The main goal of successful gene selection for microarray data is to find compact and predictive gene subsets which could improve the accuracy. Though a large pool of available methods exists, ...selecting the optimal gene subset for accurate classification is still very challenging for the diagnosis and treatment of cancer.
To obtain the most predictive genes subsets without filtering out critical genes, a gene selection method based on least absolute shrinkage and selection operator (LASSO) and an improved binary particle swarm optimization (BPSO) is proposed in this paper. To avoid overfitting of LASSO, the initial gene pool is divided into clusters based on their structure. LASSO is then employed to select high predictive genes and further calculate the contribution value which indicates the genes' sensitivity to samples' classes. With the second-level gene pool established by double filter strategy, the BPSO encoding the contribution information obtained from LASSO is improved to perform gene selection. Moreover, from the perspective of the bit change probability, a new mapping function is defined to guide the updating of the particle to select the more predictive genes in the improved BPSO.
With the compact gene pool obtained by double filter strategies, the improved BPSO could select the optimal gene subsets with high probability. The experimental results on several public microarray data with extreme learning machine verify the effectiveness of the proposed method compared to the relevant methods.
The electrochemical N2 fixation, which is far from practical application in aqueous solution under ambient conditions, is extremely challenging and requires a rational design of electrocatalytic ...centers. We observed that bismuth (Bi) might be a promising candidate for this task because of its weak binding with H adatoms, which increases the selectivity and production rate. Furthermore, we successfully synthesized defect‐rich Bi nanoplates as an efficient noble‐metal‐free N2 reduction electrocatalyst via a low‐temperature plasma bombardment approach. When exclusively using 1H NMR measurements with N2 gas as a quantitative testing method, the defect‐rich Bi(110) nanoplates achieved a 15NH3 production rate of 5.453 μg mgBi−1 h−1 and a Faradaic efficiency of 11.68 % at −0.6 V vs. RHE in aqueous solution at ambient conditions.
Beneficial defects: Defect‐rich bismuth nanoplates achieve a 15NH3 production rate of 5.453 μg mgBi−1 h−1 and a Faradaic efficiency of 11.68 % at −0.6 V vs. RHE in aqueous solutions at ambient conditions because of their poor binding with H adatoms, which increases the selectivity and production rate. Also, 1H NMR measurements with N2 gas ware used as a quantitative test method in aqueous electrolytes.
Multi‐emission materials have come to prominent attention ascribed to their extended applications other than single‐emission ones. General and robust design strategies of a single matrix with ...multi‐emission under single excitation are urgently required. Metal–organic frameworks (MOFs) are porous materials prepared with organic ligands and metal nodes. The variety of metal nodes and ligands makes MOFs with great superiority as multi‐emission matrices. Guest species encapsulated into the channels or pores of MOFs are the additional emission sites for multi‐emission. In this review, multi‐emission MOFs according to the different excitation sites are summarized and classified. The emission mechanisms are discussed, such as antenna effect, excited‐state intramolecular proton transfer (ESIPT) and tautomerism for dual‐emission. The factors that affect the emissions are revealed, including ligand–metal energy transfer and host–guest interaction, etc. Multi‐emission MOFs could be predictably designed and prepared, once the emissive factors are controlled rationally in combination with the different multi‐emission mechanisms. Correspondingly, new and practical applications are realized, including but not limited to ratiometric/multi‐target sensing and bioimaging, white light–emitting diodes, and anti‐counterfeiting. The design strategies of multi‐emission MOFs and their extensive applications are reviewed. The results will shed light on other multi‐emission systems to develop the structure‐derived functionality and applications.
The variety of metal nodes, ligands, and guest molecules provide the potential emission centers to endow metal–organic frameworks (MOFs) with great potential as a multi‐emission matrix. In this review, the multi‐emission MOFs excited under a single wavelength are summarized and classified according to the different excitation sites. Furthermore, the design concept, and application of multi‐emission MOFs are summarized.
Electrocatalytic hydrogen evolution in alkaline and neutral media offers the possibility of adopting platinum‐free electrocatalysts for large‐scale electrochemical production of pure hydrogen fuel, ...but most state‐of‐the‐art electrocatalytic materials based on nonprecious transition metals operate at high overpotentials. Here, a monolithic nanoporous multielemental CuAlNiMoFe electrode with electroactive high‐entropy CuNiMoFe surface is reported to hold great promise as cost‐effective electrocatalyst for hydrogen evolution reaction (HER) in alkaline and neutral media. By virtue of a surface high‐entropy alloy composed of dissimilar Cu, Ni, Mo, and Fe metals offering bifunctional electrocatalytic sites with enhanced kinetics for water dissociation and adsorption/desorption of reactive hydrogen intermediates, and hierarchical nanoporous Cu scaffold facilitating electron transfer/mass transport, the nanoporous CuAlNiMoFe electrode exhibits superior nonacidic HER electrocatalysis. It only takes overpotentials as low as ≈240 and ≈183 mV to reach current densities of ≈1840 and ≈100 mA cm−2 in 1 m KOH and pH 7 buffer electrolytes, respectively; ≈46‐ and ≈14‐fold higher than those of ternary CuAlNi electrode with bimetallic Cu–Ni surface alloy. The outstanding electrocatalytic properties make nonprecious multielemental alloys attractive candidates as high‐performance nonacidic HER electrocatalytic electrodes in water electrolysis.
