Performance modeling of Deep Burn TRISO fuel using ZrC as a load-bearing layer and an oxygen getter

NASA Astrophysics Data System (ADS)

Wongsawaeng, Doonyapong

2010-01-01

The effects of design choices for the TRISO particle fuel were explored in order to determine their contribution to attaining high-burnup in Deep Burn modular helium reactor fuels containing transuranics from light water reactor spent fuel. The new design features were: (1) ZrC coating substituted for the SiC, allowing the fuel to survive higher accident temperatures; (2) pyrocarbon/SiC "alloy" substituted for the inner pyrocarbon coating to reduce layer failure and (3) pyrocarbon seal coat and thin ZrC oxygen getter coating on the kernel to eliminate CO. Fuel performance was evaluated using General Atomics Company's PISA code. The only acceptable design has a 200-μm kernel diameter coupled with at least 150-μm thick, 50% porosity buffer, a 15-μm ZrC getter over a 10-μm pyrocarbon seal coat on the kernel, an alloy inner pyrocarbon, and ZrC substituted for SiC. The code predicted that during a 1600 °C postulated accident at 70% FIMA, the ZrC failure probability is <10-4.

Irradiation performance of HTGR fuel rods in HFIR experiments HRB-7 and -8

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

Valentine, K.H.; Homan, F.J.; Long, E.L. Jr.

1977-05-01

The HRB-7 and -8 experiments were designed as a comprehensive test of mixed thorium-uranium oxide fissile particles with Th:U ratios from 0 to 8 for HTGR recycle application. In addition, fissile particles derived from Weak-Acid Resin (WAR) were tested as a potential backup type of fissile particle for HTGR recycle. These experiments were conducted at two temperatures (1250 and 1500/sup 0/C) to determine the influence of operating temperature on the performance parameters studied. The minor objectives were comparison of advanced coating designs where ZrC replaced SiC in the Triso design, testing of fuel coated in laboratory-scale equipment with fuel coatedmore » in production-scale coaters, comparison of the performance of /sup 233/U-bearing particles with that of /sup 235/U-bearing particles, comparison of the performance of Biso coatings with Triso coatings for particles containing the same type of kernel, and testing of multijunction tungsten-rhenium thermocouples. All objectives were accomplished. As a result of these experiments the mixed thorium-uranium oxide fissile kernel was replaced by a WAR-derived particle in the reference recycle design. A tentative decision to make this change had been reached before the HRB-7 and -8 capsules were examined, and the results of the examination confirmed the accuracy of the previous decision. Even maximum dilution (Th/U approximately equal to 8) of the mixed thorium-uranium oxide kernel was insufficient to prevent amoeba of the kernels at rates that are unacceptable in a large HTGR. Other results showed the performance of /sup 233/U-bearing particles to be identical to that of /sup 235/U-bearing particles, the performance of fuel coated in production-scale equipment to be at least as good as that of fuel coated in laboratory-scale coaters, the performance of ZrC coatings to be very promising, and Biso coatings to be inferior to Triso coatings relative to fission product retention.« less

Optimized formulas for the gravitational field of a tesseroid

NASA Astrophysics Data System (ADS)

Grombein, Thomas; Seitz, Kurt; Heck, Bernhard

2013-07-01

Various tasks in geodesy, geophysics, and related geosciences require precise information on the impact of mass distributions on gravity field-related quantities, such as the gravitational potential and its partial derivatives. Using forward modeling based on Newton's integral, mass distributions are generally decomposed into regular elementary bodies. In classical approaches, prisms or point mass approximations are mostly utilized. Considering the effect of the sphericity of the Earth, alternative mass modeling methods based on tesseroid bodies (spherical prisms) should be taken into account, particularly in regional and global applications. Expressions for the gravitational field of a point mass are relatively simple when formulated in Cartesian coordinates. In the case of integrating over a tesseroid volume bounded by geocentric spherical coordinates, it will be shown that it is also beneficial to represent the integral kernel in terms of Cartesian coordinates. This considerably simplifies the determination of the tesseroid's potential derivatives in comparison with previously published methodologies that make use of integral kernels expressed in spherical coordinates. Based on this idea, optimized formulas for the gravitational potential of a homogeneous tesseroid and its derivatives up to second-order are elaborated in this paper. These new formulas do not suffer from the polar singularity of the spherical coordinate system and can, therefore, be evaluated for any position on the globe. Since integrals over tesseroid volumes cannot be solved analytically, the numerical evaluation is achieved by means of expanding the integral kernel in a Taylor series with fourth-order error in the spatial coordinates of the integration point. As the structure of the Cartesian integral kernel is substantially simplified, Taylor coefficients can be represented in a compact and computationally attractive form. Thus, the use of the optimized tesseroid formulas particularly benefits from a significant decrease in computation time by about 45 % compared to previously used algorithms. In order to show the computational efficiency and to validate the mathematical derivations, the new tesseroid formulas are applied to two realistic numerical experiments and are compared to previously published tesseroid methods and the conventional prism approach.

Deposition of Coatings for Raising the Wear Resistance of Friction Surfaces of Spherical Sliding Bearings

NASA Astrophysics Data System (ADS)

Gorlenko, A. O.; Davydov, S. V.

2018-01-01

The process of finishing plasma hardening with deposition of a multilayer amorphous coating of the Si - O - C - N system is considered as applied to hardening of the friction surfaces of spherical sliding bearings. The microrelief, the submicrorelief, and the tribological characteristics of the deposited wear-resistant antifriction amorphous coating, which are responsible for the elevated wear resistance of spherical sliding bearings, are investigated.

Data Compilation for AGR-3/4 Designed-to-Fail (DTF) Fuel Particle Batch LEU04-02DTF

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

Hunn, John D; Miller, James Henry

2008-10-01

This document is a compilation of coating and characterization data for the AGR-3/4 designed-to-fail (DTF) particles. The DTF coating is a high density, high anisotropy pyrocarbon coating of nominal 20 {micro}m thickness that is deposited directly on the kernel. The purpose of this coating is to fail early in the irradiation, resulting in a controlled release of fission products which can be analyzed to provide data on fission product transport. A small number of DTF particles will be included with standard TRISO driver fuel particles in the AGR-3 and AGR-4 compacts. The ORNL Coated Particle Fuel Development Laboratory 50-mm diametermore » fluidized bed coater was used to coat the DTF particles. The coatings were produced using procedures and process parameters that were developed in an earlier phase of the project as documented in 'Summary Report on the Development of Procedures for the Fabrication of AGR-3/4 Design-to-Fail Particles', ORNL/TM-2008/161. Two coating runs were conducted using the approved coating parameters. NUCO425-06DTF was a final process qualification batch using natural enrichment uranium carbide/uranium oxide (UCO) kernels. After the qualification run, LEU04-02DTF was produced using low enriched UCO kernels. Both runs were inspected and determined to meet the specifications for DTF particles in section 5 of the AGR-3 & 4 Fuel Product Specification (EDF-6638, Rev.1). Table 1 provides a summary of key properties of the DTF layer. For comparison purposes, an archive sample of DTF particles produced by General Atomics was characterized using identical methods. This data is also summarized in Table 1.« less

Production of LEU Fully Ceramic Microencapsulated Fuel for Irradiation Testing

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

Terrani, Kurt A; Kiggans Jr, James O; McMurray, Jake W

2016-01-01

Fully Ceramic Microencapsulated (FCM) fuel consists of tristructural isotropic (TRISO) fuel particles embedded inside a SiC matrix. This fuel inherently possesses multiple barriers to fission product release, namely the various coating layers in the TRISO fuel particle as well as the dense SiC matrix that hosts these particles. This coupled with the excellent oxidation resistance of the SiC matrix and the SiC coating layer in the TRISO particle designate this concept as an accident tolerant fuel (ATF). The FCM fuel takes advantage of uranium nitride kernels instead of oxide or oxide-carbide kernels used in high temperature gas reactors to enhancemore » heavy metal loading in the highly moderated LWRs. Production of these kernels with appropriate density, coating layer development to produce UN TRISO particles, and consolidation of these particles inside a SiC matrix have been codified thanks to significant R&D supported by US DOE Fuel Cycle R&D program. Also, surrogate FCM pellets (pellets with zirconia instead of uranium-bearing kernels) have been neutron irradiated and the stability of the matrix and coating layer under LWR irradiation conditions have been established. Currently the focus is on production of LEU (7.3% U-235 enrichment) FCM pellets to be utilized for irradiation testing. The irradiation is planned at INL s Advanced Test Reactor (ATR). This is a critical step in development of this fuel concept to establish the ability of this fuel to retain fission products under prototypical irradiation conditions.« less

Microscopic analysis of irradiated AGR-1 coated particle fuel compacts

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

Scott A. Ploger; Paul A. Demkowicz; John D. Hunn

The AGR-1 experiment involved irradiation of 72 TRISO-coated particle fuel compacts to a peak compact-average burnup of 19.5% FIMA with no in-pile failures observed out of 3 x 105 total particles. Irradiated AGR-1 fuel compacts have been cross-sectioned and analyzed with optical microscopy to characterize kernel, buffer, and coating behavior. Six compacts have been examined, spanning a range of irradiation conditions (burnup, fast fluence, and irradiation temperature) and including all four TRISO coating variations irradiated in the AGR-1 experiment. The cylindrical specimens were sectioned both transversely and longitudinally, then polished to expose from 36 to 79 individual particles near midplanemore » on each mount. The analysis focused primarily on kernel swelling and porosity, buffer densification and fracturing, buffer–IPyC debonding, and fractures in the IPyC and SiC layers. Characteristic morphologies have been identified, 981 particles have been classified, and spatial distributions of particle types have been mapped. No significant spatial patterns were discovered in these cross sections. However, some trends were found between morphological types and certain behavioral aspects. Buffer fractures were found in 23% of the particles, and these fractures often resulted in unconstrained kernel protrusion into the open cavities. Fractured buffers and buffers that stayed bonded to IPyC layers appear related to larger pore size in kernels. Buffer–IPyC interface integrity evidently factored into initiation of rare IPyC fractures. Fractures through part of the SiC layer were found in only four classified particles, all in conjunction with IPyC–SiC debonding. Compiled results suggest that the deliberate coating fabrication variations influenced the frequencies of IPyC fractures and IPyC–SiC debonds.« less

An investigation of the generation and properties of laboratory-produced ball lightning

NASA Astrophysics Data System (ADS)

Oreshko, A. G.

2015-06-01

The experiments revealed that ball lightning is a self-confining quasi-neutral in a whole plasma system that rotates around its axis. Ball lightning has a structure of a spherical electric domain, consisting of a kernel with excess negative charge and an external spherical layer with excess positive charge. The excess of charges of one sort and the lack of charges of the other sort in the kernel or in the external spherical layer significantly reduces the possibility of electron capture by means of an electric field, created by the nearest ions and leads to a drastic slowdown of recombination process. Direct proof has been obtained that inside of ball lightning - in an external spherical layer that rotates around the axis - there is a circular current of sub-relativistic particles. This current creates and maintains its own poloidal magnetic field of ball lightning, i.e. it carries out the function of magnetic dynamo. The kernel of ball lightning is situated in a region with minimum values of induction of the magnetic field. The inequality of positive and negative charges in elements of ball lightning also significantly reduces losses of the charged plasma on bremsstrahlung. Ball lightning generation occurs in a plasmic vortex. The ball lightning energy in the region of its generation significantly differs from the ball lightning energy, which is drifting in space. The axial component of kinetic energy of particles slightly exceeds 100 keV and the rotational component of the ions energy is a bit greater than 1 MeV. Ball lightning is `embedded' in atmosphere autonomous accelerator of charged particles of a cyclotron type due to self-generation of strong crossed electric and magnetic fields. A discussion of the conditions of stability and long-term existence of ball lightning is given.

Evaluation of Optimal Formulas for Gravitational Tensors up to Gravitational Curvatures of a Tesseroid

NASA Astrophysics Data System (ADS)

Deng, Xiao-Le; Shen, Wen-Bin

2018-01-01

The forward modeling of the topographic effects of the gravitational parameters in the gravity field is a fundamental topic in geodesy and geophysics. Since the gravitational effects, including for instance the gravitational potential (GP), the gravity vector (GV) and the gravity gradient tensor (GGT), of the topographic (or isostatic) mass reduction have been expanded by adding the gravitational curvatures (GC) in geoscience, it is crucial to find efficient numerical approaches to evaluate these effects. In this paper, the GC formulas of a tesseroid in Cartesian integral kernels are derived in 3D/2D forms. Three generally used numerical approaches for computing the topographic effects (e.g., GP, GV, GGT, GC) of a tesseroid are studied, including the Taylor Series Expansion (TSE), Gauss-Legendre Quadrature (GLQ) and Newton-Cotes Quadrature (NCQ) approaches. Numerical investigations show that the GC formulas in Cartesian integral kernels are more efficient if compared to the previously given GC formulas in spherical integral kernels: by exploiting the 3D TSE second-order formulas, the computational burden associated with the former is 46%, as an average, of that associated with the latter. The GLQ behaves better than the 3D/2D TSE and NCQ in terms of accuracy and computational time. In addition, the effects of a spherical shell's thickness and large-scale geocentric distance on the GP, GV, GGT and GC functionals have been studied with the 3D TSE second-order formulas as well. The relative approximation errors of the GC functionals are larger with the thicker spherical shell, which are the same as those of the GP, GV and GGT. Finally, the very-near-area problem and polar singularity problem have been considered by the numerical methods of the 3D TSE, GLQ and NCQ. The relative approximation errors of the GC components are larger than those of the GP, GV and GGT, especially at the very near area. Compared to the GC formulas in spherical integral kernels, these new GC formulas can avoid the polar singularity problem.

Analysis and fabrication of tungsten CERMET materials for ultra-high temperature reactor applications via pulsed electric current sintering

NASA Astrophysics Data System (ADS)

Webb, Jonathan A.

The optimized development path for the fabrication of ultra-high temperature W-UO2 CERMET fuel elements were explored within this dissertation. A robust literature search was conducted, which concluded that a W-UO 2 fuel element must contain a fine tungsten microstructure and spherical UO2 kernels throughout the entire consolidation process. Combined Monte Carlo and Computational Fluid Dynamics (CFD) analysis were used to determine the effects of rhenium and gadolinia additions on the performance of W-UO 2 fuel elements at refractory temperatures and in dry and water submerged environments. The computational analysis also led to the design of quasi-optimized fuel elements that can meet thermal-hydraulic and neutronic requirements A rigorous set of experiments were conducted to determine if Pulsed Electric Current Sintering (PECS) can fabricate tungsten and W-Ce02 specimens to the required geometries, densities and microstructures required for high temperature fuel elements as well as determine the mechanisms involved within the PECS consolidation process. The CeO2 acts as a surrogate for UO 2 fuel kernels in these experiments. The experiments seemed to confirm that PECS consolidation takes place via diffusional mass transfer methods; however, the densification process is rapidly accelerated due to the effects of current densities within the consolidating specimen. Fortunately the grain growth proceeds at a traditional rate and the PECS process can yield near fully dense W and W-Ce02 specimens with a finer microstructure than other sintering techniques. PECS consolidation techniques were also shown to be capable of producing W-UO2 segments at near-prototypic geometries; however, great care must be taken to coat the fuel particles with tungsten prior to sintering. Also, great care must be taken to ensure that the particles remain spherical in geometry under the influence of a uniaxial stress as applied during PECS, which involves mixing different fuel kernel sizes in order to reduce the porosity in the initial green compact. Particle mixing techniques were also shown to be capable of producing consolidated CERMETs, but with a less than desirable microstructure. The work presented herin will help in the development of very high temperature reactors for terrestrial and space missions in the future.

Acceptance Test Data for BWXT Coated Particle Batches 93172B and 93173B—Defective IPyC and Pyrocarbon Anisotropy

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

Hunn, John D.; Helmreich, Grant W.; Dyer, John A.

Coated particle batches J52O-16-93172B and J52O-16-93173B were produced by Babcock and Wilcox Technologies (BWXT) as part of the production campaign for the Advanced Gas Reactor Fuel Development and Qualification (AGR) Program’s AGR-5/6/7 irradiation test in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR), but were not used in the final fuel composite. However, these batches may be used as demonstration production-scale coated particle fuel for other experiments. Each batch was coated in a 150-mm-diameter production-scale fluidized-bed chemical vapor deposition (CVD) furnace. Tristructural isotropic (TRISO) coatings were deposited on 425-μm-nominal-diameter spherical kernels from BWXT lot J52R-16-69317 containing a mixture ofmore » 15.5%-enriched uranium carbide and uranium oxide (UCO). The TRISO coatings consisted of four consecutive CVD layers: a ~50% dense carbon buffer layer with 100-μm-nominal thickness, a dense inner pyrolytic carbon (IPyC) layer with 40-μm-nominal thickness, a silicon carbide (SiC) layer with 35-μm-nominal thickness, and a dense outer pyrolytic carbon (OPyC) layer with 40-μm-nominal thickness. The TRISO-coated particle batches were sieved to upgrade the particles by removing over-sized and under-sized material, and the upgraded batches were designated by appending the letter A to the end of the batch number (e.g., 93172A). Secondary upgrading by sieving was performed on the A-designated batches to remove particles with missing or very-thin buffer layers that were identified during previous analysis of the individual batches for defective IPyC, as reported in the acceptance test data report for the AGR-5/6/7 production batches [Hunn et al. 2017b]. The additionally-upgraded batches were designated by appending the letter B to the end of the batch number (e.g., 93172B).« less

A multi-label learning based kernel automatic recommendation method for support vector machine.

PubMed

Zhang, Xueying; Song, Qinbao

2015-01-01

Choosing an appropriate kernel is very important and critical when classifying a new problem with Support Vector Machine. So far, more attention has been paid on constructing new kernels and choosing suitable parameter values for a specific kernel function, but less on kernel selection. Furthermore, most of current kernel selection methods focus on seeking a best kernel with the highest classification accuracy via cross-validation, they are time consuming and ignore the differences among the number of support vectors and the CPU time of SVM with different kernels. Considering the tradeoff between classification success ratio and CPU time, there may be multiple kernel functions performing equally well on the same classification problem. Aiming to automatically select those appropriate kernel functions for a given data set, we propose a multi-label learning based kernel recommendation method built on the data characteristics. For each data set, the meta-knowledge data base is first created by extracting the feature vector of data characteristics and identifying the corresponding applicable kernel set. Then the kernel recommendation model is constructed on the generated meta-knowledge data base with the multi-label classification method. Finally, the appropriate kernel functions are recommended to a new data set by the recommendation model according to the characteristics of the new data set. Extensive experiments over 132 UCI benchmark data sets, with five different types of data set characteristics, eleven typical kernels (Linear, Polynomial, Radial Basis Function, Sigmoidal function, Laplace, Multiquadric, Rational Quadratic, Spherical, Spline, Wave and Circular), and five multi-label classification methods demonstrate that, compared with the existing kernel selection methods and the most widely used RBF kernel function, SVM with the kernel function recommended by our proposed method achieved the highest classification performance.

A Multi-Label Learning Based Kernel Automatic Recommendation Method for Support Vector Machine

PubMed Central

Zhang, Xueying; Song, Qinbao

2015-01-01

Choosing an appropriate kernel is very important and critical when classifying a new problem with Support Vector Machine. So far, more attention has been paid on constructing new kernels and choosing suitable parameter values for a specific kernel function, but less on kernel selection. Furthermore, most of current kernel selection methods focus on seeking a best kernel with the highest classification accuracy via cross-validation, they are time consuming and ignore the differences among the number of support vectors and the CPU time of SVM with different kernels. Considering the tradeoff between classification success ratio and CPU time, there may be multiple kernel functions performing equally well on the same classification problem. Aiming to automatically select those appropriate kernel functions for a given data set, we propose a multi-label learning based kernel recommendation method built on the data characteristics. For each data set, the meta-knowledge data base is first created by extracting the feature vector of data characteristics and identifying the corresponding applicable kernel set. Then the kernel recommendation model is constructed on the generated meta-knowledge data base with the multi-label classification method. Finally, the appropriate kernel functions are recommended to a new data set by the recommendation model according to the characteristics of the new data set. Extensive experiments over 132 UCI benchmark data sets, with five different types of data set characteristics, eleven typical kernels (Linear, Polynomial, Radial Basis Function, Sigmoidal function, Laplace, Multiquadric, Rational Quadratic, Spherical, Spline, Wave and Circular), and five multi-label classification methods demonstrate that, compared with the existing kernel selection methods and the most widely used RBF kernel function, SVM with the kernel function recommended by our proposed method achieved the highest classification performance. PMID:25893896

Earth Structure, Ice Mass Changes, and the Local Dynamic Geoid

NASA Astrophysics Data System (ADS)

Harig, C.; Simons, F. J.

2014-12-01

Spherical Slepian localization functions are a useful method for studying regional mass changes observed by satellite gravimetry. By projecting data onto a sparse basis set, the local field can be estimated more easily than with the full spherical harmonic basis. We have used this method previously to estimate the ice mass change in Greenland from GRACE data, and it can also be applied to other planetary problems such as global magnetic fields. Earth's static geoid, in contrast to the time-variable field, is in large part related to the internal density and rheological structure of the Earth. Past studies have used dynamic geoid kernels to relate this density structure and the internal deformation it induces to the surface geopotential at large scales. These now classical studies of the eighties and nineties were able to estimate the mantle's radial rheological profile, placing constraints on the ratio between upper and lower mantle viscosity. By combining these two methods, spherical Slepian localization and dynamic geoid kernels, we have created local dynamic geoid kernels which are sensitive only to density variations within an area of interest. With these kernels we can estimate the approximate local radial rheological structure that best explains the locally observed geoid on a regional basis. First-order differences of the regional mantle viscosity structure are accessible to this technique. In this contribution we present our latest, as yet unpublished results on the geographical and temporal pattern of ice mass changes in Antarctica over the past decade, and we introduce a new approach to extract regional information about the internal structure of the Earth from the static global gravity field. Both sets of results are linked in terms of the relevant physics, but also in being developed from the marriage of Slepian functions and geoid kernels. We make predictions on the utility of our approach to derive fully three-dimensional rheological Earth models, to be used for corrections for glacio-isostatic adjustment, as necessary for the interpretation of time-variable gravity observations in terms of ice sheet mass-balance studies.

Simultaneous estimation of phenolic acids in sea buckthorn (Hippophaë rhamnoides) using RP-HPLC with DAD.

PubMed

Arimboor, Ranjith; Kumar, K Sarin; Arumughan, C

2008-05-12

A RP-HPLC-DAD method was developed and validated for the simultaneous analysis of nine phenolic acids including gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, salicylic acid, p-coumaric acid, cinnamic acid, caffiec acid and ferulic acid in sea buckthorn (SB) (Hippophaë rhamnoides) berries and leaves. The method was validated in terms of linearity, LOD, precision, accuracy and recovery and found to be satisfactory. Phenolic acid derivatives in anatomical parts of SB berries and leaves were separated into free phenolic acids, phenolic acids bound as esters and phenolic acids bound as glycosides and profiled in HPLC. Berry pulp contained a total of 1068 mg/kg phenolic acids, of which 58.8% was derived from phenolic glycosides. Free phenolic acids and phenolic acid esters constituted 20.0% and 21.2%, respectively, of total phenolic acids in SB berry pulp. The total phenolic acid content in seed kernel (5741 mg/kg) was higher than that in berry pulp and seed coat (Table 2). Phenolic acids liberated from soluble esters constituted the major fraction of phenolic acids (57.3% of total phenolic acids) in seed kernel. 8.4% and 34.3% of total phenolic acids in seed kernel were, respectively contributed by free and phenolic acids liberated from glycosidic bonds. The total soluble phenolic acids content in seed coat (448 mg/kg) was lower than that in seed kernel and pulp (Table 2). Proportion of free phenolic acids in total phenolic acids in seed coat was higher than that in seed kernel and pulp. Phenolic acids bound as esters and glycosides, respectively contributed 49.1% and 20.3% of total phenolic acids in seed coat. The major fraction (approximately 70%) of phenolic acids in SB berries was found to be concentrated in the seeds. Gallic acid was the predominant phenolic acid both in free and bound forms in SB berry parts and leaves.

Some physical properties of ginkgo nuts and kernels

NASA Astrophysics Data System (ADS)

Ch'ng, P. E.; Abdullah, M. H. R. O.; Mathai, E. J.; Yunus, N. A.

2013-12-01

Some data of the physical properties of ginkgo nuts at a moisture content of 45.53% (±2.07) (wet basis) and of their kernels at 60.13% (± 2.00) (wet basis) are presented in this paper. It consists of the estimation of the mean length, width, thickness, the geometric mean diameter, sphericity, aspect ratio, unit mass, surface area, volume, true density, bulk density, and porosity measures. The coefficient of static friction for nuts and kernels was determined by using plywood, glass, rubber, and galvanized steel sheet. The data are essential in the field of food engineering especially dealing with design and development of machines, and equipment for processing and handling agriculture products.

Computational investigation of intense short-wavelength laser interaction with rare gas clusters

NASA Astrophysics Data System (ADS)

Bigaouette, Nicolas

Current Very High Temperature Reactor designs incorporate TRi-structural ISOtropic (TRISO) particle fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel by dropping a cold precursor solution into a column of hot trichloroethylene (TCE). The temperature difference drives the liquid precursor solution to precipitate the metal solution into gel spheres before reaching the bottom of a production column. Over time, gelation byproducts inhibit complete gelation and the TCE must be purified or discarded. The resulting mixed-waste stream is expensive to dispose of or recycle, and changing the forming fluid to a non-hazardous alternative could greatly improve the economics of kernel production. Selection criteria for a replacement forming fluid narrowed a list of ~10,800 chemicals to yield ten potential replacements. The physical properties of the alternatives were measured as a function of temperature between 25 °C and 80 °C. Calculated terminal velocities and heat transfer rates provided an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane were selected for further testing, and surrogate yttria-stabilized zirconia (YSZ) kernels were produced using these selected fluids. The kernels were characterized for density, geometry, composition, and crystallinity and compared to a control group of kernels produced in silicone oil. Production in 1-bromotetradecane showed positive results, producing dense (93.8 %TD) and spherical (1.03 aspect ratio) kernels, but proper gelation did not occur in the other alternative forming fluids. With many of the YSZ kernels not properly gelling within the length of the column, this project further investigated the heat transfer properties of the forming fluids and precursor solution. A sensitivity study revealed that the heat transfer properties of the precursor solution have the strongest impact on gelation time. A COMSOL heat transfer model estimated an effective thermal diffusivity range for the YSZ precursor solution as 1.13x10 -8 m2/s to 3.35x10-8 m 2/s, which is an order of magnitude smaller than the value used in previous studies. 1-bromotetradecane is recommended for further investigation with the production of uranium-based kernels.

Spherical cloaking using nonlinear transformations for improved segmentation into concentric isotropic coatings.

PubMed

Qiu, Cheng-Wei; Hu, Li; Zhang, Baile; Wu, Bae-Ian; Johnson, Steven G; Joannopoulos, John D

2009-08-03

Two novel classes of spherical invisibility cloaks based on nonlinear transformation have been studied. The cloaking characteristics are presented by segmenting the nonlinear transformation based spherical cloak into concentric isotropic homogeneous coatings. Detailed investigations of the optimal discretization (e.g., thickness control of each layer, nonlinear factor, etc.) are presented for both linear and nonlinear spherical cloaks and their effects on invisibility performance are also discussed. The cloaking properties and our choice of optimal segmentation are verified by the numerical simulation of not only near-field electric-field distribution but also the far-field radar cross section (RCS).

A fast algorithm for forward-modeling of gravitational fields in spherical coordinates with 3D Gauss-Legendre quadrature

NASA Astrophysics Data System (ADS)

Zhao, G.; Liu, J.; Chen, B.; Guo, R.; Chen, L.

2017-12-01

Forward modeling of gravitational fields at large-scale requires to consider the curvature of the Earth and to evaluate the Newton's volume integral in spherical coordinates. To acquire fast and accurate gravitational effects for subsurface structures, subsurface mass distribution is usually discretized into small spherical prisms (called tesseroids). The gravity fields of tesseroids are generally calculated numerically. One of the commonly used numerical methods is the 3D Gauss-Legendre quadrature (GLQ). However, the traditional GLQ integration suffers from low computational efficiency and relatively poor accuracy when the observation surface is close to the source region. We developed a fast and high accuracy 3D GLQ integration based on the equivalence of kernel matrix, adaptive discretization and parallelization using OpenMP. The equivalence of kernel matrix strategy increases efficiency and reduces memory consumption by calculating and storing the same matrix elements in each kernel matrix just one time. In this method, the adaptive discretization strategy is used to improve the accuracy. The numerical investigations show that the executing time of the proposed method is reduced by two orders of magnitude compared with the traditional method that without these optimized strategies. High accuracy results can also be guaranteed no matter how close the computation points to the source region. In addition, the algorithm dramatically reduces the memory requirement by N times compared with the traditional method, where N is the number of discretization of the source region in the longitudinal direction. It makes the large-scale gravity forward modeling and inversion with a fine discretization possible.

Fast algorithms for evaluating the stress field of dislocation lines in anisotropic elastic media

NASA Astrophysics Data System (ADS)

Chen, C.; Aubry, S.; Oppelstrup, T.; Arsenlis, A.; Darve, E.

2018-06-01

In dislocation dynamics (DD) simulations, the most computationally intensive step is the evaluation of the elastic interaction forces among dislocation ensembles. Because the pair-wise interaction between dislocations is long-range, this force calculation step can be significantly accelerated by the fast multipole method (FMM). We implemented and compared four different methods in isotropic and anisotropic elastic media: one based on the Taylor series expansion (Taylor FMM), one based on the spherical harmonics expansion (Spherical FMM), one kernel-independent method based on the Chebyshev interpolation (Chebyshev FMM), and a new kernel-independent method that we call the Lagrange FMM. The Taylor FMM is an existing method, used in ParaDiS, one of the most popular DD simulation softwares. The Spherical FMM employs a more compact multipole representation than the Taylor FMM does and is thus more efficient. However, both the Taylor FMM and the Spherical FMM are difficult to derive in anisotropic elastic media because the interaction force is complex and has no closed analytical formula. The Chebyshev FMM requires only being able to evaluate the interaction between dislocations and thus can be applied easily in anisotropic elastic media. But it has a relatively large memory footprint, which limits its usage. The Lagrange FMM was designed to be a memory-efficient black-box method. Various numerical experiments are presented to demonstrate the convergence and the scalability of the four methods.

21 CFR 172.861 - Cocoa butter substitute from coconut oil, palm kernel oil, or both oils.

Code of Federal Regulations, 2010 CFR

2010-04-01

... fatty acids (complying with § 172.860) derived from edible coconut oil, edible palm kernel oil, or both oils. (b) The ingredient meets the following specifications: Acid number: Not to exceed 0.5..., citric acid, succinic acid, and spices; and (2) In compound coatings, cocoa creams, cocoa-based sweets...

On the critical flame radius and minimum ignition energy for spherical flame initiation

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

Chen, Zheng; Burke, M. P.; Ju, Yiguang

2011-01-01

Spherical flame initiation from an ignition kernel is studied theoretically and numerically using different fuel/oxygen/helium/argon mixtures (fuel: hydrogen, methane, and propane). The emphasis is placed on investigating the critical flame radius controlling spherical flame initiation and its correlation with the minimum ignition energy. It is found that the critical flame radius is different from the flame thickness and the flame ball radius and that their relationship depends strongly on the Lewis number. Three different flame regimes in terms of the Lewis number are observed and a new criterion for the critical flame radius is introduced. For mixtures with Lewis numbermore » larger than a critical Lewis number above unity, the critical flame radius is smaller than the flame ball radius but larger than the flame thickness. As a result, the minimum ignition energy can be substantially over-predicted (under-predicted) based on the flame ball radius (the flame thickness). The results also show that the minimum ignition energy for successful spherical flame initiation is proportional to the cube of the critical flame radius. Furthermore, preferential diffusion of heat and mass (i.e. the Lewis number effect) is found to play an important role in both spherical flame initiation and flame kernel evolution after ignition. It is shown that the critical flame radius and the minimum ignition energy increase significantly with the Lewis number. Therefore, for transportation fuels with large Lewis numbers, blending of small molecule fuels or thermal and catalytic cracking will significantly reduce the minimum ignition energy.« less

Manufacturing and coating of optical components for the EnMAP hyperspectral imager

NASA Astrophysics Data System (ADS)

Schürmann, M.; Gäbler, D.; Schlegel, R.; Schwinde, S.; Peschel, T.; Damm, C.; Jende, R.; Kinast, J.; Müller, S.; Beier, M.; Risse, S.; Sang, B.; Glier, M.; Bittner, H.; Erhard, M.

2016-07-01

The optical system of the hyperspectral imager of the Environmental Mapping and Analysis Program (EnMAP) consists of a three-mirror anastigmat (TMA) and two independent spectrometers working in the VNIR and SWIR spectral range, respectively. The VNIR spectrometer includes a spherical NiP coated Al6061 mirror that has been ultra-precisely diamond turned and finally coated with protected silver as well as four curved fused silica (FS) and flint glass (SF6) prisms, respectively, each with broadband antireflection (AR) coating, while the backs of the two outer prisms are coated with a high-reflective coating. For AR coating, plasma ion assisted deposition (PIAD) has been used; the high-reflective enhanced Ag-coating on the backside has been deposited by magnetron sputtering. The SWIR spectrometer contains four plane and spherical gold-coated mirrors, respectively, and two curved FS prisms with a broadband antireflection coating. Details about the ultra-precise manufacturing of metal mirrors and prisms as well as their coating are presented in this work.

Investigation on MoS2 and graphite coatings and their effects on the tribological properties of the radial spherical plain bearings

NASA Astrophysics Data System (ADS)

Qiu, Ming; Lu, Jianjun; Li, Yingchun; Lv, Guisen

2016-07-01

With constant enlargement of the application areas of the spherical plain bearings, higher quality lubrication of the bearings is required. To solve the lubricating problems of spherical plain bearings under high temperature, high vacuum, high speed, heavy loads and strong oxidation conditions, it is urgent for us to develop more excellent self-lubricating technologies. In this paper, the bonded solid lubricant coatings, which use inorganic phosphate as the binder, the mixture of MoS2 and graphite with two different weight proportions as the solid lubricant, are prepared by spraying under three different spray gun pressures. The bonding strength tests on the coatings show that the best spraying pressure is 0.2 MPa and the better mixing proportion of MoS2 to Graphite is 3:1. Then for the radial spherical plain bearings with steel/steel friction pair, after the coatings are made on the inner ring outer surfaces, the friction coefficient, the wear loss and the friction temperature of the bearings under four oscillating frequencies are investigated by a self-made tribo-tester. The test results, SEM of the worn morphologies and EDS of worn areas show that tribological properties of the bearing are obviously improved by the bonded solid lubricant coatings. When sprayed under the spray gun pressure of 0.2 MPa, the bearings have better anti-friction and anti-wear properties than those sprayed under 0.1 MPa and 0.3 MPa. Further as proved from the XPS analysis, between the coating with 3:1 mixing ratio of MoS2 to Graphite and the coating with 1:1 ratio, the former has less oxidation occurred on the surface and therefore has better tribological characteristics than the latter. This paper provides a reference to developing a new product of the radial spherical plain bearings with high bonding strength, oxidation resistance and abrasion resistance.

Intelligent Control of a Sensor-Actuator System via Kernelized Least-Squares Policy Iteration

PubMed Central

Liu, Bo; Chen, Sanfeng; Li, Shuai; Liang, Yongsheng

2012-01-01

In this paper a new framework, called Compressive Kernelized Reinforcement Learning (CKRL), for computing near-optimal policies in sequential decision making with uncertainty is proposed via incorporating the non-adaptive data-independent Random Projections and nonparametric Kernelized Least-squares Policy Iteration (KLSPI). Random Projections are a fast, non-adaptive dimensionality reduction framework in which high-dimensionality data is projected onto a random lower-dimension subspace via spherically random rotation and coordination sampling. KLSPI introduce kernel trick into the LSPI framework for Reinforcement Learning, often achieving faster convergence and providing automatic feature selection via various kernel sparsification approaches. In this approach, policies are computed in a low-dimensional subspace generated by projecting the high-dimensional features onto a set of random basis. We first show how Random Projections constitute an efficient sparsification technique and how our method often converges faster than regular LSPI, while at lower computational costs. Theoretical foundation underlying this approach is a fast approximation of Singular Value Decomposition (SVD). Finally, simulation results are exhibited on benchmark MDP domains, which confirm gains both in computation time and in performance in large feature spaces. PMID:22736969

About the role of phase matching between a coated microsphere and a tapered fiber: experimental study.

PubMed

Ristić, Davor; Rasoloniaina, Alphonse; Chiappini, Andrea; Féron, Patrice; Pelli, Stefano; Conti, Gualtiero Nunzi; Ivanda, Mile; Righini, Giancarlo C; Cibiel, Gilles; Ferrari, Maurizio

2013-09-09

Coatings of spherical optical microresonators are widely employed for different applications. Here the effect of the thickness of a homogeneous coating layer on the coupling of light from a tapered fiber to a coated microsphere has been studied. Spherical silica microresonators were coated using a 70SiO(2)- 30HfO(2) glass doped with 0.3 mol% Er(3+) ions. The coupling of a 1480 nm pump laser inside the sphere has been assessed using a tapered optical fiber and observing the 1530-1580 nm Er(3+) emission outcoupled to the same tapered fiber. The measurements were done for different coating thicknesses and compared with theoretical calculations to understand the relationship of the detected signal with the whispering gallery mode electric field profiles.

Accumulation of primary and secondary metabolites in edible jackfruit seed tissues and scavenging of reactive nitrogen species.

PubMed

Fernandes, Fátima; Ferreres, Federico; Gil-Izquierdo, Angel; Oliveira, Andreia P; Valentão, Patrícia; Andrade, Paula B

2017-10-15

Studies involving jackfruit tree (Artocarpus heterophyllus Lam.) focus on its fruit. Nevertheless a considerable part of jackfruit weight is represented by its seeds. Despite being consumed in several countries, knowledge about the chemical composition of these seeds is scarce. In this work, the accumulation of primary and secondary metabolites in jackfruit seed kernel and seed coating membrane was studied. Sixty-seven compounds were identified, sixty of them being reported for the first time in jackfruit seed. Both tissues had a similar qualitative profile, but significant quantitative differences were found. The capacity of aqueous extracts from jackfruit seed kernel and seed coating membranes to scavenge nitric oxide radical was also evaluated for the first time, the extract prepared from the seed coating membrane being the most potent. This work increases the potential revenue from a food that is still largely wasted. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pyrolytic carbon-coated nuclear fuel

DOEpatents

Lindemer, Terrence B.; Long, Jr., Ernest L.; Beatty, Ronald L.

1978-01-01

An improved nuclear fuel kernel having at least one pyrolytic carbon coating and a silicon carbon layer is provided in which extensive interaction of fission product lanthanides with the silicon carbon layer is avoided by providing sufficient UO.sub.2 to maintain the lanthanides as oxides during in-reactor use of said fuel.

Nature and composition of fat bloom from palm kernel stearin and hydrogenated palm kernel stearin compound chocolates.

PubMed

Smith, Kevin W; Cain, Fred W; Talbot, Geoff

2004-08-25

Palm kernel stearin and hydrogenated palm kernel stearin can be used to prepare compound chocolate bars or coatings. The objective of this study was to characterize the chemical composition, polymorphism, and melting behavior of the bloom that develops on bars of compound chocolate prepared using these fats. Bars were stored for 1 year at 15, 20, or 25 degrees C. At 15 and 20 degrees C the bloom was enriched in cocoa butter triacylglycerols, with respect to the main fat phase, whereas at 25 degrees C the enrichment was with palm kernel triacylglycerols. The bloom consisted principally of solid fat and was sharper melting than was the fat in the chocolate. Polymorphic transitions from the initial beta' phase to the beta phase accompanied the formation of bloom at all temperatures.

Multiscale Experimental and Numerical Approach to the Powder Particle Shape Effect on Al-Al2O3 Coating Build-Up

NASA Astrophysics Data System (ADS)

Leger, P. E.; Sennour, M.; Delloro, F.; Borit, F.; Debray, A.; Gaslain, F.; Jeandin, M.; Ducos, M.

2017-10-01

Aluminum (Al) powders with spherical and irregular particle shapes were mixed with two alumina (Al2O3) powders with either a spherical or an angular particle shape to achieve high-performance cold-sprayed coatings onto steel. Two effects of the aluminum particle shape were observed. First, coating microstructure observation showed impinging heterogeneity depending on particle shape. Second, particle jet differences depending on particle morphology were shown by velocity maps. From the latter, SEM and XRD, three effects of the alumina particle shape were also shown, i.e., higher in-flight velocity of angular particles, fragmentation of spherical hollow particles and embedding of alumina particles with aluminum. Numerical simulation of particle impacts was developed to study the densification of Al coating due to Al2O3 addition through elucidation of Al-Al2O3 interaction behavior at the scale of the coating. Al/Al and Al/Al2O3 interfaces were investigated using TEM to understand coating strengthening effects due to alumina addition at the scale of the particle. As a whole, Al and Al2O3 particle shape effects were claimed to explain coating mechanical properties, e.g., microhardness and coating-substrate bond strength. This study resulted in specifying criteria to help cold spray users in selecting powders for their applications, to meet economic and technical requirements.

ADVANCING THE FUNDAMENTAL UNDERSTANDING AND SCALE-UP OF TRISO FUEL COATERS VIA ADVANCED MEASUREMENT AND COMPUTATIONAL TECHNIQUES

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

Biswas, Pratim; Al-Dahhan, Muthanna

2012-11-01

Tri-isotropic (TRISO) fuel particle coating is critical for the future use of nuclear energy produced byadvanced gas reactors (AGRs). The fuel kernels are coated using chemical vapor deposition in a spouted fluidized bed. The challenges encountered in operating TRISO fuel coaters are due to the fact that in modern AGRs, such as High Temperature Gas Reactors (HTGRs), the acceptable level of defective/failed coated particles is essentially zero. This specification requires processes that produce coated spherical particles with even coatings having extremely low defect fractions. Unfortunately, the scale-up and design of the current processes and coaters have been based on empiricalmore » approaches and are operated as black boxes. Hence, a voluminous amount of experimental development and trial and error work has been conducted. It has been clearly demonstrated that the quality of the coating applied to the fuel kernels is impacted by the hydrodynamics, solids flow field, and flow regime characteristics of the spouted bed coaters, which themselves are influenced by design parameters and operating variables. Further complicating the outlook for future fuel-coating technology and nuclear energy production is the fact that a variety of new concepts will involve fuel kernels of different sizes and with compositions of different densities. Therefore, without a fundamental understanding the underlying phenomena of the spouted bed TRISO coater, a significant amount of effort is required for production of each type of particle with a significant risk of not meeting the specifications. This difficulty will significantly and negatively impact the applications of AGRs for power generation and cause further challenges to them as an alternative source of commercial energy production. Accordingly, the proposed work seeks to overcome such hurdles and advance the scale-up, design, and performance of TRISO fuel particle spouted bed coaters. The overall objectives of the proposed work are to advance the fundamental understanding of the hydrodynamics by systematically investigating the effect of design and operating variables, to evaluate the reported dimensionless groups as scaling factors, and to establish a reliable scale-up methodology for the TRISO fuel particle spouted bed coaters based on hydrodynamic similarity via advanced measurement and computational techniques. An additional objective is to develop an on-line non-invasive measurement technique based on gamma ray densitometry (i.e. Nuclear Gauge Densitometry) that can be installed and used for coater process monitoring to ensure proper performance and operation and to facilitate the developed scale-up methodology. To achieve the objectives set for the project, the work will use optical probes and gamma ray computed tomography (CT) (for the measurements of solids/voidage holdup cross-sectional distribution and radial profiles along the bed height, spouted diameter, and fountain height) and radioactive particle tracking (RPT) (for the measurements of the 3D solids flow field, velocity, turbulent parameters, circulation time, solids lagrangian trajectories, and many other of spouted bed related hydrodynamic parameters). In addition, gas dynamic measurement techniques and pressure transducers will be utilized to complement the obtained information. The measurements obtained by these techniques will be used as benchmark data to evaluate and validate the computational fluid dynamic (CFD) models (two fluid model or discrete particle model) and their closures. The validated CFD models and closures will be used to facilitate the developed methodology for scale-up, design and hydrodynamic similarity. Successful execution of this work and the proposed tasks will advance the fundamental understanding of the coater flow field and quantify it for proper and safe design, scale-up, and performance. Such achievements will overcome the barriers to AGR applications and will help assure that the US maintains nuclear energy as a feasible option to meet the nation's needs for energy and environmental safety. In addition, the outcome of the proposed study will have a broader impact on other processes that utilize spouted beds, such as coal gasification, granulation, drying, catalytic reactions, etc.« less

A spherical harmonic approach for the determination of HCP texture from ultrasound: A solution to the inverse problem

NASA Astrophysics Data System (ADS)

Lan, Bo; Lowe, Michael J. S.; Dunne, Fionn P. E.

2015-10-01

A new spherical convolution approach has been presented which couples HCP single crystal wave speed (the kernel function) with polycrystal c-axis pole distribution function to give the resultant polycrystal wave speed response. The three functions have been expressed as spherical harmonic expansions thus enabling application of the de-convolution technique to enable any one of the three to be determined from knowledge of the other two. Hence, the forward problem of determination of polycrystal wave speed from knowledge of single crystal wave speed response and the polycrystal pole distribution has been solved for a broad range of experimentally representative HCP polycrystal textures. The technique provides near-perfect representation of the sensitivity of wave speed to polycrystal texture as well as quantitative prediction of polycrystal wave speed. More importantly, a solution to the inverse problem is presented in which texture, as a c-axis distribution function, is determined from knowledge of the kernel function and the polycrystal wave speed response. It has also been explained why it has been widely reported in the literature that only texture coefficients up to 4th degree may be obtained from ultrasonic measurements. Finally, the de-convolution approach presented provides the potential for the measurement of polycrystal texture from ultrasonic wave speed measurements.

Ytterbium coating of spherical Ni(OH) 2 cathode materials for Ni-MH batteries at elevated temperature

NASA Astrophysics Data System (ADS)

He, Xiangming; Wang, Li; Li, Wen; Jiang, Changyin; Wan, Chunrong

The Yb/Co coated nickel hydroxides were prepared by precipitation of Yb(OH) 3 on the surface of spherical nickel hydroxide, followed by precipitation of Co(OH) 2 on its surface. The optimum coating content of ytterbium was around 2% (atomic concentration) to obtain high discharge capacity at 60 °C. It was shown that the discharge capacity of nickel hydroxide at high temperatures was improved by coating of ytterbium and cobalt hydroxide. The high temperature performances of the sealed AAA-sized Ni-MH batteries using Yb/Co coated nickel hydroxide as positive electrodes were carried out, showing much better than those using the un-coated and only Co(OH) 2 coated nickel hydroxide electrodes. The charge acceptance of the battery using 2% Yb and 2% Co coated nickel hydroxide reached 92% at 60 °C, where the charge acceptances for the un-coated and only cobalt coated ones were only 42 and 46%, respectively. It has shown that the Yb/Co coating is an effective way to improve the high temperature performance of nickel hydroxide for nickel-metal hydride batteries.

Improving Genomic Prediction in Cassava Field Experiments Using Spatial Analysis.

PubMed

Elias, Ani A; Rabbi, Ismail; Kulakow, Peter; Jannink, Jean-Luc

2018-01-04

Cassava ( Manihot esculenta Crantz) is an important staple food in sub-Saharan Africa. Breeding experiments were conducted at the International Institute of Tropical Agriculture in cassava to select elite parents. Taking into account the heterogeneity in the field while evaluating these trials can increase the accuracy in estimation of breeding values. We used an exploratory approach using the parametric spatial kernels Power, Spherical, and Gaussian to determine the best kernel for a given scenario. The spatial kernel was fit simultaneously with a genomic kernel in a genomic selection model. Predictability of these models was tested through a 10-fold cross-validation method repeated five times. The best model was chosen as the one with the lowest prediction root mean squared error compared to that of the base model having no spatial kernel. Results from our real and simulated data studies indicated that predictability can be increased by accounting for spatial variation irrespective of the heritability of the trait. In real data scenarios we observed that the accuracy can be increased by a median value of 3.4%. Through simulations, we showed that a 21% increase in accuracy can be achieved. We also found that Range (row) directional spatial kernels, mostly Gaussian, explained the spatial variance in 71% of the scenarios when spatial correlation was significant. Copyright © 2018 Elias et al.

Effects of surface coating of Y(OH) 3 on the electrochemical performance of spherical Ni(OH) 2

NASA Astrophysics Data System (ADS)

Fan, Jing; Yang, Yifu; Yu, Peng; Chen, Weihua; Shao, Huixia

The effects of surface coating of Y(OH) 3 on the electrochemical performance of spherical Ni(OH) 2 were studied by cyclic voltammetry (CV) with soft-embedded electrode (SE-E). The coating was performed by chemical surface precipitation under different conditions. The structure, morphology, chemical composition and electrochemical properties of two different samples with surface coating of Y(OH) 3 were characterized and compared. The results show that a two-step oxidation process exists in the oxidation procedure of spherical Ni(OH) 2 corresponding to the formation of Ni(III) and Ni(IV), respectively. The conversion of Ni(III) to Ni(IV) is regarded as a side reaction in which Ni(IV) species is not stable. The presence of Y(OH) 3 on the particle surface can restrain the side reactions, especially the formation of Ni(IV). The application of coated Ni(OH) 2 to sealed Ni-MH batteries yielded a charge acceptance of about 88% at 60 °C. The results manifest that the high-temperature performance of Ni(OH) 2 electrode is related to the distribution of the adding elements in surface oxide layer of Ni(OH) 2, the sample with dense and porous coating surface, larger relative surface content and higher utilization ratio of yttrium is more effective.

TURBULENCE-INDUCED RELATIVE VELOCITY OF DUST PARTICLES. IV. THE COLLISION KERNEL

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

Pan, Liubin; Padoan, Paolo, E-mail: lpan@cfa.harvard.edu, E-mail: ppadoan@icc.ub.edu

Motivated by its importance for modeling dust particle growth in protoplanetary disks, we study turbulence-induced collision statistics of inertial particles as a function of the particle friction time, τ{sub p}. We show that turbulent clustering significantly enhances the collision rate for particles of similar sizes with τ{sub p} corresponding to the inertial range of the flow. If the friction time, τ{sub p,} {sub h}, of the larger particle is in the inertial range, the collision kernel per unit cross section increases with increasing friction time, τ{sub p,} {sub l}, of the smaller particle and reaches the maximum at τ{sub p,}more » {sub l} = τ{sub p,} {sub h}, where the clustering effect peaks. This feature is not captured by the commonly used kernel formula, which neglects the effect of clustering. We argue that turbulent clustering helps alleviate the bouncing barrier problem for planetesimal formation. We also investigate the collision velocity statistics using a collision-rate weighting factor to account for higher collision frequency for particle pairs with larger relative velocity. For τ{sub p,} {sub h} in the inertial range, the rms relative velocity with collision-rate weighting is found to be invariant with τ{sub p,} {sub l} and scales with τ{sub p,} {sub h} roughly as ∝ τ{sub p,h}{sup 1/2}. The weighting factor favors collisions with larger relative velocity, and including it leads to more destructive and less sticking collisions. We compare two collision kernel formulations based on spherical and cylindrical geometries. The two formulations give consistent results for the collision rate and the collision-rate weighted statistics, except that the spherical formulation predicts more head-on collisions than the cylindrical formulation.« less

Acceptance Test Data for the AGR-5/6/7 Irradiation Test Fuel Composite Defective IPyC Fraction and Pyrocarbon Anisotropy

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

Helmreich, Grant W.; Hunn, John D.; Skitt, Darren J.

Coated particle composite J52R-16-98005 was produced by Babcock and Wilcox Technologies (BWXT) as fuel for the Advanced Gas Reactor Fuel Development and Qualification (AGR) Program’s AGR-5/6/7 irradiation test in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR). This composite was comprised of four coated particle fuel batches J52O-16-93165B (26%), 93168B (26%), 93169B (24%), and 93170B (24%), chosen based on the Quality Control (QC) data acquired for each individual candidate AGR-5/6/7 batch. Each batch was coated in a 150-mm-diameter production-scale fluidized-bed chemical vapor deposition (CVD) furnace. Tristructural isotropic (TRISO) coatings were deposited on 425-μm-nominal-diameter spherical kernels from BWXT Lot J52R-16-69317more » containing a mixture of 15.5%-enriched uranium carbide and uranium oxide (UCO). The TRISO coatings consisted of four consecutive CVD layers: a ~50% dense carbon buffer layer with 100-μm-nominal thickness, a dense inner pyrolytic carbon (IPyC) layer with 40-μm-nominal thickness, a silicon carbide (SiC) layer with 35-μm-nominal thickness, and a dense outer pyrolytic carbon (OPyC) layer with 40-μm-nominal thickness. The TRISO-coated particle batches were sieved to upgrade the particles by removing over-sized and under-sized material, and the upgraded batches were designated by appending the letter A to the end of the batch number (e.g., 93165A). Secondary upgrading by sieving was performed on the A-designated batches to remove particles with missing or very-thin buffer layers that were identified during previous analysis of the individual batches for defective IPyC, as reported in the acceptance test data report for the AGR-5/6/7 production batches [Hunn et al. 2017]. The additionally-upgraded batches were designated by appending the letter B to the end of the batch number (e.g., 93165B).« less

Electron Microscopic Examination of Irradiated TRISO Coated Particles of Compact 6-3-2 of AGR-1 Experiment

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

Van Rooyen, Isabella Johanna; Demkowicz, Paul Andrew; Riesterer, Jessica Lori

2012-12-01

The electron microscopic examination of selected irradiated TRISO coated particles of the AGR-1 experiment of fuel compact 6-3-2 are presented in this report. Compact 6-3-2 refers to the compact in Capsule 6 at level 3 of Stack 2. The fuel used in capsule 6 compacts, are called the “baseline” fuel as it is fabricated with refined coating process conditions used to fabricate historic German fuel, because of its excellent irradiation performance with UO2 kernels. The AGR-1 fuel is however made of low-enriched uranium oxycarbide (UCO). Kernel diameters are approximately 350 µm with a U-235 enrichment of approximately 19.7%. Compact 6-3-2more » has been irradiated to 11.3% FIMA compact average burn-up with a time average, volume average temperature of 1070.2°C and with a compact average fast fluence of 2.38E21 n/cm« less

Electron Microscopic Examination of Irradiated TRISO Coated Particles of Compact 6-3-2 of AGR-1 Experiment

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

Van Rooyen, Isabella Johanna; Demkowicz, Paul Andrew; Riesterer, Jessica Lori

2012-12-01

The electron microscopic examination of selected irradiated TRISO coated particles of the AGR-1 experiment of fuel compact 6-3-2 are presented in this report. Compact 6-3-2 refers to the compact in Capsule 6 at level 3 of Stack 2. The fuel used in capsule 6 compacts, are called the “baseline” fuel as it is fabricated with refined coating process conditions used to fabricate historic German fuel, because of its excellent irradiation performance with UO 2 kernels. The AGR-1 fuel is however made of low-enriched uranium oxycarbide (UCO). Kernel diameters are approximately 350 µm with a U-235 enrichment of approximately 19.7%. Compactmore » 6-3-2 has been irradiated to 11.3% FIMA compact average burn-up with a time average, volume average temperature of 1070.2°C and with a compact average fast fluence of 2.38E21 n/cm« less

Surface engineering of low enriched uranium-molybdenum

NASA Astrophysics Data System (ADS)

Leenaers, A.; Van den Berghe, S.; Detavernier, C.

2013-09-01

Recent attempts to qualify the LEU(Mo) dispersion plate fuel with Si addition to the Al matrix up to high power and burn-up have not yet been successful due to unacceptable fuel plate swelling at a local burn-up above 60% 235U. The root cause of the failures is clearly related directly to the formation of the U(Mo)-Al(Si) interaction layer. Excessive formation of these layers around the fuel kernels severely weakens the local mechanical integrity and eventually leads to pillowing of the plate. In 2008, SCK·CEN has launched the SELENIUM U(Mo) dispersion fuel development project in an attempt to find an alternative way to reduce the interaction between U(Mo) fuel kernels and the Al matrix to a significantly low level: by applying a coating on the U(Mo) kernels. Two fuel plates containing 8gU/cc U(Mo) coated with respectively 600 nm Si and 1000 nm ZrN in a pure Al matrix were manufactured. These plates were irradiated in the BR2 reactor up to a maximum heat flux of 470 W/cm2 until a maximum local burn-up of approximately 70% 235U (˜50% plate average) was reached. Awaiting the PIE results, the advantages of applying a coating are discussed in this paper through annealing experiments and TRIM (the Transport of Ions in Matter) calculations.

Sol-gel preparation of hydrophobic silica antireflective coatings with low refractive index by base/acid two-step catalysis.

PubMed

Cai, Shuang; Zhang, Yulu; Zhang, Hongli; Yan, Hongwei; Lv, Haibing; Jiang, Bo

2014-07-23

Hydrophobic antireflective coatings with a low refractive index were prepared via a base/acid-catalyzed two-step sol-gel process using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors, respectively. The base-catalyzed hydrolysis of TEOS leads to the formation of a sol with spherical silica particles in the first step. In the second step, the acid-catalyzed MTES hydrolysis and condensation occur at the surface of the initial base-catalyzed spherical silica particles, which enlarge the silica particle size from 12.9 to 35.0 nm. By a dip-coating process, this hybrid sol gives an antireflective coating with a refractive index of about 1.15. Moreover, the water contact angles of the resulted coatings increase from 22.4 to 108.7° with the increases of MTES content, which affords the coatings an excellent hydrophobicity. A "core-shell" particle growth mechanism of the hybrid sol was proposed and the relationship between the microstructure of silica sols and the properties of AR coatings was investigated.

Spherical Tensor Calculus for Local Adaptive Filtering

NASA Astrophysics Data System (ADS)

Reisert, Marco; Burkhardt, Hans

In 3D image processing tensors play an important role. While rank-1 and rank-2 tensors are well understood and commonly used, higher rank tensors are rare. This is probably due to their cumbersome rotation behavior which prevents a computationally efficient use. In this chapter we want to introduce the notion of a spherical tensor which is based on the irreducible representations of the 3D rotation group. In fact, any ordinary cartesian tensor can be decomposed into a sum of spherical tensors, while each spherical tensor has a quite simple rotation behavior. We introduce so called tensorial harmonics that provide an orthogonal basis for spherical tensor fields of any rank. It is just a generalization of the well known spherical harmonics. Additionally we propose a spherical derivative which connects spherical tensor fields of different degree by differentiation. Based on the proposed theory we present two applications. We propose an efficient algorithm for dense tensor voting in 3D, which makes use of tensorial harmonics decomposition of the tensor-valued voting field. In this way it is possible to perform tensor voting by linear-combinations of convolutions in an efficient way. Secondly, we propose an anisotropic smoothing filter that uses a local shape and orientation adaptive filter kernel which can be computed efficiently by the use spherical derivatives.

Carbothermic synthesis of 820 μm uranium nitride kernels: Literature review, thermodynamics, analysis, and related experiments

NASA Astrophysics Data System (ADS)

Lindemer, T. B.; Voit, S. L.; Silva, C. M.; Besmann, T. M.; Hunt, R. D.

2014-05-01

The US Department of Energy is developing a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with uranium nitride (UN) kernels with diameters near 825 μm. This effort explores factors involved in the conversion of uranium oxide-carbon microspheres into UN kernels. An analysis of previous studies with sufficient experimental details is provided. Thermodynamic calculations were made to predict pressures of carbon monoxide and other relevant gases for several reactions that can be involved in the conversion of uranium oxides and carbides into UN. Uranium oxide-carbon microspheres were heated in a microbalance with an attached mass spectrometer to determine details of calcining and carbothermic conversion in argon, nitrogen, and vacuum. A model was derived from experiments on the vacuum conversion to uranium oxide-carbide kernels. UN-containing kernels were fabricated using this vacuum conversion as part of the overall process. Carbonitride kernels of ∼89% of theoretical density were produced along with several observations concerning the different stages of the process.

7 CFR 51.2763 - Damage.

Code of Federal Regulations, 2010 CFR

2010-01-01

... cuts, web or frass; (d) Freezing injury causing hard, translucent or discolored flesh; and, (e) Dirt when the surface of the kernel is heavily smeared, thickly flecked or coated with dirt, seriously...

Effects of coating spherical iron oxide nanoparticles

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

Milosevic, Irena; Motte, Laurence; Aoun, Bachir

2017-01-01

We investigate the effect of several coatings applied in biomedical applications to iron oxide nanoparticles on the size, structure and composition of the particles. The four structural techniques employed - TEM, DLS, VSM, SAXS and EXAFS - show no significant effects of the coatings on the spherical shape of the bare nanoparticles, the average sizes or the local order around the Fe atoms. The NPs coated with hydroxylmethylene bisphosphonate or catechol have a lower proportion of magnetite than the bare and citrated ones, raising the question whether the former are responsible for increasing the valence state of the oxide onmore » the NP surfaces and lowering the overall proportion of magnetite in the particles. VSM measurements show that these two coatings lead to a slightly higher saturation magnetization than the citrate. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazu and Dr. Federica Migliardo.« less

7 CFR 51.2721 - Damage.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., web or frass; (d) Freezing injury causing hard, translucent or discolored flesh; and (e) Dirt when the surface of the kernel is heavily smeared, thickly flecked or coated with dirt, seriously affecting its...

Background field removal technique based on non-regularized variable kernels sophisticated harmonic artifact reduction for phase data for quantitative susceptibility mapping.

PubMed

Kan, Hirohito; Arai, Nobuyuki; Takizawa, Masahiro; Omori, Kazuyoshi; Kasai, Harumasa; Kunitomo, Hiroshi; Hirose, Yasujiro; Shibamoto, Yuta

2018-06-11

We developed a non-regularized, variable kernel, sophisticated harmonic artifact reduction for phase data (NR-VSHARP) method to accurately estimate local tissue fields without regularization for quantitative susceptibility mapping (QSM). We then used a digital brain phantom to evaluate the accuracy of the NR-VSHARP method, and compared it with the VSHARP and iterative spherical mean value (iSMV) methods through in vivo human brain experiments. Our proposed NR-VSHARP method, which uses variable spherical mean value (SMV) kernels, minimizes L2 norms only within the volume of interest to reduce phase errors and save cortical information without regularization. In a numerical phantom study, relative local field and susceptibility map errors were determined using NR-VSHARP, VSHARP, and iSMV. Additionally, various background field elimination methods were used to image the human brain. In a numerical phantom study, the use of NR-VSHARP considerably reduced the relative local field and susceptibility map errors throughout a digital whole brain phantom, compared with VSHARP and iSMV. In the in vivo experiment, the NR-VSHARP-estimated local field could sufficiently achieve minimal boundary losses and phase error suppression throughout the brain. Moreover, the susceptibility map generated using NR-VSHARP minimized the occurrence of streaking artifacts caused by insufficient background field removal. Our proposed NR-VSHARP method yields minimal boundary losses and highly precise phase data. Our results suggest that this technique may facilitate high-quality QSM. Copyright © 2017. Published by Elsevier Inc.

Carbothermic Synthesis of 820 m UN Kernels: Literature Review, Thermodynamics, Analysis, and Related Experiments

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

Lindemer, Terrence; Voit, Stewart L; Silva, Chinthaka M

2014-01-01

The U.S. Department of Energy is considering a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with large, dense uranium nitride (UN) kernels. This effort explores many factors involved in using gel-derived uranium oxide-carbon microspheres to make large UN kernels. Analysis of recent studies with sufficient experimental details is provided. Extensive thermodynamic calculations are used to predict carbon monoxide and other pressures for several different reactions that may be involved in conversion of uranium oxides and carbides to UN. Experimentally, the method for making themore » gel-derived microspheres is described. These were used in a microbalance with an attached mass spectrometer to determine details of carbothermic conversion in argon, nitrogen, or vacuum. A quantitative model is derived from experiments for vacuum conversion to an uranium oxide-carbide kernel.« less

Antidiabetic and antioxidant functionality associated with phenolic constituents from fruit parts of indigenous black jamun (Syzygium cumini L.) landraces.

PubMed

Gajera, H P; Gevariya, Shila N; Hirpara, Darshna G; Patel, S V; Golakiya, B A

2017-09-01

Fruit phenolics are important dietary antioxidant and antidiabetic constituents. The fruit parts (pulp, seed, seed coat, kernel) of underutilized indigenous six black jamun landraces ( Syzygium cumini L.), found in Gir forest region of India and differed in their fruit size, shape and weight, are evaluated and correlated with antidiabetic, DPPH radical scavenging and phenolic constituents. The α-amylase inhibitors propose an efficient antidiabetic strategy and the levels of postprandial hyperglycemia were lowered by restraining starch breakdown. The sequential solvent systems with ascending polarity-petroleum ether, ethyl acetate, methanol and water were performed for soxhlet extraction by hot percolation method and extractive yield was found maximum with methanolic fruit part extracts of six landraces. The methanolic extracts of fruit parts also evidenced higher antidiabetic activity and hence utilized for further characterization. Among the six landraces, pulp and kernel of BJLR-6 (very small, oblong fruits) evidenced maximum 53.8 and 98.2% inhibition of α-amylase activity, respectively. The seed attained inhibitory activity mostly contributed by the kernel fraction. The inhibition of DPPH radical scavenging activity was positively correlated with phenol constituents. An HPLC-PDA technique was used to quantify the seven individual phenolics. The seed and kernel of BJLR-6 exhibited higher individual phenolics-gallic, catechin, ellagic, ferulic acids and quercetin, whereas pulp evidenced higher with gallic acid and catechin as α-amylase inhibitors. The IC 50 value indicates concentration of fruit extracts exhibiting ≥50% inhibition on porcine pancreatic α-amylase (PPA) activity. The kernel fraction of BJLR6 evidenced lowest (8.3 µg ml -1 ) IC 50 value followed by seed (12.9 µg ml -1 ), seed coat (50.8 µg ml -1 ) and pulp (270 µg ml -1 ). The seed and kernel of BJLR-6 inhibited PPA at much lower concentrations than standard acarbose (24.7 µg ml -1 ) considering good candidates for antidiabetic herbal formulations.

Monostatic lidar/radar invisibility using coated spheres.

PubMed

Zhai, Peng-Wang; You, Yu; Kattawar, George W; Yang, Ping

2008-02-04

The Lorenz-Mie theory is revisited to explicitly include materials whose permeability is different from unity. The expansion coefficients of the scattered field are given for light scattering by both homogeneous and coated spheres. It is shown that the backscatter is exactly zero if the impedance of the spherical particles is equal to the intrinsic impedance of the surrounding medium. If spherical particles are sufficiently large, the zero backscatter can be explained as impedance matching using the asymptotic expression for the radar backscattering cross section. In the case of a coated sphere, the shell can be regarded as a cloak if the product of the thickness and the imaginary part of the refractive index of the outer shell is large.

Receiving sensitivity and transmitting voltage response of a fluid loaded spherical piezoelectric transducer with an elastic coating.

PubMed

George, Jineesh; Ebenezer, D D; Bhattacharyya, S K

2010-10-01

A method is presented to determine the response of a spherical acoustic transducer that consists of a fluid-filled piezoelectric sphere with an elastic coating embedded in infinite fluid to electrical and plane-wave acoustic excitations. The exact spherically symmetric, linear, differential, governing equations are used for the interior and exterior fluids, and elastic and piezoelectric materials. Under acoustic excitation and open circuit boundary condition, the equation governing the piezoelectric sphere is homogeneous and the solution is expressed in terms of Bessel functions. Under electrical excitation, the equation governing the piezoelectric sphere is inhomogeneous and the complementary solution is expressed in terms of Bessel functions and the particular integral is expressed in terms of a power series. Numerical results are presented to illustrate the effect of dimensions of the piezoelectric sphere, fluid loading, elastic coating and internal material losses on the open-circuit receiving sensitivity and transmitting voltage response of the transducer.

Whispering gallery modes in a spherical microcavity with a photoluminescent shell

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

Grudinkin, S. A., E-mail: grudink@gvg.ioffe.ru; Dontsov, A. A.; Feoktistov, N. A.

2015-10-15

Whispering-gallery mode spectra in optical microcavities based on spherical silica particles coated with a thin photoluminescent shell of hydrogenated amorphous silicon carbide are studied. The spectral positions of the whispering-gallery modes for spherical microcavities with a shell are calculated. The dependence of the spectral distance between the TE and TM modes on the shell thickness is examined.

Progress in understanding fission-product behaviour in coated uranium-dioxide fuel particles

NASA Astrophysics Data System (ADS)

Barrachin, M.; Dubourg, R.; Kissane, M. P.; Ozrin, V.

2009-03-01

Supported by results of calculations performed with two analytical tools (MFPR, which takes account of physical and chemical mechanisms in calculating the chemical forms and physical locations of fission products in UO2, and MEPHISTA, a thermodynamic database), this paper presents an investigation of some important aspects of the fuel microstructure and chemical evolutions of irradiated TRISO particles. The following main conclusions can be identified with respect to irradiated TRISO fuel: first, the relatively low oxygen potential within the fuel particles with respect to PWR fuel leads to chemical speciation that is not typical of PWR fuels, e.g., the relatively volatile behaviour of barium; secondly, the safety-critical fission-product caesium is released from the urania kernel but the buffer and pyrolytic-carbon coatings could form an important chemical barrier to further migration (i.e., formation of carbides). Finally, significant releases of fission gases from the urania kernel are expected even in nominal conditions.

