2020-10-21T20:12:37Zhttp://edoc.mpg.de/ac_p_oai.ploai:edoc.mpg.de:330522014-10-1343:959
On generalized Lotka-Volterra lattices
Dimakis, A.
Müller-Hoissen, F.
integrable model; Lotka-Volterra equation; Backlund transformation
Generalized matrix Lotka-Volterra lattice equations axe obtained in a systematic way from a "master equation" possessing a bicomplex formulation.
2002
Article
http://edoc.mpg.de/33052
urn:ISSN:0011-4626
Czechoslovak Journal of Physics, v.52, 1187-1193 (2002)
en
oai:edoc.mpg.de:1758802014-10-1443:959
Differential geometry of group lattices
Dimakis, A.
Muller-Hoissen, F.
2003
Article
http://edoc.mpg.de/175880
urn:ISSN:0022-2488
Journal of Mathematical Physics, v.44, 1781-1821 (2003)
en
oai:edoc.mpg.de:1759682014-10-1443:959
Riemannian geometry of bicovariant group lattices
Dimakis, A.
Muller-Hoissen, F.
2003
Article
http://edoc.mpg.de/175968
urn:ISSN:0022-2488
Journal of Mathematical Physics, v.44, 4220-4259 (2003)
en
oai:edoc.mpg.de:2065142014-10-1343:959
Extension of noncommutative soliton hierarchies
Dimakis, Aristophanes
Müller-Hoissen, Folkert
PACS 02.30.Ik; 05.45.Yv; 02.40.Gh
AKNS; KdV; KP; soliton; hierarchy; Moyal; deformation
2004
Article
http://edoc.mpg.de/206514
info:doi/10.1088/0305-4470/37/13/010
Journal of Physics A: Mathematical and General, v.37, 4069-4084 (2004)
en
oai:edoc.mpg.de:2065152014-10-1343:959
Explorations of the extended ncKP hierarchy
Dimakis, Aristophanes
Müller-Hoissen, Folkert
PACS 02.30.Ik; 05.45.Yv
KP; soliton; hierarchy; Moyal; deformation
2004
Article
http://edoc.mpg.de/206515
info:doi/10.1088/0305-4470/37/45/011
Journal of Physics A: Mathematical and General, v.37, 10899-10930 (2004)
en
oai:edoc.mpg.de:2065172007-03-1943:959
Differential calculi on quantum spaces determined by automorphisms
Dimakis, Aristophanes
Müller-Hoissen, Folkert
differential calculus; quantum group; quantum plane; automorphism
2004
Article
http://edoc.mpg.de/206517
Czechoslovak Journal of Physics, v.54, 1235-1242 (2004)
en
oai:edoc.mpg.de:2070872006-04-0743:959
Polymer Surface Melting Mediated by Capillary Waves
Herminghaus, Stephan
Seemann, Ralf
Landfester, Katharina
2004
Article
http://edoc.mpg.de/207087
Physical Review Letters, v.93, 017801-1-017801-4 (2004)
en
oai:edoc.mpg.de:2070892006-04-0743:959
Patterning of polymers: precise channel stamping by optimizing wetting properties
Seemann, Ralf
Kramer, Edward J.
Lange, Frederik F.
2004
Article
http://edoc.mpg.de/207089
New Journal of Physics, v.6, 1-10 (2004)
en
oai:edoc.mpg.de:2076022014-10-1343:959
Extension of Moyal-deformed hierarchies of soliton equations
Dimakis, Aristophanes
Müller-Hoissen, Folkert
deformation; factorization; hierarchy; KP; Moyal; soliton;
star-product; Toda lattice
Moyal-deformed hierarchies of soliton equations can be extended to larger hierarchies by including additional evolution equations with respect to the deformation parameters. A general framework is presented in which the extension is universally determined and which applies to several deformed hierarchies, including the noncommutative KP, modified KP, and Toda lattice hierarchy. We prove a Birkhoff factorization relation for the extended ncKP and ncmKP hierarchies. Also reductions of the latter hierarchies are briefly discussed. Furthermore, some results concerning the extended ncKP hierarchy are recalled from previous work.
Joint Institute for Nuclear Research
2004
Conference-Paper
http://edoc.mpg.de/207602
C. Burdik, O. Navratil, S. Posta: XI International Conference Symmetry Methods in Physics, Joint Institute for Nuclear Research (2004)
en
oai:edoc.mpg.de:2117892006-04-0743:959
Full valence band photoemission from liquid water, using EUV synchrotron radiation
Winter, B.
Weber, R.
Widdra, W.
Hertel, I. V.
Dittmar, M.
Faubel, M.
2004
Article
http://edoc.mpg.de/211789
J. Phys. Chem., v.A 108, 2625-2632 (2004)
en
oai:edoc.mpg.de:2117902006-04-0743:959
Photoemission from aqueous alkali-iodine salt solutions, using EUV synchrotron radiation
Weber, R.
Winter, B.
Schmidt, P. M.
Widdra, W.
Hertel, I. V.
Dittmar, M.
Faubel, M.
2004
Article
http://edoc.mpg.de/211790
J. Phys. Chem., v.B 108, 4729-4736 (2004)
oai:edoc.mpg.de:2117932006-04-0743:959
New design for a time-of-flight mass spectrometer with a liquid beam laser desorption ion source for the analysis of biomolecules
Charvat, A.
Lugovoj, E.
Faubel, M.
Abel, B.
2004
Article
http://edoc.mpg.de/211793
Rev. Sci. Instrum., v.75, 1209-1218 (2004)
oai:edoc.mpg.de:2118022006-04-0743:959
Characterization of extreme utltraviolet light-emitting plasmas from laser excited fluorine containing liquid polymer jet target
Abel, B.
Aßmann, J.
Faubel, M.
Gäbel, K.
Lugovoj, E.
Mann, K.
Mißalla, T.
Peth, Ch.
2004
Article
http://edoc.mpg.de/211802
J. Appl. Phys., v.95, 7619-7623 (2004)
en
oai:edoc.mpg.de:2118032006-04-0743:959
Molecular structure of surface active salt solutions: photoelectron spectroscopy and molecular dynamics simulations of aqueous Tetrabutyl-Ammonium Iodide
Winter, Bernd
Weber, Ramona
Schmidt, Philipp M.
Hertel, Ingolf V.
Faubel, Manfred
Vrbka, Lubos
Jungwirth, Pavel
2004
Article
http://edoc.mpg.de/211803
Journal of Physical Chemistry B, v.108, 14558-14564 (2004)
en
oai:edoc.mpg.de:2244632014-10-1343:959
Automorphisms of associative algebras and noncommutative geometry
Müller-Hoissen, Folkert
Dimakis, Aristophanes
A class of differential calculi is explored which is determined by a set of automorphisms of the underlying associative algebra. Several examples are presented. In particular, differential calculi on the quantum plane, the h-deformed plane and the quantum group GLp,q(2) are recovered in this way. Geometric structures like metrics and compatible linear connections are introduced.
2004
Article
http://edoc.mpg.de/224463
info:doi/10.1088/0305-4470/37/6/023
Journal of Physics A: Mathematical and General, v.37, 2307-2330 (2004)
en
oai:edoc.mpg.de:2418922014-10-1343:959
An algebraic scheme associated with the noncommutative KP hierarchy and some of its extensions
Dimakis, Aristophanes
Müller-Hoissen, Folkert
KP hierarchy; trace method; shuffle; Rota-Baxter; deformation
A well-known ansatz (`trace method') for soliton solutions turns the equations of the (noncommutative) KP hierarchy, and those of certain extensions, into families of algebraic sum identities. We develop an algebraic formalism, in particular involving a (mixable) shuffle product, to explore their structure. More precisely, we show that the equations of the noncommutative KP hierarchy and its extension (xncKP) in the case of a Moyal-deformed product, as derived in previous work, correspond to identities in this algebra. Furthermore, the Moyal product is replaced by a more general associative product. This leads to a new even more general extension of the noncommutative KP hierarchy. Relations with Rota-Baxter algebras are established.
