How does the proton exchange membrane function in fuel cells?4 answersThe proton exchange membrane (PEM) in fuel cells plays a crucial role in facilitating the conversion of chemical energy to electricity. It acts as an electrolyte, allowing protons to move from the anode to the cathode while blocking the passage of gases like hydrogen and oxygen. The membrane must possess specific characteristics such as high proton transport, good electrical insulation, low fuel permeability, and excellent thermal and chemical stability to enhance fuel cell efficiency. Various materials like Nafion, graphene oxide composites, and nanocomposites are used to create PEMs with improved properties like high conductivity, thermal stability, and resistance to dehydration or flooding. Understanding and optimizing the PEM structure and properties are essential for enhancing fuel cell performance, longevity, and cost-effectiveness.
What is ptaas?5 answersA Polynomial Time Approximation Scheme (PTAS) is a method used to efficiently approximate solutions to computationally complex optimization problems within a polynomial time frame. PTASes have been developed for various challenging problems across different domains. In the context of research papers provided, PTASes have been proposed for a range of problems such as the unit demand capacitated vehicle routing problem on trees and splittable CVRP, clustering problems with different center types, unsplittable flow on a path problem, rectangle stabbing problems including horizontal and general rectangle stabbing, and constraint satisfaction problems on sparse graph classes. These PTASes offer efficient approximation algorithms for these NP-hard problems, enabling practical solutions with guaranteed performance bounds.
What is the effect of Pt nanowires on the performance and durability of fuel cells?5 answersPt nanowires have not been specifically mentioned in the abstracts provided. Therefore, there is no information available on the effect of Pt nanowires on the performance and durability of fuel cells.
What is the history of fuel cells?5 answersFuel cells have a long history, dating back to 1839 when Sir William Groves demonstrated his "gaseous voltaic battery". However, despite their early development, fuel cells remained in their technological infancy until recently. Intensive development for the space program in the 1960s and further development in automotive applications since the 1990s have contributed to the progress of fuel cell technology. Fuel cells have been gradually progressing with intense research in various fields, such as material engineering and nanotechnology. Over the years, fuel cells have found applications in power sources for buses, automobiles, central utility power plants, and even small electronic devices. Despite successful development of different types of fuel cells, commercialization has remained limited to niche applications. The history of fuel cells highlights the technical challenges faced by developers and the potential for present research to benefit from past experiences.
What is PTLD?5 answersPosttransplant lymphoproliferative disorder (PTLD) is a heterogeneous group of lymphoproliferative diseases that occur in the setting of immunosuppression following hematopoietic stem cell transplant and solid organ transplantation. PTLD is a serious complication with a high mortality rate in transplant recipients. It is important to establish personalized risk evaluation for PTLD development based on Epstein-Barr virus serostatus and viral load. Different therapeutic approaches have been used to treat PTLD, including reduction in immunosuppression, surgery, cytotoxic chemotherapy, immunotherapy, anti-viral agents, and radiation. New therapeutic strategies based on the administration of virus-specific cytotoxic T cells have also been developed. PTLD is predominantly associated with B-cell origin and Epstein-Barr virus infection. EBV serological status is considered an important risk factor for PTLD. Treatment with surgery alone is associated with improved outcomes in cases of polymorphic PTLD.
What are the main applications of fuel cells?2 answersFuel cells have various applications in different sectors. In the transportation sector, fuel cells can be used in passenger cars, buses, lorries, bicycles, forklifts, trains, ships, and airplanes. They can also be used in the building sector to provide heat and power for buildings, replacing current fossil fuel systems. Fuel cells can be used for portable energy requirements, offering longer periods of autonomy compared to battery-operated equipment. Additionally, fuel cells can be integrated into extended electricity networks to supply power to regions or nations. In terms of fuel cell types, there are several options including alkaline fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, direct methanol fuel cells, proton exchange membrane fuel cells, solid oxide fuel cells, and microbial fuel cells.