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Stimuli-responsive materials that can be reversibly switched by light are of immense interest. Among them, photo-responsive spin crossover (SCO) complexes have great promises to combine the photoactive inputs with multifaceted outputs into switchable materials and devices. However, the reversible control the spin-state change by photochromic guests is still challenging. Herein, we report an unprecedented guest-driven light-induced spin change (GD-LISC) in a Hofmann-type metal-organic framework (MOF), [Fe(bpn){Ag(CN) 2 } 2 ]·azobenzene. ( 1 , bpn = 1,4-bis(4-pyridyl)naphthalene). The reversible trans-cis photoisomerization of azobenzene guest upon UV/vis irradiation in the solid state results in the remarkable magnetic changes in a wide temperature range of 10-180 K. This finding not only establishes a new switching mechanism for SCO complexes, but also paves the way toward the development of new generation of photo-responsive magnetic materials.

Conductive ionic hydrogel fibers and textiles with excellent mechanical properties and chemical stability are requested for flexible and wearable electronic devices, strain sensors, and even artificial skin. However, most of the reported hydrogel fibers are not suitable in complex environments, especially in alkaline solutions and organic solvents due to their poor chemical stability. Herein, we report ionic polyimide hydrogel fibers derived from an organosoluble polyimide salt that can be continuously and rapidly prepared via a facile wet spinning method. Thanks to their ion-rich property and robust skeletal structure, the obtained ionic polyimide hydrogel fibers showed an excellent conductivity of ∼21 mS/cm and outstanding mechanical properties with a tensile strength of 2.5 MPa and breaking elongation of 215%. Furthermore, the as-prepared fibers could be easily woven to form integral textiles, endowing them with good wearable properties. Accordingly, facile strain sensors assembled by polyimide hydrogel fibers show a linear response with high sensitivity and good cycling stability, which have great potential for applications in wearable and flexible strain sensors under diverse complex environments.

The pulling translocation of a polymer globule through a nanopore is simulated by using the Langevin dynamics method. The head of the polymer is pulled with a constant pulling force or with a constant pulling speed. The scaling relations between the polymer translocation time τ and polymer length N and between τ and the pulling force F/speed v are investigated. For translocation induced by a constant pulling force, we obtain τ ~F−β with β = 0.88 at large pulling forces and τ ~Nα for long polymer chains. However, the exponent α is dependent on the intrapolymer interaction strength. For the translocation induced by a constant pulling speed, we obtain τ ~v−0.92 at large pulling speeds and α = 1.24 for long polymer chains. The results show that the conformational changes of the polymer chain during translocation and the entropic and enthalpic forces due to the straight conformation at the trans side play important roles in the pulling translocation of polymer globules. Scaling relations of pulling translocation of a polymer globule through nanopores is studied by using the Langevin dynamics simulations. Under a constant pulling force, the scaling exponent is dependent on the intrapolymer interaction strength. Whereas under a constant pulling speed, it is independent of the intrapolymer interaction strength for sufficiently long polymer chains. The conformational changes of the polymer chain during the translocation and the entropic and enthalpic forces due to the straight conformation at the trans side play important roles on the pulling translocation of a polymer globule.

Polyaniline (PANI) is a promising cathode material for Zn-ion batteries (ZIBs) due to its intrinsic conductivity and redox activity; however, the achievements of PANI in high-performance ZIBs are largely hindered by its instability during the repeated charge/discharge. Taking advantage of the high conductivity, flexibility, and grafting ability together, a surface-engineered Ti3C2Tx MXene is designed as a silver bullet to fight against the deprotonation and swelling/shrinking issues occurring in the redox process of PANI, which are the origins of its instability. Specifically, the sulfonic-group-grafted Ti3C2Tx(S-Ti3C2Tx) continuously provides protons to improve the protonation degree of PANI and maintains the polymer backbone at a locally low pH, which effectively inhibits deprotonation and brings high redox activity along with good reversibility. Meanwhile, the conductive and flexible natures of S-Ti3C2Tx assist the fast redox reaction of PANI and concurrently buffer its corresponding swelling/shrinking. Therefore, the S-Ti3C2Tx-enhanced PANI cathode simultaneously achieves a high discharge capacity of 262 mAh g-1 at 0.5 A g-1, a superior rate capability of 160 mAh g-1 at 15 A g-1, and a good cyclability over 5000 cycles with 100% coulombic efficiency. This work enlightens the development of versatile MXene via surface engineering for advanced batteries.

