Zur Unterscheidung von lösungsmittelhaltigen pseudopolymorphen Kristallformen und polymorphen Modifikationen bei Steroidhormonen. II

Zusammenfassung Reichstein-S-acetat, Dexamethasonacetat,-Oestradiol, Methandriol, Dehydropregnenolon, Androsteron und Stanolon wurden auf ihre Fähigkeit zur Bildung lösungsmittelhaltiger Kristalle untersucht. Dabei zeigte sich, daß-Oestradiol mit allen 30 organischen Lösungsmitteln, die zur Anwendung gelangten, pseudopolymorphe Kristallformen bildet. Eine Begrenzung scheint nur durch die Zahl der verfügbaren Lösungsmittel gegeben. Methandriol verhält sich ähnlich wie-Oestradiol. Es wurden 16 Lösungsmittel ausgewählt und ebensoviele pseudopolymorphe Kristallformen erhalten. Auch von Dexamethasonacetat lassen sich zahlreiche lösungsmittelhaltige Formen herstellen. Reichstein-S-acetat und Dehydropregnenolon vermögen im allgemeinen nur Lösungsmittel mit Sauerstoffunktion im Kristall festzuhalten. Androsteron und Stanolon dagegen kristallisieren nicht mit organischen Lösungsmitteln, sie sind nur zur Hydratbildung befähigt. Zur Unterscheidung lösungsmittelhaltiger Kristallformen von polymorphen Modifikationen wurden die Thermomikroskopie und die IR-Spektroskopie herangezogen.

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Summary Reichstem-S-acetate, dexamethasone acetate,-oestradiol, methandriol, dehydropregneneolone, androsterone and stanolone were studied with respect to their ability to form crystals containing solvent. It was found that-oestradiol yields pseudopolymorphic crystal forms with all 30 solvents tried. A limitation seemingly is set only by the number of solvents available. Methandriol behaves similarly to-oestradiol. Sixteen solvents were selected and an equal number of pseudopolymorphic crystal forms obtained. Numerous forms containing solvent can be prepared likewise from dexamethasone acetate. Reichstem-S-acetate and dehydropregneneolone in general are capable of holding in the crystal only solvents that have oxygen function. Androsterone and stanolone in contrast do not crystallize with organic solvents, they are capable only of yielding hydrates. Thermomicroscopy and IR-spectroscopy were called on to distinguish between crystal forms, that carry solvents, and polymorphic modifications.

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Herrn Prof. Dr.H. Lieb zum 80. Geburtstag gewidmet.     

Study of satellite structure found in the photoelectron spectra of gaseous alkenes

The satellite structure in the photoelectron spectrum of the C(1s) shell has been studied for the following compounds: ethylene, propylene, 1-butene, trans-2-butene, cis-2-butene, butadiene and, for comparison, propane. The structure can be divided into two parts: a relatively sharp peak due to π → π* excitation and a broad complex band involving excitation of σ orbitals. Calculation of electron shakeup probabilities has been carried out using CNDO wave functions and compared with experiment. Reasonably good agreement was obtained, and the general problem of characterizing carbon—carbon double bond behavior by satellite structure due to electron shakeup is discussed.     

Si-SiO2膜的椭圆偏振光谱

我们建立了椭圆偏振光谱仪装置,提出一种较简便的测定方法(测I_max,I_min,θ_min,算(ψ,Δ)-λ),并对具有不同厚度氧化硅膜的硅样品进行了测量。还在理论上计算了光谱曲线,与实验结果基本相符。最后,对比了测定膜厚的偏振光谱法与消光法。 关键词：     

Determination of the lattice vibrations of imidazole by neutron scattering

The external molecular vibrations of deuterated imidazole have been investigated at 12 K for wave vectors along the three principal directions of the Brillouin zone by neutron scattering and by Raman scattering at the zone center. A complete symmetry assignment is obtained. The dominant role of the N-H … N hydrogen bond within the intermolecular interactions is reflected in a relatively simple manner in the shape of the dispersion curves because of the chain-like arrangement of hydrogen bonds. The experiment yields directly a stretching force constant of 0.33 mdyn Å^?1 for this bond. This value is compatible with monopole-dipole and dipole-dipole interactions as major contributions to the attractive interactions of the hydrogen bond of this length (2.86 Å). Relatively strong static monopoles and dipoles are confirmed by a $\text{CNDO}\text{2}$ calculation and are consequently incorporated into the interaction model.     

异种DNA对胚胎发育的影响

有平衡器之东方蝾螈的DNA和无平衡器之黑斑蛙DNA当分别注射至黑斑蛙的受精卵内时.两者都能使受注射卵发育成的有些蝌蚪在左鳃盖上具有类似平衡器的突出物.基于这些事实,可以推论蝌蚪的类似平衡器的突出物既不是由于遗传转化,也不是平衡器的诱导而是DNA对胚胎发育的非特异性效应.     

Precise determination of 6Li cold collision parameters by radio-frequency spectroscopy on weakly bound molecules

We employ radio-frequency spectroscopy on weakly bound (6)Li(2) molecules to precisely determine the molecular binding energies and the energy splittings between molecular states for different magnetic fields. These measurements allow us to extract the interaction parameters of ultracold (6)Li atoms based on a multichannel quantum scattering model. We determine the singlet and triplet scattering lengths to be a(s) = 45.167(8)a(0) and a(t) = -2140(18)a(0) (1a(0) = 0.052 917 7 nm), and the positions of the broad Feshbach resonances in the energetically lowest three s-wave scattering channels to be 83.41(15), 69.04(5), and 81.12(10) mT.     

Noncollinear magnetic order in quasicrystals

Based on Monte Carlo simulations, the stable magnetization configurations of an antiferromagnet on a quasiperiodic tiling are derived theoretically. The exchange coupling is assumed to decrease exponentially with the distance between magnetic moments. It is demonstrated that the superposition of geometric frustration with the quasiperiodic ordering leads to a three-dimensional noncollinear antiferromagnetic spin structure. The structure can be divided into several ordered interpenetrating magnetic supertilings of different energy and characteristic wave vector. The number and the symmetry of subtilings depend on the quasiperiodic ordering of atoms.     

Three-body recombination at large scattering lengths in an ultracold atomic gas

We study three-body recombination in an optically trapped ultracold gas of cesium atoms with precise magnetic control of the s-wave scattering length a. At large positive values of a, we measure the dependence of the rate coefficient on a and confirm the theoretically predicted scaling proportional to a(4). Evidence of recombination heating indicates the formation of very weakly bound molecules in the last bound energy level.     

A Note on Shelling

The radial distribution function is a characteristic geometric quantity of a point set in Euclidean space that reflects itself in the corresponding diffraction spectrum and related objects of physical interest. The underlying combinatorial and algebraic structure is well understood for crystals, but less so for non-periodic arrangements such as mathematical quasicrystals or model sets. In this note we summarise several aspects of central versus averaged shelling, illustrate the difference with explicit examples and discuss the obstacles that emerge with aperiodic order.