Hybrid Laplace transform-finite element method to a generalized electromagneto-thermoelastic problem

A finite element method based on the Laplace transform technique is developed for a two-dimensional problem in electromagneto-thermoelasticity. The problem is in the context of the following generalized thermoelasticity theories: Lord–Shulman’s, Green–Lindsay’s, the Chandrasekharaiah–Tzou, as well as the dynamic coupled theory. The Laplace transform method is applied to the time domain and the resulting equations are discretized using the finite element method. The inversion process is carried out using a numerical method based on a Fourier series expansions. Numerical results compared with those given in literature prove the good performance of the used method. It is demonstrated that the Chandrasekharaiah–Tzou theory can be considered as an extension of Lord–Shulman’s, and the generalized heat conduction mechanism is completely different from the classical Fourier’s in essence.     

Enaminones in heterocyclic synthesis: Synthesis and chemical reactivity of 3‐anilino‐1‐substituted‐2‐propene‐1‐ one

The 3‐anilinoenones 3a,b were prepared from the corresponding 3‐dimemyl‐aminopropenones. The reactivity of 3a,b towards a variety of carbon and nitrogen nucleophiles as well as naphthoquinones is reported.     

Broom-like and flower-like heterostructures of silver molybdate through pH controlled self assembly

Silver molybdate microrods are self-assembled into micron sized, broom-like and flower-like structures. Our investigations indicate that through a simple hydrothermal process, large scale production of such structure is possible. Using ammonium molybdate and silver nitrate solutions as precursors, we were able to show that the self assembled architectures were dependent on the pH of the starting precursor material. To understand the formation and destructions of the flower-like morphology, a systematic broad range (from acidic to basic) of pH-controlled experiments were performed and its influence on the structure/microstructure of synthesized materials was investigated. Scanning electron microscopy studies revealed that the morphology and microstructure of the products varied significantly by changing pH values from 3 to 8 during mixing of the reactants. pH = 3 and 4 resulted in the self assembly of monoclinic Ag₂(Mo₂O₇) microrods into broom-like structures, whereas pH = 5 resulted into the flower-like morphology of mixed phase of monoclinic and triclinic Ag₂Mo₂O₇. We also found that increasing the pH after a certain threshold value (for example pH > 6) resulted in total collapse of the flower-like morphology. Further increase of the pH to 7 and 8 resulted, the formation of microparticles of Ag₂MoO₄. A tentative scheme based on the pH-driven evolution of the self-assembly has been given to explain the formation of the observed heterostructures. Preliminary electrical characterization of thin films of the flower-like structures rendered non-linear current–voltage (I–V) responses. We also observed a strong hysteresis in the I–V responses of the flower-like structures developed under high bias conditions.     

Synthesis,in vitro antimicrobial assessment,and computational investigation of pharmacokinetic and bioactivity properties of novel trifluoromethylated compounds using in silico ADME and toxicity prediction tools

1,3-Dipolar cycloaddition reactions of a sugar-based trifluoromethylated nitrone-to-maleimide and allyl bromide afforded a series of cycloadducts in good yield. The same nitrone reacts with propargyl acetate lead, after rearrangement of 4-isoxazoline, to aziridine with good yield. The obtained compounds were evaluated for their in vitro antimicrobial potency. Additionally, we are interested in predicting their physicochemical parameters such as lipophilicity and bioactivity score as well as their pharmacokinetic properties such as absorption, distribution, metabolism, and excretion (ADME) such as plasma protein binding (PPB) penetration of the blood–brain barrier (BBB), human intestinal absorption (HIA), cellular permeability (PCaco-2), cell permeability of Madin–Darby canine kidney (PMDCK), P-glycoprotein (P-gp) efflux, CYP inducers, substrates and inhibitors’ skin and permeability (PS), and their toxicological behavior [mutagenicity, carcinogenicity, acute, environmental, cardiotoxicity (hERG inhibition)] using in silico computational methods. Also, we aimed to validate QSAR models for the elucidation of their antitarget using 32 sets of end-points (IC50, Ki and Kact). The obtained result provides good information about the pharmacotherapy potential and toxicity of the examined molecules with good compliance between in vitro antimicrobial and the predicted properties. Findings indicated and encouraged the use of these compounds and their derivatives for further in vivo evaluations in the design and the elucidation of the intrinsic mechanisms as well as the efficacy of the selected powerful drug.     

Antimicrobial,Antioxidant, Anti-Acetylcholinesterase,Antidiabetic, and Pharmacokinetic Properties of Carum carvi L. and Coriandrum sativum L. Essential Oils Alone and in Combination

