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

Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.

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Carbon capture and storage (CCS): the way forward

Ultrathin, lightweight, and flexible electromagnetic-interference (EMI) shielding materials are urgently required to manage increasingly serious radiation pollution. 2D transition-metal carbides (MXenes) are considered promising alternatives to graphene for providing excellent EMI-shielding performance due to their outstanding metallic electrical conductivity. However, the hydrophilicity of MXene films may affect their stability and reliability when applied in moist or wet environments. Herein, for the first time, an efficient and facile approach is reported to fabricate freestanding, flexible, and hydrophobic MXene foam with reasonable strength by assembling MXene sheets into films followed by a hydrazine-induced foaming process. In striking contrast to well-known hydrophilic MXene materials, the MXene foams surprisingly exhibit hydrophobic surfaces and outstanding water resistance and durability. More interestingly, a much enhanced EMI-shielding effectiveness of ≈70 dB is achieved for the lightweight MXene foam as compared to its unfoamed film counterpart (53 dB) due to the highly efficient wave attenuation in the favorable porous structure. Therefore, the hydrophobic, flexible, and lightweight MXene foam with an excellent EMI-shielding performance is highly promising for applications in aerospace and portable and wearable smart electronics.

Hydrophobic, Flexible, and Lightweight MXene Foams for High-Performance Electromagnetic-Interference Shielding

Transition metal carbides and nitrides (MXenes), a family of two-dimensional (2D) inorganic compounds, are materials composed of a few atomic layers of transition metal carbides, nitrides, or carbonitrides. Ti3C2, the first 2D layered MXene, was isolated in 2011. This material, which is a layered bulk material analogous to graphite, was derived from its 3D phase, Ti3AlC2 MAX. Since then, material scientists have either determined or predicted the stable phases of >200 different MXenes based on combinations of various transition metals such as Ti, Mo, V, Cr, and their alloys with C and N. Extensive experimental and theoretical studies have shown their exciting potential for energy conversion and electrochemical storage. To this end, we comprehensively summarize the current advances in MXene research. We begin by reviewing the structure types and morphologies and their fabrication routes. The review then discusses the mechanical, electrical, optical, and electrochemical properties of MXenes. The focus then turns to their exciting potential in energy storage and conversion. Energy storage applications include electrodes in rechargeable lithium- and sodium-ion batteries, lithium-sulfur batteries, and supercapacitors. In terms of energy conversion, photocatalytic fuel production, such as hydrogen evolution from water splitting, and carbon dioxide reduction are presented. The potential of MXenes for the photocatalytic degradation of organic pollutants in water, such as dye waste, is also addressed, along with their promise as catalysts for ammonium synthesis from nitrogen. Finally, their application potential is summarized.

Applications of 2D MXenes in energy conversion and storage systems

MXene, a new series of 2D material, has been steadily advancing its applications to a variety of fields, such as catalysis, supercapacitor, molecular separation, electromagnetic wave interference shielding. This work reports a carefully designed aqueous droplet light heating system along with a thorough mathematical procedure, which combined leads to a precise determination of internal light-to-heat conversion efficiency of a variety of nanomaterials. The internal light-to-heat conversion efficiency of MXene, more specifically Ti3C2, was measured to be 100%, indicating a perfect energy conversion. Furthermore, a self-floating MXene thin membrane was prepared by simple vacuum filtration and the membrane, in the presence of a rationally chosen heat barrier, produced a light-to-water-evaporation efficiency of 84% under one sun irradiation, which is among the state of art energy efficiency for similar photothermal evaporation system. The outstanding internal light-to-heat conversion efficiency and great light...

MXene Ti3C2: An Effective 2D Light-to-Heat Conversion Material

Two-dimensional (2D) materials are promising candidates for advanced water purification membranes. A new kind of lamellar membrane is based on a stack of 2D MXene nanosheets. Starting from compact Ti3AlC2, delaminated nanosheets of the composition Ti3C2Tx with the functional groups T (O, OH, and/or F) can be produced by etching and ultrasonication and stapled on a porous support by vacuum filtration. The MXene membrane supported on anodic aluminum oxide (AAO) substrate shows excellent water permeance (more than 1000 L m−2 h−1 bar−1) and favorable rejection rate (over 90 %) for molecules with sizes larger than 2.5 nm. The water permeance through the MXene membrane is much higher than that of the most membranes with similar rejections. Long-time operation also reveals the outstanding stability of the MXene membrane for water purification.

