Plasmonic-enhanced photoluminescence in porous silicon with pore-embedded gold nanoparticles fabricated by direct reduction of chloroauric acid

The low efficiency of porous silicon (p-Si) luminescence hinders the development of silicon-based optoelectronic devices. The increase in p-Si emission using near-field enhancement, owing to the incorporation of gold nanoparticles (AuNPs) into the photonic structure, is probably the most viable alternative. However, the coupling of plasmon resonance to p-Si emission is challenging because of the difficulty in controlling the size and location of the AuNPs with respect to the emissive p-Si layer. In this study, AuNPs were synthesized by clean direct reduction of chloroauric acid inside a p-Si photonic structure. As a result, AuNPs could be synthesized all along the pores of the p-Si structure, allowing to obtain a six-fold enhancement of the p-Si photoluminescence, specifically for the emission band at 567 nm owing to the plasmon effect. Possible applications of this hybrid material include light-emitting devices and photoluminescence-based sensors

Landslide displacement forecasting using deep learning and monitoring data across selected sites

Accurate early warning systems for landslides are a reliable risk-reduction strategy that may significantly reduce fatalities and economic losses. Several machine learning methods have been examined for this purpose, underlying deep learning (DL) models’ remarkable prediction capabilities. The long short-term memory (LSTM) and gated recurrent unit (GRU) algorithms are the sole DL model studied in the extant comparisons. However, several other DL algorithms are suitable for time series forecasting tasks. In this paper, we assess, compare, and describe seven DL methods for forecasting future landslide displacement: multi-layer perception (MLP), LSTM, GRU, 1D convolutional neural network (1D CNN), 2xLSTM, bidirectional LSTM (bi-LSTM), and an architecture composed of 1D CNN and LSTM (Conv-LSTM). The investigation focuses on four landslides with different geographic locations, geological settings, time step dimensions, and measurement instruments. Two landslides are located in an artificial reservoir context, while the displacement of the other two is influenced just by rainfall. The results reveal that the MLP, GRU, and LSTM models can make reliable predictions in all four scenarios, while the Conv- LSTM model outperforms the others in the Baishuihe landslide, where the landslide is highly seasonal. No evident performance differences were found for landslides inside artificial reservoirs rather than outside. Furthermore, the research shows that MLP is better adapted to forecast the highest displacement peaks, while LSTM and GRU are better suited to model lower displacement peaks. We believe the findings of this research will serve as a precious aid when implementing a DL-based landslide early warning system (LEWS).SUPPORTO SCIENTIFICO PER L’OTTIMIZZAZIONE, IMPLEMENTAZIONE E GESTIONE DEL SISTEMA DI MONITORAGGIO CON AGGIORNAMENTO DELLE SOGLIE DI ALLERTAMENTO DEL FENOMENO FRANOSO DI SANT’ANDREA – PERAROLO DI CADORE (BL)” and the Spanish Grant “SARAI, PID2020-116540RB-C21,MCIN/AEI/10.13039/501100011033” and “RISKCOASTInSAR displacement data of the El Arrecife landslideGeohazard Exploitation Platform (GEP) of the European Space AgencyNoR Projects Sponsorship (Project ID: 63737

Bit-rock interaction in rotary drilling: numerical and experimental study

This investigation describes the dynamic model of a rotary drilling system equipped with a PDC bit. Torsional and axial dynamics are modeled separately with the bond graph technique and coupled is given by a bit-rock interaction model that considers cutting and friction components at the bit cutters. The cases for contact loss are analyzed and included as numerical functions to account for bit-bounce and stick-slip during drilling. Cosimulation of the drillstring and bit-rock models is proposed to simplify the numerical implementation. Verification confirmed that the model was captured with sufficient accuracy and yields predictable results for known inputs. A methodology for bit-rock parameter acquisition is suggested. Simulation of a real drilling setup was performed and validated against experimental tests. For the analyzed ranges, simulations were in agreement with experimental results. This shows that a close prediction of the drilling response of a PDC bit is possible with the considered model

Boletín MOMENTO ECONÓMICO, año 7, núm. 47, noviembre 2015 - febrero 2016

En este número de Momento Económico se analiza la situación actual del empleo remunerado en México, así como los rezagos y pendiente en esta materia. En seguida, se presenta un artículo que analiza la situación de la migración de mexicanos hacia Estados Unidos y las implicaciones para la economía mexicana del envío de remesas de nuestros conacionales al país, tema de fundamental importancia ante el contexto actual de creciente devaluación del peso

EXPERIENCIA DE IMPLANTACION DE VALVULAS AORTICAS VIA TRANSCATETER EN CENTRO MEDICO ISSEMYM TOLUCA DE JUNIO DE 2016 A JUNIO 2019.

