Amount Of Matrix Material Research Articles

A Compact Gas-Cooled Fast Reactor with an Ultra-Long Fuel Cycle

In an attempt to allow nuclear power to reach its full economic potential, General Atomics is developing the Energy Multiplier Module (EM2), which is a compact gas-cooled fast reactor (GFR). The EM2augments its fissile fuel load with fertile materials to enhance an ultra-long fuel cycle based on a “convert-and-burn” core design which converts fertile material to fissile fuel and burns it in situ over a 30-year core life without fuel supplementation or shuffling. A series of reactor physics trade studies were conducted and a baseline core was developed under the specific physics design requirements of the long-life small reactor. The EM2core performance was assessed for operation time, fuel burnup, excess reactivity, peak power density, uranium utilization, etc., and it was confirmed that an ultra-long fuel cycle core is feasible if the conversion is enough to produce fissile material and maintain criticality, the amount of matrix material is minimized not to soften the neutron spectrum, and the reactor core size is optimized to minimize the neutron loss. This study has shown the feasibility, from the reactor physics standpoint, of a compact GFR that can meet the objectives of ultra-long fuel cycle, factory-fabrication, and excellent fuel utilization.

Combinatorial Optimization of Multiple MALDI Matrices on a Single Tissue Sample Using Inkjet Printing

Taking advantage of the drop-on-demand capabilities of inkjet printing, the first example of a single tissue being used as a substrate for preparing combinatorial arrays of different matrix-assisted laser desorption/ionization (MALDI) matrices in multiple concentrations on a single chip is reported. By varying the number of droplets per spot that were printed, a gradient array of different amounts of matrix material could be printed on a single chip, while the selection of matrices could be adjusted by switching different matrix materials. The result was a two-dimensional array of multiple matrices on a single tissue slice, which could be analyzed microscopically and by MALDI to elucidate which combination of matrix and printing conditions offered the best resolution in terms of spot-to-spot distance and signal-to-noise ratios for proteins in the recorded MS spectra. This combinatorial approach enables the efficient optimization of possible matrices in an organized, side-by-side array format, which can particularly be useful for the detection of specific protein markers.

Tensile properties of kenaf/unsaturated polyester composites filled with a montmorillonite filler

AbstractKenaf/unsaturated polyester composites filled with montmorillonite (MMT) filler were produced. Overall, the study showed that, for samples with kenaf filler only, the strength properties decreased as the kenaf filler loading was increased from 40 to 60%. The increase in the kenaf filler loading reduced the amount of matrix material. This subsequently lowered the ability of the sample to absorb energy or distribute stress efficiently. However, with MMT, the tensile properties improved because of the high aspect ratio and surface area of the MMT. The study of the effect of kenaf filler size on the tensile properties showed that the samples with the smallest size (74 μm) displayed the lowest tensile properties compared to the larger ones. This was attributed to the agglomeration of the kenaf fillers. The addition of MMT resulted in an overall increase in the tensile strength of the composites compared to those without MMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Application of internal universal calibration for determination of fully dissociated species in capillary electrophoresis using indirect UV detection and electrokinetic injection

Although the electrokinetic injection suffers from quantitation problems arising from mobility and matrix bias, the application of electrokinetic injection and indirect photometric detection may provide a very simple, sensitive and universal determination of fully dissociated components. In this work a survey of the possibilities of quantitative analysis using EK injection with indirect UV detection is given and a simple procedure (internal universal calibration) for accurate quantitative determination of traces using EK injection is proposed. It was shown that the thiosulfate as an internal universal standard (IUS) can be applied for quantitative determination of fully dissociated analytes (e.g. Br −, Cl −, NO 2 −, NO 3 −, SO 4 2−, S 2O 3 2−) whose mobilities (migration times) do not differ from the mobilities of monitoring ion (chromate), counter-ion (potassium) and IUS with more than 10%. The proposed calibration procedure provides concentration data, which deviate generally less than 5% extent from the actual true values. The validity and the applicability of the method was studied in the analysis of samples containing different amount of matrix material.

High precision determination of uranium in ore by gamma-ray spectrometry

A new approach for the determination of elemental uranium in uranium bearing ore, using high resolution γ-ray spectrometry, was applied. Using a variant of the enrichment technique an agreement of better than 1% has been obtained between γ-ray measurement results and a certified value obtained by other analytical methods. For the calibration of the γ-ray spectrometer uranium reference samples have been used which are made available jointly in Europe and the USA as Certified Reference Materials for Gamma-Ray Spectrometry (EC NRM 171 and NBS SRM 969, respectively). The measured ore has been put in a special designed container which ensured in all directions seen from the radiation window an uniform degree of infinite thickness of about 95%. The results can be taken as an example for the applicability of γ-ray spectrometry when high accuracy is required and under conditions were homogeneously distributed elemental uranium is embedded in larger amount of matrix material.

