Optical properties of sub-surface silver nanoparticulate films on 8 MeV electron beam irradiated polymer blends

Results of the investigations carried out on the optical properties of silver nanoparticulate films deposited on the electron beam irradiated blends of polystyrene (PS) and poly(4-vinylpyridine) (P4VP) are reported. Sub-surface silver particulate films are deposited at a constant deposition rate of 0.4 nm/s on irradiated blends held at 455 K in a vacuum of 8 × 10^?6 torr. The optical absorption studies indicate that the morphology of the nanoparticulate films can be tuned by electron beam irradiation of polymer blends. The change observed due to irradiation is attributed to the formation of free radicals, thereby altering the polymer–metal interaction. A shift in the plasmon resonance peak towards longer wavelengths is observed for 50 nm thick silver particulate films deposited on softened 8 MeV electron irradiated P4VP as compared to unirradiated P4VP. The shift is more in the case of P4VP than for PS, possibly due to the combined effect of free radicals produced by irradiation and the lone pair of electrons present in P4VP in enhancing the metal–polymer interaction. The saturation of free radicals takes place in P4VP at doses higher than 25 kGy. Further, the results also indicate that the free radical creation due to irradiation is more in PS than in P4VP, as the saturation takes place at lower doses in a PS/P4VP blend as compared to P4VP and in a blend with higher PS content. X-ray diffraction studies on silver films deposited on unirradiated and irradiated, softened polystyrene substrates do not show any significant change due to irradiation.     

Ageing and field effect studies on discontinuous silver films at near liquid nitrogen temperatures

The post deposition resistance changes in discontinuous silver films deposited in a vacuum of 2 × 10^–6 torr on glass substrates maintained at near liquid nitrogen temperatures have been studied. Reduced agglomeration rates in comparison with films studied at room temperature were obtained, supporting the thermally assisted mobility coalescence model explaining the post deposition resistance increase. The non-linearI-V characteristics of one of the films followed by observations of resistance changes before and after field effect measurements on the other films have been explained as arising due to field-induced structural changes. The investigations of the variation of film resistance with temperature revealed a transition temperature. A fall in resistance with increasing temperature below the transition temperature has been explained by an increase in the number of thermally charged islands. The increase in resistance with temperature above the transition temperature is due to an increase in the thermally assisted mobility coalescence.     

Simple HPLC Method for Resolution of Curcuminoids with Antioxidant Potential

ABSTRACT:  Development of methodology for qualitative analysis and quantitative separation of individual curcuminoids in curcumin removed turmeric oleoresin (CRTO) and study of antioxidant activity of individual curcuminoids have been achieved in the present study. A simple HPLC protocol was outlined for optimal resolution of curcuminoids (I), (II), and (III) on an Exil-NH₂ column using isocratic elution with a mixture of isopropanol and water. CRTO is shown to be good source for the compounds II and III, as they are in an enriched form. The optimum resolution of the curcumin and its analogs in the present method developed, affords a facile method for estimation of individual curcuminoids in turmeric samples, which is an improvement over the standard AOAC method which estimates only total curcuminoids. The free radical scavenging capacity of pure curcuminoids I, II, and III, as determined by DPPH method at 100 ppm concentration was 88%, 80%, and 68% with IC₅₀ values being 56, 62, and 73 ppm, respectively. Their antioxidant potential could render them useful as important nutraceuticals or functional food ingredients.     

Impact of homogeneous‐heterogeneous reactions in a hybrid nanoliquid flow due to porous medium

Chemical responses are investigated as a piece of the modern applications like hydrometallurgical industry, food processing, and polymer production. Numerous chemical responding structures consolidate homogeneous and heterogeneous response and it is especially eccentric. Hence, this paper explains how the hybrid nanoliquid flow is handy in accelerate the thermochemical possessions of the base fluid in existence of homogeneous‐heterogeneous reactions. Here, three different types of hybrid nanoliquid used are copper‐Al₂O ₃/water, silver‐Al ₂O ₃/water, and gold‐Al ₂O ₃/water. Outcoming differential systems are resolved numerically by adopting fourth‐order and fifth‐order Runge‐Kutta‐Fehlberg method. To get better view of the topic, the flow field, temperature behavior, and concentration curves are investigated for particular estimations of critical elements. The results predict that gold‐Al ₂O ₃/water nanoliquid has good impact of heat rate coefficient and further porosity parameter decelerates the velocity and accelerates the temperature of the hybrid nanofluid.     

