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511.
Enthalpies of mixing ΔH
m
of aqueous solutions of CdCl2, CuCl2, and ZnCl2 with MgCl2 solutions were measured at ionic strengths of 1.0, 2.0, and 3.0 at 25°C. The excess enthalpy equations of Pitzer were then
fitted to the resulting ΔH
m
data. The resulting parameters are the temperature derivatives of the activity coefficient mixing parameters in the Pitzer
system. 相似文献
512.
Born P Munoz A Cavelius C Kraus T 《Langmuir : the ACS journal of surfaces and colloids》2012,28(22):8300-8308
Colloidal particles are continuously assembled into crystalline particle coatings using convective fluid flows. Assembly takes place inside a meniscus on a wetting reservoir. The shape of the meniscus defines the profile of the convective flow and the motion of the particles. We use optical interference microscopy, particle image velocimetry, and particle tracking to analyze the particles' trajectory from the liquid reservoir to the film growth front and inside the deposited film as a function of temperature. Our results indicate a transition from assembly at a static film growth front at high deposition temperatures to assembly in a precursor film with high particle mobility at low deposition temperatures. A simple model that compares the convective drag on the particles to the thermal agitation explains this behavior. Convective assembly mechanisms exhibit a pronounced temperature dependency and require a temperature that provides sufficient evaporation. Capillary mechanisms are nearly temperature independent and govern assembly at lower temperatures. The model fits the experimental data with temperature and particle size as variable parameters and allows prediction of the transition temperatures. While the two mechanisms are markedly different, dried particle films from both assembly regimes exhibit hexagonal particle packings. We show that films assembled by convective mechanisms exhibit greater regularity than those assembled by capillary mechanisms. 相似文献
513.
The introduction of three-dimensional (3D) architecture to functional materials allows for the addition of unique characteristics such as special deformation patterns, negative Poison's ratio, negative thermal expansion, controlled biological interactions, and mass transport properties. It also aids in bridging the dimensional gap between layer-by-layer (LBL) assembled nanocomposites and macroscale applications while retaining the advantages of their nanoscale organization. Fabrication of 3D microscale features by traditional techniques are often restricted to a limited variety of materials and do not include hybrid organic-inorganic nanocomposites. This work describes a new method to synthesize macroscale materials with hierarchically controlled architecture by using LBL deposition in the voids of hexagonally packed arrays of uniform microspheres and can be potentially extended to a large variety of materials. Establishing systematic techniques to produce materials with hierarchical architecture involving nano-, micro-, and potentially millimeter scale features with fairly independent control at all levels, allows for the investigation of structural influences on material properties and for the development of new practical applications due to the unusual combinations of properties that can be achieved. 相似文献
514.
Polymers have been modified, by subjecting them to reactions in solution, in the melt and in the solid state. Novel polymers with improved and optimized properties have also been created by copolymerization, chain transfer or by the design of chain termination. Even by manipulating the initiation step in polymerizations, functional and reactive groups have been introduced at the head of the polymer chain. Polymer properties have been modified by influencing physical properties of polymers by orienting, annealing and blending. 相似文献
515.
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517.
518.
Frank Würthner Stefan Brse Norbert Sewald Rainer Herges Matthias O. Senge Thorsten Bach Thomas Gottwald Thomas Kopf Kristina pehar Jens Hartung Dietmar Plattner Andreas Gansuer Martin Oestreich Reinhard Brückner Jrg Pietruszka Roderick Süßmuth Michael Müller Elmar Weinhold Andres Jschke Markus Albrecht Henning Priepke Gerhard Roth Klaus Ditrich Alexander Ernst Lars Wortmann Schering Ag 《Nachrichten aus der Chemie》2003,51(3):286-315
Die enantioselektive Synthese bleibt zentrales Thema in metallorganischen, metallfreien and bioorganischen Transformationen sowie in der industriellen organischen Chemie. Glanzpunkte zielmolekülorientierter Synthesechemie waren ein Zugang zu C60, die Route zum Diazonamid A und die Totalsynthese von Vinblastin. Mit „Pyrrolysin”︁ wurde die 22. proteinogene Aminosäure entdeckt. Trotz der immer höheren Zahl an Testsubstanzen besteht in der medizinischen Chemie ein Engpass an klinisch erfolgreichen Wirkstoffen. 相似文献
519.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献
520.
J. Ulises Reveles Patrizia Calaminici Marcela R. Beltran Andres M. Koester Shiv N. Khanna 《ChemInform》2008,39(16):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献