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Reaction of blue crystalline solid trans-[CuCl2(4-Clpy)2] 1(4-Clpy = 4-chloropyridine) with anhydrous HCl gas yields yellow crystalline salt (4-ClpyH)2[CuCl4] 2with quantitative conversion. The reaction has been followed in situby synchrotron powder X-ray diffraction using a specially designed gas-handling rig and demonstrates that the initial product is a C-centred monoclinic form of (4-ClpyH)2[CuCl4] (phase II), which then converts in the solid state to a primitive monoclinic form (phase I). The conversion has been quantified at each stage by mixed-phase Rietveld refinement of the powder diffraction data. The two polymorphic forms exhibit different patterns of N–HCl(Cu) hydrogen bonding and C–ClCl(Cu) halogen bonding. Evidence from solution-phase crystallisations of 2suggests that phase II is a kinetic product and phase I is the thermodynamic product. The salt 2can also be prepared mechanochemically, by grinding for 2 min green-blue solid CuCl2·2H2O with white solid [4-ClpyH]Cl in a 1 : 2stoichiometric ratio. The product was identified by powder diffraction as phase I of compound 2in 97.5% yield, with the remaining material being compound 1. [ABSTRACT FROM AUTHOR]

Boron nitride nanotubes (BNNTs) are novel because of their wide band gap, superb mechanical properties, high thermal conductivity and robustness to oxidation. These features make BNNTs promising nanofillers that lead to the significant mechanical reinforcement and improvement of thermal conductivity of a composite. However, only in recent years, benefiting from the development of effective syntheses of BNNTs, have the follow-up chemical functionalization and composite studies of BNNTs been initiated. To achieve better solubility and processability of BNNTs, various methods have been developed to functionalize BNNTs via different interactions. Moreover, BNNT polymeric and ceramic composites have been fabricated and property improvements have indeed been documented. In this feature article, we summarize the recent progress in the chemistry and composite research of BNNTs. [ABSTRACT FROM AUTHOR]

In this paper, we introduce an entirely new solar absorber design-a multi-layer periodic stacked structure. Through coupling effects, this design has perfect ultra-wideband absorption characteristics. The absorber structure is composed of four absorption units with varying cycle lengths, which are cyclically stacked on the surface of the refractory metal Cr. Each cycle encompasses three-layer nanosheets of Ti-SiO 2 -GaAs. We verify through finite difference time domain method (FDTD) simulations that the absorber achieves an absorption efficiency of 97.8% within the wavelength range of 280 nm to 3000 nm, with an average efficiency of 96.6% under the AM1.5 standard solar spectrum. The absorber can achieve such a remarkable absorption effect because of surface plasmon resonance (SPR) and Fabry-Pérot resonance effects. At 1500 K, this structure exhibits a thermal radiation efficiency of up to 97.83%. Furthermore, the design is not affected by polarization and it is less affected by the incident angle of the light source. These absorption spectra remain consistent regardless of whether it is in the TE or TM mode. Even when the angle of incidence is increased to 60 degrees, the absorption efficiency remains high. Its unique structure and excellent performance characteristics provide higher solar energy efficiency. These outstanding features enable solar absorbers to have broad application potential in improving solar energy efficiency.

Electromagnetic metamaterials have demonstrated immense potential in the development of novel high-temperature wave-transparent materials, yet the requirements of their intricate structural design and strict stability pose dual challenges, particularly in high-speed radome applications. A strategy involving the synergistic modulation of boron nitride (BN) by dual metallic elements of Ca and Al (0.5Ca-0.5Al-BN) was proposed in this study, which elegantly integrates the advantages of metamaterial-like split ring resonator (SRR) features and h-BN's oxidation resistance enhancement. The highest wave transmittance at room temperature reaches 0.96 at 2-18 GHz. Notably, Al elements play a pivotal dual role in: (1) facilitating the solid solution of Ca to optimize the formation of metamaterial-like structures and (2) generating an amorphous Al 2 O 3 protective layer to preferentially defend against surface oxidation. This further prevents the breakdown of metamaterial characteristics at high temperatures, thereby striking a dual balance between the preservation of metamaterial-like structures and the high temperature stability of BN. Notably, 0.5Ca-0.5Al-BN retains its metamaterial-like characteristics, with a low permittivity not exceeding 2 even after exposure to 1500 °C oxidation. The corresponding wave transmission rate remains above 0.7 in most frequency bands at incidence angles of 0°, 10°, and 30°, ensuring superior wave-transparent properties. Furthermore, 0.5Ca-0.5Al-BN exhibits great hydrophobicity, benefiting resistance to rain and snow erosion. By integrating the merits between fundamental materials and metamaterials, this work transcends the limitations of conventional metamaterial design and offers fresh insights and empirical support for developing high-speed aircraft radome materials.

Carbenes are highly reactive intermediates central to various organic transformations, particularly within photochemistry. This study investigates siloxy carbenes generated from acyl silanes via a 1,2-silyl shift, focusing on their generation and reactivity in excited states, using the multiconfiguration perturbation theory (CASPT2//CASSCF/PCM). Our findings reveal that the presence of an aryl group conjugated with the carbonyl moiety substantially lowers the excitation energy of the singlet 1 nπ* state, enabling the 1,2-Brook rearrangement to proceed directly on the singlet hypersurface. This direct pathway, mediated by singlet S ΣP (σ 1 π 1 ) and S 0 (σ 2 π 0 ) carbenes, bypasses the need for intersystem crossing (ISC) to the triplet 3 nπ* state, which is the rate-determining step in the stepwise triplet pathway involving a triplet T ΣP (σ 1 π 1 ) carbene, thereby enhancing reaction rates and stereoselectivity by preventing undesired bond rotations. This contribution deepens the understanding of siloxy carbene reactivity and lays the groundwork for their future applications.

