Behavior of iodododecane in nuclear fuel reprocessing

By simulation experiments with a 10^–5 mol/l solution of iodododecane labeled with¹³¹I in n-dodecane the influence of various materials and conditions, which are possible in nuclear fuel reprocessing, has been investigated. The formation of decomposition products was detected via HPLC with a radioactivity monitor. By means of²⁵²Cf plasma-desorption mass spectrometry (PDMS) the decomposition products were identified. It was found that a temperature of 100°C favored the formation of iodoalkanes with chain lengths of C₁ to C₁₁. The presence of TBP(tri-n-butyl-phosphate) accelerated the decomposition of iodododecane. In pure TBP only iodobutane was formed as a decomposition product.     

Chemical isolation of element 106 from aqueous solutions according to model experiments with short-lived tungsten isotopes

The short-lived isotopes of W and their descendants have been isolated from the products of the bombardment of¹⁴⁴Sm with²⁴Mg by a fast continuous ion-exchange method, using HF solution media. The feasibility of this method for isolation of element 106 is discussed.     

The nitrogen pentoxide dissociation equilibrium

The third-law method is used to assess the authenticity of available equilibrium constants for the thermal dissociation of N₂O₅ ? NO₂ + NO₃. © 1994 John Wiley & Sons, Inc.     

Temperature-dependent behavior of birefringence and rotation of the optical indicatrix in crystals of deuterated triglycinesulfate

On the basis of a complex null-polarimetric method, the natural birefringence and the rotation of the optical indicatrix in crystals of deuterated triglycinesulfate are measured in the temperature range of 300–340 K. The temperature-dependent behavior of the optical parameters is shown to be close to that observed previously in triglycinesulfate crystals. Changes in them upon the ferroelectric phase transition can be accounted for by the spontaneous quadratic electro-optic effect, with the values of the electro-optic coefficients being larger by a factor of 1.4 than in triglycinesulfate crystals.     

Asymptotic behaviors of competitive Lotka-Volterra system with stage structure

In this paper, a two-species competitive model with stage structure is presented and studied. Results on the global extinction and permanence are given, which generalize the well-known three theorems for the two species competitive system and, moreover, they confirm the negative effect of stage structure on the permanence of populations as well as estimate the degree of such effect. Conclusions in this paper suggest that for a competitive community stage structure is also one of the important reasons that cause permanence and extinction.     

一类随机环境中的随机游动

在Solomn的模型的基础上对一类随机环境中随机游动进行了讨论，并得出了一个常返性准则和一些极限性质。     

甲基红染料掺杂的聚乙烯醇薄膜光存储特性的实验研究

用2倍频小型YAG激光(532nm)作为写入光和擦除光,用He-Ne激光器623.8nm线作为读出光,用CCD作为探测器,研究了不同写入光功率下,甲基红/聚乙烯醇(MR/PVA)薄膜光栅生长的动力学过程和不同擦除光功率下,光栅擦除的动力学过程.结合光栅生长曲线的波动现象,对光存储机制进行了新的探讨.实验发现,两写入光和读出光的功率配比为1:1:1时,可获得最大衍射效率,提出读出光对写入过程具有双重作用的物理模型,对此实验结果给出了合理的解释.     

A simple yet accurate boundary element method for continuum dielectric calculations

A simple yet accurate method for calculating electrostatic potentials using the boundary element continuum dielectric method is presented. It is shown that the limiting factor in accuracy is not the evaluation of integrals involving the interaction between boundary elements but rather a proper estimation of the self-polarization of a patch upon itself. We derive a sum rule that allows us to calculate this important self-polarization term in a self-consistent and simple way. Intricate integration schemes used in previous treatments are consequently rendered unnecessary while concurrently achieving at least comparable accuracy over earlier methods. In some model systems for which analytic solutions are available, the computed surface polarization charge and reaction field energy are correct to better than six significant figures. An application of the method to the calculation of hydration free energies is presented. Good agreement with experimental values is obtained.