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Sample records for boron concentration distribution

  1. Neutron capture autoradiographic determination of 10B distributions and concentrations in biological samples for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Yanagie, Hironobu; Ogura, Koichi; Matsumoto, Toshio; Eriguchi, Masazumi; Kobayashi, Hisao

    1999-11-01

    It is necessary for effective boron neutron capture therapy (BNCT) to accumulate 10B atoms in the tumor cells. We prepared a cationic liposome entrapped 10B compound for the delivery system and examined the delivery capacity of 10B atoms to pancreatic cancer cell, AsPC-1, in vivo. It is required to achieve an accurate measurement of 10B distributions and concentrations in biological samples with a sensitivity in the ppm range for BNCT. We applied CR-39 (polyallyldiglycol carbonate) plastic track detectors to ?-autoradiographic measurements of the 10B biodistribution in sliced whole-body samples of mice. To selectively desensitize undesirable proton tracks, we applied PEW (KOH+C 2H 5OH+H 2O) solution to the etching of CR-39 detector. The subsequent use of an alpha-track radiographic image analysis system enabled a discrimination between alpha tracks and recoiled proton tracks by the track size selection method. This enabled us to estimate quantitatively the distributions of 10B concentrations within the tissue sections by comparing with suitable standards.

  2. Boron distribution in sintered silicon carbide

    SciTech Connect

    Carter, W.D.; Holloway, P.H. ); White, C.; Clausing, R. )

    1988-01-01

    Boron concentrations on intergranular and transgranular fracture areas in sintered SiC were measured; {alpha}-SiC grains oriented parallel to the fracture surface would fracture at the {alpha}-{beta} interphase boundary. Auger electron spectroscopy showed that boron does not segregate to these boundaries in sintered SiC. This conclusion was generalized to include the other types of SiC grain boundaries. The absence of boron at grain boundaries suggests that its role in sintering is not to enhance diffusion rates. Chemical reactions and free surface segregation, which may explain the increased densification of SiC when B is present, are discussed.

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

    SciTech Connect

    Sauerer, A.; Troll, G. )

    1990-01-01

    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.

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

    PubMed

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

    2012-06-01

    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

  5. Boron concentration measurement system for the Czech BNCT project

    NASA Astrophysics Data System (ADS)

    Honzátko, J.; Tomandl, I.

    2000-07-01

    In the framework of the Czech Boron Neutron Capture Therapy (BNCT) project a Prompt Gamma Ray Analysis (PGRA) facility for the determination of the boron concentration in biological samples was built at light-water reactor at Řež. The facility utilizes the beam of thermal neutrons from a neutron guide. The pure beam of thermal neutrons and background conditions enables the determination of 1 ppm with the reasonable statistical error 5% within 15 minutes.

  6. Concentrations of arsenic, antimony, and boron in steam and steam condensate at The Geysers, California

    USGS Publications Warehouse

    Smith, C.L.; Ficklin, W.H.; Thompson, J.M.

    1987-01-01

    Studies at The Geysers Geothermal Field, California indicate that under some circumstances elements that are transported in the vapor phase can become enriched in the liquid phase. Waters from two condensate traps (steam traps) on steam lines at The Geysers are enriched with arsenic, antimony, and boron compared to the concentrations of these elements in coexisting steam. Concentrations of boron in condensate-trap waters were as high as 160 mg/L, arsenic as high as 35 mg/L, and antimony as high as 200 ??g/L. Enrichment of arsenic, antimony, and boron is at least partially controlled by the partitioning of these elements into the liquid phase, according to their vapor-liquid distribution coefficients, after they are transported in steam. Several of the elements that are most soluble in steam, including arsenic and antimony, are part of the trace-element suite that characterizes precious-metal epithermal ore deposits. ?? 1987.

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

    NASA Technical Reports Server (NTRS)

    Fox, Thomas A.; Bogart, Donald

    1955-01-01

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

  8. Boron Concentration Model and Effects of Boron Holdup on Axial Offset Anomaly (AOA) in PWRs

    SciTech Connect

    Zhou, Dawei; Jones, Barclay G.

    2002-07-01

    A significant number of current PWRs are experiencing axial offset anomaly (AOA), a condition that continues to elude prediction and thus creates an operational difficulty of being unable to accurately estimate safety margin. The cause of AOA is complex, involving both thermal-hydraulics and chemistry of core operation and design. This paper considers the structure of crud layers, which lead to AOA, and presents a thermal performance and neutron absorber concentration model for the crud layer that satisfactorily predicts the amount of boron accumulated to match that required to cause the observed power shifts. (authors)

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

    PubMed

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

    2015-04-01

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

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

    PubMed Central

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

    2015-01-01

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

  11. Boron

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron is an essential micronutrient element required for plant growth. Boron deficiency is wide-spread in crop plants throughout the world especially in coarse-textured soils in humid areas. Boron toxicity can also occur, especially in arid regions under irrigation. Plants respond directly to the...

  12. Reprint of Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina).

    PubMed

    Portu, Agustina; Postuma, Ian; Gadan, Mario Alberto; Saint Martin, Gisela; Olivera, Mara Silvina; Altieri, Saverio; Protti, Nicoletta; Bortolussi, Silva

    2015-12-01

    An inter-comparison of three boron determination techniques was carried out between laboratories from INFN-University of Pavia (Italy) and CNEA (Argentina): alpha spectrometry (alpha-spect), neutron capture radiography (NCR) and quantitative autoradiography (QTA). Samples of different nature were analysed: liquid standards, liver homogenates and tissue samples from different treatment protocols. The techniques showed a good agreement in a concentration range of interest in BNCT (1-100 ppm), thus demonstrating their applicability as precise methods to quantify boron and determine its distribution in tissues. PMID:26508276

  13. Inter-comparison of boron concentration measurements at INFN-University of Pavia (Italy) and CNEA (Argentina).

    PubMed

    Portu, Agustina; Postuma, Ian; Gadan, Mario Alberto; Saint Martin, Gisela; Olivera, Mara Silvina; Altieri, Saverio; Protti, Nicoletta; Bortolussi, Silva

    2015-11-01

    An inter-comparison of three boron determination techniques was carried out between laboratories from INFN-University of Pavia (Italy) and CNEA (Argentina): alpha spectrometry (alpha-spect), neutron capture radiography (NCR) and quantitative autoradiography (QTA). Samples of different nature were analysed: liquid standards, liver homogenates and tissue samples from different treatment protocols. The techniques showed a good agreement in a concentration range of interest in BNCT (1-100ppm), thus demonstrating their applicability as precise methods to quantify boron and determine its distribution in tissues. PMID:26454177

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

    SciTech Connect

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

    1986-02-01

    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.

  15. Boron

    MedlinePlus

    ... form of boron, inside the vagina to treat yeast infections. People also apply boric acid to the ... acid, used inside the vagina, can successfully treat yeast infections (candidiasis), including infections that do not seem ...

  16. CAN BROCCOLI TOLERATE HIGHER CONCENTRATIONS OF BORON UNDER SALINE CONDITIONS?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reuse of saline drainage water is a management option that is necessary for reducing the volume of drainage water produced on the west side of California's San Joaquin Valley (SJV). A potential limitation in implementing a drainage water reuse system is determining the extent by which boron, a natur...

  17. 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 ...

  18. Determination of boron concentration in oilfield water with a microfluidic ion exchange resin instrument.

    PubMed

    Floquet, Cedric F A; Sieben, Vincent J; MacKay, Bruce A; Mostowfi, Farshid

    2016-07-01

    We developed and validated a microfluidic instrument for interference-free determination of boron in produced water. The instrument uses a boron-specific chelating resin to separate the analyte from its complex matrix. Ten produced water samples were analyzed with the instrument and the results were successfully validated against ICP-MS measurements. Removing interference effects enables precise boron measurement for wastewater even with high total dissolved solid (TDS) levels. 1,4-Piperazinediethanesulfonic acid conditions the resin and maintains the optimum pH for boron adsorption from the sample. Boron is then eluted from the resin using a 10% sulfuric acid solution and its concentration measured with the colorimetric carminic acid assay in 95% sulfuric acid. The use of a microfluidic mixer greatly enhances the sensitivity and kinetics of the carminic acid assay, by factors of 2 and 7.5, respectively, when compared against the same assay performed manually. A maximum sensitivity of 2.5mg(-1)L, a precision of 4.2% over the 0-40.0mgL(-1) measuring range, a 0.3mgL(-1) limit of detection, and a sampling rate of up to four samples per hour were achieved. Automation and microfluidics reduce the operator workload and fluid manipulation errors, translating into safer and higher-quality measurements in the field. PMID:27154679

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

    SciTech Connect

    Subhash Chandra

    2008-05-30

    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.

  20. Boron distribution and the effect of lime on boron uptake by pansy, petunia, and gerbera plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reports of boron (B) deficiency have become more prevalent in pansy (Viola ×wittrockiana), petunia (Petunia ×hybrida), and gerbera (Gerbera jamesonii) plug production. When symptoms are observed in production the presence and severity of symptoms have no pattern, symptomatic plants can be located a...

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

    PubMed

    Liakopoulos, Georgios; Karabourniotis, George

    2005-03-01

    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

  2. Relationship Not Found Between Blood and Urine Concentrations and Body Mass Index in Humans With Apparently Adequate Boron Status.

    PubMed

    Koc, Fulya; Aysan, Erhan; Hasbahceci, Mustafa; Arpaci, Beyza; Gecer, Salih; Demirci, Selami; Sahin, Fikrettin

    2016-06-01

    The impact of boron on the development of obesity remains controversial in the analysis of experimental and clinical data. The objective of this study was to investigate the relationship between blood and urine boron concentrations and obesity in normal, overweight, obese, and morbidly obese subjects in different age groups. A total of 105 subjects were categorized into 12 groups based on body mass index and three different age levels: as young adult (18 to 34 years old), adult (35 to 54 years old), and older adult (greater than 55 years old). Age, gender, body mass index, and blood and urine boron concentrations were recorded for each subject. There were 50 women and 55 men, with a mean age of 44.63 ± 17.9 years. Blood and urine boron concentrations were similar among the groups (p = 0.510 and p = 0.228, respectively). However, a positive correlation between age and blood boron concentration (p = 0.001) was detected in contrast to the presence of a negative correlation between age and urine boron concentration (p = 0.027). Multiple linear regression analysis showed that there was no significant relationship between gender, age, and quantitative values of body mass index for each subject, and blood and urine boron concentrations. Although the relationship between boron and obesity has not been confirmed, changes of blood and urine boron concentrations with age may have some physiologic sequences to cause obesity. PMID:26458903

  3. 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

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

    2009-07-01

    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

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

    PubMed Central

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

    2015-01-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment. PMID:25940534

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

    PubMed

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

    2015-01-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment. PMID:25940534

  6. Improvement of depth dose distribution using multiple-field irradiation in boron neutron capture therapy.

    PubMed

    Fujimoto, N; Tanaka, H; Sakurai, Y; Takata, T; Kondo, N; Narabayashi, M; Nakagawa, Y; Watanabe, T; Kinashi, Y; Masunaga, S; Maruhashi, A; Ono, K; Suzuki, M

    2015-12-01

    It is important that improvements are made to depth dose distribution in boron neutron capture therapy, because the neutrons do not reach the innermost regions of the human body. Here, we evaluated the dose distribution obtained using multiple-field irradiation in simulation. From a dose volume histogram analysis, it was found that the mean and minimum tumor doses were increased using two-field irradiation, because of improved dose distribution for deeper-sited tumors. PMID:26282566

  7. Gabapentin concentrations and postmortem distribution.

    PubMed

    Hamm, Catherine E; Gary, Ray D; McIntyre, Iain M

    2016-05-01

    Gabapentin is a widely prescribed medication used primarily for the treatment of epilepsy and neuropathic pain. Gabapentin has a favorable adverse effect profile in therapeutic dosing with the most common reported effects being dizziness, fatigue, drowsiness, weight gain, and peripheral edema. Even with intentional self-poisonings, serious effects are generally rare. In this report, gabapentin analyses were performed on 30 postmortem cases that had peripheral blood, central blood and liver tissue. Overall the central to peripheral blood (C/P) ratio mean was 0.90±0.24 (mean±standard deviation), and a median of 0.97. The liver to peripheral blood (L/P) ratio mean was 0.68±0.26L/kg (mean±standard deviation), and a median of 0.65L/kg. An additional case, where both antemortem blood and postmortem peripheral blood specimens were available, revealed the same gabapentin concentration in both specimens. Taken together, the data presented suggests that gabapentin is unlikely to show postmortem redistribution. PMID:27038659

  8. Electroextraction of boron from boron carbide scrap

    SciTech Connect

    Jain, Ashish; Anthonysamy, S.; Ghosh, C.; Ravindran, T.R.; Divakar, R.; Mohandas, E.

    2013-10-15

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  11. BORON CONCENTRATIONS IN MILK FROM MOTHERS OF EXCLUSIVELY BREAST-FED HEALTHY FULL-TERM INFANTS ARE STABLE DURING THE FIRST FOUR MONTHS OF LACTATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 arch...

  12. Helium-3 and boron-10 concentration and depth measurements in alloys and semiconductors using NDP

    NASA Astrophysics Data System (ADS)

    Ünlü, Kenan; Saglam, Mehmet; Wehring, Bernard W.

    1999-02-01

    Neutron Depth Profiling (NDP) is a nondestructive near surface technique that is used to measure concentration versus absolute depth of several isotopes of light mass elements in various substrates. NDP is based on absorption reaction of thermal neutrons with the isotope of interest. Charged particles and recoil atoms are generated in the reaction. The depth profiles are determined by measuring the residual energy of the charged particles or the recoil atoms. The NDP technique has became an increasingly important method to measure depth profiles of 3He and 10B in alloys and semiconductor materials. A permanent NDP facility has been installed on the tangential beam port of the University of Texas (UT) TRIGA Mark-II research reactor. One of the standard applications of the UT-NDP facility involves the determination of boron profiles of borophosphosilicate glass (BPSG) samples. NDP is also being used in combination with electron microscopy measurements to determine radiation damage and microstructural changes in stainless steel samples. This is done to study the long-term effects of high-dose alpha irradiation for weapons grade plutonium encapsulation. Measurements of implanted boron-10 concentration and depth profiles of semiconductor materials in order to calibrate commercial implanters is another application at the UT-NDP facility. The concentration and depth profiles measured with NDP and SIMS are compared with reported data given by various vendors or different implanters in order to verify implant quality of semiconductor wafers. The results of the measurements and other possible applications of NDP are presented.

  13. Comparison of the level of boron concentrations in black teas with fruit teas available on the Polish market.

    PubMed

    Zioła-Frankowska, Anetta; Frankowski, Marcin; Novotny, Karel; Kanicky, Viktor

    2014-01-01

    The determination of boron by inductively coupled plasma-atomic emission spectrometry has been carried in water-soluble and acid soluble (total content) fractions of 36 samples of traditional black tea and fruit brew. The estimation of the impact of the type of tea on the concentration of boron in water-soluble and acid extracts and potential human health risk from the daily intake of boron was carried out in this study. The levels of boron differed significantly in black and fruit tea types. The mean total content of boron ranged from 8.31 to 18.40 mg/kg in black teas, from 12.85 to 15.13 mg/kg in black tea with fruit flavor, and from 12.09 to 22.77 mg/kg in fruit brews. The degree of extraction of boron in black tea ranged from 8% to 27% and for fruit tea from 17% to 69%. In addition, the values below 25% were of black teas with fruit flavors. The daily intake of B from tea infusions (three cups/day) is still within the average daily intake except for some of the fruit brews which exceed acceptable regulations of the daily intake of total boron by humans. Hence, it may not produce any health risks for human consumption, if other sources of metal contaminated food are not taken at the same time. PMID:25379551

  14. III 1 BORON

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron chemistry, analysis, environmental exposure, metabolism, anthropomorphic sources, beneficial physiological effects, and toxicity are reviewed. Boron is widely distributed in nature and always occurs bound to oxygen. Boron biochemistry is essentially that of boric acid, which forms ester comple...

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

    SciTech Connect

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

    1988-01-01

    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.

  16. Finding out the optimal boron concentration in BCx sheets for high capacity anode material in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Das, Deya; Hardikar, Rahul; Han, Sang Soo; Lee, Kwang Ryeol; Singh, Abhishek Kumar

    Boron doped graphene shows better adsorption of Li compared to pristine graphene and has been investigated as a potential anode material for Li-ion batteries. Using first principles density functional theory calculations, we investigate the effect of increasing boron concentration on the gravimetric capacity of mono-layered boron doped graphene sheets, BCx (x = 7, 5, 3, 2 and 1). Li storage capacity increases with the increase in boron concentration giving highest capacity for monolayer BC2 (~ 1400 mAh/g), and is about 1.6 times higher than previously reported capacity of BC3. This is due to the more number of available empty states above the Fermi level in BC2 compared to other sheets. Moreover, owing to a very low Li diffusion barrier, the Li kinetics in BC2 is also found to be better among all the layered boron doped carbon sheets. Further enhancement of B concentration, as in BC, leads to strong binding of Li, thereby hindering the delithiation processes. Hence, BC2 with optimal concentration of B among the BCx phases, emerges as a promising choice for anode material in rechargeable Li ion battery.

  17. Relationships between boron concentrations and trout in the Firehole River, Wyoming: historical information and preliminary results of a field study.

    PubMed

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

    1998-01-01

    The Firehole River (FHR) in Yellowstone National Park (YNP) is a world-renowned recreational fishery that predominantly includes rainbow trout (RBT, Oncorhynchus mykiss) and brown trout (BNT, Salmo trutta). The trout populations apparently are closed to immigration and have been self-sustaining since 1955. Inputs from hot springs and geysers increase the temperature and mineral content of the water, including elevating the boron (B) concentrations to a maximum of approximately 1 mg B/L. Both RBT and BNT reside in warm-water reaches, except when the water is extremely warm (> or = approximately 25 degrees C) during midsummer. They spawn in late fall and early winter, with documented spawning of BNT in the cold-water reach upstream from the Upper Geyser Basin and of RBT in the Lower Geyser Basin reach, where water temperatures presumably are the warmest; however, successful recruitment of RBT in waters containing approximately 1 mg B/L has not been demonstrated conclusively. Thus, we began investigating the relationships among temperature, B concentrations, other water-quality parameters, and the distribution and reproduction of trout in the FHR in spring 1997. However, atypical high water flows and concomitant lower than historical temperatures and B concentrations during summer 1997 preclude conclusions about avoidance of high B concentrations. PMID:10050918

  18. Relationships between Boron concentrations and trout in the firehole river, Wyoming: Historical information and preliminary results of a field study

    USGS Publications Warehouse

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

    1998-01-01

    The Firehole River (FHR) in Yellowstone National Park (YNP) is a world- renowned recreational fishery that predominantly includes rainbow trout (RBT, Oncorhynchus mykiss) and brown trout (BNT, Salmo trutta). The trout populations apparently are closed to immigration and have been self- sustaining since 1955. Inputs from hot springs and geysers increase the temperature and mineral content of the water, including elevating the boron (B) concentrations to a maximum of ~1 mg B/L. Both RBT and BNT reside in warm-water reaches, except when the water is extremely warm (???~25??C) during midsummer. They spawn in late fall and early winter, with documented spawning of BNT in the cold-water reach upstream from the Upper Geyser Basin and of RBT in the Lower Geyser Basin reach, where water temperatures presumably are the warmest; however, successful recruitment of RBT in waters containing ~1 mg B/L has not been demonstrated conclusively. Thus, we began investigating the relationships among temperature, B concentrations, other water-quality parameters, and the distribution and reproduction of trout in the FHR in spring 1997. However, atypical high water flows and concomitant lower than historical temperatures and B concentrations during summer 1997 preclude conclusions about avoidance of high B concentrations.

  19. Decreasing boron concentrations in UK rivers: insights into reductions in detergent formulations since the 1990s and within-catchment storage issues.

    PubMed

    Neal, Colin; Williams, Richard J; Bowes, Michael J; Harrass, Michael C; Neal, Margaret; Rowland, Philip; Wickham, Heather; Thacker, Sarah; Harman, Sarah; Vincent, Colin; Jarvie, Helen P

    2010-02-15

    The changing patterns of riverine boron concentration are examined for the Thames catchment in southern/southeastern England using data from 1997 to 2007. Boron concentrations are related to an independent marker for sewage effluent, sodium. The results show that boron concentrations in the main river channels have declined with time especially under baseflow conditions when sewage effluent dilution potential is at its lowest. While boron concentrations have reduced, especially under low-flow conditions, this does not fully translate to a corresponding reduction in boron flux and it seems that the "within-catchment" supplies of boron to the river are contaminated by urban sources. The estimated boron reduction in the effluent input to the river based on the changes in river chemistry is typically around 60% and this figure matches with an initial survey of more limited data for the industrial north of England. Data for effluent concentrations at eight sewage treatment works within the Kennet also indicate substantial reductions in boron concentrations: 80% reduction occurred between 2001 and 2008. For the more contaminated rivers there are issues of localised rather than catchment-wide sources and uncertainties over the extent and nature of water/boron stores. Atmospheric sources average around 32 to 61% for the cleaner and 4 to 14% for the more polluted parts. The substantial decreases in the boron concentrations correspond extremely well with the timing and extent of European wide trends for reductions in the industrial and domestic usage of boron-bearing compounds. It clearly indicates that such reductions have translated into lower average and peak concentrations of boron in the river although the full extent of these reductions has probably not yet occurred due to localised stores that are still to deplete. PMID:19932654

  20. Boron doping of diamond powder by enhanced diffusion and forced diffusion: Diffusion concentrations, mechanical, chemical and optical properties

    NASA Astrophysics Data System (ADS)

    Golshani, Fariborz

    Diamond, with its unique mechanical properties, is an excellent material for a wide range of applications. However, there exist some problems. One such problem is integration of diamond of diamond into tool's (usually tungsten-carbide) lattice matrix for the purpose of increasing its performance. The presence of cobalt in the matrix, which acts as a poison for diamond, causes graphitization and degradation of diamond. In addition, diamond graphitizes at sintering temperatures (1770 K). The results of this work suggest that boron has produced a protective layer for diamond, thus reducing the effects of annealing at high temperatures. Boron has been introduced into single crystal high pressure, high temperature diamond powder by enhanced diffusion and forced diffusion techniques. Enhanced diffusion resulted in higher concentrations of boron in diamond powder. Total boron concentrations of 500 to 600 ppm, and 10sp{20} cmsp{-3} at a depth of 0.5 micrometer, have been achieved. Hardness tests performed on doped samples reveal that diamond did not lose its strength due to diffusion at elevated temperatures. Raman spectroscopy and X-ray diffraction analysis did not show any change in the "quality" of diamond due to doping. Oxidation experiments performed on doped and undoped samples revealed that the samples with the highest boron concentrations had superior performance and resistance to oxidation. Final weight loss in these samples was much less than in undoped samples and samples with low boron concentrations. Scanning electron microscopy of these samples showed that degradation due to oxidation of heavily doped diamond samples was significantly less than other samples.

  1. Effect of boron concentration on recombination at the p-Si–Al{sub 2}O{sub 3} interface

    SciTech Connect

    Black, Lachlan E. Allen, Thomas; Cuevas, Andres; McIntosh, Keith R.

    2014-03-07

    We examine the surface passivation properties of Al{sub 2}O{sub 3} deposited on boron-doped planar 〈100〉 crystalline silicon surfaces as a function of the boron concentration. Both uniformly doped and diffused surfaces are studied, with surface boron concentrations ranging from 9.2 × 10{sup 15} to 5.2 × 10{sup 19} cm{sup −3}. Atmospheric pressure chemical vapor deposition and thermal atomic layer deposition are used to deposit the Al{sub 2}O{sub 3} films. The surface recombination rate of each sample is determined from photoconductance measurements together with the measured dopant profiles via numerical simulation, using the latest physical models. These values are compared with calculations based on the interface properties determined from capacitance–voltage and conductance measurements. It is found that the fundamental surface recombination velocity of electrons, S{sub n0}, which describes the chemical passivation of the interface, is independent of the surface boron concentration N{sub s} for N{sub s} ≤ 3 × 10{sup 19} cm{sup −3}, and in excellent agreement with values calculated from the interface state density D{sub it} and capture coefficients c{sub n} and c{sub p} measured on undiffused boron-doped surfaces. We conclude that the physical properties of the Si–Al{sub 2}O{sub 3} interface are independent of the boron dopant concentration over this range.

  2. Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial δ-doped diamond layers

    SciTech Connect

    Araújo, D.; Alegre, M. P.; Piñero, J. C.; Fiori, A.; Bustarret, E.; Jomard, F.

    2013-07-22

    To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 10{sup 20} cm{sup −3} were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p{sup −}/p{sup ++}/p{sup −} multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

  3. Boron dose determination for BNCT using Fricke and EPR dosimetry

    SciTech Connect

    Wielopolski, L.; Ciesielski, B.

    1995-02-01

    In Boron Neutron Capture Therapy (BNCT) the dominant dose delivered to the tumor is due to {alpha} and {sup 7}Li charged particles resulting from a neutron capture by {sup 10}B and is referred to herein as the boron dose. Boron dose is directly attributable to the following two independent factors, one boron concentration and the neutron capture energy dependent cross section of boron, and two the energy spectrum of the neutrons that interact with boron. The neutron energy distribution at a given point is dictated by the incident neutron energy distribution, the depth in tissue, geometrical factors such as beam size and patient`s dimensions. To account for these factors can be accommodated by using Monte Carlo theoretical simulations. However, in conventional experimental BNCT dosimetry, e.g., using TLDs or ionization chambers, it is only possible to estimate the boron dose. To overcome some of the limitations in the conventional dosimetry, modifications in ferrous sulfate dosimetry (Fricke) and Electron Paramagnetic Resonance (EPR) dosimetry in alanine, enable to measure specifically boron dose in a mixed gamma neutron radiation fields. The boron dose, in either of the dosimeters, is obtained as a difference between measurements with boronated and unboronated dosimeters. Since boron participates directly in the measurements, the boron dosimetry reflects the true contribution, integral of the neutron energy spectrum with boron cross section, of the boron dose to the total dose. Both methods are well established and used extensively in dosimetry, they are presented briefly here.

  4. Spatial and temporal distribution of specific conductance, boron, and phosphorus in a sewage-contaminated aquifer near Ashumet Pond, Cape Cod, Massachusetts

    USGS Publications Warehouse

    Bussey, K.W.; Walter, D.A.

    1996-01-01

    Spatial and temporal distributions of specific conductance, boron, and phosphorus were determined in a sewage-contaminated sand and gravel aquifer near Ashumet Pond, Cape Cod, Massachusetts. The source of contamination is secondarily treated sewage that has been discharged onto rapid- infiltration sand beds at the Massachusetts Military Reservation since 1936. Contaminated ground water containing as much as 2 milligrams per liter of dissolved phosphorus is discharging into Ashumet Pond, and there is concern that the continued discharge of phosphorus into the pond will accelerate eutrophication of the pond. Water-quality data collected from observation wells and multilevel samplers from June through July 1995 were used to delineate the spatial distributions of specific conductance, boron, and phosphorus. Temporal distributions were determined using sample-interval-weighted average concen- trations calculated from data collected in 1993, 1994, and 1995. Specific conductances were greater than 400 microsiemens per centimeter at 25C as far as 1,200 feet downgradient from the infiltration beds. Boron concentrations were greater than 400 micrograms per liter as far as 1,800 feet down- gradient from the beds and phosphorus concen- trations were greater than 3.0 milligrams per liter as far as 1,200 feet from the beds. Variability in distributions of specific conductance and boron concentrations is attributed to the history and distribution of sewage disposal onto the infiltration beds. The distribution of phosphorus concentrations also is related to the history and distribution of sewage disposal onto the beds but additional variability is caused by chemical interactions with the aquifer materials. Temporal changes in specific conductance and boron from 1993 to 1995 were negligible, except in the lower part of the plume (below an altitude of about 5 feet above sea level), where changes in weighted-average specific conductance were greater than 100 microsiemens per centimeter at 25C. Temporal changes in phosphorus generally were small except in the lower part of the plume, where weighted-average phosphorus concentrations decreased more than 1.3 milligrams per liter from 1993 to 1994. This decrease was accompanied by an increase in specific conductance. High concen- trations of phosphorus associated with low and moderate specific conductances possibly are the result of rapid phosphorus desorption in response to an influx of uncontaminated ground water. As a result of the cessation of sewage disposal in December 1995, clean, oxygenated water moving into contaminated parts of the aquifer may cause rapid desorption of sorbed phosphorus and temporarily result in high dissolved phosphorus concentrations in the aquifer.

  5. Effects of Dietary Cadmium and Boron Supplementation on Performance, Eggshell Quality and Mineral Concentrations of Bone in Laying Hens.

    PubMed

    Olgun, Osman; Bahtiyarca, Yilmaz

    2015-09-01

    This study was conducted to determine the effects of supplementation of different levels of cadmium and boron on performance, eggshell quality, and mineral concentrations of bone in layer diets. In this trial, a total of 144 layer chickens, 21 weeks old, were randomly divided into 12 experimental groups. In each experimental group, there were four replicates, and in each of the replicates, there were three hens. Experimental diets consisted of all possible combinations of four levels of added cadmium (0, 5, 15, and 45 mg/kg) and three levels of added boron (0, 60, and 120 mg/kg) to the basal diet. Added cadmium (15 or 45 mg/kg) had a significant adverse effect on performance parameters (P < 0.01). Eggshell thickness increased with the addition of 5 mg/kg level of cadmium to the diet (P < 0.01). Tibia cadmium content increased with the addition of cadmium and boron in the diet (P < 0.01). However, tibia boron content decreased with the supplementation of cadmium (P < 0.01). These results indicate that the addition of boron to the diet did not prevent adverse effect of cadmium on performance and eggshell quality, or accumulation of cadmium in bone. PMID:25749927

  6. Self-compensation property of β-rhombohedral boron doped with high Li concentration

    NASA Astrophysics Data System (ADS)

    Hyodo, H.; Nezu, A.; Soga, K.; Kimura, K.

    2012-11-01

    A high concentration of Li (up to LiB5.8; 18 Li/cell) was doped into β-rhombohedral boron (β-B), which has a crystalline structure built up from B12 icosahedral clusters, by sealing the raw materials in a stainless-steel tube. The relation between the structure and the electronic properties was clarified and a self-compensation property of Li- or Mg-doped β-B was discussed. The Li concentration was analyzed by atomic absorption spectrometry. The changes in the structure and the electronic properties were investigated by X-ray diffraction using the Rietveld method and by electrical conductivity measurements, respectively. Li occupies the A1, D, E and F sites, and the occupancies of the B sites (B13, B16 and B4) decrease with increasing Li doping. In Li- or Mg-doped β-B, electron doping is compensated by the removal of interstitial B atoms at the B16 site and by the generation of vacancies at the B13 and B4 sites. There have been no reports of self-compensation in other crystalline elemental semiconductors.

  7. Development of particle induced gamma-ray emission methods for nondestructive determination of isotopic composition of boron and its total concentration in natural and enriched samples.

    PubMed

    Chhillar, Sumit; Acharya, Raghunath; Sodaye, Suparna; Pujari, Pradeep K

    2014-11-18

    We report simple particle induced gamma-ray emission (PIGE) methods using a 4 MeV proton beam for simultaneous and nondestructive determination of the isotopic composition of boron ((10)B/(11)B atom ratio) and total boron concentrations in various solid samples with natural isotopic composition and enriched with (10)B. It involves measurement of prompt gamma-rays at 429, 718, and 2125 keV from (10)B(p,αγ)(7)Be, (10)B(p, p'γ)(10)B, and (11)B(p, p'γ)(11)B reactions, respectively. The isotopic composition of boron in natural and enriched samples was determined by comparing peak area ratios corresponding to (10)B and (11)B of samples to natural boric acid standard. An in situ current normalized PIGE method, using F or Al, was standardized for total B concentration determination. The methods were validated by analyzing stoichiometric boron compounds and applied to samples such as boron carbide, boric acid, carborane, and borosilicate glass. Isotopic compositions of boron in the range of 0.247-2.0 corresponding to (10)B in the range of 19.8-67.0 atom % and total B concentrations in the range of 5-78 wt % were determined. It has been demonstrated that PIGE offers a simple and alternate method for total boron as well as isotopic composition determination in boron based solid samples, including neutron absorbers that are important in nuclear technology. PMID:25312472

  8. Origin of high ammonium, arsenic and boron concentrations in the proximity of a mine: Natural vs. anthropogenic processes.

    PubMed

    Scheiber, Laura; Ayora, Carlos; Vázquez-Suñé, Enric; Cendón, Dioni I; Soler, Albert; Baquero, Juan Carlos

    2016-01-15

    High ammonium (NH4), arsenic (As) and boron (B) concentrations are found in aquifers worldwide and are often related to human activities. However, natural processes can also lead to groundwater quality problems. High NH4, As and B concentrations have been identified in the confined, deep portion of the Niebla-Posadas aquifer, which is near the Cobre Las Cruces (CLC) mining complex. The mine has implemented a Drainage and Reinjection System comprising two rings of wells around the open pit mine, were the internal ring drains and the external ring is used for water reinjection into the aquifer. Differentiating geogenic and anthropogenic sources and processes is therefore crucial to ensuring good management of groundwater in this sensitive area where groundwater is extensively used for agriculture, industry, mining and human supply. No NH4, As and B are found in the recharge area, but their concentrations increase with depth, salinity and residence time of water in the aquifer. The increased salinity down-flow is interpreted as the result of natural mixing between infiltrated meteoric water and the remains of connate waters (up to 8%) trapped within the pores. Ammonium and boron are interpreted as the result of marine solid organic matter degradation by the sulfate dissolved in the recharge water. The light δ(15)NNH4 values confirm that its origin is linked to marine organic matter. High arsenic concentrations in groundwater are interpreted as being derived from reductive dissolution of As-bearing goethite by dissolved organic matter. The lack of correlation between dissolved Fe and As is explained by the massive precipitation of siderite, which is abundantly found in the mineralization. Therefore, the presence of high arsenic, ammonium and boron concentrations is attributed to natural processes. Ammonium, arsenic, boron and salinity define three zones of groundwater quality: the first zone is close to the recharge area and contains water of sufficient quality for human drinking; the second zone is downflow and contains groundwater suitable for continuous irrigation but not drinkable due to high ammonium concentrations; and the third zone contains groundwater of elevated salinity (up to 5940 μS cm(-1)) and is not useable due to high ammonium, arsenic and boron concentrations. PMID:26437343

  9. Validation of the scanning γ-ray telescope for in vivo dosimetry and boron measurements during BNCT

    NASA Astrophysics Data System (ADS)

    Verbakel, W. F. A. R.

    2001-12-01

    γ-ray telescope scans of a box phantom with inhomogeneous boron concentrations have proven the feasibility of in vivo measurements of different boron distributions in the head of a patient during boron neutron capture therapy (BNCT). Small structures with enhanced boron concentration can be reconstructed in a head phantom, even if the brain compartment of the phantom is surrounded by a skin layer with a ten times higher boron concentration. The motor-controlled telescope can scan the head/phantom, detecting boron and hydrogen prompt γ-rays emitted at neutron capture reactions with a two-dimensional spatial resolution of 14 mm full width at half maximum. For reconstruction of the boron concentrations from the measured γ-ray detection rates, a mathematical reconstruction algorithm is derived and discussed. Proper reconstruction requires position-dependent γ-ray measurements combined with treatment planning programme calculations of the thermal neutron distribution. In a head phantom, in which the brain and the skull (bulk) were represented using a homogeneous boron distribution of 5.2 +/- 0.5 ppm 10B, surrounded by a skin layer with a ten times higher boron concentration, the bulk concentration was reconstructed to 4.7 +/- 0.3 ppm 10B. Telescope scans along and perpendicular to the beam axis showed the influence of inhomogeneities with a high boron concentration such as skin and a simulated blood vessel, respectively with a low boron concentration such as white matter. The profiles of the boron and hydrogen γ-ray detection rates indicate how future patient measurements can be interpreted. In clinical trials, the telescope can then be used to investigate the averaged boron concentration in the bulk of a patient and local enhanced boron concentrations (e.g. in tumour tissue) in order to relate the measured boron dose distributions to the clinical effects of BNCT. Simultaneously, it can serve as quality control of the dosimetry during the irradiation.

  10. Arsenic, Boron, and Fluoride Concentrations in Ground Water in and Near Diabase Intrusions, Newark Basin, Southeastern Pennsylvania

    USGS Publications Warehouse

    Senior, Lisa A.; Sloto, Ronald A.

    2006-01-01

    During an investigation in 2000 by the U.S. Environmental Protection Agency (USEPA) of possible contaminant releases from an industrial facility on Congo Road near Gilbertsville in Berks and Montgomery Counties, southeastern Pennsylvania, concentrations of arsenic and fluoride above USEPA drinking-water standards of 10 ?g/L and 4 mg/L, respectively, and of boron above the USEPA health advisory level of 600 ?g/L were measured in ground water in an area along the northwestern edge of the Newark Basin. In 2003, the USEPA requested technical assistance from the U.S. Geological Survey (USGS) to help identify sources of arsenic, boron, and fluoride in the ground water in the Congo Road area, which included possible anthropogenic releases and naturally occurring mineralization in the local bedrock aquifer, and to identify other areas in the Newark Basin of southeastern Pennsylvania with similarly elevated concentrations of these constituents. The USGS reviewed available data and collected additional ground-water samples in the Congo Road area and four similar hydrogeologic settings. The Newark Basin is the largest of the 13 major exposed Mesozoic rift basins that stretch from Nova Scotia to South Carolina. Rocks in the Newark Basin include Triassic through Jurassic-age sedimentary sequences of sandstones and shales that were intruded by diabase. Mineral deposits of hydrothermal origin are associated with alteration zones bordering intrusions of diabase and also occur as strata-bound replacement deposits of copper and zinc in sedimentary rocks. The USGS review of data available in 2003 showed that water from about 10 percent of wells throughout the Newark Basin of southeastern Pennsylvania had concentrations of arsenic greater than the USEPA maximum contaminant level (MCL) of 10 ?g/L; the highest reported arsenic concentration was at about 70 ?g/L. Few data on boron were available, and the highest reported boron concentration in well-water samples was 60 ?g/L in contrast to concentrations over 5,000 ?g/L in the Congo Road area. Although concentrations of fluoride up to 4 mg/L were reported for a few well-water samples collected throughout the Newark Basin, about 90 percent of the samples had concentrations of 0.5 mg/L or less. The USGS sampled 58 wells primarily in 5 areas in the Newark Basin, southeastern Pennsylvania, from February 2004 through April 2005 to identify other possible areas of elevated arsenic, boron, and fluoride and to characterize the geochemical environment associated with elevated concentrations of these constituents. Sampled wells included 12 monitor wells at an industrial facility near Congo Road, 45 private-supply wells in Berks, Montgomery, and Bucks Counties, and 1 private-supply well near Dillsburg, York County, an area where elevated fluoride in ground water had been reported in the adjacent Gettysburg Basin. Wells were sampled in transects from the diabase through the adjacent hornfels and into the unaltered shales of the Brunswick Group. Field measurements were made of pH, temperature, dissolved oxygen concentration, and specific conductance. Samples were analyzed in the laboratory for major ions, nutrients, total organic carbon, dissolved and total concentrations of selected trace elements, and boron isotopic composition. Generally, the ground water from the 46 private-supply wells had relatively neutral to alkaline pH (ranging from 6.1 to 9.1) and moderate concentrations of dissolved oxygen. Most water samples were of the calcium-bicarbonate type. Concentrations of arsenic up to 60 ?g/L, boron up to 3,950 ?g/L, and fluoride up to 0.70 mg/L were measured. Drinking-water standards or health advisories (for constituents that do not have standards established) were exceeded most frequently (about 20 percent of samples) for arsenic and boron and less frequently (6 percent or less of samples) for total iron, manganese, sulfate, nitrate, lead, molybdenum, and strontium. In water from 12 monitor

  11. A heterogeneous boron distribution in soil influences the poplar root system architecture development

    NASA Astrophysics Data System (ADS)

    Rees, R.; Robinson, B. H.; Hartmann, S.; Lehmann, E.; Schulin, R.

    2009-04-01

    Poplars are well suited for the phytomanagement of boron (B)-contaminated sites, due to their high transpiration rate and tolerance to elevated soil B concentrations. However, the uptake and the fate of B in poplar stands are not well understood. This information is crucial to improve the design of phytomanagement systems, where the primary role of poplars is to reduce B leaching by reducing the water flux through the contaminated material. Like other trace elements, B occurs heterogeneously in soils. Concentrations can differ up to an order of magnitude within centimetres. These gradients affect plant root growth and thus via preferential flow along the roots water and mass transport in soils to ground and surface waters. Generally there are three possible reactions of plant roots to patches with elevated trace element concentrations in soils: indifference, avoidance, or foraging. While avoidance or indifference might seem to be the most obvious strategies, foraging cannot be excluded a priori, because of the high demand of poplars for B compared to other tree species. We aimed to determine the rooting strategies of poplars in soils where B is either homo- or heterogeneously distributed. We planted 5 cm cuttings of Populus tremula var. Birmensdorf clones in aluminum (Al) containers with internal dimensions of 64 x 67 x 1.2 cm. The soil used was subsoil from northern Switzerland with a naturally low B and organic C concentration. We setup two treatments and a control with three replicates each. We spiked a bigger and a smaller portion of the soil with the same amount of B(OH)3-salt, in order to obtain soil concentrations of 7.5 mg B kg-1 and 20 mg B kg-1. We filled the containers with (a) un-spiked soil, (b) the 7.5 mg B kg-1 soil and (c) heterogeneously. The heterogeneous treatment consisted of one third 20 mg B kg-1 soil and two thirds control soil. We grew the poplars in a small greenhouse over 2 months and from then on in a climate chamber for another 3 months. We irrigated the poplars with modified Hoagland's solution that contained no B. We imaged the roots in the soil every 3rd week using neutron radiography (NR) at the Paul-Scherrer Institute. Living roots can be visualised in soil by NR because of their higher water content compared to the surrounding soil. At the end of the growing period, the Al containers were opened and the soil surface was scanned by a standard office scanner. The soil in the containers was divided into nine equal portions representing different depths and spiked or un-spiked regions in soil profile. We separated roots and soil as well as the aerial parts (stems and leaves). We obtained data on root morphological parameters like root length and root density by evaluating scans of the washed root samples with an image evaluation software. All soil and plant samples were dried, weighed and analyzed for B and mineral nutrients using ICP-OES. Plant vitality parameters like water use, growth and number of living leaves did not show any reaction to the treatments. The oldest poplar leaves from poplars in the B-spiked treatments showed signs of light to serious necrosis. From the neutron radiographs it was apparent that poplar roots reached the walls of the Al- containers during the experiment. Primary roots grew at first strongly in lengths in horizontal as well as in vertical direction and only after this lateral root growth was visible. Although the filling and packing of the containers was done with great care to establish an ideally homogeneous soil profile settlement occurred in some containers resulting in gaps in the profile. However, roots growth did not seem to be deranged since roots simply crossed these gaps and continued growth in the adjacent soil patch. The complete results will be available at the time of the conference.

  12. Salinity's influence on boron toxicity in broccoli: I. Impacts on yield, biomass distribution, and water use

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Research addressing the interactive effects of the dual plant stress factors, excess boron and salinity, on crop productivity has expanded considerably over the past few years. The purpose of this research was to determine and quantify the interactive effects of salinity, saltcomposition and boron ...

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

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.

    2007-09-01

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

  14. Tourmaline in the 3.7-3.8 Ga Isua Supracrustal Belt, West Greenland - A window to Boron Concentrations in the Eoarchean Eon

    NASA Astrophysics Data System (ADS)

    Grew, E. S.; Dymek, R. F.; De Hoog, J. C.; Harley, S. L.; Hazen, R. M.; Yates, M. G.

    2013-12-01

    The distribution and mineralogical context of trace elements in Earth's oldest rocks provide insights on Earth's accretion, differentiation, and primordial evolution. One example is boron, which is highly concentrated in Earth's crust and oceans relative to primitive mantle, and, thus the amount of boron on Earth's surface should increase with increasing volume of crust. The earliest B mineral reported in the geological record is metamorphic tourmaline in the Isua Supracrustal Belt, where its abundance belies the notion of there being less boron in the Eoarchean than in more recent time. Chaussidon & Appel (1997, Chem. Geol., 136, 171-180) reported δ11B = --17.3 to --25.0‰ in tourmaline in Isua metachert ("conglomerate"), and δ11B = --12.6 to +5.8 ‰ on tourmaline in Isua metamorphosed mafic volcaniclastics. The large range in the latter rocks was attributed to fractionation during hydrothermal reworking, whereas the more negative values in the metacherts suggested metamorphic tourmaline formed from breakdown of clays with an average δ11B calculated to be about -8 × 7‰ deposited in an ocean having δ11B = +27×11‰, compared to +40 ‰ today, consistent with δ11B = +28‰ calculated from the Chaussidon & Albarède (1992, EPSL, 108, 229-241) model relating increase in sea-water δ11B to proportion of B extracted from Earth's mantle into the oceans and crust. This estimate of Eoarchean seawater δ11B is consistent with fractionation associated with illitization of smectite formed in a marine environment (estimated to be about --35‰) and with crystallization of metamorphic tourmaline from intergranular fluid having the same δ11B as the host metachert (another --2‰ at 500 °C based on tourmaline-water fractionation from Meyer et al. 2008, Contrib. Mineral. Petrol., 156, 259-267). However, this scenario does not adequately explain three rock types in the Isua supracrustals: (1) a tourmaline-quartz lens with ~50% modal tourmaline; (2) a dolomite-tourmaline lens with ~20% modal tourmaline containing accessory chromite, chalcopyrite and gersdorffite, (Ni,Co,Fe)AsS; (3) 'green-mica' schist containing Cr- and Ba-bearing muscovite and accessory tourmaline, sphalerite, chalcopyrite, galena, pentlandite, arsenopyrite and gersdorffite. These sulfides suggest that hydrothermal fluid associated with volcanism introduced B, As and Pb into sedimentary rocks together with Cr, Co and Ni remobilized from associated ultramafic rocks. Crystallization of tourmaline in (1) with δ11B =--22‰ (Swihart & Moore, 1989, Geochim. Cosmochim. Acta, 53, 911-916) implies δ11B of --17 ‰ to--19 ‰ in the hydrothermal fluid from which it crystallized (assuming tourmaline-water fractionation at 200-350 °C based on Meyer et al. 2008). These fluid δ11B suggest a continental source of the boron, since δ11B of continental detritus averages -10 × 5‰, i.e., more negative (lighter) than oceanic crust (Leeman & Sisson, 1996, Rev. Mineral., 33, 645-707). As the tourmaline-bearing rocks are part of the younger (ca. 3700 Ma) of two terranes in the Isua supracrustal belt (Nutman & Friend, 2009, Precamb. Res., 172, 189-211), we suggest that boron isotopic composition and abundance resulted from recycling of boron in supracrustal rocks of the older (ca. 3800 Ma) terrane and its remobilization in a volcanic system prior to precipitation as tourmaline in rocks of the younger terrane.

  15. Possible roles of pH, temperature, and partial dissolution in determining boron concentration and isotopic composition in planktonic foraminifera

    USGS Publications Warehouse

    Wara, M.W.; Delaney, M.L.; Bullen, T.D.; Ravelo, A.C.

    2003-01-01

    We present the first continuous records from 0 to 5 Ma (in 0.333 m.y. integrated time steps) of paired boron/calcium (B/Ca) ratios and boron isotopes (??11B) in the planktonic foraminifera Globogerinoides sacculifer (without sacc) from a site in the western equatorial Pacific Ocean (Ocean Drilling Program Site 806). These measurements, the first made in conjunction with calcification temperature (magnesium/calcium ratios) and average shell mass measurements, indicate that pH is not the sole environmental variable controlling B in planktonic foraminiferal calcite. Our data are consistent with calcification temperature exerting a primary control on B concentration and isotopic composition in planktonic foraminifera. If so, calcification temperature must be taken into account if pH for past oceans and atmospheric pCO2 are to be estimated from B isotope measurements in foraminiferal calcite. Doing so will substantially increase the uncertainty of PH estimates. Although this work was designed as a temporal study, its results define new aspects of calibrating the ??11B paleo-pH tracer. Copyright 2003 by the American Geophysical Union.

  16. Dietary boron decreases peak pancreatic in situ insulin release in chicks and plasma insulin concentrations in rats regardless of vitamin D or magnesium status.

    PubMed

    Bakken, Naomi A; Hunt, Curtiss D

    2003-11-01

    Because dietary boron deprivation induces hyperinsulinemia in vitamin D-deprived rats, the influence of dietary boron on insulin metabolism as modified by nutritional stressors was examined in two animal models. Male weanling Sprague-Dawley rats were assigned to each of four (Experiment 1) or 8 (Experiment 2) dietary groups for 35 d: the basal diet (< 0.2 mg B; <1.0 mg Mg/kg) was supplemented with boron (as orthoboric acid) to contain <0.2 or 2.0 (a physiologic amount) mg B/kg; with magnesium (as magnesium acetate), at 100 (inadequate) or 360-400 (adequate) mg/kg; and with cholecalciferol [vitamin D-3; 25 microg/kg for study length (Experiment 2), or, depleted for 16-17 d then repleted until end of experiment (Experiments 1 and 2)]. In the rat model, boron reduced plasma insulin (Experiment 1, P < 0.002; Experiment 2, P < 0.03), but did not change glucose concentrations regardless of vitamin D-3 or magnesium status. Cockerels (1 d old) were fed a ground corn, high protein casein and corn oil-based basal diet (low boron; 0.3 mg B/kg) supplemented with boron as orthoboric acid to contain 0.3 or 1.65 mg/kg (a physiologic amount) and vitamin D-3 at 3.13 (inadequate) or 15.60 (adequate) microg/kg. In the chick model, boron decreased (P < 0.045) in situ peak pancreatic insulin release at 26-37 d of age regardless of vitamin D-3 nutriture. These results suggest that physiologic amounts of boron may help reduce the amount of insulin required to maintain plasma glucose. PMID:14608076

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

    TOXLINE Toxicology Bibliographic Information

    Wittig A; Michel J; Moss RL; Stecher-Rasmussen F; Arlinghaus HF; Bendel P; Mauri PL; Altieri S; Hilger R; Salvadori PA; Menichetti L; Zamenhof R; Sauerwein WA

    2008-10-01

    Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy. BNCT strongly depends on the selective uptake of 10B in tumor cells and on its distribution inside the cells. The chemical properties of boron and the need to discriminate different isotopes make the investigation of the concentration and distribution of 10B a challenging task. The most advanced techniques to measure and image boron are described, both invasive and non-invasive. The most promising approach for further investigation will be the complementary use of the different techniques to obtain the information that is mandatory for the future of this innovative treatment modality.

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

    PubMed

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

    2008-10-01

    Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy. BNCT strongly depends on the selective uptake of 10B in tumor cells and on its distribution inside the cells. The chemical properties of boron and the need to discriminate different isotopes make the investigation of the concentration and distribution of 10B a challenging task. The most advanced techniques to measure and image boron are described, both invasive and non-invasive. The most promising approach for further investigation will be the complementary use of the different techniques to obtain the information that is mandatory for the future of this innovative treatment modality. PMID:18439836

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

    SciTech Connect

    Suzuki, Minoru . E-mail: msuzuki@rri.kyoto-u.ac.jp; Sakurai, Yoshinori; Masunaga, Shinichiro; Kinashi, Yuko; Nagata, Kenji; Maruhashi, Akira; Ono, Koji

    2006-12-01

    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.

  20. Macroscopic geometric heterogeneity effects in radiation dose distribution analysis for boron neutron capture therapy

    SciTech Connect

    Moran, J.M.; Nigg, D.W.; Wheeler, F.J.; Bauer, W.F. )

    1992-05-01

    Calculations of radiation flux and dose distributions for boron neutron capture therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This paper describes such a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for the tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for this model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous-tissue model. Comparison of the results showed that peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10%--20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

  1. A benchmark analysis of radiation flux distribution for Boron Neutron Capture Therapy of canine brain tumors

    SciTech Connect

    Moran, J.M.

    1992-02-01

    Calculations of radiation flux and dose distributions for Boron Neutron Capture Therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly-heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This work describes a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador Retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador Retriever head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for the model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous tissue model. Comparison of the results showed that the peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.