2005
Article
http://edoc.mpg.de/241892
info:doi/10.1088/0305-4470/38/24/005
Journal of Physics A: Mathematical and General, v.38, 5453-5505 (2005)
en
oai:edoc.mpg.de:2494702006-04-0743:959
Dynamics and structure formation in thin polymer melt films
Seemann, R.
Herminghaus, S.
Neto, C.
Schlagowski, S.
Podzimek, D.
Konrad, R.
Mantz, H.
Jacobs, K.
2005
Article
http://edoc.mpg.de/249470
Journal of Physics: Condensed Matter, v.17, S267-S290 (2005)
en
oai:edoc.mpg.de:2494712006-04-0743:959
Mechanical properties of wet granular materials
Fournier, Z.
Geromichalos, D.
Herminghaus, S.
Kohonen, M. M.
Mugele, F.
Scheel, M.
Schulz, M.
Schulz, B.
Schier, C.
Seemann, R.
Skudelny, A.
2005
Article
http://edoc.mpg.de/249471
info:doi/10.1088/0953-8984/17/9/013
Journal of Physics: Condensed Matter, v.17, S477-S502 (2005)
en
oai:edoc.mpg.de:2494722006-06-1943:959
Electrowetting: a convenient way to switchable wettability patterns
Mugele, F.
Klingner, A.
Buehrle, J.
Steinhauser, D.
Herminghaus, S.
2005
Article
http://edoc.mpg.de/249472
info:doi/10.1088/0953-8984/17/9/016
Journal of Physics: Condensed Matter, v.17, S559-S576 (2005)
en
oai:edoc.mpg.de:2494732006-06-1943:959
Dynamics of wet granular matter
Herminghaus, S.
2005
Article
http://edoc.mpg.de/249473
info:doi/10.1080/00018730500167855
Advances in Physics, v.54, 221-261 (2005)
en
oai:edoc.mpg.de:2494742006-06-1943:959
Kolmogorov-Sinai Entropy of the Dilute Wet Granular Gas
Fingerle, A.
Herminghaus, S.
Zaburdaev, V.
2005
Article
http://edoc.mpg.de/249474
info:doi/10.1103/PhysRevLett.95.198001
Physical Review Letters, v.95, 198001-1-198001-4 (2005)
en
oai:edoc.mpg.de:2494752006-06-1943:959
Journal of Physics: Condensed Matter
Special issue on Wetting
Herminghaus, S.
Institute of Physics Publishing
2005
Issue
http://edoc.mpg.de/249475
urn:ISSN:0953-8984
Journal of Physics (2005)
en
oai:edoc.mpg.de:2494762006-06-1943:959
A Generic Mechanism of Sliding Friction between Charged Soft Surfaces
Herminghaus, S.
2005
Article
http://edoc.mpg.de/249476
info:doi/10.1103/PhysRevLett.95.264301
Physical Review Letters, v.95, 264301-1-264301-4 (2005)
en
oai:edoc.mpg.de:2494772006-06-1943:959
Electroactuation of Fluid Using Topographical Wetting Transitions
Baret, J.-C.
Decré, M.
Herminghaus, S.
Seemann, R.
2005
Article
http://edoc.mpg.de/249477
info:doi/10.1021/la52228b
Langmuir, v.21, 12218-12221 (2005)
en
oai:edoc.mpg.de:2494782006-06-1943:959
AFM Study of Defect-Induced Depressions of Smectic-A /Air Interface
Designolle, V.
Herminghaus, S.
Pfohl, T.
Bahr, Ch.
2005
Article
http://edoc.mpg.de/249478
info:doi/10.1021/la0525224
Langmuir, v.22, 363-368 (2005)
en
oai:edoc.mpg.de:2494802006-06-1943:959
Effect of bromide on the interfacial structure of aqueous
tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations
Winter, B.
Weber, R.
Hertel, I. V.
Faubel, M.
Vrbka, L.
Jungwirth, P.
2005
Article
http://edoc.mpg.de/249480
Chemical Physics Letters, v.410, 222-227 (2005)
en
oai:edoc.mpg.de:2494812006-06-1943:959
Applications, features, and mechanistic aspects of liquid water beam desorption mass spectrometry
Abel, B.
Charvat, A.
Diederichsen, U.
Faubel, M.
Girmann, B.
Niemeyer, J.
Zeeck, A.
2005
Article
http://edoc.mpg.de/249481
International Journal of Mass Spectrometry, v.243, 177-188 (2005)
en
oai:edoc.mpg.de:2494822006-06-1943:959
Electron Binding Energies of Aqueous Alkali and Halide Ions: EUV Photoelectron Spectroscopy of Liquid Solutions and Combined Ab Initio and Molecular Dynamics Calculations
Winter, B.
Weber, R.
Hertel, I. V.
Faubel, M.
Jungwirth, P.
Brown, E. C.
Bradfoth, S. E.
2005
Article
http://edoc.mpg.de/249482
Journal of the American Chemical Society, v.127, 2703-2714 (2005)
en
oai:edoc.mpg.de:2496462006-06-1943:959
Brownian motion of actin filaments in confining microchannels
Köster, S.
Steinhauser, D.
Pfohl, T.
2005
Article
http://edoc.mpg.de/249646
Journal of Physics: Condensed Matter, v.17, S4091-S4104 (2005)
en
oai:edoc.mpg.de:2496472006-06-1943:959
Microfluidics of soft matter investigated by small-angle scattering
Otten, A.
Köster, S.
Struth, B.
Snigirev, A.
Pfohl, T.
2005
Article
http://edoc.mpg.de/249647
info:doi/10.1107/S0909049505013580
Journal of Synchroton Radiation, v.12, 745-750 (2005)
de
oai:edoc.mpg.de:2501292014-10-1343:959
Algebraic identities associated with KP and AKNS hierarchies
Dimakis, Aristophanes
Müller-Hoissen, Folkert
We present an overview of recent results (nlin.SI/0501003, J.Phys.A: Math.Gen. 38 (2005) 5453).
An old (``trace") method of Okhuma and Wadati to generate soliton solutions of the KP equation via a formal power series ansatz leads to a correspondence between algebraic partial sum identities and the equations of the classical KP hierarchy (where the fields are allowed to have values in an arbitrary associative algebra). Moreover, such a correspondence can be achieved by abstracting from the partial sum calculus to an algebraic scheme, which in particular involves a (mixable) shuffle product and makes contact with Rota-Baxter algebras. Furthermore, larger sets of identities in this algebra correspond to extensions of the KP hierarchy in the case where the associative product is a Moyal-product or a certain generalization of it.
2005
Article
http://edoc.mpg.de/250129
Czechoslovak Journal of Physics, v.55, 1385-1390 (2005)
en
oai:edoc.mpg.de:2633862007-03-2943:959
Evolution of DNA compaction in microchannels
Dootz, R.
Otten, A.
Köster, S.
Struth, B.
Pfohl, T.
2006
Article
http://edoc.mpg.de/263386
info:doi/doi:10.1088/0953-8984/18/18/S10
Journal of Physics: Condensed Matter, v.18, S639-S652 (2006)
en
oai:edoc.mpg.de:2634312006-04-2043:959
Generation of monodisperse gel emulsions in a microfluidic device
Priest, G.
Herminghaus, S.
Seemann, R.
2006
Article
http://edoc.mpg.de/263431
info:doi/10.1063/1.2164393
Applied Physics Letter, v.88, 024106-1-024106-3 (2006)
en
oai:edoc.mpg.de:2781422006-07-0343:959
Capillary filling of miniaturized sources for electrospray mass spectrometry
Arscott, S.
Gaudet, M.
Brinkmann, M.
Ashcroft, A. E.
Blossey, R.
2006
Article
http://edoc.mpg.de/278142
info:doi/10.1088/0953-8984/18/18/S13
Journal of Physics: Condensed Matter, v.18, S677-S690 (2006)
en
oai:edoc.mpg.de:2781432006-07-0343:959
Surfactant-induced nematic wetting layer at a thermotropic liquid crystal/water interface
Bahr, C.
