First report of isolation of maleamic acid from natural source Polygonatum cirrhifolium—A potential chemical marker for identification

Polygonatum cirrhifolium (Meda) plant is being used in number of rejuvenating Ayurvedic formulations. Ever rising demands, lack of natural sources, and insufficient quantity, to meet the requirements of market, the raw material has led toward the use of official substitutes recommended by the Department of AYUSH that has further encouraged manufacturers for adulteration of formulations by other substandard/spurious raw drugs. Literature reveals that more than 60% Ayurvedic parameters as well as pharmacological actions of Ashtawarga plants do not match with their substitutes leading to reduced efficacy of the drugs along with loss of faith for use of herbal drugs. Consumers are forced to pay for the material which has never been used for high-cost claimed formulation. The situation is being exploited by manufacturers because regulatory authorities lack the tools (marker compound) needed for identification of authentic plant. Methanolic extract of rhizomes of plant was subjected to column chromatography. Isolated compound has been characterized as (Z)-4-amino-4-oxobut-2-enoic acid (maleamic acid/maleamate/maleic monoamide/maleic acid monoamide) by chemical test, melting point, IR/NMR/mass/UV spectral analysis. It is the first report in Polygonatum genus and can be used as a marker for identification of the plant in market formulations.     

Multi-objective Geometry Optimization of a Gas Cyclone Using Triple-Fidelity Co-Kriging Surrogate Models

Cyclone separators are widely used in a variety of industrial applications. A low-mass loading gas cyclone is characterized by two performance parameters, namely the Euler and Stokes numbers. These parameters are highly sensitive to the geometrical design parameters defining the cyclone. Optimizing the cyclone geometry therefore is a complex problem. Testing a large number of cyclone geometries is impractical due to time constraints. Experimental data and even computational fluid dynamics simulations are time-consuming to perform, with a single simulation or experiment taking several weeks. Simpler analytical models are therefore often used to expedite the design process. However, this comes at the cost of model accuracy. Existing techniques used for cyclone shape optimization in literature do not take multiple fidelities into account. This work combines cheap-to-evaluate well-known mathematical models of cyclones, available data from computational fluid dynamics simulations and experimental data to build a triple-fidelity recursive co-Kriging model. This model can be used as a surrogate with a multi-objective optimization algorithm to identify a Pareto set of a finite number of solutions. The proposed scheme is applied to optimize the cyclone geometry, parametrized by seven design variables.     

A Bianchi type-II dark-energy cosmology with a decaying Λ-term in the Brans–Dicke theory of gravity

We present a sequence of anisotropic Bianchi type-II dark-energy models in the framework of the Brans–Dicke theory of gravity with a variable equation of state (EoS) parameter and a constant deceleration parameter. We use power-law relations between the scalar field φ and the scale factor A and between the average Hubble parameter H and the average scale factor A to obtain most of the analytic solutions. The dark-energy EoS parameter ω and its range admitted by the models agrees well with the most recent observational data. It has been observed that the cosmological constant Λ is decreasing with time, which is consistent with recent cosmological observations. We study the dynamical stability and physical features of the models.     

Wave propagation in an incompressible transversely isotropic fibre-reinforced elastic media

The boundary conditions at free surface of an incompressible, transversely isotropic elastic half-space are satisfied to obtain the reflection coefficients for the case when outer slowness section is re-entrant. Two quasi-shear waves will be reflected for an angular range of direction of incident wave. The numerical illustrations of reflection coefficients are presented graphically for three arbitrary materials.     

A study of the freezing of binary solutions saturating a porous matrix

The freezing of a binary solution saturating a porous matrix is investigated experimentally and numerically. An aqueous solution of sodium chloride constituted the binary solution. Spherical glass beads constituted the porous matrix. The freezing was initiated at one of the vertical walls of a rectangular cavity. The temperature distribution in the solid, liquid and mush regions were recorded. A mathematical model that considered conduction as the only mode of heat transfer was developed. The predictions of the model were compared with experimental data. In general, as the model were compared with experimental data. In general, as the model ignored natural convection, the predicted temperatures agreed well with the data during early times in the freezing when conduction was the dominant mode of heat transfer. But as freezing progressed the predictions departed from the data and this departure was larger when the initial superheat was high i.e., when the natural convective flow was vigorous and its influence strong on the freezing process.

