Hydrogen absorption in Zr(AlxB1−x)2 (BFe,Co) laves phase compounds

The hydrogen absorption capacity of the systems Zr(Al_xFe_1?x)₂ and Zr(Al_xCo_1?x)₂ (0? x ?1) was measured at hydrogen pressure of 70 atm and room temperature and at 40 atm and liquid nitrogen temperature. The two systems present very interesting and unexpected results.A dramatic rise in the hydrogen capacity occurs for small x values similar to previous results for the systems Zr(A_xB_1?x)₂ (A  V, Cr, Mn; B  Fe, Co; 0?x?1). The maximum hydrogen content in both systems is achieved for x ≈ $\text{2}\text{12}$ at 40 atm and 80 K. Further increase of the Al content leads, however, to a steep decrease in the hydrogen capacity. This general behaviour is well described by a phenomenological model, recently proposed by us, and thus supporting the importance of short-range neighbouring effects for the hydrogen absorption capacity. The influence of Al on the hydrogen sorption properties in different intermetallic compounds is discussed.     

Subharmonic non-linear acoustic resonances in closed tubes

Summary A closed tube is considered driven at one-half of the fundamental frequency. The interesting fact appears that acoustic theory breaks down in the inviscid case. At a sufficient intensity of a first resonant overtone, the theory of Chester applies.

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Zusammenfassung Betrachtet wird ein geschlossenes Rohr, das bei ber halben Resonanz-frequenz angetrieben wird. Es ergibt sich die bemerkenswerte Tatsache, dass die akustische Theorie im reibungsfreien Fall ihre Gültigkeit verliert. Bei genügend grosser Amplitude eines ersten Obertones ergibt sich die Theorie von Chester.

     

A kinetic study of the reaction between di-h5-cyclopentadienyltungsten dihydride and benzotrichloride

The reaction of di-h⁵-cyclopentadienyltungsten dihydride with benzotrichloride proceeds to produce as the only observed products di-h⁵-cyclopentadienyltungsten dichloride and benzal chloride. The reaction was shown to be first order with respect to Cp₂WH₂. The relative rate of reaction increases substantially with the use of 3,4-dichlorobenzotrichloride in place of benzotrichloride as the oxidizing agent.     

The synthesis of tetrahydroisoquinolines from 1,4-dihydro-3 (2H)-isoquinolones

Experimental procedures are given for the facile synthesis of various types of 1,4-dihydroisoquinolones and their reduction to the corresponding 1,2,3,4-tetrahydroisoquinolines.     

Window region infrared radiation transfer through clouds and the sensitivity of cloud parameters to radiative effects

The effects due to the passage of i.r. radiation through clouds are predominantly due to the window region spectrum (between 8 and 13 μm). An approximation scheme is used to identify those parameters in the cloud model that determine the heating and cooling effects and the sensitivity of these effects to the variations in the parameters. The results show that the anomalously large heating/cooling effects predicted by the exact calculations are actually a consequence of the choice of a homogeneous liquid water content profile and that an adjustment in this profile results in a lessening of these effects. The radiative effects are also found to be dependent on the size distribution in a nontrivial fashion. In particular, it is found that the use of bimodal distributions, a characteristic feature of clouds with entrainment, results in a lowering of the heating and cooling effects, even with a homogeneous vertical profile, to values more realistic than those obtained with monomodal distributions.     

The electrochemical preparation of organo nickel and palladium halides

The electrochemical oxidation of a nickel or palladium anode in the presence of certain organic halides yields the unstable RMX species, which can be stabilised by both mono and bidentate phosphorus(III) ligands. Cyanide compounds of the general formula RNiCN.L₂ can also be synthesised. The advantages of the method are outlined.     

Classes of biorthonormal systems

Summary The (A)-summability and mean-convergence of Fourier series in terms of certain biorthonormal systems have been investigated. The problem of completing a set of polynomials to a biothonormal system has been solved in the case of certain sets of type zero (Sheffer’s classification). The research reported in this document has been sponsored in part by the Air Force Office of Scientific Research of the Air Research and Development Command, United States air Force, through its European Office, under Contract N₀ AF 61 (052)-324.     

The Weiss conjecture on admissibility of observation operators for contraction semigroups

We prove the conjecture of George Weiss for contraction semigroups on Hilbert spaces, giving a characterization of infinite-time admissible observation functionals for a contraction semigroup, namely that such a functionalC is infinite-time admissible if and only if there is anM>0 such that for alls in the open right half-plane. HereA denotes the infinitesimal generator of the semigroup. The result provides a simultaneous generalization of several celebrated results from the theory of Hardy spaces involving Carleson measures and Hankel operators.     

K-Theory for the Banach Algebra of Operators on James''s Quasi-reflexive Banach Spaces

We prove that the K-groups of the Banach algebra of bounded, linear operators on the pth James space , where 1 < p < , are given by and . Moreover, for each Banach space and each non-zero, closed ideal contained in the ideal of inessential operators, we show that and . This enables us to calculate the K-groups of for each Banach space which is a direct sum of finitely many James spaces and -spaces.