Porous nonprecious metal-based nanomaterials have gained considerable attention in heterogeneous catalysis owing to their low price, high specific surface area, efficient mass/electron transfer, ...tunable pore structure, and unique physicochemical properties. Controlling the phase and compositions of these porous nonprecious metal-based materials is critical to their applications. Porous nonprecious transition-metal borides (TMBs), typical metal–metalloid alloys, have recently received much interest because of their optimized electronic structure, adjustable crystal phase, and abundant active site. The controlled tuning of the porous structure of TMBs, exploring the relationship between the structure and performance, and understanding the function of B are essential for developing catalysts with excellent performance; however, these factors have rarely been reviewed. Herein, a detailed summary of the synthesis methods of porous TMBs is provided by precisely defining their shape, composition, and pore size/structure. Incorporating B into metals can significantly alter their performance due to the unique metalloid properties of B. Further, we focus on the key roles of B in porous TMBs for related heterogeneous catalytic applications, including phase control, regulated electronic structure, optimized adsorption of reaction intermediates, and enhanced charge transfer and stability. Finally, we outline the shortcomings, challenges, and possible development of porous TMBs, which need to be further explored to increase TMBs’ contribution to heterogeneous catalyst applications and beyond.
Abstract
Amyloid precursor protein (APP) family members are involved in essential neuronal development including neurite outgrowth, neuronal migration and maturation of synapse and neuromuscular ...junction. Among the APP gene family members, amyloid precursor-like protein 1 (APLP1) is selectively expressed in neurons and has specialized functions during synaptogenesis. Although a potential role for APLP1 in neuronal evolution has been indicated, its precise evolutionary and functional contributions are unknown. This study shows the molecular evolution of the vertebrate APP family based on phylogenetic analysis, while contrasting the evolutionary differences within the APP family. Phylogenetic analysis showed 15 times higher substitution rate that is driven by positive selection at the stem branch of the mammalian APLP1, resulting in dissimilar protein sequences compared to APP/APLP2. Docking simulation identified one positively selected site in APLP1 that alters the heparin-binding site, which could affect its function, and dimerization rate. Furthermore, the evolutionary rate covariation between the mammalian APP family and synaptic adhesion molecules (SAMs) was confirmed, indicating that only APLP1 has evolved to gain synaptic adhesion property. Overall, our results suggest that the enhanced synaptogenesis property of APLP1 as one of the SAMs may have played a role in mammalian brain evolution.
The mechanical motion of materials has been increasingly explored in terms of bending and expansion/contraction. However, the locomotion of materials has been limited. Here, we report walking and ...rolling locomotion of chiral azobenzene crystals, induced thermally by a reversible single-crystal-to-single-crystal phase transition. Long plate-like crystals with thickness gradient in the longitudinal direction walk slowly, like an inchworm, by repeated bending and straightening under heating and cooling cycles near the transition temperature. Furthermore, thinner, longer plate-like crystals with width gradient roll much faster by tilted bending and then flipping under only one process of heating or cooling. The length of the crystal is shortened above the transition temperature, which induces bending due to the temperature gradient to the thickness direction. The bending motion is necessarily converted to the walking and rolling locomotion due to the unsymmetrical shape of the crystal. This finding of the crystal locomotion can lead to a field of crystal robotics.
