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2020


Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles
Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles

Singh, D., Domínguez, A., Choudhury, U., Kottapalli, S., Popescu, M., Dietrich, S., Fischer, P.

Nature Communications, 11(2210), May 2020 (article)

Abstract
Symmetry breaking and the emergence of self-organized patterns is the hallmark of com- plexity. Here, we demonstrate that a sessile drop, containing titania powder particles with negligible self-propulsion, exhibits a transition to collective motion leading to self-organized flow patterns. This phenomenology emerges through a novel mechanism involving the interplay between the chemical activity of the photocatalytic particles, which induces Mar- angoni stresses at the liquid–liquid interface, and the geometrical confinement provided by the drop. The response of the interface to the chemical activity of the particles is the source of a significantly amplified hydrodynamic flow within the drop, which moves the particles. Furthermore, in ensembles of such active drops long-ranged ordering of the flow patterns within the drops is observed. We show that the ordering is dictated by a chemical com- munication between drops, i.e., an alignment of the flow patterns is induced by the gradients of the chemicals emanating from the active particles, rather than by hydrodynamic interactions.

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link (url) DOI [BibTex]


Spectrally selective and highly-sensitive UV photodetection with UV-A, C band specific polarity switching in silver plasmonic nanoparticle enhanced gallium oxide thin-film
Spectrally selective and highly-sensitive UV photodetection with UV-A, C band specific polarity switching in silver plasmonic nanoparticle enhanced gallium oxide thin-film

Arora, K., Singh, D., Fischer, P., Kumar, M.

Adv. Opt. Mat., March 2020 (article)

Abstract
Traditional photodetectors generally show a unipolar photocurrent response when illuminated with light of wavelength equal or shorter than the optical bandgap. Here, we report that a thin film of gallium oxide (GO) decorated with plasmonic nanoparticles, surprisingly, exhibits a change in the polarity of the photocurrent for different UV bands. Silver (Ag) nanoparticles are vacuum-deposited onto β-Ga2O3 and the AgNP@GO thin films show a record responsivity of 250 A/W, which significantly outperforms bare GO planar photodetectors. The photoresponsivity reverses sign from +157 µA/W in the UV-C band under unbiased operation to -353 µA/W in the UV-A band. The current reversal is rationalized by considering the charge dynamics stemming from hot electrons generated when the incident light excites a local surface plasmon resonance (LSPR) in the Ag nanoparticles. The Ag nanoparticles improve the external quantum efficiency and detectivity by nearly one order of magnitude with high values of 1.2×105 and 3.4×1014 Jones, respectively. This plasmon-enhanced solar blind GO detector allows UV regions to be spectrally distinguished, which is useful for the development of sensitive dynamic imaging photodetectors.

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[BibTex]


Investigating photoresponsivity of graphene-silver hybrid nanomaterials in the ultraviolet
Investigating photoresponsivity of graphene-silver hybrid nanomaterials in the ultraviolet

Deshpande, P., Suri, P., Jeong, H., Fischer, P., Ghosh, A., Ghosh, G.

J. Chem. Phys., 152, pages: 044709, January 2020 (article)

Abstract
There have been several reports of plasmonically enhanced graphene photodetectors in the visible and the near infrared regime but rarely in the ultraviolet. In a previous work, we have reported that a graphene-silver hybrid structure shows a high photoresponsivity of 13 A/W at 270 nm. Here, we consider the likely mechanisms that underlie this strong photoresponse. We investigate the role of the plasmonic layer and examine the response using silver and gold nanoparticles of similar dimensions and spatial arrangement. The effect on local doping, strain, and absorption properties of the hybrid is also probed by photocurrent measurements and Raman and UV-visible spectroscopy. We find that the local doping from the silver nanoparticles is stronger than that from gold and correlates with a measured photosensitivity that is larger in devices with a higher contact area between the plasmonic nanomaterials and the graphene layer.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


A High-Fidelity Phantom for the Simulation and Quantitative Evaluation of Transurethral Resection of the Prostate
A High-Fidelity Phantom for the Simulation and Quantitative Evaluation of Transurethral Resection of the Prostate

Choi, E., Adams, F., Gengenbacher, A., Schlager, D., Palagi, S., Müller, P., Wetterauer, U., Miernik, A., Fischer, P., Qiu, T.

