Chemical characterization and bioactivities of polysaccharides from Apocynum venetum leaves extracted by different solvents

2019 ◽  
Vol 14 (1) ◽  
pp. 244-253 ◽  
Author(s):  
Jinhui Zhou ◽  
Ping Zou ◽  
Changliang Jing ◽  
Zongchang Xu ◽  
San Zhou ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Apocynum Venetum

The Possibilities for Analytical Methods in Photoemission and Low-Energy Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 348-349
Author(s):  
Ernst Bauer
Keyword(s):  
Chemical Characterization ◽  
Emission Angle ◽  
Relative Energy ◽  
Objective Lens ◽  
Chemical Information ◽  
Magnetic Lens ◽  
Incident Intensity ◽  
X Ray ◽  
Leed Pattern ◽  
Image Position

One of the major shortcomings of conventional PEEM and of LEEM is the lack of chemical information about the surface. Although the imaging of the LEED pattern in the back focal plane of the objective lens of a LEEM instrument allows chemical characterization via the crystalline structure derived from the LEED pattern, this method fails in the absence of a characteristic LEED pattern. Direct information about the atomic composition of the surface is then needed which can be best obtained from inner shell electrons either directly by x-ray-induced photoemission (XPEEM) or by x-ray- or electron-induced Auger electron emission (AEEM). These modes of excitation and imaging can be combined with conventional PEEM and LEEM in one instrument which is presently being developed. Thus a complete structural and chemical characterization becomes possible in one instrument, with parallel detection and high resolution.In contrast to LEEM, in which up to more than 50% of the incident intensity is available for image formation, the intensity of the emitted electrons is much lower in XPEEM and AEEM and the signal is much lower than the background in AEEM. Therefore, intensity I and resolution d have to be optimized simultaneously which is best done by maximizing Q = I/d2 with respect to maximum emission angle α and relative energy distribution ε = ΔVo/V accepted by the instrument. For a well-designed magnetic lens section of the cathode lens its aberrations are determined by the accelerating field F in front of the specimen. For a homogeneous accelerating field F and a cosine emission distribution one obtains for the optimum α and ε values αo,εo a radius of the minimum disc of confusion of

Olfactory and Chemical Characterization of Indoor Air-Towards a Psychophysical Model for Air Quality

1981 ◽  
Author(s):  
Birgitta Berglund ◽  
Ulf Berglund ◽  
Thomas Lindvall ◽  
Helene Nicander-Bredberg
Keyword(s):  
Air Quality ◽  
Indoor Air ◽  
Chemical Characterization

PURIFICATION AND PARTIAL CHEMICAL CHARACTERIZATION OF SHEEP NEUROPHYSIN

1973 ◽  
Vol 74 (2) ◽  
pp. 226-236 ◽  
Author(s):  
Michel Chrétien ◽  
Claude Gilardeau
Keyword(s):  
Amino Acid ◽  
Polyacrylamide Gel Electrophoresis ◽  
Chemical Characterization ◽  
Terminal Amino Acid ◽  
Amino Acid Determination ◽  
Pituitary Glands ◽  
Terminal Amino ◽  
Partial Chemical ◽  
Acid Determination

ABSTRACT A protein isolated from ovine pituitary glands has been purified, and its homogeneity assessed by NH2- and COOH-terminal amino acid determination, ultracentrifugation studies, and polyacrylamide gel electrophoresis after carboxymethylation. Its chemical and immunochemical properties are closely similar to those of beef and pork neurophysins, less similar to those of human neurophysins. It contains no tryptophan (like other neurophysins) or histidine (like all except bovine neurophysin-I and human neurophysins). It has alanine at the NH2-terminus and valine at the COOH-terminus. Its amino acid composition is similar to, but not identical with those of porcine and bovine neurophysins.

Laboratory Methods for the Physico-Chemical Characterization of Recombinant Allergens as Reference Standards

Alergologia ◽  
2020 ◽  
Vol 1 (4) ◽  
pp. 7
Author(s):  
Mariana Vieru ◽  
Florin-Dan Popescu ◽  
Laura Haidar ◽  
Carmen Bunu-Panaitescu
Keyword(s):  
Chemical Characterization ◽  
Reference Standards ◽  
Recombinant Allergens ◽  
Laboratory Methods ◽  
Physico Chemical

PHYTOCHEMICAL SCREENING, ANTIOXIDANT, ANTI-CYTOTOXIC AND ANTICANCER EFFECTS OF GALINSOGA PARVIFLORA AND VERNONIA POLYANTHES (ASTERACEAE) EXTRACTS

2020 ◽  
Vol 8 (10) ◽  
pp. 84-98
Author(s):  
Sula M. V. Feleti ◽  
Renê L. Aleluia ◽  
Suiany V. Gervásio ◽  
Jean Carlos V. Dutra ◽  
Jessica R. P. Oliveira ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Phenolic Acids ◽  
Unsaturated Fatty Acids ◽  
Biological Effects ◽  
Human Lymphocytes ◽  
Chemical Characterization ◽  
Total Content ◽  
Ags Cells ◽  
Ft Icr Ms ◽  
Ft Icr

The study was designed to investigate the chemical composition and the biological effects of G. parviflora and V. polyanthes ethanolic extracts in vitro. Total content of phenols, flavonoids and tannins was quantified by spectrophotometry; chemical characterization was permed by mass spectrometry (ESI (-) FT-ICR MS and APCI (+) FT-ICR MS analysis). Antioxidant activities were determined by FRAP and Fe2+ chelating methods. Extracts cytotoxicity was evaluated in human lymphocytes, sarcoma-180 (S-180) and human gastric adenocarcinoma (AGS) cells, by MTT assay. V. polyanthes presented higher total content of tannins and G. parviflora presented higher amount of phenols and flavonoids. Chemical characterization showed the presence of flavonoids, phenolic acids and sesquiterpene lactones in V. polyanthes extract, and steroids, phenolic acids and fatty acids (Poly Unsaturated Fatty Acids - PUFA) in G. parviflora extract. V. polyanthes extract stood out in the Fe2+ chelation test. G. parviflora extract did not present outstanding antioxidant results in the tested protocols. Both species showed a tendency to promote cytotoxicity in human lymphocyte cells. Regarding the antiproliferative effect, both species were able to reduce S-180 cell viability and G. parviflora extract showed high antiproliferative potential in the assay with AGS cells. These findings reinforce the medicinal use of these plants, as well as suggest their potential use for the development of new drugs and for the treatment of cancers.

Two Early Helladic II terracotta rollers from Asine and their glyptic context

2018 ◽  
Vol 11 ◽  
pp. 81-96
Author(s):  
Michael Lindblom ◽  
Gullög Nordquist ◽  
Hans Mommsen
Keyword(s):  
Bronze Age ◽  
Chemical Characterization ◽  
Early Bronze Age ◽  
The Third ◽  
Archaeological Perspective

Two Early Helladic II terracotta rollers from the Third Terrace at Asine are presented. The objects, used to impress relief decoration on pithoi and hearths, are unique in that no other examples are known from the Early Bronze Age Aegean. Their origin is discussed based on chemical characterization and their depositional contexts are reviewed from an archaeological perspective. Although there are no known impressions from these rollers on pithoi and hearths at Asine, it is shown that their owners surrounded themselves with different objects featuring similar glyptic impressions. Two such impressions find identical parallels at Tiryns and the combined evidence strongly suggest that Asine was the home for one or several potters who produced Early Helladic impressed hearths and pithoi.

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