WorldWideScience

Sample records for acidic deposition gradient

  1. Spatial gradient in nitrogen deposition affects plant species frequency in acidic grasslands.

    Science.gov (United States)

    Pannek, A; Duprè, C; Gowing, D J G; Stevens, C J; Diekmann, M

    2015-01-01

    Anthropogenic eutrophication impacts ecosystems worldwide. Here, we use a vegetation dataset from semi-natural grasslands on acidic soils sampled along a gradient in north-western Europe to examine the response of species frequency to nitrogen (N) deposition, controlling for the effects of other environmental variables. A second dataset of acidic grasslands from Germany and the Netherlands containing plots from different time periods was analysed to examine whether the results of the spatial gradient approach coincided with temporal changes in the abundance of species. Out of 44 studied species, 16 were affected by N deposition, 12 of them negatively. Soil pH and phosphorus (P) influenced 24 and 14 species, respectively, predominantly positively. Fewer species were related to the soil contents of NO3(-) or NH4(+), with no significant differences between the number of positive and negative effects. Whereas the temporal change of species was unrelated to their responses to pH, species responding negatively to N deposition, soil P and NO3(-) showed a significant decline over time in both countries. Species that were negatively affected by high N deposition and/or high soil P also showed a negative temporal trend and could be characterised by short stature and slow growth. The results confirm the negative role of N deposition for many plant species in semi-natural acidic grasslands. The negative temporal trends of species sensitive to high N deposition and soil P values clearly show a need for maintaining low soil nutrient status and for restoring the formerly infertile conditions in nutrient-enriched grasslands. PMID:25407619

  2. Relationships between soil properties and community structure of soil macroinvertebrates in oak-history forests along an acidic deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Kuperman, R.G. [Argonne National Lab., IL (United States). Environmental Assessment Div.

    1996-02-01

    Soil macroinvertebrate communities were studied in ecologically analogous oak-hickory forests across a three-state atmospheric pollution gradient in Illinois, Indiana, and Ohio. The goal was to investigate changes in the community structure of soil fauna in study sites receiving different amounts of acidic deposition for several decades and the possible relationships between these changes and physico-chemical properties of soil. The study revealed significant differences in the numbers of soil animals among the three study sites. The sharply differentiated pattern of soil macroinvertebrate fauna seems closely linked to soil chemistry. Significant correlations of the abundance of soil macroinvertebrates with soil parameters suggest that their populations could have been affected by acidic deposition in the region. Abundance of total soil macroinvertebrates decreased with the increased cumulative loading of acidic deposition. Among the groups most sensitive to deposition were: earthworms gastropods, dipteran larvae, termites, and predatory beetles. The results of the study support the hypothesis that chronic long-term acidic deposition could aversely affect the soil decomposer community which could cause lower organic matter turnover rates leading to an increase in soil organic matter content in high deposition sites.

  3. Leaf area and foliar biomass relationships in northern hardwood forests located along an 800 km acid deposition gradient

    International Nuclear Information System (INIS)

    The canopies of northern hardwood forests dominated by sugar maple (Acer saccharum Marsh.) were examined at five locations spanning 800 km along an acid deposition and climatic gradient in the Great Lakes region. Leaf area index (LAI) calculated from litterfall ranged from 6.0 to 8.0 in 1988, from 4.9 to 7.9 in 1989, and from 5.3 to 7.8 in 1990. The data suggest that maximum LAI for the sites is between 7 and 8. Insect defoliation and the allocation of assimilates to reproductive parts in large seed years reduced LAI by up to 34%. Allometric equations for leaf area and foliar biomass were not significantly different among sites. They predicted higher LAI values than were estimated from litterfall and could not account for the influences of defoliation and seed production. Canopy transmittance was a viable alternative for estimating LAI. Extinction coefficients (K) of 0.49 to 0.65 were appropriate for solar elevations of 63 degree to 41 degree. Patterns of specific leaf area (SLA) were similar for the sites. Average sugar maple SLA increased from 147 cm2g-1 in the upper 5 m of the canopy to 389 cm2g-1 in the seeding layer. Litterfall SLA averaged 196 cm2g-1 for all species and 192 cm2g-1 for sugar maple. Similarity among the sites in allometric relationships, maximum LAI, canopy transmittance, and patterns of SLA suggests these characteristics were controlled primarily by the similar nutrient and moisture availability at the sites. A general increasing trend in litter production along the gradient could not be attributed to N deposition or length of growing season due to year to year variability resulting from insect defoliation and seed production

  4. Acid Deposition Phenomena

    International Nuclear Information System (INIS)

    Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO2) and nitrogen oxides (NOx). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H2SO4) and nitric acids (HNO3), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry

  5. A Complexity View of Acid Deposition

    Institute of Scientific and Technical Information of China (English)

    朱建林; 方见树

    2003-01-01

    We show that acid deposition is analogous to complex systems composed of a series of interconnected components.Frequency-size distributions of weekly hydrogen deposition (WHD) of precipitation are consistent with double power-law in two different regimes separated by a crossover WHD. The distribution of variations in acid deposition over a week interval is remarkably symmetrical, with long tail extending over eight orders of magnitude. The acid deposition fluctuations exhibit fractal Brown motion with two different temporal scaling regimes and long-range correlation exists in the series. The power-laws in the acid deposition dynamics are considered to be indicators of seff-organization of atmosphere under environmental pollution stress.

  6. Acid Deposition Maps in Spain

    International Nuclear Information System (INIS)

    Animal and monthly deposition velocity and total sulfur deposition maps have been performed for the peninsular Spain for 1992 by using the inferential method. To do this, updated databases with high space and time resolution, for land uses (CORINE) and meteorological information from analysis modelling for the same year, have been utilized. The final result are deposition maps in a 5x5 Km2 grid which allow to assess the methodology used in Europe to obtain the maps of excedances over the critical loads of pollutants. (Author) 32 refs

  7. Hard gradient (Ti,Al,SiN coating deposited on composite tool materials

    Directory of Open Access Journals (Sweden)

    T. Gawarecki

    2009-04-01

    Full Text Available Purpose: This paper presents investigation of gradient coating of (Ti,Al,SiN deposited on the Al2O3+SiC(w oxide ceramics substrate deposited with the PVD process.Design/methodology/approach: Structure of substrate and coating was investigated with use of scanning electron microscopy (SEM; The X-Ray Photoelectron Spectrometry (XPS and Auger Electron Spectrometry (AES examinations was carried out for proving the gradient character of the (Ti,Al,SiN coating. The investigation includes also microhardness and roughness tests of the deposited coating and used substrate. Scratch test results was analysed to introduce adherence of the investigated coating.Findings: Gradient structure and main properties of the investigated materials were introduced. It has been stated, that properties of the coated with gradient (Ti,Al,SiN coating oxide tool ceramic increase in comparison with uncoated material.Practical implications: Depositing the wear resistant gradient coating onto the Al2O3+SiC(w oxide tool ceramic results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools’ flanks made from the Al2O3+SiC(w oxide tool ceramic.Originality/value: Gradient coatings are an innovative idea. The composition, microstructure and properties of gradient materials change continuously from the surface to the interior of the material.

  8. Fabrication of Isotropic Pyrocarbon at 1400℃ by Thermal Gradient Chemical Vapor Deposition Apparatus

    Institute of Scientific and Technical Information of China (English)

    GUO Lingjun; ZHANG Dongsheng; LI Kezhi; LI Hejun

    2009-01-01

    An experiment was designed to prepare isotropic pyrocarbon by thermal gradient chemical vapor deposition apparatus.The deposition was performed under ambient atmosphere at 1400℃,with natural gas volume flow of 3.5 m~3/h for 80 h.The results show that the thickness and the bulk density of the deposit are about 1.95 g/cm~3 and 10 mm,respectively.The microstructure of the deposit was examined by polarized light microscopy and scanning electron microscopy,which shows that the deposit is constituted of sphere isotropic pyrocarbon,pebble pyrocarbon and laminar pyrocarbon.

  9. Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing

    OpenAIRE

    Douglas C. Hofmann; Scott Roberts; Richard Otis; Joanna Kolodziejska; R. Peter Dillon; Jong-ook Suh; Shapiro, Andrew A; Zi-Kui Liu; John-Paul Borgonia

    2014-01-01

    Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to a...

  10. Dynamics and precision in retinoic acid morphogen gradients

    OpenAIRE

    SCHILLING, THOMAS F.; Nie, Qing; Lander, Arthur D.

    2012-01-01

    Retinoic acid (RA) regulates many cellular behaviors during embryonic development and adult homeostasis. Like other morphogens, RA forms gradients through the use of localized sources and sinks, feedback, and interactions with other signals; this has been particularly well studied in the context of hindbrain segmentation in vertebrate embryos. Yet, as a small lipophilic molecule derived from a dietary source—vitamin A—RA differs markedly from better-studied polypeptide morphogens in its mecha...

  11. Study of preparation of BG/HA gradient coating on titanium alloy by electrophoretic deposition method

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ming; HAN Qing-rong; LI Shi-pu; XU Chuan-bo

    2001-01-01

    In this paper, a gradient bioactive coating made from modified bioglass (BG) and hydroxyapatite (HA) was prepared by electrophoretic deposition method(EPD)on the surface of titanium alloy. Strong bonding between the matrix and BG/HA gradient coating was got by sintering. Crystal composition of the coating was analyzed by XRD. The characteristics of surface and cross section of the coating were observed by SEM. Adhesive strength of the coating was tested by pull method. The optimizing technological parameters were determined.

  12. Inferred effects of cloud deposition on forest floor nutrient cycling and microbial properties along a short elevation gradient

    International Nuclear Information System (INIS)

    Higher cloud cover significantly decreases forest floor pH, decrease exchangeable cations, modifies mineral-N speciation and increases physiological stress within microbial communities. - Cloud water deposition often increases with elevation, and it is widely accepted that this cloud water increases acid loading to upland forest ecosystems. A study was undertaken in south-eastern Quebec to determine if a 250 m elevation gradient (i.e. 420-665 m), along a uniform sugar-maple stand on the slope of Mount Orford, corresponded to a pH gradient in the forest floor and to predictable changes in soil nutrient availability and microbial properties. Precipitation data from a nearby study, and a photographic survey, provided presumptive evidence that this elevation gradient corresponded to a strong gradient in cloud water deposition. Forest floor temperature did not differ significantly across elevations. Forest floor moisture content was significantly higher, whereas pH and exchangeable Ca and Mg were significantly lower, at the higher elevations. Average seasonal net nitrification rates, determined by long-term laboratory incubations, did not differ significantly across elevations, whereas average seasonal net ammonification rates were significantly higher at higher elevations. Basal respiration rates and microbial biomass did not differ significantly across elevations, but metabolic quotient was significantly higher at higher elevations indicating possible environmental stress on forest floor microbial communities due to cloud water deposition. Anaerobic N mineralisation rates were significantly higher at higher elevations suggesting that N-limited microbial communities frequently exposed to cloud cover can be important short-term sinks for atmospheric N, thereby contributing to increase the active-N fraction of forest floors. We conclude that, where no significant changes in vegetation or temperature occur, elevation gradients can still be used to understand the spatial

  13. High Gradient Accelerator Cavities Using Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Parsons, Gregory [North Carolina State Univ., Raleigh, NC (United States); Williams, Philip [North Carolina State Univ., Raleigh, NC (United States); Oldham, Christopher [North Carolina State Univ., Raleigh, NC (United States); Mundy, Zach [North Carolina State Univ., Raleigh, NC (United States); Dolgashev, Valery [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2014-12-09

    In the Phase I program, Calabazas Creek Research, Inc. (CCR), in collaboration with North Carolina State University (NCSU), fabricated copper accelerator cavities and used Atomic Layer Deposition (ALD) to apply thin metal coatings of tungsten and platinum. It was hypothesized that a tungsten coating would provide a robust surface more resistant to arcing and arc damage. The platinum coating was predicted to reduce processing time by inhibiting oxides that form on copper surfaces soon after machining. Two sets of cavity parts were fabricated. One was coated with 35 nm of tungsten, and the other with approximately 10 nm of platinum. Only the platinum cavity parts could be high power tested during the Phase I program due to schedule and funding constraints. The platinum coated cavity exhibit poor performance when compared with pure copper cavities. Not only did arcing occur at lower power levels, but the processing time was actually longer. There were several issues that contributed to the poor performance. First, machining of the base copper cavity parts failed to achieve the quality and cleanliness standards specified to SLAC National Accelerator Center. Secondly, the ALD facilities were not configured to provide the high levels of cleanliness required. Finally, the nanometer coating applied was likely far too thin to provide the performance required. The coating was ablated or peeled from the surface in regions of high fields. It was concluded that the current ALD process could not provide improved performance over cavities produced at national laboratories using dedicated facilities.

  14. Aeromagnetic gradient survey and elementary application in sandstone type uranium deposits prospecting

    International Nuclear Information System (INIS)

    The principle,advantage and data processing of aeromagnetic gradient survey approach is introduced in this paper, and used to identify the shallow surface faults, uranium ore-forming environment and depth of magnetic body for the prospecting of sandstone type uranium deposits. (authors)

  15. Acid deposition study in the Asian countries

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Ting-Kueh [Tunku Abdul Rahman College, Kuala Lumpur (Malaysia); Lau, Wai-Yoo [Malaysian Scientific Association, Kuala Lumpur (Malaysia)

    1996-12-31

    The Association of South East Asian Nations or ASEAN is a regional association of seven countries, namely Indonesia, Malaysia, Philippines, Singapore, Thailand, Brunei and Vietnam, located at the south eastern part of the Asian continent. Together with the East Asian States of Japan, China, Korea and Taiwan, this part of the world is experiencing rapid economic growth, especially in the last decade. Rapid industrialization has resulted in an increased demand for energy in the manufacturing and transport sectors, and also for infrastructure development. This has led to a significant increase in gaseous emissions and a corresponding increase in atmospheric acidity. Acid deposition study in the ASEAN countries began in the mid-70s when Malaysia first started her acid rain monitoring network in 1976. This was followed closely by Singapore and the other ASEAN countries in the 80s. By now all ASEAN countries have their own acid rain monitoring networks with a number of these countries extending the monitoring to dry deposition as well.

  16. Acid deposition and its implications for nature conservation in Britain

    Energy Technology Data Exchange (ETDEWEB)

    Fry, G.L.A.; Cooke, A.S.

    1984-01-01

    A general consideration of acid deposition is given, in terms of the origins and fate of acid deposition and its effects on terrestrial, freshwater and marine ecosystems. Acid deposition in wetland sites in Britain is discussed, and conclusions are drawn for nature conservation in Britain. (177 refs.)

  17. A modified micrometeorological gradient method for estimating O3 dry deposition over a forest canopy

    Directory of Open Access Journals (Sweden)

    Z. Y. Wu

    2015-01-01

    Full Text Available Small pollutant concentration gradients between levels above a plant canopy result in large uncertainties in estimated air–surface exchange fluxes when using existing micrometeorological gradient methods, including the aerodynamic gradient method (AGM and the modified Bowen-Ratio method (MBR. A modified micrometeorological gradient method (MGM is proposed in this study for estimating O3 dry deposition fluxes over a forest canopy using concentration gradients between a level above and a level below the canopy top, taking advantage of relatively large gradients between these levels due to significant pollutant uptake at top layers of the canopy. The new method is compared with the AGM and MBR methods and is also evaluated using eddy-covariance (EC flux measurements collected at the Harvard Forest Environmental Measurement Site, Massachusetts during 1993–2000. All the three gradient methods (AGM, MBR and MGM produced similar diurnal cycles of O3 dry deposition velocity (Vd(O3 to the EC measurements, with the MGM method being the closest in magnitude to the EC measurements. The multi-year average Vd(O3 differed significantly between these methods, with the AGM, MBR and MGM method being 2.28, 1.45 and 1.18 times of that of the EC. Sensitivity experiments identified several input parameters for the MGM method as first-order parameters that affect the estimated Vd(O3. A 10% uncertainty in the wind speed attenuation coefficient or canopy displacement height can cause about 10% uncertainty in the estimated Vd(O3. An unrealistic leaf area density vertical profile can cause an uncertainty of a factor of 2.0 in the estimated Vd(O3. Other input parameters or formulas for stability functions only caused an uncertainly of a few percent. The new method provides an alternative approach in monitoring/estimating long-term deposition fluxes of similar pollutants over tall canopies.

  18. Soil N chemistry in oak forests along a nitrogen deposition gradient

    DEFF Research Database (Denmark)

    Nilsson, Lars Ola; Wallander, Håkan; Bååth, Erland;

    2006-01-01

    ¹³¹³dAnthropogenic N deposition may change soil conditions in forest ecosystems as demonstrated in many studies of coniferous forests, whereas results from deciduous forests are relatively scarce. Therefore the influence of N deposition on several variables was studied in situ in 45 oak......-dominated deciduous forests along a N deposition gradient in southern Sweden, where the deposition ranged from 10 to 20 kg N ha-¹ year-¹. Locally estimated NO3-deposition, as measured with ion-exchange resins (IER) on the soil surface, and grass N concentration (%) were positively correlated with earlier modelled...... oak-dominated forests has not yet resulted in extensive leaching of N. The d15N enrichment factor was the variable best correlated with NO-3 concentrations at 50 cm and is thus a variable that potentially may be used to predict leaching of NO-3 from forest soils....

  19. Electrospray deposition of chalcogenide glass films for gradient refractive index and quantum dot incorporation

    Science.gov (United States)

    Novak, Spencer

    -to-roll processing whereby (theoretically) 100% of starting solution can be utilized in a continuous process. The present effort has shown that electrospray offers the advantage of spatially defined, localized deposition, which enables direct 2-D and 3-D printing, though with limited (unoptimized) spatial resolution on the order of millimeters. Knowledge of processing protocols were exploited to fabricate multi-layer films from two different glass compositions to yield an effective refractive index gradient (GRIN). GRIN coatings were fabricated and refractive index variations were predicted. The advantages of electrospray deposition were also explored for the enhancement of quantum dot doping in ChG films. A hypothesis whereby electrospray would enable deposition of films based on consolidation of many, single QD doped aerosol droplets was developed and evaluated. Experimental validation of this premise in CdSe and PbS doped ChG films was shown, indicating that electrospray offers a kinetic barrier to QD movement preventing aggregation from occurring, not seen in spin-coating. Two types of organic ligands were found to enhance dispersion of QDs in amine solvents, octadecylamine and mercaptopropionic acid. Utilizing TEM characterization, evidence that electrospray may be more suitable than spin-coating for the dispersion of QDs in solution-derived ChG films was confirmed. However, the ultimate effectiveness of this approach was limited due to the ability to quantify direct loading levels of the QD and surrounding glass matrix. This work demonstrates that electrospray offers additional flexibility over spin-coating and other evaporation methods for the deposition of ChG coatings. Electrospray processing of doped and undoped ChG solutions for microphotonic applications has been shown as a viable alternative in the processing and material toolbox where spatially defined index and dopant control is required.

  20. Isotopic Investigation of Reactive Nitrogen Deposition Along a Highway Road Gradient

    Science.gov (United States)

    Middlecamp, K. M.; Elliott, E. M.

    2009-12-01

    It is well understood that mobile emissions on highways create “hotspots” of air pollution. For example, previous studies have indicated that nitrogen emissions from automobiles are deposited locally within 10’s to 100’s of meters from roadways in the form of particulates and aerosols in dry deposition. However, there is limited understanding of the effects of these emissions on the surrounding environment and human health. This spatial pattern of concentrated nitrogen deposition has important implications for near-road environments. For example, storm water infrastructure likely channels near-road deposition directly into surface waters. In addition, excess nitrogen can have adverse affects on near-road plant communities; studies have documented defoliation and changes in community structure due to nitrogen pollution near roadways. Because vehicle emissions constitute about half of Eastern U.S. NOx emissions, it is critical to identify the fate and impact of automobile emissions on near-road ecosystems. Furthermore, legislation controlling air pollution around highways is limited, and has recently been the focus of debate regarding the necessity of reducing highway pollution to National Ambient Air Quality Standard levels. This research addresses the spatial pattern and sources of reactive N deposition near a roadway. The study uses stable isotopes of nitrogen in plant tissue and dry nitrogen deposition to examine the extent of N deposition along a gradient perpendicular to a major highway. The gradient spans 400 meters perpendicular to a heavily trafficked section (33,000 cars and trucks per day) of I-76 in Rector, Pennsylvania. Passive samplers were deployed monthly for five months at six sites along the gradient to collect dry deposition of three reactive N species: NH3, HNO3 and NO2. The passive samplers were analyzed for concentration and isotopic composition (δ13N). Additionally, we used two types of grasses (Agrostis perennans and Panicum virgatum

  1. The impact of nitrogen deposition on acid grasslands in the Atlantic region of Europe

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Carly J., E-mail: c.j.stevens@open.ac.uk [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Dupre, Cecilia [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Dorland, Edu [Ecology and Biodiversity Group, Department of Biology, Institute of Environmental Biology, Utrecht University, PO Box 80.058, 3508 TB Utrecht (Netherlands); Gaudnik, Cassandre [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Gowing, David J.G. [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Bleeker, Albert [Department of Air Quality and Climate Change, Energy Research Centre of the Netherlands, PO Box 1, 1755 ZG Petten (Netherlands); Diekmann, Martin [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Alard, Didier [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Bobbink, Roland [B-WARE Research Centre, Radboud University, PO Box 9010, 6525 ED Nijmegen (Netherlands); Fowler, David [NERC Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Corcket, Emmanuel [University of Bordeaux 1, UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Mountford, J. Owen [NERC Centre for Ecology and Hydrology, MacLean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Vandvik, Vigdis [Department of Biology, University of Bergen, Box 7800, N-5020 Bergen (Norway)

    2011-10-15

    A survey of 153 acid grasslands from the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is changing plant species composition and soil and plant-tissue chemistry. Across the deposition gradient (2-44 kg N ha{sup -1} yr{sup -1}) grass richness as a proportion of total species richness increased whereas forb richness decreased. Soil C:N ratio increased, but soil extractable nitrate and ammonium concentrations did not show any relationship with nitrogen deposition. The above-ground tissue nitrogen contents of three plant species were examined: Agrostis capillaris (grass), Galium saxatile (forb) and Rhytidiadelphus squarrosus (bryophyte). The tissue nitrogen content of neither vascular plant species showed any relationship with nitrogen deposition, but there was a weak positive relationship between R. squarrosus nitrogen content and nitrogen deposition. None of the species showed strong relationships between above-ground tissue N:P or C:N and nitrogen deposition, indicating that they are not good indicators of deposition rate. - Highlights: > N deposition is negatively correlated with forb richness as a proportion of species richness. > Soil C:N ratio increased with increasing N deposition. > Soil extractable nitrate and ammonium were not related to nitrogen deposition. > Plant-tissue N content was not a good indicator of N deposition. - Atmospheric nitrogen deposition affects soils, plant-tissue chemistry and plant species composition in acid grasslands in the Atlantic biogeographic region of Europe.

  2. The effect of deposition parameters on the properties of gradient a-C:H/Ti layers

    OpenAIRE

    D. Batory; A. Stanishevsky; W. Kaczorowski

    2009-01-01

    Purpose: During the last 20 years DLC (diamond-like carbon) layers became a very attractive material in many medical and engineering applications. While the layer’s stress and adhesion were always a concern, several adhesion improvement methods have been proposed. A majority of those methods consists of either the deposition of an adhesion promoting interlayer or the application of a gradient of chemical composition. In whatever way this reduces the internal stress and improves the adhesion o...

  3. Elemental concentrations in deposited dust on leaves along an urbanization gradient.

    Science.gov (United States)

    Simon, Edina; Baranyai, Edina; Braun, Mihály; Cserháti, Csaba; Fábián, István; Tóthmérész, Béla

    2014-08-15

    Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP-OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree.

  4. Improvement of tool materials by deposition of gradient and multilayers coatings

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2006-10-01

    Full Text Available Purpose: Investigation of the functional properties of cermets, Si3N4 and Al2O3 based ceramics, coated with the PVD andCVD multilayer and gradient coatings and comparison them with the commercial uncoated and coated tool materials.Design/methodology/approach: TEM, SEM, confocal microscopy, scratch test, microhardness tests, roughnesstests, cutting tests.Findings: Employment of the hard wear resistant coatings deposited onto the sintered ceramic tool materials withthe physical deposition from the gaseous phase (PVD is reckoned as one of the most important achievements inthe last years in the area of improvement of the service properties of ceramic cutting tools. Depositing the antiwearcoatings of the gradient and multi TiN+(Ti,Al,SiN+TiN types onto the investigated ceramic tool materialsmakes it possible to achieve the clear improvement of their tool life and also of the quality of the machinedsurfaces, reduction of machining costs and elimination of cutting fluids used in machining.Practical implications: The widespread use in machining of oxide and nitride ceramics, as well as of cermetswith the complex nanocrystaline coatings deposited in the PVD processes contributes to the increased interestin the contemporary „Near-Net-Shape” technology, i.e., manufacturing semi-products with the shape anddimensions as close as possible to those of the finished products.Originality/value: In the paper the research of multilayer and gradient TiN+(Ti,Al,SiN+TiN nanocrystalline coatingsdeposited in the PVD method on sintered tool materials carried out in order to improve the tool cutting properties.

  5. Atmospheric deposition and watershed nitrogen export along an elevational gradient in the Catskill Mountains, New York

    Science.gov (United States)

    Lawrence, G.B.; Lovett, Gary M.; Baevsky, Y.H.

    2000-01-01

    Cumulative effects of atmospheric N deposition may increase N export from watersheds and contribute to the acidification of surface waters, but natural factors (such as forest productivity and soil drainage) that affect forest N cycling can also control watershed N export. To identify factors that are related to stream-water export of N, elevational gradients in atmospheric deposition and natural processes were evaluated in a steep, first-order watershed in the Catskill Mountains of New York, from 1991 to 1994. Atmospheric deposition of SO4/2-, and probably N, increased with increasing elevation within this watershed. Stream-water concentrations of SO4/2- increased with increasing elevation throughout the year, whereas stream-water concentrations of NO3/- decreased with increasing elevation during the winter and spring snowmelt period, and showed no relation with elevation during the growing season or the fall. Annual export of N in stream water for the overall watershed equaled 12% to 17% of the total atmospheric input on the basis of two methods of estimation. This percentage decreased with increasing elevation, from about 25% in the lowest subwatershed to 7% in the highest subwatershed; a probable result of an upslope increase in the thickness of the surface organic horizon, attributable to an elevational gradient in temperature that slows decomposition rates at upper elevations. Balsam fir stands, more prevalent at upper elevations than lower elevations, may also affect the gradient of subwatershed N export by altering nitrification rates in the soil. Variations in climate and vegetation must be considered to determine how future trends in atmospheric deposition will effect watershed export of nitrogen.

  6. Effects of acid deposition on tree roots

    Energy Technology Data Exchange (ETDEWEB)

    Persson, H. [Swedish Univ. of Agricultural Sciences (Sweden). Dept. of Ecology and Environmental Research

    1995-12-31

    Large forest regions in SW Sweden have been exposed to high levels of acid deposition for many decades, causing soil acidification in forest soils. Historically, SO{sub 2} has been the major acidification agent, but lately nitrogen compounds increasingly have become important. The amount and chemical form of nitrogen strongly affects the pH in the rhizosphere and rhizoplane. Many forest stands show a positive growth response to increased nitrogen input, even in heavily N-loaded areas. Nitrogen fertilization experiments suggest that part of the increased forest production is caused by a translocation of biomass production from below-ground to above-ground parts. At the same time fine-root growth dynamics are strongly affected by the high N supply. Deficiencies of various nutrients (Mg,Ca,K,Mn and Zn) obtained from needle analyses have been reported from different Picea abies stands. In areas with more extensive acidification and nutrient leaching, a decline in tree vitality has been observed. Although deficiency symptoms in forest trees may be reflected in nitrogen/cation ratios in fine roots, few attempts have been made to explain forest damage symptoms from fine-root chemistry. Root damage is often described as a decline in the amount of living fine roots, an increase in the amount of dead versus live fine roots (a lower live/dead ratio) and an increasing amount of dead medium and coarse roots. The primary objectives of the present presentation were to analyse available data on the effects of high nitrogen and sulphur deposition on mineral nutrient balance in tree fine roots and to evaluate the risk of Al interference with cation uptake by roots

  7. Low-Vacuum Deposition of Glutamic Acid and Pyroglutamic Acid: A Facile Methodology for Depositing Organic Materials beyond Amino Acids

    OpenAIRE

    Iwao Sugimoto; Shunsaku Maeda; Yoriko Suda; Kenji Makihara; Kazuhiko Takahashi

    2014-01-01

    Thin layers of pyroglutamic acid (Pygl) have been deposited by thermal evaporation of the molten L-glutamic acid (L-Glu) through intramolecular lactamization. This deposition was carried out with the versatile handmade low-vacuum coater, which was simply composed of a soldering iron placed in a vacuum degassing resin chamber evacuated by an oil-free diaphragm pump. Molecular structural analyses have revealed that thin solid film evaporated from the molten L-Glu is mainly composed of L-Pygl du...

  8. Simulated dry deposition of nitric acid near forest edges

    NARCIS (Netherlands)

    DeJong, JJM; Klaassen, W; Jong, J.J.M. de

    1997-01-01

    Dry deposition is simulated to understand and generalize observations of enhanced deposition of air pollution near forest edges. Nitric acid is taken as an example as its deposition velocity is often assumed to be determined by turbulent transport only. The simulations are based on the micro-meteoro

  9. Elemental concentrations in deposited dust on leaves along an urbanization gradient

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Edina, E-mail: edina.simon@gmail.com [Department of Ecology, University of Debrecen, H-4010 Debrecen, P.O. Box 71 (Hungary); Baranyai, Edina [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Agilent Atomic Spectroscopy Partner Laboratory, University of Debrecen, Egyetem tér 1, H-4032 Debrecen (Hungary); Braun, Mihály [Institute of Nuclear Research of the Hungarian Academy of Sciences, Herteleni Laboratory of Environmental Studies, 4026 Debrecen, Bem tér 18/C (Hungary); Cserháti, Csaba [Department of Solid State Physics, University of Debrecen, H-4010 Debrecen, P.O. Box 2 (Hungary); Fábián, István [Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21 (Hungary); Tóthmérész, Béla [HAS-UD Biodiversity and Ecosystem Services Research Group, H-4010 Debrecen, P.O. Box 71 (Hungary)

    2014-08-15

    Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP–OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree. - Highlights: • Dust is used as indicators of the accumulation of inorganic pollutants. • Scanning EM was used to explore the morphological structure of leaves. • Amount of dust deposited of leaves correlated with trichomes' density. • A. negundo, C. occidentalis and Q. robur are suitable to indicate air contaminants. • A. negundo and C. occidentalis are suitable to decrease the amount of dust in air.

  10. Elemental concentrations in deposited dust on leaves along an urbanization gradient

    International Nuclear Information System (INIS)

    Environmental health is an essential component of the quality of life in modern societies. Monitoring of environmental quality and the assessment of environmental risks are often species based on the elemental concentration of deposited dust. Our result suggested that stomata size and distribution were the most important factors influencing the accumulation of air contaminants in leaves. We found that the leaves' surfaces of Acer negundo and Celtis occidentalis were covered by a large number of trichomes, and these species have proven to be suitable biomonitors for atmospheric pollution difficult; these can be overcome using bioindicator species. Leaves of Padus serotina, Acer campestre, A. negundo, Quercus robur and C. occidentalis were used to assess the amount of deposited dust and the concentration of contaminants in deposited dust in and around the city of Debrecen, Hungary. Samples were collected from an urban, suburban and rural area along an urbanization gradient. The concentrations of Ba, Cu, Fe, Mn, Ni, Pb, S, Sr and Zn were determined in deposited dust using ICP–OES. Scanning electron microscopy (SEM) was used to explore the morphological structure and dust absorbing capacity of leaves. We found significant differences in dust deposition among species, and dust deposition correlated with trichomes' density. Principal component analysis (PCA) also showed a total separation of tree. - Highlights: • Dust is used as indicators of the accumulation of inorganic pollutants. • Scanning EM was used to explore the morphological structure of leaves. • Amount of dust deposited of leaves correlated with trichomes' density. • A. negundo, C. occidentalis and Q. robur are suitable to indicate air contaminants. • A. negundo and C. occidentalis are suitable to decrease the amount of dust in air

  11. Impact of Seasalt Deposition on Acid Soils in Maritime Regions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen-Hua

    2003-01-01

    The characteristics of seasalt deposition and its impact on acid soils in maritime regions are reviewed. It is pointed out that studies involving the impact of seasalt deposition on acid soils have been concentrated on short-term effects on soil and water acidification. A deep consideration of long-term effects on soil acidification in maritime regions is still needed.

  12. Structure and mechanical properties of PVD gradient coatings deposited onto tool steels and sialon tool ceramics

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2009-11-01

    Full Text Available Purpose: The paper presents investigation results of the structure and mechanical properties of gradient coatings deposited by cathodic arc evaporation - physical vapour deposition (CAE-PVD techniques onto the X40CrMoV5-1 hot work tool steel, HS6-5-2 high speed steel and SiAlON tool ceramics. The Ti(C,N, (Ti,AlN and (Al,Si,Cr N coatings were investigated.Design/methodology/approach: Microstructure was characterised using scanning and transmission electron microscopy. The phase composition of the investigated coatings was determined by means of the X-ray diffractometer. The chemical concentration changes of the coating components, and the substrate material were evaluated in virtue of tests carried out in the GDOS spectrometer. Tests of the coatings’ adhesion to the substrate material were made using the scratch test method.Findings: It was found out that the structure of the PVD coatings deposited onto all substrates is composed of fine crystallites. The investigations made by use of the glow discharge optical emission spectrometer indicate to the existence of the transition zone between the substrate material and the coating. The results show that all coatings present good adhesion. The critical load LC2, which is in the range 35-90 N, depends on the coating type and substrate. Good adhesion of the coatings deposited to the substrate should be connected with the existence of the transition zone. All the coatings are demonstrated by high hardness.Research limitations/implications: Ti(C,N, (Ti,AlN and (Al,Si,Cr N gradient coatings can be applied for cutting tools and hot working tools.Originality/value: Working out and testing PVD coatings obtained by tool ceramic and tool steels is a special future of development direction in a domain of thin coatings.

