Search results for "Chen"

Natural and artificial radioactivity levels in Livingston Island (Antarctic regions).

1994

Radioactive contamination of the sea and land is due, on the one hand, to fallout from atmospheric atomic explosions since 1945, and, on the other, to emissions produced by nuclear and radioactive facilities. Given its geographic position far distant from the aforementioned main sources of radioactive contamination, Antarctica should have the lowest levels that can be measured on the Earth of artificial radionuclides in the various receptor media which are characteristic of the trophic chain. In the case of Antarctica, these are melt-water, sea-water, mosses, algae, and lichens. With the aim of contributing basic information on the radiation levels present in the Antarctic ecosystem, we hav…

The Eminent Russian – German Chemist Friedrich Konrad Beilstein (1838-1906) in the Literature between the 19th and 21st Centuries

2021

Friedrich Konrad Beilstein (1838-1906) was one of the most prominent chemists of the second half of the nineteenth century. His life and scientific achievements were described in the literature published between the 19th and 21st centuries in different countries. The purpose of this paper is to familiarize readers with the important events in the life of Beilstein and his research activities, in particular some of his experimental research results, as well as his selected publications. In addition, the names of authors of biographies or biographical notes about Beilstein, published in 1890-2018 are presented.

Linguistica Lettica, Nr. 1

1997

Hyperfine Paschen-Back regime realized in Rb nanocell

2012

A simple and efficient scheme based on one-dimensional nanometric thin cell filled with Rb and strong permanent ring magnets allowed direct observation of hyperfine Paschen-Back regime on D1 line in 0.5 - 0.7 T magnetic field. Experimental results are perfectly consistent with the theory. In particular, with sigma+ laser excitation, the slopes of B-field dependence of frequency shift for all the 10 individual transitions of 85,87Rb are the same and equal to 18.6 MHz/mT. Possible applications for magnetometry with submicron spatial resolution and tunable atomic frequency references are discussed.

Study of optical and magneto-optical processes in cesium, rubidium and potassium micro- and nano-metric thin atomic layers

2016

It has been investigated the D1 line transitions of 39K atoms in external magnetic fields using nanocells for the cases of sigma+ and pi polarizations of laser radiation. For the first time it is demonstrated the decoupling of electronic total angular momentum J and nuclear momentum I (complete hyperfine Paschen-Back regime) in external magnetic field. For 39K the decoupling takes place at B >> 165 G. In the case of linear polarization it is shown that for B > 400 G the transmission spectrum consists of 2 groups of transitions and each group contains of one so-called "Guiding transition" (GT). The GT indicates the asymptotic value of all transitions probabilities in the group and the freque…

Growth response of the saltbush Atriplex nummularia L. to inoculation with the arbuscular mycorrhizal fungus Glomus intraradices

2005

Abstract Plantlets of Atriplex nummularia were inoculated with the arbuscular mycorrhizal fungi Glomus intraradices in a pot experiment. Plants were grown in a low P soil. Highly significant growth response of a Chenopodiaceae was recorded for the first time. Mycorrhizal colonization of roots was well developed, internal hyphae and vesicles were observed, but not arbuscules. These observations suggest that arbuscules are not necessary to obtain significant growth stimulation from mycorrhizal inoculation. Atriplex nummularia is already used as forage crops, its high mycorrhizal dependency offers possibilities to develop this production and revegetation strategies.

Microbial Community Structure and Density Under Different Tree Species in an Acid Forest Soil (Morvan, France)

2005

Overexploitation of forests to increase wood production has led to the replacement of native forest by large areas of monospecific tree plantations. In the present study, the effects of different monospecific tree cover plantations on density and composition of the indigenous soil microbial community are described. The experimental site of "Breuil-Chenue" in the Morvan (France) was the site of a comparison of a similar mineral soil under Norway spruce (Picea abies), Douglas fir (Pseudotuga menziesii), oak (Quercus sessiflora), and native forest [mixed stand dominated by oak and beech (Fagus sylvatica)]. Sampling was performed during winter (February) at three depths (0-5, 5-10, and 10-15 cm…

Lichen used to assess nickel atmospheric dispersion, an example of New Caledonia Asbestos and best practices View project Atmospheric signature in ma…

2015

International audience; Fifteen epiphytic lichens, collected near an active nickel mine and along an East-West transect across New Caledonia island (South-West Pacific), were analyzed for their metal contents. The purpose is to evaluate atmospheric metal contamination and the impact of mining exploitation on the surroundings. The structure of the compositional dataset was explored using a covariance biplot. The score of the first principal component was used as a generic indicator to locally evaluate the degree of contamination. This study demonstrates that Ni, Co and Cr are highly concentrated in lichens near mining exploitation.

Stereoisomers of beta-methyl-gamma-octalactone. I. Quantification in brandies as a function of wood origin and treatment of the barrels

1995

International audience

Variation in the concentration of ellagitannins and cis- and trans-beta-methyl--octalactone extracted from oak wood (Quercus robur L., Quercus petrae…

1997

International audience