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Abstract The ever‐increasing importance of critical metals (CMs) in modern society underscores their resource security and circularity. Waste‐printed circuit boards (WPCBs) are particularly attractive reservoirs of CMs due to their gamut CM embedding and ubiquitous presence. However, the recovery of most CMs is out of reach from current metal‐centric recycling industries, resulting in a flood loss of refined CMs. Here, 41 types of such spent CMs are identified. To deliver a higher level of CM sustainability, this work provides an insightful overview of paradigm‐shifting pathways for CM recovery from WPCBs that have been developed in recent years. As a crucial starting entropy‐decreasing step, various strategies of metal enrichment are compared, and the deployment of artificial intelligence (AI) and hyperspectral sensing is highlighted. Then, tailored metal recycling schemes are presented for the platinum group, rare earth, and refractory metals, with emphasis on greener metallurgical methods contributing to transforming CMs into marketable products. In addition, due to the vital nexus of CMs between the environment and energy sectors, the upcycling of CMs into electro‐/photo‐chemical catalysts for green fuel synthesis is proposed to extend the recycling chain. Finally, the challenges and outlook on this all‐round upgrading of WPCB recycling are outlined.

Abstract Thermoelectric materials are highly promising for waste heat harvesting. Although thermoelectric materials research has expanded over the years, bismuth telluride‐based alloys are still the best for near‐room‐temperature applications. In this work, a ≈38% enhancement of the average ZT (300−473 K) to 1.21 is achieved by mixing Bi0.4Sb1.6Te3 with an emerging thermoelectric material Sb2Si2Te6, which is significantly higher than that of most BiySb2−yTe3‐based composites. This enhancement is facilitated by the unique interface region between the Bi0.4Sb1.6Te3 matrix and Sb2Si2Te6‐based precipitates with an orderly atomic arrangement, which promotes the transport of charge carriers with minimal scattering, overcoming a common factor that is limiting ZT enhancement in such composites. At the same time, high‐density dislocations in the same region can effectively scatter the phonons, decoupling the electron‐phonon transport. This results in a ≈56% enhancement of the thermoelectric quality factor at 373 K, from 0.41 for the pristine sample to 0.64 for the composite sample. A single‐leg device is fabricated with a high efficiency of 5.4% at ΔT = 164 K further demonstrating the efficacy of the Sb2Si2Te6 compositing strategy and the importance of the precipitate‐matrix interface microstructure in improving the performance of materials for relatively low‐temperature applications.

Abstract Recent progress in two-dimensional ferroelectrics greatly expands the versatility and tunability in van der Waals heterostructure based electronics. However, the switching endurance issue that widely plagues conventional ferroelectrics in practical applications is hitherto unexplored for van der Waals layered ferroelectrics. Herein, we report the observation of unusual polarization fatigue behaviors in van der Waals layered CuInP2S6, which also possesses finite ionic conductivity at room temperature. The strong intertwinement of the short-range polarization switching and long-range ionic movement in conjunction with the van der Waals layered structure gives rise to unique morphological and polarization evolutions under repetitive electric cycles. With the help of concerted chemical, structural, lattice vibrational and dielectric analyses, we unravel the critical role of the synergy of ionic migration and surface oxidation on the anomalous polarization enhancement and the eventual polarization degradation. This work provides a general insight into the polarization fatigue characteristics in ionically-active van der Waals ferroelectrics and delivers potential solutions for the realization of fatigue-free capacitors.

