Sc2CX (X=N2, ON, O2) MXenes as a promising anode material: A first-principles study

MXenes' tunable properties make them excellent candidates for many applications in future nanoelectronics. In this work, we explore the suitability of Sc$_2$CX (X=N$_2$, ON, O$_2$) MXenes to act as the active anode materials in Na-ion based batteries (NIBs) by means of \textsl{ab initio} simulations. After analyzing the structural and elastic properties of all the possible models to evaluate the energetically favorable N and O functionalization sites, our calculations show that both Sc$_2$CON and Sc$_2$CN$_2$ present a clear metallic character, making them potential candidates as anode materials. The investigation of the most relevant features for anode performance, such as the adsorption and diffusion of Na atoms, the intrinsic capacity, the open circuit voltage, and the storage capacity show that both systems are serious alternatives to the most common 2D materials currently employed in alkali metal batteries. In particular, Sc$_2$CN$_2$ presents a better diffusion behavior thanks to the absence of Na clustering on its surface, with optimal diffusion barriers comparable to other 2D materials such as MoN$_2$, while the values of diffusion barriers for Sc$_2$CON are at least three times smaller than those found for other anode candidates. Similarly, while the capacity of Sc$_2$CON is close to the one reported for 2D Sc$_2$C, Sc$_2$CN$_2$ possesses a power density more than twice higher than the ones of 2D materials such as Sc$_2$C, graphite, and MoS$_2$. Our results thus confirm the urge for further experimental exploration of the MXene Sc$_2$CX (X=N$_2$, ON, O$_2$) family as anode material in NIBs

Exploring a novel class of Janus MXenes by first principles calculations: structural, electronic and magnetic properties of Sc2CXT, X = O, F, OH; T = C, S, N

The already intriguing electronic and optical properties of the MXene Sc2C family can be further tuned through a wide range of possible functionalizations. Here, by means of density functional theory, we show that the 36 possible elements of the Janus MXT (M: Sc2C, X: O, F, OH, T: C, N, S) family, built by considering the four possible structural models (i) FCC, (ii) HCP, (iii) FCC + HCP, and (iv) HCP + FCC, are all potentially stable. The analysis of their mechanical properties shows the excellent mechanical flexibility of functionalized MXenes (f-MXenes) under large strain, making them more suitable for applications where stress could be an issue. Interestingly, while Sc2C presents a metallic character, Sc2COS, Sc2CFN and Sc2COHN are found to be semiconductors with bandgaps of 2.5 eV (indirect), 1.67 eV (indirect) and 1.1 eV (direct), respectively, which presents promising applications for nano- and optoelectronics. Moreover, Sc2CFC presents a ferromagnetic ground state with the 2 × 2 × 1 supercell magnetic moment of 3.99 μB, while the ground state of Sc2COHC might be antiferromagnetic with a magnetic moment of 3.98 μB, depending on the environment. Remarkably, the band structures of Sc2CFC and Sc2COHC present a half-metallic character with an HSE06 fundamental band gap of 0.60 eV and 0.48 eV, respectively. Our results confirm the extraordinary potential of the Janus MXT (M: Sc2C, X: O, F, OH, T: C, N, S) family for novel applications in 2D nano-,opto- and spintronics

La prueba pericial en el nuevo proceso penal

67 p.La realización de esta memoria tiene como objetivo principal, el análisis de la prueba pericial a la luz del nuevo sistema procesal penal instaurado en Chile y, que entró en vigencia a partir del año 2000 en algunas regiones de nuestro país. La idea es hacer notar las falencias, desventajas, vacíos y complicaciones en la aplicación de la prueba pericial, a raíz de la implementación del nuevo proceso. Para realizar el estudio y análisis pertinente se ha utilizado el método Jurídico- Dogmático, a través del cual hemos podido observar y corroborar que si bien es cierto, se le ha otorgado un mayor dinamismo como medio probatorio, y como consecuencia de esto, una mayor fuerza y relevancia jurídica, también es cierto que en pro de la transparencia del sistema, se ha consagrado formalismos que en la práctica otorgan a dicha prueba, un rasgo de ineficacia e inoperancia

Mitochondrial dysfunction generates aggregates that resist lysosomal degradation in human breast cancer cells

