Temperature Dependence of the Mössbauer Effect on Prussian Blue Nanowires

Highly ordered Prussian blue nanowires with diameter of about 50 nm and length up to 4 m have been fabricated by an electrodepositing technology with two-step anodizing anodic aluminum oxide films. The Mössbauer spectra taken between 15 and 300 K indicate that the hyperfine parameters decrease as the temperature increases. The temperature dependence of the quadrupole splitting, the isomer shift and the spectra area are discussed. A decrease of Debye temperature for Prussian blue nanowires was found with respect to that of Prussian blue bulk.     

Heating-induced micelle to vesicle transition in the cationic-anionic surfactant systems: Comprehensive study and understanding

Heating-induced micelle to vesicle transition (MVT), which has been rarely reported in surfactant systems, was systemically studied in a number of mixed cationic-anionic surfactant systems. According to the turbidity measurements, the investigated systems can be divided into two classes: Class A and B. Heating-induced MVT was observed in Class A at certain total surfactant concentrations and mixed surfactant ratios, while no such transition was found in Class B. Further investigations revealed that the heating-induced MVT is more likely to take place in the cationic-anionic surfactant systems with relatively stronger molecule interaction and larger micelle aggregation number. The effects of several physicochemical factors, such as the variation of mixed surfactant ratios and the addition of n-decanol on the heating-induced MVT, were also studied.     

内腔自适应光学系统校正激光器畸变

固体激光器中,增益介质由于热沉积产生的热畸变严重影响了激光器的稳定性、输出功率和光束质量。研究了一种内腔自适应光学系统校正激光器腔内畸变的方法,利用微机电变形反射镜作为固体激光器的内腔全反射镜,通过控制变形镜的面型改善激光器输出光束的模式及功率。从腔外引入的一束信标光通过激光器内腔后反射出腔外,用波前探测器可测得激光器工作时腔内畸变对此信标光的影响,并通过搭建的自适应光学系统平台可闭环校正此畸变。实验结果表明,闭环校正后,激光器的输出功率提高了近3倍,且激光光束质量得到了明显的改善。     

Polyvinylidene fluoride/polystyrene hybrid fibers with high ionic conductivity and enhanced mechanical strength as lithium-ion battery separators

Journal of Solid State Electrochemistry - Ionic conductivity is an important separator parameter influencing the cycle life and rate capability of lithium-ion batteries (LIBs). To improve the ionic...     

Bipolar copolymers comprised mesogen‐jacketed polymer containing oxadiazole units and PVK as host materials for electroluminescent devices

Nonconjugated bipolar transport polymers have been developed as host materials for electroluminescent devices by incorporating both electron‐transporting and hole‐transporting functionalities into copolymers. The random copolymer PCt‐nvk3‐7 containing mesogen‐jacketed segment of P‐Ct have been synthesized and characterized. The effect of mesogen‐jacketed segment content of these bipolar copolymers on device performance has been investigated. The results of polymer light‐emitting diodes (PLEDs) show that the jacketed content of copolymers has a significant effect on device performance: lowering charge transport and facilitating the hole‐electron recombination leads to much higher current efficiency. Applying these high triplet random copolymers as host, the maximum current efficiency of 0.70 cd/A and the maximum brightness of 1872.8 cd/m² was achieved for PCt‐nvk3‐7 with an orange‐emitting complex dopant. The results suggest that the bipolar copolymers PCt‐nvks can be good host polymers for electrophosphorescent devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7861–7867, 2008     

Fabrication of hollow and mesoporous germania microspheres by templating against plasma-treated polystyrene microspheres

The surfaces of monodisperse polystyrene (PS) colloids have been modified with hydroxyl groups by means of plasma treatment technique. By templating against these surface-modified PS colloids, the germania coating PS composite microspheres were prepared via a sol–gel process. After removal of PS cores, the resulting composite microspheres converted into hollow germania microspheres with mesoporous structure. The shell thickness of these hollow spheres can be controlled by varying the concentration of germania precursor. BET results indicated that the hollow germania microspheres shell exhibits slightly broader pore size distribution than that of corresponding composite one owing to the swelling effects of the PS core during the etching process. In addition, the as-prepared germania exhibits amorphous phase which can be converted into crystalline phase by calcination treatment. It is worthy to noting that this fabrication protocol demonstrated a facile, low-cost and environment-benign way for fabricating hollow germania structures by templating method. Moreover, this protocol is not limit to germania; it also could be used to create the other hollow inorganic oxides spheres.     

Tunable optical transmission through square-core metallic nanotube arrays

We propose a square-core metallic nanotube array and investigate its optical transmission property theoretically. We find that the transmission spectra can be tuned by the width of square-core edge, the intertube spacing and the dielectric constants of the core and the embedding medium between the nanotubes. We show that there is a band gap over a wide optical wavelength, and its width, number and position are sensitive to the tunable parameters. We also discuss the situation of the rectangular-core nanotube arrays and present that modification of the size of internal holes leads to redshift of the transmission spectra. Based on the localized nature of the field distributions, we show that there are local plasmonic resonant modes that originate from multipolar plasmon polaritons and a large number of opposing surface charges build up in the gap between adjacent nanotubes.     

Surface plasmon tunneling through a touching gold nanocylinder array on a thin gold film

The optical property of a structure composed of a touching gold nanocylinder array on a thin gold film is investigated using finite-difference time-domain (FDTD) method. It is discovered that the transmission behavior can be tuned by tuning the geometry of the structure. As the film thickness increases, the transmission mode associated with the localized surface plasmon resonance blue shifts accompanied with a decrease of magnitude and full width at half maximum, and a second transmission appear due to the interaction of the plasmons on the cylinder with their images induced on the film. The localized waveguide resonance diminishes but the second resonance peak is intensified and broadened noticeably with the separation of the cylinder array and film increase. The cylinder radius size influences the localized surface plasmon resonance mode obviously. These results may be helpful for the design of a novel optical device.     

Distribution of samarium and ytterbium in rats measured by enriched stable isotope tracer technique and INAA

In the present study a method using enriched stable isotope tracer and instrumental neutron activation analysis (INAA) was developed to study the dynamic distribution of rare earth elements (REEs) in a variety of organs and tissues of Wistar rats. Stable isotopes ¹⁵²Sm and ¹⁶⁸Yb were selected as tracers for the experiment. Intravenously injected ¹⁵²Sm and ¹⁶⁸Yb in chloride form could be quickly absorbed and distributed in almost all the organs and tissues of interest, including liver, skeleton, kidney, spleen, heart, lung, testicle, and blood serum. Liver and skeleton had high ability to take up ¹⁵²Sm and ¹⁶⁸Yb under the experimental conditions, whereas the contents of the elements in other organs were generally lower than 2% of the given dose during the whole experimental period. The difference in distribution of ¹⁵²Sm and ¹⁶⁸Yb in the body was also discussed.