<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

SNU Management

The room-temperature reaction of [Os3(CO)12] with [PdCl(allyl)(NHC)], where NHC (N-heterocyclic carbene) = SIPr [N,N′-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene] or IPr [N,N′-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene], afforded Pd-Os mixed metal clusters with formulas of [PdnOs3(CO) 12(NHC)n] (n = 1-3). These are the first examples of Pd-Os heterometallic clusters containing NHC ligands, and they have all been structurally characterized. In all these clusters, the metal cores are raftlike, with carbonyl ligands bridging all the Os-Pd edges. © 2013 American Chemical Society.

World University root node

Organometallics

Palladium-osmium heterometallic clusters containing N-heterocyclic carbene ligands

An electrochemical study on biotin (vitamin B7), performed in aprotic solvents and at a platinum electrode, revealed that at approximately Ef0=-1.6 to -1.8 vs. (Fc/Fc+)/V (Ef0=formal reduction potential and Fc=ferrocene), biotin is reduced by one-electron to form its carboxylate anion and dihydrogen via a direct discharge of the carboxylic acid at the platinum surface. The electrochemical reduction process appeared to be chemically reversible on the time-frame of cyclic voltammetry (CV) (t ≤ s), but not over the extended period of controlled potential electrolysis (CPE) (t ≥ min) where the conversion of biotin into its carboxylate anion was found to be chemically irreversible. A strategy to functionalize biotin's carboxyl group was established by performing a bulk reductive electrolysis, and then reacting the electrochemically generated carboxylate anion with iodomethane to afford biotin methyl ester in excellent yield (91%). Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was successful in identifying several distinct and characteristic carbonyl absorbance peaks associated with the analogous forms of biotin available before electrolysis, after electrolysis, and after methylation. © 2013 Elsevier Ltd. All rights reserved.

Electrochimica Acta

The electrochemical reduction of biotin (vitamin B7) and conversion into its ester

Porphyromonas gingivalis is a Gram-negative oral anaerobe which is strongly associated with periodontal disease. Environmental changes in the gingival sulcus trigger the growth of P. gingivalis and a concurrent shift from periodontal health to disease. Bacteria adjust their physiology in response to environmental changes and gene regulation by two-component phospho-relay systems is one mechanism by which such adjustments are effected. In P. gingivalis RprY is an orphan response regulator and previously we showed that the RprY regulon included genes associated with oxidative stress and sodium metabolism. The goals of the present study were to identify environmental signals that induce rprY and clarify the role of the regulator in the stress response. In Escherichia coli an RprY-LacZ fusion protein was induced in sodium- depleted medium and a P. gingivalis rprY mutant was unable to grow in similar medium. By several approaches we established that sodium depletion induced up-regulation of genes involved in oxidative stress. In addition, we demonstrated that RprY interacted directly with the promoters of several molecular chaperones. Further, both genetic and transcription data suggest that the regulator acts as a repressor. We conclude that RprY is one of the regulators that controls stress responses in P. gingivalis, possibly by acting as a repressor since an rprY mutant showed a superstress reponse in sodium-depleted medium which we propose inhibited growth. © 2013 Krishnan, Duncan.

Fulltext

PLoS ONE

Role of Sodium in the RprY-Dependent Stress Response in Porphyromonas gingivalis

We report our progress towards a high performance solid-state ring laser gyro using a diode-pumped Nd-YAG crystal as the gain medium. We then discuss the possibility of including in this device a highly dispersive medium, which could serve for testing the recent proposal by Shariar and coworkers of a fast-light ring laser gyro. This discussion is supported in particular by the recent results obtained at Laboratoire Aimé Cotton with electromagnetically induced transparency in metastable helium © 2013 SPIE.

