Sample records for nanometer-sized diamond particle

  1. Nanometer-Sized Diamond Particle as a Probe for Biolabeling

    PubMed Central

    Chao, Jui-I.; Perevedentseva, Elena; Chung, Pei-Hua; Liu, Kuang-Kai; Cheng, Chih-Yuan; Chang, Chia-Ching; Cheng, Chia-Liang

    2007-01-01

    A novel method is proposed using nanometer-sized diamond particles as detection probes for biolabeling. The advantages of nanodiamond's unique properties were demonstrated in its biocompatibility, nontoxicity, easily detected Raman signal, and intrinsic fluorescence from its natural defects without complicated pretreatments. Carboxylated nanodiamond's (cND's) penetration ability, noncytotoxicity, and visualization of cND-cell interactions are demonstrated on A549 human lung epithelial cells. Protein-targeted cell interaction visualization was demonstrated with cND-lysozyme complex interaction with bacteria Escherichia coli. It is shown that the developed biomolecule-cND complex preserves the original functions of the test protein. The easily detected natural fluorescent and Raman intrinsic signals, penetration ability, and low cytotoxicity of cNDs render them promising agents in multiple medical applications. PMID:17513352

  2. Digital image processing of nanometer-size metal particles on amorphous substrates

    NASA Technical Reports Server (NTRS)

    Soria, F.; Artal, P.; Bescos, J.; Heinemann, K.

    1989-01-01

    The task of differentiating very small metal aggregates supported on amorphous films from the phase contrast image features inherently stemming from the support is extremely difficult in the nanometer particle size range. Digital image processing was employed to overcome some of the ambiguities in evaluating such micrographs. It was demonstrated that such processing allowed positive particle detection and a limited degree of statistical size analysis even for micrographs where by bare eye examination the distribution between particles and erroneous substrate features would seem highly ambiguous. The smallest size class detected for Pd/C samples peaks at 0.8 nm. This size class was found in various samples prepared under different evaporation conditions and it is concluded that these particles consist of 'a magic number' of 13 atoms and have cubooctahedral or icosahedral crystal structure.

  3. Depositing nanometer-sized particles of metals onto carbon allotropes

    NASA Technical Reports Server (NTRS)

    Delozier, Donavon M. (Inventor); Fallbach, Michael J. (Inventor); Smith, Joseph G. (Inventor); Watson, Kent A. (Inventor); Ghose, Sayata (Inventor); Connell, John W. (Inventor)

    2010-01-01

    A process for depositing nanometer-sized metal particles onto a substrate in the absence of aqueous solvents, organic solvents, and reducing agents, and without any required pre-treatment of the substrate, includes preparing an admixture of a metal compound and a substrate by dry mixing a chosen amount of the metal compound with a chosen amount of the substrate; and supplying energy to the admixture in an amount sufficient to deposit zero valance metal particles onto the substrate. This process gives rise to a number of deposited metallic particle sizes which may be controlled. The compositions prepared by this process are used to produce polymer composites by combining them with readily available commodity and engineering plastics. The polymer composites are used as coatings, or they are used to fabricate articles, such as free-standing films, fibers, fabrics, foams, molded and laminated articles, tubes, adhesives, and fiber reinforced articles. These articles are well-suited for many applications requiring thermal conductivity, electrical conductivity, antibacterial activity, catalytic activity, and combinations thereof.

  4. Effect of graphite particle size and content on the formation mechanism of detonation polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Tong, Y.; Cao, Y.; Liu, R.; Shang, S. Y.; Huang, F. L.

    2018-03-01

    The formation mechanism of detonation polycrystalline diamond (DPD) generated from the detonation of a mixed RDX/graphite explosive is investigated. It is found experimentally that the DPD conversion rate decreases with both the content and the particle size of the graphite. Moreover, the particle sizes of the generated DPD powder are analyzed, which shows that, with the decrease in the graphite particle size, the mean number diameter of DPD decreases, but the mean volume diameter increases. In addition, with the help of scanning electron microscopy, it is observed that the in situ phase change occurs in the graphite particles, by which the small particles combine to form numerous large DPD particles. Based on both the experimental data and the classical ZND detonation model, we divide such a DPD synthesis process into two stages: In the first stage, the in situ phase change from graphite to diamond is dominant, supplemented by some coalescence growth at high pressure and temperature, which is affected mainly by the detonation performance of the mixed explosive under consideration. In the second stage, the graphitization of DPD caused by the residual heat is dominant, which is affected mainly by the unloading rate of the particle temperature.

  5. Diamond structure cannot be stable in nm-sized particles.

    PubMed

    Batsanov, Stepan S

    2014-12-01

    The observed and calculated densities of nanodiamond cannot be reconciled, and the stability of diamond structure explained, if nanodiamond is regarded as a form of pure carbon. The surface-terminating hydrogen and functional groups are an integral part in the stability of these particles which therefore need not be as inert and non-toxic as bulk diamond, with important implications for nanomedicine.

  6. Nano-sized and micro-sized polystyrene particles affect phagocyte function

    PubMed Central

    Prietl, B.; Meindl, C.; Roblegg, E.; Pieber, T. R.; Lanzer, G.; Fröhlich, E.

    2015-01-01

    Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes. PMID:24292270

  7. Nano-sized and micro-sized polystyrene particles affect phagocyte function.

    PubMed

    Prietl, B; Meindl, C; Roblegg, E; Pieber, T R; Lanzer, G; Fröhlich, E

    2014-02-01

    Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes.

  8. Size-dependent reactivity of diamond nanoparticles.

    PubMed

    Williams, Oliver A; Hees, Jakob; Dieker, Christel; Jäger, Wolfgang; Kirste, Lutz; Nebel, Christoph E

    2010-08-24

    Photonic active diamond nanoparticles attract increasing attention from a wide community for applications in drug delivery and monitoring experiments as they do not bleach or blink over extended periods of time. To be utilized, the size of these diamond nanoparticles needs to be around 4 nm. Cluster formation is therefore the major problem. In this paper we introduce a new technique to modify the surface of particles with hydrogen, which prevents cluster formation in buffer solution and which is a perfect starting condition for chemical surface modifications. By annealing aggregated nanodiamond powder in hydrogen gas, the large (>100 nm) aggregates are broken down into their core ( approximately 4 nm) particles. Dispersion of these particles into water via high power ultrasound and high speed centrifugation, results in a monodisperse nanodiamond colloid, with exceptional long time stability in a wide range of pH, and with high positive zeta potential (>60 mV). The large change in zeta potential resulting from this gas treatment demonstrates that nanodiamond particle surfaces are able to react with molecular hydrogen at relatively low temperatures, a phenomenon not witnessed with larger (20 nm) diamond particles or bulk diamond surfaces.

  9. Osteomyelitis Treatment with Nanometer-Sized Hydroxyapatite Particles as a Delivery Vehicle for a Ciprofloxacin- Bisphosphonate Conjugate; New Fluoroquinolone-Bisphosphonate Derivatives Show Similar Binding Affinity to Hydroxyapatite and Improved Antibacterial Activity Against Drug-Resistant Pathogens

    DTIC Science & Technology

    2008-12-01

    1 OSTEOMYELITIS TREATMENT WITH NANOMETER-SIZED HYDROXYAPATITE PARTICLES AS A DELIVERY VEHICLE FOR A CIPROFLOXACIN- BISPHOSPHONATE CONJUGATE; NEW...FLUOROQUINOLONE-BISPHOSPHONATE DERIVATIVES SHOW SIMILAR BINDING AFFINITY TO HYDROXYAPATITE AND IMPROVED ANTIBACTERIAL ACTIVITY AGAINST DRUG-RESISTANT...vivo OM model. Current studies contrast two CP homeostatic bone-substitute particles, nanometer-sized hydroxyapatite NanOss™ (Nan), and µ-sized

  10. Particle size reduction to the nanometer range: a promising approach to improve buccal absorption of poorly water-soluble drugs

    PubMed Central

    Rao, Shasha; Song, Yunmei; Peddie, Frank; Evans, Allan M

    2011-01-01

    Poorly water-soluble drugs, such as phenylephrine, offer challenging problems for buccal drug delivery. In order to overcome these problems, particle size reduction (to the nanometer range) and cyclodextrin complexation were investigated for permeability enhancement. The apparent solubility in water and the buccal permeation of the original phenylephrine coarse powder, a phenylephrine–cyclodextrin complex and phenylephrine nanosuspensions were characterized. The particle size and particle surface properties of phenylephrine nanosuspensions were used to optimize the size reduction process. The optimized phenylephrine nanosuspension was then freeze dried and incorporated into a multi-layered buccal patch, consisting of a small tablet adhered to a mucoadhesive film, yielding a phenylephrine buccal product with good dosage accuracy and improved mucosal permeability. The design of the buccal patch allows for drug incorporation without the need to change the mucoadhesive component, and is potentially suited to a range of poorly water-soluble compounds. PMID:21753876

  11. Particle size reduction to the nanometer range: a promising approach to improve buccal absorption of poorly water-soluble drugs.

    PubMed

    Rao, Shasha; Song, Yunmei; Peddie, Frank; Evans, Allan M

    2011-01-01

    Poorly water-soluble drugs, such as phenylephrine, offer challenging problems for buccal drug delivery. In order to overcome these problems, particle size reduction (to the nanometer range) and cyclodextrin complexation were investigated for permeability enhancement. The apparent solubility in water and the buccal permeation of the original phenylephrine coarse powder, a phenylephrine-cyclodextrin complex and phenylephrine nanosuspensions were characterized. The particle size and particle surface properties of phenylephrine nanosuspensions were used to optimize the size reduction process. The optimized phenylephrine nanosuspension was then freeze dried and incorporated into a multi-layered buccal patch, consisting of a small tablet adhered to a mucoadhesive film, yielding a phenylephrine buccal product with good dosage accuracy and improved mucosal permeability. The design of the buccal patch allows for drug incorporation without the need to change the mucoadhesive component, and is potentially suited to a range of poorly water-soluble compounds.

  12. A Nanometer Aerosol Size Analyzer (nASA) for Rapid Measurement of High-concentration Size Distributions

    NASA Astrophysics Data System (ADS)

    Han, Hee-Siew; Chen, Da-Ren; Pui, David Y. H.; Anderson, Bruce E.

    2000-03-01

    We have developed a fast-response nanometer aerosol size analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 s. The analyzer includes a bipolar charger (Po210), an extended-length nanometer differential mobility analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 s per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the tandem differential mobility analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T-38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented below.

  13. A Nanometer Aerosol Size Analyzer (nASA) for Rapid Measurement of High-Concentration Size Distributions

    NASA Technical Reports Server (NTRS)

    Han, Hee-Siew; Chen, Da-Ren; Pui, David Y. H.; Anderson, Bruce E.

    2001-01-01

    We have developed a fast-response Nanometer Aerosol Size Analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 seconds. The analyzer includes a bipolar charger (P0210), an extended-length Nanometer Differential Mobility Analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 second per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the Tandem Differential Mobility Analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented.

  14. Size-dependent electrocatalytic activity of gold nanoparticles on HOPG and highly boron-doped diamond surfaces.

    PubMed

    Brülle, Tine; Ju, Wenbo; Niedermayr, Philipp; Denisenko, Andrej; Paschos, Odysseas; Schneider, Oliver; Stimming, Ulrich

    2011-12-06

    Gold nanoparticles were prepared by electrochemical deposition on highly oriented pyrolytic graphite (HOPG) and boron-doped, epitaxial 100-oriented diamond layers. Using a potentiostatic double pulse technique, the average particle size was varied in the range from 5 nm to 30 nm in the case of HOPG as a support and between < 1 nm and 15 nm on diamond surfaces, while keeping the particle density constant. The distribution of particle sizes was very narrow, with standard deviations of around 20% on HOPG and around 30% on diamond. The electrocatalytic activity towards hydrogen evolution and oxygen reduction of these carbon supported gold nanoparticles in dependence of the particle sizes was investigated using cyclic voltammetry. For oxygen reduction the current density normalized to the gold surface (specific current density) increased for decreasing particle size. In contrast, the specific current density of hydrogen evolution showed no dependence on particle size. For both reactions, no effect of the different carbon supports on electrocatalytic activity was observed.

  15. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    DOEpatents

    Gruen, Dieter M.

    2012-09-04

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  16. Self-composite comprised of nanocrystalline diamond and a non-diamond component useful for thermoelectric applications

    DOEpatents

    Gruen, Dieter M [Downers Grove, IL

    2009-08-11

    One provides nanocrystalline diamond material that comprises a plurality of substantially ordered diamond crystallites that are sized no larger than about 10 nanometers. One then disposes a non-diamond component within the nanocrystalline diamond material. By one approach this non-diamond component comprises an electrical conductor that is formed at the grain boundaries that separate the diamond crystallites from one another. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also preserving the thermal conductivity behavior of the nanocrystalline diamond material.

  17. Method to grow carbon thin films consisting entirely of diamond grains 3-5 nm in size and high-energy grain boundaries

    DOEpatents

    Carlisle, John A.; Auciello, Orlando; Birrell, James

    2006-10-31

    An ultrananocrystalline diamond (UNCD) having an average grain size between 3 and 5 nanometers (nm) with not more than about 8% by volume diamond having an average grain size larger than 10 nm. A method of manufacturing UNCD film is also disclosed in which a vapor of acetylene and hydrogen in an inert gas other than He wherein the volume ratio of acetylene to hydrogen is greater than 0.35 and less than 0.85, with the balance being an inert gas, is subjected to a suitable amount of energy to fragment at least some of the acetylene to form a UNCD film having an average grain size of 3 to 5 nm with not more than about 8% by volume diamond having an average grain size larger than 10 nm.

  18. Effect of added dispersants on diamond particles in Ni-diamond composites fabricated with electrodeposition

    NASA Astrophysics Data System (ADS)

    Choi, Yongje; Kim, Donghyun; Son, Kyungsik; Lee, Sanghyuk; Chung, Wonsub

    2015-11-01

    The electrodeposition of Ni-diamond composites was investigated to improve the dispersion and adhesion of the diamond particles, and thus, increase the performance of cutting tools. The additives, so called firstclass brighteners, benzoic sulfimide, benzene sulfonamide, and benzene sulfonic acid were used as dispersants to enhance the dispersivity of diamond particles. The dispersivity was analyzed with Image-Pro software, which was used to asses optical microscopy images, and the number of individual diamond particles and area fraction were calculated. In addition, electrochemical tests were performed, including zeta potential and galvanostatic measurements, and the adhesion strengths was tested by evaluating the wear resistance using ball-on-disk tester. The dispersion and adhesion of the diamond particles were improved when benzoic sulfimide was added to the composite plating bath at a concentration of 0.06 g/L. The number of individual diamond particles was 56 EA/mm2, and the weight loss of alumina ball and specimen was 2.88 mg and 0.80 mg, respectively.

  19. Optical depth localization of nitrogen-vacancy centers in diamond with nanometer accuracy.

    PubMed

    Häußler, Andreas J; Heller, Pascal; McGuinness, Liam P; Naydenov, Boris; Jelezko, Fedor

    2014-12-01

    Precise positioning of nitrogen-vacancy (NV) centers is crucial for their application in sensing and quantum information. Here we present a new purely optical technique enabling determination of the NV position with nanometer resolution. We use a confocal microscope to determine the position of individual emitters along the optical axis. Using two separate detection channels, it is possible to simultaneously measure reflected light from the diamond surface and fluorescent light from the NV center and statistically evaluate both signals. An accuracy of 2.6 nm for shallow NV centers was achieved and is consistent with other techniques for depth determination.

  20. Fabrication of a nanometer thick nitrogen delta doped layer at the sub-surface region of (100) diamond

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Michaelson, Shaul; Saguy, Cecile; Hoffman, Alon

    2016-11-01

    In this letter, we report on the proof of a concept of an innovative delta doping technique to fabricate an ensemble of nitrogen vacancy centers at shallow depths in (100) diamond. A nitrogen delta doped layer with a concentration of ˜1.8 × 1020 cm-3 and a thickness of a few nanometers was produced using this method. Nitrogen delta doping was realized by producing a stable nitrogen terminated (N-terminated) diamond surface using the RF nitridation process and subsequently depositing a thin layer of diamond on the N-terminated diamond surface. The concentration of nitrogen on the N-terminated diamond surface and its stability upon exposure to chemical vapor deposition conditions are determined by x-ray photoelectron spectroscopy analysis. The SIMS profile exhibits a positive concentration gradient of 1.9 nm/decade and a negative gradient of 4.2 nm/decade. The proposed method offers a finer control on the thickness of the delta doped layer than the currently used ion implantation and delta doping techniques.

  1. Significant enhancement of magnetoresistance with the reduction of particle size in nanometer scale

    PubMed Central

    Das, Kalipada; Dasgupta, P.; Poddar, A.; Das, I.

    2016-01-01

    The Physics of materials with large magnetoresistance (MR), defined as the percentage change of electrical resistance with the application of external magnetic field, has been an active field of research for quite some times. In addition to the fundamental interest, large MR has widespread application that includes the field of magnetic field sensor technology. New materials with large MR is interesting. However it is more appealing to vast scientific community if a method describe to achieve many fold enhancement of MR of already known materials. Our study on several manganite samples [La1−xCaxMnO3 (x = 0.52, 0.54, 0.55)] illustrates the method of significant enhancement of MR with the reduction of the particle size in nanometer scale. Our experimentally observed results are explained by considering model consisted of a charge ordered antiferromagnetic core and a shell having short range ferromagnetic correlation between the uncompensated surface spins in nanoscale regime. The ferromagnetic fractions obtained theoretically in the nanoparticles has been shown to be in the good agreement with the experimental results. The method of several orders of magnitude improvement of the magnetoresistive property will have enormous potential for magnetic field sensor technology. PMID:26837285

  2. Effective thermal and mechanical properties of polycrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Cheng, Hao-Yu; Yang, Chi-Yuan; Yang, Li-Chueh; Peng, Kun-Cheng; Chia, Chih-Ta; Liu, Shiu-Jen; Lin, I.-Nan; Lin, Kung-Hsuan

    2018-04-01

    Polycrystalline diamond films were demonstrated as good candidates for electron field emitters, and their mechanical/thermal properties should thus be considered for real devices. We utilized ultrafast optical techniques to investigate the phonon dynamics of several polycrystalline diamond films, prepared by microwave plasma enhanced chemical vapor deposition. The mechanical properties (longitudinal acoustic velocity) and thermal conductivities of diamond films were evaluated from the coherent and incoherent phonon dynamics, respectively. Ultrananocrystalline diamond films were grown using a CH4 (2%)/Ar plasma, while microcrystalline diamond films were grown using a CH4 (2%)/H2 plasma. The ultrananocrystalline diamond film (with a grain size of several nanometers) possesses low acoustic velocity (14.5 nm/ps) and low thermal conductivity (3.17 W/m K) compared with other kinds of diamond films. The acoustic velocity of diamond films increased abruptly to nearly the same as that of natural diamond and remained there when the rod-shaped diamond grains were induced due to the incorporation of H2 in the growth plasma (CH4/Ar). The thermal conductivities of the materials increased monotonously with increasing incorporation of H2 in the growth plasma (CH4/Ar). The thermal conductivity of 25.6 W/m K was attained for nanocrystalline diamond films containing spherical diamond grains (with a size of several tens of nanometers). Compared with single crystalline diamond, the low thermal conductivity of polycrystalline films results from phonon scattering at the interfaces of grains and amorphous carbon in the boundary phases.

  3. On the validity of the Poisson assumption in sampling nanometer-sized aerosols

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

    Damit, Brian E; Wu, Dr. Chang-Yu; Cheng, Mengdawn

    2014-01-01

    A Poisson process is traditionally believed to apply to the sampling of aerosols. For a constant aerosol concentration, it is assumed that a Poisson process describes the fluctuation in the measured concentration because aerosols are stochastically distributed in space. Recent studies, however, have shown that sampling of micrometer-sized aerosols has non-Poissonian behavior with positive correlations. The validity of the Poisson assumption for nanometer-sized aerosols has not been examined and thus was tested in this study. Its validity was tested for four particle sizes - 10 nm, 25 nm, 50 nm and 100 nm - by sampling from indoor air withmore » a DMA- CPC setup to obtain a time series of particle counts. Five metrics were calculated from the data: pair-correlation function (PCF), time-averaged PCF, coefficient of variation, probability of measuring a concentration at least 25% greater than average, and posterior distributions from Bayesian inference. To identify departures from Poissonian behavior, these metrics were also calculated for 1,000 computer-generated Poisson time series with the same mean as the experimental data. For nearly all comparisons, the experimental data fell within the range of 80% of the Poisson-simulation values. Essentially, the metrics for the experimental data were indistinguishable from a simulated Poisson process. The greater influence of Brownian motion for nanometer-sized aerosols may explain the Poissonian behavior observed for smaller aerosols. Although the Poisson assumption was found to be valid in this study, it must be carefully applied as the results here do not definitively prove applicability in all sampling situations.« less

  4. Pulsed Electrodeposition of Ni with Uniform Co-Deposition of Micron Sized Diamond Particles on Copper Substrate

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Mahato, Neelima

    Nanocrystalline nickel was deposited on annealed copper substrate of unit surface area (1 cm2) via pulsed electrodeposition technique using potentiostat (model 263A, Princeton Applied Research, USA) from Watts bath containing nickel sulfate, nickel chloride ,boric acid and sodium citrate. Diamond particles of three different dimensions, viz., 1, 3, and 6 micron were added separately (5 g/L) to the watts bath and co-deposited along with nanocrystalline nickel. The temperature was kept constant at 55 °C. The solution was ultrasonicated for 45-60 minutes prior to deposition to disperse the diamond particles uniformly in the bath. Depositions were carried out at different current densities, viz., 50, 100,150 and 200 mA/ cm2 for different durations, i.e.7, 14 and 21 minutes and best results are optimized for 200mA/cm2 so it is used for all process here .Scanning electron micrographs (SEM) show uniform deposition of microstructure of micron diamond on the surface of copper embedded in the nickel matrix. Elemental mapping confirmed uniform deposition of nickel and diamond with almost no cracks or pits. Mechanical properties of the sample such as, Vicker's hardness increased abruptly after the electrodeposition. Improved microstructural and mechanical properties were found in the case of electrodeposited surfaces containing followed by 3 and 6 micron diamond. The properties were also found better than those processed via stirring the solution during deposition.

  5. Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

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

    Kang, Qiping; He, Xinbo, E-mail: xb_he@163.com; Ren, Shubin

    2015-07-15

    An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO{sub 3} in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658 W m{sup −} {sup 1}more » K{sup −} {sup 1}. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained. - Highlights: • WC coating was successfully synthesized on diamond particles in molten salts. • WC coating obviously promoted the wettability of diamond and copper matrix. • WC coating greatly enhanced the thermal conductivity of Cu–diamond composite. • The composites are suitable candidates for heat sink applications.« less

  6. Radiation-induced diamond crystallization: Origin of carbonados and its implications on meteorite nano-diamonds

    USGS Publications Warehouse

    Ozima, M.; Tatsumoto, M.

    1997-01-01

    Ten carbonados from Central Africa were studied for U-Th-Pb systematics. To extract U, Th, and Pb from the samples, we developed a cold combustion technique wherein diamond was burnt in liquid oxygen. The technique gave low blanks; 25-50 pg for Pb, 3 pg for U, and 5 pg for Th. After very thorough acid treatments of the carbonados with hot HNO3, HF, and HCl over one week, most of U, Th, and Pb were removed from the samples. Lead in the acid-leached diamonds was highly radiogenic (206Pb/204Pb up to 470). However, the amounts of U and Th in the acid-leached diamonds are too low to account for the radiogenic Pb even if we assume 4.5 Ga for the age of the diamonds. Therefore, we conclude that the radiogenic Pb was implanted into the diamonds from surroundings by means of recoil energy of radioactive decays of U and Th. From the radiogenic lead isotopic composition, we estimate a minimum age of 2.6 Ga and a maximum age of 3.8 Ga for the formation of the carbonados. The above findings of the implantation of recoiled radiogenic Pb into carbonados is consistent with the process of radiation-induced crystallization which was proposed for carbonado by Kaminsky (1987). We show from some theoretical considerations that when highly energetic particles, such as those emitted from radioactive decay of U and Th, interact with carbonaceous materials, they give rise to cascades of atomic disturbance (over regions of about a few nanometer), and the disturbed atoms are likely to recrystallize to form micro-diamonds because of increasing surface energy due to small size. The radiation-induced diamond formation mechanism may be relevant to the origin of nano-diamonds in primitive meteorites. Copyright ?? 1997 Elsevier Science Ltd.

  7. Controllable surface-plasmon resonance in engineered nanometer epitaxial silicide particles embedded in silicon

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; Ksendzov, A.; Iannelli, J. M.; George, T.

    1991-01-01

    Epitaxial CoSi2 particles in a single-crystal silicon matrix are grown by molecular-beam epitaxy using a technique that allows nanometer control over particle size in three dimensions. These composite layers exhibit resonant absorption predicted by effective-medium theory. Selection of the height and diameter of disklike particles through a choice of growth conditions allows tailoring of the depolarization factor and hence of the surface-plasmon resonance energy. Resonant absorption from 0.49 to 1.04 eV (2.5 to 1.2 micron) is demonstrated and shown to agree well with values predicted by the Garnett (1904, 1906) theory using the bulk dielectric constants for CoSi2 and Si.

  8. Cooling the center-of-mass motion of a diamond nanocrystal in a magneto-gravitational trap

    NASA Astrophysics Data System (ADS)

    Hsu, Jen-Feng

    A magneto-gravitational trap for micro/nanometer sized diamagnetic particles, such as diamond nanocrystals, is tested and characterized. After exploring various other systems, such as a suspended graphene beam and an optical trap, this magneto-gravitational nanomechanical trapping system for diamond with nitrogen-vacancy (NV) centers presents unique advantages for experiments in fundamental quantum mechanics. Those include, for example, the generation of large quantum superposition states and tests of quantum gravity. Features are demonstrated for this system, such as stable and passive levitation from atmospheric pressure to high vacuum, low resonant frequencies and damping rates, and cooling of the center-of-mass motions to below 1 K. The construction of the trap, vacuum system, optics, and motion detection electronics are described in detail.

  9. Direct observation and analysis of york-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

    NASA Astrophysics Data System (ADS)

    Asahina, Shunsuke; Suga, Mitsuo; Takahashi, Hideyuki; Young Jeong, Hu; Galeano, Carolina; Schüth, Ferdi; Terasaki, Osamu

    2014-11-01

    Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in yolk-shell materials of Au@C, Ru/Pt@C, Au@TiO2, and Pt@Polymer. Progresses in the following categories were shown for the yolk-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

  10. Study on the Effect of Diamond Grain Size on Wear of Polycrystalline Diamond Compact Cutter

    NASA Astrophysics Data System (ADS)

    Abdul-Rani, A. M.; Che Sidid, Adib Akmal Bin; Adzis, Azri Hamim Ab

    2018-03-01

    Drilling operation is one of the most crucial step in oil and gas industry as it proves the availability of oil and gas under the ground. Polycrystalline Diamond Compact (PDC) bit is a type of bit which is gaining popularity due to its high Rate of Penetration (ROP). However, PDC bit can easily wear off especially when drilling hard rock. The purpose of this study is to identify the relationship between the grain sizes of the diamond and wear rate of the PDC cutter using simulation-based study with FEA software (ABAQUS). The wear rates of a PDC cutter with a different diamond grain sizes were calculated from simulated cuttings of cutters against granite. The result of this study shows that the smaller the diamond grain size, the higher the wear resistivity of PDC cutter.

  11. Interaction of micron and nano-sized particles with cells of the dura mater.

    PubMed

    Papageorgiou, Iraklis; Marsh, Rainy; Tipper, Joanne L; Hall, Richard M; Fisher, John; Ingham, Eileen

    2014-10-01

    Intervertebral total disc replacements (TDR) are used in the treatment of degenerative spinal disc disease. There are, however, concerns that they may be subject to long-term failure due to wear. The adverse effects of TDR wear have the potential to manifest in the dura mater and surrounding tissues. The aim of this study was to investigate the physiological structure of the dura mater, isolate the resident dural epithelial and stromal cells and analyse the capacity of these cells to internalise model polymer particles. The porcine dura mater was a collagen-rich structure encompassing regularly arranged fibroblastic cells within an outermost epithelial cell layer. The isolated dural epithelial cells had endothelial cell characteristics (positive for von Willebrand factor, CD31, E-cadherin and desmoplakin) and barrier functionality whereas the fibroblastic cells were positive for collagen I and III, tenascin and actin. The capacity of the dural cells to take up model particles was dependent on particle size. Nanometer sized particles readily penetrated both types of cells. However, dural fibroblasts engulfed micron-sized particles at a much higher rate than dural epithelial cells. The study suggested that dural epithelial cells may offer some barrier to the penetration of micron-sized particles but not nanometer sized particles. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

  12. Inherent size effects on XANES of nanometer metal clusters: Size-selected platinum clusters on silica

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

    Dai, Yang; Gorey, Timothy J.; Anderson, Scott L.

    2016-12-12

    X-ray absorption near-edge structure (XANES) is commonly used to probe the oxidation state of metal-containing nanomaterials, however, as the particle size in the material drops below a few nanometers, it becomes important to consider inherent size effects on the electronic structure of the materials. In this paper, we analyze a series of size-selected Pt n/SiO 2 samples, using X-ray photoelectron spectroscopy (XPS), low energy ion scattering, grazing-incidence small angle X-ray scattering, and XANES. The oxidation state and morphology are characterized both as-deposited in UHV, and after air/O 2 exposure and annealing in H 2. Here, the clusters are found tomore » be stable during deposition and upon air exposure, but sinter if heated above ~150 °C. XANES shows shifts in the Pt L 3 edge, relative to bulk Pt, that increase with decreasing cluster size, and the cluster samples show high white line intensity. Reference to bulk standards would suggest that the clusters are oxidized, however, XPS shows that they are not. Instead, the XANES effects are attributable to development of a band gap and localization of empty state wavefunctions in small clusters.« less

  13. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles

    PubMed Central

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-01-01

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air. PMID:26831205

  14. Enhancement of oxidation resistance via a self-healing boron carbide coating on diamond particles.

    PubMed

    Sun, Youhong; Meng, Qingnan; Qian, Ming; Liu, Baochang; Gao, Ke; Ma, Yinlong; Wen, Mao; Zheng, Weitao

    2016-02-02

    A boron carbide coating was applied to diamond particles by heating the particles in a powder mixture consisting of H3BO3, B and Mg. The composition, bond state and coverage fraction of the boron carbide coating on the diamond particles were investigated. The boron carbide coating prefers to grow on the diamond (100) surface than on the diamond (111) surface. A stoichiometric B4C coating completely covered the diamond particle after maintaining the raw mixture at 1200 °C for 2 h. The contribution of the boron carbide coating to the oxidation resistance enhancement of the diamond particles was investigated. During annealing of the coated diamond in air, the priory formed B2O3, which exhibits a self-healing property, as an oxygen barrier layer, which protected the diamond from oxidation. The formation temperature of B2O3 is dependent on the amorphous boron carbide content. The coating on the diamond provided effective protection of the diamond against oxidation by heating in air at 1000 °C for 1 h. Furthermore, the presence of the boron carbide coating also contributed to the maintenance of the static compressive strength during the annealing of diamond in air.

  15. Subnanometer and nanometer catalysts, method for preparing size-selected catalysts

    DOEpatents

    Vajda, Stefan , Pellin, Michael J.; Elam, Jeffrey W [Elmhurst, IL; Marshall, Christopher L [Naperville, IL; Winans, Randall A [Downers Grove, IL; Meiwes-Broer, Karl-Heinz [Roggentin, GR

    2012-04-03

    Highly uniform cluster based nanocatalysts supported on technologically relevant supports were synthesized for reactions of top industrial relevance. The Pt-cluster based catalysts outperformed the very best reported ODHP catalyst in both activity (by up to two orders of magnitude higher turn-over frequencies) and in selectivity. The results clearly demonstrate that highly dispersed ultra-small Pt clusters precisely localized on high-surface area supports can lead to affordable new catalysts for highly efficient and economic propene production, including considerably simplified separation of the final product. The combined GISAXS-mass spectrometry provides an excellent tool to monitor the evolution of size and shape of nanocatalyst at action under realistic conditions. Also provided are sub-nanometer gold and sub-nanometer to few nm size-selected silver catalysts which possess size dependent tunable catalytic properties in the epoxidation of alkenes. Invented size-selected cluster deposition provides a unique tool to tune material properties by atom-by-atom fashion, which can be stabilized by protective overcoats.

  16. Subnanometer and nanometer catalysts, method for preparing size-selected catalysts

    DOEpatents

    Vajda, Stefan [Lisle, IL; Pellin, Michael J [Naperville, IL; Elam, Jeffrey W [Elmhurst, IL; Marshall, Christopher L [Naperville, IL; Winans, Randall A [Downers Grove, IL; Meiwes-Broer, Karl-Heinz [Roggentin, GR

    2012-03-27

    Highly uniform cluster based nanocatalysts supported on technologically relevant supports were synthesized for reactions of top industrial relevance. The Pt-cluster based catalysts outperformed the very best reported ODHP catalyst in both activity (by up to two orders of magnitude higher turn-over frequencies) and in selectivity. The results clearly demonstrate that highly dispersed ultra-small Pt clusters precisely localized on high-surface area supports can lead to affordable new catalysts for highly efficient and economic propene production, including considerably simplified separation of the final product. The combined GISAXS-mass spectrometry provides an excellent tool to monitor the evolution of size and shape of nanocatalyst at action under realistic conditions. Also provided are sub-nanometer gold and sub-nanometer to few nm size-selected silver catalysts which possess size dependent tunable catalytic properties in the epoxidation of alkenes. Invented size-selected cluster deposition provides a unique tool to tune material properties by atom-by-atom fashion, which can be stabilized by protective overcoats.

  17. Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces.

    PubMed

    Yoshikawa, Taro; Zuerbig, Verena; Gao, Fang; Hoffmann, René; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

    2015-05-19

    Monosized (∼4 nm) diamond nanoparticles arranged on substrate surfaces are exciting candidates for single-photon sources and nucleation sites for ultrathin nanocrystalline diamond film growth. The most commonly used technique to obtain substrate-supported diamond nanoparticles is electrostatic self-assembly seeding using nanodiamond colloidal suspensions. Currently, monodisperse nanodiamond colloids, which have a narrow distribution of particle sizes centering on the core particle size (∼4 nm), are available for the seeding technique on different substrate materials such as Si, SiO2, Cu, and AlN. However, the self-assembled nanoparticles tend to form small (typically a few tens of nanometers or even larger) aggregates on all of those substrate materials. In this study, this major weakness of self-assembled diamond nanoparticles was solved by modifying the salt concentration of nanodiamond colloidal suspensions. Several salt concentrations of colloidal suspensions were prepared using potassium chloride as an inserted electrolyte and were examined with respect to seeding on SiO2 surfaces. The colloidal suspensions and the seeded surfaces were characterized by dynamic light scattering and atomic force microscopy, respectively. Also, the interaction energies between diamond nanoparticles in each of the examined colloidal suspensions were compared on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. From these investigations, it became clear that the appropriate salt concentration suppresses the formation of small aggregates during the seeding process owing to the modified electrostatic repulsive interaction between nanoparticles. Finally, monosized (<10 nm) individual diamond nanoparticles arranged on SiO2 surfaces have been successfully obtained.

  18. Status of diamond particle detectors

    NASA Astrophysics Data System (ADS)

    Krammer, M.; Adam, W.; Bauer, C.; Berdermann, E.; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fish, D.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Knöpfle, K. T.; Manfredi, P. F.; Meier, D.; Mishina, M.; LeNormand, F.; Pan, L. S.; Pernegger, H.; Pernicka, M.; Re, V.; Riester, G. L.; Roe, S.; Roff, D.; Rudge, A.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Turchetta, R.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Ziock, H.; Zoeller, M.

    1998-11-01

    To continue the exciting research in the field of particle physics new accelerators and experiments are under construction. In some of these experiments, e.g. ATLAS and CMS at the Large Hadron Collider at CERN or HERA-B at DESY, the detectors have to withstand an extreme environment. The detectors must be radiation hard, provide a very fast signal, and be as thin as possible. The properties of CVD diamond allow to fulfill these requirements and make it an ideal material for the detectors close to the interaction region of these experiments, i.e. the vertex detectors or the inner trackers. The RD42 collaboration is developing diamond detectors for these applications. The program of RD42 includes the improvement of the charge collection properties of CVD diamond, the study of the radiation hardness and the development of low-noise radiation hard readout electronics. An overview of the progress achieved during the last years will be given.

  19. Grain-size-dependent diamond-nondiamond composite films: characterization and field-emission properties.

    PubMed

    Pradhan, Debabrata; Lin, I Nan

    2009-07-01

    Diamond films with grain sizes in the range of 5-1000 nm and grain boundaries containing nondiamond carbon are deposited on a silicon substrate by varying the deposition parameters. The overall morphologies of the as-deposited diamond-nondiamond composite films are examined by scanning electron microscopy and atomic force microscopy, which show a decrease in the surface roughness with a decrease in the diamond grain size. Although the Raman spectra show predominately nondiamond carbon features in the diamond films with smaller grain sizes, glancing-angle X-ray diffraction spectra show the absence of graphitic carbon features and the presence of very small amorphous carbon diffraction features. The CH4 percentage (%) in Ar and H2 plasma during deposition plays a crucial role in the formation of diamond films with different grain sizes and nondiamond carbon contents, which, in turn, determines the field-emission behavior of the corresponding diamond films. The smaller the grain size of the diamond, the lower is the turn-on field for electron emission. A lower turn-on field is obtained from the diamond films deposited with 2-5% CH4 than from the films deposited with either 1% or 7.5% CH4 in the Ar medium. A current density greater than 1 mA/cm2 (at 50 V/microm) is obtained from diamond films deposited with a higher percentage of CH4. A model is suggested for the field-emission mechanism from the diamond-nondiamond composite films with different diamond grain sizes and nondiamond contents.

  20. Interaction of micron and nano-sized particles with cells of the dura mater

    PubMed Central

    Papageorgiou, Iraklis; Marsh, Rainy; Tipper, Joanne L; Hall, Richard M; Fisher, John; Ingham, Eileen

    2014-01-01

    Intervertebral total disc replacements (TDR) are used in the treatment of degenerative spinal disc disease. There are, however, concerns that they may be subject to long-term failure due to wear. The adverse effects of TDR wear have the potential to manifest in the dura mater and surrounding tissues. The aim of this study was to investigate the physiological structure of the dura mater, isolate the resident dural epithelial and stromal cells and analyse the capacity of these cells to internalise model polymer particles. The porcine dura mater was a collagen-rich structure encompassing regularly arranged fibroblastic cells within an outermost epithelial cell layer. The isolated dural epithelial cells had endothelial cell characteristics (positive for von Willebrand factor, CD31, E-cadherin and desmoplakin) and barrier functionality whereas the fibroblastic cells were positive for collagen I and III, tenascin and actin. The capacity of the dural cells to take up model particles was dependent on particle size. Nanometer sized particles readily penetrated both types of cells. However, dural fibroblasts engulfed micron-sized particles at a much higher rate than dural epithelial cells. The study suggested that dural epithelial cells may offer some barrier to the penetration of micron-sized particles but not nanometer sized particles. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1496–1505, 2014. PMID:24604838

  1. A theoretical consideration of ion size effects on the electric double layer and voltammetry of nanometer-sized disk electrodes.

    PubMed

    Gao, Yu; Liu, Yuwen; Chen, Shengli

    2016-12-12

    Considering that an electric-double-layer (EDL) structure may significantly impact on the mass transport and charge transfer kinetics at the interfaces of nanometer-sized electrodes, while EDL structures could be altered by the finite sizes of electrolyte and redox ions, the possible effects of ion sizes on EDL structures and voltammetric responses of nanometer-sized disk (nanodisk) electrodes are investigated. Modified Boltzmann and Nernst-Planck (NP) equations, which include the influence of the finite ion volumes, are combined with the Poisson equation and modified Butler-Volmer equation to gain knowledge on how the finite sizes of ions and the nanometer sizes of electrodes may couple with each other to affect the structures and reactivities of a nanoscale electrochemical interface. Two typical ion radii, 0.38 nm and 0.68 nm, which could represent the sizes of the commonly used aqueous electrolyte ions (e.g., the solvated K + ) and the organic electrolyte ions (e.g., the solvated TEA + ) respectively, are considered. The finite size of ions can result in decreased screening of electrode charges, therefore magnifying EDL effects on the ion transport and the electron transfer at electrochemical interfaces. This finite size effect of ions becomes more pronounced for larger ions and at smaller electrodes as the electrode radii is larger than 10 nm. For electrodes with radii smaller than 10 nm, however, the ion size effect may be less pronounced with decreasing the electrode size. This can be explained in terms of the increased edge effect of disk electrodes at nanometer scales, which could relax the ion crowding at/near the outer Helmholtz plane. The conditions and situations under which the ion sizes may have a significant effect on the voltammetry of electrodes are discussed.

  2. Extraterrestrial diamond inclusions reveal a Mars-sized planet

    NASA Astrophysics Data System (ADS)

    Nabiei, F.; Badro, J.; Dennenwaldt, T.; Oveisi, E.; Cantoni, M.; Hébert, C.; El Goresy, A.; Barrat, J. A.; Gillet, P.

    2017-12-01

    Ureilites are achondritic meteorites, distinct by their high carbon content. Carbon dominantly exists as graphite and diamond forming veins between olivine and pyroxene grains in the matrix. The presence of diamonds is, often, attributed to the shock-induced transformation from graphite. However, a recent study (Miyahara et al. 2016) on Almahata Sitta MS-170 mainly based on the large size of diamonds suggested their growth in the static high pressure conditions of planetary interior. We prepared five thin sections by the focused ion beam (FIB) from the diamonds in Almahatta Sitta MS-170 for transmission electron microscopy (TEM) analysis. Abundance of dislocations, stacking faults and {111} twinnings indicate significant deformation. Moreover, large numbers of inclusions are found in diamonds. Electron energy-loss spectroscopy (EELS) showed that when a twinning is intersected with an inclusion, it transforms to graphite. This together with other morphological and crystallographical characteristics of the graphite and diamond phases point to the shock-induced transformation of diamond to graphite. Energy dispersive X-ray (EDX) spectroscopy and electron diffraction were used to chemically and structurally characterize the diamond inclusions. Most of the inclusions are Fe-Ni-S-P type up to 60 nm in diameter, each consisting of three phases: kamacite (Fe, Ni), troilite (FeS) and Schreibersite ((Fe,Ni)3P). The inclusions always have euhedral shape indicating the existence of a parent phase that later broke down. Chemical analysis of complete inclusions (identified with electron tomography) agrees with the stoichiometric (Fe0.93,Ni0.07)3(S0.88,P0.12) phase that only forms above 21 GPa (Gu et al. 2016). The ureilite parent body (UPB) needs to be at least about Mars-sized to generate such a pressure at its core-mantle boundary. This is in the same size range estimated for the planetary embryos forming early in the Solar System. Moreover, although the UPB did not go through

  3. Critical current densities of powder-in-tube MgB2 tapes fabricated with nanometer-size Mg powder

    NASA Astrophysics Data System (ADS)

    Yamada, H.; Hirakawa, M.; Kumakura, H.; Matsumoto, A.; Kitaguchi, H.

    2004-03-01

    We fabricated powder-in-tube MgB2/Fe tapes using a powder mixture of nanometer-size Mg and commercial amorphous B and investigated the transport properties. High-purity nanometer-size Mg powder was fabricated by applying the thermal plasma method. 5-10 mol % SiC powder doping was tried to enhance the Jc properties. We found that the use of nanometer-size Mg powder was effective to increase the Jc values. The transport Jc values of the nondoped and 10 mol % SiC-doped tapes prepared with nanometer-size Mg powder reached 90 and 250 A/mm2 at 4.2 K and 10 T, respectively. These values were about five times higher than those of the tapes prepared with commercial Mg powder.

  4. Diamond cubic phase of monoolein and water as an amphiphilic matrix for electrophoresis of oligonucleotides.

    PubMed

    Carlsson, Nils; Winge, Ann-Sofie; Engström, Sven; Akerman, Björn

    2005-10-06

    We used a cubic liquid crystal formed by the nonionic monoglyceride monoolein and water as a porous matrix for the electrophoresis of oligonucleotides. The diamond cubic phase is thermodynamically stable when in contact with a water-rich phase, which we exploit to run the electrophoresis in the useful submarine mode. Oligonucleotides are separated according to size and secondary structure by migration through the space-filling aqueous nanometer pores of the regular liquid crystal, but the comparatively slow migration means the cubic phase will not be a replacement for the conventional DNA gels. However, our demonstration that the cubic phase can be used in submarine electrophoresis opens up the possibility for a new matrix for electrophoresis of amphiphilic molecules. From this perspective, the results on the oligonucleotides show that water-soluble particles of nanometer size, typical for the hydrophilic parts of membrane-bound proteins, may be a useful separation motif. A charged contamination in the commercial sample of monoolein, most likely oleic acid that arises from its hydrolysis, restricts useful buffer conditions to a pH below 5.6.

  5. Properties of Diamond and Diamond-Like Clusters in Nanometric Dimensions

    NASA Technical Reports Server (NTRS)

    Halicioglu, Timur; Langhoff, Stephen R. (Technical Monitor)

    1996-01-01

    Variations in materials properties of small clusters of nanometric dimensions were investigated. Investigations were carried out for diamond and diamond-like particles in spherical shapes. Calculations were performed for clusters containing over 1000 carbon atoms. Results indicate that as the cluster size diminishes, (i) the average cohesive energy becomes weaker, (ii) the excess surface energy increases, and (iii) the value for stiffness decreases.

  6. Highly crystallized nanometer-sized zeolite a with large Cs adsorption capability for the decontamination of water.

    PubMed

    Torad, Nagy L; Naito, Masanobu; Tatami, Junichi; Endo, Akira; Leo, Sin-Yen; Ishihara, Shinsuke; Wu, Kevin C-W; Wakihara, Toru; Yamauchi, Yusuke

    2014-03-01

    Nanometer-sized zeolite A with a large cesium (Cs) uptake capability is prepared through a simple post-milling recrystallization method. This method is suitable for producing nanometer-sized zeolite in large scale, as additional organic compounds are not needed to control zeolite nucleation and crystal growth. Herein, we perform a quartz crystal microbalance (QCM) study to evaluate the uptake ability of Cs ions by zeolite, to the best of our knowledge, for the first time. In comparison to micrometer-sized zeolite A, nanometer-sized zeolite A can rapidly accommodate a larger amount of Cs ions into the zeolite crystal structure, owing to its high external surface area. Nanometer-sized zeolite is a promising candidate for the removal of radioactive Cs ions from polluted water. Our QCM study on Cs adsorption uptake behavior provides the information of adsorption kinetics (e.g., adsorption amounts and rates). This technique is applicable to other zeolites, which will be highly valuable for further consideration of radioactive Cs removal in the future. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Continuous scanning of the mobility and size distribution of charged clusters and nanometer particles in atmospheric air and the Balanced Scanning Mobility Analyzer BSMA

    NASA Astrophysics Data System (ADS)

    Tammet, H.

    2006-12-01

    Measuring of charged nanometer particles in atmospheric air is a routine task in research on atmospheric electricity, where these particles are called the atmospheric ions. An aspiration condenser is the most popular instrument for measuring atmospheric ions. Continuous scanning of a mobility distribution is possible when the aspiration condenser is connected as an arm of a balanced bridge. Transfer function of an aspiration condenser is calculated according to the measurements of geometric dimensions, air flow rate, driving voltage, and electric current. The most complicated phase of the calibration is the estimation of the inlet loss of ions due to the Brownian deposition. The available models of ion deposition on the protective inlet screen and the inlet control electrofilter have the uncertainty of about 20%. To keep the uncertainty of measurements low the adsorption should not exceed a few tens of percent. The online conversion of the mobility distribution to the size distribution and a correct reduction of inlet losses are possible when air temperature and pressure are measured simultaneously with the mobility distribution. Two instruments called the Balanced Scanning Mobility Analyzers (BSMA) were manufactured and tested in routine atmospheric measurements. The concentration of atmospheric ions of the size of about a few nanometers is very low and a high air flow rate is required to collect enough of ion current. The air flow of 52 l/s exceeds the air flow in usual aerosol instruments by 2-3 orders of magnitude. The high flow rate reduces the time of ion passage to 60 ms and the heating of air in an analyzer to 0.2 K, which suppresses a possible transformation of ions inside the instrument. The mobility range of the BSMA of 0.032-3.2 cm 2 V - 1 s - 1 is logarithmically uniformly divided into 16 fractions. The size distribution is presented by 12 fractions in the diameter range of 0.4-7.5 nm. The measurement noise of a fraction concentration is typically

  8. Biofunctionalization of scaffold material with nano-scaled diamond particles physisorbed with angiogenic factors enhances vessel growth after implantation.

    PubMed

    Schimke, Magdalena M; Stigler, Robert; Wu, Xujun; Waag, Thilo; Buschmann, Peter; Kern, Johann; Untergasser, Gerold; Rasse, Michael; Steinmüller-Nethl, Doris; Krueger, Anke; Lepperdinger, Günter

    2016-04-01

    Biofunctionalized scaffold facilitates complete healing of large defects. Biological constraints are induction and ingrowth of vessels. Angiogenic growth factors such as vascular endothelial growth factor or angiopoietin-1 can be bound to nano-scaled diamond particles. Corresponding bioactivities need to be examined after biofunctionalization. We therefore determined the physisorptive capacity of distinctly manufactured, differently sized nDP and the corresponding activities of bound factors. The properties of biofunctionalized nDPs were investigated on cultivated human mesenchymal stem cells and on the developing chicken embryo chorio-allantoic membrane. Eventually porous bone substitution material was coated with nDP to generate an interface that allows biofactor physisorption. Angiopoietin-1 was applied shortly before scaffold implantation into an osseous defect in sheep calvaria. Biofunctionalized scaffolds exhibited significantly increased rates of angiogenesis already one month after implantation. Conclusively, nDP can be used to ease functionalization of synthetic biomaterials. With the advances in nanotechnology, many nano-sized materials have been used in the biomedical field. This is also true for nano-diamond particles (nDP). In this article, the authors investigated the physical properties of functionalized nano-diamond particles in both in-vitro and in-vivo settings. The positive findings would help improve understanding of these nanomaterials in regenerative medicine. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. The impact of diamond nanocrystallinity on osteoblast functions.

    PubMed

    Yang, Lei; Sheldon, Brian W; Webster, Thomas J

    2009-07-01

    Nanocrystalline diamond has been proposed as an anti-abrasive film on orthopedic implants. In this study, osteoblast (bone forming cells) functions including adhesion (up to 4h), proliferation (up to 5 days) and differentiation (up to 21 days) on different diamond film topographies were systematically investigated. In order to exclude interferences from changes in surface chemistry and wettability (energy), diamond films with nanometer and micron scale topographies were fabricated through microwave plasma enhanced chemical-vapor-deposition and hydrogen plasma treatment. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and water contact angle measurements verified the similar surface chemistry and wettability but varied topographies for all of the diamond films prepared on silicon in this study. Cytocompatibility assays demonstrated enhanced osteoblast functions (including adhesion, proliferation, intracellular protein synthesis, alkaline phosphatase activity and extracellular calcium deposition) on nanocrystalline diamond compared to submicron diamond grain size films for all time periods tested up to 21 days. An SEM study of osteoblast attachment helped to explain the topographical impact diamond had on osteoblast functions by showing altered filopodia extensions on the different diamond topographies. In summary, these results provided insights into understanding the role diamond nanotopography had on osteoblast interactions and more importantly, the application of diamond films to improve orthopedic implant lifetimes.

  10. Diamond detectors for high energy physics experiments

    NASA Astrophysics Data System (ADS)

    Bäni, L.; Alexopoulos, A.; Artuso, M.; Bachmair, F.; Bartosik, M.; Beacham, J.; Beck, H.; Bellini, V.; Belyaev, V.; Bentele, B.; Berdermann, E.; Bergonzo, P.; Bes, A.; Brom, J.-M.; Bruzzi, M.; Cerv, M.; Chiodini, G.; Chren, D.; Cindro, V.; Claus, G.; Collot, J.; Cumalat, J.; Dabrowski, A.; D'Alessandro, R.; Dauvergne, D.; de Boer, W.; Dorfer, C.; Dünser, M.; Eremin, V.; Eusebi, R.; Forcolin, G.; Forneris, J.; Frais-Kölbl, H.; Gallin-Martel, L.; Gallin-Martel, M. L.; Gan, K. K.; Gastal, M.; Giroletti, C.; Goffe, M.; Goldstein, J.; Golubev, A.; Gorišek, A.; Grigoriev, E.; Grosse-Knetter, J.; Grummer, A.; Gui, B.; Guthoff, M.; Haughton, I.; Hiti, B.; Hits, D.; Hoeferkamp, M.; Hofmann, T.; Hosslet, J.; Hostachy, J.-Y.; Hügging, F.; Hutton, C.; Jansen, H.; Janssen, J.; Kagan, H.; Kanxheri, K.; Kasieczka, G.; Kass, R.; Kassel, F.; Kis, M.; Konovalov, V.; Kramberger, G.; Kuleshov, S.; Lacoste, A.; Lagomarsino, S.; Lo Giudice, A.; Lukosi, E.; Maazouzi, C.; Mandic, I.; Mathieu, C.; Menichelli, M.; Mikuž, M.; Morozzi, A.; Moss, J.; Mountain, R.; Murphy, S.; Muškinja, M.; Oh, A.; Oliviero, P.; Passeri, D.; Pernegger, H.; Perrino, R.; Picollo, F.; Pomorski, M.; Potenza, R.; Quadt, A.; Re, A.; Reichmann, M.; Riley, G.; Roe, S.; Sanz, D.; Scaringella, M.; Schaefer, D.; Schmidt, C. J.; Schnetzer, S.; Sciortino, S.; Scorzoni, A.; Seidel, S.; Servoli, L.; Smith, S.; Sopko, B.; Sopko, V.; Spagnolo, S.; Spanier, S.; Stenson, K.; Stone, R.; Sutera, C.; Tannenwald, B.; Taylor, A.; Traeger, M.; Tromson, D.; Trischuk, W.; Tuve, C.; Uplegger, L.; Velthuis, J.; Venturi, N.; Vittone, E.; Wagner, S.; Wallny, R.; Wang, J. C.; Weingarten, J.; Weiss, C.; Wengler, T.; Wermes, N.; Yamouni, M.; Zavrtanik, M.

    2018-01-01

    Beam test results of the radiation tolerance study of chemical vapour deposition (CVD) diamond against different particle species and energies is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition functionality of poly-crystalline CVD diamond 3D devices was demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high luminosity experiments.

  11. Polycrystalline CVD diamond device level modeling for particle detection applications

    NASA Astrophysics Data System (ADS)

    Morozzi, A.; Passeri, D.; Kanxheri, K.; Servoli, L.; Lagomarsino, S.; Sciortino, S.

    2016-12-01

    Diamond is a promising material whose excellent physical properties foster its use for radiation detection applications, in particular in those hostile operating environments where the silicon-based detectors behavior is limited due to the high radiation fluence. Within this framework, the application of Technology Computer Aided Design (TCAD) simulation tools is highly envisaged for the study, the optimization and the predictive analysis of sensing devices. Since the novelty of using diamond in electronics, this material is not included in the library of commercial, state-of-the-art TCAD software tools. In this work, we propose the development, the application and the validation of numerical models to simulate the electrical behavior of polycrystalline (pc)CVD diamond conceived for diamond sensors for particle detection. The model focuses on the characterization of a physically-based pcCVD diamond bandgap taking into account deep-level defects acting as recombination centers and/or trap states. While a definite picture of the polycrystalline diamond band-gap is still debated, the effect of the main parameters (e.g. trap densities, capture cross-sections, etc.) can be deeply investigated thanks to the simulated approach. The charge collection efficiency due to β -particle irradiation of diamond materials provided by different vendors and with different electrode configurations has been selected as figure of merit for the model validation. The good agreement between measurements and simulation findings, keeping the traps density as the only one fitting parameter, assesses the suitability of the TCAD modeling approach as a predictive tool for the design and the optimization of diamond-based radiation detectors.

  12. Fabrication of Controllable Pore and Particle Size of Mesoporous Silica Nanoparticles via a Liquid-phase Synthesis Method and Its Absorption Characteristics

    NASA Astrophysics Data System (ADS)

    Nandiyanto, Asep Bayu Dani; Iskandar, Ferry; Okuyama, Kikuo

    2011-12-01

    Monodisperse spherical mesoporous silica nanoparticles were successfully synthesized using a liquid-phase synthesis method. The result showed particles with controllable pore size from several to tens nanometers with outer diameter of several tens nanometers. The ability in the control of pore size and outer diameter was altered by adjusting the precursor solution ratios. In addition, we have conducted the adsorption ability of the prepared particles. The result showed that large organic molecules were well-absorbed to the prepared silica porous particles, in which this result was not obtained when using commercial dense silica particle and/or hollow silica particle. With this result, the prepared mesoporous silica particles may be used efficiently in various applications, such as sensors, pharmaceuticals, environmentally sensitive pursuits, etc.

  13. Melting behavior of nanometer sized gold isomers

    NASA Astrophysics Data System (ADS)

    Liu, H. B.; Ascencio, J. A.; Perez-Alvarez, M.; Yacaman, M. J.

    2001-09-01

    In the present work, the melting behavior of nanometer sized gold isomers was studied using a tight-binding potential with a second momentum approximation. The cases of cuboctahedra, icosahedra, Bagley decahedra, Marks decahedra and star-like decahedra were considered. We calculated the temperature dependence of the total energy and volume during melting and the melting point for different types and sizes of clusters. In addition, the structural evolutions of the nanosized clusters during the melting transition were monitored and revealed. It is found that the melting process has three characteristic time periods for the intermediate nanosized clusters. The whole process includes surface disordering and reordering, followed by surface melting and a final rapid overall melting. This is a new observation, which it is in contrast with previous reports where surface melting is the dominant step.

  14. Synthesis of nanometer-size inorganic materials for the examination of particle size effects on heterogeneous catalysis

    NASA Astrophysics Data System (ADS)

    Emerson, Sean Christian

    The effect of acoustic and hydrodynamic cavitation on the precipitation of inorganic catalytic materials, specifically titania supported gold, was investigated. The overall objective was to understand the fundamental factors involved in synthesizing nanometer-size catalytic materials in the 1--10 nm range in a cavitating field. Materials with grain sizes in this range have been associated with enhanced catalytic activity compared to larger grain size materials. A new chemical approach was used to produce titania supported gold by co-precipitation with higher gold yields compared to other synthesis methods. Using this approach, it was determined that acoustic cavitation was unable to influence the gold mean crystallite size compared to non-sonicated catalysts. However, gold concentration on the catalysts was found to be very important for CO oxidation activity. By decreasing the gold concentration from a weight loading of 0.50% down to approximately 0.05%, the rate of reaction per mole of gold was found to increase by a factor of 19. Hydrodynamic cavitation at low pressures (6.9--48 bar) was determined to have no effect on gold crystallite size at a fixed gold content for the same precipitation technique used in the acoustic cavitation studies. By changing the chemistry of the precipitation system, however, it was found that a synergy existed between the dilution of the gold precursor solution, the orifice diameter, and the reducing agent addition rate. Individually, these factors were found to have little effect and only their interaction allowed gold grain size control in the range of 8--80 nm. Further modification of the system chemistry and the use of hydrodynamic cavitation at pressures in excess of 690 bar allowed the systematic control of gold crystallite size in the range of 2--9 nm for catalysts containing 2.27 +/- 0.17% gold. In addition, it was shown that the enhanced mixing due to cavitation led to larger gold yields compared to classical syntheses. The

  15. Wide size range fast integrated mobility spectrometer

    DOEpatents

    Wang, Jian

    2013-10-29

    A mobility spectrometer to measure a nanometer particle size distribution is disclosed. The mobility spectrometer includes a conduit and a detector. The conduit is configured to receive and provide fluid communication of a fluid stream having a charged nanometer particle mixture. The conduit includes a separator section configured to generate an electrical field of two dimensions transverse to a dimension associated with the flow of the charged nanometer particle mixture through the separator section to spatially separate charged nanometer particles of the charged nanometer particle mixture in said two dimensions. The detector is disposed downstream of the conduit to detect concentration and position of the spatially-separated nanometer particles.

  16. A new way to make diamond tip hosting an atomic sized defect

    NASA Astrophysics Data System (ADS)

    Zhou, Tony; Stohr, Rainer; Dovzhenko, Yuliya; Casola, Francesco; Yacoby, Amir

    The nitrogen-vacancy (NV) center in diamond has been fascinating people with its unique role in quantum information and magnetometry. NV magnetometry was used to investigate many fundamental physics studies and develop a number of industrial applications. One of the powerful aspects of NV magnetometry is the ability to scan in space to perform spatial magnetic field sensing with nano-meter resolution. As a new emerging scanning probe technique, it faces a huge challenge to be widely adopted due to its complexity in fabrication. Here, we report a new simple way of creating diamond tips with tools found in basic clean room facilities and mount the tips onto an experimental apparatus with common lab bench tools. Finally, scanning NV magnetometry was performed to demonstrate its application. This work is supported by the QuASAR project and the Gordon and Betty Moore Foundations EPiQS Initiative through Grant GBMF4531.

  17. Single Crystal Diamond Needle as Point Electron Source.

    PubMed

    Kleshch, Victor I; Purcell, Stephen T; Obraztsov, Alexander N

    2016-10-12

    Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2-0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics.

  18. Single Crystal Diamond Needle as Point Electron Source

    PubMed Central

    Kleshch, Victor I.; Purcell, Stephen T.; Obraztsov, Alexander N.

    2016-01-01

    Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2–0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics. PMID:27731379

  19. Single Crystal Diamond Needle as Point Electron Source

    NASA Astrophysics Data System (ADS)

    Kleshch, Victor I.; Purcell, Stephen T.; Obraztsov, Alexander N.

    2016-10-01

    Diamond has been considered to be one of the most attractive materials for cold-cathode applications during past two decades. However, its real application is hampered by the necessity to provide appropriate amount and transport of electrons to emitter surface which is usually achieved by using nanometer size or highly defective crystallites having much lower physical characteristics than the ideal diamond. Here, for the first time the use of single crystal diamond emitter with high aspect ratio as a point electron source is reported. Single crystal diamond needles were obtained by selective oxidation of polycrystalline diamond films produced by plasma enhanced chemical vapor deposition. Field emission currents and total electron energy distributions were measured for individual diamond needles as functions of extraction voltage and temperature. The needles demonstrate current saturation phenomenon and sensitivity of emission to temperature. The analysis of the voltage drops measured via electron energy analyzer shows that the conduction is provided by the surface of the diamond needles and is governed by Poole-Frenkel transport mechanism with characteristic trap energy of 0.2-0.3 eV. The temperature-sensitive FE characteristics of the diamond needles are of great interest for production of the point electron beam sources and sensors for vacuum electronics.

  20. Porous Architecture of SPS Thick YSZ Coatings Structured at the Nanometer Scale (~50 nm)

    NASA Astrophysics Data System (ADS)

    Bacciochini, Antoine; Montavon, Ghislain; Ilavsky, Jan; Denoirjean, Alain; Fauchais, Pierre

    2010-01-01

    Suspension plasma spraying (SPS) is a fairly recent technology that is able to process sub-micrometer-sized or nanometer-sized feedstock particles and permits the deposition of coatings thinner (from 20 to 100 μm) than those resulting from conventional atmospheric plasma spraying (APS). SPS consists of mechanically injecting within the plasma flow a liquid suspension of particles of average diameter varying between 0.02 and 1 μm. Due to the large volume fraction of the internal interfaces and reduced size of stacking defects, thick nanometer- or sub-micrometer-sized coatings exhibit better properties than conventional micrometer-sized ones (e.g., higher coefficients of thermal expansion, lower thermal diffusivity, higher hardness and toughness, better wear resistance, among other coating characteristics and functional properties). They could hence offer pertinent solutions to numerous emerging applications, particularly for energy production, energy saving, etc. Coatings structured at the nanometer scale exhibit nanometer-sized voids. Depending upon the selection of operating parameters, among which plasma power parameters (operating mode, enthalpy, spray distance, etc.), suspension properties (particle size distribution, powder mass percentage, viscosity, etc.), and substrate characteristics (topology, temperature, etc.), different coating architectures can be manufactured, from dense to porous layers, from connected to non-connected network. Nevertheless, the discrimination of porosity in different classes of criteria such as size, shape, orientation, specific surface area, etc., is essential to describe the coating architecture. Moreover, the primary steps of the coating manufacturing process affect significantly the coating porous architecture. These steps need to be further understood. Different types of imaging experiments were performed to understand, describe and quantify the pore level of thick finely structured ceramics coatings.

  1. Very High Efficiency, Miniaturized, Long-Lived Alpha Particle Power Source Using Diamond Devices for Extreme Space Environments

    NASA Technical Reports Server (NTRS)

    Kolawa, Elizabeth A. (Inventor); Patel, Jagdishbhai U. (Inventor); Fleurial, Jean-Pierre (Inventor)

    2004-01-01

    A power source that converts a-particle energy into electricity by coulomb collision in doped diamond films is described. Alpha particle decay from curium-244 creates electron-hole pairs by free- ing electrons and holes inside the crystal lattice in N- and P-doped diamond films. Ohmic contacts provide electrical connection to an electronic device. Due to the built-in electric field at the rectifying junction across the hT- and P-doped diamond films, the free electrons are constrained to traveling in generally one direction. This one direction then supplies electrons in a manner similar to that of a battery. The radioactive curium layer may be disposed on diamond films for even distribution of a-particle radiation. The resulting power source may be mounted on a diamond substrate that serves to insulate structures below the diamond substrate from a-particle emission. Additional insulation or isolation may be provided in order to prevent damage from a-particle collision. N-doped silicon may be used instead of N-doped diamond.

  2. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, G.W.; Roybal, H.E.

