Composition,radioactivity, and possible applications of kaolin deposits of Sinai,Egypt

This work discusses the composition, radioactivity, and possible utilization of the kaolin resources in Sinai which are hosted in thick sandstone sequences belonging to the Carboniferous (Wadi Khaboba) and Early Cretaceous (Wadi Iseila and Abansakar) ages. The characterization of kaolin was done by microscopic and SEM examination, supported by XRD and ICP-MS analyses. The studied kaolin resources consist of kaolinite, as the main constituent, associated with subsidiary dickite and halloysite, and minor contribution of smectite and illite. The most dominant non-clay mineral is quartz, besides minor gypsum, dolomite, and hematite. Ferrugination dominates, in most cases, at the upper boundaries of the kaolin lenses, suggesting possible supergene activity. The high Al₂O₃/SiO₂ ratio for the Cretaceous kaolin (0.54, in average) specifies its better grade relative to the Carboniferous kaolin (0.43, in average). The kaolin of the middle part of lens C in Wadi Iseila contains Si/Al molecular ratio of about unity, suggesting high-grade kaolin. The Carboniferous kaolin has enriched the radionuclides: U, Th, and Ra (at disequilibrium state due to leaching of eU relative to Ra) and the REE, relative to that of the Cretaceous age. The Carboniferous kaolin is characterized by a higher contribution of HREE (zircon signature), whereas LREE seems to be more influential for the Early Cretaceous kaolin (monazite signature). In spite of the very high CIA index (93 to 99), none of the analyzed kaolin deposits displays Ce abnormality. The high radioactivity of some Carboniferous kaolin can be a serious impediment for its utilization or its exportation. The kaolin of Sinai does not satisfy the international standards for paperwork industries and refractory manufacturing, but beneficiation may overcome this challenge. However, some lenses have high-grade kaolin with a low percentage of oxides of iron, magnesium, calcium, sodium, and potassium and a low radioactivity, hence nominated for the local refractory industry. The high-grade kaolin of Sinai fulfills the standards required for ceramics manufacturing in the global market. Grade 3 kaolin (< 30%, Al₂O₃) can be used in the manufacturing of white Portland cement and red glaze manufacturing on both local and global markets.     

The Kepler problem: A unifying view

This paper is an attempt to bring unity in the study of the classical Kepler problem by combining, through simple vectorial and quaternionic techniques, its two peculiar aspects: the determination of the constants of the motion and the regularization at the origin.Research supported by the Consiglio Nazionale delle Ricerche of Italy (C.N.R.-G.N.F.M.).     

Dynamics of hourly sea level at Hillarys Boat Harbour,Western Australia: a chaos theory perspective

Water level forecasting using recorded time series can provide a local modelling capability to facilitate local proactive management practices. To this end, hourly sea water level time series are investigated. The records collected at the Hillarys Boat Harbour, Western Australia, are investigated over the period of 2000 and 2002. Two modelling techniques are employed: low-dimensional dynamic model, known as the deterministic chaos theory, and genetic programming, GP. The phase space, which describes the evolution of the behaviour of a nonlinear system in time, was reconstructed using the delay-embedding theorem suggested by Takens. The presence of chaotic signals in the data was identified by the phase space reconstruction and correlation dimension methods, and also the predictability into the future was calculated by the largest Lyapunov exponent to be 437 h or 18 days into the future. The intercomparison of results of the local prediction and GP models shows that for this site-specific dataset, the local prediction model has a slight edge over GP. However, rather than recommending one technique over another, the paper promotes a pluralistic modelling culture, whereby different techniques should be tested to gain a specific insight from each of the models. This would enable a consensus to be drawn from a set of results rather than ignoring the individual insights provided by each model.     

A Synthetic Germanium-Bismuth Glass for the Coarse Mass Calibration of SIMS Instruments

This short technical note describes a simple technique for synthesising an optimised binary glass for performing coarse mass table calibrations of secondary ion mass spectrometers. A Ge-Bi glass doped with five selected trace elements was used to anchor the entire mass table up to m/z ≥ 209 at an accuracy of < 0.5 dalton. Using this material it has been possible to calibrate coarsely the mass table of a Cameca ims 6f instrument in less than five minutes, thereby greatly simplifying the switch from low mass range to high mass range measurements. Although not suitable for the quantification of geological materials, the ease of synthesis and its utility for rapidly performing what is an otherwise time consuming process makes this material a useful tool for SIMS instruments which offer a multiple mass range capability.     

Nitrate source and fate at the catchment scale of the Vibrata River and aquifer (central Italy): an analysis by integrating component approaches and nitrogen isotopes

The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits.     

Predicting financial barriers to formal healthcare utilisation among poor older people under the Livelihood Empowerment Against Poverty Programme in Ghana

GeoJournal - Poor older people surviving under the Livelihood Empowerment Against Poverty (LEAP) programme continue to experience financial difficulties to formal healthcare utilisation despite the...     

The contested and negotiated dominance of Anglophone geography in Greece

In this comment, I discuss the dominance of Anglophone geographical literature in Greece, arguing that it is a recent and still contested phenomenon, to do with broader historical/political circumstances, as well as with the development of geographical studies at university level. In the context of the power-knowledge system, in which Anglophone debates, theory production and spaces of academic communication and exchange dominate, radical academics in Greece are caught in a complex web of contradictions, have to negotiate their/our paths across languages, plural voices, local and international communities.