The objectives of this study were to (i) assess trace metal concentrations in Hydrilla verticillata and sediment from an estuarine creek in Alabama (USA), where high metal levels in biota were previously reported, and (ii) investigate the relationship between metal concentrations in H. verticillata and the sediment compartment. Our results indicate that sediment and H. verticillata exhibit moderate metal concentrations in the study area. We found that levels in plant tissues can be up to five times higher than in the sediment (e.g., Cd), suggesting that H. verticillata can take up and store several trace metals (Cd, Hg, Ni, and Zn) from this compartment. Together with studies focused on the uptake and accumulation of trace metals from the surrounding water, laboratory- and field-based studies are needed to better evaluate this plant's ability to acquire metals from the sediment that constitutes a contaminant sink in human-impacted coastal regions.

The overarching goal of this in situ study was to investigate the integrated impact(s) that metal/metalloid contamination might have on the overall health and performance of the ecologically important aquatic macrophyte, Vallisneria neotropicalis. Morphological (i.e., shoot growth-based endpoints) and photo-physiological (i.e., photosynthetic activity measured as chlorophyll a fluorescence and oxygen exchange) variables, along with aboveground tissue metal/metalloid concentrations, were measured in natural populations of V. neotropicalis that differed with respect to their anthropogenic pressure. With the exception of an overall negative effect on growth, our results suggest that there were no detrimental effects of low/moderate contamination of V. neotropicalis by trace elements (i.e., arsenic As and mercury Hg; 1.04-2.77 μg g(-1) dry wt. and 3.76-15.18 ng g(-1) dry wt., respectively) on the photosynthetic physiological performance of this species. V. neotropicalis appears to tolerate low/moderate levels of trace element contamination with little impact on plant health and performance.

Arsenic (As) and mercury (Hg) are among the most toxic metals/metalloids. The overall goal of this study was to investigate the bioaccumulation of these trace elements in Vallisneria neotropicalis, a key trophic species in aquatic environments. For this purpose, As and Hg concentrations were determined in sediments and natural populations of V. neotropicalis in sub-estuaries of Mobile Bay (Alabama, USA), differing with respect to past and present anthropogenic impact. Analyses indicate that the Fish River is the most contaminated among the sub-estuaries investigated; levels of As found in Fish River sediments fall within a range that could potentially cause adverse effects in biota. Sediment As concentrations were only moderately correlated with those in V. neotropicalis; no correlation was found between sediment and plant Hg levels. However, several parameters could have masked such potential relationships (e.g., differences in sediment characteristics and “biological dilution” phenomena). Results presented herein highlight the numerous parameters that can influence metal/metalloids accumulation in aquatic plants as well as species-specific responses to trace element contamination. Finally, this study underscores the need for further investigation into contaminant bioaccumulation in ecologically and economically important coastal environments.

Al doped ZnO (ZAO) films are widely used as transparent contacts of thin film solar cells. Having a reliable and reproducible laser cutting technology is critical for the thin film solar cell device manufacturing. Cutting experiments were carried out in wide range of parameters (1-25cm/s speed, 1-10kHz pulse frequency and 200-5800mW power) but the pulse energy was kept in a narrow range. Optical microscopy of the cuts revealed that there is a critical power for the full ablation of the layer. A parameter range for optimal cutting as a function of the layer thickness is established. Ellipsometry measurements were evaluated by a Cauchy model using a double-layer optical model and resulting in a reliable thickness measurement. Criteria for the transparent conductive character of the layer are also established. These results offer a feasible in-line technique for setting proper cutting parameters of the TCO layer.

In 2002 the Hungarian Paks NPP started a large-scale reconstruction project to upgrade its core monitoring system called VVER On-Line Analysis (VERONA). The main reason for the reconstruction decision was the planned reactor thermal power increase from 1375 MW to 1485 MW (108%), in order to achieve 500 MW electric power output. Considering safety margins and operation limits the basic approach was to keep all previously valid limits at 108%, as well. However, increased core power and a new type of fuel required a more accurate and more frequent core analysis; therefore modernization of the VERONA system was necessary and unavoidable. At this moment Unit 3 and Unit 4 are served by the new system. The reconstruction project is planned to be fully completed in 2008, when all Paks units will have a modernized core analysis system, providing state-of-the art services and operator support.The paper first presents a brief overview of the reconstruction process, and then main design principles and functions of the new VERONA system are outlined. Details of the new system architecture, hardware devices and software tools are also given, and then elements of the new human-machine interface are described and illustrated. A special emphasis is devoted to the new core analysis software with a detailed description of the validation methods and results. The process of reaching 108% power at Unit 4 is discussed; core behavior is illustrated by real data taken during the power increase procedure. Finally experience related to the development and operation of the new system is discussed briefly. (C) 2007 Elsevier B.V. All rights reserved.

Al doped ZnO (ZAO) thin films were deposited by reactive magnetron sputtering from Al:Zn metallic alloy target for copper-indium-gallium-diselenide (CIGS) solar cell contacts. The effect of variation of technological parameters (power, plasma Ar/O-2 ratio and target voltage) was studied.A novel approach for controllable reactive sputter deposition is suggested using a hysteresis loop in the target voltage vs. oxygen gas flow. As a result of this optimization a 1.85 x 10(-4) ohm cm layer with 90% transparency was obtained without plasma emission monitoring and substrate heating.Thickness and specific resistance were measured on the samples prior to spectroscopic ellipsometry (SE) analysis. Evaluation of SE data was done by least square fitting the Cauchy dispersion relation using polynomial functions. Subsequently a two-step "screaning" method, based on the parameters of the complex refractive index, is suggested for evaluation of the process. Furthermore, surface roughness data can also be determined by SE, as verified by comparison with SEM morphologies. Using this method SE offers a non-destructive in-line characterization tool for the deposition process. (c) 2007 Elsevier B.V. All rights reserved.

The nrDNA ITS1 of Picea is 2747–3271bp, the longest known of all plants. We obtained 24 cloned ITS1 sequences from six individuals of Picea glehnii, Picea mariana, Picea orientalis, and Picea rubens. Mean sequence divergence within these individuals (0.018±0.009) is more than half that between the species (0.031±0.011) and may be maintained against concerted evolution by separation of Picea 18S–26S rDNA repeats on multiple chromosomes. Picea ITS1 contains three subrepeats with a motif (5′-GGCCACCCTAGTC) that is conserved across Pinaceae. Two subrepeats are tandem, remote from the third, and more closely related and significantly more similar to one another than either is to the third subrepeat. This correlation between similarity and proximity may be the result of subrepeat duplication or concerted evolution within rDNA repeats. In inferred secondary structures, subrepeats generally form long hairpins, with a portion of the Pinaceae conserved motif in the terminal loop, and tandem subrepeats pair with one another over most of their length. Coalescence of ITS1 sequences occurs in P. orientalis but not in the other species.