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Efficient removal of pollutant formaldehyde (HCHO) at room temperature using transition-metal oxides remains a huge challenge to date. Manganese oxide can oxidize formaldehyde, however, how to control the valence states of manganese is the key to further improve the removal efficiency. We have successfully prepared porous manganese oxide nanowires (MnOx NWs) with large surface area and multiple valence states of manganese using simple electrospinning followed by thermal calcination and potassium permanganate solution post-treatment (C/S process). The contents of trivalent and tetravalent manganese increased significantly after C/S process. Moreover, the composition of silver oxide coated silver nanowires (Ag@Ag2O NWs) is realized by assistance with oxygen plasma, which further enhanced high valence manganese. The formaldehyde removal efficiency by Ag@Ag2O–MnOx composite nanowires can reach 93.7%. The high-efficient catalytic activity is confirmed to attribute to the higher surface area of composite nanowires, the high-valence manganese and the silver oxide for oxidation of formaldehyde.

To expand the future clinic applications of biodegradable magnesium alloy, polymer coatings with excellent biocompatibility are the keys to solve the local alkalinity and rapid hydrogen release. Natural−organic silk fibroin provides an approach to fabricate a protective coating on biomedical Mg−Zn−Ca alloy, however, the adhesion force and mechanical properties of the coating on substrates are ought to be further improved without any chemical conversion/intermediate layer. Hereby, based on VUV/O3 surface activation, a hybrid of silk fibroin and sodium alginate is proposed to enhance the adhesion force and mechanical properties of the composite coatings on hydrophilic Mg−Zn−Ca alloy surfaces. Various mass ratios of sodium alginate addition were investigated to achieve the optimum coating strategy. The nanoscratch test and nanoindentation test confirmed that the adhesion force was tripled and mechanical properties index was significantly improved when the mass ratio of silk fibroin/sodium alginate was 70/30 compared to pure silk fibroin or sodium alginate coatings. Meanwhile, the corrosion rate of the coated Mg−Zn−Ca alloy was significantly delayed with the addition of sodium alginate, resulting in a reaction layer during corrosion process. Furthermore, the mechanisms for both adhesion and corrosion processes were discussed in detail. Our findings offer more possibilities for the controllable surface performance of degradable metals.

In the present work, a high quality (Q) Ca1.15Sm0.85Al0.85Ti0.15O4 (CSAT) ceramic was prepared via reaction sintering (RS) method. The phase structure, surface morphology, packing fraction (PF), and valence bond of the ceramic were systematically investigated. By studying the X-ray diffraction (XRD) pattern of the ceramic, it was determined to exhibit a single-phase tetragonal structure with the dimensions of a = b = 3.6943(13)A and c = 12.0320(23)A and volume of V = 164.22(10) A3. The influence of the intrinsic quality loss factor on the Q × f value was investigated by calculating the PF. Simultaneously, the bond valence of the samarium (Sm) sites was evaluated to elucidate the relationship with the temperature coefficient of resonant frequency (τf). The CSAT ceramic was sintered at 1550 °C for 6 h and exhibited exceptional characteristics in terms of the relative dielectric constant (er) = 17.5, quality factor (Q × f) = 66700 GHz, and τf = −6.93 ppm/°C. These results highlighted the excellent suitability of the RS method for preparing CSAT ceramics with outstanding microwave dielectric properties.

0.85(0.74CaTiO3–0.26SmAlO3)–0.15Ca1.15Sm0.85Al0.85Ti0.15O4 (CSC) composite ceramics were prepared by a reaction-sintering method. The phase structure, sintering behavior and microwave dielectric properties of CSC ceramics were investigated. The preparation process of reaction-sintering route (RS) is simple. XRD patterns show that Ca0.74Ti0.74Sm0.26Al0.26O3 (similar to CaTiO3), SmAlO3 and Ca1.15Sm0.85Al0.85Ti0.15O4 phases are formed in the CSC ceramics. The grain size and dielectric constant of CSC ceramics increase with rising the sintering temperature. As the sintering temperature increases, the quality factor (Q × f) and τf value of the CSC ceramics increase to the maximum values first and then decrease. The bulk density fluctuates up and down around a value, but little change. The ceramics sintered at 1500 °C got the best microwave dielectric performances with er = 35.9, Q × f = 49,221 GHz, τf = − 0.53 ppm/°C.

