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Three-dimensional (3D) porous boron-doped diamond (BDD) film is an attractive electrode material but tough to synthesize. Herein, the 3D porous BDD films were constructed in a facile and template-free way. The BDD/non-diamond carbon (NDC) composite films were firstly fabricated by hot filament chemical vapor deposition (HFCVD) technique, and then the porous BDD films with 3D interconnected porous microstructure, different pore size and NDC-free diamond were achieved by selective removal of NDC. It is manifested that higher electrochemical response, large double layer capacitance (17.54 mF/cm2) in diamond electrodes, wide electrochemical window of 2.6 V and superior long-term stability were achieved for 3D porous BDD film. This derives from the synergistic effect of microstructure and phase composition of the porous films. 3D interconnected structure possesses prominent improvement of effective surface area and accessible porous channel, significantly enhancing the species adsorption and mass transfer. The 3D porous BDD films, composed of NDC-free diamond, exhibit excellent structural stability and corrosion resistance, which favor the enhancement of long-term stability and water splitting overpotential. The facile fabricating approach and excellent structure/electrochemical character demonstrate the appealing application in many electrochemical fields for 3D porous BDD films, such as energy storage and conversion, wastewater treatment and purification.

To tackle the dissolution problem of boron carbide particles in silicon infiltration process, carbon-coated boron carbide particles were fabricated for the preparation of the reaction-bonded boron carbide composites. The carbon coating can effectively protect the boron carbide from reacting with liquid Si and their dissolution, thus maintaining the irregular shape of boron carbide particles and preventing the growth of boron carbide particles and reaction formed SiC regions. Furthermore, the nano-SiC particles, originated from the reaction of the carbon coating and the infiltrated Si, uniformly coated on the surfaces of boron carbide particles, thus forming a ceramic skeleton of the nano-SiC particles-coated and -bonded boron carbide particles. The Vickers hardness, flexural strength and fracture toughness of the composites can be increased by 26 %, 45 %, and 37 % respectively, by using carbon-coated boron carbide particles as raw materials.

The inclined magnetohydrodynamic (MHD) unsteady flow and heat transfer of Casson hybrid nanofluid (HNF) due to porous stretching sheet is investigated. In the present paper we analyze the Casson fluid unsteady flow over permeable flat plate in the presence of inclined magnetic field and heat transfer of fluid with the effect of thermal radiation. The conservation of mass, conservation of momentum and thermal equations are non-dimensional into the system of nonlinear ODEs by taking the suitable similarity transformation. An exact analytical solution is obtained for velocity. The energy equation in the presence of inclined magnetic field and radiation is a differential equation with variable coefficients, which is transformed to an incomplete gamma function using a new variable and using the Rosseland approximation for the radiation. The governing differential equations are solved analytically and the effects of various parameters on velocity profiles, skin friction coefficient, temperature profile and wall heat transfer are presented graphically. There is an enhancement in heat transfer and pressure drop by usage of HNF. The variations in velocity and temperature profiles with respect to different various pertinent physical parameters. An increase of the mass transpiration (suction) parameter intensity increases the skin friction, which consequently improves the heat transfer enhancement and reduces the HNF temperature. Furthermore, the skin friction coefficient increases due to mass suction and MHD in the stretching sheet, whereas the rate of heat transfer decays. The results have possible technological applications in liquid-based systems involving stretchable materials.

Tremendous demands for highly sensitive and stable seawater salinometers have motivated intensive research on advanced electrode materials. Boron-doped diamond (BDD) is attractive in terms of its high mechanical stability and chemical inertness, but is usually hindered by its low double-layer capacitance (Cdl) for seawater salinity detection. Here, inspired by the principle of oxygen-terminated BDD electrode endowing higher Cdl than hydrogen-terminated surface, we introduce the oxygen terminated surface by oxygen plasma or reactive ion etch (RIE), and the fabricated oxygen terminated BDD electrodes demonstrate high sensitivity and long-term stability in seawater salinity detection comparing with the hydrogen terminated BDD electrodes. Significantly, the as-fabricated O-BDD-RIE electrodes not only show remarkable enhanced response even better than the commercial platinum black electrodes but also display long-time stability which is weekly verified by continuous monitor for 90 days. The outstanding performance of the oxygen terminated BDD electrodes can be ascribed to the enhancement of C-O surface functional group on Cdl. In addition, a comprehensive analysis of effective electroactive surface area (EASA) and Cdl proves that the surface oxygen is the major factor for the improved Cdl. In summary, the excellent oxygen terminated BDD electrodes promise potential application in seawater salinity detection.

The TiO2-Ag hybrid nanofluids were prepared by diluting high-concentration nanofluids and adding Span80 as surfactants. The stability of nanofluids was studied by taking photos of the nanofluids with storage time of 0–30 days. The thermal conductivity and dynamic viscosity were measured at different volume fraction, temperature and ultrasonication time. The results showed that compared with the base fluid, the maximum enhancement of thermal conductivity was 9.98%, and the maximum dynamic viscosity ratio was 2.78. And ultrasonication treatment is recommended to alleviate the sedimentation of nanofluids. Then, two artificial neural networks (ANNs) were established and the size of the networks was optimized according to the relative error to improve the ability to predict the thermal properties of nanofluids. The results show that the maximum relative error of the prediction of thermal conductivity and dynamic viscosity is 1.44% and 3.54%, respectively, which is beneficial to saving experiment time and cost.

Hybrid perovskites are emerging as a promising, high-performance luminescent material; however, the technological challenges associated with generating high-resolution, free-form perovskite structures remain unresolved, limiting innovation in optoelectronic devices. Here, we report nanoscale three-dimensional (3D) printing of colored perovskite pixels with programmed dimensions, placements, and emission characteristics. Notably, a meniscus comprising femtoliters of ink is used to guide a highly confined, out-of-plane crystallization process, which generates 3D red, green, and blue (RGB) perovskite nanopixels with ultrahigh integration density. We show that the 3D form of these nanopixels enhances their emission brightness without sacrificing their lateral resolution, thereby enabling the fabrication of high-resolution displays with improved brightness. Furthermore, 3D pixels can store and encode additional information into their vertical heights, providing multilevel security against counterfeiting. The proof-of-concept experiments demonstrate the potential of 3D printing to become a platform for the manufacture of smart, high-performance photonic devices without design restrictions.