  2. Direct assessment of the mechanical modulus of graphene co-doped with low concentrations of boron-nitrogen by a non-contact approach

    NASA Astrophysics Data System (ADS)

    Pan, Shun-Hsien; Medina, Henry; Wang, Sheng-Bo; Chou, Li-Jen; Wang, Zhiming M.; Chen, Kuei-Hsien; Chen, Li-Chyong; Chueh, Yu-Lun

    2014-07-01

    Boron and nitrogen co-doping has been shown to be an effective way to induce a band gap in graphene for electrical applications but only a few theoretical studies have been done to understand the elastic and mechanical properties of the modified graphene. Until now, no experimental assessment of the mechanical modulus of boron-nitrogen-doped graphene (BNG) has been reported in the literature. Here, we demonstrate a novel non-contact approach to determine the in-plane stiffness of BNG at low BN concentrations. The in-plane stiffness of BNG with 2 at% BN concentration was estimated to be about 309 N m-1, which is lower than that of pristine graphene, in good agreement with some theoretical studies. Moreover, we correlated the conductivity of BNG with induced strain and found the BNG to be more sensitive than pristine graphene in response to externally applied strain. This result indicates that BNG is a more suitable material than graphene for strain sensor applications.Boron and nitrogen co-doping has been shown to be an effective way to induce a band gap in graphene for electrical applications but only a few theoretical studies have been done to understand the elastic and mechanical properties of the modified graphene. Until now, no experimental assessment of the mechanical modulus of boron-nitrogen-doped graphene (BNG) has been reported in the literature. Here, we demonstrate a novel non-contact approach to determine the in-plane stiffness of BNG at low BN concentrations. The in-plane stiffness of BNG with 2 at% BN concentration was estimated to be about 309 N m-1, which is lower than that of pristine graphene, in good agreement with some theoretical studies. Moreover, we correlated the conductivity of BNG with induced strain and found the BNG to be more sensitive than pristine graphene in response to externally applied strain. This result indicates that BNG is a more suitable material than graphene for strain sensor applications. Electronic supplementary information (ESI) available: Actual strain applied on pristine graphene and 2BNG; Raman spectra of CVD graphene and 2BNG transferred onto PDMS substrates; schematic of the atomic model; I2D/IG Raman ratio as a function of the PDMS strain for pristine graphene in the reversible deformation region; Raman information of the I2D/IG ratio for pristine graphene in the irreversible deformation region; Raman G band for graphene before and under applied strain; I2D/IG Raman ratio as a function of the PDMS strain for the 2BNG film in the reversible deformation region; Raman information of the I2D/IG ratio for 2BNG in the irreversible deformation region; Raman G band for 2BNG before and under applied strain; the schematic diagram of the deposition process for a strain sensor device; schematic diagram of the 2D stress applied to graphene and BNG films; actual strain on graphene and BNG measured by Raman versus PDMS strain; schematic diagrams of the strain distribution. See DOI: 10.1039/c4nr00495g

  3. Biokinetic analysis of tissue boron (¹⁰B) concentrations of glioma patients treated with BNCT in Finland.

    PubMed

    Koivunoro, H; Hippeläinen, E; Auterinen, I; Kankaanranta, L; Kulvik, M; Laakso, J; Seppälä, T; Savolainen, S; Joensuu, H

    2015-12-01

    A total of 98 patients with glioma were treated with BPA-F-mediated boron neutron capture therapy (BNCT) in Finland from 1999 to 2011. Thirty-nine (40%) had undergone surgery for newly diagnosed glioblastoma and 59 (60%) had malignant glioma recurrence after surgery. In this study we applied a closed 3-compartment model based on dynamic (18)F-BPA-PET studies to estimate the BPA-F concentrations in the tumor and the normal brain with time. Altogether 22 patients with recurrent glioma, treated within the context of a clinical trial, were evaluated using their individual measured whole blood (10)B concentrations as an input to the model. The delivered radiation doses to tumor and the normal brain were recalculated based on the modeled (10)B concentrations in the tissues during neutron irradiation. The model predicts from -7% to +29% (average, +11%) change in the average tumor doses as compared with the previously estimated doses, and from 17% to 61% (average, 36%) higher average normal brain doses than previously estimated due to the non-constant tumor-to-blood concentration ratios and considerably higher estimated (10)B concentrations in the brain at the time of neutron irradiation. PMID:26363564

  4. PGNAA system preliminary design and measurement of In-Hospital Neutron Irradiator for boron concentration measurement.

    PubMed

    Zhang, Zizhu; Chong, Yizheng; Chen, Xinru; Jin, Congjun; Yang, Lijun; Liu, Tong

    2015-12-01

    A prompt gamma neutron activation analysis (PGNAA) system has been recently developed at the 30-kW research reactor In-Hospital Neutron Irradiator (IHNI) in Beijing. Neutrons from the specially designed thermal neutron beam were used. The thermal flux of this beam is 3.08×10(6) cm(-2) s(-1) at a full reactor power of 30 kW. The PGNAA system consists of an n-type high-purity germanium (HPGe) detector of 40% efficiency, a digital spectrometer, and a shielding part. For both the detector shielding part and the neutron beam shielding part, the inner layer is composed of (6)Li2CO3 powder and the outer layer lead. The boron-10 sensitivity of the PGNAA system is approximately 2.5 cps/ppm. Two calibration curves were produced for the 1-10 ppm and 10-50 ppm samples. The measurement results of the control samples were in accordance with the inductively coupled plasma atomic emission spectroscopy (ICP-AES) results. PMID:26242556

  5. Electrochemical oxidation of tramadol in low-salinity reverse osmosis concentrates using boron-doped diamond anodes.

    PubMed

    Lütke Eversloh, Christian; Schulz, Manoj; Wagner, Manfred; Ternes, Thomas A

    2015-04-01

    The electrochemical treatment of low-salinity reverse osmosis (RO) concentrates was investigated using tramadol (100 μM) as a model substance for persistent organic contaminants. Galvanostatic degradation experiments using boron-doped diamond electrodes at different applied currents were conducted in RO concentrates as well as in ultra-pure water containing either sodium chloride or sodium sulfate. Kinetic investigations revealed a significant influence of in-situ generated active chlorine besides direct anodic oxidation. Therefore, tramadol concentrations decreased more rapidly at elevated chloride content. Nevertheless, reduction of total organic carbon (TOC) was found to be comparatively low, demonstrating that transformation rather than mineralization was taking place. Early stage product formation could be attributed to both direct and indirect processes, including demethylation, hydroxylation, dehydration, oxidative aromatic ring cleavage and halogenation reactions. The latter led to various halogenated derivatives and resulted in AOX (adsorbable organic halogens) formation in the lower mg/L-range depending on the treatment conditions. Characterisation of transformation products (TPs) was achieved via MS(n) experiments and additional NMR measurements. Based on identification and quantification of the main TPs in different matrices and on additional potentiostatic electrolysis, a transformation pathway was proposed. PMID:25660808

  6. Fabrication of boron articles

    DOEpatents

    Benton, Samuel T.

    1976-01-01

    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.

  7. Effects of sulfur, zinc, iron, copper, manganese, and boron applications on sunflower yield and plant nutrient concentration

    SciTech Connect

    Hilton, B.R.; Zubriski, J.C.

    1985-01-01

    Sulfur, zinc, iron, copper, manganese, and boron application did not affect the seed yield or oil percentage of sunflower (Helianthus annuus L.) on both dryland and irrigated soils in North Dakota in 1981. Field averages indicated significant Zn, Mn, and B uptake by sunflower at the 12-leaf stage as a result of fertilization with these elements. Increased Zn uptake was also observed in the uppermost mature leaf at anthesis from zinc fertilization. Although sunflower yield from boron fertilization was not significantly different from the check, a trend was observed in which boron fertilization seemed to decrease sunflower yield. Sunflower yields from the boron treatment were the lowest out of seven treatments in three out of four fields. Also, sunflower yield from the boron treatment was significantly lower than both iron and sulfur treatments when all fields were combined.

  8. Exact analytic flux distributions for two-dimensional solar concentrators.

    PubMed

    Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M

    2013-07-01

    A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers. PMID:23842256

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

    PubMed

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

    2012-11-15

    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 μM (tTHMs), and 12 and 22 μM (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

  10. Co-variation of Boron Concentrations and Isotope Ratios in Glasses From the Laki- Grimsvotn Fissure Eruption of 1783-1784

    NASA Astrophysics Data System (ADS)

    Brounce, M.; Feineman, M. D.; Gurenko, A.; Lafemina, P.

    2008-12-01

    The Laki-Grimsvotn fissure, located in the Eastern Volcanic Zone in southeast Iceland, erupted in 1783-1784 producing over 15 km3 of basaltic lava and associated aerosols. We have collected proximal tephra samples from the fissure, north and south of Laki (hyaloclastite mountain). Trace element concentrations and boron isotope analyses were performed on matrix glasses and plagioclase-hosted melt inclusions from various eruptive phases from this eruption using SIMS (Cameca IMS 3F and 1280) at the Woods Hole Oceanographic Institution. Preliminary data from SIMS boron isotope analyses shows variation in δ11B from -5 to -19‰ (2σ<±4‰ at B concentration level <1.5 ppm). A negative correlation between δ11B and boron concentrations in the melt inclusions demonstrates that as boron concentrations increase in the residual melt, the melt is also increasingly more enriched in 10B relative to 11B. Scoria lapilli glasses form a relatively tight cluster, defining the lowest δ11B values (-10 to -19‰) and highest boron concentrations (1.1-1.4 ppm). Typical δ11B values for MORBs are around -5‰ and may represent the primitive end member of observed results from the Laki melt inclusions. Hervig et al. (2002) have shown experimentally that 11B is partitioned into the fluid phase and 10B into a silicate melt when the two are held at equilibrium, which could account for some of the variation observed here (Hervig et al. observed 3‰ fractionation between the fluid and basaltic melt). They have also shown that B is compatible in basaltic melt during degassing. Thus simultaneous degassing and fractional crystallization could explain the increase in B during degassing, even as δ11B decreases. Based on our current understanding, however, it seems unlikely that degassing alone can account for the >10‰fractionation observed in the Laki melt inclusions. Isotopically light boron may also be introduced into the system by shallow-level assimilation of preexisting altered hyaloclastite material prior to eruption, as has been suggested by Bindeman et al. (2008) on the basis of oxygen isotope data. R. Hervig et al. (2002), Am. Min. 87, 769-774 I. Bindeman et al. (2008), Geochim. Cosmochim. Acta, 72, 4397-4420

  11. Monitoring the distribution of prompt gamma rays in boron neutron capture therapy using a multiple-scattering Compton camera: A Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Lee, Taewoong; Lee, Hyounggun; Lee, Wonho

    2015-10-01

    This study evaluated the use of Compton imaging technology to monitor prompt gamma rays emitted by 10B in boron neutron capture therapy (BNCT) applied to a computerized human phantom. The Monte Carlo method, including particle-tracking techniques, was used for simulation. The distribution of prompt gamma rays emitted by the phantom during irradiation with neutron beams is closely associated with the distribution of the boron in the phantom. Maximum likelihood expectation maximization (MLEM) method was applied to the information obtained from the detected prompt gamma rays to reconstruct the distribution of the tumor including the boron uptake regions (BURs). The reconstructed Compton images of the prompt gamma rays were combined with the cross-sectional images of the human phantom. Quantitative analysis of the intensity curves showed that all combined images matched the predetermined conditions of the simulation. The tumors including the BURs were distinguishable if they were more than 2 cm apart.

  12. Distribution analysis of airborne nicotine concentrations in hospitality facilities.

    PubMed

    Schorp, Matthias K; Leyden, Donald E

    2002-02-01

    A number of publications report statistical summaries for environmental tobacco smoke (ETS) concentrations. Despite compelling evidence for the data not being normally distributed, these publications typically report the arithmetic mean and standard deviation of the data, thereby losing important information related to the distribution of values contained in the original data. We were interested in the frequency distributions of reported nicotine concentrations in hospitality environments and subjected available data to distribution analyses. The distribution of experimental indoor airborne nicotine concentration data taken from hospitality facilities worldwide was fit to lognormal, Weibull, exponential, Pearson (Type V), logistic, and loglogistic distribution models. Comparison of goodness of fit (GOF) parameters and indications from the literature verified the selection of a lognormal distribution as the overall best model. When individual data were not reported in the literature, statistical summaries of results were used to model sets of lognormally distributed data that are intended to mimic the original data distribution. Grouping the data into various categories led to 31 frequency distributions that were further interpreted. The median values in nonsmoking environments are about half of the median values in smoking sections. When different continents are compared, Asian, European, and North American median values in restaurants are about a factor of three below levels encountered in other hospitality facilities. On a comparison of nicotine concentrations in North American smoking sections and nonsmoking sections, median values are about one-third of the European levels. The results obtained may be used to address issues related to exposure to ETS in the hospitality sector. PMID:11868665

  13. Advanced microstructure of boron carbide.

    PubMed

    Werheit, Helmut; Shalamberidze, Sulkhan

    2012-09-26

    The rhombohedral elementary cell of the complex boron carbide structure is composed of B(12) or B(11)C icosahedra and CBC, CBB or B□B (□, vacancy) linear arrangements, whose shares vary depending on the actual chemical compound. The evaluation of the IR phonon spectra of isotopically pure boron carbide yields the quantitative concentrations of these components within the homogeneity range. The structure formula of B(4.3)C at the carbon-rich limit of the homogeneity range is (B(11)C) (CBC)(0.91) (B□B)(0.09) (□, vacancy); and the actual structure formula of B(13)C(2) is (B(12))(0.5)(B(11)C)(0.5)(CBC)(0.65)(CBB)(0.16) (B□B)(0.19), and deviates fundamentally from (B(12))CBC, predicted by theory to be the energetically most favourable structure of boron carbide. In reality, it is the most distorted structure in the homogeneity range. The spectra of (nat)B(x)C make it evident that boron isotopes are not randomly distributed in the structure. However, doping with 2% silicon brings about a random distribution. PMID:22945740

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

    SciTech Connect

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

    1981-01-01

    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.

  15. Boronated liposome development and evaluation

    SciTech Connect

    Hawthorne, M.F.

    1995-11-01

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

  16. Turbulent Concentration of Chondrules: Size Distribution and Multifractal Scaling

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.; Hogan, Robert C.; Paque, Julie M.; Dobrovolskis, Anthony R.

    1999-01-01

    Size-selective concentration of particles in 3D turbulence may be related to collection of chondrules and other constituents into primitive bodies in a weakly turbulent protoplanetary nebula. In the terrestrial planet region, both the characteristic size and narrow size distribution of chondrules are explained, whereas "fluffier" particles would be concentrated in lower density, or more intensely turbulent, regions of the nebula. The spatial distribution of concentrated particle density obeys multifractal scaling, suggesting a dose tie to the turbulent cascade process. This scaling behavior allows predictions of the concentration probabilities to be made in the protoplanetary nebula, which are so large (> 10(exp 3) - 10(exp 4)) that further studies must be made of the role of mass loading.

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

    NASA Astrophysics Data System (ADS)

    Zasneda, Sabriani; Widita, Rena

    2010-06-01

    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, α) 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 10B/g blood.

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

    SciTech Connect

    Zasneda, Sabriani; Widita, Rena

    2010-06-22

    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.

  19. Impact of carbon co-implantation on boron distribution and activation in silicon studied by atom probe tomography and spreading resistance measurements

    NASA Astrophysics Data System (ADS)

    Shimizu, Yasuo; Takamizawa, Hisashi; Inoue, Koji; Yano, Fumiko; Kudo, Shuichi; Nishida, Akio; Toyama, Takeshi; Nagai, Yasuyoshi

    2016-02-01

    The impact of carbon (C) co-implantation on boron (B) activation in crystalline silicon was investigated. The detailed distribution of B and C atoms and B activation ratios dependent on the C ion-implantation energies were examined based on three-dimensional spatial mappings of B and C obtained by atom probe tomography and from depth profiles of their concentrations from secondary ion mass spectrometry and depth profiles of carrier concentrations with spreading resistance measurements. At all C implantation energies (8, 15, and 30 keV), B out-diffusion during activation annealing was reduced, so that more B atoms were observed in the C co-implanted samples. The carrier concentration was decreased throughout the entire implanted region for C implantation energies of 15 and 30 keV, although it was only increased at greater depths for C co-implantation at 8 keV. Two different effects of C co-implantation, (I) reduction of B out-diffusion and (II) influence of B activation, were confirmed.

  20. On spatial pattern of concentration distribution for Taylor dispersion process

    PubMed Central

    Wu, Zi; Fu, Xudong; Wang, Guangqian

    2016-01-01

    Taylor dispersion is a key concept in many fields. In the present paper, we characterize the pattern of the complete spatial concentration distribution for laminar tube flow; the obtained simple description is shown to represent the nature of Taylor dispersion. Importantly, we find that during the approach to the longitudinal normality of the transverse mean concentration at the time scale of R2/D (R is the tube radius and D is the molecular diffusivity), the solute concentration becomes uniformly distributed across a family of invariant curved transverse surfaces instead of the flat cross-sections in the traditional view. The family of curved surfaces is analytically determined, and a transformation is devised for the previously obtained analytical solution to discuss the decay of the concentration difference across the curved surfaces. The approach to a uniform concentration across the flat cross-sections to the same degree (~3% by concentration difference percentage), achieved at a time-scale of 100 R2/D, is shown to be the natural consequence of the longitudinal separation of the concentration contours on the curved surfaces. PMID:26867803

  1. On spatial pattern of concentration distribution for Taylor dispersion process

    NASA Astrophysics Data System (ADS)

    Wu, Zi; Fu, Xudong; Wang, Guangqian

    2016-02-01

    Taylor dispersion is a key concept in many fields. In the present paper, we characterize the pattern of the complete spatial concentration distribution for laminar tube flow; the obtained simple description is shown to represent the nature of Taylor dispersion. Importantly, we find that during the approach to the longitudinal normality of the transverse mean concentration at the time scale of R2/D (R is the tube radius and D is the molecular diffusivity), the solute concentration becomes uniformly distributed across a family of invariant curved transverse surfaces instead of the flat cross-sections in the traditional view. The family of curved surfaces is analytically determined, and a transformation is devised for the previously obtained analytical solution to discuss the decay of the concentration difference across the curved surfaces. The approach to a uniform concentration across the flat cross-sections to the same degree (~3% by concentration difference percentage), achieved at a time-scale of 100 R2/D, is shown to be the natural consequence of the longitudinal separation of the concentration contours on the curved surfaces.

  2. On spatial pattern of concentration distribution for Taylor dispersion process.

    PubMed

    Wu, Zi; Fu, Xudong; Wang, Guangqian

    2016-01-01

    Taylor dispersion is a key concept in many fields. In the present paper, we characterize the pattern of the complete spatial concentration distribution for laminar tube flow; the obtained simple description is shown to represent the nature of Taylor dispersion. Importantly, we find that during the approach to the longitudinal normality of the transverse mean concentration at the time scale of R(2)/D (R is the tube radius and D is the molecular diffusivity), the solute concentration becomes uniformly distributed across a family of invariant curved transverse surfaces instead of the flat cross-sections in the traditional view. The family of curved surfaces is analytically determined, and a transformation is devised for the previously obtained analytical solution to discuss the decay of the concentration difference across the curved surfaces. The approach to a uniform concentration across the flat cross-sections to the same degree (~3% by concentration difference percentage), achieved at a time-scale of 100 R(2)/D, is shown to be the natural consequence of the longitudinal separation of the concentration contours on the curved surfaces. PMID:26867803

  3. 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...

  4. 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)

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

    2009-08-01

    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 τ( t) and α( 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.

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

    PubMed Central

    Woods, W G

    1994-01-01

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

  6. Ab initio study of boron in α-iron: Migration barriers and interaction with point defects

    NASA Astrophysics Data System (ADS)

    Bialon, A. F.; Hammerschmidt, T.; Drautz, R.

    2013-03-01

    Boron is a common alloying element in modern steels with a significant influence on the mechanical properties already at concentrations of only a few parts per million. The effect of boron depends on its distribution in the microstructure. Here, we characterize the elemental factors that determine the boron distribution in α-iron by density functional theory calculations. Boron as point defect has been considered in substitutional and interstitial sites. The calculated migration barriers for the substitutional and interstitial mechanisms show the first nearest-neighbor hops being preferred over second nearest-neighbor hops. A dissociative mechanism shows boron migrating via an interstitial mechanism to be likely trapped by vacancies. In order to characterize the interaction with other point defects, we determined the distance-dependent interaction energy of a boron defect with a vacancy, a second boron, and with hydrogen, carbon, nitrogen, oxygen, aluminum, silicon, phosphorus, and sulfur atoms. We find that substitutional boron binds strongly to interstitial point defects with dumbbell formation and weaker to substitutional point defects. Interstitial boron tends to repel substitutional and interstitial point defects. We find a similarity of substitutional boron and vacancies regarding their influence on elastic properties and their interaction with point defects in α-iron.

  7. Concentration distribution of contaminant transport in wetland flows

    NASA Astrophysics Data System (ADS)

    Wu, Zi; Fu, Xudong; Wang, Guangqian

    2015-06-01

    Study on contaminant transport in wetland flows is of fundamental importance. Recent investigation on scalar transport in laminar tube flows (Wu and Chen, 2014. J. Fluid Mech., 740: 196-213.) indicates that the vertical concentration difference in wetland flows may be remarkable for a very long time, which cannot be captured by the extensively applied one-dimensional Taylor dispersion model. To understand detailed information for the vertical distribution of contaminant in wetland flows, for the first time, the present paper deduces an analytical solution for the multi-dimensional concentration distribution by the method of mean concentration expansion. The solution is verified by both our analytical and numerical results. Representing the effects of vegetation in wetlands, the unique dimensionless parameter α can cause the longitudinal contraction of the contaminant cloud and the change of the shape of the concentration contours. By these complicated effects, it is shown unexpectedly that the maximum vertical concentration difference remains nearly unaffected, although its longitudinal position may change. Thus the slow-decaying transient effect (Wu and Chen, 2014. J. Hydrol., 519: 1974-1984.) is shown also apply to the process of contaminant transport in wetland flows.

  8. Remote sensing of hydrogen gas concentration distribution by Raman lidar

    NASA Astrophysics Data System (ADS)

    Asahi, Ippei; Sugimoto, Sachiyo; Ninomiya, Hideki; Fukuchi, Tetsuo; Shiina, Tatsuo

    2012-11-01

    Hydrogen is expected to become an energy source in the next generation. Although hydrogen gas is a combustible gas with a large explosion concentration range, leakage is presently monitored by contact type gas sensors. The technology for locating a leak and remote sensing of gas concentration distribution is required in case of hydrogen gas leaks. In this study, remote sensing technology of hydrogen gas concentration distribution using a Raman lidar was developed. The lidar system consisted of a pulsed Nd:YAG laser of wavelength 354.7 nm and a Galilean telescope of aperture 170 mm. The system could detect hydrogen gas by vibrational Raman scattering. In this method, hydrogen gas concentration could be measured based on the ratio of the Raman scattering signals from hydrogen gas and from atmospheric nitrogen, which were simultaneously measured. In this manner, the geometrical form factor of the biaxial lidar and the instrumental function were canceled. Hydrogen gas concentration of 0.6-100% could be measured at a distance 13m using this system.

  9. Saharan Dust Particle Size And Concentration Distribution In Central Ghana

    NASA Astrophysics Data System (ADS)

    Sunnu, A. K.

    2010-12-01

    A.K. Sunnu*, G. M. Afeti* and F. Resch+ *Department of Mechanical Engineering, Kwame Nkrumah University of Science and Technology (KNUST) Kumasi, Ghana. E-mail: albertsunnu@yahoo.com +Laboratoire Lepi, ISITV-Université du Sud Toulon-Var, 83162 La Valette cedex, France E-mail: resch@univ-tln.fr Keywords: Atmospheric aerosol; Saharan dust; Particle size distributions; Particle concentrations. Abstract The Saharan dust that is transported and deposited over many countries in the West African atmospheric environment (5°N), every year, during the months of November to March, known locally as the Harmattan season, have been studied over a 13-year period, between 1996 and 2009, using a location at Kumasi in central Ghana (6° 40'N, 1° 34'W) as the reference geographical point. The suspended Saharan dust particles were sampled by an optical particle counter, and the particle size distributions and concentrations were analysed. The counter gives the total dust loads as number of particles per unit volume of air. The optical particle counter used did not discriminate the smoke fractions (due to spontaneous bush fires during the dry season) from the Saharan dust. Within the particle size range measured (0.5 μm-25 μm.), the average inter-annual mean particle diameter, number and mass concentrations during the northern winter months of January and February were determined. The average daily number concentrations ranged from 15 particles/cm3 to 63 particles/cm3 with an average of 31 particles/cm3. The average daily mass concentrations ranged from 122 μg/m3 to 1344 μg/m3 with an average of 532 μg/m3. The measured particle concentrations outside the winter period were consistently less than 10 cm-3. The overall dust mean particle diameter, analyzed from the peak representative Harmattan periods over the 13-year period, ranged from 0.89 μm to 2.43 μm with an average of 1.5 μm ± 0.5. The particle size distributions exhibited the typical distribution pattern for atmospheric aerosols with a coarse mode diameter situated at about 3.5 μm. The experimental results reported in this study will be important in validating satellite based observations and simulation models of the African dust plume towards the Gulf of Guinea during winter.

  10. Boron neutron capture therapy for malignant melanoma: An experimental approach

    SciTech Connect

    Larsson, B.S.; Larsson, B.; Roberto, A. )

    1989-07-01

    Previous studies have shown that some thioamides, e.g., thiouracil, are incorporated as false precursors into melanin during its synthesis. If boronated analogs of the thioamides share this property, the melanin of melanotic melanomas offers a possibility for specific tumoural uptake and retention of boron as a basis for neutron capture therapy. We report on the synthesis of boronated 1H-1,2,4-triazole-3-thiol (B-TZT), boronated 5-carboxy-2-thiouracil (B-CTU), and boronated 5-diethylaminomethyl-2-thiouracil (B-DEAMTU) and the localization of these substances in melanotic melanomas transplanted to mice. The distribution in the mice was studied by boron neutron capture radiography. B-TZT and B-CTU showed the highest tumour:normal tissue concentration ratios, with tumour:liver ratios of about 4 and tumour:muscle ratios of about 14; B-DEAMTU showed corresponding ratios of 1.4 and 5, respectively. The absolute concentration of boron in the tumours, however, was more than three times higher in the mice injected with B-TZT, compared with B-CTU. The results suggest that B-TZT may be the most promising compound of the three tested with regard to possible therapy of melanotic melanomas.

  11. Distribution of indoor radon concentrations in Pennsylvania, 1990-2007

    USGS Publications Warehouse

    Gross, Eliza L.

    2013-01-01

    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.

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

    PubMed

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

    2016-01-01

    Boron-resistant fungi were isolated from the wastewater of a boron mine in Turkey. Boron removal efficiencies of Penicillium crustosum and Rhodotorula mucilaginosa were detected in different media compositions. Minimal Salt Medium (MSM) and two different waste media containing molasses (WM-1) or whey + molasses (WM-2) were tested to make this process cost effective when scaled up. Both isolates achieved high boron removal yields at the highest boron concentrations tested in MSM and WM-1. The maximum boron removal yield by P. crustosum was 45.68% at 33.95 mg l(-1) initial boron concentration in MSM, and was 38.97% at 42.76 mg l(-1) boron for R. mucilaginosa, which seemed to offer an economically feasible method of removing boron from the effluents. PMID:26877036

  13. Spatial distribution of the daily precipitation concentration index in Algeria

    NASA Astrophysics Data System (ADS)

    Benhamrouche, A.; Boucherf, D.; Hamadache, R.; Bendahmane, L.; Martin-Vide, J.; Teixeira Nery, J.

    2015-03-01

    In this paper, the spatial and temporal distribution of the daily precipitation concentration index (CI) in Algeria (south Mediterranean Sea) has been assessed. CI is an index related to the rainfall intensity and erosive capacity; therefore, this index is of great interest for studies on torrential rainfall and floods. Forty-two daily rainfall series based on high-quality and fairly regular rainfall records for the period from 1970 to 2008 were used. The daily precipitation CI results allowed the identification of three climate zones: the northern country, characterized by coastal regions with CI values between 0.59 and 0.63; the highlands, with values between 0.57 and 0.62, except for the region of Biskra (CI = 0.70); and the southern region of the country, with high rainfall concentrations with values between 0.62 and 0.69.

  14. Concentrations and size distributions of Antarctic stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ferry, G. V.; Pueschel, R. F.; Neish, E.; Schultz, M.

    1989-01-01

    Particle Measuring Systems laser particle spectrometer (ASAS-X and FSSP) probes were used to measure aerosol particle concentrations and size distributions during 11 ER-2 flights between Punta Arenas (53 deg S) and Antarctica (up to 72 deg S) from August 17 to September 22, 1987. The time resolution was 10 s, corresponding to a spatial resolution of 2 km. The data were divided into two size classes (0.05-0.25 and 0.53-5.5 micron radius) to separate the small particle from the coarse particle populations. Results show that the small-particle concentrations are typical for a background aerosol during volcanic quiescence. This concentration is generally constant along a flight track; in only one instance a depletion of small particles during a polar stratospheric cloud (PSC) encounter was measured, suggesting a nucleation of type I PSC particles on background aerosols. Temporary increases of the coarse particle concentrations indicated the presence of tenuous polar stratospheric clouds that were encountered most frequently at the southernmost portion of a flight track and when the aircraft descended to lower altitudes. During 'particle events', particle modes were found at 0.6-micron radius, corresponding to type I PSCs, and occasionally, at 2.0-micron radius corresponding to type II PSCs.

  15. Vertical distribution of HOx concentrations driven by boundary layer dynamics

    NASA Astrophysics Data System (ADS)

    Gomm, Sebastian; Broch, Sebastian; Fuchs, Hendrik; Hofzumahaus, Andreas; Holland, Frank; Bohn, Birger; Häseler, Rolf; Jäger, Julia; Kaiser, Jennifer; Keutsch, Frank; Li, Xin; Lu, Keding; Lohse, Insa; Rohrer, Franz; Tillmann, Ralf; Wegener, Robert; Wolfe, Glenn; Mentel, Thomas F.; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    The hydroxyl (OH) and hydroperoxy (HO2) radicals are key compounds for the degradation of pollutants in the atmosphere. Therefore, accurate and precise measurements of HOx radicals (= OH + HO2) at different altitudes and in different regions are necessary to test our understanding of atmospheric chemical processes. The planetary boundary layer (PBL) is of special interest as it is chemically the most active part of the atmosphere. Until today, there is a general lack of measurements investigating the distribution of radicals, trace gases, and aerosols in the PBL with high spatial resolution. Here, we present results of measurements performed in June/July 2012 in the Po valley region in Italy as part of the Pan-European Gas-AeroSOls-climate interaction Study (PEGASOS). A Zeppelin NT was used as an airborne platform for measurements of HOx radical concentrations and total OH reactivity (kOH) applying a remotely controlled Laser Induced Fluorescence (LIF) instrument. In addition a comprehensive set of other trace gases (O3, CO, NO, NO2, HCHO, HONO, VOCs), photolysis frequencies, particle number concentration, and meteorological parameters were measured. During the morning hours, a layered atmospheric structure with vertical gradients in trace gas concentrations was observed. In altitudes larger than 600 m above ground, air masses with low trace gas concentrations (NOx < 500 ppt, kOH < 3 s-1) were probed, whereas air masses in altitudes below 100 m above ground were influenced by ground emissions resulting in higher trace gas concentrations (NOx > 6 ppb, kOH > 6 s-1). The airship Zeppelin NT was used to perform localized height profiles between 75 and 900 m above ground in order to investigate the influence of these trace gas gradients on HOx radical concentrations. Due to changing chemical conditions, the measured OH concentration shows a variability with height up to a factor of 2.5 and for the measured HO2 concentration up to a factor of 5. Additionally, we present box model calculations of HOx to identify the processes driving the radical chemistry and its change in concentration with height.

  16. Boron Toxicity Causes Multiple Effects on Malus domestica Pollen Tube Growth

    PubMed Central

    Fang, Kefeng; Zhang, Weiwei; Xing, Yu; Zhang, Qing; Yang, Liu; Cao, Qingqin; Qin, Ling

    2016-01-01

    Boron is an important micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this toxicity is not known. This study aimed to evaluate the effect of boron toxicity on Malus domestica pollen tube growth and its possible regulatory pathway. Our results showed that a high concentration of boron inhibited pollen germination and tube growth and led to the morphological abnormality of pollen tubes. Fluorescent labeling coupled with a scanning ion-selective electrode technique detected that boron toxicity could decrease [Ca2+]c and induce the disappearance of the [Ca2+]c gradient, which are critical for pollen tube polar growth. Actin filaments were therefore altered by boron toxicity. Immuno-localization and fluorescence labeling, together with fourier-transform infrared analysis, suggested that boron toxicity influenced the accumulation and distribution of callose, de-esterified pectins, esterified pectins, and arabinogalactan proteins in pollen tubes. All of the above results provide new insights into the regulatory role of boron in pollen tube development. In summary, boron likely plays a structural and regulatory role in relation to [Ca2+]c, actin cytoskeleton and cell wall components and thus regulates Malus domestica pollen germination and tube polar growth. PMID:26955377

  17. Boron Toxicity Causes Multiple Effects on Malus domestica Pollen Tube Growth.

    PubMed

    Fang, Kefeng; Zhang, Weiwei; Xing, Yu; Zhang, Qing; Yang, Liu; Cao, Qingqin; Qin, Ling

    2016-01-01

    Boron is an important micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this toxicity is not known. This study aimed to evaluate the effect of boron toxicity on Malus domestica pollen tube growth and its possible regulatory pathway. Our results showed that a high concentration of boron inhibited pollen germination and tube growth and led to the morphological abnormality of pollen tubes. Fluorescent labeling coupled with a scanning ion-selective electrode technique detected that boron toxicity could decrease [Ca(2+)]c and induce the disappearance of the [Ca(2+)]c gradient, which are critical for pollen tube polar growth. Actin filaments were therefore altered by boron toxicity. Immuno-localization and fluorescence labeling, together with fourier-transform infrared analysis, suggested that boron toxicity influenced the accumulation and distribution of callose, de-esterified pectins, esterified pectins, and arabinogalactan proteins in pollen tubes. All of the above results provide new insights into the regulatory role of boron in pollen tube development. In summary, boron likely plays a structural and regulatory role in relation to [Ca(2+)]c, actin cytoskeleton and cell wall components and thus regulates Malus domestica pollen germination and tube polar growth. PMID:26955377

  18. In vivo prompt gamma neutron activation analysis for the screening of boron-10 distribution in a rabbit knee: a simulation study

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Clackdoyle, R.; Shortkroff, S.; Yanch, J.

    2008-05-01

    Boron neutron capture synovectomy (BNCS) is under development as a potential treatment modality for rheumatoid arthritis (RA). RA is characterized by the inflammation of the synovium (the membrane lining articular joints), which leads to pain and a restricted range of motion. BNCS is a two-part procedure involving the injection of a boronated compound directly into the diseased joint followed by irradiation with a low-energy neutron beam. The neutron capture reactions taking place in the synovium deliver a local, high-linear energy transfer (LET) dose aimed at destroying the inflamed synovial membrane. For successful treatment via BNCS, a boron-labeled compound exhibiting both high synovial uptake and long retention time is necessary. Currently, the in vivo uptake behavior of potentially useful boronated compounds is evaluated in the knee joints of rabbits in which arthritis has been induced. This strategy involves the sacrifice and dissection of a large number of animals. An in vivo 10B screening approach is therefore under investigation with the goal of significantly reducing the number of animals needed for compound evaluation via dissection studies. The 'in vivo prompt gamma neutron activation analysis' (IVPGNAA) approach uses a narrow neutron beam to irradiate the knee from several angular positions following the intra-articular injection of a boronated compound whose uptake characteristics are unknown. A high-purity germanium detector collects the 478 keV gamma photons produced by the 10B capture reactions. The 10B distribution in the knee is then reconstructed by solving a system of simultaneous equations using a weighted least squares algorithm. To study the practical feasibility of IVPGNAA, simulation data were generated with the Monte Carlo N-particle transport code. The boron-containing region of a rabbit knee was partitioned into 8 compartments, and the 10B prompt gamma signals were tallied from 16 angular positions. Results demonstrate that for this level of spatial resolution, an estimate of 10B distribution inside the joint can be obtained to within 10% uncertainty, under ideal conditions. Variations of the anatomic dimensions among individual rabbit knees and potential knee positioning errors will result in an uncertainty of over 20%. IVPGNAA thus provides sufficient resolution and quantification regarding the in vivo uptake characteristics of boronated pharmaceuticals to serve as a useful means of screening new compounds of potential use in BNCS.

  19. Intra-Fuel Cell Stack Measurements of Transient Concentration Distributions

    SciTech Connect

    Partridge Jr, William P; Toops, Todd J; Green Jr, Johney Boyd; Armstrong, Timothy R.

    2006-01-01

    Intra-fuel-cell measurements are required to understand detailed fuel-cell chemistry and physics, validate models, optimize system design and control, and realize enhanced efficiency regimes; in comparison, conventional integrated fuel-cell supply and effluent measurements are fundamentally limited in value. Intra-reactor measurements are needed for all fuel cell types. This paper demonstrates the ability of a capillary-inlet mass spectrometer to resolve transient species distributions within operating polymer-electrolyte-membrane (PEM) fuel cells and at temperatures typical of solid-oxide fuel cells (SOFC). This is the first such demonstration of a diagnostic that is sufficiently minimally invasive as to allow measurements throughout an operating fuel cell stack. Measurements of transient water, hydrogen, oxygen and diluent concentration dynamics associated with fuel-cell load switching suggest oxygen-limited chemistry. Intra-PEM fuel cell measurements of oxygen distribution at various fuel-cell loads are used to demonstrate concentration gradients, non-uniformities, and anomalous fuel cell operation.

  20. Vertical distribution of number concentration and size distribution of atmospheric aerosols over the central United States

    NASA Astrophysics Data System (ADS)

    Kim, Young J.; Boatman, J. F.

    1990-09-01

    Aircraft measurements of trace gases and atmospheric aerosols were performed over the central United States during four research field periods in 1988 as a part of the Central U.S. RADM Test and Assessment Intensives (CURTAIN). Aerosol size distributions were measured at six altitudes between 700 and 3200 m above sea level over the size range 0.1-32 micrometers, using two Particle Measuring Systems (PMS) probes; an active scattering aerosol spectrometer probe (ASASP) and a forward scattering spectrometer probe (FSSP), mounted on the wings of the NOAA King Air research aircraft. The FSSP data were first corrected using a scheme which accounts for the effects of the probe's electronic response time and nonuniformity in the laser beam intensity profile on the measured aerosol size spectra. Vertical profiles of the average aerosol concentration show seasonal characteristics, with maximum concentrations during summer and minimum concentrations during winter. In summer, the aerosol number concentration in the fme. particle mode is rather constant about 2,000 cm-3 up to about 1900 m asl level. Number concentration of the soil. derived aerosols in the coarse-particle mode is maximized during spring. The measured aerosol number size distributions exhibit typically bimodal distributions for both boundary layer and free tropospheric aerosols. Each measured number size distribution is approximated with a sum of two lognormal distributions using a lognormal fitting routine. The aerosol size distribution data measured in the boundary layer and in the free troposphere are compared with the LOWTRAN 'Rural' aerosol model and Tropospheric aerosol model, respectively.

  1. Impact of boron dilution accidents on low boron PWR safety

    SciTech Connect

    Papukchiev, A.; Liu, Y.; Schaefer, A.

    2006-07-01

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

  2. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1995-10-03

    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.

  3. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-03-18

    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.

  4. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-08-05

    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.

  5. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1995-10-03

    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.

  6. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-03-18

    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.

  7. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-08-05

    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.

  8. Spectrally-resolved measurement of concentrated light distributions for Fresnel lens concentrators.

    PubMed

    Besson, P; White, P McVey; Dominguez, C; Voarino, P; Garcia-Linares, P; Lemiti, M; Schriemer, H; Hinzer, K; Baudrit, M

    2016-01-25

    A test method that measures spectrally resolved irradiance distribution for a concentrator photovoltaic (CPV) optical system is presented. In conjunction with electrical I-V curves, it is a means to visualize and characterize the effects of chromatic aberration and nonuniform flux profiles under controllable testing conditions. The indoor characterization test bench, METHOD (Measurement of Electrical, Thermal and Optical Devices), decouples the temperatures of the primary optical element (POE) and the cell allowing their respective effects on optical and electrical performance to be analysed. In varying the temperature of the POE, the effects on electrical efficiency, focal distance, spectral sensitivity, acceptance angle and multi-junction current matching profiles can be quantified. This work presents the calibration procedures to accurately image the spectral irradiance distribution of a CPV system and a study of system behavior over lens temperature. PMID:26832591

  9. GROWTH RESPONSE AND SELENIUM AND BORON DISTRIBUTION IN BROCCOLI VARIETIES IRRIGATED WITH POOR QUALITY WATER.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many drainage waters can be used successfully to grow selected crops without long-term consequences to crops and soils. Certain ions in saline waters can be specifically toxic to plants, if they accumulate to toxic concentrations within the plants tissues. Of particular concern in the San Joaquin ...

  10. Boron cosmochemistry

    NASA Technical Reports Server (NTRS)

    Curtis, D. B.; Gladney, E. S.

    1984-01-01

    The assumption that boron is a moderately volatile element is examined. It was demonstrated that interior pieces of chondrites contain significantly less boron than had been thought to be indigenous to this type of meteorite. The mean and range of boron abundances in 16 internal pieces of 10 chondrites were significantly smaller than in 126 pieces of 40 chondrites with unknown terrestrial histories. A new value of the cosmic abundance of boron was determined using the geometric average of the results from interior pieces of 10 chondrites. Based upon the thermodynamic assessment of the cosmochemical properties of boron by Cameron, et al. Anders and Ebihara assumed that boron was a moderately volatile element. They renormalized the data of Curtis et al. to a chondrule free basis and thus inferred that the cosmic abundance of boron was about 3 times greater than that proposed by Curtis, et al. To resolve these differences in data, the relative abundances of several elements including boron were measured in 38 carefully prepared interior pieces of 26 different chondrites. Correlation between boron and sulfur abundances, indicate that, contrary to the conclusions of Cameron, et al., boron is not a moderately volatile element.

  11. Minimum inhibitory concentration distribution in environmental Legionella spp. isolates.

    PubMed

    Sandalakis, Vassilios; Chochlakis, Dimosthenis; Goniotakis, Ioannis; Tselentis, Yannis; Psaroulaki, Anna

    2014-12-01

    In Greece standard tests are performed in the watering and cooling systems of hotels' units either as part of the surveillance scheme or following human infection. The purpose of this study was to establish the minimum inhibitory concentration (MIC) distributions of environmental Legionella isolates for six antimicrobials commonly used for the treatment of Legionella infections, by MIC-test methodology. Water samples were collected from 2004 to 2011 from 124 hotels from the four prefectures of Crete (Greece). Sixty-eight (68) Legionella isolates, comprising L. pneumophila serogroups 1, 2, 3, 5, 6, 8, 12, 13, 15, L. anisa, L. rubrilucens, L. maceachernii, L. quinlivanii, L. oakridgensis, and L. taurinensis, were included in the study. MIC-tests were performed on buffered charcoal yeast extract with α-ketoglutarate, L-cysteine, and ferric pyrophosphate. The MICs were read after 2 days of incubation at 36 ± 1 °C at 2.5% CO2. A large distribution in MICs was recorded for each species and each antibiotic tested. Rifampicin proved to be the most potent antibiotic regardless of the Legionella spp.; tetracycline appeared to have the least activity on our environmental isolates. The MIC-test approach is an easy, although not so cost-effective, way to determine MICs in Legionella spp. These data should be kept in mind especially since these Legionella species may cause human disease. PMID:25473976

  12. Trace Elements concentration and distribution across the Lake Chad Basin

    NASA Astrophysics Data System (ADS)

    Ndunguru, G. G.; Goni, I. B.; Mulugeta, V.; Grindley, J.; Banks, M. L.; Lee, J.; Adegoke, J. O.

    2009-12-01

    The Lake Chad, which is the largest Lake in West Africa, is situated between the latitude 12 and 14 north and longitude 130 east of the Southern fringe of the Sahara Desert. About 25 % of the Lake Chad lies within Nigeria, while the Republic of Cameroon, Chad and Niger share the rest of it. Lake Chad is completely landlocked and has no outlets; therefore loss of water is mainly through high rates of evaporation unlike similar Lakes in other parts of the World. The Lake Chad waters are fresh and of good quality with very low salt content which makes it suitable for irrigated agriculture. This study was carried out from upper stream to lower stream leading from Kano to the Damaturu region which is one of several water bodies that supply Lake Chad. Soil samples were collected from over seventy five sites and analyzed for ten Trace Elements(Be, Cd, Co, Cu, Mn,Fe, Mo, Pb, Zn, and Cr) using the Inductively Coupled Plasma (ICP)-OES. Assessment and Monitoring of Trace Elements concentrations are vital because they impact environment and can affect the human healthy. Since little is known about the Trace Elements status in Lake Chad Basin. The result in this study provides baseline information on the distribution and concentration of Trace Elements along the Lake Chad Basin.

  13. Reducing Boron Toxicity by Microbial Sequestration

    SciTech Connect

    Hazen, T.; Phelps, T.J.

    2002-01-01

    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.

  14. Methods for boron delivery to mammalian tissue

    DOEpatents

    Hawthorne, M. Frederick; Feaks, Debra A.; Shelly, Kenneth J.

    2003-01-01

    Boron neutron capture therapy can be used to destroy tumors. This treatment modality is enhanced by delivering compounds to the tumor site where the compounds have high concentrations of boron, the boron compounds being encapsulated in the bilayer of a liposome or in the bilayer as well as the internal space of the liposomes. Preferred compounds, include carborane units with multiple boron atoms within the carborane cage structure. Liposomes with increased tumor specificity may also be used.

  15. Direct assessment of mantle boron and lithium contents and distribution by SIMS analyses of peridotite minerals

    NASA Astrophysics Data System (ADS)

    Ottolini, Luisa; Le Fèvre, Brieuc; Vannucci, Riccardo

    2004-11-01

    The importance of Li and B geochemistry has long been recognised, owing specifically to their characteristic behaviours during processes involving fluid phases. However, the lack of a set of validated reference data for the "normal" Earth mantle has hampered the development of models for Li and B metasomatic effects on mantle rocks. In particular, the concentration of B in the mantle is still a matter of debate. An estimate of 0.1 ppm B seems to be consistent as a source for non-arc basalts, but to date such data have not been directly confirmed. Li and B literature contents for peridotites are derived from samples whose non-metasomatized character has not been established for both elements, due to the aforementioned lack of a comprehensive metasomatism model for Li and B. We have looked at two groups of mantle rocks, with and without clear compositional evidence that they are metasomatized. The latter rocks provide the best constraints on "normal" mantle B and Li contents. We propose a diagnostic diagram based on (Ce/B) vs. (Li/Yb) as measured by SIMS in peridotite clinopyroxenes, which is useful in identifying metasomatized samples. After discovering samples with no metasomatic alteration, which are considered representative of the "normal" mantle, we derived for each mantle mineral phase (ol, opx, cpx and sp) the Mg#, Li and B partial-melting evolution trends. Additionally, considering that the "normal" mantle rocks have evolved through partial melting only, we assessed Li and B contents in the parental mantle of our samples, and assumed that the calculated values (1.6-1.8 ppm Li and 0.07-0.10 ppm B) are representative of the contents in MORB mantle sources. These new data are consistent with current melting models of fertile peridotites.

  16. Silicon nanocrystals with high boron and phosphorus concentration hydrophilic shell—Raman scattering and X-ray photoelectron spectroscopic studies

    SciTech Connect

    Fujii, Minoru Sugimoto, Hiroshi; Hasegawa, Masataka; Imakita, Kenji

    2014-02-28

    Boron (B) and phosphorus (P) codoped silicon (Si) nanocrystals, which exhibit very wide range tunable luminescence due to the donor to acceptor transitions and can be dispersed in polar liquids without organic ligands, are studied by Raman scattering and X-ray photoelectron spectroscopies. Codoped Si nanocrystals exhibit a Raman spectrum significantly different from those of intrinsic ones. First, the Raman peak energy is almost insensitive to the size and is very close to that of bulk Si crystal in the diameter range of 2.7 to 14 nm. Second, the peak is much broader than that of intrinsic ones. Furthermore, an additional broad peak, the intensity of which is about 20% of the main peak, appears around 650 cm{sup −1}. The peak can be assigned to local vibrational modes of substitutional B and B-P pairs, B clusters, B-interstitial clusters, etc. in Si crystal. The Raman and X-ray photoelectron spectroscopic studies suggest that a crystalline shell heavily doped with these species is formed at the surface of a codoped Si nanocrystal and it induces the specific properties, i.e., hydrophilicity, high-stability in water, high resistance to hydrofluoric acid, etc.

  17. Sensitivity of regional ozone concentrations to temporal distribution of emissions

    NASA Astrophysics Data System (ADS)

    Tao, Zhining; Larson, Susan M.; Williams, Allen; Caughey, Michael; Wuebbles, Donald J.

    Temporal representations of emissions bear large uncertainty. Before any costly efforts are undertaken to improve the accuracy of temporal emission profiles, however, the impact of their uncertainty on predictions of surface O 3 concentrations should be examined. In this study, a 3-D air quality modeling system was used to probe the sensitivity of regional surface O 3 concentrations to temporal allocation of emissions over the continental US. The raw emissions inventory was processed using SMOKE and was segmented into hourly intervals using both "time-varying" and "uniform" temporal profiles of anthropogenic sources. Our simulation results show that, on average and with the grid resolution (90 km) used, regional daytime O 3 concentrations are not sensitive to changes in the temporal allocation of emissions, while nighttime O 3 concentrations are lower under "uniform" profiles than under "time-varying" profiles.

  18. Artificial neural networks to evaluate the boron concentration decreasing profile in blood-BPA samples of BNCT patients.

    PubMed

    García-Reiriz, Alejandro; Magallanes, Jorge; Zupan, Jure; Líberman, Sara

    2011-12-01

    For the prediction of decay concentration profiles of the p-boronophenylalanine (BPA) in blood during BNCT treatment, a method is suggested based on Kohonen neural networks. The results of a model trained with the concentration profiles from the literature are described. The prediction of the model was validated by the leave-one-out method. Its robustness shows that it is mostly independent on small variations. The ability to fit retrospective experimental data shows an uncertainty lower than the two compartment model used previously. PMID:21592804

  19. Distribution and concentration of suspended matter in Delaware Bay

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator); Philpot, W.

    1977-01-01

    The author has identified the following significant results. The problem of remote sensing of suspended matter in water was analyzed in terms of the single-scattering albedo, and a semiempirical relationship between satellite radiance measurements and the concentration of suspended matter in the water was developed. The relationship was tested using data from the 7 July 1973 LANDSAT overpass of Delaware Bay with good results. Suspended sediment concentration maps for the entire Delaware Bay were prepared using radiance values extracted from LANDSAT MSS imagery and correlating them with ground truth samples collected from boats and helicopter.

  20. Simultaneous determination of antimony and boron in beverage and dairy products by flame atomic absorption spectrometry after separation and pre-concentration by cloud-point extraction.

    PubMed

    Altunay, Nail; Grkan, Ramazan

    2016-02-01

    A new cloud-point extraction (CPE) method was developed for the pre-concentration and simultaneous determination of Sb(III) and B(III) by flame atomic absorption spectrometry (FAAS). The method was based on complexation of Sb(III) and B(III) with azomethine-H in the presence of cetylpyridinium chloride (CPC) as a signal-enhancing agent, and then extraction into the micellar phase of Triton X-114. Under optimised conditions, linear calibration was obtained for Sb(III) and B(III) in the concentration ranges of 0.5-180 and 2.5-600 ?gl(-1) with LODs of 0.15 and 0.75 ?gl(-1), respectively. Relative standard deviations (RSDs) (25 and 100 ?gl(-1) of Sb(III) and B(III), n=6) were in a range of 2.1-3.8% and 1.9-2.3%, respectively. Recoveries of spiked samples of Sb(III) and B(III) were in the range of 98-103% and 99-102%, respectively. Measured values for Sb and B in three standard reference materials were within the 95% confidence limit of the certified values. Also, the method was used for the speciation of inorganic antimony. Sb(III), Sb(V) and total Sb were measured in the presence of excess boron before and after pre-reduction with an acidic mixture of KI-ascorbic acid. The method was successfully applied to the simultaneous determination of total Sb and B in selected beverage and dairy products. PMID:26667090

  1. Hydrogen concentration and distribution in high-purity germanium crystals

    SciTech Connect

    Hansen, W.L.; Haller, E.E.; Luke, P.N.

    1981-10-01

    High-purity germanium crystals used for making nuclear radiation detectors are usually grown in a hydrogen ambient from a melt contained in a high-purity silica crucible. The benefits and problems encountered in using a hydrogen ambient are reviewed. A hydrogen concentration of about 2 x 10/sup 15/cm/sup -3/ has been determined by growing crystals in hydrogen spiked with tritium and counting the tritium ..beta..-decays in detectors made from these crystals. Annealing studies show that the hydrogen is strongly bound, either to defects or as H/sub 2/ with a dissociation energy > 3 eV. This is lowered to 1.8 eV when copper is present. Etching defects in dislocation-free crystals grown in hydrogen have been found by etch stripping to have a density of about 1 x 10/sup 7/ cm/sup -3/ and are estimated to contain 10/sup 8/ H atoms each.

  2. Silica and boron-containing ultraphosphate laser glass with low concentration quenching and improved thermal shock resistance

    DOEpatents

    Cook, Lee M.; Stokowski, Stanley E.

    1987-04-28

    Neodymium-doped phosphate glasses having a refractive index, nd>1.520; an Abbe number, Vd, <60; a density <3.0 g/cm.sup.3, a thermal expansion coefficient, .alpha., .ltoreq.110.times.10.sup.-7 .degree.C..sup.-1 ; a Young's Modulus, E, <70.times.10.sup.3 N/mm.sup.2 ; a Poisson's Ratio, .nu., <0.28; a thermal conductivity, K, >0.5 W/m.multidot.K, a thermal FOM=(1-.nu.).multidot.K/.alpha.E>0.7, consisting essentially of, in mol. %: P.sub.2 O.sub.5 : 40-70% SiO.sub.2 : 0-20% B.sub.2 O.sub.3 : 5-20% Sum SiO.sub.2 +B.sub.2 O.sub.3 : 5-35% Sum Li.sub.2 O+Na.sub.2 O+K.sub.2 O: 5-20% Sum La.sub.2 O.sub.3 +Nd.sub.2 O.sub.3 : 3-10% Sum MgO+CaO+SrO+BaO+ZnO: 0-10% and preferably containing an amount of Nd.sub.2 O.sub.3 effective for laser activity having an emission cross-section, .sigma., >3.5.times.10.sup.-20 cm.sup.2 ; a fluorescence linewidth (.DELTA..lambda..sub.f1)<23.5 nm; a first e-folding time of the Nd.sup.3+ fluorescence at 0.5 wt. % Nd.sub.2 O.sub.3 >375 .mu.sec, and a first e-folding time of the Nd.sup.3+ fluorescence at 10 wt. % >175 .mu.sec at 10 wt. %, have very low self-concentration quenching rates.