Proceedings of SPIE - The International Society for Optical Engineering

The solid-state ring laser gyro: Current and future trends

We investigate the dynamics of two-photon correlations generated by the interaction of a three-level atom in the Ξ, Λ or V configuration, with two classical external driving fields, under the rotating-wave approximation, in the presence of level decays. Using the example of a rubidium atom in each configuration, with field strengths validating the single-photon approximation, we compute measurement-based correlations, such as measurement induced disturbance (MID), quantum discord (QD), and quantum work deficit (WD), and compare the results with that from quantum entanglement (concurrence). Certain correlation properties observed are generic, model independent and consistent with known results, e.g.,MID is an upper bound on QD, QD and WD are monotonic, and the generic correlation behavior is strongly affected by the purity of the photon states. We observe that the qualitative hierarchy, monotonicity and steady-state behavior of the correlations can be controlled through the choice of parameters such as atomic decay constants and external driving field strengths. We point out how particular configurations are better suited to generating monotonic correlations in specific regimes and how the steady-state correlation behavior and hierarchy are affected by the population dynamics of the density matrix for different parameters. The possibility of using well studied quantum optical systems such as the three-level atom to generate, characterize and parametrically control mixed state quantum correlations establishes an important step in the direction of their implementation in quantum information tasks. © 2013 Elsevier Inc.

Annals of Physics

Controllable quantum correlations of two-photon states generated using classically driven three-level atoms

We show that by rotating the orthogonally polarized coupling and probe beams with respect to an applied magnetic field, one can manipulate the detuned EIT peaks and the central CPO peak in a tripod system of He*. © OSA 2013.

Optics InfoBase Conference Papers

Polarization dependent manipulation of optical properties in a tripod system of metastable helium

The reaction of 1-phenyl-2-lithio-3,4-dimethylphosphole with W(CO) 6 at -90 C followed by methyl triflate at room temperature gives the complex [(phosphol-2-yl)methoxycarbene]pentacarbonyltungsten (1). This complex reacts with sulfur to give the corresponding complex [methyl (phosphol-2-yl)thiocarboxylate]pentacarbonyltungsten (2), in which tungsten has migrated from the carbene to phosphorus. The reaction of 3 with alkynes at 90 C gives the corresponding phospholene-annelated cyclopentenones 5 without the need for a nickel catalyst. In one case, an intermediate vinylketene rearranges by an intramolecular Diels-Alder reaction to give the tricyclic compound 6. All of the products have been characterized by X-ray crystal structure analysis. © 2013 American Chemical Society.

Annelation of phosphole-substituted fischer carbene complexes by alkynes

The original reactivity of a phosphole-substituted Fischer carbene complex

We present an experimental and numerical study of the dynamics of a semiconductor laser subject to filtered optical feedbacks (FOFs) from two separate external cavities. Our results show that the inclusion of a second FOF introduces a rich control over the frequency of the dynamics. The period of frequency oscillations of the laser light is determined by the two time scales related to the feedback loops, and the frequency corresponding to this period is given by the average of the fundamental frequencies of the two cavities. The average frequency is dependent on the relative feedback from the cavities. Proper adjustment of the cavity lengths leads to the oscillations at a frequency which represents the average of the higher harmonics of one cavity and the fundamental frequency of the other cavity. The amplitudes of the frequency components in the single-FOF can be controlled by adding a second FOF, and in particular, the amplitude of the fundamental frequency is suppressed while the amplitude of the second harmonic becomes larger than that of the fundamental frequency. A cascade of period doubling bifurcations leads the dynamics to a chaotic state. © 1965-2012 IEEE.

IEEE Journal of Quantum Electronics

Semiconductor laser dynamics with two filtered optical feedbacks

The reaction of a terminal alkyne (RCCH) and 2-aminopyridine (R′C5NH3NH2) with the dinuclear species [Cp*IrCl2]2 afforded the cationic aminocarbene derivatives Cp*Ir(Cl)[ =C(CH2R)NHC5NH 3R′] via a hydroamination and a ligand substitution. The reaction pathway has been examined through computational studies. © 2013 American Chemical Society.