In spinal cord injuries, external forces from various directions occur at various velocities. Therefore, it is important to physically evaluate whether the spinal cord is susceptible to damage and an increase in internal stress for external forces. We hypothesized that the spinal cord has mechanical features that vary under stress depending on the direction and velocity of injury. However, it is difficult to perform experiment because the spinal cord is very soft. There are no reports on the effects of multiple external forces. In this study, we used bovine spinal cord white matter to test and analyze the anisotropy and velocity dependence of the spinal cord. Tensile-vertical, tensile-parallel, shear-vertical, and shear-parallel tests were performed on the white matter in the fibrous direction (cranial to caudal). Strain rate in the experiment was 0.1, 1, 10, and 100/s. We calculated the Young's modulus of the spinal cord. Results of the tensile and shear tests revealed that stress tended to increase when external forces were applied parallel to the direction of axon fibers, such as in tensile-vertical and shear-vertical tests. However, external forces those tear against the fibrous direction and vertically, such as in tensile-parallel and shear-parallel tests, were less likely to increase stress even with increased velocity. We found that the spinal cord was prone to external forces, especially in the direction of the fibers, and to be under increased stress levels when the velocity of external forces increased. From these results, we confirmed that the spinal cord has velocity dependence and anisotropy. The Institutional Animal Care and Use Committee of Yamaguchi University waived the requirement for ethical approval.

An unprecedented A2MIMIIIX6-type double perovskite adopting a fully hexagonal BaNiO3-type structure, (piperidinium)2[KBiCl6], undergoes a 2/mF ferroelastic phase transition at 285 K with a spontaneous strain of 0.0615, arising from the order–disorder transition of organic cations together with the synchronous displacement of inorganic chains.

An efficient strategy (spontaneous deposition to enhance noble metal dispersity and core–shell confinement to inhibit noble metal sintering) is presented to synthesize active and thermally stable Ru/ZrO2 catalysts for dichloroethane combustion.

Lanthanide-doped ScF3 nanoparticles are synthesized and explored for thermal enhancement of upconversion. A hot-injection method is developed to control the formation of ScF3 nanoparticles with a c...

Multi-wavelength lasing, with dynamic switching functionality, high spectral purity and contrast, plays an essential role in photonic devices. Lanthanide(Ln3+)-doped upconversion nanocrystals(UCNCs) featured with plentiful energy levels act as ideal candidates for the gain medium. However, it remains a daunting challenge to develop a tunable Ln3+-based single-mode laser across a wide wavelength range due to the absence of an appropriate mode-selection mechanism. Here, we have demonstrated the first active control of unidirectional single-mode lasing with switchable wavelength spanning beyond a record range (~ 300 nm). This is accomplished through the integration of two size-mismatched coupled microdisks cavity and inversely designed dual-mode UCNCs incorporated with selective sensitizer-pair and activator ions. By asymmetric pumping, a reversible and crosstalk-free ultraviolet-to-red single-mode operation were formed respectively from such UCNCs-based system through changing the pumping wavelengths from 980 nm to 808 nm. The results enlighten the rational design of luminescent materials and microcavity. With remarkable doping flexibility, our approach would pave an avenue to a class of UCNCs-based photonic devices for on-chip optical filter, switch, sensor and other devices.

In situ glyco-editing on the cell surface can endow cellular glycoforms with new structures and properties; however, the lack of cell specificity and dependence on cells' endogenous functions plague the revelation of cellular glycan recognition properties and hamper the application of glyco-editing in complicated authentic biosystems. Herein, we develop a thermally triggered, cell-specific glyco-editing method for regulation of lectin recognition on target live cells in both single- and cocultured settings. The method relies on the aptamer-mediated anchoring of microgel-encapsulated neuraminidase on target cells and subsequent thermally triggered enzyme release for localized sialic acid (Sia) trimming. This temperature-based enzyme accessibility modulation strategy exempts genetic or metabolic engineering operations and, thus for the first time, enables tumor-specific desialylation on complicated tissue slices. The proposed method also provides an unprecedented opportunity to potentiate the innate immune response of natural killer cells toward target tumor cells through thermally triggered cell-specific desialylation, which paves the way for in vivo glycoimmune-checkpoint-targeted cancer therapeutic intervention.