A novel La2MgGeO6 ceramic was synthesized through a solid-state reaction process within a sintering temperature range of 1450–1550 °C. By a combination of X-ray diffraction and Rietveld refinement analyses, the ceramics were found to have a pure hexagonal phase structure belonging to space group R3/146. The scanning electron microscopy images revealed that the ceramic grains were closely connected. The effects of internal (lattice energy, valence bond, and fraction packing) and external factors (density) on the microwave properties of ceramics were also studied. The ceramic exhibited excellent microwave dielectric performances, with a relative permittivity (Ɛr) of 21.2, a quality factor (Q × f) of 52 360 GHz, and a temperature coefficient of resonant frequency (τf) of −44.2 ppm/°C, when sintered at 1500 °C for 4 h. The τf value of the La2MgGeO6 ceramic doped with CaTiO3 could be adjusted to zero. Particularly, 0.2La2MgGeO6-0.8CaTiO3 ceramics have good microwave dielectric properties with τf = +2.1 ppm/°C, Q × f = 15 610 GHz, and Ɛr = 40.3.

Novel 0.695CaTiO3-0.305SmAlO3+xwt% CeO2 (x = 0, 0.5, 1.0, 1.5) ceramics were fabricated using a reaction-sintering (RS) approach. The crystal structure, morphology, and microwave dielectric properties of ceramics were systematically studied. The addition of CeO2 could effectively improve the sintering behavior of 0.695CaTiO3-0.305SmAlO3 (CTSA) ceramics. When x = 0.5 wt%, the ceramics exhibited optimal microwave dielectric properties, with er = 43.9, Q×f = 48 779 GHz, and τƒ = −0.24 ppm/°C, thereby indicating that the samples prepared via the RS route possess superior dielectric properties compared to those prepared by the conventional solid phase reaction. The results demonstrate that CaTiO3-SmAlO3 ceramics can be prepared simply and efficiently through a reaction-sintering process.

NaTaO3 ferroelectric ceramics sintered at 1550 °C exhibit high relative permittivity and outstanding microwave dielectric properties of er = 113.76, Q × f = 8824 GHz, and τƒ = +645 ppm/°C in the low-frequency band (3.5195 GHz). The high relative permittivity is advantageous for the miniaturization of modern wireless communication devices. A near zero temperature coefficient of the resonance frequency (τƒ = +1.05 ppm/°C) and good microwave dielectric properties (Q × f = 54,680 GHz, er = 19.42) were obtained for 0.92MgTiO3-0.08NaTaO3 ceramics. Moreover, the sintering temperature of MgTiO3 could be decreased from 1350 °C to 1200 °C. Hence, NaTaO3 is a high-potential microwave dielectric material for adjusting systems with a negative temperature coefficient of resonance frequency.

We propose a plasma-activated direct bonding process at low temperatures (≤200 °C) to form heterostructures between single-crystalline SiC and conventional Si-based substrates (SiO2, Si, and glass) without any interlayers. Surface activation was performed via an inductively coupled O2 plasma for 60 s with a lower bombardment damage position. The SiC surfaces were much more hydrophilic after activation, and the generation of defect states was suppressed. Consequently, void-free and robust bonding interfaces of SiC/SiO2, SiC/Si and SiC/glass were successfully achieved. There were no carbon-enriched layers across the bonding interfaces, which could improve the electrical properties of SiC-based devices. Additionally, the bonding interface of SiC/glass exhibited excellent optical transparency, and interfacial corrosion resistance was confirmed via immersion tests in biological solutions. This bonding method provides a feasible route towards industry-compatible heterogeneous integration of single-crystalline bulk SiC onto Si-based platforms for electronic, optical, mechanical, and biomedical applications.

