WorldWideScience

Sample records for content nano-composite dense

  1. Nano-composite materials

    Science.gov (United States)

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

    2010-05-25

    Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

  2. Polymer/Layered Silicate Nano composites

    International Nuclear Information System (INIS)

    Bakhit, M.E.E.H.

    2012-01-01

    Polymer–clay nano composites have attracted the attention of many researchers and experimental results are presented in a large number of recent papers and patents because of the outstanding mechanical properties and low gas permeabilities that are achieved in many cases. Polymer-clay nano composites are a new class of mineral-field polymer that contain relatively small amounts (<10%) of nanometer-sized clay particles. Polymer/clay nano composites have their origin in the pioneering research conducted at Toyota Central Research Laboratories and the first historical record goes back to 1987. The matrix was nylon-6 and the filler MMT. Because of its many advantages such as high mechanical properties, good gas barrier, flame retardation, etc. polymer/clay nano composites have been intensely investigated and is currently the subject of many research programs. Nano composite materials are commercially important and several types of products with different shapes and applications including food packaging films and containers, engine parts, dental materials, etc. are now available in markets. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or prepolymers from solution, in-situ polymerization, melt intercalation etc. In this study, new nano composite materials were produced from the components of rubber (Nbr, SBR and EPDM) as the polymeric matrix and organically modified quaternary alkylammonium montmorillonite in different contents (3, 5, 7, and 10 phr) as the filler by using an extruder then, the rubber nano composite sheets were irradiated at a dose of 0, 50, 75, 100 and 150 KGy using Electron beam Irradiation technique as a crosslinking agent. These new materials can be characterized by using various analytical techniques including X-ray diffractometer XRD, Thermogravimetric analyzer TGA, scanning electron microscope (SEM), transmission electron microscope (TEM),Fourier transform

  3. Effect of antimicrobial agents on cellulose acetate nano composites properties

    International Nuclear Information System (INIS)

    Rodriguez, Francisco J.; Bruna, Julio E.; Galotto, Maria J.; Guarda, Abel; Sepulveda, Hugo

    2011-01-01

    Nano composites based on cellulose acetate, Cloisite 30B, triethyl citrate and thymol or cinnamaldehyde were prepared using a dissolution casting technique. The effect of thymol and cinnamaldehyde on the cellulose acetate nano composite properties was evaluated by XRD and DSC. Important changes on the thermal properties and morphological structure were observed according to thymol and cinnamaldehyde content. (author)

  4. Effect of antimicrobial agents on cellulose acetate nano composites properties

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Francisco J.; Bruna, Julio E.; Galotto, Maria J.; Guarda, Abel; Sepulveda, Hugo, E-mail: francisco.rodriguez.m@usach.cl [Center for the Development of Nanoscience and Nanotechnology (CEDENNA). Universidad de Santiago de Chile. Faculty of Technology. Department of Food Science and Technology. Food Packaging Laboratory. Santiago (Chile)

    2011-07-01

    Nano composites based on cellulose acetate, Cloisite 30B, triethyl citrate and thymol or cinnamaldehyde were prepared using a dissolution casting technique. The effect of thymol and cinnamaldehyde on the cellulose acetate nano composite properties was evaluated by XRD and DSC. Important changes on the thermal properties and morphological structure were observed according to thymol and cinnamaldehyde content. (author)

  5. Effect of cobalt content on wear and corrosion behaviors of electrodeposited Ni-Co/WC nano-composite coatings.

    Science.gov (United States)

    Amadeh, A; Ebadpour, R

    2013-02-01

    Metal-ceramic composite coatings are widely used in automotive and aerospace industries as well as micro-electronic systems. Electrodeposition is an economic method for application of these coatings. In this research, nickel-cobalt coatings reinforced by nano WC particles were applied on carbon steel substrate by pulse electrodeposition from modified Watts bath containing different amounts of cobalt sulphate as an additive. Saccharin and sodium dodecyl sulphate (SDS) were also added to electroplating bath as grain refiner and surfactant, respectively. The effect of cobalt content on wear and corrosion behavior of the coatings was investigated. Wear and corrosion properties were assessed by pin-on-disk and potentiodynamic polarization methods, respectively. Phase analysis was performed by X-ray diffraction (XRD) using CuK(alpha) radiation and the worn surfaces were studied by means of Scanning Electron Microscopy (SEM). The results showed that the addition of cobalt improved the wear resistance of the coatings. In the presence of 18 g/L cobalt in electrodeposition bath, the wear rate of the coating decreased to 0.002 mg/m and the coefficient of friction reduced to 0.695 while they were 0.004 mg/m and 0.77 in the absence of cobalt, respectively. This improvement in wear properties can be attributed to the formation of hcp phase in metallic matrix. Meanwhile, the corrosion resistance of the coatings slightly reduced because cobalt is more active metal with respect to nickel.

  6. Preparation of polymer-organo clay nano composites through the spray drying process

    International Nuclear Information System (INIS)

    Bernardo, Paulo R.A.; Pessan, Luiz A.; Carvalho, Antonio J.F. de; Vidotti, Suel E.

    2011-01-01

    The objective of the work was the study and preparation of polymer nano composites with montmorillonite organo clays (MMT) through the spray drying process. A new technique was proposed and tested to obtaining polymer nano composites, based on the use of the spray drying process to produce a nano composite with high clay content. The process consisted of the following stages: clay intercalation in water solution, with after addition of polyvinyl alcohol (PVOH) and a hydro soluble polyester ionomer (GEROLPS20) as exfoliation agents; spray drying the mixture obtained; incorporation powder in EVOH, PET e PP matrix. The effects of exfoliation agent on morphological and thermal properties of the nano composites were studied by XRD, transmission electron microscopy (TEM) and TGA. The results demonstrate that the process of spray drying is an innovative way to obtain a nano composite with high clay content. (author)

  7. Study on Carbon Nano composite Counter electrode for Dye-Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Chen, Y.; Zhang, H.; Lin, J.

    2012-01-01

    Carbon nano composite electrodes were prepared by adding carbon nano tubes (CNTs) into carbon black as counter electrodes of dye-sensitized solar cells (DSSCs). The morphology and structure of carbon nano composite electrodes were studied by scanning electron microscopy. The influence of CNTs on the electrochemical performance of carbon nano composite electrodes is investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Carbon nano composite electrodes with CNTs exhibit a highly interconnected network structure with high electrical conductivity and good catalytic activity. The influence of different CNTs content in carbon nano composite electrodes on the open-circuit voltage, short-circuit current, and filling factor of DSSCs is also investigated. DSSCs with 10% CNTs content exhibit the best photovoltaic performance in our experiments.

  8. Synthesis of Metal Polymer Nano composites Using Ionizing Radiation

    International Nuclear Information System (INIS)

    Mostafa, R.S.S.

    2012-01-01

    we prepared a series of CdS/PVA and Ag/PVA nano composites via facile and novel synthetic steps. Our synthetic route is simpler; it does not need expensive oxidizing agents, surfactants, templates and complicated apparatus. The present work contains five chapters in addition to the list of figures, tables, abbreviations and references. The first two chapters are concerned with the introduction and reviews of previous studies. Chapter 3 describes the preparation methodology, experimental setup and techniques used in the CdS/PVA and Ag/PVA nano composites processing and analysis. CdS and Ag nanoparticles with different particle sizes were prepared via chemical method and gamma irradiation method. Several techniques were used to detect the structural changes of the nano composites due to interaction between CdS or Ag ions and PVA. These are: UV-Visible spectrophotometer, Transmission Electron microscope (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) Spectrophotometer, and thermogravimetric analysis. Chapter 4 includes the obtained results and their discussions: Ultraviolet/Visible spectroscopy (UV/VIS) investigated that the as-prepared nano composites have improved optical properties. Such incremented optical properties were attributed to the nano scale dispersion (nm). The improvement in the optical properties is considered to be dependent on, Cd 2+ :S 2- molar ratio, Ag concentration, Pva content and irradiation dose. The calculated band gap energies for CdS/PVA nano composites are higher than that of bulk of CdS indicating the strong quantum confinement. The increases in band gap energy have been attributed to the crystalline size dependent properties. Transmission electron microscope images illustrated that the nano structured CdS/PVA films were found to be dispersed spherical nanoparticles with good structural homogeneity and polydispersity at either lower concentration of CdCl 2 and/or irradiation dose. Nano rod structure of CdS accompanied

  9. High performance nano-composite technology development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D. [KAERI, Taejon (Korea, Republic of); Kim, E. K.; Jung, S. Y.; Ryu, H. J. [KRICT, Taejon (Korea, Republic of); Hwang, S. S.; Kim, J. K.; Hong, S. M. [KIST, Taejon (Korea, Republic of); Chea, Y. B. [KIGAM, Taejon (Korea, Republic of); Choi, C. H.; Kim, S. D. [ATS, Taejon (Korea, Republic of); Cho, B. G.; Lee, S. H. [HGREC, Taejon (Korea, Republic of)

    1999-06-15

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  10. High performance nano-composite technology development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D. [KAERI, Taejon (Korea, Republic of); Kim, E. K.; Jung, S. Y.; Ryu, H. J. [KRICT, Taejon (Korea, Republic of); Hwang, S. S.; Kim, J. K.; Hong, S. M. [KIST, Taejon (Korea, Republic of); Chea, Y. B. [KIGAM, Taejon (Korea, Republic of); Choi, C. H.; Kim, S. D. [ATS, Taejon (Korea, Republic of); Cho, B. G.; Lee, S. H. [HGREC, Taejon (Korea, Republic of)

    1999-06-15

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  11. High performance nano-composite technology development

    International Nuclear Information System (INIS)

    Kim, Whung Whoe; Rhee, C. K.; Kim, S. J.; Park, S. D.; Kim, E. K.; Jung, S. Y.; Ryu, H. J.; Hwang, S. S.; Kim, J. K.; Hong, S. M.; Chea, Y. B.; Choi, C. H.; Kim, S. D.; Cho, B. G.; Lee, S. H.

    1999-06-01

    The trend of new material development are being to carried out not only high performance but also environmental attraction. Especially nano composite material which enhances the functional properties of components, extending the component life resulting to reduced the wastes and environmental contamination, has a great effect on various industrial area. The application of nano composite, depends on the polymer matrix and filler materials, has various application from semiconductor to medical field. In spite of nano composite merits, nano composite study are confined to a few special materials as a lab, scale because a few technical difficulties are still on hold. Therefore, the purpose of this study establishes the systematical planning to carried out the next generation projects on order to compete with other countries and overcome the protective policy of advanced countries with grasping over sea's development trends and our present status. (author).

  12. Preparation, Characterization, and Modeling of Carbon Nano fiber/Epoxy Nano composites

    International Nuclear Information System (INIS)

    Sun, L.H.; Yang, Z.G.; Ounaies, Z.; Whalen, C.A.; Gao, X.L.

    2011-01-01

    There is a lack of systematic investigations on both mechanical and electrical properties of carbon nano fiber (CNF)-reinforced epoxy matrix nano composites. In this paper, an in-depth study of both static and dynamic mechanical behaviors and electrical properties of CNF/epoxy nano composites with various contents of CNFs is provided. A modified Halpin-Tsai equation is used to evaluate the Young's modulus and storage modulus of the nano composites. The values of Young's modulus predicted using this method account for the effect of the CNF agglomeration and fit well with those obtained experimentally. The results show that the highest tensile strength is found in the epoxy nano composite with a 1.0 wt % CNFs. The alternate-current (AC) electrical properties of the CNF/epoxy nano composites exhibit a typical insulator-conductor transition. The conductivity increases by four orders of magnitude with the addition of 0.1 wt % (0.058 vol %) CNFs and by ten orders of magnitude for nano composites with CNF volume fractions higher than 1.0 wt % (0.578 vol %). The percolation threshold (i.e., the critical CNF volume fraction) is found to be at 0.057 vol %.

  13. Synthesis and characterization of new polyimide/organo clay nano composites containing benzophenone moieties in the main chain

    International Nuclear Information System (INIS)

    Faghihi, K.; Ashouri, M.; Feyzi, A.

    2013-01-01

    A series of nano composites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt %, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nano composite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane and 3,3,4,4-benzophenone tetra carboxylic dianhydride in N,N-dimethylacetamide (Dmac). The resulting nano composite films were characterized by Ft-IR spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. (Author)

  14. Synthesis and characterization of new polyimide/organo clay nano composites containing benzophenone moieties in the main chain

    Energy Technology Data Exchange (ETDEWEB)

    Faghihi, K.; Ashouri, M.; Feyzi, A., E-mail: k-faghihi@araku.ac.ir [Arak University, Faculty of Science, Organic Polymer Chemistry Research Laboratory, 38158-879 Arak (Iran, Islamic Republic of)

    2013-08-01

    A series of nano composites consist of organic polyimide and organo-modified clay content varying from 0 to 5 wt %, were successfully prepared by in situ polymerization. Polyimide used as a matrix of nano composite was prepared through the reaction of 1,4-bis [4-aminophenoxy] butane and 3,3,4,4-benzophenone tetra carboxylic dianhydride in N,N-dimethylacetamide (Dmac). The resulting nano composite films were characterized by Ft-IR spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric analysis. (Author)

  15. Comparison of the mechanical properties between carbon nanotube and nanocrystalline cellulose polypropylene based nano-composites

    International Nuclear Information System (INIS)

    Huang, Jun; Rodrigue, Denis

    2015-01-01

    Highlights: • SWCNT and NCC can effectively improve the mechanical properties of nano-composites. • SWCNT is more effective than NCC to increase modulus and strength. • Longer NCC is more effective to improve the mechanical properties of nano-composites. • It is more economic to use NCC than SWCNT to improve mechanical properties. - Abstract: Using beam and tetrahedron elements to simulate nanocrystalline cellulose (NCC), single wall carbon nanotube (SWCNT) and polypropylene (PP), finite element method (FEM) is used to predict the mechanical properties of nano-composites. The bending, shear and torsion behaviors of nano-composites are especially investigated due to the limited amount of information in the present literature. First, mixed method (MM) and FEM are used to compare the bending stiffness of NCC/PP and SWCNT/PP composites. Second, based on mechanics of materials, the shear moduli of both types of nano-composites are obtained. Finally, fixing the number of fibers and for different volume contents, four NCC lengths are used to determine the mechanical properties of the composites. The bending and shearing performances are also compared between NCC and SWCNT based composites. In all cases, the elastic–plastic analyses are carried out and the stress or strain distributions for specific regions are also investigated. From all the results obtained, an economic analysis shows that NCC is more interesting than SWCNT to reinforce PP

  16. Asphaltenes-based polymer nano-composites

    Science.gov (United States)

    Bowen, III, Daniel E

    2013-12-17

    Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

  17. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

    International Nuclear Information System (INIS)

    Debiagi, Flavia; Mali, Suzana

    2011-01-01

    The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

  18. Hybrid Nano composite Membranes for PEMFC Applications

    International Nuclear Information System (INIS)

    Niepceron, F.

    2008-03-01

    This work aims at validating a new concept of hybrid materials for the realization of proton exchange membranes, an essential constituent of PEM fuel cells. The originality of this nano-composite hybrid concept corresponds to a separation of the membrane's properties. We investigated the preparation of composite materials based on an inert, relatively low cost, polymer matrix (PVDF-HFP) providing the mechanical stability embedding inorganic fillers providing the necessary properties o f proton-conduction and water retention. The first step of this work consisted in the modification of fumed silica to obtain a proton-conducting filler. An ionic exchange capacity (CEI) equal to 3 meq/g was obtained by the original grafting of sodium poly(styrene-sulfonate) chains from the surface of particles. Nano-composite hybrid membranes PVDF-HFP/functionalized silica were accomplished by a film casting process. The coupling of the morphological and physicochemical analyses validated the percolation of the inorganic phase for 30 wt.% of particles. Beyond 40 % of loading, measured protonic conductivity is higher than the reference membrane Nafion 112. Finally, these membranes presented high performances, above 0.8 W/cm 2 , in single-cell fuel cell tests. A compromise is necessary according to the rate of loading between performances in fuel cell and mechanical properties of the membrane. 50 % appeared as best choice with, until 90 C, a remarkable thermal stability of the performances. (author)

  19. Modal analysis of pre and post impacted nano composite laminates

    Directory of Open Access Journals (Sweden)

    R. Velmurugan

    Full Text Available Modal analysis is carried out on pre and post impacted nano composite laminates. The laminates are prepared using 3, 5 and 8 layers of 610gsm glass woven roving mats(WRM with epoxy resin and montmorillonite(MMT clay content is varied from 1% to 5%. Impulse hammer technique is used to find natural frequency and damping factor of laminates. Medium velocity impact tests are conducted by using a gas gun. The vibration responses of natural frequency and damping factor are obtained and are studied for laminates with all edges clamped boundary conditions. Results show considerable improvement in natural frequency and damping factor due to nano clay addition. It is also seen that the nano clay controls the delamination due to impact loading.

  20. Structural and Magnetic Properties of Type-M Barium Ferrite - Thermoplastic Natural Rubber Nano composites

    International Nuclear Information System (INIS)

    Nurhidayaty Mokhtar

    2012-01-01

    Structural and magnetic properties of type-M barium ferrite (BaFe 12 O 19 ) nanoparticles (∼ 20 nm) embedded in non-magnetic thermoplastic natural rubber (TPNR) matrices were investigated. The TPNR matrices were prepared from high density polyethylene (HDPE) and natural rubber (NR) in the weight ratios of 80:20 and 60:40, respectively, with 10 wt % of NR in the form of liquid natural rubber (LNR) which act as a comparabilities. BaFe 12 O 19 - filled nano composites with 2 - 12 wt % BaFe 12 O 19 ferrite were prepared using a melt- blending technique. Magnetic hysteresis was measured using a vibrating sample magnetometer (VSM) in a maximum field of 10 kOe at room temperature (25 degree Celsius). The saturation magnetisation (MS), remanence (MR) and coercivity (Hc) were derived from the hysteresis loops. The results show that the structural and magnetic properties of nano composites depend on both the ferrite content and the composition of the natural rubber or plastic in the nano composites. All the nano composites exhibit an exchange bias-like phenomenon resulting from the exchange coupling of spins at the interface between the core ferrimagnetic region and the disordered surface region of the nanoparticles. (author)

  1. Stress development in particulate, nano-composite and polymeric coatings

    Science.gov (United States)

    Jindal, Karan

    2009-12-01

    The main goal of this research is to study the stress, structural and mechanical property development during the drying of particulate coatings, nano-composite coatings and VOC compliant refinish clearcoats. The results obtained during this research establish the mechanism for the stress development during drying in various coating systems. Coating stress was measured using a controlled environment stress apparatus based on cantilever deflection principle. The stress evolution in alumina coatings made of 0.4 mum size alumina particles was studied and the effect of a lateral drying was investigated. The stress does not develop until the later stages of drying. A peak stress was observed during drying and the peak stress originates due to the formation of pendular rings between the particles. Silica nanocomposite coatings were fabricated from suspension of nano sized silicon dioxide particles (20 nm) and polyvinyl alcohol (PVA) polymer. The stress in silica nano-composite goes through maximum as the amount of polymer in the coating increases. The highest final stress was found to be ˜ 110MPa at a PVA content of 60 wt%. Observations from SEM, nitrogen gas adsorption, camera imaging, and nano-indentation were also studied to correlate the coatings properties during drying to measured stress. A model VOC compliant two component (2K) acrylic-polyol refinish clearcoat was prepared to study the effects of a new additive on drying, curing, rheology and stress development at room temperature. Most of the drying of the low VOC coatings occurred before appreciable (20%) crosslinking. Tensile stress developed in the same timeframe as drying and then relaxed over a longer time scale. Model low VOC coatings prepared with the additive had higher peak stresses than those without the additive. In addition, rheological data showed that the additive resulted in greater viscosity buildup during drying.

  2. Preparation and characterization of PVC /ENR/CNTs Nano composites

    International Nuclear Information System (INIS)

    Ratnam, C.T.; Nur Azrini Ramlee; Keong, C.C.

    2011-01-01

    Poly (vinyl chloride), PVC/ epoxidized natural rubber blend, ENR/ carbon nano tubes, CNTs were prepared by using melt and solution blending methods. Addition of 2 phr of CNTs found to cause a drop in the tensile strength, Ts of the 50/ 50 PVC/ ENR blend. The nano composites prepared by the melt blending method exhibited higher values of Ts compared to the nano composites prepared by solution blending. Melt blending found to be an efficient method to prepare PVC/ ENR/ CNTs nano composites. (author)

  3. Flexural Properties of Activated Carbon Filled Epoxy Nano composites

    International Nuclear Information System (INIS)

    Khalil, H.P.S.A.; Khalil, H.P.S.A.; Alothman, O.Y.; Paridah, M.T.; Zainudin, E.S.

    2014-01-01

    Activated carbon (AC) filled epoxy nano composites obtained by mixing the desired amount of nano AC viz., bamboo stem, oil palm empty fruit bunch, and coconut shell from agricultural biomass with the epoxy resin. Flexural properties of activated carbons filled epoxy nano composites with 1 %, and 5 % filler loading were measured. In terms of flexural strength and modulus, a significant increment was observed with addition of 1 % vol and 5 % vol nano-activated carbon as compared to neat epoxy. The effect of activated carbon treated by two chemical agents (potassium hydroxide and phosphoric acid) on the flexural properties of epoxy nano composites were also investigated. Flexural strength of activated carbon-bamboo stem, activated carbon-oil palm, and activated carbon-coconut shell reinforced epoxy nano composites showed almost same value in case of 5 % potassium hydroxide activated carbon. Flexural strength of potassium hydroxide activated carbon-based epoxy nano composites was higher than phosphoric acid activated carbon. The flexural toughness of both the potassium hydroxide and phosphoric acid activated carbon reinforced composites range between 0.79 - 0.92 J. It attributed that developed activated carbon filled epoxy nano composites can be used in different applications. (author)

  4. Polyurethane/organo clay nano composite materials via in-situ polymerization

    International Nuclear Information System (INIS)

    Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

    2005-01-01

    Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

  5. Development of novel nano-composite membranes as introduction systems for mass spectrometers: Contrasting nano-composite membranes and conventional inlet systems

    Science.gov (United States)

    Miranda, Luis Diego

    This dissertation presents the development of novel nano-composite membranes as introduction systems for mass spectrometers. These nano-composite membranes incorporate anodic aluminum oxide (AAO) membranes as templates that can be used by themselves or modified by a variety of chemical deposition processes. Two types of nano-composite membranes are presented. The first nano-composite membrane has carbon deposited within the pores of an AAO membrane. The second nano-composite membrane is made by coating an AAO membrane with a thin polymer film. The following chapters describe the transmission properties these nano-composite membranes and compare them to conventional mass spectrometry introduction systems. The nano- composite membranes were finally coupled to the inlet system of an underwater mass spectrometer revealing their utility in field deployments.

  6. BACTERICIDE IMPACT OF POLYMER-STABILIZED MULTI-FUNCTIONAL NANO-COMPOSITES

    Directory of Open Access Journals (Sweden)

    Graskova I.A.

    2012-08-01

    containing selenium stabilized by various polymers. Nano-composites anti-microbe activity was studied on the investigated strain of potato ring rot. Nano-composites of elementary selenium (3.4% Se and Se with arabinogalactan acquired from SeO2 (1.23% Se were found to demonstrate anti-microbe effect increasing with the rise of selenium content. The work enumerates various conditions and time periods of cultivation and determination of the influence of the given water-soluble nano-composites on bacterial cells survivability.

  7. Comparison between properties of polyurethane nano composites prepared by two different methods

    International Nuclear Information System (INIS)

    Barmar, M.; Barikani, M.; Fereidoonnia, M.

    2009-01-01

    In this work, a thermoplastic polyurethane elastomer model based on polytetramethylene glycol. toluene diisocyanate and 1,4-butanediol was selected and synthesized. According to this model two types of polyurethane nano composites were prepared by in situ polymerization and melt intercalation procedures. The organo-modified nano clay was used in nano composites samples in 0.4 weight percent level. The prepared nano composites were studied by WAXD, tensile and thermal analysis. Thermal properties of the nano composites were higher than those of pure polyurethane elastomers. Nano composites prepared via melt intercalation method showed a lower tensile strength and hardness than those prepared through in situ polymerization method

  8. Relation Between Bitumen Content and Percentage Air Voids in Semi Dense Bituminous Concrete

    Science.gov (United States)

    Panda, R. P.; Das, Sudhanshu Sekhar; Sahoo, P. K.

    2018-06-01

    Hot mix asphalt (HMA) is a heterogeneous mix of aggregate, mineral filler, bitumen, additives and air voids. Researchers have indicated that the durability of the HMA is sensitive on the actual bitumen content and percentage air void. This paper aims at establishing the relationship between the bitumen content and the percentage air voids in Semi Dense Bituminous Concrete (SDBC) using Viscosity Grade-30 (VG-30) bitumen. Total 54 samples have been collected, for formulation and validation of relationship and observed that the percentage air voids increases with decrease in actual bitumen content and vice versa. A minor increase in percentage air voids beyond practice of designed air voids in Marshall Method of design is required for better performance, indicating a need for reducing the codal provision of minimum bitumen content for SDBC as specified in Specification for Road & Bridges (Fourth Revision) published by Indian Road Congress, 2001. The study shows a possibility of reducing designed minimum bitumen content from codal provision for SDBC by 0.2% of weight with VG-30 grade of Bitumen.

  9. Relation Between Bitumen Content and Percentage Air Voids in Semi Dense Bituminous Concrete

    Science.gov (United States)

    Panda, R. P.; Das, Sudhanshu Sekhar; Sahoo, P. K.

    2018-02-01

    Hot mix asphalt (HMA) is a heterogeneous mix of aggregate, mineral filler, bitumen, additives and air voids. Researchers have indicated that the durability of the HMA is sensitive on the actual bitumen content and percentage air void. This paper aims at establishing the relationship between the bitumen content and the percentage air voids in Semi Dense Bituminous Concrete (SDBC) using Viscosity Grade-30 (VG-30) bitumen. Total 54 samples have been collected, for formulation and validation of relationship and observed that the percentage air voids increases with decrease in actual bitumen content and vice versa. A minor increase in percentage air voids beyond practice of designed air voids in Marshall Method of design is required for better performance, indicating a need for reducing the codal provision of minimum bitumen content for SDBC as specified in Specification for Road & Bridges (Fourth Revision) published by Indian Road Congress, 2001. The study shows a possibility of reducing designed minimum bitumen content from codal provision for SDBC by 0.2% of weight with VG-30 grade of Bitumen.

  10. Studies on structural properties of clay magnesium ferrite nano composite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manpreet, E-mail: manpreetchem@pau.edu; Singh, Mandeep [Department of Chemistry, Punjab Agricultural University, Ludhiana-141004 (India); Jeet, Kiran, E-mail: kiranjeet@pau.edu; Kaur, Rajdeep [Electron Microscopy and Nanoscience Laboratory, Punjab Agricultural University, Ludhiana-141004 (India)

    2015-08-28

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  11. Action of colloidal silica films on different nano-composites

    Directory of Open Access Journals (Sweden)

    S. Abdalla

    Full Text Available Nano-composite films have been the subject of extensive work to develop the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nano-particles size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that form an insulating film between conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of 4 high pure amorphous polymer films: polymethylmethacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher break down performance is a character of polyimide PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer. Keywords: Dielectric break down, Polymers, Nano-composite, Colloidal silica

  12. Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

    Energy Technology Data Exchange (ETDEWEB)

    Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

    2016-08-15

    Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. The results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.

  13. CO oxidation on Alsbnd Au nano-composite systems

    Science.gov (United States)

    Rajesh, C.; Majumder, C.

    2018-03-01

    Using first principles method we report the CO oxidation behaviour of Alsbnd Au nano-composites in three different size ranges: Al6Au8, Al13Au42 and a periodic slab of Alsbnd Au(1 1 1) surface. The clusters prefer enclosed structures with alternating arrangement of Al and Au atoms, maximising Auδ-sbnd Alδ+ bonds. Charge distribution analysis suggests the charge transfer from Al to Au atoms, corroborated by the red shift in the density of states spectrum. Further, CO oxidation on these nano-composite systems was investigated through both Eley - Rideal and Langmuir Hinshelwood mechanism. While, these clusters interact with O2 non-dissociatively with an elongation of the Osbnd O bond, further interaction with CO led to formation of CO2 spontaneously. On contrary, the CO2 evolution by co-adsorption of O2 and CO molecules has a transition state barrier. On the basis of the results it is inferred that nano-composite material of Alsbnd Au shows significant promise toward effective oxidative catalysis.

  14. Poly (lactic acid organoclay nano composites for paper coating applications

    Directory of Open Access Journals (Sweden)

    Tatcha Sonjui

    2014-10-01

    Full Text Available Poly(lactic acid or PLA is a well-known biodegradable polymer derived from renewable resources such as corn strach, tapioca strach, and sugar cane. PLA is the most extensively utilized biodegradable polyester with potential to replace conventional petrochemical-based polymers. However, PLA has some drawbacks, such as brittleness and poor gas barrier properties. Nano composite polymers have experience and increasing interest due to their characteristics, especially in mechanical and thermal properties. The objectives of this research were to prepare PLA formulations using three different PLAs. The formulas giving high gloss coating film were selected to prepare nano composite film by incorporated with different amount of various types of organoclays. The physical properties of the PLA coating films were studied and it was found that the PLA 7000D with 0.1%w/w of Cloisite 30B provided decent viscosity for coating process. In addition, the nano composite coating films showed good physical properties such as high gloss, good adhesion, and good hardness. There is a possibility of using the obtained formulation as a paper coating film.

  15. Antimicrobial Properties of Chitosan-Alumina/f-MWCNT Nano composites

    International Nuclear Information System (INIS)

    Masheane, M.; Nthunya, L.; Malinga, S.; Masheane, M.; Nthunya, L.; Nxumalo, E.; Mhlanga, S.; Barnard, T.

    2016-01-01

    Antimicrobial chitosan-alumina/functionalized-multi walled carbon nano tube (f-MWCNT) nano composites were prepared by a simple phase inversion method. Scanning electron microscopy (SEM) analyses showed the change in the internal morphology of the composites and energy dispersive spectroscopy (EDS) confirmed the presence of alumina and f-MWCNTs in the chitosan polymer matrix. Fourier transform infrared (FTIR) spectroscopy showed the appearance of new functional groups from both alumina and f-MWCNTs, and thermogravimetric analysis (TGA) revealed that the addition of alumina and f-MWCNTs improved the thermal stability of the chitosan polymer. The presence of alumina and f-MWCNTs in the polymer matrix was found to improve the thermal stability and reduced the solubility of chitosan polymer. The prepared chitosan-alumina/f-MWCNT nano composites showed inhibition of twelve strains of bacterial strains that were tested. Thus, the nano composites show a potential for use as a biocides in water treatment for the removal of bacteria at different environmental conditions.

  16. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite; Propriedades funcionais de nanocompositos extrusados de amido de mandioca, alcool polivinilico e montmorilonita

    Energy Technology Data Exchange (ETDEWEB)

    Debiagi, Flavia; Mali, Suzana [Departamento de Bioquimica e Biotecnologia, Universidade Estadual de Londrina, PR (Brazil)

    2011-07-01

    The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

  17. Tailored sPP/Silica Nano composite for Eco friendly Insulation of Extruded HVDC Cable

    International Nuclear Information System (INIS)

    Dang, B.; He, J.; Hu, J.; Zhou, Y.

    2015-01-01

    Cross-linked polyethylene (XLPE) is a thermosetting material that cannot be recycled at the end of its lifetime. This study investigated the potential of syndiotactic polypropylene (sPP)/silica as an eco friendly extruded insulation system for HVDC cables. We investigated the morphology, Fourier transform infrared, and thermal, thermomechanical, and electrical behaviors of sPP modified with 0.5-3% nano silica. We found that the silica/sPP nano composite without cross-linking offered a suitable mechanical modulus at room temperature and sufficient intensity at high temperatures, and adding nano silica modified by a silane coupling agent to the sPP resulted in significant DC resistivity and space charge improvement. The optimal nano silica content in the sPP was determined by balancing the mechanical and thermomechanical characteristics and the DC resistivity. The sPP/silica nano composite reported here shows great potential as a candidate insulation material for future eco friendly extruded HVDC cables.

  18. Preparation of organophilic clays and polypropylene nano composites

    International Nuclear Information System (INIS)

    Lima, Martha Fogliato S.; Nascimento, Vinicius G. do; Lenz, Denise M.; Schenato, Flavia

    2011-01-01

    Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

  19. Adaptive Backoff Algorithm for Contention Window for Dense IEEE 802.11 WLANs

    Directory of Open Access Journals (Sweden)

    Ikram Syed

    2016-01-01

    Full Text Available The performance improvement in IEEE 802.11 WLANs in widely fluctuating network loads is a challenging task. To improve the performance in this saturated state, we develop an adaptive backoff algorithm that maximizes the system throughput, reduces the collision probability, and maintains a high fairness for the IEEE 802.11 DCF under dense network conditions. In this paper, we present two main advantages of the proposed ABA-CW algorithm. First, it estimates the number of active stations and then calculates an optimal contention window based on the active station number. Each station calculates the channel state probabilities by observing the channel for the total backoff period. Based on these channel states probabilities, each station can estimate the number of active stations in the network, after which it calculates the optimal CW utilizing the estimated active number of stations. To evaluate the proposed mechanism, we derive an analytical model to determine the network performance. From our results, the proposed ABA-CW mechanism achieved better system performance compared to fixed-CW (BEB, EIED, LILD, and SETL and adaptive-CW (AMOCW, Idle Sense mechanisms. The simulation results confirmed the outstanding performance of the proposed mechanism in that it led to a lower collision probability, higher throughput, and high fairness.

  20. Microstructure and Mechanical Properties of Multiphase Strengthened Al/Si/Al_2O_3/SiO_2/MWCNTs Nano composites Sintered by In Situ Vacuum Hot Pressing

    International Nuclear Information System (INIS)

    Li, J.; Jiang, X.; Zhu, D.; Zhu, M.; Shao, Z.; Johnson, S.; Luo, Z.

    2015-01-01

    Eutectic Al/Si binary alloy is technically one of the most important Al casting alloys due to its high corrosion resistance, evident shrinkage reduction, low thermal expansion coefficient, high fluidity, and good weldability. In this work, multi phased Al/Si matrix nano composites reinforced with Al_2O_3 and multi walled carbon nano tubes (MWCNTs) have been sintered by an in situ vacuum hot-pressing method. The alumina Al_2O_3 nanoparticles were introduced by an in situ reaction of Al with SiO_2. Microstructure and mechanical properties of the sintered Al/Si/Al_2O_3/SiO_2/MWCNTs nano composites with different alumina contents were investigated. The mechanical properties were determined by micro-Vickers hardness and compressive and shear strength tests. The results demonstrated that in situ alumina and MWCNTs had impacts on microstructure and mechanical properties of the nano composites. Based on the mechanical properties and microstructure of the nano composites, strengthening and fracture mechanisms by multiple reinforcements were analyzed

  1. Eco-nano composite films containing copper as potential antimicrobial active packaging

    Energy Technology Data Exchange (ETDEWEB)

    Bruna, Julio E.; Gonzalez, Valeska; Rodriguez, Francisco; Guarda, Abel; Galotto, Maria Jose, E-mail: julio.bruna@usach.cl [Center for the Development of Nanoscience and Nanotechnology, Packaging Laboratory, University of Santiago de Chile. Santiago (Chile)

    2011-07-01

    The antimicrobial efficiency of Cellulose Acetate/MMTCu and Chitosan/MMTCu nano composites against Escherichia Coli 0157:H7 n/t has been studied in the present work. The MMT modified with copper were obtained using cation interchange in solution and the nano composites films were prepared using casting solution technique, being the biodegradable polymer (Cellulose Acetate or Chitosan) the main component and the montmorillonite modified with copper, the minority component. Characterization of MMTCu and the nano composites (CA/MMTCu and Ch/MMTCu), were carried out using XRD, AA, TGA, DSC and microbiological analysis. The nano composites showed to be more stable at higher temperature, resulting from the incorporation of MMTCu into the polymer. On the other hand, the results indicated that the antibacterial effect of nano composite increased with the proportion of MMTCu added. (author)

  2. Eco-nano composite films containing copper as potential antimicrobial active packaging

    International Nuclear Information System (INIS)

    Bruna, Julio E.; Gonzalez, Valeska; Rodriguez, Francisco; Guarda, Abel; Galotto, Maria Jose

    2011-01-01

    The antimicrobial efficiency of Cellulose Acetate/MMTCu and Chitosan/MMTCu nano composites against Escherichia Coli 0157:H7 n/t has been studied in the present work. The MMT modified with copper were obtained using cation interchange in solution and the nano composites films were prepared using casting solution technique, being the biodegradable polymer (Cellulose Acetate or Chitosan) the main component and the montmorillonite modified with copper, the minority component. Characterization of MMTCu and the nano composites (CA/MMTCu and Ch/MMTCu), were carried out using XRD, AA, TGA, DSC and microbiological analysis. The nano composites showed to be more stable at higher temperature, resulting from the incorporation of MMTCu into the polymer. On the other hand, the results indicated that the antibacterial effect of nano composite increased with the proportion of MMTCu added. (author)

  3. Radiation effect on characterization and physical properties of polymer nano composites

    International Nuclear Information System (INIS)

    Tawfik, E.K.M.

    2013-01-01

    Polymeric materials are of interest in scientific and technological research, because they can be tailored to meet specific requirement for a verity of applications, this is mainly due to their light weight, good mechanical strength, and optical properties.From which, Poly Vinyl Alcohol (PVA) is one of the most important polymeric materials, because it has many applications in industry and is of relatively low cost in manufacture. It is well documented that electrical and optical properties of polymers can be improved to a desired limit through suitable doping. In this concern, and since Ag + is a fast conducting ion in a number of crystalline and amorphous materials, its incorporation within a polymeric system may be expected to enhance its electrical and optical properties. In the present study the PVA/Ag nano composite with different contents of inorganic phase of (2, 3, 4, 5, 6, 7, and 8) wt % were prepared by reduction of Ag + ions in PVA solution using gamma irradiation with different dose of (15, 25, 50, 75, 100) kGy. The Ag particle size was found to be around 14.0 nm based on the UV-Vis spectroscopy and Dynamic Light Scattering (DLS) measurements. Also, the structural studies of the synthesized PVA/Ag nano composites have been carried out through FTIR, and XRD studies. Further, the dependence of the optical and electrical properties of PVA on the concentration of the embedded nano-Ag was reported. As well, the effects of γ- irradiation have been studied applying UV-Vis spectroscopy and electrical characteristics measurements, respectively.

  4. Effect of gamma radiation and accelerated aging on the mechanical and thermal behavior of HDPE/HA nano-composites for bone tissue regeneration.

    Science.gov (United States)

    Alothman, Othman Y; Almajhdi, Fahad N; Fouad, H

    2013-09-24

    The replacement of hard tissues demands biocompatible and sometimes bioactive materials with properties similar to those of bone. Nano-composites made of biocompatible polymers and bioactive inorganic nano particles such as HDPE/HA have attracted attention as permanent bone substitutes due to their excellent mechanical properties and biocompatibility. The HDPE/HA nano-composite is prepared using melt blending at different HA loading ratios. For evaluation of the degradation by radiation, gamma rays of 35 kGy, and 70 kGy were used to irradiate the samples at room temperature in vacuum. The effects of accelerated ageing after gamma irradiation on morphological, mechanical and thermal properties of HDPE/HA nano-composites were measured. In Vitro test results showed that the HDPE and all HDPE/HA nano-composites do not exhibit any cytotoxicity to WISH cell line. The results also indicated that the tensile properties of HDPE/HA nano-composite increased with increasing the HA content except fracture strain decreased. The dynamic mechanical analysis (DMA) results showed that the storage and loss moduli increased with increasing the HA ratio and the testing frequency. Finally, it is remarked that all properties of HDPE/HA is dependent on the irradiation dose and accelerated aging. Based on the experimental results, it is found that the addition of 10%, 20% and 30% HA increases the HDPE stiffness by 23%, 44 and 59% respectively. At the same time, the G' increased from 2.25E11 MPa for neat HDPE to 4.7E11 MPa when 30% HA was added to the polymer matrix. Also, significant improvements in these properties have been observed due to irradiation. Finally, the overall properties of HDPE and its nano-composite properties significantly decreased due to aging and should be taken into consideration in the design of bone substitutes. It is attributed that the developed HDPE/HA nano-composites could be a good alternative material for bone tissue regeneration due to their acceptable

  5. Performance enhancement of quantum dot-sensitized solar cells based on polymer nano-composite catalyst

    International Nuclear Information System (INIS)

    Seo, Hyunwoong; Gopi, Chandu V.V.M.; Kim, Hee-Je; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2017-01-01

    Highlights: •We studied polymer nano-composite containing TiO 2 nano-particles as a catalyst. •Polymer nano-composite was applied for quantum dot-sensitized solar cells. •Polymer nano-composite catalyst was considerably improved with TiO 2 nano-particles. •Polymer nano-composite showed higher photovoltaic performance than conventional Au. -- Abstract: Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and TiO 2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V OC , 12.24 mA cm −2 of J SC , 0.57 of FF, and 3.87% of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75%).

  6. Gamma radiation effects on nano composites of Ag nanoparticles in Zn O matrices

    International Nuclear Information System (INIS)

    Villasenor C, L. S.

    2015-01-01

    The study of gamma radiation effects in nano composites of silver nanoparticles in a Zn O matrix has been performed in this work. First, silver nanoparticles (AgNPs) were synthesized by colloidal methods, with two different mean average sizes, 48 nm and 24 nm respectively. These nanoparticles were characterized by transmission electron microscopy (Tem) and UV-Vis spectroscopy (UV-Vis). Then, with the synthesized AgNPs, nano composites in a matrix of Zn O were prepared. The first nano composite was prepared with the 48 nm AgNPs at 9.5 weight % of silver (Ag) and the second nano composite with the 24 nm nanoparticles at 1.0 weight % of Ag. Both nano composites were analyzed by scanning electron microscopy (Sem). The formation of the Zn O phase in the nano composite was corroborated through X-ray diffraction analysis. It was observed that the presence of AgNPs during the formation of the AgNPs/Zn O nano composite modified the size and morphology of the structures obtained compared to those of the pure Zn O without nanoparticles, however both exhibit a radial structure. Then, the nano composite at 9.5 weight % of Ag was irradiated with gamma rays at doses of 1, 20 and 50 kGy. Samples were analyzed by Sem and the Bet technique, before and after being irradiated, in order to determine the effect of gamma radiation in the morphology, porosity and surface area of the studied material. Even when there are changes in porosity and Surface area, this difference is not very significant for some applications, however it will have to be considered during the design of a specific application of the nano composites. On the other hand, no morphology modifications were identified on the samples irradiated at the studied doses, with the electron microscopy techniques used. (Author)

  7. Mechanical and microstructure of reinforced hydroxyapatite/calcium silicate nano-composites materials

    International Nuclear Information System (INIS)

    Beheri, Hanan H.; Mohamed, Khaled R.; El-Bassyouni, Gehan T.

    2013-01-01

    Highlights: ► Nano sized of HA and CS powders were prepared. ► Mechanical of HACS composites enhanced with content of CS. ► The apatite formation onto the composites is proved. -- Abstract: In this study, the nano sized hydroxyapatite (HA) and calcium silicate (CS) powders prepared by both chemical precipitation and sol–gel methods respectively. Biphasic nano-composites materials containing different ratios of HA and CS were fabricated and assessed using X-ray diffraction (XRD), Fourier transmission infrared reflectance (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The effect of variation of ratios between HA and CS on mechanical properties, microstructure and in vitro study was studied. The results proved that the mechanical properties were enhanced with increasing the CS ratio in the composite. In vitro study proved the formation and nucleation of apatite onto composites surfaces which contain low content of CS after one week of immersion. Finally, it is concluded that the HACS composites containing high HA content at the expense of CS content will be promising for bone substitute’s applications, especially in load bearing sites.

  8. Study of thermal properties and the dispersion state of nano composites epoxy/clay

    International Nuclear Information System (INIS)

    Paz, Juliana D.; Bertholdi, Jonas; Toledo, Tais C.; Folgueras, Marilena V.; Pezzin, Sergio H.; Coelho, Luiz A.F.

    2011-01-01

    This work investigates an exfoliation/intercalation of nano clays in an epoxy resin by means of x-rays diffraction, scanning electronic microscopy, thermal gravimetric analysis and dilatometric analysis. A comparison of two techniques for preparing nano composites is addressed: mechanical stirring and sonication. X-rays analysis showed that an exfoliation/intercalation is occurring in some samples. TG analysis indicated and increase in thermal stability of the nano composites compared to the neat resin. Finally, dilatometric analysis indicates and increase in Tg for nano composites compared to the neat resin. (author)

  9. Influence of Ionic Liquid Content on Properties of Dense Polymer Membranes

    Czech Academy of Sciences Publication Activity Database

    Kohoutová, Marie; Sikora, Antonín; Hovorka, Š.; Randová, A.; Schauer, Jan; Tišma, J.; Setničková, Kateřina; Petričkovič, Roman; Guernik, S.; Greenspoon, N.; Izák, Pavel

    2009-01-01

    Roč. 45, č. 3 (2009), s. 813-819 ISSN 0014-3057 R&D Projects: GA ČR GA104/08/0600; GA ČR GA203/08/0465 Grant - others:MERG(XE) CT/2006/44737 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40500505 Keywords : dense polymer membranes * biofuel * fermentation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.310, year: 2009

  10. Investigation on Nano composite Membrane of Multi walled Carbon Nano tube Reinforced Polycarbonate Blend for Gas Separation

    International Nuclear Information System (INIS)

    Kausar, A.

    2016-01-01

    Carbon nano tube has been explored as a nano filler in high performance polymeric membrane for gas separation. In this regard, nano composite membrane of polycarbonate (PC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVFHFP), and multi walled carbon nano tube (MWCNT) was fabricated via phase inversion technique. Poly (ethylene glycol) (PEG) was employed for the compatibilization of the blend system. Two series of PC/PVFHFP/PEG were developed using purified P-MWCNT and acid functional A-MWCNT nano filler. Scanning and transmission electron micrographs have shown fine nano tube dispersion and wetting by matrix, compared with the purified system. Tensile strength and Young s modulus of PC/PVFHFP/PEG/MWCNT-A 1-5 were found to be in the range of 63.6-72.5 MPa and 110.6-122.1 MPa, respectively. The nano composite revealed 51% increase in Young s modulus and 28% increase in tensile stress relative to the pristine blend. The A-MWCNT was also effective in enhancing the perm selectivity αCO 2 /N 2 (31.2-39.9) of nano composite membrane relative to the blend membrane (21.6). The permeability ρCO 2 of blend was 125.6 barrer; however, the functional series had enhancedρCO 2 values ranging from 142.8 to 186.6 barrer. Moreover, A-MWCNT loading improved the gas diffusivity of PC/PVFHFP/PEG/MWCNT-A 1-5; however, filler content did not significantly influence the CO 2 and N 2 solubility.

  11. Correlation between nanostructural and electrical properties of barium titanate-based glass-ceramic nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Al-Assiri, M.S., E-mail: msassiri@kku.edu.sa [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); El-Desoky, M.M., E-mail: mmdesoky@gmail.com [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt)

    2011-09-08

    Highlights: > Glasses have been transformed into nanomaterials by annealing at crystallization temperature. > Glass-ceramic nano-composites are important because of their new physical. > Grain sizes are the most significant structural parameter in electronic nanocrystalline phases. > These phases are very high electrical conductivity. > Hence, glass-ceramic nanocrystals are expected to be used, as gas sensors. - Abstract: Glasses in the system BaTiO{sub 3}-V{sub 2}O{sub 5}-Bi{sub 2}O{sub 3} have been transformed into glass-ceramic nano-composites by annealing at crystallization temperature T{sub cr} determined from DSC thermograms. After annealing they consist of small crystallites embedded in glassy matrix. The crystallization temperature T{sub cr} increases with increasing BaTiO{sub 3} content. XRD and TEM of the glass-ceramic nano-composites show that nanocrystals were embedded in the glassy matrix with an average grain size of 25 nm. The resulting materials exhibit much higher electrical conductivity than the initial glasses. It was postulated that the major role in the conductivity enhancement of these nanomaterials is played by the developed interfacial regions between crystalline and amorphous phases, in which the concentration of V{sup 4+}-V{sup 5+} pairs responsible for electron hopping, has higher than values that inside the glassy matrix. The experimental results were discussed in terms of a model proposed in this work and based on a 'core-shell' concept. From the best fits, reasonable values of various small polaron hopping (SPH) parameters were obtained. The conduction was attributed to non-adiabatic hopping of small polaron.

  12. PREFACE: International Conference on Structural Nano Composites (NANOSTRUC 2012)

    Science.gov (United States)

    Njuguna, James

    2012-09-01

    Dear Colleagues It is a great pleasure to welcome you to NanoStruc2012 at Cranfield University. The purpose of the 2012 International Conference on Structural Nano Composites (NanoStruc2012) is to promote activities in various areas of materials and structures by providing a forum for exchange of ideas, presentation of technical achievements and discussion of future directions. NanoStruc brings together an international community of experts to discuss the state-of-the-art, new research results, perspectives of future developments, and innovative applications relevant to structural materials, engineering structures, nanocomposites, modelling and simulations, and their related application areas. The conference is split in 7 panel sessions, Metallic Nanocomposites and Coatings, Silica based Nanocomposites, safty of Nanomaterials, Carboin based Nanocomposites, Multscale Modelling, Bio materials and Application of Nanomaterials. All accepted Papers will be published in the IOP Conference Series: Materials Science and Engineering (MSE), and included in the NanoStruc online digital library. The abstracts will be indexed in Scopus, Compedex, Inspec, INIS (International Nuclear Information System), Chemical Abstracts, NASA Astrophysics Data System and Polymer Library. Before ending this message, I would like to acknowledge the hard work, professional skills and efficiency of the team which ensured the general organisation. As a conclusion, I would like to Welcome you to the Nanostruc2012 and wish you a stimulating Conference and a wonderful time. On behalf of the scientific committee, Signature James Njuguna Conference Chair The PDF of this preface also contains committee listings and associates logos.

  13. Effect of organo clay addition on thermal properties of poly lactide/ polycaprolactone (PLA/ PCL) nano composites

    International Nuclear Information System (INIS)

    Siti Zulaiha Hairaldin; Wan Md Zin Wan Yunus; Norazoma Ibrahim

    2010-01-01

    In this study, melt blending technique was applied to prepare poly lactide/polycaprolactone (PLA/ PCL) nano composites with various blends. Montmorillonite (MMT) was used as an addition to the matrix. In this study, melt blending technique was applied to prepare poly lactide/polycaprolactone (PLA/ PCL) nano composites. Montmorillonite (MMT) was used as an addition to the matrix with various percentages. The other one is modified clay prepared by modifying the nature of montmorillonite with octadecylamine (ODA) to improve the characteristic of PLA/ PCL blends. X-ray diffraction (XRD) results indicated intercalation of the PLA/ PCL into silicate nano size interlayers galleries of the nano composites. The presence of modified clays in nano composite was confirmed by FTIR spectrum. TGA and DTG results show addition of MMT and modified clay ODA-MMT improved the thermal stability of the PLA/ PCL blends. (author)

  14. Development of nano-composite membranes to improve alkaline fuel cell performance

    CSIR Research Space (South Africa)

    Nonjola, P

    2011-09-01

    Full Text Available The work presented here describes modification of commercially available polysulfone (PSU) as well as the formation of nano-composite membrane i.e. TiO2 nano particles incorporated into anion exchange polymer matrix....

  15. Nuclear magnetic resonance applied to the study of polymeric nano composites

    International Nuclear Information System (INIS)

    Tavares, Maria Ines Bruno

    2011-01-01

    Polymers and nanoparticles based nano composites were prepared by intercalation by solution. The obtained nano composites were characterized mainly by the nuclear magnetic spectroscopy (NMR), applying the analysis of carbon-13 (polymeric matrix), silicon-29 (nanoparticle), and by determination of spin-lattice relaxation of the hydrogen nucleus (T 1 H) (polymeric matrix). The NMR have presented a promising technique in the characterization of the nano charge dispersion in the studied polymeric matrixes.

  16. Some Fundamental Aspects of Mechanics of Nano composite Materials and Structural Members

    International Nuclear Information System (INIS)

    Guz, A.N.; Rushchitsky, J.J.

    2013-01-01

    This paper is devoted to formulation and analysis of fundamental aspects of mechanics of nano composite materials and structural members. These aspects most likely do not exhaust all of the possible fundamental characteristics of mechanics of nano composite materials and structural members, but, nevertheless, they permit to form the skeleton of direction of mechanics in hand. The proposed nine aspects are described and commented briefly.

  17. Optical Properties and Surface Morphology of Nano-composite PMMA: TiO2 Thin Films

    International Nuclear Information System (INIS)

    Lyly Nyl Ismail; Ahmad Fairoz Aziz; Habibah Zulkefle

    2011-01-01

    There are two nano-composite PMMA: TiO 2 solutions were prepared in this research. First solution is nano-composite PMMA commercially available TiO 2 nanopowder and the second solution is nano-composite PMMA with self-prepared TiO 2 powder. The self-prepared TiO 2 powder is obtained by preparing the TiO 2 sol-gel. Solvo thermal method were used to dry the TiO 2 sol-gel and obtained TiO 2 crystal. Ball millers were used to grind the TiO 2 crystal in order to obtained nano sized powder. Triton-X was used as surfactant to stabilizer the composite between PMMA: TiO 2 . Besides comparing the nano-composite solution, we also studied the effect of the thin films thickness on the optical properties and surface morphology of the thin films. The thin films were deposited by sol-gel spin coating method on glass substrates. The optical properties and surface characterization were measured with UV-VIS spectrometer equipment and atomic force microscopy (AFM). The result showed that nano-composite PMMA with self prepared TiO 2 give high optical transparency than nano-composite PMMA with commercially available TiO 2 nano powder. The results also indicate as the thickness is increased the optical transparency are decreased. Both AFM images showed that the agglomerations of TiO 2 particles are occurred on the thin films and the surface roughness is increased when the thickness is increased. High agglomeration particles exist in the AFM images for nano-composite PMMA: TiO 2 with TiO 2 nano powder compare to the other nano-composite solution. (author)

  18. Development and evaluation of fast forming nano-composite hydrogel for ocular delivery of diclofenac.

    Science.gov (United States)

    Li, Xingyi; Zhang, Zhaoliang; Chen, Hao

    2013-05-01

    In this paper, a fast forming nano-composite hydrogel was developed for potential application in ocular drug delivery. The optical transmission (OT) as well as rheological properties of nano-composite hydrogel was characterized. The developed nano-composite hydrogel given a high diclofenac micelles loading and provided a sustained release manner of diclofenac within 6h. The developed nano-composite hydrogel formulation was administrated into the eye as flowable solution, quickly forming a hydrogel that is able to resist of the blinking and flushing of tear, yet resulting in the prolonged residence time of pre-corneal. In vivo eye irritation test suggested that the developed nano-composite hydrogel was none-eye irritation might be suitable for various ocular applications. In vivo pharmacokinetic study indicated that the developed nano-composite hydrogel could significantly increase the bioavailability of diclofenac and maintain the concentration of diclofenac in aqueous humor above MEC at least 24h after administration as compared with that of the commercial diclofenac sodium eye drops, which might be able to reduce the frequency of administration for patients. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. LDPE/HDPE/Clay Nano composites: Effects of Compatibilizer on the Structure and Dielectric Response

    International Nuclear Information System (INIS)

    David, Z.E.; Ngo, A.D.

    2013-01-01

    PE/clay nano composites were prepared by mixing a commercially available premixed polyethylene/O-MMT master batch into a polyethylene blend matrix containing 80 wt% low-density polyethylene and 20 wt% high-density polyethylene with and without anhydride modified polyethylene (PE-MA) as the compatibilizer using a corotating twin-screw extruder. In this study, the effect of nano clay and compatibilizer on the structure and dielectric response of PE/clay nano composites has been investigated. The microstructure of PE/clay nano composites was characterized using wide-angle X-ray diffraction (WAXD) and a scanning electron microscope (SEM). Thermal properties were examined using differential scanning calorimetry (DSC). The dielectric response of neat PE was compared with that of PE/clay nano composite with and without the compatibilizer. The XRD and SEM results showed that the PE/O-MMT nano composite with the PE-MA compatibilizer was better dispersed. In the nano composite materials, two relaxation modes are detected in the dielectric losses. The first relaxation is due to a Maxwell-Wagner-Sillars interfacial polarization, and the second relaxation can be related to dipolar polarization. A relationship between the degree of dispersion and the relaxation rate f m ax of Maxwell-Wagner-Sillars was found and discussed.

  20. Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials.

    Science.gov (United States)

    Mohamed, Khaled R; Beherei, Hanan H; El Bassyouni, Gehan T; El Mahallawy, Nahed

    2013-10-01

    In the current study, the semiconducting metal oxides such as nano-ZnO and SiO2 powders were prepared via sol-gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO2 were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO2 or SiO2/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Nano-Composite Foam Sensor System in Football Helmets.

    Science.gov (United States)

    Merrell, A Jake; Christensen, William F; Seeley, Matthew K; Bowden, Anton E; Fullwood, David T

    2017-12-01

    American football has both the highest rate of concussion incidences as well as the highest number of concussions of all contact sports due to both the number of athletes and nature of the sport. Recent research has linked concussions with long term health complications such as chronic traumatic encephalopathy and early onset Alzheimer's. Understanding the mechanical characteristics of concussive impacts is critical to help protect athletes from these debilitating diseases and is now possible using helmet-based sensor systems. To date, real time on-field measurement of head impacts has been almost exclusively measured by devices that rely on accelerometers or gyroscopes attached to the player's helmet, or embedded in a mouth guard. These systems monitor motion of the head or helmet, but do not directly measure impact energy. This paper evaluates the accuracy of a novel, multifunctional foam-based sensor that replaces a portion of the helmet foam to measure impact. All modified helmets were tested using a National Operating Committee Standards for Athletic Equipment-style drop tower with a total of 24 drop tests (4 locations with 6 impact energies). The impacts were evaluated using a headform, instrumented with a tri-axial accelerometer, mounted to a Hybrid III neck assembly. The resultant accelerations were evaluated for both the peak acceleration and the severity indices. These data were then compared to the voltage response from multiple Nano Composite Foam sensors located throughout the helmet. The foam sensor system proved to be accurate in measuring both the HIC and Gadd severity index, as well as peak acceleration while also providing additional details that were previously difficult to obtain, such as impact energy.