2006
Article
http://edoc.mpg.de/278143
info:doi/10.1103/PhysRevE.73.030702
Physical Rewiew E, v.73, 030702-1-030702-4 (2006)
en
oai:edoc.mpg.de:2781452006-07-0343:959
Raman and surface enhanced Raman microscopy of microstructured PEI/DNA multilayers
Dootz, R.
Nie, J.
Du, B.
Herminghaus, S.
Pfohl, T.
2006
Article
http://edoc.mpg.de/278145
Langmuir, v.22, 1735-1741 (2006)
en
oai:edoc.mpg.de:2781462006-07-0343:959
A columnar phase of dendritic lipid-based cationic liposome-DNA complexes for gene delivery: hexagonally ordered cylindrical micelles embedded in a DNA honeycomb lattice
Ewert, K. K.
Evans, H. M.
Zidovska, A.
Bouxsein, N. F.
Ahmad, C. R.
2006
Article
http://edoc.mpg.de/278146
Journal of the American Chemical Society, v.128, 3998-4006 (2006)
en
oai:edoc.mpg.de:2781472007-03-2943:959
Domain growth dynamics and local viscosity in stratifying foam films
Heinig, P.
Beltran, C. M.
Langevin, D.
2006
Article
http://edoc.mpg.de/278147
info:doi/10.1103/PhysRevE.73.051607
Physical Review E, v.73, 051607-1-051607-8 (2006)
en
oai:edoc.mpg.de:2781492006-07-0343:959
Surmounting Barriers: The Benefit of Hydrodynamic Interactions
Lutz, C.
Reichert, M.
Stark, H.
Bechinger, C.
2006
Article
http://edoc.mpg.de/278149
Europhysics Letters, v.74, 719-725 (2006)
en
oai:edoc.mpg.de:2781502006-07-0343:959
Superdiffusion in a Honeycomb Billiard
Schmiedeberg, M.
Stark, H.
2006
Article
http://edoc.mpg.de/278150
info:doi/10.1103/PhysRevE.73.031113
Physical Review E, v.73, 031113-1-031113-9 (2006)
en
oai:edoc.mpg.de:2781512006-07-0343:959
Electron binding energies of hydrated H3O+ and OH-: Photoelectron spectroscopy of aqueous acid and base solutions combined with electronic structure calculations
Winter, B.
Faubel, M.
Hertel, I. V.
Pettenkofer, C.
Bradforth, S. E.
Jagoda-Cwiklik, B.
Cwiklik, L.
Jungwirth, P.
2006
Article
http://edoc.mpg.de/278151
Journal of the American Chemical Society, v.128, 3864-3865 (2006)
en
oai:edoc.mpg.de:2781522006-07-0343:959
Photoemission from liquid aqueous solutions
Winter, B.
Faubel, M.
2006
Article
http://edoc.mpg.de/278152
Chemical Reviews, v.106, 1176-1211 (2006)
en
oai:edoc.mpg.de:2808522006-07-0443:959
New multivalent cationic lipids reveal bell curve for transfection efficiency versus membrane charge density: lipid-DNA complexes for gene delivery
Ahmad, A.
Evans, H. E.
Ewert, K.
George, C. X.
Samuel, C. E.
Safinya, C. R.
2005
Article
http://edoc.mpg.de/280852
Journal of Gene Medicine, v.7, 739-748 (2005)
en
oai:edoc.mpg.de:2808532006-07-0443:959
Stability of liquid channels or filaments in the presence of line tension
Brinkmann, M.
Kierfeld, J.
Lipowsky, R.
2005
Article
http://edoc.mpg.de/280853
Journal of Physics: Codensed Matter, v.17, 2349-2364 (2005)
en
oai:edoc.mpg.de:2808542006-07-0443:959
Domain shape relaxation and local viscosity in stratifying foam films
Heinig, P.
Langevin, D.
2005
Article
http://edoc.mpg.de/280854
European Physical Journal E, v.18, 483-488 (2005)
en
oai:edoc.mpg.de:2808572006-07-0443:959
Wetting, budding, and fusion-morphological transitions of soft surfaces
Lipowsky, R.
Brinkmann, M.
Dimova, R.
Haluska, C.
Kierfeld, J.
Shillcock, J.
2005
Article
http://edoc.mpg.de/280857
Journal of Physics: Condensed Matter, v.17, S2885-S2902 (2005)
en
oai:edoc.mpg.de:2808722006-07-0543:959
Wetting morphologies at microstructured surfaces
Seemann, R.
Brinkmann, M.
Kramer, E. J.
Lange, F. F.
Lipowsky, R.
2005
Article
http://edoc.mpg.de/280872
Proccedings of the National Academy of Science USA, v.102, 1848-1852 (2005)
en
oai:edoc.mpg.de:2808762006-07-0543:959
Droplets, bubbles, and vesicles at chemically structured surfaces
Lipowsky, R.
Brinkmann, M.
Dimova, R.
Franke, T.
Kierfeld, J.
Zhang, X. Z.
2005
Article
http://edoc.mpg.de/280876
Journal of Physics: Condensed Matter, v.17, S537-S558 (2005)
oai:edoc.mpg.de:2808812006-07-0543:959
Trendbericht: Mikrofluidik
Jacobs, K.
Seemann, R.
Kuhlmann, H.
2005
Article
http://edoc.mpg.de/280881
Nachrichten aus der Chemie, v.53, 300-304 (2005)
de
oai:edoc.mpg.de:2808822006-07-0543:959
Wettability control of droplet deposition and detachment
Baret, J.-C.
Brinkmann, M.
2006
Article
http://edoc.mpg.de/280882
Physical Review Letters, v.96, 146106-1-146106-4 (2006)
en
oai:edoc.mpg.de:2809062014-10-1343:959
Functional representations of integrable hierarchies
Dimakis, Aristophanes
Müller-Hoissen, Folkert
integrable system, hierarchy, AKNS, KP
We consider a general framework for integrable hierarchies in Lax form and derive certain universal equations from which 'functional representations' of particular hierarchies (like KP, discrete KP, mKP, AKNS), i.e. formulations in terms of functional equations, are systematically and quite easily obtained. The formalism genuinely applies to hierarchies where the dependent variables live in a noncommutative (typically matrix) algebra. The obtained functional representations can be understood as 'noncommutative' analogs of 'Fay identities' for the KP hierarchy.
2006
Article
http://edoc.mpg.de/280906
Journal of Physics A: Mathematical and General, v.39, 9169-9186 (2006)
en
oai:edoc.mpg.de:2895002007-03-2943:959
Freezing and Melting of a Colloidal Adsorbate on a 1D Quasicrystalline Substrate
Schmiedeberg, M.
Roth, J.
Stark, H.
2006
Article
http://edoc.mpg.de/289500
info:doi/10.1103/PhysRevLett.97.158304
Physical Review Letters, v.97, 158304-1-158304-4 (2006)
en
oai:edoc.mpg.de:2895062007-03-2943:959
Unclustering Transition in Freely Cooling Wet Granular Matter
Fingerle, A.
Herminghaus, S.
2006
Article
http://edoc.mpg.de/289506
info:doi/10.1103/PhysRevLett.97.078001
Physical Review Letters, v.97, 078001-1-078001-4 (2006)
en
oai:edoc.mpg.de:2895072007-03-2943:959
Controlled electrocoalescence in microfluidics: Targeting a single lamella
Priest, C.
Herminghaus, S.
Seemann, R.
2006
Article
http://edoc.mpg.de/289507
info:doi/10.1063/1.2357039
Applied Physics Letters, v.89, 134101-1-134101-3 (2006)
en
oai:edoc.mpg.de:2895082007-03-2943:959
Freezing of Polymer Thin Films and Surfaces: The Small Molecular Weight Puzzle
Seemann, R.
Jacobs, K.
Landfester, K.
Herminghaus, S.
2006
Article
http://edoc.mpg.de/289508
info:doi/10.1002/polb.20920
Journal of Polymer Science: Part B, v.44, 2968-2979 (2006)
en
oai:edoc.mpg.de:2934252007-01-0543:959
Rapid Prototyping of X-ray Microdiffraction Compatible Continuous Microflow Foils
Dootz, R.
Evans, H
Köster, S.
Pfohl, T.
