Accessibility of hydroxy groups of pectin substances for deuteration

An apparatus for the deuteration of solid samples and for recording their IR spectra in a current of D₂O vapor, and an IR-spectroscopic method of determining the degree of deuteration (q) of the hydroxy groups of pectin substances (PSs) are described. It has been established that there are no zones of structurally different nature in films of derivatives of PSs at the carboxy group. The rate of deuterium-exchange of the water of hydration of PSs is higher than for the hydroxy groups of the pyranose rings. The rate of deuterium exchange depends on the density of packing of the polymer chains of the pectin derivatives.Center for the Automation of Scientific Investigations and Metrology, Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Khimiya Priorodnykh Soedinenii, No. 3, pp. 343–348, May–June, 1987.     

Researches on synthetic dyes

Reaction of phenyl-ß-naphthylamines with formaldehyde and acetone in the presence of HCl and nitrobenzene in butanol solution leads to cyclization involving the naphthalene and phenyl rings, and formation of N-aryllepidine salts. 15 lepidine and 5, 6-benzoepidine salts are synthesized and characterized by their UV absorption spectra, as well as by their picrates.For Part LIII see [3].     

Structure,tautomerism, and transformations of β-(3-nitro-2-pyridyl)- and β-(3-nitro-4-pyridyl)pyruvic acid esters

It was shown by means of IR, UV, and PMR spectra that -(3-nitro-2-pyridyl)pyruvic acid esters are practically completely enolized in the crystal state and in solution; ethyl -(3-nitro-4-pyridyl)pyruvate has an enol structure in the crystalline state and in pyridine solution but exists as a mixture of keto and enol forms in low-polarity solvents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 389–393, March, 1974.     

Gas-discharge plasma initiated in air by a radiation pulse

Formation of a nonequilibriuin gas-discharge plasma in air under the action of radiation at a wavelength of 10.6 with a duration of 10^–6 sec is considered. It is shown that the air discharge occurs under nonequilibrium conditions by formation of an autoionization complex with subsequent oscillatory excitation of molecules. The molecular distribution function over oscillatory degrees of freedom is found in the diffusion approximation. The electron temperature and concentration in the breakdown plasma are calculated with consideration of multistep ionization of molecules and dissociative recombination of charged particles. Results are compared with experiment.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 9–13, February, 1985.     

Trigonometric polynomials with many real zeros

This is a contribution to the theory of “incomplete trigonometric polynomials”T _n , but mainly for the case when their zeros are not concentrated at just one point, but are distributed in some intervalI whose length is not too large. We begin with the simple theorem that if ∥T _n ∥ ≤ 1 and ifT _n has ≥θn, 0<θ< 2, zeros at 0, thenT _n (t) must be small on the interval |t|<2 arcsin (θ/2). There are similar but more complicated and more difficult to prove results whenT _n has ≥θn zeros onI. These results have the following application: IfT _n →f a.e., and if ∥T _n >∥_∞<-1, thenf vanishes on a set of the circleT whose measure is controlled by lim sup (N _n /n), whereN _n is the number of zeros ofT _n onT. In turn, this has further applications to series of polynomials, to norms of Lagrange operators, and to Hardy classes.     

Validated ion-exclusion chromatographic method for citrate and acetate in medical fluids

In this paper we describe the development and validation of a solid-phase extraction procedure, followed by ion-exclusion chromatographic determination of citrate and acetate in medical fluids. The medical fluids contained trace levels of non-polar compounds, which were not of interest for the purposes of assay requirements, but due to their strong affinity towards the ion-exclusion chromatography column necessitated a 180-min long runtime to elute. The developed SPE procedure, based on trapping the hydrophobic compounds, on a reversed-phase material, while allowing analytes of interest elute off unretained, shortened the runtime to 35 min. The procedure is simple since it has only two steps, conditioning of the SPE cartridge with acetonitrile and treating the sample. The SPE procedure followed by ion-exclusion chromatographic determination was successfully validated per the International Conference on Harmonization (ICH) guidelines in terms of specificity, accuracy as recovery versus untreated sample, precision, range, linearity of response, ruggedness, stability of treated samples, and robustness. The validation data showed that the method is specific, accurate, precise, rugged, and robust. The validated method has been routinely used in the manufacturing environment.