The dependence of interfacial contact resistance (ICR) on contact materials between cathode and interconnect is systematically studied under both isothermal oxidation and thermal cycling conditions. Three kinds of cathode current-collecting layer (CCCL) are used, (La,Sr) (Co,Fe)O3 (LSCF), LSCF+10%Ag, and Ag, and tested in a SUS430/CCCL/SUS430 sandwich structure to simulate the actual operation of the solid oxide fuel cells (SOFCs). Experimental results show that the ICR of LSCF+10%Ag exhibits the smallest value, in comparison with the specimens with LSCF and Ag paste, as well as the sample without a CCCL. For LSCF+10%Ag contact, the ICR increases from 0.0069 mΩ cm2 to 3.74 mΩ cm2 under an isothermal condition for 150 h, then increases from 3.74 mΩ cm2 to 10.79 mΩ cm2 after 15 thermal cycles. This work provides information for the understanding of possible mechanisms of performance degradation of SOFCs.

Hydrogen therapy has recently received increasing attention as an emerging and promising therapeutic technology due to its selective antioxidant property and cell energy regulatory capability in vivo. To solve the low solubility issue of hydrogen, a variety of nanomaterials and devices for hydrogen supply have recently been developed, aiming to increase the concentration of hydrogen in the specific disease site and realize controlled hydrogen release and combined treatment. In this review, we mainly focus on the latest advances in using hydrogen-generating devices and nanomaterials for hydrogen therapy. These developments include sustained release of H2, controlled release of H2, versatile modalities of synergistic therapy, etc. Also, bio-safety issues and challenges are discussed to further promote the clinical applications of hydrogen therapy and the development of hydrogen medicine.

Titanium dioxide (TiO2) has a long history of application in blood contact materials, but it often suffers from insufficient anticoagulant properties. Recently, we have revealed the photocatalytic effect of TiO2 also induces anticoagulant properties. However, for long-term vascular implant devices such as vascular stents, besides anticoagulation, also anti-inflammatory, anti-hyperplastic properties, and the ability to support endothelial repair, are desired. To meet these requirements, here, we immobilized silver nanoparticles (AgNPs) on the surface of TiO2 nanotubes (TiO2-NTs) to obtain a composite material with enhanced photo-induced anticoagulant property and improvement of the other requested properties. The photo-functionalized TiO2-NTs showed protein-fouling resistance, causing the anticoagulant property and the ability to suppress cell adhesion. The immobilized AgNPs increased the photocatalytic activity of TiO2-NTs to enhances its photo-induced anticoagulant property. The AgNP density was optimized to endow the TiO2-NTs with anti-inflammatory property, a strong inhibitory effect on smooth muscle cells (SMCs), and low toxicity to endothelial cells (ECs). The in vivo test indicated that the photofunctionalized composite material achieved outstanding biocompatibility in vasculature via the synergy of photo-functionalized TiO2-NTs and the multifunctional AgNPs, and therefore has enormous potential in the field of cardiovascular implant devices. Our research could be a useful reference for further designing of multifunctional TiO2 materials with high vascular biocompatibility., Graphical abstract Image 1, Highlights • Photo-functionalized TiO2NTs@Ag composites showed excellent vascular compatibility. • UV irradiation greatly improved the anticoagulant properties of the composites. • Moderately loaded AgNPs strongly inhibited SMCs and MAs, but weakly inhibited ECs.

The controllable release is necessary for ideal drug delivery technologies. Because of their high specific surface area and high porosity, titanium dioxide nanotubes (TNTs) have been widely used as drug carriers in medical devices. By loading copper as the catalyst, nitric oxide (NO) generation was facilitated by catalyzing the decomposition of renewable endogenous NO donors

The effect of the surface wettability of plasma-modified vertical Si nanowire array on the bio-fouling performance has been investigated. The Si nanowires prepared by a metal-assisted chemical etching technique exhibit a super-hydrophilic surface. The treatment in CH4/H2 gas plasma environment leads to the decoration of graphite and diamond nanoparticles around Si nanowires. The detailed interface between graphite/diamond and Si nanowire was characterized by HRTEM technique. These surface-modified nanowire samples show an increased water contact angle with ultrananocrystalline diamond decorated ones being superhydrophobic. The immersion test in chlorella solution reveals that the diamond-coated Si nanowires possess the least attachment of chlorella in comparison with other Si nanowires. This result confirms that the coating of Si nanowires with diamond nanoparticles shows the best behavior in anti-biofouling. Importantly, this work provides a method fabricated super-hydrophobic surface for the application of biofouling prevention.

The rapid re-endothelialization of the vascular stent surface is desirable for preventing thrombosis or reducing restenosis. Many biological factors that promote the biological behavior of endothelial cells have been used for the surface modification of stents. Vascular endothelial growth factor (VEGF), which plays an important role in angiogenesis, induces strong vascular growth. In this study, we investigated different VEGF concentrations (50 to 500 ng/ml) to determine the optimum concentration for biocompatibility. First, VEGF-loaded heparin/poly-l-lysine (Hep-PLL) nanoparticles were created by electrostatic interactions. Then, the VEGF-loaded nanoparticles were immobilized on dopamine-coated 316 L stainless steel (SS) surfaces. The physical and chemical properties of the modified surface were characterized and the biocompatibility was evaluated in vitro. The results indicated that the VEGF-loaded nanoparticles were immobilized successfully on the 316LSS surface, as evidenced by the results of Alcian Blue staining and water contact angle (WCA) measurements. The low platelet adhesion and activation indicated that the modified surfaces had good blood compatibility. The modified surfaces showed a good inhibitory effect on smooth muscle cells, indicating that they inhibited tissue hyperplasia. In addition, the modified surfaces significantly promoted endothelial cell adhesion, proliferation, migration, and biological activity, especially VEGF concentration was 350 ng/ml (NPV350). The optical VEGF concentration of the surface modified Hep-PLL nanoparticles was 350 ng/ml. The proposed method shows promise for potential applications for cardiovascular devices.