2006
Article
http://edoc.mpg.de/293425
info:doi/10.1002/smll.200600288
Small, v.3, 96-100 (2006)
en
oai:edoc.mpg.de:2934262007-01-0543:959
Random Walk Model with Waiting Times Depending on the Jump Length
Zaburdaev, V. Yu.
2006
Article
http://edoc.mpg.de/293426
info:doi/10.1007/s10955-006-9104-z
Journal of Statistical Physics, v.123, 871-881 (2006)
en
oai:edoc.mpg.de:2934272007-03-2943:959
Dewetting Through Nucleation
Herminghaus, S.
Brochard, F.
2006
Article
http://edoc.mpg.de/293427
info:doi/10.1016/j.crhy.2006.10.021
Comptes Rendus Physique, v.7, 1073-1081 (2006)
en
oai:edoc.mpg.de:2936742007-01-1043:959
Visualization of flow-aligned type I collagen self-assembly in tunable pH-gradients
Köster, S.
Leach, J. B.
Struth, B.
Pfohl, T.
Wong, J. Y.
2006
Article
http://edoc.mpg.de/293674
Langmuir, v.23, 357-359 (2006)
en
oai:edoc.mpg.de:2937152007-03-1943:959
From AKNS to derivative NLS hierarchies via deformations of associative products
Dimakis, Aristophanes
Müller-Hoissen, Folkert
Using deformations of associative products, derivative nonlinear Schrödinger (DNLS) hierarchies are recovered as AKNS-type hierarchies. Since the latter can also be formulated as Gelfand-Dickey-type Lax hierarchies, a recently developed method to obtain 'functional representations' can be applied. We actually consider hierarchies with dependent variables in any (possibly noncommutative) associative algebra, e.g., an algebra of matrices of functions. This also covers the case of hierarchies of coupled derivative NLS equations.
2006
Article
http://edoc.mpg.de/293715
info:doi/10.1088/0305-4470/39/45/010
Journal of Physics A: Mathematical and General, v.39, 14015-14033 (2006)
en
oai:edoc.mpg.de:2937432014-10-1343:959
From nonassociativity to solutions of the KP hierarchy
Dimakis, Aristophanes
Müller-Hoissen, Folkert
integrable hierarchy, KP, nonassociativity, Riccati equation, soliton
A recently observed relation between 'weakly nonassociative' algebras A (for which the associator (A,A^2,A) vanishes) and the KP hierarchy (with dependent variable in the middle nucleus A' of A is recalled. For any such algebra there is a nonassociative hierarchy of ODEs, the solutions of which determine solutions of the KP hierarchy. In a special case, and with A' a matrix algebra, this becomes a matrix Riccati hierarchy which is easily solved. The matrix solution then leads to solutions of the scalar KP hierarchy. We discuss some classes of solutions obtained in this way.
2006
Article
http://edoc.mpg.de/293743
info:doi/10.1007/s10582-006-0412-z
Czechoslovak Journal of Physics, v.56, 1123-1130 (2006)
en
oai:edoc.mpg.de:3053842007-03-2143:959
Volume phase transition of "smart" microgels in bulk solution and adsorbed at an interface: A combined AFM, dynamic light, and small angle neutron scattering study
Höfl, S.
Zitzler, L.
Hellweg, T.
Herminghaus, S.
Mugele, F.
2006
Article
http://edoc.mpg.de/305384
info:doi/10.1016/j.polymer.2006.10.026
Polymer, v.48, 245-254 (2006)
en
oai:edoc.mpg.de:3053882007-03-2143:959
Dry and wet granular shock waves
Zaburdaev, V. Yu.
Herminghaus, S.
2007
Article
http://edoc.mpg.de/305388
info:doi/10.1103/PhysRevE.75.031304
Physical Review E, v.75, 031304-1-031304-11 (2007)
en
oai:edoc.mpg.de:3092192014-10-1343:959
With a Cole-Hopf transformation to solutions of the noncommutative KP hierarchy in terms of Wronski matrices
Dimakis, Aristophanes
Müller-Hoissen, Folkert
integrable system; KP hierarchy; quasideterminant; nonassociative algebra
In case of the KP hierarchy where the dependent variable takes values in an (arbitrary) associative algebra R, it is known that there are solutions which can be expressed in terms of quasideterminants of a Wronski matrix which solves the linear heat hierarchy. We obtain these solutions without the help of quasideterminants in a simple way via solutions of matrix KP hierarchies (over R) and by use of a Cole-Hopf transformation. For this class of exact solutions we work out a correspondence with 'weakly nonassociative' algebras.
2007
Article
http://edoc.mpg.de/309219
info:doi/10.1088/1751-8113/40/17/F02
Journal of Physics A: Mathematical and Theoretical, v.40, F321-F329 (2007)
en
oai:edoc.mpg.de:3180532014-10-1343:959
Burgers and Kadomtsev-Petviashvili hierarchies: A functional representation approach
Dimakis, Aristophanes
Müller-Hoissen, Folkert
Functional representations of (matrix) Burgers and potential KP (pKP) hierarchies (and others), as well as some corresponding Bäcklund transformations, can be obtained surprisingly simply from a "discrete" functional zero curvature equation. We use these representations to show that any solution of a Burgers hierarchy is also a solution of the pKP hierarchy. Moreover, the pKP hierarchy can be expressed in the form of an inhomogeneous Burgers hierarchy. In particular, this leads to an extension of the Cole-Hopf transformation to the pKP hierarchy. Furthermore, these hierarchies are solved by the solutions of certain functional Riccati equations.
2007
Article
http://edoc.mpg.de/318053
Theoretical and Mathematical Physics, v.152, 933-947 (2007)
en
oai:edoc.mpg.de:3180542014-10-1343:959
A new approach to deformation equations of noncommutative KP hierarchies
Dimakis, Aristophanes
Müller-Hoissen, Folkert
Partly inspired by Sato's theory of the Kadomtsev-Petviashvili (KP) hierarchy, we start with a quite general hierarchy of linear ordinary differential equations in a space of matrices and derive from it a matrix
Riccati hierarchy. The latter is then shown to exhibit an underlying 'weakly nonassociative' (WNA) algebra structure, from which we can conclude, referring to previous work, that any solution of the Riccati system also solves the potential KP hierarchy (in the corresponding matrix algebra). We then turn to the case where the components of the matrices are multiplied using a (generalized) star product. Associated with the deformation parameters, there are additional symmetries (flow equations) which enlarge the respective
KP hierarchy. They have a compact formulation in terms of the WNA structure. We also present a formulation of the KP hierarchy equations themselves as deformation flow equations.
2007
Article
http://edoc.mpg.de/318054
info:doi/10.1088/1751-8113/40/27/010
Journal of Physics A: Mathematical and Theoretical, v.40, 7573-7596 (2007)
en
oai:edoc.mpg.de:3398402008-03-1043:959
Fluidics of a Nanogap
Brinkmann, M.
Blossey, R.
Marcon, L.
Stiévenard, D.
Dufrêne, Y. F.
Melnyk, O.
We have determined the filling properties of nanogaps with chemically heterogeneous walls. The quantitative criteria we present allow the prediction of the liquid loading of the nanostructure. They can easily be applied in combination with contact-angle measurements on planar substrates of the nanogap materials. We present an application of the theory to a recently developed nanogap biosensor. Chemical force microscopy (CFM) is employed to characterize the initial silanol properties of the gap. The functionality of the complex surface chemistry of the biosensor is demonstrated by the observation of functionalized nanoparticles in the gap with its resulting characteristic current-voltage relationship.
2006
Article
http://edoc.mpg.de/339840
info:doi/10.1021/la0611357
Langmuir, v.22, 9784-9788 (2006)
en
oai:edoc.mpg.de:3398582008-03-1043:959
The viscous drag of spheres and filaments moving in membranes or monolayers
Fischer, M.
Dhar, P.
Heinig, P.
