221 research outputs found

    Customization of the Telecommunication Market Based on the Application of the Concept of Service Products

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    The analysis of the structure and dynamics of the main indicators of the Russian telecommunication services market shows the achievement of saturation state of this market and the exhaustion of extensive sources of growth. Given the presence of a complex of negative socioeconomic factors, the source of maintaining the market positions of telecommunication companies is the customization of the services offered. For this purpose, the concept of the service products can be applied, involving the inclusion of the additional, accompanying and derivative services into the customer service package. The prerequisites for the application of the concept of the service product in the telecommunication field are the availability of the multiattribute properties and interdependence of elements in the product of that field. On the telecommunication market we can consider three types of service products. Customization of the Russian market of telecommunication services is carried out taking into account its strong state protectionism, which is conditioned by the strategic importance and the high social significance of the telecommunication industry. Saturation of the market in the conditions of oligopoly and sophistication of consumers stimulate the telecommunication companies to include in their market offer the service products of all three types

    Synthesis and optimisation of IrO2 electrocatalysts by Adams fusion method for solid polymer electrolyte electrolysers

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    IrO2 as an anodic electrocatalyst for the oxygen evolution reaction (OER) in solid polymer electrolyte (SPE) electrolysers was synthesised by adapting the Adams fusion method. Optimisation of the IrO2 electrocatalyst was achieved by varying the synthesis duration (0.5 – 4 hours) and temperature (250 - 500°C). The physical properties of the electrocatalysts were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction (XRD). Electrochemical characterisation of the electrocatalysts toward the OER was evaluated by chronoamperometry (CA). CA analysis revealed the best electrocatalytic activity towards the OER for IrO2 synthesised for 2 hours at 350oC which displayed a better electrocatalytic activity than the commercial IrO2 electrocatalyst used in this study. XRD and TEM analyses revealed an increase in crystallinity and average particle size with increasing synthesis duration and temperature which accounted for the decreasing electrocatalytic activity. At 250°C the formation of an active IrO2 electrocatalyst was not favoured

    Fiber Optic Devices for Endobiliary Photodynamic Therapy

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    The aim of the study is to optimize the irradiation procedure during endobiliary photodynamic therapy for patients with cholangiocarcinoma. The studies were performed using fiber-optic light delivery tools in various configurations and using different irradiation power levels. Control of photosensitizer accumulation at the site of therapy was also applied. It is shown that the use of fiber-optic light delivery tools with cylindrical diffusers provides more effective and less painful photodynamic therapy. It is shown that after the injection of the photosensitizer, there is an optimal time for the therapy, when the maximum difference in the accumulation of the photosensitizer in the tumor is observed in comparison with the intact tissue.     Keywords: endobiliary photodynamic therapy, fluorescent diagnostics, fiber-optic light delivery tools, cholangiocarcinom

    Preparation and Characterization of Sulfonated Poly (ether ether ketone)/Phosphated Zirconia Nanoparticles Composite Proton-conducting Membranes

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    Proton-conducting membranes of organic–inorganic (sulfonated poly (ether ether ketone)/phosphated zirconia nanoparticles) composite were prepared by incorporating various ratios of phosphated zirconia nanoparticles (ZP) in sulfonated poly (ether ether ketone) (SPEEK). SPEEK/ZP showed an improvement of properties compared with those of the parent SPEEK membrane. Key amongst these is increased proton conductivity to 0.02Scm–1, reduced water uptake to 22 % and reduced methanol permeability to 1.13 × 10–7 cm2 s–1. The methanol permeability was decreased by 28 % compared with SPEEK membrane. It was decreased by one order of magnitude compared with commercial Nafion® 117 (1.39 × 10–6 cm2 s–1).KEYWORDS: Composite membrane, phosphated zirconia, proton conductivity, SPEEK; methanol permeability, direct methanol fuel cell

    Performance and Structure of LiNi0.5Mn1.5O4 Prepared from Various Ni Precursors for Lithium Ion Batteries

