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91.
Andrea Basso Peressut Matteo Di Virgilio Antonella Bombino Saverio Latorrata Esa Muurinen Riitta L. Keiski Giovanni Dotelli 《Molecules (Basel, Switzerland)》2022,27(5)
This work deals with the development of graphene oxide (GO)-based self-assembling membranes as possible innovative proton conductors to be used in polymer electrolyte membrane fuel cells (PEMFCs). Nowadays, the most adopted electrolyte is Chemours’ Nafion; however, it reveals significant deficiencies such as strong dehydration at high temperature and low humidity, which drastically reduces its proton conductivity. The presence of oxygenated moieties in the GO framework makes it suitable for functionalization, which is required to enhance the promising, but insufficient, proton-carrying features of GO. In this study, sulfonic acid groups (–SO3H) that should favor proton transport were introduced in the membrane structure via a reaction between GO and concentrated sulfuric acid. Six acid-to-GO molar ratios were adopted in the synthesis procedure, giving rise to final products with different sulfonation degrees. All the prepared samples were characterized by means of TGA, ATR-FTIR and Raman spectroscopy, temperature-dependent XRD, SEM and EDX, which pointed out morphological and microstructural changes resulting from the functionalization stage, confirming its effectiveness. Regarding functional features, electrochemical impedance spectroscopy (EIS) as well as measurements of ion exchange capacity (IEC) were carried out to describe the behavior of the various samples, with pristine GO and commercial Nafion® 212 used as reference. EIS tests were performed at five different temperatures (20, 40, 60, 80 and 100 °C) under high (95%) and medium (42%) relative humidity conditions. Compared to both GO and Nafion® 212, the sulfonated specimens demonstrate an increase in the number of ion-carrying groups, as proved by both IEC and EIS tests, which reveal the enhanced proton conductivity of these novel membranes. Specifically, an acid-to-GO molar ratio of 10 produces a six-fold improvement of IEC (4.23 meq g−1) with respect to pure GO (0.76 meq g−1), while a maximum eight-fold improvement (5.72 meq g−1) is achieved in SGO-15. 相似文献
92.
Leskinen Anumaija Salminen-Paatero Susanna Räty Antti Tanhua-Tyrkkö Merja Iso-Markku Taneli Puukko Esa 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(1):399-413
Journal of Radioanalytical and Nuclear Chemistry - Determination of 14C, 55Fe, 63Ni and gamma emitters in two different types of activated reactor pressure vessel (RPV) steel samples were carried... 相似文献
93.
94.
Jussi Putaala Jari Hannu Esa Kunnari Matti Mäntysalo Olli Nousiainen Heli Jantunen 《Microelectronics Reliability》2014
This work dealt with potential reliability issues in inkjet-printed electronics. The aim was to increase our understanding of how failures occur in hybrid electronic structures that utilize inkjet printing. A future goal in this field will be to enable expansion of this product area from low-life-expectancy and -performance products to high-life-expectancy and -performance products. 相似文献
95.
Ping Huang Fikret Mamedov Stenbjörn Styring Esa Tyystjärvi 《Photochemistry and photobiology》2014,90(5):965-971
Singlet oxygen, a harmful reactive oxygen species, can be quantified with the substance 2,2,6,6‐tetramethylpiperidine (TEMP) that reacts with singlet oxygen, forming a stable nitroxyl radical (TEMPO). TEMPO has earlier been quantified with electron paramagnetic resonance (EPR) spectroscopy. In this study, we designed an ultra–high‐performance liquid chromatographic—tandem mass spectrometric (UHPLC‐ESI‐MS/MS) quantification method for TEMPO and showed that the method based on multiple reaction monitoring (MRM) can be used for the measurements of singlet oxygen from both nonbiological and biological samples. Results obtained with both UHPLC‐ESI‐MS/MS and EPR methods suggest that plant thylakoid membranes produce 3.7 × 10?7 molecules of singlet oxygen per chlorophyll molecule in a second when illuminated with the photosynthetic photon flux density of 2000 μmol m?2 s?1. 相似文献
96.
Muhammad Ahsan Bashir Mohammad Al‐haj Ali Vasileios Kanellopoulos Jukka Seppälä Esa Kokko Sameer Vijay 《大分子反应工程》2013,7(5):193-204
The dependence of predictive capabilities of SL EOS on the pure characteristic parameters of monomers and polymers is investigated. A sensitivity analysis study is carried out to understand the effect of these parameters on the predictive capability of SL EOS for different α‐olefin/polyolefins systems. Among all pure component characteristic parameters, the monomer characteristic temperature (T*monomer) has the largest impact on SL EOS predictive capability; whereas the polymer characteristic density (ρ*polymer) is found to have the smallest impact.
97.
Holding pressure was expected to change the free flow of the liquid crystalline melt. Because of the complex mold used and the two variables, nozzle and mold temperature, the shear and elongational flow were in the injection molding study evaluated by means of the notched Charpy and Izod impact strength. The tensile modulus, the flexural strength and modulus mainly depended on the elongational flow induced skin. On the grounds of the microstructure composed of 4 distinct layers a free flow model of the liquid crystal polymer having a yield stress is proposed. 相似文献
98.
Dmitry Yu. Murzin Esa Toukoniitty Jan Hájek 《Reaction Kinetics and Catalysis Letters》2004,83(2):205-212
Importance of investigating catalyst deactivation in the synthesis of fine chemicals is illustrated by several examples in
three-phase hydrogenation reactions, performed in batch and continuous reactors.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
99.
100.