The emulsifying properties of a polysaccharide isolated from the fruit of Cordia abyssinica

Polysaccharide was isolated from Cordia abyssinica and its effect, at differing concentrations, on its emulsifying ability was determined. Emulsions of vegetable oil containing up to 1% of the polysaccharide in phosphate pH 7.4 buffer, were prepared by using a hand piston homogenizer. Emulsification was assessed by diluting samples of the emulsions in sodium dodecyl sulphate and measuring absorbance at 500 nm. Addition of increasing concentrations of the polysaccharide up to 1% enhanced emulsification and emulsion stability. Above 1% concentration the polysaccharide solutions were too viscous for making emulsions conveniently. At a constant concentration of the polysaccharide, addition of up to a 1% concentration of salt enhanced emulsion formation. Further addition of salt above 1% resulted in no further changes in emulsifying ability, but the stability of the emulsions formed decreased on increasing the concentration of salt above 1%. The effect of pH on emulsifying ability was investigated by preparing emulsions using buffers of different pH, from pH 3 to pH 13. The polysaccharide had poor emulsifying ability below pH 7. Emulsifying ability increased with pH between pH 7 and 11. At pH above 11 there was a decrease in emulsifying ability.     

多元函数可微性的一个注记

给出了Henle定理的简单证明，并指出该定理在n≥3时不再成立，进而又给出了一个当n≥3时，函数z=f(x1，x2，…，xn)在点M0可微的定理及其证明。     

中原高温高盐油藏疏水缔合聚合物凝胶调剖剂研究

针对中原油田高温(>80℃)、高盐度(>50 g/L)、高硬度(>1 g/L)砂岩油藏,研制了地下成胶的高热稳定性聚合物凝胶调剖剂。所用聚合物为疏水缔合聚合物AP-P4,M=9.0×106,HD=27%,疏水基摩尔分数0.2%;交联剂为可生成酚醛树脂的3种化合物;调剖剂胶液用矿化度160 g/L的马寨油田污水配制;实验温度95℃。根据形成的凝胶黏度(95℃,1.1 s-1)确定交联剂各组分用量为:MZ-YL 0.429%,MZ-BE 0.060%,MZ-XS 0.012%;酸度调整剂用量0.12%;成胶时间10~15小时。2.5、3.0、3.5 g/L AP-P4的凝胶在95℃老化100天后黏度保持在~40 Pa.s及以上。初配制胶液在3000 r/min下剪切15分钟后黏度降低87.5%~89.0%,但成胶后和老化过程中凝胶黏度只比未剪切样降低17.1%~6.6%。3.5 g/L AP-P4的调剖剂对~1μm2的6支储层岩心的堵塞率在88.1%~95.8%范围,平均93.3%,造成的残余阻力系数在15.2~28.6范围,平均19.8,使渗透率级差2.3~8.0的4组双人造岩心的注水流量比发生不同程度的反转。认为该凝胶调剖剂高温下稳定性好的原因,是强化学交联密度低,因而凝胶脱水收缩作用弱。图2表5参5。     

谐振式力传感器对其晶振频率稳定度的要求

为了寻找石英晶振频率稳定度对传感器影响的判据,根据石英谐振式力传感器的灵敏度阈值和量程与晶体的相关常数及结构参数间的关系,导出了反映谐振式力传感器研究水平的指标参数与晶体结构参数及晶振频率稳定度之间的关系式,为传感器的研究提供了依据。例如,欲制作量程阈值比达到105量级的传感器,所用晶振的频率稳定度必须优于108。     

Simulation of the Forming Behaviour of a Boron Modified P91 Ferritic Steel

The forming behaviour at high temperature of a modified 9%Cr‐1%Mo (P91) ferritic steel containing B and Ti for elevated temperature service was investigated. The microstructure of the as‐received material is mainly martensite at room temperature, but special etching revealed prior austenite grains of about 25 μm in size. Torsion tests were conducted at temperatures in the range 850 to 1250 °C to simulate the hot rolling process under comparable conditions of temperature, strain rate and strain. The deformation data obtained from these tests were correlated with the Garofalo equation with a stress exponent of 4.6 and an activation energy of 315 kJ/mol. This equation was used to predict the formability behaviour for the rolling process and also to determine the maximum forming efficiency and stability of the steel. A temperature of 1200 °C is recommended to conduct the forming process.     