Annals of Biomed. Eng., 48, pages: 437-446, January 2020 (article)

Abstract
Transurethral resection of the prostate (TURP) is a minimally invasive endoscopic procedure that requires experience and skill of the surgeon. To permit surgical training under realistic conditions we report a novel phantom of the human prostate that can be resected with TURP. The phantom mirrors the anatomy and haptic properties of the gland and permits quantitative evaluation of important surgical performance indicators. Mixtures of soft materials are engineered to mimic the physical properties of the human tissue, including the mechanical strength, the electrical and thermal conductivity, and the appearance under an endoscope. Electrocautery resection of the phantom closely resembles the procedure on human tissue. Ultrasound contrast agent was applied to the central zone, which was not detectable by the surgeon during the surgery but showed high contrast when imaged after the surgery, to serve as a label for the quantitative evaluation of the surgery. Quantitative criteria for performance assessment are established and evaluated by automated image analysis. We present the workflow of a surgical simulation on a prostate phantom followed by quantitative evaluation of the surgical performance. Surgery on the phantom is useful for medical training, and enables the development and testing of endoscopic and minimally invasive surgical instruments.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


Interactive Materials – Drivers of Future Robotic Systems
Interactive Materials – Drivers of Future Robotic Systems

Fischer, P.

Adv. Mat., January 2020 (article)

Abstract
A robot senses its environment, processes the sensory information, acts in response to these inputs, and possibly communicates with the outside world. Robots generally achieve these tasks with electronics-based hardware or by receiving inputs from some external hardware. In contrast, simple microorganisms can autonomously perceive, act, and communicate via purely physicochemical processes in soft material systems. A key property of biological systems is that they are built from energy-consuming ‘active’ units. Exciting developments in material science show that even very simple artificial active building blocks can show surprisingly rich emergent behaviors. Active non-equilibrium systems are therefore predicted to play an essential role to realize interactive materials. A major challenge is to find robust ways to couple and integrate the energy-consuming building blocks to the mechanical structure of the material. However, success in this endeavor will lead to a new generation of sophisticated micro- and soft-robotic systems that can operate autonomously.

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link (url) DOI [BibTex]


Self-supervised motion deblurring
Self-supervised motion deblurring

Liu, P., Janai, J., Pollefeys, M., Sattler, T., Geiger, A.

IEEE Robotics and Automation Letters, 2020 (article)

Abstract
Motion blurry images challenge many computer vision algorithms, e.g., feature detection, motion estimation, or object recognition. Deep convolutional neural networks are state-of-the-art for image deblurring. However, obtaining training data with corresponding sharp and blurry image pairs can be difficult. In this paper, we present a differentiable reblur model for self-supervised motion deblurring, which enables the network to learn from real-world blurry image sequences without relying on sharp images for supervision. Our key insight is that motion cues obtained from consecutive images yield sufficient information to inform the deblurring task. We therefore formulate deblurring as an inverse rendering problem, taking into account the physical image formation process: we first predict two deblurred images from which we estimate the corresponding optical flow. Using these predictions, we re-render the blurred images and minimize the difference with respect to the original blurry inputs. We use both synthetic and real dataset for experimental evaluations. Our experiments demonstrate that self-supervised single image deblurring is really feasible and leads to visually compelling results.

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pdf Project Page Blog [BibTex]

pdf Project Page Blog [BibTex]


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Wetting transitions on soft substrates

Napiorkowski, M., Schimmele, L., Dietrich, S.

{EPL}, 129(1), EDP Science, Les-Ulis, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Blessing and Curse: How a Supercapacitor Large Capacitance Causes its Slow Charging

Lian, C., Janssen, M., Liu, H., van Roij, R.

Physical Review Letters, 124(7), American Physical Society, Woodbury, N.Y., 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Fractal-seaweeds type functionalization of graphene

Amsharov, K., Sharapa, D. I., Vasilyev, O. A., Martin, O., Hauke, F., Görling, A., Soni, H., Hirsch, A.

Carbon, 158, pages: 435-448, Elsevier, Amsterdam, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Energy storage in steady states under cyclic local energy input

Zhang, Y., Holyst, R., Maciolek, A.

Physical Review E, 101(1), American Physical Society, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]

2007


Frequency-domain displacement sensing with a fiber ring-resonator containing a variable gap
Frequency-domain displacement sensing with a fiber ring-resonator containing a variable gap

Vollmer, F., Fischer, P.

