens, Stoffel D.; Wagner, Patrick; Haenen, Ken; Van Tendeloo, Gustaaf

2012-07-01

34

Boron deficiency and concentrations and composition of phenolic compounds in Olea europaea leaves: a combined growth chamber and field study.  

PubMed

Boron deficiency is the most frequent micronutrient disorder in olive (Olea spp.) orchards. We tested the hypothesis that plant boron status affects phenolic metabolism, which, in turn, influences several ecophysiological traits of olive (Olea europaea L.) trees, by studying the effects of boron deficiency on leaf phenolic compounds of olive in a growth chamber experiment (CE) and a field experiment (FE). In the CE, a semi-hydroponic system was used to control nutrient supply. Plants received complete nutrient solution containing either 23 (control) or 0 microM H3BO3 (boron-deficient treatment). In the FE, boron-deficient trees were chosen based on visible boron-deficiency symptoms and analysis of their leaf boron concentration. Boron deficiency caused significant accumulation of phenolic compounds in leaves of CE plants (1.7 to 5.8 times more, depending on leaf age), but not in leaves of FE plants. However, in both experiments, the concentration of an unidentified phenolic compound, with a UV-spectrum resembling that of caffeic acid, increased in response to boron deficiency (by a factor of 40 to 184 in the CE and by a factor of three in the FE). Regression analysis showed that the concentration of this compound was negatively correlated to leaf boron concentration, irrespective of growth conditions and treatment. We conclude that, under field conditions, boron deficiency may not be the only factor determining the concentration of total phenolics, but it may be responsible for the accumulation of a distinct phenolic metabolite in olive leaves. PMID:15631979

Liakopoulos, Georgios; Karabourniotis, George

2005-03-01

35

Potential of near infrared spectroscopy to quantify boron concentration in treated wood  

Microsoft Academic Search

Near infrared spectroscopy (NIR) coupled with multivariate statistical methods was assessed as a possible method for de- termining quantitatively boron-based preservative concentration in treated wood. It was found that a NIR-based model could successfully predict the borate concentration of treated pine sapwood cubes, suggesting that it may provide the basis for a rapid, easy-to-operate and portable analytical tool. Borates have

Adam Taylor; Jeff Lloyd

2007-01-01

36

The measurement of thermal neutron flux depression for determining the concentration of boron in blood.  

PubMed

Boron neutron capture therapy (BNCT) is a form of targeted radiotherapy that relies on the uptake of the capture element boron by the volume to be treated. The treatment procedure requires the measurement of boron in the patient's blood. The investigation of a simple and inexpensive method for determining the concentration of the capture element 10B in blood is described here. This method, neutron flux depression measurement, involves the determination of the flux depression of thermal neutrons as they pass through a boron-containing sample. It is shown via Monte Carlo calculations and experimental verification that, for a maximum count rate of 1 x 10(4) counts/s measured by the detector, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 32 +/- 2 min. For a source activity of less than 1.11 x 10(11) Bq and a maximum count rate of less than 1 x 10(4) counts/s, a 10 ppm 10B sample of volume 20 ml can be measured with a statistical precision of 10% in 58 +/- 3 min. It has also been shown that this technique can be applied to the measurement of the concentration of any element with a high thermal neutron cross section such as 157Gd. PMID:11277219

Brooke, S L; Green, S; Charles, M W; Beddoe, A H

2001-03-01

37

Detailed dose distribution prediction of Cf-252 brachytherapy source with boron loading dose enhancement.  

PubMed

The purpose of this work is to evaluate the dose rate distribution and to determine the boron effect on dose rate distribution for (252)Cf brachytherapy source. This study was carried out using a Monte Carlo simulation. To validate the Monte Carlo computer code, the dosimetric parameters were determined following the updated TG-43 formalism and compared with current literature data. The validated computer code was then applied to evaluate the neutron and photon dose distribution and to illustrate the boron loading effect. PMID:19889549

Ghassoun, J; Mostacci, D; Molinari, V; Jehouani, A

2009-10-14

38

Differences in Shoot Boron Concentrations, Leaf Symptoms, and Yield of Turkish Barley Cultivars Grown on Boron?Toxic Soil in Field  

Microsoft Academic Search

Using 10 barley Turkish cultivars (Hordeum vulgare L.) field experiments were carried out on soils containing normal and very high soluble boron (B) concentration to study genotypic variation in tolerance to B toxicity in soil and the relationships between the shoot or leaf concentrations of B, severity of B?toxicity symptoms and yield. As judged by differences in degree of severity

B. Torun; M. Kalayci; L. Ozturk; A. Torun; M. Aydin; I. Cakmak

2002-01-01

39

Serum boron concentration from inhabitants of an urban area in Japan  

Microsoft Academic Search

Boron (B) levels were determined in the serum of 980 healthy inhabitants living in an urban area of Japan by means of inductively\\u000a coupled plasma emission spectrometry (ICPES).\\u000a \\u000a The results showed a log-normal distribution of serum B for both sexes, although there are age-related differences. In male\\u000a subjects, serum B increases rapidly up to 49 yr of age, reaching a

Kan Usuda; Koichi Kono; Yasuhisa Yoshida

1997-01-01

40

Oxyanion Concentrations in Eastern Sierra Nevada Rivers – 3. Boron, Molybdenum, Vanadium, and Tungsten  

Microsoft Academic Search

Water samples were collected from 10 locations along the Truckee River system, 14 locations along the Walker River system, and 12 locations along the Carson River, and analyzed for B, Mo, V, W, Na, Cl, and pH. Boron concentrations ranged from approximately 2 µmol\\/kg in the upper reaches of the Truckee River to almost 1,200 µmol\\/kg in Pyramid Lake. Molybdenum,

Kevin H. Johannesson; W. Berry Lyons; Elizabeth Y. Graham; Kathleen A. Welch

2000-01-01

41

Toward prompt gamma spectrometry for monitoring boron distributions during extra corporal treatment of liver metastases by boron neutron capture therapy: a Monte Carlo simulation study.  

PubMed

A Monte Carlo calculation was carried out for boron neutron capture therapy (BNCT) of extra corporal liver phantom. The present paper describes the basis for a subsequent clinical application of the prompt gamma spectroscopy set-up aimed at in vivo monitoring of boron distribution. MCNP code was used first to validate the homogeneity in thermal neutron field in the liver phantom and simulate the gamma ray detection system (collimator and detector) in the treatment room. The gamma ray of 478 keV emitted by boron in small specific region can be detected and a mathematical formalism was used for the tomography image reconstruction. PMID:19394243

Khelifi, R; Nievaart, V A; Bode, P; Moss, R L; Krijger, G C

2009-04-02

42

Metastable boron active concentrations in Si using flash assisted solid phase epitaxy  

NASA Astrophysics Data System (ADS)

There has been considerable interest recently, in the formation of the source drain junctions of metal oxide semiconductor transistors using solid phase epitaxy (SPE) to activate the dopants rather than a traditional high temperature anneal. Previous studies have shown that this method results in high dopant activation as well as shallow junctions (due to the small thermal budget). In this we study the effect the temperature of SPE regrowth has on the boron activation. We find that boron activation has a monotonically increasing dependence on the temperature. Significantly, we show that by carrying out the SPE regrowth at temperatures above 1050 °C, it is possible to obtain active concentrations well above the electrical solubility limits.

Jain, S. H.; Griffin, P. B.; Plummer, J. D.; McCoy, S.; Gelpey, J.; Selinger, T.; Downey, D. F.

2004-12-01

43

Depth distribution of boron determined by slow neutron induced lithium ion emission  

Microsoft Academic Search

Neutron Depth Profiling (NDP) has been established as a non-destructive technique to determine the near surface distribution of light elements, particularly boron. By analyzing the residual energy spectrum of the emitted particles of known initial energy as a result of nuclear capture within the target material, information about the site and amount of the reactions can be deduced. In the

Huaiyu H. Chen-Mayer; George P Lamaze

1998-01-01

44

Boron Concentrations in Milk from Mothers of Exclusively Breast-Fed Healthy Full-Term Infants Are Stable during the First Four Months of Lactation1,2  

Microsoft Academic Search

Because boron is a bioactive element that satisfies several of the criteria for essentiality in humans, the aim of the present work was to determine the profile of boron metabolism in human milk during the first 4 mo of lactation. The concentration of boron and other minerals was determined in archived milk collected (1980-84) 1 time\\/mo for 4 mo from

Curtiss D. Hunt; Nancy F. Butte; LuAnn K. Johnson

45

Sequential rat blood boron concentration measurements method using CR-39 SSNTDs  

SciTech Connect

Boron neutron capture therapy (BNCT) has been used as an experimental modality for the treatment of a highly malignant form of human brain cancer, glioblastoma multiforme. The success of BNCT is currently being tested at our institution using an anaplastic glioma clone transplanted into the caudate nucleus of Fischer rats, as a model for glioblastoma multiforme in humans. Since the blood boron concentration at the time of neutron irradiation must be low in order for BNCT to be successful, we have developed a solid-state nuclear track detector (SSNTD)-based sequential assay technique for measuring {sup 10}B concentrations in the blood of rats. With our technique, many blood samples can be taken from a single rat, thus reducing the uncertainty at different time points, due to biological variability among rats, which is inherent is assay techniques with which one can obtain only one data point per rat. The purpose of this paper is to describe the assay technique and to illustrate its usefulness by providing representative data from an ongoing pharmacokinetic study.

Mengers, T.F.; Blue, T.E.; Curran, J.F.; Carey, W.E.; Barth, R.F.

1988-01-01

46

Effects of Boron Application on Yield, Foliar Boron Concentration, and Efficiency of Soil Boron Extracting Solutions in a Xanthic Ferralsol Cultivated with Banana in Central Amazon  

Microsoft Academic Search

Boron (B) is known to play important roles in the structures of cell walls and membranes and in the integrity and functions of membranes in plants. Under the conditions in the central Amazon region, there are few studies about this nutrient. In Brazilian soils, the hot-water B extraction method has been extensively used for evaluation of soil B status. However,

A. Moreira; C. Castro; N. K. Fageria

2011-01-01

47

PET pharmacokinetic analysis to estimate boron concentration in tumor and brain as a guide to plan BNCT for malignant cerebral glioma  

Microsoft Academic Search

Introduction: To plan the optimal BNCT for patients with malignant cerebral glioma, estimation of the ratio of boron concentration in tumor tissue against that in the surrounding normal brain (T\\/N ratio of boron) is important. We report a positron emission tomography (PET) imaging method to estimate T\\/N ratio of tissue boron concentration based on pharmacokinetic analysis of amino acid probes.Methods:

Tadashi Nariai; Kiichi Ishiwata; Yuichi Kimura; Motoki Inaji; Toshiya Momose; Tetsuya Yamamoto; Akira Matsumura; Kenji Ishii; Kikuo Ohno

2009-01-01

48

Effect of boron concentration on the UV photosensitivity of silica glass film for planar lightwave circuit  

NASA Astrophysics Data System (ADS)

The photosensitivity dynamics in SiO 2 glass with a composition similar to that of silica planar lightwave circuit (PLC) devices was investigated as a fundamental study prior to device fabrication. Silica bulk glasses with similar composition to the core layer of PLC devices were prepared with various concentrations of B 2O 3. The photosensitivity in boron and germanium co-doped amorphous SiO 2 yields a refractive index change ? n as high as 10 -3 after irradiation with a KrF UV laser beam. The index modulation disappeared after thermal annealing. The result of annealing experiment and UV absorption/Raman spectra revealed that the molar volume change by UV irradiation is responsible for the index variation in the material.

Shin, Dongwook

2007-07-01

49

Distribution of Foliar-applied Boron Measured by Spark-source Mass Spectrometry and Laser-probe Mass Spectrography  

PubMed Central

The distribution of foliar-applied boron ([10B]boric acid) in radish (Raphanus sativus L.) was studied using for analysis of the stable isotopes a technique allowing a high sensitivity: spark-source mass spectrometry. Boron was recovered in the nontreated aerial parts and in the roots; however, the greatest fraction was in the treated leaf. It was possible with a laser-probe mass spectrograph to show that boron was not superficially located in the treated area but was present in tissues at all levels of depth considered. Images

Chamel, Andre R.; Andreani, Anne-Marie; Eloy, Jean-Francois

1981-01-01

50

High concentrations of fluoride and boron in drinking water wells in the Muenster region--results of a preliminary investigation.  

PubMed

In 1998, two cases of severe dental fluorosis in schoolchildren occurred in the Muenster region. These cases took place in one household, where fluoridated toothpaste, fluoridated salt, and fluoride tablets were consumed. Furthermore, the family used drinking water from its private well only. Analyses of the well water ordered by local health officials revealed very high amounts of fluoride, boron, and other electrolytes. This unusual combination of high amounts of fluoride and boron could also be found in the water of a great number of other private wells that are the only source for drinking water in this rural region of the Muensterland. Anthropogenic sources could be excluded. Because of this, the results of the water samples were collated to the specific geological situation in this area. In the Muenster region there are marl layers of the chalk era covered with quarternary sediments. The quarternary sediments are up to 10 to 20 metres thick and they usually conduct the groundwater. The marl contains high concentrations of fluoride and boron. In some places the groundwater has contact with these layers. To check the amount of fluoride and boron in the groundwater, indicator values were sought, which can give a hint of high contents of these trace elements. In this study the conductivity and acidity were identified as possible indicators of a high amount of fluoride and boron in the drinking water in this specific region. To work economically and efficiently, the drinking water should be checked for fluoride and boron on a regular basis only when these values are extraordinarily high. In the case of high concentrations, especially of fluoride, in the drinking water the persons concerned should be informed about their potential health risk, giving them the opportunity to optimise the total daily intake of fluoride. PMID:11279818

Queste, A; Lacombe, M; Hellmeier, W; Hillermann, F; Bortulussi, B; Kaup, M; Ott, K; Mathys, W

2001-03-01

51

Chemical mechanical polishing of PSG and BPSG dielectric films: the effect of phosphorus and boron concentration  

Microsoft Academic Search

Chemical-mechanical polishing of blanket and patterned oxide films doped with phosphorus and boron has been studied. FTIR was used to characterize the film microstructure. Experimental results show that an increase of phosphorus level promoted the polish rate of PSG film. We also found that increasing the boron content enhanced the polish rate of BPSG films although phosphorus contents is decreased.

Chi-Wen Liu; Bau-Tong Dai; Ching-Fa Yeh

1995-01-01

52

Characterization of electrodeposited elemental boron  

Microsoft Academic Search

Elemental boron was produced through electrowinning from potassium fluoroborate dissolved in a mixture of molten potassium fluoride and potassium chloride. The characteristics of the electrodeposited boron (raw boron) as well as the water and acid-leached product (processed boron) were studied. The chemical purity, specific surface area, size distribution of particles and X-ray crystallite size of the boron powders were investigated.

Ashish Jain; S. Anthonysamy; K. Ananthasivan; R. Ranganathan; Vinit Mittal; S. V. Narasimhan; P. R. Vasudeva Rao

2008-01-01

53

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

54

The response of trout and zebrafish embryos to low and high boron concentrations is U-shaped  

Microsoft Academic Search

Fish in the embryo-larval stage of development have been shown to be sensitive to boron (B) at both ends of the dose-response\\u000a curve (1,2). The present study evaluated the health effects of low and high B concentrations on rainbow trout (Oncorhynchus mykiss), a cold water species, and zebrafish (Danio rerio), a warm water species. Rainbow trout embryos were incubated from

Ruby I. Rowe; Collen Bouzan; Sam Nabili; Curtis D. Eckhert

1998-01-01

55

Studies on distribution of element contents in transient layer at interface between boron-doped diamond film electrode and tantalum substrate  

NASA Astrophysics Data System (ADS)

The boron-doped diamond film (BDD) grown on tantalum (Ta) substrate as an electrode (BDD/Ta) was prepared by hot filament chemical vapor deposition method. The experimental results demonstrated that our BDD/Ta had high current efficiency, strong ability to degrade wastewater, good corrosion stability and long lifetime. These excellent characteristics of BDD/Ta have been explained in terms of Rutherford backscattering (RBS) experiments. RBS investigation revealed that the continuous transient layer at the interface between boron-doped diamond film and Ta-substrate was formed and the microstructure of the continuous transient layer given by the continuous distribution of all element contents at the interface was obtained. The thicknesses of boron-doped diamond film and the continuous transient layer were about equal to 8000 × 10 15 atoms/cm 2 and 5800 × 10 15 atoms/cm 2, respectively. The formation of the continuous transient layer at the interface can eliminate the mismatch of thermal expansion coefficients (TEC) at the interface and only lead to the slow change of TEC because of the continuous distribution of element contents of the film and substrate in the transient layer at the interface. Thus, there is no residual stress to concentrate on the interface and the stress-corrosion delamination of the film disappears. Therefore, the corrosion stability and lifetime of BDD/Ta increase and last well, that have been verified by X-ray diffraction (XRD) experiments.

Liang, Jiachang; Gao, Chengyao; Zhang, Liping; Jiang, Lihui; Yang, Zhengquan; Wang, Zhiping; Ji, Chaohui; Le, Xiaoyun; Rong, Cuihua; Zhang, Jian

2011-05-01

56

Feasibility of boron neutron capture therapy (BNCT) for malignant pleural mesothelioma from a viewpoint of dose distribution analysis  

Microsoft Academic Search

Purpose: To investigate the feasibility of boron neutron capture therapy (BNCT) for malignant pleural mesothelioma (MPM) from a viewpoint of dose distribution analysis using Simulation Environment for Radiotherapy Applications (SERA), a currently available BNCT treatment planning system. Methods and Materials: The BNCT treatment plans were constructed for 3 patients with MPM using the SERA system, with 2 opposed anterior-posterior beams.

Minoru. Suzuki; Yoshinori Sakurai; Shinichiro Masunaga; Yuko Kinashi; Kenji Nagata; Akira Maruhashi; Koji Ono

2006-01-01

57

Cultivar differences in boron uptake and distribution in celery (Apium graveolens), tomato (Lycopersicon esculentum) and wheat (Triticum aestivum)  

Microsoft Academic Search

Species and cultivar differences in boron (B) uptake at low B availability and tolerance to high external B are known for many species but mechanisms explaining such differences remain obscure. Here we contrast B uptake and distribution between two cultivars of tomato and celery that differ significantly in their susceptibility to B deficiency. The celery cultivar S48-54-1 and tomato cultivar

Nacer Bellaloui; Patrick H. Brown

1998-01-01

58

Methods for radiation dose distribution analysis and treatment planning in boron neutron capture therapy  

SciTech Connect

This article presents a survey of recent progress in the development and application of analytical methods for calculating macroscopic and microscopic radiation dose distributions for Boron Neutron Capture Therapy (BNCT). Such calculations are an essential component of in vivo BNCT research and will ultimately also be required for human BNCT treatment planning. Calculations of macroscopic absorbed dose distributions for BNCT are more complex than for photon therapy. There are several different dose components, each of which has its own characteristic spatial distribution, linear energy transfer, and relative biological effectiveness (RBE). Three-dimensional (3-D) energy-dependent radiation transport models with a detailed treatment of particle scattering are required. Geometric descriptions for such models are typically constructed directly from medical image data and both the Monte Carlo stochastic simulation method and the discrete-ordinates deterministic approach have been successfully used to perform the necessary radiation transport calculations. Microdosimetric effects can profoundly influence the therapeutic benefit that may be attainable in BNCT. These effects must be carefully taken into account in the interpretation dose. Calculations of microdosimetric parameters for BNCT are typically performed using the Monte Carlo method to generate single-event energy deposition frequency distributions for critical targets in various cell types of interest. This information is useful in the development of apparent RBE factors, or [open quotes]compound factors[close quotes] for the various dose components in BNCT. 31 refs., 15 figs., 1 tab.

Nigg, D.W. (Idaho National Engineering Lab. EG G, Idaho Falls, ID (United States))

1994-03-30

59

Quantitative imaging of boron, calcium, magnesium, potassium, and sodium distributions in cultured cells with ion microscopy.  

PubMed

A method for the conversion of intensity information in ion micrographs of freeze-fractured, freeze-dried cultured cells to local dry weight elemental concentrations is presented. Homogenates generated from cultured cells are used as calibration standards. Ion microscope (IM) relative sensitivity factors for B, Ca, K, Mg, and Na with respect to the matrix element C are determined by the correlation of IM and inductively coupled plasma atomic emission spectrometry analyses of the cellular homogenates. After calibration of the IM imaging system, the relative sensitivity factors are used to determine local intracellular concentrations of B, Ca, K, Mg, and Na in cultured Swiss 3T3 fibroblasts. Intracellular B was introduced through cellular uptake of Na2B12H11SH, a candidate therapeutic agent for boron neutron capture cancer therapy. The IM intracellular concentration results show good agreement with published electron probe X-ray microanalysis results. Estimated detection limits are in the low- to subparts-per-million dry weight concentration range. PMID:2619055

Ausserer, W A; Ling, Y C; Chandra, S; Morrison, G H

1989-12-15

60

Boron in chondritic meteorites  

Microsoft Academic Search

Alpha-track images (ATI), prepared by etching neutron-irradiated cellulose nitrate films attached to polished thin sections of meteorites, provide useful qualitative maps of boron and lithium distribution. However, extreme care must be taken to avoid contamination during preparation, particularly by boron in diamond polishing paste. Boron and lithium are virtually absent from chondrules, metal and sulfide grains in carbonaceous and ordinary

D. M. Shaw; M. D. Higgins; R. W. Hinton; M. G. Truscott; T. A. Middleton

1988-01-01

61

On processes controlling the distribution and fluxes of boron in natural waters and air along transects across the South Island of New Zealand  

Microsoft Academic Search

The concentrations of boron were measured in rain, air and soil water along transects across the Southern Alps, New Zealand, during southern autumn and early winter 1999. Estimates of wet deposition, dry deposition, and flux of boron leaving the soil in soil water are presented. At the Main Divide of the Southern Alps, strong and constant orographic effects on rain-bearing

Reimer Herrmann

2001-01-01

62

Subtle changes in rhizosphere microbial community structure in response to increased boron and sodium chloride concentrations  

Microsoft Academic Search

Two of the major constraints to grain production in large areas of South-East Australia and cropping soils worldwide are high levels of subsoil boron (B) and excessive salinity (NaCl). Although the effect of these constraints is often studied in plants, the effect on microbially mediated plant-beneficial processes is unclear. To that end, we investigated the impact of B and NaCl

Darryl R. Nelson; Pauline M. Mele

2007-01-01

63

Developmental effects of boric acid in rats related to maternal blood boron concentrations  

Microsoft Academic Search

Timed-mated Sprague-Dawley rats (60\\/group) were exposed to boric acid (BA) from gestational days (gd) 0 to 20. BA added to\\u000a the diet (0, 0.025, 0.050, 0.075, 0.1, or 0.2%) yielded boron (B) intakes of <0.35 (control), 3, 6,10,13, or 25 mg B\\/kg body\\u000a wt\\/d. Approximately one-half of the dams\\/group were terminated on gd 20, maternal whole blood collected and frozen,

Catherine J. Price; Philip L. Strong; F. Jay Murray; Margaret M. Goldberg

1998-01-01

64

Grain boundary segregation of boron in an austenitic stainless steel  

NASA Astrophysics Data System (ADS)

A combination of transmission electron microscopy, field-ion microscopy, and atom-probe microanalysis was used to study grain boundary segregation of boron and its influence on the elemental distribution in the boundary region in AISI type 304 (UNS S30400) austenitic stainless steel. Non-equilibrium segregation of boron is shown to prevail with a maximum concentration at the grain boundary and a tail of decreasing concentration away from the boundary. The effects of boron segregation on the elemental distribution of carbon, phosphorus, and chromium are also discussed.

Carinci, Gary M.

1994-03-01

65

Modeling Boron Adsorption on Kaolinite  

Microsoft Academic Search

Boron adsorption at constant ionic strength (0.09 _+ 0.01 moles\\/liter of KC10, or Ca(C104)2) on 0.2-2 #m clay fraction of pretreated kaolinite was modeled using both phenomenological equations and surface complexation reactions. Phenomenological equations were expressed as linear relationships between the distribution coefficient and adsorption density or equilibrium concentration. The normalized form of the isotherms allowed the distribution coefficient to

Shivi P. N. Singh

1992-01-01

66

Boron in soils and plants of the West Transbaikal region  

NASA Astrophysics Data System (ADS)

Some particularities of the distribution of boron in the main types of soils were studied. A close dependency between the boron content in the soils and its concentration in the soil-forming rocks ( r = 0.85) was established, as well as the absence of a correlation between the content of boron and that of humus. It was found that boron is an element with an average intensity of accumulation in plants: the coefficient of its biological absorption from the soil of the steppe, meadow, and agrocenoses varied from 1.2 to 3.2. A correlation between the bulk content of boron in the soils and its accumulation in plants was absent ( r = -0.07-0.11). The vegetation of a significant part of the steppe, dry-steppe, and forest-steppe landscapes had a boron deficiency (30-75%).

Kashin, V. K.

2012-04-01

67

Feasibility of boron neutron capture therapy (BNCT) for malignant pleural mesothelioma from a viewpoint of dose distribution analysis  

SciTech Connect

Purpose: To investigate the feasibility of boron neutron capture therapy (BNCT) for malignant pleural mesothelioma (MPM) from a viewpoint of dose distribution analysis using Simulation Environment for Radiotherapy Applications (SERA), a currently available BNCT treatment planning system. Methods and Materials: The BNCT treatment plans were constructed for 3 patients with MPM using the SERA system, with 2 opposed anterior-posterior beams. The {sup 1}B concentrations in the tumor and normal lung in this study were assumed to be 84 and 24 ppm, respectively, and were derived from data observed in clinical trials. The maximum, mean, and minimum doses to the tumors and the normal lung were assessed for each plan. The doses delivered to 5% and 95% of the tumor volume, D{sub 05} and D{sub 95}, were adopted as the representative dose for the maximum and minimum dose, respectively. Results: When the D{sub 05} to the normal ipsilateral lung was 5 Gy-Eq, the D{sub 95} and mean doses delivered to the normal lung were 2.2-3.6 and 3.5-4.2 Gy-Eq, respectively. The mean doses delivered to the tumors were 22.4-27.2 Gy-Eq. The D{sub 05} and D{sub 95} doses to the tumors were 9.6-15.0 and 31.5-39.5 Gy-Eq, respectively. Conclusions: From a viewpoint of the dose-distribution analysis, BNCT has the possibility to be a promising treatment for MPM patients who are inoperable because of age and other medical illnesses.

Suzuki, Minoru [Particle Oncology Research Center, Osaka (Japan)]. E-mail: msuzuki@rri.kyoto-u.ac.jp; Sakurai, Yoshinori [Division of Medical Physics, Department of Radiation Life Science, Research Reactor Institute, Kyoto University, Osaka (Japan); Masunaga, Shinichiro [Particle Oncology Research Center, Osaka (Japan); Kinashi, Yuko [Particle Oncology Research Center, Osaka (Japan); Nagata, Kenji [Particle Oncology Research Center, Osaka (Japan); Maruhashi, Akira [Division of Medical Physics, Department of Radiation Life Science, Research Reactor Institute, Kyoto University, Osaka (Japan); Ono, Koji [Particle Oncology Research Center, Osaka (Japan)

2006-12-01

68

Fabrication of boron articles  

DOEpatents

This invention is directed to the fabrication of boron articles by a powder metallurgical method wherein the articles are of a density close to the theoretical density of boron and are essentially crackfree. The method comprises the steps of admixing 1 to 10 weight percent carbon powder with amorphous boron powder, cold pressing the mixture and then hot pressing the cold pressed compact into the desired article. The addition of the carbon to the mixture provides a pressing aid for inhibiting the cracking of the hot pressed article and is of a concentration less than that which would cause the articles to possess significant concentrations of boron carbide.

Benton, Samuel T. (Knoxville, TN)

1976-01-01

69

Boron concentrations in milk from mothers of exclusively breast-fed healthy full-term infants are stable during the first four months of lactation.  

PubMed

Because boron is a bioactive element that satisfies several of the criteria for essentiality in humans, the aim of the present work was to determine the profile of boron metabolism in human milk during the first 4 mo of lactation. The concentration of boron and other minerals was determined in archived milk collected (1980-84) 1 time/mo for 4 mo from lactating mothers of full-term, exclusively breast-fed infants living in Houston, TX. A linear model (treating month as a continuous variable) indicated that B concentrations were stable (P = 0.14) between mo 1 [3.88 +/- 0.6 mumol (42 +/- 6.5 microg)/L milk] and 4 [3.24 +/- 0.6 micromol (35 +/- 6.5 microg)/L milk, mean +/- SEM]. Mg concentrations increased slightly over time (1.18 +/- 0.09 to 1.36 +/- 0.09 mmol/L, P < 0.0001), whereas Ca concentrations decreased slightly (7.01 +/- 0.29 to 6.68 +/- 0.29 mmol/L milk, P < 0.02) and Zn decreased substantially (0.04 +/- 0.004 to 0.02 +/- 0.004 mmol/L milk, P < 0.0001). Similarities in findings reported here and earlier (from samples collected in St. John's, Newfoundland) provide further evidence that boron may be metabolically regulated. Future investigations of boron regulatory mechanisms should focus on metabolism of bone as the major storage site of B and kidney excretion, the major excretory route for B. PMID:16177200

Hunt, Curtiss D; Butte, Nancy F; Johnson, LuAnn K

2005-10-01

70

Concentration of cesium and francium by distribution and adsorption chromatography  

Microsoft Academic Search

Methods were developed for concentrating cesium and francium from nuclear reaction products using distribution and adsorption\\u000a chromatography. The feasibility of obtaining concentrated solutions of cesium and francium, both on carriers and carrier-free,\\u000a has been demonstrated.

N. S. Maltseva; K. A. Gavrilov

1972-01-01

71

Vertical distribution of atmospheric aerosol concentration at xianghe  

Microsoft Academic Search

This paper summarizes atmospheric aerosol concentrations of 5 stratospheric balloon soundings during the period from 1984 to 1994. Aerosol-rich layers in the troposphere were detected and the causes were analyzed. The main results are as follows: (1) the vertical distribution of the atmospheric aerosol is affected by atmospheric dynamic processes, humidity, etc.; (2) the tropospheric column concentrations of aerosol were

Li Xu; Guangyu Shi; Jun Zhou; Yasunobu Iwasaka

2004-01-01

72

Electrochemical oxidation of reverse osmosis concentrate on boron-doped diamond anodes at circumneutral and acidic pH.  

PubMed

Electrochemical processes have been widely investigated for degrading organic contaminants present in wastewater. This study evaluated the performance of electrochemical oxidation using boron-doped diamond (BDD) electrodes by forming OH() for the treatment of reverse osmosis concentrate (ROC) from secondary-treated wastewater effluents. Since oxidation by OH() and active chlorine species (HClO/ClO(-)) is influenced by pH, the electrochemical oxidation of ROC was evaluated at controlled pH 6-7 and at pH 1-2 (no pH adjustment). A high concentration of chloride ions in the ROC enhanced the oxidation, and 7-11% of Coulombic efficiency for chemical oxygen demand (COD) removal was achieved with 5.2 Ah L(-1) of specific electrical charge. Complete COD removal was observed after 5.2 and 6.6 Ah L(-1), yet the corresponding dissolved organic carbon (DOC) removal was only 48% (at acidic pH) and 59% (at circumneutral pH). Although a higher operating pH seemed to enhance the participation of OH() in oxidation mechanisms, high concentrations of chloride resulted in the formation of significant concentrations of adsorbable organic chlorine (AOCl) after electrochemical oxidation at both pH. While adsorbable organic bromine (AOBr) was degraded at a higher applied electrical charge, a continuous increase in AOCl concentration (up to 0.88 mM) was observed until the end of the experiments (i.e. 10.9 Ah L(-1)). In addition, total trihalomethanes (tTHMs) and total haloacetic acids (tHAAs) were further degraded with an increase in electrical charge under both pH conditions, to final total concentrations of 1 and 4 ?M (tTHMs), and 12 and 22 ?M (tHAAs), at acidic and circumneutral pH, respectively. In particular, tHAAs were still an order of magnitude above their initial concentration in ROC after further electrooxidation. Where high chloride concentrations are present, it was found to be necessary to separate chloride from ROC prior to electrochemical oxidation in order to avoid the formation of chlorinated by-products. PMID:22995242

Bagastyo, Arseto Y; Batstone, Damien J; Kristiana, Ina; Gernjak, Wolfgang; Joll, Cynthia; Radjenovic, Jelena

2012-09-06

73

Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme  

SciTech Connect

Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, {alpha}) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg {sup 10}B/g blood.

Zasneda, Sabriani; Widita, Rena [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung, 40132 (Indonesia)

2010-06-22

74

Influence of boron concentration on growth characteristic and electro-catalytic performance of boron-doped diamond electrodes prepared by direct current plasma chemical vapor deposition  

Microsoft Academic Search

A series of boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) with different compositions of CH4\\/H2\\/B(OCH3)3 gas mixture. A maximum growth rate of 0.65mgcm?2h?1 was obtained with CH4\\/H2\\/B(OCH3)3 radio of 4\\/190\\/10 and this growth condition was also a turning point for discharge plasma stability which arose from the addition of B(OCH3)3 that changed electron

Yujie Feng; Jiangwei Lv; Junfeng Liu; Na Gao; Hongyan Peng; Yuqiang Chen

2011-01-01

75

Boron Concentration Evolution in the Temporary Curtains of a BWR Reactor. BURCUR Code.  

National Technical Information Service (NTIS)

The theoretical model and the user's guide of the code BURCUR is included. This code analyzes the burnable poison concentration of the temporary curtains as a function of time, for BWR reactors of the 7 x 7 design. The computing time being reasonably shor...

M. Cano Aguado J. M. Perlado Martin E. Minguez Torres

1977-01-01

76

Pre-irradiation spatial distribution and stability of boride particles in rapidly solidified boron-doped stainless steels  

SciTech Connect

The time temperature behavior of boride particles has been studied in rapidly solidified ultra low carbon and nitrogen modified 316 stainless steel with 0.088% boron and 0.45% zirconium. The results show that the as-splat-cooled specimens exhibit precipitates at the grain boundaries and triple junctions. For temperatures up to about 750/sup 0/C no significant microstructural changes occur for short heat treatment times. In the temperature range of 750 to 950/sup 0/C, however, particles typically 100 to 500 A in diameter containing Zr and B are formed within the grains. Higher temperatures enhance the formation of such particles and give rise to particle networks. The results show that a fine and uniform distribution of the boride particles almost exclusively within the grains can be achieved if proper annealing conditions are chosen. This type of distribution is an important requirement for the homogeneous production of helium during neutron irradiation in fast reactors.

Kanani, N.; Arnberg, L.; Harling, O.K.

1981-01-01

77

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

78

Boron partitioning in the upper mantle: An experimental and ion probe study  

NASA Astrophysics Data System (ADS)

Piston cylinder experiments were performed on two natural spinel lherzolites, from Lherz (French Pyrénées) and Kilbourne Hole (USA), in order to determine the distribution coefficients of boron between minerals and melt for upper mantle conditions. Additionally, a MORB glass and its phenocrysts were taken as a low pressure analogue. Boron concentration measurements were made by ion probe, the only technique suitable for in situ (˜ 10 ?m) boron concentration measurements in the range 0.1-1 ppm. The two starting peridotites samples have low bulk boron concentrations of 0.96 and 0.81 ppm. Boron distribution coefficients were determined from (1) direct measurement of melt and crystals in contact, and (2) calculations from profiles of several tens of measurements made using 10?m diameter spots containing variable proportions of crystals and melt. Distribution coefficients between minerals and melt decrease in the following order: Dcpx-melt (0.117) > Dsp-melt (0.08) ? Dol-melt (0.034) > = Dopx-melt (0.027). The limited ranges of composition, pressure, and temperature investigated mimic natural conditions for basalt genesis but sharply limit the present data for determining variations of partition coefficients with P, T, and X. However, boron behavior seems to follow roughly that of aluminum, since the Al-richest minerals are the ones with the highest boron distribution coefficients. The Dol-melt values increase with pressure, which is similar to what has been observed for the distribution coefficient of aluminum between olivine and melt. Boron is, therefore, strongly incompatible during partial melting in the mantle. Using these distribution coefficients and assuming that MORB have been produced by 5-20% partial melting, the depleted mantle source of MORB is estimated to contain ˜0.05-0.3 ppm B. These values correspond to the lower limit for the mean boron content of chondrites (0.55 ± 0.3 ppm) but are in accordance with a simple budget of boron between mantle, crust, and seawater. In fact, a simple mass balance calculation, where all the boron hosted in the crust and in seawater is presumed to have been extracted from an upper mantle of chondritic original boron content, yields a boron content for the depleted upper mantle of ˜0.3 ppm at present. Because in situ boron concentration measurements under the ppm level at the ?m scale are now possible with the ion probe, and because of its strong partitioning in melts and possible partitioning in fluids, boron is a potentially very powerful geochemical tracer for the study of mantle processes such as basalt genesis or metasomatism.

Chaussidon, Marc; Libourel, Guy

1993-12-01

79

Quantum network teleportation for quantum information distribution and concentration  

NASA Astrophysics Data System (ADS)

We investigate the schemes of quantum network teleportation for quantum information distribution and concentration, which are essential in quantum cloud computation and the quantum internet. In those schemes, with the prior shared entanglement in the quantum network, the cloud can send simultaneously identical unknown quantum states to clients located in different places. Additionally, with the same entanglement resource, these clients can concentrate their states to the cloud to reconstruct the original state. The number of clients can be beyond the number of identical quantum states intentionally being sent; this quantum network teleportation can make sure that the quantum states' distribution is optimal in the sense that the fidelity achieves the upper bound. These schemes facilitate the quantum information distribution and concentration in quantum networks in the framework of quantum cloud computation. Potential applications in time synchronization and the photonic implementation of those schemes are discussed.

Zhang, Yong-Liang; Wang, Yi-Nan; Xiao, Xiang-Ru; Jing, Li; Mu, Liang-Zhu; Korepin, V. E.; Fan, Heng

2013-02-01

80

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

81

Frequency Distributions of Trace Metal Concentrations in Five Freshwater Fishes  

Microsoft Academic Search

Whole body concentrations of Cd, Cr, Cu, Fe, and Zn were determined for samples of chain pickerel (Esox niger), bluegill (Lepomis macrochirus), blueback herring (Alosa aestivalis), brook silverside (Labidesthes sicculus), and golden shiner (Notemigonus crysoleucas) from a 1,120-hectare impoundment near Aiken, South Carolina. Species differences in mean concentrations were found for all five elements. Frequency distributions of 23 species-element groupings

John P. Giesy Jr; James G. Wiener

1977-01-01

82

Frequency distributions of trace metal concentrations in five freshwater fishes  

Microsoft Academic Search

Whole body concentrations of Cd, Cr, Cu, Fe, and Zn were determined for samples of chain pickerel (Esox niger), bluegill (Lepomis macrochirus), blueback herring (Alosa aestivalis), brook silverside (Labidesthes sicculus), and golden shiner (Notemigonus crysoleucas) from a 1,120-hectare impoundment near Aiken, South Carolina. Species differences in mean concentrations were found for all five elements. Frequency distributions of 23 species-element groupings

JOHN P. GIESY; JAMES G. WIENER

1977-01-01

83

Rhombohedral crystal structure of compounds containing boron-rich icosahedra  

Microsoft Academic Search

The crystal structures of several icosahedral boron containing compounds have been refined using Mo K? intensity data. Though these compounds, ?-boron, boron carbide, boron phosphide and boron arsenide, differ chemically, all have the same basic rhombohedral structure. The structures consist of icosahedral units bonded together with direct B-B bonds as well as other linkage units. Similarities in electron distributions are

B. Morosin; A. W. Mullendore; D. Emin; G. A. Slack

1986-01-01

84

Rhombohedral crystal structure of compounds containing boron-rich icosahedra  

Microsoft Academic Search

The crystal structures of several icosahedral boron containing compounds have been refined using Mo Kalpha intensity data. Though these compounds, alpha-boron, boron carbide, boron phosphide and boron arsenide, differ chemically, all have the same basic rhombohedral structure. The structures consist of icosahedral units bonded together with direct B-B bonds as well as other linkage units. Similarities in electron distributions are

B. Morosin; A. W. Mullendore; D. Emin; G. A. Slack

1986-01-01

85

Kinetics of the formation of Fe 2B layers in gray cast iron: Effects of boron concentration and boride incubation time  

NASA Astrophysics Data System (ADS)

The growth kinetics of Fe 2B layers formed at the surface of gray cast iron were evaluated in this study. The pack-boriding process was applied to produce the Fe 2B phase at the material surface, and the variables included three temperatures (1173, 1223 and 1273 K) and four exposure times (2, 4, 6 and 8 h). Taking into account the growth fronts obtained at the surface of the material and the mass balance equation at the Fe 2B/substrate interface, the boron diffusion coefficient on the borided phase was estimated for the range of treatment temperatures. Likewise the parabolic growth constant, the instantaneous velocity of the Fe 2B/substrate interface, and the weight gain in the borided samples were established as a function of the parameters ?( t) and ?( C), which are related to the boride incubation time ( t0( T)) and boron concentration at the Fe 2B phase, respectively. Observation of the growth kinetics of the Fe 2B layers in gray cast irons suggest an optimum value of boron concentration that is in good agreement with the set of boriding experimental conditions used in this work.

Campos-Silva, I.; Ortiz-Domínguez, M.; Keddam, M.; López-Perrusquia, N.; Carmona-Vargas, A.; Elías-Espinosa, M.

