No abstract

We herein demonstrate that capacitance spectroscopy (CS) experimentally allows access to the energy associated with the quantum mechanical ground state of many-electron systems. Priorly, electrochemical capacitance, C[ρ], was previously understood from conceptual and computational density functional theory (DFT) calculations. Thus, we herein propose a quantum mechanical experiment-based variational method for electron charging processes based on an experimentally-designed functional of the ground state electron density. In this methodology, the electron state density, ρ, and an energy functional of the electron density, E[ρ], can be obtained from CS data. CS allows the derivative of the electrochemical potential with respect to the electron density, (δ[small mu, Greek, macron][ρ]/δρ), to be obtained as a unique functional of the energetically minimised system, i.e., β/C[ρ], where β is a constant (associated with the size of the system) and C[ρ] is an experimentally observable quantity. Thus the ground state energy (at a given fixed external potential) can be obtained simply as E[ρ], from the experimental measurement of C[ρ]. An experimental data-set was interpreted to demonstrate the potential of this quantum mechanical experiment-based variational principle.

Meningiomas are usually considered to be benign central nervous system tumors; however, they show heterogenous clinical, histolopathological and cytogenetic features associated with a variable outcome. In recent years important advances have been achieved in the identification of the genetic/molecular alterations of meningiomas and the signaling pathways involved. Thus, monosomy 22, which is often associated with mutations of the NF2 gene, has emerged as the most frequent alteration of meningiomas; in addition, several other genes (e.g. AKT1, KLF4, TRAF7, SMO) and chromosomes have been found to be recurrently altered often in association with more complex karyotypes and involvement of multiple signaling pathways. Here we review the current knowledge about the most relevant genes involved and the signaling pathways targeted by such alterations. In addition, we summarize those proposals that have been made so far for classification and prognostic stratification of meningiomas based on their genetic/genomic features.

The absolute chemical hardness η for a chemical system under a steady external potential υ containing N electrons and an energy E(N) was defined by Robert Parr and Ralph Pearson as η = (δ2 E/δN 2)υ. Chemical hardness is a widely accepted concept in chemistry that serves as a reactivity index for describing the stability of compounds and reaction mechanisms in the framework of hard and soft acid and base theory. In a previous study, we demonstrated that it is possible to formulate a total energy functional of electronic density that is directly correlated to the experimental data obtained from mesoscopic electrochemical systems. The present study extends the use of this experimentally designed functional to determine and analyze the chemical hardness of mesoscopic electrochemical systems directly from the experimental data. We demonstrate that it is possible to rapidly scan the physical properties and chemical reactivity indexes of mesoscopic electrochemical systems at different external potentials and a finite temperature using the grand canonical ensemble.