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Development of photoliquefiable solid-state biomaterials at room temperature would address scientific challenges in life science. However, external stimuli-induced phase transitions are difficult for some biomacromolecules based materials, due to the high rigidity of these biomolecules. In this present work, by delicate molecule design on azobenzene-type ammonium surfactants, two new types of DNA-surfactant materials are fabricated. At room temperature, these DNA materials show photoliquefaction of ionic crystals to isotropic liquids under UV light, and fast self-assembly from isotropic liquids back to crystals after ceasing UV light, under the assistance of azobenzene isomerization. To achieve this objective, the designed solid-state DNA materials should have melting points near room temperature and an immediate liquid crystal to isotropic liquid transition process just above the melting points, which highly depends on the stoichiometric charge ratio between DNA and surfactants. As proved by the successful self-healing tests, these DNA ionic crystals are good biomaterials with potential applications in biomedicine and life science. This work would provide a new strategy for designing anhydrous functional biomaterials at room temperature by using rigid biomacromolecules. Statement of Significance At room temperature, solid-state biomaterials with photoregulated crystal⇄isotropic liquid phase transition property are attractive functional materials in life science, considering the body temperature and living environment temperature of human beings. Although several kinds of anhydrous materials achieved isothermal photoresponsive phase transitions, the photoregulated phase transition of anhydrous biomacromolecules based materials has not been achieved at room temperature, due to the high rigidity of these biomolecules. In this work, by delicate molecule design on ammonium surfactants, we synthesized two kinds of anhydrous DNA-surfactants ionic crystals. These DNA materials show fast photoliquefaction under UV light and self-assembly after ceasing light, which affords excellent self-healing biomaterials. This work would provide a new strategy for designing anhydrous photoresponsive biomaterials by using rigid biomacromolecules.

Purpose To use the 4H-SiC material in integrated circuits for high temperature application, an accurate and simple circuit model of n-channel planar 4H-SiC MOSFET is required. Design/methodology/approach In this paper, a SPICE model of n-channel planar 4H-SiC MOSFET was built based on the device simulation results and measurement results. Firstly, a device model was simulated with Sentaurus TCAD, with measured parameters from fabricated planar 4H-SiC MOSFET previously. Then the device simulation results were analyzed and parameters for SPICE models were extracted. With these parameters, an accurate SPICE model was built and simulated. Findings The SPICE model exhibits the same performance as the measured results with different environment temperatures. The simulation results indicate that the maximum fitting error is 0.22 mA (7.33% approximately) at 200 °C. A common-source amplifier with this model is also simulated and the simulated gain is stable at different environment temperatures. Originality/value This paper provides a reliable modeling method for n-Channel Planar 4H-SiC MOSFET and reference value for the design of 4H-SiC high temperature integrated circuit.

A completely water soluble azobenzene chemosensor 1 for selective detection of Hg2+ was synthesized. Taking advantage of the absorption changes corresponding to the transition moments polarized along the short axis of an azobenzene, 1 showed characteristic UV-Vis signal changes in the band around 240 nm for Hg2+ in wide pH ranges, which also showed good tolerance to various metal ions and photoirradiation. Upon addition of Hg2+ into the solution of 1, a favored formation of trans-1 was observed, which is attributed to an intramolecular coordination of the PEG chain and Nβ to Hg2+ confirmed by a control experiment test.

The convective heat transfer of the plume of a 120-N thruster is investigated experimentally and numerically. Numerical results agree well with experimental results in that there is a nonlinear decrease in convective heat transfer with an increasing cone angle. It is also found that convective heat transfer decreases with increasing distance from the thruster outlet. Furthermore, the convective heat transfer of the plume mainly concentrates within a 35° cone angle and the heat flux decreases to the same order as solar radiation at the Earth’s surface when the cone angle exceeds 60°. The results of the study will help improve spacecraft design.

