Search results for "Chen"

Modelling phase transition kinetics of chenodeoxycholic acid with the Runge–Kutta method

2009

Abstract The phase transition kinetics of two chenodeoxycholic acid polymorphic modifications— form I (stable at high temperature), form III (stable at low temperature) and the amorphous phase has been examined under various conditions of temperature and relative humidity. Form III conversion to form I was examined at high temperature conditions and was found to be non-spontaneous, requiring seed crystals for initiation. The formation kinetic model of form I was created incorporating the three-dimensional seed crystal growth, the phase transition rate proportion to the surface area of form I crystals, and the influence of the amorphous phase surface area changes with an empirical stage poin…

Idiome mit dem Lexem 'hand' im schwedisch-deutschen Idiomwörterbuch Hinter schwedischen Gardinen

2008

Polyphasic taxonomy of a novel yeast isolated from antarctic environment; description of Cryptococcus victoriae sp. nov.

1999

In 1992 some samples of mosses, lichens and soils were collected from Botany Bay, Southern Victoria Land (77 degrees 01' S 162 degrees 32' E) and, as a result of a routine screening programme some yeasts were isolated. One of them, designated as strain G5, showed marked differences when compared to other antarctic yeasts. According to morphological and physiological characteristics, we were able to identify the strain G5 as a yeast belonging to the genus Cryptococcus. Some characteristics of this genus are the growth response to myo-inositol, celobiose, raffinose and D-glucuronate, no-fermentation, the absence of mycelium and pseudomycelium, asexual reproduction, Diazolium blue B test (DBB)…

Phylogeny and ecological diversification of South African Sarcocornia (Chenopodiaceae)

2007

Molecular analysis of lichen-associated bacterial communities

2006

The bacterial communities associated with 11 different lichen samples (belonging to eight different species) from different habitats were investigated. The culturable aerobic-heterotrophic fraction of the bacterial communities was isolated from nine lichen samples on protein-rich and sugar-rich/N-free media. Thirty-four bacterial isolates were purified and pooled into groups (phylotypes) by analysis of the ribosomal internal transcribed spacer polymorphism. Twenty five phylotypes were identified, each comprising between one and three isolates. One isolate of each phylotype was partially sequenced and the resulting 16S rRNA gene sequences were compared in a phylogenetic analysis. Three gener…

Limited preparation contextuality in quantum theory and its relation to the Cirel'son bound

2015

Kochen-Specker (KS) theorem lies at the heart of the foundations of quantum mechanics. It establishes impossibility of explaining predictions of quantum theory by any noncontextual ontological model. Spekkens generalized the notion of KS contextuality in [Phys. Rev. A 71, 052108 (2005)] for arbitrary experimental procedures (preparation, measurement, and transformation procedure). Interestingly, later on it was shown that preparation contextuality powers parity-oblivious multiplexing [Phys. Rev. Lett. 102, 010401 (2009)], a two party information theoretic game. Thus, using resources of a given operational theory, the maximum success probability achievable in such a game suffices as a \emph{…

Contribution of isotopic geochemistry to the origin of lead in the atmosphere of Sicily.

2001

Air quality can be assessed using mineral and biological indicators: airborne particulate matter, mosses, lichens, and pine needles. However, the origin of the pollutant is usually difficult to determine on the sole basis of concentrations, particularly when many sources are involved. In this study, we report some examples of application of lead isotopic geochemistry on airborne particulate matter, lichens and pine needles as a mean to decipher sources of lead pollution in Sicily. Furthermore, we evaluate the use of Pb/Sc and Pb/Br ratios to enhance the discriminating power of the isotopic method. Besides the methodological aspect, this work aims to provide, at least for lead, a summary of …

Pb-210 isotope as a pollutant emission indicator= Izotop Pb-210 jako znacznik emisji zanieczyszczeń

2015

Abstract Passive biomonitoring using 210Pb was used in the paper to evaluate pollutant deposition. Well-developed epiphytic foliose lichens Hypogymnia physodes growing on spruce branches were used in the studies. The samples of mosses Pleurozium schreberi and soil (raw humus) were collected from the area around the tree from which the samples of lichens were collected. The studies have shown that it is possible to identify dust emission sources using a radioactive lead isotope (210Pb). The highest activity of 210Pb was observed in areas with increased deposition of other pollutants, such as Ni, Cd, Cu and Pb, which may indicate that 210Pb is one of the emission components

Origin of atmospheric lead in Johannesburg, South Africa

2006

International audience; The origin of lead in the atmosphere of Johannesburg, South Africa was investigated on the basis of elemental and lead isotopic analyses of coals, mine dumps, gasoline, and about 30 epiphytic lichen samples. Lead predominantly comes from automotive exhausts in urban and suburban areas, as leaded antiknock additives were still in use in South Africa at the time of the study. Although dust emissions from the numerous mine-tailing dumps were expected to contribute significantly to the heavy metal budget, the southern townships that are surrounded by the dumps (such as Soweto and other historically Black residential areas) do not appear to be more than partially influenc…

Perturbation vectors to evaluate air quality using lichens and bromeliads: a Brazilian case study.

2017

10 pages; International audience; Samples of one lichen species, Parmotrema crinitum, and one bromeliad species, Tillandsia usneoides, were collected in the state of Rio de Janeiro, Brazil, at four sites differently affected by anthropogenic pollution. The concentrations of aluminum, cadmium, copper, iron, lanthanum, lead, sulfur, titanium, zinc, and zirconium were determined by inductively coupled plasma-atomic emission spectroscopy. The environmental diagnosis was established by examining compositional changes via perturbation vectors, an underused family of methods designed to circumvent the problem of closure in any compositional dataset. The perturbation vectors between the reference s…