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Currently, biomineralization is widely used as a surface modification approach to obtain ideal material surfaces with complex hierarchical nanostructures, morphologies, unique biological functions, and categorized organizations. The fabrication of biomineralized coating for the surfaces of scaffolds, especially synthetic polymer scaffolds, can alter surface characteristics, provide a favorable microenvironment, release various bioactive substances, regulate the cellular behaviors of osteoblasts, and promote bone regeneration after implantation. However, the biomineralized coating fabricated by immersion in a simulated body fluid has the disadvantages of non-uniformity, instability, and limited capacity to act as an effective reservoir of bioactive ions for bone regeneration. In this study, in order to promote the osteoinductivity of 3D-printed PCL scaffolds, we optimized the surface biomineralization procedure by nano-topographical guidance. Compared with biomineralized coating constructed by the conventional method, the nano-topographically guided biomineralized coating possessed more mineral substances and firmly existed on the surface of scaffolds. Additionally, nano-topographically guided biomineralized coating possessed better protein adsorption and ion release capacities. To this end, the present work also demonstrated that nano-topographically guided biomineralized coating on the surface of 3D-printed PCL scaffolds can regulate the cellular behaviors of USCs, guide the osteogenic differentiation of USCs, and provide a biomimetic microenvironment for bone regeneration.

Highlights A multi-scale conductive network was constructed in flexible PDMS/Ag@PLASF/CNT composite with micro-size Ag@PLASF and nano-size CNT. The PDMS/Ag@PLASF/CNT composite showed outstanding electrical conductivity of 440 S m-1 and superior electromagnetic interference shielding effectiveness of up to 113 dB. The PDMS/Ag@PLASF/CNT composites owned good retention (> 90%) of electromagnetic interference shielding performance even after subjected to a simulated aging strategy or 10,000 bending-releasing cycles. Abstract Highly conductive polymer composites (CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference (EMI) shielding materials, which can be used for the electromagnetic interference protection of flexible electronic devices. It is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive networks. In this paper, a novel silver-plated polylactide short fiber (Ag@PLASF, AAF) was fabricated and was integrated with carbon nanotubes (CNT) to construct a multi-scale conductive network in polydimethylsiloxane (PDMS) matrix. The multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m−1 and ultra-strong EMI shielding effectiveness (EMI SE) of up to 113 dB, containing only 5.0 vol% of AAF and 3.0 vol% of CNT (11.1wt% conductive filler content). Due to its excellent flexibility, the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy (60 °C for 7 days) and 10,000 bending-releasing cycles. This strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace, environment and sensitive circuits against radiation for flexible electronic devices.

Polymer matrices have limited abilities to dissociate lithium salts and transport ions, thus making most solid-state polymer electrolytes (SPEs) have extremely low ionic conductivities (10−7–10−5 S/cm) at 25 ℃. In this work, a high-energy electron-beam (e-beam) irradiation is applied to a poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] SPE to improve the ionic conductivity. P(VDF-TrFE) easily shows pure all-trans (TTTT) conformation with all fluorine atoms located on one side of the carbon chain to provide an ion transport highway. E-beam irradiation keeps large amounts of TTTT conformation of P(VDF-TrFE) and produces –CF3 side groups, where the latter expands the interchain distance to split the large ferroelectric domains into nanosize to induce a unique relaxor ferroelectric behavior. This enhances the dielectric constant of the irradiated P(VDF-TrFE) from 15 to 20 and thus facilitates lithium salt dissociation. As a consequence, the ionic conductivity of the irradiated P(VDF-TrFE) SPE is increased from 5.8 × 10−5 to 1.6 × 10−4 S cm−1 at 25 ℃. The solid-state Li//Li symmetrical cell cycles for more than 3000 h at 25 ℃ without a short circuit. Furthermore, the solid-state LFP//Li cell cycles stably for more than 350 cycles with a capacity retention of around 91.3% at 1 C and 25 ℃. This study paves a new way to prepare high-performance SPEs by inducing high dielectric constants and abundant TTTT conformations through e-beam irradiation.

