WorldWideScience

Sample records for distinct monodisperse fractions

  1. Final Report for Fractionation and Separation of Polydisperse Nanoparticles into Distinct Monodisperse Fractions Using CO2 Expanded Liquids

    Energy Technology Data Exchange (ETDEWEB)

    Chistopher Roberts

    2007-08-31

    The overall objective of this project was to facilitate efficient fractionation and separation of polydisperse metal nanoparticle populations into distinct monodisperse fractions using the tunable solvent properties of gas expanded liquids. Specifically, the dispersibility of ligand-stabilized nanoparticles in an organic solution was controlled by altering the ligand-solvent interaction (solvation) by the addition of carbon dioxide (CO{sub 2}) gas as an antisolvent (thereby tailoring the bulk solvent strength) in a custom high pressure apparatus developed in our lab. This was accomplished by adjusting the CO{sub 2} pressure over the liquid dispersion, resulting in a simple means of tuning the nanoparticle precipitation by size. Overall, this work utilized the highly tunable solvent properties of organic/CO{sub 2} solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (ranging from 1 to 20 nm in size) into monodisperse fractions ({+-}1nm). Specifically, three primary tasks were performed to meet the overall objective. Task 1 involved the investigation of the effects of various operating parameters (such as temperature, pressure, ligand length and ligand type) on the efficiency of separation and fractionation of Ag nanoparticles. In addition, a thermodynamic interaction energy model was developed to predict the dispersibility of different sized nanoparticles in the gas expanded liquids at various conditions. Task 2 involved the extension of the experimental procedures identified in task 1 to the separation of other metal particles used in catalysis such as Au as well as other materials such as semiconductor particles (e.g. CdSe). Task 3 involved using the optimal conditions identified in tasks 1 and 2 to scale up the process to handle sample sizes of greater than 1 g. An experimental system was designed to allow nanoparticles of increasingly smaller sizes to be precipitated sequentially in a vertical series of high pressure vessels by

  2. Production of Monodisperse Nanoparticles and Application of Discrete-Monodisperse Model in Plasma Reactors

    International Nuclear Information System (INIS)

    Kim, Dong-Joo; Kim, Kyo-Seon; Zhao, Qian-Qiu

    2003-01-01

    The particle growth in plasma reactor were investigated by using the discrete-monodisperse (D-M) model for various process conditions. The monodisperse large sized particle distribution predicted by the D-M model are in good agreement with the large sized particles by the discrete-sectional model and also in the experiments by Shiratani et al. (1996). Some fractions of the small size particles are in a neutral state or even charged positively, but most of the large sized monodisperse particles are charged negatively. As the mass generation rate of monomers increases, the large sized particles grow more quickly and the production rate of nanoparticles of 100nm by plasma reactor increases. As the initial electron concentration or the monomer diameter increases, it takes longer time for the large sized particles to grow up to 100nm, but the large sized particle concentration of 100nm increases and the resulting production rate of large sized particles of 100nm increases. As the residence time increases, the time for the large sized particles to grow up to 100nm decreases and the large sized particle concentration of 100nm increases and, as a result, the production rate of large sized particles of 100nm increases. We propose that the plasma reactor can be a good candidate to produce monodisperse nanoparticles

  3. A procedure for partitioning bulk sediments into distinct grain-size fractions for geochemical analysis

    Science.gov (United States)

    Barbanti, A.; Bothner, Michael H.

    1993-01-01

    A method to separate sediments into discrete size fractions for geochemical analysis has been tested. The procedures were chosen to minimize the destruction or formation of aggregates and involved gentle sieving and settling of wet samples. Freeze-drying and sonication pretreatments, known to influence aggregates, were used for comparison. Freeze-drying was found to increase the silt/clay ratio by an average of 180 percent compared to analysis of a wet sample that had been wet sieved only. Sonication of a wet sample decreased the silt/clay ratio by 51 percent. The concentrations of metals and organic carbon in the separated fractions changed depending on the pretreatment procedures in a manner consistent with the hypothesis that aggregates consist of fine-grained organic- and metal-rich particles. The coarse silt fraction of a freeze-dried sample contained 20–44 percent higher concentrations of Zn, Cu, and organic carbon than the coarse silt fraction of the wet sample. Sonication resulted in concentrations of these analytes that were 18–33 percent lower in the coarse silt fraction than found in the wet sample. Sonication increased the concentration of lead in the clay fraction by an average of 40 percent compared to an unsonicated sample. Understanding the magnitude of change caused by different analysis protocols is an aid in designing future studies that seek to interpret the spatial distribution of contaminated sediments and their transport mechanisms.

  4. Aerosol fabrication methods for monodisperse nanoparticles

    Science.gov (United States)

    Jiang, Xingmao; Brinker, C Jeffrey

    2014-10-21

    Exemplary embodiments provide materials and methods for forming monodisperse particles. In one embodiment, the monodisperse particles can be formed by first spraying a nanoparticle-containing dispersion into aerosol droplets and then heating the aerosol droplets in the presence of a shell precursor to form core-shell particles. By removing either the shell layer or the nanoparticle core of the core-shell particles, monodisperse nanoparticles can be formed.

  5. Progress in Preparation of Monodisperse Polymer Microspheres

    Science.gov (United States)

    Zhang, Hongyan

    2017-12-01

    The monodisperse crosslinked polymer microspheres have attracted much attention because of their superior thermal and solvent resistance, mechanical strength, surface activity and adsorption properties. They are of wide prospects for using in many fields such as biomedicine, electronic science, information technology, analytical chemistry, standard measurement and environment protection etc. Functional polymer microspheres prepared by different methods have the outstanding surface property, quantum size effect and good potential future in applications with its designable structure, controlled size and large ratio of surface to volume. Scholars of all over the world have focused on this hot topic. The preparation method and research progress in functional polymer microspheres are addressed in the paper.

  6. Self-diffusion in monodisperse three-dimensional magnetic fluids by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dobroserdova, A.B. [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); Kantorovich, S.S., E-mail: alla.dobroserdova@urfu.ru [Ural Federal University, Lenin Av. 51, Ekaterinburg (Russian Federation); University of Vienna, Sensengasse 8, Vienna (Austria)

    2017-06-01

    In the present work we study the self-diffusion behaviour in the three-dimensional monodisperse magnetic fluids using the Molecular Dynamics Simulation and Density Functional Theory. The peculiarity of computer simulation is to study two different systems: dipolar and soft sphere ones. In the theoretical method, it is important to choose the approximation for the main structures, which are chains. We compare the theoretical results and the computer simulation data for the self-diffusion coefficient as a function of the particle volume fraction and magnetic dipole-dipole interaction parameter and find the qualitative and quantitative agreement to be good. - Highlights: • The paper deals with the study of the self-diffusion in monodisperse three-dimensional magnetic fluids. • The theoretical approach contains the free energy density functional minimization. • Computer simulations are performed by the molecular dynamics method. • We have a good qualitative and quantitative agreement between the theoretical results and computer simulation data.

  7. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

  8. The Generation And Properties Of Solid Monodisperse Aerosols Of ...

    African Journals Online (AJOL)

    A monodisperse aerosol generator (MAGE) was used to generate calibration or monodisperse aerosols containing stearic acid and carnauba wax. Some of the factors affecting the size of aerosol particles generated with the MAGE were determined. The factors include: temperature of operation of the MAGE, type and purity ...

  9. Logarithmic Exchange Kinetics in Monodisperse Copolymeric Micelles

    Science.gov (United States)

    García Daza, Fabián A.; Bonet Avalos, Josep; Mackie, Allan D.

    2017-06-01

    Experimental measurements of the relaxation kinetics of copolymeric surfactant exchange for micellar systems unexpectedly show a peculiar logarithmic decay. Several authors use polydispersity as an explanation for this behavior. However, in coarse-grained simulations that preserve microscopic details of the surfactants, we find evidence of the same logarithmic behavior. Since we use a strictly monodisperse distribution of chain lengths such a relaxation process cannot be attributed to polydispersity, but has to be caused by an inherent physical process characteristic of this type of system. This is supported by the fact that the decay is specifically logarithmic and not a power law with an exponent inherited from the particular polydispersity distribution of the sample. We suggest that the degeneracy of the energy states of the hydrophobic block in the core, which is broken on leaving the micelle, can qualitatively explain the broad distribution of energy barriers, which gives rise to the observed nonexponential relaxation.

  10. Synthesis and characterization of monodispersed silver nanoparticles

    Science.gov (United States)

    Jegatha Christy, A.; Umadevi, M.

    2012-09-01

    Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO3), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

  11. Synthesis and characterization of monodispersed silver nanoparticles

    International Nuclear Information System (INIS)

    Christy, A Jegatha; Umadevi, M

    2012-01-01

    Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO 3 ), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM). (paper)

  12. RNA sequencing supports distinct reactive oxygen species-mediated pathways of apoptosis by high and low size mass fractions of Bay leaf (Lauris nobilis) in HT-29 cells.

    Science.gov (United States)

    Rodd, Annabelle L; Ververis, Katherine; Sayakkarage, Dheeshana; Khan, Abdul W; Rafehi, Haloom; Ziemann, Mark; Loveridge, Shanon J; Lazarus, Ross; Kerr, Caroline; Lockett, Trevor; El-Osta, Assam; Karagiannis, Tom C; Bennett, Louise E

    2015-08-01

    Anti-proliferative and pro-apoptotic effects of Bay leaf (Laurus nobilis) in mammalian cancer and HT-29 adenocarcinoma cells have been previously attributed to effects of polyphenolic and essential oil chemical species. Recently, we demonstrated differentiated growth-regulating effects of high (HFBL) versus low molecular mass (LFBL) aqueous fractions of bay leaf and now confirm by comparative effects on gene expression, that HFBL and LFBL suppress HT-29 growth by distinct mechanisms. Induction of intra-cellular lesions including DNA strand breakage by extra-cellular HFBL, invoked the hypothesis that iron-mediated reactive oxygen species with capacity to penetrate cell membrane, were responsible for HFBL-mediated effects, supported by equivalent effects of HFBL in combination with γ radiation. Activities of HFBL and LFBL were interpreted to reflect differentiated responses to iron-mediated reactive oxygen species (ROS), occurring either outside or inside cells. In the presence of LFBL, apoptotic death was relatively delayed compared with HFBL. ROS production by LFBL mediated p53-dependent apoptosis and recovery was suppressed by promoting G1/S phase arrest and failure of cellular tight junctions. In comparison, intra-cellular anti-oxidant protection exerted by LFBL was absent for extra-cellular HFBL (likely polysaccharide-rich), which potentiated more rapid apoptosis by producing DNA double strand breaks. Differentiated effects on expression of genes regulating ROS defense and chromatic condensation by LFBL versus HFBL, were observed. The results support ferrous iron in cell culture systems and potentially in vivo, can invoke different extra-cellular versus intra-cellular ROS-mediated chemistries, that may be regulated by exogenous, including dietary species.

  13. Distribution of nutrients and antinutrients in milled fractions of chickpea and horse gram: seed coat phenolics and their distinct modes of enzyme inhibition.

    Science.gov (United States)

    Sreerama, Yadahally N; Neelam, Dennis A; Sashikala, Vadakkoot B; Pratape, Vishwas M

    2010-04-14

    Milled fractions of chickpea ( Cicer arietinum L.) and horse gram ( Macrotyloma uniflorum L. Verdc.) were evaluated for their nutritional and antinutritional characteristics. Crude protein content of these fractions ranged from 22.6-23.8 g 100(-1) g in cotyledon to 7.3-9.1 g 100(-1) g in seed coat fractions. The fat content of chickpea fractions (1.6-7.8 g 100(-1) g) was higher than that of horse gram fractions (0.6-2.6 g 100(-1) g). Crude fiber content was higher in seed coat fractions of both legumes than embryonic axe and cotyledon fractions. Seed coat fractions had high dietary fiber content (28.2-36.4 g 100(-1) g), made up of mainly insoluble dietary fiber. Most of the phytic acid and oligosaccharides were located in the cotyledon fractions, whereas phenolic compounds in higher concentrations were found in seed coats. Significantly higher concentrations of proteinaceous and phenolic inhibitors of digestive enzymes were found in cotyledon and seed coat fractions, respectively. The kinetic studies, using Michaelis-Menten and Lineweaver-Burk derivations, revealed that seed coat phenolics inhibit alpha-amylase activity by mixed noncompetitive (chickpea) and noncompetitive (horse gram) inhibition mechanisms. In the case of trypsin, chickpea and horse gram seed coat phenolics showed noncompetitive and uncompetitive modes of inhibition, respectively. These results suggest the wide variability in the nutrient and antinutrient composition in different milled fractions of legumes and potential utility of these fractions as ingredients in functional food product development.

  14. Can a droplet break up under flow without elongating? Fragmentation of smectic monodisperse droplets

    Science.gov (United States)

    Courbin, L.; Engl, W.; Panizza, P.

    2004-06-01

    We study the fragmentation under shear flow of smectic monodisperse droplets at high volume fraction. Using small angle light scattering and optical microscopy, we reveal the existence of a break-up mechanism for which the droplets burst into daughter droplets of the same size. Surprisingly, this fragmentation process, which is strain controlled and occurs homogeneously in the cell, does not require any transient elongation of the droplets. Systematic experiments as a function of the initial droplet size and the applied shear rate show that the rupture is triggered by an instability of the inner droplet structure.

  15. Characterization of a monodispersed aerosol exposure system for beagle dogs

    International Nuclear Information System (INIS)

    Cannon, W.C.; Herring, J.P.; Craig, D.K.

    1978-01-01

    A monodispersed aerosol exposure system for dogs is described and data are presented on aerosol depositions in the exposure system which could affect the aerosol presented to the animals by reducing the concentration and changing the particle size distribution

  16. A general approach for monodisperse colloidal perovskites, Chemistry of Materials

    NARCIS (Netherlands)

    Demirors, A.F.; Imhof, A.

    2009-01-01

    We describe a novel general method for synthesizing monodisperse colloidal perovskite particles at room temperature by postsynthesis addition of metal hydroxides to amorphous titania colloids. In previous work, we used titania particles to synthesize homogenously mixed silica-titania composite

  17. The distinction between chondroma and chondrosarcoma using chemical element mass fractions in tumors determined by neutron activation analysis as diagnostic markers

    International Nuclear Information System (INIS)

    Zaichick, Vladimir; Zaichick, Sofia

    2016-01-01

    The Ca, Cl, Mg, Na, and P content and Ca/P, Ca/Mg, Ca/Na, Cl/Ca, and Cl/Na ratios in tissue of intact bone, chondroma and chondrosarcoma were investigated by neutron activation analysis. It was shown that higher mass fraction of Cl and Na and also Cl/Na mass fraction ratio as well as lower Ca/Cl and Ca/Na mass fraction ratios are typical of the chondrosarcoma tissue compared to chondroma. Finally, it was proposed to use the estimation of such parameters as the Cl mass fraction and the Ca/Cl and Ca/Na mass fraction ratios as an additional test for differential diagnosis between chondroma and chondrosarcoma. (author)

  18. Meta-analysis of diffusion tensor imaging (DTI) studies shows altered fractional anisotropy occurring in distinct brain areas in association with depression

    LENUS (Irish Health Repository)

    Murphy, Melissa L

    2011-09-27

    Abstract Fractional anisotropy anomalies occurring in the white matter tracts in the brains of depressed patients may reflect microstructural changes underlying the pathophysiology of this disorder. We conducted a meta-analysis of fractional anisotropy abnormalities occurring in major depressive disorder using voxel-based diffusion tensor imaging studies. Using the Embase, PubMed and Google Scholar databases, 89 relevant data sets were identified, of which 7 (including 188 patients with major depressive disorder and 221 healthy controls) met our inclusion criteria. Authors were contacted to retrieve any additional data required. Coordinates were extracted from clusters of significant white matter fractional anisotropy differences between patients and controls. Relevant demographic, clinical and methodological variables were extracted from each study or obtained directly from authors. The meta-analysis was carried out using Signed Differential Mapping. Patients with depression showed decreased white matter fractional anisotropy values in the superior longitudinal fasciculus and increased fractional anisotropy values in the fronto-occipital fasciculus compared to controls. Using quartile and jackknife sensitivity analysis, we found that reduced fractional anisotropy in the left superior longitudinal fasciculus was very stable, with increases in the right fronto-occipital fasciculus driven by just one study. In conclusion, our meta-analysis revealed a significant reduction in fractional anisotropy values in the left superior longitudinal fasciculus, which may ultimately play an important role in the pathology of depression.

  19. Meta-analysis of diffusion tensor imaging studies shows altered fractional anisotropy occurring in distinct brain areas in association with depression.

    LENUS (Irish Health Repository)

    Murphy, Melissa L

    2011-09-01

    Fractional anisotropy anomalies occurring in the white matter tracts in the brains of depressed patients may reflect microstructural changes underlying the pathophysiology of this disorder. We conducted a meta-analysis of fractional anisotropy abnormalities occurring in major depressive disorder using voxel-based diffusion tensor imaging studies. Using the Embase, PubMed and Google Scholar databases, 89 relevant data sets were identified, of which 7 (including 188 patients with major depressive disorder and 221 healthy controls) met our inclusion criteria. Authors were contacted to retrieve any additional data required. Coordinates were extracted from clusters of significant white matter fractional anisotropy differences between patients and controls. Relevant demographic, clinical and methodological variables were extracted from each study or obtained directly from authors. The meta-analysis was carried out using Signed Differential Mapping. Patients with depression showed decreased white matter fractional anisotropy values in the superior longitudinal fasciculus and increased fractional anisotropy values in the fronto-occipital fasciculus compared to controls. Using quartile and jackknife sensitivity analysis, we found that reduced fractional anisotropy in the left superior longitudinal fasciculus was very stable, with increases in the right fronto-occipital fasciculus driven by just one study. In conclusion, our meta-analysis revealed a significant reduction in fractional anisotropy values in the left superior longitudinal fasciculus, which may ultimately play an important role in the pathology of depression.

  20. Optical properties of monodispersive FePt nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.J.; Lo, C.C.H. [Ames Laboratory, Iowa State University, Ames, IA 50011 (United States); Yu, A.C.C. [Sony Corporation, Sendai Technology Center, 3-4-1 Sakuragi, Miyagi 985-0842 (Japan); Fan, M. [Center for Sustainable Environmental Technologies, Iowa State University, Ames, IA 50011 (United States)

    2004-10-01

    The optical properties of monodispersive FePt nanoparticle films were investigated using spectroscopic ellipsometry in the energy range of 1.5 to 5.5 eV. The monodispersive FePt nanoparticle film was stabilized on a Si substrate by means of an organosilane coupling film, resulting in the formation of a (Si/SiO{sub 2}/APTS/FePt nanoparticles monolayer) structure. Multilayer optical models were employed to study the contribution of the FePt nanoparticles to the measured optical properties of the monodispersive FePt nanoparticle film, and to estimate the optical properties of the FePt nanoparticle layer. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Distinct 238U/235U ratios and REE patterns in plutonic and volcanic angrites: Geochronologic implications and evidence for U isotope fractionation during magmatic processes

    Science.gov (United States)

    Tissot, François L. H.; Dauphas, Nicolas; Grove, Timothy L.

    2017-09-01

    Angrites are differentiated meteorites that formed between 4 and 11 Myr after Solar System formation, when several short-lived nuclides (e.g., 26Al-26Mg, 53Mn-53Cr, 182Hf-182W) were still alive. As such, angrites are prime anchors to tie the relative chronology inferred from these short-lived radionuclides to the absolute Pb-Pb clock. The discovery of variable U isotopic composition (at the sub-permil level) calls for a revision of Pb-Pb ages calculated using an ;assumed; constant 238U/235U ratio (i.e., Pb-Pb ages published before 2009-2010). In this paper, we report high-precision U isotope measurement for six angrite samples (NWA 4590, NWA 4801, NWA 6291, Angra dos Reis, D'Orbigny, and Sahara 99555) using multi-collector inductively coupled plasma mass-spectrometry and the IRMM-3636 U double-spike. The age corrections range from -0.17 to -1.20 Myr depending on the samples. After correction, concordance between the revised Pb-Pb and Hf-W and Mn-Cr ages of plutonic and quenched angrites is good, and the initial (53Mn/55Mn)0 ratio in the Early Solar System (ESS) is recalculated as being (7 ± 1) × 10-6 at the formation of the Solar System (the error bar incorporates uncertainty in the absolute age of Calcium, Aluminum-rich inclusions - CAIs). An uncertainty remains as to whether the Al-Mg and Pb-Pb systems agree in large part due to uncertainties in the Pb-Pb age of CAIs. A systematic difference is found in the U isotopic compositions of quenched and plutonic angrites of +0.17‰. A difference is also found between the rare earth element (REE) patterns of these two angrite subgroups. The δ238U values are consistent with fractionation during magmatic evolution of the angrite parent melt. Stable U isotope fractionation due to a change in the coordination environment of U during incorporation into pyroxene could be responsible for such a fractionation. In this context, Pb-Pb ages derived from pyroxenes fraction should be corrected using the U isotope composition

  2. Segmented block copolymers with monodisperse aramide end-segments

    NARCIS (Netherlands)

    Araichimani, A.; Gaymans, R.J.

    2008-01-01

    Segmented block copolymers were synthesized using monodisperse diaramide (TT) as hard segments and PTMO with a molecular weight of 2 900 g · mol-1 as soft segments. The aramide: PTMO segment ratio was increased from 1:1 to 2:1 thereby changing the structure from a high molecular weight multi-block

  3. Microscopy evidence of the face-centered cubic arrangement of monodisperse polystyrene nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hui [School of Science, Beijing Jiaotong University, Beijing 100044 (China)]. E-mail: zhanghui14305@sohu.com; Duan Renguan [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li Fan [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Tang Qing [Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Li Wenchao [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2007-07-01

    This paper reports a scanning electron microscopy (SEM) investigation of polystyrene artificial opal achieved through self-assembly of monodisperse polystyrene nanospheres with a diameter of 250 nm from colloidal suspension after being ambient dried. A detailed analysis of the SEM images verifies that the face-centered cubic (fcc) phase is the most stable one for the polystyrene opal prepared. This finding provides a strong support for, by using polystyrene opal as template, fabricating a photonic crystal with inverse fcc structure of full band gap if the refractive index contrast is higher than 2.8 and the filling fraction of the high index materials is between 0.2 and 0.3.

  4. Microscopy evidence of the face-centered cubic arrangement of monodisperse polystyrene nanospheres

    International Nuclear Information System (INIS)

    Zhang Hui; Duan Renguan; Li Fan; Tang Qing; Li Wenchao

    2007-01-01

    This paper reports a scanning electron microscopy (SEM) investigation of polystyrene artificial opal achieved through self-assembly of monodisperse polystyrene nanospheres with a diameter of 250 nm from colloidal suspension after being ambient dried. A detailed analysis of the SEM images verifies that the face-centered cubic (fcc) phase is the most stable one for the polystyrene opal prepared. This finding provides a strong support for, by using polystyrene opal as template, fabricating a photonic crystal with inverse fcc structure of full band gap if the refractive index contrast is higher than 2.8 and the filling fraction of the high index materials is between 0.2 and 0.3

  5. Major- and minor-metal composition of three distinct solid material fractions associated with Juan de Fuca hydrothermal fluids (northeast Pacific), and calculation of dilution fluid samples

    Science.gov (United States)

    Hinkley, T.K.; Seeley, J.L.; Tatsumoto, M.

    1988-01-01

    Three distinct types of solid material are associated with each sample of the hydrothermal fluid that was collected from the vents of the Southern Juan de Fuca Ridge. The solid materials appear to be representative of deposits on ocean floors near mid-ocean ridges, and interpretation of the chemistry of the hydrothermal solutions requires understanding of them. Sr isotopic evidence indicates that at least two and probably all three of these solid materials were removed from the solution with which they are associated, by precipitation or adsorption. This occurred after the "pure" hydrothermal fluid was diluted and thoroughly mixed with ambient seawater. The three types of solid materials, are, respectively, a coarse Zn- and Fe-rich material with small amounts of Na and Ca; a finer material also rich in Zn and Fe, but with alkali and alkaline-earth metals; and a scum composed of Ba or Zn, with either considerable Fe or Si, and Sr. Mineral identification is uncertain because of uncertain anion composition. Only in the cases of Ba and Zn were metal masses greater in solid materials than in the associated fluids. For all other metals measured, masses in fluids dwarf those in solids. The fluids themselves contain greater concentrations of all metals measured, except Mg, than seawater. We discuss in detail the relative merits of two methods of determining the mixing proportions of "pure" hydrothermal solution and seawater in the fluids, one based on Sr isotopes, and another previously used method based on Mg concentrations. Comparison of solute concentrations in the several samples shows that degree of dilution of "pure" hydrothermal solutions by seawater, and amounts of original solutes that were removed from it as solid materials, are not related. There is no clear evidence that appreciable amounts of solid materials were not conserved (lost) either during or prior to sample collection. ?? 1988.

  6. A co-flow-focusing monodisperse microbubble generator

    KAUST Repository

    Zhang, Jiaming; Li, Erqiang; Thoroddsen, Sigurdur T

    2014-01-01

    We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

  7. A co-flow-focusing monodisperse microbubble generator

    KAUST Repository

    Zhang, Jiaming

    2014-02-14

    We use a simple and inexpensive microfluidic device, which is based on microscope glass slides and two tapered glass capillaries, to produce monodisperse microbubbles. The innermost capillary used for transporting the gas is inserted into the second capillary, with its 2 μm sharp tip aligned with the center of the converging-diverging throat of the second capillary. This configuration provides a small and smooth gas flow rate, and a high velocity gradient at the tube outlet. Highly monodisperse microbubbles with diameters ranging from 3.5 to 60 microns have been successfully produced at a rate of up to 40 kHz. A simple scaling law, which is based on the capillary number and liquid-to-gas flow rate ratio, successfully predicts the bubble size. © 2014 IOP Publishing Ltd.

  8. Synthesis of Monodisperse Iron Oxide Nanoparticles without Surfactants

    Directory of Open Access Journals (Sweden)

    Xiao-Chen Yang

    2014-01-01

    Full Text Available Monodisperse iron oxide nanoparticles could be successfully synthesized with two kinds of precipitants through a precipitation method. As-prepared nanoparticles in the size around 10 nm with regular spherical-like shape were achieved by adjusting pH values. NaOH and NH3·H2O were used as two precipitants for comparison. The average size of nanoparticles with NH3·H2O precipitant got smaller and represented better dispersibility, while nanoparticles with NaOH precipitant represented better magnetic property. This work provided a simple method without using any organic solvents, organic metal salts, or surfactants which could easily obtain monodisperse nanoparticles with tunable morphology.

  9. The self-assembly of monodisperse nanospheres within microtubes

    International Nuclear Information System (INIS)

    Zheng Yuebing; Juluri, Bala Krishna; Huang, Tony Jun

    2007-01-01

    Self-assembled monodisperse nanospheres within microtubes have been fabricated and characterized. In comparison with colloidal crystals formed on planar substrates, colloidal nanocrystals self-assembled in microtubes demonstrate high spatial symmetry in their optical transmission and reflection properties. The dynamic self-assembly process inside microtubes is investigated by combining temporal- and spatial-spectrophotometric measurements. The understanding of this process is achieved through both experimentally recorded reflection spectra and finite difference time domain (FDTD)-based simulation results

  10. Laboratory evaluation of a vibrating orifice monodisperse aerosol generator

    International Nuclear Information System (INIS)

    Everitt, N.M.; Snelling, K.W.

    1985-02-01

    The Berglund-Liu vibrating orifice aerosol generator is capable of producing monodisperse particles in the diameter range 5 to 50 μm. Experiments have been carried out to set up and evaluate such a generator for the preparation of standard liquid (olive oil) and solid (methylene blue) aerosols in the size range 8 to 13 μm. Modifications have been made to the apparatus to improve its performance and increase its particle output. (author)

  11. Morphologically and size uniform monodisperse particles and their shape-directed self-assembly

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Joshua E.; Bell, Howard Y.; Ye, Xingchen; Murray, Christopher Bruce

    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). 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.

  12. Highly Selective Synthesis of Catalytically Active Monodisperse Rhodium Nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Grass, M.E.; Kuhn, J.N.; Tao, F.; Habas, S.E.; Huang, W.; Yang, P.; Somorjai, G.A.

    2009-02-21

    Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metal NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl

  13. Transmission and fractionation of micro-sized particle suspensions

    NARCIS (Netherlands)

    Brans, G.B.P.W.; Dinther, van A.M.C.; Odum, B.; Schroën, C.G.P.H.; Boom, R.M.

    2007-01-01

    In processes aimed at the fractionation of a multi-component feed stream, transmission of particles through the membrane is at least as important as retention of larger particles. In this paper, we describe the mechanisms of transmission of mono-disperse latex particles through a polymer membrane.

  14. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz; Hassager, Ole

    2005-01-01

    The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole (PS52K) and 103 kg/mole (PS103K), and for three bidisperse polystyrene melts. The bidisperse melts consist of PS103K or PS52K and a monodisperse...... (closed loop proportional regulator) using the laser in such a way that the stretch rate at the neck is kept constant. The rheometer has been described in more detail in (A. Bach, H.K. Rasmussen and O. Hassager, Journal of Rheology, 47 (2003) 429). PS390K show a decrease in the steady viscosity as a power......-law function of the elongational rate (A. Bach, K. Almdal, H.K. Rasmussen and O. Hassager, Macromolecules 36 (2003) 5174). PS52K and PS103K show that the steady viscosity has a maximum that is respectively 100% and 50% above 3 times the zero-shear-rate viscosity. The bidisperse melts show a significant...

  15. Flow and Failure in Extension of Monodisperse Polymer Melts

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.

    is commonly referred to be of either brittle (e.g. cohesive type) or of liquid (e.g. necking type) nature. Here the focus will be on monodisperse polymers, to study numerically the sample flow dynamics in dual wind-up extensional rheometers. The computations are within the ideas of the microstructural......It is well known that failure or rupture phenomenon appears in the extension of polymer melts. These appear not only as failure in extension rheometers, but also as sharkskin, developments of holes in thin polymeric films etc. Sometime these ruptures appear spontaneous as well. The rupture...... 'interchain pressure' theory based on the molecular stress function constitutive model for the polymer melt flow. The purpose is twofold. Primarily to present to what extend the experimentally observed failure, appearing during or after (e.g. as a spontaneous failure) extension, can be explained within...

  16. Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

    International Nuclear Information System (INIS)

    Seto, Takafumi; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto

    2006-01-01

    Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism

  17. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    International Nuclear Information System (INIS)

    Shao-Peng, Zhu; Shao-Chun, Tang; Xiang-Kang, Meng

    2009-01-01

    Silver nanoparticles with an average size of about 20 nm are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method. The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability. (cross-disciplinary physics and related areas of science and technology)

  18. Laser ablation synthesis of monodispersed magnetic alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Seto, Takafumi, E-mail: t.seto@aist.go.jp; Koga, Kenji; Akinaga, Hiroyuki; Takano, Fumiyoshi; Orii, Takaaki; Hirasawa, Makoto [National Institute of Advanced Industrial Science and Technology (AIST), Research Consortium for Synthetic Nano-Function Materials Project (SYNAF) (Japan)

    2006-08-15

    Monodispersed CoPt alloy nanoparticles were synthesized by a pulsed laser ablation (PLA) technique coupled with a low-pressure operating differential mobility analyzer (LP-DMA). The CoPt alloy nanoparticles were generated by laser ablating a solid Co-Pt target. In CoPt alloy nanoparticles synthesized from a target with a Co composition of 75 at%, the nanoparticle surfaces were covered by an oxide layer and exhibited a core-shell structure. In contrast, no shell was observed in particles generated from a target with a Co:Pt ratio of 50:50 at%. According to an EDX analysis, the compositions of the individual nanoparticles were almost the same as that of the target material. Finally, the magnetic hysteresis loops of the CoPt alloy nanoparticles exhibited ferromagnetism.

  19. Monodisperse Magneto-Fluorescent Bifunctional Nanoprobes for Bioapplications

    Science.gov (United States)

    Zhang, Hongwang; Huang, Heng; Pralle, Arnd; Zeng, Hao

    2013-03-01

    We present the work on the synthesis of dye-doped monodisperse Fe/SiO2 core/shell nanoparticles as bifunctional probes for bioapplications. Magnetic nanoparticles (NP) have been widely studied as nano-probes for bio-imaging, sensing as well as for cancer therapy. Among all the NPs, Fe NPs have been the focus because they have very high magnetization. However, Fe NPs are usually not stable in ambient due to the fast surface oxidation of the NPs. On the other hand, dye molecules have long been used as probes for bio-imaging. But they are sensitive to environmental conditions. It requires passivation for both so that they can be stable for applications. In this work, monodisperse Fe NPs with sizes ranging from 13-20 nm have been synthesized through the chemical thermal-decomposition in a solution. Silica shells were then coated on the Fe NPs by a two-phase oil-in-water method. Dye molecules were first bonded to a silica precursor and then encapsulated into the silica shell during the coating process. The silica shells protect both the Fe NPs and dye molecules, which makes them as robust probes. The dye doped Fe/SiO2 core/shell NPs remain both highly magnetic and highly fluorescent. The stable dye doped Fe/SiO2NPs have been used as a dual functional probe for both magnetic heating and local nanoscale temperature sending, and their performance will be reported. Research supported by NSF DMR 0547036, DMR1104994.

  20. Distinctive Citizenship

    DEFF Research Database (Denmark)

    Kaur, Ravinder

    2009-01-01

    The refugee, in India's Partition history, appears as an enigmatic construct - part pitiful, part heroic, though mostly shorn of agency - representing the surface of the human tragedy of Partition. Yet this archetype masks the undercurrent of social distinctions that produced hierarchies of post...

  1. Quantitation of MRI sensitivity to quasi-monodisperse microbubble contrast agents for spatially resolved manometry.

    Science.gov (United States)

    Bencsik, Martin; Al-Rwaili, Amgad; Morris, Robert; Fairhurst, David J; Mundell, Victoria; Cave, Gareth; McKendry, Jonathan; Evans, Stephen

    2013-11-01

    The direct in-vivo measurement of fluid pressure cannot be achieved with MRI unless it is done with the contribution of a contrast agent. No such contrast agents are currently available commercially, whilst those demonstrated previously only produced qualitative results due to their broad size distribution. Our aim is to quantitate then model the MR sensitivity to the presence of quasi-monodisperse microbubble populations. Lipid stabilised microbubble populations with mean radius 1.2 ± 0.8 μm have been produced by mechanical agitation. Contrast agents with increasing volume fraction of bubbles up to 4% were formed and the contribution the bubbles bring to the relaxation rate was quantitated. A periodic pressure change was also continuously applied to the same contrast agent, until MR signal changes were only due to bubble radius change and not due to a change in bubble density. The MR data compared favourably with the prediction of an improved numerical simulation. An excellent MR sensitivity of 23 % bar(-1) has been demonstrated. This work opens up the possibility of generating microbubble preparations tailored to specific applications with optimised MR sensitivity, in particular MRI based in-vivo manometry. Copyright © 2012 Wiley Periodicals, Inc.

  2. Template synthesis of highly crystalline and monodisperse iron oxide pigments of nanosize

    International Nuclear Information System (INIS)

    Sreeram, Kalarical Janardhanan; Indumathy, Ramasamy; Rajaram, Ananthanarayanan; Nair, Balachandran Unni; Ramasami, Thirumalachari

    2006-01-01

    Synthesis of highly crystalline and monodisperse iron oxide nanoparticles is reported. The separation of Fe centers through site-specific binding to a polysaccharide-alginate matrix enables the generation of particles with a monodisperse or narrow size distribution character, resulting in transparent pigments. Site-specific interactions coupled with gel like character of alginate is proposed as the mechanism behind generation of lower particle sizes. Alginate-Fe complexes developed were subjected to heat treatment to provide for crystalline character and development of hematite (α-Fe 2 O 3 ). Conditions most ideal for achieving monodispersity and lower sizes have been optimized and confirmed through microscopic and photon correlation spectroscopic measurements

  3. Preparation and magnetic properties of magnetic photonic crystal by using monodisperse polystyrene covered Fe3O4 nanoparticles onto glass substrate

    Science.gov (United States)

    Azizi, Zahra Sadat; Tehranchi, Mohammad Mehdi; Vakili, Seyed Hamed; Pourmahdian, Saeed

    2018-05-01

    Engineering approach towards combined photonic band gap properties and magnetic/polymer composite particles, attract considerable attention of researchers due to their unique properties. In this research, two different magnetic particles were prepared by nearly monodisperse polystyrene spheres as bead with two concentrations of Fe3O4 nanoparticles to prepare magnetic photonic crystals (MPCs). The crystal surfaces and particles morphology were investigated employing scanning electron microscopy and transmission electron microscopy. The volume fraction of magnetic material embedded into colloidal spheres and their morphology was found to be a key parameter in the optical and magneto-optical properties of transparent MPC.

  4. Monodispersed Zinc Oxide Nanoparticle-Dye Dyads and Triads

    Energy Technology Data Exchange (ETDEWEB)

    Gladfelter, Wayne L. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry; Blank, David A. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry; Mann, Kent R. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry

    2017-06-22

    events at a fundamental level. This was combined with the synthesis of a broad range of sensitizers that provide systematic variation of the energetics, excited state dynamics, structure and interfacial bonding. The key is that the monodisperse nature and high dispersibility of the ZnO NCs made these experiments reproducible; in essence, the measurements were on discrete molecular species rather than on the complicated mixtures that resulted from the typical fabrication of functional photovoltaic cells. The monodispersed nature of the NCs also allowed the use of quantum confinement to investigate the role of donor/acceptor energetic alignment in chemically identical systems. The results added significantly to our basic understanding of energy and charge transfer events at molecule-semiconductor interfaces and will help the R&D community realize zinc oxide's full potential in solar cell applications.

  5. Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

    KAUST Repository

    Li, Erqiang; Zhang, Jiaming; Thoroddsen, Sigurdur T

    2013-01-01

    of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions

  6. Application of monodisperse fibers and discs to evaluation of the aerodynamic particle sizer

    International Nuclear Information System (INIS)

    Hoover, M.D.; Lipowicz, P.J.; Hanson, R.W.; Yeh, H.C.; Casalnuovo, S.A.

    1988-01-01

    Monodisperse fibers, μm in width and lengths of 5, 10, 20, and 40 μm, as well as monodisperse discs, 2 4 8, or 12 μm in diameter, were prepared using an integrated circuit microchip fabrication technique. Particles were silicon dioxide with thickness of 1 μm. Examination of the particles using a scanning electron microscope showed that they were uniform in shape, with well-defined edges. The particles were suspended in distilled water and aerosolized with a Lovelace nebullizer. The monodisperse particles were used to evaluate the TSI Aerodynamic Particle Sizer (APS). Carbon fibers that were monodisperse in diameter (count median diameter 3.42 μm, geometric standard deviation 1.06) and polydisperse in length (count median length = 28 μm, geometric standard deviation 2.2) were also used. The APS was found to be insensitive to fiber length and only weakly sensitive to disc diameter. (author)

  7. Facile and Scalable Synthesis of Monodispersed Spherical Capsules with a Mesoporous Shell

    KAUST Repository

    Qi, Genggeng

    2010-05-11

    Monodispersed HMSs with tunable particle size and shell thickness were successfully synthesized using relatively concentrated polystyrene latex templates and a silica precursor in a weakly basic ethanol/water mixture. The particle size of the capsules can vary from 100 nm to micrometers. These highly engineered monodispersed capsules synthesized by a facile and scalable process may find applications in drug delivery, catalysis, separationm or as biological and chemical microreactors. © 2010 American Chemical Society.

  8. Scalable fractionation of iron oxide nanoparticles using a CO2 gas-expanded liquid system

    International Nuclear Information System (INIS)

    Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B.

    2015-01-01

    Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO 2 gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

  9. Facile Synthesis of Monodisperse Gold Nanocrystals Using Virola oleifera

    Science.gov (United States)

    Milaneze, Bárbara A.; Oliveira, Jairo P.; Augusto, Ingrid; Keijok, Wanderson J.; Côrrea, Andressa S.; Ferreira, Débora M.; Nunes, Otalíbio C.; Gonçalves, Rita de Cássia R.; Kitagawa, Rodrigo R.; Celante, Vinícius G.; da Silva, André Romero; Pereira, Ana Claudia H.; Endringer, Denise C.; Schuenck, Ricardo P.; Guimarães, Marco C. C.

    2016-10-01

    The development of new routes and strategies for nanotechnology applications that only employ green synthesis has inspired investigators to devise natural systems. Among these systems, the synthesis of gold nanoparticles using plant extracts has been actively developed as an alternative, efficient, cost-effective, and environmentally safe method for producing nanoparticles, and this approach is also suitable for large-scale synthesis. This study reports reproducible and completely natural gold nanocrystals that were synthesized using Virola oleifera extract. V. oleifera resin is rich in epicatechin, ferulic acid, gallic acid, and flavonoids (i.e., quercetin and eriodictyol). These gold nanoparticles play three roles. First, these nanoparticles exhibit remarkable stability based on their zeta potential. Second, these nanoparticles are functionalized with flavonoids, and third, an efficient, economical, and environmentally friendly mechanism can be employed to produce green nanoparticles with organic compounds on the surface. Our model is capable of reducing the resin of V. oleifera, which creates stability and opens a new avenue for biological applications. This method does not require painstaking conditions or hazardous agents and is a rapid, efficient, and green approach for the fabrication of monodisperse gold nanoparticles.

  10. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

    International Nuclear Information System (INIS)

    Cao Feng; Li Dongxu

    2010-01-01

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe 3+ , which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  11. Biotemplate synthesis of monodispersed iron phosphate hollow microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Cao Feng; Li Dongxu, E-mail: dongxuli@njut.edu.c [College of Materials Science and Engineering, Nanjing University of Technology, Jiangsu Nanjing 210009 (China)

    2010-03-15

    Monodispersed iron phosphate hollow microspheres with a high degree of crystallization were prepared through a facile in situ deposition method using rape pollen grains as a biotemplate. The functional group on the surface of the pollen grains could adsorb Fe{sup 3+}, which provided the nucleation sites for growth of iron phosphate nanoparticles. After being sintered at 600 deg. C for 10 h, the pollen grains were removed and iron phosphate hollow microspheres were obtained. A scanning electron microscope and x-ray diffraction were applied to characterize the morphology and crystalline structure of the pollen grains, iron phosphate-coated pollen grains and iron phosphate hollow microspheres. Differential scanning calorimetry and thermogravity analyses were performed to investigate the thermal behavior of the iron phosphate-coated pollen grains during the calcinations. Energy dispersive spectroscopy and Fourier transform infrared spectroscopy were utilized to investigate the interaction between the pollen grains and iron phosphate. The effect of the pollen wall on the surface morphology of these iron phosphate hollow microspheres was also proven in this work.

  12. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

    2008-09-01

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  13. Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

    Directory of Open Access Journals (Sweden)

    Sumeet Kumar

    2015-02-01

    Full Text Available In the present study, monodispersed CeO2 nanoparticles (NPs of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD, field emission scanning electron microscope (FE-SEM, high resolution transmission electron microscopy (HR-TEM, ultra-violet visible (UV-VIS spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms, coercivity (Hc and retentivity (Mr are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

  14. Monodisperse selenium-substituted hydroxyapatite: Controllable synthesis and biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jianpeng [School of Civil Engineering, Xi' an University of Architecture and Technology, Shaanxi 710055 (China); Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Zheng, Xiaoyan; Li, Hui; Fan, Daidi [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Song, Zhanping [School of Civil Engineering, Xi' an University of Architecture and Technology, Shaanxi 710055 (China); Ma, Haixia [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China); Hua, Xiufu, E-mail: hua_xiufu@163.com [Department of Scientific Research and Development, Tsinghua University, Beijing 100084 (China); Hui, Junfeng, E-mail: huijunfeng@126.com [Shaanxi Key Laboratory of Degradable Biomedical Materials, Shaanxi R& D Center of Biomaterials and Fermentation Engineering, School of Chemical and Engineering, Northwest University, Xi' an, 710069 (China)

    2017-04-01

    Hydroxyapatite (HA) is the major inorganic component of natural bone tissue. As an essential trace element, selenium involves in antioxidation and anticancer of human body. So far, ion-doped hydroxyapatites (HAs) are widely investigated owing to their great applications in field of biomaterial, biological labeling. In this paper, series of monodisperse HA doped with SeO{sub 3}{sup 2−} (SeHA) was successfully synthesized based on the liquid–solid–solution (LSS) strategy. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive spectrometer (EDS). The results indicated that the SeO{sub 3}{sup 2−} doping level of the Se/(P + Se) molar ratio of 0– 0.4 can be requisitely controlled, and the morphology of SeHA nanoparticles varied from nanorods to nanoneedles with increasing Se/(P + Se) molar ratio. Significantly, the as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells, showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone. - Highlights: • Series of SeO{sub 3}{sup 2−} doped HA nanorods or/and nanoneedles were successfully synthesized. • The morphology of the HA nanocrystals can be easily controlled by changing the Se/(P + Se) molar ratio. • The as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells. • Showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone.

  15. Formation of monodisperse mesoporous silica microparticles via spray-drying.

    Science.gov (United States)

    Waldron, Kathryn; Wu, Winston Duo; Wu, Zhangxiong; Liu, Wenjie; Selomulya, Cordelia; Zhao, Dongyuan; Chen, Xiao Dong

    2014-03-15

    In this work, a protocol to synthesize monodisperse mesoporous silica microparticles via a unique microfluidic jet spray-drying route is reported for the first time. The microparticles demonstrated highly ordered hexagonal mesostructures with surface areas ranging from ~900 up to 1500 m(2)/g and pore volumes from ~0.6 to 0.8 cm(3)/g. The particle size could be easily controlled from ~50 to 100 μm from the same diameter nozzle via changing the initial solute content, or changing the drying temperature. The ratio of the surfactant (CTAB) and silica (TEOS), and the amount of water in the precursor were found to affect the degree of ordering of mesopores by promoting either the self-assembly of the surfactant-silica micelles or the condensation of the silica as two competing processes in evaporation induced self-assembly. The drying rate and the curvature of particles also affected the self-assembly of the mesostructure. The particle mesostructure is not influenced by the inlet drying temperature in the range of 92-160 °C, with even a relatively low temperature of 92 °C producing highly ordered mesoporous microparticles. The spray-drying derived mesoporous silica microparticles, while of larger sizes and more rapidly synthesized, showed a comparable performance with the conventional mesoporous silica MCM-41 in controlled release of a dye, Rhodamine B, indicating that these spray dried microparticles could be used for the immobilisation and controlled release of small molecules. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Monodisperse selenium-substituted hydroxyapatite: Controllable synthesis and biocompatibility

    International Nuclear Information System (INIS)

    Sun, Jianpeng; Zheng, Xiaoyan; Li, Hui; Fan, Daidi; Song, Zhanping; Ma, Haixia; Hua, Xiufu; Hui, Junfeng

    2017-01-01

    Hydroxyapatite (HA) is the major inorganic component of natural bone tissue. As an essential trace element, selenium involves in antioxidation and anticancer of human body. So far, ion-doped hydroxyapatites (HAs) are widely investigated owing to their great applications in field of biomaterial, biological labeling. In this paper, series of monodisperse HA doped with SeO 3 2− (SeHA) was successfully synthesized based on the liquid–solid–solution (LSS) strategy. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive spectrometer (EDS). The results indicated that the SeO 3 2− doping level of the Se/(P + Se) molar ratio of 0– 0.4 can be requisitely controlled, and the morphology of SeHA nanoparticles varied from nanorods to nanoneedles with increasing Se/(P + Se) molar ratio. Significantly, the as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells, showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone. - Highlights: • Series of SeO 3 2− doped HA nanorods or/and nanoneedles were successfully synthesized. • The morphology of the HA nanocrystals can be easily controlled by changing the Se/(P + Se) molar ratio. • The as-synthesized SeHA nanocrystals exhibit a low cytotoxicity for osteoblastic cells. • Showing exciting potentials for application in artificial scaffold materials inhibiting of tumor growth in bone

  17. Ambiguity assessment of small-angle scattering curves from monodisperse systems.

    Science.gov (United States)

    Petoukhov, Maxim V; Svergun, Dmitri I

    2015-05-01

    A novel approach is presented for an a priori assessment of the ambiguity associated with spherically averaged single-particle scattering. The approach is of broad interest to the structural biology community, allowing the rapid and model-independent assessment of the inherent non-uniqueness of three-dimensional shape reconstruction from scattering experiments on solutions of biological macromolecules. One-dimensional scattering curves recorded from monodisperse systems are nowadays routinely utilized to generate low-resolution particle shapes, but the potential ambiguity of such reconstructions remains a major issue. At present, the (non)uniqueness can only be assessed by a posteriori comparison and averaging of repetitive Monte Carlo-based shape-determination runs. The new a priori ambiguity measure is based on the number of distinct shape categories compatible with a given data set. For this purpose, a comprehensive library of over 14,000 shape topologies has been generated containing up to seven beads closely packed on a hexagonal grid. The computed scattering curves rescaled to keep only the shape topology rather than the overall size information provide a `scattering map' of this set of shapes. For a given scattering data set, one rapidly obtains the number of neighbours in the map and the associated shape topologies such that in addition to providing a quantitative ambiguity measure the algorithm may also serve as an alternative shape-analysis tool. The approach has been validated in model calculations on geometrical bodies and its usefulness is further demonstrated on a number of experimental X-ray scattering data sets from proteins in solution. A quantitative ambiguity score (a-score) is introduced to provide immediate and convenient guidance to the user on the uniqueness of the ab initio shape reconstruction from the given data set.

  18. FRACTIONAL BANKING

    OpenAIRE

    Maria Klimikova

    2010-01-01

    Understanding the reasons of the present financial problems lies In understanding the substance of fractional reserve banking. The substance of fractional banking is in lending more money than the bankers have. Banking of partial reserves is an alternative form which links deposit banking and credit banking. Fractional banking is causing many unfavorable economic impacts in the worldwide system, specifically an inflation.

  19. Syringe-vacuum microfluidics: A portable technique to create monodisperse emulsions.

    Science.gov (United States)

    Abate, Adam R; Weitz, David A

    2011-03-16

    We present a simple method for creating monodisperse emulsions with microfluidic devices. Unlike conventional approaches that require bulky pumps, control computers, and expertise with device physics to operate devices, our method requires only the microfluidic device and a hand-operated syringe. The fluids needed for the emulsion are loaded into the device inlets, while the syringe is used to create a vacuum at the device outlet; this sucks the fluids through the channels, generating the drops. By controlling the hydrodynamic resistances of the channels using hydrodynamic resistors and valves, we are able to control the properties of the drops. This provides a simple and highly portable method for creating monodisperse emulsions.

  20. Ultrasound-driven Megahertz Faraday Waves for Generation of Monodisperse Micro Droplets and Applications

    Science.gov (United States)

    Tsai, Chen S.; Mao, Rong W.; Lin, Shih K.; Tsai, Shirley C.; Boss, Gerry; Brenner, Matt; Smaldone, Gerry; Mahon, Sari; Shahverdi, Kaveh; Zhu, Yun

    Our theoretical findings on instability of Faraday waves at megahertz (MHz) drive frequency and realization of silicon-based MHz multiple-Fourier horn ultrasonic nozzles (MFHUNs) together have enabled generation of mono-disperse droplets of controllable diameter (2.5-6.0 μm) at very low electrical drive power (generator has imminent application to pulmonary (inhalation) drug delivery and other potential applications. Here an update of advances on analysis and design of the MHz MFHUNs and the underlying physical mechanism for generation of mono-disperse micro droplets, and the nebulizer platform for application to detoxification of cyanide poisoning are presented.

  1. Emulsifier-free emulsion polymerization produces highly charged, monodisperse particles for near infrared photonic crystals.

    Science.gov (United States)

    Reese, Chad E; Asher, Sanford A

    2002-04-01

    We have developed emulsifier-free, emulsion polymerization recipes for the synthesis of highly charged, monodisperse latex particles of diameters between 500 and 1100 nm. These latexes consist of poly[styrene-(co-2-hydroxyethyl methacrylate)] spherical particles whose surfaces are functionalized with sulfate and carboxylic acid groups. These highly charged, monodisperse particles readily self-assemble into robust, three-dimensionally ordered crystalline colloidal array photonic crystals that Bragg diffract light in the near infrared spectral region. By altering the particle number density, the diffraction wavelength can be tuned from approximately 1000 to approximately 4000 nm.

  2. Scalable fractionation of iron oxide nanoparticles using a CO{sub 2} gas-expanded liquid system

    Energy Technology Data Exchange (ETDEWEB)

    Vengsarkar, Pranav S.; Xu, Rui; Roberts, Christopher B., E-mail: croberts@eng.auburn.edu [Auburn University, Department of Chemical Engineering (United States)

    2015-10-15

    Iron oxide nanoparticles exhibit highly size-dependent physicochemical properties that are important in applications such as catalysis and environmental remediation. In order for these size-dependent properties to be effectively harnessed for industrial applications scalable and cost-effective techniques for size-controlled synthesis or size separation must be developed. The synthesis of monodisperse iron oxide nanoparticles can be a prohibitively expensive process on a large scale. An alternative involves the use of inexpensive synthesis procedures followed by a size-selective processing technique. While there are many techniques available to fractionate nanoparticles, many of the techniques are unable to efficiently fractionate iron oxide nanoparticles in a scalable and inexpensive manner. A scalable apparatus capable of fractionating large quantities of iron oxide nanoparticles into distinct fractions of different sizes and size distributions has been developed. Polydisperse iron oxide nanoparticles (2–20 nm) coated with oleic acid used in this study were synthesized using a simple and inexpensive version of the popular coprecipitation technique. This apparatus uses hexane as a CO{sub 2} gas-expanded liquid to controllably precipitate nanoparticles inside a 1L high-pressure reactor. This paper demonstrates the operation of this new apparatus and for the first time shows the successful fractionation results on a system of metal oxide nanoparticles, with initial nanoparticle concentrations in the gram-scale. The analysis of the obtained fractions was performed using transmission electron microscopy and dynamic light scattering. The use of this simple apparatus provides a pathway to separate large quantities of iron oxide nanoparticles based upon their size for use in various industrial applications.

  3. Fractional thermoelasticity

    CERN Document Server

    Povstenko, Yuriy

    2015-01-01

    This book is devoted to fractional thermoelasticity, i.e. thermoelasticity based on the heat conduction equation with differential operators of fractional order. Readers will discover how time-fractional differential operators describe memory effects and space-fractional differential operators deal with the long-range interaction. Fractional calculus, generalized Fourier law, axisymmetric and central symmetric problems and many relevant equations are featured in the book. The latest developments in the field are included and the reader is brought up to date with current research.  The book contains a large number of figures, to show the characteristic features of temperature and stress distributions and to represent the whole spectrum of order of fractional operators.  This work presents a picture of the state-of-the-art of fractional thermoelasticity and is suitable for specialists in applied mathematics, physics, geophysics, elasticity, thermoelasticity and engineering sciences. Corresponding sections of ...

  4. Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres

    Indian Academy of Sciences (India)

    Assembly of Fe3O4 nanoparticles on SiO2 monodisperse spheres. K C BARICK and D BAHADUR*. Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay,. Mumbai 400 076, India. Abstract. The assembly of superparamagnetic Fe3O4 nanoparticles on submicroscopic SiO2 ...

  5. Tri-block copolymers with mono-disperse crystallizable diamide segments: synthesis, analysis and rheological properties

    NARCIS (Netherlands)

    Araichimani, A.; Gaymans, R.J.

    2008-01-01

    Tri-block copolymers with polyether mid-segments and mono-disperse amide end segments were synthesized, analyzed and some properties studied. The end segment was an aromatic diamide (diaramide, TΦB). The polyether mid-segment was a difunctional poly(tetramethylene oxide) (PTMO, 1000 and 2900 g/mol).

