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Enhancement structures for the bat algorithm
No full textBat algorithm is a recently developed swarm optimization technique which has been found to be a powerful method for multimodal optimization problems. Some of the drawbacks in standard BA are reduced convergence speed due to lack of inertia weight factor and premature convergence due to low diversification capability of the algorithm as the problem's dimension increases. This paper presents an enhanced bat algorithm (EBA) for optimization which employs five different enhancement structures to improve the standard bat algorithm for better global exploration. EBA is tested on several standard test functions and correlated with recently published studies in the literature using non-parametric statistical tests. It shown from statistical test results that EBA is often superior to the standard BA and is also computationally efficient compared to other published algorithms such as GA and PSO. © 2018 IEEE
Synthesis, cytotoxic and antioxidant activities of azolyl benzothiazine carboxamides
No full textAbstract: Azolyl benzothiazine carboxamides were prepared from benzothiazine carboxylate and azolyl amines in the presence of NaOMe under ultrasonication. 4-Bromothiophenylimidazolyl benzothiazine carboxamide (19b) and 4-bromopyrrolylimidazolyl benzothiazine carboxamide (22b) showed cytotoxic activity on HeLa cell lines (IC 50 33.75, 47.52 µM) and MCF-7 cell lines (IC 50 31.75, 34.35 µM). Furthermore, methyl-substituted furanyloxazolyl benzothiazine carboxamide (14a), furanylimidazolyl benzothiazine carboxamide (16a), thiophenyloxazolyl benzothiazine carboxamide (17a) and pyrrolyloxazolyl benzothiazine carboxamide (20a) exhibited antioxidant activity greater than ascorbic acid. Graphical abstract: Azolyl benzothiazine carboxamides are prepared from benzothiazine carboxylate and azolyl amines. Optimization of reaction conditions is established using different molar concentrations of NaOMe. Compounds 19b and 22b showed cytotoxic activity on HeLa cell lines and MCF-7 cell lines. Compounds 14a, 16a, 17a and 20a exhibited prominent antioxidant activity.Figure not available: see fulltext.. © 2019, Springer Nature B.V
Multi-layered stack consisting of PVDF nanocomposites with flow-induced oriented MWCNT structure can supress electromagnetic radiation
No full textPolymeric nanocomposites have emerged as a potential material in the electronic world owing to its numerous advantages like ease of processing, design flexibility, light-weight, ease of embedding and integrating with the existing production line. Given the surge in electronic components, electromagnetic interference, which severely impairs the reliability of precise electronic devices, has emerged as a new challenge. Hence, technologically, viable design is the need of the day. However, the high concentration of fillers required to achieve the desired properties still remains a challenge with respect to the design of functional polymeric nanocomposites. In this context herein, we report as to how flow induced distribution of multi-walled carbon nanotubes (MWCNT) in poly-vinylidene (PVDF) matrix during mechanical rolling influence the texture, polymorphism and electromagnetic shielding properties. We demonstrate the flow induced orientation of MWCNT, polymorphism in PVDF and composites shielding performance by TEM, crystallographic texture and shielding effectiveness measurements, respectively. Further, mechanical and thermal properties of as pressed and mechanically rolled samples were investigated by DMA and DSC. TEM analysis revealed that MWCNT form small aggregate, however were aligned along the rolling direction. This observation is in sharp contrast to the random distribution for as pressed samples. Quantitatively, a strong texture was observed for rolled samples as compared to as pressed samples. Absorption of EM waves is the major shielding mechanism which is mechanistically discussed here through associated dielectric loss parameters. Interactions, alignment of MWCNTs, and polymorphism influence the shielding efficiency in these composites. In addition, stacking of such nanocomposite layers further enhances the overall shielding efficiency by absorption (up to 72) due to the polarization, multiple internal reflections and interlayer charge storing capacity. A Bluetooth module was employed to successfully demonstrate the efficacy of this approach in supressing unwanted EM interference. This study comprehensively guides researchers as to how processing or flow-induced changes alter the distribution of MWCNTs in polymer composites and how this influences the overall shielding behaviour. © 2019 Elsevier Lt
