Facile Synthesis of Carbon Dots@2D MoS2 Heterostructure with Enhanced Photocatalytic Properties.

To better utilize carbon dots (CDs) as efficient photocatalysts, an excellent strategy of constructing CDs@MoS2 heterostructure is presented. Here a facile sonication-hydrothermal method is utilized to synthesize CDs@MoS2. Such heterostructure regulates the energy level configuration, and visible light absorption and the separation and transfer of photogenerated charges are enhanced remarkably, which is propitious for the production of more photoinduced charges and improvement of the heterogeneous photocatalytic activity. Meanwhile, the photocatalytic performance of CDs@MoS2 was obviously improved in methylene blue degradation. On the basis of a series of contrast experiments, the possible mechanism of the photocatalytic reaction is proposed. Therefore, this work offers a facile route for the design of a zero-dimensional/two-dimensional heterojunction for the adjustment of the energy level structure and the improvement in photocatalytic performance.

A simple, scalable approach for combining carbon dots with hexagonal nanoplates of nickel-based compounds for efficient photocatalytic reduction.

Hybrid nanostructures comprising disparate materials and having intricate shapes and facets are highly desired in photocatalytic applications requiring high selectivity. However, to produce such structures requires precise morphological control, and this is largely dictated by the stringent requirements of the reaction conditions, in addition to intricate, expensive, or tedious preparation steps. We present a simple, inexpensive, and scalable method for the preparation of hybrid nanostructures that combines carbon dots with hexagonal nanoplates of nickel-based compounds. The resultant heterostructure not only improves visible light absorption, but also exhibits enhanced photocatalytic activity for the reduction of 4-nitrophenol to 4-aminophenol when compared to carbon dots or hexagonal nanoplates of nickel-based compounds alone. The enhanced photocatalytic activity is due to the higher separation and transfer efficiency of photoexcited charge carriers at the interface between the carbon dot and hexagonal nanoplate of nickel-based compounds. This work opens up a straightforward and effective route to yield inexpensive and efficient photocatalysts for improved solar energy capture and conversion.

[Value of manifestations of magnetic resonance imaging (MRI) in diagnosis of parotid tumors and their pathological bases].

BACKGROUND & OBJECTIVE: The pathologic types of parotid tumor are very complicated and the advantage of magnetic resonance imaging (MRI) in diagnosis of these tumors is very obvious; however, there is not still accordance at several areas of MRI diagnosis of them. A large amount of cases are needed for analyzing these MRI features and their pathological fundament. This study was conducted to summarize the MRI manifestations of common benign and malignant tumors and to explore the value of the morphological features of MRI in histological diagnosis of parotid tumor. METHODS: The MRI manifestations for 132 cases(140 lesions) of parotid tumor/lesion were collected, including 89 benign tumors/lesions and 43 malignant tumors. Of them, 112 cases were proved by surgery, 17 cases by biopsy, and 3 cases by clinic observation. MRI features were completely compared with pathological results of surgical samples slice by slice in 58 cases. T(1)WI and T(2)WI sequence were used in MRI unenhancement scan; 108 cases (115 lesions) were examined with both unenhancement and enhancement. Chi-square test was used for statistic analysis. RESULTS: (1) The MRI features of common parotid benign tumors were as following: 40 cases of Warthin's tumors enhanced slightly and more than half of them (25 cases) appeared low or equal signal intensity in T(2)WI; 22 cases of pleomorphic adenoma appeared high and unhomogeneous signal intensity in T(2)WI; 5 cases of hemangioma were characterized by their vascular structures which were enlarged than normal; 3 cases of lymphangioma not only appeared specially irregular shape but also surrounded adjacent structures of parotid gland (3 cases). The features of 4 cases of parotid lipoma were same as those in other position of the body.(2) The MRI features of common parotid malignant tumors were as following: 8 cases of malignant pleomorphic adenoma appeared high and unhomogeneous signals in T(2)WI together with irregular shape and ill-defined margin; 7 cases of adenoid cystic carcinoma characterized by invasion of very large range surrounding parotid gland. In 8 cases of malignant mucoepidermoid carcinoma, 3 cases showed low-grade malignant mucoepidermoid carcinomas, which had well-defined margin and were difficult to distinguish from benign tumor. However, 5 cases of high-grade malignant mucoepidermoid carcinoma showed ill-defined margin, their features were tend to undergo necrosis and invade lymph node; 9 cases of lymphomas were all secondary lesions and there were two characters in their imaging, one was the wide involved range, the other was they consisted of several nodes. The shapes of 3 cases acinic cell carcinoma could be either regular or irregular, the cystic areas could be found in them with high signal intensity both on T(1)WI and T(2)WI. CONCLUSION: There are certain characters for each of common benign and malignant parotid tumors in MRI and these may be helpful for histological diagnosis in most of them.