  6. Hydrophilic segmented block copolymers based on poly(ethylene oxide) and monodisperse amide segments

    NARCIS (Netherlands)

    Husken, D.; Feijen, Jan; Gaymans, R.J.

    2007-01-01

    Segmented block copolymers based on poly(ethylene oxide) (PEO) flexible segments and monodisperse crystallizable bisester tetra-amide segments were made via a polycondensation reaction. The molecular weight of the PEO segments varied from 600 to 4600 g/mol and a bisester tetra-amide segment (T6T6T)

  7. Room temperature vortex fluidic synthesis of monodispersed amorphous proto-vaterite.

    Science.gov (United States)

    Peng, Wenhong; Chen, Xianjue; Zhu, Shenmin; Guo, Cuiping; Raston, Colin L

    2014-10-11

    Monodispersed particles of amorphous calcium carbonate (ACC) 90 to 200 nm in diameter are accessible at room temperature in ethylene glycol and water using a vortex fluidic device (VFD). The ACC material is stable for at least two weeks under ambient conditions.

  8. Numerical simulations of flows through fixed networks of monodispersed and bi-dispersed spheres, for moderate Reynolds numbers; Simulations numeriques d'ecoulements a travers des reseaux fixes de spheres monodisperses et bidisperses, pour des nombres de Reynolds moderes

    Energy Technology Data Exchange (ETDEWEB)

    Massol, A.

    2004-02-15

    The application of statistically averaged two-fluid models for the simulation of complex indus- trial two-phase flows requires the development of adequate models for the drag force exerted on the inclusions and the interfacial heat exchange. This task becomes problematic at high volume fractions of the dispersed phase. The quality of the simulation strongly depends upon the inter- facial exchange terms, starting with the steady drag force. For example, an accurate modelling of the drag force is therefore a crucial point to simulate the expansion of dense fluidized beds. Most models used to study the exchange terms between particles and fluids are based on the interaction between an isolated particle and a surrounding gas. Those models are clearly not adequate in cases where the volume fraction of particles increases and particle-particle interactions become important. Studying such cases is a complex task because of the multiple possible configurations. While the interaction between an isolated sphere and a gas depends only on the particle size and the slip velocity between gas and particles, the interaction between a cloud of particles and a gas depends on many more parameters: size and velocity distribution of particles, relative position of particles. Even if the particles keep relative fixed positions, there is an infinite number of combinations to construct such an array. The objective of the present work is to perform steady and unsteady simulations of the flow in regular arrays of fixed particles in order to analyze the influence of the size and distributions of spheres on drag force and heat transfer (the array of spheres can be either monodispersed, either bi-dispersed). Several authors have studied the drag exerted on the spheres, but only for low Reynolds numbers and/or solid volume fractions close to the packed limit. Moreover some discrepancies are observed between the different studies. On top of that, all existing studies are limited to steady flows

  9. Fractional charges

    International Nuclear Information System (INIS)

    Saminadayar, L.

    2001-01-01

    20 years ago fractional charges were imagined to explain values of conductivity in some materials. Recent experiments have proved the existence of charges whose value is the third of the electron charge. This article presents the experimental facts that have led theorists to predict the existence of fractional charges from the motion of quasi-particles in a linear chain of poly-acetylene to the quantum Hall effect. According to the latest theories, fractional charges are neither bosons nor fermions but anyons, they are submitted to an exclusive principle that is less stringent than that for fermions. (A.C.)

  10. High-speed monodisperse droplet generation by ultrasonically controlled micro-jet breakup

    Science.gov (United States)

    Frommhold, Philipp Erhard; Lippert, Alexander; Holsteyns, Frank Ludwig; Mettin, Robert

    2014-04-01

    A liquid jet that is ejected from a nozzle into air will disintegrate into drops via the well-known Plateau-Rayleigh instability within a certain range of Ohnesorge and Reynolds numbers. With the focus on the micrometer scale, we investigate the control of this process by superimposing a suitable ultrasonic signal, which causes the jet to break up into a very precise train of monodisperse droplets. The jet leaves a pressurized container of liquid via a small orifice of about 20 μm diameter. The break-up process and the emerging droplets are recorded via high-speed imaging. An extended parameter study of exit speed and ultrasonic frequency is carried out for deionized water to evaluate the jet's state and the subsequent generation of monodisperse droplets. Maximum exit velocities obtained reach almost 120 m s-1, and frequencies have been applied up to 1.8 MHz. Functionality of the method is confirmed for five additional liquids for moderate jet velocities 38 m s-1. For the uncontrolled jet disintegration, the drop size spectra revealed broad distributions and downstream drop growth by collision, while the acoustic control generated monodisperse droplets with a standard deviation less than 0.5 %. By adjustment of the acoustic excitation frequency, drop diameters could be tuned continuously from about 30 to 50 μm for all exit speeds. Good agreement to former experiments and theoretical approaches is found for the relation of overpressure and jet exit speed, and for the observed stability regions of monodisperse droplet generation in the parameter plane of jet speed and acoustic excitation frequency. Fitting of two free parameters of the general theory to the liquids and nozzles used is found to yield an even higher precision. Furthermore, the high-velocity instability limit of regular jet breakup described by von Ohnesorge has been superseded by more than a factor of two without entering the wind-induced instability regime, and monodisperse droplet generation was

  11. Fractional fermions

    International Nuclear Information System (INIS)

    Jackiw, R.; Massachusetts Inst. of Tech., Cambridge; Massachusetts Inst. of Tech., Cambridge

    1984-01-01

    The theory of fermion fractionization due to topologically generated fermion ground states is presented. Applications to one-dimensional conductors, to the MIT bag, and to the Hall effect are reviewed. (author)

  12. Intracellular Cadmium Isotope Fractionation

    Science.gov (United States)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  13. Simple and inexpensive microfluidic devices for the generation of monodisperse multiple emulsions

    KAUST Repository

    Li, Erqiang

    2013-12-16

    Droplet-based microfluidic devices have become a preferred versatile platform for various fields in physics, chemistry and biology. Polydimethylsiloxane soft lithography, the mainstay for fabricating microfluidic devices, usually requires the usage of expensive apparatus and a complex manufacturing procedure. Here, we report the design and fabrication of simple and inexpensive microfluidic devices based on microscope glass slides and pulled glass capillaries, for generating monodisperse multiple emulsions. The advantages of our method lie in a simple manufacturing procedure, inexpensive processing equipment and flexibility in the surface modification of the designed microfluidic devices. Different types of devices have been designed and tested and the experimental results demonstrated their robustness for preparing monodisperse single, double, triple and multi-component emulsions. © 2014 IOP Publishing Ltd.

  14. Design of monodisperse and well-defined polypeptide-based polyvalent inhibitors of anthrax toxin.

    Science.gov (United States)

    Patke, Sanket; Boggara, Mohan; Maheshwari, Ronak; Srivastava, Sunit K; Arha, Manish; Douaisi, Marc; Martin, Jacob T; Harvey, Ian B; Brier, Matthew; Rosen, Tania; Mogridge, Jeremy; Kane, Ravi S

    2014-07-28

    The design of polyvalent molecules, presenting multiple copies of a specific ligand, represents a promising strategy to inhibit pathogens and toxins. The ability to control independently the valency and the spacing between ligands would be valuable for elucidating structure-activity relationships and for designing potent polyvalent molecules. To that end, we designed monodisperse polypeptide-based polyvalent inhibitors of anthrax toxin in which multiple copies of an inhibitory toxin-binding peptide were separated by flexible peptide linkers. By tuning the valency and linker length, we designed polyvalent inhibitors that were over four orders of magnitude more potent than the corresponding monovalent ligands. This strategy for the rational design of monodisperse polyvalent molecules may not only be broadly applicable for the inhibition of toxins and pathogens, but also for controlling the nanoscale organization of cellular receptors to regulate signaling and the fate of stem cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

    Science.gov (United States)

    Morcrette, Mélissa; Ortiz, Guillermo; Tallegas, Salomé; Joisten, Hélène; Tiron, Raluca; Baron, Thierry; Hou, Yanxia; Lequien, Stéphane; Bsiesy, Ahmad; Dieny, Bernard

    2017-07-01

    This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material.

  16. Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

    International Nuclear Information System (INIS)

    Morcrette, Mélissa; Ortiz, Guillermo; Joisten, Hélène; Dieny, Bernard; Tallegas, Salomé; Baron, Thierry; Bsiesy, Ahmad; Tiron, Raluca; Hou, Yanxia; Lequien, Stéphane

    2017-01-01

    This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material. (paper)

  17. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    Science.gov (United States)

    Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

    2017-03-01

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  18. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun; Ju, Yanyun [Wuhan University of Technology, School of Materials Science and Engineering (China); Guo, Yi [Wuhan University of Technology, Center for Materials Research and Analysis (China); Xiong, Chuanxi; Dong, Lijie, E-mail: dong@whut.edu.cn [Wuhan University of Technology, School of Materials Science and Engineering (China)

    2017-03-15

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  19. Environmentally friendly synthesis of highly monodisperse biocompatible gold nanoparticles with urchin-like shape.

    Science.gov (United States)

    Lu, Lehui; Ai, Kelong; Ozaki, Yukihiro

    2008-02-05

    We report a facile and environmentally friendly strategy for high-yield synthesis of highly monodisperse gold nanoparticles with urchin-like shape. A simple protein, gelatin, was first used for the control over shape and orientation of the gold nanoparticles. These nanoparticles, ready to use for biological systems, are promising in the optical imaging-based disease diagnostics and therapy because of their tunable surface plasmon resonance (SPR) and excellent surface-enhanced Raman scattering (SERS) activity.

  20. Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

    International Nuclear Information System (INIS)

    Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

    2006-01-01

    A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

  1. Organic inorganic hybrid coating (poly(methyl methacrylate)/monodisperse silica)

    Science.gov (United States)

    Rubio, E.; Almaral, J.; Ramírez-Bon, R.; Castaño, V.; Rodríguez, V.

    2005-04-01

    Polymethylmethacrylate-silica hybrid coatings were prepared from methyl methacrylate and monodisperse colloidal silica prepared by the Stöber method. The surfaces of the spheres were successfully modified by chemical reaction with 3-(trimethoxysilyl) propyl methacrylate (TMSPM) to compatibilise the organic and inorganic components of the precursor solution mixture. The coatings were deposited by dip-coating on glass substrates. They result with good properties of homogeneity, optical transparence, hardness and adhesion.

  2. Preparation of monodisperse porous silica particles using poly(glycidyl methacrylate) microspheres as a template

    Czech Academy of Sciences Publication Activity Database

    Grama, Silvia; Horák, Daniel

    2015-01-01

    Roč. 64, Suppl. 1 (2015), S11-S17 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : microspheres * monodisperse * silica Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.643, year: 2015 http://www.biomed.cas.cz/physiolres/pdf/64%20Suppl%201/64_S11.pdf

  3. Temperature dependence of exchange anisotropy in monodisperse cobalt nanoparticles with a cobalt oxide shell

    International Nuclear Information System (INIS)

    Spasova, M.; Wiedwald, U.; Farle, M.; Radetic, T.; Dahmen, U.; Hilgendorff, M.; Giersig, M.

    2004-01-01

    Exchange anisotropy was studied by SQUID magnetometry on an array of monodisperse colloidal nanoparticles consisting of a 7-8 nm diameter FCC Co core covered with a 2-2.5 nm thick FCC CoO shell. Temperature-dependent measurements of the exchange bias field show that the exchange anisotropy vanishes when a magnetic field was applied during cooling below 150 K. The suppression of exchange anisotropy is due to uncompensated interfacial antiferromagnetic spins

  4. Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography

    Science.gov (United States)

    Tsyurupa, M. P.; Blinnikova, Z. K.; Il'in, M. M.; Davankov, V. A.; Parenago, O. O.; Pokrovskii, O. I.; Usovich, O. I.

    2015-11-01

    Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.

  5. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Energy Technology Data Exchange (ETDEWEB)

    Wen Li [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Lin Zhonghua [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Gu Pingying [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China); Zhou Jianzhang [Xiamen University, State Key Laboratory of Physical Chemistry of Solid Surfaces (China); Yao Bingxing [Xiamen University, School of Life Sciences (China); Chen Guoliang; Fu Jinkun, E-mail: wenli_1976@163.co [Xiamen University, Department of Chemistry, College of Chemistry and Chemical Engineering (China)

    2009-02-15

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 {sup o}C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 {+-} 0.8 nm size were formed by using Bacillus megatherium D01.

  6. Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

    International Nuclear Information System (INIS)

    Shen, Shou-Cang; Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai; Tan, Reginald B.H.

    2011-01-01

    Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: → Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. → Strong positive charge was created by aminopropyl-modification. → Capability for immobilization of negatively charged protein was enhanced. → Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by 13 C and 29 Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

  7. Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin, E-mail: zhangxy@iccas.ac.cn, E-mail: ylsong@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Lab of Organic Solids, Laboratory of New Materials, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2011-10-21

    In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO{sub 3} mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10{sup -8}-8.76 x 10{sup -8} {Omega} m after thermal treatment at 160 {sup 0}C for 30 min, which was about five times that of bulk silver (1.586 x 10{sup -8} {Omega} m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

  8. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    International Nuclear Information System (INIS)

    Wen Li; Lin Zhonghua; Gu Pingying; Zhou Jianzhang; Yao Bingxing; Chen Guoliang; Fu Jinkun

    2009-01-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 o C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (<2.5 nm), hold the shape of spherical nanoparticles, and promote the monodispersity of nanoparticles. Through the modulation of reaction time and the use of thiol, monodispersed spherical gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  9. Synthesis of monodisperse silver nanoparticles for ink-jet printed flexible electronics

    International Nuclear Information System (INIS)

    Zhang Zhiliang; Zhang Xingye; Xin Zhiqing; Deng Mengmeng; Wen Yongqiang; Song Yanlin

    2011-01-01

    In this study, monodisperse silver nanoparticles were synthesized with a new reduction system consisting of adipoyl hydrazide and dextrose at ambient temperature. By this facile and rapid approach, high concentration monodisperse silver nanoparticles were obtained on a large scale at low protectant/AgNO 3 mass ratio which was highly beneficial to low cost and high conductivity. Based on the synthesized monodisperse silver nanoparticles, conductive inks were prepared with water, ethanol and ethylene glycol as solvents, and were expected to be more environmentally friendly. A series of electrocircuits were fabricated by ink-jet printing silver nanoparticle ink on paper substrate with a commercial printer, and they had low resistivity in the range of 9.18 x 10 -8 -8.76 x 10 -8 Ω m after thermal treatment at 160 0 C for 30 min, which was about five times that of bulk silver (1.586 x 10 -8 Ω m). Moreover, a radio frequency identification (RFID) antenna was fabricated by ink-jet printing, and 6 m wireless identification was realized after an Alien higgs-3 chip was mounted on the printed antenna by the flip-chip method. These flexible electrocircuits produced by ink-jet printing would have enormous potential for low cost electrodes and sensor devices.

  10. Optimization of a simple technique for preparation of monodisperse poly(lactide-co-glycolide) nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Fuminori, E-mail: fuminoito@spice.ocn.ne.jp [Tokyo Metropolitan University, Department of Applied Chemistry, Graduate School of Urban Environmental Sciences (Japan)

    2016-09-15

    In this study, we report the optimization of a solvent evaporation technique for preparing monodisperse poly-(lactide-co-glycolide) (PLGA) nanospheres, from a mixture of solvents composed of ethanol and PVA solution. Various experimental conditions were investigated in order to control the particle size and size distribution of the nanospheres. In addition, nanospheres containing rifampicin (RFP, an antituberculosis drug), were prepared using PLGA of various molecular weights, to study the effects of RFP as a model hydrophobic drug. The results showed that a higher micro-homogenizer stirring rate facilitated the preparation of monodisperse PLGA nanospheres with a low coefficient of variation (~20 %), with sizes below 200 nm. Increasing the PLGA concentration from 0.1 to 0.5 g resulted in an increase in the size of the obtained nanospheres from 130 to 174 nm. The molecular weight of PLGA had little effect on the particle sizes and particle size distributions of the nanospheres. However, the drug loading efficiencies of the obtained RFP/PLGA nanospheres decreased when the molecular weight of PLGA was increased. Based on these experiments, an optimized technique was established for the preparation of monodisperse PLGA nanospheres, using the method developed by the authors.Graphical Abstract.

  11. Sonochemical synthesis of (3-aminopropyl)triethoxysilane-modified monodispersed silica nanoparticles for protein immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Shou-Cang, E-mail: shen_shoucang@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Ng, Wai Kiong; Chia, Leonard; Dong, Yuan-Cai [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Tan, Reginald B.H., E-mail: reginald_tan@ices.a-star.edu.sg [Institute of Chemical and Engineering Sciences, A-STAR (Agency for Science, Technology and Research), 1 Pesek Road, Jurong Island, Singapore 627833 (Singapore); Department of Chemical and Biomolecular Engineering, The National University of Singapore, 4 Engineering Drive 4, Singapore 117576 (Singapore)

    2011-10-15

    Graphical abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by rapid sonochemical co-condensation to achieve high capability for protein immobilization. Highlights: {yields} Amino-modified monodispersed silica nanoparticles were synthesized by rapid co-condensation. {yields} Strong positive charge was created by aminopropyl-modification. {yields} Capability for immobilization of negatively charged protein was enhanced. {yields} Electrostatic interaction between proteins and surface contributed to the enhanced adsorption. -- Abstract: 3-Aminopropyltriethoxysilane modified monodispersed silica nanoparticles were synthesized by a rapid sonochemical co-condensation synthesis procedure. The chemical nature of surface organic modifier on the obtained modified silica nanoparticle was characterized by {sup 13}C and {sup 29}Si MAS Nuclear Magnetic Resonance (NMR) spectroscopies, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA)- differential scanning calorimetry (DSC). Due to the strengthened positive surface charge of the silica nanoparticles by the modification with aminopropyl groups, the capability for bovine serum albumin (BSA) adsorption was significantly increased as compared with bare silica nanoparticles. 80 mg/g BSA was adsorbed on modified silica nanoparticles, whereas only 20 mg/g BSA could be loaded on pure silica nanoparticles. The enhanced positive surface charge repelled proteins with net positive charge and the modified silica nanoparticles exhibited negligible adsorption of lysozyme, thus a selective adsorption of proteins could be achieved.

  12. Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

    Science.gov (United States)

    Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

    2008-09-02

    Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.

  13. Mystery Fractions

    Science.gov (United States)

    Bhattacharyya, Sonalee; Namakshi, Nama; Zunker, Christina; Warshauer, Hiroko K.; Warshauer, Max

    2016-01-01

    Making math more engaging for students is a challenge that every teacher faces on a daily basis. These authors write that they are constantly searching for rich problem-solving tasks that cover the necessary content, develop critical-thinking skills, and engage student interest. The Mystery Fraction activity provided here focuses on a key number…

  14. Fraction Reduction through Continued Fractions

    Science.gov (United States)

    Carley, Holly

    2011-01-01

    This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.

  15. Gram-scale fractionation of nanodiamonds by density gradient ultracentrifugation

    KAUST Repository

    Peng, Wei

    2013-01-01

    Size is a defining characteristic of nanoparticles; it influences their optical and electronic properties as well as their interactions with molecules and macromolecules. Producing nanoparticles with narrow size distributions remains one of the main challenges to their utilization. At this time, the number of practical approaches to optimize the size distribution of nanoparticles in many interesting materials systems, including diamond nanocrystals, remains limited. Diamond nanocrystals synthesized by detonation protocols-so-called detonation nanodiamonds (DNDs)-are promising systems for drug delivery, photonics, and composites. DNDs are composed of primary particles with diameters mainly <10 nm and their aggregates (ca. 10-500 nm). Here, we introduce a large-scale approach to rate-zonal density gradient ultracentrifugation to obtain monodispersed fractions of nanoparticles in high yields. We use this method to fractionate a highly concentrated and stable aqueous solution of DNDs and to investigate the size distribution of various fractions by dynamic light scattering, analytical ultracentrifugation, transmission electron microscopy and powder X-ray diffraction. This fractionation method enabled us to separate gram-scale amounts of DNDs into several size ranges within a relatively short period of time. In addition, the high product yields obtained for each fraction allowed us to apply the fractionation method iteratively to a particular size range of particles and to collect various fractions of highly monodispersed primary particles. Our method paves the way for in-depth studies of the physical and optical properties, growth, and aggregation mechanism of DNDs. Applications requiring DNDs with specific particle or aggregate sizes are now within reach. © 2013 The Royal Society of Chemistry.

  16. Quantum Distinction: Quantum Distinctiones!

    OpenAIRE

    Zeps, Dainis

    2009-01-01

    10 pages; How many distinctions, in Latin, quantum distinctiones. We suggest approach of anthropic principle based on anthropic reference system which should be applied equally both in theoretical physics and in mathematics. We come to principle that within reference system of life subject of mathematics (that of thinking) should be equated with subject of physics (that of nature). For this reason we enter notions of series of distinctions, quantum distinction, and argue that quantum distinct...

  17. Synthesis, fractionation, and thin film processing of nanoparticles using the tunable solvent properties of carbon dioxide gas expanded liquids

    Science.gov (United States)

    Anand, Madhu

    nanoparticle populations. This study details the influence of various factors on the size separation process, such as the types of nanoparticles, ligand type and solvent type as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. This size selective precipitation technique was also applied to fractionate and separate polydisperse dispersions of CdSe/ZnS semiconductor nanocrystals into very distinct size and color fractions based solely on the pressure tunable solvent properties of CO2 expanded liquids. This size selective precipitation of nanoparticles is achieved by finely tuning the solvent strength of the CO2/organic solvent medium by simply adjusting the applied CO2 pressure. These subtle changes affect the balance between osmotic repulsive and van der Waals attractive forces thereby allowing fractionation of the nanocrystals into multiple narrow size populations. Thermodynamic analysis of nanoparticle size selective fractionation was performed to develop a theoretical model based on the thermodynamic properties of gas expanded liquids. We have used the general phenomenon of nanoparticle precipitation with CO2 expanded liquids to create dodecanethiol stabilized gold nanoparticle thin films. This method utilizes CO2 as an anti-solvent for low defect, wide area gold nanoparticle film formation employing monodisperse gold nanoparticles. Dodecanethiol stabilized gold particles are precipitated from hexane by controllably expanding the solution with carbon dioxide. Subsequent addition of carbon dioxide as a dense supercritical fluid then provides for removal of the organic solvent while avoiding the dewetting effects common to evaporating solvents. Unfortunately, the use of carbon dioxide as a neat solvent in nanoparticles synthesis and processing is limited by the very poor solvent strength of dense phase CO2. As a result, most current techniques employed to synthesize and disperse nanoparticles in neat carbon dioxide

  18. Force chains in monodisperse spherical particle assemblies: Three-dimensional measurements using neutrons

    Science.gov (United States)

    Wensrich, C. M.; Kisi, E. H.; Luzin, V.; Garbe, U.; Kirstein, O.; Smith, A. L.; Zhang, J. F.

    2014-10-01

    The full triaxial stress state within individual particles in a monodisperse spherical granular assembly has been measured. This was made possible by neutron imaging and computed tomography combined with neutron diffraction strain measurement techniques and associated stress reconstruction. The assembly in question consists of 549 precision steel ball bearings under an applied axial load of 85 MPa in a cylindrical die. Clear evidence of force chains was observed in terms of both the shape of the probability distribution function for normal stresses and the network formed by highly loaded particles. An extensive analysis of the source and magnitude of uncertainty in these measurements is also presented.

  19. High Performance Affinity Chromatography of Antithrombin III Based on Monodisperse Poly (glycidyl methacrylate) Beads

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new approach for the separation of antithrombin III with high performance affinity chromatography (HPAC) was described. A novel monodisperse,non-porous,cross-linked poly (glycidyl methacrylate) beads (PGMA) were used as the affinity support. With the water-soluble carbodiimide,heparin was linked covalently to amino-PGMA-beads,which was prepared by amination of PGMA. The adsorbent obtained exhibits high binding activity to antithrombin III (ATIII),good resolution and excellent mechanical properties and can be used under high flow rate.

  20. Synthesis of Monodisperse CdSe QDs using Controlled Growth Temperatures

    International Nuclear Information System (INIS)

    Noor Razinah Rahmat; Akrajas Ali Umar; Muhammad Yahya; Muhamad Mat Salleh; Mohammad Hafizuddin Jumali

    2011-01-01

    The effect of growth temperatures on size of CdSe quantum dots (QDs) has been investigated. CdSe QDs were synthesized using thermolysis of organometallics precursor route using wet chemical method. The growth temperature was varied from 260-310 degree Celsius with growth period fixed at 60 s. As the growth temperature increased, the monodispersed CdSe QDs with diameter in the range 3-7 nm were obtained. Both absorption and PL spectra of the QDs revealed a strong red-shift supporting the increment size of QDs with the rise of growth temperature. (author)

  1. The Synthesis, Characterization and Catalytic Reaction Studies of Monodisperse Platinum Nanoparticles in Mesoporous Oxide Materials

    Energy Technology Data Exchange (ETDEWEB)

    Rioux, Robert M. [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    A catalyst design program was implemented in which Pt nanoparticles, either of monodisperse size and/or shape were synthesized, characterized and studied in a number of hydrocarbon conversion reactions. The novel preparation of these materials enables exquisite control over their physical and chemical properties that could be controlled (and therefore rationally tuned) during synthesis. The ability to synthesize rather than prepare catalysts followed by thorough characterization enable accurate structure-function relationships to be elucidated. This thesis emphasizes all three aspects of catalyst design: synthesis, characterization and reactivity studies. The precise control of metal nanoparticle size, surface structure and composition may enable the development of highly active and selective heterogeneous catalysts.

  2. Note: A simple vibrating orifice monodisperse droplet generator using a hard drive actuator arm

    Energy Technology Data Exchange (ETDEWEB)

    Kosch, Sebastian, E-mail: skosch@mie.utoronto.ca, E-mail: ashgriz@mie.utoronto.ca; Ashgriz, Nasser, E-mail: skosch@mie.utoronto.ca, E-mail: ashgriz@mie.utoronto.ca [Department of Industrial and Mechanical Engineering, University of Toronto, Toronto, Ontario M5S 3G8 (Canada)

    2015-04-15

    We propose that the rotary voice coil actuators found in magnetic hard drives are fit to supercede loudspeakers as expedient vibration sources in the laboratory setting. A specific use case is the excitation of a liquid jet to induce controlled breakup into monodisperse droplets. Like loudspeakers, which are typically used for prototyping such devices, hard drive actuators are cheap and ubiquitous, but they are less unwieldy and supply greater amplitudes without producing noise. Frequencies between 0 and 17 kHz, and likely beyond, can be reproduced reliably. No machining tools or amplifying electronics are needed for the construction and operation of the presented droplet generator.

  3. Synthesis of Monodispersed Spherical Single Crystalline Silver Particles by Wet Chemical Process; Shisshiki kagakuho ni yoru tanbunsankyujo tankesshoginryushi no gose

    Energy Technology Data Exchange (ETDEWEB)

    Ueyama, Ryousuke.; Harada, Masahiro.; Ueyama, Tamotsu.; Harada, Akio. [Daiken Chemistry Industry Corporation, Osaka (Japan); Yamamoto, Takashi. [National Defence Academy, Kanagawa (Japan). Dept. of Electrical Engineering; Shiosaki, Tadashi. [Nara Institute of Science and Technology, Nara (Japan). Graduate School of Materials Science; Kuribayashi, Kiyoshi. [Teikyo University of Science and Technology, Yamanashi (Japan). Dept. of Materials

    1999-01-01

    Ultrafine silver monodispersed particle were prepared by wet chemical process. To decrease the reduction speed, an important factor in generating monodispersed particles is to control the following three factors: synthesis temperature, concentration of aggregation-relaxing agent added, and concentration of silver nitrate solution. Synthesis of monodispersed spherical Ag particles, used as metal powders for electrode, became possible using the nucleus grouwth reaction method. This process also allowed the control of the diameter of the powder particles. The silver particles were distributed in ta narrow particle diameter range with on average of 0.5 {mu}m. Transmission electron microscopy (TEM) revealed that single-crystalline silver particles were prepared by the present method. (author)

  4. Monodispersed macroporous architecture of nickel-oxide film as an anode material for thin-film lithium-ion batteries

    International Nuclear Information System (INIS)

    Wu, Mao-Sung; Lin, Ya-Ping

    2011-01-01

    A nickel-oxide film with monodispersed open macropores was prepared on a stainless-steel substrate by electrophoretic deposition of a polystyrene-sphere monolayer followed by anodic electrodeposition of nickel oxy-hydroxide. The deposited films convert to cubic nickel oxide after annealing at 400 o C for 1 h. Galvanostatic charge and discharge results indicate that the nickel-oxide film with monodispersed open macropores is capable of delivering a higher capacity than the bare nickel-oxide film, especially in high-rate charge and discharge processes. The lithiation capacity of macroporous nickel oxide reaches 1620 mA h g -1 at 1 C current discharge and decreases to 990 mA h g -1 at 15 C current discharge. The presence of monodispersed open macropores in the nickel-oxide film might facilitate the electrolyte penetration, diffusion, and migration. Electrochemical reactions between nickel oxide and lithium ions are therefore markedly improved by this tailored film architecture.

  5. Characterization of Monodispersed Iron Oxide Nanocrystals by XAS and MCD measurement

    International Nuclear Information System (INIS)

    Kim, J.-Y.; Noh, H.-J.; Park, B.-G.; Kim, T.-Y.; Park, J.-H.; Hyeon, T.; Park, J.; Kang, E.

    2004-01-01

    Full text: Nanoparticles have attracted so much attention because of their potential technological applications and abundance of scientifically interesting issues. In particular, magnetic nanoparticles are considered to be applicable to various magnetic devices such as terabit memory, ferrofluids, magnetocaloric refrigeration systems, blood cells, etc. With the development of nano-technology, variation of physical properties as a function of particle size is one of the most important issues, but has been rarely explored because of difficulty of the size control in synthesizing nanoparticles. Recently, some of us successfully synthesized high crystalline and monodisperse maghemite nanoparticles without a size selection process and research in this field seems to be promoted by one step. In this report, we present a systematic characterization of the monodispersed nanocrystalline γ - Fe 2 O 3 with the diameter of 13, 8 and 4 nm by measuring the x-ray absorption spectroscopy (XAS) and the x-ray magnetic circular dichroism(XMCD) spectra on Fe L edge. The spectra of the 4 nm nanoparticles are very similar to those of maghemite (γ - Fe 2 O 3 ). However, the spectra become close to those of magnetite (Fe 3 O 4 ) as the particle size becomes 8 and 13 nm. Considering that the maghemite and magnetite have the same spinel structure with different Fe vacancies, these results can be explained that the surface of nanoparticles has more vacancies than the core part, indicating that surface disorder increases as the particle size decreases

  6. An alternative route towards monodisperse CdS quantum dots for hybrid solar cells

    International Nuclear Information System (INIS)

    Cao, Fengfeng; Wang, Hao; Xia, Zhouhui; Dai, Xiao; Cong, Shan; Dong, Chao; Sun, Baoquan; Lou, Yanhui; Sun, Yinghui; Zhao, Jie; Zou, Guifu

    2015-01-01

    Monodisperse CdS quantum dots (QDs) are synthesized by thermal decomposition of organic complexes in the system of the cost-effective commercial 0 # diesel at 200 °C. The prepared CdS QDs have a good dispersion and high crystallization. When the CdS QDs are doped into the blends of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6, 6)C61 (PCBM) for hybrid solar cells (HSCs), the HSCs achieve about 25% increase of power conversion efficiency in comparison to the reference device without the CdS QDs. The improvement of the cell performance mainly attributes to the increased short-circuit current density arising from the absorption enhancement in the wavelength range of 350–550 nm by introducing the synthesized CdS QDs into the P3HT: PCBM active layer. - Highlights: • Monodisperse CdS quantum dots. • A cost-effective route to synthesize crystalline CdS quantum dots. • CdS quantum dots based hybrid solar cells with power conversion efficiency enhancement

  7. An alternative route towards monodisperse CdS quantum dots for hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Fengfeng; Wang, Hao [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Xia, Zhouhui [Institute of Functional Nano and Soft Materials, Soochow University, Suzhou 215123 (China); Dai, Xiao; Cong, Shan [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Dong, Chao [Department of Chemistry and Biology, University of New Mexico, ABQ 87120 (United States); Sun, Baoquan [Institute of Functional Nano and Soft Materials, Soochow University, Suzhou 215123 (China); Lou, Yanhui, E-mail: yhlou@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Sun, Yinghui; Zhao, Jie [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Zou, Guifu, E-mail: zouguifu@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China)

    2015-01-15

    Monodisperse CdS quantum dots (QDs) are synthesized by thermal decomposition of organic complexes in the system of the cost-effective commercial 0{sup #} diesel at 200 °C. The prepared CdS QDs have a good dispersion and high crystallization. When the CdS QDs are doped into the blends of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6, 6)C61 (PCBM) for hybrid solar cells (HSCs), the HSCs achieve about 25% increase of power conversion efficiency in comparison to the reference device without the CdS QDs. The improvement of the cell performance mainly attributes to the increased short-circuit current density arising from the absorption enhancement in the wavelength range of 350–550 nm by introducing the synthesized CdS QDs into the P3HT: PCBM active layer. - Highlights: • Monodisperse CdS quantum dots. • A cost-effective route to synthesize crystalline CdS quantum dots. • CdS quantum dots based hybrid solar cells with power conversion efficiency enhancement.

  8. Growth of monodisperse mesoscopic metal-oxide colloids under constant monomer supply

    Science.gov (United States)

    Nozawa, Koh; Delville, Marie-Hélène; Ushiki, Hideharu; Panizza, Pascal; Delville, Jean-Pierre

    2005-07-01

    In closed systems, control over the size of monodisperse metal-oxide colloids is generally limited to submicrometric dimensions. To overcome this difficulty, we explore the formation and growth of silica particles under constant monomer supply. The monomer source is externally driven by the progressive addition into the system of one of the precursors. Monodisperse spherical particles are produced up to a mesoscopic size. We analyze their growth versus the monomer addition rate at different temperatures. Our results show that in the presence of a continuous monomer addition, growth is limited by diffusion over the investigated temporal window. Using the temperature variation of the growth rate, we prove that rescaling leads to a data reduction onto a single master curve. Contrary to the growth process, the final particle’s size reached after the end of the reagent supply strongly depends on the addition rate. The variation of the final particle size versus addition rate can be deduced from an analogy with crystal formation in jet precipitation. Within this framework, and using the temperature dependences of both the particle growth law and the final size, we determine the value of the molecular heat of dissolution associated to the silica solubility. These observations support the fact that classical theories of phase-ordering dynamics can be extended to the synthesis of inorganic particles. The emergence of a master behavior in the presence of continuous monomer addition also suggests the extension of these theories to open systems.

  9. Facile Synthesis of Mono-Dispersed Polystyrene (PS/Ag Composite Microspheres via Modified Chemical Reduction

    Directory of Open Access Journals (Sweden)

    Wen Zhu

    2013-12-01

    Full Text Available A modified method based on in situ chemical reduction was developed to prepare mono-dispersed polystyrene/silver (PS/Ag composite microspheres. In this approach; mono-dispersed PS microspheres were synthesized through dispersion polymerization using poly-vinylpyrrolidone (PVP as a dispersant at first. Then, poly-dopamine (PDA was fabricated to functionally modify the surfaces of PS microspheres. With the addition of [Ag(NH32]+ to the PS dispersion, [Ag(NH32]+ complex ions were absorbed and reduced to silver nanoparticles on the surfaces of PS-PDA microspheres to form PS/Ag composite microspheres. PVP acted both as a solvent of the metallic precursor and as a reducing agent. PDA also acted both as a chemical protocol to immobilize the silver nanoparticles at the PS surface and as a reducing agent. Therefore, no additional reducing agents were needed. The resulting composite microspheres were characterized by TEM, field emission scanning electron microscopy (FESEM, energy-dispersive X-ray spectroscopy (EDS, XRD, UV-Vis and surface-enhanced Raman spectroscopy (SERS. The results showed that Ag nanoparticles (NPs were homogeneously immobilized onto the PS microspheres’ surface in the presence of PDA and PVP. PS/Ag composite microspheres were well formed with a uniform and compact shell layer and were adjustable in terms of their optical property.

  10. Lock and Key Colloids through Polymerization-Induced Buckling of Monodispersed Silicon Oil Droplets

    Science.gov (United States)

    Sacanna, Stefano; Irvine, William T. M.; Chaikin, Paul M.; Pine, David J.

    2010-03-01

    Colloidal particles can spontaneously associate into larger structured aggregates when driven by selective and directional interactions. Colloidal organization can be programmed by engineering shapes and interactions of basic building blocks in a manner similar to molecular self-assembly. Examples of successful strategies that allow non-trivial assembly of particles include template-directed patterning, capillary forces and, most commonly, the functionalization of the particle surfaces with ``sticky patches'' of biological or synthetic molecules. The level of complexity of the realizable assemblies, increases when particles with well defined shape anisotropies are used. In particular depletion forces and specific surface treatments in combination with non spherical particles have proven to be powerful tools to self-assembly complex microstructures. We describe a simple, high yield, synthetic pathway to fabricate monodisperse hybrid silica spheres with well defined cavities. Because the particle morphologies are reproducible and tunable with precision, the resulting particles can be used as basic building blocks in the assembly of larger monodisperse clusters. This is demonstrated using depletion to drive the self-assembly.

  11. Microwave Synthesized Monodisperse CdS Spheres of Different Size and Color for Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Carlos A. Rodríguez-Castañeda

    2015-01-01

    Full Text Available Monodisperse CdS spheres of size of 40 to 140 nm were obtained by microwave heating from basic solutions. It is observed that larger CdS spheres were formed at lower solution pH (8.4–8.8 and smaller ones at higher solution pH (10.8–11.3. The color of CdS products changed with solution pH and reaction temperature; those synthesized at lower pH and temperature were of green-yellow color, whereas those formed at higher pH and temperature were of orange-yellow color. A good photovoltage was observed in CdS:poly(3-hexylthiophene solar cells with spherical CdS particles. This is due to the good dispersion of CdS nanoparticles in P3HT solution that led to a large interface area between the organic and inorganic semiconductors. Higher photocurrent density was obtained in green-yellow CdS particles of lower defect density. The efficient microwave chemistry accelerated the hydrolysis of thiourea in pH lower than 9 and produced monodisperse spherical CdS nanoparticles suitable for solar cell applications.

  12. Linear theory on temporal instability of megahertz faraday waves for monodisperse microdroplet ejection.

    Science.gov (United States)

    Tsai, Shirley C; Tsai, Chen S

    2013-08-01

    A linear theory on temporal instability of megahertz Faraday waves for monodisperse microdroplet ejection based on mass conservation and linearized Navier-Stokes equations is presented using the most recently observed micrometer- sized droplet ejection from a millimeter-sized spherical water ball as a specific example. The theory is verified in the experiments utilizing silicon-based multiple-Fourier horn ultrasonic nozzles at megahertz frequency to facilitate temporal instability of the Faraday waves. Specifically, the linear theory not only correctly predicted the Faraday wave frequency and onset threshold of Faraday instability, the effect of viscosity, the dynamics of droplet ejection, but also established the first theoretical formula for the size of the ejected droplets, namely, the droplet diameter equals four-tenths of the Faraday wavelength involved. The high rate of increase in Faraday wave amplitude at megahertz drive frequency subsequent to onset threshold, together with enhanced excitation displacement on the nozzle end face, facilitated by the megahertz multiple Fourier horns in resonance, led to high-rate ejection of micrometer- sized monodisperse droplets (>10(7) droplets/s) at low electrical drive power (<;1 W) with short initiation time (<;0.05 s). This is in stark contrast to the Rayleigh-Plateau instability of a liquid jet, which ejects one droplet at a time. The measured diameters of the droplets ranging from 2.2 to 4.6 μm at 2 to 1 MHz drive frequency fall within the optimum particle size range for pulmonary drug delivery.

  13. Fractional vector calculus for fractional advection dispersion

    Science.gov (United States)

    Meerschaert, Mark M.; Mortensen, Jeff; Wheatcraft, Stephen W.

    2006-07-01

    We develop the basic tools of fractional vector calculus including a fractional derivative version of the gradient, divergence, and curl, and a fractional divergence theorem and Stokes theorem. These basic tools are then applied to provide a physical explanation for the fractional advection-dispersion equation for flow in heterogeneous porous media.

  14. Dynamics of polyelectrolyte adsorption and colloidal flocculation upon mixing studied using mono-dispersed polystyrene latex particles

    NARCIS (Netherlands)

    Feng, Lili; Cohen Stuart, Martien; Adachi, Yasuhisa

    2015-01-01

    The dynamic behavior of polyelectrolytes just after their encounter with the surface of bare colloidal particles is analyzed, using the flocculation properties of mono-dispersed polystyrene latex (PSL) particles. Applying a Standardized Colloid Mixing (SCM) approach, effects of ionic strength and

  15. Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

    KAUST Repository

    Chng, Ting Ting; Polavarapu, Lakshminarayana; Xu, Qing Hua; Ji, Wei; Zeng, Hua Chun

    2011-01-01

    Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse Aux

  16. Plasma-assisted synthesis of monodispersed and robust Ruthenium ultrafine nanocatalysts for organosilane oxidation and oxygen evolution reactions

    NARCIS (Netherlands)

    Gnanakumar, E.S.; Ng, W.; Filiz, B.C.; Rothenberg, G.; Wang, S.; Xu, H.; Pastor-Pérez, L.; Pastor-Blas, M.M.; Sepúlveda-Escribano, A.; Yan, N.; Shiju, N.R.

    2017-01-01

    We report a facile and general approach for preparing ultrafine ruthenium nanocatalysts by using a plasma-assisted synthesis at <100 °C. The resulting Ru nanoparticles are monodispersed (typical size 2 nm) and remain that way upon loading onto carbon and TiO2 supports. This gives robust catalysts

  17. Principles of transverse flow fractionation of microparticles in superhydrophobic channels.

    Science.gov (United States)

    Asmolov, Evgeny S; Dubov, Alexander L; Nizkaya, Tatiana V; Kuehne, Alexander J C; Vinogradova, Olga I

    2015-07-07

    We propose a concept of fractionation of micron-sized particles in a microfluidic device with a bottom wall decorated by superhydrophobic stripes. The stripes are oriented at an angle α to the direction of a driving force, G, which generally includes an applied pressure gradient and gravity. Separation relies on the initial sedimentation of particles under gravity in the main forward flow, and their subsequent lateral deflection near a superhydrophobic wall due to generation of a secondary flow transverse to G. We provide some theoretical arguments allowing us to quantify the transverse displacement of particles in the microfluidic channel, and confirm the validity of theoretical predictions in test experiments with monodisperse fractions of microparticles. Our results can guide the design of superhydrophobic microfluidic devices for efficient sorting of microparticles with a relatively small difference in size and density.

  18. Fractional Schroedinger equation

    International Nuclear Information System (INIS)

    Laskin, Nick

    2002-01-01

    Some properties of the fractional Schroedinger equation are studied. We prove the Hermiticity of the fractional Hamilton operator and establish the parity conservation law for fractional quantum mechanics. As physical applications of the fractional Schroedinger equation we find the energy spectra of a hydrogenlike atom (fractional 'Bohr atom') and of a fractional oscillator in the semiclassical approximation. An equation for the fractional probability current density is developed and discussed. We also discuss the relationships between the fractional and standard Schroedinger equations

  19. DNA-imprinted polymer nanoparticles with monodispersity and prescribed DNA-strand patterns

    Science.gov (United States)

    Trinh, Tuan; Liao, Chenyi; Toader, Violeta; Barłóg, Maciej; Bazzi, Hassan S.; Li, Jianing; Sleiman, Hanadi F.

    2018-02-01

    As colloidal self-assembly increasingly approaches the complexity of natural systems, an ongoing challenge is to generate non-centrosymmetric structures. For example, patchy, Janus or living crystallization particles have significantly advanced the area of polymer assembly. It has remained difficult, however, to devise polymer particles that associate in a directional manner, with controlled valency and recognition motifs. Here, we present a method to transfer DNA patterns from a DNA cage to a polymeric nanoparticle encapsulated inside the cage in three dimensions. The resulting DNA-imprinted particles (DIPs), which are 'moulded' on the inside of the DNA cage, consist of a monodisperse crosslinked polymer core with a predetermined pattern of different DNA strands covalently 'printed' on their exterior, and further assemble with programmability and directionality. The number, orientation and sequence of DNA strands grafted onto the polymeric core can be controlled during the process, and the strands are addressable independently of each other.

  20. Nonthermal plasma synthesis of size-controlled, monodisperse, freestanding germanium nanocrystals

    International Nuclear Information System (INIS)

    Gresback, Ryan; Holman, Zachary; Kortshagen, Uwe

    2007-01-01

    Germanium nanocrystals may be of interest for a variety of electronic and optoelectronic applications including photovoltaics, primarily due to the tunability of their band gap from the infrared into the visible range of the spectrum. This letter discusses the synthesis of monodisperse germanium nanocrystals via a nonthermal plasma approach which allows for precise control of the nanocrystal size. Germanium crystals are synthesized from germanium tetrachloride and hydrogen entrained in an argon background gas. The crystal size can be varied between 4 and 50 nm by changing the residence times of crystals in the plasma between ∼30 and 440 ms. Adjusting the plasma power enables one to synthesize fully amorphous or fully crystalline particles with otherwise similar properties

  1. Monodisperse, submicrometer-scale platinum colloidal spheres with high electrocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lixue; Wang, Liang; Guo, Shaojun; Zhai, Junfeng; Dong, Shaojun; Wang, Erkang [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, 130022 Jilin, Changchun (China)

    2009-02-15

    Monodisperse, submicrometer-scale platinum (Pt) colloidal spheres were prepared through a simple direct chemical reduction of p-phenylenediamine (PPD)-chloroplatinic acid (H{sub 2}PtCl{sub 6}) coordination polymer colloids. It was found that the prepared Pt colloids had the similar size and morphology with their coordination polymer precursors, and the prepared Pt colloids with rough surfaces were three-dimensional (3D) structured assemblies of high-density small Pt nanoparticles. The electrochemical experiments confirmed that the prepared Pt colloids possessed a high electrocatalytic activity towards mainly four-electron reduction of dioxygen to water, making the prepared Pt colloids potential candidates for the efficient cathode material in fuel cells. (author)

  2. Synthesis of Monodisperse Walnut-Like SnO2 Spheres and Their Photocatalytic Performances

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2015-01-01

    Full Text Available Novel walnut-like SnO2 spheres have been synthesized using a one-step hydrothermal reaction with SnCl2·2H2O and KOH as raw materials. The morphology, microstructure, and optical properties of the products were characterized by X-ray powder diffraction (XRD, Raman spectrum, scanning electron microscopy (SEM, transmission electron microscopy (TEM, selected area electron diffraction (SAED, and ultraviolet-visible (UV-Vis absorption spectroscopy. The detailed studies revealed that these synthesized spheres are highly monodisperse and have a uniform size of approximately 250 nm. Photocatalytic activity of the prepared SnO2 spheres was evaluated by the degradation of methylene orange. The synthesized SnO2 spheres exhibited excellent photocatalytic degradation. In addition, a possible formation mechanism of the walnut-like nanostructures was proposed based on reaction time-dependent experiments.

  3. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity

    Science.gov (United States)

    Bindhu, M. R.; Umadevi, M.

    2013-01-01

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

  4. Monodispersed ZIF-8 particles with enhanced performance for CO2 adsorption and heterogeneous catalysis

    Science.gov (United States)

    Guan, Yebin; Shi, Juanjuan; Xia, Ming; Zhang, Jun; Pang, Zhenfeng; Marchetti, Alessandro; Wang, Xiaohong; Cai, Jingsong; Kong, Xueqian

    2017-11-01

    Monodispersed zeolitic imidazolate frameworks (ZIFs) were prepared with a simple method using dimethylsulfoxide (DMSO) as solvent. This method yields ZIF-8 nanoparticles with a narrow particle size distribution of 90-110 nm and the dispersion is highly stable against agglomeration. These particles have larger nanosized porosity and enhanced CO2 adsorption capability compared to ZIF-8 prepared with different solvents such as methanol or N, N-dimethyl formamide. Their uniform size and surface chemistry also lead to superior performance in the Knoevenagel condensation reactions. The ZIF-8 nanoparticles possess high thermal stability up to 550 °C and the preparation steps are easy for scaling up which are favorable for industrial applications.

  5. Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

    International Nuclear Information System (INIS)

    Ghosh, Swapankumar; Divya, Damodaran; Remani, Kottayilpadi C.; Sreeremya, Thadathil S.

    2010-01-01

    Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 o C. The activation energy for growth of CeO 2 nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO 2 particles in narrow size range. CeO 2 nanocrystals precipitated at 35 o C were further annealed at temperatures in the range 300-700 o C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

  6. Microwave Synthesis of Nearly Monodisperse Core/Multishell Quantum Dots with Cell Imaging Applications

    Directory of Open Access Journals (Sweden)

    Xu Hengyi

    2010-01-01

    Full Text Available Abstract We report in this article the microwave synthesis of relatively monodisperse, highly crystalline CdSe quantum dots (QDs overcoated with Cd0.5Zn0.5S/ZnS multishells. The as-prepared QDs exhibited narrow photoluminescence bandwidth as the consequence of homogeneous size distribution and uniform crystallinity, which was confirmed by transmission electron microscopy. A high photoluminescence quantum yield up to 80% was measured for the core/multishell nanocrystals. Finally, the resulting CdSe/Cd0.5Zn0.5S/ZnS core/multishell QDs have been successfully applied to the labeling and imaging of breast cancer cells (SK-BR3.

  7. A novel approach for preparation of micrometer-sized, monodisperse dimple and hemispherical polystyrene particles.

    Science.gov (United States)

    Tanaka, Takuya; Komatsu, Yoshifumi; Fujibayashi, Teruhisa; Minami, Hideto; Okubo, Masayoshi

    2010-03-16

    Micrometer-sized, monodisperse dimple and hemispherical polystyrene (PS) particles were successfully prepared by heating (55-70 degrees C) of spherical PS particles dispersed in methanol/water media (40/60 to 80/20, w/w) in the presence of decane droplets, and subsequent cooling down to room temperature. Decane was absorbed by the PS particles during the heating process. Decane-absorbed PS particles phase-separated into PS and decane phases in the inside during the cooling process, and eventually dimple and/or hemispherical particles were formed by removal of the decane phase from phase-separated PS/decane particles by evaporation. The size of the dimple, which is determined by the volume of decane phase-separated from decane-absorbed PS particles during the cooling process, increased with increases in the heating temperature and the methanol content.

  8. Measurement and interpretation of growth and evaporation of monodispersed droplets in a shock tube

    Science.gov (United States)

    Peters, F.; Paikert, B.

    1994-01-01

    A special gasdynamic shock tube process in combination with a Mie light scattering method is used to study growth and subsequent evaporation of monodispersed droplets carried in argon or air. The droplets are generated by homogeneous nucleation and observed in the micrometer range (0.15-6 micrometer radius). Droplet concentrations range from 10-1000/cu mm. Four different substances, i.e. water, n-propanol, methanol and n-hexane are tested for a wide range of properties. A model covering the entire range between large (Kn much greater than 1) and small Knudsen numbers (K much less than 1) is applied to interpret the experimental data. Excellent agreement is found.

  9. Extracellular biosynthesis of monodispersed gold nanoparticles by a SAM capping route

    Science.gov (United States)

    Wen, Li; Lin, Zhonghua; Gu, Pingying; Zhou, Jianzhang; Yao, Bingxing; Chen, Guoliang; Fu, Jinkun

    2009-02-01

    Monodispersed gold nanoparticles capped with a self-assembled monolayer of dodecanethiol were biosynthesized extracellularly by an efficient, simple, and environmental friendly procedure, which involved the use of Bacillus megatherium D01 as the reducing agent and the use of dodecanethiol as the capping ligand at 26 °C. The kinetics of gold nanoparticle formation was followed by transmission electron microscope (TEM) and UV-vis spectroscopy. It was shown that reaction time was an important parameter in controlling the morphology of gold nanoparticles. The effect of thiol on the shape, size, and dispersity of gold nanoparticles was also studied. The results showed that the presence of thiol during the biosynthesis could induce the formation of small size gold nanoparticles (gold nanoparticles capped with thiol of 1.9 ± 0.8 nm size were formed by using Bacillus megatherium D01.

  10. Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.

    Science.gov (United States)

    Bindhu, M R; Umadevi, M

    2013-01-15

    Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Production and characterization of monodisperse uranium particles for nuclear safeguards applications

    International Nuclear Information System (INIS)

    Knott, Alexander

    2016-01-01

    Environmental sampling is a very effective measure to detect undeclared nuclear activities. Generally, samples are taken as swipe samples on cotton. These swipes contain minute quantities of particulates which have an inherent signature of their production and release scenario. These inspection samples are assessed for their morphology, elemental composition and their isotopic vectors. Mass spectrometry plays a crucial role in determining the isotopic ratios of uranium. Method validation and instrument calibration with well-characterized quality control (QC)-materials, reference materials (RMs) and certified reference materials (CRMs) ensures reliable data output. Currently, the availability of suitable well defined microparticles containing uranium and plutonium reference materials is very limited. Primarily, metals, oxides and various uranium and plutonium containing solutions are commercially available. Therefore, the IAEA's Safeguards Analytical Services (SGAS) cooperates with the Institute of Nuclear Waste Management and Reactor Safety (IEK-6) at the Forschungszentrum Juelich GmbH in a joint task entitled ''Production of Particle Reference Materials''. The work presented in this thesis has been partially funded by the IAEA, Forschungszentrum Juelich GmbH and the Federal Ministry of Economic Affairs and Energy (BMWi) through the ''Joint Program on the Technical Development and Further Improvement of IAEA Safeguards between the Government of the Federal Republic of Germany and the IAEA''. The first step towards monodisperse microparticles was the development of pure uranium oxide particles made from certified reference materials. The focus of the dissertation is (1) the implementation of a working setup to produce monodisperse uranium oxide particles and (2) the characterization of these particles towards the application as QC-material. Monodisperse uranium oxide particles were produced by spray pyrolysis. It was demonstrated that the particle size can be

  12. One-pot template-free synthesis of monodisperse hollow hydrogel microspheres and their resulting properties.

    Science.gov (United States)

    Lim, Hyung-Seok; Kwon, Eunji; Lee, Moonjoo; Moo Lee, Young; Suh, Kyung-Do

    2013-08-01

    Monodisperse poly(methacrylic acid/ethyleneglycoldimethacrylate) (MAA/EGDMA) hollow microcapsules, which exhibit pH-responsive behavior, are prepared by diffusion of cationic surfactants and hydrophobic interaction. During the association of the negatively charged hydrogel microspheres and an oppositely charged surfactant (cetyltrimethylammonium bromide, CTA(+)B), the hydrophobic polymer-surfactant complexes that form are separated from the internal water; consequently, a hollow structure can be formed. Confocal laser scanning microscopy, UV spectro-scopy and zeta potential are employed to study the formation of the hollow structure during the diffusion of the cationic surfactant. The controlled release behavior of methylene blue as a model drug from the as-prepared poly(MAA/EGDMA) microcapsules with a hollow structure is investigated under different pH conditions. The hollow structure can be retained, even during repetitive pH changes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. A Convenient and Templated Method for the Fabrication of Monodisperse Micrometer Hollow Titania Spheres

    Directory of Open Access Journals (Sweden)

    Haibo Yao

    2013-01-01

    Full Text Available A simple and widely applicable methodology was presented to synthesize monodisperse micrometer hollow titania spheres (HTS based on the templating method. It was performed by using the preformed poly(styrene-acrylic acid (PSA as template spheres which was mixed with tetrabutyltitanate (TBOT in an ethanol solvent under steam treatment. The HTS which were obtained by the calcination of PSA/TiO2 composite core-shell spheres had a narrow particle size distribution and commendable surface topography characterized by SEM. The calcined HTS at 500°C displayed crystalline reflection peaks that were characteristic to the anatase phase by XRD. Moreover, some key influencing factors including TBOT concentration and reaction time were analyzed. As expected, the diameter of HTS could be readily controlled by altering the size of PSA template spheres. In addition, the approach was also applied to fabricate hollow zirconia spheres and other inorganic spheres.

