Ionic liquids (IL) based on tetrahexyl-, tetraheptyl-, and tetraoctylammonium cations and dicyanamide anion were obtained as a result of the chemical interaction of ammonium bromides with dicyanamide salts. The purity of IL synthesized (>98%) was confirmed by atomic absorption spectrometry and ionic chromatography. The influence of such factors as solution acidity, extraction, temperature, and duration, the ratio of organic and aqueous phase volumes on the recovery of platinum ions was studied. It was shown, that ionic liquids with longer alkyl chains exhibit higher efficiency due to their improved hydrophobic properties. Spectroscopic analysis of the extracted systems revealed that the mechanism of platinum extraction is associated with the formation of stable ion pairs between metal halogen complexes and tetraalkylammonium cations. This interaction causes a hypsochromic shift in the absorption spectra (λ max = 261 nm), confirming the nature of the formed compounds. Ionic liquids demonstrated stability and low solubility in the aqueous phase, which makes them reliable extractants. The application of the proposed eco-friendly approach can be useful for recycling secondary platinum sources, cleaning industrial wastewater and minimizing environmental pollution.
The growing demand for clean-label plant-based cheese alternatives underscores the need for products with desirable properties. A key technological challenge is replicating the firmness of traditional cheese without synthetic additives. This study explores lactic acid bacteria (LAB) fermentation as a natural texturizing method for clean-label plant-based cheeses. We investigated the link between LAB metabolic traits and the firmness of three substrates: cashew, soybean, and sunflower seed. A strong correlation (r ≈ −0.88) was found between final pH and firmness in cashew paste, where strains achieving a pH of ~4.0–4.5 (near the protein isoelectric point) produced the firmest gels (up to 3.35 N). Lactiplantibacillus plantarum 729/23 and Lacticaseibacillus helveticus NK-1 were most effective. Soybean paste firmness increased moderately (to 1.93 N), while sunflower seed paste showed no significant improvement (≤1.14 N) despite active acidification, indicating substrate-specific limitations. This study, supported by a comprehensive analysis of the literature on firmness measurement in plant-based cheeses, demonstrates the potential of targeted selection of natural starter cultures to create clean-label products with minimal ingredients.
The paper considers the development of a web application for managing software projects, which is designed for planning, assigning and tracking tasks, monitoring the completion of stages, delimiting access rights, organizing teamwork and promptly notifying participants. Special attention is paid to the issues of protecting the application from cyber threats.
The problem is solved in analytical form using the method of universal fast expansions. The obtained approximate analytical solution is compared with the test one, the error in determining the plate deflection is investigated. It is found that when using a sixth-order boundary function and only one term in the cosines and one term in the sines in the Fourier series in universal fast expansions, the accuracy of the obtained solution significantly exceeds the accuracy of specifying the input parameters of the problem determined by the concept of a continuous medium. In this case, the approximate analytical solution can formally be considered exact.
В статье представлена принципиально новая математическая модель, описывающая динамику процесса ультразвуковой экстракции экстрактивных веществ из дубовой щепы в водно-спиртовой среде. Основная цель работы заключалась в создании модели, которая явно и количественно учитывала бы влияние интенсивности ультразвука и температуры. Модель построена на основе законов химической кинетики гетерогенных процессов, что отличает ее от классических диффузионных и эмпирических подходов и позволяет описать процесс экстракции по аналогии с реакцией первого порядка. Такой подход обеспечивает связь скорости процесса с его физико-химической природой. Преобразование исходного кинетического уравнения с учетом материального баланса в системе «дубовая щепа — раствор» обеспечило адекватность и удобную для расчетов форму модели, связывающую концентрацию экстракта в жидкости со временем, температурой и интенсивностью ультразвука. Для определения параметров модели и проверки адекватности были специально проведены экспериментальные исследования. Эксперименты выполняли при варьировании интенсивности ультразвука в диапазоне от 1,5 до 5,0 Вт/см² и температуры в диапазоне от 25 до 45 °C. На основе анализа полученных кинетических кривых были определены ключевые параметры модели: эмпирическая зависимость равновесной концентрации экстракта как от интенсивности ультразвука, так и от температуры; степенная зависимость предэкспоненциального множителя от интенсивности ультразвука; а также установлено постоянное значение эффективной энергии активации процесса. Окончательная модель представлена в виде аналитического выражения, в которое в явном виде входят время, температура и интенсивность ультразвука. Статистическая проверка модели подтвердила ее высокую точность: максимальная относительная погрешность не превышает 4,7%. Разработанная модель представляется эффективным инструментом для количественного прогнозирования и служит научной основой для оптимизации режимов ускоренного созревания дистиллятов. This article presents a fundamentally new mathematical model describing the dynamics of the ultrasonic extraction of extractive substances from oak chips in a water-alcohol medium. The primary objective of the study was to create a model that explicitly and quantitatively accounts for the effects of ultrasound intensity and temperature. The model is based on the laws of chemical kinetics of heterogeneous processes, which distinguishes it from classical diffusion and empirical approaches and allows for the extraction process to be described by analogy with a first-order reaction. This approach links the process rate with its physicochemical nature. Transforming the original kinetic equation, taking into account the material balance in the oak chips-solution system, ensured the adequacy and calculation-friendly form of the model, linking the extract concentration in the liquid with time, temperature, and ultrasound intensity. Experimental studies were conducted to determine the model parameters and verify its adequacy. Experiments were conducted with ultrasound intensity varying from 1.5 to 5.0 W/cm² and temperature ranging from 25 to 45 °C. Based on an analysis of the obtained kinetic curves, key model parameters were determined: the empirical dependence of the equilibrium extract concentration on both ultrasound intensity and temperature; the power-law dependence of the pre-exponential factor on ultrasound intensity; and the establishment of a constant value for the effective activation energy of the process. The final model is presented as an analytical expression that explicitly incorporates time, temperature, and ultrasound intensity. Statistical verification of the model confirmed its high accuracy: the maximum relative error does not exceed 4.7%. The developed model is an effective tool for quantitative forecasting and serves as a scientific basis for optimizing accelerated distillate maturation modes.
