Highlights • The peristaltic flow of couple stress fluid in an asymmetric channel through porous medium with heat transfer is studied. • The effects of slip and convective conditions are also ...considered. • Six types of different wave forms are considered for the analysis. • The effects of different flow parameters are discussed through graphs. • The comparison is made for Newtonian fluid and couple stress fluid models.
This article presents the effect of polyaniline (PANI) embedded copper cobaltite (CuCo2O4) as an electrode material for high performance supercapacitor application. The composite of PANI-CuCo2O4 was ...prepared via blending process. The formation of PANI-CuCo2O4 composite was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The surface morphologies showed that the spinel structure of CuCo2O4 (average particle size of 30nm) was well distributed on PANI matrix, suggest the effective intercalation of CuCo2O4 with PANI matrix. The electrochemical properties of CuCo2O4, PANI and PANI-CuCo2O4 composite were investigated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1M of KOH as an aqueous electrolyte. The PANI-CuCo2O4 composite showed the improved specific capacitance of 403C/g than that of pure CuCo2O4 and PANI.The enhanced electrochemical performance was obtained due to the augmentation of redox active sites and synergetic effect between PANI and CuCo2O4 nanoparticles. Additionally, the fabricated (activated carbon (AC)/PANI-CuCo2O4) asymmetric supercapacitor device can be cycled reversibly at a cell voltage of 1.5V, which exhibited excellent electrochemical performances with an energy density of 76Wh/kg and a power density of 599W/kg. It also presented a superior life cycle with 94% capacitance retention after 3000 cycles.
In the present review, we focused on the fundamental concepts of hydrogels—classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. ...Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.
•Excellent anti-corrosive properties of grapheme.•Pure graphene coatings and graphene composite coatings were used as anti-corrosive.•Anti-corrosion mechanism, optimization measures, and corrosion ...resistance of grapheme.•Explanation on its existing problems, challenges, and future research directions have been highlighted.
In various academic and industrial interests, graphene has achieved remarkable attention mainly by its distinctive chemical, mechanical, thermal, electrical and excellent anti-corrosion properties respectively, whereby the previous and ongoing researches have shown positive outcomes and its respective results achieved were at a satisfactory level. Over the last few years, the scope of the research on the applications of graphene based anti-corrosion has been intensely broadened and consists of two components, firstly pure graphene coatings and secondly graphene composite coatings. In the formulation of polymeric coatings, due to graphene and its derivatives having extraordinary lamellar structure, this material is highly suitable as anti-corrosive additives. Graphene creates pathways that are highly tortuous, thereby preventing the water and oxygen molecules to be diffused to the metal-based surface of materials, resulting in the protection of metal from oxidation and corrosion. Therefore, comprehensively reviewed in this article is the graphene-based coatings applications to metal anti-corrosion. First, the basic fundamentals of anti-corrosive coating technology will be discussed followed by and the current progress. Second, in detail, the preparation of graphene followed by pure graphene coatings methods respectively are illustrated. Third, the pure graphene coating in terms of corrosion resistance will be discussed, followed by detailed explanation on its existing problems and optimization respectively. Next, associated with graphene-based organic coatings, the graphene and graphene oxide dispersion and modification will be discussed, followed by the mechanism of barrier properties of graphene as well as the influence of the electrical conductivity. The anti-corrosion mechanism, optimization measures, corrosion resistance, and existing problems are summarized for the composite coatings fabricated using graphene. The challenges and future developments of anticorrosive graphene coatings are finally discussed and proposed, and their potential applications are discussed.
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•Co3O4 nanograin-decorated rGO composite was fabricated via hydrothermal route.•rGO-Co3O4 nanograin composite was used for modification of electrode.•rGO-Co3O4 nanograins showed ...excellent catalytic performance towards dopamine detection.•rGO-Co3O4 nanocomposite selectively detected dopamine in the presence of interfering species.
