Determination of the Free Radical Scavenging Activity of Lycium Extracts

Lycium species growing in Turkey have not so far been studied sufficiently. For this reason, non-polar and polar extracts obtained from the fruits of Lycium barbarum L. and L. Ruthenicum Murray (Solanaceae) were assessed both in vitro for their potential as free radical scavenger crude extracts and their phenolic composition. Fruits of Lycium species were sequentially extracted with petroleum ether, ethyl acetate, methanol, n-butanol, and water in a Soxhlet extractor. All the extracts were assessed for the scavenging of the nitrogen-centered free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH^.) by in vitro method. Furthermore, the composition of each extract was investigated both in terms of its Folin-Ciocalteau reactive components and its qualitative content. The phenolic compounds within the extracts were determined as benzoic acid and hydroxycinnamic acid derivatives, flavonoids, and anthocyanins according to their retention time and UV spectral data by HPLC-DAD system.     

Addition of Al(OH)3 versus AlO(OH) nanoparticles on the optical,thermo-mechanical and heat/oxygen transmission properties of microfibrillated cellulose films

Cellulose - Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC),...     

Sol–gel derived LaFeO3/SiO2 nanocomposite: synthesis,characterization and its application as a new,green and recoverable heterogeneous catalyst for the efficient acetylation of amines,alcohols and phenols

LaFeO₃/SiO₂ nanocomposite was synthesized by the sol–gel process from metal nitrates and tetraethyl orthosilicate (TEOS) as the SiO₂ source. The nanocomposite product was characterized by XRD, FT-IR, SEM, and surface area measurements and was used as a heterogeneous catalyst for the efficient acetylation of amines, alcohols and phenols to the corresponding acetates using acetic anhydride under solvent-free conditions. Among the various substrates, acetylation of amines was preceded rapidly, so that an amine group could be selectively acetylated in the presence of alcoholic or phenolic hydroxyl groups by the appropriate choice of reaction time. The catalyst can also be reused several times without the loss of activity. In addition, the catalytic activity of the LaFeO₃/SiO₂ nanocomposite was higher than that of the pure LaFeO₃ nanoparticles. The method is high yielding, clean, cost effective, compatible with the substrates having other functional groups and very suitable for the practical organic synthesis.     

Antimicrobial properties of viscose yarns ring-spun with integrated amino-functionalized nanocellulose

Cellulose - Bio-based, renewable and biodegradable products with multifunctional properties are also becoming basic trends in the textile sector. In this frame, cellulose nanofibrils (CNFs) have...     

Enzymatic phosphorylation of cellulose nanofibers to new highly-ions adsorbing,flame-retardant and hydroxyapatite-growth induced natural nanoparticles

This study confirms the enzyme-mediated phosphorylation of cellulose nanofibers (CNF) by using hexokinase and adenosine-5′-triphosphate in the presence of Mg-ions, resulting in a phosphate group’s creation predominantly at C-6-O positioned hydroxyl groups of cellulose monomer rings. A proof-of-concept is provided using ¹²C CPMAS, ³¹P MAS nuclear magnetic resonance, attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) analyzing methods. The degree of substitution (DS) is determined by elemental analysis and compared to DS estimated by XPS analysis. From the thermal degradation measurements using thermo-gravimetric analysis, the C-6-O phosphorylation was found to noticeably prevent the CNF derivatives from weight loss in the pyrolysis process, thus, providing them flame-resistance functionality. Furthermore, phosphorylation significantly enhanced adsorption capacity of Fe³⁺ ions making them interesting for fabrication of biobased filters and membranes. Finally, the biomimetic growth of Ca–P crystals (hydroxyapatite) in simulated body fluid was characterized by scanning electron microscopy and energy dispersive X-ray, showing potential application as biomedical materials.     

ZnAl2O4 SiO2纳米复合催化剂用于无溶剂条件下乙酸酐与醇、酚和胺的乙酰化反应简

A ZnAl₂O₄@SiO₂ nanocomposite was prepared from metal nitrates and tetraethyl orthosilicate by the sol-gel process, and characterized by X-ray diffraction, Fourier transform infrared, transmission electron microscopy, and N₂ adsorption-desorption measurements. The nanocomposite was tested as a heterogeneous catalyst for the acetylation of alcohols, phenols, and amines under solvent-free conditions. Under optimized conditions, efficient acetylation of these substrates with acetic anhydride over the ZnAl₂O₄@SiO₂ nanocomposite was obtained. Acetylation of anilines and primary aliphatic amines proceeded rapidly at room temperature, while the reaction time was longer for the acetylation of alcohols and phenols, showing that an amine NH₂ group can be selectively acetylated in the presence of alcoholic or phenolic OH groups. The catalyst can be reused without obvious loss of catalytic activity. The catalytic activity of the ZnAl₂O₄@SiO₂ nanocomposite was higher than that of pure ZnAl₂O₄. The method gives high yields, and is clean, cost effective, compatible with substrates having other functional groups and it is suitable for practical organic synthesis.     

