Epitaxial growth of CdTe on Si through perovskite oxide buffers

For the first time, nanometer-thin perovskite oxide buffers have been used to accommodate the lattice mismatch between CdTe epitaxial layers and Si substrates. The resulting CdTe is single crystal with quality comparable to that grown by the more mature technology using micron-thick ZnTe or CdTe buffers. This shows that the use of nanometer-thin perovskite oxide buffers is a promising approach for the epitaxial growth of II–VI compounds on Si.     

Synthesis and characterization of tanninsulfonic acid doped polyaniline–metal oxide nanocomposites

Composites of conducting polymers and metal oxides have a potential role in electronic devices because of their enhanced physical and electronic properties. An in situ synthesis of metal oxide nanocomposites of polyaniline (PANI) and tanninsulfonic acid doped PANI was carried out at ?10°C with two different ratios of aniline to sodium persulfate (oxidant) and the simultaneous incorporation of TiO₂, Al₂O₃, and ZnO nanopowders. The products were characterized by X‐ray diffraction (XRD), thermal analysis, spectroscopy, and electrical conductivity measurements. XRD and thermogravimetric analysis confirmed the presence of the metal oxide in the final product, whereas the spectroscopic characterization revealed interactions among the tannin, metal oxides, and PANI. The electrical properties were determined by four‐point‐probe bulk conductivity measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Ionic Silicon Protects Oxidative Damage and Promotes Skeletal Muscle Cell Regeneration

Volumetric muscle loss injuries overwhelm the endogenous regenerative capacity of skeletal muscle, and the associated oxidative damage can delay regeneration and prolong recovery. This study aimed to investigate the effect of silicon-ions on C2C12 skeletal muscle cells under normal and excessive oxidative stress conditions to gain insights into its role on myogenesis during the early stages of muscle regeneration. In vitro studies indicated that 0.1 mM Si-ions into cell culture media significantly increased cell viability, proliferation, migration, and myotube formation compared to control. Additionally, MyoG, MyoD, Neurturin, and GABA expression were significantly increased with addition of 0.1, 0.5, and 1.0 mM of Si-ion for 1 and 5 days of C2C12 myoblast differentiation. Furthermore, 0.1–2.0 mM Si-ions attenuated the toxic effects of H₂O₂ within 24 h resulting in increased cell viability and differentiation. Addition of 1.0 mM of Si-ions significantly aid cell recovery and protected from the toxic effect of 0.4 mM H₂O₂ on cell migration. These results suggest that ionic silicon may have a potential effect in unfavorable situations where reactive oxygen species is predominant affecting cell viability, proliferation, migration, and differentiation. Furthermore, this study provides a guide for designing Si-containing biomaterials with desirable Si-ion release for skeletal muscle regeneration.     

Insight of electrical behavior in ferroelectric‐semiconductor polymer nanocomposite films of PVDF/ZnSe and PVDF/Cu:ZnSe

Nanocomposite thin films (NCTF) of low‐dimensional ZnSe and copper doped ZnSe integrated poly(vinylidene fluoride) (PVDF) polymer were developed via simple solution casting method. Herein, ZnSe and Cu:ZnSe nanoparticles were synthesized through the chemical reduction technique. The obtained low‐dimensional nanoparticles and NCTFs were characterized by XRD, SEM/EDS, TEM, and FTIR analysis. Room temperature dielectric and ferroelectric characteristics of PVDF/ZnSe flexible NCTF exhibited superior dielectric and ferroelectric behavior with a high coercive field of 15.6 V. Whereas, the dielectric and ferroelectric characteristics were greatly diminished in the PVDF/Cu:ZnSe flexible NCTF was due to the conducting behavior of copper ions at the interface of the polymer network. These results indicated that the PVDF/ZnSe flexible NCTF will be a potential candidate for advanced electrical applications and device fabrication. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44983.     

