DRYING OF TOBACCO PARTICLES IN A MOBILISED BED

The drying performance of a novel device capable of mobilising a bed of fibrous materials is evaluated. The drying kinetic of the vegetable product used for this work, cut lamina tobacco particles, was determined from fixed bed experiments. A falling-rate period was observed for the entire drying curve. The results showed that the drying rate is controlled by internal mass transfer mechanism for gas superficial velocities above 0.8 m/ s. The proposed model is based on an effective liquid diffusion coefficient that varies with solids temperature according to an Arrhenius-type relationship. Batch drying experiments were carried out in the mobilised bed apparatus under various conditions of inlet air temperature, humidity and flowrate. Assuming perfect mixing and no internal resistance to heat transfer for the solids, the performance of the mobile bed can be predicted using the proposed internal liquid diffusion model     

Comparability of in Vitro Tests for Bioactive Nanoparticles: A Common Assay to Detect Reactive Oxygen Species as an Example

The release of reactive oxygen species (ROS) during the electron transport of mitochondrial aerobic respiration is the major source of ROS. However, contact between cells and nanoparticles (NPs) can also induce release of ROS, leading to an imbalance towards the pro-oxidative state. At low levels of ROS production, cells initiate a protective response to guarantee their survival, but an excess of ROS can damage cellular compounds such as membranes and various organelles, or directly cause genotoxicity. Thus an elevated level of ROS is an important indicator of cellular stress and an accurate recording of this parameter would be very informative. ROS can be measured by various assays, but all known assays measuring and quantifying ROS possess certain weaknesses. The problems and challenges of quantitatively detecting ROS in vitro using the 2′,7′-dichlorodihydrofluorescein (DCF) assay is discussed as an example. In addition, we debate the difficulties in finding a suitable and stable chemical reaction control for the DCF assay (or other ROS-detecting assays). As a conclusion, we believe that using 3-morpholinosydnonimine hydrochloride (Sin-1) as a ROS inducer in the DCF assay is feasible only qualitatively. However, a quantitative measurement of the absolute amount of ROS produced and a quantitative comparison between experiments is (at the moment) impossible.     

Low-Temperature Route to Lead Magnesium Niobate

Lead magnesium sniobate, Pb(Mg_1/3Nb_2/3)O₃ (PMN), was prepared by a sol-gel technique using alkoxide precursors. The hydrolysis-condensation mechanism leads to a translucent gel which is dried under hypercritical conditions to avoid collapse of the porous texture. After drying, the aerogel exhibits a B-deficient pyrochlore structure which progressively inserts magnesium oxide when the temperature increases. Near 700°C, this pyrochlore phase completely transforms into the PMN-perovskite phase. Above 1000°C, the loss of lead oxide leads to the destabilization of the PMN-perovskite with formation of an A-deficient pyrochlore phase.     

DETERMINATION METHOD OF VARIABLE DIFFUSION COEFFICIENTS OF HYGROSCOPIC MATERIAL FROM DRYING RATE CURVES OF THE SINGLE PARTICLE

The concentration dependency of diffusion coefficients of hygroscopic materials can usually only be calculated by cumbersome experimental techniques.

Taking the diffusion rate in the fictious steady state with the same mean moisture concentration as in the regular regime of the drying process of a spherical hygroscopic particle (which means the drying period not influenced by initial moisture distributions) into account, a simple method is proposed to estimate the dependency of diffusion coefficients on the moisture concentration for hygroscopic materials from drying rate curves of the single particle.     

Prévalence de la dépression chez les personnes séropositives au VIH: Une recension des écrits.

Summarizes prevalence studies of depression conducted on HIV- positive persons. Results of the studies generally suggest that depressive disorders are not more frequent in HIV-positive individuals than in HIV-negative male homosexuals or in the population as a whole. Data, however, suggest a stronger prevalence of depression in HIV-positive homosexual males than in heterosexual males. On the other hand, research results indicate that a life history of depression is frequent with HIV-positive individuals. Data also reveal that homosexual males, whether or not they are HIV-positive, have a higher prevalence of life history of depression. The authors suggest that this vulnerability to depression may be more associated with homosexuality than with an eventual seroconversion and propose research avenues on this subject. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactions of lithium and sodium aluminium hydride with sodium or lithium hydride. Preparation of a new alumino-hydride of lithium and sodium LiNa2AlH6

A study of the reactions of MAlH₄ with M′H (where M, M′ = Li, Na) has been carried out under various conditions of temperature and pressure. A new mixed hydride LiNa₂AlH₆ has been obtained. The X-ray structure has been determined on a Philips PW 1120 diffractometer and the product crystallises into a fcc structure with a cell having the dimension $\text{a}\text{= 7.405}\text{A}\text{?}$. Its diffraction pattern is very close to that of the high temperature modification of Na₃AlH₆ which possesses the ideal fcc cryolite structure. The thermal stability has been studied by DSC and the enthalpy of decomposition has been calculated and compared with the values of the other mixed hydrides of lithium and sodium     

Influence de la petrographie sur les caracteristiques physiques et mecaniques de granulats calcaires de lorraine

Limestones with different textures and petrographic composition were chosen for study: polyparies limestones, oolitic limestone and micritic limestone. These rocks are characterized by the study of their porosity and their texture with a Scanning Electron Microscope, by the measurement of the longitudinal elastic waves and of quality index. Uniaxal compression tests were performed, with a servo-controlled testing machine. Aggregates produced from these rocks were tested with Los Angeles and Microdeval machines. The experimental reslts were compared with S.E.M. observations. We compare also surface aspects of the aggregates before and after mechanical test, so fracture pattern of grains.     

La quantification vectorielle des signaux: approche algébrique

Spherical vector quantization (svq)consists of quantizing separately on the one hand the norm of a vector and, on the other hand, its orientation.Implementing such quantizer requires a set of normalized vectors (points on the unit sphere) which are the possible rounded-off values for the vector’s orientation. A clever way to design such a quantizer consists of taking a spherical subset from a regular point lattice. In particular a fast algorithm is given for the Gosset lattice in 8 dimensions. A second algorithm, equally optimal, is given for the Leech lattice in 24 dimensions. The performances of such quantizers for white Gaussian noise is compared to information theory limits. Finally, the application of these techniques for encoding speech residual is discussed.     

Control of an exoskeleton robot arm with sliding mode exponential reaching law

Robots are now working not only in human environments but also interacting with humans, e.g., service robots or assistive robots. A 7DoFs robotic exoskeleton MARSE-7 (motion assistive robotic-exoskeleton for superior extremity) was developed as an assistive robot to provide movement assistance and/or ease daily upper-limb motion. In this paper, we highlight the nonlinear control of MARSE-7 using the modified sliding mode exponential reaching law (mSMERL). Conventional sliding control produces chattering which is undesired for this kind of robotic application as it causes damage to the mechanical structure. Compared to conventional sliding control, our approach significantly reduces chattering and delivers a high dynamic tracking performance. The control architecture was implemented on a field-programmable gate array (FPGA) in conjunction with a RT-PC. In experiments, trajectory tracking that corresponds to typical passive arm movement exercises for single and multi joint movements were performed to evaluate the performance of the developed robot and the controller. Experimental results demonstrate that the MARSE-7 can effectively track the desired trajectories.