Search results for "complexity"
showing 10 items of 1094 documents
Three-ring filters increase the effective NA up to 1.46 in optical sectioning fluorescence microscopy
2003
Single-photon fluorescence confocal microscopy techniques can be combined with the use of specific binary filters in order to increase their optical sectioning capability. We present a novel class of axially super-resolving binary pupil filters specially designed to reach this aim. These filters let us to obtain a relevant compression of the z-response together with the reduction of the photo-bleaching effect typically inherent to apodization techniques. The fact of joining both the three-ring filters we propose in the illumination path, and the confocal detection gives rise to an important effective increase of lenses of effective numerical aperture.
An Investigation into the Stability of Graphitic C 3 N 4 as a Photocatalyst for CO 2 Reduction
2018
The increasing CO 2 concentration in the atmosphere exerts a significant influence on global warming and climate change. The capture and utilization of CO 2 by conversion to useful products is an area of active research. In this work, the photodriven reduction of CO 2 was investigated using graphitic carbon nitride (g-C 3 N 4 ) as a potential photocatalyst. The photocatalytic reduction of CO 2 was investigated with g-C 3 N 4 powder immobilized on a glass support in a batch gas-phase photoreactor. The experiments were carried out under UV-vis irradiation at 70 °C and an initial pressure of 2.5 bar. The only gas-phase product detected during the irradiation of the g-C 3 N 4 in the presence of…
Field-induced slow relaxation of magnetisation in an anionic heterotetranuclear [ZnIIReIV3] system
2019
The compound (NBu4)4[ZnII{ReIVCl4(μ-ox)}3] (1) [NBu4+ = tetra-n-butylammonium cation and ox2− = oxalate dianion] is the first example of an oxalato-bridged ZnII system coordinated to a 5d metal ion that exhibits slow relaxation of magnetisation.
Exploiting Reaction-Diffusion Conditions to Trigger Pathway Complexity in the Growth of a MOF.
2021
Coordination polymers (CPs), including metal–organic frameworks (MOFs), are crystalline materials with promising applications in electronics, magnetism, catalysis, and gas storage/separation. However, the mechanisms and pathways underlying their formation remain largely undisclosed. Herein, we demonstrate that diffusion-controlled mixing of reagents at the very early stages of the crystallization process (i.e., within ≈40 ms), achieved by using continuous-flow microfluidic devices, can be used to enable novel crystallization pathways of a prototypical spin-crossover MOF towards its thermodynamic product. In particular, two distinct and unprecedented nucleation-growth pathways were experimen…
Photocatalytic CO2 reduction in gas–solid regime in the presence of H2O by using GaP/TiO2 composite as photocatalyst under simulated solar light
2014
GaP/TiO2 composites exhibited a remarkable photocatalytic activity for CO2 reduction in the presence of water vapor producing methane. By decreasing the GaP:TiO2 mass ratio an increase in the photocatalytic activity of the composite was observed for up to a 1:10 mass ratio. The photocatalytic activity of the composite can be attributed to the band structures of the solids as well as to the efficient charge transfer between GaP and TiO2 heterojunction.
Towards the electrochemical conversion of CO2 to formic acid at an applicative scale: technical and economic analysis of most promising routes
2021
In the last decade, the electrochemical conversion of CO 2 to formic acid, FA, using Sn‐based cathodes, was widely investigated. In this work, the technical feasibility and economic viability of this process were evaluated considering the most promising electrochemical routes reported in the literature. Five case studies, based on the utilisation of GDE technologies or high CO 2 pressures, were analysed. The cost for producing FA by the electrochemical route was compared with that of the conventional chemical route. Several scenarios were envisioned finding the target figures of merit, the potential bottlenecks (including low FA concentration, GDE cost and high energy consumption) of each t…
ELECTRON-PHONON COUPLING IN HEAVILY DOPED SILICON
2001
The coupling constant in electron-phonon interaction is a very important issue in nanoscale applications. We have measured this constant in heavily doped silicon. Electron-phonon interaction is proportional to T6 and the coupling constant is found to be 1.5 × 108 W/K5m³, which is about one tenth of the value in normal metals.
Evaluation of Gallium Nitride Transistors in Electronic Power Conditioners for TWTAs
2015
The aim of this paper is to evaluate the benefits of replacing Si Mosfets transistors with enhancement mode GaN transistors in a Half-Bridge Zero Voltage and Zero Current Switching Power Switching Converter (ZVZCPS). This converter is usually used as power supply of the travelling-wave tube amplifiers (TWTAs) in aerospace applications. In this paper, firstly the converter is theoretically analyzed, obtaining its operation, losses and efficiency equations, these equations are used to obtain optimizations maps based on the main system parameters. In this way, the ideal design parameters can be visually obtained. These optimization maps are the key to quantify the potential benefits of GaN tra…
System Design Rules for Intensifying the Electrochemical Reduction of CO 2 to CO on Ag Nanoparticles
2020
Electroreduction of CO2 (eCO2RR) is a potentially sustainable approach for carbon-based chemical production. Despite significant progress, performing eCO2RR economically at scale is challenging. Here we report meeting key technoeconomic benchmarks simultaneously through electrolyte engineering and process optimization. A systematic flow electrolysis study - performing eCO2RR to CO on Ag nanoparticles as a function of electrolyte composition (cations, anions), electrolyte concentration, electrolyte flow rate, cathode catalyst loading, and CO2 flow rate - resulted in partial current densities of 417 and 866 mA/cm2 with faradaic efficiencies of 100 and 98 % at cell potentials of −2.5 and −3.0 …
The guarded fragment with transitive guards
2004
The guarded fragment with transitive guards, (GF+TG), is an extension of the guarded frag- ment of 9rst-order logic, GF, in which certain predicates are required to be transitive, transitive predicate letters appear only in guards of the quanti9ers and the equality symbol may appear everywhere. We prove that the decision problem for (GF+TG) is decidable. Moreover, we show that the problem is in 2EXPTIME. This result is optimal since the satis9ability problem for GF is 2EXPTIME-complete (J. Symbolic Logic 64 (1999) 1719-1742). We also show that the satis- 9ability problem for two-variable (GF+TG) is NEXPTIME-hard in contrast to GF with bounded number of variables for which the satis9ability …