Using the solid-state reaction method, novel series of 3CaO–RE2O3–2WO3 (RE = La, Nd and Sm) dielectric ceramics materials were fabricated, and the crystal structure and microstructure were studied through X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The Ca3La2W2O12 (CLW) ceramic exhibited a single pure phase with a rhombohedral structure, and Ca3Nd2W2O12 (CNW) and Ca3Sm2W2O12 (CSW) ceramics had similar crystal structures with CLW. 3CaO–RE2O3–2WO3 (RE = La, Nd and Sm) ceramics are packed tightly, and the grains exhibited clear boundaries and uniform size. The CLW, CNW, and CSW ceramics sintered at 1375 °C for 4 h possessed excellent microwave dielectric properties: Ɛr = 19.1, Q × f = 34370 GHz, τf = − 80 ppm/°C; Ɛr = 19.3, Q × f = 36610 GHz, τf = − 74 ppm/°C and Ɛr = 18.8, Q × f = 23240 GHz, and τf = − 68 ppm/°C, respectively. Moreover, the (1 − x)CNW–xTiO2 (0.3 ≤ x ≤ 0.6) and (1 − y)CNW–yCaTiO3 (0.4 ≤ y ≤ 0.7) ceramics were designed and prepared to get a thermally stable material. The addition of TiO2 and CaTiO3 had a significant impact on the performances of ceramics. With increasing the TiO2 and CaTiO3 content, the relative permittivity (Ɛr) and temperature coefficient of resonance frequency (τf) values of ceramics increased, but the quality factor (Q × f) values of ceramics decreased. Especially, 0.55CNW–0.45TiO2 and 0.45CNW–0.55CaTiO3 ceramics sintered at 1375 °C for 4 h had microwave dielectric properties of Ɛr = 22.4, Q × f = 32,490 GHz, and τf = − 0.5 ppm/°C and Ɛr = 23.4, Q × f = 6440 GHz, and τf = − 1.5 ppm/°C, respectively.

Biodegradable biomaterials coated with active factors are effective medical devices to promote wound healing. However, the current strategies of adding active factors generally cause the degradation of biomaterials or damage to the bioactivity of the active factors. In this study, aimed at developing a simple strategy for promoting the surface-active factor functionalization of biomaterials, graphene oxide (GO) was chosen as an adhesive polymeric bridge-layer between the substrate poly(lactide-co-glycolide) (PLGA), ponericin G1, and basic fibroblast growth factor (bFGF). The surface morphology, physical properties, hydrophilicity, cytocompatibility, and antibacterial activity of the resultant composite biofilms were studied. According to the results obtained, the ponericin G1 and bFGF-grafted PLGA/GO composite biofilms (bFGF/ponericin G1@PLGA/GO) showed improved mechanical properties, excellent hydrophilicity, good compatibility, and effective antibacterial activity. Finally, the effect of the bFGF/ponericin G1@PLGA/GO composite biofilms on wound healing was investigated on a rat full-thickness skin wound model. In vivo wound closure and histological and immunofluorescence evaluations revealed that the bFGF/ponericin G1@PLGA/GO composite biofilms could effectively accelerate wound healing and exhibit a lower inflammatory reaction. Hence, the above-mentioned results suggest that the bFGF/ponericin G1@PLGA/GO composite biofilms may have huge potential in biomedical and skin-wound repair applications.

Direct bonding at low temperature is an attractive technology for joining dissimilar materials without large thermal stress. Vacuum ultraviolet (VUV) activation is an effective way for surface cleaning with less damage. Meanwhile, the obtained hydrophilic surfaces are also beneficial for the direct bonding. In this paper, we developed a VUV/O3 activated bonder for the direct bonding of Si-based materials at low temperature. High bonding strength for Si/glass and glass/glass bonded pairs was achieved after annealing at 200 oC. Atomic force microscopy (AFM) and water contact angle tester were conducted to analyze effects of VUV on surface roughness and wettability. Si-Si, Si-glass and glass-glass bonding interfaces were also observed by transmission electron microscopy (TEM). Defect-free and tight interfaces of Si/Si and Si/glass were obtained. However, the glass/glass bonding interface was full of microvoids which can be attributed to the less deformation of subsurfaces during the annealing process. Moreover, based on the surface and interface studies, bonding mechanisms for Si-based materials direct bonding via VUV activation was discussed.

A controllable plasma-activated method to achieve pressureless sintering of Ag nanoparticles is proposed for low-temperature bonding. O2 plasma activation is employed to effectively decompose organics coated on the nanoparticles prior to sintering, avoiding the loose interfacial microstructures. Therefore, robust bonding Cu-Cu joints with high shear strength (>20 MPa) can be formed at a low temperature of 200 °C without requiring additional pressure. This rapid and controllable activation method significantly enhances the sinterability of the Ag particles, leading to a dense microstructure. The improved thermal conductivity is three times higher than the one prepared without plasma activation.