Box-Behnken assisted development and validation of high-performance liquid chromatography method for the simultaneous determination of doxorubicin and vorinostat in polymeric nanoparticles

While histone deacetylase inhibitors, such as vorinostat, demonstrate a significant effect against hematological cancers, their application for solid tumor treatment is limited. However, there is strong evidence that combinatorial administration of vorinostat and genotoxic agents (e.g., doxorubicin) enhances the antitumoral action of both drugs against tumors. We developed a high-performance liquid chromatography method for the simultaneous determination of doxorubicin and vorinostat in polymeric nanoparticles designed to provide the parenteral administration of both drugs and increase their safety profile. We performed separation on Nucleodur C-18 Gravity column with a mixture of 10 mM potassium dihydrogen phosphate buffer pH 3.9:ACN (90:10 v/v) as mobile phase at 240 nm. The method was linear within the concentration range of 4.2–52.0 μg/ml for both drugs with limits of detection and quantification of 3.5 and 10.7 μg/ml for doxorubicin and 2.5 and 7.7 μg/ml for vorinostat, respectively. The method was precise and accurate over the concentration range of analysis. Drug loading was 5.4% for doxorubicin and 0.8% for vorinostat. Degradation of doxorubicin after irradiation was less than 5%, while the amount of vorinostat decreased at 88% under the same conditions. Thus, the validated method could be adopted for routine simultaneous analysis of doxorubicin and vorinostat in polymeric nanoparticles.     

Lucigenin hexacyanoferrates

The reaction of lucigenin (Lc) with potassium hexacyanoferrate is accompanied by the appearance of charge-transfer bands in the visible spectral region and yields Lc{H}₂[Fe(CN)₆] · 4H₂O in an acidic medium and Lc₄[Fe(CN)₆](NO₃)₅ · 18H₂O in a neutral medium in air.     

Electrical resistivity and electron state density in binary iron alloys

An expression is derived for the phonon component of electrical resistivity using a four-band model which considers the electron contribution to conductivity from two 4s subbands and the hole contribution from two 3d subbands with differently oriented spins, using Mott's concepts in the relaxation time approximation. The expression obtained gives the dependence of resistivity upon electron state density at the Fermi level. The concentration dependence of resistivity is calculated for alloys of iron with chromium, manganese, cobalt, and nickel.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 7–12, April, 1979.     

Influence of Fermi surface topology on kinetic properties of Fe-Co alloys in the domain close to an equiatom composition

The electron energy spectrum for the superstructure FeCo is computed by a symmetrized Green's function method. A curve of the density of the electron states N() and the Fermi surface (FS) section is constructed for the ferromagnetic state obtained by a rigid shift in conformity with the value of the atomic magnetic moment of the alloy. A FS scheme is proposed, consisting of definite sheets belonging to different energy bands emerging at the Fermi level. A semiquantitative estimate is made of the magnitude of the FS area, and the contribution of separate FS sheets to the magnitude of the anomalous Hall R_s, Nernst-Ettingshausen Q_s and thermal emf S coefficients are examined. The nature of the change in the separate FS sections as the alloy composition changes is examined within the framework of the rigid band model, and a qualitative explanation is obtained for the concentration dependence of R_s and S in Fe-Co alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 3–9, December, 1981.     

Combustion of aluminum-magnesium alloy particles under microgravity conditions

The combustion of 200- to 600-μm single particles of 0.85 Al/0.15 Mg and 0.15 Al/0.85 Mg alloys in the CO₂ and O₂-N₂ (20: 80) media at pressures of 0.1 to 4.0 MPa is studied. The combustion occurred in a free-falling combustion chamber after ignition with a ruby laser. The specificity of the mechanism of the combustion of particles of these alloys is identified, and the combustion times of particles are determined. The character of this process (luminescence pulsations, fragmentation, etc.) is examined, and the solid combustion products are analyzed.     

Kinetics of Dissolution of Glassy Fertilizers

Slowly soluble phosphate glasses are a promising material for new environmentally safe fertilizers. The kinetics of the dissolution of phosphate glasses used for the development of fertilizers was studied.     

Measurement of form factors for the decay η′ å ηπ − π +

Form factors measured for the decay η′ å ηπ ^? π ⁺ in π ^? A å η′π ^? A* reactions at a beam momentum of p _π = 28 GeV are presented. The distribution in Dalitz variables for 7000 decay events is described well within a linear and a nonlinear parametrization of the relavant matrix element. The slope parameter in the variable y differs from zero significantly. It is Reα = ?0.072±0.012 (stat.)±0.006 (syst.) in the linear and a = ?0.120±0.027 (stat.)±0.015 (syst.) in the nonlinear parametrization. In this decay, the C-violation parameter is compatible with zero, c = 0.021±0.024.     

Ring currents and nuclear magnetic resonance in porphyrins

The McWeeny method [1] for calculating the -electron currents in aromatic molecules is modified for porphyrins. The distribution of the ring currents of the -electrons and their contributions to the chemical shifts of NH, -H, the meso protons, and the protons of the methyl groups of porphyrins with carbethoxy and methyl substituents in the form of dications and free bases are calculated. We show that the -electron current in the internal conjugation chain passing through the nitrogen atom decreases during the formation of the dication, while the total ring current increases by almost 10%. Introduction of an electron-accepting substituent in the -position intensifies the -electron current through the C—N bond of the corresponding pyrrole ring, and there is a simultaneous decrease in the total -electron current.