Developing two efficient adaptive Newton‐type methods with memory

In this paper, we derive two general adaptive methods with memory in the class of Newton‐type methods by modifying and introducing one and two self accelerators over a variant of Ostrowski's method. The idea of introducing adaptive self‐accelerator (via all the old information for Newton‐type methods) is new and efficient in order to obtain a higher high efficiency index. Finally, we provide convergence analysis and numerical implementations to show the feasibility and applicability of the proposed methods.     

Combinatorial Library Synthesis of N‐arylquinoline Derivatives in Aqueous Medium

N‐aryl quinoline derivatives have been prepared by sequential one‐pot reaction of dimedone, aniline, malononitrile and arylaldehydes. The reactions were performed in two different conditions, refluxing in ethanol without catalyst and heating in ethanol/water (1:1) in the presence of imidazole as an organocatalyst. Use of organocatalyst causes shorter reaction times and higher yields.     

Functionalization of Graphene Sheets via Chemically Grafting of PMMA Chains Through in-situ Polymerization

In this work, we report the preparation of graphene nanoplatelet which covalently functionalized with PMMA chains by introduction of vinyl groups onto graphene surface through simple esterification reaction between hydroxyl groups of graphite oxide and methacrylic anhydride. The synthesis is followed by in-situ polymerization with MMA monomers. The structural properties were characterized with X-ray diffraction spectroscopy (XRD) and scanning electronic microscopy (SEM) that showed the crystalline graphite is converted to individual layers during the synthesis steps. The grafting of PMMA chains was monitored with IR spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The TGA results revealed 40% wt of PMMA chains chemically grafted onto graphene surface. Significant increase in glass transition temperature (T_g) and existence of polymer chains in two positions (physically absorbed and chemically grafting onto graphite surface) are indicated by differential scanning calorimetric (DSC) analysis.     

Magnetic solid‐phase extraction method for extraction of some pesticides in vegetable and fruit juices

A new version of magnetic solid‐phase extraction performed in a narrow‐bore tube has been proposed for the extraction and preconcentration of different pesticides from various vegetable and fruit juices followed by gas chromatography. A few milligrams of C₈@SiO₂@Fe₃O₄ nanoparticles are added into an aqueous sample solution placed in a narrow‐bore tube. The sorbent particles move down through the tube under gravity and are collected at the end of the tube by applying an external magnetic field. The end of the tube is narrower and it is connected to a stopcock. After a predetermined time, the stopcock is opened and the solution is passed through the bed of the sorbent maintained by the magnet. Then the adsorbed analytes are desorbed using an elution solvent. To achieve high enrichment factors, a dispersive liquid–liquid microextraction method is carried out. The nanoparticles were characterized by scanning electron microscopy, X‐ray diffraction, and FTIR spectroscopy. Under the optimum extraction conditions, limits of detection and quantification were in the ranges of 0.1–0.3 and 0.3–0.9 μg/L, respectively. High enrichment factors (1166–1605) and good extraction recoveries (58–80%) were obtained.     

Green and highly efficient synthesis of pyranopyrazoles in choline chloride/urea deep eutectic solvent

A simple and efficient multicomponent protocol, using ammonium deep eutectic solvent as a dual catalyst and environmentally benign reaction medium, is developed for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. This operationally simple protocol does not involve tedious workup or purification, affording the target compounds in short reaction times and excellent yields and avoiding the use of environmentally hazardous solvents and catalysts.     

Inclusion of sulfamethoxazole in a novel CuFe2O4 nanoparticles/mesoporous silica‐based nanocomposite: Release kinetics and antibacterial activity

In this work, we aimed to improve the antibacterial activity of sulfamethoxazole (SMX) via its inclusion in a newly synthesized nanocomposite composed of CuFe₂O₄ nanoparticles and poly(vinyl alcohol)/silica‐based mesoporous materials. Characterization of this formulation using different techniques confirmed the correct synthesis and showed that this mesoporous nanocomposite had an amorphous structure with relatively high surface area of 1,620.7 m² g^?1 and mean pore diameter of 1.6576 nm. Zeta potential of the formulation was obtained to be zero which led to its higher bioavailability in comparison to pure SMX with negative zeta potential. Antibacterial property of the prepared formulation against Staphylococcus aureus and Escherichia coli was evaluated. Minimum inhibitory concentration of the SMX‐loaded mesoporous nanocomposite was considerably lower than those of pure SMX, indicating the efficient function of the mesoporous material as a delivery system. Kinetics of SMX release was also studied using zero‐order, first‐order, Higuchi, and Korsmeyer–Peppas kinetics models. According to the obtained results, the release kinetics was found to obey zero‐order model. So the possibility of sustained release of SMX from the synthesized carrier may be suggested.     

