Dynamic Dilution Effects in Polymeric Networks

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Anne Ladegaard Larsen ◽  
Peter Sommer-Larsen ◽  
Ole Hassager
Keyword(s):  
Low Frequency ◽  
Dilution Effect ◽  
Relaxation Processes ◽  
Single Chain ◽  
Relaxation Spectra ◽  
Polymeric Networks ◽  
Dilution Effects

AbstractThe relaxation processes occurring in slightly and well-entangled polydimetylsiloxane (PDMS) networks are investigated. Swelling experiments are performed in order to determine the sol fractions. The low-frequency linear rheology of the two types of networks reveal two significant relaxation processes, namely the reptation of linear species within the network and the arm withdrawal process of star arms in the sol fraction and of dangling single-chain ends attached to the network. The relaxation spectra are influenced by the stoichiometry to a large extent due to dynamic dilution effects caused by the change in the amount of dangling arms and solubles with stoichiometry. The star arm relaxation is suppressed by washing out the sol fraction which is seen as a clear example of the dynamic dilution effect arising from the small amount of non-reactive PDMS.

Magnetic field and dilution effects on the slow relaxation of {Er3} triangle-based arsenotungstate single-molecule magnets

2020 ◽  
Vol 49 (35) ◽  
pp. 12458-12465 ◽  
Author(s):  
Hanhan Chen ◽  
Lin Sun ◽  
Jinpeng Zhang ◽  
Zikang Xiao ◽  
Pengtao Ma ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Single Molecule ◽  
Magnetic Relaxation ◽  
Slow Relaxation ◽  
Relaxation Processes ◽  
Single Molecule Magnets ◽  
Thermally Activated ◽  
Slow Magnetic Relaxation ◽  
Dilution Effects

Triangular {Er3} cluster containing POM exhibits field-induced two thermally activated relaxation processes. Whereas, the diamagnetic dilution sample indicates slow magnetic relaxation with the QTM being partially suppressed.

scholarly journals Weak-lensing clusters from HSC survey first-year data: Mitigating the dilution effect of foreground and cluster-member galaxies

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Takashi Hamana ◽  
Masato Shirasaki ◽  
Yen-Ting Lin
Keyword(s):  
Dilution Effect ◽  
Weak Lensing ◽  
First Year ◽  
Cluster Member ◽  
The Public ◽  
Photometric Redshift ◽  
Source Sample ◽  
Strategic Program ◽  
Dilution Effects ◽  
Cross Match

Abstract We present a weak-lensing cluster search using Hyper Suprime-Cam Subaru Strategic Program (HSC survey) first-year data. We pay special attention to the dilution effect of cluster-member and foreground galaxies on weak-lensing signals from clusters of galaxies; we adopt the globally normalized weak-lensing estimator which is least affected by cluster-member galaxies, and we select source galaxies by using photometric redshift information to mitigate the effect of foreground galaxies. We produce six samples of source galaxies with different low-z galaxy cuts, construct weak-lensing mass maps for each source sample, and search for high peaks in the mass maps that cover an effective survey area of ∼120 deg2. We combine six catalogs of high peaks into a sample of cluster candidates which contains 124 high peaks with signal-to-noise ratios greater than five. We cross-match the peak sample with the public optical cluster catalog constructed from the same HSC survey data to identify cluster counterparts of the peaks. We find that 107 out of 124 peaks have matched clusters within 5′ of peak positions. Among them, we define a subsample of 64 secure clusters that we use to examine dilution effects on our weak-lensing cluster search. We find that source samples with low-z galaxy cuts mitigate the dilution effect on weak-lensing signals of high-z clusters ($z \gtrsim 0.3$), and thus combining multiple peak catalogs from different source samples improves the efficiency of weak-lensing cluster searches.

scholarly journals Rapid evolution rescues hosts from competition and disease but—despite a dilution effect—increases the density of infected hosts

2017 ◽  
Vol 284 (1868) ◽  
pp. 20171970 ◽  
Author(s):  
Alexander T. Strauss ◽  
Jessica L. Hite ◽  
Marta S. Shocket ◽  
Carla E. Cáceres ◽  
Meghan A. Duffy ◽  
...  
Keyword(s):  
Phenotypic Variation ◽  
Competitive Ability ◽  
Potential Problem ◽  
Rapid Evolution ◽  
Host Density ◽  
Dilution Effect ◽  
Shared Resources ◽  
Evolutionary Response ◽  
Negative Impacts ◽  
Dilution Effects

