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Using a Green function method based on an atomic vibration model, herein we report the results from our investigation of phonon transport through multiple Si/PtSi layered structures. In contrast with values predicted using elastic wave theory and an impedance mismatch method, we find that a detailed atomic-vibration approach exhibits significantly suppressed phonon transport and leads to a 30-times reduction of the thermal conductance, compared to that of Si bulk. We attribute the origin of the suppression to the lack of PtSi phonon modes in the energy range of 20-30 meV, and to the effects of interface scattering between Si and PtSi layers. [ABSTRACT FROM AUTHOR]

Ferroelectric (Ba,Sr)TiO3 films have been deposited on (001) MgO single crystals by a pulsed laser deposition with oxygen background while heating the substrates. Deposited BST films exhibit epitaxial growth along (001), which are confirmed by x-ray diffraction measurement. Structure of (Ba,Sr)TiO3 along in-plane and surface normal direction have been investigated and found to have a tetragonal distortion depend on the deposition conditions, such as oxygen pressure. Lattice parameter decreases with increasing oxygen pressure, and tetragonallity (c/a) changes from 1.005 to 0.997 as oxygen pressure increase. Interestingly, energy gap measured by FTIR decreases with decreasing oxygen pressure until it reach a certain oxygen pressure, then increases again with increasing oxygen pressure. Furthermore, microwave properties of devices measured by a HP 8510C vector network analyzer from 0.045-20 GHz suggest that the least distorted films exhibit a larger dielectric constant changes with dc bias field. [ABSTRACT FROM AUTHOR]

An electrical resistivity evaluation method for a pillar-shaped solid material, especially a brittle thermoelectric Bi2Te3, is presented with short compensation based on a probing apparatus with four-spring pins. The method eliminates the process of modelling a complex contact resistance, resulting in a simple but reproducible characterisation without any contamination on the surface in comparison to either a conventional paste or welding contact. Furthermore, it enables a small electrical or thermoelectric material <2 mm thick to be appropriately evaluated, which can erect and align a pillar-shaped material with electrical terminals, in spite of a small surface area. To extract the resistivity of a Bi2Te3 pillar with the volume of 2 x 2 x 1.6 mm, Alumina 6061-T6 material identical with that of Bi2Te3 was used as a reference material for the short compensation. Thus, the modelled resistance and its resistivity were 2.46 ± 0.11 mΩ and 6.15 ± 0.28 Ω-µm, respectively, in the range of 2-10 kHz, demonstrating the validity of the method. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine oral health attitudes/behavior and gingival self-care levels of Korean dental hygiene students (n = 271). A questionnaire known as HU-DBI (Korean version) was administered to each class. Higher scores of the HU-DBI indicate better oral health attitudes/behavior. The student's gingival self-care level was scored as excellent (+2), good (+1), questionable (0), poor (-1), or very poor (-2) according to the criteria of the Oral Rating Index (ORI) for youth. The mean score of the HU-DBI was 6.40, and that of the ORI was +0.12. Most samples scored 0 or +1. The mean HU-DBI scores of year-2 and year-3 students (7.06, and 7.61 respectively) were significantly greater than that of year-1 students (5.23) (P<0.001). Twenty-three percent of the students reported a belief that they may eventually require false teeth. Half stated that they put off going to the dentist until they had toothache. Year-1 students were more likely to have this attitude compared to year-3 students. HU-DBI scores were significantly associated with ORI scores (r = 0.315; P<0.001). The differences in the HU-DBI and ORI scores across the level of education were highly significant.

Background: Many clinicians perform glycolic acid peels for facial acne patients, but there has not been a well-controlled study to compare this new therapy with other conventional modalities., Objective: To compare the effectiveness of treatment and side effects in the treatment of facial acne by two agents, 70% glycolic acid and Jessner's solution., Methods: Twenty-six patients with facial acne were treated simultaneously with 70% glycolic acid and Jessner's solution biweekly on each side of the face. The treatment sides were randomized and the evaluation of treatment was done biweekly by a blinded evaluator who did not know the randomization code. Dr. Cunliffe's acne grading system was used for objective comparison. All patients were also asked about the improvement of facial acne and about the side effects experienced. Finally, the patients answered the preference test between the 2 peeling methods., Results: Acne grading of both treatments improved after 3 treatment sessions. However, there were no significant differences in treatment effects between the 2 methods. As far as side effects were concerned, sites treated with Jessner's solution showed a significantly increased degree of exfoliation compared to glycolic acid (p < 0.01)., Conclusion: Glycolic acid is less widely used than Jessner's solution due to its inconvenient application technique. But considering the equal treatment effect and lesser degree of exfoliation in glycolic acid, we would recommend the use of glycolic acid over Jessner's solution for acne patients.

Background: Several clinical reports have suggested that alpha hydroxy acids (AHAs), including glycolic acid, may improve photoaging. However, the mechanism of action of glycolic acid is not well understood., Objective: In order to investigate the mechanism of action of glycolic acid in improving photoaged skin, we observed the effect of glycolic acid on collagen metabolism and wrinkle effacement in chronically ultraviolet B (UVB) irradiated mice., Methods: Skh:HR-1 mice were exposed to UVB for 10 weeks and then treated topically with 15% glycolic acid for 10 weeks. We assessed the improvement in wrinkling, the depth of the dermal repair zone, and the extent of the increase in collagen synthesis., Results: At treatment week 10, the glycolic acid-treated mice showed a significant decrease in wrinkle score, an increased thickness of the dermal repair zone, and an increase in the amount of collagen synthesized compared to vehicle (hydrophilic ointment base) treated mice., Conclusion: Topically applied glycolic acid may improve photoaging through modulation of collagen production.

Subungual osteochondroma is a rare form of benign bone tumor characterized by distinctive histopathological and radiological findings. The major clinical manifestation is a firm mass with tenderness. It must be differentiated from other similar diseases such as subungual exostosis, glomus tumor, and enchondroma to determine the proper surgical procedure. A 13-year-old boy had a history of a growing tender mass on the right third toe which recurred after simple excision. He was treated by careful dissection and total excision under local anesthesia. Histologic findings included a trabecular bone formation covered with hyaline cartilage cap and were compatible with osteochondroma.

We report a 25-year-old man who had two protruding firm masses on his suprasternal region. These lesions were present at birth without any family history. He had no other subjective symptoms. In a histological specimen, there were numerous unevenly distributed telogen follicles that contained vellus hairs. Beneath a relatively narrow zone of fibrovascular tissue, lobules of fat with a central core of cartilage were seen. The mass was totally excised; during the follow-up period, there was no evidence of recurrence. The tragus derives from the first branchial arch. The accessory tragus can be found along the entire course of embryonic migration. It is usually located unilaterally in the preauricular region. To our knowledge, bilateral development on the suprasternal region has not been previously reported.

A 55-year-old male suffering from liver cirrhosis presented with diffuse annular hyperkeratotic papules of abrupt onset on the trunk and extremities. Histopathologic examination revealed cornoid lamella and eosinophilic spongiosis. He did not receive any medications other than cephalosporin for spontaneous bacterial peritonitis. A review of the literature revealed that three cases developed porokeratosis when their liver function declined and that, in one case, the porokeratosis disappeared spontaneously with liver transplantation. Although the precise mechanism is unclear, there is evidence demonstrating immunoincompetence in cirrhosis. Even though we did not perform immunologic studies or exclude the possibility of drug-induced porokeratosis in our case, it is conceivable that porokeratosis can be triggered by immunosuppression due to liver cirrhosis per se.