Experimental and numerical investigation of a phase change material: Thermal-energy storage and release

The application of phase change materials (PCMs) for solar thermal-energy storage capacities has received considerable attention in recent years due to their large storage capacity and isothermal nature of the storage process. This study deals with the comparison of numerical and experimental results for a PCM conditioned in a parallelepipedic polyefin envelope to be used in passive solar walls. The experimental results were obtained by use of a genuine set-up involving heat flux sensors and thermocouples mounted on two vertical aluminium exchanger plates squeezing the samples. Numerical predictions were obtained with a custom one-dimensional Fortran code and a two-dimensional use of Fluent. Both methods showed a very good agreement with experimental observations for the melting process (?5%). However during solidification, both numerical codes failed to predict the phase change process accurately, the maximal relative error was as high as 57% (with an average of 8%).     

Modelling of cooking-cooling processes for meat and poultry products

Traditional cooking‐cooling of processed meat and poultry products is industrially carried out in smokehouses or autoclaves. A mathematical model was developed to simulate these operations. Equations, describing heat transfer and thermal destruction of micro‐organisms and quality characteristics, were solved numerically. The model was validated experimentally for heat transfer and energy consumption and was used to perform a sensitivity analysis. Input variables were: process time (PT), smokehouse temperature (T_SH), bologna size (diameter, D and height, H), surface heat transfer coefficients (h_heat and h_cool), product thermal diffusivity (α_heat and α_cool). Output variables were: product core temperature (T_c), core and volume‐average lethality (P_cm and P_vm) and cook (C_c and C_v) values as well as surface (Q_s) and volume‐average (Q_v) quality retention, total specific energy consumption (En) and energy efficiency (Ce). Multiple linear regression models were developed to predict C_c and C_v from five inputs and used to obtain acceptable deviation ranges.     

Integration of diamond in fully-depleted silicon-on-insulator technology as buried insulator: A theoretical analysis

We examine here by electro-thermal simulation tools (SILVACO's Atlas) a configuration of Silicon-On-Insulator substrate for Fully-Depleted MOSFET architectures, incorporating diamond as buried insulator, and compare it with traditional silicon dioxide BOX for the future technological nodes of the ITRS (90 nm and below). Our aim is to give major trends to be followed in order to optimize diamond integration from electrical and thermal points of view, constraints that must be kept in mind in parallel with the technological work on thin diamond films. In this theoretical study, we perform a benchmarking between SiO₂ and diamond BOX. We first point out that the BOX thickness should not be more than few hundred nanometers to maintain electrical performances. From thermal point of view, we demonstrate that the replacement of 100 nm thick buried oxide by a 100 nm thick diamond layer can lead to about 50% reduction of the temperature when only 33% decrease can be obtained with Ultra Thin SiO₂ BOX (20 nm). Furthermore, thick diamond BOX avoids the parasitic capacitances issue that reduces Ultra Thin BOX devices working frequency.     

Libre parcours moyen dans la phase solide des materiaux frittés

A simple mathematical model is used to predict the evolution of the mean free path in the solid phase in a sintered material. The knowledge of the volume fraction of the solid phase and of the particle coordination number are only required. Good agreement is observed between experimental data and the purposed relationship.     

A Fullerene-Like Ball in a Second Century Roman Mosaic?

A fullerene-like ball is found in a second century mosaic from Porta Marina Roman Baths near Ostia. Although it could be an hexadecahedral ball (28 vertices, 4 hexagonal and 12 pentagonal faces), it is probably an erroneous representation of a dodecahedral ball.     

Detection of single photoluminescent diamond nanoparticles in cells and study of the internalization pathway

Diamond nanoparticles are promising photoluminescent probes for tracking intracellular processes, due to embedded, perfectly photostable color centers. In this work, the spontaneous internalization of such nanoparticles (diameter 25 nm) in HeLa cancer cells is investigated by confocal microscopy and time-resolved techniques. Nanoparticles are observed inside the cell cytoplasm at the single-particle and single-color-center level, assessed by time-correlation intensity measurements. Improvement of the nanoparticle signal-to-noise ratio inside the cell is achieved using a pulsed-excitation laser and time-resolved detection taking advantage of the long radiative lifetime of the color-center excited state as compared to cell autofluorescence. The internalization pathways are also investigated, with endosomal marking and colocalization analyses. The low colocalization ratio observed proves that nanodiamonds are not trapped in endosomes, a promising result in prospect of drug delivery by these nanoparticles. Low cytotoxicity of these nanoparticles in this cell line is also shown.     

