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Topological spin textures are of great significance in magnetic information storage and spintronics due to their high storage density and low drive current. In this work, the transformation of magnetic configuration from chaotic labyrinth domains to uniform stripe domains was observed in MnFe 1- x Co x Ge magnets. This change occurs due to the noncollinear magnetic structure switching to a uniaxial ferromagnetic structure with increasing Co content, as identified by neutron diffraction results and Lorentz transmission electron microscopy (L-TEM). Of utmost importance, a hexagonal lattice of high-density robust type-II magnetic bubble lattice was established for x = 0.8 through out-of-plane magnetic field stimulation and field-cooling. The dimensions of the type-II magnetic bubbles were found to be tuned by the sample thickness. Therefore, the stabilization of complex magnetic spin textures, associated with enhanced uniaxial ferromagnetic interaction and magnetic dipole-dipole interaction in MnFe 1- x Co x Ge through magnetic structure manipulation, as further confirmed by the micromagnetic simulations, will provide a convenient and efficient strategy for designing topological spin textures with potential applications in spintronic devices.

Copper-based catalysts have been attracting increasing attention for CO 2 electroreduction into value-added multicarbon chemicals. However, most Cu-based catalysts are designed for ethylene production, while ethanol production with high Faradaic efficiency at high current density still remains a great challenge. Herein, Cu clusters supported on single-atom Cu dispersed nitrogen-doped carbon (Cu x /Cu-N/C) show ethanol Faradaic efficiency of ∼40% and partial current density of ∼350 mA cm -2 . Quasi in situ X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy results suggest the generation of surface asymmetrical sites of Cu + and Cu 0 as well as Cu clusters by electrochemical reduction and reconstruction during the CO 2 electroreduction process. Density functional theory calculations indicate that the interaction between Cu clusters and the Cu-N/C support enhances *CO adsorption, facilitates the C-C coupling step, and favors the hydrogenation rather than dehydroxylation of the critical intermediate *CHCOH toward ethanol in the bifurcation.

Cathodic CO 2 adsorption and activation is essential for high-temperature CO 2 electrolysis in solid oxide electrolysis cells (SOECs). However, the component of oxygen ionic conductor in the cathode displays limited electrocatalytic activity. Herein, stable single Ruthenium (Ru) atoms are anchored on the surface of oxygen ionic conductor (Ce 0.8 Sm 0.2 O 2-δ , SDC) via the strong covalent metal-support interaction, which evidently modifies the electronic structure of SDC surface for favorable oxygen vacancy formation and enhanced CO 2 adsorption and activation, finally evoking the electrocatalytic activity of SDC for high-temperature CO 2 electrolysis. Experimentally, SOEC with the Ru 1 /SDC-La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ cathode exhibits a current density as high as 2.39 A cm -2 at 1.6 V and 800 °C. This work expands the application of single atom catalyst to the high-temperature electrocatalytic reaction in SOEC and provides an efficient strategy to tailor the electronic structure and electrocatalytic activity of SOEC cathode at the atomic scale., (© 2023 Wiley-VCH GmbH.)

Redox reaction of the monovalent Rh 2 (CO) 4 Cl 2 and Bi n n - ( n = 2, 3) from K 5 Bi 4 in ethylenediamine ( en ) solution produced the decabismuthide-hexarhodium dianion [Rh@Bi 10 (RhCO) 5 ] 2- (1a) wherein a novel Bi 10 -bowl was constructed from oxidized 2Bi 3 /2Bi 2 open triangles/dimers, which was stabilized by strong bonding to a reduced Rh@(RhCO) 5 square pyramid. Two 1a dianons are held together by weak interactions (van der Waals forces and spatial resistance) to form a dimer [Rh@Bi 10 (RhCO) 5 ] 2 4- (1). The structure and bonding of the novel polybismuthide heteroanion 1 are discussed.