Nonprecious nanoporous multielemental alloy electrodes composed of electroactive surface high‐entropy CuNiMoFe alloy hold great promise as cost‐effective electrocatalysts for hydrogen evolution reaction (HER) in nonacidic media. Associated with hierarchical nanoporous architecture to facilitate electron transfer and offer abundant high‐entropy CuNiMoFe active sites, the nanoporous CuAlNiMoFe hybrid electrode exhibits remarkably enhanced HER activity and durability.
Although single-atomically dispersed metal-N
on carbon support (M-NC) has great potential in heterogeneous catalysis, the scalable synthesis of such single-atom catalysts (SACs) with high-loading ...metal-N
is greatly challenging since the loading and single-atomic dispersion have to be balanced at high temperature for forming metal-N
. Herein, we develop a general cascade anchoring strategy for the mass production of a series of M-NC SACs with a metal loading up to 12.1 wt%. Systematic investigation reveals that the chelation of metal ions, physical isolation of chelate complex upon high loading, and the binding with N-species at elevated temperature are essential to achieving high-loading M-NC SACs. As a demonstration, high-loading Fe-NC SAC shows superior electrocatalytic performance for O
reduction and Ni-NC SAC exhibits high electrocatalytic activity for CO
reduction. The strategy paves a universal way to produce stable M-NC SAC with high-density metal-N
sites for diverse high-performance applications.
Hardware implementation of artificial synaptic devices that emulate the functions of biological synapses is inspired by the biological neuromorphic system and has drawn considerable interest. Here, a ...three‐terminal ferrite synaptic device based on a topotactic phase transition between crystalline phases is presented. The electrolyte‐gating‐controlled topotactic phase transformation between brownmillerite SrFeO2.5 and perovskite SrFeO3−δ is confirmed from the examination of the crystal and electronic structure. A synaptic transistor with electrolyte‐gated ferrite films by harnessing gate‐controllable multilevel conduction states, which originate from many distinct oxygen‐deficient perovskite structures of SrFeOx induced by topotactic phase transformation, is successfully constructed. This three‐terminal artificial synapse can mimic important synaptic functions, such as synaptic plasticity and spike‐timing‐dependent plasticity. Simulations of a neural network consisting of ferrite synaptic transistors indicate that the system offers high classification accuracy. These results provide insight into the potential application of advanced topotactic phase transformation materials for designing artificial synapses with high performance.
A ferrite synaptic transistor with topotactic transformation is presented. The electrolyte‐gating‐controlled topotactic phase transformation between the brownmillerite SrFeO2.5 and perovskite SrFeO3−δ is confirmed by the crystal and electronic structure measurements. This ferrite synaptic transistor can mimic important synaptic functions such as synaptic plasticity and spike‐timing‐dependent plasticity.
Since it was confirmed two decades ago that the expansion of the Universe is accelerating, it would be of theoretical interests to figure out what is the influence from cosmological constant on ...detection of stochastic gravitational wave background. This paper studies the overlap reduction functions in de-Sitter space-time for a pair of one-way tracking gravitational wave detectors. It is shown to be non-trivial in an expanding Universe, because the propagation of light along line of sight also has effect on the response of GW detectors. It is found that the expansion of the Universe can enhance the value of magnitude of the overlap reduction functions, when the detector pairs are close to each other. For nanohertz gravitational waves, this effect can dominate the values of overlap reduction functions when the galactic pulsar pairs are separated by milliarcsecond.
Abstract
In this paper, the standard and the localized space‐time radial basis function (RBF) collocation methods are modified and combined with the time‐marching scheme and space‐time domain ...decomposition technique for simulating the long‐time transient heat conduction in 3D anisotropic composite materials. In the proposed approaches, we set the source points outside the whole space‐time domain in the standard space‐time RBF collocation method or outside the established subdomain in the localized approach by introducing the space and time magnification factors, instead of distributing them inside the original domain. In addition, the space‐time regulating factor is defined and added to the conventional schemes to improve the stability of numerical methods. The modified approaches are resulted in a simple and effective time‐marching process which can achieve long‐time simulation, resting on the property that the coefficient matrices generated by these two methods are only related to the space‐time distance between the collocation points and source points. Our ultimate aim is to develop a computing system for resolving dynamic problems in composite materials by designing a space‐time domain decomposition technique. Numerical experiments are conducted to demonstrate the accuracy, efficiency and stability of the presented methodologies.
Efficient and selective dehydrogenation of formic acid is a key challenge for a fuel‐cell‐based hydrogen economy. Though the development of heterogeneous catalysts has received much progress, their ...catalytic activity remains insufficient. Moreover, the design principle of such catalysts are still unclear. Here, experimental and theoretical studies on a series of mono‐/bi‐metallic nanoparticles supported on a NH2‐N‐rGO substrate are combined for formic acid dehydrogenation where the surface energy of a metal is taken as a relevant indicator for the adsorption ability of the catalyst for guiding catalyst design. The AuPd/NH2‐N‐rGO catalyst shows record catalytic activity by reducing the energy barrier of rate controlling steps of formate adsorption and hydrogen desorption. The obtained excellent results both in experiments and simulations could be extended to other important systems, providing a general guideline to design more efficient catalysts.
A AuPd/NH2‐N‐rGO catalyst shows supreme catalytic performance for the decomposition of formic acid at room temperature, with a turnover frequency (TOF) of 4445.6 h−1. Developments in the experiments and simulations of high‐performance catalysts may promote the practical application of formic acid as a promising hydrogen storage material.
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