Fundamentals, Progress and Perspectives on High-frequency Phononic Crystals

Phononic crystals (PnCs) are capable to manipulate the flow of elastic energy through their periodic structures and emerge as a promising field in the last two decades. Thanks to the advances in microfabrication technologies and developments of multifunctional materials, the engineering of periodic structures moves forward to the nanometer scale. Hence, the relevant frequencies of elastic waves are pushed toward the gigahertz regime where strong photon-phonon interactions trigger the applications of PnCs towards information and communication technologies. In this review, we present the experimental achievements on hypersonic PnCs involving microfabrication technologies to realize the desired structures and characterization of their band structures for unraveling phonon propagation modulation. Some application-orientated research directions are proposed in terms of advances in fabrication and characterization technologies and the development of electro-optomechanical systems.

Dipolar pathways in dipolar EPR spectroscopy

Dipolar electron paramagnetic resonance (EPR) experiments such as double electron--electron resonance (DEER) measure distributions of nanometer-scale distances between unpaired electrons, which provide valuable information for structural characterization of proteins and...

From Quark to Infinite Dimensionality

This article gives a overall picture of how the universe works from the likelihood that our universe is infinite dimensional at the nanometer scale of an indestructible quark. The article explains that we only can perceive for sure up to 4 dimensions of physical reality. However, the speculation in this article seems very clear that likely we are seeing activity in the 5th dimension in particle physics experimentation explaining the EPR paradox and other mysteries seen in particle physics. Finally, the article shows why the Mendeleev Chart has historically listed possible stable atoms without giving the exact number possible. The way protons and other hadrons are composed of six quarks and six antiquarks held together by gluons leads to the inevitable conclusion that only 108 stable atoms can exist. Being stable means the protons in an atom are composed of 3 quarks/antiquarks having charge 1. Recent discoveries in particle physics research demonstrates that there exists a particle named the pentaquark composed of five quarks. The article explains that pentaquarks have been identified in recent particle research. It is not known yet whether the pentaquark leads to a different proton that leads in turn to a pentaquark atom. New particle research will likely answer this question

High-frequency rectifying characteristics of metallic single-electron transistor with niobium nanodots

Metallic single-electron transistors (SETs) with niobium nanodots were fabricated, and their high-frequency rectifying characteristics were evaluated. By reducing the gap size of the electrodes and film deposition area to nanometer scale, improved SET characteristics with gate control, and better frequency response of the rectifying current with gentler decrease than 1/f at high frequency were achieved. The comparison between the characteristics of micrometer- and nanometer-size devices are made, and the reason for their differences are discussed with a help of simulation based on the experimentally extracted parameters.

Enhancing the Inhomogeneonus Photodynamics of Canonical Bacteriophytochrome

The ability of phytochromes to act as photoswitches in plants and microorganisms depends on interactions between a bilin-like chromophore and a protein. The interconversion occurs between the spectrally distinct red (Pr) and far-red (Pfr) conformers. This conformational change is triggered by the photoisomerization of the chromophore D-ring pyrrole. In this study, as a representative example of a phytochrome-bilin system, we take biliverdin IXα (BV) bound to bacteriophytochrome (BphP) from Deinococcus radiodurans. In the absence of light, we use an enhanced sampling molecular dynamics (MD) method to overcome the photoisomerization energy barrier. We find that the calculated free energy (FE) barriers between essential metastable states agree with spectroscopic results. We show that the enhanced dynamics of the BV chromophore in BphP triggers nanometer-scale conformational movements that propagate by two experimentally determined signal transduction pathways. Most importantly, we describe how the metastable states enable a thermal transition known as the dark reversion between Pfr and Pr, through a previously unknown intermediate state of Pfr. Here, for the first time, the heterogeneity of temperature-dependent Pfr states is presented at the atomistic level. This work paves a way toward understanding the complete mechanism of the photoisomerization of a bilin-like chromophore in phytochromes.