Pseurotin B,C, D,and E. Further New Metabolites of Pseudeurotium ovalis STOLK

The structures 2–5 are assigned to the pseurotin B, C, D and E, which are new metabolites of Pseudeutorium ovalis STOLK , based on spectroscopic data and chemical transformations.     

PHYTOCHROME-MEDIATED CONTROL OF PROLAMELLAR BODY REORGANIZATION AND PLASTID SIZE IN MUSTARD COTYLEDONS

Abstract— The development of plastids in the palisade parenchyma cells of the cotyledons of mustard seedlings ( Sinapis alba L.) was studied by electron microscopy. In darkness the etioplasts undergo a sequence of morphogenic changes previously recognized in principle in bean and barley leaves, as summarized by Rosinski, J. and W. G. Rosen (1972) Quart. Rev. Biol. 47 , 160–190. From 12 to 36 h after sowing, an increase in the percentage of etioplast profiles with paracrystalline prolamellar bodies can be observed. Thereafter, the degree of organization and size of the prolamellar bodies decrease. 60 h after sowing, the etioplasts show only remnants of prolamellar bodies with irregularly spaced tubules. Continuous far-red light, which is considered to operate via phytochrome, counteracts the decay of organization of the prolamellar body and strongly increases the size of the plastids. The effect of continuous far-red light (onset of light 36 h after sowing) can be substituted by 12 h of far-red light given between 36 and 48 h after sowing. It is shown with red and far-red light pulses that the morphogenic effect of long-term far-red light on plastid size and appearance of the prolamellar body is exclusively due to phytochrome (P_fr). Changes by light in the amounts of protochlorophyll(ide) or chlorophyll(ide) do not affect these results. The action of P_fr on the structure of the prolamellar body is a relatively fast process, occurring within 3 h. Formation of thylakoids does not seem to be under phytochrome control. Rather, this response seems to be related to the protochlorophyll(ide)→ chlorophyll(ide) a transformation.     

Das Eigenwertproblem für eine reelle nichtselbstadjungierte elliptische Differentialgleichung zweiter Ordnung

Zusammenfassung Es handelt sich um das Eigenwertproblem für eine nichtselbstadjungierte partielle Differentialgleichung vom Typ der Schwingungsgleichung. H. Geppert zeigte1928, daβ in Falle des Verschwindens der Randwerte ein reeller Eigenwert existiert. T. Carleman bewies im einer grundlegenden Arbeit aus dem Jahre1936, daβ die i.a. komplexen Eigenwerte, wenn sie in unendlicher Anzahl auftreten, demselben asymptotischen Gesetz wie im selbstadjungierten Fall genügen. Wir zeigen im Folgenden, daβ unendlich viele Eigenwerte existieren. Entrata in Redazione il 7 ottobre 1970.     

Further Syntheses of Optically Active Verrucarinic Acid, 43rd Communication of Verrucarins and Roridins

Two new syntheses of verrucarinic acid (2S, 3R-dihydroxy-3-methylpentanoic acid) and its derivatives, suitably protected for the further conversion to macrocyclic trichothecenes, are described. The first one makes use of a diastereoselective alkylation of a (?)-(S)-malic acid ester and the regioselective reductin of one carboxyl function toa methyl group. The second approach involves a stereoselective addition of an allylsilane to a chiral glyoxylate.     

Styrofoam calorimeter for high energy CO2 lasers

A simple calorimeter that has been used to measure pulse energy and energy distribution of a pulsed gas-dynamic laser is described. The pulses had an energy density 10 J cm^-2 and width 0.1 s. Energy is determined from the volume of styrofoam melted by the pulse. Results showing the linearity of the method are given.     

Zur Bestimmung der kritischen Micellbildungskonzentration von Polyäthylenoxiden durch pH-Wert-Messung

Colloid and Polymer Science - Die kritische Mizellbildungskonzentration von Polyäthylenoxiden wurde durch pH-Wert-Messungen bestimmt. Die Ergebnisse wurden mit der Bildung eines...     

A micro-reactor for preparing uniform molecularly imprinted polymer beads

In this study, uniform spherical molecularly imprinted polymer beads were prepared via controlled suspension polymerization in a spiral-shaped microchannel using mineral oil and perfluorocarbon liquid as continuous phases. Monodisperse droplets containing the monomers, template, initiator, and porogenic solvent were introduced into the microchannel, and particles of uniform size were produced by subsequent UV polymerization, quickly and without wasting polymer materials. The droplet/particle size was varied by changing the flow conditions in the microfluidic device. The diameter of the resulting products typically had a coefficient of variation (CV) below 2%. The specific binding sites that were created during the imprinting process were analysed via radioligand binding analysis. The molecularly imprinted microspheres produced in the liquid perfluorocarbon continuous phase had a higher binding capacity compared with the particles produced in the mineral oil continuous phase, though it should be noted that the aim of this study was not to optimize or maximize imprinting performance, but rather to demonstrate broad applicability and compatibility with known MIP production methods. The successful imprinting against a model compound using two very different continuous phases (one requiring a surfactant to stabilize the droplets the other not) demonstrates the generality of this current simple approach.     

Functional liquid crystal films selectively recognize amine vapours and simultaneously change their colour

During recent years, cholesteric liquid crystals have found only a few applications, one of them being temperature detection; in this study, however, we intend to show that the combination of cholesteric liquid crystals and molecules with a trifluoroacetyl function can be applied to optically detect amine vapours.