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Abstract The current primary treatment approach for malignant pelvic tumors involves hemipelvic prosthesis reconstruction following tumor resection. In cases of Enneking type II + III pelvic tumors, the prosthesis necessitates fixation to the remaining iliac bone. Prevailing methods for prosthesis fixation include the saddle prosthesis, ice cream prosthesis, modular hemipelvic prosthesis, and personalized prosthetics using three-dimensional printing. To prevent failure of hemipelvic arthroplasty protheses, a novel fixation method was designed and finite element analysis was conducted. In clinical cases, the third and fourth sacral screws broke, a phenomenon also observed in the results of finite element analysis. Based on the original surgical model, designs were created for auxiliary dorsal iliac, auxiliary iliac bottom, auxiliary sacral screw, and auxiliary pubic ramus fixation. A nonlinear quasi-static finite element analysis was then performed under the maximum load of the gait cycle, and the results indicated that assisted sacral dorsal fixation significantly reduces stress on the sacral screws and relative micromotion exceeding 28 μm. The fixation of the pubic ramus further increased the initial stability of the prosthesis and its interface osseointegration ability. Therefore, for hemipelvic prostheses, incorporating pubic ramus support and iliac back fixation is advisable, as it provides new options for the application of hemipelvic tumor prostheses.

The 7075 Al alloy fabricated using laser powder bed fusion (L-PBF) technology exhibits coarse columnar grains and significant thermal cracking, which hinders it from meeting mechanical and corrosion resistance standards. In this study, 2 wt% micron-sized the Ti6Al4V (TC4) powder was mechanically mixed into 7075 Al alloy powder, resulting in the fabrication of an Al alloy characterized by fine equiaxed grains through the L-PBF process. The resulting alloy sample exhibited no cracks, with an average grain size of 2.016 nm. During solidification, Al3Ti cubic particles formed in situ, serving as heterogeneous nucleation sites, while the Ti element, which possesses a high growth limiting factor (Q value), further facilitates the heterogeneous nucleation of grains. The mechanical properties of the alloy were significantly improved, achieving an ultimate tensile strength of 369.204 MPa and an elongation at break of 9.371%, which is more than nine times greater than that of the L-PBF 7075 Al alloy. Furthermore, the corrosion current density decreased from 9.096E-06 to 2.089E-06, indicating a marked enhancement in the alloy's corrosion resistance. This method has the potential to be applied to the L-PBF of other low-weldability, high-strength Al alloys, thereby laying the groundwork for expanding the industrial applications of L-PBF.

Abstract Liquid-solid contact electrification (CE) is essential to diverse applications. Exploiting its full implementation requires an in-depth understanding and fine-grained control of charge carriers (electrons and/or ions) during CE. Here, we decouple the electrons and ions during liquid-solid CE by designing binary superhydrophobic surfaces that eliminate liquid and ion residues on the surfaces and simultaneously enable us to regulate surface properties, namely work function, to control electron transfers. We find the existence of a linear relationship between the work function of superhydrophobic surfaces and the as-generated charges in liquids, implying that liquid-solid CE arises from electron transfer due to the work function difference between two contacting surfaces. We also rule out the possibility of ion transfer during CE occurring on superhydrophobic surfaces by proving the absence of ions on superhydrophobic surfaces after contact with ion-enriched acidic, alkaline, and salt liquids. Our findings stand in contrast to existing liquid-solid CE studies, and the new insights learned offer the potential to explore more applications.

Abstract The ultrahigh flexibility and elasticity achieved in freestanding single-crystalline ferroelectric oxide membranes have attracted much attention recently. However, for antiferroelectric oxides, the flexibility limit and fundamental mechanism in their freestanding membranes are still not explored clearly. Here, we successfully fabricate freestanding single-crystalline PbZrO3 membranes by a water-soluble sacrificial layer technique. They exhibit good antiferroelectricity and have a commensurate/incommensurate modulated microstructure. Moreover, they also have good shape recoverability when bending with a small radius of curvature (about 2.4 μm for the thickness of 120 nm), corresponding to a bending strain of 2.5%. They could tolerate a maximum bending strain as large as 3.5%, far beyond their bulk counterpart. Our atomistic simulations reveal that this remarkable flexibility originates from the antiferroelectric-ferroelectric phase transition with the aid of polarization rotation. This study not only suggests the mechanism of antiferroelectric oxides to achieve high flexibility but also paves the way for potential applications in flexible electronics.

