A ray mode parabolic equation for shallow water acoustics propagation problems

Ray mode parabolic equations which are suitable for shallow water acoustics propagation problems are derived by the multiple-scale method.Comment: 7 pp., 0 fi

Instantaneous Radio Spectra of Giant Pulses from the Crab Pulsar from Decimeter to Decameter Wavelengths

The results of simultaneous multifrequency observations of giant radio pulses from the Crab pulsar, PSR B0531+21, at 23, 111, and 600 MHz are presented and analyzed. Giant pulses were detected at a frequency as low as 23 MHz for the first time. Of the 45 giant pulses detected at 23 MHz, 12 were identified with counterparts observed simultaneously at 600 MHz. Of the 128 giant pulses detected at 111 MHz, 21 were identified with counterparts observed simultaneously at 600 MHz. The spectral indices for the power-law frequency dependence of the giant-pulse energies are from -3.1 to -1.6. The mean spectral index is -2.7 +/- 0.1 and is the same for both frequency combinations (600-111 MHz and 600-23 MHz). The large scatter in the spectral indices of the individual pulses and the large number of unidentified giant pulses suggest that the spectra of the individual giant pulses do not actually follow a simple power law. The observed shapes of the giant pulses at all three frequencies are determined by scattering on interstellar plasma irregularities. The scatter broadening of the pulses and its frequency dependence were determined as tau_sc=20*(f/100)^(-3.5 +/- 0.1) ms, where the frequency f is in MHz.Comment: 13 pages, 1 figure, 1 table (originally published in Russian in Astronomicheskii Zhurnal, 2006, vol. 83, No. 7, pp. 630-637), translated by Georgii Rudnitski

Rapid Mass Spectrometric Study of a Supercritical CO2-extract from Woody Liana Schisandra chinensis by HPLC-SPD-ESI-MS/MS

Woody liana Schisandra chinensis contains valuable lignans, which are phenylpropanoids with valuable biological activity. Among green and selective extraction methods, supercritical carbon dioxide (SC-CO2) was shown to be the method of choice for the recovery of these naturally occurring compounds. Carbon dioxide (CO2) was the solvent with the flow rate (10−25 g/min) with 2% ethanol as co-solvent. In this piece of work operative parameters and working conditions were optimized by experimenting with different pressures (200–400 bars) and temperatures (40–60 °C). The extraction time varied from 60 to 120 min. HPLC-SPD-ESI -MS/MS techniques were applied to detect target analytes. Twenty-six different lignans were identified in the S. chinensis SC-CO2 extracts

ИНДИВИДУАЛЬНЫЕ ОСОБЕННОСТИ КРОВОСНАБЖЕНИЯ И ЛАТЕРАЛЬНОЕ МЕТАСТАЗИРОВАНИЕ РАКА ПРЯМОЙ КИШКИ

One of the main causes of local recurrence of rectal cancer is the regional lymphatic nodes metastasis. Existing methods of staging does not have absolute sensitivity and specificity with regard to lesion of regional lymphatic nodes in general, and of lateral group in particular. It is necessary to look for new methods of diagnosis, to identify risk factors and unfavorable prognosis of lateral metastasis in colorectal cancer, which will provide a more differentiated approach to the choice of treatment policy, indications for neoadjuvant chemoradiotherapy and/or lymphatic node dissection. The work on the two groups of patients (control and basic) was performed on the basis of CT performed in angio mode and MRI investigated anatomical variability of middle rectal arteries, proved its impermanence, and studied the relationship between presence of the middle rectal artery and lesion of regional lymphatic nodes in rectal cancer. Prognostic risk factors for lateral metastasis in rectal cancer were proposed, comparative analysis techniques allowing for visualization of the middle rectal vessels was performed.Одной из основных причин местных рецидивов при раке прямой кишки является поражение регионарных лимфатических узлов. Существующие общепризнанные методы стадирования не обладают абсолютной чувствительностью и специфичностью в отношении поражения регионарных лимфатических узлов в целом и латеральной группы в частности. Имеется необходимость поиска новых методов диагностики, определения факторов риска и неблагоприятного прогноза латерального метастазирования при раке прямой кишки, что обеспечит более дифференцированный подход к выбору лечебной тактики, определению показаний к проведению неоадъювантной химиолучевой терапии и/или выполнению латеральной лимфодиссекции. В работе на двух группах пациентов (контрольной и основной) на основании данных компьютерной томографии, выполненной в ангиорежиме, и магнитно-резонансной томографии исследована анатомическая вариабельность средних прямокишечных артерий, доказано ее непостоянство, подробно изучены варианты отхождения. Установлена взаимосвязь между наличием средней прямокишечной артерии и поражением регионарных лимфатических узлов при раке прямой кишки. Предложены прогностические факторы риска развития латерального метастазирования при раке прямой кишки и проведен сравнительный анализ методик, позволяющих визуализировать средние прямокишечные сосуды

CATALYTIC PHOTOMETRIC DETERMINATION OF NITRATE IN NATURE WATER USING STEPWISE INJECTION ANALYSIS

A new express technique for the kinetic catalytic photometric determination of nitrate by stepwise injection analysis is introduced. The detection is based on the catalytic effect of nitrite on the oxidation of ethylendiaminetetreaacetat manganese (II) to red ethylendiaminetetreaacetat manganese (III) by hydrogen peroxide. Nitrate was preliminary reduced to nitrite using copperised cadmium reductor column. The measurement of the red color absorbance was monitored at 520 nm wavelength. Determined the reliable working concentration range to be 0.1 – 5 mg/dm3 with 3σ detection limit of 0.02 mg/dm3. The relative random measurement error of the technique does not exceed 15 %. The advantages and disadvantages of the copperised cadmium reductor location in the hydraulic circuits of the flow-injection and stepwise injection analysis methods were considered. Reviewed the copperised cadmium reductor placing using the stepwise injection analysis method presented in the literature and offered another alternative of placing. The proposed technique was tested by the added – found method and referent method with satisfactory results. The major advantages of this technique are simplicity, selectivity and economy of reagents. The technique can be used to automatically determine nitrate in continuous mode at a rate of 12 samples per hour, and in the mode with a delay between samples. The technique could be applied successfully for the nitrate determination in nature fresh and salt waters.Key words: nitrate, photometric determination, catalytic reaction, nature water, stepwise injection analysis(Russian)DOI:http://dx.doi.org/10.15826/analitika.2015.19.1.012 V.M. Zakharenko1, Iu.S. Khudiakov1, A.V. Mozzhukhin1, A.L. Moskvin21ZAO NPO Granit-NEMP, Saint Petersburg, Russian Federation2Saint Petersburg State University, Saint Petersburg, Russian Federatio