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

Metal-free electrochemical catalysts for oxygen reduction reaction

The subsolidus phase relations of the Cu-Ga-N system are studied by X-ray powder diffraction. The phase relations of the binary Cu-Ga system are checked firstly. theta-CuGa2 which belongs to the tetragonal system is determined to be a stoichiometric compound and its thermal expansion is measured by temperature-dependent X-ray powder diffraction from 93 to 523 K. The linear temperature dependences of the expansion coefficients along the a- and c-axis and volume coefficients are obtained, Cea = (1.97349 - 3.84678 x 10(-5)T) x 10(-5), a, = (2.00261 - 3.96007 x 10(-5)T) x 10(-5) and av = (6.01498 - 3.49098 x 10(-4)T) x 10(-5), respectively. No ternary compound is found in the Cu-Ga-N system. Cu and its alloys could have some reaction with GaN under the present experimental condition. (C) 2006 Elsevier B.V. All rights reserved.

Subsolidus Phase Relations of the Cu—Ga—N System.

The phase diagram of the Ag-Ga binary system and the phase relations of the Ag-Ga-N system are studied by DTA and X-ray powder diffraction. The equilibrium phase diagram of the Ag-Ga system is reconstructed. Two intermetallic phases are determined in the Ag-Ga system: the Ag2Ga compound and a novel delta-Ag3Ga2 with the composition about 40 at.% Ga. The novel phase delta-Ag3Ga2 which is the product of the peritectic reaction Ag2Ga + L delta-Ag3Ga2 at 575 K is indexed with an orthorhomic lattice with lattice parameters a = 6.7276(2) angstrom, b = 3.8840(1) angstrom, c = 3.2200(1) angstrom and V = 84.14 angstrom(3). The temperature-dependent lattice parameters of zeta'-Ag2Ga with 28 at.% Ga are measured by temperature-dependent X-ray powder diffraction from 93 to 543 K. The linear temperature dependences of the expansion coefficients along the direction of a- and c-axis and volume coefficients are obtained, alpha(a) = (1.4741 + 0.0028 T) x 10(-5), alpha(c) = (1.1710 + 9.1349 x 10(-4) T) x 10(-5) and alpha(V) = (4.1167 + 0.0065 T ) x 10(-5), respectively. No ternary phase is found in the Ag-Ga-N system and no solubility of Ag in GaN is observed under the present experimental conditions. (c) 2006 Elsevier B.V. All rights reserved.

Phase Relations of the Ag—Ga—N System.

Synthesis and electrochemical properties of a new compound, Na0.8Li0.1Ni0.31Mn0.62O2

The isothermal section at 700 degrees C in the Co-rich ternary Sm-Co-B system was determined by means of X-ray diffraction. In this range, nine ternary borides were observed: Sm3Co13B2, SmCo4B, Sm3Co11B4, Sm2Co7B3, SmCo3B2, Sm2Co14B, SmCo12B6, SmCo4B4, SmCo2B2. The first five borides are members of the homologous series Smm + nCo5m + 3nB2n formed by alternative stacking m layers of SmCo5 with n layers of SmCo3B2 along the c-axis. The compound Sm3Co13B2 was not reported in previous isothermal sections found in the literature. (C) 2000 Elsevier Science S.A. All rights reserved.

Ji Liang

Papers

Metal-free electrochemical catalysts for oxygen reduction reaction

Subsolidus Phase Relations of the Cu—Ga—N System.

Phase Relations of the Ag—Ga—N System.

Synthesis and electrochemical properties of a new compound, Na0.8Li0.1Ni0.31Mn0.62O2

Phase Relation in the System Sm—Co—B.