Existence results for a degenerated nonlinear elliptic partial differential equation

The aim of this paper is to establish the existence of weak solutions to a steady state two-dimensional irrotational compressible flow around a thin profile. This flow is described by the small disturbance equations. If the speed of sound exceeds the fluid one, the governing equations remain elliptic. But when the fluid speed is beyond the sound one, the flow becomes locally hyperbolic and shock waves arise. For a modified elliptic model, using convexity arguments, we prove the existence of a solution which is the solution to the first model when the flow remains subsonic.     

Identification of the Physical Parameters Used in the Thermo-Hygro-Mechanical Model

This paper describes different methods used to identify a large number of physical parameters of the thermo-hygro-mechanical coupling model. This model is developed on the basis of mechanics of porous media and deals with the prediction of response of a structure submitted to thermal, hygrometric and mechanical loading. The aim of this work is mainly to propose some experimental methods for the determination of physical parameters used previously in the model such as hygrometric parameters (liquid Biot's coefficient b _l , vapour and liquid permeability _v, _l and tangent capillary modulus N _ll). Thermal parameters such as thermal conductivity (), specific heat (C) and the thermo-hydrous expansion coefficient ( _i ^p ) have been identified using some works published previously. The different physical parameters were identified in the case of cement mortar without taking into account the influence of hysteresis.     

Assay of whole blood (6S)-5-CH3-H4folate using ultra performance liquid chromatography tandem mass spectrometry

Folates act as essential coenzymes in many biological pathways, including the synthesis and methylation of DNA. Low folate concentration in serum and whole blood (WB) is associated with several disease conditions. We describe a stable-isotope-dilution ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the quantification of (6S)-5-CH(3)-H(4)folate (where H(4)folate is tetrahydrofolate) and non-CH(3)-H(4)folate [sum of HCO-H(4)folate, (6R)-5,10-CH(+)-H(4)folate, (6R)-5,10-CH(2)-H(4)folate, (6S)-H(4)folate, dihydrofolate, and folic acid] in WB. The assay includes a solid-phase extraction procedure after the hemolysis and deconjugation. The method was linear over the concentration range from 0.2 to 200 nmol/L. The limits of detection were 0.40 nmol/L or lower for the folate forms. The interassay coefficients of variation were 7.4% for (6S)-5-CH(3)-H(4)folate and 15.4% for non-CH(3)-H(4)folate. For the folate forms, the recoveries were between 97.1% and 102.7%. Sample preparation caused the generation of artificial folic acid in WB and serum in a dose-dependent manner, which can lead to misinterpretation of the results. The use of antioxidants could not prevent the formation of folic acid. The median fasting WB folate concentrations from 42 nonsupplemented and nonfortified adults were 576 nmol/L (6S)-5-CH(3)-H(4)folate and 73.6 nmol/L non-CH(3)-H(4)folate, and 1,206 nmol/L (6S)-5-CH(3)-H(4)folate and 155 nmol/L non-CH(3)-H(4)folate for 35 adults who had taken 500 μg of folic acid, 50 mg of vitamin B(6), and 500 μg of vitamin B(12) per day orally for 6 months. In conclusion, the UPLC-MS/MS method is fast and has a good sensitivity and selectivity for WB folates. We observed a dose-dependent oxidation of (6S)-H(4)folate, which resulted in the formation of artificial folic acid in serum and WB. To minimize this effect, we recommend a fast sample preparation.     

Structural investigations on sodium-lead borophosphate glasses doped with vanadyl ions

Electron paramagnetic resonance (EPR), optical absorption, and FT-IR spectra of vanadyl ions in the sodium-lead borophosphate (Na(2)O-PbO-B(2)O(3)-P(2)O(5)) (SLBP) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO(2+) ions. The spin Hamiltonian parameters g and A are found to be independent of the V(2)O(5) content and temperature. The values of the spin Hamiltonian parameters indicate that the VO(2+) ions in SLBP glasses are present in octahedral sites with tetragonal compression. The population difference between Zeeman levels (N) is calculated as a function of temperature for an SLBP glass sample containing 1.0 mol % VO(2+) ions. From the EPR data, the paramagnetic susceptibility (χ) is calculated at different temperatures, and the Curie constant (C) is calculated from the 1/χ versus T graph. The optical absorption spectra of the glass samples show two absorption bands, and they are attributed to V(3+) and V(4+) ions. The optical band gap energy (E(opt)) and Urbach energy (ΔE) are calculated from their ultraviolet absorption edges. It is observed that, as the vanadium ion concentration increases, E(opt) decreases and ΔE increases. The study of the IR absorption spectrum depicts the presence of BO(3), BO(4), PO(3), PO(4), and VO(5) structural units.     