  13. Changes in epilithic biomasses and invertebrate community structure over a deposit metal concentration gradient in upland headwater streams

    OpenAIRE

    Macintosh, Katrina Ann; Griffiths, David

    2015-01-01

    Stream bed metal deposits affect the taxon richness, density and taxonomic diversity of primary and secondary producers by a variety of direct or indirect abiotic and biotic processes but little is known about the relative importance of these processes over a deposit metal concentration gradient. Inorganic matter (IM), algal and non-photosynthetic detrital (NPD) dry biomasses were estimated for 10 monthly samples, between 2007 and 2008, from eight sites differing in deposit density. Invertebr...

  14. Fabrication of gradient porous LSM cathode by optimizing deposition parameters in ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Multiple-step ultrasonic spray pyrolysis was developed to produce a gradient porous lanthanum strontium manganite (LSM) cathode on yttria-stabilized zirconia (YSZ) electrolyte for use in intermediate temperature solid oxide fuel cells (IT-SOFCs). The effect of solvent and precursor type on the morphology and compositional homogeneity of the LSM film was first identified. The LSM film prepared from organo-metallic precursor and organic solvent showed a homogeneous crack-free microstructure before and after heat treatment as opposed to aqueous solution. With respect to the effect of processing parameters, increasing the temperature and solution flow rate in the specific range of 520-580 deg. C leads to change the microstructure from a dense to a highly porous structure. Using a dilute organic solution a nanocrystalline thin layer was first deposited at 520 deg. C and solution flow rate of 0.73 ml/min on YSZ surface; then, three gradient porous layers were sprayed from concentrated solution at higher temperatures (540-580 deg. C) and solution flow rates (1.13-1.58 ml/min) to form a gradient porous LSM cathode film with ∼30 μm thickness. The microstructure, phase crystallinity and compositional homogeneity of the fabricated films were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive analysis of X-ray (EDX). Results showed that the spray pyrolized gradient film fabricated in the temperature range of 520-580 deg. C is composed of highly crystalline LSM phase which can remove the need for subsequent heat treatment

  15. Ancillary effects of selected acid deposition control policies

    Energy Technology Data Exchange (ETDEWEB)

    Moe, R.J.; Lyke, A.J.; Nesse, R.J.

    1986-08-01

    NAPAP is examining a number of potential ways to reduce the precursors (sulfur dioxide and nitrogen oxides) to acid deposition. However, the policies to reduce acid deposition will have other physical, biological and economic effects unrelated to acid deposition. For example, control policies that reduce sulfur dioxide emissions may also increase visibility. The effects of an acid deposition policy that are unrelated to acid deposition are referred to as ''ancillary'' effects. This reserch identifies and characterizes the principle physical and economic ancillary effects associated with acid deposition control and mitigation policies. In this study the ancillary benefits associated with four specific acid deposition policy options were investigated. The four policy options investigated are: (1) flue gas desulfurization, (2) coal blending or switching, (3) reductions in automobile emissions of NO/sub x/, and (4) lake liming. Potential ancillary benefits of each option were identified and characterized. Particular attention was paid to the literature on economic valuation of potential ancillary effects.

  16. On the Use of Mo/Mo2C Gradient Interlayers in Diamond Deposition onto Cemented Carbide Substrates

    Science.gov (United States)

    Gao, Jie; Hei, Hongjun; Zheng, Ke; Gao, Xueyan; Liu, Xiaoping; Tang, Bin; He, Zhiyong; Yu, Shengwang

    2016-01-01

    Molybdenum/molybdenum carbide (Mo/Mo2C) gradient interlayers were prepared via double glow plasma surface alloying (DGPSA) technique onto cemented carbide (WC-Co) substrates for diamond deposition. The morphologies, phase composition and adhesion of the interlayers were investigated, as well as their effect on the subsequent diamond deposition. The results indicated that the Mo/Mo2C gradient interlayer deposited on WC-Co substrate was composed of 4.0-μm-thick diffusion layer and 2.7-μm-thick deposition layer. The Mo concentration decreased gradually with the depth direction whereas the Co and W concentrations increased. As a result, the Co binder phase was completely restricted within the substrate by the diffusion layer. The presence of gradient diffusion layer ensured excellent adhesion of the interlayer. Subsequently, nanocrystalline diamond coatings with excellent adhesion were deposited on the interlayered substrates. Thus, the Mo/Mo2C gradient interlayers deposited via DGPSA technique were demonstrated as a novel option for depositing adherent diamond coatings on WC-Co substrates.

  17. Low-Vacuum Deposition of Glutamic Acid and Pyroglutamic Acid: A Facile Methodology for Depositing Organic Materials beyond Amino Acids

    Directory of Open Access Journals (Sweden)

    Iwao Sugimoto

    2014-01-01

    Full Text Available Thin layers of pyroglutamic acid (Pygl have been deposited by thermal evaporation of the molten L-glutamic acid (L-Glu through intramolecular lactamization. This deposition was carried out with the versatile handmade low-vacuum coater, which was simply composed of a soldering iron placed in a vacuum degassing resin chamber evacuated by an oil-free diaphragm pump. Molecular structural analyses have revealed that thin solid film evaporated from the molten L-Glu is mainly composed of L-Pygl due to intramolecular lactamization. The major component of the L-Pygl was in β-phase and the minor component was in γ-phase, which would have been generated from partial racemization to DL-Pygl. Electron microscopy revealed that the L-Glu-evaporated film generally consisted of the 20 nm particulates of Pygl, which contained a periodic pattern spacing of 0.2 nm intervals indicating the formation of the single-molecular interval of the crystallized molecular networks. The DL-Pygl-evaporated film was composed of the original DL-Pygl preserving its crystal structures. This methodology is promising for depositing a wide range of the evaporable organic materials beyond amino acids. The quartz crystal resonator coated with the L-Glu-evaporated film exhibited the pressure-sensing capability based on the adsorption-desorption of the surrounding gas at the film surface.

  18. Soil Properties in Coniferous Forest Stands Along a Fly Ash Deposition Gradient in Eastern Germany

    Institute of Scientific and Technical Information of China (English)

    S. KLOSE; F. MAKESCHIN

    2005-01-01

    Physical, chemical, and microbial properties of forest soils subjected to long-term fly ash depositions were analyzed in spruce (Picea abies (L.) Karst.) stands of eastern Germany on three forest sites along an emission gradient of 3 (high input), 6, and 15 km (low input) downwind of a coal-fired power plant. Past emissions resulted in an atypical high mass of mineral fly ash constituents in the organic horizons at the high input site of 128 t ha-1 compared to 58 t ha-1 at the low input site. Magnetic susceptibility measurements proved that the high mineral content of the forest floor was a result of fly ash accumulation in these forest stands. Fly ash deposition in the organic horizons at Site Ⅰ versus Ⅲsignificantly increased the pH values, effective cation exchange capacity, base saturation and, with exception of the L horizon, concentrations of mobile heavy metals Cd, Cr, and Ni, while stocks of organic C generally decreased. A principal component analysis showed that organic C content and base status mainly controlled soil microbial biomass and microbial respiration rates at these sites, while pH and mobile fractions of Cd, Cr, and Ni governed enzyme activities. Additionally,it was hypothesized that long-term fly ash emissions would eventually destabilize forest ecosystems. Therefore, the results of this study could become a useful tool for risk assessment in forest ecosystems that were subjected to past emissions from coal-fired power plants.

  19. Concentration of α-Linoleic Acid of Perilla Oil by Gradient Cooling Urea Inclusion

    Institute of Scientific and Technical Information of China (English)

    GU Hai-bo; MA Xue-yi; WU Jing-bo; ZHANG Qi; YUAN Wen-bing; CHEN Yi-ping

    2009-01-01

    In this study,production of α-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized.The fatty acid composition was determined after ethyl esterification by gas chromatography (GC).In this process,orthogonal experiment was carried out.Under optimum conditions,the maximum amount of α-linoleic acid (91.5%) was obtained at a urea to fatty acid ratio of 3,a solvent to fatty acids ratio of 7,a reaction temperature of 348 K and a crystallization time of 690 min.A simple method of gradient cooling urea inclusion was used to purify α-Iinolenie acid by using urea to form inclusion complexes with the saturated and the less unsaturated fatty acids,which enhanced the purity of α-iinoleic acid ethyl ester by above 90%.

  20. Soil Acidification due to Acid Deposition in Southern China

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Bohan

    1998-12-31

    Anthropogenic emission of SO{sub 2} and NO{sub x} to the atmosphere has made acid deposition one of the most serious environmental problems. In China, acid deposition research started in the late 1970s. The present thesis is part of a joint Chinese-Norwegian research project. The main goal of the thesis was to investigate the mechanism of soil acidification, to estimate soil responses to acid deposition, and to compare relative soil sensitivity to acidification in southern China. Laboratory experiments and modelling simulations were included. Specifically, the thesis (1) studies the characteristics of anion adsorption and cation release of the soils from southern China, (2) examines the effects of increased ionic strength in the precipitation and the effects of anion adsorption on cation release from the soils, (3) compares the relative sensitivity of these soils to acidification and the potentially harmful effects of acid deposition, (4) estimates likely soil responses to different deposition scenarios, including changes in soil waters and soil properties, and (5) investigates long-term changes in soils and soil waters in the Guiyang catchment due to acid deposition. 218 refs., 31 figs., 23 tabs.

  1. Nutrient stoichiometry in Sphagnum along a nitrogen deposition gradient in highly polluted region of Central-East Europe

    Energy Technology Data Exchange (ETDEWEB)

    Jirousek, Martin, E-mail: machozrut@mail.muni.c [Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlarska 2, 61137 Brno (Czech Republic); Hajek, Michal [Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlarska 2, 61137 Brno (Czech Republic); Bragazza, Luca [WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Site Lausanne, Station 2, Case Postale 96, CH-1015 Lausanne (Switzerland); Ecole Polytechnique Federale de Lausanne (EPFL), Laboratory of Ecological Systems - ECOS, Batiment GR, Station 2, CH-1015 Lausanne (Switzerland); Department of Biology and Evolution, University of Ferrara, Corso Ercole I d' Este 32, I-44100 Ferrara (Italy)

    2011-02-15

    We investigated the variation of N:P and N:K ratio in ombrotrophic Sphagnum plants along a gradient of atmospheric N deposition from 1 to 2.5 g m{sup -2} year{sup -1} in Central-East Europe. The N:P and N:K ratio in Sphagnum capitula increased significantly along the N deposition gradient. Sphagnum species from the Cuspidata section were characterised by significantly lower ratios at low N deposition. When we compared the observed N:P ratios in Sphagnum plants with the values reported in a previous European-wide study, we found a correspondence in nutrient stoichiometry only for a few bogs: higher P concentration in Sphagnum capitula caused a lower N:P ratio in most of the study bogs so that Sphagnum plants still seem N-limited despite their N saturation. Interaction between summer water table decrease and aerial liming of surrounding forests is proposed as an explanation for this discrepancy. Local forestry practice interacting with climate thus alter N:P stoichiometry of Sphagnum along the N deposition gradient. - Research highlights: Despite high atmopsheric nitrogen deposition, Sphagnum mosses still have rather low N:P ratio. Regional climate and landscape management can enhance P and K availability in bogs. Sphagnum species of the Cuspidata section were characterised by lower N:P ratio. - Regional climate and local forestry practices are expected to alter nutrient stoichiometry in Sphagnum mosses at high atmospheric N deposition in Central-East Europe.

  2. Membrane growth can generate a transmembrane pH gradient in fatty acid vesicles.

    Science.gov (United States)

    Chen, Irene A; Szostak, Jack W

    2004-05-25

    Electrochemical proton gradients are the basis of energy transduction in modern cells, and may have played important roles in even the earliest cell-like structures. We have investigated the conditions under which pH gradients are maintained across the membranes of fatty acid vesicles, a model of early cell membranes. We show that pH gradients across such membranes decay rapidly in the presence of alkali-metal cations, but can be maintained in the absence of permeable cations. Under such conditions, when fatty acid vesicles grow through the incorporation of additional fatty acid, a transmembrane pH gradient is spontaneously generated. The formation of this pH gradient captures some of the energy released during membrane growth, but also opposes and limits further membrane area increase. The coupling of membrane growth to energy storage could have provided a growth advantage to early cells, once the membrane composition had evolved to allow the maintenance of stable pH gradients.

  3. Effects of acid deposition on microbial processes in natural waters

    International Nuclear Information System (INIS)

    Biogeochemical processes mediated by microorganisms are not adversely affected by the acidification of natural waters to the same extent as are the life cycles of higher organisms. Basic processes, e.g., primary production and organic matter decomposition, are not slowed in moderately acidified systems and do not generally decline above a pH of 5. More specifically, the individual components of the carbon, nitrogen, and sulfur cycles are, with few exceptions, also acid resistant. The influence of acid deposition on microbial processes is more often stimulation of nitrogen and sulfur cycling, often leading to alkalinity production, which mitigates the effect of strong acid deposition. Bacterial sulfate reduction and denitrification in sediments are two of the major processes that can be stimulated by sulfate and nitrate deposition, respectively, and result in ANC (acid-neutralizing capacity) generation. One of the negative effects of acid deposition is increased mobilization and bioaccumulation of some metals. Bacteria appear to play an important role, especially in mercury cycling, with acidification leading to increased bacterial methylation of mercury and subsequent bioaccumulation in higher organisms

  4. Cooperative Effects in Aligned and Opposed Multicomponent Charge Gradients Containing Strongly Acidic, Weakly Acidic, and Basic Functional Groups.

    Science.gov (United States)

    Ashraf, Kayesh M; Giri, Dipak; Wynne, Kenneth J; Higgins, Daniel A; Collinson, Maryanne M

    2016-04-26

    Bifunctionalized surface charge gradients in which the individual component gradients either align with or oppose each other have been prepared. The multicomponent gradients contain strongly acidic, weakly acidic, and basic functionalities that cooperatively interact to define surface wettability, nanoparticle binding, and surface charge. The two-step process for gradient formation begins by modifying a siloxane coated silicon wafer in a spatially dependent fashion first with an aminoalkoxysilane and then with a mercapto-functionalized alkoxysilane. Immersion in hydrogen peroxide leads to oxidation of the surface immobilized sulfhydryl groups and subsequent protonation of the surface immobilized amines. Very different surface chemistries were obtained from gradients that either align with or oppose each other. X-ray photoelectron spectroscopy (XPS) data show that the degree of amine group protonation depends on the local concentration of sulfonate groups, which form ion pairs with the resulting ammonium ions. Contact angle measurements show that these ion pairs greatly enhance the wettability of the gradient surface. Finally, studies of colloidal gold binding show that the presence of both amine and thiol moieties enhance colloid binding, which is also influenced by surface charge. Cooperativity is also revealed in the distribution of charges on uniform samples used as models of the gradient surfaces, as evaluated via zeta potential measurements. Most significantly, the net surface charge and how it changes with distance and solution pH strongly depend on whether the gradients in amine and thiol align or oppose each other. The aligned multicomponent gradients show the most interesting behavior in that there appears to be a point at pH ∼ 6.5 where surface charge remains constant with distance. Setting the pH above or below this transition point leads to changes in the direction of charge variation along the length of the substrate. PMID:27073019

  5. Phenolic acids as bioindicators of fly ash deposit revegetation.

    Science.gov (United States)

    Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

    2006-05-01

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits. PMID:16418890

  6. Phenolic acids as bioindicators of fly ash deposit revegetation.

    Science.gov (United States)

    Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

    2006-05-01

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  7. Phenolic acids as bioindicators of fly ash deposit revegetation

    Energy Technology Data Exchange (ETDEWEB)

    L. Djurdjevic; M. Mitrovic; P. Pavlovic; G. Gajic; O. Kostic [Institute for Biological Research ' Sinisa Stankovic,' Belgrade (Serbia and Montenegro). Department of Ecology

    2006-05-15

    The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the 'Nikola Tesla-A' thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges. Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

  8. Electrophoretic deposition of tannic acid-polypyrrolidone films and composites.

    Science.gov (United States)

    Luo, Dan; Zhang, Tianshi; Zhitomirsky, Igor

    2016-05-01

    Thin films of polyvinylpyrrolidone (PVP)-tannic acid (TA) complexes were prepared by a conceptually new strategy, based on electrophoretic deposition (EPD). Proof of concept investigations involved the analysis of the deposition yield, FTIR and UV-vis spectroscopy of the deposited material, and electron microscopy studies. The analysis of the deposition mechanism indicated that the limitations of the EPD in the deposition of small phenolic molecules, such as TA, and electrically neutral polymers, similar to PVP, containing hydrogen-accepting carbonyl groups, can be avoided. The remarkable adsorption properties of TA and film forming properties of the PVP-TA complexes allowed for the EPD of materials of different types, such as huntite mineral platelets and hydrotalcite clay particles, TiO2 and MnO2 oxide nanoparticles, multiwalled carbon nanotubes, TiN and Pd nanoparticles. Moreover, PVP-TA complexes were used for the co-deposition of different materials and formation of composite films. In another approach, TA was used as a capping agent for the hydrothermal synthesis of ZnO nanorods, which were then deposited by EPD using PVP-TA complexes. The fundamental adsorption and interaction mechanisms of TA involved chelation of metal atoms on particle surfaces with galloyl groups, π-π interactions and hydrogen bonding. The films prepared by EPD can be used for various applications, utilizing functional properties of TA, PVP, inorganic and organic materials of different types and their composites. PMID:26878711

  9. Dramatic changes in ectomycorrhizal community composition, root tip abundance and mycelial production along a stand-scale nitrogen deposition gradient

    DEFF Research Database (Denmark)

    Kjøller, Rasmus; Nilsson, Lars Ola; Hansen, Karin;

    2012-01-01

    • Nitrogen (N) availability is known to influence ectomycorrhizal fungal components, such as fungal community composition, biomass of root tips and production of mycelia, but effects have never been demonstrated within the same forest. • We measured concurrently the abundance of ectomycorrhizal...... root tips and the production of external mycelia, and explored the changes in the ectomycorrhizal community composition, across a stand-scale N deposition gradient (from 27 to 43 kg N ha¿¹ yr¿¹) at the edge of a spruce forest. The N status was affected along the gradient as shown by a range of N...... availability indices. • Ectomycorrhizal root tip abundance and mycelial production decreased five and 10-fold, respectively, with increasing N deposition. In addition, the ectomycorrhizal fungal community changed and the species richness decreased. The changes were correlated with the measured indices of N...

  10. Electrophoretic deposition of silica-hyaluronic acid and titania-hyaluronic acid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ma, R. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7 (Canada); Zhitomirsky, I., E-mail: zhitom@mcmaster.ca [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7 (Canada)

    2011-06-15

    Research highlights: > The kinetics of electrodeposition of hyaluronic acid has been studied using quartz crystal microbalance. > Composite films containing silica and titania were prepared by electrophoretic deposition. > The deposition yield and deposit composition can be varied by variation of deposition time, voltage and bath composition. > We concluded that the method offers the advantages of room temperature processing for the fabrication of composite materials for biomedical applications. - Abstract: Thin films of hyaluronic acid were prepared by anodic electrophoretic deposition (EPD) and the deposition kinetics was studied using quartz crystal microbalance. EPD method has been developed for the fabrication of new ceramic-biopolymer nanocomposites containing silica and titania nanoparticles in the matrix of hyaluronic acid. The deposit thickness was varied in the range of 0-10 {mu}m. The composition of the deposits can be varied by the variation of silica and titania concentration in the suspensions. The deposits were studied by thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The method offers the advantages of room temperature processing of nanocomposite materials for biomedical applications.

  11. The cell transmembrane pH gradient in tumors enhances cytotoxicity of specific weak acid chemotherapeutics.

    Science.gov (United States)

    Kozin, S V; Shkarin, P; Gerweck, L E

    2001-06-15

    The extracellular pH is lower in tumor than in normal tissue, whereas their intracellular pH is similar. In this study, we show that the tumor-specific pH gradient may be exploited for the treatment of cancer by weak acid chemotherapeutics. i.v.-injected glucose substantially decreased the electrode estimated extracellular pH in a xenografted human tumor while its intracellular pH, evaluated by (31)P magnetic resonance spectroscopy, remained virtually unchanged. The resulting increase in the average cell pH gradient caused a parallel increase in tumor growth delay by the weak acid chlorambucil (CHL). Regardless of glucose administration, the effect of CHL was significantly greater in tumors preirradiated with a large dose of ionizing radiation. This suggests that CHL was especially pronounced in radioresistant hypoxic cells possessing a larger transmembrane pH gradient. These results indicate that the naturally occurring cell pH gradient difference between tumor and normal tissue is a major and exploitable determinant of the uptake of weak acids in the complex tumor microenvironment. The use of such drugs may be especially effective in combination with radiation.

  12. Floral gradient in flowering tobacco in relation to free amino acids

    Institute of Scientific and Technical Information of China (English)

    CHENYONGNING; WENANLI

    1993-01-01

    By employing TCLs (thin cell layers) culture, the floral gradient in flowering tobacco of different developmental stages was confirmed. The TCLs from early flowering tobacco regenerated more floral buds than those from the tobacco plants in full blooming or fruiting stages. Analysis of free amino acid levels revealed the acropetal gradient of Pro in flowering tobacco stem. L-Pro. L-Trp. D,L-Met and L-Arg were respectively added into the culture medium for testing their influence on floral bud formation from tobacco pedicel segments. Only L-Trp evidently enhanced the floral bud neoformation.

  13. Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols

    KAUST Repository

    Kravitz, Ben

    2009-07-28

    We used a general circulation model of Earth\\'s climate to conduct geoengineering experiments involving stratospheric injection of sulfur dioxide and analyzed the resulting deposition of sulfate. When sulfur dioxide is injected into the tropical or Arctic stratosphere, the main additional surface deposition of sulfate occurs in midlatitude bands, because of strong cross-tropopause flux in the jet stream regions. We used critical load studies to determine the effects of this increase in sulfate deposition on terrestrial ecosystems by assuming the upper limit of hydration of all sulfate aerosols into sulfuric acid. For annual injection of 5 Tg of SO2 into the tropical stratosphere or 3 Tg of SO2 into the Arctic stratosphere, neither the maximum point value of sulfate deposition of approximately 1.5 mEq m−2 a−1 nor the largest additional deposition that would result from geoengineering of approximately 0.05 mEq m−2 a−1 is enough to negatively impact most ecosystems.

  14. Base cation deposition in Europe - Part II. Acid neutralization capacity and contribution to forest nutrition

    NARCIS (Netherlands)

    Draaijers, G.P.J.; Leeuwen, E.P. van; Jong, P.G.H. de; Erisman, J.W.

    1997-01-01

    An assessment was made of the capacity of base cations to neutralize acid deposition and of the contribution of base cation deposition to forest nutrition in Europe. In large parts of southern Europe more than 50% of the potential acid deposition was found counteracted by deposition of non-sea salt

  15. ANALYSIS OF PHOSPHATE DEPOSIT “DISTURBANCES” USING THE HORIZONTAL-GRADIENT RESPONSES OF RESISTIVITY DATA (OULAD ABDOUN, MOROCCO

    Directory of Open Access Journals (Sweden)

    Bakkali Saad

    2005-08-01

    Full Text Available In the great Oulad Abdoun Basin exploitation of a new phosphate deposit was begun after the Grand Daoui horizon was exhausted. Inclusions of sterile hardpan-so-called "disturbances" -are hard to detect and interfere with phosphate extraction. Their resistivity is above 200 Ω.m as against 80 to 150 Ω.m for the phosphate-rich mineral. A Schlumberger resistivity survey over an area of 50 hectares was carried out. Models of the geology were successfully obtained from the analysis of the horizontal-gradient map of "disturbances". A new field procedure was tested to estimate the depth of disturbances. Phosphate reserves were better known.

  16. Design of step composition gradient thin film transistor channel layers grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Cheol Hyoun; Hee Kim, So; Gu Yun, Myeong; Koun Cho, Hyung, E-mail: chohk@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

    2014-12-01

    In this study, we proposed the artificially designed channel structure in oxide thin-film transistors (TFTs) called a “step-composition gradient channel.” We demonstrated Al step-composition gradient Al-Zn-O (AZO) channel structures consisting of three AZO layers with different Al contents. The effects of stacking sequence in the step-composition gradient channel on performance and electrical stability of bottom-gate TFT devices were investigated with two channels of inverse stacking order (ascending/descending step-composition). The TFT with ascending step-composition channel structure (5 → 10 → 14 at. % Al composition) showed relatively negative threshold voltage (−3.7 V) and good instability characteristics with a reduced threshold voltage shift (Δ 1.4 V), which was related to the alignment of the conduction band off-set within the channel layer depending on the Al contents. Finally, the reduced Al composition in the initial layer of ascending step-composition channel resulted in the best field effect mobility of 4.5 cm{sup 2}/V s. We presented a unique active layer of the “step-composition gradient channel” in the oxide TFTs and explained the mechanism of adequate channel design.

  17. Nutrient availability and phytoplankton nutrient limitation across a gradient of atmospheric nitrogen deposition

    Science.gov (United States)

    Elser, J.J.; Kyle, M.; Steuer, L.; Nydick, K.R.; Baron, J.S.

    2009-01-01

    Atmospheric nitrogen (N) deposition to lakes and watersheds has been increasing steadily due to various anthropogenic activities. Because such anthropogenic N is widely distributed, even lakes relatively removed from direct human disturbance are potentially impacted. However, the effects of increased atmospheric N deposition on lakes are not well documented, We examined phytoplankton biomass, the absolute and relative abundance of limiting nutrients (N and phosphorus [P]), and phytoplankton nutrient limitation in alpine lakes of the Rocky Mountains of Colorado (USA) receiving elevated (>6 kg N??ha-1??yr-1) or low (atmospheric N deposition. Highdeposition lakes had higher NO3-N and total N concentrations and higher total N : total P ratios. Concentrations of chlorophyll and seston carbon (C) were 2-2.5 times higher in highdeposition relative to low-deposition lakes, while high-deposition lakes also had higher seston C:N and C:P (but not N:P) ratios. Short-term enrichment bioassays indicated a qualitative shift in the nature of phytoplankton nutrient limitation due to N deposition, as highdeposition lakes had an increased frequency of primary P limitation and a decreased frequency and magnitude of response to N and to combined N and P enrichment. Thus elevated atmospheric N deposition appears to have shifted nutrient supply from a relatively balanced but predominantly N-deficient regime to a more consistently P-limited regime in Colorado alpine lakes. This adds to accumulating evidence that sustained N deposition may have important effects on lake phytoplankton communities and plankton-based food webs by shifting the quantitative and qualitative nature of nutrient limitation. ?? 2009 by the Ecological Society of America.

  18. Regional scale gradients of climate and nitrogen deposition drive variation in ectomycorrhizal fungal communities associated with native Scots pine.

    Science.gov (United States)

    Jarvis, S; Woodward, S; Alexander, I J; Taylor, A F S

    2013-06-01

    Ectomycorrhizal fungi commonly associate with the roots of forest trees where they enhance nutrient and water uptake, promote seedling establishment and have an important role in forest nutrient cycling. Predicting the response of ectomycorrhizal fungi to environmental change is an important step to maintaining forest productivity in the future. These predictions are currently limited by an incomplete understanding of the relative significance of environmental drivers in determining the community composition of ectomycorrhizal (ECM) fungi at large spatial scales. To identify patterns of community composition in ECM fungi along regional scale gradients of climate and nitrogen deposition in Scotland, fungal communities were analysed from 15 seminatural Scots pine (Pinus sylvestris L.) forests. Fungal taxa were identified by sequencing of the ITS rDNA region using fungal-specific primers. Nonmetric multidimensional scaling was used to assess the significance of 16 climatic, pollutant and edaphic variables on community composition. Vector fitting showed that there was a strong influence of rainfall and soil moisture on community composition at the species level, and a smaller impact of temperature on the abundance of ectomycorrhizal exploration types. Nitrogen deposition was also found to be important in determining community composition, but only when the forest experiencing the highest deposition (9.8 kg N ha(-1)  yr(-1) ) was included in the analysis. This finding supports previously published critical load estimates for ectomycorrhizal fungi of 5-10 kg N ha(-1)  yr(-1) . This work demonstrates that both climate and nitrogen deposition can drive gradients of fungal community composition at a regional scale. PMID:23505218

  19. Fractionating vacuum thermal deposition of polyaniline films. Effect of post-deposition acid-base treatment

    Energy Technology Data Exchange (ETDEWEB)

    Nekrasov, A.A. (Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Leninskii Prospect 31, Moscow 117071 (Russian Federation)); Ivanov, V.F. (Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Leninskii Prospect 31, Moscow 117071 (Russian Federation)); Gribkova, O.L. (Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Leninskii Prospect 31, Moscow 117071 (Russian Federation)); Vannikov, A.V. (Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Leninskii Prospect 31, Moscow 117071 (Russian Federation))

    1994-07-15

    Vacuum thermal evaporation of a single portion of chemically synthesized polyaniline (PAN) base powder was performed step-by-step within four temperature intervals in the 240-450 C range. The vapour was deposited on quartz and SnO[sub 2]-glass substrates, each fraction being deposited on a separate substrate. The samples obtained were subjected to cyclic contrast acid-base treatment, and UV-Vis spectra of the fractions after each treatment cycle were registered. The spectra of the as-deposited fractions appear to have little in common with conventional PAN spectra. The appearance of absorption bands essential for conventional PAN spectra is found to occur for some of the fractions only after the above treatment. This is apparently due to recombination of PAN oligomer radical fragments, formed in the course of the evaporation, resulting in restoration of PAN macromolecule structure. The recombination may be intensified by conformational changes during the acid-base treatment. Cyclic voltammetry curves for the most PAN-like fractions resemble the ones for conventional PAN. ((orig.))

  20. Englemann spruce nitrogen dynamics across a nitrogen deposition gradient in Colorado, USA

    Science.gov (United States)

    Rueth, H.M.; Baron, J.S.

    2001-01-01

    We asked whether nitrogen (N) deposition has altered Englemann spruce (Picea englemannii) biogeochemistry along the east side of the Colorado Front Range, USA. Twelve similar old-growth Englemann spruce stands were sampled, six with low (1-2 kg N ha-1 yr-1) and six with higher (3-5 kg N ha-1 yr-1) N deposition inputs. Species composition, elevation, aspect, parent material, site history and climate were matched as closely as possible across all sites. High N deposition sites had significantly lower organic horizon C:N and lignin:N ratios, and foliar lignin:N and C:N ratios, as well as greater %N and N:Mg ratios, and potential net mineralization rates. The relationship between organic horizon %N and potential net mineralization rates suggests a threshold of 1.2% N, above which mineralization increases linearly. Studies in the Northeastern US and Europe have found changes in forest biogeochemistry in response to nitrogen (N) deposition inputs between 3-60 kg N ha-1 yr-1. Our results suggest that current levels of N deposition (3-5 kg N ha-1 yr-1) along the Colorado Front Range may be altering Englemann spruce biogeochemistry. The results indicate even relatively low N inputs may cause measurable changes in forest biogeochemistry.

  1. Post-depositional migration and preservation of methanesulfonic acid (MSA) in polar ice cores

    Science.gov (United States)

    Osman, M.; Marchal, O.; Guo, W.; Das, S. B.; Evans, M. J.

    2015-12-01

    Methanesulfonic acid (MSA; CH3SO3-) in ice cores is a unique, high-resolution proxy of regional sea ice behavior, marine primary productivity, and synoptic climatology. Significant uncertainties remain, however, in both our understanding of the production and transfer of MSA to the ice sheet, as well as its preservation over time, compromising the paleoclimatological utility of the proxy. Here we apply a numerical modeling approach to quantitatively investigate the post-depositional processes affecting MSA migration and preservation within the firn and ice column, building on recent observational and theoretical studies. Our model allows us to evaluate the timing and magnitude of the vertical movement of MSA in response to varying influences, including the competing effects of 1) concentration gradients of sea-salts typically deposited asynchronously to MSA, 2) snow accumulation and densification rates, and 3) in situ temperature gradients. We first test the model against a recently collected ice core from a high accumulation site in coastal West Antarctica, where monthly-resolved MSA records show an abrupt shift from a summer-to-winter maximum in MSA at ~23m depth (ρ ≈ 650 kg/m3), near the firn-ice transition. We find our model to be a robust predictor of the observed migrational features in this record, capturing both (i) the abrupt shift in summer-to-winter maximal concentrations of MSA (steady state ≈ 3.2 yrs), and (ii) the depression of the seasonal amplitude at depth. Further, our modeling results suggest post-depositional effects can lead to substantial interannual alteration of the MSA signal, contrary to previous assumptions that MSA migration is confined within annual layers at high accumulation sites. Using a broad range of polar MSA records and their associated, site-specific environmental conditions, we will evaluate the fidelity of subannual to interannual variability of MSA records and systematically determine the factors conducive to its

  2. Anacardic acid-mediated changes in membrane potential and pH gradient across liposomal membranes.

    Science.gov (United States)

    Toyomizu, Masaaki; Okamoto, Katsuyuki; Akiba, Yukio; Nakatsu, Tetsuo; Konishi, Tetsuya

    2002-01-01

    We have previously shown that anacardic acid has an uncoupling effect on oxidative phosphorylation in rat liver mitochondria using succinate as a substrate (Life Sci. 66 (2000) 229-234). In the present study, for clarification of the physicochemical characteristics of anacardic acid, we used a cyanine dye (DiS-C3(5)) and 9-aminoacridine (9-AA) to determine changes of membrane potential (DeltaPsi) and pH difference (DeltapH), respectively, in a liposome suspension in response to the addition of anacardic acid to the suspension. The anacardic acid quenched DiS-C3(5) fluorescence at concentrations higher than 300 nM, with the degree of quenching being dependent on the log concentration of the acid. Furthermore, the K(+) diffusion potential generated by the addition of valinomycin to the suspension decreased for each increase in anacardic acid concentration used over 300 nM, but the sum of the anacardic acid- and valinomycin-mediated quenching was additively increasing. This indicates that the anacardic acid-mediated quenching was not due simply to increments in the K(+) permeability of the membrane. Addition of anacardic acid in the micromolar range to the liposomes with DeltaPsi formed by valinomycin-K(+) did not significantly alter 9-AA fluorescence, but unexpectedly dissipated DeltaPsi. The DeltaPsi preformed by valinomycin-K(+) decreased gradually following the addition of increasing concentrations of anacardic acid. The DeltaPsi dissipation rate was dependent on the pre-existing magnitude of DeltaPsi, and was correlated with the logarithmic concentration of anacardic acid. Furthermore, the initial rate of DeltapH dissipation increased with logarithmic increases in anacardic acid concentration. These results provide the evidence for a unique function of anacardic acid, dissimilar to carbonylcyanide p-trifluoromethoxyphenylhydrazone or valinomycin, in that anacardic acid behaves as both an electrogenic (negative) charge carrier driven by DeltaPsi, and a 'proton

  3. Simulation of soil response to acidic deposition scenarios in Europe

    International Nuclear Information System (INIS)

    The chemical response of European forest soils to three emission-deposition scenarios for the year 1960-2050, i.e. official energy pathways (OEP), current reduction plans (CRP) and maximum feasible reductions (MFR), was evaluated with the SMART model (Simulation Model for Acidification's Regional Trends). Calculations were made for coniferous and deciduous forests on 80 soil types occurring on the FAO soil map of Europe, using a gradient of 1.0 degree C longitude x 0.5 degree latitude. Results indicated that the area with nitrogen saturated soils, i.e. soils with elevated NO3 concentrations (>0.02 molcm-3) will increase in the future for all scenarios, even for the MFR scenario. The area with acidified soils, with a high Al concentration (> 0.2 molcm-3) and Al/BC ratio (>1 mol-1) and a low pH (3 and Al concentrations mainly occurred in western, central and eastern Europe. Uncertainties in the initial values of C/N ratios and base saturation, and in the description of N dynamics in the SMART model had the largest impact on the temporal development of forested areas exceeding critical parameter values. Despite uncertainties involved, predicted general trends are plausible and reliable. 61 refs., 11 figs., 10 tabs

  4. Microbiology of Low Temperature Seafloor Deposits Along a Geochemical Gradient in Lau Basin

    Science.gov (United States)

    sylvan, J. B.; Sia, T. Y.; Haddad, A.; Briscoe, L. J.; Girguis, P. R.; Edwards, K. J.

