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971.
A. David Peklak Alessandro Butt 《Journal of polymer science. Part A, Polymer chemistry》2006,44(20):6114-6135
A detailed model describing the kinetics of living polymerization mediated by reversible addition‐fragmentation chain transfer (RAFT) in seeded emulsion polymerization is developed. The model consists of a set of population balance equations of the different radical species in the aqueous phase and in the particle phase (accounting for radical segregation) as well as for the dormant species in the particle phase. The entire population of radicals was divided into several distinguished species, based on their length and their chain end group. The model results are helpful in understanding inhibition and retardation phenomena that are typical for RAFT emulsion polymerizations. While inhibition is due to the radical loss in form of the RAFT leaving group, retardation is mostly caused by a small amount of short dormant chains in the particle phase, leading to a slight increase of radical loss via RAFT exchange with radicals entering a particle. The model results are compared to a series of experiments, using cumyl dithiobenzoate as a RAFT agent in polymerizations of styrene. The agreement between experimental and model results is good and, notably, the only parameters considered adjustable were the RAFT exchange rate coefficients. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6114–6135, 2006 相似文献
972.
973.
Michele A. Forastiere Stefano Pelli Giancarlo C. Righini Massimo Guglielmi Alessandro Martucci Munir M. Ahmad Orla McCarthy Eric Yeatman Antonello Vannucci 《Fiber and Integrated Optics》2001,20(1):29-43
Sol-gel is one of the most attractive techniques for production of silica-on-silicon integrated optical devices. In fact, it combines low cost with flexibility and ease of doping; thus, nonlinear and active compounds can be effectively included in the silica matrix. Here, the feasibility of applying the sol-gel technique to the realization of an erbium-doped optical amplifier is reported on, operating in the third telecommunication window. In particular, the development of an optimum strategy for the design and fabrication of a guiding structure in the strip-loaded configuration is described. Design optimization results, as well as fabrication results and measured characteristics, are described and discussed. 相似文献
974.
Supported, in part, by the Natural Sciences and Engineering Research Council of Canada 相似文献
975.
976.
Moro G Bonati L Bruschi M Cosentino U De Gioia L Fantucci PC Pandini A Papaleo E Pitea D Saracino GA Zampella G 《Theoretical chemistry accounts》2007,117(5-6):723-741
Computational approaches based on Molecular Dynamics simulations, Quantum Mechanical methods and 3D Quantitative Structure-Activity
Relationships were employed by computational chemistry groups at the University of Milano-Bicocca to study biological processes
at the molecular level. The paper reports the methodologies adopted and the results obtained on Aryl hydrocarbon Receptor
and homologous PAS proteins mechanisms, the properties of prion protein peptides, the reaction pathway of hydrogenase and
peroxidase enzymes and the defibrillogenic activity of tetracyclines. 相似文献
977.
978.
Alessandro Borghi Roberto Compagnoni Roberto Cossio Lorenzo Giuntini Mirko Massi Filippo Olmi Alba P. Santo Gloria Vaggelli 《Mikrochimica acta》2006,155(1-2):105-112
We present a multi-analytical and multi-instrumental approach to a petrologic study of garnets from metapelites characterized
by different metamorphic grades. The comparison between major, minor and trace element (Y) distribution in garnets crystallized
at different temperatures was performed by electron microprobe (EDS and WDS) and the Proton Induced X-ray Emission microprobe
(μ-PIXE).
Two garnet samples were selected from metapelite rocks at different metamorphic grades from the tectonic unit of Stilo, Calabrian–Peloritanian
Arc, Southern Italy. Quantitative spot analysis profiles and compositional X-ray maps of major elements and yttrium are reported.
The major element zoning of garnets is mostly characterized by a smoothed and gradual concentric variation of all elements
from core to rim. The Y concentration reveals a marked zoning with its distribution decreasing from about 7000 ppm to about
100 ppm from core to rim, respectively. The precise determination of the Y content by μ-PIXE technique allowed us to better
define the rock thermal history, by applying the Y geothermometer. In particular, a common starting temperature of about 450 °C
was calculated for the beginning of the garnet growth from all over the unit, but different temperatures in the range from
520 °C to 670 °C were estimated for the peak event in garnets from different areas, in agreement with the P–T values given
by the main rock mineral assemblages, reflecting a different metamorphic grade. 相似文献
979.
Painstaking spectrophotometric investigation was carried out on organo-metallic compounds to identify the most suitable compound for the detection of oxygen. A bis (histidinato) cobalt(II) solution was chosen, characterized by an absorption change at λ-408 nm as a function of the molecular oxygen concentration in the surrounding environment. An optical fiber system was developed that makes use of a halogen lamp as the source and an appropriate electronic circuit as a detection system. The optrode is a very small hollow fiber membrane filled with the solution and coupled with optical fibers. 相似文献
980.
In this short note we solve in the negative the three problems recently posed by Jie-Hua Mai and Wei-Hua Sun regarding the behaviour of almost periodic orbits and minimal sets of dynamical systems whose phase space is not regular. 相似文献