Separation of sodium and potassium by ion-exchange on cellulose phosphate

(24)Na and (42)K can be separated by ion-exchange chromatography with 80% methanol-2M hydrochloric acid on an 80 x 6mm column of cellulose phosphate. On cellulose phosphate paper the R(f) values are 0.63 for Na and 0.40 for K.     

Trace analysis by microwave excitation of sealed samples-I: preliminary investigations

An important limitation to the sensitivity of analytical methods using atomic spectroscopy is the short residence-time of the atoms in the light-path. The possibility has been studied of sealing the samples in a quartz tube where they are forced to emit light by microwave excitation. The detection of amounts below one ng in a volume of 0.5 ml seems possible.     

Dynamische Betrachtungen von Kontakt winkelmessungen an adsorbierten Proteinschichten

Ohne Zusammenfassung     

The addition of methylborylene to acetylenes

The synthesis of alkyl-substituted 1,4-dimethyl-1,4-diboracyclohexa-2,5-dienes from dialkylacetylenes and the system C₈K/MeBBr₂ is described.     

Transferability of dipole moment derivatives: Calculation of absolute rotational contributions for symmetrical molecules

It is shown that Polo's method for the calculation of the D^?1 and G^?1 matrices can be extended to the calculation of the absolute rotational contributions involved in the molecular dipole moment derivatives in terms of symmetry coordinates. The method applies to both stretching and bending modes. The method is outlined for AB₃ (C_3v) molecules.     

Synthesis of quinoline and benzo[b]thiophene derivatives by ring annelation of pyridines and thiophenes

Selected ortho-disubstituted pyridines and thiopenes react with Michael acceptors to give functionalized quinolines or benzo[b]thiopenes, respectively.     

Measurements of the second-sound velocity in dilute 3He4He mixtures

A Helmholtz resonator was used to measure the velocity of second sound in dilute solutions of ³He in ⁴He. The results are compared with values reported by Brubaker et al. and de Voogt et al.     

An M/G/1 queueing model with vacation times

This paper deals with an M/G/1 queueing system with finite capacity for the workload, where the workload at timet is defined as the total amount of work in the system at timet. When the server provides service he will continue servicing until the system becomes empty, after which he leaves the system for a stochastic period of time, which will be called a vacation. When the server, returning from a vacation, finds the system still empty, he leaves for another vacation, otherwise he immediately starts servicing again.Using an embedding approach several characteristics of this system are derived amongst which the joint stationary distribution of the workload and the stage of the server.

---

Zusammenfassung Diese Arbeit befaßt sich mit einem M/G/1 Wartesystem, das hinsichtlich der anstehenden Arbeit eine endliche Kapazität hat. Wenn der Bediener tätig ist, bleibt er es solange, bis das System leer ist. Danach ist er während einer stochastischen Pausenzeit nicht verfügbar. Ist am Ende einer Pausenzeit das System immer noch leer, so schließt sich eine weitere Pausenzeit an; ansonsten wird unverzüglich die Bedienung am Ende der Pausenzeit wieder aufgenommen.Unter Verwendung eines eingebetteten Prozesses werden mehrere Kenngrößen des Systems ermittelt, darunter z.B. die gemeinsame Verteilung von anstehender Arbeit und Zustand des Bedieners.