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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

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

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

The richness of optical and electronic properties of graphene attracts enormous interest. Graphene has high mobility and optical transparency, in addition to flexibility, robustness and environmental stability. So far, the main focus has been on fundamental physics and electronic devices. However, we believe its true potential lies in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited, even in the absence of a bandgap, and the linear dispersion of the Dirac electrons enables ultrawideband tunability. The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light-emitting devices to touch screens, photodetectors and ultrafast lasers. Here we review the state-of-the-art in this emerging field.

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Graphene photonics and optoelectronics

Reply to 'Do thermal effects cause the propulsion of bulk graphene material?'

The invention relates to a monolayer graphite oxide and water-soluble polymer reinforced composite material and a preparation method thereof. The preparation method comprises a concrete step of filling a water-soluble polymer matrix with monolayer graphite oxide material, wherein the weight proportion is 0.1 to 20 percent of the monolayer graphite oxide and 99.9 to 80 percent of the water-soluble polymer matrix material. The preparation method is characterized by utilizing the excellent mechanical properties, large length-diameter ratio and good water dispersity of the monolayer graphite oxide to prepare the reinforced water-soluble polymer composite material. As a solvent used in the process of preparing the composite material is mainly water, the preparation method is friendly to environment, simple in process and easy to popularize and apply.

Mono-layer graphite oxide and water-soluble high molecule reinforced compound material

Althoughmatrix-assisted laser desorption/ionization (MALDI) has been widely applied as a method of soft ionization, it has also been found that reduction is an inherent feature accompanying this process. Using matrices of 2,5-dihydroxybenzoic acid (DHB) and nicotinic acid, Zhang et al. found that copper(II) ions were reduced by gas-phase charge exchange with matrix molecules. In addition, the reduction was further enhanced by free electron capture in the gas phase. The redox behaviour of some dye molecules and their derivatives has also been studied. Other examples, such as riboflavin, have also been reported. Riboflavin, also known as vitamin B2, is the central component of flavin-adenine dinucleotide and flavin mononucleotide. Due to its important biological role in energy metabolism, it has been studied and analyzed with MALDI mass spectrometry (MS) by several groups. Itoh et al. found that the flavin-containing compounds were reduced by both processes, fast atom bombardment and MALDI. As shown in Scheme 1, the reduction of riboflavin in MALDI is believed to be a result of the transfer of protons and electrons from the matrix or target to the riboflavin. It is well known that oxidation-reduction reactions play critical roles in biochemical processes. Understanding the various reduction states of redox-sensitive molecules in the process of metabolism is vitally important. However, due to the accompanying reduction in the ionization process, MALDI results cannot be used directly to judge the reduction states of related biosamples. Different methods have been tried in order to solve this problem. Okuno et al. found that, even without a matrix, riboflavin was also reduced in the process of desorption/ionization on porous silicon (DIOS). Tajiri et al. studied the MALDI mass spectra of methylene blue and riboflavin using both a UV laser at 337 nm with a DHB matrix and an IR laser at 5.9 mm with matrices of DHB and urea. Very interestingly, they found that the reductive hydrogenation was minimal in the IR MALDI process, suggesting few hydrogen radicals in the plume, in contrast to the UV MALDI process. Our objective is to try to simplify this problem by minimizing (or avoiding completely) the reduction in the UV MALDI process by selecting a suitable matrix. Recently, the application of graphene in MALDI-MS for analysis of small molecules and proteins has been reported. Dong et al. demonstrated that graphene was a useful matrix for small molecules such as amino acids and nucleosides. Zhang et al. found that some environmental contaminants, such as aromatic hydrocarbons, could be analyzed readily by MALDI-MS using a graphene matrix. Lu et al. found that better sensitivity and reproducibility were achieved in negative ion mode compared to positive ion mode when

Use of graphene as a matrix to minimize reduction in the process of matrix-assisted laser desorption/ionization.

With practical interest in the future applications of next-generation electronic devices, it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements. Herein, we design highly stretchable shape memory self-soldering conductive (SMSC) tape with reversible adhesion switched by temperature, which is composed of silver particles encapsulated by shape memory polymer. SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%. It also exhibits an initial conductivity of 2772 S cm−1 and a maximum tensile strain of ~ 100%. The maximum conductivity could be increased to 5446 S cm−1 by decreasing the strain to 17%. Meanwhile, SMSC tape can easily realize a heating induced reversible strong-to-weak adhesion transition for self-soldering circuit. The combination of stable conductivity, excellent shape memory performance, and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously. This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.

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Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature.

We present a new process to get in-situ-growth carbon nanotubes (CNTs) array device with good FE properties by CO(2)-assisted thermal chemical vapor deposition (CVD). Field Emission measurement shows that introducing CO(2) into CNTs growth system leads to a significant enhancement in the emission properties, both the turn-on field and threshold field decrease. Raman, SEM and TEM investigation results showed that in this CO(2)-assisted thermal CVD, CO(2) can remove amorphous carbon during CNTs growth process, and at the same time, it also creates more defects on the CNTs wall. Both can enhance FE properties of the CNTs at suitable CO(2) concentrations.

Yi Huang

Papers

Reply to 'Do thermal effects cause the propulsion of bulk graphene material?'

Mono-layer graphite oxide and water-soluble high molecule reinforced compound material

Use of graphene as a matrix to minimize reduction in the process of matrix-assisted laser desorption/ionization.

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature.

Enhancement of field emission of CNTs array by CO2-assisted chemical vapor deposition.