  14. Parameterizing the competition between homogeneous and heterogeneous freezing in cirrus cloud formation – monodisperse ice nuclei

    Directory of Open Access Journals (Sweden)

    D. Barahona

    2009-01-01

    Full Text Available We present a parameterization of cirrus cloud formation that computes the ice crystal number and size distribution under the presence of homogeneous and heterogeneous freezing. The parameterization is very simple to apply and is derived from the analytical solution of the cloud parcel equations, assuming that the ice nuclei population is monodisperse and chemically homogeneous. In addition to the ice distribution, an analytical expression is provided for the limiting ice nuclei number concentration that suppresses ice formation from homogeneous freezing. The parameterization is evaluated against a detailed numerical parcel model, and reproduces numerical simulations over a wide range of conditions with an average error of 6±33%. The parameterization also compares favorably against other formulations that require some form of numerical integration.

  15. XAFS studies of monodisperse Au nanoclusters formation in the etching process

    International Nuclear Information System (INIS)

    Yang, Lina; Huang, Ting; Liu, Wei; Bao, Jie; Huang, Yuanyuan; Cao, Yuanjie; Yao, Tao; Sun, Zhihu; Wei, Shiqiang

    2016-01-01

    Understanding the formation mechanism of gold nanoclusters is essential to the development of their synthetic chemistry. Here, by using x-ray absorption fine-structure (XAFS) spectroscopy, UV-Vis and MS spectra, the formation process of monodisperse Au 13 nanoclusters is investigated. We find that a critical step involving the formation of smaller Au 8 -Au 11 metastable intermediate clusters induced by the HCl + HSR etching of the polydisperse Au n precursor clusters occurs firstly. Then these intermediate species undergo a size-growth to Au 13 cores, followed by a slow structure rearrangement to reach the final stable structure. This work enriches the understanding of cluster formation chemistry and may guide the way towards the design and the controllable synthesis of nanoclusters. (paper)

  16. Straightforward and robust synthesis of monodisperse surface-functionalized gold nanoclusters

    Directory of Open Access Journals (Sweden)

    Silvia Varela-Aramburu

    2016-09-01

    Full Text Available Gold nanoclusters are small (1–3 nm nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold nanoclusters using thioglucose as a reducing and stabilizing agent, which was discovered by serendipity. The resultant monodisperse gold nanoclusters are more stable than those generated using some other common methods. The carboxylic acid contained in the stabilizing agent on the cluster surface serves as anchor for nanocluster functionalization. Alternatively, the addition of thiols serves to functionalize the nanoclusters. The resulting non-cytotoxic nanoclusters are taken up by cells and constitute a tuneable platform for biomedical applications including drug delivery.

  17. Experimental mixture design as a tool for the synthesis of antimicrobial selective molecularly imprinted monodisperse microbeads.

    Science.gov (United States)

    Benito-Peña, Elena; Navarro-Villoslada, Fernando; Carrasco, Sergio; Jockusch, Steffen; Ottaviani, M Francesca; Moreno-Bondi, Maria C

    2015-05-27

    The effect of the cross-linker on the shape and size of molecular imprinted polymer (MIP) beads prepared by precipitation polymerization has been evaluated using a chemometric approach. Molecularly imprinted microspheres for the selective recognition of fluoroquinolone antimicrobials were prepared in a one-step precipitation polymerization procedure using enrofloxacin (ENR) as the template molecule, methacrylic acid as functional monomer, 2-hydroxyethyl methacrylate as hydrophilic comonomer, and acetonitrile as the porogen. The type and amount of cross-linker, namely ethylene glycol dimethacrylate, divinylbenzene or trimethylolpropane trimethacrylate, to obtain monodispersed MIP spherical beads in the micrometer range was optimized using a simplex lattice design. Particle size and morphology were assessed by scanning electron microscopy, dynamic light scattering, and nitrogen adsorption measurements. Electron paramagnetic resonance spectroscopy in conjunction with a nitroxide as spin probe revealed information about the microviscosity and polarity of the binding sites in imprinted and nonimprinted polymer beads.

  18. Photoelectrochemical performance of DSSC with monodisperse and polydisperse ZnO SPs

    Energy Technology Data Exchange (ETDEWEB)

    Wahyuono, Ruri Agung, E-mail: r-agung-w@ep.its.ac.id; Risanti, Doty D., E-mail: r-agung-w@ep.its.ac.id [Department of Engineering Physics, Institut Teknologi Sepuluh Nopember (Indonesia); Shirosaki, Tomohiro; Nagaoka, Shoji [Kumamoto Industrial Research Institute (Japan); Takafuji, Makoto; Ihara, Hirotaka [Department of Applied Chemistry and Biochemistry, Kumamoto University (Japan)

    2014-02-24

    Zinc oxide, ZnO, is one of oxide semiconductors being used in DSSC. ZnO is promising material for having fairly higher energy band gap and much higher bulk electron mobility than that of anatase TiO{sub 2}, the most widely used semiconductor for DSSC photoelectrode. This study introduces the synthesis of ZnO by precipitation method. The synthesis involves ZnAc dihydrate and diethylene glycol (DEG) for the chemicals. Various size of ZnO spherical particles (SPs) are obtained in polydisperse and monodisperse particles. Monolayer and bilayer DSSCs are fabricated in sandwich structure and sensitized with N719 dye for 3 and 5 hours. Monolayer DSSC using monodisperse particles (422 nm) is able to generate highest conversion efficiency of 0.569% (V{sub oc} = 541.3 mV, J{sub sc} = 1.92 mA/cm{sup 2}, and fill factor of 54.78%). Bilayer DSSC, i.e. combined 422 - 185 nm ZnO layer, can optimize the photocurrent action spectra in UV regime leading to high conversion efficiency of 0.568 (V{sub oc} = 568.2 mV, J{sub sc} = 2.22 mA/cm{sup 2}, and fill factor of 47.25%). The longer sensitizing time does not always produce better conversion efficiency since it can induce the dissolution of Zn atoms and formation of Zn{sup 2+} - dye resisting the electron transport from dye to ZnO photoelectrode.

  19. Highly sensitive glucose sensor based on monodisperse palladium nickel/activated carbon nanocomposites.

    Science.gov (United States)

    Koskun, Yağmur; Şavk, Aysun; Şen, Betül; Şen, Fatih

    2018-06-20

    Glucose enzyme biosensors have been used for a variety of applications such as medical diagnosis, bioprocess engineering, beverage industry and environmental scanning etc. and there is still a growing interest in glucose sensors. For this purpose, addressed herein, as a novel glucose sensor, highly sensitive activated carbon (AC) decorated monodisperse nickel and palladium alloy nanocomposites modified glassy carbon electrode (Ni-Pd@AC/GCE NCs) have been synthesized by in-situ reduction technique. Raman Spectroscopy (RS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), cyclic voltammetry (CV) and chronoamperometry (CA) were used for the characterization of the prepared non-enzymatic glucose sensor. The characteristic sensor properties of the Ni-Pd@AC/GCE electrode were compared with Ni-Pd NCs/GCE, Ni@AC/GCE and Pd@AC/GCE and the results demonstrate that the AC is very effective in the enhancement of the electrocatalytic properties of sensor. In addition, the Ni-Pd@AC/GCE nanocomposites showed a very low detection limit of 0.014 μM, a wide linear range of 0.01 mM-1 mM and a very high sensitivity of 90 mA mM -1  cm -2 . Furthermore, the recommended sensor offer the various advantageous such as facile preparation, fast response time, high selectivity and sensitivity. Lastly, monodisperse Ni-Pd@AC/GCE was utilized to detect glucose in real sample species. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Production of monodispersed Oil-in Water Emulsion Using Crossflow-Type Silicon Microchannel Plate

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, Takahiro.; Komori, Hideaki.; Yonemoto, Toshikuni. [Tohoku University, Miyagi (Japan). Chemical Engineering Department; Nakajima, Mitsutoshi.; Kikuchi, Yuji. [National Food Research Institute, Ibaraki (Japan)

    1999-04-01

    A novel method for continuous productin of monodispersed oil-in-water (O/W) emulsion is developed using acrossflow-type silicaon microchannel plate. On the single crystal silicon plate, a liquid flow path for continuous phase was made, and at each side of th wall of the path an array of regular-sized slits was precisely fabricated. A flat glass plate was tightly attached on the microchannel plate to cover the top of the slits to form the array of microchannels. Regular-sized oil (triolein) droplets were generated by squeezing the oil through the microchannels into the continuous-phase water (0.3 wt% sodium lauryl sulfate solutin) flowing in the liquid path. Oil droplet size is significantly dependent on the microchannel structure, which is identified with the microchannel width, height, and the length of the terrace (a flat area at the microchannel outlet). Three types of microchannel plates having different microchannel structures generate monodispersed emulsions of different average droplet sizes, 16,20, and 48 {mu}m at the watr flow rate of 1.4x10{sup -2}mL{center_dot}min{sup -1}. For the microchannel plate which generates large droplets of 48 {mu}m, increasing the flow rate causes decreasing droplet size. However, for the microchannel plate which generates small droplets of 16 or 20 {mu}m, the size is not affected by the flow rate within the range from 1.4x10{sup -2}to 2.4 mL{center_dot}min{sup -1}. In every case, the droplet size distribution is narrow, and the geometric standard deviation is 1.03 or less. (author)

  1. Controlled synthesis of monodisperse gold nanorods with different aspect ratios in the presence of aromatic additives

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Wang, Feihu [Shanghai Jiao Tong University, School of Pharmacy (China); Guo, Yuan [University of Leeds, School of Chemistry and Astbury Centre for Structural Molecular Biology (United Kingdom); Chen, Rongjun, E-mail: rongjun.chen@imperial.ac.uk [Imperial College London, Department of Chemical Engineering (United Kingdom); Shen, Yuanyuan; Guo, Aijie; Liu, Jieying; Zhang, Xiao [Shanghai Jiao Tong University, School of Pharmacy (China); Zhou, Dejian, E-mail: d.zhou@leeds.ac.uk [University of Leeds, School of Chemistry and Astbury Centre for Structural Molecular Biology (United Kingdom); Guo, Shengrong, E-mail: srguo@sjtu.edu.cn [Shanghai Jiao Tong University, School of Pharmacy (China)

    2014-12-15

    This paper reports the synthesis of monodisperse gold nanorods (GNRs) via a simple seeded growth approach in the presence of different aromatic additives, such as 7-bromo-3-hydroxy-2-naphthoic acid (7-BrHNA), 3-hydroxy-2-naphthoic acid (HNA), 5-bromosalicylic acid (5-BrSA), salicylic acid (SA), or phenol (PhOH). Effects of the aromatic additives and hydrochloric acid (HCl) on the structure and optical properties of the synthesized GNRs were investigated. The longitudinal surface plasmon resonance (LSPR) peak wavelength of the resulting GNRs was found to be dependent on the aromatic additive in the following sequence: 5-BrSA (778 nm) > 7-BrHNA (706 nm) > SA (688 nm) > HNA (676 nm) > PhOH (638 nm) without the addition of HCl, but this was changed to 7-BrHNA (920 nm) > SA (890 nm) > HNA (872 nm) > PhOH (858 nm) > 5-BrSA (816 nm) or 7-BrHNA (1,005 nm) > PhOH (995 nm) > SA (990 nm) > HNA (980 nm) > 5-BrSA (815 nm) with the addition of HCl or HNO{sub 3}, respectively. The LSPR peak wavelength was increased with the increasing concentration of 7-BrHNA without HCl addition; however, there was a maximum LSPR peak wavelength when HCl was added. Interestingly, the LSPR peak wavelength was also increased with the amount of HCl added. The results presented here thus established a simple approach to synthesize monodisperse GNRs of different LSPR wavelengths.

  2. Meadow based Fraction Theory

    OpenAIRE

    Bergstra, Jan A.

    2015-01-01

    In the context of an involutive meadow a precise definition of fractions is formulated and on that basis formal definitions of various classes of fractions are given. The definitions follow the fractions as terms paradigm. That paradigm is compared with two competing paradigms for storytelling on fractions: fractions as values and fractions as pairs.

  3. Fermionic bound states in distinct kinklike backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, Paraiba (Brazil); Mohammadi, A. [Universidade Federal de Campina Grande, Departamento de Fisica, Caixa Postal 10071, Campina Grande, Paraiba (Brazil)

    2017-04-15

    This work deals with fermions in the background of distinct localized structures in the two-dimensional spacetime. Although the structures have a similar topological character, which is responsible for the appearance of fractionally charged excitations, we want to investigate how the geometric deformations that appear in the localized structures contribute to the change in the physical properties of the fermionic bound states. We investigate the two-kink and compact kinklike backgrounds, and we consider two distinct boson-fermion interactions, one motivated by supersymmetry and the other described by the standard Yukawa coupling. (orig.)

  4. Microfluidic Devices for Blood Fractionation

    OpenAIRE

    Hou, Han Wei; Bhagat, Ali Asgar S.; Lee, Wong Cheng J.; Huang, Sha; Han, Jongyoon; Lim, Chwee Teck

    2011-01-01

    Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. ...

  5. Xenon fractionation in porous planetesimals

    Science.gov (United States)

    Zahnle, Kevin; Pollack, James B.; Kasting, James F.

    1990-01-01

    The distinctively fractionated Xe on Mars and earth may have its root in a common source from which both planets accreted. Beginning with Ozima and Nakazawa's (1980) hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals, it is pointed out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. It is shown that enough fractionated Xe to supply the earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and Martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, the present hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula.

  6. Xenon fractionation in porous planetesimals

    International Nuclear Information System (INIS)

    Zahnle, K.; Pollack, J.B.; Kasting, J.F.

    1990-01-01

    The distinctively fractionated Xe on Mars and Earth may have its root in a common source from which both planets accreted. We begin with Ozima and Nakazawa's hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals. We point out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. We show that enough fractionated Xe to supply the Earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, our hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula. The required planetesimals are large, representing a class of object now extinct in the solar system

  7. Fractional Vector Calculus and Fractional Special Function

    OpenAIRE

    Li, Ming-Fan; Ren, Ji-Rong; Zhu, Tao

    2010-01-01

    Fractional vector calculus is discussed in the spherical coordinate framework. A variation of the Legendre equation and fractional Bessel equation are solved by series expansion and numerically. Finally, we generalize the hypergeometric functions.

  8. Metal Fe3+ ions assisted synthesis of highly monodisperse Ag/SiO2 nanohybrids and their antibacterial activity

    International Nuclear Information System (INIS)

    Zhang, Nianchun; Xue, Feng; Yu, Xiang; Zhou, Huihua; Ding, Enyong

    2013-01-01

    Graphical abstract: TEM images of the Ag/SiO 2 -2 nanohybrids. The homogeneous and more mono-disperse Ag nanoparticles deposit on SiO 2 spheres. Through this method, Ag nanoparticles are easily formed on the surface of SiO 2 compared to other methods. Highlights: ► We prepared homogeneous and mono-dispersed Ag/SiO 2 -2 nanohybrids by adding Fe 3+ ions. ► The Ag/SiO 2 -2 nanohybrids had core(SiO 2 )-shell(Ag) structure. ► The Ag/SiO 2 -2 nanohybrids exhibited excellent antibacterial activity against bacteria. ► The reaction temperature was lower and the yield of Ag/SiO 2 -2 nanohybrids were higher. - Abstract: Highly monodispersed Ag/SiO 2 nanohybrids with excellent antibacterial property were synthesized by using DMF as a reducing agent and employing an additional redox potential of metal Fe 3+ ion as a catalytic agent. The obtained Ag/SiO 2 -2 nanohybrids of about 240 nm were highly monodispersity and uniformity by adding trace Fe 3+ ions into the reaction which Ag + reacted with N,N-dimethyl formamide (DMF) at 70 °C. Compared to the conventional techniques, which need long time and high temperature for silica coating of Ag nanoparticles, this new method was capable of synthesizing monodispersed, uniform, high yield Ag/SiO 2 nanohybrids. The electron was transferred from the Fe 2+ ion to the Ag + ion to accelerate the nucleation of silver nanoparticles. The chemical structures, morphologies and properties of the Ag/SiO 2 nanohybrids were characterized by X-ray diffraction (XRD), (High-resolution, Scanning transmission) transmission electron microscopy (TEM, HRTEM and STEM), and X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy (UV–vis) and test of antibacterial. The results demonstrated that the silver nanoparticles supported on the surface of SiO 2 spheres in Ag/SiO 2 -2 nanohybrids structure, the Ag nanoparticles were homogeneous and monodispersed. The results also indicated that the Ag/SiO 2 -2 nanohybrid had excellent antibacterial.

  9. Tribological characteristics of monodispersed cerium borate nanospheres in biodegradable rapeseed oil lubricant

    Energy Technology Data Exchange (ETDEWEB)

    Boshui, Chen, E-mail: boshuichen@163.com; Kecheng, Gu; Jianhua, Fang; Jiang, Wu; Jiu, Wang; Nan, Zhang

    2015-10-30

    Graphical abstract: - Highlights: • Monodispersed stearic acid-capped cerium borate composite nanoparticles were prepared by hydrothermal method. Their morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics were also characterized. • The surface-capped cerium borate nanoparticles exhibited excellent dispersing stability in rapeseed oil. As new lubricating additives, they were also outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil in biodegradable rapeseed oil. The results presented in this paper would be of important significance for developing green lubricants and lubricant additives. • The prominent tribological performances of SA/CeBO{sub 3} in rapeseed oil were investigated and attributed to the formation of a composite boundary lubrication film mainly composed of lubricous tribochemical species on the tribo-surfaces. - Abstract: Stearic acid-capped cerium borate composite nanoparticles, abbreviated as SA/CeBO{sub 3}, were prepared by hydrothermal method. The morphologies, element compositions, size distributions, crystal and chemical structures, hydrophobic characteristics, of SA/CeBO{sub 3} were characterized by scanning electron microscope, energy dispersive X-ray spectrometer, dynamic laser particle size analyzer, X-ray diffraction, and Fourier transform infrared spectrometer, respectively. The friction and wear performances of SA/CeBO{sub 3} as a lubricating additive in a rapeseed oil were evaluated on a four-ball tribo-tester. The tribochemical characteristics of the worn surfaces were investigated by X-ray photoelectron spectroscopy. The results showed that the hydrophobic SA/CeBO{sub 3} were monodispersed nanospheres with an average diameter of 8 nm, and exhibited excellent dispersing stability in rapeseed oil. Meanwhile, SA/CeBO{sub 3} nanospheres were outstanding in enhancing friction-reducing and anti-wear capacities of rapeseed oil. The prominent

  10. Synthesis and optoelectronic properties of a monodispersed macrocycle oligomer consisting of three triarylamine units

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Qinggang, E-mail: gangq0172@163.com [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, College of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Pukou District, Nanjing 210044 (China); Qian, Haiyan, E-mail: qianhaiy@163.com [College of Material Science and Technology, Nanjing University of Technology, 5 Xinmofan Road, Nanjing 210009 (China); Zhou, Yonghui; Li, Jun; Xiao, Huining [Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, College of Environmental Science and Engineering, Nanjing University of Information Science and Technology, 219 Ningliu Road, Pukou District, Nanjing 210044 (China)

    2012-08-15

    A monodispersed macrocyclic oligomer constructed by three triarylmine units ((TPAT){sub 3}) was designed and readily synthesized from the monomer of 3-(4 Prime -(phenyl(4 Double-Prime -methylphenyl)amino)-phenyl)pentan-3-ol (TPAT) by means of a simple Friedel-Crafts alkylation reaction. The structure of the resultant macrocycle was examined using FT-IR, NMR and MALDI-TOF mass spectroscopy. Compared with 1,10-bis(di-4-tolylaminophenyl) cyclohexane (TAPC) and tri-p-tolylamine (TTA), (TPAT){sub 3} possesses the three-dimensional chair conformation and the higher T{sub g}. In the photoluminescence (PL) spectrum of (TPAT){sub 3} film, there are no excimer emission peaks in the range of 400-550 nm region as those of TAPC and TTA. Besides an EL peak at 386 nm, the single-layer device occured only the 438 nm excimer emission peak, whose intensity increased with the excitation voltage increase. Using 1,3,5-Tris(N-phenylbenzimidazol-2-yl)-benzene (TPBI) as the electron-transporting layer, the resulting double-layer device ITO/(TPAT){sub 3} (40 nm)/TPBI (40 nm)/Mg:Ag (10:1; 50 nm)/Ag (100 nm) only exhibited a 438 nm maximum symmetrical emission peak under an excitation voltage of 14 V. However, as the applied voltage was increased from 14 V to 19 V, the intensity of the symmetrical curve with a 468 nm peak from exciplex emission gets stronger and stronger. In fact, the resultant emission curve was asymmetrical, due to the overlap of two symmetrical curves with 438 nm and 468 nm peaks, respectively. The maximum luminance and luminous efficiency are 2240 cd m{sup -2} at 18.8 V and 1.73 cd A{sup -1} at 1878 cd m{sup -2} (13.9 V). Highlights: Black-Right-Pointing-Pointer The monodispersed macrocyclic oligomer constructed by three triarylamine units was synthesized and characterized. Black-Right-Pointing-Pointer The PL of (TPAT){sub 3} film does not emerge TAPC and TTA's emission peaks of over 400 nm region. Black-Right-Pointing-Pointer The 438 nm emission peak was found from

  11. Preparation and characterization of monodisperse large-porous silica microspheres as the matrix for protein separation.

    Science.gov (United States)

    Xia, Hongjun; Wan, Guangping; Zhao, Junlong; Liu, Jiawei; Bai, Quan

    2016-11-04

    High performance liquid chromatography (HPLC) is a kind of efficient separation technology and has been used widely in many fields. Micro-sized porous silica microspheres as the most popular matrix have been used for fast separation and analysis in HPLC. In this paper, the monodisperse large-porous silica microspheres with controllable size and structure were successfully synthesized with polymer microspheres as the templates and characterized. First, the poly(glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres (P GMA-EDMA ) were functionalized with tetraethylenepentamine (TEPA) to generate amino groups which act as a catalyst in hydrolysis of tetraethyl orthosilicate (TEOS) to form Si-containing low molecular weight species. Then the low molecular weight species diffused into the functionalized P GMA-EDMA microspheres by induction force of the amino groups to form polymer/silica hybrid microspheres. Finally, the organic polymer templates were removed by calcination, and the large-porous silica microspheres were obtained. The compositions, morphology, size distribution, specific surface area and pore size distribution of the porous silica microspheres were characterized by infrared analyzer, scanning-electron microscopy, dynamic laser scattering, the mercury intrusion method and thermal gravimetric analysis, respectively. The results show that the agglomeration of the hybrid microspheres can be overcome when the templates were functionalized with TEPA as amination reagent, and the yield of 95.7% of the monodisperse large-porous silica microspheres can be achieved with high concentration of polymer templates. The resulting large-porous silica microspheres were modified with octadecyltrichlorosilane (ODS) and the chromatographic evaluation was performed by separating the proteins and the digest of BSA. The baseline separation of seven kinds of protein standards was achieved, and the column delivered a better performance when separating BSA digests

  12. Granular flow through an aperture: Influence of the packing fraction

    Science.gov (United States)

    Aguirre, M. A.; De Schant, R.; Géminard, J.-C.

    2014-07-01

    For the last 50 years, the flow of a granular material through an aperture has been intensely studied in gravity-driven vertical systems (e.g., silos and hoppers). Nevertheless, in many industrial applications, grains are horizontally transported at constant velocity, lying on conveyor belts or floating on the surface of flowing liquids. Unlike fluid flows, that are controlled by the pressure, granular flow is not sensitive to the local pressure but rather to the local velocity of the grains at the outlet. We can also expect the flow rate to depend on the local density of the grains. Indeed, vertical systems are packed in dense configurations by gravity, but, in contrast, in horizontal systems the density can take a large range of values, potentially very small, which may significantly alter the flow rate. In the present article, we study, for different initial packing fractions, the discharge through an orifice of monodisperse grains driven at constant velocity by a horizontal conveyor belt. We report how, during the discharge, the packing fraction is modified by the presence of the outlet, and we analyze how changes in the packing fraction induce variations in the flow rate. We observe that variations of packing fraction do not affect the velocity of the grains at the outlet, and, therefore, we establish that flow-rate variations are directly related to changes in the packing fraction.

  13. Generation and stabilization of whey-based monodisperse naoemulsions using ultra-high pressure homogenization and small amphipathic co-emulsifier combinations

    Science.gov (United States)

    Ultra-high-pressure homogenization (UHPH) was used to generate monodisperse stable peanut oil nanoemulsions within a desired nanosize range (whey protein concentrate (WPC), sodium dodecyl sulfate, Triton X-100 (X100), and zwitterionic sulfobetaine-base...

  14. Effects of aerosol polydispersity on theoretical calculations of unattached fractions of radon progeny

    International Nuclear Information System (INIS)

    Bandi, F.; Khan, A.; Phillips, C.R.

    1987-01-01

    Theoretical calculations of unattached fractions of radon progeny require prediction of an attachment coefficient. Average attachment coefficients for aerosols of various count median diameters, CMD, and geometric standard deviations, σ/sub g/, are calculated using four different theories. These theories are: (1) the kinetic theory, (2) the diffusion theory, (3) the hybrid theory and (4) the kinetic-diffusion theory. Comparisons of the various calculated attachment coefficients are made and the implications of using either the kinetic or the diffusion theory to calculate unattached fractions for aerosols of various CMD and σg are discussed. Significant errors may arise in use of either the kinetic theory or the diffusion theory. Large and unacceptable errors arise in calculating unattached fractions of a polydisperse aerosol by characterizing the aerosol as monodisperse. Unattached fractions of RaA are calculated for two mine aerosols and a room aerosol

  15. Monodisperse gold-palladium alloy nanoparticles and their composition-controlled catalysis in formic acid dehydrogenation under mild conditions.

    Science.gov (United States)

    Metin, Önder; Sun, Xiaolian; Sun, Shouheng

    2013-02-07

    Monodisperse 4 nm AuPd alloy nanoparticles with controlled composition were synthesized by co-reduction of hydrogen tetrachloroaurate(III) hydrate and palladium(II) acetylacetonate with a borane-morpholine complex in oleylamine. These NPs showed high activity (TOF = 230 h(-1)) and stability in catalyzing formic acid dehydrogenation and hydrogen production in water at 50 °C without any additives.

  16. Generation of monodisperse cell-sized microdroplets using a centrifuge-based axisymmetric co-flowing microfluidic device.

    Science.gov (United States)

    Yamashita, Hitoyoshi; Morita, Masamune; Sugiura, Haruka; Fujiwara, Kei; Onoe, Hiroaki; Takinoue, Masahiro

    2015-04-01

    We report an easy-to-use generation method of biologically compatible monodisperse water-in-oil microdroplets using a glass-capillary-based microfluidic device in a tabletop mini-centrifuge. This device does not require complicated microfabrication; furthermore, only a small sample volume is required in experiments. Therefore, we believe that this method will assist biochemical and cell-biological experiments. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  17. Fractionating power and outlet stream polydispersity in asymmetrical flow field-flow fractionation. Part I: isocratic operation.

    Science.gov (United States)

    Williams, P Stephen

    2016-05-01

    Asymmetrical flow field-flow fractionation (As-FlFFF) has become the most commonly used of the field-flow fractionation techniques. However, because of the interdependence of the channel flow and the cross flow through the accumulation wall, it is the most difficult of the techniques to optimize, particularly for programmed cross flow operation. For the analysis of polydisperse samples, the optimization should ideally be guided by the predicted fractionating power. Many experimentalists, however, neglect fractionating power and rely on light scattering detection simply to confirm apparent selectivity across the breadth of the eluted peak. The size information returned by the light scattering software is assumed to dispense with any reliance on theory to predict retention, and any departure of theoretical predictions from experimental observations is therefore considered of no importance. Separation depends on efficiency as well as selectivity, however, and efficiency can be a strong function of retention. The fractionation of a polydisperse sample by field-flow fractionation never provides a perfectly separated series of monodisperse fractions at the channel outlet. The outlet stream has some residual polydispersity, and it will be shown in this manuscript that the residual polydispersity is inversely related to the fractionating power. Due to the strong dependence of light scattering intensity and its angular distribution on the size of the scattering species, the outlet polydispersity must be minimized if reliable size data are to be obtained from the light scattering detector signal. It is shown that light scattering detection should be used with careful control of fractionating power to obtain optimized analysis of polydisperse samples. Part I is concerned with isocratic operation of As-FlFFF, and part II with programmed operation.

  18. Facile Synthesis of Monodispersed Polysulfide Spheres for Building Structural Colors with High Color Visibility and Broad Viewing Angle.

    Science.gov (United States)

    Li, Feihu; Tang, Bingtao; Wu, Suli; Zhang, Shufen

    2017-01-01

    The synthesis and assembly of monodispersed colloidal spheres are currently the subject of extensive investigation to fabricate artificial structural color materials. However, artificial structural colors from general colloidal crystals still suffer from the low color visibility and strong viewing angle dependence which seriously hinder their practical application in paints, colorimetric sensors, and color displays. Herein, monodispersed polysulfide (PSF) spheres with intrinsic high refractive index (as high as 1.858) and light-absorbing characteristics are designed, synthesized through a facile polycondensation and crosslinking process between sodium disulfide and 1,2,3-trichloropropane. Owing to their high monodispersity, sufficient surface charge, and good dispersion stability, the PSF spheres can be assembled into large-scale and high-quality 3D photonic crystals. More importantly, high structural color visibility and broad viewing angle are easily achieved because the unique features of PSF can remarkably enhance the relative reflectivity and eliminate the disturbance of scattering and background light. The results of this study provide a simple and efficient strategy to create structural colors with high color visibility, which is very important for their practical application. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Nonlinear Stress Relaxation of ``Quasi-monodisperse'' Miscible Blends of cis-Polyisoprene and Poly(ptert-butylstyrene)

    Science.gov (United States)

    Watanabe, Hiroshi; Matsumiya, Yumi

    Viscoelastic relaxation was examined for entangled miscible blends of cis-polyisoprene (PI) and poly(ptert-butylstyrene) (PtBS). The terminal relaxation times of PI and PtBS therein, τPI and τPtBS, changed with the composition wPI and the molecular weights MPI and MPtBS. This ratio became unity when the wPI, MPI, and MPtBS values were chosen adequately. For example, in a blend with wPI = 0.75, MPI = 321k, and MPtBS = 91k at T = 40ûC, τPI/τPtBS = 1 and M/Me = 55 and 8.3 for PI and PtBS. Under small strains, this blend exhibited sharp, single-step terminal relaxation as similar to monodisperse homopolymers, thereby behaving as a ``quasi-monodisperse'' material. Under large step strains, the blend exhibited moderate nonlinear damping known as the type-A damping for entangled monodisperse homopolymers. Nevertheless, PI had M/Me = 55 in that blend, and homopolymers having such a large M/Me ratio exhibit very strong type-C damping. Thus, as compared to homopolymers, the nonlinearity was suppressed in the PI/PtBS blend having the large M/Me ratio. This suppression is discussed in relation to the slow Rouse retraction of the coexisting PtBS chains (having M/Me = 8.3 in the blend).

  20. Production of monodisperse respirable aerosols of 241AmO2 and evaluation of in vitro dissolution

    International Nuclear Information System (INIS)

    Boyd, H.A.; Raabe, O.G.; Peterson, P.K.

    1974-01-01

    A method is described for production of monodisperse (sigma//sub g/ less than 1.2) particles of 241 AmO 2 for use in inhalation experiments with dogs and rodents. The effects of physical and chemical factors on the production of polydisperse aerosols of 241 AmO 2 were studied and evaluated. The best aerosol was achieved when a suspension of americium hydroxide with 2.5 mg Am/ml at pH = 7.3 was aerosolized and passed through two heating columns in succession, the first at 300 0 C and the second at 1050 0 C. The particles were roughly spherical and had densities near 8 gm/cm 3 ; the aerosol AMAD and sigma/sub g/ were about 1.5 μm and 1.7, respectively. Monodisperse particles were separated and collected with the Lovelace Aerosol Particle Separator (LAPS) and subsequently suspended in deionized water with pH adjusted to 10.2 with NH 3 for nebulization to produce monodisperse aerosols for inhalation exposures. Particles collected on filters during inhalation experiments were used for evaluation of in vitro dissolution rates with two systems and various forms of a lung fluid simulant. The important role of phosphate ions in such dissolution systems was demonstrated, suggesting the potential for the equally important role of free phosphate in retarding dissolution of AmO 2 particles in the lung. (U.S.)

  1. Synthesis, characterization and magnetic properties of highly monodispersed PtNi nanoparticles

    International Nuclear Information System (INIS)

    Du, Juan-Juan; Yang, Yi; Zhang, Rong-Hua; Zhou, Xin-Wen

    2015-01-01

    In this paper, we report the controlled-synthesis of PtNi nanoparticles through galvanic displacement reaction and chemical reduction. The size, composition and morphology of the products are characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses. The structure and composition of the PtNi nanoparticles can be controlled by adjusting the synthetic conditions. The possible formation mechanism is obtained from the academic analysis and experimental studies. The results of the magnetic measurement illustrate that the PtNi nanoparticles show a superparamagnetic behavior with a blocking temperature (T B ) about 8.0 K. - Highlights: • Highly monodispersed PtNi nanoparticles were synthesized by galvanic displacement reaction. • The formation of Pt nanocrystals was the foremost step because of its self-catalysis effect. • The PtNi nanoparticles show a superparamagnetic behavior with a T B about 8.0 K

  2. Production and characterization of monodisperse uranium particles for nuclear safeguards applications

    Energy Technology Data Exchange (ETDEWEB)

    Knott, Alexander

    2016-07-01

    Environmental sampling is a very effective measure to detect undeclared nuclear activities. Generally, samples are taken as swipe samples on cotton. These swipes contain minute quantities of particulates which have an inherent signature of their production and release scenario. These inspection samples are assessed for their morphology, elemental composition and their isotopic vectors. Mass spectrometry plays a crucial role in determining the isotopic ratios of uranium. Method validation and instrument calibration with well-characterized quality control (QC)-materials, reference materials (RMs) and certified reference materials (CRMs) ensures reliable data output. Currently, the availability of suitable well defined microparticles containing uranium and plutonium reference materials is very limited. Primarily, metals, oxides and various uranium and plutonium containing solutions are commercially available. Therefore, the IAEA's Safeguards Analytical Services (SGAS) cooperates with the Institute of Nuclear Waste Management and Reactor Safety (IEK-6) at the Forschungszentrum Juelich GmbH in a joint task entitled ''Production of Particle Reference Materials''. The work presented in this thesis has been partially funded by the IAEA, Forschungszentrum Juelich GmbH and the Federal Ministry of Economic Affairs and Energy (BMWi) through the ''Joint Program on the Technical Development and Further Improvement of IAEA Safeguards between the Government of the Federal Republic of Germany and the IAEA''. The first step towards monodisperse microparticles was the development of pure uranium oxide particles made from certified reference materials. The focus of the dissertation is (1) the implementation of a working setup to produce monodisperse uranium oxide particles and (2) the characterization of these particles towards the application as QC-material. Monodisperse uranium oxide particles were produced by spray pyrolysis. It was

  3. A new method for preparing mono-dispersed nanoparticles using magnetized water

    Science.gov (United States)

    Nakhaei Pour, Ali; Gholizadeh, Mostafa; Housaindokht, Mohammadreza; Moosavi, Fatemeh; Monhemi, Hasan

    2017-04-01

    We studied the use of magnetized water on the size of the nanoparticles. Magnetized water found to reduce the diameter of the nanoparticles during a homogeneous precipitation process, which is a combination of nucleation and nuclei growth processes. We found that the modified water, which demonstrated different physical properties especially on the surface tension and viscosity, significantly influenced the both processes. Therefore, the nucleation process was initially prolonged in the homogeneous precipitation process due to the lower critical size of nucleus and higher rate of nucleation, and consequently formed smaller particles and a larger number of particles. Furthermore, the growth rate of nanoparticles was hindered owing to the higher viscosity of the water and restriction in the mass transport process. As a result, the precipitated particles with the magnetized water were eventually structured smaller particle diameter compared to the bulk. The presented method in here indicated a low cost, straightforward, and feasible technique for industrial application. In addition, this method could open a new promising perspective on nanomaterial synthesis in order to facilitate the production of monodispersed nanoparticles. Molecular dynamic confirmed that surface tension decreased as the external magnetic field was applied. Moreover, the density profile illustrated that the average number of hydrogen atoms is greater than oxygen atoms.

  4. Synthesis of Monodisperse Nanocrystals via Microreaction: Open-to-Air Synthesis with Oleylamine as a Coligand

    Directory of Open Access Journals (Sweden)

    Yang Hongwei

    2009-01-01

    Full Text Available Abstract Microreaction provides a controllable tool to synthesize CdSe nanocrystals (NCs in an accelerated fashion. However, the surface traps created during the fast growth usually result in low photoluminescence (PL efficiency for the formed products. Herein, the reproducible synthesis of highly luminescent CdSe NCs directly in open air was reported, with a microreactor as the controllable reaction tool. Spectra investigation elucidated that applying OLA both in Se and Cd stock solutions could advantageously promote the diffusion between the two precursors, resulting in narrow full-width-at-half maximum (FWHM of PL (26 nm. Meanwhile, the addition of OLA in the source solution was demonstrated helpful to improve the reactivity of Cd monomer. In this case, the focus of size distribution was accomplished during the early reaction stage. Furthermore, if the volume percentage (vol.% of OLA in the precursors exceeded a threshold of 37.5%, the resulted CdSe NCs demonstrated long-term fixing of size distribution up to 300 s. The observed phenomena facilitated the preparation of a size series of monodisperse CdSe NCs merely by the variation of residence time. With the volume percentage of OLA as 37.5% in the source solution, a 78 nm tuning of PL spectra (from 507 to 585 was obtained through the variation of residence time from 2 s to 160 s, while maintaining narrow FMWH of PL (26–31 nm and high QY of PL (35–55%.

  5. Magnetically Triggered Monodispersed Nanocomposite Fabricated by Microfluidic Approach for Drug Delivery

    KAUST Repository

    Yassine, Omar; Li, Erqiang; Alfadhel, Ahmed; Zaher, A.; Kavaldzhiev, Mincho; Thoroddsen, Sigurdur T; Kosel, Jü rgen

    2016-01-01

    Responsive microgel poly(N-isopropylacrylamide) or PNIPAM is a gel that can swell or shrink in response to external stimuli (temperature, pH, etc.). In this work, a nanocomposite gel is developed consisting of PNIPAM and magnetic iron oxide nanobeads for controlled release of liquids (like drugs) upon exposure to an alternating magnetic field. Microparticles of the nanocomposite are fabricated efficiently with a monodisperse size distribution and a diameter ranging from 20 to 500  µ m at a rate of up to 1 kHz using a simple and inexpensive microfluidic system. The nanocomposite is heated through magnetic losses, which is exploited for a remotely stimulated liquid release. The efficiency of the microparticles for controlled drug release applications is tested with a solution of Rhodamine B as a liquid drug model. In continuous and pulsatile mode, a release of 7% and 80% was achieved, respectively. Compared to external thermal actuation that heats the entire surrounding or embedded heaters that need complex fabrication steps, the magnetic actuation provides localized heating and is easy to implement with our microfluidic fabrication method.

  6. Growth of monodisperse nanocrystals of cerium oxide during synthesis and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie; Divya, Damodaran [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India); Remani, Kottayilpadi C. [Sree Neelakanda Government Sanskrit College, Department of Chemistry (India); Sreeremya, Thadathil S. [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR) (India)

    2010-06-15

    Monodisperse cerium oxide nanocrystals have been successfully synthesised using simple ammonia precipitation technique from cerium(III) nitrate solution at different temperatures in the range 35-80 {sup o}C. The activation energy for growth of CeO{sub 2} nanocrystals during the precipitation is calculated as 11.54 kJ/mol using Arrhenius plot. Average crystal diameter was obtained from XRD analysis, HR-TEM and light scattering (PCS). The analysis of size data from HR-TEM images and PCS clearly indicated the formation of highly crystalline CeO{sub 2} particles in narrow size range. CeO{sub 2} nanocrystals precipitated at 35 {sup o}C were further annealed at temperatures in the range 300-700 {sup o}C. The activation energy for crystal growth during annealing is also calculated and is close to the reported values. An effort is made to predict the mechanism of crystal growth during the precipitation and annealing.

  7. Morphology controlled synthesis of monodisperse cobalt hydroxide for supercapacitor with high performance and long cycle life

    Science.gov (United States)

    Tang, Yongfu; Liu, Yanyan; Yu, Shengxue; Mu, Shichun; Xiao, Shaohua; Zhao, Yufeng; Gao, Faming

    2014-06-01

    A facile hydrothermal process with hexadecyltrimethyl ammonium bromide (CTAB) as the soft template is proposed to tune the morphology and size of cobalt hydroxide (Co(OH)2). Monodisperse β-phase Co(OH)2 nanowires with uniform size are obtained by controlling the CTAB content and the reaction time. Due to the uniform well-defined morphology and stable structure, the Co(OH)2 nanowires material exhibits high capacitive performance and long cycle life. The specific capacitance of the Co(OH)2 nanowires electrode is 358 F g-1 at 0.5 A g-1, and even 325 F g-1 at 10 A g-1. The specific capacitance retention is 86.3% after 5000 charge-discharge cycles at 2 A g-1. Moreover, the asymmetric supercapacitor is assembled with Co(OH)2 nanowires and nitrite acid treated activated carbon (NTAC), which shows an energy density of 13.6 Wh kg-1 at the power density of 153 W kg-1 under a high voltage of 1.6 V, and 13.1 Wh kg-1 even at the power density of 1.88 kW kg-1.

  8. Investigation of Monodisperse Dendrimeric Polysaccharide Nanoparticle Dispersions Using Small Angle Neutron Scattering

    Science.gov (United States)

    Atkinson, John; Nickels, Jonathan; Papp-Szabo, Erzsi; Katsaras, John; Dutcher, John

    2015-03-01

    Phytoglycogen is a highly branched polysaccharide that is very similar to the energy storage molecule glycogen. We have isolated monodisperse phytoglycogen nanoparticles from corn and these particles are attractive for applications in the cosmetic, food and beverage, and biomedical industries. Many of these promising applications are due to the special interaction between the nanoparticles and water, which results in: (1) high solubility; (2) low viscosity and high stability in aqueous dispersions; and (3) a remarkable capacity to sequester and retain water. Our rheology measurements indicate that the nanoparticles behave like hard spheres in water, with the viscosity diverging for concentrations >25% (w/w). Because of this, aqueous suspensions of phytoglycogen provide an ideal platform for detailed testing of theories of colloidal glasses and jamming. To further explore the interaction of the phytoglycogen particles and water, we have performed small angle neutron scattering (SANS) measurements on the Extended Q-Range SANS (EQ-SANS) diffractometer at the Spallation Neutron Source at Oak Ridge National Laboratory. Measurements performed on phytoglycogen dispersions in mixtures of hydrogenated and deuterated water have allowed us to determine the particle size and average particle spacing as a function of the phytoglycogen concentration in the limits of dilute and concentrated dispersions.

  9. Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

    Science.gov (United States)

    Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

    2013-10-01

    In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles.

  10. Monodispersed MnO nanoparticles with epitaxial Mn{sub 3}O{sub 4} shells

    Energy Technology Data Exchange (ETDEWEB)

    Berkowitz, A E; Rodriguez, G F [Department of Physics, University of California, San Diego La Jolla, CA 92093 (United States); Hong, J I; Fullerton, E E [Center for Magnetic Recording Research, University of California-San Diego La Jolla, CA 92093 (United States); An, K; Hyeon, T [National Creative Research Initiative Center for Oxide Nanocrystalline Materials, Seoul National University, Seoul 151-744 (Korea, Republic of); Agarwal, N; Smith, D J [School of Materials and Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2008-07-07

    We report the microstructural and magnetic properties of monodispersed nanoparticles (NPs) of antiferromagnetic MnO (T{sub N} = 118 K), with epitaxial ferrimagnetic Mn{sub 3}O{sub 4} (T{sub C} = 43 K) shells. Above T{sub C}, an unusually large magnetization is present, produced by the uncompensated spins (UCSs) on the surface of the MnO particles. These spins impart a net anisotropy to the MnO particles that is approximately three orders of magnitude larger than the bulk value. As a result, an anomalously high blocking temperature is exhibited by the MnO particles, and finite coercivity and exchange bias are present above T{sub C}. When field cooled below T{sub C}, a strong exchange bias was established in the Mn{sub 3}O{sub 4} shells as a result of high net anisotropy of the MnO particles. A large coercivity was also observed. Models of several aspects of the behaviour of this unusual system emphasized the essential role of the UCSs on the surfaces of the MnO NPs.

  11. Magnetically Triggered Monodispersed Nanocomposite Fabricated by Microfluidic Approach for Drug Delivery

    Directory of Open Access Journals (Sweden)

    O. Yassine

    2016-01-01

    Full Text Available Responsive microgel poly(N-isopropylacrylamide or PNIPAM is a gel that can swell or shrink in response to external stimuli (temperature, pH, etc.. In this work, a nanocomposite gel is developed consisting of PNIPAM and magnetic iron oxide nanobeads for controlled release of liquids (like drugs upon exposure to an alternating magnetic field. Microparticles of the nanocomposite are fabricated efficiently with a monodisperse size distribution and a diameter ranging from 20 to 500 µm at a rate of up to 1 kHz using a simple and inexpensive microfluidic system. The nanocomposite is heated through magnetic losses, which is exploited for a remotely stimulated liquid release. The efficiency of the microparticles for controlled drug release applications is tested with a solution of Rhodamine B as a liquid drug model. In continuous and pulsatile mode, a release of 7% and 80% was achieved, respectively. Compared to external thermal actuation that heats the entire surrounding or embedded heaters that need complex fabrication steps, the magnetic actuation provides localized heating and is easy to implement with our microfluidic fabrication method.

  12. Retention studies in rats exposed to monodisperse aerosols of /sup 198/Au labeled carnauba wax particles

    Energy Technology Data Exchange (ETDEWEB)

    Tarroni, G.; Bassi, P.; Belvisi, M.B.; Bianco, A.

    1981-01-01

    Rats were exposed to monodisperse carnauba wax aerosols labeled with colloidal /sup 198/Au and the retained activity was followed both in vivo and in the lungs of serially sacrified animals. In vitro and in vivo tests have shown low leaching rates of the label. The deposited activity could then be followed without correction for particle solubility. The activity in vivo shows a three-exponential decay, characterized by half-times of a few hours, one day, and one month corresponding to the clearance of the material deposited respectively in the extrathoracic airways, in the tracheo-bronchial, and in the alveolar regions. A correlation was found between long term cleared activity and particle size but no correlation was found between particle size and clearance half times in the size range investigated. Statistical evaluation of the activity vs time in vivo and in excised lungs has shown that the long term retained activity pertains to the alveolar region and, if a large number of animals is not used, more accurate data of pulmonary clearance can be obtained by in vivo measurements than by serial sacrifices.

  13. Self-assembly of monodisperse starburst carbon spheres into hierarchically organized nanostructured supercapacitor electrodes.

    Science.gov (United States)

    Kim, Sung-Kon; Jung, Euiyeon; Goodman, Matthew D; Schweizer, Kenneth S; Tatsuda, Narihito; Yano, Kazuhisa; Braun, Paul V

    2015-05-06

    We report a three-dimensional (3D) porous carbon electrode containing both nanoscale and microscale porosity, which has been hierarchically organized to provide efficient ion and electron transport. The electrode organization is provided via the colloidal self-assembly of monodisperse starburst carbon spheres (MSCSs). The periodic close-packing of the MSCSs provides continuous pores inside the 3D structure that facilitate ion and electron transport (electrode electrical conductivity ∼0.35 S m(-1)), and the internal meso- and micropores of the MSCS provide a good specific capacitance. The capacitance of the 3D-ordered porous MSCS electrode is ∼58 F g(-1) at 0.58 A g(-1), 48% larger than that of disordered MSCS electrode at the same rate. At 1 A g(-1) the capacitance of the ordered electrode is 57 F g(-1) (95% of the 0.24 A g(-1) value), which is 64% greater than the capacitance of the disordered electrode at the same rate. The ordered electrode preserves 95% of its initial capacitance after 4000 charging/discharging cycles.

  14. Observation of Quantum Confinement in Monodisperse Methylammonium Lead Halide Perovskite Nanocrystals Embedded in Mesoporous Silica.

    Science.gov (United States)

    Malgras, Victor; Tominaka, Satoshi; Ryan, James W; Henzie, Joel; Takei, Toshiaki; Ohara, Koji; Yamauchi, Yusuke

    2016-10-13

    Hybrid organic-inorganic metal halide perovskites have fascinating electronic properties and have already been implemented in various devices. Although the behavior of bulk metal halide perovskites has been widely studied, the properties of perovskite nanocrystals are less well-understood because synthesizing them is still very challenging, in part because of stability. Here we demonstrate a simple and versatile method to grow monodisperse CH 3 NH 3 PbBr x I x-3 perovskite nanocrystals inside mesoporous silica templates. The size of the nanocrystal is governed by the pore size of the templates (3.3, 3.7, 4.2, 6.2, and 7.1 nm). In-depth structural analysis shows that the nanocrystals maintain the perovskite crystal structure, but it is slightly distorted. Quantum confinement was observed by tuning the size of the particles via the template. This approach provides an additional route to tune the optical bandgap of the nanocrystal. The level of quantum confinement was modeled taking into account the dimensions of the rod-shaped nanocrystals and their close packing inside the channels of the template. Photoluminescence measurements on CH 3 NH 3 PbBr clearly show a shift from green to blue as the pore size is decreased. Synthesizing perovskite nanostructures in templates improves their stability and enables tunable electronic properties via quantum confinement. These structures may be useful as reference materials for comparison with other perovskites, or as functional materials in all solid-state light-emitting diodes.

  15. Dosimetry of 239Pu in dogs that inhaled monodisperse aerosols of 239PuO2

    International Nuclear Information System (INIS)

    Guilmette, R.A.; Muggenburg, B.A.; Hahn, F.F.; Mewhinney, J.A.; Seiler, F.A.; Boecker, B.B.; McClellan, R.O.

    1987-01-01

    Existing data from human exposure cases and experimental animal studies on the fate and dosimetry of inhaled insoluble Pu particles are inadequate to provide a comprehensive description and evaluation of the tissues at risk from the alpha radiations of Pu. To improve our knowledge of the dosimetry of inhaled insoluble 239 PuO 2 , this paper describes the uptake and retention of 239 Pu in the tissues of dogs that received single inhalation exposures to monodisperse aerosols of 239 PuO 2 . These data include times through 3 years after exposure. Using analytical functions fitted to each tissue data set, 1100-day radiation doses were calculated for lung, liver, skeleton, kidney, spleen, and tracheobronchial, mediastinal, sternal, hepatic, mandibular, and retropharyngeal lymph nodes. The dosimetry results suggest that the lung and lymph nodes associated with lymphatic drainage of the respiratory tract are the principal sites of alpha irradiation. However, the doses for the different respiratory tract lymph nodes vary by a factor of 2000, suggesting that assuming equivalent doses to respiratory tract lymph nodes is not appropriate. Other tissues receive radiation doses also but at levels one to three orders of magnitude less than the lung. Particle size dependence on uptake and retention was noted for the skeleton, mediastinal lymph nodes, hepatic lymph nodes, retropharyngeal lymph nodes, and mandibular lymph nodes

  16. Preparation of monodisperse microbubbles using an integrated embedded capillary T-junction with electrohydrodynamic focusing.

    Science.gov (United States)

    Parhizkar, Maryam; Stride, Eleanor; Edirisinghe, Mohan

    2014-07-21

    This work investigates the generation of monodisperse microbubbles using a microfluidic setup combined with electrohydrodynamic processing. A basic T-junction microfluidic device was modified by applying an electrical potential difference across the outlet channel. A model glycerol air system was selected for the experiments. In order to investigate the influence of the electric field strength on bubble formation, the applied voltage was increased systematically up to 21 kV. The effect of solution viscosity and electrical conductivity was also investigated. It was found that with increasing electrical potential difference, the size of the microbubbles reduced to ~25% of the capillary diameter whilst their size distribution remained narrow (polydispersity index ~1%). A critical value of 12 kV was found above which no further significant reduction in the size of the microbubbles was observed. The findings suggest that the size of the bubbles formed in the T-junction (i.e. in the absence of the electric field) is strongly influenced by the viscosity of the solution. The eventual size of bubbles produced by the composite device, however, was only weakly dependent upon viscosity. Further experiments, in which the solution electrical conductivity was varied by the addition of a salt indicated that this had a much stronger influence upon bubble size.

  17. Magnetically Triggered Monodispersed Nanocomposite Fabricated by Microfluidic Approach for Drug Delivery

    KAUST Repository

    Yassine, Omar

    2016-01-01

    Responsive microgel poly(N-isopropylacrylamide) or PNIPAM is a gel that can swell or shrink in response to external stimuli (temperature, pH, etc.). In this work, a nanocomposite gel is developed consisting of PNIPAM and magnetic iron oxide nanobeads for controlled release of liquids (like drugs) upon exposure to an alternating magnetic field. Microparticles of the nanocomposite are fabricated efficiently with a monodisperse size distribution and a diameter ranging from 20 to 500  µ m at a rate of up to 1 kHz using a simple and inexpensive microfluidic system. The nanocomposite is heated through magnetic losses, which is exploited for a remotely stimulated liquid release. The efficiency of the microparticles for controlled drug release applications is tested with a solution of Rhodamine B as a liquid drug model. In continuous and pulsatile mode, a release of 7% and 80% was achieved, respectively. Compared to external thermal actuation that heats the entire surrounding or embedded heaters that need complex fabrication steps, the magnetic actuation provides localized heating and is easy to implement with our microfluidic fabrication method.

  18. Undecylprodigiosin conjugated monodisperse gold nanoparticles efficiently cause apoptosis in colon cancer cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Nikodinovic-Runic, Jasmina; Mojic, Marija; Kang, Yijin; Maksimovic-Ivanic, Danijela; Mijatovic, Sanja; Vasiljevic, Branka; Stamenkovic, Vojislav R.; Senerovic, Lidija

    2014-01-01

    Bacterial pigment undecylprodigiosin (UP) was produced using Streptomyces sp. JS520 and conjugated to monodisperse gold nanoparticles (UP-Au). Both UP and UP-Au showed cytocidal activity towards melanoma (A375), lung carcinoma (A549), breast cancer (MCF-7) and colon cancer (HCT-116) cells, inducing apoptosis with IC50 values ranging from 0.4 to 4 mu g ml(-1). Unconjugated UP had a tendency to lose its activity over time and to change biophysical characteristics over pH. The loss of the pigment potency was overcome by conjugation with gold nanoparticles. UP-Au exhibited high stability over pH 3.8 to 7.4 and its activity remained unaffected in time. Nano-packing changed the mechanism of UP toxicity by converting the intracellular signals from a mitochondrial dependent to a mitochondrial independent apoptotic process. The availability of nonpyrogenic UP in high amounts, together with specific anticancer activity and improved stability in the complex with gold nanoparticles, presents a novel platform for further development of UP-Au complexes as an anticancer drug suitable for clinical applications.

