Turing Instability of Liquid-Solid Metal Systems.

The classical Turing morphogenesis often occurs in nonmetallic solution systems due to the sole competition of reaction and diffusion processes. Here, this work conceives that gallium (Ga) based liquid metals (LMs) possess the ability to alloy, diffuse, and react with a range of solid metals (SMs) and thus should display Turing instability leading to a variety of nonequilibrium spatial concentration patterns. This work discloses a general mechanism for obtaining labyrinths, stripes, and spots-like stationary Turing patterns in the LM-SM reaction-diffusion systems (GaX-Y), taking the gallium indium alloy and silver substrate (GaIn-Ag) system as a proof of concept. It is only when Ga atoms diffuse over Y much faster than X while X reacts with Y preferentially, that Turing instability occurs. In such a metallic system, Ga serves as an inhibitor and X as an activator. The dominant factors in tuning the patterning process include temperature and concentration. Intermetallic compounds contained in the Turing patterns and their competitive reactions have also been further clarified. This LM Turing instability mechanism opens many opportunities for constructing microstructure systems utilizing condensed matter to experimentally explore the general morphogenesis process.

Epitaxial van der Waals contacts of 2D TaSe2-WSe2 metal-semiconductor heterostructures.

The electronic contact between two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors and metal electrodes is a formidable challenge due to the undesired Schottky barrier, which severely limits the electrical performance of TMD devices and impedes the exploration of their unconventional physical properties and potential electronic applications. In this study, we report a two-step chemical vapor deposition (CVD) growth of 2D TaSe2-WSe2 metal-semiconductor heterostructures. Raman mapping confirms the precise spatial modulation of the as-grown 2D TaSe2-WSe2 heterostructures. Transmission electron microscopy (TEM) characterization reveals that this two-step method provides a high-quality and clean interface of the 2D TaSe2-WSe2 heterostructures. Meanwhile, the upper 1T-TaSe2 is formed heteroepitaxially on/around the pre-synthesized 2H-WSe2 monolayers, exhibiting an epitaxial relationship of (20-20)TaSe2//(20-20)WSe2 and [0001]TaSe2//[0001]WSe2. Furthermore, characterization studies using a Kelvin probe force microscope (KPFM) and electrical transport measurements present compelling evidence that the 2D metal-semiconductor heterostructures under investigation can improve the performance of electrical devices. These results bear substantial significance in augmenting the properties of field-effect transistors (FETs), leading to notable improvements in FET mobility and on/off ratio. Our study not only broadens the horizons of direct growth of high-quality 2D metal-semiconductor heterostructures but also sheds light on potential applications in future high-performance integrated circuits.

Defect-Mediated Growth of Crystallographic Shear Plane.

As representative extended planar defects, crystallographic shear (CS) planes, namely Wadsley defects, play an important role in modifying the physical and chemical properties of metal oxides. Although these special structures have been intensively investigated for high-rate anode materials and catalysts, it is still experimentally unclear how the CS planes form and propagate at the atomic scale. Here, the CS plane evolution in monoclinic WO3 is directly imaged via in situ scanning transmission electron microscope. It is found that the CS planes nucleate preferentially at the edge step defects and proceed by the cooperative migration of WO6 octahedrons along particular crystallographic orientations, passing through a series of intermediate states. The local reconstruction of atomic columns tends to form (102) CS planes featured with four edge-sharing octahedrons in preference to the (103) planes, which matches well with the theoretical calculations. Associated with the structure evolution, the sample undergoes a semiconductor-to-metal transition. In addition, the controlled growth of CS planes and V-shaped CS structures can be achieved by artificial defects for the first time. These findings enable an atomic-scale understanding of CS structure evolution dynamics.

Tailoring the microenvironment in Fe-N-C electrocatalysts for optimal oxygen reduction reaction performance.

Fe-N-C electrocatalysts, comprising FeN4 single atom sites immobilized on N-doped carbon supports, offer excellent activity in the oxygen reduction reaction (ORR), especially in alkaline solution. Herein, we report a simple synthetic strategy for improving the accessibility of FeN4 sites during ORR and simultaneously fine-tuning the microenvironment of FeN4 sites, thus enhancing the ORR activity. Our approach involved a simple one-step pyrolysis of a Fe-containing zeolitic imidazolate framework in the presence of NaCl, yielding a hierarchically porous Fe-N-C electrocatalyst containing tailored FeN4 sites with slightly elongated Fe-N bond distances and reduced Fe charge. The porous carbon structure improved mass transport during ORR, whilst the microenvironment optimized FeN4 sites benefitted the adsorption/desorption of ORR intermediates. Accordingly, the developed electrocatalyst, possessing a high FeN4 site density (9.9 × 1019 sites g-1) and turnover frequency (2.26 s-1), delivered remarkable ORR performance with a low overpotential (a half-wave potential of 0.90 V vs. reversible hydrogen electrode) in 0.1 mol L-1 KOH.