Multimetallic alloys (MMAs) with various compositions enrich the materials library with increasing diversity and have received much attention in catalysis applications. However, precisely shaping ...MMAs in mesoporous nanostructures and mapping the distributions of multiple elements remain big challenge due to the different reduction kinetics of various metal precursors and the complexity of crystal growth. Here we design a one-pot wet-chemical reduction approach to synthesize core-shell motif PtPdRhRuCu mesoporous nanospheres (PtPdRhRuCu MMNs) using a diblock copolymer as the soft template. The PtPdRhRuCu MMNs feature adjustable compositions and exposed porous structures rich in highly entropic alloy sites. The formation processes of the mesoporous structures and the reduction and growth kinetics of different metal precursors of PtPdRhRuCu MMNs are revealed. The PtPdRhRuCu MMNs exhibit robust electrocatalytic hydrogen evolution reaction (HER) activities and low overpotentials of 10, 13, and 28 mV at a current density of 10 mA cm
in alkaline (1.0 M KOH), acidic (0.5 M H
SO
), and neutral (1.0 M phosphate buffer solution (PBS)) electrolytes, respectively. The accelerated kinetics of the HER in PtPdRhRuCu MMNs are derived from multiple compositions with synergistic interactions among various metal sites and mesoporous structures with excellent mass/electron transportation characteristics.
Abstract
Many single crystals have been developed and commercialized for optical isolators. However, optical isolator materials have been limited to isotropic crystals or to the isotropic direction ...(optic axis) of anisotropic crystals. This study investigates the wavelength dependences of linear birefringence, linear dichroism, Faraday rotation and magnetic-circular dichroism in a single crystal rare-earth fluoride, namely CeF
3
. Measurements were made in the direction parallel and perpendicular to the optic axis under an applied magnetic field. The magnetic field was generated by Nd-Fe-B magnets installed in the generalized-high accuracy universal polarimeter (G-HAUP). The first application of G-HAUP to a magneto-optical material is presented. In the CeF
3
crystal, the Verdet constants along directions parallel and perpendicular to the optic axis were positive over the measured wavelength region (300–680 nm), and their magnitudes were nearly equal. The success in the accurate measurement on Faraday rotation along anisotropic directions has opened the way to study on optical isolators along the direction other than optic axis.
This article reviews recent fabrication methods for surface‐enhanced Raman spectroscopy (SERS) substrates with a focus on advanced nanoarchitecture based on noble metals with special nanospaces ...(round tips, gaps, and porous spaces), nanolayered 2D materials, including hybridization with metallic nanostructures (NSs), and the contemporary repertoire of nanoarchitecturing with organic molecules. The use of SERS for multidisciplinary applications has been extensively investigated because the considerably enhanced signal intensity enables the detection of a very small number of molecules with molecular fingerprints. Nanoarchitecture strategies for the design of new NSs play a vital role in developing SERS substrates. In this review, recent achievements with respect to the special morphology of metallic NSs are discussed, and future directions are outlined for the development of available NSs with reproducible preparation and well‐controlled nanoarchitecture. Nanolayered 2D materials are proposed for SERS applications as an alternative to the noble metals. The modern solutions to existing limitations for their applications are described together with the state‐of‐the‐art in bio/environmental SERS sensing using 2D materials‐based composites. To complement the existing toolbox of plasmonic inorganic NSs, hybridization with organic molecules is proposed to improve the stability of NSs and selectivity of SERS sensing by hybridizing with small or large organic molecules.
A summary of advances in developing surface‐enhanced Raman spectroscopy (SERS)‐active substrates via fabrication methods of nanostructured metals and 2D materials is provided. Approaches for controlling metal tips/gaps/pores including advantages and disadvantages are discussed. Moreover, recent advances and challenges of novel 2D‐layered SERS‐active substrates are presented. Functionalization strategies for SERS surfaces include use of small or large molecules to complement the preparation procedures.
Mechanically responsive materials have been investigated extensively over the past two decades. Diversification of actuation modes is essential for the practical application of mechanical materials. ...Polymorphic crystals with different crystal structures composed of the same compound can exhibit distinct mechanical motions. Here, we focused on two polymorphs of a salicylideneaniline derivative with a 4-fluoro substituent in enol form, 1α and 1β, and investigated their different photomechanical behaviors. Under ultraviolet (UV) light irradiation, the thin plate-like 1α crystal bent away gradually and strongly from the light source, with some twist caused by enol–keto photoisomerization. In contrast, the thin, needle-like 1β crystal did not bend by photoisomerization; however, the thick 1β crystal bent away quickly from the light source because of the photothermal effect, ultimately achieving 500 Hz high-speed bending under pulsed UV laser irradiation. Moreover, the thick plate-like 1α crystal exhibited two-step motion: fast bending forward by the photothermal effect and then slow bending away by photoisomerization. We succeeded in creating four motions using two polymorphic crystals and two distinct mechanisms, thereby providing a novel approach to diversify the mechanical motions of molecular crystals and expanding the potential and versatility of molecular crystals as actuation materials.
