Dependence of Exchange Bias on Interparticle Interactions in Co/CoO Core/Shell Nanostructures

This article reports the dependence of exchange bias (EB) effect on interparticle interactions in nanocrystalline Co/CoO core/shell structures, synthesized using the conventional sol-gel technique. Analysis via powder X-Ray diffraction (PXRD) studies and transmission electron microscope (TEM) images confirm the presence of crystalline phases of core/shell Co/CoO with average particle size ≈ 18 nm. Volume fraction (φ) is varied (from 20% to 1%) by the introduction of a stoichiometric amount of non-magnetic amorphous silica matrix (SiO2) which leads to a change in interparticle interaction (separation). The influence of exchange and dipolar interactions on the EB effect, caused by the variation in interparticle interaction (separation) is studied for a series of Co/CoO core/shell nanoparticle systems. Studies of thermal variation of magnetization (M−T) and magnetic hysteresis loops (M−H) for the series point towards strong dependence of magnetic properties on dipolar interaction in concentrated assemblies whereas individual nanoparticle response is dominant in isolated nanoparticle systems. The analysis of the EB effect reveals a monotonic increase of coercivity (HC) and EB field (HE) with increasing volume fraction. When the nanoparticles are close enough and the interparticle interaction is significant, collective behavior leads to an increase in the effective antiferromagnetic (AFM) CoO shell thickness which results in high HC and HE. Moreover, in concentrated assemblies, the dipolar field superposes to the local exchange field and enhances the EB effect contributing as an additional source of unidirectional anisotropy

Antibacterial Activity of Murrayaquinone A and 6-Methoxy-3,7-dimethyl-2,3-dihydro-1H-carbazole-1,4(9H)-dione

The antibacterial activity of Murrayaquinone A (10), a naturally occurring carbazoloquinone alkaloid, and 6-methoxy-3,7-dimethyl-2,3-dihydro-1H-carbazole-1,4(9H)-dione (11), a synthetic carbazoloquinone, both obtained during the development of the synthesis of Carbazomycin G, having unique quinone moiety, was studied against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas sp.) bacteria. Compound 10 showed antibacterial activities against both of Escherichia coli and Staphylococcus aureus whereas compound 11 indicated the activity against Staphylococcus aureus only. Both compounds 10 and 11 exhibited minimum inhibitory concentration (MIC) of 50 μg mL−1 against Staphylococcus aureus

Montmorillonite-KSF induced Fischer indole cyclization under microwave towards a facile entry to 1-keto-1,2,3,4-tetrahydrocarbazoles

201-206Fischer indole cyclization of substituted cyclohexane-1,2-dione-1-phenylhydrazones 1 having either electron donating or electron withdrawing group on the phenyl moiety of substituted 1-keto-1,2,3,4-tetrahydrocarbazoles 2 are efficiently carried out by microwave irradiation  in presence of montmorillonite-KSF under solvent free condition

AN EFFICIENT FRAMEWORK TO IDENTIFY QUALITY ATTRIBUTES AND TO PROVIDE FLEXIBILITY IN DEVELOPMENT

Non Functional Requirements (NFRs) are gaining importance for high quality software development and also gaining interests in the competitive market. To enhance the quality of a software project along with its quantity, a framework is necessary to identify the correct NFRs and implement them in the appropriate way to the architectural models. This work provides a framework to identify and measure the appropriate NFRs thoroughly; those are successfully carried out on a case study to validate them. Effective measurement techniques are used to identify and implement NFRs appropriately, that will not only provide flexibility in the development cycles but also increases the cost effectiveness of the project

Evaluation of antimicrobial activity of synthesized fluorocarbazole derivatives based on SAR