Designing and synthesizing more advanced high-energetic materials for practical use via a simple synthetic route are two of the most important issues for the development of energetic materials. Through an elaborate design and rationally selected molecular components, two new metal-free hexagonal perovskite compounds, which are named as DAP-6 and DAP-7 with a general formula of (H2dabco)B(ClO4)3 (H2dabco2+ = 1,4-diazabicyclo[2.2.2]octane-1,4-diium), were fabricated via an easily scaled-up synthetic route using NH3OH+ and NH2NH3+ as B-site cations, respectively. Compared with their NH4+ analog ((H2dabco)(NH4)(ClO4)3; DAP-4), which has a cubic perovskite structure, DAP-6 and DAP-7 have higher crystal densities and enthalpies of formation, thus exhibiting higher calculated detonation performances. Specifically, DAP-7 has an ultrahigh thermal stability (decomposition temperatures (Td) = 375.3 °C), a high detonation velocity (D = 8.883 km·s−1), and a high detonation pressure (P = 35.8 GPa); therefore, it exhibits potential as a heat-resistant explosive. Similarly, DAP-6 has a high thermal stability (Td = 245.9 °C) and excellent detonation performance (D = 9.123 km·s−1, P = 38.1 GPa). Nevertheless, it also possesses a remarkably high detonation heat (Q = 6.35 kJ·g−1) and specific impulse (Isp = 265.3 s), which is superior to that of hexanitrohexaazaisowurtzitane (CL-20; Q = 6.23 kJ·g−1, Isp = 264.8 s). Thus, DAP-6 can serve as a promising high-performance energetic material for practical use.

As appropriate alternatives to precious metals in volatile organic compound (VOC) combustion, La-based perovskites have attracted increasing attention due to their tunable structure and sintering-r...

Gas therapy has emerged as a forceful strategy for augmenting the effects of chemotherapeutic drugs against cancer cells. However, it remains extremely challenging to effectively deliver gas into tissues of interest and unravel its underlying mechanisms. Herein, we designed a near-infrared (NIR) light-switchable nitric oxide (NO) delivery nanosystem for high-efficacy multidrug resistance (MDR) reversal in cancer therapy based on a yolk-shell upconverting nanoparticles@magnesium silica (UCNP@MgSiO3). The internal hollow cavity and flower-like mesoporous shell of UCNPs@MgSiO3 not only enabled a significantly high encapsulation capacity for the NO precursor (BNN6) and doxorubicin (DOX) but also allowed the enhanced cellular uptake, resulting in NIR-triggered NO generation and low pH-triggered DOX release in cancer cells. Mechanistically, intracellular NO can downregulate the drug efflux-related P-glycoprotein and adenosine 5'-triphosphate-binding cassette transporters, thereby increasing the DOX accumulation in the cell nuclei. Such combination therapy of NO and DOX induced the apoptosis of MDR cells and completely inhibited in vivo MDR tumor growth. We further elucidated the therapy mechanism via proteomic profiling, showcasing the downregulation of the ubiquitin-proteasome pathway and nuclear factor kappa-B signaling pathway in the NO-treated MDR cells. Therefore, our findings develop a promising nanoscale gas/drug delivery paradigm for fighting MDR tumors and providing molecular insights into cancer therapy.

Both the mechanical properties and microstructure of die-casting ADC12 + x(La+Yb) alloy (x = 0, 0.3 wt.%, 0.6 wt.%, 0.9 wt.%) were investigated. It was found that the main compounds of the ADC12 ma...

We present a new hybrid compound, namely (Me2NH2)[KFe(CN)5(NO)], possessing a unique nitroprusside-based inorganic host framework in 4-connected sra topology encapsulating organic guest cations. The flexible host-guest hydrogen bonds and synchronously deformed inorganic framework give rise to thermal-responsive switching behaviours on both thermal expansion and nonlinear optical properties during the phase transition at around room temperature.

Core-shell structural engineering is a common strategy for tuning upconversion luminescence in lanthanide-doped nanoparticles. However, epitaxial growth on hexagonal phase NaYbF4 nanoparticles typically suffers from incomplete shell coverage due to the large and anisotropic interfacial strain. Herein, we explore the effects of core particle size and morphology as well as reaction temperature on controlling the epitaxial growth of NaGdF4 shells on NaYbF4 nanoparticles with misfit parameters of fa = 1.58% and fl = 2.24% for axial and lateral growth, respectively. Rod-like core particles with a long length and a large diameter are found to promote shell growth with high surface coverage by facilitating the relaxation of lattice strains. Furthermore, the primary NaGdF4 shell can serve as a transition layer to mediate the growth of additional NaNdF4 coating layers that display an even larger lattice misfit with the core (fa = 2.98%; fl = 4.32%). The resultant NaYbF4@Na(Gd/Nd)F4 core-shell nanostructures simultaneously show strong multiphoton upconversion luminescence and superior magnetic resonance T1 ionic relaxivity. Our findings are important for the rational design of core-shell upconversion nanoparticles with optimized properties and functionality for technological applications.

The simultaneous shaping and confinement of Cu-based MOP in alginate-SiO2 spheres significantly enhance the mechanical strength and leaching resistance of Cu-MOP. The resulting MOP-alginate-SiO2 is shown through chemical fixation of CO2 to exhibit improved product yield over the parent Cu-MOP and Cu-alginate-SiO2.

Antimony (Sb) based materials are regarded as promising anode materials for Li-ion batteries (LIBs) because of the high capacity, appropriate working potential, and earth abundance of antimony. However, the quick capacity decay due to the huge volume expansion during the cycling process seriously hinders its practical applications. Here, a nanocomposite of core@shell Sb@Sb2O3 particles anchored on 3D porous nitrogen-doped carbon (3DNC) nanosheets is synthesized by freeze drying and sintering in a reducing atmosphere. Structural characterization shows that the developed Sb@Sb2O3/3DNC electrode has a high surface area (839.8 m2 g−1) and unique Sb–O–C bonding, both contributing to the excellent electrochemical performance. The initial charge and discharge specific capacities of the Sb@ Sb2O3/3DNC anode in LIB tests are 1109 mA h g−1 and 1810 mA h g−1, respectively. Also, it shows a charge capacity of 696.9 mA h g−1 after 500 cycles at 1 A g−1 and 458 mA h g−1 at a current density of 5 A g−1. Moreover, the assembled Sb@Sb2O3/3DNC‖LiNi0.6Co0.2Mn0.2O2 battery exhibits a discharge capacity of more than 100 mA h g−1 after 25 cycles at 100 mA g−1. The synthetic method can be extended to obtain other nanocomposites of metal and carbon materials for high-performance energy storage devices.

Lithium–sulfur (Li–S) battery is identified as one of the most promising next‐generation energy storage systems due to its ultra‐high theoretical energy density up to 2600 Wh kg−1. However, Li metal anode suffers from dramatic volume change during cycling, continuous corrosion by polysulfide electrolyte, and dendrite formation, rendering limited cycling lifespan. Considering Li metal anode as a double‐edged sword that contributes to ultrahigh energy density as well as limited cycling lifespan, it is necessary to evaluate Li‐based alloy as anode materials to substitute Li metal for high‐performance Li–S batteries. In this contribution, the authors systematically evaluate the potential and feasibility of using Li metal or Li‐based alloys to construct Li–S batteries with an actual energy density of 500 Wh kg−1. A quantitative analysis method is proposed by evaluating the required amount of electrolyte for a targeted energy density. Based on a three‐level (ideal material level, practical electrode level, and pouch cell level) analysis, highly lithiated lithium–magnesium (Li–Mg) alloy is capable to achieve 500 Wh kg−1 Li–S batteries besides Li metal. Accordingly, research on Li–Mg and other Li‐based alloys are reviewed to inspire a promising pathway to realize high‐energy‐density and long‐cycling Li–S batteries.

Switching materials in channels of nonlinear optics (NLOs) are of particular interest in NLO material science. Numerous crystalline NLO switches based on structural phase transition have emerged, but most of them reveal a single-step switch between two different second-harmonic-generation (SHG) states, and only very rare cases involve three or more SHG states. Herein, we report a new organic-inorganic hybrid salt, (Me3 NNH2 )2 [CdI4 ], which is an unprecedented case of a reversible three-step NLO switch between SHG-silent, -medium, -low, and -high states, with high contrasts of 25.5/4.3/9.2 in a temperature range of 213-303 K. By using the combined techniques of variable-temperature X-ray single-crystal structural analyses, dielectric constants, solid-state 13 C nuclear magnetic resonance spectroscopy, and Hirshfeld surface analyses, we disclose that this four-state switchable SHG behavior is highly associated with the stepwise-changed molecular dynamics of the polar organic cations. This finding demonstrates well the complexity of molecular dynamics in simple hybrid salts and their potential in designing new advanced multistep switching materials.

Smartphone-enabled microfluidic chemiluminescence immunoassay is a promising portable system for point-of-care (POC) biosensing applications. However, due to the rather faint emitted light in such a limited sample volume, it is still difficult to reach the clinically accepted range when the smartphone serves as a standalone detector. Besides, the multiple separation and washing steps during sample preparation hinder the immunoassay's applications for POC usage. Herein, we proposed a novel acoustic streaming tweezers-enabled microfluidic immunoassay, where the probe particles' purification, reaction, and sensing were simply achieved on the same chip at continuous-flow conditions. The dedicatedly designed high-speed microscale vortexes not only enable dynamic trapping and washing of the probe particles on-demand but also enhance the capture efficiency of the heterogeneous particle-based immunoassay through active mixing during trapping. The enriched probe particles and enhanced biomarker capture capability increase the local chemiluminescent light intensity and enable direct capture of the immunobinding signal by a regular smartphone camera. The system was tested for prostate-specific antigen (PSA) sensing both in buffer and serum, where a limit of detection of 0.2 ng/mL and a large dynamic response range from 0.3 to 10 ng/mL using only 10 μL of sample were achieved in a total assay time of less than 15 min. With the advantages of on-chip integration of sample preparation and detection and high sensing performance, the developed POC platform could be applied for many on-site diagnosis applications.

