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The blend fibrous membranes with the different mass ratio of silk fibroin (SF) powder to polyurethane (PU) were fabricated by electrospinning. The structure, morphology, mechanical properties, and surface wettabilities of the blend fibrous membrane are characterized by field-emission scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, dynamic mechanical thermal analysis, tensile testing, and contact angle measurements. The results show that the SF was uniformly distributed in the blend fibers. The mass ratio of SF to PU played an important role in influencing the structure and morphology of the blend fibers, and the optimum mass ratio was 5/5. With the increase in SF content in fibers, the fraction of SF in the surface of the SF/PU blend fibers and the crystallinity degree of PU increased, and the molecular orientation of PU along the fiber axis took place. The SF content regulated the hydrophilicity property of the membrane. The thermal stability and the dynamic storage modulus of the fibrous membrane decreased, and the phase separation between soft and hard segments of PU increased. Similarly, the stress at peak and Young's modulus of the fibrous membrane decreased gradually; the strain at peak first increased and then decreased. POLYM. ENG. SCI., 52:2025-2032, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION Considerable efforts to develop scaffolds for tissue engineering have been attempted using biodegradable and biocompatible polymers over the last decade. Principally, the scaffold should be designed by mimicking the [...]

The molecular structures and absorption spectra of three tetrahydroquinoline dyes (C2-1, C1-1, and C1-5) with a tetrahydroquinoline moiety as the electron donor, a cyanoacrylic acid moiety as the electron acceptor, and different thiophene-containing electron spacers were investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The calculated geometries indicate that a strong conjugation is formed in the dyes and the conjugate length increases with the increase of spacer length. The interfacial charge transfer between the semiconductor electrode and the tetrahydroquinoline dyes are electron-injection processes from the excited dyes to the semiconductor conduction band. The simulated absorption bands are assigned to π-π* transitions, which exhibit appreciable red-shift with respect to the experimental bands owing to the lack of direct solute-solvent interaction and the inherent approximations in TD-DFT. Moreover, the effect of different spacers on the molecular structures, absorption spectra, and photovoltaic performance were comparatively discussed. Key words: tetrahydroquinoline dyes, dye-sensitized solar cells, density functional theory (DFT), molecular structures, absorption spectra. Faisant appel a la theorie de la fonctionnelle de la densite (TFD) et a la TFD avec dependance sur le temps (TFD-DT), on a calcule les structures moleculaires et les spectres d'absorption de trois colorants a base de la tetrahydroquinoleine (C2-1, C1-1etC1-5) comportant une portion tetrahydroquinoleine comme donneur d'electron, une chaine d'acide cyanoacrylique comme accepteur d'electron et divers groupes d'espacement d'electrons contenant du thiophene. Les geometries calculees indiquent qu'il se forme une forte conjugaison dans les colorants et que la longueur conjuguee augmente avec une augmentation de la longueur de l'espaceur. Le transfert de charge interfacial entre l'electrode du semiconducteur et les colorants a base de tetrahydroquinoleine sont des processus d'injection d'electron des colorants excites vers la bande de conduction du semiconducteur. Les bandes d'absorption simulees sont attribuees aux transitions π-π* qui presentent un deplacement appreciable vers le rouge par rapport aux bandes experimentales en raison du manque d' interaction directe solute solvant et des approximations inherentes a la methode (TFD-DT). On discute de plus de l'effet des divers groupes d'espacement sur les structures moleculaires, sur les spectres d'absorption et sur la performance photovoltaique. Mots-cles : colorants de la tetrahydroquinoleine, cellules solaires sensibilisees par des colorants, theorie de la fonctionnelle de la densite, structures moleculaires, spectres d'absorption. [Traduit par la Redaction], Introduction Nanocrystalline dye-sensitized solar cells (DSSCs) have attracted much attention as promising alternatives for the photovoltaic conversion of solar energy owing to their potentially low fabrication costs, environmentally friendly components, [...]

Continuous real-time human motion and heart-rate monitoring systems can provide vital clinical information for disease diagnosis, preventive healthcare and rehabilitation care. However, it is still a challenge to design wearable pressure/strain sensors with great flexibility and sustainable power for motion detection and physiological signal monitoring. Here, a self-powered laminated fabric sensor based on Schottky contact was successfully fabricated. This laminated fabric sensor was constructed by sandwiching the polypyrrole (PPy)-coated fabric with the Ni-coated fabric and Al plastic film. The electrical outputs under strain were attributed to the single Schottky contact between PPy and Al. This fabric sensor exhibited excellent stability under continuous quick cycling operation and at high relative humidity, which could be adapted to different human body parts for continuous motion detection and heart-rate monitoring. This work is of great significance to demonstrate a promising strategy toward self-powered wearable pressure sensors used for human motion detecting and hear-rate monitoring. [ABSTRACT FROM AUTHOR]