22 research outputs found
An Adaptation of the Hoshen-Kopelman Cluster Counting Algorithm for Honeycomb Networks
We develop a simplified implementation of the Hoshen-Kopelman cluster counting
algorithm adapted for honeycomb networks.
In our implementation of the algorithm we assume that all nodes in the network
are occupied and links between nodes can be intact or broken.
The algorithm counts how many clusters there are in the network and determines
which nodes belong to each cluster. The network information is stored into
two sets of data. The first one is related to the connectivity of the nodes and
the second one to the state of links. The algorithm finds all clusters in only
one scan across the network and thereafter cluster relabeling operates on a
vector whose size is much smaller than the size of the network. Counting
the number of clusters of each size, the algorithm determines the cluster
size probability distribution from which the mean cluster size parameter can
be estimated. Although our implementation of the Hoshen-Kopelman algorithm
works only for networks with a honeycomb (hexagonal) structure, it
can be easily changed to be applied for networks with arbitrary connectivity
between the nodes (triangular, square, etc.).
The proposed adaptation of the Hoshen-Kopelman cluster counting algorithm
is applied to studying the thermal degradation of a graphene-like honeycomb
membrane by means of Molecular Dynamics simulation with a Langevin thermostat.
ACM Computing Classification System (1998): F.2.2, I.5.3
Anomalous diffusion of a tethered membrane: A Monte Carlo investigation
Using a continuum bead-spring Monte Carlo model, we study the anomalous
diffusion dynamics of a self-avoiding tethered membrane by means of extensive
computer simulations. We focus on the subdiffusive stochastic motion of the
membrane's central node in the regime of flat membranes at temperatures above
the membrane folding transition. While at times, larger than the characteristic
membrane relaxation time , the mean-square displacement of the center
of mass of the sheet, , show the normal Rouse diffusive behavior with a diffusion
coefficient scaling as with respect to the number of
segments in the membrane, for short times we observe a {\em
multiscale dynamics} of the central node, , where the
anomalous diffusion exponent changes from to
, and then to , before diffusion turns
eventually to normal. By means of simple scaling arguments we show that our
main result, , can be related to particular mechanisms of
membrane dynamics which involve different groups of segments in the membrane
sheet. A comparative study involving also linear polymers demonstrates that the
diffusion coefficient of self-avoiding tethered membranes, containing
segments, is three times smaller than that of linear polymer chains with the
same number of segments.Comment: 14 pages, 6 figures, accepted for publicaton in PR
Step bunching with both directions of the current: Vicinal W(110) surfaces versus atomistic scale model
We report for the first time the observation of bunching of monoatomic steps
on vicinal W(110) surfaces induced by step up or step down currents across the
steps. Measurements reveal that the size scaling exponent {\gamma}, connecting
the maximal slope of a bunch with its height, differs depending on the current
direction. We provide a numerical perspective by using an atomistic scale model
with a conserved surface flux to mimic experimental conditions, and also for
the first time show that there is an interval of parameters in which the
vicinal surface is unstable against step bunching for both directions of the
adatom drift.Comment: 17 pages, 10 figure
Presence of IL-8 Gene Polymorphism and IL-8 Serum Levels in Patients with Chronic Periodontitis - Literature Review
Multifactorial nature of chronic periodontitis is well known. The data indicate that the bacteria of subgingival biofilm (with their presence at high levels, too), as well as the immune response of the organism, genetic components and environmental factors play a significant role in the development of periodontal destructive disease. On the one hand the strong relationship between microorganisms from the “red complex” has been proved. On the other hand the initiation and progression of chronic periodontitis has been verified, as well. The presence of bacterial metabolic products and other substances (lipopolysaccharides, enzymes and toxins) results in increased expression of proinflammatory cytokines and release of active agents leading to the development of a local tissue lesion. Thus, the negative (destructive) side of the immune response is expressed and associated with the immunopathological nature of periodontitis. Literary data testify the importance of interleukin-8 (IL-8) in regulating the inflammatory response to bacterial infection and suggest its association with susceptibility to periodontitis
CO2 Adsorption on Modified Mesoporous Silicas: The Role of the Adsorption Sites
The post-synthesis procedure for cyclic amine (morpholine and 1-methylpiperazine) modified mesoporous MCM-48 and SBA-15 silicas was developed. The procedure for preparation of the modified mesoporous materials does not affect the structural characteristics of the initial mesoporous silicas strongly. The initial and modified materials were characterized by XRD, N2 physisorption, thermal analysis, and solid-state NMR. The CO2 adsorption of the obtained materials was tested under dynamic and equilibrium conditions. The NMR data revealed the formation of different CO2 adsorbed forms. The materials exhibited high CO2 absorption capacity lying above the benchmark value of 2 mmol/g and stretching out to the outstanding 4.4 mmol/g in the case of 1-methylpiperazin modified MCM-48. The materials are reusable, and their CO2 adsorption capacities are slightly lower in three adsorption/desorption cycles