Chromatography in pore networks II — The role of structure and adsorption in the band broadening

1991 ◽  
Vol 32 (7-8) ◽  
pp. 345-349 ◽  
Author(s):  
J. S. Andrade ◽  
K. Rajagopal ◽  
C. McGreavy
Keyword(s):  
Band Broadening ◽  
Pore Networks

Variational Models of Pore Networks in Ionomer Membranes: The Role of Electrostatics

2013 ◽  
Vol 50 (2) ◽  
pp. 161-173 ◽  
Author(s):  
K. Promislow ◽  
J. Jones ◽  
Z. Xu ◽  
N. Gavish ◽  
A. Christlieb
Keyword(s):  
Variational Models ◽  
Pore Networks ◽  
Ionomer Membranes

scholarly journals Ion fractionation in young sea ice from Kongsfjorden, Svalbard

2011 ◽  
Vol 52 (57) ◽  
pp. 301-310 ◽  
Author(s):  
Sönke Maus ◽  
Susann Müller ◽  
Juliane Büttner ◽  
Sabina Brütsch ◽  
Thomas Huthwelker ◽  
...  
Keyword(s):  
Sea Ice ◽  
Thermal History ◽  
Sea Water ◽  
Arctic Sea Ice ◽  
Salt Transport ◽  
Differential Diffusion ◽  
Pore Networks ◽  
Arctic Sea ◽  
History Of

AbstractThe fractionation of major sea-water ions, or deviation in their relative concentrations from Standard Mean Ocean Water ratios, has been frequently observed in sea ice. It is generally thought to be associated with precipitation of solid salts at certain eutectic temperatures. the variability found in bulk sea-ice samples indicates that the fractionation of ions depends on the often unknown thermal history of sea ice, which affects the structure of pore networks and fate of solid salts within them. Here we investigate the distribution of ions in Arctic sea ice that is a few weeks old with a reconstructible thermal history. We separate the centrifugable (interconnected) and entrapped (likely disconnected) contributions to the ice salinity and determine their ion fractionation signatures. the results indicate that differential diffusion of ions, rather than eutectic precipitation of cryohydrates, has led to significant ion fractionation. the finding emphasizes the role of coupled diffusive–convective salt transport through complex pore networks in shaping the biogeochemistry of sea ice.

PHASE STABILITY OF BCC TRANSITION METALS: ROLE OF d-ELECTRONS

2000 ◽  
Vol 14 (06) ◽  
pp. 635-642
Author(s):  
ABDULLAH M. HUSSEIN ◽  
S. M. MUJIBUR RAHMAN
Keyword(s):  
Transition Metals ◽  
Phase Stability ◽  
Magnetic Moments ◽  
Structural Phase ◽  
Electronic States ◽  
Magnetic Contribution ◽  
Band Broadening ◽  
Structural Part ◽  
Density Of Electronic States

The role of d-electrons in the structural phase stability of bcc transition metals viz. V, Fe, Cr and Mn are investigated. The underlying theory expresses the relevant structural part of the free energy in terms of the repulsion of the d-electron muffin-tin orbitals assigned to atomic sites and the attractive contribution arising from the band broadening effects of the d-bands in the total energy. The magnetic contribution arising from the population of magnetic moments in the systems is also included in the theory. The d-electronic contribution to entropy is written in terms of the density-of-electronic states at the respective Fermi level. The phase stability of the bcc transition metals is explained in terms of the population of atoms on the local and extended sites. It is observed that the d-electron energetics can precisely and correctly predict the crystal structure of the bcc transition metals.

Nanocomposite Hydride LaNi5/A- and Mg2Ni/A-Type Materials (A=C, Cu, Pd)

2009 ◽  
Vol 610-613 ◽  
pp. 472-479 ◽  
Author(s):  
Mieczyslaw Jurczyk ◽  
Marek Nowak ◽  
Izabela Okonska ◽  
Lewlaw Smardz ◽  
A. Szajek
Keyword(s):  
Electrode Materials ◽  
Nanocrystalline Structure ◽  
Band Broadening ◽  
Mechanically Alloyed ◽  
Alloy Particles ◽  
Strong Deformation ◽  
Band Spectra ◽  
Valence Bands ◽  
Mechanical Coating

In this work, we have synthesized LaNi5/A and Mg2Ni/A (A = graphite, copper or palladium) nanocomposites. The A elements were distributed on the surface of ball milled alloy particles homogenously and role of these particles is to catalyze the dissociation of molecular hydrogen on the surface of studied alloy. Mechanical coating with graphite or palladium effectively reduced the degradation rate of the studied electrode materials. Results showed a significant broadening of the valence bands of studied nanocomposites compared to those obtained by theoretical band calculations. The reasons responsible for the band broadening of the nanocrystalline LaNi5- and Mg2Ni-type alloys are probably associated with a strong deformation of the nanocrystals in the mechanically alloyed (MA) samples. Normally the interior of the nanocrystal is constrained and the distances between atoms located at the grain boundaries expanded. The valence band spectra of the MA samples could be also broadened due to an additional disorder introduced during formation of the nanocrystalline structure.

A directed percolation model for the permeability of young sea ice

2021 ◽  
Author(s):  
Sönke Maus
Keyword(s):  
Sea Ice ◽  
Pore Space ◽  
Thermal Fluctuations ◽  
Percolation Model ◽  
First Year ◽  
Directed Percolation ◽  
Pore Networks ◽  
Melt Pond ◽  
Starting Point

<p>The permeability of sea ice is an important property with regard to the role of sea ice in the earth system. It controls fluid flow within sea ice, and thus affects processes like desalination and melt pond drainage. It also impacts the role of sea ice in hosting sea ice algae and organisms, and the uptake and release of nutrients and pollutants from Arctic surface waters. However, as sea ice permeability is difficult to measure in the field, observations are sparse and vary, even for similar porosity, over orders of magnitude. This range is related to the evolution of the sea ice pore space during aging from young ice to thick first year ice. In young ice, the pore network is dominated by primary pores constrained by brine layers and the near-interface microstructure. In older sea ice, the ongoing desalination and thermal fluctuations have created wider secondary brine channels, implying a several orders of magnitude higher permeability. It is a challenge to understand and model these changes in pore space and permeability. Here a directed percolation model for the permeability of young sea ice is proposed. The model describes the dependence of sea ice permeability and electrical conductivity on brine porosity, and its critical behaviour and percolation transition due to necking of pores, and related disconnection of pore networks. Its parameters are based on 3D X-ray micro-tomographic imaging of young sea ice and direct numerical simulation of its transport properties, that strongly support the application of directed percolation theory to young sea ice, with a threshold porosity (impermeable ice) of 2 to 3 percent. Combined to an approach to predict the crystal structure at the ice-ocean interface, the model also the growth-velocity dependence and evolution of permeability near the ice-ocean interface. As the model is strictly valid for growing and cooling sea ice, without present of wider secondary brine channels, it is mostly relevant for sea ice desalination processes during winter. Modelling permeability of older and summer ice (and melt pond drainage) will require more observations of the pore space evolution in warming sea ice, for which the present results can be considered as a starting point.</p>

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

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