Mo 2 C demonstrates excellent performance in catalysis, and it has been found to possess excellent hydrogen evolution reaction (HER) catalytic activity and highly efficient nitrogen fixation. The catalytic activity of Mo 2 C is greatly influenced and restricted by the preparation method. Sintering and carbon deposition, which affect the catalytic activity of Mo 2 C, are inevitable in the traditional vapor-solid-solid (VSS) process. In this study, we report the controllable synthesis of α-Mo 2 C micron flowers by adjusting the growth temperature via a vapor-liquid-solid (VLS) process. The density of the Mo 2 C micron flowers is closely related to the concentration of Na 2 MoO 4 aqueous solution. The as-grown Mo 2 C micron flowers dispersed with Pt are validated to be an enhanced collaborative electrocatalyst for HER against Pt/VSS-Mo 2 C., 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.)

This paper analyzes how housing prices affect innovation and entrepreneurship. We construct a city-level panel dataset including 281 cities between 2009 and 2019 by merging housing price data from China Statistical Yearbook for Regional Economy with innovation and entrepreneurship data from Peking University Open Research Data Platform. Our results suggest that housing prices are positively associated with the vitality of innovation and entrepreneurship (VIE). The results remain consistent with a series of robustness checks. We also find that rising house prices promote VIE through the wealth effect and the siphon effect. Spatial effect analysis further shows that housing prices not only positively affect the VIE of local cities, but also positively affect the VIE of neighboring cities. These findings imply the necessity of curbing the excessive rise of housing prices and decoupling public services and benefits related to homeownership., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Fan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The increasing miniaturization of electronics requires a better understanding of material properties at the nanoscale. Many studies have shown that there is a ferroelectric size limit in oxides, below which the ferroelectricity will be strongly suppressed due to the depolarization field, and whether such a limit still exists in the absence of the depolarization field remains unclear. Here, by applying uniaxial strain, we obtain pure in-plane polarized ferroelectricity in ultrathin SrTiO_{3} membranes, providing a clean system with high tunability to explore ferroelectric size effects especially the thickness-dependent ferroelectric instability with no depolarization field. Surprisingly, the domain size, ferroelectric transition temperature, and critical strain for room-temperature ferroelectricity all exhibit significant thickness dependence. These results indicate that the stability of ferroelectricity is suppressed (enhanced) by increasing the surface or bulk ratio (strain), which can be explained by considering the thickness-dependent dipole-dipole interactions within the transverse Ising model. Our study provides new insights into ferroelectric size effects and sheds light on the applications of ferroelectric thin films in nanoelectronics.

The design of efficient copper(Cu)-based catalysts is critical for CO 2 electroreduction into multiple carbon products. However, most Cu-based catalysts are favorable for ethylene production while selective production of ethanol with high Faradaic efficiency and current density still remains a great challenge. Herein, we design a carbon-coated CuO x (CuO x @C) catalyst through one-pot pyrolysis of Cu-based metal-organic framework (MOF), which exhibits high selectivity for CO 2 electroreduction to ethanol with Faradaic efficiency of 46 %. Impressively, the partial current density of ethanol reaches 166 mA cm -2 , which is higher than that of most reported catalysts. Operando Raman spectra indicate that the carbon coating can efficiently stabilize Cu + species under CO 2 electroreduction conditions, which promotes the C-C coupling step. Density functional theory (DFT) calculations reveal that the carbon layer can tune the key intermediate *HOCCH goes the hydrogenation pathway toward ethanol production., (© 2022 Wiley-VCH GmbH.)