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    LiNi0.5Mn1.5O4 compounds were prepared through a solid-state reaction using various Ni precursors. The effect of the precursors on the electrochemical performance of LiNi0.5Mn1.5O4 was investigated. LiNi0.5Mn1.5O4 made from Ni(NO3)2•6H2O shows the best charge-discharge performance. The reversible capacity of LiNi0.5Mn1.5O4 is about 145mAh g–1 and remained at 143mAh g–1 after 10 cycles at 3.0 to 5.0 V. The XRD results showed that the precursors and dispersion method had significant effects on their structures. Pure spinel phase can be obtained with a high energy ball-milling method and Ni(NO3)2•6H2O as precursor. A trace amount of the NiO phase was detected in LiNi0.5Mn1.5O4 with the manual grinding method when Ni(CH3COO)2•6H2O, NiO and Ni2O3 were used as precursors.Keywords: LiNi0.5Mn1.5O

    Palygorskite Hybridized Carbon Nanocomposite as a High-Performance Electrocatalyst Support for Formic Acid Oxidation

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    A nanocomposite, in which acid-treated palygorskite was hybridized with carbon, was prepared and designed as an efficient support for electrocatatlysts. Pd nanoparticles were deposited on the hybrid support as an electrocatalyst for formic acid oxidation. The hybrid supports and electrocatalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).TEM and XRD results showed that acid treatment had an effective impact on the morphology of palygorskite, but did not destroy its architecture. XPS results indicated that the introduction of palygorskite resulted in a negative shift of binding energy of Pd deposited on it. The electrochemical results showed that the addition of palygorskite into the carbon facilitated the formation of OHads or Oads on the surface of Pd/C-PLS, and further improved the formic acid electrooxidation activity. Therefore, considerable improvements in electrocatalytic activity toward formic acid oxidation was achieved by using this hybrid support when compared with conventional carbon support, suggesting that the introduction of SiO2-based porous palygoriskite was an excellent and cost-efficient way to improve the electrocatalytic performance of carbon support.KEYWORDS Palygorskite, electrocatalyst, composite support, formic acid electrooxidation

    Two-stage ZnS Shell Coating on the CuInS2 Quantum Dots for Their Effective Solubilization

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    High-precision diagnostics is one of the necessary conditions for effective treatment of diseases. Bioimaging is one of the most promising modern methods of tumor diagnosis. High-quality luminophores are necessary for effective bio-imaging. CuInS2(CIS) quantum dots (QDs) are very promising luminophores for these applications due to their low toxicity and long-term stability of their properties. Two batches of CIS QDs with different positions of the luminescence maximum have been obtained. The position of the luminescence maximum can be controlled by changing the Cu to In ratio; a decrease in this ratio cause a blue shift of the luminescence. The standard procedure of CIS synthesis yields QDs covered with thiols, which form strong bonds with the surface and prevent the ligand exchange; hence, it is very hard to adapt CIS QDs for biological tasks using the standard hydrophobic to hydrophilic ligand exchange procedure. We have developed a two-stage shell coating procedure yielding CIS QDs covered with amines, which is suitable for ligand exchange; hence,the resultant QDs can be adapted for modern biological and medical applications. Keywords: Quantum dots, CuInS2, solubilization

    Highly Active, Carbon-supported, PdSn Nano-core, Partially Covered with Pt, as Catalysts for Methanol Oxidation

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    Carbon-supported, Pt partially covered, PdSn alloy nanoparticles (Pt-PdSn/C) were synthesized via a metathetical reaction of PdSn alloy nanoparticles, and a platinum precursor. The electrochemical activity was evaluated by methanol oxidation. The Pt-PdSn/C catalysts were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CV). TEM showed that Pt grows layer-by-layer on the surface of PdSn cores and the thickness of the Pt shell is 0.2 nm, about 1–2 monolayers thick. Cyclic voltammetry results showed that PdSn/C nanoparticles, partially covered by Pt, have a better electrocatalystic performance than conventional PtRu/C and PtPdSn/C catalysts. Electrochemical active surface areas of the Pt-PdSn/C was 2.30 times larger than that of PtRu/C and 1.8 times higher than that of PtPdSn/C catalysts. The results showed that a metathetical reaction is an efficient way of preparing, low Pt loading, highly active electrocatalyst, for methanol oxidation, thus offering great potential for producing Pt-based electrocatalyst for direct methanol fuel cells on a large scale.Keywords: Electrocatalyst, fuel cell, methanol oxidation, Pt-decorate
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