The development of white organic light-emitting diodes (WOLEDs) holds great promise for the production of high-color-quality lighting sources. High quantum efficiencies for the conversion of electrical energy to light have been realized. The color stability and color-rendering index (CRI) become bottleneck for the commercial application of WOLEDs. Here, we employed a metal-free dimerization of 1‑phenyl‑3,5‑diamine‑triazine (DPDT) as a single non-doped emitter in WOLEDs, that exhibits mild efficiency roll-off while maintaining CRI of 92. This high CRI is attributable to the DPDT with efficient monomer and excimer emission, which together emit a relatively wide spectrum that nearly covers the entire range of visible light. The formation of the excimer can make the emission color of single-emitter based WOLEDs tunable with the applied bias over a wide range from blue to pure white.

We have designed and synthesized two α-carboline-based host materials, 1,3-bis(9H-pyrido[2,3-b]indol-9-yl) benzene (mCaP), 2.6-bis(9H-pyrido[2,3-b]indol-9-yl) pyridine (26mCaPy) and two δ-carboline-based host materials, 1,3-bis(5H-pyrido[3,2-b]-indol-5-yl) benzene (mCdP), 2,6-bis(5H-pyrido[3,2-b]indol-5-yl)pyridine (26mCdPy). Their photophysical and electrochemical properties have been fully investigated. It has demonstrated that the photoluminescent quantum yields of δ-carboline-based materials are significanly superior to those of α-carboline-based materials. Carboline unit could coordinate with copper iodide (CuI) to form copper(I) (Cu(I)) complex by co-depositing. Co-deposited films of these carboline derivatives and CuI were fabricated as an emissive layer of the organic light-emitting diodes. Consequently, the device with co-depositing mCdP and CuI as an emitter gave a maximum current efficiency of 37.3 cd A−1, a maximum power efficiency of 26.3 lm W−1.

Three novel host materials, IpCm-PhBzAc (1,3-(4-(12,12-dimethylbenzofuro[3,2-b]acridin-7(12H)-yl)phenyl)-6-isopropyl-4H-chromen-4-one), DpAn-BzAc (2,10-(4-(12,12-dimethylbenzofuro[3,2-b]acridin-7(12H)-yl)phenyl)-10-phenylanthracen-9(10H)-one) and DpTrz-BphBzAc (3,7-(4′-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1′-biphenyl]-4-yl)-12,12-dimethyl-7,12-dihydrobenzofuro[3,2-b]acridine) have been designed and synthesized, and their utilization as host materials for phosphorescent organic light-emitting diodes (PhOLEDs) has been investigated. We have fabricated PhOLEDs using green bis(2-phenylpyridine)iridium(III) acetylacetonate as doped emitters and two hosting schemes, which are the single host system consisting of BzAc derivatives and the co-host system with 1,3-bis(carbazolyl)benzene. We found that the PhOLEDs with the co-host system of DpAn-BzAc and DpTrz-BphBzAc achieved CEs of 57.1 cd A−1 and 53.0 cd A−1, with corresponding efficiency roll-off of only 7.6% and 0.9%, respectively, from the maximum to the practical brightness of 5000 cd m−2. Extremely reduced efficiency roll-off values for BzAc-based PhOLEDs were attributed to their superior thermal stability and excellent bipolar transport properties, and a small singlet–triplet energy gap also afforded efficient reverse intersystem crossing, thus reducing the triplet density of the host for PhOLEDs.

A multifunctional solution-processed composite hole-injection layer (HIL), based on the blends of magnetic nanoparticles (NPs) Fe3O4@G–poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), Fe3O4@SiO2–PEDOT:PSS and Fe3O4@Au–PEDOT:PSS, was used for application in high performance tris-(8-hydroxyquinoline) aluminum-based organic light emitting diodes (OLEDs). Compared to the control devices, a significant increase in the current efficiency of OLEDs with a composite HIL was realized, achieving maximum luminous efficiencies of 5.13 cd A−1 (Fe3O4@G–PEDOT:PSS and Fe3O4@Au–PEDOT:PSS HIL), and of 4.83 cd A−1 (Fe3O4@SiO2–PEDOT:PSS HIL), corresponding to a 35% and 38.2% increase in current efficiency, respectively. The increase in the performance of the OLEDs is attributed to the collective effects of light-scattering, localized surface plasmon resonance (LSPR) and the magnetic effect induced by the magnetic NPs in the HIL.

