Cu/cuo composite track-etched membranes for catalytic decomposition of nitrophenols and removal of as(III)

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Ministry of Education and Science of the Republic of Kazakhstan: AP05130797Funding: A.M. gratefully acknowledges the funding of the Ministry of Education and Science of the Republic of Kazakhstan (Project AP05130797)

The features of microcirculation in the nasal mucosa in children with adenoid hypertrophy and otitis media with effusion

At present, a reflex mechanism of the exudative otitis media (EOM) formation with pharyngeal tonsil hypertrophy (PTH) in children is suggested which includes a combination of several components on the background of neurovegetative imbalance of nasal mucosa vascular tone maintenance. Aim. To determine the state of microcirculation in the nasal mucosa in children with pharyngeal tonsil hypertrophy and exudative otitis media. Materials and methods. We observed 117 children with PTH and EOM aged between 5 and 7 years (mean age 6 years and 2 months) who had not previously undergone adenotomy or adenoidectomy. Two groups of clinical observation were formed: the group 1 included children with chronic purulent adenoiditis and EOM (n = 27); the group 2 included children with PTH and EOM (n = 90). The study of blood circulation in microvessels of the inferior nasal conchae mucous membrane was carried out using the LAKK-02 laser analyzer (RF), with the software “LDF 2.20.0.507WL”. Results. In each of the study groups, the vegetative index (VI) indicated the sympathetic tone predominance, and the values of the Hildebrandt coefficient (Q) pointed to the integrity of intersystem communication in vegetative innervation. Comparison of the VI indices, coefficient Q and microcirculation state of the inferior nasal conchae mucosa determined the statistically significant differences in all the studied parameters. Dependence of VI on neurotonus, myotonus and shunting index was not identified, reflecting the depletion of sympathetic innervation and the predominance of vagotonia. Conclusions. The presence of PTH is a focus of chronic irritation in children with EOM causing the development of vegetative innervation imbalance in the nasal and auditory tube mucosa with the predominance of parasympathetic component, prevalence of vasodilation, edema, increased vascular permeability and secretory activity of the glands, which contributes to otitis symptoms and their further maintenance

Existence of solutions for a higher order non-local equation appearing in crack dynamics

In this paper, we prove the existence of non-negative solutions for a non-local higher order degenerate parabolic equation arising in the modeling of hydraulic fractures. The equation is similar to the well-known thin film equation, but the Laplace operator is replaced by a Dirichlet-to-Neumann operator, corresponding to the square root of the Laplace operator on a bounded domain with Neumann boundary conditions (which can also be defined using the periodic Hilbert transform). In our study, we have to deal with the usual difficulty associated to higher order equations (e.g. lack of maximum principle). However, there are important differences with, for instance, the thin film equation: First, our equation is nonlocal; Also the natural energy estimate is not as good as in the case of the thin film equation, and does not yields, for instance, boundedness and continuity of the solutions (our case is critical in dimension $1$ in that respect)

Kinetic and isotherm study of as(Iii) removal from aqueous solution by pet track-etched membranes loaded with copper microtubes

This paper reports on the synthesis and structure elucidation of track-etched membranes (TeMs) with electrolessly deposited copper microtubes (prepared in etched-only and oxidized polyethylene terephthalate (PET) TeMs), as well as on the comparative testing of arsenic (III) ion removal capacities through bath adsorption experiments. The structure and composition of composites were investigated by X-ray diffraction technique and scanning electron and atomic force microscopies. It was determined that adsorption followed pseudo-second-order kinetics, and the adsorption rate constants were calculated. A comparative study of the applicability of the adsorption models of Langmuir, Freundlich, and Dubinin–Radushkevich was carried out in order to describe the experimental isotherms of the prepared composite TeMs. The constants and parameters of all of the above equations were determined. By comparing the regression coefficients R2, it was shown that the Freundlich model describes the experimental data on the adsorption of arsenic through the studied samples better than others. Free energy of As(III) adsorption on the samples was determined using the Dubinin–Radushkevich isotherm model and was found to be 17.2 and 31.6 kJ/mol for Cu/PET and Cu/Ox_PET samples, respectively. The high EDr value observed for the Cu/Ox_PET composite indicates that the interaction between the adsorbate and the composite is based on chemisorption. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.The research project titled “Development of functionalized composite track-etched membranes for environmental applications” (grant No. AP08855527) was funded by the Ministry of Education and Science of the Republic of Kazakhstan