Recent realizations of ultrathin freestanding perovskite oxides offer a unique platform to probe novel properties in two-dimensional oxides. Here, we observe a giant flexoelectric response in freestanding BiFeO 3 and SrTiO 3 in their bent state arising from strain gradients up to 3.5 × 10 7  m -1 , suggesting a promising approach for realizing ultra-large polarizations. Additionally, a substantial change in membrane thickness is discovered in bent freestanding BiFeO 3 , which implies an unusual bending-expansion/shrinkage effect in the ferroelectric membrane that has never been seen before in crystalline materials. Our theoretical model reveals that this unprecedented flexural deformation within the membrane is attributable to a flexoelectricity-piezoelectricity interplay. The finding unveils intriguing nanoscale electromechanical properties and provides guidance for their practical applications in flexible nanoelectromechanical systems., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

The electrochemical CO 2 reduction reaction (CO 2 RR) over Cu-based catalysts shows great potential for converting CO 2 into multicarbon (C 2+ ) fuels and chemicals. Herein, we introduce an A 2 M 2 O 7 structure into a Cu-based catalyst through a solid-state reaction synthesis method. The Cu 2 P 2 O 7 catalyst is electrochemically reduced to metallic Cu with a significant structure evolution from grain aggregates to highly porous structure under CO 2 RR conditions. The reconstructed Cu 2 P 2 O 7 catalyst achieves a Faradaic efficiency of 73.6 % for C 2+ products at an applied current density of 350 mA cm -2 , remarkably higher than the CuO counterparts. The reconstructed Cu 2 P 2 O 7 catalyst has a high electrochemically active surface area, abundant defects, and low-coordinated sites. In situ Raman spectroscopy and density functional theory calculations reveal that CO adsorption with bridge and atop configurations is largely improved on Cu with defects and low-coordinated sites, which decreased the energy barrier of the C-C coupling reaction for C 2+ products., (© 2021 Wiley-VCH GmbH.)

Interfacial thermal transport plays a prominent role in the thermal management of nanoscale objects and is of fundamental importance for basic research and nanodevices. At metal/insulator interfaces, a configuration commonly found in electronic devices, heat transport strongly depends upon the effective energy transfer from thermalized electrons in the metal to the phonons in the insulator. However, the mechanism of interfacial electron-phonon coupling and thermal transport at metal/insulator interfaces is not well understood. Here, the observation of a substantial enhancement of the interfacial thermal resistance and the important role of surface charges at the metal/ferroelectric interface in an Al/BiFeO 3 membrane are reported. By applying uniaxial strain, the interfacial thermal resistance can be varied substantially (up to an order of magnitude), which is attributed to the renormalized interfacial electron-phonon coupling caused by the charge redistribution at the interface due to the polarization rotation. These results imply that surface charges at a metal/insulator interface can substantially enhance the interfacial electron-phonon-mediated thermal coupling, providing a new route to optimize the thermal transport performance in next-generation nanodevices, power electronics, and thermal logic devices., (© 2021 Wiley-VCH GmbH.)

pH-sensitive hydrogels have been applied in delivering probiotics and drugs. However, pH sensitivity has been found to be contradictory with structural stability in hydrogel preparation. In this work, a novel strategy based on two systems of sodium carboxymethyl cellulose (CMC)/chitosan (CS) and sodium alginate (SA)/calcium chloride was designed to construct a reticulated shell structure stable for 3 h in simulated gastric fluid (pH 1.2) but began to break up at 2 h in simulated intestinal fluid (pH 6.8), exhibiting obvious pH sensitivity. The embedding rate of Bacillus subtilis natto reached to 67.3%, and the sustained release lasted for more than 10 h. It is implicated that the reticulated shell structure has harmoniously balanced the two incompatible properties of pH sensitivity and sustained release of CMC/CS/SA beads., (Copyright © 2021. Published by Elsevier B.V.)

A digital image (DI) method is reported to determine the transmittance and the uniformity of transparent optical materials (TOMs) at the same time, in which an objective image (OI) with a two dimensional (2D) entropy of 3.45 is scanned using a scanner with a black background. The OI pictures covered without and with a TOM went through gamma correction and color correction. The two corrected pictures were transformed into two matrixes, between which the transparency ratio and the correlation coefficient refer to the transmittance and the uniformity of TOMs. As a result, a p -value of 0.97 and an r value of 0.92 were achieved from the paired T -test between the DI method and the ultraviolet spectrometry (UVS) method, indicating a similar accuracy in determining the transmittance of TOMs between them. In addition, the DI method is a simple and rapid method to evaluate the uniformity of TOMs and to reveal the correlation among transmittance, uniformity and thickness of TOMs, particularly applicable for inhomogeneous TOMs.

