Theoretical Study on the 3D Aromaticity in Cationic X44+ (X=O, S, Se, and Te) Clusters

AbstractThe stable structures and 3D aromatic characters for four cationic X44+(X=O, S, Se, and Te) clusters are investigated at the DFT and post HF level of theory with the extended 6-311+G* basis set used for O, S, Se atoms and correlation consistent, effective-core potential (ECP) basis set ECP46MWB_AVTZ for the heavier Te atom. Two optimized structures of tetrahedron (Td) and rhombus (D2h) for four X44+ species have been obtained. The calculated results show that the tetrahedral (Td) structures are stable and correspond to energy minima, whereas the rhombic (D2h) ones are unstable and have one or more saddle points on the potential energy surfaces. The calculated NICS values show that four tetrahedral X44+ isomers have higher degree of 3D aromaticities. Whereas four rhombic X44+ isomers can be regarded to possess 3D antiaromaticities. The molecular orbital analyses reveal that the tetrahedral X44+ cations possess two-fold (σ and π) 3D aromaticity, conforming to the 2(N+1)2 electron counting rule for 3D aromaticit

The Friedmann equation in modified entropy-area relation from entropy force

According to the formal holographic principle, a modification to the assumption of holographic principle in Verlinder's investigation of entropy force is obtained. A more precise relation between entropy and area in the holographic system is proposed. With the entropy corrections to the area-relation, we derivate Newton's laws and Einstein equation with a static spherically symmetric holographic screen. Furthermore we derived the correction terms to the modified Friedmann equation of the FRW universe starting from the holographic principle and the Debye model.Comment: Mod. Phys. Lett. A26, 489-500 (2011

Generation of spatially-separated spin entanglement in a triple quantum dot system

We propose a novel method for the creation of spatially-separated spin entanglement by means of adiabatic passage of an external gate voltage in a triple quantum dot system.Comment: 10 pages, 6 figure

Hydroxymethyl furfural in chinese herbal medicines: Its formation, presence, metabolism, bioactivities and implications

Background: Chinese herbal medicines (CHMs) must be processed before being prescribed to patients. During the processing, some CHMs became brown and as such 5-hydroxymethyl furfural (HMF) generated. Increasing attention is being paid to the safety and effectiveness of HMF.Methods: This paper summarized previous and recent reports on HMF formation, its presence in CHMs, its metabolism and bioactivities, together with its implications for CHMs.Results: HMF had been detected in 41 CHMs, and increased by about 12~1200 times after heat processing in some CHMs. Current data showed that HMF has limited genotoxicity but various bioactivities, such as anti-oxidative, anti-apoptotic, anti-inflammatory, anti-hypoxic, anti-microbial, and inhibiting sickling of red blood cells.Conclusion: Accumulation of HMF during heat processing of CHMs indicates that Maillard reaction and caramelization occurred. The other products of the two browning reactions deserve more attention in the following investigations on heat processed CHM.Keywords: hydroxymethyl furfural, Chinese herbal medicine, Maillard reaction, caramelization

Electric field tunable multi-state tunnel magnetoresistances in 2D van der Waals magnetic heterojunctions

Magnetic tunnel junction (MTJ) based on van der Waals (vdW) magnetic layers has been found to present excellent tunneling magnetoresistance (TMR) property, which has great potential applications in field sensing, non-volatile magnetic random access memories, and spin logics. Although MTJs composed of multilayer vdW magnetic homojunctions have been extensively investigated, the ones composed of vdW magnetic heterojunction is still to be explored. Here we use first-principles approaches to reveal that the magnetic heterojunction MTJs have much more distinguishable TMR values than the homojunction ones. In the MTJ composed of bilayer CrI3/bilayer Cr2Ge2Te6 heterojunction, we find there are eight stable magnetic states, leading to seven distinguishable electronic resistances. As a result, six sizable TMRs larger than 600% can be obtained (the maximum TMR is up to 120,000%). The number of distinguishable memories is more than two times larger than that of a four-layered homojunction MTJ. The underlying relationships among magnetic state, spin-polarized band structures, and transmission spectrums are further revealed to explain the multiple TMR values. We also find that the magnetic states and thus TMRs can be efficiently modulated by an external electric field. This study opens an avenue to the design of high-performance MTJ devices based on vdW heterojunctions.Comment: 6 figure

Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells

We study the hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells. The corresponding polariton states are given. The analytical solution and the numerical result of the stationary spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic