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91.
K. Rózga-Wijas U. Mizerska W. Fortuniak J. Chojnowski R. Hałasa W. Werel 《Journal of Inorganic and Organometallic Polymers and Materials》2007,17(4):605-613
Three types of silica particles modified with vinyl groups were obtained: (i) xerogel formed by hydrolytic polycondensation
of the mixture of tetramethoxysilane (TMOS) and 1,1,1,7−tetramethoxy-3,5,7-trimethyl-3,5,7-trivinyltetrasiloxane, (ii) mesoporous
silica obtained from the same precursors in the presence of the cetyltrimethylammonium bromide (CTAB), and (iii) commercial
Fluka silica gel 60A with a vinyltriethoxysilane-treated surface. Vinyl groups on these silica materials were transformed
into silyl chloride by hydrosilylation with HMe2SiCl. These groups were used to graft living polysiloxane that was synthesized by anionic ring-opening polymerization of 2,4,6-tri(3-chloropropyl)-2,4,6-trimethylcyclotrisiloxane
and initiated by BuLi. Chloropropyl groups on the grafted polymer were used to quaternize N,N-dimethyl-n-octylamine. Silica particles with grafted polysiloxane having quaternary ammonium salt (QAS) groups pendant to polymer chains
were obtained. Silica material with QAS groups directly attached to the surface were generated by the action of N,N-dimethyl-n-octylamine on particles obtained by the sol–gel process involving tetraethoxysilane (TEOS) with 3-chloropropyltriethoxysilane.
The bacteriocidal properties of all these materials were tested in water suspension against five representative strains for
Gram-positive and Gram-negative bacteria. Some of the silica–polysiloxane hybrid materials have good antibacterial properties
against Gram-positive strains, but not as good as the non-tethered QAS-substituted polysiloxane in water solution. The QAS
groups that are directly bonded to the silica material surface are inactive. 相似文献
92.
The crystal structure and dielectric properties as a function of temperature for Ba-based with Bi-layered structure BaBi2Nb2O9 (BBN) ceramics were investigated. The obtained results confirmed the relaxor ferroelectric behavior of the studied ceramics,
including a strong frequency dispersion of the permittivity maximum and a visible shift of its temperature with frequency.
Analysis of the real and imaginary part of permittivity allowed us to determine the values of Burn’s temperature and of the
freezing temperature characterizing the relaxor ferroelectrics. The physical processes, responsible for the relaxor behavior
of the studied ceramics are discussed. The additional low frequency dielectric dispersion at high temperatures in the paraelectric
phase range was also observed. Correlation between this dispersion and the thermally stimulated depolarization current was
ascertained. 相似文献
93.
Andrzej Dziech Przemysław Ślusarczyk Bernd Tibken 《Journal of Intelligent and Robotic Systems》2004,39(4):447-458
In this paper an image data compression scheme based on Periodic Haar Piecewise-Linear (PHL) transform and quantization tables is proposed. Effectiveness of the compression for different classes of images is evaluated. The comparison of the compression quality using PHL and DCT transforms is given. 相似文献
94.
95.
Valery A. Isidorov Sławomir Bakier Ewa Pirożnikow Monika Zambrzycka Izabela Swiecicka 《Journal of chemical ecology》2016,42(6):475-485
Honey bees harvest resins from various plant species and use them in the hive as propolis. While there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. The main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. Samples of propolis originating from temperate zones of Europe and the supposed botanical precursors of the product were analyzed. Taxonomical markers of bud resins of two white birch species, aspen, black poplar, horse-chestnut, black alder, and Scots pine were determined through GC-MS analysis. All these trees have been reported as sources of propolis, but comparisons of the chemical composition of their bud resins with the compositions of propolis samples from seven European countries have demonstrated the presence of taxonomical markers only from black poplar, aspen, and one species of birch. This suggests selective behavior during the collection of bud resins by honeybees. To examine the causes of such selectivity, the antimicrobial properties of bud resins were determined. Horse-chestnut resins had lower antimicrobial activity than the other resins which did not differ significantly. 相似文献
96.
Sławomir Jodzis 《臭氧:科学与工程》2012,34(5):378-386
Results of studies on ozone synthesis under discharges proceeding in a metal mesh-ceramic dielectric system have been presented. The experiments were carried out in the reactor with unique reaction space geometry, in which the reacting gas flew with consequently increasing linear velocity. The high voltage electrode was made of a metal mesh, which caused intensification of the gas mixing in the reaction space. Using a simple reactor with one-side cooling of the reaction space, high ozone maximum concentrations (100 g/Nm3) and energy efficiencies (180–200 g/kWh) were obtained at 25 °C. 相似文献
97.
This paper describes assumptions, aims, methodology, content and consortium make up of a European project (SAM–EMU) founded under the Erasmus Lifelong Learning Programme. The project has developed learning materials in the field of evaluation of measurement uncertainty. It is available in the form of a multimedia web based course, which has many advantages. This format is commonly accepted as a good way to prepare an EU wide vocational training vehicle. The course is available in English. 相似文献
98.
M. Kowalska K. Fabisiak A. Wrzyszczyński A. Banaszak M. Szybowicz K. Paprocki W. Bała F. Bylicki 《Materials Science-Poland》2014,32(3):475-480
Diamond electrodes of different morphologies and qualities were manufactured by hot filament chemical deposition (HF CVD) techniques by changing the parameters of diamond growth process. The estimation of diamond quality and identification of different carbon phases was performed by Raman spectroscopy measurements. The effect of diamond quality and amorphous carbon phase content on the electrochemical response of an obtained diamond electrode in 0.5 M H2SO4 as supporting electrolyte was investigated by cyclic voltammetry with [Fe(CN)6]4?/3? as a redox probe. The kinetic parameters such as catalytic reaction rate constant k0 and electron transfer coefficient α were determined. The obtained results show that the analytical performance of undoped diamond electrodes can be implemented just by the change of diamond layers quality. 相似文献
99.
Abstract: Numerical modelling was used to follow the moisture movement and strain in a composite system – an unrestrained, single wood panel coated with a layer of gesso, in response to cyclic sinusoidal variations in relative humidity (RH). The allowable magnitude of the variations, below which physical damage of the gesso layer on the wood does not occur over a selected time of exposure, was derived as a function of cycle duration, panel thickness and moisture diffusion configuration. The dimensional response of wood substrate becomes subject to restraint by the applied layer of gesso. The panels do not respond significantly to diurnal fluctuations or shorter irrespectively of the panel thickness. The panels respond more and more significantly when the duration of the fluctuations increases until a certain critical period at which the panel fully responds to each cycle. The analysis of the data obtained indicates that moderate RH variations within the approximate range 50 ± 15% are safe. This safe range was derived using the extremes of conservative criteria of the gesso’s fatigue fracture and assumption of worst‐case wooden substrate response. The reduction of allowable amplitude of RH cycles because of decrease in the gesso’s modulus of elasticity and thickness is discussed. 相似文献
100.
K. Strzałkowski J. Zakrzewski M. Maliński 《International Journal of Thermophysics》2013,34(4):691-700
In this paper, experimental photoluminescence (PL) and piezoelectric photothermal (PPT) spectra of selected II–VI binary crystals are presented and analyzed. The quantitative analysis of the photothermal spectra was performed using a modified and extended Jackson–Amer model. The values of the bandgap energies of investigated semiconductors were computed from the PT amplitude and phase spectra. From the temperature dependence of the exciton emission so-called “excitonic energy gaps” have been determined. It follows from the theory that the exciton binding energy is the difference of these two values of energy gaps derived from PPT and PL spectroscopy. 相似文献