The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modif...The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modification is a function of the solar radiation＇s path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle （SZA）. The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University （SVU） meteorological research station （26.20°N, 32.75°E） car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB （UVBe^d and broadband solar radiation （Gext） were estimated. Consequently, the hemispherical transmittance of UVB （KtuvB） and the hemispherical transmittance of global solar radiation （Kt） were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA （KtuvB=-a（SZA）＋b） for very narrow Kt-ranges （width of ranges was 0.01） was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation （R） between KtuvB and SZA was equal to -0.83 for Kt= 0.76.展开更多
Cloud point extraction （CPE） processes with two silicone surfactants, Dow Coming DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbo...Cloud point extraction （CPE） processes with two silicone surfactants, Dow Coming DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbons （PAHs）： anthracene, phenanthrene and pyrene. For all cases, the volumes of surfactant-rich phase obtained by two silicone surfactants were very small, i.e. a lower water content in the surfactant-rich phase was obtained. For example, less than 3% of the initial solution was obtained in a 1% （by mass） surfactant solution, which was much smaller than that of TX-114 in the same surfactant concentration. And TX-114 is known as a high compact surfactant-rich phase among most nonionic surfactants, thus the comparison showed that an excellent enrichment was ensured in the analysis application by the CPE process with the silicone surfactants, and the lower water content obtained in the surfactant-rich phase is also important in the large scale water treatment. The influences of additives and phase separation methodology on the recovery of PAHs were discussed. Comparing with DC-193, DC-190 has a lower cloud point and a higher recovery （near 100%） of all the three PAHs in same surfactant concentration, which was required for application as a preconcentration process prior to HPLC system. However the DC-190 solution is hard to be phase separated only by heating, whereas DC-193 has a relative higher phase separating speed by heating, but a high cloud point （around 360K） limits its application. Due to the phase separation by heating is the only method of CPE suitable to the large scale water treatment, the mixtures of two silicone surfacrants solutions were investigated in this study. A solution containing 1% of mixed DC-190 and DC-193 （in the ratio of 90 ： 10） removed anthracene, phenanthrene and pyrene near 100% with a relative low cloud point and quick phase separating speed.展开更多
基金supported by the Deanship of Scientific Research from King Saud University
文摘The atmosphere protects humans, plants, ani- mals, and microorganisms from damaging doses of ultra- violet-B （UVB） solar radiation （280-320 nm） because it modifies the UVB reaching the Earth＇s surface. This modification is a function of the solar radiation＇s path length through the atmosphere and the amount of each attenuator along the path length. The path length is deter- mined by solar zenith angle （SZA）. The present work ex- plains the dependence of hemispherical transmittance of UVB on SZA. The database used consists of five years of hourly UVB and global solar radiation measurements. From 2001 to 2005, the South Valley University （SVU） meteorological research station （26.20°N, 32.75°E） car- ried out these measurements on a horizontal surface. In addition, the corresponding extraterrestrial UVB （UVBe^d and broadband solar radiation （Gext） were estimated. Consequently, the hemispherical transmittance of UVB （KtuvB） and the hemispherical transmittance of global solar radiation （Kt） were estimated. Furthermore, the UVB redaction due to the atmosphere was evaluated. An analy- sis of the dependence between KtuvB and SZA at different ranges of Kt was performed. A functional dependence between KtuvB and SZA （KtuvB=-a（SZA）＋b） for very narrow Kt-ranges （width of ranges was 0.01） was devel- oped. The results are discussed, and the sensitivity of AKtuvB to △SZA for very narrow Kt-ranges was studied. It was found that the sensitivity of △KtUVB to ASZA slightly increases with increased Kt, which means KtuvB is sensi- tive to SZA as Kt increases. The maximum correlation （R） between KtuvB and SZA was equal to -0.83 for Kt= 0.76.
文摘Cloud point extraction （CPE） processes with two silicone surfactants, Dow Coming DC-190 and DC-193, were studied as preconcentration and treatment for the water polluted by three trace polycyclic aromatic hydrocarbons （PAHs）： anthracene, phenanthrene and pyrene. For all cases, the volumes of surfactant-rich phase obtained by two silicone surfactants were very small, i.e. a lower water content in the surfactant-rich phase was obtained. For example, less than 3% of the initial solution was obtained in a 1% （by mass） surfactant solution, which was much smaller than that of TX-114 in the same surfactant concentration. And TX-114 is known as a high compact surfactant-rich phase among most nonionic surfactants, thus the comparison showed that an excellent enrichment was ensured in the analysis application by the CPE process with the silicone surfactants, and the lower water content obtained in the surfactant-rich phase is also important in the large scale water treatment. The influences of additives and phase separation methodology on the recovery of PAHs were discussed. Comparing with DC-193, DC-190 has a lower cloud point and a higher recovery （near 100%） of all the three PAHs in same surfactant concentration, which was required for application as a preconcentration process prior to HPLC system. However the DC-190 solution is hard to be phase separated only by heating, whereas DC-193 has a relative higher phase separating speed by heating, but a high cloud point （around 360K） limits its application. Due to the phase separation by heating is the only method of CPE suitable to the large scale water treatment, the mixtures of two silicone surfacrants solutions were investigated in this study. A solution containing 1% of mixed DC-190 and DC-193 （in the ratio of 90 ： 10） removed anthracene, phenanthrene and pyrene near 100% with a relative low cloud point and quick phase separating speed.