  2. Tribological behavior of Al-WC nano-composites fabricated by ultrasonic cavitation assisted stir-cast method

    Science.gov (United States)

    Pal, Arpan; Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

    2018-03-01

    In the present study, the effects of WC nano-particles content on the microstructure, hardness, wear, and friction behavior of aluminum matrix composites are investigated. Al-WC nano composites with varying wt% of WC (0, 1, 1.5, and 2) are fabricated using ultrasonic cavitation assisted stir-cast method. The microstructure of the nano-composite samples is analyzed using optical microscopy and scanning electron microscopy. Elemental composition is determined by energy dispersive x-ray analysis. Vicker’s microhardness test is performed in different locations on the composite sample surface with a load of 50 gf and 10s dwell time. Wear and friction of the composites under dry sliding is studied using a pin-on-disk tribotester for varying normal load (10–40 N) and sliding speed (0.1–0.4 m/s). Uniform distribution of nano-WC is observed over composite surface without noticeable clustering. Reinforcement of nano-WC particles improves wear resistance and frictional behavior of the composite. Hardness is seen to increase with increase in wt% of nano-particles. Wear behavior of composites depends on formation of layers over the surface mixed with oxidized debris and counter-face particles. Wear mechanism changes from adhesion to abrasion with increase in wt% of hard nano particles.

  3. Study of Ion Transport Behaviour in (PVA-NH4I):SIO2 Nano Composite Polymer Electrolyte

    Science.gov (United States)

    Tripathi, Mridula; Trivedi, Shivangi; Upadhyay, Ruby; Singh, Markandey; Pandey, N. D.; Pandey, Kamlesh

    2013-07-01

    Development and characterization of Poly vinyl alcohol (PVA) based nano composite polymer electrolytes comprising of (PVA-NH4I):SiO2 is reported. Sol-gel derived silica powder of nano dimension has been used as ceramic filler for development of nano composite electrolyte. Formation of nano composites, change in the structural and microscopic properties of the system have been investigated by X-ray differaction, SEM and conductivity.

  4. A comparison study of polymer/cobalt ferrite nano-composites synthesized by mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Sedigheh Rashidi

    2015-12-01

    Full Text Available In this research, the effect of different biopolymers such as polyethylene glycol (PEG and polyvinylalcohol (PVA on synthesis and characterization of polymer/cobalt ferrite (CF nano-composites bymechanical alloying method has been systematically investigated. The structural, morphological andmagnetic properties changes during mechanical milling were investigated by X-ray diffraction (XRD,Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM, fieldemission scanning electron microscopy (FESEM, and vibrating sample magnetometer techniques(VSM, respectively. The polymeric cobalt ferrite nano-composites were obtained by employing atwo-step procedure: the cobalt ferrite of 20 nm mean particle size was first synthesized by mechanicalalloying route and then was embedded in PEG or PVA biopolymer matrix by milling process. Theresults revealed that PEG melted due to the local temperature raise during milling. Despite thisphenomenon, cobalt ferrite nano-particles were entirely embedded in PEG matrix. It seems, PAV is anappropriate candidate for producing nano-composite samples due to its high melting point. InPVA/CF nano-composites, the mean crystallite size and milling induced strain decreased to 13 nm and0.48, respectively. Moreover, milling process resulted in well distribution of CF in PVA matrix eventhough the mean particle size of cobalt ferrite has not been significantly affecetd. FTIR resultconfirmed the attachment of PVA to the surface of nano-particles. Magnetic properties evaluationshowed that saturation magnetization and coercivity values decreased in nano-composite samplecomparing the pure cobalt ferrite.

  5. Fullerene and dendrimer based nano-composite gas separation membranes

    NARCIS (Netherlands)

    Sterescu, D.M.

    2007-01-01

    This thesis describes the development of new materials for membrane based gas separation processes. Long-term stable, loosely packed (high free volume) amorphous polymer films were prepared by introduction of super-molecular pendant groups, which possess hardsphere properties to avoid dense

  6. Chemically designed Pt/PPy nano-composite for effective LPG gas sensor.

    Science.gov (United States)

    Gaikwad, Namrata; Bhanoth, Sreenu; More, Priyesh V; Jain, G H; Khanna, P K

    2014-03-07

    Simultaneous in situ reduction of hexachloroplatinic acid by the amine group in the pyrrole monomer and oxidation of pyrrole to form polypyrrole (PPy) was examined. The reactions were performed at various temperatures to understand the degree of reduction of platinum precursor as well as doping of polypyrrole with Pt(II) chloro-complex. Spectroscopic images revealed different morphologies for the Pt/PPy nano-composite prepared at various temperatures. The as-prepared Pt/PPy nano-composite samples were tested for their ability to sense liquefied petroleum gas (LPG) which resulted in excellent sensing at relatively low temperature. The porous nature and ohmic contact between the PPy and platinum nanoparticles makes the as-prepared Pt/PPy nano-composite highly useful for sensors as well as electronic applications.

  7. Evaluation of the acquirement of nano composites of polypropylene and a bentonite organophilized by different methodologies

    International Nuclear Information System (INIS)

    Paiva, Lucilene B. de; Morales, Ana R.; Branciforti, Marcia C.; Bretas, Rosario E.S.

    2009-01-01

    This work describes the organophilization of an argentinean sodium bentonite with a quaternary ammo nium salt, by two methodologies: cation exchange in aqueous dispersion and intercalation in semi-solid medium. The modified samples were used in the preparation of nano composites, with polypropylene as a matrix and polypropylene-graft-maleic anhydride as a coupling agent, through melt intercalation by using a twin-screw micro extruder. The organophilic bentonites were characterized by the swelling capacity test in water and in xylene and by X-ray diffraction, and the nano composites were characterized by X-ray diffraction and transmission electronic microscopy. The results showed that were obtained nano composites with structures partially intercalated and exfoliated. (author)

  8. Optical properties study of nano-composite filled D shape photonic crystal fibre

    Directory of Open Access Journals (Sweden)

    R. Udaiyakumar

    2018-06-01

    Full Text Available With the nano-composite materials gaining momentum in the optical field, a new nano-composite filled D shape Photonic Crystal Fiber (PCF is designed and the various optical properties are investigated with help of Finite Element Method. In the proposed structure the D-shape PCF is made up of silica with embedded silver nanoparticles and air holes are distributed along the fibre. The designed fibre shows various optical properties such as dispersion, birefringence, beat length and loss with respect to wavelength and compared with different filling factor like 0.1, 0.3 and 0.5. From our estimation and comparative analysis, it has been proved that the fibre loss has been decreased with increasing filling factor. Further this also showed flat dispersion at maximum filling factor. Keywords: Nanoparticles, Nano-composite, Dispersion, Birefringence, Beat length

  9. Microstructure and mechanical properties of aluminum–fly ash nano composites made by ultrasonic method

    International Nuclear Information System (INIS)

    Narasimha Murthy, I.; Venkata Rao, D.; Babu Rao, J.

    2012-01-01

    Highlights: ► Nano structured fly ash has been produced by 30 h milling time. ► Al–fly ash nano composites were produced by ultrasonic cavitation route. ► A homogeneous distribution of nano fly ash particles was observed in the matrix. ► No additional contamination in the nano composites from the atmosphere. ► Presence of nano fly ash leads to improvement in the strength of the composites. -- Abstract: In this paper an attempt has been made to modify the micro sized fly ash into nano structured fly ash using high energy ball mill. Ball milling was carried out for the total duration of 30 h. The sample was taken out after every 5 h of milling for characterizing. The nano structured fly ash was characterized for its crystallite size and lattice strain by using X-ray diffractometer. It was found that a steady decrease in the crystallite size and increased lattice strain was observed with milling time; the crystallite size at 30 h milling time was found to be 23 nm. The fresh fly ash particles are mostly spherical in shape; whereas the shape of the 30 h milled fly ash particles is irregular and the surface morphology is rough. Al–fly ash nano composites were produced by ultrasonic cavitation route successfully. Scanning electron microscopy images of nano composites reveal a homogeneous distribution of the nano fly ash particles in the AA 2024 matrix. Energy dispersive spectroscopy analysis of nano composites reveals that the fabricated nano composite did not contain any additional contamination from the atmosphere. As the amount of nano fly ash is increasing the hardness of the composite also increasing. The nano fly ash addition leads to improvement in the compression strength of the composites.

  10. Fabrication and mechanical evaluation of hydroxyapatite/oxide nano-composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Khaled R., E-mail: Kh_rezk1966@yahoo.com [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Beherei, Hanan H. [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Physics Dept., Faculty of Science, El-Taif University (Saudi Arabia); El Bassyouni, Gehan T. [Biomaterials Dept., National Research Centre, El-Behoos St., Cairo (Egypt); Medical Physics Dept., Faculty of Medicine, El-Taif University (Saudi Arabia); El Mahallawy, Nahed [Design and Production Engineering Department, Faculty of Engineering, Ain Shams University on secondment to the German University in Cairo (Egypt)

    2013-10-15

    In the current study, the semiconducting metal oxides such as nano-ZnO and SiO{sub 2} powders were prepared via sol–gel technique and conducted on nano-hydroxyapatite (nHA) which was synthesized by chemical precipitation. The properties of fabricated nano-structured composites containing different ratios of HA, ZnO and SiO{sub 2} were examined using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The effect of the variation of ratios between the three components on mechanical, microstructure and in-vitro properties was assessed to explore the possibility of enhancing these properties. The results proved that the mechanical properties exhibited an increment with increasing the ZnO content at the extent of HA. In-vitro study proved the formation and nucleation of apatite onto the surface of the fabricated composites after one week of immersion. It is concluded that HA composites containing SiO{sub 2} or SiO{sub 2}/ZnO content had a suitable mechanical properties and ability to form apatite particles onto the composite surface. Based on bioactivity behavior, Si-HA is more bioactive than pure hydroxyapatite and nano-arrangements will provide an interface for better bone formation. Therefore, these nano-composites will be promising as bone substitutes especially in load bearing sites. - Graphical abstract: Nano-structures of (a) HA, (b) ZnO and (c) SiO{sub 2} powders. Highlights: • The nano-structured composites containing different ratios of HA, ZnO and SiO{sub 2} were prepared. • ZnO helps improve the mechanical properties of HA composites. • SiO{sub 2} helps improve the bioactivity of HA composites.

  11. Synthesis of Poly aniline-Montmorillonite Nano composites Using H2O2 as the Oxidant

    International Nuclear Information System (INIS)

    Binitha, N.; Binitha, N.; Suraja, V.; Zahira Yaakob; Sugunan, S.

    2011-01-01

    Poly aniline montmorillonite nano composite was prepared using H 2 O 2 as the oxidant. The catalytic environment of montmorillonite favours polymerization. Intercalation and composite formation was proven from various techniques such as XRD, FTIR, DRS and thermal analysis. XRD patterns give the dimension of the intercalated PANI, from the shift of 2θ values, which is in the nano range. FTIR showed that PANI composite formation occurred without affecting the basic clay layer structure. Thus the successful development of an alternative cheap route for poly aniline-montmorillonite nano composite was well established. (author)

  12. Chemical Functionalization, Self-Assembly, and Applications of Nano materials and Nano composites 2014

    International Nuclear Information System (INIS)

    Yan, X.; Jiao, T.; Balan, L.; Chen, X.; Hu, M.Z.; Liu, W.

    2014-01-01

    The growing interests in nano materials and nano composites call for the development of processing techniques to obtain multiple functionalization nano structures and achieve the tailoring of specific features of the nanometer size. Functional nano materials and nano composites will expand the applied range of the original material and at the same time promote the development of inter discipline. Thus, the chemical functionalization and bottom-up assemblies of nano materials and subsequent applications will accelerate the development of nano science and nano technology.

  13. Preliminary characterization in the development of the nano composite low density polyethylene with attapulgite clay

    International Nuclear Information System (INIS)

    Domingos, Luanda G.; Rego, Jose K.M.A. do; Ito, Edson N.; Acchar, Wilson

    2011-01-01

    The aim of this study was a preliminary study of the physical, thermal and rheological properties of the materials to be used in the development of nano composite low density polyethylene (LDPE) with Brazilian attapulgite clay (ATP), with and without the use of a compatibilizing agent interfacial, polyethylene grafted with maleic anhydride (PE-g-MAH). The materials were characterized by X-ray diffraction (XRD), thermogravimetry (TG) and torque rheometry. The materials were characterized and potentially could be developed polymeric nano composites with technological applications using attapulgite fibers in the nanometer scale. (author)

  14. Characterization of nano-composite PVD coatings for wear-resistant applications

    NARCIS (Netherlands)

    Galvan, D.; Pei, Y.T.; de Hosson, J.T.M.; DeHosson, JTM; Brebbia, CA; Nishida, SI

    2005-01-01

    Various methodologies for the characterization of nano-composite coatings are discussed, which consist TiC nano-particles distributed in an amorphous hydrocarbon (a-C:H) matrix. Complications that arise from the influence of coating roughness and underlying substrate on the properties are evaluated

  15. Preparation and characterization of poly(lactic acid)/ zinc-aluminium layered double hydroxide nano composites

    International Nuclear Information System (INIS)

    Eili Mahboobeh; Wan Mohd Zin Wan Yunus; Zobir Hossein; Mansor Ahmad; Norazowa Ibrahim

    2009-01-01

    Full text: Poly (lactic acid)/ stearate - zinc aluminum layered double hydroxide/ (PLA/ SZnAl LDH) nano composites were prepared via solution intercalation process using a modified ZnAl LDH. The anionic clay Zn 3 Al-NO 3 -LDH was prepared by a co-precipitation method and then modified with stearate ions by ion exchange process. Stearate-ZnAl LDH particles were then homogeneously dispersed in PLA matrix by a solution casting method. The pristine and modified ZnAl LDH was characterized by X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) spectroscopy which suggested that the modification was successful. The XRD analysis showed that during modification of LDH, the basal spacing increased from 8.83 Angstrom to 40.1 Angstrom. The PLA/ ZnAl LDH nano composites were characterized by tensile testing and XRD. The obtained nano composites showed dramatic enhancements in elongation at break as compared to those of the pure PLA. XRD results indicated that the materials formed are nano composites. (author)

  16. Energy Analysis of Contention Tree-Based Access Protocols in Dense Machine-to-Machine Area Networks

    Directory of Open Access Journals (Sweden)

    Francisco Vázquez-Gallego

    2015-01-01

    Full Text Available Machine-to-Machine (M2M area networks aim at connecting an M2M gateway with a large number of energy-constrained devices that must operate autonomously for years. Therefore, attaining high energy efficiency is essential in the deployment of M2M networks. In this paper, we consider a dense M2M area network composed of hundreds or thousands of devices that periodically transmit data upon request from a gateway or coordinator. We theoretically analyse the devices’ energy consumption using two Medium Access Control (MAC protocols which are based on a tree-splitting algorithm to resolve collisions among devices: the Contention Tree Algorithm (CTA and the Distributed Queuing (DQ access. We have carried out computer-based simulations to validate the accuracy of the theoretical models and to compare the energy performance using DQ, CTA, and Frame Slotted-ALOHA (FSA in M2M area networks with devices in compliance with the IEEE 802.15.4 physical layer. Results show that the performance of DQ is totally independent of the number of contending devices, and it can reduce the energy consumed per device in more than 35% with respect to CTA and in more than 80% with respect to FSA.

  17. Radiation Processing of Active Biodegradable Green Nano Composite Materials for Packaging Purposes

    International Nuclear Information System (INIS)

    AbdEl-Rehim, Hassan A.; Hegazy, El-Sayed A.; Raafat, Ahmed

    2011-01-01

    Clean and green reduction process of silver ions and graphene (GO) into nanosilver metal and graphene (GR) nanosheets respectively was achieved via gamma irradiation. The efficiency of gamma radiation to reduce silver ions and graphene oxide (GO) was investigated using UV-vis spectroscopy. Effects of gaseous atmosphere type, dispersion pH value, capping agent type and irradiation dose on GR nano-sheets formation were investigated. The presence of capping agent such as sodium carboxymethyl cellulose (CMC) or cellulose acetate is proven to be crucial. The obtained GR nanosheets and nanosilver metals are characterized using atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD) as well as thermo-gravimetric analyzer (TGA) and differential scanning calorimeter (DSC). Effectiveness, simplicity, reproducibility, and low energy consumption are the merits of using the Gamma radiation technique. Furthermore, the capping agent is eco-friendly and the dispersion is stable for months at room temperature. This approach can open up large-scale production of GR nanosheets and nanosilver metals. The prepared Nano-silver can be mixed with different natural polymer like CA to form Nano-composite films. The excellent physical properties of CA did not affect by addling Ag. The ionizing radiation has un-significant effect on the properties of CA-Ag nano composites films The CA-Ag nano composites posses biological activity towards different microorganisms. On other hand graphene or graphene oxide dispersions might be of interesting for producing biological active packaging films. Go as nanofillers has used for fabrication of a biocomposite with chitosan. The significantly improved in Chitosan /Go nano composites physical properties, including mechanical property, electrical conductivity, and structural stability, was demonstrated. Properties of the CA-Ag and Chitosan /Go nano composites suggest

  18. Radiation Processing of Active Biodegradable Green Nano Composite Materials for Packaging Purposes

    Energy Technology Data Exchange (ETDEWEB)

    AbdEl-Rehim, Hassan A.; Hegazy, El-Sayed A.; Raafat, Ahmed [National Center for Radiation Research and Technology NCRRT, Atomic Energy Authority, Cairo, Egypt P. O. Box 29, Nasr City, Cairo (Egypt)

    2011-07-01

    Clean and green reduction process of silver ions and graphene (GO) into nanosilver metal and graphene (GR) nanosheets respectively was achieved via gamma irradiation. The efficiency of gamma radiation to reduce silver ions and graphene oxide (GO) was investigated using UV-vis spectroscopy. Effects of gaseous atmosphere type, dispersion pH value, capping agent type and irradiation dose on GR nano-sheets formation were investigated. The presence of capping agent such as sodium carboxymethyl cellulose (CMC) or cellulose acetate is proven to be crucial. The obtained GR nanosheets and nanosilver metals are characterized using atomic force microscopy (AFM), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD) as well as thermo-gravimetric analyzer (TGA) and differential scanning calorimeter (DSC). Effectiveness, simplicity, reproducibility, and low energy consumption are the merits of using the Gamma radiation technique. Furthermore, the capping agent is eco-friendly and the dispersion is stable for months at room temperature. This approach can open up large-scale production of GR nanosheets and nanosilver metals. The prepared Nano-silver can be mixed with different natural polymer like CA to form Nano-composite films. The excellent physical properties of CA did not affect by addling Ag. The ionizing radiation has un-significant effect on the properties of CA-Ag nano composites films The CA-Ag nano composites posses biological activity towards different microorganisms. On other hand graphene or graphene oxide dispersions might be of interesting for producing biological active packaging films. Go as nanofillers has used for fabrication of a biocomposite with chitosan. The significantly improved in Chitosan /Go nano composites physical properties, including mechanical property, electrical conductivity, and structural stability, was demonstrated. Properties of the CA-Ag and Chitosan /Go nano composites suggest

  19. Nano-composite powders Ag-SnO2 prepared by reactive milling sintering and microstructural evolution

    International Nuclear Information System (INIS)

    Lorrain, Nathalie

    2000-01-01

    This work aims at controlling the synthesis and the sintering of nano-composite powders Ag-SnO 2 in order to obtain a dense and nano-structured material for electrical contact as a substitute of the toxic compound Ag - CdO. The powder is prepared by reactive milling from silver oxide (Ag 2 O) and silver bronze (Ag 3 Sn) powders. This process leads to a fine dispersion of silver and tin oxide nanometer sized particles. We first studied the mechanisms of reaction promoted by milling in vacuum and in air. A two-stage oxidation of tin in Ag 3 Sn occurs: during forced contact with Ag 2 O, tin oxidises in SnO, then in SnO 2 . In air, gaseous oxygen also participates to the oxidation of tin in SnO 2 but the reaction is slower because of the formation of silver carbonates from a reaction of Ag 2 O with CO 2 .Then the sintering behaviour of the nano-composite powder as a function of the compacting pressure and of the heating rate has been studied. We show: (i) a diffusion of pure silver towards porosity and free surfaces (exo-diffusion) which destroys the nano-structure and (ii) a severe de-densification. We show that the origin of these phenomena is due to carbonates on to the Ag 2 O starting powder, which are incorporated, in the milled Ag-SnO 2 powder in course of milling; during sintering, decomposition gases generate internal stresses. Low stresses lead to a diffusional creep with exo-diffusion whereas high stresses induce an intensive de-densification by local plastic deformation but no exo-diffusion. A modelling shows that exo-diffusion is limited by heating very quickly a strongly compacted powder that contains a high quantity of carbonates. The experimental results confirm the predictions of the model. Finally, we propose solutions allowing a full densification and a process for decreasing the tin oxide concentration. (author) [fr

  20. [Study on biocompatibility of hydroxyapatite/high density polyethylene (HA/HDPE) nano-composites artificial ossicle].

    Science.gov (United States)

    Wang, Guohui; Zhu, Shaihong; Tan, Guolin; Zhou, Kechao; Huang, Suping; Zhao, Yanzhong; Li, Zhiyou; Huang, Boyun

    2008-06-01

    This study was aimed to evaluate the biocompatibility of Hydroxyapatite/High density polyethylene (HA/ HDPE) nano-composites artificial ossicle. The percentage of S-period cells were detected by flow cytometry after L929 cells being incubated with extraction of the HA/HDPE nano-composites; the titanium materials for clinical application served as the contrast. In addition, both materials were implanted in animals and the histopathological evaluations were conducted. There were no statistically significant differences between the two groups (P >0.05). The results demonstrated that the HA/HDPE nano-composite artificial ossicle made by our laboratory is of a good biocompatibility and clinical application outlook.

  1. Influence of Compatibilizer and Processing Conditions on Morphology, Mechanical Properties, and Deformation Mechanism of PP/Clay Nano composite

    International Nuclear Information System (INIS)

    Akbari, B.; Bagheri, R.

    2012-01-01

    Polypropylene/montmorillonite nano composite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nano composite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD) and transmission optical microscopy (TOM) techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of nano composite.

  2. One-step solution combustion synthesis of Fe{sub 2}O{sub 3}/C nano-composites as anode materials for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Li, Peiyang; Deng, Jiachun; Li, Ying [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Liang, Wei, E-mail: liangwei@tyut.edu.cn [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Kun [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Kang, Litao, E-mail: kangltxy@gmail.com [Nano-Energy Inorganic Materials Laboratory, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zeng, Shaozhong; Yin, Shanhui; Zhao, Zhigang [Chery Automobile Co. Ltd., Wuhu 241006 (China); Liu, Xuguang; Yang, Yongzhen [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Gao, Feng [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)

    2014-03-25

    Highlights: • Fe{sub 2}O{sub 3}/C composite anode materials were prepared by a solution combustion process. • The carbon content could be adjusted by regulating the ratio of oxidizer/fuel. • The Fe{sub 2}O{sub 3}/C composite showed capacity 470 mA h g{sup −1} at the 80th cycle at 125 mA g{sup −1}. -- Abstract: This article describes a one-step solution combustion route (within 30 min at 350 °C in air) to prepare Fe{sub 2}O{sub 3} anode materials for lithium ion batteries (LIBs) from Fe(NO{sub 3}){sub 3}⋅9H{sub 2}O solution with citric acid. XRD, SEM-EDX and TEM showed that the product consisted a mixture of nano-sized α-Fe{sub 2}O{sub 3} and γ-Fe{sub 2}O{sub 3} crystals that agglomerated into porous particles. Significantly, in situ formed carbon could be introduced into the product (i.e., Fe{sub 2}O{sub 3}/C nano-composites) by simply increasing the dosage of citric acid in the precursor solution. The as-prepared Fe{sub 2}O{sub 3}/C nano-composite exhibited high reversible capacities of 470 and 419 mA h g{sup −1} at the 80th and 200th cycles with a current density of 125 mA g{sup −1}, which are much higher than those of counterparts without carbon (i.e., Fe{sub 2}O{sub 3} nano-particles). Comparison experiments correlated with the performance improvement of Fe{sub 2}O{sub 3}/C nano-composites with in situ formed carbon, well-developed mesopores and relatively high specific surface areas.

  3. Optical properties study of nano-composite filled D shape photonic crystal fibre

    Science.gov (United States)

    Udaiyakumar, R.; Mohamed Junaid, K. A.; Janani, T.; Maheswar, R.; Yupapin, P.; Amiri, I. S.

    2018-06-01

    With the nano-composite materials gaining momentum in the optical field, a new nano-composite filled D shape Photonic Crystal Fiber (PCF) is designed and the various optical properties are investigated with help of Finite Element Method. In the proposed structure the D-shape PCF is made up of silica with embedded silver nanoparticles and air holes are distributed along the fibre. The designed fibre shows various optical properties such as dispersion, birefringence, beat length and loss with respect to wavelength and compared with different filling factor like 0.1, 0.3 and 0.5. From our estimation and comparative analysis, it has been proved that the fibre loss has been decreased with increasing filling factor. Further this also showed flat dispersion at maximum filling factor.

  4. Conductive nano composites based on cellulose nano fiber coated poly aniline via in situ polymerization

    International Nuclear Information System (INIS)

    Silva, Michael J. da; Sanches, Alex O.; Malmonge, Luiz F.; Malmonge, Jose A.; Medeiros, Eliton S. de; Rosa, Morsyleide F.

    2011-01-01

    Cellulose nano fiber (CNF) was extracted by acid hydrolysis from cotton microfibril and nano composites of CNF/PANI-DBSA were obtained by in situ polymerization of aniline onto CNF. The ratios between DBSA/aniline and aniline/oxidant were varied and the nano composites were characterized by four probes direct current (dc) electrical conductivity, ultraviolet-visible (UV-Vis-NIR) and FTIR spectroscopy and X-ray diffraction (XRD). Electrical conductive about ∼10 -1 S/cm was research and was independent of DBSA/aniline molar ratio between 2-4 and the aniline/oxidant molar ratio between 1-5. X-ray patterns of the samples show crystalline peaks characteristic of cellulose I. The FTIR spectra confirmed the presence of PANI and CNF in all samples. (author)

  5. Preparation and performance of ZnO/Polyaniline nano-composite for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Yu, S.P.; Chang, X.C.; Wang, Z.M.; Han, K.F.; Zhu, H. [Beijing Univ. of Chemical Technology, Beijing (China). School of Science

    2010-07-01

    Supercapacitors combine the advantages of traditional capacitors and batteries. In this study, a zinc oxide (ZnO-PANI) nano-composite material was fabricated in order to investigate its behaviour in a supercapacitor application. The ZnO nano-powder was synthesized using the sol-gel method. An inverted emulsion polymerization method was then used to prepare the ZnO/PANI nanocomposite. X-ray diffraction (XRD) analyses demonstrated that the prepared ZnO had a hexagonal structure. The ZnO/PANI composite electrode was prepared. Electrochemical impedance spectroscopy (EIS) analyses indicated that the nano-composite material functioned well as an electrode. The highest capacitance rating achieved by the electrode was 31.82 F per g. 6 refs., 4 figs.

  6. Morphology of Poly lactide/Polycaprolactone (PLA/PCL) Nano composite by Scanning Electron Microscopy (SEM)

    International Nuclear Information System (INIS)

    Siti Zulaiha Hairaldin; Wan Md Zin Wan Yunus; Norazowa Ibrahim

    2011-01-01

    In this study, Octadecylamine Modified Montmorillonites (ODAMMT) were used to prepare Poly lactide/ Polycaprolactone (PLA/ PCL) nano composites. PLA and PCL mix in 90:10 ratios, using an internal mixer by melt blending technique. The other sample was blend with Natrium Montmorillonite (NaMMT) and Octadecylamine Modified Montmorillonite (ODA-MMT) to produce PLA/ PCL-NaMMT and PLA/ PCL ODAMMT. To characterize the polymer nano composites, X-ray diffraction (XRD), FTIR and SEM analysis were conducted. Comparison of morphology were made up between PLA/ PCL, PLA/ PCL with presence of 7 % of Na-MMT and 7 % ODA-MMT respectively based on SEM micrograph by calculate the number-average diameter. (author)

  7. Finite Element Model Characterization Of Nano-Composite Thermal And Environmental Barrier Coatings

    Science.gov (United States)

    Yamada, Yoshiki; Zhu, Dongming

    2011-01-01

    Thermal and environmental barrier coatings have been applied for protecting Si based ceramic matrix composite components from high temperature environment in advanced gas turbine engines. It has been found that the delamination and lifetime of T/EBC systems generally depend on the initiation and propagation of surface cracks induced by the axial mechanical load in addition to severe thermal loads. In order to prevent T/EBC systems from surface cracking and subsequent delamination due to mechanical and thermal stresses, T/EBC systems reinforced with nano-composite architectures have showed promise to improve mechanical properties and provide a potential crack shielding mechanism such as crack bridging. In this study, a finite element model (FEM) was established to understand the potential beneficial effects of nano-composites systems such as SiC nanotube-reinforced oxide T/EBC systems.

  8. Marginal and internal fit of nano-composite CAD/CAM restorations

    Directory of Open Access Journals (Sweden)

    So-Hyun Park

    2016-02-01

    Full Text Available Objectives The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. Materials and Methods A full veneer crown and an mesio-occluso-distal (MOD inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU and experimental nano-composite CAD/CAM blocks (EB under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Results Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000. In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001. Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000. Conclusions The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.

  9. Removal of light petroleum hydrocarbons from water sources using polypropylene and titanium dioxide nano-composite

    Directory of Open Access Journals (Sweden)

    H. Karyab

    2016-08-01

    Full Text Available Background: Petroleum hydrocarbons are the most important pollutants which threat human health and aquatics. Adsorbents are one of the common equipment in water pollution management; however, their applications have been associated with limitations. Objective: To evaluate the potential of polypropylene/titanium dioxide Nano-composite in adsorption of light petroleum hydrocarbons from water sources. Methods: This experimental study was conducted at school of health, Qazvin University of Medical Sciences in 2014-15. Activation of polypropylene fibers, with 1 cm length and 300 microns diameters, was achieved with wet heating. To synthesize of nano-composite the fibers were coated with nano-titanium dioxide with 20 nm diameter. The sonication was performed at 26 kHz and 100 W of power in 40ºc. The morphology of the fractured surfaces of impact specimens was examined by FESEM. The adsorption rate of petrol and gasoline, as surrogate of TPH, was evaluated in different retention time within polyamide mesh aperture diameter of 250 nm. Average of TPH adsorbing, per unit weight of adsorbent, were analyzed with analysis of variance and Scheffe post hoc tests. Findings: The FESEM micrographs showed that the dispersion of the nano-Tio2 particles was relatively good and only few aggregations exist. The maximum adsorption capacity of petrol and gasoline was obtained in 30 minute. The adsorption rate of gasoline was 6.49±0.10 g/g and oil was 7.01±0.13 g/g. Conclusion: According to the results and in comparison with commercial imported adsorbents, the synthesized Nano-composite had favorable performance. The results show that the polypropylene/Tio2 Nano-composite can be used effectively in light petroleum hydrocarbons removal from polluted water sources.

  10. BACTERICIDE IMPACT OF POLYMER-STABILIZED MULTI-FUNCTIONAL NANO-COMPOSITES

    OpenAIRE

    Graskova I.A.; М.А. Zhivet’yev; G.B. Borovskii; B.G. Sukhov

    2012-01-01

    Synthesis on the basis of natural matrices in order to acquire products with the desired properties is one of the promising trends of modern science. Using polysaccharides as a matrix allowed to generate derivatives with diverse structures and new properties. Growing interest towards anti-microbe effect of selenium-containing nano-composites is induced by the phenomenon of antibiotic-resistance of contemporary pathogenic microorganisms.Clavibacter genus bacteria are the most significant and w...

  11. Performance evaluation on solar still integrated with nano-composite phase change materials

    International Nuclear Information System (INIS)

    Rajasekhar, G.; Eswaramoorthy, M.

    2015-01-01

    This paper communicates the performance evaluation of single slope solar still integrated with nano-composite phase change materials and compare with the experimental results of with and without phase change materials. A solar still with 1 m"2 surface area is developed with non-selective coating of absorber sheet with the provision of thermal energy storage materials. The solar still is tested on typical days with and without thermal energy storage materials. It is found that from the experimental studies that nano-materials (Al_2O_3) dispersed in paraffin wax is giving better cumulative yield of distillate than paraffin wax alone and without paraffin wax thermal storage. The daily efficiency of the solar still is computed for solar still with nano-composite phase change materials is 45% and solar still paraffin wax alone thermal storage is 40% and solar still without any thermal storage is 38%. It is concluded from the experimental studies; solar still integrated with nano-composite phase change materials gives better performance than with and without phase change material alone. (authors)

  12. Oxidation Behavior of AlN/h-BN Nano Composites at High Temperature

    International Nuclear Information System (INIS)

    Jin Haiyun; Huang Yinmao; Feng Dawei; He Bo; Yang Jianfeng

    2011-01-01

    Both AlN/ nano h-BN composites and AlN/ micro h-BN composites were fabricated. The high temperature oxidation behaviors were investigated at 1000deg. C and 1300deg. C using a cycle-oxidation method. The results showed that there were little changes of both nano composites and monolithic AlN ceramic at temperature of 1000deg. C. And at 1300deg. C, the oxidation dynamics curve of composites could be divided into two courses: a slowly weight increase and a rapid weight decrease, but the oxidation behavior of nano composites was better than micro composites. It was due to that the uniform distribution of oxidation production (Al 18 B 4 O 33 ) surround the AlN grains in nano composites and the oxidation proceeding was retarded. The XRD analysis and SEM observations showed that there was no BN remained in the composites surface after 1300deg. C oxidation and the micropores remain due to the vaporizing of B 2 O 3 oxidized by BN.

  13. Progress in Tribological Properties of Nano-Composite Hard Coatings under Water Lubrication

    Directory of Open Access Journals (Sweden)

    Qianzhi Wang

    2017-02-01

    Full Text Available The tribological properties, under water-lubricated conditions, of three major nano-composite coatings, i.e., diamond-like carbon (DLC or a-C, amorphous carbon nitride (a-CNx and transition metallic nitride-based (TiN-based, CrN-based, coatings are reviewed. The influences of microstructure (composition and architecture and test conditions (counterparts and friction parameters on their friction and wear behavior under water lubrication are systematically elucidated. In general, DLC and a-CNx coatings exhibit superior tribological performance under water lubrication due to the formation of the hydrophilic group and the lubricating layer with low shear strength, respectively. In contrast, TiN-based and CrN-based coatings present relatively poor tribological performance in pure water, but are expected to present promising applications in sea water because of their good corrosion resistance. No matter what kind of coatings, an appropriate selection of counterpart materials would make their water-lubricated tribological properties more prominent. Currently, Si-based materials are deemed as beneficial counterparts under water lubrication due to the formation of silica gel originating from the hydration of Si. In the meantime, the tribological properties of nano-composite coatings in water could be enhanced at appropriate normal load and sliding velocity due to mixed or hydrodynamic lubrication. At the end of this article, the main research that is now being developed concerning the development of nano-composite coatings under water lubrication is described synthetically.

  14. Characterization of dispersion of a nano composites PP/TiO2 non modified

    International Nuclear Information System (INIS)

    Soares, Igor L.; Tavares, Maria I.B.; Silva, Vanessa A. da; Legramanti, Cintia; Luetkmeyer, Leandro

    2011-01-01

    Polymeric nano composites are composite materials where an inorganic particle, which has a dimension in the nanometer range, is dispersed in a polymer matrix. Nano composites, using polypropylene (PP) as matrix polymer and titanium dioxide (TiO 2 ) as filler, have great versatility in marketing applications, this factor is inherent in the PP and the inherent ability photo degraded TiO 2 particles. This combination can lead to a widely used material and a degradation time after discharge reduced, there by becoming, a residue of low environmental impact. This study aimed to evaluate the dispersion and particle distribution of TiO 2 , non modified, in PP matrix, using the process of preparation by melt extrusion pathway and characterization of the materials obtained: on the molecular dynamics, using low field NMR solid state, measures the relaxation time spin-network (T 1 H); morphology using XRD technique, and thermal analysis technique with the TGA of pure PP and nano composites PP/TiO 2 . (author)

  15. Are nano-composites and nano-ionomers suitable for orthodontic bracket bonding?

    Science.gov (United States)

    Uysal, Tancan; Yagci, Ahmet; Uysal, Banu; Akdogan, Gülsen

    2010-02-01

    The aim of this study was to test nano-composite (Filtek Supreme Plus Universal) and a newly introduced nano-ionomer (Ketac N100 Light Curing Nano-Ionomer) restorative to determine their shear bond strength (SBS) and failure site locations in comparison with a conventional light-cure orthodontic bonding adhesive (Transbond XT). Sixty freshly extracted human maxillary premolar teeth were arbitrarily divided into three equal groups. The brackets were bonded to the teeth in each group with different composites, according to the manufacturers' instructions. The SBS values of the brackets were recorded in Megapascals (MPa) using a universal testing machine. Adhesive remnant index scores were determined after failure of the brackets. The data were analysed using analysis of variance, Tukey honestly significant difference, and chi-square tests. The results demonstrated that group 1 (Transbond XT, mean: 12.60 +/- 4.48 MPa) had a higher SBS than that of group 2 (nano-composite, mean: 8.33 +/- 5.16 MPa; P nano-ionomer, mean: 6.14 +/- 2.12 MPa; P Nano-composites and nano-ionomers may be suitable for bonding since they fulfil the previously suggested SBS ranges for clinical acceptability, but they are inferior to a conventional orthodontic composite.

  16. Novel Nano-Composite Catalysts for Renewable Energy Storage Applications

    Science.gov (United States)

    Devaguptapu, Surya Vamsi

    Spinel NiCo2O4 catalysts are considered the promising precious metal-free catalyst for oxygen reactions. Significant efforts are mainly explore optimal chemical doping and substituent to tune its electronic structures for enhanced performance. Here, we focuses on morphology control and determine the morphology-dependent activity for bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In particular, three types of spinel NiCo2O4 were prepared using temple-free, SiO 2 hard template, and Pluronic-123 soft template hydrothermal methods, showing significantly different morphologies, respectively. In particular, template-free method yield dense structures. Sold-template method assists the formation of porous and hollow structures. Importantly, the soft template is effective to prepare a unique nanoflower morphology containing abundant rose petal (needle) like structures. The effect of the utilization of templates, both soft and hard as well as a template free synthesis on the morphology as well as the activity and stability of the final catalyst is investigated. Compared to others, the nanoflower-like NiCo2O4 exhibited the highest bifunctional catalytic activity simultaneously for ORR and OER, likely due to the facile absorption of oxygen molecules on increased surface areas with efficient mass transfer. The nanoflower NiCo2O 4 also exhibited an onset and half-wave potentials of 0.94 and 0.82 V for the ORR in alkaline media. Although it is still inferior to state of the art Pt, the new type of spinel NiCo2O4 catalyst represents the best activity compared to reported carbon-free oxides. Meanwhile, OER activity and stability were achieved with an onset potential of 1.48 V generating a current density of 14 mA/cm2 at 1.6 V. The OER activity does not declined after 10,000 potential cycles demonstrating excellent stability, which is superior to the benchmark of Ir for the OER. This work provides an effective solution to enhance catalytic activity

  17. A review on mechanical properties of magnesium based nano composites

    Science.gov (United States)

    Tarafder, Nilanjan; Prasad, M. Lakshmi Vara

    2018-04-01

    A review was done on Magnesium (Mg) based composite materials reinforced with different nano particles such as TiO2, Cu, Y2O3, SiC, ZrO2 and Al2O3. TiO2 and Al2O3 nanoparticles were synthesised by melt deposition process. Cu, Y2O3, SiC and ZrO2 nanoparticles were synthesised by powder metallurgy process. Composite microstructural characteristics shows that the nano-size reinforcements are uniformly distributed in the composite matrix and also minimum porosity with solid interfacial integrity. The mechanical properties showed yield strength improvement by 0.2 percentage and Ultimate tensile strength (UTS) was also improved for all the nano-particles. But UTS was adversely affected with TiO2 reinforcement while ductility was increased. With Cu reinforcement elastic modulus, hardness and fracture resistance increased and improved the co-efficient of thermal expansion (CTE) of Mg based matrix. By Y2O3 reinforcement hardness, fracture resistance was improved and ductility reached maximum by 0.22 volume percentage of Y2O3 and decreased with succeeding increase in Y2O3 reinforcement. The readings exposed that mechanical properties were gathered from the composite comprising 2.0 weight percentage of Y2O3. Ductility and fracture resistance increased with ZrO2 reinforcement in Mg matrix. Using Al2O3 as reinforcement in Mg composite matrix hardness, elastic modulus and ductility was increased but porosity reduced with well interfacial integrity. Dissipation of energy in the form of damping capacity was resolved by classical vibration theory. The result showed that an increasing up to 0.4 volume percentage alumina content increases the damping capacity up to 34 percent. In another sample, addition of 2 weight percentage nano-Al2O3 particles showed big possibility in reducing CTE from 27.9-25.9×10-6 K-1 in Magnesium, tensile and yield strength amplified by 40MPa. In another test, Mg/1.1Al2O3 nanocomposite was manufactured by solidification process followed by hot extrusion

  18. Polymer-layered silicate nano composite by UV-radiation curing: an original synthesis

    International Nuclear Information System (INIS)

    Keller, L.; Decker, C.; Zahouily, K.; Miehe-Brendle, J.; Le Meins, J.M.

    2004-01-01

    Full text.Because of the many hopes which they raise, the nano composite materials are the subject of an increasing number of scientific publications. Indeed, the intimate association of a polymer matrix and silicate nano-platelets leads to the formation of materials having mechanical and barriers properties improved (fire, gas, humidity...). A literature survey shows that these materials are generally produced by a thermal polymerization, which presents two major disadvantages: the use of organic solvents and a great consumption of energy. To overcome such limitations, photo initiated polymerization was chosen to synthesize nano composite materials. By this technology, called UV radiation curing, a solvent-free resin is transformed within seconds into a solid polymer upon exposure to UV-radiation at ambient temperature. The principal objective of this study was to develop photopolymerizable systems with clay particles having a layer structure (phyllosilicates). The clay mineral was made organophilic by treatment with an alkylammonium salt to allow the acrylate resin to penetrate into the expanded galleries. A morphological characterization of the materials obtained was carried out by X-rays diffraction and electronic microscopy transmission. The polymerization of the various resins under the UV exposure was followed in situ by using the real-time infrared spectroscopy (RT-FTIR) and attenuated total reflection (ATR). The results obtained show that the presence of the organo clay does not modify much the polymerization kinetics. The nano composite material thus obtained is transparent, insoluble in the organic solvents and presents improved mechanical properties, compared to the neat resin and the micro composite, for a load factor ranging between 2 and 5%wt. The addition of nanoparticles also makes it possible to reduce efficiently the brightness of coatings UV and finally confers to this material barriers properties higher than that of the photo crosslinked

  19. Exergy analysis of the solar still integrated nano composite phase change materials

    International Nuclear Information System (INIS)

    Methre, V.K.; Eswaramoorthy, M.

    2015-01-01

    This paper communicates the exergy analysis of solar still integrated with nano composite phase change materials for design and operating parameters. Al_2O_3 nano materials (50 nm) is dispersed by weight ratio in paraffin wax at melting state and its thermophysical properties are evaluated using developed correlation. Exergy balance equation for basin liner, thermal energy storage, glass cover and saline water is developed and exergy efficiency is analysed. It is found that exergy efficiency is improved by higher weight ratio of Al_2O_3 nano materials with paraffin wax alone. (author)

  20. Digital laser printing of metal/metal-oxide nano-composites with tunable electrical properties

    International Nuclear Information System (INIS)

    Zenou, M; Kotler, Z; Sa’ar, A

    2016-01-01

    We study the electrical properties of aluminum structures printed by the laser forward transfer of molten, femtoliter droplets in air. The resulting printed material is an aluminum/aluminum-oxide nano-composite. By controlling the printing conditions, and thereby the droplet volume, its jetting velocity and duration, it is possible to tune the electrical resistivity to a large extent. The material resistivity depends on the degree of oxidation which takes place during jetting and on the formation of electrical contact points as molten droplets impact the substrate. Evidence for these processes is provided by FIB cross sections of printed structures. (paper)

  1. Study of rheological, viscoelastic and vulcanization behavior of sponge EPDM/NR blended nano- composites

    International Nuclear Information System (INIS)

    Bashir, M Arshad; Shahid, M; Ahmed, Riaz; Yahya, A G

    2014-01-01

    In this research paper the effect of blending ratio of natural rubber (NR) with Ethylene Propylene Diene Monomer (EPDM) were investigated. Different samples of EPDM/NR ratio were prepared to study the variation of NR in EPDM on rheology, curing characteristics, tangent δ, and viscosity variation during vulcanization of sponge nano composites.The main aim of present research is to develop elastomeric based sponge composites with the blending ratio of base elastomers along with the carbon nano particles for high energy absorbing and damping applications. The curing characteristics, rheology and viscoelastic nature of the composite is remarkably influenced with the progressive blending ratio of the base elastomeric matrix

  2. Study of rheological, viscoelastic and vulcanization behavior of sponge EPDM/NR blended nano-composites

    International Nuclear Information System (INIS)

    Bashir, M. A.; Shahid, M.; Ahmed, R.; Yahya, A. G.

    2013-01-01

    In this research paper the effect of blending ratio of natural rubber (NR) with Ethylene Propylene Diene Monomer (EPDM) were investigated. Different samples of EPDM/NR ratio were prepared to study the variation of NR in EPDM on rheology, curing characteristics, tangent d, and viscosity variation during vulcanization of sponge nano composites. The main aim of present research is to develop elastomeric based sponge composites with the blending ratio of base elastomers along with the carbon nano particles for high energy absorbing and damping applications. The curing characteristics, rheology and viscoelastic nature of the composite is remarkably influenced with the progressive blending ratio of the base elastomeric matrix. (author)

  3. Electrochemical Synthesis of Graphene/MnO2 Nano-Composite for Application to Supercapacitor Electrode.

    Science.gov (United States)

    Jeong, Kwang Ho; Lee, Hyeon Jeong; Simpson, Michael F; Jeong, Mun

    2016-05-01

    Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrate enhanced contact between the electrode and electrolyte and improved power density as an electrochemical capacitor.

  4. Fracture toughness of epoxy/multi-walled carbon nanotube nano-composites under bending and shear loading conditions

    International Nuclear Information System (INIS)

    Ayatollahi, M.R.; Shadlou, S.; Shokrieh, M.M.

    2011-01-01

    Research highlights: → Mode I and mode II fracture tests were conducted on epoxy/MWCNT nano-composites. → Addition of MWCNT to epoxy increased both K Ic and K IIc of nano-composites. → The improvement in K IIc was more pronounced than in K Ic . → Mode I and mode II fracture surfaces were studied by scanning electron microscopy. -- Abstract: The effects of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of epoxy/MWCNT nano-composites were studied with emphasis on fracture toughness under bending and shear loading conditions. Several finite element (FE) analyses were performed to determine appropriate shear loading boundary conditions for a single-edge notch bend specimen (SENB) and an equation was derived for calculating the shear loading fracture toughness from the fracture load. It was seen that the increase in fracture toughness of nano-composite depends on the type of loading. That is to say, the presence of MWCNTs had a greater effect on fracture toughness of nano-composites under shear loading compared with normal loading. To study the fracture mechanisms, several scanning electron microscopy (SEM) pictures were taken from the fracture surfaces. A correlation was found between the characteristics of fracture surface and the mechanical behaviors observed in the fracture tests.

  5. Y2O3-MgO Nano-Composite Synthesized by Plasma Spraying and Thermal Decomposition of Solution Precursors

    Science.gov (United States)

    Muoto, Chigozie Kenechukwu

    This research aims to identify the key feedstock characteristics and processing conditions to produce Y2O3-MgO composite coatings with high density and hardness using solution precursor plasma spray (SPPS) and suspension plasma spray (SPS) processes, and also, to explore the phenomena involved in the production of homogenized nano-composite powders of this material system by thermal decomposition of solution precursor mixtures. The material system would find potential application in the fabrication of components for optical applications such as transparent windows. It was shown that a lack of major endothermic events during precursor decomposition and the resultant formation of highly dense particles upon pyrolysis are critical precursor characteristics for the deposition of dense and hard Y2O3-MgO coatings by SPPS. Using these principles, a new Y2O3-MgO precursor solution was developed, which yielded a coating with Vickers hardness of 560 Hv. This was a considerable improvement over the hardness of the coatings obtained using conventional solution precursors, which was as low as 110 Hv. In the thermal decomposition synthesis process, binary solution precursor mixtures of: yttrium nitrate (Y[n]) or yttrium acetate (Y[a]), with magnesium nitrate (Mg[n]) or magnesium acetate (Mg[a]) were used in order to study the effects of precursor chemistry on the structural characteristics of the resultant Y2O3-MgO powders. The phase domains were coarse and distributed rather inhomogeneously in the materials obtained from the Y[n]Mg[n] and Y[a]Mg[a] mixtures; finer and more homogeneously-distributed phase domains were obtained for ceramics produced from the Y[a]Mg[n] and Y[n]Mg[a] mixtures. It was established that these phenomena were related to the thermal characteristics for the decomposition of the precursors and their effect on phase separation during oxide crystallization. Addition of ammonium acetate to the Y[n[Mg[n] mixture changed the endothermic process to exothermic

  6. Impact of Surface Modification and Nanoparticle on Sisal Fiber Reinforced Polypropylene Nano composites

    International Nuclear Information System (INIS)

    Ibrahim, I. D.; Jamiru, T.; Sadiku, E. R.; Agwuncha, S. Ch.; Kupolati, W. K.

    2016-01-01

    The use of plant fibers, polymer, and nanoparticles for composite has gained global attention, especially in the packaging, automobile, aviation, building, and construction industries. Nano composites materials are currently in use as a replacement for traditional materials due to their superior properties, such as high strength-to-weight ratio, cost effectiveness, and environmental friendliness. Sisal fiber (SF) was treated with 5% NaOH for 2 hours at 70"°C. A mixed blend of sisal fiber and recycled polypropylene (rPP) was produced at four different fiber loadings: 10, 20, 30, and 40 wt.%, while nano clay was added at 1, 3, and 5 wt.%. Maleic anhydride grafted polypropylene (MAPP) was used as the compatibilizer for all composites prepared except the untreated sisal fibers. The characterization results showed that the fiber treatment, addition of MAPP, and nano clay improved the mechanical properties and thermal stability and reduced water absorption of the SF/rPP nano composites. The tensile strength, tensile modulus, and impact strength increased by 32.80, 37.62, and 5.48%, respectively, when compared to the untreated SF/rPP composites. Water absorption was reduced due to the treatment of fiber and the incorporation of MAPP and nano clay.

  7. Radiation induced synthesis of conducting polymers and their metal nano-composites

    International Nuclear Information System (INIS)

    Cui, Zhenpeng

    2017-01-01

    The aim of the present work is to demonstrate the versatility of the gamma (γ)-rays based radiolytic method and to extend our methodology to the synthesis of various conducting polymers (CPs) in water in different experimental conditions. Poly(3,4-ethylenedioxy-thiophene) (PEDOT) and poly-pyrrole (PPy) conjugated polymers were successfully prepared and characterized in solution and after deposition by complementary spectroscopic and microscopic techniques. Also their thermal stability and their electrical conductivity were studied and compared with those of CPs prepared by conventional methods. The influence of the nature of radiation-induced oxidizing radicals, of the ionic strength, of the medium, of the pH, of the presence of surfactant-based soft templates on the growth mechanism, on the efficiency of polymerization, on the morphology of the obtained CPs as well as on their absorption and conducting properties was checked. Also, the radiolytic method was extend to the synthesis of CPs/noble metal nano-composites. Different preparation methodologies were developed based on two-step method and one-pot method, by using oxidation route or reduction route. Our new radiolytic strategy described and extended in this manuscript opens the way for the preparation of different kinds of CPs and CPs nano-composites not only in aqueous solutions but also in various environments foreshadowing many promising applications.. (author)

  8. Micro/nano composited tungsten material and its high thermal loading behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jinglian, E-mail: fjl@csu.edu.cn; Han, Yong; Li, Pengfei; Sun, Zhiyu; Zhou, Qiang

    2014-12-15

    Tungsten (W) is considered as promising candidate material for plasma facing components (PFCs) in future fusion reactors attributing to its many excellent properties. Current commercial pure tungsten material in accordance with the ITER specification can well fulfil the performance requirements, however, it has defects such as coarse grains, high ductile–brittle transition temperature (DBTT) and relatively low recrystallization temperature compared with its using temperature, which cannot meet the harsh wall loading requirement of future fusion reactor. Grain refinement has been reported to be effective in improving the thermophysical and mechanical properties of W. In this work, rare earth oxide (Y{sub 2}O{sub 3}/La{sub 2}O{sub 3}) and carbides (TiC/ZrC) were used as dispersion phases to refine W grains, and micro/nano composite technology with a process of “sol gel – heterogeneous precipitation – spray drying – hydrogen reduction – ordinary consolidation sintering” was invented to introduce these second-phase particles uniformly dispersed into W grains and grain-boundaries. Via this technology, fine-grain W materials with near-full density and relatively high mechanical properties compared with traditional pure W material were manufactured. Preliminary transient high-heat flux tests were performed to evaluate the thermal response under plasma disruption conditions, and the results show that the W materials prepared by micro/nano composite technology can endure high-heat flux of 200 MW/m{sup 2} (5 ms)

  9. Fabrication of Surface Level Cu/Si Cp Nano composites by Friction Stir Processing Route

    International Nuclear Information System (INIS)

    Srinivasan, R. C.; Karunanithi, M.

    2015-01-01

    Friction stir processing (FSP) technique has been successfully employed as low energy consumption route to prepare copper based surface level nano composites reinforced with nano sized silicon carbide particles (Si Cp). The effect of FSP parameters such as tool rotational speed, processing speed, and tool tilt angle on microstructure and microhardness was investigated. Single pass FSP was performed based on Box-Behnken design at three factors in three levels. A cluster of blind holes 2 mm in diameter and 3 mm in depth was used as particulate deposition technique in order to reduce the agglomeration problem during composite fabrication. K-type thermocouples were used to measure temperature histories during FSP. The results suggest that the heat generation during FSP plays a significant role in deciding the microstructure and microhardness of the surface composites. Microstructural observations revealed a uniform dispersion of nano sized Si Cp without any agglomeration problem and well bonded with copper matrix at different process parameter combinations. X-ray diffraction study shows that no intermetallic compound was produced after processing. The microhardness of nano composites was remarkably enhanced and about 95% more than that of copper matrix

  10. Lithium-doped hydroxyapatite nano-composites: Synthesis, characterization, gamma attenuation coefficient and dielectric properties

    Science.gov (United States)

    Badran, H.; Yahia, I. S.; Hamdy, Mohamed S.; Awwad, N. S.

    2017-01-01

    Lithium-hydroxyapatite (0, 1, 5, 10, 20, 30 and 40 wt% Li-HAp) nano-composites were synthesized by sol-gel technique followed by microwave-hydrothermal treatment. The composites were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and Raman techniques. Gamma attenuation coefficient and the dielectric properties for all composites were investigated. The crystallinity degree of Li-doped HAp was higher than that of un-doped HAp. Gamma attenuation coefficient values increased from 0.562 cm-1 for 0 wt% Li-HAp to 2.190 cm-1 for 40 wt% Li-HAp. The alternating current conductivity increased with increasing frequency. The concentration of Li affect the values of dielectric constant where Li doped HAp of low dielectric constant can have an advantage for healing in bone fractures. The calcium to phosphorus ratio decreased from 1.43 to 1.37 with the addition of lithium indicating the Ca deficiency in the studied composites. Our findings lead to the conclusion that Li-HAp is a new nano-composite useful for medical applications and could be doped with gamma shield materials.

  11. Surface enhanced 316L/SiC nano-composite coatings via laser cladding and following cold-swaging process

    Science.gov (United States)

    Li, Yuhang; Gao, Shiyou

    2017-10-01

    Cold-swaging is one of a cold deformation processes, and ceramic-reinforcement nano-composite coatings can effectively improve the performance of metal matrix surface. Therefore, the two processes are innovatively combined to further improve the surface properties of the metal matrix in this paper. The microstructure and surface properties of the laser cladding 316L + 10 wt% SiC nano-composite coatings were examined through designed experiments after cold-swaging by self-developed hydraulic machine. Furthermore, the coatings were compared with those without cold-swaging coatings at the same time. The result shows that the cold-swaging process can further enhance the tensile strength, micro-hardness and the wear resistance of the composite coating. This study can be used as a reference for further strengthening of laser cladding nano-composite coatings in future research.

  12. Study on the nano-composite electroless coating of Ni-P/Ag

    International Nuclear Information System (INIS)

    Ma Hongfang; Tian Fang; Li Dan; Guo Qiang

    2009-01-01

    The nano-composite coating of Ni-P/Ag was obtained by adding silver nanoparticles to the Ni-P electroless plating solutions. The properties of the coating were tested by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), differential scanning calorimeter (DSC), X-ray diffraction (XRD) and microsclerometer. Silver nanoparticles changed the properties of the composite coating. The Ni-P electroless coating contains 12.23 wt.% P while the composite coating of Ni-P/Ag contains 11.17 wt.% P and 0.24 wt.% Ag. The hardness of the composite coating is bigger than that of Ni-P alloy coating. Differential scanning calorimeter studies showed the amorphous to crystalline transition with precipitation of Ni 3 P and Ni around 335 deg. C

  13. Mathematical Simulation of Temperature Profiles within Microwave Heated Wood Made for Wood-Based Nano composites

    International Nuclear Information System (INIS)

    Li, X.; He, X.; Lv, J.; Wu, Y.; Luo, Y.; Chen, H.

    2013-01-01

    High intensive microwave pretreatment is a new method to modify wood for the fabrication of wood-based nano composites. Based on the physical law on heat transfer, a mathematical model to describe the temperature profiles within wood heated by high intensive microwave was established and simulated in this research. The results showed that the temperature profiles within wood were related to microwave heating methods; The temperature inside wood firstly increased and then gradually decreased along the direction of microwave transmission when the unilateral microwave heating was applied, and the temperature difference along the thickness direction of wood was very significant; The temperature with wood firstly increased and then gradually decreased from the wood surface to interior when the bilateral microwave heating was applied. Compared with the unilateral microwave heating, bilateral microwave heating is a better microwave heating method for the more uniform wood microwave pretreatment.

  14. Effect of processing conditions on the mechanical properties of polypropylene/bentonite nano composites

    International Nuclear Information System (INIS)

    Alves, Tatianny S.; Cipriano, Pamela B.; Lira, Vanize F.; Canedo, Eduardo L.; Carvalho, Laura H. de

    2009-01-01

    This work dealt with the effect of processing conditions on the properties of polypropylene/bentonite compounds, using natural clay and an organoclay prepared with hexadecyl trimethyl ammonium bromide. Compounds with 1% clay were prepared by melt compounding in a single-screw extruder and in a counter-rotating twin-screw extruder, and characterized x-ray diffraction; tensile and impact mechanical tests. X ray diffraction results on clays and compounds show that the surfactant was incorporated within the clay galleries and that intercalated nano composites were obtained with the organoclay processed in either the single or the twin-screw extruder. The data also indicated that, without the addition of a compatibilizer, no significant variation of mechanical properties was observed for the composites processed in either extruder. (author)

  15. Glass transition temperature of polymer nano-composites with polymer and filler interactions

    Science.gov (United States)

    Hagita, Katsumi; Takano, Hiroshi; Doi, Masao; Morita, Hiroshi

    2012-02-01

    We systematically studied versatile coarse-grained model (bead spring model) to describe filled polymer nano-composites for coarse-grained (Kremer-Grest model) molecular dynamics simulations. This model consists of long polymers, crosslink, and fillers. We used the hollow structure as the filler to describe rigid spherical fillers with small computing costs. Our filler model consists of surface particles of icosahedra fullerene structure C320 and a repulsive force from the center of the filler is applied to the surface particles in order to make a sphere and rigid. The filler's diameter is 12 times of beads of the polymers. As the first test of our model, we study temperature dependence of volumes of periodic boundary conditions under constant pressures through NPT constant Andersen algorithm. It is found that Glass transition temperature (Tg) decrease with increasing filler's volume fraction for the case of repulsive interaction between polymer and fillers and Tg weakly increase for attractive interaction.

