다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers’ complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradat...

New Insights into Perfluorinated Sulfonic-Acid Ionomers

Due to the excellent proton conductivity of Nafion membranes in polymer electrolyte membrane fuel cells (PEMFCs), Nafion has been applied also in microbial fuel cells (MFCs). In literature, however, application of Nafion in MFCs has been associated with operational problems. Nafion transports cation species other than protons as well, and in MFCs concentrations of other cation species (Na+, K+, NH4+, Ca2+, and Mg2+) are typically 10(5) times higher than the proton concentration. The objective of this study, therefore, was to quantify membrane cation transport in an operating MFC and to evaluate the consequences of this transport for MFC application on wastewaters. We observed that during operation of an MFC mainly cation species other than protons were responsible for the transport of positive charge through the membrane, which resulted in accumulation of these cations and in increased conductivity in the cathode chamber. Furthermore, protons are consumed in the cathode reaction and, consequently, transport of cation species other than protons resulted in an increased pH in the cathode chamber and a decreased MFC performance. Membrane cation transport, therefore, needs to be considered in the development of future MFC systems.

Effects of membrane cation transport on pH and microbial fuel cell performance.

Selectivity of ion exchange membranes: A review

Ion mobility in Nafion-117 membranes

Membranes are widely used in modern technology. The demand for different types of membranes and membrane processes is increasing every year. This review summarizes the current state of the art and prospects of membrane science developments including membrane materials for gas separation, pervaporation, and pressure-driven membrane processes; ion-exchange, hybrid, and track-etched membranes; membranes for electrochemical sensors; and mathematical modeling of membrane separation processes and ion and water transport in membrane systems. Studies aimed at improving the selectivity and performance of membranes and their stability are surveyed. New approaches to the synthesis and modification of membranes as well as their advanced applications are discussed.

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Prospects of Membrane Science Development

In this review, modern notions on the structure and properties of one of the most in-demand classes of nanomaterials—ion-exchange membranes—are generalized. Data are presented on their transport properties, on their use in electrodialysis and in alternative power engineering, on the methods of their modification that lead to changing the conducting and selective properties of membranes, and on certain aspects of their use in modern technologies.

Ion-Exchange Membrane Materials: Properties, Modification, and Practical Application

State-of-the-art in the studies of sodium-ion batteries is discussed in comparison with their deeper developed lithium-ion analogs. The principal problem hindering the development of competitive sodium-ion batteries is the low effectiveness of the electrode materials at hand. The principal efforts in the formation of anodes for the sodium-ion batteries are reduced to the development of materials based on carbon, metals, alloys, and transition metal oxides. Cathode materials are searched among oxides (first of all, layered) and salt systems. Synthesis of electrolytes for the sodium-ion batteries is not sufficiently attended to. Nowadays it is sodium salt solutions in organic solvents that are dominated; however, polymer and solid electrolytes with sodium conductivity may be thought of as very perspective. Reference list contains 584 items.

Sodium-Ion Batteries (a Review)

The state-of-the-art in the field of cathode and anode nanomaterials for lithium-ion batteries is considered. The use of these nanomaterials provides higher charge and discharge rates, reduces the adverse effect of degradation processes caused by volume variations in electrode materials upon lithium intercalation and deintercalation and enhances the power and working capacity of lithium-ion batteries. In discussing the cathode materials, attention is focused on double phosphates and silicates of lithium and transition metals and also on vanadium oxides. The anode materials based on nanodispersions of carbon, silicon, certain metals, oxides and on nanocomposites are also described. The bibliography includes 714 references.

https://iopscience.iop.org/article/10.1070/RCR4497/pdf

A. B. Yaroslavtsev

Papers

Ion mobility in Nafion-117 membranes

Prospects of Membrane Science Development

Ion-Exchange Membrane Materials: Properties, Modification, and Practical Application

Sodium-Ion Batteries (a Review)

Electrode nanomaterials for lithium-ion batteries