Paul阱内的压缩效应与量子跃迁

处理一个一维Ｐａｕｌ阱系统中的压缩现象与量子跃迁现象，对于阱内的最强压缩态和共振跃迁（一种极不稳定状态）之间的关系作了阐述，并对利用压缩性质在阱内进行精密测量的可能性作了讨论     

量子计算与超冷离子

通过介绍量子计算的基本概念和特点，并对比目前人们使用的计算机的计算方式，对于如何利用囚禁在离子阱中的超冷离子进行量子计算作了简要的叙述．     

Smaller Output Beam Divergence in the Slowly Opened Q-Switch Operation

The mechanism of the slowly opened Q-switch operation was investigated thoroughly. Maximum energy extraction from the resonator could be optimized, and the smallest output beam divergence could be achieved. In this article, we present a detailed analysis that has numerically verified the mode-selection mechanism in the slowly opened Q-switch operation, and the degree of the smaller output laser beam divergence that has been achieved. The mechanism of the slowly opened Q-switch operation is the inherent advantage of the passive saturable absorber in this operation. We can use the maximum energy extraction and the smallest output beam divergence results of the slowly opened Q-switch operation to design and optimize various passive saturable absorbers: plastic dye sheets, LiF:F₂⁻ color center crystals, Cr4⁺: YAG crystals, RG1000 color glass filters, and the single crystal semiconductor saturable absorber wafers that are in developed in our microchip laser systems.     

Low Dimension Semiconducting Composite Nanomaterials

Recently, low dimension nanostructures have gained considerable attention due to their technological potential as unique types of nanoscale building blocks for future optoelectronic devices and systems. Semiconducting composite nanomaterials, which can combine the advantages of two or more components, have been the focus in the area of nanomaterials synthesis and device application.In this paper, we report our work on the preparation of composite nanomaterials based on CNTs.CNTs were coated by organic or inorganic species via novel and facile methods (Fig. 1 and Fig.2).These functional CNTs based composites show eminent prospects and opportunities for new applications in a wide variation of areas.     

Massenspektrometrische Beobachtungen und chemische Transportexperimente mit den Systemen VCl3/Al2Cl6 und VCl2/Al2Cl6

Mass Spectroscopic Observations and Chemical Transport Experiments with the Systems VCl₃/Al₂Cl₆ and VCl₂/Al₂Cl₆ By mass spectrometry the equilibrium VCl_3,s + 0.5 Al₂Cl_6,g ? VAlCl_6,g has been determined: ΔH°(298) = 25.6(±0.5) kcal; ΔS°(298) = 23.0(±3) cal/K, ΔCp (assumed) = ?4 cal/K. This is approximately in agreement with results determined by ligand field spectroscopy by ANUNDSKÅS and ØYE (A. and Ø.). For the dimerization of VCl_3,g values for ΔH and ΔS have been derived. The molecule VAl₂Cl₉ assumed by A. and Ø. could not been observed by mass spectrometry. For the VCl₂/Al₂Cl₆ complex, observed by chemical transport, A. and Ø. give the formula VAl₃Cl₁₁. This molecule could not been observed by mass spectrometry. This suggests a smaller concentration, compared with the results of A. and Ø. Stabilization of VCl_2,s (by metal-nietal-bonds) shifts the reaction to the left, whith explains the lower complex concentration as well as the larger molecular weight of the complex. With chlorides stabilized by stronger metal-metal bonds (MoCl₃, MoCl₂, Nb₃Cl₈) AlCl₃ complexes are not formed in observable concentrations. The chemical transport of VCl₂ with Al₂Cl₆ needs relatively high temperatures (973 → 873 K). In this case the addition of SiCl₄ hinders the attack of the quartz ampoule by Al₂Cl₆. Using a VCl₃ + VCl₂ mixture, VCl₃ is transported by Al₂Cl₆ (673 → 623 K) into the colder region. If afterwords the ampoule is reversed, VCl₃ again moves into the colder region, but the thermal decomposition of VCl₃ at the same time causes that a VCl₂-residue remains in the hot region.     

Gas-phase derivatization of [C3H5]+ ions using tandem mass spectrometry methods A13C labelling study

The study of specifically ¹³C-labelled precursors sheds further light on the gas-phase chemistry of allyl and 2-propenyl cations. It is demonstrated that both species are formed from allyl and 2-propenyl bromide upon 70 eV electron impact ionization without skeletal reorganization. Gas-phase derivatization of the [C₃ H₅]⁺ ions with benzene facilitates, as suggested and observed earlier, the distinction of the two isomers using collision-induced dissociation of the Wheland complexes (or isomers thereof). The ¹³C labelling data clearly demonstrate that 64% of allyl cations survive the derivatization while 36% isomerize to 2-phenylpropyl cations; the latter are also formed via the reaction of 2-propenyl cation with benzene, protonation of α-methylstyrene and water loss from protonated 2-phenyl-2-propanol, respectively. Unimolecular loss of C₂H₄ from protonated allylbenzene proceeds via two competing reaction channels: one involves heterolysis of 1-phenylpropyl cations (～30%); the major pathway (～70%), however, involves decomposition via propylene benzenium ions.     

