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排序方式: 共有220条查询结果,搜索用时 31 毫秒
31.
Alexander Ovchinnikov Dr. Matej Bobnar Dr. Yurii Prots Dr. Horst Borrmann Dr. Jörg Sichelschmidt Prof. Yuri Grin Dr. Peter Höhn 《Angewandte Chemie (International ed. in English)》2018,57(36):11579-11583
Two new calcium nitridomanganates, Ca12[Mn19N23] (P3, a=11.81341(3) Å, c=5.58975(2) Å, Z=1) and Ca133[Mn216N260] ( , a=39.477(1) Å, c=5.5974(2) Å, Z=1), were obtained by a gas–solid reaction of Ca3N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12[Mn19N23] was determined from high‐resolution X‐ray synchrotron powder diffraction data, whereas single‐crystal X‐ray diffraction was employed to establish the crystal structure of the Ca133[Mn216N260] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal–metal bond formation. 相似文献
32.
Sadik Cogal Abdulrahman K. Ali Gamze Celik Cogal Jaroslav Kulicek Matej Micusik 《高分子科学杂志,A辑:纯化学与应用化学》2018,55(4):317-323
This study presents the preparation of graphene (GR) nanocomposites with polyaniline (PANI) and polypyrrole (PPy) through the fast, versatile and environmentally friendly process of radio frequency (RF)-plasma polymerization. Morphological characterization of the nanocomposites is performed using scanning electron microscopy (SEM) and shows that the PANI and PPy conducting polymers coated the GR surface. The surface properties of the GR nanocomposites are determined using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The prepared GR nanocomposites are then used as counter electrodes in dye-sensitized solar cells (DSSCs). The conversion cell efficiencies for iodine-doped DSSC samples are found to be 0.086%, 5.41%, and 5.60% for I2-PANI, I2-PANI-GR and I2-PPy-GR, respectively, while the corresponding undoped samples reaches power conversion efficiencies of 3.82%, 1.30%, and 0.077% for PPy-GR, PANI-GR and PANI, respectively. The incident photon-to-current efficiency (IPCE) of iodine-doped composite-based DSSCs is significantly enhanced. 相似文献
33.
Matej Pavšič 《Foundations of Physics》1998,28(9):1443-1451
A relativistic, i.e., Lorentz co-variant theory without constraints is formulated. This is possible if we allow the dynamical variables to depend on an invariant parameter . Thus we obtain a dynamical theory in spacetime, called relativistic dynamics. First the case of a point particle, and then of extended objects such as membranes of arbitrary dimensions are considered. 相似文献
34.
Alberto ME Lucas MF Pavelka M Russo N 《The journal of physical chemistry. B》2008,112(35):10765-10768
We have investigated the degradation reactions, in chloride medium, of the third generation drug oxaliplatin using density functional theory. Our calculations confirm that this drug should be administered in chloride free solutions, and we have ascertained the main biodegradation products upon chloride binding, which are essential to establish the active compounds reacting with DNA. In addition, detailed knowledge of these platinum complexes is fundamental for correct elimination procedures in wastewater treatments. 相似文献
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Mercury-pyrrolidinedithiocarbamate complexes are first time used for speciation of aquatic mercury with high-performance liquid chromatographic/ion trap-mass spectrometric method utilizing atmospheric pressure chemical ionization (APCI). The separation of the four mercury species was achieved in less than 5 min with a linear gradient profile of aqueous methanol from 70 up to 100% (v/v) in 4th min, isocratic elution at 100% up to 5th min and followed by a negative gradient to 70% in 6th min. The best separation was achieved on a reverse phase Zorbax Eclipse XDB C18 column (50 mm × 2.1 mm i.d., 1.8 μm particle size). The on-column limits of detection (injection volume 1 μL) were 370 pg for methylmercury (MeHg+), 280 pg for ethylmercury (EtHg+), 250 pg for phenylmercury (PhHg+) and 90 pg for inorganic mercury (Hg2+) when the data were collected in selective ion monitoring (SIM) mode. A method of isolation and preconcentration of the mercury species using a “home-made” C18 solid phase extraction (SPE) microcolumns was developed to enhance sensitivity of the method. The preconcentration factor as much as 2500 was achieved with on-column complex formation of mercury-pyrrolidinedithiocarbamate. Methanol (100%) was chosen for elution of preconcentrated mercury species. The method was applied for the determination of mercury species in river water samples. 相似文献
37.
A fast and sensitive analytical procedure has been developed for the simultaneous separation and determination of alpha-estradiol, beta-estradiol, estriol, estrone and ethynylestradiol and their sulfate, glucuronide and acetate conjugates in river sediments. The procedure includes a microwave-assisted extraction (MAE) with aqueous methanol (25:75, v/v) at 100 degrees C in 10 min, a clean-up on Oasis WAX cartridge and a high-performance liquid chromatography-ion-trap tandem mass spectrometry (HPLC-IT-MS/MS) with electrospray ionization. The recovery for each compounds ranged from 83 to 107% and the repeatability represented as RSDs ranged from 4.9 to 9.6%. The limits of detection (LODs) were down to 1 ng g(-1). The analytical performance of the method was evaluated using determination of free and conjugated estrogens in river sediments. 相似文献
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Matejícek P Cígler P Procházka K Král V 《Langmuir : the ACS journal of surfaces and colloids》2006,22(2):575-581
Polyhedral metallacarboranes are used mainly as ion-pairing agents and recently have been recognized as potent inhibitors of HIV protease. They are characterized by exceptional hydrophobicity, rigid geometry, delocalized negative charge, ion-pairing behavior, and strong acidity of their conjugated acids. The completely novel phenomenon, association of these promising pharmaceutical tectons in aqueous solutions, is described here. The behavior of two structural types of metallacarboranes, [bis(1,2-dicarbollide)cobaltate(1-)] and bis[(3)-1,2-dicarbollylcobalt]-(3,6)-1,2-dicarbacanastide(2-)], in aqueous solution was studied by a combination of static and dynamic light scattering and microscopy methods. Spherical aggregates with radii of ca. 100 nm and fairly monodisperse nanostructures were found in aqueous solutions. The behavior of nanoaggregates is fairly complex and depends on the concentration and aging of the solutions. The particles are stabilized in the solution by counterions. The formation of larger clusters upon dilution of bis(1,2-dicarbollide)cobaltate(1-) solutions was observed. The secondary aggregation can be suppressed by addition of NaCl. Gel permeation chromatography measurements of sodium bis(1,2-dicarbollide)cobaltate(1-) show that the majority of matallacarborane molecules form nanoaggregates and only a small amount of the metallacarborane remains molecularly soluble or forms small oligomers. 相似文献