A sensitive and selective detection of dopamine (DA) by a sensor based on cobalt oxide (Co3O4) nanograin-decorated reduced graphene oxide (rGO) composite modified glassy carbon electrode (GCE) is reported. The rGO-Co3O4 nanograin composites are synthesized by a facile hydrothermal route and optimized by varying the contents of rGO (5.7, 7.4, 9.1 and 10.7wt%, denoted as C1, C2, C3 and C4 respectively). The crystallinity of the composite is examined by X-ray diffraction (XRD). Raman spectrum revealed the successful reduction of graphene oxide (GO) into rGO. The surface morphology through field emission scanning electron microscopy (FESEM) revealed that the granular-shaped Co3O4 are decorated on rGO matrix with an average particle size of∼35nm. For electrochemical oxidation of DA, glassy carbon electrode (GCE) is modified with nanocomposites. Cyclic voltammetric results show that C3 modified GCE exhibit enhanced electrocatalytic performance in terms of oxidation potential and peak current in comparison to those of bare GCE, Co3O4 nanograins, C1, C2 and C4 modified GCE. The choronoamperometric studies indicate that C3 modified GCE exhibit a low detection limit of (S/N=3) 0.277μM in the linear range of 1–30μM. In addition, C3 demonstrates good selectivity towards the detection of DA in the presence of a 100-fold higher concentration of ascorbic acid, glucose and uric acid as the interfering species. The electrochemical sensing studies suggest that 3D rGO-Co3O4 nanograins endow excellent catalytic activity, high selectivity and sensitivity towards DA.
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•Nickel oxide with different particle sizes are developed by a facile process.•The smaller particle size of 6nm with face centered cubic structure was observed.•CV and EIS study shows ...the pseudocapacitive behavior of NiO nanostructures.•NiO with smaller particle size exhibited enhanced specific capacitance.
In this work, we demonstrate the influence of nickel oxides with divergent particle sizes as the working electrodes for supercapacitor application. The nanostructured nickel oxide (NiO) is synthesized via facile sonochemical method, followed by calcination process. The crystallinity and surface purity of prepared samples are clearly examined by X-ray diffraction and Raman analysis. NiO crystallinity is significantly increased with increasing calcination temperatures. The surface analysis confirmed that the calcination at 250°C exhibited nanoclutser like NiO with average particle size of ∼6nm. While increasing the calcination temperature beyond 250°C, hexagonal shaped NiO is observed with enhanced particle sizes. The electrochemical performance confirmed the good redox behavior of NiO electrodes. Moreover, NiO with average particle size of ∼6nm exhibited high specific capacitance of 449F/g at a scan rate of 5mV/s compared to other samples with particle sizes of ∼21nm (323F/g) and ∼41nm (63F/g). This is due to the good ion transfer mechanism and effective electrochemical utilization of the working electrode.
Cancer is a rapidly growing disease and the second most leading cause of death worldwide. Breast, colon, lung, and prostate cancer are the most diagnosed types of cancer among the majority of the ...population. The prevalence of these cancers is increasing rapidly due to the lack of effective drugs. The search for anti-cancer bioactive components from natural plant sources is gaining immense significance. The aim of the paper is to introduce the readers about the in vitro and in vivo biochemical mechanisms of phenolic acids and flavonoids in these four types of cancers.
A literature search was carried out in databases, including Scopus, SciFinder, Springer, Science direct and Google. The main keywords used were fruits & vegetables, phenolic acids, flavonoids, anticancer, bioavailability, etc. The data obtained were integrated and analyzed.
The study revealed the potential molecular mechanisms of phenolic acids and flavonoids, which include the induction of apoptosis, inhibition of cell proliferation, cell-cycle arrest, induction of Poly ADP ribose polymerase cleavage, downregulation of Matrix metalloproteinases-2 and Matrix metalloproteinases-9 activities, decreased levels of B-cell lymphoma-2, etc. Promising effects of phenolic acids and flavonoids have been observed against breast, colon, lung and prostate cancers.
