Three‐dimensional (3D) printing, also known as additive manufacturing, is a fabrication method that has recently received worldwide attention. It provides a convenient and economical way to prepare ...3D structures in designable ways. As the technology has developed and the operational costs have decreased, the applications of 3D printing have greatly expanded. Catalyst fabrication is a promising area for 3D printing. Printing processes result in better control of catalyst structures and catalyst distribution. In this perspective, a general overview of the commonly available 3D printing methods that are feasible for the preparation of heterogeneous catalysts is given. Additionally, recent works on printing strategies and new materials for catalysts are discussed. Future development is also addressed.
Three‐dimensional (3D) printing is a fabrication method that has received worldwide attention. Recently, 3D printing has been applied to catalyst fabrication. In this perspective, a general overview of the commonly available 3D printing methods that are feasible for the preparation of heterogeneous catalysts is given. Recent works on printing strategies and new materials for catalysts are discussed. Future development is also addressed.
Solar vapor generation is a facile and an efficient way for solar energy harvesting, which is applied to address the issue of fresh water extraction from sewage or brine. Several solar vapor ...generation devices have been developed in the past few years, but the low evaporation rate still remains as a challenge. In this work, a novel double‐layer solar vapor generation device, named as Ag‐PSS‐AG/AG device, is reported. This device is based on the hierarchical composition of silver nanoparticles (Ag NPs) and poly (sodium‐p‐styrenesulfonate) (PSS) decorated agarose gel (AG). The device reveals a synergetic effect of the two layers with high light‐harvesting and water‐transfer performance, respectively, leading to an ultrahigh vapor generation rate of 2.10 kg m−2 h−1 with a solar thermal efficiency of 92.8% under 1 sun illumination. This high evaporation rate is mainly owing to the powerful light‐thermal conversion of Ag NPs as well as the outstanding water transfer capability of agarose hydrogel. Consequently, this device can be directly used for the purification of sewage and muddy water. It is also promising for applications in separation, humidity management, and others.
A novel double‐layer solar vapor generation device based on the hierarchical composition of silver nanoparticles and agarose gel is designed. With the synergetic effect of the two functional layers, the device exhibits an ultrahigh vapor generation rate of 2.10 kg m−2 h−1 with a solar thermal efficiency of 92.8% under 1 Sun illumination.
Phenylpropanoid biosynthesis in plants engenders a vast variety of aromatic metabolites critically important for their growth, development, and environmental adaptation. Some of these aromatic ...compounds have high economic value. Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in the pathway; it diverts the central flux of carbon from the primary metabolism to the synthesis of myriad phenolics. Over the decades, many studies have shown that exquisite regulatory mechanisms at multiple levels control the transcription and the enzymatic activity of PALs. In this review, a current overview of our understanding of the complicated regulatory mechanisms governing the activity of PAL is presented; recent progress in unraveling its post-translational modifications, its metabolite feedback regulation, and its enzyme organization is highlighted.
Phenylalanine ammonia-lyase (PAL) is the first committed enzyme in phenylpropanoid biosynthesis pathway. It is controlled under a multitude of regulatory mechanisms. In this review, a current overview on our understanding of the complicated regulatory mechanisms governing the activity of PAL is presented.
• Plants produce several hundreds of thousands of secondary metabolites that are important for adaptation to various environmental conditions. Although different groups of secondary metabolites are ...synthesized through unique biosynthetic pathways, plants must orchestrate their production simultaneously. Phenylpropanoids and glucosinolates are two classes of secondary metabolites that are synthesized through apparently independent biosynthetic pathways. Genetic evidence has revealed that the accumulation of glucosinolate intermediates limits phenylpropanoid production in a Mediator Subunit 5 (MED5)-dependent manner.
• To elucidate the molecular mechanism underlying this process, we analyzed the transcriptomes of a suite of Arabidopsis thaliana glucosinolate-deficient mutants using RNAseq and identified misregulated genes that are rescued by the disruption of MED5.
