Experimental and mathematical modelling of magnetically labelled mesenchymal stromal cell delivery

A key challenge for stem cell therapies is the delivery of therapeutic cells to the repair site. Magnetic targeting has been proposed as a platform for defining clinical sites of delivery more effectively. In this paper, we use a combined in vitro experimental and mathematical modelling approach to explore the magnetic targeting of mesenchymal stromal cells (MSCs) labelled with magnetic nanoparticles using an external magnet. This study aims to (i) demonstrate the potential of magnetic tagging for MSC delivery, (ii) examine the effect of red blood cells (RBCs) on MSC capture efficacy and (iii) highlight how mathematical models can provide both insight into mechanics of therapy and predictions about cell targeting in vivo. In vitro MSCs are cultured with magnetic nanoparticles and circulated with RBCs over an external magnet. Cell capture efficacy is measured for varying magnetic field strengths and RBC percentages. We use a 2D continuum mathematical model to represent the flow of magnetically tagged MSCs with RBCs. Numerical simulations demonstrate qualitative agreement with experimental results showing better capture with stronger magnetic fields and lower levels of RBCs. We additionally exploit the mathematical model to make hypotheses about the role of extravasation and identify future in vitro experiments to quantify this effect.     

Corrosion inhibition by naturally occurringsubstances—I. The effect of Hibiscus subdariffa (karkade) extract on the dissolution of Al and Zn

The thermometric, the weight-loss and the galvanostatic polarization techniques wereused to establish the inhibition of the dissolution of Al and Zn in HCl and NaOH by different concentrations of aqueous extract of Hibiscus subdariffa (Karkade). The extent of corrosion inhibition as measured by the three techniques is comparable. The results indicated that the additive acts by way of adsorption on both cathodic and anodic corrosion areas. Curves representing the variation of the reaction number (R.N.), in thermometric experiments, and the decrease in weight as a function of the concentration of the additive, are invariably sigmoid in nature. When present in enough amounts, the additive decreases the dissolution rate by as much as 85 per cent of the value recorded in its absence.     

Stoffaustausch zwischen flüssigem Eisen und Schlacke beim Sprühraffinationsverfahren

Erläuterung des Sprühraffinationsverfahrens, bei dem eine Schmelze mit inertem Gas verdüst wird und die entstehenden Metalltropfen durch eine Raffinationsschlacke fallen. Erörterung der Gesetzmäßigkeiten für die Stoffaustauschvorgänge zwischen Metalltropfen und Schlacke. Bestimmung der mittleren Tropfengröße beim Versprühen von kohlenstoffgesättigtem Roheisen. Untersuchung der Wirkung der Sprühraffination am Beispiel der Entschwefelung des Roheisens mit Schlacken des Systems CaO–CaF₂–Al₂O₃ bei 1600 °C. Ermittlung des Stoffübergangskoeffizienten des Schwefels für den umgekehrt transitorischen Phasenkontakt und Vergleich mit Werten bei anderen Techniken des Phasenkontaktes Metall-Schlacke.     

Theoretical Study of TiO2 Doped with Single and Double Impurities

Using first principles calculations within the density-functional theory (DFT) and the local density approximation (LDA), the electronic structure and magnetic properties of rutile TiO₂ doped with single and double-impurities Ti(Cr, Mn) O₂ has been investigated. The Korringa–Kohn–Rostoker coherent potential approximation (KKR-CPA) has been used. Chromium doping brings up a half-metallic appearance; it is due to the hybridization between the 3d state of chromium and the oxygen 2p state. The mechanism of the interatomic exchange in this case has been deducted as a double exchange. We also studied Mn doped TiO₂, which gave rise to ferromagnetism, due to the p–d exchange. We also study the advantage of codoping TiO₂ diluted magnetic oxide to find a suitable material to be used in spintronics.     

Oil: Source rock correlations of Al Baraka oil field,Komombo basin,South Egypt: An implication from biomarkers characteristics

The objectives of this study are the correlation between the oil samples recovered from the Lower Cretaceous reservoirs and Lower and Upper Cretaceous source rocks. The investigated biomarkers of five oils indicated the oils were derived from mixed marine and terrigenous (lacustrine) organic matter and deposited under suboxic to anoxic conditions. These oils were also generated from source rocks of high thermal maturity at the peak oil window. So, based on the molecular indicators of organic source input,depositional environment and maturity parameters of oils and extracts, we can conclude that the oil recovered from Al Baraka oil field were derived from Lower Cretaceous source rocks especially KomOmbo (B) source rocks where it reached the oil window. Furthermore, we can indicate that the other lower Cretaceous formations as Abu Ballas Formation will have the opportunity to generate and expel oil at the deeper part of the basin as shown in the eastern part of the basin.     