Integration of two or more biomolecules with synergetic and complementary effects on a material surface can help to obtain multi-functions for various biomedical applications. However, the amounts of biomolecules integrated and their physiological functions are compromised due to the limited surface anchoring sites. Herein, we propose a novel concept of film engineering strategy “from surface to bulk synergetic modification”. This new concept is realized by employing the surface amine groups of plasma polymerized allylamine (PPAm) film for grafting a molecule e.g., thrombin inhibitor, bivalirudin (BVLD), meanwhile its bulk amine groups is used as a universal depot for storing and releasing therapeutic nitric oxide (NO) gas as supplement to the functions of BVLD. It is demonstrated that such a “from surface to bulk synergetic modification” film engineering can impart the modified-substrates with anti-platelet and anti-coagulant dual functions, giving rise to a highly endothelium-mimetic thromboresistant property. We believe that our research provides a very promising strategy to deliver multifunctional surface versatilely that require NO release in combination with other properties, which will find broad biomedical applications in blood-contacting devices, and et al. Moreover, it also provides a brand-new film engineering strategy for tailoring surface multi-functionalities of a wide range of materials., Graphical abstract Image 1, Highlights • A concept of “from surface to bulk synergetic modification” is proposed for tailoring surface multi-functionalities. • The surface amine groups of plasma polymerized allylamine (PPAm) film were used for grafting bivalirudin. • The bulk amine groups of PPAm film is utilized as the universal depots for storing and releasing nitric oxide.

The integration of sp2-/sp3-bonded carbon has aroused increasing attention on attaining a great electron field emission (EFE) performance. Herein, a novel hierarchical diamond@carbon nanowalls/diam...

This paper conducts a new investigation of air purification with total heat recovery based on nanofluids for the first time to realize the synergistic application of nanofluids to the heat and mass transfer as well as the photocatalysis and sterilization fields. To explore the feasibility of the new application, the stable TiO2 nanofluids were obtained by a post-treated optimized preparation method. Then the experimental device is built to investigate the formaldehyde and total volatile organic compounds (TVOC) purification as well as sterilization. At last, the heat recovery characteristics of nanofluids are indirectly investigated by testing the gas-liquid bubbling heat transfer behaviour. The results show the post-treated method can improve the dispersion stability of nanofluids. The nanofluid system has efficient effects on air purification and sterilization for both fungi and bacteria. The nanofluids have higher gas-liquid bubbling heat transfer performance than water which increased as the particle loading.

Silicon vacancy (SiV) centers in CVD-deposited nanodiamond particles or films always exhibit a photoluminescent (PL)-quenching behavior. Herein, in order to overcome this issue, air annealing of nanocrystalline diamond (NCD) films with uniform doping of Si atoms is employed to improve the PL emission efficiency of SiV centers. Without severe mass loss in diamond, SiV centers exhibit an increased PL emission intensity at 738 nm with an increased annealing temperature and time. In comparison to the untreated film, the maximum PL enhancement reaches about 200 and 1473 folds when the NCD films are annealed at 600 °C for 60 min and 700 °C for 20 min, respectively. Such giant increase in SiV PL emission is mainly attributed to the transition of diamond surface from hydrogen to oxygen termination together with the optimized crystalline quality of the annealed films, as confirmed by the HRTEM, Raman and XPS measurements. A schematic model based on the theory of surface band bending is proposed to elucidate the mechanism of the SiV PL enhancement in oxygen-terminated NCD films: a near-surface light trap layer formed in hydrogen-terminated NCD is converted during the oxidation process, leading to the additional collection of SiV PL emission from the inner layer.

Nowadays, the stability and heat transfer properties of nanofluids have been extensively studied. However, for the practical application, the dynamic stability, sedimentation, and fouling characteristics are also important issues. Whether nanofluids can maintain stable heat transfer characteristics during intermittent operation in the system is also a worthwhile issue. In this paper, the dynamic stability, sedimentation, and fouling characteristics as well as the time-dependent heat transfer characteristics of TiO2 and CNT nanofluids are investigated sequentially. The results show that compared with static condition, the dispersion stability of nanofluids is much better, and the sedimentation and fouling on solid surface are much less in dynamic condition. For the nanofluids in this paper, the sedimentation and fouling on solid surface are loose and can easily washed out after slight flushing. Rough surfaces are easier to adsorb the nanoparticles sedimentation and form fouling, but it can be greatly removed using ultrasonication. Long-term shutdown reduces the convective heat transfer enhancement of nanofluids, but it can be well restored after the action of ultrasonication.

This article experimentally investigates the cyclic behavior of ultra high performance concrete–filled steel tube beam-columns. A total of eight specimens were tested. The considered parameters were the axial load ratio and steel ratio. The results showed that all ultra high performance concrete–filled steel tube beam-columns had a very good cyclic behavior without significant pinching. Increasing the axial load ratio results in the decrease of strength and ductility, but it has no obvious influence on the initial flexural stiffness. Reducing the steel ratio results in the decrease of the strength, stiffness and ductility, and energy dissipation capacity.

The present study aims at enhancing the thermal performance of SAE 50 engine oil by adding zinc oxide nanoparticles. The investigations are performed in the thermal range of 25 to 55 °C and at the volume fractions of 0.125 to 1.5%. In this regard, first, the characterization of nanoparticles was performed to examine their surface and atomic structure. Moreover, following the manufacture of the nano-lubricant, its stability was investigated by the DLS test. After ensuring the results of nano-lubricant stability, different samples were prepared according to the variations in volume fraction, followed by the experimental measurement of the thermal conductivity of nano-lubricant. The obtained results revealed an ascending trend in thermal conductivity by increasing temperature and concentration. The maximum thermal conductivity enhancement was 8.74%. Based on the experimental results, a sharply precise relation was proposed to predict the ratio of nano-lubricant thermal conductivity to that of the tested base fluid.

