In situ fabrication of meso-tetrakis(4-sulfonatophenyl)porphyrin nanostructures with excitonic absorption on glass substrate

In this article, we report in situ fabrication of meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) nanostructures with excitonic absorption on glass substrate. The exposure of TPPS thin film coated on a glass plate to HCl vapor resulted in the formation of nanostructures of TPPS. The formed TPPS nanostructures on glass plate were characterized by UV-vis, steady state emission spectral techniques, atomic force microscopy, and high resolution transmission electron microscopy (HR-TEM). A new sharp and intense absorption band (excitonic band) at 490 nm was observed for TPPS nanostructures on glass plate. Protonation of tertiary nitrogen atoms of TPPS ring by HCl molecules leads to the formation of nanostructures of J-aggregates of TPPS on glass surface. The height of the TPPS nanostructures was found to be 50-170 nm with an average width of 100 nm. HR-TEM images showed that the formed TPPS J-aggregates consist of tiny nanorods. The size of the nanostructures was tuned successfully by varying the concentration of TPPS used for thin film preparation.     

Green synthesis of copper oxide nanoparticles and mosquito larvicidal activity against dengue,zika and chikungunya causing vector Aedes aegypti

In the present study, high purity copper oxide nanoparticles (NPs) were synthesised using Tridax procumbens leaf extract. Green syntheses of nano‐mosquitocides rely on plant compounds as reducing and stabilising agents. Copper oxide NPs were characterised using X‐ray diffraction (XRD) analysis, Fourier transform infrared (FT‐IR), Field‐emission scanning electron microscopy with energy dispersive spectroscopy, Ultraviolet–visible spectrophotometry and fluorescence spectroscopy. XRD studies of the NPs indicate crystalline nature which was perfectly matching with a monoclinic structure of bulk CuO with an average crystallite size of 16 nm. Formation of copper oxide NPs was confirmed by FT‐IR studies and photoluminescence spectra with emission peaks at 331, 411 and 433 nm were assigned to a near‐band‐edge emission band of CuO in the UV, violet and blue region. Gas chromatography–mass spectrometry studies inferred the phytochemical constituents of the leaf extract. Larvicidal activity of synthesised NPs using T. procumbens leaf extract was tested against Aedes aegypti species (dengue, chikungunya, zika and yellow fever transmit vector).Inspec keywords: photoluminescence, spectrophotometry, thermal analysis, chromatography, nanoparticles, antibacterial activity, field emission electron microscopy, microorganisms, wide band gap semiconductors, scanning electron microscopy, X‐ray diffraction, copper compounds, ultraviolet spectra, nanofabrication, X‐ray chemical analysis, crystallites, visible spectra, field emission scanning electron microscopy, nanobiotechnology, semiconductor materials, semiconductor growth, fluorescence, mass spectraOther keywords: energy dispersive spectroscopy, ultraviolet–visual spectrophotometry, fluorescence spectroscopy, chikungunya, green synthesis, mosquito larvicidal activity, zika, X‐ray diffraction analysis, field‐emission scanning electron microscopy, XRD, gas chromatography–mass spectrometry, copper oxide nanoparticles, dengue, tridax procumben leaf extract, nanomosquitocides, FTIR, monoclinic structure, crystallite size, photoluminescence spectra, near‐band‐edge emission band, phytochemical constituents, Aedes aegypti species, yellow fever transmit vector, CuO     

Effective removal of Cr(VI) and methyl orange from the aqueous environment using two-dimensional (2D) Ti3C2Tx MXene nanosheets