For perovskite solar cells with carbon electrodes (CPSCs) prepared using undoped hole transport materials and commercial carbon pastes, the poor interfacial carrier transport performance hinders the efficiency improvement. Herein, the use of additive 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) not only plays the role of passivating defects and assisting film formation but also regulates one to obtain more favorable interfacial energy band bending and energy level matching, while forming charge transfer complexes with perovskites due to its strong electron-withdrawing ability. Having all these functions at the same time makes CPSCs with F4TCNQ addition obtain high quality, low defect density films with suppressed non-radiative recombination, along with extremely fast carrier separation and extraction capabilities. Together with the optimization of the electron transport layer, the prepared CPSCs obtained an enhanced photovoltaic conversion efficiency of 15.1% and a VOC of 1.07 V with long stability.

Soft thermotropic liquid crystals (TLCs) have advantages on processability and shape memory compared to hard solids and fluids. The development of photoswitchable soft TLCs based on biomolecules would afford reworkable shape information recording biomaterials for the areas requiring biocompatibility and degradability. In recent years, anhydrous DNA TLCs composed of DNA and ammonium surfactants have been receiving continuous attention. However, the photoswitchable phase transition has not been realized for soft DNA TLCs at room temperature, owing to the absence of functional ammonium surfactant. Herein, a new type of azobenzene-containing surfactant would be applied to the fabrication of soft DNA TLCs with photoresponsive physical properties. The double-chain design of the used surfactant and the use of DOAB as a dopant guarantee the soft state of DNA TLCs at r.t., which also facilitates the azobenzene isomerization by reducing the packing density of surfactants. With the assistance of photoisomerization of azobenzene, the reported DNA TLCs achieve reversible liquid crystal-isotropic liquid transition at temperatures below clearing points even at room temperature. The repeatable shape information recording and self-erasing tests indicate these DNA TLCs would be good shape information recording biomaterials in the future. This work also provides a useful strategy for designing photoresponsive soft biomaterials based on rigid biomolecules like DNA., Graphical abstract A new type of azobenzene-containing surfactant with good water solubility and flexibility is designed and synthesized for the fabrication of soft DNA thermotropic liquid crystals. By gaining reversible isothermal phase change ability at room temperature, the developed DNA materials exhibit effective shape information recording and self-erasing properties.Image 1

Two films were prepared from single component monomer solutions. In these monomers, diacetylene and two acid groups are licked by flexible side chains. The side chain serves as the spacer between diacetylenes. After UV-irradiation, monomer films were transformed to polydiacetylene films and one of films exhibited conductivity drastically increases. This conductivity is two orders of magnitude greater than the conductivity value of reported nondoped polydiacetylene films.

Adaptive Rear-lighting System (ARS) in stoplight has been widely used in various vehicles to catch following drivers' attention with special information about light brake, heavy brake and slamming ...

We report a low-cost and effective technique for preparing borax from boron-bearing tailings, which is at a low grade of 9.98% B2O3. Well-crystallized borax is achieved by the removal of impurity, evaporation and concentration through the efficient method of sodium roasting and pressure leaching. The morphology, composition and structure of borax are investigated in this study. The result of scanning electron microscopy shows that the crystals obtained are cube-shaped with smooth surface and of good growth. The crystals are proven to be Na2B4O7·10H2O by EDS, XPS, XRD and ICP-AES. Moreover, the recovery rate of boron can reach 63.49%. This cost-effective strategy of preparing borax from boron-bearing tailings provides a guideline for the development of the boron industry and has a great potential for the commercialization of borax production.

We have systematically investigated the temperature-dependent device performance of organic photovoltaic (OPV) cells based on a squaraine dye. The 2,4-bis[4-( N , N -diisobutylamino)-2,6-dihydroxyphenyl] squaraine:[6,6]-phenyl C 71 butyric acid methyl ester (DIBSQ:PC 70 BM) OPV devices were fabricated and characterized under 100 mW cm −2 (AM1.5G solar spectrum) in a temperature range from 285 to 360 K. The temperature-dependent photovoltaic parameters such as open-circuit voltage ( V oc ), short-circuit current density ( J sc ), fill factor (FF) and power conversion efficiency (PCE) were studied in detail. The increasing temperature led to an improvement of J sc and FF, which should be ascribed to the enhanced carrier mobilities and improved electrode/active layer contact thus the improvement of photocurrent extraction at an elevated temperature. However, the V oc decrease in the same period due to the carrier recombination of the OPV device. The increase in the J sc and FF overtakes the decrease in the V oc with increasing temperature, resulting in a significantly improved PCE at elevated temperature. This study indicated that the DIBSQ based BHJ cells has promising potential for the practical application under changeable temperature environment.