Assignment and Scheduling in Flexible Job-Shops by Hierarchical Optimization

In this paper, we propose a new hierarchical method for the flexible job-shop scheduling problem (FJSP). This approach is mainly adapted to a job-shop problem (JSP) with high flexibility and is based on the decomposition of the problem in an assignment subproblem and a sequencing subproblem. For the first subproblem, we propose two methods: the first one is based successively on a heuristic approach and a local search; the second one, however, is based on a branch-and-bound algorithm. The quality of the assignment is evaluated by a lower bound. For the second subproblem we apply a hybrid genetic algorithm to deal with the sequencing problem. Computational tests are finally presented.     

Monitoring fading rate of ultracapacitors using online characterization during power cycling

This paper deals with the ageing quantification of ultracapacitors in cycle-life tests. Typical micro- and mild-hybrid applications have been used to specify the test profiles in agreement with power requirements. Since ultracapacitors lifetime depends on the temperature, these profiles are adjusted to induce a given self-heating at the beginning of the power cycling tests. Ageing is evaluated thanks to the measurements of the electrical parameters changes. The good reproducibility of the characterization methods has allowed us to monitor the fading rate of ultracapacitors, from two manufacturers, with the proposed current profiles.     

A multiple access scheme for wireless access to a broadband ATM LANbased on polling and sectored antennas

An adaptive polling scheme for multiple access in a broadband wireless local area networks (LANs) is proposed. It is designed to accommodate asynchronous transfer mode (ATM) traffic with a large and variable range of bit rates. The radio architecture is microcellular, with switched sectored-beam antennas and a small frequency reuse factor. Features of the multiple access scheme include polling rate depending on a terminal's average bit rate, fixed-length frames divided into segments corresponding to base antenna sectors, and automatic-repeat-request (ARQ) for error control, combined with randomized sector segment ordering. The steady-state performance (cell loss, call blocking and dropping probabilities, waiting time, and buffer occupancy) are evaluated by simulation for an open indoor environment, and for handoff, ARQ, and simple power control enhancements; focusing mainly on the effects of the propagation and interference conditions     

DC electrical conductivity of some oligoazomethines

Six aromatic oligoazomethines were synthesized containing seven benzene rings each. The terminal rings were substituted with different groups, namely, H, Cl, NO₂, OH, OCH₃ and CH₃. The synthesis was carried out by condensing the para‐substituted benzaldehydes with benzidine to give the three‐ring compound, which was then condensed with terephthaldehyde to give the respective seven‐benzene‐ring oligomers. The oligomers were characterized by elemental analysis, electronic spectra, Fourier‐transform infrared and thermal analysis. The oligomers were used to investigate the effects of their molecular structure on their electronic spectra, as well as their thermal, electronic and electrical properties. The different conformers were reported and compared. The DC electrical conductivity variation of oligoazomethines was studied in the temperature range 300–500 K after annealing for 24 h at 100 °C and after doping with 5% I₂. An attempt was made to relate the DC electrical conductivity, electronic properties and thermal properties to the chain length, substituted groups and coplanarity. The fairly low conductivity obtained was attributed to the non‐linearity of the rings in the chain. The different groups (neutral, electron withdrawing or electron donating) attached at the ends of the oligomer showed no influence upon the conductivity of the different oligomers. The action of doping gave almost the same enhancement as that noticed in the case of a long‐chain polymer. The DC electrical conductivity was interpreted using the band energy model. The seven‐benzene‐ring oligomer gave the same DC electrical conductivity as the long‐chain polymer. Copyright © 2004 Society of Chemical Industry     

Argon irradiation damage at a Cu/Al2O3 interface for different alumina structures

The evolution of damages at a Cu/Al₂O₃ device interface after Ar⁺ irradiation, depending on alumina structure, and the effect of surface roughness on sputtering have been studied. A polycrystalline Cu/Al₂O₃ bilayer and polycrystalline Cu on amorphous alumina were irradiated with 400 keV Ar⁺ ion beam at doses ranging from 5 × 10¹⁶ to 10¹⁷ Ar⁺/cm² at room temperature. The copper layer thicknesses were between 100 and 200 nm. RBS analysis was used to characterize the interface modification and to deduce the sputtering yield of copper. The SEM technique was used to control the surface topography. A RBS computer simulation program was used to reproduce experimental spectra and to follow the concentration profile evolutions of different elements before and after ion irradiation. A modified TRIM calculation program which takes into account the sputtering yield evolution as well as the concentration variation versus dose gives a satisfactory reproduction of the experimental argon distribution. The surface roughness effect on sputtering and the alumina structure influence at the interface on mixing mechanisms are discussed.