The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be class...The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）, the heterogeneous reaction mechanism of NO2 on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO2 on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.展开更多
Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogen...Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography（XCT） and micro-Raman spectrometry to measure individual CaCO_3 particle morphology, with sizes ranging from 3.5–6.5 μm. Particle surface area and volume were calculated using a reconstruction method based on software threedimensional（3-D） rendering. The XCT was first validated with high-resolution fieldemission scanning electron microscopy（FE-SEM） to acquire accurate CaCO_3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual Ca CO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.展开更多
Design and synthesis of a carbamate-linked cationic lipid DDCTMA (N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide)? as gene delivery carriers was described in this work. The transfection efficie...Design and synthesis of a carbamate-linked cationic lipid DDCTMA (N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide)? as gene delivery carriers was described in this work. The transfection efficiency of cationic liposome increased dramatically with the increase in the content of DOPE. In addition, the transfection efficiency of some of cationic lipoplexes was superior or parallel to that of two commercial transfection agents, Lipofectamine2000 and DOTAP. The carbamate-linked cationic lipid DDCTMA/DOPE may be a promising gene carrier that has high transfection efficiency as well as low cytotoxicity.展开更多
基金supported by the National Natural Science Foundation of China (No. 41005071,40490265,20637020)the National Basic Research Program of China(No. 2002CB410802 )the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (No. 09K01ESPCP)
文摘The studies on heterogeneous reactions over montmorillonite, which is a typical 2：1 layered aluminosilicate, will benefit to the Understanding of heterogeneous reactions on clay minerals. Montmorillonite can be classified as sodium montmorillonite or calcium montmorillonite depending on the cation presented between the different layers. Using diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）, the heterogeneous reaction mechanism of NO2 on the surface of montmorillonite was firstly investigated. Results showed that the reaction of NO2 on the surface of sodium and calcium montmorillonite fit a first-order kinetics, and the reaction duration of calcium montmorillonite was longer than that of sodium montmorillonite under the dry condition. For either sodium or calcium montmorillonite, the uptake coefficient decreased as humidity increased.
基金supported by the Chinese Ministry of Science and Technology(No.2008AA062503)the National Natural Science Foundation Committee of China(Nos.41421064,20637020)the China Postdoctoral Science Foundation(No.20100470166)
文摘Heterogeneous reactions on the aerosol particle surface in the atmosphere play important roles in air pollution, climate change, and global biogeochemical cycles. However, the reported uptake coefficients of heterogeneous reactions usually have large variations and may not be relevant to real atmospheric conditions. One of the major reasons for this is the use of bulk samples in laboratory experiments, while particles in the atmosphere are suspended individually. A number of technologies have been developed recently to study heterogeneous reactions on the surfaces of individual particles. Precise measurements on the reactive surface area, volume, and morphology of individual particles are necessary for calculating the uptake coefficient, quantifying reactants and products, and understanding the reaction mechanism better. In this study, for the first time we used synchrotron radiation X-ray computed tomography（XCT） and micro-Raman spectrometry to measure individual CaCO_3 particle morphology, with sizes ranging from 3.5–6.5 μm. Particle surface area and volume were calculated using a reconstruction method based on software threedimensional（3-D） rendering. The XCT was first validated with high-resolution fieldemission scanning electron microscopy（FE-SEM） to acquire accurate CaCO_3 particle surface area and volume estimates. Our results showed an average difference of only 6.1% in surface area and 3.2% in volume measured either by micro-Raman spectrometry or X-ray tomography. X-ray tomography and FE-SEM can provide more morphological details of individual Ca CO3 particles than micro-Raman spectrometry. This study demonstrated that X-ray computed tomography and micro-Raman spectrometry can precisely measure the surface area, volume, and morphology of an individual particle.
文摘Design and synthesis of a carbamate-linked cationic lipid DDCTMA (N-[1-(2,3-didodecylcarbamoyloxy)propyl]-N,N,N-trimethylammonium iodide)? as gene delivery carriers was described in this work. The transfection efficiency of cationic liposome increased dramatically with the increase in the content of DOPE. In addition, the transfection efficiency of some of cationic lipoplexes was superior or parallel to that of two commercial transfection agents, Lipofectamine2000 and DOTAP. The carbamate-linked cationic lipid DDCTMA/DOPE may be a promising gene carrier that has high transfection efficiency as well as low cytotoxicity.
