Mode matching analysis for wave scattering in triple and pentafurcated spaced ducts

We present solutions to both trifurcated and pentafurcated spaced waveguides using the mode matching (or eigenfunction expansion) method. While the trifurcated problem with mean fluid flow has been solved previously using the Wiener–Hopf technique, we solve this problem to validate and demonstrate our method. We then show how we can easily generalize the method to the pentafurcated problem that has not been solved previously. We observe that mode matching method is easier to derive and generalize than the Wiener–Hopf technique. We also investigate the numerical solution in detail for various geometries to model practical exhaust systems. Copyright © 2015 John Wiley & Sons, Ltd.     

Evaluation of in vivo hypoglycemic potential of 4-ethyloxychalcone in alloxan-induced diabetic rats

The presently available therapies for type 2 diabetes have not been able to achieve normoglycemic status in a majority of the patients which may be either due to the limitations of the drug itself or its side effects. In an effort to develop potent and safe oral antidiabetic agents, 4-ethyloxychalcone, which was found to be the most potent antiglycating agent in our previous study, has been evaluated for its in vivo hypoglycemic activity using an alloxanized diabetic rat model. The diabetes was induced in rats by injection of intraperitoneal alloxan. However, the oral route was used for the administration of 4-ethyloxychalcone. A significant glucose-lowering effect (P < 0.05) comparable with the standard glibenclamide has been observed for 4-ethyloxychalcone in an oral glucose tolerance test. 4-Ethyloxychalcone also produced a significant decrease (P < 0.05) in fasting blood glucose levels during the 42 days of treatment. Furthermore, a significant lowering (P < 0.05) of glycated hemoglobin (HbA_1C ) level was also shown by 4-ethyloxychalcone after 42 days of treatment. Thus, 4-ethyloxychalcone might be regarded as a potential hypoglycemic agent that can act as a platform for the development of future antidiabetic drugs.     

Gracilone,a new sesquiterpene lactone from Tanacetum gracile (Tansies)

The methanolic extract of the Tanacetum gracile afforded the isolation of new sesquiterpene lactone, named gracilone (1) along with four known compounds as 14α-taraxeran-3-one (2), 14α-taraxeran-3-ol (3), apigenin (4) and β-sitosterol (5). The structure of compound 1 was elucidated on the basis of 1D, 2D NMR and MS spectroscopic analysis. Antimicrobial, antioxidant and anticancer activities of all compounds were evaluated, from which gracilone (1) showed a moderate antibacterial activity, while apigenin (4) showed comparatively more antibacterial activity against both gram­positive and gram­negative tested strains.     

Ethambutol: A new and effective corrosion inhibitor of mildsteel in acidic medium

Point of present exploration was to figure out the anti corrosion activity of a drug namely Ethambutol on mildsteel in acidic medium as an eco friendly corrosion inhibitor by using weight loss technique, quantum chemical studies and infrared spectral analysis. The results demonstrated that the drug showed highest inhibition efficiency 91.30% at 1000 ppm concentration at 30°C. The increase in temperature lead to decrease in inhibition efficiency and increase in time of immersion lead to increase in inhibition efficiency.     

The self-ordering properties of novel phthalocyanines with out-of-plane alkyl substituents

Two novel homologous series of phthalocyanines were prepared from 2,2-dialkylindane and 2,2-dialkyl-1,3-benzodioxole precursors. It was anticipated that attaching alkyl chains to five-membered rings, fused to the peripheral sites of the phthalocyanine ring, would result in the adoption of an out-of-plane configuration and thereby discourage cofacial aggregation, to provide an analogy with picket-fence porphyrins. This strategy proved partially successful. Some members of the series of phthalocyanines derived from 2,2-dialkyl-1,3-benzodioxoles, in which the alkyl chains are linked to the phthalocyanine via a cyclic ketal, form spin-coated thin films in which the phthalocyanine cores are perfectly isolated. This behaviour is associated with the formation of a disordered crystal that appears as a mesophase in the thermal profile of these materials. However, the phthalocyanines derived from 2,2-dialkylindanes display a columnar mesophase over a wide temperature range, with some liquid crystalline derivatives at ambient temperature. A single-crystal X-ray diffraction structure of the octahexyl derivative of this series shows how the columnar assembly accommodates the out-of-plane alkyl chains by tilting the macrocyclic plane of the phthalocyanine components with respect to the axis of the column. This study helps to emphasise the importance of both the steric and electronic effects of substituents on the packing behaviour of phthalocyanines in the condensed phase, and especially the role of electron-donating oxygen atoms directly attached to the ring.     