Anisotropic biodegradable lipid coated particles for spatially dynamic protein presentation.

PubMed

Meyer, Randall A; Mathew, Mohit P; Ben-Akiva, Elana; Sunshine, Joel C; Shmueli, Ron B; Ren, Qiuyin; Yarema, Kevin J; Green, Jordan J

2018-05-01

There has been growing interest in the use of particles coated with lipids for applications ranging from drug delivery, gene delivery, and diagnostic imaging to immunoengineering. To date, almost all particles with lipid coatings have been spherical despite emerging evidence that non-spherical shapes can provide important advantages including reduced non-specific elimination and increased target-specific binding. We combine control of core particle geometry with control of particle surface functionality by developing anisotropic, biodegradable ellipsoidal particles with lipid coatings. We demonstrate that these lipid coated ellipsoidal particles maintain advantageous properties of lipid polymer hybrid particles, such as the ability for modular protein conjugation to the particle surface using versatile bioorthogonal ligation reactions. In addition, they exhibit biomimetic membrane fluidity and demonstrate lateral diffusive properties characteristic of natural membrane proteins. These ellipsoidal particles simultaneously provide benefits of non-spherical particles in terms of stability and resistance to non-specific phagocytosis by macrophages as well as enhanced targeted binding. These biomaterials provide a novel and flexible platform for numerous biomedical applications. The research reported here documents the ability of non-spherical polymeric particles to be coated with lipids to form anisotropic biomimetic particles. In addition, we demonstrate that these lipid-coated biodegradable polymeric particles can be conjugated to a wide variety of biological molecules in a "click-like" fashion. This is of interest due to the multiple types of cellular mimicry enabled by this biomaterial based technology. These features include mimicry of the highly anisotropic shape exhibited by cells, surface presentation of membrane bound protein mimetics, and lateral diffusivity of membrane bound substrates comparable to that of a plasma membrane. This platform is demonstrated to facilitate targeted cell binding while being resistant to non-specific cellular uptake. Such a platform could allow for investigations into how physical parameters of a particle and its surface affect the interface between biomaterials and cells, as well as provide biomimetic technology platforms for drug delivery and cellular engineering. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Selection and properties of alternative forming fluids for TRISO fuel kernel production

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

Baker, M. P.; King, J. C.; Gorman, B. P.

2013-01-01

Current Very High Temperature Reactor (VHTR) designs incorporate TRi-structural ISOtropic (TRISO) fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel using wet chemistry to produce uranium oxyhydroxide gel spheres by dropping a cold precursor solution into a hot column of trichloroethylene (TCE). Over time, gelation byproducts inhibit complete gelation, and the TCE must be purified or discarded. The resulting TCE waste stream contains both radioactive and hazardous materials and is thus considered a mixed hazardous waste. Changing the forming fluid to a non-hazardousmore » alternative could greatly improve the economics of TRISO fuel kernel production. Selection criteria for a replacement forming fluid narrowed a list of ~10,800 chemicals to yield ten potential replacement forming fluids: 1-bromododecane, 1- bromotetradecane, 1-bromoundecane, 1-chlorooctadecane, 1-chlorotetradecane, 1-iododecane, 1-iodododecane, 1-iodohexadecane, 1-iodooctadecane, and squalane. The density, viscosity, and surface tension for each potential replacement forming fluid were measured as a function of temperature between 25 °C and 80 °C. Calculated settling velocities and heat transfer rates give an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane show the greatest promise as replacements, and future tests will verify their ability to form satisfactory fuel kernels.« less

Selection and properties of alternative forming fluids for TRISO fuel kernel production

NASA Astrophysics Data System (ADS)

Baker, M. P.; King, J. C.; Gorman, B. P.; Marshall, D. W.

2013-01-01

Current Very High Temperature Reactor (VHTR) designs incorporate TRi-structural ISOtropic (TRISO) fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel using wet chemistry to produce uranium oxyhydroxide gel spheres by dropping a cold precursor solution into a hot column of trichloroethylene (TCE). Over time, gelation byproducts inhibit complete gelation, and the TCE must be purified or discarded. The resulting TCE waste stream contains both radioactive and hazardous materials and is thus considered a mixed hazardous waste. Changing the forming fluid to a non-hazardous alternative could greatly improve the economics of TRISO fuel kernel production. Selection criteria for a replacement forming fluid narrowed a list of ˜10,800 chemicals to yield ten potential replacement forming fluids: 1-bromododecane, 1-bromotetradecane, 1-bromoundecane, 1-chlorooctadecane, 1-chlorotetradecane, 1-iododecane, 1-iodododecane, 1-iodohexadecane, 1-iodooctadecane, and squalane. The density, viscosity, and surface tension for each potential replacement forming fluid were measured as a function of temperature between 25 °C and 80 °C. Calculated settling velocities and heat transfer rates give an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane show the greatest promise as replacements, and future tests will verify their ability to form satisfactory fuel kernels.

Application of SWIR hyperspectral imaging and chemometrics for identification of aflatoxin B1 contaminated maize kernels

NASA Astrophysics Data System (ADS)

Kimuli, Daniel; Wang, Wei; Wang, Wei; Jiang, Hongzhe; Zhao, Xin; Chu, Xuan

2018-03-01

A short-wave infrared (SWIR) hyperspectral imaging system (1000-2500 nm) combined with chemometric data analysis was used to detect aflatoxin B1 (AFB1) on surfaces of 600 kernels of four yellow maize varieties from different States of the USA (Georgia, Illinois, Indiana and Nebraska). For each variety, four AFB1 solutions (10, 20, 100 and 500 ppb) were artificially deposited on kernels and a control group was generated from kernels treated with methanol solution. Principal component analysis (PCA), partial least squares discriminant analysis (PLSDA) and factorial discriminant analysis (FDA) were applied to explore and classify maize kernels according to AFB1 contamination. PCA results revealed partial separation of control kernels from AFB1 contaminated kernels for each variety while no pattern of separation was observed among pooled samples. A combination of standard normal variate and first derivative pre-treatments produced the best PLSDA classification model with accuracy of 100% and 96% in calibration and validation, respectively, from Illinois variety. The best AFB1 classification results came from FDA on raw spectra with accuracy of 100% in calibration and validation for Illinois and Nebraska varieties. However, for both PLSDA and FDA models, poor AFB1 classification results were obtained for pooled samples relative to individual varieties. SWIR spectra combined with chemometrics and spectra pre-treatments showed the possibility of detecting maize kernels of different varieties coated with AFB1. The study further suggests that increase of maize kernel constituents like water, protein, starch and lipid in a pooled sample may have influence on detection accuracy of AFB1 contamination.

Experimental study of turbulent flame kernel propagation

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

Mansour, Mohy; Peters, Norbert; Schrader, Lars-Uve

2008-07-15

Flame kernels in spark ignited combustion systems dominate the flame propagation and combustion stability and performance. They are likely controlled by the spark energy, flow field and mixing field. The aim of the present work is to experimentally investigate the structure and propagation of the flame kernel in turbulent premixed methane flow using advanced laser-based techniques. The spark is generated using pulsed Nd:YAG laser with 20 mJ pulse energy in order to avoid the effect of the electrodes on the flame kernel structure and the variation of spark energy from shot-to-shot. Four flames have been investigated at equivalence ratios, {phi}{submore » j}, of 0.8 and 1.0 and jet velocities, U{sub j}, of 6 and 12 m/s. A combined two-dimensional Rayleigh and LIPF-OH technique has been applied. The flame kernel structure has been collected at several time intervals from the laser ignition between 10 {mu}s and 2 ms. The data show that the flame kernel structure starts with spherical shape and changes gradually to peanut-like, then to mushroom-like and finally disturbed by the turbulence. The mushroom-like structure lasts longer in the stoichiometric and slower jet velocity. The growth rate of the average flame kernel radius is divided into two linear relations; the first one during the first 100 {mu}s is almost three times faster than that at the later stage between 100 and 2000 {mu}s. The flame propagation is slightly faster in leaner flames. The trends of the flame propagation, flame radius, flame cross-sectional area and mean flame temperature are related to the jet velocity and equivalence ratio. The relations obtained in the present work allow the prediction of any of these parameters at different conditions. (author)« less

In-pile test results of U-silicide or U-nitride coated U-7Mo particle dispersion fuel in Al

NASA Astrophysics Data System (ADS)

Kim, Yeon Soo; Park, J. M.; Lee, K. H.; Yoo, B. O.; Ryu, H. J.; Ye, B.

2014-11-01

U-silicide or U-nitride coated U-Mo particle dispersion fuel in Al (U-Mo/Al) was in-pile tested to examine the effectiveness of the coating as a diffusion barrier between the U-7Mo fuel kernels and Al matrix. This paper reports the PIE data and analyses focusing on the effectiveness of the coating in terms of interaction layer (IL) growth and general fuel performance. The U-silicide coating showed considerable success, but it also provided evidence for additional improvement for coating process. The U-nitride coated specimen showed largely inefficient results in reducing IL growth. From the test, important observations were also made that can be utilized to improve U-Mo/Al fuel performance. The heating process for coating turned out to be beneficial to suppress fuel swelling. The use of larger fuel particles confirmed favorable effects on fuel performance.

Calculation of the acoustic radiation force on coated spherical shells in progressive and standing plane waves.

PubMed

Mitri, F G

2006-07-01

In this paper, analytical equations are derived for the time-averaged radiation force induced by progressive and standing acoustic waves incident on elastic spherical shells covered with a layer of viscoelastic and sound-absorbing material. The fluid surrounding the shells is considered compressible and nonviscous. The incident field is assumed to be moderate so that the scattered field from the shells is taken to linear approximation. The analytical results are illustrated by means of a numerical example in which the radiation force function curves are displayed, with particular emphasis on the coating thickness and the content of the hollow region of the shells. The fluid-loading on the radiation force function curves is analysed as well. This study attempts to generalize the various treatments of radiation force due to both progressive and standing waves on spherically-shaped structures immersed in ideal fluids. The results show that various ways can be effectively used for damping resonance peaks, such as by changing the fluid in the interior hollow region of the shells or by changing the coating thickness.

Determining the minimum required uranium carbide content for HTGR UCO fuel kernels

DOE PAGES

McMurray, Jacob W.; Lindemer, Terrence B.; Brown, Nicholas R.; ...

2017-03-10

There are three important failure mechanisms that must be controlled in high-temperature gas-cooled reactor (HTGR) fuel for certain higher burnup applications are SiC layer rupture, SiC corrosion by CO, and coating compromise from kernel migration. All are related to high CO pressures stemming from free O generated when uranium present as UO 2 fissions and the O is not subsequently bound by other elements. Furthermore, in the HTGR UCO kernel design, CO buildup from excess O is controlled by the inclusion of additional uranium in the form of a carbide, UC x. An approach for determining the minimum UC xmore » content to ensure negligible CO formation was developed and demonstrated using CALPHAD models and the Serpent 2 reactor physics and depletion analysis tool. Our results are intended to be more accurate than previous estimates by including more nuclear and chemical factors, in particular the effect of transmutation products on the oxygen distribution as the fuel kernel composition evolves with burnup.« less

Development of a Radial Deconsolidation Method

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

Helmreich, Grant W.; Montgomery, Fred C.; Hunn, John D.

2015-12-01

A series of experiments have been initiated to determine the retention or mobility of fission products* in AGR fuel compacts [Petti, et al. 2010]. This information is needed to refine fission product transport models. The AGR-3/4 irradiation test involved half-inch-long compacts that each contained twenty designed-to-fail (DTF) particles, with 20-μm thick carbon-coated kernels whose coatings were deliberately fabricated such that they would crack under irradiation, providing a known source of post-irradiation isotopes. The DTF particles in these compacts were axially distributed along the compact centerline so that the diffusion of fission products released from the DTF kernels would be radiallymore » symmetric [Hunn, et al. 2012; Hunn et al. 2011; Kercher, et al. 2011; Hunn, et al. 2007]. Compacts containing DTF particles were irradiated at Idaho National Laboratory (INL) at the Advanced Test Reactor (ATR) [Collin, 2015]. Analysis of the diffusion of these various post-irradiation isotopes through the compact requires a method to radially deconsolidate the compacts so that nested-annular volumes may be analyzed for post-irradiation isotope inventory in the compact matrix, TRISO outer pyrolytic carbon (OPyC), and DTF kernels. An effective radial deconsolidation method and apparatus appropriate to this application has been developed and parametrically characterized.« less

Solutions for the conductivity of multi-coated spheres and spherically symmetric inclusion problems

NASA Astrophysics Data System (ADS)

Pham, Duc Chinh

2018-02-01

Variational results on the macroscopic conductivity (thermal, electrical, etc.) of the multi-coated sphere assemblage have been used to derive the explicit expression of the respective field (thermal, electrical, etc.) within the spheres in d dimensions (d=2,3). A differential substitution approach has been developed to construct various explicit expressions or determining equations for the effective spherically symmetric inclusion problems, which include those with radially variable conductivity, different radially variable transverse and normal conductivities, and those involving imperfect interfaces, in d dimensions. When the volume proportion of the outermost spherical shell increases toward 1, one obtains the respective exact results for the most important specific cases: the dilute solutions for the compound inhomogeneities suspended in a major matrix phase. Those dilute solution results are also needed for other effective medium approximation schemes.

Plasmonic and silicon spherical nanoparticle antireflective coatings

NASA Astrophysics Data System (ADS)

Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

2016-03-01

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

Plasmonic and silicon spherical nanoparticle antireflective coatings

PubMed Central

Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

2016-01-01

Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

Understanding the effects of process parameters on the properties of cold gas dynamic sprayed pure titanium coatings

NASA Astrophysics Data System (ADS)

Wong, Wilson

The cold gas dynamic spraying of commercially pure titanium coatings was investigated. Specifically, the relationship between several key cold spray parameters on the quality of the resulting coatings was studied in order to gain a more thorough understanding of the cold spray process. To achieve this goal, three distinct investigations were performed. The first part of the investigation focussed on the effect of propelling gas, particularly helium and nitrogen, during the cold spraying of titanium coatings. Coatings were characterised by SEM and were evaluated for their deposition efficiency (DE), microhardness, and porosity. In selected conditions, three particle velocities were investigated such that for each condition, the propelling gasses temperature and pressure were attuned to attain similar particle velocities for each gas. In addition, a thick and fully dense cold sprayed titanium coating was achieved with optimised spray parameters and nozzle using helium. The corresponding average particle velocity was 1173 m/s. The second part of the investigation studied the effect of particle morphology (spherical, sponge, and irregular) and size distributions (mean particle sizes of 20, 29, and 36 mum) of commercially pure titanium on the mechanical properties of the resulting cold sprayed coatings. Numerous powder and coating characterisations were performed. From these data, semi-empirical flow (stress-strain) curves were generated based on the Johnson-Cook plasticity model which could be used as a measure of cold sprayability. Cold sprayability can be defined as the ease with which a powder can be cold sprayed. It was found that the sponge and irregular commercially pure titanium powders had higher oxygen content, poorer powder flowability, higher compression ratio, lower powder packing factor, and higher average particle impact velocities compared to the spherical powders. XRD results showed no new phases present when comparing the various feedstock powders to their corresponding coatings. For all feedstock powder morphologies, it was observed that the larger the particle size, the higher the temperature generated on impact. For the spherical powders, the higher the temperature generated on impact, the lower the stress needed to deform the particle. In addition, as the kinetic energy of the impacting particle increased, the flow peak stress decreased while the final strain increased. Furthermore, higher final flow strains were associated with higher coating DeltaHV 10 (between the coatings and the feedstock powders). Similar relationships are expected to exist for the sponge and irregular feedstock powders. Based on porosity, the spherical medium powder was found to have the best cold sprayability. The final part of the investigation focussed on the effect of substrate surface roughness and coating thickness on the adhesion strength of commercially pure titanium cold sprayed coatings onto Steel 1020, Al 6061, and Ti substrates. Adhesion strength was measured by tensile/pull tests according to ASTM C-633-01 standard. Through-thickness residual stresses of selected coatings were measured using the modified layer removal method (MLRM). In addition, mean coating residual stresses were calculated from MLRM results. It was found that adhesion strength increases with increasing substrate surface roughness and decreases with increasing coating thickness. Furthermore, mean coating residual stresses were correlated with adhesion strength and it was suggested that higher adhesion strengths are associated with higher mean compressive stresses and a higher probability for adiabatic shear instability to occur due to the higher particle impact velocities. In general, it was found that under similar cold spray conditions and substrate surface preparation method, adhesion strength was strongest for commercially pure titanium coatings deposited onto Al 6061, followed by Ti, then Steel 1020.

Tumour control probability derived from dose distribution in homogeneous and heterogeneous models: assuming similar pharmacokinetics, 125Sn-177Lu is superior to 90Y-177Lu in peptide receptor radiotherapy

NASA Astrophysics Data System (ADS)

Walrand, Stephan; Hanin, François-Xavier; Pauwels, Stanislas; Jamar, François

2012-07-01

Clinical trials on 177Lu-90Y therapy used empirical activity ratios. Radionuclides (RN) with larger beta maximal range could favourably replace 90Y. Our aim is to provide RN dose-deposition kernels and to compare the tumour control probability (TCP) of RN combinations. Dose kernels were derived by integration of the mono-energetic beta-ray dose distributions (computed using Monte Carlo) weighted by their respective beta spectrum. Nine homogeneous spherical tumours (1-25 mm in diameter) and four spherical tumours including a lattice of cold, but alive, spheres (1, 3, 5, 7 mm in diameter) were modelled. The TCP for 93Y, 90Y and 125Sn in combination with 177Lu in variable proportions (that kept constant the renal cortex biological effective dose) were derived by 3D dose kernel convolution. For a mean tumour-absorbed dose of 180 Gy, 2 mm homogeneous tumours and tumours including 3 mm diameter cold alive spheres were both well controlled (TCP > 0.9) using a 75-25% combination of 177Lu and 90Y activity. However, 125Sn-177Lu achieved a significantly better result by controlling 1 mm-homogeneous tumour simultaneously with tumours including 5 mm diameter cold alive spheres. Clinical trials using RN combinations should use RN proportions tuned to the patient dosimetry. 125Sn production and its coupling to somatostatin analogue appear feasible. Assuming similar pharmacokinetics 125Sn is the best RN for combination with 177Lu in peptide receptor radiotherapy justifying pharmacokinetics studies in rodent of 125Sn-labelled somatostatin analogues.

Effect of different methods of preliminary surface treatment and magnetron sputtering on the adhesion of Si coatings

NASA Astrophysics Data System (ADS)

Borisov, D. P.; Slabodchikov, V. A.; Kuznetsov, V. M.

2017-05-01

The paper presents research results on the adhesion of Si coatings deposited by magnetron sputtering on NiTi substrates after preliminary surface treatment (cleaning and activation) with low-energy ion beams and gas discharge plasma. The adhesion properties of the coatings obtained by two methods are analyzed and compared using data of scratch and spherical abrasion tests.

A novel approach to a fine particle coating using porous spherical silica as core particles.

PubMed

Ishida, Makoto; Uchiyama, Jumpei; Isaji, Keiko; Suzuki, Yuta; Ikematsu, Yasuyuki; Aoki, Shigeru

2014-08-01

Abstract The applicability of porous spherical silica (PSS) was evaluated as core particles for pharmaceutical products by comparing it with commercial core particles such as mannitol (NP-108), sucrose and microcrystalline cellulose spheres. We investigated the physical properties of core particles, such as particle size distribution, flow properties, crushing strength, plastic limit, drying rate, hygroscopic property and aggregation degree. It was found that PSS was a core particle of small particle size, low friability, high water adsorption capacity, rapid drying rate and lower occurrence of particle aggregation, although wettability is a factor to be carefully considered. The aggregation and taste-masking ability using PSS and NP-108 as core particles were evaluated at a fluidized-bed coating process. The functional coating under the excess spray rate shows different aggregation trends and dissolution profiles between PSS and NP-108; thereby, exhibiting the formation of uniform coating under the excess spray rate in the case of PSS. This expands the range of the acceptable spray feed rates to coat fine particles, and indicates the possibility of decreasing the coating time. The results obtained in this study suggested that the core particle, which has a property like that of PSS, was useful in overcoming such disadvantages as large particle size, which feels gritty in oral cavity; particle aggregation; and the long coating time of the particle coating process. These results will enable the practical fine particle coating method by increasing the range of optimum coating conditions and decreasing the coating time in fluidized bed technology.

Quantifying the sensitivity of post-glacial sea level change to laterally varying viscosity

NASA Astrophysics Data System (ADS)

Crawford, Ophelia; Al-Attar, David; Tromp, Jeroen; Mitrovica, Jerry X.; Austermann, Jacqueline; Lau, Harriet C. P.

2018-05-01

We present a method for calculating the derivatives of measurements of glacial isostatic adjustment (GIA) with respect to the viscosity structure of the Earth and the ice sheet history. These derivatives, or kernels, quantify the linearised sensitivity of measurements to the underlying model parameters. The adjoint method is used to enable efficient calculation of theoretically exact sensitivity kernels within laterally heterogeneous earth models that can have a range of linear or non-linear viscoelastic rheologies. We first present a new approach to calculate GIA in the time domain, which, in contrast to the more usual formulation in the Laplace domain, is well suited to continuously varying earth models and to the use of the adjoint method. Benchmarking results show excellent agreement between our formulation and previous methods. We illustrate the potential applications of the kernels calculated in this way through a range of numerical calculations relative to a spherically symmetric background model. The complex spatial patterns of the sensitivities are not intuitive, and this is the first time that such effects are quantified in an efficient and accurate manner.

[Intercellular relationship of notochord determination of Xenopus laevis].

PubMed

Zeng, M B; Zhou, M Y; Wang, Y

1995-09-01

During the process of determination, the presumptive notochord is situated beneath neuroepithelium, flanked at two sides by presumptive somites and underlain with archenteron roof ventrally. Among these neighbouring embryonic tissues, presumptive somites were found to exert the main influence on notochord determination. By electron microscopic observations, the presumptive notochord and somite cells were seen to situate either close to each other (plate I, Fig. 1) or connected by cytoplasmic processes forming intercellular lumen (plate I, Fig. 5). Coated pits and coated vesicles appeared at the outer surface of both types of cells (plate I, Figs. 1-4). For the presumptive somite cells, spherical bodies of different sizes and variable contents were observed either near or protruding from the outer surface (plate II, Figs. 6-10). The spherical bodies were also found in the intercellular lumen (plate III, Fig. 11). These spherical bodies were mainly composed of granules, loosely scattered or densely packed. The granules were of similar size and similar shade of electron staining as those of ribosomes of the presumptive somite cells. For the presumptive notochord cells, no spherical bodies of the above mentioned type were found, but phenomenon of engulfing luminal material was observed (plate III, Fig. 12). The significance of the appearance of these spherical bodies in the determination of notochord cells has been discussed.

Preparation of Simulated LBL Defects for Round Robin Experiment

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

Gerczak, Tyler J.; Baldwin, Charles A.; Hunn, John D.

2016-01-01

A critical characteristic of the TRISO fuel design is its ability to retain fission products. During reactor operation, the TRISO layers act as barriers to release of fission products not stabilized in the kernel. Each component of the TRISO particle and compact construction plays a unique role in retaining select fission products, and layer performance is often interrelated. The IPyC, SiC, and OPyC layers are barriers to the release of fission product gases such as Kr and Xe. The SiC layer provides the primary barrier to release of metallic fission products not retained in the kernel, as transport across themore » SiC layer is rate limiting due to the greater permeability of the IPyC and OPyC layers to many metallic fission products. These attributes allow intact TRISO coatings to successfully retain most fission products released from the kernel, with the majority of released fission products during operation being due to defective, damaged, or failed coatings. This dominant release of fission products from compromised particles contributes to the overall source term in reactor; causing safety and maintenance concerns and limiting the lifetime of the fuel. Under these considerations, an understanding of the nature and frequency of compromised particles is an important part of predicting the expected fission product release and ensuring safe and efficient operation.« less

Sensitivity kernels for viscoelastic loading based on adjoint methods

NASA Astrophysics Data System (ADS)

Al-Attar, David; Tromp, Jeroen

2014-01-01

Observations of glacial isostatic adjustment (GIA) allow for inferences to be made about mantle viscosity, ice sheet history and other related parameters. Typically, this inverse problem can be formulated as minimizing the misfit between the given observations and a corresponding set of synthetic data. When the number of parameters is large, solution of such optimization problems can be computationally challenging. A practical, albeit non-ideal, solution is to use gradient-based optimization. Although the gradient of the misfit required in such methods could be calculated approximately using finite differences, the necessary computation time grows linearly with the number of model parameters, and so this is often infeasible. A far better approach is to apply the `adjoint method', which allows the exact gradient to be calculated from a single solution of the forward problem, along with one solution of the associated adjoint problem. As a first step towards applying the adjoint method to the GIA inverse problem, we consider its application to a simpler viscoelastic loading problem in which gravitationally self-consistent ocean loading is neglected. The earth model considered is non-rotating, self-gravitating, compressible, hydrostatically pre-stressed, laterally heterogeneous and possesses a Maxwell solid rheology. We determine adjoint equations and Fréchet kernels for this problem based on a Lagrange multiplier method. Given an objective functional J defined in terms of the surface deformation fields, we show that its first-order perturbation can be written δ J = int _{MS}K_{η }δ ln η dV +int _{t0}^{t1}int _{partial M}K_{dot{σ }} δ dot{σ } dS dt, where δ ln η = δη/η denotes relative viscosity variations in solid regions MS, dV is the volume element, δ dot{σ } is the perturbation to the time derivative of the surface load which is defined on the earth model's surface ∂M and for times [t0, t1] and dS is the surface element on ∂M. The `viscosity kernel' Kη determines the linearized sensitivity of J to viscosity perturbations defined with respect to a laterally heterogeneous reference earth model, while the `rate-of-loading kernel' K_{dot{σ }} determines the sensitivity to variations in the time derivative of the surface load. By restricting attention to spherically symmetric viscosity perturbations, we also obtain a `radial viscosity kernel' overline{K}_{η } such that the associated contribution to δJ can be written int _{IS}overline{K}_{η }δ ln η dr, where IS denotes the subset of radii lying in solid regions. In order to illustrate this theory, we describe its numerical implementation in the case of a spherically symmetric earth model using a 1-D spectral element method, and calculate sensitivity kernels for a range of realistic observables.

Spherical hashing: binary code embedding with hyperspheres.

PubMed

Heo, Jae-Pil; Lee, Youngwoon; He, Junfeng; Chang, Shih-Fu; Yoon, Sung-Eui

2015-11-01

Many binary code embedding schemes have been actively studied recently, since they can provide efficient similarity search, and compact data representations suitable for handling large scale image databases. Existing binary code embedding techniques encode high-dimensional data by using hyperplane-based hashing functions. In this paper we propose a novel hypersphere-based hashing function, spherical hashing, to map more spatially coherent data points into a binary code compared to hyperplane-based hashing functions. We also propose a new binary code distance function, spherical Hamming distance, tailored for our hypersphere-based binary coding scheme, and design an efficient iterative optimization process to achieve both balanced partitioning for each hash function and independence between hashing functions. Furthermore, we generalize spherical hashing to support various similarity measures defined by kernel functions. Our extensive experiments show that our spherical hashing technique significantly outperforms state-of-the-art techniques based on hyperplanes across various benchmarks with sizes ranging from one to 75 million of GIST, BoW and VLAD descriptors. The performance gains are consistent and large, up to 100 percent improvements over the second best method among tested methods. These results confirm the unique merits of using hyperspheres to encode proximity regions in high-dimensional spaces. Finally, our method is intuitive and easy to implement.

Spore formation in Myxococcus xanthus is tied to cytoskeleton functions and polysaccharide spore coat deposition

PubMed Central

Müller, Frank D.; Schink, Christian W.; Hoiczyk, Egbert; Cserti, Emöke; Higgs, Penelope I.

2011-01-01

Summary Myxococcus xanthus is a Gram-negative bacterium that differentiates into environmentally resistant spores. Spore differentiation involves septation-independent remodelling of the rod-shaped vegetative cell into a spherical spore and deposition of a thick and compact spore coat outside of the outer membrane. Our analyses suggest that spore coat polysaccharides are exported to the cell surface by the Exo outer membrane polysaccharide export/polysaccharide co-polymerase 2a (OPX/PCP-2a) machinery. Conversion of the capsule-like polysaccharide layer into a compact spore coat layer requires the Nfs proteins which likely form a complex in the cell envelope. Mutants in either nfs, exo, or two other genetic loci encoding homologs of polysaccharide synthesis enzymes, fail to complete morphogenesis from rods to spherical spores and instead produce a transient state of deformed cell morphology before reversion into typical rods. We additionally provide evidence that the cell cytoskeletal protein, MreB, plays an important role in rod to spore morphogenesis and for spore outgrowth. These studies provide evidence that this novel gram-negative differentiation process is tied to cytoskeleton functions and polysaccharide spore coat deposition. PMID:22188356

Wavelets on the Group SO(3) and the Sphere S3

NASA Astrophysics Data System (ADS)

Bernstein, Swanhild

2007-09-01

The construction of wavelets relies on translations and dilations which are perfectly given in R. On the sphere translations can be considered as rotations but it difficult to say what are dilations. For the 2-dimensional sphere there exist two different approaches to obtain wavelets which are worth to be considered. The first concept goes back to Freeden and collaborators [2] which defines wavelets by means of kernels of spherical singular integrals. The other concept developed by Antoine and Vandergheynst and coworkers [3] is a purely group theoretical approach and defines dilations as dilations in the tangent plane. Surprisingly both concepts coincides for zonal functions. We will define wavelets on the 3-dimensional sphere by means of kernels of singular integrals and demonstrate that wavelets constructed by Antoine and Vandergheynst for zonal functions meet our definition.

Contact mechanics for coated spheres that includes the transition from weak to strong adhesion

DOE PAGES

Reedy, Earl David

2007-09-01

Recently published results for a rigid spherical indenter contacting a thin, linear elastic coating on a rigid planar substrate have been extended to include the case of two contacting spheres, where each sphere is rigid and coated with a thin, linear elastic material. This is done by using an appropriately chosen effective radius and coating modulus. Finally, the earlier work has also been extended to provide analytical results that span the transition between the previously derived Derjaguin–Müller–Toporov (DMT)-like (work of adhesion/coating-modulus ratio is small) and Johnson–Kendall–Roberts (JKR)-like (work of adhesion/coating-modulus ratio is large) limits.

Synthesis and characterization of pHLIP® coated gold nanoparticles.

PubMed

Daniels, Jennifer L; Crawford, Troy M; Andreev, Oleg A; Reshetnyak, Yana K

2017-07-01

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP ® ) were introduced. The presence of a tumor-targeting pHLIP ® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP ® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Inter-slice Leakage Artifact Reduction Technique for Simultaneous Multi-Slice Acquisitions

PubMed Central

Cauley, Stephen F.; Polimeni, Jonathan R.; Bhat, Himanshu; Wang, Dingxin; Wald, Lawrence L.; Setsompop, Kawin

2015-01-01

Purpose Controlled aliasing techniques for simultaneously acquired EPI slices have been shown to significantly increase the temporal efficiency for both diffusion-weighted imaging (DWI) and fMRI studies. The “slice-GRAPPA” (SG) method has been widely used to reconstruct such data. We investigate robust optimization techniques for SG to ensure image reconstruction accuracy through a reduction of leakage artifacts. Methods Split slice-GRAPPA (SP-SG) is proposed as an alternative kernel optimization method. The performance of SP-SG is compared to standard SG using data collected on a spherical phantom and in-vivo on two subjects at 3T. Slice accelerated and non-accelerated data were collected for a spin-echo diffusion weighted acquisition. Signal leakage metrics and time-series SNR were used to quantify the performance of the kernel fitting approaches. Results The SP-SG optimization strategy significantly reduces leakage artifacts for both phantom and in-vivo acquisitions. In addition, a significant boost in time-series SNR for in-vivo diffusion weighted acquisitions with in-plane 2× and slice 3× accelerations was observed with the SP-SG approach. Conclusion By minimizing the influence of leakage artifacts during the training of slice-GRAPPA kernels, we have significantly improved reconstruction accuracy. Our robust kernel fitting strategy should enable better reconstruction accuracy and higher slice-acceleration across many applications. PMID:23963964

Deposition of GdVO4:Eu3+ nanoparticles on silica nanospheres by a simple sol gel method

NASA Astrophysics Data System (ADS)

Liu, Guixia; Hong, Guangyan; Wang, Jinxian; Dong, Xiangting

2006-07-01

The deposition and coating of GdVO4:Eu3+ nanoparticles on spherical silica was carried out using a simple sol-gel method at low temperature. The GdVO4:Eu3+-coated silica composites obtained were characterized by differential thermal analysis (DTA), thermogravimetric (TG) analysis, x-ray diffraction (XRD), Fourier-transform IR spectroscopy (FT-IR), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), photoluminescence spectra, and kinetic decay. It is found that the ~5 nm GdVO4:Eu3+ nanoparticles coating the silica spheres are crystal in the as-prepared samples and the crystallinity increases with increasing annealing temperature. The composites obtained are spherical in shape with an average size of 100 nm. The GdVO4:Eu3+ nanoparticles are linked with silica cores by a chemical bond. The photoluminescence spectra of the obtained GdVO4:Eu3+-coated silica composites are similar to those of the bulk GdVO4:Eu3+ phosphors. The strongest peak is near 617 nm, which indicates that Eu3+ is located in the low symmetry site with non-inversion centre.

Adhesive contact between a rigid spherical indenter and an elastic multi-layer coated substrate

PubMed Central

Stan, Gheorghe; Adams, George G.

2016-01-01

In this work the frictionless, adhesive contact between a rigid spherical indenter and an elastic multi-layer coated half-space was investigated by means of an integral transform formulation. The indented multi-layer coats were considered as made of isotropic layers that are perfectly bonded to each other and to an isotropic substrate. The adhesive interaction between indenter and contacting surface was treated as Maugis-type adhesion to provide general applicability within the entire range of adhesive interactions. By using a transfer matrix method, the stress-strain equations of the system were reduced to two coupled integral equations for the stress distribution under the indenter and the ratio between the adhesion radius and the contact radius, respectively. These resulting integral equations were solved through a numerical collocation technique, with solutions for the load dependencies of the contact radius and indentation depth for various values of the adhesion parameter and layer composition. The method developed here can be used to calculate the force-distance response of adhesive contacts on various inhomogeneous half-spaces that can be modeled as multi-layer coated half-spaces. PMID:27574338

Wet-chemical dissolution of TRISO-coated simulated high-temperature-reactor fuel particles

NASA Astrophysics Data System (ADS)

Skolo, K. P.; Jacobs, P.; Venter, J. H.; Klopper, W.; Crouse, P. L.

2012-01-01

Chemical etching with different mixtures of acidic solutions has been investigated to disintegrate the two outermost coatings from tri-structural isotropic coated particles containing zirconia kernels, which are used in simulated particles instead of uranium dioxide. A scanning electron microscope (SEM) was used to study the morphology of the particles after the first etching step as well as at different stages of the second etching step. SEM examination shows that the outer carbon layer can be readily removed with a CrO 3-HNO 3/H 2SO 4 solution. This finding was verified by energy dispersive spectroscopy (EDS) analysis. Etching of the silicon carbide layer in a hydrofluoric-nitric solution yielded partial removal of the coating and localized attack of the underlying coating layers. The SEM results provide evidence that the etching of the silicon carbide layer is strongly influenced by its microstructure.

Formulation and characterization of a compacted multiparticulate system for modified release of water-soluble drugs--Part II theophylline and cimetidine.

PubMed

Cantor, Stuart L; Hoag, Stephen W; Augsburger, Larry L

2009-05-01

The purpose was to investigate the effectiveness of an ethylcellulose (EC) bead matrix and different film-coating polymers in delaying drug release from compacted multiparticulate systems. Formulations containing theophylline or cimetidine granulated with Eudragit RS 30D were developed and beads were produced by extrusion-spheronization. Drug beads were coated using 15% wt/wt Surelease or Eudragit NE 30D and were evaluated for true density, particle size, and sphericity. Lipid-based placebo beads and drug beads were blended together and compacted on an instrumented Stokes B2 rotary tablet press. Although placebo beads were significantly less spherical, their true density of 1.21 g/cm(3) and size of 855 mum were quite close to Surelease-coated drug beads. Curing improved the crushing strength and friability values for theophylline tablets containing Surelease-coated beads; 5.7 +/- 1.0 kP and 0.26 +/- 0.07%, respectively. Dissolution profiles showed that the EC matrix only provided 3 h of drug release. Although tablets containing Surelease-coated theophylline beads released drug fastest overall (t(44.2%) = 8 h), profiles showed that coating damage was still minimal. Size and density differences indicated a minimal segregation potential during tableting for blends containing Surelease-coated drug beads. Although modified release profiles >8 h were achievable in tablets for both drugs using either coating polymer, Surelease-coated theophylline beads released drug fastest overall. This is likely because of the increased solubility of theophylline and the intrinsic properties of the Surelease films. Furthermore, the lipid-based placebos served as effective cushioning agents by protecting coating integrity of drug beads under a number of different conditions while tableting.

A Study of Stress Distribution in Layered and Gradient Tribological Coatings (Preprint)

DTIC Science & Technology

2006-11-01

FG) Ti/TiC coating design. On the top of the 440C stainless steel substrate, α-Ti is added as a bond layer with 50nm thickness to improve the... stainless steel substrate and the rigid spherical indenter was performed. Figure 5 (a) shows the normalized Hertzian point contact pressure distribution...AFRL-ML-WP-TP-2007-402 A STUDY OF STRESS DISTRIBUTION IN LAYERED AND GRADIENT TRIBOLOGICAL COATINGS (PREPRINT) Young Sup Kang, Shashi K

Post-Plasma SiOx Coatings of Metal and Metal Oxide Nanoparticles for Enhanced Thermal Stability and Tunable Photoactivity Applications

PubMed Central

Post, Patrick; Jidenko, Nicolas; Weber, Alfred P.; Borra, Jean-Pascal

2016-01-01

The plasma-based aerosol process developed for the direct coating of particles in gases with silicon oxide in a continuous chemical vapor deposition (CVD) process is presented. It is shown that non-thermal plasma filaments induced in a dielectric barrier discharge (DBD) at atmospheric pressure trigger post-DBD gas phase reactions. DBD operating conditions are first scanned to produce ozone and dinitrogen pentoxide. In the selected conditions, these plasma species react with gaseous tetraethyl orthosilicate (TEOS) precursor downstream of the DBD. The gaseous intermediates then condense on the surface of nanoparticles and self-reactions lead to homogeneous solid SiOx coatings, with thickness from nanometer to micrometer. This confirms the interest of post-DBD injection of the organo-silicon precursor to achieve stable production of actives species with subsequent controlled thickness of SiOx coatings. SiOx coatings of spherical and agglomerated metal and metal oxide nanoparticles (Pt, CuO, TiO2) are achieved. In the selected DBD operating conditions, the thickness of homogeneous nanometer sized coatings of spherical nanoparticles depends on the reaction duration and on the precursor concentration. For agglomerates, operating conditions can be tuned to cover preferentially the interparticle contact zones between primary particles, shifting the sintering of platinum agglomerates to much higher temperatures than the usual sintering temperature. Potential applications for enhanced thermal stability and tunable photoactivity of coated agglomerates are presented. PMID:28335219

Preparation of UC0.07-0.10N0.90-0.93 spheres for TRISO coated fuel particles

NASA Astrophysics Data System (ADS)

Hunt, R. D.; Silva, C. M.; Lindemer, T. B.; Johnson, J. A.; Collins, J. L.

2014-05-01

The US Department of Energy is considering a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with dense uranium nitride (UN) kernels with diameters of 650 or 800 μm. The objectives of this effort are to make uranium oxide microspheres with adequately dispersed carbon nanoparticles and to convert these microspheres into UN spheres, which could be then sintered into kernels. Recent improvements to the internal gelation process were successfully applied to the production of uranium gel spheres with different concentrations of carbon black. After the spheres were washed and dried, a simple two-step heat profile was used to produce porous microspheres with a chemical composition of UC0.07-0.10N0.90-0.93. The first step involved heating the microspheres to 2023 K in a vacuum, and in the second step, the microspheres were held at 1873 K for 6 h in flowing nitrogen.

Lesion contrast and detection using sonoelastographic shear velocity imaging: preliminary results

NASA Astrophysics Data System (ADS)

Hoyt, Kenneth; Parker, Kevin J.

2007-03-01

This paper assesses lesion contrast and detection using sonoelastographic shear velocity imaging. Shear wave interference patterns, termed crawling waves, for a two phase medium were simulated assuming plane wave conditions. Shear velocity estimates were computed using a spatial autocorrelation algorithm that operates in the direction of shear wave propagation for a given kernel size. Contrast was determined by analyzing shear velocity estimate transition between mediums. Experimental results were obtained using heterogeneous phantoms with spherical inclusions (5 or 10 mm in diameter) characterized by elevated shear velocities. Two vibration sources were applied to opposing phantom edges and scanned (orthogonal to shear wave propagation) with an ultrasound scanner equipped for sonoelastography. Demodulated data was saved and transferred to an external computer for processing shear velocity images. Simulation results demonstrate shear velocity transition between contrasting mediums is governed by both estimator kernel size and source vibration frequency. Experimental results from phantoms further indicates that decreasing estimator kernel size produces corresponding decrease in shear velocity estimate transition between background and inclusion material albeit with an increase in estimator noise. Overall, results demonstrate the ability to generate high contrast shear velocity images using sonoelastographic techniques and detect millimeter-sized lesions.

Body-wave traveltime and amplitude shifts from asymptotic travelling wave coupling

USGS Publications Warehouse

Pollitz, F.

2006-01-01

We explore the sensitivity of finite-frequency body-wave traveltimes and amplitudes to perturbations in 3-D seismic velocity structure relative to a spherically symmetric model. Using the approach of coupled travelling wave theory, we consider the effect of a structural perturbation on an isolated portion of the seismogram. By convolving the spectrum of the differential seismogram with the spectrum of a narrow window taper, and using a Taylor's series expansion for wavenumber as a function of frequency on a mode dispersion branch, we derive semi-analytic expressions for the sensitivity kernels. Far-field effects of wave interactions with the free surface or internal discontinuities are implicitly included, as are wave conversions upon scattering. The kernels may be computed rapidly for the purpose of structural inversions. We give examples of traveltime sensitivity kernels for regional wave propagation at 1 Hz. For the direct SV wave in a simple crustal velocity model, they are generally complicated because of interfering waves generated by interactions with the free surface and the Mohorovic??ic?? discontinuity. A large part of the interference effects may be eliminated by restricting the travelling wave basis set to those waves within a certain range of horizontal phase velocity. ?? Journal compilation ?? 2006 RAS.

Method of making quasicrystal alloy powder, protective coatings and articles

DOEpatents

Shield, Jeffrey E.; Goldman, Alan I.; Anderson, Iver E.; Ellis, Timothy W.; McCallum, R. William; Sordelet, Daniel J.

1995-07-18

A method of making quasicrystalline alloy particulates wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture.

2009 Insensitive Munitions and Energetic Materials Technology Symposium

DTIC Science & Technology

2009-05-14

Multilayer Structure 1D STIMULI Flat end rod Round end rod Flat cookie -cutter Spherical fragment Simple shaped charge jet Real shaped charge jet Thin plate... cookie -cutter Spherical fragment Simple shaped charge jet Real shaped charge jet Thin plate Constant Temperature Rising Temperature Multilayer...Propellants  Plasticizer mixed into the Propellant - Dough NO SURFACE COATING Formulation Impetus (J/g) Flame Temp (K) Mw (g/mole) A

Exploring microwave resonant multi-point ignition using high-speed schlieren imaging

NASA Astrophysics Data System (ADS)

Liu, Cheng; Zhang, Guixin; Xie, Hong; Deng, Lei; Wang, Zhi

2018-03-01

Microwave plasma offers a potential method to achieve rapid combustion in a high-speed combustor. In this paper, microwave resonant multi-point ignition and its control method have been studied via high-speed schlieren imaging. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. The microwave pulse in 2.45 GHz with 2 ms width and 3 kW peak power was employed as an ignition energy source to produce initial flame kernels in the combustion chamber. A reflective schlieren method was designed to illustrate the flame development process with a high-speed camera. The bottom of the combustion chamber was made of a quartz glass coated with indium tin oxide, which ensures sufficient microwave reflection and light penetration. Ignition experiments were conducted at 2 bars of stoichiometric methane-air mixtures. Schlieren images show that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in different flame kernels. Ignition kernels were discussed in three types according to their appearances. Pressure curves and combustion duration also show that multi-point ignition plays a significant role in accelerating combustion.

Exploring microwave resonant multi-point ignition using high-speed schlieren imaging.

PubMed

Liu, Cheng; Zhang, Guixin; Xie, Hong; Deng, Lei; Wang, Zhi

2018-03-01

Microwave plasma offers a potential method to achieve rapid combustion in a high-speed combustor. In this paper, microwave resonant multi-point ignition and its control method have been studied via high-speed schlieren imaging. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. The microwave pulse in 2.45 GHz with 2 ms width and 3 kW peak power was employed as an ignition energy source to produce initial flame kernels in the combustion chamber. A reflective schlieren method was designed to illustrate the flame development process with a high-speed camera. The bottom of the combustion chamber was made of a quartz glass coated with indium tin oxide, which ensures sufficient microwave reflection and light penetration. Ignition experiments were conducted at 2 bars of stoichiometric methane-air mixtures. Schlieren images show that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in different flame kernels. Ignition kernels were discussed in three types according to their appearances. Pressure curves and combustion duration also show that multi-point ignition plays a significant role in accelerating combustion.

Height system unification based on the Fixed Geodetic Boundary Value Problem with limited availability of gravity data

NASA Astrophysics Data System (ADS)

Porz, Lucas; Grombein, Thomas; Seitz, Kurt; Heck, Bernhard; Wenzel, Friedemann

2017-04-01

Regional height reference systems are generally related to individual vertical datums defined by specific tide gauges. The discrepancies of these vertical datums with respect to a unified global datum cause height system biases that range in an order of 1-2 m at a global scale. One approach for unification of height systems relates to the solution of a Geodetic Boundary Value Problem (GBVP). In particular, the fixed GBVP, using gravity disturbances as boundary values, is solved at GNSS/leveling benchmarks, whereupon height datum offsets can be estimated by least squares adjustment. In spherical approximation, the solution of the fixed GBVP is obtained by Hotine's spherical integral formula. However, this method relies on the global availability of gravity data. In practice, gravity data of the necessary resolution and accuracy is not accessible globally. Thus, the integration is restricted to an area within the vicinity of the computation points. The resulting truncation error can reach several meters in height, making height system unification without further consideration of this effect unfeasible. This study analyzes methods for reducing the truncation error by combining terrestrial gravity data with satellite-based global geopotential models and by modifying the integral kernel in order to accelerate the convergence of the resulting potential. For this purpose, EGM2008-derived gravity functionals are used as pseudo-observations to be integrated numerically. Geopotential models of different spectral degrees are implemented using a remove-restore-scheme. Three types of modification are applied to the Hotine-kernel and the convergence of the resulting potential is analyzed. In a further step, the impact of these operations on the estimation of height datum offsets is investigated within a closed loop simulation. A minimum integration radius in combination with a specific modification of the Hotine-kernel is suggested in order to achieve sub-cm accuracy for the estimation of height datum offsets.

A balance between membrane elasticity and polymerization energy sets the shape of spherical clathrin coats

NASA Astrophysics Data System (ADS)

Saleem, Mohammed; Morlot, Sandrine; Hohendahl, Annika; Manzi, John; Lenz, Martin; Roux, Aurélien

2015-02-01

In endocytosis, scaffolding is one of the mechanisms to create membrane curvature by moulding the membrane into the spherical shape of the clathrin cage. However, the impact of membrane elastic parameters on the assembly and shape of clathrin lattices has never been experimentally evaluated. Here, we show that membrane tension opposes clathrin polymerization. We reconstitute clathrin budding in vitro with giant unilamellar vesicles (GUVs), purified adaptors and clathrin. By changing the osmotic conditions, we find that clathrin coats cause extensive budding of GUVs under low membrane tension while polymerizing into shallow pits under moderate tension. High tension fully inhibits polymerization. Theoretically, we predict the tension values for which transitions between different clathrin coat shapes occur. We measure the changes in membrane tension during clathrin polymerization, and use our theoretical framework to estimate the polymerization energy from these data. Our results show that membrane tension controls clathrin-mediated budding by varying the membrane budding energy.

Preparation of ultra-fine powders from polysaccharide-coated solid lipid nanoparticles and nanostructured lipid carriers by innovative nano spray drying technology.

PubMed

Wang, Taoran; Hu, Qiaobin; Zhou, Mingyong; Xue, Jingyi; Luo, Yangchao

2016-09-10

In this study, five polysaccharides were applied as natural polymeric coating materials to prepare solid lipid nanoparticles (SLN) and nanostructure lipid carriers (NLC), and then the obtained lipid colloidal particles were transformed to solid powders by the innovative nano spray drying technology. The feasibility and suitability of this new technology to generate ultra-fine lipid powder particles were evaluated and the formulation was optimized. The spray dried SLN powder exhibited the aggregated and irregular shape and dimension, but small, uniform, well-separated spherical powder particles of was obtained from NLC. The optimal formulation of NLC was prepared by a 20-30% oleic acid content with carrageenan or pectin as coating material. Therefore, nano spray drying technology has a potential application to produce uniform, spherical, and sub-microscale lipid powder particles when the formulation of lipid delivery system is appropriately designed. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrical four-point probing of spherical metallic thin films coated onto micron sized polymer particles

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

Pettersen, Sigurd R., E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no; Stokkeland, August Emil; Zhang, Zhiliang

Micron-sized metal-coated polymer spheres are frequently used as filler particles in conductive composites for electronic interconnects. However, the intrinsic electrical resistivity of the spherical thin films has not been attainable due to deficiency in methods that eliminate the effect of contact resistance. In this work, a four-point probing method using vacuum compatible piezo-actuated micro robots was developed to directly investigate the electric properties of individual silver-coated spheres under real-time observation in a scanning electron microscope. Poly(methyl methacrylate) spheres with a diameter of 30 μm and four different film thicknesses (270 nm, 150 nm, 100 nm, and 60 nm) were investigated. By multiplying the experimental resultsmore » with geometrical correction factors obtained using finite element models, the resistivities of the thin films were estimated for the four thicknesses. These were higher than the resistivity of bulk silver.« less

Synthesis of carbon-coated Na2MnPO4F hollow spheres as a potential cathode material for Na-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Ling; Hu, Yong; Zhang, Xiaoping; Liu, Jiequn; Zhu, Xing; Zhong, Shengkui

2018-01-01

Hollow sphere structure Na2MnPO4F/C composite is synthesized through spray drying, following in-situ pyrolytic carbon coating process. XRD results indicate that the well crystallized composite can be successfully synthesized, and no other impurity phases are detected. SEM and TEM results reveal that the Na2MnPO4F/C samples show intact hollow spherical architecture, and the hollow spherical shells with an average thickness of 150 nm-250 nm are composed of nanosized primary particles. Furthermore, the amorphous carbon layer is uniformly coated on the surface of the hollow sphere, and the nanosized Na2MnPO4F particles are well embedded in the carbon networks. Consequently, the hollow sphere structure Na2MnPO4F/C shows enhanced electrochemical performance. Especially, it is the first time that the obvious potential platforms (∼3.6 V) are observed during the charge and discharge process at room temperature.

A particle swarm optimized kernel-based clustering method for crop mapping from multi-temporal polarimetric L-band SAR observations

NASA Astrophysics Data System (ADS)

Tamiminia, Haifa; Homayouni, Saeid; McNairn, Heather; Safari, Abdoreza

2017-06-01

Polarimetric Synthetic Aperture Radar (PolSAR) data, thanks to their specific characteristics such as high resolution, weather and daylight independence, have become a valuable source of information for environment monitoring and management. The discrimination capability of observations acquired by these sensors can be used for land cover classification and mapping. The aim of this paper is to propose an optimized kernel-based C-means clustering algorithm for agriculture crop mapping from multi-temporal PolSAR data. Firstly, several polarimetric features are extracted from preprocessed data. These features are linear polarization intensities, and several statistical and physical based decompositions such as Cloude-Pottier, Freeman-Durden and Yamaguchi techniques. Then, the kernelized version of hard and fuzzy C-means clustering algorithms are applied to these polarimetric features in order to identify crop types. The kernel function, unlike the conventional partitioning clustering algorithms, simplifies the non-spherical and non-linearly patterns of data structure, to be clustered easily. In addition, in order to enhance the results, Particle Swarm Optimization (PSO) algorithm is used to tune the kernel parameters, cluster centers and to optimize features selection. The efficiency of this method was evaluated by using multi-temporal UAVSAR L-band images acquired over an agricultural area near Winnipeg, Manitoba, Canada, during June and July in 2012. The results demonstrate more accurate crop maps using the proposed method when compared to the classical approaches, (e.g. 12% improvement in general). In addition, when the optimization technique is used, greater improvement is observed in crop classification, e.g. 5% in overall. Furthermore, a strong relationship between Freeman-Durden volume scattering component, which is related to canopy structure, and phenological growth stages is observed.

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

McMurray, Jacob W.; Lindemer, Terrence B.; Brown, Nicholas R.

There are three important failure mechanisms that must be controlled in high-temperature gas-cooled reactor (HTGR) fuel for certain higher burnup applications are SiC layer rupture, SiC corrosion by CO, and coating compromise from kernel migration. All are related to high CO pressures stemming from free O generated when uranium present as UO 2 fissions and the O is not subsequently bound by other elements. Furthermore, in the HTGR UCO kernel design, CO buildup from excess O is controlled by the inclusion of additional uranium in the form of a carbide, UC x. An approach for determining the minimum UC xmore » content to ensure negligible CO formation was developed and demonstrated using CALPHAD models and the Serpent 2 reactor physics and depletion analysis tool. Our results are intended to be more accurate than previous estimates by including more nuclear and chemical factors, in particular the effect of transmutation products on the oxygen distribution as the fuel kernel composition evolves with burnup.« less

Advances in the Development of a WCl6 CVD System for Coating UO2 Powders with Tungsten

NASA Technical Reports Server (NTRS)

Mireles, Omar R.; Tieman, Alyssa; Broadway, Jeramie; Hickman, Robert

2013-01-01

Demonstrated viability and utilization of: a) Fluidized powder bed. b) WCl6 CVD process. c) Coated spherical particles with tungsten. The highly corrosive nature of the WCl6 solid reagent limits material of construction. Indications that identifying optimized process variables with require substantial effort and will likely vary with changes in fuel requirements.

Method of making quasicrystal alloy powder, protective coatings and articles

DOEpatents

Shield, J.E.; Goldman, A.I.; Anderson, I.E.; Ellis, T.W.; McCallum, R.W.; Sordelet, D.J.

1995-07-18

A method of making quasicrystalline alloy particulates is disclosed wherein an alloy is superheated and the melt is atomized to form generally spherical alloy particulates free of mechanical fracture and exhibiting a predominantly quasicrystalline in the atomized condition structure. The particulates can be plasma sprayed to form a coating or consolidated to form an article of manufacture. 3 figs.

Controlled assembly of nanoparticle structures: spherical and toroidal superlattices and nanoparticle-coated polymeric beads.

PubMed

Isojima, Tatsushi; Suh, Su Kyung; Vander Sande, John B; Hatton, T Alan

2009-07-21

The emulsion droplet solvent evaporation method has been used to prepare nanoclusters of monodisperse magnetite nanoparticles of varying morphologies depending on the temperature and rate of solvent evaporation and on the composition (solvent, presence of polymer, nanoparticle concentration, etc.) of the emulsion droplets. In the absence of a polymer, and with increasing solvent evaporation temperatures, the nanoparticles formed single- or multidomain crystalline superlattices, amorphous spherical aggregates, or toroidal clusters, as determined by the energetics and dynamics of the solvent evaporation process. When polymers that are incompatible with the nanoparticle coatings were included in the emulsion formulation, monolayer- and multilayer-coated polymer beads and partially coated Janus beads were prepared; the nanoparticles were expelled by the polymer as its concentration increased on evaporation of the solvent and accumulated on the surfaces of the beads in a well-ordered structure. The precise number of nanoparticle layers depended on the polymer/magnetic nanoparticle ratio in the oil droplet phase parent emulsion. The magnetic nanoparticle superstructures responded to the application of a modest magnetic field by forming regular chains with alignment of nonuniform structures (e.g., toroids and Janus beads) that are in accord with theoretical predictions and with observations in other systems.

Generalized and efficient algorithm for computing multipole energies and gradients based on Cartesian tensors

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

Lin, Dejun, E-mail: dejun.lin@gmail.com

2015-09-21

Accurate representation of intermolecular forces has been the central task of classical atomic simulations, known as molecular mechanics. Recent advancements in molecular mechanics models have put forward the explicit representation of permanent and/or induced electric multipole (EMP) moments. The formulas developed so far to calculate EMP interactions tend to have complicated expressions, especially in Cartesian coordinates, which can only be applied to a specific kernel potential function. For example, one needs to develop a new formula each time a new kernel function is encountered. The complication of these formalisms arises from an intriguing and yet obscured mathematical relation between themore » kernel functions and the gradient operators. Here, I uncover this relation via rigorous derivation and find that the formula to calculate EMP interactions is basically invariant to the potential kernel functions as long as they are of the form f(r), i.e., any Green’s function that depends on inter-particle distance. I provide an algorithm for efficient evaluation of EMP interaction energies, forces, and torques for any kernel f(r) up to any arbitrary rank of EMP moments in Cartesian coordinates. The working equations of this algorithm are essentially the same for any kernel f(r). Recently, a few recursive algorithms were proposed to calculate EMP interactions. Depending on the kernel functions, the algorithm here is about 4–16 times faster than these algorithms in terms of the required number of floating point operations and is much more memory efficient. I show that it is even faster than a theoretically ideal recursion scheme, i.e., one that requires 1 floating point multiplication and 1 addition per recursion step. This algorithm has a compact vector-based expression that is optimal for computer programming. The Cartesian nature of this algorithm makes it fit easily into modern molecular simulation packages as compared with spherical coordinate-based algorithms. A software library based on this algorithm has been implemented in C++11 and has been released.« less

Interactions of non-spherical particles in simple flows

NASA Astrophysics Data System (ADS)

Niazi, Mehdi; Brandt, Luca; Costa, Pedro; Breugem, Wim-Paul

2015-11-01

The behavior of particles in a flow affects the global transport and rheological properties of the mixture. In recent years much effort has been therefore devoted to the development of an efficient method for the direct numerical simulation (DNS) of the motion of spherical rigid particles immersed in an incompressible fluid. However, the literature on non-spherical particle suspensions is quite scarce despite the fact that these are more frequent. We develop a numerical algorithm to simulate finite-size spheroid particles in shear flows to gain new understanding of the flow of particle suspensions. In particular, we wish to understand the role of inertia and its effect on the flow behavior. For this purpose, DNS simulations with a direct-forcing immersed boundary method are used, with collision and lubrication models for particle-particle and particle-wall interactions. We will discuss pair interactions, relative motion and rotation, of two sedimenting spheroids and show that the interaction time increases significantly for non-spherical particles. More interestingly, we show that the particles are attracted to each other from larger lateral displacements. This has important implications for collision kernels. This work was supported by the European Research Council Grant No. ERC-2013-CoG-616186, TRITOS, and by the Swedish Research Council (VR).

Effect of Local TOF Kernel Miscalibrations on Contrast-Noise in TOF PET

NASA Astrophysics Data System (ADS)

Clementel, Enrico; Mollet, Pieter; Vandenberghe, Stefaan

2013-06-01

TOF PET imaging requires specific calibrations: accurate characterization of the system timing resolution and timing offset is required to achieve the full potential image quality. Current system models used in image reconstruction assume a spatially uniform timing resolution kernel. Furthermore, although the timing offset errors are often pre-corrected, this correction becomes less accurate with the time since, especially in older scanners, the timing offsets are often calibrated only during the installation, as the procedure is time-consuming. In this study, we investigate and compare the effects of local mismatch of timing resolution when a uniform kernel is applied to systems with local variations in timing resolution and the effects of uncorrected time offset errors on image quality. A ring-like phantom was acquired on a Philips Gemini TF scanner and timing histograms were obtained from coincidence events to measure timing resolution along all sets of LORs crossing the scanner center. In addition, multiple acquisitions of a cylindrical phantom, 20 cm in diameter with spherical inserts, and a point source were simulated. A location-dependent timing resolution was simulated, with a median value of 500 ps and increasingly large local variations, and timing offset errors ranging from 0 to 350 ps were also simulated. Images were reconstructed with TOF MLEM with a uniform kernel corresponding to the effective timing resolution of the data, as well as with purposefully mismatched kernels. To CRC vs noise curves were measured over the simulated cylinder realizations, while the simulated point source was processed to generate timing histograms of the data. Results show that timing resolution is not uniform over the FOV of the considered scanner. The simulated phantom data indicate that CRC is moderately reduced in data sets with locally varying timing resolution reconstructed with a uniform kernel, while still performing better than non-TOF reconstruction. On the other hand, uncorrected offset errors in our setup have a larger potential for decreasing image quality and can lead to a reduction of CRC of up to 15% and an increase in the measured timing resolution kernel up to 40%. However, in realistic conditions in frequently calibrated systems, using a larger effective timing kernel in image reconstruction can compensate uncorrected offset errors.

Microwave vector radiative transfer equation of a sea foam layer by the second-order Rayleigh approximation

NASA Astrophysics Data System (ADS)

Wei, En-Bo

2011-10-01

The microwave vector radiative transfer (VRT) equation of a coated spherical bubble layer is derived by means of the second-order Rayleigh approximation field when the microwave wavelength is larger than the coated spherical particle diameter. Meanwhile, the perturbation method is developed to solve the second-order Rayleigh VRT equation for the small ratio of the volume scattering coefficient to the extinction coefficient. As an example, the emissive properties of a sea surface foam layer, which consists of seawater coated bubbles, are investigated. The extinction, absorption, and scattering coefficients of sea foam are obtained by the second-order Rayleigh approximation fields and discussed for the different microwave frequencies and the ratio of inner radius to outer radius of a coated bubble. Our results show that in the dilute limit, the volume scattering coefficient decreases with increasing the ratio of inner radius to outer radius and decreasing the frequencies. It is also found that the microwave emissivity and the extinction coefficient have a peak at very thin seawater coating and its peak value decreases with frequency decrease. Furthermore, with the VRT equation and effective medium approximation of densely coated bubbles, the mechanism of sea foam enhancing the emissivity of a sea surface is disclosed. In addition, excellent agreement is obtained by comparing our VRT results with the experimental data of microwave emissivities of sea surface covered by a sea foam layer at L-band (1.4 GHz) and the Camps' model.

The effect of ZnO nanoparticle coating on the frictional resistance between orthodontic wires and ceramic brackets

PubMed Central

Behroozian, Ahmad; Kachoei, Mojgan; Khatamian, Masumeh; Divband, Baharak

2016-01-01

Background. Any decrease in friction between orthodontic wire and bracket can accelerate tooth movement in the sliding technique and result in better control of anchorage. This study was carried out to evaluate frictional forces by coating orthodontic wires and porcelain brackets with zinc oxide nanoparticles (ZnO). Methods. In this in vitro study, we evaluated a combination of 120 samples of 0.019×0.025 stainless steel (SS) orthodonticwires and 22 mil system edgewise porcelain brackets with and without spherical zinc oxide nanoparticles. Spherical ZnOnanoparticles were deposited on wires and brackets by immersing them in ethanol solution and SEM (scanning electronmicroscope) evaluation confirmed the presence of the ZnO coating. The frictional forces were calculated between the wiresand brackets in four groups: group ZZ (coated wire and bracket), group OO (uncoated wire and bracket), group ZO (coatedwire and uncoated bracket) and group OZ (uncoated wire and coated bracket). Kolmogorov-Smirnov, Mann-Whitney andKruskal-Wallis tests were used for data analysis. Results. The frictional force in ZZ (3.07±0.4 N) was the highest (P <0.05), and OZ (2.18±0.5 N) had the lowest amount of friction (P <0.05) among the groups. There was no significant difference in frictional forces between the ZO and OO groups (2.65±0.2 and 2.70±0.2 N, respectively). Conclusion. Coating of porcelain bracket surfaces with ZnO nanoparticles can decrease friction in the sliding technique,and wire coating combined with bracket coating is not recommended due to its effect on friction. PMID:27429727

Arabinoxylan-lipids-based edible films and coatings. 2. Influence of sucroester nature on the emulsion structure and film properties.

PubMed

Phan The, D; Péroval, C; Debeaufort, F; Despré, D; Courthaudon, J L; Voilley, A

2002-01-16

This work is a contribution to better knowledge of the influence of the structure of films on their functional properties obtained from emulsions based on arabinoxylans, hydrogenated palm kernel oil (HPKO), and emulsifiers. The sucroesters (emulsifiers) have a great effect on the stabilization of the emulsified film structure containing arabinoxylans and hydrogenated palm kernel oil. They improve the moisture barrier properties. Several sucroesters having different esterification degrees were tested. Both lipophilic (90% of di and tri-ester) and hydrophilic (70% of mono-ester) sucrose esters can ensure the stability of the emulsion used to form the film, especially during preparation and drying. These emulsifiers confer good moisture barrier properties to emulsified films.

Design Evolutuion of Hot Isotatic Press Cans for NTP Cermet Fuel Fabrication

NASA Technical Reports Server (NTRS)

Mireles, O. R.; Broadway, J.; Hickman, R.

2014-01-01

Nuclear Thermal Propulsion (NTP) is under consideration for potential use in deep space exploration missions due to desirable performance properties such as a high specific impulse (> 850 seconds). Tungsten (W)-60vol%UO2 cermet fuel elements are under development, with efforts emphasizing fabrication, performance testing and process optimization to meet NTP service life requirements [1]. Fuel elements incorporate design features that provide redundant protection from crack initiation, crack propagation potentially resulting in hot hydrogen (H2) reduction of UO2 kernels. Fuel erosion and fission product retention barriers include W coated UO2 fuel kernels, W clad internal flow channels and fuel element external W clad resulting in a fully encapsulated fuel element design as shown.

Fluorescence labeling of colloidal core-shell particles with defined isoelectric points for in vitro studies.

PubMed

Daberkow, Timo; Meder, Fabian; Treccani, Laura; Schowalter, Marco; Rosenauer, Andreas; Rezwan, Kurosch

2012-02-01

In the light of in vitro nanotoxicological studies fluorescence labeling has become standard for particle localization within the cell environment. However, fluorescent labeling is also known to significantly alter the particle surface chemistry and therefore potentially affect the outcome of cell studies. Hence, fluorescent labeling is ideally carried out without changing, for example, the isoelectric point. A simple and straightforward method for obtaining fluorescently labeled spherical metal oxide particles with well-defined isoelectric points and a narrow size distribution is presented in this study. Spherical amorphous silica (SiO2, 161 nm diameter) particles were used as the substrate material and were coated with silica, alumina (Al2O3), titania (TiO2), or zirconia (ZrO2) using sol-gel chemistry. Fluorescent labeling was achieved by directly embedding rhodamine 6G dye in the coating matrix without affecting the isoelectric point of the metal oxide coatings. The coating quality was confirmed by high resolution transmission electron microscopy, energy filtered transmission electron microscopy and electrochemical characterization. The coatings were proven to be stable for at least 240 h under different pH conditions. The well-defined fluorescent particles can be directly used for biomedical investigations, e.g. elucidation of particle-cell interactions in vitro. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Shape Effect in the Design of Nanowire Coated Microparticles as Transepithelial Drug Delivery Devices

PubMed Central

Uskoković, Vuk; Lee, Kunwoo; Lee, Phin Peng; Fischer, Kathleen E.; Desai, Tejal A.

2012-01-01

While the oral drug delivery route has traditionally been the most popular among patients, it is estimated that 90 % of therapeutic compounds possess oral bioavailability limitations. Thus, the development of novel drug carriers for more effective oral delivery of therapeutics is an important goal. Composite particles made by growing nanoscopic silicon wires from the surface of narrowly dispersed, microsized silica beads were previously shown to be able to: (a) adhere well onto the epithelium by interdigitating their nanowires with the apical microvilli; and (b) increase the permeability of Caco-2 cell monolayers with respect to small organic molecules in direct proportion to their concentration. A comparison between the effects of spherical and planar particle morphologies on the permeability of the epithelial cell layer in vitro and in vivo presented the subject of this study. Owing to their larger surface area, the planar particles exhibited a higher drug loading efficiency than their spherical counterparts, while simultaneously increasing the transepithelial permeation of a moderately sized model drug, insulin. The insulin elution profile for planar nanowire-coated particles displayed a continual increase in the cumulative amount of the released drug, approaching a constant release rate for 1 – 4 h period of the elution time. An immunohistochemical study confirmed the ability of planar silica particles coated with nanowires to loosen the tight junction of the epithelial cells to a greater extent than the spherical particles did, thus enabling a more facile transport of the drug across the epithelium. Transepithelial permeability tests conducted for model drugs ranging in size from 0.4 to 150 kDa yielded three categories of molecules depending on their permeation propensities. Insulin belonged to the category of molecules deliverable across the epithelium only with the assistance of nanowire-coated particles. Other groups of drugs, smaller and bigger, respectively, either did not need the carrier to permeate the epithelium or were not able to cross it even with the support from the nanowire-coated particles. Bioavailability of insulin orally administered to rabbits was also found to be increased when delivered in conjunction with the nanowire-coated planar particles. PMID:22900471

Evaluation of design parameters for TRISO-coated fuel particles to establish manufacturing critical limits using PARFUME

DOE PAGES

Skerjanc, William F.; Maki, John T.; Collin, Blaise P.; ...

