New heterocycles from 8‐hydroxyquinoline via dipolar 1,3‐cycloadditions: Synthesis & biological evaluation

Diarylnitrilimine and arylnitriloxide dipoles react with two 8‐hydroxyquinoline substrates to give respectively pyrazolinic and isoxazolinic derivatives. The structure of these new heterocycles was established on the basis of their spectroscopic data and by chemical methods. The inhibition activity of one of these heterocycles was evaluated in vitro against 8 pathogenic μ‐organisms.     

Thienamycin. A solution of the stereochemical problem

A new nitrone-based synthesis of β-lactams is described which makes provision for the 1-hydroxyethyl moiety in the potent antibiotic thienamycin. Moreover, the relative stereochemical features of the natural product are defined in a step involving the cycloaddition of a nitrone with methyl crotonate.     

Acetylenic β-keto Ester of Th(IV), U(IV), and U(VI) Compounds

Acetylenic β-keto ester (L) compounds ML₄ (M = Th and U), and UO₂L₂ · EtOH have been prepared by reactions in non-aqueous solvents. The infrared spectra of these compounds are reported together with some of their chemical properties.     

Linear filtering of speckled images

Linear minimum mean square error filters are determined for restoration of images distorted by speckle. Dependence of the performance of the system on the statistical parameters of the speckle's inherent phase fluctuation is assessed.     

Two dimensional image scanning of movies using surface acousto-optic interaction

The scanning of two-dimensional black and white movies is described by using the interaction of light with surface acoustic waves. The modulation transfer function for the image scanner is derived. Further, it is shown that the spatial resolution is limited by the surface acoustic wave transducer bandwidth rather than the physical size of the exit pupil of the scanner.     

Entanglement in cascaded-crystal parametric down-conversion

We use spontaneous parametric down-conversion in a cascade of crystals, driven by a single monochromatic cw pump laser, to study the interference of entangled photon pairs. By changing the distance between the crystals, the observed quantum interference pattern varies continuously from that associated with a longer single crystal to that associated with independent emissions from two distinct crystals. Postselection via spectral filtering suppresses this phenomenon. These findings are expected to advance the field of quantum-state engineering.     

Determination of trimetazidine dihydrochloride in the presence of its acid-induced degradation products

Three methods are presented for the determination of trimetazidine dihydrochloride in the presence of its acid-induced degradation products. The first method was based on measurement of first-derivative D1 value of trimetazidine dihydrochloride at 282 nm over a concentration range of 8.00-56.00 microg/mL with mean percentage accuracy of 99.80+/-1.17. The second method was based on first derivative of the ratio spectra DD1 at 282 nm over the same concentration range with the percentage accuracy of 99.14+/-0.68. The third method was based on separation of trimetazidine dihydrochloride from its acid-induced degradation products followed by densitometric measurement of the spots at 215 nm. The separation was performed on silica gel 60 F254 using methanol-ammonia (100+/-1.5, v/v) as mobile phase. This method was applicable for determination of the intact drug in the presence of its degradation products over a concentration range of 2.00-9.00 microg/spot with mean percentage accuracy of 99.86+/-0.92. The proposed methods were successfully applied for the determination of trimetazidine dihydrochloride in bulk powder, laboratory-prepared mixtures containing different percentages of degradation products, and pharmaceutical dosage forms. The validity of results was assessed by applying the standard addition technique. The results obtained agreed statistically with those obtained by the reported method.