A method for the low-level (ng/g) determination of perfluorooctanoate in carpet by LC-MS-MS using matrix extracted standards

Fluorotelomer-based acrylic polymers are applied to the surface of carpet to impart oil, stain, and water repellence properties. Concerns that fluorotelomer-based polymers are a possible source of "low level" exposure to humans, coupled with their widespread use have prompted the need to develop a method to detect and measure perfluorooctanoate (PFO) in carpet. A liquid chromatography tandem mass spectrometry method for the determination of PFO in carpet using a dual labeled 13C-perfluoroctanoic acid (13C-PFOA) internal standard is successfully developed and validated. Levels of PFO are determined using a gradient, reversed-phase high-performance liquid chromatography (HPLC) method with acetic acid acidified water-methanol, separated on a 50 mm Phenomenex Synergi Polar RP column. Ions monitored are 413 (parent) and 369 (daughter) for PFO and 415 (parent) and 370 (daughter) for dual labeled 13C-PFOA internal standard. Accuracy and precision over three days for 5 to 900 ng/g PFO in carpet ranged from 2.4% to 7.6% and 3.7% to 14.1%, respectively. Overall extraction efficiency for samples (n=30) fortified with 13C-PFOA at 20 ng/g and perfluorooctanoic acid (PFOA) at 5, 50, and 500 ng/g is 98.9%+/-8.1%. Specificity of the method was evaluated with two different carpet samples.     

Non-similar mixed convection analysis for magnetic flow of second-grade nanofluid over a vertically stretching sheet

The aspiration of this research is to explore the impact of non-similar modeling for mixed convection in magnetized second-grade nanofluid flow. The flow is initiated by the stretching of a sheet at an exponential rate in the upward vertical direction. The buoyancy effects in terms of temperature and concentration differences are inserted in the $x$-momentum equation. The aspects of heat and mass transfer are studied using dimensionless thermophoresis, Schmidt and Brownian motion parameters. The governing coupled partial differential system (PDEs) is remodeled into coupled non-similar nonlinear PDEs by introducing non-similar transformations. The numerical analysis for the dimensionless non-similar partial differential system is performed using a local non-similarity method via bvp4c. Finally, the quantitative effects of emerging dimensionless quantities on the non-dimensional velocity, temperature and mass concentration in the boundary layer are conferred graphically, and inferences are drawn that important quantities of interest are substantially affected by these parameters. It is concluded that non-similar modeling, in contrast to similar models, is more general and more accurate in convection studies in the presence of buoyancy effects for second-grade non-Newtonian fluids.     

Stability in terms of two measures for perturbed impulsive delay integro-differential equations

In this paper, we study the stability criteria in terms of two measures for perturbed delay integro-differential equations with fixed moments of impulsive effect by using variational Lyapunov method together with a comparison principle.     

Multi-material bio-fabrication of hydrogel cantilevers and actuators with stereolithography

Cell-based biohybrid actuators are integrated systems that use biological components including proteins and cells to power material components by converting chemical energy to mechanical energy. The latest progress in cell-based biohybrid actuators has been limited to rigid materials, such as silicon and PDMS, ranging in elastic moduli on the order of mega (10(6)) to giga (10(9)) Pascals. Recent reports in the literature have established a correlation between substrate rigidity and its influence on the contractile behavior of cardiomyocytes (A. J. Engler, C. Carag-Krieger, C. P. Johnson, M. Raab, H. Y. Tang and D. W. Speicher, et al., J. Cell Sci., 2008, 121(Pt 22), 3794-3802, P. Bajaj, X. Tang, T. A. Saif and R. Bashir, J. Biomed. Mater. Res., Part A, 2010, 95(4), 1261-1269). This study explores the fabrication of a more compliant cantilever, similar to that of the native myocardium, with elasticity on the order of kilo (10(3)) Pascals. 3D stereolithographic technology, a layer-by-layer UV polymerizable rapid prototyping system, was used to rapidly fabricate multi-material cantilevers composed of poly(ethylene glycol) diacrylate (PEGDA) and acrylic-PEG-collagen (PC) mixtures. The incorporation of acrylic-PEG-collagen into PEGDA-based materials enhanced cell adhesion, spreading, and organization without altering the ability to vary the elastic modulus through the molecular weight of PEGDA. Cardiomyocytes derived from neonatal rats were seeded on the cantilevers, and the resulting stresses and contractile forces were calculated using finite element simulations validated with classical beam equations. These cantilevers can be used as a mechanical sensor to measure the contractile forces of cardiomyocyte cell sheets, and as an early prototype for the design of optimal cell-based biohybrid actuators.     

Ca2CoNbO6: A new monoclinically distorted double perovskite

The new Ca₂CoNbO₆ double perovskites has been synthesized by solid-state reaction and its crystal structure has been refined using X-ray powder diffraction data. Rietveld fit to the diffraction data shows that the compound is monoclinically distorted and adopts space group P21/n. The cell parameters are: a = 5.4797(1) Å, b = 5.6051(1) Å, c = 7.8119(2) Å, β = 89.96(1)°. The Co and Nb are found to be distributed over the six coordinated octahedral sites in rock salt arrangement. However, nearly identical ionic radii of Co and Nb lead to severe degree of anti-site disorder (31%). The refined Co–O and Nb–O bond lengths are 1.9788(2) Å and 2.0642(2) Å respectively.