Selective Hydrogenation of 1-Butene Rich Cuts: the Impact of the Intraparticle Diffusion Limitations on the Selectivity

2003 ◽  
Vol 26 (7) ◽  
pp. 783-789
Author(s):  
S.P. Bressa ◽  
J.A. Alves ◽  
O.M. Martínez ◽  
G.F. Barreto
Keyword(s):  
Selective Hydrogenation ◽  
Intraparticle Diffusion ◽  
Diffusion Limitations ◽  
The Impact

scholarly journals Stability enhancement in a mAb and Fab coformulation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hongyu Zhang ◽  
Paul A. Dalby
Keyword(s):  
Individual Component ◽  
Degradation Kinetics ◽  
Therapeutic Proteins ◽  
Fab Fragment ◽  
Diffusion Limitations ◽  
Therapeutic Monoclonal Antibody ◽  
Dead End ◽  
Sites Of Action ◽  
Stability Enhancement ◽  
The Impact

AbstractMultiple therapeutic proteins can be combined into a single dose for synergistic targeting to multiple sites of action. Such proteins would be mixed in dose-specific ratios to provide the correct potency for each component, and yet the formulations must also preserve their activity and keep degradation to a minimum. Mixing different therapeutic proteins could adversely affect their stability, and reduce the shelf life of each individual component, making the control of such products very challenging. In this study, a therapeutic monoclonal antibody and a related Fab fragment, were combined to investigate the impact of coformulation on their degradation kinetics. Under mildly destabilizing conditions, these proteins were found to protect each other from degradation. The protective effect appeared to originate from the interaction of Fab and IgG1 in small soluble oligomers, or through the rapid coalescence of pre-existing monomeric IgG1 nuclei into a dead-end aggregate, rather than through macromolecular crowding or diffusion-limitations.

scholarly journals On the Use of Dual Cell Density Monoliths

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1075
Author(s):  
Ivan Cornejo ◽  
Gonzalo Garreton ◽  
Robert E. Hayes
Keyword(s):  
Pressure Drop ◽  
Cell Density ◽  
Conversion Efficiency ◽  
Flow Distribution ◽  
Apparent Permeability ◽  
Diffusion Limitations ◽  
Relevant Evidence ◽  
Automotive Catalytic Converters ◽  
Flow Maldistribution ◽  
The Impact

Monolith-type substrates are extensively used in automotive catalytic converters and have gained popularity in several other industrial processes. Despite their advantages over traditional unstructured catalysts, such as large surface area and low pressure drop, novel monolith configurations have not been investigated in depth. In this paper, we use a detailed computational model at the reactor scale, which considers entrance length, turbulence dissipation and internal diffusion limitations, to investigate the impact of using a dual cell substrate on conversion efficiency, pressure drop, and flow distribution. The substrate is divided into two concentric regions, one at its core and one at its periphery, and a different cell density is given to each part. According to the results, a difference of 40% in apparent permeability is sufficient to lead to a large flow maldistribution, which impacts conversion efficiency and pressure drop. The two mentioned variables show a positive or negative correlation depending on what part of the substrate—core or ring—has the highest permeability. This and other results contribute relevant evidence for further monolith optimization.

scholarly journals Tailoring the framework composition of carbon nitride to improve the catalytic efficiency of the stabilised palladium atoms

2017 ◽  
Vol 5 (31) ◽  
pp. 16393-16403 ◽  
Author(s):  
E. Vorobyeva ◽  
Z. Chen ◽  
S. Mitchell ◽  
R. K. Leary ◽  
P. Midgley ◽  
...  
Keyword(s):  
Selective Hydrogenation ◽  
Carbon Nitride ◽  
Catalytic Efficiency ◽  
The Impact ◽  
Framework Composition

The C/N ratio of the carbon nitride lattice is tailored by doping with carbon to assess the impact on the stabilisation of palladium atoms and their catalytic efficiency in the selective hydrogenation of 2-methyl-3-butyn-2-ol.

Experimental design of diffusion and desorption of contaminant in heterogeneous media

2011 ◽  
Vol 64 (4) ◽  
pp. 988-998
Author(s):  
Guannan Jiang ◽  
Michelle Crimi ◽  
Kathleen Fowler ◽  
Xiaojing Fu
Keyword(s):  
Experimental Design ◽  
Heterogeneous Media ◽  
Diffusion Processes ◽  
Experimental System ◽  
Intraparticle Diffusion ◽  
Transport Processes ◽  
Low Permeability ◽  
Site Assessment ◽  
Treatment Volume ◽  
The Impact

Storage of contaminants in low permeability media (LPM) presents a great challenge for prediction of remediation effectiveness and efficiency. The reason lies in the contaminants' complex behaviors within heterogeneous media. Both interparticle and intraparticle diffusion contribute to the difficulty of precise site assessment. Sorption of contaminants – especially within LPM – may sequester the contaminants from active treatment, while desorption over a long period of time leads to contaminant release from storage and consequent re-contamination. Research has been conducted toward better understanding of contaminant diffusion and sorption/desorption processes to better predict contaminant response to site treatment. However, most of the research has been carried out within homogeneous media, while real scenarios in environmental problems feature media whose permeability and other characteristics vary significantly over the treatment volume. Further, few efforts have combined the interparticle/intraparticle diffusion and sorption/desorption processes together. This research aims at a feasible experimental design of diffusion and desorption of contaminant in heterogeneous media to address the gaps in previous research. A 2-D experimental system was designed to evaluate interparticle/intraparticle diffusion processes of trichloroethylene (TCE) in heterogeneous media. The 2-D system was modified to include organic matter in media for simulation of sorption/desorption processes. Results of the research will improve the understanding of how these different transport processes act together within heterogeneous media. Results will also allow for the evaluation of the impact of contaminant mass transport from within low permeability media at a potential treatment site and can support the development of mathematical tools/models combining interparticle/intraparticle and sorption/desorption processes. Such a model will promote more accurate site assessment and provide more confidence in the choice of an effective, economically optimized remediation strategy.

scholarly journals Beyond the effectiveness factor: Multi-step reactions with intraparticle diffusion limitations

2020 ◽  
Vol 380 ◽  
pp. 122507 ◽  
Author(s):  
Aaron M. Lattanzi ◽  
M. Brennan Pecha ◽  
Vivek S. Bharadwaj ◽  
Peter N. Ciesielski
Keyword(s):  
Intraparticle Diffusion ◽  
Effectiveness Factor ◽  
Diffusion Limitations

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

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