酞菁氧钛/卟啉氧钒复合体系光导性能的协同增强效应

在酞菁氧钛（TiOPc)／卟啉氧钒（VOTPP）复合光生材料中发现了光敏性的非线性增强现象，对复合体系的电子跃迁光谱和X射线衍射图的研究结果表明，在基态下两种材料之间没有明显相互作用，光致放电研究说明，该现象来自光激发状态下复合体系中的隙间态跃迁对光导的贡献，XPS测试结果表明酞菁氧钛与卟啉氧钒分子之间存在着定向的部分电荷转移，光致激发状态下的电荷转移是协同增强效应的起因，这种协同增强效应为利用弱的电子给体与弱的受体复合体系设计新型光导材料与器件提供了新方法。     

Enantioselective iodolactonization catalyzed by chiral quaternary ammonium salts derived from cinchonidine

Chiral quaternary ammonium salts derived from cinchonidine have been applied to catalyze the stereoselective iodolactonizations of trans-5-aryl-4-pentenoic acids leading to a mixture of two regioselectively iodolactonized products with fair to excellent yield (37-98%) and moderate enantioselectivity (exo = 42.0% ee, endo = 31.0% ee) under mild conditions. This work is the first example of asymmetric iodolactonization reaction in the presence of less than a stoichiometric amount of chiral reagent.     

Ellipsometric study of surfactant adsorption at the aqueous solution/air interface

Summary Ellipsometry has been applied to study the adsorption of sodium dodecylsulfate (NaDS) at the air/solution interface of the surfactant in water and aqueous sodium chloride. Results are expressed by the ellipticitye and the anglea which the major axis of the ellipse forms with the plane of incidence of the light. The ellipticity is found to change its sign at low NaDS concentrations and to pass a maximum somewhat below the cmc. Below the maximum the increment in ellipticity Aee is a linear function of the surface excess concentration dodecylsulfate. The slope e/gd this linear relation is found to decrease when inert electrolyte (NaCl) is added. The azimuth anglea increases slightly with NaDS concentration near and above the cmc. The results are discussed in terms of the Drude theory.

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Zusammenfassung Die Adsorption von Natrium Dodecylsulfat (NaDS) an der Oberfläche wäßßriger Lösungen wurde mit Hilfe eines Ellipsometers untersucht. Die Meßergebnisse werden durch die Elliptizität e und den Winkel a zwischen der Hauptachse der Ellipse und der Einfallsebene des Lichtstrahls ausgedrü ckt. Die Elliptizität wechselt ihr Vorzeichen im Bereich geringer Konzentrationen von NaDS und läuft durch ein Maximum etwas unterhalb der cmc des Tensids. Unterhalb des Maximums wird eine lineare Beziehung zwischen dem Inkrement der Elliptizität e und der Oberflächen-Überschußkonzentration von Dodecylsulfat gefunden. Durch Zugabe eines inerten Elektrolyten (NaC1) wird die Steigung e/ stark verringert. Der Azimuth-Winkel a nimmt im Bereich der cmc des Tensids schwach zu. Die Ergebnisse werden im Rahmen der Drude-Theorie diskutiert.

     

Nucleotides. Part XLIV. Synthesis,characterization, and biological activity of monomeric and trimeric cordycepin-cholesterol conjugates and inhibition of HIV-1 replication

The antivirally active 3′-deoxyadenylyl-(2′–5′)-3′-deoxyadenylyl-(2′–5′)-3′-deoxyadenosine (cordycepin trimer core) was modified at the 2′- or 5′-terminus, by attachment of cholesterol via a carbonate bond (→ 15 ) or a succinate linker (→ 16 and 27 ) to improve cell permeability. The corresponding monomeric conjugates 4 , 7 , and 21 of cordycepin were prepared as model substances to study the applicability of the anticipated protecting groups – the monomethoxytrityl (MeOTr), the (tert-butyl)dimethylsilyl (tbds), and the β -eliminating 2-(4-nitrophenyl)ethyl (npe) and 2-(4-nitrophenyl)ethoxycarbonyl (npeoc) groups – for the final deblocking steps without harming the ester bonds of the conjugate trimers. The syntheses were performed in solution using phosphoramidite chemistry. The fully protected trimer conjugates 13 , 14 , and 26 as well as all intermediates were characterized by elemental analyses, UV and ¹H-NMR spectra. The deblocked conjugates 15 , 16 , and 27 were pure according to HPLC and showed the correct compositions by mass spectra. Comparative biological studies indicated that cordycepincholesterol conjugate trimers 16 and 27 were 333- and 1000-fold, respectively, more potent inhibitors of HIV-1-induced syncytia formation than cordycepin trimer core.