    1983-11-14

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al/sub 2/O/sub 3/ yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  3. Fluorinated diamond particles bonded in a filled fluorocarbon resin matrix

    DOEpatents

    Taylor, Gene W.; Roybal, Herman E.

    1985-01-01

    A method of producing fluorinated diamond particles bonded in a filled fluorocarbon resin matrix. Simple hot pressing techniques permit the formation of such matrices from which diamond impregnated grinding tools and other articles of manufacture can be produced. Teflon fluorocarbon resins filled with Al.sub.2 O.sub.3 yield grinding tools with substantially improved work-to-wear ratios over grinding wheels known in the art.

  4. Fabrication of diamond shells

    DOEpatents

    Hamza, Alex V.; Biener, Juergen; Wild, Christoph; Woerner, Eckhard

    2016-11-01

    A novel method for fabricating diamond shells is introduced. The fabrication of such shells is a multi-step process, which involves diamond chemical vapor deposition on predetermined mandrels followed by polishing, microfabrication of holes, and removal of the mandrel by an etch process. The resultant shells of the present invention can be configured with a surface roughness at the nanometer level (e.g., on the order of down to about 10 nm RMS) on a mm length scale, and exhibit excellent hardness/strength, and good transparency in the both the infra-red and visible. Specifically, a novel process is disclosed herein, which allows coating of spherical substrates with optical-quality diamond films or nanocrystalline diamond films.

  5. NANOMETER DIESEL EXHAUST PARTICLES ARE NEUROTOXIC TO DOPAMINERGIC NEURONS THROUGH MICROGLIAL ACTIVATION.

    EPA Science Inventory

    NANOMETER DIESEL EXHAUST PARTICLES ARE NEUROTOXIC TO DOPAMINERGIC NEURONS THROUGH MICROGLIAL ACTIVATION. M.L. Block1,2, X. Wu1, P. Zhong1, G. Li1, T. Wang1, J.S. Hong1 & B.Veronesi.2
    1The Laboratory of Pharmacology and Chemistry, NIEHS, RTP, NC and 2 National Health and Envi...

  6. Micrometer- and nanometer-sized platinum group nuggets in micrometeorites from deep-sea sediments of the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Parashar, K.; Shyam Prasad, M.

    2011-03-01

    We examined 378 micrometeorites collected from deep-sea sediments of the Indian Ocean of which 175, 180, and 23 are I-type, S-type, and G-type, respectively. Of the 175 I-type spherules, 13 contained platinum group element nuggets (PGNs). The nuggets occur in two distinct sizes and have distinctly different elemental compositions: micrometer (μm)-sized nuggets that are >3 μm contain dominantly Ir, Os, and Ru (iridium-platinum group element or IPGE) and sub-μm (or nanometer)-sized (<1 μm) nuggets, which contain dominantly Pt, Rh, and Pd (palladium—PGE or PPGE). The μm-sized nuggets are found only one per spherule in the cross section observed and are usually found at the edge of the spherule. By contrast, there are hundreds of nanometer-sized nuggets distributed dominantly in the magnetite phases of the spherules, and rarely in the wüstite phases. Both the nugget types are found as separate entities in the same spherule and apparently, nugget formation is a common phenomenon among I-type micrometeorites. However, the μm-sized nuggets are seen in fewer specimens (˜2.5% of the observed I-type spherules). In all, we analyzed four nuggets of μm size and 213 nanometer-sized nuggets from 13 I-type spherules for platinum group elements. Chemically, the μm-sized PGNs contain chondritic ratios of Os/Ir, but are depleted in the more volatile PGE (Pt, Rh, and Pd) relative to chondritic ratios. On the other hand, the nanometer-sized nuggets contain dominantly Pt and Rh. Importantly, the refractory PGEs are conspicuous by their absence in these nanometer nuggets. Palladium, the most volatile PGE is highly depleted (<1.1%) with respect to chondritic ratios in the μm-sized PGNs, and is observed in only 17 of 213 nanometer nuggets with concentrations that are just above the detection limit (≥0.2%). Distinct fractionation of the PGE into IPGE (Ir, Os, Ru) and PPGE seems to take place during the short span of atmospheric entry. These observations suggest several

  7. Low substrate temperature deposition of diamond coatings derived from glassy carbon

    DOEpatents

    Holcombe, Jr., Cressie E.; Seals, Roland D.

    1995-01-01

    A process for depositing a diamond coating on a substrate at temperatures less than about 550.degree. C. A powder mixture of glassy carbon and diamond particles is passed through a high velocity oxy-flame apparatus whereupon the powders are heated prior to impingement at high velocity against the substrate. The powder mixture contains between 5 and 50 powder volume percent of the diamond particles, and preferably between 5 and 15 powder volume percent. The particles have a size from about 5 to about 100 micrometers, with the diamond particles being about 5 to about 30 micrometers. The flame of the apparatus provides a velocity of about 350 to about 1000 meters per second, with the result that upon impingement upon the substrate, the glassy carbon is phase transformed to diamond as coaxed by the diamond content of the powder mixture.

  8. A comparison of two nano-sized particle air filtration tests in the diameter range of 10 to 400 nanometers

    NASA Astrophysics Data System (ADS)

    Japuntich, Daniel A.; Franklin, Luke M.; Pui, David Y.; Kuehn, Thomas H.; Kim, Seong Chan; Viner, Andrew S.

    2007-01-01

    Two different air filter test methodologies are discussed and compared for challenges in the nano-sized particle range of 10-400 nm. Included in the discussion are test procedure development, factors affecting variability and comparisons between results from the tests. One test system which gives a discrete penetration for a given particle size is the TSI 8160 Automated Filter tester (updated and commercially available now as the TSI 3160) manufactured by the TSI, Inc., Shoreview, MN. Another filter test system was developed utilizing a Scanning Mobility Particle Sizer (SMPS) to sample the particle size distributions downstream and upstream of an air filter to obtain a continuous percent filter penetration versus particle size curve. Filtration test results are shown for fiberglass filter paper of intermediate filtration efficiency. Test variables affecting the results of the TSI 8160 for NaCl and dioctyl phthalate (DOP) particles are discussed, including condensation particle counter stability and the sizing of the selected particle challenges. Filter testing using a TSI 3936 SMPS sampling upstream and downstream of a filter is also shown with a discussion of test variables and the need for proper SMPS volume purging and filter penetration correction procedure. For both tests, the penetration versus particle size curves for the filter media studied follow the theoretical Brownian capture model of decreasing penetration with decreasing particle diameter down to 10 nm with no deviation. From these findings, the authors can say with reasonable confidence that there is no evidence of particle thermal rebound in the size range.

  9. Particle size analysis of amalgam powder and handpiece generated specimens.

    PubMed

    Drummond, J L; Hathorn, R M; Cailas, M D; Karuhn, R

    2001-07-01

    The increasing interest in the elimination of amalgam particles from the dental waste (DW) stream, requires efficient devices to remove these particles. The major objective of this project was to perform a comparative evaluation of five basic methods of particle size analysis in terms of the instrument's ability to quantify the size distribution of the various components within the DW stream. The analytical techniques chosen were image analysis via scanning electron microscopy, standard wire mesh sieves, X-ray sedigraphy, laser diffraction, and electrozone analysis. The DW particle stream components were represented by amalgam powders and handpiece/diamond bur generated specimens of enamel; dentin, whole tooth, and condensed amalgam. Each analytical method quantified the examined DW particle stream components. However, X-ray sedigraphy, electrozone, and laser diffraction particle analyses provided similar results for determining particle distributions of DW samples. These three methods were able to more clearly quantify the properties of the examined powder and condensed amalgam samples. Furthermore, these methods indicated that a significant fraction of the DW stream contains particles less than 20 microm. The findings of this study indicated that the electrozone method is likely to be the most effective technique for quantifying the particle size distribution in the DW particle stream. This method required a relative small volume of sample, was not affected by density, shape factors or optical properties, and measured a sufficient number of particles to provide a reliable representation of the particle size distribution curve.

  10. Nanometer-scale sizing accuracy of particle suspensions on an unmodified cell phone using elastic light scattering.

    PubMed

    Smith, Zachary J; Chu, Kaiqin; Wachsmann-Hogiu, Sebastian

    2012-01-01

    We report on the construction of a Fourier plane imaging system attached to a cell phone. By illuminating particle suspensions with a collimated beam from an inexpensive diode laser, angularly resolved scattering patterns are imaged by the phone's camera. Analyzing these patterns with Mie theory results in predictions of size distributions of the particles in suspension. Despite using consumer grade electronics, we extracted size distributions of sphere suspensions with better than 20 nm accuracy in determining the mean size. We also show results from milk, yeast, and blood cells. Performing these measurements on a portable device presents opportunities for field-testing of food quality, process monitoring, and medical diagnosis.

  11. [Study of relationship between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite powder].

    PubMed

    Chai, Feng; Xu, Ling; Liao, Yun-mao; Chao, Yong-lie

    2003-07-01

    The fabrication of all-ceramic dental restorations is challenged by ceramics' relatively low flexural strength and intrinsic poor resistance to fracture. This paper aimed at investigating the relationships between powder-size gradation and mechanical properties of Zirconia toughened glass infiltrated nanometer-ceramic composite (Al(2)O(3)-nZrO(2)). Al(2)O(3)-nZrO(2) ceramics powder (W) was processed by combination methods of chemical co-precipitation and ball milling with addition of different powder-sized ZrO(2). Field-emission scanning electron microscopy was used to determine the particle size distribution and characterize the particle morphology of powders. The matrix compacts were made by slip-casting technique and sintered to 1,450 degrees C and flexural strength and the fracture toughness of them were measured. 1. The particle distribution of Al(2)O(3)-nZrO(2) ceramics powder ranges from 0.02 - 3.5 micro m and among them the superfine particles almost accounted for 20%. 2. The ceramic matrix samples with addition of nZrO(2) (W) showed much higher flexural strength (115.434 +/- 5.319) MPa and fracture toughness (2.04 +/- 0.10) MPa m(1/2) than those of pure Al(2)O(3) ceramics (62.763 +/- 7.220 MPa; 1.16 +/- 0.02 MPa m(1/2)). The particle size of additive ZrO(2) may impose influences on mechanical properties of Al(2)O(3)-nZrO(2) ceramics matrix. Good homogeneity and reasonable powder-size gradation of ceramic powder can improve the mechanical properties of material.

  12. Characterization of CVD micrometer-size diamond (abstract)

    NASA Astrophysics Data System (ADS)

    Ohsumi, K.; Hagiya, K.; Miyamoto, M.; Matsuda, J.; Ohmasa, M.

    1989-07-01

    In the field of material sciences, it has long been desired to develope the equipment to obtain crystallographic information of micrometer-size crystalline substances. Synchrotron radiation (SR) could be a candidate to deal with such a small specimen other than electron microscope. It seems more advantageous to utilize SR from the viewpoint that the processing of the diffraction data that has already been established for identification of the materials, structure analysis, and refinement. Even in the case of SR, special care should be taken for the measurement of very weak diffracted intensities. In the case not using SR, the size of 50 μm might be the limit for the specimen to be examined by the diffraction method. The diffracted intensity is proportional to the volume of the specimen, and that of micrometer-size crystal is estimated as 10-5 times of that of the limit mentioned above. The noise level of the experiment, therefore, should be as low as possible. If the noise level becomes negligibly small, the signal could be accumulated continually to the desired intensity level by adjusting measuring time. The experiment, for the purpose, should be carried out in vacuum with the stational crystal method and with very narrow collimated x-ray beams. The Laue method is employed by the above reason, as well as the fact that the intensity of each Bragg reflection on a reciprocal row passing through the origin of the reciprocal space is superposed with each other, which also intensifies a diffraction spot on the photographic plate. The Laue camera is set up at BL-4B of Photon Factory, sealed in vacuum and installed with a very narrow collimater. The development of the system has been performed to the level which several Bragg reflections of molybdenum single crystal with 0.8 μm in its diameter can be taken on the imaging plate for 50-min exposure with ring current from 128 to 125 mA. The origin of diamonds in meteorites has been a controversy as to whether they are

  13. Low substrate temperature deposition of diamond coatings derived from glassy carbon

    DOEpatents

    Holcombe, C.E. Jr.; Seals, R.D.

    1995-09-26

    A process is disclosed for depositing a diamond coating on a substrate at temperatures less than about 550 C. A powder mixture of glassy carbon and diamond particles is passed through a high velocity oxy-flame apparatus whereupon the powders are heated prior to impingement at high velocity against the substrate. The powder mixture contains between 5 and 50 powder volume percent of the diamond particles, and preferably between 5 and 15 powder volume percent. The particles have a size from about 5 to about 100 micrometers, with the diamond particles being about 5 to about 30 micrometers. The flame of the apparatus provides a velocity of about 350 to about 1000 meters per second, with the result that upon impingement upon the substrate, the glassy carbon is phase transformed to diamond as coaxed by the diamond content of the powder mixture. 2 figs.

  14. DNA-linked NanoParticle Lattices with Diamond Symmetry: Stability, Shape and Optical Properties

    NASA Astrophysics Data System (ADS)

    Emamy, Hamed; Tkachenko, Alexei; Gang, Oleg; Starr, Francis

    The linking of nanoparticles (NP) by DNA has been proven to be an effective means to create NP lattices with specific order. Lattices with diamond symmetry are predicted to offer novel photonic properties, but self-assembly of such lattices has proven to be challenging due to the low packing fraction, sensitivity to bond orientation, and local heterogeneity. Recently, we reported an approach to create diamond NP lattices based on the association between anisotropic particles with well-defined tetravalent DNA binding topology and isotropically functionalized NP. Here, we use molecular dynamics simulations to evaluate the Gibbs free energy of these lattices, and thereby determine the stability of these lattices as a function of NP size and DNA stiffness. We also predict the equilibrium shape for the cubic diamond crystallite using the Wulff construction method. Specifically, we predict the equilibrium shape using the surface energy for different crystallographic planes. We evaluate surface energy directly form molecular dynamics simulation, which we correlate with theoretical estimates from the expected number of broken DNA bonds along a facet. Furthermore we study the optical properties of this structure, e.g optical bandgap.

  15. Direct observation of terahertz surface modes in nanometer-sized liquid water pools.

    PubMed

    Boyd, J E; Briskman, A; Colvin, V L; Mittleman, D M

    2001-10-01

    The far-infrared absorption spectrum of nanometer-sized water pools at the core of AOT micelles exhibits a pronounced resonance which is absent in bulk water. The amplitude and spectral position of this resonance are sensitive to the size of the confined water core. This resonance results from size-dependent modifications in the vibrational density of states, and thus has far-reaching implications for chemical processes which involve water sequestered within small cavities. These data represent the first study of the terahertz dielectric properties of confined liquids.

  16. Molecular dynamics simulations of shock compressed heterogeneous materials. II. The graphite/diamond transition case for astrophysics applications

    NASA Astrophysics Data System (ADS)

    Pineau, N.; Soulard, L.; Colombet, L.; Carrard, T.; Pellé, A.; Gillet, Ph.; Clérouin, J.

    2015-03-01

    We present a series of molecular dynamics simulations of the shock compression of copper matrices containing a single graphite inclusion: these model systems can be related to some specific carbon-rich rocks which, after a meteoritic impact, are found to contain small fractions of nanodiamonds embedded in graphite in the vicinity of high impedance minerals. We show that the graphite to diamond transformation occurs readily for nanometer-sized graphite inclusions, via a shock accumulation process, provided the pressure threshold of the bulk graphite/diamond transition is overcome, independently of the shape or size of the inclusion. Although high diamond yields (˜80%) are found after a few picoseconds in all cases, the transition is non-isotropic and depends substantially on the relative orientation of the graphite stack with respect to the shock propagation, leading to distinct nucleation processes and size-distributions of the diamond grains. A substantial regraphitization process occurs upon release and only inclusions with favorable orientations likely lead to the preservation of a fraction of this diamond phase. These results agree qualitatively well with the recent experimental observations of meteoritic impact samples.

  17. Size and shape effects on diffusion and absorption of colloidal particles near a partially absorbing sphere: implications for uptake of nanoparticles in animal cells.

    PubMed

    Shi, Wendong; Wang, Jizeng; Fan, Xiaojun; Gao, Huajian

    2008-12-01

    A mechanics model describing how a cell membrane with diffusive mobile receptors wraps around a ligand-coated cylindrical or spherical particle has been recently developed to model the role of particle size in receptor-mediated endocytosis. The results show that particles in the size range of tens to hundreds of nanometers can enter cells even in the absence of clathrin or caveolin coats. Here we report further progress on modeling the effects of size and shape in diffusion, interaction, and absorption of finite-sized colloidal particles near a partially absorbing sphere. Our analysis indicates that, from the diffusion and interaction point of view, there exists an optimal hydrodynamic size of particles, typically in the nanometer regime, for the maximum rate of particle absorption. Such optimal size arises as a result of balance between the diffusion constant of the particles and the interaction energy between the particles and the absorbing sphere relative to the thermal energy. Particles with a smaller hydrodynamic radius have larger diffusion constant but weaker interaction with the sphere while larger particles have smaller diffusion constant but stronger interaction with the sphere. Since the hydrodynamic radius is also determined by the particle shape, an optimal hydrodynamic radius implies an optimal size as well as an optimal aspect ratio for a nonspherical particle. These results show broad agreement with experimental observations and may have general implications on interaction between nanoparticles and animal cells.

  18. Size and shape effects on diffusion and absorption of colloidal particles near a partially absorbing sphere: Implications for uptake of nanoparticles in animal cells

    NASA Astrophysics Data System (ADS)

    Shi, Wendong; Wang, Jizeng; Fan, Xiaojun; Gao, Huajian

    2008-12-01

    A mechanics model describing how a cell membrane with diffusive mobile receptors wraps around a ligand-coated cylindrical or spherical particle has been recently developed to model the role of particle size in receptor-mediated endocytosis. The results show that particles in the size range of tens to hundreds of nanometers can enter cells even in the absence of clathrin or caveolin coats. Here we report further progress on modeling the effects of size and shape in diffusion, interaction, and absorption of finite-sized colloidal particles near a partially absorbing sphere. Our analysis indicates that, from the diffusion and interaction point of view, there exists an optimal hydrodynamic size of particles, typically in the nanometer regime, for the maximum rate of particle absorption. Such optimal size arises as a result of balance between the diffusion constant of the particles and the interaction energy between the particles and the absorbing sphere relative to the thermal energy. Particles with a smaller hydrodynamic radius have larger diffusion constant but weaker interaction with the sphere while larger particles have smaller diffusion constant but stronger interaction with the sphere. Since the hydrodynamic radius is also determined by the particle shape, an optimal hydrodynamic radius implies an optimal size as well as an optimal aspect ratio for a nonspherical particle. These results show broad agreement with experimental observations and may have general implications on interaction between nanoparticles and animal cells.

  19. Fabrication of a single sub-micron pore spanning a single crystal (100) diamond membrane and impact on particle translocation [Particle translocation through a single crystal diamond pore fabricated by electron beam induced chemical etching

    DOE PAGES

    Webb, Jennifer R.; Martin, Aiden A.; Johnson, Robert P.; ...

    2017-06-21

    The fabrication of sub-micron pores in single crystal diamond membranes, which span the entirety of the membrane, is described for the first time, and the translocation properties of polymeric particles through the pore investigated. The pores are produced using a combination of laser micromachining to form the membrane and electron beam induced etching to form the pore. Single crystal diamond as the membrane material, has the advantages of chemical stability and durability, does not hydrate and swell, has outstanding electrical properties that facilitate fast, low noise current-time measurements and is optically transparent for combined optical-conductance sensing. The resulting pores aremore » characterized individually using both conductance measurements, employing a microcapillary electrochemical setup, and electron microscopy. Proof-of-concept experiments to sense charged polystyrene particles as they are electrophoretically driven through a single diamond pore are performed, and the impact of this new pore material on particle translocation is explored. As a result, these findings reveal the potential of diamond as a platform for pore-based sensing technologies and pave the way for the fabrication of single nanopores which span the entirety of a diamond membrane.« less

  20. Fabrication of a single sub-micron pore spanning a single crystal (100) diamond membrane and impact on particle translocation [Particle translocation through a single crystal diamond pore fabricated by electron beam induced chemical etching

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

    Webb, Jennifer R.; Martin, Aiden A.; Johnson, Robert P.

    The fabrication of sub-micron pores in single crystal diamond membranes, which span the entirety of the membrane, is described for the first time, and the translocation properties of polymeric particles through the pore investigated. The pores are produced using a combination of laser micromachining to form the membrane and electron beam induced etching to form the pore. Single crystal diamond as the membrane material, has the advantages of chemical stability and durability, does not hydrate and swell, has outstanding electrical properties that facilitate fast, low noise current-time measurements and is optically transparent for combined optical-conductance sensing. The resulting pores aremore » characterized individually using both conductance measurements, employing a microcapillary electrochemical setup, and electron microscopy. Proof-of-concept experiments to sense charged polystyrene particles as they are electrophoretically driven through a single diamond pore are performed, and the impact of this new pore material on particle translocation is explored. As a result, these findings reveal the potential of diamond as a platform for pore-based sensing technologies and pave the way for the fabrication of single nanopores which span the entirety of a diamond membrane.« less

  1. Three-dimensional integrated circuits for lab-on-chip dielectrophoresis of nanometer scale particles

    NASA Astrophysics Data System (ADS)

    Dickerson, Samuel J.; Noyola, Arnaldo J.; Levitan, Steven P.; Chiarulli, Donald M.

    2007-01-01

    In this paper, we present a mixed-technology micro-system for electronically manipulating and optically detecting virusscale particles in fluids that is designed using 3D integrated circuit technology. During the 3D fabrication process, the top-most chip tier is assembled upside down and the substrate material is removed. This places the polysilicon layer, which is used to create geometries with the process' minimum feature size, in close proximity to a fluid channel etched into the top of the stack. By taking advantage of these processing features inherent to "3D chip-stacking" technology, we create electrode arrays that have a gap spacing of 270 nm. Using 3D CMOS technology also provides the ability to densely integrate analog and digital control circuitry for the electrodes by using the additional levels of the chip stack. We show simulations of the system with a physical model of a Kaposi's sarcoma-associated herpes virus, which has a radius of approximately 125 nm, being dielectrophoretically arranged into striped patterns. We also discuss how these striped patterns of trapped nanometer scale particles create an effective diffraction grating which can then be sensed with macro-scale optical techniques.

  2. Peculiarities of both light and beta-particles scattering by ultrathin diamond-like semiconductor film.

    PubMed

    Rumyantsev, Vladimir V; Shtaerman, Esfir Y

    2008-02-01

    Peculiarities of scattering of TM-polarized light wave by a diamond-like crystalline nano-layer are studied. They are due to specific dispersion of n-phonon polaritons localized in the layer. The IR polaritons discussed here (relating to diamond and Si crystals which are nonpolar materials) will only appear if some of the vibration modes become polar, e.g., due to the presence of the surface. As a result of mixing of g- and u-modes of ion oscillations along the (111)-direction in the near-surface layer, it is possible to observe additional (with respect to bulk) scattering of coherent electromagnetic waves of the Stokes and anti-Stokes frequencies. beta-particles can be utilized as an independent tool of study of new semiconductors, in particular thin diamond films. The effect associated with response of a quasi-two-dimensional diamond-like layer to the moving electron field is considered. beta-particle field induces phonon excitation modes to arise in the material. Coupled with the beta-particle electromagnetic modes they generate polaritons. Spectral density of the radiation intensity of the flashed phonon polaritons has been estimated as a function of the layer thickness as well as of the scattering angle and the beta-particle velocity.

  3. PTW-diamond detector: dose rate and particle type dependence.

    PubMed

    Fidanzio, A; Azario, L; Miceli, R; Russo, A; Piermattei, A

    2000-11-01

    In this paper the suitability of a PTW natural diamond detector (DD) for relative and reference dosimetry of photon and electron beams, with dose per pulse between 0.068 mGy and 0.472 mGy, was studied and the results were compared with those obtained by a stereotactic silicon detector (SFD). The results show that, in the range of the examined dose per pulse the DD sensitivity changes up to 1.8% while the SFD sensitivity changes up to 4.5%. The fitting parameter, delta, used to correct the dose per pulse dependence of solid state detectors, was delta = 0.993 +/- 0.002 and delta = 1.025 +/- 0.002 for the diamond detector and for the silicon diode, respectively. The delta values were found to be independent of particle type of two conventional beams (a 10 MV x-ray beam and a 21 MeV electron beam). So if delta is determined for a radiotherapy beam, it can be used to correct relative dosimetry for other conventional radiotherapy beams. Moreover the diamond detector shows a calibration factor which is independent of beam quality and particle type, so an empirical dosimetric formalism is proposed here to obtain the reference dosimetry. This formalism is based on a dose-to-water calibration factor and on an empirical coefficient, that takes into account the reading dependence on the dose per pulse.

  4. Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines

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

    Qafoku, Odeta; Ilton, Eugene S.; Bowden, Mark E.

    Olivines are divalent orthosilicates with important geologic, biological, and industrial significance and are typically comprised of mixtures of Mg2+ and Fe2+ ranging from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Investigating the role of Fe(II) in olivine reactivity requires the ability to synthesize olivines that are nanometer-sized, have different percentages of Mg2+ and Fe2+, and have good bulk and surface purity. This article demonstrates a new method for synthesizing nanosized fayalite and Mg-Fe mixture olivines. First, carbonaceous precursors are generated from sucrose, PVA, colloidal silica, Mg2+, and Fe3+. Second, these precursors are calcined in air to burn carbon and create mixtures ofmore » Fe(III)-oxides, forsterite, and SiO2. Finally, calcination in reducing CO-CO2 gas buffer leads to Fe(II)-rich olivines. XRD, Mössbauer, and IR analyses verify good bulk purity and composition. XPS indicates that surface iron is in its reduced Fe(II) form, and surface Si is consistent with olivine. SEM shows particle sizes predominately between 50 and 450 nm, and BET surface areas are 2.8-4.2 m2/g. STEM HAADF analysis demonstrates even distributions of Mg and Fe among the available M1 and M2 sites of the olivine crystals. These nanosized Fe(II)-rich olivines are suitable for laboratory studies with in situ probes that require mineral samples with high reactivity at short timescales.« less

  5. Abrasion of eroded and sound enamel by a dentifrice containing diamond abrasive particles

    PubMed

    Wegehaupt, Florian J.; Hoegger, Vanessa G. M.; Attin, Thomas

    2017-07-24

    Eroded enamel is more susceptible to abrasive wear than sound enamel. New toothpastes utilizing diamond particles as abrasives have been developed. The present study investigated the abrasive wear of eroded enamel by three commercially available toothpastes (one containing diamond particles) and compared it to the respective wear of sound enamel caused by these toothpastes. Seventy-two bovine enamel samples were randomly allocated to six groups (S1–S3 and E1–E3; n=12). Samples were submitted to an abrasive (S1–S3) or erosion plus abrasion (E1–E3) cycling. Per cycle, all samples were brushed (abrasion; 20 brushing stokes) with the following toothpastes: S1/E1: Signal WHITE SYSTEM, S2/E2: elmex KARIESSCHUTZ and S3-E3: Candida WHITE DIAMOND (diamond particles). Groups E1–E3 were additionally eroded with HCl (pH 3.0) for 2 min before each brushing procedure. After 30, 60 and 90 cycles enamel wear was measured by surface profilometry. Within the same toothpaste and same number of cycles, enamel wear due to erosion plus abrasion was significantly higher than due to mere abrasion. After 30, 60 and 90 cycles, no significant difference in the wear in groups S1 and S2 was observed while the wear in group E1 was significantly (p<0.05, ANOVA, Scheffecyc) lower than that in group E2. After 90 cycles, wear in group S3 was about 5 times higher than that in group S2, while wear in group E3 was about 1.3 times higher than that in group E2. As compared to the other two investigated toothpastes, the dentifrice containing diamond particles caused slightly higher abrasive wear of eroded enamel and distinctly higher wear of sound enamel compared to the conventional toothpastes under investigation.

  6. Enamel subsurface damage due to tooth preparation with diamonds.

    PubMed

    Xu, H H; Kelly, J R; Jahanmir, S; Thompson, V P; Rekow, E D

    1997-10-01

    In clinical tooth preparation with diamond burs, sharp diamond particles indent and scratch the enamel, causing material removal. Such operations may produce subsurface damage in enamel. However, little information is available on the mechanisms and the extent of subsurface damage in enamel produced during clinical tooth preparation. The aim of this study, therefore, was to investigate the mechanisms of subsurface damage produced in enamel during tooth preparation by means of diamond burs, and to examine the dependence of such damage on enamel rod orientation, diamond particle size, and removal rate. Subsurface damage was evaluated by a bonded-interface technique. Tooth preparation was carried out on two enamel rod orientations, with four clinical diamond burs (coarse, medium, fine, and superfine) used in a dental handpiece. The results of this study showed that subsurface damage in enamel took the form of median-type cracks and distributed microcracks, extending preferentially along the boundaries between the enamel rods. Microcracks within individual enamel rods were also observed. The median-type cracks were significantly longer in the direction parallel to the enamel rods than perpendicular to the rods. Preparation with the coarse diamond bur produced cracks as deep as 84 +/- 30 microns in enamel. Finishing with fine diamond burs was effective in crack removal. The crack lengths in enamel were not significantly different when the removal rate was varied. Based on these results, it is concluded that subsurface damage in enamel induced by tooth preparation takes the form of median-type cracks as well as inter- and intra-rod microcracks, and that the lengths of these cracks are sensitive to diamond particle size and enamel rod orientation, but insensitive to removal rate.

  7. Morphological Transition in Diamond Thin-Films Induced by Boron in a Microwave Plasma Deposition Process.

    PubMed

    Baker, Paul A; Goodloe, David R; Vohra, Yogesh K

    2017-11-14

    The purpose of this study is to understand the basic mechanisms responsible for the synthesis of nanostructured diamond films in a microwave plasma chemical vapor deposition (MPCVD) process and to identify plasma chemistry suitable for controlling the morphology and electrical properties of deposited films. The nanostructured diamond films were synthesized by MPCVD on Ti-6Al-4V alloy substrates using H₂/CH₄/N₂ precursor gases and the plasma chemistry was monitored by the optical emission spectroscopy (OES). The synthesized thin-films were characterized by x -ray diffraction and scanning electron microscopy. The addition of B₂H₆ to the feedgas during MPCVD of diamond thin-films changes the crystal grain size from nanometer to micron scale. Nanostructured diamond films grown with H₂/CH₄/N₂ gases demonstrate a broad (111) Bragg x -ray diffraction peak (Full-Width at Half-Maximum (FWHM) = 0.93° 2θ), indicating a small grain size, whereas scans show a definite sharpening of the diamond (111) peak (FWHM = 0.30° 2θ) with the addition of boron. OES showed a decrease in CN (carbon-nitrogen) radical in the plasma with B₂H₆ addition to the gas mixture. Our study indicates that CN radical plays a critical role in the synthesis of nanostructured diamond films and suppression of CN radical by boron-addition in the plasma causes a morphological transition to microcrystalline diamond.

  8. Single crystal diamond membranes for nanoelectronics.

    PubMed

    Bray, Kerem; Kato, Hiromitsu; Previdi, Rodolfo; Sandstrom, Russell; Ganesan, Kumaravelu; Ogura, Masahiko; Makino, Toshiharu; Yamasaki, Satoshi; Magyar, Andrew P; Toth, Milos; Aharonovich, Igor

    2018-02-22

    Single crystal, nanoscale diamond membranes are highly sought after for a variety of applications including nanophotonics, nanoelectronics and quantum information science. However, so far, the availability of conductive diamond membranes has remained an unreachable goal. In this work we present a complete nanofabrication methodology for engineering high aspect ratio, electrically active single crystal diamond membranes. The membranes have large lateral directions, exceeding ∼500 × 500 μm 2 and are only several hundreds of nanometers thick. We further realize vertical single crystal p-n junctions made from the diamond membranes that exhibit onset voltages of ∼10 V and a current of several mA. Moreover, we deterministically introduce optically active color centers into the membranes, and demonstrate for the first time a single crystal nanoscale diamond LED. The robust and scalable approach to engineer the electrically active single crystal diamond membranes offers new pathways for advanced nanophotonic, nanoelectronic and optomechanical devices employing diamond.

  9. The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry.

    PubMed

    Noya, Eva G; Vega, Carlos; Doye, Jonathan P K; Louis, Ard A

    2010-06-21

    The phase diagram of model anisotropic particles with four attractive patches in a tetrahedral arrangement has been computed at two different values of the range of the potential, with the aim of investigating the conditions under which a diamond crystal can be formed. We find that the diamond phase is never stable for our longer-ranged potential. At low temperatures and pressures, the fluid freezes into a body-centered-cubic solid that can be viewed as two interpenetrating diamond lattices with a weak interaction between the two sublattices. Upon compression, an orientationally ordered face-centered-cubic crystal becomes more stable than the body-centered-cubic crystal, and at higher temperatures, a plastic face-centered-cubic phase is stabilized by the increased entropy due to orientational disorder. A similar phase diagram is found for the shorter-ranged potential, but at low temperatures and pressures, we also find a region over which the diamond phase is thermodynamically favored over the body-centered-cubic phase. The higher vibrational entropy of the diamond structure with respect to the body-centered-cubic solid explains why it is stable even though the enthalpy of the latter phase is lower. Some preliminary studies on the growth of the diamond structure starting from a crystal seed were performed. Even though the diamond phase is never thermodynamically stable for the longer-ranged model, direct coexistence simulations of the interface between the fluid and the body-centered-cubic crystal and between the fluid and the diamond crystal show that at sufficiently low pressures, it is quite probable that in both cases the solid grows into a diamond crystal, albeit involving some defects. These results highlight the importance of kinetic effects in the formation of diamond crystals in systems of patchy particles.

  10. Removal of 10-nm contaminant particles from Si wafers using CO2 bullet particles.

    PubMed

    Kim, Inho; Hwang, Kwangseok; Lee, Jinwon

    2012-04-11

    Removal of nanometer-sized contaminant particles (CPs) from substrates is essential in successful fabrication of nanoscale devices. The particle beam technique that uses nanometer-sized bullet particles (BPs) moving at supersonic velocity was improved by operating it at room temperature to achieve higher velocity and size uniformity of BPs and was successfully used to remove CPs as small as 10 nm. CO2 BPs were generated by gas-phase nucleation and growth in a supersonic nozzle; appropriate size and velocity of the BPs were obtained by optimizing the nozzle contours and CO2/He mixture fraction. Cleaning efficiency greater than 95% was attained. BP velocity was the most important parameter affecting removal of CPs in the 10-nm size range. Compared to cryogenic Ar or N2 particles, CO2 BPs were more uniform in size and had higher velocity and, therefore, cleaned CPs more effectively.

  11. Fluidized bed deposition of diamond

    DOEpatents

    Laia, Jr., Joseph R.; Carroll, David W.; Trkula, Mitchell; Anderson, Wallace E.; Valone, Steven M.

    1998-01-01

    A process for coating a substrate with diamond or diamond-like material including maintaining a substrate within a bed of particles capable of being fluidized, the particles having substantially uniform dimensions and the substrate characterized as having different dimensions than the bed particles, fluidizing the bed of particles, and depositing a coating of diamond or diamond-like material upon the substrate by chemical vapor deposition of a carbon-containing precursor gas mixture, the precursor gas mixture introduced into the fluidized bed under conditions resulting in excitation mechanisms sufficient to form the diamond coating.

  12. Graphite to ultrafine nanocrystalline diamond phase transition model and growth restriction mechanism induced by nanosecond laser processing

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

    Ren, X. D., E-mail: renxd@mail.ujs.edu.cn; Liu, R.; Zheng, L. M.

    2015-10-05

    To have a clear insight into nanocrystal growth from graphite to diamond upon high energy pulsed laser irradiation of graphite suspension, synthesis of ultrafine nanocrystalline diamonds with laser energy set up from 0.3 J to 12 J, repetition rate of 10 Hz has been studied. The method allows synthesizing ultrafine nanocrystalline particles continuously at the ambient temperature and normal pressure. The particle size is shown independent of laser energy, which is ultrafine and ranges in 2–6 nm. The theoretical grown size of nano-diamonds is found in well agreement with the experiment results. Four kinds of production were found: nano-diamond, spherical carbon nano-particles, flocculent amorphousmore » carbon, and graphene nano-ribbon rolls. A solid-vapor-plasma-liquid coexistence model describing phase transition from graphite to diamond induced by nanosecond laser processing was proposed. Graphene nano-ribbon rolls might be the intermediate phase in the conversion from graphite to diamond.« less

  13. Method to grow pure nanocrystalline diamond films at low temperatures and high deposition rates

    DOEpatents

    Carlisle, John A [Plainfield, IL; Gruen, Dieter M [Downers Grove, IL; Auciello, Orlando [Bolingbrook, IL; Xiao, Xingcheng [Woodridge, IL

    2009-07-07

    A method of depositing nanocrystalline diamond film on a substrate at a rate of not less than about 0.2 microns/hour at a substrate temperature less than about 500.degree. C. The method includes seeding the substrate surface with nanocrystalline diamond powder to an areal density of not less than about 10.sup.10sites/cm.sup.2, and contacting the seeded substrate surface with a gas of about 99% by volume of an inert gas other than helium and about 1% by volume of methane or hydrogen and one or more of acetylene, fullerene and anthracene in the presence of a microwave induced plasma while maintaining the substrate temperature less than about 500.degree. C. to deposit nanocrystalline diamond on the seeded substrate surface at a rate not less than about 0.2 microns/hour. Coatings of nanocrystalline diamond with average particle diameters of less than about 20 nanometers can be deposited with thermal budgets of 500.degree. C.-4 hours or less onto a variety of substrates such as MEMS devices.

  14. Effect of TiO2/Al2O3 film coated diamond abrasive particles by sol-gel technique

    NASA Astrophysics Data System (ADS)

    Hu, Weida; Wan, Long; Liu, Xiaopan; Li, Qiang; Wang, Zhiqi

    2011-04-01

    The diamond abrasive particles were coated with the TiO2/Al2O3 film by the sol-gel technique. Compared with the uncoated diamonds, the TiO2/Al2O3 film was excellent material for the protection of the diamonds. The results showed that the incipient oxidation temperature of the TiO2/Al2O3 film coated diamonds in air atmosphere was 775 °C, which was higher 175 °C than that of the uncoated diamonds. And the coated diamonds also had better the diamond's single particle compressive strength and the impact toughness than that of uncoated diamonds after sintering at 750 °C. For the vitrified bond grinding wheels, replacing the uncoated diamonds with the TiO2/Al2O3 film coated diamonds, the volume expansion of the grinding wheels decreased from 6.2% to 3.4%, the porosity decreased from 35.7% to 25.7%, the hardness increased from 61.2HRC to 66.5HRC and the grinding ratio of the vitrified bond grinding wheels to carbide alloy (YG8) increased from 11.5 to 19.1.

  15. Impact resistance and energies of intermetallic bonded diamond composites and polycrystalline diamond compacts and their comparison

    NASA Astrophysics Data System (ADS)

    Gorla, Sai Prasanth

    Chemistry of intermetallic bonded diamond is studied. The impact resistance and energies of intermetallic bonded diamond is compared to current poly crystalline diamond compacts. IBD's are found to have high standards of hardness and have more impact energies absorbed. Intermetallic bonded diamond composite comprises of diamond particles dispersed in Tungsten carbide using Nickel aluminide (Ni3Al) as binder. In previous research conducted on IBD's, diamonds are successfully dispersed in intermetallic alloy of nickel aluminide and processed at 1350°C such that diamond particles remain intact without forming graphite. Composites are formed by milling, pressing the intermetallic binder and diamond particles and sintering at high temperature conditions.

  16. Optical field enhancement of nanometer-sized gaps at near-infrared frequencies.

    PubMed

    Ahn, Jae Sung; Kang, Taehee; Singh, Dilip K; Bahk, Young-Mi; Lee, Hyunhwa; Choi, Soo Bong; Kim, Dai-Sik

    2015-02-23

    We report near-field and far-field measurements of transmission through nanometer-sized gaps at near-infrared frequencies with varying the gap size from 1 nm to 10 nm. In the far-field measurements, we excluded direct transmission on the metal film surface via interferometric method. Kirchhoff integral formalism was used to relate the far-field intensity to the electric field at the nanogaps. In near-field measurements, field enhancement factors of the nanogaps were quantified by measuring transmission of the nanogaps using near-field scanning optical microscopy. All the measurements produce similar field enhancements of about ten, which we put in the context of comparing with the giant field enhancements in the terahertz regime.

  17. Extinction spectra of suspensions of microspheres: determination of the spectral refractive index and particle size distribution with nanometer accuracy.

    PubMed

    Gienger, Jonas; Bär, Markus; Neukammer, Jörg

    2018-01-10

    A method is presented to infer simultaneously the wavelength-dependent real refractive index (RI) of the material of microspheres and their size distribution from extinction measurements of particle suspensions. To derive the averaged spectral optical extinction cross section of the microspheres from such ensemble measurements, we determined the particle concentration by flow cytometry to an accuracy of typically 2% and adjusted the particle concentration to ensure that perturbations due to multiple scattering are negligible. For analysis of the extinction spectra, we employ Mie theory, a series-expansion representation of the refractive index and nonlinear numerical optimization. In contrast to other approaches, our method offers the advantage to simultaneously determine size, size distribution, and spectral refractive index of ensembles of microparticles including uncertainty estimation.

  18. Reproducible Crystallite Size of Mono-Dispersed and Scalable Biologically Produced Metal-Substituted Nanometer-Sized Magnetites

    NASA Astrophysics Data System (ADS)

    Moon, J.; Rawn, C.; Rondinone, A.; Love, L.; Roh, Y.; Lauf, R.; Phelps, T.

    2008-12-01

    Our previous research demonstrated that biosynthesized magnetite (biomagnetite) exhibited similar properties as chemically synthesized magnetite. To complement uses of the traditional chemically synthesized magnetite (chem-magnetite) biomagnetite must be exhibit highly reproducible sizes and be available in scalable qualities. Here we emphasize potentially advantageous properties of biomagnetite regarding size, reproducibility and scaling availability. Average crystallite size (ACS) of biomagnetites ranging from 10-100 nm was determined after varied 1) incubation times, 2) substitution of metal and lanthanide species, 3) degrees of congruent incorporation or retardation of substitution elements, 4) bacterial species with their varied ability to substitute elemental species, and 6) incubation temperature that can influence coalescence. The microbial production of biomagnetite has demonstrated capacity to make highly crystalline nanoscale particles of metal-substituted ferrites including compounds of Co, Ni, Cr, Mn, Zn and the rare earths in large quantity. Selected Zn-substituted magnetite (nominal composition of Zn0.6Fe2.4O4) has been recovered at over 1 kg (wet weight) in batches from 30 L fermentations. The massively produced extracellular magnetites were confirmed to exhibit good mono- dispersity via transmission electron microscopy (TEM). TEM also validated highly reproducible ACS of 13.1±0.8 nm size as determined through X-ray diffraction (N=7) at a 99 % confidence level. Based on the scale-up experiments performed using the 35 L reactor, the reduction in ACS variability and shorted incubation times of several days may be attributed to increases of electron donor input, and availability of divalent ions of the substitution metal with less ferrous ions in the case of doped magnetite, or a combination of the above. While costs of commercial nanometer sized magnetite (25-50 nm) may vary from 500/kg to > 1,000/kg, microbial mass production is likely capable of

  19. Artificial submicron or nanometer speckle fabricating technique and electron microscope speckle photography

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

    Liu Zhanwei; Xie Huimin; Fang Daining

    2007-03-15

    In this article, a novel artificial submicro- or nanometer speckle fabricating technique is proposed by taking advantage of submicro or nanometer particles. In the technique, submicron or nanometer particles were adhered to an object surface by using ultrasonic dispersing technique. The particles on the object surface can be regarded as submicro or nanometer speckle by using a scanning electronic microscope at a special magnification. In addition, an electron microscope speckle photography (EMSP) method is developed to measure in-plane submicron or nanometer deformation of the object coated with the artificial submicro or nanometer speckles. The principle of artificial submicro or nanometermore » speckle fabricating technique and the EMSP method are discussed in detail in this article. Some typical applications of this method are offered. The experimental results verified that the artificial submicro or nanometer speckle fabricating technique and EMSP method is feasible.« less

  20. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, J.E.; Kelly, T.F.

    1999-06-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains. 20 figs.

  1. Strengthening of metallic alloys with nanometer-size oxide dispersions

    DOEpatents

    Flinn, John E.; Kelly, Thomas F.

    1999-01-01

    Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

  2. In vitro studies on the effect of particle size on macrophage responses to nanodiamond wear debris

    PubMed Central

    Thomas, Vinoy; Halloran, Brian A.; Ambalavanan, Namasivayam; Catledge, Shane A.; Vohra, Yogesh K.

    2012-01-01

    Nanostructured diamond coatings improve the smoothness and wear characteristics of the metallic component of total hip replacements and increase the longevity of these implants, but the effect of nanodiamond wear debris on macrophages needs to be determined to estimate the long-term inflammatory effects of wear debris. The objective was to investigate the effect of the size of synthetic nanodiamond particles on macrophage proliferation (BrdU incorporation), apoptosis (Annexin-V flow cytometry), metabolic activity (WST-1 assay) and inflammatory cytokine production (qPCR). RAW 264.7 macrophages were exposed to varying sizes (6, 60, 100, 250 and 500 nm) and concentrations (0, 10, 50, 100 and 200 μg ml−1) of synthetic nanodiamonds. We observed that cell proliferation but not metabolic activity was decreased with nanoparticle sizes of 6–100 nm at lower concentrations (50 μg ml−1), and both cell proliferation and metabolic activity were significantly reduced with nanodiamond concentrations of 200 μg ml−1. Flow cytometry indicated a significant reduction in cell viability due to necrosis irrespective of particle size. Nanodiamond exposure significantly reduced gene expression of tumor necrosis factor-α, interleukin-1β, chemokine Ccl2 and platelet-derived growth factor compared to serum-only controls or titanium oxide (anatase 8 nm) nanoparticles, with variable effects on chemokine Cxcl2 and vascular endothelial growth factor. In general, our study demonstrates a size and concentration dependence of macrophage responses in vitro to nanodiamond particles as possible wear debris from diamond-coated orthopedic joint implants. PMID:22342422

  3. Formation of nanometer-size wires using infiltration into latent nuclear tracks

    DOEpatents

    Musket, Ronald G.; Felter, Thomas E.

    2002-01-01

    Nanometer-size wires having a cross-sectional dimension of less than 8 nm with controllable lengths and diameters are produced by infiltrating latent nuclear or ion tracks formed in trackable materials with atomic species. The trackable materials and atomic species are essentially insoluble in each other, thus the wires are formed by thermally driven, self-assembly of the atomic species during annealing, or re-crystallization, of the damage in the latent tracks. Unlike conventional ion track lithography, the inventive method does not require etching of the latent tracks.

  4. Nanometer-sized materials for solid-phase extraction of trace elements.

    PubMed

    Hu, Bin; He, Man; Chen, Beibei

    2015-04-01

    This review presents a comprehensive update on the state-of-the-art of nanometer-sized materials in solid-phase extraction (SPE) of trace elements followed by atomic-spectrometry detection. Zero-dimensional nanomaterials (fullerene), one-dimensional nanomaterials (carbon nanotubes, inorganic nanotubes, and nanowires), two-dimensional nanomaterials (nanofibers), and three-dimensional nanomaterials (nanoparticles, mesoporous nanoparticles, magnetic nanoparticles, and dendrimers) for SPE are discussed, with their application for trace-element analysis and their speciation in different matrices. A variety of other novel SPE sorbents, including restricted-access sorbents, ion-imprinted polymers, and metal-organic frameworks, are also discussed, although their applications in trace-element analysis are relatively scarce so far.

  5. Multicenter evaluation of a synthetic single-crystal diamond detector for CyberKnife small field size output factors.

    PubMed

    Russo, Serenella; Masi, Laura; Francescon, Paolo; Frassanito, Maria Cristina; Fumagalli, Maria Luisa; Marinelli, Marco; Falco, Maria Daniela; Martinotti, Anna Stefania; Pimpinella, Maria; Reggiori, Giacomo; Verona Rinati, Gianluca; Vigorito, Sabrina; Mancosu, Pietro

    2016-04-01

    The aim of the present work was to evaluate small field size output factors (OFs) using the latest diamond detector commercially available, PTW-60019 microDiamond, over different CyberKnife systems. OFs were measured also by silicon detectors routinely used by each center, considered as reference. Five Italian CyberKnife centers performed OFs measurements for field sizes ranging from 5 to 60mm, defined by fixed circular collimators (5 centers) and by Iris(™) variable aperture collimator (4 centers). Setup conditions were: 80cm source to detector distance, and 1.5cm depth in water. To speed up measurements two diamond detectors were used and their equivalence was evaluated. MonteCarlo (MC) correction factors for silicon detectors were used for comparing the OF measurements. Considering OFs values averaged over all centers, diamond data resulted lower than uncorrected silicon diode ones. The agreement between diamond and MC corrected silicon values was within 0.6% for all fixed circular collimators. Relative differences between microDiamond and MC corrected silicon diodes data for Iris(™) collimator were lower than 1.0% for all apertures in the totality of centers. The two microDiamond detectors showed similar characteristics, in agreement with the technical specifications. Excellent agreement between microDiamond and MC corrected silicon diode detectors OFs was obtained for both collimation systems fixed cones and Iris(™), demonstrating the microDiamond could be a suitable detector for CyberKnife commissioning and routine checks. These results obtained in five centers suggest that for CyberKnife systems microDiamond can be used without corrections even at the smallest field size. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  6. Nanometer-sized ceria-coated silica-iron oxide for the reagentless microextraction/preconcentration of heavy metals in environmental and biological samples followed by slurry introduction to ICP-OES.

    PubMed

    Dados, A; Paparizou, E; Eleftheriou, P; Papastephanou, C; Stalikas, C D

    2014-04-01

    A slurry suspension sampling technique is developed and optimized for the rapid microextraction of heavy metals and analysis using nanometer-sized ceria-coated silica-iron oxide particles and inductively coupled plasma optical emission spectrometry (ICP-OES). Magnetic-silica material is synthesized by a co-precipitation and sol-gel method followed by ceria coating through a precipitation. The large particles are removed using a sedimentation-fractionation procedure and a magnetic homogeneous colloidal suspension of ceria-modified iron oxide-silica is produced for microextraction. The nanometer-sized particles are separated from the sample solution magnetically and analyzed with ICP-OES using a slurry suspension sampling approach. The ceria-modified iron oxide-silica does not contain any organic matter and this probably justifies the absence of matrix effect on plasma atomization capacity, when increased concentrations of slurries are aspirated. The As, Be, Mo, Cr, Cu, Pb, Hg, Sb, Se and V can be preconcentrated by the proposed method at pH 6.0 while Mn, Cd, Co and Ni require a pH ≥ 8.0. Satisfactory values are obtained for the relative standard deviations (2-6%), recoveries (88-102%), enrichment factors (14-19) and regression correlation coefficients as well as detectability, at sub-μg L(-1) levels. The applicability of magnetic ceria for the microextraction of metal ions in combination with the slurry introduction technique using ICP is substantiated by the analysis of environmental water and urine samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Interfacial characteristics of diamond/aluminum composites with high thermal conductivity fabricated by squeeze-casting method

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

    Jiang, Longtao, E-mail: longtaojiang@163.com; Wang, Pingping; Xiu, Ziyang

    2015-08-15

    In this work, aluminum matrix composites reinforced with diamond particles (diamond/aluminum composites) were fabricated by squeeze casting method. The material exhibited a thermal conductivity as high as 613 W / (m · K). The obtained composites were investigated by scanning electron microscope and transmission electron microscope in terms of the (100) and (111) facets of diamond particles. The diamond particles were observed to be homogeneously distributed in the aluminum matrix. The diamond{sub (111)}/Al interface was found to be devoid of reaction products. While at the diamond{sub (100)}/Al interface, large-sized aluminum carbides (Al{sub 4}C{sub 3}) with twin-crystal structure were identified. Themore » interfacial characteristics were believed to be responsible for the excellent thermal conductivity of the material. - Graphical abstract: Display Omitted - Highlights: • Squeeze casting method was introduced to fabricate diamond/Al composite. • Sound interfacial bonding with excellent thermal conductivity was produced. • Diamond{sub (111)}/ aluminum interface was firstly characterized by TEM/HRTEM. • Physical combination was the controlling bonding for diamond{sub (111)}/aluminum. • The growth mechanism of Al{sub 4}C{sub 3} was analyzed by crystallography theory.« less

  8. Adsorptive Separation and Sequestration of Krypton, I and C14 on Diamond Nanoparticles

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

    Ghosh, Tushar; Loyalka, Sudarsha; Prelas, Mark

    The objective of this research proposal was to address the separation and sequestration of Kr and I from each other using nano-sized diamond particles and retaining these in diamond until they decay to the background level or can be used as a byproduct. Following removal of Kr and I, an adsorbent will be used to adsorb and store CO2 from the CO2 rich stream. A Field Enhanced Diffusion with Optical Activation (FEDOA-a large scale process that takes advantage of thermal, electrical, and optical activation to enhance the diffusion of an element into diamond structure) was used to load Kr andmore » I on micron or nano sized particles having a larger relative surface area. The diamond particles can be further increased by doping it with boron followed by irradiation in a neutron flux. Previous studies showed that the hydrogen storage capacity could be increased significantly by using boron-doped irradiated diamond particles. Diamond powders were irradiated for a longer time by placing them in a quartz tube. The surface area was measured using a Quantachrome Autosorb system. No significant increase in the surface area was observed. Total surface area was about 1.7 m2/g. This suggests the existence of very minimal pores. Interestingly it showed hysteresis upon desorption. A reason for this may be strong interaction between the surface and the nitrogen molecules. Adsorption runs at higher temperatures did not show any adsorption of krypton on diamond. Use of a GC with HID detector to determine the adsorption capacity from the breakthrough curves was attempted, but experimental difficulties were encountered.« less

  9. Nanometal particle reagents for sensitive, MEMS based fiber-optic, multi-analyte, immuno-biosensing

    NASA Astrophysics Data System (ADS)

    Hong, Bin

    Integration of nanotechnology to medical diagnostics has brought a new era to public health practice. An excellent example is the utilization of unique optoelectronic properties of nanoparticles to develop highly sensitive biosensing devices for point-of-care (POC) disease diagnosis/prognosis. Fluorophore mediated, immuno-biosensors are important disease detection tools. The property of intra-molecular fluorescence quenching of most fluorophores, however, limits the sensitivity of this type of sensors. A plasmon-rich nanometal particle (NMP) can transfer the lone pair electrons of a fluorophore, which normally participate in the fluorescence self-quenching, to its surface plasmon field, resulting in artificial fluorescence enhancement. The enhancement was found to depend on the metal type, the particle size, the distance between a particle and a fluorophore, and the quantum yield of a fluorophore. Some biocompatible solvents were also found to increase the fluorescence emission efficiency via effective dipole coupling between the fluorophore and the solvent molecule. The application of solvents in inmuno-sensing could additionally improve the fluorescence light retrieval by the conformational change of the protein complexes in solvent. The mixture of the NMP and the solvent, which we defined as nanometal particle reagent (NMPR), provided even higher enhancements. Cardiovascular diseases (CVDs) kill 1 person in every 6 seconds. Among the CVDs, acute myocardial infarction (AMI; commonly known as heart attack) is the most dangerous and time-sensitive killer. A rapid and accurate AMI diagnosis is crucial for saving many lives. For this purpose, a fluorophore mediated, immuno-reaction based, multi-cardiac-marker sensing device was developed, to quantify four myocardium-specific proteins simultaneously, accurately, rapidly, and user-friendly. The four cardiac markers of our choice were myoglobin (MG), C-reactive protein (CRP), cardiac troponin I (cTnI), and B

  10. Wollastonite Carbonation in Water-Bearing Supercritical CO2: Effects of Particle Size.

    PubMed

    Min, Yujia; Li, Qingyun; Voltolini, Marco; Kneafsey, Timothy; Jun, Young-Shin

    2017-11-07

    The performance of geologic CO 2 sequestration (GCS) can be affected by CO 2 mineralization and changes in the permeability of geologic formations resulting from interactions between water-bearing supercritical CO 2 (scCO 2 ) and silicates in reservoir rocks. However, without an understanding of the size effects, the findings in previous studies using nanometer- or micrometer-size particles cannot be applied to the bulk rock in field sites. In this study, we report the effects of particle sizes on the carbonation of wollastonite (CaSiO 3 ) at 60 °C and 100 bar in water-bearing scCO 2 . After normalization by the surface area, the thickness of the reacted wollastonite layer on the surfaces was independent of particle sizes. After 20 h, the reaction was not controlled by the kinetics of surface reactions but by the diffusion of water-bearing scCO 2 across the product layer on wollastonite surfaces. Among the products of reaction, amorphous silica, rather than calcite, covered the wollastonite surface and acted as a diffusion barrier to water-bearing scCO 2 . The product layer was not highly porous, with a specific surface area 10 times smaller than that of the altered amorphous silica formed at the wollastonite surface in aqueous solution. These findings can help us evaluate the impacts of mineral carbonation in water-bearing scCO 2 .

  11. Liquid impact and fracture of free-standing CVD diamond

    NASA Astrophysics Data System (ADS)

    Kennedy, Claire F.; Telling, Robert H.; Field, John E.

    1999-07-01

    The Cavendish Laboratory has developed extensive facilities for studies of liquid and solid particle erosion. This paper describes the high-speed liquid impact erosion of thin CVD diamond discs and the variation with grain sizes of the absolute damage threshold velocity (ADTV), viz., the threshold below which the specimen shows no damage. All specimens fail by rear surface cracking and there is shown to be a shallow dependence of rear surface ADTV on grain size. Fracture propagation in CVD diamond has also been monitored using a specially-designed double-torsion apparatus and data for K1C are presented. Tentatively, the results suggest that finer-grained CVD diamond exhibits a higher fracture toughness, although the differences are slight even over a fourfold variation in the mean grain size. No preference for intergranular fracture was observed and one may conclude from this that the grain boundaries themselves do not seriously weaken the material. The large pre-existing flaws, both within and between grains, whose size varies the grain size are believed to be the dominant source of weakness.

  12. Levitation and collection of diamond fine particles in the rf plasma chamber equipped with a hot filament

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

    Shimizu, S.; Shimizu, T.; Thomas, H. M.

    2011-11-15

    We demonstrate the levitation of diamond fine particles in a H{sub 2} rf plasma chamber equipped with a hot filament and heated electrodes. The levitation conditions should be carefully chosen to compensate the strong thermophoretic forces caused by the filament and the electrodes. This levitation technique with the existence of a hot filament can be applied, e.g., for the efficient growth of diamond layers on seed particles injected and levitated in an rf plasma with reactive gases, e.g., CH{sub 4}/H{sub 2}. Additionally, the method for direct capture of levitated particles on a planar substrate was established, which is useful ifmore » it is necessary to analyze the particles after the levitation.« less

  13. Sensitive SERS detection at the single-particle level based on nanometer-separated mushroom-shaped plasmonic dimers

    NASA Astrophysics Data System (ADS)

    Xiang, Quan; Li, Zhiqin; Zheng, Mengjie; Liu, Qing; Chen, Yiqin; Yang, Lan; Jiang, Tian; Duan, Huigao

    2018-03-01

    Elevated metallic nanostructures with nanogaps (<10 nm) possess advantages for surface enhanced Raman scattering (SERS) via the synergic effects of nanogaps and efficient decoupling from the substrate through an elevated three-dimensional (3D) design. In this work, we demonstrate a pattern-transfer-free process to reliably define elevated nanometer-separated mushroom-shaped dimers directly from 3D resist patterns based on the gap-narrowing effect during the metallic film deposition. By controlling the initial size of nanogaps in resist structures and the following deposited film thickness, metallic nanogaps could be tuned at the sub-10 nm scale with single-digit nanometer precision. Both experimental and simulated results revealed that gold dimer on mushroom-shaped pillars have the capability to achieve higher SERS enhancement factor comparing to those plasmonic dimers on cylindrical pillars or on a common SiO2/Si substrate, implying that the nanometer-gapped elevated dimer is an ideal platform to achieve the highest possible field enhancement for various plasmonic applications.

  14. Mutations in signal recognition particle SRP54 cause syndromic neutropenia with Shwachman-Diamond-like features.

    PubMed

    Carapito, Raphael; Konantz, Martina; Paillard, Catherine; Miao, Zhichao; Pichot, Angélique; Leduc, Magalie S; Yang, Yaping; Bergstrom, Katie L; Mahoney, Donald H; Shardy, Deborah L; Alsaleh, Ghada; Naegely, Lydie; Kolmer, Aline; Paul, Nicodème; Hanauer, Antoine; Rolli, Véronique; Müller, Joëlle S; Alghisi, Elisa; Sauteur, Loïc; Macquin, Cécile; Morlon, Aurore; Sancho, Consuelo Sebastia; Amati-Bonneau, Patrizia; Procaccio, Vincent; Mosca-Boidron, Anne-Laure; Marle, Nathalie; Osmani, Naël; Lefebvre, Olivier; Goetz, Jacky G; Unal, Sule; Akarsu, Nurten A; Radosavljevic, Mirjana; Chenard, Marie-Pierre; Rialland, Fanny; Grain, Audrey; Béné, Marie-Christine; Eveillard, Marion; Vincent, Marie; Guy, Julien; Faivre, Laurence; Thauvin-Robinet, Christel; Thevenon, Julien; Myers, Kasiani; Fleming, Mark D; Shimamura, Akiko; Bottollier-Lemallaz, Elodie; Westhof, Eric; Lengerke, Claudia; Isidor, Bertrand; Bahram, Seiamak

    2017-11-01

    Shwachman-Diamond syndrome (SDS) (OMIM #260400) is a rare inherited bone marrow failure syndrome (IBMFS) that is primarily characterized by neutropenia and exocrine pancreatic insufficiency. Seventy-five to ninety percent of patients have compound heterozygous loss-of-function mutations in the Shwachman-Bodian-Diamond syndrome (sbds) gene. Using trio whole-exome sequencing (WES) in an sbds-negative SDS family and candidate gene sequencing in additional SBDS-negative SDS cases or molecularly undiagnosed IBMFS cases, we identified 3 independent patients, each of whom carried a de novo missense variant in srp54 (encoding signal recognition particle 54 kDa). These 3 patients shared congenital neutropenia linked with various other SDS phenotypes. 3D protein modeling revealed that the 3 variants affect highly conserved amino acids within the GTPase domain of the protein that are critical for GTP and receptor binding. Indeed, we observed that the GTPase activity of the mutated proteins was impaired. The level of SRP54 mRNA in the bone marrow was 3.6-fold lower in patients with SRP54-mutations than in healthy controls. Profound reductions in neutrophil counts and chemotaxis as well as a diminished exocrine pancreas size in a SRP54-knockdown zebrafish model faithfully recapitulated the human phenotype. In conclusion, autosomal dominant mutations in SRP54, a key member of the cotranslation protein-targeting pathway, lead to syndromic neutropenia with a Shwachman-Diamond-like phenotype.

  15. Nano-inclusions in diamond: Evidence of diamond genesis

    NASA Astrophysics Data System (ADS)

    Wirth, R.

    2015-12-01

    The use of Focused Ion Beam technology (FIB) for TEM sample preparation introduced approximately 15 years ago revolutionized the application of TEM in Geosciences. For the first time, FIB enabled cutting samples for TEM use from exactly the location we are interested in. Applied to diamond investigation, this technique revealed the presence of nanometre-sized inclusions in diamond that have been simply unknown before. Nanoinclusions in diamond from different location and origin such as diamonds from the Lower and Upper Mantle, metamorphic diamonds (Kazakhstan, Erzgebirge, Bohemia), diamonds from ophiolites (Tibet, Mongolia, Xinjiang, Ural Mountains), diamonds from igneous rocks (Hawaii, Kamchatka) and impact diamonds (Popigai Crater, Siberia) have been investigated during the last 15 years. The major conclusion of all these TEM studies is, that the nanoinclusions, their phases and phase composition together with the micro- and nanostructure evidence the origin of diamond and genesis of diamond. We can discriminate Five different mechanisms of diamond genesis in nature are observed: Diamond crystallized from a high-density fluid (Upper mantle and metamorphic diamond). Diamond crystallized from carbonatitic melt (Lower mantle diamond). Diamond precipitates from a metal alloy melt (Diamond from ophiolites). Diamond crystallized by gas phase condensation or chemical vapour condensation (CVD) (Lavas from Kamchatka, xenoliths in Hawaiian lavas). Direct transformation of graphite into diamond.

  16. Novel polymer composite having diamond particles and boron nitride platelets for thermal management of electric vehicle motors

    NASA Astrophysics Data System (ADS)

    Nakajima, Anri; Shoji, Atsushi; Yonemori, Kei; Seo, Nobuhide

    2016-02-01

    Thermal conductivities of silicone matrix polymers including fillers of diamond particles and/or hexagonal boron nitride (h-BN) platelets were systematically investigated in an attempt to find a thermal interface material (TIM) having high isotropic thermal conductivity and high electrical insulating ability to enable efficient heat dissipation from the motor coil ends of electric vehicles. The TIM with mixed fillers of diamond particles and h-BN platelets had a maximum thermal conductivity of 6.1 W m-1 K-1 that was almost isotropic. This is the highest value among the thermal conductivities of TIMs with silicone matrix polymer reported to date. The mechanism behind the thermal conductivity of the TIMs was also examined from the viewpoint of the change in the number of thermally conductive networks and/or a decrease in the thermal resistivity of junctions of neighboring diamond particles through the incorporation of h-BN platelets. The TIMs developed in this study will make it possible to manage the heat of electric motors and will help to popularize electric vehicles.

  17. Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

    PubMed

    Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

    2006-03-15

    We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) < 1.0 nm) than those of other etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

  18. Population characteristics of submicrometer-sized craters on regolith particles from asteroid Itokawa

    NASA Astrophysics Data System (ADS)

    Matsumoto, Toru; Hasegawa, S.; Nakao, S.; Sakai, M.; Yurimoto, H.

