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101.
Iwona Kwiecień Grażyna Adamus Marek Kowalczuk 《Rapid communications in mass spectrometry : RCM》2012,26(23):2673-2682
102.
Piotr Kulpinski Marek Namyslak Tomasz Grzyb Stefan Lis 《Cellulose (London, England)》2012,19(4):1271-1278
UV- active cellulose fibers were obtained by dry-wet method spinning an 8?% by weight α-cellulose solution in N-methylomorpholine-N-oxide (NMMO) modified by europium-doped gadolinium oxyfluoride Gd4O3F6:Eu3+ containing 5?mol (%) of the dopant. Photoluminescent nanoparticles were introduced in the in powder form into a polymer matrix during the process of cellulose dissolution in NMMO. The dependencies of emission intensity on excitation energy and the concentration of Gd4O3F6:Eu3+ nanoparticles in the final cellulosic products were examined by photoluminescence spectroscopy (excitation and emission). The fiber structure was studied by X-ray powder diffraction analysis. The size and dispersity of the nanoparticles in the polymer matrix were evaluated using scanning electron microscopy and X-ray microanalysis. The influence of different concentration particles (in the range from 0.5 to 5?% by weight) on the mechanical properties of the fibers, such as tenacity and elongation at break, were determined. 相似文献
103.
The influence of solvents and catalysts on the formation of soluble and insoluble polymer during cationic polymerization of 2,5-dimethyl-l,5-hexadiene was studied. In nonpolar medium (n-heptane or without solvent) the amount of the insoluble part is dependent on the catalyst used and increases as follows: BF3 ? AlBr3 < TiCl4. Especially soluble polymers are obtained in a solution of methylene chloride or in a mixture of methylene chloride-nitrobenzene. The temperature range studied, -30° to -78°, did not show any important influence on the polymer composition. It was found that the bulky anion of the initiator and the polarity of the medium considerably influenced cyclization during intra-intermolecular propagation of the polymer chain. 相似文献
104.
The polymerization of isobutylene with VCl4 in n-heptane or in the bulk does not proceed in the dark at temperatures lower than -20°C, yet it may be induced by the addition of styrene, α-methylstyrene, p-divinylbenzene, 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene. In these cases the polymerizations proceed with variously long induction periods depending on the type of comonomer used. The shortest induction period was observed after the addition of p-divinylbenzene and 2, 3-dimethyl-1, 3-butadiene. In a nonpolar medium the copolymerization of isobutylene with isoprene or butadiene in the dark gives rise to copolymers insoluble in heptane, benzene, and CCl4, while co-polymers formed with the effect of light are soluble. Unlike polymerizations carried out in a nonpolar solution, the polymerization of isobutylene with VCl4 in methyl chloride proceeds spontaneously in the absence of protonic coinitiators. Also, soluble copolymers of isobutylene with isoprene or butadiene arise in the copolymerization in methylchloride solution irrespective of the procedure used when the copolymerization is carried out (in the dark or with the effect of light). Polymerizations and copolymerizations carried out both in nonpolar and in polar solutions are inhibited by the presence of oxygen. 相似文献
105.
Heteroaromatic N-oxides bearing various functionalities are readily and selectively converted under mild conditions into the corresponding bases using TiCl4/SnCl2. 相似文献
106.
Fuzzy identification of cutting acoustic emission with extended subtractive cluster analysis 总被引:1,自引:0,他引:1
This paper presents fuzzy acoustic emission identification in high precision hard turning process based on extended subtractive
cluster analysis combined with the least-square estimation method. The fuzzy identification method provides a simple way to
arrive at a definite conclusion based upon the information obtained with the difficulty in understanding the exact physics
of the machining process. The experimental results prove that the proposed method is efficient and feasible. 相似文献
107.
108.
Matúš Durec Francesco Zaccaria Dr. Célia Fonseca Guerra Prof. Dr. Radek Marek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10912-10922
Repetitive guanine‐rich nucleic acid sequences play a crucial role in maintaining genome stability and the cell life cycle and represent potential targets for regulatory drugs. Recently, it has been demonstrated that guanine‐based ligands with a porphyrin core can be used as markers of G‐quadruplex assemblies in cell tissues. Herein, model systems of guanine‐based ligands are explored by DFT methods. The energies of formation of modified guanine tetrads and those of modified tetrads stacked on the top of natural guanine tetrads have been calculated. The interaction energy has been decomposed into contributions from hydrogen bonding, stacking, and ion coordination and a twist–rise potential energy scan has been performed to find the individual local minima. Energy decomposition analysis reveals the impact of various substituents (F, Cl, Br, I, Me, NMe2) on individual energy terms. In addition, cooperative reinforcement in forming the modified and stacked tetrads, as well as the frontier orbitals participating in the hydrogen‐bonding framework involving the HOMO–LUMO gap between the occupied σHOMO on the proton‐accepting C=O and =N? groups and unoccupied σLUMO on the N?H groups, has been studied. The investigated systems are demonstrated to have a potential in ligand development, mainly due to stacking enhancement compared with natural guanine, which is used as a reference. 相似文献
109.
Rafa? Janus Piotr Natkański Anna Wach Marek Drozdek Zofia Piwowarska Pegie Cool Piotr Ku?trowski 《Journal of Thermal Analysis and Calorimetry》2012,110(1):119-125
Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723?K) of the deposited PAN was analyzed. It was found that at about 523?K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623?K, were responsible for the high sorption capacity in the methyl?Cethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface. 相似文献
110.
Góźdź Marek Góźdź Andrzej Gusev Alexander A. Vinitsky Sergue I. 《Physics of Atomic Nuclei》2018,81(6):853-857
Physics of Atomic Nuclei - We discuss the problem of the time variable in the nearly standard formulation of the quantum mechanics. In order to be able to describe the outcome of some of the... 相似文献