WorldWideScience

Sample records for graded nanometal particles

  1. Magnetic Properties of Nanometer-sized Crystalline and Amorphous Particles

    DEFF Research Database (Denmark)

    Mørup, Steen; Bødker, Franz; Hansen, Mikkel Fougt

    1997-01-01

    Amorphous transition metal-metalloid alloy particles can be prepared by chemical preparation techniques. We discuss the preparation of transition metal-boron and iron-carbon particles and their magnetic properties. Nanometer-sized particles of both crystalline and amorphous magnetic materials...... are superparamagnetic at finite temperatures. The temperature dependence of the superparamagnetic relaxation time and the influence of inter-particle interactions is discussed. Finally, some examples of studies of surface magnetization of alpha-Fe particles are presented....

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

    Science.gov (United States)

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

    2010-01-01

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

  3. Fluorescent gel particles in the nanometer range for detection of metabolites in living cells

    DEFF Research Database (Denmark)

    Almdal, K.; Sun, H.; Poulsen, A.K.

    2006-01-01

    micelles in oil microemulsions. Typical sizes of the particles are tens of nanometers. Characterization methods for such particles based on size exclusion chromatography, photon correlation spectroscopy, scanning electron microscopy, and atomic force microscopy have been developed. The stability...

  4. Fractal-like dimension of nanometer Diesel soot particles

    Energy Technology Data Exchange (ETDEWEB)

    Skillas, G.; Baltensperger, U. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Siegmann, K. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-11-01

    Measurements with a low-pressure impactor and a differential mobility analyser were conducted for Diesel soot at various engine loads. By means of these measurements a fractal-like dimension of Diesel soot particles, with diameters ranging from 55 up to 260 nm, was established. (author) 2 figs., 7 refs.

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

    Science.gov (United States)

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

    2001-12-01

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

  6. Obtaining of iron particles of nanometer size in a natural zeolite

    International Nuclear Information System (INIS)

    Xingu C, E. G.

    2013-01-01

    The zeolites are aluminosilicates with cavities that can act as molecular sieve. Their crystalline structure is formed by tetrahedrons that get together giving place to a three-dimensional net, in which each oxygen is shared by two silicon atoms, being this way part of the tecto silicate minerals, its external and internal areas reach the hundred square meters for gram, they are located in a natural way in a large part of earth crust and also exist in a synthetic way. In Mexico there are different locations of zeolitic material whose important component is the clinoptilolite. In this work the results of three zeolitic materials coming from San Luis Potosi are shown, the samples were milled and sieved for its initial characterization, to know its chemical composition, crystalline phases, morphology, topology and thermal behavior before and after its homo-ionization with sodium chloride, its use as support of iron particles of nanometer size. The description of the synthesis of iron particles of nanometer size is also presented, as well as the comparison with the particles of nanometer size synthesized without support after its characterization. The characterization techniques used during the experimental work were: Scanning electron microscopy, X-ray diffraction, Infrared spectroscopy, specific area by means of BET and thermogravimetry analysis. (Author)

  7. Modulation of Magnetic Properties at the Nanometer Scale in Continuously Graded Ferromagnets

    Directory of Open Access Journals (Sweden)

    Lorenzo Fallarino

    2018-02-01

    Full Text Available Ferromagnetic alloy materials with designed composition depth profiles provide an efficient route for the control of magnetism at the nanometer length scale. In this regard, cobalt-chromium and cobalt-ruthenium alloys constitute powerful model systems. They exhibit easy-to-tune magnetic properties such as saturation magnetization MS and Curie temperature TC while preserving their crystalline structure over a wide composition range. In order to demonstrate this materials design potential, we have grown a series of graded Co1−xCrx and Co1−wRuw (10 1 ¯ 0 epitaxial thin films, with x and w following predefined concentration profiles. Structural analysis measurements verify the epitaxial nature and crystallographic quality of our entire sample sets, which were designed to exhibit in-plane c-axis orientation and thus a magnetic in-plane easy axis to achieve suppression of magnetostatic domain generation. Temperature and field-dependent magnetic depth profiles have been measured by means of polarized neutron reflectometry. In both investigated structures, TC and MS are found to vary as a function of depth in accordance with the predefined compositional depth profiles. Our Co1−wRuw sample structures, which exhibit very steep material gradients, allow us to determine the localization limit for compositionally graded materials, which we find to be of the order of 1 nm. The Co1−xCrx systems show the expected U-shaped TC and MS depth profiles, for which these specific samples were designed. The corresponding temperature dependent magnetization profile is then utilized to control the coupling along the film depth, which even allows for a sharp onset of decoupling of top and bottom sample parts at elevated temperatures.

  8. Nanometer, submicron and micron sized aluminum powder prepared by semi-solid mechanical stirring method with addition of ceramic particles

    International Nuclear Information System (INIS)

    Qin, X.H.; Jiang, D.L.; Dong, S.M.

    2004-01-01

    Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50-900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2009-12-10

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

  11. Enhanced Laser Cooling of Rare-Earth-Ion-Doped Glass Containing Nanometer-Sized Metallic Particles

    International Nuclear Information System (INIS)

    Jia Youhua; Zhong Biao; Yin Jianping

    2009-01-01

    The enhanced laser cooling performance of rare-earth-ions-doped glasses containing small particles is predicted. This is achieved by the enhancement of local field around rare earth ions, owing to the surface plasmon resonance of small metallic particles. The role of energy transfer between ions and the particle is theoretical discussed. Depending on the particle size and the ion emission quantum efficiency, the enhancement of the absorption and the fluorescence is predicted. Moreover, taking Yb 3+ -doped ZBLAN as example, the cooling power and heat-light converting efficiency are calculated. It is finally concluded that the absorption and the fluorescence are greatly enhanced in these composite materials, the cooling power is increased compared to the bulk material. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

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

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

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

  13. Capture and alignment of phi29 viral particles in sub-40 nanometer porous alumina membranes.

    Science.gov (United States)

    Moon, Jeong-Mi; Akin, Demir; Xuan, Yi; Ye, Peide D; Guo, Peixuan; Bashir, Rashid

    2009-02-01

    Bacteriophage phi29 virus nanoparticles and its associated DNA packaging nanomotor can provide for novel possibilities towards the development of hybrid bio-nano structures. Towards the goal of interfacing the phi29 viruses and nanomotors with artificial micro and nanostructures, we fabricated nanoporous Anodic Aluminum Oxide (AAO) membranes with pore size of 70 nm and shrunk the pores to sub 40 nm diameter using atomic layer deposition (ALD) of Aluminum Oxide. We were able to capture and align particles in the anodized nanopores using two methods. Firstly, a functionalization and polishing process to chemically attach the particles in the inner surface of the pores was developed. Secondly, centrifugation of the particles was utilized to align them in the pores of the nanoporous membranes. In addition, when a mixture of empty capsids and packaged particles was centrifuged at specific speeds, it was found that the empty capsids deform and pass through 40 nm diameter pores whereas the particles packaged with DNA were mainly retained at the top surface of the nanoporous membranes. Fluorescence microscopy was used to verify the selective filtration of empty capsids through the nanoporous membranes.

  14. Growth Processes of Particles up to Nanometer in High-Frequency SiH4 Plasmas

    International Nuclear Information System (INIS)

    Watanabe, Y.; Shiratani, M.; Fukuzawa, T.; Koga, K.

    2000-01-01

    Growth processes of particles in high-frequency SiH 4 discharges have been understood fairly well in a size range above 10 nm. Recently, we have developed two in situ particle detection methods to study those of particles (clusters) in a size range below ∼ 10 nm. The studies have clarified time evolution of their density and size and revealed the following facts: the cluster density amounts to ∼ 10 11 cm -3 under the device quality low-power and low-pressure conditions: the discharge modulation, substrate heating and H 2 dilution are quite effective in suppressing the cluster growth. We have proposed the cluster growth model explaining reasonably the obtained results. (author)

  15. Probing Single Nanometer-scale Particles with Scanning Tunneling Microscopy and Spectroscopies

    International Nuclear Information System (INIS)

    McCarty, G.S.; Love, J.C.; Kushmerick, J.G.; Charles, L.F.; Keating, C.D.; Toleno, B.J.; Lyn, M.E.; Castleman, A.W.; Natan, M.J.; Weiss, P.S.

    1999-01-01

    Scanning tunneling microscopy can be used to isolate single particles on surfaces for further study. Local optical and electronic properties coupled with topographic information collected by the scanning tunneling microscope (STM) give insight into the intrinsic properties of the species under study. Since each spectroscopic measurement is done on a single particle, each sample is 'monodisperse', regardless of the degree of heterogeneity of the original preparation. We illustrate this with three example systems - a metal cluster of known atomic structure, metal nanoparticles dispersed from colloid suspensions, and metallocarbohedrenes (Met-Cars) deposited with other reaction products. Au and Ag nanoparticles were imaged using a photon emission STM. The threshold voltage, the lowest bias voltage at which photons are produced, was determined for Au nanoparticles. Electronic spectra of small clusters of Ni atoms on MoS 2 were recorded. Preliminary images of Zr-based Met-Car-containing soot were obtained on Au and MoS 2 substrates and partial electronic spectra were recorded of these possible Met-Car particles

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zachary J Smith

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

  18. Inorganic particle synthesis via macro and microemulsions a micrometer to nanometer landscape

    CERN Document Server

    Ganguli, Dibyendu

    2003-01-01

    "Nanotechnology" is now very well known as one of the most important key technologies in science and industry. In the field of material science and engineering, nanoparticles should be unit materials, as well as atoms and molecules, to build ceramics, devices, catalysts, and machines, and the "nanoparticle technology" is thus attracting. This novel technology includes various methodologies for nanoparticles: preparation, surface-modification via chemical and/or physical treatments, immobilization and arrangement on supports or substrates, to achieve high performance for luminescence properties in light emitting devices, and high efficiency for catalytic and photocatalytic reactions in chemical synthesis, chemical decomposition, and artificial photosynthesis, etc. It should be needless to say that the preparation of nanoparticles, having precisely controlled particle size, size distribution, chemical composition, and surface properties, is essentially important to realize "true nanoparticle technology". This b...

  19. Surface modification and characterization for dispersion stability of inorganic nanometer-scaled particles in liquid media

    International Nuclear Information System (INIS)

    Kamiya, Hidehiro; Iijima, Motoyuki

    2010-01-01

    Inorganic nanoparticles are indispensable for science and technology as materials, pigments and cosmetics products. Improving the dispersion stability of nanoparticles in various liquids is essential for those applications. In this review, we discuss why it is difficult to control the stability of nanoparticles in liquids. We also overview the role of surface interaction between nanoparticles in their dispersion and characterization, e.g. by colloid probe atomic force microscopy (CP-AFM). Two types of surface modification concepts, post-synthesis and in situ modification, were investigated in many previous studies. Here, we focus on post-synthesis modification using adsorption of various kinds of polymer dispersants and surfactants on the particle surface, as well as surface chemical reactions of silane coupling agents. We discuss CP-AFM as a technique to analyze the surface interaction between nanoparticles and the effect of surface modification on the nanoparticle dispersion in liquids. (topical review)

  20. Surface modification and characterization for dispersion stability of inorganic nanometer-scaled particles in liquid media

    Directory of Open Access Journals (Sweden)

    Hidehiro Kamiya and Motoyuki Iijima

    2010-01-01

    Full Text Available Inorganic nanoparticles are indispensable for science and technology as materials, pigments and cosmetics products. Improving the dispersion stability of nanoparticles in various liquids is essential for those applications. In this review, we discuss why it is difficult to control the stability of nanoparticles in liquids. We also overview the role of surface interaction between nanoparticles in their dispersion and characterization, e.g. by colloid probe atomic force microscopy (CP-AFM. Two types of surface modification concepts, post-synthesis and in situ modification, were investigated in many previous studies. Here, we focus on post-synthesis modification using adsorption of various kinds of polymer dispersants and surfactants on the particle surface, as well as surface chemical reactions of silane coupling agents. We discuss CP-AFM as a technique to analyze the surface interaction between nanoparticles and the effect of surface modification on the nanoparticle dispersion in liquids.

  1. Obtaining of iron particles of nanometer size in a natural zeolite; Obtencion de particulas de hierro de tamano nanometrico en una zeolita natural

    Energy Technology Data Exchange (ETDEWEB)

    Xingu C, E. G.

    2013-07-01

    The zeolites are aluminosilicates with cavities that can act as molecular sieve. Their crystalline structure is formed by tetrahedrons that get together giving place to a three-dimensional net, in which each oxygen is shared by two silicon atoms, being this way part of the tecto silicate minerals, its external and internal areas reach the hundred square meters for gram, they are located in a natural way in a large part of earth crust and also exist in a synthetic way. In Mexico there are different locations of zeolitic material whose important component is the clinoptilolite. In this work the results of three zeolitic materials coming from San Luis Potosi are shown, the samples were milled and sieved for its initial characterization, to know its chemical composition, crystalline phases, morphology, topology and thermal behavior before and after its homo-ionization with sodium chloride, its use as support of iron particles of nanometer size. The description of the synthesis of iron particles of nanometer size is also presented, as well as the comparison with the particles of nanometer size synthesized without support after its characterization. The characterization techniques used during the experimental work were: Scanning electron microscopy, X-ray diffraction, Infrared spectroscopy, specific area by means of BET and thermogravimetry analysis. (Author)

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

    Science.gov (United States)

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

    2018-03-01

    Elevated metallic nanostructures with nanogaps (film deposition. By controlling the initial size of nanogaps in resist structures and the following deposited film thickness, metallic nanogaps could be tuned at the sub-10 nm scale with single-digit nanometer precision. Both experimental and simulated results revealed that gold dimer on mushroom-shaped pillars have the capability to achieve higher SERS enhancement factor comparing to those plasmonic dimers on cylindrical pillars or on a common SiO2/Si substrate, implying that the nanometer-gapped elevated dimer is an ideal platform to achieve the highest possible field enhancement for various plasmonic applications.

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

    Science.gov (United States)

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

    2018-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Shunsuke Asahina

    2014-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Asahina, Shunsuke; Suga, Mitsuo; Takahashi, Hideyuki [JEOL Ltd., SM Business Unit, Tokyo (Japan); Young Jeong, Hu [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Galeano, Carolina; Schüth, Ferdi [Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim (Germany); Terasaki, Osamu, E-mail: terasaki@mmk.su.se, E-mail: terasaki@kaist.ac.kr [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Department of Materials and Environmental Chemistry, Berzelii Centre EXSELENT on Porous Materials, Stockholm University, SE-10691 Stockholm (Sweden)

    2014-11-01

    Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in yolk-shell materials of Au@C, Ru/Pt@C, Au@TiO{sub 2}, and Pt@Polymer. Progresses in the following categories were shown for the yolk-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

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

    Science.gov (United States)

    Emerson, Sean Christian

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

  7. Photocatalytic performances of BiFeO3 particles with the average size in nanometer, submicrometer, and micrometer

    International Nuclear Information System (INIS)

    Hao, Chunxue; FushengWen,; Xiang, Jianyong; Hou, Hang; Lv, Weiming; Lv, Yifei; Hu, Wentao; Liu, Zhongyuan

    2014-01-01

    Highlights: • Three different synthesis routes have been taken to successfully prepare the BiFeO 3 particles with the different morphologies and average size in 50, 500 nm, and 15 μm. • For photodegradation of dyes under visible irradiation in the presence of BiFeO 3 , the photocatalytic efficiency increases quickly with the decrease in size. • The enhanced photocatalytic efficiency of BiFeO 3 nanoparticles may attribute to more surface active catalytic-sites and shorter distances carriers have to migrate to the surface reaction sites. - Abstract: Three different synthesis routes were taken to successfully prepare the BiFeO 3 particles with the different morphologies and average size in 50, 500 nm, and 15 μm, respectively. The crystal structure was recognized to be a distorted rhombohedral one with the space group R3c. With the decrease in particle size, obvious decrease in peak intensity and redshift in peak position were observed for the Raman active bands. The narrow band gap was determined from the UV–vis absorption spectra, indicating the semiconducting nature of the BiFeO 3 . For photodegradation of dyes under visible irradiation in the presence of BiFeO 3 , the photocatalytic efficiency increased quickly with the decrease in size which may attribute to more surface active catalytic-sites and shorter distances carriers had to migrate to the surface reaction sites

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

    Science.gov (United States)

    Tammet, H.

    2006-12-01

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

  9. Nanometer size diesel exhaust particles are selectively toxic to dopaminergic neurons: the role of microglia, phagocytosis, and NADPH oxidase.

    Science.gov (United States)

    Block, M L; Wu, X; Pei, Z; Li, G; Wang, T; Qin, L; Wilson, B; Yang, J; Hong, J S; Veronesi, B

    2004-10-01

    The contributing role of environmental factors to the development of Parkinson's disease has become increasingly evident. We report that mesencephalic neuron-glia cultures treated with diesel exhaust particles (DEP; 0.22 microM) (5-50 microg/ml) resulted in a dose-dependent decrease in dopaminergic (DA) neurons, as determined by DA-uptake assay and tyrosine-hydroxylase immunocytochemistry (ICC). The selective toxicity of DEP for DA neurons was demonstrated by the lack of DEP effect on both GABA uptake and Neu-N immunoreactive cell number. The critical role of microglia was demonstrated by the failure of neuron-enriched cultures to exhibit DEP-induced DA neurotoxicity, where DEP-induced DA neuron death was reinstated with the addition of microglia to neuron-enriched cultures. OX-42 ICC staining of DEP treated neuron-glia cultures revealed changes in microglia morphology indicative of activation. Intracellular reactive oxygen species and superoxide were produced from enriched-microglia cultures in response to DEP. Neuron-glia cultures from NADPH oxidase deficient (PHOX-/-) mice were insensitive to DEP neurotoxicity when compared with control mice (PHOX+/+). Cytochalasin D inhibited DEP-induced superoxide production in enriched-microglia cultures, implying that DEP must be phagocytized by microglia to produce superoxide. Together, these in vitro data indicate that DEP selectively damages DA neurons through the phagocytic activation of microglial NADPH oxidase and consequent oxidative insult.

  10. Development of a picture of the van der Waals interaction energy between clusters of nanometer-range particles

    International Nuclear Information System (INIS)

    Arunachalam, V.; Marlow, W.H.; Lu, J.X.

    1998-01-01

    The importance of the long-range Lifshitz-van der Waals interaction energy between condensed bodies is well known. However, its implementation for interacting bodies that are highly irregular and separated by distances varying from contact to micrometers has received little attention. As part of a study of collisions of irregular aerosol particles, an approach based on the Lifshitz theory of van der Waals interaction has been developed to compute the interaction energy between a sphere and an aggregate of spheres at all separations. In the first part of this study, the iterated sum-over-dipole interactions between pairs of approximately spherical molecular clusters are compared with the Lifshitz and Lifshitz-Hamaker interaction energies for continuum spheres of radii equal to those of the clusters' circumscribed spheres and of the same masses as the clusters. The Lifshitz energy is shown to converge to the iterated dipolar energy for quasispherical molecular clusters for sufficiently large separations, while the energy calculated by using the Lifshitz-Hamaker approach does not. Next, the interaction energies between a contacting pair of these molecular clusters and a third cluster in different relative positions are calculated first by coupling all molecules in the three-cluster system and second by ignoring the interactions between the molecules of the adhering clusters. The error calculated by this omission is shown to be very small, and is an indication of the error in computing the long-range interaction energy between a pair of interacting spheres and a third sphere as a simple sum over the Lifshitz energies between individual, condensed-matter spheres. This Lifshitz energy calculation is then combined with the short-separation, nonsingular van der Waals energy calculation of Lu, Marlow, and Arunachalam, to provide an integrated picture of the van der Waals energy from large separations to contact. copyright 1998 The American Physical Society

  11. Dispersion effect and auto-reconditioning performance of nanometer ...

    Indian Academy of Sciences (India)

    This paper reported on dispersion effect and dispersing techniques of nanometer WS2 particles in the green lubricant concocted by us. And it also researched on auto-reconditioning performance of nanometer WS2 particles to the abrasive surfaces of steel ball from four-ball tribology test and piston ring from engine ...

  12. Encapsulation of resveratrol in spherical particles of food grade hydrogels

    Directory of Open Access Journals (Sweden)

    Balanč Bojana D.

    2017-01-01

    Full Text Available The paper reports about the preparation and characterization of hydrogel particles containing liposomes loaded with resveratrol as an active compound. The materials used for preparation of the particles were chosen to be suitable for food industry. Different polymer concentrations affect particles shape, size, size distribution, as well as the release kinetics of resveratrol. The diameter of particles varied from 360 to 754 μm, while the narrow size distribution was observed for all types of particles. Release studies were performed in Franz diffusion cell and the results showed the prolonged release of resveratrol from all samples, but the sample with the highest content of polymer (2.5% w/w in particular stood out. The research provides useful information about liposomes containing active compound encapsulated in hydrogel matrices and offers the basis for its application in the food industry.

  13. Food-grade Pickering stabilisation of foams by in situ hydrophobisation of calcium carbonate particles

    NARCIS (Netherlands)

    Binks, Bernard P.; Muijlwijk, K.; Koman, Henriëtte; Poortinga, A.T.

    2017-01-01

    The aim of this study was to investigate the possibility of stabilising foam bubbles in water by adsorption of calcium carbonate (CaCO3) particles. Because CaCO3 is hydrophilic and not surface-active, particles were hydrophobised in situ with several emulsifiers. The used emulsifiers were food-grade

  14. Food-grade pickering stabilisation of foams by in situ hydrophobisation of calcium carbonate particles

    NARCIS (Netherlands)

    Binks, B.P.; Muijlwijk, K.; Koman, H.; Poortinga, A.T.

    2017-01-01

    The aim of this study was to investigate the possibility of stabilising foam bubbles in water by adsorption of calcium carbonate (CaCO3) particles. Because CaCO3 is hydrophilic and not surface-active, particles were hydrophobised in situ with several emulsifiers. The used emulsifiers were food-grade

  15. Nanometals - Status and perspective

    International Nuclear Information System (INIS)

    Faester, S.; Hansen, N.; Huang, X.; Juul Jensen, D.; Ralph, B.

    2012-01-01

    Nanometals and nanotechnology have over the years been covered in papers, books and conferences - also in many Risoe International Symposia, where the 30th in 2009 dealt solely with nanostructured metals. Since then, rapid progress has been made in synthesis, characterization and modeling, and it is timely to discuss status and perspective also with a view on applications in an international forum such as the Risoe Symposium. Both keynote and contributed papers address important current problems illustrating global research and development in this field. Examples are the development of new synthesis techniques followed by characterization and modeling of microstructures both in 2D and 3D now starting to bridge the micrometer scales. The vital area of mechanical behavior is addressed by the development of new testing techniques and a broad effort to characterize and model mechanical properties of metals strengthened by dislocations and twins. This research has now led to new understanding of both strengthening mechanisms and strengh structure relationships based on experiments in combination with analytical and numerical modeling. The holistic approach to research on nanometals demonstrated by these proceedings can guide both scientists and technologists in their future work also with the aim of introducing into society this new group of advanced materials. Such an effort is important, as science and technology today is significantly affected by politics of governments and international institutions, and therefore a new initiative in the pressent is to include a discussion of research and development in the area of nanometals i USA, China and Japan. (Author)

  16. Nanometals - Status and perspective

    Energy Technology Data Exchange (ETDEWEB)

    Faester, S.; Hansen, N.; Huang, X.; Juul Jensen, D.; Ralph, B. (eds.)

    2012-11-01

    Nanometals and nanotechnology have over the years been covered in papers, books and conferences - also in many Risoe International Symposia, where the 30th in 2009 dealt solely with nanostructured metals. Since then, rapid progress has been made in synthesis, characterization and modeling, and it is timely to discuss status and perspective also with a view on applications in an international forum such as the Risoe Symposium. Both keynote and contributed papers address important current problems illustrating global research and development in this field. Examples are the development of new synthesis techniques followed by characterization and modeling of microstructures both in 2D and 3D now starting to bridge the micrometer scales. The vital area of mechanical behavior is addressed by the development of new testing techniques and a broad effort to characterize and model mechanical properties of metals strengthened by dislocations and twins. This research has now led to new understanding of both strengthening mechanisms and strengh structure relationships based on experiments in combination with analytical and numerical modeling. The holistic approach to research on nanometals demonstrated by these proceedings can guide both scientists and technologists in their future work also with the aim of introducing into society this new group of advanced materials. Such an effort is important, as science and technology today is significantly affected by politics of governments and international institutions, and therefore a new initiative in the pressent is to include a discussion of research and development in the area of nanometals i USA, China and Japan. (Author)

  17. Fabrication of Al/Diamond Particles Functionally Graded Materials by Centrifugal Sintered-Casting Method

    International Nuclear Information System (INIS)

    Watanabe, Yoshimi; Shibuya, Masafumi; Sato, Hisashi

    2013-01-01

    The continuous graded structure of functionally graded materials (FGMs) can be created under a centrifugal force. Centrifugal sintered-casting (CSC) method, proposed by the authors, is one of the fabrication methods of FGM under centrifugal force. This method is a combination of the centrifugal sintering method and centrifugal casting method. In this study, Al/diamond particle FGM was fabricated by the proposed method.

  18. Physicochemical characterization of discrete weapons grade plutonium metal particles originating from the 1960 BOMARC incident

    Science.gov (United States)

    Bowen, James M.

    The goal of this research was to investigate the physicochemical properties of weapons grade plutonium particles originating from the 1960 BOMARC incident for the purpose of predicting their fate in the environment and to address radiation protection and nuclear security concerns. Methods were developed to locate and isolate the particles in order to characterize them. Physical, chemical, and radiological characterization was performed using a variety of techniques. And finally, the particles were subjected to a sequential extraction procedure, a series of increasingly aggressive reagents, to simulate an accelerated environmental exposure. A link between the morphology of the particles and their partitioning amongst environmental mechanisms was established.

  19. Pharmaceutical/food grade titanium dioxide particles are absorbed into the bloodstream of human volunteers.

    Science.gov (United States)

    Pele, Laetitia C; Thoree, Vinay; Bruggraber, Sylvaine F A; Koller, Dagmar; Thompson, Richard P H; Lomer, Miranda C; Powell, Jonathan J

    2015-09-02

    Exposure to persistent engineered nano and micro particles via the oral route is well established. Animal studies have demonstrated that, once ingested, a small proportion of such particles translocate from the gastrointestinal tract to other tissues. Exposure to titanium dioxide is widespread via the oral route, but only one study has provided indirect evidence (total titanium analyses) of absorption into the blood stream in humans. We sought to replicate these observations and to provide additional evidence for particulate uptake. Human volunteers with normal intestinal permeability were orally administered 100 mg pharmaceutical/food grade titanium dioxide. Blood samples were collected from 0.5 to 10 h post ingestion and analysed for the presence of reflectant bodies (particles) by dark field microscopy, and for total titanium by inductively coupled plasma mass spectrometry (ICP-MS). Blood film analyses implied early absorption of particles (2 h) with a peak maximum at 6 h following ingestion. The presence of these reflectant particles in blood roughly mirrored the levels of total titanium by ICP-MS, providing good evidence for the latter being a measure of whole particle (titanium dioxide) absorption. This study shows that a fraction of pharmaceutical/food grade titanium dioxide is absorbed systemically by humans following ingestion. It confirms that at least two routes of particle uptake may exist in the human gut- one proximal and one distal. Further work should quantify human exposure and uptake of such persistent particles.

  20. Comparison of particle morphology between commercial- and research-grade calcium hydroxide in endodontics.

    Science.gov (United States)

    Komabayashi, Takashi; Ahn, Chul; Spears, Robert; Zhu, Qiang

    2014-09-01

    Ca(OH)2 aqueous slurry is widely used as an inter-appointment antimicrobial dressing in root canal treatment. The aim of this study was to quantify the particle size and shape of commercial-grade UltraCal XS (UC) and to compare it with that of research-grade Ca(OH)2 (RG) using a flow particle image analyzer (FPIA). The morphology and penetration inside the dentin tubules of the UC and RG particles were examined using a scanning electron microscope (SEM). UC and RG (10 mg) were mixed with 15 mL of alcohol, and were sonicated. Five milliliters of the dispersion was subjected to FPIA, and particle length, width, perimeter and aspect ratio were analyzed. In addition, UC paste and RG aqueous slurry were agitated on dentin discs and were prepared for SEM examination. There were significant differences between UC and RG with regard to the frequency of different length groups (P < 0.0001). UC contained smaller particles than RG (P < 0.0001). Under SEM, the agitated UC and RG particles occluded the opening of dentin tubules and penetrated inside the dentin tubules. The size of UC particles is smaller than those of RG. Both UC and RG particles were able to penetrate into open dentin tubules.

  1. Nanometer Characterization/Manipulation Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Characterizes the nanometer scale of biological, chemical, physical, electronic, and mechanical properties of surfaces and thin films using scanning probe...

  2. Characteristics of dimethylaminium and trimethylaminium in atmospheric particles ranging from supermicron to nanometer sizes over eutrophic marginal seas of China and oligotrophic open oceans.

    Science.gov (United States)

    Yu, Peiran; Hu, Qingjing; Li, Kai; Zhu, Yujiao; Liu, Xiaohuan; Gao, Huiwang; Yao, Xiaohong

    2016-12-01

    In this study, we characterized dimethylaminium (DMA + ) and trimethylaminium (TMA + ) in size-segregated atmospheric particles during three cruise campaigns in the marginal seas of China and one cruise campaign mainly in the northwest Pacific Ocean (NWPO). An 14-stage nano-MOUDI sampler was utilized for sampling atmospheric particles ranging from 18μm to 0.010μm. Among the four cruise campaigns, the highest concentrations of DMA + and TMA + in PM 10 were observed over the South Yellow Sea (SYS) in August 2015, i.e., 0.76±0.12nmolm -3 for DMA + (average value±standard deviation) and 0.93±0.13nmolm -3 for TMA + . The lowest values were observed over the NWPO in April 2015, i.e., 0.28±0.16nmolm -3 for DMA + and 0.22±0.12nmolm -3 for TMA + . In general, size distributions of the two ions exhibited a bi-modal pattern, i.e., one mode at 0.01-0.1μm and the other at 0.1-1.8μm. The two ions' mode at 0.01-0.1μm was firstly observed. The mode was largely enhanced in samples collected over the SYS in August 2015, leading to high mole ratios of (DMA + +TMA + )/NH 4 + in PM 0.1 (0.4±0.8, median value±standard deviation) and the ions' concentrations in PM 0.1 accounting for ~10% and ~40% of their corresponding concentrations in PM 10 . This implied that (DMA + +TMA + ) likely played an important role in neutralizing acidic species in the smaller particles. Using SO 4 2- , NO 3 - and NH 4 + as references, we confirm that the elevated concentrations of DMA + and TMA + in the 0.01-0.1μm size range were probably real signals rather than sampling artifacts. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Acute and subchronic oral toxicity studies in rats with nanoscale and pigment grade titanium dioxide particles.

    Science.gov (United States)

    Warheit, D B; Brown, S C; Donner, E M

    2015-10-01

    Data generated using standardized testing protocols for toxicity studies generally provide reproducible and reliable results for establishing safe levels and formulating risk assessments. The findings of three OECD guideline-type oral toxicity studies of different duration in rats are summarized in this publication; each study evaluated different titanium dioxide (TiO2) particles of varying sizes and surface coatings. Moreover, each study finding demonstrated an absence of any TiO2 -related hazards. To briefly summarize the findings: 1) In a subchronic 90-day study (OECD TG 408), groups of young adult male and female rats were dosed with rutile-type, surface-coated pigment-grade TiO2 test particles (d50 = 145 nm - 21% nanoparticles by particle number criteria) by oral gavage for 90 days. The no-adverse-effect level (NOAEL) for both male and female rats in this study was 1000 mg/kg bw/day, the highest dose tested. The NOAEL was determined based on a lack of TiO2 particle-related adverse effects on any in-life, clinical pathology, or anatomic/microscopic pathology parameters; 2) In a 28-day repeated-dose oral toxicity study (OECD TG 407), groups of young adult male rats were administered daily doses of two rutile-type, uncoated, pigment-grade TiO2 test particles (d50 = 173 nm by number) by daily oral gavage at a dose of 24,000 mg/kg bw/day. There were no adverse effects measured during or following the end of the exposure period; and the NOAEL was determined to be 24,000 mg/kg bw/day; 3) In an acute oral toxicity study (OECD TG 425), female rats were administered a single oral exposure of surface-treated rutile/anatase nanoscale TiO2 particles (d50 = 73 nm by number) with doses up to 5000 mg/kg and evaluated over a 14-day post-exposure period. Under the conditions of this study, the oral LD50 for the test substance was >5000 mg/kg bw. In summary, the results from these three toxicity studies - each with different TiO2 particulate-types, demonstrated an absence of

  4. Modeling of solid oxide fuel cells with particle size and porosity grading in anode electrode

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L.; Flesner, R.; Kim, G.Y.; Chandra, A. [Department of Mechanical Engineering, Iowa State University, Ames, Iowa (United States)

    2012-02-15

    Solid oxide fuel cells (SOFCs) have the potential to meet the critical energy needs of our modern civilization and minimize the adverse environmental impacts from excessive energy consumption. They are highly efficient, clean, and can run on variety of fuel gases. However, little investigative focus has been put on optimal power output based on electrode microstructure. In this work, a complete electrode polarization model of SOFCs has been developed and utilized to analyze the performance of functionally graded anode with different particle size and porosity profiles. The model helps to understand the implications of varying the electrode microstructure from the polarization standpoint. The work identified conditions when grading can improve the cell performance and showed that grading is not always beneficial or necessary. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Cryochemistry of Nanometals

    OpenAIRE

    Shabatina, Tatyana I.; Sergeev, Gleb B.

    2010-01-01

    This survey of literature data and of the results obtained by the authors of the review shows that the methods of cryochemistry and cryonanochemistry make it possible to carry out and control self-assembling processes of metal atoms to form subnano- and nanosized aggregates, perform competitive chemical interactions of atoms, small clusters and nanosized metal particles with different organic and inorganic substances. At present time the effective approaches of cryochemistry are being develop...

  6. Characterization of food-grade titanium dioxide: the presence of nanosized particles.

    Science.gov (United States)

    Yang, Yu; Doudrick, Kyle; Bi, Xiangyu; Hristovski, Kiril; Herckes, Pierre; Westerhoff, Paul; Kaegi, Ralf

    2014-06-03

    Titanium dioxide (TiO2) is widely used in food products, which will eventually enter wastewater treatment plants and terrestrial or aquatic environments, yet little is known about the fraction of this TiO2 that is nanoscale, or the physical and chemical properties of TiO2 that influence its human and environmental fate or toxicity. Instead of analyzing TiO2 properties in complex food or environmental samples, we procured samples of food-grade TiO2 obtained from global food suppliers and then, using spectroscopic and other analytical techniques, quantified several parameters (elemental composition, crystal structure, size, and surface composition) that are reported to influence environmental fate and toxicity. Another sample of nano-TiO2 that is generally sold for catalytic applications (P25) and widely used in toxicity studies, was analyzed for comparison. Food-grade and P25 TiO2 are engineered products, frequently synthesized from purified titanium precursors, and not milled from bulk scale minerals. Nanosized materials were present in all of the food-grade TiO2 samples, and transmission electron microscopy showed that samples 1-5 contained 35, 23, 21, 17, and 19% of nanosized primary particles (average hydrodynamic diameter of >100 nm. Food-grade samples contained phosphorus (P), with concentrations ranging from 0.5 to 1.8 mg of P/g of TiO2. The phosphorus content of P25 was below inductively coupled plasma mass spectrometry detection limits. Presumably because of a P-based coating detected by X-ray photoelectron spectroscopy, the ζ potential of the food-grade TiO2 suspension in deionized water ranged from -10 to -45 mV around pH 7, and the iso-electric point for food-grade TiO2 (grade materials, and although the presence of amorphous TiO2 could not be ruled out, it is unlikely on the basis of Raman analysis. The food-grade TiO2 was solar photoactive. Cationic dyes adsorbed more readily to food-grade TiO2 than P25, indicating very different potentials for

  7. KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

    Energy Technology Data Exchange (ETDEWEB)

    STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

    2004-10-23

    While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

  8. A particle swarm-based algorithm for optimization of multi-layered and graded dental ceramics.

    Science.gov (United States)

    Askari, Ehsan; Flores, Paulo; Silva, Filipe

    2018-01-01

    The thermal residual stresses (TRSs) generated owing to the cooling down from the processing temperature in layered ceramic systems can lead to crack formation as well as influence the bending stress distribution and the strength of the structure. The purpose of this study is to minimize the thermal residual and bending stresses in dental ceramics to enhance their strength as well as to prevent the structure failure. Analytical parametric models are developed to evaluate thermal residual stresses in zirconia-porcelain multi-layered and graded discs and to simulate the piston-on-ring test. To identify optimal designs of zirconia-based dental restorations, a particle swarm optimizer is also developed. The thickness of each interlayer and compositional distribution are referred to as design variables. The effect of layers number constituting the interlayer between two based materials on the performance of graded prosthetic systems is also investigated. The developed methodology is validated against results available in literature and a finite element model constructed in the present study. Three different cases are considered to determine the optimal design of graded prosthesis based on minimizing (a) TRSs; (b) bending stresses; and (c) both TRS and bending stresses. It is demonstrated that each layer thickness and composition profile have important contributions into the resulting stress field and magnitude. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Impact of food grade and nano-TiO2 particles on a human intestinal community.

    Science.gov (United States)

    Dudefoi, William; Moniz, Kristy; Allen-Vercoe, Emma; Ropers, Marie-Hélène; Walker, Virginia K

    2017-08-01

    Titanium dioxide (TiO 2 ) nanoparticles (NPs) are used as an additive (E171 or INS171) in foods such as gum, candy and puddings. To address concerns about the potential hazardous effects of ingested NPs, the toxicity of these food-grade NPs was investigated with a defined model intestinal bacterial community. Each titania preparation (food-grade TiO 2 formulations, E171-1 and E171-6a) was tested at concentrations equivalent to those found in the human intestine after sampling 1-2 pieces of gum or candy (100-250 ppm). At the low concentrations used, neither the TiO 2 food additives nor control TiO 2 NPs had an impact on gas production and only a minor effect on fatty acids profiles (C16:00, C18:00, 15:1 w5c, 18:1 w9c and 18:1 w9c, p < 0.05). DNA profiles and phylogenetic distributions confirmed limited effects on the bacterial community, with a modest decrease in the relative abundance of the dominant Bacteroides ovatus in favor of Clostridium cocleatum (-13% and +14% respectively, p < 0.05). Such minor shifts in the treated consortia suggest that food grade and nano-TiO 2 particles do not have a major effect on human gut microbiota when tested in vitro at relevant low concentrations. However, the cumulative effects of chronic TiO 2 NP ingestion remain to be tested. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  10. A numerical test method of California bearing ratio on graded crushed rocks using particle flow modeling

    Directory of Open Access Journals (Sweden)

    Yingjun Jiang

    2015-04-01

    Full Text Available In order to better understand the mechanical properties of graded crushed rocks (GCRs and to optimize the relevant design, a numerical test method based on the particle flow modeling technique PFC2D is developed for the California bearing ratio (CBR test on GCRs. The effects of different testing conditions and micro-mechanical parameters used in the model on the CBR numerical results have been systematically studied. The reliability of the numerical technique is verified. The numerical results suggest that the influences of the loading rate and Poisson's ratio on the CBR numerical test results are not significant. As such, a loading rate of 1.0–3.0 mm/min, a piston diameter of 5 cm, a specimen height of 15 cm and a specimen diameter of 15 cm are adopted for the CBR numerical test. The numerical results reveal that the CBR values increase with the friction coefficient at the contact and shear modulus of the rocks, while the influence of Poisson's ratio on the CBR values is insignificant. The close agreement between the CBR numerical results and experimental results suggests that the numerical simulation of the CBR values is promising to help assess the mechanical properties of GCRs and to optimize the grading design. Besides, the numerical study can provide useful insights on the mesoscopic mechanism.

  11. Analog filters in nanometer CMOS

    CERN Document Server

    Uhrmann, Heimo; Zimmermann, Horst

    2014-01-01

    Starting from the basics of analog filters and the poor transistor characteristics in nanometer CMOS 10 high-performance analog filters developed by the authors in 120 nm and 65 nm CMOS are described extensively. Among them are gm-C filters, current-mode filters, and active filters for system-on-chip realization for Bluetooth, WCDMA, UWB, DVB-H, and LTE applications. For the active filters several operational amplifier designs are described. The book, furthermore, contains a review of the newest state of research on low-voltage low-power analog filters. To cover the topic of the book comprehensively, linearization issues and measurement methods for the characterization of advanced analog filters are introduced in addition. Numerous elaborate illustrations promote an easy comprehension. This book will be of value to engineers and researchers in industry as well as scientists and Ph.D students at universities. The book is also recommendable to graduate students specializing on nanoelectronics, microelectronics ...

  12. Passivation of pigment-grade TiO2 particles by nanothick atomic layer deposited SiO2 films

    International Nuclear Information System (INIS)

    King, David M; Liang Xinhua; Weimer, Alan W; Burton, Beau B; Akhtar, M Kamal

    2008-01-01

    Pigment-grade TiO 2 particles were passivated using nanothick insulating films fabricated by atomic layer deposition (ALD). Conformal SiO 2 and Al 2 O 3 layers were coated onto anatase and rutile powders in a fluidized bed reactor. SiO 2 films were deposited using tris-dimethylaminosilane (TDMAS) and H 2 O 2 at 500 deg. C. Trimethylaluminum and water were used as precursors for Al 2 O 3 ALD at 177 deg. C. The photocatalytic activity of anatase pigment-grade TiO 2 was decreased by 98% after the deposition of 2 nm SiO 2 films. H 2 SO 4 digest tests were performed to exhibit the pinhole-free nature of the coatings and the TiO 2 digest rate was 40 times faster for uncoated TiO 2 than SiO 2 coated over a 24 h period. Mass spectrometry was used to monitor reaction progress and allowed for dosing time optimization. These results demonstrate that the TDMAS-H 2 O 2 chemistry can deposit high quality, fully dense SiO 2 films on high radius of curvature substrates. Particle ALD is a viable passivation method for pigment-grade TiO 2 particles

  13. Imaging flow cytometry assays for quantifying pigment grade titanium dioxide particle internalization and interactions with immune cells in whole blood.

    Science.gov (United States)

    Hewitt, Rachel E; Vis, Bradley; Pele, Laetitia C; Faria, Nuno; Powell, Jonathan J

    2017-10-01

    Pigment grade titanium dioxide is composed of sub-micron sized particles, including a nanofraction, and is widely utilized in food, cosmetic, pharmaceutical, and biomedical industries. Oral exposure to pigment grade titanium dioxide results in at least some material entering the circulation in humans, although subsequent interactions with blood immune cells are unknown. Pigment grade titanium dioxide is employed for its strong light scattering properties, and this work exploited that attribute to determine whether single cell-particle associations could be determined in immune cells of human whole blood at "real life" concentrations. In vitro assays, initially using isolated peripheral blood mononuclear cells, identified titanium dioxide associated with the surface of, and within, immune cells by darkfield reflectance in imaging flow cytometry. This was confirmed at the population level by side scatter measurements using conventional flow cytometry. Next, it was demonstrated that imaging flow cytometry could quantify titanium dioxide particle-bearing cells, within the immune cell populations of fresh whole blood, down to titanium dioxide levels of 10 parts per billion, which is in the range anticipated for human blood following titanium dioxide ingestion. Moreover, surface association and internal localization of titanium dioxide particles could be discriminated in the assays. Overall, results showed that in addition to the anticipated activity of blood monocytes internalizing titanium dioxide particles, neutrophil internalization and cell membrane adhesion also occurred, the latter for both phagocytic and nonphagocytic cell types. What happens in vivo and whether this contributes to activation of one or more of these different cells types in blood merits further attention. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry.

  14. Preparation and Characterization of Some Nanometal Oxides Using Microwave Technique and Their Application to Cotton Fabrics

    Directory of Open Access Journals (Sweden)

    M. Gouda

    2015-01-01

    Full Text Available The objective of this paper is the synthesis of some nanometal oxides via microwave irradiation technique and their application to augment multifunctional properties of cotton fabric. Cotton fabrics containing nanometal oxides were prepared via a thiol-modification of cotton fabric samples and then dipped into the metal salt solutions precursors and transferred to the microwave oven. The surface morphology and quantitative analysis of the obtained modified cotton fabrics containing nanometal oxides were studied by scanning electron microscopy coupled with high energy dispersive X-ray (SEM-EDX. The shape and distribution of nanometal oxide inside the fabric samples were analyzed by transmission electron microscopy of cross-section fabric samples. The iron oxide nanoparticles had a nanosphere with particle size diameter 15–20 nm, copper oxide nanoparticles had a nanosphere with particle size diameter 25–30 nm, and cobalt oxide nanoparticles had a nanotube-like shape with a length of 100–150 nanometer and a diameter of ~58 nanometer, whereas the manganese oxide nanoparticles had a linear structure forming nanorods with a diameter of 50–55 nanometer and a length of 70–80 nanometers. Antibacterial activity was evaluated quantitatively against gram-positive bacteria such as Staphylococcus aureus and gram-negative bacteria such as Escherichia coli, UV-protection activity was analyzed using UV-DRS spectroscopy, and flame retardation of prepared fabric samples was evaluated according to the limiting oxygen index (LOI. Results revealed that the prepared fabric sample containing nanometal oxide possesses improved antibacterial, LOI, and UV-absorbing efficiency. Moreover, the metal oxide nanoparticles did not leach out the fabrics by washing even after 30 laundering washing cycles.

  15. Optoelectronic circuits in nanometer CMOS technology

    CERN Document Server

    Atef, Mohamed

    2016-01-01

    This book describes the newest implementations of integrated photodiodes fabricated in nanometer standard CMOS technologies. It also includes the required fundamentals, the state-of-the-art, and the design of high-performance laser drivers, transimpedance amplifiers, equalizers, and limiting amplifiers fabricated in nanometer CMOS technologies. This book shows the newest results for the performance of integrated optical receivers, laser drivers, modulator drivers and optical sensors in nanometer standard CMOS technologies. Nanometer CMOS technologies rapidly advanced, enabling the implementation of integrated optical receivers for high data rates of several Giga-bits per second and of high-pixel count optical imagers and sensors. In particular, low cost silicon CMOS optoelectronic integrated circuits became very attractive because they can be extensively applied to short-distance optical communications, such as local area network, chip-to-chip and board-to-board interconnects as well as to imaging and medical...

  16. The Effect Of Fine Particle Migration On Void Ratio Of Gap Graded Soil

    Directory of Open Access Journals (Sweden)

    Mayssa Salem Flayh

    2017-12-01

    Full Text Available Soil is exposed to the migration of fine particles in some cases because of some conditions including excavation and the presence of a level of groundwater which is equal to the level of soil in this case and because of the existence of this water leakage which would work on the migration of fine particles in the soil. This migration of fine particles will change the structure of the soil and change its properties. In this study we will know the change in the properties of the fouling soil due to the migration of fine particles and four types of soil. The first type does not contain fine particles and the second type the third and the fourth contains 10 20 30 granules respectively and tests were carried out for these soils Atterberg limits sieve analysis specific gravity shear resistance permeability modified Procter consolidation. A model was created to simulate the reality of soil exposed to excavations. Three levels were selected in the model to compare the results of each of the four soils under study. The total number of models 24 model through laboratory work obtained the initial and final voids ratio before and after aft the initial and final voids ratio er the particles migration. After these tests it was found that the migration of granules clearly affects the increase in the voids ratio.

  17. Nanometer scale materials - characterization and fabrication

    International Nuclear Information System (INIS)

    Murday, J.S.; Colton, R.J.; Rath, B.B.

    1993-01-01

    Materials and solid state scientists have made excellent progress in understanding material behavior in length scales from microns to meters. Below a micron, the lack of analytical prowess has been a deterrent. At the atomic scale, chemistry and atomic/molecular physics have also contributed significant understanding of matter. The maturity of these three communities, materials, solid state physics, atomic/molecular physics/chemistry, coupled with the development of analytical capability for nanometer-sized structures, promises to broaden our grasp of materials behavior into the last realm of unexplored size scales-nanometer. The motivation for this effort is driven both by the expectation of novel properties as well as by the potential solution to long standing technological issues. Critical scale lengths for many material properties fall in the nanometer range, examples include superconductor coherence lengths, electron inelastic mean free paths, electron wavelengths in solids, critical lengths for dislocation generation. Structures of nanometer size will undoubtedly show behavior unexpected from experience at the larger and smaller scales. Many technological problems such as adhesion, friction, corrosion, elasticity and fracture are believed to depend critically on nanometer scale phenomena. The millennia-old efforts to improve materials behavior have undoubtedly been slowed by our inability to 'observe' in this size range. (orig.)

  18. Functional nanometer-scale structures

    Science.gov (United States)

    Chan, Tsz On Mario

    Nanometer-scale structures have properties that are fundamentally different from their bulk counterparts. Much research effort has been devoted in the past decades to explore new fabrication techniques, model the physical properties of these structures, and construct functional devices. The ability to manipulate and control the structure of matter at the nanoscale has made many new classes of materials available for the study of fundamental physical processes and potential applications. The interplay between fabrication techniques and physical understanding of the nanostructures and processes has revolutionized the physical and material sciences, providing far superior properties in materials for novel applications that benefit society. This thesis consists of two major aspects of my graduate research in nano-scale materials. In the first part (Chapters 3--6), a comprehensive study on the nanostructures based on electrospinning and thermal treatment is presented. Electrospinning is a well-established method for producing high-aspect-ratio fibrous structures, with fiber diameter ranging from 1 nm--1 microm. A polymeric solution is typically used as a precursor in electrospinning. In our study, the functionality of the nanostructure relies on both the nanostructure and material constituents. Metallic ions containing precursors were added to the polymeric precursor following a sol-gel process to prepare the solution suitable for electrospinning. A typical electrospinning process produces as-spun fibers containing both polymer and metallic salt precursors. Subsequent thermal treatments of the as-spun fibers were carried out in various conditions to produce desired structures. In most cases, polymer in the solution and the as-spun fibers acted as a backbone for the structure formation during the subsequent heat treatment, and were thermally removed in the final stage. Polymers were also designed to react with the metallic ion precursors during heat treatment in some

  19. Response of consumer and research grade indoor air quality monitors to residential sources of fine particles.

    Science.gov (United States)

    Singer, B C; Delp, W W

    2018-04-23

    The ability to inexpensively monitor PM 2.5 to identify sources and enable controls would advance residential indoor air quality (IAQ) management. Consumer IAQ monitors incorporating low-cost optical particle sensors and connections with smart home platforms could provide this service if they reliably detect PM 2.5 in homes. In this study, particles from typical residential sources were generated in a 120 m 3 laboratory and time-concentration profiles were measured with 7 consumer monitors (2-3 units each), 2 research monitors (Thermo pDR-1500, MetOne BT-645), a Grimm Mini Wide-Range Aerosol Spectrometer (GRM), and a Tapered Element Oscillating Microbalance with Filter Dynamic Measurement System (FDMS), a Federal Equivalent Method for PM 2.5 . Sources included recreational combustion (candles, cigarettes, incense), cooking activities, an unfiltered ultrasonic humidifier, and dust. FDMS measurements, filter samples, and known densities were used to adjust the GRM to obtain time-resolved mass concentrations. Data from the research monitors and 4 of the consumer monitors-AirBeam, AirVisual, Foobot, Purple Air-were time correlated and within a factor of 2 of the estimated mass concentrations for most sources. All 7 of the consumer and both research monitors substantially under-reported or missed events for which the emitted mass was comprised of particles smaller than 0.3 μm diameter. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Microdosimetry in the nanometer region

    International Nuclear Information System (INIS)

    Biavati, M.H.; Rossi, H.H.; Goldhagen, P.

    1981-01-01

    Experimental work on the grid avalanche chamber has been continued. Several aspects of problems related to chamber operation, in particular the efficiency, have been investigated. These include a study of background and noise fluctuations with an effort to decrease and stabilize them, an effort to decrease light leaks, and an effort to determine if the light measured by the photomultiplier tube comes from the gas itself or from the scintillator. Work was also done on measuring coincidences between the solid state detector (which registers alpha particle traversals of the chamber) and the photomultiplier tube output, since all of the necessary electronics have finally been obtained. A study of the shape of equipotentials in the detector region was undertaken and also an apparatus was developed to apply thin coatings in a vacuum system

  1. Neuro-fuzzy GMDH based particle swarm optimization for prediction of scour depth at downstream of grade control structures

    Directory of Open Access Journals (Sweden)

    Mohammad Najafzadeh

    2015-03-01

    Full Text Available In the present study, neuro-fuzzy based-group method of data handling (NF-GMDH as an adaptive learning network was utilized to predict the maximum scour depth at the downstream of grade-control structures. The NF-GMDH network was developed using particle swarm optimization (PSO. Effective parameters on the scour depth include sediment size, geometry of weir, and flow characteristics in the upstream and downstream of structure. Training and testing of performances were carried out using non-dimensional variables. Datasets were divided into three series of dataset (DS. The testing results of performances were compared with the gene-expression programming (GEP, evolutionary polynomial regression (EPR model, and conventional techniques. The NF-GMDH-PSO network produced lower error of the scour depth prediction than those obtained using the other models. Also, the effective input parameter on the maximum scour depth was determined through a sensitivity analysis.

  2. [Clinical observation on nanometer acupoint mounting method for alleviation of myospasm complicated by spinal injury].

