THE NON-RADIATIVE DISSIPATION OF EXCITATION ENERGY IN SOLID CINNAMIC ACID BY DIMER FORMATION

Abstract— The quantum efficiency for the photodimerization of trans -cinnamic acid in the solid state is independent of intensity and is found to have a value approaching two. Thus, the reaction involves one excited and one un-excited molecule.
During the exposure, a dimer film developing on the surface of the cinnamic acid layer attenuates the intensity of the radiation incident on the unreacted cinnamic acid. This gives the appearance of a decrease in the quantum yield with increasing number of photons incident.     

Über den Nachweis und die Bestimmung des Schädlingsbekämpfungsmittels E 605 in der gerichtlichen Chemie

Zusammenfassung Es wird gezeigt, daß sich Insektizide auf der Basis der Ester der Thiophosphorsäure (E 605) aus biologischem Material mittels Wasser-dampfdestillation auf verhältnismäßig einfache Weise abscheiden lassen. Im Destillat erfolgt die Bestimmung nach Ausäthern und Lösen des Rückstandes in Äthanol durch Messen der Lichtabsorption im UV. Hierbei zeigt sich, daß die rechnerische Eliminierung der Störstoffe bei geringeren Konzentrationen der Ester leichter ist als bei hohen.Durch Messung der Lichtabsorption im IR läßt sich, genügende Konzentration vorausgesetzt, entscheiden, welcher Ester vorliegt.

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Summary It was shown that insecticides based on the ester of thiophosphoric acid (E 605) can be separated in relatively simple fashion from biological material by means of steam distillation. The distillate is shaken out with ether and the residue dissolved in ethanol and the determination is accomplished by measuring the absorption in ultraviolet light. It was found that the computational elimination of the interfering materials is easier at lower concentrations of the ester than when higher concentrations are present. By measuring the light absorption in infrared, it is possible to decide which ester is present, provided the concentration is high enough.

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Résumé On montre que les insecticides se séparent d'une manière relativement simple de l'élément biologique par un entraînement à la vapeur d'eau sur la base de l'ester de l'acide thiophosphorique (E 605). Le dosage s'effectue sur le distillat d'après l'épuisement à l'éther et la solubilité du résidu dans l'éthanol et la mesure de l'absorption lumineuse dans l'ultraviolet. On en déduit que l'élimination calculée de la substance gênante est plus facile pour les faibles concentrations de l'ester que pour les grandes. En mesurant l'absorption de la lumière dans l'infrarouge, on peut savoir de quel ester il s'agit pour des concentrations supposées suffisantes.

     

Synthesis and characterization of poly-β-hydroxybutyrate. II. Synthesis of D-poly-β-hydroxybutyrate and the mechanism of ring-opening polymerization of β-butyrolactone

Synthesis of the naturally occurring polyester, D -poly-β-hydroxybutyrate (PHB) was accomplished by using an optically active monomer. Polymerization of D -(+)-β-butyrolactone (β-BL) of 73% optical purity with a catalyst system of Et₃Al–H₂O produced a polymer with a similar optical activity and essentially identical to the natural polymer as isolated from bacterial cells. This paper describes the synthesis and characterization of this optically active polyester along with a suggested mechanism to account for the observed stereospecific polymerization of β-BL with this catalyst system.     

3'-nitrophenylpropyloxycarbonyl (NPPOC) protecting groups for high-fidelity automated 5' --> 3' photochemical DNA synthesis

[structure: see text]. The most powerful DNA microarrays would be prepared by photolithography with free 3'-ends that could be processed enzymatically. A photoremovable group that could be removed in quantitative yield would ensure high purity of the synthesized probes. We have developed new pyrimidine building blocks for 5' --> 3' DNA synthesis with high cycle yields using the NPPOC (3'-nitrophenylpropyloxycarbonyl) protecting group. These phosphoramidites were proved in automated photochemical DNA synthesis on a modified synthesizer.     