  3. Direct current sputtering of boron from boron/boron mixtures

    DOEpatents

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

    1994-12-13

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

  4. Boron deposition from fused salts. Final report

    SciTech Connect

    Smith, M.L.

    1980-08-01

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

  5. Boron removal from geothermal waters by electrocoagulation.

    PubMed

    Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar; Yilmaz, M Tolga; Paluluoğlu, Cihan

    2008-05-01

    Most of the geothermal waters in Turkey contain extremely high concentration of boron when they are used for irrigation. The use of geothermal waters for irrigation can results in excess amount deposition of boron in soil. On the other hand, a minimal boron concentration is required for irrigational waters. In this study, electrocoagulation (EC) was selected as a treatment process for the removal of boron from thermal waters obtained from Ilica-Erzurum in Turkey. Current density (CD), pH of solution and temperature of solution were selected as operational parameters. The results showed that boron removal efficiency increased from pH 4.0 to 8.0 and decreased at pH 10.0. Although boron removal efficiency was highest at pH 8.0, energy consumption was very high at this pH value compared to other pH intervals. Boron removal efficiency reached to 95% with increasing current density from 1.5 to 6.0 mA/cm(2), but energy consumption was also increased in this interval. At higher temperatures of solution, such as 313 and 333 K, boron removal efficiency increased. At optimum conditions, boron removal efficiency in geothermal water reached up to 95%. PMID:17904734

  6. Characterization of electrodeposited elemental boron

    SciTech Connect

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

    2008-07-15

    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.

  7. [Effect of different distribution of components concentration on the accuracy of quantitative spectral analysis].

    PubMed

    Li, Gang; Zhao, Zhe; Wang, Hui-Quan; Lin, Ling; Zhang, Bao-Ju; Wu, Xiao-Rong

    2012-07-01

    In order to discuss the effect of different distribution of components concentration on the accuracy of quantitative spectral analysis, according to the Lambert-Beer law, ideal absorption spectra of samples with three components were established. Gaussian noise was added to the spectra. Correction and prediction models were built by partial least squares regression to reflect the unequal modeling and prediction results between different distributions of components. Results show that, in the case of pure linear absorption, the accuracy of model is related to the distribution of components concentration. Not only to the component we focus on, but also to the non-tested components, the larger covered and more uniform distribution is a significant point of calibration set samples to establish a universal model and provide a satisfactory accuracy. This research supplies a theoretic guidance for reasonable choice of samples with suitable concentration distribution, which enhances the quality of model and reduces the prediction error of the predict set. PMID:23016350

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

    USGS Publications Warehouse

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

    2004-01-01

    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.

  9. [Spatio-temporal distribution of chlorophyll a concentration and its estimation in Taihu Lake].

    PubMed

    Le, Cheng-Feng; Li, Yun-Mei; Sun, De-Yong; Wang, Hai-Jun; Huang, Chang-Chun

    2008-03-01

    The temporal and spatial distribution of chlorophyll a concentration in Taihu Lake was analyzed using the data measured from January to October in 2005. Otherwise, chlorophyll a retrieval model was built using the synchronous spectrum data obtained in different season to evaluate the effect of chlorophyll a concentration temporal and spatial variation on the retrieval model. Firstly, temporal distribution of chlorophyll a concentration was analyzed. Then, chlorophyll a concentration was induced by Inverse Distance Weight method. Lastly, the chlorophyll a concentration estimation models based on spring, summer, autumn and different trophic states were built. An obvious spatial-temporal distribution was found for chlorophyll a concentration in Taihu. Chlorophyll a concentration had the maximal value in summer and the minimal value in winter,and the average chlorophyll a concentration was 56.29 microg/L, 13.61 microg/L respectively. Due to the effect of autumn, the average chlorophyll a concentration in autumn was higher than that in spring, and the average chlorophyll a concentration was 26.43 microg/L, 34.78 microg/L respectively. Marked spatial difference for chlorophyll a concentration was found in summer,while in winterthe spatial variation was ambiguous. The spatial variation in autumn was greater than that in spring as influenced by summer. Spatially, the variation in north area was greater than those in the other areas and the south area had less variation during the year. Because of the different chlorophyll a concentration, different season had different retrieval model. Band-ratio had better retrieval result in spring and autumn as there were lower concentration and less variation correspondingly. While in summer, because of the high chlorophyll a concentration and great spatial variation, among the arithmetic built in summer, the differential arithmetic was the optimal model, and the difference of Chl-a concentration retrieval model of different trophic state was minor. PMID:18649517

  10. [Spatiotemporal distribution of negative air ion concentration in urban area and related affecting factors: a review].

    PubMed

    Huang, Xiang-Hua; Wang, Jian; Zeng, Hong-Da; Chen, Guang-Shui; Zhong, Xian-Fang

    2013-06-01

    Negative air ion (NAI) concentration is an important indicator comprehensively reflecting air quality, and has significance to human beings living environment. This paper summarized the spatiotemporal distribution features of urban NAI concentration, and discussed the causes of these features based on the characteristics of the environmental factors in urban area and their effects on the physical and chemical processes of NAI. The temporal distribution of NAI concentration is mainly controlled by the periodic variation of solar radiation, while the spatial distribution of NAI concentration along the urban-rural gradient is mainly affected by the urban aerosol distribution, underlying surface characters, and urban heat island effect. The high NAI concentration in urban green area is related to the vegetation life activities and soil radiation, while the higher NAI concentration near the water environment is attributed to the water molecules that participate in the generation of NAI through a variety of ways. The other environmental factors can also affect the generation, life span, component, translocation, and distribution of NAI to some extent. To increase the urban green space and atmospheric humidity and to maintain the soil natural attributes of underlying surface could be the effective ways to increase the urban NAI concentration and improve the urban air quality. PMID:24066568

  11. Features of Distribution of Mercurian Concentric Basins on the Base of Messenger Data

    NASA Astrophysics Data System (ADS)

    Rodionova, Zhanna; Blue, Jennifer

    MESSENGER images were investigated to expose the distribution of concentric basins on the surface of Mercury. We revealed 49 such objects with outer diameters from 64 km to 488 km, some of which have been formally named (e.g., Bach (214 km), Homer (319 km), Rachmaninov (306 km), Renoir (220 km), Chekhov (194 km), etc.). Fourteen concentric basins are unnamed. Concentric basins share the following common features: the diameter of the outer ridge is twice that of the inner ridge; the surface of the central depression is covered with a fewer number of craters than the surface between the inner and outer ridges; and chains of small craters and valleys usually surround such concentric basins. A histogram of the distribution of these basin dimensions shows that diameters from 160 km to 170 km and 190 km to 220 km are prevalent for concentric basins. About 70% of all concentric basins on Mercury are located in marginal zones between plains and highlands. We have compiled a map of the distribution of concentric basins on the Mercurian surface. It shows that the frequency of concentric basins in the western hemisphere is three times greater than the frequency in the eastern hemisphere. The comparison of concentric basins on Mercury, Moon and Mars is now complete.

  12. Very high energy implants of boron into silicon

    NASA Astrophysics Data System (ADS)

    La Ferla, A.; Rimini, E.; Ciavola, G.; Ferla, G.

    1989-02-01

    Boron ions of energy in the 15-50 MeV range and doses in the 10 13-10 15 cm -2 range were implanted into 1 kΩ cm n-type <100> silicon wafers. The samples, after annealing at 800-1250 ° C, were analyzed by spreading resistance profilometry. A simple model was used to predict the range distribution of the implanted ions. The measured projected ranges compare moderately well with calculations, while the concentration in the long tail up to the surface is two to three orders of magnitude higher than that calculated. Annealing at 1250 ° C for 24 h of multiple energy boron implants gives rise to a nearly flat profile with a concentration of 5 × 10 16 cm -3 over 100 μm. A diode with a junction depth of about 120 μm was realized.

  13. Influence of drop size distribution function on simulated ground precipitation for different cloud droplet number concentrations

    NASA Astrophysics Data System (ADS)

    Kovačević, Nemanja; Ćurić, Mladjen

    2015-05-01

    A cloud-resolving mesoscale model with a two-moment bulk microphysical scheme is used to perform cloud simulations for two different modes of the liquid water spectrum: a unified Khrgian-Mazin size distribution for the entire spectrum of drops and the monodisperse size distribution for cloud droplets with the exponential Marshall-Palmer distribution for raindrops. The cloud model calculates the mixing ratios and number concentrations of the six microphysical categories: raindrops, cloud ice, snow, graupel, frozen raindrops and hail. The cloud droplet number concentration was prescribed. The main purpose of this sensitivity study was to analyse the differences in simulated surface precipitation (rain and hail) for the two assumed approaches with different values of cloud droplet number concentration. The study showed that there are significant differences in the occurrence, amount and spatial distribution of accumulated precipitation at the surface. It can be noted that the unified Khrgian-Mazin size distribution is generally more sensitive to changes in the cloud droplet number concentration than an alternative approach. The rain showers and cloud splitting are well simulated with the unified Khrgian-Mazin size distribution, especially for smaller values of cloud droplet number concentration.

  14. Intensity distribution in cylindrical-circular receivers for nonperfect cylindrical-parabolic concentrators

    SciTech Connect

    Nicols, R.O.

    1985-08-15

    A 2-D optical analysis is described that allows determination of the intensity distribution on a circular cylinder located in the focal zone of nonperfect concentrators. We call nonperfect concentrators those in which the normal to each differential element of the specular surface departs from its correct position by an angle epsilon, the possible values of which follow a Gaussian distribution of mean value epsilon-bar and standard deviation sigma. The analysis is based on a previous one developed to calculate the intensity distribution at the receiver plane of nonperfect cylindrical concentrators. The analysis permits the consideration of circular receivers displaced from the focus by distance delta/sub f/ in any direction and directions of the incident rays nonparallel to the parabola's symmetry plane. Results for different sets of parameters characterizing the behavior of a given concentrator are shown and compared.

  15. Some aspects of statistical distribution of trace element concentrations in biomedical samples

    NASA Astrophysics Data System (ADS)

    Majewska, U.; Braziewicz, J.; Banaś , D.; Kubala-Kukuś , A.; Góź Dź , S.; Pajek, M.; Zadrozsolarna, M.; Jaskóla, M.; Czyzsolarewski, T.

    1999-04-01

    Concentrations of trace elements in biomedical samples were studied using X-ray fluorescence (XRF), total reflection X-ray fluorescence (TRXRF) and particle-induced X-ray emission (PIXE) methods. Used analytical methods were compared in terms of their detection limits and applicability for studying the trace elements in large populations of biomedical samples. In a result, the XRF and TRXRF methods were selected to be used for the trace element concentration measurements in the urine and woman full-term placenta samples. The measured trace element concentration distributions were found to be strongly asymmetric and described by the logarithmic-normal distribution. Such a distribution is expected for the random sequential process, which realistically models a level of trace elements in studied biomedical samples. The importance and consequences of this finding are discussed, especially in the context of comparison of the concentration measurements in different populations of biomedical samples.

  16. Spatial concentration distribution analysis of cells in electrode-multilayered microchannel by dielectric property measurement.

    PubMed

    Yao, Jiafeng; Kodera, Tatsuya; Obara, Hiromichi; Sugawara, Michiko; Takei, Masahiro

    2015-07-01

    The spatial concentration distribution of cells in a microchannel is measured by combining the dielectric properties of cells with the specific structure of the electrode-multilayered microchannel. The dielectric properties of cells obtained with the impedance spectroscopy method includes the cell permittivity and dielectric relaxation, which corresponds to the cell concentration and structure. The electrode-multilayered microchannel is constructed by 5 cross-sections, and each cross-section contains 5 electrode-layers embedded with 16 micro electrodes. In the experiment, the dielectric properties of cell suspensions with different volume concentrations are measured with different electrode-combinations corresponding to different electric field distributions. The dielectric relaxations of different cell concentrations are compared and discussed with the Maxwell-Wagner dispersion theory, and the relaxation frequencies are analysed by a cell polarization model established based on the Hanai cell model. Moreover, a significant linear relationship with AC frequency dependency between relative permittivity and cell concentration was found, which provides a promising way to on-line estimate cell concentration in microchannel. Finally, cell distribution in 1 cross-section of the microchannel (X and Y directions) was measured with different electrode-combinations using the dielectric properties of cell suspensions, and cell concentration distribution along the microchannel (Z direction) was visualized at flowing state. The present cell spatial sensing study provides a new approach for 3 dimensional non-invasive online cell sensing for biological industry. PMID:26392831

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

    SciTech Connect

    Agarwal, A.; Eaglesham, D.J.; Gossmann, H.J.; Pelaz, L.; Herner, S.B.; Jacobson, D.C.; Haynes, T.E.; Erokhin, Y.E.

    1998-05-03

    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.

  18. Boron nitride nanotubes

    DOEpatents

    Smith, Michael W.; Jordan, Kevin; Park, Cheol

    2012-06-06

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

  19. Boron Nitride Nanotubes

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  20. Boron doped nanostructured diamond films

    NASA Astrophysics Data System (ADS)

    Liang, Qi

    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.

  1. Silicon and boron differ in their localization and loading in bone☆

    PubMed Central

    Jugdaohsingh, Ravin; Pedro, Liliana D.; Watson, Abigail; Powell, Jonathan J.

    2014-01-01

    Silicon and boron share many similarities, both chemically and biochemically, including having similar effects on bone, although their mechanisms of action are not known. Here we compared the loading of silicon and boron into bone, their localization and how they are influenced by age (growth & development), to obtain further clues as to the biological effects of these elements and, especially, to see if they behave the same or not. Bone samples were obtained from two different studies where female Sprague Dawley rats had been maintained on a normal maintenance diet for up to 43 weeks. Total bone elemental levels were determined by ICP-OES following microwave assisted acid digestion. Silicon and boron levels in the decalcified bones (i.e. the collagen fraction) were also investigated. Silicon and boron showed marked differences in loading and in their localization in bone. Highest silicon and lowest boron concentrations were found in the under-mineralized bone of younger rats and lowest silicon and highest boron concentrations were found in the fully mineralized bone of the adult rat. Overall, however total bone silicon content increased with age, as did boron content, the latter mirroring the increase in calcium (mineral) content of bone. However, whereas silicon showed equal distribution in the collagen and mineral fractions of bone, boron was exclusively localized in the mineral fraction. These findings confirm the reported association between silicon and collagen, especially at the early stages of bone mineralization, and show that boron is associated with the bone mineral but not connective tissues. These data suggest that silicon and boron have different biological roles and that one is unlikely, therefore, to substitute for the other, or at least boron would not substitute for Si in the connective tissues. Finally, we noted that silicon levels in the mineral fraction varied greatly between the two studies, suggesting that one or more nutritional factor(s) may influence the loading of Si into the mineral fraction of bone. This and the nature of the interaction between Si and collagen deserve further attention. PMID:26665155

  2. Factors Controlling Droplet Concentration and Size Distribution in Clouds over Dominica

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  3. Flow distribution in parallel microfluidic networks and its effect on concentration gradient.

    PubMed

    Guermonprez, Cyprien; Michelin, Sébastien; Baroud, Charles N

    2015-09-01

    The architecture of microfluidic networks can significantly impact the flow distribution within its different branches and thereby influence tracer transport within the network. In this paper, we study the flow rate distribution within a network of parallel microfluidic channels with a single input and single output, using a combination of theoretical modeling and microfluidic experiments. Within the ladder network, the flow rate distribution follows a U-shaped profile, with the highest flow rate occurring in the initial and final branches. The contrast with the central branches is controlled by a single dimensionless parameter, namely, the ratio of hydrodynamic resistance between the distribution channel and the side branches. This contrast in flow rates decreases when the resistance of the side branches increases relative to the resistance of the distribution channel. When the inlet flow is composed of two parallel streams, one of which transporting a diffusing species, a concentration variation is produced within the side branches of the network. The shape of this concentration gradient is fully determined by two dimensionless parameters: the ratio of resistances, which determines the flow rate distribution, and the Péclet number, which characterizes the relative speed of diffusion and advection. Depending on the values of these two control parameters, different distribution profiles can be obtained ranging from a flat profile to a step distribution of solute, with well-distributed gradients between these two limits. Our experimental results are in agreement with our numerical model predictions, based on a simplified 2D advection-diffusion problem. Finally, two possible applications of this work are presented: the first one combines the present design with self-digitization principle to encapsulate the controlled concentration in nanoliter chambers, while the second one extends the present design to create a continuous concentration gradient within an open flow chamber. PMID:26487905

  4. Controls on boron and germanium distribution in the low-sulfur Amos coal bed, Western Kentucky coalfield, USA

    USGS Publications Warehouse

    Hower, J.C.; Ruppert, L.F.; Williams, D.A.

    2002-01-01

    The Duckmantian-aged Amos coal bed is a thin (<51 cm) coal bed that occurs in lobate southwest-trending pods separated by thin sandstones in the Western Kentucky coalfield. The coal bed, which is comprised of up to two benches and a rider coal, is low in ash yield (<6%) and sulfur content (<1%). The coal tends to be thin (<40 cm), but it was heavily mined in the 1980s because it could be combusted as mined. Geochemical analysis of the Amos coal bed shows higher concentrations of B and Ge than other Western Kentucky coal beds. High total B concentrations as well as high B/Be, both considered to be indicators of marine environments, increase toward the top of the coal bed. Most of the B values for the Amos samples range from 66 to 103 ppm (whole coal basis) indicating deposition in a brackish environment. High Ge concentrations in coals have been considered to be a function of seam thickness and proximity to the top and bottom of the coal bed. Thin coals, such as the Amos, are dominated by the coal bed margins and, therefore, have a tendency to have relatively high Ge concentrations. In the case of the Amos coal bed, the lower bench has a higher Ge content, suggesting that the substrate was a more important source of Ge than the roof rock. ?? 2002 Elsevier Science B.V. All rights reserved.

  5. [Airborne Fungal Aerosol Concentration and Distribution Characteristics in Air- Conditioned Wards].

    PubMed

    Zhang, Hua-ling; Feng, He-hua; Fang, Zi-liang; Wang, Ben-dong; Li, Dan

    2015-04-01

    The effects of airborne fungus on human health in the hospital environment are related to not only their genera and concentrations, but also their particle sizes and distribution characteristics. Moreover, the mechanisms of aerosols with different particle sizes on human health are different. Fungal samples were obtained in medicine wards of Chongqing using a six-stage sampler. The airborne fungal concentrations, genera and size distributions of all the sampling wards were investigated and identified in detail. Results showed that airborne fungal concentrations were not correlated to the diseases or personnel density, but were related to seasons, temperature, and relative humidity. The size distribution rule had roughly the same for testing wards in winter and summer. The size distributions were not related with diseases and seasons, the percentage of airborne fungal concentrations increased gradually from stage I to stage III, and then decreased dramatically from stage V to stage VI, in general, the size of airborne fungi was a normal distribution. There was no markedly difference for median diameter of airborne fungi which was less 3.19 μm in these wards. There were similar dominant genera in all wards. They were Aspergillus spp, Penicillium spp and Alternaria spp. Therefore, attention should be paid to improve the filtration efficiency of particle size of 1.1-4.7 μm for air conditioning system of wards. It also should be targeted to choose appropriate antibacterial methods and equipment for daily hygiene and air conditioning system operation management. PMID:26164895

  6. Boron doping a semiconductor particle

    DOEpatents

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

    1998-06-09

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

  7. Boron doping a semiconductor particle

    DOEpatents

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

    1998-06-09

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

  8. Methods of forming boron nitride

    SciTech Connect

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

    2015-03-03

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

  9. The effect of concentrator field layout on the performance of point-focus distributed receiver systems

    NASA Technical Reports Server (NTRS)

    Pons, R. L.; Dugan, A. F.

    1984-01-01

    The effect of concentrator field layout on the technical-economic performance of a point-focusing distributed receiver (PFDR) solar thermal power plant is presented. The plant design is based on the small community prototype system currently under development for JPL/DOE; parabolic dish concentrators are employed, and small heat engines are used to generate electricity at each dish. The effect of field size, array proportions, dish-to-dish spacing and packing fraction (concentrator-land area ratio) are presented for typical PFDR layouts. Economic analyses are carried out to determine optimum packing fraction as a function of site cost.

  10. The effect of concentrator field layout on the performance of point-focus distributed receiver systems

    NASA Astrophysics Data System (ADS)

    Pons, R. L.; Dugan, A. F.

    1984-02-01

    The effect of concentrator field layout on the technical-economic performance of a point-focusing distributed receiver (PFDR) solar thermal power plant is presented. The plant design is based on the small community prototype system currently under development for JPL/DOE; parabolic dish concentrators are employed, and small heat engines are used to generate electricity at each dish. The effect of field size, array proportions, dish-to-dish spacing and packing fraction (concentrator-land area ratio) are presented for typical PFDR layouts. Economic analyses are carried out to determine optimum packing fraction as a function of site cost.

  11. Electrochemical apparatus for automatic measurement of carrier-concentration distribution in semiconductors

    SciTech Connect

    Belova, N.A.; Galchenkov, L.A.; Skvortsova, N.E.

    1986-06-01

    This paper describes apparatus for measuring the carrier-concentration depth (from 1 to 30-50 um) distribution of semiconductors in the concentration range of 10/sup 14/-10/sup 19/ cm/sup -3/. The measurement errors for concentration and depth are 10% and 5%. Measurements can be made in AgAs, InP, Si, and, with proper selection of the electrolyte, other semiconductors. Measurements are made automatically and the results are recorded with a plotter. Schematic diagrams are presented of the main units of the apparatus which include the capacitance meter, synchronous detector, potentiostat, automatic unit, and various circuits.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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 PM 10 (particulate matter sampled with a 50% cut-point of 10 μm) Federal Reference Method (FRM) monitors in lieu of total suspended particulate (TSP) monitors for some non-source-oriented monitoring. PM 10 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.

  13. Boron toxicity in the rare serpentine plant, Streptanthus morrisonii.

    PubMed

    Sage, R F; Ustin, S L; Manning, S J

    1989-01-01

    The release of boron-laden mist from the cooling towers of some geothermal power stations in northern California potentially threatens nearby populations of the rare serpentine plant, Streptanthus morrisonii F. W. Hoffm. To assess the tolerance of S. morrisonii to high levels of boron, the effect of boron on leaf condition, life history, germination rate, growth rate, allocation and photosynthesis was measured on plants grown in a greenhouse. Relative to other species, S. morrisonii was tolerant of excess boron. On serpentine soil, mild to moderate toxicity symptoms (older leaves exhibiting chlorosis and necrosis, but few leaves killed) were apparent when the boron concentration in applied nutrient solutions was 240-650 microm. Severe toxicity symptoms (significant leaf loss, young leaves with toxicity symptoms) were apparent when the applied solution was over 1000 microm boron. Above 1000 microm boron, S. morrisonii appeared unable to complete its life cycle. On a tissue basis, boron toxicity was first observed when leaf boron content was 40-90 micromol g(-1) dry weight. In leaves with severe boron toxicity (> 35% injury), the boron content was generally above 130 micromol g(-1) dry weight. These levels were an order of magnitude above the tissue boron content of plants in the field. Prior to the onset of pronounced boron toxicity symptoms, growth rate, allocation patterns, and photosynthesis were unaffected by high boron. These results indicate that inhibition of growth and photosynthesis occurred because of a loss of viable tissue due to boron injury, rather than a progressive decline as leaf boron levels increased. PMID:15092365

  14. Female offspring of rat dams fed low boron diets during pregnancy and lactation exhibit signs of the metabolic syndrome during early adulthood: increased body weight, & serum triglycerides and total cholesterol concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To expand on reports from this laboratory that low dietary boron may affect energy substrate utilization, we determined whether low dietary boron during early development promotes manifestation of the metabolic syndrome in adult offspring. Sprague-Dawley dams were fed either a boron-low (BL; ~0.1 mg...

  15. Pressure-dependent boron isotopic fractionation observed by column chromatography

    NASA Astrophysics Data System (ADS)

    Musashi, M.; Oi, T.; Matsuo, M.; Nomura, M.

    2007-12-01

    Boron isotopic fractionation factor ( S ) between boron taken up in strongly basic anion exchange resin and boron in aqueous solution was determined by breakthrough column chromatography at 5 and 17 MPa at 25°C, using 0.1 mmol/L boric acid solution as feed solution. The S values obtained were 1.018 and 1.012, respectively, which were smaller than the value reported by using the same chromatographic method at atmospheric pressure at 25°C with the boron concentration of 10 mmol/L, but were larger than the values at the same condition with much higher concentration of 100 and 501 mmol/L, indicating that borate-polymerization reducing the isotopic fractionation was negligible. However, calculations based on the theory of isotope distribution between two phases estimated that 21% (5MPa) and 47% (17MPa) of boron taken up in the resin phase was in the three-coordinated B(OH)3-form, instead of in the four-coordinated B(OH)4--form, at high pressures even with the very diluted solution. We discussed this discrepancy by introducing (1) hydration or (2) a partial molar volume difference between isotopic molecules. It was inferred that borate ions were partially dehydrated upon transfer from the solution phase to the resin phase at high pressures, which resulted in smaller S values compared with those at the atmospheric pressure. Alternatively, it was likely that the S value decreased with increasing pressure, because the difference of the partial isotopic molar volumes between 10B(OH)3 and 11B(OH)3 was larger than that between 10B(OH)4- and 11B(OH)4-. If either will be the case, the influence of a pressure upon the isotope effect may not be negligible for boron isotopic exchange equilibrium. This knowledge is crucial for the principle of the boron isotopic pH-metry reconstructing a chemical variation at the paleo-deep oceanic environment where the early life may have been evolved.

  16. Ecological risk assessment of a wetland exposed to boron

    SciTech Connect

    Powell, R.L.; Kimerle, R.A.; Coyle, G.T.; Best, G.R.

    1997-11-01

    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.

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

    PubMed

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

    2011-02-01

    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

  18. Studies on depth-dose-distribution controls by deuteration and void formation in boron neutron capture therapy.

    PubMed

    Sakurai, Yoshinori

    2004-08-01

    Physical studies on (i) replacement of heavy water for body water (deuteration), and (ii) formation of a void in human body (void formation) were performed as control techniques for dose distribution in a human head under neutron capture therapy. Simulation calculations were performed for a human-head-size cylindrical phantom using a two-dimensional transport calculation code for mono-energetic incidences of higher-energy epi-thermal neutrons (1.2-10 keV), lower-energy epi-thermal neutrons (3.1-23 eV) and thermal neutrons (1 meV to 0.5 eV). The deuteration was confirmed to be effective both in thermal neutron incidence and in epi-thermal neutron incidence from the viewpoints of improvement of the thermal neutron flux distribution and elimination of the secondary gamma rays. For the void formation, a void was assumed to be 4 cm in diameter and 3 cm in depth at the surface part in this study. It was confirmed that the treatable depth was improved almost 2 cm for any incident neutron energy in the case of the 10 cm irradiation field diameter. It was made clear that the improvement effect was larger in isotropic incidence than in parallel incidence, in the case that an irradiation field size was delimited fitting into a void diameter. PMID:15379019

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

    SciTech Connect

    Verbeke, Jerome M.; Chen, Allen S.; Vujic, Jasmina L.; Leung, Ka-Ngo

    2000-08-15

    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.

  20. Occurrence and distribution of selected heavy metals and boron in groundwater of the Gulf of Khambhat region, Gujarat, India.

    PubMed

    Upadhyaya, Devang; Survaiya, Mayur D; Basha, Shaik; Mandal, Subir K; Thorat, R B; Haldar, Soumya; Goel, Sangita; Dave, Himal; Baxi, Krushnakant; Trivedi, Rohit H; Mody, Kalpana H

    2014-03-01

    The concentration of selected heavy metals, like As, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn as well as B, was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) in groundwater samples from various locations in the Gulf of Khambhat (GoK), an inlet of the Arabian Sea in the state of Gujarat, India, during post-monsoon, winter, and pre-monsoon seasons in a year. Most heavy elements are characterized by low mobility under slightly alkaline and reducing conditions; concentrations in confined aquifers are smaller than the maximum permissible values for drinking water. The temporal changes indicate that a majority of metals is entering the aquifer during monsoon. Principle component analysis of the heavy metal data suggests that Co, Cu, Cd, and Zn are interrelated with each other and derived significantly from anthropogenic route, while input of Pb and Cr may be due to atmospheric deposition in the study area. Both weathering of rocks and anthropogenic input were found to be main sources of elements in the groundwater. The heavy metal levels in groundwaters of the GoK region in comparison with some of the European and Asian sites were higher; however, these metal levels were found to be comparable with few urban sites in the world. PMID:24293301

  1. Spatial distribution of livestock concentration areas and soil nutrients in pastures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Livestock frequently congregate at feeders, shades, or other sites on pastures, which severely disturbs soil and vegetation leading to erosion and nutrient runoff. Our objective was to determine the extent and spatial distribution of soil nutrients in livestock concentration areas on pastures and qu...

  2. Vertical profiles of black carbon concentration and particle number size distribution in the North China Plain

    NASA Astrophysics Data System (ADS)

    Ran, L.; Deng, Z.

    2013-12-01

    The vertical distribution of aerosols is of great importance to our understanding in the impacts of aerosols on radiation balance and climate, as well as air quality and public health. To better understand and estimate the effects of atmospheric components including trace gases and aerosols on atmospheric environment and climate, an intensive field campaign, Vertical Observations of trace Gases and Aerosols in the North China Plain (VOGA-NCP), was carried out from late July to early August 2013 over a rural site in the polluted NCP. During the campaign, vertical profiles of black carbon (BC) concentration and particle number size distribution were measured respectively by a micro-Aethalometer and an optical particle counter attached to a tethered balloon within 1000 m height. Meteorological parameters, including temperature, relative humidity, wind speed and wind direction, were measured simultaneously by a radiosonde also attached to the tethered balloon. Preliminary results showed distinct diurnal variations of the vertical distribution of aerosol total number concentration and BC concentration, following the development of the mixing layer. Generally, there was a well mixing of aerosols within the mixing layer and a sharp decrease above the mixing layer. Particularly, a small peak of BC concentrations was observed around 400-500 m height for several profiles. Further analysis would be needed to explain such phenomenon. It was also found that measured vertical profiles of BC using the filter-based method might be affected by the vertical distribution of relative humidity.

  3. ON THE PROPORTIONALITY OF FINE MASS CONCENTRATION AND EXTINCTION COEFFICIENT FOR BIMODAL SIZE DISTRIBUTIONS

    EPA Science Inventory

    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, with no dependence on th...

  4. Particle Size Concentration Distribution and Influences on Exhaled Breath Particles in Mechanically Ventilated Patients

    PubMed Central

    Chen, Yi-Fang; Huang, Sheng-Hsiu; Wang, Yu-Ling; Chen, Chun-Wan

    2014-01-01

    Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47–2,554.04 particles/breath (0.001–4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH2O) clearly exceeded those in patients with low PEEP (≤ 5 cmH2O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration. PMID:24475230

  5. Spatial concentration distribution model for short-range continuous gas leakage of small amount

    NASA Astrophysics Data System (ADS)

    Wang, Meirong; Wang, Lingxue; Li, Jiakun; Long, Yunting; Gao, Yue

    2012-06-01

    Passive infrared gas imaging systems have been utilized in the equipment leak detection and repair in chemical manufacturers and petroleum refineries. The detection performance mainly relates to the sensitivity of infrared detector, optical depth of gas, atmospheric transmission, wind speed, and so on. Based on our knowledge, the spatial concentration distribution of continuously leaking gas plays an important part in leak detection. Several computational model of gas diffusion were proposed by researchers, such as Gaussian model, BM model, Sutton model and FEM3 model. But these models focus on calculating a large scale gas concentration distribution for a great amount of gas leaks above over 100- meter height, and not applicable to assess detection limit of a gas imaging system in short range. In this paper, a wind tunnel experiment is designed. Under different leaking rate and wind speed, concentration in different spatial positions is measured by portable gas detectors. Through analyzing the experimental data, the two parameters σy(x) and σz (x) that determine the plume dispersion in Gaussian model are adjusted to produce the best curve fit to the gas concentration data. Then a concentration distribution model for small mount gas leakage in short range is established. Various gases, ethylene and methane are used to testify this model.

  6. Concentration and size distribution of total airborne microbes in hazy and foggy weather.

    PubMed

    Dong, Lijie; Qi, Jianhua; Shao, Congcong; Zhong, Xi; Gao, Dongmei; Cao, Wanwan; Gao, Jiawei; Bai, Ran; Long, Gaoyuan; Chu, Congcong

    2016-01-15

    Atmospheric bioaerosol particles were collected using a bioaerosol sampler from Oct. 2013 to Aug. 2014 in the coastal region of Qingdao. The total microbes were measured using an epifluorescence microscope after staining with DAPI (4',6-diamidino-2-phenylindole). The concentration of total airborne microbes showed seasonal variation, with the highest value in winter and the lowest in summer. The mean concentration of total microbes was 6.55 × 10(5)Cells/m(3) on non-hazy days. The total microbe concentration increased to 7.09 × 10(5) and 9.00 × 10(5)Cells/m(3) on hazy and foggy days, respectively. The particle sizes of the total microbes presented a bimodal distribution on sunny days, with one peak at 1.1-2.1 μm and another at 4.7-7.0 μm. The size distribution of total microbes showed an increase in the fine fraction on hazy days and an increase in the coarse fraction on foggy days. However, the size distribution became unimodal during a heating period. Spearman correlation analysis showed that temperature and O3 had a significant negative correlation with the airborne microbe concentration, while PM2.5, SO2, NO2, CO and the air quality index (AQI) had significant positive correlations with the airborne microbe concentration during hazy days. The increased number of airborne microbes will affect the air quality on hazy days. PMID:26473703

  7. The design and research of distributed cooling type high concentrated photovoltaic module

    NASA Astrophysics Data System (ADS)

    Dai, Mingchong; Yao, Shun; Chen, Bingzhen; Yang, Guanghui; Guo, Limin; Peng, Na; Shen, Du; Bao, Wei; Yang, Cuibai; Zhang, Yang; Wang, Zhiyong

    2015-10-01

    At present, the conversion efficiency of high concentrated photovoltaic modules is about 30%, most of the solar energy is converted into heat, which will result in solar cell temperature rise and subsequent module efficiency decrease. For existing module with large solar cell, the heat source is concentrated and additional cooling fins must be used, resulting in high system complexity and cost rise. In order to lower the cost of photovoltaic, we developed distributed cooling type module with simple structure. This paper depicts a distributed cooling design for high concentrated photovoltaic module, as well as the thermal simulation of this design with analysis software. Module prototype was also made to test the actual effect. The final outdoor results showed high consistency with the simulation results. The chip temperature can be lower than 45° and the module outdoor working efficiency is higher than 26% and lower temperature provide a guarantee of long-term reliability to module packaging material.

  8. Profiling the local carrier concentration and dopant distribution across a semiconductor quantum dot

    NASA Astrophysics Data System (ADS)

    Walrath, J. C.; Chang, A. S.; Lin, Y. H.; Huang, S.; Goldman, R. S.

    We profile the local carrier concentration, n, across epitaxial InAs/GaAs quantum dots (QDs) consisting of 3D islands on top of a 2D alloy layer. We use scanning thermoelectric microscopy to profile the temperature gradient-induced voltage, which is converted to a profile of the local Seebeck coefficient, S. The S profile is then converted to a conduction band-edge profile and compared with Poisson-Schrodinger band-edge simulations. Our combined computational-experimental approach suggests a reduced carrier concentration in the QD center in comparison to that of the 2D alloy layer. We further use 3D atom probe tomography, which enables 3D imaging with a few Angstrom resolution, to profile the distribution of Si dopants. We discuss the correlation between the Si dopant distribution and the observed carrier concentration profile.

  9. Boron nitride nanotubes selectively permeable to cations or anions.

    PubMed

    Hilder, Tamsyn A; Gordon, Daniel; Chung, Shin-Ho

    2009-12-01

    Biological ion channels in membranes are selectively permeable to specific ionic species. They maintain the resting membrane potential, generate propagated action potentials, and control a wide variety of cell functions. Here it is demonstrated theoretically that boron nitride nanotubes have the ability to carry out some of the important functions of biological ion channels. Boron nitride nanotubes with radii of 4.83 and 5.52 A embedded in a silicon nitride membrane are selectively permeable to cations and anions, respectively. They broadly mimic some of the permeation characteristics of gramicidin and chloride channels. Using distributional molecular dynamics, which is a combination of molecular and stochastic dynamics simulations, the properties of these engineered nanotubes are characterized, such as the free energy encountered by charged particles, the water-ion structure within the pore, and the current-voltage and current-concentration profiles. These engineered nanotubes have potential applications as sensitive biosensors, antibiotics, or filtration devices. PMID:19795403

  10. Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements

    NASA Astrophysics Data System (ADS)

    Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be discussed together with meteorological parameters and trace gas measurements. Acknowledgement: PEGASOS project funded by the European Commission and the Framework Program 7 (FP7-ENV-2010-265148).

  11. Fluoride concentrations and distribution in premolars of children from low and optimal fluoride areas.

    PubMed

    Takeuchi, K; Nakagaki, H; Toyama, Y; Kimata, N; Ito, F; Robinson, C; Weatherell, J A; St-osser, L; Künzel, W

    1996-01-01

    We have compared the fluoride (F) concentrations from the enamel surface to the dentino-enamel junction (DEJ), and through dentine to the dentino-pulpal junction (DPJ) in premolars extracted from school children in Chemnitz (former Karl-Marx-Stadt), Germany (F: 1.0 ppm in the water supply), Erfurt, Germany (F: 0.2 ppm in the water supply) and Nagoya, Japan (F: 0.1 ppm in the water supply). In teeth from children in Cheminitz, Erfurt and Nagoya, the profiles of F distribution using an abrasive microsampling technique revealed high F concentrations in the enamel surface, with a substantial decrease towards a plateau in the interior. In dentine the F concentrations were higher than in enamel, and also decreased to a plateau from the DEJ, thereafter increasing considerably towards the DPJ. F concentrations at any depth in the enamel and dentine of teeth from Chemnitz were 2-3 times higher than those in Erfurt and Nagoya. There was no significant difference in F concentrations or distributions between Erfurt and Nagoya. Close to the DEJ in both enamel and dentine as well as the enamel surface and the DPJ side of dentine, higher F concentrations were observed in Chemnitz compared with Erfurt and Nagoya. PMID:8850587

  12. Cadmium distribution in sediment and the lugworm Arenicola marina in a low concentration exposure experiment

    SciTech Connect

    Everaarts, J.M.; SaralaDevi, K.

    1996-12-31

    In the central and southern North Sea, and in the Dutch coastal zone, total cadmium (Cd) concentrations in water are 0.02 {+-} 0.01 {mu}g/L and 0.06 {+-} 0.02 {mu}g/L, respectively Cadmium in the estuarine waters of the Dutch Wadden Sea varied from 0.3 {+-} 0.01 {mu}g/L in the western part to 0.08 {+-} 0.03 {mu}g/L in the eastern part. In whole sediment, the Cd background concentration for the Wadden Sea is 0.5 {+-} 0.01 {mu}g/g dry weight (dw), whereas the reference concentration is 0.08 {+-} 0.02 {mu}g/g dw. The concentrations of total-Cd in surface bulk sediments (0-2 cm) of the central North Sea (Oyster Grounds), and of intertidal mud-flats in the western Wadden Sea varied from 0.05 to 0.15 {mu}g/g dw and from 0.13 to 0.46 {mu}g dw, respectively (calculated from Kahn et al. 1992). These concentration ranges match the reference Cd concentration for Wadden Sea whole sediment (0.5 {+-} 0.01) {mu}g/g dw. Cadmium concentrations in surface sediments of the Dutch coastal zone and estuaries are only slightly elevated compared to the 0.2 {mu}g/g dw, considered as the background concentrations in pristine areas, but well below the level of 10 {mu}g/g dw at heavily contaminated sites. This laboratory study reports on the distribution of cadmium in the sediment column, and the uptake in the blood/coelomic fluid, intestine and body-wall of lugworms at low cadmium concentration exposure. The aim was to determine possible interaction between the vertical distribution of sediment-bound cadmium and the bioturbating activity of lugworms. 14 refs., 3 figs., 2 tabs.

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

    SciTech Connect

    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

    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).

  14. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  15. Effects of microgravity on growth hormone concentration and distribution in plants

    NASA Technical Reports Server (NTRS)

    Schulze, Aga; Jensen, Philip; Desrosiers, Mark; Bandurski, Robert S.

    1989-01-01

    On earth, gravity affects the distribution of the plant growth hormone, indole-3-acetic acid (IAA), in a manner such that the plant grows into a normal vertical orientation (shoots up, roots down). How the plant controls the amount and distribution of IAA is only partially understood and is currently under investigation in this laboratory. The question to be answered in the flight experiment concerns the effect of gravity on the concentration, turn over, and distribution of the growth hormone. The answer to this question will aid in understanding the mechanism by which plants control the amount and distribution of growth hormone. Such knowledge of a plant's hormonal metabolism may aid in the growth of plants in space and will lead to agronomic advances.

  16. Evaluation of regional background particulate matter concentration based on vertical distribution characteristics

    NASA Astrophysics Data System (ADS)

    Han, S.; Zhang, Y.; Wu, J.; Zhang, X.; Tian, Y.; Wang, Y.; Ding, J.; Yan, W.; Bi, X.; Shi, G.; Cai, Z.; Yao, Q.; Huang, H.; Feng, Y.

    2015-10-01

    Heavy regional particulate matter (PM) pollution in China has resulted in an important and urgent need for joint control actions among cities. It is advisable to improve the understanding of the regional background concentration of PM for the development of efficient and effective joint control policies. With the increase of height the influence of source emission on local air quality decreases with altitude, but the characteristics of regional pollution gradually become obvious. A method to estimate regional background PM concentration is proposed in this paper, based on the vertical characteristics of periodic variation in the atmospheric boundary layer structure and particle mass concentration, as well as the vertical distribution of particle size, chemical composition and pollution source apportionment. According to the method, the averaged regional background PM2.5 concentration in July, August and September 2009, being extracted from the original time series in Tianjin, was 40 ± 20, 64 ± 17 and 53 ± 11 μg m-3, respectively.

  17. Emission of submicron aerosol particles in cement kilns: Total concentration and size distribution.

    PubMed

    Rotatori, Mauro; Mosca, Silvia; Guerriero, Ettore; Febo, Antonio; Giusto, Marco; Montagnoli, Mauro; Bianchini, Massimo; Ferrero, Renato

    2015-01-01

    Cement plants are responsible for particle and gaseous emissions into the atmosphere. With respect to particle emission, the greater part of is in the range from 0.05 to 5.0 µm in diameter. In the last years attention was paid to submicron particles, but there is a lack of available data on the emission from stationary sources. In this paper, concentration and size distribution of particles emitted from four cement kilns, in relationship to operational conditions (especially the use of alternative fuel to coal) of the clinker process are reported. Experimental campaigns were carried out by measuring particles concentration and size distribution at the stack of four cement plants through condensation particle counter (CPC) and scanning mobility particle sizer spectrometer (SMPS). Average total particle number concentrations were between 2000 and 4000 particles/cm³, about 8-10 times lower that those found in the corresponding surrounding areas. As for size distribution, for all the investigated plants it is stable with a unimodal distribution (120-150 nm), independent from the fuel used. PMID:25946956

  18. Spectromicroscopy of boron for the optimization of boron neutron capture therapy (BNCT) for cancer

    NASA Astrophysics Data System (ADS)

    Gilbert, B.; Redondo, J.; Baudat, P.-A.; Lorusso, G. F.; Andres, R.; Van Meir, E. G.; Brunet, J.-F.; Hamou, M.-F.; Suda, T.; Mercanti, Delio; Ciotti, M. Teresa; Droubay, T. C.; Tonner, B. P.; Perfetti, P.; Margaritondo, M.; DeStasio, Gelsomina

    1998-10-01

    We used synchrotron spectromicroscopy to study the microscopic distribution of boron in rat brain tumour and healthy tissue in the field of boron neutron capture therapy (BNCT). The success of this experimental cancer therapy depends on the preferential uptake of ? in tumour cells after injection of a boron compound (in our case ?, or BSH). With the Mephisto (microscope à emission de photoélectrons par illumination synchrotronique de type onduleur) spectromicroscope, high-magnification imaging and chemical analysis was performed on brain tissue sections from a rat carrying an implanted brain tumour and the results were compared with inductively coupled plasma-atomic emission spectroscopy (ICP-AES) detection of boron in bulk tissue. Boron was found to have been taken up more favourably by regions of tumour rather than healthy tissue, but the resulting boron distribution in the tumour was inhomogeneous. The results demonstrate that Mephisto can perform microchemical analysis of tissue sections, detect and localize the presence of boron with submicron spatial resolution. The application of this technique to boron in brain tissue can therefore be used to evaluate the current efforts to optimize BNC therapy.

  19. Investigations on boron levels in drinking water sources in China.

    PubMed

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

    2010-06-01

    To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results showed that boron existed in public drinking water sources mainly in dissolved status with total concentrations ranging from 0.003 to 0.337 mg/L (mean = 0.046 mg/L). The mean boron concentrations in mineral and pure bottled water were 0.052 and 0.028 mg/L, respectively. The results obtained in this work showed that there was no health risk on view of boron in public drinking water sources and bottled water. In boron industrial area, boron concentrations in surface water and ground water were 1.28 mg/L (range = 0.007-3.8 mg/L) and 18.3 mg/L (range = 0.015-140 mg/L), respectively, which indicated that boron industry caused boron pollution in local water system. PMID:19444639

  20. Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.

    PubMed

    Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

    2014-09-01

    The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibility<2km) and moderate (2km≤visibility<3km) haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm(3) in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1μm and 1-10μm size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100nm and 100-200nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15μm(3)/cm(3) and 949, 649, 206μm(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1μm increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. PMID:25193840

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

    NASA Astrophysics Data System (ADS)

    Kubala-Kukuś, A.; Banaś, D.; Braziewicz, J.; Góźdź, S.; Majewska, U.; Pajek, M.

    2007-07-01

    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.

  2. Estimation of pore size distribution using concentric double pulsed-field gradient NMR.

    PubMed

    Benjamini, Dan; Nevo, Uri

    2013-05-01

    Estimation of pore size distribution of well calibrated phantoms using NMR is demonstrated here for the first time. Porous materials are a central constituent in fields as diverse as biology, geology, and oil drilling. Noninvasive characterization of monodisperse porous samples using conventional pulsed-field gradient (PFG) NMR is a well-established method. However, estimation of pore size distribution of heterogeneous polydisperse systems, which comprise most of the materials found in nature, remains extremely challenging. Concentric double pulsed-field gradient (CDPFG) is a 2-D technique where both q (the amplitude of the diffusion gradient) and φ (the relative angle between the gradient pairs) are varied. A recent prediction indicates this method should produce a more accurate and robust estimation of pore size distribution than its conventional 1-D versions. Five well defined size distribution phantoms, consisting of 1-5 different pore sizes in the range of 5-25 μm were used. The estimated pore size distributions were all in good agreement with the known theoretical size distributions, and were obtained without any a priori assumption on the size distribution model. These findings support that in addition to its theoretical benefits, the CDPFG method is experimentally reliable. Furthermore, by adding the angle parameter, sensitivity to small compartment sizes is increased without the use of strong gradients, thus making CDPFG safe for biological applications. PMID:23548563

  3. Ni doping of semiconducting boron carbide

    SciTech Connect

    Hong, Nina; Liu Jing; Adenwalla, S.; Langell, M. A.; Kizilkaya, Orhan

    2010-01-15

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

  4. Boron strengthening in FeAl

    SciTech Connect

    Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.

    1998-11-01

    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.

  5. Inducibility of human atrial fibrillation in an in silico model reflecting local acetylcholine distribution and concentration

    PubMed Central

    Hwang, Minki; Lee, Hyun-Seung

    2016-01-01

    Vagal nerve activity has been known to play a crucial role in the induction and maintenance of atrial fibrillation (AF). However, it is unclear how the distribution and concentration of local acetylcholine (ACh) promotes AF. In this study, we investigated the effect of the spatial distribution and concentration of ACh on fibrillation patterns in an in silico human atrial model. A human atrial action potential model with an ACh-dependent K+ current (IKAch) was used to examine the effect of vagal activation. A simulation of cardiac wave dynamics was performed in a realistic 3D model of the atrium. A model of the ganglionated plexus (GP) and nerve was developed based on the "octopus hypothesis". The pattern of cardiac wave dynamics was examined by applying vagal activation to the GP areas or randomly. AF inducibility in the octopus hypothesis-based GP and nerve model was tested. The effect of the ACh concentration level was also examined. In the single cell simulation, an increase in the ACh concentration shortened APD90 and increased the maximal slope of the restitution curve. In the 3D simulation, a random distribution of vagal activation promoted wavebreaks while ACh secretion limited to the GP areas did not induce a noticeable change in wave dynamics. The octopus hypothesis-based model of the GP and nerve exhibited AF inducibility at higher ACh concentrations. In conclusion, a 3D in silico model of the GP and parasympathetic nerve based on the octopus model exhibited higher AF inducibility with higher ACh concentrations. PMID:26807030

  6. Inducibility of human atrial fibrillation in an in silico model reflecting local acetylcholine distribution and concentration.

    PubMed

    Hwang, Minki; Lee, Hyun-Seung; Pak, Hui-Nam; Shim, Eun Bo

    2016-01-01

    Vagal nerve activity has been known to play a crucial role in the induction and maintenance of atrial fibrillation (AF). However, it is unclear how the distribution and concentration of local acetylcholine (ACh) promotes AF. In this study, we investigated the effect of the spatial distribution and concentration of ACh on fibrillation patterns in an in silico human atrial model. A human atrial action potential model with an ACh-dependent K(+) current (IKAch) was used to examine the effect of vagal activation. A simulation of cardiac wave dynamics was performed in a realistic 3D model of the atrium. A model of the ganglionated plexus (GP) and nerve was developed based on the "octopus hypothesis". The pattern of cardiac wave dynamics was examined by applying vagal activation to the GP areas or randomly. AF inducibility in the octopus hypothesis-based GP and nerve model was tested. The effect of the ACh concentration level was also examined. In the single cell simulation, an increase in the ACh concentration shortened APD90 and increased the maximal slope of the restitution curve. In the 3D simulation, a random distribution of vagal activation promoted wavebreaks while ACh secretion limited to the GP areas did not induce a noticeable change in wave dynamics. The octopus hypothesis-based model of the GP and nerve exhibited AF inducibility at higher ACh concentrations. In conclusion, a 3D in silico model of the GP and parasympathetic nerve based on the octopus model exhibited higher AF inducibility with higher ACh concentrations. PMID:26807030

  7. Influence of dissolved-air concentration on spatial distribution of bubbles for sonochemistry.

    PubMed

    Tuziuti, Toru; Yasui, Kyuichi; Sivakumar, Manickam; Iida, Yasuo

    2006-12-22

    The pulsation of ultrasonic cavitation bubbles at various dissolved-air concentration in a sonochemical reaction field of standing-wave type is investigated experimentally by laser-light scattering. When a thin light sheet, finer than half the wavelength of sound, is introduced into the cavitation bubbles at an antinode of sound pressure, the scattered light intensity oscillates. The peak-to-trough light intensity is correlated with the number of bubbles that contribute to the sonochemical reaction. It is shown that as the dissolved air concentration becomes higher, the weighted center of the spatial distribution of the peak-to-trough intensity tends to shift towards the liquid surface. At higher concentration of the dissolved air, a great deal of bubbles with size distribution generated due to coalescence between bubbles disturbs sound propagation to change the sound phase easily. A standing wave to trap tiny oscillating bubbles is established only at the side which is nearer to the liquid surface. Also at higher concentration, liquid flow induced by drag motion of bubbles by the action of radiation force becomes apparent and position-unstable region of bubble is enlarged from the side of sound source towards the liquid surface. Therefore, the position of oscillating bubbles active for sonochemical reaction is limited at the side which is nearer to the liquid surface at higher concentration of the dissolved air. PMID:16780909

  8. Liver iron concentration and distribution in chronic hepatitis C before and after interferon treatment.

    PubMed Central

    Boucher, E; Bourienne, A; Adams, P; Turlin, B; Brissot, P; Deugnier, Y

    1997-01-01

    BACKGROUND: Recent studies have suggested that, in patients with chronic hepatitis C, elevated iron stores are predictive of a poor response to interferon. AIMS: To assess liver iron concentration and distribution before and after interferon treatment in patients with hepatitis C in order to evaluate further the role of iron in the pathogenesis of hepatitis C. PATIENTS: Fifty-five patients with hepatitis C treated with alpha interferon for six months. METHODS: Patients were evaluated for liver iron concentration (normal value < 36 mumol/g), and liver iron distribution before and six months after therapy. RESULTS: At entry: liver iron concentration was elevated in 16/55 patients (29%); iron staining (Perls' staining) was found in 31/55 patients (56%) mainly within Kupffer and endothelial cells. Iron load was significantly higher in patients with the most histological inflammatory activity. Following treatment: liver iron concentration decreased significantly (40 (24) to 30 (17) mumol/g, p = 0.001); this was related to iron depletion in mesenchymal cells. Iron depletion occurred regardless of the response to therapy. Elevated liver iron concentration was not found to be a predictive factor of failure of interferon. CONCLUSION: Although liver iron stores were usually normal or only slightly elevated in patients with chronic hepatitis C, biochemical and histological liver iron content decreased following treatment due to the diminution in mesenchymal iron deposits. Iron depletion was interpreted as both a consequence of the anti-inflammatory effect of treatment and a factor of improvement in liver histology. Images PMID:9274482

  9. Direct measurement of concentration distribution within the boundary layer of an ion-exchange membrane.

    PubMed

    Choi, Jae-Hwan; Park, Jin-Soo; Moon, Seung-Hyeon

    2002-07-15

    In this study the concentration distributions within the diffusion boundary layer were obtained by directly measuring the potential drops while the currents (under- and overlimiting) passed through the Neosepta CMX cation-exchange membrane (Tokuyama Corp., Japan). Potential drops according to the distance from the membrane surface on the depleted side were measured using a microelectrode to obtain the concentration profile. From the concentration profiles obtained, it was observed that the diffusion boundary layers existed in the range of 300-350 microm, which reasonably coincide with the theoretical diffusion boundary layer thickness calculated from the limiting current density. Although there were some deviations between the concentrations determined from the Nernst model and those from experiments, it was confirmed that the Nernst model effectively depicts the transport phenomena in the ion-exchange membrane system. In addition it was found that the salt concentration at the membrane surface increased when the currents applied exceeded the limiting current. It is thought that the concentration polarization formed in the diffusion boundary layer at currents near or lower than the limiting current was disturbed by a turbulent convection when the current was greater than the limiting current. As a consequence, the concentration at the membrane surface increased to a sufficient level for generation of the overlimiting current. PMID:16290735

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

    PubMed

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

    2011-07-01

    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

  11. Axial channeling of boron ions into silicon

    NASA Astrophysics Data System (ADS)

    La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carbera, A.; Gasparotto, A.