Environmentally responsive polymer films have received much attention, but the stability of such films and the sensitivity of the response still have to be improved. The preparation of responsive films for low pH changes still faces challenges. In this study, catechol groups were used to functionalize chitosan and hyaluronic acid for mussel-inspired, catechol based adhesion. The modified chitosan and the modified hyaluronic acid were deposited in a layer-by-layer manner. The chemical properties of the compounds and surface properties of the coatings were characterized by UV, IR, scanning electron microscopy and water contact angles. The assembly and stability of the film were investigated in situ using quartz crystal microbalance (QCM-D). The film had improved stability compared to the native polymers and it showed reversible pH-dependent swelling and shrinkage. The film was loaded with a drug and placed in PBS solutions of different pH for several days, and the amount of drug released by the drug-loaded film was different under different pH environments. This provides ideas for the intelligent application in materials science and biology, and has broad prospects in drug delivery systems and tissue engineering.

The effects of surface adsorption of bovine serum albumin (BSA) and human gamma-globulin (HGG) on the tribological performance of a DLC film were investigated using a quartz crystal microbalance with dissipation (QCM-D), a ball-on-disk reciprocating tribometer, and a three-electrode electrochemical cell. The results showed that the wear depth in the BSA solution was higher than that in the HGG solution. In the HGG solution, the HGG-adsorbed layer could act as a lubricating layer and protect the DLC film from wear. The wear volume of DLC film in BSA and HGG mixture solution was higher than that in single HGG solution. This may be because the BSA molecules inhibit the formation of HGG adsorbed layer during sliding.

The present article makes on the presence of the magnetohydrodynamic (MHD) flow of an electrically conducting Newtonian fluid over a superlinear stretching/shrinking sheet. A similarity transformation is utilized to interpret the representing construction of nonlinear PDEs by nonlinear ODEs. These equations are solved analytically along with the corresponding boundary conditions. The impact of radiation, mass transpiration, and carbon nanotube (CNT) volume fraction on MHD Newtonian fluid flow and heat transfer is under investigation. Water, ethylene glycol, and engine oil are used as base liquids in the sample along with single and multi-walled carbon nanotubes (MCNTs). Heat transfer in an electrically conducting fluid, including internal heat generation and absorption, is evaluated over a continuously stretching/shrinking sheet with power-law surface temperature or heat flux. Furthermore, the heat equation is solved analytically via the Kummer’s function and WKB method, respectively. The studied results verify that CNTs have significant properties in improving heat transfer processes which have been extensively developed in manufacturing industrial applications, especially in nanomedicine, where the use of carbon nanotubes as drug-carriers is being pursued, particularly in cancer treatment.

We have developed a sensitive cryogenic second-harmonic generation microscopy to study a van der Waals antiferromagnet ${\mathrm{MnPS}}_{3}$. We find that long-range N\'eel antiferromagnetic order develops from the bulk crystal down to the bilayer, while it is absent in the monolayer. Before entering the long-range antiferromagnetic ordered phase in all samples, an upturn of the second harmonic generation below 200 K indicates the formation of the short-range order and magnetoelastic coupling. We also directly image the two antiphase (180\ifmmode^\circ\else\textdegree\fi{}) antiferromagnetic domains and thermally induced domain switching down to bilayer. An anomalous mirror symmetry breaking shows up in samples thinner than ten layers for the temperature both above and below the N\'eel temperature, which indicates a structural change in few-layer samples. Minimal change of the second harmonic generation polar patterns in strain tuning experiments indicate that the symmetry crossover at ten layers is most likely an intrinsic property of ${\mathrm{MnPS}}_{3}$ instead of an extrinsic origin of substrate-induced strain. Our results show that second harmonic generation microscopy is a direct tool for studying antiferromagnetic domains in atomically thin materials, and opens a new way to study two-dimensional antiferromagnets.

Macro photography allows direct visualization of the enlarged whole mouse brain by a combination of lightsheet illumination and expansion microscopy with single-cell resolution. Taking advantage of the long working distance of a camera lens, we imaged a 3.7 cm thick, transparent, fluorescently-labeled expanded brain. In order to improve 3D sectioning capability, we used lightsheet excitation confined as the depth of field of the camera lens. Using 4x sample expansion and 5x optical magnification, macro photography enables imaging of expanded whole mouse brain with an effective resolution of 300 nm, which provides the subcellular structural information at the organ level.

In this work, we demonstrate a simple method to prepare carbon nanofiber (CNF) with multilevel gradient porous structure derived from polyvinylidene fluoride (PVDF)- polyvinyl pyrrolidone (PVP) /PVP core-shell nanofiber. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have confirmed that the as-prepared CNF contains a hollow channel embraced by mesoporous and microporous structures. Its specific surface area reaches to 1084 m2/g with the mesoporous volume contribution of 59%. The as-prepared porous CNF shows a high capacitance of 331 F/g at 1 A/g and 99.6% capacitance retention after 10,000 cycles at 5 A/g, which is better than the corresponding CNF with irregularly arranged hierarchical pores. The all-solid-state symmetric supercapacitor assembled using the as-prepared porous CNF as electrodes exhibits an excellent high specific capacitance of 147.4F/g at 1 A/g with a high energy density of 13.1 W h/kg. The capacitance retention still maintains at 89.2% after 2000 cycles at a current density of 5 A/g. Meanwhile, the as-prepared porous CNF also shows a high CO2 adsorption uptake, 5.08 mmol/g at 0 °C and 1 bar. The possible reason and mechanism have been discussed.

Two simple methods are proposed to respectively impart external force-free reversible shape memory effect to commercial polyolefins: ultrahigh molecular weight polyethylene (UHMWPE) and polypropylene (PP). The key issues lie in the utilization of the partially entangled molecular chains of UHMWPE and the medium crystalline phases of PP as the reversible internal stress providers. The acquired reversible shape memory effect further proves to be applicable for assisting repeatedly self-healing of wider cracks. Compared to the conventional approaches, which used to introduce cross-linkages into the target materials, the present ones only need physical treatment, so that the valuable thermoplasticity of polyolefins is retained. This work can be regarded as an example of the concept "physically converting instead of chemically modifying" for the preparation of functional polymeric materials based on market available plastics.

