Speckle motion due to laser light scattering off non-homogeneous media

Non-homogeneous velocity distributions of light scattering particles generally result in a non-homogeneous motion of the speckle pattern. This has been shown theoretically and experimentally by considering the space-time intensity correlation function of light being scattered by particles within a shear flow.     

A comparison of high statistics measurements of the proton and deuteron structure functions

We present a detailed comparison of high statistics measurements of the structure functionF ₂(x, Q ²) from deep inelastic scattering of charged leptons on hydrogen and deuterium targets. It is found that the CERN results from the EMC and BCDMS Collaborations are both compatible with the lowQ ² electron scattering results from SLAC after an adjustment of the relative normalizations. We discuss the residual discrepancy between EMC and BCDMS which persists after this renormalization and find that the SLAC data are in better agreement with the steeperx dependence of the BCDMS results. A phenomenological parametrization ofF ₂(x, Q ²) is given.     

Optimisation théorique et expérimentale des caractéristiques géométriques et électriques du transistor à effet de champ à grille submicronique

Annals of Telecommunications - Les auteurs présentent ici les résultats d’une étude théorique et expérimental de l’influence des caractéristiques...     

Photochemistry of Chlorinated 2-Cycloalkenones

The 6-chloro-2-cyclohexenones 3, 6 and 11 , and the 5-chloro-2-cyclopentenone 15 were newly synthesized. The results obtained with compounds 3 and 15 in photocycloadditions to olefins show that the oxetane vs. cyclobutane product ratio is reduced by the substitution of florine by chlorine in the α′ -position of the enone. No oxetanes are formed in the intramolecular photocycloaddition of 6. Compound 11 does not photoadd to olefins. The newly synthesized 2-chloro-3-cyclohexenones 8 and 9 are also photostable towards light of λ=366 nm, but π-π*-excitation (λ=254 nm) in pentane leads to the formation of 4,4-dimethylcyclohexanone (29) .     

Synthesis of novel amphiphilic pyridinylboronic acids

Novel 3‐alkoxy‐2‐pyridinylboronic acids bearing, in their 3‐position, linear alkoxy or perfluoroalkoxy chains with n carbon atoms (n = 6, 8, 10, 12 and 18) 2a – 2g are synthesized from 2‐bromo‐3‐pyridinol, which is the common starting product. Our alternative procedure for the synthesis of 3‐alkoxy‐2‐bromopyridine in a phase‐transfer catalysis system is to carry out the reaction in a solid–liquid medium in the presence of a quaternary ammonium salt under microwave irradiation. General and versatile synthetic methods have been developed for preparation of a large variety of new 2‐pyridinylboronic acids bearing two alkylated or perfluoroalkylated side chains with an ether junction in the 3‐position. Copyright © 2003 John Wiley & Sons, Ltd.     

Some nonconforming mixed box schemes for elliptic problems

In this article, we introduce three schemes for the Poisson problem in 2D on triangular meshes, generalizing the FVbox scheme introduced by Courbet and Croisille [1]. In this kind of scheme, the approximation is performed on the mixed form of the problem, but contrary to the standard mixed method, with a pair of trial spaces different from the pair of test spaces. The latter is made of Galerkin‐discontinuous spaces on a unique mesh. The first scheme uses as trial spaces the P¹ nonconforming space of Crouzeix‐Raviart both for u and for the flux p = ?u. In the two others, the quadratic nonconforming space of Fortin and Soulie is used. An important feature of all these schemes is that they are equivalent to a first scheme in u only and an explicit representation formula for the flux p = ?u. The numerical analysis of the schemes is performed using this property. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 355–373, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10003     

Pyrido[1,2-a]benzimidazoles et analogues: Synthese et etude structurale

The Cyclisation of 1-(2-propynyl)2-aminomethylbenzimidazoles leads to pyrido[1,2-a]benzimidazoles. The proposed mehcanism involves in a first step hetrocyckisation followed by a rerrangemnet. This Process is suitable for some aza analoga of benzimidazole.     

OCTA-ALKYL ZINC PHTHALOCYANINES: POTENTIAL PHOTOSENSITIZERS FOR USE IN THE PHOTODYNAMIC THERAPY OF CANCER

The synthesis, characterization and electronic spectra of a series of nine 1,4,8,11,15,18,22,25-octa-alkyl zinc phthalocyanines (ZnPc), potential photosensitizers for the photodynamic therapy of cancer, are described. The substituents on the phthalocyanine (Pc) macrocycle “red-shift” the absorbance maximum, in cyclohexane, of all nine members of this series to a value of 703 ± 2 nm, with a corrected fluorescence emission maximum for the octadecyl derivative of 715 nm. The solubilities and degree of aggregation of six examples in cyclohexane have been measured. The highest homologue, the octadecyl derivative, remains essentially unaggregated to a concentration of 1.5 ± 10^?4 mol dm^?3. The photostability of this Pc has been examined and the compound shown to be sensitive to photooxidation processes, which lead to its decomposition to 3,6-fcw-decylphthalimide. Known singlet oxygen quenchers inhibit the photodecomposition. In a comparative study, the octadecyl ZnPc underwent a more rapid photodecomposition than the corresponding metal-free derivative.     

Linear and angular annelation effects on the 13C NMR spectra of tricyclic aromatic ketones. 1—annelated indanones

Carbon-13 NMR chemical shifts are reported for nine tricyclic aromatic ketones formally derived from indanone. The influences of remote ring size, as well as linear, angular exo and angular endo ketone orientation are examined. Results are compared with available ¹H NMR data. For indanone itself, based on selective ¹H decoupling experiments, a recently reported CIDNP derived ¹³C signal assignment is shown to be in error.     

Parabolic Differential Equations in Ordered Banach Spaces of Bounded Functions

Let A be a set, and let E be the Banach space of bounded functions : A R, equipped with its natural order. With a rectangle R = (a,b) × (0,T] let F(x,t,) : R × E E be a bounded, continuous function satisfying a local Hölder condition and being quasimonotone increasing with respect to . Then there exists a solution u: [a,b] × [0,T] E of the problem ut(x,t) – uxx(x,t) = F(x,t,u(x,t)) ((x,t) R), u(x,t) = 0 ((x,t) R R).