Complex two-unit system with preventive maintenance

A two-unit warm standby redundant system with repair and preventive maintenance is considered. The pdf of the life time of a unit while in standby is assumed to be Erlangian. The pdfs of all the other random variables are arbitrary. Identifying suitable regeneration points, expressions for the Laplace transforms of the availability and reliability of the system are derived.     

Synthesis,Characterization and Wire Electric Erosion Behaviour of AA7178-10 wt.% ZrB2 Composite

Silicon - In this work, AA7178-10 wt.% ZrB2 Metal Matrix Composite was produced using stir casting route and the mechanical properties of the composites were studied. The microstructure and...     

Transient analysis of super conducting fault current limiter integrated with multi-terminal direct current system

Since the extension of voltage source converter (VSC) based high voltage direct current (HVDC) transmission system to multi-terminal direct current (MTDC) system is easy, the application of MTDC system is more attractive than before. But the VSC based HVDC system is more vulnerable to DC line faults due to the high discharge current from the DC link capacitance. In this aspect, a super conducting fault current limiter (SCFCL) is a better choice to reduce the consequences of DC line faults. The main objective of this paper is to improve the dynamic performance of an offshore wind farm connected multi-terminal VSC-HVDC transmission system by incorporating SCFCL at different locations. Here, the SCFCL integrated MTDC system is modelled in MATLAB/Simulink and the results are presented for various AC/DC fault conditions.     

Structural Analysis of Inclusions in β-Silicon Carbide Whiskers Grown from Rice Hulls

Microcrystalline inclusions in the core of β-SiC whiskers derived from the pyrolysis of rice hulls have been studied by transmission electron microscopy using conventional brightfield and dark-field imaging. The electron diffraction patterns from the whiskers show extra reflections arising from these inclusions. Dark-field images from these reflections are consistent with the presence of three different variants of inclusions, all of which are oriented with their [001] axes parallel to the heavily faulted [111] growth axis of the whiskers. A structural model for these inclusions is proposed which accounts satisfactorily for the extra reflections in the electron diffraction patterns.     

Biocompatible tumor micro-environment responsive CS-g-PNIPAAm co-polymeric nanoparticles for targeted Oxaliplatin delivery

The objective of the research study was to develop and characterize a biodegradable, thermo and pH dual responsive Oxaliplatin-loaded chitosan-graft-poly-N-isopropylacrylamide (CS-g-PNIPAAm) co-polymeric nanoparticles as a tumor-targeting drug delivery system. CS-g-PNIPAAm co-polymers were synthesized, characterized and optimized its thermo and pH responsive properties for tumor microenvironment conditions. Optimized co-polymer could be efficiently loaded with Oxaliplatin in nanoparticle form, evaluated for their morphology (TEM), particle size, zeta potential, loading efficiency and drug content. In vitro drug release study at tumor microenvironment and physiological pH and temperature conditions. The in vitro drug release was optimal at above lower critical solution temperature (LCST) and tumor microenvironment pH when compared to physiological pH & temperature. MTT assay and fluorescence microscopic study showed that drug release and cell uptake was significantly enhanced in tumor microenvironment. In conclusion, the obtained nanoparticles appeared to be of great promise in tumor targeted drug delivery of oxaliplatin.     

The pH-dependence of thermally-coated Ti/TiO2 electrodes in the absence and presence of nitrobenzene

Cyclic voltammetric measurements on thermally coated Ti/TiO₂ electrodes in 0.05–3.0 m H₂SO₄, Na₂SO₄ and NaOH media were carried out to evaluate the cause of pH sensitivity of these electrodes. The electrode activity decreased in the order H₂SO₄ > NaOH > Na₂SO₄. Ionic strength had a significant influence on the electrode activity. In the redox catalysis of nitrobenzene reduction the pH dependence increased significantly. The electrode activity again decreased in the same order. In acid media the TiO₂ surface is protonated. In alkaline media OH- ions are specifically adsorbed on the TiO₂ surface. The concentration of these charged species, as well as the ease of counter ion transport through the charged layers during surface redox reactions in the oxide layer, is identified as the cause of the pH sensitivity of the electrodes. In acid media proton transport in the film occurs through a surface Grothus-like mechanism. In alkaline medium proton abstraction by OH^– ions from the trapped H₂O molecules may facilitate proton transport.     

Radical polymerization approach for ring opened oxanorbornene anhydride based macromonomers

In this work, we synthesized end group functionalization of the cis-Norbornene-5-6-endo-dicarboxylic anhydride species via the ring-opening metathesis polymerization (ROMP) of oxanorbornene derivatives generated a chiseled poly(cis-Norbornene-5-6-endo-Dicarboxylic anhydride) acrylate macromonomer. Further, acrylate oxanorbornene based macromonomer further polymerized via reversible addition fragmentation chain transfer (RAFT) polymerization technique. Chain transfer is exhibited in the structure during the radical polymerizations so that free radical polymerization could also be used to comb structure copolymers with a PDI value below 1.2 with the help of acrylate oxanorbornene. Atomic force microscopy reveals the comb shape of branched polymer brushes structure. This method involves polymerizable end-group attachment to a macromonomer, and the backbone of the comb polymer is created in a second step of the polymerization. We believe that this kind of comb structured polymers can be considered for different biological applications.     

Carbohydrate crosslinked biocompatible polyurethanes: Synthesis,characterization, and drug delivery studies

A series of novel polyurethanes (PUs) with carbohydrate crosslinkers was synthesized. The drug loading and release kinetics were studied by using lamotrigine as a model drug. The polymers were designed in such a way that the drug release was tailored by differences in the stoichiometry of polymers. All the PUs were characterized for thermal and morphological properties by using differential scanning calorimetry and thermogravimetric analysis and scanning electron microscope , respectively. The encapsulation of drug inside PU matrix was confirmed via Fourier transform ‐ infrared (FT‐IR) spectra and scanning electron microscope . The kinetics and release mechanisms were observed to be a function of stoichiometric parameters such as type of crosslinker, polyol/crosslinker ratio and polyol/chain extender ratio. All the PUs were observed to be non‐cytotoxic in normal lung cell line L132. The synthesized PUs exhibited good mechanical strength, tunable release rates and biocompatibility that can be utilized in biomedical applications like wound dressing, biomedical implants , and drug delivery carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42223.     

Industrial scale synthesis of few-layer graphene nanosheets (FLGNSs): an exploration of electrochemical exfoliation approach

Journal of Applied Electrochemistry - Industrial scale manufacturing with tunable properties of graphene nano-sheets has been a practical concern in many applications. This study focuses on, a...     

Experimental Investigation and Analysis of Properties and Dry Sliding Wear Behavior of Al -Fe-Si Alloy Matrix Composites

Silicon - Aluminium alloy finds widespread applications in numerous engineering industries because of its tremendous properties. However aluminium alloy possess poor wear resistance. This study...