The present work is focused on developing external stress-free two-way triple shape memory polymers (SMPs). Accordingly, a series of innovative approaches are proposed for the material design and preparation. Polyurethane prepolymers carrying crystalline polytetrahydrofuran (PTMEG) and poly(ε-caprolactone) (PCL) as the switching phases are respectively synthesized in advance and then cross-linked to produce the target material. The stepwise method is believed to be conducive to manipulation of the relative contribution of PCL and PTMEG. Moreover, the chain extender, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-ol (UPy), is incorporated to establish hydrogen bonds among the macromolecules. By straightforward stretching treatment at different temperatures, the hydrogen bond networks are successfully converted into an internal stress provider, which overcomes the challenge of stress relaxation of the melted low melting temperature polymer (i.e., PTMEG) and increases the efficiency of stress transfer. Meanwhile, the contraction force of the switching phases is tuned to match the internal tensile stress. As a result, the internal stress provider can closely collaborate with melting/recrystallization of the crystalline domains, leading to the repeated multiple shape memory effects. The cross-linked polyurethane is thus able to reversibly morph among three shapes and displays its potentials as soft robot and actuator. The strategy reported here has the advantages of easily accessible raw materials, simple reaction, and facile programing/deprograming/reprograming, so that it possesses wide applicability.

Pickering High Internal Phase Emulsions (HIPEs) stabilized by food-grade particles have received considerable attention. In this work, we first demonstrated the use of chitosan-caseinophosphopeptides (CS-CPP) nanocomplexes as particulate emulsifiers to stabilize the interface of natural oils and water. For this purpose, we developed the CS-CPP nanocomplexes through electrostatic interactions and demonstrated their application in the formation of stable Pickering HIPEs. The microstructures, e.g., interfacial frameworks, of the CS-CPP nanocomplexes partition between the continuous phase and interfacial region, and the states of the droplets of Pickering HIPEs were visualized by confocal laser scanning microscopy (CLSM) and an optical microscope. The compressed droplets in Pickering HIPEs formed a percolating 3D-network framework that endowed emulsions with viscoelastic, self-supporting, and ideal thixotropic features. In addition, the gelatinous state of Pickering HIPEs combined with robust and compact CS-CPP nanocomplexes formed an interfacial layer around the droplets, thus depressing the oxidation of linseed oil. The contents of primary and secondary oxidation products in HIPEs were lower than that in bulk oil and emulsions stabilized by surfactants. An in vitro gastrointestinal (GI) model was constructed to characterize the lipid oxidation, lipid digestion and curcumin bioaccessibility of Pickering HIPEs. Interestingly, this route enhanced the bioaccessibility of curcumin from 20.49% (bulk oil) to 49.21% (Pickering HIPEs). This work offers a facile method to develop Pickering HIPEs by food-grade particles, which help to fill the gap between the performance of CS-CPP nanocomplexes-stabilized Pickering HIPEs and potential applications as oral delivery systems of nutraceuticals.

Surface modification with poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) is an effective method for improving hemocompatibility. Peptide GREDVY immobilized on Ti is of great benefit to endothelialization. Micropattern of PMPC and GREDVY can regulate cells distribution, behaviors, and nitric oxide (NO) release. Copper can be used as catalytic to release NO from a donor in vitro, which can inhibit platelets adhesion, activation, and aggregation. The Ti-PDA(Cu)-M/R(P) micropattern was fabricated with PMMPC-HD {PMMPC [monomer contain MPC and methacrylic acid (MA)] was cross-linked with hexamethylene diamine} and peptide Gly-Arg-Glu-Asp-Val-Tyr (GREDVY) using PDMS stamp, and it was characterized by SEM, FTIR, and XPS. The results demonstrated that the PMPC and peptide GREDVY were immobilized onto polydopamine successfully. Simultaneously, the copper existed in polydopamine was confirmed by XPS. The rate of NO release in vitro catalyzed by copper ions was 1.5–5.3 × 10−10 mol/(cm2 min). It will be beneficial to inhibiting platelets adhesion and proliferation of ECs.

Functional microdomains consisting of multiple molecules have widespread applications. However, most of available methods reported so far have a common limitation for widespread practical use. Herein, we reported a facile method based on material-independent polydopamine surface chemistry to realize the area-selective immobilization of dual amine-/thiol-terminal bioactive molecules assisted by photolithography. We transferred the photoresist pattern to the polydopamine coating surface, and specific molecules were respectively covalently immobilized in the microdomain. The results demonstrated that molecular anchoring is area-selective and quantitatively controllable. Thus, this versatile method provides a new insight into the creation of regionally chemical multicomponent surfaces and could build a potential platform for promising application in sensors, molecular biology, and genetic diagnosis.

Diamond-like carbon (DLC) films were deposited by electron cyclotron resonance plasma-chemical vapor deposition (ECR-CVD) at different substrate bias potential (Us = −200 and −800 V). The mechanical properties and microstructure uniformity of the DLC films deposited at different positions (the distance between substrate and ECR plasma source, Decr-s) were studied. The results showed that the ionization of acetylene (C2H2) at different positions decreased with the increase of Decr-s at substrate bias potential Us = −200 V. The plasma distribution was non-uniform, so the mechanical properties and structure of the DLC films varied a lot with the change of deposition position. At substrate bias potential Us = −800 V, an additional self-sustained discharge around the substrate could be generated during ECR plasma discharge, then the ionization of C2H2 and the plasma distribution uniformity at different positions were found to be improved. The uniformity of mechanical properties and structure of DLC films could be improved due to enhanced ionization of C2H2 in front of the substrate at high values of the negative substrate bias (Us = −800 V).

