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Deposition Treatment (deposition + treatment)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Life Sciences	50%

Selected Abstracts

Accentuation of phosphorus limitation in Geranium dissectum by nitrogen: an ecological genomics study

GLOBAL CHANGE BIOLOGY, Issue 8 2008
SUSAN SUMMERS THAYER
Abstract Global climate change experiments have shown changes in productivity, phenology, species composition, and nutrient acquisition and availability; yet, the underlying mechanisms for these responses, especially in multi-factorial experiments, are poorly understood. Altered nutrient availability is a major consequence of global change, directly due to anthropogenic nitrogen (N) deposition, and indirectly due to shifts in temperature and water availability. In the Jasper Ridge Global Change Experiment, microarrays were used to investigate the transcriptional responses of the dominant dicot, Geranium dissectum, to simulated N deposition. The transcript levels for several photosynthetic genes were elevated in plants exposed to elevated N, as has been reported previously, validating the use of microarrays under field conditions. A coordinated response of a suite of genes previously reported to be induced in response to phosphate (Pi) deficiency was observed, including genes for the glycolytic bypass pathway, which reduces ATP and Pi requirements for sugar degradation, suggesting that the plants were phosphorus (P) limited. Confirming this conclusion, foliar P levels in G. dissectum leaves were reduced to levels that are suboptimal for growth in plants grown in elevated N and elevated CO2 plots. Thus, although plants commonly produce more biomass in response to elevated N in native grasslands, this growth response may be suboptimal due to a P limitation. Foliar P levels in plants from elevated CO2 plots were also suboptimal for growth. However, genes indicative of Pi deficiency were not significantly expressed at higher levels. Transcript levels for genes involved in nitrate uptake and assimilation were unchanged by the elevated N deposition treatment, possibly due to the combined impacts of elevated N deposition and P limitation under field conditions. These observations highlight the complexity of the impact of global climate change factors in the field. [source]

Functionalization of Copper Surfaces by Plasma Treatments to Improve Adhesion of Epoxy Resins

PLASMA PROCESSES AND POLYMERS, Issue S1 2009
Juliano Nestor Borges
Abstract Adhesion of epoxy resins on copper foils for printed circuit board (PCB) applications is improved by nearly a factor of 5, using surface cleaning and deposition of a 15-nm-thick film in a low-pressure remote plasma-enhanced chemical vapor deposition process. The cleaning pretreatment, using an N2,O2 oxidizing gas mixture with moderate heating (343 K), gives the best results. This pretreatment removes the carbonaceous contaminants present on the topmost surface of the sample and slightly oxidizes the copper into CuO. This oxide is then reduced during the deposition treatment, presumably by reaction with the aminopropyltrimethoxysilane (APTMS) precursor. The surface roughness is unchanged after treatment, thereby showing that the improvement of the copper/epoxy adhesion is only due to the chemistry of the plasma coating. Applying these results to dielectric barrier discharges allows us to achieve the same level of adhesion, which, therefore, does not depend on the process. [source]

Effects of nitrogen deposition on the interaction between an aphid and its host plant

ECOLOGICAL ENTOMOLOGY, Issue 1 2008
CARALYN B. ZEHNDER
Abstract 1.,Anthropogenic increases in nitrogen deposition are impacting terrestrial ecosystems worldwide. While some of the direct ecosystem-level effects of nitrogen deposition are understood, the effects of nitrogen deposition on plant,insect interactions and on herbivore population dynamics have received less attention. 2.,Nitrogen deposition will potentially influence both plant resource availability and herbivore population growth. If increases in herbivore population growth outstrip increases in resource availability, then increases in the strength of density dependence expressed within the herbivore population would be predicted. Alternatively, if plant resources respond more vigorously to nitrogen deposition than do herbivore populations, a decline in the strength of density dependence would be expected. No change in the strength of density dependence acting upon the herbivore population would suggest equivalent responses by herbivores and plants. 3.,A density manipulation experiment was performed to examine the effect of nitrogen deposition on the interaction between a host plant, Asclepias tuberosa, and its herbivore, Aphis nerii. Aphid maximum per capita growth rate (Rmax), carrying capacity (K), and the strength of density dependence were measured under three nitrogen deposition treatments. The effect of nitrogen deposition on the relationship among these three measures of insect population dynamics was explored. 4.,Simulated nitrogen deposition increased aphid per capita population growth, plant foliar nitrogen concentrations, and plant biomass. Nitrogen deposition caused Rmax and K to increase proportionally, leading to no overall change in the strength of density dependence. In this system, potential changes in the negative feedback processes operating on herbivore populations following nitrogen deposition appear to be buffered by concomitant changes in resource availability. [source]

The effect of surface treatments on the fretting behavior of Ti-6Al-4V alloy

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2008
Matteo Dalmiglio
Abstract Stem modularity in total hip replacement introduces an additional taper joint between Ti-6Al-4V stem components with the potential for fretting corrosion processes. One possible way to reduce the susceptibility of the Ti-6Al-4V/Ti-6Al-4V interface to fretting is the surface modification of the Ti-6Al-4V alloy. Among the tested, industrially available surface treatments, a combination of two deep anodic spark deposition treatments followed by barrel polishing resulted in a four times lower material release with respect to untreated, machined fretting pad surfaces. The fretting release has been quantified by means of radiotracers introduced in the alloy surface by proton irradiation. In a simple sphere on flat geometry, the semispherical fretting pads were pressed against flat, dog-bone shaped Ti-6Al-4V fatigue samples cyclically loaded at 4 Hz. In this way a cyclic displacement amplitude along the surfaces of 20 ,m has been achieved. A further simplification consisted in the use of deionized water as lubricant. A comparison of the radiotracer results with an electrochemical material characterization after selected treatments by potentiostatic tests of modular stems in 0.9% NaCl at 40°C for 10 days confirmed the benefit of deep anodic spark deposition and subsequent barrel polishing for improving the fretting behavior of Ti-6Al-4V. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source]