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

The chemistry of graphene oxide is discussed in this critical review Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene-like materials, is also discussed This review will be of value to synthetic chemists interested in this emerging field of materials science, as well as those investigating applications of graphene who would find a more thorough treatment of the chemistry of graphene oxide useful in understanding the scope and limitations of current approaches which utilize this material (91 references)

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The chemistry of graphene oxide

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

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Carbon Nanotubes: Present and Future Commercial Applications

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Every few years, a new material with unique properties emerges and fascinates the scientific community, typical recent examples being high-temperature superconductors and carbon nanotubes. Graphene is the latest sensation with unusual properties, such as half-integer quantum Hall effect and ballistic electron transport. This two-dimensional material which is the parent of all graphitic carbon forms is strictly expected to comprise a single layer, but there is considerable interest in investigating two-layer and few-layer graphenes as well. Synthesis and characterization of graphenes pose challenges, but there has been considerable progress in the last year or so. Herein, we present the status of graphene research which includes aspects related to synthesis, characterization, structure, and properties.

Graphene: The New Two-Dimensional Nanomaterial

Since their discovery, carbon nanotubes have attracted the attention of many a scientist around the world. This extraordinary interest stems from their outstanding structural, mechanical, and electronic properties. In fact, apart from being the best and most easily available one-dimensional (1D) model system, carbon nanotubes show strong application potential in electronics, scanning probe microscopy, chemical and biological sensing, reinforced composite materials, and in many more areas. While some of the proposed applications remain still a far-off dream, others are close to technical realization. Recent advances in the development of reliable methods for the chemical functionalization of the nanotubes provide an additional impetus towards extending the scope of their application spectrum. In particular, covalent modification schemes allow persistent alteration of the electronic properties of the tubes, as well as to chemically tailor their surface properties, whereby new functions can be implemented that cannot otherwise be acquired by pristine nanotubes.

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Chemically functionalized carbon nanotubes.

Electrical transport studies on graphene have been focused mainly on the linear dispersion region around the Fermi level and, in particular, on the effects associated with the quasiparticles in graphene behaving as relativistic particles known as Dirac fermions. However, some theoretical work has suggested that several features of electron transport in graphene are better described by conventional semiconductor physics. Here we use scanning photocurrent microscopy to explore the impact of electrical contacts and sheet edges on charge transport through graphene devices. The photocurrent distribution reveals the presence of potential steps that act as transport barriers at the metal contacts. Modulations in the electrical potential within the graphene sheets are also observed. Moreover, we find that the transition from the p- to n-type regime induced by electrostatic gating does not occur homogeneously within the sheets. Instead, at low carrier densities we observe the formation of p-type conducting edges surrounding a central n-type channel.

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Contact and edge effects in graphene devices

Carbon nanotubes (CNTs) exhibit a unique combination of excellent mechanical, electrical and electrochemical properties, which has stimulated increasing interest in the application of CNTs as components in (bio)sensors. This review highlights various design methodologies for CNT-based biosensors and their employment for the detection of a number of biomolecules. In addition, recent developments in the fields of CNT-based chemiresistors and chemically sensitive field-effect transistors are presented. After a critical discussion of the factors that currently limit the practical use of CNT-based biosensors, the review concludes with an outline of potential future applications for CNTs in biology and medicine.

Biosensors based on carbon nanotubes

Nanoparticles on an atomic carpet: Individual graphene sheets have been decorated with metal nanoparticles through electrochemistry. The attachment of Pd particles onto graphene renders it sensitive to hydrogen. The controlled functionalization of graphene paves the way for various electronic applications.

Electrochemical Modification of Graphene

Photoconductivity in individual semiconducting single-wall carbon nanotubes was investigated using a confocal scanning optical microscope. The magnitude of the photocurrent was found to increase linearly with the laser intensity, and to be maximum for parallel orientation between the light polarization and the tube axis. Larger currents were obtained upon illuminating the tubes at 514.5 nm in comparison to those at 647.1 nm, consistent with the semiconducting tubes having a resonant absorption energy at the former wavelength. Moreover, the determination of the photoresponse as a function of position along single nanotubes has proven to be a useful tool to monitor local electronic structure effects.

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Kannan Balasubramanian

Papers

Chemically functionalized carbon nanotubes.

Contact and edge effects in graphene devices

Biosensors based on carbon nanotubes

Electrochemical Modification of Graphene

Photoelectronic transport imaging of individual semiconducting carbon nanotubes