    1992-04-01

    Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5 × 10 11 and 1 × 10 15 atoms/cm 2. The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, Sc, was extracted from the experimental maximum ranges for the [100] and [110] axis. The energ dependence of the electronic stopping power is given by Sc = KEp with p[100] = 0.469±0.010 and p[110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles.

  12. Characterization of background concentrations of contaminants using a mixture of normal distributions.

    PubMed

    Qian, Song S; Lyons, Regan E

    2006-10-01

    We present a Bayesian approach for characterizing background contaminant concentration distributions using data from sites that may have been contaminated. Our method, focused on estimation, resolves several technical problems of the existing methods sanctioned by the U.S. Environmental Protection Agency (USEPA) (a hypothesis testing based method), resulting in a simple and quick procedure for estimating background contaminant concentrations. The proposed Bayesian method is applied to two data sets from a federal facility regulated under the Resource Conservation and Restoration Act. The results are compared to background distributions identified using existing methods recommended by the USEPA. The two data sets represent low and moderate levels of censorship in the data. Although an unbiased estimator is elusive, we show that the proposed Bayesian estimation method will have a smaller bias than the EPA recommended method. PMID:17051794

  13. Boron nitride converted carbon fiber

    DOEpatents

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

    2016-04-05

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

  14. Spatially Resolved Temperature and Water Vapor Concentration Distributions in Supersonic Combustion Facilities by TDLAT

    NASA Technical Reports Server (NTRS)

    Busa, K. M.; McDaniel J. C.; Diskin, G. S.; DePiro, M. J.; Capriotti, D. P.; Gaffney, R. L.

    2012-01-01

    Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. More than 2500 separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Due to the UVaSCF s unique electrical heating and ability for vitiate addition, measurements collected at the UVaSCF are presented as a calibration of the technique. Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Tomographic temperature and water vapor concentration distributions are presented from experimentation on the UVaSCF operating at a high temperature non-reacting case for water vitiation level of 12%. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are also presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters.

  15. On the concentration of large deviations for fat tailed distributions, with application to financial data

    NASA Astrophysics Data System (ADS)

    Filiasi, Mario; Livan, Giacomo; Marsili, Matteo; Peressi, Maria; Vesselli, Erik; Zarinelli, Elia

    2014-09-01

    Large deviations for fat tailed distributions, i.e. those that decay slower than exponential, are not only relatively likely, but they also occur in a rather peculiar way where a finite fraction of the whole sample deviation is concentrated on a single variable. The regime of large deviations is separated from the regime of typical fluctuations by a phase transition where the symmetry between the points in the sample is spontaneously broken. For stochastic processes with a fat tailed microscopic noise, this implies that, while typical realizations are well described by a diffusion process with continuous sample paths, large deviation paths are typically discontinuous. For eigenvalues of random matrices with fat tailed distributed elements, a large deviation where the trace of the matrix is anomalously large concentrates on just a single eigenvalue, whereas in the thin tailed world the large deviation affects the whole distribution. These results find a natural application to finance. Since the price dynamics of financial stocks are characterized by fat tailed increments, large fluctuations in stock prices are expected to be realized by discrete jumps. Interestingly, we find that large excursions of prices are more likely realized by continuous drifts rather than by discontinuous jumps. Indeed, auto correlations suppress the concentration of large deviations. Financial covariance matrices also exhibit an anomalously large eigenvalue, the market mode, as compared to the prediction of random matrix theory. We show that this is explained by a large deviation with excess covariance rather than by one with excess volatility.

  16. The association between spatial distribution of common malignancies and soil lead concentration in Isfahan, Iran

    PubMed Central

    Rashidi, Masoumeh; Rameshat, Mohammad Hossein; Gharib, Hadi; Rouzbahani, Reza; Ghias, Majid; Poursafa, Parinaz

    2012-01-01

    Background: Malignancies are primarily environmental diseases mostly attributed to environmental factors. By plotting the prevalence and spatial distribution maps, important differences can be observed in detail. This study aimed to determine the association between map distribution of malignancies and the geological phenomena of lead (Pb) accumulation in soil in the province of Isfahan, Iran. Methods: Spatial distribution maps of malignant diseases were plotted by using data recorded during 2007 to 2009 in the Isfahan Cancer Registry Program. Data on Pb accumulation in soil was obtained from the National Geological Survey and Mineral Exploration. Pb concentrations were documented in three parts of agricultural, non-agricultural, urban, and industrial land. The geographical mapping of cancers and soil Pb were then incorporated into a geographic information system (GIS) to create a spatial distribution model. Results: The spatial distributions of ten common malignant diseases in the province, i.e. skin cancers, hematological malignancies, and breast cancers, followed by other malignancies were scattered based on Pb distribution. In fact, common cancers were more prevalent in the parts of the province where soil Pb was more abundant. Conclusion: The findings of this study underscore the importance of preventing Pb exposure and controlling industrial production of Pb. The data is also important to establish further effects modeling for cancers. Moreover, physicians and health professionals should consider the impact of environmental factors on their patients’ health. PMID:23267396

  17. Model of boron diffusion from gas phase in silicon carbide

    SciTech Connect

    Aleksandrov, O. V.; Mokhov, E. N.

    2011-06-15

    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.

  18. 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...

  19. Effect of boron in Fe 70 Al 30 nanostructured alloys produced by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Rico, M. M.; Pérez Alcázar, G. A.; Greneche, J. M.

    2013-04-01

    The substitution of aluminum by boron in the Fe70Al30 system prepared by high energy ball milling is studied when the B content ranged from 0 up to 20 at. %, and the milling times were 24, 48 and 72 h. X-ray diffraction (XRD) patterns of Fe70Al30 showed a predominant bcc structural phase with a lattice parameter larger than that of α-Fe. A second (tetragonal) phase arose with the addition of boron. It is associated to the existence of (Fe, Al)2B, although the values of the lattice parameters are slightly different from those found in the literature. This phase shows high stability; its lattice parameters and the Mössbauer parameters do not show notable variations, either with milling time or composition. It was also evidenced that an increase of boron content and of milling time produced a decrease of the lattice parameter of the Fe-Al bcc structure. This is in agreement with the small atomic radius of boron in comparison with that of aluminum. This also allows boron to occupy interstitial sites in the lattice, increasing the grain size and giving rise to the ductile character of the alloy. On the other hand, 300 K transmission Mössbauer spectra (TMS) were fitted, for low boron concentrations (<8 at.%), with a hyperfine field distribution (HFD) associated with the bcc phase. For high boron content (≥8 at.%), a magnetic component related to the tetragonal phase is added and its broadened lines are attributed to the disordered character of Fe2B, probably induced by the milling process.

  20. Effect of boron in Fe 70 Al 30 nanostructured alloys produced by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Rico, M. M.; Pérez Alcázar, G. A.; Greneche, J. M.

    2014-01-01

    The substitution of aluminum by boron in the Fe70Al30 system prepared by high energy ball milling is studied when the B content ranged from 0 up to 20 at. %, and the milling times were 24, 48 and 72 h. X-ray diffraction (XRD) patterns of Fe70Al30 showed a predominant bcc structural phase with a lattice parameter larger than that of α-Fe. A second (tetragonal) phase arose with the addition of boron. It is associated to the existence of (Fe, Al)2B, although the values of the lattice parameters are slightly different from those found in the literature. This phase shows high stability; its lattice parameters and the Mössbauer parameters do not show notable variations, either with milling time or composition. It was also evidenced that an increase of boron content and of milling time produced a decrease of the lattice parameter of the Fe-Al bcc structure. This is in agreement with the small atomic radius of boron in comparison with that of aluminum. This also allows boron to occupy interstitial sites in the lattice, increasing the grain size and giving rise to the ductile character of the alloy. On the other hand, 300 K transmission Mössbauer spectra (TMS) were fitted, for low boron concentrations (<8 at.%), with a hyperfine field distribution (HFD) associated with the bcc phase. For high boron content (≥8 at.%), a magnetic component related to the tetragonal phase is added and its broadened lines are attributed to the disordered character of Fe2B, probably induced by the milling process.

  1. A new algorithm and its application about distributed snowmelt concentration model

    NASA Astrophysics Data System (ADS)

    Liu, Yongqiang; Dai, Wei; Fang, Shifeng; Liu, Zhihui

    2009-10-01

    Based on "3S" (RS, GIS, GPS) technologies and completely distributed design ideas, a new algorithm of the Distributed Snowmelt Concentration Model is designed and built after study the Distributed Snowmelt Runoff Model. It has spatiotemporal features and takes the DEM data, which with high resolution, as a foundation and picks up the hydrological factors, such as slope, gradient, direction of flow, collecting time, drainage network etc., and the algorithm is simple to understand and to implement, requiring only a few tens of code lines and running faster. So the algorithm will be versatile. Meanwhile, a new conception "Period Unit of Time-step" is put forward in this paper, and the algorithm procedure is fully detailed too. After the model applied in the representative study area, Juntanghu Basin, which located in the North-Tianshan Mountains, China, and contrasted with the homologous observed data obtained in the same field, the simulation results show clearly that the Distributed Snowmelt Concentration Model and its algorithm is very good.

  2. Boron-Loaded Silicone Rubber Scintillators

    SciTech Connect

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

    2003-05-12

    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.

  3. [Concentration and size distribution of bioaerosols at non-haze and haze days in Beijing].

    PubMed

    Gao, Min; Qiu, Tian-lei; Jia, Rui-zhi; Han, Mei-lin; Song, Yuan; Wang, Xu-ming

    2014-12-01

    In recent years, haze has been observed frequently in Beijing. Haze was one of the atmospheric phenomena caused by the accumulation of particulate matter. As an important fraction of particular matter, bioaerosol could potentially cause significantly negative health effects. In this study, we detected the concentration and size distribution of viable bioaerosol during non-haze and haze days, analyzed correlation of viable bioaerosol with the ambient temperature and relative humidity using Spearman's correlation coefficient and finally detected the changing of size distribution of viable bioaerosol in summer and winter. Results indicated that concentrations of viable bioaerosol exhibited a negative correlation with Air Quality Index (AQI) of PM2.5 and positive correlation with temperature. Relative humidity had a negative correlation with airborne bacteria while positive correlation with airborne fungi. The highest concentration of airborne bacteria and fungi were detected at size arrange of 4.5-7.0 ?m and 2. 1-3.3 ?m in the winter, respectively. In the summer, both the highest concentration of airborne bacteria and fungi were observed at size arrange of 3.3-4.5 ?m. The results of this study will provide the basis data for hazard evaluation of bioaerosol on human health at non-haze and haze days. PMID:25826908

  4. Visualization of the concentration distribution of Asian dust in the Google Earth

    NASA Astrophysics Data System (ADS)

    Kusaka, Takashi; Kono, Takafumi; Okuda, Wataru; Nakano, Yu

    2010-11-01

    A method for identifying the released region of Asian dust using the wind velocity near the surface and the long-range inverse transport model that traces the wind field in the backward direction from positions where Asian dust was observed is described. The spatio-temporal concentration distribution of dust clouds over the East Asia was computed in the case that Asian dust clouds were observed in Japan from April 1 to April 2, 2007. In this case, the released mass flux of Asian dust in source regions was determined such that the simulated concentration of Asian dust almost corresponds to the concentration of the suspended particulate matter (SPM) measured at various places in Japan. In order to better understand through which paths sand dust particles are transported to Japan, the time variation of the concentration distribution of Asian dust clouds and the wind field at 950hPa from 22:00 on March 30 to 15:00 on April 4, 2007was animated every one hour in the Google Earth.

  5. Vertical distribution of (137)Cs activity concentration in marine sediments at Amvrakikos Gulf, western of Greece.

    PubMed

    Tsabaris, C; Patiris, D L; Fillis-Tsirakis, E; Kapsimalis, V; Pilakouta, M; Pappa, F K; Vlastou, R

    2015-06-01

    The aim of the present work is the study of (137)Cs migration in sediment column taking into account the sedimentation rate in the Amvrakikos Gulf, at the western part of Greece. Marine core sediments were collected and the measurements were performed using the high resolution gamma-ray spectrometry method. The vertical distribution of (137)Cs activity concentration, as part of anthropogenic marine radioactivity, provided averaged sedimentation rate by identifying the depths of activity concentrations due to the Chernobyl accident and the nuclear tests signals. Furthermore, (137)Cs measurements were reproduced using the proposed one-dimensional diffusion-advection model which provides mainly as an output, the sedimentation rate and the average diffusivity of (137)Cs in the sediment column. The proposed model estimates the temporal variation of (137)Cs activity concentration from 1987 (one year after the Chernobyl accident) till today (2014). PMID:25771157

  6. Simultaneous Observation of Cells and Nuclear Tracks from the Boron Neutron Capture Reaction by UV-C Sensitization of Polycarbonate.

    PubMed

    Portu, Agustina; Rossini, Andrés Eugenio; Thorp, Silvia Inés; Curotto, Paula; Pozzi, Emiliano César Cayetano; Granell, Pablo; Golmar, Federico; Cabrini, Rómulo Luis; Martin, Gisela Saint

    2015-08-01

    The distribution of boron in tissue samples coming from boron neutron capture therapy protocols can be determined through the analysis of its autoradiography image on a nuclear track detector. A more precise knowledge of boron atom location on the microscopic scale can be attained by the observation of nuclear tracks superimposed on the sample image on the detector. A method to produce an "imprint" of cells cultivated on a polycarbonate detector was developed, based on the photodegradation properties of UV-C radiation on this material. Optimal conditions to generate an appropriate monolayer of Mel-J cells incubated with boronophenylalanine were found. The best images of both cells and nuclear tracks were obtained for a neutron fluence of 1013 cm-2, 6 h UV-C (254 nm) exposure, and 4 min etching time with a KOH solution. The imprint morphology was analyzed by both light and scanning electron microscopy. Similar samples, exposed to UV-A (360 nm) revealed no cellular imprinting. Etch pits were present only inside the cell imprints, indicating a preferential boron uptake (about threefold the incubation concentration). Comparative studies of boron absorption in different cell lines and in vitro evaluation of the effect of diverse boron compounds are feasible with this methodology. PMID:26155721

  7. The interaction of boron with goethite: experiments and CD-MUSIC modeling.

    PubMed

    Goli, Esmaiel; Rahnemaie, Rasoul; Hiemstra, Tjisse; Malakouti, Mohammad Jafar

    2011-03-01

    Boron (B) is an essential element for plants and animals growth that interacts with mineral surfaces regulating its bioavailability and mobility in soils, sediments, and natural ecosystems. The interaction with mineral surfaces is quite important because of a narrow range between boron deficiency and toxicity limits. In this study, the interaction of boric acid with goethite (α-FeOOH) was measured in NaNO(3) background solution as a function of pH, ionic strength, goethite and boron concentration representing as adsorption edges and isotherms. Boron adsorption edges showed a bell-shaped pattern with maximum adsorption around pH 8.50, whereas adsorption isotherms were rather linear. The adsorption data were successfully described with the CD-MUSIC model in combination with the Extended Stern (ES) model. The charge distribution (CD) of inner-sphere boron surface complexes was calculated from the geometry optimized with molecular orbital calculations applying density functional theory (MO/DFT). The CD modeling suggested dominant binding of boric acid as a trigonal inner-sphere complex with minor contributions of a tetrahedral inner-sphere complex (at high pH) and a trigonal outer-sphere complex (at low pH). The interpretation with the CD model is consistent with the spectroscopic observations. PMID:21185584

  8. Boron carbides from first principles

    NASA Astrophysics Data System (ADS)

    Vast, Nathalie; Sjakste, Jelena; Betranhandy, Emmanuel

    2009-06-01

    In this work, we focus on the understanding gained from the investigation of the physical properties of boron carbides with theoretical methods based on density functional theory (DFT). Together with the examination of the DFT total energies of various atomic configurations in the unit cell, comparison with the experiments of the theoretical vibrational or NMR spectra has led to the determination of the atomic structure of B4C as C-B-C chains linking mostly B11C icosahedra, and a few percents of B10C2 icosahedra. In the icosahedron, the carbon atom is found to be in the polar site (B4Cp). When there are two carbon atoms, they are found to be in antipodal polar positions. At carbon concentrations other than 20%, we find that only four structural models have a negative formation energy with respect to a formation from α-boron + diamond. Moreover, they all have a positive formation energy with respect to B4Cp, showing a tendency to decompose into B4Cp + α-boron or B4Cp + diamond. This metastability explains actual difficulties in the synthesis of clean samples, in particular for B13C2. Finally, the idea of combining high hardness and superconductivity in the same material by doping boron-rich solids has emerged. We show results on the strength of the electron-phonon coupling constant obtained with DFT-based methods in B13C2.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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. Collocated with the Lidar system we deployed an extractive system inclusive of a LiCor 840 to monitor CO2 concentrations, a laser aerosol spectrometer to measure particle size distributions for PM with diameter larger than 0.1 µm, and a portable condensation particle counter to estimate the total particle number concentration for particles with diameters between~30nm and 1 µm. In addition, road-side vehicle exhaust particles were collected on nuclepore filters for scanning electron microscopy analysis during selected periods of time. In this study we analyze fuel-based mass and number PM emission factors from passing vehicles. The emission factors are estimated normalizing the PM data by the CO2 concentration. The morphology of the particulates is also investigated with electron microscopy analysis. Type of vehicles and traffic counts were recorded by one of the researchers during the sampling period to evaluate the influence on particle morphology due to traffic volume and fuel type. Image processing and fractal geometry are used to estimate various morphological parameters and fractal dimension. Diurnal variation of particle morphology descriptors and fractal dimension of soot particles are investigated and compared with CO2 emissions, particle size distribution and particle number concentration for selected subsets of the data. Variations of PM emission factors and PM morphology are also investigated for different traffic conditions and days of the week. The analysis of the PM data is of particular importance in monitoring vehicle emissions and in designing emission reduction strategies to improve air quality and public health.

  10. [Temporal and spatial distribution of ozone concentration by aircraft sounding over Beijing].

    PubMed

    Chen, Peng-Fei; Zhang, Qiang; Quan, Jian-Nong; Gao, Yang; Huang, Meng-Yu

    2012-12-01

    Based on the aircraft sounding volume fraction concentration data of ozone (O3), nitrogen oxides (NO, NO2) and other data in Beijing from 2007 to 2010, temporal and spatial evolution of ozone concentration from the ground surface to 3.5 km altitude were studied. Results show that: (1) Vertical profiles of monthly average O3 concentration were in good agreement, with increasing altitude, the concentrations were first increased and then decreased, and then remained almost constant, and there was a clear dividing line at 1.5 km altitude, the vertical gradient of the O3 concentration changed greatly below which, there were O3 high-value areas, which were influenced by human activities near the ground; the change of vertical gradient of O3 concentration was significantly reduced above 1.5 km altitude, this space was above the mixing layer, where the air mass movement was less affected by underlying surface, and the advection-diffusion played a crucial role in the local accumulation process of air pollutants. (2) Changes of O3 concentration showed clear seasonal characteristics, O3 concentration was lower in spring and autumn, but higher in summer. In the months studied, no significant difference in monthly average O3 concentration from July to September was detected (P > 0.05), but there was significant difference in other months (P < 0.01). (3) In summer days (daytime), the variations in the vertical profiles of hourly O3 concentration were consistent with those of the monthly O3 concentration. The O3 concentration was lower near the surface within 1.5 km in the morning (09:00-10:00), and higher in the afternoon (15:00-16:00), with the maximum discrepancy of about 60 x 10(-9) in the same altitude; there was minor difference in O3 concentration in altitude range of 1.5-3.5 km, generally fluctuating among 70 x 10(-9) -80 x 10(-9). (4) For the regional distribution of O3 concentration, higher concentration within 0-2 km appeared near the Fourth Ring Road of city center and the surrounding areas, the main reasons for this distribution might be the presence of many strong sources of pollution emissions and low sink flow near the ground; within 2-4 km, in addition to the urban area of Beijing, higher O3 concentration areas were found in the north, the south-east (Beijing-Tianjin direction), the south-west (Beijing-Baoding direction). (5) There were significant correlation between O3 and NO, NO2 and NO2/NO within 0-3.5 km, O3 was negatively related with both NO and NO2, but positively correlated with the NO2/NO ratio. PMID:23379135

  11. Pollen Morphology and Boron Concentration in Floral Tissues as Factors Triggering Natural and GA-Induced Parthenocarpic Fruit Development in Grapevine

    PubMed Central

    Pérez-Díaz, Ricardo; Yáñez, Mónica; Tapia, Jaime; Moreno, Yerko

    2015-01-01

    Parthenocarpic fruit development (PFD) reduces fruit yield and quality in grapevine. Parthenocarpic seedless berries arise from fruit set without effective fertilization due to defective pollen germination. PFD has been associated to micronutrient deficiency but the relation of this phenomenon with pollen polymorphism has not been reported before. In this work, six grapevine cultivars with different tendency for PFD and grown under micronutrient-sufficient conditions were analyzed to determine pollen structure and germination capability as well as PFD rates. Wide variation in non-germinative abnormal pollen was detected either among cultivars as well as for the same cultivar in different growing seasons. A straight correlation with PFD rates was found (R2 = 0.9896), suggesting that natural parthenocarpy is related to defective pollen development. Such relation was not observed when PFD was analyzed in grapevine plants exposed to exogenous gibberellin (GA) or abscissic acid (ABA) applications at pre-anthesis. Increase (GA treatment) or reduction (ABA treatment) in PFD rates without significative changes in abnormal pollen was determined. Although these plants were maintained at sufficient boron (B) condition, a down-regulation of the floral genes VvBOR3 and VvBOR4 together with a reduction of floral B content in GA-treated plants was established. These results suggest that impairment in B mobility to reproductive tissues and restriction of pollen tube growth could be involved in the GA-induced parthenocarpy. PMID:26440413

  12. Pollen Morphology and Boron Concentration in Floral Tissues as Factors Triggering Natural and GA-Induced Parthenocarpic Fruit Development in Grapevine.

    PubMed

    Alva, Orlando; Roa-Roco, Rosa Nair; Pérez-Díaz, Ricardo; Yáñez, Mónica; Tapia, Jaime; Moreno, Yerko; Ruiz-Lara, Simón; González, Enrique

    2015-01-01

    Parthenocarpic fruit development (PFD) reduces fruit yield and quality in grapevine. Parthenocarpic seedless berries arise from fruit set without effective fertilization due to defective pollen germination. PFD has been associated to micronutrient deficiency but the relation of this phenomenon with pollen polymorphism has not been reported before. In this work, six grapevine cultivars with different tendency for PFD and grown under micronutrient-sufficient conditions were analyzed to determine pollen structure and germination capability as well as PFD rates. Wide variation in non-germinative abnormal pollen was detected either among cultivars as well as for the same cultivar in different growing seasons. A straight correlation with PFD rates was found (R2 = 0.9896), suggesting that natural parthenocarpy is related to defective pollen development. Such relation was not observed when PFD was analyzed in grapevine plants exposed to exogenous gibberellin (GA) or abscissic acid (ABA) applications at pre-anthesis. Increase (GA treatment) or reduction (ABA treatment) in PFD rates without significative changes in abnormal pollen was determined. Although these plants were maintained at sufficient boron (B) condition, a down-regulation of the floral genes VvBOR3 and VvBOR4 together with a reduction of floral B content in GA-treated plants was established. These results suggest that impairment in B mobility to reproductive tissues and restriction of pollen tube growth could be involved in the GA-induced parthenocarpy. PMID:26440413

  13. Ultralow Contact Resistivity for a Metal/p-Type Silicon Interface by High-Concentration Germanium and Boron Doping Combined with Low-Temperature Annealing

    NASA Astrophysics Data System (ADS)

    Murakoshi, Atsushi; Iwase, Masao; Niiyama, Hiromi; Koike, Mitsuo; Suguro, Kyoichi

    2013-07-01

    A contact resistivity of 6.9×10-9 Ω.cm2 has been obtained in an AlSi (1 wt %)-Cu (0.5 wt %) alloy/silicon system by using heavy-dose ion implantations of germanium and boron combined with low-temperature annealing. The analysis of the combined state showed that B12 cluster was incorporated and the supersaturation activation layer was formed into the region where germanium separated. Separated germanium is expected to have high interface state density. It is considered that this interface state density also has a Fermi level, and in order to reduce the difference from the Fermi level of the substrate, the charge moves to interface state density from the substrate. As a result, it is not based on a metallic material but a work function becomes small because pinning by which a Fermi level is fixed to interface state density occurs owing to the substrate/metal interface. It is considered to be attributable to the existence of a Ge-rich layer formed by low-temperature annealing, and a supersaturation activation layer that lowers contact resistance was formed.

  14. Distribution of sulfhydryl boranes in mice and rats

    SciTech Connect

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

    1986-01-01

    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.

  15. A Study of the Effect of Adhesive and Matrix Stiffnesses on the Axial, Normal, and Shear Stress Distributions of a Boron-epoxy Reinforced Composite Joint. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Howell, W. E.

    1974-01-01

    The mechanical properties of a symmetrical, eight-step, titanium-boron-epoxy joint are discussed. A study of the effect of adhesive and matrix stiffnesses on the axial, normal, and shear stress distributions was made using the finite element method. The NASA Structural Analysis Program (NASTRAN) was used for the analysis. The elastic modulus of the adhesive was varied from 345 MPa to 3100 MPa with the nominal value of 1030 MPa as a standard. The nominal values were used to analyze the stability of the joint. The elastic moduli were varied to determine their effect on the stresses in the joint.

  16. Diffusion-induced dislocations in highly boron-doped silicon layers used for bulk micromachining applications

    NASA Astrophysics Data System (ADS)

    Gaiseanu, Florin; Esteve, Jaume; Kissinger, Gudrun; Kruger, D.

    1998-08-01

    Boron-doped silicon layers with sufficiently high doping levels become effective stop-layers during the chemical etching of silicon in alkaline type solutions (KOH, NaOH, LiOH) or in EDP (ethylene-diamine-pyrocatechol). An advantageous chemical solution consisting in tetramethyl ammonium hydroxide (TMAH) with isopropyl alcohol (IPA), showing similar etching properties was also proposed. The property as a stop layer of the boron-doped silicon is currently used as the most convenient etch-stop technique, because it is easy to define the thickness of the structure by the depth of boron diffusion in silicon. However, the boron diffusion profile in silicon is not a step-like distribution, but it presents a continuous decrease of the concentration from the silicon surface to the bulk, that depending on the diffusion conditions, i.e. diffusion time, temperature and doping technique. It is therefore expected that such a decrease will result to a continuous variation of the etching rate and a consequently variation of the etching time with the diffusion depth. In this paper we present firstly the doping properties of the silicon layers doped by the termo-chemical method using chemical sources. It is shown that the doping properties vary within the boron-doped layers. Boron diffusion profiles determined by SIMS method and electrical method are presented in order show the specific behavior of the concentration distribution in the silicon bulk. Misfit dislocations are induced by the boron diffusion in silicon at high concentrations. The conditions of the generation of the misfit dislocations in the boron-doped layers depends on the processing conditions, especially on the diffusion time and temperature. We show that the density distribution of the misfit dislocations in the silicon bulk is not uniform after the boron prediffusion and diffusion processes. From the point of view of the micromechanical applications, the inhomogeneity of the structural and doping properties of the silicon layer can influence the stress properties of such silicon-doped layers. Therefore, in order to reduce the stress gradient in the silicon membranes and micromechanical elements, it is necessary to obtain layers with uniform material properties. Both the doping and structural properties of the boron doped layers are to be therefore better knowledged and controlled. However, the doping properties obtained after the boron doping by termo-chemical method or by implantation doping technique cannot provide uniformly doped silicon layers. Therefore, a careful chemical etching during the self-limitation process of the boron-doped silicon layers offers such a possibility, as it will be presented in the paper. In order to eliminate from the silicon doped layers the regions were the properties of the silicon layers are not uniform, it is necessary to control the chemical etching process which is the next important step in the bulk micromachining technology useful to prepare the micromechanical elements. These key parameters of the chemical etching process are the chemical etching rate and the chemical etching time. It is shown that it is possible to calculate the chemical etching rate and the chemical etching time for some specified etching conditions. Such a possibility allows to control the thickness of the micromechanical elements and to eliminate the stress gradient induced by the non-uniform doping and by the misfit dislocations in the silicon micromechanical elements.

  17. Metal concentrations and distribution in paint waste generated during bridge rehabilitation in New York State.

    PubMed

    Shu, Zhan; Axe, Lisa; Jahan, Kauser; Ramanujachary, Kandalam V; Kochersberger, Carl

    2015-09-01

    Between 1950 and 1980, lead and chromium along with other metals have been used in paint coatings to protect bridges from corrosion. In New York State with 4500 bridges in 11 Regions 2385 of the bridges have been rehabilitated and subsequently repainted after 1989 when commercial use of lead based paint was prohibited. The purpose of this research was to address the concentration and distribution of trace metals in the paint waste generated during bridge rehabilitation. Using hypothesis testing and stratified sampling theory, a representative sample size of 24 bridges from across the state was selected that resulted in 117 paint waste samples. Field portable X-ray fluorescence (FP-XRF) analysis revealed metal concentrations ranged from 5 to 168,090 mg kg(-1) for Pb, 49,367 to 799,210 mg kg(-1) for Fe, and 27 to 425,510 mg kg(-1) for Zn. Eighty percent of the samples exhibited lead concentrations greater than 5000 mg kg(-1). The elevated iron concentrations may be attributed to the application of steel grit as an abrasive blasting material routinely used by state Departments of Transportation in the paint removal process. Other metals including Ba and Cr were observed in the paint waste as well. As a result of the paint formulation, metals were found to be associated in the paint waste (Pb correlated with Cr (r=0.85)). The elevated metal concentrations observed raises concern over the potential impact of leaching from this waste stream. PMID:25955694

  18. Boronated dipeptide borotrimethylglycylphenylalanine as a potential boron carrier in boron neutron capture therapy for malignant brain tumors.

    PubMed

    Takagaki, M; Powell, W; Sood, A; Spielvogel, B F; Hosmane, N S; Kirihata, M; Ono, K; Masunaga, S I; Kinashi, Y; Miyatake, S I; Hashimoto, N

    2001-07-01

    Takagaki, M., Ono, K., Masunaga, S-I., Kinashi, Y., Oda, Y., Miyatake, S-I., Hashimoto, N., Powell, W., Sood, A. and Spielvogel, B. F. Boronated Dipeptide Borotrimethylglycylphenylalanine as a Potential Boron Carrier in Boron Neutron Capture Therapy for Malignant Brain Tumors. Radiat. Res. 156, 118-122 (2001).A boronated dipeptide, borotrimethylglycylphenylalanine (BGPA), was synthesized as a possible boron carrier for boron neutron capture therapy (BNCT) for malignant brain tumors. In vitro, at equal concentrations of (10)B in the extracellular medium, BGPA had the same effect in BNCT as p-boronophenylalanine (BPA). Boron analysis was carried out using prompt gamma-ray spectrometry and track-etch autoradiography. The tumor:blood and tumor:normal brain (10)B concentration ratios were 8.9 +/- 2.1 and 3.0 +/- 1.2, respectively, in rats bearing intracranial C6 gliosarcomas using alpha-particle track autoradiography. The IC(50), i.e. the dose capable of inhibiting the growth of C6 gliosarcoma cells by 50% after 3 days of incubation, was 5.9 x 10(-3) M BGPA, which is similar to that of 6.4 x 10(-3) M for BPA. The amide bond of BGPA is free from enzymatic attack, since it is protected from hydrolysis by the presence of a boron atom at the alpha-carbon position of glycine. These results suggest promise for the use of this agent for BNCT of malignant brain tumors. Further preclinical studies of BGPA are warranted, since BGPA has advantages over both BPA and BSH. PMID:11418080

  19. Characteristics of boron-dose enhancer dependent on dose protocol and 10B concentration for BNCT using near-threshold 7Li(p,n)7Be direct neutrons

    NASA Astrophysics Data System (ADS)

    Tanaka, Kenichi; Kobayashi, Tooru; Bengua, Gerard; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2005-01-01

    The dependence of boron-dose enhancer (BDE) characteristics on dose protocol and 10B concentration was evaluated for BNCT using near-threshold 7Li(p,n)7Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP calculations were performed for near-threshold 7Li(p,n)7Be at a proton energy of 1.900 MeV and for a polyethylene BDE. The effect of dose protocol on BDE characteristics was reflected in terms of the optimum BDE thickness needed for maximum TPD which was found to be independent of the treatable dose but was observed to vary for different combinations of the tolerance doses for heavy charged particles and gamma rays. For the 10B concentration dependence, the TPD was increased by increasing the T/N ratio, i.e., the ratio of the 10B concentration in the tumour (10BTumour) to that in the normal tissue (10BNormal), and by increasing 10BTumour and 10BNormal at constant T/N ratio. It was found that the use of BDE becomes unnecessary from the viewpoint of increasing the TPD, when 10BTumour is over a certain level which is decided by the conditions of the dose protocol.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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 ξ with either ξ = 2 or 1 < ξ < 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 ξ 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 μm/s as the most probable value of the speed distribution, but is rather spend on metabolism and growth.

  1. Temperature and emulsifier concentration effects on gallic acid distribution in a model food emulsion.

    PubMed

    Losada-Barreiro, Sonia; Sánchez-Paz, Verónica; Bravo-Díaz, Carlos; Paiva-Martins, Fátima; Romsted, Laurence S

    2012-03-15

    We determined the effects of emulsifier concentration and temperature on the distribution of gallic acid (GA) in a food-grade emulsion composed of 1:9 vol:vol stripped corn oil, acidic water and Tween 20. The distribution of GA can be defined by the partition constant between the aqueous and the interfacial regions, P(W)(I), which was determined by using a kinetic method and the pseudophase kinetic model. Once P(W)(I) is known, determining the distribution of GA is straightforward. Our results show that at least 40% of the total GA is located in the interfacial region of the emulsion at 0.005 volume fraction of Tween 20, and this percentage increases to ca. 85% of the total GA at 0.04 volume fraction of Tween 20. The variation of P(W)(I) with the temperature was used to estimate the thermodynamic parameters for the GA transfer from the aqueous to the interfacial region of the emulsion and the activation parameters for the reaction between 16-ArN(2)(+) and GA in the interfacial region. The free energy of transfer from the aqueous to the interfacial region, ΔG(T)(0,W→I), is negative, the enthalpy of transfer is small and negative, but the entropy of transfer is large and positive. Our results demonstrate that the partitioning of GA in acidic emulsions between aqueous and interfacial regions depends primarily on droplet concentration and is only slightly dependent on temperature. PMID:22284574

  2. Concentration and size distribution of viable bioaerosols during non-haze and haze days in Beijing.

    PubMed

    Gao, Min; Qiu, Tianlei; Jia, Ruizhi; Han, Meilin; Song, Yuan; Wang, Xuming

    2015-03-01

    Accumulation of airborne particulate matter (PM) has profoundly affected the atmospheric environment of Beijing, China. Although studies on health risks have increased, characterization of specific factors that contribute to increased health risks remains an area of needed exploration. Chemical composition studies on PM can readily be found in the literature but researches on biological composition are still limited. In this study, the concentration and size distribution of viable airborne bacteria and fungi were determined in the atmosphere from May to July 2013 in Beijing, China. Samples were collected during non-haze days and haze days based on the value of air quality index (AQI) PM2.5. Multiple linear regression results indicated that concentrations of viable bioaerosol exhibited a negative correlation with PM2.5 (AQI) ranging from 14 to 452. There was a little difference in size distribution of bioaerosol between non-haze and haze days that all airborne bacteria showed skewed trends toward larger sizes and airborne fungi followed a Gaussian distribution. Spearman's correlation analysis showed that a fraction of bioaerosol with fine and coarse particles had negative and positive relations with PM2.5 (AQI), respectively. Moreover, the temporal variation of d g (aerodynamic diameter) of bioaerosol with PM2.5 (AQI) fluctuated from 9:00 to 21:00, which suggested that their deposition pattern would vary during a day. The primary research in this study implied that aerodynamic size variation should be considered in assessing the bioaerosol exposure during haze weather. PMID:25300183

  3. Concentration and particle size distribution of polycyclic aromatic hydrocarbons formed by thermal cooking.

    PubMed

    Saito, E; Tanaka, N; Miyazaki, A; Tsuzaki, M

    2014-06-15

    The concentration and particle size distribution of 19 major polycyclic aromatic hydrocarbons (PAHs) emitted by thermal cooking were investigated. Corn, trout, beef, prawns, and pork were selected for grilling. The PAHs in the oil mist emitted when the food was grilled were collected according to particle size range and analysed by GC/MS. Much higher concentrations of PAHs were detected in the oil mist emitted by grilled pork, trout, and beef samples, which were rich in fat. The main components of the cooking exhaust were 3- and 4-ring PAHs, regardless of food type. The particle size distribution showed that almost all the PAHs were concentrated in particles with diameters of <0.43 μm. For pork, the toxic equivalent of benzo[a]pyrene accounted for 50% of the PAHs in particles with diameters of <0.43 μm. From these results, we estimated that >90% of the PAHs would reach the alveolar region of the lungs. PMID:24491732

  4. Distributions and concentrations of thallium in Korean soils determined by single and sequential extraction procedures.

    PubMed

    Lee, Jin-Ho; Kim, Dong-Jin; Ahn, Byung-Koo

    2015-06-01

    The objectives of this study were to investigate the distribution of thallium in soils collected near suspected areas such as cement plants, active and closed mines, and smelters and to examine the extraction of thallium in the soils using 19 single chemical and sequential chemical extraction procedures. Thallium concentrations in soils near cement plants were distributed between 1.20 and 12.91 mg kg(-1). However, soils near mines and smelters contained relatively low thallium concentrations ranging from 0.18 to 1.09 mg kg(-1). Thallium extractability with 19 single chemical extractants from selected soils near cement plants ranged from 0.10% to 8.20% of the total thallium concentration. In particular, 1.0 M NH4Cl, 1.0 M (NH4)2SO4, and 1.0 M CH3COONH4 extracted more thallium than other extractants. Sequential fractionation results of thallium from different soils such as industrially and artificially contaminated soils varied with the soil properties, especially soil pH and the duration of thallium contamination. PMID:25836266

  5. Bipolaron Hopping Conduction in Boron Carbides

    SciTech Connect

    ASELAGE, TERRENCE L.; EMIN, D.; MCCREADY, STEVEN S.

    1999-09-20

    The electrical conductivities of boron carbides, B{sub 12+x}C{sub 3{minus}x} with 0.1 < x < 1.7, between 300 and 1200K suggest the hopping of a nearly temperature-independent density of small (bi)polarons. The activation energies of the nobilities are low, {approx} 0.16 eV, and are nearly independent of the composition. At lower temperatures, conductivities have non-Arrhenius temperature dependencies and strong sensitivity to carbon concentration. Percolative aspects of low-temperature hopping are evident in this sensitivity to composition. Boron carbides' Seebeck coefficients are anomalous in that (1) they are much larger than expected from boron carbides' large carrier densities and (2) they depend only weakly on the carrier density. Carrier-induced softening of local vibrations gives contributions to the Seebeck coefficient that mirror the magnitudes and temperature dependencies found in boron carbides.

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

    PubMed

    Edward Raja, Chellaiah; Omine, Kiyoshi

    2013-08-01

    Boron is an essential micronutrient for plants, but can above certain concentrations be toxic to living organisms. A major environmental concern is the removal of boron from contaminated water and fly ash. For this purpose, the samples were collected from a fly ash dumping site, Nagasaki prefecture, Japan. The chemical characteristics and heavy metal concentration of the samples were performed by X-ray fluorescent analysis and leaching test. For bacterial analysis, samples were collected in sterile plastic sheets and isolation was carried out by serial dilution method. The boron tolerant isolates that showed values of maximum inhibitory concentration toward boron ranging from 100 to 260 mM level were screened. Based on 16S rRNA sequencing and phylogenetic analysis, the isolates were most closely related to the genera Bacillus, Lysinibacillus, Microbacterium and Ralstonia. The boron tolerance of these strains was also associated with resistant to several heavy metals, such as As (III), Cr (VI), Cd, Cu, Pb, Ni, Se (III) and Zn. Indeed, these strains were arsenic oxidizing bacteria confirmed by silver nitrate test. These strains exhibited their salt resistances ranging from 4 to 15 % were determined in Trypticase soy agar medium. The boron tolerant strains were capable of removing 0.1-2.0 and 2.7-3.7 mg l(-1) boron from the medium and fly ash at 168 h. Thus, we have successfully identified the boron tolerant and removal bacteria from a fly ash dumping site for boron remediation. PMID:23212536

  7. Influence of urban climate upon distribution of airborne Deuteromycete spore concentrations in Mexico City

    NASA Astrophysics Data System (ADS)

    Calderón, C.; Lacey, J.; McCartney, A.; Rosas, I.

    The effect of an urban climate upon the spatial and temporal distribution of Deuteromycete spores was studied during 1991 using Burkard volumetric spore traps in two areas of Mexico City with different degrees of urbanization. Deuteromycete conidia formed the largest component of the total airborne fungal spore load in the atmosphere of Mexico City, contributing 52% of the spores trapped in an urban-residential area (southern area) and 65% of those in an urban-commercial area (central area). Among the most common spore types, Cladosporium and Alternaria showed a marked seasonal periodicity with significant differences in concentration (P<0.05) between the dry and wet seasons. Maximum conidial concentrations were found during the end of the wet season and the beginning of the cool, dry season (October-December). Daily mean concentrations of the predominant airborne spore types did not differ significantly between the southern and central areas. Daily mean spore concentrations were significantly correlated (P<0.05) in southern and central areas with maximum temperature (south, r = -0.35 central, r = -0.40) and relative humidity (south, r = 0.43; central, r = 0.29) from the previous day. Moreover, multiple regression analysis of spore concentrations with several meteorological factors showed significant interactions between fungal spores, relative humidity and maximum temperature in both areas. The diurnal periodicity of Cladosporium conidia characteristically showed two or three peaks in concentration during the day at 0200-0400, 1400 and 2000-2200 hours, while that of Alternaria showed only one peak (1200 to 2000 hours) in both areas. Maximum concentrations of these spores generally occurred 2-4 h earlier in the southern than in the central area. The lag in reaching maximum concentrations in the central area probably resulted from differences in the local conditions between the study areas, and from spores transported aerially into the city from distant sources. The analysis of maximum hourly concentrations of Cladosporium and Alternaria spores during 1 month of the dry season (February), and another month of the wet season (September) showed significant differences between the two study areas. Environmental factors and sources (green areas) affected diurnal changes in conidial concentration in the southern area (urbanization index, UI, 0.25), but not in the central area (UI 0.97). In general, spore concentrations were greatest in the southern area when relative humidities were low, and temperatures and wind velocities were high. It was difficult to establish effects of climatic factors on the spore concentration in the city centre. This probably results from the large amounts of air pollution, the heat island phenomenon, and from the distant origin of trapped conidia obviating aerial transport. Nevertheless, the seasonal and diurnal distributions of conidia found were similar to those reported for other tropical regions of the world.

  8. Concentrations, size distributions and temporal variations of fluorescent biological aerosol particles in southern tropical India

    NASA Astrophysics Data System (ADS)

    Valsan, Aswathy; Krishna R, Ravi; CV, Biju; Huffman, Alex; Poschl, Ulrich; Gunthe, Sachin

    2015-04-01

    Biological aerosols constitute a wide range of dead and alive biological materials and structures that are suspended in the atmosphere. They play an important role in the atmospheric physical, chemical and biological processes and health of living being by spread of diseases among humans, plants, and, animals. The atmospheric abundance, sources, physical properties of PBAPs as compared to non-biological aerosols, however, is poorly characterized. The Indian tropical region, where large fraction of the world's total population is residing, experiences a distinctive meteorological phenomenon by means of Indian Summer Monsoon (IMS). Thus, the properties and characteristics of biological aerosols are also expected to be very diverse over the Indian subcontinent depending upon the seasons. Here we characterize the number concentration and size distribution of Fluorescent Biological Aerosol Particles (FBAP) at a high altitude continental site, Munnar (10.09 N, 77.06 E; 1605 m asl) in South India during the South-West monsoon, which constitute around 80 percent of the annual rainfall in Munnar. Continuous three months measurements (from 01 June 2014 to 21 Aug 2104) FBAPs were carried out at Munnar using Ultra Violet Aerodynamic Particle Sizer (UVAPS) during IMS. The mean number and mass concentration of coarse FBAP averaged over the entire campaign was 1.7 x 10-2 cm-3 and 0.24 µg m-3 respectively, which corresponds to 2 percent and 6 percent of total aerosol particle number and mass concentration. In agreement to other previous measurements the number size distribution of FBAP also peaks at 3.2 micron indicating the strong presence of fungal spores. This was also supported by the Scanning Electron Microscopic analysis of bioaerosols on filter paper. They also displayed a strong diurnal cycle with maximum concentration occurring at early morning hours. During periods of heavy and continuous rain where the wind is consistently blowing from South-West direction it was observed that the FBAP concentrations were very low. This may be due to the clean marine influx coming over the Indian Ocean and due to continuous wash out during the rain. While in case of sporadic rain events with fluctuating wind direction, high FBAP concentration was noticed. However such a similar trend was not observed for total aerosol particle concentration. The detailed results will be presented.

  9. Real-time optical fiber sensing of phytoplankton for studies in size distribution, concentration, and biomass

    NASA Astrophysics Data System (ADS)

    Chan, Robert K.; Chen, Ce; Cheng, S. K.

    1995-09-01

    An optical fiber laser-doppler system has ben developed to detect both the laser-induced- fluorescence (LIF) signal and the laser doppler signal of phytoplankton traversing through a measurement volume. From the two measurement, the size distribution, concentration, biomass, and the amount of chlorophyll present can be determined. Our apparatus have demonstrated successfully that it can resolve distinctly the size distribution of two species of phytoplankton (Chlorella and Scenedesmus). For phytoplankton, these two species do not have mark differences in size, one being less than 10 micrometers while the other is approximately 25 micrometers , and yet our measurement gave very satisfactory results. The result obtained clearly indicates that our optical system can produce accurate and liable size measurement and is suitable to be further develop into a practical in situ field instrument.

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

    SciTech Connect

    Farkas, T.; Sepaniak, M.J.; Guiochon, G.

    1997-08-01

    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.

  11. Modeling extreme PM10 concentration in Malaysia using generalized extreme value distribution

    NASA Astrophysics Data System (ADS)

    Hasan, Husna; Mansor, Nadiah; Salleh, Nur Hanim Mohd

    2015-05-01

    Extreme PM10 concentration from the Air Pollutant Index (API) at thirteen monitoring stations in Malaysia is modeled using the Generalized Extreme Value (GEV) distribution. The data is blocked into monthly selection period. The Mann-Kendall (MK) test suggests a non-stationary model so two models are considered for the stations with trend. The likelihood ratio test is used to determine the best fitted model and the result shows that only two stations favor the non-stationary model (Model 2) while the other eleven stations favor stationary model (Model 1). The return level of PM10 concentration that is expected to exceed the maximum once within a selected period is obtained.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  13. Imaging shear stress distribution and evaluating the stress concentration factor of the human eye

    PubMed Central

    Joseph Antony, S.

    2015-01-01

    Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future. PMID:25754336

  14. Measurement technique for methane concentration by wavelength scanning of a distributed-feedback laser

    NASA Astrophysics Data System (ADS)

    Wang, H.; Wang, Q.; Chang, J.; Zhang, X.; Zhang, S.; Ni, J.

    2008-04-01

    A new technique which takes advantage of distributed-feedback (DFB) laser wavelength scanning to measure methane concentration is presented. A wavelength scan of the methane absorption peak at 1665.9 nm is realized using sawtooth modulation of the current injected to a DFB laser. A reference methane gas cell is used to find the methane absorption peak around 1666 nm, and normalization is used to reduce outside influences such as power drift and fiber loss. The concentration is derived by arithmetic processing of the absorption coefficient of the methane gas. An application test is carried out in a coal mine and a long-term precision of 0.05% is achieved.

  15. Imaging shear stress distribution and evaluating the stress concentration factor of the human eye

    NASA Astrophysics Data System (ADS)

    Joseph Antony, S.

    2015-03-01

    Healthy eyes are vital for a better quality of human life. Historically, for man-made materials, scientists and engineers use stress concentration factors to characterise the effects of structural non-homogeneities on their mechanical strength. However, such information is scarce for the human eye. Here we present the shear stress distribution profiles of a healthy human cornea surface in vivo using photo-stress analysis tomography, which is a non-intrusive and non-X-ray based method. The corneal birefringent retardation measured here is comparable to that of previous studies. Using this, we derive eye stress concentration factors and the directional alignment of major principal stress on the surface of the cornea. Similar to thermometers being used for monitoring the general health in humans, this report provides a foundation to characterise the shear stress carrying capacity of the cornea, and a potential bench mark for validating theoretical modelling of stresses in the human eye in future.

  16. Concentration and distribution of heavy metals in urban airborne particulate matter in Frankfurt am Main, Germany.

    PubMed

    Zereini, Fathi; Alt, Friedrich; Messerschmidt, Jürgen; Wiseman, Clare; Feldmann, Ingo; von Bohlen, Alex; Müller, Jürgen; Liebl, Karlheinz; Püttmann, Wilhelm

    2005-05-01

    Heavy metal concentrations were measured in airborne dust collected at three sites with different traffic densities from August 2001 to July 2002 in the Frankfurt am Main area. Bulk samples of particulate matter (PM) with an aerodynamic equivalent diameter of <22 microm were collected on cellulose nitrate filters using air filtration devices. Fractionated samples of PM with an aerodynamic equivalent diameter of <10 microm were collected using an eight-stage Andersen impactor. Pb, Cd, Mn, Ni, Zn, V, As, Sb, Cu, Cr, Co, and Ce were determined by inductively coupled plasma sector field mass spectrometry, Pt and Rh were determined by adsorptive voltammetry, and Pd was determined by total reflection X-ray fluorescence analysis. The results show that the highest airborne heavy metal concentrations occurred at the main street with a large volume of traffic. With the exception of Co, V, Ce, and Mn, the heavy metals had an elevated enrichment factor compared to their concentrations in the continental crust. The main street site was especially contaminated with Sb, Zn, Cu, V, and Ni. Motor vehicles are the likely source of emissions. With the exception of Cr, Cu, and Zn, most of the airborne heavy metal concentrations determined for impactor samples deviate slightly from the results for total airborne dust. Heavy metal particle size distributions can be divided into three groups. For metals such as As, Cd, Pb, and V, the main fraction can be found in fine particles with a diameter of <2.1 microm, whereas Ce, Cr, Co, and Ni occur mainly in coarse particles with a diameter of >2.1 microm. Cu, Mn, Sb, Zn, Pt, Pd, and Rh occur in high concentrations in the medium range of the impactor stages (particle diameters of 1.1-4.7 microm). Metal concentrations in fine dust particles are needed to assess the human health risks of their inhalation. PMID:15926542

  17. Miniaturized concentrator arrays as compact angle transformers for light collection and distribution

    NASA Astrophysics Data System (ADS)

    Bitterli, Roland; Scharf, Toralf; Haug, Franz Josef

    2013-03-01

    Efficient light management is one of the key issues in modern energy conversion systems, might it be to collect optical power or to redistribute light generated by high power light emitting diodes. One problem remains: How can one realize small size elements with high quality of light management. We propose a novel scheme by using miniaturized angle transformers or concentrators that have size of several millimeters. none In this size range diffraction effects play rarely a role and the design can be based on classical ray tracing. Dimensions are chosen to allow effective solution for high power light emitting diodes as well as solar cells. In most solar cell designs, the photocurrent is extracted through a conducting window layer in combination with a silver grid at the front of the device. The trade-off between series resistance and shadowing requires either buried contacts or screen printing of narrow lines with high aspect ratio. We propose an alternate approach where an array of parabolic concentrators directs the incoming light into the cell. The front metallization can thus be extended over the area between the paraboloids without shadowing loss. High power light emitting diodes are source with certain far field distribution and composed often out of several chips. Applying the concentrator array technology not on the whole source but locally on each chip promises small and effective solutions. We demonstrate realization of linear and hexagonal arrays of micro-concentration systems, discuss details of application and results of simulation of their optical properties in applications.

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

    PubMed Central

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

    1994-01-01

    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. PMID:8142252

  19. Boron nitride - Composition, optical properties, and mechanical behavior

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  20. Boron nitride: Composition, optical properties and mechanical behavior

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Chu, T. L.