Virulent parasites can depress the densities of their hosts. Taxa that reduce disease via dilution effects might alleviate this burden. However, ‘diluter’ taxa can also depress host densities through competition for shared resources. The combination of disease and interspecific competition could even drive hosts extinct. Then again, genetically variable host populations can evolve in response to both competitors and parasites. Can rapid evolution rescue host density from the harm caused by these ecological enemies? How might such evolution influence dilution effects or the size of epidemics? In a mesocosm experiment with planktonic hosts, we illustrate the joint harm of competition and disease: hosts with constrained evolutionary ability (limited phenotypic variation) suffered greatly from both. However, populations starting with broader phenotypic variation evolved stronger competitive ability during epidemics. In turn, enhanced competitive ability—driven especially by parasites—rescued host densities from the negative impacts of competition, disease, and especially their combination. Interspecific competitors reduced disease (supporting dilution effects) even when hosts rapidly evolved. However, this evolutionary response also elicited a potential problem. Populations that evolved enhanced competitive ability and maintained robust total densities also supported higher densities of infections. Thus, rapid evolution rescued host densities but also unleashed larger epidemics.

scholarly journals Inventory of organisms interfering with transmission of a marine trematode

2014 ◽  
Vol 94 (4) ◽  
pp. 697-702 ◽  
Author(s):  
Jennifer E. Welsh ◽  
Jaap van der Meer ◽  
Corina P.D. Brussaard ◽  
David W. Thieltges
Keyword(s):  
Crassostrea Gigas ◽  
Wadden Sea ◽  
Dilution Effect ◽  
Crangon Crangon ◽  
Trematode Parasite ◽  
Free Living ◽  
Marine Systems ◽  
Time Period ◽  
Idotea Balthica ◽  
Dilution Effects

It has increasingly been recognized that organisms can interfere with parasitic free-living stages, preventing them from infecting their specified host and thus reducing infection levels. This common phenomenon in freshwater and terrestrial systems has been termed the ‘dilution effect’ and, so far, is poorly studied in marine systems. Ten common intertidal organisms found in the Dutch Wadden Sea (North Sea) were tested to establish their effects on the free-living cercarial stages of the trematode parasite Himasthla elongata. Most species tested resulted in a significant reduction in cercariae over a 3 hr time period. The amphipod Gammarus marinus removed 100% of the cercariae, while other effective diluters were Crangon crangon (93%), Sargassum muticum (87%), Semibalanus balanoides (71%), Crassostrea gigas (67%), Hemigrapsus takanoi (>54%), Crassostrea gigas shells (44%) and Idotea balthica (24%). In contrast, mixed shells (Cerastoderma edule, Mytilus edulis, Ensis americanus and Littorina littorea) and Fucus versiculosus had no significant effect. These results suggest that dilution effects are widespread in the trematode of H. elongata, with potentially strong effects on its population dynamics.

Electrical Relaxation Studies in Fluorite Oxides

1988 ◽  
Vol 135 ◽  
Author(s):  
Partho Sarkar ◽  
Patrick S. Nicholson
Keyword(s):  
Solid Solutions ◽  
Oxygen Vacancies ◽  
Electric Modulus ◽  
Dopant Concentration ◽  
Low Frequency ◽  
Relaxation Processes ◽  
Modulus Formalism ◽  
Free Oxygen ◽  
Range Migration ◽  
Electric Modulus Formalism

AbstractElectric relaxation in CeO2-M203 (M34 sY3+, La3+) solid solutions has been investigated as a function of temperature (373K-673K) using the electric modulus formalism in the frequency range 5 to 107Hz. Two relaxation processes are observed in dilute solid solutions. The low frequency process is identified as a long range migration of free oxygen-vacancies (Process A) and the high frequency process is due to reorientation relaxation of the (MceVo) charged associates (Process B). The relaxation process is analysed using a non-exponential decay function, ø(t)=exp[-(t/τo)B] for O<β≤1, of the electric field. The observed activation enthalpy minimum as a function of dopant concentration for the Process A is explained using the concept of incomplete dissociation of oxygen-vacancies from (MceVo) defect associates and the formation of higher-order defect clusters at higher mole% M203.

Sign in / Sign up

Export Citation Format

Share Document