Histologic and Rheologic Characterization of Vocal Fold Scarring

Scarring of the vocal fold causes considerable dysphonia and presents significant treatment challenges. A rabbit model was developed to investigate the histologic ultrastructure and rheologic properties of the scarred vocal fold lamina propria. Eleven rabbit larynges were scarred by means of forcep biopsy. Sixty days postoperatively, the rabbits were sacrificed and their vocal folds were harvested. Histological analysis of the scarred and normal lamina propria was completed for collagen, procollagen, elastin, and hyaluronic acid. Linear viscoelastic shear properties of the tissues were also measured, including elastic shear modulus and dynamic viscosity. Compared to normal vocal fold lamina propria, scarred tissues demonstrated significantly less collagen, an increase in procollagen, and a decrease in elastin. Rheologically, both elastic shear modulus and dynamic viscosity were significantly higher for the scarred tissues. Increased stiffness and viscosity do not appear to result from an increase in collagen, but rather appear to be related to the presence of new, disorganized collagen scaffolding. Results are interpreted in terms of the possible role of interstitial proteins in the etiology of increased stiffness and viscosity, which requires further investigation. This animal model should allow for systematic future investigations of vocal fold scarring and its treatment.     

Quasi-Affinity in certain Classes of Operators

The family of operators S + V (, C, Re > 0), where V isan injective S-Volterra operator (that is, [S, V[ = V²) and— A — V^–1 generates a uniformly bounded C₀-semigroup,is studied in the context of similarity and of the weaker quasi-affinityrelation. It is shown that S is similar to S + V for all , C,Re > 1, and is a quasi-affine transform of S + tV for allt 0 and 0 < < 1.     

Inversion of Contrast in Ferroelectric Smectic C Liquid Crystal Displays

Abstract

Contrast inversion has been observed in ferroelectric smectic C liquid crystal displays when multiplexed using a standard two-slot multiplexing scheme. This occurs when the switching response moves from the trailing half of the double pulse to the leading half at relatively high voltages and short time slots. The effect is explained with reference to the voltage-time switching dependency. Some important implications for multiplexing are pointed out.     

A comparison of polymeric materials as pre-concentrating media for use with ATR/FTIR sensing

Polymer-modified ATR-FTIR spectroscopy was investigated to determine its potential suitability for use as an analytical methodology for process stream analysis. The process stream under investigation contains toluene, tetrahydrofuran, ethanol, and acetonitrile in an aqueous matrix. Four polymers, Teflon® AF2400, poly(acrylonitrile-co-butadiene) (PAB), polydimethylsiloxane (PDMS), and poly(styrene-co-butadiene) (PSB), were chosen for study based on partition coefficients measured using a novel automated GC technique. Polymer suitability as pre-concentration media was assessed utilizing analyte/polymer diffusion coefficient data, equilibrium absorbance values, water ingress, and polymer plasticization. PAB displayed the fastest sensing times and enhanced sensitivities. Teflon® AF2400 demonstrated a low water absorption and a low degree of plasticization. Other factors affecting the diffusion rate of analytes were also investigated including molecular size, shape and analyte concentration. This research demonstrated that the choice of pre-concentrating medium is not a trivial issue, being dictated by a combination of sensitivity constraints as well as polymer robustness in real sample matrices.     

Study of the Production of Hydrogen and Light Hydrocarbons by Spark Discharges in Diesel, Kerosene, Gasoline, and Methane

Reforming liquid fuels into hydrogen and light hydrocarbons is desirable for improving the combustion characteristics of the fuels and the production of reducing agents for applications such as the removal of nitrogen oxides. In this study, diesel, kerosene, gasoline and methane were reformed by spark discharges between needle and plate electrodes at room temperature and atmospheric pressure. The gaseous products from liquid fuels comprised 65–70 % hydrogen and 30–35 % light hydrocarbons having two carbon atoms per molecule (i.e., C2s), or three carbon atoms per molecule (i.e., C3s). The product gases were 90 % hydrogen and 10 % C2s in the case of methane reforming. The energy efficiency for the production of gaseous products was highest in the case of gasoline at 3.8 mol/kWh, followed by kerosene, diesel and methane at 3.2, 3.0, and 2.4 mol/kWh, respectively. These results were found to be comparable to those reported by others for the reforming of pure hydrocarbons by plasmas in liquids. The liquid fuels turned black due to the formation of carbonaceous products, some of which could be filtered out as solid carbon particles, but others remained dissolved and imparted color to the treated liquid.     