We have developed a novel organic–inorganic hybrid color conversion electrode composed of Ag NWs/poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) via a solution process, which is the first report on a color conversion electrode for applications in flexible optoelectronics. Using the Ag NWs/MEH-PPV composite film as the anode on polyethylene terephthalate substrate and combined with a blue organic light emitting devices (OLEDs) unit employing bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III)) (Flrpic) in 1,3-bis(carbazol-9-yl)benzene (mCP) as the emitting layer, a highly efficient and chromaticity-stable color-conversion flexible white OLEDs (WOLEDs) is achieved with a maximum current efficiency of 20.5 cd A−1. To the best of our knowledge, this is the highest efficiency reported for color-conversion based flexible WOLEDs. Our work provides an approach to achieving high-performance flexible WOLEDs devices and demonstrates great potential for lighting and display applications.

Organic light-emitting diodes (OLEDs) have great potential applications in display and solid-state lighting. Stability, cost and high operational efficiency are key issues governing the future commercial application of OLEDs. In this context, searching for multifunctional emitting materials with acceptable light-emitting and charge-transporting characteristics has gained increasing attention. For achieving high-performance and low-cost OLEDs, the suitable molecular design featured with different electronic and optical nature should be incorporated by combining the advantages of both functional units into the same molecules. This review highlights recent and current advances in developing bifunctional or multifunctional molecules, with the focus on structures, properties, and applications in OLEDs and organic laser.

Top-emission flexible organic light-emitting devices (TE-FOLEDs) are highly suitable for next generation display due to their numerous assets including top-emitting configuration and mechanical flexibility. One major challenge in TE-FOLEDs is to prepare a deformable and reflective bottom electrode capable of effective carrier injection. In this paper, a new strategy for efficient and foldable TE-FOLEDs is demonstrated. It is based on a highly conductive Ag-nanoparticles (Ag-NPs) modified graphite that is used as a flexible bottom electrode. The good reflectance to full-color emission (>59% over the whole visible wavelength range), ultralow sheet resistance (

Stainless steel fibers (SSFs) were added into reactive powder concrete (RPC) to fabricate aligned (improved by L-shaped device) and random directional distributed SSFs conductive RPC. The aspect ratio of SSFs ranged from 30 to 150, while the SSFs amount was 0.2%–1.2% by volume of RPC. Curing ages for RPC ranged from 7 d to 60 d. The conductive performances (electrical resistance and AC impedance spectroscopy), the speed of ultrasonic passing through specimens and the following piezoresistivity were investigated. Moreover, the compressive strength, flexural strength and toughness of specimens cured for 60 d were tested. Finally, high-resolution images of SSFs’ dispersion and orientation were gained. Results showed that the ultrasonic velocity and electrical resistance of SSFs-RPC grew in the form of a quadratic function with the increasing curing ages. The SSFs content of 0.4% was the percolation threshold value of SSFs-RPC. Additionally, RPC with higher aspect ratio and aligned fibers performed better conductivity, piezoresistivity and mechanical performance. The conductive mechanism of SSFs-RPC can be explained through the conduction models of three series connected electrical components. The image analysis showed that SSFs with higher aspect ratio dispersed more uniformly in RPC and the L-shaped device could effectively improve the alignment of fibers.

