An algorithm for overlapped chromatogram separation

Non-negative matrix factorization (NMF) is a recently developed method for real time data analysis. In the past it has been used for facial recognition and spectral data analysis. Most of the NMF algorithms do not converge to a stable limit point and uniqueness in results is also a problem in NMF. To improve the convergence, a new NMF algorithm with modified multiplicative update (ML-NMFmse) has been proposed in this work for strongly overlapped and embedded chromatograms separation. To get same results for all the runs, instead of random initialization, three different initialization methods have been used namely, ALS–NMF (robust initialization), NNDSVD based initialization and EFA based initializations. The proposed ML-NMFmse algorithm is applied on the simulated and experimental overlapped chromatograms obtained for acetone and acrolein mixture, using Gas Chromatography–Flame Ionization Detector. Before applying NMF, Principal Component Analysis (PCA) was applied to determine number of components in the mixture taken. The result of proposed ML-NMFmse is compared with that of existing Multivariate Curve Resolution-Alternating Least Squares method in optimal conditions for both the algorithms. In the case of embedded chromatogram, the proposed ML-NMFmse with Robust method (ALS-NMF) of initialization performs better than all other methods. For a resolution of severely overlapped chromatograms, the proposed ML-NMFmse with NNDSVD method of initialization outperforms all other methods.     

Synthesis and characterization of 4,4′‐dihydroxy‐α‐methylstilbene crystal

4,4′‐dihydroxy‐α‐methylstilbene (DHAMS) was synthesized by condensation reaction with chloroacetone and phenol in the presence of concentrated sulfuric acid, and has been successfully grown by solution growth technique. This is the first report in the literature on the crystallization of DHAMS and exhibited the birefringent melt (liquid crystal property) of the optical properties. FTIR and FTNMR studies are in accordance with the structure. Good quality crystals were grown by slow evaporation technique by acetone as solvent. A transmission spectrum of the crystal was obtained in the region of 285 nm. The structural and optical properties were studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Surfactant Assisted Hydrothermal Synthesis of Superparamagnetic ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Efficient Visible-Light Photocatalyst for the Degradation of Organic Pollutant

Super paramagnetic ZnFe₂O₄ nanoparticles were prepared by a surfactant assisted (ethylamine) hydrothermal method along with heat treatment. The nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high resolution scanning electron microscopy, Transmission electron microscopy, vibrating sample magnetometer and diffuse reflectance spectra technique. From the analyses, influence of calcination temperature on the structural, vibrational, morphological, magnetic and optical properties of ZnFe₂O₄ nanoparticles were investigated. The ZnFe₂O₄ nanoparticles with an average particle size of 17 nm showed high photocatalytic activity in the degradation of methylene blue (90 %). This work demonstrates that ZnFe₂O4 can be used as a potential monocomponent in visible-light photocatalysis for the degradation of organic pollutants. Furthermore, the products were super paramagnetic and could be conveniently separated within 15 min and recycled by using simple magnet, which is very beneficial for the degradation of organic pollutants.     

Studies on thermotropic liquid crystalline polyphosphates containing photoreactive dual mesogens

A series of thermotropic liquid crystalline polyphosphates, containing photochromic molecules of stilbene in the backbone and substituted azobenzene in the side chain, were synthesized respectively. The inherent viscosity measurements were determined for all the polymers. The stability and char yield, T_g, T_m and T_i were investigated by thermal analysis. Polarizing optical microscopy of all the polymers exhibited birefringent melts with liquid crystalline behaviour. Variable temperature powder X-ray diffraction techniques were performed for confirmation of textures. UV-visible photolysis studies investigated the simultaneous behaviour of reactivity rates of crosslinking of stilbene units and isomerization, caused by azobenzene units in the main chain/side chain LCPs. Photoisomerization kinetics demonstrated the switching time rates for the trans-cis conversion of the azobenzene unit. A model polymer was synthesized and compared for the effect of stilbene in the main chain. Dipole moment values were calculated for the simulated low molecular mass of the pendant substituents to predict the polarity using MOPAC 3D Pro.     

