Photoinduced Reductive Decomposition of Perflurooctanoic Acid in Water: Effect of Temperature and Ionic Strength          下载免费PDF全文

Chaojie Zhang  Yan Qu  Xiaoyun Zhao  Qi Zhou 《洁净——土壤、空气、水》2015,43(2):223-228

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Ultraviolet observations of Phoebe from the Cassini UVIS     

Amanda R. Hendrix  Candice J. Hansen 《Icarus》2008,193(2):323-333

Observations of Saturn's distant moon Phoebe were made at far-ultraviolet (FUV) (1100-1900 Å) and extreme-ultraviolet (EUV) (600-1100 Å) wavelengths by the Cassini Ultraviolet Imaging Spectrograph (UVIS) during the Cassini spacecraft flyby on June 11, 2004. These are the first UV spectra of Phoebe and the first detection of water ice on a Solar System surface using FUV wavelengths. The characteristics of water ice in the FUV are presented, and Hapke models are used to interpret the spectra in terms of composition and grain size; the use of both areal and intimate mixing models is explored. Non-ice species used in these models include carbon, ice tholin, Triton tholin, poly-HCN and kerogen. Satisfactory disk-integrated fits are obtained for intimate mixtures of ∼10% H₂O plus a non-ice species. Spatially resolved regions of higher (∼20%) and lower (∼5%) H₂O ice concentrations are also detected. Phoebe does not display any evidence of volatile activity. Upper limits on atomic oxygen and carbon are 5×¹⁰¹¹ and 2×¹⁰¹² atoms/cm², respectively, for solar photon scattering. The UVIS detection of water ice on Phoebe, and the ice amounts detected, are consistent with IR measurements and contribute to the evidence for a Phoebe origin in the outer Solar System rather than in the main asteroid belt.  相似文献   

The albedo dichotomy of Iapetus measured at UV wavelengths     

Amanda R. Hendrix  Candice J. Hansen 《Icarus》2008,193(2):344-351

The dramatic hemispheric dichotomy in albedo displayed by Saturn's moon Iapetus has intrigued astronomers for centuries. Here we report on far-ultraviolet observations of Iapetus' bright and dark terrains from Cassini. We compare the reflectance spectra of Iapetus's dark terrain, Hyperion and Phoebe and find that both Phoebe and Hyperion are richer in water ice than Iapetus' dark terrain. Spectra of the lowest latitudes of the dark terrain display the diagnostic water ice absorption feature; water ice amounts increase within the dark material away from the apex (at 90° W longitude, the center of the dark leading hemisphere), consistent with thermal segregation of water ice. The water ice in the darkest, warmest low latitude regions is not expected to be stable and may be a sign of ongoing or recent emplacement of the dark material from an exogenic source.  相似文献   

Characterization of Dissolved Organic Matter in Lake Baiyangdian Using Spectroscopic Techniques and Multivariate Statistical Analysis          下载免费PDF全文

Jun Cui  Dong‐hai Yuan  Xu‐jing Guo  Lian‐sheng He  Jiang‐wei He  Hai‐yan Li  Jun‐qi Li 《洁净——土壤、空气、水》2016,44(11):1444-1452

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用于太阳紫外辐射测量传感器的设计   总被引：1，自引：0，他引：1  

王晶  王项南  石建军  李超 《海洋技术学报》2008,27(4)

介绍了太阳紫外辐射的测量原理,为了提高入射光学系统的余弦响应特性而设计的余弦漫射器,以及等效辐射平面位置的计算方法。设计了适用于海滨浴场等场所的太阳紫外线辐射传感器的光学系统结构,研制了试验样机,开展了相应的试验,并对试验结果进行了分析。  相似文献   

Estimation of the <Emphasis Type="Italic">in situ</Emphasis> Ultraviolet-A absorption of seawater by a simple irradiance inversion model     

Takafumi Hirata 《Journal of Oceanography》2008,64(4):561-566

An irradiance inversion model to estimate the in situ absorption coefficient of seawater has been developed for the Ultraviolet-A (UVA) wavelength domain. Input parameters are sun angle and the up-and downward planar irradiances measured for at least two depths. The present method does not require seawater to be sampled, and is a discrete wavelength method which returns the absorption coefficient at a given wavelength from the irradiances measured at that wavelength without assuming a spectral shape of any optical properties a priori. Comparison between the model results and spectrophotometric measurements shows that the model is practically useful when cloud cover in the atmosphere is ≤ 50%. According to the present method, measurements of the irradiances enable simultaneous observation of the in situ underwater UVA radiation level and the absorption capacity of bulk seawater using a radiometer.  相似文献   