A new terpyridine-based compound of 2,2′,7,7′-tetra([2,2':6′,2″-terpyridin]-4′-yl)-9,9′-spirobi[fluorene] (4oTPSF) was designed and synthesized as the electron transporter in organic light-emitting diodes (OLEDs). 4oTPSF exhibited excellent thermal stability with high glass transition temperature (Tg) of 250 °C and melting temperature (Tm) of 460 °C during the thermal measurement. The excellent thermal stability is attributed to the molecular structure, that the steric effect of rigid twisted spirobiflourene and the connected terpyridine (TPY) resulted in a decrease of the intermolecular π-stacking interaction. The studies on electrical characteristics of electron-only devices revealed that 4oTPSF showed high electron-transporting capability, as good as the conventional electron-transporting material (ETM) 1,3,5-tris(N-phenylbenzimid-azol-2-yl-benzene (TPBi). A series of green phosphorescent OLEDs (PhOLEDs) based on bis(2-phenylpyridine)iridium(III)(2,2,6,6-tetramethylheptane-3,5-diketonate) (Ir(ppy)2tmd) or tris[2-(p-tolyl)pyridine]iridium(III) (Ir(mppy)3) as emitter and 4oTPSF as ETM displayed a turn-on voltage of 2.23 V and a maximum power efficiency of 97.8 l m/W and a half-life (T50) of 101, 5680 and 319 390 h at an initial luminance of 10 000, 1000 and 100 cd/m2, respectively. The lifetime of 4oTPSF-based device was twice more than the lifetime of TPBi-based device.

This paper investigates the compressive strength loss of wollastonite modified magnesium ammonium phosphate cement (MAPC) and magnesium potassium phosphate cement (MKPC) paste after exposure to NaCl freeze-thaw cycles, alternation of dry-wet (water medium and 3 % NaCl medium), H2SO4 and NaOH corrosion. The compressive strength loss was applied to characterize the corrosion degree of specimens. Results indicated that the addition of wollastonite has a positive effect on the resistance to NaCl freeze-thaw cycles, alternation of dry-wet, H2SO4 and NaOH corrosion. The number of NaCl freeze-thaw cycles, alternation of dry-wet and the immersing days in H2SO4 and NaOH solutions led to the acceleration of corrosion. NaCl freeze-thaw cycles and alternation of dry-wet had a little corrosive effect on the wollastonite modified magnesium phosphate cement (MPC) pastes. However, wollastonite modified MPC pastes were seriously corroded by the immersion of H2SO4 and NaOH solution. MKPC showed the lower compressive strength loss when the samples were exposed to NaCl freeze-thaw cycles and dry-wet cycles in NaCl solution. While, in the condition of dry-wet cycles in water, MAPC behaved a lower compressive strength loss. Additionally, MAPC performed a higher compressive strength loss in H2SO4 corrosion environment than that of MKPC. On the other hand, MKPC showed better resistance to compressive strength attenuation.

Intermolecular interactions arise from molecular aggregation and cause concentration quenching and excimer emission. Although aggregation or excimer induced emission are sometimes favored, for example for colour tuning, intermolecular interactions should usually be minimized because concentration quenching and excimer emission usually result in poor efficiency and colour instability. In this paper, two novel tert-butyl modified naphthyl derivates, 4,5′-di-{[N,N,N′,N′- tetrakis-(4-tert- butyl-phenyl)]phenyl-1″,4‴-diamine}-1,1′-binaphthalenyl (BN5) and 1,5-di-{[N,N,N′, N′-tetrakis-(4-tert-butyl-phenyl)]phenyl-1″,4‴-diamine}-3,7-bi-tertbutylnaphthalenyl (BN6), have been synthesized and their intriguing photophysical properties and high-efficiency deep-blue electroluminescence (EL) in less-concentrated condensed phase were investigated. Electroluminescent devices based on BN5 in 50% matrix achieved a high external quantum efficiency (EQE) of 3.7% and the Commission Internationale de L'Eclairage (CIE) coordinates of (0.160, 0.081) which is very close to the National Television Standards Committee's (NTSC of USA) pure blue standard. Meanwhile, the non-doped device based on BN5 demonstrated a much higher EQE of 4.5%. Neat BN6-based device presented a pure monomer emission (λpeak = 420 nm) with an extremely high EQE of 5.1% and a satisfactory CIE coordinate of (0.171, 0.076). Such values are the best ever reported for 420 nm EL emission with an un-doped layer. We attributed the enhanced performance of deep blue monomer light-emitting diodes to tert-butyl groups of BNs due to a reduction of intermolecular interaction, especially the tert-butyl substituents on the molecular backbone of BN6 play a major role in inhibiting dimer and crystallization-induced emission.

