Asymmetric Effective Medium Approximation for Describing the Optical Characteristics of Randomly Inhomogeneous Media with Discrete Inclusions.

2020 ◽  
pp. 70-74
Author(s):  
Leon A. Apresyan ◽  
Tatyana V. Vlasova

The symmetric Bruggeman approximation, also known as the Effective Medium Approximation (EMA), is widely used in applications including the description of light scattering on inhomogeneous structures containing discrete inclusions. However, in the latter case, the natural asymmetry of the fillers topology, where discrete inclusions are mostly surrounded by the material of a simply connected matrix, is not taken into account. In this paper, two versions of asymmetric EMA are proposed for the case of a statistically isotropic medium containing discrete inclusions based on the difference in the structure of the fields inside and outside the inclusions. One of them does not differ too much from the usual EMA and leads to the same percolation threshold. For the second, the threshold value differs from the usual one even in the case of spherical particles. Expressions are given for the corresponding percolation thresholds in the model of randomly oriented elliptical particles. The proposed approximations are compared with the standard Maxwell Garnett and Bruggeman approximations for the case of silver particles in a dielectric matrix.

PIERS Online ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 365-368 ◽  
Author(s):  
D. M. Dolgushin ◽  
Anton P. Anzulevich ◽  
V. D. Buchelnikov ◽  
I. V. Bychkov ◽  
Dmitri V. Louzguine-Luzgin

2019 ◽  
Author(s):  
Αντόνιο Τζιουλιάνι

In this thesis, we reported advances in internal reflection techniques applied to the study of interfaces between a hard solid (glass substrate) and various soft material. Such developments might be valuable to the soft matter community as the techniques to study such interfacial processes are scarce. We present the principle and implementation of a novel in situ near wall dynamic light scattering velocimetry on a commercial rheometer. The method was tested on a variety of materials where different boundary conditions were observed, from stick to plug flow behavior. Furthermore we investigate the effect of multiple scattering on EW-DLS measurements. The localized scattering and the point of entrance detection of the EW geometry yield a sizable single scattering component that made it possible to recover quasi single scattering dynamics in strongly turbid media. Moreover studies under shear reveal strong temporal decoupling of the near wall single scattering dynamics and useful DWS like bulk shear rate information so that both the near wall velocimetry and DWS like velocimetry can be performed in the same experiment. We looked into the application and validity of effective medium models for turbid media in internal reflection variable angle spectroscopic ellipsometry (VASE). The proper description of the clear-turbid interface is not fully established. The reflectivity between a transparent substrate and a turbid medium is of interest as it could be used to characterize the turbid medium and provide a way to estimate size, refractive index and composition. Here we report on internal VASE to characterize turbid medium using an effective medium approximation. In particular we show the value of the wavelength dependence for determining the scattering losses. The merit of effective medium approximation based models is evaluated. We investigate the dynamics and pH induced swelling kinetics of high Mw polyelectrolyte brushes (PEB) after they have undergone strong degrafting. The results presented are preliminary. Measurements of internal dynamics of PEB’s are not intensely pursued in literature, due to lack of experimental techniques. Internal reflection VASE was used to determine wet thicknesses and measure its pH time response.


Author(s):  
Jan Abel Olsen

Chapter 19 starts by distinguishing between the two contrasting perspectives that an economic evaluation would take: the healthcare sector perspective versus the societal perspective. The former is considered a ‘narrow analysis’ which includes only the costs accruing within the healthcare sector, while the latter represents a ‘broad analysis’ that accounts for all resource implications in all sectors of the economy. After an investigation into various types of costs, a ‘limited societal perspective’ is suggested to be more appropriate than either of the two ‘extreme perspectives’. The chapter continues with a discussion of the cost per quality-adjusted life year (QALY) threshold and explains the difference between a demand side- versus a supply-side approach to determining a threshold value for a QALY.


1996 ◽  
Vol 150 ◽  
pp. 409-413
Author(s):  
Patrick P. Combet ◽  
Philippe L. Lamy

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.


2013 ◽  
Vol 760-762 ◽  
pp. 105-109 ◽  
Author(s):  
Jian Bin Liu ◽  
Hai Li ◽  
Ying Xin Zeng ◽  
Jia Wen Weng ◽  
Chu Ping Yang

An experimental apparatus for the analysis of biological cells light scattering in liquid suspensions has been presented. Characterization is based on the scattering of a monochromatic laser beam by particles [which can be inorganic, organic, or biological (such as animal cells and bacteria)] and on the strong relation between the light-scattering pattern and the morphology and refractive index of the particles. In order to study light scattering in biological cells close to the actual situation, we focus on non-spherical particles in the cell-culture medium. Finally, we demonstrate the light scattering results of bovine kidney cells suspended in the cell-culture medium, and compares then with the simulated results.


2010 ◽  
pp. NA-NA
Author(s):  
T. F. G. Muller ◽  
D. Knoesen ◽  
C. J. Arendse ◽  
S. Halindintwali ◽  
G. F. Malgas ◽  
...  

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