Solid Matrix Material Research Articles

A reliable and accurate procedure for preparing low-activity efficiency calibration standards for germanium gamma-ray spectrometers

An empirical procedure is described which is readily capable of producing reliable and accurate efficiency calibration sources of low activity for high-resolution γ-ray spectrometers. Known activities of a multiisotopic solution are adsorbed onto a mixture of cation and anion-exchange resins and chromatographic-grade cellulose. The dried powder that results can be mixed with any desired solid natural matrix material to produce a homogeneous, extended geometry, efficiency calibration source. Results are presented which enable the method to be critically evaluated.

Analysis of Steady Compaction Waves in Porous Materials

A two-phase continuum mixture model is used to analyze steady compaction waves in porous materials. It is shown that such a model admits both subsonic and supersonic steady compaction waves in response to a piston-driven boundary condition when a Tait equation is used to describe a solid matrix material and a generic static compaction relation is used to describe collapse of the matrix. Parameters for the Tait equation are chosen to match shock and compaction wave data. The model is able to predict compaction wave speed, final pressure, and final volume fraction in porous HMX. The structure of the compaction wave is also studied. A shock preceding the compaction wave structure is predicted for compaction waves travelling faster than the ambient sound speed of the solid. For subsonic compaction waves no leading shock is predicted. The compaction zone length is studied as a function of initial volume fraction, piston velocity, and compaction viscosity.

Analytical applications of neutron depth profiling

Using a low-energy neutron beam as an isotopic probe, neutron depth profiling (NDP) provides quantitative depth profiles in nearly all solid matrix materials. Several of the light elements, such as He, Li, B, and N can be nondestructively analyzed by NDP. The information obtained using NDP is difficult if not impossible to determine by non-nuclear techniques. As a result, NDP is used collaboratively with techniques such as SIMS, RBS, FTIR, PGAA, and AES. Profiles measured by NDP are given for semiconductor and optical processing materials, and light weight alloys. Improvements in the technique are discussed with emphasis on the use of intense cold neutron beams.

Isotachophoretic analysis of pharmaceutic formulations with different matrices: Determination of nicotinic acid in capsules, tablets, dragees, ointments and tinctures

The selectivity of isotachophoresis is investigated concerning the quantitative determination of an anionic agent in a variety of pharmaceutic application forms with different matrices. As a result, no interferences caused by matrix components were observed in any case. Therefore sample pretreatment can be neglected. The simultaneous quantitation of other anionic constituents, present in the formulations, is possible. The method is evaluated by other analytical characteristics besides selectivity, like precision, accuracy and time of analysis. The contributions of aliquotation and isotachophoretic measurement to the total error were determined by analysis of variance. Systematic errors, due to adsorption of the analyte on solid matrix material were examined by standard addition. The results of the analytical characteristics indicate the excellent applicability of isotachophoresis for the routine analysis of anionic analytes in pharmaceutic preparations

Porous kaolinite bead: A novel but economical solid support material for biomass in fluidised bed technology

Porous kaolinite beads were prepared by mixing kaolinite with various proportions of rice hull ash (RHA) and heating in a furnace at 800 °C for five hours. Those with 10 to 60% (w/w) RHA were very porous and had good mechanical strength. The raw materials were inexpensive and their preparation relatively simple, therefore these porous kaolinite beads would be an excellent solid support matrix material for the utilization of biomass in biological fluidised bed (BFB) processes.

Porosity Effects in Polycrystalline Graphite

Thermal and physical properties of a series of porous, polycrystalline graphites have been measured. The solid matrix material was characterized by X‐ray diffraction measurements of crystallite size, interplanar spacing, and anisotropy. The pore structure was examined using electron micrography, porosimetry, permeability, and helium density measurements. Thermal and electrical conductivities and elastic modulus measurement results were correlated with the fractional porosities of the graphites.

