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排序方式: 共有485条查询结果,搜索用时 15 毫秒
61.
62.
Tomczyk Monika Osewski Pawel Berger Marie-Helene Diduszko Ryszard Jóźwik Iwona Adamo Giorgio Pawlak Dorota A. 《Journal of Materials Science》2021,56(19):11219-11228
Journal of Materials Science - Zinc oxide (ZnO) nanostructures exhibiting high exciton binding energy and efficient radiative recombination, even at the room temperature, are of increasing interest... 相似文献
63.
Dorota Żyżelewicz Joanna Oracz Wiesława Krysiak Grażyna Budryn Ewa Nebesny 《Drying Technology》2017,35(3):363-374
The effect of roasting parameters such as the temperature (135 and 150°C) and relative humidity of air (RH of 0.3 and 5.0%) on acrylamide, acrolein, and polycyclic aromatic hydrocarbon (PAH) levels in whole and crushed cocoa beans and chocolates derived from these beans was studied. Acrylamide was identified in all tested samples of roasted cocoa beans, irrespective of process conditions. Its contents in chocolates produced from these beans were similar. The highest acrylamide concentration was found in whole cocoa beans roasted at 135°C and RH of 5.0%. Small amounts of acrolein were present only in the roasted whole cocoa beans while neither the roasted crushed cocoa beans nor chocolates contained this aldehyde. Roasting conditions significantly affected the profile and content of PAHs in whole and crushed cocoa beans and the richest in PAHs were crushed cocoa beans roasted at 150°C and RH of 5.0%. The chocolates obtained in this study contained significantly higher concentrations of PAHs than the roasted cocoa beans used for their production. The results of the study demonstrate that optimization of roasting conditions may reduce levels of all these harmful substances in cocoa beans. 相似文献
64.
Marcin Runowski Przemysław Woźny Inocencio R. Martín Kevin Soler-Carracedo Teng Zheng Hanoch Hemmerich Fernando Rivera-López Jan Moszczyński Piotr Kulpiński Sascha Feldmann 《Advanced functional materials》2024,34(1):2307791
Nonlinear optical materials are essential in areas such as nanophotonics, optical information processing, and biomedical imaging. However, nanomaterials employed for these diverse applications to date are efficient only for one type of nonlinear optical activity. Herein, the first multimodal nonlinear optically active class of nanomaterials based on lanthanide-doped lithium niobate nanoparticles, which simultaneously exhibit unprecedentedly efficient second and third harmonic generation, as well as up-conversion photoluminescence, is reported. These dielectric nanoparticles retain their high nonlinear optical conversion efficiency both as powder and as aqueous colloidal solution. The high stability also allows for the fabrication of optically active biocompatible micron-sized fibers and polymer-based 3D-printable objects, as well as for fingerprint detection. Finally, the first 8-bit coding platform purely based on multimodal nonlinear optical activity originating from different parametric and nonparametric processes is demonstrated, showcasing the technological potential of these materials for both anti-counterfeiting and advanced optical information processing. 相似文献
65.
Iwona Kuźniarska-Biernacka Ana R. Silva Ana P. Carvalho João Pires Cristina Freire 《Catalysis Letters》2010,134(1-2):63-71
The chiral Mn(III) salen complex (C1) was immobilised onto a natural clay (BEN) and a porous clay heterostructure (PCH) functionalised with 3-aminopropyltriethoxysilane (APTES). FTIR, XPS and Mn chemical analysis confirm the C1 anchorage in both materials, but with higher efficiency in BEN_APTES clay. The catalytic activity of C1@BEN_APTES and C1@PCH_APTES, was assessed in the epoxidation of styrene (sty) and ∝-methylstyrene (∝-Mesty) using NaOCl and m-chloroperoxybenzoic acid (m-CPBA)/N-methylmorpholine-N-oxide (NMO). Both materials behave as moderate catalysts, show high epoxide selectivity but low enantiomeric excesses. In the case of sty epoxidation with m-CBPA/NMO the C1@PCH_APTES catalyst showed the highest catalytic activity, whereas in ∝-Mesty epoxidation, the C1@PCH_APTES catalyst, although leading to lower substrate conversion than the BEN analogue, presented the lowest complex leaching. In all cases, the oxidant NaOCl had some destructive effect in the hybrid catalysts, highlighting the importance of a careful choice of catalyst and oxidant system. 相似文献
66.
This research presents an analysis of the influence of graphene reinforcement on the thermal and mechanical properties of silicon carbide ceramics, at 2.5% (wt%) graphene content. The SiC composites, containing various carbon nanofillers (graphene oxide and graphene nanoparticles), were sintered by the classical two stage spark plasma sintering method. Two current modes were used, the continuous mode and the pulsed current mode. The results from photothermal radiometry and investigations of the mechanical properties showed that graphene additives significantly improve the thermal properties and toughness of material, sintered from a SiC powder. An 45% growth in the toughness was observed, which increased from 1.21 to 1.75?MPa/m1/2. The thermal diffusivity value also increased from 0.60 to 0.71?cm2/s and giving an improvement in thermal properties of 18%. The friction coefficient reached 7% giving an increase in value from 0.62 to 0.66. Microscopic investigations supported the photothermal radiometry (PTR) results. Whilst, thermal imaging revealed homogeneity of the local thermal properties of the products fabricated from the starting SiC powder. 相似文献
67.
Antoni S. Góźdź 《Polymer Bulletin》1981,4(10):577-582
Summary Synthesis of p-bromomethylstyrene (3) and p-iodome-thylstyrene (4) is reported. 3 was obtained by the bromomethylation of 2-phenylethyl bromide followed by dehydrobromination of the resultant p-(2-bromoethyl) benzyl bromide (2) with t-BuOK, as well as by cleaving p-vinyl-benzyl methanosulfonate with LiBr in the presence of 18--crown-6. 4 was obtained from p-chloromethylstyrene (1) via the Finkelstein reaction. 3 was polymerized successfully in the presence of free-radical initiators, but 4 was found to be too unstable to give a well-defined polymer. 相似文献
68.
Energy Harvesting: Electric Field Assisted Microfluidic Platform for Generation of Tailorable Porous Microbeads as Cell Carriers for Tissue Engineering (Adv. Funct. Mater. 20/2018) 下载免费PDF全文
69.
Fly ash as a sorbent for boron removal from aqueous solutions: Equilibrium and thermodynamic studies
Justyna Ulatowska Izabela Polowczyk Anna Bastrzyk Tomasz Koźlecki Wojciech Sawiński 《分离科学与技术》2020,55(12):2149-2157
ABSTRACT This study presents the application of fly ash from brown coal and biomass burning power plant as a sorbent for the removal of boron ions from an aqueous solution. The adsorption process efficiency depended on the parameters, such as adsorbent dosage, pH, temperature, agitation time and initial boron concentration. The experimental data fitted well with the Freundlich isotherm model and the maximum capacity was found to be 16.14 mg g?1. The adsorption kinetics followed the pseudo-second-order model. Also, the intra-particle diffusion model parameters were calculated. Thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°), entropy (ΔS°) revealed on exothermic nature of boron adsorption onto the fly ash. 相似文献