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991.
《Ceramics International》2016,42(9):10593-10598
The optimized sintering conditions for a 3.5 wt% magnesia partially stabilized zirconia (Mg-PSZ) refractory were proposed in our recent research. The influence of the sintering temperature on the development of phase composition, microstructure, densification, thermal expansion and mechanical strength was studied in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), He-pycnometer, high temperature dilatometry and three-point bending test. The samples sintered at 1670 °C had the highest bend strength, the maximum densification, the lowest thermal expansion coefficient (CTE), a homogeneous microstructure and a linear change in thermal expansion. 相似文献
992.
The paper presents a novel methodology for the rapid identification of the water diffusion coefficients of composite materials. The methodology consists in employing a numerical parametric Proper Generalized Decomposition (PGD) method allowing incorporating the diffusion coefficients among the number of degrees of freedom. Compared to classical identification schemes, often based on Finite Element Method (FEM) iterations, the proposed method allows achieving consistent CPU time gain. The method is general and can be applied when diffusion anomalies take place or when diffusion–reaction coupling must be taken into account, moreover can deal with anisotropic materials. However, for the scope of illustration, in the present case, it is applied to the simple case of “classical diffusion” (Fick’s model with constant boundary conditions) and concerns isotropic materials. 相似文献
993.
This paper presents a literature survey on the theoretical backgrounds and the past research efforts in relation to the interactions between certain thermoplastics and epoxies, and their applications in polymer blending, epoxy toughening and composite joining. The main objectives are to understand the possible mechanisms of interfacial adhesion between thermoplastic and thermoset polymers, and also to explore the feasible approaches to improve interfacial adhesion for the purposes of joining fibre reinforced polymer (FRP) composite structures by fusion bonding. Further, it is expected that the review would provide some visions to the potential applications of the thermoplastic–thermoset interfacial interactions for the quick assembly of composite structures in cost-effective manufacturing of composite structures, through the uses of the technologies, such as thermoset composite fusion bonding, welding of thermoplastic composites with thermoset composites, and thermoplastic article attachment on thermoset composites. 相似文献
994.
Dr. Yuriy V. Sheludko Dr. Jascha Volk Dr. Wolfgang Brandt Prof. Heribert Warzecha 《Chembiochem : a European journal of chemical biology》2020,21(14):1976-1980
Human drug-metabolizing cytochrome P450 monooxygenases (CYPs) have enormous substrate promiscuity; this makes them promising tools for the expansion of natural product diversity. Here, we used CYP3A4 for the targeted diversification of a plant biosynthetic route leading to monoterpenoid indole alkaloids. In silico, in vitro and in planta studies proved that CYP3A4 was able to convert the indole alkaloid vinorine into vomilenine, the former being one of the central intermediates in the ajmaline pathway in the medicinal plant Rauvolfia serpentina (L.) Benth. ex Kurz. However, to a much larger extent, the investigated conversion yielded vinorine (19R,20R)-epoxide, a new metabolite with an epoxide functional group that is rare for indole alkaloids. The described work represents a successful example of combinatorial biosynthesis towards an increase in biodiversity of natural metabolites. Moreover, characterisation of the products of the in vitro and in planta transformation of potential pharmaceuticals with human CYPs might be indicative of the route of their conversion in the human organism. 相似文献
995.
996.
Iana A. Minich Oleg I. Silyukov Liliia D. Kulish Irina A. Zvereva 《Ceramics International》2019,45(2):2704-2709
A protonated form of the n?=?4 layered bismuth containing perovskite-like titanate K2.5Bi2.5Ti4O13 belonging to Ruddlesden-Popper phases was prepared via ion exchange reaction of interlayer K+ with protons. Its composition was investigated by TG ICP and EDX analysis was found to be H2K0.5Bi2.5Ti4O13·H2O. The thermal behavior of the obtained phase was investigated by STA coupled with mass-spectrometry, the structural changes, happening with the sample during heating, were examined by XRD. It was shown that the as-prepared hydrated phase undergoes two-stage dehydration at low temperatures (up to 160?°C). The further heating leads to the gradual decomposition and crystallization of new phases, notably Bi2Ti2O7, Bi4Ti3O12 and Bi2Ti4O11. The morphology of the as-prepared sample and samples after heat treatment was examined using SEM. 相似文献
997.