Interfacial adhesion between ionic copolymers and high‐modulus surface‐treated carbon fibers

AbstractHigh‐modulus carbon‐fiber‐reinforced thermoplastic composites typically fail at the interface due to poor adhesion between fiber and matrix. To increase interfacial strength, the research described herein focuses on modifying the fiber surface (via high‐temperature acid treatment or zinc electrolysis) to facilitate chemical functional groups on the fiber that might increase fiber‐matrix inter‐actions. The thermoplastic matrix materials used in this study were random copolymers of ethylene and methacrylic acid in which the carboxyl groups in the methacrylic acid segments were neutralized with either sodium or zinc counterions. Mechanical tests were performed to determine the macroscopic effects of fiber pretreatment on the ultimate mechanical properties of the composites. Fabrication was designed such that fiber‐matrix separation provides the dominant contribution to mechanical gracture. Composites containing fibers treated with nitric acid, or a mixture of nitric and sulfuric acids exhibit a 20 to 25 percent increase in transverse (tensile) fracture stress relative to composites fabricated with as‐received fibers. Scanning electron microscopy of the fiber‐matrix interface at fracture allows one to “zoom‐in” and obtain qualitative details related to adhesion. Fracture surface micrographs of the above‐mentioned acid‐treated fiber‐reinforced composites reveal an increase in the amount of matrix material that adhered to the fiber surface relative to the appearance of the fracture surface of composites fabricated with as‐received fibers. The presence of acid functionality in the matrix, rather than the divalent nature of the zinc counterions, produces the largest relative enhancement of transverse (tensile) fracture stress in the above‐mentioned composites containing surface‐treated carbon fibers.

Correlation between interfacial interactions and internal stresses in filled high density polyethylene

The stress relaxation and the creep behaviour of high density polyethylene (HDPE) filled with glass fibres, clay (plate-like particles) or CaCO3 (particles with irregular shape) were measured in uniaxial extension at room temperature. It was observed that the addition of filler increased the internal stress level, as evaluated from stress relaxation data. This increase was larger than the corresponding increase in the (short-term) elastic modulus. This behaviour may be attributed to a reduced macromolecular mobility in the matrix material close to the filler surface, i.e. to formation of an interphase region in the HDPE-matrix. From the internal stress values, the thickness of this interphase region around each filler particle was estimated, assuming a uniform coverage of the particles. It was suggested that the amount of matrix material with reduced mobility (or the thickness of the interphase region) reflected the degree of adhesion between the filler and HDPE. The change in the internal stress level due to the incorporation of different fillers, which were surface treated in some cases, was also consistent with the observed creep behaviour.

Prediction of the viscoelastic properties of granular composites. Dynamic characteristics of ABS plastics

Among the commonest types of polymer composites are the impact polystyrenes (IPS) and the related ABS plastics [1, 21. Structurally they are granular composites with a glassy matrix (polystyrene in IPS and SAN copotymer in ABS plastics). The shape of the inclusions is almost spherical. Strong contact at the phase interfaces is achieved by chemical grafting of the polystyrene or SAN macromolecules to the rubber. The elastomeric phase inclusions in the IPS contain polystyrene occlusions in the form of very small granules with interlayers of rubber between them. In ABS plastics the elastomeric phase inclusions are smaller in size than in IPS (up to 1 t~m), and under the electron microscope the SAN occlusions within the inclusions are less clearly distinguishable [1 ]. At the same time, it may be assumed that the elastomeric phase of the ABS plastic also contains a significant amount of matrix material, i.e., SAN, since grafting prevents the complete segregation of the components.

Factors influencing the performance of sintered carbides under arduous conditions of rolling contact

Using an accelerated service simulation test the performance of sintered carbides under arduous conditions of unlubricated and elevated temperature rolling contact has been assessed and compared with that of conventional ball bearing materials and other potentially suitable wear resistant materials. Metallurgical and electronmicroscopical investigation of tested specimens has provided fine-scale information of use in the elucidation of failure mechanisms and their controlling factors. Under the conditions of test, sintered tungsten carbide was superior to the other materials tested unlubricated at both ambient and elevated temperature. Grain size of the carbide as well as the amount of matrix material can have a considerable influence on performance and on the wear mechanism of failure.

Electron microscopic study on gliosome formation in postnatal development of spinal cord in the cat.

AbstractThe CNS of cats including newly‐born, 2 day‐, 4 day‐, 10 day‐, 18 day‐, 3 week‐, 6 week‐ and 3 month‐old kittens and adults, were fixed by perfusion from the aorta with 1% osmium tetroxide in acetate‐veronal buffer, or with 2.5 to 3% glutaraldehyde or 4% formaldehyde in phosphate buffer and retreatment with osmium tetroxide after removal. The astrocytes in the intermediolateral horn of the thoracic spinal cord and in the neighboring lateral funiculus were examined under the electron microscope. The astrocytic mitochondria are larger than the neuronal ones at birth. They have a finely granular matrix and dispersed cristae mitochondriales. During the first 4 to 10 days after birth many of the astrocytic mitochondria enlarge, with an increase in the amount of matrix material and its crystallization into a filamentous array, forming “gliosomes.” Within two to three weeks, a bundle of crystalline filaments with a regular periodicity are formed in the matrix. The rough surfaced endoplasmic reticulum seems to be closely associated with the processes of gliosome formation. Namely, cisterane of the rough endoplasmic reticulum first accompany the growing mitochondria, then lose ribosomes on their proximal membranes, and finally change into vesicles of the smooth endoplasmic reticulum around the gliosomes and gliofilaments. The possible significance of these structural changes is discussed.

Paper 17: Study of Sintered Carbides and Surface-Treated Materials for Unlubricated and Elevated Temperature Rolling Elements

Materials and surface treatments potentially suitable for unlubricated and elevated temperature rolling bearings have been compared, wear resistance being assessed by loss of weight under unlubricated conditions. Tungsten carbide was superior to other materials tested. Grain size of the tungsten carbide and the amount of matrix material can have a considerable effect on performance. Use of solid film lubricants can eliminate or reduce wear. Soft nitriding can also be beneficial. Metallurgical investigations of some selected failed specimens have been carried out.