•Polyaniline was synthesized by inverse emulsion polymerization in the presence of various concentration of polyvinyl alcohol.•Increased thermal stability of PANI/PVA as compared to ...PANI.•Incorporation of PVA increased conductivity and crystallinity of PANI.•The SEM of PANI/PVA composites show irregular shaped particles with variable size.
The properties of conducting polymers (CPs) such as polyaniline (PANI) and its derivatives can be modified, improved and even enhanced by making composites with materials which can change the extent and level of doping in the CPs. This paper reports on the synthesis of PANI in the presence of various concentration of polyvinyl alcohol by inverse emulsion polymerization. The as synthesized PANI and PANI/PVA were characterized with UV/VIS, FTIR, XRD, TGA, SEM, conductivity and electrochemical measurements. The results demonstrated the formation of polyaniline doped with polyvinyl alcohol showing high thermal stability and improved room temperature conductivity. The synthesized composites were found to be soluble in common organic solvents such as N-methylpyrolidinone (NMP), Chloroform, 2:1 mixture of toluene and 2-proanol, 1:1 mixture of chloroform and toluene and 2:1 mixture of toluene and methanol. Cyclic voltammetric studies showed good redox properties of synthesized PANI and PANI/PVA.
•Poly(o-toluidine) synthesized by inverse emulsion polymerization.•Completely soluble in several organic solvents.•Conductance as of electrosynthesized POT, film stable in air up to 513°C.•Highly ...efficient corrosion protection on steel with 77% protection efficiency.
We report on the synthesis of poly(o-toluidine) (POT), a methyl-substituted derivative of PANI, by inverse emulsion polymerization. A mixture of 2-butanol and chloroform was used as dispersion medium; benzoyl peroxide as oxidant, while dodecylbenzenesulfonic acid (DBSA) was used both as dopant and as surfactant. POT was collected in its salt form and was found to be completely soluble in various organic solvents (so far highest number of solvents) such as DMSO, chloroform, toluene, THF, acetonitrile and ethanol. The synthesized polymer was characterized by cyclic voltammetry, in situ UV–Vis spectroelectrochemistry, viscosity and in situ conductance measurements, FTIR and TGA. Conductance measurements show that POT has high conductance comparable with that of electrochemically synthesized POT. The POT film dip-coated on a gold electrode was highly stable in air; no appreciable decrease in the electrochemical activity of the film occurred even when left open for 14 days in air. Thermal analysis reveals a very good thermal stability up to 513°C. Potentiodynamic polarization measurements show that POT acts as a highly efficient corrosion protection layer on steel with 77% protection efficiency.
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•DFT and TD-DFT were employed for sensing properties of POAP and POAP+ toward NH3.•Split valence basis set (6-31G*) is used for the simulation of all geometric and electronic ...properties.•Greater interaction with NH3 was observed for the NH site of POAP as compared to O site.•The study suggests better sensing properties of POAP for NH3 gas as compared to polyaniline.
The response of poly(o-aminophenol) (POAP) both in doped and undoped forms toward NH3 gas was investigated on the basis of density functional theory (DFT) at B3LYP and UB3LYP/6-31G* level of theory. POAP is unique due to the presence of two potential interactive sites, i.e., NH and O. The sensing ability of both of these interactive sites was investigated. Change in geometric parameters, and interaction energy analysis provide an effective evidence for the sensing ability of POAP for NH3 gas. Further support to the sensing response was obtained by natural bond orbital (NBO) and Mulliken charge analysis. Density of state spectra also show the interaction of NH3 with POAP and provide an understanding of the response mechanism of POAP toward NH3. Greater interaction was observed for the NH site of POAP as compared to O site, illustrating that NH site is the actual interactive site of POAP in both doped/undoped forms. The response became more sophisticated in the doped form of POAP.
Carbon emission from burning fossil fuels associated with anthropogenic activities has caused severe environmental issues and extreme weather events linked to human-induced climate change. In recent ...years, scientists have been focusing on renewable energy resources for environmental remediation and green production to mitigate the harmful effects of a climate crisis. Electrochemical water splitting is emerging to produce green hydrogen from water electrolysis, which is considered a major fuel source for the future. In efforts to replace precious Pt-based electrocatalysts, nickel (Ni) metal-based materials have gained huge attraction due to their abundant availability, low price, and high activity. Herein, we summarized significant strategies and highlighted recent advances in electrochemical hydrogen generation from water splitting over Ni metal-based electrocatalysts, mainly categorized by type of Ni-based catalysts. The hydrogen evolution reaction (HER) insights have been analyzed and discussed via modern techniques, and then the correlation between catalytic performances and the tailor of electrocatalysts has been proposed. The conclusions and prospects with discussions of recent improvements, known technological hurdles, and promising opportunities for future discovery are presented.
Graphical Abstract
The explainable human–computer interaction (HCI) is about designing approaches capable of using cognitive characteristics like humans. One such characteristic is human vision and its accuracy. The ...accuracy measures the trust in that system. Therefore, improving accuracy in the authorization with identification process is a primary concern for a visual-based explainable human–computer interaction system. In this article, we propose a three-way decision based ensembled face recognition mechanism called E3FRM. The E3FRM uses a three-way approach to determine the match cases and the respective worth of the captured image with the match cases. Features are extracted using PCA/FLD, and the ensembled face recognition algorithms utilize the extracted features to process the image. Ensemble Face recognition approaches find the match cases based on a given threshold. Finally, the three-way decision model evaluates the suitability of the captured image for acceptance, rejection, or deferred cases with a dual verification mechanism. Experimental results on well-known eighteen datasets suggest improvements in commonly used metrics of F1, Accuracy and Recall by up to 0.8% to 12.8%, 1% to 9.6% and 1.2% to 13.9%, respectively, in comparison to the state-of-the-art methods available, including SPCA +, ML-EM, FLDA-SVD, DMMA, Fast-DMMA, LU, LPP, TDL, KCFT, RBF + DT, and NMF. Furthermore, the proposed approach is comparatively analyzed with ensembled face recognition methods that result in an outperformed F1, Accuracy and Recall by up to 1.1% to 10.3%, 0.1% to 7.3% and 0.9% to 10.5%, respectively. These results suggest that the proposed model may improve face recognition accuracy and the resulting trust in the machines.
A comparative discussion of the electrochemical and spectroelectrochemical properties of poly(
o-phenylenediamine) POPD, an aromatic diamine, is presented.
In situ conductance measurements show that ...POPD shows some conductance around the redox peak potentials, i.e.
=
−0.02
<
E
SCE
<
0.00
V.
In situ UV–vis and Raman spectroelectrochemical results suggest that radical cations of polyaniline (PANI)-like segments in POPD backbone might be responsible for imparting conductance to this otherwise nonconducting polymer (as commonly supposed in the literature). The presence of radical cations was confirmed by
in situ Raman spectra showing a band at 1390
cm
−1 characteristic of a C–N
+-stretching vibration having an intermediate single/double bond character and being coupled to quinoid rings/polaronic form of PANI segments in the polymer. Results also reveal that POPD shows a close correlation between its electrochemical and spectroelectrochemical properties in the range of −0.02
<
E
SCE
<
0.00
V, and provide support for the suggested presence of doped PANI-like segments in said potential range.
Concentration dependence of surface excess concentration of KBr solutions at different temperatures.
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► Determination of surface tension and density for 10 different salt solutions. ► ...Estimation of surface excess concentration, enthalpy, entropy of surface formation. ► Decrease in enthalpy of surface formation with concentration. ► Decrease in entropy of surface formation due to double layer formation.
Surface tensions of aqueous solutions of sodium salts of chloride, bromide and nitrate; potassium salts of chloride, bromide and nitrate; lithium chloride and potassium iodide has been determined experimentally at different concentrations and temperatures ranging from 0.10 to 2.00molkg−1 and 10–30°C, respectively. Concentration and temperature dependence of the surface tension of the selected salts has been studied for further estimation of surface excess concentration, enthalpy and entropy of surface formation. The results show that the surface excess concentration decreases linearly with concentration but remains almost constant with the variations of temperature. Similarly the enthalpy of surface formation was observed to decrease with concentration but remained almost constant with the change in temperature. The entropy of surface formation was found to decrease with concentration in most cases.
