<乙酸乙酯>合成实验中产品产率计算的讨论

乙酸乙酯合成实验的方法、产品产率计算几种情况的分析讨论。     

Synthesis of Poly (Vinylidene Fluoride)/Modified SBA-15 Nanoparticles Composite Membrane for Water Purification

One of the methods of pollution separating from urban and industrial wastewater is the use of composite membranes based on polymer. The modified composite     

Preparation of electrospun nanofibers based on wheat gluten containing azathioprine for biomedical application

In this study, wheat gluten fibers loaded by the azathioprine were fabricated and their physicochemical properties were studied. The nanofibers were characterized by using the scanning electron microscopy (SEM), Fourier transformed-infrared spectroscopy, X-ray diffractometry, thermogravimetric, and differential thermal analysis. The SEM images showed that the addition of polyvinyl alcohol decreased the fibers’ diameters. The diameters of 77.14?±?14.11?nm were obtained for the wheat gluten–polyvinyl alcohol loaded drug fibers. In addition, the cell viability evaluation conducted by the MTT assay proved no cytotoxicity of the prepared nonofibers at concentrations up to 4?mg/mL to human umbilical vein endothelial cell.     

Sensitivity Investigation of SW-B80N80 Nanotube to Polychlorinated Biphenyl-153 (PCB-153): DFT Methods

Polychlorinated biphenyls (PCBs) is one of the most persistent organic pollutants that exist in the atmosphere and can be concentrated in lithosphere and hydrosphere. Because of low biodegradability and lipophilicity, PCBs accumulate in fatty tissues and through oxidative stress could lead to cancers and central nervous system disorders. Currently, degradation of these synthetic pollutants is one of the environmental issues. The aim of this study is to provide a sensor for detection of PCB-153 (PCB-153). Nano boron nitride compounds (B_nN_m) are magic materials with high stability that can be used as a sensor for detection of chlorinated aromatic compounds. In this study, sensitivity of B₈₀N₈₀ as a form of single-walled boron nitride nanotubes (SW-B₈₀N₈₀ nanotube (8,8)) to PCB-153 has been investigated. The PCB-153 is closed to the SW-B₈₀N₈₀ nanotube and electron exchanges between them have been evaluated using density functional calculations by B3LYP/6–31G^* method. The calculation of the electronic properties has shown that SW-B₈₀N₈₀ nanotube is very sensitive to the presence of PCB-153 molecules. The HOMO/LUMO and gap energy (E_g) changes were considerable. Gap energy decreased from 4.214 eV to 2.022 eV during the formation of complex PCB-153-SW-B₈₀N₈₀ nanotube that leads to conversion of PCB-153 into the other products. According to thermodynamic parameter calculation through the IR-DFT method, it is expected that SW-B₈₀N₈₀ nanotube will be a suitable candidate in the elimination of PCB-153, as well as a gas sensor.     

Mixing of Oil in Water Through Electrical Resistance Tomography and Response Surface Methodology

The mixing performance of the oil‐in‐water dispersion system was evaluated. Using an electrical resistance tomography system composed of two measuring planes, the effect of parameters such as impeller type, impeller speed, oil type, and oil volume fraction on the mixing performance through axial mixing indices were explored. The oil type and the oil volume fraction were identified as the most influential factors on the mixing index. Castor oil, with the highest viscosity of the tested oils, was found as the most difficult oil to disperse. The Scaba impeller was the most efficient impeller in dispersing oil in water. The interactions between oil type and impeller type as well as between impeller speed and oil type, had the greatest impact on the mixing index.     

Complete forward displacement solutions for a class of three-branch parallel manipulators

Forward displacement solutions are presented for a class of spatial parallel manipulators. In particular, considered are manipulators consisting of a platform supported through passive spherical joints by three branches, each branch having three-revolute joints forming its main arm. Solutions are described for arbitrary main-arm layouts and for all possible cases of redundant (nine, eight, and seven sensors) and non-redundant (six sensors) sensing of branch main-arm joint displacements. It is demonstrated that closed-form forward displacement solutions can be found for all cases of redundant sensing. Furthermore, it is shown that a closed-form solution can be obtained for one of the two possible cases of non-redundant sensing of the main-arm joint displacements. The only case of joint displacement sensing not allowing a closed-form forward displacement solution is two joints sensed per branch, a case that can be expressed as a 16th-order polynomial of a single variable. Due to the importance of having efficient and failure-safe solutions for the forward displacement problem, it is suggested that appropriate redundancy in displacement sensing should be an important consideration in the design of parallel manipulation devices. © 1994 John Wiley & Sons, Inc.