scholarly journals Evasive plankton: Size‐independent particle capture by ascidians

2021 ◽  
Author(s):  
Yuval Jacobi ◽  
Noa Shenkar ◽  
J. Evan Ward ◽  
Maria Rosa ◽  
Guy Z. Ramon ◽  
...  
Keyword(s):  
Particle Capture ◽  
Independent Particle

Теория гетерогенного катализа. Теория хемосорбции

2021 ◽  
Author(s):  
Василий Садовников
Keyword(s):  
Heterogeneous Catalysis ◽  
Potential Energy ◽  
Publishing House ◽  
Cell Number ◽  
Oil Refining ◽  
Lateral Interaction ◽  
Reaction Products ◽  
Crystal Face ◽  
Independent Particle ◽  
The Face

This monograph is a continuation of the monograph by V.V. Sadovnikov. Lateral interaction. Moscow 2006. Publishing house "Anta-Eco", 2006. ISBN 5-9730-0017-6. In this work, the foundations of the theory of heterogeneous catalysis and the theory of chemisorption are more easily formulated. The book consists of two parts, closely related to each other. These are the theoretical foundations of heterogeneous catalysis and chemisorption. In the theory of heterogeneous catalysis, an experiment is described in detail, which must be carried out in order to isolate the stages of a catalytic reaction, to find the stoichiometry of each of the stages. This experiment is based on the need to obtain the exact value of the specific surface area of the catalyst, the number of centers at which the reaction proceeds, and the output curves of each of the reaction products. The procedures for obtaining this data are described in detail. Equations are proposed and solved that allow calculating the kinetic parameters of the nonequilibrium stage and the thermodynamic parameters of the equilibrium stage. The description of the quantitative theory of chemisorption is based on the description of the motion of an atom along a crystal face. The axioms on which this mathematics should be based are formulated, the mathematical apparatus of the theory is written and the most detailed instructions on how to use it are presented. The first axiom: an atom, moving along the surface, is present only in places with minima of potential energy. The second axiom: the face of an atom is divided into cells, and the position of the atom on the surface of the face is set by one parameter: the cell number. The third axiom: the atom interacts with the surrounding material bodies only at the points of minimum potential energy. The fourth axiom: the solution of the equations is a map of the arrangement of atoms on the surface. The fifth axiom: quantitative equations are based on the concept of a statistically independent particle. The formation energies of these particles and their concentration are calculated by the developed program. The program based on these axioms allows you to simulate and calculate the interaction energies of atoms on any crystal face. The monograph is intended for students, post-graduate students and researchers studying work and working in petrochemistry and oil refining.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

The feeding behaviour of Florometra serratissima (Echinodermata: Crinoidea)

1981 ◽  
Vol 59 (1) ◽  
pp. 11-18 ◽  
Author(s):  
M. Byrne ◽  
A. R. Fontaine
Keyword(s):  
Feeding Behaviour ◽  
Vancouver Island ◽  
Particle Capture ◽  
Particle Collection ◽  
Slack Water ◽  
Feeding Activities ◽  
Characteristic Behaviour

The feeding behaviour of the comatulid crinoid Florometra serratissima (A. H. Clark) was studied at two sites around Vancouver Island. It appears to inhabit areas where currents are slight. The arms are held in a cone posture during slack water but in mild currents they orient to form a partial arm fan.Tube foot behaviour was observed in situ and in aquaria. The podia arise in groups of three, each podium of the triplet exhibiting a characteristic behaviour related to its role in feeding. The primary podia are typically held extended; they initiate the mechanism of particle capture, secrete mucous threads, and are sensory. The secondary podia, attached to the lappet for much of their length, scoop to collect particles and perhaps mucous threads. The tertiary podia manipulate material in the food grooves. Lappet action appears to aid particle collection through scraping along the primary podia.These feeding activities are compared with those reported for Antedon bifida (Pennant) and other crinoids.

Comment on Dr. Gilmour's views on feeding by hemichordates and lophophorates

1982 ◽  
Vol 60 (12) ◽  
pp. 3466-3468 ◽  
Author(s):  
Richard R. Strathmann
Keyword(s):  
Particle Capture ◽  
Ciliary Motion

Observations on motion of captured particles, films of ciliary motion during particle capture, and physical theories of the motion of particles and water contradict substantial parts of Dr. Gilmour's accounts of ciliary feeding by hemichordates and lophophorates. (T. H. J. Gilmour. 1982. Feeding in tornaria larvae and the development of gill slits in enteropneust hemichordates. Can. J. Zool. 60. This issue.)

First principles study of the structural, electronic and optical properties of crystalline o-phenanthroline

2016 ◽  
Vol 30 (14) ◽  
pp. 1650077 ◽  
Author(s):  
Hajar Nejatipour ◽  
Mehrdad Dadsetani
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Binding Energies ◽  
Many Body ◽  
Generalized Gradient ◽  
Generalized Gradient Approximation ◽  
Independent Particle ◽  
Excitonic Effects ◽  
Comprehensive Study

In a comprehensive study, structural properties, electronic structure and optical response of crystalline o-phenanthroline were investigated. Our results show that in generalized gradient approximation (GGA) approximation, o-phenanthroline is a direct bandgap semiconductor of 2.60 eV. In the framework of many-body approach, by solving the Bethe–Salpeter equation (BSE), dielectric properties of crystalline o-phenanthroline were studied and compared with phenanthrene. Highly anisotropic components of the imaginary part of the macroscopic dielectric function in o-phenanthroline show four main excitonic features in the bandgap region. In comparison to phenanthrene, these excitons occur at lower energies. Due to smaller bond lengths originated from the polarity nature of bonds in presence of nitrogen atoms, denser packing, and therefore, a weaker screening effect, exciton binding energies in o-phenanthroline were found to be larger than those in phenanthrene. Our results showed that in comparison to the independent-particle picture, excitonic effects highly redistribute the oscillator strength.

Potential barrier effect and discrete structure o between 40 and 120 Å in the Rb I absorption spectrum

1975 ◽  
Vol 344 (1637) ◽  
pp. 303-309 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Maximum ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Particle Model ◽  
Discrete Structure ◽  
Model Calculations ◽  
Hartree Fock ◽  
Independent Particle ◽  
Independent Particle Model

Investigation of the Rb I absorption spectrum between 40 and 120 Å has revealed a broad absorption maximum in the 3d photoionization continuum, as well as discrete features associated with the excitation of a 3d-subshell electron. The discrete structure is identified, Hartree-Fock calculations of the transition energies are given and the absorption maximum is discussed in relation to similar spectra and to recent random phase approximation with exchange (r.p.a.e.) and independent particle model calculations.

Sign in / Sign up

Export Citation Format

Share Document