Black holes in economics

The economics is one of the most complex systems in nature. There is still no united view on all processes happen there. Here we would like to present a geometrical approach to economics, where we introduce a new concept of economic metric space. We show that there may exist black holes, the objects, which may play a crucial role in the economics dynamics. We argue that the existence of black holes in such system from one side may stimulate economics while from other side may originate financial crisis

Optical Transistor for Amplification of Radiation in a Broadband Terahertz Domain

We propose a new type of optical transistor for a broadband amplification of THz radiation. It is made of a graphene–superconductor hybrid, where electrons and Cooper pairs couple by Coulomb forces. The transistor operates via the propagation of surface plasmons in both layers, and the origin of amplification is the quantum capacitance of graphene. It leads to THz waves amplification, the negative power absorption, and as a result, the system yields positive gain, and the hybrid acts like an optical transistor, operating with the terahertz light. It can, in principle, amplify even a whole spectrum of chaotic signals (or noise), that is required for numerous biological applications

Comparison of Strategy 1 and Strategy 4 of the output power of renewable energy and the energy storage in 24 hours.

<p>Comparison of Strategy 1 and Strategy 4 of the output power of renewable energy and the energy storage in 24 hours.</p

Comparison of Strategy 2 and Strategy 3 of capacity value of the energy storage against X% of peak load.

<p>Comparison of Strategy 2 and Strategy 3 of capacity value of the energy storage against X% of peak load.</p

Active Sites of Pd-Doped Flat and Stepped Cu(111) Surfaces for H₂ Dissociation in Heterogeneous Catalytic Hydrogenation

It has been shown in recent experiments that the Cu(111) surface doped by a small amount of Pd atoms can exhibit excellent catalytic performance toward the dissociation of H₂ molecules. Here we performed systematic first-principles calculations to investigate the corresponding mechanism. Our results clearly demonstrate that a very small number of Pd atoms in the subsurface layer can effectively reduce the energy barrier of H₂ dissociation, making the ensembles composed of the surface and contiguous subsurface Pd atoms as the active sites. The catalytic activity can be further improved if the Pd atoms are doped in the stepped Cu surfaces. The impact of the subsurface Pd atoms comes from an enhanced surface–adsorbate interaction caused by adjusting the electronic structure of the substrate. The important role played by the subsurface atoms offers an efficient approach to finely tune the surface activity by a very limited number of atoms. Our findings should be very useful for understanding and improving the catalytic properties of alloy systems for the industrially important hydrogenation reactions

Variations of the capacity value of energy storage for different <i>E</i>_<i>max</i> of energy storage.

<p>Variations of the capacity value of energy storage for different <i>E</i>_<i>max</i> of energy storage.</p

Variations of the capacity value of energy storage against different maximum discharge power values of energy storage.

<p>Variations of the capacity value of energy storage against different maximum discharge power values of energy storage.</p

New Mechanism for Photocatalytic Reduction of CO₂ on the Anatase TiO₂(101) Surface: The Essential Role of Oxygen Vacancy

Photocatalytic reduction of CO₂ into organic molecules is a very complicated and important reaction. Two possible pathways, the fast-hydrogenation (FH) path and the fast-deoxygenation (FdO) path, have been proposed on the most popular photocatalyst TiO₂. We have carried out first-principles calculations to investigate both pathways on the perfect and defective anatase TiO₂(101) surfaces to provide comprehensive understanding of the reaction mechanism. For the FH path, it is found that oxygen vacancy on defective surface can greatly lower the barrier of the deoxygenation processes, which makes it a more active site than the surface Ti. For the FdO path, our calculation suggests that it can not proceed on the perfect surface, nor can it proceed on the defective surface due to their unfavorable energetics. Based on the fact that the FH path can proceed both at the surface Ti site and the oxygen vacancy site, we have proposed a simple mechanism that is compatible with various experiments. It can properly rationalize the selectivity of the reaction and greatly simplify the picture of the reaction. The important role played by oxygen vacancy in the new mechanism is highlighted and a strategy for design of more efficient photocatalysts is proposed accordingly

Variations of the capacity value of energy storage against different peak load.

<p>Variations of the capacity value of energy storage against different peak load.</p

Isomer-Dependent Franck–Condon Blockade in Weakly Coupled Bipyridine Molecular Junctions

Franck–Condon blockade is an attractive functionality of molecular junctions, but its tunability is still a challenge that has not been fully addressed. We show here from first-principles calculations that the electron–vibration coupling strength of a weekly coupled bipyridine molecular junction can be largely tuned from weak to strong coupling regime through isomerization. Electron transport properties of four bipyridine isomers, namely 2,6′-bipyridine, 2,4′-bipyridine, 2,2′-bipyridine, and 4,4′-bipyridine, have been exclusively examined. A very strong Franck–Condon blockade is found to be associated with 2,2′-bipyridine and 4,4′-bipyridine molecules and should be observable experimentally. A gate-controlled conductance switch is proposed for a molecular junction with a 4,4′-bipyridine molecule. Our calculations have clearly demonstrated that bipyridine isomers are excellent candidates for the experimental study of vibration-mediated transport properties in a single molecule