Studies on structural and optical properties of pure and transition metals (Ni,Fe and co-doped Ni–Fe) doped tin oxide (SnO2) nanoparticles for anti-microbial activity

Research on Chemical Intermediates - In this present work, pure and transition metal ions (Ni, Fe and co-doped Ni–Fe) doped SnO2 nanoparticles (NPs) were synthesized using a simple chemical...     

Bursatella leachii Purple Ink Secretion Concentrate Exerts Cytotoxic Properties against Human Hepatocarcinoma Cell Line (HepG2): In Vitro and In Silico Studies

Liver cancer is a leading cause of cancer death globally. Marine mollusc-derived drugs have gained attention as potential natural-based anti-cancer agents to overcome the side effects caused by conventional chemotherapeutic drugs during cancer therapy. Using liquid chromatography-mass spectrometry, the main biomolecules in the purple ink secretion released by the sea hare, named Bursatella leachii (B. leachii), were identified as hectochlorin, malyngamide X, malyngolide S, bursatellin and lyngbyatoxin A. The cytotoxic effects of B. leachii ink concentrate against human hepatocarcinoma (HepG2) cells were determined to be dose- and time-dependent, and further exploration of the underlying mechanisms causing the programmed cell death (apoptosis) were performed. The expression of cleaved-caspase-8 and cleaved-caspase-3, key cysteine-aspartic proteases involved in the initiation and completion of the apoptosis process, appeared after HepG2 cell exposure to the B. leachii ink concentrate. The gene expression levels of pro-apoptotic BAX, TP53 and Cyclin D1 were increased after treatment with the B. leachii ink concentrate. Applying in silico approaches, the high scores predicted that bioactivities for the five compounds were protease and kinase inhibitors. The ADME and cytochrome profiles for the compounds were also predicted. Altogether, the B. leachii ink concentrate has high pro-apoptotic potentials, suggesting it as a promising safe natural product-based drug for the treatment of liver cancer.     

One pot facile hydrothermal synthesis of superparamagnetic ZnFe2O4 nanoparticles and their properties

Superparamagnetic ZnFe₂O₄ nanoparticles were synthesized by facile hydrothermal method using different amount of diethylamine (DEA) as a precipitating agent. The phase formation, morphological and magnetic properties were investigated using X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and vibrating sample magnetometer. The amount of DEA required for forming single phase ZnFe₂O₄ was optimized. For 2 ml of DEA, a mixed phase of α-Fe₂O₃ and ZnFe₂O₄ was formed whereas single phase of ZnFe₂O₄ was formed with high crystalline quality for 4, 6, 8 and 10 ml of DEA. FE-SEM results indicated that all the synthesized products were in spherical shape with small aggregations. Particle size of 9 nm was obtained from TEM image for sample synthesized using 10 ml of DEA. Superparamagnetic property was observed for the samples synthesized using 4, 6, 8, and 10 ml of DEA.     

Facile one-pot synthesis of a photo patternable anthracene polymer

A polycyclic aromatic compound, anthracene, was covalently connected through a methylene bridge via Friedel-Crafts alkylation reaction. Thus, a highly fluorescent anthracene polymer (PMAn) linked by a methylene unit was prepared in one step to produce a conjugated-nonconjugated spacer-type polymer through its reaction with chloromethyl methyl ether (CME) and FeCl₃ at 0 °C. The resultant polymer was soluble in organic solvents and showed significantly higher fluorescence (quantum yield = 0.80) compared to monomeric anthracene, 9-methylanthracene, in chloroform solution. Fluorescent thin films of PMAn as solid media were prepared with high film uniformity. The emission of the film was extinguished when the film was exposed to a UV source, due to the photodimerization of anthracene unit. A fluorescent gap electrode pattern was formed on the polymer film-forming average step depth of 8 nm and 14 nm, after 30 and 60 min irradiation with a UV light, respectively. The photo patternable fluorescent polymer afforded a convenient method of image formation and patterning.