Different stability‐indicating chromatographic methods for specific determination of paracetamol,dantrolene sodium,their toxic impurities and degradation products

A well‐known analgesic (paracetamol, PAR) and skeletal muscle relaxant [dantrolene sodium (DNS)] have been analyzed without interference from their toxic impurities and degradation products. The studied PAR impurities are the genotoxic and nephrotoxic p‐amino phenol (PAP) and the hepatotoxic and nephrotoxic chloroacetanilide, while 5‐(4‐nitrophenyl)‐2‐furaldehyde is reported to be a mutagenic and carcinogenic degradation product of DNS. The five studied components were determined and quantified by TLC–densitometric and RP‐HPLC methods. TLC–densitometry (method 1) used TLC silica gel and chloroform–ethyl acetate–acetic acid–triethylamine (7:3:0.5:0.05, by volume) as the mobile phase with UV scanning at 230 nm, while RP‐HPLC (method 2) was based on separation on a C₁₈ column using methanol–water (55:45, v/v pH 3 with aqueous formic acid) as mobile phase at 1 mL/min and detection at 230 nm. The developed methods were used for determination and quantification of the five studied components in different laboratory‐prepared mixtures. The were also applied for analysis of Dantrelax^® compound capsules where no interference among the studied components with each other or from excipients was observed. The methods were validated as per International Conference on Harmonization guidelines, and they compared favorably with the reported ones.     

New all-cis-tetra(p-tolyl)cyclotetrasiloxanetetraol and its functionalization

New all-cis-tetra(p-tolyl)cyclotetrasiloxanetetraol and its derivatives with Si(CH = CH₂)Me and Si(H)Me₂ groups have been prepared and characterized by IR and NMR spectroscopy, GPC, mass spectrometry, TGA and DSC. Molecular and crystalline structures of the tetraol and its derivative with four Si(CH = CH₂)Me groups have been determined by single-crystal X-ray diffraction.     

A controllability perspective of dynamic soaring

Dynamic soaring is an exquisite flying technique to acquire energy from the atmospheric wind shear. In this study, a geometric nonlinear controllability analysis of an unmanned aerial vehicle (UAV) under dynamic soaring conditions is performed. To achieve such an objective, the state-of-the-art mathematical tools of nonlinear controllability are summarized and presented to an aeronautical engineering audience. The dynamic soaring optimal control problem is then formulated and solved numerically. The controllability of the UAV along the optimal soaring trajectory is analyzed. More importantly, the geometric nonlinear controllability characteristics of generic flight dynamics are analyzed in the presence and absence of wind shear to provide a controllability explanation for the role of wind shear in the physics of dynamic soaring flight. It is found that the wind shear is instrumental in ensuring controllability as it allows the UAV attitude controls (pitch and roll) to play the role of thrust in controlling the flight path angle. The presented analysis represents a controllability-based mathematical proof for the energetics of flight physics.     

Nanostructured Pyrophosphate Na2PdP2O7‐Catalyzed Suzuki‐Miyaura Cross‐Coupling Under Microwave Irradiation

Nanostructured palladium pyrophosphate (Na₂PdP₂O₇) catalyst was synthesized and well characterized by using different techniques (TGA, XRD, SEM, TEM....). This nanocatalyst exhibited excellent catalytic activity in the synthesis of biaryl compounds via Suzuki‐Miyaura cross‐coupling to produce their corresponding products in good to excellent yields under mild conditions. The catalyst is recyclable and was recycled for four runs for the reaction of 4‐bromoacetophenone with phenylboronic acid without appreciable loss of its catalytic activity.     