    1975-01-01

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

  2. Middle East measurements of concentration and size distribution of aerosol particles for coastal zones

    NASA Astrophysics Data System (ADS)

    Bendersky, Sergey; Kopeika, Norman S.; Blaunstein, Natan S.

    2005-10-01

    Recently, an extension of the Navy Aerosol Model (NAM) was proposed based on analysis of an extensive series of measurements at the Irish Atlantic Coast and at the French Mediterranean Coast. We confirm the relevance of that work for the distant eastern Meditteranean and extend several coefficients of that coastal model, proposed by Piazzola et al. for the Meditteranean Coast (a form of the Navy Aerosol Model), to midland Middle East coastal environments. This analysis is based on data collected at three different Middle East coastal areas: the Negev Desert (Eilat) Red Sea Coast, the Sea of Galilee (Tiberias) Coast, and the Mediterranean (Haifa) Coast. Aerosol size distributions are compared with those obtained through measurements carried out over the Atlantic, Pacific, and Indian Ocean Coasts, and Mediterranean, and Baltic Seas Coasts. An analysis of these different results allows better understanding of the similarities and differences between different coastal lake, sea, and open ocean zones. It is shown that in the coastal regions in Israel, compared to open ocean and other sea zones, larger differences in aerosol particle concentration are observed. The aerosol particle concentrations and their dependences on wind speed for these coastal zones are analyzed and discussed. We propose to classify the aerosol distribution models to either: 1. a coastal model with marine aerosol domination; 2. a coastal model with continental aerosol domination (referred to as midland coast in this work); or 3. a coastal model with balanced marine and continental conditions.

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

    USGS Publications Warehouse

    Haines, E.L.; Zartman, R.E.

    1973-01-01

    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 (1 ng = 10-9 g). 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 = 10-6 g). 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. ?? 1973.

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

    NASA Technical Reports Server (NTRS)

    Haines, E. L.; Zartman, R. E.

    1973-01-01

    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. 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 - those which have less than 10 ng/g and those which have 100 to 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 microgram/g. Very little uranium is associated with microcrystals of apatite. These 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.

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

    NASA Astrophysics Data System (ADS)

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

    2005-04-01

    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.

  6. The sorption capacity of boron on anionic-exchange resin

    SciTech Connect

    Lou, J.; Foutch, G.L.; Na, J.W.

    1999-11-01

    Boron sorption capacities on anionic-exchange resins vary with temperature, concentration, and resin crosslinkage. A semiempirical correlation, developed from boron solution chemistry, is presented to account for these variations. The relationship, based on boron chemistry and changes in Gibb's energy, can be stated approximately as Q = a{sub 1}C{sub B}{sup a{sub 2}}Z{sup a{sub 3}} exp[{minus}(a{sub 4}T + a{sub 5}T{sup 2} + a{sub 6}Z{sup 0.5})]. Correlation parameters, which vary with resin type, are evaluated experimentally. Parameter values for macroporous resin Diaion PA 300 and for gel-type resins Diaion SA10 and Amberlite IRN 78LC are presented. The resulting expression is used to determine boron sorption and desorption limitations on ion exchangers at various temperatures and concentrations, and to determine the interfacial boron concentration in equilibrium and rate models.

  7. Droplet Size Distributions as a function of rainy system type and Cloud Condensation Nuclei concentrations

    NASA Astrophysics Data System (ADS)

    Cecchini, Micael A.; Machado, Luiz A. T.; Artaxo, Paulo

    2014-06-01

    This work aims to study typical Droplet Size Distributions (DSDs) for different types of precipitation systems and Cloud Condensation Nuclei concentrations over the Vale do Paraíba region in southeastern Brazil. Numerous instruments were deployed during the CHUVA (Cloud processes of tHe main precipitation systems in Brazil: a contribUtion to cloud resolVing modeling and to the GPM) Project in Vale do Paraíba campaign, from November 22, 2011 through January 10, 2012. Measurements of CCN (Cloud Condensation Nuclei) and total particle concentrations, along with measurements of rain DSDs and standard atmospheric properties, including temperature, pressure and wind intensity and direction, were specifically made in this study. The measured DSDs were parameterized with a gamma function using the moment method. The three gamma parameters were disposed in a 3-dimensional space, and subclasses were classified using cluster analysis. Seven DSD categories were chosen to represent the different types of DSDs. The DSD classes were useful in characterizing precipitation events both individually and as a group of systems with similar properties. The rainfall regime classification system was employed to categorize rainy events as local convective rainfall, organized convection rainfall and stratiform rainfall. Furthermore, the frequencies of the seven DSD classes were associated to each type of rainy event. The rainfall categories were also employed to evaluate the impact of the CCN concentration on the DSDs. In the stratiform rain events, the polluted cases had a statistically significant increase in the total rain droplet concentrations (TDCs) compared to cleaner events. An average concentration increase from 668 cm- 3 to 2012 cm- 3 for CCN at 1% supersaturation was found to be associated with an increase of approximately 87 m- 3 in TDC for those events. For the local convection cases, polluted events presented a 10% higher mass weighted mean diameter (Dm) on average. For the organized convection events, no significant results were found.

  8. Spatial and temporal distribution of pesticide air concentrations in Canadian agricultural regions

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Tuduri, Ludovic; Harner, Tom; Blanchard, Pierrette; Waite, Don; Poissant, Laurier; Murphy, Clair; Belzer, Wayne; Aulagnier, Fabien; Li, Yi-Fan; Sverko, Ed

    The Canadian Pesticide Air Sampling Campaign was initiated in 2003 to assess atmospheric levels of pesticides, especially currently used pesticides (CUPs) in agricultural regions across Canada. In the first campaign during the spring to summer of 2003, over 40 pesticides were detected. The spatial and temporal distribution of pesticides in the Canadian atmosphere was shown to reflect the pesticide usage in each region. Several herbicides including triallate, bromoxynil, MCPA, 2,4-D, dicamba, trifluralin and ethalfluralin were detected at highest levels at Bratt's Lake, SK in the prairie region. Strong relationships between air concentrations and dry depositions were observed at this site. Although no application occurred in the Canadian Prairies in 2003, high air concentrations of lindane ( γ-hexachlorocyclohexane) were still observed at Bratt's Lake and Hafford, SK. Two fungicides (chlorothalonil and metalaxyl) and two insecticides (endosulfan and carbofuran) were measured at highest levels at Kensington, PEI. Maximum concentrations of chlorpyrifos and metolachlor were found at St. Anicet, QC. The southern Ontario site, Egbert showed highest concentration of alachlor. Malathion was detected at the highest level at the west coast site, Abbotsford, BC. In case of legacy chlorinated insecticides, high concentrations of DDT, DDE and dieldrin were detected in British Columbia while α-HCH and HCB were found to be fairly uniform across the country. Chlordane was detected in Ontario, Québec and Prince Edward Island. This study demonstrates that the sources for the observed atmospheric occurrence of pesticides include local current pesticide application, volatilization of pesticide residues from soil and atmospheric transport. In many instances, these data represent the first measurements for certain pesticides in a given part of Canada.

  9. Spatial and temporal distributions of aerosol concentrations and depositions in Asia during the year 2010.

    PubMed

    Park, Soon-Ung; Lee, In-Hye; Joo, Seung Jin

    2016-01-15

    Aerosol Modeling System (AMS) that is consisted of the Asian Dust Aerosol Model2 (ADAM2) and the Community Multi-scale Air Quality (CMAQ) modeling system has been employed to document the spatial distributions of the monthly and the annual averaged concentration of both the Asian dust (AD) aerosol and the anthropogenic aerosol (AA), and their total depositions in the Asian region for the year 2010. It is found that the annual mean surface aerosol (PM10) concentrations in the Asian region affect in a wide region as a complex mixture of AA and AD aerosols; they are predominated by the AD aerosol in the AD source region of northern China and Mongolia with a maximum concentration exceeding 300 μg m(-3); AAs are predominated in the high pollutant emission regions of southern and eastern China and northern India with a maximum concentration exceeding 110 μg m(-3); while the mixture of AA and AD aerosols is dominated in the downwind regions extending from the Yellow Sea to the Northwest Pacific Ocean. It is also found that the annual total deposition of aerosols in the model domain is found to be 485 Tg (372 Tg by AD aerosol and 113 Tg by AA), of which 66% (319 Tg) is contributed by the dry deposition (305 Tg by AD aerosol and 14 Tg by AA) and 34% (166 Tg) by the wet deposition (66 Tg by AD aerosol and 100 Tg by AA), suggesting about 77% of the annual total deposition being contributed by the AD aerosol mainly through the dry deposition process and 24% of it by AA through the wet deposition process. The monthly mean aerosol concentration and the monthly total deposition show a significant seasonal variation with high in winter and spring, and low in summer. PMID:26520259

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

    PubMed

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

    2012-08-21

    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

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

    PubMed Central

    2010-01-01

    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 37C, ? 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. PMID:20678197

  12. 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...

  13. Roles of ATR1 paralogs YMR279c and YOR378w in boron stress tolerance

    SciTech Connect

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

    2011-06-17

    Highlights: {yields} ATR1 paralog YMR279c plays role in boron detoxification. {yields} YMR279c overexpression lowers cytoplasmic boron levels. {yields} ATR1 paralog YOR378w has no roles in boron stress response. -- Abstract: 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 understand whether they participate in boron stress tolerance in yeast. Even though these genes share homology with ATR1, neither their deletion rendered cells boron sensitive nor their expression was significantly upregulated by boron treatment. However, expression of YMR279, but not YOR378w, from the constitutive GAPDH promoter on a high copy plasmid provided remarkable boron resistance by decreasing intracellular boron levels. Thus our results suggest the presence of a third boron exporter, YMR279c, which functions similar to ATR1 and provides boron resistance in yeast.

  14. Occurrence and variability of iodinated trihalomethanes concentrations within two drinking-water distribution networks.

    PubMed

    Ioannou, Panagiotis; Charisiadis, Pantelis; Andra, Syam S; Makris, Konstantinos C

    2016-02-01

    Non-iodo-containing trihalomethanes (TTHM) are frequently detected in chlorinated tap water and currently regulated against their carcinogenic potential. Iodinated THM (ITHM) may also form in disinfected with chlorine waters that are high in iodine content, but little is known about their magnitude and variability within the drinking-water pipe distribution network of urban areas. The main objective of this study was to determine the magnitude and variability of ITHM and TTHM levels and their corresponding daily intake estimates within the drinking water distribution systems of Limassol and Nicosia cities of Cyprus, using tap samples collected from individual households (n=37). In Limassol, mean household tap water ITHM and TTHM levels was 0.58 and 38 μg L(-1), respectively. Dichloroiodomethane (DCIM) was the dominant species of the two measured ITHM compounds accounting for 77% of total ITHM and in the range of 0.032 and 1.65 μg L(-1). The range of DCIM concentrations in Nicosia tap water samples was narrower (0.032 - 0.848 μg L(-1)). Mean total iodine concentration in tap water samples from the seaside city of Limassol was 15 μg L(-1) and approximately twice to those observed in samples from the mainland Nicosia city. However, iodine concentrations did not correlate with the ITHM levels. The calculated chronic daily intake rates of ITHM were low when compared with those of TTHM, but because of their widespread occurrence in tap water and their enhanced mammalian cell toxicity, additional research is warranted to assess the magnitude and variability of human ITHM exposures. PMID:26599150

  15. Effect of solids concentration distribution on the flue gas desulfurization process.

    PubMed

    Zhang, Jie; You, Changfu; Qi, Haiying; Chen, Changhe; Xu, Xuchang

    2006-06-15

    A dry flue gas desulfurization (FGD) process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. Various fresh sorbent distribution types and internal structures were modeled numerically to investigate their effect on the gas-solid flow and sulfate reaction characteristics. Experimental results show that, after the fresh sorbent supply was stopped, the desulfurization efficiency declined rapidly even though the sorbent recirculation was maintained. Therefore, the fresh sorbent is the main contributor to the desulfurization process and the primary effect of the recirculated sorbent was to evenly distribute the fresh sorbent and to prolong the sorbent particle residence time. The numerical results demonstrate thatthe desulfurization efficiency varied greatly for the various fresh sorbent bottom injection methods. The desulfurization efficiency of the bottom-even injection method was 1.5 times that of the bottom two-sided injection method. Internal structures effectively improved the fresh sorbent solids concentration distribution and the desulfurization efficiency. Optimized internal structures increased the desulfurization efficiency of the bottom two-sided injection method by 46%, so that it was very close to that of the bottom-even injection method with only a 4.6% difference. PMID:16830575

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

    PubMed

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

    2007-03-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    1986-11-01

    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.

  18. Measurements of CO concentration distribution for Mars atmospheric entry by combining OES and TDLAS

    NASA Astrophysics Data System (ADS)

    Lin, Xin; Chen, Lianzhong; Ou, Dongbin; Li, Fei; Yu, Xilong

    2015-05-01

    Shock tube experiments are carried out to study the physical and chemical processes during a vehicle entry into the Mars atmosphere using optical emission spectroscopy (OES) and tunable diode laser absorption spectroscopy (TDLAS). Gas temperature and CO concentration distribution are diagnosed behind a shock wave in a CO2-N2 mixture with two different conditions of initial pressure and velocity. The strong shock wave is established in a shock tube driven by combustion of hydrogen and oxygen. Time-resolved spectra of the Δv = 0 sequence of the B2Σ+→X2Σ+ electronic transition of CN have been observed through OES. A precise analysis of the CN violet spectra is performed and used to determine rotational and vibrational temperatures. Two absorption lines in the first overtone band of CO near 2.33 μm, are selected from a HITRAN simulation to calibrate laser wavelength and detect the CO concentration. Combined with these temperature results using OES, CO concentrations in the thermal equilibrium region are derived, which are 2.91 × 1012 cm-3 and 1.01 × 1013 cm-3, corresponding to equilibrium temperatures equal to 7000 ± 400 K and 6000 ± 300 K in low and high pressure conditions, respectively.

  19. Spatial Distribution of Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Soils from Bursa, Turkey.

    PubMed

    Karaca, Gizem

    2016-02-01

    The objectives of this study were to identify regional variations in soil polycyclic aromatic hydrocarbon (PAH) contamination in Bursa, Turkey, and to determine the distributions and sources of various PAH species and their possible sources. Surface soil samples were collected from 20 different locations. The PAH concentrations in soil samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAH concentrations (∑12 PAH) varied spatially between 8 and 4970 ng/g dry matter (DM). The highest concentrations were measured in soils taken from traffic+barbecue+ residential areas (4970 ng/g DM) and areas with cement (4382 ng/g DM) and iron-steel (4000 ng/g DM) factories. In addition, the amounts of ∑7 carcinogenic PAH ranged from 1 to 3684 ng/g DM, and between 5 and 74 % of the total PAHs consisted of such compounds. Overall, 4-ring PAH compounds (Fl, Pyr, BaA and Chr) were dominant in the soil samples, with 29-82 % of the ∑12 PAH consisting of 4-ring PAH compounds. The ∑12 BaPeq values ranged from 0.1 to 381.8 ng/g DM. Following an evaluation of the molecular diagnostic ratios, it was concluded that the PAH pollution in Bursa soil was related to pyrolytic sources; however, the impact of petrogenic sources should not be ignored. PMID:26658619

  20. Spatial distribution patterns of molybdenum (Mo) concentrations in potable groundwater in Northern Jordan.

    PubMed

    Al Kuisi, Mustafa; Al-Hwaiti, Mohammad; Mashal, Kholoud; Abed, Abdulkader M

    2015-03-01

    Two hundred and three groundwater samples were collected during March 2011 to June 2012 from the B2/A7 aquifer water supply wells of northern part of Jordan. The physicochemical properties were analyzed in situ for the major cations, anions, while certain heavy metals were analyzed in the laboratory. Some oilshale rock samples were geochemically analyzed. The Upper Cretaceous aquifer (B2/A7) is used as water supply for most of the communities in the study area. It consists of limestone, marly limestone, bedded chert, and minor phosphorite. Hydrochemical results from the B2/A7 aquifer indicate two main water types: alkaline-earth water (CaHCO3) and alkaline-earth water with high alkaline component (NaHCO3 (-), Na2SO4). Standard column leaching experiments on oilshale rock samples and the R-mode factor analysis suggest that the sources for elevated Mo concentrations in the groundwater of certain parts of northern Jordan are attributed to water-oilshale interaction, mobility of Mo down to the groundwater and the extensive use of fertilizers within these areas. Molybdenum (Mo) concentrations in the groundwater water range from 0.07 to 1.44 mg/L with an average value of 98 ?g/L. They are found to exceed the JISM and WHO guidelines in two areas in northern part of Jordan. Spatial distribution of Mo, using ordinary kriging techniques and the resulting map, shows high Mo concentration in the northwestern part near Wadi Al Arab area reaching concentrations of 650 ?g/L and in the southeastern corner of the investigated area, south of Al Ukaydir village, with an average concentration of 468 ?g/L. Both areas are characterized by extensive oilshale exposures with average concentration of 11.7 mg/kg Mo and intensive agricultural activities. These two areas represent approximately 33 % of the groundwater in the northern part of Jordan. Mobility of Mo to the groundwater in northern part of Jordan is attributed to two mechanisms. First, there is reductive dissolution of Fe-oxide, which releases substantial adsorbed Mo concentrations. Secondly, there is oxidation of Mo into dissolved forms in sulfide organic-rich system. PMID:25720968

  1. Monte Carlo simulation of boron doping profile of fin and trench structures by plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Shahsenov, Izat S.; Miakonkikh, Andrey V.; Rudenko, Kostantin V.

    2014-12-01

    Plasma immersion ion implantation into fins and trenches at elevated pressures is simulated. In the present work we calculate boron concentration distribution in the sample accounting for ion scattering in plasma sheath and geometric shadowing effects (ions at certain angle of incidence couldn't achieve shadowed part of trench wall and bottom). First, energy and angle distribution of ions passed through the plasma sheath to the sample surface is obtained. These data are used to calculate boron concentration distribution in the sample. Pressure range is 30-300 mTorr, plasma electron temperature 5 eV, plasma density 1010-1012 cm-3. The degree of conformity increases with the pressure raises and decreases with the density of plasma.

  2. Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

    NASA Astrophysics Data System (ADS)

    Krivezhenko, Dina S.; Drobyaz, Ekaterina A.; Bataev, Ivan A.; Chuchkova, Lyubov V.

    2015-10-01

    An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to an enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.

  3. Characteristics of inhalable particulate matter concentration and size distribution from power plants in China

    SciTech Connect

    Honghong Yi; Jiming Hao; Lei Duan; Xinghua Li; Xingming Guo

    2006-09-15

    The collection efficiency of particulate emission control devices (PECDs), particulate matter (PM) emissions, and PM size distribution were determined experimentally at the inlet and outlet of PECDs at five coal-fired power plants. Different boilers, coals, and PECDs are used in these power plants. Measurement in situ was performed by an electrical low-pressure impactor with a sampling system, which consisted of an isokinetic sampler probe, precut cyclone, and two- stage dilution system with a sample line to the instruments. The size distribution was measured over a range from 0.03 to 10 {mu}m. Before and after all of the PECDs, the particle number size distributions display a bimodal distribution. The PM2.5 fraction emitted to atmosphere includes a significant amount of the mass from the coarse particle mode. The controlled and uncontrolled emission factors of total PM, inhalable PM (PM10), and fine PM (PM2.5) were obtained. Electrostatic precipitator (ESP) and baghouse total collection efficiencies are 96.38 99.89% and 99.94%, respectively. The minimum collection efficiency of the ESP and the baghouse both appear in the particle size range of 0.1 1 0 {mu}m. In this size range, ESP and baghouse collection efficiencies are 85.79 98.6% and 99.54%. Real- time measurement shows that the mass and number concentration of PM10 will be greatly affected by the operating conditions of the PECDs. The number of emitted particles increases with increasing boiler load level because of higher combustion temperature. During test run periods, the data reproducibility is satisfactory. 19 refs., 11 figs., 6 tabs.

  4. The structure of boron in boron fibres

    NASA Technical Reports Server (NTRS)

    Bhardwaj, J.; Krawitz, A. D.

    1983-01-01

    The structure of noncrystalline, chemically vapour-deposited boron fibres was investigated by computer modelling the experimentally obtained X-ray diffraction patterns. The diffraction patterns from the models were computed using the Debye scattering equation. The modelling was done utilizing the minimum nearest-neighbour distance, the density of the model, and the broadening and relative intensity of the various peaks as boundary conditions. The results suggest that the fibres consist of a continuous network of randomly oriented regions of local atomic order, about 2 nm in diameter, containing boron atoms arranged in icosahedra. Approximately half of these regions have a tetragonal structure and the remaining half a distorted rhombohedral structure. The model also indicates the presence of many partial icosahedra and loose atoms not associated with any icosahedra. The partial icosahedra and loose atoms indicated in the present model are in agreement with the relaxing sub-units which have been suggested to explain the anelastic behavior of fibre boron and the loosely bound boron atoms which have been postulated to explain the strengthening mechanism in boron fibres during thermal treatment.

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

    PubMed

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

    2011-09-01

    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

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

    PubMed

    Fernàndez-Garcia, D; Sanchez-Vila, X

    2011-03-01

    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

  7. Trace elements in particulate matter from metropolitan regions of Northern China: Sources, concentrations and size distributions.

    PubMed

    Pan, Yuepeng; Tian, Shili; Li, Xingru; Sun, Ying; Li, Yi; Wentworth, Gregory R; Wang, Yuesi

    2015-12-15

    Public concerns over airborne trace elements (TEs) in metropolitan areas are increasing, but long-term and multi-site observations of size-resolved aerosol TEs in China are still lacking. Here, we identify highly elevated levels of atmospheric TEs in megacities and industrial sites in a Beijing-Tianjin-Hebei urban agglomeration relative to background areas, with the annual mean values of As, Pb, Ni, Cd and Mn exceeding the acceptable limits of the World Health Organization. Despite the spatial variability in concentrations, the size distribution pattern of each trace element was quite similar across the region. Crustal elements of Al and Fe were mainly found in coarse particles (2.1-9 μm), whereas the main fraction of toxic metals, such as Cu, Zn, As, Se, Cd and Pb, was found in submicron particles (<1.1 μm). These toxic metals were enriched by over 100-fold relative to the Earth's crust. The size distributions of Na, Mg, K, Ca, V, Cr, Mn, Ni, Mo and Ba were bimodal, with two peaks at 0.43-0.65 μm and 4.7-5.8 μm. The combination of the size distribution information, principal component analysis and air mass back trajectory model offered a robust technique for distinguishing the main sources for airborne TEs, e.g., soil dust, fossil fuel combustion and industrial emissions, at different sites. In addition, higher elemental concentrations coincided with westerly flow, indicating that polluted soil and fugitive dust were major sources of TEs on the regional scale. However, the contribution of coal burning, iron industry/oil combustion and non-ferrous smelters to atmospheric metal pollution in Northern China should be given more attention. Considering that the concentrations of heavy metals associated with fine particles in the target region were significantly higher than those in other Asian sites, the implementations of strict environmental standards in China are required to reduce the amounts of these hazardous pollutants released into the atmosphere. PMID:26278373

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

    NASA Astrophysics Data System (ADS)

    Hassan, Salwa Kamal Mohamed

    2012-07-01

    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 μm, >38-45 μm and >45-63 μm. 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 μm), whereas Al, Fe and Cu were detected in significantly (p < 0.01) higher concentrations in dust of the large particle size (>45-63 μm). The average concentrations of the individual metals in dust of the small particle size (<38 μm) were 268, 196.4 and 254.49 μg gm-1 for Pb, 49.6, 43.5 and 46.66 μg gm-1 for Ni, 2.86, 2.15 and 2.71 μg gm-1 for Cd, 4340, 3796 and 2602 μg gm-1 for Al, 2860, 2200 and 2004 μg gm-1 for Fe, 209.25, 152.3 and 103.26 μg gm-1 for Zn, 4.1, 2.88 and 1.96 μg gm-1 for Co, 85.99, 74.06 and 83.17 μg gm-1 for Cr and 168.2, 156.5 and 122.02 μg 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 μg 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.

  9. Magnetron sputtered boron films

    DOEpatents

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

    1998-06-16

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

  10. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1998-01-01

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

  11. Ranges and moments of depth distributions of boron and phosphorus implanted into silicon in the energy range 1.7-5.0 MeV with an Eaton NV-GSD/VHE implanter

    SciTech Connect

    Rubin, L.; Shaw, W.; Jones, M.A.; Wilson, R.G.

    1996-12-31

    High energy implantation of dopant atoms is used to form buried layers of high conductivity in silicon. These layers have many potential applications, including triple wells for FLASH memory devices, buried layers for CCD devices, and damage induced gettering regions in all devices. In order to make optimum use of very high energy dopant implants, the depth and profile shape characteristics of these implants need to be determined. This paper presents the results of depth profiling by SIMS of implants of boron and phosphorus in silicon. The implants were done on an Eaton NV-GSD/VHE mechanically scanned implanter with energies of 1.7-3.0 MeV for boron and 3-5 MeV for phosphorus, doses of 1 {times} 10{sup 13}/cm{sup 2} to 1 {times} 10{sup 15}/cm{sup 2}, and tilt/twist orientations of 0{degrees}/0{degrees}, 5.2{degrees}/16.7{degrees}, and 7{degrees}/27{degrees}. The four central moments of the depth distributions, as well as the peak depth have been calculated for each of the profiles. The projected ranges of all these implants are underestimated by TRIM92 calculations.

  12. Wild-type minimal inhibitory concentration distributions in bacteria of animal origin in Argentina.

    PubMed

    Pantozzi, Florencia L; Ibar, Mariela P; Nievas, Victorio F; Vigo, Germán B; Moredo, Fabiana A; Giacoboni, Gabriela I

    2014-01-01

    The aim of this study was to determine the antimicrobial resistance profiles of indicator bacteria isolated from domestic animal feces. Minimal inhibitory concentration (MIC) was determined by agar dilution. Interpretative criteria on the basis of wild-type MIC distributions and epidemiological cutoff values (ECOFF or ECV) were used according to the 'European Committee on Antimicrobial Susceptibility Testing' (EUCAST) data. Results from 237 isolates of Escherichia coli showed reduced susceptibility for ampicillin, streptomycin and tetracycline, the antimicrobials commonly used in intensive breeding of pigs and hens. Regarding all the species of the genus Enterococcus spp., there are only ECOFF or ECV for vancomycin. Of the 173 Enterococcus spp. isolated, only one showed reduced susceptibility to vancomycin and was classified as 'non-wild-type' (NWT) population. This is the first report in Argentina showing data of epidemiological cutoff values in animal bacteria. PMID:24721272

  13. On maximum likelihood estimation of the concentration parameter of von Mises-Fisher distributions.

    PubMed

    Hornik, Kurt; Grün, Bettina

    2014-01-01

    Maximum likelihood estimation of the concentration parameter of von Mises-Fisher distributions involves inverting the ratio [Formula: see text] of modified Bessel functions and computational methods are required to invert these functions using approximative or iterative algorithms. In this paper we use Amos-type bounds for [Formula: see text] to deduce sharper bounds for the inverse function, determine the approximation error of these bounds, and use these to propose a new approximation for which the error tends to zero when the inverse of [Formula: see text] is evaluated at values tending to [Formula: see text] (from the left). We show that previously introduced rational bounds for [Formula: see text] which are invertible using quadratic equations cannot be used to improve these bounds. PMID:25309045

  14. Safety Assessment of Boron Nitride as Used in Cosmetics.

    PubMed

    Fiume, Monice M; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-01-01

    The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of boron nitride which functions in cosmetics as a slip modifier (ie, it has a lubricating effect). Boron nitride is an inorganic compound with a crystalline form that can be hexagonal, spherical, or cubic; the hexagonal form is presumed to be used in cosmetics. The highest reported concentration of use of boron nitride is 25% in eye shadow formulations. Although boron nitride nanotubes are produced, boron nitride is not listed as a nanomaterial used in cosmetic formulations. The Panel reviewed available chemistry, animal data, and clinical data and concluded that this ingredient is safe in the present practices of use and concentration in cosmetic formulations. PMID:26684796

  15. Boron carbides from first principles

    NASA Astrophysics Data System (ADS)

    Betranhandy, Emmanuel; Sjakste, Jelena; Vast, Nathalie

    2009-03-01

    In this work, we focus on the understanding gained from the investigation of the physical properties of boron-carbides with theoretical methods based on density functional theory (DFT). Comparison of computed and experimental vibrational or NMR spectra has shown that the atomic structure of B4C consists in C-B-C chains linking mostly B11C icosahedra, and a few percent of B10C2 icosahedra. In particular, C-C-C chains are excluded and can not be responsible for B4C amorphization under shockwaves. In this work we find that at lower carbon concentration all models are metastable with respect to B4C plus α-boron. This could explain actual difficulties in the synthesis of clean samples. Furthermore we discuss effects of temperature and/or pressure on stabilities and properties. Finally, the idea of combining high hardness and superconductivity in the same material by doping boron-rich solids has emerged. We show results on the strength of the electron-phonon coupling constant obtained with DFT-based methods in B13C2.

  16. Concentration profiles and spatial distribution of perfluoroalkyl substances in an industrial center with condensed fluorochemical facilities.

    PubMed

    Shan, Guoqiang; Wei, Mingcui; Zhu, Lingyan; Liu, Zhengtao; Zhang, Yahui

    2014-08-15

    Jiangsu Hi-tech Fluorochemical Industry Park, China, is one of the largest fluorochemical industry centers in Asia and could be a point source of polyfluoroalkyl substances (PFASs) to the surrounding environment. Besides water, sediment and soil samples, tree leaves and bark were also collected to monitor airborne PFASs around the facilities. Perfluorooctanoic acid and short-chain perfluorocarboxylates including perfluorohexanoic acid and perfluoropentanoic acid were found predominantly in all the samples. The target ∑PFASs were distributed in the dissolved phase with a proportion of 96.5±2.9%. High concentrations of ∑PFASs (up to 12,700 ng/L in surface water) were found at sites near and within the wastewater treatment plant and the facilities. The ∑PFASs in the sediment/sludge were in the range of 3.33-324 ng/g dw. For the first time, tree samples were used for bio-monitoring airborne PFASs in the environment. The ∑PFASs in the tree leaf and bark samples were in the range of 10.0-276 and 6.76-120 ng/g dw, respectively. The spatial distribution of ∑PFASs in the tree leaves suggested that airborne PFASs could be transported from the center to the surrounding environment by prevailing wind. PMID:24867700

  17. Particle size distribution and PAH concentrations of incense smoke in a combustion chamber.

    PubMed

    Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

    2007-01-01

    The particle size distribution and the concentrations of polycyclic aromatic hydrocarbons (PAHs) in incense smoke were studied using a custom-designed combustion chamber. Among the nine types of incense investigated, the particle and the total PAH emission factors varied significantly. The average mass median aerodynamic diameter (MMAD) of the smoke aerosol was 262+/-49nm, which positively correlated to particle emission factor (mg/stick, p<0.05). Coagulation was a major mechanism that dictates the MMAD of the smoke. The total toxic equivalency (the sum of the benzo[a]pyrene equivalent concentration) of the solid-phase PAHs (S-PAHs) was over 40 times higher than that of the corresponding gas-phase PAHs, indicating that the S-PAHs in incense smoke may pose potential health risk. Experiments show that each lowered percentage of total carbon content in the raw incense helped decrease the particle emission factor by 2.6mg/g-incense, and the reduction of S-PAH emission factor ranged from 8.7 to 26% when the carbon content was lowered from 45 to 40%. PMID:17014940

  18. Microwave sintering of boron carbide

    DOEpatents

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

    1988-06-10

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

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

    USGS Publications Warehouse

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

    2006-01-01

    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.

  20. Safety assessment of boron in aquatic and terrestrial environments.

    PubMed

    Butterwick, L; de Oude, N; Raymond, K

    1989-06-01

    Boron is a naturally occurring material and is used in industrial and domestic products. Its major release into the environment is through weathering processes and wastewater discharge. Boron is an essential nutrient for plants, but can above certain concentrations be toxic to aquatic and terrestrial organisms. This paper assesses the ecotoxicology and environmental safety of boron. It draws together the data for toxicological effects of boron and compares these with environmental concentrations of boron, measured in Europe and the U.S.A. Generally, environmental concentrations of boron found in surface water are below levels identified as toxic to aquatic organisms. Concentrations high enough to produce toxic effects in laboratory tests are found in areas where weathering of boron-rich formations and deposits occurs, such as in the southwestern United States. However, reproducing populations of the most sensitive species, rainbow trout, have been observed in surface waters in these regions, indicating no cause for concern. The prime concern for effects on terrestrial plants centers on the use of irrigation water with elevated levels of boron. At present, there is no evidence of widespread damage to crops resulting from this practice. In some areas, wastewater is used for irrigation and crops grown under these conditions are generally confined to those relatively insensitive to boron toxicity. Good irrigation practices will be necessary, however, in arid regions with high evapotranspiration rates and care will be needed when using wastewater, particularly in areas with naturally high boron levels. It is not anticipated that there will be any significant increase in the discharge of boron to the environment in the foreseeable future. The use of boron-containing products is expected to increase, but glass will remain the dominant market and the use of boron in detergents in Europe is expected to decrease due to the introduction of bleach activators and liquid detergents. There is a possibility that perborate may be used in detergents in the U.S.A.; however, the estimated increase in boron concentrations is likely to be environmentally insignificant. PMID:2743923

  1. Parameterization of Buoyancy Effects in Generic PWR Boron Dilution Scenarios

    SciTech Connect

    Galindo-Garcia, Ivan F.; Cotton, Mark A.; Axcell, Brian P.

    2006-07-01

    A computational investigation is undertaken into the role of buoyancy in a PWR boron dilution transient following a postulated Small Break Loss of Coolant Accident (SB-LOCA). In the scenario envisaged there is flow of de-borated and relatively high temperature water from a single cold leg into the downcomer; flow rates are typical of natural circulation conditions. The study focuses upon the development of boron concentration distributions in the downcomer and adopts a 3D-unsteady formulation of the mean flow equations in combination with the standard high-Reynolds-number k-{epsilon} turbulence model. It is found that the Richardson number (Ri = Gr/Re{sup 2}) is the most important group parameterizing the course of a concentration transient. At Ri values characterizing a 'baseline' scenario the results indicate that there is a stable, circumferentially-uniform, descent through the downcomer of a stratified region of low-borated fluid. Qualitatively the same behaviour is found at higher Richardson number, although at Ri values of approximately one-fifth the baseline level there is evidence of large-scale mixing and a consequent absence of concentration stratification. (authors)

  2. Iron concentrations and distributions in the parkinsonian substantia nigra of aged and young primate models

    NASA Astrophysics Data System (ADS)

    Ren, M. Q.; Xie, J. P.; Wang, X. S.; Ong, W. Y.; Leong, S. K.; Watt, F.

    2001-07-01

    Parkinson's disease (PD) is a progressive neuronal degenerative brain disease of the elderly, and is caused by the selective degeneration of neurons in the substantia nigra (SN) region of the brain, resulting in a reduced production of the neurotransmitter dopamine. Iron has been linked to dopaminergic cell death in Parkinson's disease because of its potential to promote free radicals, leading to oxidative stress. The present study is aimed at using the techniques of nuclear microscopy to elucidate the iron concentrations and distributions in the SN of both young and old monkeys following unilateral 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioning. A group of three old monkeys (older than 7 years) and a group of three young monkeys (younger than 7 years) were unilaterally MPTP-lesioned (right side) to induce parkinsonism and sacrificed after 35 days. The left side SN was used as a control. This time interval was chosen to correspond to an average 50% loss of dopamine producing cells in the lesioned right side SN. We have observed a significant difference in iron concentrations between the SNs of the young and old monkeys (increasing from an average of 233 to 1092 parts per million dry weight). When comparing the lesioned and non-lesioned SNs of the same animal, we found no significant difference in iron levels for each young monkey. However we have found a slight increase in iron (approximately 10%) between the lesioned SN and control SN for old monkeys. We have also observed that in the SN of younger primates, there is a weak anti-correlation in the SN iron levels with the neuron distribution. In the older monkeys, however, we have observed a proliferation of iron-rich granules, which appear to be more strongly anti-correlated with the distribution of neurons. The iron-cell anti-correlation occurs both in the control as well as the lesioned SN. Our results suggest that iron, particularly in the form of iron-rich deposits, accumulates in specific sites in the SN with age. Since Parkinson's disease mainly occurs in the elderly, this may implicate iron as a factor in dopaminergic cell death through iron-catalysed free radical production.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  4. Distributions of median nutrient and chlorophyll concentrations across the Red River Basin, USA.

    PubMed

    Longing, D; Haggard, B E

    2010-01-01

    Acquisition and compilation of water-quality data for an 11-yr time period (1996-2006) from 589 stream and river stations were conducted to support nutrient criteria development for the multistate Red River Basin shared by Arkansas, Louisiana, New Mexico, Oklahoma, and Texas. Ten water-quality parameters were collected from six data sources (USGS, Arkansas Department of Environmental Quality, Louisiana Department of Environmental Quality, Oklahoma Conservation Commission, Oklahoma Water Resources Board, and Texas Commission on Environmental Quality), and an additional 13 parameters were acquired from at least one source. Median concentrations of water-quality parameters were calculated at each individual station and frequency distributions (minimum, 10th, 25th, 50th, 75th, 90th percentiles, and maximum) of the median concentrations were calculated. Across the Red River Basin, median values for total nitrogen (TN), total phosphorus (TP), and sestonic chlorophyll-a (chl-a) ranged from < 0.02 to 20.2 mg L(-1), < 0.01 to 6.66 mg L(-1), and 0.10 to 262 microg L(-1), respectively. Overall, the 25th percentiles of TN data specific to the Red River Basin were generally similar to the USEPA-recommended ecoregion nutrient criteria of 0.31 to 0.88 mg L(-1), whereas median TP and chl-a data specific to the Red River Basin showed 25th percentiles higher than the USEPA-recommended criteria (0.010-0.067 mg TP L(-1); 0.93-3.00 microg chl-a L(-1)). The unique location of the Red River Basin in the south-central United States places it near the boundaries of several aggregate ecoregions; therefore, the development of ecoregion nutrient criteria likely requires using data specific to the Red River Basin, as shown in these analyses. This study provided basin-specific frequency distribution of median concentrations of water-quality parameters as the first step to support states in developing nutrient criteria to protect designated uses in the multijurisdictional Red River Basin. PMID:21284293

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

    SciTech Connect

    Pendleton, G.W.; Whitworth, M.R.; Olsen, G.H.

    1995-08-01

    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.

  6. Estimating the spatial distribution of PM2.5 concentration by integrating geographic data and field measurements

    NASA Astrophysics Data System (ADS)

    Zhai, L.; Sang, H.; Zhang, J.; An, F.

    2015-06-01

    Air quality directly affects the health and living of human beings, and it receives wide concern of public and attaches great important of governments at all levels. The estimation of the concentration distribution of PM2.5 and the analysis of its impacting factors is significant for understanding the spatial distribution regularity and further for decision supporting of governments. In this study, multiple sources of remote sensing and GIS data are utilized to estimate the spatial distribution of PM2.5 concentration in Shijiazhuang, China, by utilizing multivariate linear regression modelling, and integrating year average values of PM2.5 collected from local environment observing stations. Two major sources of PM2.5 are collected, including dust surfaces and industrial polluting sources. The area attribute of dust surfaces and point attribute of industrial polluting enterprises are extracted from high resolution remote sensing images and GIS data in 2013. 30m land cover products, annual average PM2.5 concentration values from the 8 environment monitoring stations, annual mean MODIS AOD data, traffic and DEM data are utilized in the study for regression modeling analysis. The multivariate regression analysis model is applied to estimate the spatial distribution of PM2.5 concentration. There is an upward trend of the spatial distribution of PM2.5 concentration gradually from west to east, of which the highest concentration appears in the municipal district and its surrounding areas. The spatial distribution pattern relatively fit the reality.

  7. Effects of Boron Doping on the Properties of Ultrananocrystalline Diamond Films

    NASA Astrophysics Data System (ADS)

    Yuan, Wen-Xiang; WU, Q. X.; Luo, Z. K.; Wu, H. S.

    2014-04-01

    Boron-doped ultrananocrystalline diamond (UNCD) films were fabricated on silicon substrates by microwave plasma chemical vapor deposition. UNCD films containing different concentrations of boron were prepared by using trimethylboron (B(CH3)3, TMB) as boron doping source and varying the amount of boron in the gas mixture from 0 ppm to 1000 ppm. The effects of boron doping on morphology, lattice parameter, phase composition, crystal size, and residual stress of UNCD films were investigated. No obvious change of the morphology was observed on doping with boron, and all the films had the UNCD crystal grains. Boron doping enhanced (111) growth. The preferred growth direction of the UNCD films was . Residual tensile stress was present in all the films, and increased with increasing the amount of boron in the gas mixture.

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

    NASA Astrophysics Data System (ADS)

    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

    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 μm) 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 μg m-3 (0.42-1.19 μg 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 μm, 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 μm 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.

  9. Appraisal of SIMS applicability to boron studies in plants.

    PubMed

    Dérue, Cedric; Gibouin, David; Verdus, Marie-Claire; Lefebvre, Fabrice; Demarty, Maurice; Ripoll, Camille; Thellier, Michel

    2002-07-15

    In the search for a new methodological approach applicable to the determination of the still poorly known primary role of boron in plant physiology, we have undertaken to appraise the potential of the SIMS method for the analytical imaging of the boron isotopes, (10)B and (11)B, at physiological concentrations in plants. With our own, CAMECA IMS4F SIMS ion analyser, and using O(2)(+) as primary ions for the detection of B(+) (plus (12)C(+) and (40)Ca(+)) secondary ions, we have been able to map quantitatively the two boron isotopes in control and boron-enriched plants, to evaluate boron concentrations at the level of individual cells and to determine boron isotopic ratios. This provides the opportunity to carry out the simultaneous labeling and imaging of boron, using enrichment with the stable isotopes, (10)B and (11)B. The method has also the potential for the simultaneous, quantitative detection of the boron isotopes and of the borate-binding sites in plant cells. PMID:12203710

  10. Three-dimensional structural control and analysis of hexagonal boron nitride nanosheets assembly in nanocomposite films induced by electric field concentration

    NASA Astrophysics Data System (ADS)

    Fujihara, Takeshi; Cho, Hong-Baek; Kanno, Masanao; Nakayama, Tadachika; Suzuki, Tsuneo; Jiang, Weihua; Suematsu, Hisayuki; Niihara, Koichi

    2014-02-01

    Fabrication and controlled localization of BN nanosheets assemblies were performed in polymer-based nanocomposite films under application of DC electric field switching. The localization of BN nanosheets with linearly assembled structure were modulated by applying a Si-mold electrode with micro-dimensional protrusions on the surface during electric field inducement. The established assembly of BN nanosheets, incorporated in the composite was analyzed three-dimensionally using X-ray computed tomography. The structural variation of linear assembles of BN nanosheets (LABNs) were modulated from filament-like to bridge-like structure by applying switching DC electric field whose effect was further intensified induced by electric field concentration. The nanocomposite films with localized LABNs can be potentially applied for efficient heat dissipation from local heat source, such as modern electronic, optoelectronic, photonic devices, and systems in semiconductor industry.

  11. Local impedance imaging of boron-doped polycrystalline diamond thin films

    SciTech Connect

    Zieliński, A.; Ryl, J.; Burczyk, L.; Darowicki, K.

    2014-09-29

    Local impedance imaging (LII) was used to visualise surficial deviations of AC impedances in polycrystalline boron-doped diamond (BDD). The BDD thin film electrodes were deposited onto the highly doped silicon substrates via microwave plasma-enhanced CVD. The studied boron dopant concentrations, controlled by the [B]/[C] ratio in plasma, ranged from 1 × 10{sup 16} to 2 × 10{sup 21} atoms cm{sup −3}. The BDD films displayed microcrystalline structure, while the average size of crystallites decreased from 1 to 0.7 μm with increasing [B]/[C] ratios. The application of LII enabled a direct and high-resolution investigation of local distribution of impedance characteristics within the individual grains of BDD. Such an approach resulted in greater understanding of the microstructural control of properties at the grain level. We propose that the obtained surficial variation of impedance is correlated to the areas of high conductance which have been observed at the grain boundaries by using LII. We also postulate that the origin of high conductivity is due to either preferential boron accumulation, the presence of defects, or sp{sup 2} regions in the intragrain regions. The impedance modulus recorded by LII was in full agreement with the bulk impedance measurements. Both variables showed a decreasing trend with increasing [B]/[C] ratios, which is consistent with higher boron incorporation into BDD film.

  12. Field and laboratory assessment of emergent macrophytes exposed to boron

    SciTech Connect

    Powell, R.L.; Kimerle, R.A.; Coyle, J.T.; Best, G.R.

    1995-12-31

    A risk assessment, which focused on vegetation, was conducted in response to concerns about the potential impact of boron-contaminated water in southeastern US wetlands. This assessment consisted of both field and laboratory components to determine what, if any, impact boron has to emergent macrophytes. The extensive field investigation consisted of collecting samples of surface water, sediments, and vegetation from the wetland and select reference sites. Concentrations of boron in all three media exceeded background levels. Concentrations were highest near the source but decreased to background levels near the outer perimeter of the wetland. The wetland could be divided into several distinct ecological zones, with each zone comprised of a wide variety of woody and herbaceous species. Visual signs of stress were observed for some of the vegetation, however, a correlation between tissue boron concentrations and the plant`s appearance was not demonstrated for all species. A laboratory bioassay, for emergent aquatic macrophytes, was developed and used to establish a link between the presence of boron and it`s potential effects on select species. Results from the bioassay confirmed a wide range of tolerance of emergent macrophytes to boron, based on dry weight and chlorophyll concentration. It can be concluded that boron can cause some detrimental impact to emergent macrophytes under laboratory conditions. The impact, however, varies with species and does not necessarily mimic the field. Additional research is needed to standardize both field and laboratory methods for assessing chemical impacts to emergent macrophytes.

  13. Influence Of Low Boron Core Design On PWR Transient Behavior

    SciTech Connect

    Aleksandrov Papukchiev, Angel; Yubo Liu; Schaefer, Anselm

    2006-07-01

    In conventional pressurized water reactor (PWR) designs, the concentration of boron in primary coolant is limited by the requirement of having a negative moderator density coefficient. As high boron concentrations have significant impact on reactivity feedback properties, design changes to reduce boron concentration in the reactor coolant are of general interest in view of improving PWR inherent safety. In the framework of an investigation into the feasibility of low boron design, a PWR core configuration based on fuel with higher gadolinium (Gd) content has been developed which permits to reduce the natural boron concentration at begin of cycle (BOC) by approx. 50% compared to current German PWR technology. For the assessment of the potential safety advantages, a Loss-of-Feedwater Anticipated Transient Without Scram (ATWS LOFW) has been simulated with the system code ATHLET for two PWR core designs: a low boron design and a standard core design. The most significant difference in the transient performance of both designs is the total primary fluid mass released through the pressurizer (PRZ) valves. It is reduced by a factor of four for the low boron reactor, indicating its improved density reactivity feedback. (authors)

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

    NASA Astrophysics Data System (ADS)

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

    2003-05-01

    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.

  15. Boron Enrichment in Martian Clay

    PubMed Central

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    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

  16. Boron enrichment in martian clay.

    PubMed

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. Boron and strontium isotope ratios and major/trace elements concentrations in tea leaves at four major tea growing gardens in Taiwan.

    PubMed

    Chang, Cheng-Ta; You, Chen-Feng; Aggarwal, Suresh Kumar; Chung, Chuan-Hsiung; Chao, Hung-Chun; Liu, Hou-Chun

    2016-06-01

    Isotopic compositions of B and Sr in rocks and sediments can be used as tracers for plant provincial sources. This study aims to test whether tea leaf origin can be discriminated using (10)B/(11)B and Sr isotopic composition data, along with concentrations of major/trace elements, in tea specimens collected from major plantation gardens in Taiwan. The tea leaves were digested by microwave and analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The data showed significant variations in (87)Sr/(86)Sr ratios (from 0.70482 to 0.71462), which reflect changes in soil, groundwater or irrigation conditions. The most radiogenic tea leaves were found at the Taitung garden and the least radiogenic ones were from the Hualien garden. The δ (11)B was found to change appreciably (δ (11)B = 0.38-23.73 ‰) which could be due to fertilizers. The maximum δ (11)B was also observed in tea samples from the Hualien garden. Principal component analysis combining (87)Sr/(86)Sr, δ (11)B and major/trace elements results successfully discriminated different sources of major tea gardens in Taiwan, except the Hualien gardens, and this may be due to rather complicated local geological settings. PMID:26254888

  19. Column chromatographic boron isotope separation at 5 and 17 MPa with diluted boric acid solution.

    PubMed

    Musashi, Masaaki; Oi, Takao; Matsuo, Motoyuki; Nomura, Masao

    2008-08-01

    Boron isotopic fractionation factor (S) between boron taken up in strongly basic anion exchange resin and boron in aqueous solution was determined by breakthrough column chromatography at 5 and 17 MPa at 25 degrees C, using 0.1 mM boric acid solution as feed solution. The S values obtained were 1.018 and 1.012, respectively, which were smaller than the value reported by using the same chromatographic method at the atmospheric pressure at 25 degrees C with the boron concentration of 10mM, but were larger than the values under the same condition with much higher concentration of 100 and 501 mM. Calculations based on the theory of isotope distribution between two phases estimated that 21% (5 MPa) and 47% (17 MPa) of boron taken up in the resin phase was in the three-coordinated B(OH)(3)-form, instead of in the four-coordinated B(OH)(4)-form, at high pressures even with a very diluted boric acid solution. We discussed the present results by introducing (1) hydration and (2) a partial molar volume difference between isotopic molecules. Borate may have been partially dehydrated upon transfer from the solution phase to the resin phase at high pressures, which resulted in smaller S values compared with those at the atmospheric pressure. Instead, it may be possible that the difference in the isotopic partial molar volume difference between B(OH)(3) and B(OH)(4)(-) caused the S value to decrease with increasing pressure. PMID:18585727

  20. Selenium concentration in the milk of breast-feeding mothers and its geographic distribution.

    PubMed Central

    Zachara, B A; Pilecki, A

    2000-01-01

    A total of 905 human milk samples collected in all provinces of Poland, between 12 and 75 days of lactation, were analyzed for selenium concentration. The distribution of Se levels in milk between the provinces was narrow and varied from 8.81 to 11.58 ng/mL, with the mean value (+/- SD) of 10.24 +/- 2.82 ng/mL. The regions with lower levels of Se were in the central and eastern part of Poland; the areas with higher values were in the northern, western, and southern parts of Poland. No significant correlations were found between Se levels in milk and the age of lactating mothers or between Se levels and the postpartum period. The calculated daily Se intakes by breast-fed infants varied from 6.46 to 8.50 microg/day, with the mean value of 7.52 microg/day. This amount does not meet the recommended dietary allowances for infants between 0 and 6 months of age. Based on Se levels in human milk, we present a selenium map of Poland. PMID:11102294

  1. Sensitivity of mineral dust concentrations to the model size distribution accuracy

    NASA Astrophysics Data System (ADS)

    Menut, Laurent; Forêt, Gilles; Bergametti, Gilles

    2007-05-01

    Evaluating the impacts of atmospheric dust on marine ecosystems and climate requires the use of three-dimensional transport models including a size-resolved bins scheme to describe the evolution of the particle size distribution. Recently, Forêt et al. (2006) proposed an alternative size bins scheme to better account for the physical size-dependent processes such as dry deposition. This paper evaluates the benefit of using this new bin scheme in three-dimensional transport models. This is achieved by performing a one-and-a-half month simulation with the CHIMERE-DUST model forced by the Mesoscale Model, Version 5 (MM5)/National Center for Environmental Prediction (NCEP) analysis fields, for an area covering the northern Atlantic Sea and the western Africa. Compared to a reference run performed using a large number of size bins (40), our results show that the size bins scheme proposed by Forêt et al. (2006) reduces at least by a factor of 2 the numerical errors on the simulated concentrations compared to the classical isolog bins scheme for the same number of size bins. However, with this new bins scheme requiring to define the bins according to a dry deposition velocity corresponding to a given friction velocity, we examine the errors associated to this constraint.

  2. Boron aluminum composite structures

    NASA Technical Reports Server (NTRS)

    Jackson, R. E.

    1972-01-01

    Design, analysis and fabrication techniques have been developed for boron-aluminum composite structure technology and were compared with those of conventional metal structure technology to evaluate relative performance.

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

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

    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 × 10 7 n/cm 2 s. Elemental sensitivity for boron was calibrated from the prompt gamma-ray spectra of boric acid samples containing 2-45 μg 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.

  4. Direct current sputtering of boron from boron/coron mixtures

    DOEpatents

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

    1994-01-01

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

  5. Preparation and properties of boron thin films

    SciTech Connect

    Kamimura, Kiichi; Ohkubo, Miyako; Shinomiya, Toshio

    1997-10-01

    Boron thin films were prepared by plasma assisted chemical vapor deposition. The source gas was boron trichloride (BCl{sub 3}). Ring patterns of transmission electron beam diffraction indicated that films were polycrystalline {alpha}-rhombohedral boron. Optical absorption edge was estimated from absorption spectrum. The absorption edge was about 1.05 eV for the films deposited at 700{degrees}C and was increased to about 1.4 eV as the deposition temperature increased to higher than 800{degrees}C. The Hall mobility was 10{sup -4}-10{sup -1} cm{sup 2}/Vs and the carrier concentration was 10{sup 16}-10{sup 18} cm{sup -3}. All films showed p-type conduction. The piezoresistive gauge factor was about 10.

