Hemmung der aktiven Bromidaufnahme durch Pflanzenzellen durch Glucose

Zusammenfassung Die Aufnahme von Bromid-Ion durch Chlorella pyrenoidosa, die durch aktiven Transport erfolgt, wird durch Glucose gehemmt, obwohl die Atmung stimuliert wird. Die Hemmung tritt bei Energielieferung durch Belüftung oder Belichtung ein. Galactose und Mannit wirken nicht wie Glucose. Offenbar hemmt die Glucose die Nutzbarmachung des Elektronenflusses bei dem System der Atmung oder Photophosphorylierung für die Bromid-Aufnahme.

---

The absorption of bromide ion by chlorella pyrenoidosa, which is due to active transport, is inhibited by glucose though respiration is stimulated. Inhibition is observed when energy is supplied either by aeration or by illumination. Galactose or mannitol do not act like glucose. Apparently glucose interferes with the utilization of electron flow in the respiration or photophosphorylation systems for the absorption of bromide.

---

---

Mit 3 Abbildungen.

---

Herrn Prof. Dr.F. Wessely zum 70. Geburtstag in Verehrung gewidmet.     

Änderungen der Kationenaustauschkapazität und des Gitters einiger Biotite bei Behandlung mit synthetischen Kationenaustauschern

Zusammenfassung Vor und nach Behandlung drei verschiedener Biotite mit H⁺-, Li⁺-, Na⁺- und K⁺-beladenem Ionenaustauscher (Amberlite Resin IR-120, Standard Grade) wurden deren Kationenaustauschkapazität gemessen und deren Röntgendiffraktionskurven aufgenommen. Nach Behandlung mit H⁺-, Li⁺- und Na⁺-beladenem Ionenaustauscher ergibt sich eine deutliche Steigerung der Kationenaustauschkapazität und eine Gitterstörung in Richtung auf Vermiculit. K⁺-beladener Ionenaustauscher hat jedoch nur sehr kleine Änderungen verursacht. Es scheint, als ob, je größer das Verhältnis Fe/Mg in einem Biotit ist, um so weniger wird er durch Behandlung mit dem verwendeten kationenbeladenen Ionenaustauscher verändert. Eine Erklärung dieser Erscheinung wird vorgeschlagen, Kontaktzeit und Verhältnis zwischen Ionenaustauscher und Mineral spielen eine wesentliche Rolle für die Veränderungen der Biotite.     

Zur Aktivierung partiell silylierter Kohlenhydrate mittels Triphenylphosphan/Azodicarbonsäureester

On the Activation of Partially Silylated Carbohydrates Using Triphenylphosphane/Diethylazodicarboxylate Reaction of methyl α-D-glucopyranoside ( 1 ) with two equivalents of t-butyldimethylchlorosilane yields methyl 2,6-bis[O-(t-butyldimethylsilyl)]-α-D-glucopyranoside ( 1a ) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-α-D-glucopyranoside ( 1b ) in a ratio of 4:1. The anomeric β-pyranoside 2 affords methyl 2,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside ( 2a ) and methyl 3,6-bis[O(t-butyldimethylsilyl)]-β-D-glucopyranoside ( 2b ) in nearly equal amounts. 2b is isomerized to methyl 4,6-bis[O(t-butyldimethylsilyl)]-β;-D-glucopyranoside ( 2c ) (83%) and 2a (10%) with triphenylphosphane/diethylazodicarboxylate. Structures were assigned by NMR.-analysis and CD.-analysis of the corresponding benzoates 1c , 1d and 2d and of the acetates 2e and 2f . 1a is transformed into methyl 4-azido-2, 6-bis[O(t-butyldimethylsilyl)]-4-deoxy-α-D-galactopyranoside ( 3 ) with triphenylphosphane/diethylazodicarboxylate/HN₃. 2a and 2c yield the 3-azido-allosides 5 and 7 respectively under similar conditions. The activation by triphenylphosphane/diethylazodicarboxylate is high enough to introduce also p-nitrobenzoate groups with inversion of configuration at the reaction center. By this way 1a and 2a give methyl 2, 6-bis[O(t-butyldimethylsilyl)]-4-O-p-nitrobenzoyl-α-D-galactopyranoside ( 4 ) and methyl 2, 6-bis[O-(t-butyldimethylsilyl)]-3-O?ptrobenzoyl-β-D-allopyranoside ( 6 ) respectively. For elucidation of structures the acetate derivatives 3a-7a were prepared.     