The high proportion of distributed photovoltaic (DPV) access has changed the traditional distribution network structure and operation mode, posing a huge threat to the stable operation and economy of the distribution network. Aiming at a reasonable access capacity of DPV in the distribution network, this paper proposes an economic access capacity evaluation method for DPV in the distribution network considering proper PV power curtailment. Firstly, a method for generating typical joint light intensity and load power operation scenarios based on an improved K-means clustering algorithm is proposed, which provides comprehensive scenario support for the evaluation. Secondly, based on active and reactive power regulation, this paper proposes a DPV access capacity enhancement method to improve the DPV access capacity. Thirdly, considering proper PV power curtailment, an evaluation model of DPV economic access capacity in the distribution network is established to solve the maximum DPV economic access capacity in the distribution network. And aiming at the nonlinear problem in the model, the second-order cone relaxation method is employed to transform the model into the second-order cone programming model, so as to solve the objective function conveniently and efficiently. Finally, based on the improved IEEE 33-node distribution network analysis, the results show that the proposed method can be more comprehensive and effective in evaluating the DPV economic access capacity in the distribution network, and proper PV power curtailment can significantly increase the DPV economic access capacity in the distribution network.

Abstract Doping usually reduces lattice thermal conductivity because of enhanced phonon-impurity scattering. Here, we report unexpected doping effects on the lattice thermal conductivity of quasi-one-dimensional (quasi-1D) van der Waals (vdW) TiS3 nanoribbons. As the nanoribbon thickness reduces from ~80 to ~19 nm, the concentration of oxygen atoms has a monotonic increase along with a 7.4-fold enhancement in the thermal conductivity at room temperature. Through material characterizations and atomistic modellings, we find oxygen atoms diffuse more readily into thinner nanoribbons and more sulfur atoms are substituted. The doped oxygen atoms induce significant lattice contraction and coupling strength enhancement along the molecular chain direction while have little effect on vdW interactions, different from that doping atoms induce potential and structural distortions along all three-dimensional directions in 3D materials. With the enhancement of coupling strength, Young’s modulus is enhanced while phonon-impurity scattering strength is suppressed, significantly improving the phonon thermal transport.

Abstract The utilization of chelation reaction between metals and tannins is a common tanning method in leather chemistry. Herein, a novel combination tanning mechanism inspired environmentally benign catalyst (CMBT-Fe0) was synthesized by immobilizing Fe nanoparticles onto bayberry tannin (BT) grafted chitosan microfibers (CM). The obtained catalyst featured a well-defined microfibrous structure, on which Fe0 nanoparticles were highly dispersed to exhibit exceptional catalytic activity for the degradation of tetracycline (TC). The catalytic activity of CMBT-Fe0 was 1.72 times higher than that of the commercial Fe0 nanoparticles without immobilization, with 95.03% of TC degraded within 90.0 min. The CMBT-Fe0 catalysts were recycled 6 times, with the removal rate of TC maintained at 82.56%. Furthermore, a possible mechanism responsible for the catalytic removal of TC was provided by analyzing the catalytic degradation products via liquid chromatography-mass spectrometry. Therefore, our investigation successfully developed efficient catalysts to address the concerned environmental issue of antibiotic pollution. Graphical Abstract

Decades of studies on thermoelectric materials have enabled the design of high‐performance materials based on basic materials properties, such as bandgap engineering. In general, bandgap energies correspond to the temperature at which the peak thermoelectric performance occurs. For instance, CuGaTe2 with a relatively wide bandgap of 1.2 eV has its peak zT > 1 at > 900 K. On the other hand, the zT is usually very low (

The traditional method of urea production is a carbon-emitting, energy-intensive technology that contradicts the concept of carbon neutrality. Fortunately, the use of renewable energy in electrochemical synthesis has shown great potential for producing high-value nitrogen products, making electrocatalytic urea production a promising and sustainable approach. However, the low yield and Faraday efficiency, as well as the unclear mechanism of C-N bond formation, limit its large-scale industrial development. Researchers are seeking higher-performance electrocatalysts. This article discusses in detail the latest progress in the electrochemical synthesis of urea using carbon dioxide and various nitrogen sources, including catalyst design and preparation, as well as the mechanism of C-N coupling reactions. It also provides comprehensive analysis on the challenges and prospects facing urea electro-synthesis. The development of targeted and efficient new catalysts for urea synthesis is anticipated to bring about more sustainable and cost-effective production methods.