Titanium oxide (Ti-O) films with different thicknesses were deposited on 316 L stainless steel and bare metal stents with the filtered cathodic vacuum arc technique. The adhesion of the Ti-O films with different thicknesses on the 316 L stainless steel sheets was studied by the tension test. The adhesion, corrosion resistance, and fatigue behavior of the Ti-O film-modified stents were then evaluated. The results show that a 25-nm-thick Ti-O film on stainless steel is tightly adhered on the stainless steel after 40% relative elongation of the steel substrate. The 25-nm-thick Ti-O film-modified bare metal stent has sufficient mechanical stability, good corrosion resistance, and can withstand 380 million cycles of pulsatile fatigue testing without film destruction and delamination. A clinical trial of the bilayer drug eluting stent (DES) with a titanium oxide base layer and an anti-proliferative sirolimus top layer shows that our DES tends to reduce the incidence of late thrombosis.

Microstructure engineering has aroused tremendous interest to tailor the electrochemical properties of an sp3/sp2-bonded carbon composite in the chemical sensing field. In this work, the undoped di...

Optimal target-sputtering mode for Aluminum Nitride thin film deposition by high power pulse magnetron sputtering (HPPMS)

Owing to its high ionization degree, high power pulsed magnetron sputtering (HPPMS) has proven advantageous for Cu film growth. In this study, Cu films with different thicknesses deposited by HPPMS at different peak powers were prepared. Moreover, a titanium (Ti) interlayer was used to improve the Cu (111) out-of-plane preferred orientation and adhesion. The films prepared at high peak power exhibited high tensile stress, large grain size, and low electrical resistivity. Thicker Cu films exhibited lower stress and larger grain size, resulting in better electrical conductivity and adhesion. At the same time, a Ti interlayer with (002) preferred orientation could greatly improve the (111) out-of-plane preferred orientation and adhesion of the Cu film.

Surface treatment with phenols can be a new controllable anticorrosion strategy for modulating the degradation rate of magnesium implants. In our previous work, the gallic acid (GA) and the hexamethylenediamine (HD) were used to fabricate the GAHD film on the surface of magnesium and exhibited good corrosion resistance. In this work, the mechanism of anticorrosion and controllability of the GAHD film was deeply investigated. The results of SEM, EDX and XPS show that large number of magnesium was chelated into the GAHD film by GA. And the higher content the GA was, the more magnesium was chelated. Furthermore, the results of electrochemical measures and immersion tests show that the GAHD film with higher GA content possessed stronger corrosion resistance. According to these results above, we found the GAHD film deposited on the magnesium was a kind of chemical conversion coating. In the body fluid environment, massive chelated magnesium would transform into insoluble magnesium hydroxide, which are known as a natural corrosion protection substance of magnesium and perform the effect of corrosion protection. And it could easily control the corrosion resistance of the GAHD conversion coating through regulating the content of GA in the coating.

The tribochemical reaction between metal ions and proteins can result in the formation of a carbonaceous tribo-layer on the surface of metal-on-metal (MOM) artificial joints. This carbonaceous film can lubricate the tribo-pair and reduce the corrosion of the metal. The purpose of this work is to investigate the catalysis efficiency of Cu and Co ions in the formation of carbonaceous films at the contact regions. A ball-on-disc (Al2O3-on-Cu and Al2O3-on-Co alloy) friction mode in bovine serum albumin (BSA) solution was chosen for the wear test experiments. After the wear test, the tribo-layer formed on the wear spot (on Al2O3 ball) and wear track (metal disc) were collected and characterized. The results show that the Cu ions released upon friction promoted the adsorption of BSA on the wear track of Cu to give a protein film which was further transformed into a carbonaceous tribo-layer under the shear force between the Al2O3-Cu tribo-pair. When the Al2O3 ball and Co alloy were chosen as the tribo-pair, however, a carbonaceous tribo-layer was not observed on the Co alloy after the wear testing. This means that the catalysis efficiency of the Cu ion for the formation of a carbonaceous tribo-layer is stronger than that of the Co ion.

Hybrid diamond/sp2-C nanostructures have aroused growing interests in electrochemistry currently owing to the good chemical/physical properties, including high electrical conductivity, mechanical robustness and high specific surface area, as well as the unique electrochemical properties, namely, an enhanced electrochemical activity while retaining a wide potential window and low background currents, when properly engineering the microstructure. This mini-review presents the recent electrochemistry process of diamond/sp2-C nanostructures. In particular, the synthetic methods, microstructures and possible growth mechanism of diamond/sp2-C nanostructures are briefly summarized. Then, the electrochemical property tailoring is addressed in detail and subsequently, their potential applications in electrochemistry including electrochemical sensors, supercapacitors, electrocatalysis, and other applications are discussed. The future perspectives of diamond/sp2-C nanostructures in electrochemistry finally conclude this review.

In this study, diamond films were synthesized on silicon substrates by microwave plasma enhanced chemical vapor deposition (CVD) over a wide range of experimental parameters. The effects of the microwave power, CH4/H2 ratio and gas pressure on the morphology, growth rate, composition, and quality of diamond films were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). A rise of microwave power can lead to an increasing pyrolysis of hydrogen and methane, so that the microcrystalline diamond film could be synthesized at low CH4/H2 levels. Gas pressure has similar effect in changing the morphology of diamond films, and high gas pressure also results in dramatically increased grain size. However, diamond film is deteriorated at high CH4/H2 ratio due to the abundant graphite content including in the films. Under an extreme condition of high microwave power of 10 kW and high CH4 concentration, a hybrid film composed of diamond/graphite was successfully formed in the absence of N2 or Ar, which is different from other reports. This composite structure has an excellent measured sheet resistance of 10–100 Ω/Sqr. which allows it to be utilized as field electron emitter. The diamond/graphite hybrid nanostructure displays excellent electron field emission (EFE) properties with a low turn-on field of 2.17 V/μm and β = 3160, therefore it could be a promising alternative in field emission applications.