SENSORS AND ACTUATORS A-PHYSICAL, 134(2):410-413, 2007 (article)

Abstract
Ring-resonators are in general not amenable to strain-free (non-contact) displacement measurements. We show that this limitation may be overcome if the ring-resonator, here a fiber-loop, is designed to contain a gap, such that the light traverses a free-space part between two aligned waveguide ends. Displacements are determined with nanometer sensitivity by measuring the associated changes in the resonance frequencies. Miniaturization should increase the sensitivity of the ring-resonator interferometer. Ring geometries that contain an optical circulator can be used to profile reflective samples. (c) 2006 Elsevier B.V. All rights reserved.

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DOI [BibTex]

2007


DOI [BibTex]


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Monte Carlo simulation results for critical Casimir forces

Vasilyev, O., Gambassi, A., Maciolek, A., Dietrich, S.

EPL, 80, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir effect in superfluid wetting films

Maciolek, A., Gambassi, A., Dietrich, S.

Physical Review E, 76, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Complete wetting of pits and grooves

Tasinkevych, M., Dietrich, S.

European Physical Journal e: Soft Matter, 23(1):117-128, 2007 (article)

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[BibTex]

[BibTex]


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Experimental observation of structural crossover in binary mixtures of colloidal hard spheres

Baumgartl, J., Dullens, R. P. A., Dijkstra, M., Roth, R., Bechinger, C.

Physical Review Letters, 98, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Physical basis for characterizing native structures of proteins

Harano, Y., Roth, R., Sugita, Y., Ikeguchi, M., Kinoshita, M.

Chemical Physics Letters, 437(1 - 3):112-116, 2007 (article)

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[BibTex]

[BibTex]


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Importance of boundary conditions for fluctuation-induced forces between colloids at interfaces

Lehle, H., Oettel, M.

Physical Review E, 75(1), 2007 (article)

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[BibTex]

[BibTex]


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Colloid-colloid and colloid-wall interactions in driven suspensions

Krüger, M., Rauscher, M.

The Journal of Chemical Physics, 127(3), 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Solvation of proteins: linking thermodynamics to geometry

Hansen-Goos, H., Roth, R., Mecke, K., Dietrich, S.

Physical Review Letters, 99, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Thermal noise influences fluid flow in thin films during spinodal dewetting

Fetzer, R., Rauscher, M., Seemann, R., Jacobs, K., Mecke, K.

Physical Review Letters, 99(11), 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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On the distribution of surface extrema in several one- and two-dimensional random landscapes

Hivert, F., Nechaev, S., Oshanin, G.

Journal of Statistical Physics, 126(2):243-279, 2007 (article)

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[BibTex]

[BibTex]


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Intermittent random walks for an optimal search strategy: one-dimensional case

Oshanin, G., Wio, H. S., Lindenberg, K., Burlatsky, S. F.

Journal of Physics: Condensed Matter, 19(6), 2007 (article)

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[BibTex]

[BibTex]


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Effective free-energy method for nematic liquid crystals in contact with structured substrates

Harnau, L., Kondrat, S., Poniewierski, A.

Physical Review E, 76, 2007 (article)

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[BibTex]

[BibTex]


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Structure factor and thermodynamics of rigid dendrimers in solution

Harnau, L., Rosenfeldt, S., Ballauff, M.

The Journal of Chemical Physics, 127, 2007 (article)

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[BibTex]

[BibTex]


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Fluctuation spectra of free and supported membrane pairs

Merath, R.-J., Seifert, U.

European Physical Journal e - Soft Matter, 23(1):103-116, 2007 (article)

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[BibTex]

[BibTex]


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Conceptual aspects of line tensions

Schimmele, L., Napiorkowski, M., Dietrich, S.

The Journal of Chemical Physics, 127(16), 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Ageing in the contact process: scaling behaviour and universal features

Baumann, F., Gambassi, A.

Journal of Statistical Mechanics: Theory and Experiment, 2007, Institute of Physics Publishing, Bristol, England, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Charge renormalization for effective interactions of colloids at water interfaces

Frydel, D., Dietrich, S., Oettel, M.

Physical Review Letters, 99, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Multiphase coexistence in polydisperse colloidal mixtures

Grodon, C., Roth, R.

The Journal of Chemical Physics, 126(5), 2007 (article)

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[BibTex]

[BibTex]


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Softening of the stiffness of bottle-brush polymers by mutual interaction

Bolisetty, S., Ariaud, C., Xu, Y., Müller, A. H. E., Harnau, L., Rosenfeldt, S., Lindner, P., Ballauff, M.