Abstract Developing sustainable and clean energy‐conversion techniques is one of the strategies to simultaneously meet the global energy demand, save fossil fuels and protect the environment, in which nanocatalysts with high activity, selectivity and durability are of great importance. Intermetallic nanocrystals, featuring their ordered atomic arrangements and predictable electronic structures, have been recognized as a type of active and durable catalysts in energy‐related applications. In this minireview, the very recent progress in the syntheses and electrocatalytic applications of noble metal‐based intermetallic nanocrystals is summarized. Various synthetic strategies, including the conventional thermal annealing approach and its diverse modifications, as well as the wet‐chemical synthesis, for the construction of binary, ternary and high‐entropy intermetallic nanocrystals have been discussed with representative examples, highlighting their strengths and limitations. Then, their electrocatalytic applications toward oxygen reduction reaction, small molecule oxidation reactions, hydrogen evolution reaction, CO2/CO reduction reactions, and nitrogen reduction reaction are discussed, with the emphasis on how the ordered intermetallic structures contribute to the enhanced performance. We conclude the minireview by addressing the current challenges and opportunities of intermetallic nanocrystals in terms of syntheses and electrocatalytic applications.

Abstract With the excessive consumption of nonrenewable resources, the exploration of effective and durable materials is highly sought after in the field of sustainable energy conversion and storage system. In this aspect, metal‐organic frameworks (MOFs) are a new class of crystalline porous organic‐inorganic hybrid materials. MOFs have recently been gaining traction in energy‐related fields. Owing to the coordination flexibility and multiple accessible oxidation states of vanadium ions or clusters, vanadium‐MOFs (V‐MOFs) possess unique structural characteristics and satisfactory electrochemical properties. Furthermore, V‐MOFs‐derived materials also exhibit superior electrical conductivity and stability when used as electrocatalysts and electrode materials. This review summarizes the research progress of V‐MOFs (inclusive of pristine V‐MOFs, V/M‐MOFs, and POV‐based MOFs) and their derivatives (vanadium oxides, carbon‐coated vanadium oxide, vanadium phosphate, vanadate, and other vanadium doped nanomaterials) in electrochemical energy conversion (water splitting, oxygen reduction reaction) and energy storage (supercapacitor, rechargeable battery). Future possibilities and challenges for V‐MOFs and their derivatives in terms of design and synthesis are discussed. Lastly, their applications in energy‐related fields are also highlighted.

Abstract Phase change materials (PCMs) are promising thermal energy storage materials due to their high specific latent heat. Conventional PCMs typically exploit the solid–liquid (s–l) transition. However, leakage and leaching are common issues for solid–liquid PCMs, which have to be addressed before usage in practical applications. In contrast, solid–solid (s–s) PCMs would naturally overcome these issues due to their inherent form stability and homogeneity. In this study, we report a new type of s–s PCM based on chemically linked polyethylene glycol (PEG, the PCM portion) with polylactic acid (PLA, the support portion) in the form of a block co‐polymer. Solid‐solid latent heat of up to 56 J/g could be achieved, with melting points of between 44 °C and 55 °C. For comparison, PEG was physically mixed into a PLA matrix to form a PEG:PLA composite. However, the composite material saw leakage of up to 9% upon heating, with a corresponding loss in thermal storage capacity. In contrast, the mPEG/PLA block co‐polymers were found to be completely homogeneous and thermally stable even when heated above its phase transition temperature, with no observable leakage, demonstrating the superiority of chemical linking strategies in ensuring form stability.

Li metal has been recognized as the most promising anode materials for next-generation high-energy-density batteries, however, the inherent issues of dendrite growth and huge volume fluctuations upon Li plating/stripping normally result in fast capacity fading and safety concerns. Functionalized Cu current collectors have so far exhibited significant regulatory effects on stabilizing Li metal anodes (LMAs), and hold a great practical potential owing to their easy fabrication, low-cost and good compatibility with the existing battery technology. In this review, a comprehensive overview of Cu-based current collectors, including planar modified Cu foil, 3D architectured Cu foil and nanostructured 3D Cu substrates, for Li metal batteries is provided. Particularly, the design principles and strategies of functionalized Cu current collectors associated with their functionalities in optimizing Li plating/stripping behaviors are discussed. Finally, the critical issues where there is incomplete understanding and the future research directions of Cu current collectors in practical LMAs are also prospected. This review may shed light on the critical understanding of current collector engineering for high-energy-density Li metal batteries.

Abstract High‐entropy materials, composed of five or more elements in near‐equiatomic percentage, have been attracting tremendous interests due to their advantageous properties in a variety of applications. Recently, electrocatalysis on high‐entropy alloys (HEAs) and high‐entropy compounds (HECs) has emerged as a new and promising material owing to the tailored composition and the disordered configuration of HEAs and HECs. Though extensive efforts have been devoted to investigating the catalytic nature of HEAs and HECs, the details related to the active sites and intrinsic activity of such catalysts still remain uncertain due to the complexity of the multicomponent systems. In this review, the recent progress of HEAs and HECs is systematically reviewed in terms of their synthetic strategies and electrocatalytic applications. Importantly, the computationally assisted methods (e.g., density functional theory [DFT]) are also presented to discover and design the optimum HEA‐ and HEC‐based catalysts. Subsequently, the applications of HEAs and HECs in electrocatalytic energy conversion reactions will be discussed, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, methanol oxidation reaction, and ethanol oxidation reaction (EOR). Moreover, the prospects and future opportunities for this research field are cautiously discussed. A series of upcoming challenges and questions are thoroughly proposed from the experimental and theoretical aspects as well as other future applications in electrocatalysis.

Lillianite materials usually have low thermoelectric efficiency due to the inherently inferior electrical properties. Here, the authors evaluate thermoelectric performances in Pb7Bi4Se13 based lillianites enabled by convergence of nested conduction bands.

Abstract Biological applications of nanomaterials as delivery carriers have been embedded in traditional biomedical research for decades. Despite lagging behind, recent significant breakthroughs in the use of nanocarriers as tools for plant biotechnology have created great interest. In this Perspective, we review the outstanding recent works in nanocarrier‐mediated plant transformation and its agricultural applications. We analyze the chemical and physical properties of nanocarriers determining their uptake efficiency and transport throughout the plant body.

Phase Change Materials (PCM) are efficient materials for thermal management and energy storage due to its high latent heat and recyclability. Many strategies have been employed to form stabilize PCMs through their phase transition; however these materials are almost invariably rigid. Herein a novel flexible form-stable PCM composite was successfully prepared by physical mixing and low temperature curing. They were well characterized in terms of various techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), mechanical and leakage test, etc. A leakage test showed that the composite with 50% octadecane loading was form-stable with only 2.44% leakage. From the differential scanning calorimetry (DSC) results, the octadecane/silicone (Oct/Si) composite was found to possess a latent heat of 103.8 J/g, and an upshift in phase transition temperature was also observed from octadecane's melting point of 30.3 °C to between 34.4 and 37.8 °C, probably due to thermal insulation or microencapsulation by the silicone matrix. Thermogravimetric analysis (TGA) data supported its good thermal stability within this temperature range and mechanical testing of the composites further confirmed its flexibility and durability as evidenced by the Young's Modulus at 388.92 kPa and elongation at 341.42%, making Oct/Si composites useful for application in areas of temperature regulation, cooling, energy harvesting and wearable devices.