  6. Boron-Based Drug Design.

    PubMed

    Ban, Hyun Seung; Nakamura, Hiroyuki

    2015-06-01

    The use of the element boron, which is not generally observed in a living body, possesses a high potential for the discovery of new biological activity in pharmaceutical drug design. In this account, we describe our recent developments in boron-based drug design, including boronic acid containing protein tyrosine kinase inhibitors, proteasome inhibitors, and tubulin polymerization inhibitors, and ortho-carborane-containing proteasome activators, hypoxia-inducible factor 1 inhibitors, and topoisomerase inhibitors. Furthermore, we applied a closo-dodecaborate as a water-soluble moiety as well as a boron-10 source for the design of boron carriers in boron neutron capture therapy, such as boronated porphyrins and boron lipids for a liposomal boron delivery system. PMID:25800654

  7. Boron nitride composites

    DOEpatents

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

    2016-02-16

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

  8. Enhanced surface hardness by boron implantation in Nitinol alloy.

    PubMed

    Lee, D H; Park, B; Saxena, A; Serene, T P

    1996-10-01

    Boron implantation into Nitinol alloy has a potential for developing improved Nitinol root canal instruments with excellent cutting properties, without affecting their superelastic bulk-mechanical properties. The surface hardness of nickel-titanium (NiTi) alloy, also known as "Nitinol" (50 atm% nickel+50 atm% titanium), has been improved by ion-beam surface modification. With an implantation dose of 4.8 x 10(17) boron/cm2, a high concentration of boron (30 atm%) is incorporated into NiTi alloy by 110 keV boron ions at room temperature (25 degrees C). Boron-implanted and unimplanted (pure) Nitinol alloys show surface hardness of 7.6 +/- 0.2 and 3.2 +/- 0.2 GPa, respectively, at the nanoindentation depth of 0.05 micron. The ion-beam-modified NiTi alloy exceeds the surface hardness of stainless steel. PMID:9198443

  9. Boron absorption imaging in rat lung colon adenocarcinoma metastases

    NASA Astrophysics Data System (ADS)

    Altieri, S.; Bortolussi, S.; Bruschi, P.; Fossati, F.; Vittor, K.; Nano, R.; Facoetti, A.; Chiari, P.; Bakeine, J.; Clerici, A.; Ferrari, C.; Salvucci, O.

    2006-05-01

    Given the encouraging results from our previous work on the clinical application of BNCT on non-resectable, chemotherapy resistant liver metastases, we explore the possibility to extend our technique to lung metastases. A fundamental requirement for BNCT is achieving higher 10B concentrations in the metastases compared to those in healthy tissue. For this reason we developed a rat model with lung metastases in order to study the temporal distribution of 10B concentration in tissues and tumoral cells. Rats with induced lung metastases from colon adenocarcinoma were sacrificed two hours after intraperitoneal Boronphenylalanine infusion. The lungs were harvested, frozen in liquid nitrogen and subsequently histological sections underwent neutron autoradiography in the nuclear reactor Triga Mark II, University of Pavia. Our findings demonstrate higher Boron uptake in tumoral nodules compared to healthy lung parenchyma 2 hours after Boronphenylalanine infusion.

  10. Computational Studies of Physical Properties of Boron Carbide

    SciTech Connect

    Lizhi Ouyang

    2011-09-30

    The overall goal is to provide valuable insight in to the mechanisms and processes that could lead to better engineering the widely used boron carbide which could play an important role in current plight towards greener energy. Carbon distribution in boron carbide, which has been difficult to retrieve from experimental methods, is critical to our understanding of its structure-properties relation. For modeling disorders in boron carbide, we implemented a first principles method based on supercell approach within our G(P,T) package. The supercell approach was applied to boron carbide to determine its carbon distribution. Our results reveal that carbon prefers to occupy the end sites of the 3-atom chain in boron carbide and further carbon atoms will distribute mainly on the equatorial sites with a small percentage on the 3-atom chains and the apex sites. Supercell approach was also applied to study mechanical properties of boron carbide under uniaxial load. We found that uniaxial load can lead to amorphization. Other physical properties of boron carbide were calculated using the G(P,T) package.

  11. Quantitative cross-sectional measurement of solid concentration distribution in slurries using a wire-mesh sensor

    NASA Astrophysics Data System (ADS)

    Nunes dos Santos, Eduardo; Schleicher, Eckhard; Reinecke, Sebastian; Hampel, Uwe; Da Silva, Marco Jose

    2016-01-01

    Wire-mesh sensors have so far been widely applied in gas-liquid flows where resistance or capacitance distributions are measured and converted into gas or liquid holdup distributions. In this work we report on the qualification of the wire-mesh imaging technique for the measurement of cross-sectional solid concentrations in solid-liquid mixtures. As the dielectric constants of solid particles are different from those of gas, water or oil in the flow, measuring this property can be used as an indication of solid distribution. Experiments were performed in a stirred tank of 100 mm diameter equipped with a capacitance wire-mesh sensor. The wire-mesh sensor was operated at an acquisition speed of 4000 frames per second and has a spatial resolution of 6.25 mm. As solids we used silica sand particles (diameter ~250 μm) which were suspended in water in a volume concentration range of 1% to 35% to form slurries. By varying the stirring speed, different solid concentration distributions were produced and investigated. In order to convert the measured relative permittivity distribution into a solid concentration distribution, an empirical approach was employed.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Reconstruction of national distribution of indoor radon concentration in Russia using results of regional indoor radon measurement programs.

    PubMed

    Yarmoshenko, I; Malinovsky, G; Vasilyev, A; Zhukovsky, M

    2015-12-01

    The aim of the paper is a reconstruction of the national distribution and estimation of the arithmetic average indoor radon concentration in Russia using the data of official annual 4-DOZ reports. Annual 4-DOZ reports summarize results of radiation measurements in 83 regions of Russian Federation. Information on more than 400,000 indoor radon measurements includes the average indoor radon isotopes equilibrium equivalent concentration (EEC) and number of measurements by regions and by three main types of houses: wooden, one-storey non-wooden, and multi-storey non-wooden houses. To reconstruct the national distribution, all-Russian model sample was generated by integration of sub-samples created using the results of each annual regional program of indoor radon measurements in each type of buildings. According to indoor radon concentration distribution reconstruction, all-Russian average indoor radon concentration is 48 Bq/m(3). Average indoor radon concentration by region ranges from 12 to 207 Bq/m(3). The 95-th percentile of the distribution is reached at indoor radon concentration 160 Bq/m(3). PMID:26313426

  14. Boron removal by electrocoagulation and recovery.

    PubMed

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

    2014-03-15

    This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water. PMID:24412846

  15. Concentration, Size Distribution, and Infectivity of Airborne Particles Carrying Swine Viruses

    PubMed Central

    Alonso, Carmen; Raynor, Peter C.; Davies, Peter R.; Torremorell, Montserrat

    2015-01-01

    When pathogens become airborne, they travel associated with particles of different size and composition. Particle size determines the distance across which pathogens can be transported, as well as the site of deposition and the survivability of the pathogen. Despite the importance of this information, the size distribution of particles bearing viruses emitted by infectious animals remains unknown. In this study we characterized the concentration and size distribution of inhalable particles that transport influenza A virus (IAV), porcine reproductive and respiratory syndrome virus (PRRSV), and porcine epidemic diarrhea virus (PEDV) generated by acutely infected pigs and assessed virus viability for each particle size range. Aerosols from experimentally infected pigs were sampled for 24 days using an Andersen cascade impactor able to separate particles by size (ranging from 0.4 to 10 micrometer (μm) in diameter). Air samples collected for the first 9, 20 and the last 3 days of the study were analyzed for IAV, PRRSV and PEDV, respectively, using quantitative reverse transcription polymerase chain reaction (RT-PCR) and quantified as geometric mean copies/m3 within each size range. IAV was detected in all particle size ranges in quantities ranging from 5.5x102 (in particles ranging from 1.1 to 2.1μm) to 4.3x105 RNA copies/m3 in the largest particles (9.0–10.0μm). PRRSV was detected in all size ranges except particles between 0.7 and 2.1μm in quantities ranging from 6x102 (0.4–0.7μm) to 5.1x104 RNA copies/m3 (9.0–10.0μm). PEDV, an enteric virus, was detected in all particle sizes and in higher quantities than IAV and PRRSV (p < 0.0001) ranging from 1.3x106 (0.4–0.7μm) to 3.5x108 RNA copies/m3 (9.0–10.0μm). Infectious status was demonstrated for the 3 viruses, and in the case of IAV and PRRSV, viruses were isolated from particles larger than 2.1μm. In summary, our results indicated that airborne PEDV, IAV and PRRSV can be found in a wide range of particle sizes. However, virus viability is particle size dependent. PMID:26287616

  16. Concentration, Size Distribution, and Infectivity of Airborne Particles Carrying Swine Viruses.

    PubMed

    Alonso, Carmen; Raynor, Peter C; Davies, Peter R; Torremorell, Montserrat

    2015-01-01

    When pathogens become airborne, they travel associated with particles of different size and composition. Particle size determines the distance across which pathogens can be transported, as well as the site of deposition and the survivability of the pathogen. Despite the importance of this information, the size distribution of particles bearing viruses emitted by infectious animals remains unknown. In this study we characterized the concentration and size distribution of inhalable particles that transport influenza A virus (IAV), porcine reproductive and respiratory syndrome virus (PRRSV), and porcine epidemic diarrhea virus (PEDV) generated by acutely infected pigs and assessed virus viability for each particle size range. Aerosols from experimentally infected pigs were sampled for 24 days using an Andersen cascade impactor able to separate particles by size (ranging from 0.4 to 10 micrometer (μm) in diameter). Air samples collected for the first 9, 20 and the last 3 days of the study were analyzed for IAV, PRRSV and PEDV, respectively, using quantitative reverse transcription polymerase chain reaction (RT-PCR) and quantified as geometric mean copies/m(3) within each size range. IAV was detected in all particle size ranges in quantities ranging from 5.5x10(2) (in particles ranging from 1.1 to 2.1 μm) to 4.3x10(5) RNA copies/m(3) in the largest particles (9.0-10.0 μm). PRRSV was detected in all size ranges except particles between 0.7 and 2.1 μm in quantities ranging from 6x10(2) (0.4-0.7 μm) to 5.1x10(4) RNA copies/m(3) (9.0-10.0 μm). PEDV, an enteric virus, was detected in all particle sizes and in higher quantities than IAV and PRRSV (p < 0.0001) ranging from 1.3x10(6) (0.4-0.7 μm) to 3.5x10(8) RNA copies/m(3) (9.0-10.0 μm). Infectious status was demonstrated for the 3 viruses, and in the case of IAV and PRRSV, viruses were isolated from particles larger than 2.1 μm. In summary, our results indicated that airborne PEDV, IAV and PRRSV can be found in a wide range of particle sizes. However, virus viability is particle size dependent. PMID:26287616

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  18. Biodistribution of boron after intravenous 4-dihydroxyborylphenylalanine-fructose (BPA-F) infusion in meningioma and schwannoma patients: A feasibility study for boron neutron capture therapy.

    PubMed

    Kulvik, Martti; Kallio, Merja; Laakso, Juha; Vhtalo, Jyrki; Hermans, Raine; Jrviluoma, Eija; Paetau, Anders; Rasilainen, Merja; Ruokonen, Inkeri; Seppl, Matti; Jskelinen, Juha

    2015-12-01

    We studied the uptake of boron after 100 mg/kg BPA infusion in three meningioma and five schwannoma patients as a pre-BNCT feasibility study. With average tumour-to-whole blood boron concentrations of 2.5, we discuss why BNCT could, and probably should, be developed to treat severe forms of the studied tumours. However, analysing 72 tumour and 250 blood samples yielded another finding: the plasma-to-whole blood boron concentrations varied with time, suggesting that the assumed constant boron ratio of 1:1 between normal brain tissue and whole blood deserves re-assessment. PMID:26298436

  19. Boron diffusion in nanocrystalline 3C-SiC

    SciTech Connect

    Schnabel, Manuel; Weiss, Charlotte; Rachow, Thomas; Löper, Philipp; Janz, Stefan; Canino, Mariaconcetta; Summonte, Caterina; Mirabella, Salvo; Wilshaw, Peter R.

    2014-05-26

    The diffusion of boron in nanocrystalline silicon carbide (nc-SiC) films with a grain size of 4–7 nm is studied using a poly-Si boron source. Diffusion is found to be much faster than in monocrystalline SiC as it takes place within the grain boundary (GB) network. Drive-in temperatures of 900–1000°C are suitable for creating shallow boron profiles up to 100 nm deep, while 1100°C is sufficient to flood the 200 nm thick films with boron. From the resulting plateau at 1100 °C a boron segregation coefficient of 28 between nc-SiC and the Si substrate, as well as a GB boron solubility limit of 0.2 nm{sup −2} is determined. GB diffusion in the bulk of the films is Fickian and thermally activated with D{sub GB}(T)=(3.1−5.6)×10{sup 7}exp(−5.03±0.16  eV/k{sub B}T) cm{sup 2}s{sup −1}. The activation energy is interpreted in terms of a trapping mechanism at dangling bonds. Higher boron concentrations are present at the nc-SiC surface and are attributed to immobilized boron.

  20. Effect of fluorine implantation dose on boron thermal diffusion in silicon

    NASA Astrophysics Data System (ADS)

    El Mubarek, H. A. W.; Bonar, J. M.; Dilliway, G. D.; Ashburn, P.; Karunaratne, M.; Willoughby, A. F.; Wang, Y.; Hemment, P. L. F.; Price, R.; Zhang, J.; Ward, P.

    2004-10-01

    This paper investigates how the thermal diffusion of boron in silicon is influenced by a high energy fluorine implant with a dose in the range 51014-2.31015cm-2. Secondary Ion Mass Spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine profiles to establish the conditions under which thermal boron diffusion is suppressed. The (SIMS) profiles show significantly reduced boron thermal diffusion above a critical F+ dose of 0.9-1.41015cm-2. Fitting of the measured boron profiles gives suppressions of the boron thermal diffusion coefficient by factors of 1.9 and 3.7 for F + implantation doses of 1.41015 and 2.31015cm-2, respectively. The suppression of boron thermal diffusion above the critical fluorine dose correlates with the appearance of a shallow fluorine peak on the (SIMS) profile in the vicinity of the boron marker layer. This shallow fluorine peak is present in samples with and without boron marker layers, and hence it is not due to a chemical interaction between the boron and the fluorine. Analysis of the (SIMS) profiles and cross-section Transmission Electron Microscope micrographs suggests that it is due to the trapping of fluorine at vacancy-fluorine clusters, and that the suppression of the boron thermal diffusion is due to the effect of the clusters in suppressing the interstitial concentration in the vicinity of the boron profile.

  1. City breathability and its link to pollutant concentration distribution within urban-like geometries

    NASA Astrophysics Data System (ADS)

    Buccolieri, Riccardo; Sandberg, Mats; Di Sabatino, Silvana

    2010-05-01

    This paper is devoted to the study of pollutant concentration distribution within urban-like geometries. By applying efficiency concepts originally developed for indoor environments, the term ventilation is used as a measure of city "breathability". It can be applied to analyse pollutant removal within a city in operational contexts. This implies the evaluation of the bulk flow balance over the city and of the mean age of air. The influence of building packing density on flow and pollutant removal is, therefore, evaluated using those quantities. Idealized cities of regular cubical buildings were created with packing density ranging from 6.25% to 69% to represent configurations from urban sprawl to compact cities. The relative simplicity of these arrangements allowed us to apply the Computational Fluid Dynamics (CFD) flow and dispersion simulations using the standard k- ɛ turbulence model. Results show that city breathability within the urban canopy layer is strongly dependent from the building packing density. At the lower packing densities, the city responds to the wind as an agglomeration of obstacles, at larger densities (from about 44%) the city itself responds as a single obstacle. With the exception of the lowest packing density, airflow enters the array through lateral sides and leaves throughout the street top and flow out downstream. The air entering through lateral sides increases with increasing packing density. At the street top of the windward side of compact building configurations, a large upward flow is observed. This vertical transport reduces over short distance to turn into a downward flow further downstream of the building array. These findings suggest a practical way of identifying city breathability. Even though the application of these results to real scenarios require further analyses the paper illustrates a practical framework to be adopted in the assessment of the optimum neighbourhood building layout to minimize pollution levels.

  2. NMR Study of Heavily Doped SILICON:BORON

    NASA Astrophysics Data System (ADS)

    Fuller, Scott Edward

    Pulsed nuclear magnetic resonance (NMR) has been used to study the hyperfine interactions in powdered Si:B. Samples from a variety of sources were examined to confirm the generality of our results. Room temperature carrier concentrations varied from about 3.4 times 10 ^{18} to 5.1 times 10^{19} cm ^{-3}. NMR measurements were carried out on the nuclei B^{11} and Si^{29} over a temperature range from 93 K to 463 K and an applied field strength of 8.0 T and 5.5 T. The B^{11} NMR frequency shift exhibits a Curie-like temperature dependence. A strong concentration dependence to the shift was observed. Lower concentration samples showed a more rapid rise in frequency than higher concentration samples as the temperature was lowered. Shift measurements on the highest concentration sample showed a linear dependence on applied field at lower temperatures. The Si^{29} NMR frequency showed relatively no shift over the same temperature range. B^{11} NMR in cubic NaBH_4 also showed no shift, thus ruling out the probe as a source of the shift. Both the B^{11} and Si^{29} line widths increase with decreasing temperature. We attribute all of the Si^{29} temperature dependence to a distribution of paramagnetic moments localized on a small fraction of the boron sites. Part of the B ^{11} line width temperature dependence is due a similar mechanism; other parts remain unexplained. The Si^{29}^in -lattice relaxation is due to interaction with itinerant carriers and shows a Korringa enhancement ranging from 7 to 10, possibly due to disorder. The B^ {11}^in-lattice relaxation rate is not linear in temperature in the two lower concentration samples, and is presumably associated with paramagnetic fluctuations localized on the boron sites. Relaxation in the highest concentration sample is due to interaction with itinerant carriers. We suggest that the source of the paramagnetism is transitory local moments which form on every boron site with a lifetime, tau_{rm loc}, such that T_1{rm (elec)} prec tau_{rm loc} prec 1/(2Deltaomega_ {rm sep}). T_1{ rm (elec)} is the electron spin-lattice relaxation time and Deltaomega_ {rm sep} is the separation in angular frequency space between the resonance frequency of the B^0 (paramagnetic) and the B ^{-}(diamagnetic) states. The observed shift is caused by a weighted average of the local magnetic fields at the B^0 and B ^{-} sites.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  5. Terahertz-wave water concentration and distribution measurement in thin biotissue based on a novel sample preparation

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Notake, T.; Tang, M.; Nawata, K.; Ito, H.; Minamide, H.

    2011-07-01

    The measurement of water concentration and distribution in thin biotissues with terahertz (THz)-wave has been proposed. In this paper, a novel sample preparation approach was introduced to effectively preserve tissue freshness at room temperature. Excellent stability of this method was demonstrated by measuring the transmittance spectroscopy and imaging many times within a certain time. Moreover, the reliability of water volume concentration measurement with THz-wave was evaluated. Measurement results using THz-wave were in good agreement with volume concentration measurement results based on other quantitative methods. The results suggest that water concentration and distribution measurement in thin biotissues using THz-wave will be a potential modality for medical and biological diagnosis.

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

    PubMed Central

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

    1994-01-01

    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. PMID:7889886

  7. TRANSMEMBRANE PARTITIONING ON BORON AND OTHER ELEMENTS IN RAW 264.7 AND HL60 CELL CULTURES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The trace element boron is essential for all higher plants and is beneficial or established essential for several models of human nutrition. To help identify the biomolecules that require boron for function in humans, we determined whether intracellular boron is retained against a concentration grad...

  8. Investigation of the effects of soluble boron tracking on coupled CTF / NEM, LWR simulations

    SciTech Connect

    Biery, M.; Avramova, M.; Ivanov, K.

    2013-07-01

    The primary objective of this study is to evaluate the effects of introducing a boron tracking capability to the COBRA-TF / NEM code coupling. The Pennsylvania State University (PSU) versions of COBRA-TF - CTF, and Nodal Expansion Method (NEM) codes are utilized. Previous implementations of the CTF / NEM coupled code had no capability to model soluble boron feedback effects due to boron transport. This study builds upon the validation and qualification efforts of the boron tracking model implementation in CTF by modeling the boron feedback calculated by the CTF boron tracking model in NEM. The core model chosen for this study is the Purdue MOX/UO{sub 2} core model used in the 2007 OECD/NRC code benchmark study. Following the implementation of an explicit online coupling scheme and accompanying k-search routine, the newly coupled CTF / NEM code version with boron tracking is compared to prior results of the non-boron tracking CTF / NEM code version at steady-state hot full power and hot zero power conditions. It was found that the boron tracking model exhibited little influence on the hot zero power result as expected due to a smaller heat flux, which does not significantly change the moderator density and boron concentration as the moderator travels up the axial core length. Meanwhile the boron tracking model had a much greater impact on the hot full power results, predicting the critical inlet boron concentration to be 9.9 ppm below the non-boron tracking result due to greater and more rapid changes in boron concentration corresponding to the reduction in moderator density from being more rapidly heated. (authors)

  9. Process for making boron nitride using sodium cyanide and boron

    DOEpatents

    Bamberger, Carlos E.

    1990-01-01

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

  10. Two-dimensional depth-averaged model simulation of suspended sediment concentration distribution in a groyne field

    NASA Astrophysics Data System (ADS)

    Duan, Jennifer G.; Nanda, S. K.

    2006-08-01

    SummaryRiver-training structures, such as spur dikes, are effective engineered methods used to protect banks and improve aquatic habitat. This paper reports the development and application of a two-dimensional depth-averaged hydrodynamic model to simulate suspended sediment concentration distribution in a groyne field. The governing equations of flow hydrodynamic model are depth-averaged two-dimensional Reynold's averaged momentum equations and continuity equation in which the density of sediment laden-flow varies with the concentration of suspended sediment. The depth-averaged two-dimensional convection and diffusion equation was solved to obtain the depth-averaged suspended sediment concentration. The source term is the difference between suspended sediment entrainment and deposition from bed surface. One laboratory experiment was chosen to verify the simulated flow field around a groyne, and the other to verify the suspended sediment concentration distribution in a meandering channel. Then, the model utility was demonstrated in a field case study focusing on the confluence of the Kankakee and Iroquois Rivers in Illinois, United States, to simulate the distribution of suspended sediment concentration around spur dikes. Results demonstrated that the depth-averaged, two-dimensional model can approximately simulate the flow hydrodynamic field and concentration of suspended sediment. Spur dikes can be used to effectively relocate suspended sediment in alluvial channels.

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

    PubMed

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

    2007-09-01

    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

  12. Boron nitride housing cools transistors

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Boron nitride ceramic heat sink cools transistors in r-f transmitter and receiver circuits. Heat dissipated by the transistor is conducted by the boron nitride housing to the metal chassis on which it is mounted.

  13. Annealing studies of highly doped boron superlattices

    SciTech Connect

    Jackman, T. E.; Houghton, D. C.; Jackman, J. A.; Denhoff, M. W.; Kechang, S.; McCaffrey, J.; Rockett, A.

    1989-09-01

    Coevaporation of B/sub 2/ O/sub 3/ during silicon molecular-beam epitaxy at growth temperatures (/ital T//sub /ital G// ) varying from 540 to 800 /degree/C has been used to prepare superlattice structures (/ital pipi/'s) of varying boron concentration (3/times/10/sup 18/ --3/times/10/sup 20/ B cm/sup /minus/3/). The superlattices were subsequently subjected to various annealing procedures and the layers were examined by secondary ion mass spectrometry, electrochemical profiling, and cross-sectional transmission electron microscopy. A significant redistribution of boron was observed even before annealing for /ital T//sub /ital G// /gt/700 /degree/C and high boron concentrations. In addition, significant oxygen was incorporated for /ital T//sub /ital G// /le/700 /degree/C, with a growth rate of 0.5 nm s/sup /minus/1/ and a B/sub 2/ O/sub 3/ flux of 2/times/10/sup 13/ cm/sup /minus/2/ s/sup /minus/1/. After annealing, the boron diffusion coefficients were determined for the layers and found to vary significantly with /ital T//sub /ital G//.

  14. Lactational changes in concentration and distribution of ganglioside molecular species in human breast milk from Chinese mothers.

    PubMed

    Ma, Lin; Liu, Xihong; MacGibbon, Alastair K H; Rowan, Angela; McJarrow, Paul; Fong, Bertram Y

    2015-11-01

    Gangliosides play a critical role in human brain development and function. Human breast milk (HBM) is an important dietary source of gangliosides for the growing infant. In this study, ganglioside concentrations were measured in the breast milk from a cross-sectional sample of Chinese mothers over an 8-month lactation period. The average total ganglioside concentration increased from 13.1 mg/l during the first month to 20.9 mg/l by 8 months of lactation. The average concentration during the typically solely breast-feeding period of 1‒6 months was 18.9 mg/l. This is the first study to report the relative distribution of the individual ganglioside molecular species through lactation for any population group. The ganglioside molecular species are made up of different fatty acid moieties that influence the physical properties of these gangliosides, and hence affect their function. The GM(3) molecular species containing long-chain acyl fatty acids had the most prominent changes, increasing in both concentration and relative distribution. The equivalent long-chain acyl fatty acid GD(3) molecular species typically decreased in concentration and relative distribution. The lactational trends for both concentration and relative distribution for the very long-chain acyl fatty acid molecular species were more varied. The major GM(3) and GD(3) molecular species during lactation were d40:1 and d42:1, respectively. An understanding of ganglioside molecular species distribution in HBM is essential for accurate application of mass spectrometry methods for ganglioside quantification. PMID:26404454

  15. Distribution of Particle and Gas Concentrations in Swine Gestation Confined Animal Feeding Operations

    PubMed Central

    Anthony, T. Renée; Taylor, Craig; Altmaier, Ralph; Anderson, Kimberley; O’Shaughnessy, Patrick T

    2016-01-01

    Objectives Dust mass concentrations, temperatures, and carbon dioxide concentrations were mapped in a modern, 1048-pen swine gestation barn in winter, spring, and summer. Methods In each season, two technicians measured respirable mass concentrations with an aerosol photometer and temperatures and carbon dioxide concentrations with an indoor air quality monitor at 60 positions in the barn. Stationary photometers were also deployed to measure mass concentrations during mapping at five fixed locations. Results In winter when building ventilation rates were low (center–barn mean air velocity = 0.34 m s−1, 68 fpm) to conserve heat within the barn, mass and carbon dioxide concentrations were highest (mass geometric mean, GM = 0.50mg m−3; CO2 GM = 2060 ppm) and fairly uniform over space (mass geometric standard deviation, GSD = 1.48; CO2 GSD = 1.24). Concentrations were lowest in summer (mass GM = 0.13mg m−3; CO2 GM = 610 ppm) when ventilation rates were high (center–barn mean air velocity = 0.99 m s−1, 196 fpm) to provide cooling. Spatial gradients were greatest in spring (mass GSD = 2.11; CO2 GSD = 1.50) with low concentrations observed near the building intake, increasing to higher concentrations at the building exhaust. Conclusions Mass concentrations obtained in mapping were generally consistent with those obtained from stationary monitors. A moderately strong linear relationship (R2 = 0.60) was observed between the log of photometer-measured mass concentration and the log of carbon dioxide concentration, suggesting that carbon dioxide may be an inexpensive alternative to assessing air quality in a swine barn. These results indicate that ventilation can effectively reduce contaminant levels in addition to controlling temperature. PMID:22904211

  16. Airborne DOAS measurements in Arctic: vertical distributions of aerosol extinction coefficient and NO2 concentration

    NASA Astrophysics Data System (ADS)

    Merlaud, A.; van Roozendael, M.; Theys, N.; Fayt, C.; Hermans, C.; Quennehen, B.; Schwarzenboeck, A.; Ancellet, G.; Pommier, M.; Pelon, J.; Burkhart, J.; Stohl, A.; de Mazière, M.

    2011-09-01

    We report on airborne Differential Optical Absorption Spectroscopy (DOAS) measurements of aerosol extinction and NO2 tropospheric profiles performed off the North coast of Norway in April 2008. The DOAS instrument was installed on the Safire ATR-42 aircraft during the POLARCAT-France spring campaign and recorded scattered light spectra in near-limb geometry using a scanning telescope. We use O4 slant column measurements to derive the aerosol extinction at 360 nm. Regularization is based on the maximum a posteriori solution, for which we compare a linear and a logarithmic approach. The latter inherently constrains the solution to positive values and yields aerosol extinction profiles more consistent with independently measured size distributions. We present results from two soundings performed on 8 April 2008 above 71° N, 22° E and on 9 April 2008 above 70° N, 17.8° E. The first profile shows aerosol extinction and NO2 in the marine boundary layer with respective values of 0.04 ± 0.005 km-1 and 1.9 ± 0.3 × 109 molec cm-3. A second extinction layer of 0.01 ± 0.003 km-1 is found at 4 km altitude where the NO2 concentration is 0.32 ± 0.2 × 109 molec cm-3. During the second sounding, clouds prevent retrieval of profile parts under 3 km altitude but a layer with enhanced extinction (0.025 ± 0.005 km-1) and NO2 (1.95 ± 0.2 × 109 molec cm-3) is clearly detected at 4 km altitude. From CO and ozone in-situ measurements complemented by back-trajectories, we interpret the measurements in the free troposphere as, for the first sounding, a mix between stratospheric and polluted air from Northern Europe and for the second sounding, polluted air from Central Europe containing NO2. Considering the boundary layer measurements of the first flight, modeled source regions indicate closer sources, especially the Kola Peninsula smelters, which can explain the NO2 enhancement not correlated with a CO increase at the same altitude.

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

    PubMed

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

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18 μgB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20 min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm. PMID:26242558

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

    NASA Astrophysics Data System (ADS)

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

    2003-09-01

    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 or health risk analysis. A fully Bayesian analysis using Markov chain Monte Carlo (MCMC) simulation is used for statistical inference. The applicability of this methodology is illustrated by the analysis of a national survey of Cryptosporidium parvum concentrations, in which 93% of the observations were zero counts.

  19. Characteristics of Au Migration and Concentration Distributions in Au-Doped HgCdTe LPE Materials

    NASA Astrophysics Data System (ADS)

    Sun, Quanzhi; Yang, Jianrong; Wei, Yanfeng; Zhang, Juan; Sun, Ruiyun

    2015-08-01

    Annealing techniques and secondary ion mass spectrometry have been used to study the characteristics of Au migration and concentration distributions in HgCdTe materials grown by liquid phase epitaxy. Secondary ion mass spectrometry measurements showed that Au concentrations had obvious positive correlations with Hg-vacancy concentration and dislocation density of the materials. Au atoms migrate toward regions of high Hg-vacancy concentration or move away from these regions when the Hg-vacancy concentration decreases during annealing. The phenomenon can be explained by defect chemical equilibrium theory if Au atoms have a very large migration velocity compared with Hg vacancies. Au atoms will also migrate toward regions of high dislocation density, leading to a peak concentration in the inter-diffusion region of HgCdTe materials near the substrate. By use of an Hg and Te-rich annealing technique, different concentration distributions of both Au atoms and Hg vacancies in HgCdTe materials were obtained, indicating that Au-doped HgCdTe materials can be designed and prepared to satisfy the requirements of HgCdTe devices.

  20. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    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.

  1. Mineral of the month: boron

    USGS Publications Warehouse

    Lyday, Phyllis A.

    2005-01-01

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

  2. Boron exposure assessment using drinking water and urine in the North of Chile.

    PubMed

    Cortes, S; Reynaga-Delgado, E; Sancha, A M; Ferreccio, C

    2011-12-01

    Boron is an essential trace element for plants and humans however it is still an open question what levels of boron are actually safe for humans. This study, conducted between 2006 and 2010, measured exposure levels of boron in drinking water and urine of volunteers in Arica, an area in the North of Chile with high levels of naturally occurring boron. Samples were taken of tap and bottled water (173 and 22, respectively), as well as urine from 22 volunteers, and subsequently analyzed by inductively coupled plasma spectroscopy (ICP-OES). Boron varied in public tap water from 0.22 to 11.3mgL(-1), with a median value of 2.9mgL(-1), while concentrations of boron in bottled water varied from 0.01 to 12.2mgL(-1). Neither tap nor bottled water samples had concentrations of boron within WHO recommended limits. The concentration of boron in urine varied between 0.45 and 17.4mgL(-1), with a median of 4.28mgL(-1) and was found to be correlated with tap water sampled from the homes of the volunteers (r=0.64). Authors highly recommend that in northern Chile - where levels of boron are naturally high - that the tap and bottled water supplies be monitored in order to protect public health and that regulatory standards also be established for boron in drinking water in order to limit exposure. PMID:21978616

  3. 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...

  4. A measurement plan of gas concentration and temperature distribution reconstruction based on the tunable diode laser absorption tomography

    NASA Astrophysics Data System (ADS)

    Liu, Zhao-ran; Jin, Xing; Wang, Guang-yu; Song, Jun-ling

    2014-11-01

    Based on the tunable diode laser absorption tomography, gas concentration and temperature two-dimensional distribution reconstruction is realized using algebraic iterative reconstruction technique (ART). A measurement plan is proposed based on the beam splitting lens, and the corresponding beam arrangement is put forward. The beam splitting lenses are used in the plan to making one laser beam cross the measurement area repeatedly. Thus can raise the utilization ratio of laser beam and simplify the structure of measurement platform. A model for H2O vapor concentration and temperature distribution is assumed, and numerical simulation is utilized using two absorption transitions. The feasibility of the measurement plan is proved by the simulation experiment. The influences of initial beam angle, the number of beams and grids on the reconstructed results are analyzed numerically. A concept of phantom description method using in simulation experiments is proposed in order to getting closer to the real experiments. The phantom description method is used in the numerical simulation to evaluating concentration and temperature field reconstruction. Through this method, expected data is sampled from initial data, and reconstructed result is obtained by interpolation. The influence of random errors in projections on distribution reconstruction is also analyzed. The measurement plan can reconstruct the gas concentration and temperature distribution with a simplified measurement platform using beam splitting lenses. The feasibility of the phantom description method is also proved by the simulation experiment.

  5. The distribution and variability of simulated chlorophyll concentration over the tropical Indian Ocean from five CMIP5 models

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Feng, Lin; Yu, Weidong; Wang, Huiwu; Liu, Yanliang; Sun, Shuangwen

    2013-06-01

    Performances of 5 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) in simulating the chlorophyll concentration over the tropical Indian Ocean are evaluated. Results show that these models are able to capture the dominant spatial distribution of observed chlorophyll concentration and reproduce the maximum chlorophyll concentration over the western part of the Arabian Sea, around the tip of the Indian subcontinent, and in the southeast tropical Indian Ocean. The seasonal evolution of chlorophyll concentration over these regions is also reproduced with significant amplitude diversity among models. All of 5 models is able to simulate the interannual variability of chlorophyll concentration. The maximum interannual variation occurs at the same regions where the maximum climatological chlorophyll concentration is located. Further analysis also reveals that the Indian Ocean Dipole events have great impact on chlorophyll concentration in the tropical Indian Ocean. In the general successful simulation of chlorophyll concentration, most of the CMIP5 models present higher than normal chlorophyll concentration in the eastern equatorial Indian Ocean.

  6. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources.

    PubMed

    Mainhagu, J; Morrison, C; Brusseau, M L

    2015-01-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site. PMID:25835545

  7. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Morrison, C.; Brusseau, M. L.

    2015-06-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.

  8. Inhibition of sickling after reduction of intracellular hemoglobin concentration with an osmotic pulse: characterization of the density and hemoglobin concentration distributions.

    PubMed

    Franco, R S; Barker-Gear, R; Green, R

    1993-01-01

    Hemoglobin S polymerization is markedly dependent on intracellular hemoglobin concentration. In the studies presented here, sickle RBC were subjected to a transient osmotic stress, which induced a short period of increased membrane permeability and allowed partial efflux of Hb S. Morphological sickling of the resulting hypochromic RBC was inhibited. The response of RBC to this osmotic pulse is influenced by the presence of a polyanion, which in these experiments was either inositol hexaphosphate (IHP, 27 mM or 46 mM) or pyrophosphate (69 mM or 95 mM). The decrease in MCHC, measured manually, ranged from 3.1 +/- 1.7 (1 SD) to 6.3 +/- 2.8 g/dl, depending on the conditions used during modification. Parallel electronic analysis of RBC indices demonstrated a comparable decrease in MCHC which was due to both an increased MCV and a decreased MCH. Since the modified cell population is quite heterogeneous, cells were analyzed using discontinuous stractan gradients and/or a laser-based instrument which measures the hemoglobin concentration (HC) of individual cells. For most treatment conditions, the modified cells have a bimodal HC distribution with one peak centered at about 20 g/dL and the other peak corresponding to the unmodified cells. With the higher concentration of IHP, however, many cells had an intermediate HC. For modified RBC with a bimodal HC distribution (27 mM IHP, 69 mM PP, 95 mM PP), inhibition of morphological sickling was proportional to the change in HC and there were no subpopulations with an increased tendency to undergo sickling. However, the intermediate density cells present when RBCs were treated with the higher concentration of IHP underwent sickling at a higher oxygen partial pressure than control cells. PMID:8312575

  9. Pore-size distributions of cationic polyacrylamide hydrogels varying in initial monomer concentration and cross-linker/monomer ratio

    SciTech Connect

    Kremer, M.; Pothmann, E.; Roessler, T.; Baker, J.; Yee, A.; Blanch, H.; Prausnitz, J.M. )

    1994-05-23

    Pore-size distributions have been measured for cationic acrylamide-based hydrogels. The authors use the experimental mixed-solute-exclusion method, MSE (introduced by Kuga), to obtain the solute-exclusion curve representing the amount of imbibed liquid inside the gel inaccessible for a solute of radius r. The authors use the Brownian motion model (developed by Cassasa) to convert the size-exclusion curve into the pore-size distribution, which gives the frequency of pore radius R as a function of R. This theoretically-based interpretation of MSE data leads to the Fredholm integral equation that they solve numerically. Results are reported for a series of hydrogels containing acrylamide and 3% MAPTAC; the hydrogels differed in extent of cross-linking and/or initial concentration of monomer. Pore-size distributions shift to lower pore sizes with rising initial monomer concentration and with rising cross-linker-to-monomer ratio.

  10. A Drude model analysis of conductivity and free carriers in boron-doped diamond films and investigations of their internal stress and strain

    PubMed Central

    Manciu, Marian; Durrer, William G.; Salazar, Jessica G.; Lee, Kendall H.; Bennet, Kevin E.

    2014-01-01

    Boron-doped diamond (BDD) has seen a substantial increase in interest for use as electrode coating material for electrochemistry and studies of deep brain stimulation mechanism. In this study, we present an alternative method for determining important characteristics, including conductivity, carrier concentration, and time constant, of such material by the signature of Drude-like metallic behavior in the far-infrared (IR) spectral range. Unlike the direct determination of conductivity from the four-point probe method, using far-IR transmittance provides additional information, such as whether the incorporation of boron results in a large concentration of carriers or in inducing defects in the diamond lattice. The slightly doped to medium-doped BDD samples that were produced using chemical vapor deposition and analyzed in this work show conductivities ranging between 5.5 and 11 (Ω cm)−1. Different growth conditions demonstrate that increasing boron concentration results in an increase in the carrier concentration, with values between 7.2 × 1016 and 2.5 × 1017 carriers/cm3. Addition of boron, besides leading to a decrease in the resistivity, also resulted in a decrease in the time constant, limiting BDD conductivity. Investigations, by confocal Raman mapping, of the induced stress in the material due to interaction with the substrate or to the amount of doping are also presented and discussed. The induced tensile stress, which was distributed closer to the film-substrate interface decreased slightly with doping. PMID:25328245

  11. Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution.

    PubMed

    Schaefer, Adam M; Titcomb, Elizabeth Murdoch; Fair, Patricia A; Stavros, Hui-Chen W; Mazzoil, Marilyn; Bossart, Gregory D; Reif, John S

    2015-08-15

    Bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, FL (IRL) have tissue mercury concentrations among the highest reported worldwide. Analysis of total mercury (THg) concentrations in blood collected between 2003 and 2012 showed a significant linear decrease over time (p=0.04). Significant differences in the spatial distribution of THg in resident IRL dolphins were also observed with a general gradient in concentration from north to south. Evaluation of local biogeochemistry and accumulation of mercury in prey species is needed to better understand factors influencing the distribution of Hg in the apex predator. Analyses of temporal and spatial patterns of exposure to THg in this sentinel species may have implications for both ecosystem and public health in the region. PMID:26119626

  12. BORON TRANSPORT WITHIN AN AGRICULTURAL FIELD: UNIFORM FLOW VERSUS MOBILE-IMMOBILE MODEL SIMULATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transport of boron in soil is important to agriculture because boron concentrations in soil water are beneficial to plants only over a limited range (0.37 to 1.39 mmol L-1 for tolerant crops). Irrigation water in the San Joaquin Valley, California commonly has elevated B concentrations and soil ...

  13. EFFECT OF HIGH BORON APPLICATION ON BORON CONTENT AND GROWTH OF MELONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management options for reducing drainage water volumes on the west side of the San Joaquin Valley of California such as reuse of saline drainage water and water table control have the potential to adversely impact crop yields due to a build up in boron concentration. An earlier experiment had shown...

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

    SciTech Connect

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

    1999-06-06

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

  15. Minerals Yearbook 1989: Boron

    SciTech Connect

    Lyday, P.A.

    1990-08-01

    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.

  16. Producing boron carbide

    SciTech Connect

    Rafaniello, W.; Moore, W.G.

    1989-01-14

    A method is described for producing boron carbide. A particulate reactive mixture of a boric oxide source and a carbon source is passed through a hot zone such that substantially all of the particles of the reactive mixture are separately and individually heated at a heating rate of at least about 70/sup 0/C/second to a sufficient temperature and for a sufficient length of time to form boron carbide crystals, of which at least about 25 percent by weight are of submicron size.

  17. Hydrodynamic analysis of fully developed turbidity currents over plane beds based on self-preserving velocity and concentration distributions

    NASA Astrophysics Data System (ADS)

    Cantero-Chinchilla, Francisco Nicolás.; Dey, Subhasish; Castro-Orgaz, Oscar; Ali, Sk Zeeshan

    2015-10-01

    This paper presents a hydrodynamic analysis for the fully developed turbidity currents over a plane bed stemming from the classical three-equation model (depth-averaged fluid continuity, sediment continuity, and fluid momentum equations). The streamwise velocity and the concentration distributions preserve self-similarity characteristics and are expressed as single functions of vertical distance over the turbidity current layer. Using the experimental data of turbidity and salinity currents, the undetermined coefficients and exponents are approximated. The proposed relationships for velocity and concentration distributions exhibit self-preserving characteristics for turbidity currents. The depth-averaged velocity, momentum, and energy coefficients are thus obtained using the proposed expression for velocity law. Also, from the expressions for velocity and concentration, the turbulent diffusivity and the Reynolds shear stress distributions are deduced with the aid of the diffusion equation of sediment concentration and the Boussinesq hypothesis. The generalized equation of unsteady nonuniform turbidity current is developed by using the velocity and concentration distributions in the moments of the integral scales over the turbidity current layer. Then, the equation is applied to analyze the gradually varied turbidity currents considering closure relationships for boundary interaction and shear velocity. The streamwise variations of current depth, velocity, concentration, reduced sediment flux, and Richardson number are presented. Further, the self-accelerating and depositional characteristics of turbidity currents including the transitional feature from erosional to depositional modes are addressed. The effects of the streamwise bed slope are also accounted for in the mathematical derivations. The results obtained from the present model are compared with those from the classical model.

  18. Profiling the PM2.5 mass concentration vertical distribution in the boundary layer

    NASA Astrophysics Data System (ADS)

    Tao, Zongming; Wang, Zhenzhu; Yang, Shijun; Shan, Huihui; Ma, Xiaomin; Zhang, Hui; Zhao, Sugui; Liu, Dong; Xie, Chenbo; Wang, Yingjian

    2016-04-01

    Fine particles (PM2.5) affect human life and activities directly; the detection of PM2.5 mass concentration profile is very essential due to its practical and scientific significance (such as the quantification of air quality and its variability as well as the assessment of improving air quality forecast). But so far, it has been difficult to detect PM2.5 mass concentration profile. The proposed methodology to study the relationship between aerosol extinction coefficient and PM2.5 mass concentration is described, which indicates that the PM2.5 mass concentration profile could be retrieved by combining a charge-coupled device (CCD) side-scatter lidar with a PM2.5 sampling detector. When the relative humidity is less than 70 %, PM2.5, mass concentration is proportional to the aerosol extinction coefficient, and then the specific coefficient can be calculated. Through this specific coefficient, aerosol extinction profile is converted to PM2.5 mass concentration profile. Three cases of clean night (on 21 September 2014), pollutant night (on 17 March 2014), and heavy pollutant night (on 13 February 2015) are studied. The characteristics of PM2.5 mass concentration profile at the near-ground level during the cases of these 3 nights in the western suburb of Hefei city were discussed. The PM2.5 air pollutant concentration is comparatively large close to the surface and varies with time and altitude. The experiment results show that the CCD side-scatter lidar combined with a PM2.5 detector is an effective and new method to explore pollutant mass concentration profile at the near-ground level.

  19. Profiling the PM2.5 mass concentration vertical distribution in the boundary layer

    NASA Astrophysics Data System (ADS)

    Tao, Z.; Wang, Z.; Yang, S.; Shan, H.; Ma, X.; Zhang, H.; Zhao, S.; Liu, D.; Xie, C.; Wang, Y.

    2015-12-01

    Fine particle (PM2.5) affects human life and activities directly; the detection of PM2.5 mass concentration profile is very essential due to its practical and scientific meanings (such as, quantifying of air quality and its variability, and improving air quality forecast and assessment). But so far, it is difficult to detect PM2.5 mass concentration profile. The proposed methodology to study the relationship between aerosol extinction coefficient and PM2.5 mass concentration is described, which indicates that the PM2.5 mass concentration profile could be retrieved by combining a charge-coupled device (CCD) side-scatter lidar and a PM2.5 sampling detector. When the relative humidity is less than 70 %, PM2.5 mass concentration is proportional to aerosol extinction coefficient, and then the specific coefficient can be calculated. Using this specific coefficient, aerosol extinction profile is converted to PM2.5 mass concentration profile. Three cases of clean night (on 21 September 2014), pollutant night (on 17 March 2014), and heavy pollutant night (on 13 February 2015) are studied. The characteristic of PM2.5 mass concentration profile in near-ground during these three nights' cases in the western suburb of Hefei city was discussed. The PM2.5 air pollutant concentration is comparatively large in close surface varying with time and altitude. The experiment results show that the CCD side-scatter lidar combined with a PM2.5 detector is an effective and new method to explore pollutant mass concentration profile in near-ground.

  20. Use of boron waste as an additive in red bricks

    SciTech Connect

    Uslu, T.; Arol, A.I

    2004-07-01

    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.

  1. Geographical distribution of the annual mean radon concentrations in primary schools of Southern Serbia - application of geostatistical methods.

    PubMed

    Bossew, P; Žunić, Z S; Stojanovska, Z; Tollefsen, T; Carpentieri, C; Veselinović, N; Komatina, S; Vaupotič, J; Simović, R D; Antignani, S; Bochicchio, F

    2014-01-01

    Between 2008 and 2011 a survey of radon ((222)Rn) was performed in schools of several districts of Southern Serbia. Some results have been published previously (Žunić et al., 2010; Carpentieri et al., 2011; Žunić et al., 2013). This article concentrates on the geographical distribution of the measured Rn concentrations. Applying geostatistical methods we generate "school radon maps" of expected concentrations and of estimated probabilities that a concentration threshold is exceeded. The resulting maps show a clearly structured spatial pattern which appears related to the geological background. In particular in areas with vulcanite and granitoid rocks, elevated radon (Rn) concentrations can be expected. The "school radon map" can therefore be considered as proxy to a map of the geogenic radon potential, and allows identification of radon-prone areas, i.e. areas in which higher Rn radon concentrations can be expected for natural reasons. It must be stressed that the "radon hazard", or potential risk, estimated this way, has to be distinguished from the actual radon risk, which is a function of exposure. This in turn may require (depending on the target variable which is supposed to measure risk) considering demographic and sociological reality, i.e. population density, distribution of building styles and living habits. PMID:24231373

  2. Fracture Strength: Stress Concentration, Extreme Value Statistics, and the Fate of the Weibull Distribution

    NASA Astrophysics Data System (ADS)

    Bertalan, Zsolt; Shekhawat, Ashivni; Sethna, James P.; Zapperi, Stefano

    2014-09-01

    The statistical properties of fracture strength of brittle and quasibrittle materials are often described in terms of the Weibull distribution. However, the weakest-link hypothesis, commonly used to justify it, is expected to fail when fracture occurs after significant damage accumulation. Here we show that this implies that the Weibull distribution is unstable in a renormalization-group sense for a large class of quasibrittle materials. Our theoretical arguments are supported by numerical simulations of disordered fuse networks. We also find that for brittle materials such as ceramics, the common assumption that the strength distribution can be derived from the distribution of preexisting microcracks by using Griffith's criteria is invalid. We attribute this discrepancy to crack bridging. Our findings raise questions about the applicability of Weibull statistics to most practical cases.

  3. Boron hydride polymer coated substrates

    DOEpatents

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

    1987-01-01

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

  4. Boron hydride polymer coated substrates

    DOEpatents

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

    1986-08-27

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

  5. Boron Requirement in Cyanobacteria 1

    PubMed Central

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

    1990-01-01

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

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

    PubMed Central

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

    2013-01-01

    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. PMID:23671627

  7. A study of Monitoring and Mapping for Radon-Concentration Distribution in Gyeongju - 12201

    SciTech Connect

    Park, Chan Hee; Lee, Jung Min; Jang, So Young; Kim, Shin Jae; Moon, Joo Hyun

    2012-07-01

    Radon is one of the most important contributors to the radiation exposure in humans. This study measured the indoor radon concentrations at the 17 elementary school auditoriums that were sampled from those in the city of Gyeongju, Korea. The reason that an elementary school was selected as a measurement object is that many students and teachers stay for a long time in a day and it's easy to identify the characteristics of the auditorium building such as the essential building. The measurement shows that most of the indoor radon concentrations at the 17 elementary school auditoriums did not exceed 148 Bq/m{sup 3} that is the action level recommended by U.S. Environmental Protection Agency. This study measured the indoor radon concentrations at the elementary school auditoriums in Gyeongju. The measurements were analyzed according to the bedrock type and the time intervals per day. In this study, it was found that the indoor radon concentrations over off-duty hours were generally higher that those over on-duty hours, and the indoor radon concentration in the area whose bedrock is volcanic rock was higher than those in the area of the other types of bedrock. As mentioned above, attention has to be paid to an elementary school since many young students and teachers stay for more 6 hours a day at it. Hence, it is necessary to continuously monitor and properly manage the indoor radon concentrations in the elementary schools. (authors)

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

    DOEpatents

    Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

    1986-01-01

    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.

  9. Biodistribution of the boron carriers boronophenylalanine (BPA) and/or decahydrodecaborate (GB-10) for Boron Neutron Capture Therapy (BNCT) in an experimental model of lung metastases

    SciTech Connect

    D.W. Nigg; Various Others

    2014-06-01

    BNCT was proposed for the treatment of diffuse, non-resectable tumors in the lung. We performed boron biodistribution studies with 5 administration protocols employing the boron carriers BPA and/or GB-10 in an experimental model of disseminated lung metastases in rats. All 5 protocols were non-toxic and showed preferential tumor boron uptake versus lung. Absolute tumor boron concentration values were therapeutically useful (25–76 ppm) for 3 protocols. Dosimetric calculations indicate that BNCT at RA-3 would be potentially therapeutic without exceeding radiotolerance in the lung.

  10. [Concentration distribution of metal elements in atmospheric aerosol under different weather conditions in Qingdao Coastal Region].