Boundary Procedures for Summation-by-Parts Operators

Four different methods of imposing boundary conditions for the linear advection-diffusion equation and a linear hyperbolic system are considered. The methods are analyzed using the energy method and the Laplace transform technique. Numerical calculations are done, considering in particular the case when the initial data and boundary data are inconsistent.     

Mechanical properties and thermal stability of rice husk ash filled epoxy foams

Mechanical properties and thermal stability of epoxy foams filled with white and black rice husk ash were studied. Epoxy foams were prepared from a commercial system and filled with different amounts of both the ashes (0, 6.8, 12.8, 18.0, and 22.7 wt %). The incorporation of both the ashes modified the final morphology of the foam, decreasing the average cell size and increasing the number of cells per volume unit. For all filler percentages used, the specific modulus and strength results showed that the white ash is more effective as reinforcing agent than the black ash. The initial degradation temperature was not affected by the content and type of ash used as the filler. The integral procedure decomposition temperature, weight loss, and char residue results were related to the ash type and atmosphere used in the thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Electrostatic destabilization of water-in-crude oil emulsions: Application to a real case and evaluation of the Aibel VIEC technology

In the current study, the Aibel Vessel Internal Electrostatic Coalescer (VIEC) technology was tested for a real case scenario encountered in the production train of a UK oil field. Depressurized samples were collected both upstream and downstream of the first stage separator. The separation performance was discussed with respect to water cut and droplet size distribution of the emulsions, and the effect of chemical treatment. Issues with respect to representative sampling and testing have been discussed. The application of an external AC electrical field has been shown to significantly enhance the separation of the aqueous phase from tight emulsions, both when it was used alone and in combination with a commercial demulsifier. By using the VIEC technology, the time for separation could be reduced from 8 min to 2 min and the overall BS&W in the emulsions was improved from 45% or 60% to a residual water content of 5-20%. Destabilization of a 45% water-in-oil emulsion by electrical and chemical treatment (20/40 ppm) produced oil in the 2-7% BS&W range whereas the corresponding tests without applying an electrostatic field led to a BS&W greater than 25%. The achieved results strongly suggest that the VIEC technology can resolve the stable emulsion bands encountered in the Schiehallion train and add flexibility or increased production rate to the process. The results also suggest the importance of further studies on the destabilization performances achieved by electrostatic means.     

Influence of the amount of ferromagnetic addition on the rheological properties of spinning solutions,the structure,the strength,and thermal properties of polyacrylonitrile fibres

The rheological properties of spinning solutions of polyacrylonitrile in dimethyl formamide (DMF) containing various amounts of a ferromagnetic nanoaddition were investigated. The porous structure, the strength and thermal properties of fibers obtained from these solutions were assessed, as well as the uniformity of the nanoaddition distribution on the fiber surface was estimated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Development of calibration models for quality control in the production of ethylene/propylene copolymers by FTIR spectroscopy,multivariate statistical tools,and artificial neural networks

Principal component regression (PCR), partial least squares (PLS), StepWise ordinary least squares regression (OLS), and back‐propagation artificial neural network (BP‐ANN) are applied here for the determination of the propylene concentration of a set of 83 production samples of ethylene–propylene copolymers from their infrared spectra. The set of available samples was split into (a) a training set, for models calculation; (b) a test set, for selecting the correct number of latent variables in PCR and PLS and the end point of the training phase of BP‐ANN; (c) a production set, for evaluating the predictive ability of the models. The predictive ability of the models is thus evaluated by genuine predictions. The model obtained by StepWise OLS turned out to be the best one, both in fitting and prediction. The study of the breakdown number of samples to be included in the training set showed that at least 52 experiments are necessary to build a reliable and predictive calibration model. It can be concluded that FTIR spectroscopy and OLS can be properly employed for monitoring the synthesis or the final product of ethylene–propylene copolymers, by predicting the concentration of propylene directly along the process line. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008