Application of chromatographic methods to the determination of cognac quality indicators

Gas and liquid chromatography methods were used to study 11 cognac samples; the analytical data were compared with the organoleptic control of the samples. The presence of triacetin and glycerol, an increased concentration of vanillin, and a high sucrose content should be considered as criteria for the possible adulteration of production.     

A functional model associated with a generalized Nevanlinna pair

Let $ \mathcal{L} $ be a Hilbert space, and let $ \mathcal{H} $ be a Pontryagin space. For every self-adjoint linear relation $ \tilde{A} $ in $ \mathcal{H} \oplus \mathcal{L} $ , the pair $ \{ I + \lambda \psi (\lambda ),\,\psi (\lambda )\} $ where $ \psi (\lambda ) $ is the compressed resolvent of $ \tilde{A} $ , is a normalized generalized Nevanlinna pair. Conversely, every normalized generalized Nevanlinna pair is shown to be associated with some self-adjoint linear relation $ \tilde{A} $ in the above sense. A functional model for this selfadjoint linear relation $ \tilde{A} $ is constructed.     

Self-assembly hexanuclear metallacontainer hosting halogenated guest species and sustaining structure of 3D coordination framework

Chloride-centered hexanuclear hydroxopyrazolate reveals potential as a receptor of halomethane and halometallate species and as a molecular building block for coordination polymers.     

Reversible and irreversible magnetic-field-induced changes in the plastic properties of NaCl crystals

It is established that a weak magnetic field with induction B∼1 T gives rise to irreversible changes in NaCl crystals without freshly introduced dislocations, while a strong magnetic field with induction 16<B<35 T gives rise predominantly to reversible changes. It is inferred that there exist two different channels whereby a magnetic field influences the state of point defects. Fiz. Tverd. Tela (St. Petersburg) 40, 2065–2068 (November 1998)     

Flow-injection determination of indole derivatives in pharmaceutical mixtures

The reactions of tryptamine derivatives with 4-chloro-5,7-dinitrobenzofurazan were studied. The composition of the products of analytical reactions was found from the data of elemental analysis, and their structures were confirmed by ¹H NMR spectra. The working conditions were selected for the flow-injection determination of 22 indole derivatives in pharmaceutical mixtures as 5,7-dinitrobenzofurazans with spectrophotometric detection at 490 nm. Optimum results were obtained using acetonitrile-buffer solution (pH 6.8) flows. The analytical range for biologically active substances was between 0.04 and 0.61 μg/mL. The throughput was 25–35 sample/h. The detection limit was 0.01 μg/mL. Serotonin, mexamine, melatonine, sumatryptan, and indolylacetic acid derivatives were determined in pharmaceuticals and in reaction mixtures from the synthesis of biologically active substances.     

Membrane switch hypothesis. 2. Domain structure of phagocytes in horses with recurrent airway obstruction

The mechanism of recurrent airway obstruction (RAO) in horses was investigated by measuring the membrane domain structure and oxy-redoxy activity in phagocytes isolated from bronchoalveolar lavage fluid (BAL) and from the blood of healthy and RAO horses by electron paramagnetic resonance (EPR). Differences in the activity of intracellular antioxidant enzymes CAT, GPx, and SOD measured in phagocytes of RAO horses in comparison to healthy horses showed that the phagocytes were affected by oxidative stress. In comparison with polymorphonuclear leukocytes (phagocytes) from the blood of healthy horses the reduction mechanisms in BAL were faster and coincided with the merging of disordered membrane domains, while in horses with RAO the reduction and membrane domain structure remained unchanged. We assume that the merging of lipid domains observed in phagocytes from BAL of healthy horses could promote cluster formation of membrane proteins or ligands, which could trigger the activation process in phagocytes of healthy horses and consequently the physiological response that probably did not happen in phagocytes of RAO horses.     

Correlation functions and power spectra of Doppler response signals in ultrasonic medical applications

Ultrasound Doppler methods are widely used in clinical practice as prospective investigational tool to study the vascular system and soft biological tissues. Meanwhile, the most general relationship between the power Doppler spectra, spectral characteristics of the scattering fluctuations and the probing ultrasound field parameters for some clinical implementations are still unexplored. Based upon the continuum model of scattering inhomogeneities, a set of the closed-form expressions for the correlation functions and the spectra of Doppler response of soft tissues and blood have been derived. The influence of the correlation among inhomogeneities and the diffusion processes on the Doppler power spectra formed by stationary flows have been examined. Computer simulations of Doppler spectra were performed for different values of correlation radius and diffusion coefficient. With simulation results the effects of the correlation among inhomogeneities and the diffusion processes on the spectral width and mean frequency are established and discussed in respect to turbulent flows. Closed-form expressions for correlation functions and Doppler spectra for the vibrational sonoelastography technique for visualizing malignant tumors in tissues have been derived. Based on the peculiarities of the obtained Doppler spectra, it is shown that the differentiation of soft tissues with respect to the amplitude value of constrained oscillations is feasible. The expressions were derived for the cases of non-stationary accelerated blood movement. It has been found that the frequency dependence reveals solely at a finite time of observation and depends on the initial phase of the accelerated movement.