3,721 research outputs found
New generation of lithium-air energy storage systems
No full textQuesta tesi analizza lo sviluppo di batterie litio-aria (Li–O2) come alternativa alle tradizionali batterie agli ioni di litio. L'attenzione è focalizzata sull'innovazione dei materiali per anodi e catodi, nonché sull'ottimizzazione degli elettroliti, al fine di soddisfare le crescenti esigenze energetiche della società contemporanea e promuovere la sostenibilità. Le batterie Li–O2 offrono un’elevata densità energetica teorica e potenziali benefici ambientali; tuttavia, la loro applicazione pratica è ostacolata dall’instabilità dell’anodo e dell’elettrolita, oltre alla limitata durata del ciclo di vita. Il presente studio affronta queste problematiche mediante la sintesi di nuovi materiali e il perfezionamento dei componenti della batteria, con l’obiettivo di migliorarne le prestazioni e la durabilità.
Il lavoro inizia dallo studio di anodo nanostrutturato Sn@C come alternativa al litio metallico, con l’obiettivo di mitigare la formazione di dendriti. Il composito Sn@C, costituito da nanoparticelle di stagno disperse in una matrice di carbonio, si distingue per un’eccellente ritenzione della capacità, un’elevata densità energetica e una vita utile che si estende fino a 300 cicli, con ridotta polarizzazione e un’efficienza coulombica prossima al 100%, confermando il potenziale del materiale come candidato promettente per batterie di nuova generazione.
L’accoppiamento con un catodo spinello (LiNi0.35Cu0.1Mn1.45Al0.1O4) consente la realizzazione di una cella agli ioni di litio con una tensione operativa media di 4,3 V e una densità energetica teorica prossima a 500 Wh/kg, con un valore densità energia pratica di 165 Wh/kg.
Per migliorare le prestazioni delle batterie Li–O2, è stata condotta un’analisi approfondita dei gas diffusion layer (GDL) a base di carbonio, valutandone la morfologia, la porosità e le proprietà strutturali. Successivamente, il GDL 39BB è stato ricoperto con un composito di nanotubi di carbonio e Few Layer Graphene, ottenendo una cella con una durata superiore a 100 cicli a una capacità di 500 mAh g−1.
L’attenzione è stata successivamente rivolta all’ottimizzazione dei materiali catodici, basati su MWCNTs e FLG in diverse proporzioni, con l’aggiunta di un catalizzatore a base di oro nanometrico. Questa configurazione ha consentito un significativo miglioramento della reversibilità e della cinetica delle reazioni elettrochimiche dell’ossigeno, garantendo una maggiore stabilità del sistema e un incremento dell’output energetico. Il materiale catodico più performante, costituito da MWCNTs e FLG in rapporto 50:50, con l’aggiunta dell’8% di Au, ha raggiunto una capacità di 954 mAh g−1, mantenendo un’efficienza coulombica del 100% per oltre 70 cicli.
Sono stati inoltre sviluppati elettroliti a base di PEGDME 250, combinato con i sali LiTFSI e LiNO3, con l’obiettivo di ottenere soluzioni elettrolitiche più stabili ed ecosostenibili. Le formulazioni risultanti presentano eccellente stabilità termica, un’ampia finestra elettrochimica, elevata conducibilità ionica e un numero di trasferimento adeguato.
Infine, è stata sviluppata, come proof-of-concept, una cella Li-ione/O2 che integra l’anodo Sn@C, il catodo MWCNT/FLG 50:50 e gli elettroliti a base di PEGDME 250.I risultati preliminari evidenziano che la cella con elettrolita privo di LiNO3 ha raggiunto una capacità specifica di 350 mAh g−1, mentre la cella contenente LiNO3 ha raggiunto una capacità specifica di 275 mAh g−1.
Il presente studio fornisce un contributo significativo allo sviluppo di materiali elettrodici ed elettroliti ad alte prestazioni, favorendo il progresso dei sistemi di accumulo elettrochimico. Le innovazioni proposte delineano un percorso promettente verso soluzioni di accumulo energetico più sostenibili, scalabili ed economicamente vantaggiose, agevolando l’integrazione delle fonti rinnovabili e il progresso della mobilità elettrica.This thesis examines the development of advanced lithium-air (Li–O2) battery systems as an alternative to conventional lithium-ion batteries. It focuses on the investigation of innovative anode and cathode materials, as well as optimized electrolytes, to address the growing energy demands of modern society while fostering sustainability.
Li–O2 batteries hold significant promise due to their high theoretical energy density and environmental advantages.
However, their practical application is constrained by challenges such as anode instability, electrolyte degradation, and limited cycle life.
This work seeks to address these obstacles through the synthesis of novel materials and the optimization of battery components to achieve enhanced performance and durability.
