The development of political science in Central and Eastern Europe : bibliometric perspective, 1996–2013

This research aims to develop a deeper insight into the development of political science from the bibliometric perspective by analysing peer-reviewed journal articles (n = 1117) indexed in the Scopus database and published by authors from fifteen Central and Eastern European (CEE) countries in the period 1996–2013. Results indicate that the majority of articles (84%) by CEE authors have been published in international journals and in the English language. The visibility of these articles in international journals, measured by the mean number of citations, is 5.2 per paper, while the same indicator for CEE journal articles amounts to 0.2. Authorship analysis indicates a gradual but continuous increase in co-authorships. Additionally, there are significant differences in citations between single-authored and co-authored articles, both in international and CEE journals. Co-authorship among CEE authors is present in only 1% of the analysed articles, confirming weak collaboration between political scientists in CEE countries

Carbon film electrodes for oxidase-based enzyme sensors in food analysis

Carbon film resistor electrodes have been evaluated as transducers for the development of multiple oxidase-based enzyme electrode biosensors. The resistor electrodes were first modified with Prussian Blue (PB) and then covered by a layer of covalently immobilized enzyme. Electrochemical impedance spectroscopy was used to characterize the interfacial behaviour of the Prussian Blue modified and enzyme electrodes; the spectra demonstrated that the access of the substrates is essentially unaltered by application of the enzyme layer. These enzyme electrodes were used to detect the substrate of the oxidase (glucose, ethanol, lactate, glutamate) via reduction of hydrogen peroxide at +50 mV versus Ag/AgCl in the low micromolar range. Response times were 1-2 min. Finally, the glucose, ethanol and lactate electrochemical biosensors were used to analyse complex food matrices--must, wine and yoghurt. Data obtained by the single standard addition method were compared with a spectrophotometric reference method and showed good correlation, indicating that the electrodes are suitable for food analysis.http://www.sciencedirect.com/science/article/B6THP-4GNTFGP-2/1/087dc22044a84cfb2a1badf317934bc

Synthesis, characterization and influence of poly(brilliant green) on the performance of different electrode architectures based on carbon nanotubes and poly(3,4-ethylenedioxythiophene)

Brilliant green (BG), which belongs to the triphenylmethane family, has been electrochemically polymerised by cyclic voltammetry on bare carbon film electrodes (CFE) and for the first time on carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT) modified CFE. The modified electrodes have been characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in order to establish the position importance and the individual role of each component (CNT, PEDOT and PBG) in the overall electrode performance. The analytical performances of different electrode architectures towards hydrogen peroxide detection allowed the choice of the best electrode configuration for further application of the newly developed electrodes for sensor and biosensor construction

Novel Amperometric Mercury-Selective Sensor Based on Organic Chelator Ionophore

A novel amperometric sensor for the direct determination of toxic mercury ions, Hg2+, based on the organic chelator ionophore N, N di (2-hydroxy-5-[(4-nitrophenyl)diazenyl]benzaldehyde) benzene-1,2-diamine (NDBD), and multiwalled carbon nanotubes (MWCNT) immobilized on a glassy carbon electrode surface was developed. The parameters influencing sensor performance including the ionophore concentration, the applied potential, and electrolyte pH were optimized. The sensor response to Hg2+ was linear between 1-25 µM with a limit of detection of 60 nM. Interferences from other heavy metal ions were evaluated and the sensor showed excellent selectivity towards Hg2+. The method was successfully applied to the determination of mercury ions in milk and water samples

HYSTERESIS OF CONTACT ANGLE. DYNAMIC WETTABILITY STUDIES OF COLLAGEN AND DOXYCYCLINE POROUS MATRICES CROSSLINKED WITH TANNIC ACID