2015-12-02

The success of modular high temperature gas-cooled reactors is highly dependent on the performance of the tristructural-isotopic (TRISO) coated fuel particle and the quality to which it can be manufactured. During irradiation, TRISO-coated fuel particles act as a pressure vessel to contain fission gas and mitigate the diffusion of fission products to the coolant boundary. The fuel specifications place limits on key attributes to minimize fuel particle failure under irradiation and postulated accident conditions. PARFUME (an integrated mechanistic coated particle fuel performance code developed at the Idaho National Laboratory) was used to calculate fuel particle failure probabilities. By systematically varyingmore » key TRISO-coated particle attributes, failure probability functions were developed to understand how each attribute contributes to fuel particle failure. Critical manufacturing limits were calculated for the key attributes of a low enriched TRISO-coated nuclear fuel particle with a kernel diameter of 425 μm. As a result, these critical manufacturing limits identify ranges beyond where an increase in fuel particle failure probability is expected to occur.« less

Influence of the Host Contact Sequence on the Outcome of Competition among Aspergillus flavus Isolates during Host Tissue Invasion▿

PubMed Central

Mehl, H. L.; Cotty, P. J.

2011-01-01

Biological control of aflatoxin contamination by Aspergillus flavus is achieved through competitive exclusion of aflatoxin producers by atoxigenic strains. Factors dictating the extent to which competitive displacement occurs during host infection are unknown. The role of initial host contact in competition between pairs of A. flavus isolates coinfecting maize kernels was examined. Isolate success during tissue invasion and reproduction was assessed by quantification of isolate-specific single nucleotide polymorphisms using pyrosequencing. Isolates were inoculated either simultaneously or 1 h apart. Increased success during competition was conferred to the first isolate to contact the host independent of that isolate's innate competitive ability. The first-isolate advantage decreased with the conidial concentration, suggesting capture of limited resources on kernel surfaces contributes to competitive exclusion. Attempts to modify access to putative attachment sites by either coating kernels with dead conidia or washing kernels with solvents did not influence the success of the first isolate, suggesting competition for limited attachment sites on kernel surfaces does not mediate first-isolate advantage. The current study is the first to demonstrate an immediate competitive advantage conferred to A. flavus isolates upon host contact and prior to either germ tube emergence or host colonization. This suggests the timing of host contact is as important to competition during disease cycles as innate competitive ability. Early dispersal to susceptible crop components may allow maintenance within A. flavus populations of genetic types with low competitive ability during host tissue invasion. PMID:21216896

Protozoal Digestion of Coat-Defective Bacillus subtilis Spores Produces “Rinds” Composed of Insoluble Coat Protein▿

PubMed Central

Carroll, Alicia Monroe; Plomp, Marco; Malkin, Alexander J.; Setlow, Peter

2008-01-01

The Bacillus subtilis spore coat is a multilayer, proteinaceous structure that consists of more than 50 proteins. Located on the surface of the spore, the coat provides resistance to potentially toxic molecules as well as to predation by the protozoan Tetrahymena thermophila. When coat-defective spores are fed to Tetrahymena, the spores are readily digested. However, a residue termed a “rind” that looks like coat material remains. As observed with a phase-contrast microscope, the rinds are spherical or hemispherical structures that appear to be devoid of internal contents. Atomic force microscopy and chemical analyses showed that (i) the rinds are composed of insoluble protein largely derived from both outer and inner spore coat layers, (ii) the amorphous layer of the outer coat is largely responsible for providing spore resistance to protozoal digestion, and (iii) the rinds and intact spores do not contain significant levels of silicon. PMID:18689521

Biocompatibly Coated 304 Stainless Steel as Superior Corrosion-Resistant Implant Material to 316L Steel

NASA Astrophysics Data System (ADS)

Paul, Subir; Mandal, Chandranath

2013-10-01

Surface treatments of 304 stainless steel by electro-coating and passivating in few inorganic electrolytes were found to be very effective in drastically reducing the corrosion rate of the material in stimulated body fluid (SBF) by several orders in comparison to that of 316L steel, presently being used for orthopedic implants. Polarization studies of electrodeposited hydroxyl apatite coating on 304 steel showed remarkably improved corrosion current. Cyclic polarization of the material in SBF reflected the broadened passivity region, much lower passive current, and narrower hysteresis loops. Similar effects were also found through the formation of inorganic coatings by passivation in NaF, CaNO3, and calcium phosphate buffer solutions. Surface characterization by XRD showed the peaks of the respective coating crystals. The morphology of the coatings studied by SEM showed a flake-type structure for hydroxyapatite coating and fine spherical-subspherical particles for other coatings.

Design and calculation of low infrared transmittance and low emissivity coatings for heat radiative applications

NASA Astrophysics Data System (ADS)

Wang, Guang-Hai; Zhang, Yue; Zhang, Da-Hai; Fan, Jin-Peng

2012-02-01

The infrared transmittance and emissivity of heat-insulating coatings pigmented with various structural particles were studied using Kubelka-Munk theory and Mie theory. The primary design purpose was to obtain the low transmittance and low emissivity coatings to reduce the heat transfer by thermal radiation for high-temperature applications. In the case of silica coating layers constituted with various structural titania particles (solid, hollow, and core-shell spherical), the dependence of transmittance and emissivity of the coating layer on the particle structure and the layer thickness was investigated and optimized. The results indicate that the coating pigmented with core-shell titania particles exhibits a lower infrared transmittance and a lower emissivity value than that with other structural particles and is suitable to radiative heat-insulating applications.

Linkage disequilibrium, SNP frequency change due to selection, and association mapping in popcorn chromosome regions containing QTLs for quality traits

PubMed Central

Paes, Geísa Pinheiro; Viana, José Marcelo Soriano; Silva, Fabyano Fonseca e; Mundim, Gabriel Borges

2016-01-01

Abstract The objectives of this study were to assess linkage disequilibrium (LD) and selection-induced changes in single nucleotide polymorphism (SNP) frequency, and to perform association mapping in popcorn chromosome regions containing quantitative trait loci (QTLs) for quality traits. Seven tropical and two temperate popcorn populations were genotyped for 96 SNPs chosen in chromosome regions containing QTLs for quality traits. The populations were phenotyped for expansion volume, 100-kernel weight, kernel sphericity, and kernel density. The LD statistics were the difference between the observed and expected haplotype frequencies (D), the proportion of D relative to the expected maximum value in the population, and the square of the correlation between the values of alleles at two loci. Association mapping was based on least squares and Bayesian approaches. In the tropical populations, D-values greater than 0.10 were observed for SNPs separated by 100-150 Mb, while most of the D-values in the temperate populations were less than 0.05. Selection for expansion volume indirectly led to increase in LD values, population differentiation, and significant changes in SNP frequency. Some associations were observed for expansion volume and the other quality traits. The candidate genes are involved with starch, storage protein, lipid, and cell wall polysaccharides synthesis. PMID:27007903

Linkage disequilibrium, SNP frequency change due to selection, and association mapping in popcorn chromosome regions containing QTLs for quality traits.

PubMed

Paes, Geísa Pinheiro; Viana, José Marcelo Soriano; Silva, Fabyano Fonseca E; Mundim, Gabriel Borges

2016-03-01

The objectives of this study were to assess linkage disequilibrium (LD) and selection-induced changes in single nucleotide polymorphism (SNP) frequency, and to perform association mapping in popcorn chromosome regions containing quantitative trait loci (QTLs) for quality traits. Seven tropical and two temperate popcorn populations were genotyped for 96 SNPs chosen in chromosome regions containing QTLs for quality traits. The populations were phenotyped for expansion volume, 100-kernel weight, kernel sphericity, and kernel density. The LD statistics were the difference between the observed and expected haplotype frequencies (D), the proportion of D relative to the expected maximum value in the population, and the square of the correlation between the values of alleles at two loci. Association mapping was based on least squares and Bayesian approaches. In the tropical populations, D-values greater than 0.10 were observed for SNPs separated by 100-150 Mb, while most of the D-values in the temperate populations were less than 0.05. Selection for expansion volume indirectly led to increase in LD values, population differentiation, and significant changes in SNP frequency. Some associations were observed for expansion volume and the other quality traits. The candidate genes are involved with starch, storage protein, lipid, and cell wall polysaccharides synthesis.

Effect of surfactant concentration and solidification temperature on the characteristics and stability of nanostructured lipid carrier (NLC) prepared from rambutan (Nephelium lappaceum L.) kernel fat.

PubMed

Witayaudom, Pimchanok; Klinkesorn, Utai

2017-11-01

Nanostructured lipid carrier (NLC) was fabricated from rambutan (Nephelium lappaceum L.) kernel fat stabilized with Tween 80 in this present work. The influence of the Tween 80 concentration (0.025, 0.05, 0.1, 0.2, 0.5 and 1.0wt%) and solidification temperature (5 and 25°C) on the characteristics and stability of the NLC were investigated. The results showed that an increase in the Tween 80 concentration caused decreased zeta-potential (ζ-potential) and particle size (Z-average) with no significant effect on the polydispersity index (PDI). Lipid particles in the NLC at all Tween 80 concentrations had a tendency to grow and the PDI tended to increase due to Ostwald ripening upon storage over 28days. At least 0.2wt% Tween 80 concentrations could be used to stabilize 1wt% rambutan NLC. The solidification temperature affected the microstructure, melting behavior and stability of rambutan NLC. Pre-solidification at 5°C could create stable NLC with monodispersed-spherical lipid particles. Consequently, these stable NLC particles produced from rambutan kernel fat may serve as useful carriers for the delivery of bioactive lipophilic nutraceuticals. Copyright © 2017 Elsevier Inc. All rights reserved.

An Application of X-Ray Fluorescence as Process Analytical Technology (PAT) to Monitor Particle Coating Processes.

PubMed

Nakano, Yoshio; Katakuse, Yoshimitsu; Azechi, Yasutaka

2018-06-01

An attempt to apply X-Ray Fluorescence (XRF) analysis to evaluate small particle coating process as a Process Analytical Technologies (PAT) was made. The XRF analysis was used to monitor coating level in small particle coating process with at-line manner. The small particle coating process usually consists of multiple coating processes. This study was conducted by a simple coating particles prepared by first coating of a model compound (DL-methionine) and second coating by talc on spherical microcrystalline cellulose cores. The particles with two layered coating are enough to demonstrate the small particle coating process. From the result by the small particle coating process, it was found that the XRF signal played different roles, resulting that XRF signals by first coating (layering) and second coating (mask coating) could demonstrate the extent with different mechanisms for the coating process. Furthermore, the particle coating of the different particle size has also been investigated to evaluate size effect of these coating processes. From these results, it was concluded that the XRF could be used as a PAT in monitoring particle coating processes and become powerful tool in pharmaceutical manufacturing.

Spherical Al-substituted ɑ-nickel hydroxide with high tapping density applied in Ni-MH battery

NASA Astrophysics Data System (ADS)

Wu, Xing-Hua; Feng, Qing-Ping; Wang, Man; Huang, Gui-Wen

2016-10-01

Spherical Al-substituted ɑ-Ni(OH)2 with high tapping density are prepared with controlled crystallization method, where the synthesis parameters are previously calculated out according to theoretical analysis. The formation mechanism of Ni(OH)2 particles is analyzed based on theoretical calculation, the optimal conditions for the formation of spherical Al-substituted ɑ-Ni(OH)2 with high tapping density are figured out and a formula indicates the restrictions among main synthesis parameters is derived, which is reference meaningful for the synthesis of commercialized electrode powders. Synthesized by using the calculated parameters, the obtained ɑ-Ni(OH)2 shows uniform spherical morphology, high crystal phase purity and reasonable high tapping density of 1.37 g cm-3, which demonstrates the feasibility of the derived formula. Since the electrical conductivity of the pure Ni(OH)2 is quite low, 5 wt% of CoOOH are coated on the ɑ-Ni(OH)2 surface to improve their electrochemical performances. The synthesized CoOOH coated ɑ-Ni(OH)2 shows relative high specific capacity of 327 mAh g-1 at 0.1 C and acceptable high-rate dischargeability. The simultaneously achieving of high tapping density and high specific capacity in ɑ-Ni(OH)2 makes it own the great potential to be applied in new generation of Ni-MH batteries.

Electromagnetically Tunable Fields

DTIC Science & Technology

2008-07-01

constitutive material properties (electrical permittivity, magnetic permeability, and electrical conductivity) of electromagnetically tunable fluids ( ETFs ... trade -offs and operational perspectives of a dielectric coated spherical inverted-F antenna," accepted for IEEE/URSI Int. Symp. Antennas and Propag

Boundary-element modelling of dynamics in external poroviscoelastic problems

NASA Astrophysics Data System (ADS)

Igumnov, L. A.; Litvinchuk, S. Yu; Ipatov, A. A.; Petrov, A. N.

2018-04-01

A problem of a spherical cavity in porous media is considered. Porous media are assumed to be isotropic poroelastic or isotropic poroviscoelastic. The poroviscoelastic formulation is treated as a combination of Biot’s theory of poroelasticity and elastic-viscoelastic correspondence principle. Such viscoelastic models as Kelvin–Voigt, Standard linear solid, and a model with weakly singular kernel are considered. Boundary field study is employed with the help of the boundary element method. The direct approach is applied. The numerical scheme is based on the collocation method, regularized boundary integral equation, and Radau stepped scheme.

Laser induced spark ignition of methane-oxygen mixtures

NASA Technical Reports Server (NTRS)

Santavicca, D. A.; Ho, C.; Reilly, B. J.; Lee, T.-W.

1991-01-01

Results from an experimental study of laser induced spark ignition of methane-oxygen mixtures are presented. The experiments were conducted at atmospheric pressure and 296 K under laminar pre-mixed and turbulent-incompletely mixed conditions. A pulsed, frequency doubled Nd:YAG laser was used as the ignition source. Laser sparks with energies of 10 mJ and 40 mJ were used, as well as a conventional electrode spark with an effective energy of 6 mJ. Measurements were made of the flame kernel radius as a function of time using pulsed laser shadowgraphy. The initial size of the spark ignited flame kernel was found to correlate reasonably well with breakdown energy as predicted by the Taylor spherical blast wave model. The subsequent growth rate of the flame kernel was found to increase with time from a value less than to a value greater than the adiabatic, unstretched laminar growth rate. This behavior was attributed to the combined effects of flame stretch and an apparent wrinkling of the flame surface due to the extremely rapid acceleration of the flame. The very large laminar flame speed of methane-oxygen mixtures appears to be the dominant factor affecting the growth rate of spark ignited flame kernels, with the mode of ignition having a small effect. The effect of incomplete fuel-oxidizer mixing was found to have a significant effect on the growth rate, one which was greater than could simply be accounted for by the effect of local variations in the equivalence ratio on the local flame speed.

Effect of pH on ionic liquid mediated synthesis of gold nanoparticle using elaiseguineensis (palm oil) kernel extract

NASA Astrophysics Data System (ADS)

Irfan, Muhammad; Ahmad, Tausif; Moniruzzaman, Muhammad; Abdullah, Bawadi

2017-05-01

This study was conducted for microwave assisted synthesis of stable gold nanoparticles (AuNPs) by reduction of chloroauric acid with Elaeis Guineensis (palm oil) kernel (POK) extract which was prepared in aqueous solution of ionic liquid, [EMIM][OAc], 1-Ethyl-3-methylimidazolium acetate. Effect of initial pH of reaction mixture (3.5 - 8.5) was observed on SPR absorbance, maximum wavelength (λmax ) and size distribution of AuNPs. Change of pH of reaction mixture from acidic to basic region resulted in appearance of strong SPR absorption peaks and blue shifting of λmax from 533 nm to 522 nm. TEM analysis revealed the formation of predominantly spherical AuNPs with mean diameter of 8.51 nm. Presence of reducing moieties such as flavonoids, phenolic and carboxylic groups in POK extract was confirmed by FTIR analysis. Colloidal solution of AuNPs was remained stable at room temperature and insignificant difference in zeta value was recorded within experimental tenure of 4 months.

Conceptual design of quadriso particles with europium burnable absorber in HTRS.

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

Talamo, A.; Nuclear Engineering Division

2010-05-18

In High Temperature Reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this study QUADRISO particles are proposed to manage the initial xcess reactivity of High Temperature Reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This echanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the nitialmore » excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, ore eutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic High Temperature Reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.« less

A novel concept of QUADRISO particles. Part II: Utilization for excess reactivity control.

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

Talamo, A.

2010-07-01

In high temperature reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this paper QUADRISO particles are proposed to manage the initial excess reactivity of high temperature reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This mechanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the initialmore » excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, more neutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic high temperature reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.« less

A novel concept of QUADRISO particles : Part II Utilization for excess reactivity control.

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

Talamo, A.

2011-01-01

In high temperature reactors, burnable absorbers are utilized to manage the excess reactivity at the early stage of the fuel cycle. In this paper QUADRISO particles are proposed to manage the initial excess reactivity of high temperature reactors. The QUADRISO concept synergistically couples the decrease of the burnable poison with the decrease of the fissile materials at the fuel particle level. This mechanism is set up by introducing a burnable poison layer around the fuel kernel in ordinary TRISO particles or by mixing the burnable poison with any of the TRISO coated layers. At the beginning of life, the initialmore » excess reactivity is small because some neutrons are absorbed in the burnable poison and they are prevented from entering the fuel kernel. At the end of life, when the absorber is almost depleted, more neutrons stream into the fuel kernel of QUADRISO particles causing fission reactions. The mechanism has been applied to a prismatic high temperature reactor with europium or erbium burnable absorbers, showing a significant reduction in the initial excess reactivity of the core.« less

Analysis of 2-Acetyl-1-Pyrroline in rice by HSSE/GC/MS.

USDA-ARS?s Scientific Manuscript database

An alternative method for the analysis of 2-acetyl-1-pyrroline (2AP) in rice employing stir bar sorptive extraction (Twister™), is described. The Twister stir bar is placed in the headspace of a 20 ml vial containing 1 g rice kernels, 5 ml 0.1 M KOH, 2,2 g NaCl, and a second Teflon™ coated stir bar...

Application of Vector Spherical Harmonics and Kernel Regression to the Computations of OMM Parameters

NASA Astrophysics Data System (ADS)

Marco, F. J.; Martínez, M. J.; López, J. A.

2015-04-01

The high quality of Hipparcos data in position, proper motion, and parallax has allowed for studies about stellar kinematics with the aim of achieving a better physical understanding of our galaxy, based on accurate calculus of the Ogorodnikov-Milne model (OMM) parameters. The use of discrete least squares is the most common adjustment method, but it may lead to errors mainly because of the inhomogeneous spatial distribution of the data. We present an example of the instability of this method using the case of a function given by a linear combination of Legendre polynomials. These polynomials are basic in the use of vector spherical harmonics, which have been used to compute the OMM parameters by several authors, such as Makarov & Murphy, Mignard & Klioner, and Vityazev & Tsvetkov. To overcome the former problem, we propose the use of a mixed method (see Marco et al.) that includes the extension of the functions of residuals to any point on the celestial sphere. The goal is to be able to work with continuous variables in the calculation of the coefficients of the vector spherical harmonic developments with stability and efficiency. We apply this mixed procedure to the study of the kinematics of the stars in our Galaxy, employing the Hipparcos velocity field data to obtain the OMM parameters. Previously, we tested the method by perturbing the Vectorial Spherical Harmonics model as well as the velocity vector field.

Low-cost method for producing extreme ultraviolet lithography optics

DOEpatents

Folta, James A [Livermore, CA; Montcalm, Claude [Fort Collins, CO; Taylor, John S [Livermore, CA; Spiller, Eberhard A [Mt. Kisco, NY

2003-11-21

Spherical and non-spherical optical elements produced by standard optical figuring and polishing techniques are extremely expensive. Such surfaces can be cheaply produced by diamond turning; however, the roughness in the diamond turned surface prevent their use for EUV lithography. These ripples are smoothed with a coating of polyimide before applying a 60 period Mo/Si multilayer to reflect a wavelength of 134 .ANG. and have obtained peak reflectivities close to 63%. The savings in cost are about a factor of 100.

Calculation and experimental study on high-speed impact of heat-resistant coating materials with a meteoric particle

NASA Astrophysics Data System (ADS)

Glazunov, Anatoly; Ishchenko, Aleksandr; Afanas'eva, Svetlana; Belov, Nikolai; Burkin, Viktor; Rogaev, Konstantin; Yugov, Nikolai

2016-01-01

The given article presents the conducted calculation and experimental study on destruction of heat-resistant coating material of an aircraft in the process of high-speed interaction of the steel spherical projectile. The projectile is imitating a meteoric particle. The study was conducted in the wide range of velocities. The mathematical behavioral model of heat-resistant coating under high-speed impact was developed. The interaction of ameteoric particle with an element of the protective structure has especially individual character and depends on impact velocity and angle, materials of the interacting solids.

About properties of ZrO2 thermal protective coatings obtained from spherical powder mixtures

NASA Astrophysics Data System (ADS)

Berdnik, O. B.; Tsareva, I. N.; Tarasenko, Yu P.

2017-05-01

It is developed the technology of high-energy plasma spraying of the zirconium dioxide (ZrO2) thermal protective coating on the basis of ZrO2 tetragonal and cubic phases with the spheroidal grain shape and the columnar substructure, with the total porosity P = 4 %, the hardness HV = 12 GPa, the roughness parameter R a ˜ 6 μm, the thickness 0.3-3 mm. As a sublayer it is used the heat-resistant coating of “Ni-Co-Cr-Al-Y” system with an intermetallic phase composition and the layered microstructure of the grains.

The Infrared & Electro-Optical Systems Handbook. Emerging Systems and Technologies, Volume 8

DTIC Science & Technology

1993-01-01

usually associated with turbulence in the intervening path or to significant nonuniformities in com- position or temperature of the air within the field of...cause beam quality to be less than perfect. Coatings on the mirrors can also be nonuniform , leading to further OPD effects. Resonator misalignment...despite an undesired spherical error). Coatings can be nonuniform in their thickness. This thickness nonuniform - ity is equivalent to a mirror fabrication

The Modularized Software Package ASKI - Full Waveform Inversion Based on Waveform Sensitivity Kernels Utilizing External Seismic Wave Propagation Codes

NASA Astrophysics Data System (ADS)

Schumacher, F.; Friederich, W.

2015-12-01

We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full waveform inversion.

GRACE Mass Flux Measurements of Inland and Marginal Seas from Mascons: Analysis and Validation

NASA Astrophysics Data System (ADS)

Loomis, B.; Luthcke, S. B.; Sabaka, T. J.

2015-12-01

The latest GRACE time-variable gravity mascon solution from the NASA Goddard Space Flight Center (GSFC) applies an optimized set of models and constraints towards the direct measurement of 1-arc-degree global mass flux parameters each month. Separate mascon spatial constraint regions have been defined for the largest inland and marginal seas: Mediterranean Sea, Black Sea, Caspian Sea, Red Sea, and Hudson Bay. The mascon estimation approach, when applied with well-designed constraints, minimizes signal leakage across regional boundaries and eliminates the need for post-processing strategies. These post-processing techniques (e.g. smoothed averaging kernels) are necessary for computing regional mass change from the unconstrained spherical harmonics provided by the GRACE project to reduce the effect of noisy high degree and order terms, but introduce signal leakage into and out of the considered region. These mass signals are also difficult to obtain from altimetry measurements due to the comparatively sparse temperature and salinity data in these regions, which is needed to compute and remove the steric component of sea level variations. We provide new GSFC mascon measurements of these inland and marginal seas and compare to results obtained from kernel-averaged spherical harmonic solutions and steric-corrected altimetry measurements. The relative accuracy of the various solutions is determined by incorporating their output into the set of forward models applied in our processing of the GRACE Level-1B data and analyzing the effect on the inter-satellite range-rate residuals, where a reduction in residuals is a direct validation of improved solution quality.

Thermomechanics of candidate coatings for advanced gas reactor fuels

NASA Astrophysics Data System (ADS)

Nosek, A.; Conzen, J.; Doescher, H.; Martin, C.; Blanchard, J.

2007-09-01

Candidate fuel/coating combinations for an advanced, coated-fuel particle for a gas-cooled fast reactor (GFR) have been evaluated. These all-ceramic fuel forms consist of a fuel kernel made of UC or UN, surrounded with two shells (a buffer and a coating) made of TiC, SiC, ZrC, TiN, or ZrN. These carbides and nitrides are analyzed with finite element models to determine the stresses produced in the micro fuel particles from differential thermal expansion, fission gas release, swelling, and creep during particle fabrication and reactor operation. This study will help determine the feasibility of different fuel and coating combinations and identify the critical loads. The analysis shows that differential thermal expansion of the fuel and coating dictate the amount of stress for changing temperatures (such as during fabrication), and that the coating creep is able to mitigate an otherwise overwhelming amount of stress from fuel swelling. Because fracture is a likely mode of failure, a fracture mechanics study is also included to identify the relative likelihood of catastrophic fracture of the coating and resulting gas release. Overall, the analysis predicts that UN/ZrC is the best thermomechanical fuel/coating combination for mitigating the stress within the new fuel particle, but UN/TiN and UN/ZrN could also be strong candidates if their unknown creep rates are sufficiently large.

Improved Small-Particle Powders for Plasma Spraying

NASA Technical Reports Server (NTRS)

Nguyen, QuynhGiao, N.; Miller, Robert A.; Leissler, George W.

2005-01-01

Improved small-particle powders and powder-processing conditions have been developed for use in plasma spray deposition of thermal-barrier and environmental barrier coatings. Heretofore, plasma-sprayed coatings have typically ranged in thickness from 125 to 1,800 micrometers. As explained below, the improved powders make it possible to ensure complete coverage of substrates at unprecedently small thicknesses of the order of 25 micrometers. Plasma spraying involves feeding a powder into a hot, high-velocity plasma jet. The individual powder particles melt in the plasma jet as they are propelled towards a substrate, upon which they splat to build up a coating. In some cases, multiple coating layers are required. The size range of the powder particles necessarily dictates the minimum thickness of a coating layer needed to obtain uniform or complete coverage. Heretofore, powder particle sizes have typically ranged from 40 to 70 micrometers; as a result, the minimum thickness of a coating layer for complete coverage has been about 75 micrometers. In some applications, thinner coatings or thinner coating layers are desirable. In principle, one can reduce the minimum complete-coverage thickness of a layer by using smaller powder particles. However, until now, when powder particle sizes have been reduced, the powders have exhibited a tendency to cake, clogging powder feeder mechanisms and feed lines. Hence, the main problem is one of synthesizing smaller-particle powders having desirable flow properties. The problem is solved by use of a process that begins with a spray-drying subprocess to produce spherical powder particles having diameters of less than 30 micrometers. (Spherical-particle powders have the best flow properties.) The powder is then passed several times through a commercial sifter with a mesh to separate particles having diameters less than 15 micrometers. The resulting fine, flowable powder is passed through a commercial fluidized bed powder feeder into a plasma spray jet.

Facile hydrothermal synthesis of carbon-coated cobalt ferrite spherical nanoparticles as a potential negative electrode for flexible supercapattery.

PubMed

Sankar, Kalimuthu Vijaya; Shanmugapriya, Sathyanarayanan; Surendran, Subramani; Jun, Seong Chan; Selvan, Ramakrishnan Kalai

2018-03-01

Battery type electrodes would replace the currently available pseudocapacitive electrodes by the cause of high energy density and long discharge time. In this regard, battery type carbon coated CoFe 2 O 4 spherical nanoparticles is prepared by the facile hydrothermal method and tested as the possible negative electrode for supercapattery applications. The phase purity, electronic states of elements, and the presence of carbon is inferred through various sophisticated techniques. The calculated surface area of CoFe 2 O 4 and carbon coated CoFe 2 O 4 are found to be 9 and 26 m 2  g -1 , respectively. The morphological analysis confirms the formation of uniform CoFe 2 O 4 nanospheres (∼25 nm) with a thin layer of carbon coating (∼2 nm). The amorphous carbon coating over CoFe 2 O 4 nanosphere is identified via high-resolution transmission electron microscope. The observed peak and plateau regions in the cyclic voltammogram and galvanostatic charge/discharge curves reveals the battery-type charge storage behaviour of the material. The carbon coated CoFe 2 O 4 delivers the maximum length capacitance of 9.9 F m -1 at 1 mV s -1 with a useful lifespan over 5000 cycles. The electrochemical impedance spectroscopy reveals that the carbon-coated CoFe 2 O 4 delivers the low charge transfer resistance than CoFe 2 O 4 . Further, the fabricated supercapattery provides the energy density of 160 × 10 -8  Wh cm -1 at a power density of 67.2 μW cm -1 . As well as, the device shows 93% of coulombic efficiency and 75% of the specific capacitance retention over 11,000 cycles. Overall, it is believed that the carbon-coated CoFe 2 O 4 can serve as a good candidate for flexible supercapatteries. Copyright © 2017 Elsevier Inc. All rights reserved.

Numerical modeling of the 3D dynamics of ultrasound contrast agent microbubbles using the boundary integral method

NASA Astrophysics Data System (ADS)

Wang, Qianxi; Manmi, Kawa; Calvisi, Michael L.

2015-02-01

Ultrasound contrast agents (UCAs) are microbubbles stabilized with a shell typically of lipid, polymer, or protein and are emerging as a unique tool for noninvasive therapies ranging from gene delivery to tumor ablation. While various models have been developed to describe the spherical oscillations of contrast agents, the treatment of nonspherical behavior has received less attention. However, the nonspherical dynamics of contrast agents are thought to play an important role in therapeutic applications, for example, enhancing the uptake of therapeutic agents across cell membranes and tissue interfaces, and causing tissue ablation. In this paper, a model for nonspherical contrast agent dynamics based on the boundary integral method is described. The effects of the encapsulating shell are approximated by adapting Hoff's model for thin-shell, spherical contrast agents. A high-quality mesh of the bubble surface is maintained by implementing a hybrid approach of the Lagrangian method and elastic mesh technique. The numerical model agrees well with a modified Rayleigh-Plesset equation for encapsulated spherical bubbles. Numerical analyses of the dynamics of UCAs in an infinite liquid and near a rigid wall are performed in parameter regimes of clinical relevance. The oscillation amplitude and period decrease significantly due to the coating. A bubble jet forms when the amplitude of ultrasound is sufficiently large, as occurs for bubbles without a coating; however, the threshold amplitude required to incite jetting increases due to the coating. When a UCA is near a rigid boundary subject to acoustic forcing, the jet is directed towards the wall if the acoustic wave propagates perpendicular to the boundary. When the acoustic wave propagates parallel to the rigid boundary, the jet direction has components both along the wave direction and towards the boundary that depend mainly on the dimensionless standoff distance of the bubble from the boundary. In all cases, the jet directions for the coated and uncoated bubble are similar but the jet width and jet velocity are smaller for a coated bubble. The effects of shell thickness and shell viscosity are analyzed and determined to affect the bubble dynamics, including jet development.

Influence of thin-film metallic glass coating on fatigue behavior of bulk metallic glass: Experiments and finite element modeling

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

Yu, Chia-Chi; Chu, Jinn P.; Jia, Haoling

In this paper, a coating of the Zr-based thin-film metallic glass (TFMG) was deposited on the Zr 50Cu 30Al 10Ni 10 bulk metallic glass (BMG) to investigate shear-band evolution under four-point-bend fatigue testing. The fatigue endurance-limit of the TFMG-coated samples is ~ 33% higher than that of the BMG. The results of finite-element modeling (FEM) revealed a delay in the shear-band nucleation and propagation in TFMG-coated samples under applied cyclic-loading. The FEM study of spherical indentation showed that the redistribution of stress by the TFMG coating prevents localized shear-banding in the BMG substrate. Finally, the enhanced fatigue characteristics of themore » BMG substrates can be attributed to the TFMG coatings retarding shear-band initiation at defects on the surface of the BMG.« less

Influence of thin-film metallic glass coating on fatigue behavior of bulk metallic glass: Experiments and finite element modeling

DOE PAGES

Yu, Chia-Chi; Chu, Jinn P.; Jia, Haoling; ...

2017-03-21

In this paper, a coating of the Zr-based thin-film metallic glass (TFMG) was deposited on the Zr 50Cu 30Al 10Ni 10 bulk metallic glass (BMG) to investigate shear-band evolution under four-point-bend fatigue testing. The fatigue endurance-limit of the TFMG-coated samples is ~ 33% higher than that of the BMG. The results of finite-element modeling (FEM) revealed a delay in the shear-band nucleation and propagation in TFMG-coated samples under applied cyclic-loading. The FEM study of spherical indentation showed that the redistribution of stress by the TFMG coating prevents localized shear-banding in the BMG substrate. Finally, the enhanced fatigue characteristics of themore » BMG substrates can be attributed to the TFMG coatings retarding shear-band initiation at defects on the surface of the BMG.« less

Glass frits coated with silver nanoparticles for silicon solar cells

NASA Astrophysics Data System (ADS)

Li, Yingfen; Gan, Weiping; Zhou, Jian; Li, Biyuan

2015-06-01

Glass frits coated with silver nanoparticles were prepared by electroless plating. Gum Arabic (GA) was used as the activating agent of glass frits without the assistance of stannous chloride or palladium chloride. The silver-coated glass frits prepared with different GA dosages were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The characterization results indicated that silver-coated glass frits had the structures of both glass and silver. Spherical silver nanoparticles were distributed on the glass frits evenly. The density and particle size of silver nanoparticles on the glass frits can be controlled by adjusting the GA dosage. The silver-coated glass frits were applied to silver pastes to act as both the densification promoter and silver crystallite formation aid in the silver electrodes. The prepared silver-coated glass frits can improve the photovoltaic performances of solar cells.

Sea buckthorn (Hippophae rhamnoides) proanthocyanidins inhibit in vitro enzymatic hydrolysis of protein.

PubMed

Arimboor, Ranjith; Arumughan, C

2011-08-01

Interactions of phenolics with other food constituents and digestive enzymes are likely to have interference with the digestion and bioavailability of food and phenolics. In this study the effect of sea buckthorn proanthocyanidins on in vitro digestion of protein was evaluated. Optimization of the extraction conditions showed that maximum recovery of sea buckthorn proanthocyanidins was obtained with acidified acetone; water mixture (60% to 70%, v/v). Crude proanthocyanidin extracts thus prepared were purified using sephadex gel column chromatography and their average degree of polymerization and the effects on enzymatic hydrolysis of bovine serum albumin as influenced by their protein precipitation capacities were studied. Average degree of polymerization of proanthocyanidins in berry pulp, kernel, seed coat, and leaves was 7.4, 5.6, 8.2, and 10.6, respectively. The EC50 values for the protein precipitation by the PA of berry pulp, kernel seed coat, and leaves were 44.2, 44.1, 65.8, and 39.8 μg, respectively. Relative enzymatic hydrolysis of the protein-proanthocyanidin complexes was 44.1% to 60.3% for pepsin and 57.5% to 67.7% for trypsin. Interactions of sea buckthorn proanthocyanidins with food proteins and digestive enzymes might alter the protein digestibility and phenolic bioavailabilty. © 2011 Institute of Food Technologists®

Effects of packaging materials on storage quality of peanut kernels

PubMed Central

Fu, Xiaoji; Xing, Shengping; Xiong, Huiwei; Min, Hua; Zhu, Xuejing; He, Jialin; Mu, Honglei

2018-01-01

In order to obtain optimum packaging materials for peanut kernels, the effects of four types of packaging materials on peanut storage quality (coat color, acid value, germination rate, relative damage, and prevention of aflatoxin contamination) were examined. The results showed that packaging materials had a major influence on peanut storage quality indexes. The color of the peanut seed coat packaged in the polyester/aluminum/polyamide/polyethylene (PET/AL/PA/PE) composite film bag did not change significantly during the storage period. Color deterioration was slower with polyamide/polyethylene (PA/PE) packaging materials than with polyethylene (PE) film bags and was slower in PE bags than in the woven bags. The use of PET/AL/PA/PE and PA/PE bags maintained peanut quality and freshness for more than one year and both package types resulted in better germination rates. There were significant differences between the four types of packaging materials in terms of controlling insect pests. The peanuts packaged in the highly permeable woven bags suffered serious invasion from insect pests, while both PET/AL/PA/PE and PA/PE bags effectively prevented insect infection. Peanuts stored in PET/AL/PA/PE and PA/PE bags were also better at preventing and controlling aflatoxin contamination. PMID:29518085

Method to produce large, uniform hollow spherical shells

DOEpatents

Hendricks, C.D.

1983-09-26

The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.

Simulation study of depositing the carbon film on nanoparticles in the magnetized methane plasma

NASA Astrophysics Data System (ADS)

Mohammadzadeh, Hosein; Pourali, Nima; Ebadi, Zahra

2018-03-01

Plasma coating of nanoparticles in low-temperature magnetized methane plasma is studied by a simulation approach. To this end, by using the global model, the electron temperature and concentration of different species considered in this plasma are determined in the center of a capacitively coupled discharge. Then, the plasma-wall transition region in the presence of an oblique magnetic field is simulated by the multi-component fluid description. Nanoparticles with different radii are injected into the transition region and surface deposition and heating models, as well as dynamics and charging models, are employed to examine the coating process. The results of the simulation show that the non-spherical growth of nanoparticles is affected by the presence of the magnetic field, as with passing time, an oscillating increase is seen in the thickness of the film deposited on nanoparticles. Also, it is shown that the uniformity of the deposited film is dependent on the rotation velocity of nanoparticles. Generally, the obtained results imply that the sphericity of nanoparticles and uniformity of the film coated on them are controllable by the magnitude and orientation of the magnetic field.

Water window imaging x ray microscope

NASA Technical Reports Server (NTRS)

Hoover, Richard B. (Inventor)

1992-01-01

A high resolution x ray microscope for imaging microscopic structures within biological specimens has an optical system including a highly polished primary and secondary mirror coated with identical multilayer coatings, the mirrors acting at normal incidence. The coatings have a high reflectivity in the narrow wave bandpass between 23.3 and 43.7 angstroms and have low reflectivity outside of this range. The primary mirror has a spherical concave surface and the secondary mirror has a spherical convex surface. The radii of the mirrors are concentric about a common center of curvature on the optical axis of the microscope extending from the object focal plane to the image focal plane. The primary mirror has an annular configuration with a central aperture and the secondary mirror is positioned between the primary mirror and the center of curvature for reflecting radiation through the aperture to a detector. An x ray filter is mounted at the stage end of the microscope, and film sensitive to x rays in the desired band width is mounted in a camera at the image plane of the optical system. The microscope is mounted within a vacuum chamber for minimizing the absorption of x rays in air from a source through the microscope.

Optimization and design of pigments for heat-insulating coatings

NASA Astrophysics Data System (ADS)

Wang, Guang-Hai; Zhang, Yue

2010-12-01

This paper reports that heat insulating property of infrared reflective coatings is obtained through the use of pigments which diffuse near-infrared thermal radiation. Suitable structure and size distribution of pigments would attain maximum diffuse infrared radiation and reduce the pigment volume concentration required. The optimum structure and size range of pigments for reflective infrared coatings are studied by using Kubelka—Munk theory, Mie model and independent scattering approximation. Taking titania particle as the pigment embedded in an inorganic coating, the computational results show that core-shell particles present excellent scattering ability, more so than solid and hollow spherical particles. The optimum radius range of core-shell particles is around 0.3 ~ 1.6 μm. Furthermore, the influence of shell thickness on optical parameters of the coating is also obvious and the optimal thickness of shell is 100-300 nm.

Surface Enhancement For Optical Plastics

NASA Astrophysics Data System (ADS)

Masso, Jon D.

1988-07-01

Optical plastics can be molded or cast to replicate traditional spherical and aspheric lenses. It is possible to obtain good optical quality, but often it is necessary or desirable to enhance the surface characteristics in a variety of ways. These include improving the abrasion resistance, chemical resistance, the addition of anti-fog, or anti-static characteristics, applying electrically conductive coatings, and applying coatings or selective absorbers for light and color control. Coatings may be entirely organic or organo-silanes applied by dipping or spinning. All dielectric coatings such as quartz abrasion resistant coatings or multilayer dielectric coatings for reflection reduction or enhancement may be applied by vacuum vapor deposition. This paper discusses a number of these coatings and surface treatments. The paper describes their characteristics and includes discussions of their durability and environmental stability. The adhesion of coatings to plastic substrate depends on the specific substrate and coating materials. Pretreatments or primers are used to promote good coating adhesion. A coating used for one purpose will generally affect other properties of the plastic and trade-offs are sometimes required. A description is given of several test methods which have been found useful in evaluating the quality of the various coatings.

Plasma coating of nanoparticles in the presence of an external electric field

NASA Astrophysics Data System (ADS)

Ebadi, Zahra; Pourali, Nima; Mohammadzadeh, Hosein

2018-04-01

Film deposition onto nanoparticles by low-pressure plasma in the presence of an external electric field is studied numerically. The plasma discharge fluid model along with surface deposition and heating models for nanoparticles, as well as a dynamics model considering the motion of nanoparticles, are employed for this study. The results of the simulation show that applying external field during the process increases the uniformity of the film deposited onto nanoparticles and leads to that nanoparticles grow in a spherical shape. Increase in film uniformity and particles sphericity is related to particle dynamics that is controlled by parameters of the external field like frequency and amplitude. The results of this work can be helpful to produce spherical core-shell nanoparticles in nanomaterial industry.

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

Stampfl, Sibylle; Stampfl, Ulrike; Bellemann, Nadine

The objective of this study was to evaluate inflammatory response and recanalization after embolization with a new spherical embolic agent based on a core and shell design with a hydrogel core of polymethylmethacrylate (PMMA) and a Polyzene-F nanoscale coating in a porcine kidney model. Thirty-six minipigs were enrolled for superselective renal embolization. Polyzene-F-coated PMMA particles and uncoated PMMA particles with a diameter of 300-600 {mu}m were used. Either 4 or 12 weeks post-embolization, arteriography of the embolized kidneys was performed and then compared with pre- and immediate post-embolization arteriograms using a specific recanalization score to determine the extent of recanalization.more » Using a microscopic inflammation score (Banff classification), the embolized organs were examined for local inflammatory effects which occurred in response to the embolic agent. In Polyzene-F-coated particles, the Banff classification showed an average inflammation score of 0.26 {+-} 0.58 at 4 weeks and of 0.08 {+-} 0.28 at 12 weeks. In uncoated particles, the Banff score measured 0.37 {+-} 0.6 at 4 weeks, which was higher, but without a statistically significant difference. According to the recanalization score used in this study, mild angiographic recanalization was evident in all groups, without statistically significant differences (3.0 {+-} 0.71 in coated particles, 3.09 {+-} 0.81 in uncoated particles; p = 0.74). We conclude that both uncoated hydrogel particles and Polyzene-F-coated embolic agents triggered virtually no inflammatory response and effectively occluded target arteries. This study demonstrates good biocompatibility of the new embolic material. As in other spherical embolic agents, recanalization can occur to some degree.« less

TiC-Fe-Based Composite Coating Prepared by Self-Propagating High-Temperature Synthesis

NASA Astrophysics Data System (ADS)

He, Shen; Fan, Xi'an; Chang, Qingming; Xiao, Lixiang

2017-06-01

TiC-Fe-based composite coatings were prepared in situ by self-propagating high-temperature synthesis combined with vacuum expendable pattern casting process. The band-like TiC phase embedded in a continuous Fe binder. There were no obvious defects and impurities at the interface between coatings and matrices. Fe presented consecutively in the coating zones and substrate zones without interruption and the microhardness in the cross-sectional area of the coating-matrix reduces continuously from the coating to the matrix area, indicating a good metallurgical bonding between the coatings and matrices. The effect of casting temperature on the microstructure and hardness of TiC-Fe-based composite coating was investigated in detail. The TiC particles formed at low casting temperature were nearly spherical in shape, and the size of TiC particles increased with increasing casting temperature due to more agglomeration. The hardness of the coatings increased first and then decreased with increasing casting temperature, and reached the highest value of 68 HRC when the casting temperature was 1773 K (1500 °C), which was twice more than that of the matrix.

Hollow lensing duct

DOEpatents

Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

2000-01-01

A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

Development of optical WGM resonators for biosensors

NASA Astrophysics Data System (ADS)

Brice, I.; Pirktina, A.; Ubele, A.; Grundsteins, K.; Atvars, A.; Viter, R.; Alnis, J.

2017-12-01

Whispering Gallery Mode (WGM) resonators are very sensitive to nanoparticles attaching to the surface. We simulate this process using COMSOL Wave Optics module. Our spherical WGM resonators are produced by melting a tip of an optical fiber and we measure optical Q factors in the 105 range. Molecular oxygen lines of the air in the 760 nm region are used as reference markers when looking for the shifts of the WGM resonance lines. We demonstrate WGM microresonator surface coating with a layer of ZnO nanorods as well as with polystyrene microspheres. Coatings produce increased contact surface. Additional layer of antigens/antibodies will be coated to make high-specificity biosensors.

Space Radiation Detector with Spherical Geometry

NASA Technical Reports Server (NTRS)

Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

2011-01-01

A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

Space Radiation Detector with Spherical Geometry

NASA Technical Reports Server (NTRS)

Wrbanek, John D. (Inventor); Fralick, Gustave C. (Inventor); Wrbanek, Susan Y. (Inventor)

2012-01-01

A particle detector is provided, the particle detector including a spherical Cherenkov detector, and at least one pair of detector stacks. In an embodiment of the invention, the Cherenkov detector includes a sphere of ultraviolet transparent material, coated by an ultraviolet reflecting material that has at least one open port. The Cherenkov detector further includes at least one photodetector configured to detect ultraviolet light emitted from a particle within the sphere. In an embodiment of the invention, each detector stack includes one or more detectors configured to detect a particle traversing the sphere.

AGR-1 Post Irradiation Examination Final Report

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

Demkowicz, Paul Andrew

The post-irradiation examination (PIE) of the Advanced Gas Reactor (AGR)-1 experiment was a multi-year, collaborative effort between Idaho National Laboratory (INL) and Oak Ridge National Laboratory (ORNL) to study the performance of UCO (uranium carbide, uranium oxide) tristructural isotropic (TRISO) coated particle fuel fabricated in the U.S. and irradiated at the Advanced Test Reactor at INL to a peak burnup of 19.6% fissions per initial metal atom. This work involved a broad array of experiments and analyses to evaluate the level of fission product retention by the fuel particles and compacts (both during irradiation and during post-irradiation heating tests tomore » simulate reactor accident conditions), investigate the kernel and coating layer morphology evolution and the causes of coating failure, and explore the migration of fission products through the coating layers. The results have generally confirmed the excellent performance of the AGR-1 fuel, first indicated during the irradiation by the observation of zero TRISO coated particle failures out of 298,000 particles in the experiment. Overall release of fission products was determined by PIE to have been relatively low during the irradiation. A significant finding was the extremely low levels of cesium released through intact coatings. This was true both during the irradiation and during post-irradiation heating tests to temperatures as high as 1800°C. Post-irradiation safety test fuel performance was generally excellent. Silver release from the particles and compacts during irradiation was often very high. Extensive microanalysis of fuel particles was performed after irradiation and after high-temperature safety testing. The results of particle microanalysis indicate that the UCO fuel is effective at controlling the oxygen partial pressure within the particle and limiting kernel migration. Post-irradiation examination has provided the final body of data that speaks to the quality of the AGR-1 fuel, building on the as-fabricated fuel characterization and irradiation data. In addition to the extensive volume of results generated, the work also resulted in a number of novel analysis techniques and lessons learned that are being applied to the examination of fuel from subsequent TRISO fuel irradiations. This report provides a summary of the results obtained as part of the AGR-1 PIE campaign over its approximately 5-year duration.« less

The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

NASA Astrophysics Data System (ADS)

Jiang, S. T.; Zhang, J.; Shun, S. Z.; Chen, M. F.

2016-12-01

To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO3).4H2O and 0.06 mol/L NH4H2PO4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg2+, F- ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with completely uniform growth was obtained on the Mg-Zn-Zr alloy surface with its thickness reaching about 120 μm.

Evaluation of gravitational curvatures of a tesseroid in spherical integral kernels

NASA Astrophysics Data System (ADS)

Deng, Xiao-Le; Shen, Wen-Bin

2018-04-01

Proper understanding of how the Earth's mass distributions and redistributions influence the Earth's gravity field-related functionals is crucial for numerous applications in geodesy, geophysics and related geosciences. Calculations of the gravitational curvatures (GC) have been proposed in geodesy in recent years. In view of future satellite missions, the sixth-order developments of the gradients are becoming requisite. In this paper, a set of 3D integral GC formulas of a tesseroid mass body have been provided by spherical integral kernels in the spatial domain. Based on the Taylor series expansion approach, the numerical expressions of the 3D GC formulas are provided up to sixth order. Moreover, numerical experiments demonstrate the correctness of the 3D Taylor series approach for the GC formulas with order as high as sixth order. Analogous to other gravitational effects (e.g., gravitational potential, gravity vector, gravity gradient tensor), numerically it is found that there exist the very-near-area problem and polar singularity problem in the GC east-east-radial, north-north-radial and radial-radial-radial components in spatial domain, and compared to the other gravitational effects, the relative approximation errors of the GC components are larger due to not only the influence of the geocentric distance but also the influence of the latitude. This study shows that the magnitude of each term for the nonzero GC functionals by a grid resolution 15^' } } × 15^' }} at GOCE satellite height can reach of about 10^{-16} m^{-1} s2 for zero order, 10^{-24 } or 10^{-23} m^{-1} s2 for second order, 10^{-29} m^{-1} s2 for fourth order and 10^{-35} or 10^{-34} m^{-1} s2 for sixth order, respectively.

Functionalized mesoporous silica nanoparticles for oral delivery of budesonide

NASA Astrophysics Data System (ADS)

Yoncheva, K.; Popova, M.; Szegedi, A.; Mihaly, J.; Tzankov, B.; Lambov, N.; Konstantinov, S.; Tzankova, V.; Pessina, F.; Valoti, M.

2014-03-01

Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of the nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide.

Ultrasonic irradiation and its application for improving the corrosion resistance of phosphate coatings on aluminum alloys.

PubMed

Sheng, Minqi; Wang, Chao; Zhong, Qingdong; Wei, Yinyin; Wang, Yi

2010-01-01

In this paper, ultrasonic irradiation was utilized for improving the corrosion resistance of phosphate coatings on aluminum alloys. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effect of ultrasonic irradiation on the corrosion resistance of phosphate coatings was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). Various effects of the addition of Nd(2)O(3) in phosphating bath on the performance of the coatings were also investigated. Results show that the composition of phosphate coating were Zn(3)(PO(4))(2).4H(2)O(hopeite) and Zn crystals. The phosphate coatings became denser with fewer microscopic holes by utilizing ultrasonic irradiation treatment. The addition of Nd(2)O(3) reduced the crystallinity of the coatings, with the additional result that the crystallites were increasingly nubby and spherical. The corrosion resistance of the coatings was also significantly improved by ultrasonic irradiation treatment; both the anodic and cathodic processes of corrosion taking place on the aluminum alloy substrate were suppressed consequently. In addition, the electrochemical impedance of the coatings was also increased by utilizing ultrasonic irradiation treatment compared with traditional treatment.

Electron Microscopic Evaluation and Fission Product Identification of Irradiated TRISO Coated Particles from the AGR-1 Experiment: A Preliminary Review

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

IJ van Rooyen; DE Janney; BD Miller

2014-05-01

Post-irradiation examination of coated particle fuel from the AGR-1 experiment is in progress at Idaho National Laboratory and Oak Ridge National Laboratory. In this paper a brief summary of results from characterization of microstructures in the coating layers of selected irradiated fuel particles with burnup of 11.3% and 19.3% FIMA will be given. The main objectives of the characterization were to study irradiation effects, fuel kernel porosity, layer debonding, layer degradation or corrosion, fission-product precipitation, grain sizes, and transport of fission products from the kernels across the TRISO layers. Characterization techniques such as scanning electron microscopy, transmission electron microscopy, energymore » dispersive spectroscopy, and wavelength dispersive spectroscopy were used. A new approach to microscopic quantification of fission-product precipitates is also briefly demonstrated. Microstructural characterization focused on fission-product precipitates in the SiC-IPyC interface, the SiC layer and the fuel-buffer interlayer. The results provide significant new insights into mechanisms of fission-product transport. Although Pd-rich precipitates were identified at the SiC-IPyC interlayer, no significant SiC-layer thinning was observed for the particles investigated. Characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates with significantly higher concentrations of Pd and U. Different approaches to resolving this problem are discussed. An initial hypothesis is provided to explain fission-product precipitate compositions and locations. No SiC phase transformations were observed and no debonding of the SiC-IPyC interlayer as a result of irradiation was observed for the samples investigated. Lessons learned from the post-irradiation examination are described and future actions are recommended.« less

Hydrophilic-impermeable modified polyethylene terephthalate for selective endothelialization

NASA Astrophysics Data System (ADS)

Chetouane, D.; Fafet, J. F.; Barbet, R.; Dieval, F.

2017-10-01

The aim of this study was to create a modified polyethylene terephthalate (PET) responding to vascular implants’ requirements, mainly with a surface promoting selective endothelialization. The surface alteration was carried out by hydrophilic functionalization in an alkaline solution with the presence of specific surfactant (TA). The carboxylic groups resulting from this reaction were quantified by colorimetric titration using bleu toluidine O dye (TBO). A single-sided coating process was then optimized to cover the PET surface by micro spherical structures’ polymeric layer. This coating provided to the PET surface high impermeability to the water under a pressure of 120 mmHg and enhanced its hydrophilic property. This spherical topography reduced the adhesion of Mesenchymal Stem Cells (MSC) by 37% and inhibited their proliferation after 3 days by 50%. The hydrophilic functionalized PET (PET-TA) surface decreased the MSC adhesion by 50% and promoted HUVEC attachment with a number twice more important than the number of HUVEC adhered onto non treated-PET.

Design of Polymer-Grafted Particles for Biocompatability

NASA Astrophysics Data System (ADS)

Trombly, David; Ganesan, Venkat

2009-03-01

Drug designers often coat drug particles with grafted polymers in order to introduce a net repulsion between the particles and blood proteins. This net repulsion results from the energy cost of compressing grafted chains on approach of proteins. It thus overcomes the Van Der Waals attraction between drug and protein which would otherwise cause particle-protein agglomeration and ultimately thrombosis. This study proposes to develop a fundamental understanding of the role of different features in controlling the efficacy of the grafted layers. We address this issue by developing a framework to predict the interactions between a polymer-coated spherical particle and a bare spherical particle. In order to fully capture the two-sphere system, a numerical solution of polymer mean field theory is used in a bispherical coordinate system. Results for protein-particle interaction energies for different design parameters will be presented. For biological applications, polyethylene glycol is often used as the grafted polymer. The unique properties of this molecule will be accounted for using the n-cluster model.

β-structure of the coat protein subunits in spherical particles generated by tobacco mosaic virus thermal denaturation.

PubMed

Dobrov, Evgeny N; Nikitin, Nikolai A; Trifonova, Ekaterina A; Parshina, Evgenia Yu; Makarov, Valentin V; Maksimov, George V; Karpova, Olga V; Atabekov, Joseph G

2014-01-01

Conversion of the rod-like tobacco mosaic virus (TMV) virions into "ball-like particles" by thermal denaturation at 90-98 °C had been described by R.G. Hart in 1956. We have reported recently that spherical particles (SPs) generated by thermal denaturation of TMV at 94-98 °C were highly stable, RNA-free, and water-insoluble. The SPs were uniform in shape but varied widely in size (53-800 nm), which depended on the virus concentration. Here, we describe some structural characteristics of SPs using circular dichroism, fluorescence spectroscopy, and Raman spectroscopy. It was found that the structure of SPs protein differs strongly from that of the native TMV and is characterized by coat protein subunits transition from mainly (about 50%) α-helical structure to a structure with low content of α-helices and a significant fraction of β-sheets. The SPs demonstrate strong reaction with thioflavin T suggesting the formation of amyloid-like structures.

[Preparation and Photocatalytic Properties of Supported TiO2 Photocatalytic Material].

PubMed

Guo, Yu; Jin, Yu-jia; Wu, Hong-mei; Li, Dong-xin

2015-06-01

Titanium dioxide (TiO2) supported on spherical alumina substrate was prepared by using sol-gel method combined with dip-coating process. The surface morphology and structure of the synthesized samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) pattern. The results show that the morphology of the supported TiO2 composite material was obviously different from that of the original support. It reveals a layer formed by anatase TiO2 nanoparticles of 10-20 nm was deposited on the alumina substrate. Energy dispersive X-ray spectroscopy (EDX) analyses on the spherical alumina substrate and the resulting TiO2 composite catalyst were performed to determine the TiO2 loading content in the samples. It indicates that the TiO2 loading content on alumina substrate could be effectively increased by increasing the times of dip-coating alumina support in TiO2 sol. When dip-coating times increased to 5, the TiO2 loading content increased from 3.8 Wt. % to 15.7 Wt. %. In addition, the photocatalytic performances of the supported TiO2 materials prepared by different dip-coating times have been investigated by degrading methylene blue. It was found that the surface morphology of the supported TiO2 material was not only improved, but also the photocatalytic activity could be promoted significantly by increasing the dip-coating times. When the alumina substrate was dip-coated in TiO2 sol from 1 to 4 times, the degradation rate of methylene blue increased from 40% to 83.1%. However, after dip-coating the alumina support in TiO2 sol for 5 times, the degradation of methylene blue was only up to 85.6%. This indicates that the photocatalytic activity increased slowly when the TiO2 content in the supported catalyst was up to some extent. It is attributed to the continuous dip-coating resulted in less opportunities and weak intensity of illumination for the TiO2 nano-particles that under lower layer. The photocatalytic activity was relatively stable after repeated use of the supported TiO2 material for 5 times.

In vitro and in vivo antimicrobial activities of seeds of Caesalpinia bonduc (Lin.) Roxb.

PubMed

Arif, Tasleem; Mandal, T K; Kumar, Naresh; Bhosale, J D; Hole, Archana; Sharma, G L; Padhi, M M; Lavekar, G S; Dabur, Rajesh

2009-05-04

Caesalpinia bonduc (Lin.) Roxb. is a known drug in Ayurveda to treat various diseases specifically tumors, cysts and cystic fibrosis (CF). The aim of this study was to assess in vitro as well as in vivo antimicrobial activity of Caesalpinia bonduc seeds. The in vitro antimicrobial activities of seed coat and seed kernel extracts were investigated by microbroth dilution assay. In vivo activities of hydro-alcoholic extracts were investigated in rat models of chronic Pseudomonas aeruginosa pneumonia mimicking that in patients with cystic fibrosis. Various extracts of plant seeds exhibited in vitro antimicrobial activities in a range of 22-350 microg/ml. The extracts also showed activity against methicillin resistant (MR) Staphylococcus aureus and ampicillin resistant (AR) Pseudomonas aeruginosa as in the sensitive strains. In rat model of chronic Pseudomonas aeruginosa pneumonia, hydro-alcoholic extracts of Caesalpinia bonduc seed kernel (CBSK) and Caesalpinia bonduc seed coat (CBSC) were injected subcutaneously in the test groups of animals. The control groups were treated with cortisone and saline. Two weeks after challenge with Pseudomonas aeruginosa, the CBSK treated animals showed a significant bacterial clearance from the lungs (P<0.04) and less severe incidence of lung abscess (P<0.05). Results showed that Caesalpinia bonduc may have the potential to be promising natural medicine, with other forms of treatments, for CF patients with chronic Pseudomonas aeruginosa lung infections.

Core-shell monodisperse spherical mSiO2/Gd2O3:Eu3+@mSiO2 particles as potential multifunctional theranostic agents

NASA Astrophysics Data System (ADS)

Eurov, Daniil A.; Kurdyukov, Dmitry A.; Kirilenko, Demid A.; Kukushkina, Julia A.; Nashchekin, Alexei V.; Smirnov, Alexander N.; Golubev, Valery G.

2015-02-01

Core-shell nanoparticles with diameters in the range 100-500 nm have been synthesized as monodisperse spherical mesoporous (pore diameter 3 nm) silica particles with size deviation of less than 4 %, filled with gadolinium and europium oxides and coated with a mesoporous silica shell. It is shown that the melt technique developed for filling with gadolinium and europium oxides provides a nearly maximum filling of mesopores in a single-run impregnation, with gadolinium and europium uniformly distributed within the particles and forming no bulk oxides on their surface. The coating with a shell does not impair the monodispersity and causes no coagulation. The coating technique enables controlled variation of the shell thickness within the range 5-100 % relative to the core diameter. The thus produced nanoparticles are easily dispersed in water, have large specific surface area (300 m2 g-1) and pore volume (0.3 cm3 g-1), and are bright solid phosphor with superior stability in aqueous media. The core-shell structured particles can be potentially used for cancer treatment as a therapeutic agent (gadolinium neutron-capture therapy and drug delivery system) and, simultaneously, as a multimodal diagnostic tool (fluorescence and magnetic resonance imaging), thereby serving as a multifunctional theranostic agent.

Background field removal using a region adaptive kernel for quantitative susceptibility mapping of human brain

NASA Astrophysics Data System (ADS)

Fang, Jinsheng; Bao, Lijun; Li, Xu; van Zijl, Peter C. M.; Chen, Zhong

2017-08-01

Background field removal is an important MR phase preprocessing step for quantitative susceptibility mapping (QSM). It separates the local field induced by tissue magnetic susceptibility sources from the background field generated by sources outside a region of interest, e.g. brain, such as air-tissue interface. In the vicinity of air-tissue boundary, e.g. skull and paranasal sinuses, where large susceptibility variations exist, present background field removal methods are usually insufficient and these regions often need to be excluded by brain mask erosion at the expense of losing information of local field and thus susceptibility measures in these regions. In this paper, we propose an extension to the variable-kernel sophisticated harmonic artifact reduction for phase data (V-SHARP) background field removal method using a region adaptive kernel (R-SHARP), in which a scalable spherical Gaussian kernel (SGK) is employed with its kernel radius and weights adjustable according to an energy "functional" reflecting the magnitude of field variation. Such an energy functional is defined in terms of a contour and two fitting functions incorporating regularization terms, from which a curve evolution model in level set formation is derived for energy minimization. We utilize it to detect regions of with a large field gradient caused by strong susceptibility variation. In such regions, the SGK will have a small radius and high weight at the sphere center in a manner adaptive to the voxel energy of the field perturbation. Using the proposed method, the background field generated from external sources can be effectively removed to get a more accurate estimation of the local field and thus of the QSM dipole inversion to map local tissue susceptibility sources. Numerical simulation, phantom and in vivo human brain data demonstrate improved performance of R-SHARP compared to V-SHARP and RESHARP (regularization enabled SHARP) methods, even when the whole paranasal sinus regions are preserved in the brain mask. Shadow artifacts due to strong susceptibility variations in the derived QSM maps could also be largely eliminated using the R-SHARP method, leading to more accurate QSM reconstruction.

Accuracy and variability of texture-based radiomics features of lung lesions across CT imaging conditions

NASA Astrophysics Data System (ADS)

Zheng, Yuese; Solomon, Justin; Choudhury, Kingshuk; Marin, Daniele; Samei, Ehsan

2017-03-01

Texture analysis for lung lesions is sensitive to changing imaging conditions but these effects are not well understood, in part, due to a lack of ground-truth phantoms with realistic textures. The purpose of this study was to explore the accuracy and variability of texture features across imaging conditions by comparing imaged texture features to voxel-based 3D printed textured lesions for which the true values are known. The seven features of interest were based on the Grey Level Co-Occurrence Matrix (GLCM). The lesion phantoms were designed with three shapes (spherical, lobulated, and spiculated), two textures (homogenous and heterogeneous), and two sizes (diameter < 1.5 cm and 1.5 cm < diameter < 3 cm), resulting in 24 lesions (with a second replica of each). The lesions were inserted into an anthropomorphic thorax phantom (Multipurpose Chest Phantom N1, Kyoto Kagaku) and imaged using a commercial CT system (GE Revolution) at three CTDI levels (0.67, 1.42, and 5.80 mGy), three reconstruction algorithms (FBP, IR-2, IR-4), four reconstruction kernel types (standard, soft, edge), and two slice thicknesses (0.6 mm and 5 mm). Another repeat scan was performed. Texture features from these images were extracted and compared to the ground truth feature values by percent relative error. The variability across imaging conditions was calculated by standard deviation across a certain imaging condition for all heterogeneous lesions. The results indicated that the acquisition method has a significant influence on the accuracy and variability of extracted features and as such, feature quantities are highly susceptible to imaging parameter choices. The most influential parameters were slice thickness and reconstruction kernels. Thin slice thickness and edge reconstruction kernel overall produced more accurate and more repeatable results. Some features (e.g., Contrast) were more accurately quantified under conditions that render higher spatial frequencies (e.g., thinner slice thickness and sharp kernels), while others (e.g., Homogeneity) showed more accurate quantification under conditions that render smoother images (e.g., higher dose and smoother kernels). Care should be exercised is relating texture features between cases of varied acquisition protocols, with need to cross calibration dependent on the feature of interest.

Background field removal using a region adaptive kernel for quantitative susceptibility mapping of human brain.

PubMed

Fang, Jinsheng; Bao, Lijun; Li, Xu; van Zijl, Peter C M; Chen, Zhong

2017-08-01

Background field removal is an important MR phase preprocessing step for quantitative susceptibility mapping (QSM). It separates the local field induced by tissue magnetic susceptibility sources from the background field generated by sources outside a region of interest, e.g. brain, such as air-tissue interface. In the vicinity of air-tissue boundary, e.g. skull and paranasal sinuses, where large susceptibility variations exist, present background field removal methods are usually insufficient and these regions often need to be excluded by brain mask erosion at the expense of losing information of local field and thus susceptibility measures in these regions. In this paper, we propose an extension to the variable-kernel sophisticated harmonic artifact reduction for phase data (V-SHARP) background field removal method using a region adaptive kernel (R-SHARP), in which a scalable spherical Gaussian kernel (SGK) is employed with its kernel radius and weights adjustable according to an energy "functional" reflecting the magnitude of field variation. Such an energy functional is defined in terms of a contour and two fitting functions incorporating regularization terms, from which a curve evolution model in level set formation is derived for energy minimization. We utilize it to detect regions of with a large field gradient caused by strong susceptibility variation. In such regions, the SGK will have a small radius and high weight at the sphere center in a manner adaptive to the voxel energy of the field perturbation. Using the proposed method, the background field generated from external sources can be effectively removed to get a more accurate estimation of the local field and thus of the QSM dipole inversion to map local tissue susceptibility sources. Numerical simulation, phantom and in vivo human brain data demonstrate improved performance of R-SHARP compared to V-SHARP and RESHARP (regularization enabled SHARP) methods, even when the whole paranasal sinus regions are preserved in the brain mask. Shadow artifacts due to strong susceptibility variations in the derived QSM maps could also be largely eliminated using the R-SHARP method, leading to more accurate QSM reconstruction. Copyright © 2017. Published by Elsevier Inc.

Whispering gallery modes in photoluminescence and Raman spectra of a spherical microcavity with CdTe quantum dots: anti-Stokes emission and interference effects

PubMed Central

Gaponik, Nikolai; Gerlach, Matthias; Donegan, John F; Savateeva, Diana; Rogach, Andrey L

2006-01-01

We have studied the photoluminescence and Raman spectra of a system consisting of a polystyrene latex microsphere coated by CdTe colloidal quantum dots. The cavity-induced enhancement of the Raman scattering allows the observation of Raman spectra from only a monolayer of CdTe quantum dots. Periodic structure with very narrow peaks in the photoluminescence spectra of a single microsphere was detected both in the Stokes and anti-Stokes spectral regions, arising from the coupling between the emission of quantum dots and spherical cavity modes.

Magnetorheological elastomer vibration isolation of tunable three-dimensional locally resonant acoustic metamaterial

NASA Astrophysics Data System (ADS)

Xu, Zhenlong; Tong, Jie; Wu, Fugen

2018-03-01

Magnetorheological elastomers (MREs) are used as cladding in three-dimensional locally resonant acoustic metamaterial (LRAM) cores. The metamaterial units are combined into a vibration isolator. Two types of LRAMs, namely, cubic and spherical kernels, are constructed. The finite element method is used to analyze the elastic band structures, transmittances, and vibration modes of the incident elastic waves. Results show that the central position and width of the LRAM elastic bandgap can be controlled by the application of an external magnetic field; furthermore, they can be adjusted by changing the MRE cladding thickness. These methods contribute to the design of metamaterial MRE vibration isolators.

Functionally charged nanosize particles differentially activate BV2 microglia.

EPA Science Inventory

The effect of particle surface charge on the biological activation of immortalized mouse microglia (BV2) was examined. Nanosize (860-950 nm) spherical polystyrene microparticles (SPM) were coated with carboxyl (COOH-) or dimethyl amino (CH3)2-N- groups to give a net negative or p...

