Transition from Order to Configurational Disorder for Surface Reconstructions on SrTiO_{3}(111).

There is growing interest in ternary oxide surfaces due to their role in areas ranging from substrates for low power electronics to heterogeneous catalysis. Descriptions of these surfaces to date focus on low-temperature explanations where enthalpy dominates, and less on the implications of configurational entropy at high temperatures. We report here the structure of three members of the n×n (2≤n≤4) reconstructions of the strontium titanate (111) surface using a combination of transmission electron diffraction, density functional theory modeling, and scanning tunneling microscopy. The surfaces contain a mixture of the tetrahedral TiO_{4} units found on the (110) surface sitting on top of octahedral TiO_{5}[] (where [] is a vacant octahedral site), and TiO_{6} units in the second layer that are similar to those found on the (001) surface. We find clear evidence of a transition from the ordered enthalpy-dominated 3×3 and 4×4 structures to a configurational entropy-dominated 2×2 structure that is formed at higher temperatures. This changes many aspects of how oxide surfaces should be considered, with significant implications for oxide growth.

In situ TEM studies of local transport and structure in nanoscale multilayer films.

This paper describes a novel technique for studying structure-transport correlations in nanoscale multilayer thin films. Here, local current-voltage characteristics from simplified magnetic tunnel junctions are measured in situ on cross-sectional transmission electron microscopy (TEM) samples and correlated directly with TEM images of the microstructure at the tunneling site. It is found that local variations in barrier properties can be detected by a point probe method, and that the tunneling barrier height and width can be extracted.

Cutaneous candidosis as a complication of facial dermabrasion.

Cutaneous candidosis is a common skin condition. Facial candidosis is rare. Described herein are three cases of facial candidosis complicating dermabrasion, a previously undescribed condition. Why this may occur, why it is uncommon, and its differential diagnosis and therapy are discussed. The side effects and complications of dermabrasion in general are presented.

The effect of 13-cis retinoic acid on epidermal lysosomal hydrolase activity in Darier's disease and pityriasis rubra pilaris.

Five patients with Darier's disease and 6 patients with pityriasis rubra pilaris were treated with 13-cis-retinoic acid. Extracts of separated epidermis were assayed for extractable protein, lactic dehydrogenase, Cathepsin D, beta glucuronidase and neutral proteinase before beginning therapy and 2, 4 and 8 weeks after therapy had begun. The epidermal extracts from patients with pityriasis rubra pilaris before beginning therapy were similar to extracts from normal control patients. During the course of therapy with 13-cis-retinoic acid, protein extractability, lactic dehydrogenase and neutral proteinase did not change; there was a highly significant decrease in the specific activity of the lysosomal hydrolases Cathepsin D and beta glucuronidase. A similar but less dramatic fall was noted in the Darier's patients taking 13-cis-retinoic acid. Darier's patients also had a decrease in neutral proteinase activity before beginning therapy; the specific activity of this enzyme increased during the course of therapy. 13-cis-retinoic acid does not induce clinical remission by increasing the intracellular concentration of lysosomal enzymes in epidermis in vivo.

Evaluation of 13-cis retinoic acid in lamellar ichthyosis, pityriasis rubra pilaris and Darier's disease.

A new synthetic oral retinoid, 13-cis retinoic acid, is fairly well tolerated in patients and appears to be effective in those with Darier's disease and lamellar ichthyosis. It is less effective in those with pityriasis rubra pilaris. The mechanism of action of 13-cis retinoic acid in disorders of keratinization is unknown at the present time; however, it does not appear to cause lysosomal proliferation in therapeutic doses.

Pilomatricomas associated with myotonic dystrophy.

A report of the ninth and tenth cases of myotonic dystrophy associated with pilomatricomas and a review of the previously reported eight cases showed that seven of the ten patients had multiple pilomatricomas. Six of ten patients had another relative with both myotonic dystrophy and pilomatricomas. Patients with both myotonic dystrophy and pilomatricomas are more likely to have multiple tumors and to have a familial occurrence. The prevalence of pilomatricomas in patients with myotonic dystrophy is higher than in the general population. Pilomatricomas may be a cutaneous manifestation of the myotonic syndrome.