Hydrothermal Synthesis of Cr2Se3 Hexagons for Sensitive and Low-level Detection of 4-Nitrophenol in Water.

We report a simple hydrothermal method used for the synthesis of Cr2Se3 hexagons (h-Cr2Se3) and its application towards electrochemical sensing of 4-nitrophenol (4-NP). The formation of h-Cr2Se3 was confirmed by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical activity of the h-Cr2Se3 modified screen-printed carbon electrode (SPCE) towards 4-NP was studied using cyclic voltammetry (CV) and amperometric i-t techniques. Typically, the obtained results were compared with those for a bare SPCE. The CV result clearly reveals that h-Cr2Se3 modified SPCE has higher catalytic activity towards reduction of 4-NP than bare SPCE. Hence, h-Cr2Se3 modified SPCE was concluded as a viable sensor for sensitive determination of 4-NP. Under optimized conditions, h-Cr2Se3 modified SPCE demonstrates the excellent capacity to detect the 4-NP in a linear range from 0.05 µM to 908.0 µM. The LOD and sensitivity in detection of 4-NP were determined at 0.01 µM and 1.24 µAµM-1 cm-2 respectively. The sensor is highly selective and stable and shows reproducible recovery of 4-NP in domestic supply and river water samples.

Selective Colorimetric Detection of Nitrite in Water using Chitosan Stabilized Gold Nanoparticles Decorated Reduced Graphene oxide.

Excess nitrite (NO2-) concentrations in water supplies is considered detrimental to the environment and human health, and is associated with incidence of stomach cancer. In this work, the authors describe a nitrite detection system based on the synthesis of gold nanoparticles (AuNPs) on reduced graphene oxide (rGO) using an aqueous solution of chitosan and succinic acid. The AuNPs-rGO nanocomposite was confirmed by different physicochemical characterization methods including transmission electron microscopy, elemental analysis, X-ray diffraction, UV-visible (UV-vis) and Fourier transform infrared spectroscopy. The AuNPs-rGO nanocomposite was applicable to the sensitive and selective detection of NO2- with increasing concentrations quantifiable by UV-vis spectroscopy and obvious to the naked eye. The color of the AuNPs-rGO nanocomposite changes from wine red to purple with the addition of different concertation of NO2-. Therefore, nitrite ion concentrations can be quantitatively detected using AuNPs-rGO sensor with UV-vis spectroscopy and estimated with the naked eye. The sensor is able to detect NO2- in a linear response ranging from 1 to 20 µM with a detection limit of 0.1 µM by spectrophotometric method. The as-prepared AuNPs-rGO nanocomposite shows appropriate selectivity towards NO2- in the presence of potentially interfering metal anions.

Central Xanthoma of the Jaw Bones: A Benign Tumor.

Extragnathic xanthomas are seen in the bones or as soft tissue masses. They are often associated with hyperlipidemia and are considered as reactive or metabolic lesions. Only 19 cases of xanthomas of the jaws have been reported so far in the English literature. A total of ten cases of central xanthoma of the jaw bones were identified from the Oral and Maxillofacial Pathology biopsy services of the University of Washington and the Tufts University School of Dental Medicine, between the years 2000-2016. The demographic and clinical information on these cases was tabulated logically on the basis of age, gender, location and presence or absence of symptoms, extragnathic lesions and serum hyperlipidemia. Radiographic and histopathological features were also examined. The findings in these cases were correlated with those available from the previously reported cases. Majority of cases are seen in the second and third decades of life. There is no gender predilection. Jaw lesions presented as solitary radiolucencies with a predilection for the posterior mandible. Unlike maxillary lesions, pain and expansion are inconsistent findings in mandibular lesions. Jaw lesions are not associated with extragnathic bone or soft tissue involvement or a hyperlipidemia. The central xanthoma of the jaws is a unique benign tumor. Histopathologically, many other jaw lesions contain variable numbers of foamy histiocytes. Therefore, a diagnosis of a central xanthoma of the jaws must be made after excluding all other such histiocyte containing lesions. This requires correlation of histopathological findings with clinical and radiographic features.

Ameloblastic carcinoma: an analysis of 14 cases.

OBJECTIVES: To present the classifications of malignant ameloblastomas, provide histopathologic guidelines for the diagnosis of ameloblastic carcinoma, and discuss treatment and long-term follow-up. STUDY DESIGN: Fourteen archival specimens of ameloblastic carcinoma with detailed treatment and follow-up documentation were identified by the authors. RESULTS: Traditional methods of microscopic observation form the basis for diagnosis. Histopathologic features of ameloblastic carcinoma include lack of differentiation, hypercellularity, high mitotic index, vascular invasion, and neural invasion. CONCLUSION: The long-term follow-up findings in this study support the concept that aggressive surgical intervention provides the best chance for survival. Patients treated otherwise had recurrence. The patients with the highest number of recurrences did not survive the disease.