Oral controlled release optimization of pellets prepared by extrusion-spheronization processing.

PubMed

Bianchini, R; Vecchio, C

1989-06-01

Controlled release high dosage forms of a typical drug such as Indobufen were prepared as multiple-unit doses by employing extrusion-spheronization processing and subsequently film coating operations. The effects of drug particle size, drug/binder ratio, extruder screen size and preparation reproducibility on the physical properties of the spherical granules were evaluated. Controlled release optimization was obtained on the same granules by coating with polymeric membranes of different thickness consisting of water-soluble and insoluble substances. Film coating was applied from an organic solution using pan coating technique. The drug diffusion is allowed by dissolution of part of the membrane leaving small channels of the polymer coat. Further preparations were conducted to evaluate coatings applied from aqueous dispersion (pseudolatex) using air suspension coating technique. In this system the drug diffusion is governed by the intrinsic pore network of the membrane. The most promising preparations having the desired in vitro release, were metered into hard capsules to obtain the drug unit dosage. Accelerated stability tests were carried out to assess the influence of time and the other storage parameters on the drug release profile.

Process for manufacture of inertial confinement fusion targets and resulting product

DOEpatents

Masnari, Nino A.; Rensel, Walter B.; Robinson, Merrill G.; Solomon, David E.; Wise, Kensall D.; Wuttke, Gilbert H.

1982-01-01

An ICF target comprising a spherical pellet of fusion fuel surrounded by a concentric shell; and a process for manufacturing the same which includes the steps of forming hemispheric shells of a silicon or other substrate material, adhering the shell segments to each other with a fuel pellet contained concentrically therein, then separating the individual targets from the parent substrate. Formation of hemispheric cavities by deposition or coating of a mold substrate is also described. Coatings or membranes may also be applied to the interior of the hemispheric segments prior to joining.

A preliminary report on a novel electrospray technique for nanoparticle based biomedical implants coating: precision electrospraying.

PubMed

Kumbar, Sangamesh G; Bhattacharyya, Subhabrata; Sethuraman, Swaminathan; Laurencin, Cato T

2007-04-01

The compatibility and biological efficacy of biomedical implants can be enhanced by coating their surface with appropriate agents. For predictable functioning of implants in situ, it is often desirable to obtain an extremely uniform coating thickness without effects on component dimensions or functions. Conventional coating techniques require rigorous processing conditions and often have limited adhesion and composition properties. In the present study, the authors report a novel precision electrospraying technique that allows both degradable and nondegradable coatings to be placed. Thin metallic slabs, springs, and biodegradable sintered microsphere scaffolds were coated with poly(lactide-co-glycolide) (PLAGA) using this technique. The effects of process parameters such as coating material concentration and applied voltage were studied using PLAGA and poly(ethylene glycol) coatings. Morphologies of coated surfaces were qualitatively characterized by scanning electron microscopy. Qualitative observations suggested that the coatings were composed of particles of various size/shape and agglomerates with different porous architectures. PLAGA coatings of uniform thickness were observed on all surfaces. Spherical nanoparticle poly(ethylene glycol) coatings (462-930 nm) were observed at all concentrations studied. This study found that the precision electrospraying technique is elegant, rapid, and reproducible with precise control over coating thickness (mum to mm) and is a useful alternative method for surface modification of biomedical implants. (c) 2006 Wiley Periodicals, Inc.

Optical Analysis of an Ultra-High resolution Two-Mirror Soft X-Ray Microscope

NASA Technical Reports Server (NTRS)

Shealy, David L.; Wang, Cheng; Hoover, Richard B.

1994-01-01

This work has summarized for a Schwarzschild microscope some relationships between numerical aperture (NA), magnification, diameter of the primary mirror, radius of curvature of the secondary mirror, and the total length of the microscope. To achieve resolutions better than a spherical Schwarzschild microscope of 3.3 Lambda for a perfectly aligned and fabricated system. it is necessary to use aspherical surfaces to control higher-order aberrations. For an NA of 0.35, the aspherical Head microscope provides diffraction limited resolution of 1.4 Lambda where the aspherical surfaces differ from the best fit spherical surface by approximately 1 micrometer. However, the angle of incidence varies significantly over the primary and the secondary mirrors, which will require graded multilayer coatings to operate near peak reflectivities. For higher numerical apertures, the variation of the angle of incidence over the secondary mirror surface becomes a serious problem which must be solved before multilayer coatings can be used for this application. Tolerance analysis of the spherical Schwarzschild microscope has shown that water window operations will require 2-3 times tighter tolerances to achieve a similar performance for operations with 130 A radiation. Surface contour errors have been shown to have a significant impact on the MTF and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror.

Effects of Forged Stock and Pure Aluminum Coating on Cryogenic Performance of Heat Treated Aluminum Mirrors

NASA Technical Reports Server (NTRS)

Toland, Ronald W.; Ohl, Raymond G.; Barthelmy, Michael P.; Zewari, S. Wahid; Greenhouse, Matthew A.; MacKenty, John W.

2003-01-01

We present the results of an on-going test program designed to empirically determine the effects of different stress relief procedures for aluminum mirrors. Earlier test results identified a preferred heat treatment for flat and spherical mirrors diamond turned from blanks cut out of Al 6061-T651 plate stock. Further tests have been performed on mirrors from forged stock and one set from plate stock coated with Alumiplate(trademark) aluminum coating to measure the effect of these variables on cryogenic performance. The mirrors are tested for figure error and radius of curvature at room temperature and at 80 K for three thermal cycles. We correlate the results of our optical testing with heat treatment and metallographic data.

Fast support vector data descriptions for novelty detection.

PubMed

Liu, Yi-Hung; Liu, Yan-Chen; Chen, Yen-Jen

2010-08-01

Support vector data description (SVDD) has become a very attractive kernel method due to its good results in many novelty detection problems. However, the decision function of SVDD is expressed in terms of the kernel expansion, which results in a run-time complexity linear in the number of support vectors. For applications where fast real-time response is needed, how to speed up the decision function is crucial. This paper aims at dealing with the issue of reducing the testing time complexity of SVDD. A method called fast SVDD (F-SVDD) is proposed. Unlike the traditional methods which all try to compress a kernel expansion into one with fewer terms, the proposed F-SVDD directly finds the preimage of a feature vector, and then uses a simple relationship between this feature vector and the SVDD sphere center to re-express the center with a single vector. The decision function of F-SVDD contains only one kernel term, and thus the decision boundary of F-SVDD is only spherical in the original space. Hence, the run-time complexity of the F-SVDD decision function is no longer linear in the support vectors, but is a constant, no matter how large the training set size is. In this paper, we also propose a novel direct preimage-finding method, which is noniterative and involves no free parameters. The unique preimage can be obtained in real time by the proposed direct method without taking trial-and-error. For demonstration, several real-world data sets and a large-scale data set, the extended MIT face data set, are used in experiments. In addition, a practical industry example regarding liquid crystal display micro-defect inspection is also used to compare the applicability of SVDD and our proposed F-SVDD when faced with mass data input. The results are very encouraging.

Biodegradable polymer based encapsulation of neem oil nanoemulsion for controlled release of Aza-A.

PubMed

Jerobin, Jayakumar; Sureshkumar, R S; Anjali, C H; Mukherjee, Amitava; Chandrasekaran, Natarajan

2012-11-06

Azadirachtin a biological compound found in neem have medicinal and pesticidal properties. The present work reports on the encapsulation of neem oil nanoemulsion using sodium alginate (Na-Alg) by cross linking with glutaraldehyde. Starch and polyethylene glycol (PEG) were used as coating agents for smooth surface of beads. The SEM images showed beads exhibited nearly spherical shape. Swelling of the polymeric beads reduced with coating which in turn decreased the rate of release of Aza-A. Starch coated encapsulation of neem oil nanoemulsion was found to be effective when compared to PEG coated encapsulation of neem oil nanoemulsion. The release rate of neem Aza-A from the beads into an aqueous environment was analyzed by UV-visible spectrophotometer (214 nm). The encapsulated neem oil nanoemulsion have the potential for controlled release of Aza-A. Neem oil nanoemulsion encapsulated beads coated with PEG was found to be toxic in lymphocyte cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Impregnation of glass fibres with polymethylmethacrylate using a powder-coating method

NASA Astrophysics Data System (ADS)

Vallittu, Pekka K.

1995-01-01

The aim of this study was to evaluate the usefulness of a powder-coating method to impregnate glass fibres with polymethylmethacrylate (PMMA) for dental purposes. The continuous unidirectional E-glass fibres, the surface of which had been treated with precured silane, were powder-coated with spherical PMMA particles. Before the powder-coated prepregs were used, the incorporated PMMA powder was dissolved with methylmethacrylate monomer. The degree of impregnation of the polymerized composite was determined with a scanning electron microscope. The results revealed that the mean degree of impregnation varied from 0.87 to 0.92, being lower in the heat-cured PMMA group (which simulated fabrication of a new denture), and higher in the autopolymerizing group (which simulated the repair of a fractured denture). The means between the two groups did not, however, differ significantly ( p=0.249). The results suggest that, even though the method has some shortcomings in terms of dental laboratory technology, the powder-coating method can be used to fabricate or repair acrylic resin-based dentures.

A flexible, extendable, modular and computationally efficient approach to scattering-integral-based seismic full waveform inversion

NASA Astrophysics Data System (ADS)

Schumacher, F.; Friederich, W.; Lamara, S.

2016-02-01

We present a new conceptual approach to scattering-integral-based seismic full waveform inversion (FWI) that allows a flexible, extendable, modular and both computationally and storage-efficient numerical implementation. To achieve maximum modularity and extendability, interactions between the three fundamental steps carried out sequentially in each iteration of the inversion procedure, namely, solving the forward problem, computing waveform sensitivity kernels and deriving a model update, are kept at an absolute minimum and are implemented by dedicated interfaces. To realize storage efficiency and maximum flexibility, the spatial discretization of the inverted earth model is allowed to be completely independent of the spatial discretization employed by the forward solver. For computational efficiency reasons, the inversion is done in the frequency domain. The benefits of our approach are as follows: (1) Each of the three stages of an iteration is realized by a stand-alone software program. In this way, we avoid the monolithic, unflexible and hard-to-modify codes that have often been written for solving inverse problems. (2) The solution of the forward problem, required for kernel computation, can be obtained by any wave propagation modelling code giving users maximum flexibility in choosing the forward modelling method. Both time-domain and frequency-domain approaches can be used. (3) Forward solvers typically demand spatial discretizations that are significantly denser than actually desired for the inverted model. Exploiting this fact by pre-integrating the kernels allows a dramatic reduction of disk space and makes kernel storage feasible. No assumptions are made on the spatial discretization scheme employed by the forward solver. (4) In addition, working in the frequency domain effectively reduces the amount of data, the number of kernels to be computed and the number of equations to be solved. (5) Updating the model by solving a large equation system can be done using different mathematical approaches. Since kernels are stored on disk, it can be repeated many times for different regularization parameters without need to solve the forward problem, making the approach accessible to Occam's method. Changes of choice of misfit functional, weighting of data and selection of data subsets are still possible at this stage. We have coded our approach to FWI into a program package called ASKI (Analysis of Sensitivity and Kernel Inversion) which can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. It is written in modern FORTRAN language using object-oriented concepts that reflect the modular structure of the inversion procedure. We validate our FWI method by a small-scale synthetic study and present first results of its application to high-quality seismological data acquired in the southern Aegean.

On the equivalence of spherical splines with least-squares collocation and Stokes's formula for regional geoid computation

NASA Astrophysics Data System (ADS)

Ophaug, Vegard; Gerlach, Christian

2017-11-01

This work is an investigation of three methods for regional geoid computation: Stokes's formula, least-squares collocation (LSC), and spherical radial base functions (RBFs) using the spline kernel (SK). It is a first attempt to compare the three methods theoretically and numerically in a unified framework. While Stokes integration and LSC may be regarded as classic methods for regional geoid computation, RBFs may still be regarded as a modern approach. All methods are theoretically equal when applied globally, and we therefore expect them to give comparable results in regional applications. However, it has been shown by de Min (Bull Géod 69:223-232, 1995. doi: 10.1007/BF00806734) that the equivalence of Stokes's formula and LSC does not hold in regional applications without modifying the cross-covariance function. In order to make all methods comparable in regional applications, the corresponding modification has been introduced also in the SK. Ultimately, we present numerical examples comparing Stokes's formula, LSC, and SKs in a closed-loop environment using synthetic noise-free data, to verify their equivalence. All agree on the millimeter level.

Analysis of the nonlinearity of Asian summer monsoon intraseasonal variability using spherical PDFs

NASA Astrophysics Data System (ADS)

Jajcay, Nikola; Hannachi, Abdel

2013-04-01

The Asian summer monsoon (ASM) is a high-dimensional and highly complex phenomenon affecting more than one fifth of the world population. The intraseasonal component of the ASM undergoes periods of active and break phases associated respectively with enhanced and reduced rainfall over the Indian subcontinent and surroundings. In this paper the nonlinear nature of the intraseasonal monsoon variability is investigated using the leading EOFs of ERA-40 sea level pressure reanalyses field over the ASM region. The probability density function is then computed in spherical coordinates using a Epaneshnikov kernel method. Three significant modes are identified. They represent respectively (i) East - West mode with above normal sea level pressure over East China sea and below normal pressure over Himalayas, (ii) mode with above normal sea level pressure over East China sea (without compensating centre of opposite sign as in (i)) and (iii) mode with below normal sea level pressure over East China sea (same as (ii) but with opposite sign). Relationship to large scale flow are also investigated and discussed.

Design and characterization of calcium alginate microparticles coated with polycations as protein delivery system.

PubMed

Zarate, J; Virdis, L; Orive, G; Igartua, M; Hernández, R M; Pedraz, J L

2011-01-01

Bovine serum albumin (BSA) loaded calcium alginate microparticles (MPs) produced in this study by a w/o emulsification and external gelation method exhibited spherical and fairly smooth and porous morphology with 1.052 ± 0.057 µm modal particle size. The high permeability of the calcium alginate hydrogel lead to a potent burst effect and too fast protein release. To overcome these problems, MPs were coated with polycations, such as chitosan, poly-L-lysine and DEAE-dextran. Our results demonstrated that coated MPs showed slower release and were able to significantly reduce the release of BSA in the first hour. Therefore, this method can be applied to prepare coated alginate MPs which could be an optimal system for the controlled release of biotherapeutic molecules. Nevertheless, further studies are needed to optimize delivery properties which could provide a sustained release of proteins.

Measurement of Interfacial Adhesion in Glass-Epoxy Systems Using the Indentation Method

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

Hutchins, Karen Isabel

2015-07-01

The adhesion of coatings often controls the performance of the substrate-coating system. Certain engineering applications require an epoxy coating on a brittle substrate to protect and improve the performance of the substrate. Experimental observations and measurements of interfacial adhesion in glass-epoxy systems are described in this thesis. The Oliver and Pharr method was utilized to calculate the bulk epoxy hardness and elastic modulus. Spherical indentations were used to induce delaminations at the substrate-coating interface. The delamination sizes as a function of load were used to calculate the interfacial toughness. The interfacial fracture energy of my samples is an order ofmore » magnitude higher than a previous group who studied a similar glass-epoxy system. A comparison study of how different glass treatments affect adhesion was also conducted: smooth versus rough, clean versus dirty, stressed versus non-stressed.« less

Preparation and characterization of hydroxyapatite-coated iron oxide particles by spray-drying technique.

PubMed

Donadel, Karina; Felisberto, Marcos D V; Laranjeira, Mauro C M

2009-06-01

Magnetic particles of iron oxide have been increasingly used in medical diagnosis by magnetic resonance imaging and in cancer therapies involving targeted drug delivery and magnetic hyperthermia. In this study we report the preparation and characterization of iron oxide particles coated with bioceramic hydroxyapatite by spray-drying. The iron oxide magnetic particles (IOMP) were coated with hydroxyapatite (HAp) by spray-drying using two IOMP/HAp ratios (0.7 and 3.2). The magnetic particles were characterized by way of scanning electronic microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transformed infrared spectroscopy, flame atomic absorption spectrometry,vibrating sample magnetometry and particle size distribution (laser diffraction). The surface morphology of the coated samples is different from that of the iron oxide due to formation of hydroxyapatite coating. From an EDX analysis, it was verified that the surface of the coated magnetic particles is composed only of HAp, while the interior containsiron oxide and a few layers of HAp as expected. The results showed that spray-drying technique is an efficient and relatively inexpensive method for forming spherical particles with a core/shell structure.

Cavity enhanced atomic magnetometry

PubMed Central

Crepaz, Herbert; Ley, Li Yuan; Dumke, Rainer

2015-01-01

Atom sensing based on Faraday rotation is an indispensable method for precision measurements, universally suitable for both hot and cold atomic systems. Here we demonstrate an all-optical magnetometer where the optical cell for Faraday rotation spectroscopy is augmented with a low finesse cavity. Unlike in previous experiments, where specifically designed multipass cells had been employed, our scheme allows to use conventional, spherical vapour cells. Spherical shaped cells have the advantage that they can be effectively coated inside with a spin relaxation suppressing layer providing long spin coherence times without addition of a buffer gas. Cavity enhancement shows in an increase in optical polarization rotation and sensitivity compared to single-pass configurations. PMID:26481853

On removing interpolation and resampling artifacts in rigid image registration.

PubMed

Aganj, Iman; Yeo, Boon Thye Thomas; Sabuncu, Mert R; Fischl, Bruce

2013-02-01

We show that image registration using conventional interpolation and summation approximations of continuous integrals can generally fail because of resampling artifacts. These artifacts negatively affect the accuracy of registration by producing local optima, altering the gradient, shifting the global optimum, and making rigid registration asymmetric. In this paper, after an extensive literature review, we demonstrate the causes of the artifacts by comparing inclusion and avoidance of resampling analytically. We show the sum-of-squared-differences cost function formulated as an integral to be more accurate compared with its traditional sum form in a simple case of image registration. We then discuss aliasing that occurs in rotation, which is due to the fact that an image represented in the Cartesian grid is sampled with different rates in different directions, and propose the use of oscillatory isotropic interpolation kernels, which allow better recovery of true global optima by overcoming this type of aliasing. Through our experiments on brain, fingerprint, and white noise images, we illustrate the superior performance of the integral registration cost function in both the Cartesian and spherical coordinates, and also validate the introduced radial interpolation kernel by demonstrating the improvement in registration.

On Removing Interpolation and Resampling Artifacts in Rigid Image Registration

PubMed Central

Aganj, Iman; Yeo, Boon Thye Thomas; Sabuncu, Mert R.; Fischl, Bruce

2013-01-01

We show that image registration using conventional interpolation and summation approximations of continuous integrals can generally fail because of resampling artifacts. These artifacts negatively affect the accuracy of registration by producing local optima, altering the gradient, shifting the global optimum, and making rigid registration asymmetric. In this paper, after an extensive literature review, we demonstrate the causes of the artifacts by comparing inclusion and avoidance of resampling analytically. We show the sum-of-squared-differences cost function formulated as an integral to be more accurate compared with its traditional sum form in a simple case of image registration. We then discuss aliasing that occurs in rotation, which is due to the fact that an image represented in the Cartesian grid is sampled with different rates in different directions, and propose the use of oscillatory isotropic interpolation kernels, which allow better recovery of true global optima by overcoming this type of aliasing. Through our experiments on brain, fingerprint, and white noise images, we illustrate the superior performance of the integral registration cost function in both the Cartesian and spherical coordinates, and also validate the introduced radial interpolation kernel by demonstrating the improvement in registration. PMID:23076044

Segmentation of 3D microPET images of the rat brain via the hybrid gaussian mixture method with kernel density estimation.

PubMed

Chen, Tai-Been; Chen, Jyh-Cheng; Lu, Henry Horng-Shing

2012-01-01

Segmentation of positron emission tomography (PET) is typically achieved using the K-Means method or other approaches. In preclinical and clinical applications, the K-Means method needs a prior estimation of parameters such as the number of clusters and appropriate initialized values. This work segments microPET images using a hybrid method combining the Gaussian mixture model (GMM) with kernel density estimation. Segmentation is crucial to registration of disordered 2-deoxy-2-fluoro-D-glucose (FDG) accumulation locations with functional diagnosis and to estimate standardized uptake values (SUVs) of region of interests (ROIs) in PET images. Therefore, simulation studies are conducted to apply spherical targets to evaluate segmentation accuracy based on Tanimoto's definition of similarity. The proposed method generates a higher degree of similarity than the K-Means method. The PET images of a rat brain are used to compare the segmented shape and area of the cerebral cortex by the K-Means method and the proposed method by volume rendering. The proposed method provides clearer and more detailed activity structures of an FDG accumulation location in the cerebral cortex than those by the K-Means method.

Retrieval of the aerosol size distribution in the complex anomalous diffraction approximation

NASA Astrophysics Data System (ADS)

Franssens, Ghislain R.

This contribution reports some recently achieved results in aerosol size distribution retrieval in the complex anomalous diffraction approximation (ADA) to MIE scattering theory. This approximation is valid for spherical particles that are large compared to the wavelength and have a refractive index close to 1. The ADA kernel is compared with the exact MIE kernel. Despite being a simple approximation, the ADA seems to have some practical value for the retrieval of the larger modes of tropospheric and lower stratospheric aerosols. The ADA has the advantage over MIE theory that an analytic inversion of the associated Fredholm integral equation becomes possible. In addition, spectral inversion in the ADA can be formulated as a well-posed problem. In this way, a new inverse formula was obtained, which allows the direct computation of the size distribution as an integral over the spectral extinction function. This formula is valid for particles that both scatter and absorb light and it also takes the spectral dispersion of the refractive index into account. Some details of the numerical implementation of the inverse formula are illustrated using a modified gamma test distribution. Special attention is given to the integration of spectrally truncated discrete extinction data with errors.

Genetic diversity of rice tungro spherical virus in tungro-endemic provinces of the Philippines and Indonesia.

PubMed

Azzam, O; Yambao, M L; Muhsin, M; McNally, K L; Umadhay, K M

2000-01-01

The two adjacent genes of coat protein 1 and 2 of rice tungro spherical virus (RTSV) were amplified from total RNA extracts of serologically indistinguishable field isolates from the Philippines and Indonesia, using reverse transcriptase polymerase chain reaction (RT-PCR). Digestion with HindIII and BstYI restriction endonucleases differentiated the amplified DNA products into eight distinct coat protein genotypes. These genotypes were then used as indicators of virus diversity in the field. Inter- and intra-site diversities were determined over three cropping seasons. At each of the sites surveyed, one or two main genotypes prevailed together with other related minor or mixed genotypes that did not replace the main genotype over the sampling time. The cluster of genotypes found at the Philippines sites was significantly different from the one at the Indonesia sites, suggesting geographic isolation for virus populations. Phylogenetic studies based on the nucleotide sequences of 38 selected isolates confirm the spatial distribution of RTSV virus populations but show that gene flow may occur between populations. Under the present conditions, rice varieties do not seem to exert selective pressure on the virus populations. Based on the selective constraints in the coat protein amino acid sequences and the virus genetic composition per site, a negative selection model followed by random-sampling events due to vector transmissions is proposed to explain the inter-site diversity observed.

Observation and Kinematic Description of Long Actin Tracks Induced by Spherical Beads

PubMed Central

Kang, Hyeran; Perlmutter, David S.; Shenoy, Vivek B.; Tang, Jay X.

2010-01-01

We report an in vitro study comparing the growth of long actin tails induced by spherical beads coated with the verprolin central acidic domain of the polymerization enzyme N-WASP to that induced by Listeria monocytogenes in similar cellular extracts. The tracks behind the beads show characteristic differences in shape and curvature from those left by the bacteria, which have an elongated shape and a similar polymerization-inducing enzyme distributed only on the rear surface of the cell. The experimental tracks are simulated using a generalized kinematic model, which incorporates three modes of bead rotation with respect to the tail. The results show that the trajectories of spherical beads are mechanically deterministic rather than random, as suggested by stochastic models. Assessment of the bead rotation and its mechanistic basis offers insights into the biological function of actin-based motility. PMID:21044576

Electromagnetic retroreflection augmented by spherical and conical metasurfaces

NASA Astrophysics Data System (ADS)

Shang, Yuping; Shen, Zhongxiang

2017-11-01

The focus of this paper is on phase gradient metasurfaces conformal to spherical and conical bodies of revolution, with an aim of engineering retroreflections and therefore augmenting backscattering cross-sections of those three-dimensional geometries under the illumination of a plane electromagnetic wave. Based on the conducting sphere and cone, the effect of the geometric revolution property on the selection of the unit inclusion of metasurfaces is considered. The procedure for using the selected unit inclusion to implement the proper reflection phase gradient onto the illuminated surfaces of those objects is formulated in detail. Retroreflections resembling conducting plates under normal incidence are observed for both the conducting sphere and cone coated with conformal metasurfaces. As a result, the redirection-induced retroreflection effectively contributes to the backscattering cross-section enhancement. A good agreement between full-wave simulations and measurements demonstrates the validity and effectiveness of backscattering cross-section enhancement using spherical and conical metasurfaces.

Dual-phase-shift spherical Fizeau interferometer for reduction of noise due to internally scattered light

NASA Astrophysics Data System (ADS)

Kumagai, Toshiki; Hibino, Kenichi; Nagaike, Yasunari

2017-03-01

Internally scattered light in a Fizeau interferometer is generated from dust, defects, imperfect coating of the optical components, and multiple reflections inside the collimator lens. It produces additional noise fringes in the observed interference image and degrades the repeatability of the phase measurement. A method to reduce the phase measurement error is proposed, in which the test surface is mechanically translated between each phase measurement in addition to an ordinary phase shift of the reference surface. It is shown that a linear combination of several measured phases at different test surface positions can reduce the phase errors caused by the scattered light. The combination can also compensate for the nonuniformity of the phase shift that occurs in spherical tests. A symmetric sampling of the phase measurements can cancel the additional primary spherical aberrations that occur when the test surface is out of the null position of the confocal configuration.

Experimental Evaluation and Optimization of Flank Wear During Turning of AISI 4340 Steel with Coated Carbide Inserts Using Different Cutting Fluids

NASA Astrophysics Data System (ADS)

Lawal, S. A.; Choudhury, I. A.; Nukman, Y.

2015-01-01

The understanding of cutting fluids performance in turning process is very important in order to improve the efficiency of the process. This efficiency can be determined based on certain process parameters such as flank wear, cutting forces developed, temperature developed at the tool chip interface, surface roughness on the work piece, etc. In this study, the objective is to determine the influence of cutting fluids on flank wear during turning of AISI 4340 with coated carbide inserts. The performances of three types of cutting fluids were compared using Taguchi experimental method. The results show that palm kernel oil based cutting fluids performed better than the other two cutting fluids in reducing flank wear. Mathematical models for cutting parameters such as cutting speed, feed rate, depth of cut and cutting fluids were obtained from regression analysis using MINITAB 14 software to predict flank wear. Experiments were conducted based on the optimized values to validate the regression equations for flank wear and 5.82 % error was obtained. The optimal cutting parameters for the flank wear using S/N ratio were 160 m/min of cutting speed (level 1), 0.18 mm/rev of feed (level 1), 1.75 mm of depth of cut (level 2) and 2.97 mm2/s palm kernel oil based cutting fluid (level 3). ANOVA shows cutting speed of 85.36 %; and feed rate 4.81 %) as significant factors.

Enhanced performance of spherical natural graphite coated by Li4Ti5O12 as anode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Lu, Mi; Tian, Yanyan; Zheng, Xiaodong; Gao, Jun; Huang, Bing

2012-12-01

The natural graphite (NG) is coated with Li4Ti5O12 (LTO) and the composite shows a markedly enhanced rate performance due to the decrease of charge transfer resistance after LTO coating. The specific capacity of the NG charge-discharged at 2 C is increased by 60.3% (128.7 vs. 80.3 mAh g-1) by coating it with 1 wt.% of Li4Ti5O12 (LTO). The comparison of the NG and that coated with 1 wt.% LTO at 0.1 C shows that the initial reversible capacity is increased from 318.1 mAh g-1 to 357.5 mAh g-1 after coating, while the total irreversible capacity loss after 50 cycles is decreased from 122.8 mAh g-1 to 103.9 mAh g-1. The composite improves the energy and power densities, safety, cycle life and lowers the price of the lithium-ion battery while avoiding the gas-swelling of full battery caused by Ti4+ because the final coating material is the lithiated LTO (Li7Ti5O12 or Li9Ti5O12).

A collision probability analysis of the double-heterogeneity problem

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

Hebert, A.

1993-10-01

A practical collision probability model is presented for the description of geometries with many levels of heterogeneity. Regular regions of the macrogeometry are assumed to contain a stochastic mixture of spherical grains or cylindrical tubes. Simple expressions for the collision probabilities in the global geometry are obtained as a function of the collision probabilities in the macro- and microgeometries. This model was successfully implemented in the collision probability kernel of the APOLLO-1, APOLLO-2, and DRAGON lattice codes for the description of a broad range of reactor physics problems. Resonance self-shielding and depletion calculations in the microgeometries are possible because eachmore » microregion is explicitly represented.« less

Method for preparing spherical ferrite beads and use thereof

DOEpatents

Lauf, Robert J.; Anderson, Kimberly K.; Montgomery, Frederick C.; Collins, Jack L.

2002-01-01

The invention allows the fabrication of small, dense, highly polished spherical beads of hexagonal ferrites with selected compositions for use in nonreciprocal microwave and mm-wave devices as well as in microwave absorbent or reflective coatings, composites, and the like. A porous, generally spherical bead of hydrous iron oxide is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead is washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) under conditions of elevated temperature and pressure to convert the bead into a mixed hydrous iron-alkaline earth oxide while retaining the generally spherical shape. This mixed oxide bead is then washed, dried, and calcined to produce the desired (BaFe.sub.12 O.sub.19 or SrFe.sub.12 O.sub.19) crystal structure. The calcined bead is then sintered to form a dense bead of the BaFe.sub.12 O.sub.19 and SrFe.sub.12 O.sub.19 phase suitable for polishing and incorporation into various microwave devices and components.

Carbon monoxide formation in UO 2 kerneled HTR fuel particles containing oxygen getters

NASA Astrophysics Data System (ADS)

Proksch, E.; Strigl, A.; Nabielek, H.

1986-06-01

Mass spectrometric measurements of CO in irradiated UO 2 kerneled HTR fuel particles containing various oxygen getters are summarized and evaluated. Uranium carbide addition in the 3 to 15% range reduces the CO release by factors between 25 and 80, up to burn-up levels as high as 70% FIMA. Unintentional gettering by SiC in TRISO coated particles with failed inner pyrocarbon layers results in CO reduction factors between 15 and 110. For ZrC, only somewhat ambiguous results have been obtained; most likely, ZrC results in CO reduction by a factor of about 40. Ce 2O 3 and La 2O 3 seem to be somewhat less effective than the three carbides; for Ce 2O 3, reduction factors between 3 and 15 have been found. However, these results are possibly incorrect due to premature oxidation of the getter already during fabrication. Addition of SiO 2 + Al 2O 3 has no influence on CO release at all.

Curvature dependence of the effect of ionic functionalization on the attraction among nanoparticles in dispersion

NASA Astrophysics Data System (ADS)

Jabes, B. Shadrack; Bratko, Dusan; Luzar, Alenka

2018-06-01

Solubilization of nanoparticles facilitates nanomaterial processing and enables new applications. An effective method to improve dispersibility in water is provided by ionic functionalization. We explore how the necessary extent of functionalization depends on the particle geometry. Using molecular dynamics/umbrella sampling simulations, we determine the effect of the solute curvature on solvent-averaged interactions among ionizing graphitic nanoparticles in aqueous dispersion. We tune the hydrophilicity of molecular-brush coated fullerenes, carbon nanotubes, and graphane platelets by gradually replacing a fraction of the methyl end groups of the alkyl coating by the ionizing -COOK or -NH3Cl groups. To assess the change in nanoparticles' dispersibility in water, we determine the potential-of-mean-force profiles at varied degrees of ionization. When the coating comprises only propyl groups, the attraction between the hydrophobic particles intensifies from spherical to cylindrical to planar geometry. This is explained by the increasing fraction of surface groups that can be brought into contact and the reduced access to water molecules, both following the above sequence. When ionic groups are added, however, the dispersibility increases in the opposite order, with the biggest effect in the planar geometry and the smallest in the spherical geometry. These results highlight the important role of geometry in nanoparticle solubilization by ionic functionalities, with about twice higher threshold surface charge necessary to stabilize a dispersion of spherical than planar particles. At 25%-50% ionization, the potential of mean force reaches a plateau because of the counterion condensation and saturated brush hydration. Moreover, the increase in the fraction of ionic groups can weaken the repulsion through counterion correlations between adjacent nanoparticles. High degrees of ionization and concomitant ionic screening gradually reduce the differences among surface interactions in distinct geometries until an essentially curvature-independent dispersion environment is created. Insights into tuning nanoparticle interactions can guide the synthesis of a broad class of nonpolar nanoparticles, where solubility is achieved by ionic functionalization.

Influence of Powder Morphology and Microstructure on the Cold Spray and Mechanical Properties of Ti6Al4V Coatings

NASA Astrophysics Data System (ADS)

Munagala, Venkata Naga Vamsi; Akinyi, Valary; Vo, Phuong; Chromik, Richard R.

2018-06-01

The powder microstructure and morphology has significant influence on the cold sprayability of Ti6Al4V coatings. Here, we compare the cold sprayability and properties of coatings obtained from Ti6Al4V powders of spherical morphology (SM) manufactured using plasma gas atomization and irregular morphology (IM) manufactured using the Armstrong process. Coatings deposited using IM powders had negligible porosity and better properties compared to coatings deposited using SM powders due to higher particle impact velocities, porous surface morphology and more deformable microstructure. To evaluate the cohesive strength, multi-scale indentation was performed and hardness loss parameter was calculated. Coatings deposited using SM powders exhibited poor cohesive strength compared to coatings deposited using IM powders. Images of the residual indents showed de-bonding and sliding of adjacent splats in the coatings deposited using SM powders irrespective of the load. Coatings deposited using IM powders showed no evidence of de-bonding at low loads. At high loads, splat de-bonding was observed resulting in hardness loss despite negligible porosity. Thus, while the powders from Armstrong process lead to a significant improvement in sprayability and coating properties, further optimization of powder and cold spray process will be required as well as consideration of post-annealing treatments to obtain acceptable cohesive strength.

Thyme and basil essential oils included in edible coatings as a natural preserving method of oilseed kernels.

PubMed

Riveros, Cecilia G; Nepote, Valeria; Grosso, Nelson R

2016-01-15

Sunflower seeds are susceptible to developing rancidity and off-flavours through lipid oxidation. Edible coatings and essential oils have proven antioxidant properties in different food products. The purpose of this study was to evaluate the combined effect of using an edible coating and thyme and basil essential oils to preserve the chemical and sensory quality parameters of roasted sunflower seeds during storage. 50% DPPH inhibitory concentration (IC50) values of 0.278 and 0.0997 µg mL(-1) were observed for thyme and basil, respectively. On storage day 40, peroxide values were 80.68, 70.28, 68.43, 49.31 and 33.87 mEq O2 kg(-1) in roasted sunflower seeds (RS), roasted sunflower seeds coated with carboxymethyl cellulose (CMC) (RS-CMC), roasted sunflower seeds coated with CMC added with basil (RS-CMC-A), thyme (RS-CMC-T) and butylated hydroxytoluene (RS-CMC-BHT), respectively. RS-CMC-T and RS-CMC-BHT presented the lowest peroxide values, conjugated dienes and p-anisidine values during storage. RS-CMC-BHT, RS-CMC-T, and RS-CMC-A showed the lowest oxidized and cardboard flavour intensity ratings. On storage day 40, roasted sunflower flavour intensity ratings were higher in RS-CMC-T and RS-CMC-A. Thyme and basil essential oils added to the CMC coating improved the sensory stability of this product during storage, but only thyme essential oil increased their chemical stability. © 2015 Society of Chemical Industry.

Molecular spectroscopy from 5-12 μm using an OP-GaP OPO

NASA Astrophysics Data System (ADS)

Maidment, Luke; Schunemann, Peter G.; Reid, Derryck T.

2017-02-01

We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation patterned gallium phosphide (OP-GaP) and being the first example of a broadband OPO operating across the molecular fingerprint region. OP-GaP crystals with lengths of 1 mm and several patterning periods were diced, polished, and antireflection (AR) coated for near- to mid-infrared wavelengths. We configured a synchronously pumped OP-GaP OPO in a 101.2-MHz resonator with high reflectivity from 1.15-1.35 μm, pumped with 150-fs pulses from a 1040-nm femtosecond laser (Chromacity Spark). The coating of one spherical mirror was optimized for transmission at the pump wavelength of 1040 nm and for high reflectivity at the resonant signal wavelength in a range from 1.15-1.35 μm, while the other spherical mirror collimated the idler beam emerging from the OP-GaP crystal and was silver coated to provide high reflectivity for all idler wavelengths. This collimated idler beam was output-coupled from the cavity by transmission through a plane mirror coated with high transmission for the idler wavelengths (5-12 μm) and high reflectivity for the signal wavelengths (1.15-1.35 μm) on an infrared-transparent ZnSe substrate. Idler spectra centered from 5.4-11.8 μm and extending to 12.5 μm were collected. The maximum average power was 55 mW at 5.4 μm with 7.5 mW being recorded at 11.8 μm. Details of Fourier transform spectroscopy using water vapor and a polystyrene reference standard are presented.

Live celloidosome structures based on the assembly of individual cells by colloid interactions.

PubMed

Fakhrullin, Rawil F; Brandy, Marie-Laure; Cayre, Olivier J; Velev, Orlin D; Paunov, Vesselin N

2010-10-14

A new class of colloid structures, celloidosomes, has been developed which represent hollow microcapsules whose membranes consist of a single monolayer of living cells. Two routes for producing these structures were designed based on templating of: (i) air bubbles and (ii) anisotropic microcrystals of calcium carbonate with living cells, which allowed us to fabricate celloidosomes of spherical, rhombohedral and needle-like morphologies. Air microbubbles were templated by yeast cells coated with poly(allylamine hydrochloride) (PAH), then coated with carboxymethylcellulose and rehydrated resulting in the formation of spherical multicellular structures. Similarly, calcium carbonate microcrystals of anisotropic shapes were coated with several consecutive layers of oppositely charged polyelectrolytes to obtain a positive surface charge which was used to immobilise yeast cells coated with anionic polyelectrolyte of their surfaces. After dissolving of sacrificial cores, hollow multicellular structures were obtained. The viability of the cells in the produced structures was confirmed by using fluorescein diacetate. In order to optimize the separation of celloidosomes from free cells magnetic nanoparticles were immobilised onto the surface of templates prior to the cells deposition, which greatly facilitated the separation using a permanent magnet. Two alternative approaches were developed to form celloidosome structures using magnetically functionalised core-shell microparticles which resulted in the formation of celloidosomes with needle-like and cubic-like geometries which follows the original morphology of the calcium carbonate microcrystals. Our methods for fabrication of celloidosomes may found applications in the development of novel symbiotic bio-structures, artificial multicellular organisms and in tissue engineering. The unusual structure of celloidosomes resembles the primitive forms of multicellular species, like Volvox, and other algae and could be regarded as one possible mechanism of the evolutionary development of multicellularity.

Measurements of impurity concentrations and transport in the Lithium Tokamak Experiment

NASA Astrophysics Data System (ADS)

Boyle, Dennis Patrick

This thesis presents new measurements of core impurity concentrations and transport in plasmas with lithium coatings on all-metal plasma facing components (PFCs) in the Lithium Tokamak Experiment (LTX). LTX is a modest-sized spherical tokamak uniquely capable of operating with large area solid and/or liquid lithium coatings essentially surrounding the entire plasma (as opposed to just the divertor or limiter region in other devices). Lithium (Li) wall-coatings have improved plasma performance and confinement in several tokamaks with carbon (C) PFCs, including the National Spherical Torus Experiment (NSTX). In NSTX, contamination of the core plasma with Li impurities was very low (<0.1%) despite extensive divertor coatings. Low Li levels in NSTX were found to be largely due to neoclassical forces from the high level of C impurities. Studying impurity levels and transport with Li coatings on stainless steel surfaces in LTX is relevant to future devices (including future enhancements to NSTX-Upgrade) with all-metal PFCs. The new measurements in this thesis were enabled by a refurbished Thomson scattering system and improved impurity spectroscopy, primarily using a novel visible spectrometer monitoring several Li, C, and oxygen (O) emission lines. A simple model was used to account for impurities in unmeasured charge states, assuming constant density in the plasma core and constant concentration in the edge. In discharges with solid Li coatings, volume averaged impurity concentrations were low but non-negligible, with 2-4% Li, 0.6-2% C, 0.4-0.7% O, and Z eff<1.2. Transport was assessed using the TRANSP, NCLASS, and MIST codes. Collisions with the main H ions dominated the neoclassical impurity transport, unlike in NSTX, where collisions with C dominated. Furthermore, neoclassical transport coefficients calculated with NCLASS were similar across all impurity species and differed no more than a factor of two, in contrast to NSTX where they differed by an order of magnitude. However, time-independent simulations with MIST indicated that unlike NSTX, neoclassical theory did not fully capture the impurity transport and anomalous transport likely played a significant role in determining impurity profiles.

Measurements of impurity concentrations and transport in the Lithium Tokamak Experiment

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

Boyle, Dennis Patrick

This thesis presents new measurements of core impurity concentrations and transport in plasmas with lithium coatings on all-metal plasma facing components (PFCs) in the Lithium Tokamak Experiment (LTX). LTX is a modest-sized spherical tokamak uniquely capable of operating with large area solid and/or liquid lithium coatings essentially surrounding the entire plasma (as opposed to just the divertor or limiter region in other devices). Lithium (Li) wall-coatings have improved plasma performance and confinement in several tokamaks with carbon (C) PFCs, including the National Spherical Torus Experiment (NSTX). In NSTX, contamination of the core plasma with Li impurities was very low (<0.1%)more » despite extensive divertor coatings. Low Li levels in NSTX were found to be largely due to neoclassical forces from the high level of C impurities. Studying impurity levels and transport with Li coatings on stainless steel surfaces in LTX is relevant to future devices (including future enhancements to NSTX-Upgrade) with all-metal PFCs. The new measurements in this thesis were enabled by a refurbished Thomson scattering system and improved impurity spectroscopy, primarily using a novel visible spectrometer monitoring several Li, C, and oxygen (O) emission lines. A simple model was used to account for impurities in unmeasured charge states, assuming constant density in the plasma core and constant concentration in the edge. In discharges with solid Li coatings, volume averaged impurity concentrations were low but non-negligible, with~2-4% Li, ~0.6-2% C, ~0.4-0.7% O, and Z_eff<1.2. Transport was assessed using the TRANSP, NCLASS, and MIST codes. Collisions with the main H ions dominated the neoclassical impurity transport, unlike in NSTX, where collisions with C dominated. Furthermore, neoclassical transport coefficients calculated with NCLASS were similar across all impurity species and differed no more than a factor of two, in contrast to NSTX where they differed by an order of magnitude. However, time-independent simulations with MIST indicated that unlike NSTX, neoclassical theory did not fully capture the impurity transport and anomalous transport likely played a significant role in determining impurity profiles.« less

Mechanics of biomimetic systems propelled by actin comet tails

NASA Astrophysics Data System (ADS)

Kang, Hyeran; Tambe, Dhananjay; Shenoy, Vivek; Tang, Jay

2009-03-01

The motility of intracellular bacterial pathogens such as Listeria monocytogenes is driven by filamentous actin comet tails in a variety of trajectories. Here, we present the in vitro study on the actin-based movements using spherical beads of different sizes coated with VCA protein, a partial domain of N-Wasp, in platelet extracts. Long term two-dimensional trajectories of the spherical beads motility show characteristic difference than those observed for bacteria, which have both elongated shape and asymmetric expression of the polymerization inducing enzyme. The trajectories also vary sensitively with the bead size and shape. These results provide a useful test to our new analytical model including the rotation of the bead relative to the tail.

Microstructural effect on radiative scattering coefficient and asymmetry factor of anisotropic thermal barrier coatings

NASA Astrophysics Data System (ADS)

Chen, X. W.; Zhao, C. Y.; Wang, B. X.

2018-05-01

Thermal barrier coatings are common porous materials coated on the surface of devices operating under high temperatures and designed for heat insulation. This study presents a comprehensive investigation on the microstructural effect on radiative scattering coefficient and asymmetry factor of anisotropic thermal barrier coatings. Based on the quartet structure generation set algorithm, the finite-difference-time-domain method is applied to calculate angular scattering intensity distribution of complicated random microstructure, which takes wave nature into account. Combining Monte Carlo method with Particle Swarm Optimization, asymmetry factor, scattering coefficient and absorption coefficient are retrieved simultaneously. The retrieved radiative properties are identified with the angular scattering intensity distribution under different pore shapes, which takes dependent scattering and anisotropic pore shape into account implicitly. It has been found that microstructure significantly affects the radiative properties in thermal barrier coatings. Compared with spherical shape, irregular anisotropic pore shape reduces the forward scattering peak. The method used in this paper can also be applied to other porous media, which designs a frame work for further quantitative study on porous media.

Synthetic Spores Give Insight into the Real Thing and Reveal Functional Applications | Center for Cancer Research

Cancer.gov

Spores from bacteria, such as Bacillus subtilis, are produced to allow the bacterium’s genetic material to survive harsh environments. When the bacterium senses nutrient depletion, it divides asymmetrically into a forespore and a mother cell. The mother cell engulfs the forespore, and coat proteins synthesized by the mother cell localize to the surface of the forespore. The mother cell eventually ruptures, releasing the mature spore, which is surrounded by a thick shell of approximately 70 different proteins. This protein coat is one of the most durable static biological structures, but, because of its complexity, detailed studies of how the coat forms have been lacking. Kumaran Ramamurthi, Ph.D., of CCR’s Laboratory of Molecular Biology, and his colleagues including postdoctoral fellow and lead author of the study I-Lin Wu, Ph.D., decided to investigate the assembly of the basement layer of the spore coat by decorating spherical membranes supported by silica beads with SpoIVA and SpoVM, proteins which are known to be required for coat assembly.

In Vitro Sustained Release Study of Gallic Acid Coated with Magnetite-PEG and Magnetite-PVA for Drug Delivery System

PubMed Central

Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Bin Hussein, Mohd Zobir; Fakurazi, Sharida; Shaari, Abdul Halim; Ahmad, Zalinah

2014-01-01

The efficacy of two nanocarriers polyethylene glycol and polyvinyl alcohol magnetic nanoparticles coated with gallic acid (GA) was accomplished via X-ray diffraction, infrared spectroscopy, magnetic measurements, thermal analysis, and TEM. X-ray diffraction and TEM results showed that Fe3O4 nanoparticles were pure iron oxide having spherical shape with the average diameter of 9 nm, compared with 31 nm and 35 nm after coating with polyethylene glycol-GA (FPEGG) and polyvinyl alcohol-GA (FPVAG), respectively. Thermogravimetric analyses proved that after coating the thermal stability was markedly enhanced. Magnetic measurements and Fourier transform infrared (FTIR) revealed that superparamagnetic iron oxide nanoparticles could be successfully coated with two polymers (PEG and PVA) and gallic acid as an active drug. Release behavior of gallic acid from two nanocomposites showed that FPEGG and FPVAG nanocomposites were found to be sustained and governed by pseudo-second-order kinetics. Anticancer activity of the two nanocomposites shows that the FPEGG demonstrated higher anticancer effect on the breast cancer cell lines in almost all concentrations tested compared to FPVAG. PMID:24737969

Structural coloration of chitosan coated cellulose fabrics by electrostatic self-assembled poly (styrene-methyl methacrylate-acrylic acid) photonic crystals.

PubMed

Yavuz, Gönül; Zille, Andrea; Seventekin, Necdet; Souto, Antonio P

2018-08-01

The structural coloration of a chitosan-coated woven cotton fabric obtained by glutaraldehyde-stabilized deposition of electrostatic self-assembled monodisperse and spherically uniform (250 nm) poly (styrene-methyl methacrylate-acrylic acid) photonic crystal nanospheres (P(St-MMA-AA)) was investigated. Bright iridescent coatings displaying different colors in function of the viewing angle were obtained. The SEM, diffuse reflectance spectroscopy, TGA, DSC and FTIR analyses confirm the presence of structural color and the glutaraldehyde and chitosan ability to provide durable chemical bonding between cotton fabric and photonic crystal (PCs) coating with the highest degradation temperature and the lowest enthalpy. The coatings are characterized by a mixture of face-centered cubic and hexagonal close-packed arrays alternating random packing regions. For the first time a cost-efficient structural coloration with high washing and light fastness using self-assembled P(St-MMA-AA) photonic crystals was successfully developed onto woven cotton fabric using chitosan and/or glutaraldehyde as stabilizing agent opening new strategies for the development of dye-free coloration of textiles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Absorption and scattering by fractal aggregates and by their equivalent coated spheres

NASA Astrophysics Data System (ADS)

Kandilian, Razmig; Heng, Ri-Liang; Pilon, Laurent

2015-01-01

This paper demonstrates that the absorption and scattering cross-sections and the asymmetry factor of randomly oriented fractal aggregates of spherical monomers can be rapidly estimated as those of coated spheres with equivalent volume and average projected area. This was established for fractal aggregates with fractal dimension ranging from 2.0 to 3.0 and composed of up to 1000 monodisperse or polydisperse monomers with a wide range of size parameter and relative complex index of refraction. This equivalent coated sphere approximation was able to capture the effects of both multiple scattering and shading among constituent monomers on the integral radiation characteristics of the aggregates. It was shown to be superior to the Rayleigh-Debye-Gans approximation and to the equivalent coated sphere approximation proposed by Latimer. However, the scattering matrix element ratios of equivalent coated spheres featured large angular oscillations caused by internal reflection in the coating which were not observed in those of the corresponding fractal aggregates. Finally, the scattering phase function and the scattering matrix elements of aggregates with large monomer size parameter were found to have unique features that could be used in remote sensing applications.

Effect of Particle Morphology on Cold Spray Deposition of Chromium Carbide-Nickel Chromium Cermet Powders

NASA Astrophysics Data System (ADS)

Fernandez, Ruben; Jodoin, Bertrand

2017-08-01

Nickel chromium-chromium carbide coatings provide good corrosion and wear resistance at high temperatures, making them ideal for applications where a harsh environment and high temperatures are expected. Thermal spray processes are preferred as deposition technique of cermets, but the high process temperatures can lead to decarburization and reduction of the coatings properties. Cold spray uses lower temperatures preventing decarburization. Since the metallic phase remains solid, the feedstock powder morphology becomes crucial on the deposition behavior. Six commercially available powders were studied, varying in morphology and metal/ceramic ratios. The powders were categorized into 4 groups depending on their morphology. Spherical powders lead to substrate erosion due to their limited overall ductility. Porous agglomerated and sintered powders lead to severely cracked coatings. For dense agglomerated and sintered powders, the outcome depended on the initial metal/ceramic ratio: powders with 25 wt.% NiCr led to substrate erosion while 35 wt.% NiCr powders led to dense coatings. Finally, blended ceramic-metal mixtures also lead to dense coatings. All coatings obtained had lower ceramic content than the initial feedstock powders. Interrupted spray tests, combined with FEA, helped drawing conclusions on the deposition behavior to explain the obtained results.

Atomic layer deposition of titanium oxide films on As-synthesized magnetic Ni particles: Magnetic and safety properties

NASA Astrophysics Data System (ADS)

Uudeküll, Peep; Kozlova, Jekaterina; Mändar, Hugo; Link, Joosep; Sihtmäe, Mariliis; Käosaar, Sandra; Blinova, Irina; Kasemets, Kaja; Kahru, Anne; Stern, Raivo; Tätte, Tanel; Kukli, Kaupo; Tamm, Aile

2017-05-01

Spherical nickel particles with size in the range of 100-400 nm were synthesized by non-aqueous liquid phase benzyl alcohol method. Being developed for magnetically guided biomedical applications, the particles were coated by conformal and antimicrobial thin titanium oxide films by atomic layer deposition. The particles retained their size and crystal structure after the deposition of oxide films. The sensitivity of the coated particles to external magnetic fields was increased compared to that of the uncoated powder. Preliminary toxicological investigations on microbial cells and small aquatic crustaceans revealed non-toxic nature of the synthesized particles.

High-temperature characteristics of advanced Ni-MH batteries using nickel electrodes containing CaF 2

NASA Astrophysics Data System (ADS)

Zhang, Xuezeng; Gong, Zhixin; Zhao, Shumei; Geng, Mingming; Wang, Yan; Northwood, Derek O.

The high-temperature charge acceptance of Ni-MH batteries has been improved through the addition of calcium fluoride to the pasted nickel hydroxide electrode made using spherical Co(OH) 2-coated nickel hydroxide powder. The charge acceptance of the Ni-MH battery at 60 °C is over 95% at 1 C charge/discharge rates. The charge acceptance at 60 °C remains at over 90% through 10 cycles. The use of Co(OH) 2-coated Ni(OH) 2 plus a CaF 2 addition to the positive electrode also significantly improved the high-temperature stability in terms of reduced gas evolution.

Modularized seismic full waveform inversion based on waveform sensitivity kernels - The software package ASKI

NASA Astrophysics Data System (ADS)

Schumacher, Florian; Friederich, Wolfgang; Lamara, Samir; Gutt, Phillip; Paffrath, Marcel

2015-04-01

We present a seismic full waveform inversion concept for applications ranging from seismological to enineering contexts, based on sensitivity kernels for full waveforms. The kernels are derived from Born scattering theory as the Fréchet derivatives of linearized frequency-domain full waveform data functionals, quantifying the influence of elastic earth model parameters and density on the data values. For a specific source-receiver combination, the kernel is computed from the displacement and strain field spectrum originating from the source evaluated throughout the inversion domain, as well as the Green function spectrum and its strains originating from the receiver. By storing the wavefield spectra of specific sources/receivers, they can be re-used for kernel computation for different specific source-receiver combinations, optimizing the total number of required forward simulations. In the iterative inversion procedure, the solution of the forward problem, the computation of sensitivity kernels and the derivation of a model update is held completely separate. In particular, the model description for the forward problem and the description of the inverted model update are kept independent. Hence, the resolution of the inverted model as well as the complexity of solving the forward problem can be iteratively increased (with increasing frequency content of the inverted data subset). This may regularize the overall inverse problem and optimizes the computational effort of both, solving the forward problem and computing the model update. The required interconnection of arbitrary unstructured volume and point grids is realized by generalized high-order integration rules and 3D-unstructured interpolation methods. The model update is inferred solving a minimization problem in a least-squares sense, resulting in Gauss-Newton convergence of the overall inversion process. The inversion method was implemented in the modularized software package ASKI (Analysis of Sensitivity and Kernel Inversion), which provides a generalized interface to arbitrary external forward modelling codes. So far, the 3D spectral-element code SPECFEM3D (Tromp, Komatitsch and Liu, 2008) and the 1D semi-analytical code GEMINI (Friederich and Dalkolmo, 1995) in both, Cartesian and spherical framework are supported. The creation of interfaces to further forward codes is planned in the near future. ASKI is freely available under the terms of the GPL at www.rub.de/aski . Since the independent modules of ASKI must communicate via file output/input, large storage capacities need to be accessible conveniently. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full waveform inversion. In the presentation, we will show some aspects of the theory behind the full waveform inversion method and its practical realization by the software package ASKI, as well as synthetic and real-data applications from different scales and geometries.

The interplay of nanointerface curvature and calcium binding in weak polyelectrolyte-coated nanoparticles.

PubMed

Nap, Rikkert J; Gonzalez Solveyra, Estefania; Szleifer, Igal

2018-05-01

When engineering nanomaterials for application in biological systems, it is important to understand how multivalent ions, such as calcium, affect the structural and chemical properties of polymer-modified nanoconstructs. In this work, a recently developed molecular theory was employed to study the effect of surface curvature on the calcium-induced collapse of end-tethered weak polyelectrolytes. In particular, we focused on cylindrical and spherical nanoparticles coated with poly(acrylic acid) in the presence of different amounts of Ca2+ ions. We describe the structural changes that grafted polyelectrolytes undergo as a function of calcium concentration, surface curvature, and morphology. The polymer layers collapse in aqueous solutions that contain sufficient amounts of Ca2+ ions. This collapse, due to the formation of calcium bridges, is not only controlled by the calcium ion concentration but also strongly influenced by the curvature of the tethering surface. The transition from a swollen to a collapsed layer as a function of calcium concentration broadens and shifts to lower amounts of calcium ions as a function of the radius of cylindrical and spherical nanoparticles. The results show how the interplay between calcium binding and surface curvature governs the structural and functional properties of the polymer molecules. This would directly impact the fate of weak polyelectrolyte-coated nanoparticles in biological environments, in which calcium levels are tightly regulated. Understanding such interplay would also contribute to the rational design and optimization of smart interfaces with applications in, e.g., salt-sensitive and ion-responsive materials and devices.

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

Yoncheva, K., E-mail: krassi.yoncheva@gmail.com; Popova, M.; Szegedi, A.

Non-functionalized and amino-functionalized mesoporous silica nanoparticle were loaded with anti-inflammatory drug budesonide and additionally post-coated with bioadhesive polymer (carbopol). TEM images showed spherical shape of the nanoparticles and slightly higher polydispersity after coating with carbopol. Nitrogen physisorption and thermogravimetic analysis revealed that more efficient loading and incorporation into the pores of nanoparticles was achieved with the amino-functionalized silica carrier. Infrared spectra indicated that the post-coating of these nanoparticles with carbopol led to the formation of bond between amino groups of the functionalized carrier and carboxyl groups of carbopol. The combination of amino-functionalization of the carrier with the post-coating of themore » nanoparticles sustained budesonide release. Further, an in vitro model of inflammatory bowel disease showed that the cytoprotective effect of budesonide loaded in the post-coated silica nanoparticles on damaged HT-29 cells was more pronounced compared to the cytoprotection obtained with pure budesonide. -- Graphical abstract: Silica mesoporous MCM-41 particles were amino-functionalized, loaded with budesonide and post-coated with bioadhesive polymer (carbopol) in order to achieve prolonged residence of anti-inflammatory drug in GIT. Highlights: • Higher drug loading in amino-functionalized mesoporous silica. • Amino-functionalization and post-coating of the nanoparticles sustained drug release. • Achievement of higher cytoprotective effect with drug loaded into the nanoparticles.« less

Microstructure of Desmanthus illinoensis

NASA Astrophysics Data System (ADS)

Wood, Delilah F.; Orts, William J.; Glenn, Gregory M.

2010-06-01

Structure and histochemistry of mature seeds of Desmanthus illinoensis (Illinois bundle flower) show that the seed has typical legume structure. The seed can be separated into two major fractions including the seed coat/endosperm and the embryo. The seed coat consists of a cuticle, palisade sclereids, hour glass cells and mesophyll. Endosperm is attached to the inner portion of the seed coat and is thicker beneath the pleurogram in the center of the seed. The embryo consists mostly of two large cotyledons, the major storage structures of the seed. The cotyledons are high in protein which occurs in protein bodies. Protein bodies in the cotyledons include those without inclusions, those with phytin inclusions and those with calcium-rich crystals. The phytin inclusions are spherical and have high phosphorus and magnesium contents. The calcium-rich crystals are also included inside protein bodies and are druse-type crystals.

Multidimensional Multiphysics Simulation of TRISO Particle Fuel

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

J. D. Hales; R. L. Williamson; S. R. Novascone

2013-11-01

Multidimensional multiphysics analysis of TRISO-coated particle fuel using the BISON finite-element based nuclear fuels code is described. The governing equations and material models applicable to particle fuel and implemented in BISON are outlined. Code verification based on a recent IAEA benchmarking exercise is described, and excellant comparisons are reported. Multiple TRISO-coated particles of increasing geometric complexity are considered. It is shown that the code's ability to perform large-scale parallel computations permits application to complex 3D phenomena while very efficient solutions for either 1D spherically symmetric or 2D axisymmetric geometries are straightforward. Additionally, the flexibility to easily include new physical andmore » material models and uncomplicated ability to couple to lower length scale simulations makes BISON a powerful tool for simulation of coated-particle fuel. Future code development activities and potential applications are identified.« less

Cryochemical and CVD processing of shperical carbide fuels for propulsion reactors

NASA Astrophysics Data System (ADS)

Blair, H. Thomas; Carroll, David W.; Matthews, R. Bruce

1991-01-01

Many of the nuclear propulsion reactor concepts proposed for a manned mission to Mars use a coated spherical particle fuel form similar to that used in the Rover and NERVA propulsion reactors. The formation of uranium dicarbide microspheres using a cryochemical process and the coating of the UC2 spheres with zirconium carbide using chemical vapor deposition are being developed at Los Alamos National Laboratory. The cryochemical process is described with a discussion of the variables affecting the sphere formation and carbothermic reduction to produce UC2 spheres from UO2. Emphasis is placed on minimizing the wastes produced by the process. The ability to coat particles with ZrC was recaptured, and improvements in the process and equipment were developed. Volatile organometallic precursors were investigated as alternatives to the original ZrCl4 precursor.

Uniformity Masks Design Method Based on the Shadow Matrix for Coating Materials with Different Condensation Characteristics

PubMed Central

2013-01-01

An intuitionistic method is proposed to design shadow masks to achieve thickness profile control for evaporation coating processes. The proposed method is based on the concept of the shadow matrix, which is a matrix that contains coefficients that build quantitive relations between shape parameters of masks and shadow quantities of substrate directly. By using the shadow matrix, shape parameters of shadow masks could be derived simply by solving a matrix equation. Verification experiments were performed on a special case where coating materials have different condensation characteristics. By using the designed mask pair with complementary shapes, thickness uniformities of better than 98% are demonstrated for MgF2 (m = 1) and LaF3 (m = 0.5) simultaneously on a 280 mm diameter spherical substrate with the radius curvature of 200 mm. PMID:24227996

Electrochemical studies on LiCoO 2 surface coated with Y 3Al 5O 12 for lithium-ion cells

NASA Astrophysics Data System (ADS)

Chen, Jin-Ming; Cho, Yung-Da; Hsiao, Chiao-Ling; Fey, George Ting-Kuo

Synthesized yttrium aluminum garnet (YAG) sol was coated on the surface of the LiCoO 2 cathode particles by an in situ sol-gel process, followed by calcination at 923 K for 10 h in air. Based on XRD, TEM, and ESCA data, a compact YAG kernel with an average thickness of ∼20 nm was formed on the surface of the core LiCoO 2 particles, which ranged from ∼90 to 120 nm in size. The charge-discharge cycling studies for the coated materials suggest that 0.3 wt.% YAG-coated LiCoO 2 heated at 923 K for 10 h in air, delivered a discharge capacity of 167 mAh g -1 and a cycle stability of about 164 cycles with a fading rate of 0.2 mAh cycle -1 at a 0.2 C-rate between 2.75 and 4.40 V vs. Li/Li +. The differential capacity plots revealed that impedance growth was slower for YAG surface treated LiCoO 2, when cells were charged at 4.40 V. DSC results exemplified that the exothermic peak at ∼468 K corresponded to the release of much less oxygen and greater thermal-stability.

Suspended-Bed Reactor preliminary design, /sup 233/U--/sup 232/Th cycle. Final report (revised)

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

Karam, R.A.; Alapour, A.; Lee, C.C.

1977-11-01

The preliminary design Suspended-Bed Reactor is described. Coated particles about 2 mm in diameter are used as the fuel. The coatings consist of three layers: (1) low density pyrolytic graphite, 70 ..mu.. thick, (2) silicon carbide pressure vessel, 30 ..mu.. thick, and (3) ZrC layer, 50 ..mu.. thick, to protect the pressure vessel from moisture and oxygen. The fuel kernel can be either uranium-thorium dicarbide or metal. The coated particles are suspended by helium gas (coolant) in a cluster of pressurized tubes. The upward flow of helium fluidizes the coated particles. As the flow rate increases, the bed of particlesmore » is lifted upward to the core section. The particles are restrained at the upper end of the core by a suitable screen. The overall particle density in the core is just enough for criticality condition. Should the helium flow cease, the bed in the core section will collapse, and the particles will flow downward into the section where the increased physical spacings among the tubes brings about a safe shutdown. By immersing this section of the tubes in a large graphite block to serve as a heat sink, dissipation of decay heat becomes manageable. This eliminates the need for emergency core cooling systems.« less

Seismic waveform sensitivity to global boundary topography

NASA Astrophysics Data System (ADS)

Colombi, Andrea; Nissen-Meyer, Tarje; Boschi, Lapo; Giardini, Domenico

2012-09-01

We investigate the implications of lateral variations in the topography of global seismic discontinuities, in the framework of high-resolution forward modelling and seismic imaging. We run 3-D wave-propagation simulations accurate at periods of 10 s and longer, with Earth models including core-mantle boundary topography anomalies of ˜1000 km spatial wavelength and up to 10 km height. We obtain very different waveform signatures for PcP (reflected) and Pdiff (diffracted) phases, supporting the theoretical expectation that the latter are sensitive primarily to large-scale structure, whereas the former only to small scale, where large and small are relative to the frequency. PcP at 10 s seems to be well suited to map such a small-scale perturbation, whereas Pdiff at the same frequency carries faint signatures that do not allow any tomographic reconstruction. Only at higher frequency, the signature becomes stronger. We present a new algorithm to compute sensitivity kernels relating seismic traveltimes (measured by cross-correlation of observed and theoretical seismograms) to the topography of seismic discontinuities at any depth in the Earth using full 3-D wave propagation. Calculation of accurate finite-frequency sensitivity kernels is notoriously expensive, but we reduce computational costs drastically by limiting ourselves to spherically symmetric reference models, and exploiting the axial symmetry of the resulting propagating wavefield that collapses to a 2-D numerical domain. We compute and analyse a suite of kernels for upper and lower mantle discontinuities that can be used for finite-frequency waveform inversion. The PcP and Pdiff sensitivity footprints are in good agreement with the result obtained cross-correlating perturbed and unperturbed seismogram, validating our approach against full 3-D modelling to invert for such structures.

Efficiency calibration of the first multilayer-coated holographic ion-etched flight grating for a sounding rocket high-resolution spectrometer.

PubMed

Kowalski, M P; Barbee, T W; Heidemann, K F; Gursky, H; Rife, J C; Hunter, W R; Fritz, G G; Cruddace, R G

1999-11-01

We have fabricated the four flight gratings for a sounding rocket high-resolution spectrometer using a holographic ion-etching technique. The gratings are spherical (4000-mm radius of curvature), large (160 mm x 90 mm), and have a laminar groove profile of high density (3600 grooves/mm). They have been coated with a high-reflectance multilayer of Mo/Si. Using an atomic force microscope, we examined the surface characteristics of the first grating before and after multilayer coating. The average roughness is approximately 3 A rms after coating. Using synchrotron radiation, we completed an efficiency calibration map over the wavelength range 225-245 A. At an angle of incidence of 5 degrees and a wavelength of 234 A, the average efficiency in the first inside order is 10.4 +/- 0.5%, and the derived groove efficiency is 34.8 +/- 1.6%. These values exceed all previously published results for a high-density grating.

Pedestal substrate for coated optics

DOEpatents

Hale, Layton C.; Malsbury, Terry N.; Patterson, Steven R.

2001-01-01

A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

Influence of carbonyl iron particle coating with silica on the properties of magnetorheological elastomers

NASA Astrophysics Data System (ADS)

Małecki, P.; Królewicz, M.; Hiptmair, F.; Krzak, J.; Kaleta, J.; Major, Z.; Pigłowski, J.

2016-10-01

In this paper, the influence of encapsulating carbonyl iron particles with various silica coatings on the properties of magnetorheological elastomers (MREs) was investigated. A soft styrene-ethylene-butylene-styrene thermoplastic elastomer was used as the composite’s polymer matrix. Spherical carbonyl iron powder (CIP) acted as the ferromagnetic filler. In order to improve the metal-polymer interaction, carbonyl iron particles were coated with two types of single and six types of double silica layers. The first layer was created through a TMOS or TEOS hydrolysis whereas the second one was composed of organosilanes. The mechanical properties of MREs containing 38.5 vol% of CIP were analysed under dynamic loading conditions. To investigate the magnetorheological effect in these composites, a 430 mT magnetic field, generated by an array of permanent magnets, was applied during testing. The results revealed that the magnetomechanical response of the MREs differs substantially, depending on the kind of particle coating.

Cracking the chocolate egg problem: polymeric films coated on curved substrates

NASA Astrophysics Data System (ADS)

Brun, Pierre-Thomas; Lee, Anna; Marthelot, Joel; Balestra, Gioele; Gallaire, François; Reis, Pedro

2015-11-01

Inspired by the traditional chocolate egg recipe, we show that pouring a polymeric solution onto spherical molds yields a simple and robust path of fabrication of thin elastic curved shells. The drainage dynamics naturally leads to uniform coatings frozen in time as the polymer cures, which are subsequently peeled off their mold. We show how the polymer curing affects the drainage dynamics and eventually selects the shell thickness and sets its uniformity. To this end, we perform coating experiments using silicon based elastomers, Vinylpolysiloxane (VPS) and Polydimethylsiloxane (PDMS). These results are rationalized combining numerical simulations of the lubrication flow field to a theoretical model of the dynamics yielding an analytical prediction of the formed shell characteristics. In particular, the robustness of the coating technique and its flexibility, two critical features for providing a generic framework for future studies, are shown to be an inherent consequence of the flow field (memory loss). The shell structure is both independent of initial conditions and tailorable by changing a single experimental parameter.