The development of a facile and versatile strategy to endow surfaces with synergistically anti-inflammatory, antimicrobial, and anticoagulant functions is of particular significance for blood-contacting biomaterials and medical devices. In this work, we report a simple and environmentally friendly "one-pot" method inspired by byssal cuticle chemistry, namely, [Fe(dopa)3] coordination chemistry for assembly of copper ions (Cu2+) and plant polyphenol (tannic acid)/catecholamine (dopamine or norepinephrine) to form metal-phenolic/catecholamine network-based coatings. This one-pot method enabled us to easily develop a multifunctional surface based on the combination of the characteristic functions of metal ions and plant polyphenol or catecholamine. The residual phenolic hydroxyl groups on the coatings imparted the modified surface with excellent antioxidant and anti-inflammatory functions. The robust chelation of copper ions to the metal-phenolic/catecholamine networks provided not only durable antibacterial property but also glutathione peroxidase like catalytic capability to continuously and controllably produce antithrombotic nitric oxide by catalyzing endogenous S-nitrothiol. The biological functions of such coatings could be well regulated by adjusting the ratios of the feed concentration of Cu2+ ions to plant polyphenol or catecholamine. We envision that our simple, multifunctional, and bioinspired coating strategy can hold great application promise for bioengineering blood-contacting devices.

In this study, a coating of ionic Zr integrated in 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) metalorganic-like complexes was applied on Mg for corrosion control. HEDP was first immobilized on alkaline pretreated Mg followed by an alternating dip-coating process of Zr ions and HEDP to build a complex coating on Mg. This coating was demonstrated to be homogeneous, compact and with a metalorganic-like framework firmly anchored on Mg. This coating led to reduced corrosion current densities and remarkably suppressed long-term in vitro degradation of Mg in phosphate buffer saline (PBS). This complex coating showed promise for surface modification of Mg in biodegradable applications.

A facile approach to fabricate an inorganic coating with favorable blood compatibility and accelerating endothelialization is reported. The inorganic coating with various ratios of Cu and Ti atom are prepared on 316 L stainless steel by physical vapor deposition method. The phase composition and structure as well as the element concentration of the coating are investigated by X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio, clotting time and platelet adhesion are utilized to characterize the materials’ hemocompatibility, the copper ion releasing was also investigated via immersing test. The result indicates that copper-titanium coating show good compatibility; however, as the ratio of Cu to Ti increases, the hemolysis ratio also increases. The endothelialization degree was accelerated owing to maintain less than 7.0 μg/ml of Cu2+ concentrate, and endothelial cells proliferate more readily than smooth muscle cells. The results demonstrate that this degradable copper-containing coating is suitable as a new surface modification for vascular stents.

The tooth enamel of vertebrates comprises a hyper-mineralized bioceramic, but is distinguished by an exceptional durability to resist impact and wear throughout the lifetime of organisms; however, enamels exhibit a low resistance to the initiation of large-scale cracks comparable to that of geological minerals based on fracture mechanics. Here we reveal that the tooth enamel, specifically from the giant panda, is capable of developing durability through counteracting the early stage of damage by partially recovering its innate geometry and structure at nano- to micro- length-scales autonomously. Such an attribute results essentially from the unique architecture of tooth enamel, specifically the vertical alignment of nano-scale mineral fibers and micro-scale prisms within a water-responsive organic-rich matrix, and can lead to a decrease in the dimension of indent damage in enamel introduced by indentation. Hydration plays an effective role in promoting the recovery process and improving the indentation fracture toughness of enamel (by ∼73%), at a minor cost of micro-hardness (by ∼5%), as compared to the dehydrated state. The nano-scale mechanisms that are responsible for the recovery deformation, specifically the reorientation and rearrangement of mineral fragments and the inter- and intra-prismatic sliding between constituents that are closely related to the viscoelasticity of organic matrix, are examined and analyzed with respect to the structure of tooth enamel. Our study sheds new light on the strategies underlying Nature's design of durable ceramics which could be translated into man-made systems in developing high-performance ceramic materials. STATEMENT OF SIGNIFICANCE: Tooth enamel plays a critical role in the function of teeth by providing a hard surface layer to resist wear/impact throughout the lifetime of organisms; however, such enamel exhibits a remarkably low resistance to the initiation of large-scale cracks, of hundreds of micrometers or more, comparable to that of geological minerals. Here we reveal that tooth enamel, specifically that of the giant panda, is capable of partially recovering its geometry and structure to counteract the early stages of damage at nano- to micro-scale dimensions autonomously. Such an attribute results essentially from the architecture of enamel but is markedly enhanced by hydration. Our work discerns a series of mechanisms that lead to the deformation and recovery of enamel and identifies a unique source of durability in the enamel to accomplish this function. The ingenious design of tooth enamel may inspire the development of new durable ceramic materials in man-made systems.

Phenotype switching is a characteristic response of vascular smooth muscle cells (vSMCs) to the dynamic microenvironment and contributes to all stages of atherosclerotic plaque. Here, we immersed pure magnesium and AZ31 alloy in the completed medium under cell culture condition, applied the resultant leaching extracts to the isolated contractile rat aortic vSMCs and investigated how vSMCs phenotypically responded to the degradation of the magnesium-based stent materials. vSMCs became more proliferative and migratory but underwent more apoptosis when exposed to the degradation products of pure magnesium; while the AZ31 extracts caused less cell division but more apoptosis, thus slowing cell moving and growing. Noticeably, both leaching extracts dramatically downregulated the contractile phenotypic genes at mRNA and protein levels while significantly induced the inflammatory adhesive molecules and cytokines. Exogenously added Mg ions excited similar transformations of vSMCs. With the liberation or supplementation of Mg2+ , the expression patterns of the pro-contractile transactivator myocardin and the pro-inflammatory transcriptional factor kruppel-like factor 4 (KLF4) were reversed. Overall, the degradation of the Mg-based materials would evoke a shift of the contractile vSMCs to an inflammatory phenotype via releasing Mg ions to induce a transition from the phenotypic control of vSMCs by the myocardin to that by the KLF4. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 988-1001, 2019.

