Archaeo-metallurgical studies of tuyeres and smelting slags found at Tharros (north-western Sardinia, Italy)

A large number of pyrometallurgical materials such as tuyeres, slags and refractory tools likely associated with metal extraction processes have been found at Tharros (north-western Sardinia, Italy) during archaeological excavations stratigraphically related to the Phoenician–Punic period (VI–III centuries BC). Micro-chemical, micro-structural and mineralogical studies have been carried out by means of the combined use of X-ray diffraction (XRD), selected-area X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray analysis (EDS) in order to identify pyrometallurgical processes and main relevant technological parameters. The results reveal that tuyeres, slags and refractory tools can be associated with an iron ore smelting process to extract the metal by slagging the unwanted by-products. Moreover, temperature and duration of the smelting process have been estimated through mineralogical studies and by a comparative analysis between the micro-chemical and structural features of thermally treated refractory materials and tuyeres. The results disclose the high level of technological competence of the ancient metallurgists able to carry out complex high-temperature processes to extract iron from ores by separating the metal from unwanted siliceous species.     

The longitudinal asymmetry of the interplanetary perturbation producing Forbush decreases

Summary It is well known that type-IV solar flares occurring between 0° and 40° East of the central meridian can produce the largest Forbush decreases observed at the Earth,i.e. inside the Forbush decrease modulated region the maximum cosmic-ray modulation is observed in the West (∼20° W) of the flare’s meridian plane. A flare-produced perturbation asymmetric in longitude is required in order to explain this asymmetry. The analysis of the two-step Forbush decreases shows that the first step of the decrease is symmetric with respect to the flare’s meridian plane and it is due to the shock wave which is observed ahead of the interplanetary perturbation; on the contrary the second step is strongly asymmetric, the maximum amplitude being observed at ∼30° W of the flare’s meridian plane, and it seems to be due to the magnetic perturbation following the shock; this perturbation is an irregular and compressed magnetic field, the maximum magnetic-field magnitude is found to be placed West of the flare’s meridian plane. The total Forbush decrease amplitude is correlated (correlation coefficient 0.96) with a perturbation parameter which accounts for the ?strength? of the shock and of the following magnetic perturbation. The first step of the decrease is correlated (correlation coefficient 0.88) with the shock ?strength?.

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Riassunto è ben noto che i brillamenti solari accompagnati da radioemissione di tipo IV nell’intervallo 0°–40° est possono produrre le maggiori diminuzioni di Forbush osservate alla terra; cioè, dentro la regione interplanetaria interessata dalla dimizuzione di Forbush la massima modulazione dei raggi cosmici è osservata a circa 20° ovest dal piano meridiano del brillamento solare. Per spiegare questa asimmetria si richiede l’esistenza di una perturbazione interplanetaria generata da brillamento che sia di tipo asimmetrico. L’analisi delle diminuzioni di Forbush ?a due gradini? mostra che la prima diminuzione ha una dipendenza simmetrica rispetto al piano meridiano del brillamento ed è dovuta all’onda d’urto che è osservata all’inizio della perturbazione stessa. La seconda diminuzione, al contrario, è fortemente asimmetrica poiché la massima ampiezza è osservata a circa 30° ovest del piano meridiano del brillamento; essa sembra essere dovuta alla perturbazione magnetica (caratterizzata dal campo magnetico compresso e irregolare) che segue l’onda d’urto; la massima ampiezza del campo magnetico si trova a ovest del piano meridiano del brillamento. L’ampiezza totale delle diminuzioni di Forbush è correlata (coefficiente di correlazione 0.96) con un parametro empirico della perturbazione che tiene conto dell’importanza dell’onda d’urto e della perturbazione magnetica che segue, mentre il primo ?gradino? della diminuzione è correlato (coefficiente di correlazione 0.88) soltanto con il parametro dell’onda d’urto.

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Ррзюме Хорошо известно, что солнечные вспышки типа IV, возникающие в интервале между 0° и 40° к востоку от центрального меридиана, могут порождать большие убывания форбуша, наблюдаемые на Земле, т.е. внутри модулированной области убывания форбуша наблюдается максимальная модуляция космических лучей около 20° к западу от меридианной плоскости солнечной вспышки. Для объяснения этой асимметрии требуется существование межпланетного возмущения, образованного вспышкой, которое является асимметричным по долготе. Анализ двух-ступенчатых убываний форбуша показывает, что первая ступень убывания является симметричной относительно меридианной плоскости вспышки и обусловлена ударной волной, которая наблюдается перед межпланетным возмущением; напротив, вторая ступень является сильно асимметричной, максимум интенсивности наблюдается около 30° к западу от меридианной плоскости вспымки, и, по-видимому, является результатом магнитного возмущения после ударной волны; это возмущение является иррегулярным и вызывает сжатие магнитного поля. Максимум амплитуды магнитного поля расположен к западу от меридианной плоскости вспышки. Полная амплитуда убывания форбуша коррелирует (коэффициент корреляции 0.96) с параметром возмущения, который характеризует ?интенсивность? ударной волны и последующее возмущение магнитного поля. Первая ступень убывания Форбуша коррелирует (коэффициент корреляции 0.88) только с ?интенсивностью? ударной волны.