NiTi alloys exhibit significant potential for biological applications, and the fabrication of customized NiTi geometries is greatly facilitated by the use of laser powder bed fusion (LPBF) processing. However, there are several challenges with post-processing NiTi specimens processed via LPBF, such as uneven, loosely packed, weakly corrosive surfaces, and low dimensional precision. Therefore, solving the surface problem of metals prepared by LPBF has become the key to the application. In this paper, the influence of the solution and parameters on surface roughness, surface shape and size, composition, and corrosion resistance was studied by adjusting the composition of the polishing solution and polishing parameters. The results show that polishing for 2 h in S2 solution (HNO3: HF: H2O = 40:10:50) produces the smoothest surface with the roughness characteristics Sa is 10.41 ± 0.63 μm and Ra is 0.39 ± 0.30 μm. At the same time, the corrosion resistance of polished samples has been significantly improved in simulated body fluids (SBF), and the corrosion current density (Icorr) reduced by up to one order of magnitude, reaching 5.38 ± 0.24 × 10−8. By altering the polishing process duration, it is possible to achieve a micron-level roughness surface while maintaining dimensional accuracy, making LPBF-NiTi more suitable for implant applications. Ultimately, we conclude with a brief discussion of how chemical polishing affects the handling of materials with complex structures. Between 30 and 1 h, LPBF-NiTi scaffolds were polished in S2 solution to provide porosities and dimensional accuracy that best matched the design parameters.

Abstract Flexible electronics strongly demand the integration of flexible and large‐scale multifunctional oxides. BiFeO3 is one of the most essential multifunctional oxides that could be used in memories, logics, sensors, and actuators. Recently, freestanding single‐crystalline BiFeO3 membranes exhibited superior elasticity and flexibility. However, fabrication and integration of large‐scale freestanding BiFeO3 membranes into flexible electronics remain elusive. In this study, inch‐scale freestanding single‐crystalline BiFeO3 membranes are fabricated with assistance from a water‐soluble sacrificial layer. To transfer flat and crack‐free membranes, all the existing methods are first followed but fail. Then the study introduces a temporary supporting Cu layer on the surface of the as‐grown SiTiO3/Sr3Al2O6/(SrRuO3/)BiFeO3 heterostructure and successfully obtains full and crack‐free 5 mm × 5 mm freestanding membranes on various substrates. The residual strain within the heterostructure releases gradually under the protection of the Cu layer. The freestanding BiFeO3 membranes are relatively uniform among different regions and exhibit good dielectric, ferroelectric, and ferromagnetic properties. Finally, flexible ferroelectric photovoltaic devices are patterned based on those BiFeO3 membranes, and they have open circuit voltage and short circuit current density up to −0.25 ± 0.03 V and 0.82 ± 0.09 µA cm−2, respectively.

Nickel-titanium (NiTi) is the most ordinarily used shape memory alloy (SMAs), which has important implications in aerospace, medical devices and so on. However, NiTi parts were limited in their application scope and ability due to the difficulty of processing. Until the appearance of laser powder bed fusion (LPBF) technology, it overcame NiTi alloy preparation's multiple challenges and became the preferred method to fabricate NiTi alloy. Nevertheless, the NiTi parts fabricated by LPBF that have a great shortage still exist in corrosion resistance. Therefore, in this paper, a series of micro-nano structures with different characteristics were constructed in LPBF-NiTi by orthogonal experiment for the first time, which wants to explore the degree of influence of various parameters on the wettability of samples. After variance analysis, the nanolaser processing parameters which are most suitable for constructing lotus leaf structures on NiTi alloy surfaces are obtained. The surface morphology and composition were studied by SEM, XRD, EDS, and XPS, respectively. Finally, the corrosion resistance of samples was tested by electrochemical analysis. The results show that the laser power during processing has the greatest influence on the surface morphology of LPBF-NiTi alloy. And the wettability is affected by surface morphology and –CF/-CF2 adsorption. Furthermore, we compared the corrosion resistance of the superhydrophobic samples which was obtained based on the variance analysis with that of the substrate in 3.5 wt% NaCl solution. The result shows that the corrosion resistance and corrosion stability of superhydrophobic samples are brilliantly increased compared with the substrate.

Abstract Friction is a fundamental force that impacts almost all interface-related applications. Over the past decade, there is a revival in our basic understanding and practical applications of the friction. In this review, we discuss the recent progress on solid-liquid interfacial friction from the perspective of interfaces. We first discuss the fundamentals and theoretical evolution of solid-liquid interfacial friction based on both bulk interactions and molecular interactions. Then, we summarize the interfacial friction regulation strategies manifested in both natural surfaces and artificial systems, focusing on how liquid, solid, gas, and hydrodynamic coupling actions mediate interfacial friction. Next, we discuss some practical applications that are inhibited or reinforced by interfacial friction. At last, we present the challenges to further understand and regulate interfacial friction.

