The inferior mirage from road surfaces is a common phenomenon, which can be easily seen in everyday life. It has been recognized in the literature as a light refraction phenomenon due to the refractive index gradient caused by the temperature gradient in the air strata above the road surfaces. However, it was also suggested that the mirage is just a phenomenon of specular reflection at grazing incidence. Because of the lack of reasonable and quantitative evidence, the generally accepted light refraction theory has not yet been refuted. Here we show some mirror-like reflection images captured from a road surface stretch in Yujiashan North Road, Wuhan, China, when there was no obvious temperature gradient on or above the road, measured on a winter day in December 2009. This provided direct evidence to doubt the temperature induced light refraction mechanism of the inferior mirage. Furthermore, the critical grazing angle of about 0.2° to the road plane where the mirror-like reflection appears could not make the rough surface scatter incident light as a smooth surface according to the Rayleigh criterion. Therefore the phenomenon is a mirrorlike observation effect of scattering from the surface, which cannot be entirely explained by light refraction via air strata. The results demonstrate that the image-formation mechanism and the observer-based-analysis method shown here potentially offer a means of understanding a wide range of scattering phenomena from rough surfaces at grazing angle; for example, the superior mirages of unusual brightness occasionally observed over frozen lakes and the off-specular reflection phenomenon.
An iron/copper bimetallic catalytic oxidation desulfurization system was constituted by adding N-methyl pyrrolidone (NMP) and CuCl 2 aqueous solution to an iron-based ionic liquid (Fe-IL) for the removal of hydrogen sulfide from industrial gas streams. The desulfurizer and its sulfur products were characterized using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Static desulfurization experiments were conducted to investigate the absorption pattern of the system for H 2 S. The addition of NMP and water effectively reduced the acidity and viscosity of the system and improved the gas-liquid mass transfer efficiency. The introduction of CuCl 2 increased the oxidation potential of the solution and enabled Fe 3+ to efficiently catalyze the oxidation of H 2 S to produce monomeric S. The synergistic catalytic oxidation between Fe 3+ /Cu 2+ is the main reason why the system can maintain a high degree of purification over a long period.
Under neutral conditions, a variety of S-alkylisothiourea salts were smoothly converted into the corresponding sulfonyl chlorides through tert-butyl chlorite mediated oxidative chlorination in good to excellent yields after simple purification. In addition to the environmental and procedural advantages of this method, the neutral conditions potentially make it applicable to substrates that bear acid-sensitive functional groups. For example, the Cbz-protected 2-aminoethanesulfonyl chloride could be synthesized in moderate to good yields under the current neutral conditions, and the acid-sensitive Cbz-protecting group was not affected.
The high‐sulfur gas sweetening process is energy consuming. To analyze its energy efficiency effectively, and look for ways to improve this process, a novel energy‐efficiency evaluation method based on the yield‐energy‐selectivity and efficiency coefficient methods was proposed. First, the yield, energy, and selectivity are selected as evaluation indicators to establish the yield‐energy‐selectivity evaluation model. Then, the coefficient and score of each indicator were determined by using the analytical hierarchy process and efficacy coefficient method, respectively. Finally, the proposed energy‐efficiency evaluation method was applied to the actual high‐sulfur gas sweetening process. The evaluation results were in good agreement with those obtained by actual experiences.
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