Synthesis of 3-Acyl and 3-Carboalkoxyfurans by the Ceric Ammonium Nitrate Promoted Addition of 1,3-Dicarbonyl Compounds to Vinylic Acetates

3-Acyl- and 3-carboalkoxyfurans can be prepared in 30–55% yield by the oxidative addition of 1,3-dicarbonyl compounds to vinylic acetates induced by eerie ammonium nitrate.     

Light‐Induced Porphyrin‐Based Spectroscopic Ruler for Nanometer Distance Measurements

We present a novel pulsed electron paramagnetic resonance (EPR) spectroscopic ruler to test the performance of a recently developed spin‐labeling method based on the photoexcited triplet state (S=1). Four‐pulse electron double resonance (PELDOR) experiments are carried out on a series of helical peptides, labeled at the N‐terminal end with the porphyrin moiety, which can be excited to the triplet state, and with the nitroxide at various sequence positions, spanning distances in the range 1.8–8 nm. The PELDOR traces provide accurate distance measurements for all the ruler series, showing deep envelope modulations at frequencies varying in a progressive way according to the increasing distance between the spin labels. The upper limit is evaluated and found to be around 8 nm. The PELDOR‐derived distances are in excellent agreement with theoretical predictions. We demonstrate that high sensitivity is acquired using the triplet state as a spin label by comparison with Cu(II)–porphyrin analogues. The new labeling approach has a high potential for measuring nanometer distances in more complex biological systems due to the properties of the porphyrin triplet state.     

Interpretation of Quantum Nonlocality by Conformal Quantum Geometrodynamics

The principles and methods of the Conformal Quantum Geometrodynamics (CQG) based on the Weyl’s differential geometry are presented. The theory applied to the case of the relativistic single quantum spin \(\frac{1}{2}\) leads a novel and unconventional derivation of Dirac’s equation. The further extension of the theory to the case of two spins \(\frac{1}{2}\) in EPR entangled state and to the related violation of Bell’s inequalities leads, by a non relativistic analysis, to an insightful resolution of the enigma implied by quantum nonlocality.     

A Quantum Computational Semantics for Epistemic Logical Operators. Part II: Semantics

By using the abstract structures investigated in the first Part of this article, we develop a semantics for an epistemic language, which expresses sentences like “Alice knows that Bob does not understand that π is irrational”. One is dealing with a holistic form of quantum computational semantics, where entanglement plays a fundamental role; thus, the meaning of a global expression determines the contextual meanings of its parts, but generally not the other way around. The epistemic situations represented in this semantics seem to reflect some characteristic limitations of the real processes of acquiring information. Since knowledge is not generally closed under logical consequence, the unpleasant phenomenon of logical omniscience is here avoided.     

Real-time manipulation of gold nanoparticles inside a scanning electron microscope

The forces needed to overcome static friction and move 150 nm diameter Au nanoparticles on an oxidized Si substrate were measured in Normal and Shear oscillation modes inside a scanning electron microscope (SEM) in real time. The experimental setup consisted of a quartz tuning fork (QTF) mounted onto a high-precision 3D nanomanipulator used with a glued silicon or tungsten tip as a force sensor. Static friction was found to range from tens of nN to several hundred nN. Large variations in static friction values were related to differences in particle shape. Kinetic friction tended to be close to the detection limit and in most cases did not exceed several nN. The influence of thermal treatment in reducing the static friction of nanoparticles was considered.     

Coupled-resonator optical waveguides: Q-factor and disorder influence

Coupled resonator optical waveguides (CROW) can significantly reduce light propagation pulse velocity due to pronounced dispersion properties. A number of interesting applications have been proposed to benefit from such slow-light propagation. Unfortunately, the inevitable presence of disorder, imperfections, and a finite Q value may heavily affect the otherwise attractive properties of CROWs. We show how finite a Q factor limits the maximum attainable group delay time; the group index is limited by Q, but equally important the feasible device length is itself also limited by damping resulting from a finite Q. Adding the additional effects of disorder to this picture, limitations become even more severe due to destructive interference phenomena, eventually in the form of Anderson localization. Simple analytical considerations demonstrate that the maximum attainable delay time in CROWs is limited by the intrinsic photon lifetime of a single resonator.