Use of the Frank sequence in pulsed EPR

The Frank polyphase sequence has been applied to pulsed EPR of triarylmethyl radicals at 256 MHz (9.1 mT magnetic field), using 256 phase pulses. In EPR, as in NMR, use of a Frank sequence of phase steps permits pulsed FID signal acquisition with very low power microwave/RF pulses (ca. 1.5 mW in the application reported here) relative to standard pulsed EPR. A 0.2 mM aqueous solution of a triarylmethyl radical was studied using a 16 mm diameter cross loop resonator to isolate the EPR signal detection system from the incident pulses

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

Наведено результати розробки емпіричних рівнянь для розрахунку параметрів рівноваги газ-рідина в системі NH3 – CO2 – H2O за тиску нижче атмосферного і концентраціях NH3 і CO2 в рідини в діапазоні їх розчинності в воді. Зокрема, отримано формули для розрахунку рівноважного тиску аміаку, діоксиду вуглецю і водяної пари, а також температури кипіння розчину під атмосферним тиском.The article presents the results of development of empirical equations for calculation of the gas-liquid equilibria parameters of the system NH3 - CO2 - H2O at a pressure below atmospheric and NH3 and CO2 concentrations in the liquid in the range of their solubility in water. The formulas for calculating of ammonia, carbon dioxide and water vapour equilibrium pressure, and their solution boiling point at atmospheric pressure were obtained.Приведены результаты разработки эмпирических уравнений для расчета параметров равновесия газ-жидкость в системе NH3 – CO2 – H2O при давлениях ниже атмосферного и концентрациях NH3 и CO2 в жидкости в диапазоне их растворимости в воде. В частности, получены формулы для расчета равновесного давления аммиака, диоксида углерода и водяного пара, а также температуры кипения раствора под атмосферным давлением

Covariant Action for a D=11 Five-Brane with the Chiral Field

We propose a complete Born-Infeld-like action for a bosonic 5-brane with the worldvolume chiral field in a background of gravitational and antisymmetric gauge fields of D=11 supergravity. When the five-brane couples to a three-rank antisymmetric gauge field local worldvolume symmetries of the five-brane require the addition to the action of an appropriate Wess-Zumino term. To preserve general coordinate and Lorentz invariance of the model we introduce a single auxiliary scalar field. The auxiliary field can be eliminated by gauge fixing a corresponding local symmetry at the price of the loss of manifest d=6 worldvolume covariance. The double dimensional reduction of the five-brane model results in the Born-Infeld action with the Wess-Zumino term for a D=10 four-D-brane.Comment: LaTeX file, 10 pages, the form of eq. (8) corrected, a Comment added, version to appear in Phys. Lett.

In situ laccase-assisted overdyeing of denim using flavonoids

A laccase-mediated system for denim overdyeing using phenolic compounds was developed. Laccase from ascomycete Myceliophthora thermophila was able to oxidize phenolic compounds such as catechol and catechin and mediate their attachment to denim surfaces. Laccase-generated polymers gave rise to new coloration states from dark brown to green–yellow and replaced dyes in the overdyeing process. Process parameters, such as enzyme dosage, incubation time and presence of mediator, were studied by considering a compromise between the highest overdyeing level and lower energy/products consumption (2 U/mL laccase; 4 h incubation in the absence of mediator). Enzyme-generated polymers were followed by UV/Vis spectrophotometry and their level of attachment to denim surfaces was evaluated by means of spectral values quantification [k/s, Kubelka–Munk relationship (k=absorption coefficient, s=scattering coefficient)]. Overdyeing of denim with phenolics, such as catechol or catechin, was successfully achieved with acceptable levels in terms of durability.S.Y.K. would like to acknowledge the BIORENEW European Project - Sixth Framework European Program. C.S. would like to acknowledge the Portuguese Fundacao para a Ciencia e a Tecnologia (FCT) for funding under the scholarship SFRH/BPD/46515/2008

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

Learning from Crowds with Crowd-Kit

This paper presents Crowd-Kit, a general-purpose computational quality control toolkit for crowdsourcing. Crowd-Kit provides efficient and convenient implementations of popular quality control algorithms in Python, including methods for truth inference, deep learning from crowds, and data quality estimation. Our toolkit supports multiple modalities of answers and provides dataset loaders and example notebooks for faster prototyping. We extensively evaluated our toolkit on several datasets of different natures, enabling benchmarking computational quality control methods in a uniform, systematic, and reproducible way using the same codebase. We release our code and data under the Apache License 2.0 at https://github.com/Toloka/crowd-kit.Comment: published at JOS

A STUDY OF THE FLOCCULS STRENGTH OF POLYDISPERSE COAL SUSPENSIONS TO MECHANICAL INFLUENCES

The effect of the concentration and disperse composition on the flocculation strength to mechanical influence is investigated. It is found that the residual rate of floccules sedimentation after the mechanical influence at a constant rate of flocculant has a maximum value at a concentration of solids in the slime in the range of 7-30 g/dm3. The best results are obtained in all the experiments at a solids concentration of 10 g/l. It is found that at a concentration up to 7 g/l and more than 30 g/l, the floccules is formed. They have the lowest residual rate after mechanical influences. With increasing content of the solid fraction of 40-100 microns over 15%, the strength of floccules increases. They retain their shape and relatively high sedimentation rate even after mechanical influence. The obtained data allow to recommend correction of the slime composition before flocculant injection both the concentration close to the optimum, and the content of size fraction of 40-100 mm more than 15 %

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

OPTIMIZATION OF FLOCCULAR CLEANING AND DRAINAGE OF THIN DISPERSED SLUDGES

The efficiency of solid phase retention and dehydration of finely dispersed products of a coal processing plant and a metallurgical enterprise on the module for cleaning and dewatering sludge is investigated. A technique for selecting the operating parameters of equipment based on the determination of the strength criterion of flocs is proposed. A methodology for technological tests has been developed to control the flocculation process and optimize the flow of flocculant depending on the concentration of the solid phase. Industrial tests on the module for wastewater treatment and sludge dewatering using flocculants proved the effectiveness of the developed methodology. It is shown that the conditions for conducting tests on flocculation should correspond to the operating conditions of the circuit apparatus for cleaning and dewatering sludge. These conditions include sludge performance, sludge flow rate in the cross section of pipes and apparatuses, and the flow time from the flocculator to the centrifuge. During the testing of the Module, the solids retention efficiency of 97–99 % was achieved with the strength criteria of flocs in front of a centrifuge of 2–2.5 mm/s. The conditions for the high efficiency of the apparatus chain are the optimization of the aggregation process itself. It is revealed that for the formation of strong flocs it is necessary to regulate the concentration of the solid phase. For coal sludge, the concentration of the solid phase before the flocculant is fed must be maintained no higher than 50–60 g/l, and for gas treatment sludge – no higher than 20–25 g/l. Correction of the concentration of sludge before the flocculator is possible by diluting it with clarified water to the optimum concentration for aggregation. It is found that the moisture content of the sediment and the efficiency of the retention of the solid phase depend on the strength criterion of the flocs. Therefore, the optimization of the flocculant flow rate is possible by controlling and the residual floccule deposition rate after mechanical action in front of the dewatering equipment. The flocculant flow rate must be adjusted depending on the concentration of the solid phase in the sludge to achieve the desired criterion for the strength of the floc

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