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

Diarylethenes for Memories and Switches

Following Sharpless' visionary characterization of several idealized reactions as click reactions, the materials science and synthetic chemistry communities have pursued numerous routes toward the identification and implementation of these click reactions. Herein, we review the radical-mediated thiol-ene reaction as one such click reaction. This reaction has all the desirable features of a click reaction, being highly efficient, simple to execute with no side products and proceeding rapidly to high yield. Further, the thiol-ene reaction is most frequently photoinitiated, particularly for photopolymerizations resulting in highly uniform polymer networks, promoting unique capabilities related to spatial and temporal control of the click reaction. The reaction mechanism and its implementation in various synthetic methodologies, biofunctionalization, surface and polymer modification, and polymerization are all reviewed.

Thiol–Ene Click Chemistry

Organic–inorganic hybrid materials do not represent only a creative alternative to design new materials and compounds for academic research, but their improved or unusual features allow the development of innovative industrial applications. Nowadays, most of the hybrid materials that have already entered the market are synthesised and processed by using conventional soft chemistry based routes developed in the eighties. These processes are based on: a) the copolymerisation of functional organosilanes, macromonomers, and metal alkoxides, b) the encapsulation of organic components within sol–gel derived silica or metallic oxides, c) the organic functionalisation of nanofillers, nanoclays or other compounds with lamellar structures, etc. The chemical strategies (self-assembly, nanobuilding block approaches, hybrid MOF (Metal Organic Frameworks), integrative synthesis, coupled processes, bio-inspired strategies, etc.) offered nowadays by academic research allow, through an intelligent tuned coding, the development of a new vectorial chemistry, able to direct the assembling of a large variety of structurally well defined nano-objects into complex hybrid architectures hierarchically organised in terms of structure and functions. Looking to the future, there is no doubt that these new generations of hybrid materials, born from the very fruitful activities in this research field, will open a land of promising applications in many areas: optics, electronics, ionics, mechanics, energy, environment, biology, medicine for example as membranes and separation devices, functional smart coatings, fuel and solar cells, catalysts, sensors, etc.

Applications of hybrid organic–inorganic nanocomposites

As a growing applied science, nanotechnology has considerable global socioeconomic value, and the benefits afforded by nanoscale materials and processes are expected to have significant impacts on almost all industries and all areas of society. A diverse array of engineered nanoscale products and processes have emerged [e.g., carbon nanotubes, fullerene derivatives, and quantum dots (QDs)], with widespread applications in fields such as medicine, plastics, energy, electronics, and aerospace. With the nanotechnology economy estimated to be valued at $1 trillion by 2012, the prevalence of these materials in society will be increasing, as will the likelihood of exposures. Importantly, the vastness and novelty of the nanotechnology frontier leave many areas unexplored, or underexplored, such as the potential adverse human health effects resulting from exposure to novel nanomaterials. It is within this context that the need for understanding the potentially harmful side effects of these materials becomes clear. The reviewed literature suggests several key points: Not all QDs are alike; engineered QDs cannot be considered a uniform group of substances. QD absorption, distribution, metabolism, excretion, and toxicity depend on multiple factors derived from both inherent physicochemical properties and environmental conditions; QD size, charge, concentration, outer coating bioactivity (capping material and functional groups), and oxidative, photolytic, and mechanical stability have each been implicated as determining factors in QD toxicity. Although they offer potentially invaluable societal benefits such as drug targeting and in vivo biomedical imaging, QDs may also pose risks to human health and the environment under certain conditions.

A toxicologic review of quantum dots: toxicity depends on physicochemical and environmental factors.

Lanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking.

Functionalized fluorescent oxide nanoparticles: Artificial toxins for sodium channel targeting and imaging at the single-molecule level

We have developed new transparent photochromic hybrid organic−inorganic materials in which the photochromic group belongs to the polymer network. These materials involving chemically bonded dithienylethene derivatives were prepared by the sol−gel process in the form of thin films a few microns thick. The thickness and refractive index of the sol−gel films either at 633 or 785 nm were determined both in the colored and discolored state by using the attenuated total reflection (ATR) method. Functionalized sol−gel films showed a large refractive index change in a nonabsorbing spectral region:  Δn ≈ 4 × 10-2 at 785 nm. This important variation due to the high photochrome content allowed us to design optical components used in the field of wave guiding.

Large and Stable Refractive Index Change in Photochromic Hybrid Materials

The local optical field enhancement which can occur at the end of a nanometer-size metallic tip has given rise to both increasing interest and numerous theoretical works on near-field optical microscopy. In this article we report direct experimental observation of this effect and present an extensive study of the parameters involved. Our approach consists in making a “snapshot” of the spatial distribution of the optical intensity in the vicinity of the probe end using photosensitive azobenzene-containing films. This distribution is coded by optically induced surface topography which is characterized in situ by atomic force microscopy using the same probe. We perform an extensive analysis of the influence of several experimental parameters. The results are analyzed as a function of the illumination parameters (features of the incident laser beam, exposure time, illumination geometry) as well as the average tip-to-sample distance and tip geometry. The results obtained provide substantial information about t...

Apertureless near-field optical microscopy: A study of the local tip field enhancement using photosensitive azobenzene-containing films

The series of new bis(tetrathiafulva1ene) [bis(TTF)] compounds 10-12a,b have been synthetized with the TTF-like synthon 8a,b, previously used to prepare the pyrazine-fused bis("F) 7a,b. These compounds exhibit four reversible sequential one-electron oxidation steps, on the basis of cyclic voltammetry. For the cation radicals 7b.+,10 .+,and 12.+, generated electrochemically, rather intense and broad bands in the near-IR region, specific of class 11 mixed valence compounds, were found. Theoretical calculations at the semiempirical AM1 level as well as at the ab-initio level indicated that these cation radicals are charge-distributions localized as related to mixed valence species. These calculations also allowed the low-energy absorption bands to be assigned to intervalence transitions; these transitions imply the existence of multiple low-lying excited states that are non-adiabatically coupled to the ground-state of these open-shell species.

Khalid Lahlil

Papers

Functionalized fluorescent oxide nanoparticles: Artificial toxins for sodium channel targeting and imaging at the single-molecule level

Large and Stable Refractive Index Change in Photochromic Hybrid Materials

Apertureless near-field optical microscopy: A study of the local tip field enhancement using photosensitive azobenzene-containing films

Intervalence transitions in mixed-valence bis(tetrathiafulvalene) compounds

Hybrid Organic–Inorganic Light-Emitting Diodes