The Effects of Beating,Web Forming and Sizing on the Surface Energy of <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> Kraft Fibres Evaluated by Inverse Gas Chromatography

In this work attention has been focused on the effects of papermaking beating, web forming and sizing operations on the physical/chemical surface properties of bleached Eucalyptus globulus kraft fibres. Inverse gas chromatography (IGC) was used to determine the dispersive component of surface tension (γ_s^d) as well as the acidic/basic character (according to the Lewis concept) of the solid surfaces (pulp fibres and pulp handsheets). The results have shown that the main effect of beating is to increase the fibre's Lewis acidic character. Web forming caused a strong decrease in γ_s^d and significant increments in the adhesion works of both acidic and basic probes, lowering the ratio between the two. Nevertheless, the surface of handsheets still exhibited a dominant acidic character. The sizing operation did not change the dispersive component of the surface tension significantly but decreased the difference between the adhesion works of the acidic and basic probes, rendering the handsheet surface less Lewis acidic and more Lewis basic. Thus, although internal sizing is expected to strongly influence liquid spreading at the paper surface and liquid penetration of the fibre's network, it is concluded that beating and web forming lead to important changes in the surface energetic properties of the Eucalyptus globulus kraft fibres.     

Séparation de traces de fluorure des sels d'aluminium(III) par échangeurs d'ions

A method is proposed for the separation of aluminium(III) fluoride by chromatographie by means of an anion exchanger in alkaline medium, The methode is applicable to a minimum of 100 p.p.m. of fluoride in the aluminium.     

Carbon-13 spin-lattice relaxation studies of the effect of water on ion-selective electrode membranes

(13)C spin-lattice relaxation studies on bis(2-ethylhexyl) adipate (DOA) plasticized poly(vinylchloride) (PVC) membranes are reported for plasticization levels ranging from 25 to 100 wt% plasticizer. The interaction between DOA and PVC molecules in these membranes appears to involve an entrapment of the plasticizer molecule within the polymer matrix. This is based on the constancy of the characteristic segmental motions of the plasticizer chains throughout the concentration range studied. The segmental mobility of the plasticizer component is modified by water absorption in the membrane. The pattern of characteristic segmental motions of the plasticizer is altered, the effect depending on the amount of added salt in the membrane. The results show water has a weak influence on the microviscosity of the membrane matrix.     

Chromatographic studies of corrosion sites in metallic materials

Many types of corrosion phenomena are controlled by the ionic composition of a small volume of solution at the surface. Localized corrosion and atmospheric corrosion are two examples in which < 1 μl of solution can cause dramatic damage. Ion chromatographic (IC) techniques have been used to analyze these solutions in order to gain a better understanding of the mechanisms which govern them. Two examples are presented. The presence of minor alloying elements at localized corrosion sites in two aluminum alloys has been demonstrated, indicating non-stoichiometric dissolution of the alloy during localized corrosion. In addition, IC analysis allowed the determination of the species responsible for the atmospheric corrosion failure of electrical connectors, including their likely origin.     

Kinetic study of the metalation of a polystyrene model compound by the secondary butyllithium-N,N,N′,N′-tetramethylethylene diamine complex

2.5-Diphenyl hexane, a model compound of polystyrene was metalated by a complex of secondary butyllithium and N,N,N′,N′-tetramethylethylene diamine in heptane. At various times, the lithiated dimer was quenched with deuterated methanol. The deuterated compound was examined by mass spectrometry and from the deuterium content, the degree of lithiation was determined. The effects of the concentration of styrene units, secondary butyllithium and diamine on the lithiation were studied at 20 C and ?20 C. The overall rate of metalation was first order with respect to the styrene units concentration and half-order with respect to sec. butylithium-TMEDA complex concentration. The kinetic results were explained by the presence at 20 C of the 1 4 complex (1 sec. BuLi 4 TMEDA) and at ?20 C of the 1–2 complex (1 sec. BuLi 2 TMEDA).     

High-performance size-exclusion chromatographic determination of the potency of biosynthetic human growth hormone products

A new high-performance size-exclusion chromatography method has been developed for the determination of potency of human growth hormone products. This method has been extensively validated and shown to correlate well with the hypophysectomized rat bioassay which has been used traditionally. The method is much more precise than the traditional bioassay and thus provides more reliable means of producing consistent biosynthetic human growth hormone batches.