    Science.gov (United States)

    Zhang, Su-Jie; Si, Tong; Li, Zhi

    2008-11-01

    To observe clinical effect of nanometer acupoint mounting method for alleviation of myospasm complicated by spinal injury. Sixty cases were randomly divided into an observation group and a control group, 30 cases in each group. The observation group were treated by nanometer mounting at 4 Jiaji (EX-B 2) points each on both sides of the affected spine and Shenshu (BL 23), Shangliao (BL 31), Ciliao (BL 32), Yang-lingquan (GB 34), Xuanzhong (GB 39); and the control group by mounting zinc oxide sticking tablets at the above acupoints. The mounting was replaced once each two days, 7 times constituting one course. One week and one month after the end of 3 courses, their results were recorded, respectively. Before treatment, there was no significant difference between the two groups in grades of the myospasm degree (P > 0.05). One week after the end of treatment, 15 cases were grade I of myospasm, 9 cases were grade II, 5 cases were grade III and 1 case was grade IV in the observation group, and 1 cases grade I, 7 cases grade II, 14 cases grade III, 8 cases grade IV in the control group. Ridit analysis on the data indicated that there were significant differences before and after treatment in the myospasm degree (P mounting method is a new one for alleviation of myospasm complicated by spinal injury, with convenience, safety and no side effect.

  3. Glass ceramic ZERODUR enabling nanometer precision

    Science.gov (United States)

    Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Westerhoff, Thomas

    2014-03-01

    The IC Lithography roadmap foresees manufacturing of devices with critical dimension of digit nanometer asking for nanometer positioning accuracy requiring sub nanometer position measurement accuracy. The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion (CTE), the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR® to full fill the ever tighter CTE specification for wafer stepper components. In this paper we present the ZERODUR® Lithography Roadmap on the CTE metrology and tolerance. Additionally, simulation calculations based on a physical model are presented predicting the long term CTE behavior of ZERODUR® components to optimize dimensional stability of precision positioning devices. CTE data of several low thermal expansion materials are compared regarding their temperature dependence between - 50°C and + 100°C. ZERODUR® TAILORED 22°C is full filling the tight CTE tolerance of +/- 10 ppb / K within the broadest temperature interval compared to all other materials of this investigation. The data presented in this paper explicitly demonstrates the capability of ZERODUR® to enable the nanometer precision required for future generation of lithography equipment and processes.

  4. RF Circuit Design in Nanometer CMOS

    NARCIS (Netherlands)

    Nauta, Bram

    2007-01-01

    With CMOS technology entering the nanometer regime, the design of analog and RF circuits is complicated by low supply voltages, very non-linear (and nonquadratic) devices and large 1/f noise. At the same time, circuits are required to operate over increasingly wide bandwidths to implement modern

  5. Nanometer size wear debris generated from ultra high molecular weight polyethylene in vivo

    Czech Academy of Sciences Publication Activity Database

    Lapčíková, Monika; Šlouf, Miroslav; Dybal, Jiří; Zolotarevova, E.; Entlicher, G.; Pokorný, D.; Gallo, J.; Sosna, A.

    2009-01-01

    Roč. 266, 1-2 (2009), s. 349-355 ISSN 0043-1648 R&D Projects: GA MŠk 2B06096 Institutional research plan: CEZ:AV0Z40500505 Keywords : ultra high molecular weight polyethylene * nanometer size wear debris * morphology of wear particles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.771, year: 2009

  6. Vasomotor function in rat arteries after ex vivo and intragastric exposure to food-grade titanium dioxide and vegetable carbon particles

    DEFF Research Database (Denmark)

    Jensen, Ditte Marie; Christophersen, Daniel Vest; Sheykhzade, Majid

    2018-01-01

    -grade particle exposure on vasomotor function and systemic oxidative stress in an ex vivo study and intragastrically exposed rats.Methods: In an ex vivo study, aorta rings from naive Sprague-Dawley rats were exposed for 30 min to food-grade TiO2 (E171), benchmark TiO2 (Aeroxide P25), food-grade vegetable carbon...... (E153) or benchmark carbon black (Printex 90). Subsequently, the vasomotor function was assessed in wire myographs. In an in vivo study, lean Zucker rats were exposed intragastrically once a week for 10 weeks to vehicle, E171 or E153. Doses were comparable to human daily intake. Vasomotor function...... no differences between groups.Conclusion: Gastrointestinal tract exposure to E171 and E153 was associated with modest albeit statistically significant alterations in the vasocontraction and vasorelaxation responses. Direct particle exposure to aorta rings elicited a similar type of response. The vasomotor...

  7. Nanometer CMOS ICs from basics to ASICs

    CERN Document Server

    J M Veendrick, Harry

    2017-01-01

    This textbook provides a comprehensive, fully-updated introduction to the essentials of nanometer CMOS integrated circuits. It includes aspects of scaling to even beyond 12nm CMOS technologies and designs. It clearly describes the fundamental CMOS operating principles and presents substantial insight into the various aspects of design implementation and application. Coverage includes all associated disciplines of nanometer CMOS ICs, including physics, lithography, technology, design, memories, VLSI, power consumption, variability, reliability and signal integrity, testing, yield, failure analysis, packaging, scaling trends and road blocks. The text is based upon in-house Philips, NXP Semiconductors, Applied Materials, ASML, IMEC, ST-Ericsson, TSMC, etc., courseware, which, to date, has been completed by more than 4500 engineers working in a large variety of related disciplines: architecture, design, test, fabrication process, packaging, failure analysis and software.

  8. Theoretical study and simulation for a nanometer laser based on Gauss–Hermite source expansion

    International Nuclear Information System (INIS)

    Gu, Xiaowei

    2013-01-01

    Recently there has been worldwide interest in constructing a new generation of continuously tunable nanometer lasers for a wide range of scientific applications, including femtosecond science, biological molecules, nanoscience research fields, etc. The high brightness electron beam required by a short wavelength self-amplified spontaneous emission FEL can be reached only with accurate control of the beam dynamics in the facility. Numerical simulation codes are basic tools for designing new nanometer laser devices. We have developed a MATLAB quasi-one-dimensional code based on a reduced model for the FEL. The model uses an envelope description of the transverse dynamics of the laser beam and full longitudinal particle motion. We have optimized the LCLS facility parameters, then given the characteristics of the nanometer laser. (letter)

  9. Theoretical study and simulation for a nanometer laser based on Gauss-Hermite source expansion

    Science.gov (United States)

    Gu, Xiaowei

    2013-07-01

    Recently there has been worldwide interest in constructing a new generation of continuously tunable nanometer lasers for a wide range of scientific applications, including femtosecond science, biological molecules, nanoscience research fields, etc. The high brightness electron beam required by a short wavelength self-amplified spontaneous emission FEL can be reached only with accurate control of the beam dynamics in the facility. Numerical simulation codes are basic tools for designing new nanometer laser devices. We have developed a MATLAB quasi-one-dimensional code based on a reduced model for the FEL. The model uses an envelope description of the transverse dynamics of the laser beam and full longitudinal particle motion. We have optimized the LCLS facility parameters, then given the characteristics of the nanometer laser.

  10. The Effect of Crumb Rubber Particle Size to the Optimum Binder Content for Open Graded Friction Course

    Directory of Open Access Journals (Sweden)

    Mohd Rasdan Ibrahim

    2014-01-01

    Full Text Available The main objective of this paper is to investigate the relations of rubber size, rubber content, and binder content in determination of optimum binder content for open graded friction course (OGFC. Mix gradation type B as specified in Specification for Porous Asphalt produced by the Road Engineering Association of Malaysia (REAM was used in this study. Marshall specimens were prepared with four different sizes of rubber, namely, 20 mesh size [0.841 mm], 40 mesh [0.42 mm], 80 mesh [0.177 mm], and 100 mesh [0.149 mm] with different concentrations of rubberised bitumen (4%, 8%, and 12% and different percentages of binder content (4%–7%. The appropriate optimum binder content is then selected according to the results of the air voids, binder draindown, and abrasion loss test. Test results found that crumb rubber particle size can affect the optimum binder content for OGFC.

  11. Mixed Surfactant Template Method for Preparation of Nanometer Selenium

    Directory of Open Access Journals (Sweden)

    Zhi-Lin Li

    2009-01-01

    Full Text Available Selenium nanoparticles have been synthesized in an aqueous solution by using sodium dodecyl sulfate and polyvinyl alcohol as a soft template. The factors on synthesis, such as reaction time, concentration of reactants and ultrasonic irradiation were studied. The uniform stable selenium nanospheres were obstained in the conditions of 1.0 (mass fraction sodium dodecyl sulfate, 1.0 (mass fraction polyvinyl alcohol, n(Vc:n(H2SeO3=7:1 and 7 minutes after the initiation of the reaction at room temperature. The average particle size of selenium is about 30 nm. The product was characterized by UV and TEM. Finally the applications of the red element nanometer selenium in anti-older cosmetics are presented.

  12. Preparation, characterization and optical properties of Lanthanum-(nanometer MCM-41) composite materials

    International Nuclear Information System (INIS)

    Zhai, Q. Z.; Wang, P.

    2008-01-01

    Nanometer MCM-41 molecular sieve was prepared under a base condition by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as silica source by means of hydrothermal method. Lanthanum(III) was incorporated into the nanometer MCM-41 by a liquid phase grafting method. The prepared nano composite materials were characterized by means of powder X-ray diffraction, spectrophotometric analysis, Fourier transform infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid diffuse reflectance absorption spectra and luminescence. The powder X-ray diffraction studies show that the nanometer MCM-41 molecular sieve is successfully prepared. The highly ordered meso porous two-dimensional hexagonal channel structure and framework of the support MCM-41 is retained intact in the prepared composite material La-(nanometer MCM-41). The spectrophotometric analysis indicates that lanthanum exists in the prepared nano composite materials. The Fourier transform infrared spectra indicate that the framework of the MCM-41 molecular sieve still remains in the prepared nano composite materials and some framework vibration peaks show blue shifts relative to those of the MCM-41 molecular sieve. The low temperature nitrogen adsorption-desorption indicates that the guest locales in the channel of the molecular sieve. Compared with bulk lanthanum oxide, the guest in the channel of the molecular sieve has smaller particle size and shows a significant blue shift of optical absorption band in solid diffuse reflectance absorption spectra. The observed blue shift in the solid state diffuse reflectance absorption spectra of the lanthanum-(nanometer MCM-41) sample show the obvious stereoscopic confinement effect of the channel of the host on the guest, which further indicates the successful encapsulation of the guest in the host. The La-(nanometer MCM-41) sample shows luminescence

  13. Nanometer-sized emissions from municipal waste incinerators: A qualitative risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, David R., E-mail: david.r.johnson@ghd.com

    2016-12-15

    Municipal waste incinerators (MWI) are beneficial alternatives to landfills for waste management. A recent constituent of concern in emissions from these facilities is incidental nanometer-sized particles (INP{sub MWI}), i.e., particles smaller than 1 micrometer in size that may deposit in the deepest parts of the lungs, cross into the bloodstream, and affect different regions of the body. With limited data, the public may fear INP{sub MWI} due to uncertainty, which may affect public acceptance, regulatory permitting, and the increased lowering of air quality standards. Despite limited data, a qualitative risk assessment paradigm can be applied to determine the relative risk due to INP{sub MWI} emissions. This review compiles existing data on nanometer-sized particle generation by MWIs, emissions control technologies used at MWIs, emission releases into the atmosphere, human population exposure, and adverse health effects of nanometer-sized particles to generate a qualitative risk assessment and identify data gaps. The qualitative risk assessment conservatively concludes that INP{sub MWI} pose a low to moderate risk to individuals, primarily due to the lack of relevant toxicological data on INP{sub MWI} mixtures in ambient particulate matter.

  14. Secondary emission scintillation counter for microdosimetry at the nanometer level

    International Nuclear Information System (INIS)

    Goldhagen, P.

    1987-01-01

    The secondary emission scintillation (SES) counter is a device designed to count the positive ions of charged-particle tracks in gas volumes simulating sites in tissue with diameters of the order of 1 nanometer. Based on suggestions by H.H. Rossi and A.M. Kellerer, the basic idea of the device was developed by A. Kosiara, M. Biavati, and R.D. Colvett in the late 1970s. The device was substantially modified in 1982, but work on it was suspended before the new version could be tested, in order to devote full-time effort to rebuilding RARAF. Work resumed on the SES counter in 1986. A diagram of the prototype SES counter now being tested is shown. A weak electric field in the cylindrical collection region of the device drifts ions from a track to a small region (less than 1 mm) of high electric field where they are accelerated by several kilovolts onto a dynode, producing secondary electrons. The secondary electrons are then accelerated onto a plastic scintillator, and the resulting light is detected by a photomultiplier. The passage of a charged particle is established by a solid state detector, which triggers electronics detecting coincidences and measuring the timing and amplitude of pulses from the photomultiplier

  15. Electromagnetic fields of Nanometer electromagnetic waves and X-ray. New frontiers of electromagnetic wave engineering

    International Nuclear Information System (INIS)

    2009-01-01

    The investigating committee aimed at research on electromagnetic fields in functional devices and X-ray fibers for efficient coherent X-ray generation and their material science, high-precision manufacturing, X-ray microscope, application to medical and information communication technologies, such as interaction between material and nanometer electromagnetic waves of radiated light and X-ray, interaction between microwaves and particle beams, theory and design of high-frequency waveguides for resonator and accelerator, from January 2003 to December 2005. In this report, we describe our research results, in particular, on the topics of synchrotron radiation and Cherenkov radiation, Kyushu synchrotron light source and its technology, nanometer electromagnetic fields in optical region, process of interaction between evanescent waves and near-field light, orthogonal relation of electromagnetic fields including evanescent waves in dispersive dielectrics, optical amplification using electron beam, nanometer electromagnetic fields in focusing waveguide lens device with curved facets, electromagnetic fields in nanometer photonic crystal waveguide consisting of atoms, X-ray scattering and absorption I bio-material for image diagnosis. (author)

  16. Nanometer size field effect transistors for terahertz detectors

    International Nuclear Information System (INIS)

    Knap, W; Rumyantsev, S; Coquillat, D; Dyakonova, N; Teppe, F; Vitiello, M S; Tredicucci, A; Blin, S; Shur, M; Nagatsuma, T

    2013-01-01

    Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation. (paper)

  17. Evaluation of the effect of media velocity on filter efficiency and most penetrating particle size of nuclear grade high-efficiency particulate air filters.

    Science.gov (United States)

    Alderman, Steven L; Parsons, Michael S; Hogancamp, Kristina U; Waggoner, Charles A

    2008-11-01

    High-efficiency particulate air (HEPA) filters are widely used to control particulate matter emissions from processes that involve management or treatment of radioactive materials. Section FC of the American Society of Mechanical Engineers AG-1 Code on Nuclear Air and Gas Treatment currently restricts media velocity to a maximum of 2.5 cm/sec in any application where this standard is invoked. There is some desire to eliminate or increase this media velocity limit. A concern is that increasing media velocity will result in higher emissions of ultrafine particles; thus, it is unlikely that higher media velocities will be allowed without data to demonstrate the effect of media velocity on removal of ultrafine particles. In this study, the performance of nuclear grade HEPA filters, with respect to filter efficiency and most penetrating particle size, was evaluated as a function of media velocity. Deep-pleat nuclear grade HEPA filters (31 cm x 31 cm x 29 cm) were evaluated at media velocities ranging from 2.0 to 4.5 cm/sec using a potassium chloride aerosol challenge having a particle size distribution centered near the HEPA filter most penetrating particle size. Filters were challenged under two distinct mass loading rate regimes through the use of or exclusion of a 3 microm aerodynamic diameter cut point cyclone. Filter efficiency and most penetrating particle size measurements were made throughout the duration of filter testing. Filter efficiency measured at the onset of aerosol challenge was noted to decrease with increasing media velocity, with values ranging from 99.999 to 99.977%. The filter most penetrating particle size recorded at the onset of testing was noted to decrease slightly as media velocity was increased and was typically in the range of 110-130 nm. Although additional testing is needed, these findings indicate that filters operating at media velocities up to 4.5 cm/sec will meet or exceed current filter efficiency requirements. Additionally

  18. Nanometer scale thermometry in a living cell

    Science.gov (United States)

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

    2014-01-01

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

  19. NANOMETER PRECISION IN LARGE SURFACE PROFILOMETRY

    International Nuclear Information System (INIS)

    TAKACS, P.Z.

    1999-01-01

    The Long Trace Profiler (LTP) is in use at many synchrotron radiation (SR) laboratories throughout the world and by a number of manufacturers who specialize in fabricating grazing incidence mirrors for SR and x-ray telescope applications. Recent improvements in the design and operation of the LTP system have reduced the statistical error in slope profile measurement to the 1 standard deviation level of 0.3 microradian for 0.5 meter long mirrors. This corresponds to a height error on the order of 10-20 nanometers. This level of performance allows one to measure with confidence the absolute shape of large cylindrical aspheres and spheres that have kilometer radii of curvature in the axial direction. The LTP is versatile enough to make measurements of a mirror in the face up, sideways, and face down configurations. We will illustrate the versatility of the current version of the instrument, the LTP II, and present results from two new versions of the instrument: the in situ LTP (ISLTP) and the Vertical Scan LTP (VSLTP). Both of them are based on the penta prism LTP (ppLTP) principle that utilizes a stationary optical head and moving penta prism. The ISLTP is designed to measure the distortion of high heat load mirrors during actual operation in SR beam lines. The VSLTP is designed to measure the complete 3-dimensional shape of x-ray telescope cylinder mirrors and mandrels in a vertical configuration. Scans are done both in the axial direction and in the azimuthal direction

  20. Effects of WC Particle Size and Co Content on the Graded Structure in Functionally Gradient WC-Co Composites

    Directory of Open Access Journals (Sweden)

    Yuan Yigao

    2016-01-01

    Full Text Available Functionally gradient WC-Co composites having a Co depleted surface zone and not comprising the h phase can be manufactured via carburizing process. During carburizing, besides carburizing process parameters, the microstructural parameters of WC-Co materials, such as WC grain size and Co content, also have significant influences on the formation of Co gradient structure. In this study, the effects of WC particle size and Co content on the gradient structure within gradient hardmetals have been studied, based on a series of carburizing experiments of WC-Co materials with different WC particle sizes and cobalt contents. The results show that both the thickness and the amplitude of the gradients within gradient WC-Co materials increase with increasing initial WC particle size and Co content of WC-Co alloys. The reason for this finding is discussed.

  1. Displacement laser interferometry with sub-nanometer uncertainty

    NARCIS (Netherlands)

    Cosijns, S.J.A.G.

    2004-01-01

    Development in industry is asking for improved resolution and higher accuracy in mechanical measurement. Together with miniaturization the demand for sub nanometer uncertainty on dimensional metrology is increasing rapidly. Displacement laser interferometers are used widely as precision displacement

  2. Nanometer sized structures grown by pulsed laser deposition

    KAUST Repository

    ElZein, Basma

    2015-10-01

    Nanometer sized materials can be produced by exposing a target to a laser source to remove material from the target and deposit the removed material onto a surface of a substrate to grow a thin film in a vacuum chamber

  3. Optical properties of (nanometer MCM-41)-(malachite green) composite materials

    International Nuclear Information System (INIS)

    Li Xiaodong; Zhai Qingzhou; Zou Mingqiang

    2010-01-01

    Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman

  4. Numerical simulations of the melting behavior of bulk and nanometer-sized Cu systems

    International Nuclear Information System (INIS)

    Manai, G.; Delogu, F.

    2007-01-01

    Molecular dynamics simulations have been employed to investigate the melting mechanisms of four different Cu systems consisting of a surface-free crystalline bulk, a semi-crystal terminating with a free surface and two unsupported particles with a radius of about 4 and 8 nm, respectively. Starting from a relaxed configuration at 300 K, the systems were gradually heated up to the characteristic melting points. The surface-free bulk system underwent homogeneous melting at the limit of superheating, whereas the melting of the semi-crystal and of the nanometer-sized particles occurred with heterogeneous features. In these latter cases, the structural and energetic properties revealed a two-state character with a definite difference between disordered surface layers and bulk-like interiors. In addition, the melting point and the latent heat of fusion of the nanometer-sized particles were significantly depressed with respect to the ones of the semi-crystal, approximately corresponding to the equilibrium values. Pre-melting phenomena took place at the free surfaces at temperatures significantly below the melting point, determining the formation of a solid-liquid interface. Numerical findings indicate that in all the cases the onset of melting is connected with the proliferation and migration of lattice defects and that an intimate relationship exists between homogeneous and heterogeneous melting mechanisms

  5. Pro-inflammatory adjuvant properties of pigment-grade titanium dioxide particles are augmented by a genotype that potentiates interleukin 1β processing.

    Science.gov (United States)

    Riedle, Sebastian; Pele, Laetitia C; Otter, Don E; Hewitt, Rachel E; Singh, Harjinder; Roy, Nicole C; Powell, Jonathan J

    2017-12-08

    Pigment-grade titanium dioxide (TiO 2 ) particles are an additive to some foods (E171 on ingredients lists), toothpastes, and pharma-/nutraceuticals and are absorbed, to some extent, in the human intestinal tract. TiO 2 can act as a modest adjuvant in the secretion of the pro-inflammatory cytokine interleukin 1β (IL-1β) when triggered by common intestinal bacterial fragments, such as lipopolysaccharide (LPS) and/or peptidoglycan. Given the variance in human genotypes, which includes variance in genes related to IL-1β secretion, we investigated whether TiO 2 particles might, in fact, be more potent pro-inflammatory adjuvants in cells that are genetically susceptible to IL-1β-related inflammation. We studied bone marrow-derived macrophages from mice with a mutation in the nucleotide-binding oligomerisation domain-containing 2 gene (Nod2 m/m ), which exhibit heightened secretion of IL-1β in response to the peptidoglycan fragment muramyl dipeptide (MDP). To ensure relevance to human exposure, TiO 2 was food-grade anatase (119 ± 45 nm mean diameter ± standard deviation). We used a short 'pulse and chase' format: pulsing with LPS and chasing with TiO 2 +/- MDP or peptidoglycan. IL-1β secretion was not stimulated in LPS-pulsed bone marrow-derived macrophages, or by chasing with MDP, and only very modestly so by chasing with peptidoglycan. In all cases, however, IL-1β secretion was augmented by chasing with TiO 2 in a dose-dependent fashion (5-100 μg/mL). When co-administered with MDP or peptidoglycan, IL-1β secretion was further enhanced for the Nod2 m/m genotype. Tumour necrosis factor α was triggered by LPS priming, and more so for the Nod2 m/m genotype. This was enhanced by chasing with TiO 2 , MDP, or peptidoglycan, but there was no additive effect between the bacterial fragments and TiO 2 . Here, the doses of TiO 2 that augmented bacterial fragment-induced IL-1β secretion were relatively high. In vivo, however, selected intestinal cells appear

  6. POTENTIAL APPLICATION OF NANOMETALS IN ENVIRONMENTAL PROTECTION

    Directory of Open Access Journals (Sweden)

    Dagmara Malina

    2017-02-01

    Full Text Available In recent years, great interest in metallic nanoparticles has been observed, both because of their unlimited application possibilities, and also because of the unusual biological, chemical and physical features. It is expected that developments in nanotechnology will become the main promoter of scientific and technological innovations in the coming decades. Searching for a new and safe alternative to chemical pesticides, high hopes are associated with nanotechnology development. Particularly useful may be preparations containing nanoscale metal particles with strong antimicrobial properties. Importantly, safe and non-toxic for the plant components of biological origin may be used in nanoparticles synthesis. This article is a description of the potential applications of nanomaterials in environmental protection, which may become the basis for developing of new protection plant products with antimicrobial properties relative to plant pathogens and non-toxic to higher organisms.

  7. From nanometer aggregates to micrometer crystals

    DEFF Research Database (Denmark)

    Schultz, Logan Nicholas; Dideriksen, Knud; Lakshtanov, Leonid

    2014-01-01

    Grain size increases when crystals respond to dynamic equilibrium in a saturated solution. The pathway to coarsening is generally thought to be driven by Ostwald ripening, that is, simultaneous dissolution and reprecipitation, but models to describe Ostwald ripening neglect solid-solid interactions...... and crystal shapes. Grain coarsening of calcite, CaCO3, is relevant for biomineralization and commercial products and is an important process in diagenesis of sediments to rock during geological time. We investigated coarsening of pure, synthetic calcite powder of sub-micrometer diameter crystals and aged...... it in saturated solutions at 23, 100, and 200 °C for up to 261 days. Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area analysis showed rapid coarsening at 100 and 200 °C. Evidence of particle growth at 23 °C was not visible by SEM, but high resolution X-ray diffraction (XRD) data...

  8. Shearing Nanometer-Thick Confined Hydrocarbon Films: Friction and Adhesion

    DEFF Research Database (Denmark)

    Sivebæk, I. M.; Persson, B. N. J.

    2016-01-01

    We present molecular dynamics (MD) friction and adhesion calculations for nanometer-thick confined hydrocarbon films with molecular lengths 20, 100 and 1400 carbon atoms. We study the dependency of the frictional shear stress on the confining pressure and sliding speed. We present results...

  9. Some applications of nanometer scale structures for current and future X-ray space research

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Abdali, S; Frederiksen, P K

    1994-01-01

    Nanometer scale structures such as multilayers, gratings and natural crystals are playing an increasing role in spectroscopic applications for X-ray astrophysics. A few examples are briefly described as an introduction to current and planned applications pursued at the Danish Space Research...... Institute in collaboration with the FOM Institute for Plasma Physics, Nieuwegein, the Max-Planck-Institut für Extraterrestrische Physik, Aussenstelle Berlin, the Space Research Institute, Russian Academy of Sciences, the Smithsonian Astrophysical Observatory, Ovonics Synthetic Materials Company and Lawrence...... Livermore National Laboratory. These examples include : 1. the application of multilayered Si crystals for simultaneous spectroscopy in two energy bands one centred around the SK-emission near 2.45 keV and the other below the CK absorption edge at 0.284 keV; 2. the use of in-depth graded period multilayer...

  10. Spinel Li2CoTi3O8 nanometer obtained for application as pigment

    International Nuclear Information System (INIS)

    Costa de Camara, M. S.; Alves Pimentel, L.; Longo, E.; Nobrega Azevedo, L. da; Araujo Melo, D. M. de

    2016-01-01

    Pigments are used in ceramics, cosmetics, inks, and other applications widely materials. To this must be single and easily reproducible. Moreover, the pigments obtained in the nanoscale are more stable, reproducible and highlight color in small amounts compared with those obtained in micrometer scale. The mixed oxides with spinel structures AB 2 O 4 have important applications, including: pigments, refractories, catalytic and electronic ceramics. In this context, the aim of this work was the preparation of powder Li 2 CoTi 3 O 8 spinel phase with nanometer particle size of the polymeric precursor method (Pechini) and characterization by means of thermal analysis (TG/DTA) X-ray diffraction (XRD), refined by the Rietveld method, BET, transmission electron microscopy (TEM), Raman and colorimetric coordinates. The pigment was obtained by heat treatment of 400 degree centigrade to 1000 degree centigrade after pyrolysis at 300 degree centigrade/1 h for removing the organic material. Li 2 CoTi 3 O 8 desired spinel phase was obtained from 500 degree centigrade, and presenting stability nanometer to about 1.300 degree centigrade. Spinel green phase introduced at temperatures in the range of 400 degree centigrade and 500 degree centigrade, and 600 degree centigrade at temperatures between blue and 1000 degree centigrade. (Author)

  11. Analysis of nano-meter structure in Ti implanted polymers

    International Nuclear Information System (INIS)

    Zhou Gu; Wu Yuguang; Zhang Tonghe; Zhao Xinrong

    2001-01-01

    Polyethylene terephthalate (PET) is modified with Ti ion implantation to a dose of 1x10 17 to 2 x 10 17 cm -2 by using a metal vapor vacuum arc(MEVVA)source. Nano-meter structures in the implanted sample are observed by means of transmission electron microscope (TEM). The influence of ion dose on the structure is indicated. The results show that dense nano-meter phases are dispersed uniformly in the implanted layer. TEM cross section indicates that there is a three-layer structure in the implanted PET. It is found that a metallurgical surface is formed. Therefore the hardness, wear resistance and conductive properties of PET are improved after metal ion implantation. The mechanism of electrical conduction will be discussed

  12. Membranes for nanometer-scale mass fast transport

    Science.gov (United States)

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

    2011-10-18

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

  13. Imaging and Patterning on Nanometer Scale Using Coherent EUV Light

    International Nuclear Information System (INIS)

    Wachulak, P.W.; Fiedorowicz, H.; Bartnik, A.; Marconi, M.C.; Menoni, C.S.; Rocca, J.J.

    2010-01-01

    Extreme ultraviolet (EUV) covers wavelength range from about 5 nm to 50 nm. That is why EUV is especially applicable for imaging and patterning on nanometer scale length. In the paper periodic nanopatterning realized by interference lithography and high resolution holographic nanoimaging performed in a Gabor in-line scheme are presented. In the experiments a compact table top EUV laser was used. Preliminary studies on using a laser plasma EUV source for nanoimaging are presented as well. (author)

  14. Stochastic modelling in design of mechanical properties of nanometals

    International Nuclear Information System (INIS)

    Tengen, T.B.; Wejrzanowski, T.; Iwankiewicz, R.; Kurzydlowski, K.J.

    2010-01-01

    Polycrystalline nanometals are being fabricated through different processing routes and conditions. The consequence is that nanometals having the same mean grain size may have different grain size dispersion and, hence, may have different material properties. This has often led to conflicting reports from both theoretical and experimental findings about the evolutions of the mechanical properties of nanomaterials. The present paper employs stochastic model to study the impact of microstructure evolution during grain growth on the mechanical properties of polycrystalline nanometals. The stochastic model for grain growth and the stochastic model for changes in mechanical properties of nanomaterials are proposed. The model for the mechanical properties developed is tested on aluminium samples.Many salient features of the mechanical properties of the aluminium samples are revealed. The results show that the different mechanisms of grain growth impart different nature of response to the material mechanical properties. The conventional, homologous and anomalous temperature dependences of the yield stress have also been revealed to be due to different nature of interactions of the microstructures during evolution.

  15. Dimensional crossover in fluids under nanometer-scale confinement.

    Science.gov (United States)

    Das, Amit; Chakrabarti, J

    2012-05-01

    Several earlier studies have shown signatures of crossover in various static and dynamics properties of a confined fluid when the confining dimension decreases to about a nanometer. The density fluctuations govern the majority of such properties of a fluid. Here, we illustrate the crossover in density fluctuation in a confined fluid, to provide a generic understanding of confinement-induced crossover of fluid properties, using computer simulations. The crossover can be understood as a manifestation of changes in the long-wavelength behavior of fluctuation in density due to geometrical constraints. We further show that the confining potential significantly affects the crossover behavior.

  16. Structure and electrochemical properties of nanometer Cu substituted α-nickel hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Jie [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No. 100, Guangzhou 510006, Guangdong Province (China); Zhu, Yanjuan, E-mail: YanJuanZhu007@126.com [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No. 100, Guangzhou 510006, Guangdong Province (China); Zhang, Zhongju [Guangzhou Tiger Head Battery Group Co., Ltd., 568 Huangpu Road, Guangzhou 510655, Guangdong Province (China); Xu, Qingsheng; Zhao, Weiren [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No. 100, Guangzhou 510006, Guangdong Province (China); Chen, Jian [Instrumentation Analysis and Research Center, Sun Yat-sen University, Guangzhou 510275, Guangdong Province (China); Zhang, Wei; Han, Quanyong [School of Physics and Optoelectronic Engineering, Guangdong University of Technology, WaiHuan Xi Road, No. 100, Guangzhou 510006, Guangdong Province (China)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Cu substituted α-nickel hydroxide was prepared by ultrasonic assisted precipitation. ► The XRD peaks are anisotropic broadening. ► The electrode for 0.9 wt.% Cu has the highest capacity of 310 mAh/g at 0.2 C. -- Abstract: Nanometer Cu-substituted α-nickel hydroxide was synthesized by means of ultrasonic-assisted precipitation. Particle size distribution (PSD) measurement, X-ray diffraction (XRD), and high-resolution transmission electron microscope (HR-TEM) were used to characterize the physical properties of the synthesized samples. The results indicate that the average particle size of the samples is about 96–110 nm and the XRD diffraction peaks are anisotropic broadening. The crystal grains are mainly polycrystal structure with columnar or needle-like morphology, containing many defects. With increase of Cu content, the shape of primary particles transform from columnar to needle-like. The influences of doping amounts of Cu on the electrochemical performance were investigated through constant current charge/discharge and cyclic voltammetric measurements. The specific capacity increases initially and then decreases with increasing Cu-doping ratio, the electrode C containing 0.9 wt.% Cu shows the maximum discharge capacity of 310 mAh/g at 0.2 C, and it has the lowest charging voltage, higher discharge voltage plateau, better cycle performance and larger proton diffusion coefficient than the other electrodes.

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

    Science.gov (United States)

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

    2011-01-01

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

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

    International Nuclear Information System (INIS)

    Han, H.-S.; Chen, D.-R.; Pui, David Y.H.; Anderson, Bruce E.

    2000-01-01

    We have developed a fast-response nanometer aerosol size analyzer (nASA) that is capable of scanning 30 size channels between 3 and 100 nm in a total time of 3 s. The analyzer includes a bipolar charger (Po 210 ), an extended-length nanometer differential mobility analyzer (Nano-DMA), and an electrometer (TSI 3068). This combination of components provides particle size spectra at a scan rate of 0.1 s per channel free of uncertainties caused by response-time-induced smearing. The nASA thus offers a fast response for aerosol size distribution measurements in high-concentration conditions and also eliminates the need for applying a de-smearing algorithm to resulting data. In addition, because of its thermodynamically stable means of particle detection, the nASA is useful for applications requiring measurements over a broad range of sample pressures and temperatures. Indeed, experimental transfer functions determined for the extended-length Nano-DMA using the tandem differential mobility analyzer (TDMA) technique indicate the nASA provides good size resolution at pressures as low as 200 Torr. Also, as was demonstrated in tests to characterize the soot emissions from the J85-GE engine of a T-38 aircraft, the broad dynamic concentration range of the nASA makes it particularly suitable for studies of combustion or particle formation processes. Further details of the nASA performance as well as results from calibrations, laboratory tests and field applications are presented below

  19. Mesoporous TiO2 Micro-Nanometer Composite Structure: Synthesis, Optoelectric Properties, and Photocatalytic Selectivity

    Directory of Open Access Journals (Sweden)

    Kun Liu

    2012-01-01

    Full Text Available Mesoporous anatase TiO2 micro-nanometer composite structure was synthesized by solvothermal method at 180°C, followed by calcination at 400°C for 2 h. The as-prepared TiO2 was characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM, and Fourier transform infrared spectrum (FT-IR. The specific surface area and pore size distribution were obtained from N2 adsorption-desorption isotherm, and the optoelectric property of the mesoporous TiO2 was studied by UV-Vis absorption spectrum and surface photovoltage spectra (SPS. The photocatalytic activity was evaluated by photodegradation of sole rhodamine B (RhB and sole phenol aqueous solutions under simulated sunlight irradiation and compared with that of Degussa P-25 (P25 under the same conditions. The photodegradation preference of this mesoporous TiO2 was also investigated for an RhB-phenol mixed solution. The results show that the TiO2 composite structure consists of microspheres (∼0.5–2 μm in diameter and irregular aggregates (several hundred nanometers with rough surfaces and the average primary particle size is 10.2 nm. The photodegradation activities of this mesoporous TiO2 on both RhB and phenol solutions are higher than those of P25. Moreover, this as-prepared TiO2 exhibits photodegradation preference on RhB in the RhB-phenol mixture solution.

  20. Self-Assembly of Faceted Colloidal Particles

    NARCIS (Netherlands)

    Gantapara, A.P.

    2015-01-01

    A colloidal dispersion consists of insoluble microscopic particles that are suspended in a solvent. Typically, a colloid is a particle for which at least one of its dimension is within the size range of a nanometer to a micron. Due to collisions with much smaller solvent molecules, colloids perform

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

    Science.gov (United States)

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

    2016-10-01

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

  2. Nanometer CMOS Sigma-Delta Modulators for Software Defined Radio

    CERN Document Server

    Morgado, Alonso; Rosa, José M

    2012-01-01

    This book presents innovative solutions for the implementation of Sigma-Delta Modulation (SDM) based Analog-to-Digital Conversion (ADC), required for the next generation of wireless hand-held terminals. These devices will be based on the so-called multistandard transceiver chipsets, integrated in nanometer CMOS technologies. One of the most challenging and critical parts in such transceivers is the analog-digital interface, because of the assorted signal bandwidths and dynamic ranges that can be required to handle the A/D conversion for several operation modes.   This book describes new adaptive and reconfigurable SDM ADC topologies, circuit strategies and synthesis methods, specially suited for multi-standard wireless telecom systems and future Software-defined-radios (SDRs) integrated in nanoscale CMOS. It is a practical book, going from basic concepts to the frontiers of SDM architectures and circuit implementations, which are explained in a didactical and systematic way. It gives a comprehensive overview...

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

    Science.gov (United States)

    Flinn, John E.; Kelly, Thomas F.

    1999-01-01

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

  4. Sub-nanometer periodic nonlinearity error in absolute distance interferometers

    Science.gov (United States)

    Yang, Hongxing; Huang, Kaiqi; Hu, Pengcheng; Zhu, Pengfei; Tan, Jiubin; Fan, Zhigang

    2015-05-01

    Periodic nonlinearity which can result in error in nanometer scale has become a main problem limiting the absolute distance measurement accuracy. In order to eliminate this error, a new integrated interferometer with non-polarizing beam splitter is developed. This leads to disappearing of the frequency and/or polarization mixing. Furthermore, a strict requirement on the laser source polarization is highly reduced. By combining retro-reflector and angel prism, reference and measuring beams can be spatially separated, and therefore, their optical paths are not overlapped. So, the main cause of the periodic nonlinearity error, i.e., the frequency and/or polarization mixing and leakage of beam, is eliminated. Experimental results indicate that the periodic phase error is kept within 0.0018°.

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

    Science.gov (United States)

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

    1999-06-01

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

  6. Quantitative nanometer-scale mapping of dielectric tunability

    Energy Technology Data Exchange (ETDEWEB)

    Tselev, Alexander [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Klein, Andreas [Technische Univ. Darmstadt (Germany); Gassmann, Juergen [Technische Univ. Darmstadt (Germany); Jesse, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Li, Qian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kalinin, Sergei V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wisinger, Nina Balke [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-08-21

    Two scanning probe microscopy techniques—near-field scanning microwave microscopy (SMM) and piezoresponse force microscopy (PFM)—are used to characterize and image tunability in a thin (Ba,Sr)TiO3 film with nanometer scale spatial resolution. While sMIM allows direct probing of tunability by measurement of the change in the dielectric constant, in PFM, tunability can be extracted via electrostrictive response. The near-field microwave imaging and PFM provide similar information about dielectric tunability with PFM capable to deliver quantitative information on tunability with a higher spatial resolution close to 15 nm. This is the first time that information about the dielectric tunability is available on such length scales.

  7. Mechanically activated self-propagated high-temperature synthesis of nanometer-structured MgB2

    International Nuclear Information System (INIS)

    Radev, D.D.; Marinov, M.; Tumbalev, V.; Radev, I.; Konstantinov, L.

    2005-01-01

    Nanometer-sized MgB 2 was prepared via a two-step modification of the mechanically activated self-propagated high-temperature synthesis. The experimental conditions and some structural and phase characteristics of the synthesized product are reported. It is shown that a single-phase material can be prepared after 2 h of intense mechanical treatment of the starting magnesium and boron powders and a synthesis induced at a current-pulse density of 30 A cm -2 . The average size of MgB 2 particles synthesized in this way is 70-80 nm. It is also shown that using the same reagents and the 'classic' high-temperature interaction at 850 deg C with a protective atmosphere of pure Ar, mean particle size of the MgB 2 obtained is 50 μm

  8. First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

    CERN Document Server

    Walz, D

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor.

  9. First Beam Test of Nanometer Spot Size Monitor Using Laser Interferometry

    International Nuclear Information System (INIS)

    Walz, Dieter R

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry (Laser-Compton Spot Size Monitor) has been tested in FFTB beam line at SLAC. A low emittance beam of 46 GeV electrons, provided by the two-mile linear accelerator, was focused into nanometer spot in the FFTB line, and its transverse dimensions were precisely measured by the spot size monitor

  10. Characterization and observation of water-based nanofluids quench medium with carbon particle content variation

    Science.gov (United States)

    Yahya, S. S.; Harjanto, S.; Putra, W. N.; Ramahdita, G.; Kresnodrianto, Mahiswara, E. P.

    2018-05-01

    Recently, nanofluids have been widely used in heat treatment industries as quench medium with better quenching performance. The thermal conductivity of nanofluids is higher compared to conventional quench medium such as polymer, water, brine, and petroleum-based oil. This characteristic can be achieved by mixing high thermal conductivity particles in nanometer scale with a fluid as base. In this research, carbon powder and distilled water were used as nanoparticles and base respectively. The carbon source used in this research was laboratory grade carbon powder, and activated carbon as a cheaper alternative source. By adjusting the percentage of dispersed carbon particles, thermal conductivity of nanofluids could be controlled as needed. To obtain nanoscale carbon particles, planetary ball mill was used to grind laboratory-grade carbon and active carbon powder to further decrease its particle size. This milling method will provide nanoparticles with lower production cost. Milling speed and duration were set at 500 rpm and 15 hours. Scanning electron microscope (SEM) and Energy Dispersive X-Ray (EDX) were carried out respectively to determine the particle size, material identification, particle morphology. The carbon nanoparticle content in nanofluids quench mediums for this research were varied at 0.1, 0.3, and 0.5 % vol. Furthermore, these mediums were used to quench AISI 1045 carbon steel samples which had been annealed at 1000 °C. Hardness testing and metallography observation were then conducted to check the effect of different quench medium in steel samples. Preliminary characterizations showed that the carbon particle dimension after milling was hundreds of nanometers, or still in sub-micron range. Therefore, the milling process parameters are need to be optimized further. EDX observation in laboratory-grade carbon powder showed that the powder was pure carbon as expected for, but in activated carbon has some impurities. The nanofluid itself, however, was

  11. Research on long-range grating interferometry with nanometer resolution

    International Nuclear Information System (INIS)

    Chu, Xingchun; Zhao, Shanghong; Lü, Haibao

    2008-01-01

    Grating interferometry that features long range and nanometer resolution is presented. The optical system was established based on a single long metrology grating. The large fringe multiplication was achieved by properly selecting two high-order diffraction beams to form a fringe pattern. The fringe pattern collected by a linear array was first tailored to a few multiples of fringes in order to suppress the effect of the energy leakage on phase-extracting precision when the fast Fourier transform (FFT) algorithm was used to calculate its phase. Thus, the phase-extracting precision of a tailored fringe pattern by FFT was greatly improved. Based on this, a novel subdividing method, which exploited the time-shift property of FFT, was developed to subdivide the fringe with large multiple and high accuracy. Numerical results show that the system resolution reaches 1 nm. The experimental results obtained against a capacitive sensor in the sub-mm range show that the measurement precision of the system is less than 10 nm. (technical design note)

  12. Sub-nanometer glass surface dynamics induced by illumination

    International Nuclear Information System (INIS)

    Nguyen, Duc; Nienhaus, Lea; Haasch, Richard T.; Lyding, Joseph; Gruebele, Martin

    2015-01-01

    Illumination is known to induce stress and morphology changes in opaque glasses. Amorphous silicon carbide (a-SiC) has a smaller bandgap than the crystal. Thus, we were able to excite with 532 nm light a 1 μm amorphous surface layer on a SiC crystal while recording time-lapse movies of glass surface dynamics by scanning tunneling microscopy (STM). Photoexcitation of the a-SiC surface layer through the transparent crystal avoids heating the STM tip. Up to 6 × 10 4 s, long movies of surface dynamics with 40 s time resolution and sub-nanometer spatial resolution were obtained. Clusters of ca. 3-5 glass forming units diameter are seen to cooperatively hop between two states at the surface. Photoexcitation with green laser light recruits immobile clusters to hop, rather than increasing the rate at which already mobile clusters hop. No significant laser heating was observed. Thus, we favor an athermal mechanism whereby electronic excitation of a-SiC directly controls glassy surface dynamics. This mechanism is supported by an exciton migration-relaxation-thermal diffusion model. Individual clusters take ∼1 h to populate states differently after the light intensity has changed. We believe the surrounding matrix rearranges slowly when it is stressed by a change in laser intensity, and clusters serve as a diagnostic. Such cluster hopping and matrix rearrangement could underlie the microscopic mechanism of photoinduced aging of opaque glasses

  13. Sub-nanometer resolution XPS depth profiling: Sensing of atoms

    Energy Technology Data Exchange (ETDEWEB)

    Szklarczyk, Marek, E-mail: szklarcz@chem.uw.edu.pl [Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw (Poland); Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Macak, Karol; Roberts, Adam J. [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Takahashi, Kazuhiro [Kratos XPS Section, Shimadzu Corp., 380-1 Horiyamashita, Hadano, Kanagawa 259-1304 (Japan); Hutton, Simon [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Głaszczka, Rafał [Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Blomfield, Christopher [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom)

    2017-07-31

    Highlights: • Angle resolved photoelectron depth profiling of nano thin films. • Sensing atomic position in SAM films. • Detection of direction position of adsorbed molecules. - Abstract: The development of a method capable of distinguishing a single atom in a single molecule is important in many fields. The results reported herein demonstrate sub-nanometer resolution for angularly resolved X-ray photoelectron spectroscopy (ARXPS). This is made possible by the incorporation of a Maximum Entropy Method (MEM) model, which utilize density corrected electronic emission factors to the X-ray photoelectron spectroscopy (XPS) experimental results. In this paper we report on the comparison between experimental ARXPS results and reconstructed for both inorganic and organic thin film samples. Unexpected deviations between experimental data and calculated points are explained by the inaccuracy of the constants and standards used for the calculation, e.g. emission factors, scattering intensity and atomic density through the studied thickness. The positions of iron, nitrogen and fluorine atoms were determined in the molecules of the studied self-assembled monolayers. It has been shown that reconstruction of real spectroscopic data with 0.2 nm resolution is possible.

  14. Carbon nanotube transistors scaled to a 40-nanometer footprint.

    Science.gov (United States)

    Cao, Qing; Tersoff, Jerry; Farmer, Damon B; Zhu, Yu; Han, Shu-Jen

    2017-06-30

    The International Technology Roadmap for Semiconductors challenges the device research community to reduce the transistor footprint containing all components to 40 nanometers within the next decade. We report on a p-channel transistor scaled to such an extremely small dimension. Built on one semiconducting carbon nanotube, it occupies less than half the space of leading silicon technologies, while delivering a significantly higher pitch-normalized current density-above 0.9 milliampere per micrometer at a low supply voltage of 0.5 volts with a subthreshold swing of 85 millivolts per decade. Furthermore, we show transistors with the same small footprint built on actual high-density arrays of such nanotubes that deliver higher current than that of the best-competing silicon devices under the same overdrive, without any normalization. We achieve this using low-resistance end-bonded contacts, a high-purity semiconducting carbon nanotube source, and self-assembly to pack nanotubes into full surface-coverage aligned arrays. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  15. Sub-Nanometer Channels Embedded in Two-Dimensional Materials

    KAUST Repository

    Han, Yimo

    2017-07-31

    Two-dimensional (2D) materials are among the most promising candidates for next-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling1. Thus far, atomically-thin p-n junctions2-7, metal-semiconductor contacts8-10, and metal-insulator barriers11-13 have been demonstrated. While 2D materials achieve the thinnest possible devices, precise nanoscale control over the lateral dimensions are also necessary. Although external one-dimensional (1D) carbon nanotubes14 can be used to locally gate 2D materials, this adds a non-trivial third dimension, complicating device integration and flexibility. Here, we report the direct synthesis of sub-nanometer 1D MoS2 channels embedded within WSe2 monolayers, using a dislocation-catalyzed approach. The 1D channels have edges free of misfit dislocations and dangling bonds, forming a coherent interface with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Molecular dynamics (MD) simulations have identified other combinations of 2D materials that could form 1D channels. Density function theory (DFT) calculation predicts these 1D channels display type II band alignment needed for carrier confinement and charge separation to access the ultimate length scales necessary for future electronic applications.

  16. Bioavailability of elemental iron powders to rats is less than bakery-grade ferrous sulfate and predicted by iron solubility and particle surface area.

    Science.gov (United States)

    Swain, James H; Newman, Samuel M; Hunt, Janet R

    2003-11-01

    Foods are fortified with elemental forms of iron to reduce iron deficiency. However, the nutritional efficacy of current, commercially produced elemental iron powders has not been verified. We determined the bioavailability of six commercial elemental iron powders and examined how physicochemistry influences bioavailability. Relative biological value (RBV) of the iron powders was determined using a hemoglobin repletion/slope ratio method, treating iron-deficient rats with repletion diets fortified with graded quantities of iron powders, bakery-grade ferrous sulfate or no added iron. Iron powders were assessed physicochemically by measuring iron solubility in hydrochloric acid at pH 1.0 and 1.7, surface area by nitrogen gas adsorption and surface microstructure by electron microscopy. Bioavailability from the iron powders, based on absolute iron intake, was significantly less than from FeSO4 (100%; P Electrolytic (54%; A-131, U.S.) > Electrolytic (46%; Electrolytic Iron, India) > H-Reduced (42%; AC-325, U.S.) > Reduced (24%; ATOMET 95SP, Canada) > CO-Reduced (21%; RSI-325, Sweden). Solubility testing of the iron powders resulted in different relative rankings and better RBV predictability with increasing time at pH 1.7 (R2 = 0.65 at 150 min). The prediction was improved with less time and lower pH (R2 = 0.82, pH 1.0 at 30 min). Surface area, ranging from 90 to 370 m2/kg, was also highly predictive of RBV (R2 = 0.80). Bioavailability of iron powders is less than bakery-grade ferrous sulfate and varies up to three times among different commercial forms. Solubility at pH 1.0 and surface area were predictive of iron bioavailability in rats.

  17. Toxicological effects of nanometer titanium dioxide (nano-TiO2) on Chlamydomonas reinhardtii.

    Science.gov (United States)

    Chen, Lanzhou; Zhou, Lina; Liu, Yongding; Deng, Songqiang; Wu, Hao; Wang, Gaohong

    2012-10-01

    The toxicological effects of nanometer titanium dioxide (nano-TiO2) on a unicellular green alga Chlamydomonas reinhardtii were assessed by investigating the changes of the physiology and cyto-ultrastructure of this species under treatment. We found that nano-TiO2 inhibited photosynthetic efficiency and cell growth, but the content of chlorophyll a content in algae did not change, while carotenoid and chlorophyll b contents increased. Malondialdehyde (MDA) content reached maximum values after 8h exposure and then decreased to a moderately low level at 72 h. Electron microscopy images indicated that as concentrations of nano-TiO2 increased, a large number of C. reinhardtii cells were noted to be damaged: the number of chloroplasts declined, various other organelles were degraded, plasmolysis occurred, and TiO2 nanoparticles were found to be located inside cell wall and membrane. It was also noted that cell surface was surrounded by TiO2 particles, which could present an obstacle to the exchange of substances between the cell and its surrounding environment. To sum up, the effect of nano-TiO2 on C. reinhardtii included cell surface aggregation, photosynthesis inhibition, lipid peroxidation and new protein synthesis, while the response of C. reinhardtii to nano-TiO2 was a rapid process which occurs during 24 h after exposing and may relate to physiological stress system to mitigate damage. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Odeta; Ilton, Eugene S.; Bowden, Mark E.; Kovarik, Libor; Zhang, Xin; Kukkadapu, Ravi K.; Engelhard, Mark H.; Thompson, Christopher J.; Schaef, Herbert T.; McGrail, Bernard Peter; Rosso, Kevin M.; Loring, John S.

    2018-04-01

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

  19. Towards nanometer-spaced silicon contacts to proteins

    Science.gov (United States)

    Schukfeh, Muhammed I.; Sepunaru, Lior; Behr, Pascal; Li, Wenjie; Pecht, Israel; Sheves, Mordechai; Cahen, David; Tornow, Marc

    2016-03-01

    A vertical nanogap device (VND) structure comprising all-silicon contacts as electrodes for the investigation of electronic transport processes in bioelectronic systems is reported. Devices were fabricated from silicon-on-insulator substrates whose buried oxide (SiO2) layer of a few nanometers in thickness is embedded within two highly doped single crystalline silicon layers. Individual VNDs were fabricated by standard photolithography and a combination of anisotropic and selective wet etching techniques, resulting in p+ silicon contacts, vertically separated by 4 or 8 nm, depending on the chosen buried oxide thickness. The buried oxide was selectively recess-etched with buffered hydrofluoric acid, exposing a nanogap. For verification of the devices’ electrical functionality, gold nanoparticles were successfully trapped onto the nanogap electrodes’ edges using AC dielectrophoresis. Subsequently, the suitability of the VND structures for transport measurements on proteins was investigated by functionalizing the devices with cytochrome c protein from solution, thereby providing non-destructive, permanent semiconducting contacts to the proteins. Current-voltage measurements performed after protein deposition exhibited an increase in the junctions’ conductance of up to several orders of magnitude relative to that measured prior to cytochrome c immobilization. This increase in conductance was lost upon heating the functionalized device to above the protein’s denaturation temperature (80 °C). Thus, the VND junctions allow conductance measurements which reflect the averaged electronic transport through a large number of protein molecules, contacted in parallel with permanent contacts and, for the first time, in a symmetrical Si-protein-Si configuration.

