Uranium values from ion-filter water sampling compared with values from bulk-water sampling

1978 ◽  
Author(s):  
Robert Allen Cadigan ◽  
J. Karen Felmlee
Keyword(s):  
Bulk Water ◽  
Water Sampling ◽  
Ion Filter ◽  
Filter Water

scholarly journals Dynamic flows create potentially habitable conditions in Antarctic subglacial lakes

2021 ◽  
Vol 7 (8) ◽  
pp. eabc3972
Author(s):  
Louis-Alexandre Couston ◽  
Martin Siegert
Keyword(s):  
Bulk Water ◽  
Water Sampling ◽  
Stable Layer ◽  
Microbial Life ◽  
Subglacial Lake ◽  
Physical Conditions ◽  
Dynamic Flows ◽  
Subglacial Lakes ◽  
Ice Water ◽  
The Antarctic

Trapped beneath the Antarctic ice sheet lie over 400 subglacial lakes, which are considered to be extreme, isolated, yet viable habitats for microbial life. The physical conditions within subglacial lakes are critical to evaluating how and where life may best exist. Here, we propose that Earth’s geothermal flux provides efficient stirring of Antarctic subglacial lake water. We demonstrate that most lakes are in a regime of vigorous turbulent vertical convection, enabling suspension of spherical particulates with diameters up to 36 micrometers. Thus, dynamic conditions support efficient mixing of nutrient- and oxygen-enriched meltwater derived from the overlying ice, which is essential for biome support within the water column. We caution that accreted ice analysis cannot always be used as a proxy for water sampling of lakes beneath a thin (<3.166 kilometers) ice cover, because a stable layer isolates the well-mixed bulk water from the ice-water interface where freezing may occur.

scholarly journals Enhancing Sampling of Water Rearrangements on Ligand Binding: A Comparison of Techniques

2021 ◽  
Author(s):  
Yunhui Ge ◽  
David C. Wych ◽  
Marley L. Samways ◽  
Michael E. Wall ◽  
Jonathan W. Essex ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Binding Site ◽  
Md Simulation ◽  
Direct Analysis ◽  
Md Simulations ◽  
Binding Mode ◽  
Bulk Water ◽  
Free Energy Calculations ◽  
Water Sampling ◽  
Ligand Interactions

Water often plays a key role in protein structure, molecular recognition, and mediating protein-ligand interactions. Thus, free energy calculations must adequately sample water motions, which often proves challenging in typical MD simulation timescales. Thus, the accuracy of methods relying on MD simulations ends up limited by slow water sampling. Particularly, as a ligand is removed or modified, bulk water may not have time to fill or rearrange in the binding site. In this work, we focus on several molecular dynamics (MD) simulation-based methods attempting to help address water motions and occupancies: BLUES, using nonequilibrium candidate Monte Carlo (NCMC); grand, using grand canonical Monte Carlo (GCMC); and normal MD. We assess the accuracy and efficiency of these methods in sampling water motions. We selected a range of systems with varying numbers of waters in the binding site, as well as those where water occupancy is coupled to the identity or binding mode of the ligand. We analyzed water motions and occupancies using both clustering of trajectories and direct analysis of electron density maps. Our results suggest both BLUES and grand enhance water sampling relative to normal MD and grand is more robust than BLUES, but also that water sampling remains a major challenge for all of the methods tested. The lessons we learned for these methods and systems are discussed.

STEM measurement of subcellular water distributions

1993 ◽  
Vol 51 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
S.Q. Sun ◽  
S-L. Shi ◽  
R.A. Buchanan ◽  
S.B. Andrews
Keyword(s):  
Water Content ◽  
Internal Standard ◽  
Dry Weight ◽  
Dry Mass ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Bulk Water ◽  
Inelastic Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

Further advances in dissolved oxygen micro analysis. I. Small-scale water sampling vessels and amperometric titrations

1959 ◽  
Vol 9 (12) ◽  
pp. 642-645
Author(s):  
E. C. Potter ◽  
G. E. Everitt
Keyword(s):  
Dissolved Oxygen ◽  
Small Scale ◽  
Water Sampling ◽  
Micro Analysis

Bulk water treatment unit performance: For the cameras or the community?

Waterlines ◽  
2012 ◽  
Vol 31 (1-2) ◽  
pp. 53-66 ◽  
Author(s):  
Richard Luff ◽  
Caetano Dorea
Keyword(s):  
Water Treatment ◽  
Bulk Water ◽  
Treatment Unit ◽  
Unit Performance

PVDF Emblem⁄Micro Filter Water Recycling System

2008 ◽  
Vol 62 (6) ◽  
pp. 700-703
Author(s):  
Makoto Matsushita ◽  
Yoshiharu Numata
Keyword(s):  
Water Recycling ◽  
Recycling System ◽  
Filter Water
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