Effect of 3-D viscoelastic structure on post-seismic relaxation from the 2004 M = 9.2 Sumatra earthquake

USGS Publications Warehouse

Pollitz, F.; Banerjee, P.; Grijalva, K.; Nagarajan, B.; Burgmann, R.

2008-01-01

The 2004 M=9.2 Sumatra-Andaman earthquake profoundly altered the state of stress in a large volume surrounding the ???1400 km long rupture. Induced mantle flow fields and coupled surface deformation are sensitive to the 3-D rheology structure. To predict the post-seismic motions from this earthquake, relaxation of a 3-D spherical viscoelastic earth model is simulated using the theory of coupled normal modes. The quasi-static deformation basis set and solution on the 3-D model is constructed using: a spherically stratified viscoelastic earth model with a linear stress-strain relation; an aspherical perturbation in viscoelastic structure; a 'static'mode basis set consisting of Earth's spheroidal and toroidal free oscillations; a "viscoelastic" mode basis set; and interaction kernels that describe the coupling among viscoelastic and static modes. Application to the 2004 Sumatra-Andaman earthquake illustrates the profound modification of the post-seismic flow field at depth by a slab structure and similarly large effects on the near-field post-seismic deformation field at Earth's surface. Comparison with post-seismic GPS observations illustrates the extent to which viscoelastic relaxation contributes to the regional post-seismic deformation. ?? Journal compilation ?? 2008 RAS.

Core-shell structured SiO2@YVO4:Dy3+/Sm3+ phosphor particles: sol-gel preparation and characterization.

PubMed

Wang, H; Yu, M; Lin, C K; Lin, J

2006-08-01

Spherical SiO(2) particles have been coated with YVO(4):Dy(3+)/Sm(3+) phosphor layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO(2)@YVO(4):Dy(3+)/Sm(3+) particles. X-ray diffraction (XRD), Fourier-transform IR spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting SiO(2)@YVO(4):Dy(3+)/Sm(3+) core-shell phosphors. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 300 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (20 nm for one deposition cycle). The core-shell particles show strong characteristic emission from Dy(3+) for SiO(2)@YVO(4):Dy(3+) and from Sm(3+) for SiO(2)@YVO(4):Sm(3+) due to an efficient energy transfer from YVO(4) host to them. The PL intensity of Dy(3+) and Sm(3+) increases with raising the annealing temperature and the number of coating cycles.

Application of spherical silicate to prepare solid dispersion dosage forms with aqueous polymers.

PubMed

Nagane, Kentaro; Kimura, Susumu; Ukai, Koji; Takahashi, Chisato; Ogawa, Noriko; Yamamoto, Hiromitsu

2015-09-30

The objective of this study is to prepare and characterize solid dispersions of nifedipine (NP) using porous spherical silicate micro beads (MB) that were approximately 100 μm in diameter with vinylpyrrolidone/vinyl acetate copolymer (PVP/VA) and a Wurster-type fluidized bed granulator. Compared with previously reported solid dispersion using only MB, the supersaturation of NP dissolved from the proposed system of MB and PVP/VA was maintained during dissolution tests. The proposed system produced a solid dispersion product coated on MB, and morphology was maintained after the coating process to prepare solid dispersion; therefore, the powder characteristics, such as flowability of the proposed solid dispersion product, was tremendously preferable to that of the conventional spray-dried solid dispersions of NP with PVP/VA, expecting to make the consequent manufacturing processes easy for development. Another advantage in the terms of manufacturing is its simple process to prepare solid dispersion by spraying the drug and polymer that were dissolved in an organic solvent onto a MB in a Wurster-type fluidized bed granulator, thus, simplifying the optimization and scale-up with ease. Copyright © 2015 Elsevier B.V. All rights reserved.

A novel process for production of spherical PBT powders and their processing behavior during laser beam melting

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

Schmidt, Jochen, E-mail: jochen.schmidt@fau.de; Sachs, Marius; Fanselow, Stephanie

2016-03-09

Additive manufacturing processes like laser beam melting of polymers are established for production of prototypes and individualized parts. The transfer to other areas of application and to serial production is currently hindered by the limited availability of polymer powders with good processability. Within this contribution a novel process route for the production of spherical polymer micron-sized particles of good flowability has been established and applied to produce polybutylene terephthalate (PBT) powders. Moreover, the applicability of the PBT powders in selective laser beam melting and the dependencies of process parameters on device properties will be outlined. First, polymer micro particles aremore » produced by a novel wet grinding method. To improve the flowability the produced particles the particle shape is optimized by rounding in a heated downer reactor. A further improvement of flowability of the cohesive spherical PBT particles is realized by dry coating. An improvement of flowability by a factor of about 5 is achieved by subsequent rounding of the comminution product and dry-coating as proven by tensile strength measurements of the powders. The produced PBT powders were characterized with respect to their processability. Therefore thermal, rheological, optical and bulk properties were analyzed. Based on these investigations a range of processing parameters was derived. Parameter studies on thin layers, produced in a selective laser melting system, were conducted. Hence appropriate parameters for processing the PBT powders by laser beam melting, like building chamber temperature, scan speed and laser power have been identified.« less

Thermal conductivity of zirconia thermal barrier coatings

NASA Technical Reports Server (NTRS)

Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

1995-01-01

Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor description (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard power or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increase upon being exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicates that if these coatings reach a temperature above 1100 C during operation, they will begin to lose their effectiveness as a thermal barrier.

Thermal conductivity of zirconia thermal barrier coatings

NASA Technical Reports Server (NTRS)

Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

1995-01-01

Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor deposition (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard powder or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increases upon exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as-fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicate that if these coatings reach a temperature above 1100 C during operation, they will begin to lose their effectiveness as a thermal barrier.

Non-linear 3-D Born shear waveform tomography in Southeast Asia

NASA Astrophysics Data System (ADS)

Panning, Mark P.; Cao, Aimin; Kim, Ahyi; Romanowicz, Barbara A.

2012-07-01

Southeast (SE) Asia is a tectonically complex region surrounded by many active source regions, thus an ideal test bed for developments in seismic tomography. Much recent development in tomography has been based on 3-D sensitivity kernels based on the first-order Born approximation, but there are potential problems with this approach when applied to waveform data. In this study, we develop a radially anisotropic model of SE Asia using long-period multimode waveforms. We use a theoretical 'cascade' approach, starting with a large-scale Eurasian model developed using 2-D Non-linear Asymptotic Coupling Theory (NACT) sensitivity kernels, and then using a modified Born approximation (nBorn), shown to be more accurate at modelling waveforms, to invert a subset of the data for structure in a subregion (longitude 75°-150° and latitude 0°-45°). In this subregion, the model is parametrized at a spherical spline level 6 (˜200 km). The data set is also inverted using NACT and purely linear 3-D Born kernels. All three final models fit the data well, with just under 80 per cent variance reduction as calculated using the corresponding theory, but the nBorn model shows more detailed structure than the NACT model throughout and has much better resolution at depths greater than 250 km. Based on variance analysis, the purely linear Born kernels do not provide as good a fit to the data due to deviations from linearity for the waveform data set used in this modelling. The nBorn isotropic model shows a stronger fast velocity anomaly beneath the Tibetan Plateau in the depth range of 150-250 km, which disappears at greater depth, consistent with other studies. It also indicates moderate thinning of the high-velocity plate in the middle of Tibet, consistent with a model where Tibet is underplated by Indian lithosphere from the south and Eurasian lithosphere from the north, in contrast to a model with continuous underplating by Indian lithosphere across the entire plateau. The nBorn anisotropic model detects negative ξ anomalies suggestive of vertical deformation associated with subducted slabs and convergent zones at the Himalayan front and Tien Shan at depths near 150 km.

Corrosion Experiments Using Spherical Uranium Powders

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

Powell, G. L.; Siekhaus, W. J.; Teslich, N. E.

2017-02-01

Corrosion experiments using spherical U powders are continuing with scanning electron microscopy (SEM) showing that the particles are highly textured, 5 m to 25 m diameters with 4% larger particles that are fused smaller particles. This U has a high specific surface area with no corners or back-sides, is well annealed with no machining work, and coated with a coherent oxide film, 30 nm to 300 nm thick. Exposure of this powder to low vapor pressure H 2O in the absence of O 2, i.e., a vacuum desiccator, resulted in a coherent oxide film growth of ~1 m/y, ~ 10Xmore » the growth rate in ambient air, displaying fracture along the growth plane at ~300 nm.« less

Single-axis four-mirror system: large spherical primary and small fields

NASA Astrophysics Data System (ADS)

Baranne, Andre

1998-08-01

A catoptric corrector of modest size can be used for large spherical primaries, easily integrated at the prime focus, this corrector gives back to the system, aspect and properties of 2-mirrors classical telescopes. In the last few years, progress in active and adaptative optics makes possible a lot of things, progress in measuring distances, new ideas on optical coatings, new materials and so on in a near future, all that makes the instrumentalist dreamy It is said that nobody knows today if the size of 3rd millennium telescopes will be limited or not by a theoretical, physical or technical phenomenon, thus let us imagine but with thoughtfulness because our projects will be surely restricted by financial considerations

Tribological Properties of Ti(Al,O)/Al2O3 Composite Coating by Thermal Spraying

NASA Astrophysics Data System (ADS)

Salman, Asma; Gabbitas, Brian; Cao, Peng; Zhang, Deliang

The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity air fuel (HVAF) thermally sprayed wear resistant Ti(Al,O)/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting and dummy blocks aluminium extrusion. A feedstock of Ti(Al,O)/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity air-fuel (HVAF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The wear resistance of the coating was investigated by a tribometer using a spherical ended alumina pin as a counter body under dry and lubricating conditions. The results showed that composite coating has lower wear rate at high temperature than at room temperature without using lubricant. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

[Infrared spectroscopic study on the component and vigor analysis of Cistanche deserticola seeds].

PubMed

Xu, Rong; Sun, Su-Qin; Chen, Jun; Chen, Shi-Lin; Zhou, Feng

2009-01-01

Comparative study of the different parts of cistanche deserticola seeds and their changes after different processing were examined by Fourier transform infrared spectroscopy spectra (FTIR). The results of the analysis showed that components in the cistanche deserticola seeds were abundant, which contained characteristic absorption peaks of protein, fat and carbohydrate. As well, pectin and aromatic compound can be also found in the seeds. However, the components were different in different parts of cistanche deserticola seeds. The characteristic absorption peak intensities of fat at 2,926, 1,746, 1,161 and 721 cm(-1) were the strongest in the seed kernels. However, the seed coats mainly consisted of carbohydrate and pectin, which were showed at 1,054 cm(-1). The contents of protein and carbohydrate were decreased distinctly in the moldy and dead seeds after processing. The characteristic absorption peak intensity ratio of protein to fat (I1,630/I1,745 ) was all higher than 1.05 in the live seeds. The characteristic absorption peak intensity ratio of amido link I of protein to fat (11,653/I1,745) in the dead seed kernels of the cistanche deserticola was decreased from 0.31 to 0. 23, which was 25.8% less than that in vital seed kernels. The results suggest that FTIR not only can be used in fast comprehensive analysis of seed components, but also can be used in the seed vigor analysis, seed longevity determination and seed quality evaluation.

Analysis of an Interface Crack for a Functionally Graded Strip Sandwiched between Two Homogeneous Layers of Finite Thickness

NASA Technical Reports Server (NTRS)

Shbeeh, N. I.; Binienda, W. K.

1999-01-01

The interface crack problem for a composite layer that consists of a homogeneous substrate, coating and a non-homogeneous interface was formulated for singular integral equations with Cauchy kernels and integrated using the Lobatto-Chebyshev collocation technique. Mixed-mode Stress Intensity Factors and Strain Energy Release Rates were calculated. The Stress Intensity Factors were compared for accuracy with relevant results previously published. The parametric studies were conducted for the various thickness of each layer and for various non-homogeneity ratios. Particular application to the Zirconia thermal barrier on steel substrate is demonstrated.

Thermochromic microcapsules with highly transparent shells obtained through in-situ polymerization of urea formaldehyde around thermochromic cores for smart wood coatings.

PubMed

Zhu, Xiaodong; Liu, Yu; Li, Zhao; Wang, Weicong

2018-03-05

In this paper, thermochromic microcapsules were synthesized in situ polymerization with urea formaldehyde as shell material and thermochromic compounds as core material. The effects of emulsifying agent and conditions on surface morphology and particle size of microcapsules were studied. It was found that the size and surface morphology of microcapsules were strongly depending on stirring rate and the ratio of core to shell. The stable and small size spherical microcapsules with excellent transparency can be obtained at an emulsifying agent to core to shell ratio as 1:5:7.5 under mechanical stirring at 12 krpm for 15 min. Finally, the thermochromic property was discussed by loading microcapsules in wood and wood coatings. Results indicate that microcapsules can realize the thermochromic property while incorporated with wood and coatings, and could have high potential in smart material fabrication.

Light-scattering efficiency of starch acetate pigments as a function of size and packing density.

PubMed

Penttilä, Antti; Lumme, Kari; Kuutti, Lauri

2006-05-20

We study theoretically the light-scattering efficiency of paper coatings made of starch acetate pigments. For the light-scattering code we use a discrete dipole approximation method. The coating layer is assumed to consists of roughly equal-sized spherical pigments packed either at a packing density of 50% (large cylindrical slabs) or at 37% or 57% (large spheres). Because the scanning electron microscope images of starch acetate samples show either a particulate or a porous structure, we model the coatings in two complementary ways. The material can be either inside the constituent spheres (particulate case) or outside of those (cheeselike, porous medium). For the packing of our spheres we use either a simulated annealing or a dropping code. We can estimate, among other things, that the ideal sphere diameter is in the range 0.25-0.4 microm.

Light-scattering efficiency of starch acetate pigments as a function of size and packing density

NASA Astrophysics Data System (ADS)

Penttilä, Antti; Lumme, Kari; Kuutti, Lauri

2006-05-01

We study theoretically the light-scattering efficiency of paper coatings made of starch acetate pigments. For the light-scattering code we use a discrete dipole approximation method. The coating layer is assumed to consists of roughly equal-sized spherical pigments packed either at a packing density of 50% (large cylindrical slabs) or at 37% or 57% (large spheres). Because the scanning electron microscope images of starch acetate samples show either a particulate or a porous structure, we model the coatings in two complementary ways. The material can be either inside the constituent spheres (particulate case) or outside of those (cheeselike, porous medium). For the packing of our spheres we use either a simulated annealing or a dropping code. We can estimate, among other things, that the ideal sphere diameter is in the range 0.25-0.4 μm.

Friction and hardness of gold films deposited by ion plating and evaporation

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Spalvins, T.; Buckley, D. H.

1983-01-01

Sliding friction experiments were conducted with ion-plated and vapor-deposited gold films on various substrates in contact with a 0.025-mm-radius spherical silicon carbide rider in mineral oil. Hardness measurements were also made to examine the hardness depth profile of the coated gold on the substrate. The results indicate that the hardness is influenced by the depth of the gold coating from the surface. The hardness increases with an increase in the depth. The hardness is also related to the composition gradient in the graded interface between the gold coating and the substrate. The graded interface exhibited the highest hardness resulting from an alloy hardening effect. The coefficient of friction is inversely related to the hardness, namely, the load carrying capacity of the surface. The greater the hardness that the metal surface possesses, the lower is the coefficient of friction. The graded interface exhibited the lowest coefficient of friction.

Three-dimensional visualization of coated vesicle formation in fibroblasts

PubMed Central

1980-01-01

Fibroblasts apparently ingest low density lipoproteins (LDL) by a selective mechanism of receptor-mediated endocytosis involving the formation of coated vesicles from the plasma membrane. However, it is not known exactly how coated vesicles collect LDL receptors and pinch off from the plasma membrane. In this report, the quick-freeze, deep- etch, rotary-replication method has been applied to fibroblasts; it displays with unusual clarity the coats that appear under the plasma membrane at the start of receptor-mediated endocytosis. These coats appear to be polygonal networks of 7-nm strands or struts arranged into 30-nm polygons, most of which are hexagons but some of which are 5- and 7-sided rings. The proportion of pentagons in each network increases as the coated area of the plasma membrane puckers up from its planar configuration (where the network is mostly hexagons) to its most sharply curved condition as a pinched-off coated vesicle. Coats around the smallest vesicles (which are icosahedrons of hexagons and pentagons) appear only slightly different from "empty coats" purified from homogenized brain, which are less symmetrical baskets containing more pentagons than hexagons. A search for structural intermediates in this coat transformation allows a test of T. Kanaseki and K. Kadota's (1969. J. Cell Biol. 42:202--220.) original idea that an internal rearrangement in this basketwork from hexagons to pentagons could "power" coated vesicle formation. The most noteworthy variations in the typical hexagonal honeycomb are focal juxtapositions of 5- and 7-sided polygons at points of partial contraction and curvature in the basketwork. These appear to precede complete contraction into individual pentagons completely surrounded by hexagons, which is the pattern that characterizes the final spherical baskets around coated vesicles. PMID:6987244

Feasibility studies of concomitant administration of optimized formulation of probiotic-loaded Vancomycin hydrochloride pellets for colon delivery.

PubMed

Avachat, Amelia M; Shinde, Amol S

2016-01-01

Objective of this study was to develop Vancomycin HCl pellets loaded with Saccharomyces boulardii (S.b.) for pH-dependent system and CODES™ for augmenting the efficacy of Vancomycin HCl in the treatment of colitis. Pellets were prepared by extrusion-spheronization. In the pH-dependent system, the pellets were coated with Eudragit FS 30D. These pellets exhibited spherical form and a uniform surface coating. The CODES™ system consisted of three components: core containing mannitol, drug and probiotic, an inner acid-soluble coating layer, and an outer layer of enteric coating material. Statistical factorial design was used to optimize both formulations. Scanning electron micrographs of coated pellets revealed uniform coating. In vitro drug release of these coated pellets was studied sequentially in various buffers with (2%) and without rat cecal content for a period of 12 h. From the optimized pH-dependent formulation, F6 (20% w/w coating level and 15% w/v concentration of polymer), higher amount of probiotic was released in earlier time phase (first 5 h) as compared to the CODES™ and so R5 [containing acid-soluble inner coating layer (15% w/w coating level and 12% w/v concentration of Eudragit E100), and an outer layer of enteric coating material (12% w/w coating level and 10% w/v concentration of Eudragit L100)] was considered as the best formulation after confirming in vivo X-ray studies conducted on rabbits, suggesting that Vancomycin HCl and S.b. may be co-administered as pellets [CODES™] to enhance the effectiveness of Vancomycin HCl in the treatment of colitis without its associated side effects, which can only be confirmed after clinical trials.

In-depth analysis of switchable glycerol based polymeric coatings for cell sheet engineering.

PubMed

Becherer, Tobias; Heinen, Silke; Wei, Qiang; Haag, Rainer; Weinhart, Marie

2015-10-01

Scaffold-free cell sheet engineering using thermoresponsive substrates provides a promising alternative to conventional tissue engineering which in general employs biodegradable scaffold materials. We have previously developed a thermoresponsive coating with glycerol based linear copolymers that enables gentle harvesting of entire cell sheets. In this article we present an in-depth analysis of these thermoresponsive linear polyglycidyl ethers and their performance as coating for substrates in cell culture in comparison with commercially available poly(N-isopropylacrylamide) (PNIPAM) coated culture dishes. A series of copolymers of glycidyl methyl ether (GME) and glycidyl ethyl ether (EGE) was prepared in order to study their thermoresponsive properties in solution and on the surface with respect to the comonomer ratio. In both cases, when grafted to planar surfaces or spherical nanoparticles, the applied thermoresponsive polyglycerol coatings render the respective surfaces switchable. Protein adsorption experiments on copolymer coated planar surfaces with surface plasmon resonance (SPR) spectroscopy reveal the ability of the tested thermoresponsive coatings to be switched between highly protein resistant and adsorptive states. Cell culture experiments demonstrate that these thermoresponsive coatings allow for adhesion and proliferation of NIH 3T3 fibroblasts comparable to TCPS and faster than on PNIPAM substrates. Temperature triggered detachment of complete cell sheets from copolymer coated substrates was accomplished within minutes while maintaining high viability of the harvested cells. Thus such glycerol based copolymers present a promising alternative to PNIPAM as a thermoresponsive coating of cell culture substrates. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The influence of PEG-4000 and silica on crystal structure and magnetic properties of magnesium ferrite (MgFe{sub 2}O{sub 4}) nanoparticles

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

Puspitarum, Deska Lismawenning; Hermawan, Agung; Suharyadi, Edi, E-mail: esuharyadi@ugm.ac.id

2016-04-19

In this paper, reports the influence of polyethylene glycol (PEG-4000) and silica on crystal structure and magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles which is synthesized by the co-precipitation method. The particle size of before coated MgFe{sub 2}O{sub 4} was around 10.5 nm, and became 5.2 nm after PEG-4000 coating and 18.8 nm after silica coating. After coating, there were appeared new phases, α-Fe{sub 2}O{sub 3} (antiferromagnetic), SiO{sub 2} and γ-FeO(OH) which are paramagnetics. The second phase sample decreased responses to the external field. Transmission Electron Microscopy (TEM) morphology analysis on nanoparticles which was coated with PEG 4000 showed that the particles becomemore » more spherical, more dispersive, and less aglomerated. The magnetic hysteresis loops which was investigated with Vibrating Sample Magnetometer (VSM) indicated that coercivity of MgFe{sub 2}O{sub 4} was 120.7 Oe, and then decreased to 40.9 Oe after coating and 34.7 Oe for coating with PEG-4000 and silica, respectively. At 15 kOe, the magnetization value decreased from 2.69 emu/g to 0.96 emu/g after coating with PEG-4000 and increased 2.82 emu/g after silica coating. The result revealed the coating with both PEG-4000 and silica influence the magnetic properties of MgFe{sub 2}O{sub 4} nanoparticles.« less

Magnetic studies of SiO2 coated CoFe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Limaye, Mukta V.; Singh, Shashi B.; Das, Raja; Poddar, Pankaj; Abyaneh, Majid K.; Kulkarni, Sulabha K.

2017-11-01

Oleic acid capped CoFe2O4 nanoparticles which exhibit a high coercivity of ∼9.47 kOe at room temperature were coated with a robust coating of SiO2. We have used chemical synthesis method to obtain SiO2 coated CoFe2O4 nanoparticles with different weight percentages of CoFe2O4 in SiO2 (1.5, 3.1 and 4.8 wt.%). The morphological investigation of the coated nanoparticles by transmission electron microscopy shows that the particles are spherical with average size ∼160 nm. Infrared spectroscopy reveals that oleic acid capping on the surface of CoFe2O4 nanoparticles is retained after silica coating process. The complete coating of SiO2 on CoFe2O4 nanoparticles is confirmed by X-ray photoelectron spectroscopy as there is no signature of cobalt or iron ions on the surface. Magnetic measurements show that coercivity of SiO2 coated CoFe2O4 particles remains more or less unaffected as in CoFe2O4 nanoparticles at room temperature. In addition, the temperature dependent magnetic measurements show that at 5 K the CoFe2O4 and SiO2 coated 1.5 wt.% CoFe2O4 samples exhibit a very high value of coercivity (∼20 kOe) which is more than twice as compared to room temperature coercivity value (∼9.47 kOe). We conclude that silica coating in our study does not significantly affect the coercivity of CoFe2O4 nanoparticles.

Thermal Spray Deposition, Phase Stability and Mechanical Properties of La2Zr2O7/LaAlO3 Coatings

NASA Astrophysics Data System (ADS)

Lozano-Mandujano, D.; Poblano-Salas, C. A.; Ruiz-Luna, H.; Esparza-Esparza, B.; Giraldo-Betancur, A. L.; Alvarado-Orozco, J. M.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

2017-08-01

This paper deals with the deposition of La2Zr2O7 (LZO) and LaAlO3 (LAO) mixtures by air plasma spray (APS). The raw material for thermal spray, single phase LZO and LAO in a 70:30 mol.% ratio mixture was prepared from commercial metallic oxides by high-energy ball milling (HEBM) and high-temperature solid-state reaction. The HEBM synthesis route, followed by a spray-drying process, successfully produced spherical agglomerates with adequate size distribution and powder-flow properties for feeding an APS system. The as-sprayed coating consisted mainly of a crystalline LZO matrix and partially crystalline LAO, which resulted from the high cooling rate experienced by the molten particles as they impact the substrate. The coatings were annealed at 1100 °C to promote recrystallization of the LAO phase. The reduced elastic modulus and hardness, measured by nanoindentation, increased from 124.1 to 174.7 GPa and from 11.3 to 14.4 GPa, respectively, after the annealing treatment. These values are higher than those reported for YSZ coatings; however, the fracture toughness ( K IC) of the annealed coating was only 1.04 MPa m0.5.

Black carbon radiative forcing at TOA decreased during aging.

PubMed

Wu, Yu; Cheng, Tianhai; Zheng, Lijuan; Chen, Hao

2016-12-05

During aging processing, black carbon (also called soot) particles may tend to be mixed with other aerosols, and highly influence their radiative forcing. In this study, freshly emitted soot particles were simulated as fractal aggregates composed of small spherical primary monomers. After aging in the atmosphere, soot monomers were coated by a thinly layer of sulfate as thinly coated soot particles. These soot particles were entirely embedded into large sulfate particle by further aging, and becoming heavily coated soot particles. In clear-sky conditions, black carbon radiative forcing with different aging states were investigated for the bottom and top of atmosphere (BOA and TOA). The simulations showed that black carbon radiative forcing increased at BOA and decreased at TOA after their aging processes. Thinly and heavily coated states increased up to ~12% and ~35% black carbon radiative forcing at BOA, and black carbon radiative forcing at TOA can reach to ~20% and ~100% smaller for thinly and heavily coated states than those of freshly emitted states, respectively. The effect of aging states of black carbon radiative forcing was varied with surface albedo, aerosol optical depth and solar zenith angles. These findings would be helpful for the assessments of climate change.

Polyelectrolyte Multilayer Film Coated Silver Nanorods: An Effective Carrier System for Externally Activated Drug Delivery

NASA Astrophysics Data System (ADS)

Paramasivam, Gokul; Sharma, Varsha; Sundaramurthy, Anandhakumar

2017-08-01

Nanoparticle anisotropy offers unique functions and features in comparison with spherical nanoparticles (NPs) and makes anisotropic nanoparticles (ANPs) promising candidates in applications like drug delivery, imaging, biosensing and theranostics. Presence of surface active groups (e.g. amine, and carboxylate groups) on their surface provides binding sites for ligands or other biomolecules, and hence, this could be targeted for specific part or cells in our body. In the quest of such surface modification, functionalization of ANPs along Layer-by-Layer (LbL) coating of oppositely charged polyelectrolytes (PE) reduces cellular toxicity and promotes easy encapsulation of drugs. In this work, we report the silver nanorods (AgNRs) synthesis by adsorbate directed synthetic approach using cetyltrimethyl ammonium bromide (CTAB). The formed ANPs is investigated by scanning electron microscopy (SEM) and UV-Visible (UV-Vis) spectroscopy revealing the shaping of AgNRs of 3-16 nm aspect ratio with some presence of triangles. These NRs were further coated with bio polymers of chitosan (CH) and dextran sulphate (DS) through LbL approach and used for encapsulation of water soluble anti-bacterial drugs like ciprofloxacin hydrochloride (CFH). The encapsulation of drugs and profiles of drug release were investigated and compared to that of spherical silver nanoparticles (AgNPs). The added advantages of the proposed drug delivery system (DDS) can be externally activated to release the loaded drug and used as contrast agents for biological imaging under exposure to NIR light. Such system shows unique and attractive characteristics required for drug delivery and bioimaging thus offering the scope for further development as theranostic material.

Assessment of the suitability of GOCE-based geoid models for the unification of the North American vertical datums

NASA Astrophysics Data System (ADS)

Amjadiparvar, Babak; Sideris, Michael

2015-04-01

Precise gravimetric geoid heights are required when the unification of vertical datums is performed using the Geodetic Boundary Value Problem (GBVP) approach. Five generations of Global Geopotential Models (GGMs) derived from Gravity field and steady-state Ocean Circulation Explorer (GOCE) observations have been computed and released so far (available via IAG's International Centre for Global Earth Models, ICGEM, http://icgem.gfz-potsdam.de/ICGEM/). The performance of many of these models with respect to geoid determination has been studied in order to select the best performing model to be used in height datum unification in North America. More specifically, Release-3, 4 and 5 of the GOCE-based global geopotential models have been evaluated using GNSS-levelling data as independent control values. Comparisons against EGM2008 show that each successive release improves upon the previous one, with Release-5 models showing an improvement over EGM2008 in Canada and CONUS between spherical harmonic degrees 100 and 210. In Alaska and Mexico, a considerable improvement over EGM2008 was brought by the Release-5 models when used up to spherical harmonic degrees of 250 and 280, respectively. The positive impact of the Release-5 models was also felt when a gravimetric geoid was computed using the GOCE-based GGMs together with gravity and topography data in Canada. This geoid model, with appropriately modified Stokes kernel between spherical harmonic degrees 190 and 260, performed better than the official Canadian gravimetric geoid model CGG2013, thus illustrating the advantages of using the latest release GOCE-based models for vertical datum unification in North America.

Three-body spectrum in a finite volume: The role of cubic symmetry

DOE PAGES

Doring, M.; Hammer, H. -W.; Mai, M.; ...

2018-06-15

The three-particle quantization condition is partially diagonalized in the center-of-mass frame by using cubic symmetry on the lattice. To this end, instead of spherical harmonics, the kernel of the Bethe-Salpeter equation for particle-dimer scattering is expanded in the basis functions of different irreducible representations of the octahedral group. Such a projection is of particular importance for the three-body problem in the finite volume due to the occurrence of three-body singularities above breakup. Additionally, we study the numerical solution and properties of such a projected quantization condition in a simple model. It is shown that, for large volumes, these solutions allowmore » for an instructive interpretation of the energy eigenvalues in terms of bound and scattering states.« less

Three-body spectrum in a finite volume: The role of cubic symmetry

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

Doring, M.; Hammer, H. -W.; Mai, M.

The three-particle quantization condition is partially diagonalized in the center-of-mass frame by using cubic symmetry on the lattice. To this end, instead of spherical harmonics, the kernel of the Bethe-Salpeter equation for particle-dimer scattering is expanded in the basis functions of different irreducible representations of the octahedral group. Such a projection is of particular importance for the three-body problem in the finite volume due to the occurrence of three-body singularities above breakup. Additionally, we study the numerical solution and properties of such a projected quantization condition in a simple model. It is shown that, for large volumes, these solutions allowmore » for an instructive interpretation of the energy eigenvalues in terms of bound and scattering states.« less

A hybrid PSO-SVM-based method for predicting the friction coefficient between aircraft tire and coating

NASA Astrophysics Data System (ADS)

Zhan, Liwei; Li, Chengwei

2017-02-01

A hybrid PSO-SVM-based model is proposed to predict the friction coefficient between aircraft tire and coating. The presented hybrid model combines a support vector machine (SVM) with particle swarm optimization (PSO) technique. SVM has been adopted to solve regression problems successfully. Its regression accuracy is greatly related to optimizing parameters such as the regularization constant C , the parameter gamma γ corresponding to RBF kernel and the epsilon parameter \\varepsilon in the SVM training procedure. However, the friction coefficient which is predicted based on SVM has yet to be explored between aircraft tire and coating. The experiment reveals that drop height and tire rotational speed are the factors affecting friction coefficient. Bearing in mind, the friction coefficient can been predicted using the hybrid PSO-SVM-based model by the measured friction coefficient between aircraft tire and coating. To compare regression accuracy, a grid search (GS) method and a genetic algorithm (GA) are used to optimize the relevant parameters (C , γ and \\varepsilon ), respectively. The regression accuracy could be reflected by the coefficient of determination ({{R}2} ). The result shows that the hybrid PSO-RBF-SVM-based model has better accuracy compared with the GS-RBF-SVM- and GA-RBF-SVM-based models. The agreement of this model (PSO-RBF-SVM) with experiment data confirms its good performance.

On the radiative properties of soot aggregates - Part 2: Effects of coating

NASA Astrophysics Data System (ADS)

Liu, Fengshan; Yon, Jérôme; Bescond, Alexandre

2016-03-01

The effects of weakly absorbing material coating on soot have attracted considerable research attention in recent years due to the significant influence of such coating on soot radiative properties and the large differences predicted by different numerical models. Soot aggregates were first numerically generated using the diffusion limited cluster aggregation algorithm to produce fractal aggregates formed by log-normally distributed polydisperse spherical primary particles in point-touch. These aggregates were then processed by adding a certain amount of primary particle overlapping and necking to simulate the soot morphology observed from transmission electron microscopy images. After this process, a layer of WAM coating of different thicknesses was added to these more realistic soot aggregates. The radiative properties of these coated soot aggregates over the spectral range of 266-1064 nm were calculated by the discrete dipole approximation (DDA) using the spectrally dependent refractive index of soot for four aggregates containing Np=1, 20, 51 and 96 primary particles. The considered coating thicknesses range from 0% (no coating) up to 100% coating in terms of the primary particle diameter. Coating enhances both the particle absorption and scattering cross sections, with much stronger enhancement to the scattering one, as well as the asymmetry factor and the single scattering albedo. The absorption enhancement is stronger in the UV than in the visible and the near infrared. The simple corrections to the Rayleigh-Debye-Gans fractal aggregates theory for uncoated soot aggregates are found not working for coated soot aggregates. The core-shell model significantly overestimates the absorption enhancement by coating in the visible and the near infrared compared to the DDA results of the coated soot particle. Treating an externally coated soot aggregate as an aggregate formed by individually coated primary particles significantly underestimates the absorption enhancement by coating in the visible and the near infrared.

Microporous Ti implant compact coated with hydroxyapatite produced by electro-discharge-sintering and electrostatic-spray-deposition.

PubMed

Jo, Y J; Kim, Y H; Jo, Y H; Seong, J G; Chang, S Y; Van Tyne, C J; Lee, W H

2014-11-01

A single pulse of 1.5 kJ/0.7 g of atomized spherical Ti powder from 300 μF capacitor was applied to produce the porous-surfaced Ti implant compact by electro-discharge-sintering (EDS). A solid core surrounded by porous layer was self-consolidated by a discharge in the middle of the compact in 122 μsec. Average pore size, porosity, and compressive yield strength of EDS Ti compact were estimated to be about 68.2 μm, 25.5%, and 266.4 MPa, respectively. Coatings with hydroxyapatite (HAp) on the Ti compact were conducted by electrostatic-spray-deposition (ESD) method. As-deposited HAp coating was in the form of porous structure and consisted of HAp particles which were uniformly distributed on the Ti porous structure. By heat-treatment at 700 degrees C, HAp particles were agglomerated each other and melted to form a highly smooth and homogeneous HAp thin film consisted of equiaxed nano-scaled grains. Porous-surfaced Ti implant compacts coated with highly crystalline apatite phase were successfully obtained by using the EDS and ESD techniques.

Light scattering by marine algae: two-layer spherical and nonspherical models

NASA Astrophysics Data System (ADS)

Quirantes, Arturo; Bernard, Stewart

2004-11-01

Light scattering properties of algae-like particles are modeled using the T-matrix for coated scatterers. Two basic geometries have been considered: off-centered coated spheres and centered spheroids. Extinction, scattering and absorption efficiencies, plus scattering in the backward plane, are compared to simpler models like homogeneous (Mie) and coated (Aden-Kerker) models. The anomalous diffraction approximation (ADA), of widespread use in the oceanographic light-scattering community, has also been used as a first approximation, for both homogeneous and coated spheres. T-matrix calculations show that some light scattering values, such as extinction and scattering efficiencies, have little dependence on particle shape, thus reinforcing the view that simpler (Mie, Aden-Kerker) models can be applied to infer refractive index (RI) data from absorption curves. The backscattering efficiency, on the other hand, is quite sensitive to shape. This calls into question the use of light scattering techniques where the phase function plays a pivotal role, and can help explain the observed discrepancy between theoretical and experimental values of the backscattering coefficient in observed in oceanic studies.

Modeling pressure-driven assembly of polymer coated nanoparticles

NASA Astrophysics Data System (ADS)

Lane, J. Matthew D.; Salerno, K. Michael; Grest, Gary S.; Fan, Hongyou

2017-06-01

High-pressure experiments have successfully produced a variety of gold nanostructures by compressing polymer coated spherical nanoparticles. We apply atomistic simulation to understand the role of the soft polymer response in determining the pressure-driven assembly of gold nanostructures. Quasi-isentropic experiments have shown that 1D, 2D and 3D nanostructures can be formed and recovered from dynamic compression of fcc superlattices of alkanethiol-coated gold nanocrystals on Sandia's Veloce pulsed power accelerator. Molecular modeling has shown that the dimensionality of the final structures depends on the orientation of the superlattice and the uniaxial loading. We describe the role of coating ligand length and grafting density, on ligand migration and deformation processes during pressure-driven coalescence of the cores into permanent nanowires, nanosheets and 3D structures. The role of uniaxial vs isotropic pressure and the effects of compression along various superlattice orientations will be discussed. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Microencapsulation of anthocyanin-rich black soybean coat extract by spray drying using maltodextrin, gum Arabic and skimmed milk powder.

PubMed

Kalušević, Ana; Lević, Steva; Čalija, Bojan; Pantić, Milena; Belović, Miona; Pavlović, Vladimir; Bugarski, Branko; Milić, Jela; Žilić, Slađana; Nedović, Viktor

2017-08-01

Black soybean coat is insufficiently valorised food production waste rich in anthocyanins. The goal of the study was to examine physicochemical properties of spray dried extract of black soybean coat in regard to carrier materials: maltodextrin, gum Arabic, and skimmed milk powder. Maltodextrin and gum Arabic-based microparticles were spherical and non-porous while skimmed milk powder-based were irregularly shaped. Low water activity of microparticles (0.31-0.33), good powders characteristics, high solubility (80.3-94.3%) and encapsulation yields (63.7-77.0%) were determined. All microparticles exhibited significant antioxidant capacity (243-386 μmolTE/g), good colour stability after three months of storage and antimicrobial activity. High content of total anthocyanins, with cyanidin-3-glucoside as predominant, were achieved. In vitro release of anthocyanins from microparticles was sustained, particularly from gum Arabic-based. These findings suggest that proposed simple eco-friendly extraction and microencapsulation procedures could serve as valuable tools for valorisation and conversion of black soybean coat into highly functional and stable food colourant.

Fabrication of coated bovine serum albumin (BSA)-epigallocatechin gallate (EGCG) nanoparticles and their transport across monolayers of human intestinal epithelial Caco-2 cells.

PubMed

Li, Zheng; Ha, Jungheun; Zou, Tao; Gu, Liwei

2014-06-01

The bovine serum albumin (BSA)-epigallocatechin gallate (EGCG) nanoparticles were fabricated using a desolvation method, and coated with poly-ε-lysine or chitosan. BSA-EGCG nanoparticles (BEN), poly-ε-lysine coated BSA-EGCG nanoparticles (PBEN), and chitosan coated BSA-EGCG nanoparticles (CBEN) had a spherical morphology and a size of 186, 259, and 300 nm, respectively. The loading efficiency of EGCG in these nanoparticles was 32.3%, 35.4%, and 32.7%, whereas the loading capacity was 18.9%, 17.0%, and 16.0% (w/w), respectively. Poly-ε-lysine or chitosan coating prevented the aggregation of nanoparticles at pH 4.5-5.0. However, they caused particle aggregation at pH 6.5-7.0. BEN had negative zeta-potentials between pH 4.5 and 6.0. Poly-ε-lysine or chitosan coating changed the zeta-potentials to positive. The release study of EGCG from the nanoparticles in the simulated gastric or intestinal fluid with or without digestive enzymes showed that poly-ε-lysine and chitosan coatings delayed EGCG release from the nanoparticles. Poly-ε-lysine or chitosan coating improved the stability of EGCG during storage at 60 °C compared with EGCG in the uncoated particles. EGCG in BEN, PBEN, and CBEN had a decreasing apparent permeability coefficient (Papp) on Caco-2 monolayers, whereas pure EGCG showed relatively stable Papp during the incubation over time. EGCG in CBEN showed significantly higher Papp, suggesting that chitosan coated BSA-EGCG nanoparticles may improve the absorption of EGCG.

Genetic variation of coat protein gene among the isolates of Rice tungro spherical virus from tungro-endemic states of the India.

PubMed

Mangrauthia, Satendra K; Malathi, P; Agarwal, Surekha; Ramkumar, G; Krishnaveni, D; Neeraja, C N; Madhav, M Sheshu; Ladhalakshmi, D; Balachandran, S M; Viraktamath, B C

2012-06-01

Rice tungro disease, one of the major constraints to rice production in South and Southeast Asia, is caused by a combination of two viruses: Rice tungro spherical virus (RTSV) and Rice tungro bacilliform virus (RTBV). The present study was undertaken to determine the genetic variation of RTSV population present in tungro endemic states of Indian subcontinent. Phylogenetic analysis based on coat protein sequences showed distinct divergence of Indian RTSV isolates into two groups; one consisted isolates from Hyderabad (Andhra Pradesh), Cuttack (Orissa), and Puducherry and another from West Bengal, Coimbatore (Tamil Nadu), and Kanyakumari (Tamil Nadu). The results obtained from phylogenetic study were further supported with the SNPs (single nucleotide polymorphism), INDELs (insertion and deletion) and evolutionary distance analysis. In addition, sequence difference count matrix revealed 2-68 nucleotides differences among all the Indian RTSV isolates taken in this study. However, at the protein level these differences were not significant as revealed by Ka/Ks ratio calculation. Sequence identity at nucleotide and amino acid level was 92-100% and 97-100%, respectively, among Indian isolates of RTSV. Understanding of the population structure of RTSV from tungro endemic regions of India would potentially provide insights into the molecular diversification of this virus.

Metal Alloy ICF Capsules Created by Electrodeposition

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

Horwood, Corie; Stadermann, Michael; Bunn, Thomas L.

Electrochemical deposition is an attractive alternative to physical vapor deposition and micromachining to produce metal capsules for inertial confinement fusion (ICF). Electrochemical deposition (also referred to as electrodeposition or plating) is expected to produce full-density metal capsules without seams or inclusions of unwanted atomic constituents, the current shortcomings of micromachine and physical vapor deposition, respectively. In this paper, we discuss new cathode designs that allow for the rapid electrodeposition of gold and copper alloys on spherical mandrels by making transient contact with the constantly moving spheres. Electrodeposition of pure gold, copper, platinum, and alloys of gold-copper and gold-silver are demonstrated,more » with nonporous coatings of >40 µm achieved in only a few hours of plating. The surface roughness of the spheres after electrodeposition is comparable to the starting mandrel, and the coatings appear to be fully dense with no inclusions. A detailed understanding of the electrodeposition conditions that result in different alloy compositions and plating rates will allow for the electrodeposition of graded alloys on spheres in the near future. Finally, this report on the electrodeposition of metals on spherical mandrels is an important first step toward the fabrication of graded-density metal capsules for ICF experiments at the National Ignition Facility.« less

Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries.

PubMed

Yang, Shiliu; Hu, Mingjun; Xi, Liujiang; Ma, Ruguang; Dong, Yucheng; Chung, C Y

2013-09-25

A microspherical, hollow LiFePO4 (LFP) cathode material with polycrystal structure was simply synthesized by a solvothermal method using spherical Li3PO4 as the self-sacrificed template and FeCl2·4H2O as the Fe(2+) source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the LFP micro hollow spheres have a quite uniform size of ~1 μm consisting of aggregated nanoparticles. The influences of solvent and Fe(2+) source on the phase and morphology of the final product were chiefly investigated, and a direct ion exchange reaction between spherical Li3PO4 templates and Fe(2+) ions was firstly proposed on the basis of the X-ray powder diffraction (XRD) transformation of the products. The LFP nanoparticles in the micro hollow spheres could finely coat a uniform carbon layer ~3.5 nm by a glucose solution impregnating-drying-sintering process. The electrochemical measurements show that the carbon coated LFP materials could exhibit high charge-discharge capacities of 158, 144, 125, 101, and even 72 mAh g(-1) at 0.1, 1, 5, 20, and 50 C, respectively. It could also maintain 80% of the initial discharge capacity after cycling for 2000 times at 20 C.

Synthesis of Elongated Microcapsules

NASA Technical Reports Server (NTRS)

Li, Wenyan; Buhrow, Jerry; Calle, Luz M.

2011-01-01

One of the factors that influence the effectiveness of self-healing in functional materials is the amount of liquid healing agents that can be delivered to the damaged area. The use of hollow tubes or fibers and the more sophisticated micro-vascular networks has been proposed as a way to increase the amount of healing agents that can be released when damage is inflicted. Although these systems might be effective in some specific applications, they are not practical for coatings applications. One possible practical way to increase the healing efficiency is to use microcapsules with high-aspect-ratios, or elongated microcapsules. It is understood that elongated microcapsules will be more efficient because they can release more healing agent than a spherical microcapsule when a crack is initiated in the coating. Although the potential advantage of using elongated microcapsules for self healing applications is clear, it is very difficult to make elongated microcapsules from an emulsion system because spherical microcapsules are normally formed due to the interfacial tension between the dispersed phase and the continuous phase. This paper describes the two methods that have been developed by the authors to synthesize elongated microcapsules. The first method involves the use of an emulsion with intermediate stability and the second involves the application of mechanical shear conditions to the emulsion.

Metal Alloy ICF Capsules Created by Electrodeposition

DOE PAGES

Horwood, Corie; Stadermann, Michael; Bunn, Thomas L.

2017-12-04

Electrochemical deposition is an attractive alternative to physical vapor deposition and micromachining to produce metal capsules for inertial confinement fusion (ICF). Electrochemical deposition (also referred to as electrodeposition or plating) is expected to produce full-density metal capsules without seams or inclusions of unwanted atomic constituents, the current shortcomings of micromachine and physical vapor deposition, respectively. In this paper, we discuss new cathode designs that allow for the rapid electrodeposition of gold and copper alloys on spherical mandrels by making transient contact with the constantly moving spheres. Electrodeposition of pure gold, copper, platinum, and alloys of gold-copper and gold-silver are demonstrated,more » with nonporous coatings of >40 µm achieved in only a few hours of plating. The surface roughness of the spheres after electrodeposition is comparable to the starting mandrel, and the coatings appear to be fully dense with no inclusions. A detailed understanding of the electrodeposition conditions that result in different alloy compositions and plating rates will allow for the electrodeposition of graded alloys on spheres in the near future. Finally, this report on the electrodeposition of metals on spherical mandrels is an important first step toward the fabrication of graded-density metal capsules for ICF experiments at the National Ignition Facility.« less

PEG-stearate coated solid lipid nanoparticles as levothyroxine carriers for oral administration

NASA Astrophysics Data System (ADS)

Kashanian, Soheila; Rostami, Elham

2014-03-01

In this study, poly ethylene glycol 100 stearate (PEG 100-S) was used to prepare coated solid lipid nanoparticles with loading levothyroxine sodium (levo-loaded PEG 100-S-coated SLNs) by microemulsification technique. Evaluation of the release kinetic of prepared colloidal carriers was conducted. The particle size and zeta potential of levo-loaded PEG 100-S-coated SLNs have been measured to be 187.5 nm and -23.0 mV, respectively, using photon correlation spectroscopy (PCS). Drug entrapment efficiency (EE) was calculated to be 99 %. Differential scanning calorimetry indicated that the majority of drug loaded in PEG 100-S-coated SLNs were in amorphous state which could be considered desirable for drug delivery. The purpose of this study was to develop a new nanoparticle system, consisting lipid nanoparticles coated with PEG 100-S. The modification procedure led to a reduction in the zeta potential values, varying from -40.0 to -23.0 mV for the uncoated and PEG-coated SLNs, respectively. Stability results of the nanoparticles in gastric and intestinal media show that the low pH of the gastric medium is responsible for the critical aggregation and degradation of the uncoated lipid nanoparticles. PEG 100-S-coated SLNs were more stable due to their polymer coating layer which prevented aggregation of SLNs. Consequently, it is possible that the PEG surrounds the particles reducing the attachment of enzymes and further degradation of the triglyceride cores. Shape and surface morphology of particles were determined by transition electron microscopy and scanning electron microscopy that revealed spherical shape of nanoparticles. In vitro drug release of PEG 100-S-coated SLNs was characterized using diffusion cell which showed a controlled release for drug.

Particle Morphology Effects on Flow Characteristics of PS304 Plasma Spray Coating Feedstock Powder Blend

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; DellaCorte, Christopher; Eylon, Daniel

2002-01-01

The effects of BaF2-CaF 2 particle morphology on PS304 feedstock powder flow ability have been investigated. BaF2-CaF2 eutectic powders were fabricated by comminution (angular) and by gas atomization (spherical). The fluoride powders were added incrementally to the other powder constituents of the PS304 feedstock: nichrome, chromia, and silver powders. A linear relationship between flow time and concentration of BaF2-CaF2 powder was found. Flow of the powder blend with spherical BaF2-CaF2 was better than the angular BaF2-CaF2. Flow ability of the powder blend with angular fluorides decreased linearly with increasing fluoride concentration. Flow of the powder blend with spherical fluorides was independent of fluoride concentration. Results suggest that for this material blend, particle morphology plays a significant role in powder blend flow behavior, offering potential methods to improve powder flow ability and enhance the commercial potential. These findings may have applicability to other difficult-to-flow powders such as cohesive ceramics.

Preparation of Ultrahigh Molecular Weight Polyethylene/Graphene Nanocomposite In situ Polymerization via Spherical and Sandwich Structure Graphene/Sio2 Support

NASA Astrophysics Data System (ADS)

Su, Enqi; Gao, Wensheng; Hu, Xinjun; Zhang, Caicai; Zhu, Bochao; Jia, Junji; Huang, Anping; Bai, Yongxiao

2018-04-01

Reduced graphene oxide/SiO2 (RGO/SiO2) serving as a novel spherical support for Ziegler-Natta (Z-N) catalyst is reported. The surface and interior of the support has a porous architecture formed by RGO/SiO2 sandwich structure. The sandwich structure is like a brick wall coated with a graphene layer of concreted as skeleton which could withstand external pressures and endow the structure with higher support stabilities. After loading the Z-N catalyst, the active components anchor on the surface and internal pores of the supports. When the ethylene molecules meet the active centers, the molecular chains grow from the surface and internal catalytic sites in a regular and well-organized way. And the process of the nascent molecular chains filled in the sandwich structure polymerization could ensure the graphene disperse uniformly in the polymer matrix. Compared with traditional methods, the porous spherical graphene support of this strategy has far more advantages and could maintain an intrinsic graphene performance in the nanocomposites.

Organ-specific SPECT activity calibration using 3D printed phantoms for molecular radiotherapy dosimetry.

PubMed

Robinson, Andrew P; Tipping, Jill; Cullen, David M; Hamilton, David; Brown, Richard; Flynn, Alex; Oldfield, Christopher; Page, Emma; Price, Emlyn; Smith, Andrew; Snee, Richard

2016-12-01

Patient-specific absorbed dose calculations for molecular radiotherapy require accurate activity quantification. This is commonly derived from Single-Photon Emission Computed Tomography (SPECT) imaging using a calibration factor relating detected counts to known activity in a phantom insert. A series of phantom inserts, based on the mathematical models underlying many clinical dosimetry calculations, have been produced using 3D printing techniques. SPECT/CT data for the phantom inserts has been used to calculate new organ-specific calibration factors for (99m) Tc and (177)Lu. The measured calibration factors are compared to predicted values from calculations using a Gaussian kernel. Measured SPECT calibration factors for 3D printed organs display a clear dependence on organ shape for (99m) Tc and (177)Lu. The observed variation in calibration factor is reproduced using Gaussian kernel-based calculation over two orders of magnitude change in insert volume for (99m) Tc and (177)Lu. These new organ-specific calibration factors show a 24, 11 and 8 % reduction in absorbed dose for the liver, spleen and kidneys, respectively. Non-spherical calibration factors from 3D printed phantom inserts can significantly improve the accuracy of whole organ activity quantification for molecular radiotherapy, providing a crucial step towards individualised activity quantification and patient-specific dosimetry. 3D printed inserts are found to provide a cost effective and efficient way for clinical centres to access more realistic phantom data.

Stable computations with flat radial basis functions using vector-valued rational approximations

NASA Astrophysics Data System (ADS)

Wright, Grady B.; Fornberg, Bengt

2017-02-01

One commonly finds in applications of smooth radial basis functions (RBFs) that scaling the kernels so they are 'flat' leads to smaller discretization errors. However, the direct numerical approach for computing with flat RBFs (RBF-Direct) is severely ill-conditioned. We present an algorithm for bypassing this ill-conditioning that is based on a new method for rational approximation (RA) of vector-valued analytic functions with the property that all components of the vector share the same singularities. This new algorithm (RBF-RA) is more accurate, robust, and easier to implement than the Contour-Padé method, which is similarly based on vector-valued rational approximation. In contrast to the stable RBF-QR and RBF-GA algorithms, which are based on finding a better conditioned base in the same RBF-space, the new algorithm can be used with any type of smooth radial kernel, and it is also applicable to a wider range of tasks (including calculating Hermite type implicit RBF-FD stencils). We present a series of numerical experiments demonstrating the effectiveness of this new method for computing RBF interpolants in the flat regime. We also demonstrate the flexibility of the method by using it to compute implicit RBF-FD formulas in the flat regime and then using these for solving Poisson's equation in a 3-D spherical shell.

Metal-coated magnetic nanoparticles in an optically active medium: A nonreciprocal metamaterial

NASA Astrophysics Data System (ADS)

Christofi, Aristi; Stefanou, Nikolaos

2018-03-01

We report on the optical response of a nonreciprocal bianisotropic metamaterial, consisting of spherical, metal-coated magnetic nanoparticles embedded in an optically active medium, thus combining gyrotropy, plasmonic resonances, and chirality in a versatile design. The corresponding effective medium is deduced by an appropriate two-step generalized Maxwell-Garnett homogenization scheme. The associated photonic band structure and transmission spectra are obtained through a six-vector formulation of Maxwell equations, which provides an efficient framework for general bianisotropic structures going beyond existing approaches that involve cumbersome nonlinear eigenvalue problems. Our results, analyzed and discussed in the light of group theory, provide evidence that the proposed metamaterial exhibits some remarkable frequency-tunable properties, such as strong, plasmon-enhanced nonreciprocal polarization azimuth rotation and magnetochiral dichroism.

Multishell inertial confinement fusion target

DOEpatents

Holland, James R.; Del Vecchio, Robert M.

1984-01-01

A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reaction accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

Multishell inertial confinement fusion target

DOEpatents

Holland, James R.; Del Vecchio, Robert M.

1987-01-01

A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reactions accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

Photothermal effect of gold nanostars inkjet-printed on coated paper substrate under near-infrared irradiation

NASA Astrophysics Data System (ADS)

Borzenkov, Mykola; Chirico, Giuseppe; Collini, Maddalena; Määttänen, Anni; Ihalainen, Petri; Cabrini, Elisa; Dacarro, Giacomo; Pallavicini, Piersandro

2016-04-01

The research and development of personalized medical treatments is increasing steadily fostered by its large societal impact. The ability of non-spherical gold nanoparticles to locally and efficiently release heat when irradiated in Near Infrared (NIR) wavelength region is a promising tool for photothermal medical therapies. In the present work, stable inks containing PEGylated gold nanostars (GNS) were obtained and inkjet-printed on a pigment coated paper substrate. Significant photothermal effect of the printed patterns was observed under Near Infrared (NIR) excitation of the Localized Surface Plasmon Resonance (LSPR) of the GNS. These preliminary results support, in perspective, the application of printed GNS patterns for thermal medical treatments either by direct localized heating, or by temperature triggered drug release.

Anania Shirakatsi's Cosmographical and Natural Philosophical Views

NASA Astrophysics Data System (ADS)

Danielyan, Eduard

2014-10-01

The observation of the heaven and celestial bodies has taken place since ancient times in the Armenian Highland. The notions of the sphericity of the Earth and celestial bodies, and other theses (about elements, comparative sizes of celestial bodies, antipodes, earthquakes, criticism of astrology, etc.) were reflected and elaborated in "Cosmography" of Anania Shirakatsi (VII century AD), as well as "Ashkharhatsoyts" ("Geography") of Movses Khorenatsi (V century AD) and his continuer Anania Shirakatsi. The road of observation and study of the Milky Way - the fundamental kernel of the development of astronomy - has led the human mind to galaxies, the cognition of the infinite capabilities of the development of matter, that is to say, from the studies of the elements constituting the Earth and other spherical bodies in the Universe (studied by Aristotle) to the Heliocentric system by Copernicus (1473-1543), from the cosmogonic ideas of Democritus (460-370 BC) about the multitude of worlds and the character of the Milky Way and their reflection in natural philosophic views of Anania Shirakatsi to the discovery of non-stationary objects and processes in the Universe owing to the activity of the nuclei of galaxies, according to the cosmogonic conception of academician Victor Ambartsumyan. Anania Shirakatsi's scientific heritage greatly contributed to the development of Armenian and world natural scientific thought.

Characterizing the collapse of a cavitation bubble cloud in a focused ultrasound field

NASA Astrophysics Data System (ADS)

Maeda, Kazuki; Colonius, Tim

2017-11-01

We study the coherent collapse of clouds of cavitation bubbles generated by the passage of a pulse of ultrasound. In order to characterize such collapse, we conduct a parametric study on the dynamics of a spherical bubble cloud with a radius of r = O(1) mm interacting with traveling ultrasound waves with an amplitude of pa = O(102 -106) Pa and a wavelength of λ = O(1 - 10) mm in water. Bubbles with a radius of O(10) um are treated as spherical, radially oscillating cavities dispersed in continuous liquid phase. The volume of Lagrangian point bubbles is mapped with a regularization kernel as void fraction onto Cartesian grids that defines the Eulerian liquid phase. The flow field is solved using a WENO-based compressible flow solver. We identified that coherent collapse occurs when λ >> r , regardless of the value of pa, while it only occurs for sufficiently high pa when λ r . For the long wavelength case, the results agree with the theory on linearized dynamics of d'Agostino and Brennen (1989). We extend the theory to short wave length case. Finally, we analyze the far-field acoustics scattered by individual bubbles and correlate them with the cloud collapse, for applications to acoustic imaging of bubble cloud dynamics. Funding supported by NIH P01-DK043881.

Surface spins disorder in uncoated and SiO2 coated maghemite nanoparticles

NASA Astrophysics Data System (ADS)

Zeb, F.; Nadeem, K.; Shah, S. Kamran Ali; Kamran, M.; Gul, I. Hussain; Ali, L.

2017-05-01

We studied the surface spins disorder in uncoated and silica (SiO2) coated maghemite (γ-Fe2O3) nanoparticles using temperature and time dependent magnetization. The average crystallite size for SiO2 coated and uncoated nanoparticles was about 12 and 29 nm, respectively. Scanning electron microscopy (SEM) showed that the nanoparticles are spherical in shape and well separated. Temperature scans of zero field cooled (ZFC)/field cooled (FC) magnetization measurements showed lower average blocking temperature (TB) for SiO2 coated maghemite nanoparticles as compared to uncoated nanoparticles. The saturation magnetization (Ms) of SiO2 coated maghemite nanoparticles was also lower than the uncoated nanoparticles and is attributed to smaller average crystallite size of SiO2 coated nanoparticles. For saturation magnetization vs. temperature data, Bloch's law (M(T)= M(0).(1- BTb)) was fitted well for both uncoated and SiO2 coated nanoparticles and yields: B =3×10-7 K-b, b=2.22 and B=0.0127 K-b, b=0.57 for uncoated and SiO2 coated nanoparticles, respectively. Higher value of B for SiO2 coated nanoparticles depicts decrease in exchange coupling due to enhanced surface spins disorder (broken surface bonds) as compared to uncoated nanoparticles. The Bloch's exponent b was decreased for SiO2 coated nanoparticles which is due to their smaller average crystallite size or finite size effects. Furthermore, a sharp increase of coercivity at low temperatures (<25 K) was observed for SiO2 coated nanoparticles which is also due to contribution of increased surface anisotropy or frozen surface spins in these smaller nanoparticles. The FC magnetic relaxation data was fitted to stretched exponential law which revealed slower magnetic relaxation for SiO2 coated nanoparticles. All these measurements revealed smaller average crystallite size and enhanced surface spins disorder in SiO2 coated nanoparticles than in uncoated γ-Fe2O3 nanoparticles.

Combined Effect of Long Processing Time and Na2SiF6 on the Properties of PEO Coatings Formed on AZ91D

NASA Astrophysics Data System (ADS)

Rehman, Zeeshan Ur; Koo, Bon Heun

2016-08-01

In this study, protective ceramic coatings were prepared on AZ91D magnesium alloy by plasma electrolytic oxidation (PEO) to improve the corrosion and mechanical properties of AZ91D magnesium alloy. The process was conducted in silicate-fluoride-based electrolyte solution. It was found that the average micro-hardness of the coating was significantly increased with an increase in the PEO processing time. The highest value of the average micro-hardness ~1271.2 HV was recorded for 60-min processing time. The phase analysis of the coatings indicated that they were mainly composed of Mg2SiO4, MgO, and MgF2 phases. The surface and cross-sectional study demonstrated that porosity was largely reduced with processing time, together with the change in pore geometry from irregular to spherical shape. The results of the polarization test in 3.5 wt.% NaCl solution revealed that aggressive corrosion took place for 5-min sample; however, the corrosion current was noticeably decreased to 0.43 × 10-7 A/cm2 for the 60-min-coated sample. The superior nobility and hardness for long processing time are suggested to be due to the dense and highly thick coating, coupled with the presence of MgF2 phase.

SiO2-coated LiNi0.915Co0.075Al0.01O2 cathode material for rechargeable Li-ion batteries.

PubMed

Zhou, Pengfei; Zhang, Zhen; Meng, Huanju; Lu, Yanying; Cao, Jun; Cheng, Fangyi; Tao, Zhanliang; Chen, Jun

2016-11-24

We reported a one-step dry coating of amorphous SiO 2 on spherical Ni-rich layered LiNi 0.915 Co 0.075 Al 0.01 O 2 (NCA) cathode materials. Combined characterization of XRD, EDS mapping, and TEM indicates that a SiO 2 layer with an average thickness of ∼50 nm was uniformly coated on the surface of NCA microspheres, without inducing any change of the phase structure and morphology. Electrochemical tests show that the 0.2 wt% SiO 2 -coated NCA material exhibits enhanced cyclability and rate properties, combining with better thermal stability compared with those of pristine NCA. For example, 0.2 wt% SiO 2 -coated NCA delivers a high specific capacity of 181.3 mA h g -1 with a capacity retention of 90.7% after 50 cycles at 1 C rate and 25 °C. Moreover, the capacity retention of this composite at 60 °C is 12.5% higher than that of pristine NCA at 1 C rate after 50 cycles. The effects of SiO 2 coating on the electrochemical performance of NCA are investigated by EIS, CV, and DSC tests, the improved performance is attributed to the surface coating layer of amorphous SiO 2 , which effectively suppresses side reactions between NCA and electrolytes, decreases the SEI layer resistance, and retards the growth of charge-transfer resistance, thus enhancing structural and cycling stability of NCA.

Calcium phosphate/chitosan composite coating: Effect of different concentrations of Mg2+ in the m-SBF on its bioactivity

NASA Astrophysics Data System (ADS)

Zhang, Jie; Dai, Changsong; Wei, Jie; Wen, Zhaohui; Zhang, Shujuan; Lin, Lemin

2013-09-01

The purpose of this study was to investigate the effect of different concentration of Mg2+ in a modified simulated body fluid (m-SBF) on the bioactivity of calcium phosphate/chitosan composite coating. Calcium phosphate/chitosan composite coating was prepared on graphite substrate via electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). The obtained samples were soaked in the m-SBF containing different concentration of Mg2+ for different times. And then, the composite coatings were assessed using X-ray diffractometer (XRD), Fourier-transformed infrared spectroscopy (FTIR), Raman spectra, and scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS). The soaking solution was evaluated by inductively coupled plasma optical emission spectrometer (ICP-OES) test. The analytical results showed that hydroxyapatite (HA) and bone-like apatite (HCA) grew on the surface of calcium phosphate/chitosan composite coating after incubation in different m-SBF. With Mg2+ concentration in m-SBF increased from 1× Mg to 10× Mg, HA in the composite coating first presented a dissolving process and then a precipitating one slowly, while HCA presented a growing trend, continuously. The increasing of Mg2+ concentration in the m-SBF inhibited the total growing process of HA and HCA as a whole. The structure of the composite coating changed from spherical into irregular morphology with the concentration of Mg2+ increasing from 1× Mg to 10× Mg. Over all, with the Mg2+ concentration increasing, the bioactivity of calcium phosphate/chitosan composite coating tended to decrease.

Indium nanoparticles for ultraviolet surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Das, Rupali; Soni, R. K.

2018-05-01

Ultraviolet Surface-enhanced Raman spectroscopy (UVSERS) has emerged as an efficient molecular spectroscopy technique for ultra-sensitive and ultra-low detection of analyte concentration. The generic SERS substrates based on gold and silver nanostructures have been extensively explored for high local electric field enhancement only in visible-NIR region of the electromagnetic spectrum. The template synthesis of controlled nanoscale size metallic nanostructures supporting localized surface plasmon resonance (LSPR) in the UV region have been recently explored due to their ease of synthesis and potential applications in optoelectronic, catalysis and magnetism. Indium (In0) nanoparticles exhibit active surface plasmon resonance (SPR) in ultraviolet (UV) and deep-ultaviolet (DUV) region with optimal absorption losses. This extended accessibility makes indium a promising material for UV plasmonic, chemical sensing and more recently in UV-SERS. In this work, spherical indium nanoparticles (In NPs) were synthesized by modified polyol reduction method using NaBH4 having local surface plasmon resonance near 280 nm. The as-synthesized spherical In0 nanoparticles were then coated with thin silica shells of thickness ˜ 5nm by a modified Stober method protecting the nanoparticles from agglomeration, direct contact with the probed molecules as well as prevent oxidation of the nanoparticles. Morphological evolution of In0 nanoparticles and SiO2 coating were characterized by transmission electron microscope (TEM). An enhanced near resonant shell-isolated SERS activity from thin film of tryptophan (Tryp) molecules deposited on indium coated substrates under 325nm UV excitation was observed. Finite difference time domain (FDTD) method is employed to comprehend the experimental results and simulate the electric field contours which showed amplified electromagnetic field localized around the nanostructures. The comprehensive analysis indicates that indium is a promising alternate exogenous contrast agent for efficient Raman spectroscopy from molecules.

Neutronics Studies of Uranium-bearing Fully Ceramic Micro-encapsulated Fuel for PWRs

DOE PAGES

George, Nathan M.; Maldonado, G. Ivan; Terrani, Kurt A.; ...

2014-12-01

Our study evaluated the neutronics and some of the fuel cycle characteristics of using uranium-based fully ceramic microencapsulated (FCM) fuel in a pressurized water reactor (PWR). Specific PWR lattice designs with FCM fuel have been developed that are expected to achieve higher specific burnup levels in the fuel while also increasing the tolerance to reactor accidents. The SCALE software system was the primary analysis tool used to model the lattice designs. A parametric study was performed by varying tristructural isotropic particle design features (e.g., kernel diameter, coating layer thicknesses, and packing fraction) to understand the impact on reactivity and resultingmore » operating cycle length. Moreover, to match the lifetime of an 18-month PWR cycle, the FCM particle fuel design required roughly 10% additional fissile material at beginning of life compared with that of a standard uranium dioxide (UO 2) rod. Uranium mononitride proved to be a favorable fuel for the fuel kernel due to its higher heavy metal loading density compared with UO 2. The FCM fuel designs evaluated maintain acceptable neutronics design features for fuel lifetime, lattice peaking factors, and nonproliferation figure of merit.« less

Impact of High-Z Coatings on the Ablation Pressure of Laser Driven Targets.

NASA Astrophysics Data System (ADS)

Mostovych, Andrew; Oh, Jaechul; Schmitt, Andrew; Weaver, James

2007-11-01

Recent hydrodynamic experiments [1] with planar high-Z coated targets at the Naval Research Laboratory and spherical implosion experiments with high-Z coated shell targets [2] at the Omega facility all show significant improvement in target stability as a result of the high-Z coatings. For better understanding of the hydrodynamic processes it is important to know the changes in ablation pressure as a result of the high-Z layers. Using the Nike Laser, we have conducted new experiments to measure the change in shock speed of planar CH targets that are irradiated with and without the presence of a 200 Ang. gold high-Z coating. The evolution of shock propagation inside the targets is diagnosed with VISAR probing while average shock velocities are also measured by shock breakout detection from the stepped rear surface of the targets. We find that the high-Z layers produce a time dependent ablation pressure which is detected via the observation of non-steady shocks in the targets. Experimental results and comparisons to hydrodynamic simulations will be presented. Work supported by U. S. Department of Energy. [1] S.P. Obenschain et al., Phys. Plasmas 9, 2234 (2002). [2] A.N. Mostovych et al., APS Abstracts DPPFO3002M, (2005).