  20. Towards nanometer-spaced silicon contacts to proteins

    International Nuclear Information System (INIS)

    Schukfeh, Muhammed I; Behr, Pascal; Tornow, Marc; Sepunaru, Lior; Li, Wenjie; Pecht, Israel; Sheves, Mordechai; Cahen, David

    2016-01-01

    A vertical nanogap device (VND) structure comprising all-silicon contacts as electrodes for the investigation of electronic transport processes in bioelectronic systems is reported. Devices were fabricated from silicon-on-insulator substrates whose buried oxide (SiO_2) layer of a few nanometers in thickness is embedded within two highly doped single crystalline silicon layers. Individual VNDs were fabricated by standard photolithography and a combination of anisotropic and selective wet etching techniques, resulting in p"+ silicon contacts, vertically separated by 4 or 8 nm, depending on the chosen buried oxide thickness. The buried oxide was selectively recess-etched with buffered hydrofluoric acid, exposing a nanogap. For verification of the devices’ electrical functionality, gold nanoparticles were successfully trapped onto the nanogap electrodes’ edges using AC dielectrophoresis. Subsequently, the suitability of the VND structures for transport measurements on proteins was investigated by functionalizing the devices with cytochrome c protein from solution, thereby providing non-destructive, permanent semiconducting contacts to the proteins. Current–voltage measurements performed after protein deposition exhibited an increase in the junctions’ conductance of up to several orders of magnitude relative to that measured prior to cytochrome c immobilization. This increase in conductance was lost upon heating the functionalized device to above the protein’s denaturation temperature (80 °C). Thus, the VND junctions allow conductance measurements which reflect the averaged electronic transport through a large number of protein molecules, contacted in parallel with permanent contacts and, for the first time, in a symmetrical Si–protein–Si configuration. (paper)

  1. Local mechanical spectroscopy with nanometer-scale lateral resolution

    Science.gov (United States)

    Oulevey, F.; Gremaud, G.; Sémoroz, A.; Kulik, A. J.; Burnham, N. A.; Dupas, E.; Gourdon, D.

    1998-05-01

    A new technique has been developed to probe the viscoelastic and anelastic properties of submicron phases of inhomogeneous materials. The measurement gives information related to the internal friction and to the variations of the dynamic modulus of nanometer-sized volumes. It is then the nanoscale equivalent to mechanical spectroscopy, a well-known macroscopic technique for materials studies, also sometimes called dynamic mechanical (thermal) analysis. The technique is based on a scanning force microscope, using the principle of scanning local-acceleration microscopy (SLAM), and allows the sample temperature to be changed. It is called variable-temperature SLAM, abbreviated T-SLAM. According to a recent proposition to systematize names of scanning probe microscope based methods, this technique should be included in the family of "mechanothermal analysis with scanning microscopy." It is suited for studying defect dynamics in nanomaterials and composites by locating the dissipative mechanisms in submicron phases. The primary and secondary relaxations, as well as the viscoplasticity, were observed in bulk PVC. The wide range of phenomena demonstrate the versatility of the technique. A still unexplained increase of the stiffness with increasing temperature was observed just below the glass transition. All of these observations, although their interpretation in terms of physical events is still tentative, are in agreement with global studies. This technique also permits one to image the variations of the local elasticity or of the local damping at a fixed temperature. This enables the study of, for instance, the homogeneity of phase transitions in multiphased materials, or of the interface morphologies and properties. As an illustration, the homogeneity of the glass transition temperature of PVC in a 50/50 wt % PVC/PB polymer blend has been demonstrated. Due to the small size of the probed volume, T-SLAM gives information on the mechanical properties of the near

  2. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.; Salem, H. G.; Yavari, A.; El Sayed, Tamer S.

    2013-01-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano

  3. [Electronic and structural properties of individual nanometer-size supported metallic clusters

    International Nuclear Information System (INIS)

    Reifenberger, R.

    1993-01-01

    This report summarizes the work performed under contract DOE-FCO2-84ER45162. During the past ten years, our study of electron emission from laser-illuminated field emission tips has taken on a broader scope by addressing problems of direct interest to those concerned with the unique physical and chemical properties of nanometer-size clusters. The work performed has demonstrated that much needed data can be obtained on individual nanometer-size clusters supported on a wide-variety of different substrates. The work was performed in collaboration with R.P. Andres in the School of Chemical Engineering at Purdue University. The Multiple Expansion Cluster Source developed by Andres and his students was essential for producing the nanometer-size clusters studied. The following report features a discussion of these results. This report provides a motivation for studying the properties of nanometer-size clusters and summarizes the results obtained

  4. [Electronic and structural properties of individual nanometer-size supported metallic clusters]. Final performance report

    Energy Technology Data Exchange (ETDEWEB)

    Reifenberger, R.

    1993-09-01

    This report summarizes the work performed under contract DOE-FCO2-84ER45162. During the past ten years, our study of electron emission from laser-illuminated field emission tips has taken on a broader scope by addressing problems of direct interest to those concerned with the unique physical and chemical properties of nanometer-size clusters. The work performed has demonstrated that much needed data can be obtained on individual nanometer-size clusters supported on a wide-variety of different substrates. The work was performed in collaboration with R.P. Andres in the School of Chemical Engineering at Purdue University. The Multiple Expansion Cluster Source developed by Andres and his students was essential for producing the nanometer-size clusters studied. The following report features a discussion of these results. This report provides a motivation for studying the properties of nanometer-size clusters and summarizes the results obtained.

  5. 25th Anniversary Article: Polymer-Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

    KAUST Repository

    Srivastava, Samanvaya; Schaefer, Jennifer L.; Yang, Zichao; Tu, Zhengyuan; Archer, Lynden A.

    2013-01-01

    . When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom-up synthesis strategies for understanding and controlling nanoparticle dispersion

  6. Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials

    Science.gov (United States)

    Grosse, Kyle Lane

    This work investigates nanometer-scale thermometry and thermal transport in new electronic devices to mitigate future electronic energy consumption. Nanometer-scale thermal transport is integral to electronic energy consumption and limits current electronic performance. New electronic devices are required to improve future electronic performance and energy consumption, but heat generation is not well understood in these new technologies. Thermal transport deviates significantly at the nanometer-scale from macroscopic systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy (SJEM), to measure nanometer-scale heat generation in new graphene and phase change memory (PCM) devices, which have potential to improve performance and energy consumption of future electronics. Nanometer-scale thermometry of chemical vapor deposition (CVD) grown graphene measured the heat generation at graphene wrinkles and grain boundaries (GBs). Graphene is an atomically-thin, two dimensional (2D) carbon material with promising applications in new electronic devices. Comparing measurements and predictions of CVD graphene heating predicted the resistivity, voltage drop, and temperature rise across the one dimensional (1D) GB defects. This work measured the nanometer-scale temperature rise of thin film Ge2Sb2Te5 (GST) based PCM due to Joule, thermoelectric, interface, and grain structure effects. PCM has potential to reduce energy consumption and improve performance of future electronic memory. A new nanometer-scale thermometry technique is developed for independent and direct observation of Joule and thermoelectric effects at the nanometer-scale, and the technique is demonstrated by SJEM measurements of GST devices. Uniform heating and GST properties are observed for

  7. Short-Period RF Undulator for a SASE Nanometer source

    International Nuclear Information System (INIS)

    Hirshfield, Jay L.

    2011-01-01

    Analysis is described towards development of a RF undulator with a period < 1 cm, an undulator parameter K of the order of unity, and a gap greater than 2.25 mm. The application for the undulator is for a SASE source to produce 1 nm wavelength radiation using a low energy electron beam in the range 1-2 GeV. Particle orbit calculations in a conventional standing-wave resonator configuration show that the presence of a co-propagating component of RF field can cause deleterious motion for the undulating electrons that can seriously degrade their radiation spectrum. To obviate this problem, resonator designs were devised in which only the counter-propagating field components interact with the particles. Two resonator configurations with the same undulator parameter K = 0.4 have been devised and are described in this report.

  8. Nano-metal oxides: Exposure and engineering control assessment.

    Science.gov (United States)

    Garcia, Alberto; Eastlake, Adrienne; Topmiller, Jennifer L; Sparks, Christopher; Martinez, Kenneth; Geraci, Charles L

    2017-09-01

    In January 2007, the National Institute for Occupational Safety and Health (NIOSH) conducted a field study to evaluate process specific emissions during the production of ENMs. This study was performed using the nanoparticle emission assessment technique (NEAT). During this study, it was determined that ENMs were released during production and cleaning of the process reactor. Airborne concentrations of silver, nickel, and iron were found both in the employee's personal breathing zone and area samples during reactor cleaning. At the completion of this initial survey, it was suggested that a flanged attachment be added to the local exhaust ventilation system.  NIOSH re-evaluated the facility in December 2011 to assess worker exposures following an increase in production rates. This study included a fully comprehensive emissions, exposure, and engineering control evaluation of the entire process. This study made use of the nanoparticle exposure assessment technique (NEAT 2.0). Data obtained from filter-based samples and direct reading instruments indicate that reactor cleanout increased the overall particle concentration in the immediate area. However, it does not appear that these concentrations affect areas outside of the production floor. As the distance between the reactor and the sample location increased, the observed particle number concentration decreased, creating a concentration gradient with respect to the reactor. The results of this study confirm that the flanged attachment on the local exhaust ventilation system served to decrease exposure potential.  Given the available toxicological data of the metals evaluated, caution is warranted. One should always keep in mind that occupational exposure levels were not developed specifically for nanoscale particles. With data suggesting that certain nanoparticles may be more toxic than the larger counterparts of the same material; employers should attempt to control emissions of these particles at the source

  9. Nanometer-scale anatomy of entire Stardust tracks

    Science.gov (United States)

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

    2011-07-01

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

  10. Atomistic Insight on the Charging Energetics in Sub-nanometer Pore Supercacitors

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Rui [ORNL; Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Feng, Guang [Clemson University

    2010-01-01

    Electrodes featuring sub-nanometer pores can significantly enhance the capacitance and energy density of supercapacitors. However, ions must pay an energy penalty to enter sub-nanometer pores as they have to shed part of their solvation shell. The magnitude of such energy penalty plays a key role in determining the accessibility and charging/discharging of these sub-nanometer pores. Here we report on the atomistic simulation of Na+ and Cl ions entering a polarizable slit pore with a width of 0.82 nm. We show that the free energy penalty for these ions to enter the pore is less than 14 kJ/mol for both Na+ and Cl ions. The surprisingly small energy penalty is caused by the van der Waals attractions between ion and pore walls, the image charge effects, the moderate (19-26%) de-hydration of the ions inside the pore, and the strengthened interactions between ions and their hydration water molecules in the sub-nanometer pore. The results provide strong impetus for further developing nanoporous electrodes featuring sub- nanometer pores.

  11. Structural peculiarities in magnetic small particles

    International Nuclear Information System (INIS)

    Haneda, K.; Morrish, A.H.

    1993-01-01

    Nanostructured magnetic materials, consisting of nanometer-sized crystallites, are currently a developing subject. Evidence has been accumulating that they possess properties that can differ substantially from those of bulk materials. This paper illustrates how Moessbauer spectroscopy can yield useful information on the structural peculiarities associated with these small particles. As illustrations, metallic iron and iron-oxide systems are considered in detail. The subjects discussed include: (1) Phase stabilities in small particles, (2) deformed or nonsymmetric atomic arrangements in small particles, and (3) peculiar magnetic structures or non-collinear spin arrangements in small magnetic oxide particles that are correlated with lower specific magnetizations as compared to the bulk values. (orig.)

  12. Flip-flop design in nanometer CMOS from high speed to low energy

    CERN Document Server

    Alioto, Massimo; Palumbo, Gaetano

    2015-01-01

    This book provides a unified treatment of Flip-Flop design and selection in nanometer CMOS VLSI systems. The design aspects related to the energy-delay tradeoff in Flip-Flops are discussed, including their energy-optimal selection according to the targeted application, and the detailed circuit design in nanometer CMOS VLSI systems. Design strategies are derived in a coherent framework that includes explicitly nanometer effects, including leakage, layout parasitics and process/voltage/temperature variations, as main advances over the existing body of work in the field. The related design tradeoffs are explored in a wide range of applications and the related energy-performance targets. A wide range of existing and recently proposed Flip-Flop topologies are discussed. Theoretical foundations are provided to set the stage for the derivation of design guidelines, and emphasis is given on practical aspects and consequences of the presented results. Analytical models and derivations are introduced when needed to gai...

  13. Nanometer-scale features in dolomite from Pennsylvanian rocks, Paradox Basin, Utah

    Science.gov (United States)

    Gournay, Jonas P.; Kirkland, Brenda L.; Folk, Robert L.; Lynch, F. Leo

    1999-07-01

    Scanning electron microscopy reveals an association between early dolomite in the Pennsylvanian Desert Creek (Paradox Fm.) and small (approximately 0.1 μm) nanometer-scale textures, termed `nannobacteria'. Three diagenetically distinct dolomites are present: early dolomite, limpid dolomite, and baroque dolomite. In this study, only the early dolomite contained nanometer-scale features. These textures occur as discrete balls and rods, clumps of balls, and chains of balls. Precipitation experiments demonstrate that these textures may be the result of precipitation in an organic-rich micro-environment. The presence of these nanometer-scale textures in Pennsylvanian rocks suggests that these early dolomites precipitated in organic-rich, bacterial environments.

  14. Imaging Action Potential in Single Mammalian Neurons by Tracking the Accompanying Sub-Nanometer Mechanical Motion.

    Science.gov (United States)

    Yang, Yunze; Liu, Xian-Wei; Wang, Hui; Yu, Hui; Guan, Yan; Wang, Shaopeng; Tao, Nongjian

    2018-03-28

    Action potentials in neurons have been studied traditionally by intracellular electrophysiological recordings and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with a sub-nanometer detection limit. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons by averaging the repeated action potential spikes. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2-0.4 nm. The work indicates that action potentials may be studied noninvasively in single mammalian neurons by label-free imaging of the accompanying sub-nanometer mechanical motion.

  15. Experiments of Nanometer Spot Size Monitor at FETB Using Laser Interferometry

    CERN Document Server

    Walz, D

    2003-01-01

    The nanometer spot size monitor based on the laser interferometry has been developed and installed in the final focus test beam (FFTB) line at SLAC. The beam experiments started in September 1993, the first fringe pattern from the monitor was observed in the beginning of April 1994, then the small vertical spot around 70 nm was observed in May 1994. The spot size monitor has been routinely used for tuning the beam optics in FFTB. Basic principle of this monitor has been well proved, and its high performance as a precise beam monitor in nanometer range has been demonstrated.

  16. Computer simulation of the 30-nanometer chromatin fiber.

    Science.gov (United States)

    Wedemann, Gero; Langowski, Jörg

    2002-06-01

    A new Monte Carlo model for the structure of chromatin is presented here. Based on our previous work on superhelical DNA and polynucleosomes, it reintegrates aspects of the "solenoid" and the "zig-zag" models. The DNA is modeled as a flexible elastic polymer chain, consisting of segments connected by elastic bending, torsional, and stretching springs. The electrostatic interaction between the DNA segments is described by the Debye-Hückel approximation. Nucleosome core particles are represented by oblate ellipsoids; their interaction potential has been parameterized by a comparison with data from liquid crystals of nucleosome solutions. DNA and chromatosomes are linked either at the surface of the chromatosome or through a rigid nucleosome stem. Equilibrium ensembles of 100-nucleosome chains at physiological ionic strength were generated by a Metropolis-Monte Carlo algorithm. For a DNA linked at the nucleosome stem and a nucleosome repeat of 200 bp, the simulated fiber diameter of 32 nm and the mass density of 6.1 nucleosomes per 11 nm fiber length are in excellent agreement with experimental values from the literature. The experimental value of the inclination of DNA and nucleosomes to the fiber axis could also be reproduced. Whereas the linker DNA connects chromatosomes on opposite sides of the fiber, the overall packing of the nucleosomes leads to a helical aspect of the structure. The persistence length of the simulated fibers is 265 nm. For more random fibers where the tilt angles between two nucleosomes are chosen according to a Gaussian distribution along the fiber, the persistence length decreases to 30 nm with increasing width of the distribution, whereas the other observable parameters such as the mass density remain unchanged. Polynucleosomes with repeat lengths of 212 bp also form fibers with the expected experimental properties. Systems with larger repeat length form fibers, but the mass density is significantly lower than the measured value. The

  17. Functional nanometers for hydrogen storage produced by ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Czujko, T. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering]|[Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies; Varin, R.A. [Waterloo Univ., ON (Canada). Dept. of Mechanical and Mechatronics Engineering; Wronski, Z.S. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Energy Technology Centre, Hydrogen Fuel Cells and Transportation; Zaranski, Z. [Military Univ. of Technology, Warsaw (Poland). Dept. of Advanced Materials and Technologies

    2008-07-01

    It is becoming increasingly important to switch to cleaner alternative energy carriers such as hydrogen, as environmental concerns over greenhouse gas emissions from the burning of fossil fuel increase. Specifically, there is a need for efficient on-board hydrogen storage technologies for vehicular applications. This paper discussed three different methods of hydrogen desorption temperature reduction and desorption kinetics of nanostructured hydrides. The first method was based on substantial hydride particle size refinement. The second method utilized catalytic effects of nanometric n-alumina (Al{sub 2}O{sub 3}), n-yttrium oxide powder (Y{sub 2}O{sub 3}) and n-nickel (Ni) additives. The third method was based on a composite of nanohydride mixtures. The composite approach was applied to the magnesium hydride (MgH{sub 2}) plus sodium tetrahydridoborate (NaBH{sub 4}) and lithium aluminum hydride (LiAlH{sub 4}) systems. The paper presented the effects of nanostructuring and nanocatalytic additives on Mg hydride desorption properties as well as a composite behaviour of nanostructured complex hydrides. It was concluded that milling of commercial MgH{sub 2} with the nano-oxide additives had a limited effect on improving the hydrogen storage properties. The addition of specialty Inco nanometric Ni reduced the hydrogen desorption temperature considerably. 28 refs., 1 tab., 9 figs.

  18. Green synthesis of noble nanometals (Au, Pt, Pd) using glycerol under microwave irradiation conditions

    Science.gov (United States)

    A newer application of glycerol in the field of nanomaterials synthesis has been developed from both the economic and environmental points of view. Glycerol can act as a reducing agent for the fabrication of noble nanometals, such as Au, Pt, and Pd, under microwave irradiation. T...

  19. A model based approach to reference-free straightness measurement at the Nanometer Comparator

    Science.gov (United States)

    Weichert, C.; Stavridis, M.; Walzel, M.; Elster, C.; Wiegmann, A.; Schulz, M.; Köning, R.; Flügge, J.; Tutsch, R.

    2009-06-01

    The Nanometer Comparator is the PTB reference length measuring machine for high precision calibrations of line scales and encoder systems. Up to now the Nanometer Comparator allows to measure the position of line structures in one dimension only. For high precision characterisations of masks, scales and incremental encoders, the measurement of the straightness of graduations is a requirement from emerging lithography techniques. Therefore the Nanometer Comparator will be equipped with an additional short range measurement system in the Y-direction, realized as a single path plane mirror interferometer and supposed to achieve sub-nm uncertainties. To compensate the topography of the Y-mirror, the Traceable Multi Sensor (TMS) method will be implemented to achieve a reference-free straightness measurement. Virtual experiments are used to estimate the lower accuracy limit and to determine the sensitive parameters. The virtual experiments contain the influence of the positioning devices, interferometer errors as well as non-perfect adjustment and fabrication of the machine geometry. The whole dynamic measurement process of the Nanometer Comparator including its influence on the TMS analysis, e.g. non-equally spaced measurement points, is simulated. We will present the results of these virtual experiments as well as the most relevant error sources for straightness measurement, incorporating the low uncertainties of the existing and planned measurement systems.

  20. Nanometer range closed-loop control of a stepper micro-motor for data storage

    NARCIS (Netherlands)

    Patrascu, M.; Stramigioli, Stefano; de Boer, Meint J.; Krijnen, Gijsbertus J.M.

    2007-01-01

    We present a nanometer range, closed-loop control study for MEMS stepper actuators. Although generically applicable to other types of stepper motors, the control design presented here was particularly intended for one dimensional shuffle actuators fabricated by surface micromachining technology. The

  1. Micrometer and nanometer-scale parallel patterning of ceramic and organic-inorganic hybrid materials

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Khan, Sajid; Göbel, Ole

    2010-01-01

    This review gives an overview of the progress made in recent years in the development of low-cost parallel patterning techniques for ceramic materials, silica, and organic–inorganic silsesquioxane-based hybrids from wet-chemical solutions and suspensions on the micrometer and nanometer-scale. The

  2. Characterization and H2-O2 reactivity of noble nano-metal tailored single wall nano-carbons

    International Nuclear Information System (INIS)

    K Kaneko; T Itoh; E Bekyarova; H Kanoh; S Utsumi; H Tanaka; M Yudasaka; S Iijima; S Iijima

    2005-01-01

    Full text of publication follows: Single wall carbon nano-tube (SWNT) and single wall carbon nano-horn (SWNH) have nano-spaces in their particles and the nano-spaces become open by oxidation. In particular, SWNH forms a unique colloidal structure which has micropores and meso-pores between the SWNH particles. Although non-treated SWNH colloids have quasi-one dimensional nano-pores [1], oxidized SWNH colloids have both of interstitial and internal nano-pores [2-5]. SWNH colloids show excellent supercritical methane storage ability [6], molecular sieving effect [7], and unique hydrogen adsorption characteristic [8]. Selective adsorptivity of SWNH colloids for H 2 and D 2 due to uncertainty principle of those molecules was shown [9-10]. As SWNH has no metallic impurities, we can study the effect of tailoring of metallic nano-particles on the surface activities of SWNH [11]. We tailored Pd or Pt nano-particles on SWNH and SWNH oxidized at 823 K (ox-SWNH) using poly[(2-oxo-pyrrolidine-1-yl)ethylene]. The oxidation of SWNH donates nano-scale windows to the single wall. The tailored metal amount was determined by TG analysis. TEM showed uniform dispersion of nano-metal particles of 2-3 nm in the diameter on SWNH. The nitrogen adsorption amount of SWNH oxidized decreases by tailoring, indicating that nano-particles are attached to the nano-scale windows. The electronic states of tailored metals were characterized by X-ray photoelectron spectroscopy. The surface activities of Pd tailored SWNH and ox-SWNH were examined for the reaction of hydrogen and oxygen near room temperature. The catalytic reactivities of Pd tailored SWNH and ox-SWNH were 4 times greater than that of Pd-dispersed activated carbon. The temperature dependence of the surface activity will be discussed with the relevance to the tube porosity. References [1] T. Ohba et al, J. Phys. Chem. In press. [2] S. Utsumi et al, J. Phys. Chem. In press. [3] C.- Min Yang, et al. Adv. Mater. In press. [4]C.M. Yang, J

  3. A scanning tunneling microscope with a scanning range from hundreds of micrometers down to nanometer resolution.

    Science.gov (United States)

    Kalkan, Fatih; Zaum, Christopher; Morgenstern, Karina

    2012-10-01

    A beetle type stage and a flexure scanning stage are combined to form a two stages scanning tunneling microscope (STM). It operates at room temperature in ultrahigh vacuum and is capable of scanning areas up to 300 μm × 450 μm down to resolution on the nanometer scale. This multi-scale STM has been designed and constructed in order to investigate prestructured metallic or semiconducting micro- and nano-structures in real space from atomic-sized structures up to the large-scale environment. The principle of the instrument is demonstrated on two different systems. Gallium nitride based micropillars demonstrate scan areas up to hundreds of micrometers; a Au(111) surface demonstrates nanometer resolution.

  4. Applied Study on Magnetic Nanometer Beads in Preparation of Genechip Samples

    Institute of Scientific and Technical Information of China (English)

    陈慧; 高华方; 谢欣; 马雪梅; 杨渝珍

    2004-01-01

    Summary: A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid-phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA-A PCR amplification system and a small HLA-A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe2O3) were set up.The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano-beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab-on-a-chip.

  5. Effect of nanometer scale surface roughness of titanium for osteoblast function

    Directory of Open Access Journals (Sweden)

    Satoshi Migita

    2017-02-01

    Full Text Available Surface roughness is an important property for metallic materials used in medical implants or other devices. The present study investigated the effects of surface roughness on cellular function, namely cell attachment, proliferation, and differentiation potential. Titanium (Ti discs, with a hundred nanometer- or nanometer-scale surface roughness (rough and smooth Ti surface, respectively were prepared by polishing with silicon carbide paper. MC3T3-E1 mouse osteoblast-like cells were cultured on the discs, and their attachment, spreading area, proliferation, and calcification were analyzed. Cells cultured on rough Ti discs showed reduced attachment, proliferation, and calcification ability suggesting that the surface inhibited osteoblast function. The findings can provide a basis for improving the biocompatibility of medical devices.

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

    Science.gov (United States)

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

    2015-08-21

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

  7. Nanometer-scale patterning of high-Tc superconductors for Josephson junction-based digital circuits

    International Nuclear Information System (INIS)

    Wendt, J.R.; Plut, T.A.; Corless, R.F.; Martens, J.S.; Berkowitz, S.; Char, K.; Johansson, M.; Hou, S.Y.; Phillips, J.M.

    1994-01-01

    A straightforward method for nanometer-scale patterning of high-T c superconductor thin films is discussed. The technique combines direct-write electron beam lithography with well-controlled aqueous etches and is applied to the fabrication of Josephson junction nanobridges in high-quality, epitaxial thin-film YBa 2 Cu 3 O 7 . We present the results of our studies of the dimensions, yield, uniformity, and mechanism of the junctions along with the performance of a representative digital circuit based on these junctions. Direct current junction parameter statistics measured at 77 K show critical currents of 27.5 μA±13% for a sample set of 220 junctions. The Josephson behavior of the nanobridge is believed to arise from the aggregation of oxygen vacancies in the nanometer-scale bridge

  8. A differential Michelson interferometer with orthogonal single frequency laser for nanometer displacement measurement

    International Nuclear Information System (INIS)

    Yan, Liping; Chen, Benyong; Wang, Bin

    2017-01-01

    A novel differential Michelson laser interferometer is proposed to eliminate the influence of environmental fluctuations for nanometer displacement measurement. This differential interferometer consists of two homodyne interferometers in which two orthogonal single frequency beams share common reference arm and partial measurement arm. By modulating the displacement of the common reference arm with a piezoelectric transducer, the common-mode displacement drift resulting from the environmental disturbances can be well suppressed and the measured displacement as differential-mode displacement signal is achieved. In addition, a phase difference compensation method is proposed for accurately determining the phase difference between interference signals by correcting the time interval according to the average speed in one cycle of interference signal. The nanometer displacement measurement experiments were performed to demonstrate the effectiveness and feasibility of the proposed interferometer and show that precision displacement measurement with standard deviation less than 1 nm has been achieved. (paper)

  9. Synthesis and characterization of nanometal-ordered mesoporous carbon composites as heterogeneous catalysts for electrooxidation of aniline

    International Nuclear Information System (INIS)

    Duan, Xiaoyue; Chen, Yawen; Liu, Xinyue; Chang, Limin

    2017-01-01

    Highlights: •NM-OMC catalysts were prepared for electrochemical oxidation of aniline. •The oxidation of aniline was studied with NM-OMC catalysts suspended in solution. •The Cu-OMC exhibited the highest catalytic activity for aniline degradation. •The mineralization current efficiency was improved by 2 times with Cu-OMC catalyst. •An electrochemical mineralization pathway of aniline was proposed. -- Abstract: The Cu, Co and Ni nanometal embedded ordered mesoporous carbons (NM-OMCs) were fabricated by a soft-template method using phenol/formaldehyde as carbon source and triblock copolymer F127 as template agent. The morphology, structure, surface physicochemical properties and pore structure of the NM-OMCs were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption isotherms. Their potential application to the electrocatalytic degradation of aniline was investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and ·OH radicals generation test. Furthermore, the electrochemical oxidation process of aniline was also investigated in the presence of the OMC-based catalyst particles suspended in a Na 2 SO 4 solution using a PbO 2 anode. Results revealed that the NM-OMCs inherited the ordered mesostructure of pristine OMC and the metal nanoparticles (Cu, Co or Ni) were embedded in the carbon framework. The Cu-OMC exhibited significantly higher catalytic activity than OMC and other NM-OMCs for the electrooxidation of aniline. In electrochemical oxidation process of aniline, nearly all of aniline could be degraded after 120 min of electrolysis with Cu-OMC particles as catalyst, while 89%, 92%, and 97% with OMC, Co-OMC and Ni-OMC catalysts, respectively, obviously higher than 76% of electrochemical oxidation without assistance of catalysts. After

  10. Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale

    International Nuclear Information System (INIS)

    Bolzon, B.

    2007-11-01

    CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

  11. Teachers' Grading Decision Making

    Science.gov (United States)

    Isnawati, Ida; Saukah, Ali

    2017-01-01

    This study investigated teachers' grading decision making, focusing on their beliefs underlying their grading decision making, their grading practices and assessment types, and factors they considered in grading decision making. Two teachers from two junior high schools applying different curriculum policies in grade reporting in Indonesian…

  12. Student Attitudes Toward Grades and Grading Practices.

    Science.gov (United States)

    Stallings, William M.; Leslie, Elwood K.

    The result of a study designed to assess student attitudes toward grading practices are discussed. Questionnaire responses of 3439 students in three institutions were tabulated. Responses were generally negative toward conventional grading systems. (MS)

  13. Electron beam driven disordering in small particles

    International Nuclear Information System (INIS)

    Vanfleet, R.R.; Mochel, J.

    1997-01-01

    Small metal particles in the range of a few nanometers in diameter are seen to progressively disorder when the 100 keV electron beam of a Scanning Transmission Electron Microscope (STEM) is held stationary on the particle. The diffraction pattern of the individual particle is seen to progress from an initial array of indexable diffraction spots to a mixture of diffraction spots and amorphous-like rings and finally to rings with no persistent diffraction spots. After the electron beam is removed, the particles will recrystallize after minutes or hours. Only particles below a critical size are seen to fully disorder. The authors have observed this in platinum, palladium, rhodium, and iridium and based on the model of disordering process believe it is a universal effect. It has also been observed with a platinum ruthenium alloy. They discuss the mechanism of this disordering and the structure of the resulting disordering particle for the case of platinum clusters

  14. Laser Pulse Heating of Spherical Metal Particles

    Directory of Open Access Journals (Sweden)

    Michael I. Tribelsky

    2011-12-01

    Full Text Available We consider the general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solution of the diffraction problem and solve the heat-transfer equation to determine the maximum temperature rise at the particle surface as a function of optical and thermometric parameters of the problem. Primary attention is paid to the case when the thermal diffusivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that, in this case, for any given duration of the laser pulse, the maximum temperature rise as a function of the particle size reaches a maximum at a certain finite size of the particle. We suggest simple approximate analytical expressions for this dependence, which cover the entire parameter range of the problem and agree well with direct numerical simulations.

  15. Particle Pollution

    Science.gov (United States)

    ... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution — ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

  16. Power calculation of grading device in desintegrator

    Science.gov (United States)

    Bogdanov, V. S.; Semikopenko, I. A.; Vavilov, D. V.

    2018-03-01

    This article describes the analytical method of measuring the secondary power consumption, necessitated by the installation of a grading device in the peripheral part of the grinding chamber in the desintegrator. There is a calculation model for defining the power input of the disintegrator increased by the extra power demand, required to rotate the grading device and to grind the material in the area between the external row of hammers and the grading device. The work has determined the inertia moments of a cylindrical section of the grading device with armour plates. The processing capacity of the grading device is adjusted to the conveying capacity of the auger feeder. The grading device enables one to increase the concentration of particles in the peripheral part of the grinding chamber and the amount of interaction between particles and armour plates as well as the number of colliding particles. The perforated sections provide the output of the ground material with the proper size granules, which together with the effects of armour plates, improves the efficiency of grinding. The power demand to rotate the grading device does not exceed the admissible value.

  17. Dusty-Plasma Particle Accelerator

    Science.gov (United States)

    Foster, John E.

    2005-01-01

    A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

  18. The voltammetric responses of nanometer-sized electrodes in weakly supported electrolyte: A theoretical study

    International Nuclear Information System (INIS)

    Liu Yuwen; Zhang Qianfan; Chen Shengli

    2010-01-01

    The effect of the supporting electrolyte concentration on the interfacial profiles and voltammetric responses of nanometer-sized disk electrodes have been investigated theoretically by combining the Poisson-Nernst-Planck (PNP) theory and Butler-Volmer (BV) equation. The PNP-theory is used to treat the nonlinear couplings of electric field, concentration field and dielectric field at electrochemical interface without the electroneutrality assumption that has been long adopted in various voltammetric theories for macro/microelectrodes. The BV equation is modified by using the Frumkin correction to account for the effect of the diffuse double layer potential on interfacial electron-transfer (ET) rate and by including a distance-dependent ET probability in the expression of rate constant to describe the radial heterogeneity of the ET rate constant at nanometer-sized disk electrodes. The computed voltammetric responses for disk electrodes larger than 200 nm in radii in the absence of the excess of the supporting electrolyte using the present theoretical scheme show reasonable agreements with the predications of the conventional microelectrode voltammetric theory which uses the combined Nernst-Planck equation and electroneutrality equation to describe the mixed electromigration-diffusion mass transport without including the possible effects of the diffuse double layer (Amatore et al. ). For electrodes smaller than 200 nm, however, the voltammetric responses predicated by the present theory exhibit significant deviation from the microelectrode theory. It is shown that the deviations are mainly resulted from the overlap between the diffuse double layer and the concentration depletion layer (CDL) at nanoscale electrochemical interfaces in weakly supported media, which will result in the invalidation of the electroneutrality condition in CDL, and from the radial inhomogeneity of ET probability at nanometer-sized disk electrodes.

  19. The voltammetric responses of nanometer-sized electrodes in weakly supported electrolyte: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yuwen; Zhang Qianfan [Hubei Electrochemical Power Sources Key Laboratory, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072 (China); Chen Shengli, E-mail: slchen@whu.edu.c [Hubei Electrochemical Power Sources Key Laboratory, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2010-11-30

    The effect of the supporting electrolyte concentration on the interfacial profiles and voltammetric responses of nanometer-sized disk electrodes have been investigated theoretically by combining the Poisson-Nernst-Planck (PNP) theory and Butler-Volmer (BV) equation. The PNP-theory is used to treat the nonlinear couplings of electric field, concentration field and dielectric field at electrochemical interface without the electroneutrality assumption that has been long adopted in various voltammetric theories for macro/microelectrodes. The BV equation is modified by using the Frumkin correction to account for the effect of the diffuse double layer potential on interfacial electron-transfer (ET) rate and by including a distance-dependent ET probability in the expression of rate constant to describe the radial heterogeneity of the ET rate constant at nanometer-sized disk electrodes. The computed voltammetric responses for disk electrodes larger than 200 nm in radii in the absence of the excess of the supporting electrolyte using the present theoretical scheme show reasonable agreements with the predications of the conventional microelectrode voltammetric theory which uses the combined Nernst-Planck equation and electroneutrality equation to describe the mixed electromigration-diffusion mass transport without including the possible effects of the diffuse double layer (Amatore et al. ). For electrodes smaller than 200 nm, however, the voltammetric responses predicated by the present theory exhibit significant deviation from the microelectrode theory. It is shown that the deviations are mainly resulted from the overlap between the diffuse double layer and the concentration depletion layer (CDL) at nanoscale electrochemical interfaces in weakly supported media, which will result in the invalidation of the electroneutrality condition in CDL, and from the radial inhomogeneity of ET probability at nanometer-sized disk electrodes.

  20. Simulation of Electrical Discharge Initiated by a Nanometer-Sized Probe in Atmospheric Conditions

    International Nuclear Information System (INIS)

    Chen Ran; Chen Chilai; Liu Youjiang; Wang Huanqin; Kong Deyi; Ma Yuan; Cada Michael; Brugger Jürgen

    2013-01-01

    In this paper, a two-dimensional nanometer scale tip-plate discharge model has been employed to study nanoscale electrical discharge in atmospheric conditions. The field strength distributions in a nanometer scale tip-to-plate electrode arrangement were calculated using the finite element analysis (FEA) method, and the influences of applied voltage amplitude and frequency as well as gas gap distance on the variation of effective discharge range (EDR) on the plate were also investigated and discussed. The simulation results show that the probe with a wide tip will cause a larger effective discharge range on the plate; the field strength in the gap is notably higher than that induced by the sharp tip probe; the effective discharge range will increase linearly with the rise of excitation voltage, and decrease nonlinearly with the rise of gap length. In addition, probe dimension, especially the width/height ratio, affects the effective discharge range in different manners. With the width/height ratio rising from 1:1 to 1:10, the effective discharge range will maintain stable when the excitation voltage is around 50 V. This will increase when the excitation voltage gets higher and decrease as the excitation voltage gets lower. Furthermore, when the gap length is 5 nm and the excitation voltage is below 20 V, the diameter of EDR in our simulation is about 150 nm, which is consistent with the experiment results reported by other research groups. Our work provides a preliminary understanding of nanometer scale discharges and establishes a predictive structure-behavior relationship

  1. Grinding model and material removal mechanism of medical nanometer zirconia ceramics.

    Science.gov (United States)

    Zhang, Dongkun; Li, Changhe; Jia, Dongzhou; Wang, Sheng; Li, Runze; Qi, Xiaoxiao

    2014-01-01

    Many patents have been devoted to developing medical nanometer zirconia ceramic grinding techniques that can significantly improve both workpiece surface integrity and grinding quality. Among these patents is a process for preparing ceramic dental implants with a surface for improving osseo-integration by sand abrasive finishing under a jet pressure of 1.5 bar to 8.0 bar and with a grain size of 30 µm to 250 µm. Compared with other materials, nano-zirconia ceramics exhibit unmatched biomedical performance and excellent mechanical properties as medical bone tissue and dentures. The removal mechanism of nano-zirconia materials includes brittle fracture and plastic removal. Brittle fracture involves crack formation, extension, peeling, and chipping to completely remove debris. Plastic removal is similar to chip formation in metal grinding, including rubbing, ploughing, and the formation of grinding debris. The materials are removed in shearing and chipping. During brittle fracture, the grinding-led transverse and radial extension of cracks further generate local peeling of blocks of the material. In material peeling and removal, the mechanical strength and surface quality of the workpiece are also greatly reduced because of crack extension. When grinding occurs in the plastic region, plastic removal is performed, and surface grinding does not generate grinding fissures and surface fracture, producing clinically satisfactory grinding quality. With certain grinding conditions, medical nanometer zirconia ceramics can be removed through plastic flow in ductile regime. In this study, we analyzed the critical conditions for the transfer of brittle and plastic removal in nano-zirconia ceramic grinding as well as the high-quality surface grinding of medical nanometer zirconia ceramics by ELID grinding.

  2. Self-assembled metallic nanoparticle template — a new approach of surface nanostructuring at nanometer scale

    Directory of Open Access Journals (Sweden)

    A. Taleb

    2017-09-01

    Full Text Available In the present work, the formation of silver and copper nanostructures on highly oriented pyrolytic graphite (HOPG modified with self-assembled gold nanoparticles (Au NPs is demonstrated. Surface patterning with nanometer resolution was achieved. Different methods such as field emission scanning electron microscopy (FEGSEM, energy dispersive spectrometry (EDS and X-ray photoelectron spectroscopy (XPS were used to illustrate a selective deposition of silver and copper on Au NPs. The mechanism of silver and copper ions reduction on Au NP with n-dodecanethiol coating is discussed.

  3. Hybrid approaches to nanometer-scale patterning: Exploiting tailored intermolecular interactions

    International Nuclear Information System (INIS)

    Mullen, Thomas J.; Srinivasan, Charan; Shuster, Mitchell J.; Horn, Mark W.; Andrews, Anne M.; Weiss, Paul S.

    2008-01-01

    In this perspective, we explore hybrid approaches to nanometer-scale patterning, where the precision of molecular self-assembly is combined with the sophistication and fidelity of lithography. Two areas - improving existing lithographic techniques through self-assembly and fabricating chemically patterned surfaces - will be discussed in terms of their advantages, limitations, applications, and future outlook. The creation of such chemical patterns enables new capabilities, including the assembly of biospecific surfaces to be recognized by, and to capture analytes from, complex mixtures. Finally, we speculate on the potential impact and upcoming challenges of these hybrid strategies.

  4. The nature of the Fe-graphene interface at the nanometer level

    Energy Technology Data Exchange (ETDEWEB)

    Cattelan, Mattia, E-mail: mattia.cattelan.1@studenti.unipd.it; Artiglia, Luca; Favaro, Marco; Agnoli, Stefano, E-mail: mattia.cattelan.1@studenti.unipd.it; Granozzi, Gaetano [Department of Chemical Sciences, University of Padova, via Marzolo 1, 35135, Padova (Italy); Peng, Guowen; Roling, Luke T.; Mavrikakis, Manos [Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Cavaliere, Emanuele; Gavioli, Luca [Interdisciplinary Laboratories for Advanced Materials Physics (i-LAMP) and Dipartimento di Matematica e Fisica, Università Cattolica, via dei Musei 41, I-25121 Brescia (Italy); Barinov, Alexey [Sincrotrone Trieste S.C.p.A., Area Science Park-Basovizza, Strada Statale 14 Km 163.5, I-34149 Trieste (Italy); Píš, Igor [Sincrotrone Trieste S.C.p.A., Area Science Park-Basovizza, Strada Statale 14 Km 163.5, I-34149 Trieste (Italy); Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park-Basovizza, Strada Statale 14 Km 163.5, I-34149 Trieste (Italy); Nappini, Silvia; Magnano, Elena; Bondino, Federica [Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park-Basovizza, Strada Statale 14 Km 163.5, I-34149 Trieste (Italy)

    2016-07-27

    The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This work reports a detailed investigation at the nanometer level of the Fe–graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, and scanning tunnelling microscopy. Quasi-freestanding graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

  5. A New Nonlinear Model of Body Resistance in Nanometer PD SOI MOSFETs

    Directory of Open Access Journals (Sweden)

    Arash Daghighi

    2011-01-01

    Full Text Available In this paper, a nonlinear model for the body resistance of a 45nm PD SOI MOSFET is developed. This model verified on the base of the small signal three-dimensional simulation results. In this paper by using the three-dimensional simulation of ISE-TCAD software, the indicating factors of body resistance in nanometer transistors and then are shown, using the surface potential model. A mathematical relation to calculat the body resistance incorporating device width and body potential was derived. Excellent agreement was obtained by comparing the model outputs and three-dimensional simulation results.

  6. The nature of the Fe-graphene interface at the nanometer level

    International Nuclear Information System (INIS)

    Cattelan, Mattia; Artiglia, Luca; Favaro, Marco; Agnoli, Stefano; Granozzi, Gaetano; Peng, Guowen; Roling, Luke T.; Mavrikakis, Manos; Cavaliere, Emanuele; Gavioli, Luca; Barinov, Alexey; Píš, Igor; Nappini, Silvia; Magnano, Elena; Bondino, Federica

    2016-01-01

    The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This work reports a detailed investigation at the nanometer level of the Fe–graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, and scanning tunnelling microscopy. Quasi-freestanding graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

  7. Nanometer-Scale Dissection of Chromosomes by Atomic Force Microscopy Combined with Heat-Denaturing Treatment

    Science.gov (United States)

    Tsukamoto, Kazumi; Kuwazaki, Seigo; Yamamoto, Kimiko; Shichiri, Motoharu; Yoshino, Tomoyuki; Ohtani, Toshio; Sugiyama, Shigeru

    2006-03-01

    We have developed a method for dissecting chromosome fragments with a size of a few hundred nanometers by atomic force microscopy (AFM). By using this method, we demonstrated reproducible dissections of silkworm chromosomes in the pachytene phase. The dissected fragments were successfully recovered on the cantilever tips, as confirmed by fluorescent microscopy using fluorescent stained chromosomes. To recover dissected chromosome fragments from a larger chromosome, such as the human metaphase chromosome of a somatic cell, heat denaturation was found to be effective. Further improvements in this method may lead to a novel tool for isolating valuable genes and/or investigating local genome structures in the near future.

  8. A direct and at nanometer scale study of electrical charge distribution on membranes of alive cells

    Directory of Open Access Journals (Sweden)

    Marlière Christian

    2016-01-01

    Full Text Available In this paper is presented an innovative method to map in-vivo and at nanometer scale the electrical charge distribution on membranes of alive cells. It relies on a new atomic force microscopy (AFM mode based on an electro-mechanical coupling effect. Furthermore, an additional electrical signal detected by both the deflection of the AFM cantilever and simultaneous direct current measurements was detected at low scanning rates. It was attributed to the detection of the current stemming from ionic channels. It opens a new way to directly investigate in situ biological electrical surface processes involved in bacterial adhesion, biofilm formation, microbial fuel cells, etc.

  9. Transmission electron microscopy studies on nanometer-sized ω phase produced in Gum Metal

    International Nuclear Information System (INIS)

    Yano, Takaaki; Murakami, Yasukazu; Shindo, Daisuke; Hayasaka, Yuichiro; Kuramoto, Shigeru

    2010-01-01

    The morphology, numerical density and average spacing of the ω phase formed in Gum Metal, a Ti-based alloy showing unique mechanical properties, were studied by transmission electron microscopy. Based on dark-field image observations and precise thickness measurements using a thin-foil specimen, the average spacing of the nanometer-sized ω phase was determined to be 6 nm. This spacing appeared to be sufficiently small for trapping dislocations. The results are discussed in conjunction with the dislocation-free deformation mechanism proposed for Gum Metal.

  10. Electron transport in nanometer GaAs structure under radiation exposure

    CERN Document Server

    Demarina, N V

    2002-01-01

    One investigates into effect of neutron and proton irradiation on electron transport in nanometer GaAs structures. Mathematical model takes account of radiation defects via introduction of additional mechanisms od scattering of carriers at point defects and disordered regions. To investigate experimentally into volt-ampere and volt-farad characteristics one used a structure based on a field-effect transistor with the Schottky gate and a built-in channel. Calculation results of electron mobility, drift rate of electrons, time of energy relaxation and electron pulse are compared with the experimental data

  11. Evolution of particle composition in CLOUD nucleation experiments

    CERN Document Server

    Keskinen, H; Joutsensaari, J; Tsagkogeorgas, G; Duplissy, J; Schobesberger, S; Gysel, M; Riccobono, F; Bianchi, F; Yli-Juuti, T; Lehtipalo, K; Rondo, L; Breitenlechner, M; Kupc, A; Almeida, J; Amorim, A; Dunne, E M; Downard, A J; Ehrhart, S; Franchin, A; Kajos, M K; Kirkby, J; Kurten, A; Nieminen, T; Makhmutov, V; Mathot, S; Miettinen, P; Onnela, A; Petaja, T; Praplan, A; Santos, F D; Schallhart, S; Sipila, M; Stozhkov, Y; Tome, A; Vaattovaara, P; Wimmer, D; Prevot, A; Dommen, J; Donahue, N M; Flagan, R C; Weingartner, E; Viisanen, Y; Riipinen, I; Hansel, A; Curtius, J; Kulmala, M; Worsnop, D R; Baltensperger, U; Wex, H; Stratmann, F; Laaksonen, A; Slowik, J G

    2013-01-01

    Sulphuric acid, ammonia, amines, and oxidised organics play a crucial role in nanoparticle formation in the atmosphere. In this study, we investigate the composition of nucleated nanoparticles formed from these compounds in the CLOUD (Cosmics Leaving Outdoor Droplets) chamber experiments at CERN (Centre europ ́ een pour la recherche nucl ́ eaire). The investigation was carried out via analysis of the particle hygroscopicity, ethanol affinity, oxidation state, and ion composition. Hygroscopicity was studied by a hygroscopic tandem differential mobility analyser and a cloud condensation nuclei counter, ethanol affinity by an organic differential mobility analyser and particle oxidation level by a high-resolution time-of-flight aerosol mass spectrometer. The ion composition was studied by an atmospheric pressure interface time-of-flight mass spectrometer. The volume fraction of the organics in the particles during theirgrowth from sizes of a few nanometers to tens of nanometers was derived from measured hygros...

  12. Fiscal 2000 achievement report on the research and development of nanometer controlled optical disk system; 2000 nendo nanometer seigyo hikari disk system no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    Development proceeded of nanometer controlled optical memory technologies as part of systematic research and development aiming at the reinforcement of industrial technology power in the field of data recording. Activities were conducted in the four fields of (1) high density signal processing technology, (2) high performance disk materials technology, (3) disk substrate fabrication technology, and (4) signal detection technology. Discussed in field (1) were multivalue ROM (read only memory) disk signal regeneration, SIL-LBR (solid immersion lens-laser beam recorder), dry etching process using RIE (reactive ion etching), SHG (second harmonic generation) blue laser, and a multivalue ROM disk evaluation system. Studied in field (2) were the evaluation of ROM disk performance dependent on recording materials, development of high density recording materials, and the evaluation of crystallization induction time using a static tester. Studied in the development of high density recording materials was the formation of microscopic recording marks in a phase shift/surface recording type disk comprising a 4-element (Ag-In-Sb-Te) recording layer and an Ag reflection layer. In fiscal 2000, an attempt was made at the 0.07 {mu}m level. (NEDO)

  13. Cleanability evaluation of ceramic glazes with nanometer far-infrared materials using contact angle measurement.

    Science.gov (United States)

    Wang, Lijuan; Liang, Jinsheng; Di, Xingfu; Tang, Qingguo

    2014-05-01

    The cleanability of easy-to-clean ceramic glazes doped with nanometer far-infrared materials was compared with that of some high-quality household ceramic glazes from the market. The cleanability was evaluated by the contact angle measurement using a sessile drop method with a Dataphysics OCA-30 contact angle analyzer. The results showed that the difference of contact angles of water on the glazes before soiling and after cleaning could be used as a parameter for evaluating the cleanability of the glazes. The relationship between cleanability and surface properties, such as surface free energy and surface topography, was investigated. The surface free energy of the samples and their components were calculated using van Oss acid-base approach. By measuring advancing and receding contact angles, the contact angle hysteresis of the ceramic glazes due to the surface topography was investigated. It was shown that the cleanability of ceramic glazes containing nanometer far-infrared materials (NFIM) is better than that of household ceramic glazes from market, due to a higher ratio of electron-acceptor parameter to electron-donor parameter, which led to the effect of water hydration as well as better hydrophilic property and increased smoothness. The contact angle measurement not only accurately evaluates the cleanability of the ceramic glazes, but also has a contribution to the study of cleanability theory. Moreover, this method is simple, convenient and less sample-consumption.

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

    Science.gov (United States)

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

    2018-01-01

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

  15. Generating Sub-nanometer Displacement Using Reduction Mechanism Consisting of Torsional Leaf Spring Hinges

    Directory of Open Access Journals (Sweden)

    Fukuda Makoto

    2014-02-01

    Full Text Available Recent demand on the measurement resolution of precise positioning comes up to tens of picometers. Some distinguished researches have been performed to measure the displacement in picometer order, however, few of them can verify the measurement performance as available tools in industry. This is not only because the picometer displacement is not yet required for industrial use, but also due to the lack of standard tools to verify such precise displacement. We proposed a displacement reduction mechanism for generating precise displacement using torsional leaf spring hinges (TLSHs that consist of four leaf springs arranged radially. It has been demonstrated that a prototype of the reduction mechanism was able to provide one-nanometer displacement with 1/1000 reduction rate by a piezoelectric actuator. In order to clarify the potential of the reduction mechanism, a displacement reduction table that can be mounted on AFM stage was newly developed using TLSHs. This paper describes the design of the reduction mechanism and the sub-nanometer displacement performance of the table obtained from its dynamic and static characteristics measured by displacement sensors and from the AFM images

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

    Science.gov (United States)

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

    2018-01-12

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

  17. Mapping Thermal Expansion Coefficients in Freestanding 2D Materials at the Nanometer Scale

    Science.gov (United States)

    Hu, Xuan; Yasaei, Poya; Jokisaari, Jacob; Öǧüt, Serdar; Salehi-Khojin, Amin; Klie, Robert F.

    2018-02-01

    Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, and photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation and thermal mismatch can be a problem in designing electronic devices based on two-dimensional materials. Quantifying the thermal expansion coefficient of 2D materials requires temperature measurements at nanometer scale. Here, we introduce a novel nanometer-scale thermometry approach to measure temperature and quantify the thermal expansion coefficients in 2D materials based on scanning transmission electron microscopy combined with electron energy-loss spectroscopy to determine the energy shift of the plasmon resonance peak of 2D materials as a function of sample temperature. By combining these measurements with first-principles modeling, the thermal expansion coefficients (TECs) of single-layer and freestanding graphene and bulk, as well as monolayer MoS2 , MoSe2 , WS2 , or WSe2 , are directly determined and mapped.

  18. Nanometal Skin of Plasmonic Heterostructures for Highly Efficient Near-Field Scattering Probes

    Science.gov (United States)

    Zito, Gianluigi; Rusciano, Giulia; Vecchione, Antonio; Pesce, Giuseppe; di Girolamo, Rocco; Malafronte, Anna; Sasso, Antonio

    2016-08-01

    In this work, atomic force microscopy probes are functionalized by virtue of self-assembling monolayers of block copolymer (BCP) micelles loaded either with clusters of silver nanoparticles or bimetallic heterostructures consisting of mixed species of silver and gold nanoparticles. The resulting self-organized patterns allow coating the tips with a sort of nanometal skin made of geometrically confined nanoislands. This approach favors the reproducible engineering and tuning of the plasmonic properties of the resulting structured tip by varying the nanometal loading of the micelles. The newly conceived tips are applied for experiments of tip-enhanced Raman scattering (TERS) spectroscopy and scattering-type scanning near-field optical microscopy (s-SNOM). TERS and s-SNOM probe characterizations on several standard Raman analytes and patterned nanostructures demonstrate excellent enhancement factor with the possibility of fast scanning and spatial resolution <12 nm. In fact, each metal nanoisland consists of a multiscale heterostructure that favors large scattering and near-field amplification. Then, we verify the tips to allow challenging nongap-TER spectroscopy on thick biosamples. Our approach introduces a synergistic chemical functionalization of the tips for versatile inclusion and delivery of plasmonic nanoparticles at the tip apex, which may promote the tuning of the plasmonic properties, a large enhancement, and the possibility of adding new degrees of freedom for tip functionalization.