Physical Review E, 75, 2007 (article)

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[BibTex]

[BibTex]


Observation of the Faraday effect via beam deflection in a longitudinal magnetic field
Observation of the Faraday effect via beam deflection in a longitudinal magnetic field

Ghosh, A., Hill, W., Fischer, P.

PHYSICAL REVIEW A, 76(5), 2007 (article)

Abstract
We show that magnetic-field-induced circular differential deflection of light can be observed in reflection or refraction at a single interface. The difference in the reflection or refraction angles between the two circular polarization components is a function of the magnetic-field strength and the Verdet constant, and permits the observation of the Faraday effect not via polarization rotation in transmission, but via changes in the propagation direction. Deflection measurements do not suffer from n-pi ambiguities and are shown to be another means to map magnetic fields with high axial resolution, or to determine the sign and magnitude of magnetic-field pulses in a single measurement.

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DOI [BibTex]


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Spreading in narrow channels

Dotti, C., Gambassi, A., Popescu, M. N., Dietrich, S.

Physical Review E, 76, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Binary reactive adsorbate on a random catalytic substrate

Popescu, M. N., Dietrich, S., Oshanin, G.

Journal of Physics: Condensed Matter, 19(6), 2007 (article)

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[BibTex]

[BibTex]


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Theory of capillary-induced interactions beyond the superposition approximation

Dominguez, A., Oettel, M., Dietrich, S.

The Journal of Chemical Physics, 127, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Shear flow pumping in open micro- and nanofluidic systems

Rauscher, M., Dietrich, S., Koplik, J.

Physical Review Letters, 98, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Effective forces induced by a fluctuating interface: exact results

Abraham, D., Essler, F., Maciolek, A.

Physical Review Letters, 98(17), 2007 (article)

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[BibTex]

[BibTex]


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Inner structure of thin films of lamellar poly(styrene-b-butadiene) diblock copolymers as revealed by grazing-incidence small-angle scattering

Busch, P., Posselt, D., Smilgies, D.-M., Rauscher, M., Papadakis, C. M.

Macromolecules, 40(3):630-640, 2007 (article)

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[BibTex]

[BibTex]


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Quantifying hydrodynamic slip: a comprehensive analysis of dewetting profiles

Fetzer, R., Münch, A., Wagner, B., Rauscher, M., Jacobs, K.

Langmuir, 23(21):10559-10566, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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A dynamic density functional theory for particles in a flowing solvent

Rauscher, M., Dom\’\inguez, A., Krüger, M., Penna, F.

The Journal of Chemical Physics, 127(24), 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Slow dynamics in critical ferromagnetic vector models relaxing from a magnetized initial state

Calabrese, P., Gambassi, A.

Journal of Statistical Mechanics: Theory and Experiment, Jan 2007, 2007 (article)

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[BibTex]

[BibTex]


Circular differential double diffraction in chiral media
Circular differential double diffraction in chiral media

Ghosh, A., Fazal, F. M., Fischer, P.

OPTICS LETTERS, 32(13):1836-1838, 2007 (article)

Abstract
In an optically active liquid the diffraction angle depends on the circular polarization state of the incident light beam. We report the observation of circular differential diffraction in an isotropic chiral medium, and we demonstrate that double diffraction is an alternate means to determine the handedness (enantiomeric excess) of a solution. (c) 2007 Optical Society of America.

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DOI [BibTex]

DOI [BibTex]


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Contact line stability of ridges and drops

Mechkov, S., Oshanin, G., Rauscher, M., Brinkmann, M., Cazabat, A. M., Dietrich, S.

Europhysics Letters, 80(6), 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Interplay of critical Casimir and dispersion forces

Dantchev, D., Schlesener, F., Dietrich, S.

Physical Review E, 76, 2007 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical adsorption on nonspherical colloidal particles

Kondrat, S., Harnau, L., Dietrich, S.

The Journal of Chemical Physics, 126, 2007 (article)

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[BibTex]

[BibTex]


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Random patterns generated by random permutations of natural numbers

Oshanin, G., Voituriez, R., Nechaev, S., Vasilyev, O., Hivert, F.

European Physical Journal - Special Topics, 143, pages: 143-157, 2007 (article)

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[BibTex]

[BibTex]


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Single lamella nanoparticles of polyethylene

Weber, C. H. M., Chiche, A., Krausch, G., Rosenfeldt, S., Ballauff, M., Harnau, L., Goettker-Schnetmann, I., Tong, Q., Mecking, S.

Nano Letters, 7, pages: 2024-2029, 2007 (article)

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[BibTex]

[BibTex]