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61.
62.
Sepideh Maaref 《Journal of Dispersion Science and Technology》2018,39(5):721-733
Water-in-oil emulsion usually forms during waterflooding in some heavy oil reservoirs. The composition and salinity of the injected water critically affect the w/o emulsion droplet size distribution, which control the emulsion stability and emulsion flow in porous media. The aim of the present work is to assess the effect of different sea water salinities on w/o emulsion stability through microscopic imaging. Therefore, w/o emulsions were prepared with different sea water samples, which were synthesized to resemble Persian Gulf, Mediterranean, Red Sea, and North Sea water samples. The results showed that log-normal distribution function predicts very well the experimental data to track the emulsion droplet size distribution, and then it was used for the emulsion stability analysis. It was found that among the four emulsion samples, North Sea emulsion with the lowest NaCl and TDS concentration of 24.12?g/L and 34.44?g/L remained stable up to almost 24 hours, while Red sea emulsion with the highest NaCl and TDS concentration of 32.39?g/L and 41?g/L became unstable after 6-hour period. This indicated that as the brine concentration increases, the w/o emulsion droplets would be larger due to the higher rate of aggregation and coalescence, and the emulsion stability decreases. 相似文献
63.
Kenji Takizawa Akifumi Takahashi Kazuaki Tokuhashi Shigeo Kondo Akira Sekiya 《Journal of fluorine chemistry》2008,129(8):713-719
Burning velocity measurements of six types of fluoropropanes including structural isomers were carried out in order to understand the flammability of hydrofluorocarbons (HFC). The burning velocity (Su) was determined by applying a spherical flame model to the pressure rise during combustion, which was measured at room temperature and at initial pressures of 80-107 kPa over a wide range of HFC/air concentrations. The maximum Su of 1-fluoropropane (HFC-281fa), 2-fluoropropane (HFC-281ea), 1,3-difluoropropane (HFC-272fa), 2,2-difluoropropane (HFC-272ca), 1,2,3-trifluoropropane (HFC-263ea), and 1,1,1-trifluoropropane (HFC-263fb) was 35.0, 31.8, 31.9, 21.2, 25.7, and 14.5 cm s−1, respectively. Note that the maximum Su of HFC-263ea was appreciably higher than that of HFC-272ca, which shows the importance of the F-atom distribution, as well as of the F/H ratio in the HFC molecule. The results of equilibrium calculation for these HFCs showed that Su is positively correlated with the flame temperature and the concentrations of the active chain carriers H and OH in the flame. We conducted a trial to interpret the magnitude of Su by means of the effects of substituents for C1-C3 HFCs. As a result, it has been found that the order of inhibition efficiency for Su decreases in the order of CF3 > CF2 > CF. 相似文献
64.
Different stereoisomers of active molecules often cause different physiological responses and hence pose a challenge for their identification. This study involves perceptive fragmentation behavior of newly isolated cassane butenolides, caesalpinolide A [1] and caesalpinolide B [2] (epimeric at the hemiketal position) by tandem MS. The electrospray ionization-mass spectrometry (ESI-MS)/collision-induced dissociation (CID; ESI-MS(2) and ESI-IT-MS(n)) were investigated. The effect of orientations of hemiketal hydroxyl at C-12 was clearly observed in the mass spectrum. Tandem mass spectra of 1, 1(A) or 2, 2(A) show stereospecific fragmentation resulting in significant abundance dissimilarity of [MH - H(2)O](+) as well as differences in fragmentation pathway. Both of these pathways seem to be influenced by the stereochemistry of the molecule. The differentiation can be clearly visualized from the [M + H - H(2)O](+)/[M + H](+) ratio of the two isomers where beta-isomer 2 was found to be five times higher than that of alpha-isomer 1 in full scan liquid chromatography-electrospray ionization mass spectrometry(LC-ESI-MS). In high-energy CID, the mass fingerprint of 1, 2, 1(A), and 2(A) was found to be different from one another. 相似文献
65.
66.
非银盐感光材料与卤化银感光材料相比具有很高的分辨力,但灵敏度较低,限制了它的应用范围。因此,如何提高非银盐感光材料的灵敏度一直是非常活跃的研究领域。 相似文献
67.
本文研究了苯酚类(A),双酚类(B),对苯二酚类(C),色满类(D)和双螺色满类(E)抗氧化剂的性能。通过循环伏安法测定了它们的氧化电位;用类似Stern-Volmer关系图求得各抗氧化剂和单重态氧的反应速率常数。抗氧化剂的氧化电位越小,和单重态氧的反应速率常数越大,对品红甲亚胺染料影像的防褪色效果越好,进一步证实了染料褪色的光氧化反应机理。在这些抗氧化剂中,它们的防褪色效果依次为D>E>C>B>A。 相似文献
68.
A stereoscopic digital speckle photography system for 3-D displacement field measurements 总被引:7,自引:0,他引:7
Stereoscopic digital speckle photography offers a technique to measure object shapes and 3-D displacement fields in experimental mechanics. The system measures the displacement of a random white light speckle pattern, which somehow is present on the object surface, using digital correlation. This paper describes a general physical model for stereo imaging systems. A camera calibration algorithm, which takes the distortion in the lenses into account, is also presented and evaluated by real experiments. Standard deviations of small deformations as low as 1% of the pixel size for in-plane deformations and 6% of the pixel size for the out-of-plane component are reported. Using the calibration algorithm described, the main source of errors is random errors originating from the correlation algorithm. 相似文献
69.
The importance of technological processes like corrosion, ablation or deposition causes interest in the quantitative monitoring of changes at rough surfaces. Thus, there is a need for effective methods to measure the statistical parameters characterizing changes in the profile or the material composition of such objects. The speckle field scattered from the surface is used as information carrier and its change is measured by correlation. This is realized by sophisticated data acquisition and digital processing techniques. An important issue is the interpretation of the correlation output in terms of statistical parameters describing the surface change. For many random surfaces a geometrical relation between surface profile and optical phase proves satisfactory. This allows to determine the standard deviation of the profile change. For a verification, speckle decorrelation in model surfaces of known deviation is measured. The paper introduces the speckle correlation concept, outlines some history and current setups and describes methods for data evaluation. The reliability of the quantitative interpretation of the speckle decorrelation is demonstrated. The method is illustrated by studies of metal corrosion and material removal in the cleaning of historical objects by laser ablation. 相似文献
70.
叙述了用高速摄影技术研究强流脉冲电子束与钽金属靶相互作用后靶材的回喷现象,得出了靶材回喷的速度。并且采用EGS4程序和Euler流体力学方程组分别模拟了电子束在靶内的能量沉积和束靶相互作用的动力学过程。实验表明,钽金属靶在强流脉冲电子束轰击下,回喷靶材的轴向速度大于2.9 mm/μs,而模拟结果表明理想情况下回喷靶材自由面的轴向速度可达9.7 mm/μs。实验和理论计算为阻挡回喷靶材的快门设计提供了必要的参数。 相似文献