The study introduces a nanostructured Sn@C alloying anode as a replacement for lithium metal, addressing issues related to dendrite formation, which pose safety risks and limit cycling life.
The Sn@C composite, consisting of tin nanoparticles embedded within a carbon matrix, exhibits excellent capacity retention, high tap density, and a cycle life of up to 300 cycles. Electrochemical analysis demonstrates reduced polarization and a charge-discharge efficiency nearing 100%, positioning it as a promising candidate for next-generation batteries.
When combined with a high-voltage spinel cathode, LiNi0.35Cu0.1Mn1.45 Al0.1O4, the resulting Li-ion full cell achieves an average working voltage of 4.3 V and an energy density approaching 500 Wh/kg, with practical outputs of 165 Wh/kg.
A comprehensive evaluation of carbon-based gas diffusion layers (GDLs) was conducted to improve the performance of Li–O2 batteries.
GDLs with varying morphology, porosity, and structural properties were characterized and tested to assess their influence on ion diffusion kinetics and electrode stability.
Then GDL 36BB was subsequently coated with a composite of Multi Walled Carbon Nanotubes (MWCNTs) and Few Layer Graphene (FLG), resulting in a cell that demonstrated a lifespan exceeding 100 cycles at a capacity of 500 mAh g-1.
The research subsequently focuses on improving cathode materials composed of MWCNTs and Few- FLG in various ratios, further enhanced with nanometric gold catalysts.
This configuration markedly improves the reversibility and kinetics of oxygen electrochemical reactions, enabling stable cycling and increased energy output.
The most effective cathodic material, comprising a 50:50 ratio of MWCNTs and FLG, with addition of 8% Au catalyst, achieves a cell capacity of 954 mAh g-1, sustained over 70 cycles with 100% efficiency.
Electrolytes based on PEGDME 250 with LiTFSI and LiNO3 salts have been developed to achieve greener and more stable electrolyte solutions.
These formulations exhibit excellent thermal stability, ranging from -50 °C to 200 °C, a broad electrochemical window, high ionic conductivity, an appropriate transference number (~0.6 for both electrolytes), and facilitate the formation of a robust solid electrolyte interphase (SEI).
Finally, a proof-of-concept Li-ion/O2 cell was developed, incorporating the Sn@C anode, the MWCNT/FLG 50:50 cathode, and PEGDME 250-based electrolytes.
Preliminary results demonstrated that the cell with a LiNO3-free electrolyte achieved a capacity of 350 mAh g-1 while the cell containing LiNO3 exhibited a capacity of 275 mAh g-1, both cells with a lifecycle of 40 cycles.
This comprehensive study provides critical insights into the development of high-performance and environmentally friendly electrode materials and electrolytes for lithium-air batteries, contributing to the advancement of electrochemical energy storage systems.
The innovations presented herein represent a promising pathway toward cost-effective, sustainable, and scalable battery solutions, enabling greater integration of renewable energy and supporting the growth of electric mobility
Pros and Cons of (NH4)2S Solution Treatment of p-GaN/Metallization Interface: Perspectives for Laser Diode
No full textThe impact of wet treatment using an (NH4)2S-alcohol solution on the interface state of the p-GaN/Ni/Au/Pt contact system and laser diode processing was investigated. Sulfur wet cleaning resulted in reduced surface roughness and contact resistivity. The lowest specific contact resistance (ρc < 1 × 10−4 Ω·cm2) was achieved with samples treated with an (NH4)2S-isopropanol solution, whereas the highest resistivity (ρc = 3.3 × 10−4 Ω·cm2) and surface roughness (Ra = 16 nm) were observed in samples prepared by standard methods. Annealing the contact system in an N2 + O2 + H2O atmosphere caused degradation through species inter-diffusion and metal-metal solid solution formation, irrespective of the preparation method. Standard prepared substrates developed a thin GaN-Au intermediate layer at the interface after heat treatment. Enhanced adhesion and the absence of GaN decomposition were observed in samples additionally cleaned with the (NH4)2S-solvent solution. Complete oxidation of nickel to NiO was observed in samples that underwent additional sulfur solution treatment. The intensity of metal species mixing and nickel oxidation was influenced by the metal diffusion rate and was affected by the initial state of the GaN substrate obtained through different wet treatment methods.The names of files corespond to the numbering of the figures in the paper Iryna Levchenko,Serhii Kryvyi,Eliana Kamińska,Julita Smalc-Koziorowska,Szymon Grzanka,Jacek Kacperski,Grzegorz Nowak,Sławomir Kret,Łucja Marona and Piotr