Abstract Presented are the synthesis, characterizations, and reactive surface modification (RSM) of a novel nine atomic layered V4C3T x MXene. With the advantages of the multilayered V4C3T x MXene that can simultaneously support the RSM reaction and keep the inner skeleton stable, a series of amorphous Ni/Fe/V‐ternary oxide hydroxides thin layer can be successfully modified on the surface of the V4C3T x MXene (denoted as MOOH @V4C3T x, M = Ni, Fe, and V) without disrupting its original structure. Attributed to the in situ reconstruction of highly active oxide hydroxide layer, the nanohybrids exhibited an enhanced oxygen evolution reaction (OER) activity and excellent long‐time stability over 70 hours. In particular, a current density of 10 mA cm−2 can be reached by the nanohybrid with the optimized Ni/Fe ratio at an overpotential (η) as low as 275.2 mV, which is comparable to most of the state‐of‐the‐art OER catalysts and better than other MXene‐based derivatives. Demonstrated by the tunable physicochemical properties and excellent structural stability of these nanohybrids, we may envision the promising role of the M4X3‐based MXenes as substrates for a wide range of energy conversion and storage materials.

Symbolic regression holds big promise for guiding materials design, yet its application in materials science is still limited. Here the authors use symbolic regression to introduce an activity descriptor predicting new oxide perovskites with improved oxygen evolution activity as corroborated by experimental validation.

Abstract Owing to the large surface area and adjustable surface properties, the two‐dimensional (2D) MXenes have revealed the great potential in constructing hybrid materials and for Na‐ion storage (SIS). In particular, the facilitated Na‐ion adsorption, intercalation, and migration on MXenes can be achieved by surface modification. Herein, a new surface modification strategy on MXenes, namely, the reactive surface modification (RSM), is focused and illustrated, while the recent advances in the research of SIS performance based on MXenes and their derivatives obtained from the RSM process are briefly summarized as well. In the second section, the intrinsic surface chemistries of MXenes and their surface‐related physicochemical properties are first summarized. Meanwhile, the close relationship between the surface characters and the Na‐ion adsorption, intercalation, and migration on MXenes is emphasized. Following the SIS properties of MXenes, the surface‐induced SIS property variations, and the SIS performance of RSM MXene‐based hybrids are discussed progressively. Finally, the existing challenges and prospects on the RSM MXene‐based hybrids for SIS are proposed.

To move away from fossil fuels, the electrochemical reaction plays a critical role in renewable energy sources and devices. The anodic oxygen evolution reaction (OER) is always coupled with these reactions in devices but suffers from large energy barriers. Thus, it is important for developing efficient OER catalysts with low overpotential. On the other hand, there are large amounts of metals in electronic waste (E-waste), especially various transition metals that are promising alternatives for catalyzing OER. Hence, this work, which focuses on upcycling Class II BaTiO3 Multilayer Ceramic Capacitors, of which two trillion were produced in 2011 alone. We achieved this by first using a green solvent extraction method that combined the ionic liquid Aliquat® 336 and hydrochloride acid to recover a mixed solution of Ni, Fe and Cu cations, and then using such a solution to synthesize high potential catalysts NiFe hydroxide and NiCu hydroxide for OER. NiFe-hydroxide has been demonstrated to have faster OER kinetics than the NiCu-hydroxide and commercial c-RuO2. In addition, it showed promising results after the chronopotentiometry tests that outperform c-RuO2.

Abstract Due to the rapidly increasing demand for energy and environmental sustainability, stable and economical hydrogen production has received increasing attention in the past decades. In this regard, hydrogen production through photo- or electrocatalytic water splitting has continued to gain ever-growing interest. However, the existing catalysts are still unable to fulfill the demands of high-efficiency, low-cost, and sustainable hydrogen production. Layered metal trichalcogenidophosphate (MPQ3) is a newly developed two-dimensional material with tunable composition and electronic structure. Recently, MPQ3 has been considered a promising candidate for clean energy generation and related water splitting applications. In this minireview, we firstly introduce the structure and methods for the synthesis of MPQ3 materials. In the following sections, recent developments of MPQ3 materials for photo- and electrocatalytic water splitting are briefly summarized. The roles of MPQ3 materials in different reaction systems are also discussed. Finally, the challenges related to and prospects of MPQ3 materials are presented on the basis of the current developments.

