Conformational study on dipeptides containing phenylalanine: A DFT approach

DFT calculations has been done applying 6-31G^* basis set on a series of dipeptides where the N-terminus position is fixed with phenylalanine and the C-terminus is varied with eight different amino acids. Different geometrical parameters (bond angle, bond length, geometry around -carbon atom) are thoroughly investigated to study the effect of amino acid sequence on dipeptide. Dihedral angle data analysis shows the deviation of amide plane from planarity, which is due to the combined effect of the steric hindrance of –R group and hydrogen bonding. The λ_max value for phenylalanine has been calculated, which shows good agreement with the experimental value. A rigid potential energy scan is performed on phenylalanine by rotating –CH₂Ph, –COOH and –NH₂ groups separately to get some idea about the conformational stability.     

Synthesis,physico-chemical and antimicrobial studies on acetylferrocenyl hydrazone derivatives of dichlorobis(cyclopentadienyl)hafnium(IV)

The reactions of Cp₂>HfCl₂> with hydrazones (LH) derived from acetylferrocene and aromatic acid hydrazides (benzoic, 2-chlorobenzoic, 3-nitrobenzoic and 4-toluic) in various stoichiometric ratios have been studied and the complexes of the types [Cp₂>Hf(L)Cl] and [CpHf(L)₃>] were obtained. Tentative structural conclusions are drawn for the reaction products based upon elemental analyses, electrical conductance, magnetic moment and spectral data (u.v.–vis, i.r., ¹>H-n.m.r. and ¹³>C-n.m.r.). Studies were conducted to assess the growth-inhibiting potential of the complexes synthesized, and the ligands, against various fungal and bacterial strains.     

Locally Restorable Routing of Highly Variable Traffic

Two-phase routing, where traffic is first distributed to intermediate nodes before being routed to the final destination, has been recently proposed for handling widely fluctuating traffic without the need to adapt network routing to changing traffic. Preconfiguring the network in a traffic independent manner using two-phase routing simplifies network operation considerably. In this paper, we extend this routing scheme by providing resiliency against link failures through fast restoration along link backup detours. We view this as important progress towards adding carrier-class reliability to the robustness of the scheme so as to facilitate its future deployment in Internet Service Provider (ISP) networks. On the theoretical side, the main contribution of the paper is the development of linear programming based and fast combinatorial algorithms for two-phase routing with link restoration so as to minimize the maximum utilization of any link in the network, or equivalently, maximize the throughput. The algorithms developed are fully polynomial time approximation schemes (FPTAS)-for any given isin > 0, an FPTAS guarantees a solution that is within a (1 + isin)-factor of the optimum and runs in time polynomial in the input size and 1/isin. To the best of our knowledge, this is the first work in the literature that considers making the scheme resilient to link failures through preprovisioned fast restoration mechanisms. We evaluate the performance of link restoration (in terms of throughput) and compare it with that of unprotected routing. For our experiments, we use actual ISP network topologies collected for the Rocketfuel project and three research network topologies.     

A study on acrylamide polymerization by anodic contact glow-discharge electrolysis: A novel tool

Contact glow-discharge electrolysis (CGDE) is an unconventional electrolytic phenomenon in which a plasma is sustained by a direct current (dc) glow-discharge between an electrode and the liquid electrolyte around it. A remarkable feature of CGDE is highly nonfaradaic chemical effects at the glow-discharge electrode. During anodic CGDE of an aqueous electrolyte, non-Faradaic yields originate mainly from reactions triggered by H^• and OH^• radicals generated in high local concentrations near the anodic plasma/liquid electrolyte interface during the process. The radical-generating potentiality of anodic CGDE was explored for the polymerization of acrylamide in aqueous media. The percentage of monomer conversion, rate of polymerization, charge efficiency, and viscometric average molar mass of the polymers produced were measured as functions of the quantities of electricity passed. The charge efficiency of the polymerization of acrylamide by anodic CGDE was at least 1 order of magnitude higher than that of ordinary electrochemically initiated polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1584–1588, 2001     

Guaranteed Performance Routing of Unpredictable Traffic With Fast Path Restoration

