The application of soft X-ray microscopy to the in-situ analysis of sporopollenin/sporinite in a rank variable suite of organic rich sediments

Soft X-ray imaging and carbon near edge absorption fine structure spectroscopy (C-NEXAFS) has been used for the in-situ analysis of sporinite in a rank variable suite of organic rich sediments extending from recent up to high volatile A bituminous coal. The acquisition of chemically based images (contrast based on the 1s - 1{pi}* transition of unsaturated carbon), revealed a homogeneous chemical structure in the spore exine. C-NEXAFS microanalysis indicates chemical structural evolution in sporopollenin/sporinite with increases in maturation. The most significant change in the C-NEXAFS spectrum is an increase in unsaturated carbon, presumably aromatic, with rank. The rate of aromatization in sporinite exceeds that of the surrounding vitrinite. Increases in the concentration of unsaturated carbon are compensated by losses of aliphatic and hydroxylated aliphatic carbon components. Carboxyl groups are present in low and variable concentrations. Absorption due to carboxyl persists in the most mature specimen in this series, a high volatile A rank coal. The reactions which drive sporopollenin chemical structural evolution during diagenesis presumably involve dehydration, Diels-Alder cyclo-addition, and dehydrogenation reactions which ultimately lead to a progressively aromatized bio/geopolymer

Recoil Polarization for Delta Excitation in Pion Electroproduction

We measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q^2=1.0 (GeV/c)^2, obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes. We performed a nearly model-independent multipole analysis and obtained values for Re(S1+/M1+)=-(6.84+/-0.15)% and Re(E1+/M1+)=-(2.91+/-0.19)% that are distinctly different from those from the traditional Legendre analysis based upon M1+ dominance and sp truncation.Comment: 5 pages, 2 figures, for PR

Organic or organometallic template mediated clay synthesis

A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays

Magnetic resonance imaging of solvent transport in polymer networks

The spectroscopic technique of magnetic resonance imaging (MRI) has recently provided a new window into transport of solvents in polymer networks. Diffusion of solvent as a rate-controlling phenomenon is paramount to understanding transport in many important industrial and biological processes, such as upgrading fossil fuels, film casting and coating, development of photoresists, design of drug-delivery systems, development of solvent resistant polymers, etc. By MRI mapping the migration of solvent molecules through various polymer specimens, researchers Robert Botto and George Cody of Argonne National Laboratory, with support from the Division of Chemical Sciences at DOE, were able to characterize and distinguish between different modes of transport behavior associated with fundamentally different types of polymer systems. The method was applied to rubbers, glassy polymers, and coals. In polymers shown to undergo a glass transition from a rigid to rubbery state, a sharply defined solvent front was observed that propagated through specimens in the manner of a constant velocity shock wave. This behavior was contrasted with a smooth solvent concentration gradient found in polymer systems where no glass transition was observed. The results of this analysis have formed the basis of a new model of anomalous transport in polymeric solids and are helping to ascertain fundamental information on the molecular architectures of these materials

Recent advances in magnetic resonance microscopy to the physical structure characterization of carbonaceous and inorganic materials

Magnetic resonance microscopy (MRM) techniques have been employed to study the molecular architectures and properties of structural polymers, fossil fuels, microporous carbons and inorganic catalysts

NMR imaging: A chemical' microscope for coal analysis

This paper presents a new three-dimensional (3-D) nuclear magnetic resonance (NMR) imaging technique for spatially mapping proton distributions in whole coals and solvent-swollen coal samples. The technique is based on a 3-D back-projection protocol for data acquisition, and a reconstruction technique based on 3-D Radon transform inversion. In principle, the 3-D methodology provides higher spatial resolution of solid materials than is possible with conventional slice-selection protocols. The applicability of 3-D NMR imaging has been demonstrated by mapping the maceral phases in Utah Blind Canyon (APCS {number sign}6) coal and the distribution of mobile phases in Utah coal swollen with deuterated and protic pyridine. 7 refs., 5 figs

NMR spectroscopy and imaging of macerals in Argonne premium coals

Macerals that have been separated from two high-volatile bituminous coals from the Argonne Premium Coal Sample Program are surveyed using chemical and NMR spectroscopic techniques. Quantitative aspects of the method are discussed. Alkylation using {sup 13}C enriched methyl iodide followed by solid {sup 13}C NMR analysis was used to determine the concentrations of acidic OH and CH sites in these macerals. Also, the first successful application of nuclear magnetic resonance imaging (MRI) for spatially mapping chemically distinct regions within a Utah coal has been demonstrated. 15 refs., 5 figs., 2 tabs

Soft x-ray microanalysis and microscopy: A unique probe of the organic chemistry of heterogeneous solids

STXM and C-NEXAFS (carbon near edge absorption micro-spectroscopy) microanalysis were used to analysis the microchemistry of cokes and highly carbonaceous materials. The issue of molecular orientation is addressed by using the intrinsic polarization of the x-ray beam at X1A beamline at NSLS

Quantitative MRI (magnetic resonance imaging) measurement of binder distributions in green-state ceramics

Nuclear magnetic resonance imaging techniques were investigated for nondestructive evaluation of injection molded structural ceramics. Several injection-molded Si{sub 3}N{sub 4} test bars, fabricated using different mixing and molding parameters, were imaged by 2-D back-projection {sup 1}H NMR techniques. The gray scale intensities of the images were correlated with the data obtained by destructive testing. The correlation studies indicate that changes in the organic concentration to a level of {plus minus} 0.5 wt % can be detected with NMR. It is possible, with these techniques, to monitor the chemical changes that occur at various stages of ceramic processing and use this information to improve the ceramic processing and reliability. 8 refs., 1 tab

Three-dimensional nuclear magnetic resonance and x-ray microtomographic imaging of composite materials

This paper presents a new-three-dimensional nuclear magnetic resonance (NMR) imaging technique for nondestructive evaluation of green-state ceramic composite materials. The technique is based on a 3-D backprojection protocol for data acquisition combined with a Radon reconstruction technique. Particularly for NMR of solid materials, this imaging protocol can provide higher three dimensional spatial resolution than is possible with commonly applied slice-selection protocols. The applicability of this 3-D NMR imaging technique was demonstrated using whisker-reinforced Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} ceramic composites. While NMR is a sensitive and unique method for spatial discrimination of chemical properties (e.g., organic distributions), x-ray CT is a sensitive and proven technique for determining variations in density (i.e., voids and inclusions) within an object. The complementary nature of these two techniques was shown by imaging a piece of green ceramic composite material by both NMR and x-ray microtomography techniques