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Ogale S.B.,CSIR - National Chemical Laboratory | Ogale S.B.,Indian Institute of Science
Advanced Materials | Year: 2010

Over the past decade intensive research efforts have been carried out by researchers around the globe on exploring the effects of dilute doping of magnetic impurities on the physical properties of functional non-magnetic metal oxides such as TiO 2 and ZnO. This effort is aimed at inducing spin functionality (magnetism, spin polarization) and thereby novel magnetotransport and magneto-optic effects in such oxides. After an early excitement and in spite of some very promising results reported in the literature, this field of diluted magnetic semiconducting oxides (DMSO) has continued to be dogged by concerns regarding uniformity of dopant incorporation, the possibilities of secondary ferromagnetic phases, and contamination issues. The rather sensitive dependence of magnetism of the DMSO systems on growth methods and conditions has led to interesting questions regarding the specific role played by defects in the attendant phenomena. Indeed, it has also led to the rapid re-emergence of the field of defect ferromagnetism. Many theoretical studies have contributed to the analysis of diverse experimental observations in this field and in some cases to the predictions of new systems and scenarios. In this review an attempt is made to capture the scope and spirit of this effort highlighting the successes, concerns, and questions. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Kulkarni A.A.,CSIR - National Chemical Laboratory
Beilstein Journal of Organic Chemistry | Year: 2014

This review highlights the state of the art in the field of continuous flow nitration with miniaturized devices. Although nitration has been one of the oldest and most important unit reactions, the advent of miniaturized devices has paved the way for new opportunities to reconsider the conventional approach for exothermic and selectivity sensitive nitration reactions. Four different approaches to flow nitration with microreactors are presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed. © 2014 Kulkarni; licensee Beilstein-Institut. License and terms: see end of document. Source


Sen S.S.,CSIR - National Chemical Laboratory
Angewandte Chemie - International Edition | Year: 2014

Mission accomplished: More than 100 years after first attempts at isolating a stable silanone, this task has finally been completed with the isolation of a metallosilanone complex (see Scheme). The elusive bare Si-O bond was made accessible by utilizing the coordination sphere of an electron-rich chromium fragment in combination with a sterically demanding saturated N-heterocyclic carbene (NHC) to protect the reactive site. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Narlikar L.,CSIR - National Chemical Laboratory
Nucleic acids research | Year: 2014

An important question in biology is how different promoter-architectures contribute to the diversity in regulation of transcription initiation. A step forward has been the production of genome-wide maps of transcription start sites (TSSs) using high-throughput sequencing. However, the subsequent step of characterizing promoters and their functions is still largely done on the basis of previously established promoter-elements like the TATA-box in eukaryotes or the -10 box in bacteria. Unfortunately, a majority of promoters and their activities cannot be explained by these few elements. Traditional motif discovery methods that identify novel elements also fail here, because TSS neighborhoods are often highly heterogeneous containing no overrepresented motif. We present a new, organism-independent method that explicitly models this heterogeneity while unraveling different promoter-architectures. For example, in five bacteria, we detect the presence of a pyrimidine preceding the TSS under very specific circumstances. In tuberculosis, we show for the first time that the spacing between the bacterial 10-motif and TSS is utilized by the pathogen for dynamic gene-regulation. In eukaryotes, we identify several new elements that are important for development. Identified promoter-architectures show differential patterns of evolution, chromatin structure and TSS spread, suggesting distinct regulatory functions. This work highlights the importance of characterizing heterogeneity within high-throughput genomic data rather than analyzing average patterns of nucleotide composition. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research. Source


Late D.J.,CSIR - National Chemical Laboratory
ACS Applied Materials and Interfaces | Year: 2015

Atomically thin two-dimensional (2D) sheets of black phosphorus have attracted much attention due to their potential for future nanoelectronic and photonics device applications. Present investigations deal with the temperature dependent phonon shifts in a few-layer black phosphorus nanosheet sample prepared using micromechanical exfoliation on a 300 nm SiO2/Si substrate. The temperature dependent Raman spectroscopy experiments were carried out on a few-layer black phosphorus sample, which depicts softening of Ag 1, B2g, and Ag 2 modes as temperature increases from 77 to 673 K. The calculated temperature coefficients for Ag 1, B2g, and Ag 2 modes of the few-layer black phosphorus nanosheet sample were observed to be -0.01, -0.013, and -0.014 cm-1 K-1, respectively. The temperature dependent softening modes of black phosphorus results were explained on the basis of a double resonance process which is more active in an atomically thin sample. This process can also be fundamentally pertinent in other promising and emerging 2D ultrathin layer and heterostructured materials. (Graph Presented). © 2015 American Chemical Society. Source

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