Encapsulation of pesticides in a starch-calcium adduct

A simple method of encapsulating water-insoluble pesticides in a starch matrix is described. The method consists of mixing the pesticide with alkali starch followed by precipitation with a calcium chloride solution. A starch–calcium adduct that entraps the pesticide in small cells within granular particles is formed. Liquid and solid pesticides were successfully encapsulated by the new method. By use of the herbicide trifluralin [2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl) benzenamine] as core material more than 90% recovery and encapsulation was achieved. Use of acid-modified starches and flours resulted in a lower percentage of encapsulation. Effective encapsulation was also achieved by replacing calcium chloride with strontium chloride or barium chloride.     

H and c NMR study of phosphopeptides : I—Acetylphosphoserine and acetylphosphothreonine

The ¹H and ¹³C NMR spectra of acetylserine, acetylphosphoserine and acetylphosphothreonine have been measured and completely analysed as a function of pD. For pD> 4 the NMR parameters are only slightly pD dependent. The second titration step of the phosphate group (pK₂ = 6.5) is much more difficult to detect in AcPSer (AcPTher) than in PSer (PThr). The ionization of the phosphate is of minor direct influence on the NMR parameters, their comparatively much larger changes in PSer (PThr) are due to conformational changes caused by the electrostatic interaction between the amino and phosphate group. The conformation in which the atoms H-C-Cβ-O-P form a planar W-type arrangement predominates at all pD values in the studied region from 4 to 14 in contrast to the non-cetylated phosphoamino acids in which its percentage passes a minimum at pD 8.     

Dual fluorescence (S1, S2) in chrysene and 3,4-benzophenanthrene

S₂ and S₁ fluorescence of chrysene and 3,4 benzophenanthrene has been observed in the vapour phase under collision free conditions. It is shown that the intermediate strong couplinng model can be applied to these molecules. The efficiency of the transfer of the excess energy to collision partners is given for different gases.     

Repair of furocoumarin-plus-UVA-induced damage and mutagenic consequences in eukaryotic cells

In the presence of near-UV radiation (UVA) furocoumarins (psoralens) photoinduce defined lesions in DNA, i.e. monoadducts and interstrand crosslinks. Their use in photochemotherapy (psoralen plus UVA (PUVA) treatment) and cosmetics raises questions concerning the repairability of these lesions and their genotoxic consequences. We have analysed the repair of psoralen photoadducts in cultured eukaryotic cells, such as yeast and mammalian cells, for furocoumarins of photochemotherapeutic interest. In yeast, the interaction of repair pathways differs in exogenous (plasmid) and endogenous (chromosomal) DNA. The order of mutagenic activity is 4,5',8-trimethylpsoralen greater than 5-methoxypsoralen greater than 8-methoxypsoralen greater than 7-methylpyrido[3,4-c]psoralen greater than 3-carbethoxypsoralen. The mutagenicity is dependent on psoralen functionality, concentration and bioavailability, maximal UVA dose, wavelength, dose (fluence) rate and presence or absence of chemical filters. It probably involves an inducible component. Chromosome breakage occurs during the repair period after PUVA treatment. It appears that the genotoxic effects of psoralens are produced by a specific arrangement of induced photolesions and the interaction of different repair systems.     

Structure of the alkaloid kalidine

The spatial structure of the alkaloid kalidine obtained from the epigeal part ofKalidium gracile Fenzl. has been determined by IR and NMR spectroscopy and x-ray structural analysis. It has been established that it is the chloride of the trimethyl derivative of glycinamide.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 558–561, July–August, 1987.     

Anwendung von Ionenaustauschern in der analytischen Chemie

Zusammenfassung In vorliegender Mitteilung wurde gezeigt, da\ durch Beachtung der Korngrö\e des Ionenaustauschers die Arbeitsbedingungen wesentlich vereinfacht werden können, was sich auch sehr in der Trennzeit bemerkbar macht. Unter Bezugnahme auf frühere Mitteilungen werden allgemeine Richtlinien für quantitative Trenneffekte bei Konzentrationsunterschieden der zu trennenden Elemente angegeben und in einer Tabelle werden sÄmtliche Möglichkeiten der Zweifachtrennungen aufgeführt. Die Differenz bzw. der Quotient der Elutionskonstanten E _l ¹ und E _e ² gestatten, zahlenmÄ\ig den Trenneffekt zu beurteilen.Die aus der Praxis aufgeführten Beispiele quantitativer Trennungen zeigen, welchen Nutzen heute Ionenaustauscher in der analytischen Chemie haben können.Für die sorgfÄltigen Ausführungen der Messungen bin ich FrÄulein Fickel und Herrn Kretzschmar zu Dank verpflichtet.     

A short synthesis of the erythrina skeleton and of (+/-)-alpha-lycorane

[reaction: see text] A new nonchain 5-endo radical cyclization starting with xanthates was exploited in a short synthesis of (+/-)-alpha-lycorane and the erythrina ring system.     

Catecholamine binding to CNS adrenergic receptors.

The properties of 3H-catecholamine binding to alpha- and beta-adrenergic receptors in CNS are reviewed. 3H-epinephrine and 3H-norepinephrine label one class of alpha-receptors throughout the brain, with high affinities for agonists and some antagonists. Agonist affinities at this site are increased in low temperature conditions but are reduced by guanine nucleotides and monovalent cations. Divalent cations reverse both effects. This alpha-receptor may be coupled to adenylate cyclase by GTP and/or sodium, and uncoupled by divalent cations. 3H-epinephrine labels beta2, but not beta1, receptors in CNS, especially in bovine cerebellum. The same beta-receptor does not show agonist-specific GTP-sensitivity, but does exhibit Na+-sensitivity. This receptor appears to be linked to adenylate cyclase, and sodium rather than GTP may be the coupling agent.