Keywords: P-Chiral phosphane oxides / Alkylations / Halides / MetallationsP-Chiral tertiary phosphane oxides have been prepared from each of the secondary phosphane oxides racemic 1, (S P )-(−)-4 and (R P )-(+)-tert-butylphenylphosphane oxide (5) by lithiation with LDA or nBuLi, or sodiation with sodium hydride, in THF, and then by treatment with a series of primary alkyl halides. Doubly P-chiral ditertiary bis(phosphane oxides) are also obtained from these metallated secondary phosphane oxides by treatment with electrophiles based on straight-chain, tartrate-derived, and bishalomethylarene dihalides. In general, the bis-phosphane oxides are obtained in good yields. However, when the α,ω-dihalide bears an em-
Pretreatment is one of the most important unit operations for ethanol production from biomass feedstocks. In this study, corn stover was used as a feedstock to examine the effectiveness of two pretreatments: electrolyzed water pretreatment and a two-step pretreatment. Electrolyzed water was employed as a catalyst to conduct one-step pretreatment of corn stover at three temperatures (165, 180 and 195°C) and three treatment times (10, 20 and 30 min). During the two-step pretreatment process, an organic alkaline solution of 1% (w/w) NaOH in 70% (w/w) ethanol was used for lignin removal in the first step, followed by a second step using hot water. No furfural or 5-hydroxymethyl furfural was detected in the hydrolysates from both pretreatment methods when the detection limit of the HPLC was 0.2 g/L. The highest glucan conversion yields were 83% obtained at 195°C for 30 min with acidic electrolyzed water and 83% by the two-step process, where the second step of the pretreatment was at 135°C for 30 min. The hydrolyzates from the two pretreatment methods showed good performance in Saccharomyces cerevisiae fermentation tests. The two new methods may provide promising alternatives for the pretreatment of biomass for ethanol production. ethanol, biomass, pretreatment, inhibitor Citation:Wang X J, Feng H, Li Z Y. Ethanol production from corn stover pretreated by electrolyzed water and a two-step pretreatment method.
The research about the high pressure technology to preserve foodstuff has been studied for a longer time, but there were few of papers about the research of the combination effects of high-pressure-freezing&thawing process on food qualities. To examine the combination effects of high-pressure-freezing&thawing process on food qualities, potato was chosen as model object. The experiments were conducted with pressure-shift-freezing processes at 0.1, 100~200MPa, and pressure-assisted-thawing processes at 0.1, 200MPa. Texture analysis was as the key index to evaluate the combination effects of high-pressure-freezing&thawing process on food qualities by Texture Analyzer. At the same time the frozen samples treated by pressure-shift-freezing process were histologically analyzed using the isothermal freezing substitution technique to contrast the pressure effects on the size and shape of ice crystal. The sizes and locations of ice crystals in samples as a result of pressure-shift-freezing were compared to those obtained by atmospheric freezing. The results showed that the combination of pressure-shift-freezing and pressure-assisted-thawing process made less change on the cell wall.
Using a two-dimensional Discrete Element Method (DEM) computer simulation, dense granular flows with the particle size range of 2-3 mm were studied between two vertical waved plates. The hydrodynamic characteristics, such as flow pattern, distribution of stress, velocity and trajectory of particles were analyzed in the process of granular flow. The results were compared to those of the flows between two vertical flat plates. The results indicated that the transient stress between waved plates was heterogeneous; the zigzag-like pressure profiles on the waved pate increased. Conclusions could be drawn that the formation of dense particle clusters disturbed spatial homogeneity and resulted in collisional anisotropy which was propitious to enhance the process of momentum, heat and mass transmission.
The two-way mass transfer behavior between solvent and non-solvent is a key factor effecting on the pore size and size distribution of 3-D scaffolds formed by ScCO2induced phase separation process. The mathematical model of the mass transfer related to this process is presented on the basis of the model developed by Reuvers. By means of the composition paths calculated by this model in the ternary phase diagram, the pore size and size distribution of PLLA 3-D scaffolds are analyzed under different conditions (solution concentrations, CO2pressures and temperatures).The calculated results are verified by experiment. The results show that the pore size of the PLLA 3-D scaffolds increases with the decrease of solution concentration and increase of the CO2pressure and temperature.
The supercritical fluid impinging technology combined with fluidized bed (SFIT-FB) process is a novel technique to prepare microcapsules. The process was performed using ultra-fine glass beads as the core particle and paraffin the coating material. The influences of operation parameters, including the pressure and the temperature of mixing vessel and the impinging distance on the microcapsule morphology, size distribution and coating rate were investigated. The microcapsule characteristics could be controlled by adjusting the operation conditions. A number of techniques were used for the characterisation of the microcapsules. A scanning electron microscope (SEM) was used to examine the morphology of particle surface. A laser particle size analyzer (LPSA) was used to measure the particle size distribution, and differential scanning calorimeter (DSC) measurements were conducted to determine the apparent coating rates of microcapsules. The advantages of SFIT lies in enhancing the mass transfer and heat transfer, which prevent particles agglomeration.
ZrO2 nano-particles were successfully prepared by supercritical hydrolysis in two steps (hydrolysis and dehydration) and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle-size analyzer. The influences of operation parameters, including operation pressure and temperature, CO2 total flow and ratio of CO2 branch flow, on the particles were investigated experimentally. The results show that average particle size increases with the increase of the operation temperature, while it decreases with the increase of the operation pressure and the CO2 total flow. The smallest particles with average diameter of 793nm can be prepared under the condition: operation temperature and pressure of 50°C and 8MPa, CO2 total flow of 30 standard cubic centimeter per Minute and ratio of CO2 branch flow of 3.
Simulation method was applied to study the fouling behavior during the Micro-filtration of Semi-conductor wastewater. In the numerical model, concentration dependent physical properties such as suspension viscosity, density and generalized particle transport diffusivity were considered. The mechanism of suspension transition from liquid phase to gel phase was adopted to characterize the formation of membrane fouling. Fouling resistance distribution along the membrane surface was obtained from the simulation. The results revealed the mass transfer character in the concentration boundary layer and its influence on the formation of membrane fouling. Agreement between the simulation and the experiment results demonstrated the applicability of this numerical method in evaluating membrane fouling during Micro-filtration.
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