The in vitro and in vivo anti-cancer mechanisms of phenolic acids and flavonoids have been revealed in this study. With the knowledge of specific molecular targets and the structural-functional relationship of bioactive compounds, the current review will open a new gateway for the scientific community and provide them a viable option to exploit more of these compounds for the development of novel and efficacious anticancer compounds.
In the rapidly growing global energy consumption, diesel engines play the key role. Usage of diesel fuel contributes to harmful air pollution exhausted from combustion chamber. To overcome these ...serious issues, the biodiesel extracted from many feedstocks have been studied and implemented for the past few decades. The combustion characteristics of diesel are not same as the biodiesel blends due to the discrepancy in physio-chemical properties of biodiesel. Enormous studies have been focused on inadequate combustion profiles of biodiesel in compression ignition engines. This review paper analyzes the previous researches concerning the consequences of proposed effective strategies including the variation in engine operating parameters like fuel injection timing and injection pressure for enhancing combustion characteristics of biodiesel implementation. This study focuses its light on the advancement and retardation methods of injection timing and injection pressure to treat the engine combustion indicators such as in-cylinder pressure, peak cylinder pressure, heat release rate, ignition delay period and combustion duration, finally a comparative evaluation has been developed and the relevant reasons for the variation of combustion characteristics have been conversed. The review concludes that the advancement in injection timing and higher injection pressure are best in amplifying the combustion phenomena of biodiesel fuelling.
In this article, we have presented the exact solutions of the Couette, Poiseuille and generalized Couette flows of an incompressible magnetohydrodynamic Jeffrey fluid between parallel plates through ...homogeneous porous medium. The effects of slip boundary conditions and heat transfer are considered. Viscous dissipation, radiation and Joule heating are also considered in the energy equation. The governing equations of the Jeffrey fluid flow are modeled in Cartesian coordinate system. Analytical solutions for the velocity and temperature profiles are obtained for all mentioned cases. The influences of the sundry parameters on the velocity and temperature profiles are studied and the results are presented through graphs. It is noted that, with increase of slip parameter and pressure gradient increases the velocity. Temperature behaves as a decreasing function due to the impact of Hartmann number, non-Newtonian parameter and slip parameter in all noted problems.
There has been significant progress in the last few decades in addressing the biomedical applications of polymer hydrogels. Particularly, stimuli responsive hydrogels have been inspected as elegant ...drug delivery systems capable to deliver at the appropriate site of action within the specific time. The present work describes the synthesis of pH responsive semi-interpenetrating network (semi-IPN) hydrogels of N-succinyl-chitosan (NSC) via Schiff base mechanism using glutaraldehyde as a crosslinking agent and Poly (acrylamide-co-acrylic acid)(Poly (AAm-co-AA)) was embedded within the N-succinyl chitosan network. The physico-chemical interactions were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscope (FESEM). The synthesized hydrogels constitute porous structure. The swelling ability was analyzed in physiological mediums of pH 7.4 and pH 1.2 at 37°C. Swelling properties of formulations with various amounts of NSC/ Poly (AAm-co-AA) and crosslinking agent at pH 7.4 and pH 1.2 were investigated. Hydrogels showed higher swelling ratios at pH 7.4 while lower at pH 1.2. Swelling kinetics and diffusion parameters were also determined. Drug loading, encapsulation efficiency, and in vitro release of 5-fluorouracil (5-FU) from the synthesized hydrogels were observed. In vitro release profile revealed the significant influence of pH, amount of NSC, Poly (AAm-co-AA), and crosslinking agent on the release of 5-FU. Accordingly, rapid and large release of drug was observed at pH 7.4 than at pH 1.2. The maximum encapsulation efficiency and release of 5-FU from SP2 were found to be 72.45% and 85.99%, respectively. Kinetics of drug release suggested controlled release mechanism of 5-FU is according to trend of non-Fickian. From the above results, it can be concluded that the synthesized hydrogels have capability to adapt their potential exploitation as targeted oral drug delivery carriers.
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