Two-Dimensional Dirac Fermions Protected by Space-Time Inversion Symmetry in Black Phosphorus

We report the realization of novel symmetry-protected Dirac fermions in a surface-doped two-dimensional (2D) semiconductor, black phosphorus. The widely tunable band gap of black phosphorus by the surface Stark effect is employed to achieve a surprisingly large band inversion up to ~0.6 eV. High-resolution angle-resolved photoemission spectra directly reveal the pair creation of Dirac points and their moving along the axis of the glide-mirror symmetry. Unlike graphene, the Dirac point of black phosphorus is stable, as protected by spacetime inversion symmetry, even in the presence of spin-orbit coupling. Our results establish black phosphorus in the inverted regime as a simple model system of 2D symmetry-protected (topological) Dirac semimetals, offering an unprecedented opportunity for the discovery of 2D Weyl semimetals

Postoperative occlusion of visual axis with fibrous membrane in the presence of anterior capsular phimosis in a patient with pseudoexfoliation syndrome: a case report

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Abstract Background To report a case of postoperative fibrous membrane formation occluding the visual axis in the presence of anterior capsular phimosis in a patient with pseudoexfoliation syndrome. Case presentation A 79-year-old Asian woman with pseudoexfoliation syndrome underwent uneventful phacoemulsification and implantation of one-piece hydrophilic acrylic square-edged intraocular lens (Cristalens) in the right eye. Two months later, she had blurred vision in the right eye with the best-corrected visual acuity (BCVA) of 20/40. Formation of fibrous membrane occluding the capsulorhexis opening with contraction of anterior capsule was observed, which was confirmed by anterior segment optical coherence tomography. Clear visual axis was achieved by lysis of the membrane using Nd:YAG laser. The BCVA improved to 20/20. Conclusions Occlusion of the visual axis with fibrous membrane can develop in the presence of anterior capsular phimosis in a patient with pseudoexfoliation syndrome

Retrospective study on the impact of ulnar nerve dislocation on the pathophysiology of ulnar neuropathy at the elbow

Introduction High resolution ultrasonography (US) has been used for diagnosis and evaluation of entrapment peripheral neuropathy. Ulnar neuropathy at the elbow (UNE) is the second most common focal entrapment neuropathy. The ulnar nerve tends to move to the anteromedial side and sometimes subluxates or dislocates over the medial epicondyle as the elbow is flexed. Dislocation of the ulnar nerve during elbow flexion may contribute to friction injury. We aimed to investigate the effects which the dislocation of ulnar nerve at the elbow could have on the electrophysiologic pathology of UNE. Materials We retrospectively reviewed 71 arms of UNE. The demographic data, electrodiagnosis findings and US findings of ulnar nerve were analyzed. We classified the electrodiagnosis findings of UNE into three pathologic types; demyelinating, sensory axonal loss, and mixed sensorimotor axonal loss. The arms were grouped into non-dislocation, partial dislocation, and complete dislocation groups according to the findings of nerve dislocation in US examination. We compared the electrodiagnosis findings, ulnar nerve cross sectional areas in US and electrodiagnosis pathology types among the groups. Results A total of 18 (25.3%) arms showed partial dislocation, and 15 (21.1%) arms showed complete dislocation of ulnar nerve in US. In the comparison of electrodiagnosis findings, the partial and complete dislocation groups showed significantly slower conduction velocities and lower amplitudes than non-dislocation group in motor conduction study. In the sensory conduction study, the conduction velocity was significantly slower in partial dislocation group and the amplitude was significantly lower in complete dislocation group than non-dislocation group. In the comparison of US findings, patients in partial and complete dislocation groups showed significantly larger cross sectional areas of the ulnar nerve. The comparison of electrodiagnosis pathologic types among the groups revealed that there were significantly larger proportions of the axonal loss (sensory axonal loss or mixed sensorimotor axonal loss) in partial and complete dislocation groups than non-dislocation group. Conclusion The ulnar nerve dislocation could influence on the more severe damage of the ulnar nerve in patients with UNE. It might be important to evaluate the dislocation of the ulnar nerve using US in diagnosing ulnar neuropathy for predicting the prognosis and determining the treatment direction of UNE