Terahertz devices play an irreplaceable role in the development of terahertz technology. However, at present, it is difficult for most natural materials to respond in the terahertz band, making the devices made of them perform poorly. In order to realize the diversity and tunability of device functions, we designed a terahertz metamaterial device composed of the thermally-induced phase change material VO 2 . The device structure is composed of a Au bottom layer, a SiO 2 dielectric layer and a VO 2 top layer. Through software simulation, we found that when T = 313 K, the device has complete reflection ability in the whole terahertz band. When T = 342 K, the average absorptivity is above 95% in the ultra-wide band range of 4.71-9.41 THz, and the absorptivity reaches an amazing 0.99999 at 6.31 THz. Thus, the maximum thermal modulation range of the device is 0.001-0.99999. The Bruggeman effective medium theory clarifies the phase transition characteristics of vanadium dioxide. The Drude model establishes the functional relationship between the conductivity of vanadium dioxide and temperature. The basic principle of high absorption was described using the impedance matching theory. We also drew the electric field intensity diagram during the temperature rise of the device to further confirm the reason for the change in the device performance. In addition, the influence of the absence of different structural layers on the absorptivity was simulated, which reflected the role of each layer structure more intuitively. We also explored the influence of the geometric size of the device on the absorptivity, which provided a certain reference value for practical application. In short, we have designed a tunable terahertz device with simple structure, high absorptivity, and wide absorption bandwidth, which can be used in the fields of energy collection, electromagnetic stealth, and modulation.

Metamaterial absorbers show great potential in many scientific and technological applications by virtue of their sub-wavelength and easy-to-adjust structure, with bandwidth as an important standard to measure the performance of the absorbers. In this study, our team designed a new broadband absorber, which consists of an indium arsenide (InAs) disk at the top, a zinc selenide (ZnSe)-chromium (Cr) stacked disk in the middle and a metal film at the bottom. Simulation results show that the absorber has remarkable absorptivity properties in the mid-long infrared band. In a wavelength range of 5.71-16.01 μm, the average absorptivity is higher than 90%. In the band of 5.86-15.49 μm, the absorptivity is higher than 95%. By simulating the electromagnetic field diagram at each resonant frequency, the reason for high broadband absorptivity is obtained. We also constructed Poynting vector diagrams to further elucidate this phenomenon. Next, we analyzed the influence of different materials and structural parameters on absorptivity properties and tested spectral response at different polarization angles and oblique incidence of the light source in the TM and TE modes. When the source is normally incident, the absorber shows polarization insensitivity. When the angle is 40°, absorptivity is still high, indicating that the absorber also possesses angle insensitivity. The broadband absorber proposed by us has good prospects in infrared detection and thermal radiators.

In situ monitoring of biological processes between different organelles upon oxidative stress is one of the most important research hotspots. Fluorescence imaging is especially suitable for biomedical applications due to its distinct advantages of high spatiotemporal resolution, high sensitivity, non-invasiveness, and in situ monitoring capabilities. However, most fluorescent probes can only achieve light-up imaging of single organelles, thus the combined use of two or more probes is usually required for monitoring biological processes between organelles, which can suffer from tedious staining and washing procedures, increased cytotoxicity and poor photostability. Exogenetic oxidants can affect broad-spectrum subcellular organelles, which are not conducive to in situ monitoring of biological processes between specific organelles. To tackle these challenges, a series of dual-/multi-organelle-targeted aggregation-induced emission (AIE) probes associated with oxidative stress have been designed and developed in the past few years. Herein, the recent progress of these AIE probes is summarized in biomedical applications, such as apoptosis monitoring, interplay between organelles, microenvironmental changes of organelles, organelle morphology tracking, precise cancer therapy, and so forth. Moreover, the further outlook for dual-/multi-organelle-targeted AIE probes is discussed, aiming to promote innovative research in biomedical applications.

Fumonisin B1 (FB1) is naturally present in the environment and can easily contaminate packaged foods during processing, storage and transportation, thus posing a threat to human health. We have developed an enzyme-free FB1 detector for the detection of packaged foods, which provides rapid and sensitive detection of FB1 in food. Gold nanoparticles (AuNPs; 5-10 nm) were uniformly dispersed on screen-printed electrodes, which acted as an excellent catalytic oxidizer. The surface structure of the modified electrode was characterized using scanning electron microscope and X-ray photoelectron spectroscopy. Differential pulse voltammetry demonstrated a good linear electrochemical response towards FB1 at concentrations ranging from 1 ng L -1 to 1 mg L -1 with a detection limit of 0.08 ng L -1 . We employed the AuNPs-SPE sensor to detect FB1-spiked packaged meat products achieving recovery rates ranging from 89.7% to 113.3%., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Natural organisms have evolved multi-scale wet gas sensing interfaces with optimized mass transport pathways in biological fluid environments, which sheds light on developing artificial counterparts with improved wet gas sensing abilities and practical applications. Herein, we highlighted current advances in wet gas sensing taking advantage of optimized mass transport pathways endowed by multi-scale interface design. Common moisture resistance ( e.g. , employing moisture resistant sensing materials, post-modifying moisture resistant coatings, physical heating for moisture resistance, and self-removing hydroxyl groups) and moisture absorption ( e.g. , employing moisture absorption sensing materials and post-modifying moisture absorption coatings) strategies for wet gas sensing were discussed. Then, the design principles of bioinspired multi-scale wet gas sensing interfaces were provided, including macro-level condensation mediation, micro/nano-level transport pathway adjustment and molecular level moisture-proof design. Finally, perspectives on constructing bioinspired multi-scale wet gas sensing interfaces were presented, which will not only deepen our understanding of the underlying principles, but also promote practical applications.

Microrobots, which can perform tasks in difficult-to-reach parts of the human body under their own or external power supply, are potential tools for biomedical applications, such as drug delivery, microsurgery, imaging and monitoring, tissue engineering, and sensors and actuators. Compared with traditional fabrication methods for microrobots, recent improvements in 3D printers enable them to print high-precision microrobots, breaking through the limitations of traditional micromanufacturing technologies that require high skills for operators and greatly shortening the design-to-production cycle. Here, this review first introduces typical 3D printing technologies used in microrobot manufacturing. Then, the structures of microrobots with different functions and application scenarios are discussed. Next, we summarize the materials (body materials, propulsion materials and intelligent materials) used in 3D microrobot manufacturing to complete body construction and realize biomedical applications ( e.g. , drug delivery, imaging and monitoring). Finally, the challenges and future prospects of 3D printed microrobots in biomedical applications are discussed in terms of materials, manufacturing and advancement.