Saccharification of macroalgal polysaccharides through prioritized cellulase producing bacteria
No full textMarine macroalgal cell wall is predominantly comprised of cellulose (polysaccharide) with the complex chain of glycosidic linkages. Bioethanol production from macroalgae entails breaking this complex chain into simple glucose molecule, which has been the major challenge faced by the industries. Cellulases have been preferred for hydrolysis of cellulose due to the absence of inhibitors affecting the subsequent fermentation process. Cellulose degrading bacteria were isolated from wide-ranging sources from marine habitats to herbivore residues and gastrointestinal region. The investigation reveals that Vibrio parahaemolyticus bacteria has higher hydrolytic capacity with salt tolerance up to 14 and 3.5 salinity is optimum for growth. Higher hydrolytic activity of 2.45 was recorded on carboxymethyl cellulose medium at 48 h and hydrolytic activity of 2.46 on Ulva intestinalis hydrolysate, 3.06 on Ulva lactuca hydrolysate at 72 h of incubation. Total activity of enzyme of 2.11 U/ml and specific activity of 6.05 U/mg were recorded at 24 h. Enzyme hydrolysis of macroalgal biomass; U. intestinalis and U. lactuca produced 135.9 mg/g and 107.6 mg/g of reducing sugar respectively. The study reveals that the enzyme extracted from salt tolerant Vibrio parahaemolyticus bacteria is suitable for optimal saccharification of seaweed polysaccharides towards biofuel production. © 201
Asymmetric transfer hydrogenation of ketones using Ru(0) nanoparticles modified by Chiral Thiones
No full textThe catalytic asymmetric transfer hydrogenation (ATH) of acetophenone in isopropanol by Ru(0) nanoparticles (NPs) obtained by the in-situ reduction of Ru (II) half-sandwich complexes of chiral 2-oxazolidinethiones and 2-thiozolidinethiones was examined and compared with the catalytic activity of Ru(0) NPs formed in-situ by the reduction of Ru(p-cymene)(Cl) 2 2 in presence of optically active ligands such as (S)-4-isobutylthiazolidine-2-thione, (S)-4-Isopropyl-2(�2-pyridinyl)-2-oxazoline, (8S, 9R)-(�)-cinchonidine, (S)-leucinol, (S)-phenylalaninol, and (S)-leucine. Three of the best catalytic systems were then examined for ATH of thirteen aromatic ketones with different electronic and steric properties. A maximum of 24% ee was obtained using NPs generated from the Ru (II) half-sandwich complex with (S)-4-isobutylthiazolidine-2-thione in the TH of acetophenone. The NPs were characterized by TEM and DLS measurements. Kinetic studies and poisoning experiments confirmed that the reaction is catalyzed by the chiral NPs formed in-situ. Complete characterization of the complexes, including the X-ray crystallographic characterization of two complexes, was also carried out. © 2019 John Wiley & Sons, Ltd
Discovering frequent chain episodes
No full textFrequent episode discovery is a popular framework in temporal data mining with many applications. An episode is a partially ordered set of nodes with each node associated with an event-type. The episodes literature has seen different notions of frequency and a variety of associated discovery algorithms under these different frequencies when the associated partial order is total (serial episode) or trivial (parallel episode). Recently an apriori-based discovery algorithm for mining episodes where the associated partial order has no restriction but the node to event-type association is one�one (general injective episodes) was proposed based on the non-overlapped frequency measure. This work pointed out that frequency alone is not a sufficient indicator of interestingness in the context of episodes with general partial orders and introduced a new measure of interestingness called bidirectional evidence (BE) to address this issue. This algorithm discovers episodes by incorporating both frequency and BE thresholds in the level-wise procedure. In this paper, we extend this BE-based algorithm to a much larger class of episodes that we call chain episodes. This class encompasses all serial and parallel episodes (injective or otherwise) and also many other non-injective episodes with unrestricted partial orders. We first discuss how the BE measure can be generalized to chain episodes and prove the monotonicity property it satisfies in this general context. We then describe our candidate generation step (with correctness proofs) which nicely exploits this new monotonicity property. We further describe the frequency counting (with correctness proofs) and BE computation steps for chain episodes. The experimental results demonstrate the effectiveness of our algorithms. © 2019, Springer-Verlag London Ltd., part of Springer Nature
EPR and Optical Properties of UV-B Radiation-Emitting Gd 3+ -Doped BaLa 2 ZnO 5 Host Prepared by Sol�Gel Method
