Isolation and identification of new anthraquinones from Rhamnus alaternus L and evaluation of their free radical scavenging activity

From the butanolic and the ethyl acetate extracts of Rhamnus alaternus L root bark and leaves, three new anthraquinone glycosides, alaternosides A-C (1,4,6,8 tetrahydroxy-3 methyl anthraquinone 1-O-ß-D-glucopyranosyl-4,6-di-O-α-L-rhamnopyranoside (1); 1,2,6,8 tetrahydroxy-3 methyl anthraquinone 8-O-ß-D-glucopyranoside (2) and 1, 6 dihydroxy-3 methyl 6 [2′-Me (heptoxy)] anthraquinone (3)) were isolated and elucidated together with the two known anthraquinone glycosides, Physcion-8-O-rutinoside (4) and emodin-6-O-α-L-rhamnoside (5) as well as with the known kaempferol-7-methylether (6), β-sitosterol (7) and β-sitosterol-3-O-glycoside (8). Their chemical structures were elucidated using spectroscopic methods (1D-, 2D-NMR and FAB-MS). Free radical scavenging activity of the isolated compounds was evaluated by their ability to scavenge DPPH^. free radicals. Compounds (3), (4) and (6) showed the highest activity with IC₅₀ values of 9.46, 27.68 and 2.35 μg/mL, respectively.     

Entropy generation of nanomaterial through a tube considering swirl flow tools

Journal of Thermal Analysis and Calorimetry - The focus of the current investigation is on insertion of complex-shaped device for inducing swirl intensity. H2O-based copper oxide mixture was...     

Synthesis and applications of silver nanoparticles

Over the past few decades, nanoparticles of noble metals such as silver exhibited significantly distinct physical, chemical and biological properties from their bulk counterparts. Nano-size particles of less than 100 nm in diameter are currently attracting increasing attention for the wide range of new applications in various fields of industry. Such powders can exhibit properties that differ substantially from those of bulk materials, as a result of small particle dimension, high surface area, quantum confinement and other effects. Most of the unique properties of nanoparticles require not only the particles to be of nano-sized, but also the particles be dispersed without agglomeration. Discoveries in the past decade have clearly demonstrated that the electromagnetic, optical and catalytic properties of silver nanoparticles are strongly influenced by shape, size and size distribution, which are often varied by varying the synthetic methods, reducing agents and stabilizers. Accordingly, this review presents different methods of preparation silver nanoparticles and application of these nanoparticles in different fields.     

Small Iminocoumarin Derivatives as Red Emitters: From Biological Imaging to Highly Photoluminescent Non‐doped Micro‐ and Nanofibres

The fluorescence properties of four derivatives of 3‐thienyl‐2‐(N‐dicyanovinyl)iminocoumarin, bearing a diethylamino group in the 7‐position or a methoxy group in the 6, 7 and 8 positions, were compared in solution and in the solid state. The 7‐diethylamino derivative was strongly fluorescent in various solvents, with marked solvatochromism. Its fluorescence was quenched by aggregation. In contrast, the methoxy derivatives were only moderately or weakly fluorescent in solution, but two of them were strongly photoluminescent in the crystalline state, owing to favourable molecular packing. The 6‐methoxy derivative even exhibited spectacular crystallization‐enhanced emission, examples of which are particularly rare for this type of dyes. Dyes were tested for biological use. The 7‐diethylamino derivative led to particularly strong fluorescence staining of the cytoplasm of HCT‐116 colon cancer cells. No fading was observed over prolonged illumination by the microscope light beam, but a phototoxic effect was detected. The use of the dyes as red‐emitting materials was also investigated. Using easy‐to‐implement preparation methods, the compounds self‐ assembled to give one‐dimensional nano‐ and microsized particles, including millimeter‐long microfibres that exhibited clear wave‐guiding properties. This study shows the value of these low molecular‐weight molecules for the preparation of new orange and red‐emitting fluorescent materials based on totally pure dye.     

Engineering the surface properties of microfluidic stickers

We introduce a simple and effective method to tailor the wetting and adhesion properties of thiolene-based microfluidic devices. This one-step lithographic scheme combines most of the advantages offered by the current methods employed to pattern microchannels: (i) the channel walls can be modified in situ or ex situ, (ii) their wettability can be varied in a continuous manner, (iii) heterogeneous patterning can be easily accomplished, with contact-angle contrasts extending from 0 to 90° for pure water, (iv) the surface modification has proven to be highly stable upon aging and heating. We first characterize the wetting properties of the modified surfaces. We then provide the details of two complementary methods to achieve surface patterning. Finally, we demonstrate the two methods with three examples of applications: the capillary guiding of fluids, the production of double emulsions, and the culture of cells on adhesive micropatterns.     

Quasi-linear parabolic problems in L 1 with non homogeneous conditions on the boundary

We are interested in parabolic problems with L¹ data of the type

Sign‐changing bubble for Neumann problem with critical nonlinearity on the boundary

The main purpose of this paper is to construct sign‐changing solution for the following Neumann problem: where n≥3 and K is a bounded and continuous function on , which concentrate around two critical points satisfying some conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Amino acids in the syntheses of heterocyclic systems: Syntheses and radiostability of novel biologically active triazoles containing the sulfonamide moiety

A number of novel triazoles 2a–f, 4, 9, 10, 12, 15 ; triazolothiadiazoles 6, 8, 11, 16 ; triazolothiadiazine 5 ; and triazolotriazine 14 were synthesized and characterized by elemental analyses and spectral data. Six of the compounds showed antifungal activity compared with the fungicide Mycostatine. Radiosterilization of the biologically active compounds 4, 8, 9b , and 10 in the dry state may prove to be applicable at the sterile dose 25 kGy. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:316–323, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10037