Phase Transitions and Hysteresis for a Simple Model Liquid Crystal by Replica-Exchange Monte Carlo Simulations

In this work, the advantages of applying the temperature and pressure replica-exchange method to investigate the phase transitions and the hysteresis for liquid-crystal fluids were demonstrated. In applying this method to the commonly used Hess–Su liquid-crystal model, heat capacity peaks and points of phase co-existence were observed. The absence of a smectic phase at higher densities and a narrow range of the nematic phase were reported. The identity of the crystalline phase of this system was found to a hexagonal close-packed solid. Since the nematic-solid phase transition is strongly first order, care must be taken when using this model not to inadvertently simulate meta-stable nematic states at higher densities. In further analysis, the Weighted Histogram Analysis Method was applied to verify the precise locations of the phase transition points

口蓋正中部に発生した粘表皮癌の検討

Mucoepidermoid carcinoma, one type of malignant tumor of the salivary glands, is composed of mucous, squamous, intermediate and clear cells, and mainly occurs in the major salivary glands, especially the parotid gland (60%) and in the minor salivary glands (30%). Clinically, mucoepidermoid carcinoma from originating in the salivary gland of palate is rare. We report a study of mucoepidermoid carcinoma which is composed of clear cells, that occured in the center of palate. A 67-year-old male was referred to our hospital because of mass of his palate. The panorama X-ray and the computed tomography clearly showed a monolocular radiolucent lesion. Biopsy specimen was suspected to be a mucoepidermoid carcinoma. We removed the tumor and partial maxilla under general anesthesia. Histologically, the tumor mainly consisted of clear, mucous, squamous cells, and the histopathologic diagnosis was mucoepidermoid carcinoma. The patient\u27s postoperative course has been good, with no evidence of recurrence as of about one and a half years after the operation