Liquid low-level radioactive wastes treatment by using hydrophobized track-etched membranes

In this paper, we present the results of liquid low-level radioactive wastes (LLLRW) treatment by direct contact membrane distillation (DCMD) using polyethylene terephthalate (PET) track-etched membranes (TeMs). PET TeMs were modified by styrene and triethoxyvinylsilane (TEVS) using UV-induced grafting. Modification led to increase in the contact angle to 99° of PET TeMs (pore size from 150 to 300 nm). Hydrophobic PET TeMs were investigated by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), goniometric analysis, gas permeability test, liquid entry presser (LEP) analysis and scanning electron microscope (SEM). Prepared membranes were tested in treatment of LLLRW by DCMD. The influence of pore size on water flux and rejection degree was studied. Rejection degree was evaluated by conductometry and atomic emission methods. Decontamination factors (evaluated by gamma-ray spectroscopy) for 60Co, 137Cs, and 241Am were found to be 85, 1900 and 5 respectively. In most cases degree of rejection of Cs, Mo, Sr, Sb, Al, Ca, Fe, K, Mg and Na ions were more than 90% and close to 100%. The use of TeMs with a narrow pores size distribution and without tortuous channels allowed us to achieve better purification from radioactive wastes in comparison with hollow-fiber membranes. © 2019 Elsevier LtdMinistry of Education and Science of the Republic of Kazakhstan: AP05132110This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant No AP05132110 “Preparation of track-etched membranes with specified properties for membrane distillation and forward osmosis”)

Особливості мікроциркуляції в слизовій оболонці носу в дітей із гіпертрофією аденоїдів та ексудативним середнім отитом

