Elements in the history of the Periodic Table.
Discovery of the Periodic Table was rendered possible only after four decisive prerequisites had been achieved. These were (i) the abandonment of the metaphysical and occult notions of elements that typified the alchemical era; (ii) the adoption of a modern and workable definition of an element; (iii) the development of analytical chemical techniques for the isolation of the elements and determination of their properties; and (iv) the devising of a means of associating each element with a characteristic natural number. The Periodic Table made its appearance on cue almost as soon as these preconditions had been fulfilled.
Off-energy-shell phase shifts in potential scattering
SummaryA method for calculating off-energy-shell partial-wave amplitudes in potential scattering is presented. The method is analogous to the procedure of extracting a phase shift from the asymptotic form of a wave function, and avoids the use of integral equations. The usual on-shell procedure is generalized by introducing the idea of an off-energy-shell phase shift. Both the off-shellT-matrix and the off-shellK-matrix can be calculated in this way. It is shown that the slope of a resonance form factor is simply related to the derivative of the off-shell phase shift at the resonance.RiassuntoSi presenta un metodo per calcolare le ampiezze di onda parziale fuori dello strato delle energie nello scattering di potenziale. I1 metodo è analogo al procedimento per ricavare uno spostamento di fase dalla forma asintotica di una funzione d'onda, ed evitare l'uso di equazioni integrali. Si generalizza l'usuale procedimento sullo strato introducendo l'idea di uno spostamento di fase fuori dello strato delle energie. In questo modo si possono calcolare sia la matriceT fuori strato che la matriceK fuori strato. Si mostra che la pendenza di un fattore di forma di una risonanza è in semplice relazione con lo spostamento di fase fuori strato alla risonanza.
Denitrification of PVA-immobilized denitrifying photosynthetic bacterium, Rhodobacter sphaeroides
Abstract A newly isolated denitrifying strain, Rhodobacter sphaeroides NII2 was immobilized in polyvinyl alcohol (PVA) gel, and the properties of the cells in the gel were examined. The immobilized cells had low or almost no denitrification activity, but the cells were activated by incubation in light with culture medium for denitrification containing 0.5% nitrate and no other nitrogen source. Cells grown in the dark were activated by incubation at an earlier stage and to a higher rate than the light-grown cells. The activation was markedly enhanced in the PVA gel with a low cell concentration. The immobilized cells consumed nitrate with a temporary accumulation of NO 2 and evolved nitrogen gas. The immobilized cells could use various organic compounds as electron donors for denitrification. Thus, the immobilized cells were applied to a continuous treatment of synthetic wastewater using an aparatus devised by this laboratory. The results showed an efficient removal of NO 3 -N from the test water.