    2011-12-01

    The East Lau Spreading Center (ELSC) and Valu Fa Ridge comprise a ridge segment in the southwest Pacific Ocean where rapid transitions in the underlying mantle lenses manifest themselves by gradients in seafloor rock geochemistry. At the spreading center in the north, basaltic host rock extrudes while the influence of subduction in the south creates mainly basaltic andesite host rock. A contuous gradient between these two end members exists along the spreading center. We studied the geology and microbial diversity of three silicate rock samples and three inactive sulfide chimney samples collected along the ELSC and Valu Fa Ridge by X-ray diffraction, elemental analysis, thin section analysis and construction of bacterial 16S rRNA clone libraries. Here, we discuss the geological and biological differences between the collected rocks. We found that the bacterial community composition changed as the host rock mineralogy and chemistry changed from north to south. Also, the bacterial community composition on the silicates is distinct from those on the inactive chimneys, and the interior conduit of an inactive chimney hosts a very different community from the exterior. Basalt from the northern end of the ELSC had high proportions of Alphaproteobacteria and Bacteroidetes. These proportions decreased on the silicates collected further south. Epsilonproteobacteria were also present on the basalt, decreased further south and were absent on the basaltic andesite. Conversely, basaltic andesite rocks from the southern end had high proportions of Chloroflexi, which decreased further north and were absent on basalt. The exterior of inactive sulfide structures were dominated by lineages of sulfur oxidizing Gammaproteobacteria and Epsilonproteobacteria and were less diverse than those on the silicates. The interior of one chimney was dominated by sulfate-reducing Deltaproteobacteria and was the least diverse of all samples. These results support the Mantle to Microbe hypothesis in

  5. Gradient titanium and silver based carbon coatings deposited on AISI316L

    Science.gov (United States)

    Batory, Damian; Reczulska, Malgorzata Czerniak-; Kolodziejczyk, Lukasz; Szymanski, Witold

    2013-06-01

    The constantly growing market for medical implants and devices caused mainly due to a lack of proper attention attached to the physical condition as well as extreme sports and increased elderly population creates the need of new biocompatible biomaterials with controlled bioactivity and certain useful properties. According to many literature reports, regarding the modifications of variety of different biomaterials using the surface engineering techniques and their biological and physicochemical examination results, the most promising material for great spectra of medical applications seem to be carbon layers. Another issue is the interaction between the implant material and surrounding tissue. In particular cases this interface area is directly exposed to air. Abovementioned concern occurs mainly in case of the external fixations, thus they are more vulnerable to infection. Therefore a crucial role has the inhibition of bacterial adhesion that may prevent implant-associated infections, occurrence of other numerous complications and in particular cases rejection of the implant. For this reason additional features of carbon coatings like antibacterial properties seem to be desired and justified. Silver doped diamond-like carbon coatings with different Ag concentrations were prepared by hybrid RF PACVD/MS (Radio Frequency Plasma Assisted Chemical Vapor Deposition/Magnetron Sputtering) deposition technique. Physicochemical parameters like chemical composition, morphology and surface topography, hardness and adhesion were determined. Examined layers showed a uniform distribution of silver in the amorphous DLC matrix, high value of H/E ratio, good adhesion and beneficial topography which make them a perfect material for medical applications e.g. modification of implants for the external fixations.

  6. Acidic polyanion poly(acrylic acid) prevents calcium oxalate crystal deposition

    OpenAIRE

    Kleinman, Jack G.; Alatalo, Laura J.; Beshensky, Ann M.; Wesson, Jeffrey A.

    2008-01-01

    Acidic macromolecules inhibit calcium oxalate nucleation, growth, aggregation and attachment to cells in vitro. To test for such an effect in vivo we used osmotic minipumps to continuously infuse several doses of the 5.1 kDa poly(acrylic acid) (pAA5.1) into rats fed a diet which causes renal calcium oxalate crystal deposition. Although kidneys of rats receiving the saline control contained calcium oxalate crystals, measured by polarized light microscopy, those of animals given pAA5.1 had sign...

  7. Rhizosphere bacterial communities of dominant steppe plants shift in response to a gradient of simulated nitrogen deposition

    Directory of Open Access Journals (Sweden)

    An eYang

    2015-08-01

    Full Text Available We evaluated effects of 9-year simulation of simulated nitrogen (N deposition on microbial composition and diversity in the rhizosphere of two dominant temperate grassland species: grass Stipa krylovii and forb Artemisia frigida. Microbiomes in S. krylovii and A.frigida rhizosphere differed, but changed consistently along the N gradient. These changes were correlated to N-induced shifts to plant community. Hence, as plant biomass changed, so did bacterial rhizosphere communities, a result consistent with the role that N fertilizer has been shown to play in altering plant-microbial mutualisms. A total of 23 bacterial phyla were detected in the two rhizospheric soils by pyrosequencing, with Proteobacteria, Acidobacteria and Bacteroidetes dominating the sequences of all samples. Bacterioidetes and Proteobacteria tended to increase, while Acidobacteria declined with increase in N addition rates. TM7 increased >5-fold in the high N addition rates, especially in S. krylovii rhizosphere. Nitrogen addition also decreased diversity of OTUs (operational taxonomic units, Shannon and Chao1 indices of rhizospheric microbes regardless of plant species. These results suggest that there were both similar but also specific changes in microbial communities of temperate steppes due to N deposition.

  8. Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions.

    Science.gov (United States)

    Yao, Fang-Fang; Ding, Hui-Ming; Feng, Li-Li; Chen, Jing-Jing; Yang, Song-Yu; Wang, Xi-Hua

    2016-05-01

    A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability. PMID:26797956

  9. TiN+gradient or multi(Ti,Al,Si)N+TiN coatings deposited on cermets by CAE process: characteristic of structure and properties

    OpenAIRE

    L.A. Dobrzański; K. Gołombek

    2005-01-01

    Purpose: It has been demonstrated in the paper that deposition of the multilayer and gradient coatings with the PVD method in the Cathodic Arc Evaporation CAE process on tools made from cermets.Design/methodology/approach: Structural examinations are presented of the applied coatings and their substrate made on the TEM, SEM and on the light microscope. Evaluation of the adhesion of the deposited coatings onto the cermets was made using the scratch test. Cutting properties of the investigated ...

  10. Effects of acid deposition on terrestrial ecosystems and their rehabilitation strategies in China

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    South China has become the third largest region associated with acid deposition following Europe and North America, the area subject to damage by acid deposition increased from 1.75 million km2 in 1985 to 2.8 million km2 in 1993. Acid deposition has caused serious damage to ecosystem. Combined pollution of acid rain and SO2 showed the obvious multiple effects on crops. Vegetable was more sensitive to acid deposition than foodstuff crops. Annual economic loss of crops due to acid deposition damage in eleven provinces of south China was 4.26billion RMB Yuan. Acid deposition caused serious damage to forest. Annual economic loss of wood volume was about 1.8 billion RMB Yuan management, specifying acid-controlling region, controlling and abating the total emission amount of SO2; (2) selecting practical energy technologies of clean coal, for example, cleansing and selecting coal, sulfur-fixed-type industrial briqutting, abating sulfur from waste gas and so on; (3) developing other energy sources to replace coal, including water electricity, atomic energy and the new energy such as solar energy,wind energy and so on; (4) in acid deposition region of south China, selecting acid-resistant tvpe of crop and tree to decrease agricultural losses, planting more green fertilizer crops, using organic fertilizers and liming, in order to improve buffer capacities of soil.

  11. [Determination of organic acids and inorganic anions by gradient ion chromatography].

    Science.gov (United States)

    Liu, Z; Liu, K; Shen, D; Song, Q; Mou, S; Feng, Y

    1997-07-01

    The chromatographic conditions for separation and detection of organic acids and inorganic anions by gradient ion chromatography with suppressed conductivity detection were studied. The optimized gradient programs were established. Ion chromatography were performed with a DX-100 chromatograph (DIONEX). The separation column is IonPac-AS11. Compared with NaHCO3/Na2CO3 and Na2B4O7, NaOH was the optimal eluent. The effect of organic modifier was also studied. Among methanol, 2-propanol and acetonitrile, methanol can make ion pairs such as malate and succinate, malonate and tartrate gaining baseline resolution. By using ion exchange separation, Cl-, NO3-, malate, succinate, malonate, tartrate, SO4(2-), oxalate were eluted between 5 mmol/L NaOH-16% CH3OH and 10 mmol/L NaOH-16% CH3OH in 25 min. A mobile phase composed of 30 mmol/L NaOH, 50% CH3OH and D.I. water was chosen to elute two groups of organic acids and inorganic anions: (1) quinate, formate, Cl-, malate, malonate, oxalate, citrate, isocitrate, aconitate; (2) lactate, Cl-, SO4(2-), tartrate, PO4(3-), citrate, isocitrate, aconitate. The detection limits (S/N = 3) were 0.1625 (quinate), 0.0691 (formate), 0.0115 (Cl-), 0.0886 (malate), 0.0591 (malonate), 0.0263 (oxalate), 0.1147 (citrate), 0.2017 (isocitrate), 0.3656 (cis-aconitate), 0.1045 (trans-aconitate), 0.1950 (lactate), 0.0729 (tartrate), 0.0224 (SO4(2-)) and 0.0692 (PO4(3-)) mg/L. The relative standard deviations were lower than 11.9% (n = 7) and the correlation coefficients ranged from 0.9212 for Cl- to 0.9999 for formate. The method was applied to determine the organic acids and inorganic anions of beverages and citric acids fermenting-medium. The results were satisfactory.

  12. Acidic deposition and its effects in southwestern China

    International Nuclear Information System (INIS)

    The emissions of SO2 in China correspond at present to 8-10 TgSy-1. The rapid industrialization has caused a dramatic increase in the emissions in recent years and this increase is likely to continue. This paper describes studies of concentrations and effects of acidifying substances in parts of the Guizhou and the Sichuan provinces where the S-emissions are large, mainly coming from coal combustion. A small catchment about 10 km from Guiyang centre was equipped with instruments for studies of soils, soil water and streamwater chemistry. The molar ratio Al/(Ca + Mg) is > 0.8 in soil water in some places. Two small streams have median pH-values about 4.6 and 5.1. Laboratory studies with selected Chinese soils showed that the anion adsorption was low. These studies gave also important information on soil sensitivity. The studies confirm that acid deposition may affect soils in parts of south-western China, but the sensitivity varies dramatically and there is a strong need for more information. 11 refs., 3 tabs., 3 figs

  13. Comparison of the PVD gradient coatings deposited onto X40CrMoV5-1 and HS6-5-2 tool steel substrate

    OpenAIRE

    K. Lukaszkowicz; L.A. Dobrzański; M. Staszuk; M. Pancielejko

    2008-01-01

    Purpose: The main aim of this research was investigation and comparison of selected properties of gradient coatings TiCN and AlSiCrN. In this paper both coatings were deposited by cathode arc evaporation physical vapour deposition (CAE-PVD) method onto high speed steel HS6-5-2 and hot work tool steel X40CrMoV5-1.Design/methodology/approach: Observations of surface and structures of the deposited coatings were carried out on cross sections in the scanning electron microscope. The phase composi...

  14. CA2+-INDUCED FUSION OF PHOSPHOLIPID-VESICLES CONTAINING FREE FATTY-ACIDS - MODULATION BY TRANSMEMBRANE PH GRADIENTS

    NARCIS (Netherlands)

    WILSCHUT, J; SCHOLMA, J; EASTMAN, SJ; HOPE, MJ; CULLIS, PR

    1992-01-01

    The influence of a transmembrane pH gradient on the Ca2+-induced fusion of phospholipid vesicles, containing free fatty acids, has been investigated. Large unilamellar vesicles composed of an equimolar mixture of cardiolipin, dioleoylphosphatidylcholine, and cholesterol, containing 20 mol % oleic ac

  15. Effect of dietary fat sources on fatty acid deposition and lipid metabolism in broiler chickens

    NARCIS (Netherlands)

    Smink, W.; Gerrits, W.J.J.; Hovenier, R.; Geelen, M.J.H.; Verstegen, M.W.A.; Beynen, A.C.

    2010-01-01

    The hypothesis tested was that dietary vegetable fats rich in saturated fatty acids, when compared with a vegetable oil rich in linoleic acid, increase fat deposition in broiler chickens and affect synthesis or oxidation, or both, of individual fatty acids. Diets with native sunflower oil (SO), a 50

  16. Naphthenic acid extraction and characterization from crude oils and naphthenate field deposits revisited

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.M.; Sorbie, K.S. [Heriot-Watt Univ., Edinburgh, Scotland (United Kingdom). Inst. of Petroleum Engineering

    2008-07-01

    Crude oil with high total acid number (TAN) often results in the formation of either sodium emulsion or calcium naphthenate deposits. The formation of calcium naphthenate during production operations is creating flow assurance problems for the oil industry. Therefore, it is important to extract and characterize the different types of acids from crude oils and naphthenate field deposits. There has been much discussion in the literature about the discovery and quantification of higher molecular weight acids in naphthenate field deposits, referred to as ARN acids. Field naphthenate deposits from 2 different fields in Norway (X and HD) were used in this study for the naphthenic acid extraction using 3 different methods. The extracted naphthenic acids were characterized using electrospray mass spectrometry (ESMS) and atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The ESMS spectra obtained from field X extract revealed the presence of lower molecular weight acids species only, without any presence of ARN acids. However, the extract from field HD had a broad range of lower molecular weight acids and ARN acid species. APCI-MS results revealed an enhanced ARN acids species from all the spectra with some indication of multimers. This paper also discussed the acid-IER extraction technique used on the crude oils from these fields.

  17. Effects of decreasing acid deposition and climate change on acid extremes in an upland stream

    Directory of Open Access Journals (Sweden)

    C. D. Evans

    2008-03-01

    Full Text Available This study assesses the major chemical processes leading to acid extremes in a small, moorland stream in mid-Wales, UK, which has been monitored since 1979. Results suggest that base cation (mainly calcium dilution, the "sea-salt effect", and elevated nitrate pulses, are the major causes of seasonal/episodic minima in acid neutralising capacity (ANC, and that the relative importance of these drivers has remained approximately constant during 25 years of decreasing acid deposition and associated long-term chemical recovery. Many of the chemical variations causing short-term reductions in stream acidity, particularly base cation dilution and organic acid increases, are closely related to changes in water-flowpath and therefore to stream discharge. Changes in the observed pH-discharge relationship over time indicate that high-flow pH has increased more rapidly than mean-flow pH, and therefore that episodes have decreased in magnitude since 1980. However a two-box application of the dynamic model MAGIC, whilst reproducing this trend, suggests that it will not persist in the long term, with mean ANC continuing to increase until 2100, but the ANC of the upper soil (the source of relatively acid water during high-flow episodes stabilising close to zero beyond 2030. With climate change predicted to lead to an increase in maximum flows in the latter half of the century, high-flow related acid episodes may actually become more rather than less severe in the long term, although the model suggests that this effect may be small. Two other predicted climatic changes could also detrimentally impact on acid episodes: increased severity of winter "sea-salt" episodes due to higher wind speeds during winter storms; and larger sulphate pulses due to oxidation of reduced sulphur held in organic soils, during more extreme summer droughts. At the Gwy, the near-coastal location and relatively small extent of peat soils suggest that sea-salt episodes may have the

  18. Microbial ecology of á-Proteobacteria ammonia-oxidizers along a concentration gradient of dry atmospheric nitrogen deposition in the San Bernadino Mountain Range.

    Science.gov (United States)

    Jordan, F. L.; Fenn, M. E.; Stein, L. Y.

    2002-12-01

    The fate of atmospherically-deposited nitrogen from industrial pollution is of major concern in the montane ecosystems bordering the South Coast California Air Basin. Nitrogen deposition rates in the more exposed regions of the San Bernardino Mountains (SBM) are among the highest in North America often exceeding 40 kg ha-1 year-1 in throughfall deposition of nitrate and ammonium (Fenn and Poth, 1999). Forest ecosystems with elevated N deposition generally exhibit elevated accumulation of soil nitrate, leaching and runoff, elevated emissions of nitrogenous gases, increased nitrification, and decreased litter decomposition rates. The role of nitrifying microbial populations, especially those taxonomically associated with the beta-Proteobacteria ammonia-oxidizers (AOB), will provide insight into nitrogen-cycling in these extremely N-saturated environments. Using 16S ribosomal DNA-based molecular techniques (16S rDNA clone library construction and Restriction Fragment Length Polymorphism), we are comparing AOB community diversity at 3 different locations along a natural atmospheric N-deposition concentration gradient in the SBM: from high at Camp Paviaka (CP), medium at Strawberry Peak (SP) to low at Dogwood (DW). As observed for wet N-deposition systems on the east coast, we hypothesized a negative correlation between AOB community diversity, abundance and function with nitrogen loading in the dry N deposition system of SBM. Nitrification potentials determined for the 3 sites along the N-deposition gradient were in the order of CP less than SP less than DW. Preliminary results indicate no correlation between diversity of AOB and increased nitrogen loading. Shannon-Weiner diversity indices calculated for ammonia-oxidizer RFLP group units were 2.22, 2.66 and 1.80 for CP, SP and DW, respectively.

  19. The solubility of aluminum in acidic forest soils: Long-term changes due to acid deposition

    Science.gov (United States)

    Mulder, Jan; Stein, Alfred

    1994-01-01

    Despite the ecological and pedogenic importance of Al, its solubility control in acidic forest soils is poorly understood. Here we discuss the solubility of Al and its development with time in three acid brown forest soils in The Netherlands, which are under extreme acidification from atmospheric deposition. All soil solutions (to a 60 cm depth) were undersaturated with respect to synthetic gibbsite (Al(OH) 3; log K = 9.12 at 8°C), with the highest degree of undersaturation occurring in the surface soil. In about one third of the individual soil layers a significant positive correlation existed between the activity of Al 3+ and H +, but this relationship was far less than cubic. Kinetically constrained dissolution of Al is unlikely to explain the disequilibrium with respect to gibbsite, because undersaturation was highest through summer when water residence times were longest and temperatures greatest. Time series analysis of six year data sets for several soil layers revealed a significant annual decline in soil solution pH and Al solubility (defined as log Al + 3 pH) despite a constant concentration of strong acid anions. The annual decline of both pH and Al solubility was greatest in the surface soil and was positively correlated with the relative depletion of reactive organically bound soil Al. The results support our earlier hypothesis that in strongly acidified forest soils complexation by solid phase organics controls the solubility of Al even in mineral soil layers, relatively low in organic C. The data lend no support to the current widespread and often uncritical use of gibbsite as a model for the Al solubility in highly acidic forest soils (pH temperate zone.

  20. Dietary conjugated linoleic acids increase intramuscular fat deposition and decrease subcutaneous fat deposition in Yellow Breed × Simmental cattle.

    Science.gov (United States)

    Zhang, Haibo; Dong, Xianwen; Wang, Zhisheng; Zhou, Aiming; Peng, Quanhui; Zou, Huawei; Xue, Bai; Wang, Lizhi

    2016-04-01

    This study was conducted to estimate the effect of dietary conjugated linoleic acids (CLA) on intramuscular and subcutaneous fat deposition in Yellow Breed × Simmental cattle. The experiment was conducted for 60 days. The results showed that the average backfat thickness, (testicles + kidney + pelvic) fat percentage and subcutaneous fat percentage in dietary CLA were significantly lower than in the control group, while intramuscular the fat percentage was significantly higher. Compared to the control group, the Longissimus muscle enzyme activities of lipoprotein lipase (LPL), fatty acid synthase (FAS) and acetyl-coenzyme A carboxylase (ACC) in dietary CLA and the subcutaneous fat enzyme activities of LPL, hormone-sensitive lipase (HSL) and carnitine palmitoyltransferase-1 (CPT-1) were significantly increased. Similarly, compared to the control group, the Longissimus muscle sterol regulatory element binding protein 1 (SREBP-1), FAS, stearoyl-coenzyme A desaturase (SCD), ACC, peroxisome proliferator-activated receptor γ (PPARγ), heart fatty-acid binding protein (H-FABP) and LPL gene expression in dietary CLA were significant increased, as were the subcutaneous fat of PPARγ, H-FABP, LPL, CPT-1 and HSL in dietary CLA. These results indicated that dietary CLA increases IMF deposition mainly by the up-regulation of lipogenic gene expression, while decreasing subcutaneous fat deposition mainly by the up-regulation of lipolytic gene expression. PMID:26582037

  1. Influence of containing of asphaltenes and naphthenic acids over organic deposition inhibitor performance

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Geiza E.; Mansur, Claudia R.E.; Pires, Renata V.; Passos, Leonardo B.; Lucas, Elizabete F. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas; Alvares, Dellyo R.S.; Gonzalez, Gaspar [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2004-07-01

    Organic deposition is a serious problem confronted by the petroleum industry in Brazil and worldwide. Among the main petroleum components that may cause deposition problems are waxes and asphaltenes. This work aims at evaluating the influence of petroleum fractions (asphaltenes and naphthenic acids) on the organic deposition phenomenon as well as on organic deposition inhibitors performance. The influence of the organic fractions was evaluated by their ability to change wax crystals, to lower the pour point and to alter the initial wax appearance temperature. The efficiency of the additives was tested by pour point measurements. The results show that asphaltenes seem to act as organic deposition inhibitors, while naphthenic acids do not significantly change the system. Moreover, employing both of them produces no synergic effect. Among polymeric inhibitors, all of the chemically modified EVA copolymer presented better results than the non-modified commercial EVA copolymer. The best result was observed for EVA28C{sub 16}. (author)

  2. Fatty Acid-Oxidizing Consortia along a Nutrient Gradient in the Florida Everglades†

    OpenAIRE

    Chauhan, Ashvini; Ogram, Andrew

    2006-01-01

    The Florida Everglades is one of the largest freshwater marshes in North America and has been subject to eutrophication for decades. A gradient in P concentrations extends for several kilometers into the interior of the northern regions of the marsh, and the structure and function of soil microbial communities vary along the gradient. In this study, stable isotope probing was employed to investigate the fate of carbon from the fermentation products propionate and butyrate in soils from three ...

  3. A new look at liming as an approach to accelerate recovery from acidic deposition effects

    Science.gov (United States)

    Lawrence, Gregory B.; Burns, Douglas A.; Murray, Karen

    2016-01-01

    Acidic deposition caused by fossil fuel combustion has degraded aquatic and terrestrial ecosystems in North America for over four decades. The only management option other than emissions reductions for combating the effects of acidic deposition has been the application of lime to neutralize acidity after it has been deposited on the landscape. For this reason, liming has been a part of acid rain science from the beginning. However, continued declines in acidic deposition have led to partial recovery of surface water chemistry, and the start of soil recovery. Liming is therefore no longer needed to prevent further damage, so the question becomes whether liming would be useful for accelerating recovery of systems where improvement has lagged. As more is learned about recovering ecosystems, it has become clear that recovery rates vary with watershed characteristics and among ecosystem components. Lakes appear to show the strongest recovery, but recovery in streams is sluggish and recovery of soils appears to be in the early stages. The method in which lime is applied is therefore critical in achieving the goal of accelerated recovery. Application of lime to a watershed provides the advantage of increasing Ca availability and reducing or preventing mobilization of toxic Al, an outcome that is beneficial to both terrestrial and aquatic ecosystems. However, the goal should not be complete neutralization of soil acidity, which is naturally produced. Liming of naturally acidic areas such as wetlands should also be avoided to prevent damage to indigenous species that rely on an acidic environment.

  4. Impact of acid atmospheric deposition on soils: Field monitoring and aluminium chemistry.

    OpenAIRE

    Mulder, J.

    1988-01-01

    The effect of acid atmospheric deposition on concentrations and transfer of major solutes in acid, sandy soils was studied. Emphasis was given to mobilization and transport of potentially toxic aluminum. Data on solute concentrations and fluxes in meteoric water as well as soil solutions were obtained from intensive monitoring programmes conducted at a number of sites in northwestern Europe and North-America. Specific hypotheses were tested in laboratory experiments.Atmospheric acid inputs do...

  5. Acidic deposition in the northeastern United States: Sources and inputs, ecosystem effects, and management strategies

    Science.gov (United States)

    Driscoll, C.T.; Lawrence, G.B.; Bulger, A.J.; Butler, T.J.; Cronan, C.S.; Eagar, C.; Lambert, K.F.; Likens, G.E.; Stoddard, J.L.; Weathers, K.C.

    2001-01-01

    North America and Europe are in the midst of a large-scale experiment. Sulfuric and nitric acids have acidified soils, lakes, and streams, thereby stressing or killing terrestrial and aquatic biota. It is therefore critical to measure and to understand the recovery of complex ecosystems in response to decreases in acidic deposition. Fortunately, the NADP, CASTNet, and AIRMoN-dry networks are in place to measure anticipated improvements in air quality and in atmospheric deposition. Unfortunately, networks to measure changes in water quality are sparse, and networks to monitor soil, vegetation, and fish responses are even more limited. There is an acute need to assess the response of these resources to decreases in acid loading. It would be particularly valuable to assess the recovery of aquatic biota - which respond directly to acid stress - to changes in surface water chemistry (Gunn and Mills 1998). We used long-term research from the HBEF and other sites across the northeastern United States to synthesize data on the effects of acidic deposition and to assess ecosystem responses to reductions in emissions. On the basis of existing data, it is clear that in the northeastern United States ??? reductions of SO2 emissions since 1970 have resulted in statistically significant decreases in SO42- in wet and bulk deposition and in surface waters ??? emissions of NOX and concentrations of NO3- in wet and bulk deposition and in surface waters have shown no increase or decrease since the 1980s ??? estimates of NH3 emissions are uncertain, although atmospheric deposition of NH4+ remains important for forest management and stream NO3- loss ??? acidic deposition has accelerated the leaching of base cations from soils, thus delaying the recovery of ANC in lakes and streams from decreased emissions of SO2 (at the HBEF the available soil Ca pool appears to have declined 50% over the past 50 years) ???sulfur and N from atmospheric deposition have accumulated in forest soils across

  6. Acid deposition critical loads modeling for the simulation of sulfur exceedance and reduction in Guangdong, China

    Institute of Scientific and Technical Information of China (English)

    QIU Rongliang; WANG Shizhong; QIU Hao; WANG Xuemei; LIAO Jin; ZHANG Zhentian

    2009-01-01

    In this study, the current acid deposition critical loads in Guangdong, China were calculated using the PROFILE model with a 3×3 km resolution.Calculations were carried out for critical loads of potential acidity, actual acidity, sulfur and nitrogen, with values in extents of 0-3.5, 0-14.0, 0-26.0 and 0-3.5 kmol/(hm2·year), respectively.These values were comparable to previously reported results and reflected the influences of vegetation and soil characteristics on the soil acid buffering capacity.Simulations of SO2 emission and sulfur deposition in this study showed that sulfur deposition core areas mirrored SO2 emission centers.The prediction of sulfur deposition after 20% and 40% reduction of SO2 emission suggested that the reduction of area sources contributed greatly to the decrease of sulfur deposition.Thus, abatement of area source emissions could be the primary way to mitigate sulfur deposition in Guangdong so as to meet both the provincial and national regulations of air pollution control.

  7. Humic Acid Composition and Characteristics of Soil Organic Matter in Relation to the Elevation Gradient of Moso Bamboo Plantations.

    Science.gov (United States)

    Wang, Hsueh-Ching; Chou, Chiao-Ying; Chiou, Chyi-Rong; Tian, Guanglong; Chiu, Chih-Yu

    2016-01-01

    Studying the influence of climatic and/or site-specific factors on soil organic matter (SOM) along an elevation gradient is important for understanding the response of SOM to global warming. We evaluated the composition of SOM and structure of humic acids along an altitudinal gradient from 600 to 1400 m in moso bamboo (Phyllostachys edulis) plantations in central Taiwan using NMR spectroscopy and photometric analysis. Total organic C and total nitrogen (N) content increased with increasing elevation. Aromaticity decreased and ΔlogK (the logarithm of the absorbance ratio of humic acids at 400 and 600 nm) increased with increasing elevation, which suggests that SOM humification decreased with increasing elevation. High temperature at low elevations seemed to enhance the decomposition (less accumulation of total organic C and N) and humification (high aromaticity and low ΔlogK). The alkyl-C/O-alkyl-C (A/O-A) ratio of humic acids increased with increasing elevation, which suggests that SOM humification increased with increasing elevation; this finding was contrary to the trend observed for ΔlogK and aromaticity. Such a discrepancy might be due to the relatively greater remaining of SOM derived from high alkyl-C broadleaf litter of previous forest at high elevations. The ratio of recalcitrant C to total organic C was low at low elevations, possibly because of enhanced decomposition of recalcitrant SOM from the previous broadleaf forest during long-term intensive cultivation and high temperature. Overall, the change in SOM pools and in the rate of humification with elevation was primarily affected by changes in climatic conditions along the elevation gradient in these bamboo plantations. However, when the composition of SOM, as assessed by NMR spectroscopy and photometric analysis was considered, site-specific factors such as residual SOM from previous forest and intensive cultivation history could also have an important effect on the humic acid composition and

  8. Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

    Energy Technology Data Exchange (ETDEWEB)

    Deen, I. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Zhitomirsky, I., E-mail: zhitom@mcmaster.ca [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2014-02-15

    Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties.

  9. Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

    International Nuclear Information System (INIS)

    Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties

  10. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Armitage, Heather F., E-mail: h.armitage@abdn.ac.u [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Britton, Andrea J. [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Woodin, Sarah J. [Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Wal, Rene van der [Aberdeen Centre for Environmental Sustainability (ACES), School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom)

    2011-01-15

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha{sup -1} yr{sup -1}) and a low N deposition site, Ben Wyvis (7.2 kg ha{sup -1} yr{sup -1}). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  11. Suppression of rice methane emission by sulfate deposition in simulated acid rain

    OpenAIRE

    Gauci, Vincent; Dise, Nancy B; Howell, Graham; Jenkins, Meaghan E.

    2008-01-01

    Sulfate in acid rain is known to suppress methane (CH4) emissions from natural freshwater wetlands. Here we examine the possibility that CH4 emissions from rice agriculture may be similarly affected by acid rain, a major and increasing pollution problem in Asia. Our findings suggest that acid rain rates of SO2-4 deposition may help to reduce CH4 emissions from rice agriculture. Emissions from rice plants treated with simulated acid rain at levels of SO2-4 consistent with the range of depositi...

  12. Deposition of LDH on plasma treated polylactic acid to reduce water permeability

    KAUST Repository

    Bugatti, Valeria

    2013-04-01

    A simple and scalable deposition process was developed to prepare polylactic acid (PLA) coatings with enhanced water barrier properties for food packaging applications. This method based on electrostatic interactions between the positively charged layers of layered double hydroxides (LDHs) modified with ionic liquids (ILs) and the negatively charged plasma treated polylactic acid leads to homogeneous, stable, and highly durable coatings. Deposition of the LDH coatings increases the surface hydrophobicity of the neat PLA, which results to a decrease in water permeability by about 35%. © 2013 Elsevier Inc.

  13. Scanning Tunnelling Microscopy Observation on 10,12-Tricosadiynoic Acid Monolayers Deposited by Schaefer's Method

    Institute of Scientific and Technical Information of China (English)

    张耿民

    2001-01-01

    The Langmuir-Blodgett monolayers of 10, 12-tricosadiynoic acid molecules were deposited onto the basal plane of highly oriented pyrolytic graphite (HOPG) by Schaefer's method and then observed with the scanning tunnelling microscope (STM). With a view to achieving a parallel molecular arrangement on the graphite surface, the deposition was deliberately conducted at a relatively low surface pressure. As exhibited by the STM images, by this approach the 10,12-tricosadiynoic acid molecules could constitute an ordered structure with their molecular chains lying parallel to the substrate. The model of molecular dimer is put forward for the interpretation of the observed phenomena.

  14. Descriptive risk assessment of the effects of acidic deposition on Rocky Mountain amphibians

    Science.gov (United States)

    Corn, Paul Stephen; Vertucci, Frank A.

    1992-01-01

    We evaluated the risk of habitat acidification to the six species of amphibians that occur in the mountains of Colorado and Wyoming. Our evaluation included extrinsic environmental factors (habitat sensitivity and amount of acidic atmospheric deposition) and species-specific intrinsic factors (sensitivity to acid conditions, habitat preferences, and timing of breeding). Only one of 57 surveyed localities had both acid neutralizing capacity μeq/L and sulfate deposition >10 kg/ha/yr, extrinsic conditions with a possible risk of acidification. Amphibian breeding habitats in the Rocky Mountains do not appear to be sufficiently acidic to kill amphibian embryos. Some species breed in high-elevation vernal pools during snowmelt, and an acidic pulse during snowmelt may pose a risk to embryos of these species. However, the acidic pulse, if present, probably occurs before open water appears and before breeding begins. Although inherent variability of amphibian population size may make detection of declines from anthropogenic effects difficult, acidic deposition is unlikely to have caused the observed declines of Bufo boreas and Rana pipiens in Colorado and Wyoming. Amphibians in the Rocky Mountains are not likely to be at risk with acidification inputs at present levels.

