LIGHT-INDUCED CHEMOTACTIC REACTIONS IN THE DINOFLAGELLATE, Peridiniopsis berolinensis

Abstract The photosensitizer riboflavin induces accumulation of the colorless flagellate Peridiniopsis berolinensis in a light field at low photon fluence rates but dispersal from a light field at high photon fluence rates. The wavelength dependence of the accumulation resembles the absorption spectrum of riboflavin in the visible range. The photodynamic effects are caused by a positive or negative chemotactic response to photoproducts in the medium which are produced by photochemical reactions of the dye.     

Development of pork fat reference material for OCPs BCR-CRM 430

Summary A pork fat sample was prepared and tested as candidate reference material for 10 organochlorine pesticides and metabolites (OCPs): hexachlorobenzene, -, - and -HCH, -heptachlor epoxide, dieldrin, endrin, p,p'-DDT, p,p'-TDE and p,p'-DDE. Preparation and testing for homogeneity and stability of the OCPs in the pork fat are discussed. The coefficient of variation of pesticide determinations carried out to test the between-ampoule homogeneity ranged from 2.4–5.8% and was found to be very similar to that for the analytical method (2.5–4.9%). This means that the homogeneity is very good. Stability data over 12 months do not show any trends that suggest lack of stability.     

The molecular structure of cis- and trans-1,2-difluoro-ethene: An electron diffraction study

The molecular structure of cis- and trans-1,2-difluoroethene was studied in the gas phase by electron diffraction, using the sector-microphotometer technique. The molecules are planar. For trans-difluoroethene the geometrical parameters are: C-F bond: 1.338(0.003) Å; CC bond: 1.320(0.009) Å; C-H bond: 1.088(0.004) Å, ∠CCF 119.8°(0.2°); ∠CCH: 125° (1.2°). For cis-difluoroethene: C-F bond: 1.332(0.003) Å; CC bond: 1.311(0.008) Å; C-H bond: 1.100(0.003) Å; ∠CCF: 122.5°(0.2°); ∠CCH:127.0 °(2.3°).     

Secondary metabolites of the coelenterate echinopora lamellosa

The marine coelenterate Echinopora lamellosa (class Anthozoa, family Scleractinidae) was found to contain a number of unprecedented secondary metabolites which were isolated and identified as smilagenin (I), neodunol methyl ether (II), glycyrrhetic acid (III), 3β-acetoxyglycyrrhetic acid (IV), and 3β-acetoxy-11-deoxoglycyrrhetic acid (V). The structure of neodunol methyl ether was confirmed and its absolute configuration determined by the x-ray diffraction method.     

Hyperfine structure of the 625 nm band in the a 3Πu ← X 1 Σg transitions of Na2

Hyperfine structures of transitions in the a ³Π_u ← X¹Σ_g system of Na₂ have been accurately measured by Doppler-free laser excitation spectroscopy in a collimated molecular beam. The hyperfine patterns are quantitatively explained and the reduced matrix elements of the magnetic dipole hf interaction determined from a least-squares fit to the measured line positions.     

Purification of adipoyl-7-amino-3-deacetoxycephalosporanic acid from fermentation broth using stepwise elution with a synergistically adsorbed modulator

Multicomponent adsorption data of a fermentation broth containing adipoyl-7-amino-3-deacetoxycephalosporanic acid (adipoyl-7-ADCA), a cephalosporin precursor for 7-ADCA, and two key impurities, alpha-hydroxyadipoyl-7-ADCA and alpha-aminoadipoyl-7-ADCA were obtained from batch equilibrium and frontal chromatography tests. Amberlite XAD-1600 was chosen as the resin. A rate model was applied to simulate the chromatograms. An alkaline buffer, which by itself has no affinity for the resin, was used as the eluent. The widely used reversed-phase modulator model is inaccurate in explaining the stepwise elution data. A new model, the induced competition model, has been developed to account for apparent retention of the buffer in the presence of adsorbed species. Close agreement between the simulations and the data was achieved with the new model.     

Anisotropic muon Knight shift in the HCP single crystals of Cd,Zn and Be

In single crystal samples of Zn, Cd and Be (hcp structure) stroboscopicSR measurements successfully revealed anisotropies in the muon Knight shift (K). An anisotropic K can provide information on the amount of non s-electrons screening the charge of the muon implanted in these metals as a light hydrogen isotope. In Cd, the anisotropic part depends strongly on the temperature and shows a change in sign at roughly 110 K. In Zn, the anisotropic part below 10 K turns out to comprise 4th order contributions in the direction cosines of the external field. This can be understood on the basis of an anisotropicg-factor of the conduction electrons or spin-orbit coupling, respectively.     

Stable gaseous aziridinium ions

Gaseous protonated aziridine ions are produced at the threshold from β-phenoxyethylamine molecular ions. The evidence for this is collisional activation spectra, using various precursors (including labelled analogues) under electron impact and field ionization conditions. Partial conversion to the acyclic \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_{\rm 3} {\rm CH = }\mathop {\rm N}\limits^ + {\rm H}_{\rm 2} $\end{document} isomer occurs at higher electron energies and is rationalized by means of a potential energy surface constructed from energetic data.