Photon frequency conversion using optical materials is a common strategy for light generation and utilization. Materials capable of visible‐to‐ultraviolet (UV) light conversion have attracted particular attention due to their potential applications in nonlinear optics, biophotonics, as well as environmental sciences. There are four main mechanisms of visible‐to‐UV light conversion processes, including second‐harmonic generation, two‐photon absorption, lanthanide‐based upconversion, and triplet–triplet annihilation. Herein, recent developments in visible‐to‐UV light conversion materials are collectively reviewed and the emerging applications are presented. The prospects and challenges for further development in this field are also highlighted.

Shape memory alloy undergoing reversible martensitic transformation is an important class of metallic functional materials. In the past two decades, the development of shape memory alloys enables great advances in biomedical devices, microelectronics, and energy conversions. As the application scales of these devices get smaller and smaller, it is very critical to understand and tune the mechanical properties of shape memory alloys in nanoscale regime. While there are extensive reviews of shape memory alloys regarding their macroscopic properties, metallurgical treatments, and applications in the design of microdevices, their nanomechanics are not well summarized and thoroughly compared transversely among different experimental setups. This review provides an insight of the latest discoveries in nanomechanics of NiTi-based and Cu-based shape memory alloys, which sorts out the size effects, the deformation mechanisms, and the functional fatigue of the miniaturized samples in single-crystalline and polycrystalline formats.

Ag@ZnS nanoparticles display enhanced photocatalytic efficiency and good photoelectric properties compared to their single-component counterparts in the process of forming a core-shell structure using an Ag cluster as the inner core of a ZnS outer shell. In this study, first-principles calculations were used to investigate the structural, electronic, and optical properties of Agn@(ZnS)42 (n = 6-16) core-shell nanocomposites. The calculated results show significant even-odd oscillations in the structural stability, that is, Ag@ZnS nanostructures with an even number of Agn core atoms are relatively more stable than those with an odd number of core atoms. The second-order differences in the total energies (Δ2E) and the core-shell interaction energy Ecs indicate that a Ag12@(ZnS)42 nanostructure is the most stable configuration. A significant red shift was found in Agn@(ZnS)42 nanoparticles in the absorption spectrum compared with a (ZnS)48 nanostructure, which is likely attributed to the strong electron interactions between the Ag core and the ZnS shell. Keywords: Core-shell structure, DFT, Optical properties, Red shift phenomenon, Electronic structure

Ferroelectricity is usually found in cubic and hexagonal perovskites consisting of corner- and faced-shared BX6 octahedra, respectively. In contrast, another important branch of perovskites, postpe...

An amorphous ZrO2 mesoporous material was prepared by propylene oxide (PO)-assisted sol-gel process and was first evaluated in CH4 oxychlorination. Various characterizations were conducted including XRD, N2 adsorption–desorption, NH3-TPD, CO2-TPD, SEM, and TEM. Results showed the amorphous ZrO2 with mesoporosity and large SSA exhibited abundant surface acid and base sites. As a non-redox catalyst, the amorphous ZrO2 unexpectedly delivered much higher activity and better stability in CH4 oxychlorination than conventional ZrO2. The CH4 conversion was 18.6% and the selectivity of CH3Cl and CO reached 47.6% and 30.2% at 490 °C, respectively. The amorphous ZrO2 could stably operate at 470 °C for 50 h without significant deactivation. Kinetic studies revealed that the CH4 activation on the surface of the amorphous ZrO2 was the rate-determining step.

Polyethylenimine (PEI) impregnated MCM-48 samples without calcination (MCM-48-W) whose pores are covered with cetyltrimethylammonium bromide (CTAB with long-alkyl chains) were verified to be more e...