Two-phase routing, where traffic is first distributed to intermediate nodes before being routed to the final destination, has been recently proposed for handling widely fluctuating traffic without the need to adapt network routing to changing traffic. Preconfiguring the network in a traffic-independent manner using two-phase routing simplifies network operation considerably. In this paper, we extend this routing scheme by providing resiliency against link failures through fast path restoration along disjoint end-to-end backup paths. We view this as important progress toward adding carrier-class reliability to the robustness of the scheme so as to facilitate its future deployment in Internet service provider (ISP) networks. On the theoretical side, the main contribution of the paper is the development of linear-programming-based and fast combinatorial algorithms for two-phase routing with fast path restoration so as to minimize the maximum utilization of any link in the network, or equivalently, maximize the throughput. The algorithms developed are fully polynomial time approximation schemes (FPTAS)-for any given epsiv > 0, an FPTAS guarantees a solution that is within a (1+epsiv)-factor of the optimum and runs in time polynomial in the input size and [ 1/(relax epsiv)]. To the best of our knowledge, this is the first work in the literature that considers making the scheme resilient to link failures through preprovisioned fast restoration mechanisms. We evaluate the performance of fast path restoration (in terms of throughput) and compare it to that of unprotected routing. For our experiments, we use actual ISP network topologies collected for the Rocketfuel project and three research network topologies.     

Machine reliability and preventive maintenance planning for cellular manufacturing systems

The paper proposes a preventive maintenance (PM) planning model for the performance improvement of cellular manufacturing systems (CMS) in terms of machine reliability, and resource utilization. In a CMS, parts are processed by a group of interdependent machines, where machine reliability plays an important role in the performance improvement of the cell. Assuming that machine failure times follow a Weibull distribution, the proposed model determines a PM interval and a schedule for performing PM actions on each machine in the cell by minimizing the total maintenance cost and the overall probability of machine failures. The model uses a combined cost and reliability based approach, and optimizes maintenance costs by administering a group maintenance policy subject to a desirable machine reliability threshold. The study also proposes a CMS design model that integrates the above PM concepts into the design process. Illustrative examples are presented to demonstrate the applicability of the proposed approach.     

Analytical Solution for Power-Limited Optimal Rendezvous near an Elliptic Orbit

This paper presents an analytical solution to the problem of the optimal rendezvous using power-limited propulsion for a spacecraft in an elliptic orbit in a gravitational field. The derivation of the result assumes small relative distances, but does not make any assumption on the eccentricity of the orbit and does not require numerical integration. The results are generalized to include the possibility of different weights on the control effort for each axis (radial, along-track, and out-of-plane). When the weights on the control efforts are unequal, several integrals are used whose solutions may be represented by infinite series in a small parameter dependent on the eccentricity. A methodology is introduced where the series can be extended trivially to as many terms as desired. Furthermore, for a given numerical tolerance, an upper bound on the number of terms required to represent the series is also obtained. When the weights are equal for all the three axes, the series representations are no longer necessary. The results can be used easily to design optimal feedback controls for rendezvous maneuvers, or for generating initial guesses for two-point boundary-value problems for numerical solutions to the nonlinear rendezvous problem.     

Beurling's theorem for Riemannian symmetric spaces II

We prove two versions of Beurling's theorem for Riemannian symmetric spaces of arbitrary rank. One of them uses the group Fourier transform and the other uses the Helgason Fourier transform. This is the master theorem in the quantitative uncertainty principle.

     

A new combined stable and dispersion relation preserving compact scheme for non-periodic problems

A new compact scheme is presented for computing wave propagation problems and Navier–Stokes equation. A combined compact difference scheme is developed for non-periodic problems (called NCCD henceforth) that simultaneously evaluates first and second derivatives, improving an existing combined compact difference (CCD) scheme. Following the methodologies in Sengupta et al. [T.K. Sengupta, S.K. Sircar, A. Dipankar, High accuracy schemes for DNS and acoustics, J. Sci. Comput. 26 (2) (2006) 151–193], stability and dispersion relation preservation (DRP) property analysis is performed here for general CCD schemes for the first time, emphasizing their utility in uni- and bi-directional wave propagation problems – that is relevant to acoustic wave propagation problems. We highlight: (a) specific points in parameter space those give rise to least phase and dispersion errors for non-periodic wave problems; (b) the solution error of CCD/NCCD schemes in solving Stommel Ocean model (an elliptic p.d.e.) and (c) the effectiveness of the NCCD scheme in solving Navier–Stokes equation for the benchmark lid-driven cavity problem at high Reynolds numbers, showing that the present method is capable of providing very accurate solution using far fewer points as compared to existing solutions in the literature.     

Covariant holographic entanglement negativity

We propose a covariant holographic conjecture for the entanglement negativity of bipartite mixed states in \((1+1)\)-dimensional conformal field theories dual to bulk non static \(AdS_{3}\) configurations. Application of our conjecture to \((1+1)\)-dimensional conformal field theories dual to bulk non extremal and extremal rotating BTZ black holes exactly reproduce the corresponding entanglement negativity obtained through the replica technique, in the large central charge limit. We briefly discuss the issue of the generalization of our conjecture to higher dimensions.