Oxidation of 2D electrenes: structural transition and the formation of half-metallic channels protected by oxide layers

Based on first-principles calculations we performed a systematic study of the structural stability, and the electronic properties of oxidized $A_2B$, electrenes. Initially, we have considered one-side fully oxidized $A_2B$, single layer electrenes (O/$A_2B$), with $A$= Ba, Ca, Sr, Y, and $B$= As, N, P, C. We show that the hexagonal lattice of the pristine host is no longer the ground state structure in the oxidized systems. Our total energy results reveal an exothermic structural transition from hexagonal to tetragonal (h $\rightarrow$ t) geometry, resulting in layered tetragonal structures [($A$O$AB$)$^{\rm t}$]. Phonon spectra calculations show that the ($A$O$AB$)$^{\rm t}$, systems are dynamically stable for $A$= Ba, Ca, Sr, and $B$= N [($A$O$A$N)$^{\rm t}$]. In the sequence, we have examined the surface oxidation of bilayer systems [O/($A_2\text{N})_2$/O], with $A$= Ca, Sr, Ba, where we have also found an exothermic h $\rightarrow$ t transition to a dynamically stable layered tetragonal phase [$(A$O($A$N)$_2$$A$O)$^{\rm t}$]. Further electronic structure calculations of reveal the formation of half-metallic bands spreading through the $A$N layers. These findings indicate that ($A$O$A$N)$^{\rm t}$, and $(A$O($A$N)$_2$$A$O)$^{\rm t}$, are quite interesting platforms for application in spintronics; since the half-metallic channels along the $A$N and $(A\text{N})_2$ layers (core) are protected against the environment conditions by oxidized $A\text{O}$ sheets (cover shells).Comment: 8 pages, 6 figure

Self-assembly Of Nitpp On Cu(111): A Transition From Disordered 1d Wires To 2d Chiral Domains.

The growth and self-assembling properties of nickel-tetraphenyl porphyrins (NiTPP) on the Cu(111) surface are analysed via scanning tunnelling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). For low coverage, STM results show that NiTPP molecules diffuse on the terrace until they reach the step edge of the copper surface forming a 1D system with disordered orientation along the step edges. The nucleation process into a 2D superstructure was observed to occur via the interaction of molecules attached to the already nucleated 1D structure, reorienting molecules. For monolayer range coverage a 2D nearly squared self-assembled array with the emergence of chiral domains was observed. The XPS results of the Ni 2p(3/2) core levels exhibit a 2.6 eV chemical shift between the mono- and multilayer configuration of NiTPP. DFT calculations show that the observed chemical shifts of Ni 2p(3/2) occur due to the interaction of 3d orbitals of Ni with the Cu(111) substrate.1718344-1835

Machine learning of microscopic ingredients for graphene oxide/cellulose interaction

Understanding the role of microscopic attributes in nanocomposites allows for a controlled and, therefore, acceleration in experimental system designs. In this work, we extracted the relevant parameters controlling the graphene oxide binding strength to cellulose by combining first-principles calculations and machine learning algorithms. We were able to classify the systems among two classes with higher and lower binding energies, which are well defined based on the isolated graphene oxide features. By a theoretical X-ray photoelectron spectroscopy analysis, we show the extraction of these relevant features. Additionally, we demonstrate the possibilities of a refined control within a machine learning regression between the binding energy values and the system's characteristics. Our work presents a guiding map to the control graphene oxide/cellulose interaction

Fungal G-protein-coupled receptors::mediators of pathogenesis and targets for disease control

G-protein signalling pathways are involved in sensing the environment, enabling fungi to coordinate cell function, metabolism and development with their surroundings, thereby promoting their survival, propagation and virulence. G-protein-coupled receptors (GPCRs) are the largest class of cell surface receptors in fungi. Despite the apparent importance of GPCR signalling to fungal biology and virulence, relatively few GPCR–G-protein interactions, and even fewer receptor-binding ligands, have been identified. Approximately 40% of current pharmaceuticals target human GPCRs, due to their cell surface location and central role in cell signalling. Fungal GPCRs do not belong to any of the mammalian receptor classes, making them druggable targets for antifungal development. This Review Article evaluates developments in our understanding of fungal GPCR-mediated signalling, while substantiating the rationale for considering these receptors as potential antifungal targets. The need for insights into the structure–function relationship of receptor–ligand interactions is highlighted, which could facilitate the development of receptor-interfering compounds that could be used in disease control

Noncentrosymmetric two-dimensional Weyl semimetals in porous Si/Ge structures

In this work we predict a family of noncentrosymmetric two-dimensional (2D) Weyl semimetals composed by porous Ge and SiGe structures. These systems are energetically stable graphenylene-like structures with a buckling, spontaneously breaking the inversion symmetry. The nontrivial topological phase for these 2D systems occurs just below the Fermi level, resulting in nonvanishing Berry curvature around the Weyl nodes. The emerged Weyl semimetals are protected by $C_3$ symmetry, presenting one-dimensional edge Fermi-arcs connecting Weyl points with opposite chiralities. Our findings complete the family of Weyl in condensed-matter physics, by predicting the first noncentrosymmetric class of 2D Weyl semimetals

Bridging Borophene and Metal Surfaces: Structural, Electronic, and Electron Transport Properties

Currently, solid interfaces composed of two-dimensional materials (2D) in contact with metal surfaces (m-surf) have been the subject of intense research, where the borophene bilayer (BBL) has been considered a prominent material for the development of electronic devices based on 2D platforms. In this work, we present a theoretical study of the energetic, structural, and electronic properties of the BBL/m-surf interface, with m-surf = Ag, Au, and Al (111) surfaces, and the electronic transport properties of BBL channels connected to the BBL/m-surf top contacts. We find that the bottom-most BBL layer becomes metalized, due to the orbital hybridization with the metal surface states, resulting in BBL/m-surf ohmic contacts, meanwhile, the inner and top-most boron layers kept their semiconducting character. The net charge transfers reveal that BBL has become $n$-type ($p$-type) doped for m-surf = Ag, and Al (= Au). A thorough structural characterization of the BBL/m-surf interface, using a series of simulations of the X-ray photoelectron spectra, shows that the formation of BBL/m-surf interface is characterized by a redshift of the B-$1s$ spectra. Further electronic transport results revealed the emergence of a Schottky barrier between 0.1 and 0.2\,eV between the BBL/m-surf contact and the BBL channels. We believe that our findings are timely, bringing important contributions to the applicability of borophene bilayers for developing 2D electronic devices