Optical characterization of organic material bromoindium phthalocyanine thin films grown by electron beam evaporation

This paper presents the optical properties of organic material bromoindium phthalocyanine (BrInPc) thin films grown by electron beam evaporation technique. The paper describes the optical characteristics of BrInPc thin films, which have been determined using spectrophotometric measurements of the absorbance, transmittance and reflectance at normal incident of light in the spectral range 300–1,100 nm. The optical band gap energy and type of the electronic transition have been determined by analysis of spectral behavior of absorption coefficient, which reveals the probability of both direct and indirect transitions. Other optical constants, such as refractive index, extinction coefficient, complex dielectric constant and optical conductivity of thin films have been evaluated. Moreover, the width of band tails of localized states (Urbach energy), steepness parameter and width of the defect states have been determined by studying the absorption coefficient spectra just below the fundamental absorption edge.     

Effects of Alfvenic Poloidal Flow and External Vertical Field on Plasma Position in IR-T1 Tokamak

We analyzed dynamic equilibrium properties of a large aspect ratio and low Beta tokamaks, in particular deriving a modified relation for the Shafranov shift in the presence of poloidal flow and external vertical field, and demonstrate it experimentally on the IR-T1 tokamak. Poloidal flow can produce modifications in the equilibrium properties. By increasing Alfvenic Mach number from zero, flow produce outward force, and plasma shifted in outward direction. If the poloidal Alfvenic Mach number equal to one, singularity will observe in the solution of generalized Grad–Shafranov equation. Also inversion of Shafranov shift in the transition of flow speed between sub-Alfvenic to super-Alfvenic speeds can be observed due to inward force produced by flow.     

Design and implementation of fluidic micro-pulleys for flow control on centrifugal microfluidic platforms

Microfluidic discs have been employed in a variety of applications for chemical analyses and biological diagnostics. These platforms offer a sophisticated fluidic toolbox, necessary to perform processes that involve sample preparation, purification, analysis, and detection. However, one of the weaknesses of such systems is the uni-directional movement of fluid from the disc centre to its periphery due to the uni-directionality of the propelling centrifugal force. Here we demonstrate a mechanism for fluid movement from the periphery of a hydrophobic disc towards its centre that does not rely on the energy supplied by any peripheral equipment. This method utilizes a ventless fluidic network that connects a column of working fluid to a sample fluid. As the working fluid is pushed by the centrifugal force to move towards the periphery of the disc, the sample fluid is pulled up towards the centre of the disc analogous to a physical pulley where two weights are connected by a rope passed through a block. The ventless network is analogous to the rope in the pulley. As the working fluid descends, it creates a negative pressure that pulls the sample fluid up. The sample and working fluids do not come into direct contact, and it allows the freedom to select a working fluid with physical properties markedly different from those of the sample. This article provides a demonstration of the “micro-pulley” on a disc, discusses underlying physical phenomena, provides design guidelines for fabrication of micro-pulleys on discs, and outlines a vision for future micro-pulley applications.     

Comparative Measurements of the Asymmetry Factor in Tokamaks Using the Magnetic Probes,Poloidal and Toroidal Flux Loops

Measurement of the Asymmetry factor (Shafranov parameter) is essential in tokamak plasma experiments. The purpose of this paper is comparing of the magnetic probes, poloidal flux loops, and diamagnetic loops techniques in determination of the Asymmetry factor in tokamaks. For this reason, array of magnetic probes, flux loops, and diamagnetic loop with its compensation coil, were designed, constructed, and installed on outer surface of the IR-T1 tokamak chamber, and then the Asymmetry factor and poloidal beta measured. Moreover, a few approximate values of the internal inductance for the different plasma current density profiles are also calculated. Experimental results compared.     

Simultaneous coloration and functional finishing of cotton fabric using Ag/ZnO nanocomposite

In this study, colored cotton fabric with special functions, including self‐cleaning, anti‐bacterial, and ultraviolet (UV) blocking were prepared by applying zinc oxide as a photocatalyst and using silver nanoparticles as both a novel class of colorant for coloration and an agent capable of modifying the zinc oxide nanoparticles. The homogenous distribution of Ag/ZnO nanocomposite on the fibre surface was confirmed by field emission scanning electron microscopy (FE‐SEM), Energy‐dispersive X‐ray spectroscopy (EDS) and X‐ray mapping. X‐ray diffraction patterns showed the presence of the nanocomposite on the treated cotton fabric. The results indicated that adding silver nanoparticles to zinc oxide led to better self‐cleaning properties, even the photocatalytic activity of ZnO had no negative effect on fabric colour. Moreover, this process imparted proper anti‐bacterial properties and UV‐blocking activity to cotton fabrics.     

On the mechanical behavior of a wide tunable capacitive MEMS resonator for low frequency energy harvesting applications

Microsystem Technologies - We present a method for tuning the resonance frequency of a comb resonator using a combination of mechanically softening and hardening springs in order to achieve a high...