Epitaxial growth of structure-tunable ZnO/ZnS core/shell nanowire arrays using HfO2 as the buffer layer.

Synthesis of high-quality ZnO/ZnS heterostructures with tunable phase and controlled structures is in high demand due to their adjustable band gap and efficient electron-hole pair separation. In this report, for the first time, remote heteroepitaxy of single-crystalline ZnO/ZnS core/shell nanowire arrays has been realized using amorphous HfO2 as the buffer layer. Zinc blende or wurtzite ZnS epilayer can be efficiently fabricated under the same thermal deposition condition by adjusting the buffer layer thickness, even among the same batch of products, respectively. Structural characterization reveals "(01-10)ZnOwz//(2-20)ZnSZB, [0001]ZnOWZ//[001]ZnSZB" and "(01-10)ZnOWZ//(01-10)ZnSWZ, [0002]ZnOWZ//[0002]ZnSWZ" epitaxial relationships between the core and the shell, respectively. The cathodoluminescence measurement demonstrates that the tuning of the optical properties can be accomplished by preparing a heterostructure with HfO2, in which a strong green emission increases at the expense of the quenching of UV emission. In addition, the core/shell heterostructure based Schottky diode exhibits an asymmetrical rectifying behavior and an outstanding photo-electronic switching-effect. We believe that the aforementioned results could provide fundamental insights for epitaxial growth of structure-tunable ZnO/ZnS heterostructures on the nanoscale. Furthermore, this promising route buffered by the high-k material can broaden the options for fabricating heterojunctions and promote their application in photoelectric nanodevices.

Al2O3 buffer-facilitated epitaxial growth of high-quality ZnO/ZnS core/shell nanorod arrays.

II-VI semiconductor heterojunctions show huge potential for application in nanodevice fabrication due to their type-II alignments owing to the better spatial separation of electrons and holes. However, the hetero-epitaxial growth of high-quality heterostructures is still a challenge, especially for materials with large lattice mismatch. In this work, well-aligned single-crystalline ZnO/ZnS core/shell nanorod arrays were obtained by introducing an Al2O3 buffer layer. It is interesting that the nature of the ZnS layer varies with the thickness of the Al2O3 layer. When Al2O3 is less than 2 nm, the interaction between the substrate and epilayer is strong enough to penetrate through the buffer layer, enabling the growth of ZnS on Al2O3-coated ZnO nanorod arrays. On the basis of detailed characterization, a rational growth mechanism of the core/shell heterostructure is proposed, in which the Al2O3 interlayer can eliminate voids due to the Kirkendall effect around the interface and accommodate a misfit dislocation between the inner ZnO and outer ZnS, resulting in more sufficient strain relaxation in the epitaxy. In addition, cathodoluminescence measurements demonstrate that the optical properties of the ZnO/ZnS heterostructure could be effectively improved by taking advantage of the thin Al2O3. The I-V curves characterized by PeakForce tunneling atomic force microscopy reveal that the heterostructure shows a typical rectifying behavior and good photoresponse to ultraviolet light. These findings may provide a reasonable and effective strategy for the growth of highly lattice-mismatched heterostructure arrays buffered by the Al2O3 layer, broadening the options for fabricating heterojunctions and promoting their applications in optoelectronic devices.

Intra-Articular Platelet-Rich Plasma Combined With Hyaluronic Acid Injection for Knee Osteoarthritis Is Superior to Platelet-Rich Plasma or Hyaluronic Acid Alone in Inhibiting Inflammation and Improving Pain and Function.

