Generalized Bethe-Faddeev wave functions

Bethe-Faddeev wave functions are generalized toN-body clusters. A comparison made between the Bethe approximation and the Day approximation in the three body cluster indicates that the two approximations should be competitive for the higher body clusters.     

Anisotropic propagation of weak discontinuities in flows of thermally conducting and dissociating gases

The object of the present investigation is to study the anisotropic propagation of weak discontinuities in flows of thermally conducting and dissociating gases. The velocity of propagation of the wave frcnt is determined. A set of differential equations governing the growth and decay of weak discontinuities are obtained and solved. It is found that if the sonic wave is a compressive wave of order 1, then it terminates into a shock wave after a critical timet _c which has been determined. It is also observed that the effects of heat conduction and dissociation are to decrease the duration of time by which a weak discontinuity will generate into a shock wave.     

Near infrared and visible tunability from a diode pumped Nd3+ activated strontium barium niobate laser crystal

Tunable laser action from a diode pumped Nd³⁺ activated Sr_xBa_1-x(NbO₃)₂ crystal has been obtained. A wide continuous tuning range of 43 nm in the near infrared region (1050–1093 nm) has been demonstrated due to the broad ⁴F_3/2→⁴I_11/2 emission band present in this system. Simultaneously, 20 nm of tunability in the green region (525–545 nm), as well as 7 nm in the blue one (455–462 nm) have been achieved by tunable self-frequency conversion processes using the quasiphase matching technique, without any angle or thermal tuning of the laser crystal. The results evidence that the system is a reliable candidate for compact tunable coherent devices based on diode pumped Nd³⁺ active ions, which are of interest in many technological and scientific applications. PACS 77.84.Dy; 42.79.Nv; 42.60.Fc; 42.55. Xi     

Non-hazardous synthesis of isocephosphorin intermediates via α-vinylamino-β-lactams

The reaction of a Schiff Base derived from veratrylamine and cinnamaldehyde with (α-methyl-β-alkoxycarbonyl)-vinylamino acetic acid (from glycine and an acetoacetate ester) in presence of a chloroformate ester and triethylamine constitutes a safe synthesis of α-vinylamino β-lactams that can be converted by literature methods to known intermediates for the synthesis of isocephalosporins and analogs.     

n -Heptane and methylcyclohexane transformation over a HMCM-22 zeolite. Origin of the features typical of large-or of medium-pore zeolites

The main features of methylcyclohexane (mch) and n-heptane (n-C₇) transformation at 350°C were compared for fresh samples of HMWW, HMFI and HFAU zeolites. With both reactions, the behavior of HMWW was between those of the medium HMFI and large pore HFAU zeolites. Thus, the values of turnover frequency (TOF) and of the TOF_mch/n-C7 ratio were similar with HMWW and HMFI and much higher with HFAU. In contrast, small differences were found between product distributions over HMWW and HFAU but large differences between HMWW and HMFI. These observations can be explained by alkane transformation in the large supercages with 10-MR apertures of HMWW: the narrow apertures limit diffusion of the mch within the supercages, but not the diffusion of the products which are therefore typical of the transformation within large cages hence without any steric limitation.     

Capillary zone electrophoretic determination of cytochrome c in mitochondrial extracts and cytosolic fractions: Application to a digitalis intoxication study

We describe a capillary zone electrophoretic procedure with photodiode-array detection for the determination of the apoptogenic protein cytochrome c in cytosolic fractions and mitochondrial extracts from guinea pig hearts. Optimal separation was achieved with a 100mM phosphates electrolyte solution at pH 2.05. The applied voltage was 25kV and the capillary temperature was kept constant at 25+/-0.5 degrees C. The method was linear over the concentration range of 0.2-600pM. All determination coefficients were higher or equal to 0.9989. Limits of detection and quantitation were 0.06pM (S/N=3) and 0.21pM (S/N=10), respectively. The present method offers a time-saving way to determine cytochrome c since it can be completed in 12min, compared to a time scale of days for Western blotting methods, or hours for ELISA-based methods. The procedure is illustrated by experiments that quantify cytochrome c released under control conditions and in a digitalis intoxication experimental animal model, in which cytochrome c content was successfully determined and was found to be (mean+/-standard deviation): control cytosol (0.48+/-0.01pM), digitalis-intoxicated cytosol (0.85+/-0.01pM), control mitochondria (1.11+/-0.1pM) and digitalis-intoxicated mitochondria (0.75+/-0.02pM). Recovery results ranged from 98.4 to 110.2%. Hence, the proposed analytical method could be useful to elucidate the digitalis intoxication mechanism as well as the role of cytochrome c in mediating apoptosis.     

Squaraines as reporter units: insights into their photophysics, protonation, and metal-ion coordination behaviour

The synthesis, photophysical properties, protonation, and metal-ion coordination features of a family of nine aniline-based symmetrical squaraine derivatives are reported. The squaraine scaffold displays very attractive photophysical properties for a signalling unit. These dyes show absorption and weakly Stokes-shifted, mirror-image-shaped emission bands in the visible spectral range and there are no hints of multiple emission bands. The mono-exponential fluorescence decay kinetics observed for all the derivatives indicate that only one excited state is involved in the emission. These data stress the interpretation that squaraines can be regarded as polymethine-type dyes. From a coordination chemistry point of view, the squaraines possess four potential binding sites; that is, two nitrogen atoms from the anilino groups and two oxygen atoms from the central C(4)O(2) four-membered ring. These coordination sites are part of a cross-conjugated pi-system and coordination events with protons or certain metal ions affect the electronic properties of the delocalised pi-system dramatically, resulting in a rich modulation of the colour of the squaraines. The absorption band at around 640 nm is blue-shifted when coordination at the anilino nitrogen atoms occurs, whereas coordination to the C(2)O(4) oxygen atoms results in the development of red-shifted bands. Addition of more than one equivalent of protons or metal cations could additionally entail mixed N,O- or N,N-coordinated complexes, manifested in the development of a broad band at 480 nm or complete bleaching in the visible range, respectively. Analysis of the spectrophotometric titration data with HYPERQUAD yielded the macroscopic and microscopic stability constants of the complexes. Theoretical modelling of the various protonated species by molecular mechanics methods and consideration of some of the title dyes within the framework of molecular chemosensing and molecular-scale "logic gates" complement this contribution.