Blend membranes of polybenzimidazole and an anion exchange ionomer (FAA3) for alkaline water electrolysis: Improved alkaline stability and conductivity

Konovalova, Anastasiia,Kim, Hyemi,Kim, Sangwon,Lim, Ahyoun,Park, Hyun Seo,Kraglund, Mikkel Rykær,Aili, David,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2018 Journal of membrane science Vol.564 No.-

<P><B>Abstract</B></P> <P>Anion exchange membranes (AEMs) conduct selectively hydroxide ions, while KOH doped polybenzimidazole is an ion-solvating polymer, conducting both potassium and hydroxide ions. In this work, meta-polybenzimidazole (mPBI) was blended with FAA3, a commercially available AEM, in the ratios of 2:1, 3:1, 4:1, 5:1 and 1:0. Doping was done by immersion in 0, 10, 15, 20, 25 and 30 wt% KOH solutions, giving rise to 30 membranes which were analyzed for their swelling behavior during doping, there composition (polymer, water, KOH), their mechanical properties and their through-plane conductivity in KOH solutions. Especially PF-41 showed higher tensile strength and Young's modulus than mPBI under all tested KOH concentrations. The highest conductivity of 166 mS cm<SUP>−1</SUP> was observed for PF-51 doped in 25% KOH, 80% higher than for mPBI. In an alkaline stability test, blend membranes showed higher tensile strength, Young's modulus and lower weight loss than mPBI after 4 weeks at 85 °C in 25 wt% KOH solution. PF-31 and PF-41 were also tested in an electrolysis cell, where they showed cell resistance comparable to mPBI. Because systems without cathode feed can be quite efficient, the permeability of membranes for KOH solutions was investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PBI and FAA3 were blended and doped with KOH solution. </LI> <LI> Composition (polymer, water, KOH) was analyzed. </LI> <LI> Blends show higher tensile strength and conductivity than PBI. </LI> <LI> Blends show higher alkaline stability (lower weight loss, higher tensile strength). </LI> <LI> In the electrolyzer, performance of the blends was similar to that of PBI. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The Possibilities of Cultural Diplomacy for Sustainable Development at Different Levels of Social Interactions

Pletsan, Khrystyna,Konovalova, Marta,Varenia, Nataliia,Khodanovych, Vitalii,Rozvadovskyi, Oleksandr International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.7

One of the important areas of state policy in the socio-economic and cultural development of the country is cultural diplomacy. It contributes to the information dissemination about the country, strengthens interstate relations, and forms a positive image. Through cultural diplomacy, we achieve a positive perception of the world community of the country, determined by its place in the modern system of international relations. The aim of the study is a comparative analysis of cultural diplomacy opportunities for sustainable development at different levels of public relations, as well as the impact of cultural diplomacy opportunities on the indicators of the Global Sustainable Competitiveness Index and the Global Sustainable Development Index. Regarding the results of the research on the impact of cultural diplomacy opportunities on the indicators of the Global Index of Sustainable Competitiveness and the Global Index of Sustainable Development, four groups are identified among the countries of the European Union: countries with a very high level of sustainable competitiveness and sustainable development; countries with a high level of sustainable competitiveness and sustainable development; countries with low levels of sustainable competitiveness and sustainable development.

Asymmetric Timeliness of Earnings, Market-To-Book and Conservatism in Financial Reporting in Kazakhstan

Aizhan Baimukhamedova,Yelena Konovalova,Rashid Makarov,Gulzada S. Baimukhamedova 한국유통과학회 2017 KODISA ICBE (International Conference on Business Vol.2017 No.-

Abstract should stand alone, means that no citation in abstract. The abstract should concisely This study extends the theoretical framework developed by Roychowdhury and Watts (2007) by testing it on a sample of Kazakhstani companies and aims at investigating changes in relations between two measures of conservatism: asymmetric timeliness of earnings (AT) and the market-to-book ratio (MTB) over short and long periods. On the contrary to the recent studies that document negative relations between these two measures, we reveal that magnitudes of earnings response to good and bad news increase for cumulation over longer periods. Second, we observe positive relations between earnings response to good news and MTB at the beginning and end of the estimation period. Even though the authors of the framework have not found any support for positive relations on any combination of news and MTB, our results support their initial expectations about positive association between asymmetric timeliness and MTB. Interestingly, our findings document absence of conservatism for certain lengths of cumulation period which can be attributed to peculiarities of financial reporting system on Kazakhstani Stock Exchange.

