Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties. We then focus on reviewing the recent progress on the fabrication of 2D semiconductor optoelectronic devices based on vdW heterostructures including photodetectors, solar cells, and light-emitting devices. Finally, we highlight the perspectives and challenges of optoelectronics based on 2D semiconductor heterostructures.

Abstract-This paper presents an analysis of predicting the load-bearing capacities of human femurs using quantitative computer tomography (QCT)-based beam theory. Crosssectional images of 12 human cadaver femurs (intact bones, age: 39-77 years; male = 8, female = 4) were scanned in conjunction with a calcium hydroxyapatite phantom which has five chambers of known densities. The apparent densities obtained from the scans were used to evaluate the Young's modulus (E) by applying the established empirical relationships. The fracture load of a configuration that simulated single-legged stance was measured experimentally and compared with the predicted failure load using a composite beam theory, plane stress model of the femur. In this model, the failure was assumed to occur at the weakest cross-section through the bone determined from QCT-based structural analysis. In contrast to the other experimental investigations, the setup used in this study considers the entire length of a human femur and also incorporates a novel mechanical jig to mimic the realistic physiological scenario. In one of our earlier studies, simulated lytic defects of varying size were created at the inter-trochanteric region of femurs and their load-bearing capacities were calculated based on their structural properties. Both the results obtained from the current study as well as the ones from our previous study were used to assess the viability of the methodology. A high degree of correlation was observed when the predicted failure loads obtained from the intact femurs and previously studied defective femurs were compared with the ex vivo fracture loads. The coefficients of determination (R 2 ) of QCT-derived predicted loads with respect to the measured failure loads were 0.80 for the intact femurs and 0.87 for the defective femurs. The results suggest that the QCT-derived beam analysis provides a viable approach for the assessment of load-bearing capacity in various clinical scenarios.

Objectives : Approximately 30% of individuals diagnosed with schizophrenia suffer from treatment-resistant schizophrenia. Clozapine is underutilized in the management of treatment-resistant schizophrenia. To understand contributing factors, we analyzed the time course and causes of clozapine discontinuations that occurred over a 20-year period in a clinical setting. Methods : The reasons for discontinuation and duration of clozapine treatment from a retrospective database of 138 patients with schizophrenia who had prescribed clozapine at least a month were reviewed, with the motives for discontinuation coded. The causes for termination were analyzed. Results : Over two-thirds of the patient had ceased clozapine. The two most common causes for discontinuation were side-effects (50%), and own decision (30%). Somnolence accounted for 34% of all side-effects induced discontinuations. Hematological problems accounted for 23% of side-effect. The Maximal treatment dose of clozapine was higher in continuation group (442.36 mg) than in discontinuation group (397.26 mg). The CGI-S score when prescribing clozapine last was higher in discontinuation group than in continuous group. The patients who took atypical antipsychotics before clozapine tended to cease clozapine because of side-effects than who took typical agent. Conclusion : Future studies should seek various methods to relieve side-effects of clozapine. Prospective researches using more objective tools are needed to clarify the reason for clozapine discontinuation. (Korean J Schizophr Res 2016;19:17-24)

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