Nucleophilic substitution is one of the most fundamental chemical reactions, and the pursuit of high reaction rates of the reaction is one of the ultimate goals in catalytic and organic chemistry. The reaction barrier of the nucleophilic substitution originates from the highly polar nature of the transition state that can be stabilized under the electric field created by the solvent environment. However, the intensity of the induced solvent-electric field is relatively small due to the random orientation of solvent molecules, which hinders the catalytic effects and restricts the reaction rates. This work shows that oriented external electric fields applied within a confined nanogap between two nanoscopic tips could accelerate the Menshutkin reaction by more than four orders of magnitude (over 39 000 times). The theoretical calculations reveal that the electric field inside the nanogap reduces the energy barrier to increase the reaction rate. Our work suggests the great potential of electrostatic catalysis for green synthesis in the future., Competing Interests: There is no conflict of interest to report., (This journal is © The Royal Society of Chemistry.)

Improving visible light absorption plays an important role in the utilization of solar power for photocatalysis. Using first-principles calculations within the HSE06 functional, we propose that the semiconductor heterojunction BiOI/LaOXI〈IX〉 extends the optical absorption to the near-infrared range, boosts the absorption coefficient from 1.28 × 10 5 cm -1 to above 2.20 × 10 5 cm -1 in the visible light range, and increases the conversion efficiency of solar power up to 9.48%. The enhanced optical absorption derives from the significant interlayer transition and excitonic effect which benefit from polarized LaOXI with a flat band in the highest valence band (VB). In BiOI/LaOClI〈ICl 〉, the electrostatic potential difference (Δ Φ ) modifies the band edge positions to meet the requirements for photocatalytic overall water splitting, while the polarized electric field ( E p ) accelerates the separation of photogenerated carriers and regulates the overpotentials of photogenerated carriers following a direct Z-scheme strategy. In addition, BiOI/LaOXI〈IX〉 is dynamically and thermodynamically stable. Furthermore, only a low external potential is needed to drive the redox reaction. Our theoretical results suggest that BiOI/LaOXI〈IX〉 could be a potential photocatalyst for overall water splitting with enhanced visible light absorption.

Hydrogels are widely utilized in the sensor field, but their inadequate adhesion presents a significant obstacle. Herein, a new multifunctional BNMFs/PAA composite hydrogel was prepared via the incorporation of one-dimensional porous boron nitride microfibers (BNMFs) and polyacrylic acid (PAA) hydrogels. BNMFs, as a reinforcing filler, play a very important role in enhancing the properties of the composite hydrogels. In particular, the porous micrometer structure plays a unique role in improving the adhesion properties of PAA hydrogels. The steric hindrance and the rich hydroxyl functional groups coming from BNMFs are key factors for the excellent adhesion of the composite hydrogels. The composite hydrogels show strong adhesion to various substrate materials. For iron plates and biological tissues, the adhesion energy can reach 1377 J m -2 and 317 J m -2 , respectively. In addition, the developed BNMFs/PAA composite hydrogels exhibit excellent mechanical properties. The fracture strain of the composite hydrogels is increased by 2.4 times compared to pure PAA hydrogels. The hydrogen bonds formed between BNMFs and PAA are conducive to the mechanical properties of the BNMFs/PAA composite hydrogels. Meanwhile, BNMFs as fillers play a role in carrying and dissipating force. Furthermore, the BNMFs/PAA composite hydrogels have excellent strain and pH response characteristics. This is because the crosslinking network of the composite hydrogels becomes loose after the addition of BNMFs, resulting in rapid ion transport pathways. Therefore, the developed BNMFs/PAA composite hydrogels will have broad application prospects in the fields of motion monitoring, intelligent skin and biological adhesives.

Iodine is one of the most effective sources for iodination of aromatic compounds; however, its electrophilicity is insufficient for direct iodination. The selection of appropriate environmentally friendly and cost-effective oxidants in combination with iodine for the iodination of aromatic rings, along with its application in the synthesis of natural products, holds significant importance. A highly efficient method utilizing I(III) as the initiator has been successfully developed for monoiodination of arylaldehydes. The method demonstrates good compatibility with a wide range of (hetero)aromatic aldehydes, resulting in moderate to excellent yields, without the need for any toxic, volatile or explosive reagents. The synthesis of seven natural products, namely aristogins A-F and hernandial, was achieved through this iodination followed by Ullmann-type coupling.

Flexible fiber electrodes offer new opportunities for bioelectronics and are reliable in vivo applications, high flexibility, high electrical conductivity, and satisfactory biocompatibility are typically required. Herein, we present an all-metal flexible and biocompatible fiber electrode based on a metal nanowire hybrid strategy, i.e. , silver nanowires were assembled on a freestanding framework, and further to render them inert, they were plated with a gold nanoshell. Our fiber electrodes exhibited a low modulus of ∼75 MPa and electrical conductivity up to ∼4.8 × 10 6 S m -1 . They can resist chemical erosion with negligible leakage of biotoxic silver ions in the physiological environment, thus ensuring satisfactory biocompatibility. Finally, we demonstrated the hybrid fiber as a neural electrode that stimulated the sciatic nerve of a mouse, proving its potential for applications in bioelectronics.

Currently, the surface structure modification of photocatalysts is one of the effective means of enhancing their photocatalytic efficiency. Therefore, it is critically important to gain a deeper understanding of how the surface of α-Fe 2 O 3 photocatalysts influences catalytic activity at the nanoscale. In this work, α-Fe 2 O 3 catalysts were prepared using the solvothermal method, and four distinct morphologies were investigated: hexagonal bipyramid (THB), cube (CB), hexagonal plate (HS), and spherical (RC). The results indicate that the hexagonal bipyramid (THB) exhibits the highest degradation activity towards tetracycline (TC), with a reaction rate constant of k = 0.0969 min -1 . The apparent reaction rate constants for the cube (CB), hexagonal plate (HS), and spherical (RC) morphologies are 0.0824, 0.0726, and 0.0585 min -1 , respectively. In addition, it has been observed that the enhancement of photocatalytic activity is closely related to the increase in surface area, which provides more opportunities for interactions between Fe 2+ and holes. The quenching experiments and electron paramagnetic resonance (EPR) results indicate that the ˙O 2 , ˙OH and h + contribute mainly to the degradation of TC in the system. This research contributes to a more comprehensive understanding of catalyst surface alterations and their impact on catalytic performance., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Uracil-DNA glycosylase (UDG) is a base excision repair (BER) enzyme, which catalyzes the hydrolysis of uracil bases in DNA chains that contain uracil and N -glycosidic bonds of the sugar phosphate backbone. The expression of UDG enzyme is associated with a variety of genetic diseases including cancers. Hence, the identification of UDG activity in cellular processes holds immense importance for clinical investigation and diagnosis. In this study, we employed Cas12a protein and enzyme-assisted cycle amplification technology with a test strip to establish a precise platform for the detection of UDG enzyme. The designed platform enabled amplifying and releasing the target probe by reacting with the UDG enzyme. The amplified target probe can subsequently fuse with crRNA and Cas12a protein, stimulating the activation of the Cas12a protein to cleave the signal probe, ultimately generating a fluorescent signal. This technique showed the ability for evaluating UDG enzyme activity in different cell lysates. In addition, we have designed a detection probe to convert the fluorescence signal into test strip bands that can then be observed with the naked eye. Hence, our tool presented potential in both biomedical research and clinical diagnosis related to DNA repair enzymes.

The negative Poisson's ratio (NPR) effect usually endows materials with promising ductility and shear resistance, facilitating a wider range of applications. It has been generally acknowledged that alloys show strong advantages in manipulating material properties. Thus, a thought-provoking question arises: how does alloying affect the NPR? In this paper, based on first-principles calculations, we systematically study the NPR in two-dimensional (2D) GaN and AlN, and their alloy of Al x Ga 1- x N. It is intriguing to find that the NPR in Al x Ga 1- x N is significantly enhanced compared to the parent materials of GaN and AlN. The underlying mechanism mainly originates from a counter-intuitive increase of the bond angle θ . We further study the microscopic origin of the anomalies by electron orbital analysis as well as electron localization functions. It is revealed that the distribution and movement of electrons change with the applied strain, providing a fundamental view on the effect of strain on lattice parameters and the NPR. The physical origin as revealed in this study deepens the understanding of the NPR and shed light on the future design of modern nanoscale electromechanical devices with fantastic functions based on the auxetic nanomaterials and nanostructures.

The electrochemical NO reduction reaction (NORR) towards NH 3 is considered a promising strategy to cope with both NO removal and NH 3 production. Currently, the research on NORR electrocatalysts mainly focuses on metal-based catalysts, while metal-free catalysts are quite scarce. In this work, we have systematically investigated the properties of pristine and C/O doped h-BN for efficient NO capture and reduction. Our results reveal that the basal plane of pristine h-BN is inert to the adsorption of NO, while doping C or O can significantly enhance the NO capture abilities of h-BN. Then, we highlight that C-doped h-BN exhibits excellent NORR catalytic performance with a relatively low limiting potential of -0.28 V. Further analysis shows that the suitable adsorption strength of NO on the C-doped h-BN surface is the prime reason for its excellent NO reduction activity, which is shown to be due to appropriate electronic interactions between the active site and NO. Last but not least, the catalytic selectivity of h-BN towards the NORR is confirmed by inhibiting the competing hydrogen evolution reaction. Our findings not only provide deeper insight into the essential effect of element doping on the catalytic activities of h-BN, but also propose general design principles for high-performance metal-free NORR electrocatalysts.

The spin-orbit interaction (SOI) plays an essential role in materials properties, and controlling its intensity has great potential in the design of materials. In this work, asymmetric [(La 0.7 Sr 0.3 MnO 3 ) 8 /(BaTiO 3 ) t /(SrTiO 3 ) 2 ] 8 superlattices were fabricated on (001) SrTiO 3 substrate with SrO or TiO 2 termination, labelled as SrO-SL and TiO 2 -SL, respectively. The in-plane angular magnetoresistance of the superlattices shows a combination of two- and four-fold symmetry components. The coefficient of two-fold symmetry component has opposite sign with current I along [100] and [110] directions for TiO 2 -SL, while it has the same sign for SrO-SL. Detailed study shows that the asymmetric cation inter-mixing and ferroelectricity-modulated electronic charge transfer induce asymmetric electronic potential for SrO-SL with dominating Rashba SOI, and symmetric electronic potential for TiO 2 -SL with dominating Dresselhaus SOI induced by BaTiO 3 . This work shows that the Rashba and Dresselhaus SOIs are sensitive to the ferroelectric polarization in the asymmetric structure.

Bacteria are introduced into natural gas transmission pipelines through water-driven gas extraction, which can exacerbate the occurrence of pipeline corrosion. This study utilized a micro-reactor to design a simulated corrosion environment that mimics natural gas gathering and transportation pipelines. The objective was to investigate the corrosion behavior of X80 pipeline steel under the combined effects of CO 2 , Cl-, sulfate reducing bacteria (SRB), and iron bacteria (IOB). Additionally, it aimed to elucidate the influence mechanisms of these two microorganisms on corrosion. Under a humid environment with a total pressure of 8.5 MPa and a partial pressure of CO 2 at 0.85 MPa, the corrosion rate of X80 pipeline steel was observed to follow the sequence: IOB > control (asepsis) > SRB + IOB > SRB. During the initial stages of corrosion, highly active IOB becomes the primary factor contributing to corrosion. As corrosion progresses, the concentration of dissolved oxygen in the SRB system gradually decreases while SRB activity intensifies, leading to the formation of FeS through the process of corrosion. The corrosion current density ( i corr ) exhibited a significant decrease, thereby intensifying localized corrosion of the corrosion products beneath the film. This resulted in a maximum pitting depth of 113.5 μm. Research on the behavior of microbial-enhanced corrosion provides significant guidance in the development and implementation of protective coatings., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Controlling the ratio of metals in bimetallic organic frameworks (MOFs) can not only alter the structures but also tailor the properties of MOFs. Herein, we report a series of electrocatalytically active Co x Ni y -based bimetallic MOFs that are synthesized with the 3,5-pyridinedicarboxylic acid (3,5-H 2 pdc) ligand (where x  :  y = 20 : 1, 15 : 1, 10 : 1, 5 : 1, 1 : 1, and 1 : 20) and a facile, scalable, low temperature synthetic route. The materials have one-dimensional (1D), rod-like microstructures with different aspect ratios. While they all electrocatalyze the oxygen evolution reaction (OER) in alkaline solution (1 M KOH), their electrocatalytic performances vary substantially depending on their compositions. The Co x Ni y -MOF with an optimal ratio of x  :  y = 15 : 1 (Co 15 Ni 1 -MOF) electrocatalyzes the OER with the highest maximum current density (92.2 mA cm -2 at 1.75 V vs. RHE) and the smallest overpotential (384 mV vs. RHE at 10 mA cm -2 ) in a 1 M KOH solution. It is also stable under constant current application during the electrocatalytic OER. This work demonstrates the application of bimetallic MOFs that are synthesized following a simple, low temperature synthetic route for the OER and their tailorable electrocatalytic properties for the OER by varying the ratio of two metals and the synthetic conditions used to produce them.