Key results from irradiation and post-irradiation examination of AGR-1 UCO TRISO fuel

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

Demkowicz, Paul A.; Hunn, John D.; Petti, David A.

The AGR-1 irradiation experiment was performed as the first test of tristructural isotropic (TRISO) fuel in the US Advanced Gas Reactor Fuel Development and Qualification Program. The experiment consisted of 72 right cylinder fuel compacts containing approximately 3 × 105 coated fuel particles with uranium oxide/uranium carbide (UCO) fuel kernels. The fuel was irradiated in the Advanced Test Reactor for a total of 620 effective full power days. Fuel burnup ranged from 11.3 to 19.6% fissions per initial metal atom and time-average, volume-average irradiation temperatures of the individual compacts ranged from 955 to 1136 °C. This paper focuses on keymore » results from the irradiation and post-irradiation examination, which revealed a robust fuel with excellent performance characteristics under the conditions tested and have significantly improved the understanding of UCO coated particle fuel irradiation behavior. The fuel exhibited zero TRISO coating failures (failure of all three dense coating layers) during irradiation and post-irradiation safety testing at temperatures up to 1700 °C. Advanced PIE methods have allowed particles with SiC coating failure that were discovered to be present in a very-low population to be isolated and meticulously examined, which has elucidated the specific causes of SiC failure in these specimens. The level of fission product release from the fuel during irradiation and post-irradiation safety testing has been studied in detail. Results indicated very low release of krypton and cesium through intact SiC and modest release of europium and strontium, while also confirming the potential for significant silver release through the coatings depending on irradiation conditions. Focused study of fission products within the coating layers of irradiated particles down to nanometer length scales has provided new insights into fission product transport through the coating layers and the role various fission products may have on coating integrity. The broader implications of these results and the application of lessons learned from AGR-1 to fuel fabrication and post-irradiation examination for subsequent fuel irradiation experiments as part of the US fuel program are also discussed.« less

Key results from irradiation and post-irradiation examination of AGR-1 UCO TRISO fuel

DOE PAGES

Demkowicz, Paul A.; Hunn, John D.; Petti, David A.; ...

2017-09-10

The AGR-1 irradiation experiment was performed as the first test of tristructural isotropic (TRISO) fuel in the US Advanced Gas Reactor Fuel Development and Qualification Program. The experiment consisted of 72 right cylinder fuel compacts containing approximately 3 × 105 coated fuel particles with uranium oxide/uranium carbide (UCO) fuel kernels. The fuel was irradiated in the Advanced Test Reactor for a total of 620 effective full power days. Fuel burnup ranged from 11.3 to 19.6% fissions per initial metal atom and time-average, volume-average irradiation temperatures of the individual compacts ranged from 955 to 1136 °C. This paper focuses on keymore » results from the irradiation and post-irradiation examination, which revealed a robust fuel with excellent performance characteristics under the conditions tested and have significantly improved the understanding of UCO coated particle fuel irradiation behavior. The fuel exhibited zero TRISO coating failures (failure of all three dense coating layers) during irradiation and post-irradiation safety testing at temperatures up to 1700 °C. Advanced PIE methods have allowed particles with SiC coating failure that were discovered to be present in a very-low population to be isolated and meticulously examined, which has elucidated the specific causes of SiC failure in these specimens. The level of fission product release from the fuel during irradiation and post-irradiation safety testing has been studied in detail. Results indicated very low release of krypton and cesium through intact SiC and modest release of europium and strontium, while also confirming the potential for significant silver release through the coatings depending on irradiation conditions. Focused study of fission products within the coating layers of irradiated particles down to nanometer length scales has provided new insights into fission product transport through the coating layers and the role various fission products may have on coating integrity. The broader implications of these results and the application of lessons learned from AGR-1 to fuel fabrication and post-irradiation examination for subsequent fuel irradiation experiments as part of the US fuel program are also discussed.« less

In-vitro bioactivity, biocorrosion and antibacterial activity of silicon integrated hydroxyapatite/chitosan composite coating on 316 L stainless steel implants.

PubMed

Sutha, S; Kavitha, K; Karunakaran, G; Rajendran, V

2013-10-01

A simple and effective ultrasonication method was applied for the preparation of 0, 0.4, 0.8, 1.0 and 1.6 wt% silicon substituted hydroxyapatite (HAp) (SH). The Ca/P ratio of the synthesised SH nanoparticles were in the range of 1.58-1.70. Morphological changes were noticed in HAp with respect to the amount of Si from 0 to 1.6 wt%. The morphology of the particles changed from spherical shape to rod-like morphology with respect to the amount of Si which was confirmed using transmission electron microscopy. X-ray diffraction studies confirm the formation of phase pure SH nanoparticles without any secondary phase. Chitosan (CTS) blended SH nanocomposites coating on surgical grade 316 L stainless steel (316 L SS) implant was made by spin coating technique. The surface of the coated implant was characterised using scanning electron microscopy which confirms the uniform coating without cracks and pores. The increased corrosion resistance of the 1.6 wt% of SH/CTS-coated SS implant in the simulated body fluid (SBF) indicates the long-term biostability of SH composite-coated ceramics in vitro than the 0 wt% SH/CTS. The testing of SH/CTS nanocomposites with gram-positive and gram-negative bacterial strains confirms that the antibacterial ability improves with the higher substitution of Si. In addition, formation of bone-like apatite layer on the SH/CTS-coated implant in SBF was studied through SEM analysis and it confirms the ability to increase the HAp formation on the surface of 1.0 wt% SH/CTS-coated 316 L SS implant. Copyright © 2013 Elsevier B.V. All rights reserved.

Effects of post-heat treatment on microstructure and properties of laser cladded composite coatings on titanium alloy substrate

NASA Astrophysics Data System (ADS)

Li, G. J.; Li, J.; Luo, X.

2015-01-01

The composite coatings were produced on the Ti6Al4V alloy substrate by laser cladding. Subsequently, the coatings were heated at 500 °C for 1 h and 2 h and then cooled in air. Effects of post-heat treatment on microstructure, microhardness and fracture toughness of the coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), optical microscopy (OM). Wear resistance of the coatings was evaluated under the dry sliding reciprocating friction condition at room temperature. The results indicated that the coatings mainly consist of a certain amount of coarse white equiaxed WC particles surrounded by the white-bright W2C, a great deal of fine dark spherical TiC particles and the matrix composed of the α(Ti), Ti2Ni and TiNi phases. Effects of the post-heat treatment on phase constituents and microstructure of the coatings were almost negligible due to the low temperature. However, the post-heat treatment could decrease the residual stress and increase fracture toughness of the coatings, and fracture toughness of the coatings was improved from 2.77 MPa m1/2 to 3.80 MPa m1/2 and 4.43 MPa m1/2 with the heat treatment for 1 h and 2 h, respectively. The mutual role would contribute to the reduction in cracking susceptibility. Accompanied with the increase in fracture toughness, microhardness of the coatings was reduced slightly. The dominant wear mechanism for all the coatings was abrasive wear, characterized by micro-cutting or micro-plowing. The heat treatment could significantly decrease the average friction coefficient and reduce the fluctuation of the friction coefficient with the change in sliding time. The appropriate heat treatment time (approximately 1 h) had a minimal effect on wear mass loss and volume loss. Moreover, the improvement in fracture toughness will also be beneficial to wear resistance of the coatings under the long service.

Biosynthesis of spherical and highly stable gold nanoparticles using Ferulago Angulata aqueous extract: dual role of extract

NASA Astrophysics Data System (ADS)

Alizadeh, A.; Parsafar, S.; Khodaei, M. M.

2017-03-01

A biocompatible method for synthesizing of highly disperses gold nanoparticles using Ferulago Angulata leaf extract has been developed. It has been shown that leaf extract acts as reducing and coating agent. Various spectroscopic and electron microscopic techniques were employed for the structural characterization of the prepared nanoparticles. The biosynthesized particles were identified as elemental gold with spherical morphology, narrow size distribution (ranged 9.2-17.5 nm) with high stability. Also, the effect of initial ratio of precursors, temperature and time of reaction on the size and morphology of the nanoparticles was studied in more detail. It was observed that varying these parameters provides an accessible remote control on the size and morphology of nanoparticles. The uniqueness of this procedure lies in its cleanliness using no extra surfactant, reducing agent or any capping agent.

Microwave limb sounder, graphite epoxy support structure

NASA Technical Reports Server (NTRS)

Pynchon, G.

1980-01-01

The manufacturing and processing procedures which were used to fabricate a precision graphite/epoxy support structure for a spherical microwave reflecting surface are described. The structure was made fromm GY-70/930 ultra high modulus graphite prepreg, laminated to achieve an isotropic in plane thermal expansion of less than + or - 0.1 PPM/F. The structure was hand assembled to match the interface of the reflective surface, which was an array of 18 flexure supported, aluminum, spherically contoured tiles. Structural adhesives were used in the final assembly to bond the elements into their final configuration. A eutectic metal coating was applied to the composite surface to reduce dimensional instabilities arising from changes in the composite epoxy moisture content due to environmental effects. Basic materials properties data are reported and the results of a finite element structural analysis are referenced.

Direct Observation on Spin-Coating Process of PS- b -P2VP Thin Films

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

Ogawa, Hiroki; Takenaka, Mikihito; Miyazaki, Tsukasa

We studied the structural development of symmetric poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) block copolymers during spin-coating using in situ grazing incidence small angle X-ray scattering (GISAXS) measurements. During the spin-coating process, after the formation of the micelles in dilute solution, the selective solvent induced two kinds of the morphological transition. Firstly, the disordered spherical micelles were transformed into a BCC lattice of spheres of which the (110) plane was oriented perpendicularly to the substrate surface. Secondly, further evaporation induced a transition from spheres on the BCC lattice into cylindrical structures. The orientation of the cylinders perpendicular to the substrate surface was induced bymore » solvent convection perpendicular to the substrate, which occurs during rapid solvent evaporation. After this transition, vitrification of PS and P2VP prevented any further transition from cylinders to the more thermodynamically stable lamellar structures, as are generally observed as the bulk equilibrium state.« less

Initial examination of fuel compacts and TRISO particles from the US AGR-2 irradiation test

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

Hunn, John D.; Baldwin, Charles A.; Montgomery, Fred C.

Post-irradiation examination was completed on two as-irradiated compacts from the US Advanced Gas Reactor Fuel Development and Qualification Program’s second irradiation test. These compacts were selected for examination because there were indications that they may have contained particles that released cesium through a failed or defective SiC layer. The coated particles were recovered from these compacts by electrolytic deconsolidation of the surrounding graphitic matrix in nitric acid. The leach-burn-leach (LBL) process was used to dissolve and analyze exposed metallic elements (actinides and fission products), and each particle was individually surveyed for relative cesium retention with the Irradiated Microsphere Gamma Analyzermore » (IMGA). Data from IMGA and LBL examinations provided information on fission product release during irradiation and whether any specific particles had below-average retention that could be related to coating layer defects or radiation-induced degradation. A few selected normal-retention particles and six with abnormally-low cesium inventory were analyzed using X-ray tomography to produce three-dimensional images of the internal coating structure. Four of the low-cesium particles had obviously damaged or degraded SiC, and X-ray imaging was able to guide subsequent grinding and polishing to expose the regions of interest for analysis by optical and electron microscopy. Additional particles from each compact were also sectioned and examined to study the overall radiation-induced microstructural changes in the kernel and coating layers.« less

Initial examination of fuel compacts and TRISO particles from the US AGR-2 irradiation test

DOE PAGES

Hunn, John D.; Baldwin, Charles A.; Montgomery, Fred C.; ...

2017-10-21

Post-irradiation examination was completed on two as-irradiated compacts from the US Advanced Gas Reactor Fuel Development and Qualification Program’s second irradiation test. These compacts were selected for examination because there were indications that they may have contained particles that released cesium through a failed or defective SiC layer. The coated particles were recovered from these compacts by electrolytic deconsolidation of the surrounding graphitic matrix in nitric acid. The leach-burn-leach (LBL) process was used to dissolve and analyze exposed metallic elements (actinides and fission products), and each particle was individually surveyed for relative cesium retention with the Irradiated Microsphere Gamma Analyzermore » (IMGA). Data from IMGA and LBL examinations provided information on fission product release during irradiation and whether any specific particles had below-average retention that could be related to coating layer defects or radiation-induced degradation. A few selected normal-retention particles and six with abnormally-low cesium inventory were analyzed using X-ray tomography to produce three-dimensional images of the internal coating structure. Four of the low-cesium particles had obviously damaged or degraded SiC, and X-ray imaging was able to guide subsequent grinding and polishing to expose the regions of interest for analysis by optical and electron microscopy. Additional particles from each compact were also sectioned and examined to study the overall radiation-induced microstructural changes in the kernel and coating layers.« less

Uranium extraction from TRISO-coated fuel particles using supercritical CO2 containing tri-n-butyl phosphate.

PubMed

Zhu, Liyang; Duan, Wuhua; Xu, Jingming; Zhu, Yongjun

2012-11-30

High-temperature gas-cooled reactors (HTGRs) are advanced nuclear systems that will receive heavy use in the future. It is important to develop spent nuclear fuel reprocessing technologies for HTGR. A new method for recovering uranium from tristructural-isotropic (TRISO-) coated fuel particles with supercritical CO(2) containing tri-n-butyl phosphate (TBP) as a complexing agent was investigated. TRISO-coated fuel particles from HTGR fuel elements were first crushed to expose UO(2) pellet fuel kernels. The crushed TRISO-coated fuel particles were then treated under O(2) stream at 750°C, resulting in a mixture of U(3)O(8) powder and SiC shells. The conversion of U(3)O(8) into solid uranyl nitrate by its reaction with liquid N(2)O(4) in the presence of a small amount of water was carried out. Complete conversion was achieved after 60 min of reaction at 80°C, whereas the SiC shells were not converted by N(2)O(4). Uranyl nitrate in the converted mixture was extracted with supercritical CO(2) containing TBP. The cumulative extraction efficiency was above 98% after 20 min of online extraction at 50°C and 25 MPa, whereas the SiC shells were not extracted by TBP. The results suggest an attractive strategy for reprocessing spent nuclear fuel from HTGR to minimize the generation of secondary radioactive waste. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of ternary Ni-TiO2-TiC composite coatings and their enhanced microhardness for metal finishing application

NASA Astrophysics Data System (ADS)

Kumaraguru, S.; Kumar, Gopika G.; Raghu, S.; Gnanamuthu, RM.

2018-07-01

Nickel (Ni) is extensively used for major engineering application. But nickel exhibits lower mechanical properties such as hardness and wear resistance than Ni-based composite materials. So, in this work, we significantly improve the mechanical properties of Ni by incorporating titanium dioxide (TiO2) and titanium carbide (TiC) particles. Ni-TiO2-TiC composite coatings are successfully prepared on mild steel specimens by means of electrodeposition technique. The prepared coatings are characterized by employing X-ray diffraction (XRD), energy dispersive X-ray fluorescence spectroscopy (EDXRF), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Vicker's hardness tester. The surface morphological analysis points out the growth of cauliflower morphology and pyramid-like structure decorated with spherical particles at room temperature. Likewise, hill-valley like structure has been formed in the electrolyte temperature of 75 °C. The upshot of electrolyte temperature and concentration of TiO2-TiC particles on the microhardness of the composite deposits is investigated. The microhardness value is superior when the higher quantity of TiO2-TiC particles encapsulated in the coatings.

Kernel abortion in maize : I. Carbohydrate concentration patterns and Acid invertase activity of maize kernels induced to abort in vitro.

PubMed

Hanft, J M; Jones, R J

1986-06-01

Kernels cultured in vitro were induced to abort by high temperature (35 degrees C) and by culturing six kernels/cob piece. Aborting kernels failed to enter a linear phase of dry mass accumulation and had a final mass that was less than 6% of nonaborting field-grown kernels. Kernels induced to abort by high temperature failed to synthesize starch in the endosperm and had elevated sucrose concentrations and low fructose and glucose concentrations in the pedicel during early growth compared to nonaborting kernels. Kernels induced to abort by high temperature also had much lower pedicel soluble acid invertase activities than did nonaborting kernels. These results suggest that high temperature during the lag phase of kernel growth may impair the process of sucrose unloading in the pedicel by indirectly inhibiting soluble acid invertase activity and prevent starch synthesis in the endosperm. Kernels induced to abort by culturing six kernels/cob piece had reduced pedicel fructose, glucose, and sucrose concentrations compared to kernels from field-grown ears. These aborting kernels also had a lower pedicel soluble acid invertase activity compared to nonaborting kernels from the same cob piece and from field-grown ears. The low invertase activity in pedicel tissue of the aborting kernels was probably caused by a lack of substrate (sucrose) for the invertase to cleave due to the intense competition for available assimilates. In contrast to kernels cultured at 35 degrees C, aborting kernels from cob pieces containing all six kernels accumulated starch in a linear fashion. These results indicate that kernels cultured six/cob piece abort because of an inadequate supply of sugar and are similar to apical kernels from field-grown ears that often abort prior to the onset of linear growth.

Microencapsulation and Electrostatic Processing Method

NASA Technical Reports Server (NTRS)

Morrison, Dennis R. (Inventor); Mosier, Benjamin (Inventor)

2000-01-01

Methods are provided for forming spherical multilamellar microcapsules having alternating hydrophilic and hydrophobic liquid layers, surrounded by flexible, semi-permeable hydrophobic or hydrophilic outer membranes which can be tailored specifically to control the diffusion rate. The methods of the invention rely on low shear mixing and liquid-liquid diffusion process and are particularly well suited for forming microcapsules containing both hydrophilic and hydrophobic drugs. These methods can be carried out in the absence of gravity and do not rely on density-driven phase separation, mechanical mixing or solvent evaporation phases. The methods include the process of forming, washing and filtering microcapsules. In addition, the methods contemplate coating microcapsules with ancillary coatings using an electrostatic field and free fluid electrophoresis of the microcapsules. The microcapsules produced by such methods are particularly useful in the delivery of pharmaceutical compositions.

Facile synthesis of biocompatible gold nanoparticles with organosilicone-coated surface properties

NASA Astrophysics Data System (ADS)

Xia, Lijin; Yi, Sijia; Lenaghan, Scott C.; Zhang, Mingjun

2012-07-01

In this study, a simple method for one-step synthesis of gold nanoparticles has been developed using an organosilicone surfactant, Silwet L-77, as both a reducing and capping agent. Synthesis of gold nanoparticles using this method is rapid and can be conducted conveniently at ambient temperature. Further refinement of the method, through the addition of sodium hydroxide and/or silver nitrate, allowed fine control over the size of spherical nanoparticles produced. Coated on the surface with organosilicone, the as-prepared gold nanoparticles were biocompatible and stable over the pH range from 5 to 12, and have been proven effective at transportation into MC3T3 osteoblast cells. The proposed method is simple, fast, and can produce size-controlled gold nanoparticles with unique surface properties for biomedical applications.

Evaluation of the effectiveness factor along immobilized enzyme fixed-bed reactors: design of a reactor with naringinase covalently immobilized into glycophase-coated porous glass

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

Manjon, A.; Iborra, J.L.; Gomez, J.L.

A design equation is presented for packed-bed reactors containing immobilized enzymes in spherical porous particles with internal diffusion effects and obeying reversible one-intermediate Michaelis-Menten kinetics. The equation is also able to explain irreversible and competitive product inhibition kinetics. It allows the axial substrate profiles to be calculated and the dependence of the effectiveness factor along the reactor length to be continuously evaluated. The design equation was applied to explain the behavior of naringinase immobilized in Glycophase-coated porous glass operating in a packed-bed reactor and hydrolyzing both p-nitrophenyl-alpha-L-rhamnoside and naringin. The theoretically predicted results were found to fit well with experimentallymore » measured values. (Refs. 28).« less

Magnetic properties of carbon-coated, ferromagnetic nanoparticles produced by a carbon-arc method

NASA Astrophysics Data System (ADS)

Brunsman, E. M.; Sutton, R.; Bortz, E.; Kirkpatrick, S.; Midelfort, K.; Williams, J.; Smith, P.; McHenry, M. E.; Majetich, S. A.; Artman, J. O.; De Graef, M.; Staley, S. W.

1994-05-01

The Krätschmer-Huffman carbon-arc method of preparing fullerenes has been used to generate carbon-coated transition metal (TM) and TM-carbide nanocrystallites. The magnetic nanocrystallites were extracted from the soot with a magnetic gradient field technique. For TM=Co the majority of nanocrystals exist as nominally spherical particles, 0.5-5 nm in radius. Hysteretic and temperature-dependent magnetic response, in randomly and magnetically aligned powder samples frozen in epoxy, correspond to fine particle magnetism associated with monodomain TM particles. The magnetization exhibits a unique functional dependence on H/T, and hysteresis below a blocking temperature TB. Below TB, the temperature dependence of the coercivity can be expressed as Hc=Hc0[1-(T/TB)1/2], where Hc0 is the 0 K coercivity.

Observation of nitrate coatings on atmospheric mineral dust particles

NASA Astrophysics Data System (ADS)

Li, W. J.; Shao, L. Y.

2009-03-01

Nitrate compounds have received much attention because of their ability to alter the hygroscopic properties and cloud condensation nuclei (CCN) activity of mineral dust particles in the atmosphere. However, very little is known about specific characteristics of ambient nitrate-coated mineral particles on an individual particle scale. In this study, sample collection was conducted during brown haze and dust episodes between 24 May and 21 June 2007 in Beijing, northern China. Sizes, morphologies, and compositions of 332 mineral dust particles together with their coatings were analyzed using transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX) microanalyses. Structures of some mineral particles were verified using selected-area electron diffraction (SAED). TEM observation indicates that approximately 90% of the collected mineral particles are covered by visible coatings in haze samples whereas only 5% are coated in the dust sample. 92% of the analyzed mineral particles are covered with Ca-, Mg-, and Na-rich coatings, and 8% are associated with K- and S-rich coatings. The majority of coatings contain Ca, Mg, O, and N with minor amounts of S and Cl, suggesting that they are possibly nitrates mixed with small amounts of sulfates and chlorides. These nitrate coatings are strongly correlated with the presence of alkaline mineral components (e.g., calcite and dolomite). CaSO4 particles with diameters from 10 to 500 nm were also detected in the coatings including Ca(NO3)2 and Mg(NO3)2. Our results indicate that mineral particles in brown haze episodes were involved in atmospheric heterogeneous reactions with two or more acidic gases (e.g., SO2, NO2, HCl, and HNO3). Mineral particles that acquire hygroscopic nitrate coatings tend to be more spherical and larger, enhancing their light scattering and CCN activity, both of which have cooling effects on the climate.

7 CFR 810.602 - Definition of other terms.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Damaged kernels. Kernels and pieces of flaxseed kernels that are badly ground-damaged, badly weather... instructions. Also, underdeveloped, shriveled, and small pieces of flaxseed kernels removed in properly... recleaning. (c) Heat-damaged kernels. Kernels and pieces of flaxseed kernels that are materially discolored...

Enhanced direct-drive implosions with thin high-Z ablation layers.

PubMed

Mostovych, Andrew N; Colombant, Denis G; Karasik, Max; Knauer, James P; Schmitt, Andrew J; Weaver, James L

2008-02-22

New direct-drive spherical implosion experiments with deuterium filled plastic shells have demonstrated significant and absolute (2x) improvements in neutron yield when the shells are coated with a very thin layer ( approximately 200-400 A) of high-Z material such as palladium. This improvement is interpreted as resulting from increased stability of the imploding shell. These results provide for a possible path to control laser imprint and stability in laser-fusion-energy target designs.

Spin coating and plasma process for 2.5D and hybrid 3D micro-resonators on multilayer polymers

NASA Astrophysics Data System (ADS)

Bêche, B.; Gaviot, E.; Godet, C.; Zebda, A.; Potel, A.; Barbe, J.; Camberlein, L.; Vié, V.; Panizza, P.; Loas, G.; Hamel, C.; Zyss, J.; Huby, N.

2009-05-01

We have designed and realized three integrated photonic families of micro-resonators (MR) on multilayer organic materials. Such so-called 2.5D-MR and 3D-MR structures show off radius values ranging from 40 to 200μm. Both first and second families are especially designed on organic multilayer materials and shaped as ring- and disk-MR organics structures arranged upon (and coupled with) a pair of SU8-organic waveguides. The third family is related to hybrid 3D-MR structures composed of spherical glass-MR coupled to organic waveguides by a Langmuir-Blodgett lipid film about three nanometers in thickness. At first, polymer spin coating, surface plasma treatment and selective UV-lithography processes have been developed to realize 2.5D photonic micro-resonators. Secondly, we have designed and characterized photonic-quadripoles made of 3D-glass-MR arranged upon a pair of SU8 waveguides. Such structures are defined by a 4-ports or 4-waveguides coupled by the spherical glass-MR. We have achieved an evanescent photonic coupling between the 3D-MR and the 4-ports structure. Spectral resonances have been measured for 4-whispering gallery-modes (WGM) into such 3D-structures respectively characterized by a 0.97 nm free spectral range (FSR) and a high quality Q-factor up to 4.104.

Kernel Abortion in Maize 1

PubMed Central

Hanft, Jonathan M.; Jones, Robert J.

1986-01-01

Kernels cultured in vitro were induced to abort by high temperature (35°C) and by culturing six kernels/cob piece. Aborting kernels failed to enter a linear phase of dry mass accumulation and had a final mass that was less than 6% of nonaborting field-grown kernels. Kernels induced to abort by high temperature failed to synthesize starch in the endosperm and had elevated sucrose concentrations and low fructose and glucose concentrations in the pedicel during early growth compared to nonaborting kernels. Kernels induced to abort by high temperature also had much lower pedicel soluble acid invertase activities than did nonaborting kernels. These results suggest that high temperature during the lag phase of kernel growth may impair the process of sucrose unloading in the pedicel by indirectly inhibiting soluble acid invertase activity and prevent starch synthesis in the endosperm. Kernels induced to abort by culturing six kernels/cob piece had reduced pedicel fructose, glucose, and sucrose concentrations compared to kernels from field-grown ears. These aborting kernels also had a lower pedicel soluble acid invertase activity compared to nonaborting kernels from the same cob piece and from field-grown ears. The low invertase activity in pedicel tissue of the aborting kernels was probably caused by a lack of substrate (sucrose) for the invertase to cleave due to the intense competition for available assimilates. In contrast to kernels cultured at 35°C, aborting kernels from cob pieces containing all six kernels accumulated starch in a linear fashion. These results indicate that kernels cultured six/cob piece abort because of an inadequate supply of sugar and are similar to apical kernels from field-grown ears that often abort prior to the onset of linear growth. PMID:16664846

Out-of-Sample Extensions for Non-Parametric Kernel Methods.

PubMed

Pan, Binbin; Chen, Wen-Sheng; Chen, Bo; Xu, Chen; Lai, Jianhuang

2017-02-01

Choosing suitable kernels plays an important role in the performance of kernel methods. Recently, a number of studies were devoted to developing nonparametric kernels. Without assuming any parametric form of the target kernel, nonparametric kernel learning offers a flexible scheme to utilize the information of the data, which may potentially characterize the data similarity better. The kernel methods using nonparametric kernels are referred to as nonparametric kernel methods. However, many nonparametric kernel methods are restricted to transductive learning, where the prediction function is defined only over the data points given beforehand. They have no straightforward extension for the out-of-sample data points, and thus cannot be applied to inductive learning. In this paper, we show how to make the nonparametric kernel methods applicable to inductive learning. The key problem of out-of-sample extension is how to extend the nonparametric kernel matrix to the corresponding kernel function. A regression approach in the hyper reproducing kernel Hilbert space is proposed to solve this problem. Empirical results indicate that the out-of-sample performance is comparable to the in-sample performance in most cases. Experiments on face recognition demonstrate the superiority of our nonparametric kernel method over the state-of-the-art parametric kernel methods.

7 CFR 810.1202 - Definition of other terms.

Code of Federal Regulations, 2010 CFR

2010-01-01

... kernels. Kernels, pieces of rye kernels, and other grains that are badly ground-damaged, badly weather.... Also, underdeveloped, shriveled, and small pieces of rye kernels removed in properly separating the...-damaged kernels. Kernels, pieces of rye kernels, and other grains that are materially discolored and...

The Genetic Basis of Natural Variation in Kernel Size and Related Traits Using a Four-Way Cross Population in Maize.

PubMed

Chen, Jiafa; Zhang, Luyan; Liu, Songtao; Li, Zhimin; Huang, Rongrong; Li, Yongming; Cheng, Hongliang; Li, Xiantang; Zhou, Bo; Wu, Suowei; Chen, Wei; Wu, Jianyu; Ding, Junqiang

2016-01-01

Kernel size is an important component of grain yield in maize breeding programs. To extend the understanding on the genetic basis of kernel size traits (i.e., kernel length, kernel width and kernel thickness), we developed a set of four-way cross mapping population derived from four maize inbred lines with varied kernel sizes. In the present study, we investigated the genetic basis of natural variation in seed size and other components of maize yield (e.g., hundred kernel weight, number of rows per ear, number of kernels per row). In total, ten QTL affecting kernel size were identified, three of which (two for kernel length and one for kernel width) had stable expression in other components of maize yield. The possible genetic mechanism behind the trade-off of kernel size and yield components was discussed.

The Genetic Basis of Natural Variation in Kernel Size and Related Traits Using a Four-Way Cross Population in Maize

PubMed Central

Liu, Songtao; Li, Zhimin; Huang, Rongrong; Li, Yongming; Cheng, Hongliang; Li, Xiantang; Zhou, Bo; Wu, Suowei; Chen, Wei; Wu, Jianyu; Ding, Junqiang

2016-01-01

Kernel size is an important component of grain yield in maize breeding programs. To extend the understanding on the genetic basis of kernel size traits (i.e., kernel length, kernel width and kernel thickness), we developed a set of four-way cross mapping population derived from four maize inbred lines with varied kernel sizes. In the present study, we investigated the genetic basis of natural variation in seed size and other components of maize yield (e.g., hundred kernel weight, number of rows per ear, number of kernels per row). In total, ten QTL affecting kernel size were identified, three of which (two for kernel length and one for kernel width) had stable expression in other components of maize yield. The possible genetic mechanism behind the trade-off of kernel size and yield components was discussed. PMID:27070143

Fabrication and in vitro release behavior of a novel antibacterial coating containing halogenated furanone-loaded poly(L-lactic acid) nanoparticles on microarc-oxidized titanium

PubMed Central

Cheng, Yicheng; Wu, Jiang; Gao, Bo; Zhao, Xianghui; Yao, Junyan; Mei, Shenglin; Zhang, Liang; Ren, Huifang

2012-01-01

Background Dental implants have become increasingly common for the management of missing teeth. However, peri-implant infection remains a problem, is usually difficult to treat, and may lead eventually to dental implant failure. The aim of this study was to fabricate a novel antibacterial coating containing a halogenated furanone compound, ie, (Z-)-4-bromo-5-(bromomethylene)-2(5H)-furanone (BBF)-loaded poly(L-lactic acid) (PLLA) nanoparticles on microarc-oxidized titanium and to evaluate its release behavior in vitro. Methods BBF-loaded PLLA nanoparticles were prepared using the emulsion solvent-evaporation method, and the antibacterial coating was fabricated by cross-linking BBF-loaded PLLA nanoparticles with gelatin on microarc-oxidized titanium. Results The BBF-loaded PLLA nanoparticles had a small particle size (408 ± 14 nm), a low polydispersity index (0.140 ± 0.008), a high encapsulation efficiency (72.44% ± 1.27%), and a fine spherical shape with a smooth surface. The morphology of the fabricated antibacterial coating showed that the BBF-loaded PLLA nanoparticles were well distributed in the pores of the microarc oxidation coating, and were cross-linked with each other and the wall pores by gelatin. The release study indicated that the antibacterial coating could achieve sustained release of BBF for 60 days, with a slight initial burst release during the first 4 hours. Conclusion The novel antibacterial coating fabricated in this study is a potentially promising method for prevention of early peri-implant infection. PMID:23152682

Long-acting inhalable chitosan-coated poly(lactic-co-glycolic acid) nanoparticles containing hydrophobically modified exendin-4 for treating type 2 diabetes

PubMed Central

Lee, Changkyu; Choi, Ji Su; Kim, Insoo; Oh, Kyung Taek; Lee, Eun Seong; Park, Eun-Seok; Lee, Kang Choon; Youn, Yu Seok

2013-01-01

Inhalable glycol chitosan-coated poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing palmitic acid-modified exendin-4 (Pal-Ex4) (chitosan Pal-Ex4 PLGA NPs) were prepared and characterized. The surface morphology, particle size, and zeta potential of chitosan Pal-Ex4 PLGA NPs were investigated, and the adsorption and cytotoxicity of chitosan Pal-Ex4 PLGA NPs were evaluated in human lung epithelial cells (A549). Finally, the lung deposition characteristics and hypoglycemia caused by chitosan Pal-Ex4 PLGA NPs were evaluated after pulmonary administration in imprinting control region (ICR) and type 2 diabetic db/db mice. Results showed that chitosan Pal-Ex4 PLGA NPs were spherical, compact and had a diameter of ~700 nm and a positive surface charge of +28.5 mV Chitosan-coated PLGA NPs were adsorbed onto A549 cells much more so than non-coated PLGA NPs. Pal-Ex4 release from chitosan-coated PLGA NPs was delayed by as much as 1.5 days as compared with chitosan-coated Ex4 PLGA NPs. In addition, chitosan-coated PLGA NPs remained in the lungs for ~72 hours after pulmonary administration, whereas most non-coated PLGA NPs were lost at 8 hours after administration. Furthermore, the hypoglycemic efficacy of inhaled chitosan Pal-Ex4 PLGA NPs was 3.1-fold greater than that of chitosan Ex4 PLGA NPs in db/db mice. The authors believe chitosan Pal-Ex4 PLGA NPs have considerable potential as a long-acting inhalation delivery system for the treatment of type 2 diabetes. PMID:23976850

Analysis and Development of A Robust Fuel for Gas-Cooled Fast Reactors

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

Knight, Travis W.

2010-01-31

The focus of this effort was on the development of an advanced fuel for gas-cooled fast reactor (GFR) applications. This composite design is based on carbide fuel kernels dispersed in a ZrC matrix. The choice of ZrC is based on its high temperature properties and good thermal conductivity and improved retention of fission products to temperatures beyond that of traditional SiC based coated particle fuels. A key component of this study was the development and understanding of advanced fabrication techniques for GFR fuels that have potential to reduce minor actinide (MA) losses during fabrication owing to their higher vapor pressuresmore » and greater volatility. The major accomplishments of this work were the study of combustion synthesis methods for fabrication of the ZrC matrix, fabrication of high density UC electrodes for use in the rotating electrode process, production of UC particles by rotating electrode method, integration of UC kernels in the ZrC matrix, and the full characterization of each component. Major accomplishments in the near-term have been the greater characterization of the UC kernels produced by the rotating electrode method and their condition following the integration in the composite (ZrC matrix) following the short time but high temperature combustion synthesis process. This work has generated four journal publications, one conference proceeding paper, and one additional journal paper submitted for publication (under review). The greater significance of the work can be understood in that it achieved an objective of the DOE Generation IV (GenIV) roadmap for GFR Fuel—namely the demonstration of a composite carbide fuel with 30% volume fuel. This near-term accomplishment is even more significant given the expected or possible time frame for implementation of the GFR in the years 2030 -2050 or beyond.« less

Agarose coated spherical micro resonator for humidity measurements.

PubMed

Mallik, Arun Kumar; Liu, Dejun; Kavungal, Vishnu; Wu, Qiang; Farrell, Gerald; Semenova, Yuliya

2016-09-19

A new type of fiber optic relative humidity (RH) sensor based on an agarose coated silica microsphere resonator is proposed and experimentally demonstrated. Whispering gallery modes (WGMs) in the micro resonator are excited by evanescent coupling using a tapered fiber with ~3.3 µm waist diameter. A change in the relative humidity of the surrounding the resonator air induces changes in the refractive index (RI) and thickness of the Agarose coating layer. These changes in turn lead to a spectral shift of the WGM resonances, which can be related to the RH value after a suitable calibration. Studies of the repeatability, long-term stability, measurement accuracy and temperature dependence of the proposed sensor are carried out. The RH sensitivity of the proposed sensor depends on the concentration of the agarose gel which determines the initial thickness of the deposited coating layer. Studies of the micro- resonators with coating layers fabricated from gels with three different Agarose concentrations of 0.5%, 1.125% and 2.25 wt./vol.% showed that an increase in the initial thickness of the coating material results in an increase in sensitivity but also leads to a decrease of quality factor (Q) of the micro resonator. The highest sensitivity achieved in our experiments was 518 pm/%RH in the RH range from 30% to 70%. The proposed sensor offers the advantages of a very compact form factor, low hysteresis, good repeatability, and low cross sensitivity to temperature.

KEY RESULTS FROM IRRADIATION AND POST-IRRADIATION EXAMINATION OF AGR-1 UCO TRISO FUEL

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

Demkowicz, Paul A.; Hunn, John D.; Petti, David A.

The AGR-1 irradiation experiment was performed as the first test of tristructural isotropic (TRISO) fuel in the US Advanced Gas Reactor Fuel Development and Qualification Program. The experiment consisted of 72 right cylinder fuel compacts containing approximately 3×105 coated fuel particles with uranium oxide/uranium carbide (UCO) fuel kernels. The fuel was irradiated in the Advanced Test Reactor for a total of 620 effective full power days. Fuel burnup ranged from 11.3 to 19.6% fissions per initial metal atom and time average, volume average irradiation temperatures of the individual compacts ranged from 955 to 1136°C. This paper focuses on key resultsmore » from the irradiation and post-irradiation examination, which revealed a robust fuel with excellent performance characteristics under the conditions tested and have significantly improved the understanding of UCO coated particle fuel irradiation behavior within the US program. The fuel exhibited a very low incidence of TRISO coating failure during irradiation and post-irradiation safety testing at temperatures up to 1800°C. Advanced PIE methods have allowed particles with SiC coating failure to be isolated and meticulously examined, which has elucidated the specific causes of SiC failure in these specimens. The level of fission product release from the fuel during irradiation and post-irradiation safety testing has been studied in detail. Results indicated very low release of krypton and cesium through intact SiC and modest release of europium and strontium, while also confirming the potential for significant silver release through the coatings depending on irradiation conditions. Focused study of fission products within the coating layers of irradiated particles down to nanometer length scales has provided new insights into fission product transport through the coating layers and the role various fission products may have on coating integrity. The broader implications of these results and the application of lessons learned from AGR-1 to fuel fabrication and post-irradiation examination for subsequent fuel irradiation experiments as part of the US fuel program is also discussed.« less

SPOUTED BED DESIGN CONSIDERATIONS FOR COATED NUCLEAR FUEL PARTICLES

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

Marshall, Douglas W.

High Temperature Gas Cooled Reactors (HTGRs) are fueled with tristructural isotropic (TRISO) coated nuclear fuel particles embedded in a carbon-graphite fuel body. TRISO coatings consist of four layers of pyrolytic carbon and silicon carbide that are deposited on uranium ceramic fuel kernels (350µm – 500µm diameters) in a concatenated series of batch depositions. Each layer has dedicated functions such that the finished fuel particle has its own integral containment to minimize and control the release of fission products into the fuel body and reactor core. The TRISO coatings are the primary containment structure in the HTGR reactor and must havemore » very high uniformity and integrity. To ensure high quality TRISO coatings, the four layers are deposited by chemical vapor deposition (CVD) using high purity precursors and are applied in a concatenated succession of batch operations before the finished product is unloaded from the coating furnace. These depositions take place at temperatures ranging from 1230°C to 1550°C and use three different gas compositions, while the fuel particle diameters double, their density drops from 11.1 g/cm3 to 3.0 g/cm3, and the bed volume increases more than 8-fold. All this is accomplished without the aid of sight ports or internal instrumentation that could cause chemical contamination within the layers or mechanical damage to thin layers in the early stages of each layer deposition. The converging section of the furnace retort was specifically designed to prevent bed stagnation that would lead to unacceptably high defect fractions and facilitate bed circulation to avoid large variability in coating layer dimensions and properties. The gas injection nozzle was designed to protect precursor gases from becoming overheated prior to injection, to induce bed spouting and preclude bed stagnation in the bottom of the retort. Furthermore, the retort and injection nozzle designs minimize buildup of pyrocarbon and silicon carbide on the retort wall and manage nozzle orifice accretions. The equipment and operating methods have yielded very good reproducibility in the TRISO coated particles batches.« less

7 CFR 810.802 - Definition of other terms.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Damaged kernels. Kernels and pieces of grain kernels for which standards have been established under the.... (d) Heat-damaged kernels. Kernels and pieces of grain kernels for which standards have been...

Independent and collective roles of surface structures at different length scales on pool boiling heat transfer

PubMed Central

Li, Calvin H.; Rioux, Russell P.

2016-01-01

Spherical Cu nanocavity surfaces are synthesized to examine the individual role of contact angles in connecting lateral Rayleigh-Taylor wavelength to vertical Kevin-Helmholtz wavelength on hydrodynamic instability for the onset of pool boiling Critical Heat Flux (CHF). Solid and porous Cu pillar surfaces are sintered to investigate the individual role of pillar structure pitch at millimeter scale, named as module wavelength, on hydrodynamic instability at CHF. Last, spherical Cu nanocavities are coated on the porous Cu pillars to create a multiscale Cu structure, which is studied to examine the collective role and relative significance of contact angles and module wavelength on hydrodynamic instability at CHF, and the results indicate that module wavelength plays the dominant role on hydrodynamic instability at CHF when the height of surface structures is equal or above ¼ Kelvin-Helmholtz wavelength. Pool boiling Heat Transfer Coefficient (HTC) enhancements on spherical Cu nanocavity surfaces, solid and porous Cu pillar surfaces, and the integrated multiscale structure have been investigated, too. The experimental results reveal that the nanostructures and porous pillar structures can be combined together to achieve even higher enhancement of HTC than that of individual structures. PMID:27841322

Tearing of thin spherical shells adhered to equally curved rigid substrates

NASA Astrophysics Data System (ADS)

McMahan, Connor; Lee, Anna; Marthelot, Joel; Reis, Pedro

Lasik (Laser-Assisted in Situ Keratomileusis) eye surgery involves the tearing of the corneal epithelium to remodel the corneal stroma for corrections such as myopia, hyperopia and astigmatism. One issue with this procedure is that during the tearing of the corneal epithelium, if the two propagating cracks coalesce, a flap detaches which could cause significant complications in the recovery of the patient. We seek to gain a predictive physical understanding of this process by performing precision desktop experiments on an analogue model system. First, thin spherical shells of nearly uniform thickness are fabricated by the coating of hemispherical molds with a polymer solution, which upon curing yields an elastic and brittle structure. We then create two notches near the equator of the shell and tear a flap by pulling tangentially to the spherical substrate, towards its pole. The resulting fracture paths are characterized by high-resolution 3D digital scanning. Our primary focus is on establishing how the positive Gaussian curvature of the system affects the path of the crack tip. Our results are directly contrasted against previous studies on systems with zero Gaussian curvature, where films were torn from planar and cylindrical substrates.

7 CFR 981.408 - Inedible kernel.

Code of Federal Regulations, 2014 CFR

2014-01-01

... kernel is modified to mean a kernel, piece, or particle of almond kernel with any defect scored as... purposes of determining inedible kernels, pieces, or particles of almond kernels. [59 FR 39419, Aug. 3...

7 CFR 981.408 - Inedible kernel.

Code of Federal Regulations, 2011 CFR

2011-01-01

... kernel is modified to mean a kernel, piece, or particle of almond kernel with any defect scored as... purposes of determining inedible kernels, pieces, or particles of almond kernels. [59 FR 39419, Aug. 3...

7 CFR 981.408 - Inedible kernel.

Code of Federal Regulations, 2012 CFR

2012-01-01

... kernel is modified to mean a kernel, piece, or particle of almond kernel with any defect scored as... purposes of determining inedible kernels, pieces, or particles of almond kernels. [59 FR 39419, Aug. 3...

7 CFR 981.408 - Inedible kernel.

Code of Federal Regulations, 2013 CFR

2013-01-01

... kernel is modified to mean a kernel, piece, or particle of almond kernel with any defect scored as... purposes of determining inedible kernels, pieces, or particles of almond kernels. [59 FR 39419, Aug. 3...

Highly sensitive C-reactive protein (CRP) assay using metal-enhanced fluorescence (MEF)

NASA Astrophysics Data System (ADS)

Zhang, Yi; Keegan, Gemma L.; Stranik, Ondrej; Brennan-Fournet, Margaret E.; McDonagh, Colette

2015-07-01

Fluorescence has been extensively employed in the area of diagnostic immunoassays. A significant enhancement of fluorescence can be achieved when noble metal nanoparticles are placed in close proximity to fluorophores. This effect, referred to as metal-enhanced fluorescence (MEF), has the potential to produce immunoassays with a high sensitivity and a low limit of detection (LOD). In this study, we investigate the fluorescence enhancement effect of two different nanoparticle systems, large spherical silver nanoparticles (AgNPs) and gold edge-coated triangular silver nanoplates, and both systems were evaluated for MEF. The extinction properties and electric field enhancement of both systems were modeled, and the optimum system, spherical AgNPs, was used in a sandwich immunoassay for human C-reactive protein with a red fluorescent dye label. A significant enhancement in the fluorescence was observed, which corresponded to an LOD improvement of 19-fold compared to a control assay without AgNPs.

SHI irradiation effect on pure and Mn doped ZnO thin films

NASA Astrophysics Data System (ADS)

Khawal, H. A.; Raskar, N. D.; Dole, B. N.

2017-05-01

Investigated the structural, surface, electrical and modifications induced by Swift Heavy Ions (SHI) irradiation on pure and Mn substituted ZnO thin films were observed. Thin films of Zn1-xMnxO (x = 0.00, 0.04) were synthesized using the dip coating technique. All thin films irradiated by Li3+ swift heavy ions with fluence 5 × 1013 ions/cm2. The XRD peak reveals that all the samples exhibit wurtzite structures. Surface morphology of samples was investigated by SEM, it was observed that pristine samples of ZnO thin film shows spherical shape but for 4 % Mn substituted ZnO thin film with 5 × 1013 ions/cm2 fluence, it reveals that big grain spherical morphology like structure respectively. I-V characteristics were recorded in the voltage range -5 to 5 V. All curves were passed through origin and nearly linear exhibit ohmic in nature for the films.

Spherically-clustered porous Au-Ag alloy nanoparticle prepared by partial inhibition of galvanic replacement and its application for efficient multimodal therapy.

PubMed

Jang, Hongje; Min, Dal-Hee

2015-03-24

The polyvinylpyrrolidone (PVP)-coated spherically clustered porous gold-silver alloy nanoparticle (PVP-SPAN) was prepared by low temperature mediated, partially inhibited galvanic replacement reaction followed by silver etching process. The prepared porous nanostructures exhibited excellent photothermal conversion efficiency under irradiation of near-infrared light (NIR) and allowed a high payload of both doxorubicin (Dox) and thiolated dye-labeled oligonucleotide, DNAzyme (FDz). Especially, PVP-SPAN provided 10 times higher loading capacity for oligonucleotide than conventional hollow nanoshells due to increased pore diameter and surface-to-volume ratio. We demonstrated highly efficient chemo-thermo-gene multitherapy based on codelivery of Dox and FDz with NIR-mediated photothermal therapeutic effect using a model system of hepatitis C virus infected human liver cells (Huh7 human hepatocarcinoma cell line containing hepatitis C virus NS3 gene replicon) compared to conventional hollow nanoshells.

Computational study of the effect of gradient magnetic field in navigation of spherical particles

NASA Astrophysics Data System (ADS)

Karvelas, E. G.; Lampropoulos, N. K.; Papadimitriou, D. I.; Karakasidis, T. E.; Sarris, I. E.

2017-11-01

The use of spherical magnetic nanoparticles that are coated with drugs and can be navigated in arteries to attack tumors is proposed as an alternative to chemotherapy. Navigation of particles is due to magnetic field gradients that may be produced in an MRI device. In the present work, a computational study for the evaluation of the magnitude of the gradient magnetic field for particles navigation in Y bifurcations is presented. For this purpose, the presented method solves for the fluid flow and includes all the important forces that act on the particles in their discrete motion. The method is based on an iteration algorithm that adjusts the gradient magnetic field to minimize the particles’ deviation from a desired trajectory. Using the above mentioned method, the appropriate range of the gradient magnetic field for optimum navigation of nanoparticles’s aggregation is found.

Critical illumination condenser for x-ray lithography

DOEpatents

Cohen, S.J.; Seppala, L.G.

1998-04-07

A critical illumination condenser system is disclosed, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 {micro}m source and requires a magnification of 26. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth. 6 figs.

Critical illumination condenser for x-ray lithography

DOEpatents

Cohen, Simon J.; Seppala, Lynn G.

1998-01-01

A critical illumination condenser system, particularly adapted for use in extreme ultraviolet (EUV) projection lithography based on a ring field imaging system and a laser produced plasma source. The system uses three spherical mirrors and is capable of illuminating the extent of the mask plane by scanning either the primary mirror or the laser plasma source. The angles of radiation incident upon each mirror of the critical illumination condenser vary by less than eight (8) degrees. For example, the imaging system in which the critical illumination condenser is utilized has a 200 .mu.m source and requires a magnification of 26.times.. The three spherical mirror system constitutes a two mirror inverse Cassegrain, or Schwarzschild configuration, with a 25% area obstruction (50% linear obstruction). The third mirror provides the final pupil and image relay. The mirrors include a multilayer reflective coating which is reflective over a narrow bandwidth.

A Novel Extreme Learning Machine Classification Model for e-Nose Application Based on the Multiple Kernel Approach.

PubMed

Jian, Yulin; Huang, Daoyu; Yan, Jia; Lu, Kun; Huang, Ying; Wen, Tailai; Zeng, Tanyue; Zhong, Shijie; Xie, Qilong

2017-06-19

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme learning machine (MK-ELM) algorithms, the combination coefficients of base kernels are regarded as external parameters of single-hidden layer feedforward neural networks (SLFNs). The combination coefficients of base kernels, the model parameters of each base kernel, and the regularization parameter are optimized by QPSO simultaneously before implementing the kernel extreme learning machine (KELM) with the composite kernel function. Four types of common single kernel functions (Gaussian kernel, polynomial kernel, sigmoid kernel, and wavelet kernel) are utilized to constitute different composite kernel functions. Moreover, the method is also compared with other existing classification methods: extreme learning machine (ELM), kernel extreme learning machine (KELM), k-nearest neighbors (KNN), support vector machine (SVM), multi-layer perceptron (MLP), radical basis function neural network (RBFNN), and probabilistic neural network (PNN). The results have demonstrated that the proposed QWMK-ELM outperforms the aforementioned methods, not only in precision, but also in efficiency for gas classification.

Consistent Pl Analysis of Aqueous Uranium-235 Critical Assemblies

NASA Technical Reports Server (NTRS)

Fieno, Daniel

1961-01-01

The lethargy-dependent equations of the consistent Pl approximation to the Boltzmann transport equation for slowing down neutrons have been used as the basis of an IBM 704 computer program. Some of the effects included are (1) linearly anisotropic center of mass elastic scattering, (2) heavy element inelastic scattering based on the evaporation model of the nucleus, and (3) optional variation of the buckling with lethargy. The microscopic cross-section data developed for this program covered 473 lethargy points from lethargy u = 0 (10 Mev) to u = 19.8 (0.025 ev). The value of the fission neutron age in water calculated here is 26.5 square centimeters; this value is to be compared with the recent experimental value given as 27.86 square centimeters. The Fourier transform of the slowing-down kernel for water to indium resonance energy calculated here compared well with the Fourier transform of the kernel for water as measured by Hill, Roberts, and Fitch. This method of calculation has been applied to uranyl fluoride - water solution critical assemblies. Theoretical results established for both unreflected and fully reflected critical assemblies have been compared with available experimental data. The theoretical buckling curve derived as a function of the hydrogen to uranium-235 atom concentration for an energy-independent extrapolation distance was successful in predicting the critical heights of various unreflected cylindrical assemblies. The critical dimensions of fully water-reflected cylindrical assemblies were reasonably well predicted using the theoretical buckling curve and reflector savings for equivalent spherical assemblies.

Classification With Truncated Distance Kernel.

PubMed

Huang, Xiaolin; Suykens, Johan A K; Wang, Shuning; Hornegger, Joachim; Maier, Andreas

2018-05-01

This brief proposes a truncated distance (TL1) kernel, which results in a classifier that is nonlinear in the global region but is linear in each subregion. With this kernel, the subregion structure can be trained using all the training data and local linear classifiers can be established simultaneously. The TL1 kernel has good adaptiveness to nonlinearity and is suitable for problems which require different nonlinearities in different areas. Though the TL1 kernel is not positive semidefinite, some classical kernel learning methods are still applicable which means that the TL1 kernel can be directly used in standard toolboxes by replacing the kernel evaluation. In numerical experiments, the TL1 kernel with a pregiven parameter achieves similar or better performance than the radial basis function kernel with the parameter tuned by cross validation, implying the TL1 kernel a promising nonlinear kernel for classification tasks.

Organic-inorganic hybrid nanoparticles controlled delivery system for anticancer drugs.

PubMed

Di Martino, Antonio; Guselnikova, Olga A; Trusova, Marina E; Postnikov, Pavel S; Sedlarik, Vladimir

2017-06-30

The use of organic-inorganic hybrid nanocarriers for controlled release of anticancer drugs has been gained a great interest, in particular, to improve the selectivity and efficacy of the drugs. In this study, iron oxide nanoparticles were prepared then surface modified via diazonium chemistry and coated with chitosan, and its derivative chitosan-grafted polylactic acid. The purpose was to increase the stability of the nanoparticles in physiological solution, heighten drug-loading capacity, prolong the release, reduce the initial burst effect and improve in vitro cytotoxicity of the model drug doxorubicin. The materials were characterized by DLS, ζ-potential, SEM, TGA, magnetization curves and release kinetics studies. Results confirmed the spherical shape, the presence of the coat and the advantages of using chitosan, particularly its amphiphilic derivative, as a coating agent, thereby surpassing the qualities of simple iron oxide nanoparticles. The coated nanoparticles exhibited great stability and high encapsulation efficiency for doxorubicin, at over 500μg per mg of carrier. Moreover, the intensity of the initial burst was clearly diminished after coating, hence represents an advantage of using the hybrid system over simple iron oxide nanoparticles. Cytotoxicity studies demonstrate the increase in cytotoxicity of doxorubicin when loaded in nanoparticles, indirectly proving the role played by the carrier and its surface properties in cell uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

Electric double layer electrostatics of pH-responsive spherical polyelectrolyte brushes in the decoupled regime.

PubMed

Li, Hao; Chen, Guang; Das, Siddhartha

2016-11-01

Understanding the behavior and properties of spherical polyelectrolyte brushes (SPEBs), which are polyelectrolyte brushes grafted to a spherical core, is fundamental to many applications in biomedical, chemical and petroleum engineering as well as in pharmaceutics. In this paper, we study the pH-responsive electrostatics of such SPEBs in the decoupled regime. In the first part of the paper, we derive the scaling conditions in terms of the grafting density of the PEs on the spherical core that ensure that the analysis can be performed in the decoupled regime. In such a regime the elastic and the excluded volume effects of polyelectrolyte brushes (PEBs) can be decoupled from the electrostatic effects associated with the PE charge and the induced EDL. As a consequence the PE brush height, assumed to be dictated by the balance of the elastic and excluded volume effects, can be independent of the electrostatic effects. In the second part, we quantify the pH-responsive electrostatics of the SPEBs - we pinpoint that the radial monomer distribution for a given brush molecule exhibit a non-unique cubic distribution that decays away from the spherical core. Such a monomer distribution ensures that the hydrogen ion concentration is appropriately accounted for in the description of the SPEB thermodynamics. We anticipate that the present analysis, which provides possibly one of the first models for probing the electrostatics of pH-responsive SPEBs in a thermodynamically-consistent framework, will be vital for understanding the behavior of a large number of entities ranging from PE-coated NPs and stealth liposomes to biomolecules like bacteria and viruses. Copyright © 2016 Elsevier B.V. All rights reserved.

A Novel Extreme Learning Machine Classification Model for e-Nose Application Based on the Multiple Kernel Approach

PubMed Central

Jian, Yulin; Huang, Daoyu; Yan, Jia; Lu, Kun; Huang, Ying; Wen, Tailai; Zeng, Tanyue; Zhong, Shijie; Xie, Qilong

2017-01-01

A novel classification model, named the quantum-behaved particle swarm optimization (QPSO)-based weighted multiple kernel extreme learning machine (QWMK-ELM), is proposed in this paper. Experimental validation is carried out with two different electronic nose (e-nose) datasets. Being different from the existing multiple kernel extreme learning machine (MK-ELM) algorithms, the combination coefficients of base kernels are regarded as external parameters of single-hidden layer feedforward neural networks (SLFNs). The combination coefficients of base kernels, the model parameters of each base kernel, and the regularization parameter are optimized by QPSO simultaneously before implementing the kernel extreme learning machine (KELM) with the composite kernel function. Four types of common single kernel functions (Gaussian kernel, polynomial kernel, sigmoid kernel, and wavelet kernel) are utilized to constitute different composite kernel functions. Moreover, the method is also compared with other existing classification methods: extreme learning machine (ELM), kernel extreme learning machine (KELM), k-nearest neighbors (KNN), support vector machine (SVM), multi-layer perceptron (MLP), radical basis function neural network (RBFNN), and probabilistic neural network (PNN). The results have demonstrated that the proposed QWMK-ELM outperforms the aforementioned methods, not only in precision, but also in efficiency for gas classification. PMID:28629202

Time-Distance Analysis of Deep Solar Convection

NASA Technical Reports Server (NTRS)

Duvall, T. L., Jr.; Hanasoge, S. M.

2011-01-01

Recently it was shown by Hanasoge, Duvall, and DeRosa (2010) that the upper limit to convective flows for spherical harmonic degrees l

Cosine beamforming

NASA Astrophysics Data System (ADS)

Ruigrok, Elmer; Wapenaar, Kees

2014-05-01

In various application areas, e.g., seismology, astronomy and geodesy, arrays of sensors are used to characterize incoming wavefields due to distant sources. Beamforming is a general term for phased-adjusted summations over the different array elements, for untangling the directionality and elevation angle of the incoming waves. For characterizing noise sources, beamforming is conventionally applied with a temporal Fourier and a 2D spatial Fourier transform, possibly with additional weights. These transforms become aliased for higher frequencies and sparser array-element distributions. As a partial remedy, we derive a kernel for beamforming crosscorrelated data and call it cosine beamforming (CBF). By applying beamforming not directly to the data, but to crosscorrelated data, the sampling is effectively increased. We show that CBF, due to this better sampling, suffers less from aliasing and yields higher resolution than conventional beamforming. As a flip-side of the coin, the CBF output shows more smearing for spherical waves than conventional beamforming.

Fast and accurate Voronoi density gridding from Lagrangian hydrodynamics data

NASA Astrophysics Data System (ADS)

Petkova, Maya A.; Laibe, Guillaume; Bonnell, Ian A.

2018-01-01

Voronoi grids have been successfully used to represent density structures of gas in astronomical hydrodynamics simulations. While some codes are explicitly built around using a Voronoi grid, others, such as Smoothed Particle Hydrodynamics (SPH), use particle-based representations and can benefit from constructing a Voronoi grid for post-processing their output. So far, calculating the density of each Voronoi cell from SPH data has been done numerically, which is both slow and potentially inaccurate. This paper proposes an alternative analytic method, which is fast and accurate. We derive an expression for the integral of a cubic spline kernel over the volume of a Voronoi cell and link it to the density of the cell. Mass conservation is ensured rigorously by the procedure. The method can be applied more broadly to integrate a spherically symmetric polynomial function over the volume of a random polyhedron.

Effect of tropospheric aerosols upon atmospheric infrared cooling rates

NASA Technical Reports Server (NTRS)

Harshvardhan, MR.; Cess, R. D.

1978-01-01

The effect of tropospheric aerosols on atmospheric infrared cooling rates is investigated by the use of recent models of infrared gaseous absorption. A radiative model of the atmosphere that incorporates dust as an absorber and scatterer of infrared radiation is constructed by employing the exponential kernel approximation to the radiative transfer equation. Scattering effects are represented in terms of a single scattering albedo and an asymmetry factor. The model is applied to estimate the effect of an aerosol layer made of spherical quartz particles on the infrared cooling rate. Calculations performed for a reference wavelength of 0.55 microns show an increased greenhouse effect, where the net upward flux at the surface is reduced by 10% owing to the strongly enhanced downward emission. There is a substantial increase in the cooling rate near the surface, but the mean cooling rate throughout the lower troposphere was only 10%.

Gabor-based kernel PCA with fractional power polynomial models for face recognition.

PubMed

Liu, Chengjun

2004-05-01

This paper presents a novel Gabor-based kernel Principal Component Analysis (PCA) method by integrating the Gabor wavelet representation of face images and the kernel PCA method for face recognition. Gabor wavelets first derive desirable facial features characterized by spatial frequency, spatial locality, and orientation selectivity to cope with the variations due to illumination and facial expression changes. The kernel PCA method is then extended to include fractional power polynomial models for enhanced face recognition performance. A fractional power polynomial, however, does not necessarily define a kernel function, as it might not define a positive semidefinite Gram matrix. Note that the sigmoid kernels, one of the three classes of widely used kernel functions (polynomial kernels, Gaussian kernels, and sigmoid kernels), do not actually define a positive semidefinite Gram matrix either. Nevertheless, the sigmoid kernels have been successfully used in practice, such as in building support vector machines. In order to derive real kernel PCA features, we apply only those kernel PCA eigenvectors that are associated with positive eigenvalues. The feasibility of the Gabor-based kernel PCA method with fractional power polynomial models has been successfully tested on both frontal and pose-angled face recognition, using two data sets from the FERET database and the CMU PIE database, respectively. The FERET data set contains 600 frontal face images of 200 subjects, while the PIE data set consists of 680 images across five poses (left and right profiles, left and right half profiles, and frontal view) with two different facial expressions (neutral and smiling) of 68 subjects. The effectiveness of the Gabor-based kernel PCA method with fractional power polynomial models is shown in terms of both absolute performance indices and comparative performance against the PCA method, the kernel PCA method with polynomial kernels, the kernel PCA method with fractional power polynomial models, the Gabor wavelet-based PCA method, and the Gabor wavelet-based kernel PCA method with polynomial kernels.

Impact of a nonuniform charge distribution on virus assembly

NASA Astrophysics Data System (ADS)

Li, Siyu; Erdemci-Tandogan, Gonca; Wagner, Jef; van der Schoot, Paul; Zandi, Roya

2017-08-01

Many spherical viruses encapsulate their genomes in protein shells with icosahedral symmetry. This process is spontaneous and driven by electrostatic interactions between positive domains on the virus coat proteins and the negative genomes. We model the effect of the nonuniform icosahedral charge distribution from the protein shell instead using a mean-field theory. We find that this nonuniform charge distribution strongly affects the optimal genome length and that it can explain the experimentally observed phenomenon of overcharging of virus and viruslike particles.

Scanning Electron Microscopy and Petrography of Glassy Particles Produced by Lava Fountain Eruptions. Ph.D. Thesis - Final Report

NASA Technical Reports Server (NTRS)

Ladle, G. H.

1978-01-01

A conceptual model of a lava fountain consists of a vent, spatter ramparts, fountain column, downwind plume and associated pumice deposits. Glassy particles produced by lava fountain eruptions consist primarily of sideromelane glass and minor to moderate amounts of vesicles and crystals. Particles are classified on the basis of morphology as: (1) spherical, (2) elongate, (3) glass-coated mineral grain, (4) shard, (5) reticulite, (6) composite particle, and (7) lithic fragment.

7 CFR 981.7 - Edible kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Edible kernel. 981.7 Section 981.7 Agriculture... Regulating Handling Definitions § 981.7 Edible kernel. Edible kernel means a kernel, piece, or particle of almond kernel that is not inedible. [41 FR 26852, June 30, 1976] ...

Kernel K-Means Sampling for Nyström Approximation.

PubMed

He, Li; Zhang, Hong

2018-05-01

A fundamental problem in Nyström-based kernel matrix approximation is the sampling method by which training set is built. In this paper, we suggest to use kernel -means sampling, which is shown in our works to minimize the upper bound of a matrix approximation error. We first propose a unified kernel matrix approximation framework, which is able to describe most existing Nyström approximations under many popular kernels, including Gaussian kernel and polynomial kernel. We then show that, the matrix approximation error upper bound, in terms of the Frobenius norm, is equal to the -means error of data points in kernel space plus a constant. Thus, the -means centers of data in kernel space, or the kernel -means centers, are the optimal representative points with respect to the Frobenius norm error upper bound. Experimental results, with both Gaussian kernel and polynomial kernel, on real-world data sets and image segmentation tasks show the superiority of the proposed method over the state-of-the-art methods.

Apoptosis in liver cancer (HepG2) cells induced by functionalized gold nanoparticles.

PubMed

Ashokkumar, Thirunavukkarasu; Prabhu, Durai; Geetha, Ravi; Govindaraju, Kasivelu; Manikandan, Ramar; Arulvasu, Chinnasamy; Singaravelu, Ganesan

2014-11-01

An ethnopharmacological approach for biosynthesis of gold nanoparticles is being demonstrated using seed coat of Cajanus cajan. Medicinal value of capping molecule investigated for anticancer activity and results disclose its greater potential. The active principle of the seed coat [3-butoxy-2-hydroxypropyl 2-(2,4-dihydroxyphenyl) acetate] is elucidated. Rapid one-step synthesis yields highly stable, monodisperse (spherical) gold nanoparticles in the size ranging from 9 to 41 nm. Anticancer activity has been studied using liver cancer cells and cytotoxic mechanism has been evaluated using MTT, Annexin-V/PI Double-Staining Assay, Cell cycle, Comet assay and Flow cytometric analysis for apoptosis. The present investigation will open up a new possibility of functionalizing gold nanoparticles for apoptosis studies in liver cancer cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanostructured Ag+-substituted fluorhydroxyapatite-TiO2 coatings for enhanced bactericidal effects and osteoinductivity of Ti for biomedical applications

PubMed Central

Chang, Xiaotong; Wang, Zhenhui; Zhang, Xuejiao; Han, Shuguang; Su, Zhuobin; Yang, Hejie; Yang, Dongdong; Zhang, Xiaojun

2018-01-01

Background Poor mechanical properties, undesirable fast dissolution rate, and lack of antibacterial activity limit the application of hydroxyapatite (HA) as an implant coating material. To overcome these limitations, a hybrid coating of Ag+-substituted fluorhydroxyapatite and titania nanotube (TNT) was prepared. Methods The incorporation of silver into the HA-TiO2 hybrid coating improves its antimicrobial properties. The addition of F as a second binary element increases the structural stability of the coating. The TNT/F-and-Ag-substituted HA (FAgHA) bilayer coating on the Ti substrate was confirmed by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Results The results indicate that the FAgHA/TNT nanocomposite coating has a dense and uniform morphology with a nano-rod-like structure. The solubility measurement result shows that the substitution of F− ions into the AgHA structure has a positive effect on the dissolution resistance of HA. The adhesion strength of FAgHA/TNT has significantly increased because of the interlocking of the roughened surface with nano-rod-like particles that entered into the voids of the TiO2 nanotubes. Compared with that of the bare Ti, the corrosion current density of FAgHA/TNT-coated Ti substrate decreased from 3.71 to 0.18 μA, and its corrosion resistance increased by almost two orders of magnitude. Moreover, despite pure HA, the FAgHA killed all viable Staphylococcus aureus after 24 hours of incubation. Although the fabricated FAgHA/TNT coating is hydrophobic, it induced deposition of the typical spherical apatite when immersed in a simulated body fluid (SBF); the osteoblasts spread very well on the surface of the coating. In addition, in vitro cell culture tests demonstrated cell viability and alkaline phosphatase (ALP) similar to pure HA, which indicated good cytocompatibility. Interestingly, compared with bare Ti, FAgHA/TNT-coated Ti surface was innocent for cell vitality and even more beneficial for cell osteogenesis in vitro. Conclusion Enhancing the osseointegration and preventing infection in implants, the FAgHA/TNT-coated Ti makes implants more successful. PMID:29760549

Initial results from safety testing of US AGR-2 irradiation test fuel

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

Morris, Robert Noel; Hunn, John D.; Baldwin, Charles A.

Two cylindrical compacts containing tristructural isotropic (TRISO)-coated particles with kernels that contained a mixture of uranium carbide and uranium oxide (UCO) and two compacts with UO 2-kernel TRISO particles have undergone 1600°C safety testing. These compacts were irradiated in the US Advanced Gas Reactor Fuel Development and Qualification Program's second irradiation test (AGR-2). The time-dependent releases of several radioisotopes ( 110mAg, 134Cs, 137Cs, 154Eu, 155Eu, 90Sr, and 85Kr) were monitored while heating the fuel specimens to 1600°C in flowing helium for 300 h. The UCO compacts behaved similarly to previously reported 1600°C-safety-tested UCO compacts from the AGR-1 irradiation. No failedmore » TRISO or failed SiC were detected (based on krypton and cesium release), and cesium release through intact SiC was very low. Release behavior of silver, europium, and strontium appeared to be dominated by inventory originally released through intact coating layers during irradiation but retained in the compact matrix until it was released during safety testing. Both UO 2 compacts exhibited cesium release from multiple particles whose SiC failed during the safety test. Europium and strontium release from these two UO 2 compacts appeared to be dominated by release from the particles with failed SiC. Silver release was characteristically like the release from the UCO compacts in that an initial release of the majority of silver trapped in the matrix occurred during ramping to 1600°C. However, additional silver release was observed later in the safety testing due to the UO 2 TRISO with failed SiC. Failure of the SiC layer in the UO 2 fuel appears to have been dominated by CO corrosion, as opposed to the palladium degradation observed in AGR-1 UCO fuel.« less

Initial results from safety testing of US AGR-2 irradiation test fuel

DOE PAGES

Morris, Robert Noel; Hunn, John D.; Baldwin, Charles A.; ...