Flame atomic absorption determination of trace amounts of cadmium after preconcentration using a thiol-containing task-specific ionic liquid

Dispersive liquid-liquid microextraction (DLLME) based on a task-specific ionic liquid (TSIL) was developed for the extraction and preconcentration of trace amounts of cadmium from aqueous samples, followed by flame atomic absorption spectrometry (FAAS) determination. In the proposed approach, cadmium ions are extracted from aqueous samples using small volumes of trioctylmethylammonium thiosalicylate (TOMATS) dissolved in acetone. TOMATS is a thiol-containing TSIL that can form metal thiolate complexes due to the chelating effect of the ortho-positioned carboxylate group relative to the thiol functionality. The main parameters affecting the performance of DLLME based on TSIL, such as pH, amount of TOMATS, extraction time, injection volume, salt addition, and centrifugation time, were optimized. Under optimum conditions, an LOD of 1.16 ng/mL and a good RSD of 1.8% at 60.0 ng/mL were obtained (n=7). The proposed method was applied to tap water, wastewater, well water, and milk samples. The results showed that DLLME based on TSIL combined with FAAS is a rapid, simple, sensitive, selective, low cost, volatile organic solvent-free, and efficient analytical method for the separation and determination of trace amounts of cadmium ions.     

Oxygen- versus carbon-coordination of the alpha-stabilized phosphorus ylide Ph<Subscript>3</Subscript>P=C(H)R in palladacycles bearing secondary amines

The ortho-metalated complex [Pd(x){κ ² (C,N)-[C₆H₄CH₂NRR′ (Y)}] (2a–4a and 2b–3b) was prepared by refluxing in benzene equimolecular amounts of Pd(OAc)₂ and secondary benzylamine [a, EtNHCH₂Ph; b, t-BuNHCH₂Ph followed by addition of excess NaCl. The reaction of the complexes [Pd(x){κ ² (C,N)-[C₆H₄CH₂NRR′ (Y)}] (2a–4a and 2b–3b) with a stoichiometric amount of Ph₃P=C(H)COC₆H₄-4-Z (Z = Br, Ph) (ZBPPY) (1:1 molar ratio), in THF at low temperature, gives the cationic derivatives [Pd(OC(Z-4-C₆H₄C=CHPPh₃){κ ² (C,N)-[C₆H₄CH₂NRR′(Y)}] (5a–9a, 4b–6b, and 4b′–6b′), in which the ylide ligand is O-coordinated to the Pd(II) center and trans to the ortho-metalated C(6)H(4) group, in an “end-on carbonyl”. Ortho-metallation, ylide O-coordination, and C-coordination in complexes (5a–9a, 4b–6b, and 4b′–6b′) were characterized by elemental analysis as well as various spectroscopic techniques.     

Modelling of austenite grain growth kinetics in a microalloyed steel (30MSV6) in the presence of carbonitride precipitates

Austenite grain growth kinetics in the presence of secondary precipitates of a microalloyed steel (30MSV6) was studied employing quantitative metallographic techniques. Austenitizing experiments were carried out at 1,000, 1,100 and 1,200?°C. According to the experimental data, abnormal grain growth behaviour is observed at 1,100?°C while it is normal at 1,000 and 1,200?°C. TEM observation represents multicomponent carbonitride precipitate, (Ti,V)(C,N), in the as-received steel with a mean radius of 35?nm. A mathematical model is proposed considering austenite grain growth along with dissolution and coarsening kinetics of the multicomponent precipitates. The austenite grain growth model for short-term non-isothermal and subsequent long-term isothermal heating stages was developed using a statistical approach. The model includes an algorithm to estimate the size distribution of austenite grains. Precipitate mean field dissolution and Lifshitz–Slyozov–Wagner coarsening models were integrated in the proposed model to calculate the pinning pressure retarding the grain boundary movement. The mean austenite grain size and the grain size distribution (normal and abnormal) calculated by the model are in good agreement with experimental data.     

The Divisibility Graph of finite groups of Lie type

The Divisibility Graph of a finite group G has vertex set the set of conjugacy class sizes of non-central elements in G and two vertices are connected by an edge if one divides the other. We determine the connected components of the Divisibility Graph of the finite groups of Lie type in odd characteristic.