Evaluation of newly synthesized derivatives of bis(hydrazine‐1‐carbothioamide) and their metal complexes synthesized in bulk and nano size as potent anticancer agents

A series of new metal complexes were synthesized in both bulk and nano size using green methods, starting with the reaction of (E)‐N′‐[(E)‐2‐bromobenzylidene]‐4‐oxo‐4‐(piperidin‐1‐yl)but‐2‐enehydrazide with thiosemicarbazide and different metal halides such as CuI·2H₂O, CuCl₂·2H₂O, CoCl₂·2H₂O, and ZnCl₂·2H₂O, and metal nitrate such as Ga(NO₃)₃·2H₂O. Structures of these metal complexes were confirmed using different spectroscopic methods, elemental analysis, electronic spectra, and microanalytical methods (scanning electron microscopy and transmission electron microscopy) for nano complexes. The distorted octahedral geometry for all complexes was suggested based on magnetic moments and electronic spectral studies. The cytotoxic activity of the compounds was investigated against human hepatocellular carcinoma (HepG2) and human colorectal carcinoma (HCT‐116) cell lines. Most tested compounds had higher inhibitory activity than the standard vinblastine drug. Interestingly, the nano‐sized Ga(III) complex 11 was the most potent compound against the two tested cell lines, with 50% inhibitory concentration (IC₅₀) of 2.56 μg/mL for HepG2, compared with the reference drug vinblastine (IC₅₀ 15.6 μg/mL), and IC₅₀ 4.64 μg/mL for HCT‐116, compared with the standard (IC₅₀ 13.9 μg/mL). The bioassay results helped us identify new potent and selective anticancer agents.     

Evaluation of Row-wise Manipulations for the Forensic Differentiation of Malaysian Soils based on Ultra-performance Liquid Chromatographic Profiles

Journal of Analytical Chemistry - Soil is useful physical evidence for linking a suspect/victim to a particular crime scene. However, the discrimination of soils from neighboring locations can be a...     

Synthesis and Characterization of Polyaniline/Zeolite X Composites as Anticorrosion Coating Materials

The main target of this work is to choose the best preparation conditions to have a perfect yield of the new composites prepared from mixing Zeolite X with polyaniline. The preparation of polyaniline and polyaniline/Zeolite X composites as anticorrosion coat was studied. The composites were synthesized and characterized by X-ray diffraction, Fourier transform infrared spectroscopy and UV–visible spectroscopy techniques, which showed the successful synthesis.     

Controlled and scalable torsional actuation of twisted nylon 6 fiber

Large‐scale torsional actuation occurs in twisted fibers and yarns as a result of volume change induced electrochemically, thermally, photonically, and other means. A quantitative relationship between torsional actuation (stroke and torque) and volume change is here introduced. The analysis is based on experimental investigation of the effects of fiber diameter and inserted twist on the torsional stroke and torque measured when heating and cooling nylon 6 fibers over the temperature range of 26–62 °C. The results show that the torsional stroke depends only on the amount of twist inserted into the fiber and is independent of fiber diameter. The torque generated is larger in fibers with more inserted twist and with larger diameters. These results are successfully modeled using a single‐helix approximation of the twisted fiber structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1278–1286     

Surfactant dispersed multi-walled carbon nanotube/polyetherimide nanocomposite membrane

Carbon nanotube based nanocomposite membranes have been fabricated through solution casting by embedding multi-walled carbon nanotubes (MWCNTs) within polyetherimide (PEI) polymer host matrix. In order to achieve fine dispersion of nanotubes and facilitate strong interfacial adhesion with the polymer matrix, the nanotubes were first treated with surfactants of different charges, namely anionic sodium dodecyl chloride, cationic cetyl trimethyl ammonium chloride and non-ionic Triton X100, prior to the dispersion in the PEI dope solution. Dispersion of MWCNTs in N-methyl-2-pyrrolidone solvent showed that the agglomeration and entanglement of the nanotubes were greatly reduced upon the addition of Triton X100. Scanning electron microscopy and atomic force microscopy examination has evidenced the compatibility of Triton X100 dispersed MWCNTs with the polymer matrix in which a promising dispersion and adhesion has been observed at the MWCNT-PEI interface. The increase in both thermal stability and mechanical strength of the resulting Triton X100 dispersed MWCNT/PEI nanocomposite indicated the improved interaction between MWCNTs and PEI. This study demonstrated the role of Triton X100 in facilitating the synergetic effects of MWCNTs and PEI where the resulting composite membrane is anticipated to have potential application in membrane based gas separation.