Diffusive behavior and structural characterization of a hard-sphere fluid through a narrow channel with roughened walls

2002 ◽  
Vol 80 (7) ◽  
pp. 723-731
Author(s):  
H Vahedi Tafreshi ◽  
G Benedek ◽  
P Zamankhan ◽  
P J Sarkomaa
Keyword(s):  
Hard Sphere ◽  
Particle Diameter ◽  
Narrow Channel ◽  
Contour Plot ◽  
Particle Diffusion ◽  
Static Structure Factor ◽  
Static Structure ◽  
Hard Sphere Fluid ◽  
High Concentrations

A molecular dynamics technique is devised to simulate the flow of a hard-sphere fluid between two parallel roughened walls separated by a 10 particle diameter distance. The structural state of the system in different solid-volume fractions is characterized by analyzing the static-structure factor contour plot. At solids concentrations below [Formula: see text] [Formula: see text] 0.3, the calculations have shown no remarkable signature of the presence of the roughened confining walls similar to the previous unbounded simulation results (wide channel). At high concentrations, walls manifest their presence by reducing the particle diffusion in the direction of velocity gradient. Due to the metastability of the assembly, further increase in the solid fraction, [Formula: see text] [Formula: see text] 0.6, may yield a crystalline phase wherein diffusion coefficients vanish locally. PACS Nos.: 51.20+d, 61.20-p, 66.10Cb

Spherical harmonic projections of the static structure factor of the dipolar hard sphere model: Theory vs simulations

2020 ◽  
Vol 152 (20) ◽  
pp. 204501 ◽  
Author(s):  
Luis F. Elizondo-Aguilera ◽  
Ernesto C. Cortés-Morales ◽  
Pablo F. Zubieta-Rico ◽  
Magdaleno Medina-Noyola ◽  
Ramón Castañeda-Priego ◽  
...  
Keyword(s):  
Model Theory ◽  
Structure Factor ◽  
Spherical Harmonic ◽  
Hard Sphere ◽  
Hard Sphere Model ◽  
Static Structure Factor ◽  
Sphere Model ◽  
Static Structure

Estimation of Interaction Parameter and Structure Factor of Specific Drug Delivering Fluorocarbon Nanosystems

2010 ◽  
Vol 9 ◽  
pp. 133-138
Author(s):  
S. Ravi ◽  
K. Arockia Jayalatha
Keyword(s):  
Structure Factor ◽  
Input Parameter ◽  
Particle Interaction ◽  
Particle Diameter ◽  
Pair Potential ◽  
Static Structure Factor ◽  
Theoretical Point ◽  
Specific Drug ◽  
Static Structure ◽  
Packing Factor

From the theoretical point of view, characterization of nano particle interaction depends much on the particle diameter , packing factor , the parameter of the Lennard-Jonnes (LJ) pair potential function  (r) and static structure factor S (Q). A novel method suggested in this paper has been tested on seven specific drug delivering fluorocarbons by estimating the strength of interaction /k of  (r) and S(Q) in terms of the elementary parameter . The importance of this paper is that, the input parameter viz., packing factor has been obtained from the experimental ultrasonic velocity of those seven systems. Calculations were extended for different temperatures involving four different equations of states to back up the application of the model. Though there is a lack of analytical results to compare, our predictions are encouraging.

STATIC STRUCTURE FACTOR OF HARD-SPHERE YUKAWA SYSTEMS

1996 ◽  
Vol 10 (30) ◽  
pp. 1507-1515 ◽  
Author(s):  
JOSÉ-PEDRO RINO ◽  
NELSON STUDART
Keyword(s):  
Distribution Function ◽  
Computer Simulations ◽  
Structure Factor ◽  
Hard Sphere ◽  
Particle Distribution ◽  
Bbgky Hierarchy ◽  
Static Structure Factor ◽  
Static Structure ◽  
Theory Of Liquids ◽  
Hierarchy Equations

We have applied the Singwi, Tosi, Land and Sjölander approximation for the two-particle distribution function in the BBGKY hierarchy equations to investigate the properties of the hard-sphere Yukawa systems. The static structure factor and the radial distribution function are evaluated and compared with other approximations of the theory of liquids and computer simulations.

scholarly journals Simultaneous multiplexed materials characterization using a high-precision hard X-ray micro-slit array

2015 ◽  
Vol 22 (3) ◽  
pp. 653-660 ◽  
Author(s):  
Fan Zhang ◽  
Andrew J. Allen ◽  
Lyle E. Levine ◽  
Derrick C. Mancini ◽  
Jan Ilavsky
Keyword(s):  
Colloidal Suspension ◽  
Diffusion Constant ◽  
Functional Materials ◽  
Heterogeneous Structure ◽  
Static Structure Factor ◽  
Static Structure ◽  
Experimental Conditions ◽  
X Ray ◽  
In Operando