No full textA series of trivalent gadolinium ion-doped BaLa 2 ZnO 5 phosphors was prepared by the sol�gel technique. Phase purity and crystal structure were confirmed by the Rietveld refinement. The morphology of the sample was studied by scanning electron microscopy. The effect of Gd 3+ concentration on the luminescence of the BaLa 2�x Gd x ZnO 5 (x = 0.01 � x � 0.15) samples was investigated by photoluminescence spectra. Under excitation at 273 nm, all the samples showed ultraviolet emission near 314 nm, generated by the 6 P 7/2 � 8 S 7/2 transition of Gd 3+ ions. It was found that the emission intensity increased with the concentration of Gd 3+ ions up to 0.15 mol without concentration quenching. The electron paramagnetic resonance spectra of the Gd 3+ ion-doped BaLa 2 ZnO 5 phosphors indicated that the dopant ions occupied slightly distorted La 3+ sites in the host lattice. Both the PL and EPR studies describe the excited and ground-state features of Gd 3+ ions in the BaLa 2 ZnO 5 host lattice. © 2019, The Minerals, Metals & Materials Society
Thermonuclear X-ray bursts in rapid succession in 4U 1636-536 with AstroSat-LAXPC
No full textWe present results from an observation of the low-mass X-ray binary 4U 1636-536 obtained with the LAXPC instrument aboard AstroSat. The observations of 4U 1636-536 made during the performance verification phase of AstroSat showed seven thermonuclear X-ray bursts in a total exposure of similar to 65 ks over a period of about two consecutive days. Moreover, the light curve of 4U 1636-536 revealed the presence of a rare triplet of X-ray bursts, having a wait time of about 5.5 min between the second and the third bursts. We also present results from time-resolved spectroscopy performed during these seven X-ray bursts. In addition, we have also detected a transient quasi-periodic oscillation at similar to 5 Hz. However, we did not find any evidence of kilo-hertz quasi-periodic oscillations and/or X-ray burst oscillations, perhaps due to the hard spectral state of the source during this observation
In-cylinder flow and combustion modeling of a CNG-fuelled stratified charge engine
No full textIn-cylinder air-fuel stratification and combustion is evaluated in a CNG-fuelled IC engine using a transient, three-dimensional, computational fluid dynamic (CFD) model. Performance of the stratified mode of operation is compared with the premixed mode. The combustion process is modeled using the extended coherent flame model (ECFM-3Z). For simulating the ignition process, the arc and kernel tracking ignition model (AKTIM) is used. The combustion model is first validated with measured in-cylinder pressure data and other derived quantities such as heat release rate and mass burn fraction for the premixed case. A good agreement is observed between measured and simulated values. It is observed that there is a marginal improvement in terms of overall engine efficiency when the stoichiometric premixed case is compared with the lean stratified condition. However, a major improvement in performance is observed when the lean stratified case is compared with lean premixed condition. The stratified case shows a faster heat release rate which could potentially translate to lower cycle-to-cycle variations in actual engine operation. Also, the stratified cases show as much as 30% lower in cylinder NOx emissions when compared with the premixed case at the same engine load and speed, underscoring the potential of in-cylinder stratification to achieve improved performance and lower NOx emissions
A new species of rock-dwelling Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) from Tamil Nadu, southern India
No full textA new species of the gekkonid genus Cnemaspis is described based on a series of nine specimens from near Sankari in Salem district, Tamil Nadu state, southern India. The new species is diagnosable by the following suite of characters: a small-sized Cnemaspis (adult snout to vent length less than 33 mm); heterogeneous dorsal pholidosis consisting of weakly keeled granular scales intermixed with large strongly keeled, conical tubercles, 9-11 rows of dorsal tubercles, 12-17 tubercles in paravertebral rows; spine-like scales absent on flank, 17-20 lamellae under digit IV of pes. Males with 4-6 femoral pores on each thigh, separated on either side by eight poreless scales from four precloacal pores; precloacal pores separated medially by a single poreless scale; two single dorsal ocelli on occiput and between forelimb insertions, two pairs of ocelli on either side just anterior and posterior to forelimb insertions. Cnemaspis agarwali sp. nov. is the fifth endemic species of Cnemaspis from peninsular India outside the Western Ghats and highlights the rich and unique diversity of this understudied region