What SDO tells us about structure and evolution of coronal bright points     

N. V. Karachik  E. Minenko  I. Sattarov  A. A. Pevtsov  C. T. Sherdonov 《Astronomische Nachrichten》2014,335(10):1037-1042

Using magnetograms and coronal images from two instruments on board the Solar Dynamics Observatory (SDO), we study structure and evolution of a limited number of coronal bright points (CBPs). Our results show that the relation between CBPs and their magnetic footpoints is not simple. In some cases, CBP may appear as a bright portion of a larger loop (with clearly identifiable footpoints), and in some cases, an isolated CBP may develop between magnetic poles, which might not be the closest ones to each other or which might not be involved in the magnetic flux cancellation. We suggest that the magnetic connectivity responsible for formation of isolated coronal bright points is governed by the orientation of the large‐scale magnetic field. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Simulation of Titan haze formation using a photochemical flow reactor: The optical constants of the polymer     

Buu N. Tran  James P. Ferris  Peter D. Persans 《Icarus》2003,165(2):379-390

Solar UV is the principal energy source impinging the atmosphere of Titan while the energy from the electrons in Saturn's magnetosphere is less than 0.5% of the UV light. Titan haze analogs were prepared by the photolysis of a mixture of gases that simulate the composition of its atmosphere (nitrogen, methane, hydrogen, acetylene, ethylene, and cyanoacetylene). The real (n) and imaginary (k) parts of the complex refractive index of haze analogs formed from four different gas mixtures were calculated from the spectral properties of the solid polymer in UV-visible, near infrared and infrared wavelength spectral regions. The value of n was constant at 1.6±0.1 throughout the 0.2-2.5 μm region. The variation of k with wavelength for the values derived for Titan has a lower error than the absolute values of k so the more significant comparisons are with the slopes of the k(λ) plots in the UV-VIS region. Three of the photochemical Titan haze analogs had slopes comparable to those derived for Titan from the Voyager data (Rages and Pollack, 1980, Icarus 41, 119-130; McKay and Toon, 1992, in: Proceedings of the Symposium on Titan, in: ESA SP, Vol. 338, pp. 185-190). The slopes of the k(λ) plots for haze analogs prepared by spark discharge (Khare et al., 1984, Icarus 60, 127-137) and plasma discharge (Ramirez et al., 2002, Icarus 156, 515-529) were also comparable to Titan's. These finding show that the k(λ) plots do not differentiate between different laboratory simulations of atmospheric chemistry on Titan in the UV-VIS near IR region (0.2-2.5 microns). There is a large difference between the k(λ) in the infrared between the haze analogs prepared photochemically and analogs prepared using a plasma discharges (Khare et al., 1984, Icarus 60, 127-137; Coll et al., 1999, Planet. Space Sci. 47, 1331-1340; Khare et al., 2002, Icarus 160, 172-182). The C/N ratio in the haze analog prepared by discharges is in the 2-11 range while that of the photochemical analogs is in the 18-24 range. The use of discharges and UV light for initiating the chemistry in Titan's atmosphere is discussed.  相似文献   

Evaluation of Estrogenic Activity and Measurement of EDCs in Wastewater Treatment Plants     

B. C. Lee  J. Y. Jung  H. K. Kim 《中国海洋大学学报(英文版)》2006,5(4):351-356

1IntroductionDuringthe past several years,concern hasincreasedover the potential pollution of watershed by estrogeniccompounds,including steroidal hormones fromhumanand ani mal sources.Effluents from wastewater treat-ment plants are sources of endocrine-d…  相似文献   

The O iv and S iv intercombination lines in the ultraviolet spectra of astrophysical sources     

F. P. Keenan  S. Ahmed  T. Brage  J. G. Doyle  B. R. Espey  K. M. Exter  A. Hibbert  M. T. C. Keenan  M. S. Madjarska  M. Mathioudakis  D. L. Pollacco 《Monthly notices of the Royal Astronomical Society》2002,337(3):901-909

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