Habitat islands, genetic diversity, and gene flow in a Patagonian rodent

The effects of terrestrial habitat islands on gene flow and genetic diversity in animal populations have been predicted and discussed in theoretical terms, but empirical data are needed to test these predictions and provide an understanding of the relationships of life-history characteristics to genetics of insular species. We studied saxicolous mice (Phyllotis xanthopygus) in Patagonia to explore genetic structure, phylogeography, and gene flow in a species inhabiting natural habitat islands. Phylogeographic analyses based on mtDNA sequences revealed two haplotype clades, which presumably reflect early Pleistocene factors that temporarily separated the mice into two geographically isolated groups. The Río Chubut, which lies within a glacial drainage basin bisecting northern Patagonia, might have affected gene flow in the species. Although we anticipated isolation by distance and founder phenomena associated with habitat islands, in some habitat patches we found evidence of high local genetic diversity. The amount of divergence in the mitochondrial cytochrome b gene (approximately 3.4%) in animals at a single locality could best be explained through a combination of historical factors and metapopulation source-sink theory. Demographic shifts, dispersal, and episodic recolonization are important in the life history and genetic population structure of P. xanthopygus.     

An improved method for high-curvature detection with applications to automated inspection

Digital curve acquisition with a vision system introduces a large amount of degradation. At the same time ‘corners’ convey important visual information. Unfortunately they are found in the same spectral domain as the quantization noise. Low-pass filtering of the curvature function is compared with more sophisticated methods that keep the angles ‘sharp’. An automated inspection is successfully performed, demonstrating the efficiency of a new method.     

The tightness of retail packaging: A selection of test methods to be used for a wide range of packed products

The tightness of retail packagings and of their closures is of primary importance both for domestic and industrial products. For this reason, a research programme designed to establish proper testing methods for a wide range of ‘packaging + product’ combinations, in order to check their tightness or permeability, was set up. All the available testing methods were reviewed, the most reliable ones selected and their sensitivity determined. More than 200 combinations of ‘packaging + product’ belonging to five families of consumer products were examined and their tightness/permeability problems noted. Finally, specific testing methods were assigned to each combination of ‘packaging + product’. All these examples are currently in use in the packaging laboratory as a guideline for the testing of every kind of packaging.     

Reliability Criteria when Standardizing High Contact Density Connectors

The following paper presents the results of a comparative reliability study conducted on three tpes of high density circular connectors, conforming to NAS 1599, MIL. C. 38 999, and MIL. C. 81 511. After runing numerous relability tests, Souriau has been able to develop a highly successful high density connector.     

Mechanism of retention of hydrocarbons in reservoir rocks. Role of polar compounds and effect of additives

Evidence is given for the involvement of hydrophobic interactions in the retention of hydrocarbons in oil fields. A prerequisite is that the surface of the reservoir rock has to be hydrophobic. This was obtained through adsorption of lipophilic polar compounds. The isotherms for the adsorption of dodecylamine hydrochloride and N-hexadecylpyridine hydrochloride were plotted. The treated quartz could take up large amounts of toluene. The relationships between some features of the isotherms and the retention phenomenon have been analysed. The effect of water-structuring additives (e.g. LiF, CaCl₂, NaF and guanidine hydrochloride) on the recovery of hydrocarbons was investigated by means of static and dynamic methods.     

Rheological properties of poly(acrylonitrile‐co‐methyl acrylate)/clay nanocomposites prepared via emulsion polymerization

Poly(acrylonitrile‐co‐methyl acrylate)/clay nanocomposites were prepared by free radical polymerization in emulsion using 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid (AMPS) as a compatibilizer. The resultant nanocomposites were of partially exfoliated morphology despite the variations in clay content among the nanocomposites, as confirmed by transmission electron microscopy and small‐angle X‐ray scattering analysis. Rheological studies of these materials were carried out using parallel plate geometry. The storage modulus increased monotonically with increasing clay content throughout the frequency range studied. However, the neat copolymer, poly(acrylonitrile‐co‐methyl acrylate) and its nanocomposites, exhibited long relaxation behavior as the storage modulus (G′) was greater than the loss modulus (G″) throughout the angular frequency range studied. The complex viscosity of the nanocomposites increased with increasing clay content and they exhibited shear‐thinning behavior. Despite the enhanced rheological properties observed, the copolymer and its nanocomposites underwent structural changes during oscillatory measurements due to cyclization reactions. POLYM. COMPOS., 32:59–66, 2011. © 2010 Society of Plastics Engineers     

Preparation of Polystyrene/Clay Nanocomposites by Free‐Radical Polymerization in Dispersion

Fully exfoliated PS/clay nanocomposites were prepared via FRP in dispersion. Na‐MMT clay was pre‐modified using MPTMS before being used in a dispersion polymerization process. The objective of this study was to determine the impact of the clay concentrations on the monomer conversion, the polymer molecular weight, and the morphology and thermal stability of the nanocomposites prepared via dispersion polymerization. DLS and SEM revealed that the particle size decreased and became more uniformly distributed with increasing clay loading. XRD and TEM revealed that nanocomposites at low clay loading yielded exfoliated structures, while intercalated structures were obtained at higher clay loading.

     

Rapid Determination of Free Fatty Acid in Extra Virgin Olive Oil by Raman Spectroscopy and Multivariate Analysis

We introduce a visible Raman spectroscopic method for determining the free fatty acid (FFA) content of extra virgin olive oil with the aid of multivariate analysis. Oleic acid was used to increase the FFA content in extra virgin olive oil up to 0.80% in order to extend the calibration span. For calibration purposes, titration was carried out to determine the concentration of FFA for the investigated oil samples. As calibration model for the FFA content (FFA%), a partial least squares (PLS) regression was applied. The accuracy of the Raman calibration model was estimated using the root mean square error (RMSE) of calibration and validation and the correlation coefficient (R ²) between actual and predicted values. The calibration curve of actual FFA% obtained by titration versus predicted values based on Raman spectra was established for different spectral regions. The spectral window (945–1600 cm⁻¹), which includes carotenoid bands, was found to be a useful fingerprint region being statistically significant for the prediction of the FFA%. High R ² and small RMSE values for calibration and validation could be obtained, respectively.