Exclusion principle and the Landauer-Büttiker formalism

Hopping or Tunneling? Tailoring the Electron Transport Mechanisms through Hydrogen Bonding Geometry in the Boron-Doped Diamond Molecular Junctions

Mechanisms of charge transport in molecular junctions involving hydrogen bonds are complex and remain mostly unclear. This study is focused on the elucidation of the electron transfer in a molecular device consisting of two boron-doped diamond interfaces bound with an aromatic linker and a hydrogen bonding surrogating molecule. The projected local density of states (PLODS) analysis coupled with transmission spectra and current-voltage (I-V) simulations show that hydrogen bonding through electron-donating hydroxyl groups in the aromatic linker facilitates electron transfer, while the electron-withdrawing carboxyl group inhibits electron transfer across the junction. Moreover, slight variations in the geometry of hydrogen bonding lead to significant changes in the alignment of the energy levels and positions of the transmission modes. As a result, we observe the switching of the electron transport mechanism from tunneling to hopping accompanied by a change in the shape of the I-V curves and current magnitudes. These results give important information on the tailoring of the electronic properties of molecular junctions.

What Can We Learn from the Time Evolution of COVID-19 Epidemic in Slovenia?

A recent work indicates that temporarily splitting larger populations into smaller groups can efficiently mitigate the spread of SARS‐CoV‐2 virus. The fact that, soon afterward, the two million people Slovenia was the first European country proclaiming the end of COVID‐19 epidemic within national borders may be relevant from this perspective. Motivated by this evolution, in this paper the time dynamics of coronavirus cases in Slovenia is investigated with emphasis on how efficient various containment measures act to diminish the number of COVID‐19 infections. Noteworthily, the present analysis does not rely on any speculative theoretical assumption; it is solely based on raw epidemiological data. Out of the results presented here, the most important one is perhaps the finding that, while imposing drastic curfews and travel restrictions reduce the infection rate κ by a factor of four with respect to the unrestricted state, they only improve the κ‐value by ≈15% as compared to the much bearable state of social and economic life wherein wearing face masks and social distancing rules are enforced/followed. Significantly for behavioral and social science, our analysis may reveal an interesting self‐protection instinct of the population, which became manifest even before the official lockdown enforcement.

2D Sb2C3 monolayer: A promising material for the recyclable gas sensor for environmentally toxic nitrogen-containing gases (NCGs)

Based on density functional theory investigation, we exposed the potential application of hexagonal Sb₂C₃ nanosheet as highly sensitive material for nitrogen-containing gases (NCGs) NH₃, NO₂ and NO molecules. Our rigorous simulations show that NH₃, NO₂ and NO molecules shows physisorption on the Sb₂C₃ nanosheet via vdW DFT-D3 interactions. The calculations were carried out by considering that the monolayer Sb₂C₃ as the sensor material modulated with its electrical conductivity when its surface adsorbs the gas molecules for their various orientations and positions. It is also found that the magnetic properties are induced in non-magnetic Sb₂C₃ nanosheet by adsorption of NO molecule. The interaction of the Sb₂C₃ nanosheet with the gas molecules is further analysed by the charge density difference (CDD), electrostatic potential (ESP) and Bader charge analysis. Our analysis indicates a strong possibility for the detection of NO₂ and NO gas molecules by the Sb₂C₃ based sensor, due to the associated significant changes in the conductivity and reasonable adsorption energy. Also, in the visible region at T = 300 K, very low recovery times have been found as 431 μs, 785.01 s and 53.8 μs for NH₃, NO₂ and NO, respectively, which strongly suggest the Sb₂C₃ nanosheets as a better reversible multi-time gas sensor material towards the NCGs adsorption. We also explored the humidity effect on the NCGs based 2D Sb₂C₃ sensor material. The current-voltage (I-V) characteristics also confirmed the suitability of 2D Sb₂C₃ in real-time applications. Overall, present work reveals that the 2D Sb₂C₃ nanosheets as a promising material for semiconductor-based nano sensors for environmentally hazard pollutants like NCG molecules.

Suppression of Groups Intermingling as an Appealing Option for Flattening and Delaying the Epidemiological Curve While Allowing Economic and Social Life at a Bearable Level during the COVID-19 Pandemic

The COVID‐19 pandemic in a population modelled as a network wherein infection can propagate both via intra‐ and inter‐group interactions is simulated. The results emphasize the importance of diminishing the inter‐group infections in the effort of substantial flattening/delaying of the epi(demiologic) curve with concomitant mitigation of disastrous economy and social consequences. To exemplify, splitting a population into m (say, 5 or 10) noninteracting groups while keeping intra‐group interaction unchanged yields a stretched epidemiological curve having the maximum number of daily infections reduced and postponed in time by the same factor m (5 or 10). More generally, the study suggests a practical approach to fight against SARS‐ CoV‐ 2 virus spread based on population splitting into groups and minimizing intermingling between them. This strategy can be pursued by large‐scale infrastructure reorganization of activity at different levels in big logistic units (e.g., large productive networks, factories, enterprises, warehouses, schools, (seasonal) harvest work). Importantly, unlike total lockdown, the proposed approach prevents economic ruin and keeps social life at a more bearable level than distancing everyone from anyone. The declaration for the first time in Europe that COVID‐19 epidemic ended in the two‐million population Slovenia may be taken as support for the strategy proposed here.

Specific Features of Structure, Electrical Conductivity and Interlayer Adhesion of the Natural Polymer Matrix from the Layers of Branched Carbon Nanotube Networks Filled with Albumin, Collagen and Chitosan

This paper considers the problem of creating a conductive matrix with a framework made of carbon nanotubes (CNTs) for cell and tissue engineering. In silico investigation of the electrical conductivity of the framework formed by T-junctions of single-walled carbon nanotubes (SWNTs) (12, 12) with a diameter of 1.5 nm has been carried out. A numerical evaluation of the contact resistance and electrical conductivity of seamless and suture T-junctions of SWCNTs is given. The effect of the type of structural defects in the contact area of the tubes on the contact resistance of the T-junction of SWCNTs was revealed. A coarse-grained model of a branched SWCNT network with different structure densities is constructed and its electrical conductivity is calculated. A new layered bioconstruction is proposed, the layers of which are formed by natural polymer matrixes: CNT-collagen, CNT-albumin and CNT-chitosan. The energy stability of the layered natural polymer matrix has been analyzed, and the adhesion of various layers to each other has been calculated. Based on the obtained results, a new approach has been developed in the formation of 3D electrically conductive bioengineering structures for the restoration of cell activity.

Graphene thermal flux transistor

Insufficient flexibility of existing approaches to controlling the thermal transport in atomic monolayers limits their capability for use in many applications. Here, we examine the means of electrode doping to control the thermal flux Q due to phonons propagating along the atomic monolayer. We found that the frequency of the electron-restricted phonon scattering strongly depends on the concentration n_C. of the electric charge carriers, established by the electric potentials applied to local gates. As a result of the electrode doping, n_C is increased, causing a sharp rise in both the electrical conductivity and Seebeck coefficient, while the thermal conductivity tumbles. Therefore, the effect of the thermal transistor improves the figure of merit of nanoelectronic circuits.