Synthesis and orientation study of a magnetically aligned liquid‐crystalline chitin/poly(acrylic acid) composite

A high magnetic field of 5 T was used to fabricate a magnetically aligned, optically anisotropic, liquid‐crystalline chitin/poly(acrylic acid) composite. The aligned mesophase was fixed by photoinitiated free‐radical polymerization. From an examination of polarized optical micrographs and an X‐ray diffraction study, a high degree of orientation of 0.70 was observed for the composite with a higher liquid‐crystalline chitin concentration (10.70 wt %); the orientation was reduced with a decreased chitin concentration at a given acrylic acid concentration. The X‐ray data for the developed composite showed a uniplanar orientation for the chitin crystallites, with its molecular long axes perpendicular to the direction of the magnetic field. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 711–714, 2003     

稀土离子间反斯托克斯能量传递计算的改进 1.实验及理论基础

从理论和实验上研究了红绿荧光强度反转现象。实验测量发现Er(0.5)Yb(9.5)∶FOV纳米相氟氧化物玻璃陶瓷存在强的红绿荧光强度反转现象,实验测量得到其红绿荧光强度反转动态范围为877,同时计算了Er(0.5)Yb(9.5)∶FOV的所有基础光谱参量,建立了对系统所有稀土离子能级的动力学过程进行数值模拟计算的理论基础。     

Experiments and analysis of infrared quantum cutting luminescence phenomena of Ho/Yb codoped nanophase oxyfluoride vitroceramics

The infrared quantum cutting phenomenon, which is an international hot research field, of Ho³⁺Yb³⁺: oxyfluoride vitroceramics (FOV) was studied in the present paper. It was found from the fluorescence spectroscopy experiments that the excitation spectrum of 973.0 nm fluorescence of Yb³⁺ ion is very similar to the absorption and excitation spectra of Ho³⁺ ion. It suggests that the energy transfer from Ho³⁺ ion to Yb³⁺ ion is very efficient. Then, all the possible important energy transfer passages were analyzed. It was found that the energy transfers {⁵G₄(Ho³⁺)→⁵F₅(Ho³⁺), ²F_7/2(Yb³⁺)→²F_5/2(Yb³⁺)} and {⁵F₅(Ho³⁺)→⁵I₇(Ho³⁺), ²F_7/2(Yb³⁺)→²F_5/2(Yb³⁺)} result in the effective two-photon quantum cutting 973.0 nm fluorescence of Yb³⁺ ion when ⁵G₄ or ³K₇ or the above energy level of Ho³⁺ ion are excited. Finally, the quantum efficiency η_QE,1%Yb=43.0% and η_QE,5%Yb=171.7% of two-photon quantum cutting was calculated for Ho(0.5)Yb(1):FOV and Ho(0.5)Yb(5):FOV respectively. This research would be beneficial for the enhancement of solar cell efficiency.     

Tm(0.1)Yb(10.9)氟氧化物玻璃的直接上转换敏化发光

本文首次研究了Tm(0.1)Yb(10.9)氟氧化物玻璃在966nm半导体激光激发下的直接上转换敏化发光现象。测量发现存在很强的^1G4→^3H6的474nm三光子和较弱的^1D2→^3H6的362nm,^1D2→^3F4的452nm,^1G4→^3F4的650nm三光子以及^3F3→^3H6的681nm二光子上转换发光。并对他们的上转换机理做了简要的讨论分析。     

Design and feasibility assessment of topically applied drug formulations for electroporation

Few studies have been reported on the design of topical formulations consisting of electrodes and active drugs for electroporation as a means to increase skin permeability of the drugs, although many studies were reported for the effect of this physical means using aqueous drug solutions. We, therefore, designed a prototypic reservoir and matrix topical formulations that are suitable for electroporation in the present study. Plate-plate Ag electrodes and sodium diclofenac were used as model electrodes and the drug, respectively. The in vitro skin permeations of the drug obtained from the reservoir and matrix formulations were slightly higher than that from an aqueous suspension. This may be due to slightly higher electric field in the skin barrier for the presently designed formulations than that for the aqueous suspension. The present feasibility test suggests that these reservoirs and matrix formulations are useful prototypic topical formulations for electroporation application to improve the drug permeability through skin.     