  19. Monodispersed porous flowerlike PtAu nanocrystals as effective electrocatalysts for ethanol oxidation

    Science.gov (United States)

    Li, Shumin; Xu, Hui; Xiong, Zhiping; Zhang, Ke; Wang, Caiqin; Yan, Bo; Guo, Jun; Du, Yukou

    2017-11-01

    Designing and tuning the bimetallic nanoparticles with desirable morphology and structure can embody them with greatly enhanced electrocatalytic activity and stability towards liquid fuel oxidation. We herein reported a facile one-pot method for the controlled synthesis of monodispersed binary PtAu nanoflowers with abundant exposed surface area. Owing to its fantastic structure, synergistic and electronic effect, such as-prepared PtAu nanoflowers exhibited outstandingly high electrocatalytic activity with the mass activity of 6482 mA mg-1 towards ethanol oxidation, which is 28.3 times higher than that of commercial Pt/C (227 mA mg-1). More interesting, the present PtAu nanoflower catalysts are more stable for the ethanol oxidation reaction in the alkaline with lower current density decay and retained a much higher current density after successive CVs of 500 cycles than that of commercial Pt/C. This work may open a new way for maximizing the catalytic performance of electrocatalysts towards ethanol oxidation by synthesizing shape-controlled alloy nanoparticles with more surface active sites to enhance the performances of direct fuel cells reaction, chemical conversion, and beyond.

  20. Synthesis and characterization of titania-based monodisperse fluorescent europium nanoparticles for biolabeling

    International Nuclear Information System (INIS)

    Tan Mingqian; Wang Guilan; Ye Zhiqiang; Yuan Jingli

    2006-01-01

    Inorganic-organic hybrid titania-based nanoparticles covalently bound to a fluorescent Eu 3+ chelate of 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl) chlorosulfo-o-terphenyl (BHHCT-Eu 3+ ) were synthesized by a sol-gel technique. A conjugate of BHHCT with 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (APTS) was used as a precursor for the nanoparticle preparation and monodisperse nanoparticles consisting of titania network and silica sub-network covalently bound to the Eu 3+ chelate were prepared by the copolymerization of APTS-BHHCT conjugate, titanium tetraisopropoxide (TTIP) and free APTS in EuCl 3 water-alcohol solution. The effects of reaction conditions on size and fluorescence lifetime of the nanoparticles were investigated. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are near spherical and strongly fluorescent having a fluorescence quantum yield of 11.6% and a long fluorescence lifetime of ∼0.4 ms. The direct-introduced amino groups on the nanoparticle's surface by using free APTS in nanoparticle preparation facilitated the biolabeling process of the nanoparticles. The nanoparticle-labeled streptavidin (SA) was prepared and used in a sandwich-type time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid phase carrier. The method gives a detection limit of 66 pg/ml for the PSA assay

  1. A novel method for the synthesis of monodisperse gold-coated silica nanoparticles

    International Nuclear Information System (INIS)

    English, Michael D.; Waclawik, Eric R.

    2012-01-01

    Monodisperse silica nanoparticles were synthesised by the well-known Stober protocol, then dispersed in acetonitrile (ACN) and subsequently added to a bisacetonitrile gold(I) coordination complex ([Au(MeCN) 2 ] + ) in ACN. The silica hydroxyl groups were deprotonated in the presence of ACN, generating a formal negative charge on the siloxy groups. This allowed the [Au(MeCN) 2 ] + complex to undergo ligand exchange with the silica nanoparticles and form a surface coordination complex with reduction to metallic gold (Au 0 ) proceeding by an inner sphere mechanism. The residual [Au(MeCN) 2 ] + complex was allowed to react with water, disproportionating into Au 0 and Au(III), respectively, with the Au 0 adding to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be suitable for the conventional reduction of Au(III) to Au 0 by ascorbic acid (ASC). This process generated a thin and uniform gold coating on the silica nanoparticles. The silica NPs batches synthesised were in a size range from 45 to 460 nm. Of these silica NP batches, the size range from 400 to 480 nm were used for the gold-coating experiments.

  2. Synthetic Polymers at Interfaces: Monodisperse Emulsions Multiple Emulsions and Liquid Marbles

    Science.gov (United States)

    Sun, Guanqing

    The adsorption of polymeric materials at interfaces is an energetically favorable process which is investigated in much diversified fields, such as emulsions, bubbles, foams, liquid marbles. Pickering emulsion, which is emulsion stabilized by solid particles has been investigated for over one century and preparation of Pickering emulsion with narrow size distribution is crucial for both the theoretical study of the stabilization mechanism and practical application, such as templated fabrication of colloidosomes. The precise control over the size and functionality of polymer latices allows the preparation of monodisperse Pickering emulsions with desired sizes through SPG membrane emulsification at rather rapid rate compared to microfludic production. Double or multiple emulsions have long been investigated but its rapid destabilization has always been a major obstacle in applying them into practical applications. The modern living polymerization techniques allow us to prepare polymers with designed structure of block copolymers which makes it possible to prepare ultra-stable multiple emulsions. The precise tuning of the ratio of hydrophobic part over the hydrophilic can unveil the stabilization mechanism. Liquid marble is a new type of materials of which liquid droplets are coated by dry particles. The coating of an outer layer of dry particles renders the liquid droplets non-sticky at solid surface which is useful in transportation of small amount of liquid without leakage at extreme low friction force. The property of liquid marbles relies largely on the stabilizers and the drying condition of polymeric latices is shown to have great influence on the property of liquid marbles. Firstly, an introduction to the interfacial and colloidal science with special attention to topics on emulsions, multiple emulsion and liquid marbles is given in Chapter 1. The unique features of an interface and a discussion on the definition of colloids are introduced prior to the

  3. Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.

    Science.gov (United States)

    Matsumoto, Hideki; Nagao, Daisuke; Konno, Mikio

    2010-03-16

    Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

  4. Fractional quantum mechanics

    CERN Document Server

    Laskin, Nick

    2018-01-01

    Fractional quantum mechanics is a recently emerged and rapidly developing field of quantum physics. This is the first monograph on fundamentals and physical applications of fractional quantum mechanics, written by its founder. The fractional Schrödinger equation and the fractional path integral are new fundamental physical concepts introduced and elaborated in the book. The fractional Schrödinger equation is a manifestation of fractional quantum mechanics. The fractional path integral is a new mathematical tool based on integration over Lévy flights. The fractional path integral method enhances the well-known Feynman path integral framework. Related topics covered in the text include time fractional quantum mechanics, fractional statistical mechanics, fractional classical mechanics and the α-stable Lévy random process. The book is well-suited for theorists, pure and applied mathematicians, solid-state physicists, chemists, and others working with the Schrödinger equation, the path integral technique...

  5. Fractional vector calculus and fractional Maxwell's equations

    International Nuclear Information System (INIS)

    Tarasov, Vasily E.

    2008-01-01

    The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered

  6. Fractional statistics and fractional quantized Hall effect

    International Nuclear Information System (INIS)

    Tao, R.; Wu, Y.S.

    1985-01-01

    The authors suggest that the origin of the odd-denominator rule observed in the fractional quantized Hall effect (FQHE) may lie in fractional statistics which govern quasiparticles in FQHE. A theorem concerning statistics of clusters of quasiparticles implies that fractional statistics do not allow coexistence of a large number of quasiparticles at fillings with an even denominator. Thus, no Hall plateau can be formed at these fillings, regardless of the presence of an energy gap. 15 references

  7. Initialized Fractional Calculus

    Science.gov (United States)

    Lorenzo, Carl F.; Hartley, Tom T.

    2000-01-01

    This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.

  8. Tempered fractional calculus

    Energy Technology Data Exchange (ETDEWEB)

    Sabzikar, Farzad, E-mail: sabzika2@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Meerschaert, Mark M., E-mail: mcubed@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Chen, Jinghua, E-mail: cjhdzdz@163.com [School of Sciences, Jimei University, Xiamen, Fujian, 361021 (China)

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  9. Tempered fractional calculus

    Science.gov (United States)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  10. Tempered fractional calculus

    International Nuclear Information System (INIS)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-01-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series

  11. Higher fractions theory of fractional hall effect

    International Nuclear Information System (INIS)

    Kostadinov, I.Z.; Popov, V.N.

    1985-07-01

    A theory of fractional quantum Hall effect is generalized to higher fractions. N-particle model interaction is used and the gap is expressed through n-particles wave function. The excitation spectrum in general and the mean field critical behaviour are determined. The Hall conductivity is calculated from first principles. (author)

  12. Synthesis, characterization and magnetic properties of monodisperse Ni, Zn-ferrite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Sanjeev, E-mail: sanjeevkumar.dubey2@gmail.com [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Kumar, Pankaj [University of Petroleum and Energy Studies, Dehradun, Uttarakhand (India); Singh, Vaishali [University School of Basic and Applied Science (India); Kumar Mandal, Uttam [University of Chemical Technology, GGS Indraprastha University, Sector 16, Dwarka, Delhi 110403 (India); Kumar Kotnala, Ravinder [National Physical laboratory, New Delhi 110012 (India)

    2015-04-01

    Synthesization of monodisperse Ni, Zn-ferrite (Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4}, x=1, 0.8, 0.6, 0.5, 0.4, 0.2, 0.0) nanocrystals has been achieved by the inverse microemulsion method using CTAB as surfactant and kerosene as an oil phase. The detailed characterization of the synthesized nanocrystals and measurement of the magnetic properties has been done by techniques like X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infrared spectroscopy (FITR) and Vibrating Sample Magnetometer (VSM) respectively. The relationship between the structure and composition of the nanocrystals with magnetic properties has been investigated. The nanocrystals size is found to be in the range 1–5 nm. The effect of Zn substitution on size and magnetic properties has been studied. It has been observed that magnetism changed from ferromagnetic at X= 0 to super paramagnetic to paramagnetic at X=1 as Zn concentration increased. The Curie temperature is found to decrease with an increase in Zn concentration. - Highlights: • Reverse microemulsion route is very facile route for synthesis of Ni{sub 1−x}Zn{sub x}Fe{sub 2}O{sub 4} ferrite. • Presence of Zn changes the structural and magnetic properties of the Zn substituted NiFe{sub 2}O{sub 4.} • The lattice constant increases with the increase in Zn substitution. • The curie temperature decreases with Zn concentration appreciably. • Magnetic behavior varies from ferromagnetic at x=0 to superparamagnetic to paramagnetic at x=1.

  13. Atomically Monodisperse Nickel Nanoclusters as Highly Active Electrocatalysts for Water Oxidation

    KAUST Repository

    Joya, Khurram

    2016-04-08

    Achieving water splitting at low overpotential with high oxygen evolution efficiency and stability is important for realizing solar to chemical energy conversion devices. Herein we report the synthesis, characterization and electrochemical evaluation of highly active nickel nanoclusters (Ni NCs) for water oxidation at low overpotential. These atomically precise and monodisperse Ni NCs are characterized by using UV-visible absorption spectroscopy, single crystal X-ray diffraction and mass spectrometry. The molecular formulae of these Ni NCs are found to be Ni4(PET)8 and Ni6(PET)12 and are highly active electrocatalysts for oxygen evolution without any pre-conditioning. Ni4(PET)8 are slightly better catalysts than Ni6(PET)12 and initiate the oxygen evolution at an amazingly low overpotential of ~1.51 V (vs RHE; η ≈ 280 mV). The peak oxygen evolution current density (J) of ~150 mA cm–2 at 2.0 V (vs. RHE) with a Tafel slope of 38 mV dec–1 is observed using Ni4(PET)8. These results are comparable to the state-of-the art RuO2 electrocatalyst, which is highly expensive and rare compared to Ni-based materials. Sustained oxygen generation for several hours with an applied current density of 20 mA cm–2 demonstrates the long-term stability and activity of these Ni NCs towards electrocatalytic water oxidation. This unique approach provides a facile method to prepare cost-effective, nanoscale and highly efficient electrocatalysts for water oxidation.

  14. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yan-yu [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Yang, Hui, E-mail: 549456369@qq.com [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Tao [School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi' an 710021 (China); Wang, Chuang [Department of Highway & Bridge, Shaanxi Railway Institute, Weinan 714000 (China)

    2016-11-25

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag{sup +} (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO{sub 3}) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO{sub 3} concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH{sub 2}, −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

  15. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    International Nuclear Information System (INIS)

    Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

    2016-01-01

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag + (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO 3 ) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO 3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV–vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10–16 nm. FTIR analysis revealed that biological macromolecules with groups of −NH 2 , −OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications. - Highlights: • Monodisperse silver nanoparticles were first prepared by a green synthetical way through Ginkgo Biloba leaf extract. • The synthesized AgNPs is of high crystallinity, stable and good dispersion with smaller sizes between 10–16 nm. • The achieved AgNPs exhibits good antibacterial activities. • The biosynthesis method is advantageous for its cost effectiveness, availability, portability, nontoxic and environmentally benign.

  16. Touch communicates distinct emotions.

    Science.gov (United States)

    Hertenstein, Matthew J; Keltner, Dacher; App, Betsy; Bulleit, Brittany A; Jaskolka, Ariane R

    2006-08-01

    The study of emotional signaling has focused almost exclusively on the face and voice. In 2 studies, the authors investigated whether people can identify emotions from the experience of being touched by a stranger on the arm (without seeing the touch). In the 3rd study, they investigated whether observers can identify emotions from watching someone being touched on the arm. Two kinds of evidence suggest that humans can communicate numerous emotions with touch. First, participants in the United States (Study 1) and Spain (Study 2) could decode anger, fear, disgust, love, gratitude, and sympathy via touch at much-better-than-chance levels. Second, fine-grained coding documented specific touch behaviors associated with different emotions. In Study 3, the authors provide evidence that participants can accurately decode distinct emotions by merely watching others communicate via touch. The findings are discussed in terms of their contributions to affective science and the evolution of altruism and cooperation. (c) 2006 APA, all rights reserved

  17. Asphalt chemical fractionation

    International Nuclear Information System (INIS)

    Obando P, Klever N.

    1998-01-01

    Asphalt fractionation were carried out in the Esmeraldas Oil Refinery using n-pentane, SiO 2 and different mixture of benzene- methane. The fractions obtained were analyzed by Fourier's Transformed Infrared Spectrophotometry (FTIR)

  18. Macrocyclic receptors immobilized to monodisperse porous polymer particles by chemical grafting and physical impregnation for strontium capture: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yang [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing (China); Du, Yi [Department of Chemical Engineering, Laboratory for Advanced Materials, Tsinghua University, Beijing (China); Lv, Dachao [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing (China); Ye, Gang, E-mail: yegang@tsinghua.edu.cn [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing (China); Wang, Jianchen [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing (China)

    2014-06-01

    Graphical abstract: Macrocyclic receptors grafted to monodisperse porous polymer particles for Sr(II) capture. - Highlights: • Synthesis of novel selective Sr adsorbent grafted with macrocyclic receptors. • New monodisperse porous polymer particles used to promote Sr adsorption. • Comparative study and discussion on adsorption behaviour and mechanism. • A chromatographic process proposed for Sr separation in simulated HLLW. - Abstract: Separation of strontium is of great significance for radioactive waste treatment and environmental remediation after nuclear accidents. In this work, a novel class of adsorbent (Crown-g-MPPPs) was synthesized by chemical grafting a macrocyclic ether receptor to monodisperse porous polymer particles (MPPPs) for strontium adsorption. Meanwhile, a counterpart material (Crown@MPPPs) with the receptor molecules immobilized to the MPPPs substrate by physical impregnation was prepared. To investigate how the immobilization manner and distribution of the receptors influence the adsorption ability, a comparative study on the adsorption behaviour of the two materials towards Sr(II) in HNO{sub 3} media was accomplished. Due to the shorter diffusion path and covalently-bonded structure, Crown-g-MPPPs showed faster adsorption kinetics and better stability for cycle use. While Crown@MPPPs had the advantages of facile synthesis and higher adsorption capacity, owing to the absence of conformational constraint to form complexation with Sr(II). Kinetic functions (Lagergren pseudo-first-order/pseudo-second-order functions) and adsorption isotherm models (Langmuir/Freundlich models) were used to fit the experimental data and examine the adsorption mechanism. On this basis, a chromatographic process was proposed by using Crown@MPPPs for an effective separation of Sr(II) (91%) in simulated high level liquid waste (HLLW)

  19. High performance of visible-NIR broad spectral photocurrent application of monodisperse PbSe nanocubes decorated on rGO sheets

    Science.gov (United States)

    Ghorban Shiravizadeh, A.; Elahi, S. M.; Sebt, S. A.; Yousefi, Ramin

    2018-02-01

    In this work, the photoresponse performance of monodisperse PbSe nanocubes in the range of visible and near-infrared (NIR) (400-1500 nm) regions was enhanced by reduced graphene oxide (rGO). A simple cost-effective method is presented to synthesize monodisperse PbSe nanocubes (NCs) that are decorated on the rGO sheets. By the addition of PbSe/rGO nanocomposites with different rGO concentrations, pristine PbSe NCs were synthesized with the same method. Microscopy images showed that the size of NCs was smaller than the exciton Bohr radius (46 nm) of PbSe bulk. Therefore, the UV-Vis-IR spectroscopy result revealed that the PbSe/rGO samples had absorption peaks in the NIR region around 1650 nm and showed a blue shift compared to the absorption peak of the PbSe bulk. J-V measurements of the samples indicated that monodisperse PbSe/rGO nanocomposites had a higher resistance than the other samples under dark condition. On the other hand, the resistance of the monodisperse PbSe/rGO nanocomposites decreased under different light source illuminations while the resistance of the other samples was increased under illumination. Photodetector measurements indicated that the monodisperse morphology of the PbSe NCs enhanced the photoresponse speed and photocurrent intensity. In addition, responsivity (R) and detectivity (D*) of the samples were higher in the NIR region.

  20. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation.

    Science.gov (United States)

    Günal, Gülçin; Kip, Çiğdem; Eda Öğüt, S; İlhan, Hasan; Kibar, Güneş; Tuncel, Ali

    2018-02-01

    Monodisperse silica microspheres with bimodal pore-size distribution were proposed as a high performance sorbent for DNA isolation in batch fashion under equilibrium conditions. The proposed sorbent including both macroporous and mesoporous compartments was synthesized 5.1 μm in-size, by a "staged shape templated hydrolysis and condensation method". Hydrophilic polymer based sorbents were also obtained in the form of monodisperse-macroporous microspheres ca 5.5 μm in size, with different functionalities, by a developed "multi-stage microsuspension copolymerization" technique. The batch DNA isolation performance of proposed material was comparatively investigated using polymer based sorbents with similar morphologies. Among all sorbents tried, the best DNA isolation performance was achieved with the monodisperse silica microspheres with bimodal pore size distribution. The collocation of interconnected mesoporous and macroporous compartments within the monodisperse silica microspheres provided a high surface area and reduced the intraparticular mass transfer resistance and made easier both the adsorption and desorption of DNA. Among the polymer based sorbents, higher DNA isolation yields were achieved with the monodisperse-macroporous polymer microspheres carrying trimethoxysilyl and quaternary ammonium functionalities. However, batch DNA isolation performances of polymer based sorbents were significantly lower with respect to the silica microspheres.

  1. Existence Results for a Family of Equations of Fractional Resolvent

    International Nuclear Information System (INIS)

    Ibrahim, R.W.; Qasem, S.A.; Zailan Siri

    2015-01-01

    This study deals with the presence and distinction of bounded m-solutions (type mild) for a family of generalized integral and differential equations of spot order with fractional resolvent and indefinite delay. (author)

  2. Synthesis of Monodispersed Gold Nanoparticles with Exceptional Colloidal Stability with Grafted Polyethylene Glycol-g-polyvinyl Alcohol

    Directory of Open Access Journals (Sweden)

    Alaaldin M. Alkilany

    2015-01-01

    Full Text Available Herein, we report the synthesis of spherical gold nanoparticles with tunable core size (23–79 nm in the presence of polyethylene glycol-g-polyvinyl alcohol (PEG-g-PVA grafted copolymer as a reducing, capping, and stabilizing agent in a one-step protocol. The resulted PEG-g-PVA-capped gold nanoparticles are monodispersed with an exceptional colloidal stability against salt addition, repeated centrifugation, and extensive dialysis. The effect of various synthesis parameters and the kinetic/mechanism of the nanoparticle formation are discussed.

  3. Impact electrochemistry on screen-printed electrodes for the detection of monodispersed silver nanoparticles of sizes 10-107 nm.

    Science.gov (United States)

    Nasir, Muhammad Zafir Mohamad; Pumera, Martin

    2016-10-12

    Impact electrochemistry provides a useful alternative technique for the detection of silver nanoparticles in solutions. The combined use of impact electrochemistry on screen-printed electrodes (SPEs) for the successful detection of silver nanoparticles provides an avenue for future on-site, point-of-care detection devices to be made for environmental, medicinal and biological uses. Here we discuss the use of screen-printed electrodes for the detection of well-defined monodispersed silver nanoparticles of sizes 10, 20, 40, 80, and 107 nm.

  4. Smarandache Continued Fractions

    OpenAIRE

    Ibstedt, H.

    2001-01-01

    The theory of general continued fractions is developed to the extent required in order to calculate Smarandache continued fractions to a given number of decimal places. Proof is given for the fact that Smarandache general continued fractions built with positive integer Smarandache sequences baving only a finite number of terms equal to 1 is convergent. A few numerical results are given.

  5. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  6. Monodispersed fabrication and dielectric studies on ethylenediamine passivated α-manganese dioxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, A. Martin [Research and Development Centre, Bharathiar University, Coimbatore, Tamilnadu (India); Kumar, R. Thilak, E-mail: manojthilak@yahoo.com [Periyar Arts College, Cuddalore-607001, Tamilnadu (India)

    2016-09-15

    Highlights: • Monodispersed ethylenediamine (EDA) passivated α-MnO{sub 2} nanorods were fabricated by inexpensive wet chemical method. • FTIR analysis indicated that surface passivation is strongly influenced by the introduction of the organic ligand. • XRD and HR-SEM revealed the structure and morphology of the fabricated α-MnO{sub 2} nanorods with an average size of about 40 × 200 nm. • Dielectric studies pointed out that the fabricated α-MnO{sub 2} is semiconducting in nature with resistivity, ρ = 1.46 to 5.76 × 10{sup 3} Ωcm. • The optical energy gap for the fabricated α-MnO{sub 2} nanorods is found to be around 1.37 eV. - Abstract: In this present work, pure α-MnO{sub 2} nanorods were fabricated by the reduction of 0.2 m/L of KMnO{sub 4} with 0.2 m/L of Na{sub 2}S{sub 2}O{sub 3}·5H{sub 2}O and by passivating with the organic ligand Ethylenediamine (EDA). The structural, functional, morphological and chemical composition of the nanorods were investigated by X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectrometer (FTIR), High Resolution Scanning Electron Microscope (HR-SEM) and Energy Dispersive X-Ray Spectrometry (EDX). The XRD analysis indicated high crystalline nature of the product and FTIR confirmed the contribution of the organic ligand in surface passivation. HR-SEM image revealed the morphology of the α-MnO{sub 2} nanorods with an average size of about 40 × 200 nm. EDX confirmed the presence of Mn and O in the material. UV–visible spectrophotometery was used to determine the absorption behavior of the nanorods and an indirect band gap of 1.37 eV was acquired by Taucplot. Dielectric studies were carried out using Broadband Dielectric Spectrometer(BDS) and the resistivity was found to be around the semiconductor range (ρ = 1.46 to 5.76 × 10{sup 3} Ωcm).

  7. Fractional smith chart theory

    KAUST Repository

    Shamim, Atif

    2011-03-01

    For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach. © 2010 IEEE.

  8. Spatiotemporal Fractionation Schemes for Irradiating Large Cerebral Arteriovenous Malformations

    Energy Technology Data Exchange (ETDEWEB)

    Unkelbach, Jan, E-mail: junkelbach@mgh.harvard.edu [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Bussière, Marc R. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States); Chapman, Paul H. [Department of Neurosurgery, Massachusetts General Hospital, Boston, Massachusetts (United States); Loeffler, Jay S.; Shih, Helen A. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts (United States)

    2016-07-01

    Purpose: To optimally exploit fractionation effects in the context of radiosurgery treatments of large cerebral arteriovenous malformations (AVMs). In current practice, fractionated treatments divide the dose evenly into several fractions, which generally leads to low obliteration rates. In this work, we investigate the potential benefit of delivering distinct dose distributions in different fractions. Methods and Materials: Five patients with large cerebral AVMs were reviewed and replanned for intensity modulated arc therapy delivered with conventional photon beams. Treatment plans allowing for different dose distributions in all fractions were obtained by performing treatment plan optimization based on the cumulative biologically effective dose delivered at the end of treatment. Results: We show that distinct treatment plans can be designed for different fractions, such that high single-fraction doses are delivered to complementary parts of the AVM. All plans create a similar dose bath in the surrounding normal brain and thereby exploit the fractionation effect. This partial hypofractionation in the AVM along with fractionation in normal brain achieves a net improvement of the therapeutic ratio. We show that a biological dose reduction of approximately 10% in the healthy brain can be achieved compared with reference treatment schedules that deliver the same dose distribution in all fractions. Conclusions: Boosting complementary parts of the target volume in different fractions may provide a therapeutic advantage in fractionated radiosurgery treatments of large cerebral AVMs. The strategy allows for a mean dose reduction in normal brain that may be valuable for a patient population with an otherwise normal life expectancy.

  9. Fractional factorial plans

    CERN Document Server

    Dey, Aloke

    2009-01-01

    A one-stop reference to fractional factorials and related orthogonal arrays.Presenting one of the most dynamic areas of statistical research, this book offers a systematic, rigorous, and up-to-date treatment of fractional factorial designs and related combinatorial mathematics. Leading statisticians Aloke Dey and Rahul Mukerjee consolidate vast amounts of material from the professional literature--expertly weaving fractional replication, orthogonal arrays, and optimality aspects. They develop the basic theory of fractional factorials using the calculus of factorial arrangements, thereby providing a unified approach to the study of fractional factorial plans. An indispensable guide for statisticians in research and industry as well as for graduate students, Fractional Factorial Plans features: * Construction procedures of symmetric and asymmetric orthogonal arrays. * Many up-to-date research results on nonexistence. * A chapter on optimal fractional factorials not based on orthogonal arrays. * Trend-free plans...

  10. Fractional Dynamics and Control

    CERN Document Server

    Machado, José; Luo, Albert

    2012-01-01

    Fractional Dynamics and Control provides a comprehensive overview of recent advances in the areas of nonlinear dynamics, vibration and control with analytical, numerical, and experimental results. This book provides an overview of recent discoveries in fractional control, delves into fractional variational principles and differential equations, and applies advanced techniques in fractional calculus to solving complicated mathematical and physical problems.Finally, this book also discusses the role that fractional order modeling can play in complex systems for engineering and science. Discusses how fractional dynamics and control can be used to solve nonlinear science and complexity issues Shows how fractional differential equations and models can be used to solve turbulence and wave equations in mechanics and gravity theories and Schrodinger’s equation  Presents factional relaxation modeling of dielectric materials and wave equations for dielectrics  Develops new methods for control and synchronization of...

  11. Preparation of monodisperse curcumin-imprinted polymer by precipitation polymerization and its application for the extraction of curcuminoids from Curcuma longa L.

    Science.gov (United States)

    Kitabatake, Tomoko; Tabo, Hiromi; Matsunaga, Hisami; Haginaka, Jun

    2013-08-01

    A monodisperse molecularly imprinted polymer (MIP) for curcumin was first prepared by precipitation polymerization using methacrylamide (MAM) and 4-vinylpyridine as functional co-monomers, divinylbenzene as a crosslinker, and a mixture of acetonitrile and toluene as a porogen. The use of MAM as the co-monomer resulted in the formation of a monodisperse MIP and non-imprinted polymer (NIP). MIP and NIP, respectively, were monodispersed with a narrow particle size distribution (3.3 ± 0.09 and 3.5 ± 0.10 μm). In addition to shape recognition, hydrophobic and hydrogen-bonding interactions affected the retention and molecular-recognition of curcumin on the MIP. The MIP for curcumin could extract curcuminoids (curcumin, demethoxycurcumin, and bisdemethoxycurcumin) in Curcuma longa L.

  12. High surface area monodispersed Fe3O4 nanoparticles alone and on physical exfoliated graphite for improved supercapacitors

    Science.gov (United States)

    Sarno, Maria; Ponticorvo, Eleonora; Cirillo, Claudia

    2016-12-01

    Highly conductive, unsophisticated and easy to be obtained physical exfoliated graphite (PHG) supporting well dispersed magnetite, Fe3O4/PHG nanocomposite, has been prepared by a one-step chemical strategy and physico-chemical characterized. The nanocomposite, favoured by the a-polar nanoparticles (NPs) capping, results in a self-assembled monolayer of monodispersed Fe3O4, covering perfectly the hydrophobic surfaces of PHG. The nanocomposite as an electrode material was fabricated into a supercapacitor and characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. It shows, after a suitable annealing, significant electrochemical properties (capacitance value of 787 F/g at 0.5 A g-1 and a Fe3O4/PHG weight ratio of 0.31) and good cycling stability (retention 91% after 30,000 cycles). Highly monodispersed very fine Fe3O4 NPs, covered by organic chains, have been also synthesized. The high surface area Fe3O4 NPs, after washing to leave a low content of organic chains able to avoid aggregation without excessively affecting the electrical properties of the material, exhibit remarkable pseudocapacitive activities, including the highest specific capacitance over reported for Fe3O4 (300 F/g at 0.5 A g-1).

  13. Seedless Synthesis of Monodispersed Gold Nanorods with Remarkably High Yield: Synergistic Effect of Template Modification and Growth Kinetics Regulation.

    Science.gov (United States)

    Liu, Kang; Bu, Yanru; Zheng, Yuanhui; Jiang, Xuchuan; Yu, Aibing; Wang, Huanting

    2017-03-08

    Gold nanorods (AuNRs) are versatile materials due to their broadly tunable optical properties associated with their anisotropic feature. Conventional seed-mediated synthesis is, however, not only limited by the operational complexity and over-sensitivity towards subtle changes of experimental conditions but also suffers from low yield (≈15 %). A facile seedless method is reported to overcome these challenges. Monodispersed AuNRs with high yield (≈100 %) and highly adjustable longitudinal surface plasmon resonance (LSPR) are reproducibly synthesized. The parameters that influence the AuNRs growth were thoroughly investigated in terms of growth kinetics and soft-template regulation, offering a better understanding of the template-based mechanism. The facile synthesis, broad tunability of LSRP, high reproducibility, high yield, and ease of scale-up make this method promising for the future mass production of monodispersed AuNRs for applications in catalysis, sensing, and biomedicine. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Response of three instruments devoted to surface-area for monodisperse and polydisperse aerosols in molecular and transition regimes

    International Nuclear Information System (INIS)

    Bau, Sebastien; Witschger, Olivier; Gensdarmes, Francois; Thomas, Dominique

    2011-01-01

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment. Indeed, our understanding of the hazards, the actual exposures in the workplace and the limits of engineering controls and personal protective equipment with regard to NP are still under development. Several studies have already identified surface-area as an important determinant of low solubility nanoparticles toxicity. As a consequence, the concept that surface-area could be a relevant metric for characterizing exposure to low solubility airborne NP has been proposed [1]. To provide NP surface-area concentration, some direct-reading instruments have been designed, based on diffusion charging. The actual available instruments providing airborne NP surface-area concentration are studied in this work: LQ1-DC (Matter Engineering), AeroTrak T M 9000 (TSI) and NSAM (TSI model 3550). Their performances regarding monodisperse carbon NP have been investigated by Bau et al.. This work aims at completing the instruments characterization regarding monodisperse NP of other chemical composition (aluminium, copper, silver) and studying their performances against polydisperse aerosols of NP.

  15. Facile preparation and visible light photocatalytic activity of CdIn2S4 monodispersed spherical particles

    International Nuclear Information System (INIS)

    Mu Jin; Wei Qinglian; Yao Pingping; Zhao Xueling; Kang Shizhao; Li Xiangqing

    2012-01-01

    Highlights: ► CdIn 2 S 4 monodispersed spherical particles were prepared by a soft solution method. ► Mercaptoacetic acid was used as capping agent to hinder the fast crystal growth. ► Thioacetamide as sulfur source resulted in the slow growth of particles. ► CdIn 2 S 4 spheres showed high visible light photocatalytic activity. - Abstract: We developed a facile method to prepare CdIn 2 S 4 monodispersed spherical particles by using mercaptoacetic acid as capping agent and thioacetamide as sulfur source. The results indicated that the size and morphology of CdIn 2 S 4 particles were related to reaction time. The CdIn 2 S 4 spherical particles with an average size of about 236 nm and a narrow size distribution were formed after reacting for 7 h. The photocatalytic activity of as-synthesized CdIn 2 S 4 spherical particles was evaluated by the photocatalytic degradation of methyl orange under visible light illumination. The results showed that the photocatalytic activity increased with prolonging reaction time in the preparation of CdIn 2 S 4 spherical particles. The CdIn 2 S 4 spherical particles prepared after reacting for 7 h exhibited a 98% degradation efficiency of methyl orange after 15 min visible light irradiation.

  16. Synthesis of monodisperse silica microspheres and modification with diazoresin for mixed-mode ultra high performance liquid chromatography separations.

    Science.gov (United States)

    Cong, Hailin; Yu, Bing; Tian, Chao; Zhang, Shuai; Yuan, Hua

    2017-11-01

    Monodisperse silica particles with average diameters of 1.9-2.9 μm were synthesized by a modified Stöber method, in which tetraethyl orthosilicate was continuously supplied to the reaction mixture containing KCl electrolyte, water, ethanol, and ammonia. The obtained silica particles were modified by self-assembly with positively charged photosensitive diazoresin on the surface. After treatment with ultraviolet light, the ionic bonding between silica and diazoresin was converted into covalent bonding through a unique photochemistry reaction of diazoresin. Depending on the chemical structure of diazoresin and mobile phase composition, the diazoresin-modified silica stationary phase showed different separation mechanisms, including reversed phase and hydrophilic interactions. Therefore, a variety of baseline separation of benzene analogues and organic acids was achieved by using the diazoresin-modified silica particles as packing materials in ultra high performance liquid chromatography. According to the π-π interactional difference between carbon rings of fullerenes and benzene rings of diazoresin, C 60 and C 70 were also well separated by ultra-high performance liquid chromatography. Because it has a small size, the ∼2.5 μm monodisperse diazoresin-modified silica stationary phase shows ultra-high efficiency compared with the commercial C 18 -silica high-performance liquid chromatography stationary phase with average diameters of ∼5 μm. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Synthesis and characterization of monodispersed orthorhombic manganese oxide nanoparticles produced by Bacillus sp. cells simultaneous to its bioremediation

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Arvind [Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016 (India); Singh, Vidya Nand; Mehta, Bodh Raj [Thin Film Laboratory, Department of Physics, Indian Institute of Technology, Delhi Hauz Khas, New Delhi 110016 (India); Khare, Sunil Kumar, E-mail: skhare@rocketmail.com [Enzyme and Microbial Biochemistry Laboratory, Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110 016 (India)

    2011-08-30

    Highlights: {yields} An efficient process wherein remediated manganese is synthesized into nanoparticles. {yields} A microbial process for manganese nanoparticle synthesis from metal waste streams. {yields} Nanoparticles characterized as monodispersed, spherical and 4.62 {+-} 0.14 nm sized MnO{sub 2}. -- Abstract: A heavy metal resistant strain of Bacillus sp. (MTCC10650) is reported. The strain exhibited the property of bioaccumulating manganese, simultaneous to its remediation. The nanoparticles thus formed were characterized and identified using energy dispersive X-ray analysis (EDAX), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD) and atomic force microscopy (AFM). When the cells were challenged with manganese, the cells effectively synthesized nanoparticles of average size 4.62 {+-} 0.14 nm. These were mostly spherical and monodispersed. The ex situ enzymatically synthesized nanoparticles exhibited an absorbance maximum at 329 nm. These were more discrete, small and uniform, than the manganese oxide nanoparticles recovered after cell sonication. The use of Bacillus sp. cells seems promising and advantageous approach. Since, it serves dual purposes of (i) remediation and (ii) nanoparticle synthesis. Considering the increasing demand of developing environmental friendly and cost effective technologies for nanoparticle synthesis, these cells can be exploited for the remediation of manganese from the environment in conjunction with development of a greener process for the controlled synthesis of manganese oxide nanoparticles.

  18. Microfluidic preparation and self diffusion PFG-NMR analysis of monodisperse water-in-oil-in-water double emulsions.

    Science.gov (United States)

    Hughes, Eric; Maan, Abid Aslam; Acquistapace, Simone; Burbidge, Adam; Johns, Michael L; Gunes, Deniz Z; Clausen, Pascal; Syrbe, Axel; Hugo, Julien; Schroen, Karin; Miralles, Vincent; Atkins, Tim; Gray, Richard; Homewood, Philip; Zick, Klaus

    2013-01-01

    Monodisperse water-in-oil-in-water (WOW) double emulsions have been prepared using microfluidic glass devices designed and built primarily from off the shelf components. The systems were easy to assemble and use. They were capable of producing double emulsions with an outer droplet size from 100 to 40 μm. Depending on how the devices were operated, double emulsions containing either single or multiple water droplets could be produced. Pulsed-field gradient self-diffusion NMR experiments have been performed on the monodisperse water-in-oil-in-water double emulsions to obtain information on the inner water droplet diameter and the distribution of the water in the different phases of the double emulsion. This has been achieved by applying regularization methods to the self-diffusion data. Using these methods the stability of the double emulsions to osmotic pressure imbalance has been followed by observing the change in the size of the inner water droplets over time. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Self-charging of 198Au-labeled monodisperse gold aerosols studied with a miniature electrical mobility spectrometer

    International Nuclear Information System (INIS)

    Yeh, H.C.; Newton, G.J.; Raabe, O.G.; Boor, D.R.

    1976-01-01

    Knowledge of the electrostatic character of an aerosol may be essential in assessing its potential inhalation hazard. In inhalation studies with radioactive aerosols, the aerosol charge state may change in the course of transport due to the emission of α, β or γ radiations. This paper describes an experimental study of the self-charging of 198 Au-labeled aerosols of monodisperse gold spheres by β emission. A miniature aerosol electrical mobility spectrometer, suitable for use in inhalation studies with radioactive aerosols, was developed and used in this study. This device is relatively inexpensive, easy to manufacture and its contamination by radioactive material has been minimized. Using polystyrene latex spheres, ranging in diameter from 0.176 to 1.18 μm, the spectrometer was calibrated with flow rates ranging from 400 to 4800 ml/min. Experiments with two sizes of 198 Au-labeled monodisperse gold aerosols were performed. Results indicate that the radioactivity of an aerosol can cause self-charging and affect the charge distribution. (author)

  20. Controllable synthesis and upconversion emission of ultrasmall near-monodisperse lanthanide-doped Sr2LaF7 nanocrystals

    International Nuclear Information System (INIS)

    Mao, Yifu; Ma, Mo; Gong, Lunjun; Xu, Changfu; Ren, Guozhong; Yang, Qibin

    2014-01-01

    Highlights: • Apropos NaOH content facilitates the growth of pure phase Sr 2 LaF 7 NCs. • Yb 3+ doping is favorable to the formation of Sr 2 LaF 7 NCs with uniform size. • Ultrasmall near-monodispersed Sr 2 LaF 7 NCs(sub-10 nm) were synthesized for the first time. • Intense multicolor upconversion can be obtained by properly lanthanide doping. - Abstract: Fluorite phase Sr 2 LaF 7 nanocrystals (NCs) were synthesized via solvothermal method using oleic acid as capping ligands. The effects of preparing conditions on the phase structure, crystal size, morphology, and upconversion (UC) emission properties of the products were studied. The results reveal that just apropos NaOH content facilitates the growth of near-monodispersed pure phase Sr 2 LaF 7 NCs, and Yb 3+ doping is favorable to the formation of pure Sr 2 LaF 7 phase with more uniform size distribution. The average crystalline size of the products can be controlled less than 10 nm. Following appropriate lanthanide ions doping, the NCs show intense blue, yellow, and white-color UC emission under the excitation of a 980 nm laser. The energy transfer UC mechanisms for the fluorescent intensity were also investigated

  1. Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

    KAUST Repository

    Li, Cheng Chao; Dou, Jian; Chen, Luwei; Lin, Jianyi; Zeng, Hua Chun

    2012-01-01

    We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Antisolvent Precipitation for the Synthesis of Monodisperse Mesoporous Niobium Oxide Spheres as Highly Effective Solid Acid Catalysts

    KAUST Repository

    Li, Cheng Chao

    2012-03-20

    We have developed a low-cost reaction protocol to synthesize mesoporous Nb 2O 5-based solid acid catalysts with external shape control. In the synthesis, monodisperse glycolated niobium oxide spheres (GNOS) were prepared by means of a simple antisolvent precipitation approach and subsequently converted to mesoporous niobium oxide spheres (MNOS) with a large surface area of 312m 2g -1 by means of the hydrothermal treatment. The antisolvent acetone used to obtain GNOS was recovered through distillation at high purity. The obtained mesoporous MNOS were functionalized further with sulfate anions at different temperatures or incorporated with tungstophosphoric acid to obtain recyclable solid acid catalysts. These MNOS-based catalysts showed excellent performance in a wide range of acid-catalyzed reactions, such as Friedel-Crafts alkylation, esterification, and hydrolysis of acetates. As they are monodisperse spheres with diameters in the submicrometer range, the catalysts can be easily separated and reused. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Synthesis and characterization of monodispersed orthorhombic manganese oxide nanoparticles produced by Bacillus sp. cells simultaneous to its bioremediation

    International Nuclear Information System (INIS)

    Sinha, Arvind; Singh, Vidya Nand; Mehta, Bodh Raj; Khare, Sunil Kumar

    2011-01-01

    Highlights: → An efficient process wherein remediated manganese is synthesized into nanoparticles. → A microbial process for manganese nanoparticle synthesis from metal waste streams. → Nanoparticles characterized as monodispersed, spherical and 4.62 ± 0.14 nm sized MnO 2 . -- Abstract: A heavy metal resistant strain of Bacillus sp. (MTCC10650) is reported. The strain exhibited the property of bioaccumulating manganese, simultaneous to its remediation. The nanoparticles thus formed were characterized and identified using energy dispersive X-ray analysis (EDAX), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD) and atomic force microscopy (AFM). When the cells were challenged with manganese, the cells effectively synthesized nanoparticles of average size 4.62 ± 0.14 nm. These were mostly spherical and monodispersed. The ex situ enzymatically synthesized nanoparticles exhibited an absorbance maximum at 329 nm. These were more discrete, small and uniform, than the manganese oxide nanoparticles recovered after cell sonication. The use of Bacillus sp. cells seems promising and advantageous approach. Since, it serves dual purposes of (i) remediation and (ii) nanoparticle synthesis. Considering the increasing demand of developing environmental friendly and cost effective technologies for nanoparticle synthesis, these cells can be exploited for the remediation of manganese from the environment in conjunction with development of a greener process for the controlled synthesis of manganese oxide nanoparticles.

  4. Response of three instruments devoted to surface-area for monodisperse and polydisperse aerosols in molecular and transition regimes

    Energy Technology Data Exchange (ETDEWEB)

    Bau, Sebastien; Witschger, Olivier [Institut National de Recherche et de Securite (INRS), Laboratoire de Metrologie des Aerosols, Rue du Morvan, CS 60027, 54519 Vandoeuvre Cedex (France); Gensdarmes, Francois [Institut de Radioprotection et de Surete Nucleaire (IRSN), Laboratoire de Physique et de Metrologie des Aerosols, BP 68, 91192 Gif-sur-Yvette (France); Thomas, Dominique, E-mail: sebastien.bau@inrs.fr [Laboratoire Reactions et Genie des Procedes (LRGP), groupe SAFE, 1 rue Grandville, BP 20041, 54001 Nancy Cedex (France)

    2011-07-06

    An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment. Indeed, our understanding of the hazards, the actual exposures in the workplace and the limits of engineering controls and personal protective equipment with regard to NP are still under development. Several studies have already identified surface-area as an important determinant of low solubility nanoparticles toxicity. As a consequence, the concept that surface-area could be a relevant metric for characterizing exposure to low solubility airborne NP has been proposed [1]. To provide NP surface-area concentration, some direct-reading instruments have been designed, based on diffusion charging. The actual available instruments providing airborne NP surface-area concentration are studied in this work: LQ1-DC (Matter Engineering), AeroTrak{sup TM} 9000 (TSI) and NSAM (TSI model 3550). Their performances regarding monodisperse carbon NP have been investigated by Bau et al.. This work aims at completing the instruments characterization regarding monodisperse NP of other chemical composition (aluminium, copper, silver) and studying their performances against polydisperse aerosols of NP.

  5. Hypo fractionated radiotherapy in advanced lung cancer

    International Nuclear Information System (INIS)

    Andrade Carvalho, Heloisa de; Saito, Newton Heitetsu; Gomes, Herbeni Cardoso; Aguilar, Patricia Bailao; Nadalin, Wladimir

    1996-01-01

    Patients with advanced lung cancers have bad prognosis and, many times, are submitted to prolonged and not always efficient treatments. We present a study where 51 patients were treated with hypo fractionated radiotherapy, based on two distinct schemes, according to the performance status and social conditions of each patient: continuous treatment: 30 Gy, 10 fractions of 3 Gy, 5 days/week (37 cases); weekly treatment: 30 Gy, 6 fractions of 5 Gy, once a week (14 cases). Symptoms relief and impact in survival were evaluated. In both groups, we observed improvement of symptoms in about 70% of the occurrences with a medium survival of three months. We conclude that hypo fractionation is an effective palliative treatment for lung cancers, in patients with short life-expectancy and must be considered as a option in advanced cases, in patients with short life-expectancy that deserve some kind of treatment. (author). 37 refs., 2 tabs

  6. Dividing Fractions: A Pedagogical Technique

    Science.gov (United States)

    Lewis, Robert

    2016-01-01

    When dividing one fraction by a second fraction, invert, that is, flip the second fraction, then multiply it by the first fraction. To multiply fractions, simply multiply across the denominators, and multiply across the numerators to get the resultant fraction. So by inverting the division of fractions it is turned into an easy multiplication of…

  7. Fractional distillation of oil

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L D

    1931-10-31

    A method of dividing oil into lubricating oil fractions without substantial cracking by introducing the oil in a heated state into a fractionating column from which oil fractions having different boiling points are withdrawn at different levels, while reflux liquid is supplied to the top of the column, and additional heat is introduced into the column by contacting with the oil therein a heated fluid of higher monlecular weight than water and less susceptible to thermal decomposition than is the highest boiling oil fraction resulting from the distillation, or of which any products produced by thermal decomposition will not occur in the highest boiling distillate withdrawn from the column.

  8. Crystallisation and structural studies of monodisperse nylon oligomers and related polymers

    International Nuclear Information System (INIS)

    Sikorski, P.T.

    2001-11-01

    Using electron and X-ray diffraction data, together with computerised molecular modeling, the structures of monodisperse nylon oligomers and related polymers have been investigated. Structural changes on heating were also studied. The molecules were crystallised from solution and their morphologies examined using optical and transmission electron microscopy. Lath-like lamellar crystals of the polyester poly-β-propiolactone were crystallised isothermally. The interpretation of the diffraction data with the use of molecular modeling led to the discovery of the new crystalline structure, the γ-structure. In the γ-structure, the polyester chain is in an all-trans conformation and the structure consists of a two-chain, basal-faced, orthorhombic unit cell. The setting angles, with respect to the a axis, are ± 51.5 deg for the corner and centre chains, respectively. The lamellae are 5 nm in thickness and the chains run orthogonal to the lamellar surface. The general fold direction is along the a-axis (long axis of the crystal) and the chain folds successively in the [110] and [11-bar0] directions. Three different nylon 4 6 oligomers were crystallised from solution using a range of crystallisation methods. The 4- and 8-amide molecules were found to form three-dimensional crystals, in which the crystal thickness was much greater than the molecular length. The structure was found to be different from the nylon 4 6 polymer reported previously. It was found that the type of hydrogen-bonded sheet formed by these molecules can influence the way in which these sheets stack to form crystals. In addition, a study of the 9-amide molecule showed that a particular type of hydrogen-bonded sheet, a-sheet, is preferred for nylon 4 6. This discovery suggests that an amide unit is found in the fold in the chain-folded nylon 4 6 polymer crystals, to allow the a-sheets to be formed. It is not a consequence of a need to form a stress-free fold. In the regular adjacent re-entry chain

  9. Toxicity of inhaled 238PuO2 in Beagle dogs: A. Monodisperse 1.5 μm AMAD particles. B. Monodisperse 3.0 μm particles. XV

    International Nuclear Information System (INIS)

    Mewhinney, J.A.; Gillett, N.A.; Muggenburg, B.A.; Hahn, F.F.; Diel, J.H.; Mauderly, J.L.; Boecker, B.B.; McClellan, R.O.

    1988-01-01

    Beagle dogs inhaled one of two sizes of monodisperse aerosols of 238 PuO 2 that resulted in graded levels of 238 Pu in the lung. All dogs are being studied for their life span. One hundred and thirty-seven dogs that had initial lung burdens ranging from 0.01 to 1.5 μCi 238 Pu/kg body weight (0.37 to 56 kBq/kg) have died, 8 with radiation pneumonitis and pulmonary fibrosis, 8 with lung tumors, 88 with bone tumors, 10 with liver tumors, and 25 of miscellaneous causes. Eighteen control dogs have died. Observations are being continued on 8 exposed and 6 control dogs alive at 4577-5274 days after exposure. (author)

  10. Toxicity of inhaled {sup 238}PuO{sub 2} in Beagle dogs: A. Monodisperse 1.5 {mu}m AMAD particles. B. Monodisperse 3.0 {mu}m particles. XV

    Energy Technology Data Exchange (ETDEWEB)

    Mewhinney, J A; Gillett, N A; Muggenburg, B A; Hahn, F F; Diel, J H; Mauderly, J L; Boecker, B B; McClellan, R O

    1988-12-01

    Beagle dogs inhaled one of two sizes of monodisperse aerosols of {sup 238}PuO{sub 2} that resulted in graded levels of {sup 238}Pu in the lung. All dogs are being studied for their life span. One hundred and thirty-seven dogs that had initial lung burdens ranging from 0.01 to 1.5 {mu}Ci {sup 238}Pu/kg body weight (0.37 to 56 kBq/kg) have died, 8 with radiation pneumonitis and pulmonary fibrosis, 8 with lung tumors, 88 with bone tumors, 10 with liver tumors, and 25 of miscellaneous causes. Eighteen control dogs have died. Observations are being continued on 8 exposed and 6 control dogs alive at 4577-5274 days after exposure. (author)

  11. Counselor Identity: Conformity or Distinction?

    Science.gov (United States)

    McLaughlin, Jerry E.; Boettcher, Kathryn

    2009-01-01

    The authors explore 3 debates in other disciplines similar to counseling's identity debate in order to learn about common themes and outcomes. Conformity, distinction, and cohesion emerged as common themes. They conclude that counselors should retain their distinctive, humanistic approach rather than conforming to the dominant, medical approach.

  12. Fractional Poisson process (II)

    International Nuclear Information System (INIS)

    Wang Xiaotian; Wen Zhixiong; Zhang Shiying

    2006-01-01

    In this paper, we propose a stochastic process W H (t)(H-bar (12,1)) which we call fractional Poisson process. The process W H (t) is self-similar in wide sense, displays long range dependence, and has more fatter tail than Gaussian process. In addition, it converges to fractional Brownian motion in distribution

  13. An Appetite for Fractions

    Science.gov (United States)

    Wilkerson, Trena L.; Bryan, Tommy; Curry, Jane

    2012-01-01

    This article describes how using candy bars as models gives sixth-grade students a taste for learning to represent fractions whose denominators are factors of twelve. Using paper models of the candy bars, students explored and compared fractions. They noticed fewer different representations for one-third than for one-half. The authors conclude…

  14. Can Kindergartners Do Fractions?

    Science.gov (United States)

    Cwikla, Julie

    2014-01-01

    Mathematics professor Julie Cwikla decided that she needed to investigate young children's understandings and see what precurricular partitioning notions young minds bring to the fraction table. Cwikla realized that only a handful of studies have examined how preschool-age and early elementary school-age students solve fraction problems (Empson…

  15. Fractional bosonic strings

    Science.gov (United States)

    Diaz, Victor Alfonzo; Giusti, Andrea

    2018-03-01

    The aim of this paper is to present a simple generalization of bosonic string theory in the framework of the theory of fractional variational problems. Specifically, we present a fractional extension of the Polyakov action, for which we compute the general form of the equations of motion and discuss the connection between the new fractional action and a generalization the Nambu-Goto action. Consequently, we analyze the symmetries of the modified Polyakov action and try to fix the gauge, following the classical procedures. Then we solve the equations of motion in a simplified setting. Finally, we present a Hamiltonian description of the classical fractional bosonic string and introduce the fractional light-cone gauge. It is important to remark that, throughout the whole paper, we thoroughly discuss how to recover the known results as an "integer" limit of the presented model.

  16. Influence of the vibration source location on the modes of jet disintegration in the priller and on monodispersity of the finished product

    OpenAIRE

    Skydanenko, Maksym; Kononenko, Mykola; Kurdes, Yuliia

    2017-01-01

    Influence of the vibration source location on the modes of liquid jets disintegration and obtaining monodisperse droplets and granules of the finished product is theoretically grounded and experimentally confirmed. The experiment was conducted on an experimental stand of industrial granulation equipment.

  17. Monodisperse Water-in-Oil-in-Water (W/O/W Double Emulsion Droplets as Uniform Compartments for High-Throughput Analysis via Flow Cytometry

    Directory of Open Access Journals (Sweden)

    Jing Yan

    2013-12-01

    Full Text Available Here we report the application of monodisperse double emulsion droplets, produced in a single step within partially hydrophilic/partially hydrophobic microfluidic devices, as defined containers for quantitative flow cytometric analysis. Samples with varying fluorophore concentrations were generated, and a clear correlation between dye concentration and fluorescence signals was observed.

  18. Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

    Directory of Open Access Journals (Sweden)

    Li Xing-Hua

    2010-01-01

    Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

  19. Preparation of size-tunable, highly monodisperse PVP-protected Pt-nanoparticles by seed-mediated growth

    International Nuclear Information System (INIS)

    Koebel, Matthias M.; Jones, Louis C.; Somorjai, Gabor A.

    2008-01-01

    We demonstrate a preparative method which produces highly monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 o C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrrolidone (PVP). Slow addition of the Pt-salt will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8 nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7 nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of larger particles into smaller entities.

  20. Facile preparation of monodisperse, impurity-free, and antioxidation copper nanoparticles on a large scale for application in conductive ink.

    Science.gov (United States)

    Zhang, Yu; Zhu, Pengli; Li, Gang; Zhao, Tao; Fu, Xianzhu; Sun, Rong; Zhou, Feng; Wong, Ching-ping

    2014-01-08

    Monodisperse copper nanoparticles with high purity and antioxidation properties are synthesized quickly (only 5 min) on a large scale (multigram amounts) by a modified polyol process using slightly soluble Cu(OH)2 as the precursor, L-ascorbic acid as the reductant, and PEG-2000 as the protectant. The resulting copper nanoparticles have a size distribution of 135 ± 30 nm and do not suffer significant oxidation even after being stored for 30 days under ambient conditions. The copper nanoparticles can be well-dispersed in an oil-based ink, which can be silk-screen printed onto flexible substrates and then converted into conductive patterns after heat treatment. An optimal electrical resistivity of 15.8 μΩ cm is achieved, which is only 10 times larger than that of bulk copper. The synthesized copper nanoparticles could be considered as a cheap and effective material for printed electronics.

