Triple solutions for a nonlocal functional boundary value problem by leggett–williams theorem

The existence of triple solutions for a second-order nonlocal functional boundary value problem is proved by using a fixed-point theorem on cones in Banach spaces due to Leggett and Williams. The obtained results are new even in the ordinary case for three-point boundary value problems discussed quite recently in [Xiaoming He and Weigao Ge (2002). Triple solutions for second-order three-point boundary value problems. J. Math. Anal. Appl., 268, 256–265].     

Ba deposition and oxidation on theta-Al2O3/NiAl(100) ultrathin films. Part II: O2(g) assisted Ba oxidation

Ba deposition on a theta-Al(2)O(3)/NiAl(100) substrate and its oxidation with gas-phase O(2) at various surface temperatures are investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and temperature programmed desorption (TPD) techniques. Oxidation of metallic Ba by gas-phase O(2) at 800 K results in the growth of 2D and 3D BaO surface domains. Saturation of a metallic Ba layer deposited on theta-Al(2)O(3)/NiAl(100) with O(2)(g) at 300 K reveals the formation of BaO(2)-like surface states. These metastable peroxide (O(2)(2-)) states are converted to regular oxide (O(2-)) states at higher temperatures (800 K). In terms of thermal stability, BaO surface layers (theta(Ba) < 5 ML) that are formed by O(2)(g) assisted oxidation on the theta-Al(2)O(3)/NiAl(100) substrate are significantly more stable (with a desorption/decomposition temperature of c.a. 1050 K) than the thick (2 < theta(Ba) < 10 ML) metallic/partially oxidized Ba layers prepared in the absence of gas-phase O(2), whose multilayer desorption features appear as low as 700 K.     

Effect of barium loading on the desulfation of Pt-BaO/Al2O3 studied by H2 TPRX, TEM, sulfur K-edge XANES, and in situ TR-XRD

Desulfation processes were investigated over sulfated Pt-BaO/Al2O3 with different barium loading (8 and 20 wt %) by using H2 temperature programmed reaction (TPRX), transmission electron microscope (TEM) with energy dispersive spectroscopy (EDS), sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and in situ time-resolved X-ray diffraction (TR-XRD) techniques. Both sulfated samples (8 and 20 wt %) form sulfate species (primarily BaSO4) as evidenced by S K-edge XANES and in situ TR-XRD. However, the desulfation behavior is strongly dependent on the barium loading. Sulfated Pt-BaO8/Al2O3, consisting predominantly of surface BaO/BaCO3 species, displays more facile desulfation by H2 at lower temperatures than sulfated Pt-BaO20/Al2O3, a material containing primarily bulk BaO/BaCO3 species. Therefore, after desulfation with H2 up to 1073 K, the amount of the remaining sulfur species on the former, mostly as BaS, is much less than that on the latter. This suggests that the initial morphology differences between the two samples play a crucial role in determining the extent of desulfation and the temperature at which it occurs. It is concluded that the removal of sulfur is significantly easier at lower barium loading. This finding can potentially be important in developing more sulfur resistant LNT catalyst systems.     

Ba deposition and oxidation on theta-Al2O3/NiAl(100) ultrathin films. Part I: Anaerobic deposition conditions

Room-temperature Ba deposition on an oxygen-terminated theta-Al(2)O(3)/NiAl(100) ultrathin film substrate under ultrahigh vacuum (UHV) conditions is studied using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) techniques. In addition, Ba oxidation by the ions of the alumina substrate at 300 K < T < 1200 K in the absence of a gas-phase oxidizing agent is investigated. Our results indicate that at room temperature Ba grows in a layer-by-layer fashion for the first two layers, and Ba is partially oxidized. Annealing at T < 700 K results in further oxidation of the Ba species, whereas annealing at higher temperatures leads to loss of Ba from the surface via desorption and subsurface diffusion.     

A note on Keldysh's perturbation formalism

The expansion theorem of quantum field theoy relating Heisenberg operators to asymptotic free-field operators is rewritten by means of the time-path technique, originally due to Schwinger, which to date has only found application in statistical mechanics. The theorem is combined with Bogoliubov's initial condition of vanishing correlations in the infinite past to rederive Keldysh's perturbation scheme for non-equilibrium statistical Green's functions.     

Multipurpose radiomatic automated flow liquid scintillation counter system for measurement of burst or delayed chemiluminescence reactions: Model-drug inhibition with luminol-dependent myeloperoxidase

We have developed an automated, highly sensitive system for the detection of chemiluminescent reactions that are rapid or burst-type reactions. Approximately 25 samples per hour can be run with human myeloperoxidase-H₂O₂-high Cl^?. This is due to the difficulties of washing out cationic myeloperoxidase from the flow cell. Various nonsteroidal anti-inflammatory drugs were run against the enzyme and the most inhibitory were ascorbate and BW755C at doses around 10^?7M, while sulindac sulfide and indomethacin were the most inhibitory at 10^?6M range. Aspirin and salicylate were partially effective at the 10^?5M range. This type of CL system should be generally useful for a variety of fast CL reactions, because it is automated, with continuous recording, and integration of peaks is possible.     

Ion equilibria in THF solutions of models of “living” methacrylonitrile oligomers with Li+ counterion

The electro-chemical characteristics of isobutyronitrile lithium (P₁Li) and 2-lithio-4-cyano-2,4-dimethylpentanenitrile (P₂Li) are studied. The dissociation constants K of P₁Li and P₂Li are of the order of 10^?11M and show that in THF mainly contact ion pairs exist. The lower value of K for P²Li is an indication for intramolecular complexation between the counterion and the cyano group, next to the active center. Both compounds tend to form ion triples. The results obtained show that in THF the nitrile group of the second monomer unit participates both in intra- and intermolecular interactions with the counterion.     

Feedback Grid Generation via Monotone Discretization for Two-point Boundary-Value Problems

We describe a uniformly enclosing discretization technique formildly nonlinear boundary-value problems. This method allowsus to derive a grid generation principle, using the distancebetween the lower and upper solutions to control the grid-generationprocedure. The convergence of the proposed feedback gridgenerationmethod is proved.     

NO2 adsorption on BaO/Al2O3: the nature of nitrate species

Temperature programmed desorption, infrared spectroscopy, and (15)N solid state NMR spectroscopy were used to characterize the nature of the nitrate species formed on Al(2)O(3) and BaO/Al(2)O(3) NO(x) storage/reduction materials. Two distinctly different nitrate species were found: surface nitrates that are associated with a monolayer BaO on the alumina support, and a bulk-like nitrate that forms on this thin BaO layer. The surface nitrates desorb as NO(2) at lower temperatures than do the bulk-like nitrates, which decompose as NO+O(2) at higher temperatures. The amount of NO(x) stored in the monolayer nitrate is proportional to the surface area of the catalyst, while that in the bulk nitrate increases with BaO coverage.     

Analyse multielementaire instrumentale des phosphates marocains par photoactivation nucleaire

Photonuclear activation and high resolution gamma-ray spectrometry have been used to determine non-destructively the concentrations of 25 trace elements in Maroccan phosphate rock. The activation was simultaneously performed for phosphate samples and multielement standards in the bremsstrahlung beam of a linear electron accelerator at 18 and 30 MeV maximum energies. Gamma-ray spectra were recorded with a 79 cm³ Ge(Li) detector and a programmable analyzer IN 96. A detailed study of interferences was carried out. Limits of detection between 0.5 and 125 μg·g^?1 were obtained.