Many studies have shown that the severe photoluminescence quantum yield (PLQY) loss at the interface between the perovskite and electron transport layer (ETL) is the main cause of voltage loss in inverted perovskite solar cells (p-i-n PSCs). However, currently there are no effective in situ passivation techniques to minimize this nonradiative recombination. Here, the fluorinated pseudohalide ionic liquid (FPH-IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) is introduced into the perovskite precursor formulation. EMIMTFSI can change the dielectric environment and energy-level arrangement of the perovskite by accumulating on the top surface and spontaneously forming dipoles. As a result, the excitonic binding energy ( E b ) and nonradiative recombination loss are significantly reduced. At the same time, TFSI - and the C-F bond in EMIMTFSI. Finally, the EMIMTFSI-modified p-i-n PSCs achieve an excellent efficiency of 24.81% with an impressive open-circuit voltage of 1.191 V for a 1.57 eV low-bandgap perovskite. In addition, the modified devices can maintain more than 95% PCE after continuous thermal aging at 85 °C for 500 h or illumination at the maximum power point for 800 h. This work provides a new idea for minimizing the non-radiative recombination losses in p-i-n PSCs.+ and the C-F bond in EMIMTFSI. Finally, the EMIMTFSI-modified p-i-n PSCs achieve an excellent efficiency of 24.81% with an impressive open-circuit voltage of 1.191 V for a 1.57 eV low-bandgap perovskite. In addition, the modified devices can maintain more than 95% PCE after continuous thermal aging at 85 °C for 500 h or illumination at the maximum power point for 800 h. This work provides a new idea for minimizing the non-radiative recombination losses in p-i-n PSCs.

Polymer properties can be altered via lithium ion doping, whereby adsorbed Li + binds with H 2 O within the polymer chain. However, direct spectroscopic evidence of the tightness of Li + /H 2 O binding in the solid state is limited, and the impact of Li + on polymer sidechain packing is rarely reported. Here, we investigate a polystyrene/H 2 O/LiCl system using solid-state NMR, from which we determined a dipolar coupling of 11.4 kHz between adsorbed Li + and H 2 O protons. This coupling corroborates a model whereby Li + interacts with the oxygen atom in H 2 O via charge affinity, which we believe is the main driving force of Li + binding. We demonstrated the impact of hydrated Li + on sidechain packing and dynamics in polystyrene using proton-detected solid-state NMR. Experimental data and density functional theory (DFT) simulations revealed that the addition of Li + and the increase in the hydration levels of Li + , coupled with aromatic ring binding, change the energy barrier of sidechain packing and dynamics and, consequently, changes the glass transition temperature of polystyrene.

Inorganic metal chalcohalides, as significant semiconductor materials, have emerged as promising candidates for photoelectric applications. Herein, a new type of quaternary chalcohalide, [Ba 4 X][In 19 S 32 ] (X = Cl, Br), has been discovered using the high-temperature halide salt flux method. Single-crystal X-ray diffraction analysis reveals that they are isostructural and crystallize in the tetragonal space group I 4 1 / amd (no. 141) featuring the octahedral hole formed by six [InS 4 ] 5- tetrahedra filled with a [ClBa 4 ] 7+ polycation, surrounded by a three-dimensional covalent framework formed by interconnecting [InS 6 ] 9- octahedra through corner-sharing and edge-sharing. Moreover, [Ba 4 Cl][In 19 S 32 ] and [Ba 4 Br][In 19 S 32 ] exhibit wide optical bandgaps of 2.70 eV and 2.46 eV, respectively, and moderate birefringences (0.044 @ 2100 nm and 0.042 @ 2100 nm, respectively). Specifically, [Ba 4 X][In 19 S 32 ] (X = Cl, Br) display remarkable photocurrent responses under simulated solar-light illumination, implying their potential for photocatalytic applications. Theoretical calculations were employed to understand the interrelationship between the optical properties and electronic structure. The study on the synthesis and structure-property relationship analysis of inorganic metal chalcohalides provides new insight into the exploration of promising photoelectric materials.