  19. Transmission electron microscopical study of teenage crown dentin on the nanometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Panfilov, Peter, E-mail: peter.panfilov@urfu.ru [Ural Federal University, Ekaterinburg (Russian Federation); Kabanova, Anna [Ural Federal University, Ekaterinburg (Russian Federation); Guo, Jinming; Zhang, Zaoli [Erich Schmid Institute for Materials Science, Austrian Academy of Sciences, Leoben (Austria)

    2017-02-01

    Statement of significance: This is the first transmission electron microscopic study of teenage crown dentin on the nanometer scale. Samples for TEM were prepared by mechanical thinning and chemical polishing that allowed obtaining the electron transparent foils. It was firstly shown that human dentin possesses the layered morphology: the layers are oriented normally to the main axis of a tooth and have the thickness of ~ 50 nm. HA inorganic phase of teenage crown dentin is in the amorphous state. The cellular structure, which was formed from collagen fibers (diameter is ~ 5 nm), are observed near DEJ region in teenage dentin, whereas bioorganic phase of teenage crown dentin near the pulp camera does not contain the collagen fibers. Cracks in dentin thin foils have sharp tips, but big angles of opening (~ 30{sup °}) with plastic zone ahead crack tip. It means that young crown human dentin exhibits ductile or viscous-elastic fracture behavior on the nanometer scale. - Highlights: • Dentin has layered morphology. • Mineral component of dentin is in amorphous state. • Collagen fibers form cellular structure in dentin. • Cracks in dentin behave by elastic-plastic manner.

  20. Sub-nanometer-resolution imaging of peptide nanotubes in water using frequency modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sugihara, Tomoki; Hayashi, Itsuho; Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Kimura, Kenjiro, E-mail: kimura@gold.kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Tamura, Atsuo [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)

    2013-06-20

    Highlights: ► Peptide nanotubes were aligned on highly oriented pyrolytic graphite surface. ► We visualized sub-nanometer-scale structure on peptide nanotube surface in water. ► We observed hydration structure at a peptide nanotube/water interface. - Abstract: Peptide nanotubes are self-assembled fibrous materials composed of cyclic polypeptides. Recently, various aspects of peptide nanotubes have been studied, in particular the utility of different methods for making peptide nanotubes with diverse designed functions. In order to investigate the relationship between formation, function and stability, it is essential to analyze the precise structure of peptide nanotubes. Atomic-scale surface imaging in liquids was recently achieved using frequency modulation atomic force microscopy with improved force sensing. Here we provide a precise surface structural analysis of peptide nanotubes in water without crystallizing them obtained by imaging the nanotubes at the sub-nanometer scale in water. In addition, the local hydration structure around the peptide nanotubes was observed at the nanotube/water interface.

  1. Nanometer-size surface modification produced by single, low energy, highly charged ions

    International Nuclear Information System (INIS)

    Stockli, M.P.

    1994-01-01

    Atomically flat surfaces of insulators have been bombarded with low energy, highly charged ions to search for nanometer-size surface modifications. It is expected that the high electron deficiency of highly charged ions will capture and/or remove many of the insulator's localized electrons when impacting on an insulating surface. The resulting local electron deficiency is expected to locally disintegrate the insulator through a open-quotes Coulomb explosionclose quotes forming nanometer-size craters. Xe ions with charge states between 10+ and 45+ and kinetic energies between 0 and 10 keV/q were obtained from the KSU-CRYEBIS, a CRYogenic Electron Beam Ion Source and directed onto various insulating materials. Mica was favored as target material as atomically flat surfaces can be obtained reliably through cleaving. However, the authors observations with an atomic force microscope have shown that mica tends to defoliate locally rather than disintegrate, most likely due to the small binding forces between adjacent layers. So far the authors measurements indicate that each ion produces one blister if the charge state is sufficiently high. The blistering does not seem to depend very much on the kinetic energy of the ions

  2. Nanopore Measurements of Filamentous Viruses Reveal a Sub-nanometer-Scale Stagnant Fluid Layer.

    Science.gov (United States)

    McMullen, Angus J; Tang, Jay X; Stein, Derek

    2017-11-28

    We report measurements and analyses of nanopore translocations by fd and M13, two related strains of filamentous virus that are identical except for their charge densities. The standard continuum theory of electrokinetics greatly overestimates the translocation speed and the conductance associated with counterions for both viruses. Furthermore, fd and M13 behave differently from one another, even translocating in opposite directions under certain conditions. This cannot be explained by Manning-condensed counterions or a number of other proposed models. Instead, we argue that these anomalous findings are consequences of the breakdown of the validity of continuum hydrodynamics at the scale of a few molecular layers. Next to a polyelectrolyte, there exists an extra-viscous, sub-nanometer-thin boundary layer that has a giant influence on the transport characteristics. We show that a stagnant boundary layer captures the essential hydrodynamics and extends the validity of the electrokinetic theory beyond the continuum limit. A stagnant layer with a thickness of about half a nanometer consistently improves predictions of the ionic current change induced by virus translocations and of the translocation velocity for both fd and M13 over a wide range of nanopore dimensions and salt concentrations.

  3. Transmission electron microscopical study of teenage crown dentin on the nanometer scale

    International Nuclear Information System (INIS)

    Panfilov, Peter; Kabanova, Anna; Guo, Jinming; Zhang, Zaoli

    2017-01-01

    Statement of significance: This is the first transmission electron microscopic study of teenage crown dentin on the nanometer scale. Samples for TEM were prepared by mechanical thinning and chemical polishing that allowed obtaining the electron transparent foils. It was firstly shown that human dentin possesses the layered morphology: the layers are oriented normally to the main axis of a tooth and have the thickness of ~ 50 nm. HA inorganic phase of teenage crown dentin is in the amorphous state. The cellular structure, which was formed from collagen fibers (diameter is ~ 5 nm), are observed near DEJ region in teenage dentin, whereas bioorganic phase of teenage crown dentin near the pulp camera does not contain the collagen fibers. Cracks in dentin thin foils have sharp tips, but big angles of opening (~ 30 ° ) with plastic zone ahead crack tip. It means that young crown human dentin exhibits ductile or viscous-elastic fracture behavior on the nanometer scale. - Highlights: • Dentin has layered morphology. • Mineral component of dentin is in amorphous state. • Collagen fibers form cellular structure in dentin. • Cracks in dentin behave by elastic-plastic manner.

  4. Chemical-state-selective mapping at nanometer scale using synchrotron radiation and photoelectron emission microscopy

    International Nuclear Information System (INIS)

    Hirao, Norie; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori

    2010-01-01

    For surface analyses of semiconductor devices and various functional materials, it has become indispensable to analyze valence states at nanometer scale due to the rapid developments of nanotechnology. Since a method for microscopic mapping dependent on the chemical bond states has not been established so far, we have developed a photoelectron emission microscopy (PEEM) system combined with synchrotron soft X-ray excitation. The samples investigated were Si/SiO x micro-patterns prepared by O 2 + ion implantation in Si(001) wafer using a mask. PEEM images excited by various photon energies around the Si K-edge were observed. The lateral spatial resolution of the system was about 41 nm. The brightness of each spot in PEEM images changed depending on the photon energy, due to the X-ray absorption intensity of the respective chemical state. Since the surface of this sample was topographically flat, it has been demonstrated that the present method can be applied to observations of the microscopic pattern, depending not on the morphology, but only on the valence states of silicon. We have also in-situ measured the changes of the PEEM images upon annealing, and elucidated the mechanism of the lateral diffusion of oxygen and valence states of silicon at the nanometer scale. (author)

  5. Chemical-state-selective mapping at nanometer scale using synchrotron radiation and photoelectron emission microscopy

    International Nuclear Information System (INIS)

    Hirao, Norie; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori

    2008-01-01

    For surface analyses of semiconductor devices and various functional materials, it has become indispensable to analyze the valence states at the nanometer scale due to the rapid developments of nanotechnology. Since a method for microscopic mapping dependent on the chemical bond states has not been established so far, we have developed a photoelectron emission microscopy (PEEM) system combined with synchrotron soft X-ray excitation. The samples investigated were Si/SiO x micro-patterns prepared by O 2 + ion implantation in a Si(001) wafer using a mask. PEEM images excited by various photon energies around the Si K-edge were observed. The lateral spatial resolution of the system was about 41 nm. The brightness of each spot in PEEM images changed depending on the photon energy, due to the X-ray absorption intensity of the respective chemical state. Since the surface of this sample is topographically flat, it has been demonstrated that the present method can be applied to observations of the microscopic pattern, depending not on the morphology, but only on the valence states of silicon. We have also in-situ measured the changes of PEEM images upon annealing, and elucidated the mechanism of the lateral diffusion of oxygen and valence states of silicon at the nanometer scale. (author)

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

    Science.gov (United States)

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

    2003-07-01

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

  7. On arbitrarily graded rings

    Indian Academy of Sciences (India)

    58

    paper is devoted to the study of arbitrary rings graded through arbitrary sets. .... which recover certain multiplicative relations among the homogeneous components ... instance the case in which the grading set A is an Abelian group, where the ...

  8. Graded manifolds and supermanifolds

    International Nuclear Information System (INIS)

    Batchelor, M.

    1984-01-01

    In this paper, a review is presented on graded manifolds and supermanifolds. Many theorems, propositions, corrollaries, etc. are given with proofs or sketch proofs. Graded manifolds, supereuclidian space, Lie supergroups, etc. are dealt with

  9. Bridging the Gap between the Nanometer-Scale Bottom-Up and Micrometer-Scale Top-Down Approaches for Site-Defined InP/InAs Nanowires.

    Science.gov (United States)

    Zhang, Guoqiang; Rainville, Christophe; Salmon, Adrian; Takiguchi, Masato; Tateno, Kouta; Gotoh, Hideki

    2015-11-24

    This work presents a method that bridges the gap between the nanometer-scale bottom-up and micrometer-scale top-down approaches for site-defined nanostructures, which has long been a significant challenge for applications that require low-cost and high-throughput manufacturing processes. We realized the bridging by controlling the seed indium nanoparticle position through a self-assembly process. Site-defined InP nanowires were then grown from the indium-nanoparticle array in the vapor-liquid-solid mode through a "seed and grow" process. The nanometer-scale indium particles do not always occupy the same locations within the micrometer-scale open window of an InP exposed substrate due to the scale difference. We developed a technique for aligning the nanometer-scale indium particles on the same side of the micrometer-scale window by structuring the surface of a misoriented InP (111)B substrate. Finally, we demonstrated that the developed method can be used to grow a uniform InP/InAs axial-heterostructure nanowire array. The ability to form a heterostructure nanowire array with this method makes it possible to tune the emission wavelength over a wide range by employing the quantum confinement effect and thus expand the application of this technology to optoelectronic devices. Successfully pairing a controllable bottom-up growth technique with a top-down substrate preparation technique greatly improves the potential for the mass-production and widespread adoption of this technology.

  10. Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films

    International Nuclear Information System (INIS)

    Lu, Renguo; Zhang, Hedong; Komada, Suguru; Mitsuya, Yasunaga; Fukuzawa, Kenji; Itoh, Shintaro

    2014-01-01

    Highlights: • We present fine UV-patterning of nm-thick liquid films for surface functionalization. • The patterned films exhibit both a morphological pattern and a functional pattern of different surface properties. • The finest pattern linewidth was 0.5 μm. • Fine patterning is crucial for improving surface and tribological properties. - Abstract: For micro/nanoscale devices, surface functionalization is essential to achieve function and performance superior to those that originate from the inherent bulk material properties. As a method of surface functionalization, we dip-coated nanometer-thick liquid lubricant films onto solid surfaces and then patterned the lubricant films with ultraviolet (UV) irradiation through a photomask. Surface topography, adhesion, and friction measurements demonstrated that the patterned films feature a concave–convex thickness distribution with thicker lubricant in the irradiated regions and a functional distribution with lower adhesion and friction in the irradiated convex regions. The pattern linewidth ranged from 100 to as fine as 0.5 μm. The surface functionalization effect of UV-patterning was investigated by measuring the water contact angles, surface energies, friction forces, and depletion of the patterned, as-dipped, and full UV-irradiated lubricant films. The full UV-irradiated lubricant film was hydrophobic with a water contact angle of 102.1°, and had lower surface energy, friction, and depletion than the as-dipped film, which was hydrophilic with a water contact angle of 80.7°. This demonstrates that UV irradiation substantially improves the surface and tribological properties of the nanometer-thick liquid lubricant films. The UV-patterned lubricant films exhibited superior surface and tribological properties than the as-dipped film. The water contact angle increased and the surface energy, friction, and depletion decreased as the pattern linewidth decreased. In particular, the 0.5-μm patterned lubricant

  11. Report on achievements in fiscal 1999. Research and development of nanometer controlled optical disk system; 1999 nendo nanometer seigyo hikari disk system no kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Organizational strengthening is urged in industrial technological power in information recording area which is comparable with information communications being the main pillar of the innovation in the information technology in Japan. Extremely large expectations and heavy responsibilities are placed on the next generation optical memory technology, which is one of the strong points of Japan who plays a part in the above information recording area. The present project has been performing organizational research and development to achieve creation of new industries, with the following research themes as the main subjects: (1) nanometer controlled optical memory technology, (2) magnetic section responsive and three-dimensional optical memory, (3) ultra precision pit depicting technology, and (4) ultra precision pit measuring technology. The project is two years old this year, in which it was aimed to 'develop an optical memory technology with recording density of 100 Gb/in{sup 2} or more, transfer velocity of 100 Mbps or higher, and access time of 10 ms or less'. In order to achieve and establish the interim target set for fiscal 2000 among the above aims, intending 'trial fabrication of a disk having recording density of 40 to 50 Gb/in{sup 2}, the technical problem extraction and the specifications to realize a 100 Gb/in{sup 2} system', fiscal 1999 has performed researches on 'density and accuracy improvement on the prototype disk by improving the existing devices and introducing new devices'. This paper reports the developmental research theme No. 1. (NEDO)

  12. GRADE Equity Guidelines 3

    DEFF Research Database (Denmark)

    Welch, Vivian A; Akl, Elie A; Pottie, Kevin

    2017-01-01

    OBJECTIVE: The aim of this paper is to describe a conceptual framework for how to consider health equity in the GRADE (Grading Recommendations Assessment and Development Evidence) guideline development process. STUDY DESIGN AND SETTING: Consensus-based guidance developed by the GRADE working grou...

  13. Modern particle physics

    CERN Document Server

    AUTHOR|(CDS)2079874

    2013-01-01

    Unique in its coverage of all aspects of modern particle physics, this textbook provides a clear connection between the theory and recent experimental results, including the discovery of the Higgs boson at CERN. It provides a comprehensive and self-contained description of the Standard Model of particle physics suitable for upper-level undergraduate students and graduate students studying experimental particle physics. Physical theory is introduced in a straightforward manner with full mathematical derivations throughout. Fully-worked examples enable students to link the mathematical theory to results from modern particle physics experiments. End-of-chapter exercises, graded by difficulty, provide students with a deeper understanding of the subject. Online resources available at www.cambridge.org/MPP feature password-protected fully-worked solutions to problems for instructors, numerical solutions and hints to the problems for students and PowerPoint slides and JPEGs of figures from the book

  14. Physical and chemical characterization of fly ashes from Swiss waste incineration plants and determination of the ash fraction in the nanometer range.

    Science.gov (United States)

    Buha, Jelena; Mueller, Nicole; Nowack, Bernd; Ulrich, Andrea; Losert, Sabrina; Wang, Jing

    2014-05-06

    particle sizes, from nanometer range to micrometer range. Many aggregated particles were observed, demonstrating that ENO, bulk-derived nano-objects and combustion-generated nano-objects can form aggregates in the incineration process.

  15. Comparative studies of industrial grade carbon black powders

    Energy Technology Data Exchange (ETDEWEB)

    Chawla, Komal, E-mail: komalchawla.rs@gmail.com; Chauhan, Alok P. S., E-mail: chauhan.alok@gmail.com, E-mail: alok.chauhan@alumni.stonybrook.edu [Department of Physics and Material Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307, UP, India. (India)

    2016-05-06

    Comparative studies of two dissimilar industrial grade Carbon Black (CB) powders (N375 and N405) were conducted. The structure, surface area and particle size are the three important characteristics of CB powder that determine their processability and application as filler in preparing rubber compounds. The powders were characterized for their structure using dibutyl phthalate absorption (DBPA), particle size via laser particle size analyzer and surface area by nitrogen adsorption method. The structural characterization showed that N405 had lower DBPA in comparison to N375, confirming low structure of N405 grade CB powder. It was observed from the particle size analysis that N375 was coarser than N405 grade CB. The total surface area values were determined by the BET method based on the cross sectional area of the nitrogen molecule. N375, a coarse grade CB powder with high structure, depicted less surface area as compared to N405.

  16. Split Bull's eye shaped aluminum antenna for plasmon-enhanced nanometer scale germanium photodetector.

    Science.gov (United States)

    Ren, Fang-Fang; Ang, Kah-Wee; Ye, Jiandong; Yu, Mingbin; Lo, Guo-Qiang; Kwong, Dim-Lee

    2011-03-09

    Bull's eye antennas are capable of efficiently collecting and concentrating optical signals into an ultrasmall area, offering an excellent solution to break the bottleneck between speed and photoresponse in subwavelength photodetectors. Here, we exploit the idea of split bull's eye antenna for a nanometer germanium photodetector operating at a standard communication wavelength of 1310 nm. The nontraditional plasmonic metal aluminum has been implemented in the resonant antenna structure fabricated by standard complementary metal-oxide-semiconductor (CMOS) processing. A significant enhancement in photoresponse could be achieved over the conventional bull's eye scheme due to an increased optical near-field in the active region. Moreover, with this novel antenna design the effective grating area could be significantly reduced without sacrificing device performance. This work paves the way for the future development of low-cost, high-density, and high-speed CMOS-compatible germanium-based optoelectronic devices.

  17. Nanometer-Scale Chemistry of a Calcite Biomineralization Template: Implications for Skeletal Composition and Nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Branson, Oscar; Bonnin, Elisa A.; Perea, Daniel E.; Spero, Howard J.; Zhu, Zihua; Winters, Maria; Hönisch, Bärbel; Russell, Ann D.; Fehrenbacher, Jennifer S.; Gagnon, Alexander C.

    2016-10-28

    Biomineralizing organisms exhibit exquisite control over skeletal morphology and composition. The promise of understanding and harnessing this feat of natural engineering has motivated an intense search for the mechanisms that direct in vivo mineral self-assembly. We used atom probe tomography, a sub-nanometer 3D chemical mapping technique, to examine the chemistry of a buried organic-mineral interface in biomineral calcite from a marine foraminifer. The chemical patterns at this interface capture the processes of early biomineralization, when the shape, mineralogy, and orientation of skeletal growth are initially established. Sodium is enriched by a factor of nine on the organic side of the interface. Based on this pattern, we suggest that sodium plays an integral role in early biomineralization, potentially altering interfacial energy to promote crystal nucleation, and that interactions between organic surfaces and electrolytes other than calcium or carbonate could be a crucial aspect of CaCO3 biomineralization.

  18. Nanometer Linear Focusing of Hard X Rays by a Multilayer Laue Lens

    International Nuclear Information System (INIS)

    Kang, H.C.; Stephenson, G.B.; Maser, J.; Liu, C.; Conley, R.; Macrander, A.T.; Vogt, S.

    2006-01-01

    We report on a type of linear zone plate for nanometer-scale focusing of hard x rays, a multilayer Laue lens (MLL), produced by sectioning a multilayer and illuminating it in Laue diffraction geometry. Because of its large optical depth, a MLL spans the diffraction regimes applicable to a thin Fresnel zone plate and a crystal. Coupled wave theory calculations indicate that focusing to 5 nm or smaller with high efficiency should be possible. Partial MLL structures with outermost zone widths as small as 10 nm have been fabricated and tested with 19.5 keV synchrotron radiation. Focal sizes as small as 30 nm with efficiencies up to 44% are measured

  19. Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

    Institute of Scientific and Technical Information of China (English)

    史建明; 包永忠; 黄志明; 翁志学

    2004-01-01

    Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate (nano-CaCO3) surface modified with (-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

  20. Bimetallic Ag-Pt Sub-nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Negreiros, Fabio R. [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Halder, Avik [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Yin, Chunrong [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Singh, Akansha [Harish-Chandra Research Institute, HBNI, Chhatnag Road Jhunsi Allahabad 211019 India; Barcaro, Giovanni [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Sementa, Luca [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Tyo, Eric C. [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Pellin, Michael J. [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Bartling, Stephan [Institut für Physik, Universität Rostock, Rostock Germany; Meiwes-Broer, Karl-Heinz [Institut für Physik, Universität Rostock, Rostock Germany; Seifert, Sönke [X-ray Science Division, Argonne National Laboratory, Lemont IL USA; Sen, Prasenjit [Harish-Chandra Research Institute, HBNI, Chhatnag Road Jhunsi Allahabad 211019 India; Nigam, Sandeep [Chemistry Division, Bhabha Atomic Research Centre, Trombay Mumbai- 400 085 India; Majumder, Chiranjib [Chemistry Division, Bhabha Atomic Research Centre, Trombay Mumbai- 400 085 India; Fukui, Nobuyuki [East Tokyo Laboratory, Genesis Research Institute, Inc., Ichikawa Chiba 272-0001 Japan; Yasumatsu, Hisato [Cluster Research Laboratory, Toyota Technological Institute: in, East Tokyo Laboratory, Genesis Research Institute, Inc. Ichikawa, Chiba 272-0001 Japan; Vajda, Stefan [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Nanoscience and Technology Division, Argonne National Laboratory, Lemont IL USA; Institute for Molecular Engineering, University of Chicago, Chicago IL USA; Fortunelli, Alessandro [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Materials and Process Simulation Center, California Institute of Technology, Pasadena CA USA

    2017-12-29

    A combined experimental and theoretical investigation of Ag-Pt sub-nanometer clusters as heterogeneous catalysts in the CO -> CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size-selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first-principles simulations at realistic coverage. Insitu GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano-aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O-2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species.

  1. Mechanism of the superior mechanical strength of nanometer-sized metal single crystals revealed

    KAUST Repository

    Afify, N. D.

    2013-10-01

    Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them. © 2013 Published by Elsevier B.V.

  2. Consolidation of nanometer-sized aluminum single crystals: Microstructure and defects evolutions

    KAUST Repository

    Afify, N. D.

    2014-04-01

    Deriving bulk materials with ultra-high mechanical strength from nanometer-sized single metalic crystals depends on the consolidation procedure. We present an accurate molecular dynamics study to quantify microstructure responses to consolidation. Aluminum single crystals with an average size up to 10.7 nm were hydrostatically compressed at temperatures up to 900 K and pressures up to 5 GPa. The consolidated material developed an average grain size that grew exponentially with the consolidation temperature, with a growth rate dependent on the starting average grain size and the consolidation pressure. The evolution of the microstructure was accompanied by a significant reduction in the concentration of defects. The ratio of vacancies to dislocation cores decreased with the average grain size and then increased after reaching a critical average grain size. The deformation mechanisms of poly-crystalline metals can be better understood in the light of the current findings. © 2013 Elsevier B.V. All rights reserved.

  3. Mechanical design of ultraprecision weak-link stages for nanometer-scale x-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Shu, D [APS Engineering Support Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Maser, J, E-mail: shu@aps.anl.go [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2009-09-01

    A nanopositioning diagnostic setup has been built to support the Argonne Center for Nanoscale Materials (CNM) nanoprobe instrument commissioning process at the APS. Its laser Doppler interferometer system provides subnanometer positioning diagnostic resolution with large dynamic range. A set of original APS designed ultraprecision PZT-driven weak-link stages with high-stiffness motor-driven stages has been tested with this diagnostic setup. In this paper we present a preliminary test result of the ultraprecision weak-link stage system developed for the CNM hard x-ray nanoprobe instrument at APS sector 26. A test result for a novel laminar weak-link mechanism with sub-centimeter travel range and sub-nanometer positioning resolution is also introduced in this paper as a future work.

  4. Consolidation of nanometer-sized aluminum single crystals: Microstructure and defects evolutions

    KAUST Repository

    Afify, N. D.; Salem, H. G.; Yavari, A.; El Sayed, Tamer S.

    2014-01-01

    Deriving bulk materials with ultra-high mechanical strength from nanometer-sized single metalic crystals depends on the consolidation procedure. We present an accurate molecular dynamics study to quantify microstructure responses to consolidation. Aluminum single crystals with an average size up to 10.7 nm were hydrostatically compressed at temperatures up to 900 K and pressures up to 5 GPa. The consolidated material developed an average grain size that grew exponentially with the consolidation temperature, with a growth rate dependent on the starting average grain size and the consolidation pressure. The evolution of the microstructure was accompanied by a significant reduction in the concentration of defects. The ratio of vacancies to dislocation cores decreased with the average grain size and then increased after reaching a critical average grain size. The deformation mechanisms of poly-crystalline metals can be better understood in the light of the current findings. © 2013 Elsevier B.V. All rights reserved.

  5. Real-time detection of antibiotic activity by measuring nanometer-scale bacterial deformation

    Science.gov (United States)

    Iriya, Rafael; Syal, Karan; Jing, Wenwen; Mo, Manni; Yu, Hui; Haydel, Shelley E.; Wang, Shaopeng; Tao, Nongjian

    2017-12-01

    Diagnosing antibiotic-resistant bacteria currently requires sensitive detection of phenotypic changes associated with antibiotic action on bacteria. Here, we present an optical imaging-based approach to quantify bacterial membrane deformation as a phenotypic feature in real-time with a nanometer scale (˜9 nm) detection limit. Using this approach, we found two types of antibiotic-induced membrane deformations in different bacterial strains: polymyxin B induced relatively uniform spatial deformation of Escherichia coli O157:H7 cells leading to change in cellular volume and ampicillin-induced localized spatial deformation leading to the formation of bulges or protrusions on uropathogenic E. coli CFT073 cells. We anticipate that the approach will contribute to understanding of antibiotic phenotypic effects on bacteria with a potential for applications in rapid antibiotic susceptibility testing.

  6. The microstructural evolution of nanometer ruthenium films in Ru/C multilayers with thermal treatments

    International Nuclear Information System (INIS)

    Nguyen, T.D.; Gronsky, R.; Kortright, J.B.

    1991-04-01

    The evolution of nanometer Ru films sandwiched between various C layer thickness with thermal treatments was studied by plan-view and cross-sectional Transmission Electron Microscopy. Plan-view observation provides information on the Ru grain size, while cross- sectional studies allow examination of the multilayer morphology. After annealing at 800 degrees C for 30 minutes, the grain size in the 2 and 4 nm Ru layers show little difference from each other, while that in the 1 nm Ru layers depends strongly on the thickness of the C layers in the multilayers. It increases with decreasing C layer thickness. Agglomeration of the Ru layers is observed in 1nm Ru/1nm C multilayers after annealing at 600 degrees C for 30 minutes. The evolution of the microstructures and layered structure stability of the Ru/C system is compared to that of W/C and Ru/B 4 C systems. 10 refs., 2 figs

  7. Helium Ion Microscopy (HIM) for the imaging of biological samples at sub-nanometer resolution

    Science.gov (United States)

    Joens, Matthew S.; Huynh, Chuong; Kasuboski, James M.; Ferranti, David; Sigal, Yury J.; Zeitvogel, Fabian; Obst, Martin; Burkhardt, Claus J.; Curran, Kevin P.; Chalasani, Sreekanth H.; Stern, Lewis A.; Goetze, Bernhard; Fitzpatrick, James A. J.

    2013-12-01

    Scanning Electron Microscopy (SEM) has long been the standard in imaging the sub-micrometer surface ultrastructure of both hard and soft materials. In the case of biological samples, it has provided great insights into their physical architecture. However, three of the fundamental challenges in the SEM imaging of soft materials are that of limited imaging resolution at high magnification, charging caused by the insulating properties of most biological samples and the loss of subtle surface features by heavy metal coating. These challenges have recently been overcome with the development of the Helium Ion Microscope (HIM), which boasts advances in charge reduction, minimized sample damage, high surface contrast without the need for metal coating, increased depth of field, and 5 angstrom imaging resolution. We demonstrate the advantages of HIM for imaging biological surfaces as well as compare and contrast the effects of sample preparation techniques and their consequences on sub-nanometer ultrastructure.

  8. Non-equilibrium Green function method: theory and application in simulation of nanometer electronic devices

    International Nuclear Information System (INIS)

    Do, Van-Nam

    2014-01-01

    We review fundamental aspects of the non-equilibrium Green function method in the simulation of nanometer electronic devices. The method is implemented into our recently developed computer package OPEDEVS to investigate transport properties of electrons in nano-scale devices and low-dimensional materials. Concretely, we present the definition of the four real-time Green functions, the retarded, advanced, lesser and greater functions. Basic relations among these functions and their equations of motion are also presented in detail as the basis for the performance of analytical and numerical calculations. In particular, we review in detail two recursive algorithms, which are implemented in OPEDEVS to solve the Green functions defined in finite-size opened systems and in the surface layer of semi-infinite homogeneous ones. Operation of the package is then illustrated through the simulation of the transport characteristics of a typical semiconductor device structure, the resonant tunneling diodes. (review)

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

    Science.gov (United States)

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

    2013-03-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  11. Nanometer-Scale Pore Characteristics of Lacustrine Shale, Songliao Basin, NE China.

    Directory of Open Access Journals (Sweden)

    Min Wang

    Full Text Available In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale pores or fractures, so the pore types and PSDs (pore size distributions play a major role in the shale oil occurrence (free or absorbed state, amount of oil, and flow features. The pore types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale pores and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope observations, low pressure CO2 and N2 adsorption, and high-pressure mercury injection experiments. Analysis results indicate that: (1 Pore types in the lacustrine shale include inter-matrix pores, intergranular pores, organic matter pores, and dissolution pores, and these pores are dominated by mesopores and micropores; (2 There is no apparent correlation between pore volumes and clay content, however, a weak negative correlation is present between total pore volume and carbonate content; (3 Pores in lacustrine shale are well developed when the organic matter maturity (Ro is >1.0% and the pore volume is positively correlated with the TOC (total organic carbon content. The statistical results suggest that oil in lacustrine shale mainly occurs in pores with diameters larger than 40 nm. However, more research is needed to determine whether this minimum pore diameter for oil occurrence in lacustrine shale is widely applicable.

  12. Helium Ion Microscope: A New Tool for Sub-nanometer Imaging of Soft Materials

    Science.gov (United States)

    Shutthanandan, V.; Arey, B.; Smallwood, C. R.; Evans, J. E.

    2017-12-01

    High-resolution inspection of surface details is needed in many biological and environmental researches to understand the Soil organic material (SOM)-mineral interactions along with identifying microbial communities and their interactions. SOM shares many imaging characteristics with biological samples and getting true surface details from these materials are challenging since they consist of low atomic number materials. FE-SEM imaging is the main imagining technique used to image these materials in the past. These SEM images often show loss of resolution and increase noise due to beam damage and charging issues. Newly developed Helium Ion Microscope (HIM), on the other hand can overcome these difficulties and give very fine details. HIM is very similar to scanning electron microscopy (SEM) but instead of using electrons as a probe beam, HIM uses helium ions with energy ranges from 5 to 40 keV. HIM offers a series of advantages compared to SEM such as nanometer and sub-nanometer image resolutions (about 0.35 nm), detailed surface topography, high surface sensitivity, low Z material imaging (especially for polymers and biological samples), high image contrast, and large depth of field. In addition, HIM also has the ability to image insulating materials without any conductive coatings so that surface details are not modified. In this presentation, several scientific applications across biology and geochemistry will be presented to highlight the effectiveness of this powerful microscope. Acknowledgements: Research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at PNNL. Work was supported by DOE-BER Mesoscale to Molecules Bioimaging Project FWP# 66382.

  13. Electrospray ionizer for mass spectrometry of aerosol particles

    Science.gov (United States)

    He, Siqin; Hogan, Chris; Li, Lin; Liu, Benjamin Y. H.; Naqwi, Amir; Romay, Francisco

    2017-09-19

    A device and method are disclosed to apply ESI-based mass spectroscopy to submicrometer and nanometer scale aerosol particles. Unipolar ionization is utilized to charge the particles in order to collect them electrostatically on the tip of a tungsten rod. Subsequently, the species composing the collected particles are dissolved by making a liquid flow over the tungsten rod. This liquid with dissolved aerosol contents is formed into highly charged droplets, which release unfragmented ions for mass spectroscopy, such as time-of-flight mass spectroscopy. The device is configured to operate in a switching mode, wherein aerosol deposition occurs while solvent delivery is turned off and vice versa.

  14. Graded gauge theory

    International Nuclear Information System (INIS)

    Kerner, R.

    1983-01-01

    The mathematical background for a graded extension of gauge theories is investigated. After discussing the general properties of graded Lie algebras and what may serve as a model for a graded Lie group, the graded fiber bundle is constructed. Its basis manifold is supposed to be the so-called superspace, i.e. the product of the Minkowskian space-time with the Grassmann algebra spanned by the anticommuting Lorentz spinors; the vertical subspaces tangent to the fibers are isomorphic with the graded extension of the SU(N) Lie algebra. The connection and curvature are defined then on this bundle; the two different gradings are either independent of each other, or may be unified in one common grading, which is equivalent to the choice of the spin-statistics dependence. The Yang-Mills lagrangian is investigated in the simplified case. The conformal symmetry breaking is discussed, as well as some other physical consequences of the model. (orig.)

  15. Optical tweezers in concentrated colloidal dispersions : Manipulating and imaging individual particles

    NARCIS (Netherlands)

    Vossen, Dirk Leo Joep

    2004-01-01

    Using a laser beam that is focused down to a diffraction-limited spot, particles with a size ranging from several nanometers up to tens of micrometers can be trapped and manipulated. This technique, known as "optical tweezers" or "optical trapping", has been used in a wide variety of

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

    Science.gov (United States)

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

    2014-03-01

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

  17. Surface enhanced Raman scattering of gold nanoparticles supported on copper foil with graphene as a nanometer gap

    International Nuclear Information System (INIS)

    Xiang, Quan; Zhu, Xupeng; Chen, Yiqin; Duan, Huigao

    2016-01-01

    Gaps with single-nanometer dimensions (<10 nm) between metallic nanostructures enable giant local field enhancements for surface enhanced Raman scattering (SERS). Monolayer graphene is an ideal candidate to obtain a sub-nanometer gap between plasmonic nanostructures. In this work, we demonstrate a simple method to achieve a sub-nanometer gap by dewetting a gold film supported on monolayer graphene grown on copper foil. The Cu foil can serve as a low-loss plasmonically active metallic film that supports the imaginary charge oscillations, while the graphene can not only create a stable sub-nanometer gap for massive plasmonic field enhancements but also serve as a chemical enhancer. We obtained higher SERS enhancements in this graphene-gapped configuration compared to those in Au nanoparticles on Cu film or on graphene–SiO 2 –Si. Also, the Raman signals measured maintained their fine features and intensities over a long time period, indicating the stability of this Au–graphene–Cu hybrid configuration as an SERS substrate. (paper)

  18. Comparison between XAS, AWAXS and DAFS applied to nanometer scale supported metallic clusters. Pt.1; monometallic clusters

    International Nuclear Information System (INIS)

    Bazin, D.C.; Sayers, D.A.

    1993-01-01

    The structural information found using three techniques related to synchrotron radiation are compared. XAS (X-ray Absorption Spectroscopy), AWAXS (Anomalous Wide Angle X-ray Scattering) and DAFS (Diffraction Anomalous Fine Structure) are applied to nanometer scale metallic clusters. (author)

  19. Comparison between XAS, AWAXS and DAFS applied to nanometer scale supported metallic clusters. Pt.2; bimetallic clusters

    International Nuclear Information System (INIS)

    Bazin, D.; Sayers, D.

    1993-01-01

    The structural information obtained using three techniques related to synchrotron radiation are compared. XAS (X-ray Absorption Spectroscopy), AWAXS (Anomalous Wide Angle X-ray Scattering) and DAFS (Diffraction Anomalous Fine Structure) are applied to the study of nanometer scale bimetallic clusters. (author)

  20. Real-Time Imaging of Plant Cell Wall Structure at Nanometer Scale, with Respect to Cellulase Accessibility and Degradation Kinetics (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Ding, S. Y.

    2012-05-01

    Presentation on real-time imaging of plant cell wall structure at nanometer scale. Objectives are to develop tools to measure biomass at the nanometer scale; elucidate the molecular bases of biomass deconstruction; and identify factors that affect the conversion efficiency of biomass-to-biofuels.

  1. Graded tensor calculus

    International Nuclear Information System (INIS)

    Scheunert, M.

    1982-10-01

    We develop a graded tensor calculus corresponding to arbitrary Abelian groups of degrees and arbitrary commutation factors. The standard basic constructions and definitions like tensor products, spaces of multilinear mappings, contractions, symmetrization, symmetric algebra, as well as the transpose, adjoint, and trace of a linear mapping, are generalized to the graded case and a multitude of canonical isomorphisms is presented. Moreover, the graded versions of the classical Lie algebras are introduced and some of their basic properties are described. (orig.)

  2. Rare particles

    International Nuclear Information System (INIS)

    Kutschera, W.

    1984-01-01

    The use of Accelerator Mass Spectrometry (AMS) to search for hypothetical particles and known particles of rare processes is discussed. The hypothetical particles considered include fractionally charged particles, anomalously heavy isotopes, and superheavy elements. The known particles produced in rare processes discussed include doubly-charged negative ions, counting neutrino-produced atoms in detectors for solar neutrino detection, and the spontaneous emission of 14 C from 223 Ra. 35 references

  3. Fabrication of Micrometer- and Nanometer-Scale Polymer Structures by Visible Light Induced Dielectrophoresis (DEP Force

    Directory of Open Access Journals (Sweden)

    Wen J. Li

    2011-12-01

    Full Text Available We report in this paper a novel, inexpensive and flexible method for fabricating micrometer- and nanometer-scale three-dimensional (3D polymer structures using visible light sources instead of ultra-violet (UV light sources or lasers. This method also does not require the conventional micro-photolithographic technique (i.e., photolithographic masks for patterning and fabricating polymer structures such as hydrogels. The major materials and methods required for this novel fabrication technology are: (1 any cross-linked network of photoactive polymers (examples of fabricated poly(ethylene glycol (PEG-diacrylate hydrogel structures are shown in this paper; (2 an Optically-induced Dielectrophoresis (ODEP System which includes an “ODEP chip” (i.e., any chip that changes its surface conductivity when exposed to visible light, an optical microscope, a projector, and a computer; and (3 an animator software hosted on a computer that can generate virtual or dynamic patterns which can be projected onto the “ODEP chip” through the use of a projector and a condenser lens. Essentially, by placing a photosensitive polymer solution inside the microfluidic platform formed by the “ODEP chip” bonded to another substrate, and applying an alternating current (a.c. electrical potential across the polymer solution (typically ~20 Vp-p at 10 kHz, solid polymer micro/nano structures can then be formed on the “ODEP chip” surface when visible-light is projected onto the chip. The 2D lateral geometry (x and y dimensions and the thickness (height of the micro/nano structures are dictated by the image geometry of the visible light projected onto the “ODEP chip” and also the time duration of projection. Typically, after an image projection with intensity ranging from ~0.2 to 0.4 mW/cm2 for 10 s, ~200 nm high structures can be formed. In our current system, the thickness of these polymer structures can be controlled to form from ~200 nanometers to ~3

  4. Probing Local Ionic Dynamics in Functional Oxides: From Nanometer to Atomic Scale

    Science.gov (United States)

    Kalinin, Sergei

    2014-03-01

    Vacancy-mediated electrochemical reactions in oxides underpin multiple applications ranging from electroresistive memories, to chemical sensors to energy conversion systems such as fuel cells. Understanding the functionality in these systems requires probing reversible (oxygen reduction/evolution reaction) and irreversible (cathode degradation and activation, formation of conductive filaments) electrochemical processes. In this talk, I summarize recent advances in probing and controlling these transformations locally on nanometer level using scanning probe microscopy. The localized tip concentrates the electric field in the nanometer scale volume of material, inducing local transition. Measured simultaneously electromechanical response (piezoresponse) or current (conductive AFM) provides the information on the bias-induced changes in material. Here, I illustrate how these methods can be extended to study local electrochemical transformations, including vacancy dynamics in oxides such as titanates, LaxSr1-xCoO3, BiFeO3, and YxZr1-xO2. The formation of electromechanical hysteresis loops and their bias-, temperature- and environment dependences provide insight into local electrochemical mechanisms. In materials such as lanthanum-strontium cobaltite, mapping both reversible vacancy motion and vacancy ordering and static deformation is possible, and can be corroborated by post mortem STEM/EELS studies. In ceria, a broad gamut of electrochemical behaviors is observed as a function of temperature and humidity. The possible strategies for elucidation ionic motion at the electroactive interfaces in oxides using high-resolution electron microscopy and combined ex-situ and in-situ STEM-SPM studies are discussed. In the second part of the talk, probing electrochemical phenomena on in-situ grown surfaces with atomic resolution is illustrated. I present an approach based on the multivariate statistical analysis of the coordination spheres of individual atoms to reveal

  5. Atom probe characterization of yttria particles in ODS Eurofer steel

    International Nuclear Information System (INIS)

    Aleev, A.A.; Zaluzhny, A.G.; Nikitin, A.A.; Rogozhkin, S.V.; Iskandarov, N.A.; Vladimirov, P.; Moeslang, A.; Lindau, R.; Klimenkov, M.

    2009-01-01

    Oxide dispersion strengthened steels exhibit higher temperature and radiation resistance than conventionally produced ferritic/martensitic steels. Such behaviour, as believed, is mainly caused by presence of highly dispersed and extremely stable oxide particles with sizes of few nanometers. It was shown that the most promising oxide additive was yttria (Y 2 O 3 ) and as mechanical parameters were strongly depended on size and number density of formed peculiarities it is required to reduce their dimensions to few nanometers and drastically increase their number. At present, considerable effort is focused on investigation of behaviour and properties of such particles. Recent studies of Eurofer ODS steel (9%-CrWVTa) by SANS and PoAS revealed the presence of high number density structural peculiarities with size approximately one nanometer. At the same time, previous studies by TEM identified only high number of small (5-10 nm) Y 2 O 3 particles. So, the purpose of this work was to look into this material by means of tomographic atom probe and find out the chemistry and origin of peculiarities with sizes less than 5 nm. These investigations revealed fine (∼ 2 nm) particles that were enriched not only in yttrium and oxygen but also in vanadium and nitrogen. Concentration of vanadium in them is approximately at the same level as yttrium. Moreover, some particles were found to be enriched in only three or even two elements mentioned above. However, total concentration of chemical elements in these particles is considerably less than that of iron. Estimated number density for detected particles is (1 / 5) x 10 23 m -3 . (author)

  6. Size effect in X-ray and electron diffraction patterns from hydroxyapatite particles

    International Nuclear Information System (INIS)

    Suvorova, E.I.; Buffat, P.-A.

    2001-01-01

    High-resolution transmission electron microscopy (HRTEM), electron microdiffraction, and X-ray diffraction were used to study hydroxyapatite specimens with particle sizes from a few nanometers to several hundreds of nanometers. Diffuse scattering (without clear reflections in transmission diffraction patterns) or strongly broadened peaks in X-ray diffraction patterns are characteristic for agglomerated hydroxyapatite nanocrystals. However, HRTEM and microdiffraction showed that this cannot be considered as an indication of the amorphous state of the matter but rather as the demonstration of size effect and the morphological and structural features of hydroxyapatite nanocrystals

  7. Classroom: Efficient Grading

    Science.gov (United States)

    Shaw, David D.; Pease, Leonard F., III.

    2014-01-01

    Grading can be accelerated to make time for more effective instruction. This article presents specific time management strategies selected to decrease administrative time required of faculty and teaching assistants, including a multiple answer multiple choice interface for exams, a three-tier grading system for open ended problem solving, and a…

  8. Grain Grading and Handling.

    Science.gov (United States)

    Rendleman, Matt; Legacy, James

    This publication provides an introduction to grain grading and handling for adult students in vocational and technical education programs. Organized in five chapters, the booklet provides a brief overview of the jobs performed at a grain elevator and of the techniques used to grade grain. The first chapter introduces the grain industry and…

  9. Virtual rough samples to test 3D nanometer-scale scanning electron microscopy stereo photogrammetry.

    Science.gov (United States)

    Villarrubia, J S; Tondare, V N; Vladár, A E

    2016-01-01

    The combination of scanning electron microscopy for high spatial resolution, images from multiple angles to provide 3D information, and commercially available stereo photogrammetry software for 3D reconstruction offers promise for nanometer-scale dimensional metrology in 3D. A method is described to test 3D photogrammetry software by the use of virtual samples-mathematical samples from which simulated images are made for use as inputs to the software under test. The virtual sample is constructed by wrapping a rough skin with any desired power spectral density around a smooth near-trapezoidal line with rounded top corners. Reconstruction is performed with images simulated from different angular viewpoints. The software's reconstructed 3D model is then compared to the known geometry of the virtual sample. Three commercial photogrammetry software packages were tested. Two of them produced results for line height and width that were within close to 1 nm of the correct values. All of the packages exhibited some difficulty in reconstructing details of the surface roughness.

  10. Probing dynamics and pinning of single vortices in superconductors at nanometer scales

    Science.gov (United States)

    Embon, L.; Anahory, Y.; Suhov, A.; Halbertal, D.; Cuppens, J.; Yakovenko, A.; Uri, A.; Myasoedov, Y.; Rappaport, M. L.; Huber, M. E.; Gurevich, A.; Zeldov, E.

    2015-01-01

    The dynamics of quantized magnetic vortices and their pinning by materials defects determine electromagnetic properties of superconductors, particularly their ability to carry non-dissipative currents. Despite recent advances in the understanding of the complex physics of vortex matter, the behavior of vortices driven by current through a multi-scale potential of the actual materials defects is still not well understood, mostly due to the scarcity of appropriate experimental tools capable of tracing vortex trajectories on nanometer scales. Using a novel scanning superconducting quantum interference microscope we report here an investigation of controlled dynamics of vortices in lead films with sub-Angstrom spatial resolution and unprecedented sensitivity. We measured, for the first time, the fundamental dependence of the elementary pinning force of multiple defects on the vortex displacement, revealing a far more complex behavior than has previously been recognized, including striking spring softening and broken-spring depinning, as well as spontaneous hysteretic switching between cellular vortex trajectories. Our results indicate the importance of thermal fluctuations even at 4.2 K and of the vital role of ripples in the pinning potential, giving new insights into the mechanisms of magnetic relaxation and electromagnetic response of superconductors.

  11. Engineering polyelectrolyte multilayer structure at the nanometer length scale by tuning polymer solution conformation.

    Science.gov (United States)

    Boddohi, Soheil; Killingsworth, Christopher; Kipper, Matt

    2008-03-01

    Chitosan (a weak polycation) and heparin (a strong polyanion) are used to make polyelectrolyte multilayers (PEM). PEM thickness and composition are determined as a function of solution pH (4.6 to 5.8) and ionic strength (0.1 to 0.5 M). Over this range, increasing pH increases the PEM thickness; however, the sensitivity to changes in pH is a strong function of ionic strength. The PEM thickness data are correlated to the polymer conformation in solution. Polyelectrolyte conformation in solution is characterized by gel permeation chromatography (GPC). The highest sensitivity of PEM structure to pH is obtained at intermediate ionic strength. Different interactions govern the conformation and adsorption phenomena at low and high ionic strength, leading to reduced sensitivity to solution pH at extreme ionic strengths. The correspondence between PEM thickness and polymer solution conformation offers opportunities to tune polymer thin film structure at the nanometer length scale by controlling simple, reproducible processing conditions.

  12. Drift-insensitive distributed calibration of probe microscope scanner in nanometer range: Virtual mode

    Science.gov (United States)

    Lapshin, Rostislav V.

    2016-08-01

    A method of distributed calibration of a probe microscope scanner is suggested. The main idea consists in a search for a net of local calibration coefficients (LCCs) in the process of automatic measurement of a standard surface, whereby each point of the movement space of the scanner can be characterized by a unique set of scale factors. Feature-oriented scanning (FOS) methodology is used as a basis for implementation of the distributed calibration permitting to exclude in situ the negative influence of thermal drift, creep and hysteresis on the obtained results. Possessing the calibration database enables correcting in one procedure all the spatial systematic distortions caused by nonlinearity, nonorthogonality and spurious crosstalk couplings of the microscope scanner piezomanipulators. To provide high precision of spatial measurements in nanometer range, the calibration is carried out using natural standards - constants of crystal lattice. One of the useful modes of the developed calibration method is a virtual mode. In the virtual mode, instead of measurement of a real surface of the standard, the calibration program makes a surface image ;measurement; of the standard, which was obtained earlier using conventional raster scanning. The application of the virtual mode permits simulation of the calibration process and detail analysis of raster distortions occurring in both conventional and counter surface scanning. Moreover, the mode allows to estimate the thermal drift and the creep velocities acting while surface scanning. Virtual calibration makes possible automatic characterization of a surface by the method of scanning probe microscopy (SPM).

  13. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    Science.gov (United States)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-12-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

  14. Multilayer Laue Lens: A Path Toward One Nanometer X-Ray Focusing

    International Nuclear Information System (INIS)

    Yan, H.; Stephenson, G.B.; Maser, J.; Yan, H.; Conley, R.; Kang, H.C.; Stephenson, G.B.; Kang, H.C.; Maser, J.; Conley, R.; Liu, Ch.; Macrander, A.T.

    2010-01-01

    The multilayer Laue lens (MLL) is a novel diffractive optic for hard X-ray nano focusing, which is fabricated by thin film deposition techniques and takes advantage of the dynamical diffraction effect to achieve a high numerical aperture and efficiency. It overcomes two difficulties encountered in diffractive optics fabrication for focusing hard X-rays: (1) small outmost zone width and (2) high aspect ratio. Here, we will give a review on types, modeling approaches, properties, fabrication, and characterization methods of MLL optics. We show that a full-wave dynamical diffraction theory has been developed to describe the dynamical diffraction property of the MLL and has been employed to design the optimal shapes for nano focusing. We also show a 16 nm line focus obtained by a partial MLL and several characterization methods. Experimental results show a good agreement with the theoretical calculations. With the continuing development of MLL optics, we believe that an MLL-based hard x-ray microscope with true nanometer resolution is on the horizon

  15. Fabrication of 200 nanometer period centimeter area hard x-ray absorption gratings by multilayer deposition

    Science.gov (United States)

    Lynch, S K; Liu, C; Morgan, N Y; Xiao, X; Gomella, A A; Mazilu, D; Bennett, E E; Assoufid, L; de Carlo, F; Wen, H

    2012-01-01

    We describe the design and fabrication trials of x-ray absorption gratings of 200 nm period and up to 100:1 depth-to-period ratios for full-field hard x-ray imaging applications. Hard x-ray phase-contrast imaging relies on gratings of ultra-small periods and sufficient depth to achieve high sensitivity. Current grating designs utilize lithographic processes to produce periodic vertical structures, where grating periods below 2.0 μm are difficult due to the extreme aspect ratios of the structures. In our design, multiple bilayers of x-ray transparent and opaque materials are deposited on a staircase substrate, and mostly on the floor surfaces of the steps only. When illuminated by an x-ray beam horizontally, the multilayer stack on each step functions as a micro-grating whose grating period is the thickness of a bilayer. The array of micro-gratings over the length of the staircase works as a single grating over a large area when continuity conditions are met. Since the layers can be nanometers thick and many microns wide, this design allows sub-micron grating periods and sufficient grating depth to modulate hard x-rays. We present the details of the fabrication process and diffraction profiles and contact radiography images showing successful intensity modulation of a 25 keV x-ray beam. PMID:23066175

  16. Probing Rubber Cross-Linking Generation of Industrial Polymer Networks at Nanometer Scale.

    Science.gov (United States)

    Gabrielle, Brice; Gomez, Emmanuel; Korb, Jean-Pierre

    2016-06-23

    We present improved analyses of rheometric torque measurements as well as (1)H double-quantum (DQ) nuclear magnetic resonance (NMR) buildup data on polymer networks of industrial compounds. This latter DQ NMR analysis allows finding the distribution of an orientation order parameter (Dres) resulting from the noncomplete averaging of proton dipole-dipole couplings within the cross-linked polymer chains. We investigate the influence of the formulation (filler and vulcanization systems) as well as the process (curing temperature) ending to the final polymer network. We show that DQ NMR follows the generation of the polymer network during the vulcanization process from a heterogeneous network to a very homogeneous one. The time variations of microscopic Dres and macroscopic rheometric torques present power-law behaviors above a threshold time scale with characteristic exponents of the percolation theory. We observe also a very good linear correlation between the kinetics of Dres and rheometric data routinely performed in industry. All these observations confirm the description of the polymer network generation as a critical phenomenon. On the basis of all these results, we believe that DQ NMR could become a valuable tool for investigating in situ the cross-linking of industrial polymer networks at the nanometer scale.