Herbs and spices have been used since antiquity for their nutritional and health properties, as well as in traditional remedies for the prevention and treatment of many diseases. Therefore, this study aims to perform a chemical analysis of both essential oils (EOs) from the seeds of Carum carvi (C. carvi) and Coriandrum sativum (C. sativum) and evaluate their antioxidant, antimicrobial, anti-acetylcholinesterase, and antidiabetic activities alone and in combination. Results showed that the EOs mainly constitute monoterpenes with γ-terpinene (31.03%), β-pinene (18.77%), p-cymene (17.16%), and carvone (12.20%) being the major components present in C. carvi EO and linalool (76.41%), γ-terpinene (5.35%), and α-pinene (4.44%) in C. sativum EO. In comparison to standards, statistical analysis revealed that C. carvi EO showed high and significantly different (p < 0.05) antioxidant activity than C. sativum EO, but lower than the mixture. Moreover, the mixture exhibited two-times greater ferric ion reducing antioxidant power (FRAP) (IC₅₀ = 11.33 ± 1.53 mg/mL) and equipotent chelating power (IC₅₀ = 31.33 ± 0.47 mg/mL) than the corresponding references, and also potent activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC₅₀ = 19.00 ± 1.00 mg/mL), β-carotene (IC₅₀ = 11.16 ± 0.84 mg/mL), and superoxide anion (IC₅₀ = 10.33 ± 0.58 mg/mL) assays. Antimicrobial data revealed that single and mixture EOs were active against a panel of pathogenic microorganisms, and the mixture had the ability to kill more bacterial strains than each EO alone. Additionally, the anti-acetylcholinesterase and α-glucosidase inhibitory effect have been studied for the first time, highlighting the high inhibition effect of AChE by C. carvi (IC₅₀ = 0.82 ± 0.05 mg/mL), and especially by C. sativum (IC₅₀ = 0.68 ± 0.03 mg/mL), as well as the mixture (IC₅₀ = 0.63 ± 0.02 mg/mL) compared to the reference drug, which are insignificantly different (p > 0.05). A high and equipotent antidiabetic activity was observed for the mixture (IC₅₀ = 0.75 ± 0.15 mg/mL) when compared to the standard drug, acarbose, which is about nine times higher than each EO alone. Furthermore, pharmacokinetic analysis provides some useful insights into designing new drugs with favorable drug likeness and safety profiles based on a C. carvi and C. sativum EO mixture. In summary, the results of this study revealed that the combination of these EOs may be recommended for further food, therapeutic, and pharmaceutical applications, and can be utilized as medicine to inhibit several diseases.     

The effect of heat-treatment on the physico-chemical properties of silica aerogel prepared by sub-critical drying technique

Synthesis of transparent and crack-free monoliths of silica aerogel by sub-critical drying technique is reported in the present article. Silane ageing with 50% tetraethylorthosilicate:ethanol followed by solvent exchange using ethanol was adopted. The effect of heat-treatment on the textural and physical characteristics of silica aerogel was evaluated. The chosen composition resulted in a high surface area silica aerogel of 1,000 m² g⁻¹ and a pore volume of 1.4 cm³ g⁻¹ at room temperature. The aerogel heat-treated at 900 °C possessed a surface area of 450 m² g⁻¹ with a pore volume of 0.4 cm³ g⁻¹. The decrease in surface area and pore volume was associated with the sintering process. The present technique seems advantageous in preserving the high surface area of the material at high temperatures. The XRD studies showed that the amorphous nature of aerogel matrix was retained till 1,400 °C, beyond which it crystallized to phase pure crystoballite.     

Microwaves in organic synthesis: Synthesis of pyridazinones,phthalazinones and pyridopyridazinones from 2‐oxo‐arylhydrazones under microwave irradiation

The phenylhydrazones 1a‐d condensed with ethyl cyanoacetate to yield pyridazinones 2a‐d that reacted with sulphur in presence of piperidine to yield the aminothienopyridazineones 3a,b that reacted with electron poor olefins and acetylenes to yield phthalazines 10‐12. The condensed aminothiophenes 3a,b reacted with dimethylformamide dimethylacetal to yield amidines 13a,b. Compounds 2a,b condensed with dimethylformamide dimethylacetal to yield the trans enamines 16a,b that cyclized readily into the pyridopyridazinones 17a,b on treatment with ammonium acetate in presence of acetic acid. Compounds 2a‐d reacted also with benzylidenemalononitrile to yield the phthalazinones 21a‐d. The reactions were conducted both by microwave heating and conventional heating. Better yields in much shorter reaction times were achieved by microwave heating.     

Energy decay in thermoelastic diffusion theory with second sound and dissipative boundary

We study the energy decay of the solutions of a linear homogeneous anisotropic thermoelastic diffusion system with second sound and dissipative boundary of the form $$\mathbf{T}(x,t)n(x) = -\gamma_0v(x,t) -\int_0^\infty \lambda(s)v^t(x,s) ds. $$ This boundary condition well describes a material for which the domain outside the body consists in a material of viscoelastic type. Models of boundary conditions including a memory term which produces damping were proposed in Fabrizio and Morro (Arch. Ration. Mech. Anal. 136:359–381, 1996) in the context of Maxwell equations and in Propst and Prüss (J. Integral Equ. Appl. 8:99–123, 1996) for sound evolution in a compressible fluid. The thermal and diffusion disturbances are modeled by Cattaneo-Maxwell law for heat and diffusion equations to remove the physical paradox of infinite propagation speed in the classical theory within Fourier’s law. The system of equations in this case is a coupling of three hyperbolic equations. By introducing a boundary free energy, we prove that, if the kernel λ exponentially decays in time then also the energy exponentially decays. Finally, we generalize the obtained results to the Gurtin-Pipkin model.