International audience; In this work, an atomic layer deposited (ALD) $Al_{2}$$O_{3}$ ultrathin layer was introduced to passivate the ZnO-nanoparticle (NP) buffer layer of inverted polymer solar cells (PSCs) based on P3HT:PCBM. The surface morphology of the ZnO-NP/$Al_{2}$$O_{3}$ interface was systematically analyzed by using a variety of tools, in particular transmission electron microscopy (TEM), evidencing a conformal ALD-$Al_{2}$$O_{3}$ deposition. The thickness of the $Al_{2}$$O_{3}$ layers was optimized at the nanoscale to boost electron transport of the ZnO-NP layer, which can be attributed to the suppression of oxygen vacancy defects in ZnO-NPs confirmed by photoluminescence measurement. The optimal inverted PSCs passivated by ALD-$Al_{2}$$O_{3}$ exhibited an ~22% higher power conversion efficiency than the control devices with a pristine ZnO-NP buffer layer. The employment of the ALD-$Al_{2}$$O_{3}$ passivation layer with precisely controlled thickness provides a promising approach to develop high efficiency PSCs with novel polymer materials.

Damaged cartilage has poor self-healing ability and usually progresses to scar or fibrocartilaginous tissue, and finally degenerates to osteoarthritis (OA). Here we demonstrated that one of alternative isoforms of IGF-1, mechano growth factor (MGF) acted synergistically with transforming growth factor β3 (TGF-β3) embedded in silk fibroin scaffolds to induce chemotactic homing and chondrogenic differentiation of mesenchymal stem cells (MSCs). Combination of MGF and TGF-β3 significantly increased cell recruitment up to 1.8 times and 2 times higher than TGF-β3 did in vitro and in vivo. Moreover, MGF increased Collagen II and aggrecan secretion of TGF-β3 induced hMSCs chondrogenesis, but decreased Collagen I in vitro. Silk fibroin (SF) scaffolds have been widely used for tissue engineering, and we showed that methanol treated pured SF scaffolds were porous, similar to compressive module of native cartilage, slow degradation rate and excellent drug released curves. At 7 days after subcutaneous implantation, TGF-β3 and MGF functionalized silk fibroin scaffolds (STM) recruited more CD29+/CD44+cells (P

This paper demonstrates the lasing and transport properties of a green conjugated polymer, namely POFP. High photoluminescence yields and excellent electron transport of POFP film make it promising for gain media. Low threshold value of 4.0 μJ/cm2 for amplified spontaneous emissions under a pulsed Nd:YAG laser at 355 nm was obtained, as well as a high Q-factor of 159. An inverted waveguide microcavity scheme has been developed to fabricate diode-pumped organic solid lasers (OSLs) using POFP. Gain narrowing with significant radiance increase was observed in the devices, giving evidence of the interference enhancement induced by microcavity and the lasing properties of POFP. Electronic supplementary material The online version of this article (10.1186/s11671-017-2371-7) contains supplementary material, which is available to authorized users.

The technique of organic light-emitting diodes developed rapidly over the last decade and small size OLED panels has also been commercially applied. However, organic semiconductors exhibit relatively poor electrical and thermal behavior and the device stability is always a tough issue since the high sensitivity to the environment, such as the water, oxygen, temperature, and so on. Therefore, the organic-inorganic hybrid light-emitting devices become research focus for combining both the high electron mobility of inorganic semiconductors and the extraordinary optoelectronic properties of polymers. However, according to previous research results, there are still problems such as low brightness, poor color rendering, low efficiency and low current density etc. Here, we present a novel inverted organic-inorganic hybrid blue fluorescent device with the hybrid p-n junction structure using n-type GaN (n-GaN) and organic semiconductor layers, which was proved to have extremely high luminance and low driving voltage. Single layer n-GaN with thickness of 2.5 um on patterned sapphire substrate (PSS) was used in this paper because it has excellent electrical conductivity and outstanding thermal conductivity. Based on this organic-inorganic hybrid system, we have proved a high-brightness and low turn-on voltage light-emitting devices.