  17. Size-dependent elastic/inelastic behavior of enamel over millimeter and nanometer length scales.

    Science.gov (United States)

    Ang, Siang Fung; Bortel, Emely L; Swain, Michael V; Klocke, Arndt; Schneider, Gerold A

    2010-03-01

    The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel's elastic/inelastic transition over four hierarchical length scales, namely: 'bulk enamel' (mm), 'multiple-rod' (10's microm), 'intra-rod' (100's nm with multiple crystallites) and finally 'single-crystallite' (10's nm with an area of approximately one hydroxyapatite crystallite). The enamel's elastic/inelastic transitions were observed at 0.4-17 GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius approximately 20 nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size approximately 2 mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed. (c) 2009 Elsevier Ltd. All rights reserved.

  18. Control of the interaction strength of photonic molecules by nanometer precise 3D fabrication.

    Science.gov (United States)

    Rawlings, Colin D; Zientek, Michal; Spieser, Martin; Urbonas, Darius; Stöferle, Thilo; Mahrt, Rainer F; Lisunova, Yuliya; Brugger, Juergen; Duerig, Urs; Knoll, Armin W

    2017-11-28

    Applications for high resolution 3D profiles, so-called grayscale lithography, exist in diverse fields such as optics, nanofluidics and tribology. All of them require the fabrication of patterns with reliable absolute patterning depth independent of the substrate location and target materials. Here we present a complete patterning and pattern-transfer solution based on thermal scanning probe lithography (t-SPL) and dry etching. We demonstrate the fabrication of 3D profiles in silicon and silicon oxide with nanometer scale accuracy of absolute depth levels. An accuracy of less than 1nm standard deviation in t-SPL is achieved by providing an accurate physical model of the writing process to a model-based implementation of a closed-loop lithography process. For transfering the pattern to a target substrate we optimized the etch process and demonstrate linear amplification of grayscale patterns into silicon and silicon oxide with amplification ratios of ∼6 and ∼1, respectively. The performance of the entire process is demonstrated by manufacturing photonic molecules of desired interaction strength. Excellent agreement of fabricated and simulated structures has been achieved.

  19. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

  20. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

  1. Determination of mercury and selenium in herbal medicines and hair by using a nanometer TiO2-coated quartz tube atomizer and hydride generation atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Li, Shun-Xing; Zheng, Feng-Ying; Cai, Shu-Jie; Cai, Tian-Shou

    2011-01-01

    The nanometer TiO 2 particle was coated onto the inner wall of a T-shaped quartz tube atomizer (QTA) and then was used as a new atomizer (NT-QTA) for the determination of Hg and Se by hydride generation atomic absorption spectrometry (HGAAS). After coating 67.4 mg TiO 2 on a quartz tube, the analytical performance of NT-QTA-HGAAS was compared to conventional QTA-HGAAS and it was improved as follows: (a) the linear range of the calibration curves was expanded from 10.0-80.0 ng mL -1 to 5.0-150.0 ng mL -1 for Hg, and from 10.0-70.0 ng mL -1 to 5.0-100.0 ng mL -1 for Se; (b) the characteristic concentration of was decreased from 2.8 ng mL -1 /1% to 1.1 ng mL -1 /1% for Hg and from 1.2 ng mL -1 /1% to 0.8 ng mL -1 /1% for Se; and (c) the interference from the coexistence of As on the determination of Hg and Se could be eliminated. The achieved technique was applied for the determination of Hg and Se in herbal medicines and hair.

  2. Resolving the three-dimensional microstructure of polymer electrolyte fuel cell electrodes using nanometer-scale X-ray computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Epting, William K.; Gelb, Jeff; Litster, Shawn

    2012-02-08

    The electrodes of a polymer electrolyte fuel cell (PEFC) are composite porous layers consisting of carbon and platinum nanoparticles and a polymer electrolyte binder. The proper composition and arrangement of these materials for fast reactant transport and high electrochemical activity is crucial to achieving high performance, long lifetimes, and low costs. Here, the microstructure of a PEFC electrode using nanometer-scale X-ray computed tomography (nano-CT) with a resolution of 50 nm is investigated. The nano-CT instrument obtains this resolution for the low-atomic-number catalyst support and binder using a combination of a Fresnel zone plate objective and Zernike phase contrast imaging. High-resolution, non-destructive imaging of the three-dimensional (3D) microstructures provides important new information on the size and form of the catalyst particle agglomerates and pore spaces. Transmission electron microscopy (TEM) and mercury intrusion porosimetry (MIP) is applied to evaluate the limits of the resolution and to verify the 3D reconstructions. The computational reconstructions and size distributions obtained with nano-CT can be used for evaluating electrode preparation, performing pore-scale simulations, and extracting effective morphological parameters for large-scale computational models. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Particle detection

    International Nuclear Information System (INIS)

    Charpak, G.

    2000-01-01

    In this article G.Charpak presents the principles on which particle detection is based. Particle accelerators are becoming more and more powerful and require new detectors able to track the right particle in a huge flux of particles. The gigantic size of detectors in high energy physics is often due to the necessity of getting a long enough trajectory in a magnetic field in order to deduce from the curvature an accurate account of impulses in the reaction. (A.C.)

  4. Spinel Li{sub 2}CoTi{sub 3}O{sub 8} nanometer obtained for application as pigment; Espinela Li{sub 2}CoTi{sub 3}O{sub 8} nanometrica obtenida para aplicacion como pigmento

    Energy Technology Data Exchange (ETDEWEB)

    Costa de Camara, M. S.; Alves Pimentel, L.; Longo, E.; Nobrega Azevedo, L. da; Araujo Melo, D. M. de

    2016-05-01

    Pigments are used in ceramics, cosmetics, inks, and other applications widely materials. To this must be single and easily reproducible. Moreover, the pigments obtained in the nanoscale are more stable, reproducible and highlight color in small amounts compared with those obtained in micrometer scale. The mixed oxides with spinel structures AB{sub 2}O{sub 4} have important applications, including: pigments, refractories, catalytic and electronic ceramics. In this context, the aim of this work was the preparation of powder Li{sub 2}CoTi{sub 3}O{sub 8} spinel phase with nanometer particle size of the polymeric precursor method (Pechini) and characterization by means of thermal analysis (TG/DTA) X-ray diffraction (XRD), refined by the Rietveld method, BET, transmission electron microscopy (TEM), Raman and colorimetric coordinates. The pigment was obtained by heat treatment of 400 degree centigrade to 1000 degree centigrade after pyrolysis at 300 degree centigrade/1 h for removing the organic material. Li{sub 2}CoTi{sub 3}O{sub 8} desired spinel phase was obtained from 500 degree centigrade, and presenting stability nanometer to about 1.300 degree centigrade. Spinel green phase introduced at temperatures in the range of 400 degree centigrade and 500 degree centigrade, and 600 degree centigrade at temperatures between blue and 1000 degree centigrade. (Author)

  5. Strange particles

    International Nuclear Information System (INIS)

    Chinowsky, W.

    1989-01-01

    Work done in the mid 1950s at Brookhaven National Laboratory on strange particles is described. Experiments were done on the Cosmotron. The author describes his own and others' work on neutral kaons, lambda and theta particles and points out the theoretical gap between predictions and experimental findings. By the end of the decade, the theory of strange particles was better understood. (UK)

  6. Deliquescence and efflorescence of small particles.

    Science.gov (United States)

    McGraw, Robert; Lewis, Ernie R

    2009-11-21

    We examine size-dependent deliquescence/efflorescence phase transformation for particles down to several nanometers in size. Thermodynamic properties of inorganic salt particles, coated with aqueous solution layers of varying thickness and surrounded by vapor, are analyzed. A thin layer criterion (TLC) is introduced to define a limiting deliquescence relative humidity (RH(D)) for small particles. This requires: (1) equality of chemical potentials between salt in an undissolved core, and thin adsorbed solution layer, and (2) equality of chemical potentials between water in the thin layer and vapor phase. The usual bulk deliquescence conditions are recovered in the limit of large dry particle size. Nanosize particles are found to deliquesce at relative humidity just below the RH(D) on crossing a nucleation barrier, located at a critical solution layer thickness. This barrier vanishes precisely at the RH(D) defined by the TLC. Concepts and methods from nucleation theory including the kinetic potential, self-consistent nucleation theory, nucleation theorems, and the Gibbs dividing surface provide theoretical foundation and point to unifying features of small particle deliquescence/efflorescence processes. These include common thermodynamic area constructions, useful for interpretation of small particle water uptake measurements, and a common free-energy surface, with constant RH cross sections describing deliquescence and efflorescence related through the nucleation theorem.

  7. Nonmonotonic behaviour of superconducting critical temperature of Nb/CuNi bilayers with a nanometer range of layer thickness

    International Nuclear Information System (INIS)

    Morari, R.; Antropov, E.; Socrovisciuc, A.; Prepelitsa, A.; Zdravkov, V.I.; Tagirov, L.R.; Kupriyanov, M.Yu.; Sidorenko, A.S.

    2009-01-01

    Present work reports the result of the proximity effect investigation for superconducting Nb/CuNi-bilayers with the thickness of the ferromagnetic layer (Cu x Ni 1-x ) being in the sub-nanometer range. It was found a non-monotonic behavior of the critical temperature T c , i.e. its growth with the increasing of the ferromagnetic layer thickness dF, for the series of the samples with constant thickness of Nb layer, (d Nb = const). (authors)

  8. Nanometer-scale displacement measurement with high resolution using dual cavity Fabry-Pérot interferometer for biomimetic robots.

    Science.gov (United States)

    Lee, Jin-Hyuk; Kim, Dae-Hyun

    2014-10-01

    A sensor of a biomimetic robot has to measure very small environmental changes such as, nanometer scale strains or displacements. Fiber optic sensor can be also one of candidates for the biomimetic sensor because the sensor is like thread and the shape of the sensor is similar to muscle fiber. A fiber optic interferometer, which is an optical-based sensor, can measure displacement precisely, so such device has been widely studied for the measurement of displacement on a nanometer-scale. Especially, a Quadrature Phase-Shifted Fiber Fabry-Pérot interferometer (QPS-FFPI) uses phase-information for this measurement, allowing it to provide a precision result with high resolution. In theory, the QPS-FFPI generates two sinusoidal signals of which the phase difference should be 90 degrees for the exact measurement of the displacement. In order to guarantee the condition of the phase difference, the relative adjustment of the cavities of the optical fibers is required. However, with such precise adjustment it is very hard to fix the proper difference of the two cavities for quadrature-phase-shifting. In this paper, a dual-cavity FFPI is newly proposed to measure the displacement on a nanometer-scale with a specific type of signal processing. In the signal processing, a novel phase-compensation algorithm is applied to force the phase difference to be exactly 90 degrees without any physical adjustment. As a result, the paper shows that the phase-compensated dual-cavity FFPI can effectively measure nanometer-scale displacement with high resolution under dynamic conditions.

  9. Accelerator-based Single-shot Ultrafast Transmission Electron Microscope with Picosecond Temporal Resolution and Nanometer Spatial Resolution

    OpenAIRE

    Xiang, D.; Fu, F.; Zhang, J.; Huang, X.; Wang, L.; Wang, X.; Wan, W.

    2014-01-01

    We present feasibility study of an accelerator-based ultrafast transmission electron microscope (u-TEM) capable of producing a full field image in a single-shot with simultaneous picosecond temporal resolution and nanometer spatial resolution. We study key physics related to performance of u-TEMs, and discuss major challenges as well as possible solutions for practical realization of u-TEMs. The feasibility of u-TEMs is confirmed through simulations using realistic electron beam parameters. W...

  10. Nanometer and molecular materials: the greatness of the very tiny; Materiales manometricos y moleculares: la grandeza de lo infimo

    Energy Technology Data Exchange (ETDEWEB)

    Rincon, Marina [Centro de Investigacion en Energia (CIE) de la UNAM, Temixco, Morelos (Mexico)

    2010-07-01

    Some of the materials have been present in our lives for many years, and now appear with unique or improved properties by the fact that they can be manufactured in the nanometer scale; that is, a million times smaller than a millimeter and with geometries that include the nanodots, the nanotubes, the nanowires, to mention a few of them. The most popular is the titanium dioxide (Titania), known by many as the white pigment in paints, sunscreens, cosmetics and others for their null toxicity, low cost and high stability. Strictly speaking, these features are really applicable to the micrometric material (which is a thousand times larger than the nanometer) and it is still to be proven toxicity and stability of the nanometer materials; but it is a fact that the nanometer titania is very popular in a multitude of applications that have to do with catalysis, sensors, and energy conversion and storing. We will also deal with conductive polymers, which are molecular conjugated materials. [Spanish] Algunos de los materiales han estado presentes en nuestras vidas por muchos anos y ahora aparecen con propiedades unicas o mejoradas por el hecho de que se pueden fabricar en la escala de los nanometros; esto es, un millon de veces mas pequenos que un milimetro y con geometrias que comprenden los nanopuntos, los nanotubos, los nanoalambres, por mencionar algunas. El mas popular es el dioxido de titanio (titania), conocido por muchos como el pigmento blanco de las pinturas, filtros solares, cosmeticos y demas, por su nula toxicidad, bajo costo y gran estabilidad. Estrictamente hablando, estas caracteristicas son realmente aplicables al material micrometrico (que es mil veces mas grande que el nanometrico) y todavia esta por probarse la toxicidad y estabilidad de los nanomateriales; pero es un hecho que la titania nanometrica es muy popular en un sinfin de aplicaciones que tienen que ver con catalisis, sensores, y conversion y almacenamiento de energia. Hablaremos tambien de

  11. Passive micromechanical tags. An investigation into writing information at nanometer resolution on micrometer size objects

    International Nuclear Information System (INIS)

    Schmieder, R.W.; Bastasz, R.J.

    1995-01-01

    The authors have completed a 3-year study of the technology related to the development of micron-sized passive micromechanical tags. The project was motivated by the discovery in 1990 by the present authors that low energy, high charge state ions (e.g., Xe +44 ) can produce nanometer-size damage sites on solid surfaces, and the realization that a pattern of these sites represents information. It was envisioned that extremely small, chemically inert, mechanical tags carrying a large label could be fabricated for a variety of applications, including tracking of controlled substances, document verification, process control, research, and engineering. Potential applications exist in the data storage, chemical, food, security, and other industries. The goals of this project were fully accomplished, and they are fully documented here. The work was both experimental and developmental. Most of the experimental effort was a search for appropriate tag materials. Several good materials were found, and the upper limits of information density were determined (ca. 10 12 bit/cm 2 ). Most of the developmental work involved inventing systems and strategies for using these tags, and compiling available technologies for implementing them. The technology provided herein is application-specific: first, the application must be specified, then the tag can be developed for it. The project was not intended to develop a single tag for a single application or for all possible applications. Rather, it was meant to provide the enabling technology for fabricating tags for a range of applications. The results of this project provide sufficient information to proceed directly with such development

  12. Passive micromechanical tags. An investigation into writing information at nanometer resolution on micrometer size objects

    Energy Technology Data Exchange (ETDEWEB)

    Schmieder, R.W.; Bastasz, R.J.

    1995-01-01

    The authors have completed a 3-year study of the technology related to the development of micron-sized passive micromechanical tags. The project was motivated by the discovery in 1990 by the present authors that low energy, high charge state ions (e.g., Xe{sup +44}) can produce nanometer-size damage sites on solid surfaces, and the realization that a pattern of these sites represents information. It was envisioned that extremely small, chemically inert, mechanical tags carrying a large label could be fabricated for a variety of applications, including tracking of controlled substances, document verification, process control, research, and engineering. Potential applications exist in the data storage, chemical, food, security, and other industries. The goals of this project were fully accomplished, and they are fully documented here. The work was both experimental and developmental. Most of the experimental effort was a search for appropriate tag materials. Several good materials were found, and the upper limits of information density were determined (ca. 10{sup 12} bit/cm{sup 2}). Most of the developmental work involved inventing systems and strategies for using these tags, and compiling available technologies for implementing them. The technology provided herein is application-specific: first, the application must be specified, then the tag can be developed for it. The project was not intended to develop a single tag for a single application or for all possible applications. Rather, it was meant to provide the enabling technology for fabricating tags for a range of applications. The results of this project provide sufficient information to proceed directly with such development.

  13. Wetting at the nanometer scale: effects of long-range forces and substrate heterogeneities

    International Nuclear Information System (INIS)

    Checco, Antonio

    2003-01-01

    Wetting phenomena on the nano-scale remain poorly understood in spite of their growing theoretical and practical interest. In this context, the present work aimed at studying partial wetting of nanometer-sized alkane droplets on 'model' surfaces build by self-assembly of organic monolayers. For this purpose a novel technique, based on 'noncontact' Atomic Force Microscopy (AFM), has been developed to image, with minimal artefacts, drops of adjustable size directly condensed on so- lid surfaces. We have thus shown that contact angle of alkanes, wetting a weakly heterogeneous, silanized substrate, noticeably decreases from its macroscopic value for droplets sizes in the submicron range. The line tension, arising in this case from purely dispersive long-range interactions between the liquid and the substrate, is theoretically too weak to be responsible for the observed effect. Therefore we have supposed that contact angle is affected by mesoscopic chemical heterogeneities of the substrate whenever the droplets size becomes sufficiently small. This scenario has been supported by numerical simulations based on a simplified model of the spatial distribution of surface defects. Similar experiments, performed on different substrates (monolayers made of alkane-thiols self-assembled on gold and of alkyl chains covalently bound onto a silicon surface), have also shown that wetting on small scales is strongly affected by minimal physical and chemical surface heterogeneities. Finally, to provide further examples of the potential of the above mentioned AFM technique, we have studied the wettability of nano-structured surfaces and the local wetting properties of hair. (author) [fr

  14. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices.

    Science.gov (United States)

    Grosse, Kyle L; Pop, Eric; King, William P

    2014-09-01

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K(-1). This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  15. Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Grosse, Kyle L. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Pop, Eric [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); King, William P., E-mail: wpk@illinois.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Departments of Electrical and Computer Engineering and Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2014-09-15

    This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 μV K{sup −1}. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

  16. Formation and surface strengthening of nano-meter embedded phases during high energy Ti implanted and annealed steel

    International Nuclear Information System (INIS)

    Zhang Tonghe; Wu Yuguang; Cui Ping; Wang Ping

    1999-12-01

    Observation of transmission electron microscope indicated that the phase of FeTi 2 with 3.5-20 nm in diameter is embedded in high energy Ti implanted layer. It's average diameter is 8 nm. The nano-meter phases were embedded among dislocations and grain boundary in Ti implanted steel at 400 degree C. The wear resistance has been improved. The embedded structure can be changed obviously after annealing. The structure has been changed slightly after annealing at annealing temperature raging from 350 to 500 degree C, however, the hardness and wear resistance of implanted layer increased greatly. The maximum of hardness is obtained when the sample was annealed at 500 degree C for 20 min. It can be seen that the strengthening of implanted layer has enhanced by annealing indeed. The grain boundary and dislocations have disappeared; the diameter of nano-meter phases increased from 10 nm to 15 nm after annealing at temperature of 750 degree C and 1000 degree respectively. The average densities of nano-meter phases are 8.8 x 10 10 /cm 2 and 6.5 x 10 10 /cm 2 respectively for both of annealing temperature. The hardness decreased obviously when the annealing temperature is greater than 750 degree C

  17. Electromagnetic scattering by a polydispersion of small charged cosmic dust particles

    Directory of Open Access Journals (Sweden)

    M. Kocifaj

    2011-09-01

    Full Text Available Some recent studies on extended red emissions suggest the presence of very small dust particles in the Universe. The sizes of these particles vary from 1 nm to some tens of nanometers, thus situating them deeply in the Rayleigh region if computations are made for visible or near infrared. The optical response of such particles can be a function of the surface charge. In this study we analyse the effect of surface electric potential on the total optical thickness and scattering phase function of the cosmic dust particles. The results are compared with those obtained for electrically neutral dust.

  18. CRA Grade Inflation

    OpenAIRE

    Kenneth H. Thomas

    2000-01-01

    Community Reinvestment Act of 1977 (CRA) ratings and performance evaluations are the only bank and thrift exam findings disclosed by financial institution regulators. Inflation of CRA ratings has been alleged by community activists for two decades, but there has been no quantification or empirical investigation of grade inflation. Using a unique grade inflation methodology on actual ratings and evaluation data for 1,407 small banks and thrifts under the revised CRA regulations, this paper con...

  19. Functionally graded materials

    CERN Document Server

    Mahamood, Rasheedat Modupe

    2017-01-01

    This book presents the concept of functionally graded materials as well as their use and different fabrication processes. The authors describe the use of additive manufacturing technology for the production of very complex parts directly from the three dimension computer aided design of the part by adding material layer after layer. A case study is also presented in the book on the experimental analysis of functionally graded material using laser metal deposition process.

  20. Single-Molecule Fluorescence Microscopy Reveals Local Diffusion Coefficients in the Pore Network of an Individual Catalyst Particle

    NARCIS (Netherlands)

    Hendriks, Frank|info:eu-repo/dai/nl/412642697; Meirer, Florian; Kubarev, Alexey V.; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Roeffaers, Maarten B J; Vogt, Eelco T. C.|info:eu-repo/dai/nl/073717398; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2017-01-01

    We used single-molecule fluorescence microscopy to study self-diffusion of a feedstock-like probe molecule with nanometer accuracy in the macropores of a micrometer-sized, real-life fluid catalytic cracking (FCC) particle. Movies of single fluorescent molecules allowed their movement through the

  1. Particle therapy

    Energy Technology Data Exchange (ETDEWEB)

    Raju, M.R.

    1993-09-01

    Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics.

  2. Particle therapy

    International Nuclear Information System (INIS)

    Raju, M.R.

    1993-01-01

    Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics

  3. Particle cosmology

    CERN Multimedia

    CERN. Geneva

    2007-01-01

    The understanding of the Universe at the largest and smallest scales traditionally has been the subject of cosmology and particle physics, respectively. Studying the evolution of the Universe connects today's large scales with the tiny scales in the very early Universe and provides the link between the physics of particles and of the cosmos. This series of five lectures aims at a modern and critical presentation of the basic ideas, methods, models and observations in today's particle cosmology.

  4. Particle physics

    International Nuclear Information System (INIS)

    Kamal, Anwar

    2014-01-01

    Provides step-by-step derivations. Contains numerous tables and diagrams. Supports learning and teaching with numerous worked examples, questions and problems with answers. Sketches also the historical development of the subject. This textbook teaches particle physics very didactically. It supports learning and teaching with numerous worked examples, questions and problems with answers. Numerous tables and diagrams lead to a better understanding of the explanations. The content of the book covers all important topics of particle physics: Elementary particles are classified from the point of view of the four fundamental interactions. The nomenclature used in particle physics is explained. The discoveries and properties of known elementary particles and resonances are given. The particles considered are positrons, muon, pions, anti-protons, strange particles, neutrino and hadrons. The conservation laws governing the interactions of elementary particles are given. The concepts of parity, spin, charge conjugation, time reversal and gauge invariance are explained. The quark theory is introduced to explain the hadron structure and strong interactions. The solar neutrino problem is considered. Weak interactions are classified into various types, and the selection rules are stated. Non-conservation of parity and the universality of the weak interactions are discussed. Neutral and charged currents, discovery of W and Z bosons and the early universe form important topics of the electroweak interactions. The principles of high energy accelerators including colliders are elaborately explained. Additionally, in the book detectors used in nuclear and particle physics are described. This book is on the upper undergraduate level.

  5. Magnetic particles

    Science.gov (United States)

    Chang, Manchium (Inventor); Colvin, Michael S. (Inventor)

    1989-01-01

    Magnetic polymer particles are formed by swelling porous, polymer particles and impregnating the particles with an aqueous solution of precursor magnetic metal salt such as an equimolar mixture of ferrous chloride and ferric chloride. On addition of a basic reagent such as dilute sodium hydroxide, the metal salts are converted to crystals of magnetite which are uniformly contained througout the pores of the polymer particle. The magnetite content can be increased and neutral buoyancy achieved by repetition of the impregnaton and neutralization steps to adjust the magnetite content to a desired level.

  6. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Colliex, Christian, E-mail: christian.colliex@u-psud.fr; Kociak, Mathieu; Stéphan, Odile

    2016-03-15

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  7. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale.

    Science.gov (United States)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-03-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  8. Long-term irradiation effects on reactor-pressure vessel steels. Investigations on the nanometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Arne

    2017-06-01

    The exposure of reactor pressure vessel (RPV) steels to neutron irradiation gives rise to irradiation-enhanced diffusion, a rearrangement of solute atoms and, consequently, a degradation of the mechanical properties. The increasing age of existing nuclear power plants raises new questions specific to long-term operation. Two of them are addressed in this thesis: flux effects and the late-blooming effect. Can low-flux irradiations up to a given fluence be reproduced by more rapid high-flux irradiations up to the same fluence? Can the irradiation response of RPV steels be extrapolated to higher fluences or are there unexpected ''late-blooming'' effects. Small-angle neutron scattering (SANS), atom-probe tomography (APT) and Vickers-hardness testing were applied. A novel Monte-Carlo based fitting algorithm for SANS data was implemented in order to derive statistically reliable characteristics of irradiation-induced solute-atom clusters. APT was applied in selected cases to gain additional information on the composition and the shape of clusters. Vickers hardness testing was performed on the SANS samples to link the nanometer-scale changes to irradiation hardening. The investigations on flux effects show that clusters forming upon high-flux irradiation are smaller and tend to have a higher number density compared to low-flux irradiations at a given neutron fluence. The measured flux dependence of the cluster-size distribution is consistent with the framework of deterministic growth (but not with coarsening) in combination with radiation-enhanced diffusion. Since the two effects on cluster-size and volume fraction partly cancel each other out, no significant effect on the hardening is observed. The investigations of a possible late-blooming effect indicate that the very existence (yes or no) of such an effect depends on the irradiation conditions. Irradiations at lower fluxes and a lower temperature (255 C) give rise to a significant increase of the

  9. Electron Energy Loss Spectroscopy imaging of surface plasmons at the nanometer scale

    International Nuclear Information System (INIS)

    Colliex, Christian; Kociak, Mathieu; Stéphan, Odile

    2016-01-01

    Since their first realization, electron microscopes have demonstrated their unique ability to map with highest spatial resolution (sub-atomic in most recent instruments) the position of atoms as a consequence of the strong scattering of the incident high energy electrons by the nuclei of the material under investigation. When interacting with the electron clouds either on atomic orbitals or delocalized over the specimen, the associated energy transfer, measured and analyzed as an energy loss (Electron Energy Loss Spectroscopy) gives access to analytical properties (atom identification, electron states symmetry and localization). In the moderate energy-loss domain (corresponding to an optical spectral domain from the infrared (IR) to the rather far ultra violet (UV), EELS spectra exhibit characteristic collective excitations of the rather-free electron gas, known as plasmons. Boundary conditions, such as surfaces and/or interfaces between metallic and dielectric media, generate localized surface charge oscillations, surface plasmons (SP), which are associated with confined electric fields. This domain of research has been extraordinarily revived over the past few years as a consequence of the burst of interest for structures and devices guiding, enhancing and controlling light at the sub-wavelength scale. The present review focuses on the study of these surface plasmons with an electron microscopy-based approach which associates spectroscopy and mapping at the level of a single and well-defined nano-object, typically at the nanometer scale i.e. much improved with respect to standard, and even near-field, optical techniques. After calling to mind some early studies, we will briefly mention a few basic aspects of the required instrumentation and associated theoretical tools to interpret the very rich data sets recorded with the latest generation of (Scanning)TEM microscopes. The following paragraphs will review in more detail the results obtained on simple planar and

  10. Nanometer-thin TiO2 enhances skeletal muscle cell phenotype and behavior

    Directory of Open Access Journals (Sweden)

    Ishizaki K

    2011-10-01

    Full Text Available Ken Ishizaki*, Yoshihiko Sugita*, Fuminori Iwasa, Hajime Minamikawa, Takeshi Ueno, Masahiro Yamada, Takeo Suzuki, Takahiro OgawaLaboratory for Bone and Implant Sciences, The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA*Authors contributed equally to this workBackground: The independent role of the surface chemistry of titanium in determining its biological properties is yet to be determined. Although titanium implants are often in contact with muscle tissue, the interaction of muscle cells with titanium is largely unknown. This study tested the hypotheses that the surface chemistry of clinically established microroughened titanium surfaces could be controllably varied by coating with a minimally thin layer of TiO2 (ideally pico-to-nanometer in thickness without altering the existing topographical and roughness features, and that the change in superficial chemistry of titanium is effective in improving the biological properties of titanium.Methods and results: Acid-etched microroughened titanium surfaces were coated with TiO2 using slow-rate sputter deposition of molten TiO2 nanoparticles. A TiO2 coating of 300 pm to 6.3 nm increased the surface oxygen on the titanium substrates in a controllable manner, but did not alter the existing microscale architecture and roughness of the substrates. Cells derived from rat skeletal muscles showed increased attachment, spread, adhesion strength, proliferation, gene expression, and collagen production at the initial and early stage of culture on 6.3 nm thick TiO2-coated microroughened titanium surfaces compared with uncoated titanium surfaces.Conclusion: Using an exemplary slow-rate sputter deposition technique of molten TiO2 nanoparticles, this study demonstrated that titanium substrates, even with microscale roughness, can be sufficiently chemically modified to

  11. Sub-nanometer emittance monitor for high brightness synchrotron radiation source

    International Nuclear Information System (INIS)

    Nakajima, K.

    1991-01-01

    Method of measuring a very small beam emittance in electron storage rings is presented. The monitor can sense an intrinsic emittance of beam particles by detecting the angular distribution of Compton scatterings of laser photons on beam electrons. It is possible to achieve measurement resolution smaller than 10 -9 m-rad without difficulty. (author)

  12. Particle accelerator

    International Nuclear Information System (INIS)

    Ress, R.I.

    1976-01-01

    Charged particles are entrained in a predetermined direction, independent of their polarity, in a circular orbit by a magnetic field rotating at high speed about an axis in a closed cylindrical or toroidal vessel. The field may be generated by a cylindrical laser structure, whose beam is polygonally reflected from the walls of an excited cavity centered on the axis, or by high-frequency energization of a set of electromagnets perpendicular to the axis. In the latter case, a separate magnetostatic axial field limits the orbital radius of the particles. These rotating and stationary magnetic fields may be generated centrally or by individual magnets peripherally spaced along its circular orbit. Chemical or nuclear reactions can be induced by collisions between the orbiting particles and an injected reactant, or by diverting high-speed particles from one doughnut into the path of counterrotating particles in an adjoining doughnut

  13. Contractions from grading

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2018-04-01

    We note that large classes of contractions of algebras that arise in physics can be understood purely algebraically via identifying appropriate Zm-gradings (and their generalizations) on the parent algebra. This includes various types of flat space/Carroll limits of finite and infinite dimensional (A)dS algebras, as well as Galilean and Galilean conformal algebras. Our observations can be regarded as providing a natural context for the Grassmann approach of Krishnan et al. [J. High Energy Phys. 2014(3), 36]. We also introduce a related notion, which we call partial grading, that arises naturally in this context.

  14. Mapping the Diffusion Potential of a Reconstructed Au(111) Surface at Nanometer Scale with 2D Molecular Gas

    International Nuclear Information System (INIS)

    Yan Shi-Chao; Xie Nan; Gong Hui-Qi; Guo Yang; Shan Xin-Yan; Lu Xing-Hua; Sun Qian

    2012-01-01

    The adsorption and diffusion behaviors of benzene molecules on an Au(111) surface are investigated by low-temperature scanning tunneling microscopy. A herringbone surface reconstruction of the Au(111) surface is imaged with atomic resolution, and significantly different behaviors are observed for benzene molecules adsorbed on step edges and terraces. The electric field induced modification in the molecular diffusion potential is revealed with a 2D molecular gas model, and a new method is developed to map the diffusion potential over the reconstructed Au(111) surface at the nanometer scale. (condensed matter: structure, mechanical and thermal properties)

  15. Luminescent Oxygen Gas Sensors Based on Nanometer-Thick Hybrid Films of Iridium Complexes and Clay Minerals

    Directory of Open Access Journals (Sweden)

    Hisako Sato

    2014-01-01

    Full Text Available The use of Ir(III complexes in photo-responsive molecular devices for oxygen gas sensing is reviewed. Attention is focused on the immobilization of Ir(III complexes in organic or inorganic host materials such as polymers, silica and clays in order to enhance robustness and reliability. Our recent works on constructing nanometer-thick films comprised of cyclometalated cationic Ir(III complexes and clay minerals are described. The achievement of multi-emitting properties in response to oxygen pressure is demonstrated.

  16. Accelerator-based single-shot ultrafast transmission electron microscope with picosecond temporal resolution and nanometer spatial resolution

    Science.gov (United States)

    Xiang, D.; Fu, F.; Zhang, J.; Huang, X.; Wang, L.; Wang, X.; Wan, W.

    2014-09-01

    We present feasibility study of an accelerator-based ultrafast transmission electron microscope (u-TEM) capable of producing a full field image in a single-shot with simultaneous picosecond temporal resolution and nanometer spatial resolution. We study key physics related to performance of u-TEMs and discuss major challenges as well as possible solutions for practical realization of u-TEMs. The feasibility of u-TEMs is confirmed through simulations using realistic electron beam parameters. We anticipate that u-TEMs with a product of temporal and spatial resolution beyond 10-19 ms will open up new opportunities in probing matter at ultrafast temporal and ultrasmall spatial scales.

  17. Endangered Animals. Second Grade.

    Science.gov (United States)

    Popp, Marcia

    This second grade teaching unit centers on endangered animal species around the world. Questions addressed are: What is an endangered species? Why do animals become extinct? How do I feel about the problem? and What can I do? Students study the definition of endangered species and investigate whether it is a natural process. They explore topics…

  18. Calculating Student Grades.

    Science.gov (United States)

    Allswang, John M.

    1986-01-01

    This article provides two short microcomputer gradebook programs. The programs, written in BASIC for the IBM-PC and Apple II, provide statistical information about class performance and calculate grades either on a normal distribution or based on teacher-defined break points. (JDH)

  19. Grades as Information

    Science.gov (United States)

    Grant, Darren

    2007-01-01

    We determine how much observed student performance in microeconomics principles can be attributed, inferentially, to three kinds of student academic "productivity," the instructor, demographics, and unmeasurables. The empirical approach utilizes an ordered probit model that relates student performance in micro to grades in prior…

  20. First Grade Baseline Evaluation

    Science.gov (United States)

    Center for Innovation in Assessment (NJ1), 2013

    2013-01-01

    The First Grade Baseline Evaluation is an optional tool that can be used at the beginning of the school year to help teachers get to know the reading and language skills of each student. The evaluation is composed of seven screenings. Teachers may use the entire evaluation or choose to use those individual screenings that they find most beneficial…

  1. The Fifth Grade Classroom.

    Science.gov (United States)

    Hartman, Michael; And Others

    An interdisciplinary design project report investigates the relationship of the fifth grade educational facility to the student and teacher needs in light of human and environmental factors. The classroom, activity and teaching spaces are analyzed with regard to the educational curriculum. Specifications and design criteria concerning equipment…

  2. Cutting Class Harms Grades

    Science.gov (United States)

    Taylor, Lewis A., III

    2012-01-01

    An accessible business school population of undergraduate students was investigated in three independent, but related studies to determine effects on grades due to cutting class and failing to take advantage of optional reviews and study quizzes. It was hypothesized that cutting classes harms exam scores, attending preexam reviews helps exam…

  3. Environmental Transport of Plutonium: Biogeochemical Processes at Femtomolar Concentrations and Nanometer Scales

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Annie B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-10-05

    The major challenge in predicting the mobility and transport of plutonium (Pu) is determining the dominant geochemical processes that control its behavior in the subsurface. The reaction chemistry of Pu (i.e., aqueous speciation, solubility, sorptivity, redox chemistry, and affinity for colloidal particles, both abiotic and microbially mediated) is particularly complicated. It is generally thought that due to its low solubility and high sorptivity, Pu migration in the environment occurs only when facilitated by transport on particulate matter (i.e., colloidal particles). Despite the recognized importance of colloid-facilitated transport of Pu, very little is known about the geochemical and biochemical mechanisms controlling Pu-colloid formation and association, particularly at femtomolar Pu concentrations observed at DOE sites.

  4. New method for introducing nanometer flux pinning centers into single domain YBCO bulk superconductors

    International Nuclear Information System (INIS)

    Yang, W.M.; Wang, Miao

    2013-01-01

    Highlights: • Single domain YBCO bulks with Bi 2 O 3 additions fabricated by TSIG process. • Nanoscale Y 2 Ba 4 CuBiOx(YBi2411) particles introduced by Bi 2 O 3 additions. • The YBi2411 particles are about 150 nm, can act as effective flux pinning centers. • The optimal addition of Bi 2 O 3 is 0.7wt% to achieve higher levitation force. • The result is helpful to improve the quality of REBCO bulk superconductors. -- Abstract: Single domain YBCO superconductors with different additions of Bi 2 O 3 have been fabricated by top seeded infiltration and growth process (TSIG). The effect of Bi 2 O 3 additions on the growth morphology, microstructure and levitation force of the YBCO bulk superconductor has been investigated. The results indicate that single domain YBCO superconductors can be fabricated with the additions of Bi 2 O 3 less than 2 wt%; Bi 2 O 3 can be reacted with Y 2 BaCuO 5 and liquid phase and finally form Y 2 Ba 4 CuBiO x (YBi2411) nanoscale particles; the size of the YBi2411 particles is about 100 nm, which can act as effective flux pinning centers. It is also found that the levitation force of single domain YBCO bulks is increasing from 13 N to 34 N and decreasing to 11 N with the increasing of Bi 2 O 3 addition from 0.1 wt% to 0.7 wt% and 2 wt%. This result is helpful for us to improve the physical properties of REBCO bulk superconductors

  5. Evolution of particle composition in CLOUD nucleation experiments

    Directory of Open Access Journals (Sweden)

    H. Keskinen

    2013-06-01

    Full Text Available Sulphuric acid, ammonia, amines, and oxidised organics play a crucial role in nanoparticle formation in the atmosphere. In this study, we investigate the composition of nucleated nanoparticles formed from these compounds in the CLOUD (Cosmics Leaving Outdoor Droplets chamber experiments at CERN (Centre européen pour la recherche nucléaire. The investigation was carried out via analysis of the particle hygroscopicity, ethanol affinity, oxidation state, and ion composition. Hygroscopicity was studied by a hygroscopic tandem differential mobility analyser and a cloud condensation nuclei counter, ethanol affinity by an organic differential mobility analyser and particle oxidation level by a high-resolution time-of-flight aerosol mass spectrometer. The ion composition was studied by an atmospheric pressure interface time-of-flight mass spectrometer. The volume fraction of the organics in the particles during their growth from sizes of a few nanometers to tens of nanometers was derived from measured hygroscopicity assuming the Zdanovskii–Stokes–Robinson relationship, and compared to values gained from the spectrometers. The ZSR-relationship was also applied to obtain the measured ethanol affinities during the particle growth, which were used to derive the volume fractions of sulphuric acid and the other inorganics (e.g. ammonium salts. In the presence of sulphuric acid and ammonia, particles with a mobility diameter of 150 nm were chemically neutralised to ammonium sulphate. In the presence of oxidation products of pinanediol, the organic volume fraction of freshly nucleated particles increased from 0.4 to ~0.9, with an increase in diameter from 2 to 63 nm. Conversely, the sulphuric acid volume fraction decreased from 0.6 to 0.1 when the particle diameter increased from 2 to 50 nm. The results provide information on the composition of nucleated aerosol particles during their growth in the presence of various combinations of sulphuric acid

  6. Particle detectors

    CERN Document Server

    Hilke, Hans Jürgen

    1992-01-01

    We shall discuss the principles of the main techniques applied to particle detection (including front-end electronics), the construction and performance of some of the devices presently in operation and a few ideas on future developments.

  7. Viscous properties of ferrofluids containing both micrometer-size magnetic particles and fine needle-like particles

    Energy Technology Data Exchange (ETDEWEB)

    Ido, Yasushi, E-mail: ido.yasushi@nitech.ac.jp [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Nishida, Hitoshi [Department of Electrical and Control Systems Engineering, National Institute of Technology, Toyama College, 13 Hongo-cho, Toyama (Japan); Iwamoto, Yuhiro [Department of Electric and Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya (Japan); Yokoyama, Hiroki [KYB Corporation, 2-4-1 Hamamatsu-cho, Minato-ku, Tokyo (Japan)

    2017-06-01

    Ferrofluids containing both micrometer-size spherical magnetic particles and nanometer-size needle-like nonmagnetic hematite particles were newly produced. Average length of long axis of the needle-like nonmagnetic particles was 194 nm and the aspect ratio was 8.3. Shear stress and viscosity were measured using the rheometer with the additional equipment for viscosity measurements in the presence of magnetic field. When the total volume fraction of particles in the fluid is constant (0.30), there is the specific mixing ratio of the particles to increase viscosity of the fluid drastically in the absence of magnetic field due to the percolation phenomenon. The fluid of the specific mixing ratio shows solid-like behavior even in the absence of magnetic field. Mixing the needle-like nonmagnetic particles causes strong yield stress and strong viscous force in the presence of magnetic field. - Highlights: • Viscous properties of new magnetic functional fluids were studied experimentally. • The new fluids contain spherical magnetic particles and needle-like particles. • Percolation occurs in the fluid of specific mixing ratio of particles without field. • The fluid of the specific mixing ratio behaves like solid without field. • Mixing needle-like particles causes strong yield stress of the fluid in the field.

  8. Sodium Caseinate-Carrageenan Biopolymeric Nanocomplexes as a Carrier of Vitamin D: Study of Complex Formation, Particles Size and Encapsulation Efficiency

    Directory of Open Access Journals (Sweden)

    Maryam Khoshmanzar

    2014-04-01

    Full Text Available The protein-polysaccharide complex-based nanocapsule is one type of polymeric nanocarrier which can be potentially useful for encapsulation of hydrophobic nutraceuticals. In this research, caseinate-carrageenan complex was used for encapsulation of vitamin D. The complex formation between caseinate and carrageenan was carried out by lowering the pH under isoelectric point of protein. The Fourier transform infrared spectroscopy (FTIR and differential scanning colorimetry (DSC confirmed complex formation between carrageenan, caseinate and vitamin D. The particle size of 1% caseinate particles was in the range of 150-300 nanometer and by addition of vitamin D the particle size increased to 450-750 nanometer. Moreover, carrageenan of all concentrations (at constant concentration of caseinate (1% and pH4.9 resulted in lower particle size below 100 nanometer. The stability of caseinate and its complex formation with carrageenan showed that encapsulation was achieved at 45% efficiency and also vitamin D stability (during 5 days storage was higher in nanocomplex compared to pure caseinate particles (60-63% compared to 53%. The complex formation between caseinate and carrageenan was carried out by pH decreasing under isoelectric point of protein. The FTIR and DSC confirmed complex formation between carrageenan, caseinate and vitamin D. The particle size of caseinate 1% particles were in the range of 150 -300 nanometer and with adding vitamin D, particle size increased to 450-750 nanometer. Moreover, adding carrageenan at all used concentration (at constant concentration of caseinate (1% and pH4.9 resulted in reduced particle size to less than 100 nanometer and vitamin D stability (during 5 days storage was higher (60-63% in nanocomplex compared to pure caseinate particles (53%.The protein-polysaccharide complex based nanocapsule is one type of the polymeric nanocarriers which can potentially be used for encapsulation of hydrophobic nutraceuticals. In

  9. Auroral particles

    International Nuclear Information System (INIS)

    Evans, D.S.

    1987-01-01

    The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries

  10. Magnetic particles as powerful purification tool for high sensitive mass spectrometric screening procedures.

    Science.gov (United States)

    Peter, Jochen F; Otto, Angela M

    2010-02-01

    The effective isolation and purification of proteins from biological fluids is the most crucial step for a successful protein analysis when only minute amounts are available. While conventional purification methods such as dialysis, ultrafiltration or protein precipitation often lead to a marked loss of protein, SPE with small-sized particles is a powerful alternative. The implementation of particles with superparamagnetic cores facilitates the handling of those particles and allows the application of particles in the nanometer to low micrometer range. Due to the small diameters, magnetic particles are advantageous for increasing sensitivity when using subsequent MS analysis or gel electrophoresis. In the last years, different types of magnetic particles were developed for specific protein purification purposes followed by analysis or screening procedures using MS or SDS gel electrophoresis. In this review, the use of magnetic particles for different applications, such as, the extraction and analysis of DNA/RNA, peptides and proteins, is described.

  11. Elementary particles and particle interactions

    International Nuclear Information System (INIS)

    Bethge, K.; Schroeder, U.E.

    1986-01-01

    This book is a textbook for an introductory course of elementary particle physics. After a general introduction the symmetry principles governing the interactions of elementary particles are discussed. Then the phenomenology of the electroweak and strong interactions are described together with a short introduction to the Weinberg-Salam theory respectively to quantum chromodynamics. Finally a short outlook is given to grand unification with special regards to SU(5) and cosmology in the framework of the current understanding of the fundamental principles of nature. In the appendix is a table of particle properties and physical constants. (HSI) [de

  12. Pseudopotential-based electron quantum transport: Theoretical formulation and application to nanometer-scale silicon nanowire transistors

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Jingtian, E-mail: jingtian.fang@utdallas.edu; Vandenberghe, William G.; Fu, Bo; Fischetti, Massimo V. [Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080 (United States)

    2016-01-21

    We present a formalism to treat quantum electronic transport at the nanometer scale based on empirical pseudopotentials. This formalism offers explicit atomistic wavefunctions and an accurate band structure, enabling a detailed study of the characteristics of devices with a nanometer-scale channel and body. Assuming externally applied potentials that change slowly along the electron-transport direction, we invoke the envelope-wavefunction approximation to apply the open boundary conditions and to develop the transport equations. We construct the full-band open boundary conditions (self-energies of device contacts) from the complex band structure of the contacts. We solve the transport equations and present the expressions required to calculate the device characteristics, such as device current and charge density. We apply this formalism to study ballistic transport in a gate-all-around (GAA) silicon nanowire field-effect transistor with a body-size of 0.39 nm, a gate length of 6.52 nm, and an effective oxide thickness of 0.43 nm. Simulation results show that this device exhibits a subthreshold slope (SS) of ∼66 mV/decade and a drain-induced barrier-lowering of ∼2.5 mV/V. Our theoretical calculations predict that low-dimensionality channels in a 3D GAA architecture are able to meet the performance requirements of future devices in terms of SS swing and electrostatic control.

  13. Development of a sub-nanometer positioning device: combining a new linear motor with linear motion ball guide ways

    International Nuclear Information System (INIS)

    Otsuka, J; Tanaka, T; Masuda, I

    2010-01-01

    A new type of linear motor described in this note has some advantages compared with conventional motors. The attractive magnetic force between the stator (permanent magnets) and mover (armature) is diminished almost to zero. The efficiency is better because the magnetic flux leakage is very small, the size of motor is smaller and detent (force ripple) is smaller than for conventional motors. Therefore, we think that this motor is greatly suitable for ultra-precision positioning as an actuator. An ultra-precision positioning device using this motor and linear motion ball guide ways is newly developed by making the device very rigid and using a suitable control method. Moreover, the positioning performance is evaluated by a positioning resolution, and deviation and dispersion errors. As a result of repeated step response tests, the positioning resolution is 0.3 nm, with the deviation error and dispersion error (3σ) being sub-nanometer. Consequently, the positioning device achieves sub-nanometer positioning. (technical design note)

  14. A new capacitive long-range displacement nanometer sensor with differential sensing structure based on time-grating

    Science.gov (United States)

    Yu, Zhicheng; Peng, Kai; Liu, Xiaokang; Pu, Hongji; Chen, Ziran

    2018-05-01

    High-precision displacement sensors, which can measure large displacements with nanometer resolution, are key components in many ultra-precision fabrication machines. In this paper, a new capacitive nanometer displacement sensor with differential sensing structure is proposed for long-range linear displacement measurements based on an approach denoted time grating. Analytical models established using electric field coupling theory and an area integral method indicate that common-mode interference will result in a first-harmonic error in the measurement results. To reduce the common-mode interference, the proposed sensor design employs a differential sensing structure, which adopts a second group of induction electrodes spatially separated from the first group of induction electrodes by a half-pitch length. Experimental results based on a prototype sensor demonstrate that the measurement accuracy and the stability of the sensor are substantially improved after adopting the differential sensing structure. Finally, a prototype sensor achieves a measurement accuracy of  ±200 nm over the full 200 mm measurement range of the sensor.

  15. Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

    International Nuclear Information System (INIS)

    Dong Dianbo; Li Peijun; Li Xiaojun; Zhao Qing; Zhang Yinqiu; Jia Chunyun; Li Peng

    2010-01-01

    Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

  16. 2D surface optical lattice formed by plasmon polaritons with application to nanometer-scale molecular deposition.

    Science.gov (United States)

    Yin, Yanning; Xu, Supeng; Li, Tao; Yin, Yaling; Xia, Yong; Yin, Jianping

    2017-08-10

    Surface plasmon polaritons, due to their tight spatial confinement and high local intensity, hold great promises in nanofabrication which is beyond the diffraction limit of conventional lithography. Here, we demonstrate theoretically the 2D surface optical lattices based on the surface plasmon polariton interference field, and the potential application to nanometer-scale molecular deposition. We present the different topologies of lattices generated by simple configurations on the substrate. By explicit theoretical derivations, we explain their formation and characteristics including field distribution, periodicity and phase dependence. We conclude that the topologies can not only possess a high stability, but also be dynamically manipulated via changing the polarization of the excitation laser. Nanometer-scale molecular deposition is simulated with these 2D lattices and discussed for improving the deposition resolution. The periodic lattice point with a width resolution of 33.2 nm can be obtained when the fullerene molecular beam is well-collimated. Our study can offer a superior alternative method to fabricate the spatially complicated 2D nanostructures, with the deposition array pitch serving as a reference standard for accurate and traceable metrology of the SI length standard.

  17. In vivo MR imaging of nanometer magnetically labeled bone marrow stromal cells transplanted via portal vein in rat liver

    International Nuclear Information System (INIS)

    Wang Ping; Wang Jianhua; Yan Zhiping; Hu Meiyu; Xu Pengju; Zhou Meiling; Ya Fuhua; Fan Sheung-tat; Luk John-m

    2006-01-01

    Objective: To evaluate in vivo magnetic resonance imaging with a conventional 1.5-T system for tracking of intra-portal vein transplantation nanometer magnetically labeled BMSCs in rat liver. Methods: BMSCs were isolated from 5 SD rats bone marrow with the density gradient centrifugation method. Then BMSCs were labeled with nanometer superpara-magnetic iron oxide and transfection agent. Cell labeling efficiency was assessed with determination of the percentage of Peris Prussian blue stain. Then BMSCs transplanted into normal rats' livers via portal vein. The receipts were divided into 5 groups ,including sham control,2 h ,3 d,7 d and 2 w after transplantation. Follow-up serial T 1 WI,T 2 WI and T 2 * -weighted gradient- echo MR imaging were performed at 1.5 T MRI system. MR imaging findings were compared with histology. Results: Cell labeling efficiency was more than 95% by Perls Prussian blue stain. After transplantation of labeled BMSCs via portal vein, liver's had diffuse granular signal intensity appearance in T 2 * WI MRI. Cells were detected for up to 2 w in receipts' liver's. At histologic analysis, signal intensity loss correlated with iron-loaded cells. Conclusion: MR imaging could aid in monitoring of magnetically labeled BMSCs administered via portal vein in vivo. (authors)

  18. Inflated Grades, Enrollments & Budgets

    Directory of Open Access Journals (Sweden)

    J. E. Stone

    1995-06-01

    Full Text Available Reports of the past 13 years that call attention to deficient academic standards in American higher education are enumerated. Particular attention is given the Wingspread Group's recent An American Imperative: Higher Expectations for Higher Education. Low academic standards, grade inflation, and budgetary incentives for increased enrollment are analyzed and a call is made for research at the state level. Reported trends in achievement and GPAs are extrapolated to Tennessee and combined with local data to support the inference that 15% of the state's present day college graduates would not have earned a diploma by mid 1960s standards. A conspicuous lack of interest by public oversight bodies is noted despite a growing public awareness of low academic expectations and lenient grading and an implicit budgetary impact of over $100 million. Various academic policies and the dynamics of bureaucratic control are discussed in relationship to the maintenance of academic standards. The disincentives for challenging course requirements and responsible grading are examined, and the growing movement to address academic quality issues through better training and supervision of faculty are critiqued. Recommendations that would encourage renewed academic integrity and make learning outcomes visible to students, parents, employers, and the taxpaying public are offered and briefly discussed.

  19. A system for aerodynamically sizing ultrafine environmental radioactive particles

    International Nuclear Information System (INIS)

    Olawoyin, L.

    1995-09-01

    The unattached environmental radioactive particles/clusters, produced mainly by 222 Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It's major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented

  20. A system for aerodynamically sizing ultrafine environmental radioactive particles

    Energy Technology Data Exchange (ETDEWEB)

    Olawoyin, L.

    1995-09-01

    The unattached environmental radioactive particles/clusters, produced mainly by {sup 222}Rn in indoor air, are usually few nanometers in size. The inhalation of these radioactive clusters can lead to deposition of radioactivity on the mucosal surface of the tracheobronchial tree. The ultimate size of the cluster together with the flow characteristics will determine the depositional site in the human lung and thus, the extent of damage that can be caused. Thus, there exists the need for the determination of the size of the radioactive clusters. However, the existing particle measuring device have low resolution in the sub-nanometer range. In this research, a system for the alternative detection and measurement of the size of particles/cluster in the less than 2 nm range have been developed. The system is a one stage impactor which has a solid state spectrometer as its impaction plate. It`s major feature is the nozzle-to-plate separation, L. The particle size collected changes with L and thus, particle size spectroscopy is achieved by varying L. The number of collected particles is determined by alpha spectroscopy. The size-discriminating ability of the system was tested with laboratory generated radon particles and it was subsequently used to characterize the physical (size) changes associated with the interaction of radon progeny with water vapor and short chain alcohols in various support gases. The theory of both traditional and high velocity jet impactors together with the design and evaluation of the system developed in this study are discussed in various chapters of this dissertation. The major results obtained in the course of the study are also presented.

