Analysis of Solvent Effect on Mechanical Properties of Poly(ether ether ketone) Using Nano-indentation

Poly (ether ether ketone)(PEEK) is a high-performance semi-crystalline thermoplastic polymer.Exposure of the polymeric surface to solvents can have a strong effect like softening/swelling of polymeric network or dissolution.In this study, nano-indentation analysis was performed to study the effect of acetone on the surface mechanical properties of PEEK using different exposure time.The experiments were performed with a constant loading rate (10 nm/s) to a maximum indentation displacement (1000 nm).A 30-second hold segment was included at the maximum load to account for any creep effects followed by an unloading segment to 80% unloading.The indentation hardness and the elastic modulus were computed as a continuous function of the penetration displacement in the continuous stiffness mode (CSM) indentation.The experimental data showed that the peak load decreased from ~5.2 mN to ~1.7 mN as exposure time in solvent environment increased from 0 to 18 days.The elastic modulus and the hardness of PEEK samples also displayed a decreasing trend as a function of exposure time in the solvent environment.Two empirical models were used to fit the experimental data of hardness as a function of exposure time which showed a good agreement with the experimental values.     

Ni@zeolite-Y nanoporous; a valuable and efficient nanocatalyst for the synthesis of N-benzimidazole-1,3-thiazolidinones

In this project, Ni(II) ion stabilized on zeolite-Y (NNZ) was developed as a high efficient nanoporous catalyst for the synthesis of 3-benzimidazolyl-1,3–thiazolidin-4-one derivatives via condensation of 2-aminobenzimidazole, aromatic aldehydes and thioglycolic acid in ethanol under ambient conditions. Compared with conventional protocols, this methodology has promising features such as the use of inexpensive, stable, recyclable and safe catalyst, shorter reaction times and higher yields, nontoxic solvent and easy isolation of the products.     

Two-Dimensional Liquid Chromatography (2D-LC) in Pharmaceutical Analysis: Applications Beyond Increasing Peak Capacity

One-dimensional liquid chromatography (1D-LC) is not always capable of efficiently separating complex samples. This drawback is not solely due to the lack of column efficiency, but is mainly due to insufficient selectivity and the need to separate the analytes of interest with orthogonal retention mechanisms. In this regard, two-dimensional liquid chromatography (2D-LC) is currently attracting much interest for its markedly higher resolving power compared to one-dimensional separation. In this work, three applications of 2D-LC from the pharmaceutical industry are presented with the goal not only to increase peak capacity, but also to support investigations. In the first application, the retention times of peaks of interest are matched under different mobile phase conditions for the purpose of transferring the method from a mass spectrometry (MS) incompatible buffer to an MS compatible buffer. The second application includes developing a method for simultaneous detection and quantitation of degradants and aggregates in a biologics and small molecule combination product. The third application supports method development by confirming the purity of separated peaks using orthogonal separation conditions in the first and second dimensions and to investigate mass balance issues where some peaks are expected to elute in the solvent front.     

Room temperature LPG resistive sensor based on the use of a few-layer graphene/SnO<Subscript>2</Subscript> nanocomposite

A nanocomposite consisting of a few layers of graphene (FLG) and tin dioxide (SnO₂) was prepared by ultrasound-assisted synthesis. The uniform SnO₂ nanoparticles (NPs) on the FLG were characterized by X-ray diffraction in terms of lattice and phase structure. The functional groups present in the composite were analyzed by FTIR. Electron microscopy (HR-TEM and FE-SEM) was used to study the morphology. The effect of the fraction of FLG present in the nanocomposite was investigated. Sensitivity, selectivity and reproducibility towards resistive sensing of liquid propane gas (LPG) was characterized by the I-V method. The sensor with 1% of FLG on SnO₂ operated at a typical voltage of 1 V performs best in giving a rapid and sensitive response even at 27 °C. This proves that the operating temperature of such sensors can be drastically decreased which is in contrast to conventional metal oxide LPG sensors.

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Graphical abstract Schematic of a room temperature gas sensor for liquefied petroleum gas (LPG). It is based on the use of a few-layered graphene (1 wt%)/SnO₂ nanocomposite that was deposited on an interdigitated electrode (IDEs). A sensing mechanism for LPG detection has been established.

     

Fixed-Point Technique for Implicit Complementarity Problem in Hilbert Lattice

In this paper, we consider and study the implicit complementarity problem in the setting of a Hilbert lattice. It has been shown that this problem can be formulated as a fixed-point problem by using a suitable change of variables. Moreover, this formulation allows us to prove the existence and uniqueness of solutions of the implicit complementarity problem.     

Synthesis and Cytotoxic Activity of Novel Pyrazoline Derivatives against Human Lung Tumor Cell Line (A549)

In the present investigation, a series of 5‐(‐4‐(substituted)phenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐toluidino methane thione and 5‐(substituted)phenyl‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐methoxy anilino methane thiones were synthesized and were examined against human lung tumor cell line (A549) in vitro using the MTT assay system. Among those tested, 5‐(4‐flurophenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐toluidino methane thione & 5‐(4‐chlorophenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐methoxy anilino methane thione showed more potent cytotoxicity against human lung tumor cell line (A549) than the other synthesized compounds.     

Silver Cyanide Complexes of Heterocyclic Thiones

Silver(I) cyanide complexes of various thiones (imidazolidine-2-thione, diazinane-2-thione and their derivatives) have been prepared and characterized by elemental analysis, i.r. and n.m.r. (¹H, ¹³C, ¹⁵N and ¹⁰⁷Ag) spectroscopy. It appears from the i.r. data that six out of the ten complexes are nonionic [>C=S—Ag—CN] while the remaining four exist as ionic species [Ag(>C=S)₂]⁺[Ag(CN)₂]^– in the solid state. An upfield shift in the ¹³C-n.m.r. and downfield shifts in the ¹H-, ¹⁵N- and ¹⁰⁷Ag-n.m.r. spectra are consistent with the sulfur coordination to silver(I). The n.m.r. data shows that the [>C=S—AgCN] complexes are stable in solution and do not undergo redistribution.     

Effects of Organic Salts on the Rate of Alkaline Hydrolysis of Phthalimide in the Presence Ofcationic Micelles

Pseudo-first order rate constants (k_obs) for alkaline hydrolysis of phthalimide (PTH), obtained at constant concentration of cetyltrimethylammonium bromide (CTABr) and 35°C, vary with the concentration of organic salts ([MX]) according to the relationship: k_obs = (k₀ + K [MX])/(1 + K [MX]) where and K are empirical parameters. The values of K at 0.01 M CTABr are nearly 2 times larger than the corresponding K values at 0.02 M CTABr for sodium benzoate, disodium phthalate and disodium isophthalate.