A simple and facile stereolithography 3D printing technique was utilized to fabricate piezoelectric photopolymer-based polyvinylidene fluoride (PVDF) blends. Different process variables, such as solvent (N,N-dimethylformamide, DMF) to PVDF ratio and PVDF solution to photopolymer resin (PR) ratio, were engineered to enhance the dispersion of the PVDF into the PR so as to achieve the maximum piezoelectric coupling coefficient. Our results demonstrate that a ratio of 1:10 (PVDF:DMF) and 2 wt%-PVDF/PR was optimal for the best dissolution of the PVDF, 3D printability, and piezoelectric properties. Under these conditions, the blend generated ±0.121 nA under 80 N dynamic loading excitation. We believe that the findings of this work would promote many further studies on the mass production of flexible piezoelectric polymer blends with higher quality finished surface and design flexibility.

Enthalpy increments, $\Delta _{298}^T{H^0}$, for highly nonstoichiometric SrFeO3−δ (δ = 0.18–0.41) were obtained between 373 and 1273 K in air using drop calorimetry. The analysis of the $\Delta _{298}^T{H^0}\left( T \right)$ dependence at lower temperatures allowed evaluating the enthalpy of tetragonal to cubic ${{I4} / {mmm}} \,{\tf="TeX CM Bold Maths Symbols"\char33}\, Pm\bar{3}m$ phase transition at 560 K, 1.57 kJ/mol, and the Maier–Kelley function for $\Delta _{298}^T{H^0}\left( T \right)$ of tetragonal SrFeO3−δ (space group ${{I4} / {mmm}}$). Combined investigation of oxygen nonstoichiometry $\bolddelta \left( T \right)$ dependence, measured by thermogravimetry, and higher-temperature $\Delta _{298}^T{H^0}\left( T \right)$ of cubic SrFeO3−δ (space group $Pm\bar{3}m$) yielded the temperature-dependent reduction (oxygen release) enthalpy, $\Delta H_{{\rm{red}}}^{\rm{0}}$. Calorimetrically-determined $\Delta H_{{\rm{red}}}^{\rm{0}}$ of SrFeO3−δ increases from 65 ± 7 kJ/mol O at 873–973 K to 84 ± 7 kJ/mol O at 1073–1273 K, which may indicate that the short-range vacancy ordering in SrFeO3−δ is hampered at higher temperatures.

Electric cell–substrate impedance sensing is widely used to study cell behavior such as adhesion, migration, and cell toxicity. However, a simultaneous optical imaging of cells is limited by inefficient transmission of visible light through the gold electrodes. To overcome this limitation, we fabricated carbon nanotube (CNT) electrodes with high electrical conductivity as well as optical transmittance. The impedimetric monitoring of cell proliferation and migration by gold and CNT electrodes were compared and analyzed. Taking advantage of the optical transparency of CNTs, we demonstrated a simultaneous electronic and optical monitoring of MCF7 cells, with acquisition of high-resolution images.

Wire-shaped supercapacitors (WSSCs) hold great promise in portable and wearable electronics. Herein, a novel kind of high-performance coaxial WSSCs has been demonstrated and realized by scrolling porous carbon dodecahedrons/Al foil film electrode on vertical FeOOH nanosheets wrapping carbon fiber tows (FeOOH NSs/CFTs) yarn electrode. Remarkably, ionogel is utilized as solid-state electrolyte and exhibits a high thermal/electrochemical stability, which effectively ensures the great reliability and high operating voltage of coaxial WSSCs. Benefiting from the intriguing configuration, the coaxial WSSCs with superior flexibility act as efficient energy storage devices and exhibit low resistance, high volumetric energy density (3.2 mW h/cm3), and strong durability (82% after 10,000 cycles). Importantly, the coaxial WSSCs can be effectively recharged by harvesting sustainable wind source and repeatedly supply power to the lamp without a decline of electrochemical performance. Considering the facile fabrication technology with an outstanding performance, this work has paved the way for the integration of sustainable energy harvesting and wearable energy storage units.

Bamboo is a natural composite and one of the most efficient structures in nature because of the relationship of mechanical properties with its microstructural features. This research presents the 3D characterization of the reinforcement bundles of a branching nodal region of bamboo, through high-resolution X-ray microtomography (µCT). µCT was used to characterize a sample regarding the volume, relative density, and porosity of parenchyma and sclerenchyma tissues, and the resulting data were used to estimate their constitutive properties. A nonlinear finite element analysis (FEA) was performed based on a discretized model of the µCT to the limiting compressive load. Secondary bundles presented an interweaved arrangement into the primary vascular elements that distribute axial compressive stresses into new branches. Our findings suggest that the foam-like behavior of the parenchyma, the sclerenchyma thickening above the nodal zone, and the nodal vascular branching are ways for bamboo to protect important tissues from mechanical stress by allocating axial loads. In addition, such mechanism could be applied in the design of biomimetic structures with selective load-bearing capabilities.

