温度对Nafion-结晶紫光纤湿度传感器性能的影响

The optical fiber relative humidity sensor based on Nation-crystal violet film was developed.The effect of samplef s temperature in the range from 299.15K to 324.15K on the sensing performance of the sensor was investigated. The mathematical function between temperature and the sensitivity of the sensor was established according to the reactive theory of sensor to the relative humidity, which was validated with the experiment. With the research, the application range of the sensor was extended, which made the sensor keep a good veracity when it was used in situ.     

Ultrasonic Study on Jahn-Teller Distortions in La1=3Sr2=3CoO3

系统研究了La1=3Sr2=3CoO3单相多晶样品在低温下的电磁输运性质和超声特性．电阻率测量表明,La1=3Sr2=3CoO3在整个温区内都表现出金属特性,并且在235 K处电阻率-温度曲线的斜率发生了变化,同时伴随着铁磁相变．超声声速在铁磁相变温度以下出现软化,并在120 K附近达到最小,之后,随着温度的进一步降低,声速开始硬化,同时出现了一个宽大的超声衰减峰．分析认为,该超声异常可能起源于中等自旋态Co3+的Jahn-Teller效应．     

Application of ultrasound as pretreatment for extraction of podophyllotoxin from rhizomes of Podophyllum peltatum

The effect of high-power ultrasound pretreatment on the extraction of podophyllotoxin from Podophyllum peltatum was investigated. Direct sonication by an ultrasound probe horn was applied at 24 kHz and a number of factors were investigated: particle size (0.18-0.6 mm), type of solvent (0-100% aqueous ethanol), ultrasonic treatment time (2-40 min), and power of ultrasound (0-100% power intensity, maximum power: 78 W). The optimal condition of ultrasound was achieved with 0.425-0.6 mm particle size, 10 min sonication time, 35 W ultrasound power, and water as the medium. There was no obvious degradation of podophyllotoxin with ultrasound under the applied conditions, and an improvement in extractability was observed. The SEM microscopic structure change of treated samples disclosed the effect of ultrasound on the tissue cells. The increased pore volume and surface area after ultrasonic treatment also confirmed the positive effect of ultrasound pretreatment on the extraction yield of podophyllotoxin from the plant cells.     

Calibration of Stress-triaxiality Dependent Crack Formation Criteria: A New Hybrid Experimental–Numerical Method

A new experimental technique has been developed to investigate the onset of fracture in metals at low and intermediate stress triaxialities. The gage section of a flat specimen has been designed such that cracks are most likely to initiate within the specimen center, remote from the specimen boundaries. Along with the specimen, a biaxial testing device has been built to apply a well-defined displacement field to the specimen shoulders. The stress state within the specimen is adjusted by changing the biaxial loading angle. Using this new experimental technique, the crack initiation in metals can be studied experimentally for stress triaxialities ranging from 0.0 to 0.6. The stress and strain fields within the specimen gage section are determined from finite element analysis. The reliability of the computational model of the test set-up has been verified by comparing the simulation results with laser speckle-interferometric displacement measurements during testing. Sample experiments have been performed on the Al-7Si-Mg gravity die casting alloy. A three-step hybrid experimental–numerical calibration procedure has been proposed and applied to determine a phenomenological crack formation criterion for the Al-7Si-Mg alloy.

THE EFFECT AND FUNCTION OF AliBu_2OR'''' ON BUTADIENE-PROPYLENE ALTERNATING COPOLYMERIZATION CATALYZED BY VO(OR)_2Cl-AIiBu_3 SYSTEM

Four kinds of AliBu_2OB' with different R' were synthesized. The effect of AliBu_2OR'/AliBu_3 mole ratio on the conversion, the [η] of copolymer and catalytic efficiency were studied. The conversion was increased obviously and the catalytic efficiency was 2.7 times higher than before. The effect of the amount of AliBu_2OR' on the valence state of vanadium ion and the change of the valence state of vanadium ion with reaction temperature and time were studied. The VIS and IR spectra of the trinary-component catalyst system were measured. The model of active center including AliBu_2OR' was proposed. The function of AliBu_2OB was explained.     