Mass transfer correlation for phenol biodegradation in a fluidized bed bioreactor

Experiments have been carried out in a draft tube fluidized bed bioreactor to study biodegradation of synthetic wastewater containing phenol. The microorganism employed in the study Psuedomonas putida has been immobilized on solid support particles. Studies have been carried out at different feed concentrations of phenol, air flow rates and feed flow rates. The mass transfer coefficient for phenol transfer from bulk phase to the surface of the biofilm on the solid particle has been estimated from observed experimental data using the conservation equations. The mass transfer coefficient was found to be in the range of 0.0726 x 10(-5) to 0.2012 x 10(-5) m s(-1). It was found to increase with increase in feed concentration, air flow rate and feed flow rate. A dimensionless correlation has been developed for the mass transfer coefficient in terms of Sherwood, Reynolds and Schmidt numbers, and the same has been compared with correlations available in literature.     

Contactless measurement of minority carrier lifetime in silicon ingots and bricks

Measuring the bulk lifetime of unpassivated blocks and ingots is of great interest to the solar cell industry. The eddy‐current photoconductance method is a common choice for such measurements, employing the quasi‐steady‐state (QSS) mode for lower lifetime samples, and the transient photoconductance decay (PCD) mode for higher lifetime samples. Due to the high surface recombination velocity in unpassivated bulk samples, the lifetime measured with this method consists of components of recombination at both the surface and in the bulk. In order to determine the bulk lifetime from the measurement data, simulations of both transient and QSS mode measurements were conducted. Copyright © 2010 John Wiley & Sons, Ltd.     

Fatigue Growth Analysis of Pre Induced Surface Defects Using Piezoelectric Wafer Based Impedance Method and Digital Image Correlation System

Defects in real mechanical, industrial and aerospace structures frequently have complex shapes. Most real structures are typically prone to multiple fatigue cracks and their propagation can be monitored by observing changes in the structural stiffness resulting from strength reduction as a function of the number of loading cycles. In addition, strain variations on the structural surface can be captured using digital equipments. The present work monitors two specimens (AISI 4340 steel) with electrode sparked hemispherical defects on their surfaces. Multiple-cracks emanating from these defects, under fatigue cyclic loading were monitored using piezoelectric wafer based electromechanical impedance (EMI) technique, and digital image correlation (DIC) system. EMI technique uses signature comparison of healthy and damaged state of the structure to depict the occurrence of crack and its growth. Images of DIC system captures initial sightings of surface hair-line cracks from the corners of machined defects and their propagation till merging. Thus, a signature analysis based technique such as EMI and image processing technology such as DIC were found to complement each other to expedite the prediction of early crack and their appearance on the surface.     

Handwritten text separation from annotated machine printed documents using Markov Random Fields

The convenience of search, both on the personal computer hard disk as well as on the web, is still limited mainly to machine printed text documents and images because of the poor accuracy of handwriting recognizers. The focus of research in this paper is the segmentation of handwritten text and machine printed text from annotated documents sometimes referred to as the task of “ink separation” to advance the state-of-art in realizing search of hand-annotated documents. We propose a method which contains two main steps—patch level separation and pixel level separation. In the patch level separation step, the entire document is modeled as a Markov Random Field (MRF). Three different classes (machine printed text, handwritten text and overlapped text) are initially identified using G-means based classification followed by a MRF based relabeling procedure. A MRF based classification approach is then used to separate overlapped text into machine printed text and handwritten text using pixel level features forming the second step of the method. Experimental results on a set of machine-printed documents which have been annotated by multiple writers in an office/collaborative environment show that our method is robust and provides good text separation performance.     

Three-Dimensional Electromechanical Impedance Model. I: Formulation of Directional Sum Impedance

Piezoceramic transducers (PZTs) are extensively used in vibration and noise control, and damage detection of various engineering structures. In the last decade, its application has been extended to include their interactions with the host structure in electromechanical impedance models. The interaction between the host structure and PZT is governed by both the extensional and longitudinal vibrations of the transducer. However, the interaction models developed in the last decade consider only the one-dimension or two-dimension extensional actuations, ignoring the longitudinal actuations. This study examines the three-dimensional (3D) interaction of a transducer with the host structure, considering both the extensional and the longitudinal actuations of the transducer. It does not impose any restriction on the shape, size, and electrical properties of the PZT and thus contains additional features over the existing PZT-structure interaction models. This paper is Part I of a two-part paper, which presents a new “directional sum” numerical–analytical admittance formulation with experimental verification. Part II of this paper will elaborate on the damage analysis and characterization of PZT properties for the new 3D model.