Presently, there have been some limitations in most of methods to determine poly (γ-glutamic acid) (γ-PGA) content because of many impurities in test specimens. It is necessary to establish a rapid and accurate method to quantify γ-PGA content. In this work, γ-PGA and some impurities commonly seen in fermented broth like glucose, glutamic acid and proteins were used to complex with copper ions. The results show that only γ-PGA can make copper ion precipitated, which content linearly correlates with the precipitate amount. From the study on the validity of the method, it is found that the accuracy and precision are 95.82% and 99.29%, much higher than the ones of method UV and weighing. Therefore, the method via the complexation of copper ion will be popularized to determine γ-PGA content in crude biological samples., Competing Interests: Declaration of competing interest None., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: To study the effect of nattokinse (NK) on the synthesis of poly(γ-glutamic acid) (γ-PGA) in Bacillus subtilis natto., Results: γ-PGA yield significantly decreased as NK was added in the original medium. With the increment of NK dosage, the yield decreased increasingly, but biomass increased instead of decreasing. The fact that cell density triggers the synthesis of γ-PGA is a controversial issue. γ-PGA yield and biomass closely correlate with addition time of NK. The later the addition of NK, the more γ-PGA yield decreased but the more biomass increased. It is concluded that cell hunger is a key factor to trigger the transmission of the cell density signal, and NK may inhibit γ-PGA synthesis by alleviating cell hunger. Besides, NK may reduce γ-PGA yield by degrading extracellular γ-PGA molecules. The study of adding L-glutamate of 0-20 g/L to the original medium showed that low concentration of L-glutamate (less than 5 g/L) could promote the synthesis of NK and γ-PGA, and thus NK may inhibit γ-PGA synthesis through strengthening substrate competition., Conclusions: NK mainly inhibits γ-PGA synthesis in Bacillus subtilis natto through alleviating cell starvation and strengthening substrate competition, and reduces γ-PGA yield through degrading extracellular γ-PGA molecules.

A porous chitosan (CS)/poly-(γ-glutamic acid) (γ-PGA) hydrogel was prepared by polymerization by electrostatic contacts of CS with γ-PGA without linker. The porosity of the hydrogel remarkably depends on γ-PGA content, pH regulator, and drying way. The optimization of them had given the hydrogel a high swelling capacity of 1398%, 11-fold higher than that of neat CS hydrogel. The hydrogel was applied to recover bovine serum albumin (BSA) from aqueous solution, and its adsorption capacity was influenced by the initial concentration and pH of BSA solution. Based on the studies of kinetics and isotherm, a high equilibrium adsorption capacity (q e  = 948 mg/g) and a correlation coefficient of 0.996 were calculated from pseudo-second order kinetic equation, and a high affinitive constant (k F  = 472 mL/mg) and a high saturated absorption capacity (q m  = 1818.5 mg/g) were observed from Freundlich isotherm equation, indicating the porous hydrogel will be a good absorbent for protein recovery from sewage., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The capability of manipulating the interfacial electronic coupling is the key to achieving on-demand functionalities of catalysts. Herein, it is demonstrated that the electronic coupling of Fe 2 N can be effectively regulated for hydrogen evolution reaction (HER) catalysis by vacancy-mediated orbital steering. Ex situ refined structural analysis reveals that the electronic and coordination states of Fe 2 N can be well manipulated by nitrogen vacancies, which impressively exhibit strong correlation with the catalytic activities. Theoretical studies further indicate that the nitrogen vacancy can uniquely steer the orbital orientation of the active sites to tailor the electronic coupling and thus benefit the surface adsorption capability. This work sheds light on the understanding of the catalytic mechanism in real systems and could contribute to revolutionizing the current catalyst design for HER and beyond., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