Experience in Using Peer-to-Peer Platforms and Immersive Technologies in the Training of Future Masters of Pharmacy in Medical Lyceum

Volodymyrovych, Tsekhmister Yaroslav,Tetiana, Konovalova,Yaroslavovych, Tsekhmister Bogdan International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.2

The present study has been conducted to evaluate the experience in using peer-to-peer platforms and immersive technologies in the training of future masters of pharmacy from the Pharmaceutical Faculty of Bogomolets National Medical University, Ukraine. The selected participants were given the pre- and post-test containing multiple choice questions to assess the effectiveness of immersive technologies. Further, a self-designed structured questionnaire contained 10 questions with 5 options was delivered to consented participants through email and WhatsApp. The results of test presented that students attained an average of 26% in their pre-test while the average attained score post-test was 74% that showed a significant improvement with peer-to-peer platforms and virtual reality technology. The results of survey questions also showed an overall 86.73% satisfaction for the use of peer-to-peer platforms and virtual reality technology in the training of future masters of pharmacy. These results demonstrated that 90.81% showed agreement that they gained a high level of confidence through peer-to-peer platforms and virtual reality to handle patients in clinical practice. It can be concluded that participants of this study showed a strong agreement with positive experience in using peer-to-peer platforms and virtual reality technology in the training of future masters of pharmacy in medical lyceum.

Using neutron methods SANS and PGAA to study evolution of structure and composition of alkali-doped polybenzimidazole membranes

Babcock, E.,Szekely, N.,Konovalova, A.,Lin, Y.,Appavou, M.-S.,Mangiapia, G.,Revay, Z.,Stieghorst, C.,Holderer, O.,Henkensmeier, D.,Lehnert, W.,Carmo, M. Elsevier 2019 Journal of membrane science Vol.577 No.-

<P><B>Abstract</B></P> <P>Potassium hydroxide (KOH) doped polybenzimidazole (PBI) membranes are investigated as compelling candidates for water electrolysis applications, drastically reducing the ohmic losses in contrast to thick ZrO<SUB>2</SUB> based diaphragms. Using small angle neutron scattering (SANS) we have found that the structure of the (KOH doped) PBI changes with doping time on a minute time scale, and that the development of the structure is highly dependent on the KOH concentration. This data is correlated with macroscopic measurements of membrane swelling resulting from the doping process which also occurs on a minute time scale. Then, using prompt gamma activation analysis (PGAA) to follow the changes in time of the chemical composition, we have found that the K concentration of these samples only increases slightly with doping times after a very rapid initial uptake, reaching a saturation value that is relatively independent of KOH concentration for long doping times of up to 24 h. However measurements of similarly doped samples show increases in ion-conductivity of nearly 3 fold, and resistivity reductions of over 2 fold on the same time scales. These measurements prove that PGAA is a sensitive method to follow changes in the chemical compositions during doping, while SANS can give information on the sub-micro structural changes of polymer electrolyte membranes. Since these methods can be correlated with <I>ex-situ</I> measurements of composition, resistance, ion-conductivity and macro-structure, the combined use of PGAA and SANS provides a promising means for <I>in-operando</I> study in order to elucidate changes in membrane performance due to electrochemical cycling, as well as to help characterize and optimize doping parameters though in-situ doping measurements, by enabling real-time study of such membrane systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Elucidating the doping of Alkali-doped Polybenzimidazole membranes. </LI> <LI> Complementary structure and composition information from SANS and PGAA to study functional membranes. </LI> <LI> Structure varies over doping time for KOH doped Polybenzimidazole membranes. </LI> <LI> New possibilities for in-situ and in-operando characterization. </LI> </UL> </P>

Thermally crosslinked sulfonated polybenzimidazole membranes and their performance in high temperature polymer electrolyte fuel cells

Nambi Krishnan, N.,Konovalova, Anastasiia,Aili, David,Li, Qingfeng,Park, Hyun Seo,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2019 Journal of membrane science Vol.588 No.-

