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931.
Bogdan M. Benin Kyle M. McCall Michael Wrle Viktoriia Morad Marcel Aebli Sergii Yakunin Yevhen Shynkarenko Maksym V. Kovalenko 《Angewandte Chemie (International ed. in English)》2020,59(34):14490-14497
Low‐dimensional ns2‐metal halide compounds have received immense attention for applications in solid‐state lighting, optical thermometry and thermography, and scintillation. However, these are based primarily on the combination of organic cations with toxic Pb2+ or unstable Sn2+, and a stable inorganic luminescent material has yet to be found. Here, the zero‐dimensional Rb7Sb3Cl16 phase, comprised of isolated [SbCl6]3? octahedra and edge‐sharing [Sb2Cl10]4? dimers, shows room‐temperature photoluminescence (RT PL) centered at 560 nm with a quantum yield of 3.8±0.2 % at 296 K (99.4 % at 77 K). The temperature‐dependent PL lifetime rivals that of previous low‐dimensional materials with a specific temperature sensitivity above 0.06 K?1 at RT, making it an excellent thermometric material. Utilizing both DFT and chemical substitution with Bi3+ in the Rb7Bi3?3xSb3xCl16 (x≤1) family, we present the edge‐shared [Sb2Cl10]4? dimer as a design principle for Sb‐based luminescent materials. 相似文献
932.
Bogdan Czajka Michał Zieliński Maria Wojciechowska Iwona Tomska-Foralewska 《Journal of Solid State Electrochemistry》2014,18(8):2351-2358
This paper describes the synthesis and texture of the MgF2-MgO system used as an immobilizing agent of the electrolyte (KCl-LiCl-RbCl) for high-temperature cells. Preparations containing 20 and 40 mol% MgF2 were characterized by a mesoporous structure and large specific surface areas. It was demonstrated that pellets containing 40–50 mas.% of MgF2-MgO immobilizing agent were good electrolyte immobilizers. The ionic conductivity of pellets investigated in this work ranged from 0.02 to 0.04 S/cm, and it was about 20 times lower than the value set for the pure electrolyte. The difference is due to the tortuosity of the pellet. This mixture remains dimensionally stable at 400 °C and under 60 kPa and reveals good ionic conductivity during tests in a model cell with a 1.32-Ω resistor. During the discharge of the cell, it was observed that the voltage was not less than 1.5 V and current more than 1 A for approximately 100 s. No leakage of the electrolyte was observed. 相似文献
933.
934.
A. L. Tarasov O. A. Kirichenko N. N. Tolkachev I. V. Mishin A. N. Kalenchuk V. I. Bogdan L. M. Kustov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(7):1122-1126
The activity of Pt/C and Pd/C catalysts in the dehydrogenation of perhydroterphenyl was studied at conversions lower than
30% depending on the dispersion of platinum and palladium metals, which was estimated by two independent methods (adsorption
of CO and X-ray diffraction). 相似文献
935.
Dr. Ion Bunia Dr. Vlad Socoliuc Dr. Ladislau Vekas Dr. Florica Doroftei Dr. Cristian Varganici Dr. Adina Coroaba Prof. Bogdan C. Simionescu Dr. Marcela Mihai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18036-18044
The preparation of superparamagnetic composites obtained by CaCO3 mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water‐based magnetic fluid and insoluble templates as gel‐like cross‐linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross‐linked copolymer—a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)—were used, as well as different addition orders of magnetite and CaCO3 crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X‐ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO3, and magnetite in the composite particles were shown to be present by energy dispersive X‐ray (EDX), XPS, and TEM. The sorption capacity for CuII ions was tested, as compared to samples prepared without magnetite. 相似文献
936.
Understanding Amyloid‐β Oligomerization at the Molecular Level: The Role of the Fibril Surface
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Dr. Bogdan Barz Dr. Birgit Strodel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(26):8768-8772
The aggregation of the amyloid β‐peptide into fibrils is a complex process that involves mechanisms such as primary and secondary nucleation, fibril elongation and fibril fragmentation. Some of these processes generate neurotoxic Aβ oligomers, which are involved in the development of Alzheimer's disease. Recent experimental studies have emphasized the role of the fibril as a catalytic surface for the production of highly toxic oligomers during secondary nucleation. By using molecular dynamics simulations, we show that it is the hydrophobic fibril region that causes the structural changes required for catalyzing the formation of β‐sheet‐rich Aβ1‐42 oligomers on the fibril surface. These results reveal, for the first time, the molecular basis of the secondary nucleation pathway. 相似文献
937.
