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21.
Sami-Pekka Hirvonen Mikko Mänttäri Valter Wigren Mikko Salomäki Carita Kvarnström Heikki Tenhu 《Colloid and polymer science》2011,289(9):1065-1072
Poly(benzimidazobenzophenanthroline) (BBL) was prepared according to literature method and modified with poly(ethylene oxide)
in a one pot synthesis. After precipitation in aqueous sodium carbonate solution and subsequent purification, aqueous dispersions
were prepared by ultrasonication. Particle sizes in the dispersions ranged from few tens of nanometers to several micrometers
and most of the particles had sizes of 50–250 nm. Further studies indicated that the colloidal stability is a combined result
of steric stabilization caused by excluded volume interactions of PEO chains on particle surface and electrostatic stabilization
by the dissociated carboxylic acid groups on the particle surface. The product could be processed into uniform films 20–30 nm
in thickness by spin coating onto gold-plated silicon substrates having aminethiol monolayer as the top most layer. 相似文献
22.
The following results are obtained.
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- An open neighbornet U of X has a closed discrete kernel if X has an almost thick cover by countably U-close sets.
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- Every hereditarily thickly covered space is aD and linearly D.
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- Every t-metrizable space is a D-space.
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- X is a D-space if X has a cover {Xα:α<λ} by D-subspaces such that, for each β<λ, the set ?{Xα:α<β} is closed.
23.
Pekka NikkilÄ Tom Johnsson Heikki Rosenqvist Leena Toivonen 《Applied biochemistry and biotechnology》1996,59(3):245-257
Growth and fatty acid composition of two lactobacilli,Lactobacillus büchneri andLactobacillus fermentum, were studied at different pHs of the media in a small-scale fermenter with particular interest in lactobacillic acid production
of the cultures. Generally, the total fatty acid content of the bacterial cells increased with increasing culture age. The
production of lactobacillic acid was affected in the two lactobacilli by both culture age and pH of the media, but in a very
different manner. In L.büchneri cultures, the relative proportion of lactobacillic acid was highest when the pH was lowest (pH 4.5), whereas inL. fermentum cultures, the proportion of lactobacillic acid was highest at pH 7.0. The pH of the medium affected not only the relative
proportion of lactobacillic acid, but also biomass production and total fatty acid accumulation of the cultures. Thus, by
controlling the pH of the cultures, the volumetric yield of lactobacillic acid could be improved considerably compared to
cultures without pH control. 相似文献
24.
Componentwise adaptation for high dimensional MCMC 总被引:1,自引:0,他引:1
Summary We introduce a new adaptive MCMC algorithm, based on the traditional single component Metropolis-Hastings algorithm and on
our earlier adaptive Metropolis algorithm (AM). In the new algorithm the adaption is performed component by component. The
chain is no more Markovian, but it remains ergodic. The algorithm is demonstrated to work well in varying test cases up to
1000 dimensions. 相似文献
25.
26.
Heikki Pietila Arto Sivola Howard Sheffer 《Journal of polymer science. Part A, Polymer chemistry》1970,8(3):727-737
Molecular weight distributions determined by gel permeation chromatography demonstrate that α-methylstyrene copolymerizes with both β-pinene and styrene, forming both bi- and terpolymers. The composition of precipitated polymer versus crude polymer, as determined by nuclear magnetic resonance, suggests that β-pinene and styrene also copolymerize. Extraction of the latter bipolymer of β-pinene and styrene with acetone gives only a small amount of insoluble β-pinene homopolymer, confirming that β-pinene and styrene copolymerize in m-xylene. GPC analysis shows that each copolymer contains some homopolymer. A comparison of M n with molecular weight calculated from NMR analysis, assuming chain transfer to solvent, indicates that chain transfer is the predominant method of forming dead polymer. The carbonium ions of the growing chain tend to transfer to solvent with increasing ease in the order β-pinene, styrene, and α-methylstyrene. 相似文献
27.
The electronic structures and the spin density distributions of the paramagnetic gallium 1,4-diaza(1,3)butadiene (DAB) model systems [((t)Bu-DAB)Ga(I)[Pn(SiH3)2]]* and the related dipnictogen species [((t)Bu-DAB)Ga[Pn(SiH3)2]2]* (Pn = N, P, As) were studied using density functional theory. The calculations demonstrate that all systems share a qualitatively similar electronic structure and are primarily ligand-centered pi-radicals. The calculated electron paramagnetic resonance (EPR) hyperfine coupling constants (HFCCs) for these model systems were optimized using iterative methods and were used to create accurate spectral simulations of the parent radicals [((t)Bu-DAB)Ga(I)[Pn(SiMe3)2]]* (Pn = N, P, or As) and [((t)Bu-DAB)Ga[Pn(SiMe3)2]2]* (Pn = P or As), the EPR spectra of which had not been simulated previously due to their complexity. Excellent agreement was observed between the calculated HFCCs and the optimum values, which can be considered the actual HFCCs for these systems. The computational results also revealed inconsistencies in the published EPR data of some related paramagnetic group 13-DAB complexes. 相似文献
28.
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30.
Sirpa Peräniemi Sari Hannonen Heikki Mustalahti Markku Ahlgrén 《Fresenius' Journal of Analytical Chemistry》1994,349(7):510-515
The adsorption of arsenic, selenium and mercury from aqueous solutions onto zirconium-loaded activated charcoal was studied as a function of adsorption time, amount of adsorbent, pH, concentration of adsorbates, sample volume and the oxidation states of the adsorbates. The cross-interference of the analytes was also investigated. Loaded filters were measured by energy-dispersive X-ray fluorescence spectrometry (EDXRF) and the amount of the unadsorbed analytes were determined by vapour generation atomic absorption spectrometry (VGAAS). 相似文献