Pixel-Bit

Resumen tomado de la publicaciónSe presenta un modelo pedagógico con utilización de las TIC para la enseñanza de la Física Moderna en el Instituto Federal. El modelo está adaptado a las teorías del aprendizaje significativo de Ausubel y modelos mentales, analizados e implementados para transformar el aprendizaje de la Física Moderna. Esta propuesta busca facilitar el aprendizaje a través de la construcción de mapas conceptuales para mostrar la formación de modelos mentales. Se presentran los resultados que muestran un resultado positivo referido al aprendizaje de los alumnos de tercer curso de una escuela secundaria.ES

Real-Time 3D Single Particle Tracking: Towards Active Feedback Single Molecule Spectroscopy in Live Cells

Single molecule fluorescence spectroscopy has been largely implemented using methods which require tethering of molecules to a substrate in order to make high temporal resolution measurements. However, the act of tethering a molecule requires that the molecule be removed from its environment. This is especially perturbative when measuring biomolecules such as enzymes, which may rely on the non-equilibrium and crowded cellular environment for normal function. A method which may be able to un-tether single molecule fluorescence spectroscopy is real-time 3D single particle tracking (RT-3D-SPT). RT-3D-SPT uses active feedback to effectively lock-on to freely diffusing particles so they can be measured continuously with up to photon-limited temporal resolution over large axial ranges. This review gives an overview of the various active feedback 3D single particle tracking methods, highlighting specialized detection and excitation schemes which enable high-speed real-time tracking. Furthermore, the combination of these active feedback methods with simultaneous live-cell imaging is discussed. Finally, the successes in real-time 3D single molecule tracking (RT-3D-SMT) thus far and the roadmap going forward for this promising family of techniques are discussed

Real-time 3D single molecule tracking

Single molecule observation has been limited to tethered molecules to ensure that the target remains in the field of view (FOV). Here, the authors develop a real-time tracking method that locks onto rapidly diffusing targets and tracks them in a 3D volume, enabling single molecules to remain in the FOV for minutes at a time

Visualization 2: Robust real-time 3D single-particle tracking using a dynamically moving laser spot

Real-time movie of a gQD@SiO2 particle being tracked by 3D-DyPLoT. The 3D plot is the movement of the piezoelectric stage to hold the diffusing gQD@SiO2 in the objective focal volume. The inset is the sCMOS readout (3x3 Gaussian filter, false-color). Originally published in Optics Letters on 15 June 2017 (ol-42-12-2390

Visualization 3: Robust real-time 3D single-particle tracking using a dynamically moving laser spot

Real-time movie of a VSV-G-YFP virion being tracked by 3D-DyPLoT. The 3D plot is the movement of the piezoelectric stage to hold the diffusing virion in the objective focal volume. The inset is the sCMOS readout (3x3 Gaussian filter, false-color). Originally published in Optics Letters on 15 June 2017 (ol-42-12-2390

P and Mo Dual Doped Ru Ultrasmall Nanoclusters Embedded in P-Doped Porous Carbon toward Efficient Hydrogen Evolution Reaction

Rational design of efficient hydrogen evolution reaction (HER) electrocatalysts for mass production of hydrogen via electrochemical water splitting is a challenging but pressing task. Herein, an in situ dual doping engineering from phosphomolybdic acid encapsulated within the bimetallic metal-organic-frameworks strategy to synthesize P,Mo dual doped Ru ultrasmall nanoparticles embedded in P-doped porous carbon (P,Mo-Ru@PC) for efficient HER is proposed. As a result, P,Mo-Ru@PC achieves a low overpotential of 21 at 10 mA cm(-2), low Tafel slopes of 21.7 mV dec(-1), and a mass activity about 22 times greater than that of commercial 20 wt% Pt/C in alkaline media. First principle calculations demonstrate that introducing Mo and P atoms into Ru lattices triggers the in situ electron donation from Ru to Mo and P and consequently reduces the energy barrier for the HER

Boosting Hydrogen Evolution Reaction by Phase Engineering and Phosphorus Doping on Ru/P-TiO2

Synergistic optimization of the elementary steps of water dissociation and hydrogen desorption for the hydrogen evolution reaction (HER) in alkaline media is a challenge. Herein, the Ru cluster anchored on a trace P-doped defective TiO2 substrate (Ru/P-TiO2) was synthesized as an electrocatalyst for the HER; it exhibited a commercial Pt/C-like geometric activity and an excellent mass activity of 9984.3 mA mg(Ru)(-1) at -0.05 V vs. RHE, which is 34.3 and 18.7 times higher than that of Pt/C and Ru/TiO2, respectively. Experimental and theoretical studies indicated that using a rutile-TiO2-crystal-phase substrate enhanced the HER activity more than the anatase phase. Rich surface oxygen vacancies on rutile-TiO2 facilitated the adsorption and dissociation of water, while the partial substitution of Ti4+ with P5+ enhanced H-2 generation by facilitating hydrogen spillover from the Ru site to the surface P site, synergistically enhancing the HER activity

Electron‐deficient ZnO induced by heterointerface engineering as the dominant active component to boost CO2‐to‐formate conversion

Abstract Electrocatalytic CO2‐to‐formate conversion is considered an economically viable process. In general, Zn‐based nanomaterials are well‐known to be highly efficient electrocatalysts for the conversion of CO2 to CO, but seldom do they exhibit excellent selectivity toward formate. In this article, we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency (FE) of 86% at −0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO2 to formate than pristine ZnO and ZnSnO3. In particular, the FEs of the C1 products (CO + HCOO−) exceed 98% over the potential window. The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d‐band center, which results in moderate Zn–O hybridization of HCOO* and weakened Zn–C hybridization of competing COOH*, thus greatly boosting the HCOOH generation. Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO2 reduction

Single-Atom Sn on Tensile-Strained ZnO Nanosheets for Highly Efficient Conversion of CO2 into Formate

In general, commercial ZnO owns the poor selectivity and activity toward electroreduction CO2 to formate. In contrast, the numbers of Sn-based nanomaterials are reported as excellent electrocatalysts for formate production, however, the metallic Sn is more expensive than Zn. In this study, it is demonstrated that an atomically dispersed Sn on a tensile-strained ZnO nanosheet (Sn SA/ZnO) shows dramatically improved activity and selectivity for formate production over a wide potential window compared with that of commercial ZnO. Especially, Sn SA/ZnO exhibits 205-fold mass activity enhancement than the commercial Sn at -1.7 V versus reversible hydrogen electrode normalized with element Sn. The experimental measurements combined with theoretical calculations revealed that Sn SA/ZnO can effectively capture and activate CO2 by its exposed double-active sites (Sn and O), while the tensile strain on its surface boosts the catalytic selectivity by strengthening the adsorption of the *HCOO intermediate for the electrochemical reduction of CO2 to formate

Author Correction: Naturally-occurring cholesterol analogues in lipid nanoparticles induce polymorphic shape and enhance intracellular delivery of mRNA

An amendment to this paper has been published and can be accessed via a link at the top of the paper