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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication.

Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions

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

Dual-modification of manganese oxide by heterostructure and cation pre-intercalation for high-rate and stable zinc-ion storage

F insertion into the lattice of copper oxides Pr 2−x Sr x CuO 4−y (x=0.0, 0.4, 1.0) is accomplished by the low temperature fluorination reaction. No SrF 2 was detected in the fluorinated products. F doping successfully induced superconductivity in PrSrCu(O,F) 4-δ (T c =15K), but failed to optimize carries density and induce superconductivity in Pr 2 CuO 4−x F x and Pr 1.6 Sr 0.4 CuO 4−x F x .

Synthesis and superconductivity of fluorides of Pr2-xSrxCuO4-y (x=0.0, 0.4, 1.0)

The worldwide demand for green and renewable energy resources as well as the development of electronic devices has greatly boosted the improvement of energy storage systems. As one of the major types of energy storage devices, supercapacitors, with ultrahigh power densities, long-term cycling lives, and rapid charge and discharge capabilities, have been extensively investigated at the current stage, especially for those flexible or wearable electronic devices, which could be integrated into a smart system. In this chapter, the basic structures, the energy storage mechanisms, the categorization, and the characteristics of supercapacitors are comprehensively discussed. This chapter mainly focuses on different major components of flexible supercapacitors, ranging from the flexible electrode structure, the flexible substrates, and the improved electrolyte, to the construction of self-responsive flexible devices. Meanwhile, the emerging flexible integrated systems with these devices have also been illustrated, such as the energy sensor integrated systems and the energy collection-storage-sensing systems. Furthermore, the future trend of flexible supercapacitors based on future demands will be lastly discussed, focusing on the feasible and efficient strategies for designing novel and high-performance supercapacitors in future research.

Self-responsive Nanomaterials for Flexible Supercapacitors

A new compound, Na2Zn5(PO4)(4), was identified in the system ZnO-Na2O-P2O5 and high-quality crystal was obtained by the melt method. The crystal structure of this compound was solved by direct method from single crystal X-ray diffraction data. The structure was then refined anisotropically using a full-matrix least square refinement on F-2 and the refinement converged to R-1 = 0.0233 and wR(2) = 0.0544. This compound crystallizes in the orthorhombic system with space group Pbcn, lattice parameters a=10.381(2) angstrom, b=8.507(1) angstrom, c = 16.568(3) angstrom and Z = 4. The structure is made up of 3D [Zn5P4O16](n)(2n-) covalent framework consisting of [Zn4P4O16](n)(4n-) layers. The powder diffraction pattern of Na9Zn21(PO4)(17) is explained by simulating a theoretical pattern with NaZnPO4 and Na2Zn5(PO4)(4) in the molar ratio of 1:4 and then by Rietveld refinement of experimental pattern. Na2Zn5(PO4)(4) melts congruently at 855 degrees C and its conductivity is 5.63 x 10(-9) S/cm. (C) 2007 Elsevier Inc. All rights reserved.

Ji Liang

Papers

Dual-modification of manganese oxide by heterostructure and cation pre-intercalation for high-rate and stable zinc-ion storage

Synthesis and superconductivity of fluorides of Pr2-xSrxCuO4-y (x=0.0, 0.4, 1.0)

Self-responsive Nanomaterials for Flexible Supercapacitors

A New Structure Type of Phosphate: Crystal Structure of Na2Zn5(PO4)4.