•A convenient fabrication method for making microfluidic electrodes and substrates.•Well-developed recipes for making Ni, Ag, Pd, Pt electrodes for electrocatalysis.•PCB-based reference electrodes ...that facilitate devices miniaturizations.
As a chemically resistant hard substrate with surface-mounted metal pads, Printed Circuit Boards (PCBs) have the potential to be utilized as substrates for electrochemical applications such as electrochemical microfluidic devices. Compared with regular electrochemical substrates made with glass slides or filter papers, PCB-based substrates have electrode pads with customized size, shape and position, and more wiring layers. Previous works have shown that the PCB-based electrochemical devices can be used as biosensors, electrochemical impedance cytometers, and electrochemical imaging platforms, while their workability as a platform for electrocatalysis has not yet been presented. This work presents a method to develop PCBs into electrochemical substrates for alcohol electrocatalysis and internal reference electrodes. The copper pads were pretreated and electrodeposited with nickel (Ni), silver (Ag), palladium (Pd), and platinum (Pt) for various electrocatalytic purposes. To show the ability of making PCB-based electrochemical devices, two types of PCB-based reference electrodes were made.
Selenium is a semimetallic element lying in group XVI of the periodic table with its chemical properties resembling sulfur. But owing to its relatively low electronegativity and large atomic radius ...compared with sulfur, selenium also shows unique properties. This feature endows selenium-containing compounds with high reactivity and sensitivity. Although organic selenium chemistry has been developing very fast, the successful introduction of selenium into polymer science is rather scarce. Fortunately, we have seen a drastic rising trend in the area of selenium-containing polymers over the past decade. In this Perspective, the synthetic routes of selenium-containing polymers are summarized, and their unique stimuli-responsive properties are elaborated on, together with their diverse applications in the field of adaptive and biomedical materials.
In the most recent decade, glycerol electrooxidation (GEOR) has attracted extensive research interest for valorization of glycerol: the conversion of glycerol to value‐added products. These reactions ...at platinum, palladium, and gold electrodes have a lot of uncertainty in their reaction mechanisms, which has generated some controversies. This review gathers many reported experimental results, observations and proposed reaction mechanisms in order to draw a full picture of GEOR. A particular focus is the clarification of two propositions: Pd is inferior to Pt in cleaving the C−C bonds of glycerol during the electrooxidation and the massive production of CO2 at high overpotentials is due to the oxidation of the already‐oxidized carboxylate products. It is concluded that the inferior C−C bond cleavability with Pd electrodes, as compared with Pt electrodes, is due to the inefficiency of deprotonation, and the massive generation of CO2 as well as other C1/C2 side products is partially caused by the consumption of OH– at the anodes, as a lower pH reduces the amount of carboxylates and favors the C−C bond scission. A reaction mechanism is proposed in this review, in which the generation of side products are directly from glycerol (“competition” between each side product) rather than from the further oxidation of C2/C3 products. Additionally, GEOR results and associated interpretations for Ni electrodes are presented, as well as a brief review on the performances of multi‐metallic electrocatalysts (most of which are nanocatalysts) as an introduction to these future research hotpots.
The valorization of glycerol through its electrooxidation has been widely conducted with Pt, Pd, and Au electrodes. However, the controversies brought by reported experimental results prevent us from understanding the reaction mechanisms. This Review summarizes key observations of glycerol electrooxidation at these electrodes, and proposed new reaction pathways.