Understanding the phonon transport in thermoelectric materials and its coupling with the complex environments is critical for manipulating the lattice thermal conductivity and consequently creating a high heat-to-electricity conversion efficiency. Spin-orbit coupling, an elementary interaction usually neglected when calculating lattice thermal conductivity, is intuitively expected to affect only the harmonic phonon properties in the materials. We herein studied the phonon transport in SnSe, a thermoelectric material with record-high energy conversion efficiency, by first-principle calculation and the Boltzmann transport equation. Spin-orbit coupling is found to greatly enhance its lattice thermal conductivity (up to ∼60%). More surprisingly, this enhancement originates from the influence of spin-orbit coupling on the phonon anharmonicity instead of the harmonic phonon properties. Spin-orbit coupling reduces the delocalization of the resonant bonding network formed by the p-orbitals of Se atoms, strengthens the interlayer Sn-Se bonds and consequently weakens the phonon anharmonicity. This discovery should encourage the design of tunable spin-orbit systems for better manipulation of thermoelectricity as well as other phonon transport related material functions.

The order phase in FeNiCoCr medium-entropy alloys has been investigated in experiments. Using ab initio calculations, we find the transformation from the disordered face centered cubic solid solution to the ordered L12 structure has an important effect on the magnetic-elastic properties of equimolar FeNiCoCr medium-entropy alloy. As a function of order degree x in the pseudobinary Crx(FeNiCo)(1-x)/3 alloy, the increasing magnetic moment of Cr is responsible for the increase of shear moduli c’ and c44, whereas the decrease of total magnetic moment induces increase of tensile modulus c11. The ordering reduces the elastic anisotropy and intrinsic ductility of FeNiCoCr.

We demonstrate a simple and direct method to precisely characterize the optical beam shear angle of polarizing prisms. Applying nanometer localization analysis for determining the central positions of the two sheared spots with orthogonal polarizations, we show that it allows for resolving the shear angle beyond the optical diffraction limit. We use Nomarski prisms to verify our technique and obtain a resolution below 0.5 μ rad. Our method provides a stand-alone characterization of polarizing prisms with a high accuracy for many quantitative imaging technologies such as differential interference contrast microscopy.

We theorize a mathematical model by which the topography and the full-field deformation of martensitic microstructure are quantitatively determined by the reflected light differential interference contrast microscopy technique. Using the commercial reflected light DIC microscope (Nikon Ni-U), we determine the optical parameters for the proposed mathematical model using calibrated standard samples. Based on the theory, we conduct an experiment to demonstrate the determination of the surface relief of the microstructure comprised of a pair of twinned martensitic variants. The surface height gradients of the two martensite variants along the beam-shear direction of DIC agree well with the values measured by the atomic force microscopy. The measured results of twin laminates reveal that the current microscopy system can resolve the microstructure with the fineness of around 500 nm. Compared with the AFM results, it measures the surface slope with 0.005 rad accuracy. This paper underlies a new approach for quantitative surface topography determination with wide applications in experimental mechanics.

Effective bone tissue engineering can restore bone and skeletal functions that are impaired by traumas and/or certain medical conditions. Bone is a complex tissue and functions through orchestrated interactions between cells, biomechanical forces, and biofactors. To identify ideal scaffold materials for effective mesenchymal stem cell (MSC)-based bone tissue regeneration, here we develop and characterize a composite nanoparticle hydrogel by combining carboxymethyl chitosan (CMCh) and amorphous calcium phosphate (ACP) (designated as CMCh-ACP hydrogel). We demonstrate that the CMCh-ACP hydrogel is readily prepared by incorporating glucono δ-lactone (GDL) into an aqueous dispersion or rehydrating the acidic freeze-dried nanoparticles in a pH-triggered controlled-assembly fashion. The CMCh-ACP hydrogel exhibits excellent biocompatibility and effectively supports MSC proliferation and cell adhesion. Moreover, while augmenting BMP9-induced osteogenic differentiation, the CMCh-ACP hydrogel itself is osteoinductive and induces the expression of osteoblastic regulators and bone markers in MSCs in vitro. The CMCh-ACP scaffold markedly enhances the efficiency and maturity of BMP9-induced bone formation in vivo, while suppressing bone resorption occurred in long-term ectopic osteogenesis. Thus, these results suggest that the pH-responsive self-assembled CMCh-ACP injectable and bioprintable hydrogel may be further exploited as a novel scaffold for osteoprogenitor-cell-based bone tissue regeneration.