Flexible humidity sensors have found new applications in diverse fields including human healthcare, the Internet of Things, and so on. In this paper, a highly sensitive humidity sensor based on carboxymethyl cellulose@graphene and conductive adhesive tape was developed. The sensor was constructed on conductive tape which acted as both of the flexible substrate and the electrode to transmit electronic signals. A carboxymethyl cellulose@graphene composite was assembled on the substrate as the sensing layer by a simple spreading method in a 3-D printed groove mold. The sensitive material was characterized for its morphology, composition, crystalline phase, and hydrophilicity by SEM, EDS, XRD, and contact angle measurements. The effect of graphene on the sensitivity was investigated in detail by adjusting the doping concentration. Humidity sensing performance was tested in different relative humidity levels. The rapid responses under different respiratory conditions demonstrated their practical usability in continuous respiration monitoring and recognition of respiratory status. The conductive mechanism of the sensing film was studied by complex impedance spectroscopy under different relative humidity levels. A rational sensing mechanism was proposed integrating ionic conduction, electron conduction and swelling behavior of the carboxymethyl cellulose@graphene composite., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

For long-term bedridden patients who need to wear diapers, the timely replacement of diapers is very important to ensure their quality of life. Therefore, it is urgent to develop a pressure sensor that can monitor the physiological conditions of patients in real time. Inspired by the multi-scale network structure of the multi-fiber protein in the muscle, a multi-scale hydrogel as a pressure sensor was prepared by introducing micron-scale hydrogel microspheres as physical crosslinking agents. Compared with the traditional polyacrylamide hydrogel (0.17 MPa of compressive strength), the multi-scale hydrogel showed a higher compressive strength of up to 1.37 MPa. Meanwhile, the hydrogel exhibited better pressure sensitivity (0.59 kPa -1 ) than the existing hydrogels (0.27-0.40 kPa -1 ). The sensor prepared by this hydrogel could monitor the patient's physiological condition (urine outflow and urinary filling) in real time through the conductivity response to ion concentration and pressure, and then transmit the signal to the caregivers in time to avoid skin damage. This multi-scale hydrogel provided a great convenience for the physiological monitoring of long-term bedridden patients by acting as a pressure sensor.

Y 2 O 3 is a promising material for use as a tritium permeation barrier (TPB) coating and as dispersed particles in oxide dispersion strengthened steels for experimental fusion reactors. By using first-principles approaches, we found that substituting Fe for Y in Y 2 O 3 is the most energetically favourable under O-deficient and H-rich conditions, leading to easier formation of the nearby O vacancies. These O vacancies serve as effective trapping sites for H atoms with a formation energy of -2.36 eV. The presence of Fe defects also makes it more difficult for H atoms to migrate in Y 2 O 3 from three possible H-related defects. These findings suggest that incorporating Fe into Y 2 O 3 could yield a better TPB and provide insight into the improved H trapping ability of Y 2 O 3 with Fe dopants.

The anti-washout ability of calcium phosphate cement (CPC) determines its effectiveness in clinical application. In the current research, the common method for improving the anti-washout ability of CPC is to add anti-washout polymer agents. Sodium polyacrylate powder is an excellent anti-washout agent but when bonded with CPC it basically degrades the anti-washout performance of CPC after γ-ray irradiation, and is widely used in the sterilization process of CPC products. Therefore, we propose a method for the preparation of a sodium polyacrylate solution through irradiation polymerization as curing solution for CPC. This method first uses γ-ray irradiation sterilization to improve the anti-washout ability of CPC directly. It not only avoids the adverse effects of γ-rays on anti-washout agents, but also the CPC blended using this sodium polyacrylate solution had good biological properties and injectability. It provides a new method for promoting the anti-washout properties of calcium phosphate cement, which is of great significance for expanding the clinical application of CPC.

Hydrogel robots are widely used in biomedical fields due to their excellent biocompatibility and response to external stimuli. However, traditional processing methods cannot rapidly fabricate complex structures, and smart response strategies often rely on double-layer structures fabricated from two materials with significantly different swelling properties. In this study, we present a single-layer hydrogel robot that can be fabricated in one step using a high-precision digital light processing (H-P DLP) 3D printing system. The robot has structural differences and the ability to maintain a repetitive response. Additionally, we fabricated several robot grippers to demonstrate their potential for customization and programming, as well as their potential applications in cargo delivery. Our work provides a new approach to achieve the formation and response of various irregular hydrogels, which is expected to advance the development of biomedical applications.

Holography is an important topic in optical research. Metasurface holography has attracted increasing attention in recent years. However, it is still challenging to achieve dynamic tuning of holograms in the terahertz band. As an excellent phase change material, vanadium dioxide (VO 2 ) is widely employed to dynamically manipulate electromagnetic waves. Here, VO 2 meta-atoms are designed to manipulate phase and amplitude by changing the state of VO 2 at 3.0 THz. These meta-atoms are composed of a VO 2 block, silica spacer, and gold substrate. As the metallic VO 2 is involved, 360° phase coverage is achieved by changing the dimension of VO 2 . The phase difference between the VO 2 meta-atoms is approximately equal to 90°. Holograms are generated by aligning these meta-atoms. By combining convolution operations, holograms are deflected and reproduced. As the insulating VO 2 is involved, the phase difference between the VO 2 meta-atoms vanishes and the reflection amplitudes of the meta-atoms almost reach 100%. Using the phase transition of VO 2 , three types of metasurfaces are designed to manipulate holograms and they realize state switching of the hologram generator, state switching of hologram deflection, and state switching of the multi-beam hologram. Our work may find applications in optical holography and information privacy.

Stability is a key factor that restricts the practical applications of metal-organic framework (MOF) materials. In this work, we report an ultrastable three-dimensional cage-like MOF, SrCu(HC 3 N 3 O 3 ) 2 , constructed by a polydentate cyanurate ligand and two kinds of different metal nodes. A high ratio of coordination sites in organic ligands, specific coordination of strong acid with a strong base and weak acid with a weak base and double independent completed coordination networks endow SrCu(HC 3 N 3 O 3 ) 2 with outstanding thermal stability (up to 300 °C) and acid/alkali resistance (pH = 2-14). Moreover, SrCu(HC 3 N 3 O 3 ) 2 possesses the highest porosity up to 36.7% among cyanuric acid-based MOF materials and exhibits differentiated adsorption of C 3 H 4 (63 cm 3 g -1 ) and C 3 H 6 (51 cm 3 g -1 ). The breakthrough experiment further verified that efficient C 3 H 4 /C 3 H 6 separation can be achieved under dynamic conditions by SrCu(HC 3 N 3 O 3 ) 2 .

We propose a novel strategy for the synthesis of pyruvic acid from bio-lactic acid in air. Polyvinylpyrrolidone can regulate the growth of the crystal face and formation of oxygen vacancies, in which a synergy of the facet and vacancies boosted the oxidative dehydrogenation of lactic acid into pyruvic acid.