Predicting stress–strain curves is key to facilitate the design of polymer materials and their products with tailored mechanical response. However, due to their structural complexity, polymeric solids generally feature complex stress–strain curves, which renders it challenging to model their stress–strain behaviors. Here, using the categorized knowledge of stress–strain curves, a “Classification-Embedded Dual Neural Network (CDNN)” framework is introduced to accurately predict the mechanical evolution of polymeric solids, by taking the example of injection-molded isotactic polypropylene. Upon built, the dual model is a parallel coupling of a “curve type classifier” and a “curve feature predictor” that predict, respectively, the stress–strain curve categories and their feature points that dictate the extent of similarity between two arbitrary curves in the same category, regardless of the curve complexity. Importantly, with the aid of curve-categorized knowledge, the CDNN strategy offers an update-to-date best balance in model accuracy (20% curve error in maximum) and simplicity (300 neurons in total), which greatly enhances the model’s extrapolability and interpretability and, in turn, mitigates the demanding data requirement (27 samplings from a 4D space, that is, a material design space consisting of 4 design dimensions to tune the structure). Overall, this work establishes a simple, robust methodology in predicting polymeric solids’ stress–strain curves and is potentially generic to a variety of materials.

Highlights The cationic waterborne polyurethanes microspheres with Diels-Alder bonds were synthesized for the first time. The electrostatic attraction not only endows the composite with segregated structure to gain high electromagnetic-interference shielding effectiveness, but also greatly enhances mechanical properties. Efficient healing property was realized under heating environment. Abstract It is still challenging for conductive polymer composite-based electromagnetic interference (EMI) shielding materials to achieve long-term stability while maintaining high EMI shielding effectiveness (EMI SE), especially undergoing external mechanical stimuli, such as scratches or large deformations. Herein, an electrostatic assembly strategy is adopted to design a healable and segregated carbon nanotube (CNT)/graphene oxide (GO)/polyurethane (PU) composite with excellent and reliable EMI SE, even bearing complex mechanical condition. The negatively charged CNT/GO hybrid is facilely adsorbed on the surface of positively charged PU microsphere to motivate formation of segregated conductive networks in CNT/GO/PU composite, establishing a high EMI SE of 52.7 dB at only 10 wt% CNT/GO loading. The Diels–Alder bonds in PU microsphere endow the CNT/GO/PU composite suffering three cutting/healing cycles with EMI SE retention up to 90%. Additionally, the electrostatic attraction between CNT/GO hybrid and PU microsphere helps to strong interfacial bonding in the composite, resulting in high tensile strength of 43.1 MPa and elongation at break of 626%. The healing efficiency of elongation at break achieves 95% when the composite endured three cutting/healing cycles. This work demonstrates a novel strategy for developing segregated EMI shielding composite with healable features and excellent mechanical performance and shows great potential in the durable and high precision electrical instruments.

Piezoelectric polymers usually have rather low piezoelectric coefficients less than 30 pC/N. Here, the authors achieve a highly piezoelectric polymer (d 33 = −62 pC/N) based on a poled biaxially oriented poly(vinylidene fluoride) with a pure β phase due to the mobile oriented amorphous fraction.

Astrocyte activation is an important cause of neuropathic pain. Inhibiting the hyperactivation of astrocytes is beneficial to control over neuropathic pain. However, there is a lack of non-pharmaceutical ways to inhibit the hyperactivation of astrocytes. This study aimed at regulating the activity of glial cells via the architecture of 3D porous scaffolds. Herein, the 3D porous scaffolds with co-continuous and oriented pores were prepared via solid-phase stretching of co-continuous polymer blends followed by selective phase extraction. Compared to the isotropic scaffold, the proliferation of astrocytes slowed down on the oriented scaffolds. Meanwhile, the expression of growth factors and inflammatory factors secreted by astrocyte activation was inhibited by the oriented pores. It led to the suppression of the Wnt/β-catenin signaling pathway that is crucial to determine chronic neuropathic pain. Immunofluorescence staining displayed that the hyperactivation of astrocytes was inhibited, and the expression of kindlin-1, a key protein that activates astrocytes, was downregulated. The proposed strategy offers a probable physical means to relieve neuropathic pain.