Ti3C2T x (MXene) exhibits attractive properties in different applications. However, traditional synthesis leads to unsatisfactory yield of two-dimensional (2D) Ti3C2T x, e.g., lower than 20%, which stems from the strong interactions of potential Ti-Ti bonds and residual Ti-Al bonds between the adjacent Ti3C2 layers, hindering the effective intercalation and delamination. Herein, we propose a facile hydrothermal-assisted intercalation (HAI) strategy to boost the yield of 2D sheets, achieving a record high value of 74%. This HAI assists the diffusion and intercalation of reagent effectively, promoting the subsequent delamination; meanwhile, an antioxidant is applied to protect these Ti3C2T x from oxidation during the HAI process. Therefore, massive Ti3C2T x 2D sheets can be easily synthesized. Thanks to the synergistic effect of high conductivity and substantial terminated functionalities, these Ti3C2T x 2D sheets show promising application in supercapacitor, providing a high capacitance of 482 F g-1. Besides, the ultrafast carrier dynamics results of Ti3C2T x 2D sheets clearly imply the promising application in photocatalysis due to the relatively long bleaching relaxation time. Our work not only paves the way for the mass production of Ti3C2T x 2D sheets but also provides insights into their electronic and optical properties.

We presented two new ABX3 postperovskite coordination polymers, (C5H13NCl)[M(dca)3] (dca = N(CN)2–, M = Mn2+ for 1 and Cd2+ for 2), as well as their phase transition behaviors disclosed by using differential scanning calorimetry measurements, variable-temperature single-crystal X-ray analyses, dielectric measurements, and Hirshfeld surface analyses. Both 1 and 2 have same structure (Cmcm) at room temperature, in which their A-site organic cations are fourfold disordered about two mirror planes and undergo order–disorder phase transition mainly caused by the freezing of A-site cations upon cooling. The different metal ions endow them distinct structural flexibility, resulting in different phase transition behaviors and dielectric responses; that is, the smaller and coordinatively rigid Mn2+ ion results in two-step Cmcm (Z = 4) ↔ Pbcm (Z = 4) ↔ Pbca (Z = 8) transitions accompanied with obvious dielectric relaxation, whereas the larger and coordinatively flexible Cd2+ ion results in one-step Cmcm (Z = 4) ↔ P...

A series of Ce-Ti mixed oxides (CeaTi1−a) were successfully synthesized by a spontaneous deposition method and evaluated in selective catalytic reduction of NO with NH3 (NH3-SCR). The structures and properties of the CeaTi1−a catalysts were characterized by means of XRD, Raman, TEM, N2-sorption, XPS, H2-TPR and NH3-TPD. The results demonstrated that lots of Ce-O-Ti species were formed because of the strong synergistic interaction of gelation of TiO2 and deposition of Ce3+ during the preparation process of CeaTi1−a catalysts. As results, the CeaTi1−a catalysts exhibited excellent redox ability, enrichment of Ce3+ species, high surface adsorbed oxygen concentration, and abundant acid sites. The CeaTi1−a catalysts showed remarkable catalytic activity with broad operation temperature window, and Ce0.5Ti0.5 catalyst exhibited the best catalytic activity and extraordinary H2O/SO2 durability. The in-situ FTIR results revealed that the mechanisms of L-H and E-R existed synchronously during the NH3-SCR reaction, and the former one was predominant due to its rapid reaction rate.

We propose a scheme for assigning the martensite variant using electron backscatter diffraction in a martensite material that undergoes a solid–solid phase transformation. Based on the solutions of the crystallographic equations of martensite, we provide an algorithm to assign martensite variants to a particular microscopic region, and to check the elastic compatibility of the microstructure corresponding to low hysteresis and high reversibility in shape memory alloys. This article is part of the theme issue ‘Topics in mathematical design of complex materials’.

The effect of the loading of nanoparticles on the glass transition temperature, Tg, of polymer nanocomposites is studied by using molecular dynamics simulations. Tg is estimated from the variation of system volume with temperature and the temperature-dependent diffusion of the polymer described by the Vogel-Fulcher-Tammann law. The estimated values of Tg from the two methods are consistent with each other. Results show that Tg can be regulated by changing the volume fraction of nanoparticles, fNP. A novel shift in Tg is observed, that is, Tg increases with fNP at fNP, while it decreases with increasing fNP at fNP. The basic mechanism behind the novel shift in Tg is the competition between the attraction of nanoparticles towards polymer chains and the fast diffusion of nanoparticles. The increase in Tg at low fNP is due to the attraction of nanoparticles, whereas the decrease in Tg at high fNP is attributed to the fast diffusion of nanoparticles. The diffusion of the polymer above Tg is also investigated. The diffusion of the polymer decreases with increasing fNP below and increases with fNP above , in agreement with the variation of Tg.