  1. Order in nanometer thick intergranular films at Au-sapphire interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baram, Mor [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Garofalini, Stephen H. [Department of Materials Science and Engineering, Rutgers University, Piscataway, NJ 08854-8065 (United States); Kaplan, Wayne D., E-mail: kaplan@tx.technion.ac.il [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2011-08-15

    Highlights: {yields} Au particles were equilibrated on (0 0 0 1) sapphire in the presence of anorthite. {yields} 1.2 nm thick equilibrium films (complexions) were formed at the Au-sapphire interfaces. {yields} Quantitative HRTEM was used to study the atomistic structure of the films. {yields} Structural order was observed in the 1.2 nm thick films adjacent to the sapphire crystal. {yields} This demonstrates that ordering is an intrinsic part of equilibrium intergranular films. - Abstract: In recent years extensive studies on interfaces have shown that {approx}1 nm thick intergranular films (IGF) exist at interfaces in different material systems, and that IGF can significantly affect the materials' properties. However, there is great deal of uncertainty whether such films are amorphous or partially ordered. In this study specimens were prepared from Au particles that were equilibrated on sapphire substrates in the presence of anorthite glass, leading to the formation of 1.2 nm thick IGF at the Au-sapphire interfaces. Site-specific cross-section samples were characterized using quantitative high resolution transmission electron microscopy to study the atomistic structure of the films. Order was observed in the 1.2 nm thick films adjacent to the sapphire crystal in the form of 'Ca cages', experimentally demonstrating that ordering is an intrinsic part of IGF, as predicted from molecular dynamics and diffuse interface theory.

  2. TCGA_LowerGradeGliomas

    Science.gov (United States)

    TCGA researchers analyzed nearly 300 cases of diffuse low- and intermediate-grade gliomas, which together comprise lower-grade gliomas. LGGs occur mainly in adults and include astrocytomas, oligodendrogliomas and oligoastrocytomas.

  3. Self-assembly via anisotropic interactions : Modeling association kinetics of patchy particle systems and self-assembly induced by critical Casimir forces

    NARCIS (Netherlands)

    Newton, A.C.

    2017-01-01

    Self-assembly, the non-dissipative spontaneous formation of structural order spans many length scales, from amphiphilic molecules forming micelles to stars forming galaxies. This thesis mainly deals with systems on the colloidal length scale where the size of a particle is between a nanometer and a

  4. Particle detectors

    CERN Document Server

    Hilke, Hans Jürgen; Joram, Christian; CERN. Geneva

    1991-01-01

    Lecture 5: Detector characteristics: ALEPH Experiment cut through the devices and events - Discuss the principles of the main techniques applied to particle detection ( including front-end electronics), the construction and performance of some of the devices presently in operartion and a few ideas on the future performance. Lecture 4-pt. b Following the Scintillators. Lecture 4-pt. a : Scintillators - Used for: -Timing (TOF, Trigger) - Energy Measurement (Calorimeters) - Tracking (Fibres) Basic scintillation processes- Inorganic Scintillators - Organic Scintil - Discuss the principles of the main techniques applied to particle detection ( including front-end electronics), the construction and performance of some of the devices presently in operation and a fiew ideas on future developpement session 3 - part. b Following Calorimeters lecture 3-pt. a Calorimeters - determine energy E by total absorption of charged or neutral particles - fraction of E is transformed into measurable quantities - try to acheive sig...

  5. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  6. Surface features on Sahara soil dust particles made visible by atomic force microscope (AFM) phase images

    OpenAIRE

    G. Helas; M. O. Andreae

    2008-01-01

    We show that atomic force microscopy (AFM) phase images can reveal surface features of soil dust particles, which are not evident using other microscopic methods. The non-contact AFM method is able to resolve topographical structures in the nanometer range as well as to uncover repulsive atomic forces and attractive van der Waals' forces, and thus gives insight to surface properties. Though the method does not allow quantitative assignment in terms of chemical compound description, it clearly...

  7. Let's End the Grading Game.

    Science.gov (United States)

    Edwards, Clifford H.; Edwards, Laurie

    1999-01-01

    Argues that grades have negative effects on learning and self-concept. States that while grading has a long tradition of sorting children for college entrance, there is limited evidence that grades serve a valid purpose. Argues that this practice should be abolished and an evaluation system established that provides a more valid estimate of…

  8. Four Steps in Grading Reform

    Science.gov (United States)

    Guskey, Thomas R.; Jung, Lee Ann

    2012-01-01

    The field of education is moving rapidly toward a standards-based approach to grading. School leaders have become increasingly aware of the tremendous variation that exists in grading practices, even among teachers of the same courses in the same department in the same school. Consequently, students' grades often have little relation to their…

  9. Particle physics

    CERN Document Server

    Martin, Brian R

    2017-01-01

    An accessible and carefully structured introduction to Particle Physics, including important coverage of the Higgs Boson and recent progress in neutrino physics. Fourth edition of this successful title in the Manchester Physics series. Includes information on recent key discoveries including : An account of the discovery of exotic hadrons, beyond the simple quark model; Expanded treatments of neutrino physics and CP violation in B-decays; An updated account of ‘physics beyond the standard model’, including the interaction of particle physics with cosmology; Additional problems in all chapters, with solutions to selected problems available on the book’s website; Advanced material appears in optional starred sections.

  10. Relationships among surface processing at the nanometer scale, nanostructure and optical properties of thin oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Losurdo, Maria

    2004-05-01

    Spectroscopic ellipsometry is used to study the optical properties of nanostructured semiconductor oxide thin films. Various examples of models for the dielectric function, based on Lorentzian oscillators combined with the Drude model, are given based on the band structure of the analyzed oxide. With this approach, the optical properties of thin films are determined independent of the dielectric functions of the corresponding bulk materials, and correlation between the optical properties and nanostructure of thin films is investigated. In particular, in order to discuss the dependence of optical constants on grain size, CeO{sub 2} nanostructured films are considered and parameterized by two-Lorentzian oscillators or two-Tauc-Lorentz model depending on the nanostructure and oxygen deficiency. The correlation among anisotropy, crystalline fraction and optical properties parameterized by a four-Lorentz oscillator model is discussed for nanocrystalline V{sub 2}O{sub 5} thin films. Indium tin oxide thin films are discussed as an example of the presence of graded optical properties related to interfacial reactivity activated by processing conditions. Finally, the example of ZnO shows the potential of ellipsometry in discerning crystal and epitaxial film polarity through the analysis of spectra and the detection of surface reactivity of the two polar faces, i.e. Zn-polarity and O-polarity.

  11. Single-particle colloid tracking in four dimensions.

    Science.gov (United States)

    Anthony, Stephen M; Hong, Liang; Kim, Minsu; Granick, Steve

    2006-11-21

    Coating a close-packed fluorescent colloid monolayer with a nanometer-thick metal film followed by sonication in liquid produces modulated optical nanoprobes. The metal coating modulates the fluorescence as these structures rotate in suspension, enabling the use of these particles as probes to monitor both rotational and center-of-mass (translational) dynamics in complex environments. Here, we demonstrate methods to simultaneously measure two translational and two rotational degrees of freedom, with excellent agreement to theory. The capability to determine two angles of rotation opens several new avenues of future research.

  12. Functionally graded materials produced with high power lasers

    NARCIS (Netherlands)

    De Hosson, J. T. M.; Ocelik, V.; Chandra, T; Torralba, JM; Sakai, T

    2003-01-01

    In this keynote paper two examples will be present of functionally graded materials produced with high power Nd:YAG lasers. In particular the conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of A18Si and Ti6Al4V alloys are presented. The formation of

  13. Low PIP2 molar fractions induce nanometer size clustering in giant unilamellar vesicles containing POPC

    DEFF Research Database (Denmark)

    Salvemini, Iyrri; Gaua, D.; Reid, J.

    2014-01-01

    generalized polarization function (GP) with unlabeled PIP2 and single point fluorescence correlation spectroscopy and brightness analysis of various BODIPY labeled PIP2 to determine the presence of clusters in the membrane of giant unilamellar vesicles (GUVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3......-phosphocholine (POPC) or a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), sphingomyelin and cholesterol. We determined the number of freely diffusing fluorescent BODIPY molecules in the membrane and found that in GUVs containing various amounts of labeled PIP2, this number was significantly lower...... than in GUVs made with the control BODIPY labeled hexadecyl phosphatidylcholine (BODIPY-HPC). Also, we noted an increase in brightness of the labeled PIP2 particles with increasing labeled PIP2 molar fraction. Together with the observed change in LAURDAN GP with increasing molar fraction of unlabeled...

  14. Airborne Nanostructured Particles and Occupational Health

    Science.gov (United States)

    Maynard, Andrew D.; Kuempel, Eileen D.

    2005-12-01

    Nanotechnology is leading to the development in many field, of new materials and devices in many fields that demonstrate nanostructure-dependent properties. However, concern has been expressed that these same properties may present unique challenges to addressing potential health impact. Airborne particles associated with engineered nanomaterials are of particular concern, as they can readily enter the body through inhalation. Research into the potential occupational health risks associated with inhaling engineered nanostructured particles is just beginning. However, there is a large body of data on occupational and environmental aerosols, which is applicable to developing an initial assessment of potential risk and risk reduction strategies. Epidemiological and pathological studies of occupational and environmental exposures to airborne particles and fibers provide information on the aerosol-related lung diseases and conditions that have been observed in humans. Toxicological studies provide information on the specific disease mechanisms, dose-response relationships, and the particle characteristics that influence toxicity, including the size, surface area, chemistry or reactivity, solubility, and shape. Potential health risk will depend on the magnitude and nature of exposures to airborne nanostructured particles, and on the release, dispersion, transformation and control of materials in the workplace. Aerosol control methods have not been well-characterized for nanometer diameter particles, although theory and limited experimental data indicate that conventional ventilation, engineering control and filtration approaches should be applicable in many situations. Current information supports the development of preliminary guiding principles on working with engineered nanomaterials. However critical research questions remain to be answered before the potential health risk of airborne nanostructured particles in the workplace can be fully addressed.

  15. Mechanism and Prediction of Gas Permeation through Sub-Nanometer Graphene Pores: Comparison of Theory and Simulation.

    Science.gov (United States)

    Yuan, Zhe; Govind Rajan, Ananth; Misra, Rahul Prasanna; Drahushuk, Lee W; Agrawal, Kumar Varoon; Strano, Michael S; Blankschtein, Daniel

    2017-08-22

    Due to its atomic thickness, porous graphene with sub-nanometer pore sizes constitutes a promising candidate for gas separation membranes that exhibit ultrahigh permeances. While graphene pores can greatly facilitate gas mixture separation, there is currently no validated analytical framework with which one can predict gas permeation through a given graphene pore. In this work, we simulate the permeation of adsorptive gases, such as CO 2 and CH 4 , through sub-nanometer graphene pores using molecular dynamics simulations. We show that gas permeation can typically be decoupled into two steps: (1) adsorption of gas molecules to the pore mouth and (2) translocation of gas molecules from the pore mouth on one side of the graphene membrane to the pore mouth on the other side. We find that the translocation rate coefficient can be expressed using an Arrhenius-type equation, where the energy barrier and the pre-exponential factor can be theoretically predicted using the transition state theory for classical barrier crossing events. We propose a relation between the pre-exponential factor and the entropy penalty of a gas molecule crossing the pore. Furthermore, on the basis of the theory, we propose an efficient algorithm to calculate CO 2 and CH 4 permeances per pore for sub-nanometer graphene pores of any shape. For the CO 2 /CH 4 mixture, the graphene nanopores exhibit a trade-off between the CO 2 permeance and the CO 2 /CH 4 separation factor. This upper bound on a Robeson plot of selectivity versus permeance for a given pore density is predicted and described by the theory. Pores with CO 2 /CH 4 separation factors higher than 10 2 have CO 2 permeances per pore lower than 10 -22 mol s -1 Pa -1 , and pores with separation factors of ∼10 have CO 2 permeances per pore between 10 -22 and 10 -21 mol s -1 Pa -1 . Finally, we show that a pore density of 10 14 m -2 is required for a porous graphene membrane to exceed the permeance-selectivity upper bound of polymeric

  16. Accounting for nanometer-thick adventitious carbon contamination in X-ray absorption spectra of carbon-based materials.

    Science.gov (United States)

    Mangolini, Filippo; McClimon, J Brandon; Rose, Franck; Carpick, Robert W

    2014-12-16

    Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy is a powerful technique for characterizing the composition and bonding state of nanoscale materials and the top few nanometers of bulk and thin film specimens. When coupled with imaging methods like photoemission electron microscopy, it enables chemical imaging of materials with nanometer-scale lateral spatial resolution. However, analysis of NEXAFS spectra is often performed under the assumption of structural and compositional homogeneity within the nanometer-scale depth probed by this technique. This assumption can introduce large errors when analyzing the vast majority of solid surfaces due to the presence of complex surface and near-surface structures such as oxides and contamination layers. An analytical methodology is presented for removing the contribution of these nanoscale overlayers from NEXAFS spectra of two-layered systems to provide a corrected photoabsorption spectrum of the substrate. This method relies on the subtraction of the NEXAFS spectrum of the overlayer adsorbed on a reference surface from the spectrum of the two-layer system under investigation, where the thickness of the overlayer is independently determined by X-ray photoelectron spectroscopy (XPS). This approach is applied to NEXAFS data acquired for one of the most challenging cases: air-exposed hard carbon-based materials with adventitious carbon contamination from ambient exposure. The contribution of the adventitious carbon was removed from the as-acquired spectra of ultrananocrystalline diamond (UNCD) and hydrogenated amorphous carbon (a-C:H) to determine the intrinsic photoabsorption NEXAFS spectra of these materials. The method alters the calculated fraction of sp(2)-hybridized carbon from 5 to 20% and reveals that the adventitious contamination can be described as a layer containing carbon and oxygen ([O]/[C] = 0.11 ± 0.02) with a thickness of 0.6 ± 0.2 nm and a fraction of sp(2)-bonded carbon of 0.19 ± 0.03. This

  17. Size-dependent nonlocal effects in plasmonic semiconductor particles

    DEFF Research Database (Denmark)

    Maack, Johan Rosenkrantz; Mortensen, N. Asger; Wubs, Martijn

    2017-01-01

    Localized surface plasmons (LSP) in semiconductor particles are expected to exhibit spatial nonlocal response effects as the geometry enters the nanometer scale. To investigate these nonlocal effects, we apply the hydrodynamic model to nanospheres of two different semiconductor materials: intrinsic...... InSb and n-doped GaAs. Our results show that the semiconductors indeed display nonlocal effects, and that these effects are even more pronounced than in metals. In a 150 nm InSb particle at 300 K, the LSP frequency is blueshifted 35%, which is orders of magnitude larger than the blueshift in a metal...... particle of the same size. This property, together with their tunability, makes semiconductors a promising platform for experiments in nonlocal effects. Copyright (C)EPLA, 2017...

  18. Elementary particles

    International Nuclear Information System (INIS)

    Prasad, R.

    1984-01-01

    Two previous monographs report on investigations into the extent to which a unified field theory can satisfactorily describe physical reality. The first, Unified field Theory, showed that the paths within a non-Riemannian space are governed by eigenvalue equations. The second, Fundamental Constants, show that the field tensors satisfy sets of differential equations with solutions which represent the evolution of the fields along the paths of the space. The results from the first two monographs are used in this one to make progress on the theory of elementary particles. The five chapters are as follows - Quantum mechanics, gravitation and electromagnetism are aspects of the Unified theory; the fields inside the particle; the quadratic and linear theories; the calculation of the eigenvalues and elementary particles as stable configurations of interacting fields. It is shown that it is possible to construct an internal structure theory for elementary particles. The theory lies within the framework of Einstein's programme-to identify physical reality with a specified geometrical structure. (U.K.)

  19. Pinpointing particles

    International Nuclear Information System (INIS)

    Miller, David J.

    1987-01-01

    The Conference on Position-Sensitive Detectors held at London's University College from 7-11 September highlighted the importance and the growing applications of these precision devices in many branches of science, underlining once again the high spinoff potential for techniques developed inside particle physics

  20. Particle tracking

    International Nuclear Information System (INIS)

    Mais, H.; Ripken, G.; Wrulich, A.; Schmidt, F.

    1986-02-01

    After a brief description of typical applications of particle tracking in storage rings and after a short discussion of some limitations and problems related with tracking we summarize some concepts and methods developed in the qualitative theory of dynamical systems. We show how these concepts can be applied to the proton ring HERA. (orig.)

  1. Pinpointing particles

    Energy Technology Data Exchange (ETDEWEB)

    Miller, David J.

    1987-10-15

    The Conference on Position-Sensitive Detectors held at London's University College from 7-11 September highlighted the importance and the growing applications of these precision devices in many branches of science, underlining once again the high spinoff potential for techniques developed inside particle physics.

  2. Particle Physics

    CERN Multimedia

    2005-01-01

    While biomedicine and geoscience use grids to bring together many different sub-disciplines, particle physicists use grid computing to increase computing power and storage resources, and to access and analyze vast amounts of data collected from detectors at the world's most powerful accelerators (1 page)

  3. Non-exponential resistive switching in Ag2S memristors: a key to nanometer-scale non-volatile memory devices.

    Science.gov (United States)

    Gubicza, Agnes; Csontos, Miklós; Halbritter, András; Mihály, György

    2015-03-14

    The dynamics of resistive switchings in nanometer-scale metallic junctions formed between an inert metallic tip and an Ag film covered by a thin Ag2S layer are investigated. Our thorough experimental analysis and numerical simulations revealed that the resistance change upon a switching bias voltage pulse exhibits a strongly non-exponential behaviour yielding markedly different response times at different bias levels. Our results demonstrate the merits of Ag2S nanojunctions as nanometer-scale non-volatile memory cells with stable switching ratios, high endurance as well as fast response to write/erase, and an outstanding stability against read operations at technologically optimal bias and current levels.

  4. Differential optical shadow sensor for sub-nanometer displacement measurement and its application to drag-free satellites.

    Science.gov (United States)

    Zoellner, Andreas; Tan, Si; Saraf, Shailendhar; Alfauwaz, Abdul; DeBra, Dan; Buchman, Sasha; Lipa, John A

    2017-10-16

    We present a method for 3D sub-nanometer displacement measurement using a set of differential optical shadow sensors. It is based on using pairs of collimated beams on opposite sides of an object that are partially blocked by it. Applied to a sphere, our 3-axis sensor module consists of 8 parallel beam-detector sets for redundancy. The sphere blocks half of each beam's power in the nominal centered position, and any displacement can be measured by the differential optical power changes amongst the pairs of detectors. We have experimentally demonstrated a displacement sensitivity of 0.87nm/Hz at 1 Hz and 0.39nm/Hz at 10 Hz. We describe the application of the module to the inertial sensor of a drag-free satellite, which can potentially be used for navigation, geodesy and fundamental science experiments as well as ground based applications.

  5. Characterization of nanometer-scale porosity in reservoir carbonate rock by focused ion beam-scanning electron microscopy.

    Science.gov (United States)

    Bera, Bijoyendra; Gunda, Naga Siva Kumar; Mitra, Sushanta K; Vick, Douglas

    2012-02-01

    Sedimentary carbonate rocks are one of the principal porous structures in natural reservoirs of hydrocarbons such as crude oil and natural gas. Efficient hydrocarbon recovery requires an understanding of the carbonate pore structure, but the nature of sedimentary carbonate rock formation and the toughness of the material make proper analysis difficult. In this study, a novel preparation method was used on a dolomitic carbonate sample, and selected regions were then serially sectioned and imaged by focused ion beam-scanning electron microscopy. The resulting series of images were used to construct detailed three-dimensional representations of the microscopic pore spaces and analyze them quantitatively. We show for the first time the presence of nanometer-scale pores (50-300 nm) inside the solid dolomite matrix. We also show the degree of connectivity of these pores with micron-scale pores (2-5 μm) that were observed to further link with bulk pores outside the matrix.

  6. Fabrication of nanometer flat areas onto YBa2Cu3O7-x thin film surfaces by scanning tunneling microscope

    International Nuclear Information System (INIS)

    Virtanen, J.A.; Suketu, P.; Huth, G.C.; Cho, Z.H.

    1991-01-01

    A scanning tunneling microscope was used to mechanically ''mill'' nanometer flat areas of up to 1600 μm 2 on high temperature superconducting (HTS) films of YBa 2 Cu 3 O 7-x which were originally formed by laser ablation. Flatness to a standard deviation of 2 nm in height was found to be characteristic of milled areas. It was subsequently possible to mill trenches and ditches onto these flat areas. Scanning tunneling measurements of the exposed layered structure of the milled HTS surface are also reported. Surface modifications are also possible by the application of voltage pulse to the tunneling tip. The combination of electrical pulses and milling offer a possibility of mixed electromechanical patterning of the film

  7. Large-scale freestanding nanometer-thick graphite pellicles for mass production of nanodevices beyond 10 nm.

    Science.gov (United States)

    Kim, Seul-Gi; Shin, Dong-Wook; Kim, Taesung; Kim, Sooyoung; Lee, Jung Hun; Lee, Chang Gu; Yang, Cheol-Woong; Lee, Sungjoo; Cho, Sang Jin; Jeon, Hwan Chul; Kim, Mun Ja; Kim, Byung-Gook; Yoo, Ji-Beom

    2015-09-21

    Extreme ultraviolet lithography (EUVL) has received much attention in the semiconductor industry as a promising candidate to extend dimensional scaling beyond 10 nm. We present a new pellicle material, nanometer-thick graphite film (NGF), which shows an extreme ultraviolet (EUV) transmission of 92% at a thickness of 18 nm. The maximum temperature induced by laser irradiation (λ = 800 nm) of 9.9 W cm(-2) was 267 °C, due to the high thermal conductivity of the NGF. The freestanding NGF was found to be chemically stable during annealing at 500 °C in a hydrogen environment. A 50 × 50 mm large area freestanding NGF was fabricated using the wet and dry transfer (WaDT) method. The NGF can be used as an EUVL pellicle for the mass production of nanodevices beyond 10 nm.

  8. Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

    Institute of Scientific and Technical Information of China (English)

    史建明; 包永忠; 黄志明; 翁志学

    2004-01-01

    Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

  9. Mechanical design of multiple zone plates precision alignment apparatus for hard X-ray focusing in twenty-nanometer scale

    Energy Technology Data Exchange (ETDEWEB)

    Shu, Deming; Liu, Jie; Gleber, Sophie C.; Vila-Comamala, Joan; Lai, Barry; Maser, Jorg M.; Roehrig, Christian; Wojcik, Michael J.; Vogt, Franz Stefan

    2017-04-04

    An enhanced mechanical design of multiple zone plates precision alignment apparatus for hard x-ray focusing in a twenty-nanometer scale is provided. The precision alignment apparatus includes a zone plate alignment base frame; a plurality of zone plates; and a plurality of zone plate holders, each said zone plate holder for mounting and aligning a respective zone plate for hard x-ray focusing. At least one respective positioning stage drives and positions each respective zone plate holder. Each respective positioning stage is mounted on the zone plate alignment base frame. A respective linkage component connects each respective positioning stage and the respective zone plate holder. The zone plate alignment base frame, each zone plate holder and each linkage component is formed of a selected material for providing thermal expansion stability and positioning stability for the precision alignment apparatus.

  10. Crossed Ga2O3/SnO2 multiwire architecture: a local structure study with nanometer resolution.

    Science.gov (United States)

    Martínez-Criado, Gema; Segura-Ruiz, Jaime; Chu, Manh-Hung; Tucoulou, Remi; López, Iñaki; Nogales, Emilio; Mendez, Bianchi; Piqueras, Javier

    2014-10-08

    Crossed nanowire structures are the basis for high-density integration of a variety of nanodevices. Owing to the critical role of nanowires intersections in creating hybrid architectures, it has become a challenge to investigate the local structure in crossing points in metal oxide nanowires. Thus, if intentionally grown crossed nanowires are well-patterned, an ideal model to study the junction is formed. By combining electron and synchrotron beam nanoprobes, we show here experimental evidence of the role of impurities in the coupling formation, structural modifications, and atomic site configuration based on crossed Ga2O3/SnO2 nanowires. Our experiment opens new avenues for further local structure studies with both nanometer resolution and elemental sensitivity.

  11. Compressive flow behavior of Cu thin films and Cu/Nb multilayers containing nanometer-scale helium bubbles

    International Nuclear Information System (INIS)

    Li, N.; Mara, N.A.; Wang, Y.Q.; Nastasi, M.; Misra, A.

    2011-01-01

    Research highlights: → Firstly micro-pillar compression technique has been used to measure the implanted metal films. → The magnitude of radiation hardening decreased with decreasing layer thickness. → When thickness decreases to 2.5 nm, no hardening and no loss in deformability after implantation. -- Focused-ion-beam machined compression specimens were used to investigate the effect of nanometer-scale helium bubbles on the strength and deformability of sputter-deposited Cu and Cu/Nb multilayers with different layer thickness. The flow strength of Cu films increased by more than a factor of 2 due to helium bubbles but in multilayers, the magnitude of radiation hardening decreased with decreasing layer thickness. When the layer thickness decreases to 2.5 nm, insignificant hardening and no measurable loss in deformability is observed after implantation.

  12. Elastic recoil atomic spectroscopy of light elements with sub-nanometer depth resolution

    International Nuclear Information System (INIS)

    Kosmata, Marcel

    2011-01-01

    In this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two components. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a highresistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during

  13. Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

    Science.gov (United States)

    Gerstl, Stephan S. A.

    Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

  14. Magnified Image Spatial Spectrum (MISS) microscopy for nanometer and millisecond scale label-free imaging

    Science.gov (United States)

    Majeed, Hassaan; Ma, Lihong; Lee, Young Jae; Kandel, Mikhail; Min, Eunjung; Jung, Woonggyu; Best-Popescu, Catherine; Popescu, Gabriel

    2018-03-01

    Label-free imaging of rapidly moving, sub-diffraction sized structures has important applications in both biology and material science, as it removes the limitations associated with fluorescence tagging. However, unlabeled nanoscale particles in suspension are difficult to image due to their transparency and fast Brownian motion. Here we describe a novel interferometric imaging technique referred to as Magnified Image Spatial Spectrum (MISS) microscopy, which overcomes these challenges. The MISS microscope provides quantitative phase information and enables dynamic light scattering investigations with an overall optical path length sensitivity of 0.95 nm at 833 frames per second acquisition rate. Using spatiotemporal filtering, we find that the sensitivity can be further pushed down to 0.001-0.01 nm. We demonstrate the instrument's capability through colloidal nanoparticle sizing down to 20 nm diameter and measurements of live neuron membrane dynamics. MISS microscopy is implemented as an upgrade module to an existing microscope, which converts it into a powerful light scattering instrument. Thus, we anticipate that MISS will be adopted broadly for both material and life sciences applications.

  15. Active particles

    CERN Document Server

    Degond, Pierre; Tadmor, Eitan

    2017-01-01

    This volume collects ten surveys on the modeling, simulation, and applications of active particles using methods ranging from mathematical kinetic theory to nonequilibrium statistical mechanics. The contributing authors are leading experts working in this challenging field, and each of their chapters provides a review of the most recent results in their areas and looks ahead to future research directions. The approaches to studying active matter are presented here from many different perspectives, such as individual-based models, evolutionary games, Brownian motion, and continuum theories, as well as various combinations of these. Applications covered include biological network formation and network theory; opinion formation and social systems; control theory of sparse systems; theory and applications of mean field games; population learning; dynamics of flocking systems; vehicular traffic flow; and stochastic particles and mean field approximation. Mathematicians and other members of the scientific commu...

  16. Hot particles

    International Nuclear Information System (INIS)

    Merwin, S.E.; Moeller, M.P.

    1989-01-01

    Nuclear Regulatory Commission (NRC) licensees are required to assess the dose to skin from a hot particle contamination event at a depth of skin of7mg/cm 2 over an area of 1 cm 2 and compare the value to the current dose limit for the skin. Although the resulting number is interesting from a comparative standpoint and can be used to predict local skin reactions, comparison of the number to existing limits based on uniform exposures is inappropriate. Most incidents that can be classified as overexposures based on this interpretation of dose actually have no effect on the health of the worker. As a result, resources are expended to reduce the likelihood that an overexposure event will occur when they could be directed toward eliminating the cause of the problem or enhancing existing programs such as contamination control. Furthermore, from a risk standpoint, this practice is not ALARA because some workers receive whole body doses in order to minimize the occurrence of hot particle skin contaminations. In this paper the authors suggest an alternative approach to controlling hot particle exposures

  17. Track structure of protons and other light ions in liquid water: applications of the LIonTrack code at the nanometer scale.

    Science.gov (United States)

    Bäckström, G; Galassi, M E; Tilly, N; Ahnesjö, A; Fernández-Varea, J M

    2013-06-01

    The LIonTrack (Light Ion Track) Monte Carlo (MC) code for the simulation of H(+), He(2+), and other light ions in liquid water is presented together with the results of a novel investigation of energy-deposition site properties from single ion tracks. The continuum distorted-wave formalism with the eikonal initial state approximation (CDW-EIS) is employed to generate the initial energy and angle of the electrons emitted in ionizing collisions of the ions with H2O molecules. The model of Dingfelder et al. ["Electron inelastic-scattering cross sections in liquid water," Radiat. Phys. Chem. 53, 1-18 (1998); "Comparisons of calculations with PARTRAC and NOREC: Transport of electrons in liquid water," Radiat. Res. 169, 584-594 (2008)] is linked to the general-purpose MC code PENELOPE/penEasy to simulate the inelastic interactions of the secondary electrons in liquid water. In this way, the extended PENELOPE/penEasy code may provide an improved description of the 3D distribution of energy deposits (EDs), making it suitable for applications at the micrometer and nanometer scales. Single-ionization cross sections calculated with the ab initio CDW-EIS formalism are compared to available experimental values, some of them reported very recently, and the theoretical electronic stopping powers are benchmarked against those recommended by the ICRU. The authors also analyze distinct aspects of the spatial patterns of EDs, such as the frequency of nearest-neighbor distances for various radiation qualities, and the variation of the mean specific energy imparted in nanoscopic targets located around the track. For 1 MeV/u particles, the C(6+) ions generate about 15 times more clusters of six EDs within an ED distance of 3 nm than H(+). On average clusters of two to three EDs for 1 MeV/u H(+) and clusters of four to five EDs for 1 MeV/u C(6+) could be expected for a modeling double strand break distance of 3.4 nm.

  18. Functionally Graded Materials Database

    Science.gov (United States)

    Kisara, Katsuto; Konno, Tomomi; Niino, Masayuki

    2008-02-01

    Functionally Graded Materials Database (hereinafter referred to as FGMs Database) was open to the society via Internet in October 2002, and since then it has been managed by the Japan Aerospace Exploration Agency (JAXA). As of October 2006, the database includes 1,703 research information entries with 2,429 researchers data, 509 institution data and so on. Reading materials such as "Applicability of FGMs Technology to Space Plane" and "FGMs Application to Space Solar Power System (SSPS)" were prepared in FY 2004 and 2005, respectively. The English version of "FGMs Application to Space Solar Power System (SSPS)" is now under preparation. This present paper explains the FGMs Database, describing the research information data, the sitemap and how to use it. From the access analysis, user access results and users' interests are discussed.

  19. Morphology and ultrastructure of retrovirus particles

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2015-08-01

    Full Text Available Retrovirus morphogenesis entails assembly of Gag proteins and the viral genome on the host plasma membrane, acquisition of the viral membrane and envelope proteins through budding, and formation of the core through the maturation process. Although in both immature and mature retroviruses, Gag and capsid proteins are organized as paracrystalline structures, the curvatures of these protein arrays are evidently not uniform within one or among all virus particles. The heterogeneity of retroviruses poses significant challenges to studying the protein contacts within the Gag and capsid lattices. This review focuses on current understanding of the molecular organization of retroviruses derived from the sub-nanometer structures of immature virus particles, helical capsid protein assemblies and soluble envelope protein complexes. These studies provide insight into the molecular elements that maintain the stability, flexibility and infectivity of virus particles. Also reviewed are morphological studies of retrovirus budding, maturation, infection and cell-cell transmission, which inform the structural transformation of the viruses and the cells during infection and viral transmission, and lead to better understanding of the interplay between the functioning viral proteins and the host cell.

  20. Industrial Implementation of Environmentally Friendly Nanometal Electroplating Process for Chromium and Copper Beryllium Replacement using Low Cost Pulse Current Power Supplies

    Science.gov (United States)

    2014-09-10

    FINAL REPORT Industrial Implementation of Environmentally Friendly Nanometal Electroplating Process for Chromium and Copper Beryllium...35 3.2 Phase II – Development/Verification that Nanotechnology Based Electroplating Process to Replace EHC/Cu-Be Processes are Compatible With...36 3.3 Phase III – Development of 200kW Power Supply and Compatible Nanostructured Electroplating Processed for Commercialization

  1. Synthesis and characterization of nanometer sized thermoelectric lead-antimony-silver-tellurium compounds and related materials

    International Nuclear Information System (INIS)

    Petri, Denis

    2012-01-01

    precipitates and crystal defects the thermal conductivity was generally low. Similar to other reports the powder processing caused a deleterious effect on the electrical conductivity. The comparison between short term annealed and long term sintered polycrystalline bulk samples revealed that the annealing temperature caused partly connected particles for the LAST-derivates but well sintered compacts for the non-LAST-compounds. For both classes, long-term sintering caused a simultanious increase of both thermopower and electrical conductivity which shows that co-ball milling leads to a decoupling of those two properties. This could prove usefull in further investigations and the development of new thermoelectric materials and the processing thereof.

  2. The Implications of Grade Inflation

    DEFF Research Database (Denmark)

    Smith, David E.; Fleisher, Steven

    2011-01-01

    The authors review current and past practices of the grade inflation controversy and present ways to return to each institution’s established grading guidelines. Students are graded based on knowledge gathered. Certain faculty members use thorough evaluative methods, such as written and oral pres...... have been profiled in the news. The model is provided to ensure that degree candidates are academic experts in their field, having earned the credential through rigorous study....

  3. Deep Metastable Eutectic Nanometer-Scale Particles in the MgO-Al2O3-SiO2 System

    Science.gov (United States)

    Reitmeijer, Frans J. M.; Nash, J. A., III

    2011-01-01

    Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains will anneal and adjust to local equilibrium but some will persist metastably depending on the time-temperature regime and melt/glass transformation.

  4. Hybrid electrokinetics for separation, mixing, and concentration of colloidal particles

    International Nuclear Information System (INIS)

    Sin, Mandy L Y; Shimabukuro, Yusuke; Wong, Pak Kin

    2009-01-01

    The advent of nanotechnology has facilitated the preparation of colloidal particles with adjustable sizes and the control of their size-dependent properties. Physical manipulation, such as separation, mixing, and concentration, of these colloidal particles represents an essential step for fully utilizing their potential in a wide spectrum of nanotechnology applications. In this study, we investigate hybrid electrokinetics, the combination of dielectrophoresis and electrohydrodynamics, for active manipulation of colloidal particles ranging from nanometers to micrometers in size. A concentric electrode configuration, which is optimized for generating electrohydrodynamic flow, has been designed to elucidate the effectiveness of hybrid electrokinetics and define the operating regimes for different microfluidic operations. The results indicate that the relative importance of electrohydrodynamics increases with decreasing particle size as predicted by a scaling analysis and that electrohydrodynamics is pivotal for manipulating nanoscale particles. Using the concentric electrodes, we demonstrate separation, mixing, and concentration of colloidal particles by adjusting the relative strengths of different electrokinetic phenomena. The effectiveness of hybrid electrokinetics indicates its potential to serve as a generic technique for active manipulation of colloidal particles in various nanotechnology applications.

  5. Aloe vera Induced Biomimetic Assemblage of Nucleobase into Nanosized Particles

    Science.gov (United States)

    Chauhan, Arun; Zubair, Swaleha; Sherwani, Asif; Owais, Mohammad

    2012-01-01

    Aim Biomimetic nano-assembly formation offers a convenient and bio friendly approach to fabricate complex structures from simple components with sub-nanometer precision. Recently, biomimetic (employing microorganism/plants) synthesis of metal and inorganic materials nano-particles has emerged as a simple and viable strategy. In the present study, we have extended biological synthesis of nano-particles to organic molecules, namely the anticancer agent 5-fluorouracil (5-FU), using Aloe vera leaf extract. Methodology The 5-FU nano- particles synthesized by using Aloe vera leaf extract were characterized by UV, FT-IR and fluorescence spectroscopic techniques. The size and shape of the synthesized nanoparticles were determined by TEM, while crystalline nature of 5-FU particles was established by X-ray diffraction study. The cytotoxic effects of 5-FU nanoparticles were assessed against HT-29 and Caco-2 (human adenocarcinoma colorectal) cell lines. Results Transmission electron microscopy and atomic force microscopic techniques confirmed nano-size of the synthesized particles. Importantly, the nano-assembled 5-FU retained its anticancer action against various cancerous cell lines. Conclusion In the present study, we have explored the potential of biomimetic synthesis of nanoparticles employing organic molecules with the hope that such developments will be helpful to introduce novel nano-particle formulations that will not only be more effective but would also be devoid of nano-particle associated putative toxicity constraints. PMID:22403622

  6. New particles

    Energy Technology Data Exchange (ETDEWEB)

    Khare, A.

    1980-07-01

    Current state of art in the discovery of new elementary particles is reviewed. At present, quarks and mesons are accepted as the basic constituents of matter. The charmonium model (canti-c system), and the 'open charm' are discussed. Explanations are offered for the recent discovery of the heavy lepton tau. Quark states such as the beauty and taste are also dealt with at length. The properties of the tanti-t bound system are speculated. It is concluded that the understanding of canti-c and banti-b families is facilitated by the assumption of the quarkonium model. Implications at the astrophysical level are indicated.

  7. Particle Mechanics

    CERN Document Server

    Collinson, Chris

    1995-01-01

    * Assumes no prior knowledge* Adopts a modelling approach* Numerous tutorial problems, worked examples and exercises included* Elementary topics augmented by planetary motion and rotating framesThis text provides an invaluable introduction to mechanicsm confining attention to the motion of a particle. It begins with a full discussion of the foundations of the subject within the context of mathematical modelling before covering more advanced topics including the theory of planetary orbits and the use of rotating frames of reference. Truly introductory , the style adoped is perfect for those u

  8. Fabrication of non-aging superhydrophobic surfaces by packing flower-like hematite particles

    Science.gov (United States)

    Cao, Anmin; Cao, Liangliang; Gao, Di

    2008-03-01

    We demonstrate the fabrication of non-aging superhydrophobic surfaces by packing flower-like micrometer-sized hematite particles. Although hematite is intrinsically hydrophilic, the nanometer-sized protrusions on the particles form textures with overhanging structures that prevent water from entering into the textures and induce a macroscopic superhydrophobic phenomenon. These superhydrophobic surfaces do not age even in extremely oxidative environments---they retain the superhydrophobicity after being stored in ambient laboratory air for 4 months, heated to 800 degree C in air for 10 hours, and exposed to ultraviolet ozone for 10 hours.

  9. Synthesis of nanometer metallic powders or its oxides by γ-ray reduction of salts aqueous solution

    International Nuclear Information System (INIS)

    Zhang Manwei; Zhu Yingjie; Qian Yitai; Chen Zuyao

    1995-01-01

    The nanocrystal powders of pure Ag, Cu, Ni, Pt, Au, Pd, Cd, Sn, Pb and Co were obtained by γ-radiation reduction of their salt aqueons solution. The average particle sizes of them are 5-45 nm respectively. the factors affecting the particle size and the formation and growth of the nanocrystal particles into single crystal are illustrated and discussed. the pure nanocrystal Cu 2 O powders were also successfully prepared. The mechanism of its formation is discussed. (author)

  10. Effect of limestone particle size on bone quality characteristics of ...

    African Journals Online (AJOL)

    A study was conducted to determine the effect of different limestone particle sizes in layer diets on bone quality characteristics at end-of-lay hens. Calcitic limestone (360 g Ca/kg DM) that is extensively used in commercial poultry diets was obtained from a specific South African source. Limestone particles were graded as ...

  11. Practicing Good Habits, Grade 4.

    Science.gov (United States)

    Van Cong Lau; And Others

    This illustrated textbook was designed for teaching civics and values to fourth grade students in Vietnam. It is divided into six chapters: (1) At School (recapitulation of the grade three program, friendship, respect for the teacher, team work, discipline, honor); (2) In the Street: Traffic Regulations; (3) At Home (the extended family spirit,…

  12. Graded geometry and Poisson reduction

    OpenAIRE

    Cattaneo, A S; Zambon, M

    2009-01-01

    The main result of [2] extends the Marsden-Ratiu reduction theorem [4] in Poisson geometry, and is proven by means of graded geometry. In this note we provide the background material about graded geometry necessary for the proof in [2]. Further, we provide an alternative algebraic proof for the main result. ©2009 American Institute of Physics

  13. Compositionally Graded Multilayer Ceramic Capacitors.

    Science.gov (United States)

    Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

    2017-09-27

    Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (filters and power converters.

  14. Fermilab | Particle Physics Division

    Science.gov (United States)

    Diversity Education Safety Sustainability and Environment Contact Science Science Particle Physics Neutrinos Scientific Computing Research & Development Key Discoveries Benefits of Particle Physics Particle Superconducting Test Accelerator LHC and Future Accelerators Accelerators for Science and Society Particle Physics

  15. Chemistry with spatial control using particles and streams†

    Science.gov (United States)

    Kalinin, Yevgeniy V.; Murali, Adithya

    2012-01-01

    Spatial control of chemical reactions, with micro- and nanometer scale resolution, has important consequences for one pot synthesis, engineering complex reactions, developmental biology, cellular biochemistry and emergent behavior. We review synthetic methods to engineer this spatial control using chemical diffusion from spherical particles, shells and polyhedra. We discuss systems that enable both isotropic and anisotropic chemical release from isolated and arrayed particles to create inhomogeneous and spatially patterned chemical fields. In addition to such finite chemical sources, we also discuss spatial control enabled with laminar flow in 2D and 3D microfluidic networks. Throughout the paper, we highlight applications of spatially controlled chemistry in chemical kinetics, reaction-diffusion systems, chemotaxis and morphogenesis. PMID:23145348

  16. Optomechanical Design of a Hard X-ray Nanoprobe Instrument with Nanometer-Scale Active Vibration Control

    International Nuclear Information System (INIS)

    Shu, D.; Preissner, C.; Smolyanitskiy, A.; Maser, J.; Winarski, R.; Holt, M.; Lai, B.; Vogt, S.; Stephenson, G. B.

    2007-01-01

    We are developing a new hard x-ray nanoprobe instrument that is one of the centerpieces of the characterization facilities of the Center for Nanoscale Materials being constructed at Argonne National Laboratory. This new probe will cover an energy range of 3-30 keV with 30-nm spacial resolution. The system is designed to accommodate x-ray optics with a resolution limit of 10 nm, therefore, it requires staging of x-ray optics and specimens with a mechanical repeatability of better than 5 nm. Fast feedback for differential vibration control between the zone-plate x-ray optics and the sample holder has been implemented in the design using a digital-signal-processor-based real-time closed-loop feedback technique. A specially designed, custom-built laser Doppler displacement meter system provides two-dimensional differential displacement measurements with subnanometer resolution between the zone-plate x-ray optics and the sample holder. The optomechanical design of the instrument positioning stage system with nanometer-scale active vibration control is presented in this paper

  17. Optomechanical design of a hard x-ray nanoprobe instrument with active vibration control in nanometer scale

    International Nuclear Information System (INIS)

    Shu, D.; Maser, J.; Holt, M.; Winarski, R.; Preissner, C.; Smolyanitskiy, A.; Lai, B.; Vogt, S.; Stephenson, G.

    2007-01-01

    We are developing a new hard x-ray nanoprobe instrument that is one of the centerpieces of the characterization facilities of the Center for Nanoscale Materials being constructed at Argonne National Laboratory. This new probe will cover an energy range of 3-30 keV with 30-nm spatial resolution. The system is designed to accommodate x-ray optics with a resolution limit of 10 nm, therefore, it requires staging of x-ray optics and specimens with a mechanical repeatability of better than 5 nm. Fast feedback for differential vibration control between the zone-plate x-ray optics and the sample holder has been implemented in the design using a digital-signal-processor-based real-time closed-loop feedback technique. A specially designed, custom-built laser Doppler displacement meter system provides two-dimensional differential displacement measurements with subnanometer resolution between the zone-plate x-ray optics and the sample holder. The optomechanical design of the instrument positioning stage system with nanometer-scale active vibration control is presented in this paper.

  18. Simple and rapid spectrophotometric determination of trace titanium (IV) enriched by nanometer size zirconium dioxide in natural water

    International Nuclear Information System (INIS)

    Zheng Fengying; Li Shunxing; Lin Luxiu; Cheng Liqing

    2009-01-01

    A novel method for preconcentration of Ti(IV) with nanometer size ZrO 2 and determination by spectrophotometry has been developed. Ti(IV) was selectively adsorbed on 300 mg ZrO 2 from 500 mL solution at pH 6.0, then eluted by 5 mL 11.3 mol L -1 HF. The eluent added was diantipyrylmethane (DAPM, as chromogenic reagent) and ascorbic acid (as masking agent), used for the analysis of Ti(IV) by measuring the absorbance at 390 nm with spectrophotometry, based on the chromogenic reaction between the Ti(IV) and DAPM. This method gave a concentration enhancement of 100 for 500 mL sample, eliminated the sizable interferences on direct determination with spectrophotometry. Detection limit (3σ, n = 11) of 0.1 μg L -1 was obtained. The method was applied to determine the concentration of Ti(IV) in river water and seawater and the analytical recoveries of Ti(IV) added to samples were 97.6-101.3%.

  19. Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks.

    Science.gov (United States)

    Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

    2018-06-22

    In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s -1 to 20 V s -1 , and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s -1 , suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

  20. Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks

    Science.gov (United States)

    Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

    2018-06-01

    In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s‑1 to 20 V s‑1, and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s‑1, suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

  1. Maskless X-Ray Writing of Electrical Devices on a Superconducting Oxide with Nanometer Resolution and Online Process Monitoring.

    Science.gov (United States)

    Mino, Lorenzo; Bonino, Valentina; Agostino, Angelo; Prestipino, Carmelo; Borfecchia, Elisa; Lamberti, Carlo; Operti, Lorenza; Fretto, Matteo; De Leo, Natascia; Truccato, Marco

    2017-08-22

    X-ray nanofabrication has so far been usually limited to mask methods involving photoresist impression and subsequent etching. Herein we show that an innovative maskless X-ray nanopatterning approach allows writing electrical devices with nanometer feature size. In particular we fabricated a Josephson device on a Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) superconducting oxide micro-crystal by drawing two single lines of only 50 nm in width using a 17.4 keV synchrotron nano-beam. A precise control of the fabrication process was achieved by monitoring in situ the variations of the device electrical resistance during X-ray irradiation, thus finely tuning the irradiation time to drive the material into a non-superconducting state only in the irradiated regions, without significantly perturbing the crystal structure. Time-dependent finite element model simulations show that a possible microscopic origin of this effect can be related to the instantaneous temperature increase induced by the intense synchrotron picosecond X-ray pulses. These results prove that a conceptually new patterning method for oxide electrical devices, based on the local change of electrical properties, is actually possible with potential advantages in terms of heat dissipation, chemical contamination, miniaturization and high aspect ratio of the devices.

  2. In situ deposition of poly(1,8-diaminonaphthalene): from thin films to nanometer-sized structures

    International Nuclear Information System (INIS)

    Tagowska, Magdalena; PaIys, Barbara; Mazur, Maciej; Skompska, Magdalena; Jackowska, Krystyna

    2005-01-01

    Chemical in situ deposition of poly(1,8-diaminonaphthalene) (p(1,8-DAN)) on conductive supports in aqueous and acetonitrile solutions was investigated using electrochemical quartz crystal microbalance (EQCM) and UV-vis spectroscopy. The resulting deposits were examined by the means of cyclic voltammetry (CV), FT-IR and Raman spectroscopy. P(1,8-DAN) was also deposited via chemical polymerization onto a porous polycarbonate membrane (PC) which served as a template for synthesis of nanometer-sized structures. The deposits of p(1,8-DAN) on PC substrate were imaged by atomic force microscopy (AFM) and the nanostructures obtained by dissolution of the template were visualized by scanning electron microscopy (SEM). The EQCM and UV-vis studies indicated that the polymer is formed both on the surface of the substrate and in the bulk of the polymerization solution. However, polymerization of 1,8-DAN in solution is delayed in comparison with deposition on the substrate. Electrochemical and spectroscopic properties of p(1,8-DAN) formed chemically closely resemble the properties of the electrosynthesized polymer. Furthermore, SEM images of p(1,8-DAN) nanostructures revealed that the polymer nanowires are formed in aqueous solutions, whereas two types of structures: nanowires and round shaped structures, not fitting to the pore size, can be obtained by chemical polymerization in the acetonitrile medium

  3. Interdiffusion in nanometer-scale multilayers investigated by in situ low-angle x-ray diffraction

    Science.gov (United States)

    Wang, Wei-Hua; Bai, Hai Yang; Zhang, Ming; Zhao, J. H.; Zhang, X. Y.; Wang, W. K.

    1999-04-01

    An in situ low-angle x-ray diffraction technique is used to investigate interdiffusion phenomena in various metal-metal and metal-amorphous Si nanometer-scale compositionally modulated multilayers (ML's). The temperature-dependent interdiffusivities are obtained by accurately monitoring the decay of the first-order modulation peak as a function of annealing time. Activation enthalpies and preexponential factors for the interdiffusion in the Fe-Ti, Ag-Bi, Fe-Mo, Mo-Si, Ni-Si, Nb-Si, and Ag-Si ML's are determined. Activation enthalpies and preexponential factors for the interdiffusion in the ML's are very small compared with that in amorphous alloys and crystalline solids. The relation between the atomic-size difference and interdiffusion in the ML's are investigated. The observed interdiffusion characteristics are compared with that in amorphous alloys and crystalline α-Zr, α-Ti, and Si. The experimental results suggest that a collective atomic-jumping mechanism govern the interdiffusion in the ML's, the collective proposal involving 8-15 atoms moving between extended nonequilibrium defects by thermal activation. The role of the interdiffusion in the solid-state reaction in the ML's is also discussed.

  4. Qualitative and quantitative analysis of an additive element in metal oxide nanometer film using laser induced breakdown spectroscopy.

    Science.gov (United States)

    Xiu, Junshan; Liu, Shiming; Sun, Meiling; Dong, Lili

    2018-01-20

    The photoelectric performance of metal ion-doped TiO 2 film will be improved with the changing of the compositions and concentrations of additive elements. In this work, the TiO 2 films doped with different Sn concentrations were obtained with the hydrothermal method. Qualitative and quantitative analysis of the Sn element in TiO 2 film was achieved with laser induced breakdown spectroscopy (LIBS) with the calibration curves plotted accordingly. The photoelectric characteristics of TiO 2 films doped with different Sn content were observed with UV visible absorption spectra and J-V curves. All results showed that Sn doping could improve the optical absorption to be red-shifted and advance the photoelectric properties of the TiO 2 films. We had obtained that when the concentration of Sn doping in TiO 2 films was 11.89  mmol/L, which was calculated by the LIBS calibration curves, the current density of the film was the largest, which indicated the best photoelectric performance. It indicated that LIBS was a potential and feasible measured method, which was applied to qualitative and quantitative analysis of the additive element in metal oxide nanometer film.

  5. Quantitative x-ray photoelectron spectroscopy: Simple algorithm to determine the amount of atoms in the outermost few nanometers

    International Nuclear Information System (INIS)

    Tougaard, Sven

    2003-01-01

    It is well known that due to inelastic electron scattering, the measured x-ray photoelectron spectroscopy peak intensity depends strongly on the in-depth atom distribution. Quantification based only on the peak intensity can therefore give large errors. The problem was basically solved by developing algorithms for the detailed analysis of the energy distribution of emitted electrons. These algorithms have been extensively tested experimentally and found to be able to determine the depth distribution of atoms with nanometer resolution. Practical application of these algorithms has increased after ready-to-use software packages were made available and they are now being used in laboratories worldwide. These software packages are easy to use but they need operator interaction. They are not well suited for automatic data processing and there is an additional need for simplified quantification strategies that can be automated. In this article we report on a very simple algorithm. It is a slightly more accurate version of our previous algorithm. The algorithm gives the amount of atoms within the outermost three inelastic mean free paths and it also gives a rough estimate for the in-depth distribution. An experimental example of its application is also presented

  6. Particle-based simulation of charge transport in discrete-charge nano-scale systems: the electrostatic problem

    OpenAIRE

    Berti, Claudio; Gillespie, Dirk; Eisenberg, Robert S; Fiegna, Claudio

    2012-01-01

    The fast and accurate computation of the electric forces that drive the motion of charged particles at the nanometer scale represents a computational challenge. For this kind of system, where the discrete nature of the charges cannot be neglected, boundary element methods (BEM) represent a better approach than finite differences/finite elements methods. In this article, we compare two different BEM approaches to a canonical electrostatic problem in a three-dimensional space with inhomogeneous...

  7. The Role of MAC1 in Diesel Exhaust Particle-induced Microglial Activation and Loss of Dopaminergic Neuron Function

    OpenAIRE

    Levesque, Shannon; Taetzsch, Thomas; Lull, Melinda E.; Johnson, Jo Anne; McGraw, Constance; Block, Michelle L.

