In vivo total body chlorine measurements using prompt-gamma neutron activation analysis

Total body chlorine (TBC1) provides an estimate of extracellular water. We have examined the feasibility of measuring TBC1 using the 5.6, 6.1, and 8.6 MeV C1 peaks produced during in vivo prompt-gamma neutron activation (dose<0.3 mSv). In subjects, background interference permitted the use of only the 8.6 MeV peak in C1 analysis. Preliminary analyses of the prompt-gamma spectra for 33 healthy females (ages: 24–40 yr) provided a mean estimate of 0.85 g C1 per kg body weight. It is therefore feasible to measure TBC1 concurrently with body nitrogen using relatively low-dose prompt-gamma neutron activation analysis.     

The effect of the source pressure on the abundance of ions of noncovalent protein assemblies in an electrospray ionization orthogonal time-of-flight instrument

The effect of elevating the pressure in the interface region of an electrospray ionization orthogonal time-of-flight mass spectrometer on the ion intensity of different noncovalent protein assemblies has been investigated. Elevating the pressure in the interface region generally led to an enhanced detection of high m/z ions. The optimum pressure was found to be dependent on the m/z value of the ions. This pressure effect should be carefully addressed when relating ion abundance in the mass spectra to solution phase abundance of noncovalent protein assemblies.     

Facile chemoselective synthesis of dehydroalanine-containing peptides

Useful methodology is described for the synthesis of dehydroalanine residues (II) within peptides. The unnatural amino acid (Se)-phenylselenocysteine (I) can be incorporated into growing peptide chains via standard peptide synthesis procedures. Subsequent oxidative elimination affords a dehydroalanine at the desired position. The oxidation conditions are mild and tolerate functionalities commonly found in peptides, including variously protected cysteine residues. To illustrate its utility, cyclic lanthionines have been synthesized by this method.     

A ten-residue fragment of an antibody (mini-antibody) directed against lysozyme as ligand in immunoaffinity chromatography

The interaction between an antibody molecule and a protein antigen is an example of "natural" protein modelling. Amino acids of the antigen-binding site consisting of three hypervariable segments (L1, L2, L3) of the light (L) and three (H1, H2, H3) of the heavy (H) chain of an antibody molecule interact with amino acids present in an epitope of a protein. A ten-residue peptide was synthesized with an amino acid sequence analogous to the hypervariable L3 segment of a monoclonal antibody directed against lysozyme. The peptide was immobilized on CH-Sepharose 4B and the affinity adsorbent was used to purify lysozyme added to a detergent extract of insect cells infected with a recombinant baculovirus. This methodology may also be applicable to other antigen-antibody combinations, in immunoaffinity chromatography for selective purification of a protein or in an immunosensor for detection of a protein.     

Utilisation d'un “blanc interferences” dans la determination des nitrates par potentiometrie selective

(Use of an interference blank in the determination of nitrate by ion-selective potentiometry.) During selective potentiometry of nitrate in meat product additives, a new interference originating from polyphosphate ions was encountered. The selectivity coefficients measured were 5 × 10^?2 for tripolyphosphate, 10^?2 for chloride, 8 × 10^?4 for pentapolyphosphate and 6 × 10^?4 for pyrophosphate. An “interference blank” techniques is proposed; nitrate is destroyed in the medium to be studied, so that calibration is possible in the presence of interfering substances regardless of their identity or concentration. The method is successfully applied to monitoring of meat product additives.     

1-Alkoxy-2-azaallenyl-komplexe von chrom und wolfram

The successive reaction of (CO)₆M with Na[NCR₂¹] and [Et₃O]BF₄ yields (CO)₅M[C(NCR₂¹)OEt] (II: M = Cr; III: M = W; CR₂¹ = C(C₆H₄Br-p)₂ (a), CPh₂ (b), C(C₆H₄OMe-p)₂ (c), C(C₆H₄)₂O (d), CBu₂^tt (e)). Hexacarbonyltungsten, (CO)₆W, reacts with Na[NCPh₂] and MeOSO₂F to give (CO)₅W[C(NCPh₂) OMe] (IV). X-Ray analysis of IIe shows that: (1) the CNC fragment is almost linear (171.7°); (2) the two NC bond lengths are equal within experimental error; and (3) the O,C,Cr,N plane is perpendicular to the C(Me₃),C,N,C(Me₃) plane (90.0°). Therefore compounds II–IV are best described as 1-alkoxy-2-azaallenyl complexes.     

Calorimetric,dilatometric and microscopic investigations of the system sodium stearate-stearic acid

Summary AT-x phase diagram of the system sodium stearate (NaSt)-stearic acid (HSt) has been determined by DTA. It shows the existence of five defined association compounds, three of them (2 NaSt · 3 HSt, NaSt · HSt and 3 NaSt · 2 HSt) with an incongruent melting point and the others (5 NaSt · 2 HSt and 5 NaSt · HSt) with a congruent melting point. The latter two compounds pass through various mesomorphic phases before melting. The components do not form solid solutions and are even non-miscible in the mesomorphic state below 200 °C. Mutual miscibility is only observed above this temperature in the subneat and neat region, occurring in the HSt composition range from 0 to 15 and from 0 to 5 mole% respectively. The existence of molecular associations in the liquid state is very probable, particularly in the composition range between 30 and 40 mole% stearic acid. This might result in a liquid structure similar to that present in the melt of anhydrous soaps.

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Zusammenfassung EinT-x Zustandsdiagramm des Natriumstearat (NaSt)- Stearins?ure (HSt)-Systems wurde mittels DTA bestimmt. Es weist fünf definierte assoziierte Verbindungen auf, drei (2 NaSt · 3 HSt, NaSt · HSt und 3 NaSt · 2 HSt) mit einem inkongruenten Schmelzpunkt und zwei (5 NaSt · 2 HSt und 5 NaSt · HSt) mit einem kongruenten Schmelzpunkt. Die zwei letzteren Verbindungen durchlaufen verschiedene mesomorphe Phasen, bevor sie schmelzen. Die Komponenten bilden keine festen L?sungen und sind im mesomorphen Zustand unter 200 °C nicht einmal miteinander mischbar. Nur bei h?heren Temperaturen sind sie v?llig mischbar, und zwar in der “subneat” und “neat” Region, die im HSt-Bereich von 0 bis 15 bzw. von 0 bis 5 Mol% reicht. Die Existenz molekularer Assoziate im flüssigen Zustand ist sehr wahrscheinlich, vor allem im Bereich zwischen 30 und 40 Mol% Stearins?ure. Dies k?nnte zur Bildung von Strukturen in der Flüssigkeit führen ?hnlich, wie dies bei der Schmelze wasserfreier Seifen der Fall ist.

     

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.