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Biomimetic gradient piezoelectric nanofibrous mats fabricated through an easy-to-use method induce selective osteogenic and chondrogenic differentiation by cell self-stimulation.

Incorporation of inorganic piezoelectric ceramic nanoparticles into a highly elastic polymer matrix is an effective method to develop self-powered sensors and energy harvesters. Herein, a piezoelectrically enhanced nanogenerator (NG) obtained by dispersing lead-free BaTiO

Clean supporting information:Figure S1,PLQY.Figure S2, Emission spectra

The mechanical and electrical properties of biomaterials are essential in cell function regulation during cell-biomaterial interaction. However, previous studies focused on probing cell regulation mechanisms under one type of stimulus, and a platform that enables the study of electromechanical coupling effects of a biomaterial on cells is still lacking. Here, we present an in-situ electromechanical testing and loading system to image live cells when co-cultured with electroactive biomaterials. The system can provide accurate and repeatable stretch on biomaterials and cells to mimic in vivo tension microenvironment. Besides, the integrated displacement transducer, force sensor, and electrical signal detector enable the real time detection of electromechanical signals on electroactive biomaterials under various stretch loading. Combined with a microscope, live cell imaging can be realized to probe cell behavior. The feasibility of the system is validated by culturing mesenchymal stem cells on piezoelectric nanofiber and conductive hydrogel. Experiment results show the device as a reliable and accurate tool to investigate electromechanical properties of biomaterials and probe essential features of live cells. Our system provides a way to correlate cell behavior with electromechanical cues directly and is useful for exploration of cell function during cell-biomaterial interaction.

The electromechanical properties of biomaterial are often essential to cell function during cell-biomaterial interaction. We describe the design and validation of an electromechanical testing and loading system for live cell study while co-cultured with biomaterial. The system is extended based on an uniaxial cell stretching device, and we use it to overcome a significant limitation of existing cell stretching devices, in which only strain are considered for cell stimulation. Combining proper mechanical design with high-precision electrical and force sensing, our system can simultaneously examine the mechanical and electrical stimulation on cell function caused by biomaterial. We validate our system by culturing mesenchymal stem cells on piezoelectric nanofiber membrane. The piezoelectric response of the nanofiber membrane is investigated under simulated in vivo stretch loading. Live cell imaging using an inverted microscope are implemented to clarify the manipulation principle of the device. Experiment results demonstrate that our system provides a useful tool for in vitro studies of electromechanical coupling effects of biomaterial on cell.

With the rapid development of high-speed and heavy-load in modern rail transit, the abrasion and surface defect of wheel tread are getting serious, and the demand of measuring the wheel profile and tread surface defect has been increasing. Phase Measuring Profilometry (PMP), due to its good characters of non-contact, high precision, easy to control automatically etc., is often used for precise 3D shape reconstruction. In this paper, PMP technology and Stoilov phase shift algorithm are adopted, three deformed fringe patterns of wheel are collected with fixed phase shift between them, and branch cut phase unwrapping algorithm is used, based on which the three-dimensional surface shape of the wheel is reconstructed and the artificial surface flaws on the tread are restored and measured. This method provides a good reference for the precise online detection of the wheel abrasion and surface defect.

Titanate nanomaterials (TNs) were synthesized via a simple hydrothermal method using TiO2 (ST-01) and NaOH as the raw materials, and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs, such as morphology, structure, surface area, and chemical composition were characterized by XRD, SEM and BET. The adsorption capability and rules of Pb(II) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243.05 m2 x g(-1) to 286.20 m2 x g(-1). TNs with reaction time between 12-36 h mainly showed sheet structure, and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb(II) by TNs-12, TNs-24, TNs-36, TNs-48, TNs-60 and TNs-72 was 479.40, 504.12, 482.00, 388.10, 364.60 and 399.00 mg x g(-1), respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb(II) by TNs-24 followed the pseudo-second-order model, and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min, and the adsorption was an exothermic process, with a high adsorption capacity at low temperature or room temperature; the optimal adsorption pH was 5.0. When pH was 1.0, the desorption rate of TNs-24 could reach 99.00%, and the removal efficiency of Pb(II) by regenerated TNs was still more than 97% after six times of usage. Therefore, TNs could efficiently remove Pb(II) in aqueous solutions, and the optimal reaction time should be controlled to 12-24 h. When Cd(II) or Ni(II) existed in the solution, the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb(II) and H+/Na+ in TNs.