  15. Acidification of Forest Soils: A Model for Analyzing Impacts of Acidic Deposition in Europe - Version II

    OpenAIRE

    Kauppi, P.; Kaemaeri, J.; Posch, M; Kauppi, L.; Matzner, E.

    1985-01-01

    Acidification is an unfavorable process in forest soils. Timber logging, natural accumulation of biomass in the ecosystem, and acidic deposition are sources of acidification. Acidification causes a risk of damage to plant roots and a subsequent risk of a decline in ecosystem productivity. A dynamic model is introduced for describing the acidification of forest soils. In one-year time steps the model calculates the soil pH as function of acid stress and the buffer mechanisms of the soil. ...

  16. Acidification of Forest Soils: Model Development and Application for Analyzing Impacts of Acidic Deposition in Europe

    OpenAIRE

    P. E. Kauppi; KÀmÀri, J.; Posch, M; Kauppi, L.; Matzner, E.

    1984-01-01

    Acidification is considered as an unfavorable process in forest soils. Timber logging, natural accumulation of biomass in the ecosystem, and acidic deposition are known as sources of acidification. Acidification causes the risk of damage to plant roots and subsequent risk of a decline in ecosystem productivity. A dynamic model is introduced for describing the acidification of forest soils. In one-year time steps the model calculates the soil pH as function of the acid stress and the buff...

  17. Assessment of the effect of acid deposition on forest soils in Stockholm County

    Energy Technology Data Exchange (ETDEWEB)

    Odlare, M. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Forest Soils

    1997-05-01

    The objective of this study was to assess how the acidity in the upper layer of forest soils in Stockholm County is affected by acid deposition. The acidity balance in a long-term perspective was assessed by a steady state mass balance model approach. The model involved a procedure where all significant acidifying processes were weighted against the neutralizing process. If the acidity balance reached a value higher than zero, the critical load of the soil has been exceeded. The acidity balance was calculated for 91 forest sample sites throughout Stockholm County. Two different data sets were used: 22 sites from the National Survey of Forest Soils and Vegetation, and 69 sites from the Forestry Board. The acidity balance was assessed in relation to four different scenarios: (1) Present deposition, whole tree harvesting; (2) Present deposition, stem harvesting; (3) 30% reduction in deposition, whole tree harvesting; and (4) 30% reduction in deposition, stem harvesting. A majority of the sites reached a positive acidity balance in all scenarios, i.e. they had exceeded the critical load. However, the values decreased with stem harvesting and 30% reduction in deposition. A 30% reduction together with stem harvesting gave the result that 59% of the sites from the National Survey of Forest Soils and Vegetation and 55% of the sites from the forestry Board achieved a positive balance. That is, almost half of the sites did not exceed the critical load. It is therefore likely that scenario 4 is close to the 50 percentile of exceeding the critical load. After studying the different parameters in the model, it seems that the most important factors for the difference between sites are base cation uptake and weathering. The sample sites that did not reach excessive levels had a low base cation uptake in comparison with other parameters and a relatively high weathering rate. It seems that acidification on the 91 sample sites is less dependent on acid deposition and more on tree

  18. Integrated assessment of acid deposition impacts using reduced-form modeling. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, R.; Small, M.J.

    1996-05-01

    Emissions of sulfates and other acidic pollutants from anthropogenic sources result in the deposition of these acidic pollutants on the earth`s surface, downwind of the source. These pollutants reach surface waters, including streams and lakes, and acidify them, resulting in a change in the chemical composition of the surface water. Sometimes the water chemistry is sufficiently altered so that the lake can no longer support aquatic life. This document traces the efforts by many researchers to understand and quantify the effect of acid deposition on the water chemistry of populations of lakes, in particular the improvements to the MAGIC (Model of Acidification of Groundwater in Catchments) modeling effort, and describes its reduced-form representation in a decision and uncertainty analysis tool. Previous reduced-form approximations to the MAGIC model are discussed in detail, and their drawbacks are highlighted. An improved reduced-form model for acid neutralizing capacity is presented, which incorporates long-term depletion of the watershed acid neutralization fraction. In addition, improved fish biota models are incorporated in the integrated assessment model, which includes reduced-form models for other physical and chemical processes of acid deposition, as well as the resulting socio-economic and health related effects. The new reduced-form lake chemistry and fish biota models are applied to the Adirondacks region of New York.

  19. Long-term development of acid deposition (1880–2030 in sensitive freshwater regions in Europe

    Directory of Open Access Journals (Sweden)

    W. Schöpp

    2003-01-01

    Full Text Available Time series of the deposition of acidifying substances are a pre-requisite for the study of the acidification and recovery of ecosystems such as surface waters. This paper reports the derivation and calculation of deposition trends of the potentially acidifying compounds SO2, NOx and NH3 in sensitive freshwater regions in Europe studied in the EU-funded RECOVER: 2010 project. The time interval covered is 151 years: from 1880, which can be considered as the pre-industrial era in most countries, to 2030, taking into account the consequences of current emission reduction agreements in Europe. The historic and predicted emissions for European countries are used to calculate the deposition development in the study areas, using meteorologically averaged atmospheric source-receptor transfer coefficients derived from the EMEP Lagrangian acid deposition model. These time series were used as driving forces for the application of the dynamic acidification model MAGIC to study the acidification and recovery of sensitive freshwater ecosystems in Europe. Keywords: acid deposition, historic depositions, sensitive lake regions, Europe

  20. Characterization of early microbial communities on volcanic deposits along a vegetation gradient on the island of Miyake, Japan.

    Science.gov (United States)

    Guo, Yong; Fujimura, Reiko; Sato, Yoshinori; Suda, Wataru; Kim, Seok-won; Oshima, Kenshiro; Hattori, Masahira; Kamijo, Takashi; Narisawa, Kazuhiko; Ohta, Hiroyuki

    2014-01-01

    The 2000 eruption of Mount Oyama on the island of Miyake (Miyake-jima) created a unique opportunity to study the early ecosystem development on newly exposed terrestrial substrates. In this study, bacterial and fungal communities on 9- and 11-year-old volcanic deposits at poorly to fully vegetation-recovered sites in Miyake-jima, Japan, were characterized by conventional culture-based methods and pyrosequencing of 16S rRNA and 18S rRNA genes. Despite the differences in the vegetation cover, the upper volcanic deposit layer samples displayed low among-site variation for chemical properties (pH, total organic carbon, and total nitrogen) and microbial population densities (total direct count and culturable count). Statistical analyses of pyrosequencing data revealed that the microbial communities of volcanic deposit samples were phylogenetically diverse, in spite of very low-carbon environmental conditions, and their diversity was comparable to that in the lower soil layer (buried soil) samples. Comparing with the microbial communities in buried soil, the volcanic deposit communities were characterized by the presence of Betaproteobacteria and Gammaproteobacteria as the main bacterial class, Deinococcus- Thermus as the minor bacterial phyla, and Ascomycota as the major fungal phyla. Multivariate analysis revealed that several bacterial families and fungal classes correlated positively or negatively with plant species. PMID:24463576

  1. EVALUATING CHANGES IN FOREST CONDITION POTENTIALLY RELATED TO ACIDIC DEPOSITION: AN EXAMPLE USING RED SPRUCE

    Science.gov (United States)

    As a result of concern about forest decline in Europe and the USA, research has been conducted to investigate changes in forest condition that might be associated with acidic deposition and related pollutants (principally ozone). ymptoms of tree decline observed in the field typi...

  2. Distribution and Orientation of Carbon Fibers in Polylactic Acid Parts Produced by Fused Deposition Modeling

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; W. Gutmann, Ingomar; Koch, Thomas;

    2016-01-01

    The aim of this paper is the understanding of the fiber orientation by investigations in respect to the inner configuration of a polylactic acid matrix reinforced with short carbon fibers after a fused deposition modeling extrusion process. The final parts were analyzed by X-ray, tomography...

  3. Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

    Science.gov (United States)

    Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying; Cheng, Yan; Zheng, Yufeng; Xi, Tingfei; Wei, Shicheng

    2013-11-01

    Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

  4. Economic valuation of acidic deposition damages: Preliminary results from the 1985 NAPAP [National Acid Precipitation Assessment Program] damage assessment

    International Nuclear Information System (INIS)

    This paper identifies methods used to evaluate the economic damages of acid deposition in the 1985 Damage Assessment being coordinated by the National Acid Precipitation Program. It also presents the preliminary estimates of economic damages for the Assessment. Economic damages are estimated for four effect areas: commercial agriculture and forests, recreational fishing and selected types of materials. In all but the last area, methods are used which incorporate the behavioral responses of individuals and firms or simulated physical damages to resources at risk. The preliminary nature of the estimated damages in each area is emphasized. Over all, the damage estimates should be interpreted with caution. 44 refs., 6 figs., 5 tabs

  5. DNA methylation landscape of fat deposits and fatty acid composition in obese and lean pigs

    Science.gov (United States)

    Zhang, Shunhua; Shen, Linyuan; Xia, Yudong; Yang, Qiong; Li, Xuewei; Tang, Guoqing; Jiang, Yanzhi; Wang, Jinyong; Li, Mingzhou; Zhu, Li

    2016-01-01

    Obese and lean type pig breeds exhibit differences in their fat deposits and fatty acid composition. Here, we compared the effect of genome-wide DNA methylation on fatty acid metabolism between Landrace pigs (LP, leaner) and Rongchang pigs (RP, fatty). We found that LP backfat (LBF) had a higher polyunsaturated fatty acid content but a lower adipocyte volume than RP backfat (RBF). LBF exhibited higher global DNA methylation levels at the genome level than RBF. A total of 483 differentially methylated regions (DMRs) were located in promoter regions, mainly affecting olfactory and sensory activity and lipid metabolism. In LBF, the promoters of genes related to ATPase activity had significantly stronger methylation. This fact may suggest lower energy metabolism levels, which may result in less efficient lipid synthesis in LBF. Furthermore, we identified a DMR in the miR-4335 and miR-378 promoters and validated their methylation status by bisulfite sequencing PCR. The hypermethylation of the promoters of miR-4335 and miR-378 in LBF and the resulting silencing of the target genes may result in LBF’s low content in saturated fatty acids and fat deposition capacity. This study provides a solid basis for exploring the epigenetic mechanisms affecting fat deposition and fatty acid composition. PMID:27721392

  6. Poly(aniline-co--aminobenzoic acid) deposited on poly(vinyl alcohol): Synthesis and characterization

    Indian Academy of Sciences (India)

    S Adhikari; P Banerji

    2013-08-01

    In this work, we have deposited poly(aniline-co--aminobenzoic acid) on poly(vinyl alcohol) (PVA) by in situ polymerization. The polymerization was effected within maleic acid (MA) cross-linked PVA hydrogel. The copolymer was obtained by oxidative polymerization of aniline hydrochloride and -aminobenzoic acid using ammonium persulfate as an oxidant. Instead of conventional solution polymerization, here synthesis was carried out on APS soaked MA cross-linked PVA (MA–PVA) film where the polymer was in situ deposited in its conducting form. The composite film was characterized by Fourier transform infra red (FT–IR) and ultraviolet visible (UV–VIS) spectroscopy and electrical measurements. Surface morphology of the composite films was studied by field emission scanning electron microscopy (FESEM). The variation of conductivity of the films was studied.

  7. Effects of Folic Acid on Secretases Involved in Aβ Deposition in APP/PS1 Mice.

    Science.gov (United States)

    Tian, Tian; Bai, Dong; Li, Wen; Huang, Guo-Wei; Liu, Huan

    2016-01-01

    Alzheimer's disease (AD) is the most common type of dementia. Amyloid-β protein (Aβ) is identified as the core protein of neuritic plaques. Aβ is generated by the sequential cleavage of the amyloid precursor protein (APP) via the APP cleaving enzyme (α-secretase, or β-secretase) and γ-secretase. Previous studies indicated that folate deficiency elevated Aβ deposition in APP/PS1 mice, and this rise was prevented by folic acid. In the present study, we aimed to investigate whether folic acid could influence the generation of Aβ by regulating α-, β-, and γ-secretase. Herein, we demonstrated that folic acid reduced the deposition of Aβ42 in APP/PS1 mice brain by decreasing the mRNA and protein expressions of β-secretase [beta-site APP-cleaving enzyme 1 (BACE1)] and γ-secretase complex catalytic component-presenilin 1 (PS1)-in APP/PS1 mice brain. Meanwhile, folic acid increased the levels of ADAM9 and ADAM10, which are important α-secretases in ADAM (a disintegrin and metalloprotease) family. However, folic acid has no impact on the protein expression of nicastrin (Nct), another component of γ-secretase complex. Moreover, folic acid regulated the expression of miR-126-3p and miR-339-5p, which target ADAM9 and BACE1, respectively. Taken together, the effect of folic acid on Aβ deposition may relate to making APP metabolism through non-amyloidogenic pathway by decreasing β-secretase and increasing α-secretase. MicroRNA (miRNA) may involve in the regulation mechanism of folic acid on secretase expression. PMID:27618097

  8. Declining acidic deposition begins reversal of forest-soil acidification in the northeastern U.S. and eastern Canada

    Science.gov (United States)

    Lawrence, Gregory B.; Hazlett, Paul W.; Fernandez, Ivan J.; Ouimet, Rock; Bailey, Scott W.; Shortle, Walter C.; Smith, Kevin T.; Antidormi, Michael

    2015-01-01

    Decreasing trends in acidic deposition levels over the past several decades have led to partial chemical recovery of surface waters. However, depletion of soil Ca from acidic deposition has slowed surface water recovery and led to the impairment of both aquatic and terrestrial ecosystems. Nevertheless, documentation of acidic deposition effects on soils has been limited, and little is known regarding soil responses to ongoing acidic deposition decreases. In this study, resampling of soils in eastern Canada and the northeastern U.S. was done at 27 sites exposed to reductions in wet SO42– deposition of 5.7–76%, over intervals of 8–24 y. Decreases of exchangeable Al in the O horizon and increases in pH in the O and B horizons were seen at most sites. Among all sites, reductions in SO42– deposition were positively correlated with ratios (final sampling/initial sampling) of base saturation (P soils have begun to reverse.

  9. GRADIENT DISTRIBUTION OF ACID RAIN IN THE SCENIC RESORT OF THE BAIYUN MOUNTAIN IN GUANGZHOU

    Institute of Scientific and Technical Information of China (English)

    黄健; 李福娇; 江奕光; 李琼

    2004-01-01

    This paper analyzes the samples of rainwater from January to October 1999 at three monitoring sites of Baiyun Mountain and of aerosol composition in near-surface layer in January and June 1999 at two sites. The results suggest that (1) The pH value of rainwater is between 3.13 and 7.18, and the frequency of acid rain is more than 58 %. With the ascent of the monitoring sites, the pH value of rainwater decreases, and the frequency of acid rain increases. (2) In January, the chemical aerosol compositions at different altitudes are similar, but in June the acidity of aerosol rises at the higher site because of the increase of SO42-. (3) In rainwater, the proportion is such that SO42- is the most significant anion and Ca2+ is the most important cation, but both of them decrease as the altitude ascends. The proportion of NO3- and NH4+ rise at the higher site and have more contribution to the acidity of rainwater. (4) As the impact of automobile emissions around Baiyun Mountain, the proportion of NO3-/SO42-molecular concentration reaches 0.40, and NO3- is relatively more important to the rain acidity at the higher site.

  10. Deposition kinetics and characterization of stable ionomers from hexamethyldisiloxane and methacrylic acid by plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Urstöger, Georg; Resel, Roland; Koller, Georg; Coclite, Anna Maria

    2016-04-01

    A novel ionomer of hexamethyldisiloxane and methacrylic acid was synthesized by plasma enhanced chemical vapor deposition (PECVD). The PECVD process, being solventless, allows mixing of monomers with very different solubilities, and for polymers formed at high deposition rates and with high structural stability (due to the high number of cross-links and covalent bonding to the substrate) to be obtained. A kinetic study over a large set of parameters was run with the aim of determining the optimal conditions for high stability and proton conductivity of the polymer layer. Copolymers with good stability over 6 months' time in air and water were obtained, as demonstrated by ellipsometry, X-Ray reflectivity, and FT-IR spectroscopy. Stable coatings showed also proton conductivity as high as 1.1 ± 0.1 mS cm-1. Chemical analysis showed that due to the high molecular weight of the chosen precursors, it was possible to keep the plasma energy-input-per-mass low. This allowed limited precursor fragmentation and the functional groups of both monomers to be retained during the plasma polymerization.

  11. Effect of acetic acid on electrochemical deposition of carbon-nitride thin film

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Electrochemical deposition method was employed to prepare CNx thin film from methanol-urea solution,and it was shown that adding a little acetic acid in the solution significantly affected the deposition process.After optimizing the experiment conditions,we obtained polycrystalline grains with sizes of about 3―7μm on the faces of single crystal silicon.X-ray diffraction spectrua indicate that the grains are mainly composed of cubic phase mixed with a small amount of β and α phases.

  12. Distribution and Orientation of Carbon Fibers in Polylactic Acid Parts Produced by Fused Deposition Modeling

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; W. Gutmann, Ingomar; Koch, Thomas;

    2016-01-01

    The aim of this paper is the understanding of the fiber orientation by investigations in respect to the inner configuration of a polylactic acid matrix reinforced with short carbon fibers after a fused deposition modeling extrusion process. The final parts were analyzed by X-ray, tomography, and ...... magnetic resonance imaging allowing a resolved orientation of the fibers and distribution within the part. The research contributes to the understanding of the fiber orientation and fiber reinforcement of fused deposition modeling parts in additive manufacturing....

  13. Inkjet deposition of itraconazole onto poly(glycolic acid) microneedle arrays.

    Science.gov (United States)

    Boehm, Ryan D; Jaipan, Panupong; Skoog, Shelby A; Stafslien, Shane; VanderWal, Lyndsi; Narayan, Roger J

    2016-03-01

    Poly(glycolic acid) microneedle arrays were fabricated using a drawing lithography process; these arrays were modified with a drug release agent and an antifungal agent by piezoelectric inkjet printing. Coatings containing poly(methyl vinyl ether-co-maleic anhydride), a water-soluble drug release layer, and itraconazole (an antifungal agent), were applied to the microneedles by piezoelectric inkjet printing. Microscopic evaluation of the microneedles indicated that the modified microneedles contained the piezoelectric inkjet printing-deposited agents and that the surface coatings were released in porcine skin. Energy dispersive x-ray spectrometry aided in confirmation that the piezoelectric inkjet printing-deposited agents were successfully applied to the desired target areas of the microneedle surface. Fourier transform infrared spectroscopy was used to confirm the presence of the component materials in the piezoelectric inkjet printing-deposited material. Itraconazole-modified microneedle arrays incubated with agar plates containing Candida albicans cultures showed zones of growth inhibition. PMID:26869165

  14. Studies of acid deposition and its effects in two small catchments in Hunan, China

    Directory of Open Access Journals (Sweden)

    N. Xue

    2003-01-01

    Full Text Available Acid deposition and its effects were studied by analysing the chemistry in precipitation, stream water, soil water and soils in two catchments in Hunan. One site, Linkesuo (denoted LKS, is on the outskirts of Changsha, the provincial capital of Hunan, the other (Bailutang, denoted BLT on the outskirts of Chenzhou in southern Hunan. Volume-weighted average pH values and sulphate concentrations in wet deposition were 4.58 (BLT and 4.90 (LKS and 174 μmolc L-1 and 152 μmolc L-1, respectively. Wet deposition of sulphate has been estimated as 4.3 gS m-2yr-1 and 3.4 gS m-2yr-1 at BLT and LKS, respectively. Estimates of the corresponding total depositions (dry + wet are 6.1 gS m-2yr-1 and 5.3 gS m-2yr-1. In precipitation and throughfall, sulphate was the major anion and calcium the major cation. In stream and soil water, nitrate was slightly higher than sulphate on an equivalent basis and magnesium (Mg not much lower than calcium (Ca. Important soil properties, such as soil pH, soil organic matter (SOM content, exchangeable acidic cations, exchangeable base cations, effective cation exchange capacity (CECe, base saturation (BS, and aluminium (Al and iron (Fe pools, were determined for five forest soil profiles (consisting of four horizons in each of the two catchments. The soils in BLT are generally more acid, have lower BS and higher Al and Fe pools than the LKS soils. The Al- and Fe-pools were generally higher in the topsoils (i.e. the O and A horizons than in deeper soils (i.e. E and B horizons especially at the most acidic site (BLT. There are significant correlations between Fe-pools and the corresponding Al-pools in both catchments except between the amorphous Feox and Alox. Considering the long-term high deposition of sulphate, there is a risk of future ecological damage due to acidification, especially in the BLT catchment, although vegetation damage has yet to be observed in the catchments. This condition appears to be representative of a

  15. Modeling wet deposition of acid substances over the PRD region in China

    Science.gov (United States)

    Lu, Xingcheng; Fung, Jimmy Chi Hung; Wu, Dongwei

    2015-12-01

    The Pearl River Delta (PRD) region in southern China has suffered heavily from acid rain in the last 10 years due to the anthropogenic emission of sulfur dioxide and nitrogen dioxide. Several measurement-based studies about this issue have been conducted to analyze the chemical composition of precipitation in this area. However, no detailed, high resolution numerical simulation regarding this topic has ever been done in this region. In this study, the WRF-SMOKE-CMAQ system was applied to simulate the wet deposition of acid substances (SO42- and NO3-) in the PRD region from 2009 to 2011 with a resolution of 3 km. The simulation output agreed well with the observation data. Our results showed that Guangzhou was the city most affected by acid rain in this region. The ratio of non-sea-salt sulfate to nitrate indicated that the acid rain in this region belonged to the sulfate-nitrate mixed type. The source apportionment result suggests that point source and super regional source are the ones that contribute the pollutants most in the rain water over PRD Region. The sulfate and nitrate input to some reservoirs via wet deposition was also estimated based on the model simulation. Our results suggest that further cross-city cooperation and emission reduction are needed to further curb acid rain in this region.

  16. Genetic and metabolic regulation of fatty acid deposition in autochthonous bovine breeds with distinct genetic background

    OpenAIRE

    Costa, Ana Sofia Henriques da

    2013-01-01

    Tese de Doutoramento em Ciências Veterinárias. Especialidade de Produção Animal During the finishing phase, bovines deposit large amounts of subcutaneous and visceral fats resulting in production inefficiencies affecting, in particular, meat quality. Intramuscular fat composition of ruminant meats influences the quality of the final product, which explains the importance of assessing meat fatty acid profile using different breeds and feeding strategies. On the other hand, both genetic back...

  17. Distribution and diversity of carbon monoxide-oxidizing bacteria and bulk bacterial communities across a succession gradient on a Hawaiian volcanic deposit.

    Science.gov (United States)

    Weber, C F; King, G M

    2010-07-01

    Relatively little is known about the distribution and diversity of CO-oxidizing bacteria during succession on volcanic deposits even though they are among the primary colonists. We surveyed CO-oxidizing communities across a vegetation gradient on a 1959 cinder deposit using coxL (large subunit gene of carbon monoxide dehydrogenase) sequences. Sequences most closely related to a coxL sequence from Ktedonobacter racemifer, dominated unvegetated cinders, while Proteobacteria-like sequences dominated vegetated sites. The number of coxL operational taxonomic units (OTUs) increased threefold with increased vegetation, and correlated most strongly with the increased beta-Proteobacteria richness (r = 0.987). These compositional shifts were also reflected in overall bacterial community compositions as determined by 16S rRNA gene analysis. Notably, coxL OTU:16S rRNA OTU ratios increased with increased vegetation, indicating that CO oxidizers became a larger fraction of total bacterial richness during succession. Results from most probable number estimates and maximum potential CO uptake activity assays indicate that increased richness is paralleled by increased CO oxidizer abundance, which likely results from increased vegetation and organic carbon content. Collectively, results suggest that in contrast to patterns observed for plant succession, a versatile bacterial functional group that is important during early colonization and succession can remain important in later stages of succession, irrespective of dramatic environmental changes.

  18. Gradient in the degree of Crassulacean acid metabolism within leaves of Kalanchoe daigremontiana.

    Science.gov (United States)

    Winter, K

    1987-09-01

    Leaves of the Crassulacean acid metabolism plant Kalanchoe daigremontiana Hamet et Perr., about 3.3 mm thick, showed higher rates of net CO2 exchange through the lower than through the upper surface during day and night, although the lower surface received only a small fraction of the light which was incident on the upper surface. Nocturnal acidification was more pronounced in cells from the lower than from the upper portion of leaves. The lower activity of the exposed side of these long-lived succulent leaves may be related to the potentially adverse effects of excessive light. PMID:24225791

  19. Facile plasma-enhanced deposition of ultrathin crosslinked amino acid films for conformal biometallization.

    Science.gov (United States)

    Anderson, Kyle D; Slocik, Joseph M; McConney, Michael E; Enlow, Jesse O; Jakubiak, Rachel; Bunning, Timothy J; Naik, Rajesh R; Tsukruk, Vladimir V

    2009-03-01

    A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma-enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one-step, solvent-free process. This approach is applicable to many practical surfaces and allows surface-induced biometallization while avoiding multiple wet-chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.

  20. Nutritional status of Abies pinsapo forests along a nitrogen deposition gradient: do C/N/P stoichiometric shifts modify photosynthetic nutrient use efficiency?

    Science.gov (United States)

    Blanes, Ma Carmen; Viñegla, Benjamín; Merino, José; Carreira, José A

    2013-04-01

    Chronic atmospheric N deposition has modified relative N availability, altering the biogeochemical cycles of forests and the stoichiometry of nutrients in trees, inducing P limitation, and modifying the N:P ratios of plant biomass. This study examines how the variation in the foliar stoichiometry of Abies pinsapo across an N deposition gradient affects foliar traits and photosynthetic rate. We measured the maximum net assimilation rates (Amax) and the foliar nitrogen (N) and phosphorus (P) concentrations in A. pinsapo needles of five age classes. The leaf mass per area and photosynthetic N and P use efficiencies (PNUE and PPUE, respectively) were also estimated. The results from the N-saturated stand (Sierra Bermeja, B) differed from the comparable N-limited stands under investigation (Yunquera, Y, and Sierra Real, SR). The trees from Y and SR exhibited a reduction in the N content in older needles, whereas the foliar N concentration at the B site increased with needle age. N and P were positively correlated at Y and SR, but not at B, suggesting that the overload of N in the trees at site B has exceeded the homeostatic regulation capacity of the N-saturated stand in terms of foliar stoichiometry. A max and PNUE were correlated positively with P and negatively with the N/P ratio at the three study sites. The foliar N concentration was positively correlated with A max at Y and SR. However, this relationship was negative for the B site. These findings suggest that the nutritional imbalance caused by increased chronic deposition of N and an insufficient supply of P counteracts the potential increase in net photosynthesis induced by the accumulation of foliar N. PMID:23011850

  1. Transport of acid forming emissions and potential effects of deposition in northeastern Alberta and northern Saskatchewan: a problem analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shewchuk, S.R.; Abouguendia, Z.M.; Atton, F.M.; Dublin, J.; Godwin, R.C.; Holowaychuk, N.; Hopkinson, R.; Liaw, W.K.; Maybank, J.; Padbury, G.A.

    1981-01-01

    The purpose of this report is to study the potential effects of acid rain in northeastern Alberta and northern Saskatchewan. A problem analysis was conducted of the transport, transformations and deposition of emissions in this region. Studied are the atmospheric processes, geology and soils, natural vegetation, and the aquatic systems. At present, no environmental damage attributable to acidic deposition has been detected in this region. Field surveys in the region have detected no effects of industrial emissions on vegetation except within a few kilometers of industrial operations. The earliest effects of acid deposition tend to appear within aquatic systems. Ten recommendations based on these findings are discussed. 109 references, 22 figures, 10 tables.

  2. A novel acidophile community populating waste ore deposits at an acid mine drainage site

    Institute of Scientific and Technical Information of China (English)

    HAO Chun-bo; ZHANG Hong-xun; BAI Zhi-hui; HU Qing; ZHANG Bao-guo

    2007-01-01

    Waste ore samples (pH 3.0) were collected at an acid mine drainage site in Anhui, China. The present acidophilic microbial community in the waste ore was studied with 16S rRNA gene clone library and denaturing gradient gel electrophoresis (DGGE). Eighteen different clones were identified and affiliated with Actinobacteria, low G + C Gram-positives, Thermomicrobia, Acidobacteria, Proteobacteria, Candidate division TM7, and Planctomycetes. Phylogenetic analysis of 16S rRNA gene sequences revealed a diversity of acidophiles in the samples that were mostly novel. It is unexpected that the moderately thermophilic acidophiles were abundant in the acidic ecosystem and may play a great role in the generation of AMD. The result of DGGE was consistent with that of clone library analysis. These findings help in the better understanding of the generation mechanism of AMD and in developing a more efficient method to control AMD.

  3. Assessment of lake sensitivity to acidic deposition in national parks of the Rocky Mountains.

    Science.gov (United States)

    Nanus, L; Williams, M W; Campbell, D H; Tonnessen, K A; Blett, T; Clow, D W

    2009-06-01

    The sensitivity of high-elevation lakes to acidic deposition was evaluated in five national parks of the Rocky Mountains based on statistical relations between lake acid-neutralizing capacity concentrations and basin characteristics. Acid-neutralizing capacity (ANC) of 151 lakes sampled during synoptic surveys and basin-characteristic information derived from geographic information system (GIS) data sets were used to calibrate the statistical models. The explanatory basin variables that were considered included topographic parameters, bedrock type, and vegetation type. A logistic regression model was developed, and modeling results were cross-validated through lake sampling during fall 2004 at 58 lakes. The model was applied to lake basins greater than 1 ha in area in Glacier National Park (n = 244 lakes), Grand Teton National Park (n = 106 lakes), Great Sand Dunes National Park and Preserve (n = 11 lakes), Rocky Mountain National Park (n = 114 lakes), and Yellowstone National Park (n = 294 lakes). Lakes that had a high probability of having an ANC concentration 3000 m, with 80% of the catchment bedrock having low buffering capacity. The modeling results indicate that the most sensitive lakes are located in Rocky Mountain National Park and Grand Teton National Park. This technique for evaluating the lake sensitivity to acidic deposition is useful for designing long-term monitoring plans and is potentially transferable to other remote mountain areas of the United States and the world. PMID:19544737

  4. Effect of N deposition on tree amino acid concentrations in two Sphagnum species

    Energy Technology Data Exchange (ETDEWEB)

    Karsisto, M.; Kitunen, V. [Finnish Forest Research Inst., Vantaa (Finland). Vantaa Research Centre; Jauhiainen, J. [Joensuu Univ. (Finland). Dept. of Biology; Vasander, H. [Helsinki Univ. (Finland). Dept. of Forest Ecology

    1996-12-31

    Nitrogen saturation of ecosystems occurs when the availability of nitrogen is not a growth limiting factor. This situation can be reached through fertilisation or by nitrogen deposition. Prolonged nitrogen saturation may overload the ecosystem and cause changes in the vigour and eventually in the composition of plant communities. But before this stage is reached, certain changes in nitrogen metabolism occur. These changes can be used as an early warning of nitrogen overload to ecosystems. A change in the amino acid pool of plants has been used as an indication of various kind of stress, including, temperature, nutrient imbalance, shading, drought or excess water. It has been postulated that such stresses have an effect on protein synthesis but not on the nitrogen uptake of plants. The result is an increase in the concentration of NH{sub 4}{sup +} ions in plant cells, which may have toxic effects to the plant and the processes that assimilate the free NH{sub 4}{sup +} ions. One of such process is the synthesis of amino acids, especially those containing a significant proportion of nitrogen, e.g. arginine, glutamine and asparagine. This study about the quantification of amino acids in two species of Sphagnum mosses is part of a larger study, the aim of which is to clarify how a number of Sphagnum species will cope with climatic change and nitrogen deposition. Sphagna are the most important members of the peat forming communities in the boreal zone. Sphagnum communities are formed by species specialised to grow in conditions of low nutrient availability, mainly provided via deposition. The present structure and composition of mire communities may be endangered due to elevated levels of nitrogen deposition that have persisted over the last few decades. (20 refs.)

  5. Evaluation and mapping of relative sensitivity of the terrestrial ecosystems to acidic deposition in Fujian

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the semi-quantitative approach, four environmental factors of sites (i.e. bedrock lithology, soil type, land use, and rainfall) were categorized, weighted and combined to determine and assess the relative sensitivity of the terrestrial ecosystems to acidic deposition in Fujian Province. Then the factors have been digitized and combined to assign an overall value for each mesh square (16.77 km ′ 18.39 km) by using the geographic information system (GIS). The results indicated that the most sensitive area in Fujian was mainly located in the southeast, and the least sensitive area was distributed sporadically in the east along the coast. Due to slow weathering rate of siliceous rocks, acid to weakly acid reactions of the soils, along with the greater percent of coniferous forests, more than 80 percent of the total area exhibits higher sensitivity classes (4-7).

  6. Nitrogen Deposition Via N+ Implantation:Implications for Primordial Amino Acids Synthesis Revisited

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; SHI Huaibin; WANG Xiangqin; YU Zengliang

    2007-01-01

    In this paper amino acids synthesis in aqueous solution induced by ion implantation,which was possibly ubiquitous on primitive Earth,is investigated.As a discharge using a graphite rod as the anode under a nitrogen atmosphere was performed against ammonia water,it was found that three kinds of amino acids were produced.They were glycine,serine and alanine.By introducing ion implantation into the carboxylate solution,ammonia and amino acids were also formed via nitrogen deposition/fixation.Another isotopic experiment showed that both OH and H radicals played a crucial role in the arc-discharge-promoted reactions in aqueous solution Therefore,we believe that the impact of ions in the original atmospheric conditions might have functioned as a promoter in the chemical origin and evolution of life.

  7. Effect of lactic acid on nucleation morphology and surface roughness of electroless Ni–P deposition in nanoscale

    Indian Academy of Sciences (India)

    A Babanejhad; M Hashemi; Y Rahmatallahpur; Sh A Nozad

    2012-08-01

    The present work aims to study effect of lactic acid concentration as complexing agent on surface roughness and nucleation morphology of electroless N–P deposition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to study nucleation morphology and surface roughness of deposition. Deposition process started at some initial priority growing centres independently distributed on the substrate. We found that the morphology and surface roughness of deposition strongly depends on the complexing agent concentration. Morphology of initial deposited centres with no concentration of lactic acid was in coniform structure. By increasing the complexing agent concentration, the structure of initial growing centres changed from coniform to nodular shape and the surface roughness of depositions decreased.

