Microstructure and growth of ZnTe films

The microstructure and growth of ZnTe films deposited onto glass and freshly cleaved NaCl substrates are carefully studied by a TEM. Effect of different stimulator on the grain growth is also described.     

Design and Analysis of Ultra-Miniaturized Meandering Photonic Crystals Delay Lines

In this paper, we study the characteristics of a novel miniaturized optical delay line, which delays light in a meandering photonic crystal waveguide, and describe the design steps. We show how lattice parameters and refractive index difference of the photonic crystal affect the bandgap width and suggest a criterion to select these parameters. Next, we focus on the parallel waveguide channels in photonic crystal, and analyze the impact of the channel length and the interchannel spacing on crosstalk. We suggest a method for mitering the sharp corners in meandering lines which reduces the undesired reflections by 8 dB. Considering all these guidelines, we examine the propagation of light in the proposed delay line through calculating time-delay and insertion loss. To achieve longer delays in a small device area, we concentrate on coupled cavities in photonic crystals and propose an approximate method for calculating the group velocity of light in the coupled defects. We show how by replacing waveguide channels of a meandering delay line with coupled defects we achieve time-delays more than 9 ps within a device size around 27 m, which corresponds to a miniaturization factor of 100.     

Analysis of photo-excited thin superconducting films for optoelectronic device applications

This paper introduces a steady state photoresponse analysis in superconducting thin films. A model is developed for investigating the capability of superconductors for potential optoelectronic applications. First, we consider the thermodynamical variation under the application of continuous optical radiation in superconducting state. Then, the photo-induced changes in electrical parameters are evaluated from thermodynamical variations using the electrodynamics based on the BCS theory. All variations are considered as a function of optical characteristics along with the material properties. The numerical simulation gives us the optimum range of applied optical frequency and absorbed radiation intensity required for sensitive control of superconducting properties for optoelectronic and microwave applications.     

On the compositional dependence of the optical gap and structural properties of amorphous In x Se1−x thin films

The optical gap of the amorphous In _x Se_1–x thin film has been observed to decrease with increasing content of indium in the film (x). An attempt is made to interpret the compositional dependence of the optical gap in amorphous In _x Se_1–x thin film in an alloy-like approach. It has been found that introduction of higher concentrations of indium imparts greater stability to the structure of the indium selenium alloy. From the study of the radial distribution function (RDF) by X-rays it is observed that there is a correlation between the coordination number and the optical gap of indium selenide thin films.     

Cytosine Arabinoside Release from Polymeric Matrices

Cytosine arabinoside (Ara-C) has been used in the treatment of acute myeloid leukemia. However, rapid deamination reduces its effectiveness. Polymeric matrices containing ara-C were prepared in polyether polyurethane copolymer to form a protective, supply of ara-C. Release studies from these devices showed linear relationships between Q, the amount release per unit area, versus the square root of time. Burst effects were predominant at higher loading doses. The diffusivity values indicated that enough drug could pass through the polymer for the combination to have potential application as implants in cancer therapy.     

Choked flow and importance of Mach I in freeze-drying process design

Occasionally the freeze drying cycle conditions are developed on a small scale dryer that result in a water vapor flux during primary drying that the full-scale equipment cannot handle, resulting in loss of the ability to control chamber pressure. A primary cause of loss of pressure control is a phenomenon commonly described as “choked flow”, where the required mass transfer through the duct connecting the drying and condenser chamber cannot be maintained at the control pressure. Water vapor flow rate increases as the condenser pressure decreases, but it can continue to do so only until the velocity of water vapor reaches speed of sound (i.e., Mach I) at the duct exit. The flow is then said to be choked, and any further increase in water vapor flow rate results in an increase in chamber pressure (i.e., loss in chamber pressure control). Sublimation tests were carried out in Lyostar II freeze-dryer (SP Industries, NY) to predict the occurrence of choked flow. A capacitance manometer was installed in the “condenser chamber” and differential pressure (P_c?P_cd) was measured as a function of sublimation rate (P_c=chamber pressure and P_cd=condenser pressure). Water vapor flow rate was measured by Tunable Diode Laser Absorption Spectroscopy (TDLAS) methodology, with a check by gravimetric data. Flow of water vapor in the duct connecting chamber and the condenser was modeled using computational fluid dynamics software (Fluent 6.3). The critical pressure ratio (K?=P_c/P_cd) has been identified as an important variable that determines the onset of choked flow during primary drying. This ratio can be calculated given the mass flux. For our freeze-dryer, K* greater than 2.5 (for P_c<150 mTorr) resulted in choked flow. The gas velocity indeed reaches Mach I limit at the duct exit under the choked flow conditions, as modeled by Fluent. Using the differential pressure measurements, the throat connecting the chamber and the condenser can be used as an “in process” mass flow meter to measure sublimation rate under non-choked flow conditions during primary drying without interrupting the process. Also, TDLAS is a useful tool for determination of sublimation rate even at very high mass flux.     

Philosophical Dimensions of Information and Ethics in the Internet of Things (IoT) Technology

This article discusses the various dimensions of philosophy of information for the Internet of Things (IoT) technology. The aspects of attention, subjectivity, objectivity, happiness, key ethical concerns, and the need for algorithmic transparency and accountability in autonomous IoT applications that are necessary to build an IoT belief system have been highlighted here. The interplay of smart devices, smart services, and humans has been depicted to highlight trust permeability in human and IoT interfaces.     

Photoconductivity in CuInSe2 films

CulnSe₂ films with different Cu/In ratios (0.4–1.2) were deposited on glass substrates by three source evaporation techniques. The films were polycrystalline in nature with partially depleted grains. Photoconductivity in the films was measured in the temperature range 170–370 K. The data at low temperatures (T < 300 K) were analyzed by using the grain boundary trapping model with monovalent trapping states. The intercrystalline barrier height in dark varied within 0.13 and 0.08 eV with the variation of Cu/In within 0.4 and 1.18. The variation of the barrier height with the intensity of the incident photons in the range 10–75 mW / cm² was analyzed to understand the carrier detrapping effect in the films under various illumination levels.     

An object-based coding scheme for frontal surface of defective fluted ingot

A novel image-based defect identification and coding technique has been proposed for fluted ingots, which are used for the production of locomotive wheels. The edge density map has been used for defect identification and an object-based coding approach has been applied for the storage of defective ingots. The complete scheme has been implemented in one of the integrated steel plants of India.