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Besse first conjectured that the solution of the critical point equation (CPE) must be Einstein. The CPE conjecture on some other types of Riemannian manifolds, for instance, odd-dimensional Riemannian manifolds has considered by many geometers. Hence, it deserves special attention to consider the CPE on a certain class of almost contact metric manifolds. In this direction, the authors considered CPE on almost f-cosymplectic manifolds.

The paper opted the tensor calculus on manifolds to find the solution of the CPE.

In this paper, in particular, the authors obtained that a connected f-cosymplectic manifold satisfying CPE with \lambda=\tilde{f} is Einstein. Next, the authors find that a three dimensional almost f-cosymplectic manifold satisfying the CPE is either Einstein or its scalar curvature vanishes identically if its Ricci tensor is pseudo anti‐commuting.

The paper proved that the CPE conjecture is true for almost f-cosymplectic manifolds.

The purpose of this paper is to investigate the inhibition effect of hydralazine hydrochloride as a corrosion inhibitor for mild steel in 1M HCl. The inhibition effect was studied at different temperatures, ranging from 303 to 333°K.

The inhibition efficiency of hydralazine hydrochloride was analyzed using weight loss, Tafel polarization, electrochemical impedance spectroscopy and surface morphology methods. The effect of temperature on the corrosion behavior of mild steel in 1M HCl was studied and discussed using an adsorption isotherm and activation parameters.

Weight loss, polarization and impedance showed that the inhibition efficiency increases with an increase in the concentration of hydralazine hydrochloride for mild steel in 1M HCl. The inhibitive action may be attributed to the adsorption of the inhibitor molecule on the active sites of the metal surface by the Langmuir adsorption isotherm. Polarization curves indicated that hydralazine hydrochloride acts as a mixed-type inhibitor. Scanning electron microscopy was performed on inhibited and uninhibited mild steel samples to characterize the surface. Thermodynamic parameter indicated that the adsorption of hydralazine hydrochloride is a spontaneous process and the adsorption occurs chemically.

The inhibition effect of hydralazine hydrochloride for mild steel has been investigated at different temperatures, ranging from 303 to 333°K. Hydralazine hydrochloride was a good inhibitor at a higher temperature.

Corrosion is a major concern for many industries that use metals as structural or functional materials, and the use of corrosion inhibitors is a widely accepted strategy to protect metals from deterioration in corrosive environments. Moreover, the toxic nature, non-biodegradability and price of most conventional corrosion inhibitors have encouraged the application of greener and more sustainable options, with natural and synthetic drugs being major actors. Hence, this paper aims to stress the capability of natural and synthetic drugs as manageable and sustainable, environmentally friendly solutions to the problem of metal corrosion.

In this review, the recent developments in the use of natural and synthetic drugs as corrosion inhibitors are explored in detail to highlight the key advancements and drawbacks towards the advantageous utilization of drugs as corrosion inhibitors.

Corrosion is a critical issue in numerous modern applications, and conventional strategies of corrosion inhibition include the use of toxic and environmentally harmful chemicals. As greener alternatives, natural compounds like plant extracts, essential oils and biopolymers, as well as synthetic drugs, are highlighted in this review. In addition, the advantages and disadvantages of these compounds, as well as their effectiveness in preventing corrosion, are discussed in the review.

This survey stresses on the most recent abilities of natural and synthetic drugs as viable and sustainable, environmentally friendly solutions to the problem of metal corrosion, thus expanding the general knowledge of green corrosion inhibitors.

This paper aims to synthesize nanostructured flower-like molybdenum disulphide (MoS₂) particles and evaluate their suitability to act as additives for lubricants.

A hydrothermal method without any surfactant successfully produced 250 nm mean diameter Nanostructured flower-like MoS₂ particles. The resulting product was then solvothermally treated with absolute ethanol producing lipophilic powder particles which after being dispersed in two different lubricants were tribologicaly characterized by using a pin-on-disk tribometer geometry with reciprocal movement under immersion.

