Nervonic acid (NA) is a major very long-chain monounsaturated fatty acid found in the white matter of mammalian brains, which plays a critical role in the treatment of psychotic disorders and ...neurological development. In the nature, NA has been synthesized by a handful plants, fungi, and microalgae. Although the metabolism of fatty acid has been studied for decades, the biosynthesis of NA has yet to be illustrated. Generally, the biosynthesis of NA is considered starting from oleic acid through fatty acid elongation, in which malonyl-CoA and long-chain acyl-CoA are firstly condensed by a rate-limiting enzyme 3-ketoacyl-CoA synthase (KCS). Heterologous expression of
kcs
gene from high NA producing species in plants and yeast has led to synthesis of NA. Nevertheless, it has also been reported that desaturases in a few plants can catalyze very long-chain saturated fatty acid into NA. This review highlights recent advances in the biosynthesis, the sources, and the biotechnological aspects of NA.
Electrocatalysts are the core components of many sustainable energy conversion technologies that are considered the most potential solution to the worldwide energy and environmental crises. The ...reliability of structure and composition pledges that electrocatalysts can achieve predictable and stable performance. However, during the electrochemical reaction, electrocatalysts are influenced directly by the applied potential, the electrolyte, and the adsorption/desorption of reactive species, triggering structural and compositional corrosion, which directly affects the catalytic behaviors of electrocatalysts (performance degradation or enhancement) and invalidates the established structure–activity relationship. Therefore, it is necessary to elucidate the corrosion behavior and mechanism of electrocatalysts to formulate targeted corrosion‐resistant strategies or use corrosion reconstruction synthesis techniques to guide the preparation of efficient and stable electrocatalysts. Herein, the most recent developments in electrocatalyst corrosion chemistry are outlined, including corrosion mechanisms, mitigation strategies, and corrosion syntheses/reconstructions based on typical materials and important electrocatalytic reactions. Finally, potential opportunities and challenges are also proposed to foresee the possible development in this field. It is believed that this contribution will raise more awareness regarding nanomaterial corrosion chemistry in energy technologies and beyond.
Corrosion chemistry of electrocatalysts is reviewed, which may inspire more profound research in functional nanomaterials and energy technologies.
Cardiac fibrosis is characterized by excessive extracellular matrix deposition that contributes to compromised cardiac function and potentially heart failure. Cardiac pressure overload resulting from ...trans-aortic constriction in mice leads to cardiac fibrosis and increased Wnt/β-catenin signaling in cardiac fibroblasts. Here, we conditionally induce β-catenin loss of function in resident cardiac fibroblasts using Tcf21
or in activated cardiac fibroblasts using periostin (Postn)
. We show that β-catenin loss of function in cardiac fibroblasts after trans-aortic constriction significantly preserves cardiac function, and reduces interstitial fibrosis but does not alter the numbers of activated or differentiated cardiac fibroblasts in vivo. However, β-catenin is specifically required in resident cardiac fibroblasts for fibrotic excessive extracellular matrix gene expression and binds Col3a1 and Postn gene sequences in cultured cardiac fibroblasts after induction of Wnt signaling. Moreover, cardiomyocyte hypertrophy is blunted with cardiac fibroblast-specific loss of β-catenin after trans-aortic constriction in vivo. Thus, Wnt/β-catenin signaling in resident cardiac fibroblasts is required for excessive extracellular matrix gene expression and collagen deposition after trans-aortic constriction.Understanding the mechanisms causing cardiac fibrosis is key to prevention and therapy development of many heart diseases. Here, the authors show that Wnt/β-catenin signaling in resident cardiac fibroblasts is required for deposition of fibrotic extracellular matrix and the regulation of cardiomyocyte hypertrophy in a mouse model of heart fibrosis.