3D-printing technology can be used to construct personalized bone substitutes with customized shapes, but it cannot regulate the topological morphology of the scaffold surface, which plays a vital role in regulating the biological behaviors of stem cells. In addition, stem cells are able to sense the topographical and mechanical cues of surface of scaffolds by mechanosensing and mechanotransduction. In our study, we fabricated a 3D-printed poly(ε-caprolactone) (PCL) scaffold with a nanotopographical surface and loaded it with urine-derived stem cells (USCs) for application of bone regeneration. The topological 3D-printed PCL scaffolds (TPS) fabricated by surface epiphytic crystallization, possessed uniformly patterned nanoridges, of which the element composition and functional groups of nanoridges were the same as PCL. Compared with bare 3D-printed PCL scaffolds (BPS), TPS have a higher ability for protein adsorption and mineralization in vitro. The proliferation, cell length, and osteogenic gene expression of USCs on the surface of TPS were significantly higher than that of BPS. In addition, the TPS loaded with USCs exhibited a good ability for bone regeneration in cranial bone defects. Our study demonstrated that nanotopographical 3D-printed scaffolds loaded with USCs are a safe and effective therapeutic strategy for bone regeneration.

Construction of segregated structures within conductive polymer composites (CPCs) is a prospective strategy to enhance electromagnetic interference (EMI) shielding effectiveness (SE). However, the CPCs of segregated structures frequently experience worsened mechanical performances due to weak interface reactions between adjacent polymer domains, which are hindered by conductive fillers. Herein, 3D-printed segregated carbon nanotube (CNT)/polylactic acid (PLA) composite was firstly exploited to develop high mechanical properties while achieving good performance for electromagnetic interference shielding. Within the final 3D-printed CNT/PLA composite, CNTs coated on 3D-printed PLA scaffold were translated to interconnected conductive network after compression. Thus, EMI SE of composite was as high as 67.0 dB when 5.0 wt% CNTs were loaded. Furthermore, 3D-printed PLA scaffold with a highly continuous structure also benefited the mechanical robustness of the segregated composite, revealing the bending strength (87.8 MPa) and Young's modulus (4.43 GPa), which were 101% and 43% higher than 43.7 MPa and 3.08 GPa for the conventional CNT/PLA composite. Moreover, the regulation of 3D-printed PLA scaffolds results in promising CNT/PLA composites with tunable EMI SE. This work suggests that 3D printing technology is an effective and easy approach to develop the outperformance of CPCs for different radiation source fields and electronic devices.

Human serum albumin (HSA) is an important component of plasma, which has the functions of maintaining colloid osmotic pressure and capillary membrane stability, promoting blood circulation, and anti-oxidation. Three-dimensional structure of HSA determines its ability to bind and transport hormones and other substances. In this study we examined the interactions between HSA and ginsenoside Rg3, Rg5, Rk1, Rh2, and Rh4, which are the main cytotoxic ginsenosides extracted from red ginseng. Heat transfer generated by the specific interaction between HSA and each ginsenoside was measured using isothermal titration calorimetry (ITC) assay, which demonstrated that all these 5 ginsenosides bound to HSA with binding constants of 3.25, 1.89, 6.04, 2.07, and 5.17 × 105 M−1, respectively. Molecular docking also displayed that these ginsenosides interact with HSA at different sites of the HSA surface. Importantly, cell viability assay showed that the cytotoxicity of these ginsenosides reduced significantly at the presence of HSA in human vascular endothelial cells (HUVEC). Taken together, this study reveals the mechanism by which these ginsenosides are transported in vivo by not causing damage in vascular endothelium, and also suggests HSA might be an ideal carrier help to transport and execute these ginsenoside functions in human body.

