Case Study: Doping Substances in Equestrian Food Supplements

In the course of investigations on equestrian supplemental products for the presence of doping substances, two products were found to contain forbidden substances. As reported earlier a plant extract (Mexican cactus extract) named “Energy 5” contained the anabolic androgenic steroids (AAS) stanozolol, 17β-hydroxy-17α-methyl-5α-androstane-3β-ol (3β,5α-THMT) as well as mestanolone not declared on the label. In the present study, a product called “Super Kalm Paste” was tested. Analysis by gas chromatography - mass spectrometry (GC-MS) revealed that the preparation contained the class I anti-arrhythmics quinine (trade names Kinidin^TM, Durules) and cinchonine. The samples were prepared according to a sample preparation procedure established for anabolic steroids in nutritional supplements for humans. The sample treatment comprised the extraction and purification of the analytes as well as the chemical conversion with N-methyl-N-trimethylsilyl-trifluoracetamide (MSTFA) to yield the trimethylsilyl (TMS)-derivatives. To verify whether the administration of such products could lead to positive doping tests, a pilot excretion study on “Energy 5” was conducted with two geldings, and urine samples were collected. Gas chromatography - high resolution mass spectrometry (GC-HRMS) after solid phase extraction and mixed derivatisation has demonstrated the presence of the stanozolol metabolite 16β-hydroxy-stanozolol in urine samples after “Energy 5” application.     

PHOTOCHEMISTRY and PHOTOBIOLOGY WITHOUT LIGHT

Abstract— This review covers the literature since 1980 on chemically and enzymatically generated electronically excited species. The emphasis lies on triplet states of carbonyl products that are derived from dioxetanes and dioxetanones as precursors or from suitable enzymatic oxygenations. Singlet oxygen, an important excited state species in biological processes, is not explicitly treated. The utilization of triplet excited carbonyl products to promote photochemical and photobiological transformations by energy transfer are of primordial interest and not the photomechanistic behavior, photophysical properties and inherent photochemical reactions of such excited state species. Thus, the coverage concentrates on photodamage of DNA and RNA, the photochemistry of flavins, vitamin D, tryptophan, arachidonic acid, chlorophyll, lipid peroxidation, urocanase activation, excitation of chlorophlasts, and the aerobic oxidation of Schiff bases derived from amino acids and proteins. The potential perspectives of employing authentic dioxetanes and enzymatically generated dioxetane intermediates as effective photon equivalents in photochemotherapy, phototoxicity, photoaffinity labeling and photogenotoxicity are pointed out, in the hope of stimulating more intensive activity in this emerging and novel bioorganic and photobiological field.     

Intramolecular silyl migration in the singlet oxygenation of 2-methyl-5-trimethylsilylfuran

Tetraphenylporphyrin-sensitized photooxygenation of 2-methyl-5-trimethylsilylfuran ($\text{4}$) affords quantitatively trimethylsilyl 2-oxo-4-pentenoate ($\text{5}$), presumably via intramolecular Baeyer-Villiger rearrangement of the intermediary dioxirane ($\text{3a}$).     

Thermal analysis and X-ray studies of chiral ferroelectric liquid crystalline materials and their binary mixtures

Summary Thermal properties of a homologous series of ferroelectric liquid crystals S-(-)-[4-(2-n-alkoxy-propionyloxy)]biphenyl-4'-[n-alkoxy-(3,5-dimethyl)]benzoate have been investigated by polarizing optical microscopy and differential scanning calorimetry. The mesophases were identified and confirmed by X-ray too. Three binary mixtures were prepared from the individual homologues. In one of the mixtures (Mix1), the ferroelectric SmC* phase has broadened and became enantiotropic. This mesophase remained monotropic in the other two mixtures (Mix2, Mix3). The chiral nematic N* phase did not appear in Mix1, but remained monotropic for the other two mixtures. Two molecular parameters, the layer spacing and the average intermolecular distance have been calculated from the X-ray results for the homologues and their mixtures. An intercalated tail-to-tail packing of molecules was found both in the single compounds and their mixtures resulting in the layer spacing about half of the molecular length of the single compounds.     