Collagen porous matrices are promising delivery systems which offer the possibility to obtain a local optimized drug release. One important prerequisite in understanding the drug dissolution profile is an adequate monitoring of the porous collagen matrices surface properties and surface wettability degree. In this study we have considered direct measurements of the contact angle and hysteresis of contact angle (dynamic contact angle) for some collagen matrices with doxycycline, cross-linked with tannic acid, in order to better describe the wettability properties of these drug release systems. The matrices were obtained by freeze-drying of collagen gels (the release support) which have embedded doxycycline as model drug. These systems were prepared at pH=3.8, and crosslinked with different concentrations of tannic acid (4%, 5%, 10%, respectively 20%). We also took into account in the study an uncrosslinked matrix (without tannic acid) as control sample. A KSV Instrument CAM 101 equipped with a digital camera and the pendant drop method were used for contact angle and surface properties experiments. The liquid (water) is imbibed into the porous matrices producing the contact angle decrease in time. The Young-Laplace equation was applied and the contact angle hysteresis was evaluated (difference between the maximum and the minimum contact angle values) to characterize the surface wettability and hydrophobicity

Optimization of Polyamide Pulp-Reinforced Silica Aerogel Composites for Thermal Protection Systems

The present work describes for the first time the preparation of silica-based aerogel composites containing tetraethoxysilane (TEOS) and vinyltrimethoxysilane (VTMS) reinforced with Kevlar® pulp. The developed system was extensively investigated, regarding its physical, morphological, thermal and mechanical features. The obtained bulk density values were satisfactory, down to 208 kg·m-3, and very good thermal properties were achieved-namely a thermal conductivity as low as 26 mW·m-1·K-1 (Hot Disk®) and thermal stability up to 550 °C. The introduction of VTMS offers a better dispersion of the polyamide fibers, as well as a higher hydrophobicity and thermal stability of the composites. The aerogels were also able to withstand five compression-decompression cycles without significant change of their size or microstructure. A design of experiment (DOE) was performed to assess the influence of different synthesis parameters, including silica co-precursors ratio, pulp amount and the solvent/Si molar ratio on the nanocomposite properties. The data obtained from the DOE allowed us to understand the significance of each parameter, offering reliable guidelines for the adjustment of the experimental procedure in order to achieve the optimum properties of the studied aerogel composites

Development of electrochemical biosensors based on sol-gel enzyme encapsulation and protective polymer membranes

Abstract Protective polymer coatings have been used to enhance the retention of enzymes in sol-gel films as immobilisation phases in electrochemical biosensors. Carbon film electrodes were electrochemically modified with poly(neutral red) (PNR). These electrodes were coated with oxysilane sol-gels incorporating glucose oxidase and an outer coating of carboxylated PVC (CPVC) or polyurethane (PU), with and without Aliquat-336 or isopropyl myristate (IPM) plasticizer, was applied. The biosensors were characterised electrochemically using cyclic voltammetry and amperometry, electrochemical impedance spectroscopy and scanning electron microscopy. Impedance spectra showed that the electrode surface is most active when the sol-gel–GOx layer is not covered with a membrane. However, membranes without plasticizer extend the lifetime of the biosensor to more than 2 months when PU is used as an outer membrane. The linear range of the biosensors was found to be 0.05–0.50 mM of glucose and the biosensor with PU outer membrane exhibited higher sensitivity (ca.117 nA mM-1) in the region of linear response than that with CPVC. The biosensors were applied to glucose measurement in natural samples of commercial orange juice

Characterization of carbon nitride thin films deposited by a combined RF and DC plasma beam

Thin carbon nitride films have been deposited on silicon(100) substrates downstream of a nitrogen plasma beam generated in a combined RF (13.56 MHz, 40–50 W) and DC (voltage ±200 V, power 1–10 W) discharge between a graphite electrode and a graphite nozzle. By combining the RF and DC sources the capability of RF field to create extended plasmas is used together with the enhanced sputtering and biasing effect of the DC source. The plasma characteristics (electron temperature, presence of molecular species) have been studied by optical emission spectroscopy. Deposition rates of 2.5–3 nm/s are obtained at the centre of the plasma beam and at a few centimetres distance from the nozzle. The films have been investigated by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, scanning and transmission electron microscopy, and microhardness measurements. The films have an overall N:C ratio of 0.28 but the distribution of different nitrogen bonds depends upon the DC bias conditions. In the spectral range 0.3–0.7 µm the refractive index increases slightly from 1.5 to 2.2. The films are amorphous, with morphology consisting of a columnar structure. The columns have a diameter of about 20 nm. A hardness of 24 GPa has been measured