    2013-01-01

    Increasing reports support that air pollution causes neuroinflammation and is linked to central nervous system (CNS) disease/damage. Diesel exhaust particles (DEP) are a major component of urban air pollution, which has been linked to microglial activation and Parkinson’s disease-like pathology. To begin to address how DEP may exert CNS effects, microglia and neuron-glia cultures were treated with either nanometer-sized DEP (

  8. Contact angle distribution of particles at fluid interfaces.

    Science.gov (United States)

    Snoeyink, Craig; Barman, Sourav; Christopher, Gordon F

    2015-01-27

    Recent measurements have implied a distribution of interfacially adsorbed particles' contact angles; however, it has been impossible to measure statistically significant numbers for these contact angles noninvasively in situ. Using a new microscopy method that allows nanometer-scale resolution of particle's 3D positions on an interface, we have measured the contact angles for thousands of latex particles at an oil/water interface. Furthermore, these measurements are dynamic, allowing the observation of the particle contact angle with high temporal resolution, resulting in hundreds of thousands of individual contact angle measurements. The contact angle has been found to fit a normal distribution with a standard deviation of 19.3°, which is much larger than previously recorded. Furthermore, the technique used allows the effect of measurement error, constrained interfacial diffusion, and particle property variation on the contact angle distribution to be individually evaluated. Because of the ability to measure the contact angle noninvasively, the results provide previously unobtainable, unique data on the dynamics and distribution of the adsorbed particles' contact angle.

  9. Determination of mercury and selenium in herbal medicines and hair by using a nanometer TiO{sub 2}-coated quartz tube atomizer and hydride generation atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shun-Xing, E-mail: lishunxing@fjzs.edu.cn [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science (Zhangzhou Normal University), Zhangzhou 363000 (China); Zheng, Feng-Ying [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Fujian Province University Key Laboratory of Analytical Science (Zhangzhou Normal University), Zhangzhou 363000 (China); Cai, Shu-Jie; Cai, Tian-Shou [Department of Chemistry and Environmental Science, Zhangzhou Normal University, Zhangzhou 363000 (China)

    2011-05-15

    The nanometer TiO{sub 2} particle was coated onto the inner wall of a T-shaped quartz tube atomizer (QTA) and then was used as a new atomizer (NT-QTA) for the determination of Hg and Se by hydride generation atomic absorption spectrometry (HGAAS). After coating 67.4 mg TiO{sub 2} on a quartz tube, the analytical performance of NT-QTA-HGAAS was compared to conventional QTA-HGAAS and it was improved as follows: (a) the linear range of the calibration curves was expanded from 10.0-80.0 ng mL{sup -1} to 5.0-150.0 ng mL{sup -1} for Hg, and from 10.0-70.0 ng mL{sup -1} to 5.0-100.0 ng mL{sup -1} for Se; (b) the characteristic concentration of was decreased from 2.8 ng mL{sup -1}/1% to 1.1 ng mL{sup -1}/1% for Hg and from 1.2 ng mL{sup -1}/1% to 0.8 ng mL{sup -1}/1% for Se; and (c) the interference from the coexistence of As on the determination of Hg and Se could be eliminated. The achieved technique was applied for the determination of Hg and Se in herbal medicines and hair.

  10. Biosynthesis of silver fine particles and particles decorated with nanoparticles using the extract of Illicium verum (star anise) seeds.

    Science.gov (United States)

    Luna, Carlos; Chávez, V H G; Barriga-Castro, Enrique Díaz; Núñez, Nuria O; Mendoza-Reséndez, Raquel

    2015-04-15

    Given the upsurge of new technologies based on nanomaterials, the development of sustainable methods to obtain functional nanostructures has become an imperative task. In this matter, several recent researches have shown that the biodegradable natural antioxidants of several plant extracts can be used simultaneously as reducing and stabilizing agents in the wet chemical synthesis of metallic nanoparticles, opening new opportunities to design greener synthesis. However, the challenge of these new techniques is to produce stable colloidal nanoparticles with controlled particle uniformity, size, shape and aggregation state, in similar manner than the well-established synthetic methods. In the present work, colloidal metallic silver nanoparticles have been synthesized using silver nitrate and extracts of Illicium verum (star anise) seeds at room temperature in a facile one-step procedure. The resulting products were colloidal suspensions of two populations of silver nanoparticles, one of them with particle sizes of few nanometers and the other with particles of tens of nm. Strikingly, the variation of the AgNO3/extract weight ratio in the reaction medium yielded to the variation of the spatial distribution of the nanoparticles: high AgNO3/extract concentration ratios yielded to randomly dispersed particles, whereas for lower AgNO3/extract ratios, the biggest particles appeared coated with the finest nanoparticles. This biosynthesized colloidal system, with controlled particle aggregation states, presents plasmonic and SERS properties with potential applications in molecular sensors and nanophotonic devices. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Effect of Grade Retention in First Grade on Psychosocial Outcomes

    OpenAIRE

    Wu, Wei; West, Stephen G.; Hughes, Jan N.

    2010-01-01

    In a 4-year longitudinal study, the authors investigated effects of retention in first grade on children’s externalizing and internalizing behaviors; social acceptance; and behavioral, cognitive, and affective engagement. From a large multiethnic sample (n = 784) of children below the median on literacy at school entrance, 124 retained children were matched with 251 promoted children on the basis of propensity scores (probability of being retained in first grade estimated from 72 baseline var...

  12. Fabrication and characteristics of alumina-iron functionally graded materials

    DEFF Research Database (Denmark)

    He, Zeming; Ma, J.; Tan, G.E.B.

    2009-01-01

    . The microstructure and the composition of the prepared component were studied, and its flexural strength, fracture toughness, and fracture energy were tested and evaluated. The relative density and the Vickers hardness of each layer in the graded material were also measured. The correlation between microstructure...... and composition and mechanical properties was discussed. Flat, crack-free, and relatively high-density gradient components were obtained from this work. Compared to monolithic alumina ceramic, the remarkable improvement on fracture toughness and fracture energy of the investigated graded material system......In the present work, five-layered alumina–iron functionally graded materials (FGMs) were fabricated via a simple route of die pressing and pressureless sintering. The shrinkage differences among the layers in the FGM were minimized by particle size selection and processing control...

  13. Hypersymmetry: A Z3-graded generalization of supersymmetry

    International Nuclear Information System (INIS)

    Abramov, V.; Kerner, R.; Le Roy, B.

    1997-01-01

    We propose a generalization of non-commutative geometry and gauge theories based on ternary Z 3 -graded structures. In the new algebraic structures we define, all products of two entities are left free, the only constraining relations being imposed on ternary products. These relations reflect the action of the Z 3 -group, which may be either trivial, i.e., abc=bca=cab, generalizing the usual commutativity, or non-trivial, i.e., abc=jbca, with j=e (2πi)/3 . The usual Z 2 -graded structures such as Grassmann, Lie, and Clifford algebras are generalized to the Z 3 -graded case. Certain suggestions concerning the eventual use of these new structures in physics of elementary particles and fields are exposed. copyright 1997 American Institute of Physics

  14. Particle kickers

    CERN Multimedia

    Antonella Del Rosso

    2014-01-01

    These devices are designed to provide a current pulse of 5000 Amps which will in turn generate a fast magnetic pulse that steers the incoming beam into the LHC. Today, the comprehensive upgrade of the LHC injection kicker system is entering its final stages. The upgraded system will ensure the LHC can be refilled without needing to wait for the kicker magnets to cool, thus enhancing the performance of the whole accelerator.   An upgraded kicker magnet in its vacuum tank, with an upgraded beam screen. The LHC is equipped with two kicker systems installed at the injection points (near points 2 and 8, see schematic diagram) where the particle beams coming from the SPS are injected into the accelerator’s orbit. Each system comprises four magnets and four pulse generators in which the field rises to 0.12 Tesla in less than 900 nanoseconds and for a duration of approximately 8 microseconds. Although the injection kickers only pulse 12 times to fill the LHC up with beam, the LHC beam circ...

  15. Characterization of Anisotropic Behavior for High Grade Pipes

    Science.gov (United States)

    Yang, Kun; Huo, Chunyong; Ji, Lingkang; Li, Yang; Zhang, Jiming; Ma, Qiurong

    With the developing requirement of nature gas, the property needs of steel for pipe line are higher and higher, especially in strength and toughness. It is necessary to improve the steel grade in order to ensure economic demand and safety. However, with the rise of steel grade, the differences on properties in different orientations (anisotropic behaviors) become more and more obvious after the process of hot rolling, which may affect the prediction of fracture for the pipes seriously (Thinking of isotropic mechanical properties for material in traditional predict way). In order to get the reason for anisotropic mechanics, a series of tests are carried out for high grade steel pipes, including not only mechanical properties but also microstructures. Result indicates that there are obviously anisotropic behaviors for high grade steel pipes in two orientations (rolling orientation and transverse orientation). Strength is better in T orientation because Rm is higher and Rt 0.5 rises more in T orientation, and toughness is better in L orientation because of the higher Akv and SA in L orientation under a same temperature. Banded structures are formed in T orientation, and the spatial distribution of inclusion and precipitated phases are different in T, L and S orientation. The anisotropic arrangement for the matrix in space (banded structures), which is formed after the process of hot rolling, may affect the mechanical properties in different orientation. Moreover, the elasticity modulus of particles is different from the elasticity modulus of matrix, deformation between particles and matrix may cause stress concentration, and damage forms in this place. Because of the different distribution of particles in space, the level of damage is anisotropic in different orientations, and the anisotropic mechanical properties occur finally. Therefore, the anisotropic mechanical properties are determined by the anisotropic microstructures, both the anisotropic of matrix and the

  16. Resolving three-dimensional shape of sub-50 nm wide lines with nanometer-scale sensitivity using conventional optical microscopes

    International Nuclear Information System (INIS)

    Attota, Ravikiran; Dixson, Ronald G.

    2014-01-01

    We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

  17. Gender discrimination in exam grading?

    DEFF Research Database (Denmark)

    Rangvid, Beatrice Schindler

    2018-01-01

    Girls, on average, obtain higher test scores in school than boys, and recent research suggests that part of this difference may be due to discrimination against boys in grading. This bias is consequential if admission to subsequent education programs is based on exam scores. This study assesses t...... tendencies are in accordance with statistical discrimination as a mechanism for grading bias in essay writing and with gender-stereotyped beliefs of math being a male domain....... are scored twice (blind and non-blind). Both strategies use difference-in-differences methods. Although imprecisely estimated, the point estimates indicate a blind grading advantage for boys in essay writing of approximately 5-8% SD, corresponding to 9-15% of the gender gap in essay exam grades. The effect...

  18. Progressive problems higher grade physics

    CERN Document Server

    Kennedy, William

    2001-01-01

    This book fully covers all three Units studied in Scotland's Higher Grade Physics course, providing a systematic array of problems (from the simplest to the most difficult) to lead variously abled pupils to examination success.

  19. Grade 6 Science Curriculum Specifications.

    Science.gov (United States)

    Alberta Dept. of Education, Edmonton. Curriculum Branch.

    This material describes curriculum specifications for grade 6 science in Alberta. Emphases recommended are: (1) process skills (50%); (2) psychomotor skills (10%); (3) attitudes (10%); and (4) subject matter (30%). Priorities within each category are identified. (YP)

  20. Improving GRADE evidence tables part 2

    DEFF Research Database (Denmark)

    Langendam, Miranda; Carrasco-Labra, Alonso; Santesso, Nancy

    2016-01-01

    OBJECTIVES: The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) working group has developed GRADE evidence profiles (EP) and summary of findings (SoF) tables to present evidence summaries in systematic reviews, clinical guidelines, and health technology assessments. Exp...

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

    Science.gov (United States)

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

    2006-03-15

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

  2. Particle processing technology

    Science.gov (United States)

    Sakka, Yoshio

    2014-02-01

    In recent years, there has been strong demand for the development of novel devices and equipment that support advanced industries including IT/semiconductors, the environment, energy and aerospace along with the achievement of higher efficiency and reduced environmental impact. Many studies have been conducted on the fabrication of innovative inorganic materials with novel individual properties and/or multifunctional properties including electrical, dielectric, thermal, optical, chemical and mechanical properties through the development of particle processing. The fundamental technologies that are key to realizing such materials are (i) the synthesis of nanoparticles with uniform composition and controlled crystallite size, (ii) the arrangement/assembly and controlled dispersion of nanoparticles with controlled particle size, (iii) the precise structural control at all levels from micrometer to nanometer order and (iv) the nanostructural design based on theoretical/experimental studies of the correlation between the local structure and the functions of interest. In particular, it is now understood that the application of an external stimulus, such as magnetic energy, electrical energy and/or stress, to a reaction field is effective in realizing advanced particle processing [1-3]. This special issue comprises 12 papers including three review papers. Among them, seven papers are concerned with phosphor particles, such as silicon, metals, Si3N4-related nitrides, rare-earth oxides, garnet oxides, rare-earth sulfur oxides and rare-earth hydroxides. In these papers, the effects of particle size, morphology, dispersion, surface states, dopant concentration and other factors on the optical properties of phosphor particles and their applications are discussed. These nanoparticles are classified as zero-dimensional materials. Carbon nanotubes (CNT) and graphene are well-known one-dimensional (1D) and two-dimensional (2D) materials, respectively. This special issue also

  3. Electrospraying and ultraviolet light curing of nanometer-thin polydimethylsiloxane membranes for low-voltage dielectric elastomer transducers

    Science.gov (United States)

    Osmani, Bekim; Töpper, Tino; Siketanc, Matej; Kovacs, Gabor M.; Müller, Bert

    2017-04-01

    Dielectric elastomer transducers (DETs) have attracted interest as actuators, sensors, and even as self-sensing actuators for applications in medicine, soft robotics, and microfluidics. To reach strains of more than 10 %, they currently require operating voltages of several hundred volts. In medical applications for artificial muscles, however, their operation is limited to a very few tens of volts, which implies high permittivity materials and thin-film structures. Such micro- or nanostructures can be prepared using electro-spraying, a cost-effective technique that allows upscaling using multiple nozzles for the fabrication of silicone films down to nanometer thickness. Deposition rates of several micrometers per hour have already been reached. It has been recently demonstrated that such membranes can be fabricated by electro-spraying and subsequent ultraviolet light irradiation. Herein, we introduce a relatively fast deposition of a dimethyl silicone copolymer fluid that contains mercaptopropyl side chains in addition to the methyl groups. Its elastic modulus was tuned with the irradiation dose of the 200 W Hg-Xe lamp. We also investigated the formation of elastomer films, using polymer concentrations in ethyl acetate of 1, 2, 5 and 10 vol%. After curing, the surface roughness was measured by means of atomic force microscopy. This instrument also enabled us to determine the average elastic modulus out of, for example, 400 nanoindentation measurements, using a spherical tip with a radius of 500 nm. The elastomer films were cured for a period of less than one minute, a speed that makes it feasible to combine electro-spraying and in situ curing in a single process step for fabricating low-voltage, multilayer DETs.

  4. X-ray diffraction and high resolution transmission electron microscopy characterization of intermetallics formed in Fe/Ti nanometer-scale multilayers during thermal annealing

    International Nuclear Information System (INIS)

    Wu, Z.L.; Peng, T.X.; Cao, B.S.; Lei, M.K.

    2009-01-01

    Intermetallics formation in the Fe/Ti nanometer-scale multilayers magnetron-sputtering deposited on Si(100) substrate during thermal annealing at 623-873 K was investigated by using small and wide angle X-ray diffraction and cross-sectional high-resolution transmission electron microscopy. The Fe/Ti nanometer-scale multilayers were constructed with bilayer thickness of 16.2 nm and the sublayer thickness ratio of 1:1. At the annealing temperature of 623 K, intermetallics FeTi were formed by nucleation at the triple joins of α-Fe(Ti)/α-Ti interface and α-Ti grain boundary with an orientational correlation of FeTi(110)//α-Ti(100) and FeTi[001]//α-Ti[001] to adjacent α-Ti grains. The lateral growth of intermetallics FeTi which is dependent on the diffusion path of Ti led to a coalescence into an intermetallic layer. With an increase in the annealing temperature, intermetallics Fe 2 Ti were formed between the intermetallics FeTi and the excess Fe due to the limitation of Fe and Ti atomic concentrations, resulting in the coexistence of intermetallics FeTi and Fe 2 Ti. It was found that the low energy interface as well as the dominant diffusion path constrained the nucleation and growth of intermetallics during interfacial reaction in the nanometer-scale metallic multilayers.

  5. Study of nanometer-level precise phase-shift system used in electronic speckle shearography and phase-shift pattern interferometry

    Science.gov (United States)

    Jing, Chao; Liu, Zhongling; Zhou, Ge; Zhang, Yimo

    2011-11-01

    The nanometer-level precise phase-shift system is designed to realize the phase-shift interferometry in electronic speckle shearography pattern interferometry. The PZT is used as driving component of phase-shift system and translation component of flexure hinge is developed to realize micro displacement of non-friction and non-clearance. Closed-loop control system is designed for high-precision micro displacement, in which embedded digital control system is developed for completing control algorithm and capacitive sensor is used as feedback part for measuring micro displacement in real time. Dynamic model and control model of the nanometer-level precise phase-shift system is analyzed, and high-precision micro displacement is realized with digital PID control algorithm on this basis. It is proved with experiments that the location precision of the precise phase-shift system to step signal of displacement is less than 2nm and the location precision to continuous signal of displacement is less than 5nm, which is satisfied with the request of the electronic speckle shearography and phase-shift pattern interferometry. The stripe images of four-step phase-shift interferometry and the final phase distributed image correlated with distortion of objects are listed in this paper to prove the validity of nanometer-level precise phase-shift system.

  6. Cracks in functionally graded materials

    International Nuclear Information System (INIS)

    Bahr, H.-A.; Balke, H.; Fett, T.; Hofinger, I.; Kirchhoff, G.; Munz, D.; Neubrand, A.; Semenov, A.S.; Weiss, H.-J.; Yang, Y.Y.

    2003-01-01

    The weight function method is described to analyze the crack growth behavior in functionally graded materials and in particular materials with a rising crack growth resistance curve. Further, failure of graded thermal barrier coatings (TBCs) under cyclic surface heating by laser irradiation is modeled on the basis of fracture mechanics. The damage of both graded and non-graded TBCs is found to develop in several distinct stages: vertical cracking→delamination→blistering→spalling. This sequence can be understood as an effect of progressive shrinkage due to sintering and high-temperature creep during thermal cycling, which increases the energy-release rate for vertical cracks which subsequently turn into delamination cracks. The results of finite element modeling, taking into account the TBC damage mechanisms, are compatible with experimental data. An increase of interface fracture toughness due to grading and a decrease due to ageing have been measured in a four-point bending test modified by a stiffening layer. Correlation with the damage observed in cyclic heating is discussed. It is explained in which way grading is able to reduce the damage

  7. Graded/Gradient Porous Biomaterials

    Directory of Open Access Journals (Sweden)

    Xigeng Miao

    2009-12-01

    Full Text Available Biomaterials include bioceramics, biometals, biopolymers and biocomposites and they play important roles in the replacement and regeneration of human tissues. However, dense bioceramics and dense biometals pose the problem of stress shielding due to their high Young’s moduli compared to those of bones. On the other hand, porous biomaterials exhibit the potential of bone ingrowth, which will depend on porous parameters such as pore size, pore interconnectivity, and porosity. Unfortunately, a highly porous biomaterial results in poor mechanical properties. To optimise the mechanical and the biological properties, porous biomaterials with graded/gradient porosity, pores size, and/or composition have been developed. Graded/gradient porous biomaterials have many advantages over graded/gradient dense biomaterials and uniform or homogenous porous biomaterials. The internal pore surfaces of graded/gradient porous biomaterials can be modified with organic, inorganic, or biological coatings and the internal pores themselves can also be filled with biocompatible and biodegradable materials or living cells. However, graded/gradient porous biomaterials are generally more difficult to fabricate than uniform or homogenous porous biomaterials. With the development of cost-effective processing techniques, graded/gradient porous biomaterials can find wide applications in bone defect filling, implant fixation, bone replacement, drug delivery, and tissue engineering.

  8. Preparation and Characterization of Stable α-Synuclein Lipoprotein Particles.

    Science.gov (United States)

    Eichmann, Cédric; Campioni, Silvia; Kowal, Julia; Maslennikov, Innokentiy; Gerez, Juan; Liu, Xiaoxia; Verasdonck, Joeri; Nespovitaya, Nadezhda; Choe, Senyon; Meier, Beat H; Picotti, Paola; Rizo, Josep; Stahlberg, Henning; Riek, Roland

    2016-04-15

    Multiple neurodegenerative diseases are caused by the aggregation of the human α-Synuclein (α-Syn) protein. α-Syn possesses high structural plasticity and the capability of interacting with membranes. Both features are not only essential for its physiological function but also play a role in the aggregation process. Recently it has been proposed that α-Syn is able to form lipid-protein particles reminiscent of high-density lipoproteins. Here, we present a method to obtain a stable and homogeneous population of nanometer-sized particles composed of α-Syn and anionic phospholipids. These particles are called α-Syn lipoprotein (nano)particles to indicate their relationship to high-density lipoproteins formed by human apolipoproteins in vivo and of in vitro self-assembling phospholipid bilayer nanodiscs. Structural investigations of the α-Syn lipoprotein particles by circular dichroism (CD) and magic angle solid-state nuclear magnetic resonance (MAS SS-NMR) spectroscopy establish that α-Syn adopts a helical secondary structure within these particles. Based on cryo-electron microscopy (cryo-EM) and dynamic light scattering (DLS) α-Syn lipoprotein particles have a defined size with a diameter of ∼23 nm. Chemical cross-linking in combination with solution-state NMR and multiangle static light scattering (MALS) of α-Syn particles reveal a high-order protein-lipid entity composed of ∼8-10 α-Syn molecules. The close resemblance in size between cross-linked in vitro-derived α-Syn lipoprotein particles and a cross-linked species of endogenous α-Syn from SH-SY5Y human neuroblastoma cells indicates a potential functional relevance of α-Syn lipoprotein nanoparticles. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Hardwood log grades and lumber grade yields for factory lumber logs

    Science.gov (United States)

    Leland F. Hanks; Glenn L. Gammon; Robert L. Brisbin; Everette D. Rast

    1980-01-01

    The USDA Forest Service Standard Grades for Hardwood Factory Lumber Logs are described, and lumber grade yields for 16 species and 2 species groups are presented by log grade and log diameter. The grades enable foresters, log buyers, and log sellers to select and grade those log suitable for conversion into standard factory grade lumber. By using the apropriate lumber...

  10. 7 CFR 810.2204 - Grades and grade requirements for wheat.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Grades and grade requirements for wheat. 810.2204... OFFICIAL UNITED STATES STANDARDS FOR GRAIN United States Standards for Wheat Principles Governing the Application of Standards § 810.2204 Grades and grade requirements for wheat. (a) Grades and grade requirements...

  11. Fermilab | Science | Particle Physics

    Science.gov (United States)

    Photos and videos Latest news For the media Particle Physics Neutrinos Fermilab and the LHC Dark matter initiatives Research and development Key discoveries Benefits of particle physics Particle Accelerators society Particle Physics 101 Science of matter, energy, space and time How particle physics discovery

  12. Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

    Science.gov (United States)

    Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

    2003-03-01

    Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

  13. Particle theory and cosmology

    International Nuclear Information System (INIS)

    Gaisser, T.K.; Shafi, Q.; Barr, S.M.; Seckel, D.; Rusjan, E.; Fletcher, R.S.

    1991-01-01

    This report discusses research of professor at Bartol research institute in the following general areas: particle phenomenology and non-accelerator physics; particle physics and cosmology; theories with higher symmetry; and particle astrophysics and cosmology

  14. Fiscal 1998 research report on micro-particle control process technology; 1998 nendo micro ryushi seigyo process gijutsu no chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    For establishment of process technology realizing control of forms and structures of micro-particles on practical equipment, research was made on related elementary technologies and current technologies. The research was promoted aiming at synthesis of micro-particles from nanometer to micrometer in size and their application to functional materials, establishment of the methodology for correlating the microstructure and function of micro-particle materials with fabrication process, and establishment of a common-base technology system in chemical technology aiming at fabrication of functional materials. As for the common- base technology, to clarify its importance, research was made on the fabrication method and dispersion mechanism of nano- particles, particle arraying method by coating, device fabrication technique by coating, and one-step synthesis and coating of nano-particles. As for the project research, synthesis of monodispersed nano-particles at large production rates, fabrication of thin films and bulk materials by arraying and coating. (NEDO)

  15. Particle-based simulation of charge transport in discrete-charge nano-scale systems: the electrostatic problem.

    Science.gov (United States)

    Berti, Claudio; Gillespie, Dirk; Eisenberg, Robert S; Fiegna, Claudio

    2012-02-16

    The fast and accurate computation of the electric forces that drive the motion of charged particles at the nanometer scale represents a computational challenge. For this kind of system, where the discrete nature of the charges cannot be neglected, boundary element methods (BEM) represent a better approach than finite differences/finite elements methods. In this article, we compare two different BEM approaches to a canonical electrostatic problem in a three-dimensional space with inhomogeneous dielectrics, emphasizing their suitability for particle-based simulations: the iterative method proposed by Hoyles et al. and the Induced Charge Computation introduced by Boda et al.

  16. Histological and histomorphometric evaluation of implant with nanometer scale and oxidized surface. in vitro and in vivo study.

    Science.gov (United States)

    Corvino, V; Iezzi, G; Trubiani, O; Traini, T; Piattelli, M

    2012-01-01

    The biological fixation of an implant to bone is influenced by numerous factors, including surface chemistry and surface topography. Various methods have been developed to create rough implant surfaces in order to improve the clinical performance of implants and to guarantee a stable mechanical bone-implant interface. Anodic oxidation is a dental implant surface modification technique that results in oxide layer growth up to a thickness of 1–10 micron. The purpose of this study was to evaluate the performance of the surface through the osteoblasts cells growth and the influence of oxidixed surface on BIC percent, in the human posterior maxilla after 2 months of unloaded healing. In vitro commercially available primary human osteoblasts (NHOst) from both femur and tibia of different donor systems (Lonza Walkersville Inc, Walkersville, MD, USA) were grown in Osteoblast Growth Media (OBM) (Lonza). Osteogenic differentiation was induced for a period of 4 weeks by the OGM medium (OBM basal medium supplemented with 200nM of hydrocortisone-21-hemisuccinate and 7.5 mM of glycerophosphate). The viability of NHOst cells seeded test A and B was measured by the quantitative colorimetric MTT (3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2Htetrazoliumbromide test) (Promega, Milan, Italy). One custom-made 2 x 10-mm site evaluation implant (SEI) with nanometer scale and oxidized surface (test) ( Evo Plan 1 Health s.r.l. - Amaro, UD, Italy), and one SEI with hydroxyapatite sandblasted surface (control) (Osseogrip Plan 1 Health s.r.l. – Amaro, UD, Italy), were placed in the posterior maxilla of 15 patients. Patients received one of each type of SEI placed on controlateral side. The proliferation rate studied by the MTT assay showed that during the incubation time, starting at 24 h, an increased proliferation rate was evident in Test B respect to Test A. After 2 months of unloaded healing BIC percent was significantly higher in oxidized implants. BIC percent mean values for the

  17. Functionally Graded Mo sintered steels

    Directory of Open Access Journals (Sweden)

    Manuel Cisneros-Belmonte

    2016-12-01

    Full Text Available Functionally graded materials (FGM, the multi-materials, strive to satisfy the numerous requirements demanded of parts in a given combination of compositions and microstructures. The required material compatibility lead the manufacturing process and the achieving of an interface, not always diffuse. Powder metallurgy is one of the techniques used in manufacturing functionally graded materials, in particular the compaction matrix of the possible techniques for forming these materials. In this paper, a process of forming a functionally graded steel based on the use of a high molybdenum steel with cooper and other steel with copper, without molybdenum, is proposed with the aim of concentrating this element to the surface of the workpiece, increasing the mechanical strength. The study is completed with the evaluation of physical properties (density and porosity distribution, mechanical properties (hardness, tensile strength and elongation and microstructural analysis by optical and scanning electron microscopy.

  18. 7 CFR 51.304 - Combination grades.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... Standards for Grades of Apples Grades § 51.304 Combination grades. (a) Combinations of the above grades may...

  19. On-Demand Grades: The Effect of Online Grade Book Access on Student Mastery and Performance Goal Orientations, Grade Orientation, Academic Self Efficacy, and Grades

    Science.gov (United States)

    Seldow, Adam Lowell

    2010-01-01

    With the widespread growth of broadband Internet access, teachers, and in many cases, schools and school districts are transitioning from traditional paper-based grade books to student accessible online (Web-based) grade books. Online grade books offer students 24/7, on demand access to grades and various other student data, and have the potential…

  20. Functionally Graded Material: An overview

    CSIR Research Space (South Africa)

    Mahamood, RM

    2012-07-01

    Full Text Available -3146. [50] X. Jin, L. Wu, L. Guo, H. Yu, and Y. Sun, ?Experimental investigation of the mixed-mode crack propagation in ZrO2/NiCr functionally graded materials,? Engineering Fracture Mechanics, vol. 76(12), (2009), pp. 1800-1810. [51] Z. Cheng, D. Gao... by stable crack growth,? Engineering Fracture Mechanics, vol.72(15), (2005), pp. 2359-2372. [47] Z.-H. Jin, and R.H. Dodds Jr, ?Crack growth resistance behavior of a functionally graded material: computational studies,? Engineering Fracture Mechanics...

  1. On the union of graded prime ideals

    Directory of Open Access Journals (Sweden)

    Uregen Rabia Nagehan

    2016-01-01

    Full Text Available In this paper we investigate graded compactly packed rings, which is defined as; if any graded ideal I of R is contained in the union of a family of graded prime ideals of R, then I is actually contained in one of the graded prime ideals of the family. We give some characterizations of graded compactly packed rings. Further, we examine this property on h – Spec(R. We also define a generalization of graded compactly packed rings, the graded coprimely packed rings. We show that R is a graded compactly packed ring if and only if R is a graded coprimely packed ring whenever R be a graded integral domain and h – dim R = 1.

  2. 25th Anniversary Article: Polymer-Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

    KAUST Repository

    Srivastava, Samanvaya

    2013-12-09

    Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom-up synthesis strategies for understanding and controlling nanoparticle dispersion in polymers are reviewed. Applications of these approaches for creating polymer-particle composite electrolytes and electrodes for energy storage are also considered. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. 7 CFR 810.404 - Grades and grade requirements for corn.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Grades and grade requirements for corn. 810.404... OFFICIAL UNITED STATES STANDARDS FOR GRAIN United States Standards for Corn Principles Governing the Application of Standards § 810.404 Grades and grade requirements for corn. Grade Minimum test weight per...

  4. 7 CFR 810.1804 - Grades and grade requirements for sunflower seed.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 7 2010-01-01 2010-01-01 false Grades and grade requirements for sunflower seed. 810... AGRICULTURE OFFICIAL UNITED STATES STANDARDS FOR GRAIN United States Standards for Sunflower Seed Principles Governing the Application of Standards § 810.1804 Grades and grade requirements for sunflower seed. Grade...

  5. Attendance Policies and Student Grades

    Science.gov (United States)

    Risen, D. Michael

    2007-01-01

    The details described in this case study examine the issues related to attendance policies and how such policies might be legally used to affect student grades. Concepts discussed should cause graduate students in educational administration to reflect on the issues presented from various points of view when the students complete an analysis of the…

  6. Grading Rubrics: Hoopla or Help?

    Science.gov (United States)

    Howell, Rebecca J.

    2014-01-01

    The purpose of the study was to offer some quantitative, multivariate evidence concerning the impact of grading rubric use on academic outcome among American higher education students. Using a pre-post, quasi-experimental research design, cross-sectional data were derived from undergraduates enrolled in an elective during spring and fall 2009 at…

  7. Transportation: Grade 8. Cluster IV.

    Science.gov (United States)

    Calhoun, Olivia H.

    A curriculum guide for grade 8, the document is devoted to the occupational cluster "Transportation." It is divided into five units: surface transportation, interstate transportation, air transportation, water transportation, and subterranean transportation (the Metro). Each unit is introduced by a statement of the topic, the unit's…

  8. The relations of particles

    International Nuclear Information System (INIS)

    Okun, L.B.

    1991-01-01

    This book presents papers on elementary particle physics, relations between various particles, and the connections between particle physics with other branches of physics. The papers include: Contemporary status and prospects of high-energy physics; Particle physics prospects; and High energy physics

  9. Particle adhesion and removal

    CERN Document Server

    Mittal, K L

    2015-01-01

    The book provides a comprehensive and easily accessible reference source covering all important aspects of particle adhesion and removal.  The core objective is to cover both fundamental and applied aspects of particle adhesion and removal with emphasis on recent developments.  Among the topics to be covered include: 1. Fundamentals of surface forces in particle adhesion and removal.2. Mechanisms of particle adhesion and removal.3. Experimental methods (e.g. AFM, SFA,SFM,IFM, etc.) to understand  particle-particle and particle-substrate interactions.4. Mechanics of adhesion of micro- and  n

  10. Review of particle properties. Particle Data Group

    International Nuclear Information System (INIS)

    1978-04-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Rev. Mod. Phys. 48 (1976) No. 2, Part II; and Supplement, Phys. Lett. 68B (1977) 1]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available

  11. Direct observation of nanometer-scale amorphous layers and oxide crystallites at grain boundaries in polycrystalline Sr1−xKxFe2As2 superconductors

    KAUST Repository

    Wang, Lei

    2011-06-01

    We report here an atomic resolution study of the structure and composition of the grain boundaries in polycrystallineSr0.6K0.4Fe2As2superconductor. A large fraction of grain boundaries contain amorphous layers larger than the coherence length, while some others contain nanometer-scale crystallites sandwiched in between amorphous layers. We also find that there is significant oxygen enrichment at the grain boundaries. Such results explain the relatively low transport critical current density (Jc) of polycrystalline samples with respect to that of bicrystal films.

  12. Smartphone-based grading of apple quality

    Science.gov (United States)

    Li, Xianglin; Li, Ting

    2018-02-01

    Apple quality grading is a critical issue in apple industry which is one economical pillar of many countries. Artificial grading is inefficient and of poor accuracy. Here we proposed to develop a portable, convenient, real-time, and low cost method aimed at grading apple. Color images of the apples were collected with a smartphone and the grade of sampled apple was assessed by a customized smartphone app, which offered the functions translating RGB color values of the apple to color grade and translating the edge of apple image to weight grade. The algorithms are based on modeling with a large number of apple image at different grades. The apple grade data evaluated by the smartphone are in accordance with the actual data. This study demonstrated the potential of smart phone in apple quality grading/online monitoring at gathering and transportation stage for apple industry.

  13. Surface features on Sahara soil dust particles made visible by atomic force microscope (AFM phase images

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2008-10-01

    Full Text Available We show that atomic force microscopy (AFM phase images can reveal surface features of soil dust particles, which are not evident using other microscopic methods. The non-contact AFM method is able to resolve topographical structures in the nanometer range as well as to uncover repulsive atomic forces and attractive van der Waals' forces, and thus gives insight to surface properties. Though the method does not allow quantitative assignment in terms of chemical compound description, it clearly shows deposits of distinguishable material on the surface. We apply this technique to dust aerosol particles from the Sahara collected over the Atlantic Ocean and describe micro-features on the surfaces of such particles.

  14. Au-Nano-particle Deposition on alumina surfaces for environmental application-a density functional study

    International Nuclear Information System (INIS)

    Chatterjee, Abhijit

    2009-01-01

    Full text: It has been found that nanometer size gold particles on different oxide supports can act as catalysts, suggestions include quantum size effects, availability of low coordinated sites, and strain or combined effects of the gold particles and the oxide support. From photo dissociation spectroscopy and theory it has been inferred that the 2D / 3D structural transition occurs between five and seven atoms depending on charge state neutrals and singly positively charged ions. Here we will look into the interaction of gold particles over different sites of the aluminum -oxide surface to tune the catalytic activity of the novel material using first principle periodic calculations and compare them with the reactivity index to formulate a priori rule for metal cluster interaction. The catalytic application is aimed to CO adsorption type reactions for a greener environment. (author)

  15. Nanoscale particles in technological processes of beneficiation

    Directory of Open Access Journals (Sweden)

    Sergey I. Popel

    2014-04-01

    Full Text Available Background: Cavitation is a rather common and important effect in the processes of destruction of nano- and microscale particles in natural and technological processes. A possible cavitation disintegration of polymineral nano- and microparticles, which are placed into a liquid, as a result of the interaction of the particles with collapsed cavitation bubbles is considered. The emphasis is put on the cavitation processes on the interface between liquid and fine solid particles, which is suitable for the description of the real situations.Results: The results are illustrated for the minerals that are most abundant in gold ore. The bubbles are generated by shock loading of the liquid heated to the boiling temperature. Possibilities of cavitation separation of nano- and microscale monomineral fractions from polymineral nano- and microparticles and of the use of cavitation for beneficiation are demonstrated.Conclusion: The cavitation disintegration mechanism is important because the availability of high-grade deposits in the process of mining and production of noble metals is decreasing. This demands for an enhancement of the efficiency in developing low-grade deposits and in reprocessing ore dumps and tailings, which contain a certain amount of noble metals in the form of finely disseminated fractions. The cavitation processes occuring on the interface between liquid and fine solid particles are occasionally more effective than the bulk cavitation processes that were considered earlier.

  16. Occurrence of particle debris field during focused Ga ion beam milling of glassy carbon

    Energy Technology Data Exchange (ETDEWEB)

    Hu Qin [Centre for Industrial Photonics, Institute for Manufacturing, Department of Engineering, University of Cambridge, Alan Reece Building, 17 Charles Babbage Road, Cambridge, CB3 0FS (United Kingdom); O' Neill, William, E-mail: wo207@eng.cam.ac.uk [Centre for Industrial Photonics, Institute for Manufacturing, Department of Engineering, University of Cambridge, Alan Reece Building, 17 Charles Babbage Road, Cambridge, CB3 0FS (United Kingdom)

    2010-08-01

    To explore the machining characteristics of glassy carbon by focused ion beam (FIB), particles induced by FIB milling on glassy carbon have been studied in the current work. Nano-sized particles in the range of tens of nanometers up to 400 nm can often be found around the area subject to FIB milling. Two ion beam scanning modes - slow single scan and fast repetitive scan - have been tested. Fewer particles are found in single patterns milled in fast repetitive scan mode. For a group of test patterns milled in a sequence, it was found that a greater number of particles were deposited around sites machined early in the sequence. In situ EDX analysis of the particles showed that they were composed of C and Ga. The formation of particles is related to the debris generated at the surrounding areas, the low melting point of gallium used as FIB ion source and the high contact angle of gallium on glassy carbon induces de-wetting of Ga and the subsequent formation of Ga particles. Ultrasonic cleaning can remove over 98% of visible particles. The surface roughness (R{sub a}) of FIB milled areas after cleaning is less than 2 nm.

  17. Occurrence of particle debris field during focused Ga ion beam milling of glassy carbon

    International Nuclear Information System (INIS)

    Hu Qin; O'Neill, William

    2010-01-01

    To explore the machining characteristics of glassy carbon by focused ion beam (FIB), particles induced by FIB milling on glassy carbon have been studied in the current work. Nano-sized particles in the range of tens of nanometers up to 400 nm can often be found around the area subject to FIB milling. Two ion beam scanning modes - slow single scan and fast repetitive scan - have been tested. Fewer particles are found in single patterns milled in fast repetitive scan mode. For a group of test patterns milled in a sequence, it was found that a greater number of particles were deposited around sites machined early in the sequence. In situ EDX analysis of the particles showed that they were composed of C and Ga. The formation of particles is related to the debris generated at the surrounding areas, the low melting point of gallium used as FIB ion source and the high contact angle of gallium on glassy carbon induces de-wetting of Ga and the subsequent formation of Ga particles. Ultrasonic cleaning can remove over 98% of visible particles. The surface roughness (R a ) of FIB milled areas after cleaning is less than 2 nm.

  18. Forces acting on a small particle in an acoustical field in a thermoviscous fluid.

    Science.gov (United States)

    Karlsen, Jonas T; Bruus, Henrik

    2015-10-01

    We present a theoretical analysis of the acoustic radiation force on a single small spherical particle, either a thermoviscous fluid droplet or a thermoelastic solid particle, suspended in a viscous and heat-conducting fluid medium. Within the perturbation assumptions, our analysis places no restrictions on the length scales of the viscous and thermal boundary-layer thicknesses δ(s) and δ(t) relative to the particle radius a, but it assumes the particle to be small in comparison to the acoustic wavelength λ. This is the limit relevant to scattering of ultrasound waves from nanometer- and micrometer-sized particles. For particles of size comparable to or smaller than the boundary layers, the thermoviscous theory leads to profound consequences for the acoustic radiation force. Not only do we predict forces orders of magnitude larger than expected from ideal-fluid theory, but for certain relevant choices of materials, we also find a sign change in the acoustic radiation force on different-sized but otherwise identical particles. These findings lead to the concept of a particle-size-dependent acoustophoretic contrast factor, highly relevant to acoustic separation of microparticles in gases, as well as to handling of nanoparticles in lab-on-a-chip systems.

  19. Elementary particle physics in early physics education

    CERN Document Server

    Wiener, Gerfried

    2017-01-01

    Current physics education research is faced with the important question of how best to introduce elementary particle physics in the classroom early on. Therefore, a learning unit on the subatomic structure of matter was developed, which aims to introduce 12-year-olds to elementary particles and fundamental interactions. This unit was iteratively evaluated and developed by means of a design-based research project with grade-6 students. In addition, dedicated professional development programmes were set up to instruct high school teachers about the learning unit and enable them to investigate its didactical feasibility. Overall, the doctoral research project led to successful results and showed the topic of elementary particle physics to be a viable candidate for introducing modern physics in the classroom. Furthermore, thanks to the design-based research methodology, the respective findings have implications for both physics education and physics education research, which will be presented during the PhD defen...

  20. Anaplasia and grading in medulloblastomas.

    Science.gov (United States)

    Eberhart, Charles G; Burger, Peter C

    2003-07-01

    The variable clinical outcomes of medulloblastoma patients have prompted a search for markers with which to tailor therapies to individuals. In this review, we discuss clinical, histological and molecular features that can be used in such treatment customization, focusing on how histopathological grading can impact both patient care and research on the molecular basis of CNS embryonal tumors. Medulloblastomas span a histological spectrum ending in overtly malignant large cell/anaplastic lesions characterized by increased nuclear size, marked cytological anaplasia, and increased mitotic and apoptotic rates. These "high-grade" lesions make up approximately one quarter of medulloblastomas, and recur and metastasize more frequently than tumors lacking anaplasia. We believe anaplastic change represents a type of malignant progression common to many medulloblastoma subtypes and to other CNS embryonal lesions as well. Correlation of these histological changes with the accumulation of genetic events suggests a model for the histological and molecular progression of medulloblastoma.

  1. Gradings on simple Lie algebras

    CERN Document Server

    Elduque, Alberto

    2013-01-01

    Gradings are ubiquitous in the theory of Lie algebras, from the root space decomposition of a complex semisimple Lie algebra relative to a Cartan subalgebra to the beautiful Dempwolff decomposition of E_8 as a direct sum of thirty-one Cartan subalgebras. This monograph is a self-contained exposition of the classification of gradings by arbitrary groups on classical simple Lie algebras over algebraically closed fields of characteristic not equal to 2 as well as on some nonclassical simple Lie algebras in positive characteristic. Other important algebras also enter the stage: matrix algebras, the octonions, and the Albert algebra. Most of the presented results are recent and have not yet appeared in book form. This work can be used as a textbook for graduate students or as a reference for researchers in Lie theory and neighboring areas.

  2. Grading of quality assurance requirements

    International Nuclear Information System (INIS)

    1991-01-01

    The present Manual provides guidance and illustrative examples for applying a method by which graded quality assurance requirements may be determined and adapted to the items and services of a nuclear power plant in conformance with the requirements of the IAEA Nuclear Safety Standards (NUSS) Code and Safety Guides on quality assurance. The Manual replaces the previous publication IAEA-TECDOC-303 on the same subject. Various methods of grading quality assurance are available in a number of Member States. During the development of the present Manual it was not considered practical to attempt to resolve the differences between those methods and it was preferred to identify and benefit from the good practices available in all the methods. The method presented in this Manual deals with the aspects of management, documentation, control, verification and administration which affect quality. 1 fig., 4 tabs

  3. Passive behavior of a bulk nanostructured 316L austenitic stainless steel consisting of nanometer-sized grains with embedded nano-twin bundles

    International Nuclear Information System (INIS)

    Li, Tianshu; Liu, Li; Zhang, Bin; Li, Ying; Yan, Fengkai; Tao, Nairong; Wang, Fuhui

    2014-01-01

    Highlights: • Nanometer-grains (NG) and bundles of nano-twins (NT) is synthesized in 316L. • (NG + NT) and NT enhance the concentration of active Fe Fe in the passive film. • (NG + NT) and NT enhance the passive ability. • A Cr 0 -enriched layer forms at the passive film/metal interface. - Abstract: The passive behavior of a bulk nanostructured 316L austenitic stainless steel consisting of nanometer-sized grains (NG) and nano-twin bundles (NT) are investigated. The electrochemical results indicate that the spontaneous passivation ability and growth rate of passive film are improved. The X-ray photoelectron spectroscopy (XPS) shows that a Cr 0 -enriched layer forms at the passive film/metal interface. More nucleation sites afforded by the nanostructures and the enhanced diffusion rate of charged species across the passive film are believed to be responsible for the improved passive ability. The PDM model is introduced to elaborate the microscopic process of passivation

  4. Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO2 transformation

    Science.gov (United States)

    Shanmugam, Ramasamy; Thamaraichelvan, Arunachalam; Ganesan, Tharumeya Kuppusamy; Viswanathan, Balasubramanian

    2017-02-01

    Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO2 to CO at an applied potential of -0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

  5. A compact, all-optical, THz wave generator based on self-modulation in a slab photonic crystal waveguide with a single sub-nanometer graphene layer.

    Science.gov (United States)

    Asadi, R; Ouyang, Z; Mohammd, M M

    2015-07-14

    We design a compact, all-optical THz wave generator based on self-modulation in a 1-D slab photonic crystal (PhC) waveguide with a single sub-nanometer graphene layer by using enhanced nonlinearity of graphene. It has been shown that at the bandgap edge of higher bands of a 1-D slab PhC, through only one sub-nanometer graphene layer we can obtain a compact, high modulation factor (about 0.98 percent), self-intensity modulator at a high frequency (about 0.6 THz) and low threshold intensity (about 15 MW per square centimeter), and further a compact, all-optical THz wave generator by integrating the self-modulator with a THz photodiode or photonic mixer. Such a THz source is expected to have a relatively high efficiency compared with conventional sources based on optical methods. The proposed THz source can find wide applications in THz science and technology, e.g., in THz imaging, THz sensors and detectors, THz communication systems, and THz optical integrated logic circuits.

  6. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

    Science.gov (United States)

    Neiva, Rodrigo F.; Gil, Luiz Fernando; Tovar, Nick; Janal, Malvin N.; Marao, Heloisa Fonseca; Pinto, Nelson; Coelho, Paulo G.

    2016-01-01

    Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL) were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1) dual acid-etched (DAE, micrometer scale textured) and (2) micrometer/nanometer scale textured (Ossean™ surface). L-PRF (Intraspin system, Intra-Lock International) was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α = 0.05) evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal), individually or in combination on bone area fraction occupancy (BAFO). Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants. PMID:28042577

  7. The Synergistic Effect of Leukocyte Platelet-Rich Fibrin and Micrometer/Nanometer Surface Texturing on Bone Healing around Immediately Placed Implants: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Rodrigo F. Neiva

    2016-01-01

    Full Text Available Aims. This study evaluated the effects of L-PRF presence and implant surface texture on bone healing around immediately placed implants. Methods. The first mandibular molars of 8 beagle dogs were bilaterally extracted, and implants (Blossom™, Intra-Lock International, Boca Raton, FL were placed in the mesial or distal extraction sockets in an interpolated fashion per animal. Two implant surfaces were distributed per sockets: (1 dual acid-etched (DAE, micrometer scale textured and (2 micrometer/nanometer scale textured (Ossean™ surface. L-PRF (Intraspin system, Intra-Lock International was placed in a split-mouth design to fill the macrogap between implant and socket walls on one side of the mandible. The contralateral side received implants without L-PRF. A mixed-model ANOVA (at α=0.05 evaluated the effect of implant surface, presence of L-PRF, and socket position (mesial or distal, individually or in combination on bone area fraction occupancy (BAFO. Results. BAFO values were significantly higher for the Ossean relative to the DAE surface on the larger mesial socket. The presence of L-PRF resulted in higher BAFO. The Ossean surface and L-PRF presence resulted in significantly higher BAFO. Conclusion. L-PRF and the micro-/nanometer scale textured surface resulted in increased bone formation around immediately placed implants.

  8. Grade Expectations: Rationality and Overconfidence

    Science.gov (United States)

    Magnus, Jan R.; Peresetsky, Anatoly A.

    2018-01-01

    Confidence and overconfidence are essential aspects of human nature, but measuring (over)confidence is not easy. Our approach is to consider students' forecasts of their exam grades. Part of a student's grade expectation is based on the student's previous academic achievements; what remains can be interpreted as (over)confidence. Our results are based on a sample of about 500 second-year undergraduate students enrolled in a statistics course in Moscow. The course contains three exams and each student produces a forecast for each of the three exams. Our models allow us to estimate overconfidence quantitatively. Using these models we find that students' expectations are not rational and that most students are overconfident, in agreement with the general literature. Less obvious is that overconfidence helps: given the same academic achievement students with larger confidence obtain higher exam grades. Female students are less overconfident than male students, their forecasts are more rational, and they are also faster learners in the sense that they adjust their expectations more rapidly. PMID:29375449

  9. Grade Expectations: Rationality and Overconfidence

    Directory of Open Access Journals (Sweden)

    Jan R. Magnus

    2018-01-01

    Full Text Available Confidence and overconfidence are essential aspects of human nature, but measuring (overconfidence is not easy. Our approach is to consider students' forecasts of their exam grades. Part of a student's grade expectation is based on the student's previous academic achievements; what remains can be interpreted as (overconfidence. Our results are based on a sample of about 500 second-year undergraduate students enrolled in a statistics course in Moscow. The course contains three exams and each student produces a forecast for each of the three exams. Our models allow us to estimate overconfidence quantitatively. Using these models we find that students' expectations are not rational and that most students are overconfident, in agreement with the general literature. Less obvious is that overconfidence helps: given the same academic achievement students with larger confidence obtain higher exam grades. Female students are less overconfident than male students, their forecasts are more rational, and they are also faster learners in the sense that they adjust their expectations more rapidly.

  10. Geant4-DNA track-structure simulations for gold nanoparticles: The importance of electron discrete models in nanometer volumes.

    Science.gov (United States)

    Sakata, Dousatsu; Kyriakou, Ioanna; Okada, Shogo; Tran, Hoang N; Lampe, Nathanael; Guatelli, Susanna; Bordage, Marie-Claude; Ivanchenko, Vladimir; Murakami, Koichi; Sasaki, Takashi; Emfietzoglou, Dimitris; Incerti, Sebastien

    2018-05-01

    Gold nanoparticles (GNPs) are known to enhance the absorbed dose in their vicinity following photon-based irradiation. To investigate the therapeutic effectiveness of GNPs, previous Monte Carlo simulation studies have explored GNP dose enhancement using mostly condensed-history models. However, in general, such models are suitable for macroscopic volumes and for electron energies above a few hundred electron volts. We have recently developed, for the Geant4-DNA extension of the Geant4 Monte Carlo simulation toolkit, discrete physics models for electron transport in gold which include the description of the full atomic de-excitation cascade. These models allow event-by-event simulation of electron tracks in gold down to 10 eV. The present work describes how such specialized physics models impact simulation-based studies on GNP-radioenhancement in a context of x-ray radiotherapy. The new discrete physics models are compared to the Geant4 Penelope and Livermore condensed-history models, which are being widely used for simulation-based NP radioenhancement studies. An ad hoc Geant4 simulation application has been developed to calculate the absorbed dose in liquid water around a GNP and its radioenhancement, caused by secondary particles emitted from the GNP itself, when irradiated with a monoenergetic electron beam. The effect of the new physics models is also quantified in the calculation of secondary particle spectra, when originating in the GNP and when exiting from it. The new physics models show similar backscattering coefficients with the existing Geant4 Livermore and Penelope models in large volumes for 100 keV incident electrons. However, in submicron sized volumes, only the discrete models describe the high backscattering that should still be present around GNPs at these length scales. Sizeable differences (mostly above a factor of 2) are also found in the radial distribution of absorbed dose and secondary particles between the new and the existing Geant4

  11. Simulation of Auger electron emission from nanometer-size gold targets using the Geant4 Monte Carlo simulation toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Incerti, S., E-mail: sebastien.incerti@tdt.edu.vn [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Univ. Bordeaux, CENBG, UMR 5797, F-33170 Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Suerfu, B.; Xu, J. [Department of Physics, Princeton University, Princeton, NJ (United States); Ivantchenko, V. [Ecoanalytica, Moscow (Russian Federation); Geant4 Associates International Ltd, Hebden Bridge (United Kingdom); Mantero, A. [SWHARD srl, via Greto di Cornigliano 6r, 16152 Genova (Italy); Brown, J.M.C. [School of Mathematics and Physics, Queen’s University Belfast, Belfast, Northern Ireland (United Kingdom); Bernal, M.A. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, SP (Brazil); Francis, Z. [Université Saint Joseph, Faculty of Sciences, Department of Physics, Beirut (Lebanon); Karamitros, M. [Notre Dame Radiation Laboratory, University of Notre Dame, Notre Dame, IN (United States); Tran, H.N. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam)

    2016-04-01

    A revised atomic deexcitation framework for the Geant4 general purpose Monte Carlo toolkit capable of simulating full Auger deexcitation cascades was implemented in June 2015 release (version 10.2 Beta). An overview of this refined framework and testing of its capabilities is presented for the irradiation of gold nanoparticles (NP) with keV photon and MeV proton beams. The resultant energy spectra of secondary particles created within and that escape the NP are analyzed and discussed. It is anticipated that this new functionality will improve and increase the use of Geant4 in the medical physics, radiobiology, nanomedicine research and other low energy physics fields.

