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334 results on '"Ferber C"'

102. Phase separation in star-polymer–colloid mixtures

Author

Dzubiella, J., primary, Jusufi, A., additional, Likos, C. N., additional, von Ferber, C., additional, Löwen, H., additional, Stellbrink, J., additional, Allgaier, J., additional, Richter, D., additional, Schofield, A. B., additional, Smith, P. A., additional, Poon, W. C. K., additional, and Pusey, P. N., additional

Published
2001
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104. Phase transitions in soft matter systems.

Author

Lo¨wen, H., Watzlawek, M., Likos, C. N., Schmidt, M., Jusufi, A., Graf, H., Denton, A. R., and von Ferber, C.

Subjects
MATTER, PHASE transitions, COLLOIDS
Abstract

We review recent work on fluid-solid and solid-solid phase transitions in soft matter systems such as colloidal suspensions and star polymer solutions. Starting from a given interparticle pair potential we predict the corresponding phase diagrams using computer simulations, cell theory, and density functional theory. When possible, the results are compared with experimental data. In particular, we discuss the following aspects: a cascade of freezing transitions for confined colloids, stable one-component quasicrystals for charged colloids, reentrant melting and anisotropic solid phases for star polymer solutions and reentrant nematic ordering for suspensions of the tobacco-mosaic virus. [ABSTRACT FROM AUTHOR]

Published
2000

105. The hard physics of soft matter.

Author

Kramer, Bernhard, Löwen, H., Watzlawek, M., Likos, C. N., Schmidt, M., Jusufi, A., Dzubiella, J., von Ferber, C., Allahyarov, E., Thünemann, A., and D'Amico, I.

Abstract

By definition, soft matter systems react sensitively upon external mechanical perturbations. This material class includes mesoscopic complex fluids such as colloids, polymers and membranes. It is a major challenge to understand the fascinating properties of soft matter from first principles, i.e., by deriving its properties from the microscopic interactions. Here, concepts borrowed from statistical physics are described, which are capable to overbridge the gap from microscopic over mesoscopic to macroscopic length scales. This is illustrated explicitly for star polymer solutions and charged colloidal suspensions. [ABSTRACT FROM AUTHOR]

Published
2000
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123. Scaling behaviour of lattice animals at the upper critical dimension.

Author

Ferber, C., Foster, D., Hsu, H., and Kenna, R.

Subjects
*LATTICE theory, *COMPUTER simulation, *MONTE Carlo method, *SCALING laws (Statistical physics), *LOGARITHMIC functions, *PREDICTION theory, *HYPERCUBES
Abstract

We perform numerical simulations of the lattice-animal problem at the upper critical dimension d = 8 on hypercubic lattices in order to investigate logarithmic corrections to scaling there. Our stochastic sampling method is based on the pruned-enriched Rosenbluth method (PERM), appropriate to linear polymers, and yields high statistics with animals comprised of up to 8000 sites. We estimate both the partition sums (number of different animals) and the radii of gyration. We re-verify the Parisi-Sourlas prediction for the leading exponents and compare the logarithmic-correction exponents to two partially differing sets of predictions from the literature. Finally, we propose, and test, a new Parisi-Sourlas-type scaling relation appropriate for the logarithmic-correction exponents. [ABSTRACT FROM AUTHOR]

Published
2011
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125. DNA THERMAL DENATURATION VIEWED AS A PHASE TRANSITION: SCALING LAWS AND BEYOND.

Author

Honchar, Yu., von Ferber, C., and Holovatch, Yu.

Subjects
*DNA denaturation, *PHASE transitions, *QUANTUM gravity, *DNA, *EXPONENTS
Abstract

We consider the Poland-Scheraga model of DNA thermal denaturation, where the unzipping of DNA double chain is viewed as a phase transition [1]. We apply polymer field theory to conform that this sort of transition is in fact a first-order one. The order of phase transition is governed by the loop exponent c, which may be calculated from other polymer entropy exponents. We show that DNA chain heterogeneity increases the strength of the first order transition. For dimensionality d = 3 the exponents were obtained from ε = 4 − d expansions up to the fourth order, and also for d = 2 in the case of the so-called quantum gravity the solution is exact. Additionally, presence of obstacles in the space around the molecule (crowded environment) further reinforces the first-order transition. [ABSTRACT FROM AUTHOR]

Published
2022
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126. Polymer stars in three dimensions. Three-loop results.

Author

Ferber, C. and Holovatch, Yu.

Abstract

We study the scaling properties of self-avoiding polymer stars and networks of arbitrarily given but fixed topologies. We use the massive field theory renormalization group framework to calculate the critical exponents governing the universal properties (star exponents). Calculations are performed directly in three dimensions; renormalization group functions are obtained in the three-loop approximation. Resulting asymptotic series for the star exponents are resummed with the help of the Padé-Borel and conformal mapping transformations. [ABSTRACT FROM AUTHOR]

Published
1996
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128. Generalized Vicsek Fractals:  Regular Hyperbranched Polymers

Author

Blumen, A., Ferber, C. von, Jurjiu, A., and Koslowski, T.