We numerically calculate the drag on a sphere or a filament immersed in an incompressible viscous monolayer or membrane on one, or between two, viscous infinitely deep bulk phases. We show that contributions due to the Marangoni effect of the monolayer or membrane account for a significant part of the total drag. Effects of protrusion of objects into the three-dimensional fluids adjacent to the monolayer and membrane are investigated. Known analytical expressions in the limit of a very viscous membrane or monolayer are recovered by our numerics. A sphere in a membrane exhibits maximal drag when symmetrically immersed with the equator coinciding with the membrane plane. No discontinuity of the drag arises when the sphere is totally immersed into the subphase and detaches from the monolayer. Effects of protrusion are more important for objects moving in a membrane or monolayer of low surface viscosity. At large surface shear viscosity protrusions must be larger than the length defined by the ratio of surface to bulk viscosities to alter the drag on the object. Our calculations may be useful for the measurement of hydrodynamic radii of lipid rafts in membranes and for electrocapillary effects of spheres immersed in a surface.
2006
Article
http://edoc.mpg.de/339858
info:doi/10.1017/S002211200600022X
Journal of Fluid Mechanics, v.558, 451-475 (2006)
en
oai:edoc.mpg.de:3398642008-03-1043:959
Self-organization in phase separation of a lyotropic liquid crystal into cellular, network and droplet morphologies
Iwashita, Yasutaka
Tanaka, Hajime
Phase separation is one of the most fundamental physical phenomena that controls the morphology of heterogeneous structures. Phase separation of a binary mixture of simple liquids produces only two morphologies: a bicontinuous or a droplet structure in the case of a symmetric or an asymmetric composition, respectively. For complex fluids, there is a possibility to produce other interesting morphologies. We found that a network structure of the minority phase can also be induced transiently on phase separation if the dynamics of the minority phase are much slower than those of the majority phase. Here we induce a cellular structure of the minority phase intentionally with the help of its smectic ordering, using phase separation of a lyotropic liquid crystal into the isotropic and smectic phase. We can control the three morphologies, cellular, network and droplet structures, solely by changing the heating rate. We demonstrate that the kinetic interplay between phase separation and smectic ordering is a key to the morphological selection. This may provide a new route to the formation of network and cellular morphologies in soft materials.
2006
Article
http://edoc.mpg.de/339864
info:doi/10.1038/nmat1580
Nature Materials, v.5, 147-152 (2006)
en
oai:edoc.mpg.de:3398712008-03-1043:959
Free Cooling of the One-Dimensional Wet Granular Gas
Zaburdaev, V. Yu.
Brinkmann, M.
Herminghaus, S.
The free cooling behavior of a wet granular gas is studied in one dimension. We employ a particularly simple model system in which the interaction of wet grains is characterized by a fixed energy loss assigned to each collision. Macroscopic laws of energy dissipation and cluster formation are studied on the basis of numerical simulations and mean-field analytical calculations. We find a number of remarkable scaling properties which may shed light on earlier unexplained results for related systems.
2006
Article
http://edoc.mpg.de/339871
info:doi/10.1103/PhysRevLett.97.018001
Physical Review Letters, v.97, 018001-1-018001-4 (2006)
en
oai:edoc.mpg.de:3398762008-03-1343:959
Surface Triple Points and Multiple-Layer Transitions Observed by Tuning the Surface Field at Smectic Liquid-Crystal–Water Interfaces
Bahr, Christian
We present an ellipsometric study of the interface between a smectic liquid crystal and water in the presence of a nonionic surfactant. The surfactant concentration serves as a handle to tune the surface field. For sufficiently large surfactant concentrations, a smectic phase is present at the interface in the temperature range above the smectic-A–isotropic bulk transition; when the bulk transition is approached, the thickness of this surface phase grows via a series of layer-by-layer transitions at which single smectic layers are formed. At lower surfactant concentrations, transitions appear at which the thickness of the surface phase jumps by multiple smectic layers, thereby implying the existence of triple points at which surface phases with different smectic layer numbers coexist. This is the first experimental demonstration of such surface triple points which are predicted by theoretical models.
2007
Article
http://edoc.mpg.de/339876
info:doi/10.1103/PhysRevLett.99.057801
Physical Review Letters, v.99, 057801-1-057801-4 (2007)
en
oai:edoc.mpg.de:3398792008-03-1043:959
Transport Dynamics in Open Microfluidic Grooves
Baret, Jean-Christophe
Decré, M. J.
Herminghaus, Stephan
Seemann, Ralf
In microscopic rectangular grooves various liquid wetting morphologies can be found, depending on the wettability and details of the geometry. When these morphologies are combined with a method to vary the apparent contact angle reversibly, transitions between droplike objects and elongated liquid filaments can be induced. Liquid can thus be transported on demand along the grooves. The dynamics of liquid filaments advancing into grooves as well as receding from grooves has been studied, varying the contact angle using the electrowetting effect. The dynamics of the receding filament is purely capillarity driven and depends only on the contact angle, the viscosity of the liquid, and the geometry of the groove. The length and the dynamics of the advancing filaments, on the other hand, are strongly dependent on the ionic content of the liquid and the applied ac voltage.
2007
Article
http://edoc.mpg.de/339879
info:doi/10.1021/la063584c
Langmuir, v.23, 5200-5204 (2007)
en
oai:edoc.mpg.de:3398842008-03-1343:959
Hydrodynamic Flow-Mediated Protein Sorting on the Cell Surface of Trypanosomes
Engstler, Markus
Pfohl, Thomas
Herminghaus, Stephan
Boshart, Michael
Wiegertjes, Geert
Heddergott, Niko
Peter Overath, Peter
The unicellular parasite Trypanosoma brucei rapidly removes host-derived immunoglobulin (Ig) from its cell surface, which is dominated by a single type of glycosylphosphatidylinositol-anchored variant surface glycoprotein (VSG). We have determined the mechanism of antibody clearance and found that Ig-VSG immune complexes are passively sorted to the posterior cell pole, where they are endocytosed. The backward movement of immune complexes requires forward cellular motility but is independent of endocytosis and of actin function. We suggest that the hydrodynamic flow acting on swimming trypanosomes causes directional movement of Ig-VSG immune complexes in the plane of the plasma membrane, that is, immunoglobulins attached to VSG function as molecular sails. Protein sorting by hydrodynamic forces helps to protect trypanosomes against complement-mediated immune destruction in culture and possibly in infected mammals but likewise may be of functional significance at the surface of other cell types such as epithelial cells lining blood vessels.
2007
Article
http://edoc.mpg.de/339884
info:doi/10.1016/j.cell.2007.08.046
Cell, v.131, 279-281 (2007)
en
oai:edoc.mpg.de:3398872008-03-1043:959
X-ray Microdiffraction on Flow-controlled Biomolecular Assemblies
Evans, H. M.
Dootz, R.
Köster, S.
Struth, B
Pfohl, T.
The study of liquid crystalline assemblies, with an emphasis on biological phenomena, is now accessible using newly developed microdevices integrated with X-ray analysis capability. Many biological systems can be described in terms of gradients, mixing, and confinement, all of which can be mimicked with the use of appropriate microfluidic designs. The use of hydrodynamic focusing creates well-defined mixing conditions that vary depending on parameters such as device geometry, and can be quantified with finite element modelling.We describe experiments in which geometry and strain rate induce finite changes in liquid crystalline orientation. We also demonstrate the online supramolecular assembly of lipoplexes. The measurement of lipoplex orientation as a function of flow velocity allows us to record a relaxation process of the lipoplexes, as evidenced by a remarkable 4-fold azimuthal symmetry. All of these processes are accessible due to the intentional integration of design elements in the microdevices.
2007
Article
http://edoc.mpg.de/339887
Bulletin of the Polish Academy of Sciences: Technical Sciences, v.55, 217-227 (2007)
en
oai:edoc.mpg.de:3398922008-03-1043:959
Thermal Noise Influences Fluid Flow in Thin Films during Spinodal Dewetting
Fetzer, R.
Rauscher, M.
Seemann, R.
Jacobs, K.
Mecke, K.
Experiments on dewetting thin polymer films confirm the theoretical prediction that thermal noise can
strongly influence characteristic time scales of fluid flow and cause coarsening of typical length scales.
Comparing the experiments with deterministic simulations, we show that the Navier-Stokes equation has
to be extended by a conserved bulk noise term to accomplish the observed spectrum of capillary waves.