Abstract Selective laser melting of nickel‐titanium alloy (SLM‐NiTi) can precisely control the size of the sample molding structure and has attracted extensive attention due to its special superelasticity and shape memory effect. However, the biological inertness and poor corrosion resistance of SLM‐NiTi alloy limit their wide application as biomedical implant materials. In this study, polycaprolactone (PCL) coating was prepared on SLM‐NiTi alloy by dipping and pulling method, and the effects of alkali heat pretreatment on the morphology, adhesion, corrosion resistance, long‐term stability and biomineralisation of the PCL coatings were investigated. The results showed that PCL coating can substantially improve the performance of SLM‐NiTi alloy, and the PCL coating after alkali heat pretreatment has higher adhesion (increased from 1,747 to 2,498 mN) and lower corrosion current density (reduced by about an order of magnitude compared to PCL coating alone). In addition, the necessary stability, biomineralisation and biocompatibility ability of coatings were also further improved. Therefore, the alkali heat pretreated PCL‐coated SLM‐NiTi alloy has good application prospects in implants due to its superior properties.

In this work, we show that selective laser surface remelting, apart from modifying the microstructure, can also act as a design method to treat the surface of AZ91D magnesium alloy with varying treatment patterns, thus providing a feasible approach to tailor the electrochemical behaviour and to improve its corrosion resistance. Two treatment patterns, spots and stripes, are designed, in which cases, the boundary ratio and geometrical complexity are analyzed and compared. Besides microstructure, Hydrogen evolution, and potentiodynamic polarization curves are studied. It is found that in the central treated area, corrosion is hindered by formation of the greatly refined β-Mg17Al12 continuous network, together with the uniform distribution of surface potential. As a comparison, in the boundary region, extensive micro/galvanic couples are detrimental to the corrosion resistance, due to the oriented dendritic microstructure. As a result, good corrosion resistance, 3–5 times higher than the as-received material, is obtained despite of the variation of treatment patterns and presence of extensive micro/galvanic couples in the boundary region, indicating that selective laser surface remelting could act as a feasible way to tailor the corrosion behaviour of AZ91D. It is suggested that this technique provides not only a metallurgical approach, and also a design one to improve the corrosion resistance of AZ91D, which may lead to numerous applications of both AZ91D and laser surface treatment.

Based on the microstructure of biological femur, the femur-like multimodal surface structures are designed. But they exhibit fracture behavior when the porosity changes, resulting in structural failure. The high curvature surface factor is introduced to improve the fracture behavior of the biomimetic surface structure. Combine the high curvature surface factor to construct novel biomimetic homogenized surface structures. Novel radial gradient surface structures and axial gradient surface structures are designed based on the construction concept of cone functions and linear functions gradients. Theoretical, experimental and numerical methods are used to investigate the mechanical properties of novel biomimetic multimodal surface structures. Euler theory states that the properties of lattice structures are determined by the relative density of structures. The load distribution in the radially gradient structure is uniform, and the deformation mode presents overall failure, which can achieve better resistance and dissipation of the load. The deformation modes of axial gradient structures present layered failure. The underlying mechanism of the difference in mechanical properties of biomimetic multimodal structures is explained in detail. It’s very important significance for targeted application in protective engineering.

Recently, laser powder bed fusion of nitinol alloys (LPBF-NiTi) has attracted much attention due to its ability to precisely form complex parts. However, the wear and corrosion resistance is crucial for practical applications of LPBF-NiTi alloys. Rare earth oxides are common additives used to improve the surface properties of alloys. In this work, nano-sized cerium oxide (CeO2) is selected as the additive, and the influence rule and mechanism of different addition amounts of CeO2 on the surface properties of LPBF-NiTi alloy are deeply studied. The results showed that the addition of an appropriate amount of CeO2 (0.03 wt% CeO2 addition) could effectively refine the grains and improve the grain order, which achieved the improvement of the mechanical properties (tensile strength and toughness) of the LPBF-NiTi alloy. Furthermore, the reduction in friction coefficient and wear scar depth/width proved that the addition of CeO2 effectively improves the wear resistance of LPBF-NiTi alloys, which were mainly attributed to the synergistic action of the precipitation of the secondary hard phase (NiCe), the grain refinement strengthening, and stable phase transformation brought about by high latent heat of transformation. In addition, the improvement of anti-corrosion was reflected in the reduction of corrosion current density Icorr and pitting pits, mainly due to the formation of NiCe precipitates and grain refinement, which effectively hindered the propagation and extension of pitting corrosion. Most significantly, the 0.03% CeO2 sample achieved the simultaneous improvement of mechanical properties and surfaced functional properties, which greatly expanded the application prospects of NiTi–CeO2 alloys.