2009-08-01

86

Surface Air Pollutant Concentration Frequency Distributions: Implications for Urban Modeling  

Microsoft Academic Search

With the development of ambient air quality standards (AAQS), the need arises to describe the characteristics of regional surface air-pollutant concentration frequency distributions. In the evaluation of land use plans, numerous agencies will be concerned with evaluating the effectiveness of emission zoning and\\/or control actions. On a regional basis, one means of performing this assessment lies in determining the changes

Joseph B. Knox; Rolf Lange

1974-01-01

87

CONCENTRATION DISTRIBUTIONS IN THE NEAR-WAKE OF A BUILDING  

EPA Science Inventory

A set of wind-tunnel data is presented which describes the concentration distributions resulting from diffusion of a passive tracer in the near-wake of a cubical building. ources were located near ground level both upstream and downstream of the building, and centered atop the bu...

88

3D concentration distributions of ion implants in amorphous solids  

Microsoft Academic Search

Spatial distributions of implanted ions have been derived from depth profiles of implants at varied incidence angle by applying tomographic techniques. To this end we have developed a new version of an algorithm known as simultaneous iterative reconstruction technique (SIRT), which covers the experimental concentration range of about three decades. In addition, the finite depth resolution of the nuclear reaction

R. Günzler; M. Weiser; S. Kalbitz

1992-01-01

89

Distribution of boron and its forms in young “Newhall” navel orange (Citrus sinensis Osb.) plants grafted on two rootstocks in response to deficient and excessive boron  

Microsoft Academic Search

Boron (B) deficiency is widespread and serious in navel orange orchards in southern Jiangxi in China and has been considered an important soil constraint to citrus yield and quality. It has been observed that there was great variation in responses to different B supply levels between “Newhall” navel orange grafted on citrange and trifoliate orange. The aim of this work

Liu Guidong; Jiang Cuncang; Wang Yunhua

2011-01-01

90

In-phantom two-dimensional thermal neutron distribution for intraoperative boron neutron capture therapy of brain tumours  

NASA Astrophysics Data System (ADS)

The aim of this study was to determine the in-phantom thermal neutron distribution derived from neutron beams for intraoperative boron neutron capture therapy (IOBNCT). Gold activation wires arranged in a cylindrical water phantom with (void-in-phantom) or without (standard phantom) a cylinder styrene form placed inside were irradiated by using the epithermal beam (ENB) and the mixed thermal-epithermal beam (TNB-1) at the Japan Research Reactor No 4. With ENB, we observed a flattened distribution of thermal neutron flux and a significantly enhanced thermal flux delivery at a depth compared with the results of using TNB-1. The thermal neutron distribution derived from both the ENB and TNB-1 was significantly improved in the void-in-phantom, and a double high dose area was formed lateral to the void. The flattened distribution in the circumference of the void was observed with the combination of ENB and the void-in-phantom. The measurement data suggest that the ENB may provide a clinical advantage in the form of an enhanced and flattened dose delivery to the marginal tissue of a post-operative cavity in which a residual and/or microscopically infiltrating tumour often occurs. The combination of the epithermal neutron beam and IOBNCT will improve the clinical results of BNCT for brain tumours.

Yamamoto, T.; Matsumura, A.; Yamamoto, K.; Kumada, H.; Shibata, Y.; Nose, T.

2002-07-01

91

Two-dimensional finite elements model for boron management in agroforestry sites.  

PubMed

Agroforesty systems, which are recommended as a management option to lower the shallow groundwater level and to reuse saline subsurface drainage waters from the tile-drained croplands in the drainage-impacted areas of Jan Joaquin Valley of California, have resulted in excessive boron buildup in the soil root zone. To assess the efficacy of the long-term impacts of soil boron buildup in agroforesty systems, a mathematical model was developed to simulate non-conservative boron transport. The developed dynamic two-dimensional finite element model simulates water flow and boron transport in saturated-unsaturated soil system, including boron sorption and boron uptake by root-water extraction processes. The simulation of two different observed field data sets by the developed model is satisfactory, with mean absolute error of 1.5 mg/L and relative error of 6.5%. Application of the model to three different soils shows that boron adsorption is higher in silt loam soil than that in sandy loam and clay loam soils. This result agrees with the laboratory experimental observations. The results of the sensitivity analysis indicate that boron uptake by root-water extraction process influences the boron concentration distribution along the root zone. Also, absorption coefficient and maximum adsorptive capacity of a soil for boron are found to be sensitive parameters. PMID:19184495

Tayfur, Gokmen; Tanji, Kenneth K; Baba, Alper

2010-01-01

92

Impact of carbon coimplantation on boron behavior in silicon: Carbon-boron coclustering and suppression of boron diffusion  

Microsoft Academic Search

Coimplantation of heterogeneous dopants in materials can be used to control the principal dopant distribution. We used atom probe tomography (APT) and secondary ion mass spectrometry (SIMS) to investigate the impact of coimplanted carbon on boron diffusion in silicon. After annealing, three-dimensional APT analysis of dopant distributions revealed the presence of carbon-boron coclusters around the projection range of boron. In

Y. Shimizu; H. Takamizawa; K. Inoue; T. Toyama; Y. Nagai; N. Okada; M. Kato; H. Uchida; F. Yano; T. Tsunomura; A. Nishida; T. Mogami

2011-01-01

93

Distribution of airborne radon-222 concentrations in U. S. homes  

Microsoft Academic Search

Apparently large exposures of the general public to the radioactive decay products of radon-222 present in indoor air have led to systematical appraisal of monitoring data from U.S. single-family homes; several ways of aggregating data were used that take into account differences in sample selection and season of measurements. The resulting distribution of annual-average radon-222 concentrations can be characterized by

A. V. Nero; M. B. Schwehr; W. W. Nazaroff; K. L. Revzan

1986-01-01

94

Effects assessment: boron compounds in the aquatic environment.  

PubMed

In previous studies, boron compounds were considered to be of comparatively low toxicity in the aquatic environment, with predicted no effect concentration (PNEC) values ranging around 1 mg B/L (expressed as boron equivalent). In the present study, we describe an evaluation of toxicity data for boron available for the aquatic environment by different methods. For substances with rich datasets, it is often possible to perform a species sensitivity distribution (SSD). The typical outcome of an SSD is the Hazardous Concentration 5% (HC5), the concentration at which 95% of all species are protected with a probability of 95%. The data set currently available on the toxic effects of boron compounds to aquatic organisms is comprehensive, but a careful evaluation of these data revealed that chronic data for aquatic insects and plants are missing. In the present study both the standard assessment factor approach as well as the SSD approach were applied. The standard approach led to a PNEC of 0.18 mg B/L (equivalent to 1.03 mg boric acid/L), while the SSD approach resulted in a PNEC of 0.34 mg B/L (equivalent to 1.94 mg boric acid/L). These evaluations indicate that boron compounds could be hazardous to aquatic organisms at concentrations close to the natural environmental background in some European regions. This suggests a possible high sensitivity of some ecosystems for anthropogenic input of boron compounds. Another concern is that the anthropogenic input of boron could lead to toxic effects in organisms adapted to low boron concentration. PMID:21055789

Schoderboeck, Lucia; Mühlegger, Simone; Losert, Annemarie; Gausterer, Christian; Hornek, Romana

2010-11-04

95

Distribution of indoor radon concentrations in Pennsylvania, 1990-2007  

USGS Publications Warehouse

Results from 548,507 indoor radon tests from a database compiled by the Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection, Radon Division, are evaluated in this report in an effort to determine areas where concentrations of radon are highest. Indoor radon concentrations were aggregated according to geologic unit and hydrogeologic setting for spatial analysis. Indoor radon concentrations greater than or equal to the U.S. Environmental Protection Agency (USEPA) action level of 4 picocuries per liter (pCi/L) were observed for 39 percent of the test results; the highest concentration was 1,866.4 pCi/L. When analyzed according to Pennsylvania’s geologic units, 93 of the 188 (49.5 percent) geologic units with indoor radon concentrations had median concentrations greater than the USEPA action level of 4 pCi/L; most of these geologic units are located in the eastern part of the State and include metamorphic rocks, limestones, sandstones, shales, and glacial deposits. When analyzed according to Pennsylvania’s hydrogeologic settings, 5 of the 20 (25 percent) settings had median indoor radon concentrations greater than the USEPA action level of 4 pCi/L; these settings are located mostly in the south-central part of the State. Median indoor radon concentrations aggregated according to geologic units and hydrogeologic settings are useful for drawing general conclusions about the occurrence of indoor radon in specific geologic units and hydrogeologic settings, but the associated data and maps have limitations. The aggregated indoor radon data have testing and spatial accuracy limitations due to lack of available information regarding testing conditions and the imprecision of geocoded test locations. In addition, the associated data describing geologic units and hydrogeologic settings have spatial and interpretation accuracy limitations, which are a result of using statewide data to define conditions at test locations and geologic data that represent a broad interpretation of geologic units across the State. As a result, indoor air radon concentration distributions are not proposed for use in predicting individual concentrations at specific sites nor for use as a decision-making tool for property owners to decide whether to test for indoor radon concentrations at specific property locations.

Gross, Eliza L.

2013-01-01

96

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

Miura, M.; Slatkin, D.N.

1995-10-03

97

3D concentration distributions of ion implants in amorphous solids  

NASA Astrophysics Data System (ADS)

Spatial distributions of implanted ions have been derived from depth profiles of implants at varied incidence angle by applying tomographic techniques. To this end we have developed a new version of an algorithm known as simultaneous iterative reconstruction technique (SIRT), which covers the experimental concentration range of about three decades. In addition, the finite depth resolution of the nuclear reaction analysis (NRA) is accounted for in our computer program. In this way, we have reconstructed the three-dimensional implantation distributions of 0.15 MeV 1H, 1.5 and 6 MeV 15N, and 4 MeV 30Si in amorphized Ge layers. The agreement with TRIM calculations is reasonable: 10% +/- 0.5% for the first and 10% +/- 5% for the second range moments. Consequences of the longitudinal and lateral tailing for ion beam applications to large scale integration problems are discussed.

Günzler, R.; Weiser, M.; Kalbitz, S.

1992-01-01

98

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

99

Measured variation in boron loads reaching European sewage treatment works  

Microsoft Academic Search

Per capita boron loads reaching 48 sewage treatment works (STWs) in The Netherlands, Germany, Italy, and the UK have been determined from monitoring data. These have been compared with the per capita input predicted from boron in detergents, as determined from detergent product sales data. The resulting distribution of the ratios of measured boron to boron predicted from consumer usage

K. K. Fox; G. Cassani; A. Facchi; F. R. Schröder; C. Poelloth; M. S. Holt

2002-01-01

100

Recombination Activity of Iron in Boron Doped Silicon  

NASA Astrophysics Data System (ADS)

The charge carrier lifetime in iron contaminated boron doped silicon wafers was determined by surface photovoltage, SPV, and microwave photoconductive decay, µPCD, techniques. Our results show that the charge carrier lifetime in boron doped silicon wafers depends on the boron concentration when the lifetime is limited by iron-boron pairs.

Yli-Koski, M.; Palokangas, M.; Sokolov, V.; Storgårds, J.; Väinölä, H.; Holmberg, H.; Sinkkonen, J.

101

Effect of boron and gadolinium concentration on the calculated neutron multiplication factor of U(3)O/sub 2/ fuel pins in optimum geometries  

SciTech Connect

The KENO-Va improved Monte Carlo criticality program is used to calculate the neutron multiplication factor for TMI-U2 fuel compositions in a variety of configurations and to display parametric regions giving rise to maximum reactivity contributions. The lattice pitch of UO/sub 2/ fuel pins producing a maximum k/sub eff/ is determined as a function of boron concentrations in the coolant for infinite and finite systems. The characteristics of U/sub 3/O/sub 8/-coolant mixtures of interest to modeling the rubble region of the core are presented. Several disrupted core configurations are calculated and comparisons made. The results should be useful to proposed defueling of the TMI-U2 reactor.

Thomas, J.T.

1984-10-01

102

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

Microsoft Academic Search

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

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

2011-01-01

103

Electron energy distributions, vibrational population distributions, and negative-ion concentrations in hydrogen discharges  

SciTech Connect

We consider the negative ion concentrations in hydrogen discharges caused by electron excitation and dissociative attachment processes. The principal formation and destruction processes are discussed for electron densities in the range 10/sup 8/ to 10/sup 13/ electrons cm/sup -3/. Expressions are developed for calculating the high energy portion of the electron energy distribution in the discharge; using these energy distributions the electron excitation rates are evaluated. At low densities, the vibrational distribution arises from singlet electronic excitations and triplet excitations through the /sup 3/..pi../sub u/ state, in equilibrium with wall de-excitation processes. At high densities singlet excitations predominate in equilibrium with atom-molecule de-excitation processes. Possibilities for negative ion generation in a two-chamber tandem system are discussed in which the vibrational excitation occurs in a high power, high electron temperature discharge, kT/sub e/ = 5 eV, and dissociative attachment occurs in a low temperature kT/sub e/ = 1 eV, plasma chamber.

Hiskes, J.R.; Karo, A.M.

1982-06-28

104

Boron alloy  

SciTech Connect

This paper describes a ferro-boron alloy produced in situ in a basic oxygen furnace, an induction furnace, or an electric furnace, or in combination with a mixing vessel. It comprises: 1.4% to 15% by weight boron; less than 0.002% by weight nitrogen; less than about 0.2% by weight carbon; less than about 0.01% by weight aluminum; and the balance iron with minute amounts of residuals.

Sussman, R.C.; Evans, L.G.

1990-06-26

105

Boron removal in RO seawater desalination  

Microsoft Academic Search

In the seawater desalination field, the WHO requires that boron concentration in drinking water be below 0.5 mg\\/l, and this requirement has affected SWRO process design because of the difficulty in achieving such a low boron concentration. In order to overcome this problem, anew SWRO membrane element with higher boron-rejecting performance was developed. This new SWRO membrane element exhibits excellent

Masahide Taniguchi; Yoshinari Fusaoka; Tsuyoshi Nishikawa; Masaru Kurihara

2004-01-01

106

Concentrations and Distribution of Heavy Metals in South Taihu Lake  

Microsoft Academic Search

The South Taihu Lake receive localized metal pollution from the factories nearby. The aim of this study was to find out the heavy metal accumulation in South Taihu Lake. Concentration of some heavy metals (Cu, Zn, Cr, Ni, Pb, Cd) were determined in sediments samples. Heavy metal levels were analyzed by ICP. Concentrations varied significantly from different sampling sites. The

Binghong Cheng; Yanling Qiu; Li Li; Zhiliang Zhu; Jiang Chen; Xiaohong Yang; Yuxin Yao

2010-01-01

107

Distribution and concentration of cadmium in human kidney  

SciTech Connect

The left kidneys from twenty males, aged 30 to 59, were examined. On an average, the cortex, medulla, and the remainder (renal pelvis and adjacent fatty tissue) constituted 65, 27, and 8 percent of the whole kidney weight, respectively. The mean cadmium concentrations were 18.4, 6.9,, and 3.2 ..mu..g Cd/g wet wt, respectively. The mean whole kidney cadmium concentration was 14.4 ..mu..g Cd/g wet wt. The kidney cortex concentration of cadmium can be approximated by multiplying the whole kidney concentration by a factor of 1.25, which is somewhat lower than the factor of 1.5 previously used. It may be necessary to recalculate previously reported estimates of critical concentrations for cadmium in kidney cortex based on neutron activation analyses in vivo of whole kidney.

Svartengren, M.; Elinder, C.G.; Friberg, L.; Lind, B.

1986-01-01

108

Analysis of concentration characteristics in ultrasonic atomization by droplet diameter distribution  

Microsoft Academic Search

The droplet diameter distribution and concentration characteristics in ultrasonic atomization were experimentally studied. The samples were aqueous solutions of methanol, ethanol and 1-propanol. The diameter distribution of atomized droplets showed the normal distribution, and the median diameter and standard deviation were expressed by means of the ultrasonic condition and the liquid properties. The concentration characteristic in ultrasonic atomization was analyzed

Keiji Yasuda; Yoshiyuki Bando; Soyoko Yamaguchi; Masaaki Nakamura; Akiyoshi Oda; Yasuhito Kawase

2005-01-01

109

Distribution and determinants of trihalomethane concentrations in indoor swimming pools  

PubMed Central

Objectives: For many decades chlorination has been used as a major disinfectant process for public drinking and swimming pool water in many countries. However, there has been rising concern over the possible link between disinfectant byproducts (DBPs) and adverse reproductive outcomes. The purpose of this study was to estimate the concentrations of trihalomethanes (THMs) in some indoor swimming pools in London and their variation within and between pools and any correlation with other factors. Methods: Water samples were collected from eight different indoor swimming pools in London. A total of 44 pool samples were collected and analysed for total organic content (TOC) and THMs. Water and air temperature were measured along with the pH during the collection of pool samples. The level of turbulence and the number of people in the pool at the time were also assessed. Results: The geometric mean concentration for all swimming pools of TOC was 5.8 mg/l, of total THMs (TTHMs) 132.4 µg/l, and for chloroform 113.3 µg/l. There was a clear positive linear correlation between the number of people in the swimming pool and concentrations of TTHMs and chloroform (r=0.7, p<0.01), and a good correlation between concentrations of TOC and TTHMs (r=0.5, p<0.05) and water temperature and concentrations of TTHMs (r=0.5, p<0.01). There was a larger variation in THMs within pools than between pools. Conclusion: Relatively high concentrations of THMs were found in London's indoor swimming pools. The levels correlated with the number of people in the pool, water temperature, and TOC. The variation in concentrations of THMs was greater within pools than between pools.

Chu, H; Nieuwenhuijsen, M

2002-01-01

110

Measurement of valence band structure in boron-zinc-oxide films by making use of ion beams  

SciTech Connect

Measurement of valence band structure in the boron-zinc oxide (BZO) films was developed using the secondary electron emission due to the Auger neutralization of ions. The energy distribution profile of the electrons emitted from boron-zinc-oxide films was measured and rescaled so that Auger self-convolution arose; thus, revealing the detailed structure of the valence band and suggesting that a high concentration of boron impurity in BZO films may enhance the transition of electrons and holes through the band gap from the valence to the conduction band in zinc oxide crystals; thereby improving the conductivity of the film.

Uhm, Han S.; Kwon, Gi C.; Choi, Eun H. [Department of Electrophysics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

2011-12-26

111

Structure and single-phase regime of boron carbides  

Microsoft Academic Search

The boron carbides are composed of twelve-atom icosahedral clusters which are linked by direct covalent bonds and through three-atom intericosahedral chains. The boron carbides are known to exist as a single phase with carbon concentrations from about 8 to about 20 at. %. This range of carbon concentrations is made possible by the substitution of boron and carbon atoms for

David Emin

1988-01-01

112

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

113

Access delay analysis of a distributed queue based ATM distributor-concentrator network  

Microsoft Academic Search

A distributed queue based ATM distributor-concentrator network may be used to provide a distributed cell multiplexing-demultiplexing function at a broadband user network interface (UNI). The distributor-concentrator network incorporates an asymmetric dual bus architecture and is based on the extended distributed queueing protocol. We analyse the access delay performance of extended distributed queueing in multiplexing the cell streams from delay-sensitive services.

Stephen G. Fischer; Guven Mercankosk

1995-01-01

114

Distribution of atmospheric methane concentration over different tectonic regions  

NASA Astrophysics Data System (ADS)

Measurements of atmospheric methane concentrations were made over the territories of Donetsk and Rostov Oblasts, Krasnodarsk Kray, the Uzbek, Kazakh, Turkmen, Azerbaijan, Georgian and Armenian republics. About 400 measurements were made at altitudes of 50 to 5,000 m. With transition from geosynclinal regions to ancient platforms there is a distinct decrease in methane concentration in the lower layers, attributable to different geological and tectonic conditions for the migration of methane into the atmosphere. Ancient platforms are tectonically quiet and subvertical migration processes are difficult. In geosynclinal regions there are favorable conditions for the subvertical migration of lithospheric gases due to the revival of existing and appearance of new fractures, dislocations and faults. The data demonstrated a definite influence of geotectonic conditions on formation of the atmospheric methane field. There is a distinct relationship between atmospheric methane concentration and the presence of petroleum- and gas-bearing structures beneath the Earth's surface. The geotectonic factor exerts an influence on methane concentration to the level 2,000 to 2,500 m. The presence of petroleum and gas in the underlying geological formations is reflected only in the lower layers of the atmosphere (up to 50 to 150 m).

Stadnik, Ye. V.; Sklyarenko, I. Ya.; Guliyev, I. S.; Feyzullayev, A. A.

1987-03-01

115

The mapping of natural boron in histological sections of mouse tissues by the use of neutron-capture radiography.  

PubMed

Neutron-capture radiography has been applied to the mapping of natural boron in mouse histological sections. The method is based on the fact that the stable isotope boron-10 has an extremely large cross-section for the thermal-neutron reaction 10B(n, alpha)7Li. The local tissue boron concentrations were evaluated from the corresponding track densities of the nuclear reaction using an equation derived from a theoretical model of the system. The adjustable parameters of this equation were determined in two separate calibration experiments using standardized samples prepared by the addition of known amounts of boron. Interference from other nuclides engaged in nuclear reactions with thermal neutrons was also estimated. In the present experimental conditions the natural boron lower detection limit was 0.03 p.p.m. (fresh weight), and the spatial resolution was of the order of a few micrometers. Boron concentrations in mouse serum and urine were close to 0.22 and 0.57 micrograms ml-1, respectively. In the solid mouse tissues--liver, heart, brain, muscle and spleen--the concentration was usually low, ranging from 0.12 to 0.16 p.p.m. (fresh weight). They were significantly higher in the kidney, especially in the papilla (6.2 p.p.m. fresh weight). Apart from the kidney papilla, where boron was particularly concentrated in wall tubules, the boron distribution in most tissues appeared to be practically homogeneous. Natural boron, and even more so its enriched stable isotope 10B, appear as good candidates for molecular labelling using non-radioactive tracers. PMID:1490868

Laurent-Pettersson, M; Delpech, B; Thellier, M

1992-12-01

116

Why boron?  

Microsoft Academic Search

It is now more than 80 years since boron was convincingly demonstrated to be essential for normal growth of higher plants. However, its biochemical role is not well understood at the moment. Several recent reviews propose that B is implicated in three main processes: keeping cell wall structure, maintaining membrane function, and supporting metabolic activities. However, in the absence of conclusive

Luis Bolaños; Krystyna Lukaszewski; Ildefonso Bonilla; Dale Blevins

2004-01-01

117

Nuclear microprobe analysis of the selective boron uptake obtained with BPA in brain tumour tissue  

NASA Astrophysics Data System (ADS)

The tumour selective ability of the boron compound boronophenylalanine (BPA), today used in Boron Neutron Capture Therapy in Sweden, has been investigated with the Lund Nuclear Microprobe. The tumour to tissue ratio of the boron concentration, as well as the location of boron within the cells, is critical for the efficiency of the therapy. It is desirable that the boron is accumulated as close as possible to the cell nucleus, since the alpha particles produced in the 10B(n,?)7Li reaction only have a range of about 10 microns, i.e. a cell diameter. The nuclear reaction 11B(p,?)2?, which has an especially high cross-section (300 mb) for 660 keV protons, has been used to analyse brain tissue from BPA-injected rats. Previous studies on other boron compounds have shown significant background problems when the alpha particles are detected in the backward direction. By a specially designed set-up, alpha particles in the forward and backward direction are detected simultaneously, and only the coincidences between the two directions are considered to be true boron events. In this way we could achieve excellent background suppression. The analysis shows that BPA indeed is tumour selective. Quantifications show a boron abundance of 150+/-20 ng/cm2 in normal tissue and 567+/-70 ng/cm2 in tumour tissue. If the rat is fed with l-dopa before the injection of BPA the uptake increases 3-4 times. The boron is homogeneously distributed in the cellular structure and no specific intracellular accumulation has been shown.

Wegdén, M.; Kristiansson, P.; Ceberg, C.; Munck Af Rosenschöld, P.; Auzelyte, V.; Elfman, M.; Malmqvist, K. G.; Nilsson, C.; Pallon, J.; Shariff, A.

2004-06-01

118

Boron translocation in coffee trees  

Microsoft Academic Search

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

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

2007-01-01

119

Boron uptake in normal melanocytes and melanoma cells and boron biodistribution study in mice bearing B16F10 melanoma for boron neutron capture therapy.  

PubMed

Information on (10)B distribution in normal tissues is crucial to any further development of boron neutron capture therapy (BNCT). The goal of this study was to investigate the in vitro and in vivo boron biodistribution in B16F10 murine melanoma and normal tissues as a model for human melanoma treatment by a simple and rapid colorimetric method, which was validated by HR-ICP-MS. The B16F10 melanoma cell line showed higher melanin content than human melanocytes, demonstrating a greater potential for boronophenylalanine uptake. The melanocytes showed a moderate viability decrease in the first few minutes after BNCT application, stabilizing after 75 min, whereas the B16F10 melanoma showed the greatest intracellular boron concentration at 150 min after application, indicating a different boron uptake of melanoma cells compared to normal melanocytes. Moreover, at this time, the increase in boron uptake in melanoma cells was approximately 1.6 times higher than that in normal melanocytes. The (10)B concentration in the blood of mice bearing B16F10 melanoma increased until 90 min after BNCT application and then decreased after 120 min, and remained low until the 240th minute. On the other hand, the (10)B concentration in tumors was increased from 90 min and maximal at 150 min after application, thus confirming the in vitro results. Therefore, the present in vitro and in vivo study of (10)B uptake in normal and tumor cells revealed important data that could enable BNCT to be possibly used as a treatment for melanoma, a chemoresistant cancer associated with high mortality. PMID:22491822

Faião-Flores, Fernanda; Coelho, Paulo Rogério Pinto; Arruda-Neto, João Dias Toledo; Camillo, Maria Aparecida Pires; Maria-Engler, Silvya Stuchi; Rici, Rose Eli Grassi; Sarkis, Jorge Eduardo Souza; Maria, Durvanei Augusto

2012-04-11

120

Demonstration of inter- and intracellular distribution of boron and gadolinium using micro-proton-induced X-ray emission (Micro-PIXE).  

PubMed

Micro-proton-induced X-ray emission (Micro-PIXE) was applied to determine inter- and intracellular distribution of boron (10B) and gadolinium (157Gd), the capture atoms used to kill tumor cells in neutron capture therapy (NCT). Cultured 9L gliosarcoma cells on Mylar film were exposed to sodium borocaptate (BSH) and gadobenate dimeglumine (Gd-BOPTA). To analyze the inter- and intracellular distribution of 10B and 157Gd in 9L gliosarcoma cells, the cells were irradiated using a proton beam of 1.7 or 3 MeV energy collimated to 1 microm diameter and emission X-ray was detected. The distribution of 10B and 157Gd in 9L gliosarcoma cells was then examined. In this study, we could directly analyze the inter- and intracellular distribution of 10B and 157Gd elements in 9L gliosarcoma cells directly using Micro-PIXE. This is the first report on the distribution of 10B employing a method to detect gamma-rays resulting from the nuclear reaction of 10B using particle-induced gamma-ray emission (PIGE). These results show that the distribution of 157Gd elements was correctly measured using micro-PIXE. 157Gd should have the same tendency as 10B in cultured 9L gliosarcoma cells and agree with the distribution in 9L gliosarcoma cells. Further investigation is necessary for a higher spatial resolution and optimization of the measurement time or improvement of the sampling method. In the future, it will be possible to employ this method to analyze the intracellular microdistribution of the capture element and in the development of new drugs for NCT. PMID:16898266

Endo, K; Yamamoto, T; Shibata, Y; Tsuboi, K; Matsumura, A; Kumada, H; Yamamoto, K; Sakai, T; Sato, T; Oikawa, M; Ohara, Y; Ishii, K

2006-01-01

121

Analysis of boron containing biological samples by ICP  

Microsoft Academic Search

An important aspect of boron neutron capture therapy (BNCT) is the determination of the biological distribution of the boron within an organism at some point in time after administration of a boron- containing species. Techniques include prompt gamma analysis, colorimetric techniques, and most recently, inductively coupled plasma atomic emission spectroscopy (ICP-AES) techniques. In this paper, an ICP technique was used

W. F. Bauer; D. A. Johnson; K. M. Messick; D. L. Miller; W. A. Propp; S. M. Steele

1988-01-01

122

Stable Continental North America: Concentrated or Distributed Strain?  

NASA Astrophysics Data System (ADS)

It has been a long-held paradigm that the high rate of Holocene seismic moment release in the New Madrid Seismic Zone is driven by a local stress concentration that raises strain rates above the low background rate that otherwise characterizes the stable continental region (SCR). Several plausible models have been proposed to account for a stress concentration, including post-glacial rebound (PGR), rapid river incision, and sinking of a dense mafic body. Independent observational evidence for a significantly elevated strain rate, apart from the inferred moment release rate, has, however, failed to materialize as GPS constraints have improved. I explore an alternate paradigm, that 1) the strain rate is relatively constant throughout SCR North America apart from the region where post-glacial rebound contributes a resolvable deformation signal, and 2) seismic activity is clustered on time scales of centuries, likely controlled by local earthquake-earthquake interactions that may be similar to those that play out on shorter time scales in interplate regions. A model along these lines has been suggested before, supported by qualitative arguments; using recent research results one can explore the model quantitatively. If, for example, one assumes a background SCR strain rate of 10-10yr-1 over a region bounded by 30 to 42N, and -95 to -75W, and seismogenic depth of 15 km, simple considerations predict a moment release rate of roughly 3x1024 dyne-cm/yr. This rate is sufficient to produce one Mw7.0 earthquake somewhere within the region every ~120 yr, or one Mw7.2 every 235 yr. One can compare this to the documented rate of moment release over the past millennium. There is compelling historical and/or paleoseismic evidence for three NMSZ sequences, each comparable to the 1811-1812 sequence, as well as three large earthquakes near Charleston, SC, since ?900 AD. Although other large events might have occurred, these NMSZ and Charleston events provide the dominant contribution to known moment release over the past 1000 years. Their magnitudes are not precisely constrained, but recent reconsideration of macroseismic data suggests a total moment release equivalent to Mw7-7.2 for the 1811-1812 sequence. A direct comparison of intensities further suggests that the 1886 Charleston earthquake was comparable in magnitude to the 16 Dec. 1811 New Madrid earthquake. We thus have direct evidence for 6 earthquakes with Mw close to 7 in the last 1100 years, an average rate of 183 yr. Although crude, these calculations suggest that a self-consistent model can be developed that assumes a low rate of background strain throughout SCR North America apart from the regions where strain associated with PGR is significant, with clustering over centuries to perhaps a few millennia, but significant migration possible on time scales of millennia to 10 ka. Within this framework, a low rate of observed moment release outside of Charleston and the NMSZ does not necessarily imply low long-term hazard, although the assumption of continued clustering is reasonable.

Hough, S. E.

2011-12-01

123

Effect of Particle Size Distribution and Concentration on Flow Behavior of Dense Slurries  

Microsoft Academic Search

The flow behavior of concentrated slurry depends on particle size distribution, shape, density, and concentration. The slurry flow behavior can change from Newtonian to non-Newtonian depending on the concentration, slurry composition, and content of fine and especially colloidal particles, which evoke a complex rheological behavior of the slurry. The present article deals with experimental investigation of the flow behavior and

Pavel Vlasak; Zdenek Chara

2011-01-01

124

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

125

Combination of boron and gadolinium compounds for neutron capture therapy. An in vitro study.  

PubMed

In neutron capture therapy, the therapeutic effect of the boron compound is based on alpha particles produced by the B(n, alpha) reaction while with the gadolinium compound the main radiation effect is from gamma rays derived from the Gd(n, gamma) reaction. The uptake and distribution within the tumor may be different among these compounds. Thus, the combination of the boron and gadolinium compounds may be beneficial for enhancing the radiation dose to the tumor. Chinese hamster fibroblast V79 cells were used. For the neutron targeting compounds, 10B (BSH) at 0, 5, 10, and 15 ppm, and 157Gd (Gd-BOPTA) at 0, 800, 1600, 2400, 3200, and 4800 ppm, were combined. The neutron irradiation was performed with thermal neutrons for 30 min. (neutron flux: 0.84 x 10(8) n/cm2/s in free air). The combination of the boron and gadolinium compounds showed an additive effect when the gadolinium concentration was lower than 1600 ppm. This additive effect decreased as a function of gadolinium concentration at 2400 ppm and resulted in no additive effect at more than 3200 ppm of gadolinium. In conclusion, the combination of the boron and gadolinium compounds can enhance the therapeutic effect with an optimum concentration ratio. When the gadolinium concentration is too high, it may weaken the boron neutron capture reaction due to the high cross-section of gadolinium compound against neutrons. PMID:15943038

Matsumura, A; Zhang, T; Nakai, K; Endo, K; Kumada, H; Yamamoto, T; Yoshida, F; Sakurai, Y; Yamamoto, K; Nose, T

2005-03-01

126

BORON CONCENTRATIONS IN MILK FROM MOTHERS OF FULL-TERM, BUT NOT PREMATURE, BREAST-FED INFANTS REMAIN STABLE DURING THE FIRST THREE MONTHS OF LACTATION WHILE COPPER, IRON, SELENIUM, AND ZINC CONCENTRATIONS...GESTATIONAL LENGTH  

Technology Transfer Automated Retrieval System (TEKTRAN)

To establish dietary intakes of boron of breastfed infants, we analyzed human milk from lactating mothers of premature (PRT, n = 10, 2500 g, 39-41 wk gestation) infants living in St John's, Newfoundland, Canada. Samples were col...

127

Characterization of electrodeposited elemental boron  

SciTech Connect

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

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

2008-07-15

128

Boron isotope fractionation during brucite deposition from artificial seawater  

Microsoft Academic Search

Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite. The results show that both concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (Kd) between deposited brucite and final seawater are controlled by pH

J. Xiao; Y. K. Xiao; C. Q. Liu; Z. D. Jin

2011-01-01

129

Boron isotope fractionation during brucite deposition from artificial seawater  

Microsoft Academic Search

Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite and the influence of it on Mg\\/Ca-SST proxy and delta11B-pH proxy. The results show that both the concentration of boron in deposited brucite ([B]d) and its boron partition

J. Xiao; Y. K. Xiao; C. Q. Liu; Z. D. Jin

2011-01-01

130

Model Studies Directed Toward the Boron Neutron-Capture Therapy of Cancer: Boron Delivery to Murine Tumors with Liposomes  

Microsoft Academic Search

The successful treatment of cancer by boron neutron-capture therapy (BNCT) requires the selective concentration of boron-10 within malignant tumors. The potential of liposomes to deliver boron-rich compounds to tumors has been assessed by the examination of the biodistribution of boron delivered by liposomes in tumor-bearing mice. Small unilamellar vesicles with mean diameters of 70 nm or less, composed of a

Kenneth Shelly; D. A. Feakes; M. Frederick Hawthorne; Paul G. Schmidt; Teresa A. Krisch; William F. Bauer

1992-01-01

131

On the Proportionality of Fine Mass Concentration and Extinction Coefficient for Bimodal Size Distributions.  

National Technical Information Service (NTIS)

For a bimodal size distribution of ambient aerosol, an upper limit in particle size can be chosen for the fine aerosol fraction so that the extinction coefficient for light scattering and absorption is directly proportional to the fine mass concentration,...

C. W. Lewis

1981-01-01

132

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

Microsoft Academic Search

Boron is an essential micronutrient for plants, and it is beneficial for animals. However, at high concentrations boron is toxic to cells although the mechanism of this toxicity is not known. Atr1 has recently been identified as a boron efflux pump whose expression is upregulated in response to boron treatment. Here, we found that the expression of ATR1 is associated

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

2011-01-01

133

Density separation of boron particles. Final report  

SciTech Connect

A density distribution much broader than expected was observed in lots of natural boron powder supplied by two different sources. The material in both lots was found to have a rhombohedral crystal structure, and the only other parameters which seemed to account for such a distribution were impurities within the crystal structure and varying isotopic ratios. A separation technique was established to isolate boron particles in narrow densty ranges. The isolated fractions were subsequently analyzed for B/sup 10/ and total boron content in an effort to determine whether selective isotopic enrichment and nonhomogeneous impurity distribution were the causes for the broad density distribution of the boron powders. It was found that although the B/sup 10/ content remained nearly constant around 18%, the total boron content varied from 37.5 to 98.7%. One of the lots also was found to contain an apparently high level of alpha rhombohedral boron which broadened the density distribution considerably. During this work, a capability for removing boron particles containing gross amounts of impurities and, thereby, improving the overall purity of the remaining material was developed. In addition, the separation technique used in this study apparently isolated particles with alpha and beta rhombohedral crystal structures, although the only supporting evidence is density data.

Smith, R.M.

1980-04-01

134

Nuclear reaction secondary particle dose distributions and dose enhancement by boron neutron capture in proton beam therapy evaluated using the LAHET code system  

NASA Astrophysics Data System (ADS)

The objective of this study was to use the LAHET Code System (LCS), which has recently been used in shielding calculations for proton therapy, to model the proton, neutron and photon dose and equivalent dose distributions created in tissue during proton beam cancer therapy. Proton beams used for therapy have shown distinct advantages over other therapeutic radiation treatments due to the rapid distal dose falloff in the region of the Bragg Peak. Nuclear reactions caused by the primary proton beam in beam modifying devices and patient tissues create secondary particles which contribute to the dose received by the patient inside and outside of the targeted region. The spatial distribution of the dose created by these secondary particles is an important consideration in the choice of beam modification methods and treatment volume planning, since a goal of radiation therapy is to minimize dose to normal tissue while maximizing dose to the tumor. The photon dose was found to be negligible in all target regions. The neutron dose and dose equivalent were found to be negligible in the tissue volume targeted for proton beam therapy, but contributed a majority of the dose outside of the treatment volume. Finally, LAHET was used to evaluate the utility of exploiting the secondary neutrons for supplemental boron neutron capture therapy during proton beam therapy. These results indicate that the additional useful dose due to BNCT is negligible.

Laky, Peter Gyula

135

Measurements of solid concentration and particle velocity distributions near the wall of a cyclone  

Microsoft Academic Search

The particle velocity and concentration distribution in the near-wall region of the cyclone were experimentally studied. A series of measurements were conducted with fiber optical probes (FOPs). It was found the radial solid concentration distribution is severe non-uniform and particles agglomerate as dense spiral bands near the wall, moving downwards with a certain interval. On the cross-section plane, from the

Shaohua Li; Hairui Yang; Hai Zhang; Shi Yang; Junfu Lu; Guangxi Yue

2009-01-01

136

Relationship of Serum Adiponectin and Leptin Concentrations with Body Fat Distribution in Humans  

Microsoft Academic Search

Objective: We investigated whether serum concentrations of adiponectin are determined by body fat distribution and compared the findings with leptin.Research Methods and Procedures: Serum concentrations of adiponectin and leptin were measured by radioimmunoassay (n = 394) and analyzed for correlation with sex, age, and body fat distribution, i.e., waist-to-hip ratio, waist and hip circumference, and subcutaneous adipose tissue area of

Harald Staiger; Otto Tschritter; Jürgen Machann; Claus Thamer; Andreas Fritsche; Elke Maerker; Fritz Schick; Hans-Ulrich Häring; Michael Stumvoll

2003-01-01

137

Cross-sections of 10B(?, p)13C nuclear reaction for boron analysis  

NASA Astrophysics Data System (ADS)

The 10B(?, p)13C nuclear reaction shows great potential in boron depth profiling due to its large cross-section and a narrow resonance in the MeV energy range. Unfortunately, the existing cross-section data on this reaction are too rough for depth profiling. We present an accurate measurement of the cross-section of the (?, p) reaction on 10B using a boron thin film on a Si substrate, high-resolution detection and careful analysis of the proton spectra. Angular distributions of the cross-section at the resonant energy Er=1512 keV are also presented. The sharp resonance at 1512 keV was used to measure the B depth distribution in a borophosphosilicate glass (BPSG) thin film. The boron concentration profiles are compared with SIMS measurement and are found in good agreement.

Chen, H.; Wang, X. M.; Shao, L.; Liu, J. R.; Yen, A. C.; Chu, Wei-Kan

2003-09-01

138

Boron-enhanced blistering and exfoliation in hydrogen-implanted SrTiO3  

NASA Astrophysics Data System (ADS)

The blistering behavior and the exfoliation of SrTiO3 single crystals were investigated using co-implantation with boron and hydrogen. In contrast to H-only-implantation, co-implantation of B+ with 1×1015 ions/cm2 at 80 kV and H+ with 5×1016 ions/cm2 at 40 kV caused a vigorous blistering and a complete exfoliation during the annealing process. A comparison of the blistering depth and the hydrogen distribution in the co-implanted samples revealed that the exfoliation did not occur in the regions of maximum hydrogen concentration or maximum hydrogen-related radiation damage. It occurred at the crossover of the boron distribution profile and hydrogen distribution profile. With the aid of an elastic recoil detection and the Rutherford backscattering spectroscopy in the channeling mode, the preimplanted boron was found to facilitate the long-range H movement into the B-implanted region, resulting in the chemical interaction between B and H. A bond analysis obtained from the Fourier transform infrared-attenuated total reflection spectroscopy showed that B-H interactions resulted in the formation of boron hydride. It is proposed that the boron hydride formation and decomposition upon annealing provided the needed gas pressure for the complete exfoliation of B+H co-implanted SrTiO3 crystals.