Cordycepin inhibits human ovarian cancer by inducing autophagy and apoptosis through Dickkopf-related protein 1/β-catenin signaling

Cordycepin, the major active component from Cordyceps militaris, has been reported to significantly inhibit some types of cancer; however, its effects on ovarian cancer are still not well understood. In this study, we treated human ovarian cancer cells with different doses of cordycepin and found that it dose-dependently reduced ovarian cancer cell viability, based on Cell counting kit-8 reagent. Immunoblotting showed that cordycepin increased Dickkopf-related protein 1 (Dkk1) levels and inhibited β-catenin signaling. Atg7 knockdown in ovarian cancer cells significantly inhibited cordycepin-induced apoptosis, whereas β-catenin overexpression abolished the effects of cordycepin on cell death and proliferation. Furthermore, we found that Dkk1 overexpression by transfection downregulated the expression of c-Myc and cyclin D1. siRNA-mediated Dkk1 silencing downregulated the expression of Atg8, beclin, and LC3 and promoted β-catenin translocation from the cytoplasm into the nucleus. These results suggest that cordycepin inhibits ovarian cancer cell growth, possibly through coordinated autophagy and Dkk1/β-catenin signaling. Taken together, our findings provide new insights into the treatment of ovarian cancer using cordycepin

A Case of Disseminated and Fulminant Plasmacytomas That Developed during Bortezomib Treatment

Multiple myeloma is an incurable and slow growing plasma cell neoplasm. The introduction of new drugs has increased the number of treatment options. Bortezomib, the first-in-class proteasome inhibitor, has been shown to have a significant antitumor activity in the treatment of relapse/refractory patients with multiple myeloma. Additionally, plasmacytomas have shown significant response to bortezomib. In this case report, we describe a patient who developed disseminated and fulminant extramedullary plasmacytomas during combination chemotherapy treatment with bortezomib within a short period, after having shown clinical improvement

Effects of insertion angle and implant thread type on the fracture properties of orthodontic mini-implants during insertion

Objective: To determine the effects of insertion angle (IA) and thread type on the fracture properties of orthodontic mini-implants (OMIs) during insertion. Materials and Methods: A total of 100 OMIs (self-drilling cylindrical; 11 mm in length) were allocated into 10 groups according to thread type (dual or single) and IA (0 degrees, 8 degrees, 13 degrees, 18 degrees, and 23 degrees) (n = 10 per group). The OMIs were placed into artificial materials simulating human tissues: two-layer bone blocks (Sawbones), root (polymethylmethacrylate stick), and periodontal ligament (Imprint-II Garant light-body). Maximum insertion torque (MIT), total insertion energy (TIE), and peak time (PT) were measured and analyzed statistically. Results: There were significant differences in MIT, TIE, and PT among the different IAs and threads (all P<.001). When IA increased, MIT increased in both thread groups. However, TIE and PT did not show significant differences among 0 degrees, 8 degrees, and 13 degrees IAs in the dual-thread group or 8 degrees, 13 degrees, and 18 degrees IAs in the single-thread group. The dual-thread groups showed higher MIT at all IAs, higher TIE at 0 degrees and 23 degrees IAs, and longer PT at a 23 degrees IA than the single-thread groups. In the 0 degrees, 8 degrees, and 13 degrees IA groups, none of the OMIs fractured or became deformed. However, in the 18 degrees IA group, all the OMIs were fractured or deformed. Dual-thread OMIs showed more fracturing than deformation compared to single-thread OMIs (P < .01). In the 23 degrees IA group, all OMIs penetrated the artificial root without fracturing and deformation. Conclusions: When OMIs contact artificial root at a critical contact angle, the deformation or fracture of OMIs can occur at lower MIT values than those of penetration.OAIID:oai:osos.snu.ac.kr:snu2013-01/102/0000004298/8SEQ:8PERF_CD:SNU2013-01EVAL_ITEM_CD:102USER_ID:0000004298ADJUST_YN:YEMP_ID:A072100DEPT_CD:852CITE_RATE:1.184FILENAME:조일식-백승학.pdfDEPT_NM:치의과학과SCOPUS_YN:YCONFIRM: