The electronic structure of Rhodium: Angle-resolved studies of photoelectron and secondary electron emission

We report electron spectroscopic studies of the Rh(111) surface, with the aim to obtain bulk band-structure information. We have measured normal photoemision using tunable synchrotron radiation in the range of photon energies between 11 eV and 55 eV, and angle-dependent photoemission along the LUX and LKL azimuths using the He resonance lines (=21.2 eV, 40.8 eV). To complement these data, we studied angleresolved secondary electron emission after excitation with electrons and photons. We derive parts of the one-electron energy dispersionE(k) along L, and determine the energies of several bulk critical points (in eV):E(> ₇₊/₈₊)=–2.75±0.10,E(> ₈₊=–0.85±0.10,E(> _7–=16.1±0.5,E(> _6–/> _8–)=20.5±0.5,E(X ₇₊)=–5.0±0.1,E(L ₆₊)=–5.6±0.5,E(L ₆₊/L ₄₊₊₅₊)=–2.65±0.10,E(L ₆₊)=9.0±0.5 eV. Our results are compared to several available band structure calculations.     

Verfolgung der Verbrennungsreaktionen Exothermer Massen auf Basis von Aluminium,Fluoriden und Natriumverbindungen mit Differenzialthermoanalyse

Zusammenfassung Das Verbrennen von Mischungen der exothermen Systeme Al-NaF-NaNO₃ und Al-CaF₂-NaNO₃ wurde durch Röntgenanalyse ergänzte DTA untersucht. Um den Einfluß des durch Dissoziation von NaNO₃ gebildeten Sauerstoffs zu bestimmen wurden auch Mischungen, welche anstatt NaNO₃ NaNO₂ oder Na₂O₂ enthielten, geprüft.Zwei, bei 310° bzw. 850° einsetzende exotherme Reaktionen wurden in den Gemischen vom Typ Al-NaF-NaNO₃ gefunden. Die erste ist der Dissoziation von NaNO₃ zuzuschreiben, die zweite ist der Anwesenheit von Luft zuzuordnen.Beide exothermen Reaktionen wurden im System Al-CaF₂-NaNO₃ in Richtung höherer Temperaturen verschoben. Die Untersuchung der NaNO₂- oder Na₂O₂-haltigen Gemische anstatt NaNO₃ zeigte, daß die Dissoziation von NaNO₃ den zum Verbrennen benötigten Sauerstoff liefert, andererseits würde letztere Reaktion sonst nur in begrenztem Ausmaß stattfinden.

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Combustion of exothermic mixtures belonging to the system Al-NaF-NaNO₃ and Al-CaF₂-NaNO₃ was investigated by DTA and X-ray analysis. In order to determine the influence of the oxygen generated by dissociation of NaNO₃, the mixtures containing NaNO₂ or Na₂O₂ instead of NaNO₃ were also examined.Two exothermic reactions starting at 310° and 850° rsp. were found in the mixtures of the Al-NaF-NaNO₃ type. The first is due to the dissociation of NaNO₃ and the second proceeds independence of the availability of air.Both exothermic reactions were shifted to higher temperatures in the system Al-CaF₂-NaNO₃. Investigation of the mixtures containing NaNO₂ or Na₂O₂ instead of NaNO₃ has proved that the dissociation of NaNO₃ supplies the oxygen required for combustion which should otherwise proceed only in a limited extent.

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Résumé On a étudié, par ATD et par analyse aux rayons X, la combustion des mélanges exothermiques appartenant aux systèmes Al-NaF-NaNO₃ et Al-CaF₂-NaNO₃. Afin de déterminer l'influence de l'oxygène engendré par la dissociation de NaNO₃, on a étudié de même des mélanges contenant NaNO₂ ou Na₂O₂ au lieu de NaNO₃.On a trouvé, dans les mélanges du type Al-NaF-NaNO₃, des réactions exothermiques à partir des temperatures respectives de 310° et 850°. La première est due à la dissociation de NaNO₃ et la seconde dépend de l'air disponible.Dans le système Al-CaF₂-NaNO₃ les deux réactions sont déplacées vers les températures plus élevées. L'examen de mélanges contenant NaNO₂ ou Na₂O₂ au lieu de NaNO₃ à montré que c'est la dissociation de NaNO₃ qui fournit l'oxygène nécessaire pour la combustion. Celleci n'aurait lieu, autrement, que d'une manière limitée.

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, l-NaF-NaNO₃ Al-CaF₂-NaNO₃. , NaNO₃, , NaNO₃, , NaNO₂ Na₂. , Al-NaF-NaNO₃ , 310° 850°. , . Al-CaF₂-NaNO₃ . , NaNO₂ Na₂O₂, , , , , .

     

Sulla esistenza e sulla costruzione effettiva con la «piccola variazione» delle curve algebriche piane con assi di simmetria obliqua e in particolare ortogonale

Riassunto In primo luogo viene giustificata la possibilità per un diametro autoconiugato di una quartica piana di essere asse di simmetria obliqua (in particolare ortogonale) e dopo aver illustrato alcune proprietà sulla simmetria, vengono dati appropriati accorgimenti onde procedere, con la ?piccola variazione?, alla costruzione effettiva delle quartiche piane (dei vari generi) dotate di tutti i possibili assi di simmetria obliqua (in particolare ortogonale), dandone anche, caso per caso, la corrispondente equazione.