A Two-Dimensional Lamellar Membrane: MXene Nanosheet Stacks

Molecular sieving membranes with sufficient and uniform nanochannels that break the permeability-selectivity trade-off are desirable for energy-efficient gas separation, and the arising two-dimensional (2D) materials provide new routes for membrane development. However, for 2D lamellar membranes, disordered interlayer nanochannels for mass transport are usually formed between randomly stacked neighboring nanosheets, which is obstructive for highly efficient separation. Therefore, manufacturing lamellar membranes with highly ordered nanochannel structures for fast and precise molecular sieving is still challenging. Here, we report on lamellar stacked MXene membranes with aligned and regular subnanometer channels, taking advantage of the abundant surface-terminating groups on the MXene nanosheets, which exhibit excellent gas separation performance with H2 permeability >2200 Barrer and H2/CO2 selectivity >160, superior to the state-of-the-art membranes. The results of molecular dynamics simulations quantitatively support the experiments, confirming the subnanometer interlayer spacing between the neighboring MXene nanosheets as molecular sieving channels for gas separation. Two-dimensional materials show great potential for membrane technologies, but their disordered channels hinder their molecular sieving performance. Here, Wang, Gogotsi and colleagues design a MXene membrane with ordered nanochannels that exhibits an excellent H2/CO2 gas separation performance.

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MXene molecular sieving membranes for highly efficient gas separation.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.201813331

Inside Cover: Ultra-Tuning of the Aperture Size in Stiffened ZIF-8_Cm Frameworks with Mixed-Linker Strategy for Enhanced CO2/CH4 Separation (Angew. Chem. Int. Ed. 1/2019)

Traditional ways of producing drinking water from groundwater, water recycling and water conservation are not sufficient. Seawater desalination would close the gap but the main technology used is thermally driven multi-flash distillation, which is energy consuming and not sustainable. Stacking two-dimensional (2D) nanomaterials into lamellar membranes is a promising technique in the pursuit of both high selectivity and permeance in water desalination. However, 2D membranes tend to swell in water, and increasing their stability in aqueous solution is still challenging. Here, we report non-swelling, MXene membranes prepared by the intercalation of Al3+ ions. Swelling is prevented by strong interactions between Al3+ and oxygen functional groups terminating at the MXene surface. These membranes show excellent non-swelling stability in aqueous solutions up to 400 h and possess high rejection of NaCl (~89.5–99.6%) with fast water fluxes (~1.1–8.5 l m−2 h−1). Such membranes can be easily fabricated by simple filtration and ion-intercalating methods, which holds promise for their scalability. Two-dimensional lamellar membranes for water purification are promising but suffer from swelling that reduces their ion sieving performance in water. This study reports easy-to-fabricate, non-swelling MXene membranes prepared by the intercalation of Al3+ ions that could be scalable.

Effective ion sieving with Ti 3 C 2 T x MXene membranes for production of drinking water from seawater

Two-dimensional (2D) graphitic carbon nitride (g-C3 N4 ) nanosheets show brilliant application potential in numerous fields. Herein, a membrane with artificial nanopores and self-supporting spacers was fabricated by assembly of 2D g-C3 N4 nanosheets in a stack with elaborate structures. In water purification the g-C3 N4 membrane shows a better separation performance than commercial membranes. The g-C3 N4 membrane has a water permeance of 29 L m-2 h-1 bar-1 and a rejection rate of 87 % for 3 nm molecules with a membrane thickness of 160 nm. The artificial nanopores in the g-C3 N4 nanosheets and the spacers between the partially exfoliated g-C3 N4 nanosheets provide nanochannels for water transport while bigger molecules are retained. The self-supported nanochannels in the g-C3 N4 membrane are very stable and rigid enough to resist environmental challenges, such as changes to pH and pressure conditions. Permeation experiments and molecular dynamics simulations indicate that a novel nanofluidics phenomenon takes place, whereby water transport through the g-C3 N4 nanosheet membrane occurs with ultralow friction. The findings provide new understanding of fluidics in nanochannels and illuminate a fabrication method by which rigid nanochannels may be obtained for applications in complex or harsh environments.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ange.201783161

Yanying Wei

Papers

A Two-Dimensional Lamellar Membrane: MXene Nanosheet Stacks

MXene molecular sieving membranes for highly efficient gas separation.

Inside Cover: Ultra-Tuning of the Aperture Size in Stiffened ZIF-8_Cm Frameworks with Mixed-Linker Strategy for Enhanced CO2/CH4 Separation (Angew. Chem. Int. Ed. 1/2019)

Effective ion sieving with Ti 3 C 2 T x MXene membranes for production of drinking water from seawater

Water Transport with Ultralow Friction through Partially Exfoliated g-C 3 N 4 Nanosheet Membranes with Self-Supporting Spacers