  16. Antimicrobial Activity of Hippurate Nano composite and Its Cytotoxicity Effect in Combination with Cytarabine against HL-60

    International Nuclear Information System (INIS)

    Al Ali, S.H.H.; Al-Qubaisi, M.; Ismail, M.; El Zowalaty, M.; Hussein, M.Z.; Ismail, M.

    2013-01-01

    Hippuric acid (HA) was intercalated into a zinc-layered hydroxide (ZLH) by direct reaction of an aqueous suspension of zinc oxide with an aqueous solution of hippuric acid to obtain hippurate nano composite (HAN). Various concentrations of hippuric acid (0.05, 0.2, and 0.4 molar) were used for the synthesis of the nano composite. The as-synthesized HAN using 0.2 molar was found to give a well-ordered layered nano composite material with an increase in the basal spacing to 21.3 Å which indicated the insertion of hippurate organic moiety into the ZLH interlayers. The cytotoxicity of HAN in combination with cytarabine against human promyelocytic leukemia cells (HL-60) was tested using MTT cell viability assay and trypan blue dye exclusion assay. The combination of cytarabine with HAN showed higher tumor suppression efficiency as compared to that of cytarabine alone. The IC 50 values of HAN/cytarabine combination and cytarabine alone were μg/mL and μg/mL, respectively. DNA fragmentation was also studied, and the exposure of HL-60 cells to cytarabine produced % DNA fragmentation compared to % when cells were exposed to combination of cytarabine with HAN. The antimicrobial activity of hippuric acid and HAN nano composite was carried out against Gram-positive bacteria, Gram-negative bacteria, and yeasts. It was found that Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus were more sensitive to HAN compared to Bacillus subtilis and Salmonella choleraesuis

  17. Effect of lateral size of graphene nano-sheets on the mechanical properties and machinability of alumina nano-composites

    Czech Academy of Sciences Publication Activity Database

    Porwal, H.; Saggar, Richa; Tatarko, P.; Grasso, S.; Saunders, T.; Dlouhý, Ivo; Reece, M. J.

    2016-01-01

    Roč. 42, č. 6 (2016), s. 7533-7542 ISSN 0272-8842 EU Projects: European Commission(XE) 264526 Institutional support: RVO:68081723 Keywords : Alumina * Graphene nano-sheets * Nano-composites * Mechanical properties * Machinability Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 2.986, year: 2016

  18. Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

    Science.gov (United States)

    Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

    2017-01-01

    In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

  19. The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

    Science.gov (United States)

    Yepez, Johanna

    Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

  20. Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite

    International Nuclear Information System (INIS)

    Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K.; Warrier, K.G.K.; Padmanabhan, P.V.A.

    2012-01-01

    Graphical abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ► A novel lanthanum phosphate–Y 2 O 3 nano composite is synthesized for the first time using a modified facile sol gel process. ► The composite becomes crystalline at 600 °C and X-ray diffraction pattern is indexed for monoclinic LaPO 4 and cubic yttria. ► The composite synthesized was tested up to 1300 °C and no reaction between the phases of the constituents is observed with the morphologies of the phases being retained. -- Abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)–yttria (20 wt%) nano composite (LaPO 4 –20%Y 2 O 3 ), has an average particle size of ∼70 nm after heat treatment of precursor at 600 °C. TG–DTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 °C. The TEM images of the composite show rod shape morphology of LaPO 4 in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 °C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.

  1. Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

    Science.gov (United States)

    Liu, Hongyuan; Guo, Min; Zhang, Yan

    2014-01-01

    Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

  2. Graphene nano-devices and nano-composites for structural, thermal and sensing applications

    Science.gov (United States)

    Yavari, Fazel

    In this dissertation we have developed graphene-based nano-devices for applications in integrated circuits and gas sensors; as well as graphene-based nano-composites for applications in structures and thermal management. First, we have studied the bandgap of graphene for semiconductor applications. Graphene as a zero-bandgap material cannot be used in the semiconductor industry unless an effective method is developed to open the bandgap in this material. We have demonstrated that a bandgap of 0.206 eV can be opened in graphene by adsorption of water vapor molecules on its surface. Water molecules break the molecular symmetries of graphene resulting in a significant bandgap opening. We also illustrate that the lack of bandgap in graphene can be used to our advantage by making sensors that are able to detect low concentrations of gas molecules mixed in air. We have shown that 1-2 layers of graphene synthesized by chemical vapor deposition enables detection of trace amounts of NO 2 and NH3 in air at room temperature and atmospheric pressure. The gas species are detected by monitoring changes in electrical resistance of the graphene film due to gas adsorption. The sensor response time is inversely proportional to the gas concentration. Heating the film expels chemisorbed molecules from the graphene surface enabling reversible operation. The detection limits of ~100 parts-per-billion (ppb) for NO2 and ~500 ppb for NH3 obtained using this device are markedly superior to commercially available NO2 and NH3 detectors. This sensor is fabricated using individual graphene sheets that are exquisitely sensitive to the chemical environment. However, the fabrication and operation of devices that use individual nanostructures for sensing is complex, expensive and suffers from poor reliability due to contamination and large variability from sample-to-sample. To overcome these problems we have developed a gas sensor based on a porous 3D network of graphene sheets called graphene foam

  3. Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

    International Nuclear Information System (INIS)

    Wang, Hua-Jie; Yu, Xue-Hong; Wang, Cai-Feng; Cao, Ying

    2013-01-01

    Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug

  4. Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

    International Nuclear Information System (INIS)

    Salih, A.M.; Mansor Ahmad; Nor Azowa Ibrahim; Rida Tajau; Wan Mohd Zin Wan Yunus

    2013-01-01

    Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4 ' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the T g was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

  5. Cooperative cytotoxic activity of Zn and Cu in bovine serum albumin-conjugated ZnS/CuS nano-composites in PC12 cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua-Jie, E-mail: wanghuajie972001@163.com; Yu, Xue-Hong; Wang, Cai-Feng; Cao, Ying, E-mail: caoying1130@sina.com [Henan Normal University, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, College of Chemistry and Chemical Engineering (China)

    2013-11-15

    Series of self-assembled and mono-dispersed bovine serum albumin (BSA)-conjugated ZnS/CuS nano-composites with different Zn/Cu ratios had been successfully synthesized by a combination method of the biomimetic synthesis and ion-exchange strategy under the gentle conditions. High-resolution transmission electron microscopy observation, Fourier transform infrared spectra and zeta potential analysis demonstrated that BSA-conjugated ZnS/CuS nano-composites with well dispersity had the hierarchical structure and BSA was a key factor to control the morphology and surface electro-negativity of final products. The real-time monitoring by atomic absorption spectroscopy and powder X-ray diffraction revealed that the Zn/Cu ratio of nano-composites could be controlled by adjusting the ion-exchange time. In addition, the metabolic and morphological assays indicated that the metabolic proliferation and spread of rat pheochromocytoma (PC12) cells could be inhibited by nano-composites, with the high anti-cancer activity at a low concentration (4 ppm). What were more important, Zn and Cu in nano-composites exhibited a positive cooperativity at inhibiting cancer cell functions. The microscope observation and biochemical marker analysis clearly revealed that the nano-composites-included lipid peroxidation and disintegration of membrane led to the death of PC12 cells. Summarily, the present study substantiated the potential of BSA-conjugated ZnS/CuS nano-composites as anti-cancer drug.

  6. Preparation of new series of poly(amide-imide) reinforced layer silicate nano composite containing N-trimellitimide-L-alanine

    International Nuclear Information System (INIS)

    Faghihi, K.; Soleimani, M.; Shabanian, M.

    2011-01-01

    A new poly(amide-imide)-montmorillonite series were generated through solution intercalation technique. Cloisite 20A was used as a modified montmorillonite for ample compatibility with the poly(amide-imide) (PAI) matrix. The PAI 5 chains were synthesized by the direct polycondensation reaction of N-trimellitylimido-L-alanine (3) with 4,4'-diamino diphenyl ether (4) in the presence of tryphenyl phosphites (TPP), CaCl 2 , pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nano composite films 5a-5d with (5-20 Wt%) silicate particles were characterized by Ftir spectroscopy, X-ray diffraction and scanning electron microscopy. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nano composites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis and water uptake measurements. (Author)

  7. Preparation of new series of poly(amide-imide) reinforced layer silicate nano composite containing N-trimellitimide-L-alanine

    Energy Technology Data Exchange (ETDEWEB)

    Faghihi, K.; Soleimani, M. [Polymer Research Laboratory, Department of Chemistry, Faculty of Science, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of); Shabanian, M., E-mail: k-faghihi@araku.ac.ir [Young Researches Club, Islamic Azad University, Arak Branch, Arak (Iran, Islamic Republic of)

    2011-07-01

    A new poly(amide-imide)-montmorillonite series were generated through solution intercalation technique. Cloisite 20A was used as a modified montmorillonite for ample compatibility with the poly(amide-imide) (PAI) matrix. The PAI 5 chains were synthesized by the direct polycondensation reaction of N-trimellitylimido-L-alanine (3) with 4,4'-diamino diphenyl ether (4) in the presence of tryphenyl phosphites (TPP), CaCl{sub 2}, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nano composite films 5a-5d with (5-20 Wt%) silicate particles were characterized by Ftir spectroscopy, X-ray diffraction and scanning electron microscopy. The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nano composites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis and water uptake measurements. (Author)

  8. Flow-induced crystallization of a nano composite of poly(butylene adipate-co-terephthalate)/montmorillonite

    International Nuclear Information System (INIS)

    Bonel, Alan B.; Rego, Bruna T.; Beatrice, Cesar A.G.; Marini, Juliano; Bretas, Rosario E.S.

    2011-01-01

    Poly(butylene adipate-co-terephthalate) (PBAT) with 5wt% of an organically modified montmorillonite with polar surfactant was prepared by melt blending in a co-rotational twin-screw extruder at 160 degree C. 100rpm and 1 kg/h. Both pure polymer and nano composite were characterized by wide measurements. The study of the flow-induced crystallization was also done by rheological measurements, monitoring the viscosity as a function of time. The nano clay's lamellas were intercalated in the polymer m loss moduli of the nano composite, at low frequencies, showed that the particles of the nano clay were well dispersed and distributed thru the PBAT matrix. Finally, the presence of the nano clay's particles reduced the induction tim crystals growth, due to the strong interactions with the PBAT chains. (author)

  9. Preparation and Characterization of Graphene-Based Magnetic Hybrid Nano composite

    International Nuclear Information System (INIS)

    Jashiela Wani Jusin; Madzlan Aziz

    2016-01-01

    Graphene-based magnetic hybrid nano composite has the advantage of exhibiting better performance as platform or supporting materials to develop novel properties of composite by increasing selectivity of the targeted adsorbate. The hybrid nano material was prepared by mixing and hydrolysing iron (II) and iron (III) salt precursors in the presence of GO dispersion through coprecipitation method followed by in situ chemical reduction of GO. The effect of weight loading ratio of Fe to GO (4:1, 2.5:1, 1:1 and 1:4) on structural properties of the hybrid nano materials was investigated. The presence of characteristic peaks in FTIR spectra indicated that GO has been successfully oxidized from graphite while the decrease in oxygenated functional groups and peaks intensity evidenced the formation of hybrid nano materials through the subsequent reduction process. The presence of characteristic peaks in XRD pattern denoted that magnetite nanoparticles disappeared at higher loading of GO. TEM micrograph showed that the best distribution of iron oxide particles on the surface of hybrid nano material occurred when the loading ratio of Fe to GO was fixed at 2:5 to 1. The reduced graphene oxide (RGO) sheets in the hybrid materials showed less wrinkled sheet like structure compared to GO due to exfoliation and reduction process during the synthesis. The layered morphology of GO degrades at higher concentrations of iron oxide. (author)

  10. Solution processed ternary blend nano-composite charge regulation layer to enhance inverted OLED performances

    Science.gov (United States)

    Kaçar, Rifat; Mucur, Selin Pıravadılı; Yıldız, Fikret; Dabak, Salih; Tekin, Emine

    2018-04-01

    Inverted bottom-emission organic light emitting diodes (IBOLEDs) have attracted increasing attention due to their exceptional air stability and applications in active-matrix displays. For gaining high IBOLED device efficiencies, it is crucial to develop an effective strategy to make the bottom electrode easy for charge injection and transport. Charge selectivity, blocking the carrier flow towards the unfavourable side, plays an important role in determining charge carrier balance and accordingly radiative recombination efficiency. It is therefore highly desirable to functionalize an interfacial layer which will perform many different tasks simultaneously. Here, we contribute to the hole-blocking ability of the zinc oxide/polyethyleneimine (ZnO:PEI) nano-composite (NC) interlayer with the intention of increasing the OLED device efficiency. With this purpose in mind, a small amount of 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi) was added as a hole-blocking molecule into the binary blend of ZnO and PEI solution. The device with a ternary ZnO:PEI:TPBi NC interlayer achieved a maximum current efficiency of 38.20 cd A-1 and a power efficiency of 34.29 lm W-1 with a luminance of 123 200 cd m-2, which are high performance parameters for inverted device architecture. The direct comparisons of device performances incorporating ZnO only, ZnO/PEI bilayers, and ZnO:PEI binary NC counterparts were also performed, which shed light on the origin of device performance enhancement.

  11. Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

    International Nuclear Information System (INIS)

    Debiagi, Flavia; Matsuda, Daniel K.M.; Marengo, Vitor A.; Vercelheze, Ana Elisa S.; Mali, Suzana

    2011-01-01

    The objectives of this work were to produce biodegradable trays based on cassava starch (native or modified by acid), sugarcane fibers and nano clay (sodium montmorillonite) and also to characterize the produced trays according to their density, tensile strength, X-ray diffraction and biodegradability. The trays were obtained by thermoforming into a hydraulic press coupled to a Teflon mold (18 x 23 cm) at 130 degree C/ 20 min and 100 bars of pressure. The peak related to the nano clay (2 = 7.1 o ) were not observed in XRD patterns of the trays, suggesting the formation of an exfoliated structure in the nano composite. The addition of modified starch increased tensile strength and density of the samples, and the addition of fibers and nano clays decreased the tensile strength of native and modified starch trays. The weight loss of trays was not affected by the starch type, however the addition of fibers increased the biodegradation and the addition of nano clays decreased. (author)

  12. An Overview on the Improvement of Mechanical Properties of Ceramics Nano composites

    International Nuclear Information System (INIS)

    Silvestre, J.; Brito, J. D.; Silvestre, N.

    2015-01-01

    Due to their prominent properties (mechanical, stiffness, strength, thermal stability), ceramic composite materials (CMC) have been widely applied in automotive, industrial and aerospace engineering, as well as in biomedical and electronic devices. Because monolithic ceramics exhibit brittle behaviour and low electrical conductivity, CMC_s have been greatly improved in the last decade. CMC_s are produced from ceramic fibres embedded in a ceramic matrix, for which several ceramic materials (oxide or non-oxide) are used for the fibres and the matrix. Due to the large diversity of available fibres, the properties of CMC_s can be adapted to achieve structural targets. They are especially valuable for structural components with demanding mechanical and thermal requirements. However, with the advent of nanoparticles in this century, the research interests in CMC_s are now changing from classical reinforcement (e.g., microscale fibres) to new types of reinforcement at nano scale. This review paper presents the current state of knowledge on processing and mechanical properties of a new generation of CMC_s: Ceramics Nano composites (CNC_s)

  13. Graphene–Noble Metal Nano-Composites and Applications for Hydrogen Sensors

    Directory of Open Access Journals (Sweden)

    Sukumar Basu

    2017-10-01

    Full Text Available Graphene based nano-composites are relatively new materials with excellent mechanical, electrical, electronic and chemical properties for applications in the fields of electrical and electronic devices, mechanical appliances and chemical gadgets. For all these applications, the structural features associated with chemical bonding that involve other components at the interface need in-depth investigation. Metals, polymers, inorganic fibers and other components improve the properties of graphene when they form a kind of composite structure in the nano-dimensions. Intensive investigations have been carried out globally in this area of research and development. In this article, some salient features of graphene–noble metal interactions and composite formation which improve hydrogen gas sensing properties—like higher and fast response, quick recovery, cross sensitivity, repeatability and long term stability of the sensor devices—are presented. Mostly noble metals are effective for enhancing the sensing performance of the graphene–metal hybrid sensors, due to their superior catalytic activities. The experimental evidence for atomic bonding between metal nano-structures and graphene has been reported in the literature and it is theoretically verified by density functional theory (DFT. Multilayer graphene influences gas sensing performance via intercalation of metal and non-metal atoms through atomic bonding.

  14. Thermal Properties, Structure and Morphology of Graphene Reinforced Polyethylene Terephthalate/ Polypropylene Nano composites

    International Nuclear Information System (INIS)

    Inuwa, I.M.; Hassan, A.; Shamsudin, S.A.

    2014-01-01

    In this work the thermal properties, structure and morphology of a blend of polyethylene terephthalate (PET) and polypropylene (PP) reinforced with graphene nano platelets (GNP) were investigated. A blend of PET/ PP (70/ 30 weight percent) compatibilized with styrene-ethylene-butylene-styrene grafted maleic anhydride triblock copolymer (10 phr) were fabricated by melt extrusion process in a twin screw extruder. The effective thermal conductivity of the nano composites increased as a function of the GNP concentration. More than 80 % increase in effective thermal conductivity was observed for the 7 phr reinforced sample compared to the neat blend. This observation was attributed to the development interconnected GNP sheets which formed heat conductive bridges that are suitable for maximum heat transfer. However, in the case of thermal stability which is a function of dispersibility of GNP in polymer matrix, the maximum increase was observed at 3 phr GNP loading which could be attributed to the uniform dispersion of GNPs in the matrix. It is explained that the GNP nano fillers migrated to the surface of matrix forming an effective oxygen barrier due to char formation. Morphological studies revealed uniform dispersion graphene in the polymer matrix at 3 phr GNP loading along with isolated instances of exfoliation of the graphene layers. (author)

  15. Synthesis and characterization of aluminium–alumina micro- and nano-composites by spark plasma sintering

    International Nuclear Information System (INIS)

    Dash, K.; Chaira, D.; Ray, B.C.

    2013-01-01

    Graphical abstract: The evolution of microstructure by varying the particle size of reinforcement in the matrix employing spark plasma sintering has been demonstrated here in Al–Al 2 O 3 system. An emphasis has been laid on varying the reinforcement particle size and evaluating the microstructural morphologies and their implications on mechanical performance of the composites. Nanocomposites of 0.5, 1, 3, 5, 7 volume % alumina (average size 2 O 3 micro- and nano-composites fabricated by spark plasma sintering. • Better matrix-reinforcement integrity in nanocomposites than microcomposites. • Spark plasma sintering method results in higher density and hardness values. • High density and hardness values of nanocomposites than microcomposites. • High dislocation density in spark plasma sintered Al–Al 2 O 3 composites. - Abstract: In the present study, an emphasis has been laid on evaluation of the microstructural morphologies and their implications on mechanical performance of the composites by varying the reinforcement particle size. Nanocomposites of 0.5, 1, 3, 5, 7 volume % alumina (average size 2 O 3 nancomposites respectively. Spark plasma sintering imparts enhanced densification and matrix-reinforcement proximity which have been corroborated with the experimental results

  16. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    OpenAIRE

    Abdalla, Soliman; Al-Marzouki, Fahad; Obaid, Abdullah; Gamal, Salah

    2016-01-01

    Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of...

  17. Effect of Alumina Addition to Zirconia Nano-composite on Low Temperature Degradation Process and Biaxial Strength

    Directory of Open Access Journals (Sweden)

    Moluk Aivazi

    2016-12-01

    Full Text Available Ceramic dental materials have been considered as alternatives to metals for dental implants application. In this respect, zirconia tetragonal stabilized with %3 yttrium, is of great importance among the ceramic materials for endosseous dental implant application. Because of its good mechanical properties and color similar to tooth. The aim and novelty of this study was to design and prepare Y-TZP nano-composite to reduce the degradation process at low temperature by alumina addition and maintaining submicron grain sized. Also, flexural strength of nano-composite samples was evaluated. Toward this purpose, alumina-Y-TZP nano-composites containing 0–30 vol% alumina (denoted as A-Y-TZP 0-30 were fabricated using α-alumina and Y-TZP nano-sized by sintering pressure less method. The synthesized samples were characterized using x-ray diffraction, field emission scanning electron microscopy equipped with energy dispersive x-ray spectroscopy techniques. Nano-composite samples with high density (≥96% and grain sized of ≤ 400 nm was obtained by sintering at 1270 °C for 170 min. After low temperature degradation test (LTD, A-Y-TZP20 and A-Y-TZP30 not showed monoclinic phase and the flexural strength in all of samples were higher than A-Y-TZP0. It was concluded that the grains were remained in submicron sized and A-Y-TZP20 and A-Y-TZP30 did not present biaxial strength reduction after LTD test.

  18. Interference of processing variables on the mechanical behavior of nano composites HDPE/clay; Interferencia das variaveis de processamento no comportamento mecanico de nanocompositos PEAD/argila

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa, R. [Universidade Federal do Piaui, Teresina, PI (Brazil); Souza, D.D.; Nobrega, K.C.; Araujo, E.M.; Melo, T.J. [Universidade Federal de Campina Grande - UAEMa Campina Grande, PB (Brazil)

    2010-07-01

    Nano composites were processed using the technique of melt intercalation, starting from a concentrated polar compatibilizer / organo clay (PE-g-MA / organo clay) prepared in an internal mixer. The concentrate was incorporated into the matrix of PEAD by two methods: (I) twin screw contrarrotational extruder and (II) twin screw corrotational extruder, using two thread profiles (ROS and 2KB90), after extrusion, the specimens of the extruded composites were injection molded. The diffraction of X-ray was used to analyze the degree of expansion of the clays prepared, and the degree of exfoliation of nano composites developed. The interference of processing variables on mechanical properties was studied by the behavior of the modulus and tensile strength of nano composite systems. Observed similar behavior in the use of thread (or 2KB90 ROS) of the nano composites, with a reduction in modulus and tensile strength. (author)

  19. Polypropylene Nano composites Obtained by In Situ Polymerization Using Metallocenes Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

    International Nuclear Information System (INIS)

    Zapata, P.; Quijada, R.

    2012-01-01

    Polypropylene nano composites containing silica nanospheres based on the sol-gel methods were produced via in situ polymerization using a rac-Et(Ind) 2 ZrCl 2 /methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind) 2 ZrCl 2 )/(MAO) directly into the reactor, and in route 2 the metallocenes rac-Et(Ind) 2 ZrCl 2 was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nano composites obtained by both routes had a slightly higher percent crystallinity and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nano composites obtained by the support system (route 2).

  20. Nano-composite of PtRu alloy electrocatalyst and electronically conducting polymer for use as the anode in a direct methanol fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Jongho Choi; Kyungwon Park; Hyekyung Lee; Youngmin Kim; Jaesuk Lee; Yungeun Sung [Kwangju Inst. of Science and Technology, Dept. of Materials Science and Engineering, Gwangju (Korea)

    2003-08-15

    Nano-composites comprised of PtRu alloy nanoparticles and an electronically conducting polymer for the anode electrode in direct methanol fuel cell (DMFC) were prepared. Two conducting polymers of poly(N-vinyl carbazole) and poly(9-(4-vinyl-phenyl)carbazole) were used for the nano-composite electrodes. Structural analyses were carried out using Fourier transform nuclear magnetic resonance spectroscopy, AC impedance spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Electrocatalytic activities were investigated by voltammetry and chronoamperometry in a 2 M CH{sub 3}OH/{sub 0.5} M H{sub 2}SO{sub 4} solution and the data compared with a carbon-supported PtRu electrode. XRD patterns indicated good alloy formation and nano-composite formation was confirmed by TEM. Electrochemical measurements and DMFC unit-cell tests indicate that the nano-composites could be useful in a DMFC, but its performance would be slightly lower than that of a carbon-supported electrode. The interfacial property between the PtRu-polymer nano-composite anode and the polymer electrolyte was good, as evidenced by scanning electron microscopy. For better performance in a DMFC, a higher electric conductivity of the polymer and a lower catalyst loss are needed in nano-composite electrodes. (Author)

  1. Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

    Science.gov (United States)

    Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

    2013-03-15

    Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

    Science.gov (United States)

    Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

    2017-09-01

    In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

  3. Preparation and characterization of functionalized cellulose nano crystals with methyl adipoyl chloride used to prepare chitosan grafting nano composite

    International Nuclear Information System (INIS)

    Mesquita, Joao Paulo de; Teixeira, Ivo F.; Donnici, Claudio L.; Pereira, Fabiano V.

    2011-01-01

    Cellulose nano crystals (CNCs) were prepared from eucalyptus pulp and functionalized with methyl adipoyl chloride. The nano materials were characterized by different techniques including FTIR, 1H NMR and XRD which showed that the functionalization occurs only on the surface of the nano structures without change in crystalline structure of the nanoparticles. The new-functionalized CNCs were used as reinforcement in the preparation of a nano composite with chitosan, through the formation of a covalent bond between the nano filler and matrix. Preliminary results of mechanical tests indicate an improvement in tensile strength and increase in deformation of chitosan. (author)

  4. Study of the morphology exhibited by exfoliated polyurethane/montmorillonite nano composites during in situ recovery tests

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Iaci M., E-mail: iaci@ctex.eb.br [Divisao Belica do Centro Tecnologico do Exercito. CTEx, Rio de Janeiro, RJ (Brazil); Orefice, Rodrigo L. [Universidade Federal de Minas Gerais Departamento de Metalurgia e Materiais. UFMG, Belo Horizonte, MG (Brazil)

    2011-07-01

    By using small-angle X-ray scattering, this study aims to examine the SM behavior of montmorillonite polyurethane nano composites. To investigate the phase morphology, a deformed specimen was placed on a heating stage mounted at the Synchrotron beamline; the shape recovery was measured during 15 min. As temperature increases, the crystalline fraction rapidly decreases. The degree of clay delamination within the matrix increases, disturbing the formation of hard and soft segments. Deformation induces changes in the phase proportion, increasing the disperse phase contribution. During in situ tests, the ratio between matrix and disperse phase reaches an equilibrium controlled by the temperature. (author)

  5. Magnetic nanoparticles based nano-composites: synthesis, contribution of the fillers dispersion and the chains conformation on the reinforcement properties

    International Nuclear Information System (INIS)

    Robbes, Anne-Sophie

    2011-01-01

    The mechanical properties of polymeric nano-composite films can be considerably enhanced by the inclusion of inorganic nanoparticles due to two main effects: (i) the local structure of fillers dispersion and (ii) the potential modification of the chains conformation and dynamics in the vicinity of the filler/polymer interface. However, the precise mechanisms which permit to correlate these contributions at nano-metric scale to the macroscopic mechanical properties of the materials are actually poorly described. In such a context, we have synthesized model nano-composites based on magnetic nanoparticles of maghemite γ-Fe 2 O 3 (naked or grafted with a polystyrene (PS) corona by radical controlled polymerization) dispersed in a PS matrix, that we have characterized by combining small angle scattering (X-Ray and neutron) and transmission electronic microscopy. By playing on different parameters such as the particle size, the concentration, or the size ratio between the grafted chains and the ones of the matrix in the case of the grafted fillers, we have obtained nano-composite films a large panel of controlled and reproducible controlled filler structures, going from individual nanoparticles or fractal aggregates up to the formation of a connected network of fillers. By applying an external magnetic field during the film processing, we succeeded in aligning the different structures along the direction of the field and we obtained materials with remarkable anisotropic reinforcement properties. The conformation of the chains of the matrix, experimentally determined thanks to the specific properties of neutron contrast of the system, is not affected by the presence of the fillers, whatever their confinement, the dispersion the fillers or their chemical state surface. The alignment of the fillers along the magnetic field has allowed us to describe precisely the evolution of the reinforcement modulus of the materials with the structural reorganization of the fillers and

  6. P(AN-MMA)/TiO_2 Nano-composite Polymer Electrolyte by in-situ Polymerization

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Introduction With the development of portable electric devices,polymer lithium ion batteries (PLiBs) have been widely used as the power sources because of their high energy density and safe property[1].P(AN-MMA) copolymer is a kind of cheap macromolecules easily dissolving in the polar solvents such as carbonate,it has been applied as gel polymer electrolyte in PLiBs.Here we prepare a kind of highly conductive nano-composite polymer electrolytes using the P(AN-MMA) copolymer incorporated with TiO2 nan...

  7. Removal of Dibenzothiophene Using Activated Carbon/γ-Fe2O3 Nano-Composite: Kinetic and Thermodynamic Investigation of the Removal Process

    Directory of Open Access Journals (Sweden)

    Maryam Fayazi

    2015-12-01

    Full Text Available In the present study, removal of dibenzothiophene (DBT from model oil (n-hexane was investigated using magnetic activated carbon (MAC nano-composite adsorbent. The synthesized nano-composite was characterized by FT-IR, FE-SEM, BET and VSM techniques. The MAC nano-composite exhibited a nearly superparamagnetic property with a saturation magnetization (Ms of 29.2 emu g-1, which made it desirable for separation under an external magnetic field. The magnetic adsorbent afforded a maximum adsorption capacity of 38.0 mg DBT g-1 at the optimized conditions (adsorbent dose, 8 g l-1; contact time, 1 h; temperature, 25 °C. Langmuir, Freundlich and Temkin isotherm models were used to fit equilibrium data for MAC nano-composite. Adsorption process could be well described by the Langmuir model. Kinetic studies were carried out and showed the sorption kinetics of DBT was best described by a pseudo-second-order kinetic model. In addition, the MAC nano-composite exhibited good capability of recycling to adsorb DBT in gasoline deep desulfurization.

  8. Synthesis and characterization of water-soluble and conducting sulfonated polyaniline/para-phenylenediamine-functionalized multi-walled carbon nanotubes nano-composite

    International Nuclear Information System (INIS)

    Xu Jun; Yao Pei; Li Xuan; He Fei

    2008-01-01

    Water-soluble and conducting sulfonated polyaniline (SPAN)/phenylamine groups contained MWNTs (p-MWNTs) nano-composite were synthesized by in situ oxidation polymerization followed by sulfonation and hydrolysis. TEM, Raman spectroscopy, FTIR, XPS, TGA and standard four-probe methods were employed to characterize morphology, chemical structure and performance of the nano-composite. The results show that phenylamine groups are grafted on the surface of p-MWNTs via amide bond and oxidized phenylamine groups initiate polyaniline polymerized on the surface of p-MWNTs. SPAN chains covalently attached to p-MWNTs render p-MWNTs compatibility with SPAN matrix and lead to SPAN/p-MWNTs nano-composite highly soluble and stable in water. Improved thermal stability illuminate existence of a new phase in the nano-composite where there is chemical interaction between p-MWNTs and SPAN coatings. Owing to incorporation of p-MWNTs conductivity of the nano-composite at room temperature is increased by about two orders of magnitude over neat SPAN

  9. Functionalized Multi walled Carbon Nano tubes-Reinforced Viny lester/Epoxy Blend Based Nano composites: Enhanced Mechanical, Thermal, and Electrical Properties

    International Nuclear Information System (INIS)

    Praharaj, A. P.; Behera, D.; Bastia, T. K.; Rout, A. K.

    2015-01-01

    This paper presents a study on the mechanical, thermal, and electrical characterization of a new class of low cost multiphase nano composites consisting of Vinyl ester resin/epoxy (VER/EP) blend (40:60 w/w) reinforced with amine functionalized multi walled carbon nano tubes (f-MWCNTs). Five different sets of VER/EP nano composites are fabricated with addition of 0, 1, 3, 5, and 7 wt.% of f-MWCNTs. A detailed investigation of mechanical properties like tensile strength, impact strength, Young’s modulus, and hardness, thermal properties like thermogravimetric analysis (TGA) and thermal conductivity, electrical properties like dielectric strength, dielectric constant, and electrical conductivity, and corrosive and swelling properties of the nano composites has been carried out. Here, we report significant improvement in all the above properties of the fabricated nano composites with nano filler (f-MWCNTs) addition compared to the virgin blend (0 wt. nano filler loading). The properties are best observed in case of 5 wt.% nano filler loading with gradual deterioration thereafter which may be due to the nucleating tendency of the nano filler particles. Thus the above nano composites could be a preferable candidate for a wide range of structural, thermal, electrical, and solvent based applications.

  10. Novel Preparation of Nano-Composite CuO-Cr2O3 Using Ctab-Template Method and Efficient for Hydrogenation of Biomass-Derived Furfural

    Science.gov (United States)

    Yan, Kai; Wu, Xu; An, Xia; Xie, Xianmei

    2013-02-01

    A simple route to fabricate nano-composite oxides CuO-Cr2O3 using hexadecyltrimethylammonium bromide (CTAB)-templated Cu-Cr hydrotalcite as the precursor is presented. This novel method is based on CTAB-templating effect for mesostructure directing and using the cheap metal nitrate, followed by removal of CTAB. It was indicated that the nano-composite CuO-Cr2O3 was formed during the removal of CTAB. X-ray diffraction (XRD) and transitional electronic microscopy (TEM) revealed nice nano-composite oxides CuO-Cr2O3 were formed with high crystallinity. N2 adsorption and desorption indicated that a high surface area of 170.5 m2/g with a pore size of 2.7 nm of the nano-composite CuO-Cr2O3 was facilely resulted. The as-synthesized nano-composite oxides CuO-Cr2O3 display good catalytic activities for hydrogenation of furfural to furfuryl alcohol, whereas 86% selectivity was achieved at 75% conversion of furfural.

  11. One-Pot Hydrothermal Synthesis of Magnetite Prussian Blue Nano-Composites and Their Application to Fabricate Glucose Biosensor

    Directory of Open Access Journals (Sweden)

    Ezzaldeen Younes Jomma

    2016-02-01

    Full Text Available In this work, we presented a simple method to synthesize magnetite Prussian blue nano-composites (Fe3O4-PB through one-pot hydrothermal process. Subsequently, the obtained nano-composites were used to fabricate a facile and effective glucose biosensor. The obtained nanoparticles were characterized using transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, UV-vis absorbance spectroscopy, cyclic voltammetry and chronoamperometry. The resultant Fe3O4-PB nanocomposites have magnetic properties which could easily controlled by an external magnetic field and the electro-catalysis of hydrogen peroxide. Thus, a glucose biosensor based on Fe3O4-PB was successfully fabricated. The biosensor showed super-electrochemical properties toward glucose detection exhibiting fast response time within 3 to 4 s, low detection limit of 0.5 µM and wide linear range from 5 µM to 1.2 mM with sensitivity of 32 µA∙mM−1∙cm−2 and good long-term stability.

  12. Digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing

    Science.gov (United States)

    Jiang, Wei; He, Xiaoning; Liu, Hongzhong; Yin, Lei; Shi, Yongsheng; Ding, Yucheng

    2014-11-01

    In this article, we report on the digital selective fabrication of micro/nano-composite structured TiO2 nanorod arrays by laser direct writing. The pattern of TiO2 nanorod arrays can be easily designed and fabricated by laser scanning technology integrated with a computer-aided design system, which allows a high degree of freedom corresponding to the various pattern design demands. The approach basically involves the hydrothermal growth of TiO2 nanorod arrays on a transparent conductive substrate, the micropattern of TiO2 nanorod arrays and surface fluorination treatment. With these micro/nano-composite TiO2 nanorod array based films, we have demonstrated superhydrophilic patterned TiO2 nanorod arrays with rapid water spreading ability and superhydrophobic patterned TiO2 nanorod arrays with an excellent droplet bouncing effect and a good self-cleaning performance. The dynamic behaviours of the water droplets observed on the patterned TiO2 nanorod arrays were demonstrated by experiments and simulated by a finite element method. The approaches we will show are expected to provide potential applications in fields such as self-cleaning, surface protection, anticrawling and microfluidic manipulation.

  13. Significantly Elevated Dielectric and Energy Storage Traits in Boron Nitride Filled Polymer Nano-composites with Topological Structure

    Science.gov (United States)

    Feng, Yefeng; Zhang, Jianxiong; Hu, Jianbing; Li, Shichun; Peng, Cheng

    2018-03-01

    Interface induced polarization has a prominent influence on dielectric properties of 0-3 type polymer based composites containing Si-based semi-conductors. The disadvantages of composites were higher dielectric loss, lower breakdown strength and energy storage density, although higher permittivity was achieved. In this work, dielectric, conductive, breakdown and energy storage properties of four nano-composites have been researched. Based on the cooperation of fluoropolymer/alpha-SiC layer and fluoropolymer/hexagonal-BN layer, it was confirmed constructing the heterogeneous layer-by-layer composite structure rather than homogeneous mono-layer structure could significantly reduce dielectric loss, promote breakdown strength and increase energy storage density. The former worked for a larger dielectric response and the latter layer acted as a robust barrier of charge carrier transfer. The best nano-composite could possess a permittivity of 43@100 Hz ( 3.3 times of polymer), loss of 0.07@100 Hz ( 37% of polymer), discharged energy density of 2.23 J/cm3@249 kV/cm ( 10 times of polymer) and discharged energy efficiency of 54%@249 kV/cm ( 5 times of polymer). This work might enlighten a facile route to achieve the promising high energy storage composite dielectrics by constructing the layer-by-layer topological structure.

  14. The Degradation of Mechanical Properties in Halloysite Nano clay-Polyester Nano composites Exposed in Seawater Environment

    International Nuclear Information System (INIS)

    Saharudin, M.S.; Saharudin, M. Sh.; Wei, J.; Shyha, I.; Inam, F.

    2016-01-01

    Polyester based polymers are extensively used in aggressive marine environments; however, inadequate data is available on the effects of the seawater on the polyester based nano composites mechanical properties. This paper reports the effect of seawater absorption on the mechanical properties degradation of halloysite nano clay-polyester nano composites. Results confirmed that the addition of halloysite nano clay into polyester matrix was found to increase seawater uptake and reduce mechanical properties compared to monolithic polyester. The maximum decreases in microhardness, tensile and flexural properties, and impact toughness were observed in case of 1 wt% nano clay. The microhardness decreased from 107 HV to 41.7 HV (61% decrease). Young s modulus decreased from 0.6 GPa to 0.4 GPa (33% decrease). The flexural modulus decreased from 0.6 GPa to 0.34 GPa (43% decrease). The impact toughness dropped from 0.71 kJ/m"2 to 0.48 kJ/m"2 (32% decrease). Interestingly, the fracture toughnessκ_1C increased with the addition of halloysite nano clay due to the plasticization effect of the resin matrix. SEM images revealed the significant reduction in mechanical properties in case of 1 wt% reinforcement which is attributed to the degradation of the nano clay-matrix interface influenced by seawater absorption and agglomeration of halloysite nano clay.

  15. Effect of stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites

    Science.gov (United States)

    Papanicolaou, G. C.; Pappa, E. J.; Portan, D. V.; Kotrotsos, A.; Kollia, E.

    2018-02-01

    The aim of the present investigation was to study the effect of both the stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites. Four types of multilayered hybrid nanocomposites were manufactured and tested: Nitinol- CNTs (carbon nanotubes)- Acrylic resin; Nitinol- Acrylic resin- CNTs; Surface treated Nitinol- CNTs- Acrylic resin and Surface treated Nitinol- Acrylic resin- CNTs. Surface treatment of Nitinol plies was realized by means of the electrochemical anodization. Surface topography of the anodized nitinol sheets was investigated through Scanning Electron Microscopy (SEM). It was found that the overall thermal response of the manufactured multilayered nano-composites was greatly influenced by both the anodization and the stacking sequence. A theoretical model for the prediction of the overall thermal conductivity has been developed considering the nature of the different layers, their stacking sequence as well as the interfacial thermal resistance. Thermal conductivity and Differential Scanning Calorimetry (DSC) measurements were conducted, to verify the predicted by the model overall thermal conductivities. In all cases, a good agreement between theoretical predictions and experimental results was found.

  16. Fe{sub 2}O{sub 3}-Poly-pyrrole hybrid nano-composite materials for super-capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Mallouki, M.; Tran-Van, F.; Sarrazin, C.; Chevrot, C. [Cergy-Pontoise Univ., Lab. de Physicochimie des Polymeres et des Interfaces (LPPI), EA 2528 95 (France); Fauvarque, J.F. [CNAM, Lab. d' Electrochimie Industrielle, 75 - Paris (France); Simon, P. [Universite Paul Sabatier, CIRIMAT-LCMIE, UMR 5085, 31 - Toulouse (France); De, A. [Saha Institute of Nuclear Physics, Calcutta (India)

    2004-07-01

    Fe{sub 2}O{sub 3}-Poly-pyrrole hybrid nano-composite materials chemically synthesized from colloid particles of iron oxide in aqueous solution have been processed to realize electrode materials for super-capacitor applications. The performances have been evaluated by cyclic voltammetry and galvano-static techniques in a three-electrode cell. The capacitance of Fe{sub 2}O{sub 3}-PPy hybrid nano-composite doped with para-toluene-sulfonate reaches 47 mAh/g in PC/NEt{sub 4}BF{sub 4} with a good stability during cycling (loss of 3% after 1000 cycles). Transmission Electronic Microscopy indicates a porous nano-structure with spherical particles in a range of 400-500 nm which ensures a good accessibility of the electrolyte in the bulk of the electro-active hybrid material. Preliminary studies with room temperature ionic liquid show promising results since the specific capacitance reaches 427 F/g in 1- ethyl-3-methyl-imidazolium bis((tri-fluoro-methyl)sulfonyl)amide (EMITFSI). (authors)

  17. Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples.

    Science.gov (United States)

    Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Goud, D Raghavender; Dubey, D K; Pardasani, Deepak

    2015-05-15

    Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200mL of water sample for 20min. followed by methanol/chloroform extraction produced average to good recoveries (27-94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11ngmL(-1) and 0.19ngmL(-1) respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

    International Nuclear Information System (INIS)

    Ismail, A.R.; Vejayakumaran, P.

    2012-01-01

    Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.

  19. Microfluidic active mixers employing ultra-high aspect-ratio rare-earth magnetic nano-composite polymer artificial cilia

    International Nuclear Information System (INIS)

    Rahbar, Mona; Gray, Bonnie L; Shannon, Lesley

    2014-01-01

    We present a new micromixer based on highly magnetic, flexible, high aspect-ratio, artificial cilia that are fabricated as individual micromixer elements or in arrays for improved mixing performance. These new cilia enable high efficiency, fast mixing in a microchamber, and are controlled by small electromagnetic fields. The artificial cilia are fabricated using a new micromolding process for nano-composite polymers. Cilia fibers with aspect-ratios as high as 8:0.13 demonstrate the fabrication technique's capability in creating ultra-high aspect-ratio microstructures. Cilia, which are realized in polydimethylsiloxane doped with rare-earth magnetic powder, are magnetized to produce permanent magnetic structures with bidirectional deflection capabilities, making them highly suitable as mixers controlled by electromagnetic fields. Due to the high magnetization level of the polarized nano-composite polymer, we are able to use miniature electromagnets providing relatively small magnetic fields of 1.1 to 7 mT to actuate the cilia microstructures over a very wide motion range. Mixing performances of a single cilium, as well as different arrays of multiple cilia ranging from 2 to 8 per reaction chamber, are characterized and compared with passive diffusion mixing performance. The mixer cilia are actuated at different amplitudes and frequencies to optimize mixing performance. We demonstrate that more than 85% of the total volume of the reaction chamber is fully mixed after 3.5 min using a single cilium mixer at 7 mT compared with only 20% of the total volume mixed with passive diffusion. The time to achieve over 85% mixing is further reduced to 70 s using an array of eight cilia microstructures. The novel microfabrication technique and use of rare-earth permanently-magnetizable nano-composite polymers in mixer applications has not been reported elsewhere by other researchers. We further demonstrate improved mixing over other cilia micromixers as enabled by the high

  20. Carbon nanoparticle doped micro-patternable nano-composites for wearable sensing applications (Conference Presentation)

    Science.gov (United States)

    Khosla, Ajit

    2017-04-01

    This talk focuses on preparation, characterization and micropatterning of electrically conducting KETJENBLACK carbon black nanoparticle (80 nm-diameter) doped Polydimethylsiloxane (PDMS) by employing extrusion mixing. Previously, we had reported fabrication of various micropatternable nanocomposites for wearable sensing applications vis solvent assisted ultrasonic mixing technique[1-16] . Extrusion mixing has an advantage as no organic solvents are used and homogenous dispersion of carbon nanoparticles is observed, which is confirmed by SEM analysis. The developed nanocomposite can be micropatterened using standard microfabrication techniques. It is also observed that percolation threshold occurs at 0.51 wt% of carbon nanoparticles in polymer matrix. Examples of developed nano-composites for wearable sensing applications for precision medicine will also be discussed. References: 1.http://summit.sfu.ca/item/12017 A. Khosla. Micropatternable multifunctional nanocomposite polymers for flexible soft MEMS applications. Diss. Applied Science: School of Engineering Science, 2011. 2. A. Khosla ; B. L. Gray; Fabrication of multiwalled carbon nanotube polydimethylsiloxne nanocomposite polymer flexible microelectrodes for microfluidics and MEMS. Proc. SPIE 7642, Electroactive Polymer Actuators and Devices (EAPAD) 2010, 76421V (April 09, 2010); doi:10.1117/12.847292. 3. Ang Li ; Ajit Khosla ; Connie Drewbrook ; Bonnie L. Gray; Fabrication and testing of thermally responsive hydrogel-based actuators using polymer heater elements for flexible microvalves. Proc. SPIE 7929, Microfluidics, BioMEMS, and Medical Microsystems IX, 79290G (February 14, 2011); doi:10.1117/12.873197. 4. Khosla, A. and Gray, B. L. (2010), Preparation, Micro-Patterning and Electrical Characterization of Functionalized Carbon-Nanotube Polydimethylsiloxane Nanocomposite Polymer. Macromol. Symp., 297: 210-218. doi:10.1002/masy.200900165 5. A. Khosla ; D. Hilbich ; C. Drewbrook ; D. Chung ; B. L. Gray; Large

  1. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    Directory of Open Access Journals (Sweden)

    Soliman Abdalla

    2016-02-01

    Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown performance is a character of polyimide (PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  2. SYNTHESIS AND CORROSION PROTECTION BEHAVIOR OF EPOXYTiO2-MICACEOUS IRON OXIDE NANO - COMPOSITE COATING ON St-37

    Directory of Open Access Journals (Sweden)

    M. R. Khorram

    2016-03-01

    Full Text Available The micro layers micaceous iron oxide and nano-TiO 2 were incorporated into the epoxy resin by mechanical mixing and sonication process. Optical micrographs showed that the number and diameter size of nanoparticle agglomerates were decreased by sonication. The structure and composition of the nanocomposite was determined using transmission electron microscopy which showed the presence of dispersed nano-TiO 2 in the polymer matrix. The anticorrosive properties of the synthesized nano-composites coating were investigated using salt spray, electrochemical impedance spectroscopy and polarization measurement. The EIS results showed that coating resistance increased by addition of micaceous iron oxide micro layers and nano-TiO 2 particles to the epoxy coatings. It was observed that higher corrosion protection of nanocomposite coatings obtained by the addition of 3 %wt micaceous iron oxide and 4%wt nano-TiO 2 into epoxy resin.

  3. Rare-earth element doped Si3N4/SiC micro/nano-composites-RT and HT mechanical properties

    Czech Academy of Sciences Publication Activity Database

    Lojanová, Š.; Tatarko, P.; Chlup, Zdeněk; Hnatko, M.; Dusza, J.; Lenčéš, Z.; Šajgalík, P.

    2010-01-01

    Roč. 30, č. 9 (2010), s. 1931-1944 ISSN 0955-2219 Institutional research plan: CEZ:AV0Z20410507 Keywords : Si3N4 * SiC * Nano-composites * Fracture toughness * Hardness * Strength * Creep Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.574, year: 2010

  4. SiO2@FeSO4 nano composite: A recoverable nano-catalyst for eco-friendly synthesis oximes of carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Mostafa Karimkoshteh

    2016-01-01

    Full Text Available Various aldoximes and ketoximes synthesis of corresponding aldehydes and ketones in the presence of SiO2@FeSO4 nano composite as recoverable nano catalyst and NH2OH·HCl. The SiO2@FeSO4 nano composite system was carried out between 10 to 15 min in oil bath (70-80 °C under solvent-free condition in excellent yields in addition this protocol can be used for industrial scales. This method offers some advantages in term of clean reaction conditions, easy work-up procedure, short reaction time, applied to convert α-diketones to α-diketoximes (as longer than other carbonyl compounds, α,β-unsaturated aldehydes and ketones to corresponding oximes and suppression of any side product. So we think that NH2OH•HCl/SiO2@FeSO4 nano composite system could be considered a new and useful addition to the present methodologies in this area. Structure of products and nano composite elucidation was carried out by 1H NMR, 13C NMR, FT-IR, scanning electron microscopy (SEM.

  5. Sintering of Cu–Al2O3 nano-composite powders produced by a thermochemical route

    Directory of Open Access Journals (Sweden)

    MARIJA KORAC

    2007-11-01

    Full Text Available This paper presents the synthesis of nano-composite Cu–Al2O3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu–Al2O3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM coupled with energy dispersive spectroscopy (EDS, differenttial thermal and thermogravimetric (DTA–TGA analysis and X-ray diffraction (XRD analysis. The size of the produced powders was 20–50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al2O3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu–Al2O3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties.

  6. In situ intercalative polymerization of poly (ε-caprolactone)/ 12-amino lauric acid-modified clay nano composites

    International Nuclear Information System (INIS)

    Reyes, Larry; Monserate, Juvy J.; Sumera, Florentino

    2013-01-01

    Polymer/layered silicate nano composites were prepared by in situ intercalative polymerization method from from ε-caprolactone (ε-CL) and 12-amino lauric acid modified montmorillonite (AMMT). The organo-modified clay was investigated for its capacity to facilitate ring-opening polymerization of ε-caprolactone within its silicate layers. The effect of varying the organo-modified clay loading (5%, 10% and 15% by weight) on the molecular weight of the poly (ε-caprolactone) (PCL) product was assessed by gel-permeation chromatography. The molecular weight of the polymer with different clay loadings ranged from ∼30,000 g/mo to ∼70,000 g/mol, where the 10% loading produced the highest molecular weight. Fourier Transform infrared (FTIR), and 1 H and 13 C Nuclear Magnetic Resonance (NMR) Spectroscopy were conducted to probe the composition of the polymer and the catalytic activity of AMMT to polymerize ε-CL. FTIR analyses showed two medium intensity and narrow CO-O stretching vibrations for the PCL products at around 1240 cm-1 and 1160 cm-1, which are attributed to ester skeletal backbone. 1 HNMR spectroscopic analysis revealed signals at 4.07 ppm and 3.66 ppm which can be attributed to εmethylene of caprolactone and methyl of ending ester group, respectively. The formation of the nano composites were assessed by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), XRD analyses showed a broadening and disappearance of diffraction peak of AMMT in the nana composite which may indicate the formation of the intercalated and partially exfoliated PCVL/AMMT nana composites. TEM observations corroborated the presence of intercalated and exfoliated layers of AMMT after polymerization. The present work demonstrates that AMMT can be used as an alternative g reen catalyst's for the production of biodegradable polymers, where the in situ intercalative polymerization was employed as a direct method of preparing polymer/layered silicates (author)

  7. Copper nano composites functionalized by bis-benzimidazole diamide ligand: Effect of size, co-anion dependent conductivity and band gap studies

    International Nuclear Information System (INIS)

    Singla, Manisha; Mohapatra, Subash Chandra; Ahmad, Sharif

    2012-01-01

    Copper (I) and copper (II) nano composites capped with a bis-benzimidazole diamide ligand were prepared by reverse micelle method and characterized using CHNS, FTIR, 1 H NMR, TEM and DLS studies. All particles were spherical ranging between 10 and 70 nm. They displayed a quasi reversible redox wave due to the Cu (II)/Cu (I) reduction process. The E g1 ′ values shift anodically as NO 3 − − − . Electrochemical HOMO and LUMO band gap (E g1 ′ ) for the nano composites were +1.80 (NO 3 − ), +2.80 (Cl − ) and +4.10 (SCN − ) eV, respectively. However, the optical band gap (E g1 ) for the nano composites was calculated from their absorption edges and lie between 1.77 and 4.13 eV. Fluorescence studies reveal that nano composites in themselves behave as an enhancer and quencher in respect to ligand, Quantum yield (φ) is varying from 0.008 to 0.02 photon. The activation energies range from 34 to 54 kJ mol −1 and are quite low in comparison to that of the free bis-benzimidazole diamide ligand (137 kJ mol −1 ). The lower activation energies further re-emphasize the nano size of these composites. At room temperature, the dc conductivity lies between 1 × 10 −4 –9.33 × 10 −4 S cm −1 [NO 3 − > SCN − > Cl − ] indicating them to be on the semiconductor insulator interface. The dielectric constant, dielectric loss and the ac conductivity were measured for all nano at room temperature and below the room temperature for the nano composite containing nitrate as co-anion. The conductivity was found to follow the correlated barrier hopping (CBH) mechanism; the exponent factor (s) varies from 0.5 to 1. -- Highlights: ► Nano composites of copper, capped by bis benzimidazole diamide ligand. ► Such copper nano composites have not been used in conductivity studies before. ► Conductance studies for these thus make this work unique. ► The dc conductivity of these composites is much higher than normal.

  8. Gamma radiation effects on nano composites of Ag nanoparticles in Zn O matrices; Efectos de la radiacion gamma en nanocompositos de nanoparticulas de Ag en matrices de ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Villasenor C, L. S.

    2015-07-01

    The study of gamma radiation effects in nano composites of silver nanoparticles in a Zn O matrix has been performed in this work. First, silver nanoparticles (AgNPs) were synthesized by colloidal methods, with two different mean average sizes, 48 nm and 24 nm respectively. These nanoparticles were characterized by transmission electron microscopy (Tem) and UV-Vis spectroscopy (UV-Vis). Then, with the synthesized AgNPs, nano composites in a matrix of Zn O were prepared. The first nano composite was prepared with the 48 nm AgNPs at 9.5 weight % of silver (Ag) and the second nano composite with the 24 nm nanoparticles at 1.0 weight % of Ag. Both nano composites were analyzed by scanning electron microscopy (Sem). The formation of the Zn O phase in the nano composite was corroborated through X-ray diffraction analysis. It was observed that the presence of AgNPs during the formation of the AgNPs/Zn O nano composite modified the size and morphology of the structures obtained compared to those of the pure Zn O without nanoparticles, however both exhibit a radial structure. Then, the nano composite at 9.5 weight % of Ag was irradiated with gamma rays at doses of 1, 20 and 50 kGy. Samples were analyzed by Sem and the Bet technique, before and after being irradiated, in order to determine the effect of gamma radiation in the morphology, porosity and surface area of the studied material. Even when there are changes in porosity and Surface area, this difference is not very significant for some applications, however it will have to be considered during the design of a specific application of the nano composites. On the other hand, no morphology modifications were identified on the samples irradiated at the studied doses, with the electron microscopy techniques used. (Author)

  9. Content

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    secondary levels. In subject matter didactics, the question of content is more developed, but it is still mostly confined to teaching on lower levels. As for higher education didactics, discussions on selection of content are almost non-existent on the programmatic level. Nevertheless, teachers are forced...... curriculum, in higher education, and to generate analytical categories and criteria for selection of content, which can be used for systematic didactical reflection. The larger project also concerns reflection on and clarification of the concept of content, including the relation between content at the level......Aim, content and methods are fundamental categories of both theoretical and practical general didactics. A quick glance in recent pedagogical literature on higher education, however, reveals a strong preoccupation with methods, i.e. how teaching should be organized socially (Biggs & Tang, 2007...

  10. Polyethylene ionomer-based nano-composite foams prepared by a batch process and MuCell injection molding

    International Nuclear Information System (INIS)

    Hayashi, Hidetomo; Mori, Tomoki; Okamoto, Masami; Yamasaki, Satoshi; Hayami, Hiroshi

    2010-01-01

    To understand the correlation between foamability and melt rheology of polyethylene-based ionomers having different degrees of the neutralization and corresponding nano-composites, we have conducted the foam processing via a batch process in an autoclave and microcellular foam injection molding (FIM) process using the MuCell technology. We have discussed the obtainable morphological properties in both foaming processes. All cellular structures were investigated by using field emission scanning electron microscopy. The competitive phenomenon between the cell nucleation and the cell growth including the coalescence of cell was discussed in light of the interfacial energy and the relaxation rate as revealed by the modified classical nucleation theory and rheological measurement, respectively. The FIM process led to the opposite behavior in the cell growth and coalescence of cell as compared with that of the batch process, where the ionic cross-linked structure has significant contribution to retard the cell growth and coalescence of cell. The mechanical properties of the structural foams obtained by FIM process were discussed.

  11. Design of thermoelectrically highly efficient Heusler compounds using phase separations and nano-composites under an economic point of view

    Science.gov (United States)

    Balke, Benjamin

    Half-Heusler (HH) compounds are one of the most promising candidates for thermoelectric materials for automotive and industrial waste heat recovery applications. In this talk, I will give an overview about our recent investigations of phase separations in HH thermoelectrics, focusing on the ternary system TiNiSn-ZrNiSn-HfNiSn. I will show how we adapted this knowledge to design a p-type HH compound which exhibits a ZT that is increased by 130% compared to the best published bulk p-type Heusler. I will also present how we used the phase separation to design thermoelectric highly efficient nano-composites of different single-phase materials. Since the price for Hafnium doubled within the last year, our research focused on the design of HH compounds without Hafnium. I will present a very recent calculation on ZT per Euro and efficiency per Euro for various materials followed by our latest very promising results for n-type Heusler compunds without Hafnium resulting in 20 times higher ZT/Euro values. These results strongly underline the importance of phase separations as a powerful tool for designing highly efficient materials for thermoelectric applications that fulfill the industrial demands for a thermoelectric converter. The author gratefully acknowledges financial support by the thermoHEUSLER2 Project (Project No. 19U15006F) of the German Federal Ministry of Economics and Technology (BMWi).