A major limitation in nanoindentation analysis techniques is the inability to accurately quantify pile-up/sink-in around indentations. In this work, the contact area during indentation is determined simultaneously using both contact mechanical models and direct in situ observation in the scanning electron microscope. The pile-up around indentations in materials with low H/E ratios (nanocrystalline nickel and ultrafine-grained aluminum) and the sink-in around a material with a high H/E ratio (fused silica) were quantified and compared to existing indentation analyses. The in situ projected contact area measured by Scanning Electron Microscopy using a cube-corner tip differs significantly from the classical models for materials with low H/E modulus ratio. Using a Berkovich tip, the in situ contact area is in good agreement with the contact model suggested by Loubet et al. for materials with low H/E ratio and in good agreement with the Oliver and Pharr model for materials with high H/E ratio.

In this study, Mg-substituted tricalcium phosphate (Mg-TCP) nanoparticles were synthesized by hydrothermal reactions of Mg-calcite mesocrystals from echinoderm skeletons. Following the biomineralization of echinoderms, Mg-calcite powder was synthesized via the solid-state transition of Mg-amorphous calcium carbonate prepared by a wet-chemical precipitation method, which can also be used to fabricate Mg-TCP. We illustrated that Mg-calcite with a certain level of Mg substitution led to the formation of Mg-TCP through the ion-exchange reactions in the hydrothermal system. Therefore, this study provides a new pathway for the synthesis of Mg-TCP nanoparticles.

Chemically modified polymer coatings have been synthesized using a blend of soft polymeric material polydimethylsiloxane (h-PDMS) incorporated with stiff polymer epoxy resin (EP) and was cross-linked using silane compatibilizer 3-aminopropyltriethoxysilane (APTES). A comparative analysis has been carried out between neat epoxy coating (N-EP) and epoxy–hydroxy-terminated polydimethylsiloxane (EP-hPD) blends to study the influence of blending ratio on various properties to cater marine applications. An increase of 144.4% in the Young’s modulus (E) and 37.5% increment in adhesion strength at 30 wt% h-PDMS content was observed as compared with N-EP. The water contact angle results demonstrated a substantial increase in contact angle from 52.3° to 90.1° at 30 wt% h-PDMS content as compared to N-EP. Taber abrasion results revealed a decrease in weight loss (mg/1000 cycles) by 24.1 and 17.7% at 10 and 30 wt% loading of h-PDMS in comparison to N-EP. The surface roughness of N-EP and 30 wt% EP-hPD blend were found to be 33.4 nm and 41.4 nm, respectively. To determine the applicability of the developed blend coatings obligatory tests such as field immersion study and chemical resistance evaluation were conducted, and optimum performance was manifested by EP-hPD blend at an EP:h-PDMS ratio of 70:30.

In the present study, TiO2NT coatings grown on simulated body fluid-based electrolyte were investigated as drug delivery devices. Nanotubes (NTs) were grown over commercially pure Ti and Ti6Al4V alloy. Morphology analysis showed that NTs in alloy samples present an inner diameter of 10 nm smaller in average than NTs grown over pure Ti. The surface wettability in water decreased with the anodizing time for both substrates. The application of coatings as drug delivery devices has been studied through the incorporation of ciprofloxacin. To control the drug release, collagen was used as the diffusional barrier. It was observed the drug release follows a Fick’s kinetics. Bioactivity assays showed the absence of hemolytic activity. The concentration of the drug during the release interval remained below the toxic concentration limit, presenting a bacteriostatic activity. All coatings prepared presented a high antibacterial activity, being the area of inhibition of bacterial growth above 13 times the area of the implant.

A method for rapid quantitative imaging of dopant distribution using secondary ion mass spectrometry (SIMS) is described. The method is based on SIMS imaging of the cross-section of a reference sample with a known concentration profile. It is demonstrated for the case of boron quantification in silicon in a SIMS imaging mode. A nonlinear relationship between the secondary ion intensity and the concentration is observed. A detection limit of 3 (±2) × 1017 at./cm3 (~6 ppm) is determined with 39 nm pixel-size for the used experimental conditions. As an application example, a boron concentration profile in a passivating contact deposited on a textured Si surface is analyzed.

Soiling can lead to severe performance losses of photovoltaic (PV) plants. Within this study, three different anti-soiling coatings (ASC) were applied to three different commercial, solar-grade rolled glasses with different surface structures. Laboratory soiling experiments were performed including wind simulation and a novel rotational force test to assess the influence of different surface structures of the glass substrate on the anti-soiling performance of the coatings. A detailed microscopic evaluation indicates a consistent ranking of the ASC with regard to particle resuspension behavior for both test methods and all substrates. Furthermore, the rotational force test yields a quantitative measure of the median force needed for particle removal from the respective coating, which is independent of the glass substrate surface morphology.