Indian Institute of Technology Ropar

About: Indian Institute of Technology Ropar is a education organization based out in Ropar, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 1014 authors who have published 2878 publications receiving 35715 citations.

Selective synthesis of Cu–Cu2O/C and CuO–Cu2O/C catalysts for Pd-free C–C, C–N coupling and oxidation reactions

Abstract: In this study, the preparation of economical Cu-based catalysts for Pd-free coupling and oxidation reactions was demonstrated. For the preparation of the Cu-based catalyst, first, a Cu-BTC MOF was prepared under ambient conditions. The Cu-BTC MOF was then carbonized in N2 to obtain Cu–Cu2O-supported carbon materials. Moreover, the Cu–Cu2O-supported carbon material was subjected to heating in O2 to obtain the CuO–Cu2O-supported carbon material. Formation of Cu-BTC-MOF, Cu–Cu2O, and CuO–Cu2O was confirmed via powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The amount and types of carbon present in the catalyst were confirmed using thermogravimetric analysis and Raman spectroscopy, respectively. The textural properties of the materials were determined using N2-sorption measurement. The morphology, porosity, and elemental composition were confirmed via the scanning and transmission electron microscopy images. The Cu–Cu2O-supported carbon material successfully catalyzed the Sonogashira cross-coupling (C–C cross-coupling reaction), Ullmann amination (C–N coupling reaction), and A3 coupling (decarboxylative C–C and C–N coupling) reactions; moreover, the CuO–Cu2O-supported carbon material successfully oxidized diphenylmethane in O2 at 1 atm. The catalysts were found to be stable and recyclable. Heterogeneity of the reaction was confirmed via the CS2 poisoning and hot-filtration tests. The presence of the optimum amount and the suitable oxidation state of Cu in the stable nanoporous carbon matrix having graphitic conducting nature were responsible for the excellent activity and recyclability. The results demonstrate that the applications of these Cu-based catalysts can be extended to several catalytic reactions that are known to be catalyzed using Pd and other costly metals.

Boronic acid based dynamic click chemistry: recent advances and emergent applications

Abstract: Recently, reversible click reactions have found numerous applications in chemical biology, supramolecular chemistry, and biomedical applications. Boronic acid (BA)-mediated cis-diol conjugation is one of the best-studied reactions among them. An excellent understanding of the chemical properties and biocompatibility of BA-based compounds has inspired the exploration of novel chemistries using boron to fuel emergent sciences. This topical review focuses on the recent progress of iminoboronate and salicylhydroxamic-boronate constituted reversible click chemistries in the past decade. We highlight the mechanism of reversible kinetics and its applications in chemical biology, medicinal chemistry, biomedical devices, and material chemistry. This article also emphasizes the fundamental reactivity of these two conjugate chemistries with assorted nucleophiles at variable pHs, which is of utmost importance to any stimuli-responsive biological and material chemistry explorations.

A Novel Distribution-Level Phasor Estimation Algorithm Using Empirical Wavelet Transform

Abstract: Distribution-level signals are often contaminated with harmonics and noise, along with dynamic conditions like frequency deviations. This paper proposes an empirical wavelet transform (EWT) based M-class distribution-level phasor estimation technique under such polluted and dynamic conditions. The capability of the EWT of extracting different frequency components present in the signal makes it suitable for distribution-level phasor estimation. However, the empirical wavelet filters are designed on the basis of the Fourier spectrum of the signal, which, inturn suffers from a spectral leakage problem at off-nominal frequencies. To avoid the errors arising due to spectral leakage, a sample value adjustment based prefiltering technique is employed. The effectiveness of the proposed estimator is demonstrated on various simulated signals, field-data, and real-time signals obtained from the hardware implementation setup. The proposed algorithm is found to be least affected by the presence of dc components, harmonics, and noise. The use of a fixed window size and fixed sampling frequency makes it suitable for synchronization with GPS clocks. The proposed scheme is also able to provide an accurate harmonic phasor estimation.

A novel feature descriptor for image retrieval by combining modified color histogram and diagonally symmetric co-occurrence texture pattern

Abstract: In this paper, we have proposed a novel feature descriptors combining color and texture information collectively. In our proposed color descriptor component, the inter-channel relationship between Hue (H) and Saturation (S) channels in the HSV color space has been explored which was not done earlier. We have quantized the H channel into a number of bins and performed the voting with saturation values and vice versa by following a principle similar to that of the HOG descriptor, where orientation of the gradient is quantized into a certain number of bins and voting is done with gradient magnitude. This helps us to study the nature of variation of saturation with variation in Hue and nature of variation of Hue with the variation in saturation. The texture component of our descriptor considers the co-occurrence relationship between the pixels symmetric about both the diagonals of a 3 × 3 window. Our work is inspired from the work done by Dubey et al. (IEEE Signal Process Lett 22(9):1215–1219, [2015]). These two components, viz. color and texture information individually perform better than existing texture and color descriptors. Moreover, when concatenated the proposed descriptors provide a significant improvement over existing descriptors for content base color image retrieval. The proposed descriptor has been tested for image retrieval on five databases, including texture image databases—MIT-VisTex database and Salzburg texture database and natural scene databases Corel 1K, Corel 5K and Corel 10K. The precision and recall values experimented on these databases are compared with some state-of-art local patterns. The proposed method provided satisfactory results from the experiments.