Chitosan supported palladium catalyst. VI. Nitroaniline degradation

A chitosan‐supported palladium catalyst was prepared by immobilization of palladium on glutaraldehyde crosslinked chitosan followed by in situ chemical reduction. This catalyst was successfully used for the degradation of 4‐nitroaniline (4‐NA) in the presence of sodium formate, used as the hydrogen donor. The reaction product was 1,4‐phenylenediamine. The degradation was favored by acidic pH. A 10 to 15 excess of formate (compared to 4‐NA) is required to achieve complete degradation of the substrate. The reaction appears to be limited to the external layers of the catalyst: small particle size is required to optimize the degradation kinetics. Alternatively, an increase of catalyst dosage is required to increase kinetic rates but at the expense of palladium consumption. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1634–1642, 2004     

Data management scheme for parallel radiosity

The radiosity method is a very demanding process in terms of computing and memory resources. To cope with these problems, parallel solutions have been proposed in the literature. A new parallel solution, based on the use of a shared virtual memory, is proposed. It will be shown that this concept of SVM greatly simplifies the implementation of a parallel algorithm since distributed data are managed by the operating system. This new parallel radiosity algorithm has been implemented on an iPSC/2 hypercube using the SVM. The first results obtained with this algorithm are encouraging since the calculated efficiency curve is nearly linear.     

A multiharmonic method for non-linear vibration analysis

A multiharmonic method for analysis of non-linear dynamic systems submitted to periodic loa conditions is presented. The approach is based on a systematic use of the fast Fourier transform. The e linearization of the resulting equations in the frequency domain allows to obtain full quadratic converg rate.     

Transformation champ proche — champ lointain bidimensionnelle et monodimensionnelle appliquée à des mesures de SER

In high frequency thercs measurement of large target must be done at important distances, so the distance of measurement (Fraunhofer’s distance) R is given by R ≥ 2d² /λ where d is the tranversal length of the target and λ the radiation wavelength. In this paper we present a method for target that are large relative to the curvature of the spherical wavefront and the curvature of the cylindrical wavefront. A two-dimensional analytical algorithm transforms the spherical wave (near-field) measurement into the desired plane wave (far-field) and a one-dimensionnal analytical algorithm transforms the cylindrical wave (near-field) measurement into the desired plane wave (far-field). We present some results on simulations and measurements. A comparison of one-dimensional and two-dimensional methods demonstrates the efficiency of the two dimensional methods.     

Cell culture bags allow a large extent of ex vivo expansion of LTC-IC and functional mature cells which can subsequently be frozen: interest for a large-scale clinical applications

The aim of this study was to evaluate the ex vivo expansion of normal CD34+ cells in gas-permeable polypropylene bags suitable for clinical use. Cells were cultured for 14 days in serum-free medium supplemented with SCF, IL3, IL6, FLT3-1, G-CSF + MGDF or Epo. The bags supported the expansion of hematopoietic cells in a similar manner to small scale well or flask systems, allowing mean expansions of up to 2193-fold for total nucleated cells, 140-fold for CFU-GM and 66-fold for LTC-IC. Increasing the initial cell concentration from 5 x 10(3) to 1 x 10(5)CD34+ cells/ml induced the production of granulocytic cells with terminal differentiation while simultaneously decreasing the overall extent of expansion of the white blood cells produced. We tested the phagocytic activity and oxidative metabolism of the white blood cells produced. The percentage of phagocytic cells was 39+/-0.5% in expanded cultures derived from fractions initiated at 5 x 10(3), 10(4) or 10(5) cells/ml and 45+/-6% in cultured cells obtained from starting fractions containing 5 x 10(4) cells/ml, as compared to 58+/-4% in normal controls. A study of the potential for oxygen-dependent microbe killing showed that the expanded cells produced H2O2, although in lesser quantities than control cells. We subsequently investigated the possibility of freezing expanded cells. Total cell recovery after thawing was 45+/-4%, while recoveries of progenitors and stem cells ranged from 65 to 90%, without any influence of the initial cell concentration. This new approach could be of major interest for clinical practice, as it would allow evaluation of the quality of a graft prior to its infusion and employs experimental conditions which meet the criteria for potential clinical use.     

Transplantation of stromal cells transduced with the human IL3 gene to stimulate hematopoiesis in human fetal bone grafts in non-obese, diabetic-severe combined immunodeficiency mice

The non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mouse is a convenient host for human hematopoietic tissues and cells. Human fetal bone fragments engrafted subcutaneously in NOD-SCID mice sustain human hematopoiesis for several months. MS5 murine bone marrow stromal cells were transfected by electroporation with a plasmid containing the human interleukin-3 gene. As expected, stably transfected hu-IL3-MS5 cells supported human hematopoiesis in vitro more efficiently than MS5 cells. hu-IL3-MS5 cells were then injected intravenously into hu-NOD-SCID mice to test their ability to home to the mouse and/or human bone marrow, and to evaluate the role of hu-IL3 secretion on human hematopoiesis in vivo. hu-IL3 was detected in the mouse serum for up to an observation time of 8 weeks. hu-IL3-MS5 cells engrafted the bone marrow, spleen, liver and lungs of the mice but also the human bone graft. The presence of hu-IL3-MS5 cells in the human bone significantly stimulated local human hematopoiesis. This setting could be used to model the bone marrow homing of intravenously injected stromal cells or stromal cell precursors. The same experimental principle could also be applied in a therapeutic perspective to malignant human bone marrow hematopoiesis.     

EFFECTIVE STRESSES AND MICROSTRUCTURE IN CYCLICALLY DEFORMED 316L AUSTENITIC STAINLESS STEEL: EFFECT OF TEMPERATURE AND NITROGEN CONTENT

Abstract— This paper reports a study on the factors influencing dislocation slip during cyclic deformation of 316L austenitic stainless steel. TEM investigations show that low temperature and interstitial nitrogen content favour planar slip and lead to higher erective stress values. Measurements of effective and internal stresses with the Handfield-Dickson technique indicate that the contribution of nitrogen in the effective component is more important than that of temperature. It is deduced that nitrogen acts through a pinning effect, while low temperature exerts an effect on friction stress. The results also suggest that cyclic plasticity could modify the short range order leading to a redistribution of nitrogen.