    2018-03-01

    We investigated impact crater structures on regolith particles from asteroid Itokawa using scanning electron microscopy. We observed the surfaces of 51 Itokawa particles, ranging from 15 μm to 240 μm in size. Craters with average diameters ranging from 10 nm to 2.8 μm were identified on 13 Itokawa particles larger than 80 μm. We examined the abundance, spatial distribution, and morphology of approximately 900 craters on six Itokawa particles. Craters with sizes in excess of 200 nm are widely dispersed, with spatial densities from 2.6 μm2 to 4.5 μm2; a fraction of the craters was locally concentrated with a density of 0.1 μm2. The fractal dimension of the cumulative crater diameters ranges from 1.3 to 2.3. Craters of several tens of nanometers in diameter exhibit pit and surrounding rim structures. Craters of more than 100 nm in diameter commonly have melted residue at their bottom. These morphologies are similar to those of submicrometer-sized craters on lunar regolith. We estimated the impactor flux on Itokawa regolith-forming craters, assuming that the craters were accumulated during direct exposure to the space environment for 102 to 104 yr. The range of impactor flux onto Itokawa particles is estimated to be at least one order of magnitude higher than the interplanetary dust flux and comparable to the secondary impact flux on the Moon. This indicates that secondary ejecta impacts are probably the dominant cratering process in the submicrometer range on Itokawa regolith particles, as well as on the lunar surface. We demonstrate that secondary submicrometer craters can be produced anywhere in centimeter- to meter-sized depressions on Itokawa's surface through primary interplanetary dust impacts. If the surface unevenness on centimeter to meter scales is a significant factor determining the abundance of submicrometer secondary cratering, the secondary impact flux could be independent of the overall shapes or sizes of celestial bodies, and the secondary

  19. Electrically conductive diamond electrodes

    DOEpatents

    Swain, Greg [East Lansing, MI; Fischer, Anne [Arlington, VA; Bennett, Jason [Lansing, MI; Lowe, Michael [Holt, MI

    2009-05-19

    An electrically conductive diamond electrode and process for preparation thereof is described. The electrode comprises diamond particles coated with electrically conductive doped diamond preferably by chemical vapor deposition which are held together with a binder. The electrodes are useful for oxidation reduction in gas, such as hydrogen generation by electrolysis.

  20. Nanometer-scale anatomy of entire Stardust tracks

    NASA Astrophysics Data System (ADS)

    Nakamura-Messenger, Keiko; Keller, Lindsay P.; Clemett, Simon J.; Messenger, Scott; Ito, Motoo

    2011-07-01

    We have developed new sample preparation and analytical techniques tailored for entire aerogel tracks of Wild 2 sample analyses both on "carrot" and "bulbous" tracks. We have successfully ultramicrotomed an entire track along its axis while preserving its original shape. This innovation allowed us to examine the distribution of fragments along the entire track from the entrance hole all the way to the terminal particle. The crystalline silicates we measured have Mg-rich compositions and O isotopic compositions in the range of meteoritic materials, implying that they originated in the inner solar system. The terminal particle of the carrot track is a 16O-rich forsteritic grain that may have formed in a similar environment as Ca-, Al-rich inclusions and amoeboid olivine aggregates in primitive carbonaceous chondrites. The track also contains submicron-sized diamond grains likely formed in the solar system. Complex aromatic hydrocarbons distributed along aerogel tracks and in terminal particles. These organics are likely cometary but affected by shock heating.

  1. Estimates of the Size Distribution of Meteoric Smoke Particles From Rocket-Borne Impact Probes

    NASA Astrophysics Data System (ADS)

    Antonsen, Tarjei; Havnes, Ove; Mann, Ingrid

    2017-11-01

    Ice particles populating noctilucent clouds and being responsible for polar mesospheric summer echoes exist around the mesopause in the altitude range from 80 to 90 km during polar summer. The particles are observed when temperatures around the mesopause reach a minimum, and it is presumed that they consist of water ice with inclusions of smaller mesospheric smoke particles (MSPs). This work provides estimates of the mean size distribution of MSPs through analysis of collision fragments of the ice particles populating the mesospheric dust layers. We have analyzed data from two triplets of mechanically identical rocket probes, MUltiple Dust Detector (MUDD), which are Faraday bucket detectors with impact grids that partly fragments incoming ice particles. The MUDD probes were launched from Andøya Space Center (69°17'N, 16°1'E) on two payloads during the MAXIDUSTY campaign on 30 June and 8 July 2016, respectively. Our analysis shows that it is unlikely that ice particles produce significant current to the detector, and that MSPs dominate the recorded current. The size distributions obtained from these currents, which reflect the MSP sizes, are described by inverse power laws with exponents of k˜ [3.3 ± 0.7, 3.7 ± 0.5] and k˜ [3.6 ± 0.8, 4.4 ± 0.3] for the respective flights. We derived two k values for each flight depending on whether the charging probability is proportional to area or volume of fragments. We also confirm that MSPs are probably abundant inside mesospheric ice particles larger than a few nanometers, and the volume filling factor can be a few percent for reasonable assumptions of particle properties.

  2. Effect of Biophysical Properties of Phosphatidylserine Particle on Immune Tolerance Induction Toward Factor VIII in a Hemophilia A Mouse Model.

    PubMed

    Ramakrishnan, Radha; Balu-Iyer, Sathy V

    2016-10-01

    A major complication in the replacement therapy of Factor VIII (FVIII) for Hemophilia A is the development of unwanted immune responses. Previous studies from our laboratory have shown that pretreatment of FVIII in the presence of phosphatidylserine (PS) resulted in hyporesponsiveness to subsequent administration of FVIII alone, due to the ability of PS to convert an immunogen to a tolerogen. We investigated the importance of biophysical properties of PS liposomes on its ability to convert an immunogen to a tolerogen. PS particles were prepared differing in size, protein-lipid topology, lamellarity, and % association to FVIII keeping the composition of the particle same. PS particles were prepared in 2 different sizes with differing biophysical properties: smaller particles in the nanometer range (200 nm) and larger size particles in the micron range (2 μm). Hemophilia A animals treated with both the nanometer and micron size PS particles showed a significant reduction in anti-FVIII antibody titers when compared to animals receiving free FVIII alone. Upon rechallenge with free FVIII animals that received FVIII along with the nanometer size particle continued to show reduced antibody responses. Animals receiving the micron size particle showed a slight increase in titers although they remained significantly lower than the free FVIII treated group. Upon culture with bone marrow derived dendritic cells, the nanometer size particle showed a reduction in CD40 expression and an increase in transforming growth factor-β cytokine production, which was not observed with the micron size particle. These results show that biophysical properties of PS play an important role in tolerance. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  3. Understanding the effect of size and shape of gold nanomaterials on nanometal surface energy transfer.

    PubMed

    Rakshit, Soumyadipta; Moulik, Satya Priya; Bhattacharya, Subhash Chandra

    2017-04-01

    Gold Nanomaterials (GNMs) interact with fluorophores via electromagnetic coupling under excitation. In this particular work we carried out (to the best of our knowledge for the first time) a comprehensive study of systematic quenching of a blue emitter 2-Anthracene Sulfonate (2-AS) in the presence of gold nanoparticles of different size and shape. We synthesized gold nanomaterials of four different dimensions [nanoparticle (0D), nanorod (1D), nanotriangle (2D) and nanobipyramids (3D)] and realized the underlying effect on the emitting dipole in terms of steady and time resolved fluorescence. Nanometal Surface Energy Transfer (NSET) has already been proved to be the best long range spectroscopic ruler so far. Many attempts have been made to understand the interaction between a fluorescent molecule and gold nanomaterials. But not a single model can interpret alone the interaction phenomena. We have opted three different models to compare the experimental and theoretical data. Due to the presence of size dependent absorptivity and dielectric function, modified CPS-Kuhn model was proved to be the worthiest to comprehend variance of behavior of an emitting dipole in close proximity to nanometal surface by coupling with the image dipole of gold nanomaterials. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Quantum decrease of capacitance in a nanometer-sized tunnel junction

    NASA Astrophysics Data System (ADS)

    Untiedt, C.; Saenz, G.; Olivera, B.; Corso, M.; Sabater, C.; Pascual, J. I.

    2013-03-01

    We have studied the capacitance of the tunnel junction defined by the tip and sample of a Scanning Tunnelling Microscope through the measurement of the electrostatic forces and impedance of the junction. A decrease of the capacitance when a tunnel current is present has shown to be a more general phenomenon as previously reported in other systems. On another hand, an unexpected reduction of the capacitance is also observed when increasing the applied voltage above the work function energy of the electrodes to the Field Emission (FE) regime, and the decrease of capacitance due to a single FE-Resonance has been characterized. All these effects should be considered when doing measurements of the electronic characteristics of nanometer-sized electronic devices and have been neglected up to date. Spanish government (FIS2010-21883-C02-01, CONSOLIDER CSD2007-0010), Comunidad Valenciana (ACOMP/2012/127 and PROMETEO/2012/011)

  5. Diamond Pixel Detectors

    NASA Astrophysics Data System (ADS)

    Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foster, J.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Gobbi, B.; Grim, G. P.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Lander, R.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Oh, A.; Pan, L. S.; Pernicka, M.; Perera, L.; Pirollo, S.; Plano, R.; Procario, M.; Riester, J. L.; Roe, S.; Rott, C.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Wedenig, R.; Weilhammer, P.; White, C.; Zeuner, W.; Zoeller, M.

    2001-06-01

    Diamond based pixel detectors are a promising radiation-hard technology for use at the LHC. We present first results on a CMS diamond pixel sensor. With a threshold setting of 2000 electrons, an average pixel efficiency of 78% was obtained for normally incident minimum ionizing particles.

  6. Colloidal crystals with diamond symmetry at optical lengthscales

    NASA Astrophysics Data System (ADS)

    Wang, Yifan; Jenkins, Ian C.; McGinley, James T.; Sinno, Talid; Crocker, John C.

    2017-02-01

    Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require--a regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals that contain a suitable diamond structure, using DNA to direct the self-assembly process. While diamond symmetry crystals have been grown from much smaller nanoparticles, none of those previous methods suffice for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light. Intriguingly, the crystals we observe do not readily form in previously validated simulations; nor have they been predicted theoretically. This finding suggests that other unexpected microstructures may be accessible using this approach and bodes well for future efforts to inexpensively mass-produce metamaterials for an array of photonic applications.

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

    PubMed

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

    2014-06-24

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

  8. Image processing enhancement of high-resolution TEM micrographs of nanometer-size metal particles

    NASA Technical Reports Server (NTRS)

    Artal, P.; Avalos-Borja, M.; Soria, F.; Poppa, H.; Heinemann, K.

    1989-01-01

    The high-resolution TEM detectability of lattice fringes from metal particles supported on substrates is impeded by the substrate itself. Single value decomposition (SVD) and Fourier filtering (FFT) methods were applied to standard high resolution micrographs to enhance lattice resolution from particles as well as from crystalline substrates. SVD produced good results for one direction of fringes, and it can be implemented as a real-time process. Fourier methods are independent of azimuthal directions and allow separation of particle lattice planes from those pertaining to the substrate, which makes it feasible to detect possible substrate distortions produced by the supported particle. This method, on the other hand, is more elaborate, requires more computer time than SVD and is, therefore, less likely to be used in real-time image processing applications.

  9. Effect of Diamond Bur Grit Size on Composite Repair.

    PubMed

    Valente, Lisia L; Silva, Manuela F; Fonseca, Andrea S; Münchow, Eliseu A; Isolan, Cristina P; Moraes, Rafael R

    2015-06-01

    This study investigated the effect of diamond bur grit size on the repair bond strength of fresh and aged resin composites. Blocks of microhybrid composite (Opallis, FGM) were stored in distilled water at 37°C for 24 h (fresh composite) or subjected to 5000 thermal cycles (aged composite). The surfaces were roughened using diamond-coated, flame-shaped carbide burs with medium grit (#3168), fine grit (#3168F), or extra-fine grit (#3168FF). The control group underwent no surface treatment. Surface roughness, water contact angle, and surface topography by scanning electron microscopy (SEM) were evaluated (n = 3). Samples were restored with resin composite and sectioned into beam-shaped specimens, which were subjected to microtensile bond testing. Failure modes were classified using a stereomicroscope. Data were statistically analyzed using the Student- Newman-Keuls test and two-way ANOVA, with significance set at p < 0.05. Higher surface roughness was observed for groups treated with the medium- and fine-grit burs; aged composites were rougher than fresh composites. The water contact angle formed on the aged composite was lower than that on the fresh composite. The highest repair bond strength was observed for the fine-grit bur group, and the lowest was recorded for control. Interfacial failures were more predominant. SEM images showed that the surfaces treated with fine- and extra-fine-grit burs had a more irregular topography. Surface roughening of fresh or aged resin composites with diamond burs improved retention of the repair material. Fine-grit burs generally performed better than medium- and extra-fine-grit burs.

  10. Nanometer scale thermometry in a living cell

    PubMed Central

    Kucsko, G.; Maurer, P. C.; Yao, N. Y.; Kubo, M.; Noh, H. J.; Lo, P. K.; Park, H.; Lukin, M. D.

    2014-01-01

    Sensitive probing of temperature variations on nanometer scales represents an outstanding challenge in many areas of modern science and technology1. In particular, a thermometer capable of sub-degree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool for many areas of biological, physical and chemical research; possibilities range from the temperature-induced control of gene expression2–5 and tumor metabolism6 to the cell-selective treatment of disease7,8 and the study of heat dissipation in integrated circuits1. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the sub-cellular level2–5. Here, we demonstrate a new approach to nanoscale thermometry that utilizes coherent manipulation of the electronic spin associated with nitrogen-vacancy (NV) color centers in diamond. We show the ability to detect temperature variations down to 1.8 mK (sensitivity of 9mK/Hz) in an ultra-pure bulk diamond sample. Using NV centers in diamond nanocrystals (nanodiamonds, NDs), we directly measure the local thermal environment at length scales down to 200 nm. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the sub-cellular level, enabling unique potential applications in life sciences. PMID:23903748

  11. Winding single-molecule double-stranded DNA on a nanometer-sized reel

    PubMed Central

    You, Huijuan; Iino, Ryota; Watanabe, Rikiya; Noji, Hiroyuki

    2012-01-01

    A molecular system of a nanometer-sized reel was developed from F1–ATPase, a rotary motor protein. By combination with magnetic tweezers and optical tweezers, single-molecule double-stranded DNA (dsDNA) was wound around the molecular reel. The bending stiffness of dsDNA was determined from the winding tension (0.9–6.0 pN) and the diameter of the wound loop (21.4–8.5 nm). Our results were in good agreement with the conventional worm-like chain model and a persistence length of 54 ± 9 nm was estimated. This molecular reel system offers a new platform for single-molecule study of micromechanics of sharply bent DNA molecules and is expected to be applicable to the elucidation of the molecular mechanism of DNA-associating proteins on sharply bent DNA strands. PMID:22772992

  12. Phase Retrieval System for Assessing Diamond Turning and Optical Surface Defects

    NASA Technical Reports Server (NTRS)

    Dean, Bruce; Maldonado, Alex; Bolcar, Matthew

    2011-01-01

    An optical design is presented for a measurement system used to assess the impact of surface errors originating from diamond turning artifacts. Diamond turning artifacts are common by-products of optical surface shaping using the diamond turning process (a diamond-tipped cutting tool used in a lathe configuration). Assessing and evaluating the errors imparted by diamond turning (including other surface errors attributed to optical manufacturing techniques) can be problematic and generally requires the use of an optical interferometer. Commercial interferometers can be expensive when compared to the simple optical setup developed here, which is used in combination with an image-based sensing technique (phase retrieval). Phase retrieval is a general term used in optics to describe the estimation of optical imperfections or aberrations. This turnkey system uses only image-based data and has minimal hardware requirements. The system is straightforward to set up, easy to align, and can provide nanometer accuracy on the measurement of optical surface defects.

  13. Microstructural Characterisation and Wear Behaviour of Diamond Composite Materials

    PubMed Central

    Boland, James N.; Li, Xing S.

    2010-01-01

    Since the initial research leading to the production of diamond composite materials, there have been several important developments leading to significant improvements in the properties of these superhard composite materials. Apart from the fact that diamonds, whether originating from natural resources or synthesised commercially, are the hardest and most wear-resistant materials commonly available, there are other mechanical properties that limit their industrial application. These include the low fracture toughness and low impact strength of diamond. By incorporating a range of binder phases into the sintering production process of these composites, these critically important properties have been radically improved. These new composites can withstand much higher operating temperatures without markedly reducing their strength and wear resistance. Further innovative steps are now being made to improve the properties of diamond composites by reducing grain and particle sizes into the nano range. This review will cover recent developments in diamond composite materials with special emphasis on microstructural characterisation. The results of such studies should assist in the design of new, innovative diamond tools as well as leading to radical improvements in the productivity of cutting, drilling and sawing operations in the exploration, mining, civil construction and manufacturing industries.

  14. Graphene nanoribbon field effect transistor for nanometer-size on-chip temperature sensor

    NASA Astrophysics Data System (ADS)

    Banadaki, Yaser M.; Srivastava, Ashok; Sharifi, Safura

    2016-04-01

    Graphene has been extensively investigated as a promising material for various types of high performance sensors due to its large surface-to-volume ratio, remarkably high carrier mobility, high carrier density, high thermal conductivity, extremely high mechanical strength and high signal-to-noise ratio. The power density and the corresponding die temperature can be tremendously high in scaled emerging technology designs, urging the on-chip sensing and controlling of the generated heat in nanometer dimensions. In this paper, we have explored the feasibility of a thin oxide graphene nanoribbon (GNR) as nanometer-size temperature sensor for detecting local on-chip temperature at scaled bias voltages of emerging technology. We have introduced an analytical model for GNR FET for 22nm technology node, which incorporates both thermionic emission of high-energy carriers and band-to-band-tunneling (BTBT) of carriers from drain to channel regions together with different scattering mechanisms due to intrinsic acoustic phonons and optical phonons and line-edge roughness in narrow GNRs. The temperature coefficient of resistivity (TCR) of GNR FET-based temperature sensor shows approximately an order of magnitude higher TCR than large-area graphene FET temperature sensor by accurately choosing of GNR width and bias condition for a temperature set point. At gate bias VGS = 0.55 V, TCR maximizes at room temperature to 2.1×10-2 /K, which is also independent of GNR width, allowing the design of width-free GNR FET for room temperature sensing applications.

  15. Size and Shape of Protein Molecules at the Nanometer Level Determined by Sedimentation, Gel Filtration, and Electron Microscopy

    PubMed Central

    2009-01-01

    An important part of characterizing any protein molecule is to determine its size and shape. Sedimentation and gel filtration are hydrodynamic techniques that can be used for this medium resolution structural analysis. This review collects a number of simple calculations that are useful for thinking about protein structure at the nanometer level. Readers are reminded that the Perrin equation is generally not a valid approach to determine the shape of proteins. Instead, a simple guideline is presented, based on the measured sedimentation coefficient and a calculated maximum S, to estimate if a protein is globular or elongated. It is recalled that a gel filtration column fractionates proteins on the basis of their Stokes radius, not molecular weight. The molecular weight can be determined by combining gradient sedimentation and gel filtration, techniques available in most biochemistry laboratories, as originally proposed by Siegel and Monte. Finally, rotary shadowing and negative stain electron microscopy are powerful techniques for resolving the size and shape of single protein molecules and complexes at the nanometer level. A combination of hydrodynamics and electron microscopy is especially powerful. PMID:19495910

  16. Diamond at the nanoscale: applications of diamond nanoparticles from cellular biomarkers to quantum computing.

    PubMed

    Holt, Katherine B

    2007-12-15

    Although nanocrystalline diamond powders have been produced in industrial quantities, mainly by detonation synthesis, for many decades their use in applications other than traditional polishing and grinding have been limited, until recently. This paper presents the wide-ranging applications of nanodiamond particles to date and discusses future research directions in this field. Owing to the recent commercial availability of these powders and the present interest in nanotechnology, one can predict a huge increase in research with these materials in the very near future. However, to fully exploit these materials, fundamental as well as applied research is required to understand the transition between bulk and surface properties as the size of particles decreases.

  17. Understanding batteries on the micro- and nanometer scale

    ScienceCinema

    None

    2018-01-16

    In order to understand performance limitations and failure mechanisms of batteries, one has to investigate processes on the micro- and nanometer scale. A typical failure mechanism in lithium metal batteries is dendritic growth. During discharge, lithium is stripped of the anode surface and migrates to the cathode. During charge, lithium is deposited back on the anode. Repeated cycling can result in stripping and re-deposition that roughens the surface. The roughening of the surface changes the electric field and draws more metal to spikes that are beginning to grow. These can grow with tremendous mechanical force, puncture the separator, and directly connect the anode with the cathode which can create an internal short circuit. This can lead to an uncontrolled discharge reaction, which heats the cell and causes additional exothermic reactions leading to what is called thermal runaway. ORNL has developed a new technology called liquid electron microscopy. In a specially designed sample holder micro-chamber with electron-transparent windows, researchers can hold a liquid and take images of structures and particles at nanometer size. It's the first microscope holder of its kind used to investigate the inside of a battery while cycled.

  18. Coal-Sizing Auger

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1985-01-01

    Aft end of auger, like forward, face-piercing end, equipped with hard cutting bits such as diamonds. As auger breaks face, pulls broken coal lumps into jaws and forces them into hardened throat section. There, cutting bits chew up lumps: Clearance between throat and auger shaft sets maximum size for coal particles that pass through. Auger motion pushes coal particles into mixing chamber, where paddles combine them with water.

  19. [The study of ultra-fine diamond powder used in magnetic head polishing slurry].

    PubMed

    Jin, Hong-Yun; Hou, Shu-En; Pan, Yong; Xiao, Hong-Yan

    2008-05-01

    In the present paper, atomic absorption spectrometry(AAS), inductively-coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and laser Raman spectroscopy (RM) were employed to study the commercial ultra-fine diamond powders prepared by the static pressure-catalyst method and used in magnetic head polishing slurry. The results of AAS and ICP-MS indicated that there were silicon oxide, Fe, Ni, Al and some other metal elements in the ultra-fine powders. XRD patterns showed the peaks of SiO2 at 2theta = 35.6 degrees, 39.4 degrees and 59.7 degrees and diamond sharp peaks in agreement with the results above. Diamond sharp peaks implied perfect crystal and high-hardness beneficial to high-efficiency in polishing. The broader Raman band of graphite at 1 592 cm(-1) observed by Raman analysis proved graphite existing in the diamond powders. In the TEM images, the size of ultra-fine powders was estimated between 0.1 and 0.5 microm distributed in a wide scope, however, sharp edges of the powder particles was useful to polish. The ultra-fine diamond powders have many advantages, for example, high-hardness, well abrasion performance, high-polishing efficiency and being useful in magnetic head polishing slurry. But, the impurities influence the polishing efficiency, shortening its service life and the wide distribution reduces the polishing precision. Consequently, before use the powders must be purified and classified. The purity demands is 99.9% and trace silicon oxide under 0.01% should be reached. The classification demands that the particle distribution should be in a narrower scope, with the mean size of 100 nm and the percentage of particles lager than 200 nm not over 2%.

  20. Fenton-treated functionalized diamond nanoparticles as gene delivery system.

    PubMed

    Martín, Roberto; Alvaro, Mercedes; Herance, José Raúl; García, Hermenegildo

    2010-01-26

    When raw diamond nanoparticles (Dnp, 7 nm average particle size) obtained from detonation are submitted to harsh Fenton-treatment, the resulting material becomes free of amorphous soot matter and the process maintains the crystallinity, reduces the particle size (4 nm average particle size), increases the surface OH population, and increases water solubility. All these changes are beneficial for subsequent Dnp covalent functionalization and for the ability of Dnp to cross cell membranes. Fenton-treated Dnps have been functionalized with thionine and the resulting sample has been observed in HeLa cell nuclei. A triethylammonium-functionalized Dnp pairs electrostatically with a plasmid having the green fluorescent protein gene and acts as gene delivery system permitting the plasmid to cross HeLa cell membrane, something that does not occur for the plasmid alone without assistance of polycationic Dnp.

  1. Method and article of manufacture corresponding to a composite comprised of ultra nonacrystalline diamond, metal, and other nanocarbons useful for thermoelectric and other applications

    DOEpatents

    Gruen, Dieter M.

    2010-05-18

    One provides (101) disperse ultra-nanocrystalline diamond powder material that comprises a plurality of substantially ordered crystallites that are each sized no larger than about 10 nanometers. One then reacts (102) these crystallites with a metallic component. The resultant nanowire is then able to exhibit a desired increase with respect to its ability to conduct electricity while also substantially preserving the thermal conductivity behavior of the disperse ultra-nanocrystalline diamond powder material. The reaction process can comprise combining (201) the crystallites with one or more metal salts in an aqueous solution and then heating (203) that aqueous solution to remove the water. This heating can occur in a reducing atmosphere (comprising, for example, hydrogen and/or methane) to also reduce the salt to metal.

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

    NASA Astrophysics Data System (ADS)

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

    2017-12-01

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

  3. Reverse-transformation austenite structure control with micro/nanometer size

    NASA Astrophysics Data System (ADS)

    Wu, Hui-bin; Niu, Gang; Wu, Feng-juan; Tang, Di

    2017-05-01

    To control the reverse-transformation austenite structure through manipulation of the micro/nanometer grain structure, the influences of cold deformation and annealing parameters on the microstructure evolution and mechanical properties of 316L austenitic stainless steel were investigated. The samples were first cold-rolled, and then samples deformed to different extents were annealed at different temperatures. The microstructure evolutions were analyzed by optical microscopy, scanning electron microscopy (SEM), magnetic measurements, and X-ray diffraction (XRD); the mechanical properties are also determined by tensile tests. The results showed that the fraction of stain-induced martensite was approximately 72% in the 90% cold-rolled steel. The micro/nanometric microstructure was obtained after reversion annealing at 820-870°C for 60 s. Nearly 100% reversed austenite was obtained in samples annealed at 850°C, where grains with a diameter ≤ 500 nm accounted for 30% and those with a diameter > 0.5 μm accounted for 70%. The micro/nanometer-grain steel exhibited not only a high strength level (approximately 959 MPa) but also a desirable elongation of approximately 45%.

  4. Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography.

    PubMed

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N

    2015-04-24

    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Diamond family of colloidal supercrystals as phononic metamaterials

    NASA Astrophysics Data System (ADS)

    Aryana, Kiumars; Zanjani, Mehdi B.

    2018-05-01

    Colloidal crystals provide a versatile platform for designing phononic metamaterials with exciting applications for sound and heat management. New advances in the synthesis and self-assembly of anisotropic building blocks such as colloidal clusters have expanded the library of available micro- and nano-scale ordered multicomponent structures. Diamond-like supercrystals formed by such clusters and spherical particles are notable examples that include a rich family of crystal symmetries such as diamond, double diamond, zinc-blende, and MgCu2. This work investigates the design of phononic supercrystals by predicting and analyzing phonon transport properties. In addition to size variation and structural diversity, these supercrystals encapsulate different sub-lattice types within one structure. Computational models are used to calculate the effect of various parameters on the phononic spectrum of diamond-like supercrystals. The results show that structures with relatively small or large filling factors (f > 0.65 or f < 0.45) include smaller bandgaps compared to those with medium filling factors (0.65 > f > 0.45). The double diamond and zinc-blende structures render the largest bandgap size compared to the other supercrystals studied in this paper. Additionally, this article discusses the effect of incorporating various configurations of sub-lattices by selecting different material compositions for the building blocks. The results suggest that, for the same structure, there exist multiple phononic variants with drastically different band structures. This study provides a valuable insight for evaluating novel colloidal supercrystals for phononic applications and guides the future experimental work for the synthesis of colloidal structures with desired phononic behavior.

  6. Ultimate Atomic Bling: Nanotechnology of Diamonds

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

    Dahl, Jeremy

    2010-05-25

    Diamonds exist in all sizes, from the Hope Diamond to minuscule crystals only a few atoms across. The smallest of these diamonds are created naturally by the same processes that make petroleum. Recently, researchers discovered that these 'diamondoids' are formed in many different structural shapes, and that these shapes can be used like LEGO blocks for nanotechnology. This talk will discuss the discovery of these nano-size diamonds and highlight current SLAC/Stanford research into their applications in electronics and medicine.

  7. Method for producing size selected particles

    DOEpatents

    Krumdick, Gregory K.; Shin, Young Ho; Takeya, Kaname

    2016-09-20

    The invention provides a system for preparing specific sized particles, the system comprising a continuous stir tank reactor adapted to receive reactants; a centrifugal dispenser positioned downstream from the reactor and in fluid communication with the reactor; a particle separator positioned downstream of the dispenser; and a solution stream return conduit positioned between the separator and the reactor. Also provided is a method for preparing specific sized particles, the method comprising introducing reagent into a continuous stir reaction tank and allowing the reagents to react to produce product liquor containing particles; contacting the liquor particles with a centrifugal force for a time sufficient to generate particles of a predetermined size and morphology; and returning unused reagents and particles of a non-predetermined size to the tank.

  8. Influence of Interfacial Carbide Layer Characteristics on Thermal Properties of Copper-Diamond Composites (Postprint)

    DTIC Science & Technology

    2014-04-01

    wettability of diamond is not an issue. Moreover, the solid-state processing can, in principle , be carried out at relatively low temperatures even for non...capacity. q was mea- sured using Archimedes ’ method, and D was measured with laser flash technique per ASTM E1461. The speci- mens for D measurement... principle , attainable by changing the interfacial Cr3C2 layer characteristics. In an earlier study [3], for a given diamond particle size and volume

  9. Effect of Particle Size Upon Pt/SiO 2 Catalytic Cracking of n-Dodecane Under Supercritical Conditions: in situ SAXS and XANES Studies

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

    Lee, Sungwon; Lee, Sungsik; Kumbhalkar, Mrunmayi

    The endothermic cracking and dehydrogenation of n-dodecane is investigated over well-defined nanometer size platinum catalysts supported on SiO 2 to study the particle size effects in the catalytic cracking reaction, with simultaneous in situ monitoring of the particle size and oxidation state of the working catalysts by in situ SAXS (small angle X-ray scattering) and XAS (X-ray absorption spectroscopy). The selectivity toward olefins products was found dominant in the 1 nm size platinum catalysts, whereas paraffins are dominant in the 2 nm catalysts. This reveals a strong correlation between catalytic performance and catalyst size as well as the stability ofmore » the nanoparticles in supercritical condition of n-dodecane. The presented results suggest that controlling the size and geometric structure of platinum nanocatalysts could lead to a fundamentally new level of understanding of nanoscale materials by monitoring the catalysts in realistic reaction conditions.« less

  10. An Overview of Ultrafine Particles in Ambient Air

    EPA Science Inventory

    Solid and liquid particles found in the atmospheric aerosol typically cover 4 to 5 orders of magnitude from nanometers (nm) up to 100 micrometers (µm). The size range of particles of most interest to human health effects are inhalable and typically fall below 10 µm1,2....

  11. Particle size distribution control of Pt particles used for particle gun

    NASA Astrophysics Data System (ADS)

    Ichiji, M.; Akiba, H.; Nagao, H.; Hirasawa, I.

    2017-07-01

    The purpose of this study is particle size distribution (PSD) control of submicron sized Pt particles used for particle gun. In this report, simple reaction crystallization is conducted by mixing H2PtCl6 and ascorbic acid. Without the additive, obtained Pt particles have broad PSD and reproducibility of experiment is low. With seeding, Pt particles have narrow PSD and reproducibility improved. Additionally, mean particle diameter of 100-700 nm is controlled by changing seeding amount. Obtained particles are successfully characterized as Pt by XRD results. Moreover, XRD spectra indicate that obtained particles are polycrystals. These experimental results suggest that seeding consumed nucleation, as most nuclei attached on the seed surface. This mechanism virtually restricted nucleation to have narrow PSD can be obtained.

  12. An alternative method for determining particle-size distribution of forest road aggregate and soil with large-sized particles

    Treesearch

    Hakjun Rhee; Randy B. Foltz; James L. Fridley; Finn Krogstad; Deborah S. Page-Dumroese

    2014-01-01

    Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by...

  13. On the sizes and observable effects of dust particles in polar mesospheric winter echoes

    NASA Astrophysics Data System (ADS)

    Havnes, O.; Kassa, M.

    2009-05-01

    In the present paper, recent radar and heating experiments on the polar mesospheric winter echoes (PMWE) are analyzed with the radar overshoot model. The PMWE dust particles that influence the radar backscatter most likely have sizes around 3 nm. For dust to influence the electrons in the PMWE layers, it must be charged; therefore, we have discussed the charging of nanometer-sized particles and found that the photodetachment effect, where photons of energy less than the work function of the dust material can remove excess electrons, probably is dominant at sunlit conditions. For moderate and low electron densities, very few of the dust smaller than ˜3 nm will be charged. We suggest that the normal requirement that disturbed magnetospheric conditions with ionizing precipitation must be present to create observable PMWE is needed mainly to create sufficiently high electron densities to overcome the photodetachment effect and charge the PMWE dust particles. We have also suggested other possible effects of the photodetachment on the occurrence rate of the PMWE. We attribute the lack of PMWE-like radar scattering layers in the lower mesosphere during the summer not only to a lower level of turbulence than in winter but also to that dust particles are removed from these layers due to the upward wind draught in the summer mesospheric circulation system. It is likely that this last effect will completely shut off the PMWE-like radar layers in the lower parts of the mesosphere.

  14. Probing Growth-Induced Anisotropic Thermal Transport in High-Quality CVD Diamond Membranes by Multifrequency and Multiple-Spot-Size Time-Domain Thermoreflectance.

    PubMed

    Cheng, Zhe; Bougher, Thomas; Bai, Tingyu; Wang, Steven Y; Li, Chao; Yates, Luke; Foley, Brian M; Goorsky, Mark; Cola, Baratunde A; Faili, Firooz; Graham, Samuel

    2018-02-07

    The maximum output power of GaN-based high-electron mobility transistors is limited by high channel temperature induced by localized self-heating, which degrades device performance and reliability. Chemical vapor deposition (CVD) diamond is an attractive candidate to aid in the extraction of this heat and in minimizing the peak operating temperatures of high-power electronics. Owing to its inhomogeneous structure, the thermal conductivity of CVD diamond varies along the growth direction and can differ between the in-plane and out-of-plane directions, resulting in a complex three-dimensional (3D) distribution. Depending on the thickness of the diamond and size of the electronic device, this 3D distribution may impact the effectiveness of CVD diamond in device thermal management. In this work, time-domain thermoreflectance is used to measure the anisotropic thermal conductivity of an 11.8 μm-thick high-quality CVD diamond membrane from its nucleation side. Starting with a spot-size diameter larger than the thickness of the membrane, measurements are made at various modulation frequencies from 1.2 to 11.6 MHz to tune the heat penetration depth and sample the variation in thermal conductivity. We then analyze the data by creating a model with the membrane divided into ten sublayers and assume isotropic thermal conductivity in each sublayer. From this, we observe a two-dimensional gradient of the depth-dependent thermal conductivity for this membrane. The local thermal conductivity goes beyond 1000 W/(m K) when the distance from the nucleation interface only reaches 3 μm. Additionally, by measuring the same region with a smaller spot size at multiple frequencies, the in-plane and cross-plane thermal conductivities are extracted. Through this use of multiple spot sizes and modulation frequencies, the 3D anisotropic thermal conductivity of CVD diamond membrane is experimentally obtained by fitting the experimental data to a thermal model. This work provides an improved

  15. Enhancement of structure images of interstellar diamond microcrystals by image processing

    NASA Technical Reports Server (NTRS)

    O'Keefe, Michael A.; Hetherington, Crispin; Turner, John; Blake, David; Freund, Friedemann

    1988-01-01

    Image processed high resolution TEM images of diamond crystals found in oxidized acid residues of carbonaceous chondrites are presented. Two models of the origin of the diamonds are discussed. The model proposed by Lewis et al. (1987) supposes that the diamonds formed under low pressure conditions, whereas that of Blake et al (1988) suggests that the diamonds formed due to particle-particle collisions behind supernova shock waves. The TEM images of the diamond presented support the high pressure model.

  16. Hugoniot and release measurements in diamond shocked up to 26 Mbar [Hugoniot and release measurements in diamond shocked up to 25 Mbar

    DOE PAGES

    Gregor, M. C.; Fratanduono, D. E.; McCoy, C. A.; ...

    2017-04-26

    The equation of state of carbon at extreme pressures is of interest to studies of planetary ice giants and white dwarfs and to inertial con nement fusion (ICF) because diamond is used as an ablator material at the National Ignition Facility (NIF). Knowledge of both the high-pressure shock and release responses of diamond are needed to accurately model an ICF implosion and design ignition targets. This article presents Hugoniot and release data for both single-crystal diamond and the high-density carbon (HDC), comprised of nanometer-scale grains, used as a NIF ablator. Experiments were performed at the Omega Laser Facility where diamondmore » was shock-compressed to multimegabar pressures and then released into reference materials with known Hugoniots (quartz, polystyrene, silica aerogel, and liquid deuterium). Impedance matching between diamond and the standards provided the data to constrain diamond release models. Hugoniot data were obtained by impedance matching with a quartz standard and results indicate that the HDC, which is ultrananocrystalline and ~4% less dense, has a sti er Hugoniot as compared to single-crystal diamond. Accuracy of the HDC data were improved using a non-steady waves correction [D. E. Fratanduono et al., J. Appl. Phys. 116, 033517 (2014)] to determine shock velocity pro les in the opaque HDC samples.« less

  17. Heteroepitaxial diamond growth on 4H-SiC using microwave plasma chemical vapor deposition.

    PubMed

    Moore, Eric; Jarrell, Joshua; Cao, Lei

    2017-09-01

    Deposition of heteroepitaxial diamond via microwave chemical vapor deposition has been performed on a 4H-SiC substrate using bias enhanced nucleation followed by a growth step. In future work, the diamond film will serve as a protective layer for an alpha particle sensor designed to function in an electrorefiner during pyroprocessing of spent fuel. The diamond deposition on the 4H-SiC substrate was carried out using a methane-hydrogen gas mixture with varying gas flow rates. The nucleation step was conducted for 30 minutes and provided sufficient nucleation sites to grow a diamond film on various locations on the substrate. The resulting diamond film was characterized using Raman spectroscopy exhibiting the strong Raman peak at 1332 cm -1 . Scanning electron microscopy was used to observe the surface morphology and the average grain size of the diamond film was observed to be on the order of ∼2-3 μm.

  18. Status of the R&D activity on diamond particle detectors

    NASA Astrophysics Data System (ADS)

    Adam, W.; Bellini, B.; Berdermann, E.; Bergonzo, P.; de Boer, W.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Doroshenko, J.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fischer, P.; Fizzotti, F.; Furetta, C.; Gan, K. K.; Ghodbane, N.; Grigoriev, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kaplon, J.; Karl, C.; Kass, R.; Keil, M.; Knöpfle, K. T.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Menichelli, D.; Meuser, S.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Perera, L.; Pernicka, M.; Polesello, P.; Potenza, R.; Riester, J. L.; Roe, S.; Rudge, A.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Sutera, C.; Trischuk, W.; Tromson, D.; Tuve, C.; Weilhammer, P.; Wermes, N.; Wetstein, M.; Zeuner, W.; Zoeller, M.; RD42 Collaboration

    2003-09-01

    Chemical Vapor Deposited (CVD) polycrystalline diamond has been proposed as a radiation-hard alternative to silicon in the extreme radiation levels occurring close to the interaction region of the Large Hadron Collider. Due to an intense research effort, reliable high-quality polycrystalline CVD diamond detectors, with up to 270 μm charge collection distance and good spatial uniformity, are now available. The most recent progress on the diamond quality, on the development of diamond trackers and on radiation hardness studies are presented and discussed.

  19. Observation of twinning in diamond CVD films

    NASA Astrophysics Data System (ADS)

    Marciniak, W.; Fabisiak, K.; Orzeszko, S.; Rozploch, F.

    1992-10-01

    Diamond particles prepared by dc-glow-discharge enhanced HF-CVD hybrid method, from a mixture of acetone vapor and hydrogen gas have been examined by TEM, RHEED and dark field method of observation. Results suggest the presence of twinned diamond particles, which can be reconstructed by a sequence of twinning operations. Contrary to the 'stick model' of the lattice, very common five-fold symmetry of diamond microcrystals may be obtained by applying a number of edge dislocations rather than the continuous deformation of many tetrahedral C-C bonds.

  20. Evaluation of a 3D diamond detector for medical radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Kanxheri, K.; Servoli, L.; Oh, A.; Munoz Sanchez, F.; Forcolin, G. T.; Murphy, S. A.; Aitkenhead, A.; Moore, C. J.; Morozzi, A.; Passeri, D.; Bellini, M.; Corsi, C.; Lagomarsino, S.; Sciortino, S.

    2017-01-01

    Synthetic diamond has several properties that are particularly suited to applications in medical radiation dosimetry. It is tissue equivalent, not toxic and shows a high resistance to radiation damage, low leakage current and stability of response. It is an electrical insulator, robust and realizable in small size; due to these features there are several examples of diamond devices, mainly planar single-crystalline chemical vapor depositation (sCVD) diamond, used for relative dose measurement in photon beams. Thanks to a new emerging technology, diamond devices with 3-dimensional structures are produced by using laser pulses to create graphitic paths in the diamond bulk. The necessary bias voltage to operate such detector decreases considerably while the signal response and radiation resistance increase. In order to evaluate the suitability of this new technology for measuring the dose delivered by radiotherapy beams in oncology a 3D polycrystalline (pCVD) diamond detector designed for single charged particle detection has been tested and the photon beam profile has been studied. The good linearity and high sensitivity to the dose observed in the 3D diamond, opens the way to the possibility of realizing a finely segmented device with the potential for dose distribution measurement in a single exposure for small field dosimetry that nowadays is still extremely challenging.

  1. Assessing the concept of structure sensitivity or insensitivity for sub-nanometer catalyst materials

    NASA Astrophysics Data System (ADS)

    Crampton, Andrew S.; Rötzer, Marian D.; Ridge, Claron J.; Yoon, Bokwon; Schweinberger, Florian F.; Landman, Uzi; Heiz, Ueli

    2016-10-01

    The nature of the nano-catalyzed hydrogenation of ethylene, yielding benchmark information pertaining to the concept of structure sensitivity/insensitivity and its applicability at the bottom of the catalyst particle size-range, is explored with experiments on size-selected Ptn (n = 7-40) clusters soft-landed on MgO, in conjunction with first-principles simulations. As in the case of larger particles both the direct ethylene hydrogenation channel and the parallel hydrogenation-dehydrogenation ethylidyne-producing route must be considered, with the fundamental uncovering that at the < 1 nm size-scale the reaction exhibits characteristics consistent with structure sensitivity, in contrast to the structure insensitivity found for larger particles. In this size-regime, the chemical properties can be modulated and tuned by a single atom, reflected by the onset of low temperature hydrogenation at T > 150 K catalyzed by Ptn (n ≥ 10) clusters, with maximum room temperature reactivity observed for Pt13 using a pulsed molecular beam technique. Structure insensitive behavior, inherent for specific cluster sizes at ambient temperatures, can be induced in the more active sizes, e.g. Pt13, by a temperature increase, up to 400 K, which opens dehydrogenation channels leading to ethylidyne formation. This reaction channel was, however found to be attenuated on Pt20, as catalyst activity remained elevated after the 400 K step. Pt30 displayed behavior which can be understood from extrapolating bulk properties to this size range; in particular the calculated d-band center. In the non-scalable sub-nanometer size regime, however, precise control of particle size may be used for atom-by-atom tuning and manipulation of catalyzed hydrogenation activity and selectivity.

  2. Hemoglobin level and lipoprotein particle size.

    PubMed

    Hämäläinen, Päivi; Saltevo, Juha; Kautiainen, Hannu; Mäntyselkä, Pekka; Vanhala, Mauno

    2018-01-10

    Alterations in lipoprotein size are associated with increased cardiovascular disease risk. Higher hemoglobin levels may indicate a higher risk of atherosclerosis and was previously associated with obesity, metabolic syndrome, and insulin resistance. No previous studies have investigated an association between hemoglobin concentration and lipoprotein particle size. We conducted a population-based, cross-sectional study of 766 Caucasian, middle-aged subjects (341 men and 425 women) born in Pieksämäki, Finland, who were categorized into five age groups. The concentrations and sizes of lipoprotein subclass particles were analyzed by high-throughput nuclear magnetic resonance (NMR) spectroscopy. Larger very low density lipoprotein (VLDL) particle diameter was associated with higher hemoglobin concentrations in men (p = 0.003). There was a strong relationship between smaller high density lipoprotein (HDL) particle size and higher hemoglobin concentration in both men and women as well as with smaller low density lipoprotein (LDL) particle size and higher hemoglobin concentration in men and women (p < 0.001; p = 0.009, p = 0.008). VLDL particle concentration had a moderate positive correlation with hemoglobin concentration (r = 0.15; p < 0.001). LDL particle concentration showed a statistical trend suggesting increasing particle concentration with increasing hemoglobin levels (r = 0.08; p = 0.05). Higher hemoglobin levels are associated with larger VLDL, smaller LDL, and smaller HDL particle sizes and increasing amounts of larger VLDL and smaller LDL particles. This suggests that a higher hemoglobin concentration is associated with an unfavorable lipoprotein particle profile that is part of states that increase cardiovascular disease risk like diabetes and metabolic syndrome.

  3. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

    PubMed Central

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-01-01

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

  4. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

    PubMed

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-02-29

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

  5. Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

    2016-02-01

    Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

  6. Method of forming fluorine-bearing diamond layer on substrates, including tool substrates

    DOEpatents

    Chang, R. P. H.; Grannen, Kevin J.

    2002-01-01

    A method of forming a fluorine-bearing diamond layer on non-diamond substrates, especially on tool substrates comprising a metal matrix and hard particles, such as tungsten carbide particles, in the metal matrix. The substrate and a fluorine-bearing plasma or other gas are then contacted under temperature and pressure conditions effective to nucleate fluorine-bearing diamond on the substrate. A tool insert substrate is treated prior to the diamond nucleation and growth operation by etching both the metal matrix and the hard particles using suitable etchants.

  7. Surface Redox Chemistry of Immobilized Nanodiamond: Effects of Particle Size and Electrochemical Environment

    NASA Astrophysics Data System (ADS)

    Gupta, S.; McDonald, B.; Carrizosa, S. B.

    2017-07-01

    The size of the diamond particle is tailored to nanoscale (nanodiamond, ND), and the ND surface is engineered targeting specific (electrochemical and biological) applications. In this work, we investigated the complex surface redox chemistry of immobilized ND layer on conductive boron-doped diamond electrode with a broad experimental parameter space such as particle size (nano versus micron), scan rate, pH (cationic/acidic versus anionic/basic), electrolyte KCl concentration (four orders of magnitude), and redox agents (neutral and ionic). We reported on the significant enhancement of ionic currents while recording reversible oxidation of neutral ferrocene methanol (FcMeOH) by almost one order of magnitude than traditional potassium ferricyanide (K3Fe(CN)6) redox agent. The current enhancement is inversely related to ND particle diameter in the following order: 1 μm << 1000 nm < 100 nm < 10 nm ≤ 5 nm < 2 nm. We attribute the current enhancement to concurrent electrocatalytic processes, i.e. the electron transfer between redox probes and electroactive surface functional (e.g. hydroxyl, carboxyl, epoxy) moieties and the electron transfer mediated by adsorbed FcMeOH+ (or Fe(CN) 6 3+ ) ions onto ND surface. The first process is pH dependent since it depends upon ND surface functionalities for which the electron transfer is coupled to proton transfer. The adsorption mediated process is observed most apparently at slower scan rates owing to self-exchange between adsorbed FcMeOH+ ions and FcMeOH redox agent molecules in diffusion-limited bulk electrolyte solution. Alternatively, it is hypothesized that the surface functionality and defect sites ( sp 2-bonded C shell and unsaturated bonds) give rise to surface electronic states with energies within the band gap (midgap states) in undoped ND. These surface states serve as electron donors (and acceptors) depending upon their bonding (and antibonding) character and, therefore, they can support electrocatalytic redox

  8. Effect of particle size distribution on 3D packings of spherical particles

    NASA Astrophysics Data System (ADS)

    Taiebat, Mahdi; Mutabaruka, Patrick; Pellenq, Roland; Radjai, Farhang

    2017-06-01

    We use molecular dynamics simulations of frictionless spherical particles to investigate a class of polydisperse granular materials in which the particle size distribution is uniform in particle volumes. The particles are assembled in a box by uniaxial compaction under the action of a constant stress. Due to the absence of friction and the nature of size distribution, the generated packings have the highest packing fraction at a given size span, defined as the ratio α of the largest size to the smallest size. We find that, up to α = 5, the packing fraction is a nearly linear function of α. While the coordination number is nearly constant due to the isostatic nature of the packings, we show that the connectivity of the particles evolves with α. In particular, the proportion of particles with 4 contacts represents the largest proportion of particles mostly of small size. We argue that this particular class of particles occurs as a result of the high stability of local configurations in which a small particle is stuck by four larger particles.

  9. Tuning Precursor Reactivity toward Nanometer-Size Control in Palladium Nanoparticles Studied by in Situ Small Angle X-ray Scattering

    DOE PAGES

    Wu, Liheng; Lian, Huada; Willis, Joshua J.; ...

    2018-01-03

    Synthesis of monodisperse nanoparticles (NPs) with precisely controlled size is critical for understanding their size-dependent properties. Although significant synthetic developments have been achieved, it is still challenging to synthesize well-defined NPs in a predictive way due to a lack of in-depth mechanistic understanding of reaction kinetics. Here we use synchrotron-based small-angle X-ray scattering (SAXS) to monitor in situ the formation of palladium (Pd) NPs through thermal decomposition of Pd–TOP (TOP: trioctylphosphine) complex via the “heat-up” method. We systematically study the effects of different ligands, including oleylamine, TOP, and oleic acid, on the formation kinetics of Pd NPs. Through quantitative analysismore » of the real-time SAXS data, we are able to obtain a detailed picture of the size, size distribution, and concentration of Pd NPs during the syntheses, and these results show that different ligands strongly affect the precursor reactivity. We find that oleylamine does not change the reactivity of the Pd–TOP complex but promote the formation of nuclei due to strong ligand–NP binding. On the other hand, TOP and oleic acid substantially change the precursor reactivity over more than an order of magnitude, which controls the nucleation kinetics and determines the final particle size. A theoretical model is used to demonstrate that the nucleation and growth kinetics are dependent on both precursor reactivity and ligand–NP binding affinity, thus providing a framework to explain the synthesis process and the effect of the reaction conditions. Quantitative understanding of the impacts of different ligands enables the successful synthesis of a series of monodisperse Pd NPs in the broad size range from 3 to 11 nm with nanometer-size control, which serve as a model system to study their size-dependent catalytic properties. Furthermore, the in situ SAXS probing can be readily extended to other functional NPs to greatly advance

  10. Tuning Precursor Reactivity toward Nanometer-Size Control in Palladium Nanoparticles Studied by in Situ Small Angle X-ray Scattering

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

    Wu, Liheng; Lian, Huada; Willis, Joshua J.

    Synthesis of monodisperse nanoparticles (NPs) with precisely controlled size is critical for understanding their size-dependent properties. Although significant synthetic developments have been achieved, it is still challenging to synthesize well-defined NPs in a predictive way due to a lack of in-depth mechanistic understanding of reaction kinetics. Here we use synchrotron-based small-angle X-ray scattering (SAXS) to monitor in situ the formation of palladium (Pd) NPs through thermal decomposition of Pd–TOP (TOP: trioctylphosphine) complex via the “heat-up” method. We systematically study the effects of different ligands, including oleylamine, TOP, and oleic acid, on the formation kinetics of Pd NPs. Through quantitative analysismore » of the real-time SAXS data, we are able to obtain a detailed picture of the size, size distribution, and concentration of Pd NPs during the syntheses, and these results show that different ligands strongly affect the precursor reactivity. We find that oleylamine does not change the reactivity of the Pd–TOP complex but promote the formation of nuclei due to strong ligand–NP binding. On the other hand, TOP and oleic acid substantially change the precursor reactivity over more than an order of magnitude, which controls the nucleation kinetics and determines the final particle size. A theoretical model is used to demonstrate that the nucleation and growth kinetics are dependent on both precursor reactivity and ligand–NP binding affinity, thus providing a framework to explain the synthesis process and the effect of the reaction conditions. Quantitative understanding of the impacts of different ligands enables the successful synthesis of a series of monodisperse Pd NPs in the broad size range from 3 to 11 nm with nanometer-size control, which serve as a model system to study their size-dependent catalytic properties. Furthermore, the in situ SAXS probing can be readily extended to other functional NPs to greatly advance

  11. Diamond bio electronics.

    PubMed

    Linares, Robert; Doering, Patrick; Linares, Bryant

    2009-01-01

    The use of diamond for advanced applications has been the dream of mankind for centuries. Until recently this dream has been realized only in the use of diamond for gemstones and abrasive applications where tons of diamonds are used on an annual basis. Diamond is the material system of choice for many applications, but its use has historically been limited due to the small size, high cost, and inconsistent (and typically poor) quality of available diamond materials until recently. The recent development of high quality, single crystal diamond crystal growth via the Chemical Vapor Deposition (CVD) process has allowed physcists and increasingly scientists in the life science area to think beyond these limitations and envision how diamond may be used in advanced applications ranging from quantum computing, to power generation and molecular imaging, and eventually even diamond nano-bots. Because of diamond's unique properties as a bio-compatible material, better understanding of diamond's quantum effects and a convergence of mass production, semiconductor-like fabrication process, diamond now promises a unique and powerful key to the realization of the bio-electronic devices being envisioned for the new era of medical science. The combination of robust in-the-body diamond based sensors, coupled with smart bio-functionalized diamond devices may lead to diamond being the platform of choice for bio-electronics. This generation of diamond based bio-electronic devices would contribute substantially to ushering in a paradigm shift for medical science, leading to vastly improved patient diagnosis, decrease of drug development costs and risks, and improved effectiveness of drug delivery and gene therapy programs through better timed and more customized solutions.

  12. A Versatile Methodology Using Sol-Gel, Supercritical Extraction, and Etching to Fabricate a Nitramine Explosive: Nanometer HNIW

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Song, Xiaolan; Song, Dan; Jiang, Wei; Liu, Hongying; Li, Fengsheng

    2013-01-01

    A combinative method with three steps was developed to fabricate HNIW (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtziane) nanoexplosives with the gas anti-solvent (GAS) method improved by introducing a gel frame to limit the overgrowth of recrystallized particles and an acid-assistant to remove the used frame. Forming the mixed gel, by locking the explosive solution into a wet gel whose volume was divided by the networks, was the key for the fabrication. As demonstrated by scanning electron microscopy (SEM) analysis, a log-normal size distribution of nano-HNIW indicated that about 74.4% of the particles had sizes <120 nm and maximum particle size was ∼300 nm. Energy-dispersive X-ray spectroscopy (EDS) and infrared (IR) characterizations showed that the aerogel embedded with nanoexplosive particles was dissolved in hydrochloric acid solution, and the raw ɛ-HNIW was mostly transformed into the α phase (nano-HNIW) during recrystallization. Nano-HNIW exhibited impact and friction sensitivity almost equal to those of raw HNIW, within experimental error. Thermal analysis showed that the decomposition peak temperature decreased by more than 10°C and that the heat release increased by 42.5% when the particle size of HNIW was at the nanometer scale.

  13. Sensitivity of bacteria to diamond nanoparticles of various size differs in gram-positive and gram-negative cells.

    PubMed

    Beranová, Jana; Seydlová, Gabriela; Kozak, Halyna; Benada, Oldřich; Fišer, Radovan; Artemenko, Anna; Konopásek, Ivo; Kromka, Alexander

    2014-02-01

    In this study, the influence of the size and surface termination of diamond nanoparticles (DNPs) on their antibacterial activity against Escherichia coli and Bacillus subtilis was assessed. The average size and distribution of DNPs were determined by dynamic light scattering and X-ray diffraction techniques. The chemical composition of the DNPs studied by X-ray photoelectron spectroscopy showed that DNPs > 5 nm and oxidized particles have a higher oxygen content. The antibacterial potential of DNPs was assessed by the viable count method. In general, E. coli exhibited a higher sensitivity to DNPs than B. subtilis. However, in the presence of all the DNPs tested, the B. subtilis colonies exhibited altered size and morphology. Antibacterial activity was influenced not only by DNP concentration but also by DNP size and form. Whereas untreated 5-nm DNPs were the most effective against E. coli, the antibacterial activity of 18-50-nm DNPs was higher against B. subtilis. Transmission electron microscopy showed that DNPs interact with the bacterial surface, probably affecting vital cell functions. We propose that DNPs interfere with the permeability of the bacterial cell wall and/or membrane and hinder B. subtilis colony spreading. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  14. Architectural design of diamond-like carbon coatings for long-lasting joint replacements.

    PubMed

    Liu, Yujing; Zhao, Xiaoli; Zhang, Lai-Chang; Habibi, Daryoush; Xie, Zonghan

    2013-07-01

    Surface engineering through the application of super-hard, low-friction coatings as a potential approach for increasing the durability of metal-on-metal replacements is attracting significant attention. In this study innovative design strategies are proposed for the development of diamond-like-carbon (DLC) coatings against the damage caused by wear particles on the joint replacements. Finite element modeling is used to analyze stress distributions induced by wear particles of different sizes in the newly-designed coating in comparison to its conventional monolithic counterpart. The critical roles of architectural design in regulating stress concentrations and suppressing crack initiation within the coatings is elucidated. Notably, the introduction of multilayer structure with graded modulus is effective in modifying the stress field and reducing the magnitude and size of stress concentrations in the DLC diamond-like-carbon coatings. The new design is expected to greatly improve the load-carrying ability of surface coatings on prosthetic implants, in addition to the provision of damage tolerance through crack arrest. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Particle size and support effects in electrocatalysis.

    PubMed

    Hayden, Brian E

    2013-08-20

    Researchers increasingly recognize that, as with standard supported heterogeneous catalysts, the activity and selectivity of supported metal electrocatalysts are influenced by particle size, particle structure, and catalyst support. Studies using model supported heterogeneous catalysts have provided information about these effects. Similarly, model electrochemical studies on supported metal electrocatalysts can provide insight into the factors determining catalytic activity. High-throughput methods for catalyst synthesis and screening can determine systematic trends in activity as a function of support and particle size with excellent statistical certainty. In this Account, we describe several such studies investigating methods for dispersing precious metals on both carbon and oxide supports, with particular emphasis on the prospects for the development of low-temperature fuel-cell electrocatalysts. One key finding is a decrease in catalytic activity with decreasing particle size independent of the support for both oxygen reduction and CO oxidation on supported gold and platinum. For these reactions, there appears to be an intrinsic particle size effect that results in a loss of activity at particle sizes below 2-3 nm. A titania support, however, also increases activity of gold particles in the electrooxidation of CO and in the reduction of oxygen, with an optimum at 3 nm particle size. This optimum may represent the superposition of competing effects: a titania-induced enhanced activity versus deactivation at small particle sizes. The titania support shows catalytic activity at potentials where carbon-supported and bulk-gold surfaces are normally oxidized and CO electrooxidation is poisoned. On the other hand, platinum on amorphous titania shows a different effect: the oxidation reduction reaction is strongly poisoned in the same particle size range. We correlated the influence of the titania support with titania-induced changes in the surface redox behavior of

  16. Uncovering the Physical Basis Connecting Environment and Tribological Performance of Ultrananocrystalline Diamond

    DTIC Science & Technology

    2014-04-17

    measured with an infrared pyrometer (550-3200°C). The substrates were coated with diamond nanoparticles (ITC Inc.) which serve as nucleation sites...wafers were seeded with nano-diamond particles prior to film growth to provide nucleation sites for diamond growth. To study the effect of surface...wafers are appropriate to generate uniform seeding. AFM tips were seeded with nano-diamond particles prior to coating with NCD to provide nucleation

  17. Effect of varying total mixed ration particle size on rumen digesta and fecal particle size and digestibility in lactating dairy cows.

    PubMed

    Maulfair, D D; Fustini, M; Heinrichs, A J

    2011-07-01

    The objective of this experiment was to evaluate the effects of feeding rations of different particle sizes on rumen digesta and fecal matter particle size. Four rumen-cannulated, multiparous, Holstein cows (104±15 d in milk) were randomly assigned to treatments in a 4×4 Latin square design. The diets consisted of 29.4% corn silage, 22.9% ground corn, 17.6% alfalfa haylage, and 11.8% dry grass hay [20% of forage dry matter (DM)] on a DM basis. Dry grass hay was chopped to 4 different lengths to vary the total mixed ration (TMR) particle size. Geometric mean particle sizes of the rations were 4.46, 5.10, 5.32, and 5.84 mm for short, medium, long, and extra long diets, respectively. The ration affected rumen digesta particle size for particles ≥3.35 mm, and had no effect on distribution of particles <3.35 mm. All rumen digesta particle size fractions varied by time after feeding, with soluble particle fractions increasing immediately after feeding and 0.15, 0.6, and 1.18-mm particle size fractions decreasing slightly after feeding. Particle fractions >1.18 mm had ration by time interactions. Fecal neutral detergent fiber (NDF) and indigestible NDF concentrations decreased with increasing TMR particle size. Fecal particle size expressed as total geometric mean particle length followed this same tendency. Fecal particle size, expressed as retained geometric mean particle length, averaged 1.13 mm with more than 36% of particles being larger than 1.18 mm. All fecal nutrient concentrations measured were significantly affected by time after feeding, with NDF and indigestible NDF increasing after feeding and peaking at about 12h later and then decreasing to preprandial levels. Starch concentrations were determined to have the opposite effect. Additionally, apparent digestibility of diet nutrients was analyzed and DM digestibility tended to decrease with increasing TMR particle size, whereas other nutrient digestibilities were not different among rations. These results

  18. Physical characterization and in vitro biological impact of highly aggregated antibodies separated into size-enriched populations by fluorescence-activated cell sorting

    PubMed Central

    Telikepalli, Srivalli; Shinogle, Heather E.; Thapa, Prem S.; Kim, Jae Hyun; Deshpande, Meghana; Jawa, Vibha; Middaugh, C. Russell; Narhi, Linda O.; Joubert, Marisa K.; Volkin, David B.

    2015-01-01

    An IgG2 monoclonal antibody (mAb) solution was subjected to stirring, generating high concentrations of nanometer and subvisible particles, which were then successfully size enriched into different size bins by low speed centrifugation or a combination of gravitational sedimentation and Fluorescence-Activated Cell Sorting (FACS). The size-fractionated mAb particles were assessed for their ability to elicit the release of cytokines from a population of donor-derived human peripheral blood mononuclear cells (PBMC) at two phases of the immune response. Fractions enriched in nanometer-sized particles showed a lower response than those enriched in micron-sized particles in this assay. Particles of 5–10 μm in size displayed elevated cytokine release profiles compared to other size ranges. Stir-stressed mAb particles had amorphous morphology, contained protein with partially altered secondary structure, elevated surface hydrophobicity (compared to controls), and trace levels of elemental fluorine. FACS size-enriched the mAb particle samples, yet did not notably alter the overall morphology or composition of particles as measured by Microflow imaging, Transmission Electron Microscopy, and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy. The utility and limitations of FACS for size separation of mAb particles and potential of in-vitro PBMC studies to rank order the immunogenic potential of various types of mAb particles is discussed. PMID:25753756

  19. The influence of particle size distribution on dose conversion factors for radon progeny in the underground excavations of hard coal mine.

    PubMed

    Skubacz, Krystian; Wojtecki, Łukasz; Urban, Paweł

    2016-10-01

    In Polish underground mines, hazards caused by enhanced natural radioactivity occur. The sources of radiation exposure are short-lived radon decay products, mine waters containing radium 226 Ra and 228 Ra and the radioactive sediments that can precipitate out of these waters. For miners, the greatest exposure is usually due to short-lived radon decay products. The risk assessment is based on the measurement of the total potential alpha energy concentration (PAEC) and the evaluation of the related dose by using the dose conversion factor as recommended by relevant legal requirements. This paper presents the results of measurements of particle size distributions of ambient aerosols in an underground hard coal mine, the assessment of the radioactive particle size distribution of the short-lived radon decay products and the corresponding values of dose conversion factors. The measurements of the ambient airborne particle size distribution were performed in the range from a few nanometers to about 20 μm. The study therefore included practically the whole class of respirable particles. The results showed that the high concentration of ultrafine and fine aerosols measured can significantly affect the value of the dose conversion factors, and consequently the corresponding committed effective dose, to which the miners can be exposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Diamond Lattice Colloidal Crystals from Binary DNA-grafted Microspheres

    NASA Astrophysics Data System (ADS)

    Crocker, John; Wang, Yifan; Jenkins, Ian; McGinley, James; Sinno, Talid

    Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals from a binary suspension of sub-micron polymer microspheres with synthetic DNA grafted to their surfaces. While diamond symmetry crystals have previously been grown from much smaller nanoparticles, none of those methods appear workable for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light. Intriguingly, matched simulations fail to nucleate or grow B32 crystals from suspension; nor have they been predicted on the basis of theoretical arguments. We conjecture that the B32 crystals may form via transformation from a precursor with a different lattice structure in the bulk or on its surface. The feasibility of converting our self-assembled crystals into diamond-symmetry photonic templates will be discussed. This finding suggests that still other unexpected microstructures may be accessible using this approach. US National Science Foundation, CBET- 1403237.

