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Viscoelasticandtransportpropertiesofpolymersintheliquid(solution,melt)or
liquid-like (rubber) state determine their processing and
application to a large extent and are of basic physical interest
[1-3]. An understanding of these dynamic properties at a molecular
level, therefore, is of great importance.
However,thisunderstandingiscomplicatedbythefactsthatdi?erentmotional
processes may occur on di?erent length scales and that the dynamics
are governed by universal chain properties as well as by the
special chemical structure of the monomer units [4,5]. The earliest
and simplest approach in this direction starts from Langevin
equations with solutions comprising a spectrum of relaxation modes
[1-4]. Special features are the incorporation of entropic forces
(Rouse model, [6]) which relax uctuations of reduced entropy, and
of hydrodynamic interactions (Zimm model, [7]) which couple
segmental motions via long-range back ow elds in polymer solutions,
and the inclusion of topological constraints or entanglements
(reptation or tube model, [8-10]) which are mutually imposed within
a dense ensemble of chains. Another approach, neglecting the
details of the chemical structure and
concentratingontheuniversalelementsofchainrelaxation,isbasedondynamic
scalingconsiderations[4,11].Inparticularinpolymersolutions,thisapproach
o?ers an elegant tool to specify the general trends of polymer
dynamics, although it su?ers from the lack of a molecular
interpretation. A real test of these theoretical approaches
requires microscopic methods, which simultaneously give direct
access to the space and time evolution of the segmental di?usion.
Here, quasi-elastic scattering methods play a crucial role
sincetheyallowthemeasurementofthecorrespondingcorrelationfunctions.In
particular,thehigh-resolutionneutronspinecho(NSE)spectroscopy[12-15]is
very suitable for such investigations since this method covers an
appropriate range in time (0.005)t/ns)40) and space (r/nm [15).
Furthermore, the
possibilityoflabellingbyhydrogen-deuteriumexchangeallowstheobservation
of single-chain behavior even in the melt.
With contributions by Clarke, G.; Lang, R.E.; McKinley, M.J.;
Merrick, L.P.; Rascher, W.; Richter, D.; Sofroniew, M.; Unger, T.;
Weindl, A.
A. Radulescu, L.J. Fetters, D. Richter: Polymer Driven Wax Crystal
Control Using Partially Crystalline Polymeric Materials.- F.R.
Costa, M. Saphiannikova, U. Wagenknecht, G. Heinrich: Layered
Double Hydroxide Based Polymer Nanocomposites.- S. Aoshima, S.
Kanaoka: Synthesis of Stimuli-Responsive Polymers by Living
Polymerization: Poly(N-Isopropylacrylamide) and Poly(Vinyl
Ether)s.-
mRNA Formation and Function presents a compendium of techniques
geared exclusively toward the understanding of RNA metabolism. It
will be particularly useful because a number of different organisms
and systems are employed.
Key Features
* Isolation and characterization of specific RNA binding
proteins
* RNA metabolism and associated regulatory proteins
* RNA detection and localization
* A genetic approach to RNA function
Across the world, soils are managed with an intensity and at a
geographic scale never before attempted, yet we know remarkably
little about how and why managed soils change through time.
Understanding Soil Change explores a legacy of soil change in
south-eastern North America, a region of global ecologic,
agricultural and forestry significance: from the acidic soils of
primary hardwood forests that covered the region until about 1800,
through the marked transformations affected by long-cultivated
cotton, to contemporary soils of rapidly growing and intensively
managed pine forests. These well-documented records significantly
enrich the science of ecology and pedology, and provide valuable
lessons for land management throughout the world. The book calls
for the establishment of a global network of soil-ecosystem
studies, like the invaluable Calhoun study on which the book is
based, to provide further information on sustainable land
management, vital as human demands on soil continue to increase.
Across the world, soils are managed with an intensity and at a geographic scale never before attempted, yet we know remarkably little about how and why managed soils change through time. Understanding Soil Change explores a legacy of soil change in southeastern North America, from the acidic soils of primary hardwood forests that covered the region until about 1800, through the marked transformations affected by long-cultivated cotton, to contemporary soils of rapidly growing and intensively managed pine forests. These well documented records significantly enrich the science of ecology and pedology, and provide valuable lessons for land management throughout the world. The book calls for the establishment of a global network of soil-ecosystem studies, like the invaluable Calhoun study on which the book is based, to provide further information on sustainable land management, vital as human demands on soil continue to increase.
The 1990's are an important decade, because the gynaecologist in
the 1990's has to develop a new profile. A gynaecology without
psychosomatics cannot offer an adequate answer to the modern needs
of women. European Symposium on Psychosomatic Obstetrics and
Gynaecology - in the framework of a young, dynamic tradition - was
planned by European researchers on Psychosomatic Obstetrics and
Gynaecology (Leuven, Belgium; September, 1997). cancer
(peri)menopausal and elderly woman needs and demands Therapeutical
strategie
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