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Résumé D'abord on justifie la possibilité, pour les diamètres auto-conjugués, d'être aussi des axes de symmetrie oblique (en particulier orthogonale) pour les quartiques planes et après avoir illustré plusieurs propriétés sur la symmetrie, on donne quelques avisements opportuns pour procéder après à la construction effective, avec la ?petite variation? des quartiques planes (de tous les genres) douées de tous les possibles axes de symmetrie oblique (en particulier, orthogonale), en donnant aussi, chaque cas à part, l'équation correspondante.

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Nota II     

Methylation of 2-phenylamino-1,3,4-thiadiazole. A structure debated

The true identity of the 4-methyl-5-phenylimino-δ²-1,3,4-thiadiazoline (A) has been demonstrated. The reactions, previously reported in the literature to give A have been repeated and the structure of the compounds obtained has been established.     

Costruzione per «piccola variazione» delle curve algebriche sghembe con l'ausilio delle loro secanti multiple

Riassunto Si procede alla costruzione effettiva per ?piccola variazione? delle curve algebriche sghembe dei primi ordini (n≤6) insieme alle loro secanti multiple, riuscendo cosè ad individuare, per ogni ordine e genere, le diverse famiglie della classificazione diHalphen-Nolther e le sottofamiglie caratterizzate dalle loro secanti multiple.

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Résumé On donne la construction effective, par le procédé de ?petite variation?, des courbes algebriques gauches, pour les ordresn≤6, en même temps que de leurs sécantes multiples, et on atteint ainsi, pour tout ordre et pour tout genre, les différentes familles de la classification deHalphen-Noether et les sous-familles qui sont caractérisées par les sécantes multiples.

     

Nuove considerazioni sulla famiglia delle quadriche generalizzate

Si studiano le superficie algebriche d’ordine 2n che toccano il piano all’infinito secondo una conica contatan volte nell’intersezione con detto piano (quadriche generalizzate) e si mettono in rilievo le loro proprietà diametrali.     

Sulla classificazione delle curve algebriche sghembe in base alla determinazione di tutti I multilateri sghembi connessi per ogni ordine e genere

Riassunto In questa Nota viene continuato (per il caso din=7) lo studio dei multilateri sghembi di ordinen e generep dati, conn+p−1 vertici di connessione e che sono casi limite di curve algebriche sghembe irriducibili, studio già iniziato (pern≤6) in un precedente lavoro.

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Résumé Dans cette Note on continue (pour le casn=7) l’étude des multilatères gauches d’ordren et de genrep donnés, ayantn+p−1 sommets de connexion, et qui sont des cas limites de courbes, gauches algébriques irriductibles, étude déjà initiée (pourn≤6) dans un précédent travail.

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(Nota II)

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Lavoro eseguito nell’ambito dell’attività del Gruppo di ricerca n. 26 del Comitato Nazionale per la Matematica del C.N.R. per l’anno accademico 1963–64.     

The nucleon-nucleon potential in the nonrelativistic quark model

The effective nucleon-nucleon potential is presented in the model with two three-quark clusters. The potential is nonlocal and nonadiabatic.The shape of the local adiabatic part strongly depends on the definition of the effective potential and on the choice of the subspace used in the calculation. To get some information about the repulsive core and the weak attractive part, one has also to take into account the nonlocal terms. Then for commonly used quark-quark interactions, a repulsive core is obtained, which is not very sensitive to the choice of the parameters of the quark-quark interaction; beyond the core there is a weak attraction.The trial function is constructed as a mixture of NN, ΔΔ and different coloured baryon-coloured baryon configurations. The trial function is an antisymmetric colour singlet with isospin T = 0, spin S = 1 and orbital angular momentum L = 0.     

Kinetic discrimination of sequence-specific DNA-drug binding measured by surface plasmon resonance imaging and comparison to solution-phase measurements

We demonstrate the use of surface plasmon resonance (SPR) imaging for direct detection of small-molecule binding to surface-bound DNA probes. Using a carefully designed array surface, we quantitatively discriminate between the interactions of a model drug with different immobilized DNA binding sites. Specifically, we measure the association and dissociation intercalation rates of actinomycin-D (ACTD) to and from double-stranded 5'-TGCT-3' and 5'-GGCA-3' binding sites. The rates measured provide mechanistic information about the DNA-ACTD interaction; ACTD initially binds nonspecifically to DNA but exerts its activity by dissociating slowly from strong affinity sites. We observe a slow dissociation time of kd-1 = 3300 +/- 100 s for ACTD bound to the strong affinity site 5'-TGCT-3' and a much faster dissociation time (210 +/- 15 s) for ACTD bound weakly to the site 5'-GGCA-3'. These dissociation rates, which differ by an order of magnitude, determine the binding affinity for each site (8.8 x 10(6) and 1.0 x 10(6) M(-1), respectively). We assess the effect the surface environment has on these biosensor measurements by determining kinetic and thermodynamic constants for the same DNA-ACTD interactions in solution. The surface suppresses binding affinities approximately 4-fold for both binding sites. This suppression suggests a barrier to DNA-drug association; ACTD binding to duplex DNA is approximately 100 times slower on the surface than in solution.