  12. High photocatalytic degradation activity of the polyvinyl chloride (PVC)-vitamin C (VC)-TiO{sub 2} nano-composite film

    Energy Technology Data Exchange (ETDEWEB)

    Yang Changjun; Gong Chuqing; Peng Tianyou [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Deng Kejian [Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education, South-Central University for Nationalities, Wuhan 430074 (China); Zan Ling, E-mail: irlab@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2010-06-15

    A novel photodegradable polyvinyl chloride (PVC)-vitamin C (VC)-TiO{sub 2} nano-composite film was prepared by embedding VC modified nano-TiO{sub 2} photocatalyst into the commercial PVC plastic. The solid-phase photocatalytic degradation behavior of PVC-VC-TiO{sub 2} nano-composite film under UV light irradiation was investigated and compared with those of the PVC-TiO{sub 2} film and the pure PVC film, with the aid of UV-Vis spectroscopy, scanning electron microscopy (SEM), weight loss monitoring, and X-ray diffraction spectra (XRD). The results show that PVC-VC-TiO{sub 2} nano-composite film has a high photocatalytic activity; the photocatalytic degradation rate of it is two times higher than that of PVC-TiO{sub 2} film and fifteen times higher than that of pure PVC film. The optimal mass ratio of VC to TiO{sub 2} is found to be 0.5. The mechanism of enhancing photocatalytic activity is attributed to the formation of a Ti{sup IV}-VC charge-transfer complex with five-member chelate ring structure and a rapid photogenerated charge separation is thus achieved.

  13. Corrosion Behavior and Microhardness of Ni-P-SiO2-Al2O3 Nano-composite Coatings on Magnesium Alloy

    Science.gov (United States)

    Sadreddini, S.; Rahemi Ardakani, S.; Rassaee, H.

    2017-05-01

    In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on AZ91HP magnesium alloy. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by energy-dispersive analysis of x-ray (EDX), and the crystalline structure of the coating was examined by x-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5 wt.% NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/Land 14 g/LAl2O3 led to the lowest corrosion rate ( i corr = 1.3 µA/cm2), the most positive E corr and maximum microhardness (496 VH). Furthermore, Ni-P-SiO2-Al2O3 nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance.

  14. Synthesis of LiFePO4/Graphene Nano composite and Its Electrochemical Properties as Cathode Material for Li-Ion Batteries

    International Nuclear Information System (INIS)

    Ma, X.; Chen, G.; Liu, Q.; Zeng, G.; Wu, T.

    2014-01-01

    LiFePO 4 /graphene nano composite was successfully synthesized by rheological phase method and its electrochemical properties as the cathode materials for lithium ion batteries were measured. As the iron source in the synthesis, FeOOH nano rods anchored on graphene were first synthesized. The FeOOH nano rods precursors and the final LiFePO 4 /graphene nano composite products were characterized by XRD, SEM, and TEM. While the FeOOH precursors were nano rods with 5-10 nm in diameter and 10-50 nm in length, the LiFePO 4 were nanoparticles with 20-100 nm in size. Compared with the electrochemical properties of LiFePO 4 particles without graphene nano sheets, it is clear that the graphene nano sheets can improve the performances of LiFePO 4 as the cathode material for lithium ion batteries. The as-synthesized LiFePO 4 /graphene nano composite showed high capacities and good cyclabilities. When measured at room temperature and at the rate of 0.1 C (1 C = 170 mA g -1 ), the composite showed a discharge capacity of 156 mA h g -1 in the first cycle and a capacity retention of 96% after 15 cycles. The improved performances of the composite are believed to be the result of the three-dimensional conducting network formed by the flexible and planar graphene nano sheets.

  15. High photocatalytic degradation activity of the polyvinyl chloride (PVC)-vitamin C (VC)-TiO2 nano-composite film

    International Nuclear Information System (INIS)

    Yang Changjun; Gong Chuqing; Peng Tianyou; Deng Kejian; Zan Ling

    2010-01-01

    A novel photodegradable polyvinyl chloride (PVC)-vitamin C (VC)-TiO 2 nano-composite film was prepared by embedding VC modified nano-TiO 2 photocatalyst into the commercial PVC plastic. The solid-phase photocatalytic degradation behavior of PVC-VC-TiO 2 nano-composite film under UV light irradiation was investigated and compared with those of the PVC-TiO 2 film and the pure PVC film, with the aid of UV-Vis spectroscopy, scanning electron microscopy (SEM), weight loss monitoring, and X-ray diffraction spectra (XRD). The results show that PVC-VC-TiO 2 nano-composite film has a high photocatalytic activity; the photocatalytic degradation rate of it is two times higher than that of PVC-TiO 2 film and fifteen times higher than that of pure PVC film. The optimal mass ratio of VC to TiO 2 is found to be 0.5. The mechanism of enhancing photocatalytic activity is attributed to the formation of a Ti IV -VC charge-transfer complex with five-member chelate ring structure and a rapid photogenerated charge separation is thus achieved.

  16. Fabrication of CDs/CdS-TiO2 ternary nano-composites for photocatalytic degradation of benzene and toluene under visible light irradiation

    Science.gov (United States)

    Wang, Meng; Hua, Jianhao; Yang, Yaling

    2018-06-01

    An efficient cadmium sulfide quantum-dots (CdS QDs) and carbon dots (CDs) modified TiO2 photocatalyst (CdS/CDs-TiO2) was successfully fabricated. The as-prepared ternary nano-composites simultaneously improved the photo-corrosion of CdS and amplified its photocatalytic activity. The introduction of CdS QDs and CDs could enhance more absorbance of light, prevent the undesirable electron/hole recombination, and promote charge separation, which was important for the continuous formation of rad OH and rad O2- radicals. When the optimal mass ratio of CdS QDs to CDs was 3:1, above 90% degradation efficiencies were achieved for benzene within 1 h and toluene in 2 h, while that of pure TiO2 (P25), CdS QDs-TiO2, CDs-TiO2 nano-composites was around 15%. Owing to the symmetric structure and conjugation of methyl with benzene ring, the degradation of toluene was more difficult than benzene to carry on. The new fabricated nano-composites showed good prospective application of cleaning up refractory pollutants and the resource utilization.

  17. Bio-Based Nano Composites from Plant Oil and Nano Clay

    Science.gov (United States)

    Lu, Jue; Hong, Chang K.; Wool, Richard P.

    2003-03-01

    We explored the combination of nanoclay with new chemically functionalized, amphiphilic, plant oil resins to form bio-based nanocomposites with improved physical and mechanical properties. These can be used in many new applications, including the development of self-healing nanocomposites through controlled reversible exfoliation/intercalation, and self-assembled nano-structures. Several chemically modified triglyceride monomers of varying polarity, combined with styrene (ca 30include acrylated epoxidized soybean oil (AESO), maleated acrylated epoxidized soybean oil (MAESO) and soybean oil pentaerythritol glyceride maleates (SOPERMA), containing either hydroxyl group or acid functionality or both. The clay used is a natural montmorillonite modified with methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride, which has hydroxyl groups. Both XRD and TEM showed a completely exfoliated structure at 3 wtwhen the clay content is above 5 wtconsidered a mix of intercalated and partially exfoliated structure. The controlled polarity of the monomer has a major effect on the reversible dispersion of clay in the polymer matrix. The bio-based nanocomposites showed a significant increase in flexural modulus and strength. Supported by EPA and DoE

  18. Novel calcified gum Arabic porous nano-composite scaffold for bone tissue regeneration.

    Science.gov (United States)

    Hadavi, M; Hasannia, S; Faghihi, Sh; Mashayekhi, F; Zadeh, H H; Mostofi, S B

    2017-07-08

    The aim of this study was to investigate the biomechanical and biological properties of a nanocomposite scaffold containing both mineral and polysaccharide constituents. Hydroxyapatite nanoparticles (n-HA) was synthesized from dead abra ovata shells using wet chemical methods and was used in different ratios in concert with gum Arabic, a branched plant polysaccharide. N-HA/gum nanocomposite was fabricated with freeze-drying process and characterized by FTIR and SEM for chemical structure and morphology. Porosity was estimated using liquid substitution method. The scaffold mechanical properties were evaluated by compressive test measurement. Osteogenic differentiation was assessed using alkaline phosphatase production and biomineralization was evaluated using Alizarin red assay. Results demonstrated that the hydroxyapatite/gum Arabic nanocomposite had favorable biocompatibility and a similar structure to natural bone matrix. Porous nanocomposite possessed macropore networks with a porosity 87-93% and mean pore size ranging between 164 and 230 μm. The gum/HA with a ratio of 50% w/w HA had the highest compressive modulus of ∼75.3 MPa Pa (MPa) and the ultimate compressive stress of ∼16.6 MPa. C2C12 cells cultured on a scaffold with higher percentage (40 and 50 w/w) of HA demonstrated increased ALP levels and calcium deposition. The data from the present study demonstrated significant changes to the biomechanical properties and osteoconductivity of the nanocomposite scaffold by modulating its mineral content. Nanocomposite scaffolds containing gum and n-HA of 40-50% exhibited highest mechanical properties, as well as supported increased biomineralization. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Dielectric relaxation and ac conduction in γ-irradiated UHMWPE/MWCNTs nano composites: Impedance spectroscopy analysis

    International Nuclear Information System (INIS)

    Maqbool, Syed Asad; Mehmood, Malik Sajjad; Mukhtar, Saqlain Saqib; Baluch, Mansoor A.; Khan, Shamim; Yasin, Tariq; Khan, Yaqoob

    2017-01-01

    The dielectric behavior of γ-irradiated ultra-high molecular weight polyethylene (UHMWPE) and its nano composites (NCs) with γ-ray modified multi wall carbon nano tubes (γ-MWCNTs) and MWCNTs had been studied using impedance spectroscopy. The study had been carried out in the frequency range of 20–2 MHz at room temperature. All samples (pure and NCs) were prepared in the form of sheets and irradiated with γ-dose of 50 kGy and 100 kGy, respectively. The comprehensive analysis of results revealed that resistivity of UHMWPE for conduction decreased on irradiation and incorporation of MWCNTs (whether γ ray modified or un-modified) due to the radiation induced damage and conductive networks induced by MWCNTs. At low frequency range a significant increase in the dielectric constant had been observed because of irradiation and addition of MWNCTs. The trend of loss tangent and ac conductivity for each investigated sample depended on resistivity offered and had a decreasing trend as a function of frequency. Moreover, dissipation factor increased with the incorporation of MWNCTs and irradiation from 0.12 to 0.22. In addition to this, non-frequency dependent static dielectric constant was also found to increase with irradiation and incorporation of MWCNTs. The relaxation time was found to increase from 1.2 to 4.3 ms due to hindrance offered by radiation induced mutual cross linking of PE chains and polymer-MWNCTs bindings. - Highlights: • The resistivity for conduction in pristine UHMWPE is decreased with γ-irradiation. • Conduction in PE/MWCNTs nanocomposites increased due to MWCNTs addition. • Static dielectric constant of UHMWPE increased with γ-irradiation. • Static dielectric constant of UHMWPE increased due to MWCNTs incorporation.

  20. An in vivo evaluation of PLLA/PLLA-gHA nano-composite for internal fixation of mandibular bone fractures.

    Science.gov (United States)

    Peng, Weihai; Zheng, Wei; Shi, Kai; Wang, Wangshu; Shao, Ying; Zhang, Duo

    2015-11-09

    Internal fixation of bone fractures using biodegradable poly(L-lactic-acid) (PLLA)-based materials has attracted the attention of many researchers. In the present study, 36 male beagle dogs were randomly assigned to two groups: PLLA/PLLA-gHA (PLLA-grafted hydroxyapatite) group and PLLA group. PLLA/PLLA-gHA and PLLA plates were embedded in the muscular bags of the erector spinae and also implanted to fix mandibular bone fractures in respective groups. At 1, 2, 3, 6, 9, and 12 months postoperatively, the PLLA/PLLA-gHA and PLLA plates were evaluated by adsorption and degradation tests, and the mandibles were examined through radiographic analysis, biomechanical testing, and histological analysis. The PLLA/PLLA-gHA plates were non-transparent and showed a creamy white color, and the PLLA plates were transparent and faint yellow in color. At all time points following surgery, adsorption and degradation of the PLLA/PLLA-gHA plates were significantly less than those of the PLLA plates, and the lateral and longitudinal bending strengths of the surgically treated mandibles of the beagle dogs in the PLLA/PLLA-gHA group were significantly greater than those of the PLLA group and reached almost the value of intact mandibles at 12 months postoperatively. Additionally, relatively rapid bone healing was observed in the PLLA/PLLA-gHA group with the formation of new lamellar bone tissues at 12 months after the surgery. The PLLA/PLLA-gHA nano-composite can be employed as a biodegradable material for internal fixation of mandibular bone fractures.

  1. An in vivo evaluation of PLLA/PLLA-gHA nano-composite for internal fixation of mandibular bone fractures

    International Nuclear Information System (INIS)

    Peng, Weihai; Shi, Kai; Wang, Wangshu; Shao, Ying; Zhang, Duo; Zheng, Wei

    2015-01-01

    Internal fixation of bone fractures using biodegradable poly(L-lactic-acid) (PLLA)-based materials has attracted the attention of many researchers. In the present study, 36 male beagle dogs were randomly assigned to two groups: PLLA/PLLA-gHA (PLLA-grafted hydroxyapatite) group and PLLA group. PLLA/PLLA-gHA and PLLA plates were embedded in the muscular bags of the erector spinae and also implanted to fix mandibular bone fractures in respective groups. At 1, 2, 3, 6, 9, and 12 months postoperatively, the PLLA/PLLA-gHA and PLLA plates were evaluated by adsorption and degradation tests, and the mandibles were examined through radiographic analysis, biomechanical testing, and histological analysis. The PLLA/PLLA-gHA plates were non-transparent and showed a creamy white color, and the PLLA plates were transparent and faint yellow in color. At all time points following surgery, adsorption and degradation of the PLLA/PLLA-gHA plates were significantly less than those of the PLLA plates, and the lateral and longitudinal bending strengths of the surgically treated mandibles of the beagle dogs in the PLLA/PLLA-gHA group were significantly greater than those of the PLLA group and reached almost the value of intact mandibles at 12 months postoperatively. Additionally, relatively rapid bone healing was observed in the PLLA/PLLA-gHA group with the formation of new lamellar bone tissues at 12 months after the surgery. The PLLA/PLLA-gHA nano-composite can be employed as a biodegradable material for internal fixation of mandibular bone fractures. (paper)

  2. Creatinine and urea biosensors based on a novel ammonium ion-selective copper-polyaniline nano-composite.

    Science.gov (United States)

    Zhybak, M; Beni, V; Vagin, M Y; Dempsey, E; Turner, A P F; Korpan, Y

    2016-03-15

    The use of a novel ammonium ion-specific copper-polyaniline nano-composite as transducer for hydrolase-based biosensors is proposed. In this work, a combination of creatinine deaminase and urease has been chosen as a model system to demonstrate the construction of urea and creatinine biosensors to illustrate the principle. Immobilisation of enzymes was shown to be a crucial step in the development of the biosensors; the use of glycerol and lactitol as stabilisers resulted in a significant improvement, especially in the case of the creatinine, of the operational stability of the biosensors (from few hours to at least 3 days). The developed biosensors exhibited high selectivity towards creatinine and urea. The sensitivity was found to be 85 ± 3.4 mAM(-1)cm(-2) for the creatinine biosensor and 112 ± 3.36 mAM(-1)cm(-2) for the urea biosensor, with apparent Michaelis-Menten constants (KM,app), obtained from the creatinine and urea calibration curves, of 0.163 mM for creatinine deaminase and 0.139 mM for urease, respectively. The biosensors responded linearly over the concentration range 1-125 µM, with a limit of detection of 0.5 µM and a response time of 15s. The performance of the biosensors in a real sample matrix, serum, was evaluated and a good correlation with standard spectrophotometric clinical laboratory techniques was found. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. FeOOH-loaded MnO2 nano-composite: An efficient emergency material for thallium pollution incident.

    Science.gov (United States)

    Chen, Meiqing; Wu, Pingxiao; Yu, Langfeng; Liu, Shuai; Ruan, Bo; Hu, Haihui; Zhu, Nengwu; Lin, Zhang

    2017-05-01

    A FeOOH-loaded MnO 2 nano-composite was developed as an emergency material for Tl(I) pollution incident. Structural characterizations showed that FeOOH successfully loaded onto MnO 2 , the nanosheet-flower structure and high surface area (191 m 2  g -1 ) of material contributed to the excellent performance for Tl(I) removal. FeOOH-loaded MnO 2 with a Fe/Mn molar ratio of 1:2 exhibited a noticeable enhanced capacity for Tl(I) removal compared to that of pure MnO 2 . The outstanding performance for Tl(I) removal involves in extremely high efficiency (achieved equilibrium and drinking water standard within 4 min) and the large maximum adsorption capacity (450 mg g -1 ). Both the control-experiment and XPS characterization proved that the removal mechanism of Tl(I) on FeOOH-loaded MnO 2 included adsorption and oxidation: the oxidation of MnO 2 played an important role for Tl(I) removal, and the adsorption of FeOOH loaded on MnO 2 enhanced Tl(I) purification at the same time. In-depth purification of Tl(I) had reach drinking water standards (0.1 μg L -1 ) at pH above 7, and there wasn't security risk produced from the dissolution of Mn 2+ and Fe 2+ . Moreover, the as-prepared material could be utilized as a recyclable adsorbent regenerated by using NaOH-NaClO binary solution. Therefore, the synthesized FeOOH-loaded MnO 2 in this study has the potential to be applied as an emergency material for thallium pollution incident. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Atoms in dense plasmas

    International Nuclear Information System (INIS)

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs

  5. Atoms in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  6. Characterizing reactive oxygen generation and bacterial inactivation by a zerovalent iron-fullerene nano-composite device at neutral pH under UV-A illumination

    International Nuclear Information System (INIS)

    Erdim, Esra; Badireddy, Appala Raju; Wiesner, Mark R.

    2015-01-01

    Highlights: • We synthesized a novel ZVI/nC 60 nano-composite device for multi-ROS generation. • O 2 · − (UV-A independent) and 1 O 2 (UV-A dependent) are generated at neutral pH. • At low Fe concentration, ZVI/nC 60 device is a better ROS generator than ZVI alone. • C 60 mediates electron transfer from ZVI surface to dissolved O 2 to produce O 2 · − . • Bacteria are rapidly inactivated by O 2 · − even at low ZVI/nC 60 ratio. - Abstract: A nano-composite device composed of nano-scale zerovalent iron (ZVI) and C 60 fullerene aggregates (ZVI/nC 60 ) was produced via a rapid nucleation method. The device was conceived to deliver reactive oxygen species (ROS) generated by photosensitization and/or electron transfer to targeted contaminants, including waterborne pathogens under neutral pH conditions. Certain variations of the nano-composite were fabricated differing in the amounts of (1) ZVI (0.1 mM and 2 mM) but not nC 60 (2.5 mg-C/L), and (2) nC 60 (0–25 mg-C/L) but not ZVI (0.1 mM). The generation of ROS by the ZVI/nC 60 nano-composites and ZVI nanoparticles was quantified using organic probe compounds. 0.1 mM ZVI/2.5 mg-C/L C 60 generated 3.74-fold higher O 2 · − concentration and also resulted in an additional 2-log inactivation of Pseudomonas aeruginosa when compared to 0.1 mM ZVI (3-log inactivation). 2 mM ZVI/2.5 mg-C/L nC 60 showed negligible improvement over 2 mM ZVI in terms of O 2 · − generation or inactivation. Further, incremental amounts of nC 60 in the range of 0–25 mg-C/L in 0.1 mM ZVI/nC 60 led to increased O 2 · − concentration, independent of UV-A. This study demonstrates that ZVI/nC 60 device delivers (1) enhanced O 2 · − with nC 60 as a mediator for electron transfer, and (2) 1 O 2 (only under UV-A illumination) at neutral pH conditions

  7. Contents

    Directory of Open Access Journals (Sweden)

    Editor IJRED

    2012-11-01

    Full Text Available International Journal of Renewable Energy Development www.ijred.com Volume 1             Number 3            October 2012                ISSN 2252- 4940   CONTENTS OF ARTICLES page Design and Economic Analysis of a Photovoltaic System: A Case Study 65-73 C.O.C. Oko , E.O. Diemuodeke, N.F. Omunakwe, and E. Nnamdi     Development of Formaldehyde Adsorption using Modified Activated Carbon – A Review 75-80 W.D.P Rengga , M. Sudibandriyo and M. Nasikin     Process Optimization for Ethyl Ester Production in Fixed Bed Reactor Using Calcium Oxide Impregnated Palm Shell Activated Carbon (CaO/PSAC 81-86 A. Buasri , B. Ksapabutr, M. Panapoy and N. Chaiyut     Wind Resource Assessment in Abadan Airport in Iran 87-97 Mojtaba Nedaei       The Energy Processing by Power Electronics and its Impact on Power Quality 99-105 J. E. Rocha and B. W. D. C. Sanchez       First Aspect of Conventional Power System Assessment for High Wind Power Plants Penetration 107-113 A. Merzic , M. Music, and M. Rascic   Experimental Study on the Production of Karanja Oil Methyl Ester and Its Effect on Diesel Engine 115-122 N. Shrivastava,  , S.N. Varma and M. Pandey  

  8. The taxation of unhealthy energy-dense foods (EDFs) and sugar-sweetened beverages (SSBs): An overview of patterns observed in the policy content and policy context of 13 case studies.

    Science.gov (United States)

    Hagenaars, Luc Louis; Jeurissen, Patrick Paulus Theodoor; Klazinga, Niek Sieds

    2017-08-01

    Taxation of energy-dense foods (EDFs) and sugar-sweetened beverages (SSBs) is increasingly of interest as a novel public health and fiscal policy instrument. However academic interest in policy determinants has remained limited. We address this paucity by comparing the policy content and policy context of EDF/SSB taxes witnessed in 13 case studies, of which we assume the tax is sufficiently high to induce behavioural change. The observational and non-randomized studies published on our case studies seem to indicate that the EDF/SSB taxes under investigation generally had the desired effects on prices and consumption of targeted products. The revenue collection of EDF/SSB taxes is minimal yet significant. Administrative practicalities in tax levying are important, possibly explaining why a drift towards solely taxing SSBs can be noted, as these can be demarcated more easily, with levies seemingly increasing in more recent case studies. Despite the growing body of evidence suggesting that EDF/SSB taxes have the potential to improve health, fiscal needs more often seem to lay their policy foundation rather than public health advocacy. A remarkable amount of conservative/liberal governments have adopted these taxes, although in many cases revenues are earmarked for benefits compensating regressive income effects. Governments voice diverse policy rationales, ranging from explicitly describing the tax as a public health instrument, to solely explicating revenue raising. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. A comparative study of gelatin and starch-based nano-composite films modified by nano-cellulose and chitosan for food packaging applications.

    Science.gov (United States)

    Noorbakhsh-Soltani, S M; Zerafat, M M; Sabbaghi, S

    2018-06-01

    Environmental concerns have led to extensive research for replacing polymer-based food packaging with bio-nano-composites. In this study, incorporation of nano-cellulose into gelatin and starch matrices is investigated for this purpose. Chitosan is used to improve mechanical, anti-fungal and waterproof properties. Experiments are designed and analyzed using response surface methodology. Nano-Cellulose is synthesized via acid hydrolysis and incorporated in base matrices through wet processing. Also, tensile strength test, food preservation, transparency in visible and UV and water contact angle are performed on the nano-composite films. DSC/TGA and air permeability tests are also performed on the optimal films. The results show that increasing nano-cellulose composition to 10% leads to increase the tensile strength at break to 8121 MN/m 2 and decrease the elongation at break. Also, increasing chitosan composition from 5% to 30% can enhance food preservation up to 15 days. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Effect of high energy electron beam (10 MeV) on specific heat capacity of low-density polyethylene/hydroxyapatite nano-composite

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, Z., E-mail: zhr_soltani@yahoo.com [Health Physics and Radiation Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ziaie, F. [Radiation Application Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of); Ghaffari, M. [Polymer Group, Golestan University, Golestan (Iran, Islamic Republic of); Beigzadeh, A.M. [Radiation Application Research School, Nuclear Science & Technology Research Institute, Tehran (Iran, Islamic Republic of)

    2017-02-01

    In the present work, thermal properties of low density polyethylene (LDPE) and its nano composites are investigated. For this purpose LDPE reinforced with different weight percents of hydroxyapatite (HAP) powder which was synthesized via hydrolysis method are produced. The samples were irradiated with 10 MeV electron beam at doses of 75 to 250 kGy. Specific heat capacity measurement have been carried out at different temperatures, i.e. 25, 50, 75 and 100 °C using modulated temperature differential scanning calorimetry (MTDSC) apparatus and the effect of three parameters include of temperature, irradiation dose and the amount of HAP nano particles as additives on the specific heat capacity of PE/HAP have been investigated precisely. The MTDSC results indicate that the specific heat capacity have decreased by addition of nano sized HAP as reinforcement for LDPE. On the other hand, the effect of radiation dose is reduction in the specific heat capacity in all materials including LDPE and its nano composites. The HAP nano particles along with cross-link junctions due to radiation restrain the movement of the polymer chains in the vicinity of each particle and improve the immobility of polymer chains and consequently lead to reduction in specific heat capacity. Also, the obtained results confirm that the radiation effect on the specific heat capacity is more efficient than the reinforcing effect of nano-sized hydroxyapatite.

  11. Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

    International Nuclear Information System (INIS)

    Hsiang, Hsing-I.; Chang, Yu-Lun; Chen, Chi-Yu; Yen, Fu-Su

    2011-01-01

    Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO 2 /ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO 2 particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO 2 nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio of 0.6. This produced a decrease in abrasion resistance.

  12. Quantum dense key distribution

    International Nuclear Information System (INIS)

    Degiovanni, I.P.; Ruo Berchera, I.; Castelletto, S.; Rastello, M.L.; Bovino, F.A.; Colla, A.M.; Castagnoli, G.

    2004-01-01

    This paper proposes a protocol for quantum dense key distribution. This protocol embeds the benefits of a quantum dense coding and a quantum key distribution and is able to generate shared secret keys four times more efficiently than the Bennet-Brassard 1984 protocol. We hereinafter prove the security of this scheme against individual eavesdropping attacks, and we present preliminary experimental results, showing its feasibility

  13. Effect of high content nano-thoria addition on the properties of tungsten electrode

    International Nuclear Information System (INIS)

    Wang Fazhan; Zhuge Fei; Zhang Hui; Ding Bingjun

    2003-01-01

    By hot swaging, the nano-composite W-4.5%ThO 2 cathode was fabricated. A comparative investigation has been made on the operation characteristics for a conventional W-2%ThO 2 cathode, a conventional W-4%ThO 2 cathode and a nano-composite W-4.5%ThO 2 cathode. The results showed that the arc starting and arc voltage-current characteristic of the nano-composite W-4.5%ThO 2 electrode was the best among the three cathodes. These operating characteristics depended on the content and the size of thoria. The anti-erosion ability of the nano-composite W-4.5%ThO 2 cathode was slightly better than that of conventional W-4%ThO 2 cathode, but was obviously improved as compared to W-2%ThO 2 cathode, indicating that the content of thoria governs the resistance to arc erosion of the electrodes

  14. Preparation of EVA/silica nano composites characterized with solid state nuclear magnetic resonance; Obtencao de nanocomposito de EVA/SILICA e caracterizacao por ressonancia magnetica nuclear no estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Passos, Adriano A; Tavares, Maria I.B.; Neto, Roberto C.P.; Moreira, Leonardo A; Ferreira, Antonio G., E-mail: mibt@ima.ufrj.br [Centro de Tecnologia, Instituto de Macromoleculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Nano composites of poly(ethylene-co-vinyl acetate)/silica (SiO{sub 2}) with dimensions of ca. 40 nm were prepared via solution intercalation employing chloroform as a solvent. They were mainly characterized with nuclear magnetic resonance spectroscopy (NMR) employing carbon-13 (polymeric matrix), silicon-29 (nanoparticles) and through the determination of the proton spin-lattice relaxation time in the rotating frame (T{sub 1{rho}H}) (polymer matrix). From the NMR results it was inferred that up to 5% of silica in mass a well dispersed nano composite was obtained, owing to a strong interaction between silica and the EVA matrix. (author)

  15. 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.

  16. Microstructure, mechanical response and fractography of AZ91E/Al2O3 (p nano composite fabricated by semi solid stir casting method

    Directory of Open Access Journals (Sweden)

    Sameer Kumar D.

    2017-03-01

    Full Text Available The present study confers to the fabrication and its characterization of magnesium alloy (AZ91E based nano composites with nano Al2O3 particulate reinforcements. A novel Semi Solid stir casting technique was adopted for the fabrication of the composite. An average particle size of 50 nm was used as reinforcement to disperse in matrix. The effects of change in weight fraction of reinforcements on the distribution of particles, particle–matrix interfacial reactions, physical as well as mechanical properties were reported. The SEM and EDS analysis has shown the uniform distribution of particles in the composite along with the presence of elements. The mechanical properties of reinforced and unreinforced composite were evaluated and presented. Fractography of tensile specimens was also discussed.

  17. Microstructures and mechanical properties of Al/Al2O3 surface nano-composite layer produced by friction stir processing

    International Nuclear Information System (INIS)

    Shafiei-Zarghani, A.; Kashani-Bozorg, S.F.; Zarei-Hanzaki, A.

    2009-01-01

    In this study, a new processing technique, friction stir processing (FSP) was attempted to incorporate nano-sized Al 2 O 3 into 6082 aluminum alloy to form particulate composite surface layer. Samples were subjected to various numbers of FSP passes from one to four, with and without Al 2 O 3 powder. Microstructural observations were carried out by employing optical and scanning electron microscopy (SEM) of the cross sections both parallel and perpendicular to the tool traverse direction. Mechanical properties include microhardness and wear resistance, were evaluated in detail. The results show that the increasing in number of FSP passes causes a more uniform in distribution of nano-sized alumina particles. The microhardness of the surface improves by three times as compared to that of the as-received Al alloy. A significant improvement in wear resistance in the nano-composite surfaced Al is observed as compared to the as-received Al

  18. Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells

    Science.gov (United States)

    Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C. H.

    2016-03-01

    The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self

  19. Characterizing reactive oxygen generation and bacterial inactivation by a zerovalent iron-fullerene nano-composite device at neutral pH under UV-A illumination

    Energy Technology Data Exchange (ETDEWEB)

    Erdim, Esra [Center for the Environmental Implications of NanoTechnology, Duke University, Durham, NC 27708 (United States); Environmental Engineering Department, Marmara University, Istanbul 34469 (Turkey); Badireddy, Appala Raju [Center for the Environmental Implications of NanoTechnology, Duke University, Durham, NC 27708 (United States); Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708 (United States); Wiesner, Mark R., E-mail: wiesner@duke.edu [Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708 (United States); Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708 (United States)

    2015-02-11

    Highlights: • We synthesized a novel ZVI/nC{sub 60} nano-composite device for multi-ROS generation. • O{sub 2}·{sup −} (UV-A independent) and {sup 1}O{sub 2} (UV-A dependent) are generated at neutral pH. • At low Fe concentration, ZVI/nC{sub 60} device is a better ROS generator than ZVI alone. • C{sub 60} mediates electron transfer from ZVI surface to dissolved O{sub 2} to produce O{sub 2}·{sup −}. • Bacteria are rapidly inactivated by O{sub 2}·{sup −} even at low ZVI/nC{sub 60} ratio. - Abstract: A nano-composite device composed of nano-scale zerovalent iron (ZVI) and C{sub 60} fullerene aggregates (ZVI/nC{sub 60}) was produced via a rapid nucleation method. The device was conceived to deliver reactive oxygen species (ROS) generated by photosensitization and/or electron transfer to targeted contaminants, including waterborne pathogens under neutral pH conditions. Certain variations of the nano-composite were fabricated differing in the amounts of (1) ZVI (0.1 mM and 2 mM) but not nC{sub 60} (2.5 mg-C/L), and (2) nC{sub 60} (0–25 mg-C/L) but not ZVI (0.1 mM). The generation of ROS by the ZVI/nC{sub 60} nano-composites and ZVI nanoparticles was quantified using organic probe compounds. 0.1 mM ZVI/2.5 mg-C/L C{sub 60} generated 3.74-fold higher O{sub 2}·{sup −} concentration and also resulted in an additional 2-log inactivation of Pseudomonas aeruginosa when compared to 0.1 mM ZVI (3-log inactivation). 2 mM ZVI/2.5 mg-C/L nC{sub 60} showed negligible improvement over 2 mM ZVI in terms of O{sub 2}·{sup −} generation or inactivation. Further, incremental amounts of nC{sub 60} in the range of 0–25 mg-C/L in 0.1 mM ZVI/nC{sub 60} led to increased O{sub 2}·{sup −} concentration, independent of UV-A. This study demonstrates that ZVI/nC{sub 60} device delivers (1) enhanced O{sub 2}·{sup −} with nC{sub 60} as a mediator for electron transfer, and (2) {sup 1}O{sub 2} (only under UV-A illumination) at neutral pH conditions.

  20. Graphene/Gold Nano composites-Based Thin Films as an Enhanced Sensing Platform for Voltammetric Detection of Cr(VI) Ions

    International Nuclear Information System (INIS)

    Santhosh, Ch.; Saranya, M.; Ramachandran, R.; Felix, S.; Velmurugan, V.; Grace, A.N.

    2014-01-01

    A highly sensitive and selective Cr(VI) sensor with graphene-based nano composites film as an enhanced sensing platform is reported. The detection of chromium species is a challenging task because of the different possible oxidation states in which the element can occur. The sensing film was developed by homogeneously distributing Au nanoparticles (AuNPs) onto the two-dimensional (2D) graphene nano sheet matrix by electrochemical method. Such nano structured composite film platforms combine the advantages of AuNPs and graph ene nano sheets because of the synergistic effect between them. This effect greatly facilitates the electron-transfer processes and the sensing behavior for Cr(VI) detection, leading to a remarkably improved sensitivity and selectivity. The interference from other heavy metal ions is studied in detail. Such sensing elements are very promising for practical environmental monitoring applications.

  1. Investigations of Relaxation Dynamics and Observation of Nearly Constant Loss Phenomena in PEO_2_0-LiCF_3SO_3-ZrO_2 Based Polymer Nano-Composite Electrolyte

    International Nuclear Information System (INIS)

    Dam, Tapabrata; Tripathy, Satya N.; Paluch, Marian; Jena, Sidhartha S.; Pradhan, Dillip K.

    2016-01-01

    Highlights: • Ion conduction mechanism is studied using broad band dielectric spectroscopy. • Existence and cause of Nearly Constant Loss is explored. • The crossover between UDR to NCL phenomena is investigated. • Effect of filler concentration on ion transport using scaling approach is discussed. - Abstract: The conduction mechanism of polymer nano-composite electrolytes are studied using broadband dielectric spectroscopy over a wide range of frequency and temperature. The polymer nano-composites consisting of polyethylene oxide as polymer host, lithium trifluoromethanesulfonate as salt, and nano-crystalline zirconia as filler are prepared using solution casting method. Formation of polymer salt complex and nano-composites are confirmed from x-ray diffraction studies. The electrical conductivity and relaxation phenomena of the polymer salt complex as well as the composites are studied using broadband dielectric spectroscopy. At room temperature, the dc conductivity of the polymer nano-composites are found higher by two orders of magnitude than that of corresponding polymer salt complex. Temperature dependence of dc conductivity is following Vogel-Tamman-Fulcher trend, suggesting strong coupling between ionic conductivity and segmental relaxation in polymer electrolytes. Relaxation phenomena are studied with dielectric and modulus formalism. Frequency dependent ac conductivity show universal dielectric response and nearly constant loss features at high and low temperature regions respectively. The origin of universal dielectric response and nearly constant loss are analysed and discussed using different approaches. Kramer - Krönig approach suggests the origin of nearly constant loss is due to caged ion dynamics feature.

  2. Synthesis and properties of Ag/ZnO/g-C3N4 ternary micro/nano composites by microwave-assisted method

    Science.gov (United States)

    Zhang, Zijie; Li, Xuexue; Chen, Haitao; Shao, Gang; Zhang, Rui; Lu, Hongxia

    2018-01-01

    Ag/ZnO/g-C3N4 ternary micro/nanocomposites, as novel visible-light-driven photocatalysts, were prepared by a simple and convenient microwave-assisted method. The resulting ternary structure micro/nano composites were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy and infrared radiation techniques to examine its phase structure, valence state, morphological, thermal and optical properties. Well crystallized Ag/ZnO/g-C3N4 ternary micro/nano composites were synthesized under microwave-radiation for 15 min with the output of 240 W. Further experiments indicated Ag(5.0mol%)/ZnO/g-C3N4 photocatalyst in degradation of methylene blue exhibited an outstanding photocatalytic activity and its reaction rate constant (k, 0.0084 min-1) is 7.5, 2.4 2.9 and 3.5 times higher than that of monolithic ZnO (k, 0.0011 min-1), ZnO/g-C3N4(k, 0.0035 min-1), Ag(5 mol%)/ZnO(k, 0.0029 min-1) and Ag(5mol%)/g-C3N4 (k, 0.0024 min-1) respectively. Finally, a possible photocatalytic mechanism of Ag/ZnO/g-C3N4 photocatalyst in degradation process was proposed. This work provides a feasible strategy to synthesize an efficient ZnO-based photocatalyst which combines structure and properties of different dimensional components and made this ternary system an exciting candidate for sunlight-driven photocatalytic water treatment.

  3. Strengthening analyses and mechanical assessment of Ti/Al{sub 2}O{sub 3} nano-composites produced by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Shafiei-Zarghani, Aziz, E-mail: ashafiei@ut.ac.ir [Center of Excellence for Surface Engineering and Corrosion Protection of Industries, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Kashani-Bozorg, Seyed Farshid, E-mail: fkashani@ut.ac.ir [Center of Excellence for Surface Engineering and Corrosion Protection of Industries, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Gerlich, Adrian P., E-mail: adrian.gerlich@uwaterloo.ca [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (Canada)

    2015-04-17

    The present work investigates strengthening mechanisms and mechanical assessment of Ti/Al{sub 2}O{sub 3} nano-composites produced by friction stir processing of commercially pure titanium using nano-sized Al{sub 2}O{sub 3} with different volume fractions and particle sizes. Microstructural analyses were conducted to characterize the grain size of matrix, size and dispersion of reinforcing particles. The mean grain size of the composites ranged from ~0.7 to 1.1 μm that is much lower than 28 μm of the as-received material. Reduction of grain size was found to be in agreement with Rios approach (based on energy dissipated during the motion of an interface through particle dispersion), and showed deviation from Zener pinning model. Scanning and transmission electron microscopies revealed a near uniform dispersion of Al{sub 2}O{sub 3} nano-particles, with only a small fraction of widely spaced clusters. The maximum compression yield strength of the fabricated nano-composite (Ti/3.9%vol of 20 nm-Al{sub 2}O{sub 3}) was found to be ~494 MPa that is ~1.5 times higher than that of the as-received material. Strengthening analyses based on grain refining (Hall–Petch approach), load transfer from matrix to reinforcements, Orowan looping, and enhanced dislocation density due to thermal mismatch effects were carried out considering Al{sub 2}O{sub 3} reinforcement with different volume fractions and sizes. However, Hall–Petch approach was found to be the dominant mechanism for the enhancement of yield strength.

  4. Modelling dense relational data

    DEFF Research Database (Denmark)

    Herlau, Tue; Mørup, Morten; Schmidt, Mikkel Nørgaard

    2012-01-01

    they are not naturally suited for kernel K-means. We propose a generative Bayesian model for dense matrices which generalize kernel K-means to consider off-diagonal interactions in matrices of interactions, and demonstrate its ability to detect structure on both artificial data and two real data sets....

  5. Is dense codeswitching complex?

    NARCIS (Netherlands)

    Dorleijn, M.

    In this paper the question is raised to what extent dense code switching can be considered complex. Psycholinguistic experiments indicate that code switching involves cognitive costs, both in production and comprehension, a conclusion that could indicate that code switching is indeed complex. In

  6. Simulation of dense colloids

    NARCIS (Netherlands)

    Herrmann, H.J.; Harting, J.D.R.; Hecht, M.; Ben-Naim, E.

    2008-01-01

    We present in this proceeding recent large scale simulations of dense colloids. On one hand we simulate model clay consisting of nanometric aluminum oxide spheres in water using realistic DLVO potentials and a combination of MD and SRD. We find pronounced cluster formation and retrieve the shear

  7. Preparation of Ag@mSiO{sub 2} and Pt@mSiO{sub 2}nano composites using trioctylmethyl ammonium hydrogen phthalate (TOMAHP) ionic liquid as reaction medium

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Sujoy, E-mail: sujoyb@barc.gov.in [Chemical Engineering Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dasgupta, Kinshuk [Materials Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Bahadur, Jitendra [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tewari, Raghavendra [Materials Group, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mazumder, Subhasish [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-09-15

    A novel one step green chemistry approach utilizing trioctylmethyl ammonium hydrogen phthalate (TOMAHP), task specific ionic liquid has been attempted for synthesis of Ag and Pt nanoparticles supported on silica (Ag@mSiO{sub 2} and Pt@mSiO{sub 2}). Structure, size distribution and morphology of these nano-composite particles were evaluated using X-ray diffraction (XRD), transmission electron microscopy (TEM), small angle neutron scattering (SANS) as well as small angle X-ray scattering (SAXS) techniques. The XRD results show that Ag/Pt metal nanoparticles deposited on to SiO{sub 2} surface are face center cubic (fcc) in nature. The TEM and SAXS/SANS results show the morphology and size distributions of Ag and Pt nanoparticles loaded on to the surface of SiO{sub 2}. It has been found that Ag nanoparticles are well dispersed on to the SiO{sub 2} surface and are quite monodisperse in size, whereas Pt nanoparticles are quite polydisperse in size and forms aggregate or chain like structure on SiO{sub 2} surface containing primary nanoparticles of typical size range 3–7 nm. The stability of nanoparticles, which controls its dispersion on SiO{sub 2} substrate, has been discussed. - Graphical abstract: Mechanism for Ag@mSiO{sub 2} and Pt@mSiO{sub 2} nano composites in TOMAHP ionic liquid medium. - Highlights: • Novel methods for preparation of Pt@SiO{sub 2} and Ag@SiO{sub 2} nano composite in functionalized ionic liquid. • Pt@SiO{sub 2} and Ag@SiO{sub 2} nano composite are characterized using XRD, TEM as well as small angle x-ray scattering techniques. • The sizes of nano composite is <10 nm in size. • The method is simple one step, green chemical reduction method to prepare SiO{sub 2} support nano catalyst.

  8. Dry processing versus dense medium processing for preparing thermal coal

    CSIR Research Space (South Africa)

    De Korte, GJ

    2013-10-01

    Full Text Available of the final product. The separation efficiency of dry processes is, however, not nearly as good as that of dense medium and, as a result, it is difficult to effectively beneficiate coals with a high near-dense content. The product yield obtained from some raw...

  9. Atoms in dense plasmas

    International Nuclear Information System (INIS)

    More, R.M.

    1987-01-01

    This paper covers some aspects of the theory of atomic processes in dense plasmas. Because the topic is very broad, a few general rules which give useful guidance about the typical behavior of dense plasmas have been selected. These rules are illustrated by semiclassical estimates, scaling laws and appeals to more elaborate calculations. Included in the paper are several previously unpublished results including a new mechanism for electron-ion heat exchange (section II), and an approximate expression for oscillator-strengths of highly charged ions (section V). However the main emphasis is not upon practical formulas but rather on questions of fundamental theory, the structural ingredients which must be used in building a model for plasma events. What are the density effects and how does one represent them? Which are most important? How does one identify an incorrect theory? The general rules help to answer these questions. 106 references, 23 figures, 2 tables

  10. Dense Plasma Focus Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hui [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Li, Shengtai [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jungman, Gerard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hayes-Sterbenz, Anna Catherine [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-31

    The mechanisms for pinch formation in Dense Plasma Focus (DPF) devices, with the generation of high-energy ions beams and subsequent neutron production over a relatively short distance, are not fully understood. Here we report on high-fidelity 2D and 3D numerical magnetohydrodynamic (MHD) simulations using the LA-COMPASS code to study the pinch formation dynamics and its associated instabilities and neutron production.

  11. Barrier properties of PE, PP and EVA (nano)composites - The influence of filler type and concentration

    Energy Technology Data Exchange (ETDEWEB)

    Merinska, D.; Kalendova, A. [Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. T. G. Masaryka 275, 762 72 Zlin, Czech Republic and Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Nad Ovcirnou 3685, 760 0 (Czech Republic); Tesarikova, A. [Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Nam. T. G. Masaryka 275, 762 72 Zlin (Czech Republic)

    2014-05-15

    Nanocomposite materials with layered clay used as nanofiller and polyethylene (PE), polypropylene (PP) and copolymer ethylene and vinyl acetate matrix (EVA, the content of VA component 19 wt. %) were prepared by compounding the individual components in Brabender kneader. The MMT Na+ and four types of commercial products such as Nanofil N 5 and N3000, Cloisite 93A and 30B were used as nanofillers. Next to the clays microprecipitated CaHCO{sub 3}, nanosilica and Halloysite tubes were used. The quantity of all the above-mentioned (nano)fillers was 1, 3 and 5 wt. % in relation to the content of montmorillonite. The aim was to evaluate the influence of (nano)filler type and concentration on nanocomposite barrier properties. The morphology of nanocomposite samples was examined by means of XRD analysis illustrated by transmission electronic microscopy TEM. Furthermore, permeability for O{sub 2} and CO{sub 2} were observed.

  12. Dense ceramic articles

    International Nuclear Information System (INIS)

    Cockbain, A.G.

    1976-01-01

    A method is described for the manufacture of articles of substantially pure dense ceramic materials, for use in severe environments. Si N is very suitable for use in such environments, but suffers from the disadvantage that it is not amenable to sintering. Some disadvantages of the methods normally used for making articles of Si N are mentioned. The method described comprises mixing a powder of the substantially pure ceramic material with an additive that promotes densification, and which is capable of nuclear transmutation into a gas when exposed to radiation, and hot pressing the mixture to form a billet. The billet is then irradiated to convert the additive into a gas which is held captive in the billet, and it is then subjected to a hot forging operation, during which the captive gas escapes and an article of substantially pure dense ceramic material is forged. The method is intended primarily for use for Si N, but may be applied to other ceramic materials. The additive may be Li or Be or their compounds, to the extent of at least 5 ppm and not more than 5% by weight. Irradiation is effected by proton or neutron bombardment. (UK)

  13. DENSE MEDIUM CYCLONE OPTIMIZATON

    Energy Technology Data Exchange (ETDEWEB)

    Gerald H. Luttrell; Chris J. Barbee; Peter J. Bethell; Chris J. Wood

    2005-06-30

    Dense medium cyclones (DMCs) are known to be efficient, high-tonnage devices suitable for upgrading particles in the 50 to 0.5 mm size range. This versatile separator, which uses centrifugal forces to enhance the separation of fine particles that cannot be upgraded in static dense medium separators, can be found in most modern coal plants and in a variety of mineral plants treating iron ore, dolomite, diamonds, potash and lead-zinc ores. Due to the high tonnage, a small increase in DMC efficiency can have a large impact on plant profitability. Unfortunately, the knowledge base required to properly design and operate DMCs has been seriously eroded during the past several decades. In an attempt to correct this problem, a set of engineering tools have been developed to allow producers to improve the efficiency of their DMC circuits. These tools include (1) low-cost density tracers that can be used by plant operators to rapidly assess DMC performance, (2) mathematical process models that can be used to predict the influence of changes in operating and design variables on DMC performance, and (3) an expert advisor system that provides plant operators with a user-friendly interface for evaluating, optimizing and trouble-shooting DMC circuits. The field data required to develop these tools was collected by conducting detailed sampling and evaluation programs at several industrial plant sites. These data were used to demonstrate the technical, economic and environmental benefits that can be realized through the application of these engineering tools.

  14. Flow-induced crystallization of a nano composite of poly(butylene adipate-co-terephthalate)/montmorillonite; Cinetica de cristalizacao induzida por fluxo de nanocomposito de poli(butileno adipato-co-tereftalato)/montmorilonita

    Energy Technology Data Exchange (ETDEWEB)

    Bonel, Alan B [Universidade Federal de Sao Carlos. UFSCar, Departamento de Engenharia de Materiais DEMa, SP (Brazil); Rego, Bruna T; Beatrice, Cesar A.G.; Marini, Juliano; Bretas, Rosario E.S., E-mail: bretas@ufscar.br [Universidade Federal de Sao Carlos. UFSCar, Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, SP (Brazil)

    2011-07-01

    Poly(butylene adipate-co-terephthalate) (PBAT) with 5wt% of an organically modified montmorillonite with polar surfactant was prepared by melt blending in a co-rotational twin-screw extruder at 160 degree C. 100rpm and 1 kg/h. Both pure polymer and nano composite were characterized by wide measurements. The study of the flow-induced crystallization was also done by rheological measurements, monitoring the viscosity as a function of time. The nano clay's lamellas were intercalated in the polymer m loss moduli of the nano composite, at low frequencies, showed that the particles of the nano clay were well dispersed and distributed thru the PBAT matrix. Finally, the presence of the nano clay's particles reduced the induction tim crystals growth, due to the strong interactions with the PBAT chains. (author)

  15. Combinatorial study of low-refractive Mg-F-Si-O nano-composites deposited by magnetron co-sputtering from compound targets

    Science.gov (United States)

    Mertin, Stefan; Länzlinger, Tony; Sandu, Cosmin S.; Scartezzini, Jean-Louis; Muralt, Paul

    2018-03-01

    Deposition of nano-composite Mg-F-Si-O films on optical grade silica glass was studied employing RF magnetron co-sputtering from magnesium fluoride (MgF2) and fused silica (SiO2) targets. The aim was to obtain a stable and reliable sputtering process for optical coatings exhibiting a refractive index lower than the one of quartz glass (1.46 at 550 nm) without adding gaseous fluorine to the deposition process. The two magnetrons were installed in a confocal way at 45° off-axis with respect to a static substrate, thus creating a lateral gradient in the thin-film composition. The deposited Mg-F-Si-O coatings were structurally analysed by electron dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The obtained films consist of MgF2 nanocrystals embedded in a SiO2-rich amorphous matrix. Spectroscopic ellipsometry and spectrophotometry measurements showed that they are highly transparent exhibiting a very-low extinction coefficient k and a refractive index n in the desired range between the one of MgF2 (1.38) and SiO2 (1.46). Films with n = 1.424 and 1.435 at 550 nm were accomplished with absorption below the detection threshold.

  16. The antifungal effects and mechanical properties of silver bromide/cationic polymer nano-composite-modified Poly-methyl methacrylate-based dental resin.

    Science.gov (United States)

    Zhang, Yu; Chen, Yin-Yan; Huang, Li; Chai, Zhi-Guo; Shen, Li-Juan; Xiao, Yu-Hong

    2017-05-08

    Poly-methyl methacrylate (PMMA)-based dental resins with strong and long-lasting antifungal properties are critical for the prevention of denture stomatitis. This study evaluated the antifungal effects on Candida albicans ATCC90028, the cytotoxicity toward human dental pulp cells (HDPCs), and the mechanical properties of a silver bromide/cationic polymer nano-composite (AgBr/NPVP)-modified PMMA-based dental resin. AgBr/NPVP was added to the PMMA resin at 0.1, 0.2, and 0.3 wt%, and PMMA resin without AgBr/NPVP served as the control. Fungal growth was inhibited on the AgBr/NPVP-modified PMMA resin compared to the control (P  0.05) between the experimental and control groups. These data indicate that the incorporation of AgBr/NPVP conferred strong and long-lasting antifungal effects against Candida albicans to the PMMA resin, and it has low toxicity toward HDPCs, and its mechanical properties were not significantly affected.

  17. Improved dehydriding property of polyvinylpyrrolidone coated Mg-Ni hydrogen storage nano-composite prepared by hydriding combustion synthesis and wet mechanical milling

    Directory of Open Access Journals (Sweden)

    Linglong Yao

    2018-02-01

    Full Text Available In this work, polyvinylpyrrolidone (PVP coated Mg95Ni5 nano-composites were prepared by hydriding combustion synthesis (HCS plus wet mechanical milling (WM with tetrahydrofuran (THF and donated as WM-x wt% PVP (x = 1, 3, 5 and 7 respectively. The phase compositions, microstructures and dehydriding property, as well as the co-effect of PVP and THF were investigated in detail. XRD results showed that the average crystal size of MgH2 in the milled Mg95Ni5 decreased from 23 nm without PVP to 18 nm with 1 wt% PVP. The peak temperature of dehydrogenation of MgH2 in the milled Mg95Ni5 decreased from 293.0 °C without THF to 250.4 °C with THF. The apparent activation energy for decomposition of MgH2 in WM-7 wt% PVP was estimated to be 66.94 kJ/mol, which is 37.70 kJ/mol lower than that of milled Mg95Ni5 without THF and PVP. PVP and THF can facilitate the refinement of particle size during mechanical milling process. Attributed to small particle sizes and synergistic effect of PVP and THF, the composites exhibit markedly improved dehydriding properties. Keywords: Mg-Ni-PVP, Composite, Mg-based alloy, Wet mechanical milling, Dehydriding temperature

  18. In vitro secretion of TNF-{alpha} from bone marrow mononuclear cells incubated on amino group modified TiO{sub 2} nano-composite under ultrasound irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Furuzono, T., E-mail: furuzono@ri.ncvc.go.jp [Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565 (Japan); Masuda, M. [Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565 (Japan); Nitta, N.; Kaya, A.; Yamane, T. [Institute for Human Science and Biomedical Engineering, National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki, 305-8564 (Japan); Okada, M. [Department of Bioengineering, Advanced Medical Engineering Center, National Cardiovascular Center Research Institute, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565 (Japan)

    2010-10-15

    It is recently known that titanium dioxide (TiO{sub 2}) can be excited by ultrasound and release of OH radicals on the surface. In this study, secretion of an indirect angiogenic factor, tumor necrosis factor-{alpha} (TNF-{alpha}), from bone marrow mononuclear cells (BM-MNC) incubated on amino group modified TiO{sub 2} nano-particles covalently coated on polyester fabric (TiO{sub 2}/PET) under ultrasonic irradiation was examined in vitro. The cell viability and TNF-{alpha} secretion were measured under ultrasound irradiation condition with 255 mW/cm{sup 2} of intensity, which is below the highest output (1 W/cm{sup 2}) specified in the safety standard for a medical ultrasonic diagnostic apparatus. The living cell number on the TiO{sub 2}/PET and original PET with/without continuous ultrasound irradiation was unchanged statistically by ANOVA test. TNF-{alpha} secretion level from BM-MNC remarkably increased on the TiO{sub 2}/PET under ultrasonic irradiation without cell damage. It was, therefore, thought that the high level of TNF-{alpha} secretion on the TiO{sub 2} nano-composite by ultrasound irradiation was due to oxidative stress induced from OH radicals on TiO{sub 2}.

  19. Chitosan mediated synthesis of core/double shell ternary polyaniline/Chitosan/cobalt oxide nano composite-as high energy storage electrode material in supercapacitors

    International Nuclear Information System (INIS)

    Vellakkat, Mini; Hundekkal, Devendrappa

    2016-01-01

    Nanostructured ternary composite of polyaniline (PANI), Co 3 O 4 nanoparticles, and Chitosan (CS) has been prepared by an in situ chemical oxidation method, and the nanocomposites (CPAESCO) were used as supercapacitor electrodes. The Co 3 O 4 nanoparticles are uniformly coated with CS and PANI layers in it. Different techniques (Fourier transform infrared spectrophotometry, x-ray diffraction, thermal gravimetric analysis, UV−visible spectroscopy, scanning electron microscopy, transmission electron microscopy and electro chemical analysis-cyclic voltammetry, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy) were used to analyse the optical, structural, thermal, chemical and supercapacitive aspects of the nanocomposites. Core/double shell ternary composite electrode exhibits significantly increased specific capacitance than PANI/Co 3 O 4 or PANI/CS binary composites in supercapacitors. The ternary nanocomposite with 40% nanoparticle exhibits a highest specific capacitance reaching 687 F g −1 , Energy density of (95.42 Wh kg −1 at 1 A g −1 ) and power density of (1549 W kg −1 at 3 A g −1 ) and outstanding cycling performance, with, 91% capacitance retained over 5000 cycles. It is found that this unique bio compatible nano composite with synergy is a new multifunctional material which will be useful in the design of supercapacitor electrodes and other energy conversion devices too. (paper)

  20. Highly efficient inverted organic light emitting diodes by inserting a zinc oxide/polyethyleneimine (ZnO:PEI) nano-composite interfacial layer

    Science.gov (United States)

    Kaçar, Rifat; Pıravadılı Mucur, Selin; Yıldız, Fikret; Dabak, Salih; Tekin, Emine

    2017-06-01

    The electrode/organic interface is one of the key factors in attaining superior device performance in organic electronics, and inserting a tailor-made layer can dramatically modify its properties. The use of nano-composite (NC) materials leads to many advantages by combining materials with the objective of obtaining a desirable combination of properties. In this context, zinc oxide/polyethyleneimine (ZnO:PEI) NC film was incorporated as an interfacial layer into inverted bottom-emission organic light emitting diodes (IBOLEDs) and fully optimized. For orange-red emissive MEH-PPV based IBOLEDs, a high power efficiency of 6.1 lm W-1 at a luminance of 1000 cd m-2 has been achieved. Notably, the external quantum efficiency (EQE) increased from 0.1 to 4.8% and the current efficiency (CE) increased from 0.2 to 8.7 cd A-1 with rise in luminance (L) from 1000 to above 10 000 cd m-2 levels when compared to that of pristine ZnO-based devices. An identical device architecture containing a ZnO:PEI NC layer has also been used to successfully fabricate green and blue emissive IBOLEDs. The significant enhancement in the inverted device performance, in terms of luminance and efficiency, is attributed to a good energy-level alignment between the cathode/organic interface which leads to effective carrier balance, resulting in efficient radiative-recombination.

  1. Investigation of dosimetric characteristics of a core-shell quantum dots nano composite (CdTe/CdS/PMMA): fabrication of a new gamma sensor

    Science.gov (United States)

    Feizi, Shahzad; Zare, Hakimeh; Hoseinpour, Masoumeh

    2018-06-01

    CdTe/CdS-PMMA nanocomposite was prepared using dispersion of CdTe/CdS core-shell quantum dots (QDs) in poly methyl methacrylate (PMMA) polymer matrix. High-quality CdTe/CdS core/shell quantum dots were synthesized in aqueous solution and were transferred from water to chloroform using ligand-exchange process in the presence of 1-dodecanethiol (1-DDT). Transmission electron microscopy analysis reveals that the obtained nano-particles are highly crystalline nature with mean diameter of 3.6 nm. To prepare an ohmic contact detector, a conductive cell with two silver coated walls was designed and fabricated for exploring gamma detecting properties of the nano composite. New detector was assessed for the linearity of doserate response, angular dependence, sensitivity and repeatability. The results show that the dose rate response of the prepared sensor is linear in the dose rate range of 50-145 mGy/min. So this nanocomposite can be utilized as a potential gamma sensor in the medical radiation device design.

