Electrospinning of cyclodextrin functionalized chitosan/PVA nanofibers as a drug delivery system

A new type of nanofibrous structure from chitosan bearing carboxymethyl-β-cyclodextrin (CS-g-β-CD) as a novel drug delivery system was synthesized by grafting carboxymethyl-β-cyclodextrin (CM β-CD) onto chitosan (CS) in the presence of water soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as the condensing agent and N-hydroxysuccinimide (NHS). Defect free mats containing CS-g-β-CD have been fabricated using electrospinning of an aqueous solution of poly(vinyl alcohol) (PVA)/CS-g-β-CD blends. The morphology and diameter of the electrospun nanofibers were examined by scanning electron microscopy (SEM). The average fiber diameter was in the range of 130–210 nm. SEM images showed that the morphology and diameter of the nanofibers were mainly affected by weight ratio of the blend at constant applied voltage. The results revealed that increasing CS-g-β-CD content in the blends decreases the average fiber diameter. It was observed that the PVA/CS-g-β-CD nanofibrous mat provided a slower release of the entrapped drug in compare to PVA/CS nanofibrous mat.     

Gadolinium DOTA chelates featuring alkyne groups directly grafted on the tetraaza macrocyclic ring: synthesis, relaxation properties, "click" reaction, and high-relaxivity micelles

This paper reports on the synthesis and relaxivity properties of tetraacetic DOTA-type chelating agents featuring one or two alkyne groups directly grafted on the tetraaza macrocyclic ring and available for "click" reactions with azide-bearing substrates. The racemic DOTAma ligand bearing one alkyne group was obtained by a bisaminal template route. The same approach was used to prepare ligand DOTAda substituted by two alkyne groups located on two adjacent carbon atoms. The S,S enantiomer of DOTAda was also prepared by a "crab-like" condensation. This ligand is the first example of a DOTA derivative featuring two reactive functions adjacent to each other on the macrocyclic ring. A triacetic monoalkyne ligand (DO3ma) was also synthesized for comparison purposes. NMR studies indicate that the Yb(III) chelates of DOTAma and DOTAda adopt two conformations in solutions in which the tetraaza ring is rigidified. The hydration state of the Eu(III) chelates was determined by luminescence spectroscopy, and the water exchange time of the Gd(III) complexes was measured by (17)O NMR. Ring substitution accelerates the water exchange. These data were used to interpret nuclear magnetic relaxation dispersion curves of the Gd(III) chelates. Two long aliphatic chains have been added to DOTAda by a "click" procedure to form the (C18)(2)DOTAda ligand. The corresponding Gd(III) complex forms micelles of unusually high relaxivity presumably because of the close proximity of the aliphatic chains on the macrocyclic ring that ensures a rigid double anchoring into the micelles.     

Experimental study of blade thickness effects on the overall and local performances of a Controlled Vortex Designed axial-flow fan

The purpose of this work is to study the effects of blade thickness on the performances of an axial-flow fan. Two fans that differ only in the thickness of their blades were studied. The first fan was designed to be part of the cooling system of an automotive vehicle power unit and has very thin blades. The second fan has much thicker blades compatible with the rotomoulding conception process. The overall performances of the fans were measured in a test bench designed according to the ISO-5801 standard. The curve of aerodynamics characteristics (pressure head versus flow-rate) is slightly steeper for the fan with thick blades, and the nominal point is shifted towards lower flow-rates. The efficiency of the thick blades fan is lower than the efficiency of the fan with thin blades but remains high on a wider flow-rate range. The mean velocity fields downstream of the rotors are very similar at nominal points with less centrifugation for the thick blades fan. Moreover, the thick blades fan maintains an axial exit-flow on a wider range of flow-rates. The main differences concern local properties of the flow: phase-averaged velocities and wall pressure fluctuations strongly differ at the nominal flow-rates. The total level of fluctuations is lower for the thick blades fan that for the thin blades fan and the spectral decomposition of the wall fluctuations and velocity signals reveal more harmonics for the thick blades fan, with less correlation between the different signals. For this kind of turbomachinery, the use of thick blades could lead to a good compromise between aerodynamic and acoustic performances, on a wider operating range.     

Identification of internal cracks in a three-dimensional solid body via Steklov–Poincaré approaches

This Note deals with the identification of internal planar cracks inside a three-dimensional elastic body via two approaches relying on domain decomposition using elastostatic measurements. These approaches consist in recasting the problem in terms of primal or dual Steklov–Poincaré equations. The primal approach is a straightforward continuation to the elastic Cauchy problem of the work presented in J. Ben Abdallah (2007) [1] which is devoted to the Cauchy problem for the scalar Laplace equation. The numerical performances of these formulations are compared.     

Ionization and recombination in plasmas

Ionization and recombination in a plasma are considered. They give rise to a system of kinetic equations with cubic source terms. An existence theorem is proved for such a system.     

A library of 3-aryl-4,5-dihydroisoxazole-5-carboxamides

Parallel solution phase methods for the preparation of a 72-membered 3-aryl-4,5-dihydroisoxazole-5-carboxamide library is reported. The reaction order (nitrile oxide 1,3-dipolar cycloaddition followed by amide formation, or vice versa) was investigated both experimentally and computationally to determine which route would result in the highest yields, minimize purification efforts, and give higher 1,3-dipolar cycloaddition regioselectivity. Automated preparative HPLC was used to purify the final products to >or=90% purity on a 10+ mg scale.     

Quantum Dot-Based Biosensor for the Detection of Human T-Lymphotropic Virus-1

A method was developed to identify human T-lymphotropic virus-1 (HTLV-1) using cadmium–tellurium quantum dots. Two probes including the biotin-labeled acceptor and NH2-reporter probes with target DNA were hybridized. The resulted sandwich complex was immobilized on a well containing streptavidin. The quantum dot solution was added to the sandwich complex, conjugated with the amine group of reporter probe, and emission spectra of the quantum dots were recorded. The biosensor response was linear with HTLV-1 concentrations from 10 pg/µl to 0.24?ng/µl, with a detection limit of 19.5 pg/µl. The assay may be successfully used for detection of long nucleic acids.     

Energy Gain Investigation in Fast Ignition ICF with Electron Ignition Beam by Changing Fuel Characteristics

Fast ignition is a method in inertial confinement fusion （ICF） in which an ignition spark in pre-compression fuel is formed by an ultra-intense laser beam. In applying this method, a hot spot is built by relative electrons which are produced by the ultra-intense laser beam. For a better understanding, a fuel energy gain curve based on density is drawn and it can be observed that the ignition by an electron beam has the maximum energy gain. The maximum energy gain has been observed in equimolar DT fuel with a density of 500g/cma and in fuel with tritium （10%） with a density of 1000g/cm^3.     

Preparation of Silica‐bonded Propyl‐diethylene‐triamine‐N‐sulfamic Acid as a Recyclable Catalyst for Chemoselective Synthesis of 1,1‐Diacetates

A simple and efficient procedure for the preparation of silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid (SPDTSA) by reaction of 3‐diethylenetriamine‐propylsilica (DTPS) and chlorosulfonic acid in chloroform is described. Silica‐bonded propyl‐diethylene‐triamine‐N‐sulfamic acid is employed as a recyclable catalyst for the synthesis of 1,1‐diacetates from aromatic aldehydes and acetic anhydride under mild and solvent‐free conditions at room temperature. Catalyst could be recycled for several times without any additional treatment.