Optimal buying at the global minimum in a regime switching model

This paper addresses the problem of buying an asset at its expected globally minimal price, to that end, we model it as an optimal stopping problem with regime switching driven by a continuous-time Markov chain. We characterize the optimal stopping time by optimizing the value functions and writing them as solutions of a system of integral equations. Finally we develop a stochastic recursive algorithm for numerical implementation.     

Tetrahydroboratobis(triphenylphosphine)copper(I): a vibrational spectroscopic study

Application of infrared and Raman spectroscopy together with hydrogen—deuterium substitution has allowed identification of at least seven of the twelve fundamental vibrational frequencies expected for the double bridge CuBH₄ unit in tetrahydroboratobis(triphenylphosphine)copper(I). Limited assignments for the AgBH₄ unit in the analogous silver compound, based on infrared data for the hydride deuteride, are also presented.     

基于粗集和熵权-TOPSIS法的高新技术企业自主创新能力评价

科学评价高新技术企业自主创新能力,可加快推进高新技术企业成为自主创新主体.运用粗糙集属性约简区分矩阵算法对高新技术企业自主创新能力评价指标进行约简,通过熵权法客观确定指标权重,采用TOPSIS法进行综合评价.以某市高新技术企业为具体实例,得出按企业登记注册类型分的各类高新技术企业自主创新能力排序,证明了该评价方法的可行性和有效性.     

Ti-2Al-2.5Zr合金He离子辐照效应研究

 在Ti-2Al-2.5Zr合金中注入能量为75 keV的He离子,注入剂量分别为5×10¹⁶cm^-2,1×10¹⁷ cm^-2。通过显微硬度测量和剖面电子显微观察,研究了He离子对Ti-2Al-2.5Zr合金力学性能和显微组织的影响。结果表明:样品的显微硬度随He离子注量的增加而升高,在温度为350和550 ℃的Ar气中退火后硬度有所下降。剖面电子显微观察发现有位错环和He气泡生成,退火后He气泡有长大、缺陷有回复的趋势。辐照产生的位错环是辐照后硬度升高的直接原因,其退火发生回复又引起硬度随退火温度的升高而降低。     

Simultaneous extraction of level 2 and level 3 characteristics from latent fingerprints imaged with quantum dots for improved fingerprint analysisc

The numbers of level 2 and level 3 features that can be mapped by CdTe QDs are signifi cantly larger than those obtained by cyanoacrylate fuming (a standard technique being adopted at the forensic crime scene for examination of invisible fi ngerprints) and inkpad imaging.     

The effects of temperature and electrolyte at acidic and alkaline pH on the electron transfer reactions of cytochrome c at In2O3 electrodes

Spectroelectrochemical and electrochemical methods were used to investigate the characteristics of heterogeneous electron transfer between cytochrome c and indium oxide electrodes. A linear temperature dependence of the formal potential of cytochrome c was observed from 5 to 75 °C in acidic media. This behavior is attributed to a linear variation in the conformation of ferricytochrome c that results in an increase in solvent exposure of the solvent-exposed heme edge. A break in the linear temperature dependence of the formal potential occurred at 40 °C in alkaline media. This reflects a distinct conformational change that accompanies the onset of thermal denaturation of ferricytochrome c. The small change in reaction center entropy, ΔS°_rc, of ca. −54 J K⁻¹ mol⁻¹ in neutral and acidic media (5 to ⩾ 55 °C) and in alkaline media (below 40 °C) is consistent with a small shift to a more stable conformation of cytochrome c that occurs upon reduction.Adsorption of reactant and product was detected. The strength and type of adsorption were found to be temperature- and pH-dependent. The characteristics of electron transfer between cytochrome c and an electrode depend on bulk solvent properties and electrode surface characteristics.     

基于香豆素衍生物的新型绿色/红色磷光有机电致发光主体材料的设计、合成及性能表征

设计并合成了一种新型的香豆素衍生物,3,3-’(1,3-苯基)双(7-乙氧基-4-甲基香豆素)(mEMCB),并系统地对该香豆素衍生物进行了结构表征、光物理性能、热物理性能及电化学性能的研究.mEMCB具有较高的三重态能级(2.42eV),可敏化绿色、红色磷光掺杂材料.同时,mEMCB还具有较好的热稳定性(T_g:79.72℃,T_d:361.49℃),其T_g明显高于目前广泛使用的磷光主体材料CBP.研究结果表明,mEMCB是一个潜在的可以用于绿色和红色磷光有机电致发光器件的主体材料.     

双极绿色磷光主体材料1-甲基-3-[4-(9-咔唑基)苯基]-4-苯基喹啉-2(1H)-酮的合成与性能研究

设计并合成了一种基于喹诺酮衍生物的双极绿色磷光主体材料1-甲基-3-[4-(9-咔唑基)苯基]-4-苯基喹啉-2(1 H)-酮.计算发现,化合物的HOMO轨道的电子云位于咔唑基团,LUMO轨道的电子云位于喹诺酮基团,是一种良好的双极材料.化合物的磷光发射峰为515 nm(2.41 eV),符合绿色磷光主体材料的基本要求(>2.4 eV).热失重和差热分析结果表明,该化合物具有较高的热稳定性,分解温度和玻璃化转变温度分别为312℃和105℃.研究结果表明:该新型化合物是一种潜在的具有双极特性的绿色磷光主体材料.     

Ni-based photocatalytic H2-production cocatalysts2

Photocatalysis is believed to be one of the best methods to realize sustainable H₂ production. However, achieving this through heterogeneous photocatalysis still remains a great challenge owing to the absence of active sites, sluggish surface reaction kinetics, insufficient charge separation, and a high thermodynamic barrier. Therefore, cocatalysts are necessary and of great significance in boosting photocatalytic H₂ generation. This review will focus on the promising and appealing low-cost Ni-based H₂-generation cocatalysts as the alternatives for the high-cost and low-abundance noble metal cocatalysts. Special emphasis has been placed on the design principle, modification strategies for further enhancing the activity and stability of Ni-based cocatalysts, and identification of the exact active sites and surface reaction mechanisms. Particularly, four types of modification strategies based on increased light harvesting, enhanced charge separation, strengthened interface interaction, and improved electrocatalytic activity have been thoroughly discussed and compared in detail. This review may open a new avenue for designing highly active and durable Ni-based cocatalysts for photocatalytic H₂ generation.