Assessment of elastic parameters of human skin using dynamic elastography

Sonoelastography and transient elastography are two ultrasound-based techniques that facilitate noninvasive characterization of the viscoelastic properties of soft tissues by investigating their response to shear mechanical excitation. Young's modulus is the principle assessment parameter. Because it defines local tissue stiffness, it is of major interest for the medical imaging and cosmetic industries as it could replace subjective palpation by yielding local, quantitative information. In this paper, we describe a new high-resolution device capable of measuring local Young's modulus in very thin layers (1-5 mm) and devoted to the in vivo evaluation of the elastic properties of human skin. It uses an ultrasonic probe (50 MHz) for tracking the displacements induced by a 300 Hz shear wave generated by a ring surrounding the transducer. The displacements are measured using a conventional cross-correlation technique between successive ultrasonic back-scattered echoes. First, this noninvasive technique has been experimentally proven to be accurate for investigating elasticity in different skin-mimicking phantoms. Second, data were acquired in vivo on human forearms. As expected, Young's modulus was found to be higher in the dermis than in the hypodermis and other soft tissues.     

The interaction of IgE antibody with human alveolar macrophages and its participation in the inflammatory processes of lung allergy

After the initial observation that human and animal mononuclear phagocytes can be activated into specific killer cells against larvae of the parasite Schistosoma mansoni by seric IgE antibody from infected patients, a possible interaction of IgE with human alveolar macrophages in asthmatic patients was investigated. In vitro, alveolar macrophages from non-atopic individuals can bind monoclonal IgE molecules, as well as IgE antibody from the serum of patients with respiratory allergy. A subsequent contact with anti-IgE antibody or with the specific allergen induces the extracellular release of a variety of mediators, such as lysosomal enzymes, neutral proteases, or superoxide anion. Due to the presence of allergen-specific IgE antibody on the macrophage surface in situ, the same results were obtained in vitro with freshly purified alveolar macrophages from allergic patients. Disodium cromoglycate, corticosteroids, or beta-adrenergic stimulants are strong inhibitors of this specific exocytosis of physiological mediators. The atopic cells formed rosettes with allergen-coated erythrocytes at 4 degrees C, except after pretreatment with aggregated monoclonal IgE or with the allergen.     

Primary processes of the thermal degradation of HET acid containing unsaturated polyester cured with styrene

The primary processes of thermal degradation of 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic (HET) group containing unsturated polyesters cured with styrene were investigated. DTA traces in nitrogen atmosphere showed a much more pronounced endothermic reaction as the chlorine content in the unsaturated polyester resin decreased. This could be associated to the unzipping of the polystyrene units which is interfered by hexachlorocyclopentadiene ejected during degradation. Actually the styrene formation is prevented in a certain range of temperature due to the interaction with hexachlorocyclopentadiene. This was proved by on-line mass spectroscopic analysis of the degrading polymer.     

X-ray Absorption Spectroscopy of CuO2 Chains

The electronic structure of various edge-shared chain compounds A_1–x CuO₂ (A=Ca,Sr,Ba) was studied by O-K and Cu-L₃ x-ray absorption spectroscopy and exact diagonalizations techniques. The doping-dependent behaviour in these chains differs from that of conventional 2D Cu-O networks of cornershared CuO₄ plaquettes due to the much smaller inter-plaquette hybridisation. This results in different final states in the Cu-L₃ spectra and a strong reduction in the dynamic spectral weight transfer from the upper Hubbard band to the low energies in the O-K spectra. The spectra can be used to read-off the Cu valency.     

CO2 LASER PHOTOACOUSTIC SPECTROSCOPY AND ABSOLUTE ABSORPTION COEFFICIENTS OF SHORT CHAIN SATURATED FATTY ACID VAPOURS

Abstract

A resonant photoacoustic cell, capable of contamination free operation at temperatures above that of the ambient, was constructed and used to determine absolute absorption coefficients of C6:0 (hexanoic) and C8:0 (octanoic) fatty acid vapours at CO₂ laser wavelengths. At atmospheric pressure, the maximum absorption coefficients at the 9R(32) line of the CO₂ laser (1085.77cm^?1) are 8.0 atm^?1 cm^?1 (C6:0 at 332K) and 8.9 atm^?1 cm^?1 (C8:0 at 342 K).