     

Experimental progress in the nonlinear behavior of semiconductors

During the past five years spontaneous oscillations and chaotic behavior have been observed in the electronic transport of many semiconductors. Whereas the temperature range of some experiments extends up to room temperature, the majority of the measurements have been performed at liquid helium temperatures. We summarize these experimental developments and discuss their impact on the field of nonlinear dynamics which is rapidly progressing at present.     

Molecular imprinting polymerization by Fenton reaction

The aim of this study is the preparation of molecularly imprinted polymers by employing a redox pair as initiator system. Bulk molecularly imprinted polymers were synthesized by using Fenton reagents as initiator system. Theophylline, methacrylic acid, and ethylene glycol dimethacrylate were employed as model template, functional monomer, and crosslinking agent, respectively. Conventional imprinted polymers were also prepared by using 2,2′-azoisobutyronitrile in order to evaluate the efficiency of the proposed initiator system. Redox molecularly imprinted polymers and conventional molecularly imprinted polymers were characterized by water uptake measurement, while the imprinting effect of synthesized polymers were evaluated by performing binding experiments in organic (acetonitrile) and in water (buffered water solution at pH = 7.4) media.     

On complemented copies of c 0 and ℓ ∞

We furnish examples of pairs of Banach spaces X, Y so that none of c ₀ and l _∞ live inside X ^? and Y, but they embed complementably into the space DP(X,Y) of the Dunford–Pettis operators from X into Y.     

Phase transitions in experimental systems

Scaling functions of the support and of the measure have been used to characterize the scaling behavior of a dynamical system. While scaling functions for the scaling of the measure, ƒ(), have been calculated for a number of experimental systems, examples of scaling functions φ(λ) for the scaling of the support are difficult to obtain. In this contribution, we report on a phase-transition-like effect of an experimental p-doped germanium semiconductor sample. It is found that the results obtained from the dynamical scaling function agree with those obtained by Horita et al. from model maps, indicating that scaling functions for the scaling of the support are a powerful method of characterizing experimental dynamical systems.     

Nonlinear gravitational waves,their polarization,and realistic sources

We describe exact solutions of the Einstein field equations invariant under a non-Abelian two-dimensional Lie algebra of Killing fields. A subclass of these gravitational fields have a wavelike character. We show that they have spin 1. We also discuss some indirect observational effects. In particular, we show that vector cosmological perturbations can no longer be negligible in the presence of topological defects, which can be verified by examining the anisotropies of the cosmic microwave background. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 152, No. 2, pp. 225–240, August, 2007.     

Students as toolmakers: refining the results in the accuracy and precision of a trigonometric activity

Smartphones used as tools provide opportunities for the teaching of the concepts of accuracy and precision and the mathematical concept of arctan. The accuracy and precision of a trigonometric experiment using entirely mechanical tools is compared to one using electronic tools, such as a smartphone clinometer application and a laser pointer. This research has demonstrated how two classroom activities based on tool-making can enhance student measurement and application of accuracy and precision considerations through a trigonometric activity investigating arctan.     

Orthogonal chain length control in calix[5]arene-based AB-type supramolecular polymers

New AB-type supramolecular polymers have been prepared by acid-promoted self-assembly of an aminododecyloxy-calix[5]arene monomer precursor. The number-average degree of polymerization has been found to be dependent on the concentration of the salt monomer and on the nature of the counterion (i.e., chloride, picrate or hexafluorophosphate).Chain-length regulation experiments have been carried out, employing orthogonal chain stoppers capable of selectively interacting with a given moiety of the AB-type monomer/polymer. Competitive calix[5]arene ‘caps’ and n-butylammonium ion ‘plugs’ have been used to control the extent of self-assembly of the polymer, in turn interacting with the ammoniumdodecyloxy or with the cavity end-groups of the supramolecular calixarene assembly. These experiments, conveniently carried out at a 10 mM concentration, can be easily followed by ¹H NMR spectroscopy.