Over the past few decades, plasma surface modification technique has been widely used to selectively improve surface properties and biocompatibility of materials. In this paper, at first a simple and effective method for the deposition of plasma-polymerized allylamine films onto 316L stainless steel (SS) from an allylamine/nitrogen gas mixture was developed. These amine-rich films were characterized by grazing incidence attenuated total reflection Fourier transform infrared spectroscopy (GATR-FTIR) and X-ray photoelectron spectroscopy (XPS), and the anticorrosion properties were demonstrated by electrochemical analysis. Micro-BCA and quartz crystal microbalance with dissipation (QCM-D) results showed that the higher density of amine groups of the allylamine-nitrogen plasma-polymerized film contributes to more serum protein adsorption which may enhance the adhesion and growth of cells on biomaterials. The in vitro and in vivo anti-inflammatory evaluation was performed and it has been confirmed that these nitrogen-rich surfaces could inhibit the activation of macrophages by down-regulation of the pro-inflammatory cytokines TNF-α and IL-6, and exhibit acceptable tissue-compatibility. It was found that with the help of nitrogen, plasma-polymerized allylamine films presented superior biological properties and provided a high potential application in surface modification of biomedical substrate with desirable clinical performance.

Patients with DLC (diamond like carbon)-coated artificial joints may be exposed to a wide size range of DLC wear debris (DW). In this study, the cytotoxicity of DW of different size ranges (0-0.22, 0.22-0.65, 0.65-1.0, and 1.0-5.0 μm) was evaluated. The microstructure and physical characteristics of DW were investigated by Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscope (SEM), and dynamic light scattering (DLS). Macrophages, osteoblasts, and fibroblasts were incubated with DW of different size ranges respectively followed by cytotoxicity evaluations of inflammatory cytokines, alkaline phosphatase (ALP) assays, and related signal protein expression analysis. The results showed that, except for the size range of 0-0.22 μm, DW cytotoxicity showed a size-dependent (0.22-5.0 μm) decrease with increasing size. Within the range of 0.22-5.0 μm, DW of larger size resulted in lessened inflammatory response and enhanced osteoblastogenesis and fibrogenesis, with increased viability of cells (macrophages, osteoblasts, and fibroblasts), better morphology, less release of pro-inflammatory factors and more release of anti-inflammatory factors. The results demonstrated that DW sizes below 0.22 μm had less negative effects on cell adhesion and growth because of the BSA (bovine serum albumin) encapsulation effect. These findings provide valuable knowledge about the comprehensive mechanism of promotion of inflammatory response and inhibition of osteoblastogenesis and fibrogenesis induced by DW. In conclusion, an effective system of biocompatibility evaluation for different sizes of DW was derived.

Magnesium alloys have potential application in cardiovascular stents and orthopedic implants. However, the rapid corrosion rate of magnesium limits their clinical application. In order to improve the corrosion resistance and biocompatibility of the substrate, a protective coating is constructed by alternate immersing of MgZnMn alloy in epigallocatechin gallate (EGCG) and polyethyleneimine (PEI) solution. The conventional method is immersing magnesium alloy into a conversion solution by simple one-step immersion. In the present work, the EGCG/PEI coating is prepared by a novel alternate immersion method. The number of alternate immersions resulted in a different density of phenolic hydroxyl groups and amino groups on the surface. The corrosion resistance and bonding strength of the coating also varied with alternating immersion times. As the corrosion resistance and density of the functional groups varies, endothelial cells (ECs), smooth muscle cells (SMCs), osteoblasts, and macrophages showed a different growth state on EGCG/PEI coatings. In summary, this EGCG/PEI coating addressed the rapid corrosion rate of the magnesium alloy and can adjust its function by controlling the number of alternate immersions. The EGCG/PEI coating exhibited multifunctions: improved corrosion resistance, good compatibility with ECs and osteoblasts, and inhibition of SMC growth and inflammation, and the effective groups on the coating make it possible for further modification by grafting biomolecules. This is an effective method for preparing a multifunctional platform on biomedical magnesium alloys.

Titanium-copper (Ti–Cu) coatings have attracted extensive attention in the surface modification of industrial and biomedical materials due to their excellent physical and chemical properties and biocompatibility. Here, Ti–Cu coatings are fabricated using a combination of high-power pulsed magnetron sputtering (HPPMS, also known as high power impulse magnetron sputtering (HiPIMS)) and DC magnetron sputtering followed by vacuum annealing at varied temperatures (300, 400, and 500 °C). X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) data showed that Ti, Cu, and CuTi3 are mainly formed in the coatings before annealing, while Ti3O, Cu2O, and CuTi3 are the main compounds present in the annealed coatings. The cross-sectional TEM micrographs and corresponding EDS results provided evidence that Ti is mainly present on the surface and interfaces of the silicon substrate and the Ti–Cu coatings annealed at 500 °C, while the bulk of the coatings is enriched with Cu. The resistivity of the coatings decreased with increasing the annealing temperature from 300 to 500 °C. Based on self-corrosion current density data, the Ti–Cu coating annealed at 300 °C showed similar corrosion performance compared to the as-deposited Ti–Cu coating, while the corrosion rate increased for the Ti–Cu coatings annealed at 400 and 500 °C. Stable release of copper ions in PBS (cumulative released concentration of 0.8–1.0 μM) for up to 30 days was achieved for all the annealed coatings. Altogether, the results demonstrate that vacuum annealing is a simple and viable approach to tune the Cu diffusion and microstructure of the Ti–Cu coatings, thereby modulating their electrical resistivity, corrosion performance, and Cu ion release behavior.

Internal gelation has been an important sol-gel route for the preparation of spherical microgel for drug delivery, cell therapy, or tissue regeneration. Despite high homogeneity and permeability, the internal gelated microgels often result in weak mechanical stability, unregular interface morphology and low cell survival rate. In this work, we have extensively improved the existing internal gelation approach and core–shell hydrogel microcapsules (200–600 μm) with a smooth surface, high mechanical stability and cell survival rate, are successfully prepared by using internal gelation. A coaxial flow-focusing capillary-assembled microfluidic device was developed for the gelation. Rapid gelling behavior of alginate in the internal gelation makes it suitable for producing well-defined and homogenous alginate hydrogel microstructures that serve as the shell of the microcapsules. 2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (HEPES) was used in the shell stream during the internal gelation. Thus, a high concentration of acid in the oil solution can be used for better crosslinking the alginate while maintaining high cell viability. We further demonstrated that the gelation conditions in our approach were mild enough for encapsulating HepG2 cells and 3T3 fibroblasts without losing their viability and functionality in a co-culture environment.