Waterflood Behavior of High Viscosity Crudes in Preserved Soft and Unconsolidated Cores

Abstract An extensive field and laboratory experimental program was carried out to compare the waterflood behavior of carefully preserved soft and unconsolidated cores with measurements on the same cores after extraction. Results obtained from using idealized consolidated and unconsolidated porous media in which wettability could be carefully controlled were contrasted with the preserved core data. The controlled tests on idealized porous media investigated the effect of wettability, flood rate, core length, core permeability and consolidation on the displacement of high viscosity oils. It was concluded from these studies that waterfloods are more favorable when carried out with crude oil in preserved soft and unconsolidated cores than with the same cores after they have been extracted and resaturated. Waterfloods are usually more favorable when carried out with crude oil in extracted soft and unconsolidated cores than with refined oil of the same viscosity in the same cores. The less favorable behavior of extracted soft and unconsolidated cores compared to preserved cores is due to alteration of the core by extraction. Preserved cores saturated with native water and oil should be used for laboratory displacement experiments because they more accurately reflect true reservoir behavior. INTRODUCTION The demand for low gravity crude oil created by refinery modernization has focused attention on increasing the production of this viscous crude oil. Billions of barrels are in place in fields that are depleted, or nearly depleted, by primary production mechanisms. Since low gravity reservoirs are relatively recent, geologically, the solid matrix material is usually soft and unconsolidated sand. Such formations are also characterized by a high clay content. Evaluation of sophisticated oil recovery processes with the associated high capital investments has increased the demand for special core analysis tests on material from these soft and unconsolidated sand reservoirs. Data in this paper have resulted from an extensive field and laboratory experimental program. The initial objective was to provide soft and unconsolidated sand cores for laboratory measurements with as little alteration as possible from their reservoir condition. A secondary objective was to compare the waterflood behavior of these carefully preserved cores with measurements on the same cores after they had been extracted and resaturated. When the comparison showed markedly different behavior the final objective was to attempt to explain the difference by making measurements on idealized porous media free of clay in which initial wettability could be carefully controlled. EXPERIMENTS MATERIALS Core Material The preserved cores used in this study were obtained with as little alteration as possible from their reservoir conditions. Special techniques were developed to satisfy this objective. The cores were cut with native crude whenever the crude had the necessary properties to satisfy the minimum drilling fluid requirements. A pure hydrocarbon chromatographic tracer was added to the crude to provide a simple, safe and inexpensive method to distinguish between oil filtrate and formation oil. Details of the tracer technique used in this study and the procedures used to handle and process the soft, unconsolidated cores have been published.1 The core samples were then preserved and packaged at the well site with a dip-applied strippable plastic, or by using a rubber sleeve from a rubber-sleeve core barrel. The final step was to insure that the. carefully taken and preserved samples were not altered by processing in the laboratory. Some soft and poorly consolidated sands were carefully shaped in the lab and encased in a protective mounting without disturbing their three-dimensional integrity. Many samples were so poorly consolidated that they literally flowed from the package when the seal was broken. A technique was developed to obtain cylindrical plugs from these samples by using liquid nitrogen as the drilling fluid in a conventional core-drill, drill-press assembly. The idealized porous media consisted of sintered rods of Alundum RA 139, outcrop sandstone identified as Alhambra sandstone and packs of No. 130 Nevada sand. This sand is 95 per cent 140–200 mesh. (Physical properties of these porous media with those representative of preserved cores are in Table 1.) The natural cores and most of the idealized porous media were 1 1/2-in. in diameter and 3-in. long. The samples used to study the effect of core length were 1 1/2-in. in diameter and 12-in. long.

Hydrogen Abstraction from Hydrocarbons by Methyl Radicals from the Photolysis of Methyl Iodide in Solid Nitrogen

Abstract : CH3I was photolyzed at 20 K in solid matrix materials, N2, Kr, and Xe, containing hydrocarbons (C2H6 or (CH3)3CH) or deuterated hydrocarbons (CD4, CH3CD3, or (CH3)3CD). H abstraction was studied by infrared detection of CH4 and CH3D. In the solid, the abstraction products can be attributed to CH3 radicals with an effective te perature in the range 1000 - 3000 K. The products obtained from photolysis of CH3I with C2H6 present as well as those from photolysis of C2H5I in N, indicated that about 85% of the reactions probably occurred within the cage at the site f photon absorption. These studies provided information concerning the dissipation of the energy of a hot radical constrained within a reactive cage. (Author)