The influence on the stability and the coefficient of friction of the nano-oils is shown to be strongly dependent on their molecular structure. After 1 h of tribological testing, a ramified polyolester oil with 1 Wt.% of MoS₂ nanoflowers did not show decrease in its average coefficient of friction, while an additive naphthenic oil with the same concentration of nanoparticles showed a decrease of 86 per cent.

In this paper, nanostructured flower-like MoS₂ synthesized by the hydrothermal method was dispersed in lubricating oils to study its stability and tribological properties. To ensure good stability of the nano-oils, the particles were solvothermally treated with absolute ethanol to dehydrate and lipophilize them. A ramified polyolester-based nano-oil with 1 Wt.% of MoS₂ nanoflowers showed no decrease in its steady state coefficient of friction, while a naphthenic-based nano-oil with the same concentration of nanoparticles presented a remarkable 86 per cent reduction.

The purpose of this paper is to study the corrosion inhibition performance of an eco-friendly drug clozapine on the corrosion of copper in 1.0 M nitric acid and 0.5 M sulfuric acid solutions.

The corrosion inhibition nature of inhibitor molecule was evaluated by weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization studies. An attempt was made to correlate the molecular properties of neutral and protonated forms of inhibitor molecule using quantum chemical calculations. The effect of temperature on the corrosion inhibition efficiency was also studied using electrochemical impedance spectroscopy. The potential of zero charge was determined to explain the mechanism of corrosion inhibition.

The studies on corrosion inhibition performance of clozapine showed that it has good corrosion inhibition efficiency on the corrosion of copper in 1.0 M nitric acid and 0.5 M sulfuric acid solutions. The adsorption of clozapine molecules onto the copper surface obeyed the Langmuir adsorption isotherm. The value of free energy of adsorption calculated is very close to −40 kJmol⁻¹, indicating that the adsorption is through electrostatic coulombic attraction and chemisorption. The decrease in the value of energy of activation with the addition of inhibitor also shows the chemisorption of the inhibitor on the metal surface. The potential of zero charge and quantum chemical studies confirmed that the protonated molecules also get involved in the corrosion inhibition process through physisorption.

The present work indicates that clozapine can act as a good corrosion inhibitor for the corrosion of copper in acid media.

This study aims to explore: the impact of customers' previous experience on their likelihood of using kiosks at quick service restaurants (QSRs); a mediating role of customer readiness (i.e. role clarity, ability, extrinsic motivation, intrinsic motivation) between customers' previous experience and their likelihood of using kiosks; and a moderating effect of gender in the relationships among customers' previous experience, readiness, and likelihood of using kiosks.

A total of 614 complete responses were obtained through an online survey. Structural equation modeling was developed and tested.

The results demonstrated that extrinsic motivation in using SSTs directly influenced the likelihood of using kiosks, and previous experience with SSTs indirectly influenced the likelihood of using kiosks through customer readiness in both male and female groups. This study also revealed that both male and female respondents who perceived their roles in using SST more clearly were more likely to use kiosks at QSRs. However, their perceived ability and levels of intrinsic motivations did not significantly influence the likelihood of using kiosks in both groups. Overall, gender did not play a significant moderating role in the relationships among experience, readiness, and likelihood of using kiosks at QSR.

Since very few studies have investigated the kiosks adoption at QSR settings, the findings and suggestions from this study will provide practical insight for QSR operators. Future research could attempt to draw a comprehensive kiosk acceptance model by incorporating the current study's framework with other demographic variables or other antecedent variables.

The purpose of this study was to investigate the performances of three inhibitors in controlling corrosion of local mild steel products in distilled water and a simulated salt solution.

Corrosion inhibition of mild steel was investigated using electrochemical techniques. Untreated and inhibitor treated specimens were fully immersed in two test solutions, distilled water and the simulated solution of 2.0 wt.% NaCl and 1.0 wt.% Na2SO₄.