ZnAl_2O_4@SiO_2纳米复合催化剂用于无溶剂条件下乙酸酐与醇、酚和胺的乙酰化反应(英文)

A ZnAl2O4@SiO2 nanocomposite was prepared from metal nitrates and tetraethyl orthosilicate by the sol-gel process,and characterized by X-ray diffraction,Fourier transform infrared,transmission electron microscopy,and N2 adsorption-desorption measurements.The nanocomposite was tested as a heterogeneous catalyst for the acetylation of alcohols,phenols,and amines under solvent-free conditions.Under optimized conditions,efficient acetylation of these substrates with acetic anhydride over the ZnAl2O4@SiO2 nanocomposite was obtained.Acetylation of anilines and primary aliphatic amines proceeded rapidly at room temperature,while the reaction time was longer for the acetylation of alcohols and phenols,showing that an amine NH2 group can be selectively acetylated in the presence of alcoholic or phenolic OH groups.The catalyst can be reused without obvious loss of catalytic activity.The catalytic activity of the ZnAl2O4@SiO2 nanocomposite was higher than that of pure ZnAl2O4.The method gives high yields,and is clean,cost effective,compatible with substrates having other functional groups and it is suitable for practical organic synthesis.     

Benchmark approach to search of cost-effective and accurate density functional for homolytic cleavage of C─Mg bond of Grignard reagent

Grignard reactions are of importance in organic chemistry for the synthesis β-keto esters and diethyl malonate, alcohols, aldehydes or ketones, monocarboxylic acids, and other organometallic compounds. Generally, the heterolytic dissociation of C─Mg bond in Grignard reagent is the key step in these reactions. Recently, homolytic cleavage of the C─Mg bond in Grignard reagents has been reported in the preparation of stable radicals. These reactive species react with other compounds, which result in the formation of hydrocarbons and their derivatives. Therefore, the study of homolytic cleavage of C─Mg bonds is quite vital to better understand the kinetics and thermodynamics of these reactions. In the current study, a benchmark approach is adopted to find a cost-effective and accurate density functional (DF) for bond dissociation energies measurement of the C─Mg bond of Grignard reagents. Twenty-nine DFs from 13 density functional theory (DFT) classes with three types of basis sets (Pople' 6-31G(d) and 6-311G(d), Dunning's aug-cc-pVDZ, and Karlsruhe' def2-SVP basis sets) are implemented for the measurement of dissociation energies of the C─Mg bond. Theoretical dissociation energy values are compared with experimental reported values of the C─Mg bond of selected Grignard reagents. TPSSTPSS of the meta-GGA class with 6-31G (d) basis set gave accurate results, and its Pearson's correlation is 0.95. SD, root mean square deviation, and mean unsigned error of this method are 2.36 kcal mol⁻¹, 2.33 kcal mol⁻¹, and −0.46 kcal mol⁻¹, respectively. TPSSTPSS of the meta-GGA class is a one-electron, self-interaction, error-free Tao-Perdew-Staroverov-Scuseria functional that performed better with the 6-31G(d) basis set.     

Inverse scattering problem for Sturm–Liouville operator with nonlinear dependence on the spectral parameter in the boundary condition

The inverse problem of the scattering theory for Sturm–Liouville operator on the half line with boundary condition depending quadratic on the spectral parameter is considered. Scattering data are defined, some properties of the scattering data are examined, the main equation is obtained, solvability of the integral equation is proved and uniqueness of algorithm to the potential with given scattering data is studied. Copyright © 2010 John Wiley & Sons, Ltd.     

Localized radiative energy transfer from a plasmonic bow-tie nano-antenna to a magnetic thin film stack

TiO₂ nanotubes (NTs) are synthesized by anodization of a titanium foil in organic electrolytes, followed by thermal treatment in O₂ at different temperatures. These TiO₂ NTs exhibit visible-light photocatalytic activity which strongly depends on the formation of the thin surface carbon layer induced by dissociation of the electrolytes. Microstructural and spectral examinations suggest that the presence of the thin carbon layer and improved TiO₂ crystallinity achieved by annealing at a higher temperature conjointly lead to the enhanced photocatalytic activity. Our results disclose that the visible photocatalytic activity of TiO₂ NTs can be enhanced by using the appropriate electrolytes and thermal treatment conditions.