Mammalian cells have been used in various research fields. More recently, cultured cells have been used as the cell source of “cultured meat.” Cell cultivation requires media containing nutrients, of ...which glucose and amino acids are the essential ones. These nutrients are generally derived from grains or heterotrophic microorganisms, which also require various nutrients derived from grains. Grain culture, in turn, requires many chemical fertilizers and agrochemicals, which can cause greenhouse gas emission and environmental contamination. Furthermore, grain production is greatly influenced by environmental changes. In contrast, microalgae efficiently synthesize various nutrients using solar energy, water, and inorganic substances, which are widely used in the energy sector. In this study, we aimed to apply nutrients extracted from microalgae in the culture media for mammalian cell cultivation. Glucose was efficiently extracted from Chlorococcum littorale or Arthrospira platensis using sulfuric acid, whereas 18 of the 20 proteinogenic amino acids were efficiently extracted from Chlorella vulgaris using hydrochloric acid. We further investigated whether nutrients present in the algal extracts could be used in mammalian cell cultivation. Although almost all C2C12 mouse myoblasts died during cultivation in a glucose‐ and amino acid‐free medium, the cell death was rescued by adding algal extract(s) into the nutrient‐deficient media. This indicates that nutrients present in algal extracts can be used for mammalian cell cultivation. This study is the first step toward the establishment of a new cell culture system that can reduce environmental loads and remain unaffected by the impact of environmental changes.
Cerebral organoids are three-dimensional in vitro cultured brains that mimic the function and structure of the human brain. One of the major challenges for cerebral organoids is the lack of ...functional vasculature. Without perfusable vessels, oxygen and nutrient supplies may be insufficient for long-term culture, hindering the investigation of the neurovascular interactions. Recently, several strategies for the vascularization of human cerebral organoids have been reported. However, the generalizable trends and variability among different strategies are unclear due to the lack of a comprehensive characterization and comparison of these vascularization strategies. In this study, we aimed to explore the effect of different vascularization strategies on the nervous system and vasculature in human cerebral organoids. We integrated single-cell RNA sequencing data of multiple vascularized and vascular organoids and fetal brains from publicly available datasets and assessed the protocol-dependent and culture-day-dependent effects on the cell composition and transcriptomic profiles in neuronal and vascular cells. We revealed the similarities and uniqueness of multiple vascularization strategies and demonstrated the transcriptomic effects of vascular induction on neuronal and mesodermal-like cell populations. Moreover, our data suggested that the interaction between neurons and mesodermal-like cell populations is important for the cerebrovascular-specific profile of endothelial-like cells. This study highlights the current challenges to vascularization strategies in human cerebral organoids and offers a benchmark for the future fabrication of vascularized organoids.
Photomechanically responsive materials are promising candidates for future smart actuator applications. The photo-responsive behaviors originate from the photoisomerization of photochromic molecules. ...A typical photochromic compound, azobenzene, has been studied extensively in the solution state and has played a crucial role in the photomechanical behaviors of materials such as polymers and gels, via chemical bridging with their matrix. In contrast to polymers and gels, the photomechanical attributes of molecular crystals have not progressed to the same degree, due to their rigidity and fragility. However, the past decade has witnessed an increasing number of reports of the photomechanical motion of molecular crystals, including azobenzene crystals. This paper reviews the current state-of-the-art of mechanically responsive azobenzene crystals, including the history, crystal design strategy, and future promising applications.
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