  1. Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

    Directory of Open Access Journals (Sweden)

    C. H. Yang

    2012-01-01

    Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

  2. Direct electron transfer of Cytochrome c at mono-dispersed and negatively charged perylene-graphene matrix.

    Science.gov (United States)

    Zhang, Nan; Lv, Xiangyu; Ma, Weiguang; Hu, Yuwei; Li, Fenghua; Han, Dongxue; Niu, Li

    2013-03-30

    Mono-dispersed 3,4,9,10-perylene tetracarboxylic acid (PTCA) functionalized graphene sheets (PTCA-graphene) were fabricated by a chemical route and dispersed well in aqueous solution. PTCA-graphene with plenty of -COOH groups as electrostatic absorbing sites were beneficial to the loading of Cytochrome c (Cyt c). Cyt c, which was tightly immobilized on the PTCA-graphene modified glassy carbon electrode, maintained its natural conformation. Direct electron transfer of Cyt c and the electro-catalytic activity towards the reduction of H2O2 were also achieved. It has been substantiated that PTCA-graphene is a preferable biocompatible matrix for Cyt c. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. NOx formation from the combustion of monodisperse n-heptane sprays doped with fuel-nitrogen additives

    Science.gov (United States)

    Sarv, Hamid; Cernansky, Nicholas P.

    1989-01-01

    A series of experiments with simulated synthetic fuels were conducted in order to investigate the effect of droplet size on the conversion of fuel-nitrogen to NOx. Pyridine and pyrrole were added to n-heptane as nitrogen-containing additives and burned as monodisperse fuel droplets under various operating conditions in a spray combustion facility. The experimental results indicate that under stoichiometric and fuel-rich conditions, reducing the droplet size increases the efficiency of fuel-N conversion to NOx. This observation is associated with improved oxidation of the pyrolysis fragments of the additive by better oxygen penetration through the droplet flame zone. The dominant reactions by which fuel-N is transformed to NOx were also considered analytically by a premixed laminar flame code. The calculations are compared to the small droplet size results.

  4. Preparation of submicrometer monodispersed magnetic silica particles using a novel water in oil microemulsion: properties and application for enzyme immobilization.

    Science.gov (United States)

    Tuttolomondo, Maria Victoria; Villanueva, Maria Emilia; Alvarez, Gisela Solange; Desimone, Martín Federico; Díaz, Luis Eduardo

    2013-10-01

    The synthesis of monodispersed magnetic silica nanoparticles (MSN) is described using a water-in-oil reverse microemulsion system that does not require the use of co-surfactants. Sodium silicate, Tween 20 as a neutral surfactant and 1-butanol as the organic phase were used. There are several advantages of the proposed method including a saturation magnetization value of 10 emu/g for the particles obtained, uniformity of size and that they are easily functionalized to bind urease covalently. Moreover, the intra-day, inter-day and long-term stability results confirm that the procedure was successful and the enzyme-linked MSNs were stable over repeated uses and storage retaining more than 75% activity after 4 months.

  5. Rapid Synthesis of Highly Monodisperse Au x Ag 1− x Alloy Nanoparticles via a Half-Seeding Approach

    KAUST Repository

    Chng, Ting Ting

    2011-05-03

    Gold-silver alloy AuxAg1-x is an important class of functional materials promising new applications across a wide array of technological fields. In this paper, we report a fast and facile synthetic protocol for preparation of highly monodisperse AuxAg1-x alloy nanoparticles in the size range of 3-6 nm. The precursors employed in this work are M(I)-alkanethiolates (M = Au and Ag), which can be easily prepared by mixing common chemicals such as HAuCl4 or AgNO3 with alkanethiols at room temperature. In this half-seeding approach, one of the M(I)-alkanethiolates is first heated and reduced in oleylamine solvent, and freshly formed metal clusters will then act as premature seeds on which both the first and second metals (from M(I)-alkanethiolates, M = Au and Ag) can grow accordingly without additional nucleation and thus achieve high monodispersity for product alloy nanoparticles. Unlike in other prevailing methods, both Au and Ag elements present in these solid precursors are in the same monovalent state and have identical supramolecular structures, which may lead to a more homogeneous reduction and complete interdiffusion at elevated reaction temperatures. When the M(I)-alkanethiolates are reduced to metallic forms, the detached alkanethiolate ligands will serve as capping agent to control the growth. More importantly, composition, particle size, and optical properties of AuxAg1-x alloy nanoparticles can be conveniently tuned with this approach. The optical limiting properties of the prepared particles have also been investigated at 532 and 1064 nm using 7 ns laser pulses, which reveals that the as-prepared alloy nanoparticles exhibit outstanding broadband optical limiting properties with low thresholds. © 2011 American Chemical Society.

  6. Synthesis and characterization of monodisperse, mesoporous, and magnetic sub-micron particles doped with a near-infrared fluorescent dye

    International Nuclear Information System (INIS)

    Le Guevel, Xavier; Nooney, Robert; McDonagh, Colette; MacCraith, Brian D.

    2011-01-01

    Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N 2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978 m 2 /g) with 3.40 nm pore diameter and a high fluorescence in the near infrared region at λ=700 nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulated by successfully trapping a hydrophobic ruthenium dye complex inside the particle with an estimated concentration of 3 wt%. Fluorescence imaging confirmed the presence of both NIR dye and the post-grafted ruthenium dye complex inside the particles. These particles moved at approximately 150 μm/s under the influence of a magnetic field, hence demonstrating the multifunctionality and potential for biomedical applications in targeting and imaging. - Graphical Abstract: Hydrophobic fluorescent Ruthenium complex has been loaded into the mesopores as a surrogate drug to simulate drug delivery and to enhance the multifunctionality of the magnetic NIR emitting particles. Highlights: → Monodisperse magnetic mesoporous silica particles emitting in the near infrared region are obtained in one-pot synthesis. → We prove the capacity of such particles to uptake hydrophobic dye to mimic drug loading. → Loaded fluorescent particles can be moved under a magnetic field in a microfluidic

  7. Microfluidic Devices for Blood Fractionation

    Directory of Open Access Journals (Sweden)

    Chwee Teck Lim

    2011-07-01

    Full Text Available Blood, a complex biological fluid, comprises 45% cellular components suspended in protein rich plasma. These different hematologic components perform distinct functions in vivo and thus the ability to efficiently fractionate blood into its individual components has innumerable applications in both clinical diagnosis and biological research. Yet, processing blood is not trivial. In the past decade, a flurry of new microfluidic based technologies has emerged to address this compelling problem. Microfluidics is an attractive solution for this application leveraging its numerous advantages to process clinical blood samples. This paper reviews the various microfluidic approaches realized to successfully fractionate one or more blood components. Techniques to separate plasma from hematologic cellular components as well as isolating blood cells of interest including certain rare cells are discussed. Comparisons based on common separation metrics including efficiency (sensitivity, purity (selectivity, and throughput will be presented. Finally, we will provide insights into the challenges associated with blood-based separation systems towards realizing true point-of-care (POC devices and provide future perspectives.

  8. Fractional Order Generalized Information

    Directory of Open Access Journals (Sweden)

    José Tenreiro Machado

    2014-04-01

    Full Text Available This paper formulates a novel expression for entropy inspired in the properties of Fractional Calculus. The characteristics of the generalized fractional entropy are tested both in standard probability distributions and real world data series. The results reveal that tuning the fractional order allow an high sensitivity to the signal evolution, which is useful in describing the dynamics of complex systems. The concepts are also extended to relative distances and tested with several sets of data, confirming the goodness of the generalization.

  9. Fractional finite Fourier transform.

    Science.gov (United States)

    Khare, Kedar; George, Nicholas

    2004-07-01

    We show that a fractional version of the finite Fourier transform may be defined by using prolate spheroidal wave functions of order zero. The transform is linear and additive in its index and asymptotically goes over to Namias's definition of the fractional Fourier transform. As a special case of this definition, it is shown that the finite Fourier transform may be inverted by using information over a finite range of frequencies in Fourier space, the inversion being sensitive to noise. Numerical illustrations for both forward (fractional) and inverse finite transforms are provided.

  10. Social Trust and Fractionalization:

    DEFF Research Database (Denmark)

    Bjørnskov, Christian

    2008-01-01

    This paper takes a closer look at the importance of fractionalization for the creation of social trust. It first argues that the determinants of trust can be divided into two categories: those affecting individuals' trust radii and those affecting social polarization. A series of estimates using...... a much larger country sample than in previous literature confirms that fractionalization in the form of income inequality and political diversity adversely affects social trust while ethnic diversity does not. However, these effects differ systematically across countries, questioning standard...... interpretations of the influence of fractionalization on trust....

  11. Bidisperse and polydisperse suspension rheology at large solid fraction

    Energy Technology Data Exchange (ETDEWEB)

    Pednekar, Sidhant [Benjamin Levich Institute and Department of Chemical Engineering, The City College of New York, New York, New York 10031; Chun, Jaehun [Pacific Northwest National Laboratory, Richland, Washington 99352; Morris, Jeffrey F. [Benjamin Levich Institute and Department of Chemical Engineering, The City College of New York, New York, New York 10031

    2018-03-01

    At the same solid volume fraction, bidisperse and polydisperse suspensions display lower viscosities, and weaker normal stress response, compared to monodisperse suspensions. The reduction of viscosity associated with size distribution can be explained by an increase of the maximum flowable, or jamming, solid fraction. In this work, concentrated or "dense" suspensions are simulated under strong shearing, where thermal motion and repulsive forces are negligible, but we allow for particle contact with a mild frictional interaction with interparticle friction coefficient of 0.2. Aspects of bidisperse suspension rheology are first revisited to establish that the approach reproduces established trends; the study of bidisperse suspensions at size ratios of large to small particle radii (2 to 4) shows that a minimum in the viscosity occurs for zeta slightly above 0.5, where zeta=phi_{large}/phi is the fraction of the total solid volume occupied by the large particles. The simple shear flows of polydisperse suspensions with truncated normal and log normal size distributions, and bidisperse suspensions which are statistically equivalent with these polydisperse cases up to third moment of the size distribution, are simulated and the rheologies are extracted. Prior work shows that such distributions with equivalent low-order moments have similar phi_{m}, and the rheological behaviors of normal, log normal and bidisperse cases are shown to be in close agreement for a wide range of standard deviation in particle size, with standard correlations which are functionally dependent on phi/phi_{m} providing excellent agreement with the rheology found in simulation. The close agreement of both viscosity and normal stress response between bi- and polydisperse suspensions demonstrates the controlling in influence of the maximum packing fraction in noncolloidal suspensions. Microstructural investigations and the stress distribution according to particle size are also presented.

  12. Distinction

    OpenAIRE

    2010-01-01

    Pr Serge Haroche La Médaille d’or 2009 du CNRS est décernée au Pr Serge Haroche, titulaire de la chaire de Physique quantique depuis 2001. Serge Haroche est spécialiste de physique atomique et d’optique quantique. Il est l’un des fondateurs de l’électrodynamique quantique en cavité, domaine qui permet, par des expériences conceptuellement simples, d’éclairer les fondements de la théorie quantique et de réaliser des prototypes de systèmes de traitement quantique de l’information. Serge Haroche...

  13. Universal signatures of fractionalized quantum critical points.

    Science.gov (United States)

    Isakov, Sergei V; Melko, Roger G; Hastings, Matthew B

    2012-01-13

    Ground states of certain materials can support exotic excitations with a charge equal to a fraction of the fundamental electron charge. The condensation of these fractionalized particles has been predicted to drive unusual quantum phase transitions. Through numerical and theoretical analysis of a physical model of interacting lattice bosons, we establish the existence of such an exotic critical point, called XY*. We measure a highly nonclassical critical exponent η = 1.493 and construct a universal scaling function of winding number distributions that directly demonstrates the distinct topological sectors of an emergent Z(2) gauge field. The universal quantities used to establish this exotic transition can be used to detect other fractionalized quantum critical points in future model and material systems.

  14. Coherent transmutation of electrons into fractionalized anyons.

    Science.gov (United States)

    Barkeshli, Maissam; Berg, Erez; Kivelson, Steven

    2014-11-07

    Electrons have three quantized properties-charge, spin, and Fermi statistics-that are directly responsible for a vast array of phenomena. Here we show how these properties can be coherently and dynamically stripped from the electron as it enters a certain exotic state of matter known as a quantum spin liquid (QSL). In a QSL, electron spins collectively form a highly entangled quantum state that gives rise to the fractionalization of spin, charge, and statistics. We show that certain QSLs host distinct, topologically robust boundary types, some of which allow the electron to coherently enter the QSL as a fractionalized quasi-particle, leaving its spin, charge, or statistics behind. We use these ideas to propose a number of universal, conclusive experimental signatures that would establish fractionalization in QSLs. Copyright © 2014, American Association for the Advancement of Science.

  15. FRACTIONS: CONCEPTUAL AND DIDACTIC ASPECTS

    Directory of Open Access Journals (Sweden)

    Sead Rešić

    2016-09-01

    Full Text Available Fractions represent the manner of writing parts of whole numbers (integers. Rules for operations with fractions differ from rules for operations with integers. Students face difficulties in understanding fractions, especially operations with fractions. These difficulties are well known in didactics of Mathematics throughout the world and there is a lot of research regarding problems in learning about fractions. Methods for facilitating understanding fractions have been discovered, which are essentially related to visualizing operations with fractions.

  16. Fractional Stochastic Field Theory

    Science.gov (United States)

    Honkonen, Juha

    2018-02-01

    Models describing evolution of physical, chemical, biological, social and financial processes are often formulated as differential equations with the understanding that they are large-scale equations for averages of quantities describing intrinsically random processes. Explicit account of randomness may lead to significant changes in the asymptotic behaviour (anomalous scaling) in such models especially in low spatial dimensions, which in many cases may be captured with the use of the renormalization group. Anomalous scaling and memory effects may also be introduced with the use of fractional derivatives and fractional noise. Construction of renormalized stochastic field theory with fractional derivatives and fractional noise in the underlying stochastic differential equations and master equations and the interplay between fluctuation-induced and built-in anomalous scaling behaviour is reviewed and discussed.

  17. Discrete fractional calculus

    CERN Document Server

    Goodrich, Christopher

    2015-01-01

    This text provides the first comprehensive treatment of the discrete fractional calculus. Experienced researchers will find the text useful as a reference for discrete fractional calculus and topics of current interest. Students who are interested in learning about discrete fractional calculus will find this text to provide a useful starting point. Several exercises are offered at the end of each chapter and select answers have been provided at the end of the book. The presentation of the content is designed to give ample flexibility for potential use in a myriad of courses and for independent study. The novel approach taken by the authors includes a simultaneous treatment of the fractional- and integer-order difference calculus (on a variety of time scales, including both the usual forward and backwards difference operators). The reader will acquire a solid foundation in the classical topics of the discrete calculus while being introduced to exciting recent developments, bringing them to the frontiers of the...

  18. Fractional smith chart theory

    KAUST Repository

    Shamim, Atif; Radwan, Ahmed Gomaa; Salama, Khaled N.

    2011-01-01

    matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach. © 2010 IEEE.

  19. Fractional Brownian motion and motion governed by the fractional Langevin equation in confined geometries.

    Science.gov (United States)

    Jeon, Jae-Hyung; Metzler, Ralf

    2010-02-01

    Motivated by subdiffusive motion of biomolecules observed in living cells, we study the stochastic properties of a non-Brownian particle whose motion is governed by either fractional Brownian motion or the fractional Langevin equation and restricted to a finite domain. We investigate by analytic calculations and simulations how time-averaged observables (e.g., the time-averaged mean-squared displacement and displacement correlation) are affected by spatial confinement and dimensionality. In particular, we study the degree of weak ergodicity breaking and scatter between different single trajectories for this confined motion in the subdiffusive domain. The general trend is that deviations from ergodicity are decreased with decreasing size of the movement volume and with increasing dimensionality. We define the displacement correlation function and find that this quantity shows distinct features for fractional Brownian motion, fractional Langevin equation, and continuous time subdiffusion, such that it appears an efficient measure to distinguish these different processes based on single-particle trajectory data.

  20. Fractional laser skin resurfacing.

    Science.gov (United States)

    Alexiades-Armenakas, Macrene R; Dover, Jeffrey S; Arndt, Kenneth A

    2012-11-01

    Laser skin resurfacing (LSR) has evolved over the past 2 decades from traditional ablative to fractional nonablative and fractional ablative resurfacing. Traditional ablative LSR was highly effective in reducing rhytides, photoaging, and acne scarring but was associated with significant side effects and complications. In contrast, nonablative LSR was very safe but failed to deliver consistent clinical improvement. Fractional LSR has achieved the middle ground; it combined the efficacy of traditional LSR with the safety of nonablative modalities. The first fractional laser was a nonablative erbium-doped yttrium aluminum garnet (Er:YAG) laser that produced microscopic columns of thermal injury in the epidermis and upper dermis. Heralding an entirely new concept of laser energy delivery, it delivered the laser beam in microarrays. It resulted in microscopic columns of treated tissue and intervening areas of untreated skin, which yielded rapid reepithelialization. Fractional delivery was quickly applied to ablative wavelengths such as carbon dioxide, Er:YAG, and yttrium scandium gallium garnet (2,790 nm), providing more significant clinical outcomes. Adjustable laser parameters, including power, pitch, dwell time, and spot density, allowed for precise determination of percent surface area, affected penetration depth, and clinical recovery time and efficacy. Fractional LSR has been a significant advance to the laser field, striking the balance between safety and efficacy.

  1. Series expansion in fractional calculus and fractional differential equations

    OpenAIRE

    Li, Ming-Fan; Ren, Ji-Rong; Zhu, Tao

    2009-01-01

    Fractional calculus is the calculus of differentiation and integration of non-integer orders. In a recently paper (Annals of Physics 323 (2008) 2756-2778), the Fundamental Theorem of Fractional Calculus is highlighted. Based on this theorem, in this paper we introduce fractional series expansion method to fractional calculus. We define a kind of fractional Taylor series of an infinitely fractionally-differentiable function. Further, based on our definition we generalize hypergeometric functio...

  2. Toxicity of inhaled 238PuO2 in beagle dogs. A. Monodisperse 1.5 μm 238PuO2. B. Monodisperse 3.0 μm 238PuO2 particles. III

    International Nuclear Information System (INIS)

    Lustgarten, C.S.; Mewhinney, J.A.; Hobbs, C.H.; Halliwell, W.H.; Jones, R.K.; Mauderly, J.L.; McClellan, R.O.; Mo, T.; Pickrell, J.A.

    1976-01-01

    To obtain essential information on the importance of the homogeneity or non-homogeneity of the radiation dose to lung (the hot particle question), Beagle dogs have been exposed to monodisperse aerosols (sigma/sub g/ 238 PuO 2 of either 1.5 μm or 3.0 μm aerodynamic diameter (AD). By using monodisperse particles of these two sizes, the average dose to lung is held constant for a given initial lung burden, but the local alpha dose around the two sizes of particles varies by a factor of about ten. All exposures have been completed with 72 days exposed to each of the two particle sizes of 238 PuO 2 (total of 144 dogs) resulting in graded initial lung burdens which range from .005 to 2.2 μCi/kg of body weight. Twenty-four dogs exposed to the diluent aerosol are serving as controls. The animals will be studied over their total life span. Two exposed dogs have died from pulmonary injury: Dog 710C (with an initial lung burden of 2.0 μCi/kg) died at 631 days after inhalation of 3.0 μm AD aerosol. The cause of death was radiation pneumonitis and pulmonary fibrosis, Dog 746B (with an initial lung burden of 1.3 μCi/kg) died at 791 days after inhalation of 1.5 μm AD aerosol. Death was attributed to intrapulmonic hemorrhage resulting from a degenerative vasculitis. One control dog (721A) was euthanized at 820 days after exposure due to a meningitis and encephalomalacia that caused a severe central nervous system disorder that made the dog difficult to handle.A leukopenia in exposed dogs to date has occurred earlier and to a greater degree in dogs exposed to 3.0 μm AD particles than in dogs that recevied 1.5 μm AD particles. One hundred forty-two exposed and 23 control dogs are surviving at 175 to 1024 days after exposure

  3. FRACTIONS: CONCEPTUAL AND DIDACTIC ASPECTS

    OpenAIRE

    Sead Rešić; Ismet Botonjić; Maid Omerović

    2016-01-01

    Fractions represent the manner of writing parts of whole numbers (integers). Rules for operations with fractions differ from rules for operations with integers. Students face difficulties in understanding fractions, especially operations with fractions. These difficulties are well known in didactics of Mathematics throughout the world and there is a lot of research regarding problems in learning about fractions. Methods for facilitating understanding fractions have been discovered...

  4. Fractional-order devices

    CERN Document Server

    Biswas, Karabi; Caponetto, Riccardo; Mendes Lopes, António; Tenreiro Machado, José António

    2017-01-01

    This book focuses on two specific areas related to fractional order systems – the realization of physical devices characterized by non-integer order impedance, usually called fractional-order elements (FOEs); and the characterization of vegetable tissues via electrical impedance spectroscopy (EIS) – and provides readers with new tools for designing new types of integrated circuits. The majority of the book addresses FOEs. The interest in these topics is related to the need to produce “analogue” electronic devices characterized by non-integer order impedance, and to the characterization of natural phenomena, which are systems with memory or aftereffects and for which the fractional-order calculus tool is the ideal choice for analysis. FOEs represent the building blocks for designing and realizing analogue integrated electronic circuits, which the authors believe hold the potential for a wealth of mass-market applications. The freedom to choose either an integer- or non-integer-order analogue integrator...

  5. Defining poverty as distinctively human

    Directory of Open Access Journals (Sweden)

    H.P.P. Lötter

    2007-05-01

    Full Text Available While it is relatively easy for most people to identify human beings suffering from poverty, it is rather more difficult to come to a proper understanding of poverty. In this article the author wants to deepen our understanding of poverty by interpreting the conventional definitions of poverty in a new light. The article starts with a defence of a claim that poverty is a concept uniquely applicable to humans. It then present a critical discussion of the distinction between absolute and relative poverty and it is then argued that a revision of this distinction can provide general standards applicable to humans everywhere.

  6. Fractional gradient and its application to the fractional advection equation

    OpenAIRE

    D'Ovidio, M.; Garra, R.

    2013-01-01

    In this paper we provide a definition of fractional gradient operators, related to directional derivatives. We develop a fractional vector calculus, providing a probabilistic interpretation and mathematical tools to treat multidimensional fractional differential equations. A first application is discussed in relation to the d-dimensional fractional advection-dispersion equation. We also study the connection with multidimensional L\\'evy processes.

  7. Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution

    Science.gov (United States)

    Stevenson, Amadeus PZ; Blanco Bea, Duani; Civit, Sergi; Antoranz Contera, Sonia; Iglesias Cerveto, Alberto; Trigueros, Sonia

    2012-02-01

    Silver nanoparticles are extensively used due to their chemical and physical properties and promising applications in areas such as medicine and electronics. Controlled synthesis of silver nanoparticles remains a major challenge due to the difficulty in producing long-term stable particles of the same size and shape in aqueous solution. To address this problem, we examine three strategies to stabilise aqueous solutions of 15 nm citrate-reduced silver nanoparticles using organic polymeric capping, bimetallic core-shell and bimetallic alloying. Our results show that these strategies drastically improve nanoparticle stability by distinct mechanisms. Additionally, we report a new role of polymer functionalisation in preventing further uncontrolled nanoparticle growth. For bimetallic nanoparticles, we attribute the presence of a higher valence metal on the surface of the nanoparticle as one of the key factors for improving their long-term stability. Stable silver-based nanoparticles, free of organic solvents, will have great potential for accelerating further environmental and nanotoxicity studies. PACS: 81.07.-b; 81.16.Be; 82.70.Dd.

  8. Sweet Work with Fractions

    Science.gov (United States)

    Vinogradova, Natalya; Blaine, Larry

    2013-01-01

    Almost everyone loves chocolate. However, the same cannot be said about fractions, which are loved by markedly fewer. Middle school students tend to view them with wary respect, but little affection. The authors attempt to sweeten the subject by describing a type of game involving division of chocolate bars. The activity they describe provides a…

  9. Fermion Number Fractionization

    Indian Academy of Sciences (India)

    Srimath

    1 . In tro d u ctio n. T he N obel P rize in C hem istry for the year 2000 w as aw arded to A lan J H ... soliton, the ground state of the ferm ion-soliton system can have ..... probability density,in a heuristic w ay that a fractional ferm ion num ber m ay ...

  10. Momentum fractionation on superstrata

    International Nuclear Information System (INIS)

    Bena, Iosif; Martinec, Emil; Turton, David; Warner, Nicholas P.

    2016-01-01

    Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in high-degree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifold singularities. Upon taking the AdS_3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Our construction establishes the very nontrivial fact that large classes of CFT states with momentum fractionation can be realized in the bulk as smooth horizonless supergravity solutions.

  11. Fractional Differential Equation

    Directory of Open Access Journals (Sweden)

    Moustafa El-Shahed

    2007-01-01

    where 2<α<3 is a real number and D0+α is the standard Riemann-Liouville fractional derivative. Our analysis relies on Krasnoselskiis fixed point theorem of cone preserving operators. An example is also given to illustrate the main results.

  12. Vapor liquid fraction determination

    International Nuclear Information System (INIS)

    1980-01-01

    This invention describes a method of measuring liquid and vapor fractions in a non-homogeneous fluid flowing through an elongate conduit, such as may be required with boiling water, non-boiling turbulent flows, fluidized bed experiments, water-gas mixing analysis, and nuclear plant cooling. (UK)

  13. Brewing with fractionated barley

    NARCIS (Netherlands)

    Donkelaar, van L.H.G.

    2016-01-01

    Brewing with fractionated barley

    Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental

  14. Fractionation and rectification apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Sauerwald, A

    1932-05-25

    Fractionation and rectifying apparatus with a distillation vessel and a stirring tube, drainage tubes leading from its coils to a central collecting tube, the drainage tubes being somewhat parallel and attached to the outer half of the stirring tube and partly on the inner half of the central collecting tube, whereby distillation and rectification can be effected in a single apparatus.

  15. Fractional charge search

    International Nuclear Information System (INIS)

    Innes, W.; Klein, S.; Perl, M.; Price, J.C.

    1982-06-01

    A device to search for fractional charge in matter is described. The sample is coupled to a low-noise amplifier by a periodically varying capacitor and the resulting signal is synchronously detected. The varying capacitor is constructed as a rapidly spinning wheel. Samples of any material in volumes of up to 0.05 ml may be searched in less than an hour

  16. Generation and manipulation of monodispersed ferrofluid emulsions: the effect of a uniform magnetic field in flow-focusing and T-junction configurations.

    Science.gov (United States)

    Tan, Say Hwa; Nguyen, Nam-Trung

    2011-09-01

    This paper demonstrates the use of magnetically controlled microfluidic devices to produce monodispersed ferrofluid emulsions. By applying a uniform magnetic field on flow-focusing and T-junction configurations, the size of the ferrofluid emulsions can be actively controlled. The influences of the flow rates, the orientation, and the polarity of the magnetic field on the size of ferrofluid emulsions produced in both flow-focusing and T-junction configurations are compared and discussed.

  17. Human proton coupled folic acid transporter is a monodisperse oligomer in the lauryl maltose neopentyl glycol solubilized state.

    Science.gov (United States)

    Aduri, Nanda G; Ernst, Heidi A; Prabhala, Bala K; Bhatt, Shweta; Boesen, Thomas; Gajhede, Michael; Mirza, Osman

    2018-01-08

    The human proton coupled folic acid transporter PCFT is the major import route for dietary folates. Mutations in the gene encoding PCFT cause hereditary folic acid malabsorption, which manifests itself by compromised folate absorption from the intestine and also in impaired folate transport into the central nervous system. Since its recent discovery, PCFT has been the subject of numerous biochemical studies aiming at understanding its structure and mechanism. One major focus has been its oligomeric state, with some reports supporting oligomers and others a monomer. Here, we report the overexpression and purification of recombinant PCFT. Following detergent screening, n-Dodecyl β-D-maltoside (DDM) and lauryl maltose neopentyl glycol (LMNG) were chosen for further work as they exhibited the most optimal solubilization. We found that purified detergent solubilized PCFT was able to bind folic acid, thus indicating a functionally active protein. Size exclusion chromatography showed that PCFT in DDM was polydisperse; the LMNG preparation was clearly monodisperse but with shorter retention time than the major DDM peak. To assess the oligomeric state negative stain electron microscopy was performed which showed a particle with the size of a PCFT dimer. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Preparing Monodisperse Macromolecular Samples for Successful Biological Small-Angle X-ray and Neutron Scattering Experiments

    Science.gov (United States)

    Jeffries, Cy M.; Graewert, Melissa A.; Blanchet, Clément E.; Langley, David B.; Whitten, Andrew E.; Svergun, Dmitri I

    2017-01-01

    Small-angle X-ray and neutron scattering (SAXS and SANS) are techniques used to extract structural parameters and determine the overall structures and shapes of biological macromolecules, complexes and assemblies in solution. The scattering intensities measured from a sample contain contributions from all atoms within the illuminated sample volume including the solvent and buffer components as well as the macromolecules of interest. In order to obtain structural information, it is essential to prepare an exactly matched solvent blank so that background scattering contributions can be accurately subtracted from the sample scattering to obtain the net scattering from the macromolecules in the sample. In addition, sample heterogeneity caused by contaminants, aggregates, mismatched solvents, radiation damage or other factors can severely influence and complicate data analysis so it is essential that the samples are pure and monodisperse for the duration of the experiment. This Protocol outlines the basic physics of SAXS and SANS and reveals how the underlying conceptual principles of the techniques ultimately ‘translate’ into practical laboratory guidance for the production of samples of sufficiently high quality for scattering experiments. The procedure describes how to prepare and characterize protein and nucleic acid samples for both SAXS and SANS using gel electrophoresis, size exclusion chromatography and light scattering. Also included are procedures specific to X-rays (in-line size exclusion chromatography SAXS) and neutrons, specifically preparing samples for contrast matching/variation experiments and deuterium labeling of proteins. PMID:27711050

  19. Insights into magnetic interactions in a monodisperse Gd{sub 12}Fe{sub 14} metal cluster

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Xiu-Ying; Zhang, Hui; Liu, Pengxin; Du, Ming-Hao; Han, Ying-Zi; Wei, Rong-Jia; Kong, Xiang-Jian; Long, La-Sheng; Zheng, Lan-Sun [Collaborative Innovation Center of Chemistry for Energy Materials, State Key Lab. of Physical Chemistry of Solid Surface and Dept. of Chemistry, College of Chemistry and Chemical Engineering, Xiamen Univ. (China); Wang, Zhenxing; Ouyang, Zhong-Wen [Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan (China); Zhuang, Gui-Lin [College of Chemcal Engineering, Zhejiang University of Technology, Hangzhou (China)

    2017-09-11

    The largest Ln-Fe metal cluster [Gd{sub 12}Fe{sub 14}(μ{sub 3}-OH){sub 12}(μ{sub 4}-OH){sub 6}(μ{sub 4}-O){sub 12}(TEOA){sub 6}(CH{sub 3}COO){sub 16}(H{sub 2} O){sub 8}].(CH{sub 3}COO){sub 2}(CH{sub 3}CN){sub 2}.(H{sub 2}O){sub 20} (1) and the core-shell monodisperse metal cluster of 1 a rate at SiO{sub 2} (1 a=[Gd{sub 12}Fe{sub 14}(μ{sub 3}-OH){sub 12}(μ{sub 4}-OH){sub 6}(μ{sub 4}-O){sub 12}(TEOA){sub 6}(CH{sub 3}COO){sub 16} (H{sub 2}O){sub 8}]{sup 2+}) were prepared. Experimental and theoretical studies on the magnetic properties of 1 and 1 a rate at SiO{sub 2} reveal that encapsulation of one cluster into one silica nanosphere not only effectively decreases intermolecular magnetic interactions but also significantly increases the zero-field splitting effect of the outer layer Fe{sup 3+} ions. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Facile synthesis of monodisperse superparamagnetic Fe{sub 3}O{sub 4}/PMMA composite nanospheres with high magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Lan Fang; Liu Kexia; Jiang Wen; Zeng Xiaobo; Wu Yao; Gu Zhongwei, E-mail: Yaowu_amanda@126.com, E-mail: zwgu@scu.edu.cn [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

    2011-06-03

    Monodisperse superparamagnetic Fe{sub 3}O{sub 4}/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe{sub 3}O{sub 4}/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe{sub 3}O{sub 4} nanoparticles. VSM and TGA showed that the Fe{sub 3}O{sub 4}/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g{sup -1} (total mass), which was only decreased by 17% compared with the initial bare Fe{sub 3}O{sub 4} nanoparticles.

  1. Cluster synthesis of monodisperse rutile-TiO2 nanoparticles and dielectric TiO2-vinylidene fluoride oligomer nanocomposites

    International Nuclear Information System (INIS)

    Balasubramanian, Balamurugan; Kraemer, Kristin L; Valloppilly, Shah R; Ducharme, Stephen; Sellmyer, David J

    2011-01-01

    The embedding of oxide nanoparticles in polymer matrices produces a greatly enhanced dielectric response by combining the high dielectric strength and low loss of suitable host polymers with the high electric polarizability of nanoparticles. The fabrication of oxide-polymer nanocomposites with well-controlled distributions of nanoparticles is, however, challenging due to the thermodynamic and kinetic barriers between the polymer matrix and nanoparticle fillers. In the present study, monodisperse TiO 2 nanoparticles having an average particle size of 14.4 nm and predominant rutile phase were produced using a cluster-deposition technique without high-temperature thermal annealing and subsequently coated with uniform vinylidene fluoride oligomer (VDFO) molecules using a thermal evaporation source, prior to deposition as TiO 2 -VDFO nanocomposite films on suitable substrates. The molecular coatings on TiO 2 nanoparticles serve two purposes, namely to prevent the TiO 2 nanoparticles from contacting each other and to couple the nanoparticle polarization to the matrix. Parallel-plate capacitors made of TiO 2 -VDFO nanocomposite film as the dielectric exhibit minimum dielectric dispersion and low dielectric loss. Dielectric measurements also show an enhanced effective dielectric constant in TiO 2 -VDFO nanocomposites as compared to that of pure VDFO. This study demonstrates for the first time a unique electroactive particle coating in the form of a ferroelectric VDFO that has high-temperature stability as compared to conventionally used polymers for fabricating dielectric oxide-polymer nanocomposites.

  2. A posteriori determination of the useful data range for small-angle scattering experiments on dilute monodisperse systems.

    Science.gov (United States)

    Konarev, Petr V; Svergun, Dmitri I

    2015-05-01

    Small-angle X-ray and neutron scattering (SAXS and SANS) experiments on solutions provide rapidly decaying scattering curves, often with a poor signal-to-noise ratio, especially at higher angles. On modern instruments, the noise is partially compensated for by oversampling, thanks to the fact that the angular increment in the data is small compared with that needed to describe adequately the local behaviour and features of the scattering curve. Given a (noisy) experimental data set, an important question arises as to which part of the data still contains useful information and should be taken into account for the interpretation and model building. Here, it is demonstrated that, for monodisperse systems, the useful experimental data range is defined by the number of meaningful Shannon channels that can be determined from the data set. An algorithm to determine this number and thus the data range is developed, and it is tested on a number of simulated data sets with various noise levels and with different degrees of oversampling, corresponding to typical SAXS/SANS experiments. The method is implemented in a computer program and examples of its application to analyse the experimental data recorded under various conditions are presented. The program can be employed to discard experimental data containing no useful information in automated pipelines, in modelling procedures, and for data deposition or publication. The software is freely accessible to academic users.

  3. Preparation and unique electrical behaviors of monodispersed hybrid nanorattles of metal nanocores with hairy electroactive polymer shells.

    Science.gov (United States)

    Cai, Tao; Zhang, Bin; Chen, Yu; Wang, Cheng; Zhu, Chun Xiang; Neoh, Koon-Gee; Kang, En-Tang

    2014-03-03

    A versatile template-assisted strategy for the preparation of monodispersed rattle-type hybrid nanospheres, encapsulating a movable Au nanocore in the hollow cavity of a hairy electroactive polymer shell (Au@air@PTEMA-g-P3HT hybrid nanorattles; PTEMA: poly(2-(thiophen-3-yl)ethyl methacrylate; P3HT: poly(3-hexylthiophene), was reported. The Au@silica core-shell nanoparticles, prepared by the modified Stöber sol-gel process on Au nanoparticle seeds, were used as templates for the synthesis of Au@silica@PTEMA core-double shell nanospheres. Subsequent oxidative graft polymerization of 3-hexylthiophene from the exterior surface of the Au@silica@PTEMA core-double shell nanospheres allowed the tailoring of surface functionality with electroactive P3HT brushes (Au@silica@PTEMA-g-P3HT nanospheres). The Au@air@ PTEMA-g-P3HT hybrid nanorattles were obtained after etching of the silica interlayer by HF. The as-prepared nanorattles were dispersed into an electrically insulating polystyrene matrix and for the first time used to fabricate nonvolatile memory devices. As a result, unique electrical behaviors, including insulator behavior, write-once-read-many-times and rewritable memory effects, and conductor behavior as well, were observed in the Al/Au@air@PTEMA-g-P3HT+PS/ITO (ITO: indium-tin oxide) sandwich thin-film devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Evaluation of {sup 211}At-labelled monodisperse polymer particles in vivo: comparison of different specific activities

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, R.H.; Hoff, Per; Alstad, Jorolf [Oslo Univ., Chemistry Dept., Oslo (Norway); Varaas, Tone; De Vos, L.N.; Nustad, Kjell [Norwegian Radium Hospital, Central Lab., Oslo (Norway); Vergote, I.B. [Norwegian Radium Hospital, Gynecologic Oncology Dept., Oslo (Norway)

    1996-09-01

    The {alpha}-particle emitter {sup 211}At was covalently coupled to 1.8 {mu}m aminated monodisperse polymer particles (MDPP) and used to irradiate the intraperitoneal cavity in mice with disseminated tumour cells. Specific activity has previously been shown to influence the therapeutic efficacy of {alpha}-particle emitting compounds and the therapeutic efficacy of {sup 211}At-MDPP with various specific activity was therefore investigated. Groups of mice (10 animals per group) were treated with intraperitoneal injections of 100 kBq of {sup 211}At-MDPP with specific activities of 0.19, 0.55, 1.7, 5.0, 15, and 45 MBq/mg. A significantly prolonged survival was observed in the treated groups compared to the control group (from 19 to 26 days vs. 12 days, median). The difference in survival between the {sup 211}At-MDPP treated groups was not significant, but some animals with short survival were observed in the groups that had received the 0.19, 15 and 45 MBq/mg preparations. K13 monoclonal antibody values, which are an indicator of tumour growth, were high in some animals in the 15 and 45 MBq/mg groups (day 7 values). (author).

  5. Fabrication and characterisation of ligand-functionalised ultrapure monodispersed metal nanoparticle nanoassemblies employing advanced gas deposition technique

    Science.gov (United States)

    Geremariam Welearegay, Tesfalem; Cindemir, Umut; Österlund, Lars; Ionescu, Radu

    2018-02-01

    Here, we report for the first time the fabrication of ligand-functionalised ultrapure monodispersed metal nanoparticles (Au, Cu, and Pt) from their pure metal precursors using the advanced gas deposition technique. The experimental conditions during nanoparticle formation were adjusted in order to obtain ultrafine isolated nanoparticles on different substrates. The morphology and surface analysis of the as-deposited metal nanoparticles were investigated using scanning electron microscopy, x-ray diffraction and Fourier transform infra-red spectroscopy, which demonstrated the formation of highly ordered pure crystalline nanoparticles with a relatively uniform size distribution of ∼10 nm (Au), ∼4 nm (Cu) and ∼3 nm (Pt), respectively. A broad range of organic ligands containing thiol or amine functional groups were attached to the nanoparticles to form continuous networks of nanoparticle-ligand nanoassemblies, which were characterised by scanning electron microscopy and x-ray photoelectron spectroscopy. The electrical resistance of the functional nanoassemblies deposited in the gap spacing of two microfabricated parallel Au electrodes patterned on silicon substrates ranged between tens of kΩ and tens of MΩ, which is suitable for use in many applications including (bio)chemical sensors, surface-enhanced Raman spectroscopy and molecular electronic rectifiers.

  6. Enhanced visible light photocatalytic properties of Fe-doped TiO2 nanorod clusters and monodispersed nanoparticles

    International Nuclear Information System (INIS)

    Liu, Y.; Wei, J.H.; Xiong, R.; Pan, C.X.; Shi, J.

    2011-01-01

    In order to get photocatalysts with desired morphologies and enhanced visible light responses, the Fe-doped TiO 2 nanorod clusters and monodispersed nanoparticles were prepared by modified hydrothermal and solvothermal method, respectively. The microstructures and morphologies of TiO 2 crystals can be controlled by restraining the hydrolytic reaction rates. The Fe-doped photocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectroscopy (UV-vis), N 2 adsorption-desorption measurement (BET), and photoluminescence spectroscopy (PL). The refinements of the microstructures and morphologies result in the enhancement of the specific surface areas. The Fe 3+ -dopants in TiO 2 lattices not only lead to the significantly extending of the optical responses from UV to visible region but also diminish the recombination rates of the electrons and holes. The photocatalytic activities were evaluated by photocatalytic decomposition of formaldehyde in air under visible light illumination. Compared with P25 (TiO 2 ) and N-doped TiO 2 nanoparticles, the Fe-doped photocatalysts show high photocatalytic activities under visible light.

  7. Macrocyclic receptors immobilized to monodisperse porous polymer particles by chemical grafting and physical impregnation for strontium capture: a comparative study.

    Science.gov (United States)

    Song, Yang; Du, Yi; Lv, Dachao; Ye, Gang; Wang, Jianchen

    2014-06-15

    Separation of strontium is of great significance for radioactive waste treatment and environmental remediation after nuclear accidents. In this work, a novel class of adsorbent (Crown-g-MPPPs) was synthesized by chemical grafting a macrocyclic ether receptor to monodisperse porous polymer particles (MPPPs) for strontium adsorption. Meanwhile, a counterpart material (Crown@MPPPs) with the receptor molecules immobilized to the MPPPs substrate by physical impregnation was prepared. To investigate how the immobilization manner and distribution of the receptors influence the adsorption ability, a comparative study on the adsorption behaviour of the two materials towards Sr(II) in HNO3 media was accomplished. Due to the shorter diffusion path and covalently-bonded structure, Crown-g-MPPPs showed faster adsorption kinetics and better stability for cycle use. While Crown@MPPPs had the advantages of facile synthesis and higher adsorption capacity, owing to the absence of conformational constraint to form complexation with Sr(II). Kinetic functions (Lagergren pseudo-first-order/pseudo-second-order functions) and adsorption isotherm models (Langmuir/Freundlich models) were used to fit the experimental data and examine the adsorption mechanism. On this basis, a chromatographic process was proposed by using Crown@MPPPs for an effective separation of Sr(II) (91%) in simulated high level liquid waste (HLLW). Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Monodisperse Pt atoms anchored on N-doped graphene as efficient catalysts for CO oxidation: A first-principles investigation

    KAUST Repository

    Liu, Xin; Sui, Yanhui; Duan, Ting; Meng, Changgong; Han, Yu

    2015-01-01

    We performed first-principles based calculations to investigate the electronic structure and the potential catalytic performance of Pt atoms monodispersed on N-doped graphene in CO oxidation. We showed that N-doping can introduce localized defect states in the vicinity of the Fermi level of graphene which will effectively stabilize the deposited Pt atoms. The binding energy of a single Pt atom onto a stable cluster of 3 pyridinic N (PtN3) is up to -4.47 eV, making the diffusion and aggregation of anchored Pt atoms difficult. Both the reaction thermodynamics and kinetics suggest that CO oxidation over PtN3 would proceed through the Langmuir-Hinshelwood mechanism. The reaction barriers for the formation and dissociation of the peroxide-like intermediate are determined to be as low as 0.01 and 0.08 eV, respectively, while that for the regeneration is only 0.15 eV, proving the potential high catalytic performance of PtN3 in CO oxidation, especially at low temperatures. The Pt-d states that are up-shifted by the Pt-N interaction account for the enhanced activation of O2 and the efficient formation and dissociation of the peroxide-like intermediate.

  9. Droplet size effects on NO/x/ formation in a one-dimensional monodisperse spray combustion system

    Science.gov (United States)

    Sarv, H.; Nizami, A. A.; Cernansky, N. P.

    1982-01-01

    A one-dimensional monodisperse aerosol spray combustion facility is described and experimental results of post flame NO/NO(x) emissions are presented. Four different hydrocarbon fuels were studied: isopropanol, methanol, n-heptane, and n-octane. The results indicate an optimum droplet size in the range of 48-58 microns for minimizing NO/NO(x) production for all of the test fuels. This NO(x) behavior is associated with droplet interactions and the transition from diffusive type of spray burning to that of a prevaporized and premixed case. Decreasing the droplet size results in a trend of increasing droplet interactions, which suppresses temperatures and reduces NO(x). This trend continues until prevaporization effects begin to dominate and the system tends towards the premixed limit. The occurrence of the minimum NO(x) point at different droplet diameters for the different fuels appears to be governed by the extent of prevaporization of the fuel in the spray, and is consistent with theoretical calculations based on each fuel's physical properties.

  10. Preparation and characterization of monodisperse microcapsules with alginate and bentonite via external gelation technique encapsulating Pseudomonas putida Rs-198.

    Science.gov (United States)

    Li, Xuan; Wu, Zhansheng; He, Yanhui; Ye, Bang-Ce; Wang, Jun

    2017-10-01

    This paper evaluated the external gelation technique for preparing microcapsules. The microcapsules were consisted of Pseudomonas putida Rs-198 (Rs-198) core and sodium alginate (NaAlg)-bentonite (Bent) shell. Different emulsification rotation speeds and core/shell ratios were used to prepare the microcapsules of each formulation. The near-spherical microcapsules were monodisperse with a mean diameter of 25-100 μm and wrinkled surfaces. Fourier transform infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA) revealed the physical mixture of the wall material and the superior thermal stability of the microcapsules. Percentage yield, water content, and encapsulation efficiency were evaluated and correlated with the changes in emulsification rotation speed and core/shell ratio. In vitro release experiments demonstrated that 60% of the bacteria were released from the NaAlg-Bent microcapsules within three days. Considerably better survival was observed for encapsulated cells compared to free cells, especially in pH 4.0 and 10.0. In summary, the desired properties of microcapsules can be obtained by external gelation technique and the microcapsules on the bacteria had a good protective effect.

  11. Self-Templated Stepwise Synthesis of Monodispersed Nanoscale Metalated Covalent Organic Polymers for In Vivo Bioimaging and Photothermal Therapy.

    Science.gov (United States)

    Shi, Yanshu; Deng, Xiaoran; Bao, Shouxin; Liu, Bei; Liu, Bin; Ma, Ping'an; Cheng, Ziyong; Pang, Maolin; Lin, Jun

    2017-09-05

    Size- and shape-controlled growth of nanoscale microporous organic polymers (MOPs) is a big challenge scientists are confronted with; meanwhile, rendering these materials for in vivo biomedical applications is still scarce. In this study, a monodispersed nanometalated covalent organic polymer (MCOP, M=Fe, Gd) with sizes around 120 nm was prepared by a self-templated two-step solution-phase synthesis method. The metal ions (Fe 3+ , Gd 3+ ) played important roles in generating a small particle size and in the functionalization of the products during the reaction with p-phenylenediamine (Pa). The resultant Fe-Pa complex was used as a template for the subsequent formation of MCOP following the Schiff base reaction with 1,3,5-triformylphloroglucinol (Tp). A high tumor suppression efficiency for this Pa-based COP is reported for the first time. This study demonstrates the potential use of MCOP as a photothermal agent for photothermal therapy (PTT) and also provides an alternative route to fabricate nano-sized MCOPs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. -Dimensional Fractional Lagrange's Inversion Theorem

    Directory of Open Access Journals (Sweden)

    F. A. Abd El-Salam

    2013-01-01

    Full Text Available Using Riemann-Liouville fractional differential operator, a fractional extension of the Lagrange inversion theorem and related formulas are developed. The required basic definitions, lemmas, and theorems in the fractional calculus are presented. A fractional form of Lagrange's expansion for one implicitly defined independent variable is obtained. Then, a fractional version of Lagrange's expansion in more than one unknown function is generalized. For extending the treatment in higher dimensions, some relevant vectors and tensors definitions and notations are presented. A fractional Taylor expansion of a function of -dimensional polyadics is derived. A fractional -dimensional Lagrange inversion theorem is proved.

  13. Gauge invariant fractional electromagnetic fields

    International Nuclear Information System (INIS)

    Lazo, Matheus Jatkoske

    2011-01-01

    Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators. -- Highlights: → We propose a fractional Lagrangian formulation for fractional Maxwell's fields. → We obtain gauge invariant fractional electromagnetic fields. → Our generalized fractional Maxwell's field is spatially symmetrical. → We discuss the non-causality of the theory.

  14. Gauge invariant fractional electromagnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Lazo, Matheus Jatkoske, E-mail: matheuslazo@furg.br [Instituto de Matematica, Estatistica e Fisica - FURG, Rio Grande, RS (Brazil)

    2011-09-26

    Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators. -- Highlights: → We propose a fractional Lagrangian formulation for fractional Maxwell's fields. → We obtain gauge invariant fractional electromagnetic fields. → Our generalized fractional Maxwell's field is spatially symmetrical. → We discuss the non-causality of the theory.

  15. On matrix fractional differential equations

    Directory of Open Access Journals (Sweden)

    Adem Kılıçman

    2017-01-01

    Full Text Available The aim of this article is to study the matrix fractional differential equations and to find the exact solution for system of matrix fractional differential equations in terms of Riemann–Liouville using Laplace transform method and convolution product to the Riemann–Liouville fractional of matrices. Also, we show the theorem of non-homogeneous matrix fractional partial differential equation with some illustrative examples to demonstrate the effectiveness of the new methodology. The main objective of this article is to discuss the Laplace transform method based on operational matrices of fractional derivatives for solving several kinds of linear fractional differential equations. Moreover, we present the operational matrices of fractional derivatives with Laplace transform in many applications of various engineering systems as control system. We present the analytical technique for solving fractional-order, multi-term fractional differential equation. In other words, we propose an efficient algorithm for solving fractional matrix equation.

  16. Fractional, biodegradable and spectral characteristics of extracted and fractionated sludge extracellular polymeric substances.

    Science.gov (United States)

    Wei, Liang-Liang; Wang, Kun; Zhao, Qing-Liang; Jiang, Jun-Qiu; Kong, Xiang-Juan; Lee, Duu-Jong

    2012-09-15

    Correlation between fractional, biodegradable and spectral characteristics of sludge extracellular polymeric substances (EPS) by different protocols has not been well established. This work extracted sludge EPS using alkaline extractants (NH₄OH and formaldehyde + NaOH) and physical protocols (ultrasonication, heating at 80 °C or cation exchange resin (CER)) and then fractionated the extracts using XAD-8/XAD-4 resins. The alkaline extractants yielded more sludge EPS than the physical protocols. However, the physical protocols extracted principally the hydrophilic components which were readily biodegradable by microorganisms. The alkaline extractants dissolved additional humic-like substances from sludge solids which were refractory in nature. Different extraction protocols preferably extracted EPS with distinct fractional, biodegradable and spectral characteristics which could be applied in specific usages. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. The Local Fractional Bootstrap

    DEFF Research Database (Denmark)

    Bennedsen, Mikkel; Hounyo, Ulrich; Lunde, Asger

    We introduce a bootstrap procedure for high-frequency statistics of Brownian semistationary processes. More specifically, we focus on a hypothesis test on the roughness of sample paths of Brownian semistationary processes, which uses an estimator based on a ratio of realized power variations. Our...... new resampling method, the local fractional bootstrap, relies on simulating an auxiliary fractional Brownian motion that mimics the fine properties of high frequency differences of the Brownian semistationary process under the null hypothesis. We prove the first order validity of the bootstrap method...... and in simulations we observe that the bootstrap-based hypothesis test provides considerable finite-sample improvements over an existing test that is based on a central limit theorem. This is important when studying the roughness properties of time series data; we illustrate this by applying the bootstrap method...

  18. Toxicity of inhaled 239PuO2 in Beagle dogs. A. Monodisperse 0.75 μm AD particles. B. Monodisperse 1.5 μm AD particles. C. Monodisperse 3.0 μm AD particles. II

    International Nuclear Information System (INIS)

    Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; McClellan, R.O.; Mauderly, J.L.; Mewhinney, J.A.; Pickrell, J.A.; Boecker, B.B.

    1978-01-01

    Studies on the metabolism, dosimetry and biological effects of inhaled particles of 239 PuO 2 have been initiated in Beagle dogs. To obtain information on the relative importance of homogeneity of radiation doses to the lung, dogs have been exposed to particles of monodisperse aerosols (sigma/sub g/ 239 PuO 2 ; 40 dogs to the 0.75 μm AD particles, 72 dogs to the 1.5 μm AD particles and 60 dogs to the 3.0 μm AD particles. The exposures have resulted in graded ILB's, which range from 0.0002 to 2.6 μCi/kg body weight. Twenty-nine dogs were exposed to the aerosol diluent and serve as controls. Five dogs have died 336 to 561 days after exposure in the 1.5 μm AD study. Four dogs have died 116 to 589 days after exposure in the 3.0 μm AD study. These dogs had radiation pneumonitis and pulmonary fibrosis at death. The remaining dogs have survived up to 634 days after exposure. It is anticipated that the other dogs planned for these studies will be exposed over the next 12 months

  19. Toxicity of inhaled 239PuO2 in Beagle dogs. A. Monodisperse 0.75 μm AMAD particles. B. Monodisperse 1.5 μm AMAD particles. C. Monodisperse 3.0 μm AMAD particles. V

    International Nuclear Information System (INIS)

    Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; Boecker, B.B.; McClellan, R.O.; Mauderly, J.L.; Pickrell, J.A.

    1982-01-01

    Studies on the metabolism, dosimetry and biological effects of inhaled particles of 239 PuO 2 in Beagle dogs are in progress. To obtain information on the relative importance of homogeneity versus nonhomogeneity of radiation doses to the lung, dogs have been exposed to monodisperse aerosols of 239 PuO 2 of 0.75, 1.5 or 3.0 μm activity median aerodynamic diameter (AMAD). The exposures have resulted in graded initial lung burdens ranging from 0.0002 to 2.6 μCi 239 Pu per kilogram body weight. Other dogs were exposed to the aerosol diluent to serve as controls. Ten dogs have died in the study with 0.75 μm AMAD particles, 40 dogs have died in the study with 1.5 μm AMAD particles and 35 dogs have died in the study with 3.0 μm AMAD particles of 239 PuO 2 . Dogs have died with radiation pneumonitis and pulmonary fibrosis and carcinomas of the lung. The remaining dogs have survived up to 2100 days after inhalation exposure and are being observed for the remainder of their life span

  20. Toxicity of inhaled 239PuO2 in Beagle dogs: A. Monodisperse 0.75-μm AMAD particles. B. Monodisperse 1.5-μm AMAD particles. C. Monodisperse 3.0--μm AMAD particles. XI

    International Nuclear Information System (INIS)

    Muggenburg, B.A.; Guilmette, R.A.; Hahn, F.F.; Boecker, B.B.; McClellan, R.O.

    1988-01-01

    Beagle dogs were exposed to monodisperse aerosols of 239 PuO 2 of 0.75, 1.5, or 30 μm activity median aerodynamic diameter (AMAD) to obtain information on the relative importance of homogeneity of alpha irradiation doses to the lung in producing biological effects. The dogs' initial pulmonary burdens (IPB) ranged from 0.0002-2.0 μCi (0.0074 to 74 kBq) 239 Pu/kg of body mass. Thirty-six dogs were exposed to the aerosol diluent as controls. Forty-two of 48 dogs exposed to 0.75 μm AMAD particles have died; 67 of 96 have died in the study involving 1.5 μm AMAD particles; and 62 of 72 have died in the study involving the 3.0 μm AMAD particles. Seven of 36 control dogs have died. Most dogs exposed to 239 Pu that have failed to survive have died with radiation pneumonitis and fibrosis and/or lung cancer. Surviving dogs have lived up to 4300 days after exposure. The data obtained to date indicate that the degree of uniformity of dose to the lung does not significantly modify the risk of lung cancer. (author)

  1. Fractionalization and Entrepreneurial Activities

    OpenAIRE

    Awaworyi Churchill, Sefa

    2015-01-01

    The vast majority of the literature on ethnicity and entrepreneurship focuses on the construct of ethnic entrepreneurship. However, very little is known about how ethnic heterogeneity affects entrepreneurship. This study attempts to fill the gap, and thus examines the effect of ethnic heterogeneity on entrepreneurial activities in a cross-section of 90 countries. Using indices of ethnic and linguistic fractionalization, we show that ethnic heterogeneity negatively influences entrepreneurship....

  2. Fractional Number Operator and Associated Fractional Diffusion Equations

    Science.gov (United States)

    Rguigui, Hafedh

    2018-03-01

    In this paper, we study the fractional number operator as an analog of the finite-dimensional fractional Laplacian. An important relation with the Ornstein-Uhlenbeck process is given. Using a semigroup approach, the solution of the Cauchy problem associated to the fractional number operator is presented. By means of the Mittag-Leffler function and the Laplace transform, we give the solution of the Caputo time fractional diffusion equation and Riemann-Liouville time fractional diffusion equation in infinite dimensions associated to the fractional number operator.

  3. Minerals in soil select distinct bacterial communities in their microhabitats.

    Science.gov (United States)

    Carson, Jennifer K; Campbell, Louise; Rooney, Deirdre; Clipson, Nicholas; Gleeson, Deirdre B

    2009-03-01

    We tested the hypothesis that different minerals in soil select distinct bacterial communities in their microhabitats. Mica (M), basalt (B) and rock phosphate (RP) were incubated separately in soil planted with Trifolium subterraneum, Lolium rigidum or left unplanted. After 70 days, the mineral and soil fractions were separated by sieving. Automated ribosomal intergenic spacer analysis was used to determine whether the bacterial community structure was affected by the mineral, fraction and plant treatments. Principal coordinate plots showed clustering of bacterial communities from different fraction and mineral treatments, but not from different plant treatments. Permutational multivariate anova (permanova) showed that the microhabitats of M, B and RP selected bacterial communities different from each other in unplanted and L. rigidum, and in T. subterraneum, bacterial communities from M and B differed (Ppermanova also showed that each mineral fraction selected bacterial communities different from the surrounding soil fraction (P<0.05). This study shows that the structure of bacterial communities in soil is influenced by the mineral substrates in their microhabitat and that minerals in soil play a greater role in bacterial ecology than simply providing an inert matrix for bacterial growth. This study suggests that mineral heterogeneity in soil contributes to the spatial variation in bacterial communities.

  4. Gauge invariant fractional electromagnetic fields

    Science.gov (United States)

    Lazo, Matheus Jatkoske

    2011-09-01

    Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators.

  5. Presidential address: distinction or extinction.

    Science.gov (United States)

    Pressman, Barry D

    2008-10-01

    Despite its continuing scientific successes in imaging, radiology as a specialty is faced with a very difficult and competitive environment. Nonradiologists are more and more interested in vertically integrating imaging into their practices, while teleradiology and picture archiving and communication systems are resulting in the greater isolation of radiologists. Commoditization is a realistic and devastating threat to the survival and professionalism of the specialty. To remain viable as a specialty, radiologists must elevate their practice by subspecializing, becoming more involved with clinical care, and actively interacting with patients and referring clinicians. Distinction will prevent extinction.

  6. The Extended Fractional Subequation Method for Nonlinear Fractional Differential Equations

    OpenAIRE

    Zhao, Jianping; Tang, Bo; Kumar, Sunil; Hou, Yanren

    2012-01-01

    An extended fractional subequation method is proposed for solving fractional differential equations by introducing a new general ansätz and Bäcklund transformation of the fractional Riccati equation with known solutions. Being concise and straightforward, this method is applied to the space-time fractional coupled Burgers’ equations and coupled MKdV equations. As a result, many exact solutions are obtained. It is shown that the considered method provides a very effective, convenient, and powe...

  7. Functional Fractional Calculus

    CERN Document Server

    Das, Shantanu

    2011-01-01

    When a new extraordinary and outstanding theory is stated, it has to face criticism and skeptism, because it is beyond the usual concept. The fractional calculus though not new, was not discussed or developed for a long time, particularly for lack of its application to real life problems. It is extraordinary because it does not deal with 'ordinary' differential calculus. It is outstanding because it can now be applied to situations where existing theories fail to give satisfactory results. In this book not only mathematical abstractions are discussed in a lucid manner, with physical mathematic

  8. Fractional Reserve Banking

    OpenAIRE

    Andreasen, Niels; Bjerregaard, Mads; Lund, Jonas; Olsen, Ove Bitsch; Rasmussen, Andreas Dalgas

    2012-01-01

    Projektet er bygget op omkring kritisk realisme, som er det gennemgående videnskabelige fundament til undersøgelsen af hvilke strukturelle grunde der er til finansiel ustabilitet i Danmark. Projektet går i dybden med Fractional Reserve Banking og incitamentsstrukturen i banksystemet. Vi bevæger os både på det makro- og mikroøkonomiske niveau i analysen. På makro niveau bruger vi den østrigske skole om konjunktur teori (The Positive Theory of the Cycle). På mikro niveau arbejder vi med princip...

  9. Plasma fractionation issues.

    Science.gov (United States)

    Farrugia, Albert; Evers, Theo; Falcou, Pierre-Francois; Burnouf, Thierry; Amorim, Luiz; Thomas, Sylvia

    2009-04-01

    Procurement and processing of human plasma for fractionation of therapeutic proteins or biological medicines used in clinical practice is a multi-billion dollar international trade. Together the private sector and public sector (non-profit) provide large amounts of safe and effective therapeutic plasma proteins needed worldwide. The principal therapeutic proteins produced by the dichotomous industry include gamma globulins or immunoglobulins (including pathogen-specific hyperimmune globulins, such as hepatitis B immune globulins) albumin, factor VIII and Factor IX concentrates. Viral inactivation, principally by solvent detergent and other processes, has proven highly effective in preventing transmission of enveloped viruses, viz. HBV, HIV, and HCV.

  10. Determination of reactivity rates of silicate particle-size fractions

    Directory of Open Access Journals (Sweden)

    Angélica Cristina Fernandes Deus

    2014-04-01

    Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

  11. A fractional model with parallel fractional Maxwell elements for amorphous thermoplastics

    Science.gov (United States)

    Lei, Dong; Liang, Yingjie; Xiao, Rui

    2018-01-01

    We develop a fractional model to describe the thermomechanical behavior of amorphous thermoplastics. The fractional model is composed of two parallel fractional Maxwell elements. The first fractional Maxwell model is used to describe the glass transition, while the second component is aimed at describing the viscous flow. We further derive the analytical solutions for the stress relaxation modulus and complex modulus through Laplace transform. We then demonstrate the model is able to describe the master curves of the stress relaxation modulus, storage modulus and loss modulus, which all show two distinct transition regions. The obtained parameters show that the modulus of the two fractional Maxwell elements differs in 2-3 orders of magnitude, while the relaxation time differs in 7-9 orders of magnitude. Finally, we apply the model to describe the stress response of constant strain rate tests. The model, together with the parameters obtained from fitting the master curve of stress relaxation modulus, can accurately predict the temperature and strain rate dependent stress response.

  12. Advances in robust fractional control

    CERN Document Server

    Padula, Fabrizio

    2015-01-01

    This monograph presents design methodologies for (robust) fractional control systems. It shows the reader how to take advantage of the superior flexibility of fractional control systems compared with integer-order systems in achieving more challenging control requirements. There is a high degree of current interest in fractional systems and fractional control arising from both academia and industry and readers from both milieux are catered to in the text. Different design approaches having in common a trade-off between robustness and performance of the control system are considered explicitly. The text generalizes methodologies, techniques and theoretical results that have been successfully applied in classical (integer) control to the fractional case. The first part of Advances in Robust Fractional Control is the more industrially-oriented. It focuses on the design of fractional controllers for integer processes. In particular, it considers fractional-order proportional-integral-derivative controllers, becau...

  13. Search for fractional charge

    International Nuclear Information System (INIS)

    Turner, R.E.

    1984-01-01

    A search was made for fractional charges of the form Z plus two-thirds e, where Z is an integer. It was assumed that the charges exist in natural form bound with other fractional charges in neutral molecules. It was further assumed that these neutral molecules are present in air. Two concentration schemes were employed. One sample was derived from the waste gases from a xenon distillation plant. This assumes that high mass, low vapor pressure components of air are concentrated along with the xenon. The second sample involved ionizing air, allowing a brief recombination period, and then collecting residual ions on the surface of titanium discs. Both samples were analyzed at the University of Rochester in a system using a tandem Van de Graff to accelerate particles through an essentially electrostatic beam handling system. The detector system employed both a Time of Flight and an energy-sensitive gas ionization detector. In the most sensitive mode of analysis, a gas absorber was inserted in the beam path to block the intense background. The presence of an absorber limited the search to highly penetrating particles. Effectively, this limited the search to particles with low Z and masses greater than roughly fifty GeV. The final sensitivities attained were on the order of 1 x 10 -20 for the ionized air sample and 1 x 10 -21 for the gas sample. A discussion of the caveats that could reduce the actual level of sensitivity is included

  14. Fractional Reserve in Banking System

    OpenAIRE

    Valkonen, Maria

    2016-01-01

    This thesis is aimed to provide understanding of the role of the fractional reserve in the mod-ern banking system worldwide and particularly in Finland. The fractional reserve banking is used worldwide, but the benefits of this system are very disputable. On the one hand, experts say that the fractional reserve is a necessary instrument for the normal business and profit making. On the other hand, sceptics openly criticize the fractional reserve system and blame it for fiat money (money n...

  15. On matrix fractional differential equations

    OpenAIRE

    Adem Kılıçman; Wasan Ajeel Ahmood

    2017-01-01

    The aim of this article is to study the matrix fractional differential equations and to find the exact solution for system of matrix fractional differential equations in terms of Riemann–Liouville using Laplace transform method and convolution product to the Riemann–Liouville fractional of matrices. Also, we show the theorem of non-homogeneous matrix fractional partial differential equation with some illustrative examples to demonstrate the effectiveness of the new methodology. The main objec...

  16. Fractional Hopfield Neural Networks: Fractional Dynamic Associative Recurrent Neural Networks.

    Science.gov (United States)

    Pu, Yi-Fei; Yi, Zhang; Zhou, Ji-Liu

    2017-10-01

    This paper mainly discusses a novel conceptual framework: fractional Hopfield neural networks (FHNN). As is commonly known, fractional calculus has been incorporated into artificial neural networks, mainly because of its long-term memory and nonlocality. Some researchers have made interesting attempts at fractional neural networks and gained competitive advantages over integer-order neural networks. Therefore, it is naturally makes one ponder how to generalize the first-order Hopfield neural networks to the fractional-order ones, and how to implement FHNN by means of fractional calculus. We propose to introduce a novel mathematical method: fractional calculus to implement FHNN. First, we implement fractor in the form of an analog circuit. Second, we implement FHNN by utilizing fractor and the fractional steepest descent approach, construct its Lyapunov function, and further analyze its attractors. Third, we perform experiments to analyze the stability and convergence of FHNN, and further discuss its applications to the defense against chip cloning attacks for anticounterfeiting. The main contribution of our work is to propose FHNN in the form of an analog circuit by utilizing a fractor and the fractional steepest descent approach, construct its Lyapunov function, prove its Lyapunov stability, analyze its attractors, and apply FHNN to the defense against chip cloning attacks for anticounterfeiting. A significant advantage of FHNN is that its attractors essentially relate to the neuron's fractional order. FHNN possesses the fractional-order-stability and fractional-order-sensitivity characteristics.

  17. The random continued fraction transformation

    Science.gov (United States)

    Kalle, Charlene; Kempton, Tom; Verbitskiy, Evgeny

    2017-03-01

    We introduce a random dynamical system related to continued fraction expansions. It uses random combinations of the Gauss map and the Rényi (or backwards) continued fraction map. We explore the continued fraction expansions that this system produces, as well as the dynamical properties of the system.

  18. How Weird Are Weird Fractions?

    Science.gov (United States)

    Stuffelbeam, Ryan

    2013-01-01

    A positive rational is a weird fraction if its value is unchanged by an illegitimate, digit-based reduction. In this article, we prove that each weird fraction is uniquely weird and initiate a discussion of the prevalence of weird fractions.

  19. Do Children Understand Fraction Addition?

    Science.gov (United States)

    Braithwaite, David W.; Tian, Jing; Siegler, Robert S.

    2017-01-01

    Many children fail to master fraction arithmetic even after years of instruction. A recent theory of fraction arithmetic (Braithwaite, Pyke, & Siegler, in press) hypothesized that this poor learning of fraction arithmetic procedures reflects poor conceptual understanding of them. To test this hypothesis, we performed three experiments…

  20. On fractional Fourier transform moments

    NARCIS (Netherlands)

    Alieva, T.; Bastiaans, M.J.

    2000-01-01

    Based on the relation between the ambiguity function represented in a quasi-polar coordinate system and the fractional power spectra, the fractional Fourier transform moments are introduced. Important equalities for the global second-order fractional Fourier transform moments are derived and their

  1. Fractional dynamic calculus and fractional dynamic equations on time scales

    CERN Document Server

    Georgiev, Svetlin G

    2018-01-01

    Pedagogically organized, this monograph introduces fractional calculus and fractional dynamic equations on time scales in relation to mathematical physics applications and problems. Beginning with the definitions of forward and backward jump operators, the book builds from Stefan Hilger’s basic theories on time scales and examines recent developments within the field of fractional calculus and fractional equations. Useful tools are provided for solving differential and integral equations as well as various problems involving special functions of mathematical physics and their extensions and generalizations in one and more variables. Much discussion is devoted to Riemann-Liouville fractional dynamic equations and Caputo fractional dynamic equations.  Intended for use in the field and designed for students without an extensive mathematical background, this book is suitable for graduate courses and researchers looking for an introduction to fractional dynamic calculus and equations on time scales. .

  2. Controllable 5-sulfosalicylic acid assisted solvothermal synthesis of monodispersed superparamagnetic Fe{sub 3}O{sub 4} nanoclusters with tunable size

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wentao [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Tang, Bingtao, E-mail: tangbt@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Wu, Suli; Gao, Zhanming; Ju, Benzhi [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Teng, Xiaoxu [School of Chemistry and Chemical Engineering, Yangtze Normal University, Chongqing 408100 (China); Zhang, Shufen [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)

    2017-02-01

    Monodispersed Fe{sub 3}O{sub 4} nanoclusters were synthesized in a one-pot solvothermal route with 5-sulfosalicylic acid (SSA) as the functional ligand in a mixed-solvent system of diethylene glycol/ethylene glycol (DEG/EG). Nucleation and aggregation growth model was responsible for the formation of secondary structure of the clusters. In the process, the size of the clusters can be effectively controlled by varying the amounts of SSA and the volume ratio of DEG/EG. The nanoclusters exhibited superparamagnetic properties with high saturation magnetization value of about 68.7 emu g{sup −1} at room temperature. The water-soluble small-molecule SSA grafted on the surface of Fe{sub 3}O{sub 4} nanocrystals rendered the superparamagnetic clusters dispersible in water, which is crucial for potential applications in biomedical fields. - Graphical abstract: 5-sulfosalicylic acid assisted solvothermal synthesis of monodispersed superparamagnetic Fe{sub 3}O{sub 4} nanoclusters with tunable size by a mixed-solvent system of DEG/EG. - Highlights: • Monodispersed Fe{sub 3}O{sub 4} nanoclusters were synthesized in a one-pot 5-sulfosalicylic acid assisted solvothermal route. • The size of the clusters are tunable by varying the amounts of 5-sulfosalicylic acid and the volume ratio of DEG/EG. • The nanoclusters exhibited superparamagnetic properties with high saturation magnetization value. • The 5-sulfosalicylic acid grafted Fe{sub 3}O{sub 4} nanoclusters can be dispersed in water.

  3. Nonhomogeneous fractional Poisson processes

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaotian [School of Management, Tianjin University, Tianjin 300072 (China)]. E-mail: swa001@126.com; Zhang Shiying [School of Management, Tianjin University, Tianjin 300072 (China); Fan Shen [Computer and Information School, Zhejiang Wanli University, Ningbo 315100 (China)

    2007-01-15

    In this paper, we propose a class of non-Gaussian stationary increment processes, named nonhomogeneous fractional Poisson processes W{sub H}{sup (j)}(t), which permit the study of the effects of long-range dependance in a large number of fields including quantum physics and finance. The processes W{sub H}{sup (j)}(t) are self-similar in a wide sense, exhibit more fatter tail than Gaussian processes, and converge to the Gaussian processes in distribution in some cases. In addition, we also show that the intensity function {lambda}(t) strongly influences the existence of the highest finite moment of W{sub H}{sup (j)}(t) and the behaviour of the tail probability of W{sub H}{sup (j)}(t)

  4. Nonhomogeneous fractional Poisson processes

    International Nuclear Information System (INIS)

    Wang Xiaotian; Zhang Shiying; Fan Shen

    2007-01-01

    In this paper, we propose a class of non-Gaussian stationary increment processes, named nonhomogeneous fractional Poisson processes W H (j) (t), which permit the study of the effects of long-range dependance in a large number of fields including quantum physics and finance. The processes W H (j) (t) are self-similar in a wide sense, exhibit more fatter tail than Gaussian processes, and converge to the Gaussian processes in distribution in some cases. In addition, we also show that the intensity function λ(t) strongly influences the existence of the highest finite moment of W H (j) (t) and the behaviour of the tail probability of W H (j) (t)

  5. Membrane Assisted Enzyme Fractionation

    DEFF Research Database (Denmark)

    Yuan, Linfeng

    to the variation in size of the proteins and a reasonable separation factor can be observed only when the size difference is in the order of 10 or more. This is partly caused by concentration polarization and membrane fouling which hinders an effective separation of the proteins. Application of an electric field...... across the porous membrane has been demonstrated to be an effective way to reduce concentration polarization and membrane fouling. In addition, this technique can also be used to separate the proteins based on difference in charge, which to some extent overcome the limitations of size difference...... of proteins on the basis of their charge, degree of hydrophobicity, affinity or size. Adequate purity is often not achieved unless several purification steps are combined thereby increasing cost and reducing product yield. Conventional fractionation of proteins using ultrafiltration membranes is limited...

  6. Fraction Reduction in Membrane Systems

    Directory of Open Access Journals (Sweden)

    Ping Guo

    2014-01-01

    Full Text Available Fraction reduction is a basic computation for rational numbers. P system is a new computing model, while the current methods for fraction reductions are not available in these systems. In this paper, we propose a method of fraction reduction and discuss how to carry it out in cell-like P systems with the membrane structure and the rules with priority designed. During the application of fraction reduction rules, synchronization is guaranteed by arranging some special objects in these rules. Our work contributes to performing the rational computation in P systems since the rational operands can be given in the form of fraction.

  7. Thermochemical transformations of anthracite fractions

    Energy Technology Data Exchange (ETDEWEB)

    Belkina, T.V.; Privalov, V.E.; Stepanenko, atM.A.

    1979-08-01

    Research on the nature of thermochemical transformations of anthracite fractions and the possibility of increasing their activity and identifying conditions for their use in the electrode pitch process is described. From research done on different anthracite fractions processed at varying temperatures it was concluded that accumulations of condensates from heating anthracite fractions occur significantly slower in comparison with pitch. As a result the electrode pitch process is prolonged. Thermal treatment of an anthracite fraction causes the formation and accumulation of condensates and promotes thermochemical transformations. Lastly, the use of thermally treated anthracite fractions apparently intensifies the electrode pitch process and improves its quality. (16 refs.) (In Russian)

  8. Toward lattice fractional vector calculus

    Science.gov (United States)

    Tarasov, Vasily E.

    2014-09-01

    An analog of fractional vector calculus for physical lattice models is suggested. We use an approach based on the models of three-dimensional lattices with long-range inter-particle interactions. The lattice analogs of fractional partial derivatives are represented by kernels of lattice long-range interactions, where the Fourier series transformations of these kernels have a power-law form with respect to wave vector components. In the continuum limit, these lattice partial derivatives give derivatives of non-integer order with respect to coordinates. In the three-dimensional description of the non-local continuum, the fractional differential operators have the form of fractional partial derivatives of the Riesz type. As examples of the applications of the suggested lattice fractional vector calculus, we give lattice models with long-range interactions for the fractional Maxwell equations of non-local continuous media and for the fractional generalization of the Mindlin and Aifantis continuum models of gradient elasticity.

  9. Inductively coupled plasma mass spectrometry with a twin quadrupole instrument using laser ablation sample introduction and monodisperse dried microparticulate injection

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Lloyd A. [Iowa State Univ., Ames, IA (United States)

    1996-10-17

    The focus of this dissertation is the use of a twin quadrupole inductively coupled plasma mass spectrometer (ICP-MS) for the simultaneous detection of two m/z values. The twin quadrupole ICP-MS is used with laser ablation sample introduction in both the steady state (10 Hz) and single pulse modes. Steady state signals are highly correlated and the majority of flicker noise cancels when the ratio is calculated. Using a copper sample, the isotope ratio 63Cu+/65Cu+ is measured with a relative standard deviation (RSD) of 0.26%. Transient signals for single laser pulses are also obtained. Copper isotope ratio measurements for several laser pulses are measured with an RSD of 0.85%. Laser ablation (LA) is used with steel samples to assess the ability of the twin quadrupole ICP-MS to eliminate flicker noise of minor components of steel samples. Isotopic and internal standard ratios are measured in the first part of this work. The isotope ratio 52Cr+/53Cr+ (Cr present at 1.31 %) can be measured with an RSD of 0.06 % to 0.1 %. For internal standard elements, RSDs improve from 1.9 % in the Cr+ signal to 0.12% for the ratio of 51V+ to 52Cr+. In the second part of this work, one mass spectrometer is scanned while the second channel measures an individual m/z value. When the ratio of these two signals is calculated, the peak shapes in the mass spectrum are improved significantly. Pulses of analyte and matrix ions from individual drops are measured simultaneously using the twin quadrupole ICP-MS with monodisperse dried microparticulate injection (MDMI). At modest Pb concentrations (500 ppm), a shoulder on the leading edge of the Li+ signal becomes apparent. Space charge effects are consistent with the disturbances seen.

  10. Mechanisms of Complete Turbulence Suppression in Turbidity Currents Driven by Mono-Disperse and Bi-Disperse Suspensions of Sediment

    Directory of Open Access Journals (Sweden)

    Mrugesh S. Shringarpure

    2014-09-01

    appears to have a logarithmic dependence on Reτ (Cantero et al. 2012. DNS of turbidity currents driven by bi-disperse suspension of sediments is also carried out and compared with the results of mono-disperse suspensions.

  11. Automated preparation method for colloidal crystal arrays of monodisperse and binary colloid mixtures by contact printing with a pintool plotter.

    Science.gov (United States)

    Burkert, Klaus; Neumann, Thomas; Wang, Jianjun; Jonas, Ulrich; Knoll, Wolfgang; Ottleben, Holger

    2007-03-13

    Photonic crystals and photonic band gap materials with periodic variation of the dielectric constant in the submicrometer range exhibit unique optical properties such as opalescence, optical stop bands, and photonic band gaps. As such, they represent attractive materials for the active elements in sensor arrays. Colloidal crystals, which are 3D gratings leading to Bragg diffraction, are one potential precursor of such optical materials. They have gained particular interest in many technological areas as a result of their specific properties and ease of fabrication. Although basic techniques for the preparation of regular patterns of colloidal crystals on structured substrates by self-assembly of mesoscopic particles are known, the efficient fabrication of colloidal crystal arrays by simple contact printing has not yet been reported. In this article, we present a spotting technique used to produce a microarray comprising up to 9600 single addressable sensor fields of colloidal crystal structures with dimensions down to 100 mum on a microfabricated substrate in different formats. Both monodisperse colloidal crystals and binary colloidal crystal systems were prepared by contact printing of polystyrene particles in aqueous suspension. The array morphology was characterized by optical light microscopy and scanning electron microscopy, which revealed regularly ordered crystalline structures for both systems. In the case of binary crystals, the influence of the concentration ratio of the large and small particles in the printing suspension on the obtained crystal structure was investigated. The optical properties of the colloidal crystal arrays were characterized by reflection spectroscopy. To examine the stop bands of the colloidal crystal arrays in a high-throughput fashion, an optical setup based on a CCD camera was realized that allowed the simultaneous readout of all of the reflection spectra of several thousand sensor fields per array in parallel. In agreement with

  12. Misonidazole in fractionated radiotherapy: are many small fractions best

    International Nuclear Information System (INIS)

    Denekamp, J.; McNally, N.J.; Fowler, J.F.; Joiner, M.C.

    1980-01-01

    The largest sensitizing effect is always demonstrated with six fractions, each given with 2 g/m 2 of misonidazole. In the absence of reoxygenation a sensitizer enhancement ratio of 1.7 is predicted, but this falls to 1.1-1.2 if extensive reoxygenation occurs. Less sensitization is observed with 30 fractions, each with 0.4 g/m 2 of drug. However, for clinical use, the important question is which treatment kills the maximum number of tumour cells. Many of the simulations predict a marked disadvantage of reducing the fraction number for X rays alone. The circumstances in which this disadvantage is offset by the large Sensitizer enhancement ratio values with a six-fraction schedule are few. The model calculations suggest that many small fractions, each with a low drug dose, are safest unless the clinician has some prior knowledge that a change in fraction number is not disadvantageous. (author)

  13. Fractional statistics and fractional quantized Hall effect. Revision

    International Nuclear Information System (INIS)

    Tao, R.; Wu, Y.S.

    1984-01-01

    We suggest that the origin of the odd denominator rule observed in the fractional quantized Hall effect (FQHE) may lie in fractional statistics which governs quasiparticles in FQHE. A theorem concerning statistics of clusters of quasiparticles implies that fractional statistics does not allow coexistence of a large number of quasiparticles at fillings with an even denominator. Thus no Hall plateau can be formed at these fillings, regardless of the presence of an energy gap. 15 references

  14. Fractionation of Pb and Cu in the fine fraction (landfill.

    Science.gov (United States)

    Kaczala, Fabio; Orupõld, Kaja; Augustsson, Anna; Burlakovs, Juris; Hogland, Marika; Bhatnagar, Amit; Hogland, William

    2017-11-01

    The fractionation of metals in the fine fraction (landfill was carried out to evaluate the metal (Pb and Cu) contents and their potential towards not only mobility but also possibilities of recovery/extraction. The fractionation followed the BCR (Community Bureau of Reference) sequential extraction, and the exchangeable (F1), reducible (F2), oxidizable (F3) and residual fractions were determined. The results showed that Pb was highly associated with the reducible (F2) and oxidizable (F3) fractions, suggesting the potential mobility of this metal mainly when in contact with oxygen, despite the low association with the exchangeable fraction (F1). Cu has also shown the potential for mobility when in contact with oxygen, since high associations with the oxidizable fraction (F3) were observed. On the other hand, the mobility of metals in excavated waste can be seen as beneficial considering the circular economy and recovery of such valuables back into the economy. To conclude, not only the total concentration of metals but also a better understanding of fractionation and in which form metals are bound is very important to bring information on how to manage the fine fraction from excavated waste both in terms of environmental impacts and also recovery of such valuables in the economy.

  15. Fractional variational calculus in terms of Riesz fractional derivatives

    International Nuclear Information System (INIS)

    Agrawal, O P

    2007-01-01

    This paper presents extensions of traditional calculus of variations for systems containing Riesz fractional derivatives (RFDs). Specifically, we present generalized Euler-Lagrange equations and the transversality conditions for fractional variational problems (FVPs) defined in terms of RFDs. We consider two problems, a simple FVP and an FVP of Lagrange. Results of the first problem are extended to problems containing multiple fractional derivatives, functions and parameters, and to unspecified boundary conditions. For the second problem, we present Lagrange-type multiplier rules. For both problems, we develop the Euler-Lagrange-type necessary conditions which must be satisfied for the given functional to be extremum. Problems are considered to demonstrate applications of the formulations. Explicitly, we introduce fractional momenta, fractional Hamiltonian, fractional Hamilton equations of motion, fractional field theory and fractional optimal control. The formulations presented and the resulting equations are similar to the formulations for FVPs given in Agrawal (2002 J. Math. Anal. Appl. 272 368, 2006 J. Phys. A: Math. Gen. 39 10375) and to those that appear in the field of classical calculus of variations. These formulations are simple and can be extended to other problems in the field of fractional calculus of variations

  16. Modelling altered fractionation schedules

    International Nuclear Information System (INIS)

    Fowler, J.F.

    1993-01-01

    The author discusses the conflicting requirements of hyperfractionation and accelerated fractionation used in radiotherapy, and the development of computer modelling to predict how to obtain an optimum of tumour cell kill without exceeding normal-tissue tolerance. The present trend is to shorten hyperfractionated schedules from 6 or 7 weeks to give overall times of 4 or 5 weeks as in new schedules by Herskovic et al (1992) and Harari (1992). Very high doses are given, much higher than can be given when ultrashort schedules such as CHART (12 days) are used. Computer modelling has suggested that optimum overall times, to yield maximum cell kill in tumours ((α/β = 10 Gy) for a constant level of late complications (α/β = 3 Gy) would be X or X-1 weeks, where X is the doubling time of the tumour cells in days (Fowler 1990). For median doubling times of about 5 days, overall times of 4 or 5 weeks should be ideal. (U.K.)

  17. High lithium storage capacity achieved by regulating monodisperse C/In{sub 2}O{sub 3} nanosheet composite with double phases

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Lu; Pan, Xueqian; Chen, Shangqian; Song, Jialing; Liu, Cheng [Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Jiangsu, 224051 (China); Luo, Gaixia [Department of Physics, Yancheng Institute of Technology, Jiangsu, 224051 (China); Guan, Rongfeng [Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Jiangsu, 224051 (China); Zhang, Wenhui, E-mail: zwhuizi000@sina.com [Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Jiangsu, 224051 (China)

    2017-06-01

    Monodisperse C/In{sub 2}O{sub 3} nanosheet composites are prepared by D-fructose-assisted solvothermal approach. The effects of carbon content on the morphological evolution and electrochemical performance of C/In{sub 2}O{sub 3} nanosheet composites are investigated. The SEM and TEM are used to study the morphological evolution. C/In{sub 2}O{sub 3} nanosheet composite electrode with 17.3% carbon content exhibits the highest reversible capacity of 1639 mAh g{sup -1} over 100 cycles at a current density of 100 mA g{sup -1} and maintains the best discharge capacity of 782 mAh g{sup -1} over 400 cycles at a current density of 400 mA g{sup -1} for reported In{sub 2}O{sub 3} based anode materials to date. - Highlights: • Monodisperse carbon/In{sub 2}O{sub 3} nanosheet composites have been synthesized via D-fructose-assisted solvothermal approach. • The prepared electrode exhibited high reversible discharge capacity of 1639 mAh g{sup -1} over 100 cycles. • The prepared electrode maintained the discharge capacity of 782 mAh g{sup -1} over 400 cycles at 400 mA g{sup -1}.

  18. Nanostructural and magnetic studies of virtually monodispersed NiFe2O4 nanocrystals synthesized by a liquid–solid-solution assisted hydrothermal route

    International Nuclear Information System (INIS)

    Li Xinghua; Tan Guoguo; Chen Wei; Zhou Baofan; Xue Desheng; Peng Yong; Li, Fashen; Mellors, Nigel J.

    2012-01-01

    This study presents a comprehensively and systematically structural, chemical and magnetic characterization of ∼9.5 nm virtually monodispersed nickel ferrite (NiFe 2 O 4 ) nanoparticles prepared using a modified liquid–solid-solution (LSS) assisted hydrothermal method. Lattice-resolution scanning transmission electron microscope (STEM) and converged beam electron diffraction pattern (CBED) techniques are adapted to characterize the detailed spatial morphology and crystal structure of individual NiFe 2 O 4 particles at nano scale for the first time. It is found that each NiFe 2 O 4 nanoparticle is single crystal with an fcc structure. The morphology investigation reveals that the prepared NiFe 2 O 4 nanoparticles of which the surfaces are decorated by oleic acid are dispersed individually in hexane. The chemical composition of nickel ferrite nanoparticles is measured to be 1:2 atomic ratio of Ni:Fe, indicating a pure NiFe 2 O 4 composition. Magnetic measurements reveal that the as-synthesized nanocrystals displayed superparamagnetic behavior at room temperature and were ferromagnetic at 10 K. The nanoscale characterization and magnetic investigation of monodispersed NiFe 2 O 4 nanoparticles should be significant for its potential applications in the field of biomedicine and magnetic fluid using them as magnetic materials.

  19. Monodisperse colloidal spheres for (Y,Eu2O3 red-emitting phosphors: establishment of processing window and size-dependent luminescence behavior

    Directory of Open Access Journals (Sweden)

    Qi Zhu, Ji-Guang Li, Xiaodong Li, Xudong Sun and Yoshio Sakka

    2011-01-01

    Full Text Available The urea-based homogeneous precipitation method was introduced in the preparation of monodisperse colloidal spheres for (Y0.95Eu0.052O3 red-emitting phosphors, and the processing window was defined. Particle size and shape are significantly affected by the ion concentration and the urea/RE3+ molar ratio R (RE3+=Y3++Eu3+. A low ion concentration is beneficial in forming monodisperse spheres and extending their formation domain. Increasing R results in a gradual change in the composition of spherical particles from the core-shell Eu(OHCO3@Y(OHCO3 structure to a homogeneous solid solution, thereby significantly lowering the calcination temperature at which precursors convert to oxides. Upon UV excitation into the charge-transfer band at 254 nm, the uniform phosphor spheres of (Y0.95Eu0.052O3 exhibit typical red emissions at 613 nm; the emission is stronger from larger particles mainly because of their smaller surface area. Both the luminescence intensity and quantum efficiency of the oxide phosphors increase with elevated calcination temperatures. The spherical shape and excellent dispersion of the precursor particles (~450 nm in diameter have been well retained after calcination at 1000 circleC for 4 h, and the resultant oxide phosphors exhibit external and internal quantum efficiencies of 50 and 82%, respectively.

  20. A novel monodisperse SiO2@C-dot for the rapid and facile identification of latent fingermarks using self-quenching resistant solid-state fluorescence.

    Science.gov (United States)

    Peng, Di; Liu, Xiang; Huang, Mengjun; Wang, Dan; Liu, Renlong

    2018-04-24

    Solid powder fluorescence shows great potential for application in medicine, biology, and engineering, especially in the identification of latent fingermarks in forensic science. However, conventional developing methods suffer from some drawbacks, such as low contrast, low sensitivity, low selectivity, and high toxicity. To conquer these challenges, novel SiO2@C-dot microspheres were prepared via a facile one-pot hydrothermal method by using citric acid as a carbon source and aminosilane as a nitrogen source. Interestingly, the results showed that the resultant powders possess good monodispersity, high fluorescence emission, and resistance to self-quenching. Additionally, the mechanism for the solid-state fluorescence of SiO2@C-dot compounds was also investigated. More importantly, the fingermarks on various surfaces, including transparent glasses, ceramic tiles, transparent plastics, aluminum alloys, plastic cards, painted woods, artificial leathers, and Chinese paper money, developed by the powders have indicated well-defined papillary ridges under a 365 nm UV lamp. The novel strategy of using monodisperse SiO2@C-dot microspheres as a fluorescent label for developing latent fingermarks showed greater advantages compared to conventional methods, which was also demonstrated using the automatic fingerprint identification system. It is simple, rapid, low-cost, nontoxic, and effective, and is expected to be a promising alternative for the development of latent fingerprints in forensic science.

  1. Accessible solitons of fractional dimension

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Wei-Ping, E-mail: zhongwp6@126.com [Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300 (China); Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Belić, Milivoj [Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Zhang, Yiqi [Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, Xi’an Jiaotong University, Xi’an 710049 (China)

    2016-05-15

    We demonstrate that accessible solitons described by an extended Schrödinger equation with the Laplacian of fractional dimension can exist in strongly nonlocal nonlinear media. The soliton solutions of the model are constructed by two special functions, the associated Legendre polynomials and the Laguerre polynomials in the fraction-dimensional space. Our results show that these fractional accessible solitons form a soliton family which includes crescent solitons, and asymmetric single-layer and multi-layer necklace solitons. -- Highlights: •Analytic solutions of a fractional Schrödinger equation are obtained. •The solutions are produced by means of self-similar method applied to the fractional Schrödinger equation with parabolic potential. •The fractional accessible solitons form crescent, asymmetric single-layer and multilayer necklace profiles. •The model applies to the propagation of optical pulses in strongly nonlocal nonlinear media.

  2. Fractional Calculus and Shannon Wavelet

    Directory of Open Access Journals (Sweden)

    Carlo Cattani

    2012-01-01

    Full Text Available An explicit analytical formula for the any order fractional derivative of Shannon wavelet is given as wavelet series based on connection coefficients. So that for any 2(ℝ function, reconstructed by Shannon wavelets, we can easily define its fractional derivative. The approximation error is explicitly computed, and the wavelet series is compared with Grünwald fractional derivative by focusing on the many advantages of the wavelet method, in terms of rate of convergence.

  3. Fractional variational principles in action

    Energy Technology Data Exchange (ETDEWEB)

    Baleanu, Dumitru [Department of Mathematics and Computer Science, Faculty of Art and Sciences, Cankaya University, 06530 Ankara (Turkey); Institute of Space Sciences, PO Box MG-23, R 76900, Magurele-Bucharest (Romania)], E-mail: dumitru@cankaya.edu.tr

    2009-10-15

    The fractional calculus has gained considerable importance in various fields of science and engineering, especially during the last few decades. An open issue in this emerging field is represented by the fractional variational principles area. Therefore, the fractional Euler-Lagrange and Hamilton equations started to be examined intensely during the last decade. In this paper, we review some new trends in this field and we discuss some of their potential applications.

  4. Fractional quiver W-algebras

    Science.gov (United States)

    Kimura, Taro; Pestun, Vasily

    2018-04-01

    We introduce quiver gauge theory associated with the non-simply laced type fractional quiver and define fractional quiver W-algebras by using construction of Kimura and Pestun (Lett Math Phys, 2018. https://doi.org/10.1007/s11005-018-1072-1; Lett Math Phys, 2018. https://doi.org/10.1007/s11005-018-1073-0) with representation of fractional quivers.

  5. On the Fractional Mean Value

    OpenAIRE

    Hosseinabadi, Abdolali Neamaty; Nategh, Mehdi

    2014-01-01

    This work, dealt with the classical mean value theorem and took advantage of it in the fractional calculus. The concept of a fractional critical point is introduced. Some sufficient conditions for the existence of a critical point is studied and an illustrative example rele- vant to the concept of the time dilation effect is given. The present paper also includes, some connections between convexity (and monotonicity) with fractional derivative in the Riemann-Liouville sense.

  6. Fractionated Spacecraft Architectures Seeding Study

    National Research Council Canada - National Science Library

    Mathieu, Charlotte; Weigel, Annalisa

    2006-01-01

    .... Models were developed from a customer-centric perspective to assess different fractionated spacecraft architectures relative to traditional spacecraft architectures using multi-attribute analysis...

  7. Can a sponge fractionate isotopes?

    Science.gov (United States)

    Patel, B; Patel, S; Balani, M C

    1985-03-22

    The study has unequivocally demonstrated that siliceous sponges Spirastrella cuspidifera and Prostylyssa foetida from the same microecological niche exhibit a high degree of species specificity, while accumulating a host of heavy metal ions (Ni, Cr, Cd, Sn, Ti, Mo, Zr). S. cuspidifera accumulated, in addition, 60Co and 63Ni, showing discrimination against other radionuclides, 137Cs and 131I, present in the ambient waters receiving controlled low level waste discharges from a B.W.R. nuclear power station. P. foetida, on the other hand, accumulated only 131I and showed discrimination against other radionuclides including 60Co, although the stable iodine concentrations in both the sponges were the same. The specific activity of 60Co (in becquerels per gram of 59Co) in S. cuspidifera and 131I (in becquerels per gram of 127I) in P. foetida were at least two orders of magnitude greater than in the ambient sea water. That of 63Ni (in becquerels per gram of 62Ni) in S. cuspidifera, on the other hand, was lower by two orders of magnitude than in either abiotic matrices from the same environment. Thus, not only did both the species show bioaccumulation of a specific element, but also preferential uptake of isotopes of the same element, though they were equally available for intake. Such differential uptake of isotopes can possibly be explained in terms of two quite different mechanisms operating, each applicable in a particular case. One is that the xenobiotic isotope enters the environment in a physicochemical form or as a complex different from that of its natural counterpart. If equilibration with the latter is slow, so that the organism acquires the xenobiotic in an unfamiliar chemical context, it may treat it as a chemically distinct entity so that its concentration factor differs from that of stable isotope, thus changing the specific activity. Alternatively, if the xenobiotic is present in the same chemical form as the stable isotope, the only way in which specific

  8. Vertically distinct microbial communities in the Mariana and Kermadec trenches

    Science.gov (United States)

    Donaldson, Sierra; Osuntokun, Oladayo; Xia, Qing; Nelson, Alex; Blanton, Jessica; Allen, Eric E.; Church, Matthew J.; Bartlett, Douglas H.

    2018-01-01

    Hadal trenches, oceanic locations deeper than 6,000 m, are thought to have distinct microbial communities compared to those at shallower depths due to high hydrostatic pressures, topographical funneling of organic matter, and biogeographical isolation. Here we evaluate the hypothesis that hadal trenches contain unique microbial biodiversity through analyses of the communities present in the bottom waters of the Kermadec and Mariana trenches. Estimates of microbial protein production indicate active populations under in situ hydrostatic pressures and increasing adaptation to pressure with depth. Depth, trench of collection, and size fraction are important drivers of microbial community structure. Many putative hadal bathytypes, such as members related to the Marinimicrobia, Rhodobacteraceae, Rhodospirilliceae, and Aquibacter, are similar to members identified in other trenches. Most of the differences between the two trench microbiomes consists of taxa belonging to the Gammaproteobacteria whose distributions extend throughout the water column. Growth and survival estimates of representative isolates of these taxa under deep-sea conditions suggest that some members may descend from shallower depths and exist as a potentially inactive fraction of the hadal zone. We conclude that the distinct pelagic communities residing in these two trenches, and perhaps by extension other trenches, reflect both cosmopolitan hadal bathytypes and ubiquitous genera found throughout the water column. PMID:29621268

  9. COMMERCIAL SNF ACCIDENT RELEASE FRACTIONS

    Energy Technology Data Exchange (ETDEWEB)

    S.O. Bader

    1999-10-18

    The purpose of this design analysis is to specify and document the total and respirable fractions for radioactive materials that are released from an accident event at the Monitored Geologic Repository (MGR) involving commercial spent nuclear fuel (CSNF) in a dry environment. The total and respirable release fractions will be used to support the preclosure licensing basis for the MGR. The total release fraction is defined as the fraction of total CSNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. The radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses. This subset of the total release fraction is referred to as the respirable release fraction. Potential accidents may involve waste forms that are characterized as either bare (unconfined) fuel assemblies or confined fuel assemblies. The confined CSNF assemblies at the MGR are contained in shipping casks, canisters, or disposal containers (waste packages). In contrast to the bare fuel assemblies, the container that confines the fuel assemblies has the potential of providing an additional barrier for diminishing the total release fraction should the fuel rod cladding breach during an accident. However, this analysis will not take credit for this additional bamer and will establish only the total release fractions for bare unconfined CSNF assemblies, which may however be

  10. COMMERCIAL SNF ACCIDENT RELEASE FRACTIONS

    International Nuclear Information System (INIS)

    S.O. Bader

    1999-01-01

    The purpose of this design analysis is to specify and document the total and respirable fractions for radioactive materials that are released from an accident event at the Monitored Geologic Repository (MGR) involving commercial spent nuclear fuel (CSNF) in a dry environment. The total and respirable release fractions will be used to support the preclosure licensing basis for the MGR. The total release fraction is defined as the fraction of total CSNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. The radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses. This subset of the total release fraction is referred to as the respirable release fraction. Potential accidents may involve waste forms that are characterized as either bare (unconfined) fuel assemblies or confined fuel assemblies. The confined CSNF assemblies at the MGR are contained in shipping casks, canisters, or disposal containers (waste packages). In contrast to the bare fuel assemblies, the container that confines the fuel assemblies has the potential of providing an additional barrier for diminishing the total release fraction should the fuel rod cladding breach during an accident. However, this analysis will not take credit for this additional bamer and will establish only the total release fractions for bare unconfined CSNF assemblies, which may however be

  11. Fractions, Number Lines, Third Graders

    Science.gov (United States)

    Cramer, Kathleen; Ahrendt, Sue; Monson, Debra; Wyberg, Terry; Colum, Karen

    2017-01-01

    The Common Core State Standards for Mathematics (CCSSM) (CCSSI 2010) outlines ambitious goals for fraction learning, starting in third grade, that include the use of the number line model. Understanding and constructing fractions on a number line are particularly complex tasks. The current work of the authors centers on ways to successfully…

  12. Unwrapping Students' Ideas about Fractions

    Science.gov (United States)

    Lewis, Rebecca M.; Gibbons, Lynsey K.; Kazemi, Elham; Lind, Teresa

    2015-01-01

    Supporting students to develop an understanding of the meaning of fractions is an important goal of elementary school mathematics. This involves developing partitioning strategies, creating representations, naming fractional quantities, and using symbolic notation. This article describes how teachers can use a formative assessment problem to…

  13. Understanding Magnitudes to Understand Fractions

    Science.gov (United States)

    Gabriel, Florence

    2016-01-01

    Fractions are known to be difficult to learn and difficult to teach, yet they are vital for students to have access to further mathematical concepts. This article uses evidence to support teachers employing teaching methods that focus on the conceptual understanding of the magnitude of fractions.

  14. Financial Planning with Fractional Goals

    OpenAIRE

    Goedhart, Marc; Spronk, Jaap

    1995-01-01

    textabstractWhen solving financial planning problems with multiple goals by means of multiple objective programming, the presence of fractional goals leads to technical difficulties. In this paper we present a straightforward interactive approach for solving such linear fractional programs with multiple goal variables. The approach is illustrated by means of an example in financial planning.

  15. Deterministic ratchets for suspension fractionation

    NARCIS (Netherlands)

    Kulrattanarak, T.

    2010-01-01

    Driven by the current insights in sustainability and technological development in
    biorefining natural renewable resources, the food industry has taken an interest in
    fractionation of agrofood materials, like milk and cereal crops. The purpose of fractionation
    is to split the raw

  16. Fermion fractionization and index theorem

    International Nuclear Information System (INIS)

    Hirayama, Minoru; Torii, Tatsuo

    1982-01-01

    The relation between the fermion fractionization and the Callias-Bott-Seeley index theorem for the Dirac operator in the open space of odd dimension is clarified. Only the case of one spatial dimension is discussed in detail. Sum rules for the expectation values of various quantities in fermion-fractionized configurations are derived. (author)

  17. A new fractional wavelet transform

    Science.gov (United States)

    Dai, Hongzhe; Zheng, Zhibao; Wang, Wei

    2017-03-01

    The fractional Fourier transform (FRFT) is a potent tool to analyze the time-varying signal. However, it fails in locating the fractional Fourier domain (FRFD)-frequency contents which is required in some applications. A novel fractional wavelet transform (FRWT) is proposed to solve this problem. It displays the time and FRFD-frequency information jointly in the time-FRFD-frequency plane. The definition, basic properties, inverse transform and reproducing kernel of the proposed FRWT are considered. It has been shown that an FRWT with proper order corresponds to the classical wavelet transform (WT). The multiresolution analysis (MRA) associated with the developed FRWT, together with the construction of the orthogonal fractional wavelets are also presented. Three applications are discussed: the analysis of signal with time-varying frequency content, the FRFD spectrum estimation of signals that involving noise, and the construction of fractional Harr wavelet. Simulations verify the validity of the proposed FRWT.

  18. Generalized fractional Schroedinger equation with space-time fractional derivatives

    International Nuclear Information System (INIS)

    Wang Shaowei; Xu Mingyu

    2007-01-01

    In this paper the generalized fractional Schroedinger equation with space and time fractional derivatives is constructed. The equation is solved for free particle and for a square potential well by the method of integral transforms, Fourier transform and Laplace transform, and the solution can be expressed in terms of Mittag-Leffler function. The Green function for free particle is also presented in this paper. Finally, we discuss the relationship between the cases of the generalized fractional Schroedinger equation and the ones in standard quantum

  19. Permutation entropy of fractional Brownian motion and fractional Gaussian noise

    International Nuclear Information System (INIS)

    Zunino, L.; Perez, D.G.; Martin, M.T.; Garavaglia, M.; Plastino, A.; Rosso, O.A.

    2008-01-01

    We have worked out theoretical curves for the permutation entropy of the fractional Brownian motion and fractional Gaussian noise by using the Bandt and Shiha [C. Bandt, F. Shiha, J. Time Ser. Anal. 28 (2007) 646] theoretical predictions for their corresponding relative frequencies. Comparisons with numerical simulations show an excellent agreement. Furthermore, the entropy-gap in the transition between these processes, observed previously via numerical results, has been here theoretically validated. Also, we have analyzed the behaviour of the permutation entropy of the fractional Gaussian noise for different time delays

  20. Laboratory sol-gel preparation of fine fraction of sintered uranium dioxide spheres

    International Nuclear Information System (INIS)

    Landspersky, H.; Tympl, M.

    1984-01-01

    The results are summed up of the laboratory investigation of preparing the fine fraction of sintered uranium dioxide particles from uranyl gel using the method of the mixed reactor and the method of the dual-liquid nozzle, processed by leaching, drying, calcination and sintering. None of the two methods provides monodispersion particles under the given conditions but better control of the throughflow of the liquid media may improve results. Leaching of the fine fraction is very quick and the leaching of most components takes no longer than 5 minutes. In view of the fact that leaching of all components does not proceed at the same rate it is recommended that leaching time be doubled, or that leaching take place in two stages. Azeotropic distillation with chlorinated hydrocarbons is a favourable procedure for obtaining quality material; it is, however, necessary to prevent dried particles from comino. into contact with the water phase condensing on the walls of the distillation vessel and running down onto the surface of the distilling mixture. Calcination at a temperature of 500 degC in a thin layer and sintering at temperatures between 1350 and 1550 degC at an adequate rate of inflow of gaseous media and adequate rate of outflow of reaction wastes results in the production of high quality material whose density exceeds 97 to 98% theoretical density. (author)

  1. Tunable solvation effects on the size-selective fractionation of metal nanoparticles in CO2 gas-expanded solvents.

    Science.gov (United States)

    Anand, Madhu; McLeod, M Chandler; Bell, Philip W; Roberts, Christopher B

    2005-12-08

    This paper presents an environmentally friendly, inexpensive, rapid, and efficient process for size-selective fractionation of polydisperse metal nanoparticle dispersions into multiple narrow size populations. The dispersibility of ligand-stabilized silver and gold nanoparticles is controlled by altering the ligand tails-solvent interaction (solvation) by the addition of carbon dioxide (CO2) gas as an antisolvent, thereby tailoring the bulk solvent strength. This is accomplished by adjusting the CO2 pressure over the liquid, resulting in a simple means to tune the nanoparticle precipitation by size. This study also details the influence of various factors on the size-separation process, such as the types of metal, ligand, and solvent, as well as the use of recursive fractionation and the time allowed for settling during each fractionation step. The pressure range required for the precipitation process is the same for both the silver and gold particles capped with dodecanethiol ligands. A change in ligand or solvent length has an effect on the interaction between the solvent and the ligand tails and therefore the pressure range required for precipitation. Stronger interactions between solvent and ligand tails require greater CO2 pressure to precipitate the particles. Temperature is another variable that impacts the dispersibility of the nanoparticles through changes in the density and the mole fraction of CO2 in the gas-expanded liquids. Recursive fractionation for a given system within a particular pressure range (solvent strength) further reduces the polydispersity of the fraction obtained within that pressure range. Specifically, this work utilizes the highly tunable solvent properties of organic/CO2 solvent mixtures to selectively size-separate dispersions of polydisperse nanoparticles (2 to 12 nm) into more monodisperse fractions (+/-2 nm). In addition to providing efficient separation of the particles, this process also allows all of the solvent and

  2. Toward lattice fractional vector calculus

    International Nuclear Information System (INIS)

    Tarasov, Vasily E

    2014-01-01

    An analog of fractional vector calculus for physical lattice models is suggested. We use an approach based on the models of three-dimensional lattices with long-range inter-particle interactions. The lattice analogs of fractional partial derivatives are represented by kernels of lattice long-range interactions, where the Fourier series transformations of these kernels have a power-law form with respect to wave vector components. In the continuum limit, these lattice partial derivatives give derivatives of non-integer order with respect to coordinates. In the three-dimensional description of the non-local continuum, the fractional differential operators have the form of fractional partial derivatives of the Riesz type. As examples of the applications of the suggested lattice fractional vector calculus, we give lattice models with long-range interactions for the fractional Maxwell equations of non-local continuous media and for the fractional generalization of the Mindlin and Aifantis continuum models of gradient elasticity. (papers)

  3. Anomalous Symmetry Fractionalization and Surface Topological Order

    Directory of Open Access Journals (Sweden)

    Xie Chen

    2015-10-01

    Full Text Available In addition to possessing fractional statistics, anyon excitations of a 2D topologically ordered state can realize symmetry in distinct ways, leading to a variety of symmetry-enriched topological (SET phases. While the symmetry fractionalization must be consistent with the fusion and braiding rules of the anyons, not all ostensibly consistent symmetry fractionalizations can be realized in 2D systems. Instead, certain “anomalous” SETs can only occur on the surface of a 3D symmetry-protected topological (SPT phase. In this paper, we describe a procedure for determining whether a SET of a discrete, on-site, unitary symmetry group G is anomalous or not. The basic idea is to gauge the symmetry and expose the anomaly as an obstruction to a consistent topological theory combining both the original anyons and the gauge fluxes. Utilizing a result of Etingof, Nikshych, and Ostrik, we point out that a class of obstructions is captured by the fourth cohomology group H^{4}(G,U(1, which also precisely labels the set of 3D SPT phases, with symmetry group G. An explicit procedure for calculating the cohomology data from a SET is given, with the corresponding physical intuition explained. We thus establish a general bulk-boundary correspondence between the anomalous SET and the 3D bulk SPT whose surface termination realizes it. We illustrate this idea using the chiral spin liquid [U(1_{2}] topological order with a reduced symmetry Z_{2}×Z_{2}⊂SO(3, which can act on the semion quasiparticle in an anomalous way. We construct exactly solved 3D SPT models realizing the anomalous surface terminations and demonstrate that they are nontrivial by computing three-loop braiding statistics. Possible extensions to antiunitary symmetries are also discussed.

  4. Ferroelectric Fractional-Order Capacitors

    KAUST Repository

    Agambayev, Agamyrat

    2017-07-25

    Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.

  5. Ferroelectric Fractional-Order Capacitors

    KAUST Repository

    Agambayev, Agamyrat; Patole, Shashikant P.; Farhat, Mohamed; Elwakil, Ahmed; Bagci, Hakan; Salama, Khaled N.

    2017-01-01

    Poly(vinylidene fluoride)-based polymers and their blends are used to fabricate electrostatic fractional-order capacitors. This simple but effective method allows us to precisely tune the constant phase angle of the resulting fractional-order capacitor by changing the blend composition. Additionally, we have derived an empirical relation between the ratio of the blend constituents and the constant phase angle to facilitate the design of a fractional order capacitor with a desired constant phase angle. The structural composition of the fabricated blends is investigated using Fourier transform infrared spectroscopy and X-ray diffraction techniques.

  6. On Generalized Fractional Differentiator Signals

    Directory of Open Access Journals (Sweden)

    Hamid A. Jalab

    2013-01-01

    Full Text Available By employing the generalized fractional differential operator, we introduce a system of fractional order derivative for a uniformly sampled polynomial signal. The calculation of the bring in signal depends on the additive combination of the weighted bring-in of N cascaded digital differentiators. The weights are imposed in a closed formula containing the Stirling numbers of the first kind. The approach taken in this work is to consider that signal function in terms of Newton series. The convergence of the system to a fractional time differentiator is discussed.

  7. Solvent-Mediated Eco-Friendly Synthesis and Characterization of Monodispersed Bimetallic Ag/Pd Nano composites for Sensing and Raman Scattering Applications

    International Nuclear Information System (INIS)

    Sathiyadevi, G.; Loganathan, B.; Karthikeyan, B.; Karthikeyan, B.

    2014-01-01

    The solvent-mediated eco-friendly monodispersed Ag/Pd bimetallic nano composites (BNCs) having thick core and thin shell have been prepared through novel green chemical solvent reduction method. Reducing solvent, dimethyl formamide (DMF) is employed for the controlled green synthesis. Characterization of the synthesized Ag/Pd BNCs has been done by x-ray diffraction (XRD) studies, high-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray analysis (EDX), and high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern. The nature of the interaction of L-cysteine with Ag/Pd BNCs has been studied by using surface plasmon spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and theoretical methods.

  8. Preparation and thermodynamic stability of micron-sized, monodisperse composite polymer particles of disc-like shapes by seeded dispersion polymerization.

    Science.gov (United States)

    Fujibayashi, Teruhisa; Okubo, Masayoshi

    2007-07-17

    Micron-sized, monodisperse composite polymer particles having "disc-like" and "polyhedral" shapes were prepared by seeded dispersion polymerization of 2-ethylhexylmethacrylate (EHMA) with 2.67-mum-sized polystyrene (PS) seed particles in methanol/water media in the presence of droplets of various saturated hydrocarbons and evaporation of the hydrocarbon after the polymerization. Such nonspherical shapes were based on the volume reduction due to the evaporation. The primary factors influencing the particle shape seemed to be the absorption rate of the hydrocarbon into the resulting PS/poly(EHMA)/hydrocarbon composite particles during the polymerization, which affected the viscosities and the volumes of the PS and poly(EHMA) phases. It was found that the morphological development during the polymerization was retarded at "hamburger-like" morphology, which is a precursor of the disc-like particle, although this morphology is a thermodynamically metastable state.

  9. Fabrication of monodispersed nickel flower-like architectures via a solvent-thermal process and analysis of their magnetic and electromagnetic properties

    International Nuclear Information System (INIS)

    Kong Jing; Liu Wei; Wang Fenglong; Wang Xinzhen; Luan Liqiang; Liu Jiurong; Wang Yuan; Zhang Zijun; Itoh, Masahiro; Machida, Ken-ichi

    2011-01-01

    Monodispersed Ni flower-like architectures with size of 1-2 μm were synthesized through a facile solvent-thermal process in 1,2-propanediol solution in the presence of polyethylene glycol (PEG) and sodium alkali for electromagnetic absorption application. The Ni architectures are composed of nanoflakes, which assemble to form three dimensional flower-like structure, and the thickness of nanoflakes is about 10-40 nm. A possible formation mechanism for Ni flower-like architectures was proposed and it was confirmed by the control experiments. The Ni architectures exhibited a saturation magnetization (M s ) of 47.7 emu/g and a large coercivity (H cj ) of 332.3 Oe. The epoxy resin composites with 20 vol% Ni sample provided good electromagnetic wave absorption performance (reflection loss cj ) of 332.3 Oe. → Efficient electromagnetic absorption (RL<-20 dB) was provided in 2.8-6.3 GHz.

  10. Water-resistant, monodispersed and stably luminescent CsPbBr3/CsPb2Br5 core-shell-like structure lead halide perovskite nanocrystals

    Science.gov (United States)

    Qiao, Bo; Song, Pengjie; Cao, Jingyue; Zhao, Suling; Shen, Zhaohui; Gao, Di; Liang, Zhiqin; Xu, Zheng; Song, Dandan; Xu, Xurong

    2017-11-01

    Lead halide perovskite materials are thriving in optoelectronic applications due to their excellent properties, while their instability due to the fact that they are easily hydrolyzed is still a bottleneck for their potential application. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb2Br5 were obtained using a modified non-stoichiometric solution-phase method. CsPb2Br5 2D layers were coated on the surface of CsPbBr3 nanocrystals and formed a core-shell-like structure in the synthetic processes. The stability of the luminescence of the CsPbBr3 nanocrystals in water and ethanol atmosphere was greatly enhanced by the photoluminescence-inactive CsPb2Br5 coating with a wide bandgap. The water-stable enhanced nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.

  11. Experimental study of average void fraction in low-flow subcooled boiling

    International Nuclear Information System (INIS)

    Sun Qi; Wang Xiaojun; Xi Zhao; Zhao Hua; Yang Ruichang

    2005-01-01

    Low-flow subcooled void fraction in medium pressure was investigated using high-temperature high-pressure single-sensor optical probe in this paper. And then average void fraction was obtained through the integral calculation of local void fraction in the cross-section. The experimental data were compared with the void fraction model proposed in advance. The results show that the predictions of this model agree with the data quite well. The comparisons of Saha and Levy models with low-flow subcooled data show that Saha model overestimates the experimental data distinctively, and Levy model also gets relatively higher predictions although it is better than Saha model. (author)

  12. Effect of surfactant amount on the morphology and magnetic properties of monodisperse ZnFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haitao, E-mail: zht95711lunwen@163.com; Liu, Ruiping; Zhang, Qiang; Wang, Qiao

    2016-03-15

    Graphical abstract: Polyol process to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles. - Highlights: • An one-step, facile and inexpensive synthetic route to monodisperse ZnFe{sub 2}O{sub 4} nanoparticles is described. • The sodium citrate stabilized ZnFe{sub 2}O{sub 4} nanoparticles with a diameter in the 5–8 nm size range can be easily dispersed in water. • The synthesis is very robust in terms of variations of experimental parameters. • ZnFe{sub 2}O{sub 4} nanoparticles present ferrimagnetic behavior at room temperature with a small hysteresis. - Abstract: The spinel ZnFe{sub 2}O{sub 4} ferrites with sodium citrate as a surfactant were fabricated by polyol process. The effect of surfactant amount on the structure, morphology and magnetic properties of ZnFe{sub 2}O{sub 4} ferrites were investigated by X-ray diffraction(XRD), transmission electron microscope (TEM), thermogravimetric and differential scanning calorimetry (TG–DSC) and vibrating sample magnetometry (VSM), respectively. The results indicate that the structure of ZnFe{sub 2}O{sub 4} ferrites is a pure cubic spinel structure with a particle size of 5–8 nm. The dispersion of the synthesized ZnFe{sub 2}O{sub 4} is enhanced when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases. The synthesized particles present ferrimagnetic behavior with a small hysteresis at room temperature. The increase of surfactant amount conversely leads to the decrease in the saturation magnetization value (Ms) especially when the mole ratio of Fe(acac){sub 3} to sodium citrate decreases to 8:3. Its Ms value is drastically reduced to 18.97 emu/g.

  13. Crossflow type silicon microchannel substrate monodispersion oil-in-water emulsion manufacture; Kurosufuro gata shirikon maikuro chaneru kiban wo mochiita tanbunsan suchuyu emarushon no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, Takahiro [Tohoku University, Miyagi (Japan). Graduate School; Komori, Hideai; Najima, Mitsutashi; Kikuchi, Yuji; Yonemoto, Toshikuni

    1999-05-05

    The new technique, which continuously produced the monodispersion oil-in-water (0/W) emulsion using the crossflow type silicon microchannel substrate, was developed. On the silicon monocrystal substrate, the watercourse as the liquid of the continuous phase flowed was produced, and the column of the equal slit of the size in both walls of the watercourse was precisely processed. By closing the upper part in the slit by the clamp of the flat glass board in the microchannel substrate, the microchannel column was formed. Through the microchannel, the oil droplet in which the size was even was formed by sending out the oil (triolein) in the water (0.3wt% sodium lauryl sulfate aqueous solution) of continuous phase which is flowing in respect of the watercourse. The size of the oil droplet is greatly dependent on the structure of the microchannel regulated by microchannel width, microchannel height and terrace length (the even part of which the microchannel exit was equipped). Monodispersion emulsion of 16,20 and 48 {mu}m at the average droplet diameter was formed by using microchannel substrate of the three types of which the structure differs. Droplet diameter decreased, when the substrate which formed large droplet of 48 {mu}m in which the water current quantity is 1.4x10{sup -2}mLmin{sup -1} was used, when the flow rate increased. However, there was no a flow rate at droplet diameter, even if it was made to change from 1.4x10{sup -2} to 2.4mLmin{sup -1}, 16 {mu}m 20 {mu}m small change. In all cases, the droplet size distribution was narrow, and the geometry standard deviation was under 1.03. (translated by NEDO)

  14. UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

    Science.gov (United States)

    Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

    2014-10-01

    Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

  15. Development of new ionic gelation strategy: Towards the preparation of new monodisperse and stable hyaluronic acid/β-cyclodextrin-grafted chitosan nanoparticles as drug delivery carriers for doxorubicin

    Science.gov (United States)

    Mihoub, Amina Ben; Saidat, Boubakeur; Bal, Youssef; Frochot, Céline; Vanderesse, Régis; Acherar, Samir

    2018-03-01

    In the present study, β-cyclodextrin-grafted chitosan nanoparticles (β-CD- g-CS NPs) were prepared using a new ionic gelation strategy involving a synergistic effect of NaCl (150 mmol/L), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES, 10 mmol/L), and water bath sonication. This new strategy afforded smaller and more monodisperse β-CD- g-CS NPs vs. the classical ionic gelation method. New HA/β-CD- g-CS NPs were also prepared using the above-mentioned strategy by adding hyaluronic acid (HA) to the β-CD- g-CS copolymer at different weight ratios until the ZP values conversion. The best result was obtained with the weight ratio of w(HA): w(β-CD- g-CS) = 2:1 and furnished new spherical and smooth HA/β-CD- g-CS NPs. Furthermore, the stability of β- CD- g-CS NPs and HA/β-CD- g-CS NPs at 4°C in physiological medium (pH 7.4) was compared for 3 weeks period and showed that HA/β-CD- g-CS NPs were more stable all maintaining their monodispersity and high negative ZP values compared to β-CD- g-CS NPs. Finally, preliminary study of HA/β-CD- g-CS NPs as carrier for the controlled release of the anticancer drug doxorubicin was investigated. These new HA/β-CD- g-CS NPs can potentially be used as drug delivery and targeting systems for cancer treatment.

  16. Annealing effect on the structural and optical properties of Cr/α-Cr2O3 monodispersed particles based solar absorbers

    International Nuclear Information System (INIS)

    Khamlich, S.; McCrindle, R.; Nuru, Z.Y.; Cingo, N.; Maaza, M.

    2013-01-01

    Graphical abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. Highlights: ► Cr/α-Cr 2 O 3 have been deposited by the aqueous chemical growth (ACG) method. ► High temperature annealing affects the optical selectivity of the deposited particles. ► Oxygen diffusion to the interface at high temperature results in the oxidization of the substrate. - Abstract: A cost-effective and environmentally friendly green chemical method, the so-called aqueous chemical growth (ACG) method, was used to deposit chromium/alpha-chromium(III) oxide, Cr/α-Cr 2 O 3 , monodispersed particles, for solar absorbers applications. The deposited particles were annealed at various temperatures in a hydrogen atmosphere for 2 h to study the annealing temperature dependence of the structural, chemical and optical properties of the particles grown on tantalum substrates. The deposited Cr/α-Cr 2 O 3 was characterized by X-ray diffraction (XRD), attenuated total reflection (ATR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and diffuse reflectance UV–vis–NIR spectroscopy. The XRD and ATR analysis indicated that by increasing annealing temperature, the particles crystallinity was improved and Ta 2 O 5 was formed around 600 °C, due to the fast oxygen diffusion from the deposited α-Cr 2 O 3 toward the tantalum substrate. The optical measurements show that samples annealed at 400 and 500 °C exhibit the targeted high absorbing optical characteristics of “Black chrome”, while those annealed below 400 °C and above 500 °C show a significant low absorptivity and high emissivity.

  17. Synthesis of raspberry-like monodisperse magnetic hollow hybrid nanospheres by coating polystyrene template with Fe(3)O(4)@SiO(2) particles.

    Science.gov (United States)

    Wang, Chunlei; Yan, Juntao; Cui, Xuejun; Wang, Hongyan

    2011-02-01

    In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe(2)O(3)@SiO(2) particles as the outer shell. PS@Fe(3)O(4)@SiO(2) composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe(3)O(4)) was transformed into maghemite (γ-Fe(2)O(3)). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe(3)O(4) in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption-desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5-5.5nm, 307m(2)g(-1) and 1.33cm(3)g(-1), respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Synthesis of monodisperse MFe{sub 2}O{sub 4} (M = Fe and Zn) nanoparticles for polydiethylsiloxane-based ferrofluid with a solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Zhuang, Lin, E-mail: stszhl@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Zhang, Yong [Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Shen, Hui [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2015-09-15

    Highlights: • MFe{sub 2}O{sub 4} nanoparticles were synthesized through a facile solvothermal method. • The relationship between viscosity and temperature of the polydiethylsiloxane-based ferrofluid is discussed. • Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 73.06 emu/g at room temperature. - Abstract: Monodisperse MFe{sub 2}O{sub 4} (M = Fe, Zn) nanoparticles were successfully synthesized for the application of polydiethylsiloxane-based (PDES) ferrofluids (FFs) via a novel solvothermal method, with which 1-octanol and 1-octanamine act as binary solvent, oleic acid (OA) as the surfactant and metal acetylacetonate [M(acac){sub 3}](M = Fe and Zn) as the metal source. X-ray diffractometer confirms that the resultant nanoparticles are pure MFe{sub 2}O{sub 4} with a spinel structure. Infrared spectroscopy indicates that oleic acid is bound to the surface of MFe{sub 2}O{sub 4} through a covalent bond between carboxylate (COO{sup −}) and metal cations. The ratio of 1-octanol and 1-octanamine plays a key role in the formation of the sphere-shaped morphology. Transmission electron microscopy (TEM) images confirm that the Fe{sub 3}O{sub 4} particles are of 4–11 nm with good monodispersity and a narrow size distribution. The saturation magnetization of Fe{sub 3}O{sub 4} nanoparticles with sizes of 7 nm can reach up to 73.06 emu/g. Polydiethylsiloxane-based (PDES) FFs show relatively smaller changes of the viscosity with low temperatures (from −7 to 20 °C) than the polydimethylsiloxane-based (PDMS) FFs. For FFs applications, the relationship between viscosity and temperature is also discussed.

  19. On generalized fractional vibration equation

    International Nuclear Information System (INIS)

    Dai, Hongzhe; Zheng, Zhibao; Wang, Wei

    2017-01-01

    Highlights: • The paper presents a generalized fractional vibration equation for arbitrary viscoelastically damped system. • Some classical vibration equations can be derived from the developed equation. • The analytic solution of developed equation is derived under some special cases. • The generalized equation is particularly useful for developing new fractional equivalent linearization method. - Abstract: In this paper, a generalized fractional vibration equation with multi-terms of fractional dissipation is developed to describe the dynamical response of an arbitrary viscoelastically damped system. It is shown that many classical equations of motion, e.g., the Bagley–Torvik equation, can be derived from the developed equation. The Laplace transform is utilized to solve the generalized equation and the analytic solution under some special cases is derived. Example demonstrates the generalized transfer function of an arbitrary viscoelastic system.

  20. Physcicists rewarded for 'fractional electrons'

    CERN Multimedia

    Ball, P

    1998-01-01

    The 1998 Nobel prize for physics has been awarded to Horst Stormer, Daniel Tsui and Robert Laughlin.Stormer and Tsui were the first to observe the fractional quantum Hall effect and Laughlin provided the theory shortly afterwards (1 page).

  1. Ultracentrifugation for ultrafine nanodiamond fractionation

    Science.gov (United States)

    Koniakhin, S. V.; Besedina, N. A.; Kirilenko, D. A.; Shvidchenko, A. V.; Eidelman, E. D.

    2018-01-01

    In this paper we propose a method for ultrafine fractionation of nanodiamonds using the differential centrifugation in the fields up to 215000g. The developed protocols yield 4-6 nm fraction giving main contribution to the light scattering intensity. The desired 4-6 nm fraction can be obtained from various types of initial nanodiamonds: three types of detonation nanodiamonds differing in purifying methods, laser synthesis nanodiamonds and nanodiamonds made by milling. The characterization of the obtained hydrosols was conducted with Dynamic Light Scattering, Zeta potential measurements, powder XRD and TEM. According to powder XRD and TEM data ultracentrifugation also leads to a further fractionation of the primary diamond nanocrystallites in the hydrosols from 4 to 2 nm.

  2. Social conformity despite individual preferences for distinctiveness.

    Science.gov (United States)

    Smaldino, Paul E; Epstein, Joshua M

    2015-03-01

    We demonstrate that individual behaviours directed at the attainment of distinctiveness can in fact produce complete social conformity. We thus offer an unexpected generative mechanism for this central social phenomenon. Specifically, we establish that agents who have fixed needs to be distinct and adapt their positions to achieve distinctiveness goals, can nevertheless self-organize to a limiting state of absolute conformity. This seemingly paradoxical result is deduced formally from a small number of natural assumptions and is then explored at length computationally. Interesting departures from this conformity equilibrium are also possible, including divergence in positions. The effect of extremist minorities on these dynamics is discussed. A simple extension is then introduced, which allows the model to generate and maintain social diversity, including multimodal distinctiveness distributions. The paper contributes formal definitions, analytical deductions and counterintuitive findings to the literature on individual distinctiveness and social conformity.

  3. Commercial SNF Accident Release Fractions

    Energy Technology Data Exchange (ETDEWEB)

    J. Schulz

    2004-11-05

    The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M&O 1999). In contrast to bare unconfined fuel assemblies, the

  4. Commercial SNF Accident Release Fractions

    International Nuclear Information System (INIS)

    Schulz, J.

    2004-01-01

    The purpose of this analysis is to specify and document the total and respirable fractions for radioactive materials that could be potentially released from an accident at the repository involving commercial spent nuclear fuel (SNF) in a dry environment. The total and respirable release fractions are used to support the preclosure licensing basis for the repository. The total release fraction is defined as the fraction of total commercial SNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. Radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses; this subset of the total release fraction is referred to as the respirable release fraction. Accidents may involve waste forms characterized as: (1) bare unconfined intact fuel assemblies, (2) confined intact fuel assemblies, or (3) canistered failed commercial SNF. Confined intact commercial SNF assemblies at the repository are contained in shipping casks, canisters, or waste packages. Four categories of failed commercial SNF are identified: (1) mechanically and cladding-penetration damaged commercial SNF, (2) consolidated/reconstituted assemblies, (3) fuel rods, pieces, and debris, and (4) nonfuel components. It is assumed that failed commercial SNF is placed into waste packages with a mesh screen at each end (CRWMS M andO 1999). In contrast to bare unconfined fuel assemblies, the

  5. Fractional Reserve Banking: Some Quibbles

    OpenAIRE

    Bagus, Philipp; Howden, David

    2010-01-01

    We explore several unaddressed issues in George Selgin’s (1988) claim that the best monetary system to maintain monetary equilibrium is a fractional reserve free banking one. The claim that adverse clearing balances would limit credit expansion in a fractional reserve free banking system is more troublesome than previously reckoned. Both lengthened clearing periods and interbank agreements render credit expansion unrestrained. “The theory of free banking” confuses increases in money held with...

  6. Intelligent fractions learning system: implementation

    CSIR Research Space (South Africa)

    Smith, Andrew C

    2011-05-01

    Full Text Available Conference Proceedings Paul Cunningham and Miriam Cunningham (Eds) IIMC International Information Management Corporation, 2011 ISBN: 978-1-905824-24-3 An Intelligent Fractions Learning System: Implementation Andrew Cyrus SMITH1, Teemu H. LAINE2 1CSIR... to fractions. Our aim with the current research project is to extend the existing UFractions learning system to incorporate automatic data capturing. ?Intelligent UFractions? allows a teacher to remotely monitor the children?s progress during...

  7. Fractional Charge Definitions and Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Goldhaber, A.S.

    2004-06-04

    Fractional charge is known through theoretical and experimental discoveries of isolable objects carrying fractions of familiar charge units--electric charge Q, spin S, and the difference of baryon and lepton numbers B-L. With a few simple assumptions all these effects may be described using a generalized version of charge renormalization for locally conserved charges, in which medium correlations yield familiar adiabatic, continuous renormalization, or sometimes nonadiabatic, discrete renormalization. Fractional charges may be carried by fundamental particles or fundamental solitons. Either picture works for the simplest fractional-quantum-Hall-effect quasiholes, though the particle description is far more general. The only known fundamental solitons in three or fewer space dimensions d are the kink (d = 1), the vortex (d = 2), and the magnetic monopole (d = 3). Further, for a charge not intrinsically coupled to the topological charge of a soliton, only the kink and the monopole may carry fractional values. The same reasoning enforces fractional values of B-L for electrically charged elementary particles.

  8. Fractional Charge Definitions and Conditions

    International Nuclear Information System (INIS)

    Goldhaber, A.S.

    2004-01-01

    Fractional charge is known through theoretical and experimental discoveries of isolable objects carrying fractions of familiar charge units--electric charge Q, spin S, and the difference of baryon and lepton numbers B-L. With a few simple assumptions all these effects may be described using a generalized version of charge renormalization for locally conserved charges, in which medium correlations yield familiar adiabatic, continuous renormalization, or sometimes nonadiabatic, discrete renormalization. Fractional charges may be carried by fundamental particles or fundamental solitons. Either picture works for the simplest fractional-quantum-Hall-effect quasiholes, though the particle description is far more general. The only known fundamental solitons in three or fewer space dimensions d are the kink (d = 1), the vortex (d = 2), and the magnetic monopole (d = 3). Further, for a charge not intrinsically coupled to the topological charge of a soliton, only the kink and the monopole may carry fractional values. The same reasoning enforces fractional values of B-L for electrically charged elementary particles

  9. Kinetic isotopic fractionation during diffusion of ionic species in water

    Science.gov (United States)

    Richter, Frank M.; Mendybaev, Ruslan A.; Christensen, John N.; Hutcheon, Ian D.; Williams, Ross W.; Sturchio, Neil C.; Beloso, Abelardo D.

    2006-01-01

    Experiments specifically designed to measure the ratio of the diffusivities of ions dissolved in water were used to determine DLi/DK,D/D,D/D,D/D,andD/D. The measured ratio of the diffusion coefficients for Li and K in water (D Li/D K = 0.6) is in good agreement with published data, providing evidence that the experimental design being used resolves the relative mobility of ions with adequate precision to also be used for determining the fractionation of isotopes by diffusion in water. In the case of Li, we found measurable isotopic fractionation associated with the diffusion of dissolved LiCl (D/D=0.99772±0.00026). This difference in the diffusion coefficient of 7Li compared to 6Li is significantly less than that reported in an earlier study, a difference we attribute to the fact that in the earlier study Li diffused through a membrane separating the water reservoirs. Our experiments involving Mg diffusing in water found no measurable isotopic fractionation (D/D=1.00003±0.00006). Cl isotopes were fractionated during diffusion in water (D/D=0.99857±0.00080) whether or not the co-diffuser (Li or Mg) was isotopically fractionated. The isotopic fractionation associated with the diffusion of ions in water is much smaller than values we found previously for the isotopic fractionation of Li and Ca isotopes by diffusion in molten silicate liquids. A major distinction between water and silicate liquids is that water surrounds dissolved ions with hydration shells, which very likely play an important but still poorly understood role in limiting the isotopic fractionation associated with diffusion.

  10. Fractional Diffusion Equations and Anomalous Diffusion

    Science.gov (United States)

    Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin

    2018-01-01

    Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.

  11. Conformable Fractional Bessel Equation and Bessel Functions

    OpenAIRE

    Gökdoğan, Ahmet; Ünal, Emrah; Çelik, Ercan

    2015-01-01

    In this work, we study the fractional power series solutions around regular singular point x=0 of conformable fractional Bessel differential equation and fractional Bessel functions. Then, we compare fractional solutions with ordinary solutions. In addition, we present certain property of fractional Bessel functions.

  12. Discrete fractional solutions of a Legendre equation

    Science.gov (United States)

    Yılmazer, Resat

    2018-01-01

    One of the most popular research interests of science and engineering is the fractional calculus theory in recent times. Discrete fractional calculus has also an important position in fractional calculus. In this work, we acquire new discrete fractional solutions of the homogeneous and non homogeneous Legendre differential equation by using discrete fractional nabla operator.

  13. Fractional governing equations of transient groundwater flow in confined aquifers with multi-fractional dimensions in fractional time

    OpenAIRE

    M. L. Kavvas; T. Tu; A. Ercan; J. Polsinelli

    2017-01-01

    Using fractional calculus, a dimensionally consistent governing equation of transient, saturated groundwater flow in fractional time in a multi-fractional confined aquifer is developed. First, a dimensionally consistent continuity equation for transient saturated groundwater flow in fractional time and in a multi-fractional, multidimensional confined aquifer is developed. For the equation of water flux within a multi-fractional multidimensional confined aquifer, a dimensionally...

  14. Fractional charge definitions and conditions

    International Nuclear Information System (INIS)

    Goldhaber, Alfred Scharff

    2003-01-01

    The phenomenon of fractional charge has come to prominence in recent decades through theoretical and experimental discoveries of isolable objects which carry fractions of familiar charge units--electric charge Q, spin S, baryon number B and lepton number L. It is shown here on the basis of a few simple assumptions that all these effects may be described using a generalized version of charge renormalization for locally conserved charges, in which many-body correlations can produce familiar adiabatic, continuous renormalization, and in some circumstances nonadiabatic, discrete renormalization. The fractional charges may be carried either by fundamental particles or by fundamental solitons. This excludes nontopological solitons and also skyrmions: The only known fundamental solitons in three or fewer space dimensions d are the kink (d=1), the vortex (d=2), and the magnetic monopole (d=3). Further, for a charge which is not intrinsically coupled to the topological charge of a soliton, only the kink and the monopole may carry fractional values. The same reasoning enforces fractional local values of B-L for electrically charged elementary particles

  15. REFractions: The Representing Equivalent Fractions Game

    Science.gov (United States)

    Tucker, Stephen I.

    2014-01-01

    Stephen Tucker presents a fractions game that addresses a range of fraction concepts including equivalence and computation. The REFractions game also improves students' fluency with representing, comparing and adding fractions.

  16. dimensional generalised time-fractional Hirota equation

    Indian Academy of Sciences (India)

    Youwei Zhang

    2018-02-09

    Feb 9, 2018 ... Fractional calculus has attracted much attention in ... cally proved that the fractional calculus theory is non- ... calculus and various definitions of fractional integration .... basic features of the tanh-expansion are outlined as.

  17. Validity of Sensory Systems as Distinct Constructs

    OpenAIRE

    Su, Chia-Ting; Parham, L. Diane

    2014-01-01

    Confirmatory factor analysis testing whether sensory questionnaire items represented distinct sensory system constructs found, using data from two age groups, that such constructs can be measured validly using questionnaire data.

  18. Visual distinctiveness can enhance recency effects.

    Science.gov (United States)

    Bornstein, B H; Neely, C B; LeCompte, D C

    1995-05-01

    Experimental efforts to meliorate the modality effect have included attempts to make the visual stimulus more distinctive. McDowd and Madigan (1991) failed to find an enhanced recency effect in serial recall when the last item was made more distinct in terms of its color. In an attempt to extend this finding, three experiments were conducted in which visual distinctiveness was manipulated in a different manner, by combining the dimensions of physical size and coloration (i.e., whether the stimuli were solid or outlined in relief). Contrary to previous findings, recency was enhanced when the size and coloration of the last item differed from the other items in the list, regardless of whether the "distinctive" item was larger or smaller than the remaining items. The findings are considered in light of other research that has failed to obtain a similar enhanced recency effect, and their implications for current theories of the modality effect are discussed.

  19. Generalized Multiparameters Fractional Variational Calculus

    Directory of Open Access Journals (Sweden)

    Om Prakash Agrawal

    2012-01-01

    Full Text Available This paper builds upon our recent paper on generalized fractional variational calculus (FVC. Here, we briefly review some of the fractional derivatives (FDs that we considered in the past to develop FVC. We first introduce new one parameter generalized fractional derivatives (GFDs which depend on two functions, and show that many of the one-parameter FDs considered in the past are special cases of the proposed GFDs. We develop several parts of FVC in terms of one parameter GFDs. We point out how many other parts could be developed using the properties of the one-parameter GFDs. Subsequently, we introduce two new two- and three-parameter GFDs. We introduce some of their properties, and discuss how they can be used to develop FVC. In addition, we indicate how these formulations could be used in various fields, and how the generalizations presented here can be further extended.

  20. Semi-infinite fractional programming

    CERN Document Server

    Verma, Ram U

    2017-01-01

    This book presents a smooth and unified transitional framework from generalised fractional programming, with a finite number of variables and a finite number of constraints, to semi-infinite fractional programming, where a number of variables are finite but with infinite constraints. It focuses on empowering graduate students, faculty and other research enthusiasts to pursue more accelerated research advances with significant interdisciplinary applications without borders. In terms of developing general frameworks for theoretical foundations and real-world applications, it discusses a number of new classes of generalised second-order invex functions and second-order univex functions, new sets of second-order necessary optimality conditions, second-order sufficient optimality conditions, and second-order duality models for establishing numerous duality theorems for discrete minmax (or maxmin) semi-infinite fractional programming problems.   In the current interdisciplinary supercomputer-oriented research envi...

  1. On a fractional difference operator

    Directory of Open Access Journals (Sweden)

    P. Baliarsingh

    2016-06-01

    Full Text Available In the present article, a set of new difference sequence spaces of fractional order has been introduced and subsequently, an application of these spaces, the notion of the derivatives and the integrals of a function to the case of non-integer order have been generalized. Certain results involving the unusual and non-uniform behavior of the corresponding difference operator have been investigated and also been verified by using some counter examples. We also verify these unusual and non-uniform behaviors by studying the geometry of fractional calculus.

  2. Ca isotopic fractionation patterns in forest ecosystems

    Science.gov (United States)

    Kurtz, A. C.; Takagi, K.

    2012-12-01

    Calcium stable isotope ratios are an emerging tracer of the biogeochemical cycle of Ca that are just beginning to see significant application to forest ecosystems. The primary source of isotopic fractionation in these systems is discrimination against light Ca during uptake by plant roots. Cycling of vegetation-fractionated Ca establishes isotopically distinct Ca pools within a forest ecosystem. In some systems, the shallow soil exchangeable Ca pool is isotopically heavy relative to Ca inputs. This has been explained by preferential removal of light Ca from the soil. In other systems, the soil exchange pool is isotopically light relative to inputs, which is explained by recycling of plant-fractionated light Ca back into soil. Thus vegetation uptake of light Ca has been called on to account for both isotopically heavy and light Ca in the shallow soil exchange pools. We interpret patterns in ecosystem δ44Ca with the aid of a simple box model of the forest Ca cycle. We suggest that the δ44Ca of exchangeable Ca in the shallow soil pool primarily reflects the relative magnitude of three key fluxes in a forest Ca cycle, 1) the flux of external Ca into the system via weathering or atmospheric deposition, 2) the uptake flux of Ca from soils into the vegetation pool, and 3) the return flux of Ca to shallow soils via remineralization of leaf litter. Two observations that emerge from our model may aid in the application of Ca isotopes to provide insight into the forest Ca cycle. First, regardless of the magnitude of both vegetation Ca uptake and isotopic fractionation, the δ44Ca of the soil exchange pool will equal the input δ44Ca unless the plant uptake and remineralization fluxes are out of balance. A second observation is that the degree to which the shallow soil exchange pool δ44Ca can differ from the input ratio is controlled by the relative rates of biological uptake and external Ca input. Significant differences between soil exchange and input δ44Ca are seen only

  3. On a Fractional Binomial Process

    Science.gov (United States)

    Cahoy, Dexter O.; Polito, Federico

    2012-02-01

    The classical binomial process has been studied by Jakeman (J. Phys. A 23:2815-2825, 1990) (and the references therein) and has been used to characterize a series of radiation states in quantum optics. In particular, he studied a classical birth-death process where the chance of birth is proportional to the difference between a larger fixed number and the number of individuals present. It is shown that at large times, an equilibrium is reached which follows a binomial process. In this paper, the classical binomial process is generalized using the techniques of fractional calculus and is called the fractional binomial process. The fractional binomial process is shown to preserve the binomial limit at large times while expanding the class of models that include non-binomial fluctuations (non-Markovian) at regular and small times. As a direct consequence, the generality of the fractional binomial model makes the proposed model more desirable than its classical counterpart in describing real physical processes. More statistical properties are also derived.

  4. Riesz potential versus fractional Laplacian

    KAUST Repository

    Ortigueira, Manuel Duarte

    2014-09-01

    This paper starts by introducing the Grünwald-Letnikov derivative, the Riesz potential and the problem of generalizing the Laplacian. Based on these ideas, the generalizations of the Laplacian for 1D and 2D cases are studied. It is presented as a fractional version of the Cauchy-Riemann conditions and, finally, it is discussed with the n-dimensional Laplacian.

  5. A fast fractional difference algorithm

    DEFF Research Database (Denmark)

    Jensen, Andreas Noack; Nielsen, Morten Ørregaard

    2014-01-01

    We provide a fast algorithm for calculating the fractional difference of a time series. In standard implementations, the calculation speed (number of arithmetic operations) is of order T 2, where T is the length of the time series. Our algorithm allows calculation speed of order T log...

  6. A Fast Fractional Difference Algorithm

    DEFF Research Database (Denmark)

    Jensen, Andreas Noack; Nielsen, Morten Ørregaard

    We provide a fast algorithm for calculating the fractional difference of a time series. In standard implementations, the calculation speed (number of arithmetic operations) is of order T 2, where T is the length of the time series. Our algorithm allows calculation speed of order T log...

  7. Geodesic continued fractions and LLL

    NARCIS (Netherlands)

    Beukers, F

    2014-01-01

    We discuss a proposal for a continued fraction-like algorithm to determine simultaneous rational approximations to dd real numbers α1,…,αdα1,…,αd. It combines an algorithm of Hermite and Lagarias with ideas from LLL-reduction. We dynamically LLL-reduce a quadratic form with parameter tt as t↓0t↓0.

  8. A graph with fractional revival

    Science.gov (United States)

    Bernard, Pierre-Antoine; Chan, Ada; Loranger, Érika; Tamon, Christino; Vinet, Luc

    2018-02-01

    An example of a graph that admits balanced fractional revival between antipodes is presented. It is obtained by establishing the correspondence between the quantum walk on a hypercube where the opposite vertices across the diagonals of each face are connected and, the coherent transport of single excitations in the extension of the Krawtchouk spin chain with next-to-nearest neighbour interactions.

  9. Riesz potential versus fractional Laplacian

    KAUST Repository

    Ortigueira, Manuel Duarte; Laleg-Kirati, Taous-Meriem; Machado, José Antó nio Tenreiro

    2014-01-01

    This paper starts by introducing the Grünwald-Letnikov derivative, the Riesz potential and the problem of generalizing the Laplacian. Based on these ideas, the generalizations of the Laplacian for 1D and 2D cases are studied. It is presented as a fractional version of the Cauchy-Riemann conditions and, finally, it is discussed with the n-dimensional Laplacian.

  10. What next in fractionated radiotherapy

    International Nuclear Information System (INIS)

    Fowler, J.F.

    1984-01-01

    Trends in models for predicting the total dose required to produce tolerable normal-tissue injury can be seen by the progression from the ''cube root law'', through Strandqvist's slope of 0.22, to NSD, TDF and CRE which have separate time and fraction number exponents, to even better approximations now available. The dose-response formulae that can be used to define the effect of fraction size (and number) include (1) the linear quadratic (LQ) model (2) the two-component (TC) multi-target model and (3) repair-misrepair models. The LQ model offers considerable convenience, requires only two parameters to be determined, and emphasizes the difference between late and early normal-tissue dependence on dose per fraction first shown by exponents greater than the NSD slope of 0.24. Exponents of overall time, e.g. Tsup(0.11), yield the wrong shape of time curve, suggesting that most proliferating occurs early, although it really occurs after a delay depending on the turnover time of the tissue. Improved clinical results are being sought by hyperfractionation, accelerated fractionation, or continuous low dose rate irradiation as in interstitial implants. (U.K.)

  11. Fractional Laplace Transforms - A Perspective

    Directory of Open Access Journals (Sweden)

    Rudolf A. Treumann

    2014-06-01

    Full Text Available A new form of the Laplace transform is reviewed as a paradigm for an entire class of fractional functional transforms. Various of its properties are discussed. Such transformations should be useful in application to differential/integral equations or problems in non-extensive statistical mechanics.

  12. Pythagorean Approximations and Continued Fractions

    Science.gov (United States)

    Peralta, Javier

    2008-01-01

    In this article, we will show that the Pythagorean approximations of [the square root of] 2 coincide with those achieved in the 16th century by means of continued fractions. Assuming this fact and the known relation that connects the Fibonacci sequence with the golden section, we shall establish a procedure to obtain sequences of rational numbers…

  13. Fractional Processes and Fractional-Order Signal Processing Techniques and Applications

    CERN Document Server

    Sheng, Hu; Qiu, TianShuang

    2012-01-01

    Fractional processes are widely found in science, technology and engineering systems. In Fractional Processes and Fractional-order Signal Processing, some complex random signals, characterized by the presence of a heavy-tailed distribution or non-negligible dependence between distant observations (local and long memory), are introduced and examined from the ‘fractional’ perspective using simulation, fractional-order modeling and filtering and realization of fractional-order systems. These fractional-order signal processing (FOSP) techniques are based on fractional calculus, the fractional Fourier transform and fractional lower-order moments. Fractional Processes and Fractional-order Signal Processing: • presents fractional processes of fixed, variable and distributed order studied as the output of fractional-order differential systems; • introduces FOSP techniques and the fractional signals and fractional systems point of view; • details real-world-application examples of FOSP techniques to demonstr...

  14. Monodispersed Carbon-Coated Cubic NiP2 Nanoparticles Anchored on Carbon Nanotubes as Ultra-Long-Life Anodes for Reversible Lithium Storage.

    Science.gov (United States)

    Lou, Peili; Cui, Zhonghui; Jia, Zhiqing; Sun, Jiyang; Tan, Yingbin; Guo, Xiangxin

    2017-04-25

    In search of new electrode materials for lithium-ion batteries, metal phosphides that exhibit desirable properties such as high theoretical capacity, moderate discharge plateau, and relatively low polarization recently have attracted a great deal of attention as anode materials. However, the large volume changes and thus resulting collapse of electrode structure during long-term cycling are still challenges for metal-phosphide-based anodes. Here we report an electrode design strategy to solve these problems. The key to this strategy is to confine the electroactive nanoparticles into flexible conductive hosts (like carbon materials) and meanwhile maintain a monodispersed nature of the electroactive particles within the hosts. Monodispersed carbon-coated cubic NiP 2 nanoparticles anchored on carbon nanotubes (NiP 2 @C-CNTs) as a proof-of-concept were designed and synthesized. Excellent cyclability (more than 1000 cycles) and capacity retention (high capacities of 816 mAh g -1 after 1200 cycles at 1300 mA g -1 and 654.5 mAh g -1 after 1500 cycles at 5000 mA g -1 ) are characterized, which is among the best performance of the NiP 2 anodes and even most of the phosphide-based anodes reported so far. The impressive performance is attributed to the superior structure stability and the enhanced reaction kinetics incurred by our design. Furthermore, a full cell consisting of a NiP 2 @C-CNTs anode and a LiFePO 4 cathode is investigated. It delivers an average discharge capacity of 827 mAh g -1 based on the mass of the NiP 2 anode and exhibits a capacity retention of 80.7% over 200 cycles, with an average output of ∼2.32 V. As a proof-of-concept, these results demonstrate the effectiveness of our strategy on improving the electrode performance. We believe that this strategy for construction of high-performance anodes can be extended to other phase-transformation-type materials, which suffer a large volume change upon lithium insertion/extraction.

  15. Modeling discrete and continuous entities with fractions and decimals.

    Science.gov (United States)

    Rapp, Monica; Bassok, Miriam; DeWolf, Melissa; Holyoak, Keith J

    2015-03-01

    When people use mathematics to model real-life situations, their use of mathematical expressions is often mediated by semantic alignment (Bassok, Chase, & Martin, 1998): The entities in a problem situation evoke semantic relations (e.g., tulips and vases evoke the functionally asymmetric "contain" relation), which people align with analogous mathematical relations (e.g., the noncommutative division operation, tulips/vases). Here we investigate the possibility that semantic alignment is also involved in the comprehension and use of rational numbers (fractions and decimals). A textbook analysis and results from two experiments revealed that both mathematic educators and college students tend to align the discreteness versus continuity of the entities in word problems (e.g., marbles vs. distance) with distinct symbolic representations of rational numbers--fractions versus decimals, respectively. In addition, fractions and decimals tend to be used with nonmetric units and metric units, respectively. We discuss the importance of the ontological distinction between continuous and discrete entities to mathematical cognition, the role of symbolic notations, and possible implications of our findings for the teaching of rational numbers. PsycINFO Database Record (c) 2015 APA, all rights reserved.

  16. Fractional governing equations of transient groundwater flow in confined aquifers with multi-fractional dimensions in fractional time

    Directory of Open Access Journals (Sweden)

    M. L. Kavvas

    2017-10-01

    Full Text Available Using fractional calculus, a dimensionally consistent governing equation of transient, saturated groundwater flow in fractional time in a multi-fractional confined aquifer is developed. First, a dimensionally consistent continuity equation for transient saturated groundwater flow in fractional time and in a multi-fractional, multidimensional confined aquifer is developed. For the equation of water flux within a multi-fractional multidimensional confined aquifer, a dimensionally consistent equation is also developed. The governing equation of transient saturated groundwater flow in a multi-fractional, multidimensional confined aquifer in fractional time is then obtained by combining the fractional continuity and water flux equations. To illustrate the capability of the proposed governing equation of groundwater flow in a confined aquifer, a numerical application of the fractional governing equation to a confined aquifer groundwater flow problem was also performed.

  17. Soil tension mediates isotope fractionation during soil water evaporation

    Science.gov (United States)

    Gaj, Marcel; McDonnell, Jeffrey

    2017-04-01

    Isotope tracing of the water cycle is increasing in its use and usefulness. Many new studies are extracting soil waters and relating these to streamflow, groundwater recharge and plant transpiration. Nevertheless, unlike isotope fractionation factors from open water bodies, soil water fractionation factors are poorly understood and until now, only empirically derived. In contrast to open water evaporation where temperature, humidity and vapor pressure gradient define fractionation (as codified in the well-known Craig and Gordon model), soil water evaporation includes additionally, fractionation by matrix effects. There is yet no physical explanation of kinetic and equilibrium fraction from soil water within the soil profile. Here we present a simple laboratory experiment with four admixtures of soil grain size (from sand to silt to clay). Oven-dried samples were spiked with water of known isotopic composition at different soil water contents. Soils were then stored in sealed bags and the headspace filled with dry air and allowed to equilibrate for 24hours. Isotopic analysis of the headspace vapor was done with a Los Gatos Inc. water vapor isotope analyzer. Soil water potential of subsamples were measured with a water potential meter. We show for the first time that soil tension controls isotope fractionation in the resident soil water. Below a Pf 3.5 the δ-values of 18O and 2H of the headspace vapor is more positive and increases with increasing soil water potential. Surprisingly, we find that the relationship between soil tension and equilibrium fractionation is independent of soil type. However, δ-values of each soil type plot along a distinct evaporation line. These results indicate that equilibrium fractionation is affected by soil tension in addition to temperature. Therefore, at high soil water tension (under dry conditions) equilibrium fractionation is not consistent with current empirical formulations that ignore these effects. These findings may have

  18. Distinctiveness of Saudi Arabian EFL Learners

    Directory of Open Access Journals (Sweden)

    Manssour Habbash

    2016-04-01

    Full Text Available In view of the increasing concern among English language teachers dealing with students from Saudi Arabia, as it manifests in TESOL community discussions, about the uniqueness of Saudi Arabian EFL learners, this paper attempts to document the outcome of a study of their distinctiveness from the perspective of expatriate teachers working for PYPs (Preparatory Year Programs in Saudi Arabia. This study examines the distinctiveness with regard to the learning attitudes of Saudi students that are often cultivated by the culture and academic environment in their homeland. Employing an emic approach for collecting the required data an analysis was carried out in light of the other studies on ‘education’ in Saudi Arabia that have particular reference to the factors that can positively influence student motivation, student success and the academic environment. The findings were used in constructing the rationale behind such distinctiveness. Assuming that the outcome of the discussion on the findings of this exploration can be helpful for teachers in adapting their teaching methodology and improving their teacher efficacy in dealing with students both from the kingdom and in the kingdom, some recommendations are made. Keywords: China Distinctiveness, Saudi Arabian University context, Expatriate teachers’ perspective, Distinctiveness Theory

  19. Ultra small angle neutron scattering : a tool to study packing of relatively monodisperse small polymer spheres and their binary mixtures

    International Nuclear Information System (INIS)

    Reynolds, Philip A.; McGillivray, Duncan J.; White, John W.; Jackson, Andrew J.; University of Maryland, College Paerk, Maryland, USA

    2009-01-01

    Full text: We measured ultra small angle neutron scattering (USANS) from polymethylmethacrylate spheres tamped down in air. Two slightly polydisperse pure sphere sizes (1.5/-lm and 7.5/-lm diameter) and five mixtures of these were used. All were loose packed (packing fractions 0.3 to 0.6) with nongravitational forces (e.g., friction) important, preventing close packing. The USANS data is rich in information on powder packing. A modified Percus-Yevick fluid model was used to parametrise the data - adequately but not well. The modifications required introduction of small voids, less than the sphere size, and a parameter reflecting substantial deviation from the Percus-Yevick prediction of the sphere-sphere correlation function. The mixed samples fitted less well, and two further modifying factors were necessary. These were local inhomogeneities, where the concentration of same-size spheres, both large and small, deviated from the mean packing, and a factor accounting for the presence within these 'clusters' of self avoidance of the large spheres (that is large spheres coated with more small spheres than Percus-Yevick would predict). The overall deviations from the hardsphere Percus-Yevick model that we find here suggests fluid models of loose packed powders are unlikely to be successful, but lay the groundwork for future theoretical and computational work.

  20. Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(ε-caprolactone) micelles and their antimicrobial application

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Chunhua [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zhang, Huan [State Key Laboratory of Bioreactor Engineering, New World Biotechnology Institute, East China University of Science and Technology, Shanghai 200237 (China); Lang, Meidong, E-mail: mdlang@ecust.edu.cn [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China)

    2014-05-01

    Graphical abstract: - Highlights: • Chemical modification of chitosan were conducted after phthaloyl protection of amino groups. • Silver nanoparticles were prepared in the presence of chitosan-based copolymer micelles. • The optimal time scale and weight ratios of silver to micelles were monitored by UV–vis spectrometer. - Abstract: Amphiphilic chitosan-graft-poly(ε-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by {sup 1}H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV–vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria.

  1. Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(ε-caprolactone) micelles and their antimicrobial application

    International Nuclear Information System (INIS)

    Gu, Chunhua; Zhang, Huan; Lang, Meidong

    2014-01-01

    Graphical abstract: - Highlights: • Chemical modification of chitosan were conducted after phthaloyl protection of amino groups. • Silver nanoparticles were prepared in the presence of chitosan-based copolymer micelles. • The optimal time scale and weight ratios of silver to micelles were monitored by UV–vis spectrometer. - Abstract: Amphiphilic chitosan-graft-poly(ε-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by 1 H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV–vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria

  2. Generalized time fractional IHCP with Caputo fractional derivatives

    International Nuclear Information System (INIS)

    Murio, D A; MejIa, C E

    2008-01-01

    The numerical solution of the generalized time fractional inverse heat conduction problem (GTFIHCP) on a finite slab is investigated in the presence of measured (noisy) data when the time fractional derivative is interpreted in the sense of Caputo. The GTFIHCP involves the simultaneous identification of the heat flux and temperature transient functions at one of the boundaries of the finite slab together with the initial condition of the original direct problem from noisy Cauchy data at a discrete set of points on the opposite (active) boundary. A finite difference space marching scheme with adaptive regularization, using trigonometric mollification techniques and generalized cross validation is introduced. Error estimates for the numerical solution of the mollified problem and numerical examples are provided.

  3. Some comparison of two fractional oscillators

    International Nuclear Information System (INIS)

    Kang Yonggang; Zhang Xiu'e

    2010-01-01

    The other form of fractional oscillator equation comparing to the widely discussed one is ushered in. The properties of vibration of two fractional oscillators are discussed under the influence of different initial conditions. The interpretation of the characteristics of the fractional oscillators using different method is illustrated. Based on two fractional oscillator equations, two linked bodies and the continuous system are studied.

  4. 9 CFR 113.7 - Multiple fractions.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Multiple fractions. 113.7 Section 113... § 113.7 Multiple fractions. (a) When a biological product contains more than one immunogenic fraction, the completed product shall be evaluated by tests applicable to each fraction. (b) When similar...

  5. A fractional Dirac equation and its solution

    International Nuclear Information System (INIS)

    Muslih, Sami I; Agrawal, Om P; Baleanu, Dumitru

    2010-01-01

    This paper presents a fractional Dirac equation and its solution. The fractional Dirac equation may be obtained using a fractional variational principle and a fractional Klein-Gordon equation; both methods are considered here. We extend the variational formulations for fractional discrete systems to fractional field systems defined in terms of Caputo derivatives. By applying the variational principle to a fractional action S, we obtain the fractional Euler-Lagrange equations of motion. We present a Lagrangian and a Hamiltonian for the fractional Dirac equation of order α. We also use a fractional Klein-Gordon equation to obtain the fractional Dirac equation which is the same as that obtained using the fractional variational principle. Eigensolutions of this equation are presented which follow the same approach as that for the solution of the standard Dirac equation. We also provide expressions for the path integral quantization for the fractional Dirac field which, in the limit α → 1, approaches to the path integral for the regular Dirac field. It is hoped that the fractional Dirac equation and the path integral quantization of the fractional field will allow further development of fractional relativistic quantum mechanics.

  6. On the fractional calculus of Besicovitch function

    International Nuclear Information System (INIS)

    Liang Yongshun

    2009-01-01

    Relationship between fractional calculus and fractal functions has been explored. Based on prior investigations dealing with certain fractal functions, fractal dimensions including Hausdorff dimension, Box dimension, K-dimension and Packing dimension is shown to be a linear function of order of fractional calculus. Both Riemann-Liouville fractional calculus and Weyl-Marchaud fractional derivative of Besicovitch function have been discussed.

  7. 12 CFR 5.67 - Fractional shares.

    Science.gov (United States)

    2010-01-01

    ... connection with fractional shares, a national bank issuing additional stock by stock dividend, upon... fair price upon the fraction not being issued through its sale, or the purchase of the additional... stock; (c) Remit the cash equivalent of the fraction not being issued to those to whom fractional shares...

  8. On Hobbes’s distinction of accidents

    Directory of Open Access Journals (Sweden)

    Lupoli Agostino

    2012-06-01

    Full Text Available An interpolation introduced by K. Schuhmann in his critical edition of "De corpore" (chap. VI, § 13 diametrically overturns the meaning of Hobbes’s doctrine of distinction of accidents in comparison with all previous editions. The article focuses on the complexity of this crucial juncture in "De corpore" argument on which depends the interpretation of Hobbes’s whole conception of science. It discusses the reasons pro and contra Schuhmann’s interpolation and concludes against it, because it is not compatible with the rationale underlying the complex architecture of "De corpore", which involves a symmetry between the ‘logical’ distinction of accidents and the ‘metaphysical’ distinction of phantasms.

  9. What makes health promotion research distinct?

    Science.gov (United States)

    Woodall, James; Warwick-Booth, Louise; South, Jane; Cross, Ruth

    2018-02-01

    There have been concerns about the decline of health promotion as a practice and discipline and, alongside this, calls for a clearer articulation of health promotion research and what, if anything, makes it distinct. This discussion paper, based on a review of the literature, the authors' own experiences in the field, and a workshop delivered by two of the authors at the 8th Nordic Health Promotion Conference, seeks to state the reasons why health promotion research is distinctive. While by no means exhaustive, the paper suggests four distinctive features. The paper hopes to be a catalyst to enable health promotion researchers to be explicit in their practice and to begin the process of developing an agreed set of research principles.

  10. Intergroup Leadership Across Distinct Subgroups and Identities.

    Science.gov (United States)

    Rast, David E; Hogg, Michael A; van Knippenberg, Daan

    2018-03-01

    Resolving intergroup conflict is a significant and often arduous leadership challenge, yet existing theory and research rarely, if ever, discuss or examine this situation. Leaders confront a significant challenge when they provide leadership across deep divisions between distinct subgroups defined by self-contained identities-The challenge is to avoid provoking subgroup identity distinctiveness threat. Drawing on intergroup leadership theory, three studies were conducted to test the core hypothesis that, where identity threat exists, leaders promoting an intergroup relational identity will be better evaluated and are more effective than leaders promoting a collective identity; in the absence of threat, leaders promoting a collective identity will prevail. Studies 1 and 2 ( N = 170; N = 120) supported this general proposition. Study 3 ( N = 136) extended these findings, showing that leaders promoting an intergroup relational identity, but not a collective identity, improved intergroup attitudes when participants experienced an identity distinctiveness threat.

  11. Distinctive Dynamic Capabilities for New Business Creation

    DEFF Research Database (Denmark)

    Rosenø, Axel; Enkel, Ellen; Mezger, Florian

    2013-01-01

    This study examines the distinctive dynamic capabilities for new business creation in established companies. We argue that these are very different from those for managing incremental innovation within a company's core business. We also propose that such capabilities are needed in both slow...... and fast-paced industries, and that similarities exist across industries. Hence, the study contributes to dynamic capabilities literature by: 1) identifying the distinctive dynamic capabilities for new business creation; 2) shifting focus away from dynamic capabilities in environments characterised by high...... clock-speed and uncertainty towards considering dynamic capabilities for the purpose of developing new businesses, which also implies a high degree of uncertainty. Based on interviews with 33 companies, we identify distinctive dynamic capabilities for new business creation, find that dynamic...

  12. Fractional vector calculus and fluid mechanics

    Science.gov (United States)

    Lazopoulos, Konstantinos A.; Lazopoulos, Anastasios K.

