PETROLEUM PROSPECTIVITY OF CRETACEOUS FORMATIONS IN THE GONGOLA BASIN,UPPER BENUE TROUGH,NIGERIA: AN ORGANIC GEOCHEMICAL PERSPECTIVE ON A MIGRATED OIL CONTROVERSY

Organic geochemical studies of Cretaceous formations in the Gongola Basin, northern Nigeria, show TOC values that are generally higher than the minimum (0.5 wt %) required for hydrocarbon generation. Data from Rock‐Eval pyrolysis and biomarker studies indicate the presence of both terrestrial and marine derived Types II and III organic matter, which is immature in the Gombe Formation and of marginal maturity in the Yolde Formation. Immature Type III to IV OM is present in the Pindiga Formation; and Type III OM, with a maturity that corresponds to the conventional onset (or perhaps peak) of oil generation occurs in the Bima Formation. However, Bima Formation samples from the 4710 – 4770 ft (1435.6 – 1453.9 m) depth interval within well Nasara‐1 indicate Type I OM of perhaps lacustrine origin (H31R/H30 ratio generally ≤0.25). Although the Nasara‐1 well was reported to be dry, geochemical parameters (high TOCs, S₁, S₂ and Hls, low Tmax compared to adjacent samples, a bimodal S₂ peak on the Rock‐Eval pyrogram, a dominance of fluorinite macerals), together with generally low H3IR/H30 biomarker ratios within the 4710–4770 ft (1435.6–1453.9 m) interval, suggest the presence of migrated oil, perhaps sourced by lacustrine shales in the Albian Bima Formation located at as‐yet unpenetrated depths. The presence of the migrated oil in the Bima Formation and its possible lacustrine origin suggest that the petroleum system in the Gongola Basin is similar to that of the Termit, Doba and Doseo Basins of the Chad Republic, where economic oil reserves have been encountered.     

Glasses as engineering materials: A review

Glass products have applications in design engineering, and they can solve many special problems. These materials can work in situations in which plastics and metals would fail and need to be part of designer’s repertoire. In some situations, by using these materials, some difficult problems would be solved. This paper contains a number of chapters as follows: a brief about ceramics family, a short history of glass, a brief about physics and the technology of glass fabrication, recently developed glasses with special destinations, testing methods and news about glass parts processing (grinding, waterjet processing, laser cutting, nanoimprint lithography, etc.). The last chapter of this review paper contain some strategic lines of glass usage in industry and estimations about the future of glass development.     

Periodic autoregressive model identification using genetic algorithms

Periodic autoregressive (PAR) models extend the classical autoregressive models by allowing the parameters to vary with seasons. Selecting PAR time‐series models can be computationally expensive, and the results are not always satisfactory. In this article, we propose a new automatic procedure to the model selection problem by using the genetic algorithm. The Bayesian information criterion is used as a tool to identify the order of the PAR model. The success of the proposed procedure is illustrated in a small simulation study, and an application with monthly data is presented.     

Core–shell nanowires: From the ensemble to single-wire characterization

Recent investigations of core–shell nanowires using synchrotron radiation techniques deduced the average structural parameters of heterostructure core–shell nanowires. Here, we report on first results and discuss the problems arising when measuring such complex nanostructures by using nanofocusing X-ray techniques. InAs/InAsP core–shell nanowires exhibit a certain bending, the origin of which is described using finite element simulations assuming a displacement of the core, and a gradient in the chemical composition of the wire’s shell.     

Einheit von Wissenschaft und Kunst im Brückenbau: Hellmut Homberg (1909–1990) – Leben und Wirken (Teil I)

Am 5. September 2009 wäre Hellmut Homberg einhundert Jahre alt geworden. Dies ist Anlass, an sein vor allem den Brückenbau bereicherndes Wirken zu erinnern und ein, wenn auch nicht vollständiges, Werkverzeichnis zu erstellen. Das gilt sowohl für die unter seiner maßgebenden Mitwirkung entworfenen Brücken als auch für seine völlig neuartigen, die statischen Berechnungen in der Praxis erleichternden, streng theoretisch hergeleiteten und eine zutreffende Bemessung der Kreuzwerke und orthotropen Fahrbahnplatten ermöglichenden Tafel‐ und Tabellenwerke. Teil I schildert Homberg s beruflichen Weg und versucht, ein Porträt zu zeichnen; Teil II ist seinen theoretischen Untersuchungen gewidmet, und Teil III geht auf besondere Brücken ein, und. Harmony between science and art in bridge‐building: Hellmut Homberg (1909–90) – life and work (part I). Hellmut Homberg would have been 100 years old on 5 September 2009. This is an opportunity to look back on his work which so enriched the world of bridge‐building in particular, and also a chance to compile a catalogue of his work, albeit incomplete. This applies to the bridges in which he played an influential role in their design and also to his books of mathematical and design tables that enabled the accurate design of beam grids and orthotropic bridge decks. The tables with their rigorous theoretical background were at the time quite new and eased structural calculations in everyday practice. Part I describes Homberg's professional career and attempts to draw a portrait of the man; part II is devoted to his theoretical studies, and part III deals with particular bridges.