<P><B>Abstract</B></P> <P>The degradation pathway of phosphoric acid doped polybenzimidazole membranes in high temperature polymer electrolyte membrane fuel cells depends on the acid contents. If it is high, creep is discussed as the main reason. If it is low (membranes prepared by solvent evaporation and post-doping), the main cause may be loss of acid due to evaporation. The net transport of acid to the anode side at high current densities should also lead to local softening of the membrane, which could be mitigated by crosslinking the membrane.</P> <P>Here we show that sulfonated <I>para</I>-polybenzimidazole membranes can be stabilized by curing at 350 °C. In contrast to <I>meta</I>-polybenzimidazole and sulfonated <I>para</I>-polybenzimidazole, crosslinked sulfonated <I>para</I>-polybenzimidazole is insoluble in dimethylacetamide at room temperature and phosphoric acid at 160 °C. At 160 °C and 5% relative humidity the conductivity of crosslinked sulfonated <I>para</I>-polybenzimidazole and <I>meta</I>-polybenzimidazole is 214 mS cm<SUP>−1</SUP> and 147 mS cm<SUP>−1</SUP>, respectively. At 600 mA cm<SUP>−</SUP> <SUP>2</SUP>, the voltage decay rate is 16 μV h<SUP>−1</SUP>, much lower than published for commercial <I>meta</I>-polybenzimidazole (308 μV h<SUP>−1</SUP>). Furthermore, the average voltage at 600 mA cm<SUP>−</SUP> <SUP>2</SUP> is 523 mV, while a previously published cured <I>meta</I>-polybenzimidazole membrane only reaches 475 mV.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfonated <I>para</I>-PBI is covalently crosslinked by heating. </LI> <LI> Membranes are stable in DMAc at 27 °C and in 85 wt% phosphoric acid at 160 °C. </LI> <LI> Non-crosslinked sulfonated <I>para</I>-PBI and <I>meta</I>-PBI dissolve under these conditions. </LI> <LI> Conductivity is 44% higher than for <I>meta</I>-PBI. </LI> <LI> Fuel cell performance is stable; test time was 2100 h, half of that at 600 mA/cm<SUP>2</SUP> </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Blending polybenzimidazole with an anion exchange polymer increases the efficiency of vanadium redox flow batteries

Jung, Mina,Lee, Wonmi,Noh, Chanho,Konovalova, Anastasiia,Yi, Gyu Seong,Kim, Sangwon,Kwon, Yongchai,Henkensmeier, Dirk Elsevier 2019 Journal of membrane science Vol.580 No.-

<P><B>Abstract</B></P> <P>PBI membranes are recently discussed as stable, well performing membranes for vanadium redox flow batteries (VRFB). Blending meta-PBI with an anion exchange polymer (FAA3i) slightly reduces the coulomb efficiency from 99.7 to 97.8%, but strongly increases the voltage efficiency from 82.5 to 88.2%, leading to an increased energy efficiency (86.2% at 80 mA cm<SUP>−2</SUP>), exceeding that of meta-PBI (82.2%) and N212 (83%). Apparently, since the conductivity of sulfuric acid has a maximum around a concentration of 3.8 M, the concentration of the absorbed acid has a dominant influence on the conductivity. Addition of FAA3i decreases the concentration of the acid absorbed by PBI membranes. Furthermore, an ex-situ stability test in 1.5 M V<SUP>5+</SUP> solutions in 2 M sulfuric acid for 87 days showed a very high stability for meta-PBI and Nafion 212, while the commercial FAA3 membrane disintegrated into pieces. Blending of meta-PBI and FAA3 decreased the stability, as proven by formation of V<SUP>4+</SUP>, but all tested blend membranes retained their membrane shape and could still be handled. Blending with FAA3 reduces the tensile strength and Young's modulus of meta-PBI, and doping with sulfuric acid leads to a further decrease in the mechanical strength. However, an acid doped PF-21 still showed a tensile strength of 37 MPa and a Young's modulus of 0.7 GPa.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PBI and FAA3 (an AEM) were blended and doped with sulfuric acid for use in VRFB. </LI> <LI> Coulomb efficiency slightly decreased, but voltage efficiency strongly increased. </LI> <LI> Energy efficiency at 80 mA/cm<SUP>2</SUP> reached 86.2%, higher than that of Nafion 212 (83%). </LI> <LI> Stability of blends against VO<SUB>2</SUB> <SUP>+</SUP> increases with amount of PBI in the blends. </LI> <LI> Doping decreases the tensile strength, but acid doped PF-21 still had a TS of 37 MPa. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Polybenzimidazole (PBI-OO) based composite membranes using sulfophenylated TiO₂ as both filler and crosslinker, and their use in the HT-PEM fuel cell

Krishnan, N. Nambi,Lee, Sangrae,Ghorpade, Ravindra V.,Konovalova, Anastasiia,Jang, Jong Hyun,Kim, Hyoung-Juhn,Han, Jonghee,Henkensmeier, Dirk,Han, Haksoo Elsevier 2018 Journal of membrane science Vol.560 No.-

