Towards a more realistic modeling of solid foam: Use of the pentagonal dodecahedron geometry

The geometric structure of a solid foam is approached using a pentagonal dodecahedron as the unit cell. Important properties of the foam (specific surface area, pressure drop, external fluid-solid mass transfer) are well represented and successfully compared with experiments. The approach enables accounting for triangular or cylindrical struts and solid accumulation at their meeting points. Knowledge of the void fraction and mean strut diameter (or pore diameter) are sufficient for estimating any geometric characteristics. The model has been tested with foams of porosity ranging from 0.75 to 0.98.     

Timing is everything: using fluidics to understand the role of temporal dynamics in cellular systems

In biology, it is not only the magnitude of a chemical stimulus that determines cellular response; it is becoming increasingly clear that the timing of the stimulus is vastly important as well. Currently there is a paucity of data regarding cell behavior under dynamic stimulation conditions that are representative of what occurs in vivo. This is, at least in part, attributed to the lack of appropriate tools for generating time-varying stimulatory signals in highly diverse patterns. Fluidics on the macro and micro scale has provided a practical platform for dynamically stimulating cells in a highly controllable manner at physiological and supra-physiological time scales (seconds to a few hours). These fluidic systems have contributed substantially to our understanding of how cells process and react to dynamic stimulatory environments; while these setups provide the means to analyze and manipulate cellular behavior in these types of environments on the single-cell level and on a high-throughput level, improvements can be made to these platforms to enhance their utility for high-impact biological investigations of temporal dynamics.     

Effect of osmosis time on structure, texture and pectic composition of strawberry tissue

The effect on strawberry tissue of an osmotic step applied at atmospheric pressure for different lengths of time, was analysed. In this work, the specific influence of osmotic treatments with sucrose solutions at 25 °C on cellular structure, texture, pectin composition and their relationship are discussed. Osmotic dehydration induced a significant texture loss: The longer the immersion time, the higher the texture loss. From 1 h onwards of osmosis there was a gradual disconnection and breakdown of the tissue, with a loss of shape of cellular walls together with loss of turgor pressure. A good agreement was obtained between texture, structure changes and pectic composition modifications. Besides a pectin solubilization, there was an hemicelluloses solubilization, most likely due to an accelerated ripening of strawberry fruit, linked to the anaerobic conditions, caused by a sugar peripheral layer formation.     

Assessing cellular automata model behaviour using a sensitivity analysis approach

Rapid advances in computer and geospatial technology have made it increasingly possible to design and develop urban models to efficiently simulate spatial growth patterns. An approach commonly used in geography and urban growth modelling is based on cellular automata theory and the GIS framework. However, the behaviour of cellular automaton (CA) models is affected by uncertainties arising from the interaction between model elements, structures, and the quality of data sources used as model input. The uncertainty of CA models has not been sufficiently addressed in the research literature. The objective of this study is to analyze the behaviour of a GIS-based CA urban growth model using sensitivity analysis (SA). The proposed SA approach has both qualitative and quantitative components. These components were operationalized using the cross-tabulation map, KAPPA index with coincidence matrices, and spatial metrics. The research focus was on the impacts of CA neighbourhood size and type on the model outcomes. A total of 432 simulations were generated and the results suggest that CA neighbourhood size and type configurations have a significant influence on the CA model output. This study provides insights about the limitations of CA model behaviour and contributes to enhancing existing spatial urban growth modelling procedures.     

Stability and Existence of Periodic Solutions of Periodic Cellular Neural Networks with Time-Vary Delays

By using the continuation theorem of Mawhins coincidence degree theory and constructing a suitable Lyapunov function, some new sufficient conditions are obtained ensuring existence and global asymptotical stability of periodic solution of cellular neural networks with periodic coefficients and delays, which do not require the activation functions to be differentiable and monotone nondecreasing. A numerical example is given to illustrate that the criteria are feasible. These results are helpful to design globally asymptotically stable and periodic oscillatory cellular neural networks.     

The Effect of Iron Oxide Magnetic Nanoparticles on Smooth Muscle Cells

Recently, magnetic nanoparticles of iron oxide (Fe₃O₄, γ-Fe₂O₃) have shown an increasing number of applications in the field of biomedicine, but some questions have been raised about the potential impact of these nanoparticles on the environment and human health. In this work, the three types of magnetic nanoparticles (DMSA-Fe₂O₃, APTS-Fe₂O₃, and GLU-Fe₂O₃) with the same crystal structure, magnetic properties, and size distribution was designed, prepared, and characterized by transmission electronic microscopy, powder X-ray diffraction, zeta potential analyzer, vibrating sample magnetometer, and Fourier transform Infrared spectroscopy. Then, we have investigated the effect of the three types of magnetic nanoparticles (DMSA-Fe₂O₃, APTS-Fe₂O₃, and GLU-Fe₂O₃) on smooth muscle cells (SMCs). Cellular uptake of nanoparticles by SMC displays the dose, the incubation time and surface property dependent patterns. Through the thin section TEM images, we observe that DMSA-Fe₂O₃ is incorporated into the lysosome of SMCs. The magnetic nanoparticles have no inflammation impact, but decrease the viability of SMCs. The other questions about metabolism and other impacts will be the next subject of further studies. Song Zhang and Xiangjian Chen contributed equally to this work.     

A combination of Monte Carlo simulation and cellular automata for computing the availability of complex network systems

This paper combines Monte Carlo simulation and cellular automata for computing the availability of a complex network system and the importance measures of its elements.     

Storage Products and Linear Control of Derivations

Various automata using certain kinds of tuples of storages are defined in the literature. In this paper we investigate some possibilities to define such storages independently of automata by a restricted type of product on storages, called concatenation. It is shown that there is a strong relation between automata with concatenated pushdowns and restricted classes of linear controlled grammars. Using this result, some relations between hierarchies of automata with an ascending number of concatenated pushdowns and some well-known hierarchies of controlled grammars follow naturally.     

Image security system using recursive cellular automata substitution

This paper presents a novel image security system based on the replacement of the pixel values using recursive cellular automata (CA) substitution. This proposed image encryption method exhibits the properties of confusion and diffusion because of the characteristics of CA substitution are flexible. The salient features of the proposed image encryption method are its losslessness, symmetric private key encryption, very large number of secret keys, and key-dependent pixel value replacement. Simulation results obtained using some color and gray-level images clearly demonstrate the strong performance of the proposed image security system.