Multimeric cyclic RGD peptides as potential tools for tumor targeting: solid-phase peptide synthesis and chemoselective oxime ligation

The alpha v beta 3 integrin receptor plays an important role in human metastasis and tumor-induced angiogenesis. Targeting this receptor may provide information about the receptor status of the tumor and enable specific therapeutic planning. Solid-phase peptide synthesis of multimeric cyclo(-RGDfE-)-peptides is described, which offer the possibility of enhanced integrin targeting due to polyvalency effects. These peptides contain an aminooxy group for versatile chemoselective oxime ligation. Conjugation with para-trimethylstannylbenzaldehyde results in a precursor for radioiododestannylation, which would allow them to be used as potential tools for targeting and imaging alpha v beta 3-expressing tumor cells. The conjugates were obtained in good yield without the need of a protection strategy and under mild conditions.     

Additions D'α-chloronitriles sur les olefines par catalyse redox

α-Chloronitriles are shown to add to α-olefins and conjugated dienes, with ferrous chloride or preferably cuprous chloride in the presence of 2,2′-bipyridyl or 1,10-phenanthroline as catalysts     

The behavior of poly(amino acids) containing l‐cysteine and their block copolymers with poly(ethylene glycol) on gold surfaces

Poly(ethylene glycol) (PEG) is often used to biocompatibilize surfaces of implantable biomedical devices. Here, block copolymers consisting of PEG and l ‐cysteine‐containing poly(amino acid)s (PAA's) were synthesized as polymeric multianchor systems for the covalent attachment to gold surfaces or surfaces decorated with gold nanoparticles. Amino‐terminated PEG was used as macroinitiator in the ring‐opening polymerization, (ROP), of respective amino acid N‐carboxyanhydrides (NCA's) of l ‐cysteine (l ‐Cys), l ‐glutamate (l ‐Glu), and l ‐lysine (l ‐Lys). The resulting block copolymers formed either diblock copolymers, PEG‐b‐p(l ‐Glu_x‐co‐l ‐Cys_y) or triblock copolymers, PEG‐b‐p(l ‐Glu)_x‐b‐p(l ‐Cys)_y. The monomer feed ratio matches the actual copolymer composition, which, together with high yields and a low polydispersity, indicates that the NCA ROP follows a living mechanism. The l ‐Cys repeat units act as anchors to the gold surface or the gold nanoparticles and the l ‐Glu repeat units act as spacers for the reactive l ‐Cys units. Surface analysis by atomic force microscopy revealed that all block copolymers formed homogenous and pin‐hole free surface coatings and the phase separation of mutually immiscible PEG and PAA blocks was observed. A different concept for the biocompatibilization of surfaces was followed when thiol‐terminated p(l ‐Lys) homopolymer was first grafted to the surface and then covalently decorated with HOOC‐CH₂‐PEG‐b‐p(Bz‐l ‐Glu) polymeric micelles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 248–257     

DC Electrical Conductivity of Some Oligoazomethines Doped with Nanotubes

Three aromatic oligoazomethines containing seven benzene rings each were synthesized. The terminal rings were substituted with different organic groups; namely, OH, H, and NO₂. Synthesis was carried out according to the literature by condensing the para-substituted benzaldehydes with benzidine to give the three rings compound, which is then condensed with terephthaldehyde to give the respective seven benzene rings oligomer. The oligomers were used to investigate the effects of molecular structure on the electronic structure, as well as electronic and electrical properties. DC electrical conductivity variation of oligoazomethines is studied in the temperature range 300–500 K after annealing for 24 h at 100°C and after doping with 25 and 50 wt% Multi Wall Nanotubes (MWNTs). An attempt is made to relate DC electrical conductivity and electronic properties to chain length, substituted groups and coplanarity. The different groups attached to the ends showed a small effect on conductivity of the different oligomers in the following order: electron donating > neutral > electron withdrawing groups. Oligoazomethines-MWNTs gave a value of (10^?4 Scm^?1) as the highest electrical conductivity at higher temperatures. DC electrical conductivity was interpreted using the band energy model. The narrow-gap activation energies noted suggest its application in formulation of photovoltaic panels.