  1. Mechanical and Thermal Properties of Pulsed Electric Current Sintered (PECS) Cu-Diamond Compacts

    NASA Astrophysics Data System (ADS)

    Ritasalo, Riina; Kanerva, Ulla; Ge, Yanling; Hannula, Simo-Pekka

    2014-04-01

    In this work, dispersion strengthening of copper by diamonds is explored. In particular, the influence of 50- and 250-nm diamonds at contents of 3 and 6 vol. pct on the mechanical and thermal properties of pulsed electric current sintered (PECS) Cu composites is studied. The composite powders were prepared by mechanical alloying in argon atmosphere using a high-energy vibratory ball mill. The PECS compacts prepared had high density (>97 pct of T.D.) with quite evenly distributed diamonds. The effectiveness of dispersoids in increasing the microhardness was more pronounced at a smaller particle size and larger volume fraction, explained by Hall-Petch and Orowan strengthening models. The microhardness of Cu with 6 and 3 vol. pct nanodiamonds and pure sm-Cu (submicron-sized Cu) was 1.77, 1.46, and 1.02 GPa, respectively. In annealing experiments at 623 K to 873 K (350 °C to 600 °C), the composites with 6 vol. pct dispersoids retained their hardness better than those with less dispersoids or sm-Cu. The coefficient of thermal expansion was lowered when diamonds were added, being the lowest at about 14 × 10-6 K-1 between 473 K and 573 K (200 °C and 300 °C). Good bonding between the copper and diamond was qualitatively demonstrated by nanoindentation. In conclusion, high-quality Cu-diamond composites can be produced by PECS with improved strength and better thermal stability than for sm-Cu.

  2. Microstructural Evolution of Nanocrystalline Diamond Films Due to CH4/Ar/H2 Plasma Post-Treatment Process.

    PubMed

    Lin, Sheng-Chang; Yeh, Chien-Jui; Manoharan, Divinah; Leou, Keh-Chyang; Lin, I-Nan

    2015-10-07

    Plasma post-treatment process was observed to markedly enhance the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films. TEM examinations reveal that the prime factor which improves the EFE properties of these films is the coalescence of ultrasmall diamond grains (∼5 nm) forming large diamond grains about hundreds of nanometers accompanied by the formation of nanographitic clusters along the grain boundaries due to the plasma post-treatment process. OES studies reveal the presence of large proportion of atomic hydrogen and C2 (or CH) species, which are the main ingredients that altered the granular structure of the UNCD films. In the post-treatment process, the plasma interacts with the diamond films by a diffusion process. The recrystallization of diamond grains started at the surface region of the material, and the interaction zone increased with the post-treatment period. The entire diamond film can be converted into a nanocrystalline granular structure when post-treated for a sufficient length of time.

  3. The biological response to nanometre-sized polymer particles.

    PubMed

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L; Ingham, Eileen; Fisher, John; Tipper, Joanne L

    2015-09-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1-1.0μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20nm, 60nm, 200nm and 1.0μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100μm(3) particles per cell after 12 and 24h. The micrometre-size UHMWPE wear particles (0.1-1.0μm) and 60nm, 200nm and 1.0μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  4. The biological response to nanometre-sized polymer particles

    PubMed Central

    Liu, Aiqin; Richards, Laura; Bladen, Catherine L.; Ingham, Eileen; Fisher, John; Tipper, Joanne L.

    2015-01-01

    Recently, nanometre-sized UHMWPE particles generated from hip and knee replacements have been identified in vitro and in vivo. UHMWPE particles in the 0.1–1.0 μm size range have been shown to be more biologically active than larger particles, provoking an inflammatory response implicated in late aseptic loosening of total joint replacements. The biological activity of nanometre-sized particles has not previously been studied. The biological response to clinically-relevant UHMWPE wear particles including nanometre-sized and micrometre-sized, along with polystyrene particles (FluoSpheres 20 nm, 60 nm, 200 nm and 1.0 μm), and nanometre-sized model polyethylene particles (Ceridust 3615®), was determined in terms of osteolytic cytokine release from primary human peripheral blood mononuclear cells (PBMNCs). Nanometre-sized UHMWPE wear particles, nanometre-sized Ceridust 3615® and 20 nm FluoSpheres had no significant effect on TNF-α, IL-1β, IL-6 and IL-8 release from PBMNCs at a concentration of 100 μm3 particles per cell after 12 and 24 h. The micrometre-size UHMWPE wear particles (0.1–1.0 μm) and 60 nm, 200 nm and 1.0 μm FluoSpheres caused significantly elevated osteolytic cytokine release from PBMNCs. These results indicated that particles below circa 50 nm fail to activate PBMNCs and that particle size, composition and morphology played a crucial role in cytokine release by particle stimulated macrophages. PMID:26004221

  5. Depth of Formation of Ferropericlase Included in Super-Deep Diamonds

    NASA Astrophysics Data System (ADS)

    Anzolini, C.; Nestola, F.; Gianese, A.; Nimis, P.; Harris, J. W.

    2017-12-01

    Super-deep diamonds are believed to have formed at depths of at least 300 km depth (Harte, 2010). A common mineral inclusion in these diamonds is ferropericlase, (Mg,Fe)O (see Kaminsky, 2012 and references therein). Ferropericlase (fPer) is the second most abundant mineral in the lower mantle, comprising approximately 16-20 wt% (660 to 2900 km depth), and inclusions of fPer in diamond are often considered to indicate a lower-mantle origin (Harte et al., 1999). Samples from São Luiz/Juina, Brazil, are noteworthy for containing nanometer-sized magnesioferrite (Harte et al., 1999; Wirth et al., 2014; Kaminsky et al., 2015; Palot et al., 2016). Based upon a phase diagram valid for 1 atm, such exsolutions would place the origin of this assemblage in the uppermost part of the lower mantle. However, a newly reported phase diagram for magnesioferrite demonstrates that the latter is not stable at such pressures and, thus, it cannot exsolve directly from fPer at lower-mantle conditions (Uenver-Thiele et al., 2017). Here we report the investigation of two fPer inclusions, extracted from a single São Luiz diamond, by single-crystal X-ray diffraction and field emission scanning electron microscopy. Both techniques showed micrometer-sized exsolutions of magnesioferrite within the two fPers. We also completed elastic geobarometry (see Angel et al., 2015), which determined an estimate for the depth of entrapment of the two ferropericlase - diamond pairs. In the temperature range between 1273 and 1773 K, pressures varied between 9.88 and 12.34 GPa (325-410 km depth) for one inclusion and between 10.69 and 13.16 GPa (350-440 km depth) for the other one. These results strengthen the hypothesis that solitary fPer inclusions might not be reliable markers for a lower-mantle provenance. This work was supported by Fondazione CaRiPaRo and ERC-2012-StG 307322 to FN. Angel, R.J., et al. (2015) Russ Geol Geophys, 56, 211-220; Harte, B. (2010) Mineral Mag, 74, 189-215; Harte, B., et al

  6. Recent results on CVD diamond radiation sensors

    NASA Astrophysics Data System (ADS)

    Weilhammer, P.; Adam, W.; Bauer, C.; Berdermann, E.; Bogani, F.; Borchi, E.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; v. d. Eijk, R.; van Eijk, B.; Fallou, A.; Fish, D.; Fried, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Knopfle, K. T.; Krammer, M.; Manfredi, P. F.; Meier, D.; LeNormand; Pan, L. S.; Pernegger, H.; Pernicka, M.; Plano, R.; Re, V.; Riester, J. L.; Roe, S.; Roff; Rudge, A.; Schieber, M.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Tapper, R. J.; Tesarek, R.; Thomson, G. B.; Trawick, M.; Trischuk, W.; Turchetta, R.; RD 42 Collaboration

    1998-02-01

    CVD diamond radiation sensors are being developed for possible use in trackers in the LHC experiments. The diamond promises to be radiation hard well beyond particle fluences that can be tolerated by Si sensors. Recent results from the RD 42 collaboration on charge collection distance and on radiation hardness of CVD diamond samples will be reported. Measurements with diamond tracking devices, both strip detectors and pixel detectors, will be discussed. Results from beam tests using a diamond strip detector which was read out with fast, 25 ns shaping time, radiation-hard pipeline electronics will be presented.

  7. Method for determining aerosol particle size device for determining aerosol particle size

    DOEpatents

    Novick, Vincent J.

    1998-01-01

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data.

  8. A general approach to homogeneous sub-nanometer metallic particle/graphene composites by S-coordinator

    NASA Astrophysics Data System (ADS)

    Wang, Senhao; Wang, Wei; Gu, Shangzhi; Zhang, Guoxin; Song, Ningning

    2018-05-01

    In this study, sulphur-modified reduced graphene oxide (S-rGO) was employed as substrate to investigate the growth mechanism of metal and metallic nanoparticles (NPs). It is observed that the monodispersed Au, SnO2, FeO(OH) and Co3S4 NPs in sub-nanometer (sub-nm) with narrow size distribution were successfully anchored on S-rGO, respectively. The results indicate that the S contained radicals, viz. the Cdbnd S and Csbnd Ssbnd C functional groups play an important role in determining the homogeneous distribution of NPs on S-rGO by providing active sites for the NPs anchoring and nucleation. In additional, as anode materials for lithium ion batteries (LIBs), the as-synthesized sub-nm sized Co3S4/S-rGO and SnO2/S-rGO composites show excellent Li storage performance. It could be stabilized at ca. 600 mAh/g after formation cycle with the coulombic efficiency of 98%. It is expected that the strategy of growing sub-nm sized metallic component onto graphene by applying sulphur functionalities could be utilized as a general method to prepare monodispersed graphene-based NPs with other metals, especially with transition metals in sub-nm sizes.

  9. Thermodynamics Of Common Atmospheric Particles On The Nanoscale

    NASA Astrophysics Data System (ADS)

    Onasch, T.; Han, J.; Oatis, S.; Brechtel, F.; Imre, D. G.

    2002-12-01

    A significant fraction of atmospheric particles are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence. Recent field studies have observed large nucleation events of hygroscopic particles and note discrepancies between predicted and observed particle growth rates after nucleation. These growth rates are governed, in part, by the thermodynamic properties of particles only a few nanometers in diameter. However, little thermodynamic information is currently available for nanometer?sized particles. The Kelvin relation indicates that the surface tension of a particle less than 100nm in diameter can dramatically affect the thermodynamics, and surface states may begin to influence the bulk physical properties in these small particles with high surface to volume ratios. In this context, we are investigating the thermodynamic properties, including pre-deliquescence water adsorption, deliquescence, efflorescence, and supersaturated particle compositions of nanoparticles with mobility diameters in the range of 5 to 50 nm. We have developed a temperature and humidity-controlled laboratory-based Nano Differential Mobility Analyzer (NDMA) system to characterize the hygroscopic properties of the common atmospheric salt particles as a function of size. Two different aerosol generation systems have been used to cover the full size range. The first system (less than 20nm diameter) relies on an Atomizer (TSI 3076) to produce particles which are size?selected using an initial DMA. For particle sizes smaller than 20 nm, the Electrospray Aerosol Generator (EAG, TSI 3480) has been employed as a particle source. The EAG characteristically provides narrow size distributions, comparable to the monodisperse size distribution from a DMA, but with higher number concentrations. Once generated, the monodisperse aerosol flow is then conditioned with respect to humidity at a constant temperature and subsequently analyzed using a TSI Ultrafine CPC (Model 3010

  10. Indetermination of particle sizing by laser diffraction in the anomalous size ranges

    NASA Astrophysics Data System (ADS)

    Pan, Linchao; Ge, Baozhen; Zhang, Fugen

    2017-09-01

    The laser diffraction method is widely used to measure particle size distributions. It is generally accepted that the scattering angle becomes smaller and the angles to the location of the main peak of scattered energy distributions in laser diffraction instruments shift to smaller values with increasing particle size. This specific principle forms the foundation of the laser diffraction method. However, this principle is not entirely correct for non-absorbing particles in certain size ranges and these particle size ranges are called anomalous size ranges. Here, we derive the analytical formulae for the bounds of the anomalous size ranges and discuss the influence of the width of the size segments on the signature of the Mie scattering kernel. This anomalous signature of the Mie scattering kernel will result in an indetermination of the particle size distribution when measured by laser diffraction instruments in the anomalous size ranges. By using the singular-value decomposition method we interpret the mechanism of occurrence of this indetermination in detail and then validate its existence by using inversion simulations.

  11. Surface effects on ionic Coulomb blockade in nanometer-size pores

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V.; Di Ventra, Massimiliano

    2018-01-01

    Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying ‘crystal-like’ structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

  12. Surface effects on ionic Coulomb blockade in nanometer-size pores.

    PubMed

    Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V; Ventra, Massimiliano Di

    2018-01-12

    Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying 'crystal-like' structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

  13. Diamond-Like Carbon Nanorods and Fabrication Thereof

    NASA Technical Reports Server (NTRS)

    Varshney, Deepak (Inventor); Makarov, Vladimir (Inventor); Morell, Gerardo (Inventor); Saxena, Puja (Inventor); Weiner, Brad (Inventor)

    2017-01-01

    Novel sp. (sup 3) rich diamond-like carbon (DLC) nanorod films were fabricated by hot filament chemical vapor deposition technique. The results are indicative of a bottom-up self-assembly synthesis process, which results in a hierarchical structure that consists of microscale papillae comprising numerous nanorods. The papillae have diameters ranging from 2 to 4 microns and the nanorods have diameters in the 35-45 nanometer range. A growth mechanism based on the vapor liquid-solid mechanism is proposed that accounts for the morphological aspects in the micro- and nano-scales.

  14. In situ observation of quasimelting of diamond and reversible graphite-diamond phase transformations.

    PubMed

    Huang, J Y

    2007-08-01

    Because of technique difficulties in achieving the extreme high-pressure and high-temperature (HPHT) simultaneously, direct observation of the structures of carbon at extreme HPHT conditions has not been possible. Banhart and Ajayan discovered remarkably that carbon onions can act as nanoscopic pressure cells to generate high pressures. By heating carbon onions to approximately 700 degrees C and under electron beam irradiation, the graphite-to-diamond transformation was observed in situ by transmission electron microscopy (TEM). However, the highest achievable temperature in a TEM heating holder is less than 1000 degrees C. Here we report that, by using carbon nanotubes as heaters and carbon onions as high-pressure cells, temperatures higher than 2000 degrees C and pressures higher than 40 GPa were achieved simultaneously in carbon onions. At such HPHT conditions and facilitated by electron beam irradiation, the diamond formed in the carbon onion cores frequently changed its shape, size, orientation, and internal structure and moved like a fluid, implying that it was in a quasimelting state. The fluctuation between the solid phase of diamond and the fluid/amorphous phase of diamond-like carbon, and the changes of the shape, size, and orientation of the solid diamond, were attributed to the dynamic crystallization of diamond crystal from the quasimolten state and the dynamic graphite-diamond phase transformations. Our discovery offers unprecedented opportunities to studying the nanostructures of carbon at extreme conditions in situ and at an atomic scale.

  15. Method for determining aerosol particle size, device for determining aerosol particle size

    DOEpatents

    Novick, V.J.

    1998-10-06

    A method for determining the mass median diameter D of particles contained in a fluid is provided wherein the data of the mass of a pre-exposed and then a post-exposed filter is mathematically combined with data concerning the pressure differential across the same filter before and then after exposure to a particle-laden stream. A device for measuring particle size is also provided wherein the device utilizes the above-method for mathematically combining the easily quantifiable data. 2 figs.

  16. Development of a small-sized generator of ozonated water using an electro-conductive diamond electrode.

    PubMed

    Sekido, Kota; Kitaori, Noriyuki

    2008-12-01

    A small-sized generator of ozonated water was developed using an electro-conductive diamond. We studied the optimum conditions for producing ozonated water. As a result, we developed a small-sized generator of ozonated water driven by a dry-cell for use in the average household. This generator was easily able to produce ozonated water with an ozone concentration (over 4 mg/L) sufficient for disinfection. In addition, we verified the high disinfecting performance of the water produced in an actual hospital.

  17. Microbes make average 2 nanometer diameter crystalline UO2 particles.

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kelly, S. D.; Kemner, K. M.; Banfield, J. F.

    2001-12-01

    It is well known that phylogenetically diverse groups of microorganisms are capable of catalyzing the reduction of highly soluble U(VI) to highly insoluble U(IV), which rapidly precipitates as uraninite (UO2). Because biological uraninite is highly insoluble, microbial uranyl reduction is being intensively studied as the basis for a cost-effective in-situ bioremediation strategy. Previous studies have described UO2 biomineralization products as amorphous or poorly crystalline. The objective of this study is to characterize the nanocrystalline uraninite in detail in order to determine the particle size, crystallinity, and size-related structural characteristics, and to examine the implications of these for reoxidation and transport. In this study, we obtained U-contaminated sediment and water from an inactive U mine and incubated them anaerobically with nutrients to stimulate reductive precipitation of UO2 by indigenous anaerobic bacteria, mainly Gram-positive spore-forming Desulfosporosinus and Clostridium spp. as revealed by RNA-based phylogenetic analysis. Desulfosporosinus sp. was isolated from the sediment and UO2 was precipitated by this isolate from a simple solution that contains only U and electron donors. We characterized UO2 formed in both of the experiments by high resolution-TEM (HRTEM) and X-ray absorption fine structure analysis (XAFS). The results from HRTEM showed that both the pure and the mixed cultures of microorganisms precipitated around 1.5 - 3 nm crystalline UO2 particles. Some particles as small as around 1 nm could be imaged. Rare particles around 10 nm in diameter were also present. Particles adhere to cells and form colloidal aggregates with low fractal dimension. In some cases, coarsening by oriented attachment on \\{111\\} is evident. Our preliminary results from XAFS for the incubated U-contaminated sample also indicated an average diameter of UO2 of 2 nm. In nanoparticles, the U-U distance obtained by XAFS was 0.373 nm, 0.012 nm

  18. Tailoring nanocrystalline diamond film properties

    DOEpatents

    Gruen, Dieter M [Downers Grove, IL; McCauley, Thomas G [Somerville, MA; Zhou, Dan [Orlando, FL; Krauss, Alan R [Naperville, IL

    2003-07-15

    A method for controlling the crystallite size and growth rate of plasma-deposited diamond films. A plasma is established at a pressure in excess of about 55 Torr with controlled concentrations of hydrogen up to about 98% by volume, of unsubstituted hydrocarbons up to about 3% by volume and an inert gas of one or more of the noble gases and nitrogen up to about 98% by volume. The volume ratio of inert gas to hydrogen is preferably maintained at greater than about 4, to deposit a diamond film on a suitable substrate. The diamond film is deposited with a predetermined crystallite size and at a predetermined growth rate.

  19. Metal release from stainless steel particles in vitro-influence of particle size.

    PubMed

    Midander, K; Pan, J; Wallinder, I Odnevall; Leygraf, C

    2007-01-01

    Human inhalation of airborne metallic particles is important for health risk assessment. To study interactions between metallic particles and the human body, metal release measurements of stainless steel powder particles were performed in two synthetic biological media simulating lung-like environments. Particle size and media strongly influence the metal release process. The release rate of Fe is enhanced compared with Cr and Ni. In artificial lysosomal fluid (ALF, pH 4.5), the accumulated amounts of released metal per particle loading increase drastically with decreasing particle size. The release rate of Fe per unit surface area increases with decreasing particle size. Compared with massive sheet metal, fine powder particles (<4 microm) show similar release rates of Cr and Ni, but a higher release rate of Fe. Release rates in Gamble's solution (pH 7.4), for all powders investigated, are significantly lower compared to ALF. No clear trend is seen related to particle size in Gamble's solution.

  20. Multi-Length Scale Tribology of Electrophoretically Deposited Nickel-Diamond Coatings

    NASA Astrophysics Data System (ADS)

    Awasthi, Shikha; Goel, Sneha; Pandey, Chandra Prabha; Balani, Kantesh

    2017-02-01

    Electrophoretically deposited (EPD) nickel and its composite coatings are widely used to enhance the life span of continuous ingot casting molds in the steel, aerospace and automotive industries. This article reports the effect of different concentrations of diamond particles (2.5-10 g/L) on the wear mechanism of EPD Ni. The distribution of diamond particles in the Ni matrix was observed using Voronoi tessellation. Variation in COF was observed by a fretting wear test to be 0.51 ± 0.07 for Ni, which decreases to 0.35 ± 0.03 for the Ni-diamond coatings. The wear volume of the coatings with 7.5 g/L concentration of diamond was observed to be a minimum (0.051 ± 0.02 × 10-3 mm3) compared with other composite coatings. Further, the micro-scratch testing of the coatings also exhibited a reduced COF (0.03-0.12) for 7.5 g/L diamond concentration compared with Ni (0.08-0.13). Higher wear resistance of the diamond-added coatings (optimum 7.5 g/L concentration) is due to the balance between the dispersion strengthening mechanism and the enhancement of the load-bearing capacity due to the incorporation of diamond particles. Thus, these composites can be used for applications in automotive and aerospace industries.

  1. Charge multiplication effect in thin diamond films

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

    Skukan, N., E-mail: nskukan@irb.hr; Grilj, V.; Sudić, I.

    2016-07-25

    Herein, we report on the enhanced sensitivity for the detection of charged particles in single crystal chemical vapour deposition (scCVD) diamond radiation detectors. The experimental results demonstrate charge multiplication in thin planar diamond membrane detectors, upon impact of 18 MeV O ions, under high electric field conditions. Avalanche multiplication is widely exploited in devices such as avalanche photo diodes, but has never before been reproducibly observed in intrinsic CVD diamond. Because enhanced sensitivity for charged particle detection is obtained for short charge drift lengths without dark counts, this effect could be further exploited in the development of sensors based on avalanchemore » multiplication and radiation detectors with extreme radiation hardness.« less

  2. Improvement of diamond-like carbon electrochemical corrosion resistance by addition of nanocrystalline diamond.

    PubMed

    Marciano, F R; Almeida, E C; Bonetti, L F; Corat, E J; Trava-Airoldi, V J

    2010-02-15

    Nanocrystalline diamond (NCD) particles were incorporated into diamond-like carbon (DLC) films in order to investigate NCD-DLC electrochemical corrosion resistance. The films were grown over 304 stainless steel using plasma-enhanced chemical vapor deposition. NCD particles were incorporated into DLC during the deposition process. The investigation of NCD-DLC electrochemical corrosion behavior was performed using potentiodynamic polarization against NaCl. NCD-DLC films presented more negative corrosion potential and lower anodic and cathodic current densities. The electrochemical analysis indicated that NCD-DLC films present superior impedance and polarization resistance compared to the pure DLC, which indicate that they are promising corrosion protective coatings in aggressive solutions. Copyright 2009 Elsevier Inc. All rights reserved.

  3. Recent trends in particle size analysis techniques

    NASA Technical Reports Server (NTRS)

    Kang, S. H.

    1984-01-01

    Recent advances and developments in the particle-sizing technologies are briefly reviewed in accordance with three operating principles including particle size and shape descriptions. Significant trends of the particle size analysing equipment recently developed show that compact electronic circuitry and rapid data processing systems were mainly adopted in the instrument design. Some newly developed techniques characterizing the particulate system were also introduced.

  4. Characterization of fine abrasive particles for optical fabrication

    NASA Astrophysics Data System (ADS)

    Funkenbusch, Paul D.; Zhou, Y. Y.; Takahashi, Toshio; Quesnel, David J.; Lambropoulos, John C.

    1995-08-01

    Material removal during fine grinding operations is accomplished primarily by the action of individual abrasive particles on the glass surface. The mechanical properties of the abrasive are therefore important. Unfortunately it is difficult to directly measure the mechanical response of abrasives once they reach the scale of approximately 10 microns. As a result mechanical properties of fine abrasives are sometimes characterized in terms of an empirical `friability', based on the response of the abrasive to crushing by a metal ball in a vial. In this paper we report on modeling/experiments designed to more precisely quantify the mechanical properties of fine abrasives and ultimately to relate them to the conditions experienced by bound particles during grinding. Experiments have been performed on various types and sizes of diamond abrasives. The response of the particles is a strong function of the loading conditions and can be tracked by changing the testing parameters. Diamond size is also found to play a critical role, with finer diamonds less susceptible to fracture. A micromechanical model from the literature is employed estimate the forces likely to be seen during testing. We are also developing dynamic models to better predict the forces experienced during `friability' testing as a function of the testing parameters.

  5. Oxidation-induced structural changes in sub-nanometer platinum supported on alumina

    DOE PAGES

    DeBusk, Melanie Moses; Allard, Jr, Lawrence Frederick; Blom, Douglas Allen; ...

    2015-06-26

    Platinum supported on alumina is an essential component of emission treatment catalysts used in transportation. Theoretical, experimental, and mechanistic aspects of platinum particles supported on a variety of supports have been extensively studied; however, available experimental information on the behavior of single vs. sub-nanometer platinum is extremely limited. To bridge the knowledge gap between single supported platinum and well-formed supported platinum nanoparticles, we have carried out synthesis, characterization, and CO and NO oxidation studies of sub-nanometer platinum supported on α, θ, and γ-Al 2O 3 and monitored changes in structure upon exposure to CO and NO oxidation conditions. Furthermore, wemore » find that sub-nanometer Pt is highly effective for CO oxidation due to high platinum dispersion but is not very efficient as NO oxidation catalyst. Lastly, sub-nanometer platinum agglomerates rapidly under CO or NO oxidation conditions to form nanoparticles.« less

  6. Random deposition of particles of different sizes.

    PubMed

    Forgerini, F L; Figueiredo, W

    2009-04-01

    We study the surface growth generated by the random deposition of particles of different sizes. A model is proposed where the particles are aggregated on an initially flat surface, giving rise to a rough interface and a porous bulk. By using Monte Carlo simulations, a surface has grown by adding particles of different sizes, as well as identical particles on the substrate in (1+1) dimensions. In the case of deposition of particles of different sizes, they are selected from a Poisson distribution, where the particle sizes may vary by 1 order of magnitude. For the deposition of identical particles, only particles which are larger than one lattice parameter of the substrate are considered. We calculate the usual scaling exponents: the roughness, growth, and dynamic exponents alpha, beta, and z, respectively, as well as, the porosity in the bulk, determining the porosity as a function of the particle size. The results of our simulations show that the roughness evolves in time following three different behaviors. The roughness in the initial times behaves as in the random deposition model. At intermediate times, the surface roughness grows slowly and finally, at long times, it enters into the saturation regime. The bulk formed by depositing large particles reveals a porosity that increases very fast at the initial times and also reaches a saturation value. Excepting the case where particles have the size of one lattice spacing, we always find that the surface roughness and porosity reach limiting values at long times. Surprisingly, we find that the scaling exponents are the same as those predicted by the Villain-Lai-Das Sarma equation.

  7. Tracing temperature in a nanometer size region in a picosecond time period.

    PubMed

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-08-21

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model.

  8. Constraining ejecta particle size distributions with light scattering

    NASA Astrophysics Data System (ADS)

    Schauer, Martin; Buttler, William; Frayer, Daniel; Grover, Michael; Lalone, Brandon; Monfared, Shabnam; Sorenson, Daniel; Stevens, Gerald; Turley, William

    2017-06-01

    The angular distribution of the intensity of light scattered from a particle is strongly dependent on the particle size and can be calculated using the Mie solution to Maxwell's equations. For a collection of particles with a range of sizes, the angular intensity distribution will be the sum of the contributions from each particle size weighted by the number of particles in that size bin. The set of equations describing this pattern is not uniquely invertible, i.e. a number of different distributions can lead to the same scattering pattern, but with reasonable assumptions about the distribution it is possible to constrain the problem and extract estimates of the particle sizes from a measured scattering pattern. We report here on experiments using particles ejected by shockwaves incident on strips of triangular perturbations machined into the surface of tin targets. These measurements indicate a bimodal distribution of ejected particle sizes with relatively large particles (median radius 2-4 μm) evolved from the edges of the perturbation strip and smaller particles (median radius 200-600 nm) from the perturbations. We will briefly discuss the implications of these results and outline future plans.

  9. Carbon Nanotubules: Building Blocks for Nanometer-Scale Engineering

    NASA Technical Reports Server (NTRS)

    Sinnott, Susan B.

    1997-01-01

    Proximal probe technology has provided researchers with new ways to investigate and manipulate matter on the nanometer scale. We have studied, through molecular dynamics simulations, using a many-body empirical potential, the indentation of a hydrogen-terminated, diamond (111 ) surface, with a proximal probe tip that consists of an open, hydrogen-terminated, (10,10) carbon nanotubule. The simulations showed that upon indenting 1.8 A, the tubule deforms but returns to its original shape upon retraction. The Young's modulus of the tubule was determined using the predicted Euler buckling force and was found to be comparable to measured and calculated values. In a second series of simulations, an open (10, 10) nanotubule was heated to 4500 K and allowed to close. We find that at this temperature the resulting cap contains numerous imperfections, including some not mentioned previously in the literature.

  10. Nanocrystalline diamond micro-anvil grown on single crystal diamond as a generator of ultra-high pressures

    DOE PAGES

    Samudrala, Gopi K.; Moore, Samuel L.; Velisavljevic, Nenad; ...

    2016-09-29

    By combining mask-less lithography and chemical vapor deposition (CVD) techniques, a novel two-stage diamond anvil has been fabricated. A nanocrystalline diamond (NCD) micro-anvil 30 μm in diameter was grown at the center of a [100]-oriented, diamond anvil by utilizing microwave plasma CVD method. The NCD micro-anvil has a diamond grain size of 115 nm and micro-focused Raman and X-ray Photoelectron spectroscopy analysis indicate sp3-bonded diamond content of 72%. Lastly, these CVD grown NCD micro-anvils were tested in an opposed anvil configuration and the transition metals osmium and tungsten were compressed to high pressures of 264 GPa in a diamond anvilmore » cell.« less

  11. Fabrications of insulator-protected nanometer-sized electrode gaps

    NASA Astrophysics Data System (ADS)

    Arima, Akihide; Tsutsui, Makusu; Morikawa, Takanori; Yokota, Kazumichi; Taniguchi, Masateru

    2014-03-01

    We developed SiO2-coated mechanically controllable break junctions for accurate tunneling current measurements in an ionic solution. By breaking the junction, we created dielectric-protected Au nanoprobes with nanometer separation. We demonstrated that the insulator protection was capable to suppress the ionic contribution to the charge transport through the electrode gap, thereby enabled reliable characterizations of liquid-mediated exponential decay of the tunneling conductance in an electrolyte solution. From this, we found distinct roles of charge points such as molecular dipoles and ion species on the tunneling decay constant, which was attributed to local structures of molecules and ions in the confined space between the sensing electrodes. The device described here would provide improved biomolecular sensing capability of tunneling current sensors.

  12. Microinclusions in polycrystalline diamonds: insights into processes of diamond formation

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Wirth, R.; Enzmann, F.; Schwarz, J. O.; Kronz, A.

    2009-04-01

    Polycrystalline diamond aggregates (framesites) contain silicates of eclogitic and peridotitic affinity (e.g. Kurat and Dobosi, 2000). The minerals occur mostly in interstices and are intimately intergrown with the diamonds, indicating contemporaneous crystallization within the diamond stability field in the Earth's mantle. In addition to silicates, rarer phases such as Fe-carbide can sometimes be found in framesites that record unusually low local oxygen fugacity at the time of their formation (Jacob et al., 2004). Furthermore, while most gem-sized diamonds have old, often Archaean formation ages, some polycrystalline diamond aggregates have been shown to form directly preceding the kimberlite eruption (Jacob et al., 2000). Thus, these samples may provide a unique source of information on the nature and timing of small scale processes that lead to diamond formation and complement evidence from gem-sized diamonds. Here, we present a study of micro- and nano-inclusions in diamonds from a polycrystalline diamond aggregate (framesite) from the Orapa Mine (Botswana) and combine results from TEM/FIB analyses with high-resolution computerized micro-tomography (HR-µCT) and electron microprobe analyses to further constrain the formation of diamond in the Earth's mantle. Results In total, 14 microinclusions from fifteen FIB foils were investigated. Micro- and nano-inclusions identified by TEM were smaller than 1µm down to ca. 50nm in size, and are both monomineralic and multi-phase. The cavities are often lath-shaped and oriented parallel to each other; many show lattice dislocations in the surrounding diamond. In addition, inclusions are found along open cracks within the diamond single crystals. Mineral phases in the microinclusions comprise rutile, omphacite and a FeS phase (pyrrhotite). The multiphase inclusions most often consist of cavities that are only partly occupied (less than 50% of the total space), suggesting that the empty space was originally filled by a

  13. Lipoproteins: When size really matters

    PubMed Central

    German, J. Bruce; Smilowitz, Jennifer T.; Zivkovic, Angela M.

    2010-01-01

    The field of nanoscience is extending the applications of physics, chemistry and biology into previously unapproached infinitesimal length scales. Understanding the behavior and manipulating the positions and properties of single atoms and molecules hold great potential to improve areas of science as disparate as medicine and computation, and communication and orbiting satellites. Yet, in the race to develop novel, previously unavailable nanoparticles, there is an opportunity for scientists in this field to digress and to apply their growing understanding of nanoscience and the tools of nanotechnology to one of the most pressing problems in all of human biology—diseases related to lipoproteins. Although not appreciated outside the field of lipoprotein biology, variations in the compositions, structures and properties of these nanoscale-sized, blood-borne particles are responsible for most of the variations in health, morbidity and mortality in the Western world. If the lipoproteins could be understood at the nanometer length scale with precise details of their structures and functions, scientists could understand a wide range of perplexing physiological processes and also address the dysfunctions in normal lipoprotein biology that lead to such diseases as hypercholesterolemia, heart disease, stroke and neurodegenerative diseases. Furthermore, if the capabilities of nanoscience to assemble and manipulate nanometer-sized particles could be recruited to studies of lipoproteins, these biological particles would provide a new dimension to therapeutic agents, and these natural particles could be designed to carry out many specialized beneficial tasks. PMID:20592953

  14. Solution nuclear magnetic resonance spectroscopy on a nanostructured diamond chip.

    PubMed

    Kehayias, P; Jarmola, A; Mosavian, N; Fescenko, I; Benito, F M; Laraoui, A; Smits, J; Bougas, L; Budker, D; Neumann, A; Brueck, S R J; Acosta, V M

    2017-08-04

    Sensors using nitrogen-vacancy centers in diamond are a promising tool for small-volume nuclear magnetic resonance (NMR) spectroscopy, but the limited sensitivity remains a challenge. Here we show nearly two orders of magnitude improvement in concentration sensitivity over previous nitrogen-vacancy and picoliter NMR studies. We demonstrate NMR spectroscopy of picoliter-volume solutions using a nanostructured diamond chip with dense, high-aspect-ratio nanogratings, enhancing the surface area by 15 times. The nanograting sidewalls are doped with nitrogen-vacancies located a few nanometers from the diamond surface to detect the NMR spectrum of roughly 1 pl of fluid lying within adjacent nanograting grooves. We perform 1 H and 19 F nuclear magnetic resonance spectroscopy at room temperature in magnetic fields below 50 mT. Using a solution of CsF in glycerol, we determine that 4 ± 2 × 10 12 19 F spins in a 1 pl volume can be detected with a signal-to-noise ratio of 3 in 1 s of integration.Nitrogen vacancy (NV) centres in diamond can be used for NMR spectroscopy, but increased sensitivity is needed to avoid long measurement times. Kehayias et al. present a nanostructured diamond grating with a high density of NV centres, enabling NMR spectroscopy of picoliter-volume solutions.

  15. Frequency-scanning particle size spectrometer

    NASA Technical Reports Server (NTRS)

    Fymat, A. L. (Inventor)

    1979-01-01

    A particle size spectrometer having a fixed field of view within the forward light scattering cone at an angle theta sub s between approximately 100 and 200 minutes of arc (preferably at 150 minutes), a spectral range extending approximately from 0.2 to 4.0 inverse micrometers, and a spectral resolution between about 0.1 and 0.2 inverse micrometers (preferably toward the lower end of this range of spectral resolution), is employed to determine the distribution of particle sizes, independently of the chemical composition of the particles, from measurements of incident light, at each frequency, sigma (=1/lambda), and scattered light, I(sigma).

  16. Particle Size Effects on CL-20 Initiation and Detonation

    NASA Astrophysics Data System (ADS)

    Valancius, Cole; Bainbridge, Joe; Love, Cody; Richardson, Duane

    2017-06-01

    Particle size or specific surface area effects on explosives has been of interest to the explosives community for both application and modeling of initiation and detonation. Different particles sizes of CL-20 were used in detonator experiments to determine the effects of particle size on initiation, run-up to steady state detonation, and steady state detonation. Historical tests have demonstrated a direct relationship between particle size and initiation. However, historical tests inadvertently employed density gradients, making it difficult to discern the effects of particle size from the effects of density. Density gradients were removed from these tests using a larger diameter, shorter charge column, allowing for similar loading across different particle sizes. Without the density gradient, the effects of particle size on initiation and detonation are easier to determine. The results of which contrast with historical results, showing particle size does not directly affect initiation threshold.

  17. Electron energy loss spectrometry of interstellar diamonds

    NASA Technical Reports Server (NTRS)

    Bernatowicz, Thomas J.; Gibbons, Patrick C.; Lewis, Roy S.

    1990-01-01

    The results are reported of electron energy loss spectra (EELS) measurements on diamond residues from carbonaceous meteorites designed to elucidate the structure and composition of interstellar diamonds. Dynamic effective medium theory is used to model the dielectric properties of the diamonds and in particular to synthesize the observed spectra as mixtures of diamond and various pi-bonded carbons. The results are shown to be quantitatively consistent with the idea that diamonds and their surfaces are the only contributors to the electron energy loss spectra of the diamond residues and that these peculiar spectra are the result of the exceptionally small grain size and large specific surface area of the interstellar diamonds.

  18. Method of producing non-agglomerating submicron size particles

    DOEpatents

    Bourne, Roy S.; Eichman, Clarence C.; Welbon, William W.

    1989-01-01

    Submicron size particles are produced by using a sputtering process to deposit particles into a liquid. The liquid is processed to recover the particles therefrom, and the particles have sizes in the range of twenty to two hundred Angstroms. Either metallic or non-metallic particles can be produced, and the metallic particles can be used in "metallic inks".

  19. Size and diluted magnetic properties of diamond shaped graphene quantum dots: Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Masrour, R.; Jabar, A.

    2018-05-01

    The magnetic properties of diamond shaped graphene quantum dots have been investigated by varying their sizes with the Monte Carlo simulation. The magnetizations and magnetic susceptibilities have been studied with dilutions x (magnetic atom), several sizes L (carbon atom) and exchange interaction J between the magnetic atoms. The all magnetic susceptibilities have been situated at the transitions temperatures of each parameters. The obtained values increase when increases the values of x, L and J. The effect of exchanges interactions and crystal field on the magnetization has been discussed. The magnetic hysteresis cycles for several dilutions x, sizes L, exchange interactions J and temperatures T. The magnetic coercive increases with increasing the exchange interactions and decreases when the temperatures values increasing.

  20. Computational Study of Field Initiated Surface Reactions for Synthesis of Diamond and Silicon

    NASA Technical Reports Server (NTRS)

    Musgrave, Charles Bruce

    1999-01-01

    This project involves using quantum chemistry to simulate surface chemical reactions in the presence of an electric field for nanofabrication of diamond and silicon. A field delivered by a scanning tunneling microscope (STM) to a nanometer scale region of a surface affects chemical reaction potential energy surfaces (PES) to direct atomic scale surface modification to fabricate sub-nanometer structures. Our original hypothesis is that the applied voltage polarizes the charge distribution of the valence electrons and that these distorted molecular orbitals can be manipulated with the STM so as to change the relative stabilities of the electronic configurations over the reaction coordinates and thus the topology of the PES and reaction kinetics. Our objective is to investigate the effect of applied bias on surface reactions and the extent to which STM delivered fields can be used to direct surface chemical reactions on an atomic scale on diamond and silicon. To analyze the fundamentals of field induced chemistry and to investigate the application of this technique for the fabrication of nanostructures, we have employed methods capable of accurately describing molecular electronic structure. The methods we employ are density functional theory (DFT) quantum chemical (QC) methods. To determine the effect of applied bias on surface reactions we have calculated the QC PESs in various applied external fields for various reaction steps for depositing or etching diamond and silicon. We have chosen reactions which are thought to play a role in etching and the chemical vapor deposition growth of Si and diamond. The PESs of the elementary reaction steps involved are then calculated under the applied fields, which we vary in magnitude and configuration. We pay special attention to the change in the reaction barriers, and transition state locations, and search for low energy reaction channels which were inaccessible without the applied bias.

  1. ELECTROSTATIC CHARGE ON NANO-PARTICLES ACTIVATES CNS MACROPHAGES (MICROGLIA).

    EPA Science Inventory

    Nanometer size particles carry free radical activity on their surface and can produce oxidative stress (OS)-mediated damage upon impact to target cells. The initiating event of phage cell activation (i.e., the oxidative burst) is unknown, although many proximal events have been i...

  2. Friction and Wear Properties of As-deposited and Carbon Ion-implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1994-01-01

    -grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum. The wear mechanism of diamond films is that of small fragments chipping off the surface. The size of wear particles is related to the extent of wear rates.

  3. Diamonds in ophiolites: Contamination or a new diamond growth environment?

    NASA Astrophysics Data System (ADS)

    Howell, D.; Griffin, W. L.; Yang, J.; Gain, S.; Stern, R. A.; Huang, J.-X.; Jacob, D. E.; Xu, X.; Stokes, A. J.; O'Reilly, S. Y.; Pearson, N. J.

    2015-11-01

    For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative δ13C values are present in both sets of diamonds. The Tibetan diamonds (n = 3) show an exceptionally large range in δ15N (-5.6 to + 28.7 ‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with δ15N = 0 ‰ in {111} sectors and + 30 ‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The

  4. Tailoring nanocrystalline diamond coated on titanium for osteoblast adhesion.

    PubMed

    Pareta, Rajesh; Yang, Lei; Kothari, Abhishek; Sirinrath, Sirivisoot; Xiao, Xingcheng; Sheldon, Brian W; Webster, Thomas J

    2010-10-01

    Diamond coatings with superior chemical stability, antiwear, and cytocompatibility properties have been considered for lengthening the lifetime of metallic orthopedic implants for over a decade. In this study, an attempt to tailor the surface properties of diamond films on titanium to promote osteoblast (bone forming cell) adhesion was reported. The surface properties investigated here included the size of diamond surface features, topography, wettability, and surface chemistry, all of which were controlled during microwave plasma enhanced chemical-vapor-deposition (MPCVD) processes using CH4-Ar-H2 gas mixtures. The hardness and elastic modulus of the diamond films were also determined. H2 concentration in the plasma was altered to control the crystallinity, grain size, and topography of the diamond coatings, and specific plasma gases (O2 and NH3) were introduced to change the surface chemistry of the diamond coatings. To understand the impact of the altered surface properties on osteoblast responses, cell adhesion tests were performed on the various diamond-coated titanium. The results revealed that nanocrystalline diamond (grain sizes <100 nm) coated titanium dramatically increased surface hardness, and the introduction of O2 and NH3 during the MPCVD process promoted osteoblast adhesion on diamond and, thus, should be further studied for improving orthopedic applications. Copyright 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

  5. Laser Transmission Measurements and Plume Particle Size Distributions for Propellant Burn Tests at ATK Elkton in May 2012

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

    Willitsford, Adam H.; Brown, David M.; Brown, Andrea M.

    2014-08-28

    Multi-wavelength laser transmittance was measured during a series of open-air propellant burn tests at Alliant Techsystems, Inc., in Elkton, MD, in May 2012. A Mie scattering model was combined with an alumina optical properties model in a simple single-scatter approach to fitting plume transmittance. Wavelength-dependent plume transmission curves were fit to the measured multi-wave- length transmittance data to infer plume particle size distributions at several heights in the plume. Tri-modal lognormal distributions described transmittance data well at all heights. Overall distributions included a mode with nanometer-scale diameter, a second mode at a diameter of ~0.5 µm, and a third, largermore » particle mode. Larger parti- cles measured 2.5 µm in diameter at 34 cm (14 in.) above the burning propellant surface, but grew to 4 µm in diameter at a height of 57 cm (22 in.), indicative of particle agglomeration in progress as the plume rises. This report presents data, analysis, and results from the study.« less

  6. Size Effect on Specific Energy Distribution in Particle Comminution

    NASA Astrophysics Data System (ADS)

    Xu, Yongfu; Wang, Yidong

    A theoretical study is made to derive an energy distribution equation for the size reduction process from the fractal model for the particle comminution. Fractal model is employed as a valid measure of the self-similar size distribution of comminution daughter products. The tensile strength of particles varies with particle size in the manner of a power function law. The energy consumption for comminuting single particle is found to be proportional to the 5(D-3)/3rd order of the particle size, D being the fractal dimension of particle comminution daughter. The Weibull statistics is applied to describe the relationship between the breakage probability and specific energy of particle comminution. A simple equation is derived for the breakage probability of particles in view of the dependence of fracture energy on particle size. The calculated exponents and Weibull coefficients are generally in conformity with published data for fracture of particles.

  7. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering.

    PubMed

    Makan, Ashwell C; Spallek, Markus J; du Toit, Madeleine; Klein, Thorsten; Pasch, Harald

    2016-04-15

    Field flow fractionation (FFF) is an advanced fractionation technique for the analyses of very sensitive particles. In this study, different FFF techniques were used for the fractionation and analysis of polymer emulsions/latexes. As model systems, a pure acrylic emulsion and emulsions containing titanium dioxide were prepared and analyzed. An acrylic emulsion polymerization was conducted, continuously sampled from the reactor and subsequently analyzed to determine the particle size, radius of gyration in specific, of the latex particles throughout the polymerization reaction. Asymmetrical flow field-flow fractionation (AF4) and sedimentation field-flow fractionation (SdFFF), coupled to a multidetector system, multi-angle laser light scattering (MALLS), ultraviolet (UV) and refractive index (RI), respectively, were used to investigate the evolution of particle sizes and particle size distributions (PSDs) as the polymerization progressed. The obtained particle sizes were compared against batch-mode dynamic light scattering (DLS). Results indicated differences between AF4 and DLS results due to DLS taking hydration layers into account, whereas both AF4 and SdFFF were coupled to MALLS detection, hence not taking the hydration layer into account for size determination. SdFFF has additional separation capabilities with a much higher resolution compared to AF4. The calculated radii values were 5 nm larger for SdFFF measurements for each analyzed sample against the corresponding AF4 values. Additionally a low particle size shoulder was observed for SdFFF indicating bimodality in the reactor very early during the polymerization reaction. Furthermore, different emulsions were mixed with inorganic species used as additives in cosmetics and coatings such as TiO2. These complex mixtures of species were analyzed to investigate the retention and particle interaction behavior under different AF4 experimental conditions, such as the mobile phase. The AF4 system was coupled online

  8. Thermal and ultrasonic influence in the formation of nanometer scale hydroxyapatite bio-ceramic

    PubMed Central

    Poinern, GJE; Brundavanam, R; Le, X Thi; Djordjevic, S; Prokic, M; Fawcett, D

    2011-01-01

    Hydroxyapatite (HAP) is a widely used biocompatible ceramic in many biomedical applications and devices. Currently nanometer-scale forms of HAP are being intensely investigated due to their close similarity to the inorganic mineral component of the natural bone matrix. In this study nano-HAP was prepared via a wet precipitation method using Ca(NO3)2 and KH2PO4 as the main reactants and NH4OH as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH was maintained at 9 during the synthesis process. The influence of the thermal treatment was investigated by using two thermal treatment processes to produce ultrafine nano-HAP powders. In the first heat treatment, a conventional radiant tube furnace was used to produce nano-particles with an average size of approximately 30 nm in diameter, while the second thermal treatment used a microwave-based technique to produce particles with an average diameter of 36 nm. The crystalline structure and morphology of all nanoparticle powders produced were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Both thermal techniques effectively produced ultrafine powders with similar crystalline structure, morphology and particle sizes. PMID:22114473

  9. Ejected Particle Size Distributions from Shocked Metal Surfaces

    DOE PAGES

    Schauer, M. M.; Buttler, W. T.; Frayer, D. K.; ...

    2017-04-12

    Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

  10. Ejected Particle Size Distributions from Shocked Metal Surfaces

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

    Schauer, M. M.; Buttler, W. T.; Frayer, D. K.

    Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

  11. Bose-Einstein condensation in diamond hierarchical lattices.

    PubMed

    Lyra, M L; de Moura, F A B F; de Oliveira, I N; Serva, M

    2014-05-01

    The Bose-Einstein condensation of noninteracting particles restricted to move on the sites of hierarchical diamond lattices is investigated. Using a tight-binding single-particle Hamiltonian with properly rescaled hopping amplitudes, we are able to employ an orthogonal basis transformation to exactly map it on a set of decoupled linear chains with sizes and degeneracies written in terms of the network branching parameter q and generation number n. The integrated density of states is shown to have a fractal structure of gaps and degeneracies with a power-law decay at the band bottom. The spectral dimension d(s) coincides with the network topological dimension d(f) = ln(2q)/ln(2). We perform a finite-size scaling analysis of the fraction of condensed particles and specific heat to characterize the critical behavior of the BEC transition that occurs for q > 2 (d(s) > 2). The critical exponents are shown to follow those for lattices with a pure power-law spectral density, with non-mean-field values for q < 8 (d(s) < 4). The transition temperature is shown to grow monotonically with the branching parameter, obeying the relation 1/T(c) = a + b/(q - 2).

  12. Changes in the mechanism of heat transfer in passing from microparticles to nanoparticles

    NASA Astrophysics Data System (ADS)

    Shakhov, F. M.; Meilakhs, A. P.; Eidelman, E. D.

    2016-03-01

    On the basis of experimental data on thermal conduction and sound velocity in composites obtained by sintering detonation nanodiamonds with the crystallite size of 4-5 nm and diamond micropowders with a grain size of about 10 μm at a high pressure (5-7 GPa) and high temperature (1200-1800°C), mechanisms of heat transfer in such structures are suggested. These mechanisms are shown to be different in composites of micro- and nanoparticles. In composites of micrometer particles, the conventional macroscopic mechanism of phonon propagation is active. In composites with a grain size of a few nanometers, the main contribution comes from thermal resistance on grain boundaries.

  13. Effect of titanium addition on the thermal properties of diamond/cu-ti composites fabricated by pressureless liquid-phase sintering technique.

    PubMed

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m · K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained.

  14. Patterning of nanocrystalline diamond films for diamond microstructures useful in MEMS and other devices

    DOEpatents

    Gruen, Dieter M [Downers Grove, IL; Busmann, Hans-Gerd [Bremen, DE; Meyer, Eva-Maria [Bremen, DE; Auciello, Orlando [Bolingbrook, IL; Krauss, Alan R [late of Naperville, IL; Krauss, Julie R [Naperville, IL

    2004-11-02

    MEMS structure and a method of fabricating them from ultrananocrystalline diamond films having average grain sizes of less than about 10 nm and feature resolution of less than about one micron . The MEMS structures are made by contacting carbon dimer species with an oxide substrate forming a carbide layer on the surface onto which ultrananocrystalline diamond having average grain sizes of less than about 10 nm is deposited. Thereafter, microfabrication process are used to form a structure of predetermined shape having a feature resolution of less than about one micron.

  15. Sheathless Size-Based Acoustic Particle Separation

    PubMed Central

    Guldiken, Rasim; Jo, Myeong Chan; Gallant, Nathan D.; Demirci, Utkan; Zhe, Jiang

    2012-01-01

    Particle separation is of great interest in many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In this paper, we present a microfluidic platform for sheathless particle separation using standing surface acoustic waves. In this platform, particles are first lined up at the center of the channel without introducing any external sheath flow. The particles are then entered into the second stage where particles are driven towards the off-center pressure nodes for size based separation. The larger particles are exposed to more lateral displacement in the channel due to the acoustic force differences. Consequently, different-size particles are separated into multiple collection outlets. The prominent feature of the present microfluidic platform is that the device does not require the use of the sheath flow for positioning and aligning of particles. Instead, the sheathless flow focusing and separation are integrated within a single microfluidic device and accomplished simultaneously. In this paper, we demonstrated two different particle size-resolution separations; (1) 3 μm and 10 μm and (2) 3 μm and 5 μm. Also, the effects of the input power, the flow rate, and particle concentration on the separation efficiency were investigated. These technologies have potential to impact broadly various areas including the essential microfluidic components for lab-on-a-chip system and integrated biological and biomedical applications. PMID:22368502

  16. Ultraviolet (UV) disinfection of grey water: particle size effects.

    PubMed

    Winward, G P; Avery, L M; Stephenson, T; Jefferson, B

    2008-02-01

    The impact of water quality on the ultraviolet (UV) disinfection of grey water was investigated with reference to urban water reuse. Direct UV disinfection of grey water did not meet the stringent California State Title 22 criteria for unrestricted urban water reuse due to the presence of particulate material ranging from < 1 to > or = 2000 microm in size. Grey water was manipulated by settling to produce fractions of varying particle size distributions and blending was employed post-disinfection to extract particle-associated coliforms (PACs). The efficacy of UV disinfection was found to be linked to the particle size of the grey water fractions. The larger particle size fractions with a mean particle size of 262 microm and above were observed to shield more coliforms from UV light than did the smaller particles with a mean particle size below 119 microm. Up to 70% of total coliforms in the larger particle size fractions were particle-associated following a UV dose (fluence) of 260 mJ.cm(-2) and would remain undetected by standard coliform enumeration techniques. Implications for urban water reuse are discussed and recommendations made for grey water treatment to ensure removal of particle-associated indicator bacteria and pathogens prior to UV disinfection.

  17. Calibration of optical particle-size analyzer

    DOEpatents

    Pechin, William H.; Thacker, Louis H.; Turner, Lloyd J.

    1979-01-01

    This invention relates to a system for the calibration of an optical particle-size analyzer of the light-intercepting type for spherical particles, wherein a rotary wheel or disc is provided with radially-extending wires of differing diameters, each wire corresponding to a particular equivalent spherical particle diameter. These wires are passed at an appropriate frequency between the light source and the light detector of the analyzer. The reduction of light as received at the detector is a measure of the size of the wire, and the electronic signal may then be adjusted to provide the desired signal for corresponding spherical particles. This calibrator may be operated at any time without interrupting other processing.

  18. Vertically aligned nanowires from boron-doped diamond.

    PubMed

    Yang, Nianjun; Uetsuka, Hiroshi; Osawa, Eiji; Nebel, Christoph E

    2008-11-01

    Vertically aligned diamond nanowires with controlled geometrical properties like length and distance between wires were fabricated by use of nanodiamond particles as a hard mask and by use of reactive ion etching. The surface structure, electronic properties, and electrochemical functionalization of diamond nanowires were characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) as well as electrochemical techniques. AFM and STM experiments show that diamond nanowire etched for 10 s have wire-typed structures with 3-10 nm in length and with typically 11 nm spacing in between. The electrode active area of diamond nanowires is enhanced by a factor of 2. The functionalization of nanowire tips with nitrophenyl molecules is characterized by STM on clean and on nitrophenyl molecule-modified diamond nanowires. Tip-modified diamond nanowires are promising with respect to biosensor applications where controlled biomolecule bonding is required to improve chemical stability and sensing significantly.

  19. Reduction of glycine particle size by impinging jet crystallization.

    PubMed

    Tari, Tímea; Fekete, Zoltán; Szabó-Révész, Piroska; Aigner, Zoltán

    2015-01-15

    The parameters of crystallization processes determine the habit and particle size distribution of the products. A narrow particle size distribution and a small average particle size are crucial for the bioavailability of poorly water-soluble pharmacons. Thus, particle size reduction is often required during crystallization processes. Impinging jet crystallization is a method that results in a product with a reduced particle size due to the homogeneous and high degree of supersaturation at the impingement point. In this work, the applicability of the impinging jet technique as a new approach in crystallization was investigated for the antisolvent crystallization of glycine. A factorial design was applied to choose the relevant crystallization factors. The results were analysed by means of a statistical program. The particle size distribution of the crystallized products was investigated with a laser diffraction particle size analyser. The roundness and morphology were determined with the use of a light microscopic image analysis system and a scanning electron microscope. Polymorphism was characterized by differential scanning calorimetry and powder X-ray diffraction. Headspace gas chromatography was utilized to determine the residual solvent content. Impinging jet crystallization proved to reduce the particle size of glycine. The particle size distribution was appropriate, and the average particle size was an order of magnitude smaller (d(0.5)=8-35 μm) than that achieved with conventional crystallization (d(0.5)=82-680 μm). The polymorphic forms of the products were influenced by the solvent ratio. The quantity of residual solvent in the crystallized products was in compliance with the requirements of the International Conference on Harmonization. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Towards High Density 3-D Memory in Diamond

    NASA Astrophysics Data System (ADS)

    Henshaw, Jacob; Dhomkar, Siddharth; Meriles, Carlos; Jayakumar, Harishankar

    The nitrogen-vacancy (NV) center in diamond is presently the focus of widespread attention for applications ranging from quantum information processing to nanoscale metrology. Of great utility is the ability to optically initialize the NV charge state, which has an immediate impact on the center's light emission properties. Here, we use two-color microscopy in NV-rich, type-1b diamond to demonstrate fluorescence-encoded long-term storage of classical information. As a proof of principle, we write, reset, and rewrite various patterns with 2-D binary bit density comparable to present DVD-ROM technology. The strong fluorescence signal originating from the diffraction-limited bit volume allows us to transition from binary to multi-valued encoding, which translates into a significant storage capacity boost. Finally, we show that our technique preserves information written on different planes of the diamond crystal and thus serves as a platform for three-dimensional storage. Substantial enhancement in the bit density could be achieved with the aid of super resolution microscopy techniques already employed to discriminate between NVs with sub-diffraction, nanometer accuracy, a regime where the storage capacity could exceed 1017 bytes/cm3 We acknowledge support from the National Science Foundation through Grant NSF-1314205.

  1. Nanodiamonds: Their Structure and Optical Properties

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

    Raty, J.-Y.; van Buuren, T.; Galli, G.

    2002-05-14

    Nanometer sized diamond is a constituent of diverse systems ranging from interstellar dusts and meteorites [1] to carbonaceous residues of detonations [2] and diamond-like films [3-5]. Many of the properties of bulk diamond have been well understood for decades, those of nanodiamond are mostly unexplored. We present a combined theoretical and experimental study showing that diamond has unique properties not only as a bulk material but also at the nanoscale, where size reduction and surface reconstruction effects are fundamentally different from those found, e.g. in Si and Ge.

  2. The Effect of Particle Size on the Biodistribution of Low-modulus Hydrogel PRINT Particles

    PubMed Central

    Merkel, Timothy J.; Chen, Kai; Jones, Stephen W.; Pandya, Ashish A.; Tian, Shaomin; Napier, Mary E.; Zamboni, William E.; DeSimone, Joseph M.

    2012-01-01

    There is a growing recognition that the deformability of particles used for drug delivery plays a significant role on their biodistribution and circulation profile. Understanding these effects would provide a crucial tool for the rational design of drug delivery systems. While particles resembling red blood cells (RBCs) in size, shape and deformability have extended circulation times and altered biodistribution profiles compared to rigid, but otherwise similar particles, the in vivo behavior of such highly deformable particles of varied size has not been explored. We report the fabrication of a series of discoid, monodisperse, low-modulus hydrogel particles with diameters ranging from 0.8 to 8.9 μm, spanning sizes smaller than and larger than RBCs. We injected these particles into healthy mice, and tracked their concentration in the blood and their distribution into major organs. These deformable particles all demonstrated some hold up in filtration tissues like the lungs and spleen, followed by release back into the circulation, characterized by decreases in particles in these tissues with concomitant increases in particle concentration in blood. Particles similar to red blood cells in size demonstrated longer circulation times, suggesting that this size and shape of deformable particle is uniquely suited to avoid clearance. PMID:22705460

  3. CHARACTERIZATION OF FLAME-SYNTHESIZED FE, CO, OR MN-DOPED TITANIA NANOSTRUCTURED PARTICLES

    EPA Science Inventory

    The flame-synthesized catalysts have higher surface areas than commercial-grade titania and are composed of nanometer-sized primary particles with low internal porosity. Preliminary studies suggest that flame-synthesized iron-doped titania may be photoactivated in the visible lig...

  4. Diamond MEMS: wafer scale processing, devices, and technology insertion

    NASA Astrophysics Data System (ADS)

    Carlisle, J. A.

    2009-05-01

    Diamond has long held the promise of revolutionary new devices: impervious chemical barriers, smooth and reliable microscopic machines, and tough mechanical tools. Yet it's been an outsider. Laboratories have been effectively growing diamond crystals for at least 25 years, but the jump to market viability has always been blocked by the expense of diamond production and inability to integrate with other materials. Advances in chemical vapor deposition (CVD) processes have given rise to a hierarchy of carbon films ranging from diamond-like carbon (DLC) to vapor-deposited diamond coatings, however. All have pros and cons based on structure and cost, but they all share some of diamond's heralded attributes. The best performer, in theory, is the purest form of diamond film possible, one absent of graphitic phases. Such a material would capture the extreme hardness, high Young's modulus and chemical inertness of natural diamond. Advanced Diamond Technologies Inc., Romeoville, Ill., is the first company to develop a distinct chemical process to create a marketable phase-pure diamond film. The material, called UNCD® (for ultrananocrystalline diamond), features grain sizes from 3 to 300 nm in size, and layers just 1 to 2 microns thick. With significant advantages over other thin films, UNCD is designed to be inexpensive enough for use in atomic force microscopy (AFM) probes, microelectromechanical machines (MEMS), cell phone circuitry, radio frequency devices, and even biosensors.

  5. Optimizing photophoresis and asymmetric force fields for grading of Brownian particles.

    PubMed

    Neild, Adrian; Ng, Tuck Wah; Woods, Timothy

    2009-12-10

    We discuss a scheme that incorporates restricted spatial input location, orthogonal sort, and movement direction features, with particle sorting achieved by using an asymmetric potential cycled on and off, while movement is accomplished by photophoresis. Careful investigation has uncovered the odds of sorting between certain pairs of particle sizes to be solely dependent on radii in each phase of the process. This means that the most effective overall sorting can be achieved by maximizing the number of phases. This optimized approach is demonstrated using numerical simulation to permit grading of a range of nanometer-scale particle sizes.

  6. Particles size distribution in diluted magnetic fluids

    NASA Astrophysics Data System (ADS)

    Yerin, Constantine V.

    2017-06-01

    Changes in particles and aggregates size distribution in diluted kerosene based magnetic fluids is studied by dynamic light scattering method. It has been found that immediately after dilution in magnetic fluids the system of aggregates with sizes ranging from 100 to 250-1000 nm is formed. In 50-100 h after dilution large aggregates are peptized and in the sample stationary particles and aggregates size distribution is fixed.

  7. Process for preparation of large-particle-size monodisperse latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, D. M. (Inventor)

    1981-01-01

    Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarge particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment.

  8. Planar particle/droplet size measurement technique using digital particle image velocimetry image data

    NASA Technical Reports Server (NTRS)

    Kadambi, Jaikrishnan R. (Inventor); Wernet, Mark P. (Inventor); Mielke, Amy F. (Inventor)

    2005-01-01

    A method for determining a mass flux of an entrained phase in a planar two-phase flow records images of particles in the two-phase flow. Respective sizes of the particles (the entrained phase) are determined as a function of a separation between spots identified on the particle images. Respective velocities of the particles are determined. The mass flux of the entrained phase is determined as a function of the size and velocity of the particles.

  9. Quantum memory enhanced nuclear magnetic resonance of nanometer-scale samples with a single spin in diamond

    NASA Astrophysics Data System (ADS)

    Aslam, Nabeel; Pfender, Matthias; Zaiser, Sebastian; Favaro de Oliveira, Felipe; Momenzadeh, S. Ali; Denisenko, Andrej; Isoya, Junichi; Neumann, Philipp; Wrachtrup, Joerg

    Recently nuclear magnetic resonance (NMR) of nanoscale samples at ambient conditions has been achieved with nitrogen-vacancy (NV) centers in diamond. So far the spectral resolution in the NV NMR experiments was limited by the sensor's coherence time, which in turn prohibited revealing the chemical composition and dynamics of the system under investigation. By entangling the NV electron spin sensor with a long-lived memory spin qubit we increase the spectral resolution of NMR measurement sequences for the detection of external nuclear spins. Applying the latter sensor-memory-couple it is particularly easy to track diffusion processes, to identify the molecules under study and to deduce the actual NV center depth inside the diamond. We performed nanoscale NMR on several liquid and solid samples exhibiting unique NMR response. Our method paves the way for nanoscale identification of molecule and protein structures and dynamics of conformational changes.

  10. Filler particle size and composite resin classification systems.

    PubMed

    Lang, B R; Jaarda, M; Wang, R F

    1992-11-01

    The currently used composite resin classification systems need review if they are to continue to serve as descriptives and quantitative parameters denoting the filler particle content of these materials. Examination of the particles in 12 composite resins using a technique of washing the filler particles from the matrix of the composite resin was presented as yet another method of grouping composites according to filler particle content. Light microscopic examination of the filler particles that remained provided a separation of the 12 materials into four easily distinguished groups based on filler particle sizes. The wear of the 12 composite resins determined in a previous study was examined in relation to the classification of the materials by the currently available systems. The wear values were also examined using the groupings of the materials according to their filler particle sizes as determined by separating the particles from the matrix by the washing technique. Grouping composites on the basis of the filler particle sizes found after washing was easily correlated with wear and supported the suggestion that composites with smaller filler particles wear less.

  11. Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

    NASA Astrophysics Data System (ADS)

    Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

    2013-12-01

    We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

  12. Growth of diamond by RF plasma-assisted chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Meyer, Duane E.; Ianno, Natale J.; Woollam, John A.; Swartzlander, A. B.; Nelson, A. J.

    1988-01-01

    A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

  13. Development of Innovative Accident Tolerant High Thermal Conductivity UO 2-Diamond Composite Fuel Pellets

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

    Tulenko, James; Subhash, Ghatu

    2016-01-01

    The University of Florida (UF) evaluated a composite fuel consisting of UO 2 powder mixed with diamond micro particles as a candidate as an accident-tolerant fuel (ATF). The research group had previous extensive experience researching with diamond micro particles as an addition to reactor coolant for improved plant thermal performance. The purpose of this research work was to utilize diamond micro particles to develop UO 2-Diamond composite fuel pellets with significantly enhanced thermal properties, beyond that already being measured in the previous UF research projects of UO 2 – SiC and UO 2 – Carbon Nanotube fuel pins. UF ismore » proving with the current research results that the addition of diamond micro particles to UO 2 may greatly enhanced the thermal conductivity of the UO 2 pellets producing an accident-tolerant fuel. The Beginning of life benefits have been proven and fuel samples are being irradiated in the ATR reactor to confirm that the thermal conductivity improvements are still present under irradiation.« less

  14. Synergism between low-energy neutral particles and energetic ions in the pulsed glow discharge deposition of diamond-like carbon films

    NASA Astrophysics Data System (ADS)

    Afanasyev-Charkin, I. V.; Nastasi, M.