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Untersuchung des Gefriervorgangs in einem mit binärer Flüssigkeit getränkten porösen Körper

Zusammenfassung Der Gefriervorgang in einem mit einer binären Flüssigkeit getränkten porösen Körper wurde experimentell und numerisch untersucht. Eine wässerige Lösung von Natriumchlorid bildete die Binärlösung, während eine Glaskugelschüttung den porösen Körper repräsentierte. Der Gefriervorgang wurde an einer der senkrechten Wände einer rechteckigen Vertiefung eingeleitet und die Temperaturverteilung in der Fest-, Flüssig- und Mischphase gemessen. Das zur Überprüfung der experimentell gefundenen Ergebnisse dienende mathematische Modell unterstellte Wärmeleitung als einzigen Wärmetransportmechanisms. Da zu Beginn des Gefriervorgangs die im Modell vernachlässigte natürliche Konvektion gegenüber der Wärmeleitung von geringem Einfluß ist, zeigte sich in diesem Bereich gute Übereinstimmung zwischen Theorie und Experiment. Mit fortschreitendem Gefriervorgang traten immer größere Abweichungen auf, besonders wenn die Anfangsüberhitzung hoch war und folglich die natürliche Konvektionsströmung starken Einfluß auf den Gefriervorgang nahm.

     

Meshless method for nonlinear heat conduction analysis of nano-composites

Carbon nanotubes (CNTs) may become ideal reinforcing materials for high-performance nano-composites due their exceptional properties. Still, much work is needed to be done before the potentials of CNT based composites can be fully realized. The evaluation of effective material properties of nano-composites is one of many difficult tasks. Simulations using continuum mechanics approach can play a significant role in the analysis of these composites. In the present work, nonlinear heat conduction analysis of CNT based composites has been carried out using continuum mechanics approach. Element free Galerkin method has been applied as a numerical tool. Thermal conductivities of nanotube and polymer matrix are assumed to vary quadratically with temperature. Picard and quasi-linearization schemes have been utilized to obtain the solution of a system of nonlinear equations. Cylindrical representative volume element has been used to evaluate the thermal properties of nano-composites. Present simulations show that the temperature dependent matrix thermal conductivity has a significant effect on the equivalent thermal conductivity of the composite, whereas temperature dependent nanotube thermal conductivity has a small effect on the equivalent thermal conductivity of the composite. The results obtained by Picard method have been found almost similar with those obtained by quasi-linearization approach.     

Vortex-induced oscillations at low Reynolds numbers: Hysteresis and vortex-shedding modes

Results are presented for the numerical simulation of vortex-induced vibrations (VIVs) of a cylinder at low Reynolds numbers (Re). A stabilized space–time finite-element formulation is utilized to solve the incompressible flow equations in primitive variables. The cylinder, of low nondimensional mass (m^*=10), is free to vibrate in, both, the transverse and in-line directions. To investigate the effect of Re and reduced natural frequency, F_n, two sets of computations are carried out. In the first set of computations the Reynolds number is fixed (=100) and the reduced velocity (U^*=1/F_n) is varied. Hysteresis, in the response of the cylinder, is observed at the low- as well as high-end of the range of reduced velocity for synchronization/lock-in. In the second set of computations, the effect of Reynolds number (50Re500) is investigated for a fixed reduced velocity (U^*=4.92). The effect of the Reynolds number is found to be very significant for VIVs. While the vortex-shedding mode at low Re is 2S (two single vortices shed per cycle), at Re300 and larger, the P+S mode of vortex shedding (a single vortex and one pair of counter-rotating vortices are released in each cycle of shedding) is observed. This is the first time that the P+S mode has been observed for a cylinder undergoing free vibrations. This change of vortex-shedding mode is hysteretic in nature and results in a very large increase in the amplitude of in-line oscillations. Since the flow ceases to remain two-dimensional beyond Re200, it remains to be seen whether the P+S mode of shedding can actually be observed in reality for free vibrations.     

Colloidal micelles of block copolymers as nanoreactors,templates for gold nanoparticles,and vehicles for biomedical applications

Target drug delivery methodology is becoming increasingly important to overcome the shortcomings of conventional drug delivery absorption method. It improves the action time with uniform distribution and poses minimum side effects, but is usually difficult to design to achieve the desire results. Economically favorable, environment friendly, multifunctional, and easy to design, hybrid nanomaterials have demonstrated their enormous potential as target drug delivery vehicles. A combination of both micelles and nanoparticles makes them fine target delivery vehicles in a variety of biological applications where precision is primarily required to achieve the desired results as in the case of cytotoxicity of cancer cells, chemotherapy, and computed tomography guided radiation therapy.     

Microbial synthesis of gold nanoparticles: Current status and future prospects

Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized.