The effect of annealing on the properties of optical waveguides

Thesis (B.S.) in Chemistry--University of Illinois at Urbana-Champaign, 1990.Includes bibliographical references (leaves 11-12)Microfiche of typescript. [Urbana, Ill.]: Photographic Services, University of Illinois, U of I Library, [1990]. 1 microfiche (20 frames): negative.s 1990 ilu n

Chemically modified electrodes as amperometric sensors in electroanalysis

The state and prospects in the development of new fields of electroanalytical chemistry, namely amperometric sensors based on chemically modified electrodes, are examined. The methods for the construction of these electrodes, the types of modifying agents, and the mechanisms of their response to substrates are discussed. The analytical possibilities of chemically modified electrodes, including amperometric biosensors based on them, in the solution of problems associated with ecology, medicine, and pharmacology are demonstrated. © 1992 IOP Publishing Ltd

Complex electrochemical and impedimetric evaluation of DNA damage by using DNA biosensor based on a carbon screen-printed electrode

DNA biosensor (DNA/SWCNT-COOH-CHIT/SPCE) composed of dsDNA adsorptive layer on a carboxylated single-walled carbon nanotubes-chitosan composite deposited at a commercial carbon based screen-printed electrode has been prepared and applied to a complex investigation of damage to DNA by the Fenton type cleavage agent (hydroxyl radicals formed in the mixture of Cu2+, H 2O2 and ascorbic acid) and copper(ii)-quercetin system in 0.1 M PBS pH 7.0 under aerobic conditions. The dsDNA damage detection is performed by using square-wave voltammetry (SWV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 × 10-7 M thioridazine and 1 × 10-3 M K4[Fe(CN) 6]/K3Fe(CN)6 in the 0.1 M phosphate buffer solution, pH 7.0. Initial enhancement of the intrinsic guanine and adenine moieties SWV response over that of original dsDNA one indicates opening of the helix structure in the first stage of damage. At the same time, decrease in the intercalated thioridazine response confirms damage of the helix structure in parallel to deep degradation of the DNA chain and its removal from the electrode surface as indicated by the CV and EIS measurements in the presence of the [Fe(CN)6]3-/4- redox indicator in solution. © 2011 The Royal Society of Chemistry

Biosensor with Protective Membrane for the Detection of DNA Damage and Antioxidant Properties of Fruit Juices

With the purpose to prepare a DNA biosensor protected with an outer-sphere membrane against high molecular weight interferences, a carbon film electrode was layer-by-layer modified with dsDNA and chitosan. Using cyclic and square-wave voltammetry and impedance spectroscopy, the oxidative damage of DNA by the hydroxyl and superoxide anion radicals was detected which consists of opening of the helix structure followed by deep DNA chain degradation. The biosensor has been applied to the detection of the antioxidant effect of apple and orange juices. The investigation of the novel biosensor with a protective membrane represents a significant contribution to the field of DNA biosensors utilization. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Developmental expression of SNAP-25 protein in the rat striatum and cerebral cortex

The developmental changes of 25-kDa synaptosomal-associated protein (SNAP-25) expression in the rat striatum and cerebral cortex were examined using Western- blotting and densitometric scanning of immunoblots. Analysis of the striatum extracts from postnatal day 0 (P0) to postnatal day 120 (P120) demonstrated that SNAP-25 is poorly expressed until P14. From this point the expression level gradually increases to reach a maximum on P60 and then decreases. The pattern of SNAP-25 expression in the rat cerebral cortex is different. Two peaks are observed, the first on P10 and the second on P60, after which the expression level decreases. These results appear to confirm the role of SNAP-25 protein in axon outgrowth and synaptogenesis in the nervous system

Disposable electrochemical biosensor with multiwalled carbon nanotubes - Chitosan composite layer for the detection of deep DNA damage

A novel electrochemical DNA-based biosensor for the detection of deep DNA damage was designed employing the bionanocomposite layer of multiwalled carbon nanotubes (MWNT) in chitosan (CHIT) deposited on a screen printed carbon electrode (SPCE). The biocomponent represented by double-stranded (ds) herring sperm DNA was immobilized on this composite using layer-by-layer coverage to form a robust film. Individual and complex electrode modifiers are characterized by a differential pulse voltammetry (DPV) with the DNA redox marker [Co(phen)3]3+, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with [Fe(CN)6]3- as a redox probe in a phosphate buffer solution (PBS). A good correlation between the CV and EIS parameters has been found, thus confirming a strong effect of MWNT on the enhancement of the electroconductivity of the electrode surface and that of CHIT on the MWNT distribution at the electrode surface. Differences between the CV and EIS signals of the electrodes without and with DNA are used to detect deep damage to DNA, advantageously using simple working procedures in the same experiment. 2008 © The Japan Society for Analytical Chemistry