The health hazards caused by low concentrations of Pb 2+ ions in drinking water systems are of significant concern. In order to remove Pb 2+ ions and retain Na + , K + , Ca 2+ and Mg 2+ as harmless competitive ions without simultaneous removal, nickel foam (NF)/Mn 2 CoO 4 @tannic acid (TA)-Fe 3+ electrodes were prepared by a hydrothermal method and a coating method and an asymmetric capacitive deionization (CDI) system is established using the prepared electrodes and a graphite paper positive electrode. The designed asymmetric CDI system exhibited a high Pb 2+ adsorption capacity of 375 mg g -1 with high removal efficiency and significant regeneration behavior at 1.4 V at neutral pH. When the asymmetric CDI system is used to enrich a hydrous solution of mixed Na + , K + , Ca 2+ , Mg 2+ and Pb 2+ ions each with a concentration of 10 ppm and 100 ppm by electrosorption at a 1.4 V operating voltage, the removal rate of Pb 2+ is as high as 100% and 70.8% respectively, and the relative selectivity coefficients are 4.51-43.22. According to the different adsorption mechanisms of lead ions and coexisting ions, the separation and recovery of ions can be realized by a two-step desorption process, thereby providing a new method for removing Pb 2+ ions from drinking water with excellent application potential.

Two-dimensional (2D) ferroelectricity, a fundamental concept in low-dimensional physics, serves as the basis of non-volatile information storage and various electronic devices. Conventional 2D ferroelectric (FE) materials are usually two-fold degenerate, meaning that they can only store two logical states. In order to break such limitation, a new concept of highly degenerate ferroelectricity with multiple FE states (more than 2) coexisting in a single 2D material is proposed. This is obtained through the asymmetrical decoration of porous covalent/metal organic frameworks (COFs/MOFs). Using first-principles calculations and Monte Carlo (MC) simulations, Li-decorated 2D Cr(pyz) 2 is systematically explored as a prototype of highly degenerate 2D FE materials. We show that 2D FE Li 0.5 Cr(pyz) 2 and LiCr(pyz) 2 are four-fold and eight-fold degenerate, respectively, with sizable spontaneous electric polarization that can be switched across low transition barriers. In particular, the coupling between neighbouring electric dipoles in LiCr(pyz) 2 induces novel ferroelectricity-controlled ferroelastic transition and direction-controllable hole transport channels. Moreover, three-fold and six-fold degenerate ferroelectricity is also demonstrated in P-decorated g-C 3 N 4 and Ru-decorated C 2 N, respectively. Our work presents a general route to obtain highly degenerate 2D ferroelectricity, which goes beyond the two-state paradigm of traditional 2D FE materials and substantially broadens the applications of 2D FE compounds.

Unhealthy dietary pattern-induced type 2 diabetes mellitus poses a great threat to human health all over the world. Accumulating evidence has revealed that the pathophysiology of type 2 diabetes mellitus is closely associated with the dysregulation of glucose metabolism and energy metabolism, serious oxidative stress, prolonged endoplasmic reticulum stress, metabolic inflammation and intestinal microbial dysbiosis. Most important of all, insulin resistance and insulin deficiency are two key factors inducing type 2 diabetes mellitus. Nowadays, natural polysaccharides have gained increasing attention owing to their numerous health-promoting functions, such as hypoglycemic, energy-regulating, antioxidant, anti-inflammatory and prebiotic activities. Therefore, natural polysaccharides have been used to alleviate diet-induced type 2 diabetes mellitus. Specifically, this review comprehensively summarizes the underlying hypoglycemic mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates hypoglycemic mechanisms of natural polysaccharides from the perspectives of their regulatory effects on glucose metabolism, insulin resistance and mitochondrial dysfunction.

Metal thiophosphates have outstanding properties for the generation of mid-infrared coherent light and are an emerging nonlinear optical material system. In this study, a new non-centrosymmetric (NCS) quaternary alkaline-earth metal thiophosphate, SrAgPS 4 , was obtained via a high-temperature solid-state method. The new compound crystallizes in the NCS Ama 2 (No. 40) space group and features two-dimensional [AgPS 4 ] 2- layers consisting of alternately connected [PS 4 ] and [AgS 4 ] tetrahedra. SrAgPS 4 exhibits a strong phase-matched second harmonic generation response (1.10 × AgGaS 2 at 2100 nm) and a large band gap (2.97 eV). In addition, theoretical calculations reveal the intrinsic relationship between the electronic structure and optical properties. This work enriches and greatly promotes the research on infrared nonlinear optical materials based on thiophosphates.

Histopathology evaluation and lymphadenectomy of node-positive patients is the usual procedure in clinical therapy. However, it requires days for the histopathology result analysis, which impedes intraoperative decision-making and immediate treatment. Noninvasive real-time imaging of metastatic lymph nodes can overcome these defects and help medical workers evaluate lymph nodes and make the operation decision more efficiently. Herein we developed iridium(III)-cyanine complex/bovine serum albumin (BSA)-based nanoparticles which are conjugated with folic acid (FA) (IrCy-FA NPs). The synthesized IrCy-FA NPs exhibit good biocompatibility, strong near-infrared absorption, and impressive lymph node accumulation and can serve as a photoacoustic (PA) imaging probe for lymph node imaging. Besides, the lymph nodes enriched with IrCy-FA NPs showing green color are easily visible to the naked eye, suggesting their potential as an intraoperative indicator. The real-time PA imaging with excellent contrast and high spatial resolution can promote efficient and reliable quantitative analysis of lymph nodes in vivo . By employing IrCy-FA NPs as the PA agent for lymph node imaging, we achieve effective pre-operative and post-operative evaluations of metastatic lymph nodes in lymphadenectomy. This study may provide helpful information for PA imaging guided colocalization and evaluation of lymph nodes and facilitate this method towards clinical trials.