Perlin. Pros and Cons of (NH4)2S Solution Treatment of p-GaN/Metallization Interface: Perspectives for Laser Diode. https://doi.org/10.3390/ma17184520.Files include next collection:Figure 1. AFM overview scan of p-GaN surface after (a) standard cleaning and (b) standard and (NH4)2S-t-(CH3)3COH treatment.Figure 2. AFM maps (a–d) and SEM images (e–h) of the surface of annealed p-GaN/Ni/Au/Pt contact system.Figure 3. c-AFM current maps (a–d) and AFM images (e–h) of annealed p-GaN/Ni/Au/Pt.Figure 4. STEM image of annealed p-GaN/Ni/Au/Pt, after standard preparation (a) and with additional treatment by (NH4)2S solution (b).Figure 5. STEM image (a) and EDX maps of the element propagation (b–f) for the annealed p-GaN/Ni/Au/Pt system with treatment in (NH4)2S-based solution.Figure 6. Schematic view on evolution of the annealed p-GaN/Ni/Au/Pt system with treatment in (NH4)2S-based solution (grey circles represent the voids).Figure 7. STEM image (a) and EDX maps of the element dispersion (b–f) for the annealed p-GaN/Ni/Au/Pt system after standard cleaning.Figure 8. Schematic view on evolution of the annealed p-GaN/Ni/Au/Pt system after standard cleaning.</p
Гепатопротекторное и антидисбиотическое действие высокоолеинового подсолнечного масла (экспериментальное исследование) = Hepatoprotective and antidysbiotic effects of high oleic sunflower oil (experimental investigation)
No full textLevchenko Ye. M. Гепатопротекторное и антидисбиотическое действие высокоолеинового подсолнечного масла (экспериментальное исследование) = Hepatoprotective and antidysbiotic effects of high oleic sunflower oil (experimental investigation). Journal of Education, Health and Sport. 2015;5(11):735-744. eISSN 2391-8306. DOI http://dx.doi.org/10.5281/zenodo.48417
http://ojs.ukw.edu.pl/index.php/johs/article/view/3436
http://pbn.nauka.gov.pl/works/722454
The journal has had 7 points in Ministry of Science and Higher Education parametric evaluation. Part B item 755 (23.12.2015).
755 Journal of Education, Health and Sport (null) 2391-8306 7
© The Author (s) 2015;
This article is published with open access at Licensee Open Journal Systems of Kazimierz Wielki University in Bydgoszcz, Poland.
Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium,
provided the original author(s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License
(http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited.
This is an open access article licensed under the terms of the Creative Commons Attribution Non Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non commercial
use, distribution and reproduction in any medium, provided the work is properly cited.
The authors declare that there is no conflict of interests regarding the publication of this paper.
Received: 15.11.2015. Revised 20.11.2015. Accepted: 30.11.2015.
УДК 616.33:342.092
ГЕПАТОПРОТЕКТОРНОЕ И АНТИДИСБИОТИЧЕСКОЕ ДЕЙСТВИЕ ВЫСОКООЛЕИНОВОГО ПОДСОЛНЕЧНОГО МАСЛА (ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ)
Е. М. Левченко
Коммунальное учреждение «Одесская областная клиническая больница МЗУ»,
г. Одесса, Украина
e-mail: [email protected]
Резюме
Обычное подсолнечное масло (высоколинолевое) вызывает у крыс развитие стеатоза печени. Высокоолеиновое подсолнечное масло оказывает гепатопротекторное и антидисбиотическое действие.
Ключевые слова: подсолнечное масло, олеиновая кислота, печень, дисбиоз, жировой обмен.
HEPATOPROTECTIVE AND ANTIDYSBIOTIC EFFECTS OF HIGH OLEIC SUNFLOWER OIL (EXPERIMENTAL INVESTIGATION)
Ye. M. Levchenko
Municipal Institution «Odessa Regional Hospital», Odessa, Ukraine
e-mail: [email protected]
Summary
Aim: To make comparative estimate of action on liver by high oleic sunflower oil.
Methods: Usual (linoleic) sunflower oil and high oleic sunflower oil were used. Rats were feed nonfat ration (NFR) – 1 group, NFR + 5 % usual sunflower oil – 2 group, and NFR + 5 % high oleic sunflower oil – 3 group. The feeding was continued 30 days. The content of triglycerides (TG), common cholesterine (CC) malondialdegyde (MDA), activities of elastase, urease, lysozyme, catalase, alkaline phosphatase (AP) were determined in the homogenates of liver. Activities of AP and ALT were determined in serum. The degree of dysbiosis was calculated by using the ratio of relative activities of urease and lysozyme. Antioxydante-prooxydante index API was calculated by ratio of catalase activity and content of MDA.
Results: The increase of TG and CC contents and the activities of elastase and AP was stated in liver. High oleic sunflower oil no rised the levels of TG, CC, elastase and AP but decreased the levels of urease activity and dysbiosis degree in liver.
Conclusion: The high oleic sunflower oil exerts hepatoprotective and antidysbiotic actions in contrast to linoleic sunflower oil.
