A study of heat and mass transfer of Non-Newtonian fluid with surface chemical reaction

Considering the significance of non-Newtonian fluid usage in manufacturing such as molten plastics, polymeric materials, pulps, and so on, significant efforts have been made to investigate the phenomenon of non-Newtonian fluids. In this article the influences of heat and mass transfer on non-Newtonian Walter's B fluid flow over uppermost catalytic surface of a paraboloid is encountered. An elasticity of the fluid layer is considered in the freestream together with heat source/sink and has the tendency to cause heat flow in the fluid saturated domain. The flow problem of two-dimensional Walter's B fluid is represented using Law of conservation of mass, momentum, heat, and concentration along with thermal and solutal chemical reactive boundary conditions. The governing equations are non-linear partial differential equation and are non-dimensionalized by employing stream function and similarity transformation. The final dimensionless equations yielded are coupled non-linear ordinary differential equations. Furthermore, shooting technique along with RK-4th order method is used to get the numerical results. Graphs and tables are modeled by using MATLAB software to check the effects of Walter's B parameter, Chemical reaction parameter and Thickness parameter on temperature, velocity, and concentration profiles. Tabular analysis shows the results of some physical parameters like skin friction coefficient, Nusselt number and Sherwood number due to the variation of Walter's B parameter, thickness parameter and chemical reactive parameter.     

Phyto-Extract-Mediated Synthesis of Silver Nanoparticles Using Aqueous Extract of Sanvitalia procumbens,and Characterization,Optimization and Photocatalytic Degradation of Azo Dyes Orange G and Direct Blue-15

Green synthesis of silver nanoparticles (AgNPs) employing an aqueous plant extract has emerged as a viable eco-friendly method. The aim of the study was to synthesize AgNPs by using plant extract of Sanvitalia procumbens (creeping zinnia) in which the phytochemicals present in plant extract act as a stabilizing and reducing agent. For the stability of the synthesized AgNPs, different parameters like AgNO₃ concentration, volume ratios of AgNO₃, temperature, pH, and contact time were studied. Further, AgNPs were characterized by UV–visible spectroscopy, FT-IR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray Spectrometer) analysis. FT-IR analysis showed that the plant extract contained essential functional groups like O–H stretching of carboxylic acid, N–H stretching of secondary amides, and C–N stretching of aromatic amines, and C–O indicates the vibration of alcohol, ester, and carboxylic acid that facilitated in the green synthesis of AgNPs. The crystalline nature of synthesized AgNPs was confirmed by XRD, while the elemental composition of AgNPs was detected by energy dispersive X-ray analysis (EDX). SEM studies showed the mean particle diameter of silver nanoparticles. The synthesized AgNPs were used for photocatalytic degradation of Orange G and Direct blue-15 (OG and DB-15), which were analyzed by UV-visible spectroscopy. Maximum degradation percentage of OG and DB-15 azo dyes was observed, without any significant silver leaching, thereby signifying notable photocatalytic properties of AgNPs.     

Antibacterial Activity of Light-Activated Silicone Containing Methylene Blue and Gold Nanoparticles of Different Sizes

Methylene Blue and methylene blue-gold nanoparticle mixtures were encapsulated in a silicone polymer using a swell-encapsulation-shrink technique. The antibacterial properties of the materials, when tested against Escherichia coli and Staphylococcus epidermidis, and exposed to laser light (660 nm), were significantly affected by both the presence and size of Au nanoparticles. Bacterial inactivation data were analysed using the Weibull inactivation model. For both E. coli and S. epidermidis the value of the parameter, indicating the time required to achieve the first log₁₀ reduction in the viable count, decreased when Au nanoparticles of ca 2 nm diameter were present. Larger Au nanoparticles (diameters of 5 and 20 nm) in combination with methylene blue were also embedded in silicone. The values of these materials increased with nanoparticle diameter, indicating a reduction in antibacterial activity. In all cases E. coli had higher values than S. epidermidis.     

Lagrangian Curves on Spectral Curves of Monopoles

We study Lagrangian points on smooth holomorphic curves in ${\rm T}{\mathbb P}^1$ equipped with a natural neutral Kähler structure, and prove that they must form real curves. By virtue of the identification of ${\rm T}{\mathbb P}^1$ with the space ${\mathbb L}({\mathbb E}^3)$ of oriented affine lines in Euclidean 3-space ${\mathbb E}^3$ , these Lagrangian curves give rise to ruled surfaces in ${\mathbb E}^3$ , which we prove have zero Gauss curvature. Each ruled surface is shown to be the tangent lines to a curve in ${\mathbb E}^3$ , called the edge of regression of the ruled surface. We give an alternative characterization of these curves as the points in ${\mathbb E}^3$ where the number of oriented lines in the complex curve Σ that pass through the point is less than the degree of Σ. We then apply these results to the spectral curves of certain monopoles and construct the ruled surfaces and edges of regression generated by the Lagrangian curves.     

Comparison of the photochemistry of organometallic N-heterocyclic carbene and phosphine complexes of manganese

Time-resolved IR (TRIR) studies on (η(5)-C(5)H(4)Me)Mn(L)(CO) (L = 1,3-diethyl-4,5-dimethylimidazol-2-ylidene, PPh(3)) indicate that the rate of reaction with CO is ca. 10(2) slower for the N-heterocyclic carbene intermediate, which DFT calculations suggest is due to the presence of a strong MnH-C agostic bond. The reactivity of these intermediates in alkane solvents is governed by such interactions rather than solvent coordination to the unsaturated metal centre.     

A mild and facile method for one pot synthesis of 2,5-di-substituted 1,3,4-oxadiazoles at room temperature

2,5-Di-substituted 1,3,4-oxadiazoles 3a-n have been synthesized as a one pot procedure from the reaction of acid hydrazide 1, acyl halides 2 and phosphorus pentoxide in acetonitrile at room temperature. High yield, short reaction time （10-15 min）, mild condition, and easy work-up are advantages of this methodology.