  2. Design and Fabrication of Al2O3-(W, TiC-TiN-Mo-Ni Nano-composite Cermet Tool Materials with Graded Structures

    Directory of Open Access Journals (Sweden)

    NI Xiu-ying

    2018-02-01

    Full Text Available Based on the analysis on temperature and stress distributions, as well as fatigue crack propagation in cutting tools, a model for designing compositional distribution and microstructure with graded characteristics was proposed. The addition of ductile phase and the introduction of the graded structure are beneficial to slow down the fatigue crack propagation rate and improve tool life.Al2O3-(W,TiC-TiN-Mo-Ni nano-composite tool material with graded structures was fabricated via two stage hot pressing sintering process, and the microstructure and mechanical properties were studied. The results show that the surface hardness, fracture toughness of inner layer and bending strength of the cermet with sintered gradient structure reach 19.258GPa, 10.015MPa·m1/2 and 1017.475MPa,respectively.The performance requirements to cutting tools were met. The dimple cleavage and torn edge of the binding phase in the fracture surfaces can be beneficial to the improvement of the fracture toughness and bending strength,so the resistance to fatigue crack propagation of tools is improved.

  3. Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

    Science.gov (United States)

    Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

    2017-10-01

    In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

  4. In vitro secretion of TNF-α from bone marrow mononuclear cells incubated on amino group modified TiO2 nano-composite under ultrasound irradiation

    International Nuclear Information System (INIS)

    Furuzono, T.; Masuda, M.; Nitta, N.; Kaya, A.; Yamane, T.; Okada, M.

    2010-01-01

    It is recently known that titanium dioxide (TiO 2 ) can be excited by ultrasound and release of OH radicals on the surface. In this study, secretion of an indirect angiogenic factor, tumor necrosis factor-α (TNF-α), from bone marrow mononuclear cells (BM-MNC) incubated on amino group modified TiO 2 nano-particles covalently coated on polyester fabric (TiO 2 /PET) under ultrasonic irradiation was examined in vitro. The cell viability and TNF-α secretion were measured under ultrasound irradiation condition with 255 mW/cm 2 of intensity, which is below the highest output (1 W/cm 2 ) specified in the safety standard for a medical ultrasonic diagnostic apparatus. The living cell number on the TiO 2 /PET and original PET with/without continuous ultrasound irradiation was unchanged statistically by ANOVA test. TNF-α secretion level from BM-MNC remarkably increased on the TiO 2 /PET under ultrasonic irradiation without cell damage. It was, therefore, thought that the high level of TNF-α secretion on the TiO 2 nano-composite by ultrasound irradiation was due to oxidative stress induced from OH radicals on TiO 2 .

  5. Fabrication of Al/Graphite/Al2O3 Surface Hybrid Nano Composite by Friction Stir Processing and Investigating The Wear and Microstructural Properties of The Composite

    Directory of Open Access Journals (Sweden)

    A. Mostafapour

    2012-10-01

    Full Text Available Friction stir processing was applied for fabricating an aluminum alloy based hybrid nano composite reinforced with nano sized Al2O3 and micro sized graphite particles. A mixture of Al2O3 and graphite particles was packed into a groove with 1 mm width and 4.5 mm depth, which had been cut in 5083 aluminum plate of 10 mm thick. Packed groove was subjected to friction stir processing in order to implement powder mixture into the aluminum alloy matrix. Microstructural properties were investigated by means of optical microscopy and scanning electron microscopy (SEM. It was found that reinforcement particle mixture was distributed uniformly in nugget zone. Wear resistance of composite was measured by dry sliding wear test. As a result, hybrid composite revealed significant reduction in wear rate in comparison with Al/AL2O3 composite produced by friction stir processing. Worn surface of the wear test samples were examined by SEM in order to determine wear mechanism.

  6. Sb/O nano-composites produced via Spark Discharge Generation for Li-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Simonin, L.; Lafont, U.; Tabrizi, N.; Schmidt-Ott, A.; Kelder, E.M. [TUDelft NanoStructured Matrials DelftChemTech, Julianalaan 136, 2628 BL Delft (Netherlands)

    2007-12-06

    Spark Discharge Generation (SDG) was used to produce powders of 10-20 nm of Sb and antimony oxides. Different composite materials with different textures were obtained either with an amorphous passive layer of antimony oxide or with crystalline cubic Sb{sub 2}O{sub 3}. The composition and shape of the different mixtures, depending on the production and collection conditions, were analysed via XRD and HRTEM coupled with EDX. The effect of the nature and the content of the oxides on the electrode performances were studied using Swagelok cells, cycled galvanostatically with a MACCOR cycler. (author)

  7. Characterization of dispersion of a nano composites PP/TiO{sub 2} non modified; Caracterizacao da dispersao dos nanocompositos de PP/TiO{sub 2} nao modificados

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Igor L.; Tavares, Maria I.B.; Silva, Vanessa A. da; Legramanti, Cintia, E-mail: igorl@ima.ufrj.br [Universidade Federal do Rio de Janeiro - UFRJ, Instituto de Macromoleculas - IMA (Brazil); Luetkmeyer, Leandro [Universidades Federais do Mato Grosso - UFMT, Escritorio de Inovacao Tecnologica - EIT (Brazil)

    2011-07-01

    Polymeric nano composites are composite materials where an inorganic particle, which has a dimension in the nanometer range, is dispersed in a polymer matrix. Nano composites, using polypropylene (PP) as matrix polymer and titanium dioxide (TiO{sub 2}) as filler, have great versatility in marketing applications, this factor is inherent in the PP and the inherent ability photo degraded TiO{sub 2} particles. This combination can lead to a widely used material and a degradation time after discharge reduced, there by becoming, a residue of low environmental impact. This study aimed to evaluate the dispersion and particle distribution of TiO{sub 2}, non modified, in PP matrix, using the process of preparation by melt extrusion pathway and characterization of the materials obtained: on the molecular dynamics, using low field NMR solid state, measures the relaxation time spin-network (T{sub 1}H); morphology using XRD technique, and thermal analysis technique with the TGA of pure PP and nano composites PP/TiO{sub 2}. (author)

  8. Hyperons in dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Dapo, Haris

    2009-01-28

    The hyperon-nucleon YN low momentum effective interaction (V{sub low} {sub k}) allows for an extensive study of the behavior of hyperons in dense matter, together with an investigation of effects of the presence of hyperons on dense matter. The first step towards this goal is the construction of the matrix elements for the hyperon-nucleon low momentum potential. In order to assess the different properties of hyperons within these potentials we calculate the hyperon single-particle potentials in the Hartree-Fock approximation for all of the interactions. Their dependence on both momentum and density, is studied. The single-particle potentials are then used to determine the chemical potential of hyperons in neutron stars. For nucleonic properties, the nucleon-nucleon V{sub low} {sub k} can be used with the caveat that the calculation of the ground-state energy of symmetric nuclear matter does not correctly reproduce the properties of matter at saturation. With the nucleon-nucleon V{sub low} {sub k} one is unable to reach the densities needed for the calculation of neutron star masses. To circumvent this problem we use two approaches: in the first one, we parametrize the entire nucleonic sector. In the second one, we replace only the three-body force. The former will enable us to study neutron star masses, and the latter for studying the medium's response to the external probe. In this thesis we take the external probe to be the neutrino. By combining this parametrization with the YN V{sub low} {sub k} potential, we calculate the equation of state of equilibrated matter. Performing the calculation in the Hartree-Fock approximation at zero temperature, the concentrations of all particles are calculated. From these we can ascertain at which densities hyperons appear for a wide range of parameters. Finally, we calculate the masses of neutron stars with these concentrations. For the calculation of the medium's response to an external probe, we replace the three

  9. Hyperons in dense matter

    International Nuclear Information System (INIS)

    Dapo, Haris

    2009-01-01

    The hyperon-nucleon YN low momentum effective interaction (V low k ) allows for an extensive study of the behavior of hyperons in dense matter, together with an investigation of effects of the presence of hyperons on dense matter. The first step towards this goal is the construction of the matrix elements for the hyperon-nucleon low momentum potential. In order to assess the different properties of hyperons within these potentials we calculate the hyperon single-particle potentials in the Hartree-Fock approximation for all of the interactions. Their dependence on both momentum and density, is studied. The single-particle potentials are then used to determine the chemical potential of hyperons in neutron stars. For nucleonic properties, the nucleon-nucleon V low k can be used with the caveat that the calculation of the ground-state energy of symmetric nuclear matter does not correctly reproduce the properties of matter at saturation. With the nucleon-nucleon V low k one is unable to reach the densities needed for the calculation of neutron star masses. To circumvent this problem we use two approaches: in the first one, we parametrize the entire nucleonic sector. In the second one, we replace only the three-body force. The former will enable us to study neutron star masses, and the latter for studying the medium's response to the external probe. In this thesis we take the external probe to be the neutrino. By combining this parametrization with the YN V low k potential, we calculate the equation of state of equilibrated matter. Performing the calculation in the Hartree-Fock approximation at zero temperature, the concentrations of all particles are calculated. From these we can ascertain at which densities hyperons appear for a wide range of parameters. Finally, we calculate the masses of neutron stars with these concentrations. For the calculation of the medium's response to an external probe, we replace the three-body force with a density-dependent interaction. This

  10. Geometrical optics of dense aerosols: forming dense plasma slabs.

    Science.gov (United States)

    Hay, Michael J; Valeo, Ernest J; Fisch, Nathaniel J

    2013-11-01

    Assembling a freestanding, sharp-edged slab of homogeneous material that is much denser than gas, but much more rarefied than a solid, is an outstanding technological challenge. The solution may lie in focusing a dense aerosol to assume this geometry. However, whereas the geometrical optics of dilute aerosols is a well-developed field, the dense aerosol limit is mostly unexplored. Yet controlling the geometrical optics of dense aerosols is necessary in preparing such a material slab. Focusing dense aerosols is shown here to be possible, but the finite particle density reduces the effective Stokes number of the flow, a critical result for controlled focusing.

  11. Mercury's Densely Cratered Surface

    Science.gov (United States)

    1974-01-01

    Mariner 10 took this picture (FDS 27465) of the densely cratered surface of Mercury when the spacecraft was 18,200 kilometers (8085 miles) from the planet on March 29. The dark line across top of picture is a 'dropout' of a few TV lines of data. At lower left, a portion of a 61 kilometer (38 mile) crater shows a flow front extending across the crater floor and filling more than half of the crater. The smaller, fresh crater at center is about 25 kilometers (15 miles) in diameter. Craters as small as one kilometer (about one-half mile) across are visible in the picture.The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.Image Credit: NASA/JPL/Northwestern University

  12. Preparation and characterization of green-nano-composite material based on polyaniline, multiwalled carbon nano tubes and carboxymethyl cellulose: For electrochemical sensor applications.

    Science.gov (United States)

    Gautam, Vineeta; Singh, Karan Pratap; Yadav, Vijay Laxmi

    2018-06-01

    In this paper, we are presenting the preparation and characterization of "polyaniline/multiwalled carbon nanotubes/carboxymethyl cellulose" based novel composite material. It's morphological, thermal, structural, and electrochemical properties were investigated by using different instrumental techniques. During the in-situ chemical polymerization of aniline in the aqueous suspension of CMC and MWCNTs, the particle size change in two different ways "top to bottom" (low molecular weight oligomers grows in size) and "bottom to top" (long fibers of CMC fragmented in the reaction mixture). The combination of these two processes facilitated the fabrication of an integrated green-nano-composite material. In addition, a little amount of conductive nanofillers (MWCNTs) boosts the electrical and electrocatalytic properties of the material. Electron-rich centers of benzenoid rings exhibited π-π stacking with sp 2 carbon of MWCNTs. CMC dominantly impact on the properties of PANI, negatively charged carboxylate group of CMC ionically bonded with protonated amine/imine. FTIR and Raman analysis confirmed that the material has dominated quinoid units and effective charge transfer. Hydroxyl and carboxyl groups and bonded water molecules of CMC results in a network of hydrogen bonds (which induced directional property). PANI/MWCNTs/CMC have nanobead-like structures (TEM analysis), large surface area, large pore volume, small pore diameter (BET and BJH studies) and good dispersion ability in the aqueous phase. Nanostructures of aligned PANI exhibited excellent electrochemical properties have attracted increasing attention. Modified carbon paste electrode was used for electrocatalytic detection of ascorbic acid (as a model analyte). The sensor exhibited a linear range 0.05 mM-5 mM, sensitivity 100.63 μA mM -1  cm -2 , and limit of detection 0.01 mM. PANI/MWCNTs/CMC is suitable nanocomposite material for apply electroactive/conducting ink and membrane (which could be

  13. Hadrons in dense matter. Proceedings

    International Nuclear Information System (INIS)

    Buballa, M.; Noerenberg, W.; Schaefer, B.J.; Wambach, J.

    2000-03-01

    The following topics were dealt with: Elementary hadronic reactions, Delta dynamics in nuclei, in-medium s-wave ππ-correlations, strangeness in hot and dense matter, medium modifications of vector mesons and dilepton production, medium modifications of charmonium, thermal properties of hot and dense hadronic matter, nuclear matter, spectral functions and QCD sum rules

  14. Unified approach to dense matter

    International Nuclear Information System (INIS)

    Park, Byung-Yoon; Lee, Hee-Jung; Vento, Vicente; Kim, Joon-Il; Min, Dong-Pil; Rho, Mannque

    2005-01-01

    We apply the Skyrme model to dense hadronic matter, which provides a unified approach to high density, valid in the large N c limit. In our picture, dense hadronic matter is described by the classical soliton configuration with minimum energy for the given baryon number density. By incorporating the meson fluctuations on such ground state we obtain an effective Lagrangian for meson dynamics in a dense medium. Our starting point has been the Skyrme model defined in terms of pions, thereafter we have extended and improved the model by incorporating other degrees of freedom such as dilaton, kaons and vector mesons

  15. Nano-composite stainless steel

    Science.gov (United States)

    Dehoff, Ryan R.; Blue, Craig A.; Peter, William H.; Chen, Wei; Aprigliano, Louis F.

    2015-07-14

    A composite stainless steel composition is composed essentially of, in terms of wt. % ranges: 25 to 28 Cr; 11 to 13 Ni; 7 to 8 W; 3.5 to 4 Mo; 3 to 3.5 B; 2 to 2.5 Mn; 1 to 1.5 Si; 0.3 to 1.7 C; up to 2 O; balance Fe. The composition has an austenitic matrix phase and a particulate, crystalline dispersed phase.

  16. Dual Delivery of BMP-2 and bFGF from a New Nano-Composite Scaffold, Loaded with Vascular Stents for Large-Size Mandibular Defect Regeneration

    Directory of Open Access Journals (Sweden)

    Hang Zhao

    2013-06-01

    Full Text Available The aim of this study was to investigate the feasibility and advantages of the dual delivery of bone morphogenetic protein-2 (BMP-2 and basic fibroblast growth factor (bFGF from nano-composite scaffolds (PLGA/PCL/nHA loaded with vascular stents (PLCL/Col/nHA for large bone defect regeneration in rabbit mandibles. Thirty-six large bone defects were repaired in rabbits using engineering bone composed of allogeneic bone marrow mesenchymal stem cells (BMSCs, bFGF, BMP-2 and scaffolds composed of PLGA/PCL/nHA loaded with PLCL/Col/nHA. The experiments were divided into six groups: BMSCs/bFGF/BMP-2/scaffold, BMSCs/BMP-2/scaffold, BMSCs/bFGF/scaffold, BMSCs/scaffold, scaffold alone and no treatment. Sodium alginate hydrogel was used as the carrier for BMP-2 and bFGF and its features, including gelling, degradation and controlled release properties, was detected by the determination of gelation and degradation time coupled with a controlled release study of bovine serum albumin (BSA. AlamarBlue assay and alkaline phosphatase (ALP activity were used to evaluate the proliferation and osteogenic differentiation of BMSCs in different groups. X-ray and histological examinations of the samples were performed after 4 and 12 weeks post-implantation to clarify new bone formation in the mandible defects. The results verified that the use of sodium alginate hydrogel as a controlled release carrier has good sustained release ability, and the combined application of bFGF and BMP-2 could significantly promote the proliferation and osteogenic differentiation of BMSCs (p < 0.05 or p < 0.01. In addition, X-ray and histological examinations of the samples exhibited that the dual release group had significantly higher bone formation than the other groups. The above results indicate that the delivery of both growth factors could enhance new bone formation and vascularization compared with delivery of BMP-2 or bFGF alone, and may supply a promising way of repairing large

  17. Dual mode emission and harmonic generation in ZnO-CaO-Al{sub 2}O{sub 3}: Er{sup 3+} nano-composite

    Energy Technology Data Exchange (ETDEWEB)

    Verma, R.K. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Kumar, K. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India); Nano-technology Application Centre, University of Allahabad, Allahabad (India); Rai, S.B., E-mail: sbrai49@yahoo.co.i [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, Varanasi 221005 (India)

    2011-05-15

    Er{sup 3+} doped ZnO-CaO-Al{sub 2}O{sub 3} nano-composite phosphor has been synthesized through combustion method and its emission and harmonic generation properties have been studied. The X-ray diffraction and thermal analysis techniques have been used to prove the dual phase (ZnO and CaO-Al{sub 2}O{sub 3}) nature of the phosphor. The phosphor has shown up-conversion emission on near-infra-red (976 nm) excitation and down-conversion emission on 355 nm excitation in presence of Er{sup 3+} and thus behaves as a dual mode phosphor. On excitation with 976 nm diode laser, material shows color tunability (calcination of composite material at different temperatures). Formation of ZnO nanocrystals on heat treatment of as-synthesized sample has shown its characteristic emission at 388 nm and also the energy transfer from ZnO to Er{sup 3+} ions. The low temperature emission measurements have been carried out and the results have been discussed. Phosphor has shown strong second harmonic generation (SHG) at 532 nm on 1064 nm and at 266 nm on 532 nm excitation. - Research highlights: {yields} We have synthesized Er{sup 3+} doped composite material by combustion method. The two phases of composites are ZnO and CaO-Al{sub 2}O{sub 3}. {yields} The phosphor has shown up-conversion emission on near-infra-red (976 nm) excitation and down-conversion emission on 355 nm excitation in presence of Er{sup 3+} and thus behaves as a dual mode phosphor. This material also shows colour tenability on excitation of 976 nm diode laser at different temperature calcinations (i.e., As-synthesized to calcinated at 1473 K). {yields} Low temperature effects on Er{sup 3+} as well as ZnO emission have been carried out. We observed that at low temperature the efficiency of Er{sup 3+} increases while in the case of ZnO its intensity increases and also 12 nm shifting observed. {yields} Composite material has shown strong second harmonic generation (SHG) at 532 nm on 1064 nm and at 266 nm on 532 nm

  18. Transport properties of dense matter

    International Nuclear Information System (INIS)

    Itoh, Naoki; Mitake, Shinichi; Iyetomi, Hiroshi; Ichimaru, Setsuo

    1983-01-01

    Transport coefficients, electrical and thermal conductivities in particular, are essential physical quantities for the theories of stellar structure. Since the discoveries of pulsars and X-ray stars, an accurate evaluation of the transport coefficients in the dense matter has become indispensable to the quantitative understanding of the observed neutron stars. The authors present improved calculations of the electrical and thermal conductivities of the dense matter in the liquid metal phase, appropriate to white dwarfs and neutron stars. (Auth.)

  19. Preparation and characterization of functionalized cellulose nano crystals with methyl adipoyl chloride used to prepare chitosan grafting nano composite; Preparacao e caracterizacao de nanocristais de celulose funcionalizados com CMA utilizados na preparacao de nanocomposito de quitosana reticulado

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Joao Paulo de; Teixeira, Ivo F; Donnici, Claudio L; Pereira, Fabiano V [Universidade Federal de Minas Gerais - UFMG, Belo Horizonte, MG (Brazil)

    2011-07-01

    Cellulose nano crystals (CNCs) were prepared from eucalyptus pulp and functionalized with methyl adipoyl chloride. The nano materials were characterized by different techniques including FTIR, 1H NMR and XRD which showed that the functionalization occurs only on the surface of the nano structures without change in crystalline structure of the nanoparticles. The new-functionalized CNCs were used as reinforcement in the preparation of a nano composite with chitosan, through the formation of a covalent bond between the nano filler and matrix. Preliminary results of mechanical tests indicate an improvement in tensile strength and increase in deformation of chitosan. (author)

  20. Synthesis and characterization of poly-o-anisidine Sn(IV tungstate: A new and novel ‘organic–inorganic’ nano-composite material and its electro-analytical applications as Hg(II ion-selective membrane electrode

    Directory of Open Access Journals (Sweden)

    Asif A. Khan

    2012-07-01

    Full Text Available An organic–inorganic nano-composite poly-o-anisidine Sn(IV tungstate was chemically synthesized by sol–gel mixing of the incorporation of organic polymer o-anisidine into the matrices of inorganic ppt of Sn(IV tungstate in different mixing volume ratios. This composite material has been characterized using various analytical techniques like XRD (X-ray diffraction, FTIR (Fourier transform infrared, SEM (Scanning electron microscopy, TEM (Transmission electron microscopy and simultaneous TGA (Thermogravimetric analysis studies. On the basis of distribution studies, the material was found to be highly selective for Hg(II. Using this nano-composite cation exchanger as electro-active material, a new heterogeneous precipitate based on ion-sensitive membrane electrode was developed for the determination of Hg(II ions in solutions. The membrane electrode was mechanically stable, with a quick response time, and can be operated within a wide pH range. The electrode was also found to be satisfactory in electrometric titrations.

  1. The study of structural properties of carbon nanotubes decorated with NiFe₂O₄ nanoparticles and application of nano-composite thin film as H₂S gas sensor.

    Science.gov (United States)

    Hajihashemi, R; Rashidi, Ali M; Alaie, M; Mohammadzadeh, R; Izadi, N

    2014-11-01

    Nano-composite of multiwall carbon nanotube, decorated with NiFe2O4 nanoparticles (NiFe2O4-MWCNT), was synthesized using the sol-gel method. NiFe2O4-MWCNTs were characterized using different methods such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM). The average size of the crystallites is 23.93 nm. The values of the saturation magnetization (MS), coercivity (HC) and retentivity (MR) of NiFe2O4-MWCNTs are obtained as 15 emu g(-1), 21Oe and 5 emu g(-1), respectively. In this research, NiFe2O4-MWCNT thin films were prepared with the spin-coating method. These thin films were used as the H2S gas sensor. The results suggest the possibility of the utilization of NiFe2O4-MWCNT nano-composite, as the H2S detector. The sensor shows appropriate response towards 100 ppm of H2S at 300°C. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Cobalt ferrite nano-composite coated on glass by Doctor Blade method for photo-catalytic degradation of an azo textile dye Reactive Red 4: XRD, FESEM and DRS investigations.

    Science.gov (United States)

    Habibi, Mohammad Hossein; Parhizkar, Janan

    2015-11-05

    Cobalt ferrite nano-composite was prepared by hydrothermal route using cobalt nitrate, iron nitrate and ethylene glycol as chelating agent. The nano-composite was coated on glass by Doctor Blade method and annealed at 300 °C. The structural, optical, and photocatalytic properties have been studied by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-visible spectroscopy (UV-Vis DRS). Powder XRD analysis confirmed formation of CoFe2O4 spinel phase. The estimated particle size from FESEM data was 50 nm. The calculated energy band gaps, obtained by Tauc relation from UV-Vis absorption spectra was 1.3 eV. Photocatalytic degradation of Reactive Red 4 as an azo textile was investigated in aqueous solution under irradiation showed 68.0% degradation of the dye within 100 min. The experimental enhanced activity compare to pure Fe2O3 can be ascribed to the formation of composite, which was mainly attributable to the transfer of electron and hole to the surface of composite and hinder the electron hole recombination. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Effect of annealing temperature on optical properties of binary zinc tin oxide nano-composite prepared by sol-gel route using simple precursors: structural and optical studies by DRS, FT-IR, XRD, FESEM investigations.

    Science.gov (United States)

    Habibi, Mohammad Hossein; Mardani, Maryam

    2015-02-25

    Binary zinc tin oxide nano-composite was synthesized by a facile sol-gel method using simple precursors from the solutions consisting of zinc acetate, tin(IV) chloride and ethanol. Effect of annealing temperature on optical and structural properties was investigated using X-ray diffraction (XRD), diffuse reflectance spectra (DRS), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). XRD results revealed the existence of the ZnO and SnO2 phases. FESEM results showed that binary zinc tin oxide nano-composites ranges from 56 to 60 nm in diameter at 400°C and 500°C annealing temperatures respectively. The optical band gap was increased from 2.72 eV to 3.11 eV with the increasing of the annealing temperature. FTIR results confirmed the presence of zinc oxide and tin oxide and the broad absorption peaks at 3426 and 1602 cm(-1) can be ascribed to the vibration of absorptive water, and the absorption peaks at 546, 1038 and 1410 cm(-1) are due to the vibration of Zn-O or Sn-O groups in binary zinc tin oxide. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Extremely fine structured cathode for solid oxide fuel cells using Sr-doped LaMnO3 and Y2O3-stabilized ZrO2 nano-composite powder synthesized by spray pyrolysis

    Science.gov (United States)

    Shimada, Hiroyuki; Yamaguchi, Toshiaki; Sumi, Hirofumi; Nomura, Katsuhiro; Yamaguchi, Yuki; Fujishiro, Yoshinobu

    2017-02-01

    A solid oxide fuel cell (SOFC) for high power density operation was developed with a microstructure-controlled cathode using a nano-composite powder of Sr-doped LaMnO3 (LSM) and Y2O3-stabilized ZrO2 (YSZ) synthesized by spray pyrolysis. The individual LSM-YSZ nano-composite particles, formed by crystalline and amorphous nano-size LSM and YSZ particles, showed spherical morphology with uniform particle size. The use of this powder for cathode material led to an extremely fine microstructure, in which all the LSM and YSZ grains (approximately 100-200 nm) were highly dispersed and formed their own network structures. This microstructure was due to the two phase electrode structure control using the powder, namely, nano-order level in each particle and micro-order level between particles. An anode-supported SOFC with the LSM-YSZ cathode using humidified H2 as fuel and ambient air as oxidant exhibited high power densities, such as 1.29 W cm-2 under a voltage of 0.75 V and a maximum power density of 2.65 W cm-2 at 800 °C. Also, the SOFC could be stably operated for 250 h with no degradation, even at a high temperature of 800 °C.

  5. Dynamics of dense particle disks

    International Nuclear Information System (INIS)

    Araki, S.; Tremaine, S.; Toronto Univ., Canada)

    1986-01-01

    The present investigation of mechanical equilibrium and collisional transport processes in dense, differentially rotating particle disks is based on the Enskog (1922) theory of dense, hard sphere gases, with the single exception that the spheres are inelastic. The viscous instability suggested as a source of Saturn B ring structure does not arise in the models presented, although the ring may be subject to a phase transition analogous to the liquid-solid transition observed in molecular dynamics simulations of elastic hard spheres. In such a case, the ring would alternately exhibit zero-shear, or solid, and high shear, or liquid, zones. 29 references

  6. Transiting exoplanets from the CoRoT space mission . XIII. CoRoT-13b: a dense hot Jupiter in transit around a star with solar metallicity and super-solar lithium content

    Science.gov (United States)

    Cabrera, J.; Bruntt, H.; Ollivier, M.; Díaz, R. F.; Csizmadia, Sz.; Aigrain, S.; Alonso, R.; Almenara, J.-M.; Auvergne, M.; Baglin, A.; Barge, P.; Bonomo, A. S.; Bordé, P.; Bouchy, F.; Carone, L.; Carpano, S.; Deleuil, M.; Deeg, H. J.; Dvorak, R.; Erikson, A.; Ferraz-Mello, S.; Fridlund, M.; Gandolfi, D.; Gazzano, J.-C.; Gillon, M.; Guenther, E. W.; Guillot, T.; Hatzes, A.; Havel, M.; Hébrard, G.; Jorda, L.; Léger, A.; Llebaria, A.; Lammer, H.; Lovis, C.; Mazeh, T.; Moutou, C.; Ofir, A.; von Paris, P.; Pätzold, M.; Queloz, D.; Rauer, H.; Rouan, D.; Santerne, A.; Schneider, J.; Tingley, B.; Titz-Weider, R.; Wuchterl, G.

    2010-11-01

    We announce the discovery of the transiting planet CoRoT-13b. Ground-based follow-up in CFHT and IAC80 confirmed CoRoT's observations. The mass of the planet was measured with the HARPS spectrograph and the properties of the host star were obtained analyzing HIRES spectra from the Keck telescope. It is a hot Jupiter-like planet with an orbital period of 4.04 days, 1.3 Jupiter masses, 0.9 Jupiter radii, and a density of 2.34 g cm-3. It orbits a G0V star with T_eff = 5 945 K, M* = 1.09 M⊙, R_* = 1.01 R⊙, solar metallicity, a lithium content of + 1.45 dex, and an estimated age of between 0.12 and 3.15 Gyr. The lithium abundance of the star is consistent with its effective temperature, activity level, and age range derived from the stellar analysis. The density of the planet is extreme for its mass, implies that heavy elements are present with a mass of between about 140 and 300 {M}⊕. The CoRoT space mission, launched on December 27th 2006, has been developed and is operated by CNES, with the contribution of Austria, Belgium, Brazil, ESA (RSSD and Science Programme), Germany and Spain. Part of the observations were obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. Based on observations made with HARPS spectrograph on the 3.6-m European Organisation for Astronomical Research in the Southern Hemisphere telescope at La Silla Observatory, Chile (ESO program 184.C-0639). Based on observations made with the IAC80 telescope operated on the island of Tenerife by the Instituto de Astrofísica de Canarias in the Spanish Observatorio del Teide. Part of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics

  7. Dense Crowds of Virtual Humans

    NARCIS (Netherlands)

    Stüvel, S.A.

    2016-01-01

    This thesis presents a novel crowd simulation method `Torso Crowds', aimed at the simulation of dense crowds. The method is based on the results of user studies and a motion capture experiment, which are also described in this thesis. Torso Crowds introduces a capsule shape to represent people in

  8. Warm Dense Matter: An Overview

    International Nuclear Information System (INIS)

    Kalantar, D H; Lee, R W; Molitoris, J D

    2004-01-01

    This document provides a summary of the ''LLNL Workshop on Extreme States of Materials: Warm Dense Matter to NIF'' which was held on 20, 21, and 22 February 2002 at the Wente Conference Center in Livermore, CA. The warm dense matter regime, the transitional phase space region between cold material and hot plasma, is presently poorly understood. The drive to understand the nature of matter in this regime is sparking scientific activity worldwide. In addition to pure scientific interest, finite temperature dense matter occurs in the regimes of interest to the SSMP (Stockpile Stewardship Materials Program). So that obtaining a better understanding of WDM is important to performing effective experiments at, e.g., NIF, a primary mission of LLNL. At this workshop we examined current experimental and theoretical work performed at, and in conjunction with, LLNL to focus future activities and define our role in this rapidly emerging research area. On the experimental front LLNL plays a leading role in three of the five relevant areas and has the opportunity to become a major player in the other two. Discussion at the workshop indicated that the path forward for the experimental efforts at LLNL were two fold: First, we are doing reasonable baseline work at SPLs, HE, and High Energy Lasers with more effort encouraged. Second, we need to plan effectively for the next evolution in large scale facilities, both laser (NIF) and Light/Beam sources (LCLS/TESLA and GSI) Theoretically, LLNL has major research advantages in areas as diverse as the thermochemical approach to warm dense matter equations of state to first principles molecular dynamics simulations. However, it was clear that there is much work to be done theoretically to understand warm dense matter. Further, there is a need for a close collaboration between the generation of verifiable experimental data that can provide benchmarks of both the experimental techniques and the theoretical capabilities. The conclusion of this

  9. Holographic Renormalization in Dense Medium

    International Nuclear Information System (INIS)

    Park, Chanyong

    2014-01-01

    The holographic renormalization of a charged black brane with or without a dilaton field, whose dual field theory describes a dense medium at finite temperature, is investigated in this paper. In a dense medium, two different thermodynamic descriptions are possible due to an additional conserved charge. These two different thermodynamic ensembles are classified by the asymptotic boundary condition of the bulk gauge field. It is also shown that in the holographic renormalization regularity of all bulk fields can reproduce consistent thermodynamic quantities and that the Bekenstein-Hawking entropy is nothing but the renormalized thermal entropy of the dual field theory. Furthermore, we find that the Reissner-Nordström AdS black brane is dual to a theory with conformal matter as expected, whereas a charged black brane with a nontrivial dilaton profile is mapped to a theory with nonconformal matter although its leading asymptotic geometry still remains as AdS space

  10. Suprathermal viscosity of dense matter

    International Nuclear Information System (INIS)

    Alford, Mark; Mahmoodifar, Simin; Schwenzer, Kai

    2010-01-01

    Motivated by the existence of unstable modes of compact stars that eventually grow large, we study the bulk viscosity of dense matter, taking into account non-linear effects arising in the large amplitude regime, where the deviation μ Δ of the chemical potentials from chemical equilibrium fulfills μ Δ > or approx. T. We find that this supra-thermal bulk viscosity can provide a potential mechanism for saturating unstable modes in compact stars since the viscosity is strongly enhanced. Our study confirms previous results on strange quark matter and shows that the suprathermal enhancement is even stronger in the case of hadronic matter. We also comment on the competition of different weak channels and the presence of suprathermal effects in various color superconducting phases of dense quark matter.

  11. Dilute and dense axion stars

    Science.gov (United States)

    Visinelli, Luca; Baum, Sebastian; Redondo, Javier; Freese, Katherine; Wilczek, Frank

    2018-02-01

    Axion stars are hypothetical objects formed of axions, obtained as localized and coherently oscillating solutions to their classical equation of motion. Depending on the value of the field amplitude at the core |θ0 | ≡ | θ (r = 0) |, the equilibrium of the system arises from the balance of the kinetic pressure and either self-gravity or axion self-interactions. Starting from a general relativistic framework, we obtain the set of equations describing the configuration of the axion star, which we solve as a function of |θ0 |. For small |θ0 | ≲ 1, we reproduce results previously obtained in the literature, and we provide arguments for the stability of such configurations in terms of first principles. We compare qualitative analytical results with a numerical calculation. For large amplitudes |θ0 | ≳ 1, the axion field probes the full non-harmonic QCD chiral potential and the axion star enters the dense branch. Our numerical solutions show that in this latter regime the axions are relativistic, and that one should not use a single frequency approximation, as previously applied in the literature. We employ a multi-harmonic expansion to solve the relativistic equation for the axion field in the star, and demonstrate that higher modes cannot be neglected in the dense regime. We interpret the solutions in the dense regime as pseudo-breathers, and show that the life-time of such configurations is much smaller than any cosmological time scale.

  12. Formulation and characterization of polyethylenes and organo-clays. Barrier properties of the obtained nano-composites; Formulation et caracterisation de polyethylenes charges avec des argiles. Proprietes barriere des nanocomposites obtenus

    Energy Technology Data Exchange (ETDEWEB)

    Wache, R

    2004-10-01

    The particularity of polymer layered silicate nano-composites is based on the exfoliation of the clay platelets in the polymer matrix. Therefore properties may be dramatically modified with very low clay loading. In this work polyethylene and organo-clay have been melt blended. Due to a lack of polarity, the polymer chains do not intercalate the clay stacking. However exfoliation is achieved using maleate polyethylene. We used this polymer as a compatibilizer to promote clay exfoliation in the polyethylene matrix. Partial exfoliation is obtained. Barrier properties of these materials have been characterized. Permeability is higher for the clay reinforced products than their matrix. To understand the poor permeability results a tortuosity model has been developed. The quality of the interface seems to be involved. Several organo-clays and compatibilizers have been tested to improve it. But for the concentrations of these products used polyethylene clay interactions always exist and lead to an increase of diffusion. (author)

  13. Synthesis and magnetic properties of hard magnetic (CoFe{sub 2}O{sub 4})-soft magnetic (Fe{sub 3}O{sub 4}) nano-composite ceramics by SPS technology

    Energy Technology Data Exchange (ETDEWEB)

    Fei Chunlong [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Zhang Yue [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); Yang Zhi; Liu Yong [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); Xiong Rui, E-mail: wudawujiron@163.co [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China) and Key Laboratory for the Green Preparation and Application of Functional Materials of Ministry of Education, Hubei University, Wuhan 430062 (China); Shi Jing [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China); International Center for Materials Physics, Shen Yang 110015 (China); Ruan Xuefeng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Hubei Key Laboratory on Organic and Polymeric Opto-electronic Materials, Wuhan University, Wuhan 430072 (China)

    2011-07-15

    CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} nano-composite ceramics were synthesized by Spark Plasma Sintering. The X-ray diffraction patterns show that all samples are composed of CoFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} phases when the sintering temperature is below 900 {sup o}C. It is found that the magnetic properties strongly depend on the sintering temperature. The two-step hysteresis loops for samples sintered below 500 {sup o}C are observed, but when sintering temperature reaches 500 {sup o}C, the step disappears, which indicates that the CoFe{sub 2}O{sub 4} and Fe{sub 3}O{sub 4} are well exchange coupled. As the sintering temperature increases from 500 to 800 {sup o}C, the results of X-ray diffractometer indicate the constriction of crystalline regions due to the ion diffusion at the interfaces of CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} phases, which have great impact on the magnetic properties. - Research highlights: In this work, a series of CoFe{sub 2}O{sub 4}/Fe{sub 3}O{sub 4} nano-composite ceramics were prepared through SPS. The magnetic properties of these ceramics have been studied in detail. It is found that the magnetic properties strongly depend on the sintering temperature.

  14. Dense Breasts: Answers to Commonly Asked Questions

    Science.gov (United States)

    ... Cancer Prevention Genetics of Breast & Gynecologic Cancers Breast Cancer Screening Research Dense Breasts: Answers to Commonly Asked Questions What are dense breasts? Breasts contain glandular, connective, and fat tissue. Breast density is a term that describes the ...

  15. Constructing Dense Graphs with Unique Hamiltonian Cycles

    Science.gov (United States)

    Lynch, Mark A. M.

    2012-01-01

    It is not difficult to construct dense graphs containing Hamiltonian cycles, but it is difficult to generate dense graphs that are guaranteed to contain a unique Hamiltonian cycle. This article presents an algorithm for generating arbitrarily large simple graphs containing "unique" Hamiltonian cycles. These graphs can be turned into dense graphs…

  16. Screening in dense ionic fluids

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1991-01-01

    There has been great progress in recent years in determining and understanding the structure of molten salts. I focus on molten alkali halides and discuss two main points concerning their liquid structure and its relationship with static electrical response in these dense ionic conductors. These are (i) the nature of screening and the related definitions and properties of the screening length and of the dielectric function, and (ii) developments in integral equations techniques for the evaluation of molten salt structure and static screening from given pair potentials. (author). 26 refs, 3 figs, 2 tabs

  17. Deterministic and unambiguous dense coding

    International Nuclear Information System (INIS)

    Wu Shengjun; Cohen, Scott M.; Sun Yuqing; Griffiths, Robert B.

    2006-01-01

    Optimal dense coding using a partially-entangled pure state of Schmidt rank D and a noiseless quantum channel of dimension D is studied both in the deterministic case where at most L d messages can be transmitted with perfect fidelity, and in the unambiguous case where when the protocol succeeds (probability τ x ) Bob knows for sure that Alice sent message x, and when it fails (probability 1-τ x ) he knows it has failed. Alice is allowed any single-shot (one use) encoding procedure, and Bob any single-shot measurement. For D≤D a bound is obtained for L d in terms of the largest Schmidt coefficient of the entangled state, and is compared with published results by Mozes et al. [Phys. Rev. A71, 012311 (2005)]. For D>D it is shown that L d is strictly less than D 2 unless D is an integer multiple of D, in which case uniform (maximal) entanglement is not needed to achieve the optimal protocol. The unambiguous case is studied for D≤D, assuming τ x >0 for a set of DD messages, and a bound is obtained for the average . A bound on the average requires an additional assumption of encoding by isometries (unitaries when D=D) that are orthogonal for different messages. Both bounds are saturated when τ x is a constant independent of x, by a protocol based on one-shot entanglement concentration. For D>D it is shown that (at least) D 2 messages can be sent unambiguously. Whether unitary (isometric) encoding suffices for optimal protocols remains a major unanswered question, both for our work and for previous studies of dense coding using partially-entangled states, including noisy (mixed) states

  18. Breaking Dense Structures: Proving Stability of Densely Structured Hybrid Systems

    Directory of Open Access Journals (Sweden)

    Eike Möhlmann

    2015-06-01

    Full Text Available Abstraction and refinement is widely used in software development. Such techniques are valuable since they allow to handle even more complex systems. One key point is the ability to decompose a large system into subsystems, analyze those subsystems and deduce properties of the larger system. As cyber-physical systems tend to become more and more complex, such techniques become more appealing. In 2009, Oehlerking and Theel presented a (de-composition technique for hybrid systems. This technique is graph-based and constructs a Lyapunov function for hybrid systems having a complex discrete state space. The technique consists of (1 decomposing the underlying graph of the hybrid system into subgraphs, (2 computing multiple local Lyapunov functions for the subgraphs, and finally (3 composing the local Lyapunov functions into a piecewise Lyapunov function. A Lyapunov function can serve multiple purposes, e.g., it certifies stability or termination of a system or allows to construct invariant sets, which in turn may be used to certify safety and security. In this paper, we propose an improvement to the decomposing technique, which relaxes the graph structure before applying the decomposition technique. Our relaxation significantly reduces the connectivity of the graph by exploiting super-dense switching. The relaxation makes the decomposition technique more efficient on one hand and on the other allows to decompose a wider range of graph structures.

  19. Optimal super dense coding over memory channels

    OpenAIRE

    Shadman, Zahra; Kampermann, Hermann; Macchiavello, Chiara; Bruß, Dagmar

    2011-01-01

    We study the super dense coding capacity in the presence of quantum channels with correlated noise. We investigate both the cases of unitary and non-unitary encoding. Pauli channels for arbitrary dimensions are treated explicitly. The super dense coding capacity for some special channels and resource states is derived for unitary encoding. We also provide an example of a memory channel where non-unitary encoding leads to an improvement in the super dense coding capacity.

  20. Dense module enumeration in biological networks

    Science.gov (United States)

    Tsuda, Koji; Georgii, Elisabeth

    2009-12-01

    Analysis of large networks is a central topic in various research fields including biology, sociology, and web mining. Detection of dense modules (a.k.a. clusters) is an important step to analyze the networks. Though numerous methods have been proposed to this aim, they often lack mathematical rigorousness. Namely, there is no guarantee that all dense modules are detected. Here, we present a novel reverse-search-based method for enumerating all dense modules. Furthermore, constraints from additional data sources such as gene expression profiles or customer profiles can be integrated, so that we can systematically detect dense modules with interesting profiles. We report successful applications in human protein interaction network analyses.

  1. Dense module enumeration in biological networks

    International Nuclear Information System (INIS)

    Tsuda, Koji; Georgii, Elisabeth

    2009-01-01

    Analysis of large networks is a central topic in various research fields including biology, sociology, and web mining. Detection of dense modules (a.k.a. clusters) is an important step to analyze the networks. Though numerous methods have been proposed to this aim, they often lack mathematical rigorousness. Namely, there is no guarantee that all dense modules are detected. Here, we present a novel reverse-search-based method for enumerating all dense modules. Furthermore, constraints from additional data sources such as gene expression profiles or customer profiles can be integrated, so that we can systematically detect dense modules with interesting profiles. We report successful applications in human protein interaction network analyses.

  2. Dense sheet Z-pinches

    International Nuclear Information System (INIS)

    Tetsu, Miyamoto

    1999-01-01

    The steady state and quasi-steady processes of infinite- and finite-width sheet z-pinches are studied. The relations corresponding to the Bennett relation and Pease-Braginskii current of cylindrical fiber z-pinches depend on a geometrical factor in the sheet z-pinches. The finite-width sheet z-pinch is approximated by a segment of infinite-width sheet z-pinch, if it is wide enough, and corresponds to a number of (width/thickness) times fiber z-pinch plasmas of the diameter that equals the sheet thickness. If the sheet current equals this number times the fiber current, the plasma created in the sheet z-pinches is as dense as in the fiber z-pinches. The total energy of plasma and magnetic field per unit mass is approximately equal in both pinches. Quasi-static transient processes are different in several aspects from the fiber z-pinch. No radiation collapse occurs in the sheet z-pinch. The stability is improved in the sheet z-pinches. The fusion criterions and the experimental arrangements to produce the sheet z-pinches are also discussed. (author)

  3. STAR FORMATION IN DENSE CLUSTERS

    International Nuclear Information System (INIS)

    Myers, Philip C.

    2011-01-01

    A model of core-clump accretion with equally likely stopping describes star formation in the dense parts of clusters, where models of isolated collapsing cores may not apply. Each core accretes at a constant rate onto its protostar, while the surrounding clump gas accretes as a power of protostar mass. Short accretion flows resemble Shu accretion and make low-mass stars. Long flows resemble reduced Bondi accretion and make massive stars. Accretion stops due to environmental processes of dynamical ejection, gravitational competition, and gas dispersal by stellar feedback, independent of initial core structure. The model matches the field star initial mass function (IMF) from 0.01 to more than 10 solar masses. The core accretion rate and the mean accretion duration set the peak of the IMF, independent of the local Jeans mass. Massive protostars require the longest accretion durations, up to 0.5 Myr. The maximum protostar luminosity in a cluster indicates the mass and age of its oldest protostar. The distribution of protostar luminosities matches those in active star-forming regions if protostars have a constant birthrate but not if their births are coeval. For constant birthrate, the ratio of young stellar objects to protostars indicates the star-forming age of a cluster, typically ∼1 Myr. The protostar accretion luminosity is typically less than its steady spherical value by a factor of ∼2, consistent with models of episodic disk accretion.

  4. Preparation of Nd-Fe-B/α-Fe nano-composite thick-film magnets on various substrates using PLD with high laser energy density above 10 J/cm2

    Science.gov (United States)

    Nakano, M.; Kondo, H.; Yamashita, A.; Yanai, T.; Itakura, M.; Fukunaga, H.

    2018-05-01

    PLD (Pulsed Laser Deposition) method with high laser energy density (LED) above 10 J/cm2 followed by a flash annealing enabled us to obtain isotropic nano-composite thick-film magnets with (BH)max ≧ 80 kJ/m3 on polycrystalline Ta substrates. We also have demonstrated that a dispersed structure composed of α-Fe together with Nd2Fe14B phases with the average grain diameter of approximately 20 nm could be formed on the Ta substrates. In this study, we tried to enhance the (BH)max value by controlling the microstructure due to the usage of different metal based substrates with each high melting point such as Ti, Nb, and W. Although it was difficult to vary the microstructure and to improve the magnetic properties of the films deposited on the substrates, we confirmed that isotropic thick-film magnets with (BH)max ≧ 80 kJ/m3 based on the nano-dispersed α-Fe and Nd2Fe14B phases could be obtained on various metal substrates with totally different polycrystalline structure. On the other hand, the use of a glass substrate lead to the deterioration of magnetic properties of a film prepared using the same preparation process.

  5. Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

    International Nuclear Information System (INIS)

    Mansoori, Y.; Darvishi, K.

    2014-01-01

    New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T g . In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

  6. Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

    Energy Technology Data Exchange (ETDEWEB)

    Mansoori, Y.; Darvishi, K., E-mail: ya_mansoori@yahoo.com [University of Mohaghegh Ardabili, Faculty of Science, Department of Applied Chemistry, Daneshgah, Ardabil (Iran, Islamic Republic of)

    2014-10-01

    New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T{sub g}. In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

  7. Dense image correspondences for computer vision

    CERN Document Server

    Liu, Ce

    2016-01-01

    This book describes the fundamental building-block of many new computer vision systems: dense and robust correspondence estimation. Dense correspondence estimation techniques are now successfully being used to solve a wide range of computer vision problems, very different from the traditional applications such techniques were originally developed to solve. This book introduces the techniques used for establishing correspondences between challenging image pairs, the novel features used to make these techniques robust, and the many problems dense correspondences are now being used to solve. The book provides information to anyone attempting to utilize dense correspondences in order to solve new or existing computer vision problems. The editors describe how to solve many computer vision problems by using dense correspondence estimation. Finally, it surveys resources, code, and data necessary for expediting the development of effective correspondence-based computer vision systems.   ·         Provides i...

  8. Composite systems of dilute and dense couplings

    International Nuclear Information System (INIS)

    Raymond, J R; Saad, D

    2008-01-01

    Composite systems, where couplings are of two types, a combination of strong dilute and weak dense couplings of Ising spins, are examined through the replica method. The dilute and dense parts are considered to have independent canonical disordered or uniform bond distributions; mixing the models by variation of a parameter γ alongside inverse temperature β we analyse the respective thermodynamic solutions. We describe the variation in high temperature transitions as mixing occurs; in the vicinity of these transitions we exactly analyse the competing effects of the dense and sparse models. By using the replica symmetric ansatz and population dynamics we described the low temperature behaviour of mixed systems

  9. Intense, ultrashort light and dense, hot matter

    Indian Academy of Sciences (India)

    tiphoton and tunneling ionization, the physics of plasma formed in dense matter is .... A typical Gaussian laser pulse of 100 fs dura- .... J range) – and finally it is compressed back to its .... bond-hardening, molecular orientation and reori-.

  10. Finding dense locations in indoor tracking data

    DEFF Research Database (Denmark)

    Ahmed, Tanvir; Pedersen, Torben Bach; Lu, Hua

    2014-01-01

    for semi-constrained indoor movement, and then uses this to map raw tracking records into mapping records representing object entry and exit times in particular locations. Then, an efficient indexing structure, the Dense Location Time Index (DLT-Index) is proposed for indexing the time intervals...... of the mapping table, along with associated construction, query processing, and pruning techniques. The DLT-Index supports very efficient aggregate point queries, interval queries, and dense location queries. A comprehensive experimental study with real data shows that the proposed techniques can efficiently......Finding the dense locations in large indoor spaces is very useful for getting overloaded locations, security, crowd management, indoor navigation, and guidance. Indoor tracking data can be very large and are not readily available for finding dense locations. This paper presents a graph-based model...

  11. Interference Coordination for Dense Wireless Networks

    DEFF Research Database (Denmark)

    Soret, Beatriz; Pedersen, Klaus I.; Jørgensen, Niels T.K.

    2015-01-01

    and dense deployment in Tokyo are compared. Evolution to DenseNets offers new opportunities for further development of downlink interference cooperation techniques. Various mechanisms in LTE and LTE-Advanced are revisited. Some techniques try to anticipate the future in a proactive way, whereas others......The promise of ubiquitous and super-fast connectivity for the upcoming years will be in large part fulfilled by the addition of base stations and spectral aggregation. The resulting very dense networks (DenseNets) will face a number of technical challenges. Among others, the interference emerges...... as an old acquaintance with new significance. As a matter of fact, the interference conditions and the role of aggressor and victim depend to a large extent on the density and the scenario. To illustrate this, downlink interference statistics for different 3GPP simulation scenarios and a more irregular...

  12. Skyrmions, dense matter and nuclear forces

    International Nuclear Information System (INIS)

    Pethick, C.J.

    1984-12-01

    A simple introduction to a number of properties of Skyrme's chiral soliton model of baryons is given. Some implications of the model for dense matter and for nuclear interactions are discussed. (orig.)

  13. Spherically symmetric relativistic model for spiral galaxies and dense stars

    International Nuclear Information System (INIS)

    Hojman, R.; Rodrigues, L.M.C.; Sasse, F.D.

    1990-01-01

    The behaviour of the pressure and the density as well as the gravitational field of a dense star are studied in some detail. For such a purpose and to take into account relativistic effects, we find a family of exact solutions of the Tolman-Oppenheimer-Volkov equation, which contains as a particular case solutions corresponding to a γ-law equation of state. The mentioned family can also be used to model the (luminous or dark) matter content of spiral galaxies, as it fits the observed data for their orbital velocities profiles. (author)

  14. Dynamical theory of dense groups of galaxies

    Science.gov (United States)

    Mamon, Gary A.

    1990-01-01

    It is well known that galaxies associate in groups and clusters. Perhaps 40% of all galaxies are found in groups of 4 to 20 galaxies (e.g., Tully 1987). Although most groups appear to be so loose that the galaxy interactions within them ought to be insignificant, the apparently densest groups, known as compact groups appear so dense when seen in projection onto the plane of the sky that their members often overlap. These groups thus appear as dense as the cores of rich clusters. The most popular catalog of compact groups, compiled by Hickson (1982), includes isolation among its selection critera. Therefore, in comparison with the cores of rich clusters, Hickson's compact groups (HCGs) appear to be the densest isolated regions in the Universe (in galaxies per unit volume), and thus provide in principle a clean laboratory for studying the competition of very strong gravitational interactions. The $64,000 question here is then: Are compact groups really bound systems as dense as they appear? If dense groups indeed exist, then one expects that each of the dynamical processes leading to the interaction of their member galaxies should be greatly enhanced. This leads us to the questions: How stable are dense groups? How do they form? And the related question, fascinating to any theorist: What dynamical processes predominate in dense groups of galaxies? If HCGs are not bound dense systems, but instead 1D change alignments (Mamon 1986, 1987; Walke & Mamon 1989) or 3D transient cores (Rose 1979) within larger looser systems of galaxies, then the relevant question is: How frequent are chance configurations within loose groups? Here, the author answers these last four questions after comparing in some detail the methods used and the results obtained in the different studies of dense groups.

  15. Kinetic chemistry of dense interstellar clouds

    International Nuclear Information System (INIS)

    Graedel, T.E.; Langer, W.D.; Frerking, M.A.

    1982-01-01

    A detailed model of the time-dependent chemistry of dense interstellar clouds has been developed to study the dominant chemical processes in carbon and oxygen isotope fractionation, formation of nitrogen-containing molecules, evolution of product molecules as a function of cloud density and temperature, and other topics of interest. The full computation involves 328 individual reactions (expanded to 1067 to study carbon and oxygen isotope chemistry); photodegradation processes are unimportant in these dense clouds and are excluded

  16. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks.

    Science.gov (United States)

    Lei, Chunyang; Bie, Hongxia; Fang, Gengfa; Zhang, Xuekun

    2015-12-03

    Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT), Machine-to-Machine (M2M) communications, Vehicular-to-Vehicular (V2V) communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  17. An Adaptive Channel Access Method for Dynamic Super Dense Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Chunyang Lei

    2015-12-01

    Full Text Available Super dense and distributed wireless sensor networks have become very popular with the development of small cell technology, Internet of Things (IoT, Machine-to-Machine (M2M communications, Vehicular-to-Vehicular (V2V communications and public safety networks. While densely deployed wireless networks provide one of the most important and sustainable solutions to improve the accuracy of sensing and spectral efficiency, a new channel access scheme needs to be designed to solve the channel congestion problem introduced by the high dynamics of competing nodes accessing the channel simultaneously. In this paper, we firstly analyzed the channel contention problem using a novel normalized channel contention analysis model which provides information on how to tune the contention window according to the state of channel contention. We then proposed an adaptive channel contention window tuning algorithm in which the contention window tuning rate is set dynamically based on the estimated channel contention level. Simulation results show that our proposed adaptive channel access algorithm based on fast contention window tuning can achieve more than 95 % of the theoretical optimal throughput and 0 . 97 of fairness index especially in dynamic and dense networks.

  18. Constitutive law of dense granular matter

    International Nuclear Information System (INIS)

    Hatano, Takahiro

    2010-01-01

    The frictional properties of dense granular matter under steady shear flow are investigated using numerical simulation. Shear flow tends to localize near the driving boundary unless the coefficient of restitution is close to zero and the driving velocity is small. The bulk friction coefficient is independent of shear rate in dense and slow flow, whereas it is an increasing function of shear rate in rapid flow. The coefficient of restitution affects the friction coefficient only in such rapid flow. Contrastingly, in dense and slow regime, the friction coefficient is independent of the coefficient of restitution and mainly determined by the elementary friction coefficient and the rotation of grains. It is found that the mismatch between the vorticity of flow and the angular frequency of grains plays a key role to the frictional properties of sheared granular matter.

  19. Graphene reinforced alumina nano-composites

    Czech Academy of Sciences Publication Activity Database

    Porwal, H.; Tatarko, Peter; Grasso, S.; Khaliq, J.; Dlouhý, Ivo; Reece, M.J.

    2013-01-01

    Roč. 64, NOV (2013), s. 359-369 ISSN 0008-6223 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : fracture toughness determination * ceramic-matrix composites * carbon nanotubes Subject RIV: JI - Composite Materials Impact factor: 6.160, year: 2013

  20. Cirrus Dopant Nano-Composite Coatings

    Science.gov (United States)

    2014-11-01

    coatings without alteration to the existing plating process. Glen Slater, Cirrus Materials | Stephen Flint, Auckland UniServices Ltd Report...ADDRESS(ES) University of Auckland ,Cirrus Materials, Auckland , New Zealand, 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY...JiA/ g THE UNIVERSITY ’-" OF AUCKLAND NEW ZEALAND Te Whare Wanan a o Thmaki Makaurau ~"""’ • ........,." ... Southwest Pacific Basin . p

  1. Nucleon structure and properties of dense matter

    International Nuclear Information System (INIS)

    Kutschera, M.; Pethick, C.J.; Illinois Univ., Urbana, IL

    1988-01-01

    We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n 4/3 , n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)

  2. Fast Solvers for Dense Linear Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kauers, Manuel [Research Institute for Symbolic Computation (RISC), Altenbergerstrasse 69, A4040 Linz (Austria)

    2008-10-15

    It appears that large scale calculations in particle physics often require to solve systems of linear equations with rational number coefficients exactly. If classical Gaussian elimination is applied to a dense system, the time needed to solve such a system grows exponentially in the size of the system. In this tutorial paper, we present a standard technique from computer algebra that avoids this exponential growth: homomorphic images. Using this technique, big dense linear systems can be solved in a much more reasonable time than using Gaussian elimination over the rationals.

  3. Dense high temperature ceramic oxide superconductors

    Science.gov (United States)

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  4. Dense high-temperature plasma transport processes

    International Nuclear Information System (INIS)

    Giniyatova, Sh.G.

    2002-01-01

    In this work the transport processes in dense high-temperature semiclassical plasma are studied on the base of the kinetic equation, where the semiclassical potential was used, in its collision integral. The coefficient of plasma electrical conductivity, viscosity and thermal conductivity were received. There were compared with the other authors' results. The Grad's method was used obtaining of viscosity and thermal coefficients. (author)

  5. The electronic pressure in dense plasmas

    International Nuclear Information System (INIS)

    Pozwolski, A.E.

    1982-01-01

    A thermodynamic calculation of the electronic pressure in a dense plasma is given. Approximations involved by the use of the Debye length are avoided, so the above theory remains valid even if the Debye length is smaller than the interionic distance. (author)

  6. APT: Action localization Proposals from dense Trajectories

    NARCIS (Netherlands)

    van Gemert, J.C.; Jain, M.; Gati, E.; Snoek, C.G.M.; Xie, X.; Jones, M.W.; Tam, G.K.L.

