TBHP-Mediated Intermolecular Radical Coupling and Intramolecular Cyclization Cascade: Access to Furo[2,3-b]quinoxalines and Their Photophysical Study

A cascade one-pot strategy to construct 31 examples of furo-fused quinoxalines in up to 88% yields has been devised from readily accessible β-ketothioamides and quinoxalin-2-ones in open flask at room temperature under TBHP mediated conditions. Mechanistic studies revealed that the overall reactivity relies on the seamless integration of intermolecular radical coupling and intramolecular cyclization via desulfhydration of C=S bond cleavage. Generation of H₂S as the only by-product makes this process highly attractive. Furthermore, the photophysical behavior of the furo-fused quinoxalines has also been studied.     

Study of Fourier transform near infrared (FT‐NIR) spectra of ghee (anhydrous milk fat)

Ghee is chemically highly complex in nature. The authentication and characterisation of edible fats and oils by routine chemical methods are highly laborious and time‐consuming. Fourier transform near infrared (FT‐NIR) spectroscopy has emerged as the predominant analytical tool in the study of edible fats/oils. In order to assign absorption bands in the infrared (IR) spectrum, spectra of cow and buffalo ghee samples were acquired in the NIR region (10 000–4000 cm^?1). In the FT‐NIR spectrum, a total of nine peaks were obtained for cow and buffalo ghee, with almost equal intensity of absorption. The intensity of absorbance was higher for cow ghee compared to buffalo ghee.     

Analysis of variance in spectroscopic imaging data from human tissues

The analysis of cell types and disease using Fourier transform infrared (FT-IR) spectroscopic imaging is promising. The approach lacks an appreciation of the limits of performance for the technology, however, which limits both researcher efforts in improving the approach and acceptance by practitioners. One factor limiting performance is the variance in data arising from biological diversity, measurement noise or from other sources. Here we identify the sources of variation by first employing a high throughout sampling platform of tissue microarrays (TMAs) to record a sufficiently large and diverse set data. Next, a comprehensive set of analysis of variance (ANOVA) models is employed to analyze the data. Estimating the portions of explained variation, we quantify the primary sources of variation, find the most discriminating spectral metrics, and recognize the aspects of the technology to improve. The study provides a framework for the development of protocols for clinical translation and provides guidelines to design statistically valid studies in the spectroscopic analysis of tissue.     

A simple and efficient XFEM approach for 3-D cracks simulations

In this work, a simple and efficient XFEM approach has been presented to solve 3-D crack problems in linear elastic materials. In XFEM, displacement approximation is enriched by additional functions using the concept of partition of unity. In the proposed approach, a crack front is divided into a number of piecewise curve segments to avoid an iterative solution. A nearest point on the crack front from an arbitrary (Gauss) point is obtained for each crack segment. In crack front elements, the level set functions are approximated by higher order shape functions which assure the accurate modeling of the crack front. The values of stress intensity factors are obtained from XFEM solution by domain based interaction integral approach. Many benchmark crack problems are solved by the proposed XFEM approach. A convergence study has been conducted for few test problems. The results obtained by proposed XFEM approach are compared with the analytical/reference solutions.     

Simulation and performance analysis of duobinary 40 Gbps optical link

This paper presents a system model to simulate and evaluate the performance of duobinary RZ (DB-RZ) and duobinary NRZ (DB-NRZ) modulation format in a 40?Gbps optical communication link. The design has been optimized to estimate the electrical and optical filter parameters for optimum performance under dispersion and self-phase modulation induced impairments. The presented model has been operated under various OSNR conditions to investigate the limitations of GVD and SPM on the BER-equivalent Q-factor for DB-NRZ and DB-RZ encoded optical data. The analysis reports the superiority of DB-NRZ over DB-RZ at higher OSNR. However, for a typical OSNR value a crossover optical filter bandwidth has been observed beyond which DB-RZ outperforms DB-NRZ.     

Effect of growth temperature on structural, electrical and optical properties of dual ion beam sputtered ZnO thin films