Lee, Jung-Kun; Averitt, Richard D.; Nastasi, Michael

2004-12-01

139

Development and Application of Watershed Regressions for Pesticides (WARP) for Estimating Atrazine Concentration Distributions in Streams  

USGS Publications Warehouse

Regression models were developed for predicting atrazine concentration distributions in rivers and streams, using the Watershed Regressions for Pesticides (WARP) methodology. Separate regression equations were derived for each of nine percentiles of the annual distribution of atrazine concentrations and for the annual time-weighted mean atrazine concentration. In addition, seasonal models were developed for two specific periods of the year--the high season, when the highest atrazine concentrations are expected in streams, and the low season, when concentrations are expected to be low or undetectable. Various nationally available watershed parameters were used as explanatory variables, including atrazine use intensity, soil characteristics, hydrologic parameters, climate and weather variables, land use, and agricultural management practices. Concentration data from 112 river and stream stations sampled as part of the U.S. Geological Survey's National Water-Quality Assessment and National Stream Quality Accounting Network Programs were used for computing the concentration percentiles and mean concentrations used as the response variables in regression models. Tobit regression methods, using maximum likelihood estimation, were used for developing the models because some of the concentration values used for the response variables were censored (reported as less than a detection threshold). Data from 26 stations not used for model development were used for model validation. The annual models accounted for 62 to 77 percent of the variability in concentrations among the 112 model development stations. Atrazine use intensity (the amount of atrazine used in the watershed divided by watershed area) was the most important explanatory variable in all models, but additional watershed parameters significantly increased the amount of variability explained by the models. Predicted concentrations from all 10 models were within a factor of 10 of the observed concentrations at most model development and model validation stations. Results for the two sets of seasonal models were similar. Concentration distributions derived from the seasonal-model predictions provided additional information compared to distributions derived from the annual models.

Larson, Steven J.; Crawford, Charles G.; Gilliom, Robert J.

2004-01-01

140

Boron-enhanced diffusion of boron from ultralow-energy boron implantation  

SciTech Connect

The authors have investigated the diffusion enhancement mechanism of BED (boron enhanced diffusion), wherein the boron diffusivity is enhanced three to four times over the equilibrium diffusivity at 1,050 C in the proximity of a silicon layer containing a high boron concentration. It is shown that BED is associated with the formation of a fine-grain polycrystalline silicon boride phase within an initially amorphous Si layer having a high B concentration. For 0.5 keV B{sup +}, the threshold implantation dose which leads to BED lies between 3 {times} 10{sup 14} and of 1 {times} 10{sup 15}/cm{sup {minus}2}. Formation of the shallowest possible junctions by 0.5 keV B{sup +} requires that the implant dose be kept lower than this threshold.

Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C. [Lucent Technologies, Murray Hill, NJ (United States). Bell Labs.; Haynes, T.E. [Oak Ridge National Lab., TN (United States). Solid State Div.; Erokhin, Y.E. [Eaton Corp., Beverly, MA (United States)

1998-05-03

141

Effect of bevacizumab treatment on p-boronophenylalanine distribution in murine tumor.  

PubMed

Previous studies have demonstrated that angiogenesis inhibitors can enhance tumor inhibitory effects of chemo- and radiotherapy via their action on tumor vessels. Here, we studied the effect of the angiogenesis inhibitor, bevacizumab (Avastin), on boron distribution in a murine tumor model. The human head and neck squamous cell carcinoma cell line was used for inoculation into mice. Boron-10 concentrations in tissues were measured by prompt ?-ray spectrometry (PGA). Hoechst 33342 perfusion and p-boronophenylalanine (BPA) distribution were determined by immunofluorescence staining. Our results revealed enhanced tumor blood perfusion and BPA accumulation in tumors after Avastin treatment, suggesting that combination of angiogenesis inhibition with treatment with boron compound administration may improve the efficacy of boron neutron capture therapy (BNCT) by modifying tumor vessels. In addition, our results also demonstrated the usefulness of immunofluorescence staining for investigating boron compound distribution at the cellular level. PMID:23135099

Liu, Yong; Suzuki, Minoru; Masunaga, Shin-Ichiro; Chen, Yi-Wei; Kashino, Genro; Tanaka, Hiroki; Sakurai, Yoshinori; Kirihata, Mitsunori; Ono, Koji

2012-11-06

142

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 700°C. 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

143

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

144

Seasonal variations of number size distributions and mass concentrations of atmospheric particles in Beijing  

NASA Astrophysics Data System (ADS)

Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities. Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.

Yu, Jianhua; Guinot, Benjamin; Yu, Tong; Wang, Xin; Liu, Wenqing

2005-06-01

145

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

146

The boron acceptor in diamond  

NASA Astrophysics Data System (ADS)

To date, the only dopant available for bulk diamond with good controllability is boron, which acts as an acceptor and can be incorporated in relatively high concentrations, allowing the design of devices for electronic applications. This paper summarizes data on doping procedures and on optical and electrical properties.

Thonke, Klaus

2003-03-01

147

Fabrication of vertically aligned diamond whiskers from highly boron-doped diamond by oxygen plasma etching.  

PubMed

Conductive diamond whiskers were fabricated by maskless oxygen plasma etching on highly boron-doped diamond substrates. The effects of the etching conditions and the boron concentration in diamond on the whisker morphology and overall substrate coverage were investigated. High boron-doping levels (greater than 8.4 × 10(20) cm(-3)) are crucial for the formation of the nanosized, densely packed whiskers with diameter of ca. 20 nm, length of ca. 200 nm, and density of ca. 3.8 × 10(10) cm(-2) under optimal oxygen plasma etching conditions (10 min at a chamber pressure of 20 Pa). Confocal Raman mapping and scanning electron microscopy illustrate that the boron distribution in the diamond surface region is consistent with the distribution of whisker sites. The boron dopant atoms in the diamond appear to lead to the initial fine column formation. This simple method could provide a facile, cost-effective means for the preparation of conductive nanostructured diamond materials for electrochemical applications as well as electron emission devices. PMID:21214209

Terashima, Chiaki; Arihara, Kazuki; Okazaki, Sohei; Shichi, Tetsuya; Tryk, Donald A; Shirafuji, Tatsuru; Saito, Nagahiro; Takai, Osamu; Fujishima, Akira

2011-01-07

148

Factors Controlling Droplet Concentration and Size Distribution in Clouds over Dominica  

NASA Astrophysics Data System (ADS)

Since precipitation in convective, tropical clouds, and the impact of these clouds on Earth's radiation budget, are dependent on the concentration and size distribution of the water droplets that make up the clouds, we are interested in understanding the factors controlling the droplet concentration and size distribution in these clouds. Previous studies from field campaigns have led to contradictory conclusions, with some research pointing to updraft velocity as the most influential factor, and other studies pointing to aerosol concentration. The 2011 Dominica Experiment (DOMEX) field campaign provides a wealth of data with which to study this problem, and to test existing models of droplet activation and growth; these data include aerosol and cloud droplet concentrations and size distributions, and wind speed measurements, from research flights above and upwind of the island of Dominica, as well as precipitation data from rain gauges installed on the island. Over 17 DOMEX research flights, cloud droplet concentrations averaged over flight legs above the island were positively correlated with aerosol concentrations from legs flown upwind of the island at 305 m altitude, while cloud droplet mean diameters were negatively correlated with oversea aerosol concentrations, supporting the idea that higher aerosol concentrations (if they are water soluble aerosols, such as sea salt) result in more droplets becoming activated and not growing as large. Meanwhile, average horizontal wind speeds in the oversea legs were negatively correlated with droplet concentrations in clouds over the island, and positively correlated with the mean diameter, the opposite of what would be expected if stronger convection accompanied the higher horizontal wind speeds. The horizontal wind speeds were also negatively correlated with the aerosol concentrations, especially at very low wind speeds, suggesting that the negative impact of wind speed on droplet concentration may have been due to a different aerosol regime that accompanied the lower wind speeds.

Russotto, R. D.; Storelvmo, T.; Smith, R. B.

2011-12-01

149

Concentration and distribution of tumor associated antigens TAG-72 and CEA in stomach cancer.  

PubMed

We measured the concentration and distribution of tumor associated antigens, TAG-72 and CEA, in stomach cancer by in vitro quantitative autoradiography (IV-QAR). Frozen sections of 33 specimens were incubated with varying concentrations of 125I-labeled CEA-79.1 and B72.3 antibodies specific for carcinoembryonic antigen (CEA) and tumor-associated glycoprotein-72 (TAG-72), respectively. Computer analysis of specific antibody binding gave maximal binding values which were equal to the concentrations of the antigen or epitope. TAG-72 was detected in 25 specimens, at a concentration ranging from 8.4 to 562.9 pmol/g. CEA was detected in 32 of the 33 specimens and its concentration ranged from 8.8 to 525.3 pmol/g. The distribution of TAG-72 by IV-QAR coincided with that of the tumor cells in 41.4% of the pathologic lesions. The distribution of CEA coincided with the tumor cells in 80.5% of pathologic lesions, nearly twice the TAG-72. The concentration of TAG-72 was significantly higher in mucinous adenocarcinoma and mucin containing adenocarcinomas than other types of adenocarcinomas. There was no significant difference in the concentration of CEA among the pathologic types of stomach cancer. In summary, stomach cancer exhibited wide variations in TAG-72 and CEA expression. CEA expression was more frequent and homogeneous than TAG-72. PMID:7779533

Chung, J K; Lee, M C; Chung, H K; Lim, S M; Jang, J J; Koh, C S

1995-02-01

150

Metal distribution in Al?CuyB105 (x=0-3.4, y=4.2-0) of the ?-rhombohedral boron structure  

NASA Astrophysics Data System (ADS)

Structures of Cu4.2B105 Al2.6Cu1.8B105, Al3.2Cu1.4B105, Al3.8Cu0.8B105, Al3.7Cu0.5B105, and Al3.4B105 (-120 °C) have been analyzed by the single-crystal X-ray diffractometry. They crystallize in the ?-rhombohedral boron structure. There is marked difference in the metal distributions between the Al-containing crystals and Cu4.2B105. In the Al-containing crystals, metal atoms occupy only A1 and D-holes, leaving E-hole empty. On the other hand, in the Cu4.2B105 crystals the Cu atoms occupy all three holes with the highest occupancy (60%) in the E-hole and the lowest occupancy (8%) in the A1-hole. In contrast, the occupancies of E and A1-holes in Al3.4B105 are 0 and 84%, respectively. The metal distributions in the crystals containing both Al and Cu are quite similar to that in Al3.4B105. All the Al-containing crystals show an extraordinary large and anisotropic temperature factor for the B(15) site, suggesting the presence of a disorder structure of this site. This is corroborated by analysis of low temperature X-ray diffraction data obtained using the Al3.4B105 crystal; the large temperature factor of B(15) did not decrease even when the crystal was cooled down to -120 °C.

Higashi, Iwami; Kobayashi, Masayoshi; Akagawa, Yuri; Kobayashi, Kimiko; Bernhard, Jonte

1991-07-01

151

Analysis of concentration characteristics in ultrasonic atomization by droplet diameter distribution.  

PubMed

The droplet diameter distribution and concentration characteristics in ultrasonic atomization were experimentally studied. The samples were aqueous solutions of methanol, ethanol and 1-propanol. The diameter distribution of atomized droplets showed the normal distribution, and the median diameter and standard deviation were expressed by means of the ultrasonic condition and the liquid properties. The concentration characteristic in ultrasonic atomization was analyzed by using the model of shell and core to the atomized droplet, where the former and latter consist of solute and solution, respectively. The value, which was surface solute amount in droplet multiplied by the molecular volume, increased with increasing solute molar fraction in bulk liquid and was independent of alcohol kinds. The rate of accompanying liquid and the solute molar fraction in accompanied liquid were estimated from the diameter distribution and the surface solute amount in droplet. PMID:15474950

Yasuda, Keiji; Bando, Yoshiyuki; Yamaguchi, Soyoko; Nakamura, Masaaki; Oda, Akiyoshi; Kawase, Yasuhito

2005-01-01

152

Radial distribution of the flow velocity, efficiency and concentration in a wide HPLC column  

Microsoft Academic Search

The use of optical fibers in a fluorescence-detection scheme permits the accurate determination of the radial distribution of the transit time, the column efficiency, and the analyte concentration at the exit of a chromatographic axial-compression column (50 mmID). The results obtained demonstrate that the column is not homogeneous, but suggest a nearly cylindrical distribution of the packing density. The average

Tivadar Farkas; Michael J. Sepaniak; Georges Guiochon

1997-01-01

153

Effect of weight loss and regional fat distribution on plasma leptin concentration in obese women  

Microsoft Academic Search

OBJECTIVES: To investigate how circulating leptin concentrations are related to regional fat distribution and whether moderate weight loss alters these relationships.DESIGN: A 6 month, clinical weight reduction trial with measurements before and after weight loss.SUBJECTS: 38 healthy, obese women (age: 44.3±9.9 y, BMI: 34.0±4.0 kg\\/m2).MEASUREMENTS: The following measurements were made. 1. indices of obesity and fat distribution: weight, body mass

P Rissanen; S Mäkimattila; T Vehmas; M Taavitsainen; A Rissanen

1999-01-01

154

Ecological risk assessment of a wetland exposed to boron  

SciTech Connect

A wetland located in the southeastern portion of the United States was the site of an investigation to determine the potential ecological risk of elevated boron concentrations to the flora and fauna living in the wetland. The conceptual model identified the vegetation as the primary receptor of concern, and thus the vegetation is the focus of this article. Samples of surface water, sediments, and selected vegetation were collected from the study wetland and several nearby reference sites and were analyzed for boron. Concentrations of boron in all three media exceeded reference site concentrations. Boron concentrations were highest near the suspected source but decreased almost to reference-site concentrations near the outer perimeter of the wetland. Some plants appeared stressed with yellowing and necrotic leaves; however, a correlation between tissue boron concentrations and the plant`s visual appearance was not apparent for all species studied. Modeling of the fate of boron indicated that the wetland has likely been at a steady state for many years and that boron concentrations were not expected to increase. It was concluded that no observable adverse ecological impacts to the vegetation could be attributed to boron, nor is it likely that the boron poses an unacceptable risk to the surrounding areas.

Powell, R.L.; Kimerle, R.A.; Coyle, G.T. [Monsanto Co., St. Louis, MO (United States). Environmental Sciences Center; Best, G.R. [Univ. of Florida, Gainesville, FL (United States)

1997-11-01

155

Boron removal from aqueous solution by direct contact membrane distillation.  

PubMed

The removal of boron from aqueous solution by direct contact membrane distillation (DCMD) was studied with self-prepared polyvinylidene fluoride (PVDF) hollow fiber membranes in the present work. The effect of pH, boron concentration, temperature and salt concentration of the feed solution on the boron rejection was investigated. The experimental results indicated that boron rejection was less dependent on the feed pH and salt concentration. DCMD process had high boron removal efficiency (>99.8%) and the permeate boron was below the maximum permissible level even at feed concentration as high as 750 mg/L. Although the permeate flux was enhanced exponentially with the feed temperature increasing, the influence of feed temperature on the boron rejection could be neglected. Finally, the natural groundwater sample containing 12.7 mg/L of boron was treated by DCMD process. The permeate boron kept below 20 microg/L whether the feed was acidified or not, but pre-acidification was helpful to maintain the permeate flux stability. All the experimental results indicated that DCMD could be efficiently used for boron removal from aqueous solution. PMID:20080336

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

2009-12-23

156

Concentration and distribution of tumor associated antigens TAG72 and CEA in stomach cancer  

Microsoft Academic Search

We measured the concentration and distribution of tumor associated antigens, TAG-72 and CEA, in stomach cancer byin vitro quantitative autoradiography (IV-QAR). Frozen sections of 33 specimens were incubated with varying concentrations of125I-labeled CEA-79.1 and B72.3 antibodies specific for carcinoembryonic antigen (CEA) and tumor-associated glycoprotein-72 (TAG-72),\\u000a respectively. Computer analysis of specific antibody binding gave maximal binding values which were equal to

June-Key Chung; Myung-Chul Lee; Hong-Keun Chung; Sang-Moo Litvt; Ja-June Jang; Chang-Soon Koh

1995-01-01

157

Plasma concentrations and organ distribution of thiopurines after oral application of azathioprine in mice  

Microsoft Academic Search

The plasma concentrations and tissue distribution of thiopurines were studied in mice after oral administration of 50 mg\\/kg azathioprine (AZA) using HPLC analysis. Peak concentrations of AZA and three other thiopurine metabolites in plasma [thiouric acid (TUA) >6-mercaptopurine (6-MP)>AZA>8-hydroxy-AZA] were observed as early as 10 min after drug application, thus indicating fast absorption and extensive metabolism of AZA, and were

Volkhard Kurowski; Heiko Iven

1991-01-01

158

Performance evaluation of two-dimensional compound elliptic lens concentrators using a yearly distributed insolation model  

Microsoft Academic Search

Optical performance of a two-dimensional compound elliptic lens (2D-CEL) for a photovoltaic static concentrator module has been studied as a function of half-acceptance angle using an yearly distributed insolation model. The maximum yearly averaged optical concentration ratio of 1.75 was obtained for global radiation when the 2D-CEL was installed at a tilt angle equal to the latitude of Tokyo (N35°).

K. Yoshioka; A. Suzuki; T. Saitoh

1999-01-01

159

Boron isotope fractionation during brucite deposition from artificial seawater  

NASA Astrophysics Data System (ADS)

Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite. The results show that both concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (Kd) between deposited brucite and final seawater are controlled by pH of the solution. The incorporation capacity of boron into brucite is much stronger than that into oxides and clay minerals. The isotopic compositions of boron in deposited brucite (?11Bd) are higher than those in the associated artificial seawater (?11Bisw) with fractionation factors ranging between 1.0177 and 1.0569, resulting from the preferential incorporation of B(OH)3 into brucite. Both boron adsorptions onto brucite and precipitation reaction of H3BO3 with brucite exist during deposition of brucite from artificial seawater. The simultaneous occurrence of both processes determines the boron concentration and isotopic fractionation of brucite. The isotopic fractionation behaviors and mechanisms of boron incorporated into brucite are different from those into carbonates. Furthermore, the isotopic compositions of boron in modern corals might be affected by the existence of brucite in madrepore and the preferential incorporation of B(OH)3 into brucite. An exploratory study for the influence of brucite on the boron isotopic composition in modern corals is justifiable.

Xiao, J.; Xiao, Y. K.; Liu, C. Q.; Jin, Z. D.

2011-03-01

160

Distribution of exposure concentrations and doses for constituents of environmental tobacco smoke.  

PubMed

The ultimate goal of the research reported in this series of three articles is to derive distributions of doses of selected environmental tobacco smoke (ETS)-related chemicals for nonsmoking workers. This analysis uses data from the 16-City Study collected with personal monitors over the course of one workday in workplaces where smoking occurred. In this article, we describe distributions of ETS chemical concentrations and the characteristics of those distributions (e.g., whether the distribution was log normal for a given constituent) for the workplace exposure. Next, we present population parameters relevant for estimating dose distributions and the methods used for estimating those dose distributions. Finally, we derive distributions of doses of selected ETS-related constituents obtained in the workplace for people in smoking work environments. Estimating dose distributions provided information beyond the usual point estimate of dose and showed that the preponderance of individuals exposed to ETS in the workplace were exposed at the low end of the dose distribution curve. The results of this analysis include estimations of hourly maxima and time-weighted average (TWA) doses of nicotine from workplace exposures to ETS (extrapolated from 1 day to 1 week) and doses derived from modeled lung burdens of ultraviolet-absorbing particulate matter (UVPM) and solanesol resulting from workplace exposures to ETS (extrapolated from 1 day to 1 year). PMID:10765411

LaKind, J S; Ginevan, M E; Naiman, D Q; James, A C; Jenkins, R A; Dourson, M L; Felter, S P; Graves, C G; Tardiff, R G

1999-06-01

161

A literature review of concentrations and size distributions of ambient airborne Pb-containing particulate matter  

NASA Astrophysics Data System (ADS)

The final 2008 lead (Pb) national ambient air quality standards (NAAQS) revision maintains Pb in total suspended particulate matter as the indicator. However, the final rule permits the use of low-volume PM10 (particulate matter sampled with a 50% cut-point of 10 ?m) Federal Reference Method (FRM) monitors in lieu of total suspended particulate (TSP) monitors for some non-source-oriented monitoring. PM10 FRM monitors are known to provide more reliable concentration measurements than TSP samplers because they are omni-directional samplers and so are not biased by wind conditions. However, by design they exclude the upper tail of the particle size distribution. Hence, each monitor produces uncertainties about measured concentrations of Pb-bearing PM. Uncertainties in reported Pb data are also related to spatiotemporal variation of the concentration and size distribution of Pb-bearing PM. Therefore, a comprehensive literature review was performed to summarize the current knowledge regarding the concentration and size distribution of Pb particles in the atmosphere. The objectives of this review were to compile data that could shed light on these uncertainties, to provide insights useful during future Pb NAAQS reviews, and to identify areas where more research is needed.Results of this review indicated that Pb size distribution data are relatively limited and often outdated. Thirty-nine articles were found to have sufficiently detailed information regarding airborne Pb concentrations, study location, sample collection methods, and analytical techniques; only 16 of those papers reported Pb concentration data for multiple size fractions. For the most part, U.S. and European studies from the last forty years illustrate that the largest mode of the size distribution of airborne particle-bound Pb has shifted to larger sizes while airborne Pb concentrations have decreased in urban areas. This shift occurred as tetraethyl Pb additives in gasoline were phased out and industrial emissions and resuspended road dust became more important sources of Pb. Several studies also suggested the occurrence of long-range transport of Pb-bearing PM from industrial emissions. Uncertainties associated with these studies include influence of wind speed and direction on captured concentrations and variability in analytical techniques used to quantify Pb concentrations on the reported size distributions.

Cho, Seung-Hyun; Richmond-Bryant, Jennifer; Thornburg, Jonathan; Portzer, Jeff; Vanderpool, Robert; Cavender, Kevin; Rice, Joann

2011-09-01

162

Application of wavelength scanning for measuring water vapour concentration by distributed laser diode  

NASA Astrophysics Data System (ADS)

A technique which takes advantage of distributed feedback laser diode (DFB-LD) wavelength scanning to measure water vapor concentration is presented. Concentration is gotten by peak absorption rate according to Beer-Lambert law and absorption coefficient of water vapor in HITRAN database. Theoretical work on the pressure affection to light intensity absorption rate has been done, a scheme is presented to cope with the affection of overlap of two adjacent lines, it takes advantage of the peak absorption difference between 1368.597nm and 1367.862 nm, and the difference value is used to calculate the water-vapor concentration.

Chang, Jun; Guangping, Lv; Zhou, Guoqing; Chen, Kun; Zhang, Yan; Wang, Zhongliang; Zhang, Shicong; Wang, Qiang; Song, Fujun

2011-09-01

163

Concentration and Size Distribution of Culturable Airborne Microorganisms in Outdoor Environments in Beijing, China  

Microsoft Academic Search

A one-year (from June 2003 to May 2004) study of airborne microbial concentration and size distribution was conducted systematically at three selected sampling sites in Beijing. Microbial samples were collected in triplicate for 3 min, 3 times per day, for 3 consecutive days of each month using FA-I sampler (imitated Andersen sampler, made by Applied Technical Institute of Liaoyang, China).

Zhiguo Fang; Zhiyun Ouyang; Hua Zheng; Xiaoke Wang

2008-01-01

164

Concentration and Distribution of Six Trace Metals in Northern Kentucky Soils  

Microsoft Academic Search

Concentration and distribution of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) were determined in 26 soil profiles (n = 78) of northern Kentucky in response to environmental concerns about increasing anthropogenic inputs in a fast-paced urbanizing area. The selected sites represent alluvial, glacial till or residual soils that have not received any biosolid- or

J. R. V. PILS; A. D. KARATHANASIS; T. G. MUELLER

2004-01-01

165

Distribution and concentration of total phenolics, condensed tannins, and nordihydroguaiaretic acid (NDGA) in creosotebush ( Larrea tridentata)  

Microsoft Academic Search

This paper focuses on the presence and distribution of secondary phenolic compounds found within creosotebush [Larrea tridentata (Sess. & Moc. ex DC.) Cov.]. Total phenolics, condensed tannins and nordihydroguaiaretic acid (NDGA) were measured in nine categories of tissue within creosotebush. Total phenolic and condensed tannin concentrations were determined using colorimetric methods while NDGA content was determined with high performance liquid

Paul W. Hyder; E. L. Fredrickson; Rick E. Estell; Mario Tellez; Robert P. Gibbens

2002-01-01

166

Occurrence and distribution of livestock concentration areas on intensively managed pastures  

Technology Transfer Automated Retrieval System (TEKTRAN)

Livestock frequently congregate at feeders, shades, or other sites on pastures creating point sources of nutrient runoff. Our objective was to determine the spatial distribution of soil nutrients in livestock concentration areas on pastures and quantify the relationships among the soil nutrient grad...

167

Prediction of Temperature and Concentration Distributions of Distillation Sieve Trays by CFD  

Microsoft Academic Search

A three-dimensional two-fluid computational fluid dynamics (CFD) model is developed to predict concentration and temperature distributions on sieve trays of distillation columns and good simulation results are obtained. The dispersed gas phase and continuous liquid phase are modeled in the Eulerian framework as two interpenetrating phases with interphase momentum, heat and mass transfer. Closure models are developed for interphase transfer

Mahmood-Reza Rahimi; Rahbar Rahimi; Farhad Shahraki; Morteza Zivdar

2006-01-01

168

Modeling concentration distribution and deformation during convection-enhanced drug delivery into brain tissue  

Microsoft Academic Search

Convection-enhanced drug delivery is a technique where a therapeutic agent is infused under positive pressure directly into the brain tissue. For predicting the final concentration distribution and optimizing infusion rate and catheter placement, numerical models can be of great help. However, despite advances in modeling this process, often the infused agent does not reach the targeted region prescribed in the

K. Støverud; M. Darcis; R. Helmig; S. M. Hassanizadeh

2012-01-01

169

Statistical distributions of trace metal concentrations in the northwestern Mediterranean atmospheric aerosol.  

PubMed

The concentrations of 11 crustal and anthropogenic trace metals (Li, Al, V, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) were measured from 2006 to 2008 in the atmospheric aerosol at a northwestern Mediterranean coast (station of Cap Ferrat, situated on the southeastern coast of France). Statistical models (lognormal, Weibull, and gamma) that best represented the trace metal distribution for this environment are described. The lognormal model was selected for the distributions of (in decreasing strength of the fit) Al, Co, Li, Zn, Mn, Cu, Pb, and Cd, i.e., metals that are introduced into the atmospheric aerosol by pulses inducing temporal variability in their concentrations. The gamma model was associated with Fe, i.e., metals that exhibit less inter-annual variability than the former trace metals. The third mode (Weibull) represented the distribution of the concentrations of V and Ni. The statistical approach presented in this study contributed to better define and constrain the distribution of the 11 trace metals of the atmospheric aerosol from the northwestern Mediterranean coast. In a close future, knowledge of these statistical distributions will allow using convolution models to separate their natural and anthropogenic contributions, therefore increasing our ability to study anthropogenic emissions of trace metals and their impact on the environment. PMID:23685929

Robin, Thomas; Guidi, Lionel; Dufour, Aurélie; Migon, Christophe

2013-05-18

170

Prediction of In-Phantom Dose Distribution Using In-Air Neutron Beam Characteristics for Boron Neutron Capture Synovectomy  

SciTech Connect

A monoenergetic neutron beam simulation study was carried out to determine the optimal neutron energy range for treatment of rheumatoid arthritis using radiation synovectomy. The goal of the treatment is the ablation of diseased synovial membranes in joints such as knees and fingers. This study focuses on human knee joints. Two figures of merit are used to measure the neutron beam quality, the ratio of the synovium-absorbed dose to the skin-absorbed dose, and the ratio of the synovium-absorbed dose to the bone-absorbed dose. It was found that (a) thermal neutron beams are optimal for treatment and that (b) similar absorbed dose rates and therapeutic ratios are obtained with monodirectional and isotropic neutron beams. Computation of the dose distribution in a human knee requires the simulation of particle transport from the neutron source to the knee phantom through the moderator. A method was developed to predict the dose distribution in a knee phantom from any neutron and photon beam spectra incident on the knee. This method was revealed to be reasonably accurate and enabled one to reduce the particle transport simulation time by a factor of 10 by modeling the moderator only.

Verbeke, Jerome M. [University of California, Berkeley (United States); Chen, Allen S. [University of California, Berkeley (United States); Vujic, Jasmina L. [University of California, Berkeley (United States); Leung, Ka-Ngo [Lawrence Berkeley National Laboratory (United States)

2000-08-15

171

Estimating properties of concentrated parallel electric fields from electron velocity distributions  

NASA Astrophysics Data System (ADS)

Information about the magnitude of the field-aligned potential drop along auroral field lines is usually derived from the velocity distribution of the particles. So far the electron distribution functions have been used systematically only to derive the total potential drop above the satellite, by setting it equal to the peak energy of the electrons. When the electrons are accelerated by a concentrated electric field, their velocity distribution will have features different from those produced by a weak, spread-out, electric field. Quantifying these features, we obtain a method that can provide details about the strength and thickness of a concentrated electric field layer when it is located not too far above the satellite. The method is checked and proved to work satisfactory on simulated and measured data.

Vedin, Jörgen; Rönnmark, Kjell; Bunescu, Costel; Marghitu, Octav

2007-08-01

172

Distribution of exposure concentrations and doses for constituents of environmental tobacco smoke  

SciTech Connect

The ultimate goal of the research reported in this series of three articles is to derive distributions of doses of selected environmental tobacco smoke (ETS)-related chemicals for nonsmoking workers. This analysis uses data from the 16-City Study collected with personal monitors over the course of one workday in workplaces where smoking occurred. In this article, the authors describe distributions of ETS chemical concentrations and the characteristics of those distributions for the workplace exposure. Next, they present population parameters relevant for estimating dose distributions and the methods used for estimating those dose distributions. Finally, they derive distributions of doses of selected ETS-related constituents obtained in the workplace for people in smoking work environments. Estimating dose distributions provided information beyond the usual point estimate of dose and showed that the preponderance of individuals exposed to ETS in the workplace were exposed at the low end of the dose distribution curve. The results of this analysis include estimations of hourly maxima and time-weighted average (TWA) doses of nicotine from workplace exposures to ETS and doses derived from modeled lung burdens of ultraviolet-absorbing particulate matter (UVPM) and solanesol resulting from workplace exposures to ETS (extrapolated from 1 day to 1 year).

LaKind, J.S. [LaKind Associates (United States); Ginevan, M.E. [M.E. Ginevan and Associates (United States); Naiman, D.Q. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Mathematical Sciences; James, A.C. [A.C. James and Associates (United States); Jenkins, R.A. [Oak Ridge National Lab., TN (United States); Dourson, M.L.; Felter, S.P. [TERA (United States); Graves, C.G.; Tardiff, R.G. [Sapphire Group, Inc., Bethesda, MD (United States)

1999-06-01

173

Boron removal from seawater reverse osmosis permeate utilizing selective ion exchange resin  

Microsoft Academic Search

A minimum of boron in irrigation water is required for certain metabolic activities, but if its concentration is only slightly higher, plant growth will exhibit effects of boron poisoning, which are yellowish spots on the leaves and fruits, accelerated decay and ultimately plant expiration. Seawater in general contains relatively high concentration of boron: 4 to 5 ppm. The Red Sea

Nissim Nadav

1999-01-01

174

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

175

The effect of dissolved oxygen concentration on the structure, size and size distribution of activated sludge flocs  

Microsoft Academic Search

The variations in activated sludge floc structure, size and size distribution were studied for different dissolved oxygen (DO) concentrations in pilot scale completely mixed reactors. The size distribution by volume for flocs larger than about 10?m fitted well to log–normal distribution functions. No clear relationship between DO concentration and average floc diameter could be found; there was only a trend

Britt-Marie Wilén; Peter Balmér

1999-01-01

176

Distribution of sulfhydryl boranes in mice and rats  

SciTech Connect

The distribution of boron in mice bearing transplanted Harding-Passey melanomas after rapid and slow administration of monomer were studied. Thin layer chromatographic analysis of the corresponding infusion solution revealed a slow-moving principal band that was later shown to correspond to Na/sub 4/B/sub 24/H/sub 22/S/sub 2/, the dimer of Na/sub 2/B/sub 12/H/sub 11/SH. It was found that while monomer and chemically synthesized dimer yielded similar boron concentrations when they were given rapidly intraperitoneally to mice, the dimer yielded higher boron concentrations in mouse melanoma and higher melanoma-blood boron concentration when each was infused slowly intraperitoneally for 8 to 9 days. Studies have been started on the uptake of dimer into an intracerebrally implanted rat glioma. Boron levels in the rat glioma and in the mouse melanoma from slow intraperitoneal infusion of proportionately comparable amounts of dimer, are similar. However, after these slow infusions boron levels in rat blood are about as high as boron levels in rat brain tumor. 6 refs., 1 fig., 4 tabs.

Slatkin, D.N.; Micca, P.L.; Laster, B.H.; Fairchild, R.G.

1986-01-01

177

[Interpretation of spatial distribution pattern for dissolved inorganic nitrogen concentration in coastal estuary using hyperspectral data].  

PubMed

Choosing dissolved inorganic nitrogen (DIN) as one of the representative nutritional salt monitoring indexes, a hyperspectral remotely sensed inversion model was built and applied to quantitatively retrieve water quality parameters with its spatial distribution patterns in coastal estuary with high suspended sediment concentration (SSC). It was found that when SSC was larger than 0.1 kg/m3, DIN concentration had a notable inverse correlation with SSC and the correlation coefficient R2 reached 0.617. Based on this conclusion, firstly the in-situ observed water surface remote sensing reflectance was resampled according to the spectral response characters of Hyperion sensor. And then, statistical correlation analysis between reflectance and DIN concentration was carried out. The results showed that band reflectance of R804 and R630 representing the second and first reflectance peak of water spectrum curve were sensitive to the variation of DIN concentration. And then, a pseudo remotely sensed sand parameter index R804 x R630/(R804 - R630) was calculated for the construction of the nonlinear DIN quantitative reversion model. Correlation coefficient R2 between observed and simulated DIN concentrations for 29 calibrating samples and 10 validating samples were 0.746 and 0.67, while their mean absolute errors reached 109.07 and 147.58 microg/L, respectively. The model was then applied on Hyperion hyperspectral image to get the spatial distribution character of DIN concentration in Sheyanghe river estuary and the DIN concentration was between 52 to 513 microg/L. Results indicated that in coastal estuary which was dominated by suspended sediments, the diffusive trends of DIN concentration reversed by remote sensing techniques had an intimate relationship with motions of tidal current and transportation attributes of SSC. As the hydrodynamic conditions were unclear, hyperspectral remote sensing technique was an effective technical way for dynamic survey of DIN concentration. PMID:20698253

Zhang, Dong; Xu, Yong; Zhang, Ying; Li, Huan

2010-06-01

178

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

PubMed Central

Boron is a micronutrient in plants and animals, but its specific roles in cellular processes are not known. To understand boron transport and functions, we screened a yeast genomic DNA library for genes that confer resistance to the element in Saccharomyces cerevisiae. Thirty boron-resistant transformants were isolated, and they all contained the ATR1 (YML116w) gene. Atr1 is a multidrug resistance transport protein belonging to the major facilitator superfamily. C-terminal green fluorescent protein-tagged Atr1 localized to the cell membrane and vacuole, and ATR1 gene expression was upregulated by boron and several stress conditions. We found that atr1? mutants were highly sensitive to boron treatment, whereas cells overexpressing ATR1 were boron resistant. In addition, atr1? cells accumulated boron, whereas ATR1-overexpressing cells had low intracellular levels of the element. Furthermore, atr1? cells showed stronger boron-dependent phenotypes than mutants deficient in genes previously reported to be implicated in boron metabolism. ATR1 is widely distributed in bacteria, archaea, and lower eukaryotes. Our data suggest that Atr1 functions as a boron efflux pump and is required for boron tolerance.

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

2009-01-01

179

Flux density distribution in the focal region of a solar concentrator system  

SciTech Connect

In high temperature solar energy applications highly concentration optical systems, such as, e.g., parabolic dishes, achieve typical tradition flux densities {gt}2 MW/M{sup 2}. In order to investigate thermo and photochemical reactions at temperatures {gt}1500 K and radiation flux densities {gt}2 MW/m{sup 2} a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is a prefocusing glass heliostat with a focal length of 100 m. The second stage is an highly concentrating parabolic dish with a focal length of 1.93 m. To design experiments to be carried out in the focal region of the parabolic dish, the radiation flux as well as its density distribution have to be known. This distribution is usually measured by radiometric methods. However, these methods are generally rather troublesome because of the high temperatures involved. In this paper the authors present a simple method to estimate the characteristic features of the radiation flux density distribution in the focal region of the concentrator system.

Schubnell, M.; Keller, J.; Imhof, A. (Paul Scherrer Inst., CH-5232 Villigen-PSI (CH))

1991-05-01

180

Boron removal from seawater by electro-chemical treatment as part of water desalination  

Microsoft Academic Search

Significant decrease of boron concentration during seawater desalination is one of the more difficult, consuming and expensive tasks. Average boron concentration in the Mediterranean Sea is 4 mg\\/l, and due to heavy use of wastewater in irrigation the Israeli Water Authority (Ministry of Health) demands boron reduction to 0.4 mg\\/l maximum. The current boron removal procedure is based on two-pass

Einan Ofir; Asher Brenner; Karren Muuler; Vitaly Gitis

2011-01-01

181

Path concentration distribution of toluene using remote sensing FTIR and one-dimensional reconstruction method.  

PubMed

A one-dimensional mapping technique coupled with Open-Path remote sensing FTIR was presented in this article. This technique was applied to one of the air toxic volatile organic compounds (VOCs)-toluene. The Path Integrated Concentrations (PICs) of toluene in different path lengths along one beam path were fitted by polynomial fitting method with degrees from 3 to 7. The 6th degree polynomial fitting showed the best fitting result. Moreover, the methods of reconstructing path concentration distribution along the beam path by applying a Gaussian model and the derivative of 6th degree polynomial fitting function were established in this article. The reconstructed concentrations of toluene along the beam path by the two methods were experimentally close. Results showed that the concentration peaks were at 1.05 and 2.40 m from the instrument by applying the Gaussian model with the maximum concentration of 0.85 and 3.19 ppm, and at 0.99 and 2.49 m from the instrument with the maximum concentration of 0.78 and 2.80 ppm by applying the 6th polynomial fitting function. It was obvious that the reconstruction results by these two methods were very close. This approach could be appreciated for its fast calculation, exact peak location orientation and concentration flow tendency mapping. In can be concluded that this method can provide the path concentration distributions of much more releasing gases in a briefly and intuitionistic way. The remote sensing FTIR coupled with these mathematical reconstruction techniques can be applied to the real world environmental and industrial hygiene monitoring, thus works as an alert system for the VOCs pollution. PMID:15663309

Li, Yan; Xu, Houqian; Xue, Rui; Wang, Xiaofei; Ren, Yibo; Wang, Lianjun; Wang, Junde

2005-01-01

182

Analysis of elemental concentration censored distributions in breast malignant and breast benign neoplasm tissues  

NASA Astrophysics Data System (ADS)

The total reflection X-ray fluorescence method was applied to study the trace element concentrations in human breast malignant and breast benign neoplasm tissues taken from the women who were patients of Holycross Cancer Centre in Kielce (Poland). These investigations were mainly focused on the development of new possibilities of cancer diagnosis and therapy monitoring. This systematic comparative study was based on relatively large (˜ 100) population studied, namely 26 samples of breast malignant and 68 samples of breast benign neoplasm tissues. The concentrations, being in the range from a few ppb to 0.1%, were determined for thirteen elements (from P to Pb). The results were carefully analysed to investigate the concentration distribution of trace elements in the studied samples. The measurements of concentration of trace elements by total reflection X-ray fluorescence were limited, however, by the detection limit of the method. It was observed that for more than 50% of elements determined, the concentrations were not measured in all samples. These incomplete measurements were treated within the statistical concept called left-random censoring and for the estimation of the mean value and median of censored concentration distributions, the Kaplan Meier estimator was used. For comparison of concentrations in two populations, the log-rank test was applied, which allows to compare the censored total reflection X-ray fluorescence data. Found statistically significant differences are discussed in more details. It is noted that described data analysis procedures should be the standard tool to analyze the censored concentrations of trace elements analysed by X-ray fluorescence methods.

Kubala-Kuku?, A.; Bana?, D.; Braziewicz, J.; Gó?d?, S.; Majewska, U.; Pajek, M.

2007-07-01

183

Model of boron diffusion from gas phase in silicon carbide  

SciTech Connect

Boron diffusion from the gas phase in silicon carbide is described on the basis of a two-component model. 'Shallow' boron, i.e., boron at silicon sites, is a slow component with a high surface concentration. Its diffusivity is proportional to the concentration of positively charged intrinsic point defects, which are presumably interstitial silicon atoms. 'Deep' boron, i.e., impurity-defect pairs of boron-carbon vacancy, is a fast component with lower surface concentration. The ratio between the surface concentrations of the components depends on the pressure of silicon or carbon vapors in the gas phase. The diffusion and interaction of components are described by the set of diffusion-reaction equations. The diffusion retardation observed on the concentration-profile tail is related to the capture of impurity-defect pairs and excess vacancies by traps of background impurities and defects.

Aleksandrov, O. V., E-mail: Aleksandr_ov@mail.ru [St. Petersburg State Electrotechnical University, 'LETI' (Russian Federation); Mokhov, E. N., E-mail: Mokhov@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation)

2011-06-15

184

Spatial distribution of lead concentrations in urban surface soils of New Orleans, Louisiana USA.  