Selective laser melting (SLM)-fabricated NiTi alloys have attracted widespread interest because they can achieve high-precision preparation of implant materials with complex structures. However, as an implant material, SLM-NiTi alloy exhibits poor osteogenic and excessive release of Ni ions. In this investigation, a bioactive dicalcium phosphate dihydrate (DCPD) coating was prepared on the surface of SLM-NiTi alloy by electrodeposition for the first time to improve the biocompatibility and corrosion resistance of the SLM-NiTi alloys. The influence of coating preparation parameters (deposition current and deposition time) on morphology and corrosion resistance had been studied by SEM, electrochemical and immersion tests. The DCPD coating obtained when the deposition current was 3 mA and the deposition time was 30 min showed a uniform and dense morphology and had the best corrosion resistance, which the corrosion current density Icorr was three orders of magnitude lower than that of SLM-NiTi alloy. Moreover, as the precursor of hydroxyapatite (HA), DCPD effectively promoted the deposition of HA, thus improving the biomineralization property of the SLM-NiTi alloy. The in vitro cell experiments showed that the DCPD coating provided a good interface and microenvironment for the growth and adhesion of osteoblasts. Good corrosion resistance, biocompatibility and biomineralization properties render the DCPD coated SLM-NiTi alloys have great clinical application prospects as biomedical implants.

In this study, we have obtained the corresponding relationship between SLM-NiTi alloy transition temperatures and energy density, and realized the accurate prediction and inverse prediction of SLM process parameters and NiTi alloy transition temperatures. And we verify the accuracy of the prediction model through DSC, XRD and SEM. Secondly, B19′NiTi and B2NiTi are successfully obtained through the prediction model. Finally, a composite gradient NiTi is established based on the idea of rigid-flexible coupling, which successfully achieved the simultaneous improvement of the strength and toughness of the SLM-NiTi alloy. The compressive fracture strength reached 2668 MPa, and the fracture strain reached 55.51%.

In recent years, selective laser melting (SLM)-NiTi had developed rapidly due to the ability to achieve the complex shape and internal features, as well as high dimensional accuracy. The choice of parameters was particularly critical to the forming and performance of SLM-NiTi. In this work, we had designed and prepared five sets of SLM-NiTi shape memory alloys with the same energy density (range of 40–90 J/mm3). The microstructure, phase transition characteristic, mechanical properties and shape memory effect of SLM-NiTi shape memory alloys were investigated through various characterization methods of X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and stress-controlled cyclic tensile tests, etc. The results showed that the surface forming quality of SLM-NiTi was not only related to the energy density, but also related to the value of P/V, which higher than 0.3 or lower than 0.1 would lead to the formation of surface pores. Interestingly, the SLM-NiTi showed ultrahigh failure strength of 735 MPa and elongation of 10.88% under room temperature tensile conditions. In addition, stress-controlled cyclic tensile tests under 400 MPa indicated that the SLM-NiTi had excellent shape memory effect of 76.1% recovery ratio and 3.95% recoverable strain after ten times loading–unloading cycles. The design of multi-parameter variables can not only optimize the surface quality, but also provide a basis for the prediction of SLM-NiTi phase transition temperature.

Surface bacterial fouling has become an urgent global challenge that calls for resilient solutions. Despite the effectiveness in combating bacterial invasion, antibiotics are susceptible to causing microbial antibiotic resistance that threatens human health and compromises the medication efficacy. In nature, many organisms have evolved a myriad of surfaces with specific physicochemical properties to combat bacteria in diverse environments, providing important inspirations for implementing bioinspired approaches. This review highlights representative natural antibacterial surfaces and discusses their corresponding mechanisms, including repelling adherent bacteria through tailoring surface wettability and mechanically killing bacteria via engineering surface textures. Following this, we present the recent progress in bioinspired active and passive antibacterial strategies. Finally, the biomedical applications and the prospects of these antibacterial surfaces are discussed.

The ultrahigh flexibility and elasticity achieved in freestanding single-crystalline ferroelectric oxide membranes have attracted much attention recently. However, for antiferroelectric oxides, the flexibility limit and fundamental mechanism in their freestanding membranes are still not explored clearly. Here, we successfully fabricate freestanding single-crystalline PbZrO3 membranes by a water-soluble sacrificial layer technique. They exhibit good antiferroelectricity and have a commensurate/incommensurate modulated microstructure. Moreover, they also have good shape recoverability when bending with a small radius of curvature (about 2.4 μm for the thickness of 120 nm), corresponding to a bending strain of 2.5%. They could tolerate a maximum bending strain as large as 3.5%, far beyond their bulk counterpart. Our atomistic simulations reveal that this remarkable flexibility originates from the antiferroelectric-ferroelectric phase transition with the aid of polarization rotation. This study not only suggests the mechanism of antiferroelectric oxides to achieve high flexibility but also paves the way for potential applications in flexible electronics. [ABSTRACT FROM AUTHOR]