The reproducibility of the pulsed ultrasound technique for the determination of skin thickness was investigated, using two independent observers. No systematic difference was found and a high correlation was obtained. Studies were also undertaken to validate the pulsed ultrasound technique as a measure of true skin thickness. Skin thickness determined in vitro was found to be greater than when in vivo determinations were made by either the pulsed ultrasound or a xeroradiographic technique, probably due to the release of in vivo tension within the dermis after excision. Skin thickness was found to increase linearly with age up to the age of 20 years and to decrease linearly with age subsequently. Differences in skin thickness between the sexes and in different sites of the body were demonstrated.

The reproducibility of the pulsed ultrasound technique for the determination of skin thickness was investigated, using two independent observers. No systematic difference was found and a high correlation was obtained. Studies were also undertaken to validate the pulsed ultrasound technique as a measure of true skin thickness. Skin thickness determined in vitro was found to be greater than when in vivo determinations were made by either the pulsed ultrasound or a xeroradiographic technique, probably due to the release of in vivo tension within the dermis after excision. Skin thickness was found to increase linearly with age up to the age of 20 years and to decrease linearly with age subsequently. Differences in skin thickness between the sexes and in different sites of the body were demonstrated.

No abstract

The discovery of highly active piezoelectric polymer materials was first reported in 1969. Since then an enormous amount of research work has been conducted, mainly aimed at discovering the structure and properties of these fascinating materials with the further aim of improving their piezoelectric and pyroelectric behaviour. An equally vast amount of literature devoted to applications of these polymers has appeared and even a cursory glance at all this shows that they have been applied as the basis for a wide range of devices. The subject has now reached a degree of maturity and in the nondestructive testing field, there is perhaps a 'niche market' emerging for transducers based on polyvinylidene fluoride and its derivatives. In certain areas such as miniature

We report the sulfonation of surface-initiated polynorbornene with acetyl sulfate to produce ultrathin ionomer films. The complete process consists of exposure of a hydroxyl-terminated self-assembled monolayer (SAM) on gold to a norbornenyl diacid chloride, attachment of Grubbs first generation catalyst, ring-opening metathesis polymerization (ROMP), and sulfonation. Structural and chemical changes in the film upon sulfonation are confirmed by RAIRS, contact angle goniometry, ellipsometry, optical microscopy, and electrochemical impedance spectroscopy. Sulfonation of surface-initiated polynorbornene results in a highly nonuniform surface morphology which can be relaxed to a more uniform film through exposure to dimethyl sulfoxide at room temperature. The sulfonated polynorbornene films have an intermediate surface energy (θ A (H 2 O) ≈ 75°) and a low resistance against proton transport (R f ≈ 1.6 Ω • cm 2 ), which is 6 orders of magnitude lower than that of the original polynorbornene film. The sulfonated films are far more stable than the original polynorbornene films because of a ∼95% diminution of olefin content within the film. Sulfonated poly(butylnorbornene) films were prepared analogously to demonstrate the versatility of this approach toward ionomer films.