Small-diameter synthetic vascular grafts have high failure rate and tissue-engineered blood vessels are limited by the scalability. Here we engineered bioactive materials for in situ vascular tissue engineering, which recruits two types of endogenous progenitor cells for the regeneration of blood vessels. Heparin was conjugated to microfibrous vascular grafts to suppress thrombogenic responses, and stromal cell-derived factor-1α (SDF-1α) was immobilized onto heparin to recruit endogenous progenitor cells. Heparin-bound SDF-1α was more stable than adsorbed SDF-1α under both static and flow conditions. Microfibrous grafts were implanted in rats by anastomosis to test the functional performance. Heparin coating improved the short-term patency, and immobilized SDF-1α further improved the long-term patency. SDF-1α effectively recruited endothelial progenitor cells (EPCs) to the luminal surface of the grafts, which differentiated into endothelial cells (ECs) and accelerated endothelialization. More interestingly, SDF-1α increased the recruitment of smooth muscle progenitor cells (SMPCs) to the grafts, and SMPCs differentiated into smooth muscle cells (SMCs) in vivo and in vitro. Consistently, SDF-1α-immobilized grafts had significantly higher elastic modulus. This work demonstrates the feasibility of simultaneously recruiting progenitor cells of ECs and SMCs for in situ blood vessel regeneration. This in situ tissue engineering approach will have broad applications in regenerative medicine.

Polymeric carbon nitride (CNxHy) has been facilely synthesized from dicyandiamide and functions as a solution-processed hole injection layer in organic light-emitting diodes (OLEDs). The measurements using X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and impedance spectroscopy elucidate that CNxHy exhibits superior film morphology and extra electric properties such as tailored work function and tunable hole injection. The luminous efficiency of CNxHy-based OLED is found to improve by 76.6% in comparison to the counterpart using favorite solution-processed poly(ethylene dioxythiophene):poly(styrene sulfonate) as the hole injection layer. Our results also pave a way for broadening carbon nitride applications in organic electronics using the solution process.

In many 2D materials reported thus far, the forces confining atoms in a 2D plane are often strong interactions, such as covalent bonding. Herein, the first demonstration that hydrogen (H)-bonding can be utilized to assemble polydiacetylene (a conductive polymer) toward a 2D material, which is stable enough to be free-standing, is shown. The 2D material is well characterized by a large number of techniques (mainly different microscopy techniques). The H-bonding allows splitting of the material into ribbons, which can reassemble, similar to a zipper, leading to the first example of a healable 2D material. Moreover, such technology can easily create 2D, organic, conductive nanowire arrays with sub-2-nm resolution. This material may have potential applications in stretchable electronics and nanowire cross-bar arrays.

Tissue-specific stem cells can be coaxed or harvested for tissue regeneration. In this study, we identified and characterized a new type of stem cells from the synovial membrane of knee joint, named neural crest cell-like synovial stem cells (NCCL-SSCs). NCCL-SSCs showed the characteristics of neural crest stem cells: they expressed markers such as Sox10, Sox17 and S100β, were clonable, and could differentiate into neural lineages as well as mesenchymal lineages, although NCCL-SSCs were not derived from neural crest during the development. When treated with transforming growth factor β1 (TGF-β1), NCCL-SSCs differentiated into mesenchymal stem cells (MSCs), lost the expression of Sox17 and the differentiation potential into neural lineages, but retained the potential of differentiating into mesenchymal lineages. To determine the responses of NCCL-SSCs to microfibrous scaffolds for tissue engineering, electrospun composite scaffolds with various porosities were fabricated by co-electrospinning of structural and sacrificial microfibers. The increase in the porosity in microfibrous scaffolds enhanced cell infiltration in vitro and in vivo, but did not affect the morphology and the proliferation of NCCL-SSCs. Interestingly, microfibrous scaffolds with higher porosity increased the expression of chondrogenic and osteogenic genes but suppressed smooth muscle and adipogenic genes. These results suggest that the differentiation of NCCL-SSCs can be controlled by both soluble chemical factors and biophysical factors such as the porosity of the scaffold. Engineering both NCCL-SSCs and scaffolds will have tremendous potential for tissue regeneration.