At present, a reflex mechanism of the exudative otitis media (EOM) formation with pharyngeal tonsil hypertrophy (PTH) in children is suggested which includes a combination of several components on the background of neurovegetative imbalance of nasal mucosa vascular tone maintenance.Aim. To determine the state of microcirculation in the nasal mucosa in children with pharyngeal tonsil hypertrophy and exudative otitis media.Materials and methods. We observed 117 children with PTH and EOM aged between 5 and 7 years (mean age 6 years and 2 months) who had not previously undergone adenotomy or adenoidectomy. Two groups of clinical observation were formed: the group 1 included children with chronic purulent adenoiditis and EOM (n = 27); the group 2 included children with PTH and EOM (n = 90). The study of blood circulation in microvessels of the inferior nasal conchae mucous membrane was carried out using the LAKK-02 laser analyzer (RF), with the software “LDF 2.20.0.507WL”.Results. In each of the study groups, the vegetative index (VI) indicated the sympathetic tone predominance, and the values of the Hildebrandt coefficient (Q) pointed to the integrity of intersystem communication in vegetative innervation. Comparison of the VI indices, coefficient Q and microcirculation state of the inferior nasal conchae mucosa determined the statistically significant differences in all the studied parameters. Dependence of VI on neurotonus, myotonus and shunting index was not identified, reflecting the depletion of sympathetic innervation and the predominance of vagotonia.Conclusions. The presence of PTH is a focus of chronic irritation in children with EOM causing the development of vegetative innervation imbalance in the nasal and auditory tube mucosa with the predominance of parasympathetic component, prevalence of vasodilation, edema, increased vascular permeability and secretory activity of the glands, which contributes to otitis symptoms and their further maintenance. Предполагают рефлекторный механизм формирования экссудативного среднего отита (ЭСО) при гипертрофии глоточной миндалины (ГГМ) у детей, который включает комбинацию нескольких компонентов на фоне дисбаланса нейровегетативного обеспечения сосудистого тонуса слизистой оболочки носа.Цель работы – установить состояние микроциркуляции в слизистой оболочке носа у детей с ГГМ и ЭСО.Материалы и методы. Под наблюдением находились 117 детей с ГГМ и ЭСО в возрасте от 5 до 7 лет (средний возраст – 6,2 ± 0,3 года), ранее не подвергавшиеся аденотомии или аденоидэктомии. Сформированы 2 группы клинического наблюдения: 1 – дети с хроническим гнойным аденоидитом и ЭСО (n = 27); 2 – дети с ГГМ и ЭСО (n = 90). Циркуляцию крови в микрососудах слизистой оболочки нижних носовых раковин исследовали с использованием лазерного анализатора «ЛАКК-02» (РФ), программного обеспечения «LDF 2.20.0.507WL».Результаты. В каждой из исследуемых групп вегетативный индекс (ВИ) указывал на преобладание симпатического тонуса, а значение коэффициента Хильдебранта (Q) – на сохранность межсистемных отношений в вегетативной иннервации. Сравнения показателей ВИ, коэффициента Q и состояния микроциркуляции крови в слизистой оболочке нижних носовых раковин определяло наличие статистически значимых различий по всем исследуемым параметрам. Зависимость ВИ от нейротонуса, миотонуса и показателя шунтирования не прослеживалась, что свидетельствовало об истощении симпатической иннервации и преобладании ваготонии.Выводы. Наличие ГГМ у детей с ЭСО является очагом хронического раздражения, определяющим развитие дисбаланса вегетативной иннервации в слизистой оболочке носа и слуховой трубы с преобладанием парасимпатического компонента, превалированием вазодилатации, отеком, увеличением проницаемости сосудов и секреторной активности желез, что обусловливает появление признаков отита и поддержание их в дальнейшем. Є припущення про рефлекторний механізм формування ексудативного середнього отиту (ЕСО) при гіпертрофії глоткового мигдалика (ГГМ) у дітей, який включає комбінацію кількох компонентів на тлі дисбалансу нейровегетативного забезпечення судинного тонусу у слизовій оболонці носа.Мета роботи – встановити стан мікроциркуляції у слизовій оболонці носа в дітей із ГГМ та ЕСО.Матеріали та методи. Під наглядом перебували 117 дітей із ГГМ і ЕСО віком від 5 до 7 років (середній вік – 6,2 ± 0,3 року), яким раніше не виконували аденотомію або аденоїдектомію. Сформували 2 групи клінічного спостереження: 1– діти з хронічним гнійним аденоїдитом і ЕСО (n = 27); 2 – діти з ГГМ і ЕСО (n = 90). Циркуляцію крові в мікросудинах слизової оболонки нижніх носових раковин дослідили з використанням лазерного аналізатора «Лаккі-02» (РФ), програмного забезпечення «LDF 2.20.0.507WL».Результати. У кожній із досліджуваних груп вегетативний індекс (ВІ) вказував на переважання симпатичного тонусу, а значення коефіцієнта Гільдебранта (Q) – на збереження міжсистемних відносин у вегетативній іннервації. Порівняння показників ВІ, коефіцієнта Q і стану мікроциркуляції крові у слизовій оболонці нижніх носових раковин визначало наявність статистично значущих відмінностей за всіма досліджуваними параметрами. Залежність ВІ від нейротонусу, міотонусу та показника шунтування не виявлена, що свідчило про виснаження симпатичної іннервації та переважання ваготонії.Висновки. Наявність ГГМ у дітей з ЕСО є осередком хронічного подразнення, що зумовлює розвиток дисбалансу вегетативної іннервації у слизовій оболонці носа та слухової труби з переважанням парасимпатичного компонента, превалюванням вазодилятації, набряком, збільшенням проникності судин і секреторної активності залоз, спричиняючи появу ознак отиту й підтримання їх і надалі.

Dynamics of deformation band formation investigated by high-speed techniques during creep in an AlMg alloy

International audienceDynamics of the deformation band formation during creep in an Al-Mg alloy was investigated by simultaneous high-speed video recording of deformation bands with an extremely high time resolution of 40 µs and measurement of the concomitant acoustic emission. The results are consistent with the mechanism where the trigger of a strain step on the creep curve is the nucleation and rapid widening of a primary deformation band, generating an acoustic emission signal within one millisecond. Correlations between various stages of the deformation band formation, acoustic emission, and stress response are explored in detail. Notably, the stress drop rate and the amplitude of the acoustic emission signal are found to be linearly related. The mechanism of the acoustic emission associated with the initial rapid stage of the band development is discussed