<P><B>Abstract</B></P> <P>Crosslinked metal oxide containing nanocomposite membranes, in which the filler also acts as crosslinker, were prepared by blending polybenzimidazole (PBI-OO) and phenylsulfonated TiO<SUB>2</SUB> particles (s-TiO<SUB>2</SUB>). Thermal curing changes the ionically crosslinked system into a covalently crosslinked system. The synthesized s-TiO<SUB>2</SUB> nanoparticles were analyzed by thermal gravimetric analysis and scanning electron microscopy. The covalently crosslinked nanocomposite membranes (c-sTiO<SUB>2</SUB>-PBI-OO) were doped with phosphoric acid (PA) for high temperature proton exchange membrane fuel cell (HT-PEMFC) application. The membrane properties, such as PA uptake, dimensional change, gel content, proton conductivity, mechanical property, and single cell performance were evaluated and compared with the properties of acid-doped c-PBI-OO. PA doped 6-c-sTiO<SUB>2</SUB>-PBI-OO (6 wt% sTiO<SUB>2</SUB>) showed the highest uptake of 392 wt%, and a proton conductivity at 160 °C of 98 mS cm<SUP>−1</SUP>. In the fuel cell, a peak power density of 356 mW cm<SUP>−2</SUP> was obtained, which is 76% higher than that of a c-PBI-OO based system (202 mW cm<SUP>−2</SUP>). To evaluate the stability of the membrane performance over time, the best performing membrane was tested for over 700 h.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PBI-OO is filled with sulfophenylated TiO<SUB>2</SUB> nanoparticles. </LI> <LI> the ionically crosslinked structure changes into a covalent network by thermal curing. </LI> <LI> conductivity at 160 °C is 98 mS cm<SUP>−1</SUP>. </LI> <LI> peak power density in the HT-PEMFC is 356 mW cm<SUP>−2</SUP>. </LI> <LI> at 600 mA cm<SUP>−2</SUP> the voltage degrades at 55.4 µV h<SUP>−1</SUP>, indicating a stable performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Sepiolite Clay Attenuates the Development of Hypercholesterolemia and Obesity in Mice Fed a High-Fat High-Cholesterol Diet

Roee Gutman,Maayan Rauch,Annat Neuman,Hazem Khamaisi,Adi Jonas-Levi,Yelena Konovalova,Giora Rytwo 한국식품영양과학회 2020 Journal of medicinal food Vol.23 No.3

Obesity reduces the quality of life and life expectancy, whereas nonoperative interventions have shown poor results so far. Statins effectively combat hypercholesterolemia but are not well tolerated at high doses, raising the need for coprescription with cholesterol sorbents and/or absorption inhibitors. Montmorillonite (MMT) clay was found to attenuate hypercholesterolemia and obesity by reducing cholesterol and fat absorption. However, acicular clay-like sepiolite may offer better results due to its more substantial adsorption of nonpolar molecules. We herein aimed at (1) assessing in vitro the capacity of sepiolite to adsorb edible oil and cholesterol compared with that of MMT and (2) assessing in vivo the effect of continuous feeding on a high-fat high-cholesterol diet (HFD) (53.6% w/w fat and 0.2% cholesterol) supplemented with 5% (w/w) edible sepiolite, on diet-induced obesity rate, hypercholesterolemia, and hyperlipidemia. Fourier transform infrared spectroscopy showed in vitro that sepiolite adsorption of olive oil and cholesterol was five to eight times greater than that of MMT clay. Sepiolite supplementation to HFD fed to mature mice for 12.5 weeks resulted in lower total blood cholesterol and triacylglycerol levels and attenuated body weight gain, by reducing fat gain. Sepiolite supplementation did not affect energy intake but increased fecal extraction of sterols and lipids, without notable side effects. These results demonstrate that supplementing a HFD with sepiolite attenuates gastrointestinal absorption of dietary lipids and sterols, thus mitigating obesity, hyperlipidemia, and hypercholesterolemia. Further exploration of the efficacy, mechanism of action, and safety of sepiolite as a food supplement for combating the metabolic syndrome is needed.

Improvement of the Administration System of Customs Payments in the Modern Conditions

Mishina, Natalya V.,Kuzminov, Vitaly A.,Kuzminova, Olga A.,Konovalova, Elena E.,Gubanova, Natalia V. International Journal of Computer ScienceNetwork S 2022 International journal of computer science and netw Vol.22 No.10

The article is devoted to the formation of approaches to improving the system of administration of customs payments in modern conditions. It is established that important components of the administration of customs payments are customs expertise, customs value assessment, and control over the declaration of goods to ensure the completeness and timeliness of customs duties payments to the budget. It is found that the practice of customs administration shifts the emphasis of foreign trade regulation to the use of the principles of work implying the use of the latest technologies for the preliminary electronic exchange of information, remote customs clearance of goods without the physical presence of an official, and consistent application of risk management. It is established that an important place in the structure of the state authorities regulating the foreign economic activity is given to the customs service. Furthermore, the existing problems in the implementation of international trade operations necessitate the improvement of approaches to the customs regulation of export-import activities of enterprises.