Zum Nachweis der Zuckercouleur im Bier

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Untersuchung von Honig

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2000 Vol.11 No.8 P.Preparation of AChE Inhibitors From Jujubogenin

A dammarane derivative dihydrojujubogenin-2-en-1-one, which possesses a skeleton and pharmacophore partially similar to those of Territrem B, a potent AChE inhibitor, was synthesized via three different paths. The anti-AChE activity of this compound and related analogue was measured.     

Bestimmung kleiner Mengen Zink in organischen Substanzen, insbesondere in Aepfelschnitten

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噻吩基和呋喃基四硫富瓦烯的合成及电化学性质

提供了一种合成噻吩基和呋喃基四硫富有瓦烯（ＴＴＦ）的方法，并用其合成了３种未见文献报道的噻吩基ＴＴＦ（Ⅶａ，Ⅷｂ，Ⅶｃ）和２种呋喃基ＴＴＦ（Ⅶｄ１，Ⅶｄ２）研究这些化合物的循环伏安行为及有关电化学性质，制得了一种Ⅶｂ与ＴＣＮＱ反应生成的电荷转移络合物，讨论了噻吩基ＴＴＦ和呋喃基ＴＴＦ在产物构型和电化学性质方面的差别。     

湖北十堰绿松石中杂质矿物自然硒的谱学研究

近期在湖北绿松石市场上出现一种带有肉眼可见的灰黑色异形杂质的绿松石,于此种绿松石的研究甚少。故选取来自湖北省十堰的一块该种绿松石原石,蓝色绿松石基底上布满形态各异、大小不一的灰黑色杂质,放大观察可见灰黑色杂质矿物呈金属光泽。对灰黑色杂质采用激光剥蚀电感耦合等离子体质谱仪进行原位微区微量元素测试、背散射电子图像物相观察、主量化学成分测试采用能谱仪进行半定量测试和电子探针定量测试以及显微激光拉曼光谱仪测试。灰黑色杂质矿物的LA-ICP-MS测试激光剥蚀束斑直径及深度的影响,测试结果表现为灰黑色杂质矿物和少量绿松石的混合物的化学成分含量,灰黑色杂质矿物处Se含量为95 927～221 394 μg·g-1明显高于蓝色基底绿松石中Se的含量（146～212 μg·g-1）,灰黑色杂质处的测试结果中CuO含量为7.47%～9.28%、Al₂O₃含量为28.1%～35.7%,P₂O₅含量为30.1%～37.8%为少量绿松石混杂产生;背散射电子图像表明杂质矿物结晶颗粒细小,细小的杂质矿物与绿松石混杂在一起,他形的杂质矿物为多个晶体集合在一起形成的集合体,能谱测试结果表明杂质矿物主要含有Al,P,Fe,Cu和Se,电子探针主量化学成分定量测试结果表明杂质矿物主要含有Se,含量为79.34%～87.97%,此外,由于杂质矿物结晶颗粒细小,杂质矿物集合体中可见杂质矿物与绿松石混杂,因此化学成分定量测试结果中还呈现有绿松石中的Al,P,Fe,Cu和Al含量约为0.93%～4.13%,Cu含量约为1.30%～2.04%,P含量约为0.66%～2.40%,Fe含量约为0.31%;杂质矿物的显微激光拉曼光谱峰为位于144和235 cm-1处的尖锐拉曼谱峰,结合化学成分谱学测试结果可鉴别该杂质矿物主要为自然硒。硒矿物是绿松石中新发现的杂质矿物,绿松石中杂质矿物自然硒的发现可以为珠宝从业者鉴别绿松石提供有效的鉴定依据。     

Mulliken-Hush analysis of a bis(triarylamine) mixed-valence system with a N...N distance of 28.7 A

An organic mixed valence compound with a spacer length of 25 unsaturated bonds separating two amine redox centres was synthesised and the electron transfer behaviour was investigated in the context of a Mulliken-Hush analysis in order to estimate the longest redox centre separation for which an intervalence charge transfer band can be observed.     

2.2]paracyclophane-bridged mixed-valence compounds: application of a generalized Mulliken-Hush three-level model

A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.     

Rabi oscillations and excitation trapping in the coherent excitation of a mesoscopic frozen Rydberg gas

We demonstrate the coherent excitation of a mesoscopic ensemble of about 100 ultracold atoms to Rydberg states by driving Rabi oscillations from the atomic ground state. We employ a dedicated beam shaping and optical pumping scheme to compensate for the small transition matrix element. We study the excitation in a weakly interacting regime and in the regime of strong interactions. When increasing the interaction strength by pair state resonances, we observe an increased excitation rate through coupling to high angular momentum states. This effect is in contrast to the proposed and previously observed interaction-induced suppression of excitation, the so-called dipole blockade.