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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

비만아 부모의 돌봄 경험: q 방법론

Energy production and storage technologies have attracted a great deal of attention for day-to-day applications. In recent decades, advances in lithium-ion battery (LIB) technology have improved living conditions around the globe. LIBs are used in most mobile electronic devices as well as in zero-emission electronic vehicles. However, there are increasing concerns regarding load leveling of renewable energy sources and the smart grid as well as the sustainability of lithium sources due to their limited availability and consequent expected price increase. Therefore, whether LIBs alone can satisfy the rising demand for small- and/or mid-to-large-format energy storage applications remains unclear. To mitigate these issues, recent research has focused on alternative energy storage systems. Sodium-ion batteries (SIBs) are considered as the best candidate power sources because sodium is widely available and exhibits similar chemistry to that of LIBs; therefore, SIBs are promising next-generation alternatives. Recently, sodiated layer transition metal oxides, phosphates and organic compounds have been introduced as cathode materials for SIBs. Simultaneously, recent developments have been facilitated by the use of select carbonaceous materials, transition metal oxides (or sulfides), and intermetallic and organic compounds as anodes for SIBs. Apart from electrode materials, suitable electrolytes, additives, and binders are equally important for the development of practical SIBs. Despite developments in electrode materials and other components, there remain several challenges, including cell design and electrode balancing, in the application of sodium ion cells. In this article, we summarize and discuss current research on materials and propose future directions for SIBs. This will provide important insights into scientific and practical issues in the development of SIBs.

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Sodium-ion batteries: present and future

Aligned carbon-nanotube (CNT) sheets are used as building blocks to prepare light-weight, frequency-tunable and high-performance microwave absorbers, and the absorption frequency can be accurately controlled by stacking them with different intersectional angles. A remarkable reflection loss of -47.66 dB is achieved by stacking four aligned CNT sheets with an intersectional angle of 90° between two neighboring ones. The incorporation of a second phase such as a metal and a conducting polymer greatly enhances the microwave-absorption capability.

Cross-Stacking Aligned Carbon-Nanotube Films to Tune Microwave Absorption Frequencies and Increase Absorption Intensities

Energy storage systems including supercapacitors and lithium ion batteries typically appear in a rigid plate which is unfavorable for many applications, especially in the fi elds of portable and highly integrated equipments which require small size, light weight, and high fl exibility. [ 1–3 ] As a result, fl exible supercapacitors and batteries mainly in a fi lm format have been widely investigated, while wire-shaped energy storage devices are rare. [ 4 , 5 ] However, compared with the conventional planar structure, a wire device can be easily woven into textiles or other structures to exhibit unique and promising applications. The limitation is originated from the much stricter requirement for the electrode such as a combined high fl exibility and electrochemical property in wire-shaped devices. [ 6 , 7 ] It remains challenging but becomes highly desired to obtain wire-shaped supercapacitors and batteries with high performances. On the other hand, due to the unique structure and remarkable mechanical and electrical properties, carbon nanotubes (CNTs) have been widely studied as electrode materials in conventional planar energy storage devices. [ 8 , 9 ] However, CNTs are generally made in a network format in which the produced charges had to cross a lot of boundaries with low effi ciencies. It is critically important to improve the charge transport in CNT materials. [ 8–13 ]

Twisting Carbon Nanotube Fibers for Both Wire‐Shaped Micro‐Supercapacitor and Micro‐Battery

Recent advancement of nanostructured carbon for energy applications

A hollow graphene/conducting polymer composite fiber is created with high mechanical and electronic properties and used to fabricate novel fiber-shaped supercapacitors that display high energy densities and long life stability. The fiber supercapacitors can be woven into flexible powering textiles that are particularly promising for portable and wearable electronic devices.

A Fiber Supercapacitor with High Energy Density Based on Hollow Graphene/Conducting Polymer Fiber Electrode

With the booming development of flexible and wearable electronics, their safety issues and operation stabilities have attracted worldwide attentions. Compared with traditional liquid electrolytes, gel polymer electrolytes (GPEs) are preferred due to their higher safety and adaptability to the design of flexible energy storage devices. This review summarizes the recent progress of GPEs with enhanced physicochemical properties and specified functionalities for the application in electrochemical energy storage. Functional GPEs that are capable to achieve unity lithium-ion transference number and offer additional pseudocapacitance to the overall capacitance are carefully discussed. The smart GPEs with self-protection, thermotolerant, and self-healing abilities are particularly highlighted. To close, the future directions and remaining challenges of the GPEs for application in electrochemical energy storages are summarized to provide clues for the following development.

Huisheng Peng

Papers

Cross-Stacking Aligned Carbon-Nanotube Films to Tune Microwave Absorption Frequencies and Increase Absorption Intensities

Twisting Carbon Nanotube Fibers for Both Wire‐Shaped Micro‐Supercapacitor and Micro‐Battery

Recent advancement of nanostructured carbon for energy applications

A Fiber Supercapacitor with High Energy Density Based on Hollow Graphene/Conducting Polymer Fiber Electrode

Gel Polymer Electrolytes for Electrochemical Energy Storage