Infrared studies of chromones—II Isotopically substituted 5-hydroxychromones

By deuteration of the OH group, it has been shown that two bands, at 1665 and 1630 cm⁻¹ (CCl₄), in the IR spectra of 5-hydroxychromones are associated with the H-bonded CO stretching vibration. Nuclear deuteration of 5-hydroxy-2-methylchromone (1) under acidic conditions gave a tri- and a hexadeutero derivative; the latter, isotopically substituted at C-3, shows a single CO band at 1649 cm⁻¹. Hydrolysis of 3-acetyl-5-hydroxy-2-methylchromone with sodium carbonate in deuterium oxide furnished 5-hydroxy-2-trideuteromethylchromone-3-d which also exhibits a single CO absorption. Partial incorporation of O¹⁸ into the CO group of 1 results in a single ν_C=O¹⁸ at 1593 cm⁻¹. It is suggested that the doublet CO absorption of 5-hydroxychromones arises from a Fermi resonance involving a low-energy vibrational mode of the vinyl proton on the nuclear C-3 position.     

On the chromophore of polyacrylonitrile

Further evidence is presented to show that the chromophore of polyacrylonitrile is formed by polymerization of the nitrile groups, rather than by dehydrogenation of the polymer backbone. The polyimine structure formed is resistant to hydrolysis; hence, the nitrogen content of hydrolyzed polymer increases with increased chromophore formation.     

Plasma chromatography of heroin and cocaine with mass-identified mobility spectra.

Plasma chromatography detects and identifies compounds in trace quantities at atmospheric pressure through characteristic positive and negative mobility spectra. To facilitate use of the technique to detect gas chromatographic effluents, a number of reference mobility spectra for different classes of compounds have been reported. Reference spectra for two more compounds, heroin and cocaine, are presented in this study. The primary ions found in these mobility spectra were determined to be M+, (M - H2)+, and (M - CH3CO2)+ for heroin and M+, (M - C6H5CO2)+ and (M - C6H5CO2 - CO2CH3)+ for cocaine using a directly interfaced plasma chromatograph-mass spectrometer. The identified ions agree closely with those predicted in the ion mobility spectra using mass-mobility correlation data coupled with chemical ionization mass spectrometry data. Also, an independent check demonstrating the reliability of reduced mobility values reported in earlier reference spectra was made.     

Verdunstungsverluste aus der Preglschen Präzisionswägepipette über Phosphorpentoxyd

Zusammenfassung Präzisionswägepipetten nachPregl mit einem Inhalt von 1 ml eignen sich auch dann für die Dichtebestimmung von biologischen Flüssigkeiten, wenn man aus Gründen der Versuchsanordnung gezwungen ist, die gefüllten Pipetten vor der Wägung längere Zeit in einem Exsikkator über Phosphorpentoxyd aufzubewahren. Die eintretenden, zeitabhängigen Gewichtsverluste durch Verdunstung bleiben innerhalb der üblichen Fehlergrenzen.

---

Summary Precision weighing pipettes (afterPregl) with a capacity of 1 ml are suitable for determining the density of biological fluids, in case the experimental conditions require the storing of the filled pipettes for a considerable period, before weighing, in a desiccator over phosphorus pentoxide. The loss of weight due to evaporation is dependent on the waiting period but it remains within the usual limits of error.

---

Résumé Les pipettes de précision dePregl de 1 ml conviennent aussi pour la mesure de la densité de liquides biologiques quand on les maintient pleines avant la pesée un certain temps dans un dessiccateur sur l'anhydride phosphorique, lorsque l'ordre des expériences est déterminé. Les pertes de poids qui se produisent au cours du temps par évaporation restent au-dessous des limites habituelles d'erreur.

     

Syntheses, geometry optimization, and electronic structure of N-and C-substituted benzonaphthyridines

Synthesis of N-and C-substituted derivatives of benzo[h][1,6]naphthyridine, bearing 2-hydroxyethyl group has been made by quaternization reaction and by condensation of corresponding methylbenzonaphthyridines with formaldehyde. For six derivatives of isomeric benzo[c][1,5]-, benzo[h][1,6]-, and benzo[f][1,7]naphthyridines the ¹³C NMR spectra are discussed. For ten compounds the geometry was optimized with the AM1 and, in one case also with the ab initio 6–31G method; their effective charge values have also been calculated.     

Quantum scattering calculation of the O(1D)+HBr reaction

Three-dimensional time-dependent quantum wave packet calculation for the O((1)D)+HBr reaction has been carried out using an accurate ab initio global potential energy surface [K. A. Peterson, J. Chem. Phys. 113, 4598 (2000)]. The calculations show that the initial state-selected reaction probabilities are dominated by resonance structures, and the lifetime of the resonance is generally in the subpicosecond time scale. The energy dependence of the reaction cross section is computed, which manifests still resonance structures, and is a decreasing function of the translational energy. The thermal rate constants are also computed, which are nearly independent on the temperature. The calculation results are discussed and compared to similar reaction with deep well.