Phase-Controlled Strategy for High-Quality Single-Source Vapor-Deposited Cs₂AgBiBr₆ Thin Films

Environmentally friendly lead-free Cs2AgBiBr6 double perovskites have emerged as potential materials for photovoltaic applications owing to their nontoxicity and high stability. However, the low solubility of precursors in the solution method and the deviated composition in the reported sequential evaporation process are still the challenges to obtain highly pure Cs2AgBiBr6 phase films. In this work, we proposed a single-source vapor deposition process for high-quality Cs2AgBiBr6 films with an effective thermally induced phase-controlled strategy. The microstructure, composition, and photoelectric properties of Cs2AgBiBr6 films with different heat treatments were investigated, and the phase evolution of Cs2AgBiBr6 film formation was figured out. High-phase purity, uniformity, smoothness of the surface, well-defined grain structure, and desired composition stoichiometry of Cs2AgBiBr6 films led to an optimized power conversion of 1.38% for a planar device structure with excellent stability. Our results demonstrate the feasibility of employing a single-source vapor deposition technique to fabricate high-quality double perovskite thin films, which paves the way for further development of various optoelectronic devices based on these promising lead-free semiconductors

Motility enhancement of trophoblast cells in a small physiological EF.

<p>Trophoblast cells in culture exposed to an EF of 150/mm (over 5 hours) showed enhanced migration rate compared with non-EF stimulated cells (0 mV) at field strengths of 100 mV/mm and 200 mV/mm (**p<0.01, respectively).</p

A Small Physiological Electric Field Mediated Responses of Extravillous Trophoblasts Derived from HTR8/SVneo Cells: Involvement of Activation of Focal Adhesion Kinase Signaling

<div><p>Moderate invasion of trophoblast cells into endometrium is essential for the placental development and normal pregnancy. Electric field (EF)-induced effects on cellular behaviors have been observed in many cell types. This study was to investigate the effect of physiological direct current EF (dc EF) on cellular responses such as elongation, orientation and motility of trophoblast cells. Immortalized first trimester extravillous trophoblast cells (HTR-8/SVneo) were exposed to the dc EF at physiological magnitude. Cell images were recorded and analyzed by image analyzer. Cell lysates were used to detect protein expression by Western blot. Cultured in the dc EFs the cells showed elongation, orientation and enhanced migration rate compared with non-EF stimulated cells at field strengths of 100 mV/mm to 200 mV/mm. EF exposure increased focal adhesion kinase (FAK) phosphorylation in a time-dependent manner and increased expression levels of MMP-2. Pharmacological inhibition of FAK impaired the EF-induced responses including motility and abrogated the elevation of MMP-2 expression. However, the expression levels of integrins like integrin α1, α5, αV and β1 were not affected by EF stimulation. Our results demonstrate the importance of FAK activation in migration/motility of trophobalst cells driven by EFs. In addition, it raises the feasibility of using applied EFs to promote placentation through effects on trophoblast cells.</p></div

Inhibiting of FAK activation abrogates the EFs mediated cellular responses including migration/motility and MMP-2 expression.

<p>A, EF stimulated cells without FAK inhibitor treatment; B and C, EF stimulated cells pretreated with 10 μM FAK inhibitor for 5 h and 10 h,respectively. D, Trophoblast cells were pretreated with FAK inhibitor (10 μM) for 1 hour, and then the cells were stimulated by an EF of 150 mV/mm for 5 h and 10 h, respectively. Cells cultured in EF that had not been subjected to inhibitor treatment was used as the control. Cell lysates were prepared after treatment of the cells with EFs and Western blot was done for the expression of MMP-2. Histogram depicting MMP-2 protein levels normalized to GAPDH. The error bars represent the S.E. (**p<0.01). Bar = 50 μm.</p

Trophoblast cells elongated and orientated perpendicularly in the electric field.

<p>Trophoblast cells exposed to small, applied EF (150 mV/mm) showed elongation and perpendicular orientation (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#pone-0092252-g002" target="_blank">Fig 2B</a>), while control cells that were not subjected to EF showed no such responsiveness (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#pone-0092252-g002" target="_blank">Fig 2A</a>). The morphology of control and EF treated cells stained by fluorescein isothiocyanate labeled Phalloidin (for staining F actin) showed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#pone-0092252-g002" target="_blank">Fig 2C and D</a>, respectively. Enhanced elongation and orientation compared with non-EF stimulated cells (control) at field strength of 150 mV/mm (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#pone-0092252-g002" target="_blank">Fig 2E and F</a>, respectively). The error bars represent the S.E.*p<0.05 and **p<0.0001. Bar = 50 μm</p

Effect of EF on expression of integrins.