一类稀疏效应下具功能反应的捕食系统的定性分析

对稀疏效应下具有Holling Ⅲ类功能反应的一类捕食系统进行了定性分析,讨论了正平衡点的存在性和稳定性,并通过分析参数的取值范围得到了极限环、分界线环的存在条件与相关稳定性的结论.     

Energy Spectrum and Its Pressure-Induced Shift and g Factor of ZnS:Mn2+

By using strong-field scheme, the complete d⁵ energy matrix with D_2d symmetry has been constructed. Then, by diagonalization of this matrix at normal and various pressures,the whole energy spectrum [including the ground-state zero-field-splitting (GSZFS)], its PS and the g factor of the ground state for zns:Mn²⁺ have uniformly been calculated. According to the eigenfunctions and PS, the new assignments of five absorption bands have been given.The variation of tetragonal field with pressure makes a main contribution to the pressureinduced shift (PS) of GSZFS of zns:Mn²⁺, which supports the existence of tetragonal Jahn-Teller distortion in zns:Mn²⁺. It is found that when P≥62 kbar, t₂⁴(³T₁)e⁴T₁ merges with t₂e^{4 2}T₂, which has to be taken into account in the calculation of PS of the fifth band in the range of 1 bar ~ 95 kbar. It is demonstrated that the Mn²⁺ ions in ZnS:Mn²⁺ have tetrahedral coordination, and the difference between ζ and ζ' caused by the covalency effect is very important for GSZFS. The physical essentials of typical levels, GSZFS and their PS have been revealed. By taking into account the influence of covalency on t₂³(⁴A₂)e²(³A₂)⁴A₁ and t₂³(²E)e²(³A₂)⁴E, the positon of the third absorption band at normal pressure has been estimated.     

利用快分子离子与固体的相互作用对H2+,HD+和D+2结构的研究

利用快分子离子与固体的相互作用,依靠一套高分辨装置,测量了H2+,HD+和D2+的结构,得到其核间距分别为1.19±0.003 nm、1.25±0.003 nm和1.32±0.003 nm.通过对比,证实了分子离子结构中同位素效应的存在,分析了实验值和理论值存在差别的原因,讨论了实验结果中同位素效应产生的缘由.     

T1u×hg Jahn-Teller系统：D3d势阱中的频率分解与能级分裂

在C60分子中，未被填充的最低电子态具有T1u对称性，因此，对中性的C60而言，不论是通过分子内部激发，或是外部掺杂，都易被一个电子占据而形成Jahn-Teller（JT）活跃电子态.此态与五重简并的hg声子态耦合，构成所谓的T1u-hg -JT系统.在这一JT系统中，当只考虑电声的线性耦合时，其绝热势能面是一个槽形.但在实际的系统中，二阶电声耦合是存在的，理论研究表明，原来的势槽将被这二阶非线性耦合弯曲成D3d或D5d对称性的势阱.声子振动态在阱中将显示各向异性效应，使得声子沿不同的方向有不同的振动频率，进而影响势阱中的能级分布、势阱间的重叠积分，以及整个系统的隧道能级分裂等.对D3d势阱中各向异性效应进行了研究，利用幺正平移、?pik Pryce和标度变换等方法计算了系统势阱中的能级，以及阱中的振动频率，研究了势阱中的能级间隔以及微绕修正能量的变化，并由此导出了这些物理量在仅有线性耦合的势槽中变化的情形. 关键词： C60 Jahn-Teller效应 各向异性 电声耦合     

Many-body effects in hyperfine interactions in <Superscript>205</Superscript>Pb<Superscript>+</Superscript>

Ab initio calculations have been carried out to study the magnetic dipole and electric quadrupole hyperfine structure constants of ²⁰⁵Pb⁺. Many-body effects have been considered to all orders using the relativistic coupled-cluster theory in the singles, doubles and partial triples approximation. The trends of these effects are found to be different from atomic systems that have been studied earlier.