    2017-04-01

    Basic fluid mechanics equations are studied and revised under the prism of fractional continuum mechanics (FCM), a very promising research field that satisfies both experimental and theoretical demands. The geometry of the fractional differential has been clarified corrected and the geometry of the fractional tangent spaces of a manifold has been studied in Lazopoulos and Lazopoulos (Lazopoulos KA, Lazopoulos AK. Progr. Fract. Differ. Appl. 2016, 2, 85-104), providing the bases of the missing fractional differential geometry. Therefore, a lot can be contributed to fractional hydrodynamics: the basic fractional fluid equations (Navier Stokes, Euler and Bernoulli) are derived and fractional Darcy's flow in porous media is studied.

  13. FRACTIONATION AND CHARACTERISATION OF TECHNICAL AMMONIUM LIGNOSULPHONATE

    Directory of Open Access Journals (Sweden)

    Cheryl Ann Leger

    2010-08-01

    Full Text Available It is difficult to use lignin in any analytical methodology without reducing its considerable polydispersity by fractionation. An ammonium lignosulphonate sample was fractionated using a method of partial solubility in solutions of isopropanol increasingly diluted with distilled water, effectively fractionating by polarity. Selected fractions were characterised by gravimetric determination of the fractions, and determination of acid insoluble lignin, soluble lignin, and carbohydrate contents. Acid-insoluble lignin content was very low, and soluble lignin provided the majority of the lignin content, as should be expected from sulphonated lignin. Carbohydrate contents were also fairly low, the highest percentage at 14.5 being in Fraction 2, with the bulk lignin and Fraction 3 having 6.5% and 3.2%, respectively. Differences in the composition of each fraction support the efficacy of the fractionation process and permitted selection of fractions for use in subsequent studies.

  14. Generalized Arcsine Laws for Fractional Brownian Motion.

    Science.gov (United States)

    Sadhu, Tridib; Delorme, Mathieu; Wiese, Kay Jörg

    2018-01-26

    The three arcsine laws for Brownian motion are a cornerstone of extreme-value statistics. For a Brownian B_{t} starting from the origin, and evolving during time T, one considers the following three observables: (i) the duration t_{+} the process is positive, (ii) the time t_{last} the process last visits the origin, and (iii) the time t_{max} when it achieves its maximum (or minimum). All three observables have the same cumulative probability distribution expressed as an arcsine function, thus the name arcsine laws. We show how these laws change for fractional Brownian motion X_{t}, a non-Markovian Gaussian process indexed by the Hurst exponent H. It generalizes standard Brownian motion (i.e., H=1/2). We obtain the three probabilities using a perturbative expansion in ϵ=H-1/2. While all three probabilities are different, this distinction can only be made at second order in ϵ. Our results are confirmed to high precision by extensive numerical simulations.

  15. Fractional hydrodynamic equations for fractal media

    International Nuclear Information System (INIS)

    Tarasov, Vasily E.

    2005-01-01

    We use the fractional integrals in order to describe dynamical processes in the fractal medium. We consider the 'fractional' continuous medium model for the fractal media and derive the fractional generalization of the equations of balance of mass density, momentum density, and internal energy. The fractional generalization of Navier-Stokes and Euler equations are considered. We derive the equilibrium equation for fractal media. The sound waves in the continuous medium model for fractional media are considered

  16. Geometrical explanation of the fractional complex transform and derivative chain rule for fractional calculus

    International Nuclear Information System (INIS)

    He, Ji-Huan; Elagan, S.K.; Li, Z.B.

    2012-01-01

    The fractional complex transform is suggested to convert a fractional differential equation with Jumarie's modification of Riemann–Liouville derivative into its classical differential partner. Understanding the fractional complex transform and the chain rule for fractional calculus are elucidated geometrically. -- Highlights: ► The chain rule for fractional calculus is invalid, a counter example is given. ► The fractional complex transform is explained geometrically. ► Fractional equations can be converted into differential equations.

  17. Tunable multicolor and enhanced red emission of monodisperse CaF2:Yb3+/Ho3+ microspheres via Mn2+ doping

    Science.gov (United States)

    Wang, Rui; Yuan, Maohui; Zhang, Chaofan; Wang, Hongyan; Xu, Xiaojun

    2018-05-01

    Transition metal ions (e.g. Mn2+) and lanthanide co-doped upconversion (UC) materials have attracted wide attention in recent years due to their promising application in multicolor display. Here, we report the hydrothermal synthesis and characterization of Mn2+ doped monodisperse CaF2:Yb3+/Ho3+ microspheres. The results of X-ray diffraction (XRD) revealed that Mn2+ doping does not change the cubic phase of CaF2 material but will lead to diffraction peaks shifting slightly towards higher angle due to the substitution of larger Ca2+ by the relatively smaller Mn2+. Under the excitation of 980 nm continuous wave (CW) laser, these microspheres exhibit green-yellow-red tuning colors and remarkable enhancement of both red to green ratio (R/G) and red to blue ratio (R/B) when increasing Mn2+ concentration from 0 to 30 mol%. The energy migration process between Ho3+ and Mn2+ was proposed and supported by time-decay and power dependence measurements of Ho3+ UC emission. These upconversion materials may have potential applications in optical devices, color display, nanoscale lasers and biomedical imaging.

  18. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

    Science.gov (United States)

    Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

    2016-01-13

    High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.

  19. Dry aerosol of monodisperse millimicrospheres for ventilation imaging: Production, delivery system, and clinical results in comparison with /sup 81m/Kr and /sup 127/Xe

    Energy Technology Data Exchange (ETDEWEB)

    Koehn, H; Mostbeck, A; Klech, H; Kummer, F; Angelberger, P; Strigl, A; Zolle, I

    1985-05-01

    The production of monodisperse human albumin millimicrospheres (diameter 1 ..mu..m) and labeling with /sup 99m/Tc is described. A system constructed to nebulize and deliver a dry aerosol yielded a lung delivery efficiency of approximately 25%. In 48 patients without and with varying degrees of chronic obstructive lung disease, quantitative comparison with /sup 81m/Kr (penetration index, regional distribution of activity in the lungs) demonstrated similar penetration of the particles to the lung periphery (r = 0.89 and r = 0.94, respectively). Qualitative comparison with /sup 81m/Kr or /sup 127/Xe showed complete or a high degree of diagnostic agreement in all but one patient. Semiquantitative scoring of hot spots as a substrate of local turbulent airflow showed a close inverse correlation (r = -0.82) with the forced expiratory volume in 1 s (FEV 1.0%), thus providing additional information about the severity of the airway obstruction. In 24 patients with suspected pulmonary embolism, complete agreement between aerosol and /sup 81m/Kr images was found in all patients studied. For same-day ventilation/perfusion studies, labeling of the millimicrospheres with /sup 111/In yielded images of comparable quality to those obtained with the /sup 99m/Tc-labeled aerosol.

  20. Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rongzheng; Liu, Malin, E-mail: liumalin@tsinghua.edu.cn; Chang, Jiaxing [Tsinghua University, Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology (China)

    2017-02-15

    A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H{sub 2} system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

  1. Monodisperse porous LiFePO4/C microspheres derived by microwave-assisted hydrothermal process combined with carbothermal reduction for high power lithium-ion batteries

    Science.gov (United States)

    Chen, Rongrong; Wu, Yixiong; Kong, Xiang Yang

    2014-07-01

    A microwave-assisted hydrothermal approach combined with carbothermal reduction has been developed to synthesize monodisperse porous LiFePO4/C microspheres, which possess the diameter range of 1.0-1.5 μm, high tap density of ∼1.3 g cm-3, and mesoporous characteristic with Brunauer-Emmett-Teller (BET) surface area of 30.6 m2 g-1. The obtained microspheres show meatball-like morphology aggregated by the carbon-coated LiFePO4 nanoparticles. The electrochemical impedance spectra (EIS) results indicate that carbon coating can effectively enhance both of the electronic and ionic conductivities for LiFePO4/C microspheres. The Li-ion diffusion coefficient of the LiFePO4/C microspheres calculated from the cyclic voltammetry (CV) curves is ∼6.25 × 10-9 cm2 s-1. The electrochemical performance can achieve about 100 and 90 mAh g-1 at 5C and 10C charge/discharge rates, respectively. As cathode material, the as-prepared LiFePO4/C microspheres show excellent rate capability and cycle stability, promising for high power lithium-ion batteries.

  2. Dispersed-nanoparticle loading synthesis for monodisperse Au-titania composite particles and their crystallization for highly active UV and visible photocatalysts.

    Science.gov (United States)

    Sakamoto, Takeshi; Nagao, Daisuke; Noba, Masahiro; Ishii, Haruyuki; Konno, Mikio

    2014-06-24

    Submicrometer-sized amorphous titania spheres incorporating Au nanoparticles (NPs) were prepared in a one-pot synthesis consisting of a sol-gel reaction of titanium(IV) isopropoxide in the presence of chloroauric acid and a successive reduction with sodium borohydride in a mixed solvent of ethanol/acetonitrile. The synthesis was allowed to prepare monodisperse titania spheres that homogeneously incorporated Au NPs with sizes of ca. 7 nm. The Au NP-loaded titania spheres underwent different crystallization processes, including 500 °C calcination in air, high-temperature hydrothermal treatment (HHT), and/or low-temperature hydrothermal treatment (LHT). Photocatalytic experiments were conducted with the Au NP-loaded crystalline titania spheres under irradiation of UV and visible light. A combined process of LHT at 80 °C followed by calcination at 500 °C could effectively crystallize titania spheres maintaining the dispersion state of Au NPs, which led to photocatalytic activity higher than that of commercial P25 under UV irradiation. Under visible light irradiation, the Au NP-titania spheres prepared with a crystallization process of LHT at 80 °C for 6 h showed photocatalytic activity much higher than a commercial product of visible light photocatalyst. Structure analysis of the visible light photocatalysts indicates the importance of prevention of the Au NPs aggregation in the crystallization processes for enhancement of photocatalytic activity.

  3. Monodisperse MnO2@NiCo2O4 core/shell nanospheres with highly opened structures as electrode materials for good-performance supercapacitors

    Science.gov (United States)

    Zhou, You; Ma, Li; Gan, Mengyu; Ye, Menghan; Li, Xiurong; Zhai, Yanfang; Yan, Fabing; Cao, Feifei

    2018-06-01

    The monodisperse MnO2@NiCo2O4 core/shell nanospheres for good-performance supercapacitors are designed and synthesized by a two-step solution-based method and a simple post annealing process. In the composite, both MnO2 (the "core") and NiCo2O4 (the "shell") are formed by the accumulation of nanoflakes. Thus, nearly all the core/shell nanoflakes are highly opened and accessible to electrolyte, making them give full play to the Faradaic reaction. Our results demonstrate that the composite electrode exhibits desirable pseudocapacitive behaviors with higher specific capacitance (1127.27 F g-1 at a current density of 1 A g-1), better rate capability (81.0% from 1 to 16 A g-1) and superior cycling stability (actually 126.8% capacitance retention after 1000 cycles and only 3.7% loss after 10,000 cycles at 10 A g-1) in 3 M KOH aqueous solution. Moreover, it offers the excellent specific energy density of 26.6 Wh kg-1 at specific power density of 800 W kg-1. The present MnO2@NiCo2O4 core/shell nanospheres with remarkable electrochemical properties are considered as potential electrode materials for the next generation supercapacitors.

  4. Inhibition of Neuroblastoma cancer cells viability by ferromagnetic Mn doped CeO_2 monodisperse nanoparticles mediated through reactive oxygen species

    International Nuclear Information System (INIS)

    Abbas, Fazal; Jan, Tariq; Iqbal, Javed; Haider Naqvi, M. Sajjad; Ahmad, Ishaq

    2016-01-01

    Here we report the Mn doping induced effects on structural, Raman, optical, magnetic and anticancer properties of CeO_2 nanoparticles prepared via soft chemical route. Structural and microstructural results infer that the synthesized nanoparticles have single phase cubic fluorite structure of CeO_2 and that Mn doping results in enhancement of the structural defects. Scanning electron microscopy results reveal the formation of monodisperse nanoparticles having average particle size ranging from 30 to 41 nm. The optical absorbance spectroscopy analysis discloses the band gap energy tailoring of CeO_2 nanoparticles via Mn doping. Room temperature ferromagnetism (RTFM) has been found in both as-prepared and Mn doped CeO_2 nanoparticles. This RTFM of the synthesized nanoparticles have been attributed to the Mn ions and surface defects such as oxygen vacancies. Finally, the influence of Mn dopant on the cell viability and reactive oxygen species (ROS) generation levels of CeO_2 nanoparticles in the presence of healthy and cancerous cells have been studied. It has been observed that the differential cytotoxicity of the synthesized nanoparticles is strongly correlated with level of ROS generation. - Highlights: • Mn doped CeO_2 nanoparticles with cubic fluorite structure were synthesized. • Mn dopant significantly tailored the band gap of CeO_2 nanoparticles. • The synthesized nanoparticles exhibited room temperature ferromagnetic behavior. • The cytotoxicity of these nanoparticles was reported for the first time. • The synthesized nanoparticles exhibited differential cytotoxicity.

  5. Monodisperse, molecularly imprinted polymers for creatinine by modified precipitation polymerization and their applications to creatinine assays for human serum and urine.

    Science.gov (United States)

    Miura, Chitose; Funaya, Noriko; Matsunaga, Hisami; Haginaka, Jun

    2013-11-01

    Molecularly imprinted polymers (MIPs) for creatinine were prepared by modified precipitation polymerization using methacrylic acid as a functional monomer and divinylbenzene as a crosslinker. The prepared MIPs were monodispersed with a narrow particle size distribution. Binding experiments and Scatchard analyses revealed that two classes of binding sites, high- and low-affinity sites, were formed on the MIPs. The retention and molecular-recognition properties of the MIPs were evaluated by hydrophilic interaction chromatography using a mixture of ammonium acetate buffer and acetonitrile as a mobile phase. With an increase of acetonitrile content, the retention factor of creatinine was increased on the MIP. In addition to shape recognition, hydrophilic interactions seemed to enhance the recognition of creatinine on the MIP. The MIPs' molecular-recognition ability was specific for creatinine; the structurally related compounds such as hydantoin, 1-methylhydantoin, 2-pyrrolidone, N-hydroxysuccinimide and creatine were not recognized. Furthermore, the creatinine concentrations in human serum and urine were successfully determined by direct injection of the deproteinized serum and diluted urine samples onto the MIP. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Rapid synthesis of monodispersed highly porous spinel nickel cobaltite (NiCo{sub 2}O{sub 4}) electrode material for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Naveen, A. Nirmalesh, E-mail: nirmalesh.naveen@gmail.com; Selladurai, S. [Ionics Laboratory, Department of Physics, Anna University, Chennai-600025 (India)

    2015-06-24

    Monodispersed highly porous spinel nickel cobaltite electrode material was successfully synthesized in a short time using combustion technique. Single phase cubic nature of the spinel nickel cobaltite with average crystallite size of 24 nm was determined from X-ray diffraction study. Functional groups present in the compound were determined from FTIR study and it further confirms the spinel formation. FESEM images reveal the porous nature of the prepared material and uniform size distribution of the particles. Electrochemical evaluation was performed using Cyclic Voltammetry (CV) technique, Chronopotentiometry (CP) and Electrochemical Impedance Spectroscopy (EIS). Results reveal the typical pseudocapacitive behaviour of the material. Maximum capacitance of 754 F/g was calculated at the scan rate of 5 mV/s, high capacitance was due to the unique porous morphology of the electrode. Nyquist plot depicts the low resistance and good electrical conductivity of nickel cobaltite. It has been found that nickel cobaltite prepared by this typical method will be a potential electrode material for supercapcitor application.

  7. Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications.

    Science.gov (United States)

    Singh, Jay; Srivastava, M; Dutta, Joydeep; Dutta, P K

    2011-01-01

    In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Monodisperse SnO2 nanocrystals functionalized multiwalled carbon nanotubes for large rate and long lifespan anode materials in lithium ion batteries

    International Nuclear Information System (INIS)

    Song, Huawei; Li, Na; Cui, Hao; Wang, Chengxin

    2014-01-01

    A facile way towards high rate and long lifespan anode materials based on SnO 2 and commercial multiwalled carbon nanotubes (MWCNTs) is readily achieved through a combination of activation and hydrothermal treatment. The former endows the MWCNTs with abundant hydrophilic radicals, while the latter guarantees intimate connection between SnO 2 and MWCNTs; eventually, monodisperse SnO 2 nanocrystals ca. 3 nm are firmly anchored on the MWCNTs without agglomeration. When used for lithium ion batteries (LIBs) anodes, the hybrid composite exhibits excellent cycling capability with high reversible capacity about 700 mAh g −1 (based on total weight of the composite) for 150 cycles at 0.1 A g −1 superior to both components involved. Besides large rates of 5 A g −1 with recoverable initial reversible capacity, it also last for more than 1000 cycles with little capacity decay, outperforming most SnO 2 based carbon nanotubes composites (SnO 2 /CNTs) so far. Insights into the electrochemical processes reveal the hybrid composite exhibits enhanced redox capacitance and interfacial capacitance in comparison with SnO 2 nanocrystals which indicate the perfect interfaces and robust structure of the hybrid composite

  9. Large-scale synthesis of monodisperse SiC nanoparticles with adjustable size, stoichiometric ratio and properties by fluidized bed chemical vapor deposition

    International Nuclear Information System (INIS)

    Liu, Rongzheng; Liu, Malin; Chang, Jiaxing

    2017-01-01

    A facile fluidized bed chemical vapor deposition method was proposed for the synthesis of monodisperse SiC nanoparticles by using the single precursor of hexamethyldisilane (HMDS). SiC nanoparticles with average particle size from 10 to 200 nm were obtained by controlling the temperature and the gas ratio. An experimental chemical vapor deposition phase diagram of SiC in the HMDS-Ar-H_2 system was obtained and three regions of SiC-Si, SiC and SiC-C can be distinguished. The BET surface area and the photoluminescence properties of the SiC nanoparticles can be adjusted by changing the nanoparticle size. For the SiC nanospheres with free carbon, a novel hierarchical structure with 5 ~ 8 nm SiC nanoparticles embedded into the graphite matrix was obtained. The advantages of fluidized bed technology for the preparation of SiC nanoparticles were proposed based on the features of homogenous reaction zone, narrow temperature distribution, ultra-short reactant residence time and mass production.

  10. Microfluidic assembly of monodisperse multistage pH-responsive polymer/porous silicon composites for precisely controlled multi-drug delivery.

    Science.gov (United States)

    Liu, Dongfei; Zhang, Hongbo; Herranz-Blanco, Bárbara; Mäkilä, Ermei; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2014-05-28

    We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Continuous fractional distillation of petroleum

    Energy Technology Data Exchange (ETDEWEB)

    1921-11-05

    This invention has for its object a process of distillation, fractional, and continuous, of shale oil, tar, etc., characterized by the vapors leaving the evaporation chamber being forced, before condensation, to go over a continuous circuit. The vapors traverse first a preheater then return to the vaporization chamber in which they are passed along large surfaces and by application of the counter-current principle in contact with the liquid to be distilled. They stream through the chamber in a continuous manner (the quantity of vapor emitted in the circuit being determined in a manner to advance the distillation just to completion); the excess of vapor formed being removed from the circuit and sent to a condensing apparatus for fractionation.

  12. Search for free fractional charge

    International Nuclear Information System (INIS)

    Heilig, S.J.

    1985-01-01

    Recent results of searches for free fractional charge have been null with the exception of the experiment at Stanford under the leadership of W. Fairbank. His experiment, while claiming the observation of free fractional charge, has yet to show that this observation was not spurious. The need for a confirming experiment with a different physical system is the motivation for the current work. A torsional pendulum has been constructed of a fused silica fiber with an attached fused silica crossbar. A transverse electric field is applied to the end of the crossbar, and the resulting deflection of the crossbar is used to measure the torque applied by the field. To date the limit of measurement for the charge on the crossbar (without sample) is 0 +/- 24 electronic charges. The history of this experiment is discussed, along with plans for pushing the limits of measurement to below the single-charge level

  13. Topological transformation of fractional optical vortex beams using computer generated holograms

    Science.gov (United States)

    Maji, Satyajit; Brundavanam, Maruthi M.

    2018-04-01

    Optical vortex beams with fractional topological charges (TCs) are generated by the diffraction of a Gaussian beam using computer generated holograms embedded with mixed screw-edge dislocations. When the input Gaussian beam has a finite wave-front curvature, the generated fractional vortex beams show distinct topological transformations in comparison to the integer charge optical vortices. The topological transformations at different fractional TCs are investigated through the birth and evolution of the points of phase singularity, the azimuthal momentum transformation, occurrence of critical points in the transverse momentum and the vorticity around the singular points. This study is helpful to achieve better control in optical micro-manipulation applications.

  14. Measuring condensate fraction in superconductors

    International Nuclear Information System (INIS)

    Chakravarty, Sudip; Kee, Hae-Young

    2000-01-01

    An analysis of off-diagonal long-range order in superconductors shows that the spin-spin correlation function is significantly influenced by the order if the order parameter is anisotropic on a microscopic scale. Thus, magnetic neutron scattering can provide a direct measurement of the condensate fraction of a superconductor. It is also argued that recent measurements in high-temperature superconductors come very close to achieving this goal. (c) 2000 The American Physical Society

  15. Surfaces allowing for fractional statistics

    International Nuclear Information System (INIS)

    Aneziris, Charilaos.

    1992-07-01

    In this paper we give a necessary condition in order for a geometrical surface to allow for Abelian fractional statistics. In particular, we show that such statistics is possible only for two-dimentional oriented surfaces of genus zero, namely the sphere S 2 , the plane R 2 and the cylindrical surface R 1 *S 1 , and in general the connected sum of n planes R 2 -R 2 -R 2 -...-R 2 . (Author)

  16. Electrochemically controlled iron isotope fractionation

    Science.gov (United States)

    Black, Jay R.; Young, Edward D.; Kavner, Abby

    2010-02-01

    Variations in the stable isotope abundances of transition metals have been observed in the geologic record and trying to understand and reconstruct the physical/environmental conditions that produced these signatures is an area of active research. It is clear that changes in oxidation state lead to large fractionations of the stable isotopes of many transition metals such as iron, suggesting that transition metal stable isotope signatures could be used as a paleo-redox proxy. However, the factors contributing to these observed stable isotope variations are poorly understood. Here we investigate how the kinetics of iron redox electrochemistry generates isotope fractionation. Through a combination of electrodeposition experiments and modeling of electrochemical processes including mass-transport, we show that electron transfer reactions are the cause of a large isotope separation, while mass transport-limited supply of reactant to the electrode attenuates the observed isotopic fractionation. Furthermore, the stable isotope composition of electroplated transition metals can be tuned in the laboratory by controlling parameters such as solution chemistry, reaction overpotential, and solution convection. These methods are potentially useful for generating isotopically-marked metal surfaces for tracking and forensic purposes. In addition, our studies will help interpret stable isotope data in terms of identifying underlying electron transfer processes in laboratory and natural samples.

  17. Exploring the applications of fractional calculus: Hierarchically built semiflexible polymers

    International Nuclear Information System (INIS)

    Fürstenberg, Florian; Dolgushev, Maxim; Blumen, Alexander

    2015-01-01

    In this article we study, through extensions of the generalized Gaussian scheme, the dynamics of semiflexible treelike polymers under the influence of external forces acting on particular (say, charged) monomers. Semiflexibility is introduced following our previous work (Dolgushev and Blumen, 2009 [15]), a procedure which allows one to study treelike structures with arbitrary stiffness and branching. Exemplarily, we illustrate the procedure using linear chains and hyperbranched polymers modeled through Vicsek fractals, and obtain in every case the monomer displacement averaged over the structure. Anomalous behavior manifests itself in the intermediate time region, where the different fractal architectures show distinct scaling behaviors. These behaviors are due to the power law behavior of the spectral density and lead, for arbitrary pulling forces, based on causality and the linear superposition principle, to fractional calculus expressions, in accordance to former phenomenological fractional laws in polymer physics.

  18. Common and distinct components in data fusion

    DEFF Research Database (Denmark)

    Smilde, Age Klaas; Mage, Ingrid; Næs, Tormod

    2016-01-01

    and understanding their relative merits. This paper provides a unifying framework for this subfield of data fusion by using rigorous arguments from linear algebra. The most frequently used methods for distinguishing common and distinct components are explained in this framework and some practical examples are given...

  19. Knowledge Affords Distinctive Processing in Memory

    Science.gov (United States)

    Hunt, R. Reed; Rawson, Katherine A.

    2011-01-01

    The effect of knowledge on memory generally is processing. However, both conceptual and empirical reasons exist to suspect that the organizational account is incomplete. Recently a revised version of that account has been proposed under the rubric of distinctiveness theory (Rawson & Van Overschelde, 2008). The goal of the experiments reported…

  20. Distinctiveness of Saudi Arabian EFL Learners

    Science.gov (United States)

    Habbash, Manssour; Idapalapati, Srinivasa Rao

    2016-01-01

    In view of the increasing concern among English language teachers dealing with students from Saudi Arabia, as it manifests in TESOL community discussions, about the uniqueness of Saudi Arabian EFL learners, this paper attempts to document the outcome of a study of their distinctiveness from the perspective of expatriate teachers working for PYPs…

  1. Developmental Growth Trajectories in Understanding of Fraction Magnitude from Fourth through Sixth Grade

    Science.gov (United States)

    Resnick, Ilyse; Jordan, Nancy C.; Hansen, Nicole; Rajan, Vinaya; Rodrigues, Jessica; Siegler, Robert S.; Fuchs, Lynn S.

    2016-01-01

    Development of fraction number line estimation was assessed longitudinally over 5 time points between 4th and 6th grades. Although students showed positive linear growth overall, latent class growth analyses revealed 3 distinct growth trajectory classes: Students who were highly accurate from the start and became even more accurate (n = 154);…

  2. The fractional quantum Hall effect

    International Nuclear Information System (INIS)

    Stormer, H.L.

    1988-01-01

    The fractional quantum Hall effect (FQHE), is the manifestation of a new, highly correlated, many-particle ground state that forms in a two-dimensional electron system at low temperatures and in high magnetic fields. It is an example of the new physics that has grown out of the tremendous recent advances in semiconductor material science, which has provided us with high-quality, lower-dimensional carrier systems. The novel electronic state exposes itself in transport experiments through quantization of the Hall resistance to an exact rational fraction of h/e, and concomitantly vanishing longitudinal resistivity. Its relevant energy scale is only a few degrees kelvin. The quantization is a consequence of the spontaneous formation of an energy gap separating the condensed ground state from its rather elusive quasiparticle excitations. The theoretical understanding of the novel quantum liquids which underlie the FQHE has predominantly emerged from an ingenious many-particle wave function strongly supported by numerous few-particle simulations. Theory has now constructed a complex model for ideal two-dimensional electron systems in the presence of high magnetic fields and makes definitive, often fascinating predictions. Experiments have successively uncovered odd-denominator fractional states reaching presently to 7/13. The application of new experimental tools to the FQHE, such as optics, microwaves, and phonon techniques promises the direct observation of such parameters as the gap energy and possibly even some of the more elusive quantities in the future. While theory and experiment in the FQHE appear to be converging, there remains considerable room for challenging surprises. This paper provides a concise overview of the FQHE. It focuses on the experimental aspects and states, but does not expand on the theoretical advances. 70 refs., 11 figs

  3. Low power constant fraction discriminator

    International Nuclear Information System (INIS)

    Krishnan, Shanti; Raut, S.M.; Mukhopadhyay, P.K.

    2001-01-01

    This paper describes the design of a low power ultrafast constant fraction discriminator, which significantly reduces the power consumption. A conventional fast discriminator consumes about 1250 MW of power whereas this low power version consumes about 440 MW. In a multi detector system, where the number of discriminators is very large, reduction of power is of utmost importance. This low power discriminator is being designed for GRACE (Gamma Ray Atmospheric Cerenkov Experiments) telescope where 1000 channels of discriminators are required. A novel method of decreasing power consumption has been described. (author)

  4. Natural fractionation of uranium isotopes

    International Nuclear Information System (INIS)

    Noordmann, Janine

    2015-01-01

    The topic of this thesis was the investigation of U (n( 238 U) / n( 235 U)) isotope variations in nature with a focus on samples (1) that represent the continental crust and its weathering products (i.e. granites, shales and river water) (2) that represent products of hydrothermal alteration on mid-ocean ridges (i.e. altered basalts, carbonate veins and hydrothermal water) and (3) from restricted euxinic basins (i.e. from the water column and respective sediments). The overall goal was to explore the environmental conditions and unravel the mechanisms that fractionate the two most abundant U isotopes, n( 238 U) and n( 235 U), on Earth.

  5. Fractional separation of hydrocarbon vapours

    Energy Technology Data Exchange (ETDEWEB)

    1937-07-10

    A process is described for converting higher boiling hydrocarbons to lower boiling hydrocarbons by subjecting them at elevated temperatures to a conversion operation, then separating the higher and lower boiling fractions. The separation takes place while the reaction products are maintained in the vapor phase by contact with a mass of solid porous material which has little or no catalytic activity but does have a preferential absorption property for higher boiling hydrocarbons so that the lower boiling part of the reaction products pass through the separation zone while the heavier hydrocarbons are retained. The separation is accomplished without substantial loss of heat of these reaction products.

  6. Embarrassment: its distinct form and appeasement functions.

    Science.gov (United States)

    Keltner, D; Buswell, B N

    1997-11-01

    The authors address 2 questions about embarrassment. First, Is embarrassment a distinct emotion? The evidence indicates that the antecedents, experience, and display of embarrassment, and to a limited extent its autonomic physiology, are distinct from shame, guilt, and amusement and share the dynamic, temporal characteristics of emotion. Second, What are the theoretical accounts of embarrassment? Three accounts focus on the causes of embarrassment, positioning that it follows the loss of self-esteem, concern for others' evaluations, or absence of scripts to guide interactions. A fourth account focuses on the effects of the remedial actions of embarrassment, which correct preceding transgressions. A fifth account focuses on the functional parallels between embarrassment and nonhuman appeasement. The discussion focuses on unanswered questions about embarrassment.

  7. Distinctive skeletal dysplasia in Cockayne syndrome

    International Nuclear Information System (INIS)

    Silengo, M.C.; Franceschini, P.; Bianco, R.; Biagioli, M.; Pastorin, L.; Vista, N.; Baldassar, A.; Benso, L.

    1986-01-01

    Cockayne syndrom is a well-known autosomal recessive form of dwarfism with senile-like appearance. Skeletal changes such as flattening of vertebral bodies, ivory epiphyses and thickening of cranial vault, have been observed in some patients with this condition. We describe here a 5.5-year-old girl with the typical clinical signs of Cockayne syndrome and a distinctive form of bone dysplasia with major involvment of the spine. (orig.)

  8. Distinctive skeletal dysplasia in Cockayne syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Silengo, M.C.; Franceschini, P.; Bianco, R.; Biagioli, M.; Pastorin, L.; Vista, N.; Baldassar, A.; Benso, L.

    1986-03-01

    Cockayne syndrome is a well-known autosomal recessive form of dwarfism with senile-like appearance. Skeletal changes such as flattening of vertebral bodies, ivory epiphyses and thickening of cranial vault, have been observed in some patients with this condition. We describe here a 5.5-year-old girl with the typical clinical signs of Cockayne syndrome and a distinctive form of bone dysplasia with major involvement of the spine.

  9. Army nurses in wartime: distinction and pride.

    Science.gov (United States)

    Higgins, L P

    1996-08-01

    Nurses have served with distinction in wartime since Florence Nightingale went to the Crimea. Women often accompanied their husbands to battle during the Revolutionary and Civil Wars, caring for the sick and wounded. Although not officially given officer status until 1920, Army nurses served in the Spanish-American War and World War I. As officers, thousands of nurses served in subsequent wars, distinguishing themselves by their heroism, devotion to duty, and sheer tenacity of spirit.

  10. On the fractional systems fault detection: a comparison between fractional and rational residual sensitivity

    International Nuclear Information System (INIS)

    Aoun, M.; Aribi, A.; Najar, S.; Abdelkrim, M.N.

    2011-01-01

    This paper shows the interest of extending the dynamic parity space fault detection method for fractional systems. Accordingly, a comparison between fractional and rational residual generators using the later method is presented. An analysis of fractional and rational residuals sensitivity shows the merits of the fractional residual generators. A numerical example illustrating the advantage of using fractional residual generators for fractional systems diagnosis is given.

  11. THE NEW SOLUTION OF TIME FRACTIONAL WAVE EQUATION WITH CONFORMABLE FRACTIONAL DERIVATIVE DEFINITION

    OpenAIRE

    Çenesiz, Yücel; Kurt, Ali

    2015-01-01

    – In this paper, we used new fractional derivative definition, the conformable fractional derivative, for solving two and three dimensional time fractional wave equation. This definition is simple and very effective in the solution procedures of the fractional differential equations that have complicated solutions with classical fractional derivative definitions like Caputo, Riemann-Liouville and etc. The results show that conformable fractional derivative definition is usable and convenient ...

  12. Nonlinear dynamics of fractional order Duffing system

    International Nuclear Information System (INIS)

    Li, Zengshan; Chen, Diyi; Zhu, Jianwei; Liu, Yongjian

    2015-01-01

    In this paper, we analyze the nonlinear dynamics of fractional order Duffing system. First, we present the fractional order Duffing system and the numerical algorithm. Second, nonlinear dynamic behaviors of Duffing system with a fixed fractional order is studied by using bifurcation diagrams, phase portraits, Poincare maps and time domain waveforms. The fractional order Duffing system shows some interesting dynamical behaviors. Third, a series of Duffing systems with different fractional orders are analyzed by using bifurcation diagrams. The impacts of fractional orders on the tendency of dynamical motion, the periodic windows in chaos, the bifurcation points and the distance between the first and the last bifurcation points are respectively studied, in which some basic laws are discovered and summarized. This paper reflects that the integer order system and the fractional order one have close relationship and an integer order system is a special case of fractional order ones.

  13. A fractional model for dye removal

    Directory of Open Access Journals (Sweden)

    Ji-Huan He

    2016-01-01

    Full Text Available The adsorption process has a fractional property, and a fractional model is suggested to study a transport model of direct textile industry wastewater. An approximate solution of the concentration is obtained by the variational iteration method.

  14. Boundary Controllability of Nonlinear Fractional Integrodifferential Systems

    Directory of Open Access Journals (Sweden)

    Ahmed HamdyM

    2010-01-01

    Full Text Available Sufficient conditions for boundary controllability of nonlinear fractional integrodifferential systems in Banach space are established. The results are obtained by using fixed point theorems. We also give an application for integropartial differential equations of fractional order.

  15. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  16. Chaos in discrete fractional difference equations

    Indian Academy of Sciences (India)

    2016-09-07

    Sep 7, 2016 ... chaotic behaviour of fractional difference equations for the tent map, Gauss map and 2x(mod 1) map are studied ..... (4) No significant change is observed by changing .... (3) In fractional case, the rational initial condition.

  17. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa; Salama, Khaled N.; Shamim, Atif

    2014-01-01

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha

  18. Fractionated stereotactic radiotherapy for craniopharyngiomas

    International Nuclear Information System (INIS)

    Schulz-Ertner, Daniela; Frank, Claudia; Herfarth, Klaus K.; Rhein, Bernhard; Wannenmacher, Michael; Debus, Juergen

    2002-01-01

    Purpose: To investigate outcome and toxicity after fractionated stereotactic radiation therapy (FSRT) in patients with craniopharyngiomas. Methods and Materials: Twenty-six patients with craniopharyngiomas were treated with FSRT between May 1989 and February 2001. Median age was 33.5 years (range: 5-57 years). Nine patients received FSRT after surgery as primary treatment, and 17 patients were irradiated for recurrent tumor or progressive growth after initial surgery. Median target dose was 52.2 Gy (range: 50.0-57.6 Gy) with conventional fractionation. Follow-up included MRI and neurologic, ophthalmologic, and endocrinologic examinations. Results: The median follow-up was 43 months (range: 7-143 months). The actuarial local control rate and actuarial overall survival rates were 100% and 100%, respectively, at 5 years and 100% and 83%, respectively, at 10 years. Four patients showed complete response, 14 patients showed partial response, and 8 patients remained stable. In 5 patients, vision improved after radiation therapy. Acute toxicity was mild. One patient required cyst drainage 3 months after radiotherapy. Late toxicity after radiotherapy included impairment of hormone function in 3 out of 18 patients at risk. We did not observe any vision impairment, radionecrosis, or secondary malignancies. Conclusions: FSRT is effective and safe in the treatment of cystic craniopharyngiomas. Toxicity is extremely low using this conformal technique

  19. Inhibition of Neuroblastoma cancer cells viability by ferromagnetic Mn doped CeO{sub 2} monodisperse nanoparticles mediated through reactive oxygen species

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Fazal; Jan, Tariq [Laboratory of Nanoscience and Technology (LNT), Department of Physics, International Islamic University Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@iiu.edu.pk [Laboratory of Nanoscience and Technology (LNT), Department of Physics, International Islamic University Islamabad (Pakistan); Haider Naqvi, M. Sajjad [Department of Biochemistry, University of Karachi, Karachi (Pakistan); Ahmad, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan)

    2016-04-15

    Here we report the Mn doping induced effects on structural, Raman, optical, magnetic and anticancer properties of CeO{sub 2} nanoparticles prepared via soft chemical route. Structural and microstructural results infer that the synthesized nanoparticles have single phase cubic fluorite structure of CeO{sub 2} and that Mn doping results in enhancement of the structural defects. Scanning electron microscopy results reveal the formation of monodisperse nanoparticles having average particle size ranging from 30 to 41 nm. The optical absorbance spectroscopy analysis discloses the band gap energy tailoring of CeO{sub 2} nanoparticles via Mn doping. Room temperature ferromagnetism (RTFM) has been found in both as-prepared and Mn doped CeO{sub 2} nanoparticles. This RTFM of the synthesized nanoparticles have been attributed to the Mn ions and surface defects such as oxygen vacancies. Finally, the influence of Mn dopant on the cell viability and reactive oxygen species (ROS) generation levels of CeO{sub 2} nanoparticles in the presence of healthy and cancerous cells have been studied. It has been observed that the differential cytotoxicity of the synthesized nanoparticles is strongly correlated with level of ROS generation. - Highlights: • Mn doped CeO{sub 2} nanoparticles with cubic fluorite structure were synthesized. • Mn dopant significantly tailored the band gap of CeO{sub 2} nanoparticles. • The synthesized nanoparticles exhibited room temperature ferromagnetic behavior. • The cytotoxicity of these nanoparticles was reported for the first time. • The synthesized nanoparticles exhibited differential cytotoxicity.

  20. The synchronization of three fractional differential systems

    International Nuclear Information System (INIS)

    Li Changpin; Yan Jianping

    2007-01-01

    In this paper, a new method is proposed and applied to the synchronization of fractional differential systems (or 'differential systems with fractional orders'), where both drive and response systems have the same dimensionality and are coupled by the driving signal. The present technique is based on the stability criterion of linear fractional systems. This method is implemented in (chaos) synchronization of the fractional Lorenz system, Chen system and Chua circuit. Numerical simulations show the present synchronization method works well

  1. Multivariate fractional Poisson processes and compound sums

    OpenAIRE

    Beghin, Luisa; Macci, Claudio

    2015-01-01

    In this paper we present multivariate space-time fractional Poisson processes by considering common random time-changes of a (finite-dimensional) vector of independent classical (non-fractional) Poisson processes. In some cases we also consider compound processes. We obtain some equations in terms of some suitable fractional derivatives and fractional difference operators, which provides the extension of known equations for the univariate processes.

  2. Time-fractional particle deposition in porous media

    Science.gov (United States)

    Xu, Jianping

    2017-05-01

    In the percolation process where fluids carry small solid particles, particle deposition causes a real-time permeability change of the medium as the swarm of particles propagates along the medium. Then the permeability change influences percolation and deposition behaviors as a feedback. This fact triggers memory effect in the deposition dynamics, which means the particulate transport and deposition behaviors become history-dependent. In this paper, we conduct the time-fractional generalization of the classical phenomenological model of particle deposition in porous media to incorporate the memory effect. We tested and compared the effects of employing different types of fractional operators, i.e. the Riemann-Liouville type, the Hadamard type and the Prabhakar type. Numerical simulation results show that the system behaviors vary according to the change of distinct memory kernels in an expected way. We then discuss the physical meaning of the time-fractional generalization. It is shown that different types of fractional operators unanimously ground themselves on the local-Newtonian time transformation in a complex system, which is equivalent to a class of history integrals. By the introduction of various memory kernels, it enables the model to more powerfully fit and approximate observed data. Further, the fundamental meaning of this work is not to show which fractional operator is ‘better’, but to argue collectively the legitimacy and practicality of a non-Markovian particle deposition dynamics in porous media, and in fact it is admissible to a bunch of memory kernels which differ greatly from each other in functional forms. Hopefully the presented generalized mass conservation formalism offers a broader framework to investigate transport problems in porous media.

  3. Time-fractional particle deposition in porous media

    International Nuclear Information System (INIS)

    Xu, Jianping

    2017-01-01

    In the percolation process where fluids carry small solid particles, particle deposition causes a real-time permeability change of the medium as the swarm of particles propagates along the medium. Then the permeability change influences percolation and deposition behaviors as a feedback. This fact triggers memory effect in the deposition dynamics, which means the particulate transport and deposition behaviors become history-dependent. In this paper, we conduct the time-fractional generalization of the classical phenomenological model of particle deposition in porous media to incorporate the memory effect. We tested and compared the effects of employing different types of fractional operators, i.e. the Riemann–Liouville type, the Hadamard type and the Prabhakar type. Numerical simulation results show that the system behaviors vary according to the change of distinct memory kernels in an expected way. We then discuss the physical meaning of the time-fractional generalization. It is shown that different types of fractional operators unanimously ground themselves on the local-Newtonian time transformation in a complex system, which is equivalent to a class of history integrals. By the introduction of various memory kernels, it enables the model to more powerfully fit and approximate observed data. Further, the fundamental meaning of this work is not to show which fractional operator is ‘better’, but to argue collectively the legitimacy and practicality of a non-Markovian particle deposition dynamics in porous media, and in fact it is admissible to a bunch of memory kernels which differ greatly from each other in functional forms. Hopefully the presented generalized mass conservation formalism offers a broader framework to investigate transport problems in porous media. (paper)

  4. Microwave absorption enhancement, magnetic coupling and ab initio electronic structure of monodispersed (Mn1-xCox)3O4 nanoparticles

    Science.gov (United States)

    Zhao, Pengfei; Liang, Chongyun; Gong, Xiwen; Gao, Ran; Liu, Jiwei; Wang, Min; Che, Renchao

    2013-08-01

    Monodispersed manganese oxide (Mn1-xCox)3O4 (0 nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to 100 °C, without any inertia gas for protection. The influences of the Co dopant content on the critical reaction temperature required for the nanoparticle formation, electronic band structures, magnetic properties, and the microwave absorption capability of (Mn1-xCox)3O4 are comprehensively investigated by means of both experimental and theoretical approaches including powder X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), super conductivity quantum interference device (SQUID) examination, and first-principle simulations. Co is successfully doped into the Mn atomic sites of the (Mn1-xCox)3O4 lattice, which is further confirmed by EELS data acquired from one individual nanoparticle. Therefore, continuous solid solutions of well-crystallized (Mn1-xCox)3O4 products are achieved without any impurity phase or phase separation. With increases in the Co dopant concentration x from 0 to 0.5, the lattice parameters change systemically, where the overall saturation magnetization at 30 K increases due to the more intense coupling of the 3d electrons between Mn and Co, as revealed by simulations. The microwave absorption properties of the (Mn1-xCox)3O4 nanoparticles are examined between 2 and 18 GHz. The maximum absorption peak -11.0 dB of the x = 0 sample is enhanced to -11.5 dB for x = 0.2, -12.7 dB for x = 0.25, -15.6 dB for x = 0.33, and -24.0 dB for x = 0.5 respectively, suggesting the Co doping effects. Our results might provide novel insights into the understanding of the influences of metallic ion doping on the electromagnetic properties of metallic oxide nanomaterials.Monodispersed manganese oxide (Mn1-xCox)3O4 (0 nanoparticles, less than 10 nm size, are respectively synthesized via a facile thermolysis method at a rather low temperature, ranging from 90 to

  5. Early Predictors of Middle School Fraction Knowledge

    Science.gov (United States)

    Bailey, Drew H.; Siegler, Robert S.; Geary, David C.

    2014-01-01

    Recent findings that earlier fraction knowledge predicts later mathematics achievement raise the question of what predicts later fraction knowledge. Analyses of longitudinal data indicated that whole number magnitude knowledge in first grade predicted knowledge of fraction magnitudes in middle school, controlling for whole number arithmetic…

  6. 16 CFR 500.17 - Fractions.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Fractions. 500.17 Section 500.17 Commercial... LABELING ACT § 500.17 Fractions. (a) SI metric declarations of net quantity of contents of any consumer commodity may contain only decimal fractions. Other declarations of net quantity of contents may contain...

  7. Teaching Fractions. Educational Practices Series-22

    Science.gov (United States)

    Fazio, Lisa; Siegler, Robert

    2011-01-01

    Students around the world have difficulties in learning about fractions. In many countries, the average student never gains a conceptual knowledge of fractions. This research guide provides suggestions for teachers and administrators looking to improve fraction instruction in their classrooms or schools. The recommendations are based on a…

  8. On varitional iteration method for fractional calculus

    Directory of Open Access Journals (Sweden)

    Wu Hai-Gen

    2017-01-01

    Full Text Available Modification of the Das’ variational iteration method for fractional differential equations is discussed, and its main shortcoming involved in the solution process is pointed out and overcome by using fractional power series. The suggested computational procedure is simple and reliable for fractional calculus.

  9. An Alternative Starting Point for Fraction Instruction

    Science.gov (United States)

    Cortina, José Luis; Višnovská, Jana; Zúñiga, Claudia

    2015-01-01

    We analyze the results of a study conducted for the purpose of assessing the viability of an alternative starting point for teaching fractions. The alternative is based on Freudenthal's insights about fraction as comparison. It involves portraying the entities that unit fractions quantify as always being apart from the reference unit, instead of…

  10. Fractional Euler Limits and Their Applications

    OpenAIRE

    MacNamara, Shev; Henry, Bruce I; McLean, William

    2016-01-01

    Generalisations of the classical Euler formula to the setting of fractional calculus are discussed. Compound interest and fractional compound interest serve as motivation. Connections to fractional master equations are highlighted. An application to the Schlogl reactions with Mittag-Leffler waiting times is described.

  11. Natural fractionation of uranium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Noordmann, Janine

    2015-01-24

    The topic of this thesis was the investigation of U (n({sup 238}U) / n({sup 235}U)) isotope variations in nature with a focus on samples (1) that represent the continental crust and its weathering products (i.e. granites, shales and river water) (2) that represent products of hydrothermal alteration on mid-ocean ridges (i.e. altered basalts, carbonate veins and hydrothermal water) and (3) from restricted euxinic basins (i.e. from the water column and respective sediments). The overall goal was to explore the environmental conditions and unravel the mechanisms that fractionate the two most abundant U isotopes, n({sup 238}U) and n({sup 235}U), on Earth.

  12. A distinction of two discourses concerning wellbeing

    DEFF Research Database (Denmark)

    Wistoft, Karen; Qvortrup, Lars

    2017-01-01

    and behavioral mental health interventions, while the latter defines wellbeing in positive terms with a focus on wellbeing as the result of learning and with pedagogical interventions that only indirectly can support the individual’s learning activity. The former sees wellbeing as the result of a “wellbeing cure......The article concerns the current discourses concerning well-being with the point that it is important to make a distinction between a healthcare oriented discourse and a learning oriented discourse. The former defines wellbeing in negative terms and looks at causally oriented aspects of wellbeing......”, while the latter sees wellbeing as the result of wellbeing learning processes....

  13. Approaching the Distinction between Intuition and Insight.

    Science.gov (United States)

    Zhang, Zhonglu; Lei, Yi; Li, Hong

    2016-01-01

    Intuition and insight share similar cognitive and neural basis. Though, there are still some essential differences between the two. Here in this short review, we discriminated between intuition, and insight in two aspects. First, intuition, and insight are toward different aspects of information processing. Whereas intuition involves judgment about "yes or no," insight is related to "what" is the solution. Second, tacit knowledge play different roles in between intuition and insight. On the one hand, tacit knowledge is conducive to intuitive judgment. On the other hand, tacit knowledge may first impede but later facilitate insight occurrence. Furthermore, we share theoretical, and methodological views on how to access the distinction between intuition and insight.

  14. Second Study of Hyper-Fractionated Radiotherapy

    Directory of Open Access Journals (Sweden)

    R. Jacob

    1999-01-01

    Full Text Available Purpose and Method. Hyper-fractionated radiotherapy for treatment of soft tissue sarcomas is designed to deliver a higher total dose of radiation without an increase in late normal tissue damage. In a previous study at the Royal Marsden Hospital, a total dose of 75 Gy using twice daily 1.25 Gy fractions resulted in a higher incidence of late damage than conventional radiotherapy using 2 Gy daily fractions treating to a total of 60 Gy. The current trial therefore used a lower dose per fraction of 1.2 Gy and lower total dose of 72 Gy, with 60 fractions given over a period of 6 weeks.

  15. Hamiltonian Chaos and Fractional Dynamics

    International Nuclear Information System (INIS)

    Combescure, M

    2005-01-01

    This book provides an introduction and discussion of the main issues in the current understanding of classical Hamiltonian chaos, and of its fractional space-time structure. It also develops the most complex and open problems in this context, and provides a set of possible applications of these notions to some fundamental questions of dynamics: complexity and entropy of systems, foundation of classical statistical physics on the basis of chaos theory, and so on. Starting with an introduction of the basic principles of the Hamiltonian theory of chaos, the book covers many topics that can be found elsewhere in the literature, but which are collected here for the readers' convenience. In the last three parts, the author develops topics which are not typically included in the standard textbooks; among them are: - the failure of the traditional description of chaotic dynamics in terms of diffusion equations; - he fractional kinematics, its foundation and renormalization group analysis; - 'pseudo-chaos', i.e. kinetics of systems with weak mixing and zero Lyapunov exponents; - directional complexity and entropy. The purpose of this book is to provide researchers and students in physics, mathematics and engineering with an overview of many aspects of chaos and fractality in Hamiltonian dynamical systems. In my opinion it achieves this aim, at least provided researchers and students (mainly those involved in mathematical physics) can complement this reading with comprehensive material from more specialized sources which are provided as references and 'further reading'. Each section contains introductory pedagogical material, often illustrated by figures coming from several numerical simulations which give the feeling of what's going on, and thus is very useful to the reader who is not very familiar with the topics presented. Some problems are included at the end of most sections to help the reader to go deeper into the subject. My one regret is that the book does not

  16. Utilization of Different Corn Fractions by Broilers

    Directory of Open Access Journals (Sweden)

    SIFR Costa

    2015-09-01

    Full Text Available ABSTRACTThis study was conducted to evaluate the nutritional values of fractions of damaged corn. One hundred and eighty 22-d-old Cobb 500 male broilers were distributed in batteries according to a completely randomized design with six treatments of six replicates each. The treatments consisted of diets containing five corn fractions, classified as sound, fermented, insect-damaged, mold-damaged, or reference corn. The test diets consisted of 60% of reference diet + 40% of each corn fraction. Only the reference corn fraction included all the fractions at different proportions (0.8% fermented, 0.05% insect-damaged, 3.3% mold-damaged, and 95.85% sound grains. The method of total excreta collection was used to determine AMEn values and metabolizability coefficients of dry matter (MDM, crude protein (MCP, ether extract (MEE, and gross energy (MGE of the reference corn and its fractions. The density values of the corn fractions were used to calculate the correlations among the evaluated parameters. The evaluated corn fractions presented different compositions values. The insect-damaged and mold-damaged grains presented higher CP level, lower density, and MDM and MCP coefficients compared with the other fractions. However, calculated AMEn values were not significantly different (p>0.05 among corn fractions. A low correlation between density and AMEn content (r0.8 were calculated. Although the evaluated corn fractions presented different nutritional values, there were no marked differences in their utilization by broilers.

  17. The fractional dynamics of quantum systems

    Science.gov (United States)

    Lu, Longzhao; Yu, Xiangyang

    2018-05-01

    The fractional dynamic process of a quantum system is a novel and complicated problem. The establishment of a fractional dynamic model is a significant attempt that is expected to reveal the mechanism of fractional quantum system. In this paper, a generalized time fractional Schrödinger equation is proposed. To study the fractional dynamics of quantum systems, we take the two-level system as an example and derive the time fractional equations of motion. The basic properties of the system are investigated by solving this set of equations in the absence of light field analytically. Then, when the system is subject to the light field, the equations are solved numerically. It shows that the two-level system described by the time fractional Schrödinger equation we proposed is a confirmable system.

  18. Local Fractional Laplace Variational Iteration Method for Solving Linear Partial Differential Equations with Local Fractional Derivative

    Directory of Open Access Journals (Sweden)

    Ai-Min Yang

    2014-01-01

    Full Text Available The local fractional Laplace variational iteration method was applied to solve the linear local fractional partial differential equations. The local fractional Laplace variational iteration method is coupled by the local fractional variational iteration method and Laplace transform. The nondifferentiable approximate solutions are obtained and their graphs are also shown.

  19. The neural signatures of distinct psychopathic traits.

    Science.gov (United States)

    Carré, Justin M; Hyde, Luke W; Neumann, Craig S; Viding, Essi; Hariri, Ahmad R

    2013-01-01

    Recent studies suggest that psychopathy may be associated with dysfunction in the neural circuitry supporting both threat- and reward-related processes. However, these studies have involved small samples and often focused on extreme groups. Thus, it is unclear to what extent current findings may generalize to psychopathic traits in the general population. Furthermore, no studies have systematically and simultaneously assessed associations between distinct psychopathy facets and both threat- and reward-related brain function in the same sample of participants. Here, we examined the relationship between threat-related amygdala reactivity and reward-related ventral striatum (VS) reactivity and variation in four facets of self-reported psychopathy in a sample of 200 young adults. Path models indicated that amygdala reactivity to fearful facial expressions is negatively associated with the interpersonal facet of psychopathy, whereas amygdala reactivity to angry facial expressions is positively associated with the lifestyle facet. Furthermore, these models revealed that differential VS reactivity to positive versus negative feedback is negatively associated with the lifestyle facet. There was suggestive evidence for gender-specific patterns of association between brain function and psychopathy facets. Our findings are the first to document differential associations between both threat- and reward-related neural processes and distinct facets of psychopathy and thus provide a more comprehensive picture of the pattern of neural vulnerabilities that may predispose to maladaptive outcomes associated with psychopathy.

  20. The Distinction Between Curative and Assistive Technology.

    Science.gov (United States)

    Stramondo, Joseph A

    2018-05-01

    Disability activists have sometimes claimed their disability has actually increased their well-being. Some even say they would reject a cure to keep these gains. Yet, these same activists often simultaneously propose improvements to the quality and accessibility of assistive technology. However, for any argument favoring assistive over curative technology (or vice versa) to work, there must be a coherent distinction between the two. This line is already vague and will become even less clear with the emergence of novel technologies. This paper asks and tries to answer the question: what is it about the paradigmatic examples of curative and assistive technologies that make them paradigmatic and how can these defining features help us clarify the hard cases? This analysis will begin with an argument that, while the common views of this distinction adequately explain the paradigmatic cases, they fail to accurately pick out the relevant features of those technologies that make them paradigmatic and to provide adequate guidance for parsing the hard cases. Instead, it will be claimed that these categories of curative or assistive technologies are defined by the role the technologies play in establishing a person's relational narrative identity as a member of one of two social groups: disabled people or non-disabled people.