Because of thermal fluctuations the spectrum changes from an exponential to a power law decay for large
wave vectors. Also the time evolution of the typical wave vector of unstable perturbations exhibits noiseinduced
coarsening that is absent in deterministic hydrodynamic flow.
2007
Article
http://edoc.mpg.de/339892
info:doi/10.1103/PhysRevLett.99.114503
Physical Review Letters, v.99, 114503-1-114503-4 (2007)
en
oai:edoc.mpg.de:3398982008-03-1543:959
Chaoticity of the wet granular gas
Fingerle, A.
Herminghaus, S.
Zaburdaev, V. Yu.
In this work we derive an analytic expression for the Kolmogorov-Sinai entropy of dilute wet granular
matter, valid for any spatial dimension. The grains are modeled as hard spheres and the influence of the wetting
liquid is described according to the capillary model, in which dissipation is due to the hysteretic cohesion force
of capillary bridges. The Kolmogorov-Sinai entropy is expanded in a series with respect to density. We find a
rapid increase of the leading term when liquid is added. This demonstrates the sensitivity of the granular
dynamics to humidity, and shows that the liquid significantly increases the chaoticity of the granular gas.
2007
Article
http://edoc.mpg.de/339898
info:doi/10.1103/PhysRevE.75.061301
Physical Review E, v.75, 061301-1-061301-12 (2007)
en
oai:edoc.mpg.de:3399082008-03-1043:959
Relativistic fluctuation theorems
Fingerle, Axel
2007
Article
http://edoc.mpg.de/339908
info:doi/10.1016/j.crhy.2007.05.015
Comptes Rendus Physique, v.8, 696-713 (2007)
en
oai:edoc.mpg.de:3399162009-03-1343:959
Equation of state of wet granular matter
Fingerle, A.
Herminghaus, S.
2008
Article
http://edoc.mpg.de/339916
info:doi/10.1103/PhysRevE.77.011306
Physical Review E, v.77, 011306-1-011306-21 (2008)
en
oai:edoc.mpg.de:3399272008-03-1343:959
Spontaneous Onion-Structure Formation from Planar Lamellar Nuclei
Iwashita, Yasutaka
Tanaka, Hajime
Nucleation and growth are a basic elementary process of ordering. The nucleation process is controlled
by a competition between interfacial and bulk energy. Thus an ordered structure of a nucleus at its birth is
not necessarily the most stable thermodynamically: Ostwald step rule. In addition to this, we found the
topological transformation of nuclei from the most stable bulk structure (planar lamella) to a metastable
one (onion) in a lyotropic liquid crystal. This indicates that the fate of nuclei of low-dimensional internal
order can also be seriously affected by an additional competition between interfacial and elastic
deformation energy.
2007
Article
http://edoc.mpg.de/339927
info:doi/10.1103/PhysRevLett.98.145703 PACS
Physical Review Letters, v.98, 145703-1-145703-4 (2007)
en
oai:edoc.mpg.de:3399292008-03-1343:959
Crossover in the wetting behavior at surfactant-laden liquid-crystal–water interfaces: Experiment and theory
Kadivar, E.
Bahr, Ch.
Stark, H.
The behavior of a nematic liquid crystal at a surfactant-laden interface to an aqueous phase is studied under the condition of homeotropic anchoring. It is shown that with decreasing surfactant concentration the system shifts from surface-enhanced to surface-decreased order, i.e., the behavior changes from complete nematic wetting when the nematic–isotropic phase transition is approached from above to a different wetting behavior below the transition, characterized by a considerably decreased Maier-Saupe order parameter at the interface. The experimental behavior is analyzed within the framework of the Landau–de Gennes theory supplemented by a surface free energy, in which the wetting behavior is controlled by the magnitude of the anchoring strength and the preferred surface order parameter in comparison to the bulk order parameter. The theoretical modeling is able to account for all experimental observations.
2007
Article
http://edoc.mpg.de/339929
info:doi/10.1103/PhysRevE.75.061711
Physical Review E, v.75, 061711-1-061711-9 (2007)
en
oai:edoc.mpg.de:3399352008-03-1343:959
Dewetting of Liquid Filaments in Wedge-Shaped Grooves
Khare, Krishnacharya
Brinkmann, Martin
Law, Bruce M.
Gurevich, Evgeny L.
Herminghaus, Stephan
Seemann, Ralf
The dewetting of liquid filaments in linear grooves of a triangular cross section is studied experimentally and theoretically. Homogeneous filaments of glassy polystyrene (PS) are prepared in triangular grooves in a nonequilibrium state. At elevated temperatures, the molten PS restores its material contact angle with the substrate. Liquid filaments with a convex liquid-vapor interface decay into isolated droplets with a characteristic spacing depending on the wedge geometry, wettability, and filament width. This instability is driven by the interplay of local filament width and Laplace pressure and constitutes a wide class of 1D instabilities that also include the Rayleigh-Plateau instability as a special case. Our results show an accurately exponential buildup of the instability, suggesting that fluctuations have a minor influence in our system.
2007
Article
http://edoc.mpg.de/339935
info:doi/10.1021/la701515u
Langmuir, v.23, 12138-12141 (2007)
en
oai:edoc.mpg.de:3404512008-03-1343:959
Switching Liquid Morphologies on Linear Grooves
Khare, Krishnacharya
Herminghaus, Stephan
Baret, Jean-Christophe
Law, Bruce M.
Brinkmann, Martin
Seemann, Ralf
The morphology of liquids confined to linear micrometer-sized grooves of triangular and rectangular cross section is studied for different substrate wettabilities. Depending on the wettability and exact geometry, either droplike morphologies or elongated liquid filaments represent the generic equilibrium structures on the substrate. Upon changing the apparent contact angle of aqueous drops by electrowetting, we are able to trigger the transition between elongated filaments and droplets. In the case of rectangular grooves, this transition allows us to advance liquid reversibly into the grooves while crossing a certain threshold contact angle. In triangular grooves, however, these elongated filaments undergo a dynamic instability when the contact angle returns to a value above the filling threshold. The different filling and drainage behavior is explained by specific aspects of the triangular and rectangular groove geometry.
2007
Article
http://edoc.mpg.de/340451
info:doi/10.1021/la701899u
Langmuir, v.23, 12997-13006 (2007)
en
oai:edoc.mpg.de:3407152008-03-1343:959
Fluctuations of Single Confined Actin Filaments
Köster, S.
Stark, H.
Pfohl, T.
Kierfeld, J.
Thermal fluctuations of individual actin filaments confined in rectangular microchannels with dimensions similar to the mesh size of the cytoskeleton in eukaryotic cells are studied experimentally using fluorescence microscopy and theoretically by a combination of analytical methods and Monte Carlo simulations. Compared to freely fluctuating filaments, long filaments confined in narrow channels exhibit enhanced tangent correlations and a characteristic shape of their correlation function. The tangent correlation function is calculated analytically by approximating the confining geometry by a parabolic potential. This approximation is validated by Monte Carlo simulations. For the quantitative analysis of experimental data additional corrections for image analysis effects have to be included, for which we provide a modified analytical approximation formula which is corroborated by simulations. This allows us to obtain both the persistence length LP describing the bending rigidity of the polymer and the deflection length λ characterizing confinement effects from fits to the experimental data. Our results confirm the scaling relation λ ∝ d2/3 between the deflection length and the channel width d.
2007
Article
http://edoc.mpg.de/340715
Biophysical Reviews and Letters, v.2, 155-166 (2007)
oai:edoc.mpg.de:3407262008-03-1343:959
pH-Induced Protonation of Lysine in Aqueous Solution Causes Chemical Shifts in X-ray Photoelectron Spectroscopy
Nolting, Dirk
Aziz, Emad F.
Ottosson, Niklas
Faubel, Manfred
Hertel, Ingolf V.
