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Cyanobacteria in Inland Waters: Remote Sensing
Published in Yeqiao Wang, Fresh Water and Watersheds, 2020
Li and Song [16] systematically compared the performance of various empirical, semi-empirical, and semi-analytical PC algorithms with in situ measured reflectance spectra for three central Indiana reservoirs: Eagle Creek, Geist, and Morse. For these three reservoirs, an ASD FieldSpec ultraviolet/visible and near-infrared (UV/VNIR) spectroradiometer (Analytical Spectral Devices, Inc., Boulder, CO, USA) was used to measure the remote sensing reflectance above the water surface Rrs(λ) in 2005 and 2006, and an Ocean Optics USB4000 unit (Ocean Optics, Inc., Dunedin, FL, USA) with dual radiometers to measure remote sensing reflectance below the water surface rrs(λ) in 2007, 2008, and 2010, and resulted in a total of 649 water samples for which both in situ spectra and PC concentrations were available. BR650/620, MRBI, NBR, and EIIMIW were compared for their performance, and R2 = 0.54, 0.21, 0.73, and 0.74 were obtained, respectively.
Are Warmer Waters, Brighter Waters?: An Examination of the Irradiance Environment of Lakes and Oceans in a Changing Climate
Published in Donat-P. Häder, Kunshan Gao, Aquatic Ecosystems in a Changing Climate, 2018
In these oligotrophic open ocean, ‘blue’, surface mixed layers there are sharp differences in attenuation between wavelengths. As mentioned previously, this is related to the strong wavelength dependence of attenuation by water molecules. Thus, the effective attenuation coefficient for broadband PAR varies by depth, with stronger attenuation near the surface as the red, green and violet components of sunlight are absorbed, leading to weaker attenuation of the remaining blue irradiance at depth. Moreover, the response of phytoplankton to irradiance is actually dependent on the variable spectral absorption of light by phytoplankton pigments (Neori et al. 1984). Thus, the efficiency of phytoplankton light utilization in subtropical gyres also varies with depth (Letelier et al., 2017). These depth dependencies make it difficult to characterize changes in average mixed layer irradiance due to variation in mixed layer depth. Here, we use changes in average irradiance at 490 nm as an index of PAR availability. Attenuation is usually at the minimum at this wavelength which is widely-used as a reference for ocean optics and remote sensing and is available over the full time-period in both the HOTS and BATS data. Trends in other wavelengths measured were similar but are not presented here for brevity. In the BATS data, we also considered the time series of attenuation at 380 nm as an indicator of UV transparency. No trend analysis of UV transparency was conducted for HOTS since data were only available from 2012.
A study on rhodamine 6G – based fiber-optic sensing system for detection of mercury ion in aqueous environment
Published in Kennis Chan, Testing and Measurement: Techniques and Applications, 2015
A.R. Lee, B.Y. Jung, H.J. Han, Y.I. Kim, B.K. Kim, B.G. Park
All reagents and solvents for the experiment were purchased from Aldrich, and used without further purification. Absorption spectra were measured by an Ocean Optics UV/Vis Spectrometer QE65000. A JEOL ECS-400 NMR spectrometer was used to analyze the structure of the synthetic products, for the sensing material of mercury ion in water solution. 2.2 Synthesis
Optimization of toluene removal over W-doped TiO2 nano-photocatalyst under visible light irradiation
Published in Environmental Technology, 2018
Ali Poorkarimi, Ayoub Karimi-Jashni, Sirus Javadpour
The pure titanium nanoparticles were provided from US research Nanomaterial Incorporation for comparison with tungsten-doped TiO2. Titanium butoxide (Ti(OC4H8)4, Sigma Aldrich, Italy), tungstic acid (H2WO4, Merck, Germany), and hydrogen peroxide (H2O2, Merck, Germany) were used to prepare the tungsten-doped TiO2 via the sol–gel method. Toluene (Merck, Germany, purity >99.9%) was used as air pollutant. Philips TUV 15 watt T8 UV-C light bulb (Philips, Holland) was used as UV source and HITACH 15 watt F15T8/D light bulb (Hitachi, Japan) was used to produce visible light. Spectroscopy of UV and visible light was determined by Ocean Optic HR4000 spectrometer (Ocean Optics, USA). Toluene concentration was measure using Firstcheck+ instrument (Ion Science, UK) equipped with photo ionization detector technology. FirstCheck+ is a portable gas detector, suitable for the detection of a large range of VOCs.
From Single to Multi Mode Lasing: The role of materials revealed in optical simulations
Published in Liquid Crystals, 2022
P.V. Shibaev, P. Fessatidis, A. Roslyak
The lasing experiments were performed as follows. The pulse from the YAG laser (New Wave Research Inc) hits the sample at an angle of 20–30 degrees. The beam is focused on CLC by a long focal length lens allowing the formation of a narrow and lengthy ‘neck’. The spectra were recorded using an Ocean Optics spectrometer collecting light in a relatively narrow cone of 5–10 degrees. It is important to note that quantifying lasing threshold in absolute values lied out of the scope of this study and the focus of this research was on the comparative study of the spectral positions of lasing peaks in ordered and disordered samples.