Aqueous Zn‐ion batteries own great potential on next generation wearable batteries due to the high safety and low cost. However, the uncontrollable dendrites growth and the negligible subzero ...temperature performance impede the batteries practical applications. Herein, it is demonstrated that dimethyl sulfoxide (DMSO) is an effective additive in ZnSO4 electrolyte for side reactions and dendrites suppression by regulating the Zn‐ion solvation structure and inducing the Zn2+ to form the more electrochemical stable (002) basal plane, via the higher absorption energy of DMSO with Zn2+ and (002) plane. Moreover, the stable reconstructed hydrogen bonds between DMSO and H2O dramatically lower the freezing point of the electrolyte, which significantly increases the ionic conductivity and cycling performance of the aqueous batteries at subzero temperatures. As a consequence, the symmetrical Zn/Zn cell can be kept stable for more than 2100 h at 20 °C and 1200 h at −20 °C without dendrite and by‐products formation. The Zn/MnO2 batteries can perform steadily for more than 3000 cycles at 20 °C and 300 cycles at −20 °C. This work provides a facile and feasible strategy on designing high performance and dendrite free aqueous Zn‐ion batteries for various temperatures.
The dimethyl sulfoxide (DMSO) molecule can help to optimize the Zn2+ deposition behavior by inducing the fine‐grained Zn nucleation with higher overpotential, and texturing the growth of the electrochemically stable hexagonal (002) plane. In addition, the reconstructed strong hydrogen bonds between DMSO and H2O further alleviate side reactions and endow the battery subzero temperature performance.
Abstract
Topological phases characterized by non-Abelian charges are beyond the scope of the paradigmatic tenfold way and have gained increasing attention recently. Here we investigate topological ...insulators with multiple tangled gaps in Floquet settings and identify uncharted Floquet non-Abelian topological insulators without any static or Abelian analog. We demonstrate that the bulk-edge correspondence is multifold and follows the multiplication rule of the quaternion group
Q
8
. The same quaternion charge corresponds to several distinct edge-state configurations that are fully determined by phase-band singularities of the time evolution. In the anomalous non-Abelian phase, edge states appear in all bandgaps despite trivial quaternion charge. Furthermore, we uncover an exotic swap effect—the emergence of interface modes with swapped driving, which is a signature of the non-Abelian dynamics and absent in Floquet Abelian systems. Our work, for the first time, presents Floquet topological insulators characterized by non-Abelian charges and opens up exciting possibilities for exploring the rich and uncharted territory of non-equilibrium topological phases.
Rock music is an integral part of American culture. This paper presents a study of sensing and analysing over 57,000 rock music live performances between 2007 and 2017. Spatial traces of 575 rock ...music artists performing in concerts nationwide were collected from a major music streaming platform Spotify. Location-based concert data were analysed to explore economic and geographic factors linked to the landscape of rock music live performance and to reveal the importance of population demographics and leisure and hospitality (LH) economics to the culture and music industries from a spatial aspect. Over 90% of rock concerts between 2007 and 2017 were found in 250 counties. The aim of the study is to specify and develop a model that reasonably accounts for spatial heterogeneity present in the concert data. By regressing rock concert data against demographic data and LH establishment data, ordinary least squares (OLS) models were better fitted in metropolitan counties than non-metropolitan counties. Spatial dynamics of concerts were revealed by local R
2
values and the obtained structure in the form of spatial heterogeneity was then explained using geographically weighted regression (GWR) models. High population density and LH services in industry-leading cities such as New York City, Los Angeles, Chicago and Houston exhibit advantages in explaining rock concert distributions. Findings from the models reflect the live music industry's interrelationships to the LH industry and suggest LH services being essential considerations in selecting concert destinations for rock musicians.
Photorealistic frontal view synthesis from a single face image has a wide range of applications in the field of face recognition. Although data-driven deep learning methods have been proposed to ...address this problem by seeking solutions from ample face data, this problem is still challenging because it is intrinsically ill-posed. This paper proposes a Two-Pathway Generative Adversarial Network (TP-GAN) for photorealistic frontal view synthesis by simultaneously perceiving global structures and local details. Four landmark located patch networks are proposed to attend to local textures in addition to the commonly used global encoder-decoder network. Except for the novel architecture, we make this ill-posed problem well constrained by introducing a combination of adversarial loss, symmetry loss and identity preserving loss. The combined loss function leverages both frontal face distribution and pre-trained discriminative deep face models to guide an identity preserving inference of frontal views from profiles. Different from previous deep learning methods that mainly rely on intermediate features for recognition, our method directly leverages the synthesized identity preserving image for downstream tasks like face recognition and attribution estimation. Experimental results demonstrate that our method not only presents compelling perceptual results but also outperforms state-of-the-art results on large pose face recognition.