PubMed

Immediately following hurricane Katrina concern was raised over the environmental impact of floodwaters on the city of New Orleans, especially in regard to human health. Several studies were conducted to determine the actual contaminant distribution throughout the city and surrounding wetlands by analyzing soil, sediment, and water for a variety of contaminants including organics, inorganics, and biologics. Preliminary investigations by The Institute of Environmental and Human Health at Texas Tech University concluded that soils and sediments contained pesticides, semi-volatiles, and metals, specifically arsenic, iron, and lead, at concentrations that could pose a significant risk to human health. Additional studies on New Orleans floodwaters revealed similar constituents as well as compounds commonly found in gasoline. More recently, it has been revealed that lead (Pb), arsenic, and vanadium are found intermittently throughout the city at concentrations greater than the human health soil screening levels (HHSSLs) of 400, 22 (non-cancer endpoint) and 390 ?g/g, respectively. Of these, Pb appears to present the greatest exposure hazard to humans as a result of its extensive distribution in city soils. In this study, we spatially evaluated Pb concentrations across greater New Orleans surface soils. We established 128 sampling sites throughout New Orleans at approximately half-mile intervals. A soil sample was collected at each site and analyzed for Pb by ICP-AES. Soils from 19 (15%) of the sites had Pb concentrations exceeding the HHSSL threshold of 400 ?g/g. It was determined that the highest concentrations of Pb were found in the south and west portions of the city. Pb concentrations found throughout New Orleans in this study were then incorporated into a geographic information system to create a spatial distribution model that can be further used to predict Pb exposure to humans in the city. PMID:20054703

Abel, Michael T; Suedel, Burton; Presley, Steven M; Rainwater, Thomas R; Austin, Galen P; Cox, Stephen B; McDaniel, Les N; Rigdon, Richard; Goebel, Timothy; Zartman, Richard; Leftwich, Blair D; Anderson, Todd A; Kendall, Ronald J; Cobb, George P

2010-01-07

185

Effect of dietary boron on the aging process.  

PubMed Central

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

Massie, H R

1994-01-01

186

The toxicity of waterborne boron to Daphnia magna and Chironomus decorus and the effects of water hardness and sulfate on boron toxicity  

Microsoft Academic Search

The concentrations of many elements, including boron, are increasing in aquatic ecosystems due to anthropogenic activities. Laboratory studies were undertaken to evaluate the toxicity of waterborne boron to two key fresh water macroinvertebrates and to evaluate the effects of water hardness and sulfate on boron toxicity. Acute toxicity evaluations of waterborne sodium tetraborate resulted in 48 h. LC50 values of

Kurt J. Maier; Allen W. Knight

1991-01-01

187

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

188

Concentration and vertical distribution of plutonium and americium in Italian mosses and lichens  

Microsoft Academic Search

The plutonium and americium concentration and vertical distribution in some Italian mosses and lichens have been determined. The239,240Pu,238Pu and241Am concentration ranges in tree trunk lichens 0.83–1.87, 0.052–0.154 and 0.180–0.770 Bq\\/kg, respectively. The corresponding values in tree mosses are higher and more scattered ranging from 0.321 to 4.96, from 0.029 to 0.171 and from 0.200 to 1.93 Bq\\/kg. The mean238Pu\\/239,240Pu and241Am\\/239,240Pu

G. Jia; D. Desideri; F. Guerra; M. A. Meli; C. Testa

1997-01-01

189

The level and distribution of ²²?Rn concentration in soil-gas in Guangdong Province, China.  

PubMed

In order to understand the level and distribution of (220)Rn concentrations in soil-gas in the high-radiation-background area, an (220)Rn survey was carried out for the first time using a RAD7 portable radon monitor at 67 locations covering a total area of 1800 km(2) in the South of China. (220)Rn concentrations were significantly different from that in the surface areas covered by the weathered granite of Yanshan Period or Quaternary sediments. The (220)Rn concentrations varied between 6.65 and 461 kBq m(-3) and the averages were 294.42 ± 81.36 and 23.30 ± 25.84 kBq m(-3) for weathered granite products and sediments, respectively. A high positive correlation between (220)Rn concentrations and (232)Th activity concentrations was found. (220)Rn concentrations had no statistically significant variations from depths of 20-140 cm with an interval of 20 cm. It is worth paying attention to the problem of such a high soil (220)Rn concentration in Zhuhai City and Zhongshan City. PMID:22923249

Wang, N; Peng, A; Xiao, L; Chu, X; Yin, Y; Qin, C; Zheng, L

2012-08-23

190

Distribution of the concentration of heavy metals associated with the sediment particles accumulated on road surfaces.  

PubMed

The heavy metal pollution caused by road run-off water constitutes a problem in urban areas. The metallic load associated with road sediment must be determined in order to study its impact in drainage systems and receiving waters, and to perfect the design of prevention systems. This paper presents data regarding the sediment collected on road surfaces in the city of Torrelavega (northern Spain) during a period of 65 days (132 samples). Two sample types were collected: vacuum-dried samples and those swept up following vacuuming. The sediment loading (g m(-2)), particle size distribution (63-2800 microm) and heavy metal concentrations were determined. The data showed that the concentration of heavy metals tends to increase with the reduction in the particle diameter (exponential tendency). The concentrations ofPb, Zn, Cu, Cr, Ni, Cd, Fe, Mn and Co in the size fraction <63 microm were 350, 630, 124, 57, 56, 38, 3231, 374 and 51 mg kg(-1), respectively (average traffic density: 3800 vehicles day(-1)). By increasing the residence time of the sediment, the concentration increases, whereas the ratio of the concentration between the different size fractions decreases. The concentration across the road diminishes when the distance between the roadway and the sampling siteincreases; when the distance increases, the ratio between size fractions for heavy metal concentrations increases. Finally, the main sources of heavy metals are the particles detached by braking (brake pads) and tyre wear (rubber), and are associated with particle sizes <125 microm. PMID:21882553

Zafra, C A; Temprano, J; Tejero, I

2011-07-01

191

Concentration and distribution of sixty-one elements in coals from DPR Korea  

Microsoft Academic Search

Fifty coal samples (28 anthracite and 22 lignites) were collected from both main and small coal mines in DPR Korea prioritized by resource distribution and coal production. The concentrations of 61 elements in 50 coal samples were determined by several multielement and element-specific techniques, including inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS), ion

Jun Hu; Baoshan Zheng; Robert B. Finkelman; Binbin Wang; Mingshi Wang; Shehong Li; Daishe Wu

2006-01-01

192

Permanent magnet synchronous motor with exterior-rotor : Distributed or concentrated windings – motor performance comparison  

Microsoft Academic Search

Purpose – The paper aims to present the comparison between the performances of the exterior-rotor permanent magnet synchronous motors with distributed windings and the performances of the exterior-rotor permanent magnet synchronous motors with concentrated windings. Design\\/methodology\\/approach – Finite element method is used for motors performance determination. The BLDC operation mode for the motors with different slot and pole number combination

Bojan Štumberger; Gorazd Štumberger; Miralem Hadžiselimovi?; Ivan Zagradišnik; Anton Hamler; Mladen Trlep

2006-01-01

193

Liposomes as drug delivery vehicles for boron agents  

Microsoft Academic Search

The successful treatment of cancer by boron neutroncapture therapy (BNCT) requires the selective concentration ofboron-10 within malignant tumors. The potential of liposomesto deliver boron-rich compounds to tumors has beenassessed by examination of the biodistribution of borondelivered by liposomes in tumor-bearing mice. Small unilamellarvesicles have been found to stably encapsulate highconcentrations of water-soluble ionic boron compounds. Alternatively, lipophilicboron-containing species have been

M. Frederick Hawthorne; Kenneth Shelly

1997-01-01

194

Development of boron reduction system for sea water desalination  

Microsoft Academic Search

Since boron has been showing to induce male reproductive impediments in laboratory animals, the 1993 WHO guidelines for drinking water quality set the recommended guideline value at 0.3 mg boron\\/l based on the NOEL (no-observed-adverse-effect level). Since boron is not effectively removed by the conventional water treatment not only for drinking water and domestic wastewater treatment, the concentration in ambient

Yasumoto Magara; Akihisa Tabata; Minoru Kohki; Mutsuo Kawasaki; Masahiko Hirose

1998-01-01

195

Effects assessment: Boron compounds in the aquatic environment  

Microsoft Academic Search

In previous studies, boron compounds were considered to be of comparatively low toxicity in the aquatic environment, with predicted no effect concentration (PNEC) values ranging around 1mgB\\/L (expressed as boron equivalent). In the present study, we describe an evaluation of toxicity data for boron available for the aquatic environment by different methods.For substances with rich datasets, it is often possible

Lucia Schoderboeck; Simone Mühlegger; Annemarie Losert; Christian Gausterer; Romana Hornek

2011-01-01

196

Selenium accumulation, distribution and speciation in spineless prickly pear cactus: a salt, boron, and drought tolerant, selenium-enriched nutraceutical fruit crop.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Prickly pear cactus (Opuntia) may be an alternative crop to grow in drainage-impacted regions of the westside of California, where high levels of salinity, selenium (Se), and boron (B) are present. Preliminary trials have demonstrated that Opuntia can tolerate the adverse soil conditions, while accu...

197

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

Microsoft Academic Search

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

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

2005-01-01

198

Pharmacokinetics in melanoma-bearing mice of 5-dihydroxyboryl-6-propyl-2-thiouracil (BPTU), a candidate compound for boron neutron capture therapy.  

PubMed Central

Blood pharmacokinetics and tissue distribution of 5-dihydroxyboryl-6-propyl-2-thiouracil (BPTU), a boron carrier with postulated melanin-seeking properties for boron neutron capture therapy, were determined in C57/BL mice with subcutaneous pigmented or non-pigmented B16 melanomas. Borocaptate sodium (BSH) was used as a boron compound without melanin-seeking properties in a comparative biodistribution study in the same animal tumour models. Administration of single doses showed that BPTU was retained better in the pigmented B16 tumour than in the non-pigmented variant. BPTU was found in large concentrations in kidney and liver. Brain boron was approximately 10-fold lower than tumour boron. On a molar basis, BPTU demonstrated higher affinity for B16 tumours than BSH. Owing to solubility limits, tumour boron concentrations in this mouse study were too low for effective application of BNCT. However, the high tumour-to-blood and tumour-to-normal tissues ratios indicate that, with appropriate formulation, BPTU could be a promising candidate for clinical BNCT.

Verrijk, R.; Smolders, I. J.; Huiskamp, R.; Gavin, P. R.; Philipp, K. H.; Begg, A. C.

1994-01-01

199

Properties of boron/boron-nitride multilayers  

SciTech Connect

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

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

1996-06-01

200

Boron neutron capture therapy for malignant gliomas.  

PubMed

Boron neutron capture therapy (BNCT) represents a promising modality for a relatively selective radiation dose delivery to the tumour tissue. Boron-10 nuclei capture slow 'thermal' neutrons preferentially and, upon capture, promptly undergo 10B(n,alpha)7Li reaction. The ionization tracks of energetic and heavy lithium and helium ions resulting from this reaction are only about one cell diameter in length (approximately 14 microm). Because of their high linear energy transfer (LET) these ions have a high relative biological effectiveness (RBE) for controlling tumour growth. The key to effective BNCT of tumours, such as glioblastoma multiforme (GBM), is the preferential accumulation of boron-10 in the tumour, including the infiltrating GBM cells, as compared with that in the vital structures of the normal brain. Provided that a sufficiently high tumour boron-10 concentration (approximately 10(9) boron-10 atoms/cell) and an adequate thermal neutron fluence (approximately 10(12) neutrons/cm2) are achieved, it is the ratio of the boron-10 concentration in tumour cells to that in the normal brain cells that will largely determine the therapeutic gain of BNCT. PMID:10711581

Diaz, A Z; Coderre, J A; Chanana, A D; Ma, R

2000-02-01

201

LFERs for soil organic carbon-water distribution coefficients (Koc) at environmentally relevant sorbate concentrations.  

PubMed

Organic carbon-water distribution coefficients, Koc, for organic compounds at environmentally relevant, low sorbate concentrations may substantially differ from those at higher concentrations due to nonlinear sorption to soil organic matter. However, prediction methods for Koc such as linear free energy relationships (LFERs) are currently only available for high sorbate concentrations (i.e., near solubility limits), reflecting the lack of a set of consistent experimental data in an environmentally more relevant concentration range (i.e., orders of magnitude lower than solubilities). In this study, we determined Koc for two model sorbents of soil organic matter, peat and lignite, at sorbate concentrations of 4.3 and 19 mg/kg-organic-carbon, respectively, in batch suspensions. The measured Koc values for organic sorbates (51 for peat, 58 for lignite) of varying sizes and polarities were modeled successfully with polyparameter linear free energy relationships (PP-LFERs). The resulting PP-LFER for peat was significantly different from the PP-LFERs in the literature determined at near aqueous solubility limits of sorbates. The literature PP-LFERs were found to underestimate the measured Koc values for peat at the low concentration by up to 1 order of magnitude. The extent of underestimation highly depends on the sorbate properties and can be explained by differing sorption nonlinearities of the sorbates as predicted by a reported empirical relationship between the nonlinearity in peat and the sorbate dipolarity/polarizability parameter S. Lignite appearsto be a stronger sorbent toward many sorbates than typical soil organic matter irrespective of the concentration range and thus may not be representative for organic matter with regard to the magnitude of Koc. The present study offers the first PP-LFER equation for log Koc in soil organic matter at typical environmental sorbate concentrations. PMID:19534119

Endo, Satoshi; Grathwohl, Peter; Haderlein, Stefan B; Schmidt, Torsten C

2009-05-01

202

Aerosol size distribution and mass concentration measurements in various cities of Pakistan.  

PubMed

During March and April 2010 aerosol inventories from four large cities in Pakistan were assessed in terms of particle size distributions (N), mass (M) concentrations, and particulate matter (PM) concentrations. These M and PM concentrations were obtained for Karachi, Lahore, Rawalpindi, and Peshawar from N concentrations using a native algorithm based on the Grimm model 1.109 dust monitor. The results have confirmed high N, M and PM concentrations in all four cities. They also revealed major contributions to the aerosol concentrations from the re-suspension of road dust, from sea salt aerosols, and from vehicular and industrial emissions. During the study period the 24 hour average PM(10) concentrations for three sites in Karachi were found to be 461 ?g m(-3), 270 ?g m(-3), and 88 ?g m(-3), while the average values for Lahore, Rawalpindi and Peshawar were 198 ?g m(-3), 448 ?g m(-3), and 540 ?g m(-3), respectively. The corresponding 24 hour average PM(2.5) concentrations were 185 ?g m(-3), 151 ?g m(-3), and 60 ?g m(-3) for the three sites in Karachi, and 91 ?g m(-3), 140 ?g m(-3), and 160 ?g m(-3) for Lahore, Rawalpindi and Peshawar, respectively. The low PM(2.5)/PM(10) ratios revealed a high proportion of coarser particles, which are likely to have originated from (a) traffic, (b) other combustion sources, and (c) the re-suspension of road dust. Our calculated 24 hour averaged PM(10) and PM(2.5) concentrations at all sampling points were between 2 and 10 times higher than the maximum PM concentrations recommended by the WHO guidelines. The aerosol samples collected were analyzed for crustal elements (Al, Fe, Si, Mg, Ca) and trace elements (B, Ba, Cr, Cu, K, Na, Mn, Ni, P, Pb, S, Sr, Cd, Ti, Zn and Zr). The averaged concentrations for crustal elements ranged from 1.02 ± 0.76 ?g m(-3) for Si at the Sea View location in Karachi to 74.96 ± 7.39 ?g m(-3) for Ca in Rawalpindi, and averaged concentrations for trace elements varied from 7.0 ± 0.75 ng m(-3) for B from the SUPARCO location in Karachi to 17.84 ± 0.30 ?g m(-3) for Na at the M. A. Jinnah Road location, also in Karachi. PMID:21677943

Alam, Khan; Blaschke, Thomas; Madl, Pierre; Mukhtar, Azam; Hussain, Majid; Trautmann, Thomas; Rahman, Said

2011-06-15

203

Submicron aerosol distributions and CCN concentration at Gosan and Seoul, Korea  

NASA Astrophysics Data System (ADS)

Submicron aerosol size distributions and total particle (i.e., condensation nuclei, CN) concentrations and cloud condensation nuclei (CCN) concentrations were measured at Gosan, Jeju Islands, Korea, in August 2006. A TSI SMPS model 3936L10 was used to measure aerosol size distributions every 3 minute, and a TSI CPC model 3010 and a model 3025 were used to measure the concentrations of aerosols having diameters larger than 10 nm and 3 nm, respectively, every 1 minute. CCN concentrations at 0.2%, 0.4%, 0.6%, 0.8% and 1.0% supersaturations (S) were measured every 25 minutes with a Droplet Measurement Technologies (DMT)¢¢ç¯ CCN Counter. Complete CCN spectra (0.02-1% S) were also measured with the two Desert Research Institute (DRI) instantaneous CCN spectrometers every 20 seconds. The Gosan site is located on a cliffy hill (approx. 50 m ASL) at the western tip of the Jeju Islands¢¢ç¯ coastline. The site is one of the key locations to monitor the influence of Asian continental outflow. Measurements were made in an instrument shelter from August 19^{th} to August 31^{st}. For the aerosols having diameter larger than 3 nm, its number concentrations were usually in the range of 5000 - 15000 cm-3. Occasionally the abrupt increases in the concentration were recorded near the noon time, with their peak concentration reaching several tens of thousands per cubic centimeter and lasting 2 to 5 hours. Such increases were due to the increased concentrations of aerosols having diameter between 3 nm and 10 nm, implying that the secondary aerosol formation and growth was taking place over the site during such periods. The geometric mean diameter (Dg) of aerosols having diameters between 10 and 500 nm usually fell in the range of 50 - 150 nm but it was as low as 20 nm during the aerosol formation events. For the CCN measurements, the two sets of instruments (DRI and DMT) having different measuring principle agreed well. CCN concentrations at 1 % S measured by the DMT CCN Counter fell in the range of 400 - 8000 cm-3. The CCN/CN ratios were below 1 for the whole period and were low when Dg were low and high when the Dg were high showing that the CCN measurements were consistent with other aerosol measurements. Additional measurement will be made in Seoul, the capital of Korea, with 10 million inhabitants, in September and October 2006. Further analysis and comparison including Seoul measurements will be presented at the conference.

Kim, J.; Lee, S.; Yum, S. S.; Hudson, J. G.

2006-12-01

204

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

205

NDP (neutron depth profiling) evaluations of boron-implanted compound semiconductors  

SciTech Connect

This report describes recent neutron depth profiling (NDP) experiments on the distribution of implanted boron in several semiconductors. The objectives are to compare the boron profiles for different materials that had been simultaneously implanted and to assess the effects of annealing treatments that were used to remove implant damage and electrically activate the boron.

Bowman, R.C.; Knudsen, J.F.; Downing, R.G.

1988-03-04

206

Spatial distribution and interannual variation of surface PM10 concentrations over eighty-six Chinese cities  

NASA Astrophysics Data System (ADS)

The spatial distribution of the aerosols over 86 Chinese cities was reconstructed from air pollution index (API) records for summer 2000 to winter 2006. PM10 (particulate matter ?10 ?m) mass concentrations were calculated for days when PM10 was the principal pollutant, these accounted for 91.6% of the total 150 428 recorded days. The 83 cities in mid-eastern China (100° E to 130° E) were separated into three latitudinal zones using natural landscape features as boundaries. Areas with high PM10 level in northern China (127 to 192 ?g m-3) included Urumchi, Lanzhou-Xining, Weinan-Xi'an, Taiyuan-Datong-Yangquan-Changzhi, Pingdingshan-Kaifeng, Beijing-Tianjin-Shijiazhuang, Jinan, and Shenyang-Anshan-Fushun; in the middle zone, high PM10 (119-147 ?g m-3) occurred at Chongqing-Chengdu-Luzhou, Changsha-Wuhan, and Nanjing-Hangzhou; in the southern zone, only four cities (Qujing, Guiyang, Guangzhou and Shaoguan) showed PM10 concentration >80 ?g m-3. The median PM10 concentration decreased from 108 ?g m-3 for the northern cities to 95 ?g m-3 and 55 ?g m-3 for the middle and southern zones, respectively. PM10 concentration and the APIs both exhibited wintertime maxima, summertime minima, and the second highest values in spring. PM10showed evidence for a decreasing trend for the northern cities while in the other zones urban PM10 levels fluctuated, but showed no obvious change over time. The spatial distribution of PM10 was compared with the emissions, and the relationship between the surface PM10 concentration and the aerosol optical depth (AOD) was also discussed.

Qu, W. J.; Arimoto, R.; Zhang, X. Y.; Zhao, C. H.; Wang, Y. Q.; Sheng, L. F.; Fu, G.

2010-06-01

207

Testing an agent-based model of bacterial cell motility: How nutrient concentration affects speed distribution  

NASA Astrophysics Data System (ADS)

We revisit a recently proposed agent-based model of active biological motion and compare its predictions with own experimental findings for the speed distribution of bacterial cells, Salmonella typhimurium. Agents move according to a stochastic dynamics and use energy stored in an internal depot for metabolism and active motion. We discuss different assumptions of how the conversion from internal to kinetic energy d( v) may depend on the actual speed, to conclude that d 2 v ? with either ? = 2 or 1 < ? < 2 are promising hypotheses. To test these, we compare the model's prediction with the speed distribution of bacteria which were obtained in media of different nutrient concentration and at different times. We find that both hypotheses are in line with the experimental observations, with ? between 1.67 and 2.0. Regarding the influence of a higher nutrient concentration, we conclude that the take-up of energy by bacterial cells is indeed increased. But this energy is not used to increase the speed, with 40 ?m/s as the most probable value of the speed distribution, but is rather spend on metabolism and growth.

Garcia, V.; Birbaumer, M.; Schweitzer, F.

2011-08-01

208

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

209

Roles of BOR1, DUR3, and FPS1 in boron transport and tolerance in Saccharomyces cerevisiae  

Microsoft Academic Search

The roles of three membrane proteins, BOR1, DUR3, and FPS1, in boron (B) transport in yeast were examined. The boron concentration in yeast cells lacking BOR1 was elevated upon exposure to 90mM boric acid, whereas cells lacking DUR3 or FPS1 showed lower boron concentrations. Compared with control cells, cells overexpressing BOR1 or FPS1 had a lower boron concentration, and cells

Akira Nozawa; Junpei Takano; Masaharu Kobayashi; Toru Fujiwara

2006-01-01

210

Comparative effects of daily and weekly boron supplementation on plasma steroid hormones and proinflammatory cytokines  

Microsoft Academic Search

Boron possesses widespread properties in biochemistry and nutrition. Acute supplementation with 11.6mg of boron resulted in a significant increase in plasma boron concentration. Given such a fast bioavailability, the objective was to determine whether acute (hourly or daily), and weekly supplementation could have any significant biological effects on the steroid hormones and further on some inflammatory biomarkers. Eight healthy male

Mohammad Reza Naghii; Mahmoud Mofid; Ali Reza Asgari; Mehdi Hedayati; Maryam-Saddat Daneshpour

2011-01-01

211

Influence of pH in the elimination of boron by means of reverse osmosis  

Microsoft Academic Search

The European Union (EU) stipulates the maximum admissible value for the concentration of boron at 1 ppm and the World Health Organization (WHO) at 0.3 ppm as the non-observed effect level (NOEL) for drinking water. The content of boron in water can be reduced by means of various processes. Treatment by means of conventional reverse osmosis only reduces the boron

M. Rodríguez Pastor; A. Ferrándiz Ruiz; M. F. Chillón; D. Prats Rico

2001-01-01

212

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

2012-08-10

213

Radial distribution of the flow velocity, efficiency and concentration in a wide HPLC column  

SciTech Connect

The use of optical fibers in a fluorescence-detection scheme permits the accurate determination of the radial distribution of the transit time, the column efficiency, and the analyte concentration at the exit of a chromatographic axial-compression column (50 mmID). The results obtained demonstrate that the column is not homogeneous, but suggest a nearly cylindrical distribution of the packing density. The average velocity close to the column wall is 7% lower than along its axis and the HETP 25% higher. The lack of homogeneity of the column packing is another source of band broadening not taken into account in chromatography so far. It causes the apparent HETP derived from the conventional elution chromatogram recorded on the bulk eluent to be larger than the local HETP and the band profile to be unsymmetrical with a slight tail reminiscent of kinetic tailing.

Farkas, T.; Sepaniak, M.J.; Guiochon, G. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States). Div. of Chemical and Analytical Sciences

1997-08-01

214

Variation of particle number concentration and size distributions at the urban environment in Vilnius (Lithuania)  

NASA Astrophysics Data System (ADS)

This study presents results of research on urban aerosol particles with a focus on the particle size distribution and the aerosol particle number concentration (PNC). The real time measurements of the aerosol PNC in the size range of 9-840 nm were performed at the urban background site using a Condensed Particle Counter and Scanning Mobility Particle Sizer (SMPS). Strong diurnal patterns in aerosol PNC were evident as a direct effect of three sources of the aerosol particles (nucleation, traffic, and residential heating appliances). The traffic exhaust emissions were a major contributor of the pollution observed at the roadside site that was dominated by the nucleation mode particles, while particles formed due to the residential heating appliances and secondary formation processes contributed to the accumulation mode particles and could impact the variation of PNC and its size distribution during the same day.

Ulevicius, Vidmantas; By?enkien?, Steigvil?; Plauškait?, Kristina; Dudoitis, Vadimas

2013-05-01

215

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

PubMed

Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing boron as a major undesirable element. The kinetics process of boron sorption by uncalcined hydrotalcite is controlled by the diffusion of boron from bulk solution to sorbent-solution boundary film and its exchange with interlayer chloride of hydrotalcite, whereas the removal rate of boron by calcined hydrotalcite rests with the restoration process of its layered structure. The results of isotherm sorption experiments reveal that calcined hydrotalcite generally has much stronger ability to lower solution boron concentration than uncalcined hydrotalcite. The combination of adsorption of boron on the residue of MgO-Al2O3 solid solution and intercalation of boron into the reconstructed hydrotalcite structure due to "structural memory effect" is the basic mechanism based on which the greater boron removal by calcined hydrotalcite was achieved. As 15 geothermal water samples were used to test the deboronation ability of calcined hydrotalcite at 65 °C, much lower boron removal efficiencies were observed. The competitive sorption of the other anions in geothermal water, such as HCO3 (-), SO4 (2-), and F(-), is the reason why calcined hydrotalcite could not remove boron from geothermal water as effectively as from pure boron solution. However, boron removal percents ranging from 89.3 to 99.0 % could be obtained if 50 times of sorbent were added to the geothermal water samples. Calcined hydrotalcite is a good candidate for deboronation of geothermal water. PMID:23695854

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

2013-05-22

216

Boron neutron capture therapy (BNCT): A radiation oncology perspective  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) offers considerable promise in the search for the ideal cancer therapy, a therapy which selectively and maximally damages malignant cells while sparing normal tissue. This bimodal treatment modality selectivity concentrates a boron compound in malignant cells, and then [open quotes]activates[close quotes] this compound with slow neutrons resulting in a highly lethal event within the cancer

Ronald V. Dorn

1994-01-01

217

Initial stages of growth during boron carbide chemical vapor deposition  

Microsoft Academic Search

The initial stages of growth of boron carbides from a BCl3\\/H2\\/hydrocarbon vapor on molybdenum were investigated. The initial growth of boron carbide was strongly dependent on the type and concentration of hydrocarbon in the vapor. From the results of the experiments it was concluded that an ''overlayer'' of adsorbed hydrocarbons was formed on the surface. The overlayer inhibited some reactions

Ulf Jansson; Jan-Otto Carlsson; Bengt Stridh

1987-01-01

218

Boron emitters: Defects at the silicon - silicon dioxide interface  

Microsoft Academic Search

An investigation of defects caused by boron diffusion into silicon is presented, using two techniques to directly compare the defects at an undiffused and lightly boron diffused Si-SiO2 interface. The first technique uses field effect passivation induced by a MOS structure; the second uses Electron Paramagnetic Resonance measurements to determine the concentration of unpassivated Pb centers on oriented surfaces. It

W. Jellett; C. Zhang; H. Jin; P. J. Smith; K. J. Weber

2008-01-01

219

Coaxial nanocable: Carbon nanotube core sheathed with boron nitride nanotube  

Microsoft Academic Search

A coaxial nanocable model consisting of conductive carbon nanotube core and boron nitride nanotube sheath is proposed by ab initio calculations. The conduction electron density is mainly concentrated on the inner carbon shell at the optimal interwall distance about 0.35 nm. The conductivity of the core carbon nanotube and the insulation of the boron nitride nanotube sheath are found to

Zhuhua Zhang; Wanlin Guo; Guo'an Tai

2007-01-01

220

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates  

Microsoft Academic Search

The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80

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

1991-01-01

221

Influence of soil solution salinity on boron adsorption by soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Boron adsorption on two arid-zone soils from the San Joaquin Valley of California was investigated as a function of equilibrium solution B concentration (0-250 mg L-1), solution pH (3-12), and electrical conductivity (EC = 0.3 or 7.8 dS m-1). Boron adsorption on both soils increased with increasing...

222

Imaging the Proton Concentration and Mapping the Spatial Distribution of the Electric Field of Catalytic Micropumps  

NASA Astrophysics Data System (ADS)

Catalytic engines can use hydrogen peroxide as a chemical fuel in order to drive motion at the microscale. The chemo-mechanical actuation is a complex mechanism based on the interrelation between catalytic reactions and electro-hydrodynamics phenomena. We studied catalytic micropumps using fluorescence confocal microscopy to image the concentration of protons in the liquid. In addition, we measured the motion of particles with different charges in order to map the spatial distributions of the electric field, the electrostatic potential and the fluid flow. The combination of these two techniques allows us to contrast the gradient of the concentration of protons against the spatial variation in the electric field. We present numerical simulations that reproduce the experimental results. Our work sheds light on the interrelation between the different processes at work in the chemomechanical actuation of catalytic pumps. Our experimental approach could be used to study other electrochemical systems with heterogeneous electrodes.

Farniya, A. Afshar; Esplandiu, M. J.; Reguera, D.; Bachtold, A.

2013-10-01

223

Roles of ATR1 paralogs YMR279c and YOR378w in boron stress tolerance  

Microsoft Academic Search

Boron is a necessary nutrient for plants and animals, however excess of it causes toxicity. Previously, Atr1 and Arabidopsis Bor1 homolog were identified as the boron efflux pump in yeast, which lower the cytosolic boron concentration and help cells to survive in the presence of toxic amount of boron. In this study, we analyzed ATR1 paralogs, YMR279c and YOR378w, to

Gonensin Ozan Bozdag; Irem Uluisik; Gulce Sila Gulculer; Huseyin C. Karakaya; Ahmet Koc

2011-01-01

224

Interactions of bulk-boronized graphites with deuterium plasmas in the Pisces-B facility  

Microsoft Academic Search

Newly developed bulk-boronized graphites and boronized carbon-carbon composites, with a total boron concentration ranging from 3 to 30 wt %, have been bombarded with steady-state deuterium plasmas at temperatures between 200 and 1600°C in the PISCES-B facility. The erosion yield of bulk-boronized graphite is smaller than that of pyrolytic graphite by a factor of 2 to 3 in regimes of

Y. Hirooka; R. W. Conn; M. J. Khandagle; G. Chevalier; T. Sogabe; T. Marsuda; H. Ogura; H. Toyoda; H. Sugai

1991-01-01

225

Boron toxicity  

Microsoft Academic Search

Whilst of lesser prevalence than B deficient soils, B-rich soils are important, causing B toxicity in the field and decreased crop yields in different regions of the world. The highest naturally occurring concentrations of soil B are in soils derived from marine evaporites and marine argillaceous sediment. In addition, various anthropogenic sources of excess B may increase soil B to

Ross O. Nable; Gary S. Bañuelos; Jeffrey G. Paull

1997-01-01

226

An application of passive samplers to understand atmospheric mercury concentration and dry deposition spatial distributions.  

PubMed

Two modified passive samplers were evaluated at multiple field locations. The sampling rate (SR) of the modified polyurethane foam (PUF)-disk passive sampler for total gaseous mercury (TGM) using gold-coated quartz fiber filters (GcQFF) and gaseous oxidized mercury (GOM) using ion-exchange membranes (IEM) were 6.4 ± 1.4 and 15.3 ± 0.3 m(3) day(-1), respectively. The relative percent difference between TGM and GOM concentrations measured by a Tekran system and the passive samplers averaged 19 ± 14 and 13 ± 12% and ranged between 4-44 and 1.5-41%, respectively. The GcQFF and IEM substrates were also evaluated as collection media for surrogate surface dry deposition measurements. Mercury (Hg) concentration and dry deposition gradients were observed using these samplers at an urban/industrial site and compared to a rural/remote site. The Hg dry deposition rates measured by the surrogate surfaces were always higher than those calculated by a widely used inferential modeling method (1.3-50 fold). The Hg dry deposition measured at urban and suburban sites were comparable to those calculated from model. However, they were very different at a rural site, probably due to the low concentrations. Both methods are relatively low cost and will aid in understanding spatial distributions of Hg ambient air concentrations and dry deposition. PMID:23001454

Huang, Jiaoyan; Choi, Hyun-Deok; Landis, Matthew S; Holsen, Thomas M

2012-11-01

227

[Concentrations and distribution of tetracycline antibiotics in vegetable field soil chronically fertilized with manures].  

PubMed

Occurrence of antibiotics in the soils substantially fertilized with antibiotics-enriched animal manures is very of concern. This paper investigated the concentration and distribution of four tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area using solid-phase extraction followed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS). The sum concentrations of four tetracycline compounds ranged from 1.35 microg/kg to 22.52 microg/kg with an average of 7.35 microg/kg. There were thirty one to one hundred percent of the soil samples were detected with average concentrations of 0.63- 3.11 microg/kg for four tetracycline compounds which dominated mostly with oxytetracycline and secondly with deoxytetracycline. Composition and levels of tetracycline compounds varied obviously in both horizontal and vertical soils. The concentration of tetracycline compounds in soil profile decreased rapidly with the depth and some of the compounds were still detected in 60 to 80 centimeter depth of soil. It is concluded that tetracycline antibiotics in soils from vegetable field chronically fertilized with manures in subtropical area were generally lower and less ecotoxic risk for soil ecosystem. But it should not be ignored in view of combined toxic effect and resistance of various compounds. PMID:21717767

Tai, Yi-Ping; Mo, Ce-Huij; Li, Yan-Wen; Wu, Xiao-Lian; Duan, Xia-Zhen; Qu, Xiang-Long; Huang, Xian-Pei

2011-04-01

228

Integrating Mechanisms that Control the Concentration and Distribution of Groundwater Arsenic in Cambodia  

NASA Astrophysics Data System (ADS)

Arsenic contamination in the groundwater of the deltaic regions of southeastern Asia affects as many as one hundred million people. In these areas, the dominant mechanism for arsenic release into solution is the reductive dissolution of arsenic-bearing iron (hydr)oxides. What continues to confound researchers, however, is the heterogeneous nature of arsenic in groundwater. Recent evidence suggests that specific geomorphic environments are linked to regions of elevated groundwater arsenic. Moreover, waters from actively cycling surficial environments represent important sources of groundwater As in many environments. Here, we examine the mechanistic link between the localized expression of iron reduction and the large scale distribution of arsenic in groundwater along the Mekong River in Cambodia in a region impacted by widespread but heterogeneous arsenic contamination. In this region, arsenic levels in groundwater were correlated to sulfate levels, and both were strongly influenced by the extent of local surface water flooding (as quantified by remote sensing). Concentrations of arsenic ranged from 0 to 2100 micrograms/L, and were always found in groundwaters with significant dissolved iron and a sulfate concentration less than 1 mg/L. This indicates that the delivery of As and S was influenced by active redox processes in near-surface environments. In many, but not all, high As regions, groundwater concentrations of conservative halide anions also were similar to those of surficial environments, indicating that they were likely derived from the same locations. Low As regions, however, had widely variable halide concentrations in groundwater that may reflect additional groundwater sources. Thus, the expression of As contamination is strongly influenced by the hydrological connectivity of the aquifer with the surface. The isotopic composition of groundwater (hydrogen and oxygen) of high As areas also is similar to that of surface waters. Dissolved inorganic carbon isotopic composition of waters is more complex, with As-impacted groundwaters having distinct isotopic signatures characteristic of either extensive or relatively limited organic matter decomposition. Regional correlations of As with dissolved organic carbon are also not uniform, suggesting that sedimentary carbon is also important in generating reducing conditions. These data indicate that the distribution of organic carbon helps determine the distribution of arsenic in the environment. Moreover, these data indicate that heterogeneity in arsenic concentrations results from the interplay of variable organic matter content and reactivity within complex hydrological systems that can at least in part be explained regionally based on depositional environment.

Bostick, B. C.; Rosen, E. L.; Nguyen, H. M.; Sampson, M. L.

2008-12-01

229

Boron removal from drinking water with a boron selective resin: is the treatment really selective?  

Microsoft Academic Search

Drinking water and even mineral water may contain boron until a few ppm and WHO has recommended a limit of 0.3mg boronl?1. The treatment by the resin Amberlite IRA743 seems to be the most convenient. Water deboronation with this resin has been revisited through laboratory column experiments, especially for low boron concentrations. Given that the resin bears weakly basic anion

Marie-Odile Simonnot; Christophe Castel; Miguel NicolaÏ; Christophe Rosin; Michel Sardin; Henri Jauffret

2000-01-01

230

Concentration and distribution of copper and cadmium in water, sediments, detritus, plants and animals in a hardwater lowland river  

Microsoft Academic Search

The concentration and distribution of copper (Cu) and cadmium (Cd) were examined in water, sediments, detritus, plants and animals in a small, lowland, hardwater river. Consistently higher concentrations of Cu and Cd were found in all types of samples from two sites. There were marked variations in metal concentrations between different types of samples, and between seasons. Copper and Cd

S. Smith; M.-H. Chen; R. G. Bailey; W. P. Williams

1996-01-01

231

Geostatistical analysis of the spatial distribution of mycotoxin concentration in bulk cereals.  

PubMed

Deoxynivalenol (DON) and ochratoxin A (OTA) in agricultural commodities present hazards to human and animal health. Bulk lots are routinely sampled for their presence, but it is widely acknowledged that designing sampling plans is particularly problematical because of the heterogeneous distribution of the mycotoxins. Previous studies have not explicitly looked at the interactions between the spatial distribution of the mycotoxin and the strategy used to take samples from bulk. Sampling plans are therefore designed on the assumption of random distributions. The objective of this study was to analyse the spatial distribution of DON and OTA in bulk commodities with geostatistics. This study was the first application of geostatistical analysis to data on mycotoxins contamination of bulk commodities. Data sets for DON and OTA in bulk storage were collected from the literature and personal communications, of which only one contained data suitable for geostatistical analysis. This data set represented a 26-tonne truck of wheat with a total of 100 sampled points. The mean concentrations of DON and OTA were 1342 and 0.59 microg kg(-1), respectively. The results showed that DON presented spatial structure, whilst OTA was randomly distributed in space. This difference between DON and OTA probably reflected the fact that DON is produced in the field, whereas OTA is produced in storage. The presence of spatial structure for DON implies that sampling plans need to consider the location of sample points in addition to the number of points sampled in order to obtain reliable estimates of quantities such as the mean contamination. PMID:19680962

Rivas Casado, M; Parsons, D J; Weightman, R M; Magan, N; Origgi, S

2009-06-01

232

Evolution of root plasticity responses to variation in soil nutrient distribution and concentration  

PubMed Central

Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However, the effects of domestication on the evolution of root plasticity are essentially unknown. Using a split container approach, we examined the differences in root plasticity among three domestication levels of barley germplasm (wild, landrace, and cultivar) grown under different concentrations and distribution patterns of soil nutrients. Domestication level, nutrient concentration, and nutrient distribution interactively affected average root diameter; differential root allocation (within-plant plasticity) was greatest in wild barley (Hordeum spontaneum), especially under low nutrient levels. Correlations of within-plant root plasticity and plant size were most pronounced in modern cultivars under low-nutrient conditions. Barley plants invested more resources to root systems when grown in low-nutrient soils and allocated more roots to higher-nutrient locations. Root plasticity in barley is scale dependent and varies with domestication level. Although wild barley harbors a greater capacity for within-plant root plasticity than domesticated barley, cultivars exhibited the greatest capacity to translate within-plant plasticity into increased plant size.

Grossman, Judah D; Rice, Kevin J

2012-01-01

233

Distribution of Genetic Marker Concentrations for Fecal Indicator Bacteria in Sewage and Animal Feces  

PubMed Central

Very little is known about the density and distribution of fecal indicator bacteria (FIB) genetic markers measured by quantitative real-time PCR (qPCR) in fecal pollution sources. Before qPCR-based FIB technologies can be applied to waste management and public health risk applications, it is vital to characterize the concentrations of these genetic markers in pollution sources (i.e., untreated wastewater and animal feces). We report the distribution of rRNA genetic markers for several general FIB groups, including Clostridium spp., Escherichia coli, enterococci, and Bacteroidales, as determined by qPCR on reference collections consisting of 54 primary influent sewage samples collected from treatment facilities across the United States and fecal samples representing 20 different animal species. Based on raw sewage sample collection data, individual FIB genetic markers exhibited a remarkable similarity in concentration estimates from locations across the United States ranging from Hawaii to Florida. However, there was no significant correlation between genetic markers for most FIB combinations (P > 0.05). In addition, large differences (up to 5 log10 copies) in the abundance of FIB genetic markers were observed between animal species, emphasizing the importance of indicator microorganism selection and animal source contribution for future FIB applications.

Kelty, Catherine A.; Varma, Manju; Sivaganesan, Mano; Haugland, Richard A.

2012-01-01

234

Uranium concentration and distribution in six peridotite inclusions of probable mantle origin  

NASA Astrophysics Data System (ADS)

Fission-track activation was used to investigate uranium concentration and distribution in peridotite inclusions in alkali basalt from six localities. Whole-rock uranium concentrations range from 24 to 82 ng/g (1ng= 10 -9g). Most of the uranium is uniformly distributed in the major silicate phases — olivine, orthopyroxene, and clinopyroxene. Chromian spinels may be classified into two groups on the basis of their uranium content, having either less than 10 ng/g or 100-150 ng/g U. In one sample accessory hydrous phases, phlogopite and hornblende, contain 130 and 300 ng/g U, respectively. The contact between the inclusion and the host basalt is usually quite sharp. Glassy or microcrystalline veinlets found in some samples contain more than 1?g/g(1 ?g= 10 -6g). Very little uranium is associated with microcrystals of apatite. Our results agree with some earlier investigators, who have concluded that suboceanic peridotites contain too little uranium to account for normal oceanic heat flow by conduction alone.

