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they were stored in room-air after the annealing procedure and prior to the SEM/EDX study. 100The Si content of the A layers in the novel structure is negligible, based on EDX results, and and what is present in similar systems, see S3 and S6. These calculations showed that 115

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Implications regarding requirements of performing a successive electrospinning and producing nanoporous polyetherimide (PEI) fibers are discussed through electrospinning PEI solutions of three nonvolatile solvents, that is, dimethylforamide (DMF), dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP), under atmospheres of constant temperature and varying levels of relative humidity (RH). The results demonstrate depending on nature of miscibility area in ternary phase diagram, a minimum RH is necessary to stabilize fiber formation. Furthermore, RH of operating environment affects diameter and both surface and interior morphologies of PEI electrospun fibers through involving the rate of phase demixing and viscoelasticity of solution. Considering fibers produced from NMP solutions because of delayed demixing, solvent drying precedes phase demixing or takes place in a comparable rate in high RH which leads to solid cross-section and texture-less surface with slight porosity. By choosing DMF or DMAc as electrospinning solvent, thicker fibers with rough surface and porous cross-section are expected.

Two-dimensional (2D) materials, especially their most prominent member, graphene, have greatly influenced many scientific areas. Moreover, they have become a base for investigating the relativistic properties of condensed matter within the emerging field of "Dirac physics." This has ignited an intense search for new materials where charge carriers behave as massless or massive Dirac fermions. Here, by the use of density functional theory and symmetry analysis, we theoretically show the existence of Dirac electrons in a series of 2D transition-metal carbides, known as MXenes. They possess eight conical crossings in the first Brillouin zone with giant spin-orbit splitting. Our findings indicate that the 2D band structure of MXenes is protected against external perturbations and preserved even in multilayer phases. These results, together with the broad possibilities to engineer the properties of these phases, make them a potential candidate for studying novel Dirac-physics-based applications.