Industrial use of heavy metals and dyes critically depends on the effective handling of industrial effluents. Effective remediation of industrial effluents using various adsorbent materials has thus become critical. In this paper, we study two-dimensional MXenes as an adsorbent for removing Cr(VI) and methyl orange (MO) in waters. The physico-chemical performance of MXenes was studied using X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer?Emmett?Teller, scanning electron microscopy, high resolution-transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques. The adsorption system, including influence of contact time, pH of solutions, co-ions, and desorption experiments were performed for effective Cr(VI) and MO removal. The Cr(VI) and MO removal rate of the MXenes was very fast, and the kinetic system was driven by pseudo-second-order kinetics. The sorption isotherm closely well-tailored with the Langmuir isotherm, and the maximum removal efficiencies were 104 and 94.8 mg/g for Cr(VI) and MO, respectively. The MXenes was successfully regenerated by 0.1 M NaOH aqueous solution and can be repeatedly recycled. The uptake of Cr(VI) and MO by the MXenes was mainly due to chemical adsorption, namely electrostatic adsorption, complexation, surface interactions, and ion exchange mechanisms. This investigation demonstrates the selectivity and feasibility of the MXenes as a real adsorbent for eliminating Cr(VI) and MO from the aqueous environment.     

Experimental investigation and statistical analysis of additively manufactured onyx-carbon fiber reinforced composites

Availability of additive manufacturing has influenced the scientific community to improve on production and versatility of the components created with several associated technologies. Adding multiple substances through superimposing levels is considered as a part of three-dimensional (3D) printing innovations to produce required products. These technologies are experiencing an increase in development nowadays. It requires frequently adding substance and has capacity to fabricate extremely complex geometrical shapes. However, the fundamental issues with this advancement include alteration of capacity to create special products with usefulness and properties at an economically viable price. In this study, significant procedural parameters: layer designs/ patterns (hexagonal, rectangular and triangular) and infill densities (30%, 40%, and 50%) were considered to investigate into their effects on mechanical behaviors off fused deposition modeling or 3D-printed onyx-carbon fiber reinforced composite specimens, using a high-end 3D printing machine. Mechanical (tensile and impact) properties of the printed specimens were conclusively analyzed. From the results obtained, it was observed that better qualities were achieved with an increased infill density, and rectangular-shaped design exhibited an optimum or maximum tensile strength and energy absorption rate, when compared with other counterparts. The measurable relapse conditions were viably evolved to anticipate the real mechanical qualities with an accuracy of 96.4%. In comparison with other patterns, this was more closely predicted in the rectangular design, using regression models. The modeled linear regression helps to define the association of two dependent variables linked with properties of the dissimilar composite material natures. The models can further predict response of the quantities before and also guide practical applications.     

Synthesis of alginate beads filled with nanohydroxyapatite: An efficient approach for fluoride sorption

Nanohydroxyapatite (n‐HAp) powder is a promising adsorbent material with high defluoridation capacity (DC); however, it causes pressure drop during field applications. To overcome such problems and utilize the advantages of n‐HAp, it is aimed to prepare n‐HAp in a usable bead form with the support of alginate (Alg) biopolymer. n‐HApAlgLa composite beads were synthesized by introducing n‐HAp powder in Alg polymeric gel, and the resulting solution was dropped into La³⁺ ions for crosslinking. Defluoridation experiments were carried out in batch mode to optimize various influencing parameters like contact time, pH, challenger anions, initial fluoride concentrations, and temperature. The beads were characterized using Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy with energy‐dispersive X‐ray analyzer analysis. The sorption process was explained using diverse isotherms and kinetic models. The values of thermodynamic parameters indicate that the nature of fluoride is spontaneous and endothermic in nature. In field studies, n‐HApAlgLa beads reduce the fluoride concentration below the tolerance limit. The regeneration and reusability studies were proposed to effectively use the sorbent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41937.     

Modification of electrodes with nanostructured functionalized thiadiazole polymer film and its application to the determination of ascorbic acid

We report the electropolymerization of 2-amino-1,3,4-thiadiazole (ATD) on glassy carbon (GC) and indium tin oxide (ITO) electrodes in 0.10 M H₂SO₄. The electropolymerized ATD (p-ATD) film was characterized by cyclic voltammetry, attenuated total reflectance (ATR)-FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The AFM image showed that the p-ATD formed a spherical-like structure with a thickness of 25 nm. XPS of the p-ATD film showed binding energies at 398.7, 400.3 and 401.3 eV in the N 1s region corresponding to –N, –NH– and –N⁺H–, respectively, and at 285.5 and 287.0 eV in the C 1s region corresponding to C–N and CN, respectively. The appearance of binding energies at 285.5 and 287.0 eV confirmed that the p-ATD film proceeded via C–N and CN linkages and not via C–C or CC linkages. The p-ATD film deposited on the GC electrode was successfully used for the determination of ascorbic acid (AA) at physiological pH. The amperometric current was increased linearly from 7.5 × 10⁻⁸ to 2.0 × 10⁻⁵, and the detection limit was found to be 0.28 nM (S/N = 3).     

