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W pracy przedstawiono wyniki badań nad wpływem formy chemicznej związków cyny i ołowiu na ich dostępność dla korzeni kukurydzy oraz ich aktywność antymitotyczna. Badania prowadzono w warunkach laboratoryjnych przy ograniczonym życiu mikrobiologicznym. Stwierdzono, że czynnikiem decydującym o dostępności badanych związków dla korzeni kukurydzy jest ich lipofilowość, stopień dysocjacji oraz rodzaj i wielkość tworzonych przez nie jonów. W trakcie przemieszczania się badanych związków z podłoża do rośliny nie następuje zmiana ich struktury chemicznej. Badane związki ołowiu są bardziej fitotoksyczne i bardziej dostępne dla korzeni kukurydzy niż ich cynowe analogi. Z porównania działania antymitotycznego analogicznych trójalkilopochodnych cyny i ołowiu wynika, że pochodne ołowiowe są bardziej aktywne niż ich cynowe analogi.
The interaction of nanotechnology and biosciences opens the possibility for a wide variety of biological research topics and day-to-day applications at the molecular and cellular level. In particular, nanotechnology has been revolutionizing the area of biosensor. Nanobiosensor, an integration of physical sciences, molecular engineering, biology, chemistry and biotechnology holds the possibility of detecting and manipulating atoms and molecules using nanodevices, which have the potential for a wide range of both industrial and domestic applications. The role of electrochemical nanobiosensor in food analysis is an important and interesting area. This review covers the basic principles and types of electrochemical biosensor formats, role of nanomaterials for biosensor and reported food-specific applications of electrochemical nanobiosensors.
The aim of this review is to introduce some principle areas of biosensor research and illustrate current technology with selected examples, including physico-chemical transducers and biological materials used for analytical active layers.
This paper presents the results of study on the toxic action mechanism of organic derivatives of tin (IV) on black lipid membrane (BLM) as a model of cell membrane. Trimethyltinchloride, tripropyltinchloride, tributyltinchloride, triphenyltinchloride, dimethyltindichloride, dipropyltinchloride, dibutyltin- dichloride, diphenyltindichloride were tested. The compounds were selected to determine the role of their structural elements in the mechanism studied. The measurements were made for the concentrations of investigated compounds ranging from 0 to 12x 10-7 mol/L, i.e. within the range of toxic concentrations, causing the BLM depolarisation. The effects of compounds studied on BLM were strongly dependent on their concentration and structure, which the trans- membrane-potential measurements of model-membrane depolarisation (dynamics and extent) showed the most evidently. The efficiency of the interaction between the black lipid membrane and the tin (IV) derivatives increased as follows: dialkyl > trialkyl > diphenyl > triphenyl. The compounds studied were recognised as having the lipophilic properties-crucial for modification of model and biological membranes.
The effect of triphenyllead chloride on membrane potential and electrical conductance of internodal cells of the alga Nitellopsis obtusa was studied. It was found that the compound studied, when present at 50 μM concentration, caused membrane depolarization and increased electrical conductance. The effect is, however, observed only after 0-30 min incubation, which may be due to the cumulation of triphenyllead in the cell wall before direct contact with the plasma membrane could occur. After 30 min incubation in triphenyllead solution the average relative changes in the membrane potential and electric conductance were -0.1±0.04 and 0.33±0.08 (n=12), respectively. These changes may be due to increased permeability of chloride ionsbrought about by the compound's interaction with channel proteins, or increased unspecific leakage of ions induced by a disturbance in the membrane structure.
X-ray photoelectron spectroscopy was used to characterize the chemical species of lead in bryophyte and pebble samples obtained in a stream passing through a lead mine in England. The 4f7/2 photoelectron binding energy of lead in the three bryophytes agreed fairly well with each other, but differed from the binding energies for the mineral phases, where lead exists as sulfide, and possibly also sulfate and Pb2+ion bound to silicate.
The micro gold electrode modified by thiol layer was used as a working electrode in the cyclic voltammetry method. This analytical system was used for determining the neutral smell compounds: geraniol and coumarin. The decrease in reduction current value of [Fe(CN)6]-3 ions was observed already at the concentration of 10-5 M of the compound investigated. The dimensions of these changes were different for each compound and their discrimination by the above sensor was possible.
The presence of highly toxic acrylamide in food products such as fried potatoes and chips was confirmed by Swedish scientists from the Stockholm University. Neurotoxicity of this compound and its metabolites imposes a duty to control it by qualitative and quantitative assays. Recent findings showed that acrylamide is formed in heat-treated foods rich in asparagine and reducing sugars such as glucose. Exposing acrylamide to pH extremes results in its hydrolysis to acrylic acid and ammonia. The main objective of the work presented is the development of a new electrochemical sensor for the determination of acrylic acid in the presence of asparagine and acrylamide. We report on an intramolecular ion-channel sensor using self-assembled monolayers deposited onto gold electrodes. Macrocyclic polyamine molecules with long alkyl chains were adsorbed into the monolayer of 1-dodecanethiol on the gold surface. The signal generated due to the formation of a supramolecular complex between host and acrylic acid guest at the electrode interface was measured by Osteryoung square wave voltammetry (OSWV) with [Ru(NH3)6]3+ as an electroactive marker.
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