Quasar red shifts

The results of techniques developed in earlier papers are used in a discussion of the quasar red shifts. An expression with the form of a kinetic energy arises in relation to the probability distribution of red shifts. Agreement with the Hoyle & Burbridge (1966) red shift data at the time of writing is statistically significant, the correlation coefficient being 0·82.     

ESCA study of fractional monolayer quantities of chemisorbed gases on tungsten

X-ray photoelectron spectroscopy (ESCA) has been used in a study of CO and O₂ chemisorbed on a polycrystalline tungsten sample. Working under ultra-high vacuum conditions, the surface was cleaned and then covered with known monolayer and fractional monolayer quantities of adsorbed CO and O₂. The O(ls) and C(ls) spectral features were detected, and the influence of an adsorbed layer on the tungsten spectral features was determined. A chemical shift of 3.4 eV in the O(ls) line from chemisorbed CO is related to the different modes of bonding of CO to tungsten. A model calculation of the photoelectron yields expected from an adsorbed monolayer is in good agreement with the experimental results.     

Integration of Markov and Linear Programming Models to Assess the Farmgate and National Consequences of Adopting New Bovine Reproductive Technologies in the United Kingdom Agriculture

Despite many advances in biotechnology being futuristic, in some industries such technological improvements are now becoming generally available for absorption into commercial practice. The new reproductive technologies for bovine animals are such an example. For a regulated industry like agriculture, an ex ante evaluation of the impact of their adoption is the concern of policy makers. This paper describes a modelling strategy devised to assess these impacts, using a sequence of stochastic, financial and linear programming models. A set of individual farm type models were developed and later extended to a national model to simulate the interactions that occur between dairy and beef enterprises and the competition between them for resources on individual farms. Restraints reflecting national policies such as quotas on milk production and industry support through subsidies are built into the model to explore several scenarios. These models are used to assess the impact of new technologies on dairy and beef production nationally and for regions which have been identified by the Ministry of Agriculture, Fisheries and Food.     

Evidence for the conformation of H2O adsorbed on Ru(001)

The electron stimulated desorption ion angular distributions (ESDIAD) method has been used to study the adsorption of H₂O by Ru(001). The results indicate that chemisorbed, undissociated H₂O is bonded to Ru via the oxygen atom, and that interactions between neighboring molecules occur as coverage increases. The utility of ESDIAD for structure determination in the absence of long range order is demonstrated.     

Comparison of packed and capillary columns for practical SFC separations

Summary A newly developed polysiloxane-type packing material shows promise for use in SFC. Relatively polar compounds were eluted from a microbore column with good peakshape using a mobile phase consisting of CO₂ modified with formic acid and water. The latter combination is an effective modifier suitable for use with pressure programming and FID detection.

---

Vergleich von gepackten und Capillar-Säulen für praktische SFC-Trennungen

     

Die Struktur der Grenzfl?che Kiesels?ure/Elektrolyt

Ohne Zusammenfassung     

The elastic properties of some phosphate/vanadate glasses

The elastic constants of 7 phosphate/vanadate glasses, containing TiO₂, Na₂O and a range of concentrations of CuO, have been measured from 4.2 to 300 K. The pressure variation of the elastic constants has also been measured and has been used to calculate the low temperature value of the Grüneisen parameter γ_O for these glasses. Analysis of the results and other data has been used to show how TiO₂, Na₂O and CuO may be incorporated in the structure of these P₂O₅/V₂O₅ glasses.     

A “high-pressure” electron spectrometer for surface studies

A photoelectron spectrometer which permits the study of solids in the presence of gas at up to 1 Torr pressure has been developed and the main factors considered in its design and construction are described. The inelastic mean free path of 890 eV kinetic energy electrons through argon at 1 Torr has been measured and shown to be 4.5 ± 1 mm. The X-ray induced valence band spectrum of liquid mercury is also reported. It is in good agreement with calculation (S.C. Keeton and T.L. Loucks, Phys. Rev. 152 (1966) 548), but shows some differences from that of condensed mercury monolayers at 163 K (S. Svensson et al., J. Electron Spectrosc. 9 (1976) 51).     

The influence of N-substitution on the reductive elimination behaviour of hydrocarbyl-palladium-carbene complexes--a DFT study

The reductive elimination of 2-hydrocarbyl-imidazolium salts from hydrocarbyl-palladium complexes bearing N-heterocyclic carbene (NHC) ligands represents an important deactivation route for catalysts of this type. We have explored the influence that carbene N-substituents have on both the activation energy and the overall thermodynamics of the reductive elimination reaction using density functional theory (DFT). Given the proximity of the N-substituent to the three-centred transition structure, steric bulk has little influence on the activation barrier and it is electronic factors that dominate the barriers' magnitude. Increased electron donation from the departing NHC ligand acts to stabilise the associated complex against reductive elimination, with stability following the trend: Cl < H < Ph < Me < Cy < iPr < neopentyl < tBu. The intimate involvement of the carbene p pi-orbital in determining the barrier to reductive elimination means N-substituents that are capable of removing pi-density (e.g. phenyl) act to promote a more facile reductive elimination.