2017-08-18

Two cylindrical compacts containing tristructural isotropic (TRISO)-coated particles with kernels that contained a mixture of uranium carbide and uranium oxide (UCO) and two compacts with UO 2-kernel TRISO particles have undergone 1600°C safety testing. These compacts were irradiated in the US Advanced Gas Reactor Fuel Development and Qualification Program's second irradiation test (AGR-2). The time-dependent releases of several radioisotopes ( 110mAg, 134Cs, 137Cs, 154Eu, 155Eu, 90Sr, and 85Kr) were monitored while heating the fuel specimens to 1600°C in flowing helium for 300 h. The UCO compacts behaved similarly to previously reported 1600°C-safety-tested UCO compacts from the AGR-1 irradiation. No failedmore » TRISO or failed SiC were detected (based on krypton and cesium release), and cesium release through intact SiC was very low. Release behavior of silver, europium, and strontium appeared to be dominated by inventory originally released through intact coating layers during irradiation but retained in the compact matrix until it was released during safety testing. Both UO 2 compacts exhibited cesium release from multiple particles whose SiC failed during the safety test. Europium and strontium release from these two UO 2 compacts appeared to be dominated by release from the particles with failed SiC. Silver release was characteristically like the release from the UCO compacts in that an initial release of the majority of silver trapped in the matrix occurred during ramping to 1600°C. However, additional silver release was observed later in the safety testing due to the UO 2 TRISO with failed SiC. Failure of the SiC layer in the UO 2 fuel appears to have been dominated by CO corrosion, as opposed to the palladium degradation observed in AGR-1 UCO fuel.« less

Exploiting graph kernels for high performance biomedical relation extraction.

PubMed

Panyam, Nagesh C; Verspoor, Karin; Cohn, Trevor; Ramamohanarao, Kotagiri

2018-01-30

Relation extraction from biomedical publications is an important task in the area of semantic mining of text. Kernel methods for supervised relation extraction are often preferred over manual feature engineering methods, when classifying highly ordered structures such as trees and graphs obtained from syntactic parsing of a sentence. Tree kernels such as the Subset Tree Kernel and Partial Tree Kernel have been shown to be effective for classifying constituency parse trees and basic dependency parse graphs of a sentence. Graph kernels such as the All Path Graph kernel (APG) and Approximate Subgraph Matching (ASM) kernel have been shown to be suitable for classifying general graphs with cycles, such as the enhanced dependency parse graph of a sentence. In this work, we present a high performance Chemical-Induced Disease (CID) relation extraction system. We present a comparative study of kernel methods for the CID task and also extend our study to the Protein-Protein Interaction (PPI) extraction task, an important biomedical relation extraction task. We discuss novel modifications to the ASM kernel to boost its performance and a method to apply graph kernels for extracting relations expressed in multiple sentences. Our system for CID relation extraction attains an F-score of 60%, without using external knowledge sources or task specific heuristic or rules. In comparison, the state of the art Chemical-Disease Relation Extraction system achieves an F-score of 56% using an ensemble of multiple machine learning methods, which is then boosted to 61% with a rule based system employing task specific post processing rules. For the CID task, graph kernels outperform tree kernels substantially, and the best performance is obtained with APG kernel that attains an F-score of 60%, followed by the ASM kernel at 57%. The performance difference between the ASM and APG kernels for CID sentence level relation extraction is not significant. In our evaluation of ASM for the PPI task, ASM performed better than APG kernel for the BioInfer dataset, in the Area Under Curve (AUC) measure (74% vs 69%). However, for all the other PPI datasets, namely AIMed, HPRD50, IEPA and LLL, ASM is substantially outperformed by the APG kernel in F-score and AUC measures. We demonstrate a high performance Chemical Induced Disease relation extraction, without employing external knowledge sources or task specific heuristics. Our work shows that graph kernels are effective in extracting relations that are expressed in multiple sentences. We also show that the graph kernels, namely the ASM and APG kernels, substantially outperform the tree kernels. Among the graph kernels, we showed the ASM kernel as effective for biomedical relation extraction, with comparable performance to the APG kernel for datasets such as the CID-sentence level relation extraction and BioInfer in PPI. Overall, the APG kernel is shown to be significantly more accurate than the ASM kernel, achieving better performance on most datasets.

7 CFR 810.2202 - Definition of other terms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... kernels, foreign material, and shrunken and broken kernels. The sum of these three factors may not exceed... the removal of dockage and shrunken and broken kernels. (g) Heat-damaged kernels. Kernels, pieces of... sample after the removal of dockage and shrunken and broken kernels. (h) Other grains. Barley, corn...

7 CFR 981.8 - Inedible kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Inedible kernel. 981.8 Section 981.8 Agriculture... Regulating Handling Definitions § 981.8 Inedible kernel. Inedible kernel means a kernel, piece, or particle of almond kernel with any defect scored as serious damage, or damage due to mold, gum, shrivel, or...

7 CFR 51.1415 - Inedible kernels.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Inedible kernels. 51.1415 Section 51.1415 Agriculture... Standards for Grades of Pecans in the Shell 1 Definitions § 51.1415 Inedible kernels. Inedible kernels means that the kernel or pieces of kernels are rancid, moldy, decayed, injured by insects or otherwise...

An Approximate Approach to Automatic Kernel Selection.

PubMed

Ding, Lizhong; Liao, Shizhong

2016-02-02

Kernel selection is a fundamental problem of kernel-based learning algorithms. In this paper, we propose an approximate approach to automatic kernel selection for regression from the perspective of kernel matrix approximation. We first introduce multilevel circulant matrices into automatic kernel selection, and develop two approximate kernel selection algorithms by exploiting the computational virtues of multilevel circulant matrices. The complexity of the proposed algorithms is quasi-linear in the number of data points. Then, we prove an approximation error bound to measure the effect of the approximation in kernel matrices by multilevel circulant matrices on the hypothesis and further show that the approximate hypothesis produced with multilevel circulant matrices converges to the accurate hypothesis produced with kernel matrices. Experimental evaluations on benchmark datasets demonstrate the effectiveness of approximate kernel selection.

Plasma-assisted deposition of microcapsule containing Aloe vera extract for cosmeto-textiles

NASA Astrophysics Data System (ADS)

Nascimento do Carmo, S.; Zille, A.; Souto, A. P.

2017-10-01

Dielectric Barrier Discharge (DBD) atmospheric-pressure plasma was employed to enhance the deposition of commercial microcapsules (MCs) containing Aloe vera extract onto a cotton/polyester (50:50) fabric. DBD conditions were optimized in term of energy dosage and contact angle. The MCs were applied by padding and printing methods and the coatings were characterized in terms of SEM and FTIR. MCs display a spherical shape with size between 2 and 8 μm with an average wall thickness of 0.5 μm. The MCs applied by printing and pretreated with a plasma dosage of 1.6 kW m2 min-1 showed the best results with an increased adhesion of 200% and significant penetration of MCs into the fibres network. Plasma printed fabric retained 230% more MCs than untreated fabric after 10 washing cycles. However, the coating resistance between unwashed and washed samples was only improved by 5%. Considering the fact that no binder or crosslinking agents were used, the DBD plasma-assisted deposition of MCs revealed to be a promising environmental safe and low cost coating technology.

Rapid fabrication of TiO2@carboxymethyl cellulose coatings capable of shielding UV, antifog and delaying support aging.

PubMed

Li, Xiaozhou; Lv, Junping; Li, Dehuai; Wang, Lin

2017-08-01

Agricultural plastic films capable of shielding UV, filtering visible light and antifog are important to prolong their life and protect safeties of agriculturists and crops. In this work, high stable and small size TiO 2 @polymer nanoparticles (NPs) were prepared by an efficient one-pot microwave synthesis using titanic sulfate as Ti resource, carboxymethyl cellulose sodium (CMC) as complexing agent and stabilizer. The TiO 2 @CMC NPs obtained were then utilized to fabricate poly(ethylene imine) (PEI)/TiO 2 @CMC coatings on the surface of polypropylene films by a layer-by-layer assembly technique. The TiO 2 @CMC NPs show rapid deposition rate because small, spherical and anion-rich TiO 2 @CMC NPs possess large specific surface area and fast diffusion rate. More importantly, property experiments confirm that (PEI/TiO 2 @CMC)*15 coatings can not only effectively shield UV rays, filter visible light and prevent fogging but also delay the aging of their supports. Copyright © 2017 Elsevier Ltd. All rights reserved.

Low cytotoxicity of anisotropic gold nanoparticles coated with lysine on peripheral blood mononuclear cells "in vitro".

PubMed

Avila-Alejo, Jorge O; González-Palomo, Ana K; Plascencia-Villa, Germán; José-Yacamán, Miguel; Navarro-Contreras, Hugo R; Pérez-Maldonado, Iván N

2017-12-01

The aim of this study was to evaluate the cytotoxic effects of anisotropic (non spherical morphologies) gold nanoparticles coated with the amino acid Lysine (Lys) on peripheral blood mononuclear cells (PBMC) "in vitro". Gold (Au) nanoparticles tested in this study were synthesized by a seed-mediated growth using Lys as a structure and shape directing agent. Cytotoxic effects were evaluated by cell viability (resazurin assay), reactive oxygen species (ROS) induction (2',7'-dichlorofluorescein diacetate assay), DNA damage (comet assay) and apoptosis/necrosis (AnnexinV/propidium iodide assay) after PBMC were exposed to increasing concentrations (10, 25, 50, 100, and 250μM) of AuNPs coated with Lys (AuNPs-Lys) at different exposure times (3, 6, 12, and 24h). The results demonstrated that AuNPs-Lys exhibited low cytotoxicity towards PBMC, (high cell viability), with low levels of ROS, DNA damage and apoptosis/necrosis detected after treatment. These data suggest that AuNPs-Lys, might be viable for biomedical application subject to further investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of biodegradable PLGA nanoparticles surface engineered with hyaluronic acid for targeted delivery of paclitaxel to triple negative breast cancer cells.

PubMed

Cerqueira, Brenda Brenner S; Lasham, Annette; Shelling, Andrew N; Al-Kassas, Raida

2017-07-01

This study aimed at development of poly (lactic-co-glycolic acid) (PLGA) nanoparticles embedded with paclitaxel and coated with hyaluronic acid (HA-PTX-PLGA) to actively target the drug to a triple negative breast cancer cells. Nanoparticles were successfully fabricated using a modified oil-in-water emulsion method. The effect of various formulations parameters on the physicochemical properties of the nanoparticles was investigated. SEM imaging confirmed the spherical shape and nano-scale size of the nanoparticles. A sustained drug release profile was obtained and enhanced PTX cytotoxicity was observed when MDA-MB-231 cells were incubated with the HA-PTX-PLGA formulation compared to cells incubated with the non-HA coated nanoparticles. Moreover, HA-PLGA nanoparticles exhibited improved cellular uptake, based on a possible receptor mediated endocytosis due to interaction of HA with CD44 receptors when compared to non-coated PLGA nanoparticles. The non-haemolytic potential of the nanoparticles indicated the suitability of the developed formulation for intravenous administration. Copyright © 2017 Elsevier B.V. All rights reserved.

Multifunctional Properties of Cyanate Ester Composites with SiO2 Coated Fe3O4 Fillers

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

Sun, Weixing; Sun, Wuzhu; Kessler, Michael R

2013-02-22

SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E cyanate ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat cyanate ester polymer is largely preserved up to 160 ?C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamicmore » mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent magnetization in these composites.« less

Interfacial effect on the structural and optical properties of pure SnO2 and dual shells (ZnO; SiO2) coated SnO2 core-shell nanospheres for optoelectronic applications

NASA Astrophysics Data System (ADS)

Selvi, N.; Sankar, S.; Dinakaran, K.

2014-12-01

Nanocrystallites of SnO2 core and dual shells (ZnO, SiO2) coated SnO2 core-shell nanospheres were successfully synthesized by co-precipitation method. The as prepared and annealed samples were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM) and UV-Vis analysis. XRD pattern confirms the obtained SnO2 core with tetragonal rutile crystalline structure and the shell ZnO with hexagonal structure. FTIR result shows the functional groups present in the samples. The spherical morphology and the formation of the core-shell structures have been confirmed by HRTEM measurements. The UV-Vis showed that band gap is red shifted for as-prepared and the shells coated core-shell samples. From this investigation it can be concluded that the surface modification with different metal and insulating oxides strongly influences the optical properties of the core-shell materials which enhance their potential applications towards optical devices fabrication.

Colloids with high-definition surface structures

PubMed Central

Chen, Hsien-Yeh; Rouillard, Jean-Marie; Gulari, Erdogan; Lahann, Joerg

2007-01-01

Compared with the well equipped arsenal of surface modification methods for flat surfaces, techniques that are applicable to curved, colloidal surfaces are still in their infancy. This technological gap exists because spin-coating techniques used in traditional photolithographic processes are not applicable to the curved surfaces of spherical objects. By replacing spin-coated photoresist with a vapor-deposited, photodefinable polymer coating, we have now fabricated microstructured colloids with a wide range of surface patterns, including asymmetric and chiral surface structures, that so far were typically reserved for flat substrates. This high-throughput method can yield surface-structured colloidal particles at a rate of ≈107 to 108 particles per operator per day. Equipped with spatially defined binding pockets, microstructured colloids can engage in programmable interactions, which can lead to directed self-assembly. The ability to create a wide range of colloids with both simple and complex surface patterns may contribute to the genesis of previously unknown colloidal structures and may have important technological implications in a range of different applications, including photonic and phononic materials or chemical sensors. PMID:17592149

Effects of Forged Stock and Pure Aluminum Coating on Cryogenic Performance of Heat Treated Aluminum Mirrors

NASA Technical Reports Server (NTRS)

Toland, Ronald; Ohl, Raymond G.; Barthelmy, Michael P.; Zewari, S. Wahid; Greenhouse, Matthew A.; MacKenty, John W.

2003-01-01

In spite of its baseline mechanical stress relief, aluminum 6061-T651 harbors some residual stress that may relieve and distort mirror figure to unacceptable levels at cryogenic operating temperatures unless relieved during fabrication. Cryogenic instruments using aluminum mirrors for both ground-based and space IR astronomy have employed a variety of heat treatment formulae, with mixed results. We present the results of an on-going test program designed to empirically determine the effects of different stress relief procedures for aluminum mirrors. Earlier test results identified a preferred heat treatment for flat and spherical mirrors diamond turned from blanks cut out of Al6061-T651 plate stock. Further tests have been performed on mirrors from forged stock and one set from plate stock coated with Alumiplate(TM) aluminum coating to measure the effect of these variables on cryogenic performance. The mirrors are tested for figure error and radius of curvature at room temperature and at 80 K for three thermal cycles. We correlate the results of our optical testing with heat treatment and metallographic data.

Mechanics of receptor-mediated endocytosis

NASA Astrophysics Data System (ADS)

Gao, Huajian; Shi, Wendong; Freund, Lambert B.

2005-07-01

Most viruses and bioparticles endocytosed by cells have characteristic sizes in the range of tens to hundreds of nanometers. The process of viruses entering and leaving animal cells is mediated by the binding interaction between ligand molecules on the viral capid and their receptor molecules on the cell membrane. How does the size of a bioparticle affect receptor-mediated endocytosis? Here, we study how a cell membrane containing diffusive mobile receptors wraps around a ligand-coated cylindrical or spherical particle. It is shown that particles in the size range of tens to hundreds of nanometers can enter or exit cells via wrapping even in the absence of clathrin or caveolin coats, and an optimal particles size exists for the smallest wrapping time. This model can also be extended to include the effect of clathrin coat. The results seem to show broad agreement with experimental observations. Author contributions: H.G. and L.B.F. designed research; H.G., W.S., and L.B.F. performed research; and H.G., W.S., and L.B.F. wrote the paper.Abbreviations: CNT, carbon nanotube; SWNT, single-walled nanotube.

Physicochemical characterization of 3,6-diHydroxyflavone binding BSA immobilized on PEG-coated silver nanoparticles

NASA Astrophysics Data System (ADS)

Voicescu, Mariana; Ionescu, Sorana; Calderon-Moreno, Jose M.; Nistor, Cristina L.

2017-02-01

Studies based on silver nanoparticles (SNPs) and polyethylene glycols (PEGs) are mainly in the pharmaceutical field, with PEG as good "vehicle" to transport protein-based drugs. In this work, physicochemical characteristics of 3,6-diHydroxyflavone (3,6-diHF) binding bovine serum albumin (BSA) on PEG (Tween20, L64, and Myrj52)-coated SNPs have been investigated by steady-state and time-resolved fluorescence spectroscopy. These interactions give rise to the formation of intermolecular and intramolecular H bonds. As a subject of interest, the effect of temperature (30-60 °C) on the H bonds was studied by steady-state fluorescence. The size distribution and zeta potential of SNPs were determined by dynamic light scattering (DLS). Scanning electron microscopy (SEM) analysis revealed the spherical nature of particles with average diameter 40-80 nm. The structure, stability, dynamics, and conformational changes in adsorbed BSA protein on the PEG-coated SNPs surface have been also investigated by steady-state/lifetime fluorescence and circular dichroism spectroscopy. The results have relevance in the oxidative stress and drug delivery processes.

Coupling individual kernel-filling processes with source-sink interactions into GREENLAB-Maize.

PubMed

Ma, Yuntao; Chen, Youjia; Zhu, Jinyu; Meng, Lei; Guo, Yan; Li, Baoguo; Hoogenboom, Gerrit

2018-02-13

Failure to account for the variation of kernel growth in a cereal crop simulation model may cause serious deviations in the estimates of crop yield. The goal of this research was to revise the GREENLAB-Maize model to incorporate source- and sink-limited allocation approaches to simulate the dry matter accumulation of individual kernels of an ear (GREENLAB-Maize-Kernel). The model used potential individual kernel growth rates to characterize the individual potential sink demand. The remobilization of non-structural carbohydrates from reserve organs to kernels was also incorporated. Two years of field experiments were conducted to determine the model parameter values and to evaluate the model using two maize hybrids with different plant densities and pollination treatments. Detailed observations were made on the dimensions and dry weights of individual kernels and other above-ground plant organs throughout the seasons. Three basic traits characterizing an individual kernel were compared on simulated and measured individual kernels: (1) final kernel size; (2) kernel growth rate; and (3) duration of kernel filling. Simulations of individual kernel growth closely corresponded to experimental data. The model was able to reproduce the observed dry weight of plant organs well. Then, the source-sink dynamics and the remobilization of carbohydrates for kernel growth were quantified to show that remobilization processes accompanied source-sink dynamics during the kernel-filling process. We conclude that the model may be used to explore options for optimizing plant kernel yield by matching maize management to the environment, taking into account responses at the level of individual kernels. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Unconventional protein sources: apricot seed kernels.

PubMed

Gabrial, G N; El-Nahry, F I; Awadalla, M Z; Girgis, S M

1981-09-01

Hamawy apricot seed kernels (sweet), Amar apricot seed kernels (bitter) and treated Amar apricot kernels (bitterness removed) were evaluated biochemically. All kernels were found to be high in fat (42.2--50.91%), protein (23.74--25.70%) and fiber (15.08--18.02%). Phosphorus, calcium, and iron were determined in all experimental samples. The three different apricot seed kernels were used for extensive study including the qualitative determination of the amino acid constituents by acid hydrolysis, quantitative determination of some amino acids, and biological evaluation of the kernel proteins in order to use them as new protein sources. Weanling albino rats failed to grow on diets containing the Amar apricot seed kernels due to low food consumption because of its bitterness. There was no loss in weight in that case. The Protein Efficiency Ratio data and blood analysis results showed the Hamawy apricot seed kernels to be higher in biological value than treated apricot seed kernels. The Net Protein Ratio data which accounts for both weight, maintenance and growth showed the treated apricot seed kernels to be higher in biological value than both Hamawy and Amar kernels. The Net Protein Ratio for the last two kernels were nearly equal.

A model system for the evaluation of radioimmunoimaging of tumors

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

Koizumi, M.; Endo, K.; Sakahara, H.

1985-05-01

The authors have developed a simple model system that can be used to evaluate methods of radioimmunoimaging of tumors, using human chorionic gonadropin (hCG) as a model antigen, and a monoclonal antibody against hCG ..beta..-subunit as a model antibody. HCG was coated on a polystylene spherical bead with a quarter inch in diameter, and coated beads were washed extensively with phosphate buffered saline, and glycine acid buffer to remove the easily dissociable antigen. HCG-coated beads were put into the subcutaneous tissue on the back of mice. At 24 hr after the transplantation, when serum hCG was not detectable by themore » conventional RIA, radiolabeled antibodies were injected and its bio-distribution monitored. The %ID/g for the hCG coated beads increased to a maximum of 48 hr after the injection of radioiodinad antibody, whereas the %ID/g for most organs decreased with time. As a nonspecific antigen, beads coated with bovine serum albumin were transplanted and its uptake was as low as about one 50th of hCG-coated ones. The %ID/g of radioiodinated monoclonal antibody against human thyroglobulin (a nonspecific antibody) for hCG-coated beads was also negligible. Thus, the localization index (%ID of specific antibody / %ID of nonspecific antibody) reached to 15.0 at 24 hr, 35.5 at 48 hr and 57.8 at 96 hr after the injection. The biodistribution of In-111 labeled specific monoclonal antibody, prepared through the chelation with DTPA, demonstrated similar results with radioiodinated ones. This mouse model system that did not involve the use of tumors, yielded high localization index and reproducibilities and could be used to evaluate different methods for radiolabelng monoclonal antibodies.« less

Effect of insulin-coated trimethyl chitosan nanoparticles on IGF-1, IGF-2, and apoptosis in the hippocampus of diabetic male rats.

PubMed

Kalantarian, Giti; Ziamajidi, Nasrin; Mahjoub, Reza; Goodarzi, Mohammad Taghi; Saidijam, Massoud; Asl, Sara Soleimani; Abbasalipourkabir, Roghayeh

2018-06-06

Subcutaneous injection of insulin can lead to problems such as hypoglycemia and edema. The purpose of this research was to evaluate the effect of oral insulin-coated trimethyl chitosan nanoparticles on control of glycemic status, IGF-1 and IGF-2 levels, and apoptosis in the hippocampus of rats with diabetes mellitus. Insulin-coated trimethyl chitosan nanoparticles were prepared by the complex polyelectrolyte (PEC) method. Insulin loading content, loading efficiency, quantity and quality of particle size were evaluated. In vivo study was performed in different treatment groups of male Wistar rats with diabetes mellitus by insulin-coated trimethyl chitosan nanoparticles or subcutaneous injection of trade insulin. The duration of diabetes was eight weeks and the treatment was started after that time and continued for another two weeks. Body weight, fasting blood glucose (FBS), hippocampal apoptosis, and immunohistochemical (IHC) protein levels of IGF-1 and IGF-2 were assessed at the end of the experiments. The size and polydispersity indexes were 533 nanometers and 0.533, respectively. Insulin coated trimethyl chitosan nanoparticles showed high loading efficiency (97.67% ) and loading content (48.83% ). The spherical shape of nanoparticle was confirmed by transmission electron microscopic (TEM). The amine, amide, ether and aliphatic groups were evaluated using FT-IR spectrophotometer which represented the correctness of the insulin coated trimethyl chitosan nanoparticles. Although the apoptotic index was not changed either by insulin-coated nano-particles or commercial insulin in vivo results showed the efficacy of insulin-coated nanoparticles as well as commercial insulin in compensated weight loss, FBS and protein levels of IGF-1 and IGF-2. The present study showed the efficacy of insulin coated nanoparticle in oral route manner that can be tested in Phase I- III clinical trials. However, a behavioral study could reveal the efficacy of insulin-loaded nanoparticles in the improvement of cognitive changes through the modulation of IGF-1 and IGF-2 levels in the hippocampus.

An introduction to kernel-based learning algorithms.

PubMed

Müller, K R; Mika, S; Rätsch, G; Tsuda, K; Schölkopf, B

2001-01-01

This paper provides an introduction to support vector machines, kernel Fisher discriminant analysis, and kernel principal component analysis, as examples for successful kernel-based learning methods. We first give a short background about Vapnik-Chervonenkis theory and kernel feature spaces and then proceed to kernel based learning in supervised and unsupervised scenarios including practical and algorithmic considerations. We illustrate the usefulness of kernel algorithms by discussing applications such as optical character recognition and DNA analysis.

Detection of Intermediates And Kinetic Control During Assembly of Bacteriophage P22 Procapsid

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

Tuma, R.; Tsuruta, H.; French, K.H.

2009-05-26

Bacteriophage P22 serves as a model for the assembly and maturation of other icosahedral double-stranded DNA viruses. P22 coat and scaffolding proteins assemble in vitro into an icosahedral procapsid, which then expands during DNA packaging (maturation). Efficient in vitro assembly makes this system suitable for design and production of monodisperse spherical nanoparticles (diameter {approx} 50 nm). In this work, we explore the possibility of controlling the outcome of assembly by scaffolding protein engineering. The scaffolding protein exists in monomer-dimer-tetramer equilibrium. We address the role of monomers and dimers in assembly by using three different scaffolding proteins with altered monomer-dimer equilibriummore » (weak dimer, covalent dimer, monomer). The progress and outcome of assembly was monitored by time-resolved X-ray scattering, which allowed us to distinguish between closed shells and incomplete assembly intermediates. Binding of scaffolding monomer activates the coat protein for assembly. Excess dimeric scaffolding protein resulted in rapid nucleation and kinetic trapping yielding incomplete shells. Addition of monomeric wild-type scaffold with excess coat protein completed these metastable shells. Thus, the monomeric scaffolding protein plays an essential role in the elongation phase by activating the coat and effectively lowering its critical concentration for assembly.« less

The realuminizing of the 7-meter-diameter solar simulator collimating mirror

NASA Technical Reports Server (NTRS)

Noller, E. W.

1994-01-01

This paper describes the modification of a three-electron-beam (EB) gun system for vacuum depositing a highly reflective aluminum coating on a 7.01-m (23-ft) -diam nickel-plated aluminum collimating mirror. The mirror is part of the JPL 7.62-m space simulator that was recently modernized with a new high vacuum pumping system, solar lamp power supplies, solar optic lens system, and refurbished collimating mirror. The 7.01-m 12,700-kg (14-ton) spherical collimating mirror was removed from this facility for replating with 381 micron (0.015 in.) of electroless nickel and polished to a specular finish for realuminizing. The space chamber served as the vacuum coating vessel for the realuminizing coating process. The mirror is the primary reflector for the solar simulation system and the aluminized reflective surface is its most critical performance element. The uniformity of thickness and high reflectivity of the coating in visible and near-ultraviolet (UV) light governs the accuracy of the beam for solar testing. The uniformity of the thin-film thickness also controls the durability of the mirror over time. The mirror was polished to a 64-percent reflectivity with a uniformity of 1.5 percent. The performance goal for the aluminizing was 89 percent with +/- 0.5-percent variation over the mirror.

Novel surface-modified nanostructured lipid carriers with partially deacetylated water-soluble chitosan for efficient ocular delivery.

PubMed

Tian, Baocheng; Luo, Qiuhua; Song, Shuangshuang; Liu, Dandan; Pan, Hao; Zhang, Wenji; He, Ling; Ma, Shilin; Yang, Xinggang; Pan, Weisan

2012-03-01

The objective of this study was to propose novel surface-modified nanostructured lipid carriers with partially deacetylated water-soluble chitosan (NLC-PDSC) as an efficient ocular delivery system to improve its transcorneal penetration and precorneal retention. PDSC with a deacetylation degree of around 50% was synthesized using an improved method. NLC loaded with flurbiprofen (FB) were prepared by melt emulsification method. They presented spherical morphology under both transmission electron microscope and scanning electron microscope. After coating with 0.15% (w/v) PDSC solution, the NLC showed a core-shell structure and a reversed zeta potential. The enhanced transcorneal penetration of the coated NLC was evaluated using isolated rabbit corneas, with significantly increased apparent permeability coefficient being 1.40- and 1.75-fold of the NLC and FB phosphate solution (FB-sol; p < 0.05), respectively. Precorneal retention assessed by gamma scintigraphy in vivo showed that the area under the remaining activity-time curve of the PDSC-coated formulation was 1.3-fold of the NLC and 2.4-fold of FB-sol. Moreover, in vivo ocular tolerance study indicated that there was no difference in irritation between the coated and noncoated NLC. In conclusion, novel NLC demonstrate high potential for ocular drug delivery. Copyright © 2011 Wiley Periodicals, Inc.

Surface figure control for coated optics

DOEpatents

Ray-Chaudhuri, Avijit K.; Spence, Paul A.; Kanouff, Michael P.

2001-01-01

A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness.sup.2 /optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members. However, the pedestal optical substrate can be manufactured from a solid piece of material to form a monolith, thus avoiding joints between the sections, or the disk-like base can be formed separately and connected to the connecting section. By way of example, the pedestal optical substrate may be utilized in the fabrication of optics for an extreme ultraviolet (EUV) lithography imaging system, or in any optical system requiring coated optics and substrates with reduced sensitivity to mechanical mounts.

Rational strategy for the atmospheric icing prevention based on chemically functionalized carbon soot coatings

NASA Astrophysics Data System (ADS)

Esmeryan, Karekin D.; Bressler, Ashton H.; Castano, Carlos E.; Fergusson, Christian P.; Mohammadi, Reza

2016-12-01

Although the superhydrophobic surfaces are preferable for passive anti-icing systems, as they provide water shedding before initiation of ice nucleation, their practical usage is still under debate. This is so, as the superhydrophobic materials are not necessarily icephobic and most of the synthesis techniques are characterized with low fabrication scalability. Here, we describe a rational strategy for the atmospheric icing prevention, based on chemically functionalized carbon soot, suitable for large-scale fabrication of superhydrophobic coatings that exhibit and retain icephobicity in harsh operational conditions. This is achieved through a secondary treatment with ethanol and aqueous fluorocarbon solution, which improves the coating's mechanical strength without altering its water repellency. Subsequent experimental analyses on the impact dynamics of icy water droplets on soot coated aluminum and steel sheets show that these surfaces remain icephobic in condensate environments and substrate temperatures down to -35 °C. Furthermore, the soot's icephobicity and non-wettability are retained in multiple icing/de-icing cycles and upon compressed air scavenging, spinning and water jetting with impact velocity of ∼25 m/s. Finally, on frosted soot surfaces, the droplets freeze in a spherical shape and are entirely detached by adding small amount of thermal energy, indicating lower ice adhesion compared to the uncoated metal substrates.

Delayed condensation and frost formation on superhydrophobic carbon soot coatings by controlling the presence of hydrophilic active sites

NASA Astrophysics Data System (ADS)

Esmeryan, Karekin D.; Castano, Carlos E.; Mohammadi, Reza; Lazarov, Yuliyan; Radeva, Ekaterina I.

2018-02-01

Condensation frosting is an undesired natural phenomenon that could be impeded efficiently using appropriate wettability and morphologically patterned surfaces. The icephobic properties of carbon soot and the fabrication scalability of its synthesis method are a good foundation for anti-frosting applications; however, the fundamentals of frost growth and spreading on sooted surfaces have not been examined yet. In this study, we investigate the anti-frosting performance of three groups of superhydrophobic soot coatings by means of 16 MHz quartz crystal microbalances (QCMs). The analysis of the real-time sensor signal of each soot coated QCM pattern shows that frost formation and its propagation velocity depend on the quantity of oxygen functionalities and structural defects in the material. In turn, the reduction of both parameters shifts the onset of frost growth to temperatures below  -20 °C, whereas the interdroplet ice bridging is slowed by a factor of four. Moreover, high-resolution scanning electron micrographs of the samples imply delamination upon defrosting of the soot with spherical-like morphology via polar interactions driven mechanism. These results reveal an opportunity for control of frost incipiency on sooted surfaces by adjusting the synthesis conditions and depositing soot coatings with as low as possible content of hydrophilic active sites.

7 CFR 981.408 - Inedible kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Inedible kernel. 981.408 Section 981.408 Agriculture... Administrative Rules and Regulations § 981.408 Inedible kernel. Pursuant to § 981.8, the definition of inedible kernel is modified to mean a kernel, piece, or particle of almond kernel with any defect scored as...

Design of CT reconstruction kernel specifically for clinical lung imaging

NASA Astrophysics Data System (ADS)

Cody, Dianna D.; Hsieh, Jiang; Gladish, Gregory W.

2005-04-01

In this study we developed a new reconstruction kernel specifically for chest CT imaging. An experimental flat-panel CT scanner was used on large dogs to produce 'ground-truth" reference chest CT images. These dogs were also examined using a clinical 16-slice CT scanner. We concluded from the dog images acquired on the clinical scanner that the loss of subtle lung structures was due mostly to the presence of the background noise texture when using currently available reconstruction kernels. This qualitative evaluation of the dog CT images prompted the design of a new recon kernel. This new kernel consisted of the combination of a low-pass and a high-pass kernel to produce a new reconstruction kernel, called the 'Hybrid" kernel. The performance of this Hybrid kernel fell between the two kernels on which it was based, as expected. This Hybrid kernel was also applied to a set of 50 patient data sets; the analysis of these clinical images is underway. We are hopeful that this Hybrid kernel will produce clinical images with an acceptable tradeoff of lung detail, reliable HU, and image noise.

Quality changes in macadamia kernel between harvest and farm-gate.

PubMed

Walton, David A; Wallace, Helen M

2011-02-01

Macadamia integrifolia, Macadamia tetraphylla and their hybrids are cultivated for their edible kernels. After harvest, nuts-in-shell are partially dried on-farm and sorted to eliminate poor-quality kernels before consignment to a processor. During these operations, kernel quality may be lost. In this study, macadamia nuts-in-shell were sampled at five points of an on-farm postharvest handling chain from dehusking to the final storage silo to assess quality loss prior to consignment. Shoulder damage, weight of pieces and unsound kernel were assessed for raw kernels, and colour, mottled colour and surface damage for roasted kernels. Shoulder damage, weight of pieces and unsound kernel for raw kernels increased significantly between the dehusker and the final silo. Roasted kernels displayed a significant increase in dark colour, mottled colour and surface damage during on-farm handling. Significant loss of macadamia kernel quality occurred on a commercial farm during sorting and storage of nuts-in-shell before nuts were consigned to a processor. Nuts-in-shell should be dried as quickly as possible and on-farm handling minimised to maintain optimum kernel quality. 2010 Society of Chemical Industry.

Uncertainties of aerosol retrieval from neglecting non-sphericity of dust aerosols

NASA Astrophysics Data System (ADS)

Li, Chi; Xue, Yong; Yang, Leiku; Guang, Jie

2013-04-01

The Mie theory is conventionally applied to calculate aerosol optical properties in satellite remote sensing applications, while dust aerosols cannot be well modeled by the Mie calculation for their non-sphericity. It has been cited in Mishchenko et al. (1995; 1997) that neglecting non-sphericity can severely influence aerosol optical depth (AOD, ?) retrieval in case of dust aerosols because of large difference of phase functions under spherical and non-spherical assumptions, whereas this uncertainty has not been thoroughly studied. This paper aims at a better understanding of uncertainties on AOD retrieval caused by aerosol non-sphericity. A dust aerosol model with known refractive index and size distribution is generated from long-term AERONET observations since 1999 over China. Then aerosol optical properties, such as the extinction, phase function, single scattering albedo (SSA) are calculated respectively in the assumption of spherical and non-spherical aerosols. Mie calculation is carried out for spherical assumption, meanwhile for non-spherical aerosol modeling, we adopt the pre-calculated scattering kernels and software package presented by Dubovik et al. (2002; 2006), which describes dust as a shape mixture of randomly oriented polydisperse spheroids. Consequently we generate two lookup tables (LUTspheric and LUTspheroid) from simulated satellite received reflectance at top of atmosphere (TOA) under varieties of observing conditions and aerosol loadings using Second Simulation of a Satellite Signal in the Solar Spectrum - Vector (6SV) code. All the simulations are made at 550 nm, and for simplicity the Lambertian surface is assumed. Using the obtained LUTs we examine the differences of TOA reflectance (Δ?TOA = ?spheric - ?spheroid) under different surface reflectance and aerosol loadings. Afterwards AOD is retrieved using LUTspheric from the simulated TOA reflectance by LUTspheroid in order to detect the retrieval errors (Δ? = ?retreived -?input) induced by straightforwardly utilizing Mie theory in dust aerosol retrieval. As expected we find that the uncertainties mainly result from the obvious difference of phase functions (Pspheric and Pspheroid). Errors may be positive or negative, depending on the specific geometry. In scattering angle (θ) regions where Psphericis greater (30°~85° & 145°~180°), we generally get positive Δ?TOA and negative Δ?, and vice versa (85°~145°). For low aerosol loading (? ~0.25) and black surface, |Δ?TOA| could be greater than 0.004 and 0.012 around θ ~120° and θ ~170°, with |Δ?| of ~0.04 and ~0.12 respectively. In most back scattering cases (θ >100°), the magnitude of Δ? is about ten times that of Δ?TOA, while this ratio (|Δ?|/|Δ?TOA|) significantly reduces to as low as ~0.5 for forward scattering, and can reach ~20 at θ ~145°. Moreover, this errors and |Δ?|/|Δ?TOA| can increase more than ten times as aerosol loading gets higher and surface gets brighter. Therefore we conclude that the neglect of non-sphericity introduces substantial errors on radiative transfer simulation and AOD retrieval. As a result of this study, a representative aspheric aerosol model other than Mie calculation is recommended for inversion algorithms related with dust-like non-spherical aerosols. References Dubovik, O., Holben, B. N., Lapyonok, T., Sinyuk, A., Mishchenko, M. I., Yang, P., and Slutsker, I. (2002). Non-spherical aerosol retrieval method employing light scattering by spheroids. Geophyscal Research Letters, 29(10), 1415, doi:10.1029/2001GL014506. Dubovik, O., Sinyuk, A., Lapyonok, T., Holben, B. N., Mishchenko, M., Yang, P., Eck, T. F., Volten, H., Muñoz, O., Veihelmann, B., van der Zande, W. J., Leon, J.-F., Sorokin, M., and Slutsker, I. (2006). Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. Journal of Geophysical Research, 111, D11208, doi:10.1029/2005JD006619. Mishchenko, M. I., Lacis, A. A., Carlson, B. E., and Travis, L. D. (1995). Nonsphericity of dust-like aerosols: Implications for aerosol remote sensing and climate modeling, Geophyscal Research Letters, 22, 1077- 1080. Mishchenko, M. I., Travis, L. D., Kahn, R. A., and West, R. A. (1997). Modeling phase functions for dustlike tropospheric aerosols using a shape mixture of randomly oriented polydisperse spheroids, Journal of Geophysical Research, 102, 16831- 16847.

A new discriminative kernel from probabilistic models.

PubMed

Tsuda, Koji; Kawanabe, Motoaki; Rätsch, Gunnar; Sonnenburg, Sören; Müller, Klaus-Robert

2002-10-01

Recently, Jaakkola and Haussler (1999) proposed a method for constructing kernel functions from probabilistic models. Their so-called Fisher kernel has been combined with discriminative classifiers such as support vector machines and applied successfully in, for example, DNA and protein analysis. Whereas the Fisher kernel is calculated from the marginal log-likelihood, we propose the TOP kernel derived; from tangent vectors of posterior log-odds. Furthermore, we develop a theoretical framework on feature extractors from probabilistic models and use it for analyzing the TOP kernel. In experiments, our new discriminative TOP kernel compares favorably to the Fisher kernel.

Implementing Kernel Methods Incrementally by Incremental Nonlinear Projection Trick.

PubMed

Kwak, Nojun

2016-05-20

Recently, the nonlinear projection trick (NPT) was introduced enabling direct computation of coordinates of samples in a reproducing kernel Hilbert space. With NPT, any machine learning algorithm can be extended to a kernel version without relying on the so called kernel trick. However, NPT is inherently difficult to be implemented incrementally because an ever increasing kernel matrix should be treated as additional training samples are introduced. In this paper, an incremental version of the NPT (INPT) is proposed based on the observation that the centerization step in NPT is unnecessary. Because the proposed INPT does not change the coordinates of the old data, the coordinates obtained by INPT can directly be used in any incremental methods to implement a kernel version of the incremental methods. The effectiveness of the INPT is shown by applying it to implement incremental versions of kernel methods such as, kernel singular value decomposition, kernel principal component analysis, and kernel discriminant analysis which are utilized for problems of kernel matrix reconstruction, letter classification, and face image retrieval, respectively.

Increasing accuracy of dispersal kernels in grid-based population models

USGS Publications Warehouse

Slone, D.H.

2011-01-01

Dispersal kernels in grid-based population models specify the proportion, distance and direction of movements within the model landscape. Spatial errors in dispersal kernels can have large compounding effects on model accuracy. Circular Gaussian and Laplacian dispersal kernels at a range of spatial resolutions were investigated, and methods for minimizing errors caused by the discretizing process were explored. Kernels of progressively smaller sizes relative to the landscape grid size were calculated using cell-integration and cell-center methods. These kernels were convolved repeatedly, and the final distribution was compared with a reference analytical solution. For large Gaussian kernels (σ > 10 cells), the total kernel error was <10 &sup-11; compared to analytical results. Using an invasion model that tracked the time a population took to reach a defined goal, the discrete model results were comparable to the analytical reference. With Gaussian kernels that had σ ≤ 0.12 using the cell integration method, or σ ≤ 0.22 using the cell center method, the kernel error was greater than 10%, which resulted in invasion times that were orders of magnitude different than theoretical results. A goal-seeking routine was developed to adjust the kernels to minimize overall error. With this, corrections for small kernels were found that decreased overall kernel error to <10-11 and invasion time error to <5%.

Anthraquinones isolated from the browned Chinese chestnut kernels (Castanea mollissima blume)

NASA Astrophysics Data System (ADS)

Zhang, Y. L.; Qi, J. H.; Qin, L.; Wang, F.; Pang, M. X.

2016-08-01

Anthraquinones (AQS) represent a group of secondary metallic products in plants. AQS are often naturally occurring in plants and microorganisms. In a previous study, we found that AQS were produced by enzymatic browning reaction in Chinese chestnut kernels. To find out whether non-enzymatic browning reaction in the kernels could produce AQS too, AQS were extracted from three groups of chestnut kernels: fresh kernels, non-enzymatic browned kernels, and browned kernels, and the contents of AQS were determined. High performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) methods were used to identify two compounds of AQS, rehein(1) and emodin(2). AQS were barely exists in the fresh kernels, while both browned kernel groups sample contained a high amount of AQS. Thus, we comfirmed that AQS could be produced during both enzymatic and non-enzymatic browning process. Rhein and emodin were the main components of AQS in the browned kernels.

Calcium phosphate coating on titanium using laser and plasma spray

NASA Astrophysics Data System (ADS)

Roy, Mangal

Though calcium phosphate (CaP) coated implants are commercially available, its acceptance is still not wide spread due to challenges related to weaker interfacial bonding between metal and ceramic, and low crystallinity of hydroxyapatite (HA). The objectives of this research are to improve interfacial strength, crystallinity, phase purity and bioactivity of CaP coated metallic implants for orthopaedic applications. The rationale is that forming a diffuse and gradient metal-ceramic interface will improve the interfacial strength. Moreover, reducing CaP particles exposure to high temperature during coating preparation, can lead to improvement in both crystallinity and phase purity of CaP. In this study, laser engineered net shaping (LENS(TM)) was used to coat Ti metal with CaP. LENS(TM) processing enabled generation of Ti+TCP (tricalcium phosphate) composite coating with diffused interface, that also increased the coating hardness to 1049+/-112 Hv compared to a substrate hardness of 200+/-15 Hv. In vitro bone cell-material interaction studies confirmed the bioactivity of TCP coatings. Antimicrobial properties of the TCP coatings were improved by silver (Ag) electrodeposition. Along with LENS(TM), radio frequency induction plasma spray, equipped with supersonic plasma nozzle, was used to prepare HA coatings on Ti with improved crystallinity and phase purity. The coating was made of multigrain HA particles of ˜200 nm in size, which consisted of 15--20 nm HA grains. In vitro bone cell-material interaction and in vivo rat model studies confirmed the HA coatings to be bioactive. Furthermore, incorporation of Sr2+ improved bone cell of HA coatings interaction. A combination of LENS(TM) and plasma spray was used to fabricate a compositionally graded HA coatings on Ti where the microstructure varied from pure HA at the surface to pure Ti substrate with a diffused Ti+TCP composite region in between. The plasma spray system was used to synthesize spherical HA nano powder from HA sol, where the production rate was 20 g/h, which is only 16% of the total powder produced. The effects of Sr2+ and Mg2+ doping on bone cell-CaP interaction was further studied with osteoclast cells. Mg2+ doing was found to be an effective way of controlling osteoclast differentiation.

Broken rice kernels and the kinetics of rice hydration and texture during cooking.

PubMed

Saleh, Mohammed; Meullenet, Jean-Francois

2013-05-01

During rice milling and processing, broken kernels are inevitably present, although to date it has been unclear as to how the presence of broken kernels affects rice hydration and cooked rice texture. Therefore, this work intended to study the effect of broken kernels in a rice sample on rice hydration and texture during cooking. Two medium-grain and two long-grain rice cultivars were harvested, dried and milled, and the broken kernels were separated from unbroken kernels. Broken rice kernels were subsequently combined with unbroken rice kernels forming treatments of 0, 40, 150, 350 or 1000 g kg(-1) broken kernels ratio. Rice samples were then cooked and the moisture content of the cooked rice, the moisture uptake rate, and rice hardness and stickiness were measured. As the amount of broken rice kernels increased, rice sample texture became increasingly softer (P < 0.05) but the unbroken kernels became significantly harder. Moisture content and moisture uptake rate were positively correlated, and cooked rice hardness was negatively correlated to the percentage of broken kernels in rice samples. Differences in the proportions of broken rice in a milled rice sample play a major role in determining the texture properties of cooked rice. Variations in the moisture migration kinetics between broken and unbroken kernels caused faster hydration of the cores of broken rice kernels, with greater starch leach-out during cooking affecting the texture of the cooked rice. The texture of cooked rice can be controlled, to some extent, by varying the proportion of broken kernels in milled rice. © 2012 Society of Chemical Industry.

Effect of particle size and dopant concentration on photophysical properties of Eu3+-doped rare earth oxysulphide phosphor coatings.

PubMed

Chakradhar, R P S; Basu, Bharathibai J; Lakshmi, R V

2011-02-01

Europium-doped rare-earth oxysulphides (red phosphors) are often used as reference luminophore in pyrene-based pressure sensor coatings for aerodynamic applications. Different red phosphor samples were characterized for their particle size, chemical composition, photoluminescent properties and temperature sensitivity. The red phosphor samples were characterized using energy-dispersive X-ray spectroscopy (EDX) for elemental analysis and scanning electron microscopy (SEM) for morphology and particle size measurement. The particle size was in the range of 1.5-5.7 μm with morphology of hexagonal or spherical shape. It was found that phosphor with higher europium content exhibited higher luminescent emission intensity. The phosphor coatings were prepared by spraying a dispersion of the material in silicone resin. Smooth coatings were obtained by using phosphor samples with smaller particle size. Upon 334 nm excitation, the coatings showed characteristic luminescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 626 nm (5D0→7F2) of Eu3+ ions was stronger than the magnetic dipole transition located at 595 nm (5D0→7F1). Luminescence decay curves obeyed double exponential behaviour. The phosphor samples showed temperature sensitivity of -0.012 to -0.168%/°C in the temperature range of 25-50 °C. Copyright © 2010 Elsevier B.V. All rights reserved.

Development and optimization of enteric coated mucoadhesive microspheres of duloxetine hydrochloride using 3(2) full factorial design.

PubMed

Setia, Anupama; Kansal, Sahil; Goyal, Naveen

2013-07-01

Microspheres constitute an important part of oral drug delivery system by virtue of their small size and efficient carrier capacity. However, the success of these microspheres is limited due to their short residence time at the site of absorption. The objective of the present study was to formulate and systematically evaluate in vitro performance of enteric coated mucoadhesive microspheres of duloxetine hydrochloride (DLX), an acid labile drug. DLX microspheres were prepared by simple emulsification phase separation technique using chitosan as carrier and glutaraldehyde as a cross-linking agent. Microspheres prepared were coated with eudragit L-100 using an oil-in-oil solvent evaporation method. Eudragit L-100was used as enteric coating polymer with the aim to release the drug in small intestine The microspheres prepared were characterized by particle size, entrapment efficiency, swelling index (SI), mucoadhesion time, in vitro drug release and surface morphology. A 3(2) full factorial design was employed to study the effect of independent variables polymer-to-drug ratio (X1) and stirring speed (X2) on dependent variables, particle size, entrapment efficiency, SI, in vitro mucoadhesion and drug release up to 24 h (t24). Microspheres formed were discrete, spherical and free flowing. The microspheres exhibited good mucoadhesive property and also showed high percentage entrapment efficiency. The microspheres were able to sustain the drug release up to 24 h. Thus, the prepared enteric coated mucoadhesive microspheres may prove to be a potential controlled release formulation of DLX for oral administration.

Fabrication and characterization of DLC coated microdimples on hip prosthesis heads.

PubMed

Choudhury, Dipankar; Ay Ching, Hee; Mamat, Azuddin Bin; Cizek, Jan; Abu Osman, Noor Azuan; Vrbka, Martin; Hartl, Martin; Krupka, Ivan

2015-07-01

Diamond like carbon (DLC) is applied as a thin film onto substrates to obtain desired surface properties such as increased hardness and corrosion resistance, and decreased friction and wear rate. Microdimple is an advanced surface modification technique enhancing the tribological performance. In this study, DLC coated microdimples were fabricated on hip prosthesis heads and their mechanical, material and surface properties were characterized. An Electro discharge machining (EDM) oriented microdrilling was utilized to fabricate a defined microdimple array (diameter of 300 µm, depth of 70 µm, and pitch of 900 µm) on stainless steel (SS) hip prosthesis heads. The dimpled surfaces were then coated by hydrogenated amorphous carbon (a-C:H) and tetrahedral amorphous carbon (Ta-C) layers by using a magnetron sputtering technology. A preliminary tribology test was conducted on these fabricated surfaces against a ceramic ball in simulated hip joint conditions. It was found that the fabricated dimples were perpendicular to the spherical surfaces and no cutting-tools wear debris was detected inside the individual dimples. The a-C:H and Ta-C coatings increased the hardness at both the dimple edges and the nondimpled region. The tribology test showed a significant reduction in friction coefficient for coated surfaces regardless of microdimple arrays: the lowest friction coefficient was found for the a-C:H samples (µ = 0.084), followed by Ta-C (µ = 0.119), as compared to the SS surface (µ = 0.248). © 2014 Wiley Periodicals, Inc.

Synthesis of SiO2-Coated Core-Shell ZnO Composites for Preparing High-Voltage Varistors

NASA Astrophysics Data System (ADS)

Qu, Xiao; Yao, Da-Chuan; Liu, Jin-Ran; Wang, Mao-Hua; Zhang, Han-Ping

2018-01-01

Monodispersed ZnO composite microspheres were successfully prepared by a facile ultrasound irradiation method. Then, the uniform core-shell structured composites were synthesized through the hydrolysis of tetraethyl orthosilicate on the surface of the ZnO composite microspheres. Microstructural studies of the as-obtained powders were carried out using the techniques of the x-ray powder diffraction, field emission scanning electron microscopy and transmission electron microscopy with energy dispersive x-ray spectroscopy. The results show that the pink ZnO composite powders as the core were spherical structures with the size of approximately 100 nm, and the SiO2 shell was fully coated on the surface of the core. On the basis of these results, the effect of SiO2 content on the thickness of the synthesized composites and microstructure, as well as the electrical properties of the ZnO varistors sintered in air at 1150°C for 2 h, were fully studied. In particular, the ZnO varistor prepared with the appropriate amount of the SiO2 coating (˜40 nm) leads to a superior electrical performance with the high breakdown voltage of 418 V mm-1 and an excellent nonlinear coefficient of 70.7, compared with the varistors obtained without the SiO2 coating. The high performance is attributed to the smaller and more homogeneous ZnO grains obtained via the SiO2 coating.

Nonlinear Deep Kernel Learning for Image Annotation.

PubMed

Jiu, Mingyuan; Sahbi, Hichem

2017-02-08

Multiple kernel learning (MKL) is a widely used technique for kernel design. Its principle consists in learning, for a given support vector classifier, the most suitable convex (or sparse) linear combination of standard elementary kernels. However, these combinations are shallow and often powerless to capture the actual similarity between highly semantic data, especially for challenging classification tasks such as image annotation. In this paper, we redefine multiple kernels using deep multi-layer networks. In this new contribution, a deep multiple kernel is recursively defined as a multi-layered combination of nonlinear activation functions, each one involves a combination of several elementary or intermediate kernels, and results into a positive semi-definite deep kernel. We propose four different frameworks in order to learn the weights of these networks: supervised, unsupervised, kernel-based semisupervised and Laplacian-based semi-supervised. When plugged into support vector machines (SVMs), the resulting deep kernel networks show clear gain, compared to several shallow kernels for the task of image annotation. Extensive experiments and analysis on the challenging ImageCLEF photo annotation benchmark, the COREL5k database and the Banana dataset validate the effectiveness of the proposed method.

Multineuron spike train analysis with R-convolution linear combination kernel.

PubMed

Tezuka, Taro

2018-06-01

A spike train kernel provides an effective way of decoding information represented by a spike train. Some spike train kernels have been extended to multineuron spike trains, which are simultaneously recorded spike trains obtained from multiple neurons. However, most of these multineuron extensions were carried out in a kernel-specific manner. In this paper, a general framework is proposed for extending any single-neuron spike train kernel to multineuron spike trains, based on the R-convolution kernel. Special subclasses of the proposed R-convolution linear combination kernel are explored. These subclasses have a smaller number of parameters and make optimization tractable when the size of data is limited. The proposed kernel was evaluated using Gaussian process regression for multineuron spike trains recorded from an animal brain. It was compared with the sum kernel and the population Spikernel, which are existing ways of decoding multineuron spike trains using kernels. The results showed that the proposed approach performs better than these kernels and also other commonly used neural decoding methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study on Energy Productivity Ratio (EPR) at palm kernel oil processing factory: case study on PT-X at Sumatera Utara Plantation

NASA Astrophysics Data System (ADS)

Haryanto, B.; Bukit, R. Br; Situmeang, E. M.; Christina, E. P.; Pandiangan, F.

2018-02-01

The purpose of this study was to determine the performance, productivity and feasibility of the operation of palm kernel processing plant based on Energy Productivity Ratio (EPR). EPR is expressed as the ratio of output to input energy and by-product. Palm Kernel plan is process in palm kernel to become palm kernel oil. The procedure started from collecting data needed as energy input such as: palm kernel prices, energy demand and depreciation of the factory. The energy output and its by-product comprise the whole production price such as: palm kernel oil price and the remaining products such as shells and pulp price. Calculation the equality of energy of palm kernel oil is to analyze the value of Energy Productivity Ratio (EPR) bases on processing capacity per year. The investigation has been done in Kernel Oil Processing Plant PT-X at Sumatera Utara plantation. The value of EPR was 1.54 (EPR > 1), which indicated that the processing of palm kernel into palm kernel oil is feasible to be operated based on the energy productivity.

Fabrication of Spherical Reflectors in Outer Space

NASA Technical Reports Server (NTRS)

Wang, Yu; Dooley, Jennifer; Dragovan, Mark; Serivens, Wally

2005-01-01

A process is proposed for fabrication of lightweight spherical reflectors in outer space for telescopes, radio antennas, and light collectors that would be operated there. The process would obviate the relatively massive substrates and frames needed to support such reflectors in normal Earth gravitation. According to the proposal, fabrication of a reflector would begin with blowing of a bubble to the specified reflector radius. Taking advantage of the outer-space vacuum as a suitable environment for evaporative deposition of metal, a metal-evaporation source would be turned on and moved around the bubble to deposit a reflective metal film over the specified reflector area to a thickness of several microns. Then the source would be moved and aimed to deposit more metal around the edge of the reflector area, increasing the thickness there to approximately equal to 100 micron to form a frame. Then the bubble would be deflated and peeled off the metal, leaving a thin-film spherical mirror having an integral frame. The mirror would then be mounted for use. The feasibility of this technology has been proved by fabricating a prototype at JPL. As shown in the figure, a 2-in. (.5-cm) diameter hemispherical prototype reflector was made from a polymer bubble coated with silver, forming a very smooth surface.

Observations and Modeling of the Green Ocean Amazon 2014/15: Transmission Electron Microscopy Analysis of Aerosol Particles Field Campaign Report

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

Buseck, Peter

2016-03-01

During two Intensive Operational Periods (IOP), we collected samples at 3-hour intervals for transmission electron microscopy analysis. The resulting transmission electron microscopy images and compositions were analyzed for the samples of interest. Further analysis will be done especially for the plume of interest. We found solid spherical organic particles from rebounded samples collected with Professor Scot Martin’s group (Harvard University). Approximately 30% of the rebounded particles at 95% relative humidity were spherical organic particles. Their sources and formation process are not known, but such spherical particles could be solid and will have heterogeneous chemical reactions. We observed many organic particlesmore » that are internally mixed with inorganic elements such as potassium and nitrogen. They are either homogeneously mixed or have inorganic cores with organic aerosol coatings. Samples collected from the Manaus, Brazil, pollution plume included many nano-size soot particles mixed with organic material and sulfate. Aerosol particles from clean periods included organic aerosol particles, sulfate, sea salt, dust, and primary biogenic aerosol particles. There was more dust, primary biogenic aerosol, and tar balls in samples taken during IOP1 than those taken during IOP2. Many dust particles were found between March 2 and 3.« less

Predicting complex traits using a diffusion kernel on genetic markers with an application to dairy cattle and wheat data

PubMed Central

2013-01-01

Background Arguably, genotypes and phenotypes may be linked in functional forms that are not well addressed by the linear additive models that are standard in quantitative genetics. Therefore, developing statistical learning models for predicting phenotypic values from all available molecular information that are capable of capturing complex genetic network architectures is of great importance. Bayesian kernel ridge regression is a non-parametric prediction model proposed for this purpose. Its essence is to create a spatial distance-based relationship matrix called a kernel. Although the set of all single nucleotide polymorphism genotype configurations on which a model is built is finite, past research has mainly used a Gaussian kernel. Results We sought to investigate the performance of a diffusion kernel, which was specifically developed to model discrete marker inputs, using Holstein cattle and wheat data. This kernel can be viewed as a discretization of the Gaussian kernel. The predictive ability of the diffusion kernel was similar to that of non-spatial distance-based additive genomic relationship kernels in the Holstein data, but outperformed the latter in the wheat data. However, the difference in performance between the diffusion and Gaussian kernels was negligible. Conclusions It is concluded that the ability of a diffusion kernel to capture the total genetic variance is not better than that of a Gaussian kernel, at least for these data. Although the diffusion kernel as a choice of basis function may have potential for use in whole-genome prediction, our results imply that embedding genetic markers into a non-Euclidean metric space has very small impact on prediction. Our results suggest that use of the black box Gaussian kernel is justified, given its connection to the diffusion kernel and its similar predictive performance. PMID:23763755

Rose bengal-grafted biodegradable microcapsules: singlet-oxygen generation and cancer-cell incapacitation.

PubMed

Wang, Xiao-Lei; Zeng, Yu; Zheng, Yan-Zhen; Chen, Jian-Feng; Tao, Xia; Wang, Ling-Xuan; Teng, Yan

2011-09-26

Rose bengal-grafted chitosan (RB-CHI), synthesized through dehydration between amino and carboxyl functional groups under mild conditions, was coated onto the outer layer of preformed biodegradable microcapsules consisting of sodium alginate and chitosan. The fabricated photosensitive microcapsules were characterized by optical microscopy, scanning electron microscopy, and confocal laser scanning microscopy. The assembled materials maintained intact spherical morphology and thus showed good ability to form thin films. Electron spin resonance spectroscopy allowed direct observation of the generation of singlet oxygen ((1)O(2)) from photosensitive microcapsules under light excitation at about 545 nm. Furthermore, with increasing light radiation, the content of (1)O(2) increased, as detected by a chemical probe. In vitro cellular toxicity assays showed that RB-CHI-coated photosensitive microcapsules exhibit good biocompatibility in darkness and high cytotoxicity after irradiation, and could provide new photoresponsive drug-delivery vehicles. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and analysis of a fast, two-mirror soft-x-ray microscope

NASA Technical Reports Server (NTRS)

Shealy, D. L.; Wang, C.; Jiang, W.; Jin, L.; Hoover, R. B.

1992-01-01

During the past several years, a number of investigators have addressed the design, analysis, fabrication, and testing of spherical Schwarzschild microscopes for soft-x-ray applications using multilayer coatings. Some of these systems have demonstrated diffraction limited resolution for small numerical apertures. Rigorously aplanatic, two-aspherical mirror Head microscopes can provide near diffraction limited resolution for very large numerical apertures. The relationships between the numerical aperture, mirror radii and diameters, magnifications, and total system length for Schwarzschild microscope configurations are summarized. Also, an analysis of the characteristics of the Head-Schwarzschild surfaces will be reported. The numerical surface data predicted by the Head equations were fit by a variety of functions and analyzed by conventional optical design codes. Efforts have been made to determine whether current optical substrate and multilayer coating technologies will permit construction of a very fast Head microscope which can provide resolution approaching that of the wavelength of the incident radiation.

Superparamagnetism in carbon-coated Co particles produced by the Kratschmer carbon arc process

NASA Astrophysics Data System (ADS)

McHenry, M. E.; Majetich, S. A.; Artman, J. O.; Degraef, M.; Staley, S. W.

1994-04-01

A process based on the Kratschmer-Huffman carbon arc method of preparing fullerenes has been used to generate carbon-coated cobalt and cobalt carbide nanocrystallites. Magnetic nanocrystallites are extracted from the soot with a gradient field technique. For Co/C composites, structural characterization by x-ray diffraction and high-resolution transmission electron microscopy reveals the presence of a fcc Co phase, graphite, and a minority Co2C phase. The majority of Co nanocrystals exists as nominally spherical particles, 0.5-5 nm in radius. Hysteretic and temperature-dependent magnetic response, in randomly and magnetically aligned powder samples frozen in epoxy reveals fine-particle magnetism associated with monodomain Co particles. The magnetization exhibits a unique functional dependence on H/T, and hysteresis below a blocking temperature, TB~=160 K. Below TB, the temperature dependence of the coercivity is given by Hc=Hci[1-(T/TB)1/2], with Hci~=450 Oe.

A moderate method for preparation DMSA coated Fe3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Song, L. N.; Gu, N.; Zhang, Y.

2017-01-01

A moderate way to prepare water soluble magnetic Fe3O4 nanoparticles has been developed. Firstly, oleic acid coated Fe3O4 is prepared by coprecipitation. Second, oleic acid were replaced by 2,3-dimercaptosuccinnic acid (DMSA) to prepare DMSA/Fe3O4 in the mixed solution of n-hexane and acetone. After dialysis and filtration the DMSA/Fe3O4 can be transferred into distilled water to form stable Fe3O4 nanoparticle solutions. The TEM images indicated that the particles had spherical shape and the nanoparticles were found to be 12 nm with a relatively narrow size distribution with the hydrodynamic size of 30 nm. And the result of VSM shows that DMSA/Fe3O4 nanoparticles have a saturation magnetization of 31 emu/g. The IR spectra indicated that the iron oxide was located by carboxyl matrix.

Fabrication of lactobionic-loaded chitosan microcapsules as potential drug carriers targeting the liver.

PubMed

Zhang, Jing; Li, Cao; Xue, Zhi-Yuan; Cheng, Hai-Wei; Huang, Fu-Wei; Zhuo, Ren-Xi; Zhang, Xian-Zheng

2011-04-01

This paper demonstrates a general approach for fabrication of lactobionic chitosan microcapsules using layer-by-layer assembly via click chemistry. Chitosan was selectively modified with either azide (CHI-Az) or alkyne (CHI-Alk) groups. The growth of the CHI-Az/CHI-Alk click multilayer was studied experimentally by multilayer assembly on planar supports. Linear buildup of the film was observed. The chitosan click capsules were also analyzed with confocal laser scanning microscopy and transmission electron microscopy. Capsules were found to have regular spherical shapes. In addition, (CHI-Az/CHI-Alk)-coated particles were modified with fluorescein isothiocyanate to ensure that the particles can be easily post-functionalized. Finally, lactobionic acid was conjugated onto the (CHI-Az/CHI-Alk)-coated particles and the lactobionic particles exhibited hepatoma cell (HepG2) targeting behavior. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Variables separation of the spectral BRDF for better understanding color variation in special effect pigment coatings.

PubMed

Ferrero, Alejandro; Rabal, Ana María; Campos, Joaquín; Pons, Alicia; Hernanz, María Luisa

2012-06-01

A type of representation of the spectral bidirectional reflectance distribution function (BRDF) is proposed that distinctly separates the spectral variable (wavelength) from the geometrical variables (spherical coordinates of the irradiation and viewing directions). Principal components analysis (PCA) is used in order to decompose the spectral BRDF in decorrelated spectral components, and the weight that they have at every geometrical configuration of irradiation/viewing is established. This method was applied to the spectral BRDF measurement of a special effect pigment sample, and four principal components with relevant variance were identified. These four components are enough to reproduce the great diversity of spectral reflectances observed at different geometrical configurations. Since this representation is able to separate spectral and geometrical variables, it facilitates the interpretation of the color variation of special effect pigments coatings versus the geometrical configuration of irradiation/viewing.

WE-EF-207-01: FEATURED PRESENTATION and BEST IN PHYSICS (IMAGING): Task-Driven Imaging for Cone-Beam CT in Interventional Guidance

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

Gang, G; Stayman, J; Ouadah, S

2015-06-15

Purpose: This work introduces a task-driven imaging framework that utilizes a patient-specific anatomical model, mathematical definition of the imaging task, and a model of the imaging system to prospectively design acquisition and reconstruction techniques that maximize task-based imaging performance. Utility of the framework is demonstrated in the joint optimization of tube current modulation and view-dependent reconstruction kernel in filtered-backprojection reconstruction and non-circular orbit design in model-based reconstruction. Methods: The system model is based on a cascaded systems analysis of cone-beam CT capable of predicting the spatially varying noise and resolution characteristics as a function of the anatomical model and amore » wide range of imaging parameters. Detectability index for a non-prewhitening observer model is used as the objective function in a task-driven optimization. The combination of tube current and reconstruction kernel modulation profiles were identified through an alternating optimization algorithm where tube current was updated analytically followed by a gradient-based optimization of reconstruction kernel. The non-circular orbit is first parameterized as a linear combination of bases functions and the coefficients were then optimized using an evolutionary algorithm. The task-driven strategy was compared with conventional acquisitions without modulation, using automatic exposure control, and in a circular orbit. Results: The task-driven strategy outperformed conventional techniques in all tasks investigated, improving the detectability of a spherical lesion detection task by an average of 50% in the interior of a pelvis phantom. The non-circular orbit design successfully mitigated photon starvation effects arising from a dense embolization coil in a head phantom, improving the conspicuity of an intracranial hemorrhage proximal to the coil. Conclusion: The task-driven imaging framework leverages a knowledge of the imaging task within a patient-specific anatomical model to optimize image acquisition and reconstruction techniques, thereby improving imaging performance beyond that achievable with conventional approaches. 2R01-CA-112163; R01-EB-017226; U01-EB-018758; Siemens Healthcare (Forcheim, Germany)« less

7 CFR 981.9 - Kernel weight.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Kernel weight. 981.9 Section 981.9 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements... Regulating Handling Definitions § 981.9 Kernel weight. Kernel weight means the weight of kernels, including...

An SVM model with hybrid kernels for hydrological time series

NASA Astrophysics Data System (ADS)

Wang, C.; Wang, H.; Zhao, X.; Xie, Q.

2017-12-01

Support Vector Machine (SVM) models have been widely applied to the forecast of climate/weather and its impact on other environmental variables such as hydrologic response to climate/weather. When using SVM, the choice of the kernel function plays the key role. Conventional SVM models mostly use one single type of kernel function, e.g., radial basis kernel function. Provided that there are several featured kernel functions available, each having its own advantages and drawbacks, a combination of these kernel functions may give more flexibility and robustness to SVM approach, making it suitable for a wide range of application scenarios. This paper presents such a linear combination of radial basis kernel and polynomial kernel for the forecast of monthly flowrate in two gaging stations using SVM approach. The results indicate significant improvement in the accuracy of predicted series compared to the approach with either individual kernel function, thus demonstrating the feasibility and advantages of such hybrid kernel approach for SVM applications.

Approximate kernel competitive learning.