Progress in renewable energy production has directed interest in advanced developments of energy storage systems. The all-vanadium redox flow battery (VRFB) is one of the attractive technologies for large scale energy storage due to its design versatility and scalability, longevity, good round-trip efficiencies, stable capacity and safety. Despite these advantages, the deployment of the vanadium battery has been limited due to vanadium and cell material costs, as well as supply issues. Improving stack power density can lower the cost per kW power output and therefore, intensive research and development is currently ongoing to improve cell performance by increasing electrode activity, reducing cell resistance, improving membrane selectivity and ionic conductivity, etc. In order to evaluate the cell performance arising from this intensive R&D, numerous physical, electrochemical and chemical techniques are employed, which are mostly carried out ex situ, particularly on cell characterizations. However, this approach is unable to provide in-depth insights into the changes within the cell during operation. Therefore, in situ diagnostic tools have been developed to acquire information relating to the design, operating parameters and cell materials during VRFB operation. This paper reviews in situ diagnostic tools used to realize an in-depth insight into the VRFBs. A systematic review of the previous research in the field is presented with the advantages and limitations of each technique being discussed, along with the recommendations to guide researchers to identify the most appropriate technique for specific investigations.

Abstract Presented are the theoretical calculation and experimental studies of a Ti3C2Tx MXene‐based nanohybrid with simultaneous Nb doping and surface transition metal alloy modification. Guided by the density functional theory calculation, the Nb doping can move up the Fermi energy level to the conduction band, thus enhancing the electronic conductivity. Meanwhile, the surface modification by Ni/Co alloy can moderate the surface M–H affinity, which will further enhance the hydrogen evolution reaction (HER) activity. A series of Ni/Co alloy attached on Nb‐doped Ti3C2Tx MXene nanohybrids (denoted as NiCo@NTM) are successfully prepared. As expected, the Ni0.9Co0.1@ NTM nanohybrids present an extraordinary HER activity in alkaline solution, which only needs an overpotential (η) of 43.4 mV to reach the current density of 10 mA cm−2 in 1 m KOH solution and shows good stability. The performance of the Ni0.9Co0.1@ NTM nanohybrids is comparable to the commercial 10% Pt/C electrode (34.4 mV@10 mA cm−2) and is better than most state‐of‐the‐art Pt‐free HER catalysts. Inspired by the facile synthesis process and chemical versatility of both MXene and transition metal alloys, the nanohybrids reported here are promising non‐noble metal electrocatalysts for water–alkali electrolysis.

Transition-metal-doped tungsten semicarbide nanosheets (M-doped W2C NSs, M=Fe, Co, and Ni) have been synthesized through carburization of the mixture of tungsten trioxide, polyvinylpyrrolidone, and metal dopant. The nanosheets grow directly on the W mesh and have the lateral dimension of several hundreds of nm to a few μm with a thickness of few tens nm. It is demonstrated that the M-doped W2C NSs exhibit superior electrocatalytic activity for hydrogen evolution reaction (HER). Impressively, the Ni-doped W2C NSs (2 at% Ni) with the optimized HER activity show extremely low onset overpotentials of 4, 9, and 19 mV and modest Tafel slopes of 39, 51, and 87 mV dec−1 in acidic (pH=0), neutral (pH=7.2), and basic (pH=14) solutions, respectively, which is close to the commercial Pt/C catalyst. Density functional theory (DFT) calculations also demonstrate that the Gibbs free energy for H adsorption of Ni-W2C is much closer to the optimal value ∆GH⁎ = -0.073 eV as compared to -0.16 eV of W2C. Furthermore, nearly 100% Faradaic efficiency and long-term stability are obtained in those environments. This realization of highly tolerant metal semicarbide catalyst performing on par with commercial Pt/C in all range of pH offers a key step towards industrially electrochemical water splitting.