Impedimetric nanostructured disposable DNA-based biosensors for the detection of deep DNA damage and effect of antioxidants

Novel impedimetric nanostructured disposable DNA-biosensors have been created using a layer of multiwalled carbon nanotubes (MWNT) and double stranded calf thymus or herring sperm DNA deposited on the surface of a screen-printed carbon electrode (SPCE) by layer-by-layer and mixed coverage. The presence of DNA significantly decreases the electroconductivity of the MWNT/SPCE interface and represents a charge barrier for the transport of the [Fe(CN6)]3- redox probe ions. Hence, electrochemical impedimetric procedure performed with DNA/MWNT/SPCE sensor in 0.1 M phosphate buffer solution (PBS) pH 7.0 using 1 mM [Fe(CN6)]3- was developed for the evaluation of deep DNA damage caused by reactive oxygen species formed in situ as well as antioxidative effects of rutin and tea extracts. Good correlation has been found between the charge transfer resistance change obtained as a parameter of the impedimetric equivalent circuit and the voltammetric current response change of the [Fe(CN6)]3- / [Fe(CN6)]4- redox couple measured at the DNA modified and bare SPCEs. © 2008 by ESG

Multi-seasonal systematic camera-trapping reveals fluctuating densities and high turnover rates of Carpathian lynx on the western edge of its native range

Camera-trapping and capture-recapture models are the most widely used tools for estimating densities of wild felids that have unique coat patterns, such as Eurasian lynx. However, studies dealing with this species are predominantly on a short-term basis and our knowledge of temporal trends and population persistence is still scarce. By using systematic camera-trapping and spatial capture-recapture models, we estimated lynx densities and evaluated density fluctuations, apparent survival, transition rate and individual's turnover during five consecutive seasons at three different sites situated in the Czech–Slovak–Polish borderland at the periphery of the Western Carpathians. Our density estimates vary between 0.26 and 1.85 lynx/100 km2 suitable habitat and represent the lowest and the highest lynx densities reported from the Carpathians. We recorded 1.5–4.1-fold changes in asynchronous fluctuated densities among all study sites and seasons. Furthermore, we detected high individual’s turnover (on average 46.3 ± 8.06% in all independent lynx and 37.6 ± 4.22% in adults) as well as low persistence of adults (only 3 out of 29 individuals detected in all seasons). The overall apparent survival rate was 0.63 ± 0.055 and overall transition rate between sites was 0.03 ± 0.019. Transition rate of males was significantly higher than in females, suggesting male-biased dispersal and female philopatry. Fluctuating densities and high turnover rates, in combination with documented lynx mortality, indicate that the population in our region faces several human-induced mortalities, such as poaching or lynx-vehicle collisions. These factors might restrict population growth and limit the dispersion of lynx to other subsequent areas, thus undermining the favourable conservation status of the Carpathian population. Moreover, our study demonstrates that long-term camera-trapping surveys are needed for evaluation of population trends and for reliable estimates of demographic parameters of wild territorial felids, and can be further used for establishing successful management and conservation measures

Intercalation of Hydrotalcites with Hexacyanoferrate(II) and (III)-a ThermoRaman Spectroscopic Study

Raman spectroscopy using a hot stage indicates that the intercalation of hexacyanoferrate(II) and (III) in the interlayer space of a Mg,Al hydrotalcites leads to layered solids where the intercalated species is both hexacyanoferrate(II) and (III). Raman spectroscopy shows that depending on the oxidation state of the initial hexacyanoferrate partial oxidation and reduction takes place upon intercalation. For the hexacyanoferrate(III) some partial reduction occurs during synthesis. The symmetry of the hexacyanoferrate decreases from Oh existing for the free anions to D3d in the hexacyanoferrate interlayered hydrotalcite complexes. Hot stage Raman spectroscopy reveals the oxidation of the hexacyanoferrate(II) to hexacyanoferrate(III) in the hydrotalcite interlayer with the removal of the cyanide anions above 250 °C. Thermal treatment causes the loss of CN ions through the observation of a band at 2080 cm-1. The hexacyanoferrate (III) interlayered Mg,Al hydrotalcites decomposes above 150 °C