Heteroatom doping is an effective way to adjust the fluorescent properties of carbon quantum dots. However, selenium‐doped carbon dots have rarely been reported, even though selenium has unique ...chemical properties such as redox‐responsive properties owing to its special electronegativity. Herein, a facile and high‐output strategy to fabricate selenium‐doped carbon quantum dots (Se‐CQDs) with green fluorescence (quantum yield 7.6 %) is developed through the hydrothermal treatment of selenocystine under mild conditions. Selenium heteroatoms endow the Se‐CQDs with redox‐dependent reversible fluorescence. Furthermore, free radicals such as .OH can be effectively scavenged by the Se‐CQDs. Once Se‐CQDs are internalized into cells, harmful high levels of reactive oxygen species (ROS) in the cells are decreased. This property makes the Se‐CQDs capable of protecting biosystems from oxidative stress.
Hydrothermal treatment of selenocystine enabled selenium‐doped carbon quantum dots (Se‐CQDs) with redox‐dependent reversible fluorescence and free radical‐scavenging capability to be fabricated. Once Se‐CQDs are internalized into cells, harmful high levels of reactive oxygen species (ROS) in the cells are decreased. This property makes the Se‐CQDs capable of protecting biosystems from oxidative stress.
In this paper, a pipe element is developed for a pipe structure with variable wall thickness. The variable wall thickness field tw can be an arbitrary function about circumferential and axial ...directions. A local dimensionless cylindrical coordinate system is set up. The displacement expression is defined based on the local dimensionless cylindrical coordinate system. The map from the local dimensionless cylindrical coordinate system to the pipe structure configuration is established. In the circumferential and radial dimensions, the series is used as the displacement basis functions. In the axial direction, Lagrangian interpolation is applied. Furthermore, the referential surface R can also be defined as an arbitrary function about circumferential and axial directions as tw. Thus, this pipe element has wide applications. The complicated problems with geometrical nonlinearity (large deformation and finite strain) can be analyzed well by this element. The pipe buckle crossover problem is analyzed in this paper. In this problem, the pipe model has an axially variable wall thickness field. The eccentric pipe collapse problem is also analyzed. In this problem, the pipe model has a circumferential variable wall thickness field. The results are compared with those from other well-established FEM simulations.
•A variable wall thickness pipe element is developed for pipe structure with a variable wall thickness field. The wall-thickness can be an arbitrary function about circumferential and axial directions.•High order interpolation and continuity are obtained.•The pipe buckle crossover problem is analyzed by this element. The results are compared with other papers.
Dielectric ceramics with outstanding energy-storage performances are nowadays in great demand for pulsed power electronic systems. Here, we propose a synergistic design strategy to significantly ...enhance the energy-storage properties of (1 – x)(0.94Na0.5Bi0.5TiO3-0.06BaTiO3)-xCaTi0.75Ta0.2O3 solid solution ceramics through introducing polar nanoregions, shifting rhombohedral to tetragonal phase transition below room temperature (stable antiferroelectric characteristic), as well as increasing the band gap in the system. Ultrahigh energy-storage properties with a record value of recoverable energy-storage density W rec ∼ 9.55 J/cm3 and a high efficiency η ∼ 88% are achieved in Na0.5Bi0.5TiO3-based bulk ceramics with x = 0.24. Moreover, high W rec (>3.4 J/cm3) and η (>90%) with a variation of less than 6% can be observed in a wide frequency and temperature frequency range of 5–200 Hz and 25–140 °C. Our research result not only indicates the great possibility of Na0.5Bi0.5TiO3-based lead-free compositions to replace lead-based energy-storage ceramics but also gives an effective strategy to design ultrahigh energy-storage performances for eco-friendly ceramics.
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