Exploring a cheap and clean renewable energy has become a common destination round the world with the depletion of oil resources and the concerns of increasing energy demands. Lignocellulosic biomass ...is the most abundant renewable resource in the biosphere, and the total biomass formed by plant photosynthesis reached more than 200 billion tons every year. Cellulase and hemicellulose and lignin degradation enzymes, the efficient biocatalyst, could efficiently convert the lignocellulosic biomass into sugars that could be further processed into biofuels, biochemical, and biomaterial for human requirement. The utilization and conversion of cellulosic biomass has great significance to solve the problems such as environmental pollution and energy crisis. Lignocellulosic materials are widely considered as important sources to produce sugar streams that can be fermented into ethanol and other organic chemicals. Pretreatment is a necessary step to overcome its intrinsic recalcitrant nature prior to the production of important biomaterial that has been investigated for nearly 200 years. Emerging research has focused in order of economical, eco-friendly, and time-effective solutions, for large-scale operational approach. These new mentioned technologies are promising for lignocellulosic biomass degradation in a huge scale biorefinery. This review article has briefly explained the emerging technologies especially the consolidated bioprocessing, chemistry, and physical base pretreatment and their importance in the valorization of lignocellulosic biomass conversion.
Fuel cells are considered as a promising alternative to the existing traditional energy systems towards a sustainable future. Nevertheless, the synthesis of efficient and robust platinum (Pt) based ...catalysts remains a challenge for practical applications. In this work, we present a simple and scalable molten‐salt synthesis method for producing a low‐platinum (Pt) nanoalloy implanted in metal–nitrogen–graphene. The as‐prepared low‐Pt alloyed graphene exhibits a high oxygen reduction activity of 1.29 A mgPt−1 and excellent durability over 30 000 potential cycles. The catalyst nanoarchitecture of graphene encased Pt nanoalloy provides a robust capability against nanoparticle migration and corrosion due to a strong metal–support interaction. Similarly, advanced characterization and theoretical calculations show that the multiple active sites in platinum alloyed graphene synergistically account for the improved oxygen reduction. This work not only provides an efficient and robust low‐Pt catalyst but also a facile design idea and scalable preparation technique for integrated catalysts to achieve more profound applications in fuel cells and beyond.
Pt−Co nanoalloys planted in the metal–nitrogen–graphene system achieved by a scalable molten salt pyrolysis method demonstrate improved activity and stability for oxygen reduction through a synergistic effect among multiple active sites and a strong metal–support interaction.
The data-driven methods in machinery fault diagnosis have become increasingly popular in the past two decades. However, the wide applications of this scheme are generally compromised in real-world ...conditions because of the discrepancy between the training data and testing data. Although the recently emerging transfer fault diagnosis can learn transferable features from relevant source data and adapt the diagnostic model to the target data, these methods still only work on the target domain with a priori data distribution. The generalization capability of the transferred model cannot be guaranteed for unseen domains. Since the working conditions of machinery are varying during operation, the generalization capability of the diagnosis methods is crucial in this case. To tackle this challenge, this article proposes a domain generalization-based hybrid diagnosis network for deploying to unseen working conditions. The main idea is to regularize the discriminant structure of the deep network with both intrinsic and extrinsic generalization objectives such that the diagnostic model can learn robust features and generalize to unseen domains. The triplet loss minimization of intrinsic multisource data is implemented to facilitate the intraclass compactness and the interclass separability at the class level, leading to a more generalized decision boundary. The extrinsic domain-level regularization is achieved by using adversarial training to further reduce the risk of overfitting. Extensive cross-domain diagnostic experiments on planetary gearbox demonstrate the effectiveness of the proposed method.
Recently, higher-order topological phases that do not obey the usual bulk-edge correspondence principle have been introduced in electronic insulators and brought into classical systems, featuring ...in-gap corner or hinge states. In this Letter, using near-field scanning measurements, we show the direct observation of corner states in second-order topological photonic crystal slabs consisting of periodic dielectric rods on a perfect electric conductor. Based on the generalized two-dimensional Su-Schrieffer-Heeger model, we show that the emergence of corner states roots in the nonzero edge dipolar polarization instead of the nonzero bulk quadrupole polarization. We demonstrate the topological transition of two-dimensional Zak phases of photonic crystal slabs by tuning intracell distances between two neighboring rods. We also directly observe in-gap one-dimensional edge states and zero-dimensional corner states in the microwave regime. Our work presents that the photonic crystal slab is a powerful platform to directly observe topological states and paves the way to study higher-order photonic topological insulators.