    2015-01-01

    This paper is on action localization in video with the aid of spatio-temporal proposals. To alleviate the computational expensive video segmentation step of existing proposals, we propose bypassing the segmentations completely by generating proposals directly from the dense trajectories used to

  7. Dense Alternating Sign Matrices and Extensions

    Czech Academy of Sciences Publication Activity Database

    Fiedler, Miroslav; Hall, F.J.; Stroev, M.

    2014-01-01

    Roč. 444, 1 March (2014), s. 219-226 ISSN 0024-3795 Institutional support: RVO:67985807 Keywords : alternating sign matrix * dense matrix * totally unimodular matrix * combined matrix * generalized complementary basic matrix Subject RIV: BA - General Mathematics Impact factor: 0.939, year: 2014

  8. Coalescence preference in dense packing of bubbles

    Science.gov (United States)

    Kim, Yeseul; Gim, Bopil; Gim, Bopil; Weon, Byung Mook

    2015-11-01

    Coalescence preference is the tendency that a merged bubble from the contact of two original bubbles (parent) tends to be near to the bigger parent. Here, we show that the coalescence preference can be blocked by densely packing of neighbor bubbles. We use high-speed high-resolution X-ray microscopy to clearly visualize individual coalescence phenomenon which occurs in micro scale seconds and inside dense packing of microbubbles with a local packing fraction of ~40%. Previous theory and experimental evidence predict a power of -5 between the relative coalescence position and the parent size. However, our new observation for coalescence preference in densely packed microbubbles shows a different power of -2. We believe that this result may be important to understand coalescence dynamics in dense packing of soft matter. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST and also was supported by Ministry of Science, ICT and Future Planning (2009-0082580) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry and Education, Science and Technology (NRF-2012R1A6A3A04039257).

  9. Probing dense matter with strange hadrons

    CERN Document Server

    Rafelski, Johann; Rafelski, Johann; Letessier, Jean

    2002-01-01

    Analysis of hadron production experimental data allows to understand the properties of the dense matter fireball produced in relativistic heavy ion collisions. We interpret the analysis results and argue that color deconfined state has been formed at highest CERN-SPS energies and at BNL-RHIC.

  10. Ingenious route for ultraviolet-induced graft polymerization achieved on inorganic particle: Fabricating magnetic poly(acrylic acid) densely grafted nanocomposites for Cu{sup 2+} removal

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Qi, E-mail: roundzking@163.com [School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444 (China); Luo, Wenjun [Faculty of Material and Chemistry, China University of Geosciences, Wuhan, 430074 (China); Zhang, Xing [School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444 (China)

    2017-08-15

    Highlights: • A novel PAA brushes-decorated magnetic adsorbent was prepared successfully. • The preparation approach was simple, rapid, and efficient. • Densely polymer grafting can be achieved on inorganic substrate by the method. • The g-MNPs exhibits an outstanding adsorption performance for Cu{sup 2+}. • The Cu{sup 2+}-saturated adsorbent can be separated and regenerated easily. - Abstract: In this study, ultraviolet (UV)-induced graft technology is improved to be successfully applied on inorganic substrate for fabricating a novel poly(acrylic acid) (PAA) brushes-decorated magnetic nano-composite particles (g-MNPs) as a potential adsorbent toward Cu{sup 2+} ion. The most fascinating features of the resultant g-MNPs are the abundant and highly accessible carboxyl groups present in PAA brushes and the rapid separation from the medium by magnetic field after adsorption. Through the new and high-efficiency surface-initiated polymerization route, the densely PAA brushes was successfully immobilized on the MNPs surface with a high grafting yield of 88.3%. Excitingly, the g-MNPs exhibited an exceptional performance for Cu{sup 2+} adsorption, e.g., ultrahigh adsorption capacity (up to 152.1 mg g{sup −1}), rapid adsorption rate (within 30 min) and low residual concentration (below 1.3 ppm). Full kinetic and isotherm analysis as well as thermodynamic study were also undertaken, the results showed that Cu{sup 2+} adsorption followed Langmuir isotherm and the pseudo-second-order kinetic model, the adsorption rate was controlled by two sequential periods of external and intraparticle diffusion. According to the calculated value of thermodynamic parameters, the Cu{sup 2+} adsorption onto g-MNPs was a spontaneous endothermic process. Furthermore, the excellent reusability of the resultant adsorbent was also confirmed, which can keep above 95% adsorption capacity and desorption rate in 8 consecutive cycles.

  11. Preparation and characterization of dense nanohydroxyapatite/PLLA composites

    International Nuclear Information System (INIS)

    Gay, Sandrine; Arostegui, Saioa; Lemaitre, Jacques

    2009-01-01

    Synthetic bone graft substitutes based on PLLA have been largely studied during the past decade. PLLA/hydroxyapatite composites appear as promising materials for large bone defect healing. In this study dense PLLA/nano-hydroxyapatite composites were prepared by hot pressing. Dense samples were investigated rather than porous scaffolds, in order to shed light on possible correlations between intrinsic mechanical properties and nano-hydroxyapatite concentration. Hydroxyapatite deagglomerated by wet attrition milling, and further dispersed into chloroform was used (median diameter = 80 nm). Particle size distribution measurements and transmission electron microscopy show evidence that particle size and dispersion are maintained throughout the successive steps of composite processing. Mechanical properties were tested (uni-axial and diametral compression tests) as a function of nano-hydroxyapatite content. Increasing concentrations of nano-hydroxyapatite (0, 25 and 50 wt.%) increase the Young's modulus and the mechanical strength of the composite; at the same time, the failure mechanism of the material changes from plastic to brittle. Young's modulus over 6 GPa and uniaxial compressive strength over 100 MPa have been achieved. These values expressed in terms of intrinsic tensile and shear strengths indicate that 50 wt.% nano-hydroxyapatite containing samples develop properties comparable to those of cortical bone. PLLA/nano-hydroxyapatite composites are thus promising candidates to develop bioresorbable porous bone substitutes showing superior mechanical performance

  12. Dense Clustered Multi-Channel Wireless Sensor Cloud

    Directory of Open Access Journals (Sweden)

    Sivaramakrishnan Sivakumar

    2015-08-01

    Full Text Available Dense Wireless Sensor Network Clouds have an inherent issue of latency and packet drops with regards to data collection. Though there is extensive literature that tries to address these issues through either scheduling, channel contention or a combination of the two, the problem still largely exists. In this paper, a Clustered Multi-Channel Scheduling Protocol (CMSP is designed that creates a Voronoi partition of a dense network. Each partition is assigned a channel, and a scheduling scheme is adopted to collect data within the Voronoi partitions. This scheme collects data from the partitions concurrently and then passes it to the base station. CMSP is compared using simulation with other multi-channel protocols like Tree-based Multi-Channel, Multi-Channel MAC and Multi-frequency Media Access Control for wireless sensor networks. Results indicate CMSP has higher throughput and data delivery ratio at a lower power consumption due to network partitioning and hierarchical scheduling that minimizes load on the network.

  13. Structural, dielectric and ferroelectric studies of (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} magnetoelectric nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Khader, S. Abdul, E-mail: khadersku@gmail.com; Sankarappa, T., E-mail: sankarappa@rediffmail.com [Department of Physics, Gulbarga University, Gulbarga-585106, Karnataka (India); Muneeswaran, M.; Giridharan, N. V. [Department of Physics, National Institute of Technology, Tiruchirapalli-620015 (India)

    2016-05-06

    The Particulate nano-composites of ferrite and ferroelectric phases having the general formula (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} (x=15%, 30% and 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO{sub 3} (BT) and highly magneto-strictive magnetic component Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4}(MCZF). The presence of constituent phases of ferrite, ferroelectric and their composites were probed and confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). The variation of dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz at room temperature were carried out using a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric data has been thoroughly analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model. The ferroelectric properties of synthesized magneto-electric nano-composites were measured using P-E loop tracer.

  14. WARM EXTENDED DENSE GAS AT THE HEART OF A COLD COLLAPSING DENSE CORE

    International Nuclear Information System (INIS)

    Shinnaga, Hiroko; Phillips, Thomas G.; Furuya, Ray S.; Kitamura, Yoshimi

    2009-01-01

    In order to investigate when and how the birth of a protostellar core occurs, we made survey observations of four well-studied dense cores in the Taurus molecular cloud using CO transitions in submillimeter bands. We report here the detection of unexpectedly warm (∼30-70 K), extended (radius of ∼2400 AU), dense (a few times 10 5 cm -3 ) gas at the heart of one of the dense cores, L1521F (MC27), within the cold dynamically collapsing components. We argue that the detected warm, extended, dense gas may originate from shock regions caused by collisions between the dynamically collapsing components and outflowing/rotating components within the dense core. We propose a new stage of star formation, 'warm-in-cold core stage (WICCS)', i.e., the cold collapsing envelope encases the warm extended dense gas at the center due to the formation of a protostellar core. WICCS would constitute a missing link in evolution between a cold quiescent starless core and a young protostar in class 0 stage that has a large-scale bipolar outflow.

  15. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2016-12-10

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step-size restriction as the method itself. A general recipe for first-order SSP dense output formulae for SSP methods is given, and second-order dense output formulae for several optimal SSP methods are developed. It is shown that SSP dense output formulae of order three and higher do not exist, and that in any method possessing a second-order SSP dense output, the coefficient matrix A has a zero row.

  16. Dense plasma focus - a literature review

    International Nuclear Information System (INIS)

    Tendys, J.

    1976-01-01

    The dense plasma focus (DPF) is a convenient source of short, intense neutron pulses, and dense, high temperature plasma. This review of the literature on the DPF indicates that its operation is still not understood, and attempts to show where the present data is either inadequate or inconsistent. Because the plasma conditions and neutron and x-ray fluxes vary from shot to shot, it is maintained that, to resolve inconsistencies in the present data, spectra need to be measured with energy and time resolution simultaneously, and cannot be built up from a large number of shots. Time resolutions of the order of 1 nsec for pulse lengths of about 100 nsec make these requirements especially difficult. Some theoretical models are presented for the neutron output and its spectrum, but no self-consistent description of the plasma in the focus region is likely for some time. (author)

  17. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei

    2015-01-01

    -ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation......Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X...

  18. Anomalous properties of hot dense nonequilibrium plasmas

    International Nuclear Information System (INIS)

    Ferrante, G; Zarcone, M; Uryupin, S A

    2005-01-01

    A concise overview of a number of anomalous properties of hot dense nonequilibrium plasmas is given. The possibility of quasistationary megagauss magnetic field generation due to Weibel instability is discussed for plasmas created in atom tunnel ionization. The collisionless absorption and reflection of a test electromagnetic wave normally impinging on the plasma with two-temperature bi-maxwellian electron velocity distribution function are studied. Due to the wave magnetic field influence on the electron kinetics in the skin layer the wave absorption and reflection significantly depend on the degree of the electron temperature anisotropy. The linearly polarized impinging wave during reflection transforms into an elliptically polarized one. The problem of transmission of an ultrashort laser pulse through a layer of dense plasma, formed as a result of ionization of a thin foil, is considered. It is shown that the strong photoelectron distribution anisotropy yields an anomalous penetration of the wave field through the foil

  19. Deterministic dense coding with partially entangled states

    Science.gov (United States)

    Mozes, Shay; Oppenheim, Jonathan; Reznik, Benni

    2005-01-01

    The utilization of a d -level partially entangled state, shared by two parties wishing to communicate classical information without errors over a noiseless quantum channel, is discussed. We analytically construct deterministic dense coding schemes for certain classes of nonmaximally entangled states, and numerically obtain schemes in the general case. We study the dependency of the maximal alphabet size of such schemes on the partially entangled state shared by the two parties. Surprisingly, for d>2 it is possible to have deterministic dense coding with less than one ebit. In this case the number of alphabet letters that can be communicated by a single particle is between d and 2d . In general, we numerically find that the maximal alphabet size is any integer in the range [d,d2] with the possible exception of d2-1 . We also find that states with less entanglement can have a greater deterministic communication capacity than other more entangled states.

  20. PHOTOCHEMICAL HEATING OF DENSE MOLECULAR GAS

    Energy Technology Data Exchange (ETDEWEB)

    Glassgold, A. E. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Najita, J. R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-09-10

    Photochemical heating is analyzed with an emphasis on the heating generated by chemical reactions initiated by the products of photodissociation and photoionization. The immediate products are slowed down by collisions with the ambient gas and then heat the gas. In addition to this direct process, heating is also produced by the subsequent chemical reactions initiated by these products. Some of this chemical heating comes from the kinetic energy of the reaction products and the rest from collisional de-excitation of the product atoms and molecules. In considering dense gas dominated by molecular hydrogen, we find that the chemical heating is sometimes as large, if not much larger than, the direct heating. In very dense gas, the total photochemical heating approaches 10 eV per photodissociation (or photoionization), competitive with other ways of heating molecular gas.

  1. Thermodynamic instabilities in hot and dense nuclear matter

    Directory of Open Access Journals (Sweden)

    Lavagno A.

    2016-01-01

    Full Text Available We study the presence of thermodynamic instabilities in a hot and dense nuclear medium where a nuclear phase transition can take place. Similarly to the low density nuclear liquid-gas phase transition, we show that such a phase transition is characterized by pure hadronic matter with both mechanical instability (fluctuations on the baryon density that by chemical-diffusive instability (fluctuations on the strangeness concentration. The analysis is performed by requiring the global conservation of baryon number and zero net strangeness in the framework of an effective relativistic mean field theory with the inclusion of the Δ(1232-isobars, hyperons and the lightest pseudoscalar and vector meson degrees of freedom. It turns out that in this situation hadronic phases with different values of strangeness content may coexist, altering significantly meson-antimeson ratios.

  2. Adaptive Probabilistic Broadcasting over Dense Wireless Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Victor Gau

    2010-01-01

    Full Text Available We propose an idle probability-based broadcasting method, iPro, which employs an adaptive probabilistic mechanism to improve performance of data broadcasting over dense wireless ad hoc networks. In multisource one-hop broadcast scenarios, the modeling and simulation results of the proposed iPro are shown to significantly outperform the standard IEEE 802.11 under saturated condition. Moreover, the results also show that without estimating the number of competing nodes and changing the contention window size, the performance of the proposed iPro can still approach the theoretical bound. We further apply iPro to multihop broadcasting scenarios, and the experiment results show that within the same elapsed time after the broadcasting, the proposed iPro has significantly higher Packet-Delivery Ratios (PDR than traditional methods.

  3. Dense-plasma research using ballistic compressors

    International Nuclear Information System (INIS)

    Hess, H.

    1986-01-01

    An introduction is given to research on dense (or nonideal) plasmas which can be generated to advantage by ballistic compressors. Some properties of ballistic compressors are discussed especially in comparison with shock tubes. A short review is given on the history of these devices for high-pressure plasma generation. The present state of the art is reported including research on the two ZIE (Central Institute for Electron Physics) ballistic compressors. (author)

  4. Studying dense plasmas with coherent XUV pulses

    International Nuclear Information System (INIS)

    Stabile, H.

    2006-12-01

    The investigation of dense plasma dynamic requires the development of diagnostics able to ensure the measurement of electronic density with micro-metric space resolution and sub-nanosecond, or even subpicosecond, time resolution (indeed this must be at least comparable with the characteristic tune scale of plasma evolution). In contrast with low-density plasmas, dense plasmas cannot be studied using optical probes in the visible domain, the density range accessible being limited to the critical density (N c equals 1.1*10 21 λ -2 (μm) ∼ 10 21 cm -3 for infrared). In addition, light is reflected even at smaller densities if the medium exhibits sharp density gradients. Hence probing of dense plasmas, for instance those produced by laser irradiation of solids, requires using shorter wavelength radiation. Thanks to their physical properties, high order harmonics generated in rare gases are particularly adapted to the study of dense plasmas. Indeed, they can naturally be synchronized with the generating laser and their pulse duration is very short, which makes it possible to use them in pump-probe experiments. Moreover, they exhibit good spatial and temporal coherencies. Two types of diagnostics were developed during this thesis. The first one was used to study the instantaneous creation of hot-solid-density plasma generated by focusing a femtosecond high-contrast laser on an ultra-thin foil (100 nm) in the 10 18 W/cm 2 intensity regime. The use of high order harmonics, providing a probe beam of sufficiently short wavelengths to penetrate such a medium, enables the study of its dynamics on the 100 fs time scale. The second one uses the harmonics beam as probe beam (λ equals 32 nm) within an interferometric device. This diagnostic was designed to ensure a micro-metric spatial resolution and a temporal resolution in the femtosecond range. The first results in presence of plasma created by irradiation of an aluminum target underline the potentialities of this new

  5. Particle identification system based on dense aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Barnyakov, A.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Barnyakov, M.Yu. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Beloborodov, K.I., E-mail: K.I.Beloborodov@inp.nsk.su [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Bobrovnikov, V.S.; Buzykaev, A.R. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Danilyuk, A.F. [Boreskov Institute of Catalysis, 5, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Golubev, V.B. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Gulevich, V.V. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Kononov, S.A.; Kravchenko, E.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); Onuchin, A.P.; Martin, K.A. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, 20, Karl Marx prospect, Novosibirsk, 630092 (Russian Federation); Serednyakov, S.I. [Budker Institute of Nuclear Physics, 11, akademika Lavrentieva prospect, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, 2, Pirogova Street, Novosibirsk 630090 (Russian Federation); and others

    2013-12-21

    A threshold Cherenkov counter based on dense aerogel with refraction index n=1.13 is described. This counter is used for kaon identification at momenta below 1 GeV/c in the SND detector, which takes data at the VEPP-2000 e{sup +}e{sup −} collider. The results of measurements of the counter efficiency using electrons, muons, pions, and kaons produced in e{sup +}e{sup −} annihilation are presented.

  6. Leeuwpan fine coal dense medium plant

    CSIR Research Space (South Africa)

    Lundt, M

    2010-11-01

    Full Text Available Beneficiation 2010, 4–6 May 2010. 671The Journal of The Southern African Institute of Mining and Metallurgy VOLUME 110 NOVEMBER 2010 L Leeuwpan fine coal dense medium plant mixed with magnetite in the launder and enters... with production. Plant equipment operational changes Cyclone spigot changes In an attempt to lower the cut-point density, the spigot on the L 672 NOVEMBER 2010 VOLUME 110 The Journal of The Southern African Institute of Mining and Metallurgy Figure 1...

  7. Collective dynamics in dense fluid mixtures

    International Nuclear Information System (INIS)

    Sinha, S.

    1992-01-01

    This thesis deals with the short wavelength collective dynamics of dense binary fluid mixtures. The analysis shows that at the level of linearized generalized hydrodynamics, the longitudinal modes of the system separates essentially into two parts - one involves the coupling of partial density fluctuations of the two species and the other involves coupling of longitudinal momentum and temperature fluctuations. The authors have shown that the coupling of longitudinal momentum and temperature fluctuations leads to an adequate description of sound propagation in such systems. In particular, they show that structural disorder controls the trapping of sound waves in dense mixtures. The coupling of the partial density fluctuations of the two species leads to a simple description of the partial dynamic structure factors. The results are in agreement with the molecular dynamics simulations of soft sphere mixtures. The partial density fluctuations are the slowest decaying fluctuations on molecular length scales and it turns out that nonlinear coupling of these slow modes leads to important corrections to the long time behavior of the time correlation functions determining the shear viscosity in dense mixtures

  8. Formation and fragmentation of protostellar dense cores

    International Nuclear Information System (INIS)

    Maury, Anaelle

    2009-01-01

    Stars form in molecular clouds, when they collapse and fragment to produce protostellar dense cores. These dense cores are then likely to contract under their own gravity, and form young protostars, that further evolve while accreting their circumstellar mass, until they reach the main sequence. The main goal of this thesis was to study the formation and fragmentation of protostellar dense cores. To do so, two main studies, described in this manuscript, were carried out. First, we studied the formation of protostellar cores by quantifying the impact of protostellar outflows on clustered star formation. We carried out a study of the protostellar outflows powered by the young stellar objects currently formed in the NGc 2264-C proto-cluster, and we show that protostellar outflows seem to play a crucial role as turbulence progenitors in clustered star forming regions, although they seem unlikely to significantly modify the global infall processes at work on clump scales. Second, we investigated the formation of multiple systems by core fragmentation, by using high - resolution observations that allow to probe the multiplicity of young protostars on small scales. Our results suggest that the multiplicity rate of protostars on small scales increase while they evolve, and thus favor dynamical scenarios for the formation of multiple systems. Moreover, our results favor magnetized scenarios of core collapse to explain the small-scale properties of protostars at the earliest stages. (author) [fr

  9. Hybrid-Based Dense Stereo Matching

    Science.gov (United States)

    Chuang, T. Y.; Ting, H. W.; Jaw, J. J.

    2016-06-01

    Stereo matching generating accurate and dense disparity maps is an indispensable technique for 3D exploitation of imagery in the fields of Computer vision and Photogrammetry. Although numerous solutions and advances have been proposed in the literature, occlusions, disparity discontinuities, sparse texture, image distortion, and illumination changes still lead to problematic issues and await better treatment. In this paper, a hybrid-based method based on semi-global matching is presented to tackle the challenges on dense stereo matching. To ease the sensitiveness of SGM cost aggregation towards penalty parameters, a formal way to provide proper penalty estimates is proposed. To this end, the study manipulates a shape-adaptive cross-based matching with an edge constraint to generate an initial disparity map for penalty estimation. Image edges, indicating the potential locations of occlusions as well as disparity discontinuities, are approved by the edge drawing algorithm to ensure the local support regions not to cover significant disparity changes. Besides, an additional penalty parameter 𝑃𝑒 is imposed onto the energy function of SGM cost aggregation to specifically handle edge pixels. Furthermore, the final disparities of edge pixels are found by weighting both values derived from the SGM cost aggregation and the U-SURF matching, providing more reliable estimates at disparity discontinuity areas. Evaluations on Middlebury stereo benchmarks demonstrate satisfactory performance and reveal the potency of the hybrid-based dense stereo matching method.

  10. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.; Loczi, Lajos; Jangabylova, Aliya; Kusmanov, Adil

    2016-01-01

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step

  11. About chiral models of dense matter and its magnetic properties

    International Nuclear Information System (INIS)

    Kutschera, M.

    1990-12-01

    The chiral models of dense nucleon matter are discussed. The quark matter with broken chiral symmetry is described. The magnetic properties of dense matter are presented and conclusions are given. 37 refs. (A.S.)

  12. Evolution of dense spatially modulated electron bunches

    Science.gov (United States)

    Balal, N.; Bratman, V. L.; Friedman, A.

    2018-03-01

    An analytical theory describing the dynamics of relativistic moving 1D electron pulses (layers) with the density modulation affected by a space charge has been revised and generalized for its application to the formation of dense picosecond bunches from linear accelerators with laser-driven photo injectors, and its good agreement with General Particle Tracer simulations has been demonstrated. Evolution of quasi-one-dimensional bunches (disks), for which the derived formulas predict longitudinal expansion, is compared with that for thin and long electron cylinders (threads), for which the excitation of non-linear waves with density spikes was found earlier by Musumeci et al. [Phys. Rev. Lett. 106(18), 184801 (2011)] and Musumeci et al. [Phys. Rev. Spec. Top. -Accel. Beams 16(10), 100701 (2013)]. Both types of bunches can be used for efficiency enhancement of THz sources based on the Doppler frequency up-shifted coherent spontaneous radiation of electrons. Despite the strong Coulomb repulsion, the periodicity of a preliminary modulation in dense 1D layers persists during their expansion in the most interesting case of a relatively small change in particle energy. However, the period of modulation increases and its amplitude decreases in time. In the case of a large change in electron energy, the uniformity of periodicity is broken due to different relativistic changes in longitudinal scales along the bunch: the "period" of modulation decreases and its amplitude increases from the rear to the front boundary. Nevertheless, the use of relatively long electron bunches with a proper preliminary spatial modulation of density can provide a significantly higher power and a narrower spectrum of coherent spontaneous radiation of dense bunches than in the case of initially short single bunches with the same charge.

  13. Electron conductivity model for dense plasmas

    International Nuclear Information System (INIS)

    Lee, Y.T.; More, R.M.

    1984-01-01

    An electron conductivity model for dense plasmas is described which gives a consistent and complete set of transport coefficients including not only electrical conductivity and thermal conductivity, but also thermoelectric power, and Hall, Nernst, Ettinghausen, and Leduc--Righi coefficients. The model is useful for simulating plasma experiments with strong magnetic fields. The coefficients apply over a wide range of plasma temperature and density and are expressed in a computationally simple form. Different formulas are used for the electron relaxation time in plasma, liquid, and solid phases. Comparisons with recent calculations and available experimental measurement show the model gives results which are sufficiently accurate for many practical applications

  14. Dense hydrogen plasma: Comparison between models

    International Nuclear Information System (INIS)

    Clerouin, J.G.; Bernard, S.

    1997-01-01

    Static and dynamical properties of the dense hydrogen plasma (ρ≥2.6gcm -3 , 0.1< T<5eV) in the strongly coupled regime are compared through different numerical approaches. It is shown that simplified density-functional molecular-dynamics simulations (DFMD), without orbitals, such as Thomas-Fermi Dirac or Thomas-Fermi-Dirac-Weiszaecker simulations give similar results to more sophisticated descriptions such as Car-Parrinello (CP), tight binding, or path-integral Monte Carlo, in a wide range of temperatures. At very low temperature, screening effects predicted by DFMD are still less pronounced than CP simulations. copyright 1997 The American Physical Society

  15. Electrical and thermal conductivities in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  16. Dense ceramic membranes for methane conversion

    Energy Technology Data Exchange (ETDEWEB)

    Bouwmeester, Henny J.M. [Laboratory for Inorganic Materials Science, Department of Science and Technology and MESA Research Institute, University of Twente, 7500 AE Enschede (Netherlands)

    2003-07-30

    Dense ceramic membranes made from mixed oxygen-ionic and electronic conducting perovskite-related oxides allow separation of oxygen from an air supply at elevated temperatures (>700C). By combining air separation and catalytic partial oxidation of methane to syngas into a ceramic membrane reactor, this technology is expected to significantly reduce the capital costs of conversion of natural gas to liquid added-value products. The present survey is mainly concerned with the material properties that govern the performance of the mixed-conducting membranes in real operating conditions and highlights significant developments in the field.

  17. The Magpie dense z-pinch project

    International Nuclear Information System (INIS)

    Chittenden, J.; Choi, P.; Mitchell, I.; Dangor, A.E.; Haines, M.G.

    1990-01-01

    The authors present a design study on the Mega Ampere Generator for Plasma Implosion Experiments (MAGPIE), a project currently under construction at Imperial College London, to study radiative collapse of a dense Z-pinch plasma created from a 20 um diameter cryogenic hydrogen fiber. The 2 TW generator is composed of four individual 2.4 MV Marx banks of the HERMES III type design with a maximum stored energy of 336 kJ. They drive four 5 ohm Pulse Forming Lines which are combined into a single 1.25 MA in 150 ns to a 150 nH load

  18. Strange mesons in dense nuclear matter

    International Nuclear Information System (INIS)

    Senger, P.

    2000-10-01

    Experimental data on the production of kaons and antikaons in heavy ion collisions at relativistic energies are reviewed with respect to in-medium effects. The K - /K + ratios measured in nucleus-nucleus collisions are 1-2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of K + mesons indicate a repulsive kaon-nucleon potential. Microscopic transport calculations consistently explain both the yields and the emission patterns of kaons and antikaons when assuming that their properties are modified in dense nuclear matter. The K + production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state. (orig.)

  19. Atomic physics in dense plasmas. Recent advances

    International Nuclear Information System (INIS)

    Leboucher-Dalimier, E.; Angelo, P.; Ceccotti, T.; Derfoul, H.; Poquerusse, A.; Sauvan, P.; Oks, E.

    2000-01-01

    This paper presents observations and simulations of novel density-dependent spectroscopic features in hot and dense plasmas. Both time-integrated and time-resolved results using ultra-high resolutions spectrometers are presented; they are justified within the standard spectral line shape theory or the quasi-molecular alternative treatment. A particular attention is paid to the impact of the spatio-temporal evolution of the plasma on the experimental spectra. Satellite-like features and molecular lines in the cases of Flyβ, Heβ are discussed emphasizing their importance for the density diagnostics when ion-ion correlations are significant. (authors)

  20. Structure of a new dense amorphous ice

    International Nuclear Information System (INIS)

    Finney, J.L.; Bowron, D.T.; Soper, A.K.; Loerting, T.; Mayer, E.; Hallbrucker, A.

    2002-01-01

    The detailed structure of a new dense amorphous ice, VHDA, is determined by isotope substitution neutron diffraction. Its structure is characterized by a doubled occupancy of the stabilizing interstitial location that was found in high density amorphous ice, HDA. As would be expected for a thermally activated unlocking of the stabilizing 'interstitial', the transition from VHDA to LDA (low-density amorphous ice) is very sharp. Although its higher density makes VHDA a better candidate than HDA for a physical manifestation of the second putative liquid phase of water, as for the HDA case, the VHDA to LDA transition also appears to be kinetically controlled

  1. Fabrication of dense panels in lithium fluoride

    International Nuclear Information System (INIS)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-01

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated

  2. Quasi-molecular processes in dense plasmas

    International Nuclear Information System (INIS)

    Younger, S.M.

    1991-01-01

    Quasi-molecular phenomena occur in dense plasmas when the interatomic spacing is comparable to the characteristic wavelength of the electrons. If the electronic states are bound, covalent orbitals arise with different excitation energies, radiative rates, and collisional rates than for isolated ions. For continuum electrons, charge localization near transient clusters of nuclei can influence many scattering and transport processes. We identify several novel consequences of quasi-molecular phenomena in plasmas and give a possible explanation of high energy features associated with helium-like emissions lines observed in recent inertial fusion experiments. 7 refs

  3. Graph Quasicontinuous Functions and Densely Continuous Forms

    Directory of Open Access Journals (Sweden)

    Lubica Hola

    2017-07-01

    Full Text Available Let $X, Y$ be topological spaces. A function $f: X \\to Y$ is said to be graph quasicontinuous if there is a quasicontinuous function $g: X \\to Y$ with the graph of $g$ contained in the closure of the graph of $f$. There is a close relation between the notions of graph quasicontinuous functions and minimal usco maps as well as the notions of graph quasicontinuous functions and densely continuous forms. Every function with values in a compact Hausdorff space is graph quasicontinuous; more generally every locally compact function is graph quasicontinuous.

  4. Neutrino interactions in hot and dense matter

    International Nuclear Information System (INIS)

    Reddy, S.; Prakash, M.; Lattimer, J.M.

    1998-01-01

    We study the charged and neutral current weak interaction rates relevant for the determination of neutrino opacities in dense matter found in supernovae and neutron stars. We establish an efficient formalism for calculating differential cross sections and mean free paths for interacting, asymmetric nuclear matter at arbitrary degeneracy. The formalism is valid for both charged and neutral current reactions. Strong interaction corrections are incorporated through the in-medium single particle energies at the relevant density and temperature. The effects of strong interactions on the weak interaction rates are investigated using both potential and effective field-theoretical models of matter. We investigate the relative importance of charged and neutral currents for different astrophysical situations, and also examine the influence of strangeness-bearing hyperons. Our findings show that the mean free paths are significantly altered by the effects of strong interactions and the multi-component nature of dense matter. The opacities are then discussed in the context of the evolution of the core of a protoneutron star. copyright 1998 The American Physical Society

  5. Predicting diffusivities in dense fluid mixtures

    Directory of Open Access Journals (Sweden)

    C. DARIVA

    1999-09-01

    Full Text Available In this work the Enskog solution of the Boltzmann equation, as corrected by Speedy, together with the Weeks-Chandler-Andersen (WCA perturbation theory of liquids is employed in correlating and predicting self-diffusivities of dense fluids. Afterwards this theory is used to estimate mutual diffusion coefficients of solutes at infinite dilution in sub and supercritical solvents. We have also investigated the behavior of Fick diffusion coefficients in the proximity of a binary vapor-liquid critical point since this subject is of great interest for extraction purposes. The approach presented here, which makes use of a density and temperature dependent hard-sphere diameter, is shown to be excellent for predicting diffusivities in dense pure fluids and fluid mixtures. The calculations involved highly nonideal mixtures as well as systems with high molecular asymmetry. The predicted diffusivities are in good agreement with the experimental data for the pure and binary systems. The methodology proposed here makes only use of pure component information and density of mixtures. The simple algebraic relations are proposed without any binary adjustable parameters and can be readily used for estimating diffusivities in multicomponent mixtures.

  6. Cold dense baryonic matter and compact stars

    International Nuclear Information System (INIS)

    Hyun Kyu Lee; Sang-Jin Sin; Mannque Rho

    2011-01-01

    Probing dense hadronic matter is thus far an uncharted field of physics. Here we give a brief summary of the highlights of what has been so far accomplished and what will be done in the years ahead by the World Class University III Project at Hanyang University in the endeavor to unravel and elucidate the multi-facet of the cold dense baryonic matter existing in the interior of the densest visible stable object in the universe, i.e. neutron stars, strangeness stars and/or quark stars, from a modest and simplified starting point of an effective field theory modeled on the premise of QCD as well as from a gravity dual approach of hQCD. The core of the matter of our research is the possible origin of the ∼ 99% of the proton mass that is to be accounted for and how the 'vacuum' can be tweaked so that the source of the mass generation can be uncovered by measurements made in terrestrial as well as space laboratories. Some of the issues treated in the program concern what can be done - both theoretically and experimentally - in anticipation of what's to come for basic physics research in Korea. (authors)

  7. Collective dynamics in dense Hg vapour

    International Nuclear Information System (INIS)

    Ishikawa, D; Inui, M; Matsuda, K; Tamura, K; Baron, A Q R; Tsutsui, S; Tanaka, Y; Ishikawa, T

    2004-01-01

    The dynamic structure factor, S(Q,ο), of dense Hg vapour has been measured by high resolution inelastic x-ray scattering for densities of 3.0, 2.1 and 1.0 g cm -3 corresponding to 0.52, 0.36 and 0.17 times the critical density, respectively, and for momentum transfers between 2.0 and 48 nm -1 . Analysis of the longitudinal current-current correlation function in the framework of generalized hydrodynamics reveals that the frequencies of the collective excitations increase faster with Q than estimated from the macroscopic speed of sound. The ratios of the frequencies were found to be 1.27 at 3.0 g cm -3 , 1.12 at 2.1 g cm -3 and 1.10 at 1.0 g cm -3 . The sound velocity obtained from the present experiments is well reproduced by a wavenumber dependent adiabatic sound velocity, which means that the collective modes remain in the spectra of dense Hg vapour. (letter to the editor)

  8. Redesigning Triangular Dense Matrix Computations on GPUs

    KAUST Repository

    Charara, Ali

    2016-08-09

    A new implementation of the triangular matrix-matrix multiplication (TRMM) and the triangular solve (TRSM) kernels are described on GPU hardware accelerators. Although part of the Level 3 BLAS family, these highly computationally intensive kernels fail to achieve the percentage of the theoretical peak performance on GPUs that one would expect when running kernels with similar surface-to-volume ratio on hardware accelerators, i.e., the standard matrix-matrix multiplication (GEMM). The authors propose adopting a recursive formulation, which enriches the TRMM and TRSM inner structures with GEMM calls and, therefore, reduces memory traffic while increasing the level of concurrency. The new implementation enables efficient use of the GPU memory hierarchy and mitigates the latency overhead, to run at the speed of the higher cache levels. Performance comparisons show up to eightfold and twofold speedups for large dense matrix sizes, against the existing state-of-the-art TRMM and TRSM implementations from NVIDIA cuBLAS, respectively, across various GPU generations. Once integrated into high-level Cholesky-based dense linear algebra algorithms, the performance impact on the overall applications demonstrates up to fourfold and twofold speedups, against the equivalent native implementations, linked with cuBLAS TRMM and TRSM kernels, respectively. The new TRMM/TRSM kernel implementations are part of the open-source KBLAS software library (http://ecrc.kaust.edu.sa/Pages/Res-kblas.aspx) and are lined up for integration into the NVIDIA cuBLAS library in the upcoming v8.0 release.

  9. Dense gas and star formation in individual Giant Molecular Clouds in M31

    Science.gov (United States)

    Viaene, S.; Forbrich, J.; Fritz, J.

    2018-04-01

    Studies both of entire galaxies and of local Galactic star formation indicate a dependency of a molecular cloud's star formation rate (SFR) on its dense gas mass. In external galaxies, such measurements are derived from HCN(1-0) observations, usually encompassing many Giant Molecular Clouds (GMCs) at once. The Andromeda galaxy (M31) is a unique laboratory to study the relation of the SFR and HCN emission down to GMC scales at solar-like metallicities. In this work, we correlate our composite SFR determinations with archival HCN, HCO+, and CO observations, resulting in a sample of nine reasonably representative GMCs. We find that, at the scale of individual clouds, it is important to take into account both obscured and unobscured star formation to determine the SFR. When correlated against the dense-gas mass from HCN, we find that the SFR is low, in spite of these refinements. We nevertheless retrieve an SFR-dense-gas mass correlation, confirming that these SFR tracers are still meaningful on GMC scales. The correlation improves markedly when we consider the HCN/CO ratio instead of HCN by itself. This nominally indicates a dependency of the SFR on the dense-gas fraction, in contradiction to local studies. However, we hypothesize that this partly reflects the limited dynamic range in dense-gas mass, and partly that the ratio of single-pointing HCN and CO measurements may be less prone to systematics like sidelobes. In this case, the HCN/CO ratio would importantly be a better empirical measure of the dense-gas content itself.

  10. Glaciations and dense interstellar clouds; and reply

    Energy Technology Data Exchange (ETDEWEB)

    McCrea, W H [Sussex Univ., Brighton (UK); Dennison, B; Mansfield, V N

    1976-09-16

    Reference is made to Dennison and Mansfield (Nature 261:32 (1976)) who offered comments on a previous paper by the author (Nature 255:607 (1975)), in which he suggested that a possible cause of an ice age on the Earth was the passage of the solar system through an interstellar matter compression region bordering a spiral arm of the Galaxy. Dennison and Mansfield criticised this suggestion because it led them to expect to find a dense cloud of interstellar matter still very close to the Earth, whereas no such cloud is known. It is stated here that this criticism ignores the structure of the Galaxy, that provided the basis of the suggestion. A reply by Dennison and Mansfield is appended.

  11. Charmonium propagation through a dense medium

    Directory of Open Access Journals (Sweden)

    Kopeliovich B.Z.

    2015-01-01

    Full Text Available Attenuation of a colourless c̄c dipole propagating with a large momentum through a hot medium originates from two sources, Debye screening (melting, and inelastic collisions with surrounding scattering centres (absorption. The former never terminates completely production of a bound charmonium in heavy ion collisions, even at very high temperatures. The latter, is controlled my the magnitude of the dipole cross section, related to the transport coefficient, which is the rate of transverse momentum broadening in the medium. A novel procedure of Lorentz boosting of the Schrödinger equation is developed, which allows to calculate the charmonium survival probability employing the path-integral technique, incorporating both melting and absorption. A novel mechanism of charmonium regeneration in a dense medium is proposed.

  12. Frontiers and challenges in warm dense matter

    CERN Document Server

    Desjarlais, Michael; Redmer, Ronald; Trickey, Samuel

    2014-01-01

    Warm Dense Matter (WDM) occupies a loosely defined region of phase space intermediate between solid, liquid, gas, and plasma, and typically shares characteristics of two or more of these phases. WDM is generally associated with the combination of strongly coupled ions and moderately degenerate electrons, and careful attention to quantum physics and electronic structure is essential. The lack of a small perturbation parameter greatly limits approximate attempts at its accurate description. Since WDM resides at the intersection of solid state and high energy density physics, many high energy density physics (HEDP) experiments pass through this difficult region of phase space. Thus, understanding and modeling WDM is key to the success of experiments on diverse facilities. These include the National Ignition Campaign centered on the National Ignition Facility (NIF), pulsed-power driven experiments on the Z machine, ion-beam-driven WDM experiments on the NDCX-II, and fundamental WDM research at the Linear Coherent...

  13. Intrinsically secure fast reactors with dense cores

    International Nuclear Information System (INIS)

    Slessarev, Igor

    2007-01-01

    Secure safety, resistance to weapons material proliferation and problems of long-lived wastes remain the most important 'painful points' of nuclear power. Many innovative reactor concepts have been developed aimed at a radical enhancement of safety. The promising potential of innovative nuclear reactors allows for shifting accents in current reactor safety 'strategy' to reveal this worth. Such strategy is elaborated focusing on the priority for intrinsically secure safety features as well as on sure protection being provided by the first barrier of defence. Concerning the potential of fast reactors (i.e. sodium cooled, lead-cooled, etc.), there are no doubts that they are able to possess many favourable intrinsically secure safety features and to lay the proper foundation for a new reactor generation. However, some of their neutronic characteristics have to be radically improved. Among intrinsically secure safety properties, the following core parameters are significantly important: reactivity margin values, reactivity feed-back and coolant void effects. Ways of designing intrinsically secure safety features in fast reactors (titled hereafter as Intrinsically Secure Fast Reactors - ISFR) can be found in the frame of current reactor technologies by radical enhancement of core neutron economy and by optimization of core compositions. Simultaneously, respecting resistance to proliferation, by using non-enriched fuel feed as well as a core breeding gain close to zero, are considered as the important features (long-lived waste problems will be considered in a separate paper). This implies using the following reactor design options as well as closed fuel cycles with natural U as the reactor feed: ·Ultra-plate 'dense cores' of the ordinary (monolithic) type with negative total coolant void effects. ·Modular type cores. Multiple dense modules can be embedded in the common reflector for achieving the desired NPP total power. The modules can be used also independently (as

  14. Coherent neutrino interactions in a dense medium

    International Nuclear Information System (INIS)

    Kiers, K.; Weiss, N.

    1997-01-01

    Motivated by the effect of matter on neutrino oscillations (the MSW effect) we study in more detail the propagation of neutrinos in a dense medium. The dispersion relation for massive neutrinos in a medium is known to have a minimum at nonzero momentum p∼G F ρ/√(2). We study in detail the origin and consequences of this dispersion relation for both Dirac and Majorana neutrinos both in a toy model with only neutral currents and a single neutrino flavor and in a realistic open-quotes standard modelclose quotes with two neutrino flavors. We find that for a range of neutrino momenta near the minimum of the dispersion relation, Dirac neutrinos are trapped by their coherent interactions with the medium. This effect does not lead to the trapping of Majorana neutrinos. copyright 1997 The American Physical Society

  15. Equation of state of dense baryonic matter

    International Nuclear Information System (INIS)

    Weber, F.; Weigel, M.K.

    1989-01-01

    In a previous investigation we treated nuclear matter as well as neutron matter at zero and finite temperatures in the frame of different relativistic field theoretical models, but with the restriction to nucleons as the only present baryons. This approach is extended by including a larger fraction of baryons and mesons, necessary for a description of baryon matter under extreme conditions. The equation of state (EOS) is calculated in both the Hartree and Hartree-Fock (HF) approximations for dense nuclear as well as neutron matter. Self-interactions of the σ field up to fourth order have been taken into account. For the treatment of many-baryon matter in the HF approach the parameters of the theory had to be readjusted. A phase transition of both many-baryon systems (neutron as well as nuclear matter) in the high-pressure and high-energy-density region has been found. (author)

  16. Nonlinear extraordinary wave in dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Krasovitskiy, V. B., E-mail: krasovit@mail.ru [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Turikov, V. A. [Russian University of Peoples’ Friendship (Russian Federation)

    2013-10-15

    Conditions for the propagation of a slow extraordinary wave in dense magnetized plasma are found. A solution to the set of relativistic hydrodynamic equations and Maxwell’s equations under the plasma resonance conditions, when the phase velocity of the nonlinear wave is equal to the speed of light, is obtained. The deviation of the wave frequency from the resonance frequency is accompanied by nonlinear longitudinal-transverse oscillations. It is shown that, in this case, the solution to the set of self-consistent equations obtained by averaging the initial equations over the period of high-frequency oscillations has the form of an envelope soliton. The possibility of excitation of a nonlinear wave in plasma by an external electromagnetic pulse is confirmed by numerical simulations.

  17. Statistical mechanics of dense granular media

    International Nuclear Information System (INIS)

    Coniglio, A; Fierro, A; Nicodemi, M; Ciamarra, M Pica; Tarzia, M

    2005-01-01

    We discuss some recent results on the statistical mechanics approach to dense granular media. In particular, by analytical mean field investigation we derive the phase diagram of monodisperse and bidisperse granular assemblies. We show that 'jamming' corresponds to a phase transition from a 'fluid' to a 'glassy' phase, observed when crystallization is avoided. The nature of such a 'glassy' phase turns out to be the same as found in mean field models for glass formers. This gives quantitative evidence for the idea of a unified description of the 'jamming' transition in granular media and thermal systems, such as glasses. We also discuss mixing/segregation transitions in binary mixtures and their connections to phase separation and 'geometric' effects

  18. A constitutive law for dense granular flows.

    Science.gov (United States)

    Jop, Pierre; Forterre, Yoël; Pouliquen, Olivier

    2006-06-08

    A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.

  19. Dense gas dispersion in the atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Morten

    1998-09-01

    Dense gas dispersion is characterized by buoyancy induced gravity currents and reduction of the vertical mixing. Liquefied gas releases from industrial accidents are cold because of the heat of evaporation which determines the density for a given concentration and physical properties. The temperature deficit is moderated by the heat flux from the ground, and this convection is an additional source of turbulence which affects the mixing. A simple model as the soil heat flux is used to estimate the ability of the ground to sustain the heat flux during release. The initial enthalpy, release rate, initial entrainment and momentum are discussed for generic source types and the interaction with obstacles is considered. In the MTH project BA experiments source with and without momentum were applied. The continuously released propane gas passed a two-dimensional removable obstacle perpendicular to the wind direction. Ground-level gas concentrations and vertical profiles of concentration, temperature, wind speed and turbulence were measured in front of and behind the obstacle. Ultrasonic anemometers providing fast velocity and concentration signals were mounted at three levels on the masts. The observed turbulence was influenced by the stability and the initial momentum of the jet releases. Additional information were taken from the `Dessert tortoise` ammonia jet releases, from the `Fladis` experiment with transition from dense to passive dispersion, and from the `Thorney Island` continuous releases of isothermal freon mixtures. The heat flux was found to moderate the negative buoyancy in both the propane and ammonia experiments. The heat flux measurements are compared to an estimate by analogy with surface layer theory. (au) 41 tabs., 146 ills., 189 refs.

  20. The effect of a fictitious peer on young children's choice of familiar v. unfamiliar low- and high-energy-dense foods.

    Science.gov (United States)

    Bevelander, Kirsten E; Anschütz, Doeschka J; Engels, Rutger C M E

    2012-09-28

    The present experimental study was the first to investigate the impact of a remote (non-existent) peer on children's food choice of familiar v. unfamiliar low- and high-energy-dense food products. In a computer task, children (n 316; 50·3 % boys; mean age 7·13 (SD 0·75) years) were asked to choose between pictures of familiar and unfamiliar foods in four different choice blocks using the following pairs: (1) familiar v. unfamiliar low-energy-dense foods (fruits and vegetables), (2) familiar v. unfamiliar high-energy-dense foods (high sugar, salt and/or fat content), (3) familiar low-energy-dense v. unfamiliar high-energy-dense foods and (4) unfamiliar low-energy-dense v. familiar high-energy-dense foods. Participants who were not in the control group were exposed to the food choices (either always the familiar or always the unfamiliar food product) of a same-sex and same-age fictitious peer who was supposedly completing the same task at another school. The present study provided insights into children's choices between (un)familiar low- and high-energy-dense foods in an everyday situation. The findings revealed that the use of fictitious peers increased children's willingness to try unfamiliar foods, although children tended to choose high-energy-dense foods over low-energy-dense foods. Intervention programmes that use peer influence to focus on improving children's choice of healthy foods should take into account children's strong aversion to unfamiliar low-energy-dense foods as well as their general preference for familiar and unfamiliar high-energy-dense foods.

  1. Dense Deposit Disease Mimicking a Renal Small Vessel Vasculitis

    Science.gov (United States)

    Singh, Lavleen; Bhardwaj, Swati; Sinha, Aditi; Bagga, Arvind; Dinda, Amit

    2016-01-01

    Dense deposit disease is caused by fluid-phase dysregulation of the alternative complement pathway and frequently deviates from the classic membranoproliferative pattern of injury on light microscopy. Other patterns of injury described for dense deposit disease include mesangioproliferative, acute proliferative/exudative, and crescentic GN. Regardless of the histologic pattern, C3 glomerulopathy, which includes dense deposit disease and C3 GN, is defined by immunofluorescence intensity of C3c two or more orders of magnitude greater than any other immune reactant (on a 0–3 scale). Ultrastructural appearances distinguish dense deposit disease and C3 GN. Focal and segmental necrotizing glomerular lesions with crescents, mimicking a small vessel vasculitis such as ANCA-associated GN, are a very rare manifestation of dense deposit disease. We describe our experience with this unusual histologic presentation and distinct clinical course of dense deposit disease, discuss the pitfalls in diagnosis, examine differential diagnoses, and review the relevant literature. PMID:26361799

  2. dense sweetpotato varieties to farmers in Uganda

    African Journals Online (AJOL)

    ACSS

    been its starch content (Dominquez, 1992); however ... affected are also the most difficult to reach with the ... (seed) have been generated from 2002 to date. ..... use the wetter lowlands to maintain mostly ... marketing and processing was also.

  3. Breast cancer screening in Korean woman with dense breast tissue

    International Nuclear Information System (INIS)

    Shin, Hee Jung; Ko, Eun Sook; Yi, Ann

    2015-01-01

    Asian women, including Korean, have a relatively higher incidence of dense breast tissue, compared with western women. Dense breast tissue has a lower sensitivity for the detection of breast cancer and a higher relative risk for breast cancer, compared with fatty breast tissue. Thus, there were limitations in the mammographic screening for women with dense breast tissue, and many studies for the supplemental screening methods. This review included appropriate screening methods for Korean women with dense breasts. We also reviewed the application and limitation of supplemental screening methods, including breast ultrasound, digital breast tomosynthesis, and breast magnetic resonance imaging; and furthermore investigated the guidelines, as well as the study results

  4. Breast cancer screening in Korean woman with dense breast tissue

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hee Jung [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of); Ko, Eun Sook [Dept. of Radiology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul (Korea, Republic of); Yi, Ann [Dept. of Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul (Korea, Republic of)

    2015-11-15

    Asian women, including Korean, have a relatively higher incidence of dense breast tissue, compared with western women. Dense breast tissue has a lower sensitivity for the detection of breast cancer and a higher relative risk for breast cancer, compared with fatty breast tissue. Thus, there were limitations in the mammographic screening for women with dense breast tissue, and many studies for the supplemental screening methods. This review included appropriate screening methods for Korean women with dense breasts. We also reviewed the application and limitation of supplemental screening methods, including breast ultrasound, digital breast tomosynthesis, and breast magnetic resonance imaging; and furthermore investigated the guidelines, as well as the study results.

  5. DS Mesons in Asymmetric Hot and Dense Hadronic Matter

    Directory of Open Access Journals (Sweden)

    Divakar Pathak

    2015-01-01

    Full Text Available The in-medium properties of DS mesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiral SU(3 model, to SU(4, in order to study the interactions of the charmed hadrons. In the present work, the DS mesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of the DS+ and DS- mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of the DS mesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting between DS+ and DS- mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM experiment at the future Facility for Antiproton and Ion Research (FAIR, GSI, where matter at high baryonic densities is planned to be produced.

  6. Characterisation of Ferrosilicon Dense Medium Separation Material

    International Nuclear Information System (INIS)

    Waanders, F. B.; Mans, A.

    2003-01-01

    Ferrosilicon is used in the dense medium separation of iron ore at Kumba resources, Sishen, South Africa. Due to high cost and losses that occur during use, maximum recovery by means of magnetic separation is aimed for. The purpose of this project was to determine the characteristics of the unused Fe-Si and then to characterise the changes that occur during storage and use thereof. Scanning electron microscopy was used to determine the composition of each sample, whilst Moessbauer spectroscopy yielded a two-sextet spectrum with hyperfine magnetic field strengths of 20 and 31 T, respectively, for the fresh samples. Additional hematite oxide peaks appeared in the Moessbauer spectra after use of the Fe-Si over a length of time, but this did not result in a dramatic degradation of the medium. No definite changes occurred during correct storage methods. It was, however, found that the biggest loss of Fe-Si was due to the abrasion of the particles, which resulted in the formation of an oxihydroxide froth, during the process.

  7. Improved models of dense anharmonic lattices

    Energy Technology Data Exchange (ETDEWEB)

    Rosenau, P., E-mail: rosenau@post.tau.ac.il; Zilburg, A.

    2017-01-15

    We present two improved quasi-continuous models of dense, strictly anharmonic chains. The direct expansion which includes the leading effect due to lattice dispersion, results in a Boussinesq-type PDE with a compacton as its basic solitary mode. Without increasing its complexity we improve the model by including additional terms in the expanded interparticle potential with the resulting compacton having a milder singularity at its edges. A particular care is applied to the Hertz potential due to its non-analyticity. Since, however, the PDEs of both the basic and the improved model are ill posed, they are unsuitable for a study of chains dynamics. Using the bond length as a state variable we manipulate its dispersion and derive a well posed fourth order PDE. - Highlights: • An improved PDE model of a Newtonian lattice renders compacton solutions. • Compactons are classical solutions of the improved model and hence amenable to standard analysis. • An alternative well posed model enables to study head on interactions of lattices' solitary waves. • Well posed modeling of Hertz potential.

  8. Load Designs For MJ Dense Plasma Foci

    Science.gov (United States)

    Link, A.; Povlius, A.; Anaya, R.; Anderson, M. G.; Angus, J. R.; Cooper, C. M.; Falabella, S.; Goerz, D.; Higginson, D.; Holod, I.; McMahon, M.; Mitrani, J.; Koh, E. S.; Pearson, A.; Podpaly, Y. A.; Prasad, R.; van Lue, D.; Watson, J.; Schmidt, A. E.

    2017-10-01

    Dense plasma focus (DPF) Z-pinches are compact pulse power driven devices with coaxial electrodes. The discharge of DPF consists of three distinct phases: first generation of a plasma sheath, plasma rail gun phase where the sheath is accelerated down the electrodes and finally an implosion phase where the plasma stagnates into a z-pinch geometry. During the z-pinch phase, DPFs can produce MeV ion beams, x-rays and neutrons. Megaampere class DPFs with deuterium fills have demonstrated neutron yields in the 1012 neutrons/shot range with pulse durations of 10-100 ns. Kinetic simulations using the code Chicago are being used to evaluate various load configurations from initial sheath formation to the final z-pinch phase for DPFs with up to 5 MA and 1 MJ coupled to the load. Results will be presented from the preliminary design simulations. LLNL-ABS-734785 This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory (LLNL) under Contract DE-AC52-07NA27344 and with support from the Computing Grand Challenge program at LLNL.

  9. Kinetic Simulations of Dense Plasma Focus Breakdown

    Science.gov (United States)

    Schmidt, A.; Higginson, D. P.; Jiang, S.; Link, A.; Povilus, A.; Sears, J.; Bennett, N.; Rose, D. V.; Welch, D. R.

    2015-11-01

    A dense plasma focus (DPF) device is a type of plasma gun that drives current through a set of coaxial electrodes to assemble gas inside the device and then implode that gas on axis to form a Z-pinch. This implosion drives hydrodynamic and kinetic instabilities that generate strong electric fields, which produces a short intense pulse of x-rays, high-energy (>100 keV) electrons and ions, and (in deuterium gas) neutrons. A strong factor in pinch performance is the initial breakdown and ionization of the gas along the insulator surface separating the two electrodes. The smoothness and isotropy of this ionized sheath are imprinted on the current sheath that travels along the electrodes, thus making it an important portion of the DPF to both understand and optimize. Here we use kinetic simulations in the Particle-in-cell code LSP to model the breakdown. Simulations are initiated with neutral gas and the breakdown modeled self-consistently as driven by a charged capacitor system. We also investigate novel geometries for the insulator and electrodes to attempt to control the electric field profile. The initial ionization fraction of gas is explored computationally to gauge possible advantages of pre-ionization which could be created experimentally via lasers or a glow-discharge. Prepared by LLNL under Contract DE-AC52-07NA27344.

  10. Neutrino ground state in a dense star

    International Nuclear Information System (INIS)

    Kiers, K.; Tytgat, M.H.

    1998-01-01

    It has recently been argued that long range forces due to the exchange of massless neutrinos give rise to a very large self-energy in a dense, finite-ranged, weakly charged medium. Such an effect, if real, would destabilize a neutron star. To address this issue we have studied the related problem of a massless neutrino field in the presence of an external, static electroweak potential of finite range. To be precise, we have computed to one loop the exact vacuum energy for the case of a spherical square well potential of depth α and radius R. For small wells, the vacuum energy is reliably determined by a perturbative expansion in the external potential. For large wells, however, the perturbative expansion breaks down. A manifestation of this breakdown is that the vacuum carries a non-zero neutrino charge. The energy and neutrino charge of the ground state are, to a good approximation for large wells, those of a neutrino condensate with chemical potential μ=α. Our results demonstrate explicitly that long-range forces due to the exchange of massless neutrinos do not threaten the stability of neutron stars. copyright 1998 The American Physical Society

  11. Neutral helium spectral lines in dense plasmas

    International Nuclear Information System (INIS)

    Omar, Banaz; Wierling, August; Roepke, Gerd; Guenter, Sibylle

    2006-01-01

    Shift and broadening of isolated neutral helium lines 7281 A ring (2 1 P-3 1 S), 7065 A ring (2 3 P-3 3 S), 6678 A ring (2 1 P-3 1 D), 5048 A ring (2 1 P-4 1 S), 4922 A ring (2 1 P-4 1 D), and 4713 A ring (2 3 P-4 3 S) in a dense plasma are investigated. Based on a quantum statistical theory, the electronic contributions to the shift and width are considered, using the method of thermodynamic Green functions. Dynamic screening of the electron-atom interaction is included. Compared to the width, the electronic shift is more affected by dynamical screening. This effect increases at high density. A cut-off procedure for strong collisions is used. The contribution of the ions is taken into account in a quasi-static approximation, with both the quadratic Stark effect and the quadrupole interaction included. The results for shift and width agree well with the available experimental and theoretical data

  12. Deterministic dense coding and entanglement entropy

    International Nuclear Information System (INIS)

    Bourdon, P. S.; Gerjuoy, E.; McDonald, J. P.; Williams, H. T.