A simple and effective method for the copper-catalyzed selective C5-H bromination and difluoromethylation of 8-aminoquinoline amides with ethyl bromodifluoroacetate as the bifunctional reagent was developed. The combination of cupric catalyst and alkaline additive results in a C5-bromination reaction, whereas cuprous catalyst combined with silver additive results in the C5-difluoromethylation reaction. This method has a broad substrate scope and allows for easy and convenient access to desired C5-functionalized quinolones with good to excellent yields., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Large preclinical evidence suggested that colitis was one of the risk factors for depression and probiotics were effective therapeutic agents to prevent the disease. The effect of Lacticaseibacillus rhamnosus Fmb14 on colitis-related depression-like behavior and its possible mechanisms were investigated. One week of DSS exposure led to the following changes in male C57BL/6N mice: a reduction in the movement distance from 2218 to 1299 cm, time in central areas from 23.6 s to 11.5 s, and time in the bright box from 217 s to 103 s, which were restored to 1816 cm, 18.4 s, and 181 s, respectively, with preadministration of Fmb14 for 8 weeks. All improvements provided by Fmb14 indicated a remarkable protective effect on depression-like behavior. Fmb14 first worked to repair intestinal barrier damage and the inflammatory response in the colon through ZO1 and Ocln enhancement and IL-1β, NF-κB and IL-6 reduction, respectively. Second, dysbiosis of the gut microbiota was modulated by Fmb14, including reduction of Akkermansia (18.9% to 5.4%), Mucispirillum (0.6% to 0.1%) and Bifidobacterium (0.32% to 0.03%). Fmb14 supplementation ameliorates the brain inflammatory response via IL-18 and NF-κB reduction and improves the blood-brain barrier via increased levels of ZO1 and Ocln. Moreover, brain activity was facilitated by an increase in BDNF and dopamine and the downregulation of GABA in the Fmb14 group. As a consequence of the modulatory effect on the dysfunction of neurotransmitters and neuroinflammation, Fmb14 prevents neurodegeneration by inhibiting neuronal apoptosis and Nissl edema. In addition, the correlation analysis further demonstrated the preventative effect of Fmb14 on depression-like behavior through the microbiota-gut-brain axis. Together, these findings demonstrated the important role of Fmb14 in biological signal transduction over the microbiota-gut-brain axis to improve mood disorders.

The structure of CsPbI 3 nanocrystals (NCs) with excellent photoelectric properties easily collapses, which hinders their application in light-emitting diodes (LEDs). Herein, we accomplished the synthesis of efficient and stable CsPbI 3 NCs by regulating structural rigidity under the synergistic effect of Mg 2+ and AcO - ions. The introduced AcO - and Mg 2+ ions increase surface steric hindrance and defect formation energy, which enhances the structural rigidity of the perovskite. As a result, the CsPbI 3 NCs display an outstanding photoluminescence quantum yield of 95.7%, in conjunction with reduced defect state density, balanced carrier injection, and distinguished conductivity. Remarkably, the modified CsPbI 3 NCs exhibit excellent stability under ambient conditions for 180 days and can even survive when the temperature reaches 150 °C. Given their enhanced structural rigidity, LEDs made from these modified CsPbI 3 NCs exhibit a maximum luminance and an EQE of 3281 cd m -2 and 13.2%, respectively, which are significantly improved compared with those of unmodified CsPbI 3 NC LEDs.

A new composite hydrogel adsorbent for adsorption of Pb 2+ has been prepared by combining porous boron nitride nanofibers (BNNFs) and the acrylamide and sodium acrylate copolymer (P(AANa- co -AM)) via a chemical crosslinking method. Porous BNNFs with abundant hydroxyl functional groups can form hydrogen bond interactions with carboxyl and amino functional groups of the copolymer in the composite hydrogel and carry and dissipate forces for the composite hydrogels. So the mechanical performances of the copolymer hydrogels can be effectively improved, which is very valuable for the practical application of the composite hydrogel to remove Pb 2+ from waste water. The thermal stability and swelling performance of the pure copolymer hydrogels were also greatly improved. This is not only because of the strong hydrogen bond interactions but also the good thermal stability and flexibility of BNNFs. The composite hydrogel adsorbent shows superior adsorption capacity for Pb 2+ (490.2 mg g -1 ) to most of the reported hydrogel adsorbents. The chemisorption dominates the whole adsorption process according to the pseudo-second-order kinetic and the Langmuir models. The composite hydrogel adsorbent also shows good reusability. Therefore, we believe that the prepared composite hydrogels will play an important role in removing Pb 2+ from wastewater.

Antibodies against poly(ethylene glycol) (PEG) have been found to be the culprit of side reactions and efficacy loss of a number of PEGylated drugs. Fundamental mechanisms of PEG immunogenicity and design principles for PEG alternatives still have not been fully explored. By using hydrophobic interaction chromatography (HIC) under varied salt conditions, we reveal the "hidden" hydrophobicity of those polymers which are generally considered as hydrophilic. A correlation between the hidden hydrophobicity of a polymer and its polymer immunogenicity is observed when this polymer is conjugated with an immunogenic protein. Such a correlation of hidden hydrophobicity vs. immunogenicity for a polymer also applies to corresponding polymer-protein conjugates. Atomistic molecular dynamics (MD) simulation results show a similar trend. Based on polyzwitterion modification and with this HIC technique, we are able to produce extremely low-immunogenic protein conjugates as their hydrophilicity is pushed to the limit and their hydrophobicity is eliminated, breaking the current barriers of eliminating anti-drug and anti-polymer antibodies., Competing Interests: S. J. is a co-founder of ZWI therapeutics. S. J. and Z. Y. are listed as inventors on a provisional patent application filed by Cornell University., (This journal is © The Royal Society of Chemistry.)

New strategies for the design and synthesis of stable organic radicals without additives are highly desirable. Herein, we design a series of donor-acceptor structured triarylphosphines and disclose the fast color change triggered by UV-irradiation in the crystalline state. Photoinduced organic radicals are undoubtedly verified and proved to be the reason for the color change by time-dependent and quantitative electron paramagnetic resonance analysis, X-ray crystallographic analysis, and theoretical calculations. It is revealed that the intrinsic symmetry breaking of peripheral architecture helps to form continuous molecular chains by donor-acceptor counterpart pairing. Intermolecular electron-transfer occurs among molecular chains and results in radical ion pairs upon photoirradiation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)