随机利率下跳-扩散过程的产量保险定价模型

本文研究了农产品价格为一般的跳-扩散模型,随机跳部分为复合Poisson过程,并假设远期利率服从HJM模型,利用测度变换技巧,给出了合同的在此模型下的解析解.     

Isotopes in groundwater as indicators of climate changes

Isotopes of the water molecule (δ¹⁸O and δ²H) are a well-used tool for investigating groundwater origin and history (i.e. tracing the recharge conditions over time, processes occurring during infiltration of rainwater towards aquifers and those involved in the water-rock interaction, and mixing of different waters).This review covers several large European aquifers (Portugal, France, UK, Switzerland, Germany, Hungary, and Poland), which were investigated in terms of their recharge conditions, and the story of the groundwater at a large scale, involving recent, Holocene and Pleistocene components and their eventual mixing.     

Selective synthesis of monoclinic and tetragonal phase LaVO<Subscript>4</Subscript> nanorods via oxides-hydrothermal route

Pure monoclinic (m-) and tetragonal (t-) LaVO₄ nanorods are successfully obtained via a facile oxides-hydrothermal method, in which V₂O₅ and La₂O₃ bulk powders are directly utilized as precursors without pretreatment. It is found that ethylenediamine tetraacetic disodium salt (EDTA) is a key factor for synthesizing t-LaVO₄. The as-obtained products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED). The FTIR spectra of VO₄ around 800 cm⁻¹ are suggested as an effective auxiliary means to identify the crystal phase of LaVO₄. UV–Visible spectra of LaVO₄ nanomaterials are obvious blue shift compared with the bulk m-LaVO₄ materials. The different photoluminescent properties of Eu³⁺ doped m- and t-LaVO₄ are demonstrated. A dissolution–precipitation mechanism is mainly responsible for the anisotropic morphology and phase control evolution of the LaVO₄ nanocrystals. The oxides-hydrothermal system is also applicable to prepare other pure LnVO₄ (Ln³⁺: Nd³⁺, Y³⁺, Sm³⁺) and doped LnVO₄ nanomaterials.     

Phase transition characteristics of Ge–Sb–Te pseudobinary alloys in laser irradiation measurement

Optical switching and structural transformation of GeTe–Sb₂Te₃ pseudobinary alloys, Ge₂Sb₂Te₅, Ge₁Sb₂Te₄, and Ge₁Sb₄Te₇, were studied for data storage application. As-deposited Ge₂Sb₂Te₅, Ge₁Sb₂Te₄, and Ge₁Sb₄Te₇ thin films were amorphous and they crystallized to FCC and HCP upon heat treatment. Crystallization was accelerated by increasing the proportion of Sb₂Te₃ rather than GeTe in Ge–Sb–Te compounds; this was observed by reflectivity changes under nanosecond laser irradiation in static tester. The different crystallization kinetics according to composition might be affected by the structural incompatibility of GeTe under the ‘Umbrella Flip’ theory.     

葡萄糖酸锌辅助治疗中心视网膜病变的临床观察

中心视网膜病变２１例，对照组１０例，治疗组在对照基础上加服葡萄糖酸锌片，对中心视网膜病变的总有效率治疗组达８５％，对照组为６０％，有显著差异。     

Synergistic extraction of lanthanoids(III) with 2-thenoyltrifluoroacetone and benzoic acid: thermodynamic parameters in the complexation in organic phases and the hydration

In order to examine the reason why the magnitude of the synergistic effect observed in the extraction of lanthanoids(III) with a β-diketone and a monodentate Lewis base generally decreases along with increasing atomic number, the hydration number of the extracted species when lanthanoids(III) are extracted with TTA (2-thenoyltrifluoroacetone, HA) and benzoic acid (HB) into chloroform by Karl Fischer titration and the enthalpy change in complexation between LnA₃ and HB by calorimetric titration were determined across the lanthanoid series at 25 °C.It has been concluded that since the decrement of entropy change caused by the change in the number of released water molecules and in the coordination number of lanthanoids(III) upon complexation is larger than the increment of the enthalpy change, the values of the second formation constants of the complexes decrease with increasing the atomic number across lanthanoid series so that the magnitude of the synergistic extraction decreases with increasing the atomic number.