  12. Device for the separation of spherically shaped fuel or breeding material particles for nuclear reactors

    International Nuclear Information System (INIS)

    Gyarmati, E.; Muenzer, R.

    1974-01-01

    Spherical fuel or blanket material particles are graded by diameter. The particles, which are present in a loose pebble bed, are singulized by means of a drum and by pneumatic suction. Next they pass through a drop section past an optical barrier which generates pulses corresponding to the number of particles. The particles then run through an eccentric wheel. This generates an electric voltage across a potentiometer which corresponds to the size of the particles. The slider of the potentiometer is connected with the axle of the eccentric wheel whose distance to the wall of the drop canal varies between the largest and the smallest possible diameters of the particles over half a revolution. Another barrier downstream of the eccentric wheel causes the particles to be graded in different containers in accordance with their diameters determined in this way. (DG) [de

  13. Measure of uncertainty in regional grade variability

    NARCIS (Netherlands)

    Tutmez, B.; Kaymak, U.; Melin, P.; Castillo, O.; Gomez Ramirez, E.; Kacprzyk, J.; Pedrycz, W.

    2007-01-01

    Because the geological events are neither homogeneous nor isotropic, the geological investigations are characterized by particularly high uncertainties. This paper presents a hybrid methodology for measuring of uncertainty in regional grade variability. In order to evaluate the fuzziness in grade

  14. Semiconductor Grade, Solar Silicon Purification Project. [photovoltaic solar energy conversion

    Science.gov (United States)

    Ingle, W. M.; Rosler, R. S.; Thompson, S. W.; Chaney, R. E.

    1979-01-01

    A low cost by-product, SiF4, is reacted with mg silicon to form SiF2 gas which is polymerized. The (SiF2)x polymer is heated forming volatile SixFy homologues which disproportionate on a silicon particle bed forming silicon and SiF4. The silicon analysis procedure relied heavily on mass spectroscopic and emission spectroscopic analysis. These analyses demonstrated that major purification had occured and some samples were indistinguishable from semiconductor grade silicon (except possibly for phosphorus). However, electrical analysis via crystal growth reveal that the product contains compensated phosphorus and boron.

  15. Interfaces in graded coatings on titanium-based implants

    OpenAIRE

    Lopez-Esteban, S.; Gutierrez-Gonzalez, C. F.; Gremillard, L.; Saiz, E.; Tomsia, A. P.

    2009-01-01

    Graded bilayered glass-ceramic composite coatings on Ti6Al4V substrates were fabricated using an enameling technique. The layers consisted of a mixture of glasses in the CaO-MgO-Na2O-K2O-P2O5 system with different amounts of calcium phosphates (CPs). Optimum firing conditions have been determined for the fabrication of coatings having good adhesion to the metal, while avoiding deleterious reactions between the glass and the ceramic particles. The final coatings do not crack or delaminate. The...

  16. The grading management of the quality assurance

    International Nuclear Information System (INIS)

    Ma Xiaozheng; Han Shufang; Yu Bei; Tian Xuehang

    2009-01-01

    This paper introduces the quality assurance grading management of the items, services and technology process on nuclear power plants (nuclear island, conventional island, BOP), such as the requirements and aim in the related code, guide, technical document, the requirements for the related units, the grading principle and grading, the considering method for the differences of QA requirements of the each QA grand, as well as the status and propositions in the QA grading management in China. (authors)

  17. The pathologist's mean grade is constant and individualizes the prognostic value of bladder cancer grading.

    Science.gov (United States)

    van Rhijn, Bas W G; van Leenders, Geert J L H; Ooms, Bert C M; Kirkels, Wim J; Zlotta, Alexandre R; Boevé, Egbert R; Jöbsis, Adriaan C; van der Kwast, Theo H

    2010-06-01

    A new grading system for bladder cancer (BCa) was adopted in 2004 to reduce observer variability and provide better prognostic information. We compared the World Health Organization (WHO) 1973 and 2004 systems for observer variability and prognosis. Slides of 173 primary non-muscle-invasive BCa were reviewed two times by four pathologists. Intra- and interobserver variability were assessed using κ statistics. We determined the mean grade (eg, G1/low malignant potential is 1 grade point, G2/low grade is 2 grade points) of the pathologists per grading cycle. Kaplan-Meier analyses were applied for prediction of recurrence and progression. For WHO 2004 and 1973 grading, the agreement between the pathologists was 39-74% (κ: 0.14-0.58) and 39-64% (κ: 0.15-0.41), respectively. The intraobserver agreement varied from 71% to 88% (κ: 0.55-0.81). The mean grade of a pathologist was constant (difference below 0.1 grade point) irrespective of the grading system. Conversely, mean-grade differences among the pathologists were high, up to 0.7 grade point. The mean grades for the WHO 2004 system were 0.3-0.5 grade point higher than those of WHO 1973. Mean grade distinguished low and high graders among the pathologists and was strongly linked with risk of progression in each grade category. The variation in mean grade among individual pathologists exceeded the grade shift caused by WHO 2004 grading. Knowledge of the pathologist's mean grade allows a better assessment of the prognostic value of grading. Mean grade has the potential to become a tool for quality assurance in pathology. Copyright © 2009 European Association of Urology. Published by Elsevier B.V. All rights reserved.

  18. Accelerators of atomic particles

    International Nuclear Information System (INIS)

    Sarancev, V.

    1975-01-01

    A brief survey is presented of accelerators and methods of accelerating elementary particles. The principle of collective accelerating of elementary particles is clarified and the problems are discussed of its realization. (B.S.)

  19. Elementary particles and cosmology

    International Nuclear Information System (INIS)

    Audouze, J.; Paty, M.

    2000-01-01

    The universe is the most efficient laboratory of particle physics and the understanding of cosmological processes implies the knowledge of how elementary particles interact. This article recalls the mutual influences between on the one hand: astrophysics and cosmology and on the other hand: nuclear physics and particle physics. The big-bang theory relies on nuclear physics to explain the successive stages of nucleo-synthesis and the study of solar neutrinos has led to discover new aspects of this particle: it is likely that neutrinos undergo oscillations from one neutrino type to another. In some universe events such as the bursting of a super-nova, particles are released with a kinetic energy that would be impossible to reach on earth with a particle accelerator. These events are become common points of interest between astrophysicists and particle physicists and have promoted a deeper cooperation between astrophysics and elementary particle physics. (A.C.)

  20. Particle Physics Education Sites

    Science.gov (United States)

    back to home page Particle Physics Education Sites quick reference Education and Information - National Laboratory Education Programs - Women and Minorities in Physics - Other Physics Sites - Physics Alliance - Accelerators at National Laboratories icon Particle Physics Education and Information sites: top

  1. Examining Text Complexity in the Early Grades

    Science.gov (United States)

    Fitzgerald, Jill; Elmore, Jeff; Hiebert, Elfrieda H.; Koons, Heather H.; Bowen, Kimberly; Sanford-Moore, Eleanor E.; Stenner, A. Jackson

    2016-01-01

    The Common Core raises the stature of texts to new heights, creating a hubbub. The fuss is especially messy at the early grades, where children are expected to read more complex texts than in the past. But early-grades teachers have been given little actionable guidance about text complexity. The authors recently examined early-grades texts to…

  2. Registration Patterns Under Two Different Grading Systems.

    Science.gov (United States)

    Remley, Audrey W.

    In the early 1960's, Westminster College adopted a new grading system, with the traditional grade levels of A, B, C, D, and F converted to DN (Distinction), HP (High Pass), P (Pass), and NC (No Credit). NC replaced both D and F of the old system, and grade point averages were abolished, in an effort to encourage students to register in more…

  3. Forecasting and recruitment in graded manpower systems

    NARCIS (Netherlands)

    van Nunen, J.A.E.E.; Wessels, J.

    1977-01-01

    In this paper a generalized Markov model is introduced to describe the dynamic behaviour of an individual employee in a graded Manpower system. Characteristics like the employee's grade, his educational level, his age and the time spent in his actual grade, can be incorporated in the Markov model.

  4. Demystify Learning Expectations to Address Grade Inflation

    Science.gov (United States)

    Hodges, Linda C.

    2014-01-01

    This article describes the subject of "grade inflation," a reference to educators giving higher grades to student work than their expectations for student achievement warrant. Of the many reasons why this practice happens, Hodges specifically discusses inflating grades as "a natural consequence" when the faculty really…

  5. Grade Inflation: An Issue for Higher Education?

    Science.gov (United States)

    Caruth, Donald L.; Caruth, Gail D.

    2013-01-01

    Grade inflation impacts university credibility, student courses of study, choices of institution, and other areas. There has been an upward shift in grades without a corresponding upward shift in knowledge gained. Some of the most frequently mentioned causes of grade inflation are: (1) student evaluations of professors; (2) student teacher…

  6. Does Education Corrupt? Theories of Grade Inflation

    Science.gov (United States)

    Oleinik, Anton

    2009-01-01

    Several theories of grade inflation are discussed in this review article. It is argued that grade inflation results from the substitution of criteria specific to the search for truth by criteria of quality control generated outside of academia. Particular mechanisms of the grade inflation that occurs when a university is transformed into a…

  7. Evaluation by discrete element method (DEM) of gap-graded packing potentialities for green concrete design

    NARCIS (Netherlands)

    Stroeven, P.; Le, L.B.N.

    2013-01-01

    Partial replacement of Portland cement by pozzolanic mineral admixtures exerts direct positive effects on CO2 emissions. The green character is reinforced by making use of incinerated vegetable waste, such as rice husk ash (RHA). Gap-grading leads to improved particle packing density with RHA as the

  8. 76 FR 80278 - Revision of Cotton Classification Procedures for Determining Cotton Leaf Grade

    Science.gov (United States)

    2011-12-23

    ... challenge to the provisions of this rule. Regulatory Flexibility Act Pursuant to requirements set forth in... currently part of the official USDA cotton classification. Accurate assignment of leaf grade is of economic... cost factor associated with its removal. Furthermore, since small leaf particles cannot always be...

  9. Review of particle properties

    Energy Technology Data Exchange (ETDEWEB)

    Yost, G P; Barnett, R M; Hinchliffe, I; Lynch, G R; Rittenberg, A; Ross, R R; Suzuki, M; Trippe, T G; Wohl, C G; Armstrong, B

    1988-04-14

    This review of the properties of gauge bosons, leptons, mesons, and baryons is an updating of the Review of Particle Properties, Particle Data Group (Phys. Lett. 170B (1986)). Data are evaluated, listed, averaged, and summarized in tables. We continue the more orderly set of particle names implemented in the 1986 edition. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available.

  10. Beyond the God particle

    CERN Document Server

    Lederman, Leon M

    2013-01-01

    On July 4, 2012, the long-sought Higgs Boson--aka "the God Particle"--was discovered at the world's largest particle accelerator, the LHC, in Geneva, Switzerland. On March 14, 2013, physicists at CERN confirmed it. This elusive subatomic particle forms a field that permeates the entire universe, creating the masses of the elementary particles that are the basic building blocks of everything in the known world--from viruses to elephants, from atoms to quasars.

  11. Magnetic assembly of nonmagnetic particles into photonic crystal structures.

    Science.gov (United States)

    He, Le; Hu, Yongxing; Kim, Hyoki; Ge, Jianping; Kwon, Sunghoon; Yin, Yadong

    2010-11-10

    We report the rapid formation of photonic crystal structures by assembly of uniform nonmagnetic colloidal particles in ferrofluids using external magnetic fields. Magnetic manipulation of nonmagnetic particles with size down to a few hundred nanometers, suitable building blocks for producing photonic crystals with band gaps located in the visible regime, has been difficult due to their weak magnetic dipole moment. Increasing the dipole moment of magnetic holes has been limited by the instability of ferrofluids toward aggregation at high concentration or under strong magnetic field. By taking advantage of the superior stability of highly surface-charged magnetite nanocrystal-based ferrofluids, in this paper we have been able to successfully assemble 185 nm nonmagnetic polymer beads into photonic crystal structures, from 1D chains to 3D assemblies as determined by the interplay of magnetic dipole force and packing force. In a strong magnetic field with large field gradient, 3D photonic crystals with high reflectance (83%) in the visible range can be rapidly produced within several minutes, making this general strategy promising for fast creation of large-area photonic crystals using nonmagnetic particles as building blocks.

  12. Characterization of Inherent Particles and Mechanism of Thermal Stress Induced Particle Formation in HSV-2 Viral Vaccine Candidate.

    Science.gov (United States)

    Li, Lillian; Kirkitadze, Marina; Bhandal, Kamaljit; Roque, Cristopher; Yang, Eric; Carpick, Bruce; Rahman, Nausheen

    2017-11-10

    Vaccine formulations may contain visible and/or subvisible particles, which can vary in both size and morphology. Extrinsic particles, which are particles not part of the product such as foreign contaminants, are generally considered undesirable and should be eliminated or controlled in injectable products. However, biological products, in particular vaccines, may also contain particles that are inherent to the product. Here we focus on the characterization of visible and subvisible particles in a live, replication-deficient viral vaccine candidate against HSV genital herpes in an early developmental stage. HSV-2 viral vaccine was characterized using a panel of analytical methods, including Fourier transform infrared spectroscopy (FTIR), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, liquid chromatography-mass spectrometry (LC-MS), light microscopy, transmission electron microscopy (TEM), micro-flow imaging (MFI), dynamic light scattering (DLS), right angle light scattering (RALS), and intrinsic fluorescence. Particles in HSV-2 vaccine typically ranged from hundreds of nanometers to hundreds of micrometers in size and were determined to be inherent to the product. The infectious titer did not correlate with any trend in subvisible particle concentration and size distribution as shown by DLS, MFI, and TEM under stressed conditions. This suggested that particle changes in the submicron range were related to HSV-2 virion structure and had direct impact on biological activity. It was also observed that subvisible and visible particles could induce aggregation in the viral product. The temperature induced aggregation was observed by RALS, intrinsic fluorescence, and DLS. The increase of subvisible particle size with temperature could be fitted to a two-step thermokinetic model. Visible and subvisible particles were found to be inherent to the HSV-2 viral vaccine product. The mechanism of protein aggregation was discussed and a two

  13. Empirical Research of College Students' Alternative Frameworks of Particle Mechanics

    Science.gov (United States)

    Wang, Hongmei

    2010-01-01

    Based on the constructive theory, about 300 college students of grade 05 of the electronic information specialty of Dezhou University are surveyed for their alternative frameworks of particle mechanics in college physics in this article. In the survey, the questionnaires are used to find out college students' alternative frameworks, and the…

  14. Ductility in hot isostatically pressed 250-grade maraging steel

    International Nuclear Information System (INIS)

    German, R.M.; Smugeresky, J.E.

    1978-01-01

    Prealloyed 250-grade maraging steel powder produced by the rotating electrode process was fully consolidated by hot isostatic pressing (HIP) at 1100 and 1200 0 C. The strength following aging (3 h at 480 0 C) equalled that of wrought material; however, ductility was negligible. This lack of ductility in the powder metallurgy product was traced to titanium segregation which occurred at the powder surface during power production. The formation of a titanium intermetallic at the prior particle boundaries during aging caused failure at low plastic strains. Altered aging treatments successfully broke up the embrittling film and resulted in a significant ductility recovery for the HIP material. Analysis of the fracture process indicates that further ductility gains are possible by reducing the titanium content, refining the particle size, and optimizing the thermal cycles

  15. Particle physics and cosmology

    International Nuclear Information System (INIS)

    Schramm, D.N.; Turner, M.S.

    1982-06-01

    work is described in these areas: cosmological baryon production; cosmological production of free quarks and other exotic particle species; the quark-hadron transition in the early universe; astrophysical and cosmological constraints on particle properties; massive neutrinos; phase transitions in the early universe; and astrophysical implications of an axion-like particle

  16. Particle-nuclear intersections

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    With the traditional distinctions between particle and nuclear physics becoming increasing blurred, the Fifth Conference on the Intersections of Particle and Nuclear Physics, held from May 31 to June 6 in St. Petersburg, Florida, brought together particle and nuclear physicists to discuss common research efforts and to define and plan a united approach

  17. Review of particle properties

    International Nuclear Information System (INIS)

    Trippe, T.G.; Barbaro-Galtieri, A.; Kelly, R.L.; Rittenberg, A.; Rosenfeld, A.H.; Yost, G.P.; Barash-Schmidt, N.; Bricman, C.; Hemingway, R.J.; Losty, M.J.; Roos, M.; Chaloupka, V.; Armstrong, B.

    1976-01-01

    This review of the properties of leptons, mesons, and baryons is an updating of Review of Particle Properties, Particle Data Group [Phys. Letters 50B, No.1 (1974), and Supplement, Rev. Mod. Phys. 47 (1975) 535]. Data are evaluated, listed, averaged, and summarized in tables. Numerous tables, figures, and formulae of interest to particle physicists are also included. A data booklet is available

  18. Atomic Particle Detection

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Hal

    1970-01-01

    This booklet tells how scientists observe the particles and electromagnetic radiation that emerges from an atomic nucleus. The equipment used falls into two general categories: counters which count each particle as it passes by, and track detectors, which make a photographic record of the particle's track.

  19. Study of particle swarm optimization particle trajectories

    CSIR Research Space (South Africa)

    Van den Bergh, F

    2006-01-01

    Full Text Available . These theoretical studies concentrate mainly on simplified PSO systems. This paper overviews current theoretical studies, and extend these studies to investigate particle trajectories for general swarms to include the influence of the inertia term. The paper also...

  20. The Relationship of Grade Span in 9th Grade to Math Achievement in High School

    Science.gov (United States)

    West, John; Miller, Mary Lou; Myers, Jim; Norton, Timothy

    2015-01-01

    Purpose, Scope, and Method of Study: The purpose of this study was to determine if a correlation exists between grade span for ninth grade and gains in math achievement test scores in 10th grade and 12th grade. A quantitative, longitudinal, correlational research design was employed to investigate the research questions. The population was high…

  1. High grade glioma: Imaging combined with pathological grade defines management and predicts prognosis

    International Nuclear Information System (INIS)

    Burnet, Neil G.; Lynch, Andrew G.; Jefferies, Sarah J.; Price, Stephen J.; Jones, Phil H.; Antoun, Nagui M.; Xuereb, John H.; Pohl, Ute

    2007-01-01

    Introduction: There is ambiguity in pathological grading of high grade gliomas within the WHO 2000 classification, especially those with predominant oligodendroglial differentiation. Patients and methods: All adult high grade gliomas treated radically, 1996-2005, were assessed. Cases in which pathology was grade III but radiology suggested glioblastoma (GBM) were classified as 'grade III/IV'; their pathology was reviewed. Results: Data from 245 patients (52 grade III, 18 grade III/IV, 175 GBM) were analysed using a Cox Proportional Hazards model. On pathology review, features suggestive of more aggressive behaviour were found in all 18 grade III/IV tumours. Oligodendroglial components with both necrosis and microvascular proliferation were present in 7. MIB-1 counts for the last 8 were all above 14%, mean 27%. Median survivals were: grade III 34 months, grade III/IV 10 months, GBM 11 months. Survival was not significantly different between grade III/IV and GBM. Patients with grade III/IV tumours had significantly worse outcome than grade III, with a hazard of death 3.7 times higher. Conclusions: The results highlight the current inconsistency in pathological grading of high grade tumours, especially those with oligodendroglial elements. Patients with histological grade III tumours but radiological appearances suggestive of GBM should be managed as glioblastoma

  2. Association of Grade Configuration with School Climate for 7th and 8th Grade Students

    Science.gov (United States)

    Malone, Marisa; Cornell, Dewey; Shukla, Kathan

    2017-01-01

    Educational authorities have questioned whether middle schools provide the best school climate for 7th and 8th grade students, and proposed that other grade configurations such as K-8th grade schools may provide a better learning environment. The purpose of this study was to compare 7th and 8th grade students' perceptions of 4 key features of…

  3. Comparing Dropout Predictors for Two State-Level Panels Using Grade 6 and Grade 8 Data

    Science.gov (United States)

    Franklin, Bobby J.; Trouard, Stephen B.

    2016-01-01

    The purpose of this study was to examine the effectiveness of dropout predictors across time. Two state-level high school graduation panels were selected to begin with the seventh and ninth grades but end at the same time. The first panel (seventh grade) contained 29,554 students and used sixth grade predictors. The second panel (ninth grade)…

  4. Grade Inflation Marches On: Grade Increases from the 1990s to 2000s

    Science.gov (United States)

    Kostal, Jack W.; Kuncel, Nathan R.; Sackett, Paul R.

    2016-01-01

    Grade inflation threatens the integrity of college grades as indicators of academic achievement. In this study, we contribute to the literature on grade inflation by providing the first estimate of the size of grade increases at the student level between the mid-1990s and mid-2000s. By controlling for student characteristics and course-taking…

  5. The effect of various grading scales on student grade point averages.

    Science.gov (United States)

    Barnes, Kelli D; Buring, Shauna M

    2012-04-10

    To investigate changes in and the impact of grading scales from 2005 to 2010 and explore pharmacy faculty and student perceptions of whole-letter and plus/minus grading scales on cumulative grade point averages (GPAs) in required courses. Grading scales used in 2010 at the University of Cincinnati College of Pharmacy were retrospectively identified and compared to those used in 2005. Mean GPA was calculated using a whole-letter grading scale and a plus/minus grading scale to determine the impact of scales on GPA. Faculty members and students were surveyed regarding their perceptions of plus/minus grading. Nine unique grading scales were used throughout the curriculum, including plus/minus (64%) and whole-letter (21%) grading scales. From 2005 to 2010 there was transition from use of predominantly whole-letter scales to plus/minus grading scales. The type of grading scale used did not affect the mean cumulative GPA. Students preferred use of a plus-only grading scale while faculty members preferred use of a plus/minus grading scale. The transition from whole-letter grading to plus/minus grading in courses from 2005 to 2010 reflects pharmacy faculty members' perception that plus/minus grading allows for better differentiation between students' performances.

  6. Light scattering by cosmic particles

    NARCIS (Netherlands)

    Hovenier, J.W.; Min, M.

    2008-01-01

    We define cosmic particles as particles outside the Earth. Two types of cosmic particles can be distinguished, namely liquid and solid particles. The solid particles are often called grains or cosmic dust particles. Cosmic particles occur in a great variety of astronomical objects and environments.

  7. Slowing of charged particles by particle methods

    International Nuclear Information System (INIS)

    Mercier, B.

    1985-03-01

    We review some facts about particle methods for solving linear hyperbolic equations. We show how one gets an evaluation of integral quantities like: ∫ u(x,t) zeta(x,t) dxdt where u denotes the solution and zeta an arbitrary weight function. Then, we apply the method to the equation describing charged particle transport in a plasma with emphasis on the evaluation of energy deposition on ions and electrons [fr

  8. Objective-lens-free Fiber-based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System.

    Science.gov (United States)

    Ti, Chaoyang; Ho-Thanh, Minh-Tri; Wen, Qi; Liu, Yuxiang

    2017-10-13

    Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

  9. Characterization of Surface-Enhanced Raman Scattering of Nicotine Utilizing Plasmonic Nanometals for the Applications of Medical and Chemical Sensing

    Science.gov (United States)

    Jackson, Ashley; Rigo, Maria; Seo, Jaetae; HU Team

    2011-05-01

    Raman spectroscopy has received a great deal of interest for its applications in biological sensing and cell imaging due to the ease with which it can be used to extract significant data from tissue and cells. This study has focused on the application of SERS for nicotine detection. Liquid nicotine was diluted and combined with Au nanoparticles (NPs). The nicotine-gold solution was analyzed by acquiring Raman spectra data using a Delta Nu Spectrometer. Absorption data shows the characteristic peak of Au NPs at ~528 nm while showing successful aggregation of the nicotine particles. Data taken from Raman spectra shows characteristic Raman shifts of nicotine at ~1030 cm-1 and ~1590 cm-1. Currently work is being done to optimize the SERS signal for nicotine in the 1590-1600 region using higher concentrations of nicotine and various sizes of Au NPs. This work at Hampton University was supported by the National Science Foundation (HRD-0734635 and HRD-063037).

  10. Elementary particles. 2

    International Nuclear Information System (INIS)

    Ranft, G.; Ranft, J.

    1977-01-01

    In this part the subject is covered under the following headings, methods for producing high-energy particles; interaction of high-energy particles with matter; methods for the detection of high-energy particles; symmetry properties and conservation laws; quantum number and selection rules; theorem of scattering behaviour at asymptotically high energies; statistical methods in elementary particle physics; interaction of high-energy particles with nuclei; relations of high-energy physics to other branches of science and its response to engineering. Intended as information on high-energy physics for graduate students and research workers familiar with the fundamentals of classical and quantum physics

  11. Review of particle properties

    International Nuclear Information System (INIS)

    Montanet, L.; Gieselmann, K. Technical Associate; Barnett, R.M.; Groom, D.E.; Trippe, T.G.; Wohl, C.G.; Armstrong, B. Technical Associate; Wagman, G.S. Technical Associate; Murayama, H.; Stone, J.; Hernandez, J.J.; Porter, F.C.; Morrison, R.J.; Manohar, A.; Aguilar-Benitez, M.; Caso, C.; Lantero, P. Technical Associate; Crawford, R.L.; Roos, M.; Toernqvist, N.A.; Hayes, K.G.; Hoehler, G.

    1994-01-01

    This biennial review summarizes much of Particle Physics. Using data from previous editions, plus 2300 new measurements from 700 papers, we list evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, monopoles, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review

  12. Kinetics of small particle activation in supersaturated vapors

    Energy Technology Data Exchange (ETDEWEB)

    McGraw, R.; Wang, J.

    2010-08-29

    We examine the nucleated (with barrier) activation of perfectly wetting (zero contact angle) particles ranging from bulk size down to one nanometer. Thermodynamic properties of the particles, coated with liquid layers of varying thickness and surrounded by vapor, are analyzed. Nano-size particles are predicted to activate at relative humidity below the Kelvin curve on crossing a nucleation barrier, located at a critical liquid layer thickness such that the total particle size (core + liquid layer) equals the Kelvin radius (Fig. 1). This barrier vanishes precisely as the critical layer thickness approaches the thin layer limit and the Kelvin radius equals the radius of the particle itself. These considerations are similar to those included in Fletcher's theory (Fletcher, 1958) however the present analysis differs in several important respects. Firstly, where Fletcher used the classical prefactor-exponent form for the nucleation rate, requiring separate estimation of the kinetic prefactor, we solve a diffusion-drift equation that is equivalent to including the full Becker-Doering (BD) multi-state kinetics of condensation/evaporation along the growth coordinate. We also determine the mean first passage time (MFPT) for barrier crossing (Wedekind et al., 2007), which is shown to provide a generalization of BD nucleation kinetics especially useful for barrier heights that are considerably lower than those typically encountered in homogeneous vapor-liquid nucleation, and make explicit comparisons between the MFPT and BD kinetic models. Barrier heights for heterogeneous nucleation are computed by a thermo-dynamic area construction introduced recently to model deliquescence and efflorescence of small particles (McGraw and Lewis, 2009). In addition to providing a graphical representation of the activation process that offers new insights, the area construction provides a molecular approach that avoids explicit use of the interfacial tension. Typical barrier profiles for

  13. Fluidization of spherocylindrical particles

    Science.gov (United States)

    Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.

    2017-06-01

    Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.

  14. A graded nano-TiN coating on biomedical Ti alloy: Low friction coefficient, good bonding and biocompatibility.

    Science.gov (United States)

    Cui, Wenfang; Qin, Gaowu; Duan, Jingzhu; Wang, Huan

    2017-02-01

    In order to solve wear resistance of Ti alloy biomaterials, the concept of a graded nano-TiN coating has been proposed. The coating was prepared on Ti-6Al-4V bio-alloy by DC reactive magnetron sputtering. The wear performance of the coated specimens was measured in Hank's solution under the load of 10N, and the biocompatibility was evaluated according to ISO-10993-4 standard. The results show that the gradient coating exhibits a gradual change in compositions and microstructures along the direction of film growth. Nano-TiN with the size of several to dozens nanometers and Ti 4 N 3-x transitional phase with variable composition form a graded composite structure, which significantly improves adhesion strength (L c1 =80N, L c2 =120N), hardness (21GPa) and anti-wear performance (6.2×10 -7 mm 3 /Nm). The excellent bonding and wear resistance result from a good match of mechanical properties at substrate/coating interface and the strengthening and toughening effects of the nanocrystalline composite. The nano-TiN coating has also been proved to have good biocompatibility through in-vitro cytotoxicity, hemocompatibility and general toxicity tests. And thus, the proposed graded nano-TiN coating is a good candidate improving wear resistance of many implant medical devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Monosodium titanate particle characterization

    International Nuclear Information System (INIS)

    Chandler, G.T.; Hobbs, D.T.

    1993-01-01

    A characterization study was performed on monosodium titanate (MST) particles to determine the effect of high shear forces expected from the In-Tank Precipitation (ITP) process pumps on the particle size distribution. The particles were characterized using particle size analysis and scanning electron microscopy (SEM). No significant changes in particle size distributions were observed between as-received MST and after 2--4 hours of shearing. Both as-received and sheared MST particles contained a large percentage of porosity with pore sizes on the order of 500 to 2,000 Angstroms. Because of the large percentage of porosity, the overall surface area of the MST is dominated by the internal surfaces. The uranium and plutonium species present in the waste solution will have access to both interior and exterior surfaces. Therefore, uranium and plutonium loading should not be a strong function of MST particle size

  16. Effect of flow characteristics on ultrafine particle emissions from range hoods.

    Science.gov (United States)

    Tseng, Li-Ching; Chen, Chih-Chieh

    2013-08-01

    In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods

  17. Low-cost, high-precision micro-lensed optical fiber providing deep-micrometer to deep-nanometer-level light focusing.

    Science.gov (United States)

    Wen, Sy-Bor; Sundaram, Vijay M; McBride, Daniel; Yang, Yu

    2016-04-15

    A new type of micro-lensed optical fiber through stacking appropriate high-refractive microspheres at designed locations with respect to the cleaved end of an optical fiber is numerically and experimentally demonstrated. This new type of micro-lensed optical fiber can be precisely constructed with low cost and high speed. Deep micrometer-scale and submicrometer-scale far-field light spots can be achieved when the optical fibers are multimode and single mode, respectively. By placing an appropriate teardrop dielectric nanoscale scatterer at the far-field spot of this new type of micro-lensed optical fiber, a deep-nanometer near-field spot can also be generated with high intensity and minimum joule heating, which is valuable in high-speed, high-resolution, and high-power nanoscale detection compared with traditional near-field optical fibers containing a significant portion of metallic material.

  18. Frontier of nanometer devices. Part 2. Trends in nanostructure fabrication technology. Nanometa debaisu kenkyu saizensen. 2. Nanometa bisai kako gijutsu no genjo to tenbo

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, S [NEC Corp., Tokyo (Japan)

    1994-06-20

    Nanometer fabrication technology shows a remarkable progress. Conventional electric beam enables 10 nm lithography and the scanning transmission electron microscopy (STEM) and the scanning tunneling microscopy (STM) enable fabrication below 10 nm even to the level of atom and molecule manipulation. This paper describes the recent trends in nanotechnology (nanolithography and nano dry etching) by the use of electron and ion beams. In the atom technology by the use of STM, studies are in progress on processing with atomic force, electric field evaporation and chemical reaction. Moreover, this paper describes recent development in nano natural lithography, self-formation lithography, atomic layer lithography and nanolithography using electron beam holography. The present state and future prospects are discussed. 31 refs., 10 figs., 1 tab.

  19. Imaging Live Cells at the Nanometer-Scale with Single-Molecule Microscopy: Obstacles and Achievements in Experiment Optimization for Microbiology

    Science.gov (United States)

    Haas, Beth L.; Matson, Jyl S.; DiRita, Victor J.; Biteen, Julie S.

    2015-01-01

    Single-molecule fluorescence microscopy enables biological investigations inside living cells to achieve millisecond- and nanometer-scale resolution. Although single-molecule-based methods are becoming increasingly accessible to non-experts, optimizing new single-molecule experiments can be challenging, in particular when super-resolution imaging and tracking are applied to live cells. In this review, we summarize common obstacles to live-cell single-molecule microscopy and describe the methods we have developed and applied to overcome these challenges in live bacteria. We examine the choice of fluorophore and labeling scheme, approaches to achieving single-molecule levels of fluorescence, considerations for maintaining cell viability, and strategies for detecting single-molecule signals in the presence of noise and sample drift. We also discuss methods for analyzing single-molecule trajectories and the challenges presented by the finite size of a bacterial cell and the curvature of the bacterial membrane. PMID:25123183

  20. Imaging Nanometer Phase Coexistence at Defects During the Insulator-Metal Phase Transformation in VO2 Thin Films by Resonant Soft X-ray Holography.

    Science.gov (United States)

    Vidas, Luciana; Günther, Christian M; Miller, Timothy A; Pfau, Bastian; Perez-Salinas, Daniel; Martínez, Elías; Schneider, Michael; Gührs, Erik; Gargiani, Pierluigi; Valvidares, Manuel; Marvel, Robert E; Hallman, Kent A; Haglund, Richard F; Eisebitt, Stefan; Wall, Simon

    2018-05-18

    We use resonant soft X-ray holography to image the insulator-metal phase transition in vanadium dioxide with element and polarization specificity and nanometer spatial resolution. We observe that nanoscale inhomogeneity in the film results in spatial-dependent transition pathways between the insulating and metallic states. Additional nanoscale phases form in the vicinity of defects which are not apparent in the initial or final states of the system, which would be missed in area-integrated X-ray absorption measurements. These intermediate phases are vital to understand the phase transition in VO 2 , and our results demonstrate how resonant imaging can be used to understand the electronic properties of phase-separated correlated materials obtained by X-ray absorption.

  1. Development of X-Y servo pneumatic-piezoelectric hybrid actuators for position control with high response, large stroke and nanometer accuracy.

    Science.gov (United States)

    Chiang, Mao-Hsiung

    2010-01-01

    This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

  2. Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy

    Directory of Open Access Journals (Sweden)

    Mao-Hsiung Chiang

    2010-03-01

    Full Text Available This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm and nanometer accuracy (20 nm. In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

  3. Nanometer-scale, quantitative composition mappings of InGaN layers from a combination of scanning transmission electron microscopy and energy dispersive x-ray spectroscopy

    International Nuclear Information System (INIS)

    Pantzas, K; Voss, P L; Ougazzaden, A; Patriarche, G; Largeau, L; Mauguin, O; Troadec, D; Gautier, S; Moudakir, T; Suresh, S

    2012-01-01

    Using elastic scattering theory we show that a small set of energy dispersive x-ray spectroscopy (EDX) measurements is sufficient to experimentally evaluate the scattering function of electrons in high-angle annular dark field scanning transmission microscopy (HAADF-STEM). We then demonstrate how to use this function to transform qualitative HAADF-STEM images of InGaN layers into precise, quantitative chemical maps of the indium composition. The maps obtained in this way combine the resolution of HAADF-STEM and the chemical precision of EDX. We illustrate the potential of such chemical maps by using them to investigate nanometer-scale fluctuations in the indium composition and their impact on the growth of epitaxial InGaN layers. (paper)

  4. Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO{sub 2} transformation

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, Ramasamy [Department of Chemistry, Thiagarajar College, Madurai, Tamilnadu 625 009 (India); National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India); Thamaraichelvan, Arunachalam [Faculty of Allied Health Sciences, Chettinad Hospital & Research Institute, Kelambakkam, Tamilnadu 603 103 (India); Ganesan, Tharumeya Kuppusamy [Department of Chemistry, The American College, Madurai, Tamilnadu 625 002 (India); Viswanathan, Balasubramanian, E-mail: bvnathan@iitm.ac.in [National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India)

    2017-02-28

    Highlights: • On interaction with adsorbate CO{sub 2,} the adsorbent changes its configuration around the metal. • Electron transfer is faster in low coordinative environment of Cu. • CO formation is more favorable on Cu sites with even coordination number. • Cu at coordination number two has a over potential of −0.35 V. - Abstract: Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO{sub 2} to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO{sub 2} to CO at an applied potential of −0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO{sub 2} to various value added chemicals.

  5. Characterization of nanometer-thick polycrystalline silicon with phonon-boundary scattering enhanced thermoelectric properties and its application in infrared sensors.

    Science.gov (United States)

    Zhou, Huchuan; Kropelnicki, Piotr; Lee, Chengkuo

    2015-01-14

    Although significantly reducing the thermal conductivity of silicon nanowires has been reported, it remains a challenge to integrate silicon nanowires with structure materials and electrodes in the complementary metal-oxide-semiconductor (CMOS) process. In this paper, we investigated the thermal conductivity of nanometer-thick polycrystalline silicon (poly-Si) theoretically and experimentally. By leveraging the phonon-boundary scattering, the thermal conductivity of 52 nm thick poly-Si was measured as low as around 12 W mK(-1) which is only about 10% of the value of bulk single crystalline silicon. The ZT of n-doped and p-doped 52 nm thick poly-Si was measured as 0.067 and 0.024, respectively, while most previously reported data had values of about 0.02 and 0.01 for a poly-Si layer with a thickness of 0.5 μm and above. Thermopile infrared sensors comprising 128 pairs of thermocouples made of either n-doped or p-doped nanometer-thick poly-Si strips in a series connected by an aluminium (Al) metal interconnect layer are fabricated using microelectromechanical system (MEMS) technology. The measured vacuum specific detectivity (D*) of the n-doped and p-doped thermopile infrared (IR) sensors are 3.00 × 10(8) and 1.83 × 10(8) cm Hz(1/2) W(-1) for sensors of 52 nm thick poly-Si, and 5.75 × 10(7) and 3.95 × 10(7) cm Hz(1/2) W(-1) for sensors of 300 nm thick poly-Si, respectively. The outstanding thermoelectric properties indicate our approach is promising for diverse applications using ultrathin poly-Si technology.

  6. SEM and EBSD characterization of bi-layered functionally graded hard metal composites; REM- und EBSD-Charakterisierung von zweischichtigen, funktionell abgestuften Metallverbundwerkstoffen

    Energy Technology Data Exchange (ETDEWEB)

    Prat, Orlando; Sanhueza, Felipe [Univ. de Concepcion (Chile). Dept. de Ingenieria de Materiales; Suarez, Sebastian [Saarland Univ., Saarbruecken (Germany). Chair of Functional Materials; Garcia, Jose [AB Sandvik Coromant R and D, Stockholm (Sweden)

    2016-11-15

    WC-Co bi-layer functionally graded composites were produced by powder metallurgy techniques. The influence of WC particle size and the grain growth inhibitor on the formation of the functionally graded composite was investigated. SEM images show that all sintered samples present a graded microstructure after sintering, with two side regions of extra-coarse and coarse WC-Co and a clear, dense interface without defects or other phases. EBSD results showed a change of WC particle size depending on the processing and the addition of Mo{sub 2}C. Cobalt binder distribution corresponds to WC particle size. Hardness values correlate to WC particle size and binder content. It is shown that tailored hardness/toughness can be produced by adjusting the WC particle size and binder content on both sides of the bi-layer composite.

  7. Effective modification of particle surface properties using ultrasonic water mist

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki

    2009-01-01

    The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades. The powdered particles were supplied...... properties. It was found that rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the level of fines with very slight...... increment in particle size. The changes in thiamine powder flow were mainly due to narrowing in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications. The aqueous mist application did not cause any alteration of the crystal structures...

  8. Permanent magnet system to guide superparamagnetic particles

    Science.gov (United States)

    Baun, Olga; Blümler, Peter

    2017-10-01

    A new concept of using permanent magnet systems for guiding superparamagnetic nano-particles on arbitrary trajectories over a large volume is proposed. The basic idea is to use one magnet system which provides a strong, homogeneous, dipolar magnetic field to magnetize and orient the particles, and a second constantly graded, quadrupolar field, superimposed on the first, to generate a force on the oriented particles. In this configuration the motion of the particles is driven predominantly by the component of the gradient field which is parallel to the direction of the homogeneous field. As a result, particles are guided with constant force and in a single direction over the entire volume. The direction is simply adjusted by varying the angle between quadrupole and dipole. Since a single gradient is impossible due to Gauß' law, the other gradient component of the quadrupole determines the angular deviation of the force. However, the latter can be neglected if the homogeneous field is stronger than the local contribution of the quadrupole field. A possible realization of this idea is a coaxial arrangement of two Halbach cylinders. A dipole to evenly magnetize and orient the particles, and a quadrupole to generate the force. The local force was calculated analytically for this particular geometry and the directional limits were analyzed and discussed. A simple prototype was constructed to demonstrate the principle in two dimensions on several nano-particles of different size, which were moved along a rough square by manual adjustment of the force angle. The observed velocities of superparamagnetic particles in this prototype were always several orders of magnitude higher than the theoretically expected value. This discrepancy is attributed to the observed formation of long particle chains as a result of their polarization by the homogeneous field. The magnetic moment of such a chain is then the combination of that of its constituents, while its hydrodynamic radius

  9. Gaining Control over Radiolytic Synthesis of Uniform Sub-3-nanometer Palladium Nanoparticles: Use of Aromatic Liquids in the Electron Microscope.

    Science.gov (United States)

    Abellan, Patricia; Parent, Lucas R; Al Hasan, Naila; Park, Chiwoo; Arslan, Ilke; Karim, Ayman M; Evans, James E; Browning, Nigel D

    2016-02-16

    Synthesizing nanomaterials of uniform shape and size is of critical importance to access and manipulate the novel structure-property relationships arising at the nanoscale, such as catalytic activity. In this work, we synthesize Pd nanoparticles with well-controlled size in the sub-3 nm range using scanning transmission electron microscopy (STEM) in combination with an in situ liquid stage. We use an aromatic hydrocarbon (toluene) as a solvent that is very resistant to high-energy electron irradiation, which creates a net reducing environment without the need for additives to scavenge oxidizing radicals. The primary reducing species is molecular hydrogen, which is a widely used reductant in the synthesis of supported metal catalysts. We propose a mechanism of particle formation based on the effect of tri-n-octylphosphine (TOP) on size stabilization, relatively low production of radicals, and autocatalytic reduction of Pd(II) compounds. We combine in situ STEM results with insights from in situ small-angle X-ray scattering (SAXS) from alcohol-based synthesis, having similar reduction potential, in a customized microfluidic device as well as ex situ bulk experiments. This has allowed us to develop a fundamental growth model for the synthesis of size-stabilized Pd nanoparticles and demonstrate the utility of correlating different in situ and ex situ characterization techniques to understand, and ultimately control, metal nanostructure synthesis.

  10. Study of the stability of the nanometer-sized oxides dispersed in ODS steels under ion irradiations

    International Nuclear Information System (INIS)

    Lescoat, M.-L.

    2012-01-01

    Oxide Dispersion Strengthened (ODS) Ferritic-Martensitic (FM) alloys are expected to play an important role as cladding materials in Generation IV sodium fast reactors operating in extreme temperature (400-500 C) and irradiation conditions (up to 200 dpa). Since nano-oxides give ODS steels their high temperature strength, the stability of these particles is an important issue. The present study evaluates the radiation response of nano-oxides by the use of in-situ and ex-situ ion irradiations performed on both Fe18Cr1W0,4Ti +0,3 Y 2 O 3 and Fe18Cr1W0,4Ti + 0.3 MgO ODS steels. In particular, the results showed that Y-Ti-O nano-oxides are quite stable under very high irradiation dose, namely 219 dpa at 500 C, and that the oxide interfacial structures are likely playing an important role on the behavior under irradiation (oxide stability and point defect recombination. (author) [fr

  11. Preparation of ZnO/SnO2 Composite Nanometer Photocatalyst and Photocatalytic Treatment of Marine Diesel Pollution

    Science.gov (United States)

    Zhang, J.; Yu, X. C.; Nie, Z. W.; Guo, M. C.; Liu, J. H.; Wang, L. P.

    2017-12-01

    The ZnO/SnO2 composite nanophotocatalyst studied in this paper was prepared by a chemical precipitation method, which were characterized by XRD and SEM. The results show that the prepared samples were rutile SnO2 particles and the average grain size is 8.41 nm. In this paper, the factors for the degradation efficiency of marine diesel oil degraded by ZnO/SnO2 composite nanophotocatalyst are the catalysts’ doping ratio, the initial concentration of oil, the pH value of seawater, the dosage of catalyst and the dosage of hydrogen peroxide. The results show that the ZnO/SnO2 composite nanophotocatalyst can effectively degrade seawater diesel oil under UV light. When the doping ratio of ZnO and SnO2 is 0.35, the reaction time is 2.5 hours, the pH value of seawater with oil is 7, The concentration of diesel oil is 0.1g/L, the dosage of catalyst is 0.3g/L and the dosage of hydrogen peroxide is 0.1 g/L, the highest degradation rate is 91.54%.

  12. Lecture II. Charmed particle spectroscopy

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    The discussion of charmed particle spectroscopy covers the particle properties and interrelations from a charmed quark composition point of view including SU(4)-symmetry generalities, mesons, baryons, charmed particle masses, and decays of charmed particles. 6 references

  13. Is the Sky Falling? Grade Inflation and the Signaling Power of Grades.

    Science.gov (United States)

    Pattison, Evangeleen; Grodsky, Eric; Muller, Chandra

    2013-06-01

    Grades are the fundamental currency of our educational system; they signal academic achievement and non-cognitive skills to parents, employers, postsecondary gatekeepers, and students themselves. Grade inflation compromises the signaling value of grades, undermining their capacity to achieve the functions for which they are intended. We challenge the 'increases in grade point average' definition of grade inflation and argue that grade inflation must be understood in terms of the signaling power of grades. Analyzing data from four nationally representative samples, we find that in the decades following 1972: (a) grades have risen at high schools and dropped at four-year colleges, in general, and selective four-year institutions, in particular; and (b) the signaling power of grades has attenuated little, if at all.

  14. Particle segregation in pneumatic conveying lines

    Energy Technology Data Exchange (ETDEWEB)

    McGlinchey, D.; Marjanovic, P.; Cook, S.; Jones, M.G. [Glasgow Caledonian University, Glasgow (United Kingdom). Centre for Industrial Bulk Solids Handling

    2000-07-01

    This investigation studied segregation of particles during pneumatic transport from a theoretical and experimental perspective. Dilute phase or suspension flow and dense phase (non-suspension flow) were both considered. A computer model was generated based on the conservation equations to investigate dilute phase conditions; an initial qualitative investigation of material behaviour being conveyed in dense phase was made with plastic pellets and salt as a segregating mixture in a small test rig and the results from a full scale test rig conveying two grades of coal of different size distributions are discussed. 11 refs., 9 figs., 1 tab.

  15. Methods for forming particles

    Science.gov (United States)

    Fox, Robert V.; Zhang, Fengyan; Rodriguez, Rene G.; Pak, Joshua J.; Sun, Chivin

    2016-06-21

    Single source precursors or pre-copolymers of single source precursors are subjected to microwave radiation to form particles of a I-III-VI.sub.2 material. Such particles may be formed in a wurtzite phase and may be converted to a chalcopyrite phase by, for example, exposure to heat. The particles in the wurtzite phase may have a substantially hexagonal shape that enables stacking into ordered layers. The particles in the wurtzite phase may be mixed with particles in the chalcopyrite phase (i.e., chalcopyrite nanoparticles) that may fill voids within the ordered layers of the particles in the wurtzite phase thus produce films with good coverage. In some embodiments, the methods are used to form layers of semiconductor materials comprising a I-III-VI.sub.2 material. Devices such as, for example, thin-film solar cells may be fabricated using such methods.

  16. LHCb unveils new particles

    CERN Multimedia

    Stefania Pandolfi

    2016-01-01

    The LHCb collaboration announces the observation of four “exotic” particles from its analysis of the LHC data.   The LHCb experimental cavern. On 28 June, the LHCb collaboration reported the observation of three new "exotic" particles and confirmation of the existence of a fourth one in data from the LHC. These particles each appear to be formed by four quarks (the fundamental constituents of the matter inside all the atoms of the universe): two quarks and two antiquarks (that is, a tetraquark). Due to their non-standard quark content, the newly observed particles have been included in the broad category of so-called exotic particles, although their exact theoretical interpretation is still under study.            The quark model, proposed by Murray Gell-Mann and George Zweig in 1964, is considered to be the most valid scheme for the classification of hadrons (all the composite particles) that has been fou...

  17. Particle Swarm Optimization

    Science.gov (United States)

    Venter, Gerhard; Sobieszczanski-Sobieski Jaroslaw

    2002-01-01

    The purpose of this paper is to show how the search algorithm known as particle swarm optimization performs. Here, particle swarm optimization is applied to structural design problems, but the method has a much wider range of possible applications. The paper's new contributions are improvements to the particle swarm optimization algorithm and conclusions and recommendations as to the utility of the algorithm, Results of numerical experiments for both continuous and discrete applications are presented in the paper. The results indicate that the particle swarm optimization algorithm does locate the constrained minimum design in continuous applications with very good precision, albeit at a much higher computational cost than that of a typical gradient based optimizer. However, the true potential of particle swarm optimization is primarily in applications with discrete and/or discontinuous functions and variables. Additionally, particle swarm optimization has the potential of efficient computation with very large numbers of concurrently operating processors.

  18. Production of Food Grade Yeasts

    Directory of Open Access Journals (Sweden)

    Argyro Bekatorou

    2006-01-01

    Full Text Available Yeasts have been known to humans for thousands of years as they have been used in traditional fermentation processes like wine, beer and bread making. Today, yeasts are also used as alternative sources of high nutritional value proteins, enzymes and vitamins, and have numerous applications in the health food industry as food additives, conditioners and flavouring agents, for the production of microbiology media and extracts, as well as livestock feeds. Modern scientific advances allow the isolation, construction and industrial production of new yeast strains to satisfy the specific demands of the food industry. Types of commercial food grade yeasts, industrial production processes and raw materials are highlighted. Aspects of yeast metabolism, with respect to carbohydrate utilization, nutritional aspects and recent research advances are also discussed.

  19. Interaction dynamics of two diffusing particles: contact times and influence of nearby surfaces.

    Science.gov (United States)

    Tränkle, B; Ruh, D; Rohrbach, A

    2016-03-14

    Interactions of diffusing particles are governed by hydrodynamics on different length and timescales. The local hydrodynamics can be influenced substantially by simple interfaces. Here, we investigate the interaction dynamics of two micron-sized spheres close to plane interfaces to mimic more complex biological systems or microfluidic environments. Using scanned line optical tweezers and fast 3D interferometric particle tracking, we are able to track the motion of each bead with precisions of a few nanometers and at a rate of 10 kilohertz. From the recorded trajectories, all spatial and temporal information is accessible. This way, we measure diffusion coefficients for two coupling particles at varying distances h to one or two glass interfaces. We analyze their coupling strength and length by cross-correlation analysis relative to h and find a significant decrease in the coupling length when a second particle diffuses nearby. By analysing the times the particles are in close contact, we find that the influence of nearby surfaces and interaction potentials reduce the diffusivity strongly, although we found that the diffusivity hardly affects the contact times and the binding probability between the particles. All experimental results are compared to a theoretical model, which is based on the number of possible diffusion paths following the Catalan numbers and a diffusion probability, which is biased by the spheres' surface potential. The theoretical and experimental results agree very well and therefore enable a better understanding of hydrodynamically coupled interaction processes.

  20. Rod-shaped silica particles derivatized with elongated silver nanoparticles immobilized within mesopores

    Energy Technology Data Exchange (ETDEWEB)

    Mnasri, Najib [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Charnay, Clarence; Ménorval, Louis-Charles de [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France); Elaloui, Elimame [Materials, Environment and Energy Laboratory (UR14ES26), Faculty of Science, University of Gafsa, 2112 Gafsa (Tunisia); Zajac, Jerzy, E-mail: jerzy.zajac@umontpellier.fr [Institut Charles Gerhardt de Montpellier, CNRS UMR 5253, Université Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 5 (France)

    2016-11-15

    Silver-derivatized silica particles possessing a non-spherical morphology and surface plasmon resonance properties have been achieved. Nanometer-sized silica rods with uniformly sized mesopore channels were prepared first making use of alkyltrimethyl ammonium surfactants as porogens and the 1:0.10 tetraethyl orthosilicate (TEOS) : 3-aminopropyltriethoxysilane (APTES) mixture as a silicon source. Silica rods were subsequently functionalized by introducing elongated silver nanoparticles within the intra-particle mesopores thanks to the AgNO{sub 3} reduction procedure based on the action of hemiaminal groups previously located on the mesopore walls. The textural and structural features of the samples were inferred from the combined characterization studies including SEM and TEM microscopy, nitrogen adsorption-desorption at 77 K, powder XRD in the small- and wide-angle region, as well as UV–visible spectroscopy. {sup 129}Xe NMR spectroscopy appeared particularly useful to obtain a correct information about the porous structure of rod-shaped silica particles and the silver incorporation within their intra-particle mesopores. - Highlights: • Mesoporous monodisperse submicron-sized silica rods were achieved. • Silver nanoparticles were located lengthwise within the intra-particle mesopores. • Textural and plasmonic properties of particles studied by {sup 129}Xe NMR and UV–Vis.