PURPOSE: To evaluate the effectiveness and explore the therapeutic mechanisms of platelet-rich plasma (PRP) combined with hyaluronic acid (HA) as a treatment for knee osteoarthritis (KOA). METHODS: In total, 122 knees were randomly divided into HA (34 knees), PRP (40 knees), and PRP+HA (48 knees) groups. Platelet densities in whole blood and PRP were examined using Wright-Giemsa staining. Visual analogue scale, Lequesne, Western Ontario and McMaster Universities Osteoarthritis Index, Lysholm scores, and postoperative complications were evaluated. High-frequency color Doppler imaging was used to observe the synovium and cartilage. Enzyme-linked immunosorbent assays were used to quantify interleukin-1ß, tumor necrosis factor-α, matrix metalloproteinase-3, and tissue inhibitor of metalloproteinase-1 levels in synovial fluid. RESULTS: The platelet density in PRP was 5.13-times that in whole blood (P = .002). At 24 months, pain and function scores in the PRP+HA group were better than those in the HA-alone and PRP-alone groups (Ppain = .000; Pfunction = .000). At 6 and 12 months, synovial hyperplasia in the PRP and PRP+HA groups was improved (P < .05). After 6 and 12 months, the synovial peak systolic velocity, synovial end-diastolic velocity, systolic/diastolic ratio, and resistance index were improved in the PRP+HA group (P < .05). Complications were greatest in the PRP group (P = .008). After 6 and 12 months, interleukin-1ß, tumor necrosis factor-α, matrix metalloproteinase-3, and tissue inhibitor of metalloproteinase-1 in the PRP and PRP+HA groups decreased (P < .05), with more apparent inhibition in the PRP+HA group (P < .05). CONCLUSIONS: PRP combined with HA is more effective than PRP or HA alone at inhibiting synovial inflammation and can effectively improve pain and function and reduce adverse reactions. Its mechanism involves changes in the synovium and cytokine content. LEVEL OF EVIDENCE: Level II, Prospective cohort study.

Fabrication of multilayered electrospun poly(lactic-co-glycolic acid)/polyvinyl pyrrolidone + poly(ethylene oxide) scaffolds and biocompatibility evaluation.

Poly(lactic-co-glycolic acid)/polyvinyl pyrrolidone + poly(ethylene oxide) [PLGA/(PVP + PEO)] scaffolds with different polymer concentrations were fabricated using multilayered electrospinning, and their physicochemical properties and biocompatibility were examined to screen for scaffolds with excellent performance in tissue engineering (TE). PLGA solution (15% w/v) was used as the bottom solution, and a mixed solution of 12% w/v PVP + PEO was applied as the surface layer solution. The mass ratios of PVP vs. PEO in each 10 ml surface layer mixed solution were 1.08 g: 0.12 g; 0.96 g: 0.24 g; and 0.84 g: 0.36 g. Compared to the conventional electrospinning method used to fabricate the pure PVP + PEO (0.96 g: 0.24 g, Group A) scaffold and pure PLGA (Group E) scaffold, the multilayer electrospinning technique of alternating sprays of the bottom layer solution and the surface layer solution was adopted to fabricate multilayer nanofiber scaffolds, including PLGA/(PVP + PEO) (1.08 g: 0.12 g, Group B), PLGA/(PVP + PEO) (0.96 g: 0.24 g, Group C), and PLGA/(PVP + PEO) (0.84 g: 0.36 g, Group D). The morphology and characteristics of the five scaffolds were analyzed, and the biocompatibilities of the cell-scaffold composites were assessed through methods including Cell Counting Kit-8 (CCK8) analysis, 4',6-diamidino-2-phenylindole (DAPI) staining, and scanning electron microscopy. Therefore, with a PVP-to-PEO mass ratio of 0.96 g: 0.24 g, an optimal multilayer nanofiber scaffold was fabricated by the multilayer electrospinning technique. The excellent biocompatibility and mechanical properties of the scaffold were confirmed by in vitro experiments, which demonstrated the scaffold's promising application potential in the field of TE.

Osteoblastic differentiation of stem cells induced by graphene oxide-hydroxyapatite-alginate hydrogel composites and construction of tissue-engineered bone.

This study aimed to investigate the effect of graphene oxide (GO)-hydroxyapatite (HA)-sodium alginate (SA) composite application in the field of bone tissue engineering. Four scaffold groups were established (SA-HA, SA-HA-0.8%GO, SA-HA-1.0%GO and SA-HA-1.2%GO) and mixed with bone marrow mesenchymal stem cells (BMSCs). Hydrogel viscosity was measured at room temperature, and after freeze-drying and Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to detect substance crystallinity, the printability of each hydrogel type was measured with a printing grid. Scanning electron microscopy (SEM) was used to observe the internal microstructure of the scaffolds and to evaluate the growth and proliferation of cells on the scaffold. A hollow cylinder was printed to compare the forming effect of the hydrogel bioinks, and cell-hydrogel composites were implanted under the skin of nude mice to observe the effect of the hydrogels on osteogenesis in vivo. Increased GO concentrations led to reduced scaffold degradation rates, increased viscosity, increased printability, increased mechanical properties, increased scaffold porosity and increased cell proliferation rates. In vivo experiments showed that hematoxylin and eosin (HE) staining, Alizarin red staining, alkaline phosphatase staining and collagen type I immunohistochemical staining increased as the implantation time increased. These results demonstrate that GO composites have high printability as bioinks and can be used for bioprinting of bone by altering the ratio of the different components.

