TQ171.7//O482.31 2003021442Er<sup>3+</sup>:Yb<sup>3+</sup>共掺杂氟氧混合物玻璃的上转换发光研究=Study of up-conversion fluorescence in Er<sup>3+</sup>:Yb<sup>3+</sup>co-d...TQ171.7//O482.31 2003021442Er<sup>3+</sup>:Yb<sup>3+</sup>共掺杂氟氧混合物玻璃的上转换发光研究=Study of up-conversion fluorescence in Er<sup>3+</sup>:Yb<sup>3+</sup>co-dopedoxyfluoride glass[刊,中]/阳效良（湘潭大学物理系.湖南,湘潭（411105））,刘正威…//光谱学与光谱分析.—2002,22（3）.—357-359制备了化学西文为（50-x）GeO<sub>2</sub>·PbF<sub>2</sub>·WO<sub>3</sub>·（6+x）CdF<sub>2</sub>·1.4Yb<sub>2</sub>O<sub>3</sub>·0.6Er<sub>2</sub>O<sub>3</sub>（x=10,20,30）氟氧混合物玻璃。研究了930nm发光二极管激发下Er<sup>3+</sup>:Yb<sup>3+</sup>共掺杂情形下的Er<sup>3+</sup>离子的上转换发光特性,观测到了Er<sup>3+</sup>离子中心波长位于543、550和655nm处的三个强荧光发射带。通过对样品的反斯托克斯喇曼光谱的测量,确定了基质的最大声子能量,在此基础上分析了上转换荧光的产生机制。利用基质的平均电负性差和平均阳离子场强这两个参数,讨论了基质材料中GeO<sub>2</sub>和CdF<sub>2</sub>展开更多
This work is aimed at studying the strengthening of reinforced concrete (R. C.) beams using prestressed glass fi- ber-reinforced polymer (PGFRP). Carbon fiber-reinforced polymer (CFRP) has recently become popular for ...This work is aimed at studying the strengthening of reinforced concrete (R. C.) beams using prestressed glass fi- ber-reinforced polymer (PGFRP). Carbon fiber-reinforced polymer (CFRP) has recently become popular for use as repair or rehabilitation material for deteriorated R. C. structures, but because CFRP material is very stiff, the difference in CFRP sheet and concrete material properties is not favorable for transferring the prestress from CFRP sheets to R. C. members. Glass fi- ber-reinforced polymer (GFRP) sheets with Modulus of Elasticity quite close to that of concrete was chosen in this study. The load-carrying capacities (ultimate loads) and the deflections of strengthened R. C. beams using GFRP and PGFRP sheets were tested and compared. T- and ⊥-shaped beams were used as the under-strengthened and over-strengthened beams. The GFRP sheets were prestressed to one-half their tensile capacities before being bonded to the T- and ⊥-shaped R. C. beams. The prestressed tension in the PGFRP sheets caused cambers in the R. C. beams without cracks on the tensile faces. The PGFRP sheets also enhanced the load-carrying capacity. The test results indicated that T-shaped beams with GFRP sheets increased in load-carrying capacity by 55% while the same beams with PGFRP sheets could increase load-carrying capacity by 100%. The ⊥-shaped beams with GFRP sheets could increase load-carrying capacity by 97% while the same beams with PGFRP sheets could increase the loading-carrying capacity by 117%. Under the same external loads, beams with GFRP sheets underwent larger deflections than beams with PGFRP sheets. While GFRP sheets strengthen R. C. beams, PGFRP sheets decrease the beams’ ductility, especially for the over-strengthened beams (⊥-shaped beams).展开更多
In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original...In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original values. According to the classical theory, the Tg of plastic component shall remain unchanged or move toward the lower Tg of rubber component in a rubber/plastic blend. However, ultra-fine full-vulcanized powdered rubber (UFPR) with a diameter of ca. 100 nm can simultaneously increase the toughness and the Tg of plastics, which is abnormal and is difficult to explain by classical theory. In this feature article, the abnormal behavior and its mechanism are discussed in detail.展开更多
文摘TQ171.7//O482.31 2003021442Er<sup>3+</sup>:Yb<sup>3+</sup>共掺杂氟氧混合物玻璃的上转换发光研究=Study of up-conversion fluorescence in Er<sup>3+</sup>:Yb<sup>3+</sup>co-dopedoxyfluoride glass[刊,中]/阳效良（湘潭大学物理系.湖南,湘潭（411105））,刘正威…//光谱学与光谱分析.—2002,22（3）.—357-359制备了化学西文为（50-x）GeO<sub>2</sub>·PbF<sub>2</sub>·WO<sub>3</sub>·（6+x）CdF<sub>2</sub>·1.4Yb<sub>2</sub>O<sub>3</sub>·0.6Er<sub>2</sub>O<sub>3</sub>（x=10,20,30）氟氧混合物玻璃。研究了930nm发光二极管激发下Er<sup>3+</sup>:Yb<sup>3+</sup>共掺杂情形下的Er<sup>3+</sup>离子的上转换发光特性,观测到了Er<sup>3+</sup>离子中心波长位于543、550和655nm处的三个强荧光发射带。通过对样品的反斯托克斯喇曼光谱的测量,确定了基质的最大声子能量,在此基础上分析了上转换荧光的产生机制。利用基质的平均电负性差和平均阳离子场强这两个参数,讨论了基质材料中GeO<sub>2</sub>和CdF<sub>2</sub>
文摘This work is aimed at studying the strengthening of reinforced concrete (R. C.) beams using prestressed glass fi- ber-reinforced polymer (PGFRP). Carbon fiber-reinforced polymer (CFRP) has recently become popular for use as repair or rehabilitation material for deteriorated R. C. structures, but because CFRP material is very stiff, the difference in CFRP sheet and concrete material properties is not favorable for transferring the prestress from CFRP sheets to R. C. members. Glass fi- ber-reinforced polymer (GFRP) sheets with Modulus of Elasticity quite close to that of concrete was chosen in this study. The load-carrying capacities (ultimate loads) and the deflections of strengthened R. C. beams using GFRP and PGFRP sheets were tested and compared. T- and ⊥-shaped beams were used as the under-strengthened and over-strengthened beams. The GFRP sheets were prestressed to one-half their tensile capacities before being bonded to the T- and ⊥-shaped R. C. beams. The prestressed tension in the PGFRP sheets caused cambers in the R. C. beams without cracks on the tensile faces. The PGFRP sheets also enhanced the load-carrying capacity. The test results indicated that T-shaped beams with GFRP sheets increased in load-carrying capacity by 55% while the same beams with PGFRP sheets could increase load-carrying capacity by 100%. The ⊥-shaped beams with GFRP sheets could increase load-carrying capacity by 97% while the same beams with PGFRP sheets could increase the loading-carrying capacity by 117%. Under the same external loads, beams with GFRP sheets underwent larger deflections than beams with PGFRP sheets. While GFRP sheets strengthen R. C. beams, PGFRP sheets decrease the beams’ ductility, especially for the over-strengthened beams (⊥-shaped beams).
文摘In terms of the classical theory in textbooks, the two components with phase separation in a binary polymer blend will, depending on their compatibility, have their respective Tg get closer or remain in their original values. According to the classical theory, the Tg of plastic component shall remain unchanged or move toward the lower Tg of rubber component in a rubber/plastic blend. However, ultra-fine full-vulcanized powdered rubber (UFPR) with a diameter of ca. 100 nm can simultaneously increase the toughness and the Tg of plastics, which is abnormal and is difficult to explain by classical theory. In this feature article, the abnormal behavior and its mechanism are discussed in detail.
