Rosehip extraction: Process optimization and antioxidant capacity of extracts

This article examines the extraction of rosehip to study the recovery of a number of compounds with antioxidant properties (polyphenols, flavonoids, and β-carotene). Two varieties of rosehip, cultivated and wild are used as raw material. A detailed study of the process kinetics at different operating conditions is carried out in order to determine appropriate processing parameters, which results in extracts with higher content of target compounds and higher antioxidant capacity. Data on the concentration of active components in the different parts of the fruit (skin, seeds, and pappi) are also obtained, which gives information about their distribution within the fruit. The comparison of wild and cultivated varieties demonstrates the better quality of the cultivated one. The results are useful for production of improved and enriched rosehip extracts with higher content of antioxidant substances that have proven beneficial effects on the human health.      

Thiophene ring formation during the interaction of alkylsulfenyl chlorides with esters of 3-methyl-1,2,4-pentatrienephosphonic acid

Dialkyl esters of 3-methyl-1,2,4-pentatrienephosphonic acid react with alkylsulfenyl chlorides to produce dialkyl esters of 2-thienylphosphonic acid.     

Metamagnetic DyAlO<Subscript>3</Subscript> nanoparticles with very low magnetic moment

Nanocrystalline dysprosium monoaluminate (DyAlO₃) has been synthesized by modified sol–gel method after sintering the precursor gel at 950 °C. The micro-structural features have been verified by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy. The XRD pattern confirms the formation of single-phase DyAlO₃; the average size of the nanoparticles is 50 nm. X-Ray photoelectron spectroscopy has been used to study the chemical composition and bonding in the samples. The binding energies of core-level electrons in Dy, Al and O in DyAlO₃ nanopowder have been found slightly shifted compared to the respective values of the same elements. Both AC and DC magnetic susceptibilities have been measured in the temperature range 2–300 K. Unusually low effective magnetic moment of Dy³⁺, μ_eff = 0.38, has been derived from the inverse magnetic susceptibility–temperature plot between 4 and 252 K. The Nèel temperature, T_N = 3.920 K and exchange interaction constant J/k = −1.74 K, have been also determined.     

Interference of secondary pions and time-space characteristics of their emission volume in π− p interactions at 40 GeV/c

The interference of positive and negative pions produced in π^? p interactions at 40 GeV/c is studied. It is shown that negative pions are emitted from larger distance than positive ones. The influence of resonance production on the size of pion emission volume is observed.     

Heterocyclizations of hydroxyketones with two‐coordinated (trimethylsilylamino)phosphines, (Me3Si)2N?PE?SiMe3

The reaction of two‐coordinated (trimethylsilylamino)phosphines (Me₃Si)₂N PE SiMe₃ 1 (E = N) and 2 (E = CH) with hydroxycarbonyl compounds proceeded with four‐ or five‐member heterocyclization to yield derivatives of oxaphosphetane, oxaphospholanes, and oxaphospholes. The reaction rate depends on the structure of hydroxyketones as well as on the type of the two‐coordinated phosphorus compound in accordance with the polarity of the P=N and P=C bonds. Thus, reaction was completed in 30 min in the case of the ortho carbonyl phenoxy derivatives with the phosphine 1 , but required 2 h in the case of the alkyl hydroxy carbonyls. All reactions with the phosphine 2 took about 24 h. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:413–417, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20033     

Dimethylsilylaminophosphane heterocyclization of isothiocyanates to diazaphosphole‐thiones through zwitterionic intermediates

Isothiocyanates react with Me₂P‐N(SiMe₃)₂ with elimination of (Me₃Si)₂S to give new structurally characterized heterocyclic diazaphosphole derivatives, and in one case the intermediate zwitterionic compound was isolated and structurally characterized. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:196–202, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20595