Deletion of TMEM268 inhibits growth of gastric cancer cells by downregulating the ITGB4 signaling pathway.

Transmembrane protein 268 (TMEM268) encodes a novel human protein of previously unknown function. This study analyzed the biological activities and molecular mechanisms of TMEM268 in vivo and in vitro. We found that TMEM268 deletion decreases cell viability, proliferation, and cell adhesion as well as causing S-phase cell cycle arrest and disrupts cytoskeleton remolding. Xenograft tumor mouse model studies showed that TMEM268 deletion inhibits the tumorigenesis of BGC823 gastric cancer cells. In addition, TMEM268-deleted BGC823 cells failed to colonize the lungs after intravenous injection and to form metastatic engraftment in the peritoneum. Molecular mechanism studies showed a C-terminal interaction between TMEM268 and integrin subunit ß4 (ITGB4). TMEM268 knockout promotes ITGB4 ubiquitin-mediated degradation, increasing the instability of ITGB4 and filamin A (FLNA). The reduced ITGB4 protein levels result in the disassociation of the ITGB4/PLEC complex and cytoskeleton remodeling. This study for the first time demonstrates that TMEM268 plays a positive role in the regulation of ITGB4 homeostasis. The above results may provide a new perspective that targeting the TMEM268/ITGB4 signaling axis for the treatment of gastric cancer, which deserves further investigation in the future.

Growth of vertical heterostructures based on orthorhombic SnSe/hexagonal In2Se3 for high-performance photodetectors.

Vertical heterostructures based on two-dimensional (2D) layered materials are ideal platforms for electronic structure engineering and novel device applications. However, most of the current heterostructures focus on layered crystals with a similar lattice. In addition, the heterostructures made by 2D materials with different structures are rarely investigated. In this study, we successfully fabricated vertical heterostructures by combining orthorhombic SnSe/hexagonal In2Se3 vertical heterostructures using a two-step physical vapor deposition (PVD) method. Structural characterization reveals that the heterostructures are formed of vertically stacked SnSe on the top of the In2Se3 film, and vertical heterostructures possess high quality, where In2Se3 exposed surface is the (0001) plane and SnSe prefers growing along the [100] direction. Raman maps confirm the precise spatial modulation of the as-grown SnSe/In2Se3 heterostructures. In addition, high-performance photodetectors based on the vertical heterostructures were fabricated directly on the substrate, which showed a broadband response, reversibility and stability. Compared with the dark current, the device demonstrated one order magnification of photocurrent, about 186 nA, under 405 nm laser illumination and power of 1.5 mW. Moreover, the device shows an obvious increase in the photocurrent intensity with the changing incident laser power, where I ph ∝ P 0.7. Also, the device demonstrated a high responsivity of up to 350 mA W-1 and a fast response time of about 139 ms. This study broadens the horizon for the synthesis and application of vertical heterostructures based on 2D layered materials with different structures and further develops exciting technologies beyond the reach of the existing materials.

Construction of an adherence rating scale for exercise therapy for patients with knee osteoarthritis.

BACKGROUND: Knee osteoarthritis (KOA) is one of the most common chronic diseases in the elderly and is the primary cause of the loss of motor function and disability in this population. Exercise therapy is a core, basic and matureand treatment method of treating patients with KOA. Exercise therapy is "strongly recommended" or "recommended" in the diagnosis and treatment guidelines of osteoarthritis in many countries, and most scholars advocate exercise therapy as the preferred rehabilitation method for KOA patients. However, poor long-term adherence is a serious problem affecting the therapeutic effect of this mature treatment. The objective of this study was to construct a concise and practical adherence rating scale (ARS) based on the exercise therapy adherence prediction model in patients with knee osteoarthritis. METHODS: A binary logistic regression model was established, with the adherence of 218 cases of KOA patients as the dependent variable. The patients' general information, exercise habits, knowledge, attitude, and exercise therapy were independent variables. The regression coefficients were assigned to various variables in the model, and the ARS was constructed accordingly. Receiver operating characteristic curves and curve fitting were used to analyse the effect of the ARS in predicting the adherence and to determine the goodness of fit for the adherence. The external validity of the ARS was examined in a randomized controlled trial. RESULTS: The construction of the adherence model and the ARS included the following variables: age (1 point), education level (1 point), degree of social support (2 points), exercise habits (3 points), knowledge of KOA prevention and treatment (2 points), degree of care needed to treat the disease (1 point), familiarity with exercise therapy (4 points) and treatment confidence (3 points). The critical value of the total score of the ARS was 6.50, with a sensitivity of 87.20% and a specificity of 76.34%. CONCLUSIONS: A KOA exercise therapy adherence model and a simple and practical ARS were constructed. The ARS has good internal validity and external validity and can be used to evaluate the adherence to exercise therapy in patients with KOA.

