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81.
Kalsin AM Kowalczyk B Smoukov SK Klajn R Grzybowski BA 《Journal of the American Chemical Society》2006,128(47):15046-15047
Mixtures of oppositely charged nanoparticles of various sizes and charge ratios precipitate only at the point of electroneutrality. This phenomenon-specific to the nanoscale and reminiscent of threshold precipitation of ions-is a consequence of the formation of core-and-shell nanoparticle aggregates, in which the shells are composed of like-charged particles and are stabilized by efficient electrostatic screening. 相似文献
82.
Bigmore HR Zuideveld MA Kowalczyk RM Cowley AR Kranenburg M McInnes EJ Mountford P 《Inorganic chemistry》2006,45(16):6411-6423
One-pot reactions of V(NMe2)4 with a range of primary alkyl- and arylamines RNH2 and Me3SiCl afforded the corresponding five-coordinate vanadium(4+) imido compounds V(NR)Cl2(NHMe2)2 [R = 2,6-C6H3(i)Pr2 (1a, previously reported), 2-C6H4(t)Bu (1b), 2-C6H4CF3 (1c), (t)Bu (1d), Ad (Ad = adamantyl, 1e)]. The crystal structures of 1b (two diamorphic forms) and 1c featured N-H...Cl hydrogen-bonded chains. Reaction of 1a-e with the neutral face-capping, N3 donor ligands TACN (TACN = 1,4,7-trimethyltriazacyclononane) or TPM [TPM = tris(3,5-dimethylpyrazolyl)methane] gave the corresponding six-coordinate complexes V(NR)(TACN)Cl2 (2a-e) and V(NR)(TPM)Cl2 (3a-e). The X-ray structures of 2b, 2c, 2d, 3b, 3c, and 3e were determined. When activated with methylaluminoxane, certain of the complexes V(NR)(TPM)Cl2 (3) formed moderately active ethylene polymerization catalysts, whereas none of the compounds V(NR)(TACN)Cl2 (2) were active. 相似文献
83.
We classify all the surfaces in M2(c1)×M2(c2) for which the tangent space TpM2 makes constant angles with Tp(M2(c1)×{p2}) (or equivalently with Tp({p1}×M2(c2)) for every point p=(p1,p2) of M2. Here M2(c1) and M2(c2) are 2-dimensional space forms, not both flat. As a corollary we give a classification of all the totally geodesic surfaces in M2(c1)×M2(c2). 相似文献
84.
In this contribution, results of experimental flow investigations in a technical scale cylindrical reactor with centrally located internal reboiler are presented. The fluid motion in the kettle is induced by natural circulation. Two different geometrical configurations are considered. First, the liquid level is set below the evaporator's outlet. Thus, only the liquid phase penetrates the liquid surface. The second configuration characterizes the a direct injection of the two phase mixture into bulk liquid. In both cases the liquid leaves the evaporator radially and horizontally towards the cylindrical wall. Gathered results reveal the presence of the big, toroidal vortex in the kettle annulus. Independently on the boundary conditions, self similarity of velocity profiles in the near wall region is observed. In contrast, investigations of the momentum transfer between the jet and the bulk liquid reveal strong dependency on the geometrical configuration of the setup. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
85.
Wojciech Kicinski Jakub P.Sek Agata Kowalczyk Sylwia Turczyniak-Surdacka Anna M.Nowicka Slawomir Dyjak Boguslaw Budner Mikolaj Donten 《Journal of Energy Chemistry》2022,(1):296-308
An extensive analysis of iron-nitrogen-carbon(Fe-N-C)electrocatalysts synthesis and activity is presented concerning synthesis conditions such as initial Fe content,pyrolysis temperature and atmosphere(inert N2,reducing NH3,oxidizing Cl2 and their sequential combinations)and the influence of an external magnetic field on their performance in oxygen reduction reaction(ORR).Thermosetting porous polymers doped with FeCl3 were utilized as the Fe-N-C catalysts precursors.The pyrolysis temperature was varied within a 700-900℃range.The temperature and atmosphere of pyrolysis strongly affect the porosity and compositi on of the resultant Fe-N-C catalysts,while the in itial amount of Fe precursor shows much weaker impact.Pyrolysis under NH3 yields materials similar to those pyrolyzed under an inert atmosphere(N2).In contrast,pyrolysis under Cl2 yields carbon of peculiar character with highly disordered structure and extensive microporosity.The application of a static external magnetic field strongly enhances the ORR process(herein studied in an alkaline environment)and the enhancement correlates with the Fe content in the Fe-N-C catalysts.The Fe-N-C materials containing ferromagnetic iron phase embedded in N-doped microporous carbon constitute attractive catalysts for magnetic field-aided anion exchange membrane fuel cell technology. 相似文献
86.
