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1.
《Discrete Mathematics》2019,342(6):1564-1576
2.
《Arabian Journal of Chemistry》2022,15(9):104035
In this study, we used the Span 80 to enhance solvent extraction process, and we explored the mechanism. The results indicated different solvents would obtain different oil recovery, and toluene showed the optimal oil recovery, and the n-heptane showed the lowest oil recovery. The complex solvents could improve oil recovery. Toluene could make the heavy oil show the lowest viscosity (89.6 Pa.S), and n-heptane make the heavy oil show the highest viscosity (176.3 Pa.S). Complex solvents could decrease the heavy oil viscosities. The higher C/H was, the higher heavy oil recovery was, and when the asphaltene and resins content increase, the C/H would increase. The C/H showed the highest value (9.09, by toluene) and the lowest value (8.15). In this study, Span 80 could increase heavy oil C/H ratio, decrease heavy oil viscosity. Span 80 could make the sands surface more hydrophilic, and then the solvent loss would decrease. The oil recovery was high after 10 times recycle use. 相似文献
3.
The aims of this study are to form a liquid membrane suitable for the extraction of strontium ions from aqueous solutions and to determine the factors influencing the stability of the membrane, the extraction efficiency and the rate of transport. The suggested membrane is composed of kerosene, Span 80 and D2EHPA. It has been observed that the extraction efficiency and the rate of transport increase with increasing ratio of emulsion to outer phase volume, stirring rate and D2EHPA concentration and decreasing pH of the inner phase. As the strontium ion concentration in the outer phase increases, the transport rate increases but the separation efficiency decreases. The maximum separation efficiency achieved in the experiments was 92%. 相似文献
4.
A defined change in formulation components affects the physical and chemical characteristics of cationic liposomes (CLs) carriers in many ways. Therefore, a great degree of control can be exercised over the structure by modifying the CLs with various materials, leading to new innovations for carrier improvement. In the present study, surface modifications of cationic liposomes with non-ionic surfactants—sorbitan monoesters serials (Span 85, 80, 40 and 20) were carried out for developing a new gene transfer carrier. Span modified cationic liposomes (Sp-CLs) were prepared by reverse phase evaporation method (RPV) and self-assemble complexes of antisense oligonucleotides/surfactant modifying cationic liposomes were prepared by auto-coacervation through electrostatic effect. Characterization of Sp-CLs and the self-assembled complex was performed by electron microscope, particle size, zeta potential, turbidity and agarose electrophoresis. Furthermore, in vitro cellular uptake experiment showed that Span plays a role in enhancing the cellular uptake of encapsulated oligonucleotides mediated by Sp-CLs by the endocytosis-dependent route. CLs modified with Span 40 significantly facilitated the cellular uptake by COS-7 cells and HeLa cells; also showed some positive effect on gene expression. That suggests it is a potential non-viral carrier for efficient gene transfer. 相似文献
5.
In this report we analyze differences in reasoning about span and linear independence by comparing written work of 126 linear algebra students whose instructors received support to implement a particular inquiry-oriented (IO) instructional approach compared to 129 students whose instructors did not receive that support. Our analysis of students’ responses to open-ended questions indicated that IO students’ concept images of span and linear independence were more aligned with the formal concept definition than the concept images of Non-IO students. Additionally, IO students exhibited more coordinated conceptual understandings and used deductive reasoning at higher rates than Non-IO students. We provide illustrative examples of systematic differences in how students from the two groups reasoned about span and linear independence. 相似文献
6.
A reactive type dripping anti-condensation agent, Span 60-IAH, was grafted onto linear low density polyethylene (LLDPE) by β-ray pre-irradiation and reactive extrusion. Effects of total dose, monomer concentration and extrusion temperature and rate on the degree of grafting were studied in detail. It was shown that the optimum conditions for grafting were the extrusion temperature of 130–220°C, screw run speed of 90 rpm and total β-ray dose of 12.5 kGy. The structure of the LLDPE-g-(Span 60-IAH) (LS) was characterized by Fourier-transform infrared spectroscopy (FT-IR). The tensile properties and light transmission properties of extruded films were determined. The thermal behavior of the LS was investigated by using differential scanning calorimetry (DSC). Compared with pure LLDPE, the crystallization temperature (Tc) of LS increased about 3°C. Accelerated dripping properties of film samples were investigated. The dripping duration of the LS film and a commercial anti-fog dripping film at 60°C were 45 days and 17 days, respectively, indicating a significant improvement. 相似文献
7.
Antonio Cossidente 《Designs, Codes and Cryptography》2009,51(2):123-129
In the geometric setting of commuting orthogonal and unitary polarities we construct an infinite family of complete (q + 1)2–spans of the Hermitian surface , q odd. A construction of an infinite family of minimal blocking sets of , q odd, admitting PSL
2(q), is also provided.
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8.
The aggregation equilibria of the commercial extractant Cyanex 302 in toluene have been studied by vapor pressure osmometry (VPO) at different temperatures. The experimental data, treated both graphically and numerically by means of the CPMIN program, can be explained by assuming the formation of a dimer species of the active component bis(2,4,4-trimethylpentyl)thiophosphinic acid for which the aggregation constants have been determined at 28, 40 and 50°C. The influence of other components of the commercial reagent in the aggregation equilibria have also been considered. The interaction between Cyanex 302 and the non-ionic surfactant Span 80 in toluene has also been investigated by VPO and the experimental results interpreted by the formation of mixed species between both reagents. 相似文献
9.
The present review emphasizes the role of hydrodynamic cavitation (HC) and acoustic cavitation in clean and green technologies for selected fuels (of hydrocarbon origins such as gasoline, naphtha, diesel, heavy oil, and crude oil) processing applications including biodiesel production. Herein, the role of cavitation reactors, their geometrical parameters, physicochemical properties of liquid media, liquid oxidants, catalyst loading, reactive oxygen species, and different types of emulsification and formation of radicals, formation as well as extraction of formed by-products are systematically reviewed. Among all types of HC reactors, vortex diode and single hole orifices revealed more than 95 % desulfurization yield and a 20 % viscosity reduction in heavy oil upgrading, while multi-hole orifice (100 holes) and slit Venturi allowed obtaining the best biodiesel production processes in terms of high (%) yield, low cost of treatment, and short processing time (5 min; 99 % biodiesel; 4.80 USD/m3). On the other hand, the acoustic cavitation devices are likely to be the most effective in biodiesel production based on ultrasonic bath (90 min; 95 %; 6.7 $/m3) and desulfurization treatment based on ultrasonic transducers (15 min; 98.3 % desulfurization; 10.8 $/m3). The implementation of HC-based processes reveals to be the most cost-effective method over acoustic cavitation-based devices. Finally, by reviewing the ongoing applications and development works, the limitations and challenges for further research are addressed emphasizing the cleaner production and guidelines for future scientists to assure obtaining comprehensive data useful for the research community. 相似文献
10.
This article studies the applicability of a new technique in determining the interfacial shear rheology properties of surface active compounds relevant to the petroleum industry. It presents the theory behind the determination of the rheological parameters and the results of tests performed on a set of petroleum related compounds (asphaltenes, tetra-acid model compound, fatty acid, and surfactant). It is concluded that this technique is not mature enough to determine the properties of the studied compounds. 相似文献