Dielectric Response and a Phenomenon of a Narrow Band Absorption for a Classical Rotor in a Double Well Potential

The theory of dielectric relaxation in a planar ensemble of polar molecules is presented for a model where dipoles rotate in an intermolecular conservative double well potential, having a profile U = U_0*sin^2(θ). The evolution of the wide band dielectric spectra is demonstrated when the potential depth U_0 is varied; an isotropic and anisotropic medium being taken as examples. The spectra comprise the Debye relaxation and the quasi-resonant Poley absorption region. The rigorous theory is compared with a simplified one which was called the hybrid quasi-elastic bond / extended diffusion model. This approximation is valid for a qualitative description and also for the quantitative one at the large field parameter p = (U_0/((k_B)T))^(1/2). For P >> 1 the spectrum comprises one narrow absorption band and one Debye relaxation region considerably shifted to low frequencies. It is show that in the long lifetime limit τ there exists a minimum absorption band Δν_0(p). The quantity Δν_0 becomes small if the parameter p >> 1.The dielectric relaxation in ice 1 is discussed with regards to this phenomenon

HYDROLYTIC STABILITY OF IMIDES OF DIFFERENT STRUCTURES

The conversion kinetics of N(o-carboxyphenyl)naphthalimide has been studied in buffer solutions over a pH range 5-12.6 and temperature range 25-70 °C. The naphthalimide hydrolysis is shown to be a reversible reaction. The mechanism of the alkaline hydrolysis of N(o- carboxyphenyl) phthalimide is proposed. The structure dependence of the imide hydrolytic stability is explained on the basis of the suggested mechanism

Четверта міжнародна наукова-практична конференція «Комп’ютерне моделювання в хімії і технологіях та системах сталого розвитку»

Розглянуто розрахунок рівноважного складу розчину в системі сульфід – гідросульфід барію – сірководень – вода. Запропонована система рівнянь, яка з високою достовірністю описує зміну рН в залежності від відношення загальних концентрацій барію та сірки у розчині, що, зокрема, може бути використано при визначенні швидкості абсорбції діоксиду вуглецю.The article considers calculating the equilibrium composition of the solution in the barium sulphide / barium hydrosulphide / hydrogen sulphide / water system. It proposes a system of equations that reliably describes the pH change as a function of the barium to sulphur total concentration ratio in the solution. These equations can be particularly useful in calculating the rate of absorption of carbon dioxide.Рассмотрен расчет равновесного состава раствора в системе сульфид – гидросульфид бария – сероводород – вода. Предложена система уравнений, которая с высокой достоверностью описывает изменение рН в зависимости от отношения общих концентраций бария и серы в растворе, что, в частности, может быть использовано для расчета скорости абсорбции диоксида углерода

Rapid-Scan EPR of Immobilized Nitroxides

X-band electron paramagnetic resonance spectra of immobilized nitroxides were obtained by rapid scan at 293 K. Scan widths were 155 G with 13.4 kHz scan frequency for 14N-perdeuterated tempone and for T4 lysozyme doubly spin labeled with an iodoacetamide spirocyclohexyl nitroxide and 100 G with 20.9 kHz scan frequency for 15N-perdeuterated tempone. These wide scans were made possible by modifications to our rapid-scan driver, scan coils made of Litz wire, and the placement of highly conducting aluminum plates on the poles of a Bruker 10 magnet to reduce resistive losses in the magnet pole faces. For the same data acquisition time, the signal-to-noise for the rapid-scan absorption spectra was about an order of magnitude higher than for continuous wave first-derivative spectra recorded with modulation amplitudes that do not broaden the lineshapes

Rapid-Scan EPR of Immobilized Nitroxides

X-band electron paramagnetic resonance spectra of immobilized nitroxides were obtained by rapid scan at 293 K. Scan widths were 155 G with 13.4 kHz scan frequency for 14N-perdeuterated tempone and for T4 lysozyme doubly spin labeled with an iodoacetamide spirocyclohexyl nitroxide and 100 G with 20.9 kHz scan frequency for 15N-perdeuterated tempone. These wide scans were made possible by modifications to our rapid-scan driver, scan coils made of Litz wire, and the placement of highly conducting aluminum plates on the poles of a Bruker 10 magnet to reduce resistive losses in the magnet pole faces. For the same data acquisition time, the signal-to-noise for the rapid-scan absorption spectra was about an order of magnitude higher than for continuous wave first-derivative spectra recorded with modulation amplitudes that do not broaden the lineshapes

ФОРМИРОВАНИЕ «НОВОЙ БИФУРКАЦИИ» У БОЛЬНЫХ С ПРОЛОНГИРОВАННЫМ АТЕРОСКЛЕРОТИЧЕСКИМ ПОРАЖЕНИЕМ ВСА

This article provides indications for and description of surgical technique of carotid endarterectomy with the formation of a new bifurcation. It also presents the results of observations in the immediate postoperative period based on the findings of this surgery among patients of Vishnevsky National Medical Research Center of Surgery.В данной статье приведены показания для проведения и подробная техника выполнения КЭАЭ с формированием новой бифуркации. Также приведены результаты наблюдений в ближайшем послеоперационном периоде по результатам этой операции среди пациентов института хирургии им. А. В. Вишневского