BLUE COOPERATIVE UP-CONVERSION LUMINESCENCE OF Yb3+ IONS IN OXYFLUORIDE GLASS EXCITED BY 960 nm LASER

Investigates the up-conversion luminescence of Yb-doped oxyfluoride glass excited by a 960nm-diode laser. A new up-conversion cooperative radiation luminescence is found, which is rather strong and positioned at 476.1 nm. It comes from the coupled states of two-Yb^{3+-ions cluster. It is significant because it is an effective and convenient method of producing blue light.}     

纳米相氟氧化物玻璃陶瓷Tm（0.35）Yb（5）∶FOV的上转换发光

研究了纳米相氟氧化物玻璃陶瓷Tm(0.35)Yb(5)∶FOV在975nm半导体激光激发下的上转换发光。发现了位于363.6,(462.6,477.0),648.7,(699.7,680.7)和(777.6,800.7nm)的几条上转换发光线,它们是Tm3 离子的1D2→3H6,1G4→3H6,1G4→3F4,3F3→3H6和3H4→3H6的荧光跃迁。为了确认它们的上转换机理,还测量了上转换发光强度F随975nm泵浦激光功率P改变的双对数曲线,结果证实了1D2能级的上转换发光部分是五光子上转换发光,而1G4能级和3H4能级的上转换发光则是三光子和双光子上转换发光。     

Fuzzy importance in fault tree analysis

In fault tree analysis, system success or failure can be described by the state of the top event, which is usually defined by a so-called structure function. In this paper, we attempt to simplify the calculation process of the structure function and to newly define the state of the top event by the membership function, using fuzzy sets theory. Furthermore, it is shown that the importance of each basic event can be evaluated through fuzzy operations. The method proposed herein is demonstrated by some examples with respect to the failure analysis of structures.     

Tm^3＋在氟氧化物玻璃陶瓷中的光普性质

根据Tm掺杂的氟氧化物玻璃陶瓷的吸收光谱,用Judd-Ofelt理论上计算了强度参量,并由此计算了激发能极的自发辐射跃迁几率、辐射寿命、荧光分支和积分发射截面等光谱参量。     

1 520 nm激光激发的Er(0.5):FOG材料的上转换发光与立体显示研究

立体显示为现代重要的科学前沿。上转换三维立体显示为一种新颖的自体视三维立体显示,在1996年被评为十大科技创新成就之一,现正向应用快速发展。研究了1 520 nm半导体激光激发的Er(0.5):FOG材料的上转换发光,发现了(407.43, 411.20 nm), (522.51m, 528.57 nm), (540.53m, 543.70,549.00 nm), (654.75m, 665.50 nm), 和802.10m nm的上转换发光(m代表主峰),依次为(2G4F2H)_9/2→4I_15/2, 4H_11/2→4I_15/2, 4S_3/2→4I_15/2, 4F_9/2→4I_15/2和4I_9/2→4I_15/2的跃迁。值得注意的是上转换发光强度随激光功率变化的双对数曲线的斜率有各种各样的值。通过详细研究发现(407.43, 411.20 nm)的(2G4F2H)_9/2→4I_15/2上转换发光是四光子荧光;(522.51m, 528.57 nm)的2H_11/2→4I_15/2,(540.53m, 543.70,549.00 nm)的4S_3/2→4I_15/2和(654.75m, 665.50 nm)的4F_9/2→4I_15/2的上转换发光为三光子荧光;而802.10m nm的4I_9/2→4I_15/2上转换发光为双光子荧光。很明显从基态4I_15/2到第一激发态的吸收很大,因为它的振子强度f和与1 520 nm激光的匹配都很好,随后的起源于第一激发态的能量传递和相继吸收都很易于发生,这导致了1 520 nm激光激发下的Er(0.5): FOG材料的丰富和有意义的上转换发光现象。