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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

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Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Weyl and Dirac semimetals are three-dimensional phases of matter with gapless electronic excitations that are protected by topology and symmetry. As three-dimensional analogs of graphene, they have generated much recent interest. Deep connections exist with particle physics models of relativistic chiral fermions, and, despite their gaplessness, to solid-state topological and Chern insulators. Their characteristic electronic properties lead to protected surface states and novel responses to applied electric and magnetic fields. The theoretical foundations of these phases, their proposed realizations in solid-state systems, and recent experiments on candidate materials as well as their relation to other states of matter are reviewed.

Weyl and Dirac semimetals in three-dimensional solids

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

Herein, the defect-related properties of an AlN sample prepared based on the optimal process parameters by metal nitride vapor phase epitaxy (MNVPE) were investigated. The FWHM values of the (0002)/(101̅2) planes of the sample by MNVPE are 397/422 arcsec; the advantages of similar FWHM values of (0002) and (101̅2) planes will have a huge advantage over other preparation methods such as MOCVD. From the cross-sectional TEM images of the AlN sample, it is found that the fusion of a large number of a + c type dislocations occur at the interface of the low temperature buffer layer and the epitaxial layer, which affects the growth mode of the epitaxial layer. The lower FHWM value of the E2(high) peak of the Raman spectrum, the lower the point defect concentration, which made the sample gain higher energy defect emission bands in the PL spectra and higher transmittance in the UV–vis transmission spectrum.

https://pubs.acs.org/doi/pdf/10.1021/acsomega.2c04626

Guodong Liu

Papers

Impact of Defects for AlN Single Crystal Thin Film by Metal Nitride Vapor Phase Epitaxy