Combined Characterization of Nanostructures by AEM and STM

Oleshko, Vladimir P.; Gijbels, R.; Jacob, W.; Алфимов, М. В.

doi:10.1007/978-3-7091-6555-3_36

Cited by 3 publications

(4 citation statements)

References 11 publications

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“…The rhodiola extract has become a recognized preparation, not less popular than the other well-known tonic phytopreparations based on ginseng, eleutherococcus, and magnolia vine. The currently important directions of investigation are, first, to extend the field of application of rhodiola preparations as antitumor and antiischemic remedies [25,26] and, second, to create more perfect medicinal forms and develop complex preparations [27,28].…”

Section: Rhodiola Rosea: Problems and Prospects Of Creating Preparatimentioning

confidence: 99%

Traditional and biotechnological aspects of obtaining medicinal preparations fromRhodiola Rosea L. (A review)

1999

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By now, there are about 300 medicinal plants successfully used in medical practice. Moreover, recent years showed a steady tendency for extending this class.Obtaining phytopreparations always involves extraction of the biologically active substances, followed by their separation and purification using various technological methods. One of the main negative factors, introducing instability in the manufacture of phytopreparations, is an irregular character of the supply of raw materials for their production. The reasons include, in particular, a sharp decrease in the natural stock of both wild-growing and cultivated medicinal plants.In connection with this, both the search for new medicinal plants and work on creation of a reliable stock of pharmacopoeial plants are of considerable practical value. Besides the traditional work on large-scale cultivation of medicinal plants, a highly promising direction is the biotechnological production of raw plant materials and related preparations.Biotechnology, which means carrying out technological processes with the aid of biological systems, has been rapidly developing in the past years and is recognized as a priority direction in the future scientific progress [ 1 -8].An important field of biotechnology is the growth of plant cells (or medicinal plant tissue cultures), in which the main difficulties are related to development of the necessary commercial equipment. This field is most extensively developed in Japan, where large-scale cultivation of plant cells was successfully realized many years ago (a 20-m 3 biomass reported in 1976) [1].From the standpoint of the commercial growth of cultures, the most efficient technology is that based on bulk cultivation (suspension cell culture). This method reduces the process time and minimizes manual operations as compared

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Section: Rhodiola Rosea: Problems and Prospects Of Creating Preparatimentioning

confidence: 99%

Traditional and biotechnological aspects of obtaining medicinal preparations fromRhodiola Rosea L. (A review)

1999

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“…Here D β β β β is the mass fractal dimension characterising a given population of aggregates. It is significant that at the early stages of aggregation clusters forming by the CPA mechanism contain a small number (100-300) of specks and therefore cannot be considered as fractals in the strict sense of the word [12]. In this case the parameter D β β β β describes the distribution of the substance in the system.…”

Section: Ag Colloidsmentioning

confidence: 99%

“…In the central part of the crystal, Ag filaments and particles formed branched web-like statistical networks. Generation of disordered aggregated structures by silver filaments and particles is obviously related to the stochastic nature of the development process in specific conditions, i.e., the local excess of the active volume developer and the high overpotential of the anode step of the reaction, the occurrence of both direct chemical and solution physical development mechanisms, and the presence of a protective polymer layer on the crystal surfaces [16]. Moreover, the obtained results suggest that the networks arise in some type of critical process, where such features as self-similarity, scaling and universality are displayed, and which, in principle, may be suitably described by percolation [17].…”

Section: Ag Colloidsmentioning

confidence: 99%

Study of Quasi-Fractal Many-Particle-Systems and Percolation Networks by Zero-Loss Spectroscopic Imaging, Electron Energy-Loss Spectroscopy and Digital Image Analysis

Oleshko

Kindratenko

Gijbels

et al. 1996

Microbeam and Nanobeam Analysis

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Abstract. Submicron colloidal Ag particles and nano-sized filaments forming a statistical percolation network during "in situ" development of double structure tabular microcrystals of AgBr(I) emulsions have been studied by electron energy-loss spectroscopy and zero-loss electron spectroscopic imaging (EELS/ ZLESI). Image analysis has shown that random quasi-fractal clusters were formed in the colloid. ZLESI has been applied to characterise the morphology and defect structure of aggregated particles and filaments. Their energy-loss spectra revealed plasmon excitations and interband 4d electron transitions between 4-32 eV energy-loss. To study the cluster structure and its relation to the physical properties, fractal analysis including estimations of cluster fractal dimensions and of density autocorrelation functions has been performed. Mechanisms of fractal aggregation based on known models of diffusion limited aggregation, cluster-cluster aggregation and percolation are discussed.

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“…Transmission electron microscopy 2 allows for the structure determination of individual crystals. With analytical electron microscopy, − electron energy loss spectroscopy, and electron spectroscopic imaging, local chemical analysis can be performed within individual microcrystals.…”

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confidence: 99%

Automated Particle Analysis of Populations of Silver Halide Microcrystals by Electron Probe Microanalysis under Cryogenic Conditions

Gregory¹,

Nullens²,

Gijbels³

et al. 1998

Anal. Chem.

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An automated particle analysis routine is implemented on an electron microprobe for analyzing the chemical composition and projective area of populations of individual silver halide microcrystals. An LN2 cryostage is used to prevent material degradation due to reaction with the impinging electron beam. The background in the EDX spectra is lowered by depositing the microcrystals on a carbon-coated copper grid, mounted in a transmission holder. The ILα/AgLα net X-ray intensity ratio, obtained from a spectrum-fitting algorithm, is used to determine the crystal composition by means of a standard-based calibration curve. The uncertainty on the concentration measurement of individual microcrystals is calculated using the uncertainties on the net X-ray counts and the uncertainties on the calibration curve. The area measurement is optimized by introducing a gray value histogram correction on each individual measurement. Overlapping microcrystals are scrapped from the analysis by defining a maximum shape factor, against which the shape factor of the microcrystal is tested. To minimize problems with drift of the cryostage, spectrum acquisition is carried out immediately after a single microcrystal has been located, based on the backscattered electron image. Several applications are discussed.

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Combined Characterization of Nanostructures by AEM and STM

Cited by 3 publications

References 11 publications

Traditional and biotechnological aspects of obtaining medicinal preparations fromRhodiola Rosea L. (A review)

Traditional and biotechnological aspects of obtaining medicinal preparations fromRhodiola Rosea L. (A review)

Study of Quasi-Fractal Many-Particle-Systems and Percolation Networks by Zero-Loss Spectroscopic Imaging, Electron Energy-Loss Spectroscopy and Digital Image Analysis

Automated Particle Analysis of Populations of Silver Halide Microcrystals by Electron Probe Microanalysis under Cryogenic Conditions

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