Synthesis of a new class of uridine phosphorylase inhibitors

A new series of potent uridine phosphorylase inhibitors have been prepared from barbituric acid. Among them, 1-[(2-hydroxyethoxy)methyl]-5-)(m--benzyloxy)benzylbarbituric acid ( 37 , BBBA) is the most promising having a K_i value of 1.1 ± 0.2 nM with uridine phosphorylase from human liver. The new inhibitors are easily synthesized and are better inhibitors of human uridine phosphorylase than their uracil counterparts.     

Online extraction and determination of octylglucoside by reversed-phase high-performance liquid chromatography with evaporative light-scattering detection

A reversed-phase high-performance liquid chromatography method using evaporative light-scattering detection is developed for the determination of residual octylglucoside (OG) levels after a detergent exchange step for in-process samples of a vaccine antigen. The reversed-phase column not only provides separation of the OG but also functions as an extraction column to remove the vaccine antigen from the sample, thereby eliminating off-line sample manipulations. In addition to column selection, the mobile phase is optimized to enhance extraction and separation. The vaccine antigen is irreversibly bound to the column, allowing nonprotein components to interact with the column for separation and elution. The assay is linear over the range of 0.00050-0.050% OG. Precision tested at 0.0010% and 0.0050% OG is 2.9% and 7.2% relative standard deviation, respectively. The limits of quantitation and detection are determined to be 0.00050 and 0.000125% OG, respectively. Accuracy is determined to be 103 and 98%, based on spike recoveries of 0.0010% and 0.0050% OG, respectively.     

Surface properties of the three-dimensional one-component plasma

Extending earlier work by us Badialiet al. [J. Phys. C: Solid State Phys. 16:2183 (1983)] we give further evidence for the usefulness of using spherical boundaries to calculate the bulk and surface properties of the three-dimensional onecomponent plasma (OCP) by Monte Carlo. Results are reported for the density profile of a “charged” OCP and for the pair distribution function parallel to the surface of an “open” system and of a neutral OCP near a hard wall. The charge fluctuations are calculated.     

Effective interactions in the colloidal suspensions from hypernetted-chain theory

The hypernetted-chain (HNC) Ornstein-Zernike integral equations are used to determine the properties of simple models of colloidal solutions where the colloids and ions are immersed in a solvent considered as a dielectric continuum and have a size ratio equal to 80 and a charge ratio varying between 1 and 4000. At an infinite dilution of colloids, the effective interactions between colloids and ions are determined for ionic concentrations ranging from 0.001 to 0.1 mol/l and compared to those derived from the Poisson-Boltzmann theory. At finite concentrations, we discuss on the basis of the HNC results the possibility of an unambiguous definition of the effective interactions between the colloidal molecules.     

Buffer layer effect in nanostructured tin electrodeposition on insulating and conducting substrates

The electroplating techniques for metal aggregates and films deposition commonly use an electric current to reduce metal ions in solution, but are restricted to conducting substrate. This new electrochemical technique permits coating of insulating or conducting substrates with metals having controlled aggregate size and growth speed. The basis of our approach is the progressive outward growth of the metal from an electrode in contact with the substrate, with the cell geometry chosen in such a way that the electron current providing the reduction passes through the growing deposit. The nanostructured deposit is composed of branched nanoaggregates from a quasi-continuous film to a more dendritic morphology dependant on current conditions. This approach has been used to elaborate tin electrodeposited thin films composed of a homogeneous distribution of nanoparticles on conducting or insulating substrates. In our works, when a non-continuous buffer gold coating is used, spontaneous mixing of tin atoms into AuSn nanoparticles takes place even at room temperature forming a nanostructured fractal film, if the substrate is conducting or insulating. Without a gold buffer layer, the deposit is composed of large pure tin micro-crystals with a large size distribution, less adapted to tin oxide nanoparticle formation. Indeed, from these tin metal deposits, the final goal is to elaborate functional nanostructured tin oxide films by oxidation for gas sensor applications.     

Nanoparticles from vesicle polymerization: Characterization and kinetic study

The polymerization of isodecyl acrylate (ISODAC) in vesicles made from an anionic surfactant—sodium di-2-ethylhexyl phosphate (SEHP)—and from water is studied by ¹H-NMR, transmission electron microscopy, and quasielastic light scattering. High polymerization rates and high conversion rates are achieved with both water-soluble initiator, K₂S₂O₈ (potassium persulfate), and oil-soluble initiator, AIBN (azoisobisbutyronitrile). ISODAC is probably located inside the vesicle bilayer(s) because of its high hydrophobicity. Particles stable at room temperature with a mean diameter of about 50 nm are obtained. Kinetic orders of ISODAC polymerization are determined and the characterization of the resulting particles during and after polymerization are studied. © 1996 John Wiley & Sons, Inc.     

Proposed search for a fourth neutrino with a PBq antineutrino source

Several observed anomalies in neutrino oscillation data can be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few eV(2). We show that this hypothesis can be tested with a PBq (ten kilocurie scale) (144)Ce or (106)Ru antineutrino beta source deployed at the center of a large low background liquid scintillator detector. In particular, the compact size of such a source could yield an energy-dependent oscillating pattern in event spatial distribution that would unambiguously determine neutrino mass differences and mixing angles.     

Formation of gallaoxetanes: C-O activation of 1,2-epoxybutane by ground-state Ga atoms

(69/71)Ga atoms were reacted with 1,2-epoxybutane and its isotopomers, 1,2-epoxybutane-1,1-d(2) (CH(3)CH(2)CHOCD(2)) and 1,2-epoxybutane-2-d(1) (CH(3)CH(2)CDOCH(2)), under matrix-isolation conditions. The novel gallaoxetanes CH(3)CH(2)CHCH(2)GaO and CH(3)CH(2)CHCH(2)OGa, resulting from the insertion of the metal atom in the C(1)-O and C(2)-O bonds, respectively, of the 1,2-epoxybutane, were detected by EPR spectroscopy. The Ga and H hyperfine interaction (hfi) values of the gallaoxetanes, calculated using a DFT method, were used to help assign the EPR spectra. A third Ga-centered species, detected at 190 K, underwent spectral changes similar to those of the C(2)-O insertion product upon isotopic substitution of the 1,2-epoxybutane. Although the Ga hfi for this species was 36% smaller than that of the C(2)-O insertion product, the values for the H hfi were similar, suggesting that the carrier of the spectrum was the C(2)-O insertion product where Ga was perturbed by the matrix constraints. The alkyl radical CH(3)CH(2)(?CH)CH(2)OGa, resulting from ring-opening at the C(2)-O bond of 1,2-epoxybutane, was observed at temperatures below 150 K. This radical has been implicated in the formation of the C(2)-O insertion product. The unusually small value found for two of the β-hydrogens of the alkyl radical is discussed.