    PubMed

    Chen, Xiao-Jing; Qi, Jian-Hua; Liu, Ning; Zhang, Xiang-Yu; Shen, Heng-Qing; Liu, Ming-Xu

    2014-10-01

    To know the influence of different weather conditions on the concentration of metal elements in aerosols in the coastal region, total suspended particles (TSP) samples were collected from April to May 2012, and August 2012 to March 2013 in the Qingdao coastal region, and common trace metals were analyzed by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results showed that Al, Ca, Fe, Na, K and Mg were the dominant metal elements in TSP, and the sum of the six elements accounted for 94.2% of the sum of all metals. TSP and metal elements had significant monthly variations, Fe, Al, K, Ca, Mg, Zn, Ba, Mn, Ti, Sr and Li had the highest concentration in November and January, while Be, Sc, Co, Ni and Cr showed the highest value in January. Na had the highest concentration in August, November and February, and the lowest in December. Pb had the highest concentration in January and February, and the lowest in August and December. Enrichment factors indicated that Be, Co, Al, Ca, Fe, K, Mg, Mn, Sr and Ti were mainly affected by natural sources; Li, Cr, Ni, Zn, Ba and Na were affected by natural sources and part of anthropogenic sources; Pb was mainly from anthropogenic sources. Different weather conditions had great impact on TSP and metal elements concentrations, all the measured metals had the highest concentrations in smog except Ti. Compared with the sunny day, the concentration of atmospheric particulate Ti decreased, while the other elements increased by 1 to 4 times in smog. Li, Be, Cr, Ni, Al, Fe, Mg and Mn had little variation in concentration in foggy day, and the concentration of Pb and Na increased considerably. The concentration of Co, Ca and Ti reduced obviously in fog. Except for Cr, Co and Ti, the other elements increased by 1 to 3 times in haze. Most of the elements had the minimal enrichment factors in sunny day, while the other had the maximal enrichment factor in foggy day. Enrichment factors of Ni, Zn, Ba, K, Na, Pb and Sr varied in the order of sunny day < haze day < smog day

  11. Chemistry and biology of boron.

    PubMed

    Loomis, W D; Durst, R W

    1992-04-01

    Boron is an essential nutrient for certain organisms, notably vascular plants and diatoms. Cyanobacteria require boron for formation of nitrogen-fixing heterocysts and boron may be beneficial to animals. Boron deficiency in plants produces manifold symptoms: many functions have been postulated. Deficiency symptoms first appear at growing points, within hours in root tips and within minutes or seconds in pollen tube tips, and are characterized by cell wall abnormalities. Boron-deficient tissues are brittle or fragile, while plants grown on high boron levels may have unusually flexible or resilient tissues. Borate forms cyclic diesters with appropriate diols or polyols. The most stable are formed with cis-diols on a furanoid ring. Two compounds have this structure physiologically: ribose in ribonucleotides and RNA, and apiose in the plant cell wall. Germanium can substitute for boron in carrot cell cultures. Both boron and germanium are localized primarily in the cell wall. We postulate that borate-apiofuranose ester cross-links are the auxin-sensitive acid-growth link in vascular plants, that the cyanobacterial heterocyst envelope depends on borate cross-linking of mannopyranose and/or galactopyranose residues in a polysaccharide-lipid environment, and that boron in diatoms forms ester cross-links in the polysaccharide cell wall matrix rather than boron-silicon interactions. Complexing of ribonucleotides is probably a factor in boron toxicity. PMID:1605832

  12. Boron uptake, localization, and speciation in marine brown algae.

    PubMed

    Miller, Eric P; Wu, Youxian; Carrano, Carl J

    2016-02-17

    In contrast to the generally boron-poor terrestrial environment, the concentration of boron in the marine environment is relatively high (0.4 mM) and while there has been extensive interest in its use as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the relatively depth independent, and the generally non-nutrient-like concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the ocean. Among the marine plant-like organisms the brown algae (Phaeophyta) are one of only five lineages of photosynthetic eukaryotes to have evolved complex multicellularity. Many of unusual and often unique features of brown algae are attributable to this singular evolutionary history. These adaptations are a reflection of the marine coastal environment which brown algae dominate in terms of biomass. Consequently, brown algae are of fundamental importance to oceanic ecology, geochemistry, and coastal industry. Our results indicate that boron is taken up by a facilitated diffusion mechanism against a considerable concentration gradient. Furthermore, in both Ectocarpus and Macrocystis some boron is most likely bound to cell wall constituent alginate and the photoassimilate mannitol located in sieve cells. Herein, we describe boron uptake, speciation, localization and possible biological function in two species of brown algae, Macrocystis pyrifera and Ectocarpus siliculosus. PMID:26679972

  13. Use of dissolved H2 concentrations to determine distribution of microbially catalyzed redox reactions in anoxic groundwater

    USGS Publications Warehouse

    Lovley, D.R.; Chapelle, F.H.; Woodward, J.C.

    1994-01-01

    The potential for using concentrations of dissolved H2 to determine the distribution of redox processes in anoxic groundwaters was evaluated. In pristine aquifers in which standard geochemical measurements indicated that Fe-(III) reduction, sulfate reduction, or methanogenesis was the terminal electron accepting process (TEAP), the H2 concentrations were similar to the H2 concentrations that have previously been reported for aquatic sediments with the same TEAPs. In two aquifers contaminated with petroleum products, it was impossible with standard geochemical analyses to determine which TEAPs predominated in specific locations. However, the TEAPs predicted from measurements of dissolved H2 were the same as those determined directly through measurements of microbial processes in incubated aquifer material. These results suggest that H2 concentrations may be a useful tool for analyzing the redox chemistry of nonequilibrium groundwaters.

  14. Fabrication of boron sputter targets

    DOEpatents

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

    1995-02-28

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

  15. Fabrication of boron sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1995-01-01

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

  16. Size distribution and concentration of soot generated in oil and gas-fired residential boilers under different combustion conditions

    NASA Astrophysics Data System (ADS)

    Jiménez, Santiago; Barroso, Jorge; Pina, Antonio; Ballester, Javier

    2016-05-01

    In spite of the relevance of residential heating burners in the global emission of soot particles to the atmosphere, relatively little information on their properties (concentration, size distribution) is available in the literature, and even less regarding the dependence of those properties on the operating conditions. Instead, the usual procedure to characterize those emissions is to measure the smoke opacity by several methods, among which the blackening of a paper after filtering a fixed amount of gas (Bacharach test) is predominant. In this work, the size distributions of the particles generated in the combustion of a variety of gaseous and liquid fuels in a laboratory facility equipped with commercial burners have been measured with a size classifier coupled to a particle counter in a broad range of operating conditions (air excesses), with simultaneous determination of the Bacharach index. The shape and evolution of the distribution with progressively smaller oxygen concentrations depends essentially on the state of the fuel: whereas the combustion of the gases results in monomodal distributions that 'shift' towards larger diameters, in the case of the gas-oils an ultrafine mode is always observed, and a secondary mode of coarse particle grows in relevance. In both cases, there is a strong, exponential correlation between the total mass concentration and the Bacharach opacity index, quite similar for both groups of fuels. The empirical expressions proposed may allow other researchers to at least estimate the emissions of numerous combustion facilities routinely characterized by their smoke opacities.

  17. Biaxial Compressive Strain Engineering in Graphene/Boron Nitride Heterostructures

    PubMed Central

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

    2012-01-01

    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

  18. Biaxial Compressive Strain Engineering in Graphene/Boron Nitride Heterostructures

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  19. Axial residual stresses in boron fibers

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.

    1978-01-01

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

  20. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chao, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-11-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

  1. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chou, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-03-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

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

    PubMed Central

    Blevins, D G; Lukaszewski, K M

    1994-01-01

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

  3. Boron isotope systematics of hydrothermal fluids from submarine hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Yamaoka, K.; Hong, E.; Ishikawa, T.; Gamo, T.; Kawahata, H.

    2013-12-01

    Boron is highly mobile in submarine hydrothermal systems and useful to trace the process of water-rock reaction. In this study, we measured the boron content and isotopic composition of vent fluids collected from arc-backarc hydrothermal systems in the western Pacific. In sediment-starved hydrothermal systems (Manus Basin, Suiyo Seamount, and Mariana Trough), the boron content and isotopic composition of vent fluids are dependent on type of host rock. The end member fluids from MORB-like basalt-hosted Vienna Woods in the Manus Basin showed low boron content and high δ11B value (0.53 mM, 29.8‰), while dacite-hosted PACMANUS and the Suiyo Seamount showed high boron contents and low δ11B values (1.45 and 1.52 mM, 13.6 and 18.5‰, respectively). The Alice Springs and Forecast Vent field in the Mariana Trough showed values intermediate between them (0.72 and 0.63 mM, 19.9 and 24.0‰, respectively), reflecting reaction of seawater and basalt influenced by slab material. In phase separated hydrothermal systems (North Fiji Basin), boron content and isotopic composition of vent fluids (0.44-0.56 mM, 34.5-35.9‰) were similar to those in the Vienna Woods. Considering little fractionation of boron and boron isotope during phase separation demonstrated by the previous experimental studies, it is suggested that the host rock in the North Fiji Basin is MORB-like basalt. In sediment-hosted hydrothermal system (Okinawa Trough), the reaction with boron-enriched sediment following seawater-rock reaction resulted in significantly high boron contents and low δ11B values of vent fluids (4.4-5.9 mM, 1.5-2.6‰). The water-sediment ratio was estimated to be ~2. In spite of the different geological settings, the end member fuids from all vent fields are enriched in B relative to seawater (0.41 mM, 39.6‰) and the δ11B values are inversely propotional to the boron concentrations. It suggests that boron isotopic composition of vent fluid predominantly depends on the amount of boron originated from solid-phase.

  4. Is Boron Nutritionally Relevant?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Evidence from numerous laboratories using a variety of experimental models, including humans, shows that boron is a bioactive beneficial element. Much evidence has come from studies that did not require nutritional or environmental stressors or fastidious methods in diet preparation or environmental...

  5. Boron and Compounds

    Integrated Risk Information System (IRIS)

    Boron and Compounds ; CASRN 7440 - 42 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  6. 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

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

    2001-01-01

    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.

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

    PubMed

    Green, N R; Ferrando, A A

    1994-11-01

    Recently, a proliferation of athletic supplements has been marketed touting boron as an ergogenic aid capable of increasing testosterone. The effect of boron supplementation was investigated in male bodybuilders. Ten male bodybuilders (aged 20 to 26) were given a 2.5-mg boron supplement, while nine male bodybuilders (aged 21 to 27) were given a placebo for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on day 1 and day 49 of the study. A microwave digestion procedure followed by inductively coupled argon plasma spectroscopy was used for boron determination. Twelve subjects had boron values at or above the detection limit with median value of 25 ng/ml (16 ng/ml lower quartile and 33 ng/ml upper quartile). Of the ten subjects receiving boron supplements, six had an increase in their plasma boron. Analysis of variance indicated no significant effect of boron supplementation on any of the other dependent variables. Both groups demonstrated significant increases in total testosterone (p < 0.01), lean body mass (p < 0.01), and one repetition maximum (RM) squat (p < 0.001) and one RM bench press (p < 0.01). The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser-trained bodybuilders, but boron supplementation affects these variables not at all. PMID:7889885

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  9. Nothing Boring About Boron.

    PubMed

    Pizzorno, Lara

    2015-08-01

    The trace mineral boron is a micronutrient with diverse and vitally important roles in metabolism that render it necessary for plant, animal, and human health, and as recent research suggests, possibly for the evolution of life on Earth. As the current article shows, boron has been proven to be an important trace mineral because it (1) is essential for the growth and maintenance of bone; (2) greatly improves wound healing; (3) beneficially impacts the body's use of estrogen, testosterone, and vitamin D; (4) boosts magnesium absorption; (5) reduces levels of inflammatory biomarkers, such as high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor α (TNF-α); (6) raises levels of antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase; (7) protects against pesticide-induced oxidative stress and heavy-metal toxicity; (8) improves the brains electrical activity, cognitive performance, and short-term memory for elders; (9) influences the formation and activity of key biomolecules, such as S-adenosyl methionine (SAM-e) and nicotinamide adenine dinucleotide (NAD(+)); (10) has demonstrated preventive and therapeutic effects in a number of cancers, such as prostate, cervical, and lung cancers, and multiple and non-Hodgkin's lymphoma; and (11) may help ameliorate the adverse effects of traditional chemotherapeutic agents. In none of the numerous studies conducted to date, however, do boron's beneficial effects appear at intakes > 3 mg/d. No estimated average requirements (EARs) or dietary reference intakes (DRIs) have been set for boron-only an upper intake level (UL) of 20 mg/d for individuals aged ≥ 18 y. The absence of studies showing harm in conjunction with the substantial number of articles showing benefits support the consideration of boron supplementation of 3 mg/d for any individual who is consuming a diet lacking in fruits and vegetables or who is at risk for or has osteopenia; osteoporosis; osteoarthritis (OA); or breast, prostate, or lung cancer. PMID:26770156

  10. Process for microwave sintering boron carbide

    DOEpatents

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

    1993-10-12

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

  11. Process for microwave sintering boron carbide

    DOEpatents

    Holcombe, Cressie E.; Morrow, Marvin S.

    1993-01-01

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

  12. Low Temperature Treatment Affects Concentration and Distribution of Chrysanthemum Stunt Viroid in Argyranthemum.

    PubMed

    Zhang, Zhibo; Lee, YeonKyeong; Sivertsen, Astrid; Skjeseth, Gry; Haugslien, Sissel; Clarke, Jihong Liu; Wang, Qiao-Chun; Blystad, Dag-Ragnar

    2016-01-01

    Chrysanthemum stunt viroid (CSVd) can infect Argyranthemum and cause serious economic loss. Low temperature treatment combined with meristem culture has been applied to eradicate viroids from their hosts, but without success in eliminating CSVd from diseased Argyranthemum. The objectives of this work were to investigate (1) the effect of low temperature treatment combined with meristem culture on elimination of CSVd, (2) the effect of low temperature treatment on CSVd distribution pattern in shoot apical meristem (SAM), and (3) CSVd distribution in flowers and stems of two infected Argyranthemum cultivars. After treatment with low temperature combined with meristem tip culture, two CSVd-free plants were found in 'Border Dark Red', but none in 'Yellow Empire'. With the help of in situ hybridization, we found that CSVd distribution patterns in the SAM showed no changes in diseased 'Yellow Empire' following 5°C treatment, compared with non-treated plants. However, the CSVd-free area in SAM was enlarged in diseased 'Border Dark Red' following prolonged 5°C treatment. Localization of CSVd in the flowers and stems of infected 'Border Dark Red' and 'Yellow Empire' indicated that seeds could not transmit CSVd in these two cultivars, and CSVd existed in phloem. Results obtained in the study contributed to better understanding of the distribution of CSVd in systemically infected plants and the combination of low temperature treatment and meristem tip culture for production of viroid-free plants. PMID:26973607

  13. Oscillating bubble concentration and its size distribution using acoustic emission spectra.

    PubMed

    Avvaru, Balasubrahmanyam; Pandit, Aniruddha B

    2009-01-01

    New method has been proposed for the estimation of size and number density distribution of oscillating bubbles in a sonochemical reactor using acoustic emission spectra measurements. Bubble size distribution has been determined using Minnaert's equation [M. Minnaert, On musical air bubbles and sound of running water, Philanthr. Mag. 16 (1933) 235], i.e., size of oscillating bubble is inversely related to the frequency of its volume oscillations. Decomposition of the pressure signal measured by the hydrophone in frequency domain of FFT spectrum and then inverse FFT reconstruction of the signal at each frequency level has been carried out to get the information about each of the bubble/cavity oscillation event. The number mean radius of the bubble size is calculated to be in the range of 50-80 microm and it was not found to vary much with the spatial distribution of acoustic field strength of the ultrasound processor used in the work. However, the number density of the oscillating bubbles and the nature of the distribution were found to vary in different horizontal planes away from the driving transducer surface in the ultrasonic bath. A separate set of experiments on erosion assessment studies were carried out using a thin aluminium foil, revealing a phenomena of active region of oscillating bubbles at antinodal points of the stationary waves, identical to the information provided by the acoustic emission spectra at the same location in the ultrasonic bath. PMID:18752981

  14. Low Temperature Treatment Affects Concentration and Distribution of Chrysanthemum Stunt Viroid in Argyranthemum

    PubMed Central

    Zhang, Zhibo; Lee, YeonKyeong; Sivertsen, Astrid; Skjeseth, Gry; Haugslien, Sissel; Clarke, Jihong Liu; Wang, Qiao-Chun; Blystad, Dag-Ragnar

    2016-01-01

    Chrysanthemum stunt viroid (CSVd) can infect Argyranthemum and cause serious economic loss. Low temperature treatment combined with meristem culture has been applied to eradicate viroids from their hosts, but without success in eliminating CSVd from diseased Argyranthemum. The objectives of this work were to investigate (1) the effect of low temperature treatment combined with meristem culture on elimination of CSVd, (2) the effect of low temperature treatment on CSVd distribution pattern in shoot apical meristem (SAM), and (3) CSVd distribution in flowers and stems of two infected Argyranthemum cultivars. After treatment with low temperature combined with meristem tip culture, two CSVd-free plants were found in ‘Border Dark Red’, but none in ‘Yellow Empire’. With the help of in situ hybridization, we found that CSVd distribution patterns in the SAM showed no changes in diseased ‘Yellow Empire’ following 5°C treatment, compared with non-treated plants. However, the CSVd-free area in SAM was enlarged in diseased ‘Border Dark Red’ following prolonged 5°C treatment. Localization of CSVd in the flowers and stems of infected ‘Border Dark Red’ and ‘Yellow Empire’ indicated that seeds could not transmit CSVd in these two cultivars, and CSVd existed in phloem. Results obtained in the study contributed to better understanding of the distribution of CSVd in systemically infected plants and the combination of low temperature treatment and meristem tip culture for production of viroid-free plants. PMID:26973607

  15. DISTRIBUTION OF FINGERLING BROOK TROUT, SALVELINUS FONTINALIS (MITCHELL), IN DISSOLVED OXYGEN CONCENTRATION GRADIENTS

    EPA Science Inventory

    A self-recording linear gradient tank and procedures are described in which individual brook trout fingerlings unstressed by recent transfer, unaccustomed surroundings or the presence of an observer could move freely in 16 oxygen concentration gradients within the limits of 1 and...

  16. Distribution and Diversity of Escherichia and Salmonella isolates obtained from beef cattle concentrated animal feeding operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Southern High Plains are home to numerous cattle feedlots containing approximately 3.5 million beef cattle that account for nearly 30% of the United States fed beef cattle operations. The high density of beef cattle results in a concentration of nutrients (C, N, and P) due to the generation of m...

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

    PubMed

    Brooks, S P; Storey, K B

    1993-05-12

    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 2 mM iodoacetic acid (IAA) to an incubation medium containing tissues isolated from the channelled whelk Busycon canaliculatum. Iodoacetic acid inhibited glyceraldehyde 3-phosphate dehydrogenase activity causing a 100-400 fold increase in the concentration of fructose 1,6-bisphosphate as well as 3-20 fold increases in glucose 6-phosphate, fructose 6-phosphate, and dihydroxyacetone phosphate levels depending on the experimental protocol. Cellular pH values were not statistically different in the presence of IAA. Measurement of enzyme binding to particulate matter showed that the binding of phosphofructokinase, aldolase and pyruvate kinase was unaffected by iodoacetic acid under any experimental condition. These results show that changes in the tissue concentrations of enzyme substrates and products do not regulate enzyme binding to particulate matter in the cell. PMID:8350861

  18. 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...

  19. Electrical properties and hyperfine interactions of boron doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Amir, Md; Ünal, B.; Geleri, M.; Güngüneş, H.; Shirsath, Sagar E.; Baykal, A.

    2015-12-01

    The single spinel phase nano-structured particles of FeBxFe2-xO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized by the glycothermal method and the effect of B3+ substitution on structural and dielectric properties of Fe3O4 were studied. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on B3+ substitution have been determined. The hyperfine field values at B- and A-sites gradually decrease with increasing B3+ ion concentration (x). The cation distributions obtained from Bertaut method are in line with Mössbauer results. Complex impedance analysis of boron-substituted spinel ferrites have been made extensively in order to investigate the significant changes in ac and dc conductivity as well as complex permittivity when the boron composition ratio varies from 0.1 to 0.5. It is found that both ac and dc conductivity are also dependent on the boron content in addition to both temperature and applied frequency. The dc conductivity tendency does not purely obey the Arrhenius plots. The dielectric constant and loss of complex permittivity, in general, show similar attitudes as seen in some nanocomposites containing spinel ferrites except for some fluctuations and shifts along the characteristics of the curves. Furthermore, their imaginary components of both permittivity and modulus are almost found to obey the power law with any exponent values varying between 0.5 and 2 in accordance with the level of boron concentrations.

  20. Methods of producing continuous boron carbide fibers

    SciTech Connect

    Garnier, John E.; Griffith, George W.

    2015-12-01

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

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

    PubMed

    Ko, Cengiz

    2007-02-01

    Boron toxicity is an important disorder that can be limit plant growth on soils of arid and semi arid environments through the world. High concentrations of Boron may occur naturally in the soil or in groundwater, or be added to the soil from mining, fertilizers, or irrigation water. Off all the potential resources, irrigation water is the most important contributor to high levels of soil boron, boron is often found in high concentrations in association with saline soil and saline well water. Although of considerable agronomic importance, our understanding of Boron toxicity is rather fragment and limited. In this study, Boron content of Great Menderes River and Basin was researched. Great Menderes Basin is one of the consequence basins having agricultural potential, aspect of water and soil resources in Turkey. Great Menderes River, water resource of the basin was to be polluted by geothermal wastewater and thermal springs including Boron element. Great Menderes Basin has abundant geothermal water resources which contain high amounts of Boron and these ground water are brought to surface and used for various purposes such as power generation, heating or thermal spring and than discharged to Great Menderes River. In order to prevent Boron pollution and hence unproductively in soils, it is necessary not to discharged water with Boron to irrigation water. According to results, it was obtained that Boron content of River was as high in particular Upper Basin where there was a ground thermal water reservoir. Boron has been accumulated more than plant requirement in this area irrigated by this water. Boron content of River was relatively low in rainy months and irrigation season while it was high in dry season. Boron concentration in the River was to decrease from upstream to downstream. If it is no taken measure presently, about 130,000 ha irrigation areas which was constructed irrigation scheme in the Great Menderes basin will expose the Boron pollution and salinity. Even though Boron concentration of river water is under 0.5 ppm limit value, Boron element will store in basin soils, decrease in crop yields, and occur problematic soils in basin. PMID:17171286

  2. Distributional patterns of arsenic concentrations in contaminant plumes offer clues to the source of arsenic in groundwater at landfills

    USGS Publications Warehouse

    Harte, Philip T.

    2015-01-01

    The distributional pattern of dissolved arsenic concentrations from landfill plumes can provide clues to the source of arsenic contamination. Under simple idealized conditions, arsenic concentrations along flow paths in aquifers proximal to a landfill will decrease under anthropogenic sources but potentially increase under in situ sources. This paper presents several conceptual distributional patterns of arsenic in groundwater based on the arsenic source under idealized conditions. An example of advanced subsurface mapping of dissolved arsenic with geophysical surveys, chemical monitoring, and redox fingerprinting is presented for a landfill site in New Hampshire with a complex flow pattern. Tools to assist in the mapping of arsenic in groundwater ultimately provide information on the source of contamination. Once an understanding of the arsenic contamination is achieved, appropriate remedial strategies can then be formulated.

  3. Influence of droplet distribution in a ``water slug'' on the temperature and concentration of combustion products in its wake

    NASA Astrophysics Data System (ADS)

    Strizhak, P. A.

    2013-07-01

    A numerical study has been made of the influence of the droplet distribution in a “water slug” on the integral characteristics of heat and mass transfer (temperature and concentration of the gases in its wake) in motion through high-temperature combustion products of typical combustible wood. Limiting values of the parameters characterizing the position of the droplets relative to the neighboring droplets in the “water slug” at which minimum temperatures and concentrations of the combustion products in its wake are attained under the conditions of the greatest possible completeness of water evaporation, have been established. It has been shown that a series-parallel droplet distribution in the “water slug” is expedient for efficient action on the high-temperature gases.

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

    PubMed

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

    2013-11-01

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

  5. Concentration and Spatial Distribution of Selected Constituents in Detroit River Bed Sediment Adjacent to Grassy Island, Michigan, August 2006

    USGS Publications Warehouse

    Hoard, C.J.

    2008-01-01

    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.

  6. [Boron in dental hard tissues studied by 11B(p,alpha)8Be nuclear reaction].

    PubMed

    Torrisi, L; Rapisarda, E; Cicero, G

    1989-09-01

    Boron's low atomic number and low concentration make its measurement in hard dental tissues difficult. Using nuclear reaction, the 11B(p,alpha)8Be*, enamel, dentine and radicular cement of 18 dental elements, ten healthy and eight decayed teeth, both permanent and deciduous were studied. The highest Boron concentrations were found in the two most superficial microns of the vestibular enamel in non-decayed incisors, particularly deciduous ones. Premolar and molar teeth showed lower Boron concentrations than frontal ones, decayed teeth revealed hardly any Boron. In confirmation of the prevailing exogenous contribution of this karyostatic trace element, on average, Boron concentrations were 2.5 times as high as dentine and 10 times as high as cement. PMID:2811808

  7. Toward a clinical application of ex situ boron neutron capture therapy for lung tumors at the RA-3 reactor in Argentina

    SciTech Connect

    Farías, R. O.; Trivillin, V. A.; Portu, A. M.; Schwint, A. E.; González, S. J.; Garabalino, M. A.; Monti Hughes, A.; Pozzi, E. C. C.; Thorp, S. I.; Curotto, P.; Miller, M. E.; Santa Cruz, G. A.; Saint Martin, G.; Ferraris, S.; Santa María, J.; Rovati, O.; Lange, F.; Bortolussi, S.; Altieri, S.

    2015-07-15

    Purpose: Many types of lung tumors have a very poor prognosis due to their spread in the whole organ volume. The fact that boron neutron capture therapy (BNCT) would allow for selective targeting of all the nodules regardless of their position, prompted a preclinical feasibility study of ex situ BNCT at the thermal neutron facility of RA-3 reactor in the province of Buenos Aires, Argentina. (L)-4p-dihydroxy-borylphenylalanine fructose complex (BPA-F) biodistribution studies in an adult sheep model and computational dosimetry for a human explanted lung were performed to evaluate the feasibility and the therapeutic potential of ex situ BNCT. Methods: Two kinds of boron biodistribution studies were carried out in the healthy sheep: a set of pharmacokinetic studies without lung excision, and a set that consisted of evaluation of boron concentration in the explanted and perfused lung. In order to assess the feasibility of the clinical application of ex situ BNCT at RA-3, a case of multiple lung metastases was analyzed. A detailed computational representation of the geometry of the lung was built based on a real collapsed human lung. Dosimetric calculations and dose limiting considerations were based on the experimental results from the adult sheep, and on the most suitable information published in the literature. In addition, a workable treatment plan was considered to assess the clinical application in a realistic scenario. Results: Concentration-time profiles for the normal sheep showed that the boron kinetics in blood, lung, and skin would adequately represent the boron behavior and absolute uptake expected in human tissues. Results strongly suggest that the distribution of the boron compound is spatially homogeneous in the lung. A constant lung-to-blood ratio of 1.3 ± 0.1 was observed from 80 min after the end of BPA-F infusion. The fact that this ratio remains constant during time would allow the blood boron concentration to be used as a surrogate and indirect quantification of the estimated value in the explanted healthy lung. The proposed preclinical animal model allowed for the study of the explanted lung. As expected, the boron concentration values fell as a result of the application of the preservation protocol required to preserve the lung function. The distribution of the boron concentration retention factor was obtained for healthy lung, with a mean value of 0.46 ± 0.14 consistent with that reported for metastatic colon carcinoma model in rat perfused lung. Considering the human lung model and suitable tumor control probability for lung cancer, a promising average fraction of controlled lesions higher than 85% was obtained even for a low tumor-to-normal boron concentration ratio of 2. Conclusions: This work reports for the first time data supporting the validity of the ovine model as an adequate human surrogate in terms of boron kinetics and uptake in clinically relevant tissues. Collectively, the results and analysis presented would strongly suggest that ex situ whole lung BNCT irradiation is a feasible and highly promising technique that could greatly contribute to the treatment of metastatic lung disease in those patients without extrapulmonary spread, increasing not only the expected overall survival but also the resulting quality of life.

  8. Caenorhabditis elegans Maintains Highly Compartmentalized Cellular Distribution of Metals and Steep Concentration Gradients of Manganese

    PubMed Central

    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

    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. PMID:22393436

  9. Boron isotopic compositions of some boron minerals

    NASA Astrophysics Data System (ADS)

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

    1989-12-01

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

  10. Concentration and distribution of PCNs in ambient soil of a municipal solid waste incinerator.

    PubMed

    Tian, Zhenyu; Li, Haifeng; Xie, Huiting; Tang, Chen; Han, Ying; Liu, Wenbin

    2014-09-01

    The impact of a typical municipal solid waste incinerator (MSWI) on polychlorinated naphthalene (PCN) concentrations in surrounding soil was studied. We collected 6 stack gas samples from the MSWI and 21 soil samples from sampling sites at distances of between 300 and 1,700 m from the MSWI stack. Total dl-PCN (dioxin-like PCN) concentrations in the stack gas samples ranged from 6898 and 89,032 pg m(-3), with a mean value of 36,241 pg m(-3). The total dl-PCN concentrations in the soil samples ranged from 30.35 to 280.9 pg g(-1), with a mean value of 87.03 and a median value of 70.32 pg g(-1), while the TEQ values were between 7.7 and 130.2 fg TEQ g(-1), with a mean value of 41.12 fg TEQ g(-1) and a median value of 31.52fg TEQ g(-1). The PCN homologue patterns and the results of Principal Component Analysis suggested that the MSWI may be a source of PCNs in the soils. A contour map, created using an ordinary Kriging interpolation technique, showed that a limited area (≤ 1,000 m radius) surrounding the MSWI was influenced by the emissions from the MSWI. Furthermore, an exponential function equation was proposed to quantify the relationship between TEQs of PCNs and the distance from the stack. PMID:24457132

  11. [Low triiodothyronine syndrome in non thyroidal diseases. Distribution and serum TSH concentration studies (author's transl)].

    PubMed

    Linquette, M; Lefebvre, J; Fourlinnie, J C; Wemeau, J L

    1978-01-01

    Thyroid explorations were made in 57 patients complaining of serious illnesses in order to identify "low T3 syndrome". All these patients were clinically euthyroid as assessed by normal values of T4 concentration, RT3U ratio and FT4I. However, all the patients included in this study had significantly low serum T3 (42 +/- 29 ng/100 ml) and FT3I (0,44 +/- 0,30). Low T3 syndrome was particularly frequently seen in patients with cancer (8/10), hepatic cirrhosis (5/6), renal failure (6/7), old age (5/8) and in serious systemic diseases (6/12). Nevertheless, at adverse with other authors, we have observed less frequently the low T3 syndrome in anorexia nervosa (4/6) as well as during fasting (1/8). In 31 out of 35 patients with low or normal low T3 concentrations, the serum TSH values observed were within the normal limits in 28 cases. The etiologies of isolated decreased T3, mainly the deviation of peripheral conversion of T4 to reverse T3, are discussed. Normal metabolic state and normal TSH concentration encountered in the low T3 syndrome are equally commented. PMID:736516

  12. Sensitivity of aerosol concentrations and cloud properties to nucleation and secondary organic distribution in ECHAM5-HAM global circulation model

    NASA Astrophysics Data System (ADS)

    Makkonen, R.; Asmi, A.; Korhonen, H.; Kokkola, H.; Järvenoja, S.; Räisänen, P.; Lehtinen, K. E. J.; Laaksonen, A.; Kerminen, V.-M.; Järvinen, H.; Lohmann, U.; Bennartz, R.; Feichter, J.; Kulmala, M.

    2009-03-01

    The global aerosol-climate model ECHAM5-HAM was modified to improve the representation of new particle formation in the boundary layer. Activation-type nucleation mechanism was introduced to produce observed nucleation rates in the lower troposphere. A simple and computationally efficient model for biogenic secondary organic aerosol (BSOA) formation was implemented. Here we study the sensitivity of the aerosol and cloud droplet number concentrations (CDNC) to these additions. Activation-type nucleation significantly increases aerosol number concentrations in the boundary layer. Increased particle number concentrations have a significant effect also on cloud droplet number concentrations and therefore on cloud properties. We performed calculations with activation nucleation coefficient values of 2×10-7s-1, 2×10-6s-1 and 2×10-5s-1 to evaluate the sensitivity to this parameter. For BSOA we have used yields of 0.025, 0.07 and 0.15 to estimate the amount of monoterpene oxidation products available for condensation. The hybrid BSOA formation scheme induces large regional changes to size distribution of organic carbon, and therefore affects particle optical properties and cloud droplet number concentrations locally. Although activation-type nucleation improves modeled aerosol number concentrations in the boundary layer, the use of a global activation coefficient generally leads to overestimation of aerosol number. Overestimation can also arise from underestimation of primary emissions.

  13. Sampling and analysis of chemical element concentration distribution in rock units and orebodies

    NASA Astrophysics Data System (ADS)

    Agterberg, F. P.

    2012-01-01

    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.

  14. Urinary phthalate metabolite concentrations among pregnant women in Northern Puerto Rico: Distribution, temporal variability, and predictors

    PubMed Central

    Cantonwine, David E.; Cordero, José F.; Rivera-González, Luis O.; Del Toro, Liza V. Anzalota; Ferguson, Kelly K.; Mukherjee, Bhramar; Calafat, Antonia M.; Crespo, Noe; Jiménez-Vélez, Braulio; Padilla, Ingrid Y.; Alshawabkeh, Akram N.; Meeker, John D.

    2013-01-01

    Background Phthalate contamination exists in the North coast karst aquifer system in Puerto Rico. In light of potential health impacts associated with phthalate exposure, targeted action for elimination of exposure sources may be warranted, especially for sensitive populations such as pregnant women. However, information on exposure to phthalates from a variety of sources in Puerto Rico is lacking. The objective of this study was to determine concentrations and predictors of urinary phthalate biomarkers measured at multiple times during pregnancy among women living in the Northern karst area of Puerto Rico. Methods We recruited 139 pregnant women in Northern Puerto Rico and collected urine samples and questionnaire data at three separate visits (18±2 weeks, 22±2 weeks, and 26±2 weeks of gestation). Urine samples were analyzed for eleven phthalate metabolites: mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate, mono-2-ethyl-5-oxohexyl phthalate, mono-2-ethyl-5-carboxypentyl phthalate, mono-ethyl phthalate (MEP), mono-n-butyl phthalate, mono-benzyl phthalate, mono-isobutyl phthalate, mono-3-carboxypropyl phthalate (MCPP), mono carboxyisononyl phthalate (MCNP), and mono carboxyisooctyl phthalate (MCOP). Results Detectable concentrations of phthalate metabolites among pregnant women living in Puerto Rico was prevalent, and metabolite concentrations tended to be higher than or similar to those measured in women of reproductive age from the general US population. Intraclass correlation coefficients ranged from very weak (MCNP; 0.05) to moderate (MEP; 0.44) reproducibility among all phthalate metabolites. We observed significant or suggestive positive associations between urinary phthalate metabolites concentrations and water usage/storage habits (MEP, MCNP, MCOP), use of personal care products (MEP), and consumption of certain food items (MCPP, MCNP, and MCOP). Conclusions To our knowledge this is the first study to report concentrations, temporal variability, and predictors of phthalate biomarkers among pregnant women in Puerto Rico. Preliminary results suggest several potentially important exposure sources to phthalates in this population and future analysis from this ongoing prospective cohort will help to inform targeted approaches to reduce exposure. PMID:24161445

  15. [Analysis on concentration, distribution and budgets of Mn and Zn in soybean by using ICP-AES].

    PubMed

    Zhou, Hua; Jiang, Chun-Ming; Xu, Yong-Gang; Ma, Qiang

    2013-04-01

    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

  16. Distribution of uranium concentration in groundwater samples from the Peddagattu/Nambapur and Seripally regions using laser fluorimetry.

    PubMed

    Raghavendra, T; Srilatha, K; Mahender, C; Elander, M; Vijayalakshmi, T; Himabindu, V; Prasad, Vishwa; Padma Savithri, P; Datta, D; Arunachalam, J

    2014-01-01

    Uranium is a naturally occurring element, which is widespread in nature. It is found in low levels within all rocks, soils and water. Peddagattu and Seripally areas of Nalgonda district, Andhra Pradesh, India were known as a rich uranium mineralised zone. Atomic mineral division and Baba Atomic Research Center proposed a uranium mine in this area. This study was carried out to know the distribution of uranium concentration in the groundwater samples by using laser fluorimetry. The observation reveals that the uranium concentration in the groundwater of this region ranges from 0.6 to 521.15 ppb. About 43 % of the groundwater samples had the uranium concentration above the standards set by United States Environmental Protection Agency (30 ppb). PMID:24048245

  17. Numerical simulation on the effects of drug eluting stents at different Reynolds numbers on hemodynamic and drug concentration distribution

    PubMed Central

    2015-01-01

    Background The changes of hemodynamics and drug concentration distribution caused by the implantation of drug eluting stents (DESs) in curved vessels have significant effects on In-Stent Restenosis. Methods A 3D virtual stent with 90°curvature was modelled and the distribution of wall shear stress (WSS) and drug concentration in this model were numerically studied at Reynolds numbers of 200, 400, 600, 800. Results The results showed that (1) the intensity of secondary flow at the 45° cross-section was stronger than that at the 90° cross-section; (2) As the Reynolds number increases, the WSS decreases. When the Reynolds number reaches 600, the low-WSS region only accounts for 3% of the total area. (3) The effects of Reynolds number on drug concentration in the vascular wall decreases in proportionally and then the blood velocity increased 4 times, the drug concentration in the vascular wall decreased by about 30%. (4) The size of the high drug concentration region is inversely proportional to the Reynolds number. As the blood velocity increases, the drug concentration in the DES decreases, especially at the outer bend. Conclusions It is beneficial for the patient to decrease vigorous activities and keep calm at the beginning of the stent implantation, because a substantial amount of the drug is released in the first two months of stent implantation, thus a calm status is conducive to drug release and absorption; Subsequently, appropriate exercise which increases the blood velocity is helpful in decreasing regions of low-WSS. PMID:25602685

  18. Unintentional boron contamination of MBE-grown GaInP/AlGaInP quantum wells

    NASA Astrophysics Data System (ADS)

    Tukiainen, Antti; Likonen, Jari; Toikkanen, Lauri; Leinonen, Tomi

    2015-09-01

    The effects of unintentional boron contamination on optical properties of GaInP/AlGaInP quantum well structures grown by molecular beam epitaxy (MBE) are reported. Photoluminescence and secondary-ion mass spectrometry (SIMS) measurements revealed that the optical activity of boron-contaminated quantum wells is heavily affected by the amount of boron in GaInP/AlGaInP heterostructures. The boron concentration was found to increase when cracking temperature of the phosphorus source was increased. Boron incorporation was enhanced also when aluminum was present in the material.

  19. Multipurpose boron carbide-aluminum composite and its manufacture via the control of the microstructure

    SciTech Connect

    Pyzik, A.J.; Aksay, I.A.

    1987-10-27

    A method of making a boron carbidealuminum composite is described comprising: heating a particulate boron carbide in the presence of free carbon to 1800/sup 0/-2250/sup 0/C wherein the resulting boron carbide exhibits a substantially reduced reaction rate with aluminum; and reacting the boron carbide with aluminum, wherein a boron carbide-aluminum composite is formed having a microstructure including principally boron carbide and aluminum metal homogeneously distributed throughout the composite. A method is described of making a boron carbide-aluminum composite of selected ceramic and metal content and microstructure, having high fracture toughness, fracture strength and Young's modulus, and low density. It consists of: dispersing a particulate boron carbide of less than 10 micrometers particle size in water at a pH selected to maximize electrostatic repelling forces on boron carbide particle surfaces; consolidating the boron carbide into a porous compact; sintering the compact, whereby an open porous structure is retained; infilterating the compact with aluminum; and heat treating the compact, whereby a voidless composite is formed having microstructure phases.

  20. Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

    NASA Astrophysics Data System (ADS)

    Cao, Limin; Zhang, Ze; Wang, Wenkui

    2004-08-01

    One-dimensionally nanostructured materials, such as nanowires and nanotubes, are the smallest dimensional structures for efficient transport of electrons and excitons, and are therefore critical building blocks for nanoscale electronic and mechanical devices. In this paper, boron nanowires with uniform diameters from 20 to 80 nm were synthesized by radio-frequency magnetron sputtering of pure boron powder and B2O3 powder mixtures in argon atmosphere. The boron nanowires produced stand vertically on the substrate surface to form well-ordered arrays over large areas with self-organized arrangements without involvement of any template and patterned catalyst. The high-density boron nanowires are parallel to each other and well distributed, forming highly ordered and uniform arrays. A more interesting and unique feature of the boron nanowires is that most of their tips are flat rather than hemispherical in morphologies. Detailed studies on its structure and composition indicate that boron nanowires are amorphous. Boron nanowire appears as a new member in the family of one-dimensional nanostructures. Considering the unique properties of boron-rich solids and other nanostructures, it is reasonable to expect that the boron nanowires will display some exceptional and interesting properties. A vapor-cluster-solid (VCS) mechanism was proposed to explain the growth of boron nanowires based on our experimental observations.

  1. Characterization of concentration, particle size distribution, and contributing factors to ambient hexavalent chromium in an area with multiple emission sources

    NASA Astrophysics Data System (ADS)

    Yu, Chang Ho; Huang, Lihui; Shin, Jin Young; Artigas, Francisco; Fan, Zhi-hua (Tina)

    2014-09-01

    Airborne hexavalent chromium (Cr(VI)) is a known pulmonary carcinogen and can be emitted from both natural and anthropogenic sources, including diesel emissions. However, there is limited knowledge about ambient Cr(VI) concentration levels and its particle size distribution. This pilot study characterized ambient Cr(VI) concentrations in the New Jersey Meadowlands (NJ ML) district, which is close to the heavily trafficked New Jersey Turnpike (NJTPK) as well as Chromium Ore Processing Residue (COPR) waste sites. Monitoring was simultaneously conducted at two sites, William site (∼50 m from NJTPK) and MERI site (∼700 m from NJTPK). The distance between the two sites is approximately 6.2 km. Ambient Cr(VI) concentrations and PM2.5 mass concentrations were concurrently measured at both sites during summer and winter. The summer concentrations (mean ± S.D. [median]), 0.13 ± 0.06 [0.12] ng/m3 at the MERI site and 0.08 ± 0.05 [0.07] ng/m3 at the William site, were all significantly higher than the winter concentrations, 0.02 ± 0.01 [0.02] ng/m3 and 0.03 ± 0.01 [0.03] ng/m3 at the MERI and William sites, respectively. The site difference (i.e., MERI > William) was observed for summer Cr(VI) concentrations; however, no differences for winter and pooled datasets. These results suggest higher Cr(VI) concentrations may be attributed from stronger atmospheric reactions such as photo-oxidation of Cr(III) to Cr(VI) in the summer. The Cr(VI) distribution as a function of particle size, ranging from 0.18 to 18 μm, was determined at the William site. It was found that Cr(VI) was enriched in the particles less than 2.5 μm in diameter (PM2.5). This finding suggested potential health concerns, because PM2.5 are easily inhaled and deposited in the alveoli. A multiple linear regression analysis confirmed ambient Cr(VI) concentrations were significantly affected by meteorological factors (i.e., temperature and humidity) and reactive gases/particles (i.e., O3, Fe and Mn).

  2. Distribution Characteristics, Concentrations, and Sources of Cd and Pb in Laoxiawan Channel Sediments from Zhuzhou, China.

    PubMed

    Chen, Wen-Wen; Zhang, Jian-Xin; Abass, Olusegun-Kazeem; Wen, Xin-Yu; Huang, Huan-Fang; Qu, Cheng-Kai; Qi, Shi-Hua

    2016-06-01

    Twenty sediment cores encompassing surface (0-20 cm) and deeper (50-60 cm) sediment layers were retrieved from the 3000 m-long Laoxiawan Channel, which receives industrial effluents from Zhuzhou City (China). Analytical results showed that cadmium (Cd) concentrations ranged between 115.7-1126.7 and 108.8-2059.3 mg/kg while lead (Pb) values ranged between 234-3000 and 145-4292 mg/kg in the surface and bottom sediments, respectively. The results also indicated that high levels of Cd and Pb were present in the vicinity of the channel mouth and confluence area. Indices for potential ecological risk and geo-accumulation were used to evaluate the environmental effects and intensity of heavy metal pollution over time. High concentrations of Cd and Pb in the bottom sediments of Laoxiawan Channel were mainly associated with wastewater discharge (10(6) m(3)/year). Thus, the Laoxiawan Channel may be an important metal contaminant source for the Xiang River. PMID:27025765

  3. Boron Neutron Capture Therapy (BCNT) for the Treatment of Liver Metastases: Biodistribution Studies of Boron Compounds in an Experimental Model

    SciTech Connect

    Marcela A. Garabalino; Andrea Monti Hughes; Ana J. Molinari; Elisa M. Heber; Emiliano C. C. Pozzi; Maria E. Itoiz; Veronica A. Trivillin; Amanda E. Schwint; Jorge E. Cardoso; Lucas L. Colombo; Susana Nievas; David W. Nigg; Romina F. Aromando

    2011-03-01

    Abstract We previously demonstrated the therapeutic efficacy of different boron neutron capture therapy (BNCT) protocols in an experimental model of oral cancer. BNCT is based on the selective accumulation of 10B carriers in a tumor followed by neutron irradiation. Within the context of exploring the potential therapeutic efficacy of BNCT for the treatment of liver metastases, the aim of the present study was to perform boron biodistribution studies in an experimental model of liver metastases in rats. Different boron compounds and administration conditions were assayed to determine which administration protocols would potentially be therapeutically useful in in vivo BNCT studies at the RA-3 nuclear reactor. A total of 70 BDIX rats were inoculated in the liver with syngeneic colon cancer cells DHD/K12/TRb to induce the development of subcapsular tumor nodules. Fourteen days post-inoculation, the animals were used for biodistribution studies. We evaluated a total of 11 administration protocols for the boron compounds boronophenylalanine (BPA) and GB-10 (Na210B10H10), alone or combined at different dose levels and employing different administration routes. Tumor, normal tissue, and blood samples were processed for boron measurement by atomic emission spectroscopy. Six protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue. Boron concentration values in tumor and normal tissues in the liver metastases model show it would be feasible to reach therapeutic BNCT doses in tumor without exceeding radiotolerance in normal tissue at the thermal neutron facility at RA-3.

  4. Boron neutron capture therapy (BNCT) for the treatment of liver metastases: biodistribution studies of boron compounds in an experimental model.

    PubMed

    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

    2011-03-01

    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

  5. Air pollutants in rural homes in Guizhou, China - Concentrations, speciation, and size distribution

    NASA Astrophysics Data System (ADS)

    Wang, Shuxiao; Wei, Wei; Li, Du; Aunan, Kristin; Hao, Jiming

    2010-11-01

    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 μg m -3 for PM 10 and 201˜304 μg 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 μg m -3). Coal combustion also resulted in higher concentrations of particulate matters (220˜250 μg m -3 for PM 10 and 170˜200 μg 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.

  6. Investigation of gasoline distributions within petrol stations: spatial and seasonal concentrations, sources, mitigation measures, and occupationally exposed symptoms.

    PubMed

    Sairat, Theerapong; Homwuttiwong, Sahalaph; Homwutthiwong, Kritsana; Ongwandee, Maneerat

    2015-09-01

    We measured levels of VOCs and determined the distributions of benzene concentrations over the area of two petrol stations in all three seasons. Using the concentrations and sampling positions, we created isoconcentration contour maps. The average concentrations ranged 18-1288 μg m(-3) for benzene and 12-81 μg m(-3) for toluene. The contour maps indicate that high-level contours of benzene were found not only at the fuel dispenser areas but also at the storage tank refilling points, open drainage areas where gasoline-polluted wastewater was flowing, and the auto service center located within the station area. An assessment of the benzene to toluene ratio contour plots implicates that airborne benzene and toluene near the fuel dispenser area were attributed to gasoline evaporation although one of the studied stations may be influenced by other VOC sources besides gasoline evaporation. Additionally, during the routine refilling of the underground fuel storage tanks by a tank truck, the ambient levels of benzene and toluene increased tremendously. The implementation of source control by replacing old dispensers with new fuel dispensers that have an efficient cutoff feature and increased delivery speed can reduce spatial benzene concentrations by 77%. Furthermore, a questionnaire survey among 63 service attendants in ten stations revealed that headache was the most reported health complaint with a response rate of 32%, followed by fatigue with 20%. These prominent symptoms could be related to an exposure to high benzene concentrations. PMID:25943517

  7. Sensitivity of aerosol concentrations and cloud properties to nucleation and secondary organic distribution in ECHAM5-HAM global circulation model

    NASA Astrophysics Data System (ADS)

    Makkonen, R.; Asmi, A.; Korhonen, H.; Kokkola, H.; Järvenoja, S.; Räisänen, P.; Lehtinen, K. E. J.; Laaksonen, A.; Kerminen, V.-M.; Järvinen, H.; Lohmann, U.; Feichter, J.; Kulmala, M.

    2008-06-01

    The global aerosol-climate model ECHAM5-HAM was modified to improve the representation of new particle formation in the boundary layer. Activation-type nucleation mechanism was introduced to produce observed nucleation rates in lower troposphere. A simple and computationally efficient model for biogenic secondary organic aerosol (BSOA) formation was implemented. We studied the sensitivity of aerosol and cloud droplet number concentrations (CDNC) to these additions. Activation-type nucleation significantly increases aerosol number concentrations in the boundary layer. Increased particle number concentrations have a significant effect also on cloud droplet number concentrations and therefore on cloud properties. We performed calculations with activation nucleation coefficient values of 2×10-7 s-1, 2×10-6 s-1 and 2×10-5 s-1 to evaluate the sensitivity to this parameter. For BSOA we have used yields of 0.025, 0.07 and 0.15 to estimate the amount of monoterpene oxidation products available for condensation. The dynamic SOA scheme induces large regional changes to size distribution of organic carbon, and therefore affects particle optical properties and cloud droplet number concentrations locally. Comparison with satellite observation shows that activation-type nucleation significantly decreases the differences between observed and modeled values of cloud top CDNC.

  8. Number concentration and size distribution of ultrafine particles on the roadside of the Tateyama-Kurobe Alpine route, Japan.

    PubMed

    Watanabe, Koichi; Honoki, Hideharu; Endo, Fuminori; Murakami, Takashi; Yoshida, Yuki; Iida, Hajime; Uehara, Yoshitoshi; Kume, Atsushi

    2011-01-01

    Measurements of ultrafine particles (UFPs) with diameters smaller than 100 nm were made with a Scanning Mobility Particle Sizer on the roadside of the Tateyama-Kurobe Alpine route on the western slope of Mt. Tateyama, Japan, in the summer and autumn of 2007 and 2008. The number concentrations of nanoparticles (NPs) with diameters smaller than 50 nm increased sharply in the morning. This increase agreed with that of the NO concentration, which is a good indicator of vehicle emissions. Although the peak concentration of NO was also detected in the late afternoon, the concentrations of NPs did not increase. The vehicle emission of UFPs may vary considerably with the driving conditions. The emission of NPs might have been accelerated under a high engine-load condition. The NP concentrations in October were much higher than those in August, although there were more buses in August than in October. The number size distribution in the morning was bimodal, with the first peak around 20-30 nm and the second one around 70-80 nm. The first peak became small during the daytime. The first peak disappeared, and a small second peak remained through midnight. PMID:21722082

  9. The place of solar power: an economic analysis of concentrated and distributed solar power

    PubMed Central

    2012-01-01

    Background This paper examines the cost and benefits, both financial and environmental, of two leading forms of solar power generation, grid-tied photovoltaic cells and Dish Stirling Systems, using conventional carbon-based fuel as a benchmark. Methods First we define how these solar technologies will be implemented and why. Then we delineate a model city and its characteristics, which will be used to test the two methods of solar-powered electric distribution. Then we set the constraining assumptions for each technology, which serve as parameters for our calculations. Finally, we calculate the present value of the total cost of conventional energy needed to power our model city and use this as a benchmark when analyzing both solar models’ benefits and costs. Results The preeminent form of distributed electricity generation, grid-tied photovoltaic cells under net-metering, allow individual homeowners a degree of electric self-sufficiency while often turning a profit. However, substantial subsidies are required to make the investment sensible. Meanwhile, large dish Stirling engine installations have a significantly higher potential rate of return, but face a number of pragmatic limitations. Conclusions This paper concludes that both technologies are a sensible investment for consumers, but given that the dish Stirling consumer receives 6.37 dollars per watt while the home photovoltaic system consumer receives between 0.9 and 1.70 dollars per watt, the former appears to be a superior option. Despite the large investment, this paper deduces that it is far more feasible to get few strong investors to develop a solar farm of this magnitude, than to get 150,000 households to install photovoltaic arrays in their roofs. Potential implications of the solar farm construction include an environmental impact given the size of land require for this endeavour. However, the positive aspects, which include a large CO2 emission reduction aggregated over the lifespan of the farm, outweigh any minor concerns or potential externalities. PMID:22540991

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

    SciTech Connect

    Reeber, R.R. ); Kusy, R.P. ); Yu, N.; Chu, W. )

    1990-03-12

    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.

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

    NASA Astrophysics Data System (ADS)

    Reeber, Robert R.; Kusy, Robert P.; Yu, Ning; Chu, Wei-Kan

    1990-03-01

    A boron nitride(lubricant)/boron carbide composite (approximately 70% boron nitride) has been formed in approximately the first 750 Å 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 4×1017 N ions/cm2 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.

  12. B28: the smallest all-boron cage from an ab initio global search

    NASA Astrophysics Data System (ADS)

    Zhao, Jijun; Huang, Xiaoming; Shi, Ruili; Liu, Hongsheng; Su, Yan; King, R. Bruce

    2015-09-01

    Our ab initio global searches reveal the lowest-energy cage for B28, which is built from two B12 units and prevails over the competing structural isomers such as planar, bowl, and tube. This smallest boron cage extends the scope of all-boron fullerene and provides a new structural motif of boron clusters and nanostructures.Our ab initio global searches reveal the lowest-energy cage for B28, which is built from two B12 units and prevails over the competing structural isomers such as planar, bowl, and tube. This smallest boron cage extends the scope of all-boron fullerene and provides a new structural motif of boron clusters and nanostructures. Electronic supplementary information (ESI) available: Planar isomer structures of B28 and spatial distributions of front molecular orbitals. See DOI: 10.1039/c5nr04034e

  13. Use of Uniformly Distributed Concentrated Sunlight for Highly Accelerated Testing of Coatings

    SciTech Connect

    Jorgensen, G.; Bingham, C.; King, D.; Lewandowski, A.; Netter, J.; Terwilliger, K.; Adamsons, K.

    2000-12-14

    NREL has developed a new ultraviolet (UV) light concentrator that allows material samples to be subjected to uniform intensity levels of 50-100X solar UV at closely controlled sample exposure temperatures. In collaboration with industry, representative coating systems have been exposed without introducing unrealistic degradation mechanisms. Furthermore, correlations have been derived between these highly accelerated test conditions and results obtained at 1-2 suns. Such information is used to predict the degradation of materials in real-world applications. These predictions are compared with measured in-service performance losses to validate the approach. This allows valuable information to be obtained in greatly reduced timeframes, which can provide tremendous competitive advantage in the commercial marketplace.

