Experimental Simulation of the Reactor Section of Fluid Cokers: Comparison of FCC and Fluid Coke Particles

The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ～20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core‐annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers.     

Preparation of Monodisperse ZrO2 by the Microwave Heating of Zirconyl Chloride Solutions

Based on the principle that the solubility of a salt decreases as the dielectric constant of the solvent decreases, zirconia powders were prepared by heating a zirconyl chloride solution with a 2-PrOH-water mixture as the solvent. The morphology, size, and size distribution of the resulting particles were highly sensitive to the heating method used on the starting solution. Particles formed under conventional heating methods were polydisperse, agglomerated spherical, or irregularly shaped because of inhomogeneous precipitation through the temperature gradient, the shear force induced by stirring, compositional nonuniformity, and the low heating rate. The present study demonstrated that microwaves provide an excellent means of heating uniformly and rapidly without stirring. The particles resulting from microwave treatment were monodisperse and spherical, with a mean diameter of 0.28 μm.     

气—液鼓泡塔中流动域和气含率的分布

利用压力传感器测定了气、液两相鼓泡塔内不同轴、径向位置上压强的脉动信号,分析了压强的脉动特征,计算了各种操作条件下塔内不同轴向位置截面上的平均气含率,发现在不同操作条件下,塔内可能出现不同的流动域分布,即全塔均匀鼓泡域、全塔过渡域、全塔湍动鼓泡域以及均匀鼓泡域,过渡域和湍动鼓泡域中的相邻2种或3种流域同时出现在塔内不同高度上。提出了不同轴向位置流域转变的判据。并发现,同一截面的不同径向位置基本处于同一流域内。同时研究了鼓泡塔内气含率在轴向上的分布规律,给出了不同流动域内气含率的关系式。     

Preparation of pH‐sensitive poly(vinyl alcohol‐g‐methacrylic acid) and poly(vinyl alcohol‐g‐acrylic acid) hydrogels by gamma ray irradiation and their insulin release behavior

A series of pH‐responsive hydrogels were studied as potential drug carriers for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared by a two‐step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto these poly(vinyl alcohol) hydrogels with subsequent irradiation (5–20 kGy). These graft hydrogels showed pH‐sensitive swelling behavior and were used as carriers for the controlled release of insulin. The in vitro release of insulin was observed for the insulin‐loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 636–643, 2004     

土体固结粉在软土地基加固中的应用研究

针对上海地区软土地基特点,利用工业废渣为主要原料配制成新型土体固结材料——土体固结粉。通过室内的无侧限抗压强度及XRD试验得出其固化土的强度性能及加固机理;再通过室外原位搅拌桩施工及芯样试验进行分析,研究了土体固结粉在软土地基加固实际工程中的适用性。     

Non-Isothermal crystallization of isotactic polypropylene in dotriacontane. II: Effects of dilution,cooling rate,and nucleating agent addition on growth rate

Non-isothermal crystallization growth rates of nucleated and non-nucleated isotactic polypropylene (iPP) in dotriacontane were determined experimentally by thermal optical microscopy. Adipic acid was used as the nucleating agent. The non-isothermal growth rates of the nucleated and non-nucleated systems were compared with experimentally determined isothermal growth rates. The Lauritzen and Hoffman growth rate equation, originally developed for isothermal crystallization, was modified to describe the non-isothermal growth. The modified Lauritzen-Hoffman equation was used to predict isothermal growth rates from non-isothermal crystallization for the nucleated and non-nucleated polymer-diluent mixtures. This study is the first to deal with polymer-diluent-nucleating agent systems vital to membrane production.     

1-苯基-3-甲基-5-吡唑啉酮的合成工艺研究

在无水乙醇的存在下，乙酰乙酸乙酯和苯肼为原料合成标题化合物、采用单因素实验法，得到最佳配比为乙酰乙酸乙酯：苯肼=1.05(摩尔比)，无水乙醇50m，反应温度70℃，反应2小时，再回流7小时，收率90．9％，产品纯度99.0％以上。     

Estimation bias of ocean current measured by along-track interferometric synthetic aperture radar and its compensation methods

In previous works on current measured by along-track interferometric synthetic aperture radar (ATISAR), the decorrelation function of an ocean-surface backscattering signal was usually assumed to be a real Gaussian function, i.e. the phase term was omitted. In this study, it is proved that the omission of the phase term included in the decorrelation function results in a significant estimation bias that can be modelled by a higher-order function of time lag and that the coefficients of this higher-order function can be expressed as a series of higher-order Doppler spectral moments. This model is validated by the scatterometer data obtained from an experimental wind-wave tank. The estimation bias especially needs to be considered for the ATISAR system with a long time lag. Simulation results show that if the time lag is equal to the coherence time, the estimation bias of the current can reach about 0.2 m s^?1, which is not insignificant in high-precision current-retrieving applications. However, because most real-life ATISAR systems, including TerraSAR-X, operate with time lags significantly shorter than the expected coherence time, the estimation biases in these systems are relatively small or even negligible. Finally, four possible compensation methods for the estimation bias are proposed and discussed.     

Recent climate variability and its impact on precipitation,temperature, and vegetation dynamics in the Lancang River headwater area of China

The alpine ecosystem is one of the most fragile ecosystems threatened by global climate change. The impact of climate variability on the vegetation dynamics of alpine ecosystems has become important in global change studies. In this study, spatially explicit gridded data, including the Moderate Resolution Imaging Spectroradiometer (MODIS) land-surface temperature (LST) product (MOD11A1/A2), the Tropical Rainfall Measuring Mission (TRMM) rainfall product (3B43), and MODIS net primary productivity (NPP) product (MOD17A3), together with meteorological observation data, were used to explore the spatio-temporal pattern of climate variability and its impact on vegetation dynamics from 2000 to 2012 in the Lancang River headwater area. We found that the variation patterns of LST, precipitation, and NPP in the study area showed remarkable spatial differences. From the northwest to the southeast the spatial variation of average annual LST exhibited a decreasing–increasing–decreasing–increasing pattern. At the same time, most of the study area exhibited an increasing LST during the growing season. The annual precipitation increased in the semi-arid northern part, whereas it decreased in the semi-humid southern part. The precipitation variability during the growing season has a pattern similar to the annual precipitation variability. Although the majority of the regions have seen an NPP increase from 2000 to 2012, the responses of the vegetation to the varied climate factors were spatially heterogeneous. The alpine–subalpine meadows in the high-altitude areas were more sensitive to climate variability in the growing season. It is argued that satellite remote-sensing products have great potential in investigating the impact of climate variability on vegetation dynamics at the finer scale, especially for the Lancang River headwater area with complex surface heterogeneity.     

Wetting properties of polystyrene ionomers treated with plasma source ion implantation

The wetting properties of polystyrene‐based ionomers treated with plasma source ion implantation (PSII) were investigated by the measurement of water contact angles. When sulfonated ionomers were aged for a few days, the hydrophobic recovery for the ionomers became much slower than that for the nonionic polymers. However, when the samples were aged over 20 days, the water contact angle of the ionomers converged with that of the nonionic polymer. Thus, it was concluded that the ionic interaction between the ionic groups and the presence of ionic groups together resulted in the slow hydrophobic recovery and that the aging effect was significant for the ionomers. For the methacrylate ionomer of low ion content, on the other hand, it was found that the PSII treatment produced only a small change in hydrophobic recovery behavior. Thus, it was suggested that the low ionic content coupled with the small size of the ionic unit might cause changes only of a very insignificant degree in hydrophobic recovery behavior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2500–2504, 2002