La estenosis aórtica es la principal enfermedad valvular a nivel global. La degeneración valvular es la etiología más frecuente, seguido por enfermedades congénitas y reumáticas. La valvulopatía reumática ha reportado una disminución en su presentación. La calcificación valvular es considerada una enfermedad compleja, sistémica, con inflamación local, calcificación muy similar a la fisiopatología de la ateroesclerosis1,2,3. La*estenosis*aórtica* incrementa*de* forma* importante*con*la*edad,*la*hipertensión*arterial*sistémica*y*la*diabetes*mellitus,*la* calcificación* aórtica* se* ha* interpretado* como* una*manifestación* de* enfermedad* cardiovascular,* lo* que* la* ha* colocado* como* la* principal* causa* de*muerte* en* el* mundo3.** Aunque*se*tiene*un*conocimiento*amplio*de*la*fisiopatología*de*la*enfermedad,*aún* hay*puntos*que*están*en*discusiónh*un*ejemplo*de*esto*es:*en*qué*momento*se*debe* tratar* a* un* paciente* asintomático,* cuál* es* el* tratamiento* de* elección* (médico,* quirúrgico* o* tratamiento* intervencionista* con* la* colocación* de* endoprótesis* valvulares*TAVI),*entre*otros.*El*incremento*en*la*incidencia*de*la*enfermedad*nos* hace*reevaluar*el*manejo*de*este*grupo*de*pacientes*3.**UAEM, el autor

Generalizing segregation and chemical ordering in bimetallic nanoclusters through atomistic view points

"We predict general trends for surface segregation in binary metal clusters based on the difference between the atomic properties of the constituent elements. The energetically most favorable site for a guest atom on a pure metal cluster is determined considering the attractive and repulsive contributions of the cohesive energy of an atom in the cluster. It is predicted that for adjacent elements in a period of the periodic table, the bimetallic system would be more stable if the component with smallest valence electron density is placed on the surface. On the other hand, in bimetallic clusters built with elements of only one group, the trend to be in the volume (of the atomic component with smaller core density) will be higher for that cluster with atomic components most separated in the group. Such chemical ordering trends in the lowest energy configurations of Pt-Au, Pt-Pd, and Pt-Ni binary alloy clusters are verified for their 561 atom systems through a simulated annealing process. Some of our atomistic predictions are verified through quantum mechanical calculations.

Boletín MOMENTO ECONÓMICO, año 8, núm. 50, noviembre 2016-febrero 2017

En este número de Momento Económico se analiza el incremento del precio de las gasolinas considerando tres elementos que influyen en su determinación. Además, se hace un recuento de las principales ideas expresadas por los especialistas participantes en el Seminario de Pobreza, Desigualdad del Ingreso y Exclusión Social, realizado en el IIEc-UNAM. Finalmente, se presenta una reflexión sobre el proceso histórico estructural que incide en la persistencia de la pobreza

Klein paradox between transmitted and reflected Dirac waves on Bour surfaces

It is supposed the existence of a curved graphene sheet with the geometry of a Bour surface $B_{n}$, such as the catenoid (or helicoid), $B_{0}$, and the classical Enneper surface, $B_{2}$, among others. In particular, in this work, the propagation of the electronic degrees of freedom on these surfaces is studied based on the Dirac equation. As a consequence of the polar geometry of $B_{n}$, it is found that the geometry of the surface causes the Dirac fermions to move as if they would be subjected to an external potential coupled to a spin-orbit term. The geometry-induced potential is interpreted as a barrier potential, which is asymptotically zero. Furthermore, the behaviour of asymptotic Dirac states and scattering states are studied through the Lippmann-Schwinger formalism. It is found that for surfaces $B_{0}$ and $B_{1}$, the total transmission phenomenon is found for sufficiently large values of energy, while for surfaces $B_{n}$, with $n\geq 2$, it is shown that there is an energy point $E_{K}$ where Klein's paradox is realized, while for energy values $E\gg E_{K}$ it is found that the conductance of the hypothetical material is completely suppressed, $\mathcal{G}(E)\to 0$.Comment: 31 pages, 9 figure