The coexistence of multiferroic orders has attracted increasing attention for its potential applications in multiple-state memory, switches, and computing, but it is still challenging to design single-phase crystalline materials hosting multiferroic orders at above room temperature. By utilizing versatile ABX3-type perovskites as a structural model, we judiciously introduced a polar organic cation with easily changeable conformations into a tetrafluoroborate-based perovskite system, and successfully obtained an unprecedented molecular perovskite, (homopiperazine-1,4-diium)[K(BF4)3], hosting both ferroelectricity and ferroelasticity at above room temperature. By using the combined techniques of variable-temperature single-crystal X-ray structural analyses, differential scanning calorimetry, and dielectric, second harmonic generation, and piezoresponse force microscopy measurements, we demonstrated the domain structures for ferroelectric and ferroelastic orders, and furthermore disclosed how the delicate interplay between stepwise changed dynamics of organic cations and cooperative deformation of the inorganic framework induces ferroelectric and ferroelastic phase transitions at 311 K and 455 K, respectively. This instance, together with the underlying mechanism of ferroic transitions, provides important clues for designing advanced multiferroic materials based on organic–inorganic hybrid crystals., An unprecedented tetrafluoroborate-based perovskite reveals the coexistence of ferroelastic and ferroelectric transitions arising from delicate interplay between stepwise frozen organic cations and cooperative deformation of the framework.

Fluorescent probes have attracted special attention in developing optical sensor systems due to their reliable and rapid fluorescent response upon reaction with the analyte. Comparing to traditional fluorescent sensing systems that employ the intensity of only a single emission, ratiometric fluorescent sensors exhibit higher sensitivity and allow fast visual screening of analytes because of quantitatively analyzing analytes through the emission intensity ratio at two or more wavelengths. Lanthanide metal–organic frameworks (LnMOFs) are highly designable multifunctional luminescent materials as lanthanide ions, organic ligands, and guest metal ions or chromophores are all potential sources for luminescence. They thus have been widely employed as ratiometric fluorescent sensors. This mini review summarized the basic concept, optical features, construction strategies, and the ratiometric fluorescent sensing mechanisms of dual-emitting LnMOFs. The review ends with a discussion on the prospects, challenges, and new direction in designing LnMOF-based ratiometric fluorescent sensors.

Cyclooxygenase-2 (COX-2) is an important rate-limiting enzyme in the synthesis of prostaglandins (PGs), which can be upregulated by various stimuli. COX-2 has been shown to be involved in the occurrence and development of hepatic fibrosis by regulating the proliferation and apoptosis of hepatic stellate cells (HSCs) in previous studies. The aims of the study are to study the mechanism of how COX-2 regulates the proliferation and apoptosis of HSCs and to provide new targets for the prevention and treatment of hepatic fibrosis. A short hairpin RNA targeting COX-2 was constructed, and the changes in proliferation and apoptosis of liver tissue cells and HSCs were observed, respectively. COX-2-shRNA-1 significantly suppressed the proliferation of HSCs in vivo. Moreover, knockdown of COX-2 significantly suppressed cell proliferation and accelerated cell cycle arrest and apoptosis in vitro. Among those differential genes related to cell proliferation and apoptosis, CDC27 and Sh3kbp1 were upregulated, but Plcd4 was suppressed. Mechanistically, the influence of COX-2 on HSCs partly depends on upregulating CDC27. Our results demonstrated that COX-2 regulates the proliferation and apoptosis of activated hepatic stellate cells through the CDC27 pathway. This study contributes to our understanding of the effect of COX-2 for the treatment of hepatic fibrosis.

Both crystallographic compatibility and grain engineering are super critical to the functionality of shape memory alloys, especially at micro- and nanoscales. Here, we report a bicrystal CuAl24Mn9 micropillar engraved at a high-angle grain boundary (GB) that exhibits enhanced reversibility under very demanding driving stress (about 600 MPa) over 10 000 transformation cycles despite its lattice parameters are far from satisfying any crystallographic compatibility conditions. We propose a new compatibility criterion regarding the GB for textured shape memory alloys, which suggests that the formation of GB compatible twin laminates in neighboring textured grains activates an interlock mechanism, which prevents dislocations from slipping across GB.

The near equiatomic NiTi alloy is the most successful shape memory alloy by a large margin. It is widely and increasingly used in biomedical devices. Yet, despite having a repeatable superelastic effect and excellent shape-memory, NiTi is very far from satisfying the conditions that characterize the most reversible phase-transforming materials. Thus, the scientific reasons underlying its vast success present an enigma. In this paper, we perform rigorous mathematical derivations and accurate density-functional theory calculations of transformation mechanisms to seek previously unrecognized twinlike defects that we term involution domains, and we observe them in real space in NiTi by aberration-corrected scanning transmission electron microscopy. Involution domains lead to an additional 216 compatible interfaces between phases in NiTi, and we theorize that this feature contributes importantly to its reliability. They are expected to arise in other transformations and to alter the conventional interpretation of the mechanism of the martensitic transformation.