    2008-01-01

    We present an analytical study of the standard two-party deterministic dense-coding protocol, under which communication of perfectly distinguishable messages takes place via a qudit from a pair of nonmaximally entangled qudits in a pure state |ψ>. Our results include the following: (i) We prove that it is possible for a state |ψ> with lower entanglement entropy to support the sending of a greater number of perfectly distinguishable messages than one with higher entanglement entropy, confirming a result suggested via numerical analysis in Mozes et al. [Phys. Rev. A 71, 012311 (2005)]. (ii) By explicit construction of families of local unitary operators, we verify, for dimensions d=3 and d=4, a conjecture of Mozes et al. about the minimum entanglement entropy that supports the sending of d+j messages, 2≤j≤d-1; moreover, we show that the j=2 and j=d-1 cases of the conjecture are valid in all dimensions. (iii) Given that |ψ> allows the sending of K messages and has √(λ 0 ) as its largest Schmidt coefficient, we show that the inequality λ 0 ≤d/K, established by Wu et al. [Phys. Rev. A 73, 042311 (2006)], must actually take the form λ 0 < d/K if K=d+1, while our constructions of local unitaries show that equality can be realized if K=d+2 or K=2d-1

  13. Thermochemistry of dense hydrous magnesium silicates

    Science.gov (United States)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  14. Borehole stability in densely welded tuffs

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1992-07-01

    The stability of boreholes, or more generally of underground openings (i.e. including shafts, ramps, drifts, tunnels, etc.) at locations where seals or plugs are to be placed is an important consideration in seal design for a repository (Juhlin and Sandstedt, 1989). Borehole instability or borehole breakouts induced by stress redistribution could negate the effectiveness of seals or plugs. Breakout fractures along the wall of repository excavations or exploratory holes could provide a preferential flowpath for groundwater or gaseous radionuclides to bypass the plugs. After plug installation, swelling pressures exerted by a plug could induce radial cracks or could open or widen preexisting cracks in the rock at the bottom of the breakouts where the tangential compressive stresses have been released by the breakout process. The purpose of the work reported here is to determine experimentally the stability of a circular hole in a welded tuff sample subjected to various external boundary loads. Triaxial and biaxial borehole stability tests have been performed on densely welded Apache Leap tuff samples and Topopah Spring tuff samples. The nominal diameter of the test hole is 13.3 or 14.4 mm for triaxial testing, and 25.4 mm for biaxial testing. The borehole axis is parallel to one of the principal stress axes. The boreholes are drilled through the samples prior to applying external boundary loads. The boundary loads are progressively increased until breakouts occur or until the maximum load capacity of the loading system has been reached. 74 refs

  15. Packing frustration in dense confined fluids.

    Science.gov (United States)

    Nygård, Kim; Sarman, Sten; Kjellander, Roland

    2014-09-07

    Packing frustration for confined fluids, i.e., the incompatibility between the preferred packing of the fluid particles and the packing constraints imposed by the confining surfaces, is studied for a dense hard-sphere fluid confined between planar hard surfaces at short separations. The detailed mechanism for the frustration is investigated via an analysis of the anisotropic pair distributions of the confined fluid, as obtained from integral equation theory for inhomogeneous fluids at pair correlation level within the anisotropic Percus-Yevick approximation. By examining the mean forces that arise from interparticle collisions around the periphery of each particle in the slit, we calculate the principal components of the mean force for the density profile--each component being the sum of collisional forces on a particle's hemisphere facing either surface. The variations of these components with the slit width give rise to rather intricate changes in the layer structure between the surfaces, but, as shown in this paper, the basis of these variations can be easily understood qualitatively and often also semi-quantitatively. It is found that the ordering of the fluid is in essence governed locally by the packing constraints at each single solid-fluid interface. A simple superposition of forces due to the presence of each surface gives surprisingly good estimates of the density profiles, but there remain nontrivial confinement effects that cannot be explained by superposition, most notably the magnitude of the excess adsorption of particles in the slit relative to bulk.

  16. Deuterium fractionation in dense interstellar clouds

    International Nuclear Information System (INIS)

    Millar, T.J.; Bennett, A.; Herbst, E.

    1989-01-01

    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized. 60 refs

  17. Deuterium fractionation in dense interstellar clouds

    Science.gov (United States)

    Millar, T. J.; Bennett, A.; Herbst, Eric

    1989-05-01

    The time-dependent gas-phase chemistry of deuterium fractionation in dense interstellar clouds ranging in temperature between 10 and 70 K was investigated using a pseudo-time-dependent model similar to that of Brown and Rice (1986). The present approach, however, considers much more complex species, uses more deuterium fractionation reactions, and includes the use of new branching ratios for dissociative recombinations reactions. Results indicate that, in cold clouds, the major and most global source of deuterium fractionation is H2D(+) and ions derived from it, such as DCO(+) and H2DO(+). In warmer clouds, reactions of CH2D(+), C2HD(+), and associated species lead to significant fractionation even at 70 K, which is the assumed Orion temperature. The deuterium abundance ratios calculated at 10 K are consistent with those observed in TMC-1 for most species. However, a comparison between theory and observatiom for Orion, indicates that, for species in the ambient molecular cloud, the early-time results obtained with the old dissociative recombination branching ratios are superior if a temperature of 70 K is utilized.

  18. Matching Cost Filtering for Dense Stereo Correspondence

    Directory of Open Access Journals (Sweden)

    Yimin Lin

    2013-01-01

    Full Text Available Dense stereo correspondence enabling reconstruction of depth information in a scene is of great importance in the field of computer vision. Recently, some local solutions based on matching cost filtering with an edge-preserving filter have been proved to be capable of achieving more accuracy than global approaches. Unfortunately, the computational complexity of these algorithms is quadratically related to the window size used to aggregate the matching costs. The recent trend has been to pursue higher accuracy with greater efficiency in execution. Therefore, this paper proposes a new cost-aggregation module to compute the matching responses for all the image pixels at a set of sampling points generated by a hierarchical clustering algorithm. The complexity of this implementation is linear both in the number of image pixels and the number of clusters. Experimental results demonstrate that the proposed algorithm outperforms state-of-the-art local methods in terms of both accuracy and speed. Moreover, performance tests indicate that parameters such as the height of the hierarchical binary tree and the spatial and range standard deviations have a significant influence on time consumption and the accuracy of disparity maps.

  19. Mining connected global and local dense subgraphs for bigdata

    Science.gov (United States)

    Wu, Bo; Shen, Haiying

    2016-01-01

    The problem of discovering connected dense subgraphs of natural graphs is important in data analysis. Discovering dense subgraphs that do not contain denser subgraphs or are not contained in denser subgraphs (called significant dense subgraphs) is also critical for wide-ranging applications. In spite of many works on discovering dense subgraphs, there are no algorithms that can guarantee the connectivity of the returned subgraphs or discover significant dense subgraphs. Hence, in this paper, we define two subgraph discovery problems to discover connected and significant dense subgraphs, propose polynomial-time algorithms and theoretically prove their validity. We also propose an algorithm to further improve the time and space efficiency of our basic algorithm for discovering significant dense subgraphs in big data by taking advantage of the unique features of large natural graphs. In the experiments, we use massive natural graphs to evaluate our algorithms in comparison with previous algorithms. The experimental results show the effectiveness of our algorithms for the two problems and their efficiency. This work is also the first that reveals the physical significance of significant dense subgraphs in natural graphs from different domains.

  20. Dense chlorinated solvents and other DNAPLs in groundwater

    DEFF Research Database (Denmark)

    Broholm, K.

    1996-01-01

    Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996......Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996...

  1. Interparticle interaction and transport processes in dense semiclassical plasmas

    International Nuclear Information System (INIS)

    Baimbetov, F.B.; Giniyatova, Sh.G.

    2005-01-01

    On the basis of the density response formalism an expression for the pseudopotential of dense semiclassical plasma, which takes account of quantum-mechanical effects, local field corrections, and electronic screening effects is obtained. The static structure factors taking into account both local fields and quantum-mechanical effects are calculated. An electrical conductivity, thermal conductivity, and viscosity of dense semiclassical plasma are studied

  2. Local Content

    CSIR Research Space (South Africa)

    Gibberd, Jeremy

    2016-10-01

    Full Text Available Local content refers to materials and products made in a country as opposed those that are imported. There is an increasing interest in the concept of local content as a means of supporting local economies and providing jobs (Belderbos & Sleuwaegen...

  3. 16. Hot dense plasma atomic processes

    International Nuclear Information System (INIS)

    Werner, Dappen; Totsuji, H.; Nishii, Y.

    2002-01-01

    This document gathers 13 articles whose common feature is to deal with atomic processes in hot plasmas. Density functional molecular dynamics method is applied to the hydrogen plasma in the domain of liquid metallic hydrogen. The effects of the density gradient are taken into account in both the electronic kinetic energy and the exchange energy and it is shown that they almost cancel with each other, extending the applicability of the Thomas-Fermi-Dirac approximation to the cases where the density gradient is not negligible. Another article reports about space and time resolved M-shell X-ray measurements of a laser-produced gas jet xenon plasma. Plasma parameters have been measured by ion acoustic and electron plasma waves Thomson scattering. Photo-ionization becomes a dominant atomic process when the density and the temperature of plasmas are relatively low and when the plasma is submitted to intense external radiation. It is shown that 2 plasmas which have a very different density but have the same ionization parameters, are found in a similar ionization state. Most radiation hydrodynamics codes use radiative opacity data from available libraries of atomic data. Several articles are focused on the determination of one group Rosseland and Planck mean analytical formulas for several single elements used in inertial fusion targets. In another paper the plasma density effect on population densities, effective ionization, recombination rate coefficients and on emission lines from carbon and Al ions in hot dense plasma, is studied. The last article is devoted to a new atomic model in plasmas that considers the occupation probability of the bound state and free state density in the presence of the plasma micro-field. (A.C.)

  4. DENSE MOLECULAR CORES BEING EXTERNALLY HEATED

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gwanjeong; Lee, Chang Won; Kim, Mi-Ryang [Radio Astronomy division, Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon, 34055 (Korea, Republic of); Gopinathan, Maheswar [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263129 (India); Jeong, Woong-Seob, E-mail: archer81@kasi.re.kr [Department of Astronomy and Space Science, University of Science and Technology, 217 Gajungro, Yuseong-gu, Daejeon, 34113 (Korea, Republic of)

    2016-06-20

    We present results of our study of eight dense cores, previously classified as starless, using infrared (3–160 μ m) imaging observations with the AKARI telescope and molecular line (HCN and N{sub 2}H{sup +}) mapping observations with the KVN telescope. Combining our results with the archival IR to millimeter continuum data, we examined the starless nature of these eight cores. Two of the eight cores are found to harbor faint protostars having luminosities of ∼0.3–4.4 L {sub ⊙}. The other six cores are found to remain starless and probably are in a dynamically transitional state. The temperature maps produced using multi-wavelength images show an enhancement of about 3–6 K toward the outer boundary of these cores, suggesting that they are most likely being heated externally by nearby stars and/or interstellar radiation fields. Large virial parameters and an overdominance of red asymmetric line profiles over the cores may indicate that the cores are set into either an expansion or an oscillatory motion, probably due to the external heating. Most of the starless cores show a coreshine effect due to the scattering of light by the micron-sized dust grains. This may imply that the age of the cores is of the order of ∼10{sup 5} years, which is consistent with the timescale required for the cores to evolve into an oscillatory stage due to external perturbation. Our observational results support the idea that the external feedback from nearby stars and/or interstellar radiation fields may play an important role in the dynamical evolution of the cores.

  5. Multicontextual correlates of energy-dense, nutrient-poor snack food consumption by adolescents.

    Science.gov (United States)

    Larson, Nicole; Miller, Jonathan M; Eisenberg, Marla E; Watts, Allison W; Story, Mary; Neumark-Sztainer, Dianne

    2017-05-01

    Frequent consumption of energy-dense, nutrient-poor snack foods is an eating behavior of public health concern. This study was designed to inform strategies for reducing adolescent intake of energy-dense snack foods by identifying individual and environmental influences. Surveys were completed in 2009-2010 by 2540 adolescents (54% females, mean age = 14.5 ± 2.0, 80% nonwhite) in Minneapolis-St. Paul, Minnesota schools. Daily servings of energy-dense snack food was assessed using a food frequency questionnaire that asked about consumption of 21 common snack food items, such as potato chips, cookies, and candy. Data representing characteristics of adolescents' environments were collected from parents/caregivers, friends, school personnel, Geographic Information System sources, and a content analysis of favorite television shows. Linear regression was used to examine relationships between each individual or environmental characteristic and snack food consumption in separate models and also to examine relationships in a model including all of the characteristics simultaneously. The factors found to be significantly associated with higher energy-dense snack food intake represented individual attitudes/behaviors (e.g., snacking while watching television) and characteristics of home/family (e.g., home unhealthy food availability), peer (friends' energy-dense snack food consumption), and school (e.g., student snack consumption norms) environments. In total, 25.5% of the variance in adolescents' energy-dense snack food consumption was explained when factors from within each context were examined together. The results suggest that the design of interventions targeting improvement in the dietary quality of adolescents' snack food choices should address relevant individual factors (e.g., eating while watching television) along with characteristics of their home/family (e.g., limiting the availability of unhealthy foods), peer (e.g., guiding the efforts of a peer leader in

  6. Fabrication of dense panels in lithium fluoride; Fabrication de panneaux denses en fluorure de lithium

    Energy Technology Data Exchange (ETDEWEB)

    Farcy, P.; Roger, J.; Pointud, R.

    1958-04-15

    The authors report a study aimed at the fabrication of large and dense lithium fluoride panels. This sintered lithium fluoride is then supposed to be used for the construction of barriers of protection against a flow of thermal neutrons. They briefly present the raw material which is used under the form of chamotte obtained through a pre-sintering process which is also described. Grain size measurements and sample preparation are indicated. Shaping, drying, and thermal treatment are briefly described, and characteristics of the sintered product are indicated.

  7. FttC-Based Fronthaul for 5G Dense/Ultra-Dense Access Network: Performance and Costs in Realistic Scenarios

    Directory of Open Access Journals (Sweden)

    Franco Mazzenga

    2017-10-01

    Full Text Available One distinctive feature of the next 5G systems is the presence of a dense/ultra-dense wireless access network with a large number of access points (or nodes at short distances from each other. Dense/ultra-dense access networks allow for providing very high transmission capacity to terminals. However, the deployment of dense/ultra-dense networks is slowed down by the cost of the fiber-based infrastructure required to connect radio nodes to the central processing units and then to the core network. In this paper, we investigate the possibility for existing FttC access networks to provide fronthaul capabilities for dense/ultra-dense 5G wireless networks. The analysis is realistic in that it is carried out considering an actual access network scenario, i.e., the Italian FttC deployment. It is assumed that access nodes are connected to the Cabinets and to the corresponding distributors by a number of copper pairs. Different types of cities grouped in terms of population have been considered. Results focus on fronthaul transport capacity provided by the FttC network and have been expressed in terms of the available fronthaul bit rate per node and of the achievable coverage.

  8. Rates of Thermonuclear Reactions in Dense Plasmas

    International Nuclear Information System (INIS)

    Tsytovich, V.N.; Bornatici, M.

    2000-01-01

    The problem of plasma screening of thermonuclear reactions has attracted considerable scientific interest ever since Salpeter's seminal paper, but it is still faced with controversial statements and without any definite conclusion. It is of relevant importance to thermonuclear reactions in dense astrophysical plasmas, for which charge screening can substantially affect the reaction rates. Whereas Salpeter and a number of subsequent investigations have dealt with static screening, Carraro, Schafer, and Koonin have drawn attention to the fact that plasma screening of thermonuclear reactions is an essentially dynamic effect. In addressing the issue of collective plasma effects on the thermonuclear reaction rates, the first critical overview of most of the work carried out so far is presented and the validity of the test particle approach is assessed. In contrast to previous investigations, we base our description on the kinetic equation for nonequilibrium plasmas, which accounts for the effects on the rates of thermonuclear reactions of both plasma fluctuations and screening and allows one to analyze explicitly the effects of the fluctuations on the reaction rates. Such a kinetic formulation is more general than both Salpeter's approach and the recently developed statistical approaches and makes it possible to obtain a more comprehensive understanding of the problem. A noticeable result of the fluctuation approach is that the static screening, which affects both the interaction and the self-energy of the reacting nuclei, does not affect the reaction rates, in contrast with the results obtained so far. Instead, a reduction of the thermonuclear reaction rates is obtained as a result of the effect of plasma fluctuations related to the free self-energy of the reacting nuclei. A simple physical explanation of the slowing down of the reaction rates is given, and the relation to the dynamically screened test particle approach is discussed. Corrections to the reaction rates

  9. Neutrino reactions in hot and dense matter

    International Nuclear Information System (INIS)

    Lohs, Andreas

    2015-01-01

    In this thesis, neutrino reactions in hot and dense matter are studied. In particular, this work is concerned with neutrino-matter interactions that are relevant for neutrino transport in core-collapse supernovae (CCSNe). The majority of the energy from a CCSN is released in the form of neutrinos. Accurate understanding and computation of these interactions is most relevant to achieve sufficiently reliable predictions for the evolution of CCSNe and other related question such as the production of heavy elements or neutrino oscillations. For this purpose this work follows the combined approach of searching for new important neutrino reactions and improving the computation of those reactions that are already implemented. First we estimate the relevance of charged-current weak interactions that include muon-neutrinos or muons, as well as the role of neutron decay for neutrino transport in CCSNe. All of these reactions were previously neglected in CCSN-simulations. We derive and compute the matrix element and subsequent semi-analytic expressions for transport properties like the inverse mean free path of the new reactions. It is found that these reactions are important for muon neutrinos and low energy electron antineutrinos at very high densities in the protoneutron star surface. Consequently their implementation might lead to several changes in the prediction of CCSNe signatures such as the nucleosynthesis yields. Second we improve the precision in the computation of well known neutrino-nucleon reactions like neutrino absorption on neutrons. We derive semi-analytic expressions for transport properties that use less restrictive approximations while keeping the computational demand constant. Therefore we consider the full relativistic kinematics of all participating particles i.e. allowing for relativistic nucleons and finite lepton masses. Also the weak magnetism terms of the matrix elements are explicitly included to all orders. From our results we suggest that the

  10. Neutrino reactions in hot and dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Lohs, Andreas

    2015-04-13

    In this thesis, neutrino reactions in hot and dense matter are studied. In particular, this work is concerned with neutrino-matter interactions that are relevant for neutrino transport in core-collapse supernovae (CCSNe). The majority of the energy from a CCSN is released in the form of neutrinos. Accurate understanding and computation of these interactions is most relevant to achieve sufficiently reliable predictions for the evolution of CCSNe and other related question such as the production of heavy elements or neutrino oscillations. For this purpose this work follows the combined approach of searching for new important neutrino reactions and improving the computation of those reactions that are already implemented. First we estimate the relevance of charged-current weak interactions that include muon-neutrinos or muons, as well as the role of neutron decay for neutrino transport in CCSNe. All of these reactions were previously neglected in CCSN-simulations. We derive and compute the matrix element and subsequent semi-analytic expressions for transport properties like the inverse mean free path of the new reactions. It is found that these reactions are important for muon neutrinos and low energy electron antineutrinos at very high densities in the protoneutron star surface. Consequently their implementation might lead to several changes in the prediction of CCSNe signatures such as the nucleosynthesis yields. Second we improve the precision in the computation of well known neutrino-nucleon reactions like neutrino absorption on neutrons. We derive semi-analytic expressions for transport properties that use less restrictive approximations while keeping the computational demand constant. Therefore we consider the full relativistic kinematics of all participating particles i.e. allowing for relativistic nucleons and finite lepton masses. Also the weak magnetism terms of the matrix elements are explicitly included to all orders. From our results we suggest that the

  11. Dense-gas dispersion advection-diffusion model

    International Nuclear Information System (INIS)

    Ermak, D.L.

    1992-07-01

    A dense-gas version of the ADPIC particle-in-cell, advection- diffusion model was developed to simulate the atmospheric dispersion of denser-than-air releases. In developing the model, it was assumed that the dense-gas effects could be described in terms of the vertically-averaged thermodynamic properties and the local height of the cloud. The dense-gas effects were treated as a perturbation to the ambient thermodynamic properties (density and temperature), ground level heat flux, turbulence level (diffusivity), and windfield (gravity flow) within the local region of the dense-gas cloud. These perturbations were calculated from conservation of energy and conservation of momentum principles along with the ideal gas law equation of state for a mixture of gases. ADPIC, which is generally run in conjunction with a mass-conserving wind flow model to provide the advection field, contains all the dense-gas modifications within it. This feature provides the versatility of coupling the new dense-gas ADPIC with alternative wind flow models. The new dense-gas ADPIC has been used to simulate the atmospheric dispersion of ground-level, colder-than-ambient, denser-than-air releases and has compared favorably with the results of field-scale experiments

  12. Finding Hierarchical and Overlapping Dense Subgraphs using Nucleus Decompositions

    Energy Technology Data Exchange (ETDEWEB)

    Seshadhri, Comandur [The Ohio State Univ., Columbus, OH (United States); Pinar, Ali [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sariyuce, Ahmet Erdem [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Catalyurek, Umit [The Ohio State Univ., Columbus, OH (United States)

    2014-11-01

    Finding dense substructures in a graph is a fundamental graph mining operation, with applications in bioinformatics, social networks, and visualization to name a few. Yet most standard formulations of this problem (like clique, quasiclique, k-densest subgraph) are NP-hard. Furthermore, the goal is rarely to nd the \\true optimum", but to identify many (if not all) dense substructures, understand their distribution in the graph, and ideally determine a hierarchical structure among them. Current dense subgraph nding algorithms usually optimize some objective, and only nd a few such subgraphs without providing any hierarchy. It is also not clear how to account for overlaps in dense substructures. We de ne the nucleus decomposition of a graph, which represents the graph as a forest of nuclei. Each nucleus is a subgraph where smaller cliques are present in many larger cliques. The forest of nuclei is a hierarchy by containment, where the edge density increases as we proceed towards leaf nuclei. Sibling nuclei can have limited intersections, which allows for discovery of overlapping dense subgraphs. With the right parameters, the nuclear decomposition generalizes the classic notions of k-cores and k-trusses. We give provable e cient algorithms for nuclear decompositions, and empirically evaluate their behavior in a variety of real graphs. The tree of nuclei consistently gives a global, hierarchical snapshot of dense substructures, and outputs dense subgraphs of higher quality than other state-of-theart solutions. Our algorithm can process graphs with tens of millions of edges in less than an hour.

  13. A text zero-watermarking method based on keyword dense interval

    Science.gov (United States)

    Yang, Fan; Zhu, Yuesheng; Jiang, Yifeng; Qing, Yin

    2017-07-01

    Digital watermarking has been recognized as a useful technology for the copyright protection and authentication of digital information. However, rarely did the former methods focus on the key content of digital carrier. The idea based on the protection of key content is more targeted and can be considered in different digital information, including text, image and video. In this paper, we use text as research object and a text zero-watermarking method which uses keyword dense interval (KDI) as the key content is proposed. First, we construct zero-watermarking model by introducing the concept of KDI and giving the method of KDI extraction. Second, we design detection model which includes secondary generation of zero-watermark and the similarity computing method of keyword distribution. Besides, experiments are carried out, and the results show that the proposed method gives better performance than other available methods especially in the attacks of sentence transformation and synonyms substitution.

  14. Mechanical properties of dense to porous alumina/lanthanum hexaaluminate composite ceramics

    International Nuclear Information System (INIS)

    Negahdari, Zahra; Willert-Porada, Monika; Pfeiffer, Carolin

    2010-01-01

    For development of new composite materials based on lanthanum hexaaluminate and alumina ceramics, a better understanding of the microstructure-properties relationship is essential. In this paper, attention was focused on the evaluation of mechanical properties of lanthanum hexaaluminate/alumina particulate composite. It was found out that the lanthanum hexaaluminate content plays a critical role in determination of the microstructure and mechanical properties of the composite ceramics. In situ formation of plate-like lanthanum hexaaluminate in the ceramic matrix was accompanied with formation of pores so that the microstructure shifted from dense to porous. Increasing the lanthanum hexaaluminate content up to a certain value enhanced the fracture toughness, increased the hardness, and increased the elastic modulus of the composite materials. Further increase in the lanthanum hexaaluminate content degraded the hardness as well as the elastic modulus of composite ceramics. The influence of lanthanum hexaaluminate on mechanical properties was described by means of microstructure, porosity, and intrinsic characteristics of lanthanum hexaaluminate.

  15. Dense interstellar cloud chemistry: Basic issues and possible dynamical solution

    International Nuclear Information System (INIS)

    Prasad, S.S.; Heere, K.R.; Tarafdar, S.P.

    1989-01-01

    Standing at crossroad of enthusiasm and frustration, dense intertellar cloud chemistry has a squarely posed fundamental problem: Why do the grains appear to play at best a minor role in the chemistry? Grain surface chemistry creates considerable difficulties when the authors treat dense clouds as static objects and ignore the implications of the processes by which the clouds became dense in the first place. A new generation of models which treat chemical and dynamical evolutions concurrently are therefore presented as possible solution to the current frustrations. The proposed modeling philosophy and agenda could make the next decade quite exciting for interstellar chemistry

  16. Dense time discretization technique for verification of real time systems

    International Nuclear Information System (INIS)

    Makackas, Dalius; Miseviciene, Regina

    2016-01-01

    Verifying the real-time system there are two different models to control the time: discrete and dense time based models. This paper argues a novel verification technique, which calculates discrete time intervals from dense time in order to create all the system states that can be reached from the initial system state. The technique is designed for real-time systems specified by a piece-linear aggregate approach. Key words: real-time system, dense time, verification, model checking, piece-linear aggregate

  17. Photons in dense nuclear matter: Random-phase approximation

    Science.gov (United States)

    Stetina, Stephan; Rrapaj, Ermal; Reddy, Sanjay

    2018-04-01

    We present a comprehensive and pedagogic discussion of the properties of photons in cold and dense nuclear matter based on the resummed one-loop photon self-energy. Correlations among electrons, muons, protons, and neutrons in β equilibrium that arise as a result of electromagnetic and strong interactions are consistently taken into account within the random phase approximation. Screening effects, damping, and collective excitations are systematically studied in a fully relativistic setup. Our study is relevant to the linear response theory of dense nuclear matter, calculations of transport properties of cold dense matter, and investigations of the production and propagation of hypothetical vector bosons such as the dark photons.

  18. Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

    Directory of Open Access Journals (Sweden)

    Mythili Prakasam

    2015-12-01

    Full Text Available In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes.

  19. Densely crosslinked polycarbosiloxanes .2. Thermal and mechanical properties

    NARCIS (Netherlands)

    Flipsen, T.A C; Derks, R.; van der Vegt, H.A.; Stenekes, R.; Pennings, A.J; Hadziioannou, G

    1997-01-01

    The thermal and mechanical properties of two densely crosslinked polycarbosiloxane systems were investigated in relation to the molecular structure. The networks were prepared from functional branched prepolymers and crosslinked via a hydrosilylation curing reaction. The prepolymers having only

  20. Automated Motion Estimation for 2D Cine DENSE MRI

    Science.gov (United States)

    Gilliam, Andrew D.; Epstein, Frederick H.

    2013-01-01

    Cine displacement encoding with stimulated echoes (DENSE) is a magnetic resonance (MR) method that directly encodes tissue displacement into MR phase images. This technique has successfully interrogated many forms of tissue motion, but is most commonly used to evaluate cardiac mechanics. Currently, motion analysis from cine DENSE images requires manually delineated anatomical structures. An automated analysis would improve measurement throughput, simplify data interpretation, and potentially access important physiological information during the MR exam. In this article, we present the first fully automated solution for the estimation of tissue motion and strain from 2D cine DENSE data. Results using both simulated and human cardiac cine DENSE data indicate good agreement between the automated algorithm and the standard semi-manual analysis method. PMID:22575669

  1. Finding dense locations in symbolic indoor tracking data

    DEFF Research Database (Denmark)

    Ahmed, Tanvir; Pedersen, Torben Bach; Lu, Hua

    2017-01-01

    presents two graph-based models for constrained and semi-constrained indoor movement, respectively, and then uses the models to map raw tracking records into mapping records that represent object entry and exit times in particular locations. Subsequently, an efficient indexing structure called Hierarchical...... Dense Location Time Index (HDLT-Index) is proposed for indexing the time intervals of the mapping table, along with index construction, query processing, and pruning techniques. The HDLT-Index supports very efficient aggregate point, interval, and duration queries as well as dense location queries......Finding the dense locations in large indoor spaces is very useful for many applications such as overloaded area detection, security control, crowd management, indoor navigation, and so on. Indoor tracking data can be enormous and are not immediately ready for finding dense locations. This paper...

  2. Dense Medium Machine Processing Method for Palm Kernel/ Shell ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Cracked palm kernel is a mixture of kernels, broken shells, dusts and other impurities. In ... machine processing method using dense medium, a separator, a shell collector and a kernel .... efficiency, ease of maintenance and uniformity of.

  3. Physics of dense matter, neutron stars, and supernova

    International Nuclear Information System (INIS)

    Glendenning, N.K.

    1989-02-01

    Nuclear and astrophysical evidence on the equation of state of dense matter is examined. The role of hyperonization of matter in the development of proto-neutron stars is briefly discussed. 7 refs., 4 figs

  4. Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

    Science.gov (United States)

    Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

    2015-01-01

    In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes. PMID:26703750

  5. Reply to 'Comment on 'Quantum dense key distribution''

    International Nuclear Information System (INIS)

    Degiovanni, I.P.; Berchera, I. Ruo; Castelletto, S.; Rastello, M.L.; Bovino, F.A.; Colla, A.M.; Castagnoli, G.

    2005-01-01

    In this Reply we propose a modified security proof of the quantum dense key distribution protocol, detecting also the eavesdropping attack proposed by Wojcik in his Comment [Wojcik, Phys. Rev. A 71, 016301 (2005)

  6. Dilemmas of Warfare in Densely Populated Civilian Areas

    OpenAIRE

    Moshe Tamir

    2012-01-01

    This essay attempts to present operational perspectives on conducting warfare in densely populated areas. It also distinguishes between three types of combat within this general category, with the goal of shedding light on this complex type of warfare.

  7. Dense medium ore concentrates of Bois-Noirs; Minerais des bois noirs, concentres de milieu dense

    Energy Technology Data Exchange (ETDEWEB)

    Le Bris, J; Leduc, M

    1959-01-20

    The chemical treatment of uranium concentrates of Bois-Noirs ore obtained by heavy medium are discussed. The first part deals with sulfuric acid attack on the concentrate, and the second part with the separation of the solution from residues by filtration. A third part deals with this separation by decantation. The fourth part deals with the carbonation of the pickling solutions obtained. (author) [French] Le present rapport est relatif a l'etude du traitement chimique de concentres uraniferes de minerais des Bois-Noirs obtenus par milieu dense. Une premiere partie est consacree a l'attaque sulfurique des concentres, une deuxieme partie a Ia separation de Ia solution d'attaque des residus par decantation. Une quatrieme partie a la carbonatation des solutions d'attaque obtenues. (auteur)

  8. A high-powered siren for stable acoustic levitation of dense materials in the earth's gravity

    Science.gov (United States)

    Gammel, Paul M.; Croonquist, Arvid P.; Wang, Taylor G.

    1988-01-01

    Levitation of large dense samples (e.g., 1-cm diameter steel balls) has been performed in a 1-g environment. A siren was used to study the effects of reflector geometry and variable-frequency operation in order to attain stable acoustic positioning. The harmonic content and spatial distribution of the acoustic field have been investigated. The best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper reflector while operating at a frequency slightly below resonance.

  9. Stabilized Acoustic Levitation of Dense Materials Using a High-Powered Siren

    Science.gov (United States)

    Gammell, P. M.; Croonquist, A.; Wang, T. G.

    1982-01-01

    Stabilized acoustic levitation and manipulation of dense (e.g., steel) objects of 1 cm diameter, using a high powered siren, was demonstrated in trials that investigated the harmonic content and spatial distribution of the acoustic field, as well as the effect of sample position and reflector geometries on the acoustic field. Although further optimization is possible, the most stable operation achieved is expected to be adequate for most containerless processing applications. Best stability was obtained with an open reflector system, using a flat lower reflector and a slightly concave upper one. Operation slightly below resonance enhances stability as this minimizes the second harmonic, which is suspected of being a particularly destabilizing influence.

  10. Relating quantum discord with the quantum dense coding capacity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin; Qiu, Liang, E-mail: lqiu@cumt.edu.cn; Li, Song; Zhang, Chi [China University of Mining and Technology, School of Sciences (China); Ye, Bin [China University of Mining and Technology, School of Information and Electrical Engineering (China)

    2015-01-15

    We establish the relations between quantum discord and the quantum dense coding capacity in (n + 1)-particle quantum states. A necessary condition for the vanishing discord monogamy score is given. We also find that the loss of quantum dense coding capacity due to decoherence is bounded below by the sum of quantum discord. When these results are restricted to three-particle quantum states, some complementarity relations are obtained.

  11. Rheology of dense suspensions of non colloidal particles

    OpenAIRE

    Guazzelli , Elisabeth

    2017-01-01

    International audience; Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liq...

  12. Rheology of dense suspensions of non colloidal particles

    OpenAIRE

    Guazzelli Élisabeth

    2017-01-01

    Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical co...

  13. Neutrinos and Nucleosynthesis in Hot and Dense Matter

    Energy Technology Data Exchange (ETDEWEB)

    Fuller, George [Univ. of California, San Diego, CA (United States)

    2016-01-14

    The Topical Collaboration for Neutrinos and Nucleosynthesis in Hot and Dense matter brought together researchers from a variety of nuclear science specialties and a number of institutions to address nuclear physics and neutrino physics problems associated with dense matter and the origin of the elements. See attached final technical reports for (1) the UCSD award and (2) a copy of the report for the whole TC

  14. Relating quantum discord with the quantum dense coding capacity

    International Nuclear Information System (INIS)

    Wang, Xin; Qiu, Liang; Li, Song; Zhang, Chi; Ye, Bin

    2015-01-01

    We establish the relations between quantum discord and the quantum dense coding capacity in (n + 1)-particle quantum states. A necessary condition for the vanishing discord monogamy score is given. We also find that the loss of quantum dense coding capacity due to decoherence is bounded below by the sum of quantum discord. When these results are restricted to three-particle quantum states, some complementarity relations are obtained

  15. Interaction of Interstellar Shocks with Dense Obstacles: Formation of ``Bullets''

    Science.gov (United States)

    Gvaramadze, V. V.

    The so-called cumulative effect take place in converging conical shock waves arising behind dense obstacles overtaken by incident interstellar shock. A significant part of energy of converging flow of matter swept-up by a radiative conical shock can be transferred to a dense jet-like ejection (``bullet'') directed along the cone axis. Possible applications of this effect for star-forming regions (e.g., OMC-1) and supernova remnants (e.g., Vela SNR) are discussed.

  16. Advertising Content

    OpenAIRE

    Simon P. Anderson; Régis Renault

    2002-01-01

    Empirical evidence suggests that most advertisements contain little direct informa- tion. Many do not mention prices. We analyze a firm'ss choice of advertising content and the information disclosed to consumers. A firm advertises only product informa- tion, price information, or both; and prefers to convey only limited product information if possible. Extending the "persuasion" game, we show that quality information takes precedence over price information and horizontal product information.T...

  17. Morphological and Optical Characteristics of Chitosan(1-x):Cuox (4 ≤ x ≤ 12) Based Polymer Nano-Composites: Optical Dielectric Loss as an Alternative Method for Tauc's Model.

    Science.gov (United States)

    Aziz, Shujahadeen B

    2017-12-13

    In this work, copper (Cu) nanoparticles with observable surface plasmonic resonance (SPR) peaks were synthesized by an in-situ method. Chitosan host polymer was used as a reduction medium and a capping agent for the Cu nanoparticles. The surface morphology of the samples was investigated through the use of scanning electron micrograph (SEM) technique. Copper nanoparticles appeared as chains and white specks in the SEM images. The strong peaks due to the Cu element observed in the spectrum of energy dispersive analysis of X-rays. For the nanocomposite samples, obvious peaks due to the SPR phenomena were obtained in the Ultraviolet-visible (UV-vis) spectra. The effect of Cu nanoparticles on the host band gap was understood from absorption edges shifting of absorption edges to lower photon energy. The optical dielectric loss parameter obtained from the measurable quantities was used as an alternative method to study the band structure of the samples. Quantum mechanical models drawbacks, in the study of band gap, were explained based on the optical dielectric loss. A clear dispersion region was able to be observed in refractive indices spectra of the composite samples. A linear relationship with a regression value of 0.99 was achieved between the refractive index and volume fractions of CuI content. Cu nanoparticles with various sizes and homogenous dispersions were also determined from transmission electron microscope (TEM) images.

  18. Experimental Studies of the Transport Parameters of Warm Dense Matter

    Energy Technology Data Exchange (ETDEWEB)

    Chouffani, Khalid [Idaho State Univ., Pocatello, ID (United States)

    2014-12-01

    There is a need to establish fundamental properties of matter and energy under extreme physical conditions. Although high energy density physics (HEDP) research spans a wide range of plasma conditions, there is one unifying regime that is of particular importance and complexity: that of warm dense matter, the transitional state between solid state condensed matter and energetic plasmas. Most laboratory experimental conditions, including inertial confinement implosion, fall into this regime. Because all aspects of laboratory-created high-energy-density plasmas transition through the warm dense matter regime, understanding the fundamental properties to determine how matter and energy interact in this regime is an important aspect of major research efforts in HEDP. Improved understanding of warm dense matter would have significant and wide-ranging impact on HEDP science, from helping to explain wire initiation studies on the Sandia Z machine to increasing the predictive power of inertial confinement fusion modeling. The central goal or objective of our proposed research is to experimentally determine the electrical resistivity, temperature, density, and average ionization state of a variety of materials in the warm dense matter regime, without the use of theoretical calculations. Since the lack of an accurate energy of state (EOS) model is primarily due to the lack of experimental data, we propose an experimental study of the transport coefficients of warm dense matter.

  19. Warm dense matter and Thomson scattering at FLASH

    International Nuclear Information System (INIS)

    Faeustlin, Roland Rainer

    2010-05-01

    X-ray free electron lasers are powerful tools to investigate moderately to strongly correlated solid density low temperature plasmas, named warm dense matter. These plasmas are of most interest for astrophysics and laser plasma interaction, particularly inertial confinement fusion. This work utilizes the ultrashort soft x-ray pulse duration and high brilliance of the free electron laser in Hamburg, FLASH, to generate warm dense matter and to study its ultrafast processes. The techniques applied are absorption measurement, emission spectroscopy and Thomson scattering. Radiative hydrodynamics and Thomson scattering simulations are used to investigate the impact of temperature and density gradients in the sample and to fit the experimental data. The measurements result in a comprehensive picture of soft x-ray matter interaction related to warm dense matter and yield insight into ultrafast equilibration and relaxation mechanisms, in particular impact ionization and radiative recombination. (orig.)

  20. Probing warm dense lithium by inelastic X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Saiz, E; Riley, D [School of Mathematics and Physics, Queen' s University of Belfast, Belfast (United Kingdom); Gregori, G [Clarendon Laboratory, University of Oxford, Parks Road, Oxford (United Kingdom); Gregori, G; Clarke, R J; Neely, D; Notley, M M; Spindloe, C [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Didcot, OX (United Kingdom); Gericke, D O; Vorberger, J; Wunsch, K [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, Coventry (United Kingdom); Barbrel, B; Koenig, M [Laboratoire pour l' Utilisation des Laser Intenses, Ecole Polytechnique - Universite Paris-6, 91 - Palaiseau (France); Freeman, R R; Weber, R L; Van Woerkom, L [Department of Physics, The Ohio State University, Columbus, Ohio (United States); Glenzer, S H; Landen, O L; Neumayer, P; Price, D [Lawrence Livermore National Laboratory, Livermore, California (United States); Khattak, F Y [Department of Physics, Kohat University of Science and Technology, Kohat-26000, NWFP (Pakistan); Pelka, A; Roth, M; Schollmeier, M [Institut fur Kernphysik, Technische Universitat Darmstadt (Germany)

    2008-10-15

    One of the grand challenges of contemporary physics is understanding strongly interacting quantum systems comprising such diverse examples as ultracold atoms in traps, electrons in high-temperature superconductors and nuclear matter. Warm dense matter, defined by temperatures of a few electron volts and densities comparable with solids, is a complex state of such interacting matter. Moreover, the study of warm dense matter states has practical applications for controlled thermonuclear fusion, where it is encountered during the implosion phase, and it also represents laboratory analogues of astrophysical environments found in the core of planets and the crusts of old stars. Here we demonstrate how warm dense matter states can be diagnosed and structural properties can be obtained by inelastic X-ray scattering measurements on a compressed lithium sample. Combining experiments and ab initio simulations enables us to determine its microscopic state and to evaluate more approximate theoretical models for the ionic structure. (authors)

  1. Scale-chiral symmetry, ω meson, and dense baryonic matter

    Science.gov (United States)

    Ma, Yong-Liang; Rho, Mannque

    2018-05-01

    It is shown that explicitly broken scale symmetry is essential for dense skyrmion matter in hidden local symmetry theory. Consistency with the vector manifestation fixed point for the hidden local symmetry of the lowest-lying vector mesons and the dilaton limit fixed point for scale symmetry in dense matter is found to require that the anomalous dimension (|γG2| ) of the gluon field strength tensor squared (G2 ) that represents the quantum trace anomaly should be 1.0 ≲|γG2|≲3.5 . The magnitude of |γG2| estimated here will be useful for studying hadron and nuclear physics based on the scale-chiral effective theory. More significantly, that the dilaton limit fixed point can be arrived at with γG2≠0 at some high density signals that scale symmetry can arise in dense medium as an "emergent" symmetry.

  2. Rayleigh-Taylor/gravitational instability in dense magnetoplasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S., E-mail: shahid.ali@ncp.edu.p [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad (Pakistan); IPFN, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Ahmed, Z. [COMSATS Institute of Information Technology, Department of Physics, Wah Campus (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ahmad, I. [COMSATS Institute of Information Technology, Department of Physics, Islamabad Campus (Pakistan)

    2009-08-10

    The Rayleigh-Taylor instability is investigated in a nonuniform dense quantum magnetoplasma. For this purpose, a quantum hydrodynamical model is used for the electrons whereas the ions are assumed to be cold and classical. The dispersion relation for the Rayleigh-Taylor instability becomes modified with the quantum corrections associated with the Fermi pressure law and the quantum Bohm potential force. Numerically, it is found that the quantum speed and density gradient significantly modify the growth rate of RT instability. In a dense quantum magnetoplasma case, the linear growth rate of RT instability becomes significantly higher than its classical value and the modes are found to be highly localized. The present investigation should be useful in the studies of dense astrophysical magnetoplasmas as well as in laser-produced plasmas.

  3. Warm dense matter and Thomson scattering at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Faeustlin, Roland Rainer

    2010-05-15

    X-ray free electron lasers are powerful tools to investigate moderately to strongly correlated solid density low temperature plasmas, named warm dense matter. These plasmas are of most interest for astrophysics and laser plasma interaction, particularly inertial confinement fusion. This work utilizes the ultrashort soft x-ray pulse duration and high brilliance of the free electron laser in Hamburg, FLASH, to generate warm dense matter and to study its ultrafast processes. The techniques applied are absorption measurement, emission spectroscopy and Thomson scattering. Radiative hydrodynamics and Thomson scattering simulations are used to investigate the impact of temperature and density gradients in the sample and to fit the experimental data. The measurements result in a comprehensive picture of soft x-ray matter interaction related to warm dense matter and yield insight into ultrafast equilibration and relaxation mechanisms, in particular impact ionization and radiative recombination. (orig.)

  4. Rayleigh-Taylor/gravitational instability in dense magnetoplasmas

    International Nuclear Information System (INIS)

    Ali, S.; Ahmed, Z.; Mirza, Arshad M.; Ahmad, I.

    2009-01-01

    The Rayleigh-Taylor instability is investigated in a nonuniform dense quantum magnetoplasma. For this purpose, a quantum hydrodynamical model is used for the electrons whereas the ions are assumed to be cold and classical. The dispersion relation for the Rayleigh-Taylor instability becomes modified with the quantum corrections associated with the Fermi pressure law and the quantum Bohm potential force. Numerically, it is found that the quantum speed and density gradient significantly modify the growth rate of RT instability. In a dense quantum magnetoplasma case, the linear growth rate of RT instability becomes significantly higher than its classical value and the modes are found to be highly localized. The present investigation should be useful in the studies of dense astrophysical magnetoplasmas as well as in laser-produced plasmas.

  5. Arbitrary electron acoustic waves in degenerate dense plasmas

    Science.gov (United States)

    Rahman, Ata-ur; Mushtaq, A.; Qamar, A.; Neelam, S.

    2017-05-01

    A theoretical investigation is carried out of the nonlinear dynamics of electron-acoustic waves in a collisionless and unmagnetized plasma whose constituents are non-degenerate cold electrons, ultra-relativistic degenerate electrons, and stationary ions. A dispersion relation is derived for linear EAWs. An energy integral equation involving the Sagdeev potential is derived, and basic properties of the large amplitude solitary structures are investigated in such a degenerate dense plasma. It is shown that only negative large amplitude EA solitary waves can exist in such a plasma system. The present analysis may be important to understand the collective interactions in degenerate dense plasmas, occurring in dense astrophysical environments as well as in laser-solid density plasma interaction experiments.

  6. Eculizumab for dense deposit disease and C3 glomerulonephritis.

    Science.gov (United States)

    Bomback, Andrew S; Smith, Richard J; Barile, Gaetano R; Zhang, Yuzhou; Heher, Eliot C; Herlitz, Leal; Stokes, M Barry; Markowitz, Glen S; D'Agati, Vivette D; Canetta, Pietro A; Radhakrishnan, Jai; Appel, Gerald B

    2012-05-01

    The principle defect in dense deposit disease and C3 glomerulonephritis is hyperactivity of the alternative complement pathway. Eculizumab, a monoclonal antibody that binds to C5 to prevent formation of the membrane attack complex, may prove beneficial. In this open-label, proof of concept efficacy and safety study, six subjects with dense deposit disease or C3 glomerulonephritis were treated with eculizumab every other week for 1 year. All had proteinuria >1 g/d and/or AKI at enrollment. Subjects underwent biopsy before enrollment and repeat biopsy at the 1-year mark. The subjects included three patients with dense deposit disease (including one patient with recurrent dense deposit disease in allograft) and three patients with C3 glomerulonephritis (including two patients with recurrent C3 glomerulonephritis in allograft). Genetic and complement function testing revealed a mutation in CFH and MCP in one subject each, C3 nephritic factor in three subjects, and elevated levels of serum membrane attack complex in three subjects. After 12 months, two subjects showed significantly reduced serum creatinine, one subject achieved marked reduction in proteinuria, and one subject had stable laboratory parameters but histopathologic improvements. Elevated serum membrane attack complex levels normalized on therapy and paralleled improvements in creatinine and proteinuria. Clinical and histopathologic data suggest a response to eculizumab in some but not all subjects with dense deposit disease and C3 glomerulonephritis. Elevation of serum membrane attack complex before treatment may predict response. Additional research is needed to define the subgroup of dense deposit disease/C3 glomerulonephritis patients in whom eculizumab therapy can be considered.

  7. Pion condensation in cold dense matter and neutron stars

    International Nuclear Information System (INIS)

    Haensel, P.; Proszynski, M.

    1982-01-01

    We study possible influence, on the neutron star structure, of a pion condensation occurring in cold dense matter. Several equations of state with pion-condensed phase are considered. The models of neutron stars are calculated and confronted with existing observational data on pulsars. Such a confrontation appears to rule out the models of dense matter with an abnormal self-bound state, and therefore it seems to exclude the possibility of the existence of abnormal superheavy neutron nuclei and abnormal neutron stars with a liquid pion-condensed surface

  8. Matching of dense plasma focus devices with fission reactors

    International Nuclear Information System (INIS)

    Harms, A.A.; Heindler, M.

    1978-01-01

    The potential role of dense plasma focus devices as compact neutron sources for fissile fuel breeding in conjunction with existing fission reactors is considered. It is found that advanced plasma focus devices can be used effectively in conjunction with neutronically efficient fission reactors to constitute ''self-sufficient'' breeders. Correlations among the various parameters such as the power output and conversion ratio of the fission reactor with the neutron yield and capacitor bank energy of the dense plasma focus device are presented and discussed

  9. Kinetic theory of the interdiffusion coefficient in dense plasmas

    International Nuclear Information System (INIS)

    Boercker, D.B.

    1986-08-01

    Naive applications of Spitzer's theory to very dense plasmas can lead to negative diffusion coefficients. The interdiffusion coefficients in Binary Ionic Mixtures (two species of point ions in a uniform neutralizing background) have been calculated recently using molecular dynamics techniques. These calculations can provide useful benchmarks for theoretical evaluations of the diffusion coefficient in dense plasma mixtures. This paper gives a brief description of a kinetic theoretic approximation to the diffusion coefficient which generalizes Spitzer to high density and is in excellent agreement with the computer simulations. 15 refs., 1 fig., 2 tabs

  10. Leaf Potential Productivity at Different Canopy Levels in Densely-planted and Intermediately-thinned Apple Orchards

    Directory of Open Access Journals (Sweden)

    Ying SUN

    2016-07-01

    Full Text Available Most apple orchards in the apple production districts in China were densely planted with vigorous rootstocks during the 1980s. These orchards have suffered micro-environmental deterioration and loss of fruit quality because of the closed canopy. Modification of the densely-planted orchards is a priority in current apple production. Intermediate thinning is a basic technique used to transform densely-planted apple orchards in China. Our goal was to provide theoretical basis for studying the effect of thinning on the efficiency of photosynthetically active radiation (PAR, fruit quality, and yield. We measured leaf area, solar radiation, and leaf air exchange at different tree canopy levels and by fitting relevant photosynthetic models, vertical distribution characteristics of leaf photosynthetic potentials and PAR were analyzed in various levels within canopies in densely-planted and intermediately-thinned orchards. Intermediate thinning significantly improved the radiant environment inside the canopies. PAR distribution within the canopies in the intermediately-thinned orchard was better distributed than in the densely-planted orchards. The invalid space under 30.0% of relative photosynthetically active radiation (PARr was nearly zero in the intermediately-thinned orchard; but minimum PARr was 17.0% and the space under 0.30 of the relative height of the canopy was invalid for photosynthesis in the densely-planted orchard. The leaf photosynthetic efficiency in the intermediately-thinned orchard was improved. Photosynthetic rates (Pn at the middle and bottom levels of the canopy, respectively, were increased by 7.80% and 10.20% in the intermediately-thinned orchard. Leaf development, which influences photosynthetic potential, was closely related to the surrounding micro-environment, especially light. Leaf photosynthetic potentials were correlated with leaf nitrogen content (Nl and specific leaf weight (Ml at various levels of canopies. Compared

  11. Anomalous optical and electronic properties of dense sodium

    International Nuclear Information System (INIS)

    Li Dafang; Liu Hanyu; Wang Baotian; Shi Hongliang; Zhu Shaoping; Yan Jun; Zhang Ping

    2010-01-01

    Based on the density functional theory, we systematically study the optical and electronic properties of the insulating dense sodium phase (Na-hp4) reported recently (Ma et al., 2009). The structure is found optically anisotropic. Through Bader analysis, we conclude that ionicity exists in the structure and becomes stronger with increasing pressure.

  12. Green-function description of dense polymeric systems

    NARCIS (Netherlands)

    Schoot, van der P.P.A.M.

    2000-01-01

    A self-consistent Green-function description of concentrated polymer solutions and dense polymeric melts is presented. The method, which applies to both uniform and nonuniform systems, is used in this work to calculate the static structure factor of a homogeneous fluid of Gaussian model chains.

  13. Planar simplification and texturing of dense point cloud maps

    NARCIS (Netherlands)

    Ma, L.; Whelan, T.; Bondarau, Y.; With, de P.H.N.; McDonald, J.

    2013-01-01

    Dense RGB-D based SLAM techniques and highfidelity LIDAR scanners are examples from an abundant set of systems capable of providing multi-million point datasets. These large datasets quickly become difficult to process and work with due to the sheer volume of data, which typically contains

  14. Incremental and batch planar simplification of dense point cloud maps

    NARCIS (Netherlands)

    Whelan, T.; Ma, L.; Bondarev, E.; With, de P.H.N.; McDonald, J.

    2015-01-01

    Dense RGB-D SLAM techniques and high-fidelity LIDAR scanners are examples from an abundant set of systems capable of providing multi-million point datasets. These datasets quickly become difficult to process due to the sheer volume of data, typically containing significant redundant information,

  15. Influence of Food Packaging on Children's Energy-dense Snack ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Childhood obesity is a major global public health concern. Rates of obese and overweight children have increased in low- and middle-income countries such as Guatemala. This research will study the influence of food packaging on Guatemalan preschool and school-aged children's energy-dense snack (EDS) food ...

  16. Plasma focus - dense Z pinch and their applications

    International Nuclear Information System (INIS)

    Ishii, Shozo

    1986-02-01

    ''Workshop on the possibility of Z-pinch as a intense pulse light source'' in 1983 and ''Research meeting on plasma focus and Z-pinch'' in 1984 were held at Institute of Plasma Physics, Nagoya University under a collaborating research program. Research activities reported at the meetings on plasma focus, dense Z-pinch, and related phenomena are summerized. (author)

  17. Mechanics of dense suspensions in turbulent channel flows

    NARCIS (Netherlands)

    Picano, F.; Costa, P.; Breugem, W.P.; Brandt, L.

    2015-01-01

    Dense suspensions are usually investigated in the laminar limit where inertial effects are insignificant. When the flow rate is high enough, i.e. at high Reynolds number, the flow may become turbulent and the interaction between solid and liquid phases modifies the turbulence we know in single-phase

  18. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    or an estimate there-of is known. Estimated flow fields in weather satellite imagery might also be used on an operational basis as inputs to short-term weather prediction. In this article we describe a method for the estimation of dense flow fields. Local measurements of motion are obtained by analysis...

  19. A comparative study of fast dense stereo vision algorithms

    NARCIS (Netherlands)

    Sunyoto, H.; Mark, W. van der; Gavrila, D.M.

    2004-01-01

    With recent hardware advances, real-time dense stereo vision becomes increasingly feasible for general-purpose processors. This has important benefits for the intelligent vehicles domain, alleviating object segmentation problems when sensing complex, cluttered traffic scenes. In this paper, we

  20. Dense power-law networks and simplicial complexes

    Science.gov (United States)

    Courtney, Owen T.; Bianconi, Ginestra

    2018-05-01

    There is increasing evidence that dense networks occur in on-line social networks, recommendation networks and in the brain. In addition to being dense, these networks are often also scale-free, i.e., their degree distributions follow P (k ) ∝k-γ with γ ∈(1 ,2 ] . Models of growing networks have been successfully employed to produce scale-free networks using preferential attachment, however these models can only produce sparse networks as the numbers of links and nodes being added at each time step is constant. Here we present a modeling framework which produces networks that are both dense and scale-free. The mechanism by which the networks grow in this model is based on the Pitman-Yor process. Variations on the model are able to produce undirected scale-free networks with exponent γ =2 or directed networks with power-law out-degree distribution with tunable exponent γ ∈(1 ,2 ) . We also extend the model to that of directed two-dimensional simplicial complexes. Simplicial complexes are generalization of networks that can encode the many body interactions between the parts of a complex system and as such are becoming increasingly popular to characterize different data sets ranging from social interacting systems to the brain. Our model produces dense directed simplicial complexes with power-law distribution of the generalized out-degrees of the nodes.

  1. Dense and accurate whole-chromosome haplotyping of individual genomes

    NARCIS (Netherlands)

    Porubsky, David; Garg, Shilpa; Sanders, Ashley D.; Korbel, Jan O.; Guryev, Victor; Lansdorp, Peter M.; Marschall, Tobias

    2017-01-01

    The diploid nature of the human genome is neglected in many analyses done today, where a genome is perceived as a set of unphased variants with respect to a reference genome. This lack of haplotype-level analyses can be explained by a lack of methods that can produce dense and accurate

  2. Sparse symmetric preconditioners for dense linear systems in electromagnetism

    NARCIS (Netherlands)

    Carpentieri, Bruno; Duff, Iain S.; Giraud, Luc; Monga Made, M. Magolu

    2004-01-01

    We consider symmetric preconditioning strategies for the iterative solution of dense complex symmetric non-Hermitian systems arising in computational electromagnetics. In particular, we report on the numerical behaviour of the classical incomplete Cholesky factorization as well as some of its recent

  3. Energy eigenvalues of helium-like atoms in dense plasmas

    International Nuclear Information System (INIS)

    Hashino, Tasuke; Nakazaki, Shinobu; Kato, Takako; Kashiwabara, Hiromichi.

    1987-04-01

    Calculations based on a variational method with wave functions including the correlation of electrons are carried out to obtain energy eigenvalues of Schroedinger's equation for helium-like atoms embedded in dense plasmas, taking the Debye-Hueckel approximation. Energy eigenvalues for the 1 1 S, 2 1 S, and 2 3 S states are obtained as a function of Debye screening length. (author)

  4. Formation of fibrous materials from dense caseinate dispersions

    NARCIS (Netherlands)

    Manski, J.M.; Goot, van der A.J.; Boom, R.M.

    2007-01-01

    Application of shear and cross-linking enzyme transglutaminase (Tgase) induced fibrous hierarchical structures in dense (30% w/w) calcium caseinate (Ca-caseinate) dispersions. Using Tgase was essential for the anisotropic structure formation. The fibrous materials showed anisotropy on both micro-

  5. Common intersection points in dense fluids via equations of state

    International Nuclear Information System (INIS)

    Parsafar, G. A.; Noorian, R.

    2001-01-01

    Some new of state which are derived for dense fluids in recent years, namely the linear isotherm regularity, the dense system equation of state, Ihm-Song-Mason equation of state, and a newly derived semi-empirical equation of state have used to investigate the common intersection point of isobaric expansivity (α p ) in dense fluids. We have shown that the accuracy of these equations of state in predicting such a common intersection point is reduced from the new semi-imperial equation of state, dense system equation of state, linear isotherm regularity, to Ihm-Song-Mason equation of state. respectively. Form physical point of view, the van der Waals equation of state is used to investigate such an intersection point. It is shown that the van der Waals repulsion forces and temperature dependency of the effective molecular diameter are important for existence of this common point. Finally, we have shown that the common intersection points of the isotherms of thermal pressure coefficient, the isotherms of heat capacity at constant volume, and the iso chores of internal pressure for a fluid are related to each other. Also, the common intersection points of the reduced bulk modulus and 1/(Tα p ) for isotherms of a fluid both appear at the same density

  6. Estimation of Dense Image Flow Fields in Fluids

    DEFF Research Database (Denmark)

    Larsen, Rasmus; Conradsen, Knut; Ersbøll, Bjarne Kjær

    1998-01-01

    or an estimate there-of is known. Estimated flow fields in weather satellite imagery might also be used on an operational basis as inputs to short-term weather prediction. In this article we describe a method for the estimation of dense flow fields. Local measurements of motion are obtained by analysis...

  7. Gas-particle interactions in dense gas-fluidised beds

    NARCIS (Netherlands)

    Li, J.; Kuipers, J.A.M.

