Hippocampal morphology and cognitive functions in community-dwelling older people:the Lothian Birth Cohort 1936

Structural measures of the hippocampus have been linked to a variety of memory processes and also to broader cognitive abilities. Gross volumetry has been widely used, yet the hippocampus has a complex formation, comprising distinct subfields which may be differentially sensitive to the deleterious effects of age, and to different aspects of cognitive performance. However, a comprehensive analysis of multidomain cognitive associations with hippocampal deformations among a large group of cognitively normal older adults is currently lacking. In 654 participants of the Lothian Birth Cohort 1936 (mean age = 72.5, SD = 0.71 years), we examined associations between the morphology of the hippocampus and a variety of memory tests (spatial span, letter-number sequencing, verbal recall, and digit backwards), as well as broader cognitive domains (latent measures of speed, fluid intelligence, and memory). Following correction for age, sex, and vascular risk factors, analysis of memory subtests revealed that only right hippocampal associations in relation to spatial memory survived type 1 error correction in subiculum and in CA1 at the head (β = 0.201, p = 5.843 × 10(−4), outward), and in the ventral tail section of CA1 (β = −0.272, p = 1.347 × 10(−5), inward). With respect to latent measures of cognitive domains, only deformations associated with processing speed survived type 1 error correction in bilateral subiculum (β(absolute) ≤ 0.247, p < 1.369 × 10(−4), outward), bilaterally in the ventral tail section of CA1 (β(absolute) ≤ 0.242, p < 3.451 × 10(−6), inward), and a cluster at the left anterior-to-dorsal region of the head (β = 0.199, p = 5.220 × 10(−6), outward). Overall, our results indicate that a complex pattern of both inward and outward hippocampal deformations are associated with better processing speed and spatial memory in older age, suggesting that complex shape-based hippocampal analyses may provide valuable information beyond gross volumetry

Study of blends based on recycled polyethylene wastes: Part II. Thermal behaviour and degree of molecular mixing

6 pags., 3 figs., 2 tabs.A calorimetric study of binary blends based on recycled, low and high density polyethylene, wastes is presented. The physical properties of these blends were reported previously [1]. A comparison between the first and second differential scanning calorimetry (DSC) traces of blended samples reveals the presence of an intermediate endothermic peak which can be associated to the melting of crystals from mixed molecular species of the single components. Further thermal treatments after the second DSC run at temperatures just below and above the intermediate peak for two compositions (φB = 10 and 30% of high density component) highlight the dependence of the various crystal populations upon annealing. A quantitative analysis of a series of consecutive thermograms for each sample has allowed us an estimation of the relative amount of material associated to the three main endothermic peaks. © 1996 Chapman & Hall.L.M. and A.V. acknowledge the tenure of a grant within the TEMPUS programme (JEP4773 and JEP6154). Thanks are due to DGICYT (Grant PB94- 0049), Spain, for the generous support of this work

Study of blends based on recycled polyethylene wastes - Part I Variation of mechanical properties with composition

6 pags., 6 figs.Data covering the physical properties of molten and solid samples of two binary blends of recycled polyethylene wastes, in a wide range of compositions, are reported. While some properties (density, fusion enthalpy) show a linear behaviour with composition other properties (microhardness, yield stress) show a deviation from linearity. Deviation of microhardness additivity of the single components has been interpreted, after analysis of the DSC thermograms, as being due to segregation and recombination of molecular species from both components during crystallization. It is also suggested that the presence of a high oxidation in one low-density polyethylene component, detected by infrared spectroscopy, influences the very low values observed for the melt flow index and melt elongation at break. © 1994 Chapman & Hall

Physical aging in poly(ethylene naphthalene‐2,6‐dicarboxylate) in relation to sorbed water, enthalpic relaxation, and mechanical properties

9 pags., 11 figs.Amorphous poly(ethylene naphthalene‐2,6‐dicarboxylate) (PEN) films (∼ 220 μm thick), stored in ambient atmosphere for different periods of time and after annealing at different temperatures below T = 123°C, for different times, have been investigated by infrared spectroscopy (FTIR), microhardness, and differential scanning calorimetry (DSC). FTIR spectroscopy and weight measurements reveal the presence of water which is easily removed by annealing of the films. Films again recover their initial weight and absorption bands after 1‐2 days storage in ambient atmosphere. Samples annealed at different temperatures T for different times t show an increasing microhardness for relatively short times of t. The microhardness passes through a maximum at an annealing time depending on T, and it decreases toward values somewhat larger than the initial ones. The changes observed in the microhardness and in the values of the excess enthalpy with storage time of the samples at room temperature depend on the physical aging as well as on the content of water of PEN films. © 1995 John Wiley & Sons, Inc. Copyright © 1995 John Wiley & Sons, Inc

Properties of arylpolyesters with reference to water content

10 pags., 5 figs.The 4000–2000 cm infrared spectral region from transmission FTIR spectra of films (≈ 220 μm thick) of amorphous poly (ethylene terephthalate) (PET) and poly(ethylene 2, 6‐naphthalenedicarboxylate) (PEN) was analyzed. In addition to the strong bands for the stretching vibration modes of H‐C bonds, the ester‐overtone band at about 3430 cm and a doublet (3630, 3550 cm) band, related to absorbed water, appear. The spectra for these materials show significant differences in absorptivity and frequency for the ester overtone band. Real time water sorption/desorption in these films was investigated simultaneously by FTIR spectroscopy and by measurement of weight changes. A linear correlation between the integrated absorbance of the water bands and the relative weight variation of the films was found for these two polymers. Results show that the infrared absorptivity of these bands is identical in both materials and that water molecules are weakly bound to ester groups throughout the films. However, it turns out that the water content is higher in the case of PEN which has a larger specific volume. Copyright © 1995 Hüthig & Wepf Verla