ZnO epitaxial thin films were grown on p-type Si(100) substrates by dual ion beam sputtering deposition system. The crystalline quality, surface morphology, optical and electrical properties of as-deposited ZnO thin films at different growth temperatures were studied. Substrate temperature was varied from 100 to 600 °C at constant oxygen percentage O₂/(O₂ + Ar) % of 66.67 % in a mixed gas of Ar and O₂ with constant chamber pressure of 2.75 × 10^?4 mBar. X-Ray diffraction analyses revealed that all the films had (002) preferred orientation. The minimum value of stress was reported to be ?0.32 × 10¹⁰ dyne/cm² from ZnO film grown at 200 °C. Photoluminescence measurements demonstrated sharp near-band-edge emission (NBE) was observed at ~375 nm along with deep level emission (DLE) in the visible spectral range at room temperature. The DLE Peak was found to have decrement as ZnO growth temperature was increased from 200 to 600 °C. The minimum FWHM of the NBE peak of 16.76 nm was achieved at 600 °C growth temperature. X-Ray photoelectron spectroscopy study revealed presence of oxygen interstitials and vacancies point defects in ZnO film grown at 400 °C. The ZnO thin film was found to be highly resistive when grown at 100 °C. The ZnO films were found to be n-type conducting with decreasing resistivity on increasing substrate temperature from 200 to 500 °C and again increased for film grown at 600 °C. Based on these studies a correlation between native point defects, optical and electrical properties has been established.     

Free Vibration of Thermally Pre/Post-Buckled Circular Thin Plates Embedded with Shape Memory Alloy Fibers

Axisymmetric deformations of a uniformly heated pre-buckled and post-buckled thin circular plate reinforced with shape memory alloy (SMA) fibers placed in the radial direction only are studied. Effects of von Kármán's nonlinearities are incorporated in the problem formulation. The matrix is assumed to be linear thermoelastic and the thermo-mechanical response of the SMA is modeled by one-dimensional constitutive relation. By assuming that plate's deflections can be additively decomposed into three parts, namely radial displacements of a pre-buckled plate, radial and lateral displacements during post-buckling deformations, and infinitesimal radial and lateral displacements during vibration of a post-buckled plate, boundary-value problems for determining these displacements for plate edges either simply supported or clamped have been formulated. The coupled nonlinear differential equations have been numerically solved by the shooting method that has been verified by good agreement between the presently computed results with those available in the literature. The dependence of the first three frequencies upon the temperature rise, for both pre-buckled and post-buckled plates, has been delineated. Characteristic curves relating the frequency with the temperature rise for different values of the volume fraction and the pre-strain in the SMA fibers are exhibited. It is found that reinforcement of an aluminum plate with SMA fibers changes plate's natural frequencies and enhances its resistance to buckling due to temperature rise.     

Increasing the accuracy of ECG based biometric analysis by data modelling

Here an effort is made to use human electrocardiogram as a tool of biometric analysis for authentication. The proposed method is based on first accurate extraction of characteristic features from each ECG and then design of a suitable classification methodology to comment on the authenticity. As the feature matrix is a huge one, Principal Component Analysis (PCA) is applied to avoid handling of large amount of data. Next, the reduced features from PCA are fitted into a quadratic polynomial model by the method of least square. Then the fitted values for the allowed set of data is obtained and the range over which they vary, provides the signature matrix of a person. Finally the classification is done by a comparison based on nearest neighbor method. The method is tested on ECG of 20 individuals taken from PTB database. This method has accuracy more than 95% with the best fit modeling which becomes only 80% without data modeling proving the importance of best fit modeling of data before classification. This accuracy is comparable with conventional biometric techniques; moreover, ECG biometric can be used with other authentication scheme, with ECG providing liveliness proof.     

Stereospecific formation of a ternary complex of (S)-α,β-fluoromethylene-dATP with DNA pol β

The influence of water: crystallization of (R/S)-α,β-CHF-dATP with the preorganized pol β-DNA complex shows that (S)-α,β-CHF-dATP is preferentially bound to the active site with the C=F fluorine proximal to a structural water bound to Asp276.     

Toward multiple catheters detection in fluoroscopic image guided interventions

Catheters are routinely inserted via vessels to cavities of the heart during fluoroscopic image guided interventions for electrophysiology (EP) procedures such as ablation. During such interventions, the catheter undergoes nonrigid deformation due to physician interaction, patient's breathing, and cardiac motions. EP clinical applications can benefit from fast and accurate automatic catheter tracking in the fluoroscopic images. The typical low quality in fluoroscopic images and the presence of other medical instruments in the scene make the automatic detection and tracking of catheters in clinical environments very challenging. Toward the development of such an application, a robust and efficient method for detecting and tracking the catheter sheath is developed. The proposed approach exploits the clinical setup knowledge to constrain the search space while boosting both tracking speed and accuracy, and is based on a computationally efficient framework to trace the sheath and simultaneously detect one or multiple catheter tips. The algorithm is based on a modification of the fast marching weighted distance computation that efficiently calculates, on the fly, important geodesic properties in relevant regions of the image. This is followed by a cascade classifier for detecting the catheter tips. The proposed technique is validated on 1107 fluoroscopic images acquired on multiple patients across four different clinics, achieving multiple catheter tracking at a rate of 10 images/s with a very low false positive rate of 1.06.