Functionalized carbon nanotubes are non-cytotoxic and preserve the functionality of primary immune cells

Carbon nanotubes are emerging as innovative tools in nanobiotechnology. However, their toxic effects on environment and health have become an issue of strong concern. In the present study, we address the impact of functionalized carbon nanotubes (f-CNTs) on cells of the immune system. We have prepared two types of f-CNTs, following the 1,3-dipolar cycloaddition reaction (f-CNTs 1 and 2) and the oxidation/amidation treatment (f-CNTs 3 and 4), respectively. We have found that both types of f-CNTs are uptaken by B and T lymphocytes as well as macrophages in vitro, without affecting cell viability. Subsequently, the functionality of the different cells was analyzed carefully. We discovered that f-CNT 1, which is highly water soluble, did not influence the functional activity of immunoregulatory cells. f-CNT 3, which instead possesses reduced solubility and forms mainly stable water suspensions, preserved lymphocytes' functionality while provoking secretion of proinflammatory cytokines by macrophages.     

The autochrome process

Abstract

The autochrome was the first successful commercial colour process. It was invented by Louis and Auguste Lumiere at the tum of the century, patented in 1903 and produced until the 1950s on a sheet film called ‘Filmcolor’. Many articles were published between 1903 when the autochrome process was unveiled to the public, and 1935 when the decline of the screen process began and the first colour films with chromogenic development appeared. There are detailed deseriptions of the plate's range of use, its characteristies and processing, but these publications are very sketchy as to the nature of the components. The most detailed documents, on which this article is based, are the ‘report on the titles and work of Louis Lumiere’ published in 1918, the factory notebooks written by Louis Lumiere or M. Perrigot,¹ and the archives of the Lumiere firm, which are now scattered in various locations.     

Biocompatibility of heparin-grafted hemodialysis membranes: impact on monocyte chemoattractant protein-1 circulating level and oxidative status

This prospective observational study aimed at evaluating efficacy and biocompatibility performances of the new heparin-coated Evodial dialyzers with/without systemic heparin reduction. After a 4-week wash-out period with reference polysulfone F70S dialyzers, 6 hemodialysis patients were sequentially dialyzed with Evodial, F70S, and Evodial dialyzers using 30% heparin reduction, each period of treatment was 4 weeks. Removal rates (RR) (urea, creatinine, and β2-microglobulin), dialysis dose, and instantaneous clearances (urea and creatinine) were measured as well as inflammatory (C-reactive protein, fibrinogen, interleukin 6, tumor necrosis factor α, and monocyte chemoattractant protein-1) and oxidative stress (OS) (superoxide anion, homocysteine, and isoprostanes) parameters at the end of each study period. Patients treated with Evodial or F70S dialyzers for 4 weeks presented comparable dialysis efficacy parameters including urea and creatinine RR, dialysis dose and instantaneous clearances. By contrast, a significantly lower but reasonably good β2-microglobulin RR was achieved with Evodial dialyzers. Regarding biocompatibility, no significant difference was observed with inflammation and OS except for postdialysis monocyte chemoattractant protein-1 which significantly decreased with Evodial dialyzers. Thirty percent heparinization reduction with Evodial dialyzers did not induce any change in inflammation but led to an improvement in OS as demonstrated by a decrease in postdialysis superoxide production and predialysis homocysteine and isoprostane. This bioactive dialyzer together with heparin dose reduction represents a good trade-off between efficacy and biocompatibility performance (improvement in OS with a weak decrease in efficacy) and its use is encouraging for hemodialysis patients not only in reducing OS but also in improving patient comorbid conditions due to lesser heparin side effects.     

Ant colony optimization algorithm for the Euclidean location-allocation problem with unknown number of facilities

This paper addresses the Euclidean location-allocation problem with an unknown number of facilities, and an objective of minimizing the fixed and transportation costs. This is a NP-hard problem and in this paper, a three-stage ant colony optimization (ACO) algorithm is introduced and its performance is evaluated by comparing its solutions to the solutions of genetic algorithms (GA). The results show that ACO outperformed GA and reached better solutions in a faster computational time. Furthermore, ACO was tested on the relaxed version of the problem where the number of facilities is known, and compared to existing methods in the literature. The results again confirmed the superiority of the proposed algorithm.