  8. Tuning Acid-Base Properties Using Mg-Al Oxide Atomic Layer Deposition.

    Science.gov (United States)

    Jackson, David H K; O'Neill, Brandon J; Lee, Jechan; Huber, George W; Dumesic, James A; Kuech, Thomas F

    2015-08-01

    Atomic layer deposition (ALD) was used to coat γ-Al2O3 particles with oxide films of varying Mg/Al atomic ratios, which resulted in systematic variation of the acid and base site areal densities. Variation of Mg/Al also affected morphological features such as crystalline phase, pore size distribution, and base site proximity. Areal base site density increased with increasing Mg content, while acid site density went through a maximum with a similar number of Mg and Al atoms in the coating. This behavior leads to nonlinearity in the relationship between Mg/Al and acid/base site ratio. The physical and chemical properties were elucidated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, and CO2 and NH3 temperature-programmed desorption (TPD). Fluorescence emission spectroscopy of samples grafted with 1-pyrenebutyric acid (PBA) was used for analysis of base site proximity. The degree of base site clustering was correlated to acid site density. Catalytic activity in the self-condensation of acetone was dependent on sample base site density and independent of acid site density.

  9. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    Energy Technology Data Exchange (ETDEWEB)

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  10. Acidic deposition, cation mobilization, and biochemical indicators of stress in healthy red spruce

    Science.gov (United States)

    Shortle, W.C.; Smith, K.T.; Minocha, R.; Lawrence, G.B.; David, M.B.

    1997-01-01

    Dendrochemical and biochemical markers link stress in apparently healthy red spruce trees (Picea rubens) to acidic deposition. Acidic deposition to spruce forests of the northeastern USA increased sharply during the 1960s. Previous reports related visible damage of trees at high elevations to root and soil processes. In this report, dendrochemical and foliar biochemical markers indicate perturbations in biological processes in healthy red spruce trees across the northeastern USA. Previous research on the dendrochemistry of red spruce stemwood indicated that under uniform environmental conditions, stemwood concentrations of Ca and Mg decreased with increasing radial distance from the pith. For nine forest locations, frequency analysis shows that 28 and 52% of samples of red spruce stemwood formed in the 1960s are enriched in Ca and Mg, respectively, relative to wood formed prior to and after the 1960s. This enrichment in trees throughout the northeastern USA may be interpretable as a signal of increased availability of essential cations in forest soils. Such a temporary increase in the availability of Ca and Mg could be caused by cation mobilization, a consequence of increased acidic deposition. During cation mobilization, essential Ca and Mg as well as potentially harmful Al become more available for interaction with binding sites in the soil and absorbing roots. As conditions which favor cation mobilization continue, Ca and Mg can be leached or displaced from the soil. A measure of the interaction between Ca and Al is the Al/Ca binding ratio (molar charge ratio of exchangeable Al to exchangeable Ca). As the Al/Ca binding ratio in the root zone increased from 0.3 to 1.9, the foliar concentration of the biochemical stress marker putrescine also increased from 45 to 145 nm g-1. The correlation of the putrescine concentration to the Al/Ca binding ratio (adj. r2 = 0.68, P < 0.027) suggests that foliar stress may be linked to soil chemistry.

  11. Acid deposition and watershed characteristics in relation to lake chemistry in northeastern Minnesota

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, G.; Allert, J.D.; Liukkonen, B.W.; Loucks, O.L.; Glass, G.E.

    1985-01-01

    The relationship between lake sensitivity to atmospheric acidic inputs and the neutralization capacity of watersheds is examined for 267 lakes in northeastern Minnesota. Three water chemistry/sensitivity measures (color, sulfate, and alkalinity) are correlated with variables representative of precipitation and sulfate inputs, hydrology, and the acid-neutralization capacity of various watershed components. An ordinal scale for ranking bedrock and surficial deposit neutralization capacity is presented. The watershed variables found to account for the largest percentages of the variability in measured color, sulfate, and alkalinity levels are determined. The results illustrate important averaging properties of watersheds from small headwater systems to large drainages and the difficulty in obtaining correlations for some water-quality measures (e.g., alkalinity) when some variables, such as soils and land cover, are available only as large-area averages.

  12. Friction and wear study of diamond-like carbon gradient coatings on Ti6Al4V substrate prepared by plasma source ion implant-ion beam enhanced deposition

    International Nuclear Information System (INIS)

    DLC gradient coatings had been deposited on Ti6Al4V alloy substrate by plasma source ion implantation-ion beam enhanced deposition method and their friction and wear behavior sliding against ultra high molecular weight polyethylene counterpart were investigated. The results showed that DLC gradient coated Ti6Al4V had low friction coefficient, which reduced 24, 14 and 10% compared with non-coated Ti6Al4V alloy under dry sliding, lubrication of bovine serum and 0.9% NaCl solution, respectively. DLC gradient coated Ti6Al4V showed significantly improved wear resistance, the wear rate was about half of non-coated Ti6Al4V alloy. The wear of ultra high molecular weight polyethylene counterpart was also reduced. High adhesion to Ti6Al4V substrate of DLC gradient coatings and surface structure played important roles in improved tribological performance, serious oxidative wear was eliminated when DLC gradient coating was applied to the Ti6Al4V alloy

  13. Effect of polyaspartic acid on hydroxyapatite deposition in silk fibroin blend films

    Directory of Open Access Journals (Sweden)

    2010-05-01

    Full Text Available Polyaspartic acid/silk fibroin/hydroxyapatite (PASP/SF-HA composites have been synthesized by biomimetic processing. SF solution was mixed with different contents of PASP to prepare the PASP/SF blend membranes. After ethanol treatment and premineralization process, the blend membranes were immersed into 1.5 simulated body fluid (1.5 SBF for 24 h to induce apatite deposition at 37±0.5°C. Fourier transform infrared spectroscopy (FTIR and X-ray diffraction (XRD results revealed that a conformation transition of SF occurred after the addition of PASP and ethanol treatment. The FTIR and XRD results also confirmed that the main component of apatite deposition was HA. Scanning electron microscopy (SEM showed that the content of HA increased with increasing PASP concentration .Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP results revealed that the Ca/P molar ratio could reach 1.45, which was close to the Ca/P ratio of apatite. It was appropriate to conclude that the increasing content of PASP had a distinct effect on HA deposition in the blend films.

  14. Sulfur stable isotopic compositions as indicators of acid deposition histories in lakes

    International Nuclear Information System (INIS)

    Atmospheric acid deposition in perturbing many aquatic and terrestrial ecosystems in the northeastern US. Sulfate is one component of this deposition, and they have been studying the sulfur chemistry of lake sediments that record changes in sulfur deposition histories. They are measuring %S, S in organic and inorganic fractions, and 34S/32S isotopic compositions. Initial findings show that pyrite (FeS2) is a major component of many recent lake sediments. Pyrite is formed in the high-iron lake sediments where anaerobic sulfate reducing bacteria actively produce sulfides. Sulfate levels are a key in determining the activities of these bacteria, and the recent sulfate increases are sufficient to cause widespread stimulation of sulfide production in many lake sediments. Isotopic fractionation during sulfate reduction causes sulfides to be depleted in 34S and have low δ34S values. Addition of sulfides to sediments increases total %S, amounts of inorganic sulfur species and results in shifts toward lower δ34S values. They are using these changes to estimate historical and contemporary contributions to the sulfur record in sediments

  15. Physical vapour deposition of alkyl phosphonic acid on mica and HOPG investigated by NC-AFM

    International Nuclear Information System (INIS)

    We investigate the growth of octadecylphosphonic acid (OPA) self-assembly molecules prepared by physical vapour deposition (PVD) on mica and highly oriented pyrolytic graphite (HOPG) under ultrahigh-vacuum conditions. On samples prepared by immersion from diluted solution on mica self-assembled monolayers are formed, whereas by PVD and subsequent annealing we observe the formation of almost perfect self-assembled bilayers slightly tilted with respect to the surface normal. On the non-polar surface of HOPG, the vapour-deposited molecules adsorb in bilayers parallel to the surface, similar to the films produced by spread coating (Fontes and Neves 2005 Langmuir 21 11113). On all samples we deduce the molecular ordering by means of noncontact atomic force microscopy; on HOPG, even submolecular resolution is obtained. A comparison of our vapour-deposited films with samples prepared by other techniques mentioned in the literature demonstrates that PVD yields excellent film quality, and in many applications might be preferred due to its clean, solution-free environment and the possibility for exact dosage, e.g. for multilayer formation with a defined thickness

  16. Depositional ice nucleation on solid ammonium sulfate and glutaric acid particles

    Directory of Open Access Journals (Sweden)

    K. J. Baustian

    2010-03-01

    Full Text Available Heterogeneous ice nucleation on solid ammonium sulfate and glutaric acid particles was studied using optical microscopy and Raman spectroscopy. Optical microscopy was used to detect selective nucleation events as water vapor was slowly introduced into an environmental sample cell. Particles that nucleated ice were dried via sublimation and examined in detail using Raman spectroscopy. Depositional ice nucleation is highly selective and occurred preferentially on just a few ammonium sulfate and glutaric acid particles in each sample. For freezing temperatures between 214 K and 235 K an average ice saturation ratio of S = 1.10±0.07 for solid ammonium sulfate was observed. Over the same temperature range, S values observed for ice nucleation on glutaric acid particles increased from 1.2 at 235 K to 1.6 at 218 K. Experiments with externally mixed particles further show that ammonium sulfate is a more potent ice nucleus than glutaric acid. Our results suggest that heterogeneous nucleation on ammonium sulfate may be an important pathway for atmospheric ice nucleation and cirrus cloud formation when solid ammonium sulfate aerosol particles are available for ice formation. This pathway for ice formation may be particularly significant near the tropical tropopause region where sulfates are abundant and other species known to be good ice nuclei are depleted.

  17. nC60 deposition kinetics: the complex contribution of humic acid, ion concentration, and valence.

    Science.gov (United States)

    McNew, Coy P; LeBoeuf, Eugene J

    2016-07-01

    The demonstrated toxicity coupled with inevitable environmental release of nC60 raise serious concerns about its environmental fate and transport, therefore it is crucial to understand how nC60 will interact with subsurface materials including attached phase soil and sediment organic matter (AP-SOM). This study investigated the attachment of nC60 onto a Harpeth humic acid (HHA) coated silica surface under various solution conditions using a quartz crystal microbalance with dissipation monitoring. The HHA coating greatly enhanced nC60 attachment at low ion concentrations while hindering attachment at high ion concentrations in the presence of both mono and divalent cations. At low ion concentrations, the HHA greatly reduced the surface potential of the silica, enhancing nC60 deposition through reduction in the electrostatic repulsion. At high ion concentrations however, the reduced surface potential became less important due to the near zero energy barrier to deposition and therefore non-DLVO forces dominated, induced by compaction of the HHA layer, and leading to hindered attachment. In this manner, observed contributions from the HHA layer were more complex than previously reported and by monitoring surface charge and calculated DLVO interaction energy alongside attachment experiments, this study advances the mechanistic understanding of the variable attachment contributions from the humic acid layer. PMID:27061365

  18. Acid deposition and watershed characteristics in relation to lake chemistry in northeastern Minnesota

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, G. Jr.; Allert, J.D.; Liukkonen, B.W.; Ilse, J.A.; Loucks, O.L.; Glass, G.E.

    1985-01-01

    The relationship between lake sensitivity to atmospheric acidic inputs and the neutralization capacity of watersheds is examined for 267 lakes in northeastern Minnesota. Three water chemistry/sensitivity measures (color, sulfate, and alkalinity) are correlated with variables representative of precipitation and sulfate inputs, hydrology, and the acid neutralization capacity of various watershed components. An ordinal scale for ranking bedrock and surficial deposit neutralization capacity is presented. The watershed variables found to account for the largest percentages of the variability in measured color, sulfate, and alkalinity levels are determined. Color is strongly related to the presence of peat or marsh and hydrologic renewal time, whereas sulfate is primarily related to atmospheric deposition, evaporative concentration, bedrock type, and the presence of coniferous forest. Variation in alkalinity is the most difficult of the water chemistry measures to explain; for headwater lakes, atmospheric sulfate input, water renewal time, the presence of deciduous forest, and the weatherability of underlying bedrock determine much of its variability. The results illustrate important averaging properties of watersheds from small headwater systems to large drainages and the difficulty in obtaining correlations for some water quality measures (e.g., alkalinity) when some variables, such as soils and land cover, are available only as large-area averages. 52 references, 7 tables.

  19. U(VI) speciation and reduction in acid chloride fluids in hydrothermal conditions: from transport to deposition of uranium in unconformity-related deposits

    International Nuclear Information System (INIS)

    Circulations of acidic chloride brines in the earth's crust are associated with several types of uranium deposits, particularly unconformity-related uranium (URU) deposits. The spectacular high grade combined with the large tonnage of these deposits is at the origin of the key questions concerning the geological processes responsible for U transport and precipitation. The aim of this work is to performed experimental studies of U(VI) speciation and its reduction to U(IV) subsequently precipitation to uraninite under hydrothermal condition. About uranium transport, the study of U(VI) speciation in acidic brines at high temperature is performed by Raman and XAS spectroscopy, showing the coexistence of several uranyl chloride complexes UO2Cln2-n (n = 0 - 5). From this study, complexation constants are proposed. The strong capability of chloride to complex uranyl is at the origin of the transport of U(VI) at high concentration in acidic chloride brines. Concerning uranium precipitation, the reactivity of four potential reductants under conditions relevant for URU deposits genesis is investigated: H2, CH4, Fe(II) and the C-graphite. The kinetics of reduction reaction is measured as a function of temperature, salinity, pH and concentration of reductant. H2, CH4, and the C-graphite are very efficient while Fe(II) is not able to reduce U(VI) in same conditions. The duration of the mineralizing event is controlled by (i) the U concentration in the ore-forming fluids and (ii) by the generation of gaseous reductants, and not by the reduction kinetics. These mobile and efficient gaseous reductant could be at the origin of the extremely focus and massive character of ore in URU deposits. Finally, first partition coefficients uraninite/fluid of trace elements are obtained. This last part opens-up new perspectives on (i) REE signatures interpretation for a given type of uranium deposit (ii) and reconstruction of mineralizing fluids composition. (author)

  20. Effect of acidic deposition on productivity of forest ecosystem and estimation of its economic losses in southern suburbs of Chongqing

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    In accordance with principle sand methods of ecology,this paper studied the effects of acidic deposition on productivity and volume increment of masson pine and Cinnamomum campora forest which are widely distributed in southern suburbs of Chongqing. Based on the field data and measurements, a multivariable stepwise regression model was established to analyze the effects of multiple environmental factors on the productivity of the forest ecosystems. This model was used to assess the volume and economic losses of these two forest ecosystems caused by acidic deposition. The results showed that, among the environmental factors, pH value of precipitation, soil depth, soil organic contents and slope are the dominant ones influencing the growth of masson pine forest. It is also shown that the acidic deposition has no clear relation to the growth of C.Campora forest, so development of such broad-leaved forest is suitable in the area.

  1. Effect of Time and Deposition Method on Quality of Phosphonic Acid Modifier Self-Assembled Monolayers on Indium Zinc Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Lingzi; Knesting, Kristina M.; Bulusu, Anuradha; Sigdel, Ajaya K.; Giordano, Anthony J.; Marder, Seth R.; Berry, Joseph J.; Graham, Samuel; Ginger, David S.; Pemberton, Jeanne E.

    2016-12-15

    Phosphonic acid (PA) self-assembled monolayers (SAMs) are utilized at critical interfaces between transparent conductive oxides (TCO) and organic active layers in organic photovoltaic devices (OPVs). The effects of PA deposition method and time on the formation of close-packed, high-quality monolayers is investigated here for SAMs fabricated by solution deposition, micro-contact printing, and spray coating. The solution deposition isotherm for pentafluorinated benzylphosphonic acid (F5BnPA) on indium-doped zinc oxide (IZO) is studied using polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS) at room temperature as a model PA/IZO system. Fast surface adsorption occurs within the first min; however, well-oriented high-quality SAMs are reached only after -48 h, presumably through a continual process of molecular adsorption/desorption and monolayer filling accompanied by molecular reorientation. Two other rapid, soak-free deposition techniques, micro-contact printing and spray coating, are also explored. SAM quality is compared for deposition of phenyl phosphonic acid (PPA), F13-octylphosphonic acid (F13OPA), and pentafluorinated benzyl phosphonic acid (F5BnPA) by solution deposition, micro-contact printing and spray coating using PM-IRRAS. In contrast to micro-contact printing and spray coating techniques, 48-168 h solution deposition at both room temperature and 70 degrees C result in contamination- and surface etch-free close-packed monolayers with good reproducibility. SAMs fabricated by micro-contact printing and spray coating are much less well ordered.

  2. Early indications of soil recovery from acidic deposition in U.S. red spruce forests

    Science.gov (United States)

    Lawrence, Gregory B.; Shortle, Walter C.; David, Mark B.; Smith, Kevin T.; Warby, Richard A.F.; Lapenis, Andrei G.

    2012-01-01

    Forty to fifty percent decreases in acidic deposition through the 1980s and 1990s led to partial recovery of acidified surface waters in the northeastern United States; however, the limited number of studies that have assessed soil change found increased soil acidification during this period. From existing data, it's not clear whether soils continued to worsen in the 1990s or if recovery had begun. To evaluate possible changes in soils through the 1990s, soils in six red spruce (Picea rubens Sarg.) stands in New York, Vermont, New Hampshire, and Maine, first sampled in 1992 to 1993, were resampled in 2003 to 2004. The Oa-horizon pH increased (P 42−, which decreased the mobility of Al throughout the upper soil profile. Results indicate a nascent recovery driven largely by vegetation processes.

  3. Responses of Soil Acid Phosphomonoesterase Activity to Simulated Nitrogen Deposition in Three Forests of Subtropical China

    Institute of Scientific and Technical Information of China (English)

    HUANG Wen-Juan; LIU Shi-Zhong; CHU Guo-Wei; ZHANG De-Qiang; LI Yue-Lin; LU Xian-Kai; ZHANG Wei; HUANG Juan; D. OTIENO; Z. H. XU; LIU Ju-Xiu

    2012-01-01

    Soil acid phosphomonoesterase activity (APA) plays a vital role in controlling phosphorus (P) cycling and reflecting the current degree of P limitation Responses of soil APA to elevating nitrogen (N) deposition are important because of their potential applications in addressing the relationship between N and P in forest ecosystems.A study of responses of soll APA to simulated N deposition was conducted in three succession forests of subtropical China.The three forests include a Masson pine (Pinus massoniana) forest (MPF)—pioneer community,a coniferous and broad-leaved mixed forest (MF)—transition community and a monsoon evergreen broadleaved forest (MEBF)—climax community.Four N treatments were designed for MEBF:control (without N added),low-N (50 kg N ha-1 year-1),and medium-N (100 kg N ha-1 year-1) and high-N (150 kg N ha-1 year-1),and only three N treatments (i.e.,control,low-N,mediun-N) were established for MPF and MF.Results showed that soil APA was highest in MEBF.followed by MPF and MF.Soil APAs in both MPF and MF were not influenced by low-N treatments but depressed in medium-N trcatments.However,soil APA in MEBF exhibited negative responses to high N additions,indicating that the environment of enhanced N depositions would reduce P supply for the mature forest ecosystem.Soil APA and its responses to N additions in subtropical forests were closely related to the succession stages in the forests.

  4. Simulation of acid mine drainage generation around Küre VMS Deposits, Northern Turkey

    Science.gov (United States)

    Demirel, Cansu; Kurt, Mehmet Ali; Çelik Balci, Nurgül

    2015-04-01

    experiments with mixed acidophiles at higher temperatures. Further depleted Fe(III) values coinciding with decreasing pH may point to precipitation of secondary phases (i.e. jarosite). This study revealed that the metals (Fe, Cu, Co and Zn) released during short term leaching of the ore (34 days) are generally caused by acid produced by dissolution reactions rather than oxidation. In the long term experiments a more complex biogeochemical reactions (oxidation and dissolution) take place in conjunction. Key words: Bioleaching, AMD, heavy metal release, environment, acidophilic bacteria, Küre copper ore deposits, volcanogenic massive sulfide deposits

  5. Uranium deposits associated to tertiary acid volcanism of the Pena Blanca Sierra (Chihuahua, Mexico)

    International Nuclear Information System (INIS)

    The uraniferous deposits located in the Sierra de Pena Blanca (Chihuahua, Mexico) are the consequence of successive events that modified acid volcanic rocks. The devitrification of the Nopal Formation, vitroclastic tuffs, is esential in the cooling history because it releases uranium that becomes available. The uranium present in fluids as uranylcarbonate complexes, precipitate along the lamellea of hematite (exsolutions of the ilmenites). The presence of sulfur causes the destabilization of the ilmenites with uranium oxide (pitchblende - titanium oxide - pyrite), the pseudomorph of magnetites (pitchblende - pyrite) and the transformation of hematite into pyrite. The silice coming from the kaolinization of feldspars recristallizes as microcristalline quartz so that the rock appears compact. Fractures cause the uplifting of the lower unit of Nopal formation. It has been altered to montmorillonite. A carbonatation of this tuff has been observed and these two types of alteration occur after kaolinization. The Escuadra formation overlies the Nopal formation. The deposition takes place on an eroded basement where a soil developed. The two formations will together undergo transformations due to the saturation level and the primary ore will be only oxidized or oxidized, transported and reconcentrated. Late and localized thermal activities have been observed and may be the result of tectonic movements occurring after the supergene modification

  6. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, S.S. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Shinde, P.S. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Sapkal, R.T. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Oh, Y.W. [Department of Nano-Engineering, Kyungnam University, Masan 631-701 (Korea, Republic of); Haranath, D. [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110 012 (India); Bhosale, C.H. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India); Rajpure, K.Y., E-mail: rajpure@yahoo.com [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416004 (India)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Influence of substrate temperature onto the physico-chemical properties. Black-Right-Pointing-Pointer Photochemical, structural, luminescent, optoelectrical and thermal properties. Black-Right-Pointing-Pointer The kinetics of oxalic acid degradation with reaction mechanism. Black-Right-Pointing-Pointer Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV-Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (I{sub sc} = 0.357 mA) and open circuit voltage (V{sub oc} = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14-3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  7. Photoelectrocatalytic degradation of oxalic acid by spray deposited nanocrystalline zinc oxide thin films

    International Nuclear Information System (INIS)

    Highlights: ► Influence of substrate temperature onto the physico-chemical properties. ► Photochemical, structural, luminescent, optoelectrical and thermal properties. ► The kinetics of oxalic acid degradation with reaction mechanism. ► Extent of mineralization by COD and TOC. - Abstract: The high quality nano-crystalline zinc oxide thin films are deposited onto corning glasses by spray pyrolysis technique. The influence of reaction temperature onto their photoelectrochemical, structural, morphological, optoelectronic, luminescence and thermal properties has been investigated. The structural characteristics studied by X-ray diffractometry has complemented by resistivity measurements and UV–Vis spectroscopy. The photoelectrochemical activity shows enhancement in short circuit current (Isc = 0.357 mA) and open circuit voltage (Voc = 0.48 V). Direct band gap calculated by considering R and T values of ZnO thin films increases from 3.14–3.21 eV exhibiting a slight blue shift in band edge. Three characteristic luminescence peaks having near band-edge, blue and green emission are observed in the photoluminescence spectra. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in films. Photocatalytic degradation of oxalic acid followed with reaction mechanism by using zinc oxide photoelectrode under solar illumination has been investigated.

  8. Wetlands serve as natural sources for improvement of stream ecosystem health in regions affected by acid deposition

    Science.gov (United States)

    Pound, Katrina L; Lawrence, Gregory B.; Passy, Sophia I.

    2013-01-01

    For over 40 years, acid deposition has been recognized as a serious international environmental problem, but efforts to restore acidified streams and biota have had limited success. The need to better understand the effects of different sources of acidity on streams has become more pressing with the recent increases in surface water organic acids, or 'brownification' associated with climate change and decreased inorganic acid deposition. Here, we carried out a large scale multi-seasonal investigation in the Adirondacks, one of the most acid-impacted regions in the United States, to assess how acid stream producers respond to local and watershed influences and whether these influences can be used in acidification remediation. We explored the pathways of wetland control on aluminum chemistry and diatom taxonomic and functional composition. We demonstrate that streams with larger watershed wetlands have higher organic content, lower concentrations of acidic anions, and lower ratios of inorganic to organic monomeric aluminum, all beneficial for diatom biodiversity and guilds producing high biomass. Although brownification has been viewed as a form of pollution, our results indicate that it may be a stimulating force for biofilm producers with potentially positive consequences for higher trophic levels. Our research also reveals that the mechanism of watershed control of local stream diatom biodiversity through wetland export of organic matter is universal in running waters, operating not only in hard streams, as previously reported, but also in acid streams. Our findings that the negative impacts of acid deposition on Adirondack stream chemistry and biota can be mitigated by wetlands have important implications for biodiversity conservation and stream ecosystem management. Future acidification research should focus on the potential for wetlands to improve stream ecosystem health in acid-impacted regions and their direct use in stream restoration, for example, through

  9. The Gane Roof Project: The Impact of Reduced N and S Deposition and Experimental Warming in an Acid Grassland

    International Nuclear Information System (INIS)

    A field-based system used to quantify the response of acid grassland to reduced atmospheric nitrogen and sulphur deposition, and to investigate the effects of elevated soil temperature on acid grassland development is described. The system is based on 12 retractable roofs, covering undisturbed experimental plots of acid grassland and three controls. Nine roofs are used to exclude natural precipitation and three roofs used to retain emitted IR radiation at night. An irrigation system has been developed to simulate natural precipitation, allowing for the application of specific treatment regimes of ambient, reduced nitrogen and reduced nitrogen/sulphur deposition beneath the nine rain exclusion plots. Plant, soil parameters, leachate chemistry and gaseous fluxes are being monitored and initial results on soil water chemistry are described. Warming appeared to enhance nitrate concentrations in soil water but this was not sustained beyond the first year of treatment. In contrast, the deposition reduction treatments decreased soil water nitrate concentrations within a few weeks of reducing deposition. This was not observed for other solutes such as sulphate or ammonium suggesting a more direct link between deposition of nitrate and leaching losses

  10. The GANE Roof Project: The impact of reduced N and S deposition and experimental warming in an acid grassland

    International Nuclear Information System (INIS)

    A field-based system used to quantify the response of acid grassland to reduced atmospheric nitrogen and sulphur deposition, and to investigate the effects of elevated soil temperature on acid grassland development is described. The system is based on 12 retractable roofs, covering undisturbed experimental plots of acid grassland and three controls. Nine roofs are used to exclude natural precipitation and three roofs used to retain emitted IR radiation at night. An irrigation system has been developed to simulate natural precipitation, allowing for the application of specific treatment regimes of ambient, reduced nitrogen and reduced nitrogen/sulphur deposition beneath the nine rain exclusion plots. Plant, soil parameters, leachate chemistry and gaseous fluxes are being monitored and initial results on soil water chemistry are described. Warming appeared to enhance nitrate concentrations in soil water but this was not sustained beyond the first year of treatment. In contrast, the deposition reduction treatments decreased soil water nitrate concentrations within a few weeks of reducing deposition. This was not observed for other solutes such as sulphate or ammonium suggesting a more direct link between deposition of nitrate and leaching losses

  11. [Effect of artificial NaC1 and KC1 gradients on the active transport of organic acids in energy-depleted kidney proximal tubules. II. The KC1 gradient].

    Science.gov (United States)

    Mozhaeva, M G; Bresler, V M; Nikiforov, A A

    1982-07-01

    The stimulatory effect of KCL in bath medium on fluorescein uptake in superficial proximal tubules in the absence of Na in bath medium was observed on Na- and energy-depleted slices of the rat kidney outer cortex. In the absence of K gradient between bath medium and tubular cells, the fluorescein uptake increased with raising the intracellular K concentration. The efflux of fluorescein from the tubules was inversely proportional to K concentration in the cells. Visual control showed that at high K concentrations fluorescein was accumulated mainly in the tubular walls (i. e. in the cytoplasm of tubular cells). It is suggested that the raise of K concentration in cells results in the intracellular binding of organic acid.

  12. QA/QC activities and ecological monitoring in the Acid Deposition Monitoring Network in East Asia (EANET

    Directory of Open Access Journals (Sweden)

    Ueda H

    2009-01-01

    Full Text Available An overview is presented of Quality assurance/Quality control QA/QC activities and current features of the ecological monitoring in the frame of the Acid Deposition Monitoring Network in East Asia EANET. It is stressed that standardization of the methodologies applicable for new topics, such as the catchment analysis and ozone impacts, should be investigated for future monitoring.

  13. Protein and lipid deposition rates in male broiler chickens : separate responses to amino acids and protein-free energy

    NARCIS (Netherlands)

    Eits, R.M.; Kwakkel, R.P.; Verstegen, M.W.A.; Stoutjesdijk, P.; Greef, de K.H.

    2002-01-01

    Two experiments of similar design were conducted with male broiler chickens over two body weight ranges, 200 to 800 g in Experiment 1 and 800 to 1,600 g in Experiment 2. The data were used to test the hypothesis that protein deposition rate increases (linearly) with increasing amino acid intake, unt

  14. Eddy covariance emission and deposition flux measurements using proton transfer reaction - time of flight - mass spectrometry (PTR-TOF-MS): comparison with PTR-MS measured vertical gradients and fluxes

    Science.gov (United States)

    Park, J.-H.; Goldstein, A. H.; Timkovsky, J.; Fares, S.; Weber, R.; Karlik, J.; Holzinger, R.

    2013-02-01

    During summer 2010, a proton transfer reaction - time of flight - mass spectrometer (PTR-TOF-MS) and a quadrupole proton transfer reaction mass spectrometer (PTR-MS) were deployed simultaneously for one month in an orange orchard in the Central Valley of California to collect continuous data suitable for eddy covariance (EC) flux calculations. The high time resolution (5 Hz) and high mass resolution (up to 5000 m/Δm) data from the PTR-TOF-MS provided the basis for calculating the concentration and flux for a wide range of volatile organic compounds (VOC). Throughout the campaign, 664 mass peaks were detected in mass-to-charge ratios between 10 and 1278. Here we present PTR-TOF-MS EC fluxes of the 27 ion species for which the vertical gradient was simultaneously measured by PTR-MS. These EC flux data were validated through spectral analysis (i.e., co-spectrum, normalized co-spectrum, and ogive). Based on inter-comparison of the two PTR instruments, no significant instrumental biases were found in either mixing ratios or fluxes, and the data showed agreement within 5% on average for methanol and acetone. For the measured biogenic volatile organic compounds (BVOC), the EC fluxes from PTR-TOF-MS were in agreement with the qualitatively inferred flux directions from vertical gradient measurements by PTR-MS. For the 27 selected ion species reported here, the PTR-TOF-MS measured total (24 h) mean net flux of 299 μg C m-2 h-1. The dominant BVOC emissions from this site were monoterpenes (m/z 81.070 + m/z 137.131 + m/z 95.086, 34%, 102 μg C m-2 h-1) and methanol (m/z 33.032, 18%, 72 μg C m-2 h-1). The next largest fluxes were detected at the following masses (attribution in parenthesis): m/z 59.048 (mostly acetone, 12.2%, 36.5 μg C m-2 h-1), m/z 61.027 (mostly acetic acid, 11.9%, 35.7 μg C m-2 h-1), m/z 93.069 (para-cymene + toluene, 4.1%, 12.2 μg C m-2 h-1), m/z 45.033 (acetaldehyde, 3.8%, 11.5 μg C m-2 h-1), m/z 71.048 (methylvinylketone + methacrolein, 2.4%, 7

  15. How two gravity-gradient inversion methods can be used to reveal different geologic features of ore deposit - A case study from the Quadrilátero Ferrífero (Brazil)

    Science.gov (United States)

    Carlos, Dionísio U.; Uieda, Leonardo; Barbosa, Valeria C. F.

    2016-07-01

    Airborne gravity gradiometry data have been recently used in mining surveys to map the 3D geometry of ore deposits. This task can be achieved by different gravity-gradient inversion methods, many of which use a voxel-based discretization of the Earth's subsurface. To produce a unique and stable solution, an inversion method introduces particular constraints. One constraining inversion introduces a depth-weighting function in the first-order Tikhonov regularization imposing a smoothing on the density-contrast distributions that are not restricted to near-surface regions. Another gravity-gradient inversion, the method of planting anomalous densities, imposes compactness and sharp boundaries on the density-contrast distributions. We used these two inversion methods to invert the airborne gravity-gradient data over the iron-ore deposit at the southern flank of the Gandarela syncline in Quadrilátero Ferrífero (Brazil). Because these methods differ from each other in the particular constraint used, the estimated 3D density-contrast distributions reveal different geologic features of ore deposit. The depth-weighting smoothing inversion reveals variable dip directions along the strike of the retrieved iron-ore body. The planting anomalous density inversion estimates a compact iron-ore mass with a single density contrast, which reveals a variable volume of the iron ore along its strike increasing towards the hinge zone of the Gandarela syncline which is the zone of maximum compression. The combination of the geologic features inferred from each estimate leads to a synergistic effect, revealing that the iron-ore deposit is strongly controlled by the Gandarela syncline.

  16. Long-term recovery of lakes in the Adirondack region of New York to decreases in acidic deposition

    Science.gov (United States)

    Waller, Kristin; Driscoll, Charles; Lynch, Jason; Newcomb, Dani; Roy, Karen

    2012-01-01

    After years of adverse impacts to the acid-sensitive ecosystems of the eastern United States, the Acid Rain Program and Nitrogen Budget Program were developed to control sulfur dioxide (SO 2) and nitrogen oxide (NO x) emissions through market-based cap and trade systems. We used data from the National Atmospheric Deposition Program's National Trends Network (NTN) and the U.S. EPA Temporally Integrated Monitoring of Ecosystems (TIME) program to evaluate the response of lake-watersheds in the Adirondack region of New York to changes in emissions of sulfur dioxide and nitrogen oxides resulting from the Acid Rain Program and the Nitrogen Budget Program. TIME is a long-term monitoring program designed to sample statistically selected subpopulations of lakes and streams across the eastern U.S. to quantify regional trends in surface water chemistry due to changes in atmospheric deposition. Decreases in wet sulfate deposition for the TIME lake-watersheds from 1991 to 2007 (-1.04 meq m -2-yr) generally corresponded with decreases in estimated lake sulfate flux (-1.46 ± 0.72 meq m -2-yr), suggesting declines in lake sulfate were largely driven by decreases in atmospheric deposition. Decreases in lake sulfate and to a lesser extent nitrate have generally coincided with increases in acid neutralizing capacity (ANC) resulting in shifts in lakes among ANC sensitivity classes. The percentage of acidic Adirondack lakes (ANC metrics should theoretically show similar responses, ANC calc (+2.03 μeq L -1-yr) increased at more than twice the rate as ANC G (+0.76 μeq L -1-yr). This discrepancy has important implications for assessments of lake recovery and appears to be due to compensatory increases in concentrations of naturally occurring organic acids coincident with decreases in lake concentrations of strong acid anions, as evidenced by increases in concentrations of dissolved organic carbon.