    2004-08-01

    Diamond-like carbon films were deposited using pulsed glow discharge deposition at 4kV. The duty factor was varied and all other parameters were kept constant. It was shown that the contribution of neutral particles to the total number of deposition atoms is much larger than that of energetic ions. At the same time, there is a relationship between the deposition of neutral particles and ion bombardment. The sticking coefficient of the neutral particles in proportional to the flux of energetic ions and does not exceed 5×10-4 for the deposition parameters used in our experiment.

  15. Suppression of coffee ring: (Particle) size matters

    NASA Astrophysics Data System (ADS)

    Bansal, Lalit; Seth, Pranjal; Murugappan, Bhubesh; Basu, Saptarshi

    2018-05-01

    Coffee ring patterns in drying sessile droplets are undesirable in various practical applications. Here, we experimentally demonstrate that on hydrophobic substrates, the coffee ring can be suppressed just by increasing the particle diameter. Particles with larger size flocculate within the evaporation timescale, leading to a significant gravimetric settling (for Pe > 1) triggering a uniform deposit. Interestingly, the transition to a uniform deposit is found to be independent of the internal flow field and substrate properties. Flocculation of particles also alters the particle packing at the nanoscale resulting in order to disorder transitions. In this letter, we exhibit a physical exposition on how particle size affects morphodynamics of the droplet drying at macro-nano length scales.

  16. Membranes for nanometer-scale mass fast transport

    DOEpatents

    Bakajin, Olgica [San Leandro, CA; Holt, Jason [Berkeley, CA; Noy, Aleksandr [Belmont, CA; Park, Hyung Gyu [Oakland, CA

    2011-10-18

    Nanoporous membranes comprising single walled, double walled, and multiwalled carbon nanotubes embedded in a matrix material were fabricated for fluid mechanics and mass transfer studies on the nanometer scale and commercial applications. Average pore size can be 2 nm to 20 nm, or seven nm or less, or two nanometers or less. The membrane can be free of large voids spanning the membrane such that transport of material such as gas or liquid occurs exclusively through the tubes. Fast fluid, vapor, and liquid transport are observed. Versatile micromachining methods can be used for membrane fabrication. A single chip can comprise multiple membranes. These membranes are a robust platform for the study of confined molecular transport, with applications in liquid and gas separations and chemical sensing including desalination, dialysis, and fabric formation.

  17. Mechanisms for the formation and growth of nanometer-sized particles in the Amazon: New insights from GoAmazon2014 and the Tapajos Upwind Forest Flux Study (TUFFS).

    NASA Astrophysics Data System (ADS)

    Smith, J. N.; Park, J. H.; Kuang, C.; Bustillos, J. O. V.; Souza, R. A. F. D.; Wiedemann, K. T.; Munger, J. W.; Wofsy, S. C.; Rizzo, L. V.; Artaxo, P.; Martin, S. T.; Seco, R.; Kim, S.; Guenther, A. B.; Batalha, S. S. A.; Alves, E. G.; Tota, J.

    2014-12-01

    The Amazon rainforest is a unique and important place for studying aerosol formation and its impacts on atmospheric chemistry and climate. In remote areas, the atmosphere is characterized by low particle number concentrations and high humidity; perturbations in the particle number concentrations and climate-relevant physical and chemical properties could therefore have a great impact on cloud formation and thus on regional climate and precipitation. While it was previously believed that new particle formation occurs rarely in the Amazon, observations in the Amazon of a sustained steady-state particle number concentration, along with an abundance of dry and wet surfaces upon which particles may deposit, imply that sources of new particles must exist in this region. We present observations from two studies, GOAmazon2014 and Tapajos Upwind Forest Flux Study (TUFFS), which seek to identify and quantify the sources of aerosol particles in the Amazon. Measurements of the chemical composition of 20 - 100 nm diameter aerosol particles at the T3 measurement site during the wet and dry season campaigns of GOAmazon2014 show the presence of inorganic ions such as potassium ion and sulfate, as well as organic ion such as oxalate, in ambient nanoparticles. These observations, combined with 1.5 - 300 nm diameter particle number size distributions and trace gas measurements of organic compounds and sulfuric acid, are used to determine the relative importance of sulfuric acid, organic compounds, and primary biological particle emissions to nanoparticle formation and growth. Observations of 3 - 100 nm diameter particle number size distributions at the KM67 tower site during TUFFS show frequent new particle formation events during the wet season in April, transitioning to a scenario of less frequent events in July at the onset of the dry season. These observations highlight the regional nature of new particle formation in the Amazon, and suggest that additional observations at a

  18. Sound absorption by suspensions of nonspherical particles: Measurements compared with predictions using various particle sizing techniques

    NASA Astrophysics Data System (ADS)

    Richards, Simon D.; Leighton, Timothy G.; Brown, Niven R.

    2003-10-01

    Knowledge of the particle size distribution is required in order to predict ultrasonic absorption in polydisperse particulate suspensions. This paper shows that the method used to measure the particle size distribution can lead to important differences in the predicted absorption. A reverberation technique developed for measuring ultrasonic absorption by suspended particles is used to measure the absorption in suspensions of nonspherical particles. Two types of particulates are studied: (i) kaolin (china clay) particles which are platelike in form; and (ii) calcium carbonate particles which are more granular. Results are compared to theoretical predictions of visco-inertial absorption by suspensions of spherical particles. The particle size distributions, which are required for these predictions, are measured by laser diffraction, gravitational sedimentation and centrifugal sedimentation, all of which assume spherical particles. For a given sample, each sizing technique yields a different size distribution, leading to differences in the predicted absorption. The particle size distributions obtained by gravitational and centrifugal sedimentation are reinterpreted to yield a representative size distribution of oblate spheroids, and predictions for absorption by these spheroids are compared with the measurements. Good agreement between theory and measurement for the flat kaolin particles is obtained, demonstrating that these particles can be adequately represented by oblate spheroids.

  19. Microstructural characterization and strengthening behavior of nanometer sized carbides in Ti–Mo microalloyed steels during continuous cooling process

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

    Chen, Chih-Yuan, E-mail: chen6563@gmail.com; Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan; Yang, Jer-Ren, E-mail: jryang@ntu.edu.tw

    Nanometer-sized carbides that precipitated in a Ti–Mo bearing steel after interrupted continuous cooling in a temperature range of 620–700 °C with or without hot deformation were investigated by field-emission-gun transmission electron microscopy. The nanometer-sized carbides were identified as randomly homogeneous precipitation carbides and interphase precipitation carbides coexisting in the ferrite matrix. It is found that this dual precipitation morphology of carbides in the steel leads to the non-uniform mechanical properties of individual ferrite grains. Vickers hardness data mainly revealed that, in the specimens cooled at a rate of 0.5 °C/s without hot deformation, the range of Vickers hardness distribution wasmore » 230–340 HV 0.1 when cooling was interrupted at 680 °C, and 220–360 HV 0.1 when cooling was interrupted at 650 °C. For the specimens cooled at a rate of 0.5 °C/s with hot deformation, the range of Vickers hardness distribution was 290–360 HV 0.1 when cooling was interrupted at 680 °C, and 280–340 HV 0.1 when cooling was interrupted at 650 °C. Therefore, a narrower range of hardness distribution occurred in the specimens that underwent hot deformation and were then cooled with a lower interrupted cooling temperature. The uniform precipitation status in each ferrite grain can lead to ferrite grains with a narrower Vickers hardness distribution. On the other hand, interrupted cooling produced a maximum Vickers hardness of 320–330 HV 0.1 for the hot deformed specimens and 290–310 HV 0.1 for the non-deformed specimens with cooling interrupted in the temperature range of 660–670 °C. The maximum Vickers hardness obtained in such a temperature range can be ascribed to the full precipitation of the microalloying elements in the supersaturated ferrite matrix with a tiny size (~ 4–7 nm). - Highlight: • The interrupted continuous cooling temperatures were 620 °C to 700 °C. • Precipitation carbides with dual dispersed

  20. Enhanced size-dependent trapping of particles using microvortices

    PubMed Central

    Zhou, Jian; Kasper, Susan; Papautsky, Ian

    2013-01-01

    Inertial microfluidics has been attracting considerable interest for size-based separation of particles and cells. The inertial forces can be manipulated by expanding the microchannel geometry, leading to formation of microvortices which selectively isolate and trap particles or cells from a mixture. In this work, we aim to enhance our understanding of particle trapping in such microvortices by developing a model of selective particle trapping. Design and operational parameters including flow conditions, size of the trapping region, and target particle concentration are explored to elucidate their influence on trapping behavior. Our results show that the size dependence of trapping is characterized by a threshold Reynolds number, which governs the selective entry of particles into microvortices from the main flow. We show that concentration enhancement on the order of 100,000× and isolation of targets at concentrations in the 1/mL is possible. Ultimately, the insights gained from our systematic investigation suggest optimization solutions that enhance device performance (efficiency, size selectivity, and yield) and are applicable to selective isolation and trapping of large rare cells as well as other applications. PMID:24187531

  1. Effect of Titanium Addition on the Thermal Properties of Diamond/Cu-Ti Composites Fabricated by Pressureless Liquid-Phase Sintering Technique

    PubMed Central

    Chung, Chih-Yu; Chu, Chao-Hung; Lee, Mu-Tse; Lin, Chun-Ming; Lin, Su-Jien

    2014-01-01

    In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m·K for 50 vol% diamond/Cu-0.6  at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained. PMID:24715816

  2. Artificial neural network based particle size prediction of polymeric nanoparticles.

    PubMed

    Youshia, John; Ali, Mohamed Ehab; Lamprecht, Alf

    2017-10-01

    Particle size of nanoparticles and the respective polydispersity are key factors influencing their biopharmaceutical behavior in a large variety of therapeutic applications. Predicting these attributes would skip many preliminary studies usually required to optimize formulations. The aim was to build a mathematical model capable of predicting the particle size of polymeric nanoparticles produced by a pharmaceutical polymer of choice. Polymer properties controlling the particle size were identified as molecular weight, hydrophobicity and surface activity, and were quantified by measuring polymer viscosity, contact angle and interfacial tension, respectively. A model was built using artificial neural network including these properties as input with particle size and polydispersity index as output. The established model successfully predicted particle size of nanoparticles covering a range of 70-400nm prepared from other polymers. The percentage bias for particle prediction was 2%, 4% and 6%, for the training, validation and testing data, respectively. Polymer surface activity was found to have the highest impact on the particle size followed by viscosity and finally hydrophobicity. Results of this study successfully highlighted polymer properties affecting particle size and confirmed the usefulness of artificial neural networks in predicting the particle size and polydispersity of polymeric nanoparticles. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Synthesis of SiV-diamond particulates via the microwave plasma chemical deposition of ultrananocrystalline diamond on soda-lime glass fibers

    NASA Astrophysics Data System (ADS)

    Kunuku, Srinivasu; Chen, Yen-Chun; Yeh, Chien-Jui; Chang, Wen-Hao; Manoharan, Divinah; Leou, Keh-Chyang; Lin, I.-Nan

    2016-10-01

    We report the synthesis of silicon-vacancy (SiV) incorporated spherical shaped ultrananocrystalline diamond (SiV-UNCD) particulates (size ∼1 μm) with bright luminescence at 738 nm. For this purpose, different granular structured polycrystalline diamond films and particulates were synthesized by using three different kinds of growth plasma conditions on the three types of substrate materials in the microwave plasma enhanced CVD process. The grain size dependent photoluminescence properties of nitrogen vacancy (NV) and SiV color centers have been investigated for different granular structured diamond samples. The luminescence of NV center and the associated phonon sidebands, which are usually observed in microcrystalline diamond and nanocrystalline diamond films, were effectively suppressed in UNCD films and UNCD particulates. Micron sized SiV-UNCD particulates with bright SiV emission has been attained by transfer of SiV-UNCD clusters on soda-lime glass fibers to inverted pyramidal cavities fabricated on Si substrates by the simple crushing of UNCD/soda-lime glass fibers in deionized water and ultrasonication. Such a plasma enhanced CVD process for synthesizing SiV-UNCD particulates with suppressed NV emission is simple and robust to attain the bright SiV-UNCD particulates to employ in practical applications.

  4. Formation of diamond nanoparticle thin films by electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Goto, Yosuke; Ohishi, Fujio; Tanaka, Kuniaki; Usui, Hiroaki

    2016-03-01

    Thin films of diamond nanoparticles were prepared by electrophoretic deposition (EPD) using 0.5 wt % dispersions in water, ethanol, and 2-propanol. The film growth rate increased with increasing voltage applied to the electrodes. However, an excessive increase in voltage caused the degradation of film morphology. The optimum voltage was 4 V with an electrode separation of 5 mm. The film growth rate was higher in organic solvents than in water. The deposited film had a smooth surface with an average surface roughness comparable to the size of primary particles of the source material. It is notable that the EPD films had a considerably higher physical stability than spin-coated and cast films. The stability was further improved by thermally annealing the films. IR analysis revealed that the diamond nanoparticles have carboxy and amino groups on their surfaces. It is considered that the stability of the EPD films originate from a chemical reaction between these functional groups.

  5. Parallel particle impactor - novel size-selective particle sampler for accurate fractioning of inhalable particles

    NASA Astrophysics Data System (ADS)

    Trakumas, S.; Salter, E.

    2009-02-01

    Adverse health effects due to exposure to airborne particles are associated with particle deposition within the human respiratory tract. Particle size, shape, chemical composition, and the individual physiological characteristics of each person determine to what depth inhaled particles may penetrate and deposit within the respiratory tract. Various particle inertial classification devices are available to fractionate airborne particles according to their aerodynamic size to approximate particle penetration through the human respiratory tract. Cyclones are most often used to sample thoracic or respirable fractions of inhaled particles. Extensive studies of different cyclonic samplers have shown, however, that the sampling characteristics of cyclones do not follow the entire selected convention accurately. In the search for a more accurate way to assess worker exposure to different fractions of inhaled dust, a novel sampler comprising several inertial impactors arranged in parallel was designed and tested. The new design includes a number of separated impactors arranged in parallel. Prototypes of respirable and thoracic samplers each comprising four impactors arranged in parallel were manufactured and tested. Results indicated that the prototype samplers followed closely the penetration characteristics for which they were designed. The new samplers were found to perform similarly for liquid and solid test particles; penetration characteristics remained unchanged even after prolonged exposure to coal mine dust at high concentration. The new parallel impactor design can be applied to approximate any monotonically decreasing penetration curve at a selected flow rate. Personal-size samplers that operate at a few L/min as well as area samplers that operate at higher flow rates can be made based on the suggested design. Performance of such samplers can be predicted with high accuracy employing well-established impaction theory.

  6. High Temperature Mechanical Behavior of Polycrystalline Alumina from Mixed Nanometer and Micrometer Powders

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2001-01-01

    Sintered aluminum oxide materials were formed using commercial methods from mechanically mixed powders of nano-and micrometer alumina. The powders were consolidated at 1500 and 1600 C with 3.2 and 7.2 ksi applied stress in argon. The conventional micrometer sized powders failed to consolidate. While 100 percent nanometer-sized alumina and its mixture with the micrometer powders achieved less than 99 percent density. Preliminary high temperature creep behavior indicates no super-plastic strains. However high strains (less than 0.65 percent) were generated in the nanometer powder, due to cracks and linked voids initiated by cavitation.

  7. Size resolved ultrafine particles emission model--a continues size distribution approach.

    PubMed

    Nikolova, Irina; Janssen, Stijn; Vrancken, Karl; Vos, Peter; Mishra, Vinit; Berghmans, Patrick

    2011-08-15

    A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving. The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E+14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found. For the size distributions it is found that the measured distributions consist of three modes--Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.04-0.05 μm) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed. Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected. The UFPEM emission model can be used as a source term in dispersion models. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Effect of biochar particle size on hydrophobic organic compound sorption kinetics: Applicability of using representative size.

    PubMed

    Kang, Seju; Jung, Jihyeun; Choe, Jong Kwon; Ok, Yong Sik; Choi, Yongju

    2018-04-01

    Particle size of biochar may strongly affect the kinetics of hydrophobic organic compound (HOC) sorption. However, challenges exist in characterizing the effect of biochar particle size on the sorption kinetics because of the wide size range of biochar. The present study suggests a novel method to determine a representative value that can be used to show the dependence of HOC sorption kinetics to biochar particle size on the basis of an intra-particle diffusion model. Biochars derived from three different feedstocks are ground and sieved to obtain three daughter products each having different size distributions. Phenanthrene sorption kinetics to the biochars are well described by the intra-particle diffusion model with significantly greater sorption rates observed for finer grained biochars. The time to reach 95% of equilibrium for phenanthrene sorption to biochar is reduced from 4.6-17.9days for the original biochars to <1-4.6days for the powdered biochars with <125μm in size. A moderate linear correlation is found between the inverse square of the representative biochar particle radius obtained using particle size distribution analysis and the apparent phenanthrene sorption rates determined by the sorption kinetics experiments and normalized to account for the variation of the sorption rate-determining factors other than the biochar particle radius. The results suggest that the representative biochar particle radius reasonably describes the dependence of HOC sorption rates on biochar particle size. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Effects of diamond nanoparticle exposure on the internal structure and reproduction of Daphnia magna.

    PubMed

    Mendonça, Elsa; Diniz, Mário; Silva, Luís; Peres, Isabel; Castro, Luísa; Correia, José Brito; Picado, Ana

    2011-02-15

    Nanomaterials have significant technological advantages but their release into the environment also carry potential ecotoxicological risks. Carbon-based nanoparticles and particularly diamond nanoparticles have numerous industrial and medical applications. The aim of the present study was to evaluate the toxic effects of diamond nanoparticles with an average particle size of 20 nm on the survival, reproduction and tissue structure of the freshwater crustacean Daphnia magna. The chronic toxicity test results showed 100% mortality at concentrations higher than 12.5 mg l(-1) and that reproduction inhibition occurred in concentrations higher than 1.3 mg l(-1). Light microscopy showed that diamond nanoparticles adhere to the exoskeleton surface and accumulate within the gastrointestinal tract, suggesting that food absorption by the gut cells may be blocked. The results support the use of chronic approaches in environmental protection as part of an integrated environmental monitoring and assessment strategy. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Influence of feedstock particle size on lignocellulose conversion--a review.

    PubMed

    Vidal, Bernardo C; Dien, Bruce S; Ting, K C; Singh, Vijay

    2011-08-01

    Feedstock particle sizing can impact the economics of cellulosic ethanol commercialization through its effects on conversion yield and energy cost. Past studies demonstrated that particle size influences biomass enzyme digestibility to a limited extent. Physical size reduction was able to increase conversion rates to maximum of ≈ 50%, whereas chemical modification achieved conversions of >70% regardless of biomass particle size. This suggests that (1) mechanical pretreatment by itself is insufficient to attain economically feasible biomass conversion, and, therefore, (2) necessary particle sizing needs to be determined in the context of thermochemical pretreatment employed for lignocellulose conversion. Studies of thermochemical pretreatments that have taken into account particle size as a factor have exhibited a wide range of maximal sizes (i.e., particle sizes below which no increase in pretreatment effectiveness, measured in terms of the enzymatic conversion resulting from the pretreatment, were observed) from <0.15 to 50 mm. Maximal sizes as defined above were dependent on the pretreatment employed, with maximal size range decreasing as follows: steam explosion > liquid hot water > dilute acid and base pretreatments. Maximal sizes also appeared dependent on feedstock, with herbaceous or grassy biomass exhibiting lower maximal size range (<3 mm) than woody biomass (>3 mm). Such trends, considered alongside the intensive energy requirement of size reduction processes, warrant a more systematic study of particle size effects across different pretreatment technologies and feedstock, as a requisite for optimizing the feedstock supply system.

  11. Potential environmental influences on variation in body size and sexual size dimorphism among Arizona populations of the western diamond-backed rattlesnake (Crotalus atrox)

    USGS Publications Warehouse

    Amarello, Melissa; Nowak, Erica M.; Taylor, Emily N.; Schuett, Gordon W.; Repp, Roger A.; Rosen, Philip C.; Hardy, David L.

    2010-01-01

    Differences in resource availability and quality along environmental gradients are important influences contributing to intraspecific variation in body size, which influences numerous life-history traits. Here, we examined variation in body size and sexual size dimorphism (SSD) in relation to temperature, seasonality, and precipitation among 10 populations located throughout Arizona of the western diamond-backed rattlesnake (Crotalus atrox). Specifically, in our analyses we addressed the following questions: (i) Are adult males larger in cooler, wetter areas? (ii) Does female body size respond differently to environmental variation? (iii) Is seasonality a better predictor of body size variation? (iv) Is SSD positively correlated with increased resources? We demonstrate that male and female C. atrox are larger in body size in cooler (i.e., lower average annual maximum, minimum, and mean temperature) and wetter areas (i.e., higher average annual precipitation, more variable precipitation, and available surface water). Although SSD in C. atrox appeared to be more pronounced in cooler, wetter areas, this relationship did not achieve statistical significance.

  12. First Principles Study of Nanodiamond Optical and Electronic Properties

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

    Raty, J; Galli, G

    2004-10-21

    Nanometer sized diamond has been found in meteorites, proto-planetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles appears to be peaked around 2-5 nm, and to be largely independent of preparation conditions. Using ab-initio calculations, we have shown that in this size range nanodiamond has a fullerene-like surface and, unlike silicon and germanium, exhibits very weak quantum confinement effects. We called these carbon nanoparticles bucky-diamonds: their atomic structure, predicted by simulations, is consistent with many experimental findings. In addition, we carried out calculations of the stabilitymore » of nanodiamond which provided a unifying explanation of its size distribution in extra-terrestrial samples, and in ultra-crystalline diamond films.« less

  13. Biodistribution of amino-functionalized diamond nanoparticles. In vivo studies based on 18F radionuclide emission.

    PubMed

    Rojas, Santiago; Gispert, Juan D; Martín, Roberto; Abad, Sergio; Menchón, Cristina; Pareto, Deborah; Víctor, Víctor M; Alvaro, Mercedes; García, Hermenegildo; Herance, J Raúl

    2011-07-26

    Nanoparticles have been proposed for several biomedical applications; however, in vivo biodistribution studies to confirm their potential are scarce. Nanodiamonds are carbon nanoparticles that have been recently proposed as a promising biomaterial. In this study, we labeled nanodiamonds with (18)F to study their in vivo biodistribution by positron emission tomography. Moreover, the impact on the biodistribution of their kinetic particle size and of the surfactant agents has been evaluated. Radiolabeled diamond nanoparticles accumulated mainly in the lung, spleen, and liver and were excreted into the urinary tract. The addition of surfactant agents did not lead to significant changes in this pattern, with the exception of a slight reduction in the urinary excretion rate. On the other hand, after filtration of the radiolabeled diamond nanoparticles to remove those with a larger kinetic size, the uptake in the lung and spleen was completely inhibited and significantly reduced in the liver.

  14. Transient current induced in thin film diamonds by swift heavy ions

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

    Sato, Shin-ichiro; Makino, Takahiro; Ohshima, Takeshi

    Single crystal diamond is a suitable material for the next generation particle detectors because of the superior electrical properties and the high radiation tolerance. In order to investigate charge transport properties of diamond particle detectors, transient currents generated in diamonds by single swift heavy ions (26 MeV O 5 + and 45 MeV Si 7 +) are investigated. We also measured two dimensional maps of transient currents by single ion hits. In the case of 50 μm-thick diamond, both the signal height and the collected charge are reduced by the subsequent ion hits and the charge collection time is extended.more » Our results are thought to be attributable to the polarization effect in diamond and it appears only when the transient current is dominated by hole current. In the case of 6 μm-thick diamond membrane, an “island” structure is found in the 2D map of transient currents. Signals in the islands shows different applied bias dependence from signals in other regions, indicating different crystal and/or metal contact quality. Simulation study of transient currents based on the Shockley-Ramo theorem clarifies that accumulation of space charges changes distribution of electric field in diamond and causes the polarization effect.« less

  15. Transient current induced in thin film diamonds by swift heavy ions

    DOE PAGES

    Sato, Shin-ichiro; Makino, Takahiro; Ohshima, Takeshi; ...

    2017-04-05

    Single crystal diamond is a suitable material for the next generation particle detectors because of the superior electrical properties and the high radiation tolerance. In order to investigate charge transport properties of diamond particle detectors, transient currents generated in diamonds by single swift heavy ions (26 MeV O 5 + and 45 MeV Si 7 +) are investigated. We also measured two dimensional maps of transient currents by single ion hits. In the case of 50 μm-thick diamond, both the signal height and the collected charge are reduced by the subsequent ion hits and the charge collection time is extended.more » Our results are thought to be attributable to the polarization effect in diamond and it appears only when the transient current is dominated by hole current. In the case of 6 μm-thick diamond membrane, an “island” structure is found in the 2D map of transient currents. Signals in the islands shows different applied bias dependence from signals in other regions, indicating different crystal and/or metal contact quality. Simulation study of transient currents based on the Shockley-Ramo theorem clarifies that accumulation of space charges changes distribution of electric field in diamond and causes the polarization effect.« less

  16. Anomalous change of Airy disk with changing size of spherical particles

    NASA Astrophysics Data System (ADS)

    Pan, Linchao; Zhang, Fugen; Meng, Rui; Xu, Jie; Zuo, Chenze; Ge, Baozhen

    2016-02-01

    Use of laser diffraction is considered as a method of reliable principle and mature technique in measurements of particle size distributions. It is generally accepted that for a certain relative refractive index, the size of the scattering pattern (also called Airy disk) of spherical particles monotonically decreases with increasing particle size. This fine structure forms the foundation of the laser diffraction method. Here we show that the Airy disk size of non-absorbing spherical particles becomes larger with increasing particle size in certain size ranges. To learn more about this anomalous change of Airy disk (ACAD), we present images of Airy disk and curves of Airy disk size versus particle size for spherical particles of different relative refractive indices by using Mie theory. These figures reveal that ACAD occurs periodically for non-absorbing particles and will disappear when the absorbing efficiency is higher than certain value. Then by using geometrical optics (GO) approximation, we derive the analytical formulae for the bounds of the size ranges where ACAD occurs. From the formulae, we obtain laws of ACAD as follows: (1) for non-absorbing particles, ACAD occurs periodically, and when the particle size tends to infinity, the period tends to a certain value. As the relative refractive index increases, (2) the particle size ranges where ACAD occurs shift to smaller values, (3) the period of ACAD becomes smaller, and (4) the width of the size ranges where ACAD occurs becomes narrower. In addition, we can predict from the formulae that ACAD also exists for particles whose relative refractive index is smaller than 1.

  17. Particle sizing of pharmaceutical aerosols via direct imaging of particle settling velocities.

    PubMed

    Fishler, Rami; Verhoeven, Frank; de Kruijf, Wilbur; Sznitman, Josué

    2018-02-15

    We present a novel method for characterizing in near real-time the aerodynamic particle size distributions from pharmaceutical inhalers. The proposed method is based on direct imaging of airborne particles followed by a particle-by-particle measurement of settling velocities using image analysis and particle tracking algorithms. Due to the simplicity of the principle of operation, this method has the potential of circumventing potential biases of current real-time particle analyzers (e.g. Time of Flight analysis), while offering a cost effective solution. The simple device can also be constructed in laboratory settings from off-the-shelf materials for research purposes. To demonstrate the feasibility and robustness of the measurement technique, we have conducted benchmark experiments whereby aerodynamic particle size distributions are obtained from several commercially-available dry powder inhalers (DPIs). Our measurements yield size distributions (i.e. MMAD and GSD) that are closely in line with those obtained from Time of Flight analysis and cascade impactors suggesting that our imaging-based method may embody an attractive methodology for rapid inhaler testing and characterization. In a final step, we discuss some of the ongoing limitations of the current prototype and conceivable routes for improving the technique. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Dynamics of diamond nanoparticles in solution and cells.

    PubMed

    Neugart, Felix; Zappe, Andrea; Jelezko, Fedor; Tietz, C; Boudou, Jean Paul; Krueger, Anke; Wrachtrup, Jörg

    2007-12-01

    The fluorescence and motional dynamics of single diamond nanocrystals in buffer solution and in living cells is investigated. Stable hydrosols of nanodiamonds in buffer solutions are investigated by fluorescence correlation spectroscopy. Measurement of the effective hydrodynamic radius yields particles of 48 nm diameter, which is in excellent agreement with atomic force microscopy measurements made on the same particles. Fluorescence correlation spectroscopy measurements indicate that nanocrystals easily form aggregates when the buffer pH is changed. This tendency is reduced when the surface of the diamonds is covered with surfactants. Upon incubation, cells spontaneously take up nanocrystals that uniformly distribute in cells. Most of the particles get immobilized within a few minutes. The binding of streptavidin to biotinylated aggregates of 4 nm diameter nanodiamonds is demonstrated.

  19. Particle size analysis of some water/oil/water multiple emulsions.

    PubMed

    Ursica, L; Tita, D; Palici, I; Tita, B; Vlaia, V

    2005-04-29

    Particle size analysis gives useful information about the structure and stability of multiple emulsions, which are important characteristics of these systems. It also enables the observation of the growth process of particles dispersed in multiple emulsions, accordingly, the evolution of their dimension in time. The size of multiple particles in the seven water/oil/water (W/O/W) emulsions was determined by measuring the particles size observed during the microscopic examination. In order to describe the distribution of the size of multiple particles, the value of two parameters that define the particle size was calculated: the arithmetical mean diameter and the median diameter. The results of the particle size analysis in the seven multiple emulsions W/O/W studied are presented as histograms of the distribution density immediately, 1 and 3 months after the preparation of each emulsion, as well as by establishing the mean and the median diameter of particles. The comparative study of the distribution histograms and of the mean and median diameters of W/O/W multiple particles indicates that the prepared emulsions are fine and very fine dispersions, stable, and presenting a growth of the abovementioned diameters during the study.

  20. Spectral analysis of the structure of ultradispersed diamonds

    NASA Astrophysics Data System (ADS)

    Uglov, V. V.; Shimanski, V. I.; Rusalsky, D. P.; Samtsov, M. P.

    2008-07-01

    The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles changes during the treatment.

  1. Development of single nanometer-sized ultrafine oxygen bubbles to overcome the hypoxia-induced resistance to radiation therapy via the suppression of hypoxia-inducible factor-1α

    PubMed Central

    Honma, Kyoko; Nakano, Takashi; Asao, Takayuki; Kuwahara, Ryusuke; Aoyama, Kazuhiro; Yasuda, Hidehiro; Kelly, Matthew; Kuwano, Hiroyuki

    2018-01-01

    Radiation therapy can result in severe side-effects, including the development of radiation resistance. The aim of this study was to validate the use of oxygen nanobubble water to overcome resistance to radiation in cancer cell lines via the suppression of the hypoxia-inducible factor 1-α (HIF-1α) subunit. Oxygen nanobubble water was created using a newly developed method to produce nanobubbles in the single-nanometer range with the ΣPM-5 device. The size and concentration of the oxygen nanobubbles in the water was examined using a cryo-transmission electron microscope. The nanobubble size was ranged from 2 to 3 nm, and the concentration of the nanobubbles was calculated at 2×1018 particles/ml. Cell viability and HIF-1α levels were evaluated in EBC-1 lung cancer and MDA-MB-231 breast cancer cells treated with or without the nanobubble water and radiation under normoxic and hypoxic conditions in vitro. The cancer cells grown in oxygen nanobubble-containing media exhibited a clear suppression of hypoxia-induced HIF-1α expression compared to the cells grown in media made with distilled water. Under hypoxic conditions, the EBC-1 and MDA-MB231 cells displayed resistance to radiation compared to the cells cultured under normoxic cells. The use of oxygen nanobubble medium significantly suppressed the hypoxia-induced resistance to radiation compared to the use of normal medium at 2, 6, 10 and 14 Gy doses. Importantly, the use of nanobubble media did not affect the viability and radiation sensitivity of the cancer cell lines, or the non-cancerous cell line, BEAS-2B, under normoxic conditions. This newly created single-nanometer range oxygen nanobubble water, without any additives, may thus prove to be a promising agent which may be used to overcome the hypoxia-induced resistance of cancer cells to radiation via the suppression of HIF-1α. PMID:29393397

  2. The Nanometer-Sized Eutectic Structure of Si/CrSi2 Thermoelectric Materials Fabricated by Rapid Solidification

    NASA Astrophysics Data System (ADS)

    Norizan, Mohd Natashah; Miyazaki, Yoshinobu; Ohishi, Yuji; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke

    2018-04-01

    Nanostructuring is known to be an effective method to improve thermoelectric performance but, generally, it requires complex procedures and much labor. In the present study, self-assembled nanometer-sized composite structures of silicon (Si) and chromium disilicide (CrSi2) were easily fabricated by the rapid solidification of a melt with a eutectic composition. Ribbon-like samples were obtained with a dominant nanostructure of fine aligned lamellae with a spacing range of 20-35 nm. The thermoelectric power factor of the ribbon was observed to be 1.2 mW/mK2 at room temperature and reached 3.0 mW/mK2 at 773 K. The thermal conductivity was 65% lower than that of a bulk eutectic sample. The results suggest that this method is promising for fabricating an effective nanostructure for thermoelectric performance.

  3. Monodisperse Block Copolymer Particles with Controllable Size, Shape, and Nanostructure

    NASA Astrophysics Data System (ADS)

    Shin, Jae Man; Kim, Yongjoo; Kim, Bumjoon; PNEL Team

    Shape-anisotropic particles are important class of novel colloidal building block for their functionality is more strongly governed by their shape, size and nanostructure compared to conventional spherical particles. Recently, facile strategy for producing non-spherical polymeric particles by interfacial engineering received significant attention. However, achieving uniform size distribution of particles together with controlled shape and nanostructure has not been achieved. Here, we introduce versatile system for producing monodisperse BCP particles with controlled size, shape and morphology. Polystyrene-b-polybutadiene (PS-b-PB) self-assembled to either onion-like or striped ellipsoid particle, where final structure is governed by amount of adsorbed sodium dodecyl sulfate (SDS) surfactant at the particle/surrounding interface. Further control of molecular weight and particle size enabled fine-tuning of aspect ratio of ellipsoid particle. Underlying physics of free energy for morphology formation and entropic penalty associated with bending BCP chains strongly affects particle structure and specification.

  4. Particle interaction of lubricated or unlubricated binary mixtures according to their particle size and densification mechanism.

    PubMed

    Di Martino, Piera; Joiris, Etienne; Martelli, Sante

    2004-09-01

    The aim of this study is to assess an experimental approach for technological development of a direct compression formulation. A simple formula was considered composed by an active ingredient, a diluent and a lubricant. The active ingredient and diluent were selected as an example according to their typical densification mechanism: the nitrofurantoine, a fragmenting material, and the cellulose microcrystalline (Vivapur), which is a typical visco-elastic material, equally displaying good bind and disintegrant properties. For each ingredient, samples of different particle size distribution were selected. Initially, tabletability of pure materials was studied by a rotary press without magnesium stearate. Vivapur tabletability decreases with increase in particle size. The addition of magnesium stearate as lubricant decreases tabletability of Vivapur of greater particle size, while it kept unmodified that of Vivapur of lower particle size. Differences in tabletability can be related to differences in particle-particle interactions; for Vivapur of higher particle size (Vivapur 200, 102 and 101), the lower surface area develops lower surface available for bonds, while for Vivapur of lower particle size (99 and 105) the greater surface area allows high particle proximity favouring particle cohesivity. Nitrofurantoine shows great differences in compression behaviour according to its particle size distribution. Large crystals show poorer tabletability than fine crystals, further decreased by lubricant addition. The large crystals poor tabletability is due to their poor compactibility, in spite of high compressibility and plastic intrinsic deformability; in fact, in spite of the high densification tendency, the nature of the involved bonds is very weak. Nitrofurantoine samples were then mixed with Vivapurs in different proportions. Compression behaviour of binary mixes (tabletability and compressibility) was then evaluated according to diluents proportion in the mixes. The

  5. Diamond deposition using a planar radio frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Bozeman, S. P.; Tucker, D. A.; Stoner, B. R.; Glass, J. T.; Hooke, W. M.

    1995-06-01

    A planar radio frequency inductively coupled plasma has been used to deposit diamond onto scratched silicon. This plasma source has been developed recently for use in large area semiconductor processing and holds promise as a method for scale up of diamond growth reactors. Deposition occurs in an annulus which coincides with the area of most intense optical emission from the plasma. Well-faceted diamond particles are produced when the substrate is immersed in the plasma.

  6. Examination of Short- and Long-Range Atomic Order Nanocrystalline SiC and Diamond by Powder Diffraction Methods

    NASA Technical Reports Server (NTRS)

    Palosz, B.; Grzanka, E.; Stelmakh, S.; Gierlotka, S.; Weber, H.-P.; Proffen, T.; Palosz, W.

    2002-01-01

    The real atomic structure of nanocrystals determines unique, key properties of the materials. Determination of the structure presents a challenge due to inherent limitations of standard powder diffraction techniques when applied to nanocrystals. Alternate methodology of the structural analysis of nanocrystals (several nanometers in size) based on Bragg-like scattering and called the "apparent lattice parameter" (alp) is proposed. Application of the alp methodology to examination of the core-shell model of nanocrystals will be presented. The results of application of the alp method to structural analysis of several nanopowders were complemented by those obtained by determination of the Atomic Pair Distribution Function, PDF. Based on synchrotron and neutron diffraction data measured in a large diffraction vector of up to Q = 25 Angstroms(exp -1), the surface stresses in nanocrystalline diamond and SiC were evaluated.

  7. Analyses of Diamond Wire Sawn Wafers: Effect of Various Cutting Parameters

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

    Sopori, Bhushan; Basnyat, Prakash; Devayajanam, Srinivas

    We have evaluated surface characteristics of diamond wire cut (DWC) wafers sawn under a variety of cutting parameters. These characteristics include surface roughness, spatial frequencies of surface profiles, phase changes, damage depth, and lateral non-uniformities in the surface damage. Various cutting parameters investigated are: wire size, diamond grit size, reciprocating frequency, feed rate, and wire usage. Spatial frequency components of surface topography/roughness are influenced by individual cutting parameters as manifested by distinct peaks in the Fourier transforms of the Dektak profiles. The depth of damage is strongly controlled by diamond grit size and wire usage and to a smaller degreemore » by the wire size.« less

  8. On diamond, graphitic and amorphous carbons in primitive extraterrestrial solar system materials

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1990-01-01

    Carbon is among the most abundant elements in the universe and carbon chemistry in meteorites and comets is an important key to understanding many Solar System and interstellar processes. Yet, the mineralogical properties and interrelations between various structural forms of elemental carbon remain ambiguous. Crystalline elemental carbons include rhombohedral graphite, hexagonal graphite, cubic diamond, hexagonal diamond (i.e., lonsdaleite or carbon-2H) and chaoite. Elemental carbon also occurs as amorphous carbon and poorly graphitized (or turbostratic) carbon but of all the forms of elemental carbon only graphite is stable under physical conditions that prevail in small Solar System bodies and in the interstellar medium. The recent discovery of cubic diamond in carbonaceous chondrites and hexagonal diamond in chondritic interplanetary dust particles (IDPs) have created a renewed interest in the crystalline elemental carbons that were not formed by shock processes on a parent body. Another technique, Raman spectroscopy, confirms a widespread occurrence of disordered graphite in the Allende carbonaceous chondrite and in chondritic IDPs. Elemental carbons have also been identified by their characteristic K-edge features in electron energy loss spectra (EELS). However, the spectroscopic data do not necessarily coincide with those obtained by selected area electron diffraction (SAED). In order to interpret these data in terms of rational crystalline structures, it may be useful to consider the principles underlying electron diffraction and spectroscopic analyses. Electron diffraction depends on electron scattering, on the type of atom and the distance between atoms in a crystal lattice. Spectroscopic data are a function of the type of atom and the energy of bonds between atoms. Also, SAED is a bulk sampling technique when compared to techniques such as Raman spectroscopy or EELS. Thus, it appears that combined analyses provide contradictory results and that amorphous

  9. Poly (lactic-co-glycolic acid) particles prepared by microfluidics and conventional methods. Modulated particle size and rheology.

    PubMed

    Perez, Aurora; Hernández, Rebeca; Velasco, Diego; Voicu, Dan; Mijangos, Carmen

    2015-03-01

    Microfluidic techniques are expected to provide narrower particle size distribution than conventional methods for the preparation of poly (lactic-co-glycolic acid) (PLGA) microparticles. Besides, it is hypothesized that the particle size distribution of poly (lactic-co-glycolic acid) microparticles influences the settling behavior and rheological properties of its aqueous dispersions. For the preparation of PLGA particles, two different methods, microfluidic and conventional oil-in-water emulsification methods were employed. The particle size and particle size distribution of PLGA particles prepared by microfluidics were studied as a function of the flow rate of the organic phase while particles prepared by conventional methods were studied as a function of stirring rate. In order to study the stability and structural organization of colloidal dispersions, settling experiments and oscillatory rheological measurements were carried out on aqueous dispersions of PLGA particles with different particle size distributions. Microfluidics technique allowed the control of size and size distribution of the droplets formed in the process of emulsification. This resulted in a narrower particle size distribution for samples prepared by MF with respect to samples prepared by conventional methods. Polydisperse samples showed a larger tendency to aggregate, thus confirming the advantages of microfluidics over conventional methods, especially if biomedical applications are envisaged. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Role of high microwave power on growth and microstructure of thick nanocrystalline diamond films: A comparison with large grain polycrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Tang, C. J.; Fernandes, A. J. S.; Girão, A. V.; Pereira, S.; Shi, Fa-Nian; Soares, M. R.; Costa, F.; Neves, A. J.; Pinto, J. L.

    2014-03-01

    In this work, we study the growth habit of nanocrystalline diamond (NCD) films by exploring the very high power regime, up to 4 kW, in a 5 kW microwave plasma chemical vapour deposition (MPCVD) reactor, through addition of a small amount of nitrogen and oxygen (0.24%) into 4% CH4 in H2 plasma. The coupled effect of high microwave power and substrate temperature on NCD growth behaviour is systematically investigated by varying only power, while fixing the remaining operating parameters. When the power increases from 2 kW to 4 kW, resulting also in rise of the Si substrate temperature higher than 150 °C, the diamond films obtained maintain the NCD habit, while the growth rate increases significantly. The highest growth rate of 4.6 μm/h is achieved for the film grown at 4 kW, which represents a growth rate enhancement of about 15 times compared with that obtained when using 2 kW power. Possible factors responsible for such remarkable growth rate enhancement of the NCD films are discussed. The evolution of NCD growth characteristics such as morphology, microstructure and texture is studied by growing thick films and comparing it with that of large grain polycrystalline (PCD) films. One important characteristic of the NCD films obtained, in contrast to PCD films, is that irrespective of deposition time (i.e. film thickness), their grain size and surface roughness remain in the nanometer range throughout the growth. Finally, based on our present and previous experimental results, a potential parameter window is established for fast growth of NCD films under high power conditions.

  11. Determining size-specific emission factors for environmental tobacco smoke particles

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

    Klepeis, Neil E.; Apte, Michael G.; Gundel, Lara A.

    Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured everymore » minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1-2+ micrometer diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01-1+ micrometer diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m{sup 3} chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 hours after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle emission factors were fit with log-normal distributions, yielding an average mass median diameter of 0.2 micrometers and an average geometric standard deviation of 2.3 with no systematic differences between cigars and cigarettes. The equivalent total particle emission rate, obtained integrating each size distribution, was 0.2-0.7 mg/min for cigars and 0.7-0.9 mg/min for cigarettes.« less

  12. Tulane/Xavier Vaccine Peptide Program

    DTIC Science & Technology

    2013-07-01

    include a dry powder formulation, microemulsions , nonspherical liposomes, ceramic shell vesicles, and nanometer-sized silk particles. Nasal...pulmonary delivery: dry powder formulation, microemulsions , nonspherical liposomes, ceramic shell vesicles, and nanometer-sized silk particles. (3) Confirm...include a dry powder formulation, microemulsions , nonspherical liposomes, ceramic shell vesicles, and nanometer-sized silk particles. Nasal

  13. Particle sizes in slash fire smoke.

    Treesearch

    David V. Sandberg; Robert E. Martin

    1975-01-01

    Particulate emissions are the most objectionable atmospheric contaminant from forest burning. Little is known of the particulate sizes, and this research was done under laboratory conditions to obtain particle size information. Comments are made concerning techniques for future work in this field.

  14. Relationship Between Cirrus Particle Size and Cloud Top Temperature

    NASA Technical Reports Server (NTRS)

    Han, Qingyuan; Chou, Joyce; Welch, Ronald M.

    1997-01-01

    The relationship between cirrus particle size and cloud top temperature is surveyed on a near-global scale. The cirrus particle size is retrieved assuming ice crystals are hexagonal columns and the cloud top temperature and the radiances in channel 1 and 3 of AVHRR used to retrieve ice particle sizes are from ISCCP product. The results show that for thick clouds over North America, the relation between particle size and cloud top temperature is consistent with a summary of this relationship based on aircraft measurement over that region for thick clouds. However, this relationship is not universal for other regions especially for for tropical zone, which has been found by other in situ measurements.

  15. Mobility particle size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

    NASA Astrophysics Data System (ADS)

    Wiedensohler, A.; Birmili, W.; Nowak, A.; Sonntag, A.; Weinhold, K.; Merkel, M.; Wehner, B.; Tuch, T.; Pfeifer, S.; Fiebig, M.; Fjäraa, A. M.; Asmi, E.; Sellegri, K.; Depuy, R.; Venzac, H.; Villani, P.; Laj, P.; Aalto, P.; Ogren, J. A.; Swietlicki, E.; Williams, P.; Roldin, P.; Quincey, P.; Hüglin, C.; Fierz-Schmidhauser, R.; Gysel, M.; Weingartner, E.; Riccobono, F.; Santos, S.; Grüning, C.; Faloon, K.; Beddows, D.; Harrison, R.; Monahan, C.; Jennings, S. G.; O'Dowd, C. D.; Marinoni, A.; Horn, H.-G.; Keck, L.; Jiang, J.; Scheckman, J.; McMurry, P. H.; Deng, Z.; Zhao, C. S.; Moerman, M.; Henzing, B.; de Leeuw, G.; Löschau, G.; Bastian, S.

    2012-03-01

    Mobility particle size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers) or SMPS (Scanning Mobility Particle Sizers) have found a wide range of applications in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards and guidelines with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. Technical standards were developed for a minimum requirement of mobility size spectrometry to perform long-term atmospheric aerosol measurements. Technical recommendations include continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyzer. We compared commercial and custom-made inversion routines to calculate the particle number size distributions from the measured electrical mobility distribution. All inversion routines are comparable within few per cent uncertainty for a given set of raw data. Furthermore, this work summarizes the results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research) and ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) to determine present uncertainties especially of custom-built mobility particle size spectrometers. Under controlled laboratory conditions, the particle number size distributions from 20 to 200 nm determined by mobility particle size spectrometers of different design are within an uncertainty range of around ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. For particles larger than 200 nm, the uncertainty range increased to 30%, which could not be explained. The network reference mobility spectrometers with identical design agreed within ±4% in the peak particle number concentration

  16. Proposal for ultrasmall deep ultraviolet diamond Raman nanolaser

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Hyon; Choe, Song-Hyok

    2016-10-01

    We propose diamond nanoparticle Raman laser operating in the spectral range of deep ultraviolet. High Raman gain and low cavity loss of diamond nanoparticles enable low-threshold Raman lasing. Based on the coupled-mode theory, we numerically study its lasing dynamics. For the diamond nanoparticle with a radius of about 130 nm, the lasing threshold energy is below 10 pJ for a pump spot size of 1 μm.

  17. Are diamond nanoparticles cytotoxic?

    PubMed

    Schrand, Amanda M; Huang, Houjin; Carlson, Cataleya; Schlager, John J; Omacr Sawa, Eiji; Hussain, Saber M; Dai, Liming

    2007-01-11

    Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types.

  18. Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium.

    PubMed

    Zakhari, Monica E A; Anderson, Patrick D; Hütter, Markus

    2017-07-01

    Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012)1359-664010.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1%. The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

  19. Effect of particle-size dynamics on properties of dense spongy-particle systems: Approach towards equilibrium

    NASA Astrophysics Data System (ADS)

    Zakhari, Monica E. A.; Anderson, Patrick D.; Hütter, Markus

    2017-07-01

    Open-porous deformable particles, often envisaged as sponges, are ubiquitous in biological and industrial systems (e.g., casein micelles in dairy products and microgels in cosmetics). The rich behavior of these suspensions is owing to the elasticity of the supporting network of the particle, and the viscosity of permeating solvent. Therefore, the rate-dependent size change of these particles depends on their structure, i.e., the permeability. This work aims at investigating the effect of the particle-size dynamics and the underlying particle structure, i.e., the particle permeability, on the transient and long-time behavior of suspensions of spongy particles in the absence of applied deformation, using the dynamic two-scale model developed by Hütter et al. [Farad. Discuss. 158, 407 (2012), 10.1039/c2fd20025b]. In the high-density limit, the transient behavior is found to be accelerated by the particle-size dynamics, even at average size changes as small as 1 % . The accelerated dynamics is evidenced by (i) the higher short-time diffusion coefficient as compared to elastic-particle systems and (ii) the accelerated formation of the stable fcc crystal structure. Furthermore, after long times, the particle-size dynamics of spongy particles is shown to result in lower stationary values of the energy and normal stresses as compared to elastic-particle systems. This dependence of the long-time behavior of these systems on the permeability, that essentially is a transport coefficient and hence must not affect the equilibrium properties, confirms that full equilibration has not been reached.

  20. Diffractive optics for particle velocimetry and sizing

    NASA Technical Reports Server (NTRS)

    Wilson, D. W.; Gogna, P. K.; Chacon, R. J.; Muller, R. E.; Fourguette, D.; Modarress, D.; Taugwalder, F.; Svitek, P.; Gharib, M.

    2002-01-01

    Beam-shaping diffractive optical elements are used to create structured light patterns in fluid flows. Particle scattering results in detected signals that can be used to determine the particle size and velocity.

  1. Radiation Halos, a Rare Microstructure in Diamonds From the Central African Republic

    NASA Astrophysics Data System (ADS)

    Vicenzi, E. P.; Heaney, P. J.; Snyder, K.; Armstrong, L.

    2002-05-01

    The geochemical characterization of bulk diamonds and associated inclusions as a tool for determining provenance carries significant inherent limitations. Isotopic and trace element signatures are imparted within the mantle during diamond growth; hence, discriminating crystals from a particular region on the Earth's surface on this basis is difficult at best, and impossible (using current technologies) in many cases. In contrast, rare diamond characteristics may provide a partial solution for recognizing stones from a limited number of localities. Here we discuss an analysis of radiation halos in alluvially deposited polycrystalline diamonds (carbonados) from the Central African Republic (CAR). Large amounts of implanted Xe and Kr, as well as isotopic ratios of those elements consistent with fission, in carbonado strongly suggest that diamond crystallization took place in the presence of significant quantities of uranium [1]. Such ionizing radiation ultimately results in the loss of periodicity of the diamond structure. Crystallographically damaged areas produce fewer photons in cathodoluminescence microscopy, and therefore, the metamict regions resulting from point source radiation in diamond can be visualized on the scale of ~1-25 micrometers [2]. Because intermediate daughter products in the decay chain release alpha particles at differing energies, a ``bull's eye'' pattern is produced in 2-D by the point source radiation. Radiation haloes have been previously observed in carbonados and are thought to result from U deposition associated with fluids following diamond formation [3,4]. We have made a series of measurements of the apparent diameter of the largest circle within a damage halo. By comparing the statistical distribution of this dimension to the distribution expected for a series of circles resulting from random sectioning of mono-sized spheres, one can estimate whether the radiation resulted from one or more fluid pulses widely separated in time

  2. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

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

    O'Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed thatmore » both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.« less

  3. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: insight into particle origin and chemistry

    DOE PAGES

    Ghosal, Sutapa; Weber, Peter K.; Laskin, Alexander

    2014-01-14

    Knowledge of the spatially resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry and understanding particle reactivity and the potential environmental impact. Here, we demonstrate the application of nanometer-scale secondary ion mass spectrometry (CAMECA NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad range of particle sizes. We have used this technique to probe the spatially resolved composition of ambient particles collected during amore » field campaign in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth-resolved chemical imaging in ambient particle research. The particles that we examined in our study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location before the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen, and chlorine at the particle surface. We also observed the surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas–particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insight into their chemical history.« less

  4. Spatially resolved chemical imaging of individual atmospheric particles using nanoscale imaging mass spectrometry: Insighs into particle origin and chemistry

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

    Ghosal, Sutapa; Weber, Peter K.; Laskin, Alexander

    2014-04-21

    Knowledge of the spatially-resolved composition of atmospheric particles is essential for differentiating between their surface versus bulk chemistry, understanding particle reactivity and the potential environmental impact. We demonstrate the application of nanometer-scale secondary ion mass spectrometry (Cameca NanoSIMS 50 ion probe) for 3D chemical imaging of individual atmospheric particles without any sample pre-treatment, such as the sectioning of particles. Use of NanoSIMS depth profile analysis enables elemental mapping of particles with nanometer spatial resolution over a broad of range of particle sizes. We have used this technique to probe spatially resolved composition of ambient particles collected during a field campaignmore » in Mexico City. Particles collected during this campaign have been extensively characterized in the past using other particle analysis techniques and hence offer a unique opportunity for exploring the utility of depth resolved chemical imaging in ambient particle research. 1 Particles examined in this study include those collected during a pollution episode related to urban waste incineration as well as background particles from the same location prior to the episode. Particles from the pollution episode show substantial intra-particle compositional variability typical of particles resulting from multiple emission sources. In contrast, the background particles have relatively homogeneous compositions with enhanced presence of nitrogen, oxygen and chlorine at the particle surface. The observed surface enhancement of nitrogen and oxygen species is consistent with the presence of surface nitrates resulting from gas-particle heterogeneous interactions and is indicative of atmospheric ageing of the particles. The results presented here illustrate 3D characterization of ambient particles for insights into their chemical history.« less

  5. Dense plasma chemistry of hydrocarbons at conditions relevant to planetary interiors and inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Kraus, Dominik

    2017-10-01

    Carbon-hydrogen demixing and subsequent diamond precipitation has been predicted to strongly participate in shaping the internal structure and evolution of icy giant planets like Neptune and Uranus. The very same dense plasma chemistry is also a potential concern for CH plastic ablator materials in inertial confinement fusion (ICF) experiments where similar conditions are present during the first compression stage of the imploding capsule. Here, carbon-hydrogen demixing may enhance the hydrodynamic instabilities occurring in the following compression stages. First experiments applying dynamic compression and ultrafast in situ X-ray diffraction at SLAC's Linac Coherent Light Source demonstrated diamond formation from polystyrene (CH) at 150 GPa and 5000 K. Very recent experiments have now investigated the influence of oxygen, which is highly abundant in icy giant planets on the phase separation process. Compressing PET (C5H4O2) and PMMA(C5H8O2), we find again diamond formation at pressures above 150 GPa and temperatures of several thousand kelvins, showing no strong effect due to the presence of oxygen. Thus, diamond precipitation deep inside icy giant planets seems very likely. Moreover, small-angle X-ray scattering (SAXS) was added to the platform, which determines an upper limit for the diamond particle size, while the width of the diffraction features provides a lower limit. We find that diamond particles of several nanometers in size are formed on a nanosecond timescale. Finally, spectrally resolved X-ray scattering is used to scale amorphous diffraction signals and allows for determining the amount of carbon-hydrogen demixing inside the compressed samples even if no crystalline diamond is formed. This whole set of diagnostics provides unprecedented insights into the nanosecond kinetics of dense plasma chemistry.

  6. Method of producing submicron size particles and product produced thereby

    DOEpatents

    Bourne, R.S.; Eichman, C.C.; Welbon, W.W.

    1988-05-11

    Submicron size particles are produced by using a sputtering process to deposit particles into a liquid. The liquid is processed to recover the particles therefrom, and the particles have sizes in the range of twenty to two hundred Angstroms. Either metallic or non-metallic particles can be produced, and the metallic particles can be used in ''metallic inks.'' 4 figs.

  7. Chromate content versus particle size for aircraft paints.

    PubMed

    LaPuma, Peter T; Rhodes, Brian S

    2002-12-01

    Many industries rely on the corrosion inhibiting properties of chromate-containing primer paints to protect metal from oxidation. However, chromate contains hexavalent chromium (Cr(6+)), a known human carcinogen. The concentration of Cr(6+) as a function of paint particle size has important implications to worker health and environmental release from paint facilities. This research examines Cr(6+) content as a function of particle size for three types of aircraft primer paints: solvent-based epoxy-polyamide, water-based epoxy-polyamide, and solvent-based polyurethane. Cascade impactors were used to collect and separate paint particles based on their aerodynamic diameter, from 0.7 to 34.1 microm. The mass of the dry paint collected at each stage was determined and an atomic absorption spectrometer was used to analyze for Cr(6+) content. For all three paints, particles less than 7.0 microm contained disproportionately less Cr(6+) per mass of dry paint than larger particles, and the Cr(6+)concentration decreased substantially as particle size decreased. The smallest particles, 0.7 to 1.0 microm, contained approximately 10% of the Cr(6+) content, per mass of dry paint, compared to particles larger than 7.0 microm. The paint gun settings of air to paint ratio was found to have no influence on the Cr(6+) bias.

  8. Effect of Cobalt Particle Size on Acetone Steam Reforming

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

    Sun, Junming; Zhang, He; Yu, Ning

    2015-06-11

    Carbon-supported cobalt nanoparticles with different particle sizes were synthesized and characterized by complementary characterization techniques such as X-ray diffraction, N-2 sorption, acetone temperature-programmed desorption, transmission electron microscopy, and CO chemisorption. Using acetone steam reforming reaction as a probe reaction, we revealed a volcano-shape curve of the intrinsic activity (turnover frequency of acetone) and the CO2 selectivity as a function of the cobalt particle size with the highest activity and selectivity observed at a particle size of approximately 12.8nm. Our results indicate that the overall performance of acetone steam reforming is related to a combination of particle-size-dependent acetone decomposition, water dissociation,more » and the oxidation state of the cobalt nanoparticles.« less

  9. Deliquescence and efflorescence of small particles.

    PubMed

    McGraw, Robert; Lewis, Ernie R

    2009-11-21

    We examine size-dependent deliquescence/efflorescence phase transformation for particles down to several nanometers in size. Thermodynamic properties of inorganic salt particles, coated with aqueous solution layers of varying thickness and surrounded by vapor, are analyzed. A thin layer criterion (TLC) is introduced to define a limiting deliquescence relative humidity (RH(D)) for small particles. This requires: (1) equality of chemical potentials between salt in an undissolved core, and thin adsorbed solution layer, and (2) equality of chemical potentials between water in the thin layer and vapor phase. The usual bulk deliquescence conditions are recovered in the limit of large dry particle size. Nanosize particles are found to deliquesce at relative humidity just below the RH(D) on crossing a nucleation barrier, located at a critical solution layer thickness. This barrier vanishes precisely at the RH(D) defined by the TLC. Concepts and methods from nucleation theory including the kinetic potential, self-consistent nucleation theory, nucleation theorems, and the Gibbs dividing surface provide theoretical foundation and point to unifying features of small particle deliquescence/efflorescence processes. These include common thermodynamic area constructions, useful for interpretation of small particle water uptake measurements, and a common free-energy surface, with constant RH cross sections describing deliquescence and efflorescence related through the nucleation theorem.

  10. Influence of particle size on Cutting Forces and Surface Roughness in Machining of B4Cp - 6061 Aluminium Matrix Composites

    NASA Astrophysics Data System (ADS)

    Hiremath, Vijaykumar; Badiger, Pradeep; Auradi, V.; Dundur, S. T.; Kori, S. A.

    2016-02-01

    Amongst advanced materials, metal matrix composites (MMC) are gaining importance as materials for structural applications in particular, particulate reinforced aluminium MMCs have received considerable attention due to their superior properties such as high strength to weight ratio, excellent low-temperature performance, high wear resistance, high thermal conductivity. The present study aims at studying and comparing the machinability aspects of B4Cp reinforced 6061Al alloy metal matrix composites reinforced with 37μm and 88μm particulates produced by stir casting method. The micro structural characterization of the prepared composites is done using Scanning Electron Microscopy equipped with EDX analysis (Hitachi Su-1500 model) to identify morphology and distribution of B4C particles in the 6061Al matrix. The specimens are turned on a conventional lathe machine using a Polly crystalline Diamond (PCD) tool to study the effect of particle size on the cutting forces and the surface roughness under varying machinability parameters viz., Cutting speed (29-45 m/min.), Feed rate (0.11-0.33 mm/rev.) and depth of cut (0.5-1mm). Results of micro structural characterization revealed fairly uniform distribution of B4C particles (in both cases i.e., 37μm and 88μm) in 6061Al matrix. The surface roughness of the composite is influenced by cutting speed. The feed rate and depth of cut have a negative influence on surface roughness. The cutting forces decreased with increase in cutting speed whereas cutting forces increased with increase in feed and depth of cut. Higher cutting forces are noticed while machining Al6061 base alloy compared to reinforced composites. Surface finish is high during turning of the 6061Al base alloy and surface roughness is high with 88μm size particle reinforced composites. As the particle size increases Surface roughness also increases.

  11. Targeted and Nontargeted α-Particle Therapies.

    PubMed

    McDevitt, Michael R; Sgouros, George; Sofou, Stavroula

    2018-06-04

    α-Particle irradiation of cancerous tissue is increasingly recognized as a potent therapeutic option. We briefly review the physics, radiobiology, and dosimetry of α-particle emitters, as well as the distinguishing features that make them unique for radiopharmaceutical therapy. We also review the emerging clinical role of α-particle therapy in managing cancer and recent studies on in vitro and preclinical α-particle therapy delivered by antibodies, other small molecules, and nanometer-sized particles. In addition to their unique radiopharmaceutical characteristics, the increased availability and improved radiochemistry of α-particle radionuclides have contributed to the growing recent interest in α-particle radiotherapy. Targeted therapy strategies have presented novel possibilities for the use of α-particles in the treatment of cancer. Clinical experience has already demonstrated the safe and effective use of α-particle emitters as potent tumor-selective drugs for the treatment of leukemia and metastatic disease.

  12. Targeted and Nontargeted α-Particle Therapies

    PubMed Central

    McDevitt, Michael R.; Sgouros, George; Sofou, Stavroula

    2018-01-01

    α-Particle irradiation of cancerous tissue is increasingly recognized as a potent therapeutic option. We briefly review the physics, radiobiology, and dosimetry of α-particle emitters, as well as the distinguishing features that make them unique for radiopharmaceutical therapy. We also review the emerging clinical role of α-particle therapy in managing cancer and recent studies on in vitro and preclinical α-particle therapy delivered by antibodies, other small molecules, and nanometer-sized particles. In addition to their unique radiopharmaceutical characteristics, the increased availability and improved radiochemistry of α-particle radionuclides have contributed to the growing recent interest in α-particle radiotherapy. Targeted therapy strategies have presented novel possibilities for the use of α-particles in the treatment of cancer. Clinical experience has already demonstrated the safe and effective use of α-particle emitters as potent tumor-selective drugs for the treatment of leukemia and metastatic disease. PMID:29345977

  13. Size Dependent Elemental Composition of Road-Associated Particles

    PubMed Central

    McKenzie, Erica R.; Wong, Carol M.; Green, Peter G.; Kayhanian, Masoud; Young, Thomas M.

    2009-01-01

    Stormwater particles often provide transport for metals and other contaminants, however only larger particles are effectively removed by typical best management practices. Fine particles and their associated constituents are more likely to reach receiving waters; this merits further investigation regarding the metal contribution of fine (dp<10 μm) and very fine (dp <1.5 μm) particles. Road associated particles were collected by vacuuming a road surface and by collecting highway stormwater runoff. A cell sorter was employed to sort road associated particles into four size ranges: 0.1–0.3, 0.3–0.5, 0.5–1.0, and 1.0–1.5 μm. These very fine particles, along with six particle size ranges (total range <2–63 μm) separated using a settling column, were analyzed for Al, Mn, Fe, Cr, Ni, Cu, Zn, and Pb using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Enrichment factors (EFs), calculated using Al as a basis to represent crustal contributions, were similar for the vacuumed road dust and the stormwater runoff. Fe and Mn were minimally depleted (0.1x) or near unity for all size ranges (Fe EF range 0.01–3.7; Mn EF range 0.02–10.6). Cr, Ni, Cu, Zn, and Pb were moderately (10x) to considerably (>100x) enriched for most size ranges; these metals were most enriched in the very fine fractions (max EF~4900 in Zn, 0.1–0.3 μm). Based on this preliminary study, a cell sorter is an acceptable means of fractionating aqueous particles of diameter 0.1–1.5 μm. In spite of their minimal relative mass contribution, the very fine particles are environmentally relevant due to their mobility and enrichment in potentially toxic metals.. PMID:18433840

  14. Seed particle response and size characterization in high speed flows

    NASA Technical Reports Server (NTRS)

    Rudoff, Roger C.; Bachalo, William D.

    1991-01-01

    The response of seed particles ranging between 0.7 and 8.7 micron is determined using a phase Doppler particle analyzer which simultaneously measures particle size and velocity. The stagnant seed particles are entrained into a high speed free jet at velocities ranging from 40 to 300 m/s. The size-mean axial velocity correlation and size-rms velocity correlations are used to determine the particle response to the sudden acceleration. It was determined that at the lower speeds, seed particles up to approximately 5 microns are adequate, but as velocities approach 300 m/s only particles on the order of one micron are suitable. The ability to determine size and velocity simultaneously is essential if seeding with polydispersions is used since it allows the rejection of data which will not accurately represent the flow field.

  15. Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

    NASA Astrophysics Data System (ADS)

    Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

    2015-02-01

    Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

  16. PROCEDURE FOR DETERMINATION OF SEDIMENT PARTICLE SIZE (GRAIN SIZE)

    EPA Science Inventory

    Sediment quality and sediment remediation projects have become a high priority for USEPA. Sediment particle size determinations are used in environmental assessments for habitat characterization, chemical normalization, and partitioning potential of chemicals. The accepted met...

