Ferron逐时比色法中显色剂Ferron浓度对Al-Ferron体系反应动力学的影响

Ferron逐时比色法中Al-Ferron体系反应动力学常被视为准一级反应,由此可推得相应的拟合方程并测得相应的反应速率常数kb,显色剂Ferron作为反应物之一其用量必然直接影响测量的结果。以不同OH/Al比的聚合氯化铝溶液为研究对象,抓住Ferron浓度这一核心要素,对Al-Ferron体系反应动力学过程进行了系统研究。结果表明,[Ferron]≥2.0×10^(-3)mol/L是确保动力学速率常数kb准确测量的基本保证。     

Ce掺杂Mn3O4及其电化学电容行为

用溶胶-凝胶方法合成了Mn₃O₄和Ce掺杂Mn₃O₄. 采用X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对其结构和形貌进行了表征. 采用循环伏安、电化学交流阻抗和恒流充放电技术对其电化学性能进行了测试. 研究结果表明, Ce掺杂对Mn₃O₄的形貌和电化学性能均有显著影响. 当Ce离子占金属离子总量的3%时, 掺杂Mn₃O₄的单电极比电容高达477 F·g^-1, 比未掺杂的提高了43.7%, 并且表现出更好的循环稳定性.     

A Phase-Controlled Optical Parametric Amplifier Pumped by Two Phase-Distorted Laser Beams

We theoretically study the phase characteristic of optical parametric amplification （OPA） or chirped pulse OPA （OPCPA） pumped by two phase-distorted laser beams. In the two-beam-pumped optical parametric amplification （TBOPA）, due to spatial walk-off, both of the pump phase distortions will be partly transferred to signal in a single crystal so as to degrade the signal beam-quality, which will be more serious in high-energy OPCPA. An OPA configuration with a walkoff-compensated crystal pair is demonstrated for reducing the signal phase distortion experienced in the first stage and ensuring the signal phase independent of two pump phase distortions through the second crystal, hence maintaining the signal beam-quality. Such a TBOPA is similar to the conventional quantum laser amplifier by means of eliminating its sensitivity to the phase and number of the pump beams.     

ON THE FALSE DEGENERACY OF THE HELMHOLTZ BOUNDARY INTEGRAL EQUATIONS

In this paper, the false degeneracy of the Helmholtz boundary integral equations is examined. A new theory to explain the false degeneracy of the Helmholtz boundary integral equations is given. In this proposed theory, a false degeneracy of the boundary integral equation is explained as finding a non-trivial source distribution such that it results in trivial field quantities inside the domain interested and non-trivial field quantities for its counter part, i.e., outside the domain interested. It is clearly explained that such a false degeneracy is independent of prescribed boundary conditions but dependent on the integral equation one selects. Moreover, the false degeneracy of the integral equation for the interested domain relates to the eigenproblem for its counter part. Under such a unified theory, the fictitious eigenvalue, spurious eigenvalue and pseudo-fictitious eigenvalue can be explained in a simple mathematical frame. It is concluded from our theoretical analysis that a multiply connected domain results in the pseudo-fictitious eigenvalue even the complex-valued formulations are used. In order to eliminate various kinds of false degeneracy, two methods are employed according to the previous research. A unified view of these two methods is provided such that they can be thought to be equivalent from mathematical point of view. Several numerical examples are given to show the validity of current approach.     

零阶贝塞尔函数组成的两个正交系

给出了在常见的函数内积下任意两个零阶贝塞尔函数的内积公式，进而证明了由第一类和第二类零阶贝塞尔函数的线性函数族的正交性以及长度的表达式．     

杜仲茎部剥皮后塑料薄膜包裹的效应

本文观察并比较了杜仲茎部剥皮后,完全暴露的与立即包以透明和黑色塑料薄膜的,再生树皮的组织分化过程。结果在暴露的和包以透明塑料薄膜的树干上,新的维管形成层都在较深层的未成熟木质部中发生,而包黑塑料薄膜的,则在愈伤组织与木质部交界处的未成熟木质部或愈伤组织中发生。这种新形成层的早期分化很象原形成层,向内分化出螺纹管胞和导管,向外形成筛胞状分子。     

超声波在乙酸乙酯和乙酸甲酯中的弛豫吸收

关于超声波在乙酸乙酯和乙酸甲酯中的吸收问题曾引起了多次热烈的争论,为此,作者采用了行波中的光衍射法做了进一步的实验研究。在实验过程中,特别注意了仪器的精确度问题,并且对许多种吸收系数已知的标准液体进行了多次重复的测量,结果很好地符合于一般的公认值,且误差不超出5％。对于两种乙酸酯,测量的频率范围是3-30Mc,温度保持20℃。测量结果表明,在实验的误差范围内,吸收的实验值很好地落在唯象单弛豫理论所预期的曲线上,弛豫频率对乙酸乙酯约在12Mc附近,对乙酸甲酯约在7Mc附近。并且通过对不同纯度的乙酸乙酯进行重复的测量,表示杂质引起的附加吸收并不影响吸收曲线的特性。因此也就明某些作者测量得到两个弛豫频率的结果是不真实的。作者并认为Karpovich首先提出的旋转异构的理论是适合于解释这两种液体的驰豫吸收的机理的。     

紧致空间中辐射场的统计性质

通过对有限紧致空间中辐射场的研究来讨论腔中的原子-辐射场耦合系统. 利用T(1)×SO(4)群的表示, 给出了辐射场的单粒子波函数以及相应的色散关系. 由此详细讨论了紧致空间中辐射场的玻色-爱因斯坦统计. 发现其性质与空间的几何性质(曲率半径)有显著的依赖关系, 并表现与通常黑体辐射系统的显著差异.     

An Experimental Study of Mg Aggregation in AA5754 Alloys by Positron Annihilation Spectroscopy

Defects in an AA5754 （Al-3.0%Mg） alloy are investigated by coincidence Doppler broadening spectroscopy and positron lifetime spectroscopy. The results indicate enhancement of positron trapping by Mg atoms in this Al-Mg alloy after quenching treatment at 623K, which may be due to the formation of vacancy-Mg complexes or the aggregation of Mg near the vacancy sites. It is speculated that the aggregation of Mg atoms in the moderate temperature range is responsible for cracking in spot welding of AA5754 alloys.