Measuring gas content is an essential step in estimating the commerciality of gas reserves. In this study, eight shale core samples from the Mouye-1 well were measured using a homemade patented gas desorption apparatus to determine their gas contents. Due to the air contamination that is introduced into the desorption canister, a mathematical method was devised to correct the gas quantity and quality. Compared to the chemical compositions of desorbed gas, the chemical compositions of residual gas are somewhat different. In residual gas, carbon dioxide and nitrogen record a slight increase, and propane is first observed. This phenomenon may be related to the exposure time during the transportation of shale samples from the drilling site to the laboratory, as well as the differences in the mass, size and adsorptivity of different gas molecules. In addition to a series of conventional methods, including the USBM direct method and the Amoco Curve Fit (ACF) method, which were used here for lost gas content estimation, a Modified Curve Fit (MCF) method, based on the ‘bidisperse’ diffusion model, was established to estimate lost gas content. By fitting the ACF and MCF models to gas desorption data, we determined that the MCF method could reasonably describe the gas desorption data over the entire time period, whereas the ACF method failed. The failure of the ACF method to describe the gas desorption process may be related to its restrictive assumption of a single pore size within shale samples. In comparison to the indirect method, this study demonstrates that none of the three methods studied in this investigation (USBM, ACF and MCF) could individually estimate the lost gas contents of all shale samples and that the proportion of free gas relative to total gas has a significant effect on the estimation accuracy of the selected method. When the ratio of free gas to total gas is lower than 45%, the USBM method is the best for estimating the lost gas content, whereas when the ratio ranges from 45% to 75% or is more than 75%, the ACF and MCF methods, are the best options respectively.

AIM: To conduct a comparative study of effectiveness of silicone hydrogel contact lens and hydrogel contact lens, which are used in patients after laser-assisted subepithelial keratomileusis (LASEK). METHODS: Sixty-three patients (121 eyes) with a spherical equivalent ≤-5.0 D were chosen after undergoing LASEK in 2012 at Guangdong General Hospital. They were randomly divided into 2 groups. The silicone hydrogel group included 32 cases (61 eyes) that wore silicone hydrogel contact lenses for 4-6d after the operation, while the hydrogel group included 31 cases (60 eyes) who wore hydrogel contact lenses for 4-6d after the operation. Patients’ self-reported postoperative symptoms (including pain, photophobia, tears, and foreign body sensation) were evaluated. The healing time of the corneal epithelium, the visual acuity of patients without contact lens after epithelial healing, and the incidence of delayed corneal epithelial shedding were also assessed. The follow-up time was 1mo. RESULTS: Postoperative symptoms were milder in the silicone hydrogel group than in the hydrogel group. There were significant differences in pain, foreign body sensation, and photophobia between the 2 groups (P0.05). The healing time of the corneal epithelium in the silicone hydrogel lens group was markedly shorter than that in the hydrogel group (4.07±0.25 vs 4.33±0.82d, t=2.43, P=0.02). Visual acuity without contact lenses after healing of the corneal epithelium was better in the silicone hydrogel group compared with the hydrogel group (χ2=7.76, P=0.02). There was no significant difference in the occurrence of delayed corneal epithelial shedding between the 2 groups (P>0.05). CONCLUSION: Patients with LASEK using silicon hydrogel contact lenses had less discomfort and shorter corneal epithelial healing time compared with those using hydrogel contact lenses, suggesting that silicon hydrogel contact lenses may be considered to be a better choice of bandage contact lens after LASEK.