  17. DEPOSITION TANK CORROSION TESTING FOR ENHANCED CHEMICAL CLEANING POST OXALIC ACID DESTRUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.

    2011-08-29

    An Enhanced Chemical Cleaning (ECC) process is being developed to aid in the high level waste tank closure at the Savannah River Site. The ECC process uses an advanced oxidation process (AOP) to destroy the oxalic acid that is used to remove residual sludge from a waste tank prior to closure. The AOP process treats the dissolved sludge with ozone to decompose the oxalic acid through reactions with hydroxyl radicals. The effluent from this oxalic acid decomposition is to be sent to a Type III waste tank and may be corrosive to these tanks. As part of the hazardous simulant testing that was conducted at the ECC vendor location, corrosion testing was conducted to determine the general corrosion rate for the deposition tank and to assess the susceptibility to localized corrosion, especially pitting. Both of these factors impact the calculation of hydrogen gas generation and the structural integrity of the tanks, which are considered safety class functions. The testing consisted of immersion and electrochemical testing of A537 carbon steel, the material of construction of Type III tanks, and 304L stainless steel, the material of construction for transfer piping. Tests were conducted in solutions removed from the destruction loop of the prototype ECC set up. Hazardous simulants, which were manufactured at SRNL, were used as representative sludges for F-area and H-area waste tanks. Oxalic acid concentrations of 1 and 2.5% were used to dissolve the sludge as a feed to the ECC process. Test solutions included the uninhibited effluent, as well as the effluent treated for corrosion control. The corrosion control options included mixing with an inhibited supernate and the addition of hydroxide. Evaporation of the uninhibited effluent was also tested since it may have a positive impact on reducing corrosion. All corrosion testing was conducted at 50 C. The uninhibited effluent was found to increase the corrosion rate by an order of magnitude from less than 1 mil per year (mpy

  18. Atmospheric deposition of beryllium in Central Europe: Comparison of soluble and insoluble fractions in rime and snow across a pollution gradient

    International Nuclear Information System (INIS)

    Little is known about atmospheric input of beryllium (Be) into ecosystems, despite its highly toxic behavior. For three consecutive winters (2009–2011), we measured Be concentrations in horizontal deposition (rime) and vertical deposition (snow) at 10 remote mountain-top locations in the Czech Republic, Central Europe. Beryllium was determined both in filtered waters, and in HF digests of insoluble particles. Across the sites, soluble Be concentrations in rime were 7 times higher, compared to snow (6.1 vs. 0.9 ng·L−1). Rime scavenged the pollution-rich lower segments of clouds. The lowest Be concentrations were detected in the soluble fraction of snow. Across the sites, 34% of total Be deposition occurred in the form of soluble (bioavailable) Be, the rest were insoluble particles. Beryllium fluxes decreased in the order: vertical dry deposition insoluble > vertical dry deposition soluble > horizontal deposition soluble > vertical wet deposition insoluble > vertical wet deposition soluble > horizontal deposition insoluble. The average contributions of these Be forms to total deposition were 56, 21, 8, 7, 5 and 3%, respectively. Sites in the northeast were more Be-polluted than the rest of the country with sources of pollution in industrial Silesia. -- Highlights: ► We measured Be concentrations in rime and snow in the Czech Republic. ► Soluble Be concentrations in rime were 7 times higher than in snow. ► 34% of total Be deposition occurred in the form of soluble (bioavailable) Be. ► Dry-deposited fluxes dominated Be inputs. ► Soluble Be concentrations only rarely exceeded 30 ng·L−1.

  19. Nicotinic acid supplementation in diet favored intramuscular fat deposition and lipid metabolism in finishing steers.

    Science.gov (United States)

    Yang, Zhu-Qing; Bao, Lin-Bin; Zhao, Xiang-Hui; Wang, Can-Yu; Zhou, Shan; Wen, Lu-Hua; Fu, Chuan-Bian; Gong, Jian-Ming; Qu, Ming-Ren

    2016-06-01

    Nicotinic acid (NA) acting as the precursor of NAD(+)/NADH and NADP(+)/NADPH, participates in many biochemical processes, e.g. lipid metabolism. The main purpose of this study was to investigate the effects of dietary NA on carcass traits, meat quality, blood metabolites, and fat deposition in Chinese crossbred finishing steers. Sixteen steers with the similar body weight and at the age of 24 months were randomly allocated into control group (feeding basal diet) and NA group (feeding basal diet + 1000 mg/kg NA). All experimental cattle were fed a 90% concentrate diet and 10% forage straw in a 120-day feeding experiment. The results showed that supplemental NA in diet increased longissimus area, intramuscular fat content (17.14% vs. 9.03%), marbling score (8.08 vs. 4.30), redness (a*), and chroma (C*) values of LD muscle, but reduced carcass fat content (not including imtramuscular fat), pH24 h and moisture content of LD muscle, along with no effect on backfat thickness. Besides, NA supplementation increased serum HDL-C concentration, but decreased the serum levels of LDL-C, triglyceride, non-esterified fatty acid, total cholesterol, and glycated serum protein. In addition, NA supplementation increased G6PDH and ICDH activities of LD muscle. These results suggested that NA supplementation in diet improves the carcass characteristics and beef quality, and regulates the compositions of serum metabolites. Based on the above results, NA should be used as the feed additive in cattle industry. PMID:27048556

  20. Molecule modification andmass deposition induced bythe implantation of lowenergy Fe+ ion beamsinto amino acids

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fe+ ion beams with the energy of 110 keV were implanted into films of L(+)-cysteine (HSCH2CH(NH2)COOH). One of the single crystals grown in hydrochloric acid solution with the implanted samples through slow evaporation was structurally characterized by the X-ray crystallography. The crystal is monoclinic, space group C2, with a = 1.8534(4) nm, b = 0.5234(1) nm, c = 0.7212(1) nm, β= 103.72°, V = 0.67965(3) nm3, Z = 4, F(000) = 144.0, Dclac = 1.763 g@cm-3, μ(MoKα) = 1.06 mm-1, T = 293(2) K. R = 0.0379, wR = 0.0835 for 660 observed reflections (I > 2σ(I)). The structural formula of the crystal compound is (CH2CH(NH2)NO2)ClFe (Mr = 180.38 u). Products of heavy ion beam irradiation were purified and it was directly confirmed that the implanted Fe+ ions had been deposited in the novel molecules. The same doses of Fe+ ion beams of the same energy were implanted into films of L(+)-cysteine hydrochloride monohydrate. FTIR spectroscopy of the implanted samples proved that some of the original molecules were seriously damaged and significant modifications were induced.

  1. The effects of acid deposition on sulfate reduction and methane production in peatlands

    Science.gov (United States)

    Murray, Georgia L.; Hines, Mark E.; Bayley, Suzanne E.

    1992-01-01

    Peatlands, as fens and bods, make up a large percentage of northern latitude terrestrial environments. They are organic rich and support an active community of anaerobic bacteria, such as methanogenic and sulfate-reducing bacteria. The end products of these microbial activities, methane and hydrogen sulfide, are important components in the global biogeochemical cycles of carbon and sulfur. Since these two bacterial groups compete for nutritional substrates, increases in sulfate deposition due to acid rain potentially can disrupt the balance between these processes leading to a decrease in methane production and emission. This is significant because methane is a potent greenhouse gas that effects the global heat balance. A section of Mire 239 in the Experimental Lakes Area, in Northwestern Ontario, was artificially acidified and rates of sulfate reduction and methane production were measured with depth. Preliminary results suggested that methane production was not affected immediately after acidification. However, concentrations of dissolved methane decreased and dissolved sulfide increased greatly after acidification and both took several days to recover. The exact mechanism for the decrease in methane was not determined. Analyses are under way which will be used to determine rates of sulfate reduction. These results will be available by Spring and will be discussed.

  2. Response surface methodology to optimize gradient ion chromatographic separation of inorganic anions and organic acids in tobacco leaves

    Institute of Scientific and Technical Information of China (English)

    Rui Qi Wang; Na Ni Wang; Jia Jie Zhang; Yan Zhu

    2011-01-01

    The separation optimization of nine organic and inorganic anions in tobacco leaves using gradient ion chromatography by response surface methodology was investigated. In order to achieve this goal the usefulness of the chromatographic response function (CRF) for the evaluation of the two different chromatographic performance goals (resolution and analysis time) was tested. The experiments were performed according to a Box-Behnken design response surface experimental design.

  3. A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus

    Science.gov (United States)

    Vet, Robert; Artz, Richard S.; Carou, Silvina

    2014-08-01

    Investigating and assessing the chemical composition of precipitation and atmospheric deposition is essential to understanding how atmospheric pollutants contribute to contemporary environmental concerns including ecosystem acidification and eutrophication, loss of biodiversity, air pollution and global climate change. Evidence of the link between atmospheric deposition and these environmental issues is well established. The state of scientific understanding of this link is that present levels of atmospheric deposition of sulfur and nitrogen adversely affect terrestrial and aquatic ecosystems, putting forest sustainability and aquatic biodiversity at risk. Nitrogen and phosphorus loadings are linked to impacts on the diversity of terrestrial and aquatic vegetation through biological cycling, and atmospheric deposition plays a major role in the emission-transport-conversion-loss cycle of chemicals in the atmosphere as well as the formation of particulate matter and ozone in the troposphere. Evidence also shows that atmospheric constituents are changing the earth's climate through direct and indirect atmospheric processes. This Special Issue, comprising a single article titled "A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and pH, and phosphorus", presents a recent comprehensive review of precipitation chemistry and atmospheric deposition at global and regional scales. The information in the Special Issue, including all supporting data sets and maps, is anticipated to be of great value not only to the atmospheric deposition community but also to other science communities including those that study ecosystem impacts, human health effects, nutrient processing, climate change, global and hemispheric modeling and biogeochemical cycling. Understanding and quantifying pollutant loss from the atmosphere is, and will remain, an important component of each of these scientific fields as they

  4. Effects of sulphuric acid and acidifying ammonium deposition on water quality and vegetation of simulated soft water ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Schuurkes, J.A.A.R.; Heck, I.C.C; Hesen, P.L.G.M.; Leuven, R.S.E.W.; Roelofs, J.G.M.

    1986-11-01

    In a greenhouse, seven identical mini-ecosystems, simulating soft water ponds, were exposed to different types of artificial rain water. The effects of rain water containing H/sub 2/SO/sub 4/ and nitrate, and rain water containing ammonium sulphate on water quality and vegetation were studied and compared. Causal relations were established between rain water quality, water chemistry and changes in floristic composition. Ammonium sulphate deposition, particularly, strongly affected water quality and vegetation development. Although ammonium sulphate deposition was only slightly acid, due to nitrification it acted as an important acid source, causing acidification to pH 3.8. Under acidified conditions, ammonium sulphate deposition led to a luxuriant growth of Juncus bulbosus and Agrostis canina. In the mini-ecosystems, H/sub 2/SO/sub 4/ deposition with a pH of 3.5 only decreased the pH of the water to 5.1 within 1 yr, the acidification of water appeared to be coupled with changes in alkalinity, sulphate, Al, Cd, Ca, Mg, K and inorganic-N. It is concluded that in NH/sub 3/-affected regions in The Netherlands, the high atmospheric deposition of ammonium sulphate probably contributes to a large extent in the acidification, eutrophication and floristic changes of oligotrophic soft waters. 10 references.

  5. Supercritical synthesis and in situ deposition of PbS nanocrystals with oleic acid passivation for quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tavakoli, M.M. [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Simchi, A., E-mail: simchi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of); Aashuri, H. [Department of Materials Science and Engineering, Sharif University of Technology, 14588 Tehran (Iran, Islamic Republic of)

    2015-04-15

    Colloidal quantum dot solar cells have recently attracted significant attention due to their low-processing cost and surging photovoltaic performance. In this paper, a novel, reproducible, and simple solution-based process based on supercritical fluid toluene is presented for in situ growth and deposition PbS nanocrystals with oleic-acid passivation. A lead precursor containing sulfur was mixed with oleic acid in toluene and processed in a supercritical fluid condition at different temperatures of 140, 270 and 330 °C for 20 min. The quantum dots were deposited on a fluorine-doped tin oxide glass substrate inside the supercritical reactor. Transmission electron microscopy, X-ray diffraction, absorption and dynamic light scattering showed that the nanocrystals processed at the supercritical condition (330 °C) are fully crystalline with a narrow size distribution of ∼3 nm with an absorption wavelength of 915 nm (bandgap of 1.3 eV). Fourier transform infrared spectroscopy indicated that the PbS quantum dots are passivated by oleic acid molecules during the growth. Photovoltaic characteristics of Schottky junction solar cells showed an improvement over devices prepared by spin-coating. - Highlights: • Supercritical fluid processing and in situ deposition of PbS QDs are presented. • The prepared nanocrystals are mono-dispersed with an optical bandgap of 1.3 eV. • Photovoltaic performance of the in situ deposited nanocrystals is reported. • An improved PV performance compared to spin coated Schottky solar cells is shown.

  6. CYCLIC VOLTAMMETRY STUDIES OF COPPER (II) AND TELLURIUM (IV) IONS IN ACIDIC AQUEOUS SOLUTIONS FOR THIN FILM DEPOSITION

    OpenAIRE

    SARAVANAN NAGALINGAM; GEOK BEE TEH

    2014-01-01

    Cyclic voltammetry studies of copper (II) and tellurium (IV) ions in acidic aqueous solutions were carried out to determine the optimum condition for copper telluride thin film deposition. The voltammetry studies include reversible scans at different solution pH. Based on the voltammogram, suitable deposition conditions was determined to be in the range of -0.35 V to -0.45 V versus Ag/AgCl at pH values between 2.0 to 2.2 under non diffusion-limited conditions.

  7. CYCLIC VOLTAMMETRY STUDIES OF COPPER (II AND TELLURIUM (IV IONS IN ACIDIC AQUEOUS SOLUTIONS FOR THIN FILM DEPOSITION

    Directory of Open Access Journals (Sweden)

    SARAVANAN NAGALINGAM

    2014-05-01

    Full Text Available Cyclic voltammetry studies of copper (II and tellurium (IV ions in acidic aqueous solutions were carried out to determine the optimum condition for copper telluride thin film deposition. The voltammetry studies include reversible scans at different solution pH. Based on the voltammogram, suitable deposition conditions was determined to be in the range of -0.35 V to -0.45 V versus Ag/AgCl at pH values between 2.0 to 2.2 under non diffusion-limited conditions.

  8. Enhanced formic acid oxidation on polycrystalline platinum modified by spontaneous deposition of gold. Fourier transform infrared spectroscopy studies

    Science.gov (United States)

    Cappellari, Paula S.; García, Gonzalo; Florez-Montaño, Jonathan; Barbero, Cesar A.; Pastor, Elena; Planes, Gabriel A.

    2015-11-01

    Formic acid and adsorbed carbon monoxide electrooxidation on polycrystalline Pt and Au-modified Pt surfaces were studied by cyclic voltammetry, lineal sweep voltammetry and in-situ Fourier transform infrared spectroscopy techniques. With this purpose, a polycrystalline Pt electrode was modified by spontaneous deposition of gold atoms, achieving a gold surface coverage (θ) in the range of 0 ≤ θ ≤ 0.47. Results indicate the existence of two main pathways during the formic acid oxidation reaction, i.e. dehydration and dehydrogenation routes. At higher potentials than 0.5 V the dehydrogenation pathway appears to be the operative at both Pt and Au electrodes. Meanwhile, the dehydration reaction is the main pathway for Pt at lower potentials than 0.5 V. It was found that reaction routes are easily tuned by Au deposition on the Pt sites responsible for the formic acid dehydration reaction, and hence for the catalytic formation of adsorbed carbon monoxide. Gold deposition on these Pt open sites produces an enhanced activity toward the HCOOH oxidation reaction. In general terms, the surface inhibition of the reaction by adsorbed intermediates (indirect pathway) is almost absent at gold-modified Pt electrodes, and therefore the direct pathway appears as the main route during the formic acid electrooxidation reaction.

  9. Hyperspectral data for assessment of temporal changes in Norway spruce forest conditions in the mountainous region of the Czech Republic affected by long-term acidic deposition

    Science.gov (United States)

    Albrechtova, J.; Lhotakova, Z.; Misurec, J.; Kopackova, V.; Campbell, P. K. E.; Edwards-Jonasova, M.; Kupkova, L.; Cervena, L.; Potuckova, M.; Cudlin, P.

    2015-12-01

    The Ore Mts. located in the western part of the Czech Republic suffered during 1950's-1990´s heavy atmospheric pollution due to the mining activities and brown coal combustion. Acidic deposition in combination with harsh climatic conditions led there to large-scale forest decline. Although the load of SO2 has significantly decreased since 1991, tree damage was still visible in 1998 in terms of high defoliation or dead trees. Nowadays Norway spruce trees do not exhibit visible symptoms of damage but the full recovery of Norway spruce forests is not complete yet due to persisting adverse soil conditions. The temporal changes in the physiological status of Norway spruce forests in the Krušné Hory Mts. were evaluated using two sets of spectral images acquired in 1998 (ASAS) and in 2013 (APEX) and ground truth data (LAI, tree crown status, photosynthetic pigment contents, leaf spectral properties measured by spectroradiometer, soil properties - pH, contents of basic cations, heavy metals, etc.). Ground truth data were evaluated by unconstrained and constrained multivariate analyses using Canoco 5. The high resolution spectral images (ASAS and APEX) enabled the identification of a gradient of forest conditions and their comparison. In 1998 the stands exhibited different physiological status corresponding to the pollution gradient with healthier trees at the western part of the mountains. Analysis of the foliar chemistry in 2013 show a slight improvement of the Norway spruce physiological status in the eastern part of the mountains while the status of the western-located stands slightly worsened. In 2013 we also studied the differences in soil geochemical conditions, which appeared to be less favorable in the western part of the mountains characterized by a low base cation contents in the top organic horizon and a very low pH (pH<3).

  10. Electrodeposition of ruthenium, rhodium and palladium from nitric acid and ionic liquid media: Recovery and surface morphology of the deposits

    International Nuclear Information System (INIS)

    Research highlights: → Platinum group metals are man-made noble metals. → Electrochemical recovery of fission platinoids. → Recovery from nitric acid medium. → Recovery from ionic liquid medium. → Platinoids with exotic surface morphologies. - Abstract: Electrodeposition is a promising technique for the recovery of platinum group metals with unique surface morphologies. The electrodeposition of palladium, ruthenium and rhodium from aqueous nitric acid, and non-aqueous 1-butyl-3-methylimidazolium chloride ionic liquid medium was studied at stainless steel electrode. The surface morphology and elemental composition of the resultant deposit were probed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analysis. Deposits with diverse surface morphologies and metal compositions were obtained by varying the composition of the electrolytic medium and applied potential. The results demonstrate the possibility of tailoring the morphologies of PGMs by controlling the composition and potential needed for electrodeposition.

  11. Comparison among model estimates of critical loads of acidic deposition using different sources and scales of input data.

    Science.gov (United States)

    McDonnell, T C; Cosby, B J; Sullivan, T J; McNulty, S G; Cohen, E C

    2010-09-01

    The critical load (CL) of acidic atmospheric deposition represents the load of acidity deposited from the atmosphere to the earth's surface at which harmful acidification effects on sensitive biological receptors are thought to occur. In this study, the CL for forest soils was estimated for 27 watersheds throughout the United States using a steady-state mass balance approach based on both national and site-specific data and using different approaches for estimating base cation weathering. Results suggested that the scale and source of input data can have large effects on the calculated CL and that the most important parameter in the steady-state model used to estimate CL is base cation weathering. These results suggest that the data and approach used to estimate weathering must be robust if the calculated CL is to be useful for its intended purpose.

  12. Graphene decorated microelectrodes for simultaneous detection of ascorbic, dopamine, and folic acids by means of chemical vapor deposition

    Science.gov (United States)

    Namdar, N.; Hassanpour Amiri, M.; Dehghan Nayeri, F.; Gholizadeh, A.; Mohajerzadeh, S.

    2015-09-01

    In this paper, high quality and large area graphene layers were synthesized using thermal chemical vapour deposition on copper foil substrates. We use graphene incorporated electrodes to measure simultaneously ascorbic acid, dopamine and folic acid. Cyclic voltammetry and differential pulse voltammetry methods were used to evaluate electrochemical behaviour of the grown graphene layers. The graphene-modified electrode shows large electrochemical potential difference compared to bare gold electrodes with higher current responses. Also our fabricated electrodes configuration can be used easily for microfluidic analysis.

  13. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid

    Directory of Open Access Journals (Sweden)

    Loïc Assaud

    2014-02-01

    Full Text Available Three-dimensionally (3D nanoarchitectured palladium/nickel (Pd/Ni catalysts, which were prepared by atomic layer deposition (ALD on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4. Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects.

  14. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid.

    Science.gov (United States)

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit; Baranova, Elena A; Santinacci, Lionel

    2014-01-01

    Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects.

  15. Soil heavy metal contamination and acid deposition: experimental approach on two forest soils in Hunan, Southern China

    OpenAIRE

    Bo-han, Liao; Zhaohui, Guo; Probst, Anne; Probst, Jean-Luc

    2005-01-01

    In 1985, a tailing dam collapsed in Hunan province (southern China) leading to soil contamination by heavy metals from the tailings waste. Moreover, acid deposition becomes more and more serious in this area. In this context, two forest soils (a red soil and a yellow red soil, typically and commonly found in southern China) were collected from Hunan. The objectives are (i) to determine releases and changes in speciation fractions of heavy metals (especially Cd, Cu, and Zn) when the soils are ...

  16. Disruption of the transmembrane pH gradient--a possible mechanism for the antibacterial action of azelaic acid in Propionibacterium acnes and Staphylococcus epidermidis.

    Science.gov (United States)

    Bojar, R A; Cunliffe, W J; Holland, K T

    1994-09-01

    The effect of the topical acne treatment azelaic acid on the transmembrane proton gradient (delta pH) of Propionibacterium acnes and Staphylococcus epidermidis was studied in vitro at external pH values found on human skin (pH 4.0-6.0). Bacteria were grown in defined media using continuous culture and delta pH was estimated by measuring the accumulation of [14C] benzoic by the cells using flow dialysis. In both P. acnes and S. epidermidis the addition of 30 mM azelaic acid and the membrane active inhibitors nigericin (150 microM) and CCCP (150 microM) resulted in a rapid release of [14C] label into the dialysate indicating the dissipation of delta pH between external pH values of 4.0-6.0. The addition of 60 mM NaCl as an iso-osmotic control and 150 microM valinomycin did not induce the release of [14C] label. The addition of 30 mM azelaic acid reduced the delta pH of P. acnes by 44% at external pH 4.0 and 28% at external pH 6.0. In S. epidermidis 30 mM azelaic acid reduced delta pH by 88% at external pH 5.0 and 20% at external pH 6.0. Rapid loss of viability occurred in suspensions of P. acnes and S. epidermidis containing 30 mM azelaic acid at pH 4.0 with no viable cells recovered after 60 min incubation. At pH 6.0 little change in viable numbers of P. acnes and S. epidermidis were observed over a 2 h incubation period. The results indicate that the antibacterial activity of azelaic acid is associated with the perturbation of intracellular pH.

  17. Chapter 4. Uranium extraction technology from wastes of uranium industry. 4.1. Sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9

    International Nuclear Information System (INIS)

    Present article is devoted to sulfuric acid leaching kinetics of residues from anthropogenic deposit Map 1-9. Since residues from anthropogenic deposit Map 1-9 basically contain quartz (69%), it went through acid leaching. Results of laboratory investigations on the opening degree and uranium conversion to solution were summarized. The influence of sulfuric acid consumption on uranium extraction during leaching (U = 0,018%, t =20 deg C, t = 10 hours) was considered. The kinetic and energetic parameters of residues leaching of anthropogenic deposit Map 1-9 was discussed. The basic process flow diagram of uranium industry wastes reprocessing was proposed.

  18. Gradient networks

    Science.gov (United States)

    Toroczkai, Zoltán; Kozma, Balázs; Bassler, Kevin E.; Hengartner, N. W.; Korniss, G.

    2008-04-01

    Gradient networks are defined (Toroczkai and Bassler 2004 Nature 428 716) as directed graphs formed by local gradients of a scalar field distributed on the nodes of a substrate network G. We present the derivation for some of the general properties of gradient graphs and give an exact expression for the in-degree distribution R(l) of the gradient network when the substrate is a binomial (Erd{\\;\\kern -0.10em \\raise -0.35ex \\{{^{^{\\prime\\prime}}}}\\kern -0.57em \\o} s-Rényi) random graph, G_{N,p} , and the scalars are independent identically distributed (i.i.d.) random variables. We show that in the limit N \\to \\infty, p \\to 0, z = pN = \\mbox{const} \\gg 1, R(l)\\propto l^{-1} for l Bassler (2004 Nature 428 716).

  19. Acid Deposition Maps in Spain; Mapas de Deposito Acido en Espana

    Energy Technology Data Exchange (ETDEWEB)

    Artinano, B.; Cabal, H.; Garcia, C.

    1998-07-01

    Animal and monthly deposition velocity and total sulfur deposition maps have been performed for the peninsular Spain for 1992 by using the inferential method. To do this, updated databases with high space and time resolution, for land uses (CORINE) and meteorological information from analysis modelling for the same year, have been utilized. The final result are deposition maps in a 5x5 Km{sup 2} grid which allow to assess the methodology used in Europe to obtain the maps of excedances over the critical loads of pollutants. (Author) 32 refs.

  20. Acid Deposition Maps in Spain; Mapas de Deposito Acido en Espana

    Energy Technology Data Exchange (ETDEWEB)

    Artinano, B.; Cabal, H.; Garcia, C. [CIEMAT. Madrid (Spain)

    1998-12-31

    Annual and monthly deposition velocity and total sulfur deposition maps have been performed for the peninsular Spain for 1992 by using the inferential method. To de this, updated database with high space and time resolution, for land uses (CORINE) and meteorological information from analysis modelling for the same year, have been utilized. The final result are deposition maps in a 5 x 5 km``2 grid which allow to assess the methodology used in Europe to obtain the maps of excedance over the critical loads of pollutants. (Author) 32 refs.

  1. A Demonstration of Acid Rain and Lake Acidification: Wet Deposition of Sulfur Dioxide.

    Science.gov (United States)

    Goss, Lisa M.

    2003-01-01

    Introduces a science demonstration on the dissolution of sulfuric oxide emphasizing the concept of acid rain which is an environmental problem. Demonstrates the acidification from acid rain on two lake environments, limestone and granite. Includes safety information. (YDS)

  2. Metallothioneins (MTs) and {delta}-aminolevulinic acid dehydratase (ALAd) as biomarkers of metal pollution in great tits (Parus major) along a pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vanparys, Caroline [Laboratory of Ecophysiology, Biochemistry and Toxicology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)], E-mail: caroline.vanparys@ua.ac.be; Dauwe, Tom [Laboratory of Ethology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium); Campenhout, Karen van [Environment and Health, Flemish Government, Department of Environment, Nature and Energy, Koning Albert II-laan 20, bus 8, B-1000 Brussels (Belgium); Bervoets, Lieven; Coen, Wim de; Blust, Ronny [Laboratory of Ecophysiology, Biochemistry and Toxicology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Eens, Marcel [Laboratory of Ethology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium)

    2008-08-15

    Biomonitoring allows an integrated evaluation of different aspects of exposure, accumulation and effects to environmental pollution, simultaneously accounting for the natural variety between individuals in an ecosystem. In this study, the effects of increased metal accumulation were evaluated at the biochemical level in terms of two biomarker responses in the great tit (Parus major), a small insectivorous songbird, along an established metal pollution gradient. Metal concentrations in internal tissues (liver and kidney) and blood indicated that lead and cadmium were the most important metals in the pollution gradient under study. At the biochemical level, induction of metal binding protein metallothionein (MT) in liver and kidney reflected cadmium concentrations in these tissues (R{sup 2} = 0.42 and R{sup 2} = 0.94 respectively, n = 19), although in kidney, MT induction was not sufficient to complex all cadmium present. Secondly, the activity of the enzyme {delta}-aminolevulinic acid dehydratase (ALAd) in blood decreased exponentially in response to increased lead accumulation (R{sup 2} = 0.70, n = 18) and represents therefore a specific effect marker for lead exposure. In the highest polluted area, an ALAd inhibition of 85% was reported. Since a higher metal exposure resulted in an increased metal accumulation and subsequent biomarker responses in a dose-dependent way, this study indicates the applicability of ALAd and MT levels in great tits for biomonitoring responses to heavy metal pollution.

  3. Long-term development of acid deposition (1880?2030) in sensitive freshwater regions in Europe

    OpenAIRE

    Schöpp, W.; Posch, M.; Mylona, S.; M. Johansson

    2003-01-01

    International audience Time series of the deposition of acidifying substances are a pre-requisite for the study of the acidification and recovery of ecosystems such as surface waters. This paper reports the derivation and calculation of deposition trends of the potentially acidifying compounds SO2, NOx and NH3 in sensitive freshwater regions in Europe studied in the EU-funded RECOVER: 2010 project. The time interval covered is 151 years: from 1880, which can be considered as the pre-indust...

  4. Long-term development of acid deposition (1880–2030) in sensitive freshwater regions in Europe

    OpenAIRE

    Schöpp, W.; Posch, M.; Mylona, S.; M. Johansson

    2002-01-01

    Time series of the deposition of acidifying substances are a pre-requisite for the study of the acidification and recovery of ecosystems such as surface waters. This paper reports the derivation and calculation of deposition trends of the potentially acidifying compounds SO2, NOx and NH3 in sensitive freshwater regions in Europe studied in the EU-funded RECOVER: 2010 project. The time interval covered is 151 years: from 1880, which c...

  5. Controls on suppression of methane flux from a peat bog subjected to simulated acid rain sulfate deposition

    Science.gov (United States)

    Gauci, Vincent; Dise, Nancy; Fowler, David

    2002-01-01

    The effect of acid rain SO42- deposition on peatland CH4 emissions was examined by manipulating SO42- inputs to a pristine raised peat bog in northern Scotland. Weekly pulses of dissolved Na2SO4 were applied to the bog over two years in doses of 25, 50, and 100 kg S ha-1 yr-1, reflecting the range of pollutant S deposition loads experienced in acid rain-impacted regions of the world. CH4 fluxes were measured at regular intervals using a static chamber/gas chromatographic flame ionization detector method. Total emissions of CH4 were reduced by between 21 and 42% relative to controls, although no significant differences were observed between treatments. Estimated total annual fluxes during the second year of the experiment were 16.6 g m-2 from the controls and (in order of increasing SO42- dose size) 10.7, 13.2, and 9.8 g m-2 from the three SO42- treatments, respectively. The relative extent of CH4 flux suppression varied with changes in both peat temperature and peat water table with the largest suppression during cool periods and episodes of falling water table. Our findings suggest that low doses of SO42- at deposition rates commonly experienced in areas impacted by acid rain, may significantly affect CH4 emissions from wetlands in affected areas. We propose that SO42- from acid rain can stimulate sulfate-reducing bacteria into a population capable of outcompeting methanogens for substrates. We further propose that this microbially mediated interaction may have a significant current and future effect on the contribution of northern peatlands to the global methane budget.

  6. Preparation and evaluation of SiO2-deposited stearic acid-g-chitosan nanoparticles for doxorubicin delivery

    Directory of Open Access Journals (Sweden)

    Yuan H

    2012-09-01

    Full Text Available Hong Yuan, Xin Bao, Yong-Zhong Du, Jian You, Fu-Qiang HuCollege of Pharmaceutical Sciences, Zhejiang University, Hangzhou, PR ChinaPurpose: Both polymer micelles and mesoporous silica nanoparticles have been widely researched as vectors for small molecular insoluble drugs. To combine the advantages of copolymers and silica, studies on the preparation of copolymer-silica composites and cellular evaluation were carried out.Methods: First, a stearic acid-g-chitosan (CS-SA copolymer was synthesized through a coupling reaction, and then silicone oxide (SiO2-deposited doxorubicin (DOX-loaded stearic acid-g-chitosan (CS-SA/SiO2/DOX nanoparticles were prepared through the sol-gel reaction. Physical and chemical properties such as particle size, zeta potential, and morphologies were examined, and small-angle X-ray scattering (SAXS analysis was employed to identify the mesoporous structures of the generated nanoparticles. Cellular uptake and cytotoxicity studies were also conducted.Results: CS-SA/SiO2/DOX nanoparticles with different amounts of SiO2 deposited were obtained, and SAXS studies showed that mesoporous structures existed in the CS-SA/SiO2/DOX nanoparticles. The mesoporous size of middle-ratio and high-ratio deposited CS-SA/SiO2/DOX nanoparticles were 4–5 nm and 8–10 nm, respectively. Based on transmission electron microscopy images of CS-SA/SiO2/DOX nanoparticles, dark rings around the nanoparticles could be observed in contrast with CS-SA/DOX micelles. Furthermore, CS-SA/SiO2/DOX nanoparticles exhibited faster release behavior in vitro than CS-SA/DOX micelles; cellular uptake research in A549 indicated that the CS-SA/SiO2/DOX nanoparticles were taken up by A549 cells more rapidly, and that CS-SA/SiO2/DOX nanoparticles entered the cell more easily when the amount of SiO2 was higher. IC50 values of CS-SA/DOX micelles, CS-SA/SiO2/DOX-4, CS-SA/SiO2/DOX-8, and CS-SA/SiO2/DOX-16 nanoparticles against A549 cells measured using the MTT assay were

  7. Stearic acids at sn-1, 3 positions of TAG are more efficient at limiting fat deposition than palmitic and oleic acids in C57BL/6 mice.

