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Abstract: The 119Sn Mössbauer spectra have been measured for the intermediate valent CeSn3 (stoichiometric) and CeSn3.1 (slightly non-stoichiometric) high-quality single crystals in the temperature range from 300 to 30K with an aim to look into the local surrounding of the Sn site and its valence state in these crystals. The spectra clearly indicate a para-magnetic ground state throughout the temperature range. Two different doublets with a quadrupole interaction that we associate with two different paramagnetic S1 and S2 sites, result from our first attempt to fit the experimental spectra, the ratio between these sites S1/S2 being around 3/1. The magnitudes of isomer shift reveal a 2+ valence state for the Sn, that does not show any change for either the S1 or the S2 sites, in the whole investigated temperature range. The different values of quadrupole splitting ΔE Q for S1 and S2 again confirm that the Sn atoms have different atomic coordinations. [Copyright &y& Elsevier]

Quality assurance in engineering education is a multifaceted problem further augmented by the stakeholders of engineering education. Students, parents and employers are rightfully questioning the quality of the curriculum, the instructional delivery, the learning environment, accessibility to learning technologies and equipment, employability as well as the possibilities of lifelong learning and the improvement of knowledge (Karapetrovic 2002). The purpose of the study is, therefore, to identify the parameters that influence the quality of an engineering education system and develop an integrated model of hierarchical structuring and a concept map for pre-identified concept elements through a process of iterative-interactive consensus-driven methodology, as advocated by second-generation system design paradigm for evolving knowledge scenario of concepts related to quality engineering education. [ABSTRACT FROM AUTHOR]

Abstract: X-ray absorption measurements have been made on CuL3 and OK edges for two transition metal substituted Hg based oxycarbonates Hg0.5Mo0.5Sr4Cu2(CO3)O6+ δ and Hg0.4Cr0.6Sr4Cu2(CO3)O6+ δ . Despite a much lower T c (37K) the Cr sample has a much higher diamagnetic fraction than the Mo sample (T c∼74K). CuL3 and OK edge spectra clearly indicate the presence of substantial number of doping holes in both the samples characteristic of their superconducting properties. But interestingly, the density of holes (DOH) are almost the same for the two samples. If the DOH correlated with the T c solely, one would expect it be nearly double in Mo sample than the Cr one. Thus the present study presents a strong evidence for the dependence of DOH upon diamagnetic fraction over and above its dependence upon their transition temperature in the cuprate perovskites. Also the results of resistivity and susceptibility studies made earlier on these samples have been mentioned briefly. [Copyright &y& Elsevier]

Cu L3 and O K edge polarised X-ray absorption spectroscopy has been employed to study a three-dimensional oxygen deficient perovskite single crystal of La8-xSrxCu8O20-δ (8820) (x=1.56) for E//a, E//b and E//a^45 polarizations. A careful analysis of the data shows an unmistakable presence of the itinerant eg(x2–y2) holes in it. The density of itinerant holes increases slightly as we move from E//a to the E//b orientation. This behaviour seems to be similar to the charge aggregation taking place along b-direction in an under-doped YBCO crystal in the normal state but it is rather strange as this system does not become superconducting on further cooling. This intriguing behaviour warrants further investigation. [Copyright &y& Elsevier]