Layered SnSe nano-plates with excellent in-plane anisotropic properties of Raman spectrum and photo-response.

In-plane anisotropy in optical, electronic and thermal properties of two-dimensional (2D) materials has attracted significant interest because of the huge potential applications for developing novel devices. In this work, outstanding angle-dependent Raman property of layered SnSe nano-plates is obtained via polarized Raman system and it is confirmed that the Raman polarization directions of two Ag modes (130 cm-1 and 150 cm-1) are consistent with specific crystalline directions (zigzag direction or armchair direction) of SnSe flakes under parallel polarization configuration at home temperature and low temperature. Furthermore, the SnSe nano-plate devices show excellent angle-resolved photo-response at home temperature and low temperature (150 K) with a 90° cycle period and the polarized directions are also along zigzag direction and armchair direction, which is ascribed to the unique in-plane asymmetric crystal structure. These prominent in-plane anisotropic properties provide a precise and rapid method to determine the crystal orientation of SnSe nano-flakes and open up the new applications of 2D asymmetric structure materials.

van der Waals epitaxial two-dimensional CdSxSe(1-x) semiconductor alloys with tunable-composition and application to flexible optoelectronics.

Despite the substantial progress in the development of two-dimensional (2D) materials from conventional layered crystals, it still remains particularly challenging to produce high-quality 2D non-layered semiconductor alloys which may bring in some unique properties and new functions. In this work, the synthesis of well-oriented 2D non-layered CdSxSe(1-x) semiconductor alloy flakes with tunable compositions and optical properties is established. Structural analysis reveals that the 2D non-layered alloys follow an incommensurate van der Waals epitaxial growth pattern. Photoluminescence measurements show that the 2D alloys have composition-dependent direct bandgaps with the emission peak varying from 1.8 eV to 2.3 eV, coinciding well with the density functional theory calculations. Furthermore, photodetectors based on the CdSxSe(1-x) flakes exhibit a high photoresponsivity of 703 A W-1 with an external quantum efficiency of 1.94 × 103 and a response time of 39 ms. Flexible devices fabricated on a thin mica substrate display good mechanical stability upon repeated bending. This work suggests a facile and general method to produce high-quality 2D non-layered semiconductor alloys for next-generation optoelectronic devices.

van der Waals epitaxy and photoresponse of two-dimensional CdSe plates.

Here we demonstrate the first growth of two-dimensional (2D) single-crystalline CdSe plates on mica substrates via van der Waals epitaxy. The as-synthesized 2D plates exhibit hexagonal, truncated triangular and triangular shapes with the lateral size around several microns. Photodetectors based on 2D CdSe plates present a fast response time of 24 ms, revealing that 2D CdSe is a promising building block for ultrathin optoelectronic devices.

Physical vapor deposition synthesis of two-dimensional orthorhombic SnS flakes with strong angle/temperature-dependent Raman responses.

Anisotropic layered semiconductors have attracted significant interest due to the huge possibility of bringing new functionalities to thermoelectric, electronic and optoelectronic devices. Currently, most reports on anisotropy have concentrated on black phosphorus and ReS2, less effort has been contributed to other layered materials. In this work, two-dimensional (2D) orthorhombic SnS flakes on a large scale have been successfully synthesized via a simple physical vapor deposition method. Angle-dependent Raman spectroscopy indicated that the orthorhombic SnS flakes possess a strong anisotropic Raman response. Under a parallel-polarization configuration, the peak intensity of Ag (190.7 cm(-1)) Raman mode reaches the maximum when incident light polarization is parallel to the armchair direction of the 2D SnS flakes, which strongly suggests that the Ag (190.7 cm(-1)) mode can be used to determine the crystallographic orientation of the 2D SnS. In addition, temperature-dependent Raman characterization confirmed that the 2D SnS flakes have a higher sensitivity to temperature than graphene, MoS2 and black phosphorus. These results are useful for the future studies of the optical and thermal properties of 2D orthorhombic SnS.