Haines, Eldon L.; Zartman, Robert E.

1973-09-01

235

Concentration and distribution of cobalt in higher plants: The use of micro-PIXE spectroscopy  

NASA Astrophysics Data System (ADS)

Cobalt is not classified as an essential element for plants, however, it is usually described as “beneficial”. This trace element can be a contaminant in soils due to agricultural additives or metal refineries. Certain plants species have the ability to extract metals (such as Co) from soils, thus, cleaning the environment. Therefore, knowledge of the physiological mechanisms of metal absorption is required to improve these phytoremediation technologies. Patterns of cobalt accumulation and storage were determined in tomato (Lycopersicon esculentum) and wheat (Triticum aestivum) species. Plants were grown in nutrient solutions, with different Co treatments, using controlled environmental conditions. The spatial distributions of K, Ca, Fe and Co in whole plants, and in leaf and stem sections, were examined by micro-PIXE. In conjunction, total Co concentrations were determined by ICP-MS. Micro-PIXE spectroscopy proved to be a convenient technique for indicating Co concentrations and distribution patterns in these plants. This knowledge aids in the identification of vegetal Co sequestration and, thus, helps to unravel how Co is transported in higher plants.

Bakkaus, E.; Gouget, B.; Gallien, J.-P.; Khodja, H.; Carrot, F.; Morel, J. L.; Collins, R.

2005-04-01

236

Evidence for a bimodal distribution of Escherichia coli doubling times below a threshold initial cell concentration  

PubMed Central

Background In the process of developing a microplate-based growth assay, we discovered that our test organism, a native E. coli isolate, displayed very uniform doubling times (?) only up to a certain threshold cell density. Below this cell concentration (? 100 -1,000 CFU mL-1 ; ? 27-270 CFU well-1) we observed an obvious increase in the ? scatter. Results Working with a food-borne E. coli isolate we found that ? values derived from two different microtiter platereader-based techniques (i.e., optical density with growth time {=OD[t]} fit to the sigmoidal Boltzmann equation or time to calculated 1/2-maximal OD {=tm} as a function of initial cell density {=tm[CI]}) were in excellent agreement with the same parameter acquired from total aerobic plate counting. Thus, using either Luria-Bertani (LB) or defined (MM) media at 37°C, ? ranged between 17-18 (LB) or 51-54 (MM) min. Making use of such OD[t] data we collected many observations of ? as a function of manifold initial or starting cell concentrations (CI). We noticed that ? appeared to be distributed in two populations (bimodal) at low CI. When CI ?100 CFU mL-1 (stationary phase cells in LB), we found that about 48% of the observed ? values were normally distributed around a mean (??1) of 18 ± 0.68 min (± ??1) and 52% with ??2 = 20 ± 2.5 min (n = 479). However, at higher starting cell densities (CI>100 CFU mL-1), the ? values were distributed unimodally (?? = 18 ± 0.71 min; n = 174). Inclusion of a small amount of ethyl acetate to the LB caused a collapse of the bimodal to a unimodal form. Comparable bimodal ? distribution results were also observed using E. coli cells diluted from mid-log phase cultures. Similar results were also obtained when using either an E. coli O157:H7 or a Citrobacter strain. When sterile-filtered LB supernatants, which formerly contained relatively low concentrations of bacteria(1,000-10,000 CFU mL-1), were employed as a diluent, there was an evident shift of the two populations towards each other but the bimodal effect was still apparent using either stationary or log phase cells. Conclusion These data argue that there is a dependence of growth rate on starting cell density.

2010-01-01

237

The Advection-Diffusion Problem for Stratospheric Flow. Part I: Concentration Probability Distribution Function.  

NASA Astrophysics Data System (ADS)

The mixing of a passive tracer by realistic time-dependent stratospheric flow (European Centre for Medium-Range Weather Forecasts winds) on an isentropic surface (420 K) is studied. Simulations of the advection-diffusion problem for an initially large-scale tracer field are carried out in the limit of weak diffusivity. Owing to chaotic advection, tracer variance is cascaded to small scales, where it can be dissipated despite the weak diffusivity. The tracer fluctuations are characterized in terms of their probability distribution function (PDF). The PDFs are characterized by a Gaussian core and `fat tails,' which fall more slowly than a Gaussian, and indicate anomalously high probability of extreme concentration fluctuations. Given the nonlinearity of many chemical reactions of interest, the anomalous prevalence of extreme fluctuations could have a profound effect on reactive tracers.Zonal variations of tracer are homogenized globally leading to a unimodal PDF. Initially meridional variations are strongly influenced by the presence of mixing barriers. Meridional gradients homogenize only within mixing zones of limited latitudinal extent, bounded by permeable mixing barriers. The PDF becomes multimodal, with distinct populations of air caused by blending of the concentration values within each mixing zone. The Tropics is a zone of weak mixing, and serves as an important repository of stratospheric tracers, which are episodically ejected into surf zones in the form of filaments bearing extreme concentration values.The shapes of the PDFs are discussed in terms of theoretical methods developed in the context of highly idealized mixing models. It is shown that such methods retain their utility when applied to realistic stratospheric mixing. The role of the probability distribution of finite-time Lyapunov exponents for the underlying trajectory problem is highlighted. The use of conditional averages of diffusion and dissipation is also illustrated. PDFs yielded by the idealized advection-diffusion problem are found to resemble those appearing in a GCM simulation of N2O.The theoretical arguments and numerical results imply that under the assumption that the diffusivity is set so that the dissipation scale is comparable to model resolution, the concentration PDF eventually reaches a universal shape independent of model resolution after an initial transient stage. However, the width of the distribution, or equivalently the variance of the tracer fluctuation, increases algebraically as model resolution is refined.

Hu, Y.; Pierrehumbert, R. T.

2001-06-01

238

Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China.  

PubMed

Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption. PMID:17166559

Duan, Jingchun; Bi, Xinhui; Tan, Jihua; Sheng, Guoying; Fu, Jiamo

2006-12-12

239

Fluorine-enhanced boron diffusion in germanium-preamorphized silicon  

SciTech Connect

Silicon wafers were preamorphized with 60 keV Ge{sup +} or 70 keV Si{sup +} at a dose of 1x10{sup 15} atoms/cm{sup 2}. F{sup +} was then implanted into some samples at 6 keV at doses ranging from 1x10{sup 14} to 5x10{sup 15} atoms/cm{sup 2}, followed by {sup 11}B{sup +} implants at 500 eV, 1x10{sup 15} atoms/cm{sup 2}. Secondary-ion-mass spectrometry confirmed that fluorine enhances boron motion in germanium-preamorphized materials in the absence of annealing. The magnitude of boron diffusion scales with increasing fluorine dose. Boron motion in as-implanted samples occurs when fluorine is concentrated above 1x10{sup 20} atoms/cm{sup 3}. Boron atoms are mobile in as-implanted, amorphous material at concentrations up to 1x10{sup 19} atoms/cm{sup 3}. Fluorine directly influences boron motion only prior to activation annealing. During the solid-phase epitaxial regrowth process, fluorine does not directly influence boron motion, it simply alters the recrystallization rate of the silicon substrate. Boron atoms can diffuse in germanium-amorphized silicon during recrystallization at elevated temperatures without the assistance of additional dopants. Mobile boron concentrations up to 1x10{sup 20} atoms/cm{sup 3} are observed during annealing of germanium-preamorphized wafers.

Jacques, J.M.; Jones, K.S.; Robertson, L.S.; Li-Fatou, A.; Hazelton, C.M.; Napolitani, E.; Rubin, L.M. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Texas Instruments Inc., Dallas, Texas 75243 (United States); Istituto Nazionale per la Fisica della Materia-Materials and Technologies for Information and Communication Science (INFM-MATIS) and Dipartimento di Fisica, via Marzolo 8, I-35131 Padova (Italy); Axcelis Technologies, Beverly, Massachusetts 01915 (United States)

2005-10-01

240

Electrical Properties of Silicon Containing Arsenic and Boron  

Microsoft Academic Search

Electrical conductivity and Hall effect have been measured from 10° to 1100° Kelvin on single-crystal silicon containing arsenic and boron. Extrinsic carrier concentration is computed from Hall coefficient. Analysis of extrinsic carrier concentration indicates the ionization energy of arsenic donor levels to be 0.049 ev and of boron acceptor levels to be 0.045 ev for low impurity concentrations. Fermi degeneracy

F. J. Morin; J. P. Maita

1954-01-01

241

Distribution of Airborne Radon-222 Concentrations in U.S. Homes  

NASA Astrophysics Data System (ADS)

Apparently large exposures of the general public to the radioactive decay products of radon-222 present in indoor air have led to systematical appraisal of monitoring data from U.S. single-family homes; several ways of aggregating data were used that take into account differences in sample selection and season of measurements. The resulting distribution of annual-average radon-222 concentrations can be characterized by an arithmetic mean of 1.5 picocurie per liter (55 becquerels per cubic meter) and a long tail with 1 to 3% of homes exceeding 8 picocuries per liter, or by a geometric mean of 0.9 picocurie per liter and a geometric standard deviation of about 2.8. The standard deviation in the means is 15%, estimated from the number and variability of the available data sets, but the total uncertainty is larger because these data may not be representative. Available dose-response data suggest that an average of 1.5 picocuries per liter contributes about 0.3% lifetime risk of lung cancer and that, in the million homes with the highest concentrations, where annual exposures approximate or exceed those received by under-ground uranium miners, long-term occupants suffer an added lifetime risk of at least 2%, reaching extraordinary values at the highest concentrations observed.

Nero, A. V.; Schwehr, M. B.; Nazaroff, W. W.; Revzan, K. L.

1986-11-01

242

3D-Simulation Of Concentration Distributions Inside Large-Scale Circulating Fluidized Bed Combustors  

NASA Astrophysics Data System (ADS)

With increasing size of modern CFB combustors the lateral mixing of fuels and secondary air gains more and more importance. Strong concentration gradients, which result from improper lateral mixing, can lead to operational problems, high flue gas emissions and lower boiler efficiencies. A 3D-model for the simulation of local gas and solids concentrations inside industrial-sized CFB boilers has been developed. The model is based on a macroscopic approach and considers all major mechanisms during fuel spreading and subsequent combustion of char and volatiles. Typical characteristics of modern boilers like staged combustion, a smaller cross-sectional area in the lower section of the combustion chamber and the co-combustion of additional fuels with coal can be considered. The 252 MWth combustor of Stadtwerke Duisburg AG is used for the validation of the model. A comprehensive picture of the local conditions inside the combustion chamber is achieved by the combination of local gas measurements and the three-dimensional simulation of concentration distributions.

Wischnewski, R.; Ratschow, L.; Hartge, E. U.; Werthe, J.

243

Molecular size distribution of compost-derived humates as a function of concentration and different counterions.  

PubMed

Conformational changes in the structures of humic acids (HA) extracted from compost with varying degrees of maturity were monitored by high performance size exclusion chromatography (HPSEC). The molecular size distribution of HA was compared in solutions containing sodium or ammonium counterions at pH 7 and pH 4.5. These findings indicate that the humates' molecular size depended not only on the nature of the counterions but also on their concentration in the solution. The physicochemical nature of sodium counterions determined smaller molecular sizes than those of the more hydrated ammonium counterions, at low concentrations of humates. Conversely, at higher humate concentrations, the more compact conformation of sodium humates produced larger molecular sizes than those of ammonium humates due to the aggregation of more hydrophobic surfaces in the sodium humates. Composting led to the degradation of labile microbial components with accumulation of hydrophobic constituents. This caused self-association of hydrophobic compounds into humic superstructures of larger molecular size over composting time. At lower pH, changes in conformational stability by the addition of acetic acid to humate solutions were explained by the supramolecular model of humified organic matter. PMID:18778847

Maia, Claudia M B F; Piccolo, Alessandro; Mangrich, Antonio S

2008-09-07

244

Magnetron sputter deposition of boron and boron carbide  

Microsoft Academic Search

The fabrication of x-ray optical coatings with greater reflectivity required the development of sputter deposition processes for boron and boron carbide. The use of high density boron and boron carbide and a vacuum brazed target design was required to achieve the required sputter process stability and resistance to the thermal stress created by high rate sputtering. The results include a

M. A. McKernan; D. Makowiecki; P. Ramsey; A. Jankowski

1991-01-01

245

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

246

Boron doped graphene nanoribbons  

Microsoft Academic Search

We will present a detailed study of the electronic, magnetic and transport properties of boron doped graphene nanoribbons, for various widths. The electronic structures and the equilibrium geometries were obtained through ab initio total energy DFT calculations. The transport properties were investigated using nonequilibrium Green's functions. Our results reveal that the substitutional boron atoms occupy the edge sites of nanoribbons,

Thiago Martins; Hiroki Miwa; Antonio J. R. da Silva; A. Fazzio

2007-01-01

247

ELECTROLYTIC PRODUCTION OF BORON  

Microsoft Academic Search

Elemental boron was produced by the fused salt electrolysis of potassium ; fluoborate. A study was made of anode and cathode materials of construction, ; particularly the effect of various grades of graphite as anode material. The ; effect of additives to the electrolyte (including potassium, aluminum, calcium, ; vanadium, nickel, Inconel, water, and sulfate ion) on boron yield and

George T. Miller

1959-01-01

248

Boron in the Environment  

Microsoft Academic Search

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

JEFFREY L. PARKS; MARC EDWARDS

2005-01-01

249

Accumulation and loss of arsenic and boron, alone and in combination, in mallard ducks  

SciTech Connect

Arsenic and boron are common in the environment, and wildlife can be exposed to toxic concentrations through both natural and human-influenced processes. The authors exposed adult male mallard ducks to dietary concentrations of 300 ppm arsenic as sodium arsenate, 1,600 ppm boron as boric acid, or both and estimated the tissue accumulation and loss rates when the ducks were returned to uncontaminated food. Both elements were accumulated rapidly; equilibrium levels were reached for arsenic in 10 to 30 d and for boron in 2 to 15 d. Accumulation of each element was slowed by the presence of the other in the diet. Boron was eliminated by mallards very rapidly, with few detectable residues {ge}1 d after removal of boron from the diet; arsenic was also rapidly lost with half-lives of 1 to 3 d (half-lives were not constant throughout the loss period). Arsenic loss rate was not affected by the presence of boron. Arsenic accumulated to the highest level in liver tissue, with blood and brain levels lower; concentrations in the liver and blood were proportional but affected by the presence of boron. Boron concentrations were highest in the blood, followed by the brain and liver; concentrations in the liver and blood were proportional but affected by the presence of boron. Boron concentrations were highest in the blood, followed by the brain and liver; concentrations in the blood and liver were proportional.

Pendleton, G.W.; Whitworth, M.R.; Olsen, G.H. [National Biological Service, Laurel, MD (United States). Patuxent Environmental Science Center

1995-08-01

250

Beyond phthalates: gas phase concentrations and modeled gas/particle distribution of modern plasticizers.  

PubMed

The ongoing health debate about polymer plasticizers based on the esters of phthalic acid, especially di(2-ethylhexyl) phthalate (DEHP), has caused a trend towards using phthalates of lower volatility such as diisononyl phthalate (DINP) and towards other acid esters, such as adipates, terephthalates, citrates, etc. Probably the most important of these so-called "alternative" plasticizers is diisononyl cyclohexane-1,2-dicarboxylate (DINCH). In the indoor environment, the continuously growing market share of this compound since its launch in 2002 is inter alia apparent from the increasing concentration of DINCH in settled house dust. From the epidemiological point of view there is considerable interest in identifying how semi-volatile organic compounds (SVOCs) distribute in the indoor environment, especially in air, airborne particles and sedimented house dust. This, however, requires reliable experimental concentration data for the different media and good measurements or estimates of their physical and chemical properties. This paper reports on air concentrations for DINP, DINCH, diisobutyl phthalate (DIBP), diisobutyl adipate (DIBA), diisobutyl succinate (DIBS) and diisobutyl glutarate (DIBG) from emission studies in the Field and Laboratory Emission Cell (FLEC). For DINP and DINCH it took about 50 days to reach the steady-state value: for four months no decay in the concentration could be observed. Moreover, vapor pressures p(0) and octanol-air partitioning coefficients K(OA) were obtained for 37 phthalate and non-phthalate plasticizers from two different algorithms: EPI Suite and SPARC. It is shown that calculated gas/particle partition coefficients K(p) and fractions can widely differ due to the uncertainty in the predicted p(0) and K(OA) values. For most of the investigated compounds reliable experimental vapor pressures are not available. Rough estimates can be obtained from the measured emission rate of the pure compound in a microchamber as is shown for di-n-butyl phthalate (DnBP), di(2-ethylhexyl) adipate(DEHA), tri(octyl) trimellitate (TOTM) and DEHP. PMID:21764421

Schossler, Patrícia; Schripp, Tobias; Salthammer, Tunga; Bahadir, Müfit

2011-07-18

251

Optimal reconstruction of concentrations, gradients and reaction rates from particle distributions.  

PubMed

Random walk particle tracking methodologies to simulate solute transport of conservative species constitute an attractive alternative for their computational efficiency and absence of numerical dispersion. Yet, problems stemming from the reconstruction of concentrations from particle distributions have typically prevented its use in reactive transport problems. The numerical problem mainly arises from the need to first reconstruct the concentrations of species/components from a discrete number of particles, which is an error prone process, and then computing a spatial functional of the concentrations and/or its derivatives (either spatial or temporal). Errors are then propagated, so that common strategies to reconstruct this functional require an unfeasible amount of particles when dealing with nonlinear reactive transport problems. In this context, this article presents a methodology to directly reconstruct this functional based on kernel density estimators. The methodology mitigates the error propagation in the evaluation of the functional by avoiding the prior estimation of the actual concentrations of species. The multivariate kernel associated with the corresponding functional depends on the size of the support volume, which defines the area over which a given particle can influence the functional. The shape of the kernel functions and the size of the support volume determines the degree of smoothing, which is optimized to obtain the best unbiased predictor of the functional using an iterative plug-in support volume selector. We applied the methodology to directly reconstruct the reaction rates of a precipitation/dissolution problem involving the mixing of two different waters carrying two aqueous species in chemical equilibrium and moving through a randomly heterogeneous porous medium. PMID:20627365

Fernàndez-Garcia, D; Sanchez-Vila, X

2010-05-19

252

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

253

Magnetron sputtered boron films  

DOEpatents

A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

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

1998-01-01

254

Metal concentrations and distribution in the household, stairs and entryway dust of some Egyptian homes  

NASA Astrophysics Data System (ADS)

Household, stairs and entryway dust samples were collected from 16 houses distributed across Greater Cairo by using vacuum cleaner and sweeping methods during summer season of 2009. Lead (Pb), nickel (Ni), cadmium (Cd), aluminum (Al), iron (Fe), zinc (Zn), cobalt (Co), chromium (Cr) and copper (Cu) were measured in different dust particle sizes: <38 ?m, >38-45 ?m and >45-63 ?m. The highest average concentrations of Pb, Ni, Cd, Co, Cu, and Cr in different particle sizes were found in entryway followed by household and stairs. Al, Fe and Zn concentrations followed the pattern of entryway > stairs > household. Pb, Ni, Cd, Zn, Co and Cr were found in significantly (p < 0.01) higher concentrations in dust of the small particle size (<38 ?m), whereas Al, Fe and Cu were detected in significantly (p < 0.01) higher concentrations in dust of the large particle size (>45-63 ?m). The average concentrations of the individual metals in dust of the small particle size (<38 ?m) were 268, 196.4 and 254.49 ?g gm-1 for Pb, 49.6, 43.5 and 46.66 ?g gm-1 for Ni, 2.86, 2.15 and 2.71 ?g gm-1 for Cd, 4340, 3796 and 2602 ?g gm-1 for Al, 2860, 2200 and 2004 ?g gm-1 for Fe, 209.25, 152.3 and 103.26 ?g gm-1 for Zn, 4.1, 2.88 and 1.96 ?g gm-1 for Co, 85.99, 74.06 and 83.17 ?g gm-1 for Cr and 168.2, 156.5 and 122.02 ?g gm-1 for Cu in entryway, stairs and household, respectively. The mean concentrations of Cu and Pb in the entryway, stairs and household dust exceeded the maximum permissible limit 100 ?g gm-1 for Cu and Pb in soil. The highest concentrations of Pb, Cd, Co and Ni were found in urban areas, Al and Fe in the residential areas, and Cu, Zn and Cr in the residential near to industrial area. Significant positive correlation (p < 0.001) were found between the metal concentrations in household and entryway dust, indicating that the metals in household dust may be derived from outdoor sources in addition to dust generated within the house itself. The contribution of anthropogenic sources, especially traffic emission, to metal levels in household, entryway and stairs dust was reflected by the high values of enrichment factors for Pb, Cd, Zn and Cu and Ni and Cr in fine dust particle compared to the average crustal composition. Insignificant positive correlation coefficients were found between the concentrations of Pb and other metals in household dust. However, the correlation coefficients between the concentrations of Cd, Ni, Cr, Cu, Zn and Fe were statistically significant.

Hassan, Salwa Kamal Mohamed

2012-07-01

255

Microwave sintering of boron carbide  

DOEpatents

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.

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

1988-06-10

256

Electrochemical oxidation of electrodialysed reverse osmosis concentrate on Ti/Pt-IrO2, Ti/SnO2-Sb and boron-doped diamond electrodes.  

PubMed

Reverse osmosis concentrate from wastewater reclamation contains biorefractory trace organic contaminants that may pose environmental or health hazard. Due to its high conductivity, electrochemical oxidation of brine requires low voltage which is energetically favourable. However, the presence of chloride ions may lead to the formation of chlorinated by-products, which are likely to exert an increased toxicity and persistence to further oxidation than their non-chlorinated analogues. Here, the performance of Ti/Pt-IrO(2), Ti/SnO(2)-Sb and Si/BDD anodes was evaluated for the electrochemical oxidation of ROC in the presence of chloride, nitrate or sulfate ions (0.05 M sodium salts). In order to investigate the electrooxidation of ROC with nitrate and sulfate ions as dominant ion mediators, chloride ion concentration was decreased 10 times by electrodialytic pretreatment. The highest Coulombic efficiency for chemical oxygen demand (COD) removal was observed in the presence of high chloride ions concentration for all anodes tested (8.3-15.9%). Electrooxidation of the electrodialysed concentrate at Ti/SnO(2)-Sb and Ti/Pt-IrO(2) electrodes exhibited low dissolved organic carbon (DOC) (i.e. 23 and 12%, respectively) and COD removal (i.e. 37-43 and 6-22%, respectively), indicating that for these electrodes chlorine-mediated oxidation was the main oxidation mechanism, particularly in the latter case. In contrast, DOC removal for the electrodialysed concentrate stream was enhanced at Si/BDD anode in the presence of SO(4)(2-) (i.e. 51%) compared to NO(3)(2-) electrolyte (i.e. 41%), likely due to the contribution of SO(4)(·-) and S(2)O(8)(2-) species to the oxidative degradation. Furthermore, decreased concentration of chloride ions lead to a lower formation of haloacetic acids and trihalomethanes at all three electrodes tested. PMID:23137830

Bagastyo, Arseto Y; Batstone, Damien J; Rabaey, Korneel; Radjenovic, Jelena

2012-10-17

257

Temperature and concentration distribution of H2 and H atoms in hot-filament chemical-vapor deposition of diamond  

NASA Astrophysics Data System (ADS)

The temperature and concentration distributions of hydrogen in a hot-filament chemical-vapor deposition reactor of diamond have been measured simultaneously by coherent anti-Stokes Raman scattering (CARS). The bright background from the filaments was rejected by using CARS and gating on the detector as well as spatial filtering. The CARS spectra provided direct and accurate measurements of the H2 temperature and concentration distributions. The concentration distribution of atomic hydrogen was also determined by assuming a constant pressure condition and equilibrium between translational and rotational degrees of freedom in the system. It was found that the H-atom distribution departed substantially from the thermal equilibrium prediction except very near the filament; however, a diffusion-controlled model predicted the slope of this distribution throughout the measured region.

Chen, Kuei-Hsien; Chuang, Mei-Chen; Penney, Murray C.; Banholzer, William F.

1992-02-01

258

Indoor radon concentration data: Its geographic and geologic distribution, an example from the Capital District, NY  

SciTech Connect

Most studies of the geographic distribution of indoor radon levels are plotted by county or ZIP code. This method is used for the radon potential maps produced by the U.S. Environmental Protection Agency (EPA) and the New York State Department of Health (NYSDOH). The basis for the mapping is the mean or median indoor radon count for all the data provided by NYSDOH within each geographic area. While testing the indoor radon analyses provided to the authors by CMT Independent Laboratories, we discovered data that deviated markedly from the EPA and NYSDOH means for the Capital District of New York (Albany and surrounding counties). Their screening indoor radon average concentrations in pCi/L, indicate low potential for Schenectady (3.0), Saratoga (3.2), and Albany (3.7) counties; and moderate potential for Rensselaer (6.4) and Columbia (7.0) counties. Our database of over 3,000 analyses contains over 800 records of indoor radon counts above 4 pCi/L (14-47% of each county`s analyses), many high enough to be rated as a serious health hazard. In order to obtain greater precision of information, the authors plotted their indoor radon data by street address using MapInfo, a geographic Information System (GIS), and StreetInfo, MapInfo`s TIGER address database. We compared the geographic distribution of our data to both the Bedrock Geology and Surficial Geology Maps of New York State. The results show a striking relationship of radon concentrations to bedrock, faults and permeability of surficial material. Data being compiled and mapped by street address by the NYSDOH in Erie County in western New York, confirm our results.

Thomas, J.J. [Skidmore College, Saratoga Springs, NY (United States); Overeynder, H.M. [C.E.S., Gabon (Central African Republic); Thomas, B.R. [CMT Independent Laboratories, Clifton Park, NY (United States)

1995-09-01

259

LISST-WING: A New Laser Diffraction Instrument for Cloud Size Distribution and Concentration Research  

NASA Astrophysics Data System (ADS)

We describe the technology and first in-situ measurements in clouds from a laser diffraction instrument, LISST-WING. The instrument was developed as an SBIR project funded by ONR. Laser diffraction techniques offer the advantage of near-instant measurement of size spectra and concentration as it is based on multi-angle scattering of laser light from an ensemble of droplets contained in a 1 cm diameter, 15 cm long beam. The multi-angle scattering is inverted to obtain the size distribution, which produces the concentration or liquid water content from its sum. The size bins of this device are equally spaced in log(diameter), unlike prior technologies. The large volume of particles sensed per measurement (45 litres/sec at 60 knots) enables stable statistics. A size range from 2 micron to 400 micron is covered by the present instrument. The data are stored on board and downloaded at convenience. In summer 2005 the prototype was test-flown at the CIRPAS facility in Marina, California. High temporal resolution data were obtained. In this paper, these data will be described and compared with data where available from prior sensors installed on the CIRPAS research aircraft.

Agrawal, Y. C.; Jonsson, H.; Buzorius, G.

2005-12-01

260

The systematics of boron abundances in young volcanic rocks  

Microsoft Academic Search

Boron behaves as a highly incompatible trace element in oceanic settings, while in arcs it shows unique systematics indicative of fluid-rock interactions. Boron analyses conducted on well-characterized mid-ocean ridge basalt (MORB) suites show that B approximates K most closely in its solid\\/ melt distribution behavior, with inferred bulk distribution coefficients of 0.004-0.009 during melting in the mantle and up to

Jeffrey G. Ryan; Charles H. Langmuir

1993-01-01

261

Concentration and distribution of heavy metals in two Andisols of the Azuay Andes (Ecuador)  

NASA Astrophysics Data System (ADS)

At present many governmental and environmental bureaus are interested in establishing reliable soil quality criteria for heavy metals to enable the detection of polluted sites. To evaluate the variation of heavy metal natural concentration and to assess heavy metal contamination in soils, it is necessary to survey heavy metal baseline levels in order to understand their migration and distribution during pedogenesis. Many nationwide projects report elemental baseline values in soils. Baseline levels of heavy metals in soils have also been determined at local scales. Data is scarce on qualitative and quantitative trace elements content of Ecuatorian soils. The soils in the Azuay Andes (S of Ecuador) are thought to be generally non-contaminated. The objective of this study is to determine and evaluate the natural concentrations and distribution of seven heavy metals (Cd, Co, Cr, Cu, Ni, Pb and Zn) in Andisol of Azuay Andes. Soil samples were grounded in an agate mill prior to pseudototal heavy metal analysis. Cadmium, Co, Cr, Cu, Ni, Pb and Zn were determined by a masses spectrometer (MS-ICP) after aqua regia extraction according to ISO standard procedures. Soil particle size distribution, organic carbon, electrical conductivity and pH have been previously determined. Andisols are dominated by amorphous aluminium silicates and Al-organic complexes. The soils of volcanic area usually have an Ah-Bh-Bhs/Bw-C horizon sequence. The Ah horizon is dark-coloured and normally very high in organic matter, ranging from 6.4 to 15.2 %. A strong rise in pH upon addition of a fluoride solution is used to signal the presence of allophane. The pH usually rises to 10.5 bellow 20 cm. The range of total soil values in mgkg-1 is as follows: Cd (0.03-0.3), Co (0.8-5), Cr (7-15), Cu (9-25), Ni (2-4), Pb (11-41) and Zn (12-37). All heavy metal contents, except for Cd, are strongly correlated with pH. For the pseudototal fraction, there was significant difference between the soil horizons in regards to complex profile development.

Bech, Jaume; Roca, Núria; Ugalde, Sandra; Tonon, Luis; Larriva, Giovani

2013-04-01

262

Concentration and distribution of sixty-one elements in coals from DPR Korea  

USGS Publications Warehouse

Fifty coal samples (28 anthracite and 22 lignites) were collected from both main and small coal mines in DPR Korea prioritized by resource distribution and coal production. The concentrations of 61 elements in 50 coal samples were determined by several multielement and element-specific techniques, including inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS), ion chromatogram (IC), cold-vapor atomic absorption spectrometry (CV-AAS), and hydride generation atomic absorption spectrometry (HGAAS). The ranges, arithmetic means and geometric means of concentrations of these elements are presented. A comparison with crustal abundances (Clarke values) shows that some potentially hazardous elements in the coals of DPR Korea are highly enriched Li, B, S, Cl, Zn, As, Se, Cd, Sn, Sb, W, Te, Hg, Ag, Pb, and La, Ce, Dy, Tm, Ge, Mo, Cs, Tl, Bi, Th and U are moderately enriched. A comparison of ranges and means of elemental concentrations in DPR Korea, Chinese, and world coals shows the ranges of most elements in DPR Korea coals are very close to the ranges of world coals. Arithmetic means of most elements in DPR Korea coals are close to that of American coals. Most elements arithmetic means are higher in Jurassic and Paleogene coals than coals of other ages. In DPR Korea coals, only seven elements in early Permian coals are higher than other periods: Li, Zn, Se, Cd, Hg, Pb, and Bi. Only five elements B, As, Sr, Mo, W in Neogene coals have arithmetic means higher than others. SiO2 and Al2O 3 in ashes are more than 70% except six samples. The correlation between ash yields and major elements from high to low is in the order of Si>Al>Ti>K>Mg>Fe>Na>Ca>P>S. Most elements have high positive correlation with ash (r>0.5) and show high inorganic affinity. ?? 2005 Elsevier Ltd. All rights reserved.

Hu, J.; Zheng, B.; Finkelman, R. B.; Wang, B.; Wang, M.; Li, S.; Wu, D.

2006-01-01

263

'The measurement of thermal neutron flux depression for determining the concentration of boron in blood'--suggestions as to further development of the method.  

PubMed

Suggestions about determining the concentration of 10B in blood via the thermal neutron flux depression measurement (NFDM) are made. The use of a measuring set-up consisting of a 252Cf neutron source, polyethylene moderator and a slim BF3 counter surrounded by an annular sample is examined. It is shown experimentally that using 6 ml samples and the source emitting 1.4 x 10(7) neutrons s(-1), one can determine the concentration of 10B in water at the level of 10 ppm with a statistical precision of 10% in about 20 min. Monte Carlo simulations performed with the use of MCNP-4C code revealed a potential for further improvements of the NFDM technique both in respect of the sample volume and counting period. PMID:16204865

Bolewski, A; Ciechanowski, M; Dydejczyk, A; Kreft, A

2005-10-04

264

Boronated Unnatural Cyclic Amino Acids as Potential Delivery Agents for Neutron Capture Therapy  

PubMed Central

Boron delivery characteristics of cis and trans isomers of a boronated unnatural amino acid, 1-amino-3-boronocyclopentanecarboxylic acid (ABCPC) were tested in B16 mouse model for human melanoma. Both ABCPC isomers delivered comparable boron to B16 melanoma tumor cells as L-p-boronophenylalanine (BPA). Secondary ion mass spectrometry (SIMS) analysis revealed the presence of boron throughout the tumor from these compounds, and a near homogeneous distribution between the nucleus and cytoplasm of B16 cells grown in vitro. These encouraging observations support further studies of these new boron carriers in BNCT.

Kabalka, George W.; Shaikh, Aarif L.; Barth, Rolf F.; Huo, Tianyao; Yang, Weilian; Gordnier, Pamela M.; Chandra, Subhash

2011-01-01

265

Novel approach for tomographic reconstruction of gas concentration distributions in air: Use of smooth basis functions and simulated annealing  

Microsoft Academic Search

Optical remote sensing and iterative computed tomography (CT) can be applied to measure the spatial distribution of gaseous pollutant concentrations. We conducted chamber experiments to test this combination of techniques using an open path Fourier transform infrared spectrometer (OP-FTIR) and a standard algebraic reconstruction technique (ART). Although ART converged to solutions that showed excellent agreement with the measured ray-integral concentrations,

A. C. Drescher; A. J. Gadgil; P. N. Price; W. W. Nazaroff

1996-01-01

266

Prompt gamma activation analysis of boron in reference materials using diffracted polychromatic neutron beam  

NASA Astrophysics Data System (ADS)

Boron concentrations were analyzed for standard reference materials by prompt gamma activation analysis (PGAA). The measurements were performed at the SNU-KAERI PGAA facility installed at Hanaro, the research reactor of Korea Atomic Energy Research Institute (KAERI). The facility uses a diffracted polychromatic beam with a neutron flux of 7.9×107 n/cm2s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 ?g boron. The sensitivity of 2131 cps/mg-B was obtained from the linearity of the boron peak count rate versus the boron mass. The detection limit for boron was estimated to be 67 ng from an empty sample bag spectrum for a counting time of 10,000 s. The measured boron concentrations for standard reference materials showed good consistency with the certified or information values.

Byun, S. H.; Sun, G. M.; Choi, H. D.

2004-01-01

267

Drinking water health advisory for boron  

Microsoft Academic Search

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

Cantilli

1991-01-01

268

Mapping boron in silicon solar cells using electron energy-loss spectroscopy  

NASA Astrophysics Data System (ADS)

Electron energy-loss spectroscopy (EELS) is used to study the B distribution in a p-i-n layered solar cell structure. The boron concentration in the p-doped Si layer is expected to be ~1021 cm-3 and should not exceed 1017 cm-3 in the neighbouring intrinsic layer. We show that B concentrations as low as 3×l020 cm-3 (0.6 at. %) can be measured using EELS. Our measurements are in close agreement with real space ab-initio multiple scattering calculations and secondary ion mass spectrometry measurements.

Duchamp, M.; Boothroyd, C. B.; Kovács, A.; Kadkhodazadeh, S.; Kasama, T.; Moreno, M. S.; Van Aken, B. B.; Barnes, J.-P.; Veillerot, M.; Newcomb, S. B.; Dunin-Borkowski, R. E.

2011-11-01

269

Biological aerosol particle concentrations and size distributions measured in pristine tropical rainforest air during AMAZE-08  

NASA Astrophysics Data System (ADS)

As a part of the AMAZE-08 campaign during the wet season in the rainforest of Central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS) was operated for continuous measurements of fluorescent biological aerosol particles (FBAP). In the coarse particle size range (> 1 ?m) the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 104 m-3 (4.0-13.2 × 104 m-3) and 0.72 ?g m-3 (0.42-1.19 ?g mm-3), respectively, accounting for 24% (11-41%) of total particle number and 47% (25-65%) of total particle mass. During the five-week campaign in February-March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 ?m, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM), light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP) mode between 0.5 and 1.0 ?m was also observed by SEM, but exhibited little fluorescence and no fungal staining. This mode consisted of single bacterial cells, brochosomes and various fragments of biological material. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF) techniques provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles. We also show that primary biological particles, fungal spores in particular, are key fractions of supermicron aerosol in the Amazon and that, especially when coated by mixed inorganic material, could contribute significantly to hydrological cycling in such regions of the globe.

Huffman, J. A.; Sinha, B.; Garland, R. M.; Snee-Pollmann, A.; Gunthe, S. S.; Artaxo, P.; Martin, S. T.; Andreae, M. O.; Pöschl, U.

2012-09-01

270

The investigation of parameters affecting boron removal by electrocoagulation method  

Microsoft Academic Search

Boron removal from wastewaters by electrocoagulation using aluminum electrode material was investigated in this paper. Several working parameters, such as pH, current density, boron concentration and type and concentration of supporting electrolyte were studied in an attempt to achieve a higher removal capacity. The experiments were carried out by keeping the pH of solution constant and optimum pH of solution

A. Erdem Yilmaz; Recep Boncukcuo?lu; M. Muhtar Kocakerim; Bülent Keskinler

2005-01-01

271

Boron in the major UK rivers entering the North Sea  

Microsoft Academic Search

Boron in the major UK rivers entering the North Sea is predominantly in dissolved form and concentrations show large variations in time and space. The time-dependent feature relates to seasonal patterns linked to flow. Boron concentrations are well described by a power relationship of the type [B]=a?flowb, where a and b are constants. In this equation, the a term varies

Colin Neal; Kay K Fox; Martin Harrow; Margaret Neal

1998-01-01

272

Boron Enrichment in Martian Clay  

PubMed Central

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

Nagashima, Kazuhide; Freeland, Stephen J.

2013-01-01

273

Boron enrichment in martian clay.  

PubMed

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

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

2013-06-06

274

Estimating the spatial distribution of dredged material disposed of at sea using particle-size distributions and metal concentrations.  

PubMed

We present a method to estimate the spatial distribution of dredged material disposed of at sea. Using both dredged sediments and samples of sea-bed sediment from near the Rame Head disposal site, Plymouth, UK, we applied entropy analysis to the <63 microm sediment fraction and combined the results with the trace metal data in the same fraction, to form a series of groups. We interpret the distribution of sediments in one group (F1) to approximate the distribution of material affected by the disposal site. This distribution includes locations close to the disposal site, and also locations <4 km to the SE and SW, <6 km to the NW and <2 km to the N. This approach demonstrates the feasibility of using trace metal analysis of particular grain size fractions to reduce uncertainty in interpreting the spatial distribution of impacts of dredge disposal. PMID:19464703

Okada, Tomonari; Larcombe, Piers; Mason, Claire

2009-05-22

275

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

276

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

277

Direct current sputtering of boron from boron/carbon 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, J.R.; Manos, D.; Nartowitz, E.

1993-12-31

278

Carbon and metal concentrations, size distributions and fluxes in major rivers of the Amazon basin  

NASA Astrophysics Data System (ADS)

The chemical composition of the Amazon River results from the mixing of two water types: black water and white water. On-site fractionation by sequential tangential ultrafiltration (STUF) was used to differentiate transported organic carbon and to determine the distribution and association of major and trace elements with different size fraction of the organic carbon (OC). Several sampling campaigns (1994-1996) allow a monthly quantification of particulate (OCP, MeP), colloidal (OCC, MeC) and dissolved (OCD, MeD) organic carbon and metal ions inputs. In white rivers the OC is mainly concentrated in the low molecular weight fraction (OCD < 5000 D) while in black rivers most of the OC is in the heavier molecular weight fractions (OCP and OCC > 5 kDa). For Mg, Ca and K, 50% of the total amount of each element is found in fraction MeD while 15% and 35% are found in fractions MeC and MeP, respectively. Al and Fe are in the particulate fraction at 99% of the total metal concentration for all river samples. This work emphasizes the coagulation processes and the sink for elements in the mixing zone. These physicochemical transformations of the organic matter vary seasonally. The changes happen during the transition periods: before high-level waters and before low-level waters. By way of flux measurement, a seasonal carbon loss was observed. The estimated annual organic carbon flux of the Amazon at Òbidos is 28 × 106 t. At the same time, an average of 9 × 106 t of organic carbon per year is retained in the reach between Manaus and Òbidos, probably via coagulation processes.

Benedetti, Marc F.; Mounier, Stephane; Filizola, Naziano; Benaim, Jean; Seyler, Patrick

2003-05-01

279

Behavior of Boron Isotopes During Chemical Weathering: a Global Approach  

NASA Astrophysics Data System (ADS)

Boron has two isotopes (10B and 11B) that fractionate largely during Earth surface processes. The major fractionating step takes place during low temperature water-rock interactions. Up to 20-30 \\permil difference in ? 11B units are shown to occur during the adsorption of boron onto surfaces or its precipitation into solids. Light boron has a much greater affinity for neoformed solids while the residual solution is enriched in heavy boron. For example, seawater has a boron isotopic composition of 40 \\permil, mainly due to the preferential removal of 10B during oceanic seafloor weathering, adsorption onto fluvial sediments and chemical weathering reactions occurring in soils. The high sensitivity of boron isotopes fractionation to water rock interactions make it a valuable tool to constrain chemical weathering processes. To have a global picture of the behavior of boron isotopes during chemical weathering of rocks at the surface of the continents, we analyzed the largest rivers for both the dissolved and suspended load. Dissolved boron isotopic compositions were published earlier ([Lemarchand et al., 2000]) and we here focus on the results for the suspended load and for the bottom sands. Boron clearly appears as a mobile element when its abundance in suspended sediments is normalized to upper continental material. Boron depletion in suspended solids is climate dependent, with higher depletion is warm climates. On average, more than 50 % of boron is transported to the ocean in a solid form. While the dissolved load of boron is clearly enriched in 11B (0 \\permil) with respect to the mean upper continental crust (-10 \\permil), isotopic composition of the suspended load of major rivers does not differ significantly from that of the continental crust. This result indicates that suspended material is not significantly fractionated with respect to the continental crust by chemical weathering processes or that the mass budget of boron partitioning between solids and water does not allow the residual solids to be significantly different from bedrock. This is supported by a Rayleigh distillation model. Our boron data, both in concentration and isotopic composition, give strong support to the idea that shale erosion is a major source of suspended sediments in large river system, making thus boron isotopes a good tracer of intra-continental recycling. Lemarchand et al., 2000, Nature, vol 408, pp 951-954.

