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Surfactants are widely used in the tertiary recovery of oilfields， and it is of great significance to study the mechanism of surfactant flooding from the microscopic point of view. In recent years， molecular dynamics （MD） simulation has become essential for oil and gas field development research. The use of MD simulation to study surfactants has become a hot spot. Through MD simulation， the numerical solutions of Newton’s equations are calculated for all the moving particles in the system， and the change in atomic positions with time is analyzed， from which some laws are found. MD simulation can be used to study the microscopic behavior of surfactant molecules to explore the properties of surfactant molecules and the microscopic flooding mechanism. MD simulation of the movement and aggregation state of surfactants at the interface and the analysis of the influence of surfactant molecules at the interface on the interfacial system are of some guiding significance for the field application of surfactants. To this end， based on the principle overview of MD simulation， firstly， the force field， boundary conditions， system types， and numerical algorithms in MD simulation are summarized； secondly， the microscopic mechanisms of MD simulation of surfactant flooding are highlighted， including the reduction of oil-water interfacial tension， the change in surface wettability， the increase in interfacial charge and emulsification， etc.； then， examples of the application of MD simulation in surfactant flooding are presented. Finally， the development directions of MD simulation technology in surfactant flooding are proposed， including the flooding environment similar to production， the design of new surfactants， the relationship between theory and experiment， the selection of molecular force field and potential energy model， and the research and development of composite and multifunctional integrated surfactants.

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Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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In order to investigate the improvement of the strength and microstructure of peat soil in the Dianchi area Kunming, Yunnan province by cement and high-calcium fly ash, the modified soil with the peat soil and cement, fly ash and high-calcium fly ash in Dianchi was studied, and standard consolidation test, direct shear test, unconfined compressive strength test, SEM scanning electron microscopy test, energy spectrum analyst an XRD test were carried out. Through the correlation and comparison between the macroscopic physical and mechanical properties and microstructure characteristics, the optimal improvement scheme was obtained. The results show that the compression modulus, cohesive force and unconfined compressive strength of the mixed modified soil increase with the addition of cement, fly ash and high-calcium fly ash. The improvement effect of mixed addition on peaty soil is better than that of single addition, and the improvement effect is the best when the cement content of high calcium fly ash is 6%+12%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Xinyang Normal University Natural Science Edition is the property of Journal of Xinyang Normal University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The method of combining reference objective and numerical fitting is established to solve the phase distortion of off-axis digital holography. Because of the optical curvature difference caused by the objective, the pre-amplified digital holographic microscopy system often produces additional phase factors. By introducing the same reference objective in the reference beam path, the phase distortion due to curvature problems is initially eliminated. With the addition of the reference objective, phase distortion mainly comes from three aspects: the numerical simulation of plane reference light is used in diffraction calculation, and a phase distortion is generated with the off-axis structure having a spatial angle; the actually recorded hologram causes a secondary phase distortion because the object wave passes through the pre-amplified objective;the other optical components in the optical path form aberrations, failing to get the correct 3 D shape of the microstructure. The entire phase surface is fitted by a polynomial, and the difference between the phase surface and the fitted surface is used to extract the true phase distribution of the sample. With only one hologram, multiple phase distortions are automatically compensated by a polynomial fit. The USAF resolution plate being used as the microstructure pattern for measurement, the accuracy and effectiveness of the method are verified. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Jianzhu Cailiao Xuebao: Journal of Building Materials is the property of Journal of Building Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To analyze the clinical data of patients with olfactory dysfunction after endoscopic or microscopic endonasal transsphenoidal approach,and to screen out the possible related factors,to guide clinical diagnosis and treatment,and to improve the patients' quality of life. Method: In the retrospective study,we analyze patients' data,and follow up them with telephone,records the olfactory levels before and after surgery. In the prospective study,five odors were applied to test the olfactory function before the surgery,then one week,3 weeks and 6 weeks after that. The results were statistically analyzed. Result: In the retrospective study,olfactory dysfunction occurred in 67.74%,47.37%in MTS group and ETS group. The olfactory disorder had no significant difference ( P >0.05) among MTS group and ETS group after surgery. And the analysis of factors showed no significant difference. In the prospective study,there is significant difference between the preoperative results and postoperative results about the operative side and nonoperative side in ETS group and MTS group ( P <0.05). In all results,there is no significant difference between operative side and nonoperative side in ETS group and MTS group ( P >0.05). Conclusion: There is olfactory dysfunction after transsphenoidal surgery to resect pituitary adenomas. To prepare the nasal condition well preoperatively,protect the nasal structure intraoperatively and aplicate appropriate treatment postoperatively may reduce the incidence of olfactory disorder., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)