Simultaneous Measurements of Fluorescence and Beam Attenuation: Instrument Characterization and Interpretation of Signals from Stratified Coastal Waters

1999 ◽  
Vol 48 (1) ◽  
pp. 51-58 ◽  
Author(s):  
D. McKee ◽  
A. Cunningham ◽  
K. Jones
Keyword(s):  
Coastal Waters ◽  
Simultaneous Measurements ◽  
Beam Attenuation

scholarly journals Spectral Relations of Hydro-Optical Characteristics in Coastal Waters of the South Coast of Crimea

2021 ◽  
Author(s):  
V. I. Mankovsky ◽  
E. V. Mankovskaya ◽  
◽  
Keyword(s):  
Attenuation Coefficient ◽  
Coastal Waters ◽  
Deep Sea ◽  
Secchi Depth ◽  
Measurement Data ◽  
South Coast ◽  
Optical Measurements ◽  
The South ◽  
Beam Attenuation ◽  
Beam Attenuation Coefficient

The article studies interrelations of the beam attenuation coefficient in different spectrum regions and spectral relations of beam attenuation coefficient to the Secchi depth in the coastal waters of the South Coast of Crimea. The data were used of in situ optical measurements obtained in 2008–2014 from a stationary oceanographic platform installed in the coastal waters of the South Coast of Crimea near the village of Katsiveli. According to the measurement data the relation was determined of the beam attenuation coefficient in eight parts of the spectrum in the wavelength range of 416–640 nm to the Secchi depth, which varies from 6 m to 17.5 m. Spectral distributions of the beam attenuation coefficient at different Secchi depths in coastal and deep sea waters were compared. As a result, it is concluded that the relationships between the spectral attenuation coefficient and the Secchi depth in coastal waters are not applicable to deep sea waters. It is shown that the feature of such equations in coastal waters is related to the higher concentration of fine suspended matter in them. Intercorrelation parameters were calculated of beam attenuation coefficients in different spectrum regions in coastal waters. High correlation coefficients make it possible to reconstruct distribution of the attenuation coefficient in a wide spectral range based on measurements at one wavelength in any spectrum region. The optimal spectral region to measure the beam attenuation coefficient is 468–527 nm.

Methylamine vanadate (nanovan) negative stain

1994 ◽  
Vol 52 ◽  
pp. 132-133
Author(s):  
James F. Hainfeld ◽  
Daniel Safer ◽  
Joseph S. Wall ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Low Dose ◽  
Biological Molecules ◽  
Positive Staining ◽  
Signal To Noise ◽  
Negative Stain ◽  
Beam Attenuation ◽  
Coarse Grains ◽  
Lower Contrast

Uranyl and tungstate compounds have found favor as negative stains because of their high scattering power relative to biological molecules. However, other properties, such as specimen preservation, resistance to alterations or crystallization in the electron beam, and signal to noise (S/N) ratio, are also important. It may be that lower density materials may have advantages in these areas. A new negative stain, methylamine vanadate, CH3 NH2.VO3 ("NanoVan"), offers a near physiological pH of 8, similar to phosphotungstate (pH 7) with much smoother background. It is also very stable in the electron beam with minimal granulation at a dose of l04 el / nm2 . The resolution obtainable with vanadate appears to be comparable to uranyl at low dose, but superior at higher dose where uranyl forms coarse grains (see Fig. 1). Problems with uranyl such as unwanted positive staining and need for pH below 4 can be avoided. The lower contrast permits use of thicker stain embedment for better preservation and less flattening without excessive beam attenuation.

The Clearance of 133Xenon from the Liver Intraportal Injection in Man

1965 ◽  
Vol 05 (03) ◽  
pp. 241-245 ◽  
Author(s):  
K.-F. Aronsen ◽  
B. Ericsson ◽  
A. Fajgelj ◽  
S.-E. Lindell
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Hepatic Blood Flow ◽  
Scintillation Detectors ◽  
Disappearance Rate ◽  
Simultaneous Measurements

Summary 133Xe dissolved in saline was injected into the portal vein in man. Hepatic blood flow was calculated from the disappearance rate of 133Xe recorded with scintillation detectors placed over the liver. The results are discussed and related to simultaneous measurements of the pressure in the portal vein.

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