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61.
The heat capacity at constant pressure of CuGe2P3 is measured in the temperature range from 180 to 550 K. Standard enthalpies and entropies relative to 298.15 K are calculated from the heat capacity data. The Debye temperature in the high-temperature limit is estimated to be about 710 K. 相似文献
62.
Stanislaw Penczek Tadeusz Biela Pawel Klosinski Grzegorz Lapienis 《Macromolecular Symposia》1986,6(1):123-153
The mechanism of polymerization is discussed, in which cyclic esters of phosphoric acid, and related compounds are converted into linear macromolecules, modelling nucleic and teichoic acid backbones. Structures like deoxyribose polyphosphate and glycerol polyphosphate were prepared from the corresponding cyclic compounds. These polymerizations involve heterolytic breaking of the P-O bond in the cyclic monomer and proceed by ionic mechanism. Both 5- and 6-membered monomers have been polymerized. The thermodynamic parameters of the ring-chain interconversion were determined; the 5-membered rings polymerization is driven by the exothermicity of the ring-opening, whereas polymerization of several 6-membered rings is endothermic and allowed because of the positive change of entropy. Anionic polymerization, and particularly the pseudo(coordinate)anionic polymerization provides, in contrast to the cationic process, high-molecular-weight polymers with more uniform structure. Anionic polymerization proceeds mostly (at the applied conditions) on the macroion – -pairs. The elementary reactions consist of the nucleophilic attack of the paired macroanions on the phosphorus atom in the cyclic monomer molecule. Rate constants of the elementary reactions for the model monomers will be presented. Stereochemistry of the propagation steps is shown to be governed by the statistical ring-opening, leading to the three kinds of polymer units (head-to-tail and two symmetrical units). Apart from the ring-opening, the polyaddition of diepoxides to phosphorous and phosphoric acids is described. Finally, a few examples of preparation of models of biopolymers are given, namely poly(deoxyribose phosphate) and poly(glycerol phosphate). 相似文献
63.
Alicja Nejman Anna Baranowska-Korczyc Katarzyna Ranoszek-Soliwoda Izabela Jasiska Grzegorz Celichowski Magorzata Cielak 《Molecules (Basel, Switzerland)》2022,27(6)
New functionalization methods of meta- and para-aramid fabrics with silver nanowires (AgNWs) and two silanes (3-aminopropyltriethoxysilane (APTES)) and diethoxydimethylsilane (DEDMS) were developed: a one-step method (mixture) with AgNWs dispersed in the silane mixture and a two-step method (layer-by-layer) in which the silanes mixture was applied to the previously deposited AgNWs layer. The fabrics were pre-treated in a low-pressure air radio frequency (RF) plasma and subsequently coated with polydopamine. The modified fabrics acquired hydrophobic properties (contact angle ΘW of 112–125°). The surface free energy for both modified fabrics was approximately 29 mJ/m2, while for reference, meta- and para-aramid fabrics have a free energy of 53 mJ/m2 and 40 mJ/m2, respectively. The electrical surface resistance (Rs) was on the order of 102 Ω and 104 Ω for the two-step and one-step method, respectively. The electrical volume resistance (Rv) for both modified fabrics was on the order of 102 Ω. After UV irradiation, the Rs did not change for the two-step method, and for the one-step method, it increased to the order of 1010 Ω. The specific strength values were higher by 71% and 63% for the meta-aramid fabric and by 102% and 110% for the para-aramid fabric for the two-step and one-step method, respectively, compared to the unmodified fabrics after UV radiation. 相似文献
64.
Florin Radu Alexei Nefedov Johannes GrabisGregor Nowak Andre BergmannHartmut Zabel 《Journal of magnetism and magnetic materials》2006
We have used soft X-ray resonant magnetic scattering (XRMS) to search for the presence of an effective ferromagnetic moment belonging to the antiferromagnetic (AF) layer which is in close contact with a ferromagnetic (F) layer. Taking advantage of the element specificity of the XRMS technique, we have measured hysteresis loops of both Fe and CoO layers of a CoO(40 Å)/Fe (150 Å) exchange bias bilayer. From these measurements we have concluded that the proximity of the F layer induces a magnetic moment in the AF layer. The F moment of the AF layer has two components: one is frozen and does not follow the applied magnetic field and the other one follows in phase the ferromagnetic magnetization of the F layer. The temperature dependence of the F components belonging to the AF layer is shown and discussed. 相似文献
65.
Werner-Georg Nowak 《Monatshefte für Mathematik》1979,87(4):297-307
In this paper we consider lattice points in domains bounded by algebraic curves of the formx
n+yn=Rn fulfilling the additional condition
where and are fixed positive real numbers. The number of these lattice points is estimated for largeR and it appears that for rational or badly approximable and the error term in the final result can be made smaller (at least forn3) than it is best possible when counting the lattice points without the additional condition indicated above. 相似文献
66.
The hysteresis in Ni/Pb multilayers with layer thickness of 1.7, 5.5, 9.4 and 24.8 nm have been examined at low and room temperatures. The Stoner-Wohlfarth model, modified by the introduction of a constant internal field, well describes the shape of experimental hysteresis loops. The two components of internal field and anisotropy constant are fit to an individual loop. The transversal component of the internal field is related to a dispersion of local magnetization directions and determines a deviation of the rotation process from the Stoner-Wohlfarth model. At room temperature, the transversal component of the internal field for Ni/Pb multilayers is about 1000 Oe and is much greater than the effective anisotropy field and, as a result, the directions of magnetization rotate smoothly under the influence of resultant field. At low temperature, the longitudal component of the internal field is of the order of 1000 Oe and determines the incoherent rotations. 相似文献
67.
68.
Litak Grzegorz Margielewicz Jerzy Gąska Damian Yurchenko Daniil Dąbek Krzysztof 《Nonlinear dynamics》2020,102(4):2125-2142
Nonlinear Dynamics - This paper examines the oscillations of a spherical pendulum with horizontal Lissajous excitation. The pendulum has two degrees of freedom: a rotational angle defined in the... 相似文献
69.
Bochenek Dariusz Niemiec Przemysław Szafraniak-Wiza Izabela Dercz Grzegorz 《Journal of Thermal Analysis and Calorimetry》2020,141(1):5-14
Journal of Thermal Analysis and Calorimetry - Numerical predictions of flow boiling in a square tube rotating in vertical direction at a uniform rotating speed are presented. There-dimensional... 相似文献
70.
Ryszard Krzyminiewski Bernadeta Dobosz Grzegorz Schroeder Joanna Kurczewska 《Physics letters. A》2018,382(44):3192-3196
The paper shows the application of a new method – Magnetic Nanoparticles Focusing 3D, MNF-3D – for focusing of magnetic nanoparticles at any point in a three-dimensional space between the rotating magnet system. The results of focusing process of nanoparticles in water, human blood, human serum and polyurethane sponge are presented. Additionally, blood flow was also considered. The effectiveness of nanoparticle focusing was monitored optically and quantitatively by electron spin resonance method. The method enabled focusing of magnetic nanoparticles within a few minutes in different environments. A good efficiency of focusing process was observed for all the samples. 相似文献