A general framework for process scheduling

Existing methods for process scheduling can be broadly classified as network‐based or sequential. The former are used to address problems where different batches of the same or different tasks are freely mixed or split, whereas the latter are used to address problems where batch mixing/splitting is not allowed. A framework is proposed that allows us to: (1) express scheduling problems in facilities that consist of network and sequential, as well as continuous subsystems, (2) formulate mixed‐integer programming (MIP) scheduling models for such problems, and (3) solve the resulting MIP formulations effectively. The proposed framework bridges the gap between network and sequential approaches, thereby addressing the major formulation challenge in the area of process scheduling, namely, the development of a framework that can be used to address a wide spectrum of problems. © 2010 American Institute of Chemical Engineers AIChE J, 57: 695–710, 2011     

Synthesis and characterization of hydroxyapatite/carboxylic acid functionalized MWCNTS composites and its triple layer coatings for biomedical applications

Introduction

Achievement of bioactive coatings on metallic implant surface with higher adhesive strength and corrosive resistance was one of the main challenges for the current biomaterial researchers. Hydroxyapatite was one of the promising bioactive ceramic which can be applied as a coating on the metallic substrate due to its similarity with the human bone.

Development of an Efficient G‐Quadruplex‐Stabilised Thrombin‐Binding Aptamer Containing a Three‐Carbon Spacer Molecule

The thrombin‐binding aptamer (TBA), which shows anticoagulant properties, is one of the most studied G‐quadruplex‐forming aptamers. In this study, we investigated the impact of different chemical modifications such as a three‐carbon spacer (spacer‐C₃), unlocked nucleic acid (UNA) and 3′‐amino‐modified UNA (amino‐UNA) on the structural dynamics and stability of TBA. All three modifications were incorporated at three different loop positions (T3, T7, T12) of the TBA G‐quadruplex structure to result in a series of TBA variants and their stability was studied by thermal denaturation; folding was studied by circular dichroism spectroscopy and thrombin clotting time. The results showed that spacer‐C₃ introduction at the T7 loop position (TBA‐SP7) significantly improved stability and thrombin clotting time while maintaining a similar binding affinity as TBA to thrombin. Detailed molecular modelling experiments provided novel insights into the experimental observations, further supporting the efficacy of TBA‐SP7. The results of this study could provide valuable information for future designs of TBA analogues with superior thrombin inhibition properties.     

Integration of functional reliability analysis with hardware reliability: An application to safety grade decay heat removal system of Indian 500 MWe PFBR

A passive system can fail either due to classical mechanical failure of components, referred to as hardware failure, or due to the failure of physical phenomena to fulfill the intended function, referred to as functional failure. In this paper a methodology is discussed for the integration of these two kinds of unreliability and applied to evaluate the integrated failure probability of the passive decay heat removal system of Indian 500 MWe prototype fast breeder reactor (PFBR). The probability of occurrence of various system hardware configurations is evaluated using the fault tree method and functional failure probabilities on the corresponding configurations are determined based on the overall approach reported in the reliability methods for passive system (RMPS) project. The variation of functional reliability with time, which is coupled to the probability of occurrence of various hardware system configurations is studied and incorporated in the integrated reliability analysis. It is observed that this consideration of the dependence of functional reliability on time will give significant advantages on system reliability. The integrated reliability analysis is also explained using an event tree. The impact of the provision for forced circulation in the primary circuit on functional reliability is also studied with this procedure and it is found that the forced circulation capability helps to bring down the total decay heat removal failure probability by lowering the peak temperatures after the reactor shut down.     

Thiophene-Based Dual Modulators of Aβ and Tau Aggregation

Alzheimer's disease is characterized by the accumulation of amyloid beta (Aβ) and Tau aggregates in the brain, which induces various pathological events resulting in neurodegeneration. There have been continuous efforts to develop modulators of the Aβ and Tau aggregation process to halt or modify disease progression. A few small-molecule-based inhibitors that target both Aβ and Tau pathology have been reported. Here, we report the screening of a targeted library of small molecules to modulate Aβ and Tau aggregation together with their in vitro, in silico and cellular studies. In vitro ThT fluorescence assay, dot blot assay, gel electrophoresis and transmission electron microscopy (TEM) results have shown that thiophene-based lead molecules effectively modulate Aβ aggregation and inhibit Tau aggregation. In silico studies performed by employing molecular docking, molecular dynamics and binding-free energy calculations have helped in understanding the mechanism of interaction of the lead thiophene compounds with Aβ and Tau fibril targets. In cellulo studies revealed that the lead candidate is biocompatible and effectively ameliorates neuronal cells from Aβ and Tau-mediated amyloid toxicity.     

Online APAN IPv6 Network Monitoring

APAN [4] has native IPv6 network across all major APAN exchange points. It is important to validate the performance of the links in the network to ensure the link stability. This paper discusses the technique and mechanism that are used to perform online monitoring of the APAN IPv6 network status. Pchar tool is used to check the performance of the network. Metrics such as bandwidth, hop count and round trip time between nodes in each country's have been adopted for these monitoring activity.     

Growth and Optical Studies of a Novel Organometallic Complex NLO Crystal: Tetrathiourea Cadmium(II) Tetrathiocyanato Zinc(II)

Tetrathiourea cadmium(II) tetrathiocyanato Zinc(II) (TCTZ) single crystals were grown in acetone-water mixture solvent using slow solvent evaporation technique and their optical property was studied for the first time. Both thiourea and thiocyanate ligands were combined with the transition metal ions Cd²⁺ and Zn²⁺. The nonlinear optical (NLO) efficiency of TCTZ crystal was tested and measured using Kurtz and Perry technique. The dielectric behavior of the sample was also studied.     

Electrochemical and oxygen reduction behaviour of solid silver-bismuth/antimony electrodes in KOH solutions

Oxygen reduction behaviour at silver-low bismuth/antimony electrodes was investigated by electrochemical methods in KOH solutions. The electrochemical redox characteristics such as peak multiplicity, peak currents and peak potentials on these electrodes under both potentiostatic steady state and cyclic voltammetric conditions were obtained. The anomalies associated with the redox peak potential values both in the anodic and cathodic branches of the cyclic voltammograms were attributed to the distinct electrochemical behaviour of bismuth/antimony on the electrode surface along with silver. The behaviour of these electrodes for the electrocatalytic cathodic reduction of oxygen was also investigated both by potentiostatic steady state and cyclic voltammetric techniques under rotating conditions. The kinetic parameters corresponding to the electrochemical reduction of oxygen on these electrodes were obtained. These electrodes were ranked with respect to their electrocatalytic activity both for the oxygen reduction and evolution reactions.