HPTLC and GC-MS for Separation and Identification of Eugenol in Plants

JPC – Journal of Planar Chromatography – Modern TLC - Samples of clove, nutmeg, and cinnamon have been extracted by maceration with ethanol for 24 h and with aqueous ethanol 48 h....     

Synthesis and stereochemistry of some new 1,3,5-tris(1,3-dioxan-2-yl)-benzene derivatives

The synthesis and the stereochemistry of new 1,3,5-tris(1,3-dioxan-2-yl)-benzene derivatives are reported. The anancomeric structure and the axial orientation of the aryl group with respect to all 1,3-dioxane rings, and the cis-trans isomerism of some of the compounds are revealed. The data are supported by NMR investigations and by the molecular structure of one compound determined by single crystal X-ray diffractometry.     

N‐Heterocyclic carbenes derived from imidazo‐[1,5‐a]pyridines related to natural products: synthesis,structure and potential biological activity of some corresponding gold(I) and silver(I) complexes

A series of Au(I) complexes ( 12 , 13 , 14 , 15 , 16 ) and Ag(I) complexes ( 17 , 18 , 19 , 20 ) derived from imidazo[1,5‐a]pyridin‐3‐ylidenes were synthesized from AuCl(SMe₂) or by reacting silver(I) acetate with 2,5‐dimethylimidazo[1,5‐a]pyridin‐2‐ium iodide or imidazo[1,5‐a]pyridin‐2‐ium salts, and were characterized using NMR spectroscopy, mass spectrometry and elemental analyses. In addition, the Au(I) complex 13 and the Ag(I) complex 19 were characterized using single‐crystal X‐ray diffraction. Using paclitaxel as a standard, all Au(I) and Ag(I) N‐heterocyclic carbene complexes were evaluated for their in vitro anti‐tumour activity against 12 cell lines using a monolayer cell survival and proliferation assay. The highest anticancer activity was found for complexes 15 , 13 and 14 with mean IC₅₀ values of 10.09, 10.42 and 12.28 μM, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

Mesomorphic Properties of Some Sitosteryl Esters

The mesomorphic properties of some esters formed by aromatic acids with β-sitosterol are reported. It is shown that para-substituted benzoates are compounds exhibiting enantiotropic cholesteric and some smectic mesophases. Connections between the clearing points of sitosteryl esters and their homologous cholesteryl derivatives are discussed.     

Photoconductive organic materials based on N-vinylcarbazole copolymers with higher alkenes as recording media in photonics

With the purpose to obtain novel photoconductive organic materials with improved complex of physical–mechanical properties and high sensitivity value, the possibility of N-vinylcarbazole copolymerization with higher alkenes was studied.The deposited films were 1.0–2.0 pm thin after drying in vacuum. The photosensitivity of the copolymer films is one order of magnitude greater than other carbazole containing copolymers. The investigation of spectral sensitivity was realized. Photosensitivity reaches its maximal value in 400–800 nm wave band.A photothermoplastic information registration medium was developed using synthesized copolymers. On the prepared photothermoplastic film, were recorded diffraction gratings with diffractional efficiency of 8–10% and resolution of 1000 mm⁻¹, using electrophotographic method. Photographical sensitivity of obtained films allows real time (1–3 s) photographical and holographic image recording.     

Lanthanum zirconate nanoparticles and ceramics produced using a nitrate-modified alkoxide synthesis route

Fine lanthanum zirconate powder was prepared by thermally decomposing a nitrate-alkoxide-based precursor derived from dehydrated lanthanum nitrate, zirconium n-butoxide and 2-methoxyethanol. Upon heating, the decomposition of the organic groups was promoted by the nitrate groups, yielding a porous powder that crystallized into a pyrochlore phase at 800 °C. The powder that was heat treated at 900 °C for 1 h was composed of friable agglomerates of approximately 60-nm-sized nanoparticles. The ceramics obtained from the powder heat treated at 900 °C and milled for 30 min reached a relative density of 97.9 % after sintering at 1,400 °C for 10 h, which is at least 100 °C lower than the typically reported temperatures for this material.     

General Convergence Analysis of Stochastic First-Order Methods for Composite Optimization

Journal of Optimization Theory and Applications - In this paper, we consider stochastic composite convex optimization problems with the objective function satisfying a stochastic bounded gradient...     

Thermal analysis of Romanian ancient ceramics

The present work is focused on thermoanalytical investigations as thermogravimetric analysis (TG) and derivative thermal analysis (DTG), applied for the characterization of some samples collected from archaeological sites (Brasov and Trofeum Traiani) located in different regions of Romania. New informations derived about ceramic technologies concerning raw materials and binding materials (mineralogical components) have been obtained. All these experimental results have been correlated with related techniques as X-ray diffraction (XRD), energy-dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma—atomic emission spectrometry (ICP-AES). By progressive heating in static air atmosphere and in the temperature range of 20–800 °C, all investigated materials exhibit three main successive processes, associated with the dehydration and thermo-oxidative degradations. The rate of the first thermooxidative process, temperatures corresponding to the maximum rate of the second thermooxidative process and shrinkage temperature were associated with the damage of the investigated materials due to environmental impact. Heating also affects the contact between the fine-sized clay matrix and mineral clast fragments, appearing in reaction rims, sometimes showing newly formed phases. The temperature at which ancient ceramics and pottery were fired varies over a wide range (600–800 °C) depending on the type of clay used, although firing temperatures not above 30–400 °C have also been suggested. Clay minerals, as the main material for production of ceramics and pottery, show some characteristic reactions (dehydroxylation, decomposition, transformation) in the course of firing (heating effects) and several thermoanalytical criteria can be used for reconstruction of former production conditions.