Abstract

We focus on Vicsek fractals (VF), which are regular hyperbranched macromolecules. As such, they belong to the same family as the dendrimers, without suffering from the growth problems of the latter. We compute the mechanical and dielectric properties of VF in dilute solutions. The evaluation of the static and dynamical properties of VF in the framework of generalized Gaussian structures (GGS) reveals that they, distinct from the dendrimers, obey scaling. Theoretically speaking, VF are probably the most natural extension of GGS from linear chains to nontrivial loopless fractal objects. We encourage the synthesis and experimental characterization of the properties of this class of hyperbranched macromolecules.

Published
2004

130. Colloids with polymer stars: the interaction

Author

Ferber, C. von, Holovatch, Yu., Jusufi, A., Likos, C.N., Lo¨wen, H., and Watzlawek, M.

Abstract

We derive the short distance interaction of star polymers in a colloidal solution. We calculate the corresponding force between two stars with arbitrary numbers of legs f 1 and f 2 . We show that a simple scaling theory originally derived for high f 1 , f 2 nicely matches with the results of elaborated renormalization group analysis for f 1 + f 2 ≤ 6 generalizing and confirming a previous conjecture based only on scaling results for f 1 = f 2 = 1, 2.

Published
2001
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132. Immobilization of Retinoic Acid by Polyamino Acids:  Lamellar-Structured Nanoparticles

Author

Thunemann, A. F., Beyermann, J., Ferber, C. von, and Lowen, H.

Abstract

We discuss the preparation, the X-ray spectra and their theory, and electron microscopy of nanoparticles showing a lamellar internal structure. Retinoic acid was immobilized by complexation with poly(l-arginine), poly(l-histidine), and poly(l-lysine). The resulting solid-state complexes were prepared as nanoparticles with diameters of 320−380 nm, and with internal structures, which are smectic A-like. By small-angle X-ray scattering the unit cell was determined to be in the range of 3.10−3.62 nm, thus depending linearly on the monomer mass. The X-ray scattering of finite lamellar structures of “onion”- and “tart”-type spherical nanoparticles were determined theoretically. The uniform boundary of the onion-type particles results in secondary maxima near the Bragg reflections. Further, the highest degree of polydispersity to find these secondary maxima in scattering experiments was determined to be about 1% if the particle size is 300 nm. When electron microscopy was used, it was shown that the particles consist of a complex-containing core surrounded by a dispersing agent-containing shell. The core was revealed to be more of the tart- than the onion-type. When circular dichroism was used, the conformation of poly(l-arginine) and poly(l-lysine) within the complexes was determined to be an α-helix, whereas that of poly(l-histidine) was predominantly of the coil-type.

Published
2000

136. Calculating deuteron photodisintegration amplitudes using nonsingular scattering equations

Author

Sandhas W, von Ferber C, and Haberzettl H

Subjects
Physics, Nuclear and High Energy Physics, Differential equation, Nuclear Theory, Integral equation, Schrödinger equation, Lippmann–Schwinger equation, symbols.namesake, Matrix (mathematics), Photodisintegration, Quantum electrodynamics, symbols, Wave function, S-matrix
Abstract

We derive a momentum-space formulation of the deuteron photodisintegration in terms of nonsingular scattering integral equations. The two-body {ital T} matrix describing the nuclear final-state interactions enters only on shell, thus offering the possibility of determining it entirely in terms of experimental phase shifts. The formalism suggests a lowest-order approximation which goes beyond the usual plane-wave approximation and which contains the full information of the on-shell final-state interaction. Test calculations using the Reid soft-core potential are reported. It is found that the numerical solution of photodisintegration observables is greatly facilitated by the proposed formalism. Moreover, the lowest-order approximation is seen to be superior to the usual plane-wave approximation, providing good results even in those cases where the usual plane-wave approximation vanishes. Extensions to more complex few-nucleon systems are discussed.

Published
1989

138. Complex networks

Author

Yurij Holovatch, Olemskoi, O., Ferber, C., Holovatch, T., Mryglod, O., Olemskoi, I., and Palchykov, V.

Subjects
General Physics and Astronomy

141. Platelet function in patients with advanced malignancies treated with subcutaneous recombinant human interleukin-1 beta (IL-1 beta)

Author

Matic G.B., Ferber, C., Steinbrenner, A., Mertelsmann, R., Holidack, J., Bruquer, W., and Kanz, L.

Subjects
Blood platelets -- Activation, Interleukin-1 -- Health aspects, Business, Health care industry
Abstract

According to an abstract submitted by the authors to the 36th Annual Meeting of the American Society of Hematology, held December 2-6, 1994, in Nashville, Tennessee, 'IL-1(beta) displays a prothrombotic [...]

Published
1995

146. Platelet function after combination chemotherapy and treatment with recombinant human granulocyte-colony-stimulating factor (rhG-CSF)

Author

Matic, G.B., Ferber, C., Steinbrenner, A., Brugger, W., and Kanz, L.

Subjects
Blood platelets -- Activation, Chemotherapy, Combination -- Research, Granulocyte colony-stimulating factor -- Health aspects, Business, Health care industry
Abstract

According to an abstract submitted by the authors to the 36th Annual Meeting of the American Society of Hematology, held December 2-6, 1994, in Nashville, Tennessee, 'Receptors for granulocyte-colony-stimulating factor [...]

Published
1995

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