In this paper, the dispersion of carbon nanotube (CNT) in ethylene vinyl acetate (EVA) is demonstrated to be significantly improved by the addition of octadecylamine (ODA)-grafted graphene oxide (GO) (GO–ODA). Compared to the CNT/EVA composite, the resultant GO–ODA/CNT/EVA (G–CNT/EVA) composite shows simultaneous increases in tensile strength, Young’s modulus and elongation at break. Notably, the elongation at break of the G–CNT/EVA composite still maintains a relatively high value of 1268% at 2.0 wt % CNT content, which is more than 1.6 times higher than that of CNT/EVA composite (783%). This should be attributed to the homogeneous dispersion of CNT as well as the strong interfacial interaction between CNT and EVA originating from the solubilization effect of GO–ODA. Additionally, the G–CNT/EVA composites exhibit superior electrical conductivity at low CNT contents but inferior value at high CNT contents, compared to that for the CNT/EVA composite, which depends on the balance of CNT dispersion and the preservation of insulating GO–ODA. Our strategy provides a new pathway to prepare high performance polymer composites with well-dispersed CNT.

Biodegradable poly (lactic acid) (PLA) usually has a crystallinity less than 10% due to its poor crystallization ability. In this work, we found high pressure could significantly facilitate formation of crystallites of PLA, resulting in a crystallinity high up to 66.3% at pressure and temperature of 300 MPa and 185 ºC. High-pressure induced crystalline reorganization and lamellar thickening led to two melting temperatures in the highly crystallized PLA but without cold crystallization compared to the normal-pressure crystallized PLA. Temperature dependence of high-pressure crystallization of PLA suggested desirable crystallization temperatures for highly crystallized PLA products.

A knotty issue concerning the poor mechanical properties exists in the porogen leaching approach to porous scaffolds, despite its advantage in tuning pore structure. To address this hurdle, solid state extrusion (SSE) combined with porogen leaching was utilized to engineer porous scaffolds of poly(lactic acid) (PLA). Advances introduced by poly(ethylene glycol) (PEG) caused the PLA ductile to be processed and, on the other hand, enabled the formation of interconnected pores. Thus, a well-interconnected porous architecture with high connectivity exceeding 97% and elevated porosity over 60% was obtained in the as-prepared PLA scaffolds with the composition of NaCl higher than 75.00 wt % and PEG beyond 1.25 wt %. More strikingly, the pore walls of macropores encompassed countless micropores and rough surface topography, in favor of transporting nutrients and metabolites as well as cell attachment. The prominent compressive modulus of the PLA scaffolds was in the range of 85.7–207.4 MPa, matching the normal modulus of human trabecular bone (50–250 MPa). By means of alkaline modification to improve hydrophilicity, biocompatible porous PLA scaffolds exhibited good cell attachment. These results suggest that the SSE/porogen leaching approach provides an eligible clue for fabricating porous scaffolds with high mechanical performance for use as artificial extracellular matrices.

Radiative cooling glass with spectral selectivity is an effective energy-saving strategy for buildings and vehicles. Nevertheless, the current research still has limitations; for example, the absorption of ultraviolet light by the glass results in a large amount of heat generated inside the space, which affects the radiative cooling performance. Herein, distinct spectral bands of solar radiation are precisely controlled through independently designing epsilon-near-zero (ENZ) regions within the hyperbolic metamaterials (HMMs) composed of Ag/SiO2 and Ag/TiO2 nanoscale-thick layers, which exhibit outstanding spectral regulation capability. The HMM glass features a high visible light transmittance (0.654), superior near-infrared reflectance (0.858), and good ultraviolet reflectance (0.576), while also possessing a high infrared emissivity of 95.6% in the atmospheric window. Outdoor simulation results suggest that with a convective heat transfer coefficient of 6 W/(m² K), the internal equilibrium temperature of the HMM glass can be reduced by 32.8°C compared to that of normal glass. Furthermore, the HMM glass can save up to 91.8-216.4 MJ/m² of cooling energy annually in China in comparison to normal glass. The radiative cooling glass showcased in this work, with its superior spectral regulation capabilities, plays a crucial role in energy conservation and fostering sustainable progress and thus makes it suitable for use in building glass curtain walls or roofs, vehicles windows, and so on. [ABSTRACT FROM AUTHOR]