Gauge magnetic fields have a close relation to breaking time-reversal symmetry in condensed matter. In the presence of the gauge fields, we might observe nonreciprocal and topological transport. ...Inspired by these, there is a growing effort to realize exotic transport phenomena in optical and acoustic systems. However, due to charge neutrality, realizing analog magnetic flux for phonons in nanoscale systems is still challenging in both theoretical and experimental studies. Here we propose a novel mechanism to generate synthetic magnetic field for phonon lattice by Floquet engineering auxiliary qubits. We find that, a longitudinal Floquet drive on the qubit will produce a resonant coupling between two detuned acoustic cavities. Specially, the phase encoded into the longitudinal drive can exactly be transformed into the phonon-phonon hopping. Our proposal is general and can be realized in various types of artificial hybrid quantum systems. Moreover, by taking surface-acoustic-wave (SAW) cavities for example, we propose how to generate synthetic magnetic flux for phonon transport. In the presence of synthetic magnetic flux, the time-reversal symmetry will be broken, which allows one to realize the circulator transport and analog Aharonov-Bohm effects for acoustic waves. Last, we demonstrate that our proposal can be scaled to simulate topological states of matter in quantum acoustodynamics system.
Backscattering suppression in silicon-on-insulator (SOI) is one of the central issues to reduce energy loss and signal distortion, enabling for capability improvement of modern information processing ...systems. Valley physics provides an intriguing way for robust information transfer and unidirectional coupling in topological nanophotonics. Here we realize topological transport in a SOI valley photonic crystal slab. Localized Berry curvature near zone corners guarantees the existence of valley-dependent edge states below light cone, maintaining in-plane robustness and light confinement simultaneously. Topologically robust transport at telecommunication is observed along two sharp-bend interfaces in subwavelength scale, showing flat-top high transmission of ~10% bandwidth. Topological photonic routing is achieved in a bearded-stack interface, due to unidirectional excitation of valley-chirality-locked edge state from the phase vortex of a nanoscale microdisk. These findings show the prototype of robustly integrated devices, and open a new door towards the observation of non-trivial states even in non-Hermitian systems.
Palladium (Pd) nanostructures are highly active non‐platinum anodic electrocatalysts in alkaline direct methanol fuel cells (ADMFCs) and their electrocatalytic performance relies highly on their ...morphology and composition. Herein, a facile high‐temperature pyrolysis method to synthesize high‐quality Pd‐palladium oxide (PdO) porous nanotubes (PNTs) by using Pd(II)‐dimethylglyoxime complex (Pd(II)‐DMG) nanorods as a self‐template is reported. The chemical component of pyrolysis products highly correlates with pyrolysis temperature. The electrochemical measurements and density functional theory calculations show the existence of PdO enhances the electroactivity of metallic Pd for both methanol oxidation reaction (MOR) and carbon monoxide oxidation reaction in alkaline media. Benefiting from its one‐dimensionally porous architecture and evident synergistic effect between PdO and Pd (e.g., electronic effect and bifunctional mechanism), Pd‐PdO PNTs achieve a 3.7‐fold mass activity enhancement and improved durability for MOR compared to commercial Pd nanocrystals. Considering the simple synthesis, excellent activity, and long‐term stability, Pd‐PdO PNTs may be highly promising anodic electrocatalysts in ADMFCs.
High‐quality porous palladium (Pd)‐palladium oxide (PdO) nanotubes are synthesized via a facial Pd(II)‐dimethylglyoxime complex nanorods‐induced self‐template method. Benefiting from the one‐dimensionally porous architecture and evident synergistic effect between PdO and Pd, the Pd‐PdO nanotubes achieve a 3.7‐fold mass activity enhancement and improved durability for methanol oxidation reaction compared to commercial Pd nanocrystals, revealing a highly promising robust anodic electrocatalyst in alkaline direct methanol fuel cells.
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