PubMed

Wu, Jian-Sheng; Zheng, Wei-Shi; Lai, Jian-Huang

2015-03-01

Kernel competitive learning has been successfully used to achieve robust clustering. However, kernel competitive learning (KCL) is not scalable for large scale data processing, because (1) it has to calculate and store the full kernel matrix that is too large to be calculated and kept in the memory and (2) it cannot be computed in parallel. In this paper we develop a framework of approximate kernel competitive learning for processing large scale dataset. The proposed framework consists of two parts. First, it derives an approximate kernel competitive learning (AKCL), which learns kernel competitive learning in a subspace via sampling. We provide solid theoretical analysis on why the proposed approximation modelling would work for kernel competitive learning, and furthermore, we show that the computational complexity of AKCL is largely reduced. Second, we propose a pseudo-parallelled approximate kernel competitive learning (PAKCL) based on a set-based kernel competitive learning strategy, which overcomes the obstacle of using parallel programming in kernel competitive learning and significantly accelerates the approximate kernel competitive learning for large scale clustering. The empirical evaluation on publicly available datasets shows that the proposed AKCL and PAKCL can perform comparably as KCL, with a large reduction on computational cost. Also, the proposed methods achieve more effective clustering performance in terms of clustering precision against related approximate clustering approaches. Copyright © 2014 Elsevier Ltd. All rights reserved.

Multiple kernels learning-based biological entity relationship extraction method.

PubMed

Dongliang, Xu; Jingchang, Pan; Bailing, Wang

2017-09-20

Automatic extracting protein entity interaction information from biomedical literature can help to build protein relation network and design new drugs. There are more than 20 million literature abstracts included in MEDLINE, which is the most authoritative textual database in the field of biomedicine, and follow an exponential growth over time. This frantic expansion of the biomedical literature can often be difficult to absorb or manually analyze. Thus efficient and automated search engines are necessary to efficiently explore the biomedical literature using text mining techniques. The P, R, and F value of tag graph method in Aimed corpus are 50.82, 69.76, and 58.61%, respectively. The P, R, and F value of tag graph kernel method in other four evaluation corpuses are 2-5% higher than that of all-paths graph kernel. And The P, R and F value of feature kernel and tag graph kernel fuse methods is 53.43, 71.62 and 61.30%, respectively. The P, R and F value of feature kernel and tag graph kernel fuse methods is 55.47, 70.29 and 60.37%, respectively. It indicated that the performance of the two kinds of kernel fusion methods is better than that of simple kernel. In comparison with the all-paths graph kernel method, the tag graph kernel method is superior in terms of overall performance. Experiments show that the performance of the multi-kernels method is better than that of the three separate single-kernel method and the dual-mutually fused kernel method used hereof in five corpus sets.

7 CFR 51.2295 - Half kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Half kernel. 51.2295 Section 51.2295 Agriculture... Standards for Shelled English Walnuts (Juglans Regia) Definitions § 51.2295 Half kernel. Half kernel means the separated half of a kernel with not more than one-eighth broken off. ...

7 CFR 810.206 - Grades and grade requirements for barley.

Code of Federal Regulations, 2010 CFR

2010-01-01

... weight per bushel (pounds) Sound barley (percent) Maximum Limits of— Damaged kernels 1 (percent) Heat damaged kernels (percent) Foreign material (percent) Broken kernels (percent) Thin barley (percent) U.S... or otherwise of distinctly low quality. 1 Includes heat-damaged kernels. Injured-by-frost kernels and...

ϕX174 Procapsid Assembly: Effects of an Inhibitory External Scaffolding Protein and Resistant Coat Proteins In Vitro.

PubMed

Cherwa, James E; Tyson, Joshua; Bedwell, Gregory J; Brooke, Dewey; Edwards, Ashton G; Dokland, Terje; Prevelige, Peter E; Fane, Bentley A

2017-01-01

During ϕX174 morphogenesis, 240 copies of the external scaffolding protein D organize 12 pentameric assembly intermediates into procapsids, a reaction reconstituted in vitro In previous studies, ϕX174 strains resistant to exogenously expressed dominant lethal D genes were experimentally evolved. Resistance was achieved by the stepwise acquisition of coat protein mutations. Once resistance was established, a stimulatory D protein mutation that greatly increased strain fitness arose. In this study, in vitro biophysical and biochemical methods were utilized to elucidate the mechanistic details and evolutionary trade-offs created by the resistance mutations. The kinetics of procapsid formation was analyzed in vitro using wild-type, inhibitory, and experimentally evolved coat and scaffolding proteins. Our data suggest that viral fitness is correlated with in vitro assembly kinetics and demonstrate that in vivo experimental evolution can be analyzed within an in vitro biophysical context. Experimental evolution is an extremely valuable tool. Comparisons between ancestral and evolved genotypes suggest hypotheses regarding adaptive mechanisms. However, it is not always possible to rigorously test these hypotheses in vivo We applied in vitro biophysical and biochemical methods to elucidate the mechanistic details that allowed an experimentally evolved virus to become resistant to an antiviral protein and then evolve a productive use for that protein. Moreover, our results indicate that the respective roles of scaffolding and coat proteins may have been redistributed during the evolution of a two-scaffolding-protein system. In one-scaffolding-protein virus assembly systems, coat proteins promiscuously interact to form heterogeneous aberrant structures in the absence of scaffolding proteins. Thus, the scaffolding protein controls fidelity. During ϕX174 assembly, the external scaffolding protein acts like a coat protein, self-associating into large aberrant spherical structures in the absence of coat protein, whereas the coat protein appears to control fidelity. Copyright © 2016 American Society for Microbiology.

Surface-engineered core-shell nano-size ferrites and their antimicrobial activity

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

Baraliya, Jagdish D., E-mail: jdbaraliya@yahoo.co.in; Joshi, Hiren H., E-mail: jdbaraliya@yahoo.co.in

We report the results of biological study on core-shell structured MFe{sub 2}O{sub 4} (where M = Co, Mn, Ni) nanoparticles and influence of silica- DEG dual coating on their antimicrobial activity. Spherical MFe{sub 2}O{sub 4} nanoparticles were prepared via a Co-precipitation method. The microstructures and morphologies of these nanoparticles were studied by x-ray diffraction and FTIR. The antimicrobial activity study carried out in nutrient agar medium with addition of antimicrobial synthesis compound which is tested for its activity against different types of bacteria.

Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

PubMed

García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

2009-09-17

Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu(3+) doped BaTiO(3).

Surface-engineered core-shell nano-size ferrites and their antimicrobial activity

NASA Astrophysics Data System (ADS)

Baraliya, Jagdish D.; Joshi, Hiren H.

2014-04-01

We report the results of biological study on core-shell structured MFe2O4 (where M = Co, Mn, Ni) nanoparticles and influence of silica- DEG dual coating on their antimicrobial activity. Spherical MFe2O4 nanoparticles were prepared via a Co-precipitation method. The microstructures and morphologies of these nanoparticles were studied by x-ray diffraction and FTIR. The antimicrobial activity study carried out in nutrient agar medium with addition of antimicrobial synthesis compound which is tested for its activity against different types of bacteria.

7 CFR 51.1449 - Damage.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Kernel which is “dark amber” or darker color; (e) Kernel having more than one dark kernel spot, or one dark kernel spot more than one-eighth inch in greatest dimension; (f) Shriveling when the surface of the kernel is very conspicuously wrinkled; (g) Internal flesh discoloration of a medium shade of gray...

7 CFR 51.1449 - Damage.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Kernel which is “dark amber” or darker color; (e) Kernel having more than one dark kernel spot, or one dark kernel spot more than one-eighth inch in greatest dimension; (f) Shriveling when the surface of the kernel is very conspicuously wrinkled; (g) Internal flesh discoloration of a medium shade of gray...

7 CFR 51.2125 - Split or broken kernels.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Split or broken kernels. 51.2125 Section 51.2125 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... kernels. Split or broken kernels means seven-eighths or less of complete whole kernels but which will not...

7 CFR 51.2296 - Three-fourths half kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Three-fourths half kernel. 51.2296 Section 51.2296 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards...-fourths half kernel. Three-fourths half kernel means a portion of a half of a kernel which has more than...

The Classification of Diabetes Mellitus Using Kernel k-means

NASA Astrophysics Data System (ADS)

Alamsyah, M.; Nafisah, Z.; Prayitno, E.; Afida, A. M.; Imah, E. M.

2018-01-01

Diabetes Mellitus is a metabolic disorder which is characterized by chronicle hypertensive glucose. Automatics detection of diabetes mellitus is still challenging. This study detected diabetes mellitus by using kernel k-Means algorithm. Kernel k-means is an algorithm which was developed from k-means algorithm. Kernel k-means used kernel learning that is able to handle non linear separable data; where it differs with a common k-means. The performance of kernel k-means in detecting diabetes mellitus is also compared with SOM algorithms. The experiment result shows that kernel k-means has good performance and a way much better than SOM.

UNICOS Kernel Internals Application Development

NASA Technical Reports Server (NTRS)

Caredo, Nicholas; Craw, James M. (Technical Monitor)

1995-01-01

Having an understanding of UNICOS Kernel Internals is valuable information. However, having the knowledge is only half the value. The second half comes with knowing how to use this information and apply it to the development of tools. The kernel contains vast amounts of useful information that can be utilized. This paper discusses the intricacies of developing utilities that utilize kernel information. In addition, algorithms, logic, and code will be discussed for accessing kernel information. Code segments will be provided that demonstrate how to locate and read kernel structures. Types of applications that can utilize kernel information will also be discussed.

Detection of maize kernels breakage rate based on K-means clustering

NASA Astrophysics Data System (ADS)

Yang, Liang; Wang, Zhuo; Gao, Lei; Bai, Xiaoping

2017-04-01

In order to optimize the recognition accuracy of maize kernels breakage detection and improve the detection efficiency of maize kernels breakage, this paper using computer vision technology and detecting of the maize kernels breakage based on K-means clustering algorithm. First, the collected RGB images are converted into Lab images, then the original images clarity evaluation are evaluated by the energy function of Sobel 8 gradient. Finally, the detection of maize kernels breakage using different pixel acquisition equipments and different shooting angles. In this paper, the broken maize kernels are identified by the color difference between integrity kernels and broken kernels. The original images clarity evaluation and different shooting angles are taken to verify that the clarity and shooting angles of the images have a direct influence on the feature extraction. The results show that K-means clustering algorithm can distinguish the broken maize kernels effectively.

Modeling adaptive kernels from probabilistic phylogenetic trees.

PubMed

Nicotra, Luca; Micheli, Alessio

2009-01-01

Modeling phylogenetic interactions is an open issue in many computational biology problems. In the context of gene function prediction we introduce a class of kernels for structured data leveraging on a hierarchical probabilistic modeling of phylogeny among species. We derive three kernels belonging to this setting: a sufficient statistics kernel, a Fisher kernel, and a probability product kernel. The new kernels are used in the context of support vector machine learning. The kernels adaptivity is obtained through the estimation of the parameters of a tree structured model of evolution using as observed data phylogenetic profiles encoding the presence or absence of specific genes in a set of fully sequenced genomes. We report results obtained in the prediction of the functional class of the proteins of the budding yeast Saccharomyces cerevisae which favorably compare to a standard vector based kernel and to a non-adaptive tree kernel function. A further comparative analysis is performed in order to assess the impact of the different components of the proposed approach. We show that the key features of the proposed kernels are the adaptivity to the input domain and the ability to deal with structured data interpreted through a graphical model representation.

Aflatoxin and nutrient contents of peanut collected from local market and their processed foods

NASA Astrophysics Data System (ADS)

Ginting, E.; Rahmianna, A. A.; Yusnawan, E.

2018-01-01

Peanut is succeptable to aflatoxin contamination and the sources of peanut as well as processing methods considerably affect aflatoxin content of the products. Therefore, the study on aflatoxin and nutrient contents of peanut collected from local market and their processed foods were performed. Good kernels of peanut were prepared into fried peanut, pressed-fried peanut, peanut sauce, peanut press cake, fermented peanut press cake (tempe) and fried tempe, while blended kernels (good and poor kernels) were processed into peanut sauce and tempe and poor kernels were only processed into tempe. The results showed that good and blended kernels which had high number of sound/intact kernels (82,46% and 62,09%), contained 9.8-9.9 ppb of aflatoxin B1, while slightly higher level was seen in poor kernels (12.1 ppb). However, the moisture, ash, protein, and fat contents of the kernels were similar as well as the products. Peanut tempe and fried tempe showed the highest increase in protein content, while decreased fat contents were seen in all products. The increase in aflatoxin B1 of peanut tempe prepared from poor kernels > blended kernels > good kernels. However, it averagely decreased by 61.2% after deep-fried. Excluding peanut tempe and fried tempe, aflatoxin B1 levels in all products derived from good kernels were below the permitted level (15 ppb). This suggests that sorting peanut kernels as ingredients and followed by heat processing would decrease the aflatoxin content in the products.

Partial Deconvolution with Inaccurate Blur Kernel.

PubMed

Ren, Dongwei; Zuo, Wangmeng; Zhang, David; Xu, Jun; Zhang, Lei

2017-10-17

Most non-blind deconvolution methods are developed under the error-free kernel assumption, and are not robust to inaccurate blur kernel. Unfortunately, despite the great progress in blind deconvolution, estimation error remains inevitable during blur kernel estimation. Consequently, severe artifacts such as ringing effects and distortions are likely to be introduced in the non-blind deconvolution stage. In this paper, we tackle this issue by suggesting: (i) a partial map in the Fourier domain for modeling kernel estimation error, and (ii) a partial deconvolution model for robust deblurring with inaccurate blur kernel. The partial map is constructed by detecting the reliable Fourier entries of estimated blur kernel. And partial deconvolution is applied to wavelet-based and learning-based models to suppress the adverse effect of kernel estimation error. Furthermore, an E-M algorithm is developed for estimating the partial map and recovering the latent sharp image alternatively. Experimental results show that our partial deconvolution model is effective in relieving artifacts caused by inaccurate blur kernel, and can achieve favorable deblurring quality on synthetic and real blurry images.Most non-blind deconvolution methods are developed under the error-free kernel assumption, and are not robust to inaccurate blur kernel. Unfortunately, despite the great progress in blind deconvolution, estimation error remains inevitable during blur kernel estimation. Consequently, severe artifacts such as ringing effects and distortions are likely to be introduced in the non-blind deconvolution stage. In this paper, we tackle this issue by suggesting: (i) a partial map in the Fourier domain for modeling kernel estimation error, and (ii) a partial deconvolution model for robust deblurring with inaccurate blur kernel. The partial map is constructed by detecting the reliable Fourier entries of estimated blur kernel. And partial deconvolution is applied to wavelet-based and learning-based models to suppress the adverse effect of kernel estimation error. Furthermore, an E-M algorithm is developed for estimating the partial map and recovering the latent sharp image alternatively. Experimental results show that our partial deconvolution model is effective in relieving artifacts caused by inaccurate blur kernel, and can achieve favorable deblurring quality on synthetic and real blurry images.

The single scattering properties of soot aggregates with concentric core-shell spherical monomers

NASA Astrophysics Data System (ADS)

Wu, Yu; Cheng, Tianhai; Gu, Xingfa; Zheng, Lijuan; Chen, Hao; Xu, Hui

2014-03-01

Anthropogenic soot aerosols are shown as complex, fractal-like aggregated structures with high light absorption efficiency. In atmospheric environment, soot monomers may tend to acquire a weakly absorbing coating, such as an organic coating, which introduces further complexity to the optical properties of the aggregates. The single scattering properties of soot aggregates can be significantly influenced by the coated status of these kinds of aerosols. In this article, the monomers of fractal soot aggregates are modelled as semi-external mixtures (physical contact) with constant radius of soot core and variable sizes of the coating for specific soot volume fractions. The single scattering properties of these coated soot particles, such as phase function, the cross sections of extinction and absorption, single scattering albedo (SSA) and asymmetry parameter (ASY), are calculated using the numerically exact superposition T-matrix method. The random-orientation averaging results have shown that the single scattering properties of these coated soot aggregates are significantly different from the single volume-equivalent core-shell sphere approximation using the Mie theory and the homogeneous aggregates with uncoated monomers using the effective medium theory, such as Maxwell-Garnett and Bruggemann approximations, which overestimate backscattering of coated soot. It is found that the SSA and cross sections of extinction and absorption are increased for soot aggregates with thicker weakly absorbing coating on the monomers. Especially, the SSA values of these simulated aggregates with less soot core volume fractions are remarkably (~50% for core volume fraction of soot aggregates of 0.5, ~100% for a core volume fraction of 0.2, at 0.67 μm) larger than for uncoated soot particles without consideration of coating. Moreover, the cross sections of extinction and absorption are underestimated by the computation of equivalent homogeneous fractal aggregate approximation (within 5% for the T-matrix method and 10-25% for the Rayleigh-Debye-Gans approximation due to different soot volume fractions). Further understanding of the optical properties of these coated soot aggregates would be helpful for both environment monitoring and climate studies.

Mathematics of Computed Tomography

NASA Astrophysics Data System (ADS)

Hawkins, William Grant

A review of the applications of the Radon transform is presented, with emphasis on emission computed tomography and transmission computed tomography. The theory of the 2D and 3D Radon transforms, and the effects of attenuation for emission computed tomography are presented. The algebraic iterative methods, their importance and limitations are reviewed. Analytic solutions of the 2D problem the convolution and frequency filtering methods based on linear shift invariant theory, and the solution of the circular harmonic decomposition by integral transform theory--are reviewed. The relation between the invisible kernels, the inverse circular harmonic transform, and the consistency conditions are demonstrated. The discussion and review are extended to the 3D problem-convolution, frequency filtering, spherical harmonic transform solutions, and consistency conditions. The Cormack algorithm based on reconstruction with Zernike polynomials is reviewed. An analogous algorithm and set of reconstruction polynomials is developed for the spherical harmonic transform. The relations between the consistency conditions, boundary conditions and orthogonal basis functions for the 2D projection harmonics are delineated and extended to the 3D case. The equivalence of the inverse circular harmonic transform, the inverse Radon transform, and the inverse Cormack transform is presented. The use of the number of nodes of a projection harmonic as a filter is discussed. Numerical methods for the efficient implementation of angular harmonic algorithms based on orthogonal functions and stable recursion are presented. The derivation of a lower bound for the signal-to-noise ratio of the Cormack algorithm is derived.

Nano-structured silica coated mesoporous carbon micro-granules for potential application in water filtration

NASA Astrophysics Data System (ADS)

Das, Avik; Sen, D.; Mazumder, S.; Ghosh, A. K.

2017-05-01

A novel nano-composite spherical micro-granule has been synthesized using a facile technique of solvent evaporation induced assembly of nanoparticles for potential application in water filtration. The spherical micro-granule is comprised of nano-structured shell of hydrophilic silica encapsulating a hydrophobic mesoporous carbon at the core. Hierarchical structure of such core-shell micro-granules has been rigorously characterized using small-angle neutron and X-ray scattering techniques and complemented with scanning electron microscopy. The hydrophilic silica envelope around the carbon core helps in incorporation of such granules into the hydrophilic polymeric ultra-filtration membrane. The interstitial micro-pores present in the silica shell can serve as water transport channels and the mesoporus carbon core enhances the separation performance due its well adsorption characteristics. It has been found that the incorporation of such granules inside the ultra-filtration membrane indeed enhances the water permeability as well as the separation performance in a significant way.

High-speed DNA-based rolling motors powered by RNase H

PubMed Central

Yehl, Kevin; Mugler, Andrew; Vivek, Skanda; Liu, Yang; Zhang, Yun; Fan, Mengzhen; Weeks, Eric R.

2016-01-01

DNA-based machines that walk by converting chemical energy into controlled motion could be of use in applications such as next generation sensors, drug delivery platforms, and biological computing. Despite their exquisite programmability, DNA-based walkers are, however, challenging to work with due to their low fidelity and slow rates (~1 nm/min). Here, we report DNA-based machines that roll rather than walk, and consequently have a maximum speed and processivity that is three-orders of magnitude greater than conventional DNA motors. The motors are made from DNA-coated spherical particles that hybridise to a surface modified with complementary RNA; motion is achieved through the addition of RNase H, which selectively hydrolyses hybridised RNA. Spherical motors move in a self-avoiding manner, whereas anisotropic particles, such as dimerised particles or rod-shaped particles travel linearly without a track or external force. Finally, we demonstrate detection of single nucleotide polymorphism by measuring particle displacement using a smartphone camera. PMID:26619152

A green chemical approach for synthesis of shape anisotropic gold nanoparticles

NASA Astrophysics Data System (ADS)

Kalyan Kamal, S. S.; Vimala, J.; Sahoo, P. K.; Ghosal, P.; Ram, S.; Durai, L.

2014-06-01

A complete green chemical reaction between aurochloric acid and tea polyphenols resulted in the reduction of Au3+ → Au0. The reaction was carried out in a Teflon-coated bomb digestion vessel at 200 °C. It was observed that with increasing the reaction time from 1 to 5 h, the shape of the nanoparticles changed from spherical- to rod-like structures. The reaction was followed with the help of UV-vis spectrometer, which showed a single absorption peak at 548 nm for 1-h reaction product and two peaks for a 5-h reaction product at 533 and 745 nm corresponding to the transverse and longitudinal surface plasmon resonance bands. Microstructures obtained from transmission electron microscope revealed that the samples obtained after 1-h reaction are predominantly spherical in shape with an average size of 15 nm. Whereas samples obtained after 5 h of reaction exhibited rod-like structures with an average size of 45 nm.

7 CFR 981.401 - Adjusted kernel weight.

Code of Federal Regulations, 2012 CFR

2012-01-01

... based on the analysis of a 1,000 gram sample taken from a lot of almonds weighing 10,000 pounds with less than 95 percent kernels, and a 1,000 gram sample taken from a lot of almonds weighing 10,000... percent kernels containing the following: Edible kernels, 530 grams; inedible kernels, 120 grams; foreign...

7 CFR 981.401 - Adjusted kernel weight.

Code of Federal Regulations, 2011 CFR

2011-01-01

... based on the analysis of a 1,000 gram sample taken from a lot of almonds weighing 10,000 pounds with less than 95 percent kernels, and a 1,000 gram sample taken from a lot of almonds weighing 10,000... percent kernels containing the following: Edible kernels, 530 grams; inedible kernels, 120 grams; foreign...

7 CFR 981.401 - Adjusted kernel weight.

Code of Federal Regulations, 2013 CFR

2013-01-01

... based on the analysis of a 1,000 gram sample taken from a lot of almonds weighing 10,000 pounds with less than 95 percent kernels, and a 1,000 gram sample taken from a lot of almonds weighing 10,000... percent kernels containing the following: Edible kernels, 530 grams; inedible kernels, 120 grams; foreign...

7 CFR 981.401 - Adjusted kernel weight.

Code of Federal Regulations, 2010 CFR

2010-01-01

... based on the analysis of a 1,000 gram sample taken from a lot of almonds weighing 10,000 pounds with less than 95 percent kernels, and a 1,000 gram sample taken from a lot of almonds weighing 10,000... percent kernels containing the following: Edible kernels, 530 grams; inedible kernels, 120 grams; foreign...

7 CFR 981.401 - Adjusted kernel weight.

Code of Federal Regulations, 2014 CFR

2014-01-01

... based on the analysis of a 1,000 gram sample taken from a lot of almonds weighing 10,000 pounds with less than 95 percent kernels, and a 1,000 gram sample taken from a lot of almonds weighing 10,000... percent kernels containing the following: Edible kernels, 530 grams; inedible kernels, 120 grams; foreign...

7 CFR 51.1441 - Half-kernel.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Half-kernel. 51.1441 Section 51.1441 Agriculture... Standards for Grades of Shelled Pecans Definitions § 51.1441 Half-kernel. Half-kernel means one of the separated halves of an entire pecan kernel with not more than one-eighth of its original volume missing...

7 CFR 51.1403 - Kernel color classification.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Kernel color classification. 51.1403 Section 51.1403... STANDARDS) United States Standards for Grades of Pecans in the Shell 1 Kernel Color Classification § 51.1403 Kernel color classification. (a) The skin color of pecan kernels may be described in terms of the color...

7 CFR 51.1450 - Serious damage.

Code of Federal Regulations, 2010 CFR

2010-01-01

...; (c) Decay affecting any portion of the kernel; (d) Insects, web, or frass or any distinct evidence of insect feeding on the kernel; (e) Internal discoloration which is dark gray, dark brown, or black and...) Dark kernel spots when more than three are on the kernel, or when any dark kernel spot or the aggregate...

7 CFR 51.1450 - Serious damage.

Code of Federal Regulations, 2011 CFR

2011-01-01

...; (c) Decay affecting any portion of the kernel; (d) Insects, web, or frass or any distinct evidence of insect feeding on the kernel; (e) Internal discoloration which is dark gray, dark brown, or black and...) Dark kernel spots when more than three are on the kernel, or when any dark kernel spot or the aggregate...

7 CFR 51.1450 - Serious damage.

Code of Federal Regulations, 2012 CFR

2012-01-01

...; (c) Decay affecting any portion of the kernel; (d) Insects, web, or frass or any distinct evidence of insect feeding on the kernel; (e) Internal discoloration which is dark gray, dark brown, or black and...) Dark kernel spots when more than three are on the kernel, or when any dark kernel spot or the aggregate...

Wavelet SVM in Reproducing Kernel Hilbert Space for hyperspectral remote sensing image classification

NASA Astrophysics Data System (ADS)

Du, Peijun; Tan, Kun; Xing, Xiaoshi

2010-12-01

Combining Support Vector Machine (SVM) with wavelet analysis, we constructed wavelet SVM (WSVM) classifier based on wavelet kernel functions in Reproducing Kernel Hilbert Space (RKHS). In conventional kernel theory, SVM is faced with the bottleneck of kernel parameter selection which further results in time-consuming and low classification accuracy. The wavelet kernel in RKHS is a kind of multidimensional wavelet function that can approximate arbitrary nonlinear functions. Implications on semiparametric estimation are proposed in this paper. Airborne Operational Modular Imaging Spectrometer II (OMIS II) hyperspectral remote sensing image with 64 bands and Reflective Optics System Imaging Spectrometer (ROSIS) data with 115 bands were used to experiment the performance and accuracy of the proposed WSVM classifier. The experimental results indicate that the WSVM classifier can obtain the highest accuracy when using the Coiflet Kernel function in wavelet transform. In contrast with some traditional classifiers, including Spectral Angle Mapping (SAM) and Minimum Distance Classification (MDC), and SVM classifier using Radial Basis Function kernel, the proposed wavelet SVM classifier using the wavelet kernel function in Reproducing Kernel Hilbert Space is capable of improving classification accuracy obviously.

A trace ratio maximization approach to multiple kernel-based dimensionality reduction.

PubMed

Jiang, Wenhao; Chung, Fu-lai

2014-01-01

Most dimensionality reduction techniques are based on one metric or one kernel, hence it is necessary to select an appropriate kernel for kernel-based dimensionality reduction. Multiple kernel learning for dimensionality reduction (MKL-DR) has been recently proposed to learn a kernel from a set of base kernels which are seen as different descriptions of data. As MKL-DR does not involve regularization, it might be ill-posed under some conditions and consequently its applications are hindered. This paper proposes a multiple kernel learning framework for dimensionality reduction based on regularized trace ratio, termed as MKL-TR. Our method aims at learning a transformation into a space of lower dimension and a corresponding kernel from the given base kernels among which some may not be suitable for the given data. The solutions for the proposed framework can be found based on trace ratio maximization. The experimental results demonstrate its effectiveness in benchmark datasets, which include text, image and sound datasets, for supervised, unsupervised as well as semi-supervised settings. Copyright © 2013 Elsevier Ltd. All rights reserved.

Distributed smoothed tree kernel for protein-protein interaction extraction from the biomedical literature

PubMed Central

Murugesan, Gurusamy; Abdulkadhar, Sabenabanu; Natarajan, Jeyakumar

2017-01-01

Automatic extraction of protein-protein interaction (PPI) pairs from biomedical literature is a widely examined task in biological information extraction. Currently, many kernel based approaches such as linear kernel, tree kernel, graph kernel and combination of multiple kernels has achieved promising results in PPI task. However, most of these kernel methods fail to capture the semantic relation information between two entities. In this paper, we present a special type of tree kernel for PPI extraction which exploits both syntactic (structural) and semantic vectors information known as Distributed Smoothed Tree kernel (DSTK). DSTK comprises of distributed trees with syntactic information along with distributional semantic vectors representing semantic information of the sentences or phrases. To generate robust machine learning model composition of feature based kernel and DSTK were combined using ensemble support vector machine (SVM). Five different corpora (AIMed, BioInfer, HPRD50, IEPA, and LLL) were used for evaluating the performance of our system. Experimental results show that our system achieves better f-score with five different corpora compared to other state-of-the-art systems. PMID:29099838

Hadamard Kernel SVM with applications for breast cancer outcome predictions.

PubMed

Jiang, Hao; Ching, Wai-Ki; Cheung, Wai-Shun; Hou, Wenpin; Yin, Hong

2017-12-21

Breast cancer is one of the leading causes of deaths for women. It is of great necessity to develop effective methods for breast cancer detection and diagnosis. Recent studies have focused on gene-based signatures for outcome predictions. Kernel SVM for its discriminative power in dealing with small sample pattern recognition problems has attracted a lot attention. But how to select or construct an appropriate kernel for a specified problem still needs further investigation. Here we propose a novel kernel (Hadamard Kernel) in conjunction with Support Vector Machines (SVMs) to address the problem of breast cancer outcome prediction using gene expression data. Hadamard Kernel outperform the classical kernels and correlation kernel in terms of Area under the ROC Curve (AUC) values where a number of real-world data sets are adopted to test the performance of different methods. Hadamard Kernel SVM is effective for breast cancer predictions, either in terms of prognosis or diagnosis. It may benefit patients by guiding therapeutic options. Apart from that, it would be a valuable addition to the current SVM kernel families. We hope it will contribute to the wider biology and related communities.

Distributed smoothed tree kernel for protein-protein interaction extraction from the biomedical literature.

PubMed

Murugesan, Gurusamy; Abdulkadhar, Sabenabanu; Natarajan, Jeyakumar

2017-01-01

Automatic extraction of protein-protein interaction (PPI) pairs from biomedical literature is a widely examined task in biological information extraction. Currently, many kernel based approaches such as linear kernel, tree kernel, graph kernel and combination of multiple kernels has achieved promising results in PPI task. However, most of these kernel methods fail to capture the semantic relation information between two entities. In this paper, we present a special type of tree kernel for PPI extraction which exploits both syntactic (structural) and semantic vectors information known as Distributed Smoothed Tree kernel (DSTK). DSTK comprises of distributed trees with syntactic information along with distributional semantic vectors representing semantic information of the sentences or phrases. To generate robust machine learning model composition of feature based kernel and DSTK were combined using ensemble support vector machine (SVM). Five different corpora (AIMed, BioInfer, HPRD50, IEPA, and LLL) were used for evaluating the performance of our system. Experimental results show that our system achieves better f-score with five different corpora compared to other state-of-the-art systems.

LZW-Kernel: fast kernel utilizing variable length code blocks from LZW compressors for protein sequence classification.

PubMed

Filatov, Gleb; Bauwens, Bruno; Kertész-Farkas, Attila

2018-05-07

Bioinformatics studies often rely on similarity measures between sequence pairs, which often pose a bottleneck in large-scale sequence analysis. Here, we present a new convolutional kernel function for protein sequences called the LZW-Kernel. It is based on code words identified with the Lempel-Ziv-Welch (LZW) universal text compressor. The LZW-Kernel is an alignment-free method, it is always symmetric, is positive, always provides 1.0 for self-similarity and it can directly be used with Support Vector Machines (SVMs) in classification problems, contrary to normalized compression distance (NCD), which often violates the distance metric properties in practice and requires further techniques to be used with SVMs. The LZW-Kernel is a one-pass algorithm, which makes it particularly plausible for big data applications. Our experimental studies on remote protein homology detection and protein classification tasks reveal that the LZW-Kernel closely approaches the performance of the Local Alignment Kernel (LAK) and the SVM-pairwise method combined with Smith-Waterman (SW) scoring at a fraction of the time. Moreover, the LZW-Kernel outperforms the SVM-pairwise method when combined with BLAST scores, which indicates that the LZW code words might be a better basis for similarity measures than local alignment approximations found with BLAST. In addition, the LZW-Kernel outperforms n-gram based mismatch kernels, hidden Markov model based SAM and Fisher kernel, and protein family based PSI-BLAST, among others. Further advantages include the LZW-Kernel's reliance on a simple idea, its ease of implementation, and its high speed, three times faster than BLAST and several magnitudes faster than SW or LAK in our tests. LZW-Kernel is implemented as a standalone C code and is a free open-source program distributed under GPLv3 license and can be downloaded from https://github.com/kfattila/LZW-Kernel. akerteszfarkas@hse.ru. Supplementary data are available at Bioinformatics Online.

A framework for optimal kernel-based manifold embedding of medical image data.

PubMed

Zimmer, Veronika A; Lekadir, Karim; Hoogendoorn, Corné; Frangi, Alejandro F; Piella, Gemma

2015-04-01

Kernel-based dimensionality reduction is a widely used technique in medical image analysis. To fully unravel the underlying nonlinear manifold the selection of an adequate kernel function and of its free parameters is critical. In practice, however, the kernel function is generally chosen as Gaussian or polynomial and such standard kernels might not always be optimal for a given image dataset or application. In this paper, we present a study on the effect of the kernel functions in nonlinear manifold embedding of medical image data. To this end, we first carry out a literature review on existing advanced kernels developed in the statistics, machine learning, and signal processing communities. In addition, we implement kernel-based formulations of well-known nonlinear dimensional reduction techniques such as Isomap and Locally Linear Embedding, thus obtaining a unified framework for manifold embedding using kernels. Subsequently, we present a method to automatically choose a kernel function and its associated parameters from a pool of kernel candidates, with the aim to generate the most optimal manifold embeddings. Furthermore, we show how the calculated selection measures can be extended to take into account the spatial relationships in images, or used to combine several kernels to further improve the embedding results. Experiments are then carried out on various synthetic and phantom datasets for numerical assessment of the methods. Furthermore, the workflow is applied to real data that include brain manifolds and multispectral images to demonstrate the importance of the kernel selection in the analysis of high-dimensional medical images. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluating the Gradient of the Thin Wire Kernel

NASA Technical Reports Server (NTRS)

Wilton, Donald R.; Champagne, Nathan J.

2008-01-01

Recently, a formulation for evaluating the thin wire kernel was developed that employed a change of variable to smooth the kernel integrand, canceling the singularity in the integrand. Hence, the typical expansion of the wire kernel in a series for use in the potential integrals is avoided. The new expression for the kernel is exact and may be used directly to determine the gradient of the wire kernel, which consists of components that are parallel and radial to the wire axis.

Kernel Machine SNP-set Testing under Multiple Candidate Kernels

PubMed Central

Wu, Michael C.; Maity, Arnab; Lee, Seunggeun; Simmons, Elizabeth M.; Harmon, Quaker E.; Lin, Xinyi; Engel, Stephanie M.; Molldrem, Jeffrey J.; Armistead, Paul M.

2013-01-01

Joint testing for the cumulative effect of multiple single nucleotide polymorphisms grouped on the basis of prior biological knowledge has become a popular and powerful strategy for the analysis of large scale genetic association studies. The kernel machine (KM) testing framework is a useful approach that has been proposed for testing associations between multiple genetic variants and many different types of complex traits by comparing pairwise similarity in phenotype between subjects to pairwise similarity in genotype, with similarity in genotype defined via a kernel function. An advantage of the KM framework is its flexibility: choosing different kernel functions allows for different assumptions concerning the underlying model and can allow for improved power. In practice, it is difficult to know which kernel to use a priori since this depends on the unknown underlying trait architecture and selecting the kernel which gives the lowest p-value can lead to inflated type I error. Therefore, we propose practical strategies for KM testing when multiple candidate kernels are present based on constructing composite kernels and based on efficient perturbation procedures. We demonstrate through simulations and real data applications that the procedures protect the type I error rate and can lead to substantially improved power over poor choices of kernels and only modest differences in power versus using the best candidate kernel. PMID:23471868

Combined multi-kernel head computed tomography images optimized for depicting both brain parenchyma and bone.

PubMed

Takagi, Satoshi; Nagase, Hiroyuki; Hayashi, Tatsuya; Kita, Tamotsu; Hayashi, Katsumi; Sanada, Shigeru; Koike, Masayuki

2014-01-01

The hybrid convolution kernel technique for computed tomography (CT) is known to enable the depiction of an image set using different window settings. Our purpose was to decrease the number of artifacts in the hybrid convolution kernel technique for head CT and to determine whether our improved combined multi-kernel head CT images enabled diagnosis as a substitute for both brain (low-pass kernel-reconstructed) and bone (high-pass kernel-reconstructed) images. Forty-four patients with nondisplaced skull fractures were included. Our improved multi-kernel images were generated so that pixels of >100 Hounsfield unit in both brain and bone images were composed of CT values of bone images and other pixels were composed of CT values of brain images. Three radiologists compared the improved multi-kernel images with bone images. The improved multi-kernel images and brain images were identically displayed on the brain window settings. All three radiologists agreed that the improved multi-kernel images on the bone window settings were sufficient for diagnosing skull fractures in all patients. This improved multi-kernel technique has a simple algorithm and is practical for clinical use. Thus, simplified head CT examinations and fewer images that need to be stored can be expected.

Fluidized bed coupled rotary reactor for nanoparticles coating via atomic layer deposition

NASA Astrophysics Data System (ADS)

Duan, Chen-Long; Liu, Xiao; Shan, Bin; Chen, Rong

2015-07-01

A fluidized bed coupled rotary reactor has been designed for coating on nanoparticles (NPs) via atomic layer deposition. It consists of five major parts: reaction chamber, dosing and fluidizing section, pumping section, rotary manipulator components, as well as a double-layer cartridge for the storage of particles. In the deposition procedure, continuous fluidization of particles enlarges and homogenizes the void fraction in the particle bed, while rotation enhances the gas-solid interactions to stabilize fluidization. The particle cartridge presented here enables both the fluidization and rotation acting on the particle bed, demonstrated by the analysis of pressure drop. Moreover, enlarged interstitials and intense gas-solid contact under sufficient fluidizing velocity and proper rotation speed facilitate the precursor delivery throughout the particle bed and consequently provide a fast coating process. The cartridge can ensure precursors flowing through the particle bed exclusively to achieve high utilization without static exposure operation. By optimizing superficial gas velocities and rotation speeds, minimum pulse time for complete coating has been shortened in experiment, and in situ mass spectrometry showed the precursor usage can reach 90%. Inductively coupled plasma-optical emission spectroscopy results suggested a saturated growth of nanoscale Al2O3 films on spherical SiO2 NPs. Finally, the uniformity and composition of the shells were characterized by high angle annular dark field-transmission electron microscopy and energy dispersive X-ray spectroscopy.

Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

2018-01-01

Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

Evaluation of adhesion force between functionalized microbeads and protein-coated stainless steel using shear-flow-induced detachment.

PubMed

Mercier-Bonin, Muriel; Adoue, Mathieu; Zanna, Sandrine; Marcus, Philippe; Combes, Didier; Schmitz, Philippe

2009-10-01

Spherical microbeads functionalized with two types of chemical groups (NH(2), OH) were chosen as a simplified bacterial model, in order to elucidate the role of macromolecular interactions between specific biopolymers and 316 L stainless steel, in the frame of biofilm formation in the marine environment. NH(2) microbeads were used in their native form or after covalent binding to BSA or different representative poly-amino acids. OH microbeads were used in their native form. Adhesion force between microbeads and bare or BSA-coated stainless steel was quantified at nanoscale. Shear-flow-induced detachment experiments were combined with a simplified version of a theoretical model, based on the balance of hydrodynamic forces and torque exerted on microbeads. A maximal adhesion force of 27.6+/-8.5 nN was obtained for BSA-coated NH(2) microbeads. The high reactivity of OH functional groups was assessed (adhesion force of 15.6+/-4.8 nN for large microbeads). When charge-conducting stainless steel was coated with BSA, adhesion force was significantly lower than the one estimated with the bare surface, probably due to an increase in hydrophilic surface properties or suppression of charge transfer. The mechanism for microbead detachment was established (mainly rolling). The flow chamber and the associated theoretical modelling were demonstrated to be a relevant approach to quantify nanoscale forces between interacting surfaces.

7 CFR 810.202 - Definition of other terms.

Code of Federal Regulations, 2014 CFR

2014-01-01

... barley kernels, other grains, and wild oats that are badly shrunken and distinctly discolored black or... kernels. Kernels and pieces of barley kernels that are distinctly indented, immature or shrunken in...

7 CFR 810.202 - Definition of other terms.

Code of Federal Regulations, 2013 CFR

2013-01-01

... barley kernels, other grains, and wild oats that are badly shrunken and distinctly discolored black or... kernels. Kernels and pieces of barley kernels that are distinctly indented, immature or shrunken in...

7 CFR 810.202 - Definition of other terms.

Code of Federal Regulations, 2012 CFR

2012-01-01

... barley kernels, other grains, and wild oats that are badly shrunken and distinctly discolored black or... kernels. Kernels and pieces of barley kernels that are distinctly indented, immature or shrunken in...

graphkernels: R and Python packages for graph comparison

PubMed Central

Ghisu, M Elisabetta; Llinares-López, Felipe; Borgwardt, Karsten

2018-01-01

Abstract Summary Measuring the similarity of graphs is a fundamental step in the analysis of graph-structured data, which is omnipresent in computational biology. Graph kernels have been proposed as a powerful and efficient approach to this problem of graph comparison. Here we provide graphkernels, the first R and Python graph kernel libraries including baseline kernels such as label histogram based kernels, classic graph kernels such as random walk based kernels, and the state-of-the-art Weisfeiler-Lehman graph kernel. The core of all graph kernels is implemented in C ++ for efficiency. Using the kernel matrices computed by the package, we can easily perform tasks such as classification, regression and clustering on graph-structured samples. Availability and implementation The R and Python packages including source code are available at https://CRAN.R-project.org/package=graphkernels and https://pypi.python.org/pypi/graphkernels. Contact mahito@nii.ac.jp or elisabetta.ghisu@bsse.ethz.ch Supplementary information Supplementary data are available online at Bioinformatics. PMID:29028902

graphkernels: R and Python packages for graph comparison.

PubMed

Sugiyama, Mahito; Ghisu, M Elisabetta; Llinares-López, Felipe; Borgwardt, Karsten

2018-02-01

Measuring the similarity of graphs is a fundamental step in the analysis of graph-structured data, which is omnipresent in computational biology. Graph kernels have been proposed as a powerful and efficient approach to this problem of graph comparison. Here we provide graphkernels, the first R and Python graph kernel libraries including baseline kernels such as label histogram based kernels, classic graph kernels such as random walk based kernels, and the state-of-the-art Weisfeiler-Lehman graph kernel. The core of all graph kernels is implemented in C ++ for efficiency. Using the kernel matrices computed by the package, we can easily perform tasks such as classification, regression and clustering on graph-structured samples. The R and Python packages including source code are available at https://CRAN.R-project.org/package=graphkernels and https://pypi.python.org/pypi/graphkernels. mahito@nii.ac.jp or elisabetta.ghisu@bsse.ethz.ch. Supplementary data are available online at Bioinformatics. © The Author(s) 2017. Published by Oxford University Press.

Investigation of various energy deposition kernel refinements for the convolution/superposition method

PubMed Central

Huang, Jessie Y.; Eklund, David; Childress, Nathan L.; Howell, Rebecca M.; Mirkovic, Dragan; Followill, David S.; Kry, Stephen F.

2013-01-01

Purpose: Several simplifications used in clinical implementations of the convolution/superposition (C/S) method, specifically, density scaling of water kernels for heterogeneous media and use of a single polyenergetic kernel, lead to dose calculation inaccuracies. Although these weaknesses of the C/S method are known, it is not well known which of these simplifications has the largest effect on dose calculation accuracy in clinical situations. The purpose of this study was to generate and characterize high-resolution, polyenergetic, and material-specific energy deposition kernels (EDKs), as well as to investigate the dosimetric impact of implementing spatially variant polyenergetic and material-specific kernels in a collapsed cone C/S algorithm. Methods: High-resolution, monoenergetic water EDKs and various material-specific EDKs were simulated using the EGSnrc Monte Carlo code. Polyenergetic kernels, reflecting the primary spectrum of a clinical 6 MV photon beam at different locations in a water phantom, were calculated for different depths, field sizes, and off-axis distances. To investigate the dosimetric impact of implementing spatially variant polyenergetic kernels, depth dose curves in water were calculated using two different implementations of the collapsed cone C/S method. The first method uses a single polyenergetic kernel, while the second method fully takes into account spectral changes in the convolution calculation. To investigate the dosimetric impact of implementing material-specific kernels, depth dose curves were calculated for a simplified titanium implant geometry using both a traditional C/S implementation that performs density scaling of water kernels and a novel implementation using material-specific kernels. Results: For our high-resolution kernels, we found good agreement with the Mackie et al. kernels, with some differences near the interaction site for low photon energies (<500 keV). For our spatially variant polyenergetic kernels, we found that depth was the most dominant factor affecting the pattern of energy deposition; however, the effects of field size and off-axis distance were not negligible. For the material-specific kernels, we found that as the density of the material increased, more energy was deposited laterally by charged particles, as opposed to in the forward direction. Thus, density scaling of water kernels becomes a worse approximation as the density and the effective atomic number of the material differ more from water. Implementation of spatially variant, polyenergetic kernels increased the percent depth dose value at 25 cm depth by 2.1%–5.8% depending on the field size, while implementation of titanium kernels gave 4.9% higher dose upstream of the metal cavity (i.e., higher backscatter dose) and 8.2% lower dose downstream of the cavity. Conclusions: Of the various kernel refinements investigated, inclusion of depth-dependent and metal-specific kernels into the C/S method has the greatest potential to improve dose calculation accuracy. Implementation of spatially variant polyenergetic kernels resulted in a harder depth dose curve and thus has the potential to affect beam modeling parameters obtained in the commissioning process. For metal implants, the C/S algorithms generally underestimate the dose upstream and overestimate the dose downstream of the implant. Implementation of a metal-specific kernel mitigated both of these errors. PMID:24320507

Development of new magnetic nanoparticles: Oligochitosan obtained by γ-rays and -coated Fe3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Le Thi, Thao Nguyen; Nguyen, Thi Hiep; Hoang, Dong Quy; Tran, Tuong, Vi; Nguyen, Ngoc Thuy; Nguyen, Dai Hai

2017-11-01

Oligochitosan (OCS) have been utilized as a potential bioactive material for improving food quality and human health. In this study, superparamagnetic iron oxide (Fe3O4) nanoparticles were originally coated with OCS irradiated by gamma rays for their possible biomedical applications. The formation of Fe3O4@OCS was characterized by Fourier transform infrared (FT-IR), X-ray diffraction patterns (XRD), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). In addition, the superparamagnetic properties and sizes and morphologies of Fe3O4 and Fe3O4@OCS nanoparticles were demonstrated by vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM), respectively. These results indicated that Fe3O4@OCS nanoparticles still maintained their superparamagnetic properties after polymeric coating, and were nearly spherical in shape with average diameter of 14.4 ± 0.31 nm, compared with 11.8 ± 0.52 nm of bare Fe3O4 nanoparticles, respectively. As a result, Fe3O4@OCS nanoparticles may serve as a promising platform for the development of new magnetic materials, which could be useful for biomedical applications.

Cadmium sulphide (CdS) thin films deposited by chemical bath deposition (CBD) and dip coating techniques—a comparative study

NASA Astrophysics Data System (ADS)

Khimani, Ankurkumar J.; Chaki, Sunil H.; Malek, Tasmira J.; Tailor, Jiten P.; Chauhan, Sanjaysinh M.; Deshpande, M. P.

2018-03-01

The CdS thin films were deposited on glass slide substrates by Chemical Bath Deposition and dip coating techniques. The films thickness variation with deposition time showed maximum films deposition at 35 min for both the films. The energy dispersive analysis of x-ray showed both the films to be stoichiometric. The x-ray diffraction analysis confirmed the films possess hexagonal crystal structure. The transmission electron, scanning electron and optical microscopy study showed the films deposition to be uniform. The selected area electron diffraction exhibited ring patterns stating the films to be polycrystalline in nature. The atomic force microscopy images showed surface formed of spherical grains, hills and valleys. The recorded optical absorbance spectra analysis revealed the films possess direct optical bandgap having values of 2.25 eV for CBD and 2.40 eV for dip coating. The refractive index (η), extinction coefficient (k), complex dielectric constant (ε) and optical conductivity (σ 0) variation with wavelength showed maximum photon absorption till the respective wavelengths corresponding to the optical bandgap energy values. The recorded photoluminescence spectra showed two emission peaks. All the obtained results have been discussed in details.

Diffusiophoretic self-propulsion for partially catalytic spherical colloids.

PubMed

de Graaf, Joost; Rempfer, Georg; Holm, Christian

2015-04-01

Colloidal spheres with a partial platinum surface coating perform autophoretic motion when suspended in hydrogen peroxide solution. We present a theoretical analysis of the self-propulsion velocity of these particles using a continuum multi-component, self-diffusiophoretic model. With this model as a basis, we show how the slip-layer approximation can be derived and in which limits it holds. First, we consider the differences between the full multi-component model and the slip-layer approximation. Then the slip model is used to demonstrate and explore the sensitive nature of the particle's velocity on the details of the molecule-surface interaction. We find a strong asymmetry in the dependence of the colloid's velocity as a function of the level of catalytic coating, when there is a different interaction between the solute and solvent molecules and the inert and catalytic part of the colloid, respectively. The direction of motion can even be reversed by varying the level of the catalytic coating. Finally, we investigate the robustness of these results with respect to variations in the reaction rate near the edge between the catalytic and inert parts of the particle. Our results are of significant interest to the interpretation of experimental results on the motion of self-propelled particles.

Sustainable synthesis of magnetically separable SiO2/Co@Fe2O4 nanocomposite and its catalytic applications for the benzimidazole synthesis

NASA Astrophysics Data System (ADS)

Jithendra Kumara, K. S.; Krishnamurthy, G.; Sunil Kumar, N.; Naik, Nagaraja; Praveen, T. M.

2018-04-01

The Co(II) and Fe(III) centres magnetically separable two new mesoporous nanocatalyst were synthesised via chemical synthesis method. The transmission electron microscopic studies (TEM) show that, the particles are spherical shape with mean size of 20 nm. The Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) reveals that SiO2 is coating on the surface of the cobalt ferrate nanoparticle (CoFe2O4). The SiO2 coating is efficiently preventing the aggregated collision of nanoparticles. Magnetic measurements show that diamagnetic character of the SiO2 is unaffected to the coercivity of SiO2 coated CoFe2O4 particles. In addition, these nanoparticles are used as nanocatalyst for high yielding, facile and expeditious synthesis of various functionalized 2-arylbenzimidazoles via one-pot condensation. The cascade including imine formation, cyclization, condensation, and aromatization occurs, without addition of any reducing or oxidizing agents. In all situations, the desired product was synthesised with excellent yield. The shorter reaction time, mild reaction condition, simplicity, non-toxicity, safe reaction and easy workup are the impotent merits of this protocol.

Soft lubrication: The elastohydrodynamics of nonconforming and conforming contacts

NASA Astrophysics Data System (ADS)

Skotheim, J. M.; Mahadevan, L.

2005-09-01

We study the lubrication of fluid-immersed soft interfaces and show that elastic deformation couples tangential and normal forces and thus generates lift. We consider materials that deform easily, due to either geometry (e.g., a shell) or constitutive properties (e.g., a gel or a rubber), so that the effects of pressure and temperature on the fluid properties may be neglected. Four different system geometries are considered: a rigid cylinder moving parallel to a soft layer coating a rigid substrate; a soft cylinder moving parallel to a rigid substrate; a cylindrical shell moving parallel to a rigid substrate; and finally a cylindrical conforming journal bearing coated with a thin soft layer. In addition, for the particular case of a soft layer coating a rigid substrate, we consider both elastic and poroelastic material responses. For all these cases, we find the same generic behavior: there is an optimal combination of geometric and material parameters that maximizes the dimensionless normal force as a function of the softness parameter η =hydrodynamicpressure/elasticstiffness=surfacedeflection/gapthickness, which characterizes the fluid-induced deformation of the interface. The corresponding cases for a spherical slider are treated using scaling concepts.

Simultaneous qualitative assessment and quantitative analysis of flavonoids in various tissues of lotus (Nelumbo nucifera) using high performance liquid chromatography coupled with triple quad mass spectrometry.

PubMed

Chen, Sha; Fang, Linchuan; Xi, Huifen; Guan, Le; Fang, Jinbao; Liu, Yanling; Wu, Benhong; Li, Shaohua

2012-04-29

Flavonoid composition and concentration were investigated in 12 different tissues of 'Ti-1' lotus (Nelumbo nucifera) by high performance liquid chromatography equipped with photodiode array detection tandem electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS(n)). A total of 20 flavonoids belonging to six groups (myricetin, quercetin, kaempferol, isohamnetin, diosmetin derivatives) were separated and identified. Myricetin 3-O-galactoside, myricetin 3-O-glucuronide, isorhamnetin 3-O-glucuronide and free aglycone diometin (3',5,7-trihydroxy-4'-methoxyflavone) were first reported in lotus. Flavonoid composition varied largely with tissue type, and diverse compounds (5-15) were found in leaf and flower stalks, flower pistils, seed coats and embryos. Flower tissues including flower petals, stamens, pistils, and, especially, reproductive tissue fruit coats had more flavonoid compounds (15-17) than leaves (12), while no flavonoids were detectable in seed kernels. The flavonoid content of seed embryos was high, 730.95 mg 100g(-1) DW (dry weight). As regards the other tissues, mature leaf pulp (771.79 mg 100 g(-1) FW (fresh weight)) and young leaves (650.67 mg 100 g(-1) FW) had higher total flavonoid amount than flower stamens (359.45 mg 100 g(-1) FW) and flower petals (342.97 mg 100g(-1) FW), while leaf stalks, flower stalks and seed coats had much less total flavonoid (less than 40 mg 100 g(-1) FW). Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation of wormlike polymeric nanoparticles coated with silica for delivery of methotrexate and evaluation of anticancer activity against MCF7 cells.

PubMed

Gharebaghi, Farhad; Dalali, Naser; Ahmadi, Ebrahim; Danafar, Hossein

2017-04-01

Methotrexate is one of the most effective drugs that is commonly used in the treatment of cancer. However, its application is limited due to low solubility, high toxicity and rapid metabolism. Therefore, in the present study, worm-like polymeric nanoparticles as carrier of methotrexate were prepared using biodegradable copolymers (mPEG-PCL). The impact of nanoparticles' geometry on the loading, delivery and drug's anti-cancer activity was investigated. The di-block copolymer mPEG-PCL was being synthesized by a ring opening polymerization of ɛ-caprolactone in the presence of mPEG as the initiator and Sn(oct) 2 as the catalyst. It was used for the preparation of worm-like micelles and coated with silica, so that their structures are stable after drying. The synthesized copolymers and nanoparticles were characterized by FTIR, HNMR, GPC, XRD, TGA, DLS, and FE-SEM analyses. The efficiencies of drug loading and release of nanoparticles as in vitro, was studied by high performance liquid chromatography. The MTT method was used to estimate the toxicity on MCF-7 cell category. The obtained results showed that the nanoparticles were worm-like particles with less than 150 nm diameter and about 1 µm length. The loading and encapsulation efficiencies of drug by the worm-like nanoparticles were 3.5 ± 0.14% and 65.6 ± 0.12%, respectively, while they were obtained as 2.1 ± 0.08% and 26 ± 0.10%, respectively, for spherical nanoparticles. The methotrexate diffusional behavior of worm-like nanoparticles was compared with that of the spherical ones. On the other hand, the anti-cancer activity of MTX-loaded nanoparticles was more than the free drug. The results of the MTT assay showed strong and dose-dependent inhibition of cell (MCF-7 category) growth by the nanoparticles compared with MTX. The inhibitory concentrations (IC 50 i.e. reduction viability of cell to 50%) obtained for worm-like, spherical nanoparticles and free drug (incubation times 72 h) were 8.25 ± 0.20, 9.15 ± 0.17, 12.28 ± 0.15 µg/mL, respectively. It can be concluded that application of non-spherical nanoparticles is a better and more effective strategy for controlled and slow release of methotrexate in the treatment of cancer.

Investigating the role of particle shape on colloid transport and retention in saturated porous media (Invited)

NASA Astrophysics Data System (ADS)

Li, Y.; Seymour, M.; Chen, G.; Su, C.

2013-12-01

Mechanistic understanding of the transport and retention of nanoparticles in porous media is essential both for environmental applications of nanotechnology and assessing the potential environmental impacts of engineered nanomaterials. Engineered and naturally occurring nanoparticles can be found in various shapes including rod-shape carbon nanotubes that have high aspect ratios. Although it is expected that nonspherical shape could play an important role on their transport and retention behaviors, current theoretical models for particle transport in porous media, however, are mostly based on spherical particle shape. In this work, the effect of particle shape on its transport and retention in porous media was evaluated by stretching carboxylate-modified fluorescent polystyrene spheres into rod shapes with aspect ratios of 2:1 and 4:1. Quartz crystal microbalance with dissipation experiments (QCM-D) were conducted to measure the deposition rates of spherical and rod-shaped nanoparticles to the collector (poly-L-lysine coated silica sensor) surface under favorable conditions. Under unfavorable conditions, the retention of nanoparticles in a microfluidic flow cell packed with glass beads was studied with the use of laser scanning cytometry (LSC). Under favorable conditions, the spherical particles displayed a significantly higher deposition rate compared with that of the rod-shaped particles. Theoretical analysis based on Smoluchowski-Levich approximation indicated that the rod-shaped particles largely counterbalance the attractive energies due to higher hydrodynamic forces and torques experienced during their transport and rotation. Under unfavorable conditions, significantly more attachment was observed for rod-shaped particles than spherical particles, and the attachment rate of the rod-shaped particles showed an increasing trend with the increase in injection volume. Rod-shaped particles were found to be less sensitive to the surface charge heterogeneity change than spherical particles. Increased attachment rate of rod-shaped particles was attributed to surface heterogeneity and possibly enhanced hydrophobicity during the stretching process.

Comparing Alternative Kernels for the Kernel Method of Test Equating: Gaussian, Logistic, and Uniform Kernels. Research Report. ETS RR-08-12

ERIC Educational Resources Information Center

Lee, Yi-Hsuan; von Davier, Alina A.

2008-01-01

The kernel equating method (von Davier, Holland, & Thayer, 2004) is based on a flexible family of equipercentile-like equating functions that use a Gaussian kernel to continuize the discrete score distributions. While the classical equipercentile, or percentile-rank, equating method carries out the continuization step by linear interpolation,…

7 CFR 810.204 - Grades and grade requirements for Six-rowed Malting barley and Six-rowed Blue Malting barley.

Code of Federal Regulations, 2010 CFR

2010-01-01

...— Damaged kernels 1 (percent) Foreign material (percent) Other grains (percent) Skinned and broken kernels....0 10.0 15.0 1 Injured-by-frost kernels and injured-by-mold kernels are not considered damaged kernels or considered against sound barley. Notes: Malting barley shall not be infested in accordance with...

7 CFR 51.1413 - Damage.

Code of Federal Regulations, 2013 CFR

2013-01-01

... well cured; (e) Poorly developed kernels; (f) Kernels which are dark amber in color; (g) Kernel spots when more than one dark spot is present on either half of the kernel, or when any such spot is more...

7 CFR 51.1413 - Damage.

Code of Federal Regulations, 2014 CFR

2014-01-01

... well cured; (e) Poorly developed kernels; (f) Kernels which are dark amber in color; (g) Kernel spots when more than one dark spot is present on either half of the kernel, or when any such spot is more...

7 CFR 810.205 - Grades and grade requirements for Two-rowed Malting barley.

Code of Federal Regulations, 2010 CFR

2010-01-01

... (percent) Maximum limits of— Wild oats (percent) Foreign material (percent) Skinned and broken kernels... Injured-by-frost kernels and injured-by-mold kernels are not considered damaged kernels or considered...

Glass and glass-ceramic photonic systems

NASA Astrophysics Data System (ADS)

Zur, Lidia; Thi Ngoc Tran, Lam; Meneghetti, Marcello; Varas, Stefano; Armellini, Cristina; Ristic, Davor; Chiasera, Alessandro; Scotognella, Francesco; Pelli, Stefano; Nunzi Conti, Gualtiero; Boulard, Brigitte; Zonta, Daniele; Dorosz, Dominik; Lukowiak, Anna; Righini, Giancarlo C.; Ramponi, Roberta; Ferrari, Maurizio

2017-02-01

The development of optically confined structure is a major topic in both basic and applied physics not solely ICT oriented but also concerning lighting, laser, sensing, energy, environment, biological and medical sciences, and quantum optics. Glasses and glass-ceramics activated by rare earth ions are the bricks of such structures. Glass-ceramics are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing developing new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. The dependence of the final product on the specific parent glass and on the fabrication protocol still remain an important task of the research in material science. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including optical amplifiers, monolithic waveguide laser, novel sensors, coating of spherical microresonators, and up and down converters. This paper presents some results obtained by our consortium regarding glass-based photonics systems. We will comment the energy transfer mechanism in transparent glass ceramics taking as examples the up and down conversion systems and the role of SnO2 nanocrystals as sensitizers. Coating of spherical resonators by glass ceramics, 1D-Photonic Crystals for luminescence enhancement, laser action and disordered 1-D photonic structures will be also discussed. Finally, RF-Sputtered rare earth doped P2O5- SiO2-Al2O3-Na2O-Er2O3 planar waveguides, will be presented.

In vivo automated quantification of quality of apples during storage using optical coherence tomography images

NASA Astrophysics Data System (ADS)

Srivastava, Vishal; Dalal, Devjyoti; Kumar, Anuj; Prakash, Surya; Dalal, Krishna

2018-06-01

Moisture content is an important feature of fruits and vegetables. As 80% of apple content is water, so decreasing the moisture content will degrade the quality of apples (Golden Delicious). The computational and texture features of the apples were extracted from optical coherence tomography (OCT) images. A support vector machine with a Gaussian kernel model was used to perform automated classification. To evaluate the quality of wax coated apples during storage in vivo, our proposed method opens up the possibility of fully automated quantitative analysis based on the morphological features of apples. Our results demonstrate that the analysis of the computational and texture features of OCT images may be a good non-destructive method for the assessment of the quality of apples.

Detection of ochratoxin A contamination in stored wheat using near-infrared hyperspectral imaging

NASA Astrophysics Data System (ADS)

Senthilkumar, T.; Jayas, D. S.; White, N. D. G.; Fields, P. G.; Gräfenhan, T.

2017-03-01

Near-infrared (NIR) hyperspectral imaging system was used to detect five concentration levels of ochratoxin A (OTA) in contaminated wheat kernels. The wheat kernels artificially inoculated with two different OTA producing Penicillium verrucosum strains, two different non-toxigenic P. verrucosum strains, and sterile control wheat kernels were subjected to NIR hyperspectral imaging. The acquired three-dimensional data were reshaped into readable two-dimensional data. Principal Component Analysis (PCA) was applied to the two dimensional data to identify the key wavelengths which had greater significance in detecting OTA contamination in wheat. Statistical and histogram features extracted at the key wavelengths were used in the linear, quadratic and Mahalanobis statistical discriminant models to differentiate between sterile control, five concentration levels of OTA contamination in wheat kernels, and five infection levels of non-OTA producing P. verrucosum inoculated wheat kernels. The classification models differentiated sterile control samples from OTA contaminated wheat kernels and non-OTA producing P. verrucosum inoculated wheat kernels with a 100% accuracy. The classification models also differentiated between five concentration levels of OTA contaminated wheat kernels and between five infection levels of non-OTA producing P. verrucosum inoculated wheat kernels with a correct classification of more than 98%. The non-OTA producing P. verrucosum inoculated wheat kernels and OTA contaminated wheat kernels subjected to hyperspectral imaging provided different spectral patterns.

Application of kernel method in fluorescence molecular tomography

NASA Astrophysics Data System (ADS)

Zhao, Yue; Baikejiang, Reheman; Li, Changqing

2017-02-01

Reconstruction of fluorescence molecular tomography (FMT) is an ill-posed inverse problem. Anatomical guidance in the FMT reconstruction can improve FMT reconstruction efficiently. We have developed a kernel method to introduce the anatomical guidance into FMT robustly and easily. The kernel method is from machine learning for pattern analysis and is an efficient way to represent anatomical features. For the finite element method based FMT reconstruction, we calculate a kernel function for each finite element node from an anatomical image, such as a micro-CT image. Then the fluorophore concentration at each node is represented by a kernel coefficient vector and the corresponding kernel function. In the FMT forward model, we have a new system matrix by multiplying the sensitivity matrix with the kernel matrix. Thus, the kernel coefficient vector is the unknown to be reconstructed following a standard iterative reconstruction process. We convert the FMT reconstruction problem into the kernel coefficient reconstruction problem. The desired fluorophore concentration at each node can be calculated accordingly. Numerical simulation studies have demonstrated that the proposed kernel-based algorithm can improve the spatial resolution of the reconstructed FMT images. In the proposed kernel method, the anatomical guidance can be obtained directly from the anatomical image and is included in the forward modeling. One of the advantages is that we do not need to segment the anatomical image for the targets and background.

Development and optimization of enteric coated mucoadhesive microspheres of duloxetine hydrochloride using 32 full factorial design

PubMed Central

Setia, Anupama; Kansal, Sahil; Goyal, Naveen

2013-01-01

Background: Microspheres constitute an important part of oral drug delivery system by virtue of their small size and efficient carrier capacity. However, the success of these microspheres is limited due to their short residence time at the site of absorption. Objective: The objective of the present study was to formulate and systematically evaluate in vitro performance of enteric coated mucoadhesive microspheres of duloxetine hydrochloride (DLX), an acid labile drug. Materials and Methods: DLX microspheres were prepared by simple emulsification phase separation technique using chitosan as carrier and glutaraldehyde as a cross-linking agent. Microspheres prepared were coated with eudragit L-100 using an oil-in-oil solvent evaporation method. Eudragit L-100was used as enteric coating polymer with the aim to release the drug in small intestine The microspheres prepared were characterized by particle size, entrapment efficiency, swelling index (SI), mucoadhesion time, in vitro drug release and surface morphology. A 32 full factorial design was employed to study the effect of independent variables polymer-to-drug ratio (X1) and stirring speed (X2) on dependent variables, particle size, entrapment efficiency, SI, in vitro mucoadhesion and drug release up to 24 h (t24). Results: Microspheres formed were discrete, spherical and free flowing. The microspheres exhibited good mucoadhesive property and also showed high percentage entrapment efficiency. The microspheres were able to sustain the drug release up to 24 h. Conclusion: Thus, the prepared enteric coated mucoadhesive microspheres may prove to be a potential controlled release formulation of DLX for oral administration. PMID:24167786

Credit scoring analysis using kernel discriminant

NASA Astrophysics Data System (ADS)

Widiharih, T.; Mukid, M. A.; Mustafid

2018-05-01

Credit scoring model is an important tool for reducing the risk of wrong decisions when granting credit facilities to applicants. This paper investigate the performance of kernel discriminant model in assessing customer credit risk. Kernel discriminant analysis is a non- parametric method which means that it does not require any assumptions about the probability distribution of the input. The main ingredient is a kernel that allows an efficient computation of Fisher discriminant. We use several kernel such as normal, epanechnikov, biweight, and triweight. The models accuracy was compared each other using data from a financial institution in Indonesia. The results show that kernel discriminant can be an alternative method that can be used to determine who is eligible for a credit loan. In the data we use, it shows that a normal kernel is relevant to be selected for credit scoring using kernel discriminant model. Sensitivity and specificity reach to 0.5556 and 0.5488 respectively.

Correlation and classification of single kernel fluorescence hyperspectral data with aflatoxin concentration in corn kernels inoculated with Aspergillus flavus spores.

PubMed

Yao, H; Hruska, Z; Kincaid, R; Brown, R; Cleveland, T; Bhatnagar, D

2010-05-01

The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillus flavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn ears in the field with toxigenic A. flavus spores. The kernel fluorescence emission data were taken with a fluorescence hyperspectral imaging system when corn kernels were excited with ultraviolet light. Raw fluorescence image data were preprocessed and regions of interest in each image were created for all kernels. The regions of interest were used to extract spectral signatures and statistical information. The aflatoxin contamination level of single corn kernels was then chemically measured using affinity column chromatography. A fluorescence peak shift phenomenon was noted among different groups of kernels with different aflatoxin contamination levels. The fluorescence peak shift was found to move more toward the longer wavelength in the blue region for the highly contaminated kernels and toward the shorter wavelengths for the clean kernels. Highly contaminated kernels were also found to have a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also noted that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green regions. The correlation coefficients of determination, r(2), was 0.72 for the multiple linear regression model. The multivariate analysis of variance found that the fluorescence means of four aflatoxin groups, <1, 1-20, 20-100, and >or=100 ng g(-1) (parts per billion), were significantly different from each other at the 0.01 level of alpha. Classification accuracy under a two-class schema ranged from 0.84 to 0.91 when a threshold of either 20 or 100 ng g(-1) was used. Overall, the results indicate that fluorescence hyperspectral imaging may be applicable in estimating aflatoxin content in individual corn kernels.