Search results for " Soft"

Stimuli-responsive brushes with active minority components: Monte Carlo study and analytical theory

2015

Using a combination of analytical theory, Monte Carlo simulations, and three dimensional self-consistent field calculations, we study the equilibrium properties and the switching behavior of adsorption-active polymer chains included in a homopolymer brush. The switching transition is driven by a conformational change of a small fraction of minority chains, which are attracted by the substrate. Depending on the strength of the attractive interaction, the minority chains assume one of two states: An exposed state characterized by a stem-crown-like conformation, and an adsorbed state characterized by a flat two-dimensional structure. Comparing the Monte Carlo simulations, which use an Edwards-…

Anomalous Structure and Scaling of Ring Polymer Brushes

2011

A comparative simulation study of polymer brushes formed by grafting at a planar surface either flexible linear polymers (chain length $N_L$) or (non-catenated) ring polymers (chain length $N_R=2 N_L$) is presented. Two distinct off-lattice models are studied, one by Monte Carlo methods, the other by Molecular Dynamics, using a fast implementation on graphics processing units (GPUs). It is shown that the monomer density profiles $\rho(z)$ in the $z$-direction perpendicular to the surface for rings and linear chains are practically identical, $\rho_R(2 N_L, z)=\rho_L(N_L, z)$. The same applies to the pressure, exerted on a piston at hight z, as well. While the gyration radii components of ri…

Structure of bottle-brush polymers in solution: A Monte Carlo test of models for the scattering function

2008

Extensive Monte Carlo results are presented for a lattice model of a bottle-brush polymer under good solvent or Theta solvent conditions. Varying the side chain length, backbone length, and the grafting density for a rigid straight backbone, both radial density profiles of monomers and side chain ends are obtained, as well as structure factors describing the scattering from a single side chain and from the total bottle-brush polymer. To describe the structure in the interior of a very long bottle-brush, a periodic boundary condition in the direction along the backbone is used, and to describe effects due to the finiteness of the backbone length, a second set of simulations with free ends of…

A fast Monte Carlo algorithm for studying bottle-brush polymers

2011

Obtaining reliable estimates of the statistical properties of complex macromolecules by computer simulation is a task that requires high computational effort as well as the development of highly efficient simulation algorithms. We present here an algorithm combining local moves, the pivot algorithm, and an adjustable simulation lattice box for simulating dilute systems of bottle-brush polymers with a flexible backbone and flexible side chains under good solvent conditions. Applying this algorithm to the bond fluctuation model, very precise estimates of the mean square end-to-end distances and gyration radii of the backbone and side chains are obtained, and the conformational properties of s…

Conformational studies of bottle-brush polymers absorbed on a flat solid surface.

2010

The adsorption of a bottle-brush polymer end-grafted with one chain end of its backbone to a flat substrate surface is studied by Monte Carlo simulation of a coarse-grained model, that previously has been characterized in the bulk, assuming a dilute solution under good solvent conditions. Applying the bond fluctuation model on the simple cubic lattice, we vary the backbone chain length $N_b$ from $N_b=67$ to $N_b = 259$ effective monomeric units, the side chain length $N$ from N=6 to N=48, and the grafting density $\sigma=1$, i.e., parameters that correspond well to the experimentally accessible range. When the adsorption energy strength $\epsilon$ is varied, we find that the adsorption tra…

Theory and Simulation of Multiphase Polymer Systems

2010

The theory of multiphase polymer systems has a venerable tradition. The 'classical' theory of polymer demixing, the Flory-Huggins theory, was developed already in the forties of the last century. It is still the starting point for most current approaches -- be they improved theories for polymer (im)miscibility that take into account the microscopic structure of blends more accurately, or sophisticated field theories that allow to study inhomogeneous multicomponent systems of polymers with arbitrary architectures in arbitrary geometries. In contrast, simulations of multiphase polymer systems are relatively young. They are still limited by the fact that one must simulate a large number of lar…

Una questione di software

2012

A gearbox model for processing large volumes of data by using pipeline systems encapsulated into virtual containers

2020

Software pipelines enable organizations to chain applications for adding value to contents (e.g., confidentially, reliability, and integrity) before either sharing them with partners or sending them to the cloud. However, the pipeline components add overhead when processing large volumes of data, which can become critical in real-world scenarios. This paper presents a gearbox model for processing large volumes of data by using pipeline systems encapsulated into virtual containers. In this model, the gears represent applications, whereas gearboxes represent software pipelines. This model was implemented as a collaborative system that automatically performs Gear up (by using parallel patterns…

Coesione europea e strategie di soft planning: tracce di una ricentralizzazione dello sviluppo. Alcune evidenze in Sicilia

2018

Le politiche di coesione territoriale dell’Unione europea mettono in discussione i principi dello sviluppo locale. Nonostante la Commissione europea abbia adottato un approccio place-based, sembra che le sue azioni di pianificazione soft si stiano muovendo in direzione di una centralizzazione delle funzioni decisionali. Lo sviluppo del PO FESR 2014-2020 in Sicilia nei settori del turismo e della cultura ne offre una concreta dimostrazione. The territorial cohesion policies of the European Union call into question the principles of local development. Although the European Commission has adopted a place-based approach, it seems that its actions of soft planning are moving towards a centraliza…

A Competence-based View on the Global Software Development Process

2015

The adoption of Global Software Development (GSD) models by software development companies is growing continuously. A variety of challenges such as temporal, geographical and socio-cultural distance are hindering global organizations to achieve potential benefits. As a result, organizations need support in how to overcome the challenges. The emphasis in the literature to date has typically focused on overcoming the challenges by providing tool support, management guidelines and processes. This follows the assumption that a well-established and validated process results in high quality output, not taking the actors within the process into account. While recognized as an important factor for …