•We report preparation of Cu II chloride doped polyaniline (PANI-Cu).•Inverse emulsion polymerization route was employed for the synthesis.•TGA results show less thermal stability of PANI-Cu as ...compared to PANI.•PANI-Cu was relatively less crystalline as compared to PANI.
Polyaniline and its composites with Cu II chloride were synthesized by inverse emulsion polymerization. The synthesized composites were characterized with UV/vis, FT-IR, XRD and SEM. The results show the presence of polyaniline in the emeraldine base form doped with copper II chloride. The thermal properties of the composites were studied by carrying out TGA. The electrical transport properties were calculated from the conductivity measurement. The composites were found to be soluble in common organic solvents such as chloroform, NMP, DMSO, 1:2 mixture of 2-propanol and toluene and 1:2 mixture of 2-propanol and chloroform. Cyclic voltammetry was carried out to find out the redox properties of synthesized composites.
Maxillary canines are generally considered important both cosmetically and functionally. Most claims on the importance of maxillary canines, however, have been based on expert opinions and ...clinician-based studies. There are no scientific studies in the literature reporting on their cosmetic importance or how laypeople perceive a smile treated by maxillary canine extractions. Our objective was to investigate whether there is any difference in the perceptions of patients' smiles treated by extracting either maxillary canines or first premolars, as judged by orthodontists, dentists, and laypeople.
This retrospective study included 24 participants who had unilateral or bilateral extraction of maxillary permanent canines and fixed appliances in the maxillary and mandibular arches to comprehensively correct the malocclusion, selected from orthodontic patients treated at Chesterfield Royal Hospital NHS trust in the United Kingdom over the last 20 years. The control group of patients had extraction of maxillary first premolars followed by fixed appliances and finished to an extremely high standard judged by the requirement that they had been submitted for the Membership in Orthodontics examination. The finished Peer Assessment Rating scores for this group were less than 5. The end-of-treatment frontal extraoral smiling and frontal intraoral views were presented for both groups. The photographs were blinded for extraction choice and standardized for size and brightness using computer software (Adobe Photoshop CC version 14.0; Adobe Systems, San Jose, Calif). The work file was converted to an editable pdf file and e-mailed to the assessors. The assessor panel consisted of 30 members (10 orthodontists, 10 dentists, and 10 laypeople), who were purposely selected. The measures were rated on a 10-point Likert scale.
The attractiveness ratings were not statistically significantly different between the canine extraction and premolar extraction groups, with a mean difference of 0.33 (SD, 0.29) points. A 1-way repeated-measures analysis of variance to test the difference in scores among the laypeople, orthodontists, and dentists (n = 30) showed no statistically significant difference (Wilks lambda = 0.835; P = 0.138), and the Bonferroni test indicated that no pair-wise difference was statistically significant.
No statistically significant difference was found in the smile attractiveness between canine extraction and premolar extraction patients as assessed by general dentists, laypeople, and orthodontists. Further high-quality studies are required to evaluate the effect of canine extraction and premolar substitution on functional occlusion.
•Little evidence supports the cosmetic and functional importance of maxillary canines.•Raters found little difference in attractiveness between canine and premolar extractions.•Canine extraction should be a treatment option when it has other advantages.•Effect of canine extraction and premolar substitution on functional occlusion should be studied.
Image denoising is a vital pre-processing phase, used to refine the image quality and make it more informative. Many image-denoising algorithms have been proposed with their own pros and cons. This ...paper presents a comprehensive study of the median filter and its different variants to reduce or remove the impulse noise from gray scale images. These filters are compared with respect to their functionality, time complexity and relative performance. For performance evaluation of the existing algorithms, extensive MATLAB based simulations have been carried out on a set of images. For benchmarking the relative performance, we have used Peak Signal to Noise Ratio (PSNR), Root Mean Square Error (RMSE), Universal Image Quality Index (UQI), Structural Similarity Index (SSIM) and Edge-strength Similarity (ESSIM) as quality assessment metrics. The Extended median filter (EMF) and Modified BDND are best in terms of relative statistical ratios and pleasant visual results where IAMF is having the best time complexity among existing algorithms.
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