During full immersion in the simulated salt solution, sodium dihydrogen orthophosphate was not effective at all, resulting in even higher corrosion rates than that of the untreated specimens. Sodium benzoate was effective for three days only. Dicyclohexylamine nitrite was the most effective of them all, keeping its effectiveness for as much as 20 days. When the specimens were immersed in distilled water, all three inhibitors were effective during the 60 days of immersion while dicyclohexylamine nitrite and sodium benzoate treated specimens performed better than those treated with sodium dihydrogen orthophosphate.

The objective of this research was to investigate the performances of three inhibitors – sodium dihydrogen orthophosphate (inorganic) at 10 mM concentration, dicyclohexylamine nitrite (organic) and sodium benzoate (organic) at 100 mM concentration – in controlling the corrosion of local mild steel products fully immersed in two test solutions, distilled water and the simulated salt solution. All three inhibitors are film forming and anodic type inhibitors. According to the authors' literature review, this study is original and will add value to the studies of inhibition of steel corrosion under similar environments.

Thin coatings are of great importance to minimize corrosion attack of steel in different environments. A review of recent work on electrodeposition and corrosion performance of Zn-Ni-based alloys for sacrificial corrosion protection of ferrous substrates is presented. The purpose of this study is to provide a systematic comparison of the corrosion resistances of Zn-Ni alloy coatings. The review contains key and outstanding comparisons of references for the period from 2007 to 2017. Binary and ternary Zn-Ni-based alloys were compared and contrasted to provide a good knowledge basis for selection of best coating system to steel substrates.

This article is a review article.

Zn-Ni-(X) alloys show great potential for replacing Cd metal in corrosion protection of steel substrates.

The research on plating of binary Zn-Ni alloys from aqueous electrolytes is now well advanced and these alloys show improved corrosion resistance compared to pure Zn. Pulse plated and compositionally modulated multilayer Zn-Ni alloy coatings showed enhanced corrosion properties compared to direct plated Zn-Ni coatings of similar composition.

The work on electrodeposition of Zn-Ni based alloys from ionic liquids is still scarce, yet these liquids show great promise in improving corrosion resistance and reducing coating thickness when compared to aqueous electrolytes. Advanced plating techniques in ionic liquids such as electromagnetic, compositionally modulated multilayer, pulse plating, ternary alloys and composites should be considered as these electrolytes avoid water chemistry and associated defects.

This paper aims to investigate the parametric study of addition of snail shell particles (SSp) and bath temperature on the properties of Zn-ZnO-SSp composites coating.

Bath temperatures of 60°C and 90°C and SSp of 0, 5, 10, 15, 20 and 25g were used in the electrodeposition. The microstructure, electrochemical, wear and hardness values of the coated samples were determined.

Highest coating thickness of 240 µm, 277 per cent improvement in hardness values, 66.67 per cent improvement of wear rate were obtained at bath temperature of 60oC and 15gSSp addition over that of the uncoated sample. There was improvement in corrosion resistance after composites coating. Maximum improvement in the properties was obtained at bath temperature of 60°C at 15gSSp addition.

It has been established in this work that bath treatment and SSps improved the properties of the developed coating.

In this study, electrochemical deposition method which have cheaper equipment than thermal spraying methods and is available for the production of composite coatings were used.

Composite coatings were electrodeposited from a Watts's bath solution in which the suspended Cr₃C₂-NiCr particles were dispersed in the bath solution during deposition. Potentiodynamic polarization and electrochemical impedance spectroscopy techniques have been used to evaluate the corrosion resistance of the composite coating in the 3.5 Wt.% NaCl solution.

It was found that the submicron Cr₃C₂-NiCr particles distributed uniformly in the coating and depend on the current density of deposition, different amount of particles can be incorporated in the coating. The results showed that the corrosion resistance of the Ni/ Cr₃C₂-NiCr composite coatings is more comparable to the pure nickel coating.

Production of Ni-base composite coating from an electrolytic bath containing Cr₃C₂-NiCr particles is possible via electrodeposition.