A series of well-defined 9,9′-dihexylfluorene-co-fluorenone copolymers with various fluorenone contents and a set of monodisperse oligofluorenes in the chain center have been developed through the palladiumcatalyzed Suzuki coupling reaction. The structure-property relationships, especially the effect of fluorenone moieties on the photophysical and electroluminescent properties of these materials, are systematically investigated to elucidate the exact origin of the low-energy emission in polyfluorenes. On the basis of our substantial studies of the steady-state photoluminescence (PL) and PL decay dynamics of the fluorenone-containing oligomers and copolymers both in dilute solutions and in thin films, the origin of the controversial low-energy emission band might be due to the interaction between intrachain fluorenone moieties in polyfluorenes instead of the intermolecular aggregates or excimers. We further show that fluorene pentamer with a central fluorenone unit (oligomer 2) is more appropriate to represent the actual chromophore responsible for the green emission in the copolymers. The green emission of the copolymers in the solid states is well described by single-exponential decay and has a lifetime ranging from 4.21 to 8.15 ns, depending on fluorenone content. The substantially enhanced intensity of the green emission with increasing the intermolecular interaction in solid states results from the contribution of both the intramolecular and the more efficient intermolecular energy transfer from the fluorene segments to fluorenone moieties. We also find that the emission wavelength and the lifetime of the green emission for the copolymer with the lowest fluorenone content (PHF-FO0.1) in solid states are very similar to those of the emerging low-energy emission for poly(9,9′-dihexylfluorene) (PDHF) after high-temperature thermal annealing in air. Bright yellow electroluminescence (EL) is achieved from double-layer LEDs based on these materials with an emission peak of 540-579 nm that steadily red-shifted with increasing fluorenone contents. The better luminance and external quantum efficiencies are probably due to improved electron injection and carrier transporting as well as efficient charge trapping and recombination at the fluorenone sites.

A novel series of naphthalimide dendrimers has been synthesized based on a convergent and divergent combined approach. The dendrimers consist of naphthalimide-based cores, Fre ´chet-type poly(aryl ether) dendrons, and carbazole (CZ) or oxadiazole (OXZ) peripheral groups. The higher generation dendrimer has site-isolation effect, or the dilution effect of the dendrons. This configuration would reduce the aggregating extent or possibility of the core unit, thus resulting in a relatively small red-shift of absorption and fluorescent spectra when they form a solid film for the applications. Studies of steadystate fluorescence properties of the dendrimers show that excitation of the terminal chromophores results mainly in the core emission alone, as the donor emission is seriously quenched due to its effective Fo ¨rster intramolecular energy transfer to the core. The dendrimers show enhanced luminescence properties of the core, and the enhanced luminescent efficiency is dependent on the generation number of the dendrimers. Time-resolved luminescent measurements further supported the conclusion that the contribution tendency for each peripheral donor is decreased with the increasing of the generation number, especially for the third generation. The dendron-incorporated carbazole unit can decrease the HOMO orbital energy by 0.4 eV, thus facilitating the hole-injection in electroluminescent (EL) devices. The preliminary EL results with a single-layer architecture made with the dendrimers by means of the spincoating technique demonstrate that these dendrimers could be utilized as promising active nondoping emitters.

This paper presents a backstepping control method for speed sensorless permanent magnet synchronous motor based on slide model observer. First, a comprehensive dynamical model of the permanent magnet synchronous motor (PMSM) in d-q frame and its space-state equation are established. The slide model control method is used to estimate the electromotive force of PMSM under static frame, while the position of rotor and its actual speed are estimated by using phase loop lock (PLL) method. Next, using Lyapunov stability theorem, the asymptotical stability condition of the slide model observer is presented. Furthermore, based on the backstepping control theory, the PMSM rotor speed and current tracking backstepping controllers are designed, because such controllers display excellent speed tracking and anti-disturbance performance. Finally, Matlab simulation results show that the slide model observer can not only estimate the rotor position and speed of the PMSM accurately, but also ensure the asymptotical stability of the system and effective adjustment of rotor speed and current.

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C1q tumor necrosis factor-related proteins (CTRPs), which are members of the adipokine superfamily, have gained significant interest in the recent years. CTRPs are homologs of adiponectin with numerous functions and are closely associated with metabolic diseases, such as abnormal glucose and lipid metabolism and diabetes. Previous studies have demonstrated that CTRPs are highly involved in the regulation of numerous physiological and pathological processes, including glycolipid metabolism, protein kinase pathways, cell proliferation, cell apoptosis and inflammation. CTRPs also play important roles in the development and progression of numerous types of tumor, including liver, colon and lung cancers. This observation can be attributed to the fact that diabetes, obesity and insulin resistance are independent risk factors for tumorigenesis. Numerous CTRPs, including CTRP3, CTRP4, CTRP6 and CTRP8, have been reported to be associated with tumor progression by activating multiple signal pathways. CTRPs could therefore be considered as diagnostic markers and therapeutic targets in some cancers. However, the underlying mechanisms of CTRPs in tumorigenesis remain unknown. The present review aimed to determine the roles and underlying mechanisms of CTRPs in tumorigenesis, which may help the development of novel cancer treatments in the future.