Segmented cells enable real time visualization of the flow distribution in vanadium redox flow batteries by local current or voltage mapping. The lateral flow of current within thick porous electrodes, however, impairs the local resolution of the detected signals. In this study, the open circuit voltage immediately after the cessation of charge/discharge is used for the mapping of reactant conversion. This quantity is not hampered by lateral flow of current and can be conveniently transformed to the corresponding state of charge. The difference between theoretically calculated and experimentally determined conversion (change in the state of charge) across the electrode is used to determine local variations in conversion efficiency. The method is validated by systematic experiments using electrodes with different modifications, varying current densities and flow configurations. The procedure and the interpretation are simple and scalable to any size of flow cell.

We report a facile method to prepare a nanoarchitectured lithium manganate/graphene (LMO/G) hybrid as a positive electrode for Li-ion batteries. The Mn2O3/graphene hybrid is synthesized by exfoliation of graphene sheets and deposition of Mn2O3 in a one-step electrochemical process, which is followed by lithiation in a molten salt reaction. There are several advantages of using the LMO/G as cathodes in Li-ion batteries: (1) the LMO/G electrode shows high specific capacities at high gravimetric current densities with excellent cycling stability, e.g., 84 mAh·g−1 during the 500th cycle at a discharge current density of 5625 mA·g−1 (~38.01 C capacity rating) in the voltage window of 3–4.5 V; (2) the LMO/G hybrid can buffer the Jahn–Teller effect, which depicts excellent Li storage properties at high current densities within a wider voltage window of 2–4.5 V, e.g., 93 mAh·g−1 during the 300th cycle at a discharge current density of 5625 mA·g−1 (~38.01 C). The wider operation voltage window can lead to increased theoretical capacity, e.g., 148 mAh·g−1 between 3 and 4.5 V and 296 mAh·g−1 between 2 and 4.5 V; (3) more importantly, it is found that the attachment of LMO onto graphene can help to reduce the dissolution of Mn2+ into the electrolyte, as indicated by the inductively coupled plasma (ICP) measurements, and which is mainly attributed to the large specific surface area of the graphene sheets.

Peptidoglycan recognition proteins (PGRPs), which have been identified in most animals, are pattern recognition molecules that involve antimicrobial defense. Resulting from extraordinary expansion of innate immune genes, the amphioxus encodes many PGRPs of diverse functions. For instance, three isoforms of PGRP encoded by Branchiostoma belcheri tsingtauense, termed BbtPGRP1~3, are fused with a chitin binding domain (CBD) at the N-terminus. Here we report the 2.7 Å crystal structure of BbtPGRP3, revealing an overall structure of an N-terminal hevein-like CBD followed by a catalytic PGRP domain. Activity assays combined with site-directed mutagenesis indicated that the individual PGRP domain exhibits amidase activity towards both DAP-type and Lys-type peptidoglycans (PGNs), the former of which is favored. The N-terminal CBD not only has the chitin-binding activity, but also enables BbtPGRP3 to gain a five-fold increase of amidase activity towards the Lys-type PGNs, leading to a significantly broadened substrate spectrum. Together, we propose that modular evolution via domain shuffling combined with gene horizontal transfer makes BbtPGRP1~3 novel PGRPs of augmented catalytic activity and broad recognition spectrum.

Second generation sequencing has been widely used to sequence whole genomes. Though various paired-end sequencing methods have been developed to construct the long scaffold from contigs derived from shotgun sequencing, the classical paired-end sequencing of the Bacteria Artificial Chromosome (BAC) or fosmid libraries by the Sanger method still plays an important role in genome assembly. However, sequencing libraries with the Sanger method is expensive and time-consuming. Here we report a new strategy to sequence the paired-ends of genomic libraries with parallel pyrosequencing, using a Chinese amphioxus (Branchiostoma belcheri) BAC library as an example. In total, approximately 12,670 non-redundant paired-end sequences were generated. Mapping them to the primary scaffolds of Chinese amphioxus, we obtained 413 ultra-scaffolds from 1,182 primary scaffolds, and the N50 scaffold length was increased approximately 55 kb, which is about a 10% improvement. We provide a universal and cost-effective method for sequencing the ultra-long paired-ends of genomic libraries. This method can be very easily implemented in other second generation sequencing platforms.