The needs both for increased experimental throughput and forin operandocharacterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges across the whole of crystallography. A novel measurement scheme that allows multiplexed simultaneous measurements from multiple nearby sample volumes is presented. This new approach enables better measurement statistics or direct probing of heterogeneous structure, dynamics or elemental composition. To illustrate, the submicrometer precision that optical lithography provides has been exploited to create a multiplexed form of ultra-small-angle scattering based X-ray photon correlation spectroscopy (USAXS-XPCS) using micro-slit arrays fabricated by photolithography. Multiplexed USAXS-XPCS is applied to follow the equilibrium dynamics of a simple colloidal suspension. While the dependence of the relaxation time on momentum transfer, and its relationship with the diffusion constant and the static structure factor, follow previous findings, this measurements-in-parallel approach reduces the statistical uncertainties of this photon-starved technique to below those associated with the instrument resolution. More importantly, we note the potential of the multiplexed scheme to elucidate the response of different components of a heterogeneous sample underidenticalexperimental conditions insimultaneousmeasurements. In the context of the X-ray synchrotron community, this scheme is, in principle, applicable to all in-line synchrotron techniques. Indeed, it has the potential to open a new paradigm forin operandocharacterization of heterogeneous functional materials, a situation that will be even further enhanced by the ongoing development of multi-bend achromat storage ring designs as the next evolution of large-scale X-ray synchrotron facilities around the world.

scholarly journals Adsorption Studies on Magnetic Nanoparticles Functionalized with Silver to Remove Nitrates from Waters

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1757
Author(s):  
Yesica Vicente-Martínez ◽  
Manuel Caravaca ◽  
Antonio Soto-Meca ◽  
Miguel Ángel Martín-Pereira ◽  
María del Carmen García-Onsurbe
Keyword(s):  
Magnetic Nanoparticles ◽  
Nitrate Content ◽  
Adsorption Efficiency ◽  
Experimental Conditions ◽  
Dependent Behavior ◽  
Before And After ◽  
Naoh Solution ◽  
High Concentrations ◽  
Interference Studies

This paper presents a novel procedure for the treatment of contaminated water with high concentrations of nitrates, which are considered as one of the main causes of the eutrophication phenomena. For this purpose, magnetic nanoparticles functionalized with silver (Fe3O4@AgNPs) were synthesized and used as an adsorbent of nitrates. Experimental conditions, including the pH, adsorbent and adsorbate dose, temperature and contact time, were analyzed to obtain the highest adsorption efficiency for different concentration of nitrates in water. A maximum removal efficiency of 100% was reached for 2, 5, 10 and 50 mg/L of nitrate at pH = 5, room temperature, and 50, 100, 250 and 500 µL of Fe3O4@AgNPs, respectively. The characterization of the adsorbent, before and after adsorption, was performed by energy dispersive X-ray spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller analysis and Fourier-transform infrared spectroscopy. Nitrates can be desorbed, and the adsorbent can be reused using 500 µL of NaOH solution 0.01 M, remaining unchanged for the first three cycles, and exhibiting 90% adsorption efficiency after three regenerations. A deep study on equilibrium isotherms reveals a pH-dependent behavior, characterized by Langmuir and Freundlich models at pH = 5 and pH = 1, respectively. Thermodynamic studies were consistent with physicochemical adsorption for all experiments but showed a change from endothermic to exothermic behavior as the temperature increases. Interference studies of other ions commonly present in water were carried out, enabling this procedure as very selective for nitrate ions. In addition, the method was applied to real samples of seawater, showing its ability to eliminate the total nitrate content in eutrophized waters.

scholarly journals Halogenated Volatile Organic Compounds in Water Samples and Inorganic Elements Levels in Ores for Characterizing a High Anthropogenic Polluted Area in the Northern Latium Region (Italy)

2021 ◽  
Vol 18 (4) ◽  
pp. 1628
Author(s):  
Mario Vincenzo Russo ◽  
Ivan Notardonato ◽  
Alberto Rosada ◽  
Giuseppe Ianiri ◽  
Pasquale Avino
Keyword(s):  
Organic Compounds ◽  
Mean Value ◽  
Greenhouse Crops ◽  
River Waters ◽  
Liquid Liquid Extraction ◽  
Volatile Organic ◽  
High Concentrations ◽  
Very High ◽  
Inorganic Fraction

This paper shows a characterization of the organic and inorganic fraction of river waters (Tiber and Marta) and ores/soil samples collected in the Northern Latium region of Italy for evaluating the anthropogenic/natural source contribution to the environmental pollution of this area. For organic compounds, organochloride volatile compounds in Tiber and Marta rivers were analyzed by two different clean-up methods (i.e., liquid–liquid extraction and static headspace) followed by gas chromatography–electron capture detector (GC-ECD) analysis. The results show very high concentrations of bromoform (up to 1.82 and 3.2 µg L−1 in Tiber and Marta rivers, respectively), due to the presence of greenhouse crops, and of chloroform and tetrachloroethene, due to the presence of handicrafts installations. For the qualitative and quantitative assessment of the inorganic fraction, it is highlighted the use of a nuclear analytical method, instrumental neutron activation analysis, which allows having more information as possible from the sample without performing any chemical-physical pretreatment. The results have evidenced high levels of mercury (mean value 88.6 µg g−1), antimony (77.7 µg g−1), strontium (12,039 µg g−1) and zinc (103 µg g−1), whereas rare earth elements show levels similar to the literature data. Particular consideration is drawn for arsenic (414 µg g−1): the levels found in this paper (ranging between 1 and 5100 µg g−1) explain the high content of such element (as arsenates) in the aquifer, a big issue in this area.

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