Dr. Remya Rajan Dr. Dirk Schepmann Ruben Steigerwald Dr. Julian A. Schreiber Dr. Ehab El-Awaad Prof. Joachim Jose Prof. Guiscard Seebohm Prof. Bernhard Wünsch 《ChemMedChem》2021,16(20):3201-3209
Recent studies have shown the involvement of GluN2A subunit-containing NMDA receptors in various neurological and pathological disorders. In the X-ray crystal structure, TCN-201 ( 1 ) and analogous pyrazine derivatives 2 and 3 adopt a U-shape (hairpin) conformation within the binding site formed by the ligand binding domains of the GluN1 and GluN2A subunits. In order to mimic the resulting π/π-interactions of two aromatic rings in the binding site, a [2.2]paracyclophane system was designed to lock these aromatic rings in a parallel orientation. Acylation of [2.2]paracyclophane ( 5 ) with oxalyl chloride and chloroacetyl chloride and subsequent transformations led to the oxalamide 7 , triazole 10 and benzamides 12 . The GluN2A inhibitory activities of the paracyclophane derivatives were tested with two-electrode voltage clamp electrophysiology using Xenopus laevis oocytes expressing selectively functional NMDA receptors with GluN2A subunit. The o-iodobenzamide 12 b with the highest similarity to TCN-201 showed the highest GuN2A inhibitory activity of this series of compounds. At a concentration of 10 μM, 12 b reached 36 % of the inhibitory activity of TCN-201 ( 1 ). This result indicates that the [2.2]paracyclophane system is well accepted by the TCN-201 binding site. 相似文献
998.
Long Fan 《Chemical Engineering Communications》2016,203(9):1139-1144
Fiber particles have some unique behaviors due to their special shapes, which are important to those related industries. When a single fiber is in a particle cloud, its behavior will be influenced by others around it. Hence, the behavior of an isolated fiber particle will be different from that in a particle cloud, such as aggregation, orientation, and drag coefficient. However, little information is available on these phenomena, especially drag coefficient. Therefore, this article focuses on the settling process of a fiber particle in a particle cloud. Experiments were conducted to observe the settling behavior of fiber particles and to determine the drag coefficients of an isolated fiber particle in a particle cloud. The relationship between drag coefficient, orientation, and Re for different fiber particles is obtained, which is independent of volume concentration. It is further observed that the aspect ratio has little influence on the drag coefficients of fiber particles. By comparison, it is noticed that these relationships are similar to those found for an isolated single-fiber particle. Furthermore, the orientation of a fiber particle in a particle cloud fluctuates around the stable horizontal orientation in the same way as a single-fiber particle, but returns to the steady state more quickly. 相似文献
999.
Murat Özen Myrjam MertensJan Luyten Frans SnijkersHans D’Hondt Pegie Cool 《Ceramics International》2012,38(1):619-625
In this paper, the amorphous barium titanate precursor was prepared by the peroxo-hydroxide method and post-treated by various drying procedures, such as: room temperature drying, room temperature vacuum drying and vacuum drying at 50 °C. The objective in the latter two treatments was to increase the Ti-O-Ba bonds of the precursor. The post-treated precursors were compared with the untreated (i.e., ‘wet’) precursor. Also, a barium titanate precursor was prepared by an alkoxide route. Afterwards, the precursors were hydrothermally treated at 200 °C in a 10 M NaOH solution. Vacuum drying of the precursor seemingly promoted the formation of Ti-O-Ti bonds in the hydrothermal end-product. The low Ba:Ti ratio (0.66) of the alkoxide-route prepared precursor lead to a multi-phase hydrothermal product with BaTiO3 as the main phase. In contrast, phase pure BaTiO3, i.e. without BaCO3 contamination, was obtained for the precursor which was dried at room temperature. Cube-shaped and highly crystalline BaTiO3 particles were observed by electron microscopy for the hydrothermally treated peroxo-hydroxide-route prepared precursor. 相似文献
1000.
Konrad J?drzejewski 《Measurement》2012,45(2):170-174
The paper presents a new method of elimination of influence of drift-like errors in so called intelligent cyclic A/D converters, in particular, errors caused by drifts (droops) of voltage at the output of sample-and-hold blocks. The method is based on application of the extended multi-dimensional algorithm, which estimates simultaneously values of the input sample and drift rate. Implementation of the extended algorithm in the intelligent cyclic A/D converters requires only insignificant changes in the digital part of the converter and does not increase their production costs. The motivations to these investigations resulted from practical realizations of the intelligent cyclic A/D converter in CMOS technology and difficulties in design of a precise sample-and-hold circuit. The results of selected simulation experiments related to analysis of influence of a droop rate on the final performance of the intelligent cyclic A/D converters employing the standard (one-dimensional) and extended algorithms are discussed and compared in the paper. The results of experiments show that application of the proposed solution enables efficient functioning of the converters even in the presence of relatively large drifts. 相似文献