Disrupting functional protein homeostasis is an established therapeutic strategy for certain tumors. Ongoing studies are evaluating autophagy inhibition for overcoming chemotherapeutic resistance to such therapies by neutralizing lysosomal pH. New and sensitive methods to monitor autophagy in patients are needed to improve trial design and interpretation. We report that mitochondrial-damaged breast cancer cells and rat breast tumors accumulate p53-positive protein aggregates that resist lysosomal degradation. These aggregates were localized to enzymatically-active autolysosomes that were degrading autophagosomes and the autophagic receptor proteins TAX1BP1 and NDP52. NDP52 was identified to associate with aggregated proteins and knocking down NDP52 led to the accumulation of protein aggregates. TAX1BP1 was identified to partly localize with aggregates, and knocking down TAX1BP1 enhanced aggregate formation, suppressed autophagy, impaired NDP52 autophagic degradation and induced cell death. We propose that quantifying aggregates and autophagic receptors are two potential methods to evaluate autophagy and lysosomal degradation, as confirmed using primary human tumor samples. Collectively, this report establishes protein aggregates and autophagy receptors, TAX1BP1 and NDP52, as potential endpoints for monitoring autophagy during drug development and clinical studies

Differential and age-dependent expression of hyperpolarization-activated, cyclic nucleotide-gated cation channel isoforms 1-4 suggests evolving roles in the developing rat hippocampus.

Hyperpolarization-activated cation currents (I(h)) are found in several brain regions including thalamus and hippocampus. Important functions of these currents in promoting synchronized network activity and in determining neuronal membrane properties have been progressively recognized, but the molecular underpinnings of these currents are only emerging. I(h) currents are generated by hyperpolarization-activated, cyclic nucleotide-gated cation channels (HCNs). These channel proteins are encoded by at least four HCN genes, that govern the kinetic and functional properties of the resulting channels. Because of the potential impact of I(h)-mediated coordinated neuronal activity on the maturation of the functional hippocampal network, this study focused on determining the expression of the four members of the HCN gene family throughout postnatal hippocampal development at both the regional and single cell level.The results of these experiments demonstrated that HCNs 1, 2 and 4 are differentially expressed in interneuronal and principal cell populations of the rat hippocampal formation. Expression profiles of each HCN isoform evolve during postnatal development, and patterns observed during early postnatal ages differ significantly from those in mature hippocampus. The onset of HCN expression in interneurons of the hippocampus proper precedes that in the dentate gyrus, suggesting that HCN-mediated pacing activity may be generated in hippocampal interneurons prior to those in the hilus. Taken together, these findings indicate an age-dependent spatiotemporal evolution of specific HCN expression in distinct hippocampal cell populations, and suggest that these channels serve differing and evolving functions in the maturation of coordinated hippocampal activity

On average real sliding dynamics in linear systems

It is well known that in implementations of sliding mode controllers using hysteresis comparators, when the hysteresis band amplitude tends to zero the real dynamics tends to the ideal sliding dynamics. However, in real systems physical limitations do not allow to effectively lower this value at will, and a steady state error is likely to appear. In this paper we relate this error with a non zero average value of the switching function in each switching period: it is shown that, in linear systems, when the controller has a constant switching frequency and the switching function is periodic, the average value of the difference between real and ideal steady state dynamics is proportional to the average value of the switching function. Hence, when this average value is non zero an average steady state error appears, while a zero average value for the switching function entails no average steady state error. The proof is carried out using a regular form approach, and the result is exemplified in a buck converter. Simulation results show that when the switching function is periodic and shows a piecewise linear behavior within the hysteresis band, thus guaranteeing zero average value, the average state error disappears. In turn, when this piecewise linear character is lost and the switching function has non zero mean value, an average steady state error arises.Postprint (published version

Adsorbate and defect effects on electronic and transport properties of gold nanotubes

First-principles calculations have been performed to study the effects of adsorbates (CO molecules and O atoms) and defects on electronic structures and transport properties of Au nanotubes (Au(5, 3) and Au(5, 5)). For CO adsorption, various adsorption sites of CO on the Au tubes were considered. The vibrational frequency of the CO molecule was found to be very different for two nearly degenerate stable adsorption configurations of Au(5, 3), implying the possibility of distinguishing these two configurations via measuring the vibrational frequency of CO in experiments. After CO adsorption, the conductance of Au(5, 3) decreases by 0.9G0 and the conductance of Au(5, 5) decreases by approximately 0.5G0. For O-adsorbed Au tubes, O atoms strongly interact with Au tubes, leading to around 2G0 of drop in conductance for both Au tubes. These results may have implications for Au-tube-based chemical sensing. When a monovacancy defect is present, we found that, for both tubes, the conductance decreases by around 1G0. Another type of defect arising from the adhesion of one Au atom is also considered. For this case, it is found that, for the Au(5, 3) tube, the defect decreases the conductance by nearly 1G0, whereas for Au(5, 5), the decrease in conductance is only 0.3G0.Comment: 7 pages, 8 figure