Near Surface Characterization of an Impinging Elliptic Jet Array

1999 ◽  
Vol 121 (2) ◽  
pp. 384-390 ◽  
Author(s):  
Simona C. Arjocu ◽  
James A. Liburdy
Keyword(s):  
Surface Characterization ◽  
Large Scale ◽  
Near Surface ◽  
Large Scale Structures ◽  
Aspect Ratios ◽  
Naturally Occurring ◽  
Turbulence Velocity ◽  
Axis Switching ◽  
Jet Array

In this study naturally occurring large-scale structures and some turbulence characteristics within an impinging jet array are investigated. The dynamics of a three-by-three elliptic jet array are analyzed relative to the flow structures within the array. With applications to electronic component cooling, low Reynolds number conditions, Re = 300 to 1500, are presented. Two jet aspect ratios are used, 2 and 3, with identical jet hydraulic diameters and jet-to-jet space. The effects of impinging distance are studied in the range of one to six jet hydraulic diameters. Flow visualization and PIV are used for the identification of structures and quantitative analysis. These results are used to evaluate the integrated surface layer vorticity, Γ*, which is shown to depend on the jet aspect ratio and impingement distance. Also, a transport coefficient is presented, based on a turbulence velocity and length scales. This coefficient is shown to experience a maximum value versus impingement distance that coincides with the location of axis switching.

The Effect of Aspect-Ratio on the Development of the Large-Scale Structures in the Three-Dimensional Wall Jet

2005 ◽  
Author(s):  
Joseph W. Hall ◽  
Daniel Ewing
Keyword(s):  
Aspect Ratio ◽  
Large Scale ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Decomposition Analysis ◽  
Wall Pressure ◽  
Symmetric Mode ◽  
Large Scale Structures ◽  
Aspect Ratios ◽  
Scale Structures

The development of the large-scale structures in three-dimensional wall jets exiting rectangular nozzles with aspect-ratios of 1 and 4 was investigated using simultaneous measurements of the fluctuating wall pressure across the jet. The pressure fluctuations in the jets were asymmetric and caused the fluctuating wall pressure to be poorly correlated across the jet centerline. A Proper Orthogonal Decomposition analysis indicated that both the first and second modes make similar contributions to the variance of the fluctuating pressure, and were symmetric and antisymmetric, respectively, and the interplay between these modes caused the asymmetry in the instantaneous pressure fluctuations across the jet centreline. A wavelet analysis of the instantaneously reconstructed pressure fields indicated that the fluctuations were predominantly in two frequency bands near the jet centerline, but were only contained in one band on the outer lateral edges of the jet, indicating there were two different large-scale motions present. The development of large-scale structures in the two jets initially differed in the intermediate field with the antisymmetric mode being more prominent in the square jet and the symmetric mode being more prominent in the larger aspect-ratio jet. Further downstream, the symmetric mode was more prominent in both jets.

Depth and properties of freshwater export from the Greenland Ice Sheet modulated by ice-ocean processes

2020 ◽  
Author(s):  
Donald Slater ◽  
Fiamma Straneo
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Regional Variability ◽  
Near Surface ◽  
Fjord Circulation ◽  
Ocean Reanalyses ◽  
Freshwater Export ◽  
Ocean Processes

<p>Freshwater export from the Greenland Ice Sheet to the surrounding ocean has increased by 50% since the early 1990s, and may triple over the coming century under high greenhouse gas emissions. This increasing freshwater has the potential to influence both the regional and large-scale ocean, including marine ecosystems. Yet quantification of these impacts remains uncertain in part due to poor characterization of freshwater export, and in particular the transformation of freshwater around the ice sheet margin by ice-ocean processes, such as submarine melting, plumes and fjord circulation. Here, we combine in-situ observations, ocean reanalyses and simple models for ice-ocean processes to estimate the depth and properties of freshwater export around the full Greenland ice sheet from 1991 to present. The results show significant regional variability driven primarily by the depth at which freshwater runoff leaves the ice sheet. Areas with deeply-grounded marine-terminating glaciers are likely to export freshwater to the ocean as a dilute mixture of freshwater and externally-sourced deep water masses, while freshwater from areas with many land-terminating glaciers is exported as a more concentrated mixture of freshwater and near-surface waters. A handful of large glacier-fjord systems dominate ice sheet freshwater export, and the vast majority of freshwater export occurs subsurface. Our results provide an ice sheet-wide first-order characterization of how ice-ocean processes modulate Greenland freshwater export, and are an important step towards accurate representation of Greenland freshwater in large-scale ocean models.</p>

scholarly journals Preclinical Characterization of Naturally Occurring Polyketide Cyclophilin Inhibitors from the Sanglifehrin Family

