Noncommutative geometry inspired entropic inflation

Recently Verlinde proposed that gravity can be described as an emergent phenomena arising from changes in the information associated with the positions of material bodies. By using noncommutative geometry as a way to describe the microscopic microstructure of quantum spacetime, we derive modified Friedmann equation in this setup and study the entropic force modifications to the inflationary dynamics of early universe.     

Surface properties of polypropylene/organoclay nanocomposites

Influence of nanoclay amount on surface properties of the nanocomposites was investigated using Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement, scanning electron microscopy (SEM) and transmission spectroscopy (TS). Polypropylene based nanocomposites containing various loads of nanoclay were prepared by melt compounding. X-ray diffraction (XRD) characterized the dispersion of nanoclay in polymer matrix. AFM and SEM studies have shown increase in surface roughness by raising the amount of nanoclay. Contact angle measurements of the resultant nanocomposites have also shown improvement in wettability related to disperse part of surface tension. POM images illustrated an increase in the number of spherulite simultaneously with a decrease in their size; this result was also supported by differential scanning calorimetry (DSC).     

Chemical vapor deposition synthesis of tunable unsubstituted polythiophene

Despite having exceptional electroactive properties, applications of unsubstituted polythiophene (PTh) have been limited due to its insolubility. To overcome this challenge, we have employed oxidative chemical vapor deposition (oCVD) as a unique liquid-free technique to enable the oxidative polymerization of PTh using thiophene as the starting monomer and vanadium oxytrichloride as an effective vaporizable oxidant initiator. Vibrational and phototelectron spectroscopy indicated the formation of unsubstituted polythiophene. Cyclic voltammetry revealed its electrochromic behavior in solution. Significantly, polymer conjugation length and electrical conductivity can be tuned by controlling oCVD process variables. Polymerization is found to be adsorption-limited, so by providing sufficient monomer and limiting the amount of initiator at the growth surface, PTh is believed to be formed through α-α thiophene linkages.     

Modeling action-interdependence in multiple criteria decision making

A problem of subset selection when actions are interdependent is formulated within a multiple criteria framework. More specifically, a novel definition and characterization of interdependence of actions applicable to Multiple Criteria Decision Making (MCDM) are presented. The effects of interdependence of actions on the modeling and resolution of a subset choice problem are shown, and the importance of taking interdependence of actions into account is discussed. Most of the discussion is generalized to independence and interdependence of sets of actions, which are then compared to the case of individual actions. A general approach to evaluate a combination of interdependent actions is proposed and the use of the multiple criteria structure to eliminate some difficulties in evaluating a set of interdependent actions is explained.     

Linearized and non‐linear acoustic/viscous splitting techniques for low Mach number flows

Computation of the acoustic disturbances generated by unsteady low‐speed flow fields including vortices and shear layers is considered. The equations governing the generation and propagation of acoustic fluctuations are derived from a two‐step acoustic/viscous splitting technique. An optimized high order dispersion–relation–preserving scheme is used for the solution of the acoustic field. The acoustic field generated by a corotating vortex pair is obtained using the above technique. The computed sound field is compared with the existing analytic solution. Results are in good agreement with the analytic solution except near the centre of the vortices where the acoustic pressure becomes singular. The governing equations for acoustic fluctuations are then linearized and solved for the same model problem. The difference between non‐linear and linearized solutions falls below the numerical error of the simulation. However, a considerable saving in CPU time usage is achieved in solving the linearized equations. The results indicate that the linearized acoustic/viscous splitting technique for the simulation of acoustic fluctuations generation and propagation by low Mach number flow fields seems to be very promising for three‐dimensional problems involving complex geometries. Copyright © 2003 John Wiley & Sons, Ltd.     

On the choice of the coupling parameter in boundary integral formulations of the exterior acoustic problem

Most commonly used boundary integral formulations of the exterior problem in time-harmonic acoustics, which are valid for all wave-numbers, involve a non-zero coupling parameter. In this paper we analyse the qualitative behaviour of the direct boundary integral formulation due to Burton and Miller. In particular we include a regularised formulation for the Neumann problem. By deriving the eigensystems of the operators we are able to obtain ′almost optimal′ values for the coupling parameter, as a function of the wave-number, so as to minimize the condition number of various formulations     

Establishing an Iranian medical laboratory standard based on ISO 15189

To strengthen clinical laboratories’ capabilities, the Reference Health Laboratory (RHL) of the Ministry of Health decided to compile a national professional laboratory standard to be followed by all medical laboratories in the country. Providing a national laboratory standard, as approved criteria for competency assessment, is also essential for establishment of a national accreditation system for medical laboratories. ISO 15189 addresses different processes and activities in a medical laboratory, but considering the local situation and limitations in the country it was not feasible to implement all the requirements of ISO 15189 at once in laboratories in different sectors and in different provinces of the country. For this reason, the RHL decided to define and publish the national standard, as minimum quality requirements that could be mandatory for all clinical laboratories throughout the country. After conducting a countrywide situation analysis, a national standard was composed by RHL expert committees and officially announced in September 2007. The main reference of this standard was ISO 15189:2007, although some important technical details were added to it from other credible references, such as WHO documents and CLSI guidelines. In this study, the Iranian national standard is compared to ISO 15189:2007 in terms of format and content in order to show how an international standard was localized for compiling a national standard.     

Surface characterization of polyethylene terephthalate/silica nanocomposites

Poly(ethylene terephthalate) (PET) based nanocomposites containing hydrophilic (i.e. Aerosil 200 or Aerosil TT 600) or hydrophobic (i.e. Aerosil R 972) nano-silica were prepared by melt compounding. Influence of nano-silica type on surface properties of the resultant nanocomposites was investigated by the use of Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), contact angle measurement (CAM), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). The possible interaction between nano-silica particles and PET functional groups at bulk and surface were elucidated by transmission FTIR and FTIR-ATR spectroscopy, respectively. AFM studies of the resultant nanocomposites showed increased surface roughness compared to pure PET. Contact angle measurements of the resultant PET composites demonstrated that the wettability of such composites depends on surface treatment of the particular nano-silica particles used. SEM images illustrated that hydrophilic nano-silica particles tended to migrate to the surface of the PET matrix.