Gaillardet, J.; Chetelat, B.

2004-12-01

280

1H and 10B NMR and MRI investigation of boron- and gadolinium–boron compounds in boron neutron capture therapy  

Microsoft Academic Search

10B molecular compounds suitable for Boron Neutron Capture Therapy (BNCT) are tagged with a Gd(III) paramagnetic ion. The newly synthesized molecule, Gd-BPA, is investigated as contrast agent in Magnetic Resonance Imaging (MRI) with the final aim of mapping the boron distribution in tissues. Preliminary Nuclear Magnetic Resonance (NMR) measurements, which include 1H and 10B relaxometry in animal tissues, proton relaxivity

M. Bonora; M. Corti; F. Borsa; S. Bortolussi; N. Protti; D. Santoro; S. Stella; S. Altieri; C. Zonta; A. M. Clerici; L. Cansolino; C. Ferrari; P. Dionigi; A. Porta; G. Zanoni; G. Vidari

2011-01-01

281

Prediction of Late-Time Concentration Tailing Through Characterization of Hydrofacies Distributions  

NASA Astrophysics Data System (ADS)

Anomalous (non-Fickian) diffusion is often manifested in extra mass in the late-time tail of the breakthrough curve (BTC). Current non-local techniques, including the multi-rate mass transfer method (MRMT) and the continuous time random walk (CTRW) method, are a posteriori fitting procedures that assign an appropriate memory function or a transition time distribution function to account for the trapping of solute particles in relatively immobile domains. The MRMT and CTRW are functionally equivalent, but the MRMT method allows a straightforward, a priori construction of the memory function based on readily available information about the statistics of the immobile zone geometry. We explore the quantitative relationship between the memory function and aquitard material heterogeneity using Monte Carlo simulations of the regional-scale alluvial aquifer system at the Lawrence Livermore National Laboratory site. Particle tracking simulations show that the shape of the late-time BTC depends on the thickness and the associated volume fractions of immobile water in "blocks" of fine-grained material. The ensemble solute concentration at later time can be very accurately predicted using a small number of exponential functions with rates dictated by aquitard thicknesses. Specifically, if the volume fraction of immobile layer thicknesses has a power-law probability distribution function (pdf), then a power-law BTC late tail will be guaranteed. When the volume fraction of immobile blocks has an exponential pdf, the late-time BTC will have a transition from power-law to exponential decay. The MRMT solutions are easily generated and accurately predict the later BTC tails. Since the residence time dictated by diffusive motion in the silt and clay layers embedded in typical natural media far exceeds the residence time in a laboratory column, we anticipate that upscaling from lab studies is irrelevant in most cases. The observed relationship between the BTC late tail and the aquitard property implies that 1) it is possible to build the memory function given information of the distribution of fine-grained units, and 2) we may predict the general behavior of late-time, non-Fickian MRMT or CTRW transport by gleaning information from boring logs or outcrops.

Zhang, Y.; Benson, D. A.

2006-12-01

282

Minerals Yearbook 1989: Boron.  

National Technical Information Service (NTIS)

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 ...

P. A. Lyday

1990-01-01

283

Minerals Yearbook 1990: Boron.  

National Technical Information Service (NTIS)

U.S. production and sales of boron minerals and chemicals increased 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 ...

P. A. Lyday

1991-01-01

284

Minerals Yearbook, 1993: Boron.  

National Technical Information Service (NTIS)

U.S. production and sales of boron minerals and chemicals increased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to borosilicate glass, textile-grade glass fibers, and agriculture. California was...

P. A. Lyday

1994-01-01

285

Controlling the electron energy distribution function of electron beam generated plasmas with molecular gas concentration: I. Experimental results  

NASA Astrophysics Data System (ADS)

This paper, the first in a series of two, presents experimental results demonstrating the control of electron and ion energy distribution functions in electron beam generated processing plasmas by adding trace concentrations of N2 to an Ar background. Measurements of the electron energy distribution function, f0(E), are performed using a Langmuir probe while measurements of the Ar ion energy distribution function are performed using an energy-resolved mass spectrometer. The experimental results agree with modeling results, described in part II of this work, which indicate that inelastic electron collisions with nitrogen molecules provide an energy sink that can be exploited to control the electron energy distribution function.

Boris, D. R.; Petrov, G. M.; Lock, E. H.; Petrova, Tz B.; Fernsler, R. F.; Walton, S. G.

2013-12-01

286

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

287

Boron and Plants  

Microsoft Academic Search

\\u000a Boron is found naturally in the earth’s crust in the oxidized form as borax and colemanite, particularly in the oceans, sedimentary\\u000a rocks, coal, shale, and some soils. It is never found in the elemental form in nature possessing a complex chemistry similar\\u000a to that of silicon, with properties switching between metals and non-metals. Boron has become an important and strategic

Munir Ozturk; Serdal Sakcali; Salih Gucel; Huseyin Tombuloglu

288

Minerals Yearbook, 1988. Boron  

SciTech Connect

U.S. production and sales of boron minerals and chemicals decreased during the year. 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 report discusses the following: domestic data coverage; legislation and government programs; domestic production; comsumption and uses; prices; foreign trade; world capacity; world review--Argentina, Chile, France, Italy, Turkey, United Kingdom; Technology.

Lyday, P.A.

1988-01-01

289

Concentration and spatial distribution of lead in soil used for ammunition destruction.  

PubMed

Studies on heavy metal contamination in soils used for ammunition disposal and destruction are still emerging. The present study aimed to evaluate the contamination level and spatial distribution of lead in disposal and destruction areas. This site was used for ammunition disposal and destruction activities for 20 years. The ammunition destruction site (1,296 ha), a sampling system that followed a sampling grid (5 m × 5 m) with 30 points was adopted and samples were collected at the following five depths with a total of 150 samples. During the collection procedure, each sampling grid point was georeferenced using a topographic global positioning system. Data were validated through semivariogram and kriging models using Geostat software. The results demonstrated that the average lead value was 163 mg kg(-1), which was close to the investigation limit and the contamination levels were higher downstream than upstream. The results showed that there was lead contamination at the destruction site and that the contamination existed mainly at the surface layer depth. However, high lead concentrations were also found at deeper soil depths in the destruction area due to frequent detonations. According to the planimetry data, the areas that require intervention significantly decreased with increasing depths in the following order: 582.7 m(2) in the 0-20 cm layer; 194.6 m(2) in the 20-40 cm layer; 101.6 m(2) in the 40-60 cm layer; and 45.3 m(2) in the 60-80 cm layer. PMID:22903201

do Nascimento Guedes, Jair; do Amaral Sobrinho, Nelson Moura Brasil; Ceddia, Marcos Bacis; Vilella, André Luis Oliveira; Tolón-Becerra, Alfredo; Lastra-Bravo, Xavier Bolívar

2012-08-18

290

Distribution of blood and tissue concentrations in rats by inhalation exposure to 1,2-dichloroethane.  

PubMed

The compound 1,2-dichloroethane (DCE) is a ubiquitous environmental contaminant. The primary route of exposure of humans to DCE is inhalation of its vapor. The present investigation was undertaken to determine the distribution and accumulation of DCE in the blood, lung, liver, brain, kidney and abdominal fat of rats during and after inhalation exposure. Male rats were exposed to 160 ppm (v/v) of DCE vapor for 360 min and the concentrations of DCE in the blood and tissues during the inhalation exposure period and after the end of the exposure period were measured. DCE accumulation in the abdominal fat was much greater than that in the blood and other tissues. The information we obtained in this study is useful basic data pertaining to the pharmacokinetics of DCE and DCE-mediated carcinogenicity: Our results suggest that one of the factors involved in the induction of peritoneal tumors in rats exposed to DCE vapor by inhalation is DCE accumulation in the abdominal fat. PMID:23573923

Take, Makoto; Takanobu, Kenji; Takeuchi, Tetsuya; Haresaku, Mitsuru; Matsumoto, Michiharu; Nagano, Kasuke; Yamamoto, Seigo; Fukushima, Shoji

2013-01-01

291

Statistical approach for the source identification of boron in leachates from industrial landfills  

Microsoft Academic Search

Boron has been found in high concentrations in leachates from landfills located throughout Japan. However, the source(s) of\\u000a boron in the leachates, i.e., what kind of waste(s) releases this element into the leachate, has not been clarified. In this\\u000a study, boron concentrations in leachates from 48 industrial landfills were evaluated, in relation to the categories of waste\\u000a constituting the landfill

Jun Yoshinaga; Akiko Kida; Osami Nakasugi

2001-01-01

292

Retardation in the chemical-mechanical polish of the boron-doped polysilicon and silicon  

Microsoft Academic Search

This letter reports on the chemical-mechanical polishing (CMP) of boron-doped polysilicon and silicon. Successive polishing was carried out to investigate how the removal rate correlates to the boron concentration as a function of depth in the polysilicon and crystalline silicon. It is found that the removal of boron-doped samples is significantly retarded and strongly correlated with the doping concentration. To

Wen Luh Yang; Chih-Yuan Cheng; Ming-Shih Tsai; Don-Gey Liu; Ming-Sun Shieh

2000-01-01

293

Bor Madeninin Ah?ap Koruma Endüstrisinde De?erlendirilmesi Evaluation Boron Mine in Wood Protection Industry  

Microsoft Academic Search

Boron is the first element with five atomic number of tirth group in periodical system. It consist of two isotops, one having a mass number of 10, the other a mass number of 11. Boron is most common element in the soil, rock and water. Boron resource at high concentrations and economical is found plentiful in the arid, volcanic and

H. Sivrikaya

294

Effects of boron supplementation on bone mineral density and dietary, blood, and urinary calcium, phosphorus, magnesium, and boron in female athletes.  

PubMed Central

The effects of boron supplementation on blood and urinary minerals were studied in female college students--17 athletes and 11 sedentary controls--over a one-year period. The athletes had lower percent body fat and higher aerobic capacities than sedentary controls. Athletic subjects consumed more boron in their normal diets than sedentary subjects; all other dietary measures were similar between the two groups. The athletes showed a slight increase in bone mineral density, whereas the sedentary group showed a slight decrease. Serum phosphorus concentrations were lower in boron-supplemented subjects than in subjects receiving placebos, and were lower at the end of the study period than during baseline analysis. Activity depressed changes in serum phosphorus in boron-supplemented subjects. Serum magnesium concentrations were greatest in the sedentary controls whose diets were supplemented with boron, and increased with time in all subjects. A group x supplement interaction was observed with serum magnesium; exercise in boron-supplemented subjects lowered serum magnesium. In all subjects, calcium excretion increased over time; in boron-supplemented subjects, boron excretion increased over time. In all subjects, boron supplementation affected serum phosphorus and magnesium, and the excretion of urinary boron.

Meacham, S L; Taper, L J; Volpe, S L

1994-01-01

295

Boron as an Alternate Engine Fuel  

Microsoft Academic Search

Boron fuel is made up of the element boron. Boron as a chemical fuel will be a promising engine fuel in the future. Cars in which boron fuel simply burns will be true zero emission vehicles. Total world production of boron minerals was approximately 4,270,000 tons in 2000. Turkey has the largest boron sources in the world. It is estimated

M. Balat

2007-01-01

296

Quantitative subcellular imaging of boron compounds in individual mitotic and interphase human glioblastoma cells with imaging secondary ion mass spectrometry (SIMS).  

PubMed

Boron measurements at subcellular scale are essential in boron neutron capture therapy (BNCT) of cancer as the nuclear localization of boron-10 atoms can enhance the effectiveness of killing individual tumour cells. Since tumours contain a heterogeneous population of cells in interphase as well as in the M phase (mitotic division) of the cell cycle, it is important to evaluate the subcellular distribution of boron in both phases. In this work, the secondary ion mass spectrometry (SIMS) based imaging technique of ion microscopy was used to quantitatively image boron from two BNCT agents, clinically used p-boronophenylalanine (BPA) and 3-[4-(o-carboran-1-yl)butyl]thymidine (N4), in mitotic metaphase and interphase human glioblastoma T98G cells. N4 belongs to a class of experimental BNCT agents, designated 3-carboranyl thymidine analogues (3CTAs), which presumably accumulate selectively in cancer cells due to a process referred to as kinase-mediated trapping (KMT). The cells were exposed to BPA for 1 h and N4 for 2 h. A CAMECA IMS-3f SIMS ion microscope instrument capable of producing isotopic images with 500 nm spatial resolution was used in the study. Observations were made in cryogenically prepared fast frozen, and freeze-fractured, freeze-dried cells. Three discernible subcellular regions were studied: the nucleus, a characteristic mitochondria-rich perinuclear cytoplasmic region, and the remaining cytoplasm in interphase T98G cells. In metaphase cells, the chromosomes and the cytoplasm were studied for boron localization. Intracellular concentrations of potassium and sodium also were measured in each cell in which the subcellular boron concentrations were imaged. Since the healthy cells maintain a K/Na ratio of approximately 10 due to the presence of Na-K-ATPase in the plasma membrane of mammalian cells, these measurements provided validation for cryogenic sample preparation and indicated the analysis healthy, well preserved cells. The BPA-treated interphase cells revealed significantly lower concentrations of boron in the perinuclear mitochondria-rich cytoplasmic region as compared to the remaining cytoplasm and the nucleus, which were not significantly different from each other. In contrast, the BPA-treated metaphase cells revealed significantly lower concentration of boron in their chromosomes than cytoplasm. In addition, the cytoplasm of metaphase cells contained significantly less boron than the cytoplasm of interphase cells. These observations provide valuable information on the reduced uptake of boron from BPA in mitotic cells for BPA-mediated BNCT. SIMS observations on N4 revealed that boron was distributed throughout the interphase and mitotic cells, including the chromosomes. The presence of boron in chromosomes of metaphase cells treated with N4 is indicative of a possible incorporation of this thymidine analogue into DNA. The 3-D SIMS imaging approach for the analysis of mitotic cells shown in this work should be equally feasible to the evaluation of other BNCT agents. PMID:18173648

Chandra, S; Tjarks, W; Lorey, D R; Barth, R F

2008-01-01

297

Primary Accretion and Turbulent Cascades: Scale-Dependence of Particle Concentration Multiplier Probability Distribution Functions  

NASA Astrophysics Data System (ADS)

Primitive bodies with 10s-100s of km diameter (or even larger) may form directly from small nebula constituents, bypassing the step-by-step “incremental growth” that faces a variety of barriers at cm, m, and even 1-10km sizes. In the scenario of Cuzzi et al (Icarus 2010 and LPSC 2012; see also Chambers Icarus 2010) the immediate precursors of 10-100km diameter asteroid formation are dense clumps of chondrule-(mm-) size objects. These predictions utilize a so-called cascade model, which is popular in turbulence studies. One of its usual assumptions is that certain statistical properties of the process (the so-called multiplier pdfs p(m)) are scale-independent within a cascade of energy from large eddy scales to smaller scales. In similar analyses, Pan et al (2011 ApJ) found discrepancies with results of Cuzzi and coworkers; one possibility was that p(m) for particle concentration is not scale-independent. To assess the situation we have analyzed recent 3D direct numerical simulations of particles in turbulence covering a much wider range of scales than analyzed by either Cuzzi and coworkers or by Pan and coworkers (see Bec et al 2010, J. Flu. Mech 646, 527). We calculated p(m) at scales ranging from 45-1024? where ? is the Kolmogorov scale, for both particles with a range of stopping times spanning the optimum value, and for energy dissipation in the fluid. For comparison, the p(m) for dissipation have been observed to be scale-independent in atmospheric flows (at much larger Reynolds number) for scales of at least 30-3000?. We found that, in the numerical simulations, the multiplier distributions for both particle concentration and fluid dissipation are as expected at scales of tens of ?, but both become narrower and less intermittent at larger scales. This is consistent with observations of atmospheric flows showing scale independence to >3000? if scale-free behavior is established only after some number 10 of large-scale bifurcations (at scales perhaps 10x smaller than the largest scales in the flow), but become scale-free at smaller scales. Predictions of primitive body initial mass functions can now be redone using a slightly modified cascade.

Cuzzi, Jeffrey N.; Weston, B.; Shariff, K.

2013-10-01

298

Process for making boron nitride using sodium cyanide and boron  

DOEpatents

This a very simple process for making boron nitride by mixing sodium cyanide and boron phosphate and heating the mixture in an inert atmosphere until a reaction takes place. The product is a white powder of boron nitride that can be used in applications that require compounds that are stable at high temperatures and that exhibit high electrical resistance.

Bamberger, Carlos E. (Oak Ridge, TN)

1990-01-01

299

Estimates of microbial quality and concentration of copper in distributed drinking water are highly dependent on sampling strategy.  

PubMed

The numbers of bacteria generally increase in distributed water. Often household pipelines or water fittings (e.g., taps) represent the most critical location for microbial growth in water distribution systems. According to the European Union drinking water directive, there should not be abnormal changes in the colony counts in water. We used a pilot distribution system to study the effects of water stagnation on drinking water microbial quality, concentration of copper and formation of biofilms with two commonly used pipeline materials in households; copper and plastic (polyethylene). Water stagnation for more than 4h significantly increased both the copper concentration and the number of bacteria in water. Heterotrophic plate counts were six times higher in PE pipes and ten times higher in copper pipes after 16 h of stagnation than after only 40 min stagnation. The increase in the heterotrophic plate counts was linear with time in both copper and plastic pipelines. In the distribution system, bacteria originated mainly from biofilms, because in laboratory tests with water, there was only minor growth of bacteria after 16 h stagnation. Our study indicates that water stagnation in the distribution system clearly affects microbial numbers and the concentration of copper in water, and should be considered when planning the sampling strategy for drinking water quality control in distribution systems. PMID:17223387

Lehtola, Markku J; Miettinen, Ilkka T; Hirvonen, Arja; Vartiainen, Terttu; Martikainen, Pertti J

2007-01-16

300

Modeling the U.S. national distribution of waterborne pathogen concentrations with application to Cryptosporidium parvum  

Microsoft Academic Search

This paper provides a general statistical methodology for modeling environmental pathogen concentrations in natural waters. A hierarchical model of pathogen concentrations captures site and regional random effects as well as random laboratory recovery rates. Recovery rates were modeled by a generalized linear mixed model. Two classes of pathogen concentration models are differentiated according to their ultimate purpose: water quality prediction

Ciprian M. Crainiceanu; Jery R. Stedinger; David Ruppert; Christopher T. Behr

2003-01-01

301

Modeling the U.S. national distribution of waterborne pathogen concentrations with application to Cryptosporidium parvum  

Microsoft Academic Search

This paper provides a general statistical methodology for modeling environmental pathogen concentrations in natural waters. A hierarchical model of pathogen concentrations captures site and regional random effects as well as random laboratory recovery rates. Recovery rates were modeled by a Generalized Linear Mixed Model. Two classes of pathogen concentration models are differentiated according to their ultimate purpose: water quality prediction

Ciprian M. Crainiceanu; Jery R. Stedinger; David Ruppert; Christopher T. Behr

2003-01-01

302

Toxic elements at a disused mine district: Particle size distribution and total concentration in stream sediments and mine tailings.  

PubMed

Heavy metal and metalloid pollution at a disused pyrite mine was investigated. Five solid samples collected in the area (three stream sediments with different soil texture, a background soil sample and a mine tailing) were characterised by mineral and element composition, particle size distribution (by wet and dry sieving and laser diffraction) and total concentration by acid digestion (Mn, Zn, Cu, Pb, Hg, Cd, Sb and As). X-ray and element analyses denoted a common mineralogical and chemical composition of mainly quartz, clinochlore, muscovite, anorthite, and hematite. Particle size distributions of the five samples showed that stream sediments were characterised by larger percentage of sand range classes (2000-60 microm) while background sample and tailing are mainly characterised by gravel particles (>2000 microm). Wet and dry sieving procedures gave different particle size distributions, which can be interpreted by laser diffraction analysis and represented by Rosin-Rammler model. Concentrations of Zn, Cu and Cd were higher in the stream sediments than the tailing and background soil, while Mn, As, Sb and Hg are mainly concentrated in the tailing sample. Metal concentrations in the three stream sediment samples are correlated with both particle size dimensions (D(63.2)) and concentration of geochemical normalizers (iron and aluminium). These correlations are observed also for the pollutants that are mainly concentrated in tailing sample (Mn and As), denoting the importance of surface interactions also for the binding of these elements onto stream sediments. PMID:17400373

Giuliano, V; Pagnanelli, F; Bornoroni, L; Toro, L; Abbruzzese, C

2007-03-03

303

Microstructure and mechanical properties of high boron white cast iron  

Microsoft Academic Search

In this paper, high boron white cast iron, a new kind of wear-resistant white cast iron was developed, and its microstructure and mechanical properties were studied. The results indicate that the high boron white cast iron comprises a dendritic matrix and an interdendritic eutectic boride in as-cast condition. The distribution of eutectic boride with a chemical formula of M2B (M

Zhongli Liu; Yanxiang Li; Xiang Chen; Kaihua Hu

2008-01-01

304

DIETARY BORON: EVIDENCE FOR ESSENTIALITY AND HOMEOSTATIC CONTROL IN HUMANS AND ANIMALS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Boron is a bioactive element and a number of advances have been made in satisfying the five criteria for essentiality in humans and higher animals. 1) The element is present in tissues of different animals at comparable concentrations. Plasma concentrations (ug/mL) of boron are comparable in humans ...

305

A mathematical relationship for the explanation of ion exchange for boron adsorption  

Microsoft Academic Search

The present study was undertaken to investigate a method for boron removal from wastewaters from boric acid and borax plants. The ion-exchange method is effective for the removal of boron from solution. The experimental results under different initial concentrations are first converted into dimensionless variables by taking ratios of volumes and concentrations and subsequently plotted on double logarithmic graph papers.

Sami ?ahin

2002-01-01

306

Method for separating boron isotopes  

DOEpatents

A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

Rockwood, Stephen D. (Los Alamos, NM)

1978-01-01

307

Boron Hydride Polymer Coated Substrates.  

National Technical Information Service (NTIS)

A method is disclosed for coating a substrate with a uniformly smooth layer of a boron hydride polymer. The method comprises providing a reaction chamber which contains the substrate and the boron hydride plasma. A boron hydride feed stock is introduced i...

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

1986-01-01

308

Boron isotope fractionation during brucite deposition from artificial seawater  

NASA Astrophysics Data System (ADS)

Experiments involving boron incorporation into brucite (Mg(OH)2) from magnesium-free artificial seawater with pH values ranging from 9.5 to 13.0 were carried out to better understand the incorporation behavior of boron into brucite and the influence of it on Mg/Ca-SST proxy and ?11B-pH proxy. The results show that both the concentration of boron in deposited brucite ([B]d) and its boron partition coefficient (Kd) between deposited brucite and final seawater are controlled by the pH of the solution. The incorporation capacity of boron into brucite is almost the same as that into corals, but much stronger than that into oxides and clay minerals. The isotopic compositions of boron in deposited brucite (?11Bd) are higher than those in the associated artificial seawater (?11Bisw) with fractionation factors ranging between 1.0177 and 1.0569, resulting from the preferential incorporation of B(OH)3 into brucite. Both boron adsorptions onto brucite and the precipitation reaction of H3BO3 with brucite exist during deposition of brucite from artificial seawater. The simultaneous occurrence of both processes determines the boron concentration and isotopic fractionation of brucite. The isotopic fractionation behaviors and mechanisms of boron incorporated into brucite are different from those into corals. The existence of brucite in corals can affect the ?11B and Mg/Ca in corals and influences the Mg/Ca-SST proxy and ?11B-pH proxy negatively. The relationship between ?11B and Mg/Ca in corals can be used to judge the existence of brucite in corals, which should provide a reliable method for better use of ?11B and Mg/Ca in corals to reconstruct paleo-marine environment.

Xiao, J.; Xiao, Y. K.; Liu, C. Q.; Jin, Z. D.

2011-07-01

309

Naturalized salmonid populations occur in the presence of elevated trace element concentrations and temperatures in the firehole river, yellowstone National Park, Wyoming, USA  

USGS Publications Warehouse

We investigated the effects of geothermally influenced waters on the distribution of rainbow trout, Oncorhynchus mykiss, and brown trout, Salmo trutta, in the Firehole River and its tributaries in Yellowstone National Park (WY, USA) from June 1997 to June 1998. Geothermal features in the Firehole River basin elevate mineral content and temperature in portions of the river and its tributaries. We found concentrations of boron and arsenic to be elevated in geothermally influenced areas compared with upstream sites. Boron concentrations occasionally exceeded 1,000 ??g/L, a proposed limit for the protection of aquatic organisms. Arsenic concentrations occasionally exceeded 190 ??g/L, the chronic ambient water quality criterion. Temperatures in geothermally influenced sites ranged up to 30??C and were consistently 5 to 10??C higher than upstream sites unaffected by geothermal inputs. Rainbow trout occurred at sites with elevated concentrations of boron, arsenic, and other trace elements and elevated water temperatures. Rainbow trout inhabited and spawned at sites with the most elevated trace element concentrations and temperatures; however, brown trout were absent from these sites. Water temperature may be the major factor determining brown trout distributions, but we cannot exclude the possibility that brown trout are more sensitive than rainbow trout to boron, arsenic, or other trace elements. Further investigations are needed to determine species-specific tolerances of boron, arsenic, and other trace elements among salmonids.

Goldstein, J. N.; Hubert, W. A.; Woodward, D. F.; Farag, A. M.; Meyer, J. S.

2001-01-01

310

PIUS boron transport phenomena - A comparison of experiments with simulations  

SciTech Connect

In the process inherent ultimate safety (PIUS) reactor, the primary system is via thermal barriers in direct contact with a large pool of cold, highly borated water. In severe transients that would normally entail a risk of core damage, this borated water enters the primary system and shuts down the reactor, or reduces its power to a safe level and ensures cooling. The distribution of this inflowing borated water in the primary system is important for the transient behavior of the reactor. An example of such a transport phenomenon encountered in a PIUS reactor is an uncollected boron dilution transient, corresponding to inadvertent control rod withdrawal in a present-day pressurized water reactor. In this transient, a non-uniform boron distribution occurs in the primary system, and it is important to predict the boron distribution correctly in the primary system during the entire transient. A test loop of PIUS at ABB Atom's engineering laboratories was used to investigate large-scale boron transport phenomena. The test loop was used for comparing the standard solution methods in the RIGEL code with the improved model for tracking boron and entalphy front propagation. The test cases have demonstrated and verified the ability of the RIGEL code to predict boron transport phenomena with sufficient accuracy, using the improved transport delay model.

Bredolt, U.

1990-01-01

311

Boron recovery from clay waste using Diaion CRB-02 resin.  

PubMed

A two-step process for boron recovery from clay waste is proposed in the present work. The leachate obtained after the clay waste was leached with sulphuric acid solution was treated with Diaion CRB-02 - a boron-specific resin for the separation of boron from the alkaline species in the leachate. The batch studies showed that a maximum boron recovery of about 95% was obtained at a pH value of 8.0, an initial boron concentration of 50 mg L(-1), a contact time of 24 h and a temperature of 25 degrees C. Equilibrium sorption data fitted the Langmuir isotherm. Column studies were carried out using different inlet boron concentrations and flow rates at a pH value of 8.0 and a temperature of 25 degrees C. The Yoon-Nelson and Thomas models were used to describe the dynamic behaviour of the column and to determine the column kinetic parameters. By these models and graphical integration, the column capacity values were found to be 7.3-8.5 mg g(-1) and 7.1-8.5 mg g(-1), respectively, and the 50% breakthrough time values were found to be 21-155 min and 19-149 min, respectively, depending on the inlet concentration and flow rate. It was observed that about 76% of the boron in the leachate solution could be recovered at an inlet boron concentration of 250 mg L(-1), a flow rate of 2.5 mL min(-1), a pH value of 8.0 and a temperature of 25 degrees C. PMID:20426274

Kipçak, I; Ozdemir, M

2010-03-01

312

INFLUENCE OF SOIL SOLUTION SALINITY ON BORON ADSORPTION BY SOILS  

Microsoft Academic Search

Boron (B) adsorption on two arid-zone soils from the San Joaquin Valley of California was investigated as a function of equilibrium solution B concentration (0-250 mg Lj1), solution pH (3-12), and electrical conductivity (EC, 0.3 or 7.8 dS mj1). Boron adsorption on both soils increased with increasing pH, reached a maximum near pH 9, and decreased with further increases in

Sabine Goldberg; Donald L. Suarez; Peter J. Shouse

2008-01-01

313

Cathodic-arc deposition with boron-alloyed titanium cathodes  

Microsoft Academic Search

Titanium cathodes containing low boron concentrations were recently found to be important for (1) the reduction of droplet emission and (2) the formation of a denser structure of reactively deposited Ti–B–N hard coatings. Based on these results, detailed studies on the cathode behaviour and the Ti–B–N coating properties were performed using titanium cathodes containing 0–7.5at% boron and cemented carbides and

Martin Balzer; Herbert Kappl; Hermann A Jehn; Volker Güther

1999-01-01

314

Use of boron waste as an additive in red bricks  

SciTech Connect

In boron mining and processing operations, large amounts of clay containing tailings have to be discarded. Being rich in boron, the tailings do not only cause economical loss but also pose serious environmental problems. Large areas have to be allocated for waste disposal. In order to alleviate this problem, the possibility of using clayey tailings from a borax concentrator in red brick manufacturing was investigated. Up to 30% by weight tailings addition was found to improve the brick quality.

Uslu, T.; Arol, A.I

2004-07-01

315

HEALTH EFFECTS OF CHRONIC EXPOSURE TO ARSENIC VIA DRINKING WATER IN INNER MONGOLIA: IV. DISTRIBUTION OF ARSENIC CONCENTRATIONS IN WELLS  

EPA Science Inventory

HEALTH EFFECTS OF CHRONIC EXPOSURE TO ARSENIC VIA DRINKING WATER IN INNER MONGOLIA: IV. DISTRIBUTION OF ARSENIC CONCENTRATIONS IN WELLS Zhixiong Ning, B.S., Zhiyi Liu,B.S., Shiying Zhang, B.S., Chenglong Ma, B.S., Inner Mongolia Ba Men Anti-epidemic Station, Michael Ri...

316

Concentration and distribution of butyltin compounds in a heavy tanker route in the strait of Malacca and in Tokyo Bay  

Microsoft Academic Search

The distribution of butyltins was investigated in seawater at 20 stations (n=69) along the tanker route in the Strait of Malacca and in Tokyo Bay, areas of potential release of toxic organotin compounds to the aquatic environment from large vessels coated with antifouling paints containing tributyltin (TBT) compounds. Relatively high concentrations of butyltins were observed along the Strait of Malacca

Shinya Hashimoto; Masami Watanabe; Yasushi Noda; Toshihumi Hayashi; Yoshinobu Kurita; Yasusuke Takasu; Akira Otsuki

1998-01-01

317

Effect of Surfactant Concentration and Operating Temperature on the Drop Size Distribution of Silicon Oil Water Dispersion  

Microsoft Academic Search

The effect of sodium lauryl sulphate (SLES) surfactant and the operating temperature on the drop size distribution of a 350 cSt Dow Corning 200 series oil water dispersion was successfully studied. The dispersion was prepared in a standard 6 litres mixing tank at different impeller speeds. A measurement of the SLES critical micelle concentration (CMC) at 25°C was carried out.

2007-01-01

318

Effect of Surfactant Concentration and Operating Temperature on the Drop Size Distribution of Silicon Oil Water Dispersion  

Microsoft Academic Search

The effect of sodium lauryl sulphate (SLES) surfactant and the operating temperature on the drop size distribution of a 350 cSt Dow Corning 200 series oil water dispersion was successfully studied. The dispersion was prepared in a standard 6 litres mixing tank at different impeller speeds. A measurement of the SLES critical micelle concentration (CMC) at 2588888C was carried out.

Amer El-Hamouz

2007-01-01

319

Distribution of charge-carrier concentration derived from the current of an electrochemical reaction in GaAs-based structures  

SciTech Connect

This paper describes a technique for measuring the distribution of carrier concentration in thin epitaxial GaAs structures from the current of the electrochemical reaction across the semiconductor-electrolyte interface at zero bending of energy bands, this is verified by measuring the current induced by strongly absorbed light. Structure layers are etched off either photoelectrochemically or chemically.

Kolbasov, G.Ya.; Vas`ko, A.T.; Taranets, T.A.; Kolmakova, T.P. [Sapphire Scientific Research Institute, Moscow (Russian Federation)

1995-08-01

320

Frequency distributions and spatially dependent variability of ammonium and nitrate concentrations in soil under grazed and ungrazed grassland  

Microsoft Academic Search

The frequency distributions of soil NO3- and NH4+ concentrations under grazed and ungrazed grassland were found to be lognormal, irrespective of time of year or soil depth. The variance and skewness of the sample values increased with stocking density and use of N fertilizer. An analysis of the spatial dependence of the variability using the semivariogram showed a high ‘nugget’

RE White; Rosalyn A Haigh; Jh Macduff

1987-01-01

321

Quantitative fluorescence microscopy yields distributions of concentration and photobleaching rate in 5ALA-induced protoporphyrin IX in cell population  

NASA Astrophysics Data System (ADS)

the variation in photodynamic dose achieved with protoporphyrin Ix (PPIX) and laser radiation was assessed in a cancer cell culture. the distributions of initial PPIX concentration, photobleaching light dose, and photodynamic dose were measured on 124 individual cells (rat mammary cancer cell line, MTF7) using video fluorescence microscopy.

Awazu, Kunio; Jacques, Steven L.

1995-05-01

322

Stress intensity factors for an internal or edge crack in a circular elastic disk subjected to concentrated or distributed loads  

Microsoft Academic Search

Stress intensity factors for an internal or edge crack in a circular elastic disk subjected to concentrated or distributed loads are obtained using the singular integral equation technique. First, a solution for the uncracked case is obtained using the complex variable method, and then employing the superposition technique the crack problem is reduced to a perturbation problem. By integrating the

Y. L. Xu; F. Delale

1992-01-01

323

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

DOEpatents

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

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

1986-01-01

324

Distribution of Exposure Concentrations and Doses for Constituents of Environmental Tobacco Smoke  

Microsoft Academic Search

The ultimate goal of the research reported in this series of three articles is to derive distributions of doses of selected environmental tobacco smoke (ETS)-related chemicals for nonsmoking workers. This analysis uses data from the 16-City Study collected with personal monitors over the course of one workday in workplaces where smoking occurred. In this article, we describe distributions of ETS

Judy S. LaKind; Michael E. Ginevan; Daniel Q. Naiman; Anthony C. James; Roger A. Jenkins; Michael L. Dourson; Susan P. Felter; Carol G. Graves; Robert G. Tardiff

1999-01-01

325

Distributive tendency of element concentrations in limestone soils in eastern China  

Microsoft Academic Search

Twenty-eight soil profiles studied were collected from the eastern China. They belong to brown soil, drab soil, yellow brown\\u000a soil, brown limestone soil and red limestone soil. The concentrations of Ca and Mg in soils decrease and the concentrations\\u000a of Fe,Al,Zn,Pb,Cd, and Hg increase from north to south. There is no significant correlation between the element concentrations\\u000a and soil organic

Yanmao Wen; Shuiquan Zeng; Shurong Pan; Yuzhen Luo

1995-01-01

326

The Spatial Distribution of Tropospheric Ozone Concentration Associated to Land Use in the Sao Paulo Metropolitan Area, Brazil  

NASA Astrophysics Data System (ADS)

Atmospheric Pollution presents a great challenge in the environmental and health management of the great urban centres, affecting all who reside in these locations. Presently, one of the most hazardous pollutants in the São Paulo Metropolitan Area (SPMA) is tropospheric ozone (O3). Its formation and control are influenced by a number of different factors, which involve precursor emission, atmospheric and environmental variables such as incoming shortwave solar radiation, and land use in the surroundings of the monitoring site (which alter atmospheric chemistry locally), creating a complex picture of temporal and spatial distribution of this pollutant in the study area. In addition to its complexity, O3 does not present a decreasing tendency through the years in the study area and its highest concentrations are measured in places often visited by the population, such as urban parks and squares, yet typical of having lower concentrations of vehicular pollution. In order to properly assess these issues, a better understanding of the processes related to the control of tropospheric ozone is required. Using data from the State Environmental Agency (CETESB), we intend to study the spatial distribution of tropospheric ozone in the SPMA. Previous works on the subject have shown that land use is an important factor in the control of O3 concentrations. From this understanding, we intend to look for associations between ozone concentrations and land use throughout the city, and also in specific locations, such as parks and squares, known for high ozone concentrations in the city. In order to assess the impact of land use change in the pollutant's concentration, the atmospheric model WRF/Chem will be used. This will be done by replacing, in the model, a typically urbanized area in the city by that of a park, and checking the impacts on ozone concentrations afterwards. Through sensitivity tests in the model, we also intend to work with other parametrizations that define the impact of urbanization in the concentration and spatial distribution of tropospheric ozone.

Chiquetto, Julio; Siqueira Silva, Maria Elisa

2013-04-01

327

In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy  

SciTech Connect

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

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

1999-06-06

328

Thickness-dependent bending modulus of hexagonal boron nitride nanosheets.  

PubMed

Bending modulus of exfoliation-made single-crystalline hexagonal boron nitride nanosheets (BNNSs) with thicknesses of 25-300 nm and sizes of 1.2-3.0 microm were measured using three-point bending tests in an atomic force microscope. BNNSs suspended on an SiO(2) trench were clamped by a metal film via microfabrication based on electron beam lithography. Calculated by the plate theory of a doubly clamped plate under a concentrated load, the bending modulus of BNNSs was found to increase with the decrease of sheet thickness and approach the theoretical C(33) value of a hexagonal BN single crystal in thinner sheets (thickness<50 nm). The thickness-dependent bending modulus was suggested to be due to the layer distribution of stacking faults which were also thought to be responsible for the layer-by-layer BNNS exfoliation. PMID:19713592

Li, Chun; Bando, Yoshio; Zhi, Chunyi; Huang, Yang; Golberg, Dmitri

2009-08-28

329

Biaxial compressive strain engineering in graphene/boron nitride heterostructures.  

PubMed

Strain engineered graphene has been predicted to show many interesting physics and device applications. Here we study biaxial compressive strain in graphene/hexagonal boron nitride heterostructures after thermal cycling to high temperatures likely due to their thermal expansion coefficient mismatch. The appearance of sub-micron self-supporting bubbles indicates that the strain is spatially inhomogeneous. Finite element modeling suggests that the strain is concentrated on the edges with regular nano-scale wrinkles, which could be a playground for strain engineering in graphene. Raman spectroscopy and mapping is employed to quantitatively probe the magnitude and distribution of strain. From the temperature-dependent shifts of Raman G and 2D peaks, we estimate the TEC of graphene from room temperature to above 1000K for the first time. PMID:23189242

Pan, Wei; Xiao, Jianliang; Zhu, Junwei; Yu, Chenxi; Zhang, Gang; Ni, Zhenhua; Watanabe, K; Taniguchi, T; Shi, Yi; Wang, Xinran

2012-11-27

330

Boron isotopic fractionation related to boron sorption on humic acid and the structure of surface complexes formed  

Microsoft Academic Search

Boron isotopic fractionation during adsorption onto Ca-flocculated Aldrich humic acid (HA) has been investigated experimentally as a function of solution pH at 25°C and I = 0.15 M. Boron aqueous concentration and isotopic composition were determined by Cs2BO2+ Positive Thermal Ionization Mass Spectrometry analysis, while the structure of B surface complexes on HA was characterized using 11B Magic Angle Spinning

Emmanuel Lemarchand; Jacques Schott; Jérôme Gaillardet

2005-01-01

331

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

332

Boron Requirement in Cyanobacteria 1  

PubMed Central

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

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

1990-01-01

333

Boron hydride polymer coated substrates  

DOEpatents

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

Pearson, Richard K. (Pleasanton, CA); Bystroff, Roman I. (Livermore, CA); Miller, Dale E. (Livermore, CA)

1987-01-01

334

Boron hydride polymer coated substrates  

DOEpatents

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

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

1986-08-27

335

Tissue disposition of boron in male Fischer rats.  