Unifying Energetic Disorder from Charge Transport and Band Bending in Organic Semiconductors

Characterizing the density of states (DOS) width accurately is critical in understanding the charge‐transport properties of organic semiconducting materials as broader DOS distributions lead to an inferior transport. From a morphological standpoint, the relative densities of ordered and disordered regions are known to affect charge‐transport properties in films; however, a comparison between molecular structures showing quantifiable ordered and disordered regions at an atomic level and its impact on DOS widths and charge‐transport properties has yet to be made. In this work, for the first time, the DOS distribution widths of two model conjugated polymer systems are characterized using three different techniques. A quantitative correlation between energetic disorder from band‐bending measurements and charge transport is established, providing direct experimental evidence that charge‐carrier mobility in disordered materials is compromised due to the relaxation of carriers into the tail states of the DOS. Distinction and quantification of ordered and disordered regions of thin films at an atomic level is achieved using solid‐state NMR spectroscopy. An ability to compare solid‐state film morphologies of organic semiconducting polymers to energetic disorder, and in turn charge transport, can provide useful guidelines for applications of organic conjugated polymers in pertinent devices.     

Oxidative decolorisation of Eriochrome Black T with Chloramine‐T: kinetic,mechanistic, and spectrophotometric approaches

The kinetics and mechanism of oxidative decolorisation of Eriochrome Black T (EBT) with sodium N‐chloro‐p‐toluenesulfonamide or Chloramine‐T (CAT), catalysed by osmium tetroxide [Os(VIII)] in alkaline medium and uncatalysed in acid medium, have been spectrophotometrically investigated at 303 K. The reaction exhibited a first‐order dependence of rate on [CAT]₀ and [EBT]₀ in both media, and also with respect to [H⁺]. The order with respect to [OH^‐] and [Os(VIII)] was fractional. Activation parameters were deduced. It was observed that the uncatalysed decolorisation reaction was ca. eightfold faster in acid medium in comparison with alkaline medium, while the Os(VIII)‐catalysed reaction was ca. sevenfold faster than the uncatalysed reaction. Mechanisms and rate laws were determined. The chemical oxygen demand of Eriochrome Black T dye was also determined. Importantly, the developed oxidative decolorisation method is simple, efficient, inexpensive, requires less time, and is environmentally benign. Hence, it can be adapted for treating Eriochrome Black T present in industrial and laboratory wastewater.     

Cattaneo–Christov heat flux model for nanofluid flow over a curved stretching sheet: An application of Stefan blowing

The present work investigates the thermophoresis and Brownian motion effects in nanofluid flow over a curved stretching sheet (CSS). Also, the Cattaneo–Christov heat flux and Stefan blowing (SB) conditions are considered for studying heat and mass transport characteristics. The present work's novelty is associated with considerations of convective boundary and SB conditions in nanomaterial flow over a CSS. The coupled partial differential equations are changed to ordinary differential equations by employing suitable similarity variables, and the resultant model is numerically handled using Runge–Kutta–Fehlberg's fourth fifth-order method with the shooting scheme. The stimulation of the involved parameters/numbers on the flow, mass, and heat fields is broadly deliberated using suitable graphs. The present analysis's significant relevant outcomes are that the inclination in thermophoresis and Brownian motion parameters increases the heat transfer. The inclined values of the Brownian motion parameter decay the mass transfer. Furthermore, the increased values of both Schmidt number and SB parameter drop the mass transport. The increased values of the Brownian motion parameter and Schmidt number decays the rate of mass transference.     

Impact of bioconvection on the free stream flow of a pseudoplastic nanofluid past a rotating cone

In the current work, the repercussions of Brownian motion and thermophoresis on the three-dimensional free stream flow of tangent hyperbolic (pseudoplastic) nanofluid past a rotating cone are explored. The tangent hyperbolic model expresses the characteristics of a shear-thinning nanofluid. Furthermore, oxytactic microorganisms were used as mixers to actively stabilize the nanoparticles. The movement of these microorganisms within the nanofluid gives rise to a major phenomenon termed bioconvection. The flow of nanofluid past a rotating cone finds applications in the field of nuclear reactors, biomedical applications, solar power collectors, steam generators, and so on. The mathematical model is designed using Buongiorno's model that describes the two major slip mechanisms experienced by the nanoparticles moving within a fluid namely thermophoretic force and Brownian motion. The model thus formed is nondimensionalized using the apt similarity transformation. The resulting system is solved by the $\mathrm{RKF}-45$ technique by adapting the shooting method. The velocity, temperature, concentration, and motile density profiles are graphically interpreted for different flow parameters involved in the study. It was observed that thermophoresis reduces concentration and enhances the temperature whereas Brownian motion enhanced both temperature and concentration profiles. Also, the increase in the mixed convection parameter effectively decreased the temperature of the nanofluid.     

Multi-Band Heterogeneous Wireless Network Architecture for Industrial Automation: A Techno-Economic Analysis

Wireless Personal Communications - To attain automation across different applications, industries are beginning to leverage advancements in wireless communication technologies. A...