  17. Stochastic many-particle model for LFP electrodes

    NASA Astrophysics Data System (ADS)

    Guhlke, Clemens; Gajewski, Paul; Maurelli, Mario; Friz, Peter K.; Dreyer, Wolfgang

    2018-02-01

    In the framework of non-equilibrium thermodynamics, we derive a new model for many-particle electrodes. The model is applied to LiFePO4 (LFP) electrodes consisting of many LFP particles of nanometer size. The phase transition from a lithium-poor to a lithium-rich phase within LFP electrodes is controlled by both different particle sizes and surface fluctuations leading to a system of stochastic differential equations. An explicit relation between battery voltage and current controlled by the thermodynamic state variables is derived. This voltage-current relation reveals that in thin LFP electrodes lithium intercalation from the particle surfaces into the LFP particles is the principal rate-limiting process. There are only two constant kinetic parameters in the model describing the intercalation rate and the fluctuation strength, respectively. The model correctly predicts several features of LFP electrodes, viz. the phase transition, the observed voltage plateaus, hysteresis and the rate-limiting capacity. Moreover we study the impact of both the particle size distribution and the active surface area on the voltage-charge characteristics of the electrode. Finally we carefully discuss the phase transition for varying charging/discharging rates.

  18. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2001-01-01

    An overview of the industrial diamond industry is provided. More than 90 percent of the industrial diamond consumed in the U.S. and the rest of the world is manufactured diamond. Ireland, Japan, Russia, and the U.S. produce 75 percent of the global industrial diamond output. In 2000, the U.S. was the largest market for industrial diamond. Industrial diamond applications, prices for industrial diamonds, imports and exports of industrial diamonds, the National Defense Stockpile of industrial diamonds, and the outlook for the industrial diamond market are discussed.

  19. Note: Evaluation of slurry particle size analyzers for chemical mechanical planarization process

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

    Jang, Sunjae; Kulkarni, Atul; Qin, Hongyi

    In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution bymore » analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements.« less

  20. Characteristics of dimethylaminium and trimethylaminium in atmospheric particles ranging from supermicron to nanometer sizes over eutrophic marginal seas of China and oligotrophic open oceans.

    PubMed

    Yu, Peiran; Hu, Qingjing; Li, Kai; Zhu, Yujiao; Liu, Xiaohuan; Gao, Huiwang; Yao, Xiaohong

    2016-12-01

    In this study, we characterized dimethylaminium (DMA + ) and trimethylaminium (TMA + ) in size-segregated atmospheric particles during three cruise campaigns in the marginal seas of China and one cruise campaign mainly in the northwest Pacific Ocean (NWPO). An 14-stage nano-MOUDI sampler was utilized for sampling atmospheric particles ranging from 18μm to 0.010μm. Among the four cruise campaigns, the highest concentrations of DMA + and TMA + in PM 10 were observed over the South Yellow Sea (SYS) in August 2015, i.e., 0.76±0.12nmolm -3 for DMA + (average value±standard deviation) and 0.93±0.13nmolm -3 for TMA + . The lowest values were observed over the NWPO in April 2015, i.e., 0.28±0.16nmolm -3 for DMA + and 0.22±0.12nmolm -3 for TMA + . In general, size distributions of the two ions exhibited a bi-modal pattern, i.e., one mode at 0.01-0.1μm and the other at 0.1-1.8μm. The two ions' mode at 0.01-0.1μm was firstly observed. The mode was largely enhanced in samples collected over the SYS in August 2015, leading to high mole ratios of (DMA + +TMA + )/NH 4 + in PM 0.1 (0.4±0.8, median value±standard deviation) and the ions' concentrations in PM 0.1 accounting for ~10% and ~40% of their corresponding concentrations in PM 10 . This implied that (DMA + +TMA + ) likely played an important role in neutralizing acidic species in the smaller particles. Using SO 4 2- , NO 3 - and NH 4 + as references, we confirm that the elevated concentrations of DMA + and TMA + in the 0.01-0.1μm size range were probably real signals rather than sampling artifacts. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Micro-architecture embedding ultra-thin interlayer to bond diamond and silicon via direct fusion

    NASA Astrophysics Data System (ADS)

    Kim, Jong Cheol; Kim, Jongsik; Xin, Yan; Lee, Jinhyung; Kim, Young-Gyun; Subhash, Ghatu; Singh, Rajiv K.; Arjunan, Arul C.; Lee, Haigun

    2018-05-01

    The continuous demand on miniaturized electronic circuits bearing high power density illuminates the need to modify the silicon-on-insulator-based chip architecture. This is because of the low thermal conductivity of the few hundred nanometer-thick insulator present between the silicon substrate and active layers. The thick insulator is notorious for releasing the heat generated from the active layers during the operation of devices, leading to degradation in their performance and thus reducing their lifetime. To avoid the heat accumulation, we propose a method to fabricate the silicon-on-diamond (SOD) microstructure featured by an exceptionally thin silicon oxycarbide interlayer (˜3 nm). While exploiting the diamond as an insulator, we employ spark plasma sintering to render the silicon directly fused to the diamond. Notably, this process can manufacture the SOD microarchitecture via a simple/rapid way and incorporates the ultra-thin interlayer for minute thermal resistance. The method invented herein expects to minimize the thermal interfacial resistance of the devices and is thus deemed as a breakthrough appealing to the current chip industry.

  2. Particle Size Distribution in Aluminum Manufacturing Facilities

    PubMed Central

    Liu, Sa; Noth, Elizabeth M.; Dixon-Ernst, Christine; Eisen, Ellen A.; Cullen, Mark R.; Hammond, S. Katharine

    2015-01-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM2.5 measured by PMI was compared to PM2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM1.0) and quasi-ultrafine (PM0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM2.5 versus MiniMOUDI_PM2.5 was 1.03 mg/m3 per mg/m3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM10 which was PM1.0 or PM0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities. PMID:26478760

  3. Particle Size Distribution in Aluminum Manufacturing Facilities.

    PubMed

    Liu, Sa; Noth, Elizabeth M; Dixon-Ernst, Christine; Eisen, Ellen A; Cullen, Mark R; Hammond, S Katharine

    2014-10-01

    As part of exposure assessment for an ongoing epidemiologic study of heart disease and fine particle exposures in aluminum industry, area particle samples were collected in production facilities to assess instrument reliability and particle size distribution at different process areas. Personal modular impactors (PMI) and Minimicro-orifice uniform deposition impactors (MiniMOUDI) were used. The coefficient of variation (CV) of co-located samples was used to evaluate the reproducibility of the samplers. PM 2.5 measured by PMI was compared to PM 2.5 calculated from MiniMOUDI data. Mass median aerodynamic diameter (MMAD) and concentrations of sub-micrometer (PM 1.0 ) and quasi-ultrafine (PM 0.56) particles were evaluated to characterize particle size distribution. Most of CVs were less than 30%. The slope of the linear regression of PMI_PM 2.5 versus MiniMOUDI_PM 2.5 was 1.03 mg/m 3 per mg/m 3 (± 0.05), with correlation coefficient of 0.97 (± 0.01). Particle size distribution varied substantively in smelters, whereas it was less variable in fabrication units with significantly smaller MMADs (arithmetic mean of MMADs: 2.59 μm in smelters vs. 1.31 μm in fabrication units, p = 0.001). Although the total particle concentration was more than two times higher in the smelters than in the fabrication units, the fraction of PM 10 which was PM 1.0 or PM 0.56 was significantly lower in the smelters than in the fabrication units (p < 0.001). Consequently, the concentrations of sub-micrometer and quasi-ultrafine particles were similar in these two types of facilities. It would appear, studies evaluating ultrafine particle exposure in aluminum industry should focus on not only the smelters, but also the fabrication facilities.

  4. 'Diamond' in 3-D

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 3-D, microscopic imager mosaic of a target area on a rock called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  5. Sonochemical synthesis of silica particles and their size control

    NASA Astrophysics Data System (ADS)

    Kim, Hwa-Min; Lee, Chang-Hyun; Kim, Bonghwan

    2016-09-01

    Using an ultrasound-assisted sol-gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

  6. Characterization of N-doped polycrystalline diamond films deposited on microgrinding tools

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Ahmed, W.

    2005-10-01

    Chemical vapor deposited diamond films have many industrial applications but are assuming increasing importance in the area of microengineering, most notably in the development of diamond coated microgrinding tools. For these applications the control of structure and morphology is of critical importance. The crystallite size, orientation, surface roughness, and the degree of sp 3 character have a profound effect on the tribological properties of the films deposited. In this article, we present experimental results on the effects of nitrogen doping on the surface morphology, crystallite size, and wear of microgrinding tools. The sp 3 character optimizes at 200 ppm nitrogen, and above this value the surface becomes much smoother and crystal sizes decrease considerably. Fracture-induced wear of the diamond grain is the most important mechanism of material removal from a microgrinding tool during the grinding process. Fracture occurs as a consequence of tensile stresses induced into diamond grains by grinding forces to which they are subjected. The relationship between the wear of diamond coated grinding tools, component grinding forces, and induced stresses in the model diamond grains is described in detail. A significant correlation was found between the maximum value of tensile stress induced in the diamond grain and the appropriate wheel-wear parameter (grinding ratio). It was concluded that the magnitude of tensile stresses induced in the diamond grain by grinding forces at the rake face is the best indicator of tool wear during the grinding process.

  7. Adequacy of laser diffraction for soil particle size analysis

    PubMed Central

    Fisher, Peter; Aumann, Colin; Chia, Kohleth; O'Halloran, Nick; Chandra, Subhash

    2017-01-01

    Sedimentation has been a standard methodology for particle size analysis since the early 1900s. In recent years laser diffraction is beginning to replace sedimentation as the prefered technique in some industries, such as marine sediment analysis. However, for the particle size analysis of soils, which have a diverse range of both particle size and shape, laser diffraction still requires evaluation of its reliability. In this study, the sedimentation based sieve plummet balance method and the laser diffraction method were used to measure the particle size distribution of 22 soil samples representing four contrasting Australian Soil Orders. Initially, a precise wet riffling methodology was developed capable of obtaining representative samples within the recommended obscuration range for laser diffraction. It was found that repeatable results were obtained even if measurements were made at the extreme ends of the manufacturer’s recommended obscuration range. Results from statistical analysis suggested that the use of sample pretreatment to remove soil organic carbon (and possible traces of calcium-carbonate content) made minor differences to the laser diffraction particle size distributions compared to no pretreatment. These differences were found to be marginally statistically significant in the Podosol topsoil and Vertosol subsoil. There are well known reasons why sedimentation methods may be considered to ‘overestimate’ plate-like clay particles, while laser diffraction will ‘underestimate’ the proportion of clay particles. In this study we used Lin’s concordance correlation coefficient to determine the equivalence of laser diffraction and sieve plummet balance results. The results suggested that the laser diffraction equivalent thresholds corresponding to the sieve plummet balance cumulative particle sizes of < 2 μm, < 20 μm, and < 200 μm, were < 9 μm, < 26 μm, < 275 μm respectively. The many advantages of laser diffraction for soil particle

  8. Size-dependent elastic/inelastic behavior of enamel over millimeter and nanometer length scales.

    PubMed

    Ang, Siang Fung; Bortel, Emely L; Swain, Michael V; Klocke, Arndt; Schneider, Gerold A

    2010-03-01

    The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel's elastic/inelastic transition over four hierarchical length scales, namely: 'bulk enamel' (mm), 'multiple-rod' (10's microm), 'intra-rod' (100's nm with multiple crystallites) and finally 'single-crystallite' (10's nm with an area of approximately one hydroxyapatite crystallite). The enamel's elastic/inelastic transitions were observed at 0.4-17 GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius approximately 20 nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size approximately 2 mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed. (c) 2009 Elsevier Ltd. All rights reserved.

  9. Light Scattering by Wavelength-Sized Particles "Dusted" with Subwavelength-Sized Grains

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Mackowski, Daniel W.

    2011-01-01

    The numerically exact superposition T-matrix method is used to compute the scattering cross sections and the Stokes scattering matrix for polydisperse spherical particles covered with a large number of much smaller grains. We show that the optical effect of the presence of microscopic dust on the surfaces of wavelength-sized, weakly absorbing particles is much less significant than that of a major overall asphericity of the particle shape.

  10. A beam radiation monitor based on CVD diamonds for SuperB

    NASA Astrophysics Data System (ADS)

    Cardarelli, R.; Di Ciaccio, A.

    2013-08-01

    Chemical Vapor Deposition (CVD) diamond particle detectors are in use in the CERN experiments at LHC and at particle accelerator laboratories in Europe, USA and Japan mainly as beam monitors. Nowadays it is considered a proven technology with a very fast signal read-out and a very high radiation tolerance suitable for measurements in high radiation environment zones i.e. near the accelerators beam pipes. The specific properties of CVD diamonds make them a prime candidate for measuring single particles as well as high-intensity particle cascades, for timing measurements on the sub-nanosecond scale and for beam protection systems in hostile environments. A single-crystalline CVD (scCVD) diamond sensor, read out with a new generation of fast and high transition frequency SiGe bipolar transistor amplifiers, has been tested for an application as radiation monitor to safeguard the silicon vertex tracker in the SuperB detector from excessive radiation damage, cumulative dose and instantaneous dose rates. Test results with 5.5 MeV alpha particles from a 241Am radioactive source and from electrons from a 90Sr radioactive source are presented in this paper.

  11. Particle size and shape distributions of hammer milled pine

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

    Westover, Tyler Lott; Matthews, Austin Colter; Williams, Christopher Luke

    2015-04-01

    Particle size and shape distributions impact particle heating rates and diffusion of volatized gases out of particles during fast pyrolysis conversion, and consequently must be modeled accurately in order for computational pyrolysis models to produce reliable results for bulk solid materials. For this milestone, lodge pole pine chips were ground using a Thomas-Wiley #4 mill using two screen sizes in order to produce two representative materials that are suitable for fast pyrolysis. For the first material, a 6 mm screen was employed in the mill and for the second material, a 3 mm screen was employed in the mill. Bothmore » materials were subjected to RoTap sieve analysis, and the distributions of the particle sizes and shapes were determined using digital image analysis. The results of the physical analysis will be fed into computational pyrolysis simulations to create models of materials with realistic particle size and shape distributions. This milestone was met on schedule.« less

  12. Effect of particle size on mixing degree in dispensation.

    PubMed

    Nakamura, Hitoshi; Yanagihara, Yoshitsugu; Sekiguchi, Hiroko; Ohtani, Michiteru; Kariya, Satoru; Uchino, Katsuyoshi; Suzuki, Hiroshi; Iga, Tatsuji

    2004-03-01

    By using lactose colored with erythrocin, we examined the effect of particle size on mixing degree during the preparation of triturations with a mortar and pestle. We used powders with different distributions of particle sizes, i.e., powder that passed through 32-mesh but was trapped on a 42-mesh sieve (32/42-mesh powder), powder that passed through a 42-mesh sieve but was trapped on a 60-mesh sieve (42/60-mesh powder), powder that passed through a 60-mesh sieve but was trapped on a 100-mesh sieve (60/100-mesh powder), and powder that passes through a 100-mesh sieve (> 100-mesh powder). The mixing degree of colored powder and non-colored powder whose distribution of particle sizes was the same as that of the colored powder was excellent. The coefficient of variation (CV) value of the mixing degree was 6.08% after 40 rotations when colored powder was mixed with non-colored powder that both passed through a 100-mesh sieve. The CV value of the mixing degree was low in the case of mixing of colored and non-colored powders with different particle size distributions. After mixing, about 50% of 42/60-mesh powder had become smaller particles, whereas the distribution of particle sizes was not influenced by the mixing of 60/100-mesh powder. It was suggested that the mixing degree is affected by distribution of particle sizes. It may be important to determine the mixing degrees for drugs with narrow therapeutic ranges.

  13. 3D laser traking of a particle in 3DFM

    NASA Astrophysics Data System (ADS)

    Desai, Kalpit; Welch, Gregory; Bishop, Gary; Taylor, Russell; Superfine, Richard

    2003-11-01

    The principal goal of 3D tracking in our home-built 3D Magnetic Force Microscope is to monitor movement of the particle with respect to laser beam waist and keep the particle at the center of laser beam. The sensory element is a Quadrant Photo Diode (QPD) which captures scattering of light caused by particle motion with bandwidth up to 40 KHz. XYZ translation stage is the driver element which moves particle back in the center of the laser with accuracy of couple of nanometers and with bandwidth up to 300 Hz. Since our particles vary in size, composition and shape, instead of using a priori model we use standard system identification techniques to have optimal approximation to the relationship between particle motion and QPD response. We have developed position feedback control system software that is capable of 3-dimensional tracking of beads that are attached to cilia on living cells which are beating at up to 15Hz. We have also modeled the control system of instrument to simulate performance of 3D particle tracking for different experimental conditions. Given operational level of nanometers, noise poses a great challenge for the tracking system. We propose to use stochastic control theory approaches to increase robustness of tracking.

  14. Recent Results with CVD Diamond Trackers

    NASA Astrophysics Data System (ADS)

    Adam, W.; Bauer, C.; Berdermann, E.; Bergonzo, P.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Grigoriev, E.; Hallewell, G.; Hall-Wilton, R.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Karl, C.; Kass, R.; Knöpfle, K. T.; Krammer, M.; Logiudice, A.; Lu, R.; Manfredi, P. F.; Manfredotti, C.; Marshall, R. D.; Meier, D.; Mishina, M.; Oh, A.; Pan, L. S.; Palmieri, V. G.; Pernicka, M.; Peitz, A.; Pirollo, S.; Polesello, P.; Pretzl, K.; Procario, M.; Re, V.; Riester, J. L.; Roe, S.; Roff, D.; Rudge, A.; Runolfsson, O.; Russ, J.; Schnetzer, S.; Sciortino, S.; Speziali, V.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trawick, M.; Trischuk, W.; Vittone, E.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; White, C.; Ziock, H.; Zoeller, M.; RD42 Collaboration

    1999-08-01

    We present recent results on the use of Chemical Vapor Deposition (CVD) diamond microstrip detectors for charged particle tracking. A series of detectors was fabricated using 1 x 1 cm 2 diamonds. Good signal-to-noise ratios were observed using both slow and fast readout electronics. For slow readout electronics, 2 μs shaping time, the most probable signal-to-noise ratio was 50 to 1. For fast readout electronics, 25 ns peaking time, the most probable signal-to-noise ratio was 7 to 1. Using the first 2 x 4 cm 2 diamond from a production CVD reactor with slow readout electronics, the most probable signal-to-noise ratio was 23 to 1. The spatial resolution achieved for the detectors was consistent with the digital resolution expected from the detector pitch.

  15. Phase diagram of carbon and the factors limiting the quantity and size of natural diamonds

    NASA Astrophysics Data System (ADS)

    Blank, Vladimir D.; Churkin, Valentin D.; Kulnitskiy, Boris A.; Perezhogin, Igor A.; Kirichenko, Alexey N.; Denisov, Viktor N.; Erohin, Sergey V.; Sorokin, Pavel B.; Popov, Mikhail Yu

    2018-03-01

    Phase diagrams of carbon, and those focusing on the graphite-to-diamond transitional conditions in particular, are of great interest for fundamental and applied research. The present study introduces a number of experiments carried out to convert graphite under high-pressure conditions, showing a formation of stable phase of fullerene-type onions cross-linked by sp3-bonds in the 55-115 GPa pressure range instead of diamonds formation (even at temperature 2000-3000 K) and the already formed diamonds turn into carbon onions. Our results refute the widespread idea that diamonds can form at any pressure from 2.2 to 1000 GPa. The phase diagram built within this study allows us not only to explain the existing numerous experimental data on the formation of diamond from graphite, but also to make assumptions about the conditions of its growth in Earth’s crust.

  16. The Size of Gelatin Sponge Particles: Differences with Preparation Method

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

    Katsumori, Tetsuya, E-mail: katsumo@eurus.dti.ne.jp; Kasahara, Toshiyuki

    2006-12-15

    Purpose. To assess whether the size distribution of gelatin sponge particles differed according to the method used to make them and the type of original sheet. Methods. Gelatin sponge particles of approximately 1-1.5 x 1-1.5 x 2 mm were made from either Spongel or Gelfoam sheets by cutting with a scalpel and scissors. Particles were also made of either Spongel or Gelfoam sheets by pumping with two syringes and a three-way stopcock. The size distribution of the particles in saline was compared among the groups. Results. (1) Cutting versus pumping: When Spongel was used, cutting produced lower rates of smallermore » particles {<=}500 {mu}m and larger particles >2000 {mu}m compared with pumping back and forth 30 times (1.1% vs 37.6%, p < 0.0001; 2.2% vs 14.4%, p = 0.008). When Gelfoam was used, cutting produced lower rates of smaller and larger particles compared with pumping (8.5% vs 20.4%, p = 0.1809; 0% vs 48.1%, p < 0.0001). (2) Spongel versus Gelfoam: There was no significant difference in the size distribution of the particles between Spongel and Gelfoam (p = 0.2002) when cutting was used. Conclusion. The size distribution of gelatin sponge particles differed according to the method used to make them. More uniform particle sizes can be achieved by cutting than by pumping.« less

  17. Size distribution spectrum of noninertial particles in turbulence

    NASA Astrophysics Data System (ADS)

    Saito, Izumi; Gotoh, Toshiyuki; Watanabe, Takeshi

    2018-05-01

    Collision-coalescence growth of noninertial particles in three-dimensional homogeneous isotropic turbulence is studied. Smoluchowski's coagulation equation describes the evolution of the size distribution of particles in this system. By applying a methodology based on turbulence theory, the equation is shown to have a steady-state solution, which corresponds to the Kolmogorov-type power-law spectrum. Direct numerical simulations of turbulence and Lagrangian particles are conducted. The result shows that the size distribution in a statistically steady state agrees accurately with the theoretical prediction.

  18. Measurement of nonvolatile particle number size distribution

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2016-01-01

    An experimental methodology was developed to measure the nonvolatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a nonvolatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol (OA; 40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a nonvolatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type of OA

  19. 'Diamond Jenness': Before the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the rock called 'Diamond Jenness' was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or 'Rat.'

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer. On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  20. 'Diamond Jenness': A Tough Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic of the target area called 'Diamond Jenness' was taken after NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool for a second time.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  1. Single particle maximum likelihood reconstruction from superresolution microscopy images

    PubMed Central

    Verdier, Timothée; Gunzenhauser, Julia; Manley, Suliana; Castelnovo, Martin

    2017-01-01

    Point localization superresolution microscopy enables fluorescently tagged molecules to be imaged beyond the optical diffraction limit, reaching single molecule localization precisions down to a few nanometers. For small objects whose sizes are few times this precision, localization uncertainty prevents the straightforward extraction of a structural model from the reconstructed images. We demonstrate in the present work that this limitation can be overcome at the single particle level, requiring no particle averaging, by using a maximum likelihood reconstruction (MLR) method perfectly suited to the stochastic nature of such superresolution imaging. We validate this method by extracting structural information from both simulated and experimental PALM data of immature virus-like particles of the Human Immunodeficiency Virus (HIV-1). MLR allows us to measure the radii of individual viruses with precision of a few nanometers and confirms the incomplete closure of the viral protein lattice. The quantitative results of our analysis are consistent with previous cryoelectron microscopy characterizations. Our study establishes the framework for a method that can be broadly applied to PALM data to determine the structural parameters for an existing structural model, and is particularly well suited to heterogeneous features due to its single particle implementation. PMID:28253349

  2. Uptake of silver nanoparticles by monocytic THP-1 cells depends on particle size and presence of serum proteins

    NASA Astrophysics Data System (ADS)

    Kettler, Katja; Giannakou, Christina; de Jong, Wim H.; Hendriks, A. Jan; Krystek, Petra

    2016-09-01

    Human health risks by silver nanoparticle (AgNP) exposure are likely to increase due to the increasing number of NP-containing products and demonstrated adverse effects in various cell lines. Unfortunately, results from (toxicity) studies are often based on exposure dose and are often measured only at a fixed time point. NP uptake kinetics and the time-dependent internal cellular concentration are often not considered. Macrophages are the first line of defense against invading foreign agents including NPs. How macrophages deal with the particles is essential for potential toxicity of the NPs. However, there is a considerable lack of uptake studies of particles in the nanometer range and macrophage-like cells. Therefore, uptake rates were determined over 24 h for three different AgNPs sizes (20, 50 and 75 nm) in medium with and without fetal calf serum. Non-toxic concentrations of 10 ng Ag/mL for monocytic THP-1 cells, representing realistic exposure concentration for short-term exposures, were chosen. The uptake of Ag was higher in medium without fetal calf serum and showed increasing uptake for decreasing NP sizes, both on NP mass and on number basis. Internal cellular concentrations reached roughly 32/10 %, 25/18 % and 21/15 % of the nominal concentration in the absence of fetal calf serum/with fetal calf serum for 20-, 50- and 75-nm NPs, respectively. Our research shows that uptake kinetics in macrophages differ for various NP sizes. To increase the understanding of the mechanism of NP toxicity in cells, the process of uptake (timing) should be considered.

  3. Computer measurement of particle sizes in electron microscope images

    NASA Technical Reports Server (NTRS)

    Hall, E. L.; Thompson, W. B.; Varsi, G.; Gauldin, R.

    1976-01-01

    Computer image processing techniques have been applied to particle counting and sizing in electron microscope images. Distributions of particle sizes were computed for several images and compared to manually computed distributions. The results of these experiments indicate that automatic particle counting within a reasonable error and computer processing time is feasible. The significance of the results is that the tedious task of manually counting a large number of particles can be eliminated while still providing the scientist with accurate results.

  4. 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

  5. [Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

    PubMed

    Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

    2014-09-01

    Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

  6. Sizes of particles formed during municipal wastewater treatment.

    PubMed

    Lech, Smoczynski; Marta, Kosobucka; Michal, Smoczynski; Harsha, Ratnaweera; Krystyna, Pieczulis-Smoczynska

    2017-02-01

    Volumetric diameters Dv and specific surface area SpS of sludge particles formed during chemical coagulation and electrocoagulation of sewage were determined. The obtained aggregate-flocs differed substantially in both Dv and SpS values. The differences in Dv and SpS values of the analyzed particles were interpreted based on theoretical models for expanding aggregates. The most uniform particles were formed under exposure to: (a) optimal and maximal doses of PIX, (b) optimal doses of PAX, (c) maximal doses of the Al electro-coagulant. The lowest PIX dose produced the least uniform particles. Sludge aggregates-particles produced under exposure to minimal doses of PIX and the Al electro-coagulant were characterized by the lowest SpS values. Sludge particles coagulated by PAX and the particles formed at higher doses of PIX and the Al electro-coagulant had higher SpS values. The particles formed at all doses of the applied coagulants and electro-coagulants were generally classified into two size ranges: the main range and the secondary range. Most particles belonged to the main size range. An increase in the percentage of colloidal hydroxide particles in sewage sludge increased SpS.

  7. Electrically conductive polycrystalline diamond and particulate metal based electrodes

    DOEpatents

    Swain, Greg M.; Wang, Jian

    2005-04-26

    An electrically conducting and dimensionally stable diamond (12, 14) and metal particle (13) electrode produced by electrodepositing the metal on the diamond is described. The electrode is particularly useful in harsh chemical environments and at high current densities and potentials. The electrode is particularly useful for generating hydrogen, and for reducing oxygen and oxidizing methanol in reactions which are of importance in fuel cells.

  8. 3D nanometer images of biological fibers by directed motion of gold nanoparticles.

    PubMed

    Estrada, Laura C; Gratton, Enrico

    2011-11-09

    Using near-infrared femtosecond pulses, we move single gold nanoparticles (AuNPs) along biological fibers, such as collagen and actin filaments. While the AuNP is sliding on the fiber, its trajectory is measured in three dimensions (3D) with nanometer resolution providing a high-resolution image of the fiber. Here, we systematically moved a single AuNP along nanometer-size collagen fibers and actin filament inside chinese hamster ovary K1 living cells, mapping their 3D topography with high fidelity.

  9. Electron emission from diamond films seeded using kitchen-wrap polyethylene

    NASA Astrophysics Data System (ADS)

    Varshney, D.; Makarov, V. I.; Saxena, P.; Guinel, M. J. F.; Kumar, A.; Scott, J. F.; Weiner, B. R.; Morell, G.

    2011-03-01

    Diamond has many potential electronic applications, but the diamond seeding methods are generally harsh on the substrates rendering them unsuitable for integration in electronics. We report a non-abrasive, scalable and economic process of diamond film seeding using kitchen-wrap polyethylene employing hot filament chemical vapour reaction of H2S/CH4/H2 gas mixtures on Cu substrates. The fabricated diamond films were characterized with scanning electron microscopy, transmission electron microscopy and Raman spectroscopy, which confirm that the deposited film consists of a microcrystalline diamond of size in the range 0.5-1.0 µm. The synthesized diamond films exhibit a turn-on field of about 8.5 V µm-1 and long-term stability. Diamond film synthesis using polyethylene will enable the integration of diamond heat sinks into high-power and high-temperature electronic devices.

  10. Evolution of Particle Size Distributions in Fragmentation Over Time

    NASA Astrophysics Data System (ADS)

    Charalambous, C. A.; Pike, W. T.

    2013-12-01

    We present a new model of fragmentation based on a probabilistic calculation of the repeated fracture of a particle population. The resulting continuous solution, which is in closed form, gives the evolution of fragmentation products from an initial block, through a scale-invariant power-law relationship to a final comminuted powder. Models for the fragmentation of particles have been developed separately in mainly two different disciplines: the continuous integro-differential equations of batch mineral grinding (Reid, 1965) and the fractal analysis of geophysics (Turcotte, 1986) based on a discrete model with a single probability of fracture. The first gives a time-dependent development of the particle-size distribution, but has resisted a closed-form solution, while the latter leads to the scale-invariant power laws, but with no time dependence. Bird (2009) recently introduced a bridge between these two approaches with a step-wise iterative calculation of the fragmentation products. The development of the particle-size distribution occurs with discrete steps: during each fragmentation event, the particles will repeatedly fracture probabilistically, cascading down the length scales to a final size distribution reached after all particles have failed to further fragment. We have identified this process as the equivalent to a sequence of trials for each particle with a fixed probability of fragmentation. Although the resulting distribution is discrete, it can be reformulated as a continuous distribution in maturity over time and particle size. In our model, Turcotte's power-law distribution emerges at a unique maturation index that defines a regime boundary. Up to this index, the fragmentation is in an erosional regime with the initial particle size setting the scaling. Fragmentation beyond this index is in a regime of comminution with rebreakage of the particles down to the size limit of fracture. The maturation index can increment continuously, for example under

  11. Diamonds from Orapa Mine show a clear subduction signature in SIMS stable isotope data

    NASA Astrophysics Data System (ADS)

    Chinn, Ingrid L.; Perritt, Samantha H.; Stiefenhofer, Johann; Stern, Richard A.

    2018-05-01

    Spatially resolved analyses reveal considerable isotopic heterogeneity within and among diamonds ranging in size from 0.15 to 4.75 mm from the Orapa Mine, Botswana. The isotopic data are interpreted in conjunction with nitrogen aggregation state data and growth zone relationships from cathodoluminescence images. The integrated information confirms that a distinct diamond growth event (with low IaAB nitrogen aggregation states, moderately high nitrogen contents and δ13C and δ15N values compatible with average mantle values) is younger than the dominant population(s) of Type IaAB diamonds and cores of composite diamonds with more negative and positive δ13C and δ15N values, respectively. A significant proportion of the older diamond generation has high nitrogen contents, well outside the limit sector relationship, and these diamonds are likely to reflect derivation from subducted organic matter. Diamonds with low δ13C values combined with high nitrogen contents and positive δ15N values have not been previously widely recognised, even in studies of diamonds from Orapa. This may have been caused by prior analytical bias towards inclusion-bearing diamonds that are not necessarily representative of the entire range of diamond populations, and because of average measurements from heterogeneous diamonds measured by bulk combustion methods. Two distinct low nitrogen/Type II microdiamond populations were recognised that do not appear to continue into the macrodiamond sizes in the samples studied. Other populations, e.g. those containing residual singly-substituted nitrogen defects, range in size from small microdiamonds to large macrodiamonds. The total diamond content of the Orapa kimberlite thus reflects a complex assortment of multiple diamond populations.

  12. Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

    NASA Astrophysics Data System (ADS)

    Ozen, Murat; Guler, Murat

    2014-02-01

    Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

  13. Electrochemistry at Nanometer-Scaled Electrodes

    ERIC Educational Resources Information Center

    Watkins, John J.; Bo Zhang; White, Henry S.

    2005-01-01

    Electrochemical studies using nanometer-scaled electrodes are leading to better insights into electrochemical kinetics, interfacial structure, and chemical analysis. Various methods of preparing electrodes of nanometer dimensions are discussed and a few examples of their behavior and applications in relatively simple electrochemical experiments…

  14. Effect of slurry composition on the chemical mechanical polishing of thin diamond films

    PubMed Central

    Werrell, Jessica M.; Mandal, Soumen; Thomas, Evan L. H.; Brousseau, Emmanuel B.; Lewis, Ryan; Borri, Paola; Davies, Philip R.; Williams, Oliver A.

    2017-01-01

    Nanocrystalline diamond (NCD) thin films grown by chemical vapour deposition have an intrinsic surface roughness, which hinders the development and performance of the films’ various applications. Traditional methods of diamond polishing are not effective on NCD thin films. Films either shatter due to the combination of wafer bow and high mechanical pressures or produce uneven surfaces, which has led to the adaptation of the chemical mechanical polishing (CMP) technique for NCD films. This process is poorly understood and in need of optimisation. To compare the effect of slurry composition and pH upon polishing rates, a series of NCD thin films have been polished for three hours using a Logitech Ltd. Tribo CMP System in conjunction with a polyester/polyurethane polishing cloth and six different slurries. The reduction in surface roughness was measured hourly using an atomic force microscope. The final surface chemistry was examined using X-ray photoelectron spectroscopy and a scanning electron microscope. It was found that of all the various properties of the slurries, including pH and composition, the particle size was the determining factor for the polishing rate. The smaller particles polishing at a greater rate than the larger ones. PMID:29057022

  15. Effect of slurry composition on the chemical mechanical polishing of thin diamond films

    NASA Astrophysics Data System (ADS)

    Werrell, Jessica M.; Mandal, Soumen; Thomas, Evan L. H.; Brousseau, Emmanuel B.; Lewis, Ryan; Borri, Paola; Davies, Philip R.; Williams, Oliver A.

    2017-12-01

    Nanocrystalline diamond (NCD) thin films grown by chemical vapour deposition have an intrinsic surface roughness, which hinders the development and performance of the films' various applications. Traditional methods of diamond polishing are not effective on NCD thin films. Films either shatter due to the combination of wafer bow and high mechanical pressures or produce uneven surfaces, which has led to the adaptation of the chemical mechanical polishing (CMP) technique for NCD films. This process is poorly understood and in need of optimisation. To compare the effect of slurry composition and pH upon polishing rates, a series of NCD thin films have been polished for three hours using a Logitech Ltd. Tribo CMP System in conjunction with a polyester/polyurethane polishing cloth and six different slurries. The reduction in surface roughness was measured hourly using an atomic force microscope. The final surface chemistry was examined using X-ray photoelectron spectroscopy and a scanning electron microscope. It was found that of all the various properties of the slurries, including pH and composition, the particle size was the determining factor for the polishing rate. The smaller particles polishing at a greater rate than the larger ones.

  16. Effects of particle size distribution in thick film conductors

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1983-01-01

    Studies of particle size distribution in thick film conductors are discussed. The distribution of particle sizes does have an effect on fired film density but the effect is not always positive. A proper distribution of sizes is necessary, and while the theoretical models can serve as guides to selecting this proper distribution, improved densities can be achieved by empirical variations from the predictions of the models.

  17. Submicrometer Particle Sizing by Multiangle Light Scattering following Fractionation

    PubMed

    Wyatt

    1998-01-01

    The acid test for any particle sizing technique is its ability to determine the differential number fraction size distribution of a simple, well-defined sample. The very best characterized polystyrene latex sphere standards have been measured extensively using transmission electron microscope (TEM) images of a large subpopulation of such samples or by means of the electrostatic classification method as refined at the National Institute of Standards and Technology. The great success, in the past decade, of on-line multiangle light scattering (MALS) detection combined with size exclusion chromatography for the measurement of polymer mass and size distributions suggested, in the early 1990s, that a similar attack for particle characterization might prove useful as well. At that time, fractionation of particles was achievable by capillary hydrodynamic chromatography (CHDF) and field flow fractionation (FFF) methods. The latter has proven most useful when combined with MALS to provide accurate differential number fraction size distributions for a broad range of particle classes. The MALS/FFF combination provides unique advantages and precision relative to FFF, photon correlation spectroscopy, and CHDF techniques used alone. For many classes of particles, resolution of the MALS/FFF combination far exceeds that of TEM measurements. Copyright 1998 Academic Press. Copyright 1998Academic Press

  18. Photographic techniques for characterizing streambed particle sizes

    USGS Publications Warehouse

    Whitman, Matthew S.; Moran, Edward H.; Ourso, Robert T.

    2003-01-01

    We developed photographic techniques to characterize coarse (>2-mm) and fine (≤2-mm) streambed particle sizes in 12 streams in Anchorage, Alaska. Results were compared with current sampling techniques to assess which provided greater sampling efficiency and accuracy. The streams sampled were wadeable and contained gravel—cobble streambeds. Gradients ranged from about 5% at the upstream sites to about 0.25% at the downstream sites. Mean particle sizes and size-frequency distributions resulting from digitized photographs differed significantly from those resulting from Wolman pebble counts for five sites in the analysis. Wolman counts were biased toward selecting larger particles. Photographic analysis also yielded a greater number of measured particles (mean = 989) than did the Wolman counts (mean = 328). Stream embeddedness ratings assigned from field and photographic observations were significantly different at 5 of the 12 sites, although both types of ratings showed a positive relationship with digitized surface fines. Visual estimates of embeddedness and digitized surface fines may both be useful indicators of benthic conditions, but digitizing surface fines produces quantitative rather than qualitative data. Benefits of the photographic techniques include reduced field time, minimal streambed disturbance, convenience of postfield processing, easy sample archiving, and improved accuracy and replication potential.

  19. Zooplankton Grazing Effects on Particle Size Spectra under Different Seasonal Conditions

    NASA Astrophysics Data System (ADS)

    Stamieszkin, K.; Poulton, N.; Pershing, A. J.

    2016-02-01

    Oceanic particle size spectra can be used to explain and predict variability in carbon export efficiency, since larger particles are more likely to sink to depth than small particles. The distribution of biogenic particle size in the surface ocean is the result of many variables and processes, including nutrient availability, primary productivity, aggregation, remineralization, and grazing. We conducted a series of grazing experiments to test the hypothesis that mesozooplankton shift particle size spectra toward larger particles, via grazing and egestion of relatively large fecal pellets. These experiments were carried out over several months, and used natural communities of mesozooplankton and their microbial prey, collected offshore of the Damariscotta River in the Gulf of Maine. We analyzed the samples using Fluid Imaging Technologies' FlowCam®, a particle imaging system. With this equipment, we processed live samples, decreasing the likelihood of losing or damaging fragile particles, and thereby lessening sources of error in commonly used preservation and enumeration protocols. Our results show how the plankton size spectrum changes as the Gulf of Maine progresses through a seasonal cycle. We explore the relationship of grazing community size structure to its effect on the overall biogenic particle size spectrum. At some times of year, mesozooplankton grazing does not alter the particle size spectrum, while at others it significantly does, affecting the potential for biogenic flux. We also examine prey selectivity, and find that chain diatoms are the only prey group preferentially consumed. Otherwise, we find that complete mesozooplankton communities are "evolved" to fit their prey such that most prey groups are grazed evenly. We discuss a metabolic numerical model which could be used to universalize the relationships between whole gazer and whole microbial communities, with respect to effects on particle size spectra.

  20. Measuring droplet size distributions from overlapping interferometric particle images.

    PubMed

    Bocanegra Evans, Humberto; Dam, Nico; van der Voort, Dennis; Bertens, Guus; van de Water, Willem

    2015-02-01

    Interferometric particle imaging provides a simple way to measure the probability density function (PDF) of droplet sizes from out-focus images. The optical setup is straightforward, but the interpretation of the data is a problem when particle images overlap. We propose a new way to analyze the images. The emphasis is not on a precise identification of droplets, but on obtaining a good estimate of the PDF of droplet sizes in the case of overlapping particle images. The algorithm is tested using synthetic and experimental data. We next use these methods to measure the PDF of droplet sizes produced by spinning disk aerosol generators. The mean primary droplet diameter agrees with predictions from the literature, but we find a broad distribution of satellite droplet sizes.

  1. Size distributions of manure particles released under simulated rainfall.

    PubMed

    Pachepsky, Yakov A; Guber, Andrey K; Shelton, Daniel R; McCarty, Gregory W

    2009-03-01

    Manure and animal waste deposited on cropland and grazing lands serve as a source of microorganisms, some of which may be pathogenic. These microorganisms are released along with particles of dissolved manure during rainfall events. Relatively little if anything is known about the amounts and sizes of manure particles released during rainfall, that subsequently may serve as carriers, abode, and nutritional source for microorganisms. The objective of this work was to obtain and present the first experimental data on sizes of bovine manure particles released to runoff during simulated rainfall and leached through soil during subsequent infiltration. Experiments were conducted using 200 cm long boxes containing turfgrass soil sod; the boxes were designed so that rates of manure dissolution and subsequent infiltration and runoff could be monitored independently. Dairy manure was applied on the upper portion of boxes. Simulated rainfall (ca. 32.4 mm h(-1)) was applied for 90 min on boxes with stands of either live or dead grass. Electrical conductivity, turbidity, and particle size distributions obtained from laser diffractometry were determined in manure runoff and soil leachate samples. Turbidity of leachates and manure runoff samples decreased exponentially. Turbidity of manure runoff samples was on average 20% less than turbidity of soil leachate samples. Turbidity of leachate samples from boxes with dead grass was on average 30% less than from boxes with live grass. Particle size distributions in manure runoff and leachate suspensions remained remarkably stable after 15 min of runoff initiation, although the turbidity continued to decrease. Particles had the median diameter of 3.8 microm, and 90% of particles were between 0.6 and 17.8 microm. The particle size distributions were not affected by the grass status. Because manure particles are known to affect transport and retention of microbial pathogens in soil, more information needs to be collected about the

  2. Ion-Implanted Diamond Films and Their Tribological Properties

    NASA Technical Reports Server (NTRS)

    Wu, Richard L. C.; Miyoshi, Kazuhisa; Korenyi-Both, Andras L.; Garscadden, Alan; Barnes, Paul N.

    1993-01-01

    This paper reports the physical characterization and tribological evaluation of ion-implanted diamond films. Diamond films were produced by microwave plasma, chemical vapor deposition technique. Diamond films with various grain sizes (0.3 and 3 microns) and roughness (9.1 and 92.1 nm r.m.s. respectively) were implanted with C(+) (m/e = 12) at an ion energy of 160 eV and a fluence of 6.72 x 10(exp 17) ions/sq cm. Unidirectional sliding friction experiments were conducted in ultrahigh vacuum (6.6 x 10(exp -7)Pa), dry nitrogen and humid air (40% RH) environments. The effects of C(+) ion bombardment on fine and coarse-grained diamond films are as follows: the surface morphology of the diamond films did not change; the surface roughness increased (16.3 and 135.3 nm r.m.s.); the diamond structures were damaged and formed a thin layer of amorphous non-diamond carbon; the friction coefficients dramatically decreased in the ultrahigh vacuum (0.1 and 0.4); the friction coefficients decreased slightly in the dry nitrogen and humid air environments.

  3. Global Particle Size Distributions: Measurements during the Atmospheric Tomography (ATom) Project

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Williamson, C.; Kupc, A.; Froyd, K. D.; Richardson, M.; Weinzierl, B.; Dollner, M.; Schuh, H.; Erdesz, F.

    2016-12-01

    The Atmospheric Tomography (ATom) project is a three-year NASA-sponsored program to map the spatial and temporal distribution of greenhouse gases, reactive species, and aerosol particles from the Arctic to the Antarctic. In situ measurements are being made on the NASA DC-8 research aircraft, which will make four global circumnavigations of the Earth over the mid-Pacific and mid-Atlantic Oceans while continuously profiling between 0.2 and 13 km altitude. In situ microphysical measurements will provide an unique and unprecedented dataset of aerosol particle size distributions between 0.004 and 50 µm diameter. This unbiased, representative dataset allows investigation of new particle formation in the remote troposphere, placing strong observational constraints on the chemical and physical mechanisms that govern particle formation and growth to cloud-active sizes. Particles from 0.004 to 0.055 µm are measured with 10 condensation particle counters. Particles with diameters from 0.06 to 1.0 µm are measured with one-second resolution using two ultra-high sensitivity aerosol size spectrometers (UHSASes). A laser aerosol spectrometer (LAS) measures particle size distributions between 0.12 and 10 µm in diameter. Finally, a cloud, aerosol and precipitation spectrometer (CAPS) underwing optical spectrometer probe sizes ambient particles with diameters from 0.5 to 50 µm and images and sizes precipitation-sized particles. Additional particle instruments on the payload include a high-resolution time-of-flight aerosol mass spectrometer and a single particle laser-ablation aerosol mass spectrometer. The instruments are calibrated in the laboratory and on the aircraft. Calibrations are checked in flight by introducing four sizes of polystyrene latex (PSL) microspheres into the sampling inlet. The CAPS probe is calibrated using PSL and glass microspheres that are aspirated into the sample volume. Comparisons between the instruments and checks with the calibration aerosol

  4. Particle size distribution: A key factor in estimating powder dustiness.

    PubMed

    López Lilao, Ana; Sanfélix Forner, Vicenta; Mallol Gasch, Gustavo; Monfort Gimeno, Eliseo

    2017-12-01

    A wide variety of raw materials, involving more than 20 samples of quartzes, feldspars, nephelines, carbonates, dolomites, sands, zircons, and alumina, were selected and characterised. Dustiness, i.e., a materials' tendency to generate dust on handling, was determined using the continuous drop method. These raw materials were selected to encompass a wide range of particle sizes (1.6-294 µm) and true densities (2650-4680 kg/m 3 ). The dustiness of the raw materials, i.e., their tendency to generate dust on handling, was determined using the continuous drop method. The influence of some key material parameters (particle size distribution, flowability, and specific surface area) on dustiness was assessed. In this regard, dustiness was found to be significantly affected by particle size distribution. Data analysis enabled development of a model for predicting the dustiness of the studied materials, assuming that dustiness depended on the particle fraction susceptible to emission and on the bulk material's susceptibility to release these particles. On the one hand, the developed model allows the dustiness mechanisms to be better understood. In this regard, it may be noted that relative emission increased with mean particle size. However, this did not necessarily imply that dustiness did, because dustiness also depended on the fraction of particles susceptible to be emitted. On the other hand, the developed model enables dustiness to be estimated using just the particle size distribution data. The quality of the fits was quite good and the fact that only particle size distribution data are needed facilitates industrial application, since these data are usually known by raw materials managers, thus making additional tests unnecessary. This model may therefore be deemed a key tool in drawing up efficient preventive and/or corrective measures to reduce dust emissions during bulk powder processing, both inside and outside industrial facilities. It is recommended, however

  5. A novel electroless method to prepare a platinum electrocatalyst on diamond for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Lyu, Xiao; Hu, Jingping; Foord, John S.; Wang, Qiang

    2013-11-01

    A novel electroless deposition method was demonstrated to prepare a platinum electrocatalyst on boron doped diamond (BDD) substrates without the need for pre-activation. This green method addresses the uniformity and particle size issues associated with electrodeposition and circumvents the pre-activation procedure which is necessary for conventional electroless deposition. The inert BDD substrate formed a galvanic couple with an iron wire, to overcome the activation barrier associated with conventional electroless deposition on diamond, leading to the formation of Pt nanoparticles on the electrode surface in a galvanic process coupled to a chemical process. When sodium hypophosphite was employed as the reducing agent to drive the electroless reaction Pt deposits which were contaminated with iron and phosphorus resulted. In contrast, the reducing agent ascorbic acid gave rise to high purity Pt nanoparticles. Optimal deposition conditions with respect to bath temperature, pH value and stabilizing additives are identified. Using this approach, high purity and uniformly distributed platinum nanoparticles are obtained on the diamond electrode surface, which demonstrate a high electrochemical activity towards methanol oxidation.

  6. Size-Dependent Particle Dynamics in Entangled Polymer Nanocomposites.

    PubMed

    Mangal, Rahul; Srivastava, Samanvaya; Narayanan, Suresh; Archer, Lynden A

    2016-01-19

    Polymer-grafted nanoparticles with diameter d homogeneously dispersed in entangled polymer melts with varying random coil radius R0, but fixed entanglement mesh size a(e), are used to study particle motions in entangled polymers. We focus on materials in the transition region between the continuum regime (d > R0), where the classical Stokes-Einstein (S-E) equation is known to describe polymer drag on particles, and the noncontinuum regime (d < a(e)), in which several recent studies report faster diffusion of particles than expected from continuum S-E analysis, based on the bulk polymer viscosity. Specifically, we consider dynamics of particles with sizes d ≥ a(e) in entangled polymers with varying molecular weight M(w) in order to investigate how the transition from noncontinuum to continuum dynamics occur. We take advantage of favorable enthalpic interactions between SiO2 nanoparticles tethered with PEO molecules and entangled PMMA host polymers to create model nanoparticle-polymer composites, in which spherical nanoparticles are uniformly dispersed in entangled polymers. Investigation of the particle dynamics via X-ray photon correlation spectroscopy measurements reveals a transition from fast to slow particle motion as the PMMA molecular weight is increased beyond the entanglement threshold, with a much weaker M(w) dependence for M(w) > M(e) than expected from S-E analysis based on bulk viscosity of entangled PMMA melts. We rationalize these observations using a simple force balance analysis around particles and find that nanoparticle motion in entangled melts can be described using a variant of the S-E analysis in which motion of particles is assumed to only disturb subchain entangled host segments with sizes comparable to the particle diameter.

  7. Size-Dependent Particle Dynamics in Entangled Polymer Nanocomposites

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

    Mangal, Rahul; Srivastava, Samanvaya; Narayanan, Suresh

    Polymer-grafted nanoparticles with diameter d homogeneously dispersed in entangled polymer melts with varying random coil radius R0, but fixed entanglement mesh size ae, are used to study particle motions in entangled polymers. We focus on materials in the transition region between the continuum regime (d > R0), where the classical Stokes-Einstein (S-E) equation is known to describe polymer drag on particles, and the non-continuum regime (d < ae), in which several recent studies report faster diffusion of particles than expected from continuum S-E analysis, based on the bulk polymer viscosity. Specifically, we consider dynamics of particles with sizes d ≥more » ae in entangled polymers with varying molecular weight Mw in order to investigate how the transition from non-continuum to continuum dynamics occur. We take advantage of favorable enthalpic interactions between SiO2 nanoparticles tethered with PEO molecules and entangled PMMA host polymers to create model nanoparticle-polymer composites, in which spherical nanoparticles are uniformly dispersed in entangled polymers. Investigation of the particle dynamics via X-ray photon correlation spectroscopy measurements reveal a transition from fast to slow particle motion as the PMMA molecular weight is increased beyond the entanglement threshold, with a much weaker Mw dependence for Mw>Me than expected from S-E analysis based on bulk viscosity of entangled PMMA melts. We rationalize these observations using a simple force balance analysis around particles and find that nanoparticle motion in entangled melts can be described using a variant of the S-E analysis in which motion of particles is assumed to only disturb sub-chain entangled host segments with sizes comparable to the particle diameter.« less

  8. Size-based sorting of micro-particles using microbubble streaming

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Jalikop, Shreyas; Hilgenfeldt, Sascha

    2009-11-01

    Oscillating microbubbles driven by ultrasound have shown great potential in microfluidic applications, such as transporting particles and promoting mixing [1-3]. The oscillations generate secondary steady streaming that can also trap particles. We use the streaming to develop a method of sorting particles of different sizes in an initially well-mixed solution. The solution is fed into a channel consisting of bubbles placed periodically along a side wall. When the bubbles are excited by an ultrasound piezo-electric transducer to produce steady streaming, the flow field is altered by the presence of the particles. This effect is dependent on particle size and results in size-based sorting of the particles. The effectiveness of the separation depends on the dimensions of the bubbles and particles as well as on the ultrasound frequency. Our experimental studies are aimed at a better understanding of the design and control of effective microfluidic separating devices. Ref: [1] P. Marmottant and S. Hilgenfeldt, Nature 423, 153 (2003). [2] P. Marmottant and S. Hilgenfeldt, Proc. Natl. Acad. Science USA, 101, 9523 (2004). [3] P. Marmottant, J.-P. Raven, H. Gardeniers, J. G. Bomer, and S. Hilgenfeldt, J. Fluid Mech., vol.568, 109 (2006).

  9. The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

    PubMed

    Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

    2013-12-01

    Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

  10. Measuring Charge Collection Efficiency in Diamond Vertex Detectors

    NASA Astrophysics Data System (ADS)

    Josey, Brian; Seidel, Sally; Hoeferkamp, Martin

    2011-10-01

    As currently used at the Large Hadron Collider, vertex detectors are composed primarily of silicon sensors that image particle tracks by detecting the creation of electron-hole pairs caused by the excitation of the silicon atoms. We are investigating replacing these silicon detectors with detectors made out of diamond. Diamond is advantageous due to its radiation hardness. We are measuring the charge collection efficiency of diamond as a function of fluence. We are building a characterization station. Diamond samples will be placed into the characterization station and exposed to a strontium-90 beta source, before and after I irradiate them with 800 MeV protons at LANL. The radiation from the Sr-90 source will create electron-hole pairs. These will be read out by applying an electric field across the sample. The system is triggered by a scintillator-photomultiplier tube assembly. The goal of this measurement is to record collected charge as a function of bias voltage. The diamond charge collection data will be compared to silicon and predictions about detector operation at the LHC will be made.

  11. Characterization of Raman Scattering in Solid Samples with Different Particle Sizes and Elucidation on the Trends of Particle Size-Dependent Intensity Variations in Relation to Changes in the Sizes of Laser Illumination and Detection Area.

    PubMed

    Duy, Pham K; Chun, Seulah; Chung, Hoeil

    2017-11-21

    We have systematically characterized Raman scatterings in solid samples with different particle sizes and investigated subsequent trends of particle size-induced intensity variations. For this purpose, both lactose powders and pellets composed of five different particle sizes were prepared. Uniquely in this study, three spectral acquisition schemes with different sizes of laser illuminations and detection windows were employed for the evaluation, since it was expected that the experimental configuration would be another factor potentially influencing the intensity of the lactose peak, along with the particle size itself. In both samples, the distribution of Raman photons became broader with the increase in particle size, as the mean free path of laser photons, the average photon travel distance between consecutive scattering locations, became longer under this situation. When the particle size was the same, the Raman photon distribution was narrower in the pellets since the individual particles were more densely packed in a given volume (the shorter mean free path). When the size of the detection window was small, the number of photons reaching the detector decreased as the photon distribution was larger. Meanwhile, a large-window detector was able to collect the widely distributed Raman photons more effectively; therefore, the trends of intensity change with the variation in particle size were dissimilar depending on the employed spectral acquisition schemes. Overall, the Monte Carlo simulation was effective at probing the photon distribution inside the samples and helped to support the experimental observations.

  12. Growth, characterization and device development in monocrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Davis, R. F.; Glass, J. T.; Nemanich, R. J.; Bozeman, S. P.; Sowers, A. T.

    1995-06-01

    Experimental and theoretical studies concerned with interface interactions of diamond with Si, Ni, and Ni3Si substrates have been conducted. Oriented diamond films deposited on (100) Si were characterized by polar Raman, polar x-ray diffraction (XRD), and cross-sectional high resolution transmission electron microscopy (HRTEM). These sutides showed that the diamond(100)/Si(100) interface adopted the 3:2-match arrangement rather than a 45 deg rotation. Extended Hueckel tight-binding (EHTB) electronic structure calculations for a model system revealed that the interface interaction favors the 3:2-match arrangement. Growth on polycrystalline Ni3Si resulted in oriented diamond particles; under the same growth conditions, graphite was formed on the nickel substrate. Our EHTB electronic structure calculations showed that the (111) and (100) surfaces of Ni3Si have a strong preference for diamond nucleation over graphite nucleation, but this was not the case for the (111) and (100) surfaces of Ni.

  13. Diamond anvil cells using boron-doped diamond electrodes covered with undoped diamond insulating layer

    NASA Astrophysics Data System (ADS)

    Matsumoto, Ryo; Yamashita, Aichi; Hara, Hiroshi; Irifune, Tetsuo; Adachi, Shintaro; Takeya, Hiroyuki; Takano, Yoshihiko

    2018-05-01

    Diamond anvil cells using boron-doped metallic diamond electrodes covered with undoped diamond insulating layers have been developed for electrical transport measurements under high pressure. These designed diamonds were grown on a bottom diamond anvil via a nanofabrication process combining microwave plasma-assisted chemical vapor deposition and electron beam lithography. The resistance measurements of a high-quality FeSe superconducting single crystal under high pressure were successfully demonstrated by just putting the sample and gasket on the bottom diamond anvil directly. The superconducting transition temperature of the FeSe single crystal was increased to up to 43 K by applying uniaxial-like pressure.

  14. Particle Size Reduction in Geophysical Granular Flows: The Role of Rock Fragmentation

    NASA Astrophysics Data System (ADS)

    Bianchi, G.; Sklar, L. S.

    2016-12-01

    Particle size reduction in geophysical granular flows is caused by abrasion and fragmentation, and can affect transport dynamics by altering the particle size distribution. While the Sternberg equation is commonly used to predict the mean abrasion rate in the fluvial environment, and can also be applied to geophysical granular flows, predicting the evolution of the particle size distribution requires a better understanding the controls on the rate of fragmentation and the size distribution of resulting particle fragments. To address this knowledge gap we are using single-particle free-fall experiments to test for the influence of particle size, impact velocity, and rock properties on fragmentation and abrasion rates. Rock types tested include granodiorite, basalt, and serpentinite. Initial particle masses and drop heights range from 20 to 1000 grams and 0.1 to 3.0 meters respectively. Preliminary results of free-fall experiments suggest that the probability of fragmentation varies as a power function of kinetic energy on impact. The resulting size distributions of rock fragments can be collapsed by normalizing by initial particle mass, and can be fit with a generalized Pareto distribution. We apply the free-fall results to understand the evolution of granodiorite particle-size distributions in granular flow experiments using rotating drums ranging in diameter from 0.2 to 4.0 meters. In the drums, we find that the rates of silt production by abrasion and gravel production by fragmentation scale with drum size. To compare these rates with free-fall results we estimate the particle impact frequency and velocity. We then use population balance equations to model the evolution of particle size distributions due to the combined effects of abrasion and fragmentation. Finally, we use the free-fall and drum experimental results to model particle size evolution in Inyo Creek, a steep, debris-flow dominated catchment, and compare model results to field measurements.

  15. Metrological assessment of a portable analyzer for monitoring the particle size distribution of ultrafine particles.

    PubMed

    Stabile, Luca; Cauda, Emanuele; Marini, Sara; Buonanno, Giorgio

    2014-08-01

    Adverse health effects caused by worker exposure to ultrafine particles have been detected in recent years. The scientific community focuses on the assessment of ultrafine aerosols in different microenvironments in order to determine the related worker exposure/dose levels. To this end, particle size distribution measurements have to be taken along with total particle number concentrations. The latter are obtainable through hand-held monitors. A portable particle size distribution analyzer (Nanoscan SMPS 3910, TSI Inc.) was recently commercialized, but so far no metrological assessment has been performed to characterize its performance with respect to well-established laboratory-based instruments such as the scanning mobility particle sizer (SMPS) spectrometer. The present paper compares the aerosol monitoring capability of the Nanoscan SMPS to the laboratory SMPS in order to evaluate whether the Nanoscan SMPS is suitable for field experiments designed to characterize particle exposure in different microenvironments. Tests were performed both in a Marple calm air chamber, where fresh diesel particulate matter and atomized dioctyl phthalate particles were monitored, and in microenvironments, where outdoor, urban, indoor aged, and indoor fresh aerosols were measured. Results show that the Nanoscan SMPS is able to properly measure the particle size distribution for each type of aerosol investigated, but it overestimates the total particle number concentration in the case of fresh aerosols. In particular, the test performed in the Marple chamber showed total concentrations up to twice those measured by the laboratory SMPS-likely because of the inability of the Nanoscan SMPS unipolar charger to properly charge aerosols made up of aggregated particles. Based on these findings, when field test exposure studies are conducted, the Nanoscan SMPS should be used in tandem with a condensation particle counter in order to verify and correct the particle size distribution data

  16. Counting particles emitted by stratospheric aircraft and measuring size of particles emitted by stratospheric aircraft

    NASA Technical Reports Server (NTRS)

    Wilson, James Charles

    1994-01-01

    The ER-2 condensation nuclei counter (CNC) has been modified to reduce the diffusive losses of particles within the instrument. These changes have been successful in improving the counting efficiency of small particles at low pressures. Two techniques for measuring the size distributions of particles with diameters less than 0.17 micrometers have been evaluated. Both of these methods, the differential mobility analyzer (DMA) and the diffusion battery, have fundamental problems that limit their usefulness for stratospheric applications. We cannot recommend either for this application. Newly developed, alternative methods for measuring small particles include inertial separation with a low-loss critical orifice and thin-plate impactor device. This technique is now used to collect particles in the multisample aerosol collector housed in the ER-2 CNC-2, and shows some promise for particle size measurements when coupled with a CNC as a counting device. The modified focused-cavity aerosol spectrometer (FCAS) can determine the size distribution of particles with ambient diameters as small as about 0.07 micrometers. Data from this instrument indicates the presence of a nuclei mode when CNC-2 indicates high concentrations of particles, but cannot resolve important parameters of the distribution.

  17. Effect of magnetic and electric coupling fields on micro- and nano- structure of carbon films in the CVD diamond process and their electron field emission property

    NASA Astrophysics Data System (ADS)

    Wang, Yijia; Li, Jiaxin; Hu, Naixiu; Jiang, Yunlu; Wei, Qiuping; Yu, Zhiming; Long, Hangyu; Zhu, Hekang; Xie, Youneng; Ma, Li; Lin, Cheng-Te; Su, Weitao

    2018-03-01

    In this paper, both electric field and magnetic field were used to assist the hot filament chemical vapor deposition (HFCVD) and we systematically investigated the effects of which on the (1) phase composition, (2) grain size, (3) thickness and (4) preferred orientation of diamond films through SEM, Raman and XRD. The application of magnetic field in electric field, so called ‘the magnetic and electric coupling fields’, enhanced the graphitization and refinement of diamond crystals, slowed down the decrease of film thickness along with the increase of bias current, and suppressed diamond (100) orientation. During the deposition process, the electric field provided additional energy to HFCVD system and generated large number of energetic particles which might annihilate at the substrate and lose kinetic energy, while the Lorentz force, provided by magnetic field, could constrict charged particles (including electrons) to do spiral movement, which prolonged their moving path and life, thus the system energy increased. With the graphitization of diamond films intensified, the preferred orientation of diamond films completely evolved from (110) to (100), until the orientation and diamond phase disappeared, which can be attributed to (I) the distribution and concentration ratio of carbon precursors (C2H2 and CH3) and (II) graphitization sequence of diamond crystal facets. Since the electron field emission property of carbon film is sensitive to the phase composition, thickness and preferred orientation, nano- carbon cones, prepared by the negative bias current of 20 mA and magnetic field strength of 80 Gauss, exhibited the lowest turn-on field of 6.1 V -1 μm-1.

  18. 'Diamond Jenness': Before the Grind

    NASA Image and Video Library

    2004-08-03

    This microscopic imager mosaic of the rock called "Diamond Jenness" was snapped on sol 177 before NASA's Mars Exploration Rover Opportunity ground into the surface with its rock abrasion tool, or "Rat." Opportunity has bored nearly a dozen holes into the inner walls of "Endurance Crater." On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer. On Sol 178, Opportunity's "robotic rodent" dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed. The image mosaic is about 6 centimeters (2.4 inches) across. http://photojournal.jpl.nasa.gov/catalog/PIA06748

  19. High-resolution, submicron particle size distribution analysis using gravitational-sweep sedimentation.

    PubMed Central

    Mächtle, W

    1999-01-01

    Sedimentation velocity is a powerful tool for the analysis of complex solutions of macromolecules. However, sample turbidity imposes an upper limit to the size of molecular complexes currently amenable to such analysis. Furthermore, the breadth of the particle size distribution, combined with possible variations in the density of different particles, makes it difficult to analyze extremely complex mixtures. These same problems are faced in the polymer industry, where dispersions of latices, pigments, lacquers, and emulsions must be characterized. There is a rich history of methods developed for the polymer industry finding use in the biochemical sciences. Two such methods are presented. These use analytical ultracentrifugation to determine the density and size distributions for submicron-sized particles. Both methods rely on Stokes' equations to estimate particle size and density, whereas turbidity, corrected using Mie's theory, provides the concentration measurement. The first method uses the sedimentation time in dispersion media of different densities to evaluate the particle density and size distribution. This method works provided the sample is chemically homogeneous. The second method splices together data gathered at different sample concentrations, thus permitting the high-resolution determination of the size distribution of particle diameters ranging from 10 to 3000 nm. By increasing the rotor speed exponentially from 0 to 40,000 rpm over a 1-h period, size distributions may be measured for extremely broadly distributed dispersions. Presented here is a short history of particle size distribution analysis using the ultracentrifuge, along with a description of the newest experimental methods. Several applications of the methods are provided that demonstrate the breadth of its utility, including extensions to samples containing nonspherical and chromophoric particles. PMID:9916040

  20. Size-resolved particle emission factors for individual ships

    NASA Astrophysics Data System (ADS)

    Jonsson, Åsa M.; Westerlund, Jonathan; Hallquist, Mattias

    2011-07-01

    In these experiments size-resolved emission factors for particle number (EFPN) and mass (EFPM) have been determined for 734 individual ship passages for real-world dilution. The method used is an extractive sampling method of the passing ship plumes where particle number/mass and CO2 were measured with high time resolution (1 Hz). The measurements were conducted on a small island located in the entrance to the port of Gothenburg (N57.6849, E11.838), the largest harbor in Scandinavia. This is an emission control area (ECA) and in close vicinity to populated areas. The average EFPN and EFPM were 2.55 ± 0.11 × 1016 (kg fuel)-1 and 2050 ± 110 mg (kg fuel)-1, respectively. The determined EF for ships with multiple passages showed a great reproducibility. Size-resolved EFPN were peaking at small particle sizes ˜35 nm. Smaller particle sizes and hence less mass were observed by a gas turbine equipped ship compared to diesel engine equipped ships. On average 36 to 46% of the emitted particles by number were non-volatile and 24% by mass (EFPN 1.16 ± 0.19 × 1016 [kg fuel]-1 and EFPM 488 ± 73 mg [kg fuel]-1, respectively). This study shows a great potential to gain large data-sets regarding ship emission determining parameters that can improve current dispersion modeling for health assessments on local and regional scales. The global contributions of total and non-volatile particle mass from shipping using this extensive data-set from an ECA were estimated to be at least 0.80 Tgy-1 and 0.19 Tgy-1.

  1. Size-selective separation of submicron particles in suspensions with ultrasonic atomization.

    PubMed

    Nii, Susumu; Oka, Naoyoshi

    2014-11-01

    Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Particle size reduction of propellants by cryocycling

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

    Whinnery, L.; Griffiths, S.; Lipkin, J.

    1995-05-01

    Repeated exposure of a propellant to liquid nitrogen causes thermal stress gradients within the material resulting in cracking and particle size reduction. This process is termed cryocycling. The authors conducted a feasibility study, combining experiments on both inert and live propellants with three modeling approaches. These models provided optimized cycle times, predicted ultimate particle size, and allowed crack behavior to be explored. Process safety evaluations conducted separately indicated that cryocycling does not increase the sensitivity of the propellants examined. The results of this study suggest that cryocycling is a promising technology for the demilitarization of tactical rocket motors.

  3. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, Ralph L.; Stewart, Delbert D.; Evans, Christopher J.

    1992-01-01

    Apparatus for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond.

  4. Alpha-Voltaic Sources Using Diamond as Conversion Medium

    NASA Technical Reports Server (NTRS)

    Patel, Jagadish U.; Fleurial, Jean-Pierre; Kolawa, Elizabeth

    2006-01-01

    A family of proposed miniature sources of power would exploit the direct conversion of the kinetic energy of a particles into electricity in diamond semiconductor diodes. These power sources would function over a wide range of temperatures encountered in terrestrial and outer-space environments. These sources are expected to have operational lifetimes of 10 to 20 years and energy conversion efficiencies >35 percent. A power source according to the proposal would include a pair of devices like that shown in the figure. Each device would contain Schottky and p/n diode devices made from high-band-gap, radiation-hard diamond substrates. The n and p layers in the diode portion would be doped sparsely (<1014 cm-3) in order to maximize the volume of the depletion region and thereby maximize efficiency. The diode layers would be supported by an undoped diamond substrate. The source of a particles would be a thin film of 244Cm (half-life 18 years) sandwiched between the two paired devices. The sandwich arrangement would force almost every a particle to go through the active volume of at least one of the devices. Typical a particle track lengths in the devices would range from 20 to 30 microns. The a particles would be made to stop only in the undoped substrates to prevent damage to the crystalline structures of the diode portions. The overall dimensions of a typical source are expected to be about 2 by 2 by 1 mm. Assuming an initial 244Cm mass of 20 mg, the estimated initial output of the source is 20 mW (a current of 20 mA at a potential of 1 V).

  5. Particles influence allergic responses in mice--role of gender and particle size.

    PubMed

    Alberg, Torunn; Hansen, Jitka Stilund; Lovik, Martinus; Nygaard, Unni Cecilie

    2014-01-01

    Epidemiological evidence suggesting that exposure to traffic air pollution may enhance sensitization to common allergens in children is increasing, and animal studies support biological plausibility and causality. The effect of air pollution on respiratory symptoms was suggested to be gender dependent. Previous studies showed that allergy-promoting activity of polystyrene particles (PSP) increased with decreasing particle size after footpad injection of mice. The primary aim of this study was to confirm the influence of particle size on the immunoglobulin E (IgE)-promoting capacity of particles in an airway allergy model. A second aim was to examine whether the allergy-promoting capacity of particles was influenced by gender. Female and male mice were intranasally exposed to the allergen ovalbumin (OVA) with or without ultrafine, fine, or coarse PSP modeling the core of ambient air particles. After intranasal booster immunizations with OVA, serum levels of OVA-specific IgE antibodies, and also markers of airway inflammation and cellular responses in the lung-draining mediastinal lymph nodes (MLN), were determined. PSP of all sizes promoted allergic responses, measured as increased serum concentrations of OVA-specific IgE antibodies. Further, PSP produced eosinophilic airway inflammation and elevated MLN cell numbers as well as numerically reducing the percentage of regulatory T cells. Ultrafine PSP produced stronger allergic responses to OVA than fine and coarse PSP. Although PSP enhanced sensitization in both female and male mice, significantly higher IgE levels and numbers of eosinophils were observed in females than males. However, the allergy-promoting effect of PSP was apparently independent of gender. Thus, our data support the notion that ambient air particle pollution may affect development of allergy in both female and male individuals.

  6. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes.

    PubMed

    Zhang, Bo; Edwards, Brian J

    2015-06-07

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated with the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.

  7. Absolute age Determinations on Diamond by Radioisotopic Methods: NOT the way to Accurately Identify Diamond Provenance

    NASA Astrophysics Data System (ADS)

    Shirey, S. B.

    2002-05-01

    Gem-quality diamond contains such low abundances of parent-daughter radionuclides that dating the diamond lattice directly by isotopic measurements has been and will be impossible. Absolute ages on diamonds typically are obtained through measurements of their syngenetic mineral inclusions: Rb-Sr in garnet; Sm-Nd in garnet and pyroxene; Re-Os and U-Th-Pb in sulfide; K-Ar in pyroxene; and U-Pb in zircon. The application of the first two isotope schemes in the list requires putting together many inclusions from many diamonds whereas the latter isotope schemes permit ages on single diamonds. The key limitations on the application of these decay pairs are the availability and size of the inclusions, the abundance levels of the radionuclides, and instrumental sensitivity. Practical complications of radioisotope dating of inclusions are fatal to the application of the technique for diamond provenance. In all mines, the ratio of gem-quality diamonds to stones with datable inclusions is very high. Thus there is no way to date the valuable, marketable stones that are part of the conflict diamond problem, just their rare, flawed cousins. Each analysis destroys the diamond host plus the inclusion and can only be carried out in research labs by highly trained scientists. Thus, these methods can not be automated or applied to the bulk of diamond production. The geological problems with age dating are equally fatal to its application to diamond provenance. From the geological perspective, for age determination to work as a tool for diamond provenance studies, diamond ages would have to be specific to particular kimberlites or kimberlite fields and different between fields. The southern African Kaapvaal-Zimbabwe Craton and Limpopo Mobile Belt is the only cratonic region where age determinations have been applied on a large enough scale to a number of kimberlites to illustrate the geological problems in age measurements for diamond provenance. However, this southern African example

  8. Enhancement of fluorescence intensity by silicon particles and its size effect.

    PubMed

    Saitow, Ken-ichi; Suemori, Hidemi; Tamamitsu, Hironori

    2014-02-04

    Fluorescence-intensity enhancement of dye molecules was investigated using silicon submicron particles as a function of the particle size. Silicon particles with a size of 500 nm gave an enhancement factor up to 180. Measurement of scattering spectra revealed that the localized electric field at the particle enhances the fluorescence intensity.

  9. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    DOEpatents

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    2015-11-17

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Also disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.

  10. Diamond tool machining of materials which react with diamond

    DOEpatents

    Lundin, R.L.; Stewart, D.D.; Evans, C.J.

    1992-04-14

    An apparatus is described for the diamond machining of materials which detrimentally react with diamond cutting tools in which the cutting tool and the workpiece are chilled to very low temperatures. This chilling halts or retards the chemical reaction between the workpiece and the diamond cutting tool so that wear rates of the diamond tool on previously detrimental materials are comparable with the diamond turning of materials which do not react with diamond. 1 figs.

  11. A review on preparation of silver nano-particles

    NASA Astrophysics Data System (ADS)

    Haider, Adawiya J.; Haider, Mohammad J.; Mehde, Mohammad S.

    2018-05-01

    The term "nano particle" (NP) refers to particle diameter in nanometers in size. Nanoparticles contain a small number of constituent atoms or molecules that differ from the properties inherent in their bulk counterparts, found in various forms such as spherical, triangular, cubic, pentagonal, rod-shaped, shells, elliptical and so on. In this chapter, it has been presented the theoretical concepts of the preparation of AgNPS as powders and collide nanoparticles, techniques of preparation with their characterization (morphology, sign charge and potential value, particle distribution ….etc.). Also, included unique properties of AgNPS that are different from those of their bulk materials like: High surface area to volume ratio effects Quantization of electronic and vibration properties.

  12. Laser diffraction particle sizing in STRESS

    NASA Astrophysics Data System (ADS)

    Agrawal, Y. C.; Pottsmith, H. C.

    1994-08-01

    An autonomous instrument system for measuring particle size spectra in the sea is described. The instrument records the small-angle scattering characteristics of the particulate ensemble present in water. The small-angle scattering distribution is inverted into size spectra. The discussion of the instrument in this paper is included with a review of the information content of the data. It is noted that the inverse problem is sensitive to the forward model for light scattering employed in the construction of the matrix. The instrument system is validated using monodisperse polystyrene and NIST standard distributions of glass spheres. Data from a long-term deployment on the California shelf during the field experiment Sediment Transport Events on Shelves and Slopes (STRESS) are included. The size distribution in STRESS, measured at a fixed height-above-bed 1.2 m, showed significant variability over time. In particular, the volume distribution sometimes changed from mono-modal to bi-modal during the experiment. The data on particle-size distribution are combined with friction velocity measurements in the current boundary layer to produce a size-dependent estimate of the suspended mass at 10 cm above bottom. It is argued that these concentrations represent the reference concentration at the bed for the smaller size classes. The suspended mass at all sizes shows a strong correlation with wave variance. Using the size distribution, corrections in the optical transmissometry calibration factor are estimated for the duration of the experiment. The change in calibration at 1.2 m above bed (mab) is shown to have a standard error of 30% over the duration of the experiment with a range of 1.8-0.8.

  13. Particle characteristics of different materials after ultra-short pulsed laser (USPL) irradiation

    NASA Astrophysics Data System (ADS)

    Meister, Joerg; Schelle, Florian; Kowalczyk, Philip; Frentzen, Matthias

    2012-01-01

    The exposition of nanoparticles caused by laser application in dental health care is an open discussion. Based on the fact that nanoparticles can penetrate through the mucosa, the knowledge about particle characteristics after irradiation with an USPL is of high importance. Therefore, the aim of this study was to investigate the particle characteristics, especially the size of the ablated debris after USPL irradiation. The irradiation was carried out with an USP Nd:YVO4 laser with a center wavelength of 1064 nm. Based on the pulse duration of 8 ps and a pulse repetition rate of 500 kHz the laser emits an average power of 9 W. The materials investigated were dental tissues and dental restorative materials (composite and amalgam), ceramic and different metals (gold and aluminium). The samples were irradiated with a power density in the order of 300 GW/cm2 at distances of 5, 10, 15, and 20 mm. The debris was collected on an object plate. SEM pictures were used for analysis of the ablation debris. Depending on the irradiated material, we observed different kinds of structures: vitreous, flocculent, and pellet-like. The mean particle sizes were 10 x 10 up to 30 x 30 μm2. In addition, a cluster of ablated matter (nanometer range) distributed over the whole irradiated area was found. With increasing distances the cluster structure reduced from multi-layer to mono-layer clusters. Particle sizes in the micrometer and nanometer range were found after irradiation with an USPL. The nanoparticles create a cluster structure which is influenced by increasing distances.

  14. Size-resolved ultrafine particle composition analysis 1. Atlanta

    NASA Astrophysics Data System (ADS)

    Rhoads, K. P.; Phares, D. J.; Wexler, A. S.; Johnston, M. V.

    2003-04-01

    During August 1999 as part of the Southern Oxidants Study Supersite Experiment, our group collected size-resolved measurements of the chemical composition of single ambient aerosol particles with a unique real-time laser desorption/ionization mass spectrometry technique. The rapid single-particle mass spectrometry instrument is capable of analyzing "ultrafine" particles with aerodynamic diameters ranging from 0.01 to 1.5 μm. Under the heaviest loading observed in Atlanta, particles were analyzed at a rate of roughly one per second in sizes ranging from 0.1 to 0.2 μm. Nearly 16,000 individual spectra were recorded over the course of the month during both daytime and nighttime sampling periods. Evaluation of the data indicates that the composition of the ultrafine (less than 100 nm) particles is dominated by carbon-containing compounds. Larger particles show varied compositions but typically appeared to have organic carbon characteristics mixed with an inorganic component (e.g., crustal materials, metals, etc.). During the experiment, 70 composition classes were identified. In this paper we report the average spectra and correlations with various meteorological parameters for all major compound classes and a number of minor ones. The major composition classes are identified from the primary peaks in their spectra as organic carbon (about 74% of the particles), potassium (8%), iron (3%), calcium (2%), nitrate (2%), elemental carbon (1.5%), and sodium (1%). Many of these compound classes appeared in repeatable size ranges and quadrants of the wind rose, indicating emission from specific sources.

  15. Structural and Electronic Properties of Isolated Nanodiamonds: A Theoretical Perspective

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

    Raty, J; Galli, G

    2004-09-09

    Nanometer sized diamond has been found in meteorites, proto-planetary nebulae and interstellar dusts, as well as in residues of detonation and in diamond films. Remarkably, the size distribution of diamond nanoparticles appears to be peaked around 2-5 nm, and to be largely independent of preparation conditions. Using ab-initio calculations, we have shown that in this size range nanodiamond has a fullerene-like surface and, unlike silicon and germanium, exhibit very weak quantum confinement effects. We called these carbon nanoparticles bucky-diamonds: their atomic structure, predicted by simulations, is consistent with many experimental findings. In addition, we carried out calculations of the stabilitymore » of nanodiamond which provided a unifying explanation of its size distribution in extra-terrestrial samples, and in ultra-crystalline diamond films. Here we present a summary of our theoretical results and we briefly outline work in progress on doping of nanodiamond with nitrogen.« less

  16. Analysis of the application of poly-nanocrystalline diamond tools for ultra precision machining of steel with ultrasonic assistance

    NASA Astrophysics Data System (ADS)

    Doetz, M.; Dambon, O.; Klocke, F.; Bulla, B.; Schottka, K.; Robertson, D. J.

    2017-10-01

    Ultra-precision diamond turning enables the manufacturing of parts with mirror-like surfaces and highest form accuracies out of non-ferrous, a few crystalline and plastic materials. Furthermore, an ultrasonic assistance has the ability to push these boundaries and enables the machining of materials like steel, which is not possible in a conventional way due to the excessive tool wear caused by the affinity of carbon to iron. Usually monocrystalline diamonds tools are applied due to their unsurpassed cutting edge properties. New cutting tool material developments have shown that it is possible to produce tools made of nano-polycrystalline diamonds with cutting edges equivalent to monocrystalline diamonds. In nano-polycrystalline diamonds ultra-fine grains of a few tens of nanometers are firmly and directly bonded together creating an unisotropic structure. The properties of this material are described to be isotropic, harder and tougher than those of the monocrystalline diamonds, which are unisotropic. This publication will present machining results from the newest investigations of the process potential of this new polycrystalline cutting material. In order to provide a baseline with which to characterize the cutting material cutting experiments on different conventional machinable materials like Cooper or Aluminum are performed. The results provide information on the roughness and the topography of the surface focusing on the comparison to the results while machining with monocrystalline diamond. Furthermore, the cutting material is tested in machining steel with ultrasonic assistance with a focus on tool life time and surface roughness. An outlook on the machinability of other materials will be given.

  17. Particle size-dependent radical generation from wildland fire smoke.

    PubMed

    Leonard, Stephen S; Castranova, Vince; Chen, Bean T; Schwegler-Berry, Diane; Hoover, Mark; Piacitelli, Chris; Gaughan, Denise M

    2007-07-01

    Firefighting, along with construction, mining and agriculture, ranks among the most dangerous occupations. In addition, the work environment of firefighters is unlike that of any other occupation, not only because of the obvious physical hazards but also due to the respiratory and systemic health hazards of smoke inhalation resulting from combustion. A significant amount of research has been devoted to studying municipal firefighters; however, these studies may not be useful in wildland firefighter exposures, because the two work environments are so different. Not only are wildland firefighters exposed to different combustion products, but their exposure profiles are different. The combustion products wildland firefighters are exposed to can vary greatly in characteristics due to the type and amount of material being burned, soil conditions, temperature and exposure time. Smoke inhalation is one of the greatest concerns for firefighter health and it has been shown that the smoke consists of a large number of particles. These smoke particles contain intermediates of hydrogen, carbon and oxygen free radicals, which may pose a potential health risk. Our investigation looked into the involvement of free radicals in smoke toxicity and the relationship between particle size and radical generation. Samples were collected in discrete aerodynamic particle sizes from a wildfire in Alaska, preserved and then shipped to our laboratory for analysis. Electron spin resonance was used to measure carbon-centered as well as hydroxyl radicals produced by a Fenton-like reaction with wildfire smoke. Further study of reactive oxygen species was conducted using analysis of cellular H(2)O(2) generation, lipid peroxidation of cellular membranes and DNA damage. Results demonstrate that coarse size-range particles contained more carbon radicals per unit mass than the ultrafine particles; however, the ultrafine particles generated more *OH radicals in the acellular Fenton-like reaction. The

  18. Particle Size Distributions in Atmospheric Clouds

    NASA Technical Reports Server (NTRS)

    Paoli, Roberto; Shariff, Karim

    2003-01-01

    In this note, we derive a transport equation for a spatially integrated distribution function of particles size that is suitable for sparse particle systems, such as in atmospheric clouds. This is done by integrating a Boltzmann equation for a (local) distribution function over an arbitrary but finite volume. A methodology for evolving the moments of the integrated distribution is presented. These moments can be either tracked for a finite number of discrete populations ('clusters') or treated as continuum variables.

  19. Complex biomembrane mimetics on the sub-nanometer scale

    DOE PAGES

    Heberle, Frederick A.; Pabst, Georg

    2017-07-17

    Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain forming lipid mixtures to asymmetric lipid bilayers. We review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. Particularly we focus on: (i) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function ofmore » a size transition from nanoscopic to macroscopic domains; (ii) membrane-mediated protein partitioning into lipid domains; (iii) the role of the aqueous medium in tuning interactions between membranes and domains; and (iv) leaflet specific structure in asymmetric bilayers and passive lipid flip-flop.« less

  20. Complex biomembrane mimetics on the sub-nanometer scale

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

    Heberle, Frederick A.; Pabst, Georg

    Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain forming lipid mixtures to asymmetric lipid bilayers. We review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. Particularly we focus on: (i) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function ofmore » a size transition from nanoscopic to macroscopic domains; (ii) membrane-mediated protein partitioning into lipid domains; (iii) the role of the aqueous medium in tuning interactions between membranes and domains; and (iv) leaflet specific structure in asymmetric bilayers and passive lipid flip-flop.« less

  1. Counting Particles Emitted by Stratospheric Aircraft and Measuring Size of Particles Emitted by Stratospheric Aircraft

    NASA Technical Reports Server (NTRS)

    Wilson, James Charles

    1994-01-01

    There were two principal objectives of the cooperative agreement between NASA and the University of Denver. The first goal was to modify the design of the ER-2 condensation nuclei counter (CNC) so that the effective lower detection limit would be improved at high altitudes. This improvement was sought because, in the instrument used prior to 1993, diffusion losses prevented the smallest detectable particles from reaching the detection volume of the instrument during operation at low pressure. Therefore, in spite of the sensor's ability to detect particles as small as 0.008 microns in diameter, many of these particles were lost in transport to the sensing region and were not counted. Most of the particles emitted by aircraft are smaller than 0.1 micron in diameter. At the start date of this work, May 1990, continuous sizing techniques available on the ER-2 were only capable of detecting particles larger than 0.17 micron. Thus, the second objective of this work was to evaluate candidate sizing techniques in an effort to gain additional information concerning the size of particles emitted by aircraft.

  2. Cytotoxicity evaluation of ceramic particles of different sizes and shapes.

    PubMed

    Yamamoto, Akiko; Honma, Rieko; Sumita, Masae; Hanawa, Takao

    2004-02-01

    When artificial hip or knee joints are implanted in the human body, they release metallic, ceramic, and polymeric debris into the surrounding tissues. The toxicity of the released particles is of two types: chemical, caused by the released soluble ions and monomers, and mechanical, a result of mechanical stimulation produced by the insoluble particles. In this study, the cytotoxicity of particles of TiO2, Al2O3, ZrO2, Si3N4, and SiC for murine fibroblasts and macrophages were examined to evaluate just their mechanical toxicity because these particles are not expected to release soluble metal ions. Different sizes and shapes of TiO2 particles were used to evaluate the effect of size and shape on particle cytotoxicity. The results suggest that the cytotoxicity of ceramic particles does not depend on their chemical species. Cytotoxicity levels were lower than those of corresponding metal ions, indicating that the mechanical toxicity of particles is lower than the chemical toxicity of released soluble ions and monomers. The differences in size did not affect the mechanical toxicity of these particles. The dendritic particles had a higher cytotoxicity level for macrophages than did spindle and spheric particles. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 244-256, 2004

  3. The influences of ambient particle composition and size on particle infiltration in Los Angeles, CA, residences.

    PubMed

    Sarnat, Stefanie Ebelt; Coull, Brent A; Ruiz, Pablo A; Koutrakis, Petros; Suh, Helen H

    2006-02-01

    Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH4NO3). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (FINF), for fine particles (PM2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO3-]) components, and particle sizes ranging between 0.02 and 10 microm. FINF was highest for BC (median = 0.84) and lowest for NO3- (median = 0.18). The low FINF for NO3- was likely because of volatilization of NO3- particles once indoors, in addition to depositional losses upon building entry. The FINF for PM2.5 (median = 0.48) fell between those for BC and NO3-, reflecting the contributions of both particle components to PM25. FINF varied with particle size, air-exchange rate, and outdoor NO3- concentrations. The FINF for particles between 0.7 and 2 microm in size was considerably lower during periods of high as compared with low outdoor NO3- concentrations, suggesting that outdoor NO3- particles were of this size. This study demonstrates that infiltration of PM2.5 varies by particle component and is lowest for volatile species, such as NH4NO3. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas

  4. Toxicogenomic analysis of the particle dose- and size-response relationship of silica particles-induced toxicity in mice

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoyan; Jin, Tingting; Jin, Yachao; Wu, Leihong; Hu, Bin; Tian, Yu; Fan, Xiaohui

    2013-01-01

    This study investigated the relationship between particle size and toxicity of silica particles (SP) with diameters of 30, 70, and 300 nm, which is essential to the safe design and application of SP. Data obtained from histopathological examinations suggested that SP of these sizes can all induce acute inflammation in the liver. In vivo imaging showed that intravenously administrated SP are mainly present in the liver, spleen and intestinal tract. Interestingly, in gene expression analysis, the cellular response pathways activated in the liver are predominantly conserved independently of particle dose when the same size SP are administered or are conserved independently of particle size, surface area and particle number when nano- or submicro-sized SP are administered at their toxic doses. Meanwhile, integrated analysis of transcriptomics, previous metabonomics and conventional toxicological results support the view that SP can result in inflammatory and oxidative stress, generate mitochondrial dysfunction, and eventually cause hepatocyte necrosis by neutrophil-mediated liver injury.

  5. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2013-01-01

    Estimated 2012 world production of natural and synthetic industrial diamond was about 4.45 billion carats. During 2012, natural industrial diamonds were produced in at least 20 countries, and synthetic industrial diamond was produced in at least 12 countries. About 99 percent of the combined natural and synthetic global output was produced in Belarus, China, Ireland, Japan, Russia, South Africa and the United States. During 2012, China was the world’s leading producer of synthetic industrial diamond followed by the United States and Russia. In 2012, the two U.S. synthetic producers, one in Pennsylvania and the other in Ohio, had an estimated output of 103 million carats, valued at about $70.6 million. This was an estimated 43.7 million carats of synthetic diamond bort, grit, and dust and powder with a value of $14.5 million combined with an estimated 59.7 million carats of synthetic diamond stone with a value of $56.1 million. Also in 2012, nine U.S. firms manufactured polycrystalline diamond (PCD) from synthetic diamond grit and powder. The United States government does not collect or maintain data for either domestic PCD producers or domestic chemical vapor deposition (CVD) diamond producers for quantity or value of annual production. Current trade and consumption quantity data are not available for PCD or for CVD diamond. For these reasons, PCD and CVD diamond are not included in the industrial diamond quantitative data reported here.

  6. Influence of particle size on physical and sensory attributes of mango pulp powder

    NASA Astrophysics Data System (ADS)

    Sharma, M.; Kadam, D. M.; Chadha, S.; Wilson, R. A.; Gupta, R. K.

    2013-09-01

    The present investigation was aimed to observe the effect of particle size on physical, sensory and thermal properties of foam-mat dried mango pulp powder. Mango pulp of Dussehri variety was foam-mat dried using 3% egg white at 65ºC. Dried foam-mats were pulverized and passed through a sieve shaker for obtaining three grades of powder with 50, 60, and 85 mesh size sieves. The particle size of these samples measured using laser diffraction particle size analyzer ranged from 191.26 to 296.19 μm. The data was analysed statistically using ANOVA of SAS. There was a linear increase in lightness (`L' value) with a decrease in particle size, however, `a' value decreased with a decrease in particle size, indicating the decrease in redness. An increase in bulk density and decrease in water solubility index and water absorption index % were observed with a decrease in particle size. Particle size had a significant effect on sensory parameters. Particle size in the range of 258.01 to 264.60μmwas found most acceptable with respect to sensory characteristics. This finding can be exploited for various commercial applicationswhere powder quality is dependent on the particle size and has foremost priority for end users.

  7. BRL Particle Sizing Interferometer

    DTIC Science & Technology

    1982-07-01

    satisfy the counting constraints required for entry into the ■ Histogran Counter. ACQUISITION TIME -~ The tiwe which elapsed during data acquistion ...weighted population (i.e., Measured population tines the weighting factor) of a bin in the particle size histogran acquistion . Does not include data...1000.0 40.0 3000 1 ZING FROM PSI OMHZ M MHZ MHZ V. VOLTS PED HZ ODE ON PAD ZCD=3.7 ADJUST OFF; IRIG HISTOGRAM E:ET 42.0 CLOCK

  8. Screening metal nanoparticles using boron-doped diamond microelectrodes

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

    Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Rangkuti, Prasmita K.; Einaga, Yasuaki

    2016-04-19

    Boron-doped diamond (BDD) microelectrodes were used to observe the correlation between electrocatalytic currents caused by individual Pt nanoparticle (Pt-np) collisions at the electrode. The BDD microelectrodes, ∼20 µm diameter and ∼2 µm particle size, were fabricated at the surface of tungsten wires. Pt-np with a size of 1 to 5 nm with agglomerations up to 20 nm was used for observation. The electrolytic currents were observed via catalytic reaction of 15 mM hydrazine in 50 mM phosphate buffer solution at Pt-np at 0.4 V when it collides with the surface of the microelectrodes. The low current noise and wider potential window in the measurements using BDD microelectrodemore » produced a better results, which represents a better correlation to the TEM result of the Pt-np, compared to when gold microelectrodes was used.« less

  9. Preparation of gold nanoparticles and determination of their particles size via different methods

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

    Iqbal, Muhammad; Usanase, Gisele; Oulmi, Kafia

    Graphical abstract: Preparation of gold nanoparticles via NaBH{sub 4} reduction method, and determination of their particle size, size distribution and morphology by using different techniques. - Highlights: • Gold nanoparticles were synthesized by NaBH{sub 4} reduction method. • Excess of reducing agent leads to tendency of aggregation. • The particle size, size distribution and morphology were investigated. • Particle size was determined both experimentally as well as theoretically. - Abstract: Gold nanoparticles have been used in various applications covering both electronics, biosensors, in vivo biomedical imaging and in vitro biomedical diagnosis. As a general requirement, gold nanoparticles should be preparedmore » in large scale, easy to be functionalized by chemical compound of by specific ligands or biomolecules. In this study, gold nanoparticles were prepared by using different concentrations of reducing agent (NaBH{sub 4}) in various formulations and their effect on the particle size, size distribution and morphology was investigated. Moreover, special attention has been dedicated to comparison of particles size measured by various techniques, such as, light scattering, transmission electron microscopy, UV spectrum using standard curve and particles size calculated by using Mie theory and UV spectrum of gold nanoparticles dispersion. Particle size determined by various techniques can be correlated for monodispersed particles and excess of reducing agent leads to increase in the particle size.« less

  10. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

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

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen

    2017-09-12

    Monodisperse particles having: a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology are disclosed. Due to their uniform size and shape, the monodisperse particles self assemble into superlattices. The particles may be luminescent particles such as down-converting phosphor particles and up-converting phosphors. The monodisperse particles of the invention have a rare earth-containing lattice which in one embodiment may be an yttrium-containing lattice or in another may be a lanthanide-containing lattice. The monodisperse particles may have different optical properties based on their composition, their size, and/or their morphology (or shape). Alsomore » disclosed is a combination of at least two types of monodisperse particles, where each type is a plurality of monodisperse particles having a single pure crystalline phase of a rare earth-containing lattice, a uniform three-dimensional size, and a uniform polyhedral morphology; and where the types of monodisperse particles differ from one another by composition, by size, or by morphology. In a preferred embodiment, the types of monodisperse particles have the same composition but different morphologies. Methods of making and methods of using the monodisperse particles are disclosed.« less

  11. Size limits for rounding of volcanic ash particles heated by lightning.

    PubMed

    Wadsworth, Fabian B; Vasseur, Jérémie; Llewellin, Edward W; Genareau, Kimberly; Cimarelli, Corrado; Dingwell, Donald B

    2017-03-01

    Volcanic ash particles can be remelted by the high temperatures induced in volcanic lightning discharges. The molten particles can round under surface tension then quench to produce glass spheres. Melting and rounding timescales for volcanic materials are strongly dependent on heating duration and peak temperature and are shorter for small particles than for large particles. Therefore, the size distribution of glass spheres recovered from ash deposits potentially record the short duration, high-temperature conditions of volcanic lightning discharges, which are hard to measure directly. We use a 1-D numerical solution to the heat equation to determine the timescales of heating and cooling of volcanic particles during and after rapid heating and compare these with the capillary timescale for rounding an angular particle. We define dimensionless parameters-capillary, Fourier, Stark, Biot, and Peclet numbers-to characterize the competition between heat transfer within the particle, heat transfer at the particle rim, and capillary motion, for particles of different sizes. We apply this framework to the lightning case and constrain a maximum size for ash particles susceptible to surface tension-driven rounding, as a function of lightning temperature and duration, and ash properties. The size limit agrees well with maximum sizes of glass spheres found in volcanic ash that has been subjected to lightning or experimental discharges, demonstrating that the approach that we develop can be used to obtain a first-order estimate of lightning conditions in volcanic plumes.

  12. Size limits for rounding of volcanic ash particles heated by lightning

    PubMed Central

    Vasseur, Jérémie; Llewellin, Edward W.; Genareau, Kimberly; Cimarelli, Corrado; Dingwell, Donald B.

    2017-01-01

    Abstract Volcanic ash particles can be remelted by the high temperatures induced in volcanic lightning discharges. The molten particles can round under surface tension then quench to produce glass spheres. Melting and rounding timescales for volcanic materials are strongly dependent on heating duration and peak temperature and are shorter for small particles than for large particles. Therefore, the size distribution of glass spheres recovered from ash deposits potentially record the short duration, high‐temperature conditions of volcanic lightning discharges, which are hard to measure directly. We use a 1‐D numerical solution to the heat equation to determine the timescales of heating and cooling of volcanic particles during and after rapid heating and compare these with the capillary timescale for rounding an angular particle. We define dimensionless parameters—capillary, Fourier, Stark, Biot, and Peclet numbers—to characterize the competition between heat transfer within the particle, heat transfer at the particle rim, and capillary motion, for particles of different sizes. We apply this framework to the lightning case and constrain a maximum size for ash particles susceptible to surface tension‐driven rounding, as a function of lightning temperature and duration, and ash properties. The size limit agrees well with maximum sizes of glass spheres found in volcanic ash that has been subjected to lightning or experimental discharges, demonstrating that the approach that we develop can be used to obtain a first‐order estimate of lightning conditions in volcanic plumes. PMID:28781929

  13. Size limits for rounding of volcanic ash particles heated by lightning

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian B.; Vasseur, Jérémie; Llewellin, Edward W.; Genareau, Kimberly; Cimarelli, Corrado; Dingwell, Donald B.

    2017-03-01

    Volcanic ash particles can be remelted by the high temperatures induced in volcanic lightning discharges. The molten particles can round under surface tension then quench to produce glass spheres. Melting and rounding timescales for volcanic materials are strongly dependent on heating duration and peak temperature and are shorter for small particles than for large particles. Therefore, the size distribution of glass spheres recovered from ash deposits potentially record the short duration, high-temperature conditions of volcanic lightning discharges, which are hard to measure directly. We use a 1-D numerical solution to the heat equation to determine the timescales of heating and cooling of volcanic particles during and after rapid heating and compare these with the capillary timescale for rounding an angular particle. We define dimensionless parameters—capillary, Fourier, Stark, Biot, and Peclet numbers—to characterize the competition between heat transfer within the particle, heat transfer at the particle rim, and capillary motion, for particles of different sizes. We apply this framework to the lightning case and constrain a maximum size for ash particles susceptible to surface tension-driven rounding, as a function of lightning temperature and duration, and ash properties. The size limit agrees well with maximum sizes of glass spheres found in volcanic ash that has been subjected to lightning or experimental discharges, demonstrating that the approach that we develop can be used to obtain a first-order estimate of lightning conditions in volcanic plumes.

  14. Radial particle-size segregation during packing of particulates into cylindrical containers

    USGS Publications Warehouse

    Ripple, C.D.; James, R.V.; Rubin, J.

    1973-01-01

    In a series of experiments, soil materials were placed in long cylindrical containers, using various packing procedures. Soil columns produced by deposition and simultaneous vibratory compaction were dense and axially uniform, but showed significant radial segregation of particle sizes. Similar results were obtained with deposition and simultaneous impact-type compaction when the impacts resulted in significant container "bouncing". The latter procedure, modified to minimize "bouncing" produced dense, uniform soil columns, showing little radial particle-size segregation. Other procedures tested (deposition alone and deposition followed by compaction) did not result in radial segregation, but produced columns showing either relatively low or axially nonuniform densities. Current data suggest that radial particle-size segregation is mainly due to vibration-induced particle circulation in which particles of various sizes have different circulation rates and paths. ?? 1973.

  15. Effect of particle size of parenteral suspensions on in vitro muscle damage.

    PubMed

    Brazeau, Gayle; Sauberan, Shauna L; Gatlin, Larry; Wisniecki, Peter; Shah, Jaymin

    2011-01-01

    Suspension particle size plays a key role in the release and stability of drugs for oral and parenteral formulations. However, the role of particle size in suspension formulations on tissue damage (myotoxicity) following intramuscular (IM) injection has not been systematically investigated. Myotoxicity was assessed by the release of cumulative creatine kinase (CCK) from the isolated extensor digitorium longus (EDL) and soleus (SOL) rat muscles for selected suspensions of phenytoin, bupivicane and diazepam. Particle size effects on myotoxicity, independent of any specific drug, were also investigated using characterized non-dissolving polystyrene beads. Myotoxicity was quantitated by the cumulative release of creatine kinase (CCK) from these isolated muscles over 90 or 120 min. The relationship between particle size and myotoxicity was dependent upon the drug in these suspensions. Diazepam and phenytoin suspensions were found to be less myotoxic than bupivicaine. Using unmodified and carboxy modified polystyrene beads, an optimal particle size for reduced myotoxicity following IM injection ranges from approx. 500 nm to 1 µM. The relationship between myotoxicity of IM suspensions and particle size is dependent upon the particular drug and suspension particle size.

  16. The effect of particle size on the morphology and thermodynamics of diblock copolymer/tethered-particle membranes

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

    Zhang, Bo; Edwards, Brian J., E-mail: bje@utk.edu

    A combination of self-consistent field theory and density functional theory was used to examine the effect of particle size on the stable, 3-dimensional equilibrium morphologies formed by diblock copolymers with a tethered nanoparticle attached either between the two blocks or at the end of one of the blocks. Particle size was varied between one and four tenths of the radius of gyration of the diblock polymer chain for neutral particles as well as those either favoring or disfavoring segments of the copolymer blocks. Phase diagrams were constructed and analyzed in terms of thermodynamic diagrams to understand the physics associated withmore » the molecular-level self-assembly processes. Typical morphologies were observed, such as lamellar, spheroidal, cylindrical, gyroidal, and perforated lamellar, with the primary concentration region of the tethered particles being influenced heavily by particle size and tethering location, strength of the particle-segment energetic interactions, chain length, and copolymer radius of gyration. The effect of the simulation box size on the observed morphology and system thermodynamics was also investigated, indicating possible effects of confinement upon the system self-assembly processes.« less

  17. Measurement of non-volatile particle number size distribution

    NASA Astrophysics Data System (ADS)

    Gkatzelis, G. I.; Papanastasiou, D. K.; Florou, K.; Kaltsonoudis, C.; Louvaris, E.; Pandis, S. N.

    2015-06-01

    An experimental methodology was developed to measure the non-volatile particle number concentration using a thermodenuder (TD). The TD was coupled with a high-resolution time-of-flight aerosol mass spectrometer, measuring the chemical composition and mass size distribution of the submicrometer aerosol and a scanning mobility particle sizer (SMPS) that provided the number size distribution of the aerosol in the range from 10 to 500 nm. The method was evaluated with a set of smog chamber experiments and achieved almost complete evaporation (> 98 %) of secondary organic as well as freshly nucleated particles, using a TD temperature of 400 °C and a centerline residence time of 15 s. This experimental approach was applied in a winter field campaign in Athens and provided a direct measurement of number concentration and size distribution for particles emitted from major pollution sources. During periods in which the contribution of biomass burning sources was dominant, more than 80 % of particle number concentration remained after passing through the thermodenuder, suggesting that nearly all biomass burning particles had a non-volatile core. These remaining particles consisted mostly of black carbon (60 % mass contribution) and organic aerosol, OA (40 %). Organics that had not evaporated through the TD were mostly biomass burning OA (BBOA) and oxygenated OA (OOA) as determined from AMS source apportionment analysis. For periods during which traffic contribution was dominant 50-60 % of the particles had a non-volatile core while the rest evaporated at 400 °C. The remaining particle mass consisted mostly of black carbon (BC) with an 80 % contribution, while OA was responsible for another 15-20 %. Organics were mostly hydrocarbon-like OA (HOA) and OOA. These results suggest that even at 400 °C some fraction of the OA does not evaporate from particles emitted from common combustion processes, such as biomass burning and car engines, indicating that a fraction of this type

  18. Particle Number Concentrations for HI-SCALE Field Campaign Report

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

    Hering, Susanne V

    In support of the Holistic Interactions of Shallow Clouds, Aerosols, and Ecosystems (HI-SCALE) project to study new particle formation in the atmosphere, a pair of custom water condensation particle counters were provided to the second intensive field campaign, from mid-August through mid-September 2017, at the U.S. Department of Energy Southern Great Plains Atmospheric Radiation Measurement (ARM) Climate Research Facility observatory. These custom instruments were developed by Aerosol Dynamics, Inc. (Hering et al. 2017) to detect particles into the nanometer size range. Referred to as “versatile water condensation particle counter (vWCPC)”, they are water-based, laminar-flow condensational growth instruments whose lower particlemore » size threshold can be set based on user-selected operating temperatures. For HI-SCALE, the vWCPCs were configured to measure airborne particle number concentrations in the size range from approximately 2nm to 2μm. Both were installed in the particle sizing system operated by Chongai Kuang of Brookhaven National Laboratory (BNL). One of these was operated in parallel to a TSI Model 3776, upstream of the mobility particle sizing system, to measure total ambient particle concentrations. The airborne particle concentration data from this “total particle number vWCPC” (Ntot-vWCPC) system has been reported to the ARM database. The data are reported with one-second resolution. The second vWCPC was operated in parallel with the BNL diethylene glycol instrument to count particles downstream of a separate differential mobility size analyzer. Data from this “DMA-vWCPC” system was logged by BNL, and will eventually be provided by that laboratory.« less

  19. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens.

    PubMed

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-03-02

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

  20. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

    NASA Astrophysics Data System (ADS)

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-03-01

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated.

  1. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

    PubMed Central

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-01-01

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated. PMID:28252033

  2. Nanometer-sized extracellular matrix coating on polymer-based scaffold for tissue engineering applications.

    PubMed

    Uchida, Noriyuki; Sivaraman, Srikanth; Amoroso, Nicholas J; Wagner, William R; Nishiguchi, Akihiro; Matsusaki, Michiya; Akashi, Mitsuru; Nagatomi, Jiro

    2016-01-01

    Surface modification can play a crucial role in enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering applications. Here, we report a novel approach for layer-by-layer (LbL) fabrication of nanometer-size fibronectin and gelatin (FN-G) layers on electrospun fibrous poly(carbonate urethane)urea (PCUU) scaffolds. Alternate immersions into the solutions of fibronectin and gelatin provided thickness-controlled FN-G nano-layers (PCUU(FN-G) ) which maintained the scaffold's 3D structure and width of fibrous bundle of PCUU as evidenced by scanning electron miscroscopy. The PCUU(FN-G) scaffold improved cell adhesion and proliferation of bladder smooth muscles (BSMCs) when compared to uncoated PCUU. The high affinity of PCUU(FN-G) for cells was further demonstrated by migration of adherent BSMCs from culture plates to the scaffold. Moreover, the culture of UROtsa cells, human urothelium-derived cell line, on PCUU(FN-G) resulted in an 11-15 μm thick multilayered cell structure with cell-to-cell contacts although many UROtsa cells died without forming cell connections on PCUU. Together these results indicate that this approach will aid in advancing the technology for engineering bladder tissues in vitro. Because FN-G nano-layers formation is based on nonspecific physical adsorption of fibronectin onto polymer and its subsequent interactions with gelatin, this technique may be applicable to other polymer-based scaffold systems for various tissue engineering/regenerative medicine applications. © 2015 Wiley Periodicals, Inc.

  3. Particle size and particle-particle interactions on tensile properties and reinforcement of corn flour particles in natural rubber

    USDA-ARS?s Scientific Manuscript database

    Renewable corn flour has a significant reinforcement effect in natural rubber. The corn flour was hydrolyzed and microfluidized to reduce its particle size. Greater than 90% of the hydrolyzed corn flour had an average size of ~300 nm, a reduction of 33 times compared to unhydrolyzed corn flour. Comp...

  4. Dust generation in powders: Effect of particle size distribution

    NASA Astrophysics Data System (ADS)

    Chakravarty, Somik; Le Bihan, Olivier; Fischer, Marc; Morgeneyer, Martin

    2017-06-01

    This study explores the relationship between the bulk and grain-scale properties of powders and dust generation. A vortex shaker dustiness tester was used to evaluate 8 calcium carbonate test powders with median particle sizes ranging from 2μm to 136μm. Respirable aerosols released from the powder samples were characterised by their particle number and mass concentrations. All the powder samples were found to release respirable fractions of dust particles which end up decreasing with time. The variation of powder dustiness as a function of the particle size distribution was analysed for the powders, which were classified into three groups based on the fraction of particles within the respirable range. The trends we observe might be due to the interplay of several mechanisms like de-agglomeration and attrition and their relative importance.

  5. Nature of alpha and beta particles in glycogen using molecular size distributions.

    PubMed

    Sullivan, Mitchell A; Vilaplana, Francisco; Cave, Richard A; Stapleton, David; Gray-Weale, Angus A; Gilbert, Robert G

    2010-04-12

    Glycogen is a randomly hyperbranched glucose polymer. Complex branched polymers have two structural levels: individual branches and the way these branches are linked. Liver glycogen has a third level: supramolecular clusters of beta particles which form larger clusters of alpha particles. Size distributions of native glycogen were characterized using size exclusion chromatography (SEC) to find the number and weight distributions and the size dependences of the number- and weight-average masses. These were fitted to two distinct randomly joined reference structures, constructed by random attachment of individual branches and as random aggregates of beta particles. The z-average size of the alpha particles in dimethylsulfoxide does not change significantly with high concentrations of LiBr, a solvent system that would disrupt hydrogen bonding. These data reveal that the beta particles are covalently bonded to form alpha particles through a hitherto unsuspected enzyme process, operative in the liver on particles above a certain size range.

  6. Mass-specific scattering coefficient for natural minerogenic particle populations: particle size distribution effect and closure analyses.

    PubMed

    Peng, Feng; Effler, Steve W

    2012-05-01

    The relationship between the particulate scattering coefficient (b(p)) and the concentration of suspended particulate matter (SPM), as represented by the mass-specific scattering coefficient of particulates (b(p)*=b(p)/SPM), depends on particle size distribution (PSD). This dependence is quantified for minerogenic particle populations in this paper through calculations of b(p)* for common minerals as idealized populations (monodispersed spheres); contemporaneous measurements of b(p), SPM, and light-scattering attributes of mineral particles with scanning electron microscopy interfaced with automated image and x-ray analyses (SAX), for a connected stream-reservoir system where minerogenic particles dominate b(p); and estimates of b(p) and its size dependency (through SAX results-driven Mie theory calculations), particle volume concentration, and b(p)*. Modest changes in minerogenic PSDs are shown to result in substantial variations in b(p)*. Good closure of the SAX-based estimates of b(p) and particle volume concentration with bulk measurements is demonstrated. Converging relationships between b(p)* and particle size, developed from three approaches, were well described by power law expressions.

  7. Quantitative Reflectance Spectra of Solid Powders as a Function of Particle Size

    DOE PAGES

    Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; ...

    2015-05-19

    We have recently developed vetted methods for obtaining quantitative infrared directional-hemispherical reflectance spectra using a commercial integrating sphere. In this paper, the effects of particle size on the spectral properties are analyzed for several samples such as ammonium sulfate, calcium carbonate, and sodium sulfate as well as one organic compound, lactose. We prepared multiple size fractions for each sample and confirmed the mean sizes using optical microscopy. Most species displayed a wide range of spectral behavior depending on the mean particle size. General trends of reflectance vs. particle size are observed such as increased albedo for smaller particles: for mostmore » wavelengths, the reflectivity drops with increased size, sometimes displaying a factor of 4 or more drop in reflectivity along with a loss of spectral contrast. In the longwave infrared, several species with symmetric anions or cations exhibited reststrahlen features whose amplitude was nearly invariant with particle size, at least for intermediate- and large-sized sample fractions; that is, > ~150 microns. Trends of other types of bands (Christiansen minima, transparency features) are also investigated as well as quantitative analysis of the observed relationship between reflectance vs. particle diameter.« less

  8. Quantitative Reflectance Spectra of Solid Powders as a Function of Particle Size

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

    Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong

    We have recently developed vetted methods for obtaining quantitative infrared directional-hemispherical reflectance spectra using a commercial integrating sphere. In this paper, the effects of particle size on the spectral properties are analyzed for several samples such as ammonium sulfate, calcium carbonate, and sodium sulfate as well as one organic compound, lactose. We prepared multiple size fractions for each sample and confirmed the mean sizes using optical microscopy. Most species displayed a wide range of spectral behavior depending on the mean particle size. General trends of reflectance vs. particle size are observed such as increased albedo for smaller particles: for mostmore » wavelengths, the reflectivity drops with increased size, sometimes displaying a factor of 4 or more drop in reflectivity along with a loss of spectral contrast. In the longwave infrared, several species with symmetric anions or cations exhibited reststrahlen features whose amplitude was nearly invariant with particle size, at least for intermediate- and large-sized sample fractions; that is, > ~150 microns. Trends of other types of bands (Christiansen minima, transparency features) are also investigated as well as quantitative analysis of the observed relationship between reflectance vs. particle diameter.« less

  9. Forces acting on a small particle in an acoustical field in a thermoviscous fluid.

    PubMed

    Karlsen, Jonas T; Bruus, Henrik

    2015-10-01

    We present a theoretical analysis of the acoustic radiation force on a single small spherical particle, either a thermoviscous fluid droplet or a thermoelastic solid particle, suspended in a viscous and heat-conducting fluid medium. Within the perturbation assumptions, our analysis places no restrictions on the length scales of the viscous and thermal boundary-layer thicknesses δ(s) and δ(t) relative to the particle radius a, but it assumes the particle to be small in comparison to the acoustic wavelength λ. This is the limit relevant to scattering of ultrasound waves from nanometer- and micrometer-sized particles. For particles of size comparable to or smaller than the boundary layers, the thermoviscous theory leads to profound consequences for the acoustic radiation force. Not only do we predict forces orders of magnitude larger than expected from ideal-fluid theory, but for certain relevant choices of materials, we also find a sign change in the acoustic radiation force on different-sized but otherwise identical particles. These findings lead to the concept of a particle-size-dependent acoustophoretic contrast factor, highly relevant to acoustic separation of microparticles in gases, as well as to handling of nanoparticles in lab-on-a-chip systems.

  10. Forces acting on a small particle in an acoustical field in a thermoviscous fluid

    NASA Astrophysics Data System (ADS)

    Karlsen, Jonas T.; Bruus, Henrik

    2015-10-01

    We present a theoretical analysis of the acoustic radiation force on a single small spherical particle, either a thermoviscous fluid droplet or a thermoelastic solid particle, suspended in a viscous and heat-conducting fluid medium. Within the perturbation assumptions, our analysis places no restrictions on the length scales of the viscous and thermal boundary-layer thicknesses δs and δt relative to the particle radius a , but it assumes the particle to be small in comparison to the acoustic wavelength λ . This is the limit relevant to scattering of ultrasound waves from nanometer- and micrometer-sized particles. For particles of size comparable to or smaller than the boundary layers, the thermoviscous theory leads to profound consequences for the acoustic radiation force. Not only do we predict forces orders of magnitude larger than expected from ideal-fluid theory, but for certain relevant choices of materials, we also find a sign change in the acoustic radiation force on different-sized but otherwise identical particles. These findings lead to the concept of a particle-size-dependent acoustophoretic contrast factor, highly relevant to acoustic separation of microparticles in gases, as well as to handling of nanoparticles in lab-on-a-chip systems.

  11. Combinative Particle Size Reduction Technologies for the Production of Drug Nanocrystals

    PubMed Central

    Salazar, Jaime; Müller, Rainer H.; Möschwitzer, Jan P.

    2014-01-01

    Nanosizing is a suitable method to enhance the dissolution rate and therefore the bioavailability of poorly soluble drugs. The success of the particle size reduction processes depends on critical factors such as the employed technology, equipment, and drug physicochemical properties. High pressure homogenization and wet bead milling are standard comminution techniques that have been already employed to successfully formulate poorly soluble drugs and bring them to market. However, these techniques have limitations in their particle size reduction performance, such as long production times and the necessity of employing a micronized drug as the starting material. This review article discusses the development of combinative methods, such as the NANOEDGE, H 96, H 69, H 42, and CT technologies. These processes were developed to improve the particle size reduction effectiveness of the standard techniques. These novel technologies can combine bottom-up and/or top-down techniques in a two-step process. The combinative processes lead in general to improved particle size reduction effectiveness. Faster production of drug nanocrystals and smaller final mean particle sizes are among the main advantages. The combinative particle size reduction technologies are very useful formulation tools, and they will continue acquiring importance for the production of drug nanocrystals. PMID:26556191

  12. Recovering 3D particle size distributions from 2D sections

    NASA Astrophysics Data System (ADS)

    Cuzzi, Jeffrey N.; Olson, Daniel M.

    2017-03-01

    We discuss different ways to convert observed, apparent particle size distributions from 2D sections (thin sections, SEM maps on planar surfaces, etc.) into true 3D particle size distributions. We give a simple, flexible, and practical method to do this; show which of these techniques gives the most faithful conversions; and provide (online) short computer codes to calculate both 2D-3D recoveries and simulations of 2D observations by random sectioning. The most important systematic bias of 2D sectioning, from the standpoint of most chondrite studies, is an overestimate of the abundance of the larger particles. We show that fairly good recoveries can be achieved from observed size distributions containing 100-300 individual measurements of apparent particle diameter.

  13. Rock sampling. [method for controlling particle size distribution

    NASA Technical Reports Server (NTRS)

    Blum, P. (Inventor)

    1971-01-01

    A method for sampling rock and other brittle materials and for controlling resultant particle sizes is described. The method involves cutting grooves in the rock surface to provide a grouping of parallel ridges and subsequently machining the ridges to provide a powder specimen. The machining step may comprise milling, drilling, lathe cutting or the like; but a planing step is advantageous. Control of the particle size distribution is effected primarily by changing the height and width of these ridges. This control exceeds that obtainable by conventional grinding.

  14. The origins of particle size effects in heterogeneous catalysis

    NASA Astrophysics Data System (ADS)

    Bond, Geoffrey C.

    1985-06-01

    Model calculations are presented to show how the fraction of atoms at the surface of small metal particles increases as their size diminishes in the range 10 to 2 nm. Such particles are prepared either by condensing atoms or aggregates from the vapour phase onto a support, or by chemical methods in the liquid phase, i.e. the traditional routes for preparing supported metal catalysts. The first group of methods leads to artificially pure materials in which the contact between metal and support is poor. The second group of methods leads to the introduction of impurities, to a greater variety of forms of particle, but to a generally firmer binding of metal to support: this permits electronic interactions between the components to occur. Recent literature on the chemisorptive and catalytic properties of metal particles, usually less than 10 nm in size, suggests that certain classes of reaction may be designated as "structure-insensitive" in that their rates depend only minimally on particle size, whereas others, denoted as "structure-sensitive", have rates which either increase or decrease with size. After discounting trivial effects, a hard core of results remains, demanding explanation. Although certain hydrocarbon transformations appear to need sites comprising more than a certain minimum number of atoms, it is thought that the electronic character of surface atoms plays a greater role than their geometric disposition.

  15. Diagnostic Techniques Used to Study Chemical-Vapor-Deposited Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2000-01-01

    The advantages and utility of chemical-vapor-deposited (CVD) diamond as an industrial ceramic can only be realized if the price and quality are right. Until recently, this technology was of interest only to the academic and basic research community. However, interest has grown because of advances made by leading CVD diamond suppliers: 1) Reduction of the cost of CVD polycrystalline diamond deposition below $5/carat ($8/sq cm); 2) Installation of production capacity; 3) Epitaxial growth of CVD single-crystal diamond. Thus, CVD diamond applications and business are an industrial reality. At present, CVD diamond is produced in the form of coatings or wafers. CVD diamond film technology offers a broader technological potential than do natural and high-pressure synthetic diamonds because size, geometry, and eventually cost will not be as limiting. Now that they are cost effective, diamond coatings - with their extreme properties - can be used in a variety of applications. Diamond coatings can improve many of the surface properties of engineering substrate materials, including erosion, corrosion, and wear resistance. Examples of actual and potential applications, from microelectromechanical systems to the wear parts of diamond coatings and related superhard coatings are described. For example, diamond coatings can be used as a chemical and mechanical barrier for the space shuttles check valves, particularly on the guide pins and seat assemblies.

  16. Fabrication, characterization, and potential application of carbon fiber cone nanometer-size electrodes.

    PubMed

    Zhang, X; Zhang, W; Zhou, X; Ogorevc, B

    1996-10-01

    A novel method has been developed for the fabrication of carbon fiber cone nanometer-size ultramicroelectrodes (nanoelectrodes) with overall tip dimensions as small as 50 nm in diameter. In this method, carbon fibers were initially etched by an argon ion beam thinner. Afterward, a single etched carbon fiber was inserted into a glass capillary, which was then sealed by heating the glass/fiber interface in a vacuum; thus, no epoxy resin is involved. The success rate of our fabrication route for the electrodes with overall tip diameters of up to 500 nm was about 80%; for those with tip diameters of up to 100 nm, it was about 50%. The fabricated carbon fiber cone nanoelectrodes (CFCNEs) were inspected by optical and scanning electron microscopy. Their electrochemical behavior was examined by cyclic and linear sweep voltammetric measurements of ferricyanide and ferrocene ions in aqueous and nonaqueous media. The potential analytical applicability of the CFCNEs was tested by differential pulse voltammetric measurements of two well-known neurotransmitters, dopamine (DA) and 5-hydroxytryptamine (5-HT), and the results achieved were highly satisfactory. The calibration plots obtained were linear over the ranges from 5.0 × 10(-7) to 1.0 × 10(-4) and from 2.0 × 10(-6) to 1.0 × 10(-4) mol/L, with limits of detection of 1.0 × 10(-7) and 5.0 × 10(-7) mol/L for DA and 5-HT, respectively. Some advantages and improvements of the proposed CFCNE fabrication method, especially with respect to smoothness of the fiber (electrode) surface, strength, and control over the fiber tip dimensions, are also discussed.

  17. 'Diamond Jenness': After the Grind

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This microscopic imager mosaic taken by NASA's Mars Exploration Rover Opportunity shows the rock dubbed 'Diamond Jenness.' It was taken on sol 177 (July 23, 2004) after the rover first ground into the rock with its rock abrasion tool, or 'Rat.' The rover later ground into the rock a second time. A sliced spherule, or 'blueberry,' is visible in the upper left corner of the hole.

    Opportunity has bored nearly a dozen holes into the inner walls of 'Endurance Crater.' On sols 177 and 178 (July 23 and July 24, 2004), the rover worked double-duty on Diamond Jenness. Surface debris and the bumpy shape of the rock resulted in a shallow and irregular hole, only about 2 millimeters (0.08 inch) deep. The final depth was not enough to remove all the bumps and leave a neat hole with a smooth floor. This extremely shallow depression was then examined by the rover's alpha particle X-ray spectrometer.

    On Sol 178, Opportunity's 'robotic rodent' dined on Diamond Jenness once again, grinding almost an additional 5 millimeters (about 0.2 inch). The rover then applied its Moessbauer spectrometer to the deepened hole. This double dose of Diamond Jenness enabled the science team to examine the rock at varying layers. Results from those grindings are currently being analyzed.

    The image mosaic is about 6 centimeters (2.4 inches) across.

  18. Fabrication of microchannels in polycrystalline diamond using pre-fabricated Si substrates

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Elfimchev, Sergey; Michaelson, Shaul; Akhvlediani, Rozalia; Ternyak, Orna; Hoffman, Alon

    2017-10-01

    In this paper, we report on a simple, feasible method to fabricate microchannels in diamond. Polycrystalline diamond microchannels were produced by fabricating trenches in a Si wafer and subsequently depositing a thin layer of diamond onto this substrate using the hot filament vapor deposition technique. Fabrication of trenches in the Si substrate at different depths was carried out by standard photolithography, and the subsequent deposition of the diamond layer was performed by the hot filament chemical vapor deposition technique. The growth mechanism of diamond that leads to the formation of closed diamond microchannels is discussed in detail based on the Knudsen number and growth chemistry of diamond. Variations in the crystallite size, crystalline quality, and thickness of the diamond layer along the trench depths were systematically analyzed using cross-sectional scanning electron microscopy and Raman spectroscopy. Defect density and formation of non-diamond forms of carbon in the diamond layer were found to increase with the trench depth, which sets a limit of 5-45 μm trench depth (or an aspect ratio of 1-9) for the fabrication of diamond microchannels using this method under the present conditions.

  19. Half-heusler alloys with enhanced figure of merit and methods of making

    DOEpatents

    Ren, Zhifeng; Yan, Xiao; Joshi, Giri; Chen, Shuo; Chen, Gang; Poudel, Bed; Caylor, James Christopher

    2015-06-02

    Thermoelectric materials and methods of making thermoelectric materials having a nanometer mean grain size less than 1 micron. The method includes combining and arc melting constituent elements of the thermoelectric material to form a liquid alloy of the thermoelectric material and casting the liquid alloy of the thermoelectric material to form a solid casting of the thermoelectric material. The method also includes ball milling the solid casting of the thermoelectric material into nanometer mean size particles and sintering the nanometer size particles to form the thermoelectric material having nanometer scale mean grain size.

  20. Effects of Particle Size on the Attenuated Total Reflection Spectrum of Minerals.

    PubMed

    Udvardi, Beatrix; Kovács, István J; Fancsik, Tamás; Kónya, Péter; Bátori, Miklósné; Stercel, Ferenc; Falus, György; Szalai, Zoltán

    2017-06-01

    This study focuses on particle size effect on monomineralic powders recorded using attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy. Six particle size fractions of quartz, feldspar, calcite, and dolomite were prepared (<2, 2-4, 4-8, 8-16, 16-32, and 32-63 µm). It is found that the width, intensity, and area of bands in the ATR FT-IR spectra of minerals have explicit dependence on the particle size. As particle size increases, the intensity and area of IR bands usually decrease while the width of bands increases. The band positions usually shifted to higher wavenumbers with decreasing particle size. Infrared spectra of minerals are the most intensive in the particle size fraction of 2-4 µm. However, if the particle size is very small (<2 µm), due to the wavelength and penetration depth of the IR light, intensity decreases. Therefore, the quantity of very fine-grained minerals may be underestimated compared to the coarser phases. A nonlinear regression analysis of the data indicated that the average coefficients and indices of the power trend line equation imply a very simplistic relationship between median particle diameter and absorbance at a given wavenumber. It is concluded that when powder samples with substantially different particle size are compared, as in regression analysis for modal predictions using ATR FT-IR, it is also important to report the grain size distribution or surface area of samples. The band area of water (3000-3620 cm -1 ) is similar in each mineral fraction, except for the particles below 2 µm. It indicates that the finest particles could have disproportionately more water adsorbed on their larger surface area. Thus, these higher wavenumbers of the ATR FT-IR spectra may be more sensitive to this spectral interference if the number of particles below 2 µm is considerable. It is also concluded that at least a proportion of the moisture could be very adhesive to the particles due to the band

  1. Diamond thin film temperature and heat-flux sensors

    NASA Technical Reports Server (NTRS)

    Aslam, M.; Yang, G. S.; Masood, A.; Fredricks, R.

    1995-01-01

    Diamond film temperature and heat-flux sensors are developed using a technology compatible with silicon integrated circuit processing. The technology involves diamond nucleation, patterning, doping, and metallization. Multi-sensor test chips were designed and fabricated to study the thermistor behavior. The minimum feature size (device width) for 1st and 2nd generation chips are 160 and 5 micron, respectively. The p-type diamond thermistors on the 1st generation test chip show temperature and response time ranges of 80-1270 K and 0.29-25 microseconds, respectively. An array of diamond thermistors, acting as heat flux sensors, was successfully fabricated on an oxidized Si rod with a diameter of 1 cm. Some problems were encountered in the patterning of the Pt/Ti ohmic contacts on the rod, due mainly to the surface roughness of the diamond film. The use of thermistors with a minimum width of 5 micron (to improve the spatial resolution of measurement) resulted in lithographic problems related to surface roughness of diamond films. We improved the mean surface roughness from 124 nm to 30 nm by using an ultra high nucleation density of 10(exp 11)/sq cm. To deposit thermistors with such small dimensions on a curved surface, a new 3-D diamond patterning technique is currently under development. This involves writing a diamond seed pattern directly on the curved surface by a computer-controlled nozzle.

  2. Modeling photoacoustic spectral features of micron-sized particles

    NASA Astrophysics Data System (ADS)

    Strohm, Eric M.; Gorelikov, Ivan; Matsuura, Naomi; Kolios, Michael C.

    2014-10-01

    The photoacoustic signal generated from particles when irradiated by light is determined by attributes of the particle such as the size, speed of sound, morphology and the optical absorption coefficient. Unique features such as periodically varying minima and maxima are observed throughout the photoacoustic signal power spectrum, where the periodicity depends on these physical attributes. The frequency content of the photoacoustic signals can be used to obtain the physical attributes of unknown particles by comparison to analytical solutions of homogeneous symmetric geometric structures, such as spheres. However, analytical solutions do not exist for irregularly shaped particles, inhomogeneous particles or particles near structures. A finite element model (FEM) was used to simulate photoacoustic wave propagation from four different particle configurations: a homogeneous particle suspended in water, a homogeneous particle on a reflecting boundary, an inhomogeneous particle with an absorbing shell and non-absorbing core, and an irregularly shaped particle such as a red blood cell. Biocompatible perfluorocarbon droplets, 3-5 μm in diameter containing optically absorbing nanoparticles were used as the representative ideal particles, as they are spherical, homogeneous, optically translucent, and have known physical properties. The photoacoustic spectrum of micron-sized single droplets in suspension and on a reflecting boundary were measured over the frequency range of 100-500 MHz and compared directly to analytical models and the FEM. Good agreement between the analytical model, FEM and measured values were observed for a droplet in suspension, where the spectral minima agreed to within a 3.3 MHz standard deviation. For a droplet on a reflecting boundary, spectral features were correctly reproduced using the FEM but not the analytical model. The photoacoustic spectra from other common particle configurations such as particle with an absorbing shell and a

  3. Performance of irradiated CVD diamond micro-strip sensors

    NASA Astrophysics Data System (ADS)

    Adam, W.; Berdermann, E.; Bergonzo, P.; Bertuccio, G.; Bogani, F.; Borchi, E.; Brambilla, A.; Bruzzi, M.; Colledani, C.; Conway, J.; D'Angelo, P.; Dabrowski, W.; Delpierre, P.; Deneuville, A.; Dulinski, W.; van Eijk, B.; Fallou, A.; Fizzotti, F.; Foulon, F.; Friedl, M.; Gan, K. K.; Gheeraert, E.; Hallewell, G.; Han, S.; Hartjes, F.; Hrubec, J.; Husson, D.; Kagan, H.; Kania, D.; Kaplon, J.; Kass, R.; Koeth, T.; Krammer, M.; Logiudice, A.; Lu, R.; mac Lynne, L.; Manfredotti, C.; Meier, D.; Mishina, M.; Moroni, L.; Noomen, J.; Oh, A.; Pan, L. S.; Pernicka, M.; Peitz, A.; Perera, L.; Pirollo, S.; Procario, M.; Riester, J. L.; Roe, S.; Rousseau, L.; Rudge, A.; Russ, J.; Sala, S.; Sampietro, M.; Schnetzer, S.; Sciortino, S.; Stelzer, H.; Stone, R.; Suter, B.; Tapper, R. J.; Tesarek, R.; Trischuk, W.; Tromson, D.; Vittone, E.; Walsh, A. M.; Wedenig, R.; Weilhammer, P.; Wetstein, M.; White, C.; Zeuner, W.; Zoeller, M.; Plano, R.; Somalwar, S. V.; Thomson, G. B.

    2002-01-01

    CVD diamond detectors are of interest for charged particle detection and tracking due to their high radiation tolerance. In this article, we present, for the first time, beam test results from recently manufactured CVD diamond strip detectors and their behavior under low doses of electrons from a β-source and the performance before and after intense (>10 15/cm 2) proton- and pion-irradiations. We find that low dose irradiation increase the signal-to-noise ratio (pumping of the signal) and slightly deteriorate the spatial resolution. Intense irradiation with protons 2.2×10 15 p/ cm2 lowers the signal-to-noise ratio slightly. Intense irradiation with pions 2.9×10 15 π/ cm2 lowers the signal-to-noise ratio more. The spatial resolution of the diamond sensors improves after irradiations.

  4. Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

    NASA Astrophysics Data System (ADS)

    Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

    2017-11-01

    Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

  5. Production of large-particle-size monodisperse latexes

    NASA Technical Reports Server (NTRS)

    Vanderhoff, J. W.; El-Aasser, M. L.; Micale, F. J.; Sudol, E. D.; Tseng, C. M.; Silwanowicz, A.

    1984-01-01

    The research program achieved two objectives: (1) it has refined and extended the experimental techniques for preparing monodisperse latexes in quantity on the ground up to a particle diameter of 10 microns; and (2) it has demonstrated that a microgravity environment can be used to grow monodisperse latexes to larger sizes, where the limitations in size have yet to be defined. The experimental development of the monodisperse latex reactor (MLR) and the seeded emulsion polymerizations carried out in the laboratory prototype of the flight hardware, as a function of the operational parameters is discussed. The emphasis is directed towards the measurement, interpretation, and modeling of the kinetics of seeded emulsion polymerization and successive seeded emulsion polymerization. The recipe development of seeded emulsion polymerization as a function of particle size is discussed. The equilibrium swelling of latex particles with monomers was investigated both theoretically and experimentally. Extensive studies are reported on both the type and concentration of initiators, surfactants, and inhibitors, which eventually led to the development of the flight recipes. The experimental results of the flight experiments are discussed, as well as the experimental development of inhibition of seeded emulsion polymerization in terms of time of inhibition and the effect of inhibitors on the kinetics of polymerization.

  6. Synthesis and characterization of magnetic and non-magnetic core-shell polyepoxide micrometer-sized particles of narrow size distribution.

    PubMed

    Omer-Mizrahi, Melany; Margel, Shlomo

    2009-01-15

    Core polystyrene microspheres of narrow size distribution were prepared by dispersion polymerization of styrene in a mixture of ethanol and 2-methoxy ethanol. Uniform polyglycidyl methacrylate/polystyrene core-shell micrometer-sized particles were prepared by emulsion polymerization at 73 degrees C of glycidyl methacrylate in the presence of the core polystyrene microspheres. Core-shell particles with different properties (size, surface morphology and composition) have been prepared by changing various parameters belonging to the above seeded emulsion polymerization process, e.g., volumes of the monomer glycidyl methacrylate and the crosslinker monomer ethylene glycol dimethacrylate. Magnetic Fe(3)O(4)/polyglycidyl methacrylate/polystyrene micrometer-sized particles were prepared by coating the former core-shell particles with magnetite nanoparticles via a nucleation and growth mechanism. Characterization of the various particles has been accomplished by routine methods such as light microscopy, SEM, FTIR, BET and magnetic measurements.

  7. Particle size distributions from laboratory-scale biomass fires using fast response instruments

    Treesearch

    S Hosseini; L. Qi; D. Cocker; D. Weise; A. Miller; M. Shrivastava; J.W. Miller; S. Mahalingam; M. Princevac; H. Jung

    2010-01-01

    Particle size distribution from biomass combustion is an important parameter as it affects air quality, climate modelling and health effects. To date, particle size distributions reported from prior studies vary not only due to difference in fuels but also difference in experimental conditions. This study aims to report characteristics of particle size distributions in...

  8. Using portable particle sizing instrumentation to rapidly measure the penetration of fine and ultrafine particles in unoccupied residences.

    PubMed

    Zhao, H; Stephens, B

    2017-01-01

    Much of human exposure to particulate matter of outdoor origin occurs inside buildings, particularly in residences. The particle penetration factor through leaks in a building's exterior enclosure assembly is a key parameter that governs the infiltration of outdoor particles. However, experimental data for size-resolved particle penetration factors in real buildings, as well as penetration factors for fine particles less than 2.5 μm (PM 2.5 ) and ultrafine particles less than 100 nm (UFPs), remain limited, in part because of previous limitations in instrumentation and experimental methods. Here, we report on the development and application of a modified test method that utilizes portable particle sizing instrumentation to measure size-resolved infiltration factors and envelope penetration factors for 0.01-2.5 μm particles, which are then used to estimate penetration factors for integral measures of UFPs and PM 2.5 . Eleven replicate measurements were made in an unoccupied apartment unit in Chicago, IL to evaluate the accuracy and repeatability of the test procedure and solution methods. Mean estimates of size-resolved penetration factors ranged from 0.41 ± 0.14 to 0.73 ± 0.05 across the range of measured particle sizes, while mean estimates of penetration factors for integral measures of UFPs and PM 2.5 were 0.67 ± 0.05 and 0.73 ± 0.05, respectively. Average relative uncertainties for all particle sizes/classes were less than 20%. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Effect of particle size on enzymatic hydrolysis of pretreated Miscanthus

    USDA-ARS?s Scientific Manuscript database

    Particle size reduction is a crucial factor in transportation logistics as well as cellulosic conversion. The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was determined. Miscanthus was ground using a hammer mill equipped with screens having 0.08, 2.0 or 6.0...

  10. Light absorption by coated nano-sized carbonaceous particles

    NASA Astrophysics Data System (ADS)

    Gangl, Martin; Kocifaj, Miroslav; Videen, Gorden; Horvath, Helmuth

    The optical properties of strongly absorbing soot particles coated by transparent material are investigated experimentally and described by several modeling approaches. Soot is produced by spark discharge and passed through a Sinclair-La Mer generator where non-absorbing carnauba wax is condensed onto it to obtain internal soot-wax mixtures in a controlled way. Measurements of the extinction and volume scattering coefficient show an amplification of absorption by a factor of approximately 1.8. This behavior was described by different approaches of internally mixed materials for the modal diameters of the measured size distributions: concentric-sphere model, effective medium approximations and heterogeneous ellipsoids. The concentric-sphere model describes the absorption increase quantitatively; and hence, it is chosen to be applied to the entire particle population in the size distribution. The growth of the soot particles by condensing wax is described by a simplified growth model to estimate the different contributions of several soot particle diameters to the overall absorption cross-section.

  11. Light scattering by lunar-like particle size distributions

    NASA Technical Reports Server (NTRS)

    Goguen, Jay D.

    1991-01-01

    A fundamental input to models of light scattering from planetary regoliths is the mean phase function of the regolith particles. Using the known size distribution for typical lunar soils, the mean phase function and mean linear polarization for a regolith volume element of spherical particles of any composition were calculated from Mie theory. The two contour plots given here summarize the changes in the mean phase function and linear polarization with changes in the real part of the complex index of refraction, n - ik, for k equals 0.01, the visible wavelength 0.55 micrometers, and the particle size distribution of the typical mature lunar soil 72141. A second figure is a similar index-phase surface, except with k equals 0.1. The index-phase surfaces from this survey are a first order description of scattering by lunar-like regoliths of spherical particles of arbitrary composition. They form the basis of functions that span a large range of parameter-space.

  12. Photometric imaging in particle size measurement and surface visualization.

    PubMed

    Sandler, Niklas

    2011-09-30

    The aim of this paper is to give an insight into photometric particle sizing approaches, which differ from the typical particle size measurement of dispersed particles. These approaches can often be advantageous especially for samples that are moist or cohesive, when dispersion of particles is difficult or sometimes impossible. The main focus of this paper is in the use of photometric stereo imaging. The technique allows the reconstruction of three-dimensional images of objects using multiple light sources in illumination. The use of photometric techniques is demonstrated in at-line measurement of granules and on-line measurement during granulation and dry milling. Also, surface visualization and roughness measurements are briefly discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. Particle size distributions in chondritic meteorites: Evidence for pre-planetesimal histories

    NASA Astrophysics Data System (ADS)

    Simon, J. I.; Cuzzi, J. N.; McCain, K. A.; Cato, M. J.; Christoffersen, P. A.; Fisher, K. R.; Srinivasan, P.; Tait, A. W.; Olson, D. M.; Scargle, J. D.

    2018-07-01

    Magnesium-rich silicate chondrules and calcium-, aluminum-rich refractory inclusions (CAIs) are fundamental components of primitive chondritic meteorites. It has been suggested that concentration of these early-formed particles by nebular sorting processes may lead to accretion of planetesimals, the planetary bodies that represent the building blocks of the terrestrial planets. In this case, the size distributions of the particles may constrain the accretion process. Here we present new particle size distribution data for Northwest Africa 5717, a primitive ordinary chondrite (ungrouped 3.05) and the well-known carbonaceous chondrite Allende (CV3). Instead of the relatively narrow size distributions obtained in previous studies (Ebel et al., 2016; Friedrich et al., 2015; Paque and Cuzzi, 1997, and references therein), we observed broad size distributions for all particle types in both meteorites. Detailed microscopic image analysis of Allende shows differences in the size distributions of chondrule subtypes, but collectively these subpopulations comprise a composite "chondrule" size distribution that is similar to the broad size distribution found for CAIs. Also, we find accretionary 'dust' rims on only a subset (∼15-20%) of the chondrules contained in Allende, which indicates that subpopulations of chondrules experienced distinct histories prior to planetary accretion. For the rimmed subset, we find positive correlation between rim thickness and chondrule size. The remarkable similarity between the size distributions of various subgroups of particles, both with and without fine grained rims, implies a common size sorting process. Chondrite classification schemes, astrophysical disk models that predict a narrow chondrule size population and/or a common localized formation event, and conventional particle analysis methods must all be critically reevaluated. We support the idea that distinct "lithologies" in NWA 5717 are nebular aggregates of chondrules. If ≥cm-sized

  14. Particle Size Distributions in Chondritic Meteorites: Evidence for Pre-Planetesimal Histories

    NASA Technical Reports Server (NTRS)

    Simon, J. I.; Cuzzi, J. N.; McCain, K. A.; Cato, M. J.; Christoffersen, P. A.; Fisher, K. R.; Srinivasan, P.; Tait, A. W.; Olson, D. M.; Scargle, J. D.

    2018-01-01

    Magnesium-rich silicate chondrules and calcium-, aluminum-rich refractory inclusions (CAIs) are fundamental components of primitive chondritic meteorites. It has been suggested that concentration of these early-formed particles by nebular sorting processes may lead to accretion of planetesimals, the planetary bodies that represent the building blocks of the terrestrial planets. In this case, the size distributions of the particles may constrain the accretion process. Here we present new particle size distribution data for Northwest Africa 5717, a primitive ordinary chondrite (ungrouped 3.05) and the well-known carbonaceous chondrite Allende (CV3). Instead of the relatively narrow size distributions obtained in previous studies (Ebel et al., 2016; Friedrich et al., 2015; Paque and Cuzzi, 1997, and references therein), we observed broad size distributions for all particle types in both meteorites. Detailed microscopic image analysis of Allende shows differences in the size distributions of chondrule subtypes, but collectively these subpopulations comprise a composite "chondrule" size distribution that is similar to the broad size distribution found for CAIs. Also, we find accretionary 'dust' rims on only a subset (approximately 15-20 percent) of the chondrules contained in Allende, which indicates that subpopulations of chondrules experienced distinct histories prior to planetary accretion. For the rimmed subset, we find positive correlation between rim thickness and chondrule size. The remarkable similarity between the size distributions of various subgroups of particles, both with and without fine grained rims, implies a common size sorting process. Chondrite classification schemes, astrophysical disk models that predict a narrow chondrule size population and/or a common localized formation event, and conventional particle analysis methods must all be critically reevaluated. We support the idea that distinct "lithologies" in NWA 5717 are nebular aggregates of

  15. Size, shape and flow characterization of ground wood chip and ground wood pellet particles

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

    Rezaei, Hamid; Lim, C. Jim; Lau, Anthony

    Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

  16. Size, shape and flow characterization of ground wood chip and ground wood pellet particles

    DOE PAGES

    Rezaei, Hamid; Lim, C. Jim; Lau, Anthony; ...

    2016-07-11

    Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

  17. Effect of four different size reduction methods on the particle size, solubility enhancement and physical stability of nicergoline nanocrystals.

    PubMed

    Martena, Valentina; Shegokar, Ranjita; Di Martino, Piera; Müller, Rainer H

    2014-09-01

    Nicergoline, a poorly soluble active pharmaceutical ingredient, possesses vaso-active properties which causes peripheral and central vasodilatation. In this study, nanocrystals of nicergoline were prepared in an aqueous solution of polysorbate 80 (nanosuspension) by using four different laboratory scale size reduction techniques: high pressure homogenization (HPH), bead milling (BM) and combination techniques (high pressure homogenization followed by bead milling HPH + BM, and bead milling followed by high pressure homogenization BM + HPH). Nanocrystals were investigated regarding to their mean particles size, zeta potential and particle dissolution. A short term physical stability study on nanocrystals stored at three different temperatures (4, 20 and 40 °C) was performed to evaluate the tendency to change in particle size, aggregation and zeta potential. The size reduction technique and the process parameters like milling time, number of homogenization cycles and pressure greatly affected the size of nanocrystals. Among the techniques used, the combination techniques showed superior and consistent particle size reduction compared to the other two methods, HPH + BM and BM + HPH giving nanocrystals of a mean particle size of 260 and 353 nm, respectively. The particle dissolution was increased for any nanocrystals samples, but it was particularly increased by HPH and combination techniques. Independently to the production method, nicergoline nanocrystals showed slight increase in particle size over the time, but remained below 500 nm at 20 °C and refrigeration conditions.

  18. Biosafety of the application of biogenic nanometal powders in husbandry

    NASA Astrophysics Data System (ADS)

    Anatolievna Nazarova, Anna; Dmitrievna Polischuk, Svetlana; Anatolievna Stepanova, Irina; Ivanovich Churilov, Gennady; Chau Nguyen, Hoai; Buu Ngo, Quoc

    2014-03-01

    Effects of iron and copper nanopowders (particle size of 20-40 nm) were investigated on rabbits of 1 month age and heifers of 6 months. For introduction of nanometals into the animal's ration, the mixed fodder was treated with the nanometal powder suspension in such a way: 0.08 mg of nanoiron per kg of animal's body weight and 0.04 mg kg-1 for nanocopper. The weight gain of the heifers who received nanoiron and nanocopper after 8 months was 22.4 and 10.7% higher than that of the control, respectively. For the rabbits who received nano Fe and Cu after 3 months, the weight gain was 11.7 and 7.3% compared to the control, respectively. Under the action of metal nanopowders morphological indices of blood were changed in comparison with the control: after 8 months the quantity of erythrocytes increased by 19.6%, hemoglobin by 17.1% and leukocytes by 7.6%. There was a realignment in leukocytic formula: the quantity of lymphocytes increased by 9% compared to the control. Biogenic metals in superdispersive state were able to stimulate immune, enzymatic and humoral systems of the animal's organism, promoting metabolism. Adding Co and Cu metal nanopowders to the bull-calves’ fodder rations increased content of Ca by 31.8 and 0%, Fe by 38.8 and 37.5%, K by 19.2 and 15.3%, Mg by 17.6 and 23.5%, Mn by 9.8 and 45% and Na by 20.5 and 8.8%, respectively, compared to control. Metal nanopowders improved the quality indices and meat productivity of black-white bull-calves, expressed in intensive growth of muscle, tissue and more nutritious meat. The conducted veterinary-sanitary expertise showed that the supplements based on iron, cobalt and copper nanopowders can be used as safe bioactive supplements in animal husbandry.

  19. Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles.

    PubMed

    Dahlman-Höglund, Anna; Lindgren, Åsa; Mattsby-Baltzer, Inger

    2016-08-01

    Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems. © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  20. Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells.

    PubMed

    Faklaris, Orestis; Joshi, Vandana; Irinopoulou, Theano; Tauc, Patrick; Sennour, Mohamed; Girard, Hugues; Gesset, Céline; Arnault, Jean-Charles; Thorel, Alain; Boudou, Jean-Paul; Curmi, Patrick A; Treussart, François

    2009-12-22

    Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm), resonant laser scattering and Raman scattering cross sections are too small to allow single nanoparticle observation. Nanodiamonds can, however, be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time scales. In this work, we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells. By blocking selectively different uptake processes, we show that nanodiamonds enter cells mainly by endocytosis, and converging data indicate that it is clathrin-mediated. We also examine nanodiamond intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule delivery.

  1. Physical and Tribological Characteristics of Ion-Implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Heidger, S.; Korenyi-Both, A. L.; Jayne, D. T.; Herrera-Fierro, P.; Shogrin, B.; Wilbur, P. J.; Wu, R. L. C.; Garscadden, A.; Barnes, P. N.

    1994-01-01

    Unidirectional sliding friction experiments were conducted with a natural, polished diamond pin in contact with both as-deposited and carbon-ion-implanted diamond films in ultrahigh vacuum. Diamond films were deposited on silicon, silicon carbide, and silicon nitride by microwave-plasma-assisted chemical vapor deposition. The as-deposited diamond films were impacted with carbon ions at an accelerating energy of 60 keV and a current density of 50 micron A/cm(exp 2) for approximately 6 min, resulting in a dose of 1.2 x 10(exp 17) carbon ions/cm(exp 2). The results indicate that the carbon ion implantation produced a thin surface layer of amorphous, nondiamond carbon. The nondiamond carbon greatly decreased both friction and wear of the diamond films. The coefficients of friction for the carbon-ion-implanted, fine-grain diamond films were less than 0.1, factors of 20 to 30 lower than those for the as-deposited, fine-grain diamond films. The coefficients of friction for the carbon-ion-implanted, coarse-grain diamond films were approximately 0.35, a factor of five lower than those for the as-deposited, coarse-grain diamond films. The wear rates for the carbon-ion-implanted, diamond films were on the order of 10(exp -6) mm(exp 3)/Nm, factors of 30 to 80 lower than that for the as-deposited diamond films, regardless of grain size. The friction of the carbon-ion-implanted diamond films was greatly reduced because the amorphous, nondiamond carbon, which had a low shear strength, was restricted to the surface layers (less than 0.1 micron thick) and because the underlying diamond materials retained their high hardness. In conclusion, the carbon-ion-implanted, fine-grain diamond films can be used effectively as wear resistant, self-lubricating coatings for ceramics, such as silicon nitride and silicon carbide, in ultrahigh vacuum.

  2. Inhibiting the oxidation of diamond during preparing the vitrified dental grinding tools by depositing a ZnO coating using direct urea precipitation method.

    PubMed

    Wang, Yanhui; Yuan, Yungang; Cheng, Xiaozhe; Li, Xiaohu; Zang, Jianbing; Lu, Jing; Yu, Yiqing; Xu, Xipeng

    2015-08-01

    Oxidation of diamond during the manufacturing of vitrified dental grinding tools would reduce the strength and sharpness of tools. Zinc oxide (ZnO) coating was deposited on diamond particles by urea precipitation method to protect diamond in borosilicate glass. The FESEM results showed that the ZnO coating was formed by plate-shaped particles. According to the TG results, the onset oxidation temperature of the ZnO-coated diamond was about 70 °C higher than the pristine diamond. The EDS results showed that ZnO diffused into the borosilicate glass during sintering. As the result, the bending strength of the composites containing ZnO-coated diamond was increased by 24% compared to that of the composites containing pristine diamond. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Performance of a Nanometer Resolution BPM System

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

    Walston, S.; Chung, C.; Fitsos, P.

    2007-04-24

    International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Acceleratormore » Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on variable-length struts which allow movement in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a calibration algorithm which is immune to beam jitter. To date, we have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of +/- 20 microns. We report on the progress of these ongoing tests.« less

  4. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. A review of the state of the global industrial diamond industry in 1999 is presented. World consumption of industrial diamond has increased annually in recent years, with an estimated 500 million carats valued between $650 million and $800 million consumed in 1999. In 1999, the U.S. was the world's largest market for industrial diamond and was also one of the world's main producers; the others were Ireland, Russia, and South Africa. Uses of industrial diamonds are discussed, and prices of natural and synthetic industrial diamond are reported.

  5. Nanometer-sized alumina packed microcolumn solid-phase extraction combined with field-amplified sample stacking-capillary electrophoresis for the speciation analysis of inorganic selenium in environmental water samples.

    PubMed

    Duan, Jiankuan; Hu, Bin; He, Man

    2012-10-01

    In this paper, a new method of nanometer-sized alumina packed microcolumn SPE combined with field-amplified sample stacking (FASS)-CE-UV detection was developed for the speciation analysis of inorganic selenium in environmental water samples. Self-synthesized nanometer-sized alumina was packed in a microcolumn as the SPE adsorbent to retain Se(IV) and Se(VI) simultaneously at pH 6 and the retained inorganic selenium was eluted by concentrated ammonia. The eluent was used for FASS-CE-UV analysis after NH₃ evaporation. The factors affecting the preconcentration of both Se(IV) and Se(VI) by SPE and FASS were studied and the optimal CE separation conditions for Se(IV) and Se(VI) were obtained. Under the optimal conditions, the LODs of 57 ng L⁻¹ (Se(IV)) and 71 ng L⁻¹ (Se(VI)) were obtained, respectively. The developed method was validated by the analysis of a certified reference material of GBW(E)080395 environmental water and the determined value was in a good agreement with the certified value. It was also successfully applied to the speciation analysis of inorganic selenium in environmental water samples, including Yangtze River water, spring water, and tap water. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Dealing with non-unique and non-monotonic response in particle sizing instruments

    NASA Astrophysics Data System (ADS)

    Rosenberg, Phil

    2017-04-01

    A number of instruments used as de-facto standards for measuring particle size distributions are actually incapable of uniquely determining the size of an individual particle. This is due to non-unique or non-monotonic response functions. Optical particle counters have non monotonic response due to oscillations in the Mie response curves, especially for large aerosol and small cloud droplets. Scanning mobility particle sizers respond identically to two particles where the ratio of particle size to particle charge is approximately the same. Images of two differently sized cloud or precipitation particles taken by an optical array probe can have similar dimensions or shadowed area depending upon where they are in the imaging plane. A number of methods exist to deal with these issues, including assuming that positive and negative errors cancel, smoothing response curves, integrating regions in measurement space before conversion to size space and matrix inversion. Matrix inversion (also called kernel inversion) has the advantage that it determines the size distribution which best matches the observations, given specific information about the instrument (a matrix which specifies the probability that a particle of a given size will be measured in a given instrument size bin). In this way it maximises use of the information in the measurements. However this technique can be confused by poor counting statistics which can cause erroneous results and negative concentrations. Also an effective method for propagating uncertainties is yet to be published or routinely implemented. Her we present a new alternative which overcomes these issues. We use Bayesian methods to determine the probability that a given size distribution is correct given a set of instrument data and then we use Markov Chain Monte Carlo methods to sample this many dimensional probability distribution function to determine the expectation and (co)variances - hence providing a best guess and an uncertainty for

  7. Designer Diamonds: Applications in Iron-based Superconductors and Lanthanides

    NASA Astrophysics Data System (ADS)

    Vohra, Yogesh

    2013-06-01

    This talk will focus on the recent progress in the fabrication of designer diamond anvils as well as scientific applications of these diamonds in static high pressure research. The two critical parameters that have emerged in the microwave plasma chemical vapor deposition of designer diamond anvils are (1) the precise [100] alignment of the starting diamond substrate and (2) balancing the competing roles of parts per million levels of nitrogen and oxygen in the diamond growth plasma. The control of these parameters results in the fabrication of high quality designer diamonds with culet size in excess of 300 microns in diameter. The three different applications of designer diamond anvils will be discussed (1) simultaneous electrical resistance and crystal structure measurements using a synchrotron source on Iron-based superconductors with data on both electron and hole doped BaFe2As2 materials and other novel superconducting materials (2) high-pressure high-temperature melting studies on metals using eight-probe Ohmic heating designer diamonds and (3) high pressure low temperature studies on magnetic behavior of 4f-lanthanide metals using four-probe electrical resistance measurements and complementary neutron diffraction studies on a spallation neutron source. Future opportunities in boron-doped conducting designer diamond anvils as well as fabrication of two-stage designer diamonds for ultra high pressure experiments will also be presented. This work was supported by the Department of Energy (DOE) - National Nuclear Security Administration (NNSA) under Grant No. DE-FG52-10NA29660.

  8. Particle mobility size spectrometers: harmonization of technical standards and data structure to facilitate high quality long-term observations of atmospheric particle number size distributions

    NASA Astrophysics Data System (ADS)

    Wiedensohler, A.; Birmili, W.; Nowak, A.; Sonntag, A.; Weinhold, K.; Merkel, M.; Wehner, B.; Tuch, T.; Pfeifer, S.; Fiebig, M.; Fjäraa, A. M.; Asmi, E.; Sellegri, K.; Depuy, R.; Venzac, H.; Villani, P.; Laj, P.; Aalto, P.; Ogren, J. A.; Swietlicki, E.; Roldin, P.; Williams, P.; Quincey, P.; Hüglin, C.; Fierz-Schmidhauser, R.; Gysel, M.; Weingartner, E.; Riccobono, F.; Santos, S.; Grüning, C.; Faloon, K.; Beddows, D.; Harrison, R. M.; Monahan, C.; Jennings, S. G.; O'Dowd, C. D.; Marinoni, A.; Horn, H.-G.; Keck, L.; Jiang, J.; Scheckman, J.; McMurry, P. H.; Deng, Z.; Zhao, C. S.; Moerman, M.; Henzing, B.; de Leeuw, G.

    2010-12-01

    Particle mobility size spectrometers often referred to as DMPS (Differential Mobility Particle Sizers) or SMPS (Scanning Mobility Particle Sizers) have found a wide application in atmospheric aerosol research. However, comparability of measurements conducted world-wide is hampered by lack of generally accepted technical standards with respect to the instrumental set-up, measurement mode, data evaluation as well as quality control. This article results from several instrument intercomparison workshops conducted within the European infrastructure project EUSAAR (European Supersites for Atmospheric Aerosol Research). Under controlled laboratory conditions, the number size distribution from 20 to 200 nm determined by mobility size spectrometers of different design are within an uncertainty range of ±10% after correcting internal particle losses, while below and above this size range the discrepancies increased. Instruments with identical design agreed within ±3% in the peak number concentration when all settings were done carefully. Technical standards were developed for a minimum requirement of mobility size spectrometry for atmospheric aerosol measurements. Technical recommendations are given for atmospheric measurements including continuous monitoring of flow rates, temperature, pressure, and relative humidity for the sheath and sample air in the differential mobility analyser. In cooperation with EMEP (European Monitoring and Evaluation Program), a new uniform data structure was introduced for saving and disseminating the data within EMEP. This structure contains three levels: raw data, processed data, and final particle size distributions. Importantly, we recommend reporting raw measurements including all relevant instrument parameters as well as a complete documentation on all data transformation and correction steps. These technical and data structure standards aim to enhance the quality of long-term size distribution measurements, their comparability between

  9. How do dairy cows chew?--particle size analysis of selected feeds with different particle length distributions and of respective ingested bolus particles.

    PubMed

    Schadt, I; Ferguson, J D; Azzaro, G; Petriglieri, R; Caccamo, M; Van Soest, P; Licitra, G

    2012-08-01

    Not only feed but also respective bolus particle size could alter diet efficiency and cow performance. The objective of this project was to characterize particle size of selected feeds and respective swallowed boli. Feed samples included 6 different particle length rye grass hay samples, 1 grass silage, 1 corn silage, and 1 total mixed ration (TMR). Rye grass hay samples consisted of long hay and chopped hay particles retained on the 19- (19_PSPS hay), 8- (8_PSPS hay), and 1.18-mm (1.18_PSPS hay) Penn State Particle Separator (PSPS) screens and those collected on the pan (PSPS_pan hay). A sixth hay treatment was rye grass forage cut at 50-mm lengths and dried to hay (50-mm hay). Treatments were offered to 4 nonlactating and 4 lactating cows following rumen evacuation. Swallowed boli were collected and the number of chews per gram of ingested feed dry matter was determined. Feed and bolus particles of lengths ≥5mm were collected on a 1.6-mm screen using a horizontal wet sieving technique. This cut point was chosen, as the literature suggests that most fecal particles are shorter than 5mm. Dry matter proportions on this screen (PROP_1.6) were determined and particle lengths of retained particles were measured by image analysis. Mean particle lengths (ML) were calculated considering particles ≥5mm in length. Boli of long hay, of 19_PSPS hay, of 8_PSPS hay, and of 50-mm hay had similar ML of 10 to 11mm. Bolus PROP_1.6 were also similar between these treatments, ranging from 0.54 to 0.69. Bolus particle lengths and distributions of these treatments were not related to respective hay particles. Bolus of 1.18_PSPS hay had PROP_1.6 of 0.51 and a smaller ML of 8mm. The PSPS_pan hay had PROP_1.6 of only 0.33, but was still chewed intensely. Apparently, little particle size reduction occurred when cows ate the TMR or the silages. Feed and respective bolus PROP_1.6 were as follows: 0.66 and 0.59 in grass silage, 0.52 and 0.55 in corn silage, and 0.44 and 0.38 in the TMR

  10. Determining suspended sediment particle size information from acoustical and optical backscatter measurements

    NASA Astrophysics Data System (ADS)

    Lynch, James F.; Irish, James D.; Sherwood, Christopher R.; Agrawal, Yogesh C.

    1994-08-01

    During the winter of 1990-1991 an Acoustic BackScatter System (ABSS), five Optical Backscatterance Sensors (OBSs) and a Laser In Situ Settling Tube (LISST) were deployed in 90 m of water off the California coast for 3 months as part of the Sediment Transport Events on Shelves and Slopes (STRESS) experiment. By looking at sediment transport events with both optical (OBS) and acoustic (ABSS) sensors, one obtains information about the size of the particles transported as well as their concentration. Specifically, we employ two different methods of estimating "average particle size". First, we use vertical scattering intensity profile slopes (acoustical and optical) to infer average particle size using a Rouse profile model of the boundary layer and a Stokes law fall velocity assumption. Secondly, we use a combination of optics and acoustics to form a multifrequency (two frequency) inverse for the average particle size. These results are compared to independent observations from the LISST instrument, which measures the particle size spectrum in situ using laser diffraction techniques. Rouse profile based inversions for particle size are found to be in good agreement with the LISST results except during periods of transport event initiation, when the Rouse profile is not expected to be valid. The two frequency inverse, which is boundary layer model independent, worked reasonably during all periods, with average particle sizes correlating well with the LISST estimates. In order to further corroborate the particle size inverses from the acoustical and optical instruments, we also examined size spectra obtained from in situ sediment grab samples and water column samples (suspended sediments), as well as laboratory tank experiments using STRESS sediments. Again, good agreement is noted. The laboratory tank experiment also allowed us to study the acoustical and optical scattering law characteristics of the STRESS sediments. It is seen that, for optics, using the cross

  11. Episodic diamond growth beneath the Kaapvaal Craton at Jwaneng Mine, Botswana

    NASA Astrophysics Data System (ADS)

    Gress, Michael U.; Howell, Daniel; Chinn, Ingrid L.; Speich, Laura; Kohn, Simon C.; van den Heuvel, Quint; Schulten, Ellen; Pals, Anna S. M.; Davies, Gareth R.

    2018-05-01

    Important implications for the interior workings of the Earth can be drawn by studying diamonds and their inclusions. To better understand the timing and number of diamond forming events beneath the NW margin of the Kaapvaal Craton, a comprehensive reassessment of Jwaneng's diamond populations has been undertaken. We report new inclusion abundance data from the visual examination of 130,000 diamonds that validate the predominance of an eclogitic diamond suite (up to 88%) with on average 5% inclusion-bearing diamonds (with inclusions >10 μm in size). From this population, polished plates from 79 diamonds of eclogitic and peridotitic paragenesis have been studied with cathodoluminescence (CL) imaging and infrared spectroscopy (FTIR) traverses. The majority (80%) record major changes in N concentration and aggregation states, as well as sharp boundaries in the CL images of individual plates that are interpreted to demarcate discrete diamond growth events. In addition, bulk FTIR data have been acquired for 373 unpolished diamonds. Silicate inclusions sampled from distinct growth zones define 2 compositional groups of omphacites and pyrope-almandines associated with different N contents in their diamond hosts. These findings reinforce previous observations that at Jwaneng at least seven individual diamond forming events can be identified - 3 peridotitic and 4 eclogitic. The results demonstrate that detailed examination of diamond plates by CL imaging and FTIR traverses is necessary to unveil the complex history recorded in diamonds.

  12. Realization of deep 3D metal electrodes in diamond radiation detectors

    NASA Astrophysics Data System (ADS)

    Wulz, Thomas; Gerding, William; Lavrik, Nickolay; Briggs, Dayrl; Srijanto, Bernadeta; Lester, Kevin; Hensley, Dale; Spanier, Stefan; Lukosi, Eric

    2018-05-01

    A fabrication technique to create 3D diamond detectors is presented. Deep reactive ion etching was used to create an array of through-diamond vias (TDVs) in a 2 × 2 × 0.15 mm3 electronic grade single crystal diamond detector. The diameter of the TDVs was nominally 30 μm with a pitch of 100 μm between them. The TDVs were filled with chromium using hexavalent chromium electroplating to create 3D electrodes, which were connected electrically by interdigitated electrodes. The fabricated 3D diamond detector responded to both alpha particles and X-rays, exhibiting a charge collection efficiency of 52.3% at 200 V. Comparing to a diamond detector with the same interdigitated electrodes, but no 3D electrodes, confirms that the 3D electrodes are electrically active within the device. The average resistivity of the 3D electrodes is 2.89 ± 0.03 × 10-5 Ω cm, near that of bulk chromium. These results indicate that this fabrication technique is a potential option for 3D diamond detector fabrication.

  13. "Size-Independent" Single-Electron Tunneling.

    PubMed

    Zhao, Jianli; Sun, Shasha; Swartz, Logan; Riechers, Shawn; Hu, Peiguang; Chen, Shaowei; Zheng, Jie; Liu, Gang-Yu

    2015-12-17

    Incorporating single-electron tunneling (SET) of metallic nanoparticles (NPs) into modern electronic devices offers great promise to enable new properties; however, it is technically very challenging due to the necessity to integrate ultrasmall (<10 nm) particles into the devices. The nanosize requirements are intrinsic for NPs to exhibit quantum or SET behaviors, for example, 10 nm or smaller, at room temperature. This work represents the first observation of SET that defies the well-known size restriction. Using polycrystalline Au NPs synthesized via our newly developed solid-state glycine matrices method, a Coulomb Blockade was observed for particles as large as tens of nanometers, and the blockade voltage exhibited little dependence on the size of the NPs. These observations are counterintuitive at first glance. Further investigations reveal that each observed SET arises from the ultrasmall single crystalline grain(s) within the polycrystal NP, which is (are) sufficiently isolated from the nearest neighbor grains. This work demonstrates the concept and feasibility to overcome orthodox spatial confinement requirements to achieve quantum effects.

  14. Effect of Particle Size and Impact Velocity on Collision Behaviors Between Nano-Scale TiN Particles: MD Simulation.

    PubMed

    Yao, Hai-Long; Hu, Xiao-Zhen; Yang, Guan-Jun

    2018-06-01

    Inter-particle bonding formation which determines qualities of nano-scale ceramic coatings is influenced by particle collision behaviors during high velocity collision processes. In this study, collision behaviors between nano-scale TiN particles with different diameters were illuminated by using Molecular Dynamics simulation through controlling impact velocities. Results show that nano-scale TiN particles exhibit three states depending on particle sizes and impact velocities, i.e., bonding, bonding with localized fracturing, and rebounding. These TiN particles states are summarized into a parameter selection map providing an overview of the conditions in terms of particle sizes and velocities. Microstructure results show that localized atoms displacement and partial fracture around the impact region are main reasons for bonding formation of nano-scale ceramic particles, which shows differences from conventional particles refining and amorphization. A relationship between the adhesion energy and the rebound energy is established to understand bonding formation mechanism for nano-scale TiN particle collision. Results show that the energy relationship is depended on the particle sizes and impact velocities, and nano-scale ceramic particles can be bonded together as the adhesion energy being higher than the rebound energy.

  15. Laser Doppler spectrometer method of particle sizing. [for air pollution

    NASA Technical Reports Server (NTRS)

    Weber, F. N.

    1976-01-01

    A spectrometer for the detection of airborne particulate pollution in the submicron size range is described. In this device, airborne particles are accelerated through a supersonic nozzle, with different sizes achieving different velocities in the gas flow. Information about the velocities of the accelerated particles is obtained with a laser-heterodyne optical system through the Doppler shift of light scattered from the particles. Detection is accomplished by means of a photomultiplier. Nozzle design and signal processing techniques are also discussed.

  16. Experimental Effects on IR Reflectance Spectra: Particle Size and Morphology

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

    Beiswenger, Toya N.; Myers, Tanya L.; Brauer, Carolyn S.

    For geologic and extraterrestrial samples it is known that both particle size and morphology can have strong effects on the species’ infrared reflectance spectra. Due to such effects, the reflectance spectra cannot be predicted from the absorption coefficients alone. This is because reflectance is both a surface as well as a bulk phenomenon, incorporating both dispersion as well as absorption effects. The same spectral features can even be observed as either a maximum or minimum. The complex effects depend on particle size and preparation, as well as the relative amplitudes of the optical constants n and k, i.e. the realmore » and imaginary components of the complex refractive index. While somewhat oversimplified, upward-going amplitude in the reflectance spectrum usually result from surface scattering, i.e. rays that have been reflected from the surface without penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. While the effects are well known, we report seminal measurements of reflectance along with quantified particle size of the samples, the sizing obtained from optical microscopy measurements. The size measurements are correlated with the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to understand the effects on the spectral features as a function of the mean grain size of the sample. We report results for both sodium sulfate Na2SO4 as well as ammonium sulfate (NH4)2SO4; the optical constants have been measured for (NH4)2SO4. To go a step further from the field to the laboratory we explore our understanding of particle size effects on reflectance spectra in the field using standoff detection. This has helped identify weaknesses and strengths in detection using standoff distances of up 160 meters away from the Target. The

  17. Online submicron particle sizing by dynamic light scattering using autodilution

    NASA Technical Reports Server (NTRS)

    Nicoli, David F.; Elings, V. B.

    1989-01-01

    Efficient production of a wide range of commercial products based on submicron colloidal dispersions would benefit from instrumentation for online particle sizing, permitting real time monitoring and control of the particle size distribution. Recent advances in the technology of dynamic light scattering (DLS), especially improvements in algorithms for inversion of the intensity autocorrelation function, have made it ideally suited to the measurement of simple particle size distributions in the difficult submicron region. Crucial to the success of an online DSL based instrument is a simple mechanism for automatically sampling and diluting the starting concentrated sample suspension, yielding a final concentration which is optimal for the light scattering measurement. A proprietary method and apparatus was developed for performing this function, designed to be used with a DLS based particle sizing instrument. A PC/AT computer is used as a smart controller for the valves in the sampler diluter, as well as an input-output communicator, video display and data storage device. Quantitative results are presented for a latex suspension and an oil-in-water emulsion.

  18. Precision diamond grinding of ceramics and glass

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

    Smith, S.; Paul, H.; Scattergood, R.O.

    A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughnessmore » value`s can be much less than the long-crack toughness values measured in conventional fracture tests.« less

  19. Size exclusion chromatography with superficially porous particles.

    PubMed

    Schure, Mark R; Moran, Robert E

    2017-01-13

    A comparison is made using size-exclusion chromatography (SEC) of synthetic polymers between fully porous particles (FPPs) and superficially porous particles (SPPs) with similar particle diameters, pore sizes and equal flow rates. Polystyrene molecular weight standards with a mobile phase of tetrahydrofuran are utilized for all measurements conducted with standard HPLC equipment. Although it is traditionally thought that larger pore volume is thermodynamically advantageous in SEC for better separations, SPPs have kinetic advantages and these will be shown to compensate for the loss in pore volume compared to FPPs. The comparison metrics include the elution range (smaller with SPPs), the plate count (larger for SPPs), the rate production of theoretical plates (larger for SPPs) and the specific resolution (larger with FPPs). Advantages to using SPPs for SEC are discussed such that similar separations can be conducted faster using SPPs. SEC using SPPs offers similar peak capacities to that using FPPs but with faster operation. This also suggests that SEC conducted in the second dimension of a two-dimensional liquid chromatograph may benefit with reduced run time and with equivalently reduced peak width making SPPs advantageous for sampling the first dimension by the second dimension separator. Additional advantages are discussed for biomolecules along with a discussion of optimization criteria for size-based separations. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Generating Color from Polydisperse, Near Micron-Sized TiO2 Particles.

    PubMed

    Alam, Al-Mahmnur; Baek, Kyungnae; Son, Jieun; Pei, Yi-Rong; Kim, Dong Ha; Choy, Jin-Ho; Hyun, Jerome K

    2017-07-19

    Single particle Mie calculations of near micron-sized TiO 2 particles predict strong light scattering dominating the visible range that would give rise to a white appearance. We demonstrate that a polydisperse collection of these "white" particles can result in the generation of visible colors through ensemble scattering. The weighted averaging of the scattering over the particle size distribution modifies the sharp, multiple, high order scattering modes from individual particles into broad variations in the collective extinction. These extinction variations are apparent as visible colors for particles suspended in organic solvent at low concentration, or for a monolayer of particles supported on a transparent substrate viewed in front of a white light source. We further exploit the color variations on optical sensitivity to the surrounding environment to promote micron-sized TiO 2 particles as stable and robust agents for detecting the optical index of homogeneous media with high contrast sensitivities. Such distribution-modulated scattering properties provide TiO 2 particles an intriguing opportunity to impart color and optical sensitivity to their widespread electronic and chemical platforms such as antibacterial windows, catalysis, photocatalysis, optical sensors, and photovoltaics.

  1. A technique to measure the size of particles in laser Doppler velocimetry applications

    NASA Technical Reports Server (NTRS)

    Hess, C. F.

    1985-01-01

    A method to measure the size of particles in Laser Doppler Velocimeter (LDV) applications is discussed. Since in LDV the velocity of the flow is assocated with the velocity of particles to establish how well they follow the flow, in the present method the interferometric probe volume is surrounded by a larger beam of different polarization or wavelength. The particle size is then measured from the absolute intensity scattered from the large beam by particles crossing the fringes. Experiments using polystrene particles between 1.1 and 3.3 microns and larger glass beads are reported. It is shown that the method has an excellent size resolution and its accuracy is better than 10% for the particle size studied.

  2. Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)

    PubMed Central

    Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

    2010-01-01

    In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding. PMID:21617759

  3. LDL Particle Size and Reactive Oxygen Metabolites in Dyslipidemic Patients

    PubMed Central

    Kotani, Kazuhiko; Tsuzaki, Kokoro; Taniguchi, Nobuyuki; Sakane, Naoki

    2012-01-01

    Objectives: Small dense low-density lipoprotein (sdLDL) which has a small LDL particle size with greater susceptibility to oxidation is regarded as a risk marker for cardiovascular disease. The diacron reactive oxygen metabolites (d-ROMs) test has recently been introduced as an oxidative stress-related marker in the clinic. The aim of the present study was to investigate the correlation between the mean LDL particle size and the oxidative stress status as evaluated by the d-ROMs in dyslipidemic patients. Methods: The study included 278 dyslipidemic patients (121 male and 157 female, mean age, 60 years). Clinical data including the conventional atherosclerotic risk factors in addition to the mean LDL particle size measured with the gel electrophoresis and the d-ROMs were collected. Results: Male patients had a significantly smaller mean LDL particle size than females (262.2 ± 7.5 [SD] vs. 264.3 ± 6.7 Å, P<0.05), while female patients had a significantly higher d-ROMs level than males (318 ± 68 vs. 350 ± 72 U. Carr., P<0.01). A multiple regression analysis revealed that there was an independent, significant, and inverse correlation between the mean LDL particle size and the d-ROMs (β=−0.19, P<0.05). Conclusions: These findings of the co-existence of both markers suggest that sdLDL and oxidative stress can be cooperative in atherogenesis, possibly leading to the incidence of CVD, in dyslipidemic patients. PMID:22448308

  4. LDL Particle Size and Reactive Oxygen Metabolites in Dyslipidemic Patients.

    PubMed

    Kotani, Kazuhiko; Tsuzaki, Kokoro; Taniguchi, Nobuyuki; Sakane, Naoki

    2012-03-01

    Small dense low-density lipoprotein (sdLDL) which has a small LDL particle size with greater susceptibility to oxidation is regarded as a risk marker for cardiovascular disease. The diacron reactive oxygen metabolites (d-ROMs) test has recently been introduced as an oxidative stress-related marker in the clinic. The aim of the present study was to investigate the correlation between the mean LDL particle size and the oxidative stress status as evaluated by the d-ROMs in dyslipidemic patients. The study included 278 dyslipidemic patients (121 male and 157 female, mean age, 60 years). Clinical data including the conventional atherosclerotic risk factors in addition to the mean LDL particle size measured with the gel electrophoresis and the d-ROMs were collected. Male patients had a significantly smaller mean LDL particle size than females (262.2 ± 7.5 [SD] vs. 264.3 ± 6.7 Å, P<0.05), while female patients had a significantly higher d-ROMs level than males (318 ± 68 vs. 350 ± 72 U. Carr., P<0.01). A multiple regression analysis revealed that there was an independent, significant, and inverse correlation between the mean LDL particle size and the d-ROMs (β=-0.19, P<0.05). These findings of the co-existence of both markers suggest that sdLDL and oxidative stress can be cooperative in atherogenesis, possibly leading to the incidence of CVD, in dyslipidemic patients.

  5. Size-dependent microstructures in rapidly solidified uranium-niobium powder particles

    DOE PAGES

    McKeown, Joseph T.; Hsiung, Luke L.; Park, Jong M.; ...

    2016-06-14

    The microstructures of rapidly solidified U-6wt%Nb powder particles synthesized by centrifugal atomization were characterized using scanning electron microscopy and transmission electron microscopy. Observed variations in microstructure are related to particle sizes. All of the powder particles exhibited a two-zone microstructure. The formation of this two-zone microstructure is described by a transition from solidification controlled by internal heat flow and high solidification rate during recalescence (micro-segregation-free or partitionless growth) to solidification controlled by external heat flow with slower solidification rates (dendritic growth with solute redistribution). The extent of partitionless solidification increased with decreasing particle size due to larger undercoolings in smallermore » particles prior to solidification. The metastable phases that formed are related to variations in Nb concentration across the particles. Lastly, the microstructures of the powders were heavily twinned.« less

  6. Size-controlled synthesis, surface functionalization, and biological applications of thiol-organosilica particles.

    PubMed

    Nakamura, Michihiro; Ozaki, Shuji; Abe, Masahiro; Doi, Hiroyuki; Matsumoto, Toshio; Ishimura, Kazunori

    2010-08-01

    Thiol-organosilica particles of a narrow size distribution, made from 3-mercaptopropyltrimethoxysilane (MPMS), were prepared by means of a one-pot synthesis. We examined three synthetic conditions at high temperature (100 degrees C), including the Stöber synthesis and two entirely aqueous syntheses. Under all conditions, the sizes of MPMS particles were well controlled, and the average of the coefficient of variation for the size distribution was less than 20%. The incubation times required for formation of MPMS particles were shorter at high temperature than at low temperature. MPMS particles internally functionalized with fluorescent dye were also prepared by means of the same one-pot synthesis. On flow cytometry analysis these MPMS particles showed distinct peaks of scattering due to well-controlled sizes of particles as well as due to fluorescence signals. Real-time observation of interaction between fluorescent MPMPS particles and cultured cells could be observed under fluorescent microscopy with bright light. The surface of the as-prepared MPMS particles contained exposed mercaptopropyl residues, and the ability to adsorb proteins was at least 6 times higher than that of gold nanopaticles. In addition, fluorescein-labeled proteins adsorbed to the surface of the particles were quantitatively detected at the pg/ml level by flow cytometry. MPMS particles surface functionalized with anti-CD20 antibody using adsorption could bind with lymphoma cells expressing CD20 specifically. In this paper, we demonstrated the possibility of size-controlled thiol-organosilica particles for wild range of biological applications. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

  7. Simultaneous sizing and electrophoretic mobility measurement of sub-micron particles using Brownian motion

    PubMed Central

    Palanisami, Akilan; Miller, John H.

    2011-01-01

    The size and surface chemistry of micron scale particles are of fundamental importance in studies of biology and air particulate pollution. However, typical electrophoretic measurements of these and other sub-micron scale particles (300 nm – 1 μm) cannot resolve size information within heterogeneous mixtures unambiguously. Using optical microscopy, we monitor electrophoretic motion together with the Brownian velocity fluctuations—using the latter to measure size by either the Green-Kubo relation or by calibration from known size standards. Particle diameters are resolved to ±12% with 95% confidence. Strikingly, the size resolution improves as particle size decreases due to the increased Brownian motion. The sizing ability of the Brownian assessed electrophoresis method described here complements the electrophoretic mobility resolution of traditional capillary electrophoresis. PMID:20882556

  8. Particle size effects on viscosity of silver pastes: A manufacturer's view

    NASA Technical Reports Server (NTRS)

    Provance, J.; Allison, K.

    1983-01-01

    Particles from a variety of silver powders were investigated by scanning electron microscopy and particle size analyses. Particle size distribution curves and volume population graphs were prepared for these silver powders and for glass powders with optimum, extra fine and coarse particle sizes. The viscosity at a given shear rate and slope of viscosity over a range of shear rates were determined for thick film pastes made with these powders. Because of particle anomalies and variations, the need for flexibility to achieve the best printing qualities for silver pastes was evident. It was established that print quality, dried and fired film density and optimum contact of silver particles with silicon, important for cell electrical output, could be achieved by adjusting the slope of viscosity that fell outside of the range, -0.550 to -0.650. This was accomplished through organic vehicle technology that permitted a change in the slope of viscosity, up or down, while maintaining a constant silver and total solids content.

  9. The immersion freezing behavior of size-segregated soot and kaolinite particles

    NASA Astrophysics Data System (ADS)

    Hartmann, S.; Augustin, S.; Clauss, T.; Niedermeier, D.; Raddatz, M.; Wex, H.; Shaw, R. A.; Stratmann, F.

    2011-12-01

    Heterogeneous ice nucleation plays a crucial role for ice formation in mixed-phase and cirrus clouds and has an important impact on precipitation formation, global radiation balances, and therefore Earth's climate (Cantrell and Heymsfield, 2005). Mineral dust and soot particles are found to be a major component of ice crystal residues (e.g., Pratt et al., 2009) so these substances are potential sources of atmospheric ice nuclei (IN). Experimental studies investigating the immersion freezing behavior of size-segregated soot and kaolinite particles conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS) are presented. In our measurements only one aerosol particle is immersed in an air suspended water droplet which can trigger ice nucleation. The method facilitates very precise examinations with respect to temperature, ice nucleation time and ice nucleus size. Considering laboratory studies, the picture of the IN ability of soot particles is quite heterogeneous. Our studies show that submicron flame, spark soot particles and optionally coated with sulfuric acid to simulate chemically aging do not act as IN at temperatures higher than homogeneous freezing taking place. Therefore soot particles might not be an important source of IN for immersion freezing in the atmosphere. In contrast, kaolinite being representative for natural mineral dust with a well known composition and structure is found to be very active in forming ice for all freezing modes (e.g., Mason and Maybank, 1958). Analyzing the immersion freezing behavior of different sized kaolinite particles (300, 500 and 700 nm in diameter) the size effect was clearly observed, i.e. the ice fraction (number of frozen droplets per total number) scales with particle surface, i.e. the larger the ice nucleus surface the higher the ice fraction. The slope of the logarithm of the ice fraction as function of temperature is similar for all particle sizes investigated and fits very well with the results of L

  10. Lateral overgrowth of diamond film on stripes patterned Ir/HPHT-diamond substrate

    NASA Astrophysics Data System (ADS)

    Wang, Yan-Feng; Chang, Xiaohui; Liu, Zhangcheng; Liu, Zongchen; Fu, Jiao; Zhao, Dan; Shao, Guoqing; Wang, Juan; Zhang, Shaopeng; Liang, Yan; Zhu, Tianfei; Wang, Wei; Wang, Hong-Xing

    2018-05-01

    Epitaxial lateral overgrowth (ELO) of diamond films on patterned Ir/(0 0 1)HPHT-diamond substrates have been carried out by microwave plasma CVD system. Ir/(0 0 1)HPHT-diamond substrates are fabricated by photolithographic and magnetron sputtering technique. The morphology of the as grown ELO diamond film is characterized by optical microscopy and scanning electronic microscopy. The quality and stress of the ELO diamond film are investigated by surface etching pit density and micro-Raman spectroscopy. Two ultraviolet photodetectors are fabricated on ELO diamond area and non-ELO diamond area prepared on same substrate, and that one on ELO diamond area indicates better photoelectric properties. All results indicate quality of ELO diamond film is improved.

  11. Measurements and Diagnostics of Diamond Films and Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.

    1999-01-01

    The commercial potential of chemical-vapor-deposited (CVD) diamond films has been established and a number of applications have been identified through university, industry, and government research studies. This paper discusses the methodologies used for property measurement and diagnostic of CVD diamond films and coatings. Measurement and diagnostic techniques studied include scanning electron microscopy, transmission electron microscopy, atomic force microscopy, stylus profilometry, x-ray diffraction, electron diffraction, Raman spectroscopy, Rutherford backscattering, elastic recoil spectroscopy, and friction examination. Each measurement and diagnostic technique provides unique information. A combination of techniques can provide the technical information required to understand the quality and properties of CVD diamond films, which are important to their application in specific component systems and environments. In this study the combination of measurement and diagnostic techniques was successfully applied to correlate deposition parameters and resultant diamond film composition, crystallinity, grain size, surface roughness, and coefficient of friction.

  12. Characterization of particle number size distribution and new particle formation in Southern China.

    PubMed

    Huang, Xiaofeng; Wang, Chuan; Peng, Jianfei; He, Lingyan; Cao, Liming; Zhu, Qiao; Cui, Jie; Wu, Zhijun; Hu, Min

    2017-01-01

    Knowledge of particle number size distribution (PND) and new particle formation (NPF) events in Southern China is essential for mitigation strategies related to submicron particles and their effects on regional air quality, haze, and human health. In this study, seven field measurement campaigns were conducted from December 2013 to May 2015 using a scanning mobility particle sizer (SMPS) at four sites in Southern China, including three urban sites and one background site. Particles were measured in the size range of 15-615nm, and the median particle number concentrations (PNCs) were found to vary in the range of 0.3×10 4 -2.2×10 4 cm -3 at the urban sites and were approximately 0.2×10 4 cm -3 at the background site. The peak diameters at the different sites varied largely from 22 to 102nm. The PNCs in the Aitken mode (25-100nm) at the urban sites were up to 10 times higher than they were at the background site, indicating large primary emissions from traffic at the urban sites. The diurnal variations of PNCs were significantly influenced by both rush hour traffic at the urban sites and NPF events. The frequencies of NPF events at the different sites were 0%-30%, with the highest frequency occurring at an urban site during autumn. With higher SO 2 concentrations and higher ambient temperatures being necessary, NPF at the urban site was found to be more influenced by atmospheric oxidizing capability, while NPF at the background site was limited by the condensation sink. This study provides a unique dataset of particle number and size information in various environments in Southern China, which can help understand the sources, formation, and the climate forcing of aerosols in this quickly developing region, as well as help constrain and validate NPF modeling. Copyright © 2016. Published by Elsevier B.V.

  13. Biological evaluation of ultrananocrystalline and nanocrystalline diamond coatings.

    PubMed

    Skoog, Shelby A; Kumar, Girish; Zheng, Jiwen; Sumant, Anirudha V; Goering, Peter L; Narayan, Roger J

    2016-12-01

    Nanostructured biomaterials have been investigated for achieving desirable tissue-material interactions in medical implants. Ultrananocrystalline diamond (UNCD) and nanocrystalline diamond (NCD) coatings are the two most studied classes of synthetic diamond coatings; these materials are grown using chemical vapor deposition and are classified based on their nanostructure, grain size, and sp 3 content. UNCD and NCD are mechanically robust, chemically inert, biocompatible, and wear resistant, making them ideal implant coatings. UNCD and NCD have been recently investigated for ophthalmic, cardiovascular, dental, and orthopaedic device applications. The aim of this study was (a) to evaluate the in vitro biocompatibility of UNCD and NCD coatings and (b) to determine if variations in surface topography and sp 3 content affect cellular response. Diamond coatings with various nanoscale topographies (grain sizes 5-400 nm) were deposited on silicon substrates using microwave plasma chemical vapor deposition. Scanning electron microscopy and atomic force microscopy revealed uniform coatings with different scales of surface topography; Raman spectroscopy confirmed the presence of carbon bonding typical of diamond coatings. Cell viability, proliferation, and morphology responses of human bone marrow-derived mesenchymal stem cells (hBMSCs) to UNCD and NCD surfaces were evaluated. The hBMSCs on UNCD and NCD coatings exhibited similar cell viability, proliferation, and morphology as those on the control material, tissue culture polystyrene. No significant differences in cellular response were observed on UNCD and NCD coatings with different nanoscale topographies. Our data shows that both UNCD and NCD coatings demonstrate in vitro biocompatibility irrespective of surface topography.

  14. Industrial diamond

    USGS Publications Warehouse

    Olson, D.W.

    2011-01-01

    Estimated world production of natural and synthetic industrial diamond was about 4.44 billion carats in 2010. Natural industrial diamond deposits have been found in more than 35 countries, and synthetic industrial diamond is produced in at least 15 countries.

  15. Progress on glass ceramic ZERODUR enabling nanometer precision

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Weber, Peter; Westerhoff, Thomas

    2016-03-01

    The Semiconductor Industry is making continuous progress in shrinking feature size developing technologies and process to achieve < 10 nm feature size. The required Overlay specification for successful production is in the range one nanometer or even smaller. Consequently, materials designed into metrology systems of exposure or inspection tools need to fulfill ever tighter specification on the coefficient of thermal expansion (CTE). The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion, the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR®. This paper is focusing on the "Advanced Dilatometer" for determination of the CTE developed at SCHOTT in the recent years and introduced into production in Q1 2015. The achievement for improving the absolute CTE measurement accuracy and the reproducibility are described in detail. Those achievements are compared to the CTE measurement accuracy reported by the Physikalische Technische Bundesanstalt (PTB), the National Metrology Institute of Germany. The CTE homogeneity is of highest importance to achieve nanometer precision on larger scales. Additionally, the paper presents data on the short scale CTE homogeneity and its improvement in the last two years. The data presented in this paper will explain the capability of ZERODUR® to enable the extreme precision required for future generation of lithography equipment and processes.

  16. 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

  17. Tuning Aerosol Particle Size Distribution of Metered Dose Inhalers Using Cosolvents and Surfactants

    PubMed Central

    Saleem, Imran Y.; Smyth, Hugh D. C.

    2013-01-01

    Objectives. The purpose of these studies was to understand the influence of cosolvent and surfactant contributions to particle size distributions emitted from solution metered dose inhalers (pMDIs) based on the propellant HFA 227. Methods. Two sets of formulations were prepared: (a) pMDIs-HFA 227 containing cosolvent (5–15% w/w ethanol) with constant surfactant (pluronic) concentration and (b) pMDIs-HFA 227 containing surfactant (0–5.45% w/w pluronic) with constant cosolvent concentration. Particle size distributions emitted from these pMDIs were analyzed using aerodynamic characterization (inertial impaction) and laser diffraction methods. Results. Both cosolvent and surfactant concentrations were positively correlated with median particle sizes; that is, drug particle size increased with increasing ethanol and pluronic concentrations. However, evaluation of particle size distributions showed that cosolvent caused reduction in the fine particle mode magnitude while the surfactant caused a shift in the mode position. These findings highlight the different mechanisms by which these components influence droplet formation and demonstrate the ability to utilize the different effects in formulations of pMDI-HFA 227 for independently modulating particle sizes in the respirable region. Conclusion. Potentially, the formulation design window generated using these excipients in combination could be used to match the particle size output of reformulated products to preexisting pMDI products. PMID:23984381

  18. The effect of reducing alfalfa haylage particle size on cows in early lactation.

    PubMed

    Kononoff, P J; Heinrichs, A J

    2003-04-01

    The objective of this experiment was to evaluate effects of reducing forage particle size on cows in early lactation based on measurements of the Penn State Particle Separator (PSPS). Eight cannulated, multiparous cows averaging 19 +/- 4 d in milk and 642 +/- 45 kg BW were assigned to one of two 4 x 4 Latin Squares. During each of the 23-d periods, animals were offered one of four diets, which were chemically identical but included alfalfa haylage of different particle size; short (SH), mostly short (MSH), mostly long (MLG), and long (LG). Physically effective neutral detergent fiber (peNDF) was determined by measuring the amount of neutral detergent fiber retained on a 1.18 mm screen and was similar across diets (25.7, 26.2, 26.4, 26.7%) but the amount of particles >19.0 mm significantly decreased with decreasing particle size. Reducing haylage particle size increased dry matter intake linearly (23.3, 22.0, 20.9, 20.8 kg for SH, MSH, MLG, LG, respectively). Milk production and percentage fat did not differ across treatments averaging 35.5 +/- 0.68 kg milk and 3.32 +/- 0.67% fat, while a quadratic effect was observed for percent milk protein, with lowest values being observed for LG. A quadratic effect was observed for mean rumen pH (6.04, 6.15, 6.13, 6.09), while A:P ratio decreased linearly (2.75, 2.86, 2.88, 2.92) with decreasing particle size. Total time ruminating increased quadratically (467, 498, 486, 468 min/d), while time eating decreased linearly (262, 253, 298, 287 min/d) with decreasing particle size. Both eating and ruminating per unit of neutral detergent fiber intake decreased with reducing particle size (35.8, 36.7, 44.9, 45.6 min/kg; 19.9, 23.6, 23.5, 23.5 min/kg). Although chewing activity was closely related to forage particle size, effects on rumen pH were small, indicating factors other than particle size are critical in regulating pH when ration neutral detergent fiber met recommended levels. Feeding alfalfa haylage based rations of reduced

  19. NiCo2O4 particles with diamond-shaped hexahedron structure for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Yanfang; Hou, Xiaojuan; Zhang, Zengxing; Hai, Zhenyin; Xu, Hongyan; Cui, Danfeng; Zhuiykov, Serge; Xue, Chenyang

    2018-04-01

    Nickel cobalt oxide (NiCo2O4) particles with a diamond-shaped hexahedral porous sheet structure are successfully synthesized by a facile hydrothermal method, followed by calcination in one step. NiCo2O4-I and NiCo2O4-II particles are prepared using the same method with different contents of urea (CO(NH2)2) and ammonium fluoride (NH4F). The different morphologies of the NiCo2O4-I and NiCo2O4-II particles illustrate that CO(NH2)2 and NH4F play an important role in crystal growth. To verify the influence of NH4F and CO(NH2)2 on the morphology of the NiCo2O4 particles, the theory of crystal growth morphology is analyzed. The electrochemical measurements show that NiCo2O4 particles exhibit a high specific capacitance. At a current density of 1.0 mA cm-2, the mass specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes are 690.75 and 1710.9 F g-1, respectively, in a 6 M KOH aqueous electrolyte. The specific capacitances of the NiCo2O4-I and NiCo2O4-II electrodes remain ∼95.95% and ∼70.58% of the initial capacitance values after 5000 cycles, respectively. According to the two-electrode test, the NiCo2O4-II//AC asymmetric electrodes exhibited an ultrahigh energy density of 64.67 Wh kg-1 at the power density of 12 kW kg-1, demonstrating its excellent application potential as an electrode material for supercapacitors.

  20. Performance evaluation of bimodal thermite composites : nano- vs miron-scale particles

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

    Moore, K. M.; Pantoya, M.; Son, S. F.

    2004-01-01

    In recent years many studies of metastable interstitial composites (MIC) have shown vast combustion improvements over traditional thermite materials. The main difference between these two materials is the size of the fuel particles in the mixture. Decreasing the fuel size from the micron to nanometer range significantly increases the combustion wave speed and ignition sensitivity. Little is known, however, about the critical level of nano-sized fuel particles needed to enhance the performance of the traditional thermite. Ignition sensitivity experiments were performed using Al/MoO{sub 3} pellets at a theoretical maximum density of 50% (2 g/cm{sup 3}). The Al fuel particles weremore » prepared as bi-modal size distributions with micron (i.e., 4 and 20 {micro}m diameter) and nano-scale Al particles. The micron-scale Al was replaced in 10% increments by 80 nm Al particles until the fuel was 100% 80 nm Al. These bi-modal distributions allow the unique characteristics of nano-scale materials to be better understood. The pellets were ignited using a 50-W CO{sub 2} laser. High speed imaging diagnostics were used to measure ignition delay times, and micro-thermocouples were used to measure ignition temperatures. Combustion wave speeds were also examined.« less