Electrochemical properties of microwave-assisted reflux-synthesized Mn<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles in different electrolytes for supercapacitor applications

The nanosized Mn₃O₄ particles were prepared by microwave-assisted reflux synthesis method. The prepared sample was characterized using various techniques such as X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman analysis, and transmission electron microscopy (TEM). Electrochemical properties of Mn₃O₄ nanoparticles were investigated using cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge analysis in different electrolytes such as 1 M KCl, 1 M Na₂SO₄, 1 M NaNO₃, and 6 M KOH electrolytes. XRD pattern reveals the formation of single-phase Mn₃O₄ nanoparticles. The FT-IR and Raman analysis also assert the formation of Mn₃O₄ nanoparticles. The TEM image shows the spherical shape particles with less than 50 nm sizes. Among all the electrolytes, the Mn₃O₄ nanoparticles possess maximum specific capacitance of 94 F g⁻¹ in 6 M KOH electrolyte calculated from CV. The order of capacitance obtained by various electrolytes is 6 M KOH > 1 M KCl > 1 M NaNO₃ > 1 M Na₂SO₄. The EIS and galvanostatic charge–discharge results further substantiate with the CV results. The cycling stability of Mn₃O₄ electrode reveals that the prepared Mn₃O₄ nanoparticles are a suitable electrode material for supercapacitor application.     

Mixed Mode Stress Intensity Factor Determination of Multiple Cracks in Hollow Circular Pipe

Failure of pressure vessels and piping due to high temperature applications occurs due to the formation of fatigue cracks caused by cyclic load. It is well known that, the consequences of collapses of pipes causing enormous disruption of daily life. Thus there is a need to design and manufacture the pipes with precision and care. The major cause of crack nucleation in pipes is due to corrosion and internal fluid pressure. The crack-tip stresses are determined using stress intensity factor (SIF). In the present work an attempt has been made to determine the SIF for multiple cracks in a circular pipe subjected to internal fluid pressure. Two surface cracks of same size were introduced at the inner wall of the tube. The crack depth ratio (a/t) ranging between 0.1 and 0.5 and crack aspect ratio (a/c) of 0.6 and 1.0 was considered. Internal fluid pressure of 100 MPa was applied at the inner surface of the pipe and the corresponding SIF was measured. SIF values were calculated with consideration of mode-II and mode-III fracture in order to predict the exact SIF. As available SIF solutions of cracked pipes are limited to mode-I fracture, present work presents the influence of additional influence of mode-II and mode-III fracture. It is observed that, as crack depth ratio increases, SIF also increases considerably for semi-circular cracks. Higher SIF values were observed at the crack surface region [S/S ₀ = ±1] compared to crack middle [S/S ₀ = 0] region. A crossover in SIF was noted at a crack depth ratio of 0.3. At higher crack depths, SIF values decrease at the crack surface region due to additional influence of mode-II and mode-III fracture. In contrast to semi-circular cracks, SIF values are higher at the crack surface region for semi-elliptic cracks irrespective of the crack depths.     

Retraction notice to: “Computer application in mathematics” [Comput. Math. Appl. 59 (1) (2009) 296–297]

This article has been retracted: please see Elsevier Policy on Article Withdrawal http://www.elsevier.com/locate/withdrawalpolicy.This article has been retracted at the request of the Publisher, as the article contains no scientific content and was accepted because of an administrative error. Apologies are offered to readers of the journal that this was not detected during the submission process.