    Science.gov (United States)

    Gouk, Shiou-Wah; Cheng, Sit-Foon; Ong, Augustine Soon-Hock; Chuah, Cheng-Hock

    2014-04-14

    In the present study, we investigated the effect of long-acyl chain SFA, namely palmitic acid (16:0) and stearic acid (18:0), at sn-1, 3 positions of TAG on obesity. Throughout the 15 weeks of the experimental period, C57BL/6 mice were fed diets fortified with cocoa butter, sal stearin (SAL), palm mid fraction (PMF) and high-oleic sunflower oil (HOS). The sn-1, 3 positions were varied by 16:0, 18:0 and 18:1, whilst the sn-2 position was preserved with 18:1. The HOS-enriched diet was found to lead to the highest fat deposition. This was in accordance with our previous postulation. Upon normalisation of total fat deposited with food intake to obtain the fat:feed ratio, interestingly, mice fed the SAL-enriched diet exhibited significantly lower visceral fat/feed and total fat/feed compared with those fed the PMF-enriched diet, despite their similarity in SFA-unsaturated fatty acid-SFA profile. That long-chain SFA at sn-1, 3 positions concomitantly with an unsaturated FA at the sn-2 position exert an obesity-reducing effect was further validated. The present study is the first of its kind to demonstrate that SFA of different chain lengths at sn-1, 3 positions exert profound effects on fat accretion.

  8. Critical loads for deposition of acid and nitrogen - do we know enough to make the concept useful?

    International Nuclear Information System (INIS)

    Critical loads for acid deposition of sulphur and nitrogen compounds are useful concepts related to the rate of weathering of primary minerals or to the rate of changes in secondary minerals, as these processes are the most important counteracting processes in a long-term perspective. As nitrogen saturation seldom occurs over large areas in nature, the dominant producers in forest ecosystems, the trees, as well as most of their associated organisms, are not evolutionarily adapted to nitrogen saturation. Large environmental changes will be the consequence of present nitrogen enrichment in regions with high nitrogen deposition. It is a real challenge for the scientific community to define critical loads for different sites, and to inform the public on the consequences of present environmental policies in different countries. (orig./VT)

  9. Modelling the effects of acid deposition: refinements, adjustments and inclusion of nitrogen dynamics in the MAGIC model

    Directory of Open Access Journals (Sweden)

    B. J. Cosby

    2001-01-01

    Full Text Available The MAGIC model of the responses of catchments to acidic deposition has been applied and tested extensively over a 15 year period at many sites and in many regions around the world. Overall, the model has proven to be robust, reliable and useful in a variety of scientific and managerial activities. Over the years, several refinements and additions to MAGIC have been proposed and/or implemented for particular applications. These adjustments to the model structure have all been included in a new version of the model (MAGIC7. The log aluminium – pH relationship now does not have to be fixed to aluminium trihydroxide solubility. Buffering by organic acids using a triprotic analog is now included. Dynamics of nitrogen retention and loss in catchments can now be linked to soil nitrogen and carbon pools. Simulation of short-term episodic response by mixing fractions of different water types is also possible. This paper presents a review of the conceptual structure of MAGIC7 relating to long-term simulation of acidification and recovery, describes the conceptual basis of the new nitrogen dynamics and provides a comprehensive update of the equations, variables, parameters and inputs for the model. Keywords: process-based model, acid deposition, recovery

  10. Diversity and Distribution of Arsenic-Related Genes Along a Pollution Gradient in a River Affected by Acid Mine Drainage.

    Science.gov (United States)

    Desoeuvre, Angélique; Casiot, Corinne; Héry, Marina

    2016-04-01

    Some microorganisms have the capacity to interact with arsenic through resistance or metabolic processes. Their activities contribute to the fate of arsenic in contaminated ecosystems. To investigate the genetic potential involved in these interactions in a zone of confluence between a pristine river and an arsenic-rich acid mine drainage, we explored the diversity of marker genes for arsenic resistance (arsB, acr3.1, acr3.2), methylation (arsM), and respiration (arrA) in waters characterized by contrasted concentrations of metallic elements (including arsenic) and pH. While arsB-carrying bacteria were representative of pristine waters, Acr3 proteins may confer to generalist bacteria the capacity to cope with an increase of contamination. arsM showed an unexpected wide distribution, suggesting biomethylation may impact arsenic fate in contaminated aquatic ecosystems. arrA gene survey suggested that only specialist microorganisms (adapted to moderately or extremely contaminated environments) have the capacity to respire arsenate. Their distribution, modulated by water chemistry, attested the specialist nature of the arsenate respirers. This is the first report of the impact of an acid mine drainage on the diversity and distribution of arsenic (As)-related genes in river waters. The fate of arsenic in this ecosystem is probably under the influence of the abundance and activity of specific microbial populations involved in different As biotransformations. PMID:26603631

  11. Long-term development of acid deposition (1880–2030) in sensitive freshwater regions in Europe

    OpenAIRE

    Schöpp, W.; Posch, M.; Mylona, S.; M. Johansson

    2003-01-01

    Time series of the deposition of acidifying substances are a pre-requisite for the study of the acidification and recovery of ecosystems such as surface waters. This paper reports the derivation and calculation of deposition trends of the potentially acidifying compounds SO2, NOx and NH3 in sensitive freshwater regions in Europe studied in the EU-funded RECOVER: 2010 project. The time interval covered is 151 years: from 1880, which can be considered as the pre-industrial era in mo...

  12. Gradient Acid Dissolving Test Study and Identification of Geopolymer and Cement Hydration Products%梯度酸溶法区分地聚合物与水泥水化产物

    Institute of Scientific and Technical Information of China (English)

    郭晓潞; 施惠生; 林茂松

    2013-01-01

    Gradient acid dissolving tests were made to divide geopolymer and hydration product quantificationally.The feasibility of gradient acid dissolving test was investigated on the basis of the dissolution rates of geopolymer/hydration product and X-Ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR) analyses.The results show the behaviors of dissolution of the geopolymer and the hydration product in the same gradient acid are different, and the acid point to divide geopolymer and hydration product is pH = 3.The gradient acid dissolving test is an effective method to divide geopolymer and hydration product.%采用梯度酸溶解试验方法来定量区分地聚合物与普通水化产物,结合产物溶解率与残渣微观分析验证了该方法的可行性.研究结果表明,地聚合物与普通水化产物在梯度酸中的酸溶性存在较大差异,区分地聚合物与普通水化产物的酸临界点为pH=3,梯度酸溶解试验能较好地区分两者.

  13. Isotope and fatty acid trends along continental shelf depth gradients: Inshore versus offshore hydrological influences on benthic trophic functioning

    Science.gov (United States)

    Chouvelon, T.; Schaal, G.; Grall, J.; Pernet, F.; Perdriau, M.; A-Pernet, E. J.; Le Bris, H.

    2015-11-01

    Anthropogenic activities and land-based inputs into the sea may influence the trophic structure and functioning of coastal and continental shelf ecosystems, despite the numerous opportunities and services the latter offer to humans and wildlife. In addition, hydrological structures and physical dynamics potentially influence the sources of organic matter (e.g., terrestrial versus marine, or fresh material versus detrital material) entering marine food webs. Understanding the significance of the processes that influence marine food webs and ecosystems (e.g., terrestrial inputs, physical dynamics) is crucially important because trophic dynamics are a vital part of ecosystem integrity. This can be achieved by identifying organic matter sources that enter food webs along inshore-offshore transects. We hypothesised that regional hydrological structures over wide continental shelves directly control the benthic trophic functioning across the shelf. We investigated this issue along two transects in the northern ecosystem of the Bay of Biscay (north-eastern Atlantic). Carbon and nitrogen stable isotope analysis (SIA) and fatty acid analysis (FAA) were conducted on different complementary ecosystem compartments that include suspended particulate organic matter (POM), sedimentary organic matter (SOM), and benthic consumers such as bivalves, large crustaceans and demersal fish. Samples were collected from inshore shallow waters (at ∼1 m in depth) to more than 200 m in depth on the offshore shelf break. Results indicated strong discrepancies in stable isotope (SI) and fatty acid (FA) compositions in the sampled compartments between inshore and offshore areas, although nitrogen SI (δ15N) and FA trends were similar along both transects. Offshore the influence of a permanently stratified area (described previously as a "cold pool") was evident in both transects. The influence of this hydrological structure on benthic trophic functioning (i.e., on the food sources available for

  14. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  15. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  16. Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Shilei; Wang, Yazhou; Wang, Bochu, E-mail: wangbc2000@126.com; Deng, Jia; Zhu, Liancai; Cao, Yang

    2014-06-01

    In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery. - Highlights: • The porous PLGA microparticles were successfully prepared by the electrospray deposition method at one step. • The porous microparticles had high loading capacity and low density. • The microparticle showed a sustained release in the simulated gastric liquid. • The microparticles showed a slight cytotoxicity in vitro.

  17. Preliminary assessment of the current impact and potential risk of acidic deposition on walleye populations in Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Wales, D.L.; Liimatainen, V.A.

    1987-01-01

    Netting survey and field bioassay data were used to determine a pH threshold for survival of walleye. Established pH thresholds were then used to assess the current impact and potential risk of acidic deposition on walleye populations in Ontario. Extinction of walleye appeared to occur in lakes with pH < 5.5. Some losses may also have occurred in lakes with pH 5.5-6.0. An estimated 0.3% (number of lakes (N)=12) of the Ontario walleye lakes currently have pH < 5.5 and have likely lost walleye populations. A further 1.5% (N=60) of the lakes have pH 5.5-6.0 and may show signs of acidification stress. An estimated 2.0% (N=79) of the province's walleye lakes have very low alkalinities (0.0-2.0 mg/l) and are classified as extremely sensitive to continued high deposition of acidic precipitation. 19 refs., 4 figs., 7 tabs.

  18. Differentiation between focal malignant marrow-replacing lesions and benign red marrow deposition of the spine with T2{sup *}-corrected fat-signal fraction map using a three -echo volume interpolated breath-hold gradient echo dixon sequence

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong Pyo; Kim, Sung Jun; Chung, Tae Sub; Yoo, Yeon Hwa; Yoon, Choon Sik [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kanneengiesser, Stephan [MR Applications Development, Siemens AG, Healthcare Sector, Erlangen (Germany); Paek, Moon Young [Siemens Ltd., Seoul (Korea, Republic of); Song, Ho Taek; Lee, Young Han; Suh, Jin Suck [Dept. of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-12-15

    To assess the feasibility of T2{sup *}-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. Fat-signal fraction measurement using T2{sup *}-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.

  19. Biomimetic Deposition of Hydroxyapatite by Mixed Acid Treatment of Titanium Surfaces.

    Science.gov (United States)

    Zhao, J M; Park, W U; Hwang, K H; Lee, J K; Yoon, S Y

    2015-03-01

    A simple chemical method was established for inducing bioactivity of Ti metal. In the present study, two kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coatings successfully formed on the Ti surfaces in the simulated body fluid. Strong mixed acid etching was used to increase the roughness of the metal surface, because the porous and rough surfaces allow better adhesion between Ca-P coatings and substrate. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Some specimens were treated with a 5 M NaOH aqueous solution, and then heat treated at 600 °C in order to form an amorphous sodium titanate layer on their surface. This treated titanium metal is believed to form a dense and uniform bone-like apatite layer on its surface in a simulated body fluid (SBF). This study proved that mixed acid treatment is not only important for surface passivation but is also another bioactive treatment for titanium surfaces, an alternative to alkali treatment. In addition, mixed acid treatment uses a lower temperature and shorter time period than alkali treatment. PMID:26413704

  20. Suppression of fat deposition in broiler chickens by (-)-hydroxycitric acid supplementation: A proteomics perspective

    Science.gov (United States)

    Peng, Mengling; Han, Jing; Li, Longlong; Ma, Haitian

    2016-01-01

    (-)-Hydroxycitric acid (HCA) suppresses fatty acid synthesis in animals, but its biochemical mechanism in poultry is unclear. This study identified the key proteins associated with fat metabolism and elucidated the biochemical mechanism of (-)-HCA in broiler chickens. Four groups (n = 30 each) received a diet supplemented with 0, 1000, 2000 or 3000 mg/kg (-)-HCA for 4 weeks. Of the differentially expressed liver proteins, 40 and 26 were identified in the mitochondrial and cytoplasm respectively. Pyruvate dehydrogenase E1 components (PDHA1 and PDHB), dihydrolipoyl dehydrogenase (DLD), aconitase (ACO2), a-ketoglutarate dehydrogenase complex (DLST), enoyl-CoA hydratase (ECHS1) and phosphoglycerate kinase (PGK) were upregulated, while NADP-dependent malic enzyme (ME1) was downregulated. Biological network analysis showed that the identified proteins were involved in glycometabolism and lipid metabolism, whereas PDHA1, PDHB, ECHS1, and ME1 were identified in the canonical pathway by Ingenuity Pathway Analysis. The data indicated that (-)-HCA inhibited fatty acid synthesis by reducing the acetyl-CoA supply, via promotion of the tricarboxylic acid cycle (upregulation of PDHA1, PDHB, ACO2, and DLST expression) and inhibition of ME1 expression. Moreover, (-)-HCA promoted fatty acid beta-oxidation by upregulating ECHS1 expression. These results reflect a biochemically relevant mechanism of fat reduction by (-)-HCA in broiler chickens. PMID:27586962

  1. Suppression of fat deposition in broiler chickens by (-)-hydroxycitric acid supplementation: A proteomics perspective.

    Science.gov (United States)

    Peng, Mengling; Han, Jing; Li, Longlong; Ma, Haitian

    2016-01-01

    (-)-Hydroxycitric acid (HCA) suppresses fatty acid synthesis in animals, but its biochemical mechanism in poultry is unclear. This study identified the key proteins associated with fat metabolism and elucidated the biochemical mechanism of (-)-HCA in broiler chickens. Four groups (n = 30 each) received a diet supplemented with 0, 1000, 2000 or 3000 mg/kg (-)-HCA for 4 weeks. Of the differentially expressed liver proteins, 40 and 26 were identified in the mitochondrial and cytoplasm respectively. Pyruvate dehydrogenase E1 components (PDHA1 and PDHB), dihydrolipoyl dehydrogenase (DLD), aconitase (ACO2), a-ketoglutarate dehydrogenase complex (DLST), enoyl-CoA hydratase (ECHS1) and phosphoglycerate kinase (PGK) were upregulated, while NADP-dependent malic enzyme (ME1) was downregulated. Biological network analysis showed that the identified proteins were involved in glycometabolism and lipid metabolism, whereas PDHA1, PDHB, ECHS1, and ME1 were identified in the canonical pathway by Ingenuity Pathway Analysis. The data indicated that (-)-HCA inhibited fatty acid synthesis by reducing the acetyl-CoA supply, via promotion of the tricarboxylic acid cycle (upregulation of PDHA1, PDHB, ACO2, and DLST expression) and inhibition of ME1 expression. Moreover, (-)-HCA promoted fatty acid beta-oxidation by upregulating ECHS1 expression. These results reflect a biochemically relevant mechanism of fat reduction by (-)-HCA in broiler chickens. PMID:27586962

  2. Suppression of fat deposition in broiler chickens by (-)-hydroxycitric acid supplementation: A proteomics perspective

    Science.gov (United States)

    Peng, Mengling; Han, Jing; Li, Longlong; Ma, Haitian

    2016-09-01

    (-)-Hydroxycitric acid (HCA) suppresses fatty acid synthesis in animals, but its biochemical mechanism in poultry is unclear. This study identified the key proteins associated with fat metabolism and elucidated the biochemical mechanism of (-)-HCA in broiler chickens. Four groups (n = 30 each) received a diet supplemented with 0, 1000, 2000 or 3000 mg/kg (-)-HCA for 4 weeks. Of the differentially expressed liver proteins, 40 and 26 were identified in the mitochondrial and cytoplasm respectively. Pyruvate dehydrogenase E1 components (PDHA1 and PDHB), dihydrolipoyl dehydrogenase (DLD), aconitase (ACO2), a-ketoglutarate dehydrogenase complex (DLST), enoyl-CoA hydratase (ECHS1) and phosphoglycerate kinase (PGK) were upregulated, while NADP-dependent malic enzyme (ME1) was downregulated. Biological network analysis showed that the identified proteins were involved in glycometabolism and lipid metabolism, whereas PDHA1, PDHB, ECHS1, and ME1 were identified in the canonical pathway by Ingenuity Pathway Analysis. The data indicated that (-)-HCA inhibited fatty acid synthesis by reducing the acetyl-CoA supply, via promotion of the tricarboxylic acid cycle (upregulation of PDHA1, PDHB, ACO2, and DLST expression) and inhibition of ME1 expression. Moreover, (-)-HCA promoted fatty acid beta-oxidation by upregulating ECHS1 expression. These results reflect a biochemically relevant mechanism of fat reduction by (-)-HCA in broiler chickens.

  3. Nitrogen deposition threatens species richness of grasslands across Europe

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C.J. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Gowing, D.J.G. [Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Dupre, C.; Diekmann, M. [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Dorland, E. [Section of Landscape Ecology, Department of Geobiology, Utrecht University, P.O. Box 80084, 3508 TB Utrecht (Netherlands); Gaudnik, C.; Alard, D.; Corcket, E. [University of Bordeaux 1. UMR INRA 1202 Biodiversity, Genes and Communities, Equipe Ecologie des Communautes, Batiment B8 - Avenue des Facultes, F-33405 Talence (France); Bleeker, A. [Department of Air Quality and Climate Change, Energy Research Centre of the Netherlands, P.O. Box 1, 1755 ZG Petten (Netherlands); Bobbink, R. [B-WARE Research Centre, Radboud University, P.O. Box 9010, 6525 ED Nijmegen (Netherlands); Fowler, D. [NERC Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB (United Kingdom); Mountford, J.O. [NERC Centre for Ecology and Hydrology, MacLean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB (United Kingdom); Vandvik, V. [Department of Biology, University of Bergen, Box 7800, N-5020 Bergen (Norway); Aarrestad, P.A. [Norwegian Institute for Nature Research, NO-7485 Trondheim (Norway); Muller, S. [Laboratoire des Interactions Ecotoxicologie, Biodiversite et Ecosystemes LIEBE, UMR CNRS 7146, U.F.R. Sci. F.A., Campus Bridoux, Universite Paul Verlaine, Avenue du General Delestraint, F-57070 Metz (France); Dise, N.B. [Department of Environmental and Geographical Science, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2010-09-15

    Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha{sup -1} yr{sup -1}) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range. Atmospheric nitrogen deposition is reducing biodiversity in grasslands across Europe.

  4. Nitrogen deposition threatens species richness of grasslands across Europe

    International Nuclear Information System (INIS)

    Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha-1 yr-1) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range. Atmospheric nitrogen deposition is reducing biodiversity in grasslands across Europe.

  5. Effect of acid deposition on Nanshan forest at Chongging in China

    International Nuclear Information System (INIS)

    Chongqing is the city where atmospheric pollution is severest in China, and the pH of rainwater has been measured every year since 1981, which is close to 4.0 now. In 1982, the decline of Pinus massoniana in Nanshan district in southeast Chongqing has occurred. The decline phenomena of this forest attracted attention also in foreign countries, and the various studies on its causes have been carried out, consequently, the main cause was presumed to be the compound effect of acid rain, acid mist and the damage by insects. It was clarified by the recent research that the dry and wet acid fallouts mainly composed of SO2 are one of the important causes that brought about the decline of Pinus massoniana in Nanshan. The forest area in Nanshan is about 2000 ha, and almost the simple forest of Pinus massoniana that distributes at the elevation from 400 to 1400 m. The withering of a small number began to occur in 1982, but thereafter, the area of withering increased rapidly, and reached 41.8% of the total forest area in July, 1983. The decline still continues now. The direct effect of acid fallout to Nanshan forest and the indirect effect through soil are reported in this paper. (K.I.)

  6. Phytopigments and fatty acids in the gut of the deposit-feeding heart urchin

    NARCIS (Netherlands)

    Boon, A.R.; Duineveld, G.C.A.

    2012-01-01

    As part of a broader study on benthic–pelagic coupling in the southern North Sea, specimens of the common heart urchin Echinocardium cordatum were sampled for analyses on phytopigments and fatty acids in their guts. Results were interpreted in the context of feeding and ecological functioni

  7. ELECTROCHEMICALLY DEPOSITED POLYMER-COATED GOLD ELECTRODES SELECTIVE FOR 2,4-DICHLOROPHENOXYACETIC ACID

    Science.gov (United States)

    Electropolymerized membranes on gold electrodes doped with 2,4-dichlorophenoxyacetic acid (2,4-D) were prepared from a solution containing resorcinol, o-phenylenediamine and 2,4-D. Fourier Transform Infrared (FTIR) spectroscopy was used to evaluate the incorporation and interact...

  8. Groundtruthing and potential for predicting acid deposition impacts in headwater streams using bedrock geology, GIS, angling, and stream chemistry.

    Science.gov (United States)

    Kirby, C S; McInerney, B; Turner, M D

    2008-04-15

    Atmospheric acid deposition is of environmental concern worldwide, and the determination of impacts in remote areas can be problematic. Rainwater in central Pennsylvania, USA, has a mean pH of approximately 4.4. Bedrock varies dramatically in its ability to neutralize acidity. A GIS database simplified reconnaissance of non-carbonate bedrock streams in the Valley and Ridge Province and identified potentially chronically impacted headwater streams, which were sampled for chemistry and brook trout. Stream sites (n=26) that originate in and flow through the Tuscarora had a median pH of 5.0 that was significantly different from other formations. Shawangunk streams (n=6) and non-Tuscarora streams (n=20) had a median pH of 6.0 and 6.3, respectively. Mean alkalinity for non-Tuscarora streams (2.6 mg/L CaCO(3)) was higher than the mean for Tuscarora streams (0.5 mg/L). Lower pH and alkalinity suggest that the buffering capability of the Tuscarora is inferior to that of adjacent sandstones. Dissolved aluminum concentrations were much higher for Tuscarora streams (0.2 mg/L; approximately the lethal limit for brook trout) than for non-Tuscarora streams (0.03 mg/L) or Shawangunk streams (0.02 mg/L). Hook-and-line methods determined the presence/absence of brook trout in 47 stream reaches with suitable habitat. Brook trout were observed in 21 of 22 non-Tuscarora streams, all 6 Shawangunk streams, and only 9 of 28 Tuscarora stream sites. Carefully-designed hook-and-line sampling can determine the presence or absence of brook trout and help confirm biological impacts of acid deposition. 15% of 334 km of Tuscarora stream lengths are listed as "impaired" due to atmospheric deposition by the Pennsylvania Department of Environmental Protection. 65% of the 101 km of Tuscarora stream lengths examined in this study were impaired. PMID:18258282

  9. Determination of in situ speciation of manganese in treated acid mine drainage water by using multiple diffusive gradients in thin films devices

    Energy Technology Data Exchange (ETDEWEB)

    Lopes F de Oliveira, Rodrigo; Pedrobom, Jorge H. [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Menegário, Amauri A., E-mail: amenega@rc.unesp.br [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Domingos, Roberto N. [Centro de Estudos Ambientais - CEA, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil); Py, Delcy A. [INB - Indústrias Nucleares do Brasil, Estrada Poços – Andradas Km 20,6, CEP 37780-000 Caldas, MG (Brazil); Kiang, Chang Hung [Laboratório de Estudos de Bacias - LEBAC, Instituto de Geociências e Ciências Exatas - IGCE, UNESP - Universidade Estadual Paulista, Avenida 24-A, 1515, CEP 13506-900 Rio Claro, SP (Brazil)

    2013-10-17

    Graphical abstract: -- Highlights: •In situ speciation of Mn by using multiple DGT devices was evaluated. •Chelex resin, DE81 and P81 membranes were used as binding phases in the DGT devices. •The proposed approach was applied to analyze treated acid mine drainage. •Good results were found for speciation of Mn in site containing <40 mg Ca L{sup −1}. DGT speciation were in agreement with speciation by software and by on site SPE. -- Abstract: Acid mine drainage (AMD) is a serious environmental problem that creates acidic solution with high Mn concentrations. The speciation of residual Mn from AMD after an active treatment involving the addition of a neutralizing agent can reliably evaluate the treatment efficiency and provide knowledge of the Mn species being inputted into the environment. The aim of this study was to evaluate the in situ lability and speciation of Mn using the diffusive gradients in thin films (DGT) technique with treated drainage water from a uranium mine (TAMD). DGT devices with different binding phases (Chelex-100 and P81 and DE81membranes) were used to perform the in situ speciation of Mn. A comparison of the results from deploying DGT in the laboratory and in situ shows that the speciation of Mn in TAMD should be performed in situ. Linear deployment curves (from in situ experiments) indicate that the DGT device containing the Chelex-100 binding phase can be used to evaluate Mn lability in TAMD. The labile Mn fraction (from in situ measurements) obtained using the device containing the Chelex-100 resin ranged from 63 to 81% of the total Mn concentration and, when compared to the speciation obtained using the CHEAQS software, indicated that this device was capable of uptaking the free Mn{sup 2+} and a portion of the MnSO{sub 4(aq)}. The values obtained using the DGT technique were compared to those from on site solid phase extraction, and a good agreement was found between the results. The amount of negative Mn species sampled by DE81

  10. Enhancement of supercapacitance property of electrochemically deposited MnO2 thin films grown in acidic medium

    Science.gov (United States)

    Jana, S. K.; Rao, V. P.; Banerjee, S.

    2014-02-01

    In this communication we present supercapacitance property of MnO2 thin-films which are fabricated on stainless steel (SS) substrate by electro-deposition method carried out in different pH of the electrolyte. A significant improvement of the device performance of acid mediated grown (AMG) MnO2 over normal MnO2 (grown in neutral medium) has been achieved. We have also investigated role of interfacial structure on the internal resistance of the device material. AMG MnO2 film exhibits superior device performance with specific capacitance of 652 F/g which is 2 times better than that obtained in normal MnO2 and also energy density of 90.69 Wh/kg.

  11. Lipids in grain tissues of oat (Avena sativa): differences in content, time of deposition, and fatty acid composition.

    Science.gov (United States)

    Banas, Antoni; Debski, Henryk; Banas, Walentyna; Heneen, Waheeb K; Dahlqvist, Anders; Bafor, Maureen; Gummeson, Per-Olov; Marttila, Salla; Ekman, Asa; Carlsson, Anders S; Stymne, Sten

    2007-01-01

    Oat (Avena sativa) is unusual in comparison with other cereals since there are varieties with up to 18% oil content. The lipid content and fatty acid composition in different parts of the grain during seed development were characterized in cultivars Freja (6% oil) and Matilda (10% oil), using thin-layer and gas chromatography, and light and electron microscopy. The majority of lipids (86-90%) were found in the endosperm. Ninety-five per cent of the higher oil content of cv. Matilda compared with cv. Freja was due to increased oil content of the endosperm. Up to 84% of the lipids were deposited during the first half of seed development, when seeds where still green with a milky endosperm. Microscopy studies revealed that whereas oil bodies of the embryo and scutellum still contained a discrete shape upon grain maturation, oil bodies of the endosperms fused upon maturation and formed smears of oil.

  12. Different responses of two Mosla species to potassium limitation in relation to acid rain deposition

    Institute of Scientific and Technical Information of China (English)

    Meng WANG; Bao-jing GU; Ying GE; Zhen LIU; De-an JIANG; Scott X. CHANG; Jie CHANG

    2009-01-01

    The increasingly serious problem of acid rain is leading to increased potassium (K) loss from soils, and in our field investigation, we found that even congenerically relative Mosla species show different tolerance to K-deficiency. A hydroponic study was conducted on the growth of two Mosla species and their morphological, physiological and stoichiometric traits in response to limited (0.35 mmol K/L), normal (3.25 mmol K/L) and excessive (6.50 mmol K/L) K concentrations. Mosla hang-chowensis is an endangered plant, whereas Mosla dianthera a widespread weed. In the case of M. hangchowensis, in comparison with normal K concentration, K-limitation induced a significant reduction in net photosynthetic rate (Pn), soluble protein content, and superoxide dismutase (SOD) activity, but an increase in malondialdehyde (MDA) concentration. However, leaf mass ratio (LMR) and root mass ratio (RMR) were changed little by K-limitation. In contrast, for M. dianthera, K-limitation had little effect on Pn, soluble protein content, SOD activity, and MDA concentration, but increased LMR and RMR. Critical values of N (nitrogen):K and K:P (phosphorus) ratios in the shoots indicated that limitation in acquiring K occurred under K-limited conditions for M. hangchowensis but not for M. dianthera. We found that low K content in natural habitats was a restrictive factor in the growth and distribution of M. hangchowensis, and soil K-deficiency caused by acid rain worsened the situation of M. hangchowensis, while M. dianthera could well acclimate to the increasing K-deficiency. We suggest that controlling the acid rain and applying K fertilizers may be an effective way to rescue the endangered M. hangchowensis.

  13. An Adirondack Watershed Data Base: Attribute and mapping information for regional acidic deposition studies

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, A.E.; Olson, R.J.; Gruendling, G.K.; Bogucki, D.J.; Malanchuk, J.L.; Durfee, R.C.; Turner, R.S.; Adams, K.B.; Wilson, D.L.; Coleman, P.R.

    1988-12-01

    The Adirondack Watershed Data Base (AWDB) provides a means to test hypotheses concerning the relative importance of various watershed attributes that may contribute to increased acidification of Adirondack surface waters. The AWDB is a valuable resource for the study of other ecological phenomena. The AWDB consists of digital watershed boundaries and digital geographic data, stored within a geographic information system, and watershed/lake attribute data stored in a data management system (SAS) for 463 Adirondack headwater lakes. Attributes include watershed morphology, physiography, bedrock, soils, land cover, wetlands, disturbances (e.g., cabins, fire, and logging), beaver activity, precipitation, and atmospheric deposition. Over 600 variables are available for each watershed. These data can be combined with water chemistry data and fish community status for regional-scale examinations of watershed attributes that may account for variability and change in water chemistry and fish populations in the Adirondacks. This report describes the design of the AWDB, documents sources and history of the data; defines the format of the AWDB contents; and characterizes the data using summary statistics, frequency bar charts, and other graphics. In addition, it provides information necessary for researchers using the data base on their own computer systems. 37 refs., 42 figs., 4 tabs.

  14. Responses of streams in central Appalachian Mountain region to reduced acidic deposition--comparisons with other regions in North America and Europe.

    Science.gov (United States)

    Chen, Yushun; Lin, Lian-Shin

    2009-03-15

    Data from 5 wet deposition stations and 21 streams during 1980-2006 were analyzed to investigate chemical responses of streams to reduced acidic deposition in the central Appalachian Mountain region of West Virginia, USA. Wet deposition of acidic anions (i.e., sulfate, nitrate, and chloride) and hydrogen ions decreased significantly during the studied time period. Stream sulfate showed a delayed response to the reduced acidic deposition, and showed a decrease in the 2000s (-5.54 microeq L(-1) yr(-1)) and the whole period (-0.49 microeq L(-1) yr(-1)). No significant trend of stream nitrate+nitrite and chloride was observed. Stream alkalinity increased in the 1990s (+23.33 microeq L(-1) yr(-1)) and the whole period (+7.26 microeq L(-1) yr(-1)). Stream hydrogen ions decreased in the 1990s (-0.002 microeq L(-1) yr(-1)), 2000s (-0.001 microeq L(-1) yr(-1)), and the whole period (-0.001 microeq L(-1) yr(-1)). Compared with most acidic streams and lakes in the United States and Europe, a lower decreasing rate of hydrogen ions and higher increasing rate of alkalinity were observed in the alkaline West Virginian streams in the 1990s. However, due to their initial negative or zero alkalinity values, those acidic streams showed a higher percent increase in alkalinity than that in the alkaline West Virginian streams (from 800 microeq L(-1) yr(-1) to 1200 microeq L(-1) yr(-1)). Total aluminum in the West Virginian streams decreased in the 1990s (-0.67 micromol L(-1) yr(-1)) and the whole period (-0.22 micromol L(-1) yr(-1)). The current study advanced our understanding of streams' responses to the reduced acidic deposition in the Mid-Appalachians since the passage of the 1970 and 1990 Amendments to the United States Clean Air Act (US CAAA).

  15. Effect of glycerin and formic acid in the efficiency of deposit on Zn-Ni, obtained by electrodeposition; Efeito da glicerina e do acido formico na eficiencia de deposito da liga Zn-Ni, obtido atraves de eletrodeposicao

    Energy Technology Data Exchange (ETDEWEB)

    Pedroza, G.A.G.; Souza, C.A.C.; Lima, L.R.P.A.; Ferreira, D.M. [Universidade Federal da Bahia - Escola Politecnica, BA (Brazil)

    2010-07-01

    Additives are added to the electrodeposition of metal coatings to improve the characteristics of the deposit. However, the objective was to investigate the effect of adding glycerin and formic acid in the deposition efficiency and deposit structure of zinc-nickel alloy obtained by electrodeposition. The depositions were made at a galvanostatic current density of 10 mA/cm{sup 2} to obtain a deposit of about 5 mm in thickness. The deposition efficiency was determined through measures of mass, chemical composition of the deposit in the presence and absence of additives was examined by X-ray Spectrometer Fluorescence (XRF) and surface characterization of coatings was performed by Scanning Electron Microscopy (SEM). The high levels of glycerin (0,07 M) and formic acid (0,26 M) in bath deposition increased the deposition efficiency of around 10% to 12% by mass, respectively. (author)

  16. Electrolytic deposition of calcium phosphate/chitosan coating on titanium alloy: Growth kinetics and influence of current density, acetic acid, and chitosan

    NARCIS (Netherlands)

    Wang, Jiawei; Apeldoorn, van Aart; Groot, de Klaas

    2006-01-01

    Electrolytically deposited calcium phosphate/chitosan coating demonstrated good bone marrow stromal cell attachment. The aim of this study was to understand the coating's growth kinetics as well as the effects of current density, acetic acid, and chitosan on the coating's formation. The scanning ele

  17. Changes in species richness and composition in European acidic grasslands over the past 70 years: the contribution of cumulative atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dupre, C.; Ranke, T.; Diekmann, M. [Institute of Ecology, FB 2, University of Bremen, Leobener Str., DE-28359 Bremen (Germany); Stevens, C.J.; Dise, N.B. [Department of Environmental and Geographical Science, Manchester Metropolitan University, Manchester M15 GD (United Kingdom); Bleeker, A. [Department of Air Quality and Climate Change, Energy research Centre of the Netherlands, PO Box 1, 1755 ZG Petten (Netherlands); Peppler-Lisbach, C. [Department of Biology and Environmental Sciences, University of Oldenburg, PO Box 2503, DE-26111 Oldenburg (Germany); Gowing, D.J.G. [The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Dorland, E. [Utrecht University, Institute of Environmental Biology, Section of Landscape Ecology, PO Box 80084, 3508 TB Utrecht (Netherlands); Bobbink, R. [B-WARE Research Centre, Radboud University, PO Box 9010, 6525 ED Nijmegen (Netherlands)

    2010-01-15

    Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a temporal comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.