PubMed

Boric acid (H3BO3), an inorganic acid with widespread commercial use and consumer exposure, impairs fertility in male rodents at dose levels lower than those required to cause other adverse effects. Previous studies found a testicular lesion in adult Fischer rats fed 9000 ppm boric acid (1575 ppm boron) and slightly reduced basal serum testosterone levels. A CNS-mediated hormonal component to this lesion was suggested. Detailed data on the tissue disposition of boron in the rat, including accessory sex organs and the brain, are lacking. This study examined the tissue disposition of boron in reproductive, accessory sex organs, and other selected tissues in adult male Fischer rats fed 9000 ppm boric acid to determine if selective accumulation of boron in reproductive tissues, accessory sex organs, and/or the brain might correlate with and explain the apparent selective testicular toxicity. Adult male Fischer rats were fed 9000 ppm boric acid for up to 7 days. Animals were killed at 1, 2, 3, 4, and 7 days after the start of exposure. Plasma and excised tissues were heat-digested in acid and analyzed for boron by inductively coupled argon plasma emission spectrometry (ICAP). With the exception of adrenal glands, control boron levels in all tissues examined were below 4 micrograms/g. There was a rapid increase in plasma and tissue boron 1 day after the start of exposure (range 2- to 20-fold), with the exception of adipose tissue. With the exception of bone and adipose tissue, all soft tissues examined, including the testis, epididymis, accessory sex organs, hypothalamus, and rest of brain, appeared to reach steady-state boron levels (range 12-30 micrograms/g) by 3-4 days. Bone boron levels continued to increase up to the termination at 7 days (40-50 micrograms/g by Day 7). Bone attained the greatest concentration of boron (2- to 3-fold over plasma levels) while levels in adipose tissue were 20% of plasma levels during the 7-day exposure period. All other tissues appeared to show no appreciable accumulation of boron over plasma levels. The data suggest that neither the apparent selective testicular toxicity nor the slight CNS hormonal effect associated with boric acid exposure can be explained on the basis of selective accumulation of boron in the testis or brain/hypothalamus, respectively. Thus, the testicular toxicity is likely the result of certain biological processes that are unique to the testis and which are targets of boron exposure. PMID:1949031

Ku, W W; Chapin, R E; Moseman, R F; Brink, R E; Pierce, K D; Adams, K Y

1991-10-01

336

Effects of Gender, Ethnicity, Body Composition, and Fat Distribution on Serum Leptin Concentrations in Children  

Microsoft Academic Search

The Ob protein leptin has been shown to be closely correlated with measures of body fat in humans and animals. Studies have suggested that there are both gender and ethnic differences in serum leptin concentrations, even after controlling for total and relative body fat and body mass index. We hypothesized that gender and ethnic dif- ferences in serum leptin concentrations

TIM R. NAGY; BARBARA A. GOWER; CHRISTINA A. TROWBRIDGE; CARL DEZENBERG; RICHARD M. SHEWCHUK; MICHAEL I. GORAN

337

On-Road measurement of particulate matter emissions from vehicles: particle concentration, size distribution and morphology  

Microsoft Academic Search

During summer 2010, we conducted a field experiment in Southern Michigan to measure on-road vehicle emissions. During the campaign, particulate matter (PM) concentrations were monitored with a Light Detection and Ranging (Lidar) and transmissometer system. The Lidar and transmissometer system measures PM mass concentration of vehicle exhaust using backscatter and extinction of an ultraviolet laser beam directed across the road.

N. Salvadori; S. China; J. Cook; H. D. Kuhns; H. Moosmuller; C. Mazzoleni

2010-01-01

338

Fabrication of boron sputter targets  

DOEpatents

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

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

1995-01-01

339

Determination of boron isotope ratios by Zeeman effect background correction-graphite furnace atomic absorption spectrometry  

Microsoft Academic Search

A new method for the determination of isotopic ratio of boron using Zeeman effect background correction-graphite furnace atomic absorption spectrometry with conventional atomizer and natural-boron hollow cathode source is described. The isotope-shift Zeeman effect at 208.9 nm is utilized for isotopic ratio determination. At a given concentration of total boron, the net absorbance decreases linearly with increasing 10B\\/11B ratio. The absorbances

S. Thangavel; S. V. Rao; K. Dash; J. Arunachalam

2006-01-01

340

Boron behavior during desalination of sea and underground water by electrodialysis  

Microsoft Academic Search

The degree of boron removal and its residual content in desalinated water vs. the feed boron concentration and the total salt content of a solution by means of electrodialysis have been studied. A comparative analysis of treatment of waters containing boron by the electrodialysis using the heterogeneous [MK-40 and MA-40 (Russia)], homogeneous [MK-100 and MA-100 (Ukraine)], and IONICS [CR67-HMR and

Ludmila Melnik; Olga Vysotskaja; Boris Kornilovich

1999-01-01

341

Coordination of boron in nominally boron-free rock forming silicates: Evidence for incorporation of BO 3 groups in clinopyroxene  

NASA Astrophysics Data System (ADS)

To explore mechanisms of B-incorporation in common chain silicates we have investigated synthetic diopside samples produced under boron-saturated conditions by 11B and 29Si magic-angle spinning (MAS) NMR and single-crystal NRA, FTIR, EMP and XRD/SREF techniques. Our samples contain 0.14-0.65 wt.% B 2O 3. NMR reveals that B is predominantly present in trigonal coordination in the clinopyroxene structure. This observation is supported by vibrational bands characteristic for B-O stretching in BO 3 groups in the range 1250-1400 cm -1 in polarised single crystal FTIR-spectra. Single crystal structure refinements suggest that boron replaces Si at the T site. Combined, these results suggest that boron replacement for Si at the T-site leads to disruption of one of the T-O bonds of the nominal clinopyroxene structure resulting in replacement of SiO 4 tetrahedra by BO 3 groups. Our results show that high concentrations of boron can be incorporated in the nominally boron-free diopside. Elevated B-concentrations in the present calcic clinopyroxenes are accompanied by modifications of the diopside crystal structure involving the breaking of one T-O bond and simultaneous formation of vacancies at the octahedral M2 site. These structural modifications destabilize the structure and constitute thereby limiting factors for incorporating higher boron concentrations in diopside.

Hålenius, Ulf; Skogby, Henrik; Edén, Mattias; Nazzareni, Sabrina; Kristiansson, Per; Resmark, Jeppa

2010-10-01

342

Investigation of Plutonium Concentration and Distribution in Burrowing Crayfish from the White Oak Creek Floodplain.  

National Technical Information Service (NTIS)

The White Oak floodplain was contaminated with several radionuclides, including exp 239 Pu, during the Manhattan Project in 1944. Plutonium distribution in the soil is nonhomogeneous. An investigation was conducted to deterine Pu accumulation in a residen...

M. S. Delaney R. C. Dahlman R. B. Craig

1979-01-01

343

Concentration Regimes of Biopolymers Xanthan, Tara, and Clairana, Comparing Dynamic Light Scattering and Distribution of Relaxation Time  

PubMed Central

The aim of this work was to evaluate the utilization of analysis of the distribution of relaxation time (DRT) using a dynamic light back-scattering technique as alternative method for the determination of the concentration regimes in aqueous solutions of biopolymers (xanthan, clairana and tara gums) by an analysis of the overlap (c*) and aggregation (c**) concentrations. The diffusion coefficients were obtained over a range of concentrations for each biopolymer using two methods. The first method analysed the behaviour of the diffusion coefficient as a function of the concentration of the gum solution. This method is based on the analysis of the diffusion coefficient versus the concentration curve. Using the slope of the curves, it was possible to determine the c* and c** for xanthan and tara gum. However, it was not possible to determine the concentration regimes for clairana using this method. The second method was based on an analysis of the DRTs, which showed different numbers of relaxation modes. It was observed that the concentrations at which the number of modes changed corresponded to the c* and c**. Thus, the DRT technique provided an alternative method for the determination of the critical concentrations of biopolymers.

Oliveira, Patricia D.; Michel, Ricardo C.; McBride, Alan J. A.; Moreira, Angelita S.; Lomba, Rosana F. T.; Vendruscolo, Claire T.

2013-01-01

344

Precise gamma ray measurement of the radial distribution of a cracking catalyst at diluted concentrations in a glass riser  

NASA Astrophysics Data System (ADS)

The radial concentration distribution of a cracking catalyst circulating in a glass riser of a cold model was precisely measured in diluted flow regime. Catalyst and compressed air were the components of the fluidized bed system. The gamma transmission measurements were carried out with a 241Am radioactive source and a scintillation NaI(Tl) detector. The gamma ray transmission profile of riser was evaluated and the main effects were identified. The standard uncertainty in the concentration values was evaluated as a function of the photopeak counts. A model was proposed to describe the profile curve of the empty riser as a function of the chordal length that fits experimental data adequately. A calibration of catalyst density carried out in static experiments and an integral evaluation of the radial scan were compared with punctual density. Under flow conditions the radial concentration distribution was measured at (2 16) kg/m3 and at (10 60) kg/m3 intervals. At two different airflow rates, concentration distribution tendency to move from the annular to the core region in the higher airflow, was observed.

Dantas, C. C.; Dos Santos, V. A.; Melo, A. C. B. A.; van Grieken, R.

2006-09-01

345

A MD study of low energy boron bombardment on silicon  

NASA Astrophysics Data System (ADS)

Low energy boron bombardment of silicon has been simulated at room temperature by means of molecular dynamics (MD). Tersoff potential T3 was used in the simulation smoothly linked to the universal potential. The boron-silicon interaction was simulated following the ideas of Tersoff for the SiC potential but modified to take into account, in the B-Si interaction, whether or not the neighbours of either of both are entirely or partially boron or silicon atoms. (001) Si-C with (/2×1) reconstruction surface was bombarded with boron at energies of 200 and 500 eV, which were initially chosen as good representative values of the low energy range of interest. Reliable results require a reasonable good statistic so that 100 impact points were chosen which were uniformly distributed over a representative area of a (/2×1) surface. Special care was taken to determine the kind of damage produced in a Si crystal by the slowing down of boron. It is described in detail the way to determine vacancies and interstitials. The damage produced can be classified in regions were the accumulation of damage does not allow to identify properly the type of defects produced and regions in which defects are isolated and can be beautifully identified in terms of the potential energy variation and the displacements of their neighbours. Clusters of vacancies and interstitials are determined. Mean number of interstitials, vacancies, adatoms, sputtering, etc. are summarised in a table. Range distributions of boron are also determined.

Pérez-Martín, A. M. C.; Domínguez-Vázquez, J.; Jiménez-Rodríguez, J. J.

2000-04-01

346

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

347

Control of glycolytic enzyme binding: effect of changing enzyme substrate concentrations on in vivo enzyme distributions  

Microsoft Academic Search

The effect of changing concentrations of glycolytic intermediates on the binding of phosphofructokinase, aldolase and pyruvate kinase to cellular particulate matter was investigated. Concentrations of glycolytic intermediates were altered by adding 2mM iodoacetic acid (IAA) to an incubation medium containing tissues isolated from the channelled whelkBusycon canaliculatum. Iodoacetic acid inhibited glyceraldehyde 3-phosphate dehydrogenase activity causing a 100–400 fold increase in

Stephen P. J. Brooks; Kenneth B. Storey

1993-01-01

348

Flux density distribution in the focal region of a solar concentrator system  

Microsoft Academic Search

In high temperature solar energy applications highly concentration optical systems, such as, e.g., parabolic dishes, achieve typical tradition flux densities <2 MW\\/M². In order to investigate thermo and photochemical reactions at temperatures <1500 K and radiation flux densities <2 MW\\/m² a solar furnace was built at Paul Scherrer Institute (PSI). This furnace is a two-stage concentrator. The first stage is

M. Schubnell; J. Keller; A. Imhof

1991-01-01

349

Distribution of indoor radon concentrations and uranium-bearing rocks in Texas  

Microsoft Academic Search

The purpose of this study was to compare regional patterns of indoor radon concentration with uranium-bearing rock zones\\u000a and county populations in Texas. Zones yielding radon concentrations that are relatively high for Texas include shale and\\u000a sandstone in northwest Texas; red beds in north-central Texas; felsic volcanic rocks in west Texas; and sandstone, limestone,\\u000a and igneous rocks in central Texas.

P. F. Hudak

1996-01-01

350

Two-dimensional tomography for gas concentration and temperature distributions based on tunable diode laser absorption spectroscopy  

NASA Astrophysics Data System (ADS)

A tomography system is presented that uses wavelength-scanned direct absorption of two transitions of a target species (NH3 in the demonstration experiment) to determine the distributions of gas concentration and temperature. The absorption measurements are performed simultaneously from four platforms that each rotate a beam from a single laser through an 11° arc, acquiring a data set from all four laser platforms in 100 ms to enable observation of dynamic flow events. The laser is wavelength scanned through two absorption transitions with different internal energy producing two sets of equations with species mole fraction and temperature as independent variables. The mole fraction and temperature distributions are reconstructed using the algebraic reconstruction technique (ART) for this set of incomplete projections. A numerical simulation is used to evaluate the measurement accuracy for measurements of an NH3 mixture escaping from an open pipe. This phantom distribution is then realized in the laboratory and the measurement strategy is demonstrated using a tunable diode laser absorption spectroscopy (TDLAS) measurement using a single laser near 1.5 µm to scan adjacent transitions in NH3. The reconstruction of NH3 concentration and gas temperature is compared with independently determined values to illustrate the fidelity of the tomographically reconstructed distributions for the NH3 mole fraction assuming a fixed temperature and for unknown mole fraction and temperature. Potential extensions of this research in the future include evaluation of other reconstruction algorithms and investigation of the dynamic distribution of various gases for combustion diagnostics.

Wang, F.; Cen, K. F.; Li, N.; Jeffries, Jay B.; Huang, Q. X.; Yan, J. H.; Chi, Y.

2010-04-01

351

Vertical and horizontal concentration distributions of ultrafine particles near a highway  

NASA Astrophysics Data System (ADS)

Assessment of human health effects associated with particles requires knowledge of their emission factors and dispersion characteristics. A field experiment was recently conducted to determine the vertical and horizontal dispersion of particles emitted from highway vehicles. The measurements were conducted near the highway I-90 in Liverpool (NY) over a flat terrain, where the predominant dispersion mechanisms were atmospheric turbulence and traffic-produced turbulence (TPT). Real-time vertical number concentration measurements were made using several identical water condensation particle counters (WCPCs) over nine heights up to 10 m. Three sites (at distances of 15, 50, and 100 m from the highway) were selected to study the concentration profiles. As previously observed at other sites, particle concentrations decay with increasing distance from highways. At the site closest to the highway, the highest concentration was observed under a downwind condition with the average wind speed ˜1 ms -1. Under conditions of low wind speed, particles from the highway are observed even at locations upwind of the highway. The vertical profiles of particle concentrations at different measurement locations varied with wind speed, wind direction and distance to the highway. The correlation coefficients of particle concentrations at different elevations reveal the characteristics of the plume dispersion and its development in the horizontal and vertical directions. The experimental results suggest the need for three-dimensional modeling of particle plumes from highways and the importance of considering TPT for accurate prediction of particle dispersion near roadways.

He, Meilu; Dhaniyala, Suresh

2012-01-01

352

Aircraft measurements of vertical and spatial distribution of aerosol concentration and size over different environments in India  

NASA Astrophysics Data System (ADS)

It is well known that atmospheric aerosols play a major role in climate change by directly scattering and absorbing the incoming and outgoing radiation as well as through modifying cloud properties, such as droplet size distribution and cloud lifetime. However, aerosol measurements, particularly their vertical distribution, are less and unevenly distributed around the globe. Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX) is an Indian National program conducted by the Indian Institute of Tropical Meteorology (IITM), Pune, India, during summer monsoon season May-September 2009. Under CAIPEEX program, an instrumented aircraft has been used to study background aerosol along with cloud microphysical properties and their interactions over different parts of India. This experiment has been carried out for the first time in India. During CAIPEEX, PCASP (Passive Cavity aerosol Spectro Photometer) which measures aerosol concentrations in the size range 0.1 to 3 microns is operated in the aircraft over different parts of India viz., Pathankot (May), Hyderabad (June), Bengaluru (June-July), Bareilly (July-August), Guwahati (August- September) and Pune (September). The preliminary results suggest that aerosol vertical distribution is observed up to a maximum of 7.0 - 7.5 km, with high surface concentrations and enhanced layers at higher altitudes. During monsoon period also high concentrations are observed. The spatial distribution of aerosols along the flight track shows aerosol gradient from one place to another place. Also thick haze is observed near Himalayas during the month of May. The results at all the locations showed high aerosol concentrations in the size range of 0.1 to 0.3 microns, steep decreasing trend from 0.3 - 0.6 microns and less concentration from 0.6 to 3 microns. In the size range of 0.1 to 0.3 microns the concentrations varied from 100-10000 particles/cc. In-depth analysis of CAIPEEX data gives a clear picture of aerosol distribution over different parts of India during monsoon season, which further helps to understand the cloud micro physics. This paper presents a glimpse of the CAIPEEX mission and the preliminary results of aerosol measurements over different environments in India.

Kumari B., Padma; S, Mahesh Kumar R.; R, Kulkarni J.; N, Goswami B.

2010-05-01

353

Daily Boron Intake from the American Diet  

Microsoft Academic Search

Interest in boron as a naturally occurring trace element nutrient from the food supply is increasing. Mounting evidence suggests that boron is essential to human beings. This study explores the major food and beverage contributors of boron and estimates of daily boron intake from the American diet. Previous estimates in the literature of dietary boron consumption are based on limited

CHARLENE J RAINEY; LESLIE A NYQUIST; ROBERT E CHRISTENSEN; PHILIP L STRONG; B DWIGHT CULVER; JAMES R COUGHLIN

1999-01-01

354

Minerals Yearbook, 1992: Boron.  

National Technical Information Service (NTIS)

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 be sales to textile-grade glass fibers, and soaps and detergents. California was the only d...

P. A. Lyday

1993-01-01

355

Minerals Yearbook, 1991: Boron.  

National Technical Information Service (NTIS)

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 textile-grade glass fibers, sales to distributors, and borosilicate glasses. Ca...

P. A. Lyday

1992-01-01

356

Wettability of Boron Carbide.  

National Technical Information Service (NTIS)

The work was presented at the conference, Advanced Joining Technologies from New Materials II, which was held in Cocoa Beach, USA, 2-4th of March. The conference proceedings will be published in 1994. The wettability of boron carbide has been examined by ...

T. Torvund O. M. Akselsen O. Grong J. H. Ulvensoen

1994-01-01

357

Sublimation of Boron.  

National Technical Information Service (NTIS)

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

R. W. Mar R. G. Bedford

1976-01-01

358

Statistical distribution of series of 12 monthly concentration samples for environmental classification of rivers  

NASA Astrophysics Data System (ADS)

Environmental monitoring and classification of rivers in the northern hemisphere is frequently hampered by lack of infrastructure in the scarcely populated areas of the north. Carefully designed economical methods are important. Analysis of 15 constituents in 14 rivers in Iceland show that monthly samples for a period of 1 year are sufficient for classification provided that the correct statistical distribution is known. Normalizing and plotting all the constituents in each river by rank shows systematic deviations from both the normal and lognormal distributions. When the constituents are pooled by river the result is one distribution for each river, all very similar. A new cumulative distribution function (DoC) is formed as the average of these. It has a long tail similar to that of the lognormal distribution but below the 60% quantile, the DoC differs a lot from the lognormal so if it is to be used, an unbiased estimate of the scale and location parameters will in most cases be difficult to obtain if more than 30-40% of the highest points is used. The influence of the DoC on the classification result is very strong when the 90% quantile is used for classification, but fades out at the 60% quantile. It is shown that the storage effect in rivers with a lake that holds some weeks flow in storage, can have a great influence on the classification result.

Eliasson, J.; Thordarson, T.

2007-08-01

359

Distribution of melanin-concentrating hormone neurons projecting to the medial mammillary nucleus.  

PubMed

The melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine are expressed in neurons located mainly in the hypothalamus that project widely throughout the CNS. One of the melanin-concentrating hormone main targets is the medial mammillary nucleus, but the exact origin of these fibers is unknown. We observed melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine immunoreactive fibers coursing throughout the mammillary complex, showing higher density in the pars lateralis of the medial mammillary nucleus, while the lateral mammillary nucleus showed sparse melanin-concentrating hormone innervation. The origins of these afferents were determined by using implant of the retrograde tracer True Blue in the medial mammillary nucleus. Double-labeled neurons were observed in the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus. A considerable population of retrogradely labeled melanin-concentrating hormone perikaryal profiles was also immunoreactive to neuropeptide glutamic acid-isoleucine (74+/-15% to 85+/-15%). The afferents from the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus to the medial mammillary nucleus were confirmed using implant of the anterograde tracer Phaseolus vulgaris leucoagglutinin. In addition, using double-labeled immunohistochemistry, we found no co-localization between neurons expressing melanin-concentrating hormone and adenosine deaminase (histaminergic marker) in the dorsal tuberomammillary nucleus. We hypothesize that these melanin-concentrating hormone projections participate in spatial memory process mediated by the medial mammillary nucleus. These pathways would enable the animal to look for food during the initial moments of appetite stimulation. PMID:12435428

Casatti, C A; Elias, C F; Sita, L V; Frigo, L; Furlani, V C G; Bauer, J A; Bittencourt, J C

2002-01-01

360

Temporal distribution of heavy metal concentrations in oysters Crassostrea rhizophorae from the central Venezuelan coast.  

PubMed

The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by local populations. No known values have been reported on trace metals in oysters from the central Venezuelan coast. We report the concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn in the soft parts of C. rhizophorae, which were collected bimonthly between March 2008 and March 2009, at two sampling areas from the Central Venezuelan Coast: Buche estuary and Mochima estuary. Our results show that for each metal there is a similar temporal variation pattern. The concentrations of the heavy metals reported in this work are useful as reliable baselines and can be used for comparison in future environment studies. Concentrations in C. rhizophorae from the Buche estuary can be interpreted to be high on a global scale for Cd, Cu, Ni and Mn, indicating atypically raised bioavailabilities. PMID:23746942

Alfonso, Juan A; Handt, Helga; Mora, Abrahan; Vásquez, Yaneth; Azocar, José; Marcano, Eunice

2013-06-05

361

Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils.  

PubMed

Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0-5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. PMID:23892068

Rhind, S M; Kyle, C E; Kerr, C; Osprey, M; Zhang, Z L; Duff, E I; Lilly, A; Nolan, A; Hudson, G; Towers, W; Bell, J; Coull, M; McKenzie, C

2013-07-25

362

Shear stress distribution measurement around adherent red cell in microchannel correlated with Poly-L-lysine concentration  

NASA Astrophysics Data System (ADS)

Measurement of shear stress distributions surrounding an adherent human red blood cell in microchannel flow was found using an experimental micron resolution particle image velocimetry technique. One micron accurate velocity field measurements can be analyzed using a post processing differencing algorithm to supply shear stress distribution measurements surrounding the cell. The cell to channel height aspect ratio was small enough to assume negelible pressure changes in the region of the red cell. This channel size enables accurate measurement of the Stokes flow while a poly-L-lysine coating is present in the channel to enable the red cell to adhere to the microchannel wall. A correlation between red cell lysis and poly-L-lysine concentration has also been found to conceptualize changes in membrane tension with varied concentration.

Pommer, Matthew S.; Meinhart, Carl D.

2004-11-01

363

CONCENTRATION AND DISTRIBUTION OF PAHS IN SOILS AFFECTED BY GRASSLAND FIRE  

Microsoft Academic Search

A study has been carried out to determine the affect of grassland fire on the distribution of polycyclic aromatic hydrocarbons (PAHs) in roadside soils of Marang district. 15 surfacial soil samples were collected from Kuala Tengah in Pulau Kerengga to Kg. Baharu in Merchang, a stretch of area bordering to the national trunk road, which frequently suffered from grassland fires.

Norhayati Mohd Tahir; Tan Hock Seng; Marinah Ariffin; Suhaimi Suratman; Lim Seang Hoe

2006-01-01

364

Vertical distribution and rotifer concentrations in the chemocline of meromictic lakes  

Microsoft Academic Search

The vertical distribution of planktonic rotifers has been analysed in relation to season in several meromictic lakes; a coastal lagoon with sea-water intrusion and three dissolution lakes from two karstic systems. Two species, Filinia hofmanni and a form of Anuraeopsis fissa have been found to be more or less restricted to the chemocline or adjacent strata any time they occurred.

María R. Miracle; Eduardo Vicente

1983-01-01

365

Sterol concentration and distribution in sunflower seeds ( Helianthus annuus L.) during seed development  

Microsoft Academic Search

Sunflower seeds are currently used for edible oil production. Among oil minor compounds, phytosterols are of special interest due to their cholesterol reducing properties. This paper reports studies on their accumulation and distribution in the embryo and hull, and the effects of temperature on phytosterol contents in sunflower seed produced under both conventional and organic field conditions. An optimised method

Jane Roche; Marion Alignan; Andrée Bouniols; Muriel Cerny; Zephirin Mouloungui; Othmane Merah

2010-01-01

366

Concentration distribution and viscosity of ice-slurry in heterogeneous flow  

Microsoft Academic Search

Mathematical modeling of two phase flows, especially liquid–solid flows is very complex. Especially when a distribution of the solid phase in a carrier liquid is not homogenous but heterogeneous or even when a moving or stationary bed occurs. In this case, the rheological characteristics of suspension are changing and affect transport characteristics. Therefore, the slurry flow may present a Newtonian

Andrej Kitanovski; Alojz Poredoš

2002-01-01

367

Geogenic distribution and baseline concentration of heavy metals in sediments of the Ganges River, India  

Microsoft Academic Search

The search for a better understanding of heavy metal distribution in large river sediments is a major concern in the exogenic cycling of elements through fluvial processes and in assessing the effects of anthropogenic influences. From the Asian continent, the Ganges River contributes a significant amount of sediments to the world's ocean. Freshly deposited sediments of the Ganges River were

Munendra Singh; German Müller; I. B Singh

2003-01-01

368

Size distribution of siderophile element concentrations in black magnetic spherules from deep-sea sediments  

SciTech Connect

A size spectrum of black magnetic spherules which were collected from deep-sea sediments was obtained. Siderophile element (Fe, Co, Ir, and Au) concentrations in 100 spherules, each of them larger than 100 mm, were determined with instrumental neutron activation analysis. About 20% of the spherules showed (Ir/Fe) and (Co/Fe) ratios which cannot be explained clearly by an iron meteorite parent for the spherules. Further, there was no strong correlation between the size and the chemical concentration rations (Ir/Fe), (Co/Fe), and (Au/Fe)) of the spherules.

Yamakoshi, K.; Nogami, K.; Shimamura, T.

1981-04-10

369

Formation of a solid lubricant in boron carbide by nitrogen ion implantation and laser annealing  

SciTech Connect

A boron nitride(lubricant)/boron carbide composite (approximately 70% boron nitride) has been formed in approximately the first 750 A of surface and near-surface regions of a polycrystalline boron carbide sample by implanting nitrogen (N) ions at 100 keV with a total dose of 4{times}10{sup 17} N ions/cm{sup 2} followed by xenon chloride laser annealing. The composition and the profile of the boron, carbon, and nitrogen in the sample at various stages were determined by Rutherford backscattering spectrometry. During laser annealing, the deeply implanted N atoms diffused back toward the heated surface with about 50% of them remaining in the near-surface region. Argon sputtering and x-ray photoelectron spectroscopy measurements confirmed the formation and distribution of boron nitride.

Reeber, R.R. (Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599-3255 (USA)); Kusy, R.P. (Biomedical Engineering and Dental Research Center, University of North Carolina, Chapel Hill, North Carolina 27599-7455 (USA)); Yu, N.; Chu, W. (Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5506 (USA))

1990-03-12

370

The influence of the concentration of surface boron atoms on the properties of column packings with bonded C 18 groups, prepared from controlled-porosity glasses II. Liquid chromatography  

Microsoft Academic Search

In the preparation of C18-bonded phases higher coverage densities were obtained using dimethylaminodimethyl-n-octadecylsilane than chlorodimethyl-n-octadecylsilane as the reagents. The HPLC results show the very high hydrophobicity of the materials obtained. The elution mechanism has been found to be independent of the coverage density on the boron-enriched glass surface in the range 2.3–4.0 ?mol\\/m2.

Z. Suprynowicz; J. Rayss; A. L. Dawidowicz; R. Lodkowski

1985-01-01

371

Development of Tunable Diode Laser Absorption Tomography for Determination of Spatially Resolved Distributions of Water Vapor Temperature and Concentration  

NASA Astrophysics Data System (ADS)

Optical diagnostic techniques used in high speed, high enthalpy flows, such as in a supersonic ramjet (scramjet) combustor, allow direct measurement of temperature and species concentration. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a common laser based measurement technique for measuring temperature and species concentration in harsh environments such as chemically reacting flows. TDLAS is a one-dimensional, path integrated measurement that provides average values of the measured quantities and can be affected by gradients in the measurement space. By combining TDLAS with tomographic image reconstruction a two-dimensional spatially resolved distribution can be obtained. This technique is called Tunable Diode Laser Absorption Tomography. TDLAT has been developed for the purpose of making temperature and species concentration measurements on the supersonic combustion facility at the Aerospace Research Laboratory. TDLAT has been developed for the purpose of making two-dimensional measurements of water vapor concentration, which when combined with Stereoscopic Particle Image Velocimetry can be used to calculate supersonic combustion efficiency of a scramjet combustor. This measurement system has been used in measurements of a flat flame burner from which two-dimensional distributions of temperature and water vapor concentration have been calculated. The calculated temperatures were then compared to measurements made on the same flat flame burner. Reconstructions of temperature and concentration show the structure of the flat flame burner, resolving regions of ambient room air, nitrogen co-flow, mixing layer and hot burner core. The TDLAT system was then installed on the supersonic combustion facility, where measurements were made for a known mole fraction of steam injected into the free stream. The TDLAT system was then used to measure water vapor concentration and temperature for clean-air combustion for an equivalence ratio of 0.17. The resulting values were then used to calculate supersonic combustion efficiency of the scramjet combustor.

Bryner, Elliott

372

Estimation of the temporal and spatial distribution of dust concentration over China by combining PM10 and conventional meteorological observations.  

PubMed

In this paper, we will present a simple algorithm to estimate the temporal and spatial distribution of dust mass concentration by combining PM10 and conventional meteorological observations. The efficiency of the algorithm has been demonstrated by applying it to analyze the dust source, transport, and dissipation of the dust storm which occurred in the west region of Pa-tan-chi-lin Desert at 0200 BST 27 March, 2004. PMID:19882221

Zhao, Fengsheng; Li, Xiaoqing; Gai, Changsong; Gao, Wenhua

2009-10-31

373

Mathematical modeling and finite element simulation of slow release of drugs using hydrogels as carriers with various drug concentration distributions.  

PubMed

In drug release systems using hydrogels as carriers, the presence of the polymer network will reduce the drug release rate, which can extend the release period. For a controlled-release process of drug, usually the ideal situation is to get a zero-order drug release rate. In this paper, the mathematical model of hydrogel swelling processes is constructed on the basis of a biphasic theory, and then an integrated equation that considers both water convection and drug diffusion phenomena is used to describe the drug release process. The effects of the initial drug concentration with nonuniform distributions along the radial direction of hydrogel carriers on the release of drugs are studied through simulating two-dimensional hydrogel swelling processes by means of the COMSOL Multiphysics software. The simulation results show that along with the hydrogel swelling, the drug release rate is changing, and the major influencing factors of the drug release rate are water convection and drug diffusion coefficient, which are affected by water volume fraction, drug concentration distribution in matrix, and carrier radius. The results also indicate that the initial drug concentration distribution following a sine curve can result in an ideal zero-order release process. PMID:23526640

Xu, Yihan; Jia, Yuxi; Wang, Zhao; Wang, Zhaojing

2013-03-21

374

The relationship of blood- and urine-boron to boron exposure in borax-workers and usefulness of urine-boron as an exposure marker.  

PubMed Central

Daily dietary-boron intake and on-the-job inspired boron were compared with blood- and urine-boron concentrations in workers engaged in packaging and shipping borax. Fourteen workers handling borax at jobs of low, medium, and high dust exposures were sampled throughout full shifts for 5 consecutive days each. Airborne borax concentrations ranged from means of 3.3 mg/m3 to 18 mg/m3, measured gravimetrically. End-of-shift mean blood-boron concentrations ranged from 0.11 to 0.26 microgram/g; end-of-shift mean urine concentrations ranged from 3.16 to 10.72 micrograms/mg creatinine. Creatinine measures were used to adjust for differences in urine-specific gravity such that 1 ml of urine contains approximately 1 mg creatinine. There was no progressive increase in end-of-shift blood- or urine-boron concentrations across the days of the week. Urine testing done at the end of the work shift gave a somewhat better estimate of borate exposure than did blood testing, was sampled more easily, and was analytically less difficult to perform. Personal air samplers of two types were used: one, the 37-mm closed-face, two-piece cassette to estimate total dust and the other, the Institute of Occupational Medicine (IOM) sampler to estimate inspirable particulate mass. Under the conditions of this study, the IOM air sampler more nearly estimated human exposure as measured by blood- and urine-boron levels than did the sampler that measured total dust.(ABSTRACT TRUNCATED AT 250 WORDS)

Culver, B D; Shen, P T; Taylor, T H; Lee-Feldstein, A; Anton-Culver, H; Strong, P L

1994-01-01

375

CONCENTRATIONS AND PHASE DISTRIBUTIONS OF NITRATED AND OXYGENATED POLYCYCLIC AROMATIC HYDROCARBONS IN AMBIENT AIR  

EPA Science Inventory

The concentrations of nitrated and oxygenated aromatic hydrocarbons (PAH) in ambient air, both in the vapor phase and adsorbed on airborne particles, were measured over a 12-month period in Houston, Texas. easonal variations in the levels of the target compounds were weakly relat...

376

Distribution of Genetic Marker Concentrations for Fecal Indicator Bacteria in Sewage and Animal Feces  

EPA Science Inventory

The application of quantitative real-time PCR (qPCR) methods for the identification of fecal microorganisms in surface waters has the potential to revolutionize water quality monitoring worldwide. Unlike traditional cultivation methods, qPCR estimates the concentration of gen...

377

Measurements of the Concentration and Size Distribution of Particles in the Arctic Air of Greenland  

Microsoft Academic Search

A series of aerosol measurements at a remote site on the Greenland ice cap (Fist Clench, 210 miles east of Thule Air Force Base, and Camp Century, 150 miles east of Thule) was conducted during August 1959 and March 1960 to determine the concentration and size distri- bution of the natural aerosol in air which is free of direct contamination

Robert W. Fenn

1960-01-01

378

THE SPATIAL DISTRIBUTION OF PHYTOPLANKTON CHLOROPHYLL CONCENTRATIONS IN NARRAGANSETT BAY USING AIRCRAFT REMOTE SENSING  

EPA Science Inventory

During the summer of 2002, phytoplankton chlorophyll concentrations were determined in Narragansett Bay, Rhode Island using a light aircraft equipped with the MicroSAS remote sensing system. From an altitude of 300 m, the three sensor system measured sea surface radiance (Lt), sk...

379

Comparison of Four Species Sensitivity Distribution Methods to Calculate Predicted No Effect Concentrations for Bisphenol A  

Microsoft Academic Search

Bisphenol A (BPA, CAS RN 80-05-7) is a high production volume chemical used as an intermediate in the production of polycarbonate plastic and epoxy resins. During its manufacture and use, some emissions to surface waters are anticipated. Chronic predicted no effect concentrations (PNECs) for aquatic systems are used to support the assessment of potential risks to aquatic organisms in receiving

C. A. Staples; K. B. Woodburn; G. M. Klecka; E. M. Mihaich; A. T. Hall; L. Ortego; N. Caspers; S. G. Hentges

2008-01-01

380

THE CONCENTRATION AND DISTRIBUTION OF RADIUM IN THE NORMAL HUMAN SKELETON  

Microsoft Academic Search

S>Maximum permissible levels of irradiation to the human body have been ; assigned from experience gained in the past with radium poisoning cases. ; Previous data on normal levels of radium concentration in the body are limited ; and show a wide variation. A comprehensive study of radium levels in the human ; skeleton has been made in this work

A. Walton; R. Kologrivov; J. L. Kulp

1959-01-01

381

Concentration and Spatial Distribution of Selected Constituents in Detroit River Bed Sediment Adjacent to Grassy Island, Michigan, August 2006  

USGS Publications Warehouse

In August 2006, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, collected sediment?core samples from the bed of the Detroit River adjacent to Grassy Island. The goal of the sampling was to assess the distribution and concentration of chemical constituents in sediment adjacent to Grassy Island, which was operated from 1960 to 1982 as a confined disposal facility to hold dredge spoils. On August 31, 2006, seven samples were collected at four locations in the Detroit River on the north, south, east, and west sides of the island. Metals concentrations in the riverbed sediment tended to be higher on the west side of the island, whereas organic?compound concentrations were generally higher on the east side. Comparison of results from this sampling to concentrations reported in previous studies indicates that the concentrations of inorganic constituents, mainly metals, in the riverbed sediment around Grassy Island fell within the range of concentrations found regionally throughout the Detroit River and in most cases have lower mean and median values than found elsewhere regionally in the Detroit River. Comparison of results from the August 31, 2006, sampling to U.S. Environmental Protection Agency risk?based sediment?quality guidelines indicates that 18 organic constituents for which an ecological screening level (ESL), and (or) a threshold effect concentration (TEC), and (or) a probable effect concentration (PEC) has been defined exceeded one or more of these guidelines at least once. Further work would be needed to determine whether constituent concentrations in the river sediment are related to constituent runoff from Grassy Island.

Hoard, C. J.

2008-01-01

382

Distribution of 210Pb and 210Po concentrations in wild berries and mushrooms in boreal forest ecosystems.  

PubMed

The activity concentrations and distribution of 210Pb and 210Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of 210Pb and 210Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems>leaves>berries (i.e. fruits). The activity ratios of 210Po/210Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of 210Pb and especially 210Po were higher than in fruits of the wild berries. The highest activity concentration of 210Pb was detected in Cortinarius armillatus L. (16.2 Bq kg(-1) d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg(-1) d.w.). The 210Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg(-1) d.w. (Russula paludosa L.) to 1174 Bq kg(-1) d.w. (L. vulpinum L.). In general, the highest activity concentrations of 210Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of 210Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of 210Po were higher than those of 210Pb. 210Po and 210Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by 137Cs from the Chernobyl fallout. PMID:19800659

Vaaramaa, Kaisa; Solatie, Dina; Aro, Lasse

2009-10-02

383

Fuel-Rich Solid Propellant Boron Combustion.  

National Technical Information Service (NTIS)

Single particle boron ignition and combustion models developed in earlier phases of this program have been utilized and extended to treatment of boron cloud ignition, oxidizer depletion effects on cloud combustion time, laminar flame speeds in boron dust ...

J. Komar M. K. King R. S. Fry

1984-01-01

384

Time evolution of a fractal distribution: Particle concentrations in free-surface turbulence  

NASA Astrophysics Data System (ADS)

Steady-state turbulence is generated in a tank of water and the trajectories of particles forming a compressible system on the surface are tracked in time. The initial uniformly distributed floating particles coagulate and form a fractal structure, a rare manifestation of a strange attractor observable in real space. The surface pattern reaches a steady state in approximately 1 s. Measurements are made of the fractal dimensions Dq(t) (q=1 to 6) of the floating particles starting with the uniform distribution Dq(0)=2 for Taylor Microscale Reynolds number Re??160. Focus is on the time evolution of the correlation dimension D2(t) as the steady state is approached. This steady state is reached in several large eddy turnover times and does so at an exponential rate.

Larkin, Jason; Goldburg, Walter; Bandi, M. M.

2010-07-01

385

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

SciTech Connect

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

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

2011-03-01

386

Boron neutron capture therapy (BNCT) for the treatment of liver metastases: biodistribution studies of boron compounds in an experimental model.  

PubMed

We previously demonstrated the therapeutic efficacy of different boron neutron capture therapy (BNCT) protocols in an experimental model of oral cancer. BNCT is based on the selective accumulation of (10)B carriers in a tumor followed by neutron irradiation. Within the context of exploring the potential therapeutic efficacy of BNCT for the treatment of liver metastases, the aim of the present study was to perform boron biodistribution studies in an experimental model of liver metastases in rats. Different boron compounds and administration conditions were assayed to determine which administration protocols would potentially be therapeutically useful in in vivo BNCT studies at the RA-3 nuclear reactor. A total of 70 BDIX rats were inoculated in the liver with syngeneic colon cancer cells DHD/K12/TRb to induce the development of subcapsular tumor nodules. Fourteen days post-inoculation, the animals were used for biodistribution studies. We evaluated a total of 11 administration protocols for the boron compounds boronophenylalanine (BPA) and GB-10 (Na(2)(10)B(10)H(10)), alone or combined at different dose levels and employing different administration routes. Tumor, normal tissue, and blood samples were processed for boron measurement by atomic emission spectroscopy. Six protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue. Boron concentration values in tumor and normal tissues in the liver metastases model show it would be feasible to reach therapeutic BNCT doses in tumor without exceeding radiotolerance in normal tissue at the thermal neutron facility at RA-3. PMID:21132507

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

2010-12-05

387

Boronated carbohydrate derivatives as potential boron neutron capture therapy reagents.  

PubMed

The treatment of cancer remains one of the most challenging problems for humanity. Boron neutron capture therapy is a binary approach for cancer treatment that is particularly attractive in treating high-grade gliomas and metastatic brain tumors. Among the types of boron-containing molecules used as boron neutron capture therapy agents, boronated carbohydrate derivatives have received significant attention because of their preferential uptake by growing tumor cells. This review provides a summary of the recent developments in the chemistry of carborane-containing carbohydrates. PMID:23617431

Marepally, Srinivasa R; Yao, Min-Liang; Kabalka, George W

2013-04-01

388

Concentrations, sources and spatial distribution of polycyclic aromatic hydrocarbons in soils from Beijing, Tianjin and surrounding areas, North China  

PubMed Central

The concentrations, profiles, sources and spatial distribution of polycyclic aromatic hydrocarbons (PAHs) were determined in 40 surface soil samples collected from Beijing, Tianjin and surrounding areas, North China in 2007, and all sampling sites were far from industrial areas, roadsides and other pollution sources, and across a range of soil types in remote, rural villages and urban areas. The total concentrations of 16 PAHs ranged from 31.6 to 1475.0 ng/g, with an arithmetic average of 336.4 ng/g. The highest PAH concentrations were measured in urban soils, followed by rural village soils and soils from remote locations. The remote–rural village–urban PAH concentration gradient was related to population density, gross domestic product (GDP), long-range atmospheric transport and different types of land use. In addition, the PAH concentration was well correlated with the total organic carbon (TOC) concentration of the soil. The PAH profile suggested that coal combustion and biomass burning were primary PAH sources.