P-rich transition metal phosphides (TMPs) with abundant P sites have been predicted to be more favorable for hydrogen evolution reaction (HER) catalysis. However, the actual activities of P-rich TMPs do not behave as expected, and the underlying essence especially at the atomic level is also ambiguous. Our structural analysis reveals the inferior activity could stem from the reduced overlap of atomic wave functions between metal and P with the increase in P contents, which consequently results in too strong P-H interaction. To this end, we used N-induced lattice contraction to generally boost the HER catalysis of P-rich TMPs including CoP 2 , FeP 2 , NiP 2 , and MoP 2 . Refined structural characterization and theoretical analysis indicate the N-P strong interaction could increase the atomic wave function overlap and eventually modulate the H adsorption strength. The concept of lattice engineering offers a new vision for tuning the catalytic activities of P-rich TMPs and beyond., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Currently, it is in urgent need to develop novel selective PDE4 inhibitors with novel structural scaffolds to overcome the adverse effects and improve the efficacy. Novel 1-phenyl-3,4-dihydroisoquinoline amide derivatives were developed as potential PDE4 inhibitors based on the structure-based drug design and fragment identification strategy. A SARs analysis was performed in substituents attached in the C-3 side chain phenyl ring, indicating that the attachment of methoxy group or halogen atom substitution at the ortho-position of the phenyl ring was helpful to enhance both inhibitory activity toward PDE4B and selectivity. Compound 15 with excellent selectivity, exhibited the most potent inhibition in vitro and in vivo, which is a promising lead for development of a new class of selective PDE4 inhibitors., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Two-dimensional (2D) materials such as graphene and transition-metal dichalcogenides reveal the electronic phases that emerge when a bulk crystal is reduced to a monolayer 1-4 . Transition-metal oxide perovskites host a variety of correlated electronic phases 5-12 , so similar behaviour in monolayer materials based on transition-metal oxide perovskites would open the door to a rich spectrum of exotic 2D correlated phases that have not yet been explored. Here we report the fabrication of freestanding perovskite films with high crystalline quality almost down to a single unit cell. Using a recently developed method based on water-soluble Sr 3 Al 2 O 6 as the sacrificial buffer layer 13,14 we synthesize freestanding SrTiO 3 and BiFeO 3 ultrathin films by reactive molecular beam epitaxy and transfer them to diverse substrates, in particular crystalline silicon wafers and holey carbon films. We find that freestanding BiFeO 3 films exhibit unexpected and giant tetragonality and polarization when approaching the 2D limit. Our results demonstrate the absence of a critical thickness for stabilizing the crystalline order in the freestanding ultrathin oxide films. The ability to synthesize and transfer crystalline freestanding perovskite films without any thickness limitation onto any desired substrate creates opportunities for research into 2D correlated phases and interfacial phenomena that have not previously been technically possible.

Although it is commonly believed that the water-dissociation-related Volmer process is the rate-limiting step for alkaline hydrogen evolution reaction (HER) on Pt-based catalysts, the underlying essence, particularly on the atomic scale, still remains unclear. Herein, it is revealed that the sluggish water-dissociation behavior probably stems from unfavorable orbital orientation and the kinetic issue is successfully resolved via N-induced orbital tuning. Impressively, N modified Pt-Ni nanowires deliver an ultralow overpotential of 13 mV at 10 mA cm -2 , which represents a new benchmark for alkaline HER catalysis. Fine-structural characterization and density functional theory analysis illustrate that the introduced nitrogen can uniquely modulate the electron densities around the Ni sites, and further create empty d z 2 orbitals with superior orientation for water adsorption and activation. More importantly, it is demonstrated that N-induced orbital modulation can generally boost the alkaline HER activities of Pt-Co, Pt-Ni, and Pt-Cu, offering a new perspective for the design of HER catalysts and beyond., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Molybdenum disulfide is naturally inert for alkaline hydrogen evolution catalysis, due to its unfavorable water adsorption and dissociation feature originated from the unsuitable orbital orientation. Herein, we successfully endow molybdenum disulfide with exceptional alkaline hydrogen evolution capability by carbon-induced orbital modulation. The prepared carbon doped molybdenum disulfide displays an unprecedented overpotential of 45 mV at 10 mA cm -2 , which is substantially lower than 228 mV of the molybdenum disulfide and also represents the best alkaline hydrogen evolution catalytic activity among the ever-reported molybdenum disulfide catalysts. Fine structural analysis indicates the electronic and coordination structures of molybdenum disulfide have been significantly changed with carbon incorporation. Moreover, theoretical calculation further reveals carbon doping could create empty 2p orbitals perpendicular to the basal plane, enabling energetically favorable water adsorption and dissociation. The concept of orbital modulation could offer a unique approach for the rational design of hydrogen evolution catalysts and beyond.

