Application of Fugacity Models to the Estimation of Chemical Distribution and Persistence in the Environment

The nanostructure and chemical distribution in semi-insulating polycrystalline oxygen-doped silicon (SIPOS) deposited on (001) Si and its isothermal transformation behavior at 900 °C were investigated by high resolution electron microscopy (HREM) and electron energy loss nanospectroscopy (EELS). The structure of the as-deposited film, which contained 15 at. % oxygen, was amorphous. No evidence for nanocrystalline second phases was found. It was similar in appearance to amorphous silicon. After annealing for 30 min at 900 °C in an inert environment (N2), a dispersion of small nanocrystals, identified as silicon by imaging, diffraction and EELS, formed in the amorphous SIPOS matrix, with a thin precipitate free zone (PFZ) adjacent to the Si substrate. The SIPOS matrix oxygen concentration increased to 36 at. % and the matrix remained amorphous after annealing. No other phases were observed in annealed specimens. Changes in Si–L near edge fine structure and low loss peaks in EELS spectra from SIPOS with increasing oxygen concentration indicated that it is a solid solution supersaturated with silicon. Microstructures indicated that the Si nanocrystals formed during a homogeneous precipitation reaction.

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Globular clusters and the evolution of their multiple stellar populations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315010546 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 328-333

Author(s):

W. Chantereau ◽

C. Charbonnel ◽

G. Meynet

Keyword(s):

Globular Clusters ◽

Main Sequence ◽

Chemical Properties ◽

Stellar Populations ◽

Chemical Compositions ◽

Low Mass Stars ◽

Sequence Band ◽

Low Mass ◽

Chemical Distribution ◽

Host Stars

AbstractOur knowledge of the formation and early evolution of globular clusters (GCs) has been totally shaken with the discovery of the peculiar chemical properties of their long-lived host stars. Therefore, the interpretation of the observed Colour Magnitude Diagrams (CMD) and of the properties of the GC stellar populations requires the use of new stellar models computed with relevant chemical compositions. In this paper we use the grid of evolution models for low-mass stars computed by Chantereau et al. (2015) with the initial compositions of second-generation stars as predicted by the fast rotating massive stars scenario to build synthesis models of GCs. We discuss the implications of the assumed initial chemical distribution on 13 Gyr isochrones. We build population synthesis models to predict the fraction of stars born with various helium abundances in present day globular clusters (assuming an age of 13 Gyr). With the current assumptions, 61 % of stars on the main sequence are predicted to be born with a helium abundance in mass fraction, Yini, smaller than 0.3 and only 11 % have a Yini larger than 0.4. Along the horizontal branch, the fraction of stars with Yini inferior to 0.3 is similar to that obtained along the main sequence band (63 %), while the fraction of very He-enriched stars is significantly decreased (only 3 % with Yini larger than 0.38).

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Critical Success Factors for SMEs in the UK Chemical Distribution Industry: The ‘Brexit’ Effect

Palgrave Studies in Cross-disciplinary Business Research, In Association with EuroMed Academy of Business - The Changing Role of SMEs in Global Business ◽

10.1007/978-3-030-45831-7_8 ◽

2020 ◽

pp. 155-177

Author(s):

Evripidis Lampadarios ◽

Niki Kyriakidou

Keyword(s):

Critical Success Factors ◽

Success Factors ◽

Critical Success ◽

Chemical Distribution ◽

The Uk

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Inhibitory Activity of 8 Alkaloids on P-gp and Their Distribution in Chinese Uncaria Species

Natural Product Communications ◽

10.1177/1934578x20973506 ◽

2020 ◽

Vol 15 (11) ◽

pp. 1934578X2097350

Author(s):

Yanan Gai ◽

Nannan Yang ◽

Jian Chen

Keyword(s):

High Performance ◽

Positive Control ◽

Inhibitory Effects ◽

Glycoprotein P ◽

Chromatography Analysis ◽

Chemical Content ◽

Polymerase Chain ◽

Chemical Distribution ◽

And Function ◽

Mcf 7

P-glycoprotein (P-gp) inhibition conduces to improving the ability of chemicals to cross through blood-brain barrier (BBB). The hook-bearing branch of Uncaria is used as a traditional herbal medicine for the treatment of hypertension, headache, stroke, and Alzheimer’s disease in recent years. In this study, the inhibitory effects of 8 alkaloids sourced from Uncaria plants on P-gp were evaluated. Meanwhile, the content of 8 alkaloids in 8 Chinese Uncaria species was quantified simultaneously by high-performance liquid chromatography analysis. Western blotting, real-time quantitative reverse transcription-polymerase chain reaction, and flow cytometry were used to evaluate the P-gp levels in MCF-7/adriamycin-resistant (ADR) cells. It was shown that hirsuteine and hirsutine, selected from 8 candidate alkaloids, could remarkably suppressed P-gp level and function in MCF-7/ADR cells when using Verapamil as positive control. By tracking their chemical distribution in 8 Chinese Uncaria species, we found that hirsuteine and hirsutine were much more abundant in Uncaria rhynchophylla and Uncaria hirsuta than in any other 6 species. And a chemical content profile of these alkaloids was plotted within 8 Chinese species.

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