Morphology of polyethylene ski base materials

Abstract

We used high-resolution Raman spectroscopy and differential scanning calorimetry for a comprehensive analysis of carbon black-filled polyethylene ski base grades at processing stages from the raw material to the structured ski base. Based on Raman mapping, we assessed the applicability of an advanced evaluation procedure for amorphous, disordered, and crystalline phase fractions of polyethylene for polyethylene extrusion and sinter grades. For sinter grades, a sufficient segregation between carbon black and polyethylene was confirmed, allowing for a comprehensive Raman spectroscopic morphological analysis. Significant morphological changes in polyethylene due to processing from the raw material to the semi-finished film and to the structured ski base were identified. Throughout the processing chain, we observed a decrease in crystallinity and an increase in the amorphous phase fraction. Although the raw material and the sintered semi-finished film exhibited a different but uniform polyethylene morphology, the morphological changes due to structuring of the ski base are limited to the top surface layer. The highest amorphous phase fractions were detected in the surface of the structured ski bases.     

When Glass and Metal Corrode Together,V: Sodium Copper Formate

A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu₄Na₄O(HCOO)₈(OH)₂·4H₂O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses.     

Electroencephalographic Coherence and Learning: Distinct Patterns of Change During Word Learning and Figure Learning Tasks

One likely mechanism in learning new skills is change in synchronous connections between distributed neural networks, which can be measured by coherence analysis of electroencephalographic patterns. This study examined coherence changes during the learning of two tasks, a word association task and a figure association task. Although learning curves were similar for both tasks, distinct patterns of coherence change were observed. Coherence tended to increase as learning progressed in the figure association task. In contrast, coherence tended to decrease in the word association task, especially within hemisphere. Word learning was coupled with negative intrahemispheric and positive interhemispheric performance–coherence relations in the gamma frequency. Unique to the figure learning task was an increase in the number of positive coherence–performance relations in both delta and theta frequencies across blocks. Results are discussed in light of ongoing efforts to identify the mechanisms that coordinate distributed brain activities during the process of learning. Further research is needed to define patterns of coherence change for different tasks, goals, and brain regions.     

International Communications

Mark J. Hopkin's Mass Media in the Soviet Union (New York: Pogasus, $8.95)

Richard E. Wood's Shortwave Voices of the Torld (Gilfor Assoc., P.O. Box 239, Park Ridge, N.J. 07656, $6.35 hardback, $3.95 paperback

Heinz-Dietrich Fischer and John C. Morrill, International Communications: Media, Channels, Functions (Hasting, $12.95)     

‘A Glance from God’: Zadie Smith's On Beauty and Zora Neale Hurston1

Zadie Smith's most recent novel, On Beauty (2005 Smith, Z. 2005. On Beauty, London and New York: Penguin.  [Google Scholar]), declares its connection to E. M. Forster's Howards End (1910 Forster, E. M. 1910. Howards End, London: Edward Arnold.  [Google Scholar]) with its first line, while the novel's title comes from Elaine Scarry's On Beauty and Being Just (1999 Scarry, E. 1999. On Beauty and Being Just, Princeton, NJ: Princeton University Press.  [Google Scholar]). At least as important for understanding Smith's central vision are the novel's allusions to Zora Neale Hurston's Their Eyes Were Watching God (1937 Hurston, Z. N. 1987. Their Eyes Were Watching God, London: Virago Modern Classics.  [Google Scholar]) and Tell My Horse: Voodoo and Life in Haiti and Jamaica (1938 Hurston, Z. N. 1990. Tell My Horse: Voodoo and Life in Haiti and Jamaica, New York: Perennial Library.  [Google Scholar]).