Generation of novel, potent urotensin-II receptor antagonists by alkylation-cyclization of isoindolinone C3-carbanions

We report a facile alkylation-cyclization reaction involving the isoindolinone C3 position, which resulted in tricyclic derivatives 2 and 10 in 48% and 32% yields, respectively. These novel compounds possess potent urotensin-II receptor antagonist activity.     

Continuous dependence on modeling for nonlinear ill-posed problems

The nonlinear ill-posed Cauchy problem , where A is a positive self-adjoint operator on a Hilbert space H, χ∈H, and h:[0,T)×H→H is a uniformly Lipschitz function, is studied in order to establish continuous dependence results for solutions to approximate well-posed problems. The authors show here that solutions of the problem, if they exist, depend continuously on solutions to corresponding approximate well-posed problems, if certain stabilizing conditions are imposed. The approximate problem is given by , v(0)=χ, for suitable functions f. The main result is that , where C and M are computable constants independent of β and 0<β<1. This work extends to the nonlinear case earlier results by the authors and by Ames and Hughes.     

Fabrication of polymeric replicas of cell surfaces with nanoscale resolution

We report an approach for fabricating biomimetic surface replicas of cells with nanoscale resolution. Fixed cells serve as a template for a two-stage replica molding process. Cast from the template, the impression replica contains a reproduction of cellular topographical features indented into its surface, and cast from the impression replica, the relief replica contains a copy of these features protruding from its surface. Various polymers and cells can be utilized, and scanning electron microscopy, atomic force microscopy, and white light interferometry analyses confirm the replication of nanoscale features. These replicas are useful for investigating cellular function and for biomimetic tissue engineering.     

Relative importance of criteria in multiobjective programming: A cone-based approach

This article develops a convex polyhedral cone-based preference modeling framework for decision making with multiple criteria which extends the classical notion of Pareto optimality and accounts for relative importance of the criteria. The decision maker’s perception of the relative importance is quantified by an allowable tradeoffs between two objectives representing the maximum allowable amount of decay of a less important objective per one unit of improvement of a more important objective. Two cone-based models of relative importance are developed. In the first model, one criterion is designated as less important while all the others are more important. In the second model, more than one criterion may be classified as less important while all the others are considered more important. Complete algebraic characterization of the models is derived and the relationship between them and the classical Pareto preference is examined. Their relevance to decision making is discussed.     

Selective Reflection of Potassium Vapor Nanolayers in a Magnetic Field

The selective reflection of laser radiation from the interface between a dielectric window and the atomic vapors confined in a nanocell of thickness L ≈ 350 nm is used to develop effective Doppler-broadening- free spectroscopy of potassium atoms. A small atomic line width and a relation between the signal intensity and the transition probability allowed us to resolve four lines of atomic transitions responsible for the D1 lines of the ³⁹K and ⁴¹K isotopes. Two groups containing four atomic transitions form in an applied magnetic field upon pumping by radiation with circular polarization σ⁺ or σ^–. Different intensities (probabilities) of transitions for the σ⁺ and σ^– excitations are detected in magnetic field B₀ ≈ A _hfs /μ_B ≈ 165 G (A _hfs is the magnetic dipole constant for the ground state and μ_B is the Bohr magneton). A substantially different situation is observed at B ? B₀, since high symmetry appears for the two groups formed by radiation with circular polarization σ⁺ or σ^–. Each group is the mirror image of the other group with respect to the frequency of the 4²S_1/2–4²P_1/2 transition, which additionally proves the occurrence of the complete Paschen–Back regime of the hyperfine structure at B ≈ 2.5 kG. A developed theoretical model well reproduces the experimental results. Possible practical applications are described. The results obtained can also be applied to the D₁ lines of ⁸⁷Rb and ²³Na.