Analysis of airborne radon in an ultra-low background experiment

The contribution of 222Rn to the background in a low background experiment with a germanium detector has been estimated. We have also checked the efficacy of a standard radon cleaning system. The cleaning reduces the radon concentration two orders of magnitude with respect to the air in the laboratory. The residual 222Rn represents at most 12.5% of the background in the low energy region, a value low enough for the purpose of our experiment. A detailed study of the radioactive background is presented.     

Decomposition of repetition priming processes in word translation.

Translation in fluent bilinguals requires comprehension of a stimulus word and subsequent production, or retrieval and articulation, of the response word. Four repetition-priming experiments with Spanish–English bilinguals (N = 274) decomposed these processes using selective facilitation to evaluate their unique priming contributions and factorial combination to evaluate the degree of process overlap or dependence. In Experiment 1, symmetric priming between semantic classification and translation tasks indicated that bilinguals do not covertly translate words during semantic classification. In Experiments 2 and 3, semantic classification of words and word-cued picture drawing facilitated word-comprehension processes of translation, and picture naming facilitated word-production processes. These effects were independent, consistent with a sequential model and with the conclusion that neither semantic classification nor word-cued picture drawing elicits covert translation. Experiment 4 showed that 2 tasks involving word-retrieval processes—written word translation and picture naming—had subadditive effects on later translation. Incomplete transfer from written translation to spoken translation indicated that preparation for articulation also benefited from repetition in the less-fluent language. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extraction methods and some physical properties of mesquite (Prosopis chilensis (Mol) Stuntz) seed gum

To evaluate the potential use of mesquite (Prosopis chilensis (Mol) Stuntz) seed gum, the behaviour of the gum was studied using two extraction methods (alkaline and acid), different pH values, two concentrations (0.2 and 0.4% w/v) and different temperatures. The capacity of the gum to stabilise food foams was also evaluated. The alkaline extraction yield (24.9%) was higher than the acid extraction yield (17.7%). Owing molecular to hydrolysis caused by the acid, acid extraction resulted in a lower protein content. Gum from acid extraction had a higher viscosity than that from alkaline extraction at all temperatures investigated (10, 20, 30, 40, 50 and 60 °C). There were no significant differences between the viscosities of mucilage dispersions at the different values of pH studied (3.0, 4.0 and 5.0). The addition of extracted mesquite gum (obtained by either method and at either concentration studied) to egg white foam provided a higher stability and decreased the liquid drainage and collapse of the foam. Copyright © 2004 Society of Chemical Industry     

Heavy metals in organisms of the River Guadalquivir estuary: possible incidence of the Aznalcóllar disaster

On the 25 April 1998, the giant holding pool of the Aznalcóllar mine, owned by the Canadian-Swedish Company Boliden Ltd burst its banks; 5 million cubic meters (6.7 million cubic yards) of sludge poured into the nearby River Guadiamar, which is a tributary of the River Guadalquivir (the main river of the south Iberian Peninsula). Within hours of the accident, approximately 2.5 Hm3 of acidic water with high concentrations of metals, especially Zn, had entered the River Guadalquivir. A biomonitoring program has been carried out to evaluate the incidence of this spill on the fauna of the River Guadalquivir. Six sampling stations within the estuary of were established and six species of molluscs (Crassostrea angulata, Scrobicularia plana), crustaceans (Palameon longirostris, Uca tangeri, Melicertus kerathurus) and fish (Liza ramada) were chosen for analysis. In the Portuguese oyster, Crassostrea angulata, Cd and Cu concentrations were above the maximum allowed by the Spanish legislation for bivalves for human consumption (60 micrograms.g-1 wet wt. for Cu and 1.0 microgram.g-1 wet wt. for Cd). The crustaceans Palaemon longirostris and Uca tangeri, also showed values above the legal limits for Cu (20 micrograms.g-1 wet wt.). An increase of the Zn levels was observed, as Zn concentrations in C. angulata were higher than those reported 30 years ago. The heavy metal concentrations in some of the organisms collected in the River Guadalquivir were higher than in the Bay of Cadiz or the Mediterranean Sea (clean sites), showing that this estuary was subjected to a heavy metal load. One month after the accident, concentrations of Zn were higher in C. angulata and in Palaemon longirostris compared with levels recorded on the 25 April. Nevertheless, some organisms did not show a clear tendency during the sampling period, probably due to the fluctuations of environmental (salinity, temperature) and physiological variables that affect bioaccumulation.     

Complex unitary vectors for the direction of propagation and for the polarization of electromagnetic waves in uniaxial and absorbing dielectric media

The propagation of inhomogeneous and elliptically polarized plane waves in absorbing uniaxial anisotropic media is described using complex unitary vectors to represent the direction of propagation and the direction of polarization. Detailed expressions for electric displacement, electric field, and magnetic field vectors are obtained for the ordinary and extraordinary waves, and their geometry is discussed. According to the complex direction of propagation, three particular cases are studied: the real case (homogeneous wave), the case perpendicular to the optical axis, and the case coplanar with the optic axis. The case of isotropic media is also analyzed.     

Measurement of the colour of white and rosé wines in visual tasting conditions

We have designed a colour measurement method that reproduces the conditions found during visual colour assessment of wines. In particular the illumination, background, wine sampler and the relative positions of sampler, illumination and observer have been controlled. Using this method, the colour of 33 white wines and 33 rosé wines was measured and expressed in terms of the CIELAB colour coordinates. Colour of wine samples was also assessed by expert wine tasters. White wines were classified into three colour categories: Straw-yellow, Yellow-gold and Yellow-green. Rosé wines were classified into four colour categories: Raspberry, Strawberry, Redcurrant and Salmon. The performance of CIELAB colour coordinates to reproduce the observed classification has been established using discriminant analysis. The central region of the wine surface gives the best results having lower measurement errors and higher classification performance. For white wines a*, b* and h _ab are the relevant colour coordinates scoring 84.8% of correctly classified samples. In rosé wines L*, a* and h _ab in the central region correctly classify 100% of the samples. This study demonstrates that colour of white and rosé wines can be measured in the same conditions that are found in the visual colour assessment when precise information on the visual colour appearance of wines is required.     

Comparative study of the pln locus of the quorum-sensing regulated bacteriocin-producing L. plantarum J51 strain

Lactobacillus plantarum J51 strain was isolated from a Rioja red wine and it showed bacteriocin activity against a wide range of lactic acid bacteria of oenological importance. These characteristics conferred L. plantarum J51 a high interest both in wine microbiology and in the study of bacteriocin production. In this work the bacteriocin production regulated under the "quorum-sensing" mechanism is observed and the pln locus of the bacteriocin-producing L. plantarum J51 is fully characterized. A 20,667 bp fragment was completely sequenced (GenBank accession number DQ340868), and showed five operons (plNC8betaalphac, plnLR-like, plnABCD, plnEFI, plnGHSTUVW) and a new region containing a putative operon with three new orfs that could encode a putative two-peptide bacteriocin.