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

Magnetic and structural properties of ErMn6Sn6-xGax (x=0-2.0) with the HfFe6Ge6-type structure have been investigated. The compounds (x=0.2-2.0) are characterized by ferrimagnetic ordering, and Curie temperatures increase from 75 K for x=0 to 383 K for x=0.4 and then decrease to 288 K for x=2.0, which are due to the contraction of the unit cell and the decrease of conduction-electron density with Ga substitution. The compounds (x=0.2-2.0) display large coercive fields (0.73less than or equal tomu(0 i)H(c)less than or equal to2.2 T) at 5 K. The sign of the second-order crystalline electric-field (CEF) coefficient A(2)(0) of the Er sublattice reverses by a small amount of Ga substitution for Sn. Moreover, the fourth-order CEF coefficient A(4)(0) of the Er sublattice and sixth-order Stevens factor gamma(J) are proved to play important roles in the determination of the easy magnetic direction.

Structural and magnetic properties of HfFe 6 Ge 6 -type ErMn 6 Sn 6 − x Ga x ( x = 0 – 2 . 0 ) compounds

Doping enables the effective tuning of the properties of semiconductor nanocrystals (NCs). In this paper, germanium (Ge) NCs are doped with boron (B) in nonthermal plasma. It is shown that B atoms prefer residing at/near the NC surface, rather than in the NC core. The surface state of Ge NCs is modified by the B doping. The oxidation of B-doped Ge NCs is not as serious as that of undoped Ge NCs. Devices based on B-doped Ge-NC films cast from the dispersion of B-doped Ge NCs have been fabricated. It is shown that the electrical conduction of the B-doped Ge-NC films is closely related to the doping level of B.

Nonthermal Plasma Synthesized Boron-Doped Germanium Nanocrystals

The optical properties of reactive co-sputtered erbium doped silicon rich oxynitride (Er:SRON) films are studied as a function of annealing temperatures (Ta). The sensitization mechanism of Er3+ is found to evolve with Ta: excess Si related localized states play the essential role in samples when Ta is below 700 °C, while silicon nanoclusters (Si-NCs) become the dominate sensitizers when Ta exceeds 800 °C. Our results show that higher density of sensitized Er3+ could be acquired via energy transfer from localized states, and thus provide an alternative way for the engineering of light sources based on Er:SRON.

Sensitization of Er 3+ ions in silicon rich oxynitride films: effect of thermal treatments

The shallow thermal donors (STDs) in silicon doped with isotopic oxygen 16 O and 18 O have been investigated. The sample annealed at 1275°C for 4 h in a nitrogen ambient was measured by a Fourier transform infrared (FTIR) spectrometer at 10 K. In comparison, a nitrogen doped Czochralski (NCZ) silicon sample in which nitrogen–oxygen complexes existed was also checked by the FTIR spectrometer. It was found that STDs were formed in the oxygen isotope doped silicon during annealing at high temperature. It is considered that nitrogen could be involved in the generation of STDs. The line positions of the STDs were almost the same as that of the N–O complexes in NCZ silicon. The small shift of some absorption lines of STDs was also observed. In addition, a new unidentified shallow center was found and discussed.

Shallow thermal donors in silicon doped with isotopic oxygen

In this paper, the effect of annealing atmosphere on oxygen precipitation and formation of denuded zone (DZ) in Czochralski (CZ) silicon has been investigated. It was revealed that the high-temperature annealings in various atmospheres resulted in almost identical oxygen outdiffusion length but different widths of DZ in the silicon wafers. It was confirmed that the high-temperature annealing in nitrogen atmosphere induced a high concentration of vacancies in silicon to enhance oxygen precipitation, while the annealing in oxidizing atmosphere or steam-mixed atmosphere induced a high concentration of silicon self-interstitials to retard oxygen precipitation. Moreover, it was confirmed that the steam mixed into the nitrogen atmosphere could suppress the indiffusion of nitrogen atoms. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Deren Yang

Papers

Structural and magnetic properties of HfFe 6 Ge 6 -type ErMn 6 Sn 6 − x Ga x ( x = 0 – 2 . 0 ) compounds

Nonthermal Plasma Synthesized Boron-Doped Germanium Nanocrystals

Sensitization of Er 3+ ions in silicon rich oxynitride films: effect of thermal treatments

Shallow thermal donors in silicon doped with isotopic oxygen

Effect of annealing atmosphere on oxygen precipitation and formation of denuded zone in Czochralski silicon wafer