Wang, Wentao; Massey Simonich, Staci L.; Xue, Miao; Zhao, Jingyu; Zhang, Na; Wang, Rong; Cao, Jun; Tao, Shu

2013-01-01

389

Upper ocean vertical supply: A neglected primary factor controlling the distribution of neodymium concentrations of open ocean surface waters?  

NASA Astrophysics Data System (ADS)

Neodymium (Nd) isotopes are an important geochemical tool to trace the present and past water mass mixing as well as continental inputs. The distribution of Nd concentrations in open ocean surface waters (0-100 m) is generally assumed to be controlled by lateral mixing of Nd from coastal surface currents and by removal through reversible particle scavenging. However, using 228Ra activity as an indicator of coastal water mass influence, surface water Nd concentration data available on key oceanic transects as a whole do not support the above scenario. From a global compilation of available data, we find that more stratified regions are generally associated with low surface Nd concentrations. This implies that upper ocean vertical supply may be an as yet neglected primary factor in determining the basin-scale variations of surface water Nd concentrations. Similar to the mechanism of nutrients supply, it is likely that stratification inhibits vertical supply of Nd from the subsurface thermocline waters and thus the magnitude of Nd flux to the surface layer. Consistently, the estimated required input flux of Nd to the surface layer to maintain the observed concentrations could be nearly two orders of magnitudes larger than riverine/dust flux, and also larger than the model-based estimation on shelf-derived coastal flux. In addition, preliminary results from modeling experiments reveal that the input from shallow boundary sources, riverine input, and release from dust are actually not the primary factors controlling Nd concentrations most notably in the Pacific and Southern Ocean surface waters.

Chen, Tian-Yu; Rempfer, Johannes; Frank, Martin; Stumpf, Roland; Molina-Kescher, Mario

2013-08-01

390

Experimental Microbiology of Saturated Salt Solutions and Other Harsh Environments. III. Growth of Salt-Tolerant Penicillium notatum in Boron-Rich Media 1  

PubMed Central

A stress-tolerant strain of Penicillium notatum, isolated by passage through a nutrient solution saturated with calcium acetate, was found to have a tolerance to boron in several states of oxidation. Growth in the presence of elementary boron, saturating amounts of boric acid, and with various concentrations of sodium borohydride was observed and mycelial mats were spectrographically analyzed for boron accumulation.

Roberts, Karen; Siegel, S. M.

1967-01-01

391

Use of species sensitivity distributions to predict no-effect concentrations of an antifouling biocide, pyridine triphenylborane, for marine organisms.  

PubMed

We used species sensitivity distributions (SSDs) and a Bayesian statistical model to carry out a primary risk assessment for pyridine triphenylborane (PTPB) in Hiroshima Bay, Japan. We used SSDs derived from toxicity values, such as EC?? and LC??, obtained from this study and previous work to calculate hazardous concentrations that should protect 95% and 99% of species (HC? and HC?) and demonstrated that the medians of the HC? and HC? were 0.78 and 0.17 ?g/L, respectively. We also used liquid chromatography/mass spectrometry to investigate the occurrence of PTPB in seawater from several coastal sites of Hiroshima Bay and detected PTPB at concentrations of 4.8-21 pg/L. Comparison of environmental concentrations to the HC values suggests that the current ecological risk posed by PTPB in Hiroshima Bay is low. This is the first report of the detection of PTPB in the natural marine environment. PMID:23044030

Mochida, Kazuhiko; Onduka, Toshimitsu; Amano, Haruna; Ito, Mana; Ito, Katsutoshi; Tanaka, Hiroyuki; Fujii, Kazunori

2012-10-06

392

[Analysis on concentration, distribution and budgets of Mn and Zn in soybean by using ICP-AES].  

PubMed

The concentration and distribution of Mn and Zn in soil and soybean in lower reach of Liaohe River Plain were investigated with ICP-AES analysis. The results showed that the available Zn in soils was close to the critical value and the monitoring should be strengthened. Zn concentration in seed and stalk, coupled with Mn in stalk, was not affected by fertilization types, while Mn concentration in seed under NPK and NPKO treatments was significantly higher than that with O and CK treatments. Application of organic and inorganic fertilizer increased crop biomass, and consequently increased Mn and Zn storage in soybean. In soil-crop system, Mn and Zn under different fertilization regimes showed budget deficit, with the deficit order of NPKO < O < CK < NPK, indicating that nutrient cycling could decrease the deficit significantly and keep the ecological systems more sustainable. PMID:23841439

Zhou, Hua; Jiang, Chun-Ming; Xu, Yong-Gang; Ma, Qiang

2013-04-01

393

Boron Determination—A Review of Analytical Methods  

Microsoft Academic Search

This paper reviews published methods of sample preparation, determinand purification, and the determination of boron concentration and isotopic composition in a sample. The most common methods for the determination of B concentration are spectrophotometric and plasma-source spectrometric methods. Although most spectrophotometric methods are based on colorimetric reactions of B with azomethine-H, curcumin, or carmine, other colorimetric and fluorometric methods have

R. N. Sah; P. H. Brown

1997-01-01

394

In vitro approach to study the influence of the cardiac output distribution on drug concentration  

Microsoft Academic Search

Summary  Blood flow is not constant during the day, not only due to cardiac output variation but to the variable blood flow fraction\\u000a supplied to the organs. To what extent these variations could affect the relative drug concentration between two different\\u000a tissues, is the purpose of this work. In order to study that, a device was designed which took into account

P. Fagiolino; F. Wilson; E. Samaniego; M. Vázquez

2003-01-01

395

CFD-DEM Study of Temperature and Concentration Distribution in a Polyethylene Fluidized Bed Reactor  

Microsoft Academic Search

Comprehensive modeling of the gas-phase polyethylene reactor was developed by combining discrete element method (for predicting motion of particulates), Navier-Stokes equation (for predicting velocity fields of gas phase), mass conservation equation (for predicting concentration of reactants), and energy conservation equation (for predicting temperature). A comprehensive kinetic mechanism was used to evaluate the rate of ethylene and 1-butene copolymerization reactions. Simultaneous

Sedigheh Karimi; Zahra Mansourpour; Navid Mostoufi; Rahmat Sotudeh-Gharebagh

2011-01-01

396

Caenorhabditis elegans Maintains Highly Compartmentalized Cellular Distribution of Metals and Steep Concentration Gradients of Manganese  

PubMed Central

Bioinorganic chemistry is critical to cellular function. Homeostasis of manganese (Mn), for example, is essential for life. A lack of methods for direct in situ visualization of Mn and other biological metals within intact multicellular eukaryotes limits our understanding of management of these metals. We provide the first quantitative subcellular visualization of endogenous Mn concentrations (spanning two orders of magnitude) associated with individual cells of the nematode, Caenorhabditis elegans.

Mayo, Sheridan; Howard, Daryl L.; Ryan, Christopher G.; Kirkham, Robin; Moorhead, Gareth F.; Paterson, David; de Jonge, Martin D.; Bush, Ashley I.

2012-01-01

397

The concentration of commercial success in popular music: An analysis of the distribution of gold records  

Microsoft Academic Search

This paper examines whether commercial success in the popular recorded-music industry, as measured by gold-record output, conforms to an empirical concentration. We find that Lotka's Law overestimates the number of artists with one gold record and underestimates the number of multiplegold-record performing artists. However, for all measures of “successful” records, theGeneralized Lotka's Law provides an excellent fit, which suggests that

Raymond A. K. Cox; James M. Felton; Kee H. Chung

1995-01-01

398

Distribution of aquatic yeasts — Effect of incubation temperature and chloramphenicol concentration on isolation  

Microsoft Academic Search

Fresh (river), estuarine, and marine waters in and along the coastline of Connecticut were cultured by the membrane filter technique at 20 and 37°C on a complex medium containing 0–1000 mg\\/L of chloramphenicol. Using counts on medium with 500 mg\\/L antibiotic as a base, ratios of total and pink yeast counts were recorded for other chloramphenicol concentrations at both temperatures

John D. Buck

1975-01-01

399

Concentration level and distribution of polycyclic aromatic hydrocarbons in soil and grass around Mt. Qomolangma, China  

Microsoft Academic Search

High mountains may serve as a condenser for persistent organic pollutants. In the present study, soil and grass samples from\\u000a Mt. Qomolangma region, China were collected from 4600 to 5620 m a.s.l and were analyzed for polycyclic aromatic hydrocarbons\\u000a (PAHs) to determine if they are concentrated at colder, more elevated sites and to evaluate their possible resources and fractionation.\\u000a The

XiaoPing Wang; TanDong Yao; ZhiYuan Cong; XinLiang Yan; ShiChang Kang; Yong Zhang

2007-01-01

400

Urban aerosol particulates on Hong Kong roadsides: size distribution and concentration levels with time  

Microsoft Academic Search

A detailed study on particulate matter from vehicle emission was carried out at roadsides in Hong Kong downtown area. The\\u000a study aims to explore the variations of particulate matter at roadsides in morning and afternoon. Data of concentrations of\\u000a different size groups of particulate matter were collected and analyzed. It was found that the particulate levels generally\\u000a vary periodically with

He Hong-di; Lu Wei-Zhen

401

Chemical composition of arctic snow: concentration levels and regional distribution of major elements  

Microsoft Academic Search

At the end of the northern winter 1996\\/1997, 21 snow samples were collected from 17 arctic localities in Norway, Sweden, Finland, Svalbard, Russia, Alaska, Canada, Greenland and Iceland. Major element concentrations of the filtered (0.45 ?m) melted snow indicate that most samples are consistent with a diluted seawater composition. Deviations from this behaviour indicate additional SO42? and Cl? relative to

Patrice de Caritat; Gwendy Hall; William Belsey; Marlene Braun; Natalia I. Goloubeva; Hans Kristian Olsen; Jon Ove Scheie; Judy E. Vaive

2005-01-01

402

Sensitivity of the Global Distribution of Cirrus Ice Crystal Concentration to Heterogeneous Freezing (Invited)  

NASA Astrophysics Data System (ADS)

This study presents the sensitivity of global ice crystal number concentration, Nc, to the parameterization of heterogeneous ice nuclei (IN). Simulations are carried out with the NASA Global Modeling Initiative (GMI) chemical and transport model coupled to an analytical ice microphysics parameterization. Heterogeneous freezing is described using nucleation spectra derived from theoretical and empirical considerations, considering dust, black carbon, ammonium sulfate, and glassy aerosol as IN precursors. When competition between homogeneous and heterogeneous freezing is considered, global mean Nc vary by up to a factor of twenty depending on the heterogeneous freezing spectrum used. IN effects on Nc strongly depend on dust and black carbon concentrations, and are strongest under conditions of weak updraft and high temperature. Regardless of the heterogeneous spectrum used, dust is an important contributor of IN over large regions of the northern hemisphere. Black carbon however exhibits appreciable effects on when the freezing fraction is greater than 1%. Compared to in situ observations, Nc is overpredicted at temperatures below 205 K, even if a fraction of liquid aerosol is allowed to act as glassy IN. Assuming that cirrus formation is forced by weak updraft addressed this overprediction but promoted heterogeneous freezing effects to the point where homogeneous freezing is inhibited even for IN concentrations as low as 1 L-1. Chemistry and dynamics must be considered to explain cirrus characteristics at low temperature. Only cloud formation scenarios where competition between homogeneous and heterogeneous freezing is the dominant feature would result in maximum supersaturation levels consistent with observations.

Nenes, A.; Barahona, D.; Rodriguez, J. M.

2010-12-01

403

The distribution of serum folate concentration and red blood cell indices in alcoholics.  

PubMed

Chronic alcohol consumption leads to malnutrition and to the deficiency of many vitamins. One of the most important is folate deficiency. Folate deficiency disrupts the process of hematopoiesis, which can be evaluated by the changes of red cell indices. The aim of this study was to determine the hematological disturbances by the measurement of red blood cell indices in a Polish population of chronic alcoholics according to folate status. We studied 80 consecutive chronic alcoholic men and 30 healthy controls. Patients were divided into 2 groups according to the folate concentration. The serum folate and vitamin B12 concentration and the blood count were determined. We have shown that the serum folate concentration was decreased in 40% of alcoholics, but there was no folate deficiency and the level of vitamin B12 was normal. There was no correlation between folate, vitamin B12 and hematological indices. We have observed that most hematological parameters (Hb, RBCs, and Hct) in alcoholics were decreased and only two of them (MCV and MCHC) were increased in comparison with the controls. We observed no significant correlation between the RBCs indices and the weekly alcohol intake, but the correlation between RBCs, Hb, Hct and the duration of dependence have been shown. We concluded that, there is no folate deficiency in the Polish alcoholic population but the abusers with low folate levels may already have some RBCs indices affected. It means that the Polish alcoholic population consumes a sufficient amount of vitamins, which prevents the occurrence of hematological disturbances. PMID:23535533

Cylwik, Bogdan; Naklicki, Marcin; Gruszewska, Ewa; Szmitkowski, Maciej; Chrostek, Lech

2013-01-01

404

Distribution of Elevated Nitrate Concentrations in Ground Water in Washington State  

USGS Publications Warehouse

More than 60 percent of the population of Washington State uses ground water for their drinking and cooking needs. Nitrate concentrations in ground water are elevated in parts of the State as a result of various land-use practices, including fertilizer application, dairy operations and ranching, and septic-system use. Shallow wells generally are more vulnerable to nitrate contamination than deeper wells (Williamson and others, 1998; Ebbert and others, 2000). In order to protect public health, the Washington State Department of Health requires that public water systems regularly measure nitrate in their wells. Public water systems serving more than 25 people collect water samples at least annually; systems serving from 2 to 14 people collect water samples at least every 3 years. Private well owners serving one residence may be required to sample when the well is first drilled, but are unregulated after that. As a result, limited information is available to citizens and public health officials about potential exposure to elevated nitrate concentrations for people whose primary drinking-water sources are private wells. The U.S. Geological Survey and Washington State Department of Health collaborated to examine water-quality data from public water systems and develop models that calculate the probability of detecting elevated nitrate concentrations in ground water. Maps were then developed to estimate ground water vulnerability to nitrate in areas where limited data are available.

Frans, Lonna

2008-01-01

405

Sampling and analysis of chemical element concentration distribution in rock units and orebodies  

NASA Astrophysics Data System (ADS)

Existing sampling techniques applied within known orebodies, such as sampling along mining drifts, yield element concentration values for larger blocks of ore if they are extended into their surroundings. The resulting average concentration values have relatively small "extension variance". These techniques can be used for multifractal modeling as well as ore reserve estimation approaches. Geometric probability theory can aid in local spatial covariance modeling. It provides information about increase of variability of element concentration over short distances exceeding microscopic scale. In general, the local clustering of ore crystals results in small-scale variability known as the "nugget effect". Parameters to characterize spatial covariance estimated from ore samples subjected to chemical analysis for ore reserve estimation may not be valid at local scale because of the nugget effect. The novel method of local singularity mapping applied within orebodies provides new insights into the nature of the nugget effect. Within the Pulacayo orebody, Bolivia, local singularity for zinc is linearly related with logarithmically transformed concentration value. If there is a nugget effect, moving averages resulting from covariance models or estimated by other methods that have a smoothing effect, such as kriging, can be improved by incorporating local singularities indicating local element enrichment or depletion. Although there have been many successful applications of the multifractal binomial/p model, its application within the Pulacayo orebody results in inconsistencies, indicating some shortcomings of this relatively simple approach. Local singularity analysis and universal multifractal modeling are two promising new approaches to improve upon results obtained by commonly used geostatistical techniques and use of the binomial/p model. All methods in this paper are illustrated using a single example (118 Pulacayo zinc values), and several techniques are applied to other orebody datasets (Whalesback copper deposit, Witwatersrand goldfields and Black Cargo titanium deposit). Additionally, it is discussed that nugget effects exist in a binary series of alternating mostly gneiss and metabasite previously derived from KTB borehole velocity and lithology logs, and within a series of 2796 copper concentration values from this same drill-hole.

Agterberg, F. P.

2012-01-01

406

Measurements of the distribution of adenylate concentrations and adenylate energy charge across Pseudomonas aeruginosa biofilms.  

PubMed Central

Adenine nucleotide pools and adenylate energy charge distributions were determined by using a laboratory-generated quasi-steady-state Pseudomonas aeruginosa biofilm. The method used involved freezing and sectioning of the intact biofilm, followed by extraction and assay of the adenylates in the sectioned material. Results indicated an increase in adenylate energy charge of about 0.2 units from the bottom to the surface of the biofilm. However, energy charge values were generally low throughout the biofilm, reaching a maximum of only 0.6 units. Of the adenylates measured, AMP was the predominant nucleotide, especially in the deeper parts of the biofilm profile.

Kinniment, S L; Wimpenny, J W

1992-01-01

407

Boron enhancement of high LET Cf-252 brachytherapy in the brain  

SciTech Connect

The authors have investigated the potential enhancement in dose distribution and cell killing effectiveness for Cf-252 brain implants by the addition of boron-10 enriched boron compounds which cross the blood brain barrier. There is a significant enhancement in both the absorbed dose and the high LET event frequency at distances of 3-5 cm from the sources. The principal difficulty, aside from toxicity and delivery problems, is a tendency for the thermal neutron distribution to peak at the center of the head instead of centering on the source distribution. The increase in cell killing was found to closely parallel the increase in absorbed dose from the boron capture events.

Beach, J.L.; Ashtari, M.; Harris, M.R.

1986-01-01

408

Air pollutants in rural homes in Guizhou, China - Concentrations, speciation, and size distribution  

NASA Astrophysics Data System (ADS)

Several types of fuels, including coal, fuel wood, and biogas, are commonly used for cooking and heating in Chinese rural households, resulting in indoor air pollution and causing severe health impacts. In this paper, we report a study monitoring multiple pollutants including PM 10, PM 2.5, CO, CO 2, and volatile organic compounds (VOCs) from fuel combustion at households in Guizhou province of China. The results showed that most pollutants exhibited large variability for different type of fuels except for CO 2. Among these fuels, wood combustion caused the most serious indoor air pollution, with the highest concentrations of particulate matters (218˜417 ?g m -3 for PM 10 and 201˜304 ?g m -3 for PM 2.5), and higher concentrations of CO (10.8 ± 0.8 mg m -3) and TVOC (about 466.7 ± 337.9 ?g m -3). Coal combustion also resulted in higher concentrations of particulate matters (220˜250 ?g m -3 for PM 10 and 170˜200 ?g m -3 for PM 2.5), but different levels for CO (respectively 14.5 ± 3.7 mg m -3 for combustion in brick stove and 5.5 ± 0.7 mg m -3 for combustion in metal stove) and TVOC (170 mg m -3 for combustion in brick stove and 700 mg m -3 for combustion in metal stove). Biogas was the cleanest fuel, which brought about the similar levels of various pollutants with the indoor case of non-combustion, and worth being promoted in more areas. Analysis of the chemical profiles of PM 2.5 indicated that OC and EC were dominant components for all fuels, with the proportions of 30˜48%. A high fraction of SO 42- (31˜34%) was detected for coal combustion. The cumulative percentages of these chemical species were within the range of 0.7˜1.3, which was acceptable for the assessment of mass balance.

Wang, Shuxiao; Wei, Wei; Li, Du; Aunan, Kristin; Hao, Jiming

2010-11-01

409

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

410

Boron deficiency in maize  

Microsoft Academic Search

Boron (B) deficiency depresses wheat, barley and triticale yield through male sterility. On the basis of field responses to\\u000a B fertilization, maize (Zea mays L.) is affected by B deficiency in five continents. In a series of sand culture trials with maize subject to B0 (nil added\\u000a B) and B20 (20 ?M added B) treatments, we described how B deficiency depressed

Sittichai Lordkaew; Bernard Dell; Sansanee Jamjod; Benjavan Rerkasem

2011-01-01

411

Natural Radioactivity of Boron Added Clay Samples  

NASA Astrophysics Data System (ADS)

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

Akkurt, I.; Çanakci?, H.; Mavi, B.; Güno?lu, K.

2011-12-01

412

Natural Radioactivity of Boron Added Clay Samples  

SciTech Connect

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

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

2011-12-26

413

Precipitation of boron in silicon on high-dose implantation  

SciTech Connect

Precipitation of boron implanted in silicon with a dose of 1 x 10{sup 16} cm{sup -2} is studied in relation to the concentration of substitutional boron C{sub B{sub 0}} introduced before implantation and before subsequent annealing at 900 deg. C. It is shown that C{sub B{sub 0}} = 2.5 x 10{sup 20} cm{sup -3} is the critical concentration, at which the formation of precipitates is independent of the concentration of point defects introduced by implantation (far from or close to the mean projected range R{sub p}) and constitutes the prevailing channel of deactivation of boron. At lower concentrations C{sub B{sub 0}} close to the equilibrium concentration, precipitation is observed only far from R{sub p}, in the regions of reduced concentrations of point defects. At the same time, in the region of R{sub p} with a high concentration of point defects, most boron atoms are drawn into clustering with intrinsic interstitial atoms with the formation of dislocation loops and, thus, become electrically inactive as well.

Feklistov, K. V., E-mail: kos@thermo.isp.nsc.ru; Fedina, L. I.; Cherkov, A. G. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Division (Russian Federation)

2010-03-15

414

Distribution of soluble uranium in the nuclear cell compartment at subtoxic concentrations.  

PubMed

Uranium is naturally found in the environment, and its extensive use results in an increased risk of human exposure. Kidney cells have mainly been used as in vitro models to study effects of uranium exposure, and very little about the effects on other cell types is known. The aim of this study was to assess the impact of depleted uranium exposure at the cellular level in human kidney (HEK-293), liver (HepG2), and neuronal (IMR-32) cell lines. Cytotoxicity studies showed that these cell lines reacted in a roughly similar manner to depleted uranium exposure, responding at a cytotoxicity threshold of 300-500 ?M. Uranium was localized in cells with secondary ion mass spectrometry technology. Results showed that uranium precipitates at subtoxic concentrations (>100 ?M). With this approach, we were able for the first time to observe the soluble form of uranium in the cell at low concentrations (10-100 ?M). Moreover, this technique allows us to localize it mainly in the nucleus. These innovative results raise the question of how uranium penetrates into cells and open new perspectives for studying the mechanisms of uranium chemical toxicity. PMID:21067124

Rouas, Caroline; Bensoussan, Helene; Suhard, David; Tessier, Christine; Grandcolas, Line; Rebiere, François; Dublineau, Isabelle; Taouis, Mohammed; Pallardy, Marc; Lestaevel, Philippe; Gueguen, Yann

2010-12-20

415

Nitrogen oxide abatement by distributed fuel addition. [Reburning, mixing, effect of concentration of nitrogen  

SciTech Connect

Reburning experiments are presented in which the effect of the primary flame mode is examined. The application of reburning downstream of an axial diffusion primary flame without swirl is compared to reburning results in which the primary flame is premixed. The comparison is qualitative and is intended to examine reburning under more realistic conditions of utility boilers, where premixed flames are not common. Experimental results of reburning tests using nitrogen containing reburning fuels (ammonia doped natural gas and coal) are presented. The effect of reburning fuel type and nitrogen content on nitrogenous species profiles in the reburn zone are discussed. The last section is concerned with the applications of the kinetic model to predict overall reburning effectiveness from the primary NO level and to identify configuration for low total fixed nitrogen concentration. The effects of mixing in the early stage of reburning are examined and appropriate corrections are incorporated with the kinetic model to allow the prediction of nitrogenous species concentrations in the region where mixing effects are important. An empirical correlation is used to estimate the conversion of the total fixed nitrogen in the reburn zone to NO in the final stage of reburning. The kinetic model is also applied to the testing of hypothetical fuel-rich configurations to identify kinetic limits that would prevent further reductions in nitrogenous species.

Wendt, J.O.L.; Mereb, J.B.

1991-01-02

416

3D Trace gas concentration distributions from groundbased and airborne tomographic DOAS measurements  

NASA Astrophysics Data System (ADS)

An overview on the AFO-2000 project "Tom-DOAS" is given. The project aims the assessment of concentration maps from DOAS measurements performed from ground or aircraft with more than ten light beams. 1) A first ground-based experiment was set up in April/May 2001 during the motorway campaign BABII (organised by Fiedler et al.): Two DOAS telescopes were directed onto eight retro reflector arrays mounted on two cranes, providing 16 light beams in total. From the data Luff and Lee profiles and the emission plumes of NO2 and ozone could be derived. 2) A new telescope type, the Multibeam telescope, was developed for the simultaneous measurement of multiple paths at ground. 3) An aircraft instrument was developed and about 20 flight hours of Tom-DOAS measurements were performed onboard a Partenavia aircraft in the Milano area (Italy) in the frame of the EU "FORMAT" project (July/August 2002) - in co-operation with the Institut für Umweltphysik of the University of Bremen 4) A new inversion software, "TOMOLAB", was developed, which converts the DOAS column data to concentration maps. It is used for the optimisation of tomographic setups using model data, e.g. for flight track choices, as well as for the inversion of real data sets from the measurements.

Pundt, I.; Hak, C.; Hartl, A.; Heue, K.-P.; Knab, V.; Kunz, C.; Laepple, T.; Lee, W.-D.; Mettendorf, K. U.; Sun, H.

2003-04-01

417

Quantitative reconstruction of refractive index distribution and imaging of glucose concentration by using diffusing light  

NASA Astrophysics Data System (ADS)

We show that a two-step reconstruction method can be adapted to improve the quantitative accuracy of the refractive index reconstruction in phase-contrast diffuse optical tomography (PCDOT). We also describe the possibility of imaging tissue glucose concentration with PCDOT. In this two-step method, we first use our existing finite-element reconstruction algorithm to recover the position and shape of a target. We then use the position and size of the target as a priori information to reconstruct a single value of the refractive index within the target and background regions using a region reconstruction method. Due to the extremely low contrast available in the refractive index reconstruction, we incorporate a data normalization scheme into the two-step reconstruction to combat the associated low signal-to-noise ratio. Through a series of phantom experiments we find that this two-step reconstruction method can considerably improve the quantitative accuracy of the refractive index reconstruction. The results show that the relative error of the reconstructed refractive index is reduced from 20% to within 1.5%. We also demonstrate the possibility of PCDOT for recovering glucose concentration using these phantom experiments.

Liang, Xiaoping; Zhang, Qizhi; Jiang, Huabei

2006-11-01

418

Distribution of BPA and metabolic assessment in glioblastoma patients during BNCT treatment: a microdialysis study  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) is dependent on the selective accumulation of boron-10 in tumour cells. To maximise the radiation effect, the neutrons should be delivered when the ratio between the boron concentration in tumour cells to that in normal tissues reaches maximum. However, the pharmacokinetics of p-boronophenylalanine (BPA) and other boron delivery agents are only partly known. We used

A. Tommy Bergenheim; Jacek Capala; Michael Roslin; Roger Henriksson

2005-01-01

419

[Size distributions and diurnal variations in the concentrations of polycyclic aromatic hydrocarbons in winter in urban and suburban Nanjing, China].  

PubMed

The contamination status and distribution characteristics of particulate polycyclic aromatic hydrocarbons (PAHs) were investigated in aerosols of urban and suburban Nanjing. A total of 17 PAHs were analyzed in the aerosol samples collected in daytime and nighttime during January 1st to 10th, 2010 in Nanjing University (NU) and Nanjing University of Information Science & Technology (NUIST). The PAH concentrations at the urban and suburban sites were 41.36-220.35 ng x m(-3) and 45.10-200.86 ng x m(-3), respectively, of which about 66%-67% was absorbed by fine particles (Dp < or = 2.1 microm). High levels of particulate PAHs were detected at both sampling sites with different diurnal variations. The higher total-PAH concentration occurred in the daytime at the urban site and in the nighttime at the suburban site. The change of prevailing wind direction and high-pressure weather system had significant impact on the variation of PAH concentrations, which were dominated by fine and coarse particles in urban and suburban regions, respectively. Difference in PAH size distributions was found for low weight molecular PAHs (LWM-PAH) and high weight molecular PAHs (HWM-PAH) in urban and suburban areas. The concentrations of 2-3 ring PAHs were higher at the suburban site than those at the urban site, whereas larger amounts of 4-6 ring PAHs were found at the urban site than at the suburban site. The concentration peaks in coarse particle size of high-molecular-weight PAHs found in our study were larger than those in some of the previous studies, which might be due to the high carbon content in coarse particles in the atmosphere at our sites. Analysis of diagnostic ratios indicated that the PAHs particles at both two sites have the same sources, including combustion of coal and biomass, vehicular exhaust and suburban industrial emission. PMID:23002588

Zhang, Hong-Liang; Fan, Shu-Xian; Gu, Kai-Hua; Zhu, Bin; Fan, Yang; Zu, Fan; Li, Hong-Shuang; Meng, Qing-Zi; He, Jia-Bao

2012-07-01

420

40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution  

Code of Federal Regulations, 2013 CFR

...Mass Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution F Table F-4 to Subpart F of Part 53...Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm)...

2013-07-01

421

Characterization of Droplets and Vapor Concentration Distributions in Split-Injection Diesel Sprays by Processing UV and Visible Images  

NASA Astrophysics Data System (ADS)

Recent experimental studies have shown that with split injection strategy, the soot and NOx emissions from a diesel engine can be reduced significantly in comparison with a conventional non-split injection. To understand the mechanism of emissions reduction, it is essential to clarify the process of mixture formation in the diesel spray. For characterizing the droplets and vapor concentration distributions inside a fuel spray, a dual-wavelength laser absorption-scattering technique (LAS) was developed by using the 2nd harmonic (532nm) and the 4th harmonic (266nm) of an Nd: YAG laser and using dimethylnaphthalene as a test fuel. By applying the ultraviolet-visible LAS imaging technique, the distributions of droplets and vapor concentrations in the spray, which was injected into a high-temperature and high-pressure nitrogen ambient in a constant volume vessel by a common-rail diesel injection system, were measured and quantitatively analyzed. The effect of injection mass ratio of double-pulse injections on distributions of equivalence ratios of vapor and droplets in the sprays was examined.

Zhang, Yuyin; Nishida, Keiya; Yoshizaki, Takuo

422

Concentration, distribution, and bioavailability of mercury and methylmercury in sediments of Baltimore Harbor and Chesapeake Bay, Maryland, USA  

SciTech Connect

For the Chesapeake Bay, sediments in regions such as Baltimore Harbor have total mercury (Hg) concentrations that exceed environmental effects guidelines. However, fish concentrations do not appear elevated. Indeed, the factors controlling the transfer of sedimentary Hg, especially as monomethylmercury (MMHg), the most bioaccumulative form of Hg, to these aquatic organisms are poorly understood. To examine this, the authors have investigated the distribution and bioavailability of Hg and MMHg to benthic organisms in Baltimore harbor and the Chesapeake Bay, in Maryland, USA. The results discussed here show that sediment concentration for both total Hg and MMHg covaries with sediment organic content and that this parameter is a better predictor, for surface sediments, of concentration than iron content, acid volatile sulfide (AVS), or other factors. Furthermore, correlations between inorganic Hg and MMHg in benthic biota with sediment levels suggest that variation in the bioaccumulation factor (SBAF) for invertebrates is best explained in terms of sediment organic content. thus, the results from this study emphasize the importance of organic matter in regions removed from point source input in controlling both the concentration and bioavailability of MMHg to organisms. Because of the exponential nature of the SBAF/organic content relationship, there is a nonlinear organism response to MMHg in sediments that must be considered in any estimation of the toxic effect of sediment MMHg. Also, as a result of the decoupling between total Hg and MMHg concentration and bioavailability in surface sediments, any remediation evaluation of bioavailability and/or toxicity that is based only on total Hg concentration is unlikely to provide a reliable prediction.

Mason, R.P.; Lawrence, A.L.

1999-11-01

423

Method of fabricating boron containing coatings  

DOEpatents

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

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

1999-01-01

424

Boron and boron isotope systematics in the peralkaline Ilímaussaq intrusion (South Greenland) and its granitic country rocks: A record of magmatic and hydrothermal processes  

Microsoft Academic Search

Concentrations of boron in whole rocks and minerals of the peralkaline, 1.16Ga Ilímaussaq intrusion and its granitic country rocks (South Greenland) were analysed using secondary ion mass spectrometry (SIMS) and prompt gamma neutron activation (PGNAA) analysis. The intrusion consists of an early augite–syenite shell, a later alkali-granite sheet and still later nepheline syenites, which dominate the Complex. Boron concentrations are

Melanie Kaliwoda; Horst R. Marschall; Michael A. W. Marks; Thomas Ludwig; Rainer Altherr; Gregor Markl

2011-01-01

425

Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions  

NASA Astrophysics Data System (ADS)

The mass-particle size distributions (MSDs) of 9 elements in ground-based aerosol samples from dust storm (DS) and non-dust storm (N-DS) periods were determined for 12 sites in 9 major desert regions in northern China. The masses of the 9 elements (Al, Fe, K, Mg, Mn, Sc, Si, Sr and Ti) in the atmosphere were dominated by local mineral dust that averaged 270?g m-3, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the<10?m particles account for ~84% of the total dust mass over the deserts. Model-calculated ("100-step" method) dry deposition velocities (Vd) for the 9 dust-derived elements during N-DS periods ranged from 4.4 to 6.8cms-1, with a median value of 5.6cms-1. On the basis of a statistical relationship between D99% (the dust particle diameter corresponding to the uppermost 1% of the cumulative mass distribution) and Vd, one can also predict dry velocities, especially when D99% ranges from 30 to 70?m. This provides a simple way to reconstruct Vd for dust deposits (like aeolian loess sediments in the Loess Plateau). The estimated daily dry deposition fluxes were higher during DS vs. N-DS periods, but in most cases, the monthly averaged fluxes were mainly attributable to N-DS dust. Two regions with high dust loading and fluxes are identified: the "Western High-Dust Desert" and the "Northern High-Dust Desert", with Taklimakan Desert and Badain Juran Desert as their respective centers. These are energetic regions in which desert-air is actively exchanged, and these apparently are the major source areas for Asian dust.

Zhang, Xiao Y.; Arimoto, R.; Zhu, G. H.; Chen, T.; Zhang, G. Y.

1998-09-01

426

Impact of spectral irradiance distribution and temperature on the outdoor performance of concentrator photovoltaic system  

NASA Astrophysics Data System (ADS)

Multi-junction solar cell is designed to have considerable effect towards the solar spectrum distribution so that the maximum solar radiation could be absorbed hence, enhancing the energy conversion efficiency of the cell. Due to its application in CPV system, the system's characteristics are more sensitive to environmental factor in comparison to flat-plate PV system which commonly equipped with Si-based solar cell. In this paper, the impact of environmental factors i.e. average photon energy (APE) and temperature of solar cell (Tcell) towards the performance of the tracking type CPV system were discussed. A year data period of direct spectral irradiance, cell temperature, and power output which recorded from November 2010 to October 2011 at a CPV system power generator plant located at Miyazaki, Japan was used in this study. The result showed that most frequent condition during operation was at APE = 1.87+/-0.005eV, Tcell = 65+/-2.5°C with performance ratio of 83.9%. Furthermore, an equivalent circuit simulation of a CPV subsystem in module unit was conducted in order to investigate the influence of environmental factors towards the performance of the module.

Husna, Husyira Al; Shibata, Naoki; Sawano, Naoki; Ueno, Seiya; Ota, Yasuyuki; Minemoto, Takashi; Araki, Kenji; Nishioka, Kensuke

2013-09-01

427

Stress intensity factors for an internal or edge crack in a circular elastic disk subjected to concentrated or distributed loads  

NASA Astrophysics Data System (ADS)

Stress intensity factors for an internal or edge crack in a circular elastic disk subjected to concentrated or distributed loads are obtained using the singular integral equation technique. First, a solution for the uncracked case is obtained using the complex variable method, and then employing the superposition technique the crack problem is reduced to a perturbation problem. By integrating the dislocation solution along the crack, a singular integral equation is obtained, which in turn is solved numerically. The stress intensity factors are calculated for various crack geometries and loading conditions.

Xu, Y. L.; Delale, F.

1992-07-01

428

Determining the concentration and distribution of arsenic deposits in rock matrices and porous media by X-ray difference microtomography  

NASA Astrophysics Data System (ADS)

Synchrotron-based high resolution X-ray microtomography was used to characterize arsenic (As) deposits within porous media. The distribution of arsenic was determined using difference tomography, where the X-rays used to image the sample were selected to be just above and below the As absorption edge at 11,853 eV. The difference tomograms have background noise from other minerals contained in the sample, local variation of X-ray beam intensity, and electronic noise associated with the data acquisition process. Image processing filters, such as windowing or adaptive filters derived from the Fast Fourier Transform (FFT) method, were employed to reduce background noise in the tomograms and enhance information on the arsenic deposits. These errors are generally larger in difference tomography than in conventional X-ray microtomography because this method requires operating at very specific X-ray energies (i.e., an edge of the element of interest), and this constraint makes it very difficult to obtain optimal contrast for tomographic reconstruction. In particular, the signal-to-noise ratio is often low in difference tomograms of geological samples having high background X-ray absorption. The relationship between As concentration and difference image intensity was evaluated using well defined As samples prepared in the laboratory, along with As-rich sinter deposits from El Tatio hydrothermal field and fluvial sediments from the Loa River downstream of El Tatio. This relationship is non-linear because of interactions between the different sources of error in the construction of the difference tomograms. As a result, the difference tomography method is relatively insensitive to bulk As concentrations, and instead primarily provides information on the distribution of regions of the sample that have high As concentrations, such as As-rich particles, precipitates, or evaporite deposits. Tomographic 3D reconstructions of the porous media and of the aggregate structure thus provide an unique opportunity to observe the distribution and morphology of arsenic deposits within primary source formations and mixed fluvial sediments. This approach provides a useful method for obtaining 3D microstructural and chemical information in rock matrices, for investigating contaminant distributions within sedimentary deposits, and for assessing distributions of different mineral phases within biofilms and other organic material.

Peng, D.; Alsina, M.; Chen, C.; Keane, D.; Packman, A. I.; Gaillard, J.; Aubeneau, A. F.; Pasten, P. A.; Pizarro, G.

2009-12-01

429

Seasonal and spatial trends in particle number concentrations and size distributions at the children's health study sites in Southern California.  

PubMed

Continuous measurements of particle number (PN), particle mass (PM(10)) and gaseous copollutants (NO(x), CO and O3) were obtained at eight sites (urban, suburban and remote) in Southern California during years 2002 and 2003 in support of University of Southern California Children's Health Study. We report the spatial and temporal variation of PNs and size distributions within these sites. Higher average total PN concentrations are found in winter (November to February), compared to summer (July to September) and spring (March to June) in all urban sites. Contribution of local vehicular emissions is most evident in cooler months, whereas effects of long-range transport of particles are enhanced during warmer periods. The particle size profile is most represented by a combination of the spatial effects, for example, sources, atmospheric processes and meteorological conditions prevalent at each location. Afternoon periods in the warmer months are characterized by elevated number concentrations that either coincide or follow a peak in ozone concentrations, suggesting the formation of new particles by photochemistry. Results show no meaningful correlation between PN and mass, indicating that mass based standards may not be effective in controlling ultrafine particles. The study of the impact of the Union worker's strike at port of Long Beach in October 2002 revealed statistically significant increase in PN concentrations in the 60-200 nm range (P<0.001), which are indicative of contributions of emissions from the idling ships at the port. PMID:16077742

Singh, Manisha; Phuleria, Harish C; Bowers, Kenneth; Sioutas, Constantinos

2006-01-01

430

Elevated heavy metal concentrations in top soils of an Aegean island town (Greece): total and available forms, origin and distribution.  

PubMed

Elevated heavy metal concentrations in urban top soils are principal indicators of environmental pollution; however, relative data on the heavy metal status in soils of Greek island towns, that are regional administrative centers and popular tourist destinations, are missing. A survey was conducted to examine heavy metal concentrations in the urban soils of Ermoupolis, the capital of Syros island and of the prefecture of Cyclades complex in the Aegean Sea. Total (aqua-regia extracted) and available (DTPA extracted) concentrations of Cu, Pb, Zn, Ni, Cr, Sn and Fe were determined in top soil samples collected from green areas and open spaces of the town and in surface samples from inland reference soils of the island. Mean values for the aqua-regia extracted fraction of Cu, Pb and Zn were 117, 155 and 440 mg kg(-1) respectively, up to four times higher than the respective mean values of the reference soils. Enrichment factors (EFs) for these metals indicated high accumulation in the urban top soils and the available to total concentration ratio of Cu, Pb, Zn and Fe was higher for the urban compared to the reference soils, suggesting differences in metal sequestration, resulting in higher metal availability in the urban soils. GIS analysis was used to visualize the spatial distribution of EFs of the studied heavy metals. Factor Analysis and Cluster Analysis, applied to aqua-regia and DTPA data sets, adequately elucidated the origin of metals grouped under each factor or cluster. PMID:18431683

Massas, I; Ehaliotis, C; Gerontidis, S; Sarris, E

2008-04-23

431

Boron containing multilayer coatings and method of fabrication  

DOEpatents

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

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

1997-01-01

432

Combustion characteristics of boron nanoparticles  

Microsoft Academic Search

An experimental investigation of the combustion characteristics of boron nanoparticles in the post flame region of a flat flame burner has been conducted. Boron is attractive as a fuel or a fuel supplement in propellants and explosives due to its high heats of combustion on both a gravimetric and volumetric basis. A relatively large database exists for combustion characteristics of

Gregory Young; Kyle Sullivan; Michael R. Zachariah; Kenneth Yu

2009-01-01

433

Boron Clusters Come of Age  

ERIC Educational Resources Information Center

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

Grimes, Russell N.

2004-01-01

434

Azomethine H colorimetric method for determining dissolved boron in water  

USGS Publications Warehouse

An automated colorimetric method for determining dissolved boron in water is described. The boron is complexe