There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

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A review of electrode materials for electrochemical supercapacitors

1. Introduction 20642. Synthesis of Magnetic Nanoparticles 20662.1. Classical Synthesis by Coprecipitation 20662.2. Reactions in Constrained Environments 20682.3. Hydrothermal and High-TemperatureReactions20692.4. Sol-Gel Reactions 20702.5. Polyol Methods 20712.6. Flow Injection Syntheses 20712.7. Electrochemical Methods 20712.8. Aerosol/Vapor Methods 20712.9. Sonolysis 20723. Stabilization of Magnetic Particles 20723.1. Monomeric Stabilizers 20723.1.1. Carboxylates 20733.1.2. Phosphates 20733.2. Inorganic Materials 20733.2.1. Silica 20733.2.2. Gold 20743.3. Polymer Stabilizers 20743.3.1. Dextran 20743.3.2. Polyethylene Glycol (PEG) 20753.3.3. Polyvinyl Alcohol (PVA) 20753.3.4. Alginate 20753.3.5. Chitosan 20753.3.6. Other Polymers 20753.4. Other Strategies for Stabilization 20764. Methods of Vectorization of the Particles 20765. Structural and Physicochemical Characterization 20785.1. Size, Polydispersity, Shape, and SurfaceCharacterization20795.2. Structure of Ferro- or FerrimagneticNanoparticles20805.2.1. Ferro- and Ferrimagnetic Nanoparticles 20805.3. Use of Nanoparticles as Contrast Agents forMRI20825.3.1. High Anisotropy Model 20845.3.2. Small Crystal and Low Anisotropy EnergyLimit20855.3.3. Practical Interests of Magnetic NuclearRelaxation for the Characterization ofSuperparamagnetic Colloid20855.3.4. Relaxation of Agglomerated Systems 20856. Applications 20866.1. MRI: Cellular Labeling, Molecular Imaging(Inﬂammation, Apoptose, etc.)20866.2.

Magnetic Iron Oxide Nanoparticles: Synthesis, Stabilization, Vectorization, Physicochemical Characterizations, and Biological Applications

[Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Cheng, HM (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, 72 Wenhua Rd, Shenyang 110016, Peoples R China;cheng@imr.ac.cn

Advanced Materials for Energy Storage

Manganese (Mn)-doped silicon nanocrystals (Si NCs) in which Mn is in its most likely substitutional or interstitial location have been investigated. Large differences in magnetic moment are found between Si NCs doped with substitutional Mn and those doped with interstitial Mn. For all the doped Si NCs, quantum confinement affects the electronic states of majority spin more significantly than those of minority spin. As the NC size changes from 1.2 to 1.5 nm, the spin flipping of electronic transition across the NC optical gap occurs for Si NCs doped with substitutional Mn. This leads to significant changes in the optical absorption of Si NCs. It is likely that such spin-flipping also happens for larger (>1.7 nm) Si NCs doped with interstitial Mn.

Silicon nanocrystals doped with substitutional or interstitial manganese

In this paper, we investigate oxidation-induced stacking faults (OSFs) and related grown-in oxygen precipitates of nitrogen-doped Czochralski (NCZ) silicon. The samples were oxidized at 1150 °C or were annealed under different conditions. It was found that OSFs with different densities in the NCZ silicon distributed not only in the OSF-ring region, but also in the inner region of the ring. Furthermore, the OSF ring was extended by nitrogen doping. In addition, the investigation of oxygen precipitates indicates that nitrogen changes the size and density distribution of grown-in oxygen precipitates in the OSF-ring and void regions of the NCZ silicon during crystal growth, and therefore the OSF behaviour is changed. Based on the experimental facts, in particular we discuss the mechanism of nitrogen affecting the distribution of OSFs in different regions.

https://iopscience.iop.org/article/10.1088/0268-1242/18/4/334/pdf

Oxidation-induced stacking faults and related grown-in oxygen precipitates in nitrogen-doped Czochralski silicon

Silicon is regarded as the next-generation alternative anode material of lithium–ion battery due to the highest theoretical specific capacity of 4200 mAh g−1. Nevertheless, the drastic volume expansion/shrink (~ 300%) during the lithiation/delithiation process and the poor electrical conductivity obstruct its commercial application. Herein, we report a novel design of litchi-structural Si@C nanoparticles (L-S Si@C) as long cycle life anode material for lithium–ion battery. The L-S Si@C with nanosized (~ 50 nm) SiC dispersed in the inner surface and ~ 6 wt% carbon layer covering the outer surface delivers a specific capacity of 1145 mAh g−1 in the initial cycle and maintains a specific capacity of 570 mAh g−1 after 300th cycling times, which can be attributed to the specially structurally stable L-S Si@C nanoparticles.

Deren Yang

Papers

Silicon nanocrystals doped with substitutional or interstitial manganese

Oxidation-induced stacking faults and related grown-in oxygen precipitates in nitrogen-doped Czochralski silicon

Litchi-structural core–shell Si@C for high-performance lithium–ion battery anodes

Impact of carbon co-doping on the performance of crystalline silicon solar cells

The structural evolution of nanocrystalline diamond films synthesized by r.f. PECVD