  14. Mineral oil in human tissues, Part I: concentrations and molecular mass distributions.

    PubMed

    Barp, Laura; Kornauth, Christoph; Wuerger, Tanja; Rudas, Margaretha; Biedermann, Maurus; Reiner, Angelika; Concin, Nicole; Grob, Koni

    2014-10-01

    Of 37 subjects aged 25-91 y (mean 67 y), mineral oil hydrocarbons were measured in subcutaneous abdominal fat tissue, mesenteric lymph nodes (MLN), spleen, liver and lung, for some of them also in kidney, heart and brain. No mineral oil aromatic hydrocarbons (MOAH) were detected. The mean concentration of mineral oil saturated hydrocarbons (MOSH) in the mesenteric lymph nodes was 223 mg/kg, in liver 131 mg/kg, in fat tissue 130 mg/kg, in spleen 93 mg/kg and in lung 12 mg/kg. They were clearly lower in kidney, heart and brain. The maxima, found in MLN and spleen, were 1390 and 1400 mg/kg, respectively. For a quarter of the subjects a total amount of MOSH in the body above 5 g was calculated. The MOSH composition in the fat tissue and the MLN appeared virtually identical and varied little between the subjects. It was centered on the n-alkanes C23-C24, ranged from C16 to C35 and included hydrocarbons of plant origin. The MOSH in spleen and liver had almost the same composition for a given subject, but varied somewhat between subjects. They were centered between C25 and C27, ranged from C18 to beyond C45 and were without hydrocarbons of plant origin. Part of the MOSH seem to be strongly accumulated, resulting in far higher concentrations in human tissues related to exposure than observed in shorter term animal experiments. The composition of the accumulated MOSH does not support that Class I mineral oils, sometimes termed "food grade", are less accumulated in the human body than Class II and III oils, which questions the present classification. PMID:24780493

  15. Fivefold twinned boron carbide nanowires.

    PubMed

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

    2009-09-01

    Chemical composition and crystal structure of fivefold twinned boron carbide nanowires have been determined by electron energy-loss spectroscopy and electron diffraction. The fivefold cyclic twinning relationship is confirmed by systematic axial rotation electron diffraction. Detailed chemical analysis reveals a carbon-rich boron carbide phase. Such boron carbide nanowires are potentially interesting because of their intrinsic hardness and high temperature thermoelectric property. Together with other boron-rich compounds, they may form a set of multiply twinned nanowire systems where the misfit strain could be continuously tuned to influence their mechanical properties. PMID:19687534

  16. Effect of traffic restriction on atmospheric particle concentrations and their size distributions in urban Lanzhou, Northwestern China.

    PubMed

    Zhao, Suping; Yu, Ye; Liu, Na; He, Jianjun; Chen, Jinbei

    2014-02-01

    During the 2012 Lanzhou International Marathon, the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To evaluate the direct effect of these measures on urban air quality, especially particle concentrations and their size distributions, atmospheric particle size distributions (0.5-20 microm) obtained using an aerodynamic particle sizer (model 3321, TSI, USA) in June 2012 were analyzed. It was found that the particle number, surface area and volume concentrations for size range 0.5-10 microm were (15.0 +/- 2.1) cm(-3), (11.8 +/- 2.6) microm2/cm3 and (1.9 +/- 0.6) microm2/cm3, respectively, on the traffic-restricted day (Sunday), which is 63.2%, 53.0% and 47.2% lower than those on a normal Sunday. For number and surface area concentrations, the most affected size range was 0.5-0.7 and 0.5-0.8 microm, respectively, while for volume concentration, the most affected size ranges were 0.5-0.8, 1.7-2.0 and 5.0-5.4 microm. Number and volume concentrations of particles in size range 0.5-1.0 microm correlated well with the number of non-CNG (Compressed Natural Gas) powered vehicles, while their correlation with the number of CNG-powered vehicles was very low, suggesting that reasonable urban traffic controls along with vehicle technology improvements could play an important role in improving urban air quality. PMID:25076527

  17. Roadside Particle Number Distributions and Relationships Between Number Concentrations, Meteorology, and Traffic Along a Northern California Freeway

    NASA Astrophysics Data System (ADS)

    Nanzetta, K.; Holmen, B.

    2002-12-01

    Vehicles are a major source of ultrafine (Dp < 100nm) particles and currently there is no method to estimate particle number emissions of ultrafine and nanoparticles from vehicles operating on the roadway. The ability to estimate particle number has become increasingly important because recent evidence suggests that particle number, not mass, may be the most important predictor of particle-based detrimental health impacts. Roadside particle number distributions (6nm < Dp < 237nm), vehicle counts and meteorological data were measured at two Northern California freeway sites during two seasons to characterize vehicle contributions and meteorological influences on prevailing ultrafine and nanoparticle number concentrations and distributions. Total particle number concentrations measured downwind of the freeway averaged 4.94 /times 10 4 particles/ cm 3 in the fall and 1.96 /times 10 4 particles/cm 3 in the summer and were dominated (over 96 percent ) by ultrafine particles. Downwind total particle number concentrations were an order of magnitude greater than upwind concentrations in the fall season but only 25 percent greater in the summer. Downwind total particle numbers were lower in the summer relative to the fall, likely due to high temperatures and the dilution of roadway aerosols due to variable wind direction. For both seasons, total particle numbers were positively correlated to heavy-duty vehicle volumes ( r/equals 0.456, p < 0.0001) and negatively correlated to temperature (r /equals -0.571, p < 0.0001) and wind speed (r /equals -0.460, p < 0.0001). Downwind particle number distribution modes ranged from 10nm to 40nm with no diurnal pattern. In the summer, upwind particle number distribution modes increased from 10nm in the morning (6:15 AM) to 70nm in the evening (7:00 PM). Greater total particle numbers corresponded to low temperatures, high solar radiation and high humidity conditions; larger modal diameters corresponded to higher temperatures. At high temperatures, nucleation may be suppressed resulting in lower total particle numbers and a shift in the distribution to larger particle sizes. However, during periods of high solar radiation,increases in photochemical oxidation products may trigger nucleation and increased particle numbers. Periods of high solar radiation correspond to warmer temperatures, especially in the summer, therefore these two effects are competing.

  18. Bath Concentration of Anionic Contrast Agents Does Not Affect Their Diffusion and Distribution in Articular Cartilage In Vitro

    PubMed Central

    Jurvelin, Jukka S.; Tiitu, Virpi; Quinn, Thomas M.; Töyräs, Juha

    2013-01-01

    Objective: Differences in contrast agent diffusion reflect changes in composition and structure of articular cartilage. However, in clinical application the contrast agent concentration in the joint capsule varies, which may affect the reliability of contrast enhanced cartilage tomography (CECT). In the present study, effects of concentration of x-ray contrast agents on their diffusion and equilibrium distribution in cartilage were investigated. Design: Full-thickness cartilage discs (d = 4.0 mm, n = 120) were detached from bovine patellae (n = 24). The diffusion of various concentrations of ioxaglate (5, 10, 21, 50 mM) and iodide (30, 60, 126, 300 mM) was allowed only through the articular surface. Samples were imaged with a clinical peripheral quantitative computed tomography scanner before immersion in contrast agent, and after 1, 5, 9, 16, 25, and 29 hours in the bath. Results: Diffusion and partition coefficients were similar between different contrast agent concentrations. The diffusion coefficient of iodide (473 ± 133 µm2/s) was greater (P ≤ 0.001) than that of ioxaglate (92 ± 46 µm2/s). In full-thickness cartilage, the partition coefficient (at 29 h) of iodide (71 ± 5%) was greater (P ≤ 0.02 with most concentrations) than that of ioxaglate (62 ± 6%). Conclusions: Significant differences in partition and diffusion coefficient of two similarly charged (−1) contrast agents were detected, which shows the effect of steric interactions. However, the increase in solute concentration did not increase its partition coefficient. In clinical application, it is important that contrast agent concentration does not affect the interpretation of CECT imaging. PMID:26069649

  19. Seasonal variations in concentrations, distributions, and air-soil exchange fluxes of dioxin-like polychlorinated biphenyls in Shanghai, China.

    PubMed

    Tian, Yajun; Nie, Zhiqiang; He, Jie; Die, Qingqi; Fang, Yanyan; Liu, Feng; Yang, Yufei; Gao, Xingbao; Huang, Qifei

    2016-02-01

    Dioxin-like polychlorinated biphenyl (dl-PCB) concentrations in ambient air and soil in Shanghai, China, were measured to allow seasonal and spatial differences in the dl-PCB concentrations, profiles, distributions, fugacity fractions, and air-soil fluxes to be determined. The toxic equivalent (TEQ) dl-PCB concentrations in the air were higher in summer (mean 9.46 fg m(-3), range 1.32-26.3 fg m(-3)) than in winter (mean 4.57 fg m(-3), range 1.55-10.9 fg m(-3)). The dl-PCB concentrations in air were different in different areas, and the concentrations decreased in the order industrial areas > commercial and residential areas > suburban areas > rural area. The mean dl-PCB concentration in soil was 0.25 pg TEQ g(-1) dry weight (dw) and the range was 0.05-0.90 pg TEQ g(-1) dw. The highest dl-PCB concentration in soil was found in a sample from a commercial/residential area. The dl-PCB fluxes were negative (-216 pg m(-2) h(-1) in summer and -41.1 pg m(-2) h(-1) in winter), and the fugacity fractions were below 0.5, indicating that dl-PCBs in Shanghai are deposited from the air to the soil in all seasons. The net fluxes were higher in summer than in winter, and the deposition fluxes were higher in industrial areas than in other areas in both summer and winter. PMID:26490912

  20. Relationships between stream nitrate concentration and spatially distributed snowmelt in high-elevation catchments of the western U.S.

    NASA Astrophysics Data System (ADS)

    Perrot, Danielle; Molotch, Noah P.; Williams, Mark W.; Jepsen, Steven M.; Sickman, James O.

    2014-11-01

    This study compares stream nitrate (NO3-) concentrations to spatially distributed snowmelt in two alpine catchments, the Green Lakes Valley, Colorado (GLV4) and Tokopah Basin, California (TOK). A snow water equivalent reconstruction model and Landsat 5 and 7 snow cover data were used to estimate daily snowmelt at 30 m spatial resolution in order to derive indices of new snowmelt areas (NSAs). Estimates of NSA were then used to explain the NO3- flushing behavior for each basin over a 12 year period (1996-2007). To identify the optimal method for defining NSAs and elucidate mechanisms underlying catchment NO3- flushing, we conducted a series of regression analyses using multiple thresholds of snowmelt based on temporal and volumetric metrics. NSA indices defined by volume of snowmelt (e.g., snowmelt ≤ 30 cm) rather than snowmelt duration (e.g., snowmelt ≤ 9 days) were the best predictors of stream NO3- concentrations. The NSA indices were better correlated with stream NO3- concentration in TOK (average R2= 0.68) versus GLV4 (average R2= 0.44). Positive relationships between NSA and stream NO3- concentration were observed in TOK with peak stream NO3- concentration occurring on the rising limb of snowmelt. Positive and negative relationships between NSA and stream NO3- concentration were found in GLV4 with peak stream NO3- concentration occurring as NSA expands. Consistent with previous works, the contrasting NO3- flushing behavior suggests that streamflow in TOK was primarily influenced by overland flow and shallow subsurface flow, whereas GLV4 appeared to be more strongly influenced by deeper subsurface flow paths.

  1. Concentration, distribution, and human health risk assessment of endosulfan from a manufacturing facility in Huai'an, China.

    PubMed

    Wang, De-Gao; Alaee, Mehran; Guo, Ming-Xing; Pei, Wei; Wu, Qian

    2014-09-01

    Endosulfan concentrations and its distribution in air, soil, sediment and foodstuffs in the area surrounding a production facility in Huai'an, China were investigated because of its threats to the environment and human health. Air concentrations for endosulfan Ι, endosulfan II and endosulfan sulfate measured in this study were several orders of magnitude higher than those reported previously for this region. Surface soil concentration ranges of endosulfan I, endosulfan II, and endosulfan sulfate were greater than in sediment. Endosulfan II was the greatest contributor to total endosulfan concentrations in both surface sediment and soil followed by endosulfan sulfate and endosulfan Ι. However, a different concentration profile was observed in fish and crop samples, with endosulfan sulfate having the highest concentration followed by endosulfan I and endosulfan II. The concentration of Σendosulfans (endosulfans Ι and II) in soil decreased rapidly with increasing distance from the plant by a factor of 10 within 45 km. Trace amounts of Σendosulfans were observed in deep soil layers which implied that these compounds are transported through the leaching of pore water in soil. This demonstrated that emissions from the manufacturing facility can lead to ground water contamination in the area near the plant. A screening level human health risk assessment of Σendosulfans based on the worst-case scenario was performed for people living in the vicinity of the manufacturing facility. The hazard indices were at least 2 orders of magnitude of <1, indicating no adverse health effects are likely to occur at current exposure levels, and the risk to human health is generally acceptable. PMID:24491393

  2. On the concentration and size distribution of sub-micron aerosol in the Galápagos Islands

    NASA Astrophysics Data System (ADS)

    Sorribas, M.; Gómez Martín, J. C.; Hay, T. D.; Mahajan, A. S.; Cuevas, C. A.; Agama Reyes, M. V.; Paredes Mora, F.; Gil-Ojeda, M.; Saiz-Lopez, A.

    2015-12-01

    During the CHARLEX campaign in the Galápagos Islands, a Scanning Particle Mobility Sizer was deployed on San Cristobal Island in July-August 2011 to carry out size-resolved measurements of the concentration of submicron aerosols. To our knowledge these are the first measurements of aerosol concentrations in this unique environment. The particles with marine origin displayed a tri-modal number size distribution with peak diameters of 0.016 μm, 0.050 μm and 0.174 μm and a cloud-processed intermodal minimum at 0.093 μm. The mean total aerosol number concentration for the marine contribution was 470 ± 160 cm-3. A low particle concentration of 70 ± 50 cm-3 for the nucleation size range was measured, but no evidence of new particle production in the atmospheric marine boundary layer (MBL) was observed. The concentration of the Aitken size mode was found to be related to aerosol entrainment from the free troposphere off the coast of Chile followed by transport within the MBL to the Galápagos Islands. Cloud processing may activate the particles in the Aitken size range, growing through 'in-cloud' sulphate production and increasing the particle concentration in the accumulation size range. The 0.093 μm cloud processed minima suggests that the critical supersaturation at which the particle is activated to a cloud droplet is in the 0.14-0.21% range. The daytime marine particle background concentration was influenced by human activity around the sampling site, as well as by new particle formation triggered by biogenic emissions from the vegetation cover of the island's semiarid lowlands. Effective CCN formation may play a role in the formation and properties of the stratus clouds, which permanently cover the top of the windward side of the islands and establish one of their characteristic climatic bands.

  3. Concentration, distribution, and bioavailability of mercury and methylmercury in sediments of Baltimore Harbor and Chesapeake Bay, Maryland, USA

    SciTech Connect

    Mason, R.P.; Lawrence, A.L.

    1999-11-01

    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.

  4. The simulation of temperature distribution and relative humidity with liquid concentration of 50% using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Yohana, Eflita; Yulianto, Mohamad Endy; Kwang-Hwang, Choi; Putro, Bondantio; Yohanes Aditya W., A.

    2015-12-01

    The study of humidity distribution simulation inside a room has been widely conducted by using computational fluid dynamics (CFD). Here, the simulation was done by employing inputs in the experiment of air humidity reduction in a sample house. Liquid dessicant CaCl2was used in this study to absorb humidity in the air, so that the enormity of humidity reduction occured during the experiment could be obtained.The experiment was conducted in the morning at 8 with liquid desiccant concentration of 50%, nozzle dimension of 0.2 mms attached in dehumidifier, and the debit of air which entered the sample house was 2.35 m3/min. Both in inlet and outlet sides of the room, a DHT 11 censor was installed and used to note changes in humidity and temperature during the experiment. In normal condition without turning on the dehumidifier, the censor noted that the average temperature inside the room was 28°C and RH of 65%.The experiment result showed that the relative humidity inside a sample house was decreasing up to 52% in inlet position. Further, through the results obtained from CFD simulation, the temperature distribution and relative humidity inside the sample house could be seen. It showed that the concentration of liquid desiccant of 50% experienced a decrease while the relative humidity distribution was considerably good since the average RH was 55% followed by the increase in air temperature of 29.2° C inside the sample house.

  5. Improving Simulations of Fine Dust Surface Concentrations over the Western United States by Optimizing the Particle Size Distribution

    SciTech Connect

    Zhang, Li; Kok, Jasper F.; Henze, Daven; Li, Qinbin; Zhao, Chun

    2013-06-28

    To improve estimates of remote contributions of dust to fine particulate matter (PM2.5) in the western United States, new dust particle size distributions (PSDs) based upon scale-invariant fragmentation theory (Kok_PSD) with constraints from in situ measurements (IMP_PSD) are implemented in a chemical transport model (GEOS-Chem). Compared to initial simulations, this leads to reductions in the mass of emitted dust particles with radii <1.8 mm by 40%-60%. Consequently, the root-mean-square error in simulated fine dust concentrations compared to springtime surface observations in the western United States is reduced by 67%-81%. The ratio of simulated fine to coarse PM mass is also improved, which is not achievable by reductions in total dust emissions. The IMP_PSD best represents the PSD of dust transported from remote sources and reduces modeled PM2.5 concentrations up to 5 mg/m3 over the western United States, which is important when considering sources contributing to nonattainment of air quality standards. Citation: Zhang, L., J. F. Kok, D. K. Henze, Q. Li, and C. Zhao (2013), Improving simulations of fine dust surface concentrations over the western United States by optimizing the particle size distribution, Geophys. Res. Lett., 40, 3270-3275, doi:10.1002/grl.50591.

  6. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    PubMed Central

    2009-01-01

    In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N) nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS) mechanism was proposed for the growth of the nanotubes. PMID:20596377

  7. Structures, stability, mechanical and electronic properties of α-boron and α∗-boron

    NASA Astrophysics Data System (ADS)

    He, Chaoyu; Zhong, J. X.

    2013-04-01

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

  8. Concentration, size-distribution and deposition of mineral aerosol over Chinese desert regions

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao Y.; Arimoto, R.; Zhu, G. H.; Chen, T.; Zhang, G. Y.

    1998-09-01

    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 270μg m-3, and the MSDs for the elements were approximately log-normal. On the basis of Al data, the<10μm 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 70μm. 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.

  9. Natural Radioactivity of Boron Added Clay Samples

    NASA Astrophysics Data System (ADS)

    Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

    2011-12-01

    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.

  10. Natural Radioactivity of Boron Added Clay Samples

    SciTech Connect

    Akkurt, I.; Guenoglu, K.; Canakcii, H.; Mavi, B.

    2011-12-26

    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.

  11. Concentration and distribution of Cr and Ni in soils of Talcahuano, Chile.

    NASA Astrophysics Data System (ADS)

    Tume, Pedro; Gonzalez, Elizabeth; King, Robert; Alvarez, Manuel; Roca, Nuria; Bech, Jaume

    2015-04-01

    Urban soils can serve as a recipient for a large amount of trace elements from multiple sources, including, municipal wastes, vehicular emissions and industrial wastes.Several researchers have pointed out the need for a better understanding of urban soils in order to assist in developing strategies to protect urban environments and human health against the longterm accumulation of trace elements.The objectives of this study were to (1) define the background levels of chromium (Cr) and nickel (Ni) in soil of Talcahuano; (2) evaluate the site contaminated by trace metals.In this study, 140 soil plots (420 samples: TS:0-10 cm; SS:10-20 cm and BS:150 cm) located approximately in a 1 km regular grid covering the Talcahuano city(94 square km) have been examined. Soil samples (<2mm fraction) were analyzed by standard methods. Aqua regia digest (ISO 11466.2002) of Cr and Ni were analyzed by Atomic Absorption Spectrophotometry. The median concentrations (mg kg-1) obtained include: Cr 134 (range 66.6 - 657) and Ni 56.1 (26.4 - 137). In weakly developed urban soils, Ni follows the same pattern without any real distinguishing features. Chromium displays slight surface enrichment (Cr content in topsoil (mg kg-1): 145±70; Cr content in basement (mg kg-1): 138 ± 53 ). However, the differences are not significative. Different methods were evaluated in order to facilitate the best diagnosis of contamination. First, the trace metal geochemical background was determined using basic descriptive statistics. The upper limit (Upper Whisker value) of the background content in mg•kg-1is 266 for Cr and 112 for Ni. Secondly, the basic descriptive statistics were then compared with Dutch guidelines, in order to evaluate whether the concentrations measured in soils were abnormally high or not. By comparing the results of the different methods, we estimate that 5% of the soils demonstrate anthropogenic signatures of Cr and Ni.The greatest enrichment anomalies in heavy metals were detected in top soil due to an unauthorized rubbish dump.

  12. Impact of spectral irradiance distribution and temperature on the outdoor performance of concentrator photovoltaic system

    NASA Astrophysics Data System (ADS)

    Husna, Husyira Al; Shibata, Naoki; Sawano, Naoki; Ueno, Seiya; Ota, Yasuyuki; Minemoto, Takashi; Araki, Kenji; Nishioka, Kensuke

    2013-09-01

    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.

  13. The Visualization Method of the 3d Concentration Distribution of Asian Dust in the Google Earth

    NASA Astrophysics Data System (ADS)

    Okuda, W.; Kusaka, T.

    2012-07-01

    The Asian dust (called "Kosa" in Japan) transported from desert areas in the northern China often covers over East Asia in the late winter and spring seasons. In this study, first of all, for dust events observed at various places in Japan on April 1, 2007 and March 21, 2010, the long-range transport simulation of Asian dust from desert areas in the northern China to Japan is carried out. Next, the method for representing 3D dust clouds by means of the image overlay functionality provided in the Google Earth is described. Since it is very difficult to display 3D dust clouds along the curvature of the Earth on the global scale, the 3D dust cloud distributed at the altitude of about 6300m was divided into many thin layers, each of which is the same thickness. After each of layers was transformed to the image layer, each image layer was displayed at the appropriate altitude in the Google Earth. Thus obtained image layers were displayed every an hour in the Google Earth. Finally, it is shown that 3D Asian dust clouds generated by the method described in this study are represented as smooth 3D cloud objects even if we looked at Asian dust clouds transversely in the Google Earth.

  14. Experimental Microbiology of Saturated Salt Solutions and Other Harsh Environments. III. Growth of Salt-Tolerant Penicillium notatum in Boron-Rich Media 1

    PubMed Central

    Roberts, Karen; Siegel, S. M.

    1967-01-01

    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. PMID:6076112

  15. Changes in Concentration and Distribution of Biomarkers in Biodegraded Oils from Dongying Depression, China.

    PubMed

    Chen, Zhonghong; Wang, T-G; Yan, Detian

    2015-10-01

    The alkane fraction of 11 biodegraded oils and five non-biodegraded oils from the Dongying Depression, Bohai Bay Basin, eastern China, were analyzed by gas chromatography-mass spectrometry to investigate the biomarker alteration caused by biodegradation. Results indicated that the concentration of 25-norhopanes was correlated with increased biodegradation. The oil samples showed an increase in the C31 and C32 hopane 22S/(22S + 22R), C29 sterane C2920S/(20S + 20R), and C29ββ/(ββ + αα) thermal maturity parameters in the heavily biodegraded oils. Oleanane was preferentially biodegraded compared with C3017α-hopane, which was preferentially biodegraded compared with C2917α, 21β-norhopane, C30 moretane, and C29 25-norhopane. The selective depletion of C27-C29 steranes followed the order ααα 20R > ααα 20S + αββ 20R > αββ 20S and C27 > C29 > C28, and the diasteranes and C20-C21 steranes were much more resistant to biodegradation than regular C27-C29 steranes. The steranes were generally preferentially biodegraded compared with the hopanes in this study. PMID:26239445

  16. Addition of oxygen to and distribution of oxides in tantalum alloy T-111 at low concentrations

    NASA Technical Reports Server (NTRS)

    Stecura, S.

    1975-01-01

    Oxygen was added at 820 and 990 C at an oxygen pressure of about .0003 torr. The technique permitted predetermined and reproducible oxygen doping of the tantalum alloy (T-111). Based on the temperature dependency of the doping reaction, it was concluded that the initial rates of oxygen pickup are probably controlled by solution of oxygen into the T-111 lattice. Although hafnium oxides are more stable than those of tantalum or tungsten, analyses of extracted residues indicate that the tantalum and tungsten oxides predominate in the as-doped specimens, presumably because of the higher concentrations of tantalum and tungsten in the alloy. However, high-temperature annealing promotes gettering of dissolved oxygen and oxygen from other oxides to form hafnium oxides. Small amounts of tantalum and tungsten oxides were still present after high temperature annealing. Tungsten oxide (WO3) volatilizes slightly from the surface of T-111 at 990 C but not at 820 C. The vaporization of WO3 has no apparent effect on the doping reaction.

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

    USGS Publications Warehouse

    Eisler, R.

    1990-01-01

    Ecological and toxicological aspects of boron (B) in the environment are reviewed, with emphasis on natural resources. Subtopics covered include environmental chemistry, background concentrations, effects, and current recommendations for the protection of living resources. Boron is not now considered essential in mammalian nutrition, although low dietary levels protect against fluorosis and bone demineralization. Excessive consumption (i.e., >1,000 mg B/kg diet, >15 mg B/kg body weight daily, >1.0 mg B/L drinking water, or >210 mg B/kg body weight in a single dose) adversely affects growth, survival, or reproduction in sensitive mammals. Boron and its compounds are potent teratogens when applied directly to the mammalian embryo, but there is no evidence of mutagenicity or carcinogenicity. Boron`s unique affinity for cancerous tissues has been exploited in neutron capture radiation therapy of malignant human brain tumors. Current boron criteria recommended for the protection of sensitive species include <0.3 mg B/L in crop irrigation waters, <1.0 mg B/L for aquatic life, <5.0 mg B/L in livestock drinking waters, <30 mg B/kg in waterfowl diets, and <100 mg B/kg in livestock diets.

  18. The Use of Neutron Analysis Techniques for Detecting The Concentration And Distribution of Chloride Ions in Archaeological Iron

    PubMed Central

    Watkinson, D; Rimmer, M; Kasztovszky, Z; Kis, Z; Maróti, B; Szentmiklósi, L

    2014-01-01

    Chloride (Cl) ions diffuse into iron objects during burial and drive corrosion after excavation. Located under corrosion layers, Cl is inaccessible to many analytical techniques. Neutron analysis offers non-destructive avenues for determining Cl content and distribution in objects. A pilot study used prompt gamma activation analysis (PGAA) and prompt gamma activation imaging (PGAI) to analyse the bulk concentration and longitudinal distribution of Cl in archaeological iron objects. This correlated with the object corrosion rate measured by oxygen consumption, and compared well with Cl measurement using a specific ion meter. High-Cl areas were linked with visible damage to the corrosion layers and attack of the iron core. Neutron techniques have significant advantages in the analysis of archaeological metals, including penetration depth and low detection limits. PMID:26028670

  19. Distribution and concentration of cholesteryl ester transfer protein in plasma of normolipemic subjects.

    PubMed

    Marcel, Y L; McPherson, R; Hogue, M; Czarnecka, H; Zawadzki, Z; Weech, P K; Whitlock, M E; Tall, A R; Milne, R W

    1990-01-01

    A MAb (TP-2) directed against human cholesteryl ester transfer protein (CETP) has been applied to the development of a competitive solid-phase RIA. Experiments with immobilized CETP have shown that upon incubation with plasma or HDL in the presence of Tween (0.05%) apo A-I (but not apo A-II) binds to CETP while TP-2 binding to CETP is concomitantly decreased. With high detergent concentration (0.5% Triton), the interference is eliminated and a specific RIA in which all plasma CETP fractions have the same affinity can be obtained. Plasma levels of CETP, apo A-I, lipids, and lipoproteins were measured in 50 normolipemic, healthy subjects of both sexes. CETP levels varied nearly fourfold with a mean value of 1.7 micrograms/ml. CETP was positively correlated only with apo A-I (r = 0.38) and HDL-triglyceride (r = 0.39). In 29 other normolipemic subjects, where several apolipoproteins were also measured, significant correlations of CETP with apo A-I (0.41), apo E (0.43), and HDL-cholesterol (0.41) were observed, but there was no significant relationship between CETP and either apo A-II, B, or D. In other experiments CETP was shown to be present mostly in HDL3 and VHDL, to display exclusively an alpha 2-electrophoretic migration, and to occur within discrete particles ranging in size from 129 to 154 kD. In conclusion, the association of CETP with apo A-I-containing lipoproteins probably explains the correlation between CETP and apo A-I levels. The relationship between CETP and apo E suggests either a common metabolism or a specific cooperative role in cholesterol ester transport for these proteins. PMID:2295691

  20. Boron isotopic compositions of some boron minerals

    SciTech Connect

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

    1989-12-01

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

  1. Conductivities and Seebeck coefficients of boron carbides: Softening bipolaron hopping

    SciTech Connect

    Aselage, T. L.; Emin, D.; McCready, S. S.

    2001-08-01

    The electrical conductivities and Seebeck coefficients of boron carbides B{sub 12+x}C{sub 3-x} with 0.06{approx}concentration. The preexponential factors of the conductivity exhibit a nonmonotonic dependence on x, peaking near x=1. These results are consistent with a previously proposed model based on holes forming singlet bipolarons on the boron carbide B{sub 11}C icosahedra. At low temperature, the boron carbide conductivities are non-Arrhenius with a temperature dependence that is a strong function of the composition x. This strong sensitivity to composition indicates that percolation effects, arising from boron carbides having carbon atoms in inequivalent locations, influence the conductivity at low temperature. With x holes per unit cell, boron carbides have very large Seebeck coefficients that depend only weakly on x. The magnitudes and temperature dependences of the Seebeck coefficients are consistent with large contributions from carrier-induced softening of local vibrations. Softening effects can be exceptionally large when singlet bipolarons are stabilized among degenerate electronic energy levels by their softening of symmetry-breaking vibrations: ''softening bipolarons.'' The boron carbide transport properties are generally consistent with those expected of softening bipolarons. Finally, two high-temperature effects are observed in the boron carbide conductivities. The conductivities of samples having high carrier densities, x{approx}1, are suppressed above 700 K. This suppression can arise when the rapid hopping of nearby carriers disrupts the energy coincidence required for a carrier's hop. At even higher temperatures, a sharp increase in the boron carbide conductivities ({sigma}{proportional_to}T{sup 4}) suggests a radiation-induced excitation of mobile charge carriers.

  2. Polarization control of an infrared silicon light-emitting diode by dressed photons and analyses of the spatial distribution of doped boron atoms

    NASA Astrophysics Data System (ADS)

    Kawazoe, Tadashi; Nishioka, Katsuhiro; Ohtsu, Motoichi

    2015-12-01

    This paper reports the fabrication of a polarization-controlled infrared LED fabricated by dressed-photon-phonon (DPP)-assisted annealing of a bulk Si crystal. For the DPP-assisted annealing, linearly polarized infrared light with a wavelength of 1.342 μm was made normally incident on the top surface of the crystal. The photon energy at the peak of the emitted light spectrum of the fabricated LED was close to that of the light irradiated during the DPP-assisted annealing. A degree of polarization of as large as 0.07 was obtained. The spatial distribution of the doped B atoms in the fabricated LED was measured, and the following findings were obtained: (1) B atoms formed pairs in which the separation between the two B atoms was three times the lattice constant of the Si crystal; and (2) the B atom pairs were apt to orient along the direction perpendicular to the propagation direction and to the polarization direction of the light irradiated during the DPP-assisted annealing. Based on these findings (1) and (2), photon breeding was confirmed with respect to photon energy and spin, respectively.

  3. Method of fabricating boron containing coatings

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1999-01-01

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

  4. Method of fabricating boron containing coatings

    DOEpatents

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

    1999-04-27

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

  5. Airborne DOAS measurements in Arctic: vertical distributions of aerosol extinction coefficient and NO2 concentration

    NASA Astrophysics Data System (ADS)

    Merlaud, A.; van Roozendael, M.; Theys, N.; Fayt, C.; Hermans, C.; Quennehen, B.; Schwarzenboeck, A.; Ancellet, G.; Pommier, M.; Pelon, J.; Burkhart, J.; Stohl, A.; de Mazière, M.

    2011-05-01

    We report airborne differential optical absorption spectroscopy (DOAS) measurements of aerosol extinction and NO2 tropospheric profiles performed off the North coast of Norway in April 2008. The DOAS instrument was installed on the Safire ATR-42 aircraft during the POLARCAT-France spring campaign and recorded scattered light spectra in near-limb geometry using a scanning telescope. We use O4 slant column measurements to derive the aerosol extinction at 360 nm. Regularization is based on the maximum a posteriori solution, for which we compare a linear and a logarithmic approach. The latter inherently constrains the solution to positive values and yields aerosol extinction profiles more consistent with independently measured size distributions. Two soundings are presented, performed on 8 April 2008 above 71° N, 22° E and on 9 April 2008 above 70° N, 17.8° E. The first profile shows aerosol extinction and NO2 in the marine boundary layer with respective values of 0.04±0.005 km-1 and 1.9±0.3 × 109 molec cm-3. A second extinction layer of 0.01±0.003 km-1 is found at 4 km altitude. During the second sounding, clouds prevented us to retrieve profile parts under 3 km altitude but a layer with enhanced extinction (0.025±0.005 km-1) and NO2 (1.95±0.2 × 109 molec cm-3) is clearly detected at 4 km altitude. From CO and ozone in-situ measurements complemented by back-trajectories, we interpret the measurements in the free troposphere as, for the first sounding, a mix between stratospheric and polluted air from Northern Europe and for the second sounding, polluted air from Central Europe containing NO2. Considering the boundary layer measurements of the first flight, modeled source regions indicate closer sources, especially the Kola Peninsula smelters, which can explain the NO2 enhancement not correlated with a CO increase at the same altitude.

  6. Concentration and Distribution of Well Drilling in the Amargosa Desert Area of Southern Nevada

    NASA Astrophysics Data System (ADS)

    Lee, M. P.; Gross, A. J.; Coleman, N. M.

    2002-05-01

    The earliest sources of fresh water supply in the Amargosa Desert area of Southern Nevada were the abundant, naturally occurring (cold) springs. They initially sustained the indigenous Native American populations and later, Euro-American miners, farmers, and ranchers. Prior to 1900, the many local springs and a few (mostly shallow) hand-dug wells were the principal sources of water supply. The first hand-dug well in the area was the Franklin well; it was dug in 1852 for workers performing a survey of the California-Nevada State line. The first mechanically bored wells were drilled for local railroads, along their respective alignments, sometime between 1905-07. About 1917, the first irrigation well in the Amargosa Desert area was drilled for an experimental farm operated by the Tonopah and Tidewater Railroad. In the late 1940s-early 1950s, permanent interest in the area was established, in large measure because of a Federally sponsored desert reclamation program. For the period 1900-1999, a preliminary evaluation of publicly available information (collected principally by the State Engineer) indicates that more than 950 boreholes were drilled in the Amargosa Desert area. Almost half of these boreholes were drilled in the last 20 years. Forty-two percent of the boreholes were drilled to supply fresh drinking water; 26 percent were in support of irrigated agriculture; 21 percent of the wells were drilled for some non-water supply related purpose - ground-water monitoring and testing; and 11 percent were drilled to supply water for commercial or unspecified applications. Most of the well drilling has been concentrated in a parcel of land about 30-40 kilometers south of the proposed geologic repository at Yucca Mountain, Nevada. Most wells have been generally drilled to depths less than 30 meters (100 feet), although deeper wells are uncommon. The main reason is that drilling is expensive and the profitability of finding and extracting potable water, in sufficient quantity, generally declines with depth. However, during the last two decades, there has been a general decline in drilling for irrigation. Designation of local aquifers in the area as "protected" in 1979 has favored new well-permitting for residential or commercial uses. Moreover, in the 1990s, local farmers were required to forfeit unused water rights and these rights have been reallocated to new, non-farming residents by the State Engineer in Nevada's Department of Conservation and Natural Resources. Nevertheless, the general decline in irrigation permitting for farming over the last several decades most likely has more to do with the physical and/or economic factors that have historically controlled local farming rather than with recent water availability issues.

  7. Investigation of Hard Boron Rich Solids: Osmium Diboride and β-Rhombohedral Boron

    NASA Astrophysics Data System (ADS)

    Hebbache, M.; Živković, D.

    Recently, we succeeded in synthesizing three osmium borides, i.e., OsB1.1, Os2B3 and OsB2. Up to date, almost nothing is known about the physical properties of these materials. Microhardness measurements show that OsB2 is extremely hard. Ab initio calculations show that it is due to formation of covalent bonds between boron atoms. OsB2 is also a low compressibility material. It can be used for hard coatings. The β-rhombohedral polymorph of boron is the second hardest elemental crystal (H ≈ 33 GPa). It is also very light and a p-type semiconductor. In early 1970s, it has been shown that the doping of boron with 3d transition elements enhances its hardness by about 25%. We predict that, in general, heavily doped samples MBx, with x ≤ 31 or equivalently a dopant concentration larger than 3.2 at.%, should be ultrahard, i.e., H > 43 GPa. The relevant dopants M are Al, Cu, Sc, Mn, Mg and Li. In addition to these properties, boron-rich materials have a very low volatility, a high chemical inertness and high melting point. They are suitable for applications under extreme conditions and thermoelectric equipment.

  8. [Concentration and distribution of fluorine in hen's eggs as an aspect of selected biological parameters].

    PubMed

    Machali?ski, B

    1996-01-01

    The actual paper presents the method and results of studies concerning the content and decomposition of fluorine compounds in the component structures of eggs and in the bone system of a domestic hen, as well as its progeny under conditions of increased content of these compounds in the drinking water. The objective of the paper has been: 1) determining the effect of environmental contamination (NaF in drinking water) exerted on the presence of fluorine in eggs, 2) defining the distribution of fluorine in component structures of the egg, 3) studying the fluorine effect on selected physical parameters of eggs, 4) determination of fluorine content in tibial bones of laying hens, after receiving NaF in drinking water, and to compare the tibial bone composition in hens and their progeny with control groups, 5) analyzing the share of fluorine compounds in the construction of skeleton and beaks of chicks. The conceptions of the work were elaborated on the basis of results stemming from an accomplished experimental breeding of domestic hens in a semi-intensive system. The experiment proceeded 4 weeks. A part of eggs obtained by breeding was designed for hatching. Due to the requirements associated with analyzing the skeleton, all the experimental birds, including the chicks, were assigned for further analyses. The material, obtained in this way, (bones of hens, chicks, eggs) was subsequently subjected to detailed studies. According to the conceptions of the paper the selected physical parameters of eggs were studied, therein resistance tests, using specialized apparatuses. Fluoride was determined potentiometrically, by applying fluoride ion selective electrode, while the metallic elements by aid of atomic spectrophotometer (Tab. 1-5, Fig. 1). Finally, the following conclusions were presented, namely: 1. The egg shell in hens plays an essential role in binding fluorine compounds and constitutes one of the means of their fast elimination from the organism. 2. Egg shells may provide an easily accessible bioindicator for the exposure of birds to fluorine compound, particularly with regard to a given species. 3. Moderately increased fluorine content in the shells of eggs fails to influence their thickness and does not cause any changes in their resistance to decay. 4. In conditions of increased exposure of hens to fluorine compounds, no elevation in the accumulation of this element was disclosed in the substance, which is evidence that there is a lack of apparent influence of local contamination by emissions of fluorine compounds exerted on nutritional usefulness of eggs. 5. Comparison of fluorine content in the bones of chicks, stemming from hens being given water with NaF to drink, with control hens points to a significant rise in fluoride accumulation in progeny of hens, exposed to sodium fluoride action. That may have a negative influence on their correct development. PMID:9199123

  9. Titanium reinforced boron polyimide composite

    NASA Technical Reports Server (NTRS)

    Clark, G. A.

    1972-01-01

    Program involves development of process technique for boron-polyimide prepeg, lay-up and curing procedures for prepegs when processed under vacuum bag pressure, and development and evaluation of titanium hard points for smooth transition of loads from titanium attach points into boron reinforced body of structure.

  10. Boron Clusters Come of Age

    ERIC Educational Resources Information Center

    Grimes, Russell N.

    2004-01-01

    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…

  11. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  12. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  13. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  14. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  15. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  16. 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

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m 3)...

  17. 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, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  18. 40 CFR Table F-4 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Coarse Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  19. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Estimated Mass Concentration... Concentration Measurement of PM2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m3) Estimated...

  20. 40 CFR Table F-6 to Subpart F of... - Estimated Mass Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Estimated Mass Concentration... Concentration Measurement of PM 2.5 for Idealized Fine Aerosol Size Distribution Particle Aerodynamic Diameter (µm) Test Sampler Fractional Sampling Effectiveness Interval Mass Concentration (µg/m 3)...

  1. Spatial distribution of the electrical potential and ion concentration in the downstream area of atmospheric pressure remote plasma

    NASA Astrophysics Data System (ADS)

    Mishin, M. V.; Protopopova, V. S.; Uvarov, A. A.; Alexandrov, S. E.

    2014-10-01

    This paper presents the results from an experimental study of the ion flux characteristics behind the remote plasma zone in a vertical tube reaction chamber for atmospheric pressure plasma enhanced chemical vapor deposition. Capacitively coupled radio frequency plasma was generated in pure He and gas mixtures: He-Ar, He-O2, He-TEOS. We previously used the reaction system He-TEOS for the synthesis of self-assembled structures of silicon dioxide nanoparticles. It is likely that the electrical parameters of the area, where nanoparticles have been transported from the synthesis zone to the substrate, play a significant role in the self-organization processes both in the vapor phase and on the substrate surface. The results from the spatial distribution of the electrical potential and ion concentration in the discharge downstream area measured by means of the external probe of original design and the special data processing method are demonstrated in this work. Positive and negatives ions with maximum concentrations of 106-107 cm-3 have been found at 10-80 mm distance behind the plasma zone. On the basis of the revealed distributions for different gas mixtures, the physical model of the observed phenomena is proposed. The model illustrates the capability of the virtual ion emitter formation behind the discharge gap and the presence of an extremum of the electrical potential at the distance of approximately 10-2-10-1 mm from the grounded electrode.

  2. Blind Deconvolution for Distributed Parameter Systems with Unbounded Input and Output and Determining Blood Alcohol Concentration from Transdermal Biosensor Data.

    PubMed

    Rosen, I G; Luczak, Susan E; Weiss, Jordan

    2014-03-15

    We develop a blind deconvolution scheme for input-output systems described by distributed parameter systems with boundary input and output. An abstract functional analytic theory based on results for the linear quadratic control of infinite dimensional systems with unbounded input and output operators is presented. The blind deconvolution problem is then reformulated as a series of constrained linear and nonlinear optimization problems involving infinite dimensional dynamical systems. A finite dimensional approximation and convergence theory is developed. The theory is applied to the problem of estimating blood or breath alcohol concentration (respectively, BAC or BrAC) from biosensor-measured transdermal alcohol concentration (TAC) in the field. A distributed parameter model with boundary input and output is proposed for the transdermal transport of ethanol from the blood through the skin to the sensor. The problem of estimating BAC or BrAC from the TAC data is formulated as a blind deconvolution problem. A scheme to identify distinct drinking episodes in TAC data based on a Hodrick Prescott filter is discussed. Numerical results involving actual patient data are presented. PMID:24707065

  3. Characterization of urban pollutant emission fluxes and ambient concentration distributions using a mobile laboratory with rapid response instrumentation.

    PubMed

    Herndon, Scott C; Jayne, John T; Zahniser, Mark S; Worsnop, Douglas R; Knighton, Berk; Alwine, Eugene; Lamb, Brian K; Zavala, Miguel; Nelson, David D; McManus, J Barry; Shorter, Joanne H; Canagaratna, Manjula R; Onasch, Timothy B; Kolb, Charles E

    2005-01-01

    A large and increasing fraction of the planet's population lives in megacities, especially in the developing world. These large metropolitan areas generally have very high levels of both gaseous and particulate air pollutants that have severe impacts on human health, ecosystem viability, and climate on local, regional, and even continental scales. Emissions fluxes and ambient pollutant concentration distributions are generally poorly characterized for large urban areas even in developed nations. Much less is known about pollutant sources and concentration patterns in the faster growing megacities of the developing world. New methods of locating and measuring pollutant emission sources and tracking subsequent atmospheric chemical transformations and distributions are required. Measurement modes utilizing an innovative van based mobile laboratory equipped with a suite of fast response instruments to characterize the complex and "nastier" chemistry of the urban boundary layer are described. Instrumentation and measurement strategies are illustrated with examples from the Mexico City and Boston metropolitan areas. It is shown that fleet average exhaust emission ratios of formaldehyde (HCHO), acetaldehyde (CH3CHO) and benzene (C6H6) are substantial in Mexico City, with gasoline powered vehicles emitting higher levels normalized by fuel consumption. NH3 exhaust emissions from newer light duty vehicles in Mexico City exceed levels from similar traffic in Boston. A mobile conditional sampling air sample collection mode designed to collect samples from intercepted emission plumes for later analysis is also described. PMID:16161792

  4. Boron removal from aqueous solutions using alginate gel beads in fixed-bed systems

    PubMed Central

    Demey-Cedeño, Hary; Ruiz, Montserrat; Barron-Zambrano, Jesús Alberto; Sastre, Ana Maria

    2014-01-01

    Background A column sorption study was carried out using calcium alginate gel beads as adsorbent for the removal of boron from aqueous solutions. The breakthrough curve was obtained as a function of pH, initial concentration of boron, feed flow rate, adsorbent mass and column diameter. The breakthrough capacity values and adsorption percentage of calcium alginate gel for boron were calculated. Column data obtained at different conditions were described using the Adams–Bohart model and bed-depth service time (BDST), derived from the Adams–Bohart equation to predict breakthrough curves and to determine the characteristic column parameters required for process design. Results The maximum adsorption percentage of boron on calcium alginate gel beads using an initial concentration of boron of 50 mg L−1 at pH 11 and room temperature (20±1°C) was calculated to be 55.14%. Conclusion The results indicated that calcium alginate can be used in a continuous packed-bed column for boron adsorption. The optimal conditions for boron adsorption were obtained at high pH, higher initial boron concentration, increased column depth and lower flow velocity. © 2014 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:25821332

  5. Process for producing boron nitride

    SciTech Connect

    Parrish, L.N.; Chase, C.C.

    1988-06-07

    A process for producing boron nitride is described which comprises mixing boron oxide, orthoboric acid and melamine to form a reaction composition which comprises from about 45 to about 50 weight percent, based on the weight of the reaction composition, of melamine and from about 50 to about 55 weight percent, based on the weight of the reaction composition, of a combination of boron oxide and orthoboric acid. The weight ratio of boron oxide to orthoboric acid is from about 3:1 to about 4:1; and heating the composition to temperature of about 700/sup 0/C to about 1200/sup 0/C under a non-oxidizing atmosphere to form boron nitride.

  6. Distribution of microbial arsenic reduction, oxidation and extrusion genes along a wide range of environmental arsenic concentrations.

    PubMed

    Escudero, Lorena V; Casamayor, Emilio O; Chong, Guillermo; Pedrós-Alió, Carles; Demergasso, Cecilia

    2013-01-01

    The presence of the arsenic oxidation, reduction, and extrusion genes arsC, arrA, aioA, and acr3 was explored in a range of natural environments in northern Chile, with arsenic concentrations spanning six orders of magnitude. A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms. Enterobacterial related arsC genes appeared only in the environments with the lowest As concentration, while Firmicutes-like genes were present throughout the range of As concentrations. The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied. The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient. Sediment samples had a higher number of arsenic related genes than water samples. Considering the results of the bacterial community composition available for these samples, the higher microbial phylogenetic diversity of microbes inhabiting the sediments may explain the increased number of genetic resources found to cope with arsenic. Overall, the environmental distribution of arsenic related genes suggests that the occurrence of different ArsC families provides different degrees of protection against arsenic as previously described in laboratory strains, and that the glutaredoxin (Grx)-linked arsenate reductases related to Enterobacteria do not confer enough arsenic resistance to live above certain levels of As concentrations. PMID:24205341

  7. Distribution of Microbial Arsenic Reduction, Oxidation and Extrusion Genes along a Wide Range of Environmental Arsenic Concentrations

    PubMed Central

    Escudero, Lorena V.; Casamayor, Emilio O.; Chong, Guillermo; Pedrós-Alió, Carles; Demergasso, Cecilia

    2013-01-01

    The presence of the arsenic oxidation, reduction, and extrusion genes arsC, arrA, aioA, and acr3 was explored in a range of natural environments in northern Chile, with arsenic concentrations spanning six orders of magnitude. A combination of primers from the literature and newly designed primers were used to explore the presence of the arsC gene, coding for the reduction of As (V) to As (III) in one of the most common detoxification mechanisms. Enterobacterial related arsC genes appeared only in the environments with the lowest As concentration, while Firmicutes-like genes were present throughout the range of As concentrations. The arrA gene, involved in anaerobic respiration using As (V) as electron acceptor, was found in all the systems studied. The As (III) oxidation gene aioA and the As (III) transport gene acr3 were tracked with two primer sets each and they were also found to be spread through the As concentration gradient. Sediment samples had a higher number of arsenic related genes than water samples. Considering the results of the bacterial community composition available for these samples, the higher microbial phylogenetic diversity of microbes inhabiting the sediments may explain the increased number of genetic resources found to cope with arsenic. Overall, the environmental distribution of arsenic related genes suggests that the occurrence of different ArsC families provides different degrees of protection against arsenic as previously described in laboratory strains, and that the glutaredoxin (Grx)-linked arsenate reductases related to Enterobacteria do not confer enough arsenic resistance to live above certain levels of As concentrations. PMID:24205341

  8. Functionalized boron nitride nanotubes

    DOEpatents

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

    2014-04-22

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

  9. Azomethine H colorimetric method for determining dissolved boron in water

    USGS Publications Warehouse

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

    1979-01-01

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

  10. Boron containing multilayer coatings and method of fabrication

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1997-01-01

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

  11. The influences of cultivation setting on inflorescence lipid distributions, concentrations, and carbon isotope ratios of Cannabis sp.

    PubMed

    Tipple, Brett J; Hambach, Bastian; Barnette, Janet E; Chesson, Lesley A; Ehleringer, James R

    2016-05-01

    While much is known about how the growth environment influences many aspects of floral morphology and physiology, little is known about how the growth setting influences floral lipid composition. We explored variations in paraffin wax composition in Cannabis sp., a cash crop grown both indoors and outdoors across the United States today. Given an increased focus on regulation of this crop, there are additional incentives to certify the setting of Cannabis cultivation. To understand the impacts of the growth environment, we studied distributions, concentrations, and carbon isotope ratios of n-alkanes isolated from Cannabis sp. inflorescences to assess if variations within these lipid parameters were related to known growth settings of specimens seized by federal agents. We found that Cannabis plants cultivated under open-field settings had increased inflorescence paraffin wax abundances and greater production of lower molecular weight n-alkanes relative to plants grown in enclosed environments. Further, the carbon isotope ratios of n-C29 from Cannabis plants grown in enclosed environments had relatively lower carbon isotope (δ(13)C) values compared to plants from open-field environments. While this set of observations on seized plant specimens cannot address the particular driver behind these observations, we posit that (a) variations in irradiance and/or photoperiod may influence the distribution and concentration of inflorescence lipids, and (b) the δ(13)C value of source CO2 and lipid concentration regulates the δ(13)C values of inflorescence n-C29 and bulk Cannabis plant materials. Nonetheless, by using a cultivation model based on δ(13)C values of n-C29, the model correctly identified the growth environment 90% of time. We suggest that these lipid markers may be used to trace cultivation methods of Cannabis sp. now and become a more powerful marker in the future, once the mechanism(s) behind these patterns is uncovered. PMID:27045381

  12. [Residue Concentration and Distribution Characteristics of Perfluorinated Compounds in Surface Water from Qiantang River in Hangzhou Section].

    PubMed

    Zhang, Ming; Tang, Fang-liang; Yu, Ya-yun; Xu, Jian-fen; Li, Hua; Wu, Min-hua; Zhang, Wei; Pan, Jian-yang

    2015-12-01

    This study studied the pollution characteristics of perfluorinated compounds (PFCs) in Qiantang River in Hangzhou section (QR). Surface water samples, collected in July 2014 and January 2015 from 14 sites in QR were analyzed for 16 PFCs. All samples were prepared by solid-phase extraction with Oasis WAX cartridges and analyzed using the ultra performance liquid chromatography interfaced to tandem mass spectrometry ( UPLC-MS/MS). The results showed that 8 medium-and short-chain PFCs including C₄ and C₈ perfluorinated sulfonates (PFSAs) and C₄-C₉ perfluorinated carboxylic acids (PFCAs) were detected in the surface waters. The total concentrations of PFCs ranged from 0.98 to 609 ng · L⁻¹, while perfluorooctanoic acid (PFOA) dominated, with range of 0.59-538 ng L⁻¹, and perfluorooctane sulfonate (PFOS) was detected at lower levels, ranging from 0 to 2.48 ng · L⁻¹. The spatial distribution of PFCs varied, and the pollutant concentrations at the sampling sites located in upstream of the river such as Lanjiangkou and Jiangjunyan were relatively high, PFCs concentration showed a decreasing trend from the upstream to the downstream. According to the ratio of feature components, PFCs in surface water of QR originated largely from the input of direct sewage emissions. Taken together, the PFCs pollution was highly correlated with the upstream of Qiantang River valley's industry distribution, and most of the mass load in the investigated river was attributed to upstream running water with a minor influence from the wastewater discharges along the r