Endowing materials with specific functions that are not readily available is always of great importance, but extremely challenging. Co 4 N, with its beneficial metallic characteristics, has been proved to be highly active for the oxidation of water, while it is notoriously poor for catalyzing the hydrogen evolution reaction (HER), because of its unfavorable d-band energy level. Herein, we successfully endow Co 4 N with prominent HER catalytic capability by tailoring the positions of the d-band center through transition-metal doping. The V-doped Co 4 N nanosheets display an overpotential of 37 mV at 10 mA cm -2 , which is substantially better than Co 4 N and even close to the benchmark Pt/C catalysts. XANES, UPS, and DFT calculations consistently reveal the enhanced performance is attributed to the downshift of the d-band center, which helps facilitate the H desorption. This concept could provide valuable insights into the design of other catalysts for HER and beyond., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Co/CoO nanoparticles immobilized on Co-N-doped carbon were successfully developed using shrimp-shell derived N-doped carbon nanodots as precursors by a combined approach of polymerization and pyrolysis, as electrocatalysts exhibiting trifunctional catalytic activities toward oxygen reduction, oxygen evolution and hydrogen evolution reactions and high performance in rechargeable zinc-air batteries.

Development of cheap, abundant and metal-free N-doped carbon materials as high efficiency oxygen reduction electrocatalysts is crucial for their practical applications in future fuel cell devices. Here, three-dimensional (3D) N-doped porous carbon (NPC) materials have been successfully developed by a simple template-assisted (e.g., SiO2 spheres) high temperature pyrolysis approach using shrimp-shell derived N-doped carbon nanodots (N-CNs) as carbon and nitrogen sources obtained through a facile hydrothermal method. The shrimp-shell derived N-CNs with a product yield of ∼ 5% possess rich surface O- and N-containing functional groups and small nanodot sizes of 1.5-5.0 nm, which are mixed with surface acidification treated SiO2 spheres with an average diameter of ∼ 200 nm in aqueous solution to form a N-CNs@SiO2 composite subjected to a thermal evaporation treatment. The resultant N-CNs@SiO2 composite is further thermally treated in a N2 atmosphere at different pyrolysis temperatures, followed by acid etching, to obtain 3D N-doped porous carbon (NPC) materials. As electrocatalysts for oxygen reduction reaction (ORR) in alkaline media, the experimental results demonstrate that 3D NPC obtained at 800 °C (NPC-800) with a surface area of 360.2 m(2) g(-1) exhibits the best ORR catalytic activity with an onset potential of -0.06 V, a half wave potential of -0.21 V and a large limiting current density of 5.3 mA cm(-2) (at -0.4 V, vs. Ag/AgCl) among all NPC materials investigated, comparable to that of the commercial Pt/C catalyst with an onset potential of -0.03 V, a half wave potential of -0.17 V and a limiting current density of 5.5 mA cm(-2) at -0.4 V. Such a 3D porous carbon ORR electrocatalyst also displays superior durability and high methanol tolerance in alkaline media, apparently better than the commercial Pt/C catalyst. The findings of this work would be valuable for the development of low-cost and abundant N-doped carbon materials from biomass as high performance metal-free electrocatalysts.