No abstract

Parathyroid hormone-related protein (PTHrP) regulates a wide variety of developmental processes. Keratin 14 (K14) promoter-mediated overexpression of PTHrP in the epidermis during development converts the entire murine ventral skin to hairless nipple-like skin. In this report, we characterize the morphology and processes that influence the development of nipple connective tissue. The connective tissue of the nipple displayed increased levels of proteoglycans, and collagen bundles with atypical morphology, as well as increased numbers of mast cells, capillaries, nerve fibers and dermal melanocytes. The unique characteristics of nipple connective tissue were not present until mice reach 3-4 weeks of age. The adult male K14-PTHrP mouse has a less dramatic ventral skin phenotype, and does not manifest a nipple-like dermis. Ovariectomy or orchiedectomy prior to sexual maturity had no impact on the ventral skin of the male or female K14-PTHrP mice, but exposure to androgens in utero repressed many of the nipple-like characteristics in the ventral skin of the female K14-PTHrP mice.

No abstract

Thin films produced by a number of deposition technologies have found many applications over the past few years in a range of sectors of engineering. As the use of such coatings becomes widespread, the need to assess the quality and reliability of these films becomes more important, for both coating suppliers as a means of process monitoring and end users as a means of identifying if the properties of the coating are suitable for the intended application. There are a number of coatings evaluation tests which are used at present by both suppliers and end users as ranking tools and it would be an advantage if such tests could be extended to be used for quality assurance (QA) assessment. An ideal QA test would be nondestructive, rely on readily available equipment, be quick and easy to perform and interpret, nonsubjective, amenable to automation, and of relevance to the intended application. Unfortunately such tests do not exist and it is essential to make the best use of the tests that are available if QA assessment is to be attempted on test coupons which can be coated alongside real components. In tribological applications it is often the hardness of the coating which dictates component performance, provided that the adhesion of the coating to the substrate is sufficient. Thus it would appear that hardness testing and scratch adhesion testing might be useful bases for QA tests. A methodology by which both tests can be used for QA assessment, given a ‘standard’ coating for comparison which shows the required performance in the intended application, is discussed. The inferences which may be drawn about the reasons for deviations from the standard behaviour are discussed and illustrated for PVD titanium nitride films. This has highlighted the fact that suitable QA of the components before coating is essential if the coating quality is to be reliably assessed.

Bacterial cellulose (BC) is an emerging biopolymer with ever-widening uses in the biomedical field due to its purity, mechanical stability, conformability, moisture control, and biocompatibility. In the wet form, its...