Keywords: sunflower oil, oleic acid, liver, dysbiosis, fatty metabolism
The success or failure of integration in sub-Saharan Africa
No full textCHARLES UNIVERSITY IN PRAGUE FACULTY OF SOCIAL SCIENCES Master's thesis in the programme..........IEPS....................................................... 1. Given name and Surname of author: Daria Levchenko 2. Title of the Thesis: "The success or failure of integration process in Sub-Saharan Africa" 3. Subordinate title: .......................................……………………………………………….. 4. Year of defence: 2014 5. Number of pages: 141 6. Summary of the Thesis: The Diploma thesis "The success or failure in Sub-Saharan Africa" deals with a topical issue of the integration process in Sub-Saharan Africa. For the last couple of decades, the whole world was under the influence of the integration. The popularity of such economic blocks as the European Union, NAFTA, ASEAN and others lead to further interest in this field. Therefore, it is quite obvious that other countries and regions started to think about similar way of the development, and Sub-Saharan Africa is also among them. The process of integration has started at this continent long time ago, half a century. Ever since countries in the Sub-Saharan Africa gained independence, they started to build their own blocks (communities). Decades of colonial periods, struggle for freedom, the final gain of the independence, and now fight for building united and strong..
Comparative Advantage, International Trade, and Fertility
No full textWe analyze theoretically and empirically the impact of comparative advantage in international trade on fertility. We build a model in which industries differ in the extent to which they use female relative to male labor, and countries are characterized by Ricardian comparative advantage in either female- or male-intensive goods. The main prediction of the model is that countries with comparative advantage in female-intensive goods are characterized by lower fertility. This is because female wages, and therefore the opportunity cost of child-rearing are higher in those countries. We demonstrate empirically that countries with comparative advantage in industries employing primarily women exhibit lower fertility. We use a geography-based instrument for trade patterns to isolate the causal effect of comparative advantage on fertility.Fertility, trade integration, comparative advantage, factor endowments
Cold transiently activates calcium-permeable channels in Arabidopsis mesophyll cells
No full textLiving organisms are capable of discriminating thermal stimuli from noxious cold to noxious heat. For more than 30 years, it has been known that plant cells respond to cold with a large and transient depolarization. Recently, using transgenic Arabidopsis (Arabidopsis thaliana) expressing the calcium-sensitive protein aequorin, an increase in cytosolic calcium following cold treatment was observed. Applying the patch-clamp technique to Arabidopsis mesophyll protoplasts, we could identify a transient plasma membrane conductance induced by rapid cooling. This cold-induced transient conductance was characterized as an outward rectifying 33 pS nonselective cation channel. The permeability ratio between calcium and cesium was 0.7, pointing to a permeation pore >3.34 A (ø of cesium). Our experiments thus provide direct evidence for the predicted but not yet measured cold-activated calcium-permeable channel in plants
Holocene evolution of the granite based Lizard Island and MacGillivray Reef systems, Northern Great Barrier Reef
No full textRadiocarbon dating of seven drill cores from both the windward Lizard Island fringing reef and the windward and leeward margins of MacGillivray platform reef, Northern Great Barrier Reef Province, reveal the Holocene evolution of these two mid shelf coral reefs. The windward margin at Lizard Island started growing approximately 6,700 calendar years before present (cal yr BP) directly on an assumed granite basement and approached present day sea level approximately 4,000 cal yr BP. Growth of the windward margin at MacGillivray Reef was initiated by 7,600 cal yr BP and approached present day sea level by approximately 5,600 cal yr BP. The leeward margin at MacGillivray was initiated by 8,200 cal yr BP also directly on an assumed granite basement, but only approached sea level relatively recently, between 260 and 80 cal yr BP. None of the cores penetrated the Holocene-Pleistocene unconformity. The absence of Pleistocene reefal deposits, at 15 m depth in the cores from MacGillivray Reef, raises the possibility that the shelf in this region has subsided relative to modern day sea level by at least 15 m since the last interglacial [125,000 years ago (ka)]
Russkij formalizm i eksperimental'naja avtobiograficheskaja proza Andreja Belogo
No full textIl presente articolo è dedicato allo studio delle strategie di autorappresentazione messe in atto da Andrej Belyj nel ciclo "Epopeja" ("Kotik Letaev", 1918; "Krescenyj kitaec", 1921; "Zapiski cudaka", 1922), interpretate attraverso il prisma teorico delineato dai formalisti russi. Particolare attenzione è dedicata all'apparato paratestuale e alla costruzione "ad anello" della trilogia
Coupling of manometric and calorimetric measurements to probe unique characterization of solid hydrogen storage systems
No full textThe utility of coupling manometric and calorimetric measurements to probe unique characteristics of solid hydrogen storage systems is discussed. Some practical applications are presented
Russian Federation: Vladimir Levchenko
No full textA document from Amnesty International's Urgent Action Networ
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