    2003-01-01

    The occurrence of heterogeneous flow structures in gas-particle flows seriously affects gas¿solid contacting and transport processes in dense gas-fluidized beds. A computational study, using a discrete particle method based on Molecular Dynamics techniques, has been carried out to explore the

  8. Multi-scaling of the dense plasma focus

    Science.gov (United States)

    Saw, S. H.; Lee, S.

    2015-03-01

    The dense plasma focus is a copious source of multi-radiations with many potential new applications of special interest such as in advanced SXR lithography, materials synthesizing and testing, medical isotopes and imaging. This paper reviews the series of numerical experiments conducted using the Lee model code to obtain the scaling laws of the multi-radiations.

  9. Interaction of ultrarelativistic electron and proton bunches with dense plasmas

    CERN Document Server

    Rukhadze, A A

    2012-01-01

    Here we discuss the possibility of employment of ultrarelativistic electron and proton bunches for generation of high plasma wakefields in dense plasmas due to the Cherenkov resonance plasma-bunch interaction. We estimate the maximum amplitude of such a wake and minimum system length at which the maximum amplitude can be generated at the given bunch parameters.

  10. Dense Descriptors for Optical Flow Estimation: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Ahmadreza Baghaie

    2017-02-01

    Full Text Available Estimating the displacements of intensity patterns between sequential frames is a very well-studied problem, which is usually referred to as optical flow estimation. The first assumption among many of the methods in the field is the brightness constancy during movements of pixels between frames. This assumption is proven to be not true in general, and therefore, the use of photometric invariant constraints has been studied in the past. One other solution can be sought by use of structural descriptors rather than pixels for estimating the optical flow. Unlike sparse feature detection/description techniques and since the problem of optical flow estimation tries to find a dense flow field, a dense structural representation of individual pixels and their neighbors is computed and then used for matching and optical flow estimation. Here, a comparative study is carried out by extending the framework of SIFT-flow to include more dense descriptors, and comprehensive comparisons are given. Overall, the work can be considered as a baseline for stimulating more interest in the use of dense descriptors for optical flow estimation.

  11. Active and Nonlinear Microrheology of Dense Colloidal Suspensions

    OpenAIRE

    Harrer, Christian Josef

    2013-01-01

    In this work, we have investigated active and nonlinear microrheology of dense colloidal suspensions, i.e., the forced motion of a singled-out tracer particle by an external force, both in the framework of MCT and via event-driven Brownian Dynamics simulations.

  12. Ranks of dense alternating sign matrices and their sign patterns

    Czech Academy of Sciences Publication Activity Database

    Fiedler, Miroslav; Gao, W.; Hall, F.J.; Jing, G.; Li, Z.; Stroev, M.

    2015-01-01

    Roč. 471, April (2015), s. 109-121 ISSN 0024-3795 R&D Projects: GA ČR(CZ) GA14-07880S Institutional support: RVO:67985840 Keywords : alternating sign matrix * dense matrix * sign pattern matrix Subject RIV: BA - General Mathematics Impact factor: 0.965, year: 2015 http://www.sciencedirect.com/science/article/pii/S0024379515000257

  13. Light localization in cold and dense atomic ensemble

    International Nuclear Information System (INIS)

    Sokolov, Igor

    2017-01-01

    We report on results of theoretical analysis of possibilities of light strong (Anderson) localization in a cold atomic ensemble. We predict appearance of localization in dense atomic systems in strong magnetic field. We prove that in absence of the field the light localization is impossible. (paper)

  14. Energy Flow in Dense Off-Equilibrium Plasma

    Science.gov (United States)

    2016-07-15

    brings the electron density and light emission into LTE at the measured spectral temperature while leaving the ions cold. Because of their large mass... measurements of ionization potential lowering and collision times indense plasmas, allowing us to distinguish between competing dense-plasma models...Hydrodynamic analysis of shockwaves generated by sparks yielded similar measurements ina different, more accessible system. Ultra-fast observations

  15. Deterministic dense coding and faithful teleportation with multipartite graph states

    International Nuclear Information System (INIS)

    Huang, C.-Y.; Yu, I-C.; Lin, F.-L.; Hsu, L.-Y.

    2009-01-01

    We propose schemes to perform the deterministic dense coding and faithful teleportation with multipartite graph states. We also find the sufficient and necessary condition of a viable graph state for the proposed schemes. That is, for the associated graph, the reduced adjacency matrix of the Tanner-type subgraph between senders and receivers should be invertible.

  16. Hugoniot measurements of double-shocked precompressed dense xenon plasmas

    Science.gov (United States)

    Zheng, J.; Chen, Q. F.; Gu, Y. J.; Chen, Z. Y.

    2012-12-01

    The current partially ionized plasmas models for xenon show substantial differences since the description of pressure and thermal ionization region becomes a formidable task, prompting the need for an improved understanding of dense xenon plasmas behavior at above 100 GPa. We performed double-shock compression experiments on dense xenon to determine accurately the Hugoniot up to 172 GPa using a time-resolved optical radiation method. The planar strong shock wave was produced using a flyer plate impactor accelerated up to ˜6 km/s with a two-stage light-gas gun. The time-resolved optical radiation histories were acquired by using a multiwavelength channel optical transience radiance pyrometer. Shock velocity was measured and mass velocity was determined by the impedance-matching methods. The experimental equation of state of dense xenon plasmas are compared with the self-consistent fluid variational calculations of dense xenon in the region of partial ionization over a wide range of pressures and temperatures.

  17. OH megamasers: dense gas & the infrared radiation field

    Science.gov (United States)

    Huang, Yong; Zhang, JiangShui; Liu, Wei; Xu, Jie

    2018-06-01

    To investigate possible factors related to OH megamaser formation (OH MM, L_{H2O}>10L_{⊙}), we compiled a large HCN sample from all well-sampled HCN measurements so far in local galaxies and identified with the OH MM, OH kilomasers (L_{H2O}gas and the dense gas, respectively), we found that OH MM galaxies tend to have stronger HCN emission and no obvious difference on CO luminosity exists between OH MM and non-OH MM. This implies that OH MM formation should be related to the dense molecular gas, instead of the low-density molecular gas. It can be also supported by other facts: (1) OH MMs are confirmed to have higher mean molecular gas density and higher dense gas fraction (L_{HCN}/L_{CO}) than non-OH MMs. (2) After taking the distance effect into account, the apparent maser luminosity is still correlated with the HCN luminosity, while no significant correlation can be found at all between the maser luminosity and the CO luminosity. (3) The OH kMs tend to have lower values than those of OH MMs, including the dense gas luminosity and the dense gas fraction. (4) From analysis of known data of another dense gas tracer HCO^+, similar results can also be obtained. However, from our analysis, the infrared radiation field can not be ruled out for the OH MM trigger, which was proposed by previous works on one small sample (Darling in ApJ 669:L9, 2007). On the contrary, the infrared radiation field should play one more important role. The dense gas (good tracers of the star formation) and its surrounding dust are heated by the ultra-violet (UV) radiation generated by the star formation and the heating of the high-density gas raises the emission of the molecules. The infrared radiation field produced by the re-radiation of the heated dust in turn serves for the pumping of the OH MM.

  18. The structure of protostellar dense cores: a millimeter continuum study

    International Nuclear Information System (INIS)

    Motte, Frederique

    1998-01-01

    A comprehensive theoretical scenario explains low-mass star formation and describes the gravitational collapse of an isolated 'ideal' dense core. The major aim of this thesis is to check the standard model predictions on the structure of protostellar dense cores (or envelopes). The earliest stages of star formation remain poorly known because the protostars are still deeply embedded in massive, opaque circumstellar cocoons. On the one hand, sensitive bolometer arrays very recently allow us to measure the millimeter continuum emission arising from dense cores. Such observations are a powerful tool to constrain the density structure of proto-stellar dense cores (on large length scale). In particular, we studied the structure of isolated proto-stellar envelopes in Taurus and protostars in the ρ Ophiuchi cluster. In order to accurately derive their envelope density power law, we simulated the observation of several envelope models. Then we show that most of the Taurus protostars present a density structure consistent with the standard model predictions. In contrast, dense cores in ρ Ophiuchi main cloud are highly fragmented and protostellar envelope have finite size. Moreover fragmentation appears to be essential in determining the final stellar mass of ρ Oph forming stars. In clusters, fragmentation may thus be at the origin of the stellar initial mass function (IMF). On the other hand, our interferometric millimeter continuum observations are tracing (with higher angular resolution) the inner part of protostellar envelopes. Our study show that disks during protostellar stages are not yet massive and thus do not perturb the analysis of envelope density structure. (author) [fr

  19. Yields, photosynthetic efficiencies, and proximate chemical composition of dense cultures of marine microalgae. A subcontract report

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, W.H.; Seibert, D.L.R.; Alden, M.; Eldridge, P.; Neori, A.

    1983-07-01

    The yields, photosynthetic efficiencies, and proximate composition of several microalgae were compared in dense cultures grown at light intensities up to 70% sunlight. Yields ranged from 3.4 to 21.7 g dry weight/m/sup 2/ day. The highest yield was obtained with Phaeodactylum; the lowest in Botryococcus cultures. The same species had the highest and lowest efficiencies of utilization of photosynthetically active radiation. In nitrogen-sufficient cells of all but one species, most of the dry weight consisted of protein. Lipid content of all species was 20 to 29%, and carbohydrate content 11 to 23%. Lipid content increased somewhat in N-deficient Phaeodactylum and Isochrysis cells, but decreased in deficient Monallanthus cells. Because the overall dry weight yield was reduced by deficiency, lipid yields did not increase. However, since the carbohydrate content increased to about 65% in N-deficient Dunaliella and Tetraselmis cells, the carbohydrate yield increased. In Phaeodactylum the optimum light intensity was about 40% of full sunlight. Most experimets with this alga included a CUSO/sub 4/ filter to decrease infrared irradiance. When this filter was removed, the yield increased because more red light in the photosynthetically active spectral range was included. These results should prove useful to workers attempting to maximize yields and efficiencies, but additional studies are needed. 69 references, 27 figures, 18 tables.

  20. Seeing the Forest Through the Trees: The Distribution and Properties of Dense Molecular Gas in the Milky Way Galaxy

    Science.gov (United States)

    Ellsworth-Bowers, Timothy P.

    cloud structures. This distance catalog of 1,802 objects across the Galactic plane represents the first large-scale analysis of clump-scale objects in a variety of Galactic environments. The Galactocentric positions of these objects begin to trace out the spiral structure of the Milky Way, and suggest that dense molecular gas settles nearer the Galactic midplane than tracers of less-dense gas such as CO. Physical properties computed from the DPDFs reveal that BGPS objects trace a continuum of scales within giant molecular clouds, and extend the scaling relationships known as Larson's Laws to lower-mass substructures. The results presented here represent the first step on the road to seeing the molecular content of the Milky Way as a forest rather than individual nearby trees.

  1. Modification of bentonite clay and application on polypropylene nano composites

    International Nuclear Information System (INIS)

    Oliveira, Akidauana D.B.; Rodrigues, Andre W.B.; Agrawal, Pankaj; Araujo, Edcleide M.; Melo, Tomas J.A.

    2009-01-01

    This work consisted on the modification of Brasgel PA clay with ionic surfactant Praepagen WB and its incorporation into polypropylene. The results of infrared and DR-X was showed that the intercalation of surfactant in the clay and the incorporation of organoclay in PP matrix resulted in the formation of an intercalated structure. The impact strength of PP increased with the incorporation of organoclay. (author)

  2. Fast Reacting Nano Composite Energetic Materials: Synthesis and Combustion Characterization

    Science.gov (United States)

    2015-08-24

    nanoenergetic composites finding extensive use in ordnance and industrial applications, because of its high heat of combustion (~32 kJ/g) (S. H. Fischer ...2011. Farley, Cory. "Reactions of Aluminum with Halogen Containing Oxides." Dissertation. Lubbock, TX, May 2013. Gesner, Jeff , Michelle Pantoya, and...characteristics of novel hybrid nanoenergetic formulations." Combustion and Flame 158 (2011): 964- 978. S. H. Fischer , M. C. Grubelich. "Theoretical

  3. Multiphase Nano-Composite Coatings for Achieving Energy Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Nainaparampil, Jose

    2012-03-26

    UES Inc. and ANL teamed in this work to develop novel coating systems for the protection of surfaces from thermal degradation mainly in two applications; Machining and Die casting. These coatings were specifically designed for the purpose by incorporating required material phases and the overall architecture, which led to reduce the energy usage and increase efficiency of the operations. Following the UES/ANL's feasibility work, the coatings were developed utilizing High power impulse magnetron sputtering (HiPMS) and Large area filtered arc deposition (LAFAD) techniques. Toughness, hardness and oxidation resistance: contrasting qualities have been mixed in the right proportion to attain the suitable material characteristic for the cause. Hafnium diboride (HfB2) based materials provided such a system and its properties were tamed to attain the right combination of toughness and hardness by working on the microstructure and architecture of coatings. An effective interfacing material (graded concentrations of topcoat) was also achieved in this work to provide the required adhesion between the substrate and the coating. Combination of an appropriate bond coat and a functional top coat provided the present thermal degradation resistant coating for cutting tools and die-casting applications. Laboratory level performance tests and industrial level application tests by partner companies (Beta Site Testing) were used for the development of these coatings.

  4. Ecoefficiency indicators for development of nano-composites

    DEFF Research Database (Denmark)

    Olsen, Stig Irving; Laurent, Alexis

    nanocomposites (5 wt%-nanofiller) were investigated; PU/CNT (in-situ polymerization), PP/CNT (in-situ polymerization), PU/clay (bulk polymerization), and PP/clay nanocomposites (bulk polymerization). Due to of lack of information, only the material stages (extraction of materials) and the production...

  5. Novel Nano composite Optical Plastics: Dispersion of Titanium in Polyacrylates

    International Nuclear Information System (INIS)

    Suri, G.; Tyagi, M.; Seshadri, G.; Khandal, R.K.; Verma, G.L.

    2010-01-01

    Polyacrylates have become the preferred materials for optical applications replacing the conventionally used glass due to their superior optical clarity. The major disadvantage with polyacrylates is their low (1.40-1.50) refractive index besides their poor impact resistance. The improvements in refractive index as well as mechanical properties can be achieved by way of incorporation of metals or metal compounds in the matrix. A novel methodology for the incorporation of high refractive index metals into low refractive index polymeric materials to improve the refractive index and impact resistance of the latter has been developed. With the in-situ formation of nanoparticles of TiO 2 , the refractive index of polyacrylates improved from 1.45 to 1.53 and the Abbe number increased from 40 to 57. One of the interesting dimension of this study pertains to the possibility of tailor-making of the two key optical properties of materials by way of varying the amount of TiO 2 being formed in-situ. Thermal stability and impact resistance of nano dispersed (4.3% by wt. of Ti) polyacrylates are found to be better than the neat polyacrylates. Moreover, TiO 2 -containing polyacrylate is of light weight. TEM, SEM, and IR analysis confirms the in-situ formation of nanoparticles of TiO 2 . Gamma irradiation has been used as an eco-friendly technique for polymerization. The developed compositions can be cast polymerized into clear and bubble free material for optical applications.

  6. Multifunctional polymer nano-composite based superhydrophobic surface

    Science.gov (United States)

    Maitra, Tanmoy; Asthana, Ashish; Buchel, Robert; Tiwari, Manish K.; Poulikakos, Dimos

    2014-11-01

    Superhydrophobic surfaces become desirable in plethora of applications in engineering fields, automobile industry, construction industries to name a few. Typical fabrication of superhydrophobic surface consists of two steps: first is to create rough morphology on the substrate of interest, followed by coating of low energy molecules. However, typical exception of the above fabrication technique would be direct coating of functional polymer nanocomposites on substrate where superhydrophobicity is needed. Also in this case, the use of different nanoparticles in the polymer matrix can be exploited to impart multi-functional properties to the superhydrophobic coatings. Herein, different carbon nanoparticles like graphene nanoplatelets (GNP), carbon nanotubes (CNT) and carbon black (CB) are used in fluropolymer matrix to prepare superhydrophobic coatings. The multi-functional properties of coatings are enhanced by combining two different carbon fillers in the matrix. The aforementioned superhydrophobic coatings have shown high electrical conductivity and excellent droplet meniscus impalement resistance. Simultaneous superhydrophobic and oleophillic character of the above coating is used to separate mineral oil and water through filtration of their mixture. Swiss National Science Foundation (SNF) Grant 200021_135479.

  7. NanoComposite Polymers for High Resolution Near Infrared Detectors

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop nanocomposite materials with tuned refractive index in the near infra red spectral range as an index-matched immersion lens for high resolution infra-red...

  8. Advanced Nano-Composites for Increased Energy Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-05-01

    This factsheet describes a research project whose goal is to increase energy efficiency and operating lifetime of wear-intensive industrial components and systems by developing and commercializing a family of ceramic-based monolithic composites that have shown remarkable resistance to wear in laboratory tests.

  9. Polypropylene Nano-composites at High Strain Rate Impacts ...

    African Journals Online (AJOL)

    KBHEEMA

    2017-12-25

    Dec 25, 2017 ... ... requires appropriate selection of performance properties of different ... For example, (Shariatpanahi et al., 2009) revealed improvements of 15% and .... What is important to note is that the directional trend of data points to ...

  10. Carbon Nano-Composite Ablative Rocket Nozzles, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The constantly evolving science of nanotechnology keeps coming around to old ideas re-tooled with new technologies. Though much work has been done examining the...

  11. Astrophysical Nuclear Reaction Rates in the Dense Metallic Environments

    Science.gov (United States)

    Kilic, Ali Ihsan

    2017-09-01

    Nuclear reaction rates can be enhanced by many orders of magnitude in dense and relatively cold astrophysical plasmas such as in white dwarfs, brown dwarfs, and giant planets. Similar conditions are also present in supernova explosions where the ignition conditions are vital for cosmological models. White dwarfs are compact objects that have both extremely high interior densities and very strong local magnetic fields. For the first time, a new formula has been developed to explain cross section and reaction rate quantities for light elements that includes not only the nuclear component but also the material dependence, magnetic field, and crystal structure dependency in dense metallic environments. I will present the impact of the developed formula on the cross section and reaction rates for light elements. This could have possible technological applications in energy production using nuclear fusion reactions.

  12. Propagation of monochromatic light in a hot and dense medium

    Energy Technology Data Exchange (ETDEWEB)

    Masood, Samina S. [University of Houston Clear Lake, Department of Physical and Applied Sciences, Houston, TX (United States)

    2017-12-15

    Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe. (orig.)

  13. Dynamic conductivity and partial ionization in dense fluid hydrogen

    Science.gov (United States)

    Zaghoo, Mohamed

    2018-04-01

    A theoretical description for optical conduction experiments in dense fluid hydrogen is presented. Different quantum statistical approaches are used to describe the mechanism of electronic transport in hydrogen's high-temperature dense phase. We show that at the onset of the metallic transition, optical conduction could be described by a strong rise in atomic polarizability, due to increased ionization, whereas in the highly degenerate limit, the Ziman weak scattering model better accounts for the observed saturation of reflectance. The inclusion of effects of partial ionization in the highly degenerate region provides great agreement with experimental results. Hydrogen's fluid metallic state is revealed to be a partially ionized free-electron plasma. Our results provide some of the first theoretical transport models that are experimentally benchmarked, as well as an important guide for future studies.

  14. Projective block Lanczos algorithm for dense, Hermitian eigensystems

    International Nuclear Information System (INIS)

    Webster, F.; Lo, G.C.

    1996-01-01

    Projection operators are used to effect open-quotes deflation by restrictionclose quotes and it is argued that this is an optimal Lanczos algorithm for memory minimization. Algorithmic optimization is constrained to dense, Hermitian eigensystems where a significant number of the extreme eigenvectors must be obtained reliably and completely. The defining constraints are operator algebra without a matrix representation and semi-orthogonalization without storage of Krylov vectors. other semi-orthogonalization strategies for Lanczos algorithms and conjugate gradient techniques are evaluated within these constraints. Large scale, sparse, complex numerical experiments are performed on clusters of magnetic dipoles, a quantum many-body system that is not block-diagonalizable. Plane-wave, density functional theory of beryllium clusters provides examples of dense complex eigensystems. Use of preconditioners and spectral transformations is evaluated in a preprocessor prior to a high accuracy self-consistent field calculation. 25 refs., 3 figs., 5 tabs

  15. Propagation of monochromatic light in a hot and dense medium

    Science.gov (United States)

    Masood, Samina S.

    2017-12-01

    Photons, as quanta of electromagnetic fields, determine the electromagnetic properties of an extremely hot and dense medium. Considering the properties of the photons in the interacting medium of charged particles, we explicitly calculate the electromagnetic properties such as the electric permittivity, magnetic permeability, refractive index and the propagation speed of electromagnetic signals in an extremely hot and dense background. Photons acquire a dynamically generated mass in such a medium. The screening mass of the photon, the Debye shielding length and the plasma frequency are calculated as functions of the statistical parameters of the medium. We study the properties of the propagating particles in astrophysical systems of distinct statistical conditions. The modifications in the properties of the medium lead to the equation of state of the system. We mainly calculate all these parameters for extremely high temperatures of the early universe.

  16. Wave propagation through a dielectric layer containing densely packed fibers

    International Nuclear Information System (INIS)

    Lee, Siu-Chun

    2011-01-01

    This paper presents the theoretical formulation for the propagation of electromagnetic wave through a dielectric layer containing a random dense distribution of fibers. The diameter of the fibers is comparable to the inter-fiber spacing and wavelength of the incident radiation, but is much smaller than the thickness of the layer. Discontinuity of refractive index across the boundaries of the dielectric layer resulted in multiple internal reflection of both the primary source wave and the scattered waves. As a result the incident waves on the fibers consist of the multiply-reflected primary waves, scattered waves from other fibers, and scattered-reflected waves from the boundaries. The effective propagation constant of the dielectric fiber layer was developed by utilizing the Effective field-Quasicrystalline approximation. The influence of the refractive index of the dielectric medium on the radiative properties of a dense fiber layer was examined by means of numerical analyses.

  17. Observations of non-linear plasmon damping in dense plasmas

    Science.gov (United States)

    Witte, B. B. L.; Sperling, P.; French, M.; Recoules, V.; Glenzer, S. H.; Redmer, R.

    2018-05-01

    We present simulations using finite-temperature density-functional-theory molecular-dynamics to calculate dynamic dielectric properties in warm dense aluminum. The comparison between exchange-correlation functionals in the Perdew, Burke, Ernzerhof approximation, Strongly Constrained and Appropriately Normed Semilocal Density Functional, and Heyd, Scuseria, Ernzerhof (HSE) approximation indicates evident differences in the electron transition energies, dc conductivity, and Lorenz number. The HSE calculations show excellent agreement with x-ray scattering data [Witte et al., Phys. Rev. Lett. 118, 225001 (2017)] as well as dc conductivity and absorption measurements. These findings demonstrate non-Drude behavior of the dynamic conductivity above the Cooper minimum that needs to be taken into account to determine optical properties in the warm dense matter regime.

  18. Pulsar-irradiated stars in dense globular clusters

    Science.gov (United States)

    Tavani, Marco

    1992-01-01

    We discuss the properties of stars irradiated by millisecond pulsars in 'hard' binaries of dense globular clusters. Irradiation by a relativistic pulsar wind as in the case of the eclipsing millisecond pulsar PSR 1957+20 alter both the magnitude and color of the companion star. Some of the blue stragglers (BSs) recently discovered in dense globular clusters can be irradiated stars in binaries containing powerful millisecond pulsars. The discovery of pulsar-driven orbital modulations of BS brightness and color with periods of a few hours together with evidence for radio and/or gamma-ray emission from BS binaries would valuably contribute to the understanding of the evolution of collapsed stars in globular clusters. Pulsar-driven optical modulation of cluster stars might be the only observable effect of a new class of binary pulsars, i.e., hidden millisecond pulsars enshrouded in the evaporated material lifted off from the irradiated companion star.

  19. Temperature Measurements of Dense Plasmas by Detailed Balance

    International Nuclear Information System (INIS)

    Holl, A; Redmer, R; Ropke, G; Reinholz, H; Thiele, R; Fortmann, C; Forster, E; Cao, L; Tschentscher, T; Toleikis, S; Glenzer, S H

    2006-01-01

    Plasmas at high electron densities of n e = 10 20 - 10 26 cm -3 and moderate temperatures T e = 1 - 20 eV are important for laboratory astrophysics, high energy density science and inertial confinement fusion. These plasmas are usually referred to as Warm Dense Matter (WDM) and are characterized by a coupling parameter of Λ ∼> 1 where correlations become important. The characterization of such plasmas is still a challenging task due to the lack of direct measurement techniques for temperatures and densities. They propose to measure the Thomson scattering spectrum of vacuum-UV radiation off density fluctuations in the plasma. Collective Thomson scattering provides accurate data for the electron temperature applying first principles. Further, this method takes advantage of the spectral asymmetry resulting from detailed balance and is independent of collisional effects in these dense systems

  20. Fabrication of dense yttrium oxyfluoride ceramics by hot pressing and their mechanical, thermal, and electrical properties

    Science.gov (United States)

    Tahara, Ryuki; Tsunoura, Toru; Yoshida, Katsumi; Yano, Toyohiko; Kishi, Yukio

    2018-06-01

    Excellent corrosion-resistant materials have been strongly required to reduce particle contamination during the plasma process in semiconductor production. Yttrium oxyfluoride can be a candidate as highly corrosion-resistant material. In this study, three types of dense yttrium oxyfluoride ceramics with different oxygen contents, namely, YOF, Y5O4F7 and Y5O4F7 + YF3, were fabricated by hot pressing, and their mechanical, thermal, and electrical properties were evaluated. Y5O4F7 ceramics showed an excellent thermal stability up to 800 °C, a low loss factor, and volume resistivity comparable to conventional plasma-resistant oxides, such as Y2O3. From these results, yttrium oxyfluoride ceramics are strongly suggested to be used as electrostatic chucks in semiconductor production.

  1. The EOS and neutrino interactions in dense matter

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, M; Reddy, S [Dept. of Physics and Astronomy, SUNY at Stony Brook, Stony Brook, NY (United States)

    1998-06-01

    The deleptonization and cooling times of a newly born neutron star depend on the equation of state (EOS) and neutrino opacities in dense matter. Through model calculations we show that effects of Pauli blocking and many-body correlations due to strong interactions reduce both the neutral and charged current neutrino cross sections by large factors compared to the case in which these effects are ignored. (orig.)

  2. Efficient and Invariant Convolutional Neural Networks for Dense Prediction

    OpenAIRE

    Gao, Hongyang; Ji, Shuiwang

    2017-01-01

    Convolutional neural networks have shown great success on feature extraction from raw input data such as images. Although convolutional neural networks are invariant to translations on the inputs, they are not invariant to other transformations, including rotation and flip. Recent attempts have been made to incorporate more invariance in image recognition applications, but they are not applicable to dense prediction tasks, such as image segmentation. In this paper, we propose a set of methods...

  3. Nucleation of strange matter in dense stellar cores

    International Nuclear Information System (INIS)

    Horvath, J.E.; Benvenuto, O.G.; Vucetich, H.

    1992-01-01

    We investigate the nucleation of strange quark matter inside hot, dense nuclear matter. Applying Zel'dovich's kinetic theory of nucleation we find a lower limit of the temperature T for strange-matter bubbles to appear, which happens to be satisfied inside the Kelvin-Helmholtz cooling era of a compact star life but not much after it. Our bounds thus suggest that a prompt conversion could be achieved, giving support to earlier expectations for nonstandard type-II supernova scenarios

  4. New look at radiative association in dense interstellar clouds

    International Nuclear Information System (INIS)

    Herbst, E.

    1980-01-01

    A corrected statistical theory of radiative association reactions is presented and discussed. Calculations are undertaken to determine the rate coefficients of a variety of radiative association reactions of possible importance in dense interstellar clouds. Our results confirm the suggestion of Smith and Adams that certain radiative association reactions occur quite rapidly at low temperature and are probably important in the synthesis of complex interstellar molecules

  5. Stark broadening in hot, dense laser-produced plasmas

    International Nuclear Information System (INIS)

    Tighe, R.J.; Hooper, C.F. Jr.

    1976-01-01

    Broadened Lyman-α x-ray lines from neon X and argon XVIII radiators, which are immersed in a hot, dense deuterium or deuterium-tritium plasma, are discussed. In particular, these lines are analyzed for several temperature-density cases, characteristic of laser-produced plasmas; special attention paid to the relative importance of ion, electron, and Doppler effects. Static ion microfield distribution functions are tabulated

  6. Proton Radiography for the Diagnostics of a Dense Plasma

    Science.gov (United States)

    Barminova, H. Y.

    2017-12-01

    The possibility of using high-energy proton radiography for dense plasma diagnostics is discussed. The designed telescopic ion optical system for a proton radiography installation with a 1 GeV beam is presented. The schematic diagram of the proton microscope is given. It is shown that the estimate of spatial resolution for the installation obtained with consideration of chromatic aberrations of magnetic quadrupole lenses is limited from below.

  7. Studies of RF Breakdown of Metals in Dense Gases

    CERN Document Server

    Hanlet, Pierrick M; Ankenbrandt, Charles; Johnson, Rolland P; Kaplan, Daniel; Kuchnir, Moyses; Moretti, Alfred; Paul, Kevin; Popovic, Milorad; Yarba, Victor; Yonehara, Katsuya

    2005-01-01

    A study of RF breakdown of metals in gases has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 800 MHz test cell has been used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, chromium, and beryllium electrodes as functions of hydrogen and helium gas density. These results are compared to the predicted or known RF breakdown behavior of these metals in vacuum.

  8. Vortex structures in dense electron-positron-ion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Haque, Q [Theoretical Plasma Physics Division, PINSTECH, P O Nilore, Islamabad (Pakistan)], E-mail: qamar_haque@hotmail.com

    2009-11-15

    A linear dispersion relation for electrostatic quantum drift and acoustic waves has been found for dense electron-positron-ion magnetoplasmas. Both the fermion and thermal temperature effects have been considered for electrons and positrons. In the nonlinear regime, a stationary solution in the form of dipolar vortices has been obtained. For illustration, the results were applied to the astrophysical plasma of the atmosphere of neutron stars/pulsars.

  9. Pulsars and cosmic rays in the dense supernova shells

    International Nuclear Information System (INIS)

    Berezinsky, V.S.; Prilutsky, O.F.

    1977-01-01

    Cosmic rays (c.r.) injected by a young pulsar in the dense supernova shell are considered. The maintenance of the Galactic c.r. pool by pulsar production is shown to have a difficulty: adiabatic energy losses of c.r. in the expanding shell demand a high initial c.r. luminosity of pulsar, which results in too high flux of γ-radiation produced through π 0 -decays (in excess over diffuse γ-ray background). (author)

  10. Non-dense domain operator matrices and Cauchy problems

    International Nuclear Information System (INIS)

    Lalaoui Rhali, S.

    2002-12-01

    In this work, we study Cauchy problems with non-dense domain operator matrices. By assuming that the entries of an unbounded operator matrix are Hille-Yosida operators, we give a necessary and sufficient condition ensuring that the part of this operator matrix generates a semigroup in the closure of its domain. This allows us to prove the well-posedness of the corresponding Cauchy problem. Our results are applied to delay and neutral differential equations. (author)

  11. Memory-efficient analysis of dense functional connectomes

    Directory of Open Access Journals (Sweden)

    Kristian Loewe

    2016-11-01

    Full Text Available The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software are compared with regard to their computational efficiency in terms of memory requirements and computation time. The matrix implementation based on on-demand computations has very low memory requirements thus enabling

  12. Memory-Efficient Analysis of Dense Functional Connectomes.

    Science.gov (United States)

    Loewe, Kristian; Donohue, Sarah E; Schoenfeld, Mircea A; Kruse, Rudolf; Borgelt, Christian

    2016-01-01

    The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software) are compared with regard to their computational efficiency. The matrix implementation based on on-demand computations has very low memory requirements, thus enabling analyses that would be otherwise infeasible to conduct due to

  13. Single-shot optical conductivity measurement of dense aluminum plasmas

    International Nuclear Information System (INIS)

    Churina, I. V.; Cho, B.-I.; Bernstein, A.; Stoker, D. S.; Dalton, A.; Symes, D. R.; Ditmire, T.

    2009-01-01

    The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.

  14. Magnetic fields and dense chromospheres in dMe stars

    International Nuclear Information System (INIS)

    Mullan, D.J.

    1975-01-01

    We examine in a semi-quantitative fashion the hypothesis that dense chromospheres of dMe stars are heated by dissipation of hydromagnetic waves. We propose that dMe stars are a set of magnetic stars on the lower main sequence, with strong fields presumably generated by dynamo action in deep convective envelopes. We discuss how the combination of magnetic fields and dense chromospheres in dMe stars provides a consistent interpretation of the following features: 1) The dMe stars which are most likely to be flares stars are those with hydrogen lines in emission. However, it is proposed that in certain conditions, Balmer lines may appear in absorption, and we suggest that 'negative flares' can be explained at least in part by the occurrence of strong absorption in Hα. 2) The propagation of flare-initiated coronal waves can trigger sympathetic stellar flares. 3) Apart from flare activity, emission line strengths in dMe stars must exhibit time variations due to the emergence of new magnetic flux ropes through the stellar surface. 4) The combination of strong magnetic fields with dense chromospheres makes the Faraday rotation measure large enough to have potentially a detectable effect on polarized visible light. 5) It is suggested that grain formation occurs in starspots on dMe stars. (orig./WL) [de

  15. An extended GS method for dense linear systems

    Science.gov (United States)

    Niki, Hiroshi; Kohno, Toshiyuki; Abe, Kuniyoshi

    2009-09-01

    Davey and Rosindale [K. Davey, I. Rosindale, An iterative solution scheme for systems of boundary element equations, Internat. J. Numer. Methods Engrg. 37 (1994) 1399-1411] derived the GSOR method, which uses an upper triangular matrix [Omega] in order to solve dense linear systems. By applying functional analysis, the authors presented an expression for the optimum [Omega]. Moreover, Davey and Bounds [K. Davey, S. Bounds, A generalized SOR method for dense linear systems of boundary element equations, SIAM J. Comput. 19 (1998) 953-967] also introduced further interesting results. In this note, we employ a matrix analysis approach to investigate these schemes, and derive theorems that compare these schemes with existing preconditioners for dense linear systems. We show that the convergence rate of the Gauss-Seidel method with preconditioner PG is superior to that of the GSOR method. Moreover, we define some splittings associated with the iterative schemes. Some numerical examples are reported to confirm the theoretical analysis. We show that the EGS method with preconditioner produces an extremely small spectral radius in comparison with the other schemes considered.

  16. Rheology of dense suspensions of non colloidal particles

    Science.gov (United States)

    Guazzelli, Élisabeth

    2017-06-01

    Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids that we will also address.

  17. Inferring segmented dense motion layers using 5D tensor voting.

    Science.gov (United States)

    Min, Changki; Medioni, Gérard

    2008-09-01

    We present a novel local spatiotemporal approach to produce motion segmentation and dense temporal trajectories from an image sequence. A common representation of image sequences is a 3D spatiotemporal volume, (x,y,t), and its corresponding mathematical formalism is the fiber bundle. However, directly enforcing the spatiotemporal smoothness constraint is difficult in the fiber bundle representation. Thus, we convert the representation into a new 5D space (x,y,t,vx,vy) with an additional velocity domain, where each moving object produces a separate 3D smooth layer. The smoothness constraint is now enforced by extracting 3D layers using the tensor voting framework in a single step that solves both correspondence and segmentation simultaneously. Motion segmentation is achieved by identifying those layers, and the dense temporal trajectories are obtained by converting the layers back into the fiber bundle representation. We proceed to address three applications (tracking, mosaic, and 3D reconstruction) that are hard to solve from the video stream directly because of the segmentation and dense matching steps, but become straightforward with our framework. The approach does not make restrictive assumptions about the observed scene or camera motion and is therefore generally applicable. We present results on a number of data sets.

  18. Rheology of dense suspensions of non colloidal particles

    Directory of Open Access Journals (Sweden)

    Guazzelli Élisabeth

    2017-01-01

    Full Text Available Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing and in natural phenomena (e.g. flows of slurries, debris, and lava. Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers or non-Newtonian fluids that we will also address.

  19. Carbon chemistry in dense molecular clouds: Theory and observational constraints

    International Nuclear Information System (INIS)

    Blake, G.A.

    1990-01-01

    For the most part, gas phase models of the chemistry of dense molecular clouds predict the abundances of simple species rather well. However, for larger molecules and even for small systems rich in carbon these models often fail spectacularly. Researchers present a brief review of the basic assumptions and results of large scale modeling of the carbon chemistry in dense molecular clouds. Particular attention is to the influence of the gas phase C/O ratio in molecular clouds, and the likely role grains play in maintaining this ratio as clouds evolve from initially diffuse objects to denser cores with associated stellar and planetary formation. Recent spectral line surveys at centimeter and millimeter wavelengths along with selected observations in the submillimeter have now produced an accurate inventory of the gas phase carbon budget in several different types of molecular clouds, though gaps in our knowledge clearly remain. The constraints these observations place on theoretical models of interstellar chemistry can be used to gain insights into why the models fail, and show also which neglected processes must be included in more complete analyses. Looking toward the future, larger molecules are especially difficult to study both experimentally and theoretically in such dense, cold regions, and some new methods are therefore outlined which may ultimately push the detectability of small carbon chains and rings to much heavier species

  20. Locating sources within a dense sensor array using graph clustering

    Science.gov (United States)

    Gerstoft, P.; Riahi, N.

    2017-12-01

    We develop a model-free technique to identify weak sources within dense sensor arrays using graph clustering. No knowledge about the propagation medium is needed except that signal strengths decay to insignificant levels within a scale that is shorter than the aperture. We then reinterpret the spatial coherence matrix of a wave field as a matrix whose support is a connectivity matrix of a graph with sensors as vertices. In a dense network, well-separated sources induce clusters in this graph. The geographic spread of these clusters can serve to localize the sources. The support of the covariance matrix is estimated from limited-time data using a hypothesis test with a robust phase-only coherence test statistic combined with a physical distance criterion. The latter criterion ensures graph sparsity and thus prevents clusters from forming by chance. We verify the approach and quantify its reliability on a simulated dataset. The method is then applied to data from a dense 5200 element geophone array that blanketed of the city of Long Beach (CA). The analysis exposes a helicopter traversing the array and oil production facilities.

  1. On parametrised cold dense matter equation of state inference

    Science.gov (United States)

    Riley, Thomas E.; Raaijmakers, Geert; Watts, Anna L.

    2018-04-01

    Constraining the equation of state of cold dense matter in compact stars is a major science goal for observing programmes being conducted using X-ray, radio, and gravitational wave telescopes. We discuss Bayesian hierarchical inference of parametrised dense matter equations of state. In particular we generalise and examine two inference paradigms from the literature: (i) direct posterior equation of state parameter estimation, conditioned on observations of a set of rotating compact stars; and (ii) indirect parameter estimation, via transformation of an intermediary joint posterior distribution of exterior spacetime parameters (such as gravitational masses and coordinate equatorial radii). We conclude that the former paradigm is not only tractable for large-scale analyses, but is principled and flexible from a Bayesian perspective whilst the latter paradigm is not. The thematic problem of Bayesian prior definition emerges as the crux of the difference between these paradigms. The second paradigm should in general only be considered as an ill-defined approach to the problem of utilising archival posterior constraints on exterior spacetime parameters; we advocate for an alternative approach whereby such information is repurposed as an approximative likelihood function. We also discuss why conditioning on a piecewise-polytropic equation of state model - currently standard in the field of dense matter study - can easily violate conditions required for transformation of a probability density distribution between spaces of exterior (spacetime) and interior (source matter) parameters.

  2. Rheological Behavior of Dense Assemblies of Granular Materials

    International Nuclear Information System (INIS)

    Sundaresan, Sankaran; Tardos, Gabriel I.; Subramaniam, Shankar

    2011-01-01

    Assemblies of granular materials behave differently when they are owing rapidly, from when they are slowly deforming. The behavior of rapidly owing granular materials, where the particle-particle interactions occur largely through binary collisions, is commonly related to the properties of the constituent particles through the kinetic theory of granular materials. The same cannot be said for slowly moving or static assemblies of granular materials, where enduring contacts between particles are prevalent. For instance, a continuum description of the yield characteristics of dense assemblies of particles in the quasistatic ow regime cannot be written explicitly on the basis of particle properties, even for cohesionless particles. Continuum models for this regime have been proposed and applied, but these models typically assume that the assembly is at incipient yield and they are expressed in terms of the yield function, which we do not yet know how to express in terms of particle-level properties. The description of the continuum rheology in the intermediate regime is even less understood. Yet, many practically important flows in nature and in a wide range of technological applications occur in the dense flow regime and at the transition between dilute and dense regimes; the lack of validated continuum rheological models for particle assemblies in these regimes limits predictive modeling of such flows. This research project is aimed at developing such rheological models.

  3. Enhanced Productivity of Chemical Processes Using Dense Fluidized Beds

    Energy Technology Data Exchange (ETDEWEB)

    Sibashis Banerjee; Alvin Chen; Rutton Patel; Dale Snider; Ken Williams; Timothy O' Hern; Paul Tortora

    2008-02-29

    The work detailed in this report addresses Enabling Technologies within Computational Technology by integrating a “breakthrough” particle-fluid computational technology into traditional Process Science and Engineering Technology. The work completed under this DOE project addresses five major development areas 1) gas chemistry in dense fluidized beds 2) thermal cracking of liquid film on solids producing gas products 3) liquid injection in a fluidized bed with particle-to-particle liquid film transport 4) solid-gas chemistry and 5) first level validation of models. Because of the nature of the research using tightly coupled solids and fluid phases with a Lagrangian description of the solids and continuum description of fluid, the work provides ground-breaking advances in reactor prediction capability. This capability has been tested against experimental data where available. The commercial product arising out of this work is called Barracuda and is suitable for a wide (dense-to-dilute) range of industrial scale gas-solid flows with and without reactions. Commercial applications include dense gas-solid beds, gasifiers, riser reactors and cyclones.

  4. Isotopologues of dense gas tracers in NGC 1068

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junzhi; Qiu, Jianjie [Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, 200030, Shanghai (China); Zhang, Zhi-Yu [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Shi, Yong [School of Astronomy and Space Science, Nanjing University, Nanjing, 210093 (China); Zhang, Jiangshui [Center For Astrophysics, GuangZhou University, 510006, GuangZhou (China); Fang, Min, E-mail: jzwang@shao.ac.cn [ESO, Karl Schwarzschild Strasse 2, D-85748 Garching bei Munich (Germany)

    2014-11-20

    We present observations of isotopic lines of dense gas tracers toward the nuclear region of nearby Seyfert 2 galaxy NGC 1068 with the IRAM 30 m telescope and the Atacama Pathfinder Experiment (APEX) 12 m telescope. We detected four isotopic lines (H{sup 13}CN 1-0, H{sup 13}CO{sup +} 1-0, HN{sup 13}C 1-0, and HC{sup 18}O{sup +} 1-0) at the 3 mm band with the IRAM 30 m telescope and obtained upper limits of other lines. We calculated optical depths of dense gas tracers with the detected isotopic lines of HCN 1-0, HCO{sup +} 1-0, and HNC 1-0. We find that the {sup 14}N/{sup 15}N abundance ratio is greater than 420 if we adopt the upper limit of HC{sup 15}N(1-0) emission. Combining this with fluxes of 1-0 lines from IRAM 30 m observations and the upper limit of 3-2 lines from APEX 12 m observations, we also estimated the excitation condition of molecular gas in the nuclear region of NGC 1068, which is less dense than that in the extreme starburst regions of galaxies.

  5. The effect of dense phase carbon dioxide on the conformation of hemoglobin.

    Science.gov (United States)

    Yan, Wenjie; Xie, Yangyang; Wang, Xiaoxi; Jia, Fei; Li, Xingmin

    2018-04-01

    Dense phase carbon dioxide (DPCD) sterilization is a non-thermal sterilization technology used to process heat-sensitive foods. Although nutritional and sensorial quality of food is preserved while unwanted microbial activity is reduced during DPCD sterilization, the effect on protein structure remains unclear. In this work, the effect of DPCD on the higher order structure and fluorescence properties of Hemoglobin (Hb) was investigated. The different conditions assessed during DPCD processing included variation in pressure, pH and heating conditions. Results from this study showed an inversely proportional correlation between α-helical content of Hb and pressure. As the pressure was lowered, the levels of α-helical content increased. The increased levels of α-helix correlated with a lower fluorescence intensity and a limited redshift in the fluorescence emission wavelength. TEM imaging showed that DPCD processing resulted in Hb with larger molecular diameters, which became smaller as the pressure increased. Interestingly, after 7-day storage at 4 °C, an increase in α-helical content was observed. Results from this work show that DPCD sterilization does impact the conformation of hemoglobin, with a notable impact on secondary and tertiary structure. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Ultra High Intensity laser produced fast electron transport in under-dense and over-dense matter

    International Nuclear Information System (INIS)

    Manclossi, Mauro

    2006-01-01

    This thesis is related to inertial fusion research, and particularly concerns the approach to fast ignition, which is based on the use of ultra-intense laser pulses to ignite the thermonuclear fuel. Until now, the feasibility of this scheme has not been proven and depends on many fundamental aspects of the underlying physics, which are not yet fully understood and which are also very far from controls. The main purpose of this thesis is the experimental study of transport processes in the material over-dense (solid) and under-dense (gas jet) of a beam of fast electrons produced by pulse laser at a intensity of some 10 19 Wcm -2 . (author)

  7. Prediction of a Densely Loaded Particle-Laden Jet using a Euler-Lagrange Dense Spray Model

    Science.gov (United States)

    Pakseresht, Pedram; Apte, Sourabh V.

    2017-11-01

    Modeling of a dense spray regime using an Euler-Lagrange discrete-element approach is challenging because of local high volume loading. A subgrid cluster of droplets can lead to locally high void fractions for the disperse phase. Under these conditions, spatio-temporal changes in the carrier phase volume fractions, which are commonly neglected in spray simulations in an Euler-Lagrange two-way coupling model, could become important. Accounting for the carrier phase volume fraction variations, leads to zero-Mach number, variable density governing equations. Using pressure-based solvers, this gives rise to a source term in the pressure Poisson equation and a non-divergence free velocity field. To test the validity and predictive capability of such an approach, a round jet laden with solid particles is investigated using Direct Numerical Simulation and compared with available experimental data for different loadings. Various volume fractions spanning from dilute to dense regimes are investigated with and without taking into account the volume displacement effects. The predictions of the two approaches are compared and analyzed to investigate the effectiveness of the dense spray model. Financial support was provided by National Aeronautics and Space Administration (NASA).

  8. 1991 US-Japan workshop on Nuclear Fusion in Dense Plasmas

    International Nuclear Information System (INIS)

    Ichimaru, S.; Tajima, T.

    1991-10-01

    The scientific areas covered at the Workshop may be classified into the following subfields: (1) basic theory of dense plasma physics and its interface with atomic physics and nuclear physics; (2) physics of dense z-pinches, ICF plasmas etc; (3) stellar interior plasmas; (4) cold fusion; and (5) other dense plasmas

  9. Wet skins tanning with chromium in dense CO{sub 2} under pressure; Tannage au chrome de peaux humides en CO{sub 2} dense sous pression

    Energy Technology Data Exchange (ETDEWEB)

    Saldinari, L. [Tanneries Roux SA, 26 - Romans Sur Isere (France)]|[Tanneries du Puy (France)]|[Tanneries d' Annonay, 07 (France); Dutel, Ch. [Societe ATC (France); Perre, Ch. [CEA Centre de Pierrelatte (DCC/DTE/SLC), 26 (France)

    2000-07-01

    An ancestral gesture steadily improved through the centuries, the transformation of skins into leather includes several stages of which the principal one is tanning. Today, 90 % of the world's leather products are tanned with chromium. However, this stage is an environmental liability, and reducing the volume and chromium content of the waste has become a major issue. A first study on skin degreasing by dense CO{sub 2} helped sharply reduce the volume of the fatty effluents. To replace water by dense CO{sub 2} as the tanning medium was the logical next step. The present study was carried out in cooperation with three tanneries in the Rhone-Alpes-Auvergne area of France and a manufacturer of tanning materials. The difficulty of the study was the chemically opposed character of the two media involved. CO{sub 2} is a non-polar and lipophilic solvent while inorganic chromium is insoluble. The water present in the treated skin is a polar and ionic reaction medium and one of the reagents in tanning chemistry. The mixture of these two partially miscible compounds gives a pH 3 by carbonic acid formation. Tanning is based on the reactivity of collagen, the main component of the skin, with hydroxylated complexes of chromium. Collagen is a protein containing some chemical functions, amines (R-NH{sub 2}) and carboxylic (R-COOH) for example. These functions impart an amphoteric character to the compound. The WERNER theory of complex salts explains the formation of hydroxylated complexes of chromium and their fixing on the carboxylic functions of collagen by oxolation. pH is the key parameter in tanning. The success of the process demands chromium impregnation without fixing it at a pH lower than 5, and then to fix it by increasing the pH. This opened two alternatives for transferring chromium in the skin: solubilize chromium in CO{sub 2} via soluble organometallic complexes; or put the chromium salt into suspension without solubilizing it. The best results were obtained

  10. Bayesian quantification of thermodynamic uncertainties in dense gas flows

    International Nuclear Information System (INIS)

    Merle, X.; Cinnella, P.

    2015-01-01

    A Bayesian inference methodology is developed for calibrating complex equations of state used in numerical fluid flow solvers. Precisely, the input parameters of three equations of state commonly used for modeling the thermodynamic behavior of the so-called dense gas flows, – i.e. flows of gases characterized by high molecular weights and complex molecules, working in thermodynamic conditions close to the liquid–vapor saturation curve – are calibrated by means of Bayesian inference from reference aerodynamic data for a dense gas flow over a wing section. Flow thermodynamic conditions are such that the gas thermodynamic behavior strongly deviates from that of a perfect gas. In the aim of assessing the proposed methodology, synthetic calibration data – specifically, wall pressure data – are generated by running the numerical solver with a more complex and accurate thermodynamic model. The statistical model used to build the likelihood function includes a model-form inadequacy term, accounting for the gap between the model output associated to the best-fit parameters and the true phenomenon. Results show that, for all of the relatively simple models under investigation, calibrations lead to informative posterior probability density distributions of the input parameters and improve the predictive distribution significantly. Nevertheless, calibrated parameters strongly differ from their expected physical values. The relationship between this behavior and model-form inadequacy is discussed. - Highlights: • Development of a Bayesian inference procedure for calibrating dense-gas flow solvers. • Complex thermodynamic models calibrated by using aerodynamic data for the flow. • Preliminary Sobol analysis used to reduce parameter space. • Piecewise polynomial surrogate model constructed to reduce computational cost. • Calibration results show the crucial role played by model-form inadequacies

  11. Monocular oral reading after treatment of dense congenital unilateral cataract

    Science.gov (United States)

    Birch, Eileen E.; Cheng, Christina; Christina, V; Stager, David R.

    2010-01-01

    Background Good long-term visual acuity outcomes for children with dense congenital unilateral cataracts have been reported following early surgery and good compliance with postoperative amblyopia therapy. However, treated eyes rarely achieve normal visual acuity and there has been no formal evaluation of the utility of the treated eye for reading. Methods Eighteen children previously treated for dense congenital unilateral cataract were tested monocularly with the Gray Oral Reading Test, 4th edition (GORT-4) at 7 to 13 years of age using two passages for each eye, one at grade level and one at +1 above grade level. In addition, right eyes of 55 normal children age 7 to 13 served as a control group. The GORT-4 assesses reading rate, accuracy, fluency, and comprehension. Results Visual acuity of treated eyes ranged from 0.1 to 2.0 logMAR and of fellow eyes from −0.1 to 0.2 logMAR. Treated eyes scored significantly lower than fellow and normal control eyes on all scales at grade level and at +1 above grade level. Monocular reading rate, accuracy, fluency, and comprehension were correlated with visual acuity of treated eyes (rs = −0.575 to −0.875, p < 0.005). Treated eyes with 0.1-0.3 logMAR visual acuity did not differ from fellow or normal control eyes in rate, accuracy, fluency, or comprehension when reading at grade level or at +1 above grade level. Fellow eyes did not differ from normal controls on any reading scale. Conclusions Excellent visual acuity outcomes following treatment of dense congenital unilateral cataracts are associated with normal reading ability of the treated eye in school-age children. PMID:20603057

  12. Parallel Access of Out-Of-Core Dense Extendible Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Otoo, Ekow J; Rotem, Doron

    2007-07-26

    Datasets used in scientific and engineering applications are often modeled as dense multi-dimensional arrays. For very large datasets, the corresponding array models are typically stored out-of-core as array files. The array elements are mapped onto linear consecutive locations that correspond to the linear ordering of the multi-dimensional indices. Two conventional mappings used are the row-major order and the column-major order of multi-dimensional arrays. Such conventional mappings of dense array files highly limit the performance of applications and the extendibility of the dataset. Firstly, an array file that is organized in say row-major order causes applications that subsequently access the data in column-major order, to have abysmal performance. Secondly, any subsequent expansion of the array file is limited to only one dimension. Expansions of such out-of-core conventional arrays along arbitrary dimensions, require storage reorganization that can be very expensive. Wepresent a solution for storing out-of-core dense extendible arrays that resolve the two limitations. The method uses a mapping function F*(), together with information maintained in axial vectors, to compute the linear address of an extendible array element when passed its k-dimensional index. We also give the inverse function, F-1*() for deriving the k-dimensional index when given the linear address. We show how the mapping function, in combination with MPI-IO and a parallel file system, allows for the growth of the extendible array without reorganization and no significant performance degradation of applications accessing elements in any desired order. We give methods for reading and writing sub-arrays into and out of parallel applications that run on a cluster of workstations. The axial-vectors are replicated and maintained in each node that accesses sub-array elements.

  13. Laterally cyclic loading of monopile in dense sand

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Hededal, Ole; Svensson, M.

    2011-01-01

    In order to investigate the response from laterally cyclic loading of monopiles a large centrifuge tests series is ongoing at the Technical University of Denmark (DTU). This paper will present some of the tests carried out with a focus on the influence of accumulation of rotation when changing...... the loading conditions. In these tests the load conditions are controlled by two load characteristics, one controlling the level of the cyclic loading and one controlling the characteristic of the cyclic loading. The centrifuge tests were performed in dense dry sand on a pile with prototype dimensions...

  14. Repetitively pulsed capacitor bank for the dense-plasma focus

    International Nuclear Information System (INIS)

    Zucker, O.; Bostick, W.; Gullickson, R.; Long, J.; Luce, J.; Sahlin, H.

    1975-12-01

    This report describes a 1 pulse per second capacitor bank designed to energize a dense-plasma focus (DPF). The DPF is a neutron source capable (with moderate scaling) of delivering a minimum of 10 15 neutrons per pulse or neutron flux of 2 x 10 13 N/cm 2 .s. The average power consumption, which has become a major issue due to the energy crisis, is analyzed with respect to other plasma devices and is shown to be highly favorable. This small source size high flux neutron source could be extemely useful to qualify fission reactor material irradiation results for fusion reactor design

  15. Chemical potential calculations in dense liquids using metadynamics

    Science.gov (United States)

    Perego, C.; Giberti, F.; Parrinello, M.

    2016-10-01

    The calculation of chemical potential has traditionally been a challenge in atomistic simulations. One of the most used approaches is Widom's insertion method in which the chemical potential is calculated by periodically attempting to insert an extra particle in the system. In dense systems this method fails since the insertion probability is very low. In this paper we show that in a homogeneous fluid the insertion probability can be increased using metadynamics. We test our method on a supercooled high density binary Lennard-Jones fluid. We find that we can obtain efficiently converged results even when Widom's method fails.

  16. Coherent scattering of neutrinos by 'nuclear pasta' in dense matter

    International Nuclear Information System (INIS)

    Sonoda, Hidetaka

    2007-01-01

    We examine coherent scattering cross section of neutrino and nucleon systems via weak-neutral current at subnuclear densities, which will be important in supernova cores. Below melting density and temparature of nuclei, nuclear shape becomes rodlike and slablike; this is called nuclear 'pasta'. Transition of structure will greatly influence coherent effects which can not easily be predicted. We calculate static structure factor of nuclear matter using data of several nuclear models, and discuss the effects of existence of nuclear pasta on neutrino opacity in hot dense matter

  17. Performance analysis of simultaneous dense coding protocol under decoherence

    Science.gov (United States)

    Huang, Zhiming; Zhang, Cai; Situ, Haozhen

    2017-09-01

    The simultaneous dense coding (SDC) protocol is useful in designing quantum protocols. We analyze the performance of the SDC protocol under the influence of noisy quantum channels. Six kinds of paradigmatic Markovian noise along with one kind of non-Markovian noise are considered. The joint success probability of both receivers and the success probabilities of one receiver are calculated for three different locking operators. Some interesting properties have been found, such as invariance and symmetry. Among the three locking operators we consider, the SWAP gate is most resistant to noise and results in the same success probabilities for both receivers.

  18. On the spatial distributions of dense cores in Orion B

    Science.gov (United States)

    Parker, Richard J.

    2018-05-01

    We quantify the spatial distributions of dense cores in three spatially distinct areas of the Orion B star-forming region. For L1622, NGC 2068/NGC 2071, and NGC 2023/NGC 2024, we measure the amount of spatial substructure using the Q-parameter and find all three regions to be spatially substructured (Q Orion B, the mass segregation cannot be dynamical. Our results are also inconsistent with simulations in which the most massive stars form via competitive accretion, and instead hint that magnetic fields may be important in influencing the primordial spatial distributions of gas and stars in star-forming regions.

  19. Ultrasound propagation in dense aerogels filled with liquid 4He

    International Nuclear Information System (INIS)

    Matsumoto, K; Ohmori, K; Abe, S; Kanamori, K; Nakanishi, K

    2012-01-01

    Longitudinal ultrasound propagation was studied in dense aerogels filled with liquid 4 He. Sound velocity and attenuation were measured at the frequency of 6 MHz in both normal and superfluid phases. Pressure dependence of velocity and attenuation were also studied. Studied aerogels had porosities about 85%. They had two different types of structure, tangled strand structure and aggregated particles structure. The pore size distributions were narrow. Reduction of superfluid transition temperature mainly depended on not porosity but mean pore size. The structure of gel played an important role in sound velocity and attenuation.

  20. Probing hot dense matter with jet energy loss

    International Nuclear Information System (INIS)

    Levai, P.; Barnafoeldi, G.G.; Gyulassy, M.; Vitev, I.; Fai, G.; Zhang, Y.

    2002-01-01

    We study, in a pQCD calculation augmented by nuclear effects, the jet energy loss needed to reproduce the π 0 spectra in Au+Au collisions at large p T , measured by PHENIX at RHIC. The transverse width of the parton momentum distributions (intrinsic k T ) is used phenomenologically to obtain a reliable baseline pp result. Jet quenching is applied to the nuclear spectra (including shadowing and multiscattering) to fit the data. Latest results on fluctuating gluon radiation are considered to measure the opacity of the produced hot dense matter at RHIC energy. (orig.)