• The expression of a group of Kelch Domain F-Box genes (KFBs) that function in PAL degradation is affected in glucosinolate biosynthesis mutants and the disruption of these KFBs restores phenylpropanoid deficiency in the mutants.
• Our study suggests that glucosinolate/phenylpropanoid metabolic crosstalk involves the transcriptional regulation of KFB genes that initiate the degradation of the enzyme phenylalanine ammonia-lyase, which catalyzes the first step of the phenylpropanoid biosynthesis pathway. Nevertheless, KFB mutant plants remain partially sensitive to glucosinolate pathway mutations, suggesting that other mechanisms that link the two pathways also exist.
Nanoparticle/metal-organic frameworks (MOF) based composites have recently attracted significant attention as a new class of catalysts. Such composites possess the unique features of MOFs (including ...clearly defined crystal structure, high surface area, single site catalyst, special confined nanopore, tunable, and uniform pore structure), but avoid some intrinsic weaknesses (like limited electrical conductivity and lack in the "conventional" catalytically active sites). This review summarizes the developed strategies for the fabrication of nanoparticle/MOF composites for catalyst uses, including the strategy using MOFs as host materials to hold and stabilize the guest nanoparticles, the strategy with subsequent MOF growth/assembly around pre-synthesized nanoparticles and the strategy mixing the precursors of NPs and MOFs together, followed by self-assembly process or post-treatment or post-modification. The applications of nanoparticle/MOF composites for CO oxidation, CO₂ conversion, hydrogen production, organic transformations, and degradation of pollutants have been discussed. Superior catalytic performances in these reactions have been demonstrated. Challenges and future developments are finally addressed.
Flavonoids represent a large family of specialized metabolites involved in plant growth, development, and adaptation. Chalcone synthase (CHS) catalyzes the first step of flavonoid biosynthesis by ...directing carbon flux from general phenylpropanoid metabolism to flavonoid pathway. Despite extensive characterization of its function and transcriptional regulation, the molecular basis governing its posttranslational modification is enigmatic. Here, we report the discovery of a proteolytic regulator of CHS, namely, KFBCHS, a Kelch domain-containing F-box protein in Arabidopsis thaliana. KFBCHS physically interacts with CHS and specifically mediates its ubiquitination and degradation. KFBCHS
exhibits developmental expression patterns in Arabidopsis leaves, stems, and siliques and strongly responds to the dark-to-light (or the light-to-dark) switch, the blue, red, and far-red light signals, and UV-B irradiation. Alteration of KFBCHS
expression negatively correlates to the cellular concentration of CHS and the production of flavonoids. Our study suggests that KFBCHS serves as a crucial negative regulator, via mediating CHS degradation, coordinately controlling flavonoid biosynthesis in response to the developmental cues and environmental stimuli.
CO2 methanation over supported nickel catalysts attracts an increasing attention. However, the mechanism with it is still in debate. It is confirmed here that the structure of Ni/TiO2 catalyst has a ...significant effect on CO2 methanation. The catalyst with Ni (111) as the principal exposing facet shows higher activity with higher methane selectivity. The maximum activity for CO2 methanation is obtained at 350 °C with a CO2 conversion of 73.2% and a CO2 conversion rate of 1.56 molCO2gcat−1h−1 at a high GHSV of 60,000 h−1. This rate is higher than those reported CO2 conversion rates in the literature. According to the FTIR analysis, CO2 methanation over catalyst with Ni (111) as the principal exposing facet follows the mechanism via CO intermediate, while the catalyst with multi-facets takes the pathway of the direct hydrogenation of formate, with which nickel is only functional for hydrogen dissociation.
•CO2 methanation over Ni/TiO2 is a structure sensitive reaction.•Ni/TiO2 with Ni (111) follows the mechanism with CO as the intermediate.•Ni/TiO2 with multi-facets follows the mechanism via formate hydrogenation.•Ni/TiO2 with Ni (111) shows higher conversion with improved yield of methane.•Ni/TiO2 with Ni (111) shows enhanced low temperature activity.
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