The second order optical potential for theπd system at the threshold

The second order optical potential for thed system is derived in the framework of the Watson formalism and applied to the calculation of the 1s-state energy shift of the atom and thed scattering lengtha _d . The results are in good agreement with those of the Faddeev type calculations.The authors wish to thank V. B. Belyaev, R. Mach, M. G. Sapozhnikov and R. A. Eramzhyan for stimulating discussions and helpful advice.     

Analytical Detectors Based on Microplasma Spectrometry

Miniaturizing all dimensions of apparatus, such as electronics and computers, is the current trend followed by scientists in various fields. The idea of Lab-on-a-Chip has significantly expanded and found its broad applications in analytical chemistry. Microplasmas can act as a sample excitation source and are the miniaturized versions of full-sized plasmas. These can be created in various forms, such as direct current, microwave induced, capacitively coupled and inductively coupled plasmas. Scaling down the size would reduce the amount of gases, liquids and consumables required, as well as the sample analysis time, which in turn would decrease the operating costs. Therefore, several research groups are involved in the development of microplasmas for utilisation in analytical instruments.     

The effect of chain structure on the annealing and deformation behaviour of polymers

Summary In a tensile test ductile thermoplastics may give either uniform deformation or necking. Recently it has been found that those giving uniform deformation either, are known to have extended chain configurations in solution, or have chemical formulae with linear structures and relatively few flexible bonds. The observed differences in behaviour can be predicted from a viscosity retarded rubber elasticity model in which a constant related to chain flexibility is introduced, which quantifies the strain hardening of the material. It is argued that the early development of strain hardening generally interferes with the localization of plastic strain in shear bands or crazes (as well as in a neck) and correlates with the stress cracking performance of high density polythenes.There is now also some evidence that polymers with extended chain configurations have small values ofcp (the change in specific heat atTg) and that this figure has an apparent correlation with draw ratio for different polymers.In the case of P.V.C. however it is possible to cause a changeover from the normal necking behaviour to uniform deformation by quenching the hot material in ice water. This process is believed to eliminate a structure which develops slowly in P.V.C. and most other thermoplastics when they are annealed at temperatures near toTg. The elimination of this structure during yielding causes strain softening and also promotes plastic strain localisation.This physical ageing or annealing process is still not well understood. It almost certainly includes free volume effects but recent studies have shown that a redistribution of rotational isomers also occurs. These observation, if correct, have fundamental implications for the physics of glassy polymers.

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Zusammenfassung Beim Zug-Test erfolgt bei dehnbaren Thermoplasten entweder eine gleichmäßige Deformation oder eine Einschnürung. Erstere tritt auf bei Vorliegen ausgestreckter Kettenkonfigurationen in Lösung oder bei Makromolekülen linearer Struktur und relativ unbiegsamer Bindungen. Die beobachteten Unterschiede wurden anhand eines ViskositätsModells mit verminderter Gummi-Elastizität unter Zugrundelegung von Literaturdaten diskutiert. Die Kettensteifheit wird rechnerisch durch Einfügung einer Konstanten berücksichtigt; sie steht in Konkurrenz mit der Lokalisierung der plastischen Dehnung und korreliert mit dem Auftreten einer Spannungsriß-Bildung im Polyäthylen hoher Dichte. Es wird darauf hingewiesen, daß sich die spezifische Wärme von Polymeren mit ausgedehnter Kettenkonfiguration beiTg nur wenig ändert; dieser Effekt steht mit dem Dehnungsverhältnis verschiedener Polymerer in Einklang.Bei PVC kann jedoch durch Abschrecken des heißen Materials in Eiswasser ein Übergang vom normalen Einschnürungsverhalten zu einer gleichmäßigen Deformation erzielt werden; dieser Effekt ist durch die Unterdrückung einer speziellen Struktur bedingt und kann auch bei der Temperung anderer thermoplastischer Polymerer nahe beiTg auftreten.Die sich bei der physikalischen Alterung und bei der Temperung abspielenden Vorgänge lassen sich noch nicht erklären. Sie umfassen sicherlich Effekte des freien Volumens und die Rückverteilung von Rotations-Isomeren. Beobachtungen dieser Art sind von grundsätzlicher Bedeutung für die Physik glasartiger Polymerer.

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Dedicated to Prof. Dr. Rehage on the occasion of his 60th birthday.

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With 22 figures and 2 tables