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.
Next-generation sequencing (NGS) has been widely adopted for clinical HLA typing and advanced immunogenetics researches. Current methodologies still face challenges in resolving cis–trans ambiguity ...involving distant variant positions, and the turnaround time is affected by testing volume and batching. Nanopore sequencing may become a promising addition to the existing options for HLA typing. The technology delivered by the MinION sequencer of Oxford Nanopore Technologies (ONT) can record the ionic current changes during the translocation of DNA/RNA strands through transmembrane pores and translate the signals to sequence reads. It features simple and flexible library preparations, long sequencing reads, portable and affordable sequencing devices, and rapid, real-time sequencing. However, the error rate of the sequencing reads is high and remains a hurdle for its broad application. This review article will provide a brief overview of this technology and then focus on the opportunities and challenges of using nanopore sequencing for high-resolution HLA typing and immunogenetics research.
The CRISPR-Cas9 genome-editing system is a part of the adaptive immune system in archaea and bacteria to defend against invasive nucleic acids from phages and plasmids. The single guide RNA (sgRNA) ...of the system recognizes its target sequence in the genome, and the Cas9 nuclease of the system acts as a pair of scissors to cleave the double strands of DNA. Since its discovery, CRISPR-Cas9 has become the most robust platform for genome engineering in eukaryotic cells. Recently, the CRISPR-Cas9 system has triggered enormous interest in therapeutic applications. CRISPR-Cas9 can be applied to correct disease-causing gene mutations or engineer T cells for cancer immunotherapy. The first clinical trial using the CRISPR-Cas9 technology was conducted in 2016. Despite the great promise of the CRISPR-Cas9 technology, several challenges remain to be tackled before its successful applications for human patients. The greatest challenge is the safe and efficient delivery of the CRISPR-Cas9 genome-editing system to target cells in human body. In this review, we will introduce the molecular mechanism and different strategies to edit genes using the CRISPR-Cas9 system. We will then highlight the current systems that have been developed to deliver CRISPR-Cas9 in vitro and in vivo for various therapeutic purposes.
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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.
Defects are now recognized to be a useful tool in tailoring the properties of metal-organic frameworks (MOFs). The introduction of missing linker and cluster defects into MOFs provides additional ...active sites, optimizes the acidity/basicity, improves the conductivity, tailors mechanical responses and creates more pore space to enhance diffusion and mass transfer in MOFs. Structural defects in MOFs have been demonstrated to be beneficial in areas such as catalysis, decontamination, bio-applications, adsorption, separation, energy storage, energy conversion, electronics, magnetics, optical functional materials and others. Defective MOFs are also excellent model materials for the fundamental study of defect chemistry. In this review, we provide a general overview of the commonly available methods that are feasible for the creation and characterization of structural defects in MOF materials. Additionally, recent studies on various applications of defective MOFs are highlighted, aiming to provide new insights into the design and introduction of structural defects to synthesize MOF materials with high performance and to promote the wide application of defective MOFs in various fields. Challenges and future perspectives on defect engineering of MOFs are also addressed.
An overview of important recent advances on synthesis, characterization and application of defective metal-organic frameworks is provided.
The hydroisomerization of n -alkanes over bifunctional catalysts has played an increasingly important role in the modern petroleum industry due to its evident effects on the enhancement of the ...quality of fossil fuels. However, the preparation of bifunctional catalysts with excellent catalytic performance remains a significant challenge because of the complicated synergistic effects between the metal sites and Brønsted acid sites and the limited diffusion of alkene intermediates in the acid support. To overcome this challenge, the improvement of the metal–acid balance and the synthesis of hierarchical acid supports have become two commonly employed strategies. On the one hand, the favourable metal–acid balance is beneficial for the ideal consecutive hydroisomerization mechanism, which can be achieved by choosing the appropriate ratio of metal sites to Brønsted acid sites, controlling the nanoscale distance between two active sites, reducing the acidity and function of Brønsted acid sites, enhancing the function of metal sites and lowering the cost of preparation. On the other hand, via the “top down” (like desiliconization post-treatment) or “bottom up” (like templating methods) methods, the prepared hierarchical acid supports have more pore mouths or evidently reduced diffusion length. As a result, the alkene intermediates can either undergo isomerization at pore mouth instead of diffusing in the microporous channels or diffuse out fast from the short microporous channels, so that the diffusion limitation of alkene intermediates can be overcome and their cracking is inhibited. In this review, we summarize the recent advances in the developments of bifunctional catalysts for n -alkane hydroisomerization. The novel synthesis methods of the bifunctional catalysts are introduced, as well as the catalytic behaviours and the reaction mechanisms over catalysts. The effects of the metal–acid balance and the textural property on the catalytic performances are also discussed. The summarized studies reveal excellent potential for the design and preparation of novel bifunctional catalysts with excellent catalytic performances for n -alkane hydroisomerization.
Laser absorption spectroscopy (LAS) has been rapidly developed and widely applied to combustion diagnosis in recent decades. As a cost-effective tool for measuring multiple combustion parameters, LAS ...provides unique properties in terms of accuracy and sensitivity for understanding the reactions and kinetics in reactive flows. Line-of-sight and tomographic LAS techniques have stimulated numerous applications and been proved to be robust for in situ combustion diagnosis in uniform and non-uniform combustion fields, respectively. This review highlights the breakthroughs in the evolution of LAS techniques from the viewpoints of key principles, sensors and instrumentations developed for combustion diagnosis, with particular emphasis on a series of spatially-resolved LAS techniques with their recent applications on obtaining high-fidelity measurement results with minimal intrusion to the practical combustors. Along the way, we note some challenges and requirements for further development of the LAS-based combustion diagnosis.
• 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.
This paper presents an experimental study of the phase change heat transfer inside a cylindrical latent heat energy storage system (LHESS), designed with a central finned copper pipe running the ...length of the cylindrical container, during charging and discharging operations. Longitudinal fins were added to the copper pipe to enhance the overall heat transfer rates during the phase change processes; fins with two orientations, straight fins and angled fins, are used. The phase change material (PCM) used is dodecanoic acid. The experimental work concentrates on studying the heat transfer mechanism during melting and solidification of the PCM, impacts of the heat transfer fluid (HTF) inlet temperature and HTF flow rates. Moreover, heat transfer enhancement effectiveness of straight fins and angles fins configurations is compared. It is observed that conduction is the dominant heat transfer mechanism during the initial stage of charging, and natural convection dominates once enough liquid PCM is present inside the system. Conduction dominates during the entire solidification process. Complete melting time is strongly affected by the HTF inlet temperature but very slightly by the HTF flow rates.
•Experimental study of the phase change heat transfer inside a cylindrical latent heat energy storage system.•Both charging (melting) and discharging (solidification) experiments were performed.•During charging, natural convection is the dominant mode of heat transfer once enough liquid melt is present.•During discharging, conduction is the only mode of heat transfer, requiring the design and addition of fins.•The heat transfer fluid inlet temperature greatly affects the overall charging and discharging process within the system.
In this paper, we investigate the Pontryagin trace anomaly for chiral fermions in a general curved background using Pauli-Villars regularization. We use both Feynman diagram method and Fujikawa's ...method to calculate the parity-odd contribution (Pontryagin term). Our result indicates that the trace anomaly of energy-momentum tensor for chiral fermions has Pontryagin term P=i1536π2ϵνσκλRρμνσRρμκλ which agrees with the work of Bonora et al. 1.
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