Elastic proton-proton scattering: Excitation functions from 0.45 to 2.5 GeV

Excitation functions of the differential cross sections dσ/dgw, analyzing powers A_N and spin correlation parameters A_NN, A_SS and A_SL have been measured with internal targets at the Cooler Synchrotron COSY. Data were taken continously during the acceleration and deceleration of the internal beam for kinetic energies between 450 and 2500 MeV and scattering angles 30° σ_cm 90°. Details of the experimental method are presented. The results provide excitation functions and angular distributions of high precision and internal consistency. No evidence for narrow structures are found. Upper limits on the coupling of narrow resonances to elastic scattering in the mass range √s = 2.2…2.8 GeV are deduced. The data have significant impact on phase shift solutions.     

Study of the casting of sulfonated polyimide ionomer membranes: structural evolution and influence on transport properties

A casting process has been studied for charged polymers: the sulfonated polyimide ionomer membrane. The formation of the membrane has been followed by X-ray reflectivity as a function of temperature. The effect of equivalent weight has been also investigated. The thickness loss presents two regimes: the first one is linear vs time indicating that the models developed for noncharged polymer may be suitable for ionomers in the early period of drying. The second one corresponds to the loss of X-ray reflectivity signal. Moreover, the X-ray reflectivity signal seems to be correlated to the characteristic time of the sample drying. In complement, we have studied the influence of casting on the properties of the dried ionomer membranes. The transport coefficients of N(CH(3))(4)(+) ions confined in two kinds of membranes that were differently cast were measured. The results show that shearing the ionomer solution during casting may lead to an enhancement of the anisotropy of structure and of transport. Moreover, we have studied the effect of both interfaces on the ion transport properties through the dried membranes.     

On Mordell's Equation

In an earlier paper we developed an algorithm for computing all integral points on elliptic curves over the rationals Q. Here we illustrate our method by applying it to Mordell's Equation y²=x³⁺k for 0 k Z and draw some conclusions from our numerical findings. In fact we solve Mordell's Equation in Z for all integers k within the range 0 < | k | 10 000 and partially extend the computations to 0 < | k | 100 000. For these values of k, the constant in Hall's conjecture turns out to be C=5. Some other interesting observations are made concerning large integer points, large generators of the Mordell–Weil group and large Tate–Shafarevi groups. Three graphs illustrate the distribution of integer points in dependence on the parameter k. One interesting feature is the occurrence of lines in the graphs.     

Synthesis and characterization of ionic conducting sulfonated polybenzimidazoles

By copolymerization of the disodium‐2,2′‐disulfonate‐4,4′‐oxydibenzoic acid (SODBA), the 4,4′‐oxybis(benzoic acid) (OBBA) with the bis 3,4‐(diaminophenyl)sulfone (BDAPS), a series of high molecular weight sulfonated polybenzimidazoles (sPBI) were prepared by varying the ratio of monomers SODBA/OBBA. Polymers with ion exchange capacity (IEC) ranging from 0 to 3.2 meqH⁺/g were obtained. The chemical structure of the sPBI was confirmed by NMR, Fourier‐transform infra‐red (FTIR). Although the sPBI display a very poor solubility in organic solvents, they are, in the ammonium salt form, soluble in polar aprotic solvents such as DMF, NMP, or DMSO. Tough and ductile membranes from solution casting method were prepared. The water uptake and the ionic conductivity were determined at 30 and 90 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1732–1742, 2010     

Unusual transformations of difluorosilanone F<Subscript>2</Subscript>Si=O

The structure and properties of fluorosilicon polymer (fluorosil) formed by the reaction of phenyltrifluorosilane with aliphatic alcohols have been studied by the methods of IR, ¹⁹F, ²⁹Si NMR spectroscopy, high temperature mass-spectrometry, derivatography and atom emission analysis. Due to its high reactivity, this polymer readily reacts with glass of the reaction vessel extracting the ions of all metals entering into its composition. Fluorosil formed in a quartz, teflon or polypropylene reactors is characterized by low stability and is slowly decomposed to SiF₄ and SiO₂. Apparently, fluorosil is the product of incorporation of SiF⁴ into the SiO₂ matrix.     

Effect of polymeric additives on cavitation and radiated noise in water flowing past a circular cylinder

The present study is concerned with the effect of high molecular weight polymers on the cavitating flow around a cylinder. A decrease of the incipient cavitation number and disappearance of the transient cavitation regime are observed when polymers are added to the flow. Simultaneously, the radiated noise and the drag on the cylinder are substantially reduced for σ values above critical.     

Diffusion of macromolecular solutions in the turbulent boundary layer of a cylindrical pipe — Evolution of wall concentration

Summary In this paper, we are presenting a model of the evolution of the wall concentration of a macromolecular solution (PEO) annularly injected in a cylindrical pipe in a turbulent flow. This model valid for all diffusion zones is based on mathematical and physical considerations and proves to be in good agreement with the experimental data.

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Zusammenfassung Es wird ein Modell der Entwicklung der Wandkonzentration einer makromolekularen Lösung (PÄO) vorgestellt, die in einem wandnahen Ringspalt in die turbulente Strömung durch ein zylindrisches Rohr injiziert worden ist. Dieses für alle Diffusionszonen gültige Modell basiert auf mathematischen und physikalischen Betrachtungen und erweist sich für die Beschreibung der experimentellen Daten als gut geeignet.

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C _w wall concentration - C _i initial concentration before injection - L ₀ distance from the slot at which the wall concentration drops toe ^-1 of its original value - L _IT ,L _IF ,L _F characteristic lengths - L _I length scale of the second region - x downstream distance from the source - n _I ,n _T ,n _F characteristic exponents - K ₀,K _I ,K _F characteristic constants - ln natural logarithm - q _i flow rate of injection - Q _T flow rate - C _j =C _{i · q i} /Q _T concentration in homogeneous medium - A, B, C, m constants - p andq annex variables - Re Reynolds number With 7 figures