Winter, Bernd
We demonstrate the applicability of X-ray photoelectron spectroscopy to obtain charge- and site-specific electronic structural information of biomolecules in aqueous solution. Changing the pH of an aqueous solution of lysine from basic to acidic results in nitrogen 1s and carbon 1s chemical shifts to higher binding energies. These shifts are associated with the sequential protonation of the two amino groups, which affects both charge state and hydrogen bonding to the surrounding water molecules. The N1s chemical shift is 2.2 eV, and for carbon atoms directly neighboring a nitrogen the shift for C1s is ~0.4 eV. The experimental binding energies agree reasonably with our calculated energies of lysine(aq) for different pH values.
2007
Article
http://edoc.mpg.de/340726
info:doi/10.1021/ja072971l
Journal of the American Chemical Society, v.139, 14068-14073 (2007)
en
oai:edoc.mpg.de:3407312008-03-1043:959
Reversible Cell Deformation by a Polymeric Actuator
Pelah, A.
Seemann, R.
Jovin, T. M.
Mechanical forces applied to a living cell affect its development and morphology. The application of different physical forces to a cell provides valuable insights into its rheology, mechanotransduction, and mechanosensing. Here we report on the fabrication and use of polymeric actuators for the reversible deformation of cells. The temperature sensitive polymer poly (N-isopropylacrylamide) was applied in different ways to red blood cells as a model system, demonstrating a wealth of actuating possibilities. Such polymeric actuators may serve as powerful tools in studies of cell biology and biomechanics beause of their ease of preparation and the extensive range of chemical modifications that can be utilized.
2006
Article
http://edoc.mpg.de/340731
info:doi/10.1021/ja067171+
Journal of the American Chemical Society, v.129, 468-469 (2006)
en
oai:edoc.mpg.de:3407342008-03-1543:959
Slow dynamics and glass transition in simulated free-standing polymer films: a possible relation between global and local glass transition temperatures
Peter, S.
Meyer, H.
Baschnagel, J.
Seemann, R.
We employ molecular dynamics simulations to explore the influence that the surface of a free-standing polymer film exerts on its structural relaxation when the film is cooled toward the glass transition. Our simulations are concerned with the features of a coarse-grained bead-spring model in a temperature regime above the critical temperature Tc of mode-coupling theory. We find that the film dynamics is spatially heterogeneous. Monomers at the free surface relax much faster than they would in the bulk at the same temperature T. The fast relaxation of the surface layer continuously turns into bulk-like relaxation with increasing distance y from the surface. This crossover remains smooth for all T, but its range grows on cooling. We show that it is possible to associate a gradient in critical temperatures Tc(y) with the gradient in the relaxation dynamics. This finding is in qualitative agreement with experimental results on supported polystyrene (PS) films (Ellison and Torkelson 2003 Nat. Mater. 2 695). Furthermore we show that the y dependence of Tc(y) can be expressed in terms of the depression of Tc(h)—the global Tc for a film of thickness h—if we assume that Tc(h) is the arithmetic mean of Tc(y) and parameterize the depression of Tc(h) by Tc(h) = Tc/(1+h0/h), a formula suggested by Herminghaus et al (2001 Eur. Phys. J. E 5 531) for the reduction of the glass transition temperature in supported PS films. We demonstrate the validity of this formula by comparing our simulation results to results from other simulations and experiments.
2007
Article
http://edoc.mpg.de/340734
info:doi/10.1088/0953-8984/19/20/205119
Journal of Physics: Condens. Matter, v.19, 205119-1-205119-11 (2007)
en
oai:edoc.mpg.de:3407362008-03-1343:959
Highly Packed and Oriented DNA Mesophases Identified Using in Situ Microfluidic X-ray Microdiffraction
Pfohl, Thomas
Otten, Alexander
Köster, Sarah
Dootz, Rolf
Struth, Bernd
Evans, Heather M.
DNA condensation in vivo usually requires proteins and/or multivalent salts. Here, we explore the in vitro compaction of DNA by cationic dendrimers having an intermediate size and charge. The dynamic assembly of DNA-dendrimer mesophases is discernible due to the laminar flow in a specially designed X-ray compatible microfluidic device. The setup ensures a nonequilibrium ascent of reactant concentration, and the resulting progression of DNA compaction was detected online using microfocused small-angle X-ray diffraction. The evolution of a DNA-dendrimer columnar square mesophase as a function of increasing dendrimer content is described. Additionally, in regions of maximum shear, an unexpected high-level perpendicular ordering of this phase is recorded. Furthermore, these assemblies are found to be in coexistence with a densely packed DNA-only mesophase in regions of excess DNA. The latter is reminiscent of dense packing found in bacteriophage and chromosomes, although surprisingly, it is not stabilized by direct dendrimer contact.
2007
Article
http://edoc.mpg.de/340736
info:doi/10.1021/bm070317s
Biomacromolecules, v.8, 2167-2172 (2007)
en
oai:edoc.mpg.de:3415632008-03-1343:959
Statistical analysis of coherent structures in transitional pipe flow
Schneider, T. M.
Eckhardr, B.
Vollmer, J.
Numerical and experimental studies of transitional pipe flow have shown the prevalence of coherent flow structures that are dominated by downstream vortices. They attract special attention because they contribute predominantly to the increase of the Reynolds stresses in turbulent flow. In the present study we introduce a convenient detector for these coherent states, calculate the fraction of time the structures appear in the flow, and present a Markov model for the transition between the structures. The fraction of states that show vortical structures exceeds 24% for a Reynolds number of about Re=2200, and it decreases to about 20% for Re=2500. The Markov model for the transition between these states is in good agreement with the observed fraction of states, and in reasonable agreement with the prediction for their persistence. It provides insight into dominant qualitative changes of the flow when increasing the Reynolds number.
2007
Article
http://edoc.mpg.de/341563
info:doi/10.1103/PhysRevE.75.066313
Physical Review E, v.75, 066313-1-066313-10 (2007)
en
oai:edoc.mpg.de:3415672008-03-1343:959
Structure Formation in Thin Liquid Films: Interface Forces Unleashed
Seemann, R.
Herminghaus, S.
Jacobs, K.
Springer
2007
Lecture / Courseware
http://edoc.mpg.de/341567
CISM Courses and Lectures, 490, Springer (2007)
en
oai:edoc.mpg.de:3415702008-03-1143:959
Manipulation of Monodisperse Gel Emulsions in Microchannels
Surenjav, E.
Evans, H. M.
Pfohl, T.
Priest, C.
Herminghaus, S.
Seemann, R.
CBM Society
2007
Conference-Paper
http://edoc.mpg.de/341570
urn:ISBN:978-0-9798064-0-7
J.-L. Viovy, P. Tabeling, S. Descroix, L. Malaquin: Proceedings of the µTAS 2007, CBM Society, 339-342 (2007)
en
oai:edoc.mpg.de:3415752008-03-1143:959
Droplet-Based Microfluidics at High Dispersed-Phase Volume Fractions
Priest, C.
Surenjav, E.
Herminghaus, S.
Seemann, R.
CBM Society
2007
Conference-Paper
http://edoc.mpg.de/341575
urn:ISBN:978-0-9798064-0-7
J.-L. Viovy, P. Tabeling, S. Descroix, L. Malaquin: Proceedings of the µTAS 2007, CBM Society, 931 (2007)
en
oai:edoc.mpg.de:3415802008-03-1143:959
Discrete Microfluidics: Production of Silica Particles with Emulsions
Chokkalingam, V.
Priest, C.
Krämer, M.
Maier, W. F.
Herminghaus, S.
Seemann, R.
CBM Society
2007
Conference-Paper
http://edoc.mpg.de/341580
urn:ISBN:978-0-9798064-0-7
J.-L. Viovy, P. Tabeling, S. Descroix, L. Malaquin: Proceedings of the µTAS 2007, CBM Society, 1534 (2007)
en
oai:edoc.mpg.de:3415862008-03-1143:959
Minimal Model for Phase Separation under Slow Cooling
Vollmer, J.
Auernhammer, G. K.
Volmer, D.
Inducing phase separation by a sustained change of temperature often induces repeated waves of nucleation. As demonstrated in an accompanying movie, these oscillations can easily be demonstrated in the classroom by slowly cooling raw spirit (i.e., ethanol) and vegetable oil. In the present communication we suggest a minimal theoretical model predicting that they are of thermodynamic origin. Their frequency depends on the diffusion constant and ramp rate, and is not affected by the overall composition and sample geometry. Our experimental data support this model.
2007
Article
http://edoc.mpg.de/341586
info:doi/10.1103/PhysRevLett.98.115701
Physical Review Letters, v.98, 115701-1-115701-4 (2007)
en
oai:edoc.mpg.de:3415892008-03-1143:959
Hydrogen bonds in liquid water studied by photoelectron spectroscopy
Winter, B.
Aziz, E. F.
Hergenhahn, U.
Faubel, M.
Hertel, I. V.
The authors report on photoelectron emission spectroscopy measurements of the oxygen 1s orbital of liquid water, using a liquid microjet in ultrahigh vacuum. By suitably changing the soft x-ray photon energy, within 600–1200 eV, the electron probing depth can be considerably altered as to either predominantly access the surface or predominantly bulk water molecules. The absolute probing depth in liquid water was inferred from the evolution of the O1s signal and from comparison with aqueous salt solution. The presence of two distinctive components in the core-level photoelectron spectrum, with significantly different binding energies, is revealed. The dominant contribution, at a vertical binding energy of 538.1 eV, was found in bulk and surface sensitive spectra. A weaker component at 536.6 eV binding energy appears to be present only in bulk water. Hartree-Fock calculations of O1s binding energies in different geometric arrangements of the water network are presented to rationalize the experimental distribution of O1s electron binding energies.
2007
Article
http://edoc.mpg.de/341589
info:doi/10.1063/1.2710792
Journal of Chemical Physics, v.136, 124504-1-124504-6 (2007)
en
oai:edoc.mpg.de:3416212008-03-1143:959
Hydrogen bonding in liquid water probed by resonant Auger-electron spectroscopy
Winter, B.
Hergenhahn, U.
Faubel, M.
Björneholm, O.
Hertel, I. V.
We have measured resonant and off-resonant Auger-electron spectra of liquid water. Continuumlike transitions near and above the O1s vertical ionization energy are identified by the characteristic normal Auger-electron spectra. On the contrary, well-resolved spectator shifts of the main Auger-electron peak are observed at the liquid-water O1s absorption main edge and near the absorption pre-edge. The shifts of 1.4 and 1.9 eV arise from the localized nature of the excitation. Excited-state localization/delocalization is also discussed for the analogous vacuum ultraviolet (VUV) transitions, and we point out the similarities between x-ray and VUV absorption spectra of liquid water.
2007
Article
http://edoc.mpg.de/341621
Journal of Chemical Physics, v.127, 094501-1-094501-6 (2007)
en
oai:edoc.mpg.de:3416312008-03-1143:959
Surface Hydrophobicity Causes SO₂ Tolerance in Lichens
Hauck, M.
Jürgens, S.-R.
Brinkmann, M.
Herminghaus, S.
Background and Aims: The superhydrophobicity of the thallus surface in one of the most SO2-tolerant lichen species, Lecanora conizaeoides, suggests that surface hydrophobicity could be a general feature of lichen symbioses controlling their tolerance to SO2. The study described here tests this hypothesis.
Methods: Water droplets of the size of a raindrop were placed on the surface of air-dry thalli in 50 lichen species of known SO2 tolerance and contact angles were measured to quantify hydrophobicity.
Key Results: The wettability of lichen thalli ranges from strongly hydrophobic to strongly hydrophilic. SO2 tolerance of the studied lichen species increased with increasing hydrophobicity of the thallus surface. Extraction of extracellular lichen secondary metabolites with acetone reduced, but did not abolish the hydrophobicity of lichen thalli.
Conclusions: Surface hydrophobicity is the main factor controlling SO2 tolerance in lichens. It presumably originally evolved as an adaptation to wet habitats preventing the depression of net photosynthesis due to supersaturation of the thallus with water. Hydrophilicity of lichen thalli is an adaptation to dry or humid, but not directly rain-exposed habitats. The crucial role of surface hydrophobicity in SO2 also explains why many markedly SO2-tolerant species are additionally tolerant to other (chemically unrelated) toxic substances including heavy metals.
2007
Article
http://edoc.mpg.de/341631
info:doi/10.1093/aob/mcm306
Annals of Botany, v.101, 531-539 (2007)
en
oai:edoc.mpg.de:3416342008-03-1343:959
Morphological Clues to Wet Granular Pile Stability
Scheel, M.
Seemann, R.
Brinkmann, M.
Di Michiel, M.
Sheppard, A.
Breidenbach, B.
Herminghaus, S.
When a granular material such as sand is mixed with a certain amount of liquid, the surface tension of the latter bestows considerable stiffness to the material, which enables, for example, sand castles to be sculpted. The geometry of the liquid interface within the granular pile is of extraordinary complexity and strongly varies with the liquid content. Surprisingly, the mechanical properties of the pile are largely independent of the amount of liquid over a wide range. We resolve this puzzle with the help of X-ray microtomography, showing that the remarkable insensitivity of the mechanical properties to the liquid content is due to the particular organization of the liquid in the pile into open structures. For spherical grains, a simple geometric rule is established, which relates the macroscopic properties to the internal liquid morphologies. We present evidence that this concept is also valid for systems with non-spherical grains. Hence, our results provide new insight towards understanding the complex physics of a large variety of wet granular systems including land slides, as well as mixing and agglomeration problems.
2008
Article
http://edoc.mpg.de/341634
info:doi/10.1038/nmat2117
Nature Materials, v.7, 189-193 (2008)
en
oai:edoc.mpg.de:3416452008-03-1143:959
Preparation and characterization of water in oil emulsion via drop break-off
Ulmeanu, M.
Water in oil emulsion with drop sizes ranging from 15 to 400 m was produced via drop break-off in a co-flowing environment. A phase diagram illustrating the drop break-up formation mechanism and size distribution as a function of disperse and continuous phase flow rate is presented. The
drop break-up dynamic dominated by the disperse flow rate gives the transition point between monodisperse and polydisperse emulsion production. In addition, we studied the formation of 2D and 3D emulsion crystalline structures by mixing droplets with two distinct diameters with a certain size ratio, which may lead to a novel type of chemical reaction setup and new materials.
2007
Article
http://edoc.mpg.de/341645
info:doi/10.1016/j.colsurfa.2007.08.038
Colloids and Surfaces A, v.316, 119-125 (2007)
en
oai:edoc.mpg.de:3416512008-03-1143:959
An In Situ Study of Collagen Self-Assembly Processes
Köster, S.
Evans, H. M.
Wong, J. Y.
Pfohl, T.
We present in situ studies on the self-assembly and dynamic evolution of collagen gels from semidilute solutions in a microfluidic device. Collagen fibrils not only reinforce the mechanical properties of bone and tissues, but they also influence cellular motility and morphology. We access the initial steps of the hierarchical self-assembly of collagen fibrils and networks by using hydrodynamic focusing to form oriented fibers. The accurate description of the conditions within the microchannel requires a numerical expression for the pH in the device as well as a modified mathematical description of the viscosity, which increases nearly 300-fold as collagen fibrils form around neutral pH. Finite element modeling profiles overlay impressively with cross-polarized microscopy images of the birefringent fibrils in the channel. Real-time X-ray microdiffraction measurements in flow indicate an enhanced supramolecular packing having a unit spacing commensurate with that of a pentameric collagen subunit. These results have significant implications for the field of biomedicine, wherein new aligned, cellularly active, and mechanically strengthened materials continue to be in demand. However, this work is also remarkable from a more fundamental, biophysical point of view because the underlying concepts may be generalized to a large pool of systems.
2007
Article
http://edoc.mpg.de/341651
info:doi/10.1021/bm700973t
Biomacromolecules, v.9, 199-207 (2007)
en
oai:edoc.mpg.de:3416562008-03-1143:959
Contact line stability of ridges and drops
Mechkov, S.
Oshanin, G.
Rauscher, M.
Brinkmann, M.
Cazabat, A. M.
Dietrich, S.
2007
Article
http://edoc.mpg.de/341656
info:doi/10.1209/0295-5075/80/66002
Europhysics Letters, v.80, 66002-1-66002-6 (2007)
en
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