Crystallization of poly(ethylene oxide) in i-polypropylene–poly(ethylene oxide) blends

A two-stage stable system of isotactic polypropylene–poly(ethylene oxide) blend, in which poly(ethylene oxide) can be permanent either in molten or in crystallized states in the temperature range from 280 to 327 K, was described. The behavior of that blend was explained in terms of fractionated crystallization. A fine dispersion of poly(ethylene oxide) inclusions is required for efficient suppression of crystallization initiated by heterogeneous nuclei. The application of a thin film of polypropylene-poly(ethylene oxide) 9 : 1 blend obtained by quenching for multiuse erasable and rewritable carriers for visible information has been demonstrated. The same sample exhibits different dynamic mechanical properties when poly(ethylene oxide) inclusions are molten or crystallized. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2047–2057, 1997     

Microbial improved oil recovery—bacterial induced wettability and interfacial tension effects on oil production

Microbial Improved Oil Recovery (MIOR) utilizes the effect of oil degrading bacteria that grow on the oil–water interface. It has been demonstrated that the presence of growing bacteria in an oil and water saturated sandstone core can result in significant increased oil recovery upon water flooding [Torsvik, T., Gilje, E. and Sunde, E., Aerobic Microbial Enhanced Oil Recovery, Paper presented at the 5th International Conference on Microbial Enhanced Oil Recovery, Dallas TX, USA, Sep. 11, 1995]. Several mechanisms are proposed to explain this observed effect, among which are reduction in the oil–water interfacial tension (IFT) and changes in the wettability of the system. The experimental results from the present study indicate that bacterial growth can both reduce IFT and change the wettability towards less water-wet conditions. A subsequent simulation study shows that a change in wettability towards a less water-wet behavior can reproduce the increased oil recovery observed during the core flood reported by Torsvik et al. Furthermore, the simulations also indicate that a gradual and strong reduction in IFT can reproduce the same experimental data. Both the effect of changed wettability and reduction in IFT was included in the simulation model as changes to the relative permeability curves, constructed from general theory on IFT reduction and wettability alteration.     

Wettability alterations due to aging in crude oil; wettability and Cryo-ESEM analyses

Several studies of fluid distribution and wettability on the pore scale have been reported, but to our knowledge, none of them have attempted to obtain quantitative measurements. In this paper, quantitative wettability results from Cryo Environmental Scanning Electron Microscopy (Cryo-ESEM) are reported and compared to wettability measurements with traditional methods. The wetting properties of sandstone cores, aged in crude oil, have been investigated using the combined Amott/USBM method. The results show that with increasing aging time, the wetting properties changed from water wet to mixed wetting. Pieces of the same cores have then been analyzed using an Electroscan 2020 ESEM with an attached Cryo unit. Combined with Energy Dispersive X-ray Spectroscopy (EDS), these analyses have given images of the surface, showing the liquid distribution and which phase is contacting the mineral surface.The combination of these methods has proved that using a Cryo-ESEM to investigate wetting properties can give very valuable information although the results are somewhat scattered. Compared to the traditional wetting analyses, this method also gives us an image of the liquid distribution, which is a very valuable input for pore network simulation. It is shown that there is a good agreement between the fraction of the pore walls that are contacted with brine and the Amott/USBM index. A new index based on ESEM data is proposed, with the same range as the Amott–Harvey index.Cryo-ESEM avoids two problems encountered in other SEM methods. First, there is no possibility of a coating layer showing up in the element analyses, since these samples are uncoated. Secondly, the same sample can easily be reexamined by simply refracturing.     

STRUCTURE and PROPERTIES of ALKANAL OXIMES as COPPER EZTRACTANTS

ABSTRACT

Composition, structure and interfacial activity of alkanal oximes and kinetics of copper extraction from chloride solutions are discussed. Semiempirical self-consistent field calculations are used to study the structure of alkanal oximes and their mono- and dihydrates. These calculations are in a qualitative agreement with the ratio of alkanal (Z)-and (E)-isomers, interfacial activity and kinetics data.     

Investigation of electrical properties of nanostructured carbon films derived from block copolymers

Electrical properties of nanostructured carbon (ns-C) films fabricated by pyrolysis of PAN–b–PBA copolymers were investigated. Films having cylindrical morphology and pyrolyzed at 400, 500 and 600 °C were investigated. Both carbide forming (Zr, Ti) and non-carbide forming (Cu, Pt) metals spanning a wide range of electron work functions (4.1–5.5 eV) formed ohmic contacts to the ns-C films in the as-deposited state. The conductivity of the ns-C films increased roughly three orders of magnitude for every 100 °C increase in the pyrolysis temperature. Hall-effect measurements showed that the films pyrolyzed at 600 °C were n-type with a majority carrier concentration and mobility of 5.8 × 10¹⁸ cm^?3 and 0.97 cm²/V s, respectively. Current–voltage measurements as a function of temperature (I–V–T) were performed on films pyrolyzed at 600 °C, whereas films pyrolyzed at 400 and 500 °C were too resistive for reliable resistivity–temperature and Hall-effect measurements. The resistivity as a function of temperature was analyzed by using the reduced activation energy method and was determined to follow variable-range hopping (VRH) mechanisms at and below room temperature. The data indicates a crossover from Efros–Shklovskii VRH [J. Phys. C 8, (1975) L49] to Mott VRH [J. Non-Cryst. Solids 1, (1968) 1] at temperatures above 100 K.     

A novel locus for autosomal dominant nonsyndromic hearing loss, DFNA13, maps to chromosome 6p

Nonsyndromic hearing loss (NSHL) is the most common type of hearing impairment in the elderly. Environmental and hereditary factors play an etiologic role, although the relative contribution of each is unknown. To date, 39 NSHL genes have been localized. Twelve produce autosomal dominant hearing loss, most frequently postlingual in onset and progressive in nature. We have ascertained a large, multigenerational family in which a gene for autosomal dominant NSHL is segregating. Affected individuals experience progressive hearing loss beginning in the 2d-4th decades, eventually making the use of amplification mandatory. A novel locus, DFNA13, was identified on chromosome 6p; the disease gene maps to a 4-cM interval flanked by D6S1663 and D6S1691, with a maximum two-point LOD score of 6.409 at D6S299.     

Optimization of parabolic systems with deviating arguments

Various optimal control problems for linear parabolic systems with deviating arguments given in the integral form are considered. Necessary and sufficient conditions of optimality are derived for the Neumann problem. The optimal control is obtained in feedback form. Making use of theresults of Schwartz, the representation of the optimal feed back control is given. A simple example of application is also provided.     

真空热处理技术的新进展--高压和超高压气淬

１　前言中国热处理行业协会新技术考察团于１９９８年１０月９日参观访问了美国Ｅｒｉｅ城附近的Ｍｅａｄｙｌｌｅ镇ＳＥＣＯ／ＷＡＲＷＩＣＫ公司总部，了解了该公司开发的新技术和新产品。为了有助于我国热处理生产技术的发展，特在此做如下介绍。２　真空高压气淬的效果由于要求真空热处理的零件和材料不断增多，真空加热气冷淬火技术有了迅速发展。工具钢的固溶处理和奥氏体化，合金钢和镍基、钴基合金通常都在熔盐中加热和油中淬火，导致工件开裂和畸变，而且还必须施行后清洗。ＳＥＣＯ／ＷＡＲＷＩＣＫ公司开发的一系列采取对流加热…