2011 ◽  
Vol 55 (5) ◽  
pp. 1975-1981 ◽  
Author(s):  
Matthew A. Gregory ◽  
Michael Bobardt ◽  
Susan Obeid ◽  
Udayan Chatterji ◽  
Nigel J. Coates ◽  
...  
Keyword(s):  
Large Scale ◽  
Scale Production ◽  
Subgenomic Replicon ◽  
Isomerase Activity ◽  
Lead Compounds ◽  
Naturally Occurring ◽  
Large Scale Production ◽  
Pharmacokinetic Properties ◽  
Biosynthetic Engineering

ABSTRACTCyclophilin inhibitors currently in clinical trials for hepatitis C virus (HCV) are all analogues of cyclosporine (CsA). Sanglifehrins are a group of naturally occurring cyclophilin binding polyketides that are structurally distinct from the cyclosporines and are produced by a microorganism amenable to biosynthetic engineering for lead optimization and large-scale production by fermentation. Preclinical characterization of the potential utility of this class of compounds for the treatment of HCV revealed that the natural sanglifehrins A to D are all more potent than CsA at disrupting formation of the NS5A-CypA, -CypB, and -CypD complexes and at inhibition of CypA, CypB, and CypD isomerase activity. In particular, sanglifehrin B (SfB) was 30- to 50-fold more potent at inhibiting the isomerase activity of all Cyps tested than CsA and was also shown to be a more potent inhibitor of the 1b subgenomic replicon (50% effective concentrations [EC50s] of 0.070 μM and 0.16 μM in Huh 5-2 and Huh 9-13 cells, respectively). Physicochemical and mouse pharmacokinetic analyses revealed low oral bioavailability (F< 4%) and low solubility (<25 μM), although the half-lives (t1/2) of SfA and SfB in mouse blood after intravenous (i.v.) dosing were long (t1/2> 5 h). These data demonstrate that naturally occurring sanglifehrins are suitable lead compounds for the development of novel analogues that are less immunosuppressive and that have improved metabolism and pharmacokinetic properties.

Seismic Reflection for Near-surface Characterization of Earthen Dams and Dikes: Upstream, Downstream

2015 ◽  
Author(s):  
Richard D. Miller ◽  
Richard D. Markiewicz ◽  
Julian Ivanov ◽  
Shelby Peterie ◽  
Jianghai Xia
Keyword(s):  
Seismic Reflection ◽  
Surface Characterization ◽  
Near Surface ◽  
Earthen Dams

Electrical Characterization of As-Processed Semiconductor Surfaces - Invited Paper

2016 ◽  
Vol 255 ◽  
pp. 299-303
Author(s):  
Jerzy Ruzyllo ◽  
Patrick J. Drummond
Keyword(s):  
Surface Characterization ◽  
Process Development ◽  
Electrical Characterization ◽  
Experimental Results ◽  
Surface Photovoltage ◽  
Semiconductor Surface ◽  
Semiconductor Surfaces ◽  
Near Surface

The paper is concerned with electrical characterization of as-processed semiconductor surfaces and near-surface regions for the purpose of process development and monitoring. The methods of electrical characterization based on Surface Photovoltage (SPV) and Photoconductance Decay (PCD) effects are discussed as being particularly conducive with the needs of as-processed semiconductor surface characterization and experimental results demonstrating merits of the proposed methodology are presented.

scholarly journals Rat thimet oligopeptidase: large-scale expression in Escherichia coli and characterization of the recombinant enzyme

1995 ◽  
Vol 309 (1) ◽  
pp. 203-207 ◽  
Author(s):  
N McKie ◽  
P M Dando ◽  
M A Brown ◽  
A J Barrett
Keyword(s):  
Escherichia Coli ◽  
Large Scale ◽  
Chemical Properties ◽  
Zinc Content ◽  
Recombinant Enzyme ◽  
Naturally Occurring ◽  
Thimet Oligopeptidase ◽  
Thiol Content

The coding sequence for rat testis thimet oligopeptidase (TOP) (EC 3.4.24.15) was placed under the control of the T7 polymerase/promoter system. Cultures of Escherichia coli transfected with the resulting plasmid expressed the enzyme as a soluble cytoplasmic protein. Medium-scale cultures allowed isolation of the enzyme in quantities of tens of milligrams. The availability of the recombinant enzyme permitted the determination of such chemical properties as epsilon 280 (48,960), zinc content (2 atom/molecule) and available thiol content (8-10/molecule) for TOP. The recombinant enzyme showed the catalytic activities previously reported for the naturally occurring enzyme, so that we can now conclude with confidence that these are all due to TOP and there is no need to postulate the existence of separate ‘Pz-peptidase’ or ‘endo-oligopeptidase A’ enzymes.

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