701-708The antimicrobial activity of synthesized 6-fluoro-1H-carbazole, 6-fluoro-2-methyl-1H-carbazole, 6-fluoro-3-methyl-1H-carbazole and their respective quinone derivatives 6-fluoro-1H-carbazole-1,4(9H)-dione, 6-fluoro-2-methyl-1H-carbazole-1,4(9H)-dione and 6-fluoro-3-methyl-1H-carbazole-1,4(9H)-dione have been studied against Escherichia coli (MTCC 42), Bacillus subtilis (MTCC 121), Staphylococcus aureus (MTCC 96), Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas sp. (MTCC 6199). The experimental results show that methylsubstituent at C-2 and C-3 along with electron withdrawing fluorine atom at C-6 in the carbazoloquinone as well as the corresponding carbazoles result in the remarkable antibacterial activity against MRSA. This finding is expected to fuel the existing structure-activity relationship for drug designing concept

Solid Phase Benzoylation of Phenols and Alcohols in Microwave Reactor: An Eco-Friendly Protocol

<div><p></p><p>An efficient solid phase benzoylation of phenols and alcohols was developed under microwave irradiation. Stoichiometric amount of benzoyl chloride was sufficient to carry out the reaction. This benzoylation features short reaction time, high yields and easy work-up procedures. Furthermore, the scope of the reaction was extended to prepare 3,5-dinitrobenzoyl derivatives of alcohols.</p></div

Generation of Non-Linear Technique Based 6 Hourly Wind Reanalysis Products Using SCATSAT-1 and Numerical Weather Prediction Model Outputs

We combined observations of ocean surface winds from Indian SCATterometer SATellite-1 (SCATSAT-1) with a background wind field from a numerical weather prediction (NWP) model available at National Centre for Medium-Range Weather Forecast (NCMRWF) to generate a 6-hourly gridded hybrid wind product. A distinctive feature of the study is to produce a global gridded wind field from SCATSAT-1 scatterometer passes with spatio-temporal data gaps at regular synoptic hours relevant for forcing models and other NWP studies. We are following the concept from the modern particle filter technique, which does not represent the model probability density function (PDF) as Gaussian. We generated the 6-hourly hybrid winds for 2018 and validated them using the wind speed from daily gridded level-4 SCATSAT-1 winds (L4AW), Cross Calibrated Multi-Platform (CCMP) dataset and global buoy data from National Data Buoy Centre (NDBC). The results suggest the potential of the technique to produce scatterometer winds at the desired temporal frequency with significantly less noise and bias along the swath. The study shows that the generated hybrid winds are of prime quality compared with the already existing daily products available from Indian Space Research Organization (ISRO)

Dependence of Exchange Bias on Interparticle Interactions in Co/CoO Core/Shell Nanostructures

This article reports the dependence of exchange bias (EB) effect on interparticle interactions in nanocrystalline Co/CoO core/shell structures, synthesized using the conventional sol-gel technique. Analysis via powder X-Ray diffraction (PXRD) studies and transmission electron microscope (TEM) images confirm the presence of crystalline phases of core/shell Co/CoO with average particle size &asymp; 18 nm. Volume fraction (&phi;) is varied (from 20% to 1%) by the introduction of a stoichiometric amount of non-magnetic amorphous silica matrix (SiO2) which leads to a change in interparticle interaction (separation). The influence of exchange and dipolar interactions on the EB effect, caused by the variation in interparticle interaction (separation) is studied for a series of Co/CoO core/shell nanoparticle systems. Studies of thermal variation of magnetization (M&minus;T) and magnetic hysteresis loops (M&minus;H) for the series point towards strong dependence of magnetic properties on dipolar interaction in concentrated assemblies whereas individual nanoparticle response is dominant in isolated nanoparticle systems. The analysis of the EB effect reveals a monotonic increase of coercivity (HC) and EB field (HE) with increasing volume fraction. When the nanoparticles are close enough and the interparticle interaction is significant, collective behavior leads to an increase in the effective antiferromagnetic (AFM) CoO shell thickness which results in high HC and HE. Moreover, in concentrated assemblies, the dipolar field superposes to the local exchange field and enhances the EB effect contributing as an additional source of unidirectional anisotropy