Bright and singular soliton solutions of the conformable time-fractional Klein–Gordon equations with different nonlinearities

Finding the exact solutions of nonlinear fractional differential equations has gained considerable attention, during the past two decades. In this paper, the conformable time-fractional Klein–Gordon equations with quadratic and cubic nonlinearities are studied. Several exact soliton solutions, including the bright (non-topological) and singular soliton solutions are formally extracted by making use of the ansatz method. Results demonstrate that the method can efficiently handle the time-fractional Klein–Gordon equations with different nonlinearities.     

Biodegradable Cell-Seeded Collagen Based Polymer Scaffolds for Wound Healing and Skin Reconstruction

In the present study a collagen-glycosaminoglycans scaffold, following chemical modifications, was prepared as an analog of the extracellular matrix (ECM) by a freeze drying method. Appropriate tests related to its use for wound healing (evaluation of the structure by scanning electron microscopy, swelling properties, biodegradability properties, Fourier transform infrared spectroscopy and cell culture) were done on the scaffolds. Amniotic fluid-derived stem (AFS) cell seeded scaffolds were shown to be potentially useful for wound healing.     

Stability of Runge-Kutta methods for delay differential systems with multiple delays

The stability of Runge-Kutta methods for systems of delay differentialequations (DDEs) with multiple delays is considered. The stabilityregions of explicit and implicit Runge-Kutta methods are discussedwhen they are applied to asymptotically stable linear DDEs withmultiple delays. A simple estimate on the stability regionsof explicit Runge-Kutta methods is presented. It is shown thatthe stable step-size for numerical integration of DDEs withmultiple delays can be easily selected by means of the estimate.     

Kinetics and mechanism of the photochemical reaction of Octacyanomolybdate (IV) and Diethylenetriamine

Photolysis of [Mo(CN)₈]⁴⁻ in the presence of diethylenetriamine (dien) leads to the complexation of ligand via hydrogen in the stoichiometry 2:1. The mechanism of the complexation was investigated by spectroscopy absorption and the rate constants and the quantum yield determined. Rate constants and quantum yields for the formation of the final products were found to depend on pH, ligand, and metal cyanide concentration. The values are a maximum at pH 7.4. At pH >7.4 the reverse reaction, generating octacyanomolybdate complex from the heptacyano species, is faster. At low pH, the ligand is protonated and less reactive; hence, the rate of reaction and quantum yield values decrease. The ionic strength does not affect the reaction rate, implying an associative mechanism for the photochemical reaction with dien, supported by the rate law. The observed rate law is: © 1999 John Wiley & Sons, Inc. J Chem Kinet 31: 89–93, 1999     

Evaluation of the thermal oxidative stability of polyimides via TGA techniques

Thermogravimetric analysis (TGA) has been used for many years to evaluate polymer thermal stability. The objective of this study is to determine if weight-loss curves from TGA and isothermal TGA (IGA) can be used to determine degradation activation energies and thus rank the thermal stability (TS) and thermooxidative stability (TOS) for selected polyimides. Two high-temperature stable addition-cured polyimides and two aromatic condensation polyimides, all four containing fluorinated connecting linkages in the dianhydride monomers, were compared. Three TGA kinetic methods (Coats/Redfern, Ingraham/Marier, Horowitz/Metzger) were used to determine the activation energy for decomposition in air. The results were then used to rank polyimide stability compared to more traditional rankings based on long-term isothermal air aging weight-loss (IWL) studies and thermal decomposition temperatures (T_d) from TGA data. Use of TGA coupled to a Fourier transform infrared (TGA–FTIR) spectrophotometer allowed for the simultaneous identification and relative quantification of evolved decomposition products (CO₂, CO, ArNCO, and CHF₃) of the four polyimides degraded in air or nitrogen. Isothermal TGA–FTIR (IGA–FTIR) was also done in air to determine the relative rate of product evolution at a constant temperature. Activation energies using TGA and IGA data were determined and then compared with IWL values for the degradation of the polyimide to examine for correlations of real-life thermal oxidative aging to accelerated aging techniques. The Coats/Redfern method and T_d were found to best reproduce stability rankings of those from long-term, high-temperature IWL studies. Together, they may provide a time-saving technique to evaluate polyimide thermal oxidative stability. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3943–3956, 1999     

Different Dimensionalities,Morphological Advancements and Engineering of g-C3N4-Based Nanomaterials for Energy Conversion and Storage

Graphitic carbon nitride (g-C₃N₄) has gained tremendous interest in the sector of power transformation and retention, because of its distinctive stacked composition, adjustable electronic structure, metal-free feature, superior thermodynamic durability, and simple availability. Furthermore, the restricted illumination and extensive recombination of photoexcitation electrons have inhibited the photocatalytic performance of pure g-C₃N₄. The dimensions of g-C₃N₄ may impact the field of electronics confinement; as a consequence, g-C₃N₄ with varying dimensions shows unique features, making it appropriate for a number of fascinating uses. Even if there are several evaluations emphasizing on the fabrication methods and deployments of g-C₃N₄, there is certainly an insufficiency of a full overview, that exhaustively depicts the synthesis and composition of diverse aspects of g-C₃N₄. Consequently, from the standpoint of numerical simulations and experimentation, several legitimate methodologies were employed to deliberately develop the photocatalyst and improve the optimal result, including elements loading, defects designing, morphological adjustment, and semiconductors interfacing. Herein, this evaluation initially discusses different dimensions, the physicochemical features, modifications and interfaces design development of g-C₃N₄. Emphasis is given to the practical design and development of g-C₃N₄ for the various power transformation and inventory applications, such as photocatalytic H₂ evolution, photoreduction of CO₂ source, electrocatalytic H₂ evolution, O₂ evolution, O₂ reduction, alkali-metal battery cells, lithium-ion batteries, lithium–sulfur batteries, and metal-air batteries. Ultimately, the current challenges and potential of g-C₃N₄ for fuel transformation and retention activities are explored.     

Crystalloluminescence produced during the micro-fracture of growing crystallites

The present paper reports the theory of crystalloluminescence (CRL) produced during the micro-fracture of growing crystallites. Surface charges may be developed during the micre-fracture of crystallites due to several processes like piezoelectrification, movement of charged dislocations, barodiffusion of defects near the moving crack etc. The surface charges may be neutralized by the movement of charge carriers produced due to the dielectric breakdown near the surface of crystallites and consequently the recombination luminescence may occur. Considering the basic concepts of crystallization from the supersaturated solution, expressions are derived which are able to explain satisfactorily the temporal, thermal, spectral concentration and other characteristics of the CRL. It is shown that the induction period for crystal nucleation, lifetime of supersaturation, size of crystallites and time constant for the relaxation of charges on the newly created surfaces may be determined from the CRL measurements.