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

Anyone who ever took an electronics laboratory class will be familiar with the fundamental passive circuit elements: the resistor, the capacitor and the inductor. However, in 1971 Leon Chua reasoned from symmetry arguments that there should be a fourth fundamental element, which he called a memristor (short for memory resistor). Although he showed that such an element has many interesting and valuable circuit properties, until now no one has presented either a useful physical model or an example of a memristor. Here we show, using a simple analytical example, that memristance arises naturally in nanoscale systems in which solid-state electronic and ionic transport are coupled under an external bias voltage. These results serve as the foundation for understanding a wide range of hysteretic current-voltage behaviour observed in many nanoscale electronic devices that involve the motion of charged atomic or molecular species, in particular certain titanium dioxide cross-point switches.

/pdf/the-missing-memristor-found-55upit5xe7.pdf

The missing memristor found

Many metal–insulator–metal systems show electrically induced resistive switching effects and have therefore been proposed as the basis for future non-volatile memories. They combine the advantages of Flash and DRAM (dynamic random access memories) while avoiding their drawbacks, and they might be highly scalable. Here we propose a coarse-grained classification into primarily thermal, electrical or ion-migration-induced switching mechanisms. The ion-migration effects are coupled to redox processes which cause the change in resistance. They are subdivided into cation-migration cells, based on the electrochemical growth and dissolution of metallic filaments, and anion-migration cells, typically realized with transition metal oxides as the insulator, in which electronically conducting paths of sub-oxides are formed and removed by local redox processes. From this insight, we take a brief look into molecular switching systems. Finally, we discuss chip architecture and scaling issues.

http://chialvo.org/Curso/UBACurso/DIA7/Papers/Aono_NatMat_07_Ionic%20Switching%20Memory.pdf

Nanoionics-based resistive switching memories

Fluorescent carbon nanoparticles or carbon quantum dots (CQDs) are a new class of carbon nanomaterials that have emerged recently and have garnered much interest as potential competitors to conventional semiconductor quantum dots. In addition to their comparable optical properties, CQDs have the desired advantages of low toxicity, environmental friendliness low cost and simple synthetic routes. Moreover, surface passivation and functionalization of CQDs allow for the control of their physicochemical properties. Since their discovery, CQDs have found many applications in the fields of chemical sensing, biosensing, bioimaging, nanomedicine, photocatalysis and electrocatalysis. This article reviews the progress in the research and development of CQDs with an emphasis on their synthesis, functionalization and technical applications along with some discussion on challenges and perspectives in this exciting and promising field.

Carbon quantum dots and their applications

Self-Assembly of Discrete Cyclic Nanostructures Mediated by Transition Metals

The Regioselective Generation of Arynes from Polyhalogenobenzenes. An Improved Synthesis of syn‐ and anti‐1,4,5,8,9,12‐Hexahydro‐1,4:5,8:9, 12‐triepoxytriphenylene.

A New Route to Phenanthrene Derivatives.

This tutorial review illustrates how work on the reversible interconversion between the colorless and colored forms of photochromic compounds can be exploited to modulate electron and energy transfer processes. Indeed, a photochrome can be designed to accept electrons or energy from a complementary donor in one of its two states only. Alternatively, the photoinduced transformations associated with a photochromic switch can be engineered to control the relative orientation and distance of donor–acceptor pairs. If either the donor or the acceptor is fluorescent, the photoregulated transfer of energy or electrons results in the modulation of the emission intensity. Thus, these fascinating molecular and supramolecular systems can advance the basic understanding of electron and energy transfer processes, while leading to viable operating principles to control light with light.

Electron and Energy Transfer Modulation with Photochromic Switches

Electron Transfer Quenching for Biosensing with Quantum Dots

Photoactivated localization microscopy (PALM) relies on fluorescence photoactivation and single-molecule localization to overcome optical diffraction and reconstruct images of biological samples with spatial resolution at the nanoscale. The implementation of this subdiffraction imaging method, however, requires fluorescent probes with photochemical and photophysical properties specifically engineered to enable the localization of single photoactivated molecules with nanometer precision. The synthetic versatility and outstanding photophysical properties of the borondipyrromethene (BODIPY) chromophore are ideally suited to satisfy these stringent requirements. Specifically, synthetic manipulations of the BODIPY scaffold can be invoked to install photolabile functional groups and photoactivate fluorescence under photochemical control. Additionally, targeting ligands can be incorporated in the resulting photoactivatable fluorophores (PAFs) to label selected subcellular components in live cells. Indeed, photoactivatable BODIPYs have already allowed the sub-diffraction imaging of diverse cellular substructures in live cells using PALM and can evolve into invaluable analytical probes for bioimaging applications.

/pdf/photoactivatable-bodipys-for-live-cell-palm-u0vd1qg0.pdf

Françisco M. Raymo

Papers

The Regioselective Generation of Arynes from Polyhalogenobenzenes. An Improved Synthesis of syn‐ and anti‐1,4,5,8,9,12‐Hexahydro‐1,4:5,8:9, 12‐triepoxytriphenylene.

A New Route to Phenanthrene Derivatives.

Electron and Energy Transfer Modulation with Photochromic Switches

Electron Transfer Quenching for Biosensing with Quantum Dots

Photoactivatable BODIPYs for Live-Cell PALM