Multiple focal nodular hyperplasia syndrome: diagnosis with dynamic, gadolinium-enhanced MRI

We present a rare case of multiple focal nodular hyperplasia (FNH) with greater than 20 FNH lesions and coexistent liver hemangiomata. Particular attention is paid to the MRI characteristics of this disease process and the features of "multiple FNH syndrome" are discussed.     

Vortex lattice transitions in YNi2B2C

We have performed extensive small-angle neutron scattering (SANS) diffraction studies of the vortex lattice in single crystal YNi₂B₂C for B‖c. High-resolution SANS, combined with a field-oscillation vortex lattice preparation technique, allows us to separate Bragg scattered intensities from two orthogonal domains and accurately determine the unit cell angle, β. The data suggest that upon increasing field there is a finite transition width where both low- and high-field distorted hexagonal vortex lattice phases, mutually rotated by 45°, coexist. The smooth variation of diffracted intensity from each phase through the transition corresponds to a redistribution of populations between the two types of domains.     

A Convenient One-Step Synthesis of 2-Hydroxy-1,3,5-Benzenetricarbaldehyde

The hexamethylenetetramine/trifluoroacetic acid system was demonstrated to be capable of introducing three aldehyde groups into the phenol molecule. Facile, one-step procedures were developed for the preparation of hitherto difficult to synthesize 2-hydroxy-1,3,5-benzenetricarbaldehyde starting from either phenol or 4-hydroxybenzaldehyde. New pKa measurements showed 2-hydroxy-1,3,5-benzenetricarbaldehyde to be an acid stronger than previously reported.     

Transformations in the medium-range order of fused silica under high pressure

Molecular dynamics simulations of fused silica at shock pressures reproduce the experimental equation of state of this material and explain its characteristic shape. We demonstrate that shock waves modify the medium-range order of this amorphous system, producing changes that are only clearly revealed by its ring size distribution. The ring size distribution remains practically unchanged during elastic compression but varies continuously after the transition to the plastic regime.     

Association of humic acid with metal (hydr)oxide-coated sands at solid-water interfaces

Mineral-bound humic acid (HA) can significantly modify the physicochemical properties of the mineral surfaces and vice versa, thereby influencing the fate and transport of organic pollutants in the subsurface. The effect of various mineral surfaces on the adsorption-desorption of dissolved bulk, terrestrial HA was evaluated using three model sorbents [uncoated, alpha-FeO(OH)-coated, and Al2O3-coated sands] at two equilibrium pH values. The results of SEM/EDS and XPS analyses revealed relatively uniform and stable metal (hydr)oxide coatings on quartz surface and the presence of the HA coating. Strong hysteresis effects were observed for both metal (hydr)oxide-coated sands whereas a weaker hysteresis effect was observed for uncoated sand, suggesting that the adsorption-desorption of HA to model sorbents is dependent on the affinity of chemical interactions between the HA and surface composition of model sorbents. Adsorption of HA molecules onto metal (hydr)oxide-coated sands can be attributed to ligand exchange for lower molecular weight (MW) HA fractions and hydrophobic interaction for higher MW HA fractions, illustrating that both kinetic and fractional adsorption-desorption of HA subcomponents are important considerations.     

Flow phenomena in floppy tubes

Collapsible tubes, which occur all over the body, have unique properties from the point of view of both physics and physiology. A brief review is attempted of first the basic observable properties, followed by simple theory to explain the steady-flow aspects and an overview of the somewhat more complex theories for unsteady flow, in particular the flow-induced oscillations. The experimental evidence from laboratory studies is reviewed with particular emphasis on the dynamical system aspects. A final section looks at the current position and prospects.     

The interstitial structure of vitreous silica

A careful analysis of gas solubility data provides a unique tool for characterizing glass network geometry. The density of interstitial (solubility) sites in vitreous silica and its crystalline analog, high cristobalite, was reviewed. Close inspection of high cristobalite indicates that there are eight solubility sites per unit cell giving a bulk density of 2.34 × 10²² sites/cm³. A statistical thermodynamic analysis of experimental solubility data for helium and neon in high cristobalite correlates with this calculated value. Correcting this value for the slightly lower bulk density of vitreous silica gives an estimated density of solubility sites in vitreous silica of 2.22 × 10²² sites/cm³. Literature data for solubility site density (obtained from the same statistical thermodynamic analysis) depend strongly on the dissolved gas species. This implies a statistical distribution of effective site diameters. The probability distribution function is adequately represented as log-normal.     

Enhanced spectrum matching of mixed mass spectra by means of quality factors

A system of computer programs for recognizing impure or mixed spectra was assembled that provided automatic subtraction of reference mass spectra from a mixed spectrum. The software was 99% successful in recognizing pure spectra for the cases tested. Subtractions were done on mixed spectra in 70% of the cases tested. Spectrum subtraction enhanced the ability of the matching program to match components of a multicomponent mixture correctly, whereas quality factors were a great aid in the evaluation of the overall match validity.