106 research outputs found
Modelling of a CCP-RF discharge used for the simulation of Titanâs chemistry
This paper reports the modelling of CCP-RF discharges (13.56 MHz) in pure nitrogen, produced within a cylindrical parallel-plate reactor, similar to a GEC reference cell surrounded by a lateral grounded grid, at 0.1-2 mbar pressures and 10-50 W coupled powers. This study is a first step in simulating Titanâs chemistry at laboratory scale, using the PAMPRE experiment. Modelling results are compared with experimental measurements of the average electrondensity, and the self-bias potential at the polarized electrode
Targeting of T/Tn Antigens with a Plant Lectin to Kill Human Leukemia Cells by Photochemotherapy
Photochemotherapy is used both for solid tumors and in extracorporeal treatment of various hematologic disorders. Nevertheless, its development in oncology remains limited, because of the low selectivity of photosensitizers (PS) towards human tumor cells. To enhance PS efficiency, we recently covalently linked a porphyrin (TrMPyP) to a plant lectin (Morniga G), known to recognize with high affinity tumor-associated T and Tn antigens. The conjugation allowed a quick uptake of PS by Tn-positive Jurkat leukemia cells and efficient PS-induced phototoxicity. The present study was performed: (i) to evaluate the targeting potential of the conjugate towards tumor and normal cells and its phototoxicity on various leukemia cells, (ii) to investigate the mechanism of conjugate-mediated cell death. The conjugate: (i) strongly increased (Ă1000) the PS phototoxicity towards leukemic Jurkat T cells through an O-glycan-dependent process; (ii) specifically purged tumor cells from a 1â¶1 mixture of Jurkat leukemia (Tn-positive) and healthy (Tn-negative) lymphocytes, preserving the activation potential of healthy lymphocytes; (iii) was effective against various leukemic cell lines with distinct phenotypes, as well as fresh human primary acute and chronic lymphoid leukemia cells; (iv) induced mostly a caspase-independent cell death, which might be an advantage as tumor cells often resist caspase-dependent cell death. Altogether, the present observations suggest that conjugation with plant lectins can allow targeting of photosensitizers towards aberrant glycosylation of tumor cells, e.g. to purge leukemia cells from blood and to preserve the normal leukocytes in extracorporeal photochemotherapy
Real-Space Mesh Techniques in Density Functional Theory
This review discusses progress in efficient solvers which have as their
foundation a representation in real space, either through finite-difference or
finite-element formulations. The relationship of real-space approaches to
linear-scaling electrostatics and electronic structure methods is first
discussed. Then the basic aspects of real-space representations are presented.
Multigrid techniques for solving the discretized problems are covered; these
numerical schemes allow for highly efficient solution of the grid-based
equations. Applications to problems in electrostatics are discussed, in
particular numerical solutions of Poisson and Poisson-Boltzmann equations.
Next, methods for solving self-consistent eigenvalue problems in real space are
presented; these techniques have been extensively applied to solutions of the
Hartree-Fock and Kohn-Sham equations of electronic structure, and to eigenvalue
problems arising in semiconductor and polymer physics. Finally, real-space
methods have found recent application in computations of optical response and
excited states in time-dependent density functional theory, and these
computational developments are summarized. Multiscale solvers are competitive
with the most efficient available plane-wave techniques in terms of the number
of self-consistency steps required to reach the ground state, and they require
less work in each self-consistency update on a uniform grid. Besides excellent
efficiencies, the decided advantages of the real-space multiscale approach are
1) the near-locality of each function update, 2) the ability to handle global
eigenfunction constraints and potential updates on coarse levels, and 3) the
ability to incorporate adaptive local mesh refinements without loss of optimal
multigrid efficiencies.Comment: 70 pages, 11 figures. To be published in Reviews of Modern Physic
Embedment of Liposomes into Chitosan Physical Hydrogel for the Delayed Release of Antibiotics or Anaesthetics, and its First ESEM Characterization
International audienceThis work describes the characterization of an original liposomes/hydrogel assembly, and its application as a delayed-release system of antibiotics and anaesthetics. This system corresponds to drugloaded liposomes entrapped within a chitosan (CS) physical hydrogel. To this end, a suspension of pre-formed 1,2-dipalmitoyl-sn-glycero-3phosphocoline liposomes loaded with an antibiotic (rifampicin, RIF), an anaesthetic (lidocaine, LID), or a model fluorescent molecule (carboxyfluorescein, CF), was added to a CS solution. The CS gelation was subsequently carried out without any trace of chemical cross-linking agent or organic solvent in the final system. Liposomes within the resulting gelled CS matrix were characterized for the first time by environmental scanning electron microscopy. The release of drugs from the assembly was investigated by fluorescence or UV spectroscopy. The cumulative release profiles of RIF and LID (and also CF for comparison) were found to be lower from the "drug-in-liposomes-in-hydrogel" (DLH) assembly in comparison to "drug-in-hydrogel" (DH) system
Modeling of capacitively coupled radio-frequency discharges in nitrogen
abstract #KTP.029This paper reports the modeling of capacitively coupled radio-frequency discharges (13.56 MHz) in pure nitrogen, produced within a cylindrical parallel-plate reactor, similar to a GEC reference cell surrounded by a lateral grounded grid, at 0.2-3 mbar pressures and 5 -30 W coupled powers. This reactor is used to simulate, at laboratory scale, the N2/CH4 chemistry of Titan's atmosphere. We have used a 2D, time-dependent fluid-type code to describe the transport of electrons and positive ions N+2 and N+4 in the reactor, coupled to a 0D kinetic code for N2. The fluid code solves the charged particle and the electron mean energy transport equations, coupled to Poisson's equation for the RF electric potential. The kinetic code solves the electron Boltzmann equation and the rate balance equations of 45 vibrationally excited states and 7 electronically excited states of the N2 molecule, yielding a set of electron transport parameters and rate coefficients for the charged particle production and destruction. Model results are compared to measurements of the self- bias potential, the average electron density, and the line intensities of the FNS(0-0) [N+2 (B,0)-N+2 (X,0)] and of the SPS(0-2) [(N2(C,0)-N2(B,2)]
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