NONLINEAR J-E CHARACTERISTICS IN THE ELECTRIC-THERMAL EQUILIBRIUM STATE FOR HIGH DENSITY POLYETHYLENE CONDUCTIVE COMPOSITES

The nonlinear J-E characteristics under self-heating equilibrium for conductive composites based on high density polyethylene were studied. The results show that there are identical conduction mechanisms under self-heating equilibrium for the composites with various initial resistivities determined by filler content or ambient temperature. The nonlinear conduction behavior was involved in the limited microstructure transformations of the conducting network induced by electrical field applied and the corresponding self-heating effect. A reversible thermal fuse (RTF) model was suggested to interpret the physical origin of the nonlinear J-E characteristics.

PREPAKATION OF THERMALLY REVERSIBLE HYDROGELS AND THEIR USE FOR THE IMMOBILIZATION OF CHYMOTRYPSIN

A series of hydrogels with lower critical solution temperature (LCST) were prepared and used for the immobilization of chymotrypsin. The activities of the immobilized enzyme decrease when the temperatures are raised above their LCST and recover below their LCST. This property is reversible.

Phase transformation and crystal growth behavior of 8mol%(SmO1.5, GdO1.5, and YO1.5) stabilized ZrO2 powders

Nanocrystalline powders of ZrO_2–8mol%SmO1.5（8Sm SZ）, ZrO_2–8mol%GdO1.5（8Gd SZ）, and ZrO_2–8mol%YO1.5（8YSZ） were prepared by a simple reverse-coprecipitation technique. Differential thermal analysis/thermogravimetry（DTA/TG）, Fourier transform infrared spectroscopy（FTIR）, X-ray diffraction（XRD）, Raman spectroscopy, and high-resolution transmission electron microscopy（HRTEM） were used to study the phase transformation and crystal growth behavior. The DTA results showed that the ZrO_2 freeze-dried precipitates crystallized at 529, 465, and 467°C in the case of 8Sm SZ, 8Gd SZ, and 8YSZ, respectively. The XRD and Raman results confirmed the presence of tetragonal ZrO_2 when the dried precipitates were calcined in the temperature range from 600 to 1000°C for 2 h. The crystallite size increased with increasing calcination temperature. The activation energies were calculated as 12.39, 12.45, and 16.59 k J/mol for 8Sm SZ, 8Gd SZ, and 8YSZ respectively.

Poly-N-Isopropylacrylamide Hydrogel Based Fluoroimmunoassay of Methyltestosterone

A novel immunoassay method for methyltestosterone (MT) in serum ovas developed.The antigen of MT (Ag(MT))was synthesized by covalently bonding MT to BSA and raising its antibody (Ab(MT)). Ab(MT) was con.jugated to poly-N-isopropylacrylamide (p-NIPAAm) to form Ab(MT) bound thermally reversible hydrogel p-NIPAAm-Ab((MT) A competitive immunoassay method based on the competition of fluorescein isothiocyanate (FITC) labeled MT antigen (FITC-Ag(MT)) and free MT with limited amount of p-NIPAAm-Ab(MT) was established. The separation in the assay process was achieved by precipitation of the immuno-complex above its critical solution temperature. The detection limit for MT is 50ng/ml. The recoveries of MT from human serum are satisfactory.

Analysis on the Characteristic Properties of PEDOT Nano-particle Based on Reversed Micelle Method

Based on the study of a new type of conducting polymer poly （3,4-ethylenedioxythiophene） （PEDOT）,we focussed on the preparation and characteristics of PEDOT nanoparticles made by reversed micelle method.Moreover,we deeply investigated the optical,electrical and the thermal stability of PEDOT nanoparticles.The main results are as follows： the small-sized PEDOT nanoparticles were prepared and utilized by different methods,such as ultraviolet/visible （UV-Vis） spectroscopy,Fourier-transform infrared （FT- IR） spectrum,scanning electron microscopy（SEM） and so on.The results show that the amount of oxidizer,ultrasonic treatment,polymerizing temperature and doping degree can influent morphology,electrical ability and gas sensitivity of PEDOT nanoparticles.The Bragg peaks of nanoparticles at 6.7°,12.7°,25° were observed by XRD and the better orientation of molecular chain was attributed to the effective doping of toluene-p-sulfonic acid,which also resulted in an enhancement of thermal stability of nanoparticles than conventional PEDOT.

Thermal Reversion of Plant Phytochromes

Phytochromes are red/far-red reversible photoreceptors essential for plant growth and development.Phytochrome signaling is mediated by the physiologically active far-red-absorbing Pfr form that can be inactivated to the red-absorbing Pr ground state by light-dependent photoconversion or by light-independent thermal reversion,also termed dark reversion.Although the term“dark reversion”is justified by historical reasons and frequently used in the literature,“thermal reversion”more appropriately describes the process of light-independent but temperature-regulated Pfr relaxation that not only occurs in darkness but also in light and is used throughout the review.Thermal reversion is a critical parameter for the light sensitivity of phytochrome-mediated responses and has been studied for decades,often resulting in contradictory findings.Thermal reversion is an intrinsic property of the phytochrome molecules but can be modulated by intra-and intermolecular interactions,as well as biochemical modifications,such as phosphorylation.In this review,we outline the research history of phytochrome thermal reversion,highlighting important predictions that have been made before knowing the molecular basis.We further summarize and discuss recent findings about the molecular mechanisms regulating phytochrome thermal reversion and its functional roles in light and temperature sensing in plants.

Novel thioxanthone host material with thermally activated delayed fluorescence for reduced efficiency roll-off of phosphorescent OLEDs

2,7-Di（9,9-dimethyl-9H-fluoren-l-yl）-9H-thioxanthen-9-one （DMBFTX） with thermally activated delayed fluorescence （TADF） was well designed and synthesized. The phosphorescent organic lightemitting device （PHOLED） based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency （EQE） value of 12.9% and a low EQE roll-off of 38.8%at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing （RISC） of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFrX exhibits superior electroluminescence performance and reduced efficiency roll-offcompared with the one hosted by commercially available host 1,3-bis（9-carbazolyl）benzene （mCP）, illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.

Design and synthesis of self-healing polymers

Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.