Synthesis of macrocyclic antibiotics. 10. Synthesis of the C9−C13 fragment of neomethinolide

Conclusions The C⁹–C¹³ fragment of neomethinolide has been synthesized from D-xylose.For communication 9, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2571–2575, November, 1986.     

Synthesis of macrolide antibiotics. 18. Stereospecific building up of the carbon chain of erythronolide B

Conclusions A stereodirected synthesis of erythronolide B carbon chain was carried out starting from from levoglucosan.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 688–693, March, 1989.     

Photocatalytic lithography with image inversion

The feasibility of the inversion of metal images obtained by the chemical deposition of nickel onto Pd²⁺-loaded films of nanostructural TiO₂ exposed to high irradiation doses has been demonstrated. This permits the generation of both negative and positive metallic pictures by varying the irradiation dose, which expands the scope for obtaining planar metallic elements with complex structural organization. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 45, No. 1, pp. 32–35, January–February, 2009.     

Nanoscale ZnCdS/ZnSSe heterostructures for semiconductor lasers

We investigated cathode luminescence of ZnCdS/ZnSSe heterostructures and structures with quantum wells (QW) grown by vapor phase epitaxy from metalloorganic compounds depending on the excitation level, composition, and thickness of the ZnCdS layer. The observed dependences are explained by specific features of the energy band diagram of heterostructures with gaps in type II bands and composition nonuniformity over the ZnCdS layer thickness. A 478-nm laser with transverse optical pumping by N₂-laser was realized at T = 80 K on the ZnCdS/ZnS/ZnSSe structure with QW.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Kinetics of structural relaxation of bulk and ribbon Pd<Subscript>40</Subscript>Cu<Subscript>30</Subscript>Ni<Subscript>10</Subscript>P<Subscript>20</Subscript> glasses determined from electrical resistance measurements

The electrical resistances of ribbon and bulk Pd₄₀Cu₃₀Ni₁₀P₂₀ metallic glasses, whose quenching rates differ by four orders of magnitude, were precisely measured during cyclic heating. Three stages of electrical resistance relaxation are detected as the maximum heating temperature increases. The first and third stages decrease the electrical resistance, and the second stage increases it. The first stage is shown to be caused by the relaxation of deformation-induced internal stresses and not to be related to the excess free volume concentration, which differs by a factor of about 2 in the ribbon and bulk samples. The second stage reflects structural relaxation in the glass and is only partly related to its free volume. The third relaxation stage is assumed to be caused by fine precrystallization phenomena like phase separation. The effect of deformation by rolling or quenching from the temperature range of a supercooled melt on the resistance relaxation kinetics was also studied.