Synthesis of Monofunctionalized Silsesquioxanes (RSiMe2O)(iBu)7Si8O12 via Alkene Hydrosilylation
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The research presented in this work comprehensively describes hydrosilylation of a wide spectrum of alkenes which contain one or more reactive groups with (HSiMe2O)(iBu)7Si8O12, in the presence of different types of catalysts. Special attention is paid to the influence of alkene, catalyst, and reaction conditions on process effectiveness and selectivity by the precise monitoring of the experiments with in situ FTIR and NMR spectroscopies. More than twenty silsesquioxanes bearing reactive groups (OH, Br, NR2, CO, COOR, NCO, epoxy, SiR3) commonly used in organic and polymer chemistry, were obtained, isolated and characterized by 1H, 13C, 29Si NMR and MALDI TOF. Importantly, in the presented syntheses, commercially available reagents and catalysts were used, meaning that the presented methods could be easily repeated, rapidly scaled up, and widely applied. 相似文献
938.
Dragos Astanei François Faubert Stéphane Pellerin Bogdan Hnatiuc Maxime Wartel 《Plasma Chemistry and Plasma Processing》2018,38(5):1115-1132
The ignition sparks provided by the conventional spark plug do not always ensure a fast and complete combustion of the hydrocarbon-air mixture. For this reason, we offer a new type of plug with a double spark using two simultaneous discharges generated by a pulsed high voltage-power supply. This work presents the comparison of two spark plugs, a classical one and a double spark plug, by analyzing the unburned hydrocarbon gases from the exhaust pipe of the engine. For a first gasoline engine, we measure the oxygen concentration in the exhaust gases with a lambda probe and the unburned hydrocarbon by the use of GC–MS coupled with SPME extraction technique. We can observe a clear decrease of total unburned hydrocarbon (THC). For a second motor test bench, powered with propane, we complete measures in function of air/fuel ratio of the THC, NOx, CO2 and CO. These results confirm that we obtained a better combustion especially for leaner mixtures. 相似文献
939.
Advection–dispersive phenomena inside two geometries of porous media, corresponding to a structured and unstructured network of minichannels, are studied from a combination of analytical, numerical, and electrodiffusion techniques. The instantaneous limiting diffusion current, connected to the concentration of electroactive species flowing in the porous matrix, is recorded and measured during flow experimentation. Transport phenomena investigation consists of the step injection of a tracer of higher concentration than the bulk flow in order to characterize the mixing of electrolyte species inside two arrangements of network, so called \(\times \) _network and T_network. The experimental results are supported by 2D-numerical simulations performed in the \(\times \) _network. A pore model is proposed in order to predict the pore velocity, which is used within the resolution of the diffusion–convection balance. The numerical simulations, based on a second-order finite difference scheme, give rise to a good agreement in terms of mixing index and the methodology employed for the numerical injection concentration appears suitable. The numerical experiments are quite-well representative in laminar regime below the critical Reynolds number ( \(Re_{\mathrm{crit}}\approx \,200\) ). Above \(Re_{\mathrm{crit}}\) , the inertial effects are not negligible and the momentum transfer needs to be taken into account. This latter phenomenon is analyzed at the pore-scale in term of local skin friction measured at the channels crossing, then compared and discussed from analytical solutions. 相似文献
940.
Dagmara I. Strumińska-Parulska Bogdan Skwarzec Magdalena Pawlukowska 《Isotopes in environmental and health studies》2013,49(4):526-542
In this study, different chemical plutonium fractions (dissolved in water, connected to carbonates, connected to oxides, complexed with organic matter, mineral acids soluble and the rest) in sediments from the Vistula River estuary, the Gdańsk Basin and the Bornholm Deep were determined. The distribution of 239+240Pu in analysed sediments samples was not uniform but dependent on its chemical form, depth and the sediment geomorphology. The highest amount of plutonium exists in middle parts of sediments and comes from the global atmospheric fallout from nuclear tests in 1958–1961. According to all analysed fractions, the biggest amount of 239+240Pu was in the mobile form, connected to carbonate fractions from the Vistula River estuary, the Gulf of Gdańsk and the Bornholm Deep sediments. 相似文献