<p>EF stimulation did not alter the expression of integrins α1, α5, αV and β1 in trophoblast cells (A, B, C and D, respectively). Cell lysates were prepared after treatment of HTR-8/SVneo cells with EFs (150 mV/mm) for 5 and 10 h, respectively, and Western blot was done for the expression of α1, α5, αV and β1 as mentioned in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#s2" target="_blank">Materials and Methods</a>.</p

Effect of EF on the expression of MMP-2 and TIMP-2.

<p>EF stimulation enhanced the expression of MMP-2 (A), but not its endogenous inhibiting molecule TIMP-2 (B). Cell lysates were prepared after treatment of HTR-8/SVneo cells with EFs (150 mV/mm) for 5 and 10 h, respectively, and Western blot was done for the expression of MMP-2 and TIMP-2 as mentioned in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092252#s2" target="_blank">Materials and Methods</a>. A and B are representative of MMP-2 and TIMP-2 protein signal respectively, and house-keeping gene GAPDH as internal controls. Histograms depicting respective MMP-2 and TIMP-2 protein levels normalized to GAPDH. The error bars represent the S.E. (*p<0.05).</p

Salt-Responsive Zwitterionic Polymer Brushes with Tunable Friction and Antifouling Properties

Development of smart, multifunction materials is challenging but important for many fundamental and industrial applications. Here, we synthesized and characterized zwitterionic poly­(3-(1-(4-vinyl­benzyl)-1<i>H</i>-imidazol-3-ium-3-yl)­propane-1-sulfonate) (polyVBIPS) brushes as ion-responsive smart surfaces via the surface-initiated atom transfer radical polymerization. PolyVBIPS brushes were carefully characterized for their surface morphologies, compositions, wettability, and film thicknesses by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), contact angle, and ellipsometer, respectively. Salt-responsive, switching properties of polyVBIPS brushes on surface hydration, friction, and antifouling properties were further examined and compared both in water and in salt solutions with different salt concentrations and counterion types. Collective data showed that polyVBIPS brushes exhibited reversible surface wettability switching between in water and saturated NaCl solution. PolyVBIPS brushes in water induced the larger protein absorption, higher surface friction, and lower surface hydration than those in salt solutions, exhibiting “anti-polyelectrolyte effect” salt responsive behaviors. At appropriate ionic conditions, polyVBIPs brushes were able to switch to superlow fouling surfaces (<0.3 ng/cm² protein adsorption) and superlow friction surfaces (<i>u</i> ∼ 10^–3). The relationship between brush structure and its salt-responsive performance was also discussed. This work provides new zwitterionic surface-responsive materials with controllable antifouling and friction capabilities for multifunctional applications

Supplemental Material, Revised_Supplementary_Information_20180210 - Enhanced sound insulation and mechanical properties based on inorganic fillers/thermoplastic elastomer composites

<p>Supplemental Material, Revised_Supplementary_Information_20180210 for Enhanced sound insulation and mechanical properties based on inorganic fillers/thermoplastic elastomer composites by Wei Fang, Yanpei Fei, Huanqin Lu, Jiangming Jin, Mingqiang Zhong, Ping Fan, Jintao Yang, Zhengdong Fei, Feng Chen and Tairong Kuang in Journal of Thermoplastic Composite Materials</p

Structural Dependence of Salt-Responsive Polyzwitterionic Brushes with an Anti-Polyelectrolyte Effect

Some polyzwitterionic brushes exhibit a strong “anti-polyelectrolyte effect” and ionic specificity that make them versatile platforms to build smart surfaces for many applications. However, the structure–property relationship of zwitterionic polymer brushes still remains to be elucidated. Herein, we aim to study the structure-dependent relationship between different zwitterionic polymers and the anti-polyelectrolyte effect. To this end, a series of polyzwitterionic brushes with different cationic moieties (e.g., imidazolium, ammonium, and pyridinium) in their monomeric units and with different carbon spacer lengths (e.g., CSL = 1, 3, and 4) between the cation and anion were designed and synthesized to form polymer brushes via the surface-initiated atom transfer radical polymerization. All zwitterionic brushes were carefully characterized for their surface morphologies, compositions, wettability, and film thicknesses by atomic force microscopy, contact angle measurement, and ellipsometry, respectively. The salt-responsiveness of all zwitterionic brushes to surface hydration and friction was further examined and compared both in water and in salt solutions with different salt concentrations and counterion types. The collective data showed that zwitterionic brushes with different cationic moieties and shorter CSLs in salt solution induced higher surface friction and lower surface hydration than those in water, exhibiting strong anti-polyelectrolyte effect salt-responsive behaviors. By tuning the CSLs, cationic moieties, and salt concentrations and types, the surface wettability can be changed from a highly hydrophobic surface (∼60°) to a highly hydrophilic surface (∼9°), while interfacial friction can be changed from ultrahigh friction (μ ≈ 4.5) to superior lubrication (μ ≈ 10^–3). This work provides important structural insights into how subtle structural changes in zwitterionic polymers can yield great changes in the salt-responsive properties at the interface, which could be used for the development of smart surfaces for different applications