The formation mechanism of ammonium bisulfate (ABS) in the process of SCR flue gas denitrification and some research progresses on ABS are reviewed in the paper. The main factors affecting the formation of ABS are investigated, the formation temperature of ABS is in the range of about 190 degrees C-240 degrees C; ABS exists in vapor phase at temperature between 320 degrees C and 345 degrees C, and begins to decompose when the temperature is higher than 345 degrees C; the formation of the ABS can be reduced by reducing the amount of NH3 slip and SO3, in the flue gas. The adverse effects of ABS on catalyst and air preheater are discussed: ABS will cover the surface of catalyst and Bronsted acid sites, decreasing denitrification efficiency; it will deposit in the air preheater, fouling and corroding the air preheater and reduce its operational effectiveness; it also can reduce the resistivity of fly ash and the quality of the fly ash as well. The methods to control ABS formation and the measures to reduce its negative effects are proposed: Select appropriate operating temperature to reduce the ABS deposition over the SCR catalyst; replace the material of the air preheater components from steel to ceramic coating type and change the structure of the air preheater; Take proper methods to reduce NH3 slip and the oxidation rate of SO2, etc. (C) 2016 American Institute of Chemical Engineers Environ Prog, 35: 1664-1672, 2016
The NMDA receptor is the most widely studied ionotropic glutamate receptor, and it is central to many physiological and pathophysiological processes in the central nervous system. GluN2A is one of the two main types of GluN2 NMDA receptor subunits in the forebrain. The proper activity of GluN2A is important to brain function, as the abnormal regulation of GluN2A may induce some neuropsychiatric disorders. This review will examine the regulation of GluN2A by endogenous and exogenous regulators in the central nervous system.
Emerging multidrug resistance (MDR) to chemotherapy is a major obstacle in successfully treating malignant diseases. Nanotechnology provides an innovative and promising alternative strategy compared to conventional small molecule chemotherapeutics to circumvent MDR. This review focuses on recent literature examples of nanotechnology applications to overcome MDR. The advantages and limitations of various nanotechnologies are discussed as well as possible approaches to overcome the limitations. Developing a practical nanotechnology-based drug delivery system requires further studies of the tumor microenvironment, the mechanisms of MDR to chemotherapy, the optimal dosage regimen of anticancer drugs and/or siRNA, the transport kinetics of nanocarriers in tumor stroma and the pharmacokinetics of drug-loaded nanocarriers within MDR tumor cells. Copyright =C2=A9 2012 Elsevier B.V. All rights reserved.