In present contribution a study is presented, where fluid dynamic measurements are used to observe multiphase flow pattern in a bioreactor. It can be shown that hydrodynamic effects have a major influence on the formation, shape and size of Granular Activated Sludge (GAS) in a Sequencing Batch Reactor (SBR) under aerobic condition. In order to analyse multiphase flow pattern (water, air, granules) in the bioreactor in-situ techniques with optical measurements are applied. LASER IIIB and video lamp are used as a light source. Due to a transient spatial velocity distribution in the bioreactor our experiments are carried out in different levels of SBR. Tracer particles are employed to visualise the fluid flow pattern. Velocity field of the liquid phase in the bioreactor is determined by use of PIV method (Particle Image Velocimetry). PTV (Particle Tracking Velocimetry) is implemented to observe velocity field of individual granules (solid phase). (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
87.
Kuo-yuan Hung Renata Kowalczyk Ami Desai Margaret A. Brimble John F. Marshall Paul W. R. Harris 《Molecules (Basel, Switzerland)》2022,27(14)
A20FMDV2 is a 20-mer peptide that exhibits high selectivity and affinity for the tumour-related αvβ6 integrin that can compete with extracellular ligands for the crucial RGD binding site, playing a role as a promising αvβ6-specific inhibitor for anti-cancer therapies. Unfortunately, the clinical value of A20FMDV2 is limited by its poor half-life in blood caused by rapid renal excretion and its reported high susceptibility to serum proteases. The incorporation of poly (ethylene glycol) chains, coined PEGylation, is a well-established approach to improve the pharmacokinetic properties of drug molecules. Here, we report a systematic study on the incorporation of a varying number of ethylene glycol units (1–20) into the A20FMDV2 peptide to establish the effects of PEGylation size on the peptide stability in both rat serum and human plasma. In addition, the effect of acetyl and propionyl PEGylation handles on peptide stability is also described. Selected peptide analogues were assessed for integrin-αvβ6-targeted binding, showing good specificity and activity in vitro. Stability studies in rat serum established that all of the PEGylated peptides displayed good stability, and an A20FMDV2 peptide containing twenty ethylene glycol units (PEG20) was the most stable. Surprisingly, the stability testing in human plasma identified shorter PEGs (PEG2 and PEG5) as more resistant to degradation than longer PEGs, a trend which was also observed with affinity binding to integrin αvβ6. 相似文献
88.
89.
P. Kowalczyk A. Katern F. Engelke 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1990,17(1):47-50
Laser excitation spectroscopy is performed on K2 molecules produced in a supersonic molecular beam. 83 vibrational levels of the 21 Σ u + state are observed under conditions permitting rotational resolution. The 21 Σ u + state is partially analysed and its preliminary potential curve is compared with theoretical calculations. 相似文献
90.
A new method based on the cascade reaction between β,γ-unsaturated-α-ketophosphonates and cyclic 1,3-dicarbonyls is reported for the synthesis of highly enantiomerically enriched δ-lactones bearing a fused cyclohexenone scaffold. The target products bearing a δ-lactone moiety and one stereogenic center were obtained in good to excellent yields (83–96%) and enantioselectivities (63:32–95:5 er). The best results were obtained in the presence of a chiral Brønsted base catalyst derived from the cinchona alkaloid quinine and modified by a squaramide moiety. 相似文献