  18. Wet deposition in the northeastern United States

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, J; Mohnen, V; Kadlecek, J

    1980-12-01

    Attempts are made to examine concentration and wet deposition of pollutant material at selected stations within the northeastern United States and to characterize as many events as possible with respect to air mass origin. Further attempts are made to develop a regional pattern for the deposition of dominant ion species. MAP3S (US Multistate Atmospheric Power Production Pollution Study) data for 1977 to 1979 are used to determine concentration and deposition on an event basis from which monthly, seasonal, annual, and cumulative averages are developed. The ARL-ATAD trajectory model is used to characterize individual events as to air mass origin. Case studies are examined to illustrate variability in the chemical composition of precipitation originating from distinctly different air mass trajectories. A difference in concentration of pollution-related ions in precipitation is noted between Midwest/Ohio Valley and Great Lakes/Canadian air mass origins for carefully selected cases. Total deposition of the major ions is examined in an effort to develop a regional pattern for deposition over a period of at least one year. For that purpose, total deposition is normalized to remove the variability in precipitation amounts for inter-station comparison. No marked gradient is noted in the normalized deposition totals within the northeast of the United States. The Adirondack region exhibited the lowest normalized ion deposition value, while the Illinois station showed the highest of the MAP3S network. The data analysis suggest that the acid rain phenomena covers the entire northeast. The concept of large scale mixing emerges to account for the lack of a significant gradient in the normalized deposition.

  19. Lipoprotein lipase expression, serum lipid and tissue lipid deposition in orally-administered glycyrrhizic acid-treated rats

    Directory of Open Access Journals (Sweden)

    Ton So

    2009-07-01

    Full Text Available Abstract Background The metabolic syndrome (MetS is a cluster of metabolic abnormalities comprising visceral obesity, dyslipidaemia and insulin resistance (IR. With the onset of IR, the expression of lipoprotein lipase (LPL, a key regulator of lipoprotein metabolism, is reduced. Increased activation of glucocorticoid receptors results in MetS symptoms and is thus speculated to have a role in the pathophysiology of the MetS. Glycyrrhizic acid (GA, the bioactive constituent of licorice roots (Glycyrrhiza glabra inhibits 11β-hydroxysteroid dehydrogenase type 1 that catalyzes the activation of glucocorticoids. Thus, oral administration of GA is postulated to ameliorate the MetS. Results In this study, daily oral administration of 50 mg/kg of GA for one week led to significant increase in LPL expression in the quadriceps femoris (p p > 0.05 of the GA-treated rats compared to the control. Decrease in adipocyte size (p > 0.05 in both the visceral and subcutaneous adipose tissue depots accompanies such selective induction of LPL expression. Consistent improvement in serum lipid parameters was also observed, with decrease in serum free fatty acid, triacylglycerol, total cholesterol and LDL-cholesterol but elevated HDL-cholesterol (p > 0.05. Histological analysis using tissue lipid staining with Oil Red O showed significant decrease in lipid deposition in the abdominal muscle and quadriceps femoris (p p > 0.05. Conclusion Results from this study may imply that GA could counteract the development of visceral obesity and improve dyslipidaemia via selective induction of tissue LPL expression and a positive shift in serum lipid parameters respectively, and retard the development of IR associated with tissue steatosis.

  20. Partitioning and granulometric distribution of metal leachate from urban traffic dry deposition particulate matter subject to acidic rainfall and runoff retention.

    Science.gov (United States)

    Sansalone, J; Ying, G

    2008-09-01

    Vehicular transportation coupled with urban hydrology is a significant source as well as vector of particulate matter (PM) and particulate-bound metal inventories in urban systems. This study examines the granulometric distribution of metals from dry deposition PM generated from 17 dryfall periods and equilibrium metal partitioning with runoff PM distribution from eight rainfall-runoff events at an urban inter-state watershed in Baton Rouge, LA. Dry deposition PM is a coarse non-uniform gradation with a d(50 m)=304 microm and a peak surface area at 106 microm. Results indicate acid rain is not a significant metal contributor to runoff but is capable of leaching metals from PM to runoff. Retained runoff partitioning resulted in particulate-bound predominance for As, Cd, Cr, Cu, Pb, and Zn while Ca and Mg remained predominately dissolved. The finer PM fraction (75 microm). This coarse fraction is also the most labile when exposed to acidic rainfall; generating up to 90% of the total metal mass leached from the entire PM gradation. Comparing dry deposition and runoff PM of equal mass and size gradation, retained runoff PM is enriched with metals (except Pb). Results indicate the labile coarse fraction of dry deposition PM can be a significant source of metal leaching while runoff PM (mobilized dry deposition PM) stored in a BMP can be metal-enriched with the potential for re-leaching or scour.

  1. Compositional gradients in Gramineae genes

    DEFF Research Database (Denmark)

    Wong, Gane Ka-Shu; Wang, Jun; Tao, Lin;

    2002-01-01

    In this study, we describe a property of Gramineae genes, and perhaps all monocot genes, that is not observed in eudicot genes. Along the direction of transcription, beginning at the junction of the 5'-UTR and the coding region, there are gradients in GC content, codon usage, and amino-acid usage...

  2. Deterioration of concrete structures by acid deposition — an assessment of the role of rainwater on deterioration by laboratory and field exposure experiments using mortar specimens

    Science.gov (United States)

    Okochi, Hiroshi; Kameda, Hideki; Hasegawa, Shin-ichi; Saito, Nobuhiko; Kubota, Ken; Igawa, Manabu

    Deterioration of concrete structures caused by acid deposition was investigated by laboratory and field exposure of portland cement mortar specimens to acid deposition. Laboratory exposure experiment showed that the dissolved amount of calcium hydrates, which were the major components in mortar, increased with the increase in the acidity of simulated acid rain solution and the decrease in the flow rate. There was little difference in their amount among different temperature treatments after each exposure to the solution with the same acidity, namely left at room temperature, heated at 70°C, and cooled at -2°C. The neutralization progressed more deeply under the heated and cooled condition and was accelerated by even acid rain with pH 4.7 during a long period (90 exposure cycles, which correspond to the rainfall amount of 15 years in Japan). A field exposure experiment for two years indicated that the carbonation of calcium hydrates and the formation of other corrosion products such as chloride, nitrate, and sulfate were limited to the surface of mortar specimens. The neutralization progressed more deeply in mortar specimens sheltered from rainwater than in those washed by rainwater.

  3. The Effects of Gaseous Ozone and Nitric Acid Deposition on two Crustose Lichen Species From Joshua Tree National Park

    Science.gov (United States)

    Hessom, Elizabeth Curie

    Lichens are dependent on atmospheric deposition for much of their water and nutrients, and due to their sensitivity to pollutants, are commonly used as bioindicators for air quality. While studies have focused on epiphytic (tree dwelling) lichens as bioindicators, virtually nothing is known about crustose (rock dwelling) lichens. The atmospheric pollutants ozone (O 3) and nitric acid (HNO3) are two major pollutants found within the Los Angeles Basin. While recent O3 research suggests it does not significantly affect lichen growth, HNO3 appears to be phytotoxic to some lichens. As both of these pollutants are deposited downwind from the L.A. basin into Joshua Tree National Park (JOTR), lichen species located in the park may provide a sensitive indicator of pollution effects. This research studied two lichen species of particular interest from Joshua Tree National Park, Lobothallia praeradiosa (Nyl.) Hafellner, and Acarospora socialis H. Magn., both of which are crustose species with unknown sensitivities to O3, as well as hypothesized and unknown sensitivities to nitrogen compounds, respectively. Little research exists for either species, possibly because of the difficulty in working with crustose lichens. This research attempted to expand the background knowledge of these species by exposing them to varying levels of O3 and HNO3, to ascertain their physiological responses. Physiological measures of chlorophyll fluorescence, dark respiration, microscopic imaging, and lichen washes (as a proxy for membrane leakage), were measured throughout the exposure period. Results indicated that both species had similar sensitivities to O3 and HNO3. Both species registered physical damage during the O3 fumigation, as well as a decrease in respiration. Neither species showed major physical damage to HNO3, but both manifested a decrease in chlorophyll fluorescence, suggesting damage to the photosynthetic systems of the algae symbiont. These results suggest that both of these

  4. GIS analysis of vulnerability to acidic deposition of soils in a region of the Northern Appennines; Uso di tecniche GIS per lo studio della sensibilita` alle deposizioni acide dei suoli di una area dell`Appennino piacentino e parmense

    Energy Technology Data Exchange (ETDEWEB)

    Vincini, Massimo [Piacenza, Univ. Cattolica del Sacro Cuore (Italy). Lab. Centralizzato Radioisotopi; Solinas, Chiara [Piacenza, Univ. Cattolica del Sacro Cuore (Italy). Fac. di Agraria. Istituto di Entomologia e Patologia Vegetale

    1997-04-01

    A study on the vulnerability to acidic depositions of the soils of forested ecosystems is conducted by GIS analysis in a region of the Northern Appennines. On the basis of soil pH and yearly precipitation the yearly soil intake of H{sup +} from unpolluted rain (pH 5.6) is calculated by Henderson-Hasselbach equation. The area of possible vulnerability to strong acidic anions such as SO{sub 4}{sup 2-} (soil pH {<=} 5.8 and lime content {<=} 0.5 %) is related to yearly precipitation in order to show the extension and the localization of forested ecosystems whose soils are more likely affected by base leaching as a long-term consequence of acidic depositions.

  5. Effective anisotropy gradient in pressure graded [Co/Pd] multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, B. J., E-mail: bkirby@nist.gov; Maranville, B. B. [Center for Neutron Research, NIST, Gaithersburg, Maryland 20899 (United States); Greene, P. K.; Liu, Kai [Physics Department, University of California, Davis, California 95616 (United States); Davies, J. E. [Advanced Technology Group, NVE Corporation, Eden Prarie, Minneapolis 55344 (United States)

    2015-02-14

    We have used polarized neutron reflectometry to show that controlled variation of growth pressure during deposition of Co/Pd multilayers can be used to achieve a significant vertical gradient in the effective anisotropy. This gradient is strongly dependent on deposition order (low to high pressure or vice versa), and is accompanied by a corresponding gradient in saturation magnetization. These results demonstrate pressure-grading as an attractively simple technique for tailoring the anisotropy profile of magnetic media.

  6. Evidence for Siliceous Deposits Formed by Acid-Sulfate Alteration at Home Plate in Gusev Crater, Mars

    Science.gov (United States)

    Morris, R. V.; Ming, D. W.; Gellert, R.; Yen, A. S.; Clark, B. C.; Ruff, S. W.; Graff, T. G.; Arvidson, R. E.; Squyres, S. W.; Science Teams, T.

    2007-12-01

    at 9 and 21 microns are emissivity minima and, like Gertrude Weise, the feature near 8 microns is also an emissivity minimum. The <150 micron powder has additional spectral features in the transparency region between about 9.5 and 12 microns. The correspondence of available chemical and thermal emission data for the terrestrial analog and martian samples implicates a common formation pathway, i.e., acid sulfate alteration in a fumarolic environment. Although other formation pathways merit investigation for the martian samples (e.g., SiO2 sinters), acid-sulfate conditions in a fumarolic environment are consistent with the proposed volcanic origin for Home Plate and with the presence of SO3-rich (22 to 35 %) soils and clods in the vicinity of Home Plate. These ferric sulfate rich materials also show excess SiO2 by mass balance. By analogy with VNIR spectra for the Kilauea sample, a broad M-OH spectral feature at 2.25 microns detected from martian orbit by CRISM or OMEGA can be interpreted as evidence for high-SiO2 deposits on the surface.

  7. THE EFFECT OF Sauropus androgynus EXTRACT AND LEMURU OIL ON FAT DEPOSITION AND FATTY ACID COMPOSITION OF MEAT IN BROILER CHICKENS

    Directory of Open Access Journals (Sweden)

    U. Santoso

    2014-10-01

    Full Text Available The present study was conducted to evaluate the effect of Sauropus androgynus (katuk leavesextract (SAE and lemuru fish oil (LO on fat deposition and fatty acid composition of meat in broilerchickens. One hundred and fifty six broiler chickens were distributed to 13 treatment groups with 3cages in each treatment group as replicate. Completely randomized design was used in this study. Thethirteen groups were subsequent of broiler chickens that were fed diet containing commercial feedsupplement as a control (P1, 10 g/kg SAE and 1% LO (P2; 10 g/kg SAE and 1% LO plus 60 mgvitamin E (P3, 10 g/kg SAE and 2% LO (P4, 10 g/kg SAE and 2% LO plus 60 mg vitamin E (P5, 10g/kg SAE and 3% LO (P6, 10 g/kg SAE and 3% LO plus 60 mg vitamin E (P7, 18 g/kg SAE and 1%LO (P8, 18 g/kg SAE and 1% LO plus 60 mg vitamin E (P9, 18 g/kg SAE and 2% LO (P10, were18 g/kg SAE and 2% LO plus 60 mg vitamin E (P11, 18 g/kg SAE and 3% LO (P12, and 18 g/kg SAEand 3% LO plus 60 mg vitamin E (P13. The data were analyzed by analysis of variance and if it weresignificant, it were then determined by Duncan's Multiple Range test. The present results showed thatsupplementation of SAE and LO significantly affected (P<0.05 fat deposition in abdomen and leg, butit had no effect on neck fat deposition and Fatty Liver Score. Supplementation of SAE and LO hadsignificantly reduced (P<0.05 cholesterol content and thiobarbituric acid (TBA in leg meat, but itsignificantly increased (P<0.05 vitamin A and vitamin E and it had no effect on fat in leg meat.Supplementation of SAE and LO proved to change fatty acid composition in leg meat. The treatmenthighly significant increased ecosapentaenoic acid (EPA and docosahexaenoic acid DHA (P<0.01,arachidonic acid and stearic acid (P<0.05, but it significantly reduced linolenic acid (P<0.05. Inconclusion, the supplementation of SAE and LO reduced fat deposition in abdomen and leg, the contentof cholesterol in meat, and it enriched EPA and DHA of meat.

  8. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20110947 Chen Xinglong(Guizhou Bureau of Nonferrous Metal and Nuclear Geology,Guiyang 550005,China);Gong Heqiang Endowment Factors and Development & Utilization Strategy of Bauxite Resource in North Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(2),2010,p.106-110,6 refs.,with English abstract)Key words:bauxite deposit,Guizhou Province20110948 Dang Yanxia(Mineral Resource & Reservoir Evaluation Center,Urumiq 830000,China);Fan Wenjun Geological Features and a Primary Study of Metallogenesis of the Wucaiwang Zeolite Deposit,Fuyun County(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,28(2),2010,p.167-170,2 illus.,1 table,5 refs.)Key words:zeolite deposit,Xinjiang Nearly all zeolite deposits in the world result from low-temperature-alteration of glass-bearing volcanic rocks.The southern slope of the Kalamali Mountain is one of the regions where medium to acid volcanics are major lithological type,thus it is a preferred area to look for zeolite deposit.The Wucaiwang zeolite ore district consists of mainly acid volcanic-clastic rocks.

  9. The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

    OpenAIRE

    Watmough, S. A.; Dillon, P. J.

    2002-01-01

    International audience The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not chang...

  10. The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

    Directory of Open Access Journals (Sweden)

    S. A. Watmough

    2002-01-01

    Full Text Available The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario. In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 μeq l-1. These calculations assume that extremely low calcium leaching losses (9–27 μeq l-1 from

  11. Changes in faunal and vegetation communities along a soil calcium gradient in northern hardwood forests

    Science.gov (United States)

    Beier, Colin M.; Woods, Anne M.; Hotopp, Kenneth P.; Gibbs, James P.; Mitchell, Myron J.; Dovciak, Martin; Leopold, Donald J.; Lawrence, Gregory B.; Page, Blair D.

    2012-01-01

    Depletion of Ca from forest soils due to acidic deposition has had potentially pervasive effects on forest communities, but these impacts remain largely unknown. Because snails, salamanders, and plants play essential roles in the Ca cycle of northern hardwood forests, we hypothesized that their community diversity, abundance, and structure would vary with differences in biotic Ca availability. To test this hypothesis, we sampled 12 upland hardwood forests representing a soil Ca gradient in the Adirondack Mountains, New York (USA), where chronic deposition has resulted in acidified soils but where areas of well-buffered soils remain Ca rich due to parent materials. Along the gradient of increasing soil [Ca2+], we observed increasing trends in snail community richness and abundance, live biomass of redback salamanders (Plethodon cinereus (Green, 1818)), and canopy tree basal area. Salamander communities were dominated by mountain dusky salamanders (Desmognathus ochrophaeus Cope, 1859) at Ca-poor sites and changed continuously along the Ca gradient to become dominated by redback salamanders at the Ca-rich sites. Several known calciphilic species of snails and plants were found only at the highest-Ca sites. Our results indicated that Ca availability, which is shaped by geology and acidic deposition inputs, influences northern hardwood forest ecosystems at multiple trophic levels, although the underlying mechanisms require further study.

  12. Formation of vertical concentration gradients in poly(3-hexylthiophene-2,5-diyl): Phenyl-C61-butyric acid methyl ester-graded bilayer solar cells

    International Nuclear Information System (INIS)

    In the present work, we demonstrate that graded bilayer solar cells provide a very interesting alternative to the bulk heterojunction active layers commonly used in organic photovoltaic cells. One of the main advantages of this type of active layers is the possibility to optimize independently both donor and acceptor layers. Using various process methods, we obtain active layers that demonstrate a donor–acceptor vertical concentration gradient. These devices exhibit not only a high fill factor but also a remarkable increase in open-circuit voltage (Voc). In order to understand the influence of the film morphology over the device parameters, we provide a complete study using energy-dispersive x-ray spectroscopy elemental mapping of the device cross sections, showing evidence that ideal donor–acceptor concentration gradient are required to obtain high fill factors. Furthermore, we use a simple equivalent electrical model to extrapolate device parameters such as reverse saturation current for a clearer understanding of the origin of the Voc increase. - Highlights: • Various donor–acceptor concentration-graded devices were fabricated. • Improved donor–acceptor concentration gradient enhances the photovoltaic properties. • The increased open-circuit voltage results from lower reverse saturation currents. • Adjusting the dimensions of buffer and intermixed layers enhances fill factor. • Ideal active layer morphologies lead to an increase of 30% of the efficiency

  13. Formation of vertical concentration gradients in poly(3-hexylthiophene-2,5-diyl): Phenyl-C{sub 61}-butyric acid methyl ester-graded bilayer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Vohra, Varun, E-mail: varunvohra1984@gmail.com [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Higashimine, Koichi [Nano-material Technology Center, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Tsuzaki, Shogo [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Ohdaira, Keisuke [Green Devices Research Center, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Murata, Hideyuki, E-mail: murata-h@jaist.ac.jp [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2014-03-03

    In the present work, we demonstrate that graded bilayer solar cells provide a very interesting alternative to the bulk heterojunction active layers commonly used in organic photovoltaic cells. One of the main advantages of this type of active layers is the possibility to optimize independently both donor and acceptor layers. Using various process methods, we obtain active layers that demonstrate a donor–acceptor vertical concentration gradient. These devices exhibit not only a high fill factor but also a remarkable increase in open-circuit voltage (V{sub oc}). In order to understand the influence of the film morphology over the device parameters, we provide a complete study using energy-dispersive x-ray spectroscopy elemental mapping of the device cross sections, showing evidence that ideal donor–acceptor concentration gradient are required to obtain high fill factors. Furthermore, we use a simple equivalent electrical model to extrapolate device parameters such as reverse saturation current for a clearer understanding of the origin of the V{sub oc} increase. - Highlights: • Various donor–acceptor concentration-graded devices were fabricated. • Improved donor–acceptor concentration gradient enhances the photovoltaic properties. • The increased open-circuit voltage results from lower reverse saturation currents. • Adjusting the dimensions of buffer and intermixed layers enhances fill factor. • Ideal active layer morphologies lead to an increase of 30% of the efficiency.

  14. Transcriptomic Analysis Identifies Candidate Genes Related to Intramuscular Fat Deposition and Fatty Acid Composition in the Breast Muscle of Squabs (Columba).

    Science.gov (United States)

    Ye, Manhong; Zhou, Bin; Wei, Shanshan; Ding, MengMeng; Lu, Xinghui; Shi, Xuehao; Ding, Jiatong; Yang, Shengmei; Wei, Wanhong

    2016-01-01

    Despite the fact that squab is consumed throughout the world because of its high nutritional value and appreciated sensory attributes, aspects related to its characterization, and in particular genetic issues, have rarely been studied. In this study, meat traits in terms of pH, water-holding capacity, intramuscular fat content, and fatty acid profile of the breast muscle of squabs from two meat pigeon breeds were determined. Breed-specific differences were detected in fat-related traits of intramuscular fat content and fatty acid composition. RNA-Sequencing was applied to compare the transcriptomes of muscle and liver tissues between squabs of two breeds to identify candidate genes associated with the differences in the capacity of fat deposition. A total of 27 differentially expressed genes assigned to pathways of lipid metabolism were identified, of which, six genes belonged to the peroxisome proliferator-activated receptor signaling pathway along with four other genes. Our results confirmed in part previous reports in livestock and provided also a number of genes which had not been related to fat deposition so far. These genes can serve as a basis for further investigations to screen markers closely associated with intramuscular fat content and fatty acid composition in squabs. The data from this study were deposited in the National Center for Biotechnology Information (NCBI)'s Sequence Read Archive under the accession numbers SRX1680021 and SRX1680022. This is the first transcriptome analysis of the muscle and liver tissue in Columba using next generation sequencing technology. Data provided here are of potential value to dissect functional genes influencing fat deposition in squabs.

  15. Transcriptomic Analysis Identifies Candidate Genes Related to Intramuscular Fat Deposition and Fatty Acid Composition in the Breast Muscle of Squabs (Columba).

    Science.gov (United States)

    Ye, Manhong; Zhou, Bin; Wei, Shanshan; Ding, MengMeng; Lu, Xinghui; Shi, Xuehao; Ding, Jiatong; Yang, Shengmei; Wei, Wanhong

    2016-01-01

    Despite the fact that squab is consumed throughout the world because of its high nutritional value and appreciated sensory attributes, aspects related to its characterization, and in particular genetic issues, have rarely been studied. In this study, meat traits in terms of pH, water-holding capacity, intramuscular fat content, and fatty acid profile of the breast muscle of squabs from two meat pigeon breeds were determined. Breed-specific differences were detected in fat-related traits of intramuscular fat content and fatty acid composition. RNA-Sequencing was applied to compare the transcriptomes of muscle and liver tissues between squabs of two breeds to identify candidate genes associated with the differences in the capacity of fat deposition. A total of 27 differentially expressed genes assigned to pathways of lipid metabolism were identified, of which, six genes belonged to the peroxisome proliferator-activated receptor signaling pathway along with four other genes. Our results confirmed in part previous reports in livestock and provided also a number of genes which had not been related to fat deposition so far. These genes can serve as a basis for further investigations to screen markers closely associated with intramuscular fat content and fatty acid composition in squabs. The data from this study were deposited in the National Center for Biotechnology Information (NCBI)'s Sequence Read Archive under the accession numbers SRX1680021 and SRX1680022. This is the first transcriptome analysis of the muscle and liver tissue in Columba using next generation sequencing technology. Data provided here are of potential value to dissect functional genes influencing fat deposition in squabs. PMID:27175015

  16. Transcriptomic Analysis Identifies Candidate Genes Related to Intramuscular Fat Deposition and Fatty Acid Composition in the Breast Muscle of Squabs (Columba

    Directory of Open Access Journals (Sweden)

    Manhong Ye

    2016-07-01

    Full Text Available Despite the fact that squab is consumed throughout the world because of its high nutritional value and appreciated sensory attributes, aspects related to its characterization, and in particular genetic issues, have rarely been studied. In this study, meat traits in terms of pH, water-holding capacity, intramuscular fat content, and fatty acid profile of the breast muscle of squabs from two meat pigeon breeds were determined. Breed-specific differences were detected in fat-related traits of intramuscular fat content and fatty acid composition. RNA-Sequencing was applied to compare the transcriptomes of muscle and liver tissues between squabs of two breeds to identify candidate genes associated with the differences in the capacity of fat deposition. A total of 27 differentially expressed genes assigned to pathways of lipid metabolism were identified, of which, six genes belonged to the peroxisome proliferator-activated receptor signaling pathway along with four other genes. Our results confirmed in part previous reports in livestock and provided also a number of genes which had not been related to fat deposition so far. These genes can serve as a basis for further investigations to screen markers closely associated with intramuscular fat content and fatty acid composition in squabs. The data from this study were deposited in the National Center for Biotechnology Information (NCBI’s Sequence Read Archive under the accession numbers SRX1680021 and SRX1680022. This is the first transcriptome analysis of the muscle and liver tissue in Columba using next generation sequencing technology. Data provided here are of potential value to dissect functional genes influencing fat deposition in squabs.

  17. Correlation of acidic and basic carrier ampholyte and immobilized pH gradient two-dimensional gel electrophoresis patterns based on mass spectrometric protein identification

    DEFF Research Database (Denmark)

    Nawrocki, A; Larsen, Martin Røssel; Podtelejnikov, A V;

    1998-01-01

    -MS) to determine the identities of 335 protein spots in these two 2-D gel systems, including a substantial number of basic proteins which had never been identified before. Proteins that were identified in both gel systems allowed us to cross-reference the gel patterns. Vector analysis of these cross......-references demonstrated that there is no obvious pattern by which the mobility of a protein in one gel system can be used to predict its mobility in the other. Thus, as laboratories adopt the immobilized pH gradient-based 2-D gel systems, the only reliable means of translating the data gained with the carrier ampholyte...

  18. Changes in stream chemistry and biology in response to reduced levels of acid deposition during 1987-2003 in the Neversink River Basin, Catskill Mountains

    Science.gov (United States)

    Burns, Douglas A.; Riva-Murray, K.; Bode, R.W.; Passy, S.

    2008-01-01

    Atmospheric acid deposition has decreased in the northeastern United States since the 1970s, resulting in modest increases in pH, acid-neutralizing capacity (ANC), and decreases in inorganic monomeric aluminum (AlIM) concentrations since stream chemistry monitoring began in the 1980s in the acid-sensitive upper Neversink River basin in the Catskill Mountains of New York. Stream pH has increased by 0.01 units/year during 1987-2003 at three sites in the Neversink basin as determined by Seasonal Kendall trend analysis. In light of this observed decrease in stream acidity, we sampled 12 stream sites within the Neversink River watershed for water chemistry, macroinvertebrates, fish, and periphytic diatoms in 2003 to compare with a similar data set collected in 1987. Metrics and indices that reflect sensitivity to stream acidity were developed with these biological data to determine whether changes in stream biota over the intervening 16 years parallel those of stream chemistry. Statistical comparisons of data on stream chemistry and an acid biological assessment profile (Acid BAP) derived from invertebrate data showed no significant differences between the two years. For pH and ANC, however, values in 2003 were generally lower than those in 1987; this difference likely resulted from higher streamflow in summer 2003. Despite these likely flow-induced changes in summer 2003, an ordination and cluster analysis of macroinvertebrate taxa based on the Acid BAP indicated that the most acidic sites in the upstream half of the East Branch Neversink River form a statistically significant separate cluster consistent with less acidic stream conditions. This analysis is consistent with limited recovery of invertebrate species in the most acidic reaches of the river, but will require additional improvement in stream chemistry before a stronger conclusion can be drawn. Data on the fish and periphytic diatom communities in 2003 indicate that slimy sculpin had not extended their habitat

  19. Photosynthesis and oxidative stress in the restinga plant species Eugenia uniflora L. exposed to simulated acid rain and iron ore dust deposition: potential use in environmental risk assessment.

    Science.gov (United States)

    Neves, Natália Rust; Oliva, Marco Antonio; da Cruz Centeno, Danilo; Costa, Alan Carlos; Ribas, Rogério Ferreira; Pereira, Eduardo Gusmão

    2009-06-01

    The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPM(Fe)) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPM(Fe) application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers.

  20. Expression of genes controlling unsaturated fatty acids biosynthesis and oil deposition in developing seeds of Sacha inchi (Plukenetia volubilis L.).

    Science.gov (United States)

    Wang, Xiaojuan; Liu, Aizhong

    2014-10-01

    Sacha inchi (Plukenetia volubilis L., Euphorbiaceae) seed oil is rich in α-linolenic acid, a kind of n-3 fatty acids with many health benefits. To discover the mechanism underlying α-linolenic acid accumulation in sacha inchi seeds, preliminary research on sacha inchi seed development was carried out from one week after fertilization until maturity, focusing on phenology, oil content, and lipid profiles. The results suggested that the development of sacha inchi seeds from pollination to mature seed could be divided into three periods. In addition, investigations on the effect of temperature on sacha inchi seeds showed that total oil content decreased in the cool season, while unsaturated fatty acid and linolenic acid concentrations increased. In parallel, expression profiles of 17 unsaturated fatty acid related genes were characterized during seed development and the relationships between gene expression and lipid/unsaturated fatty acid accumulation were discussed. PMID:25119487

  1. Study of the adhesive properties versus stability/aging of hernia repair meshes after deposition of RF activated plasma polymerized acrylic acid coating.

    Science.gov (United States)

    Rivolo, Paola; Nisticò, Roberto; Barone, Fabrizio; Faga, Maria Giulia; Duraccio, Donatella; Martorana, Selanna; Ricciardi, Serena; Magnacca, Giuliana

    2016-08-01

    In order to confer adhesive properties to commercial polypropylene (PP) meshes, a surface plasma-induced deposition of poly-(acrylic acid) (PPAA) is performed. Once biomaterials were functionalized, different post-deposition treatments (i.e. water washing and/or thermal treatments) were investigated with the aim of monitoring the coating degradation (and therefore the loss of adhesion) after 3months of aging in both humid/oxidant (air) and inert (nitrogen) atmospheres. A wide physicochemical characterization was carried out in order to evaluate the functionalization effectiveness and the adhesive coating homogeneity by means of static water drop shape analysis and several spectroscopies (namely, FTIR, UV-Visible and X-ray Photoemission Spectroscopy). The modification of the adhesion properties after post-deposition treatments as well as aging under different storage atmospheres were investigated by means of Atomic Force Microscopy (AFM) used in Force/Distance (F/D) mode. This technique confirms itself as a powerful tool for unveiling the surface adhesion capacity as well as the homogeneity of the functional coatings along the fibers. Results obtained evidenced that post-deposition treatments are mandatory in order to remove all oligomers produced during the plasma-treatment, whereas aging tests evidenced that these devices can be simply stored in presence of air for at least three months without a meaningful degradation of the original properties. PMID:27157754

  2. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C. PMID:27295338

  3. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  4. Continuous gradient temperature Raman spectroscopy of the long chain polyunsaturated fatty acids docosapentaenoic (DPA, 22:5n-6) and docosahexaenoic (DHA; 22:6n-3) from -100 to 20° C

    Science.gov (United States)

    Broadhurst, C. Leigh; Schmidt, Walter F.; Kim, Moon S.; Nguyen, Julie K.; Qin, Jianwei; Chao, Kuanglin; Bauchan, Gary L.; Shelton, Daniel R.

    2016-05-01

    The structural, cognitive and visual development of the human brain and retina strictly require long-chain polyunsaturated fatty acids (LC-PUFA). Excluding water, the mammalian brain is about 60% lipid. One of the great unanswered questions with respect to biological science in general is the absolute necessity of the LC-PUFA docosahexaenoic acid (DHA; 22:6n-3) in these fast signal processing tissues. A lipid of the same chain length with just one less diene group, docosapentaenoic acid (DPA; 22:5n-6) is fairly abundant in terrestrial food chains yet cannot substitute for DHA. Gradient Temperature Raman spectroscopy (GTRS) applies the temperature gradients utilized in differential scanning calorimetry to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur near and at phase transitions. Herein we apply GTRS to DPA, and DHA from -100 to 20°C. 20 Mb three-dimensional data arrays with 1°C increments and first/second derivatives allows complete assignment of solid, liquid and transition state vibrational modes, including low intensity/frequency vibrations that cannot be readily analyzed with conventional Raman. DPA and DHA show significant spectral changes with premelting (-33 and -60°C, respectively) and melting (-27 and -44°C, respectively). The CH2-(HC=CH)-CH2 moieties are not identical in the second half of the DHA and DPA structures. The DHA molecule contains major CH2 twisting (1265 cm-1) with no noticeable CH2 bending, consistent with a flat helical structure with small pitch. Further modeling of neuronal membrane phospholipids must take into account this structure for DHA, which would be configured parallel to the hydrophilic head group line.

  5. Study of underpotential deposited Cu layers on Pt(111) and their stability against CO and CO2 in perchloric acid

    DEFF Research Database (Denmark)

    Schlaup, Christian Georg; Horch, Sebastian

    2013-01-01

    The underpotential deposition (UPD) of copper on a Pt(111) electrode and the influence of gas coadsorbates, i.e. CO and CO2, on the thus deposited copper layer were studied in a 0.1 M HClO4 electrolyte by means of EC-STM. By UPD, an atomically flat Cu layer is formed, which exhibits a pseudomorphic...... vacancy islands. This phase transition is induced by the preferential binding of CO to the Pt(111) surface. In contrast, CO2, which binds stronger to copper, does not affect the pseudomorphic structure of the Cu layer....

  6. WRF/Chem study of dry and wet deposition of trifluoroacetic acid produced from the atmospheric degradation of a few short-lived HFCs

    Science.gov (United States)

    Kazil, J.; McKeen, S. A.; Kim, S.; Ahmadov, R.; Grell, G. A.; Talukdar, R. K.; Ravishankara, A. R.

    2011-12-01

    HFC-134a (1,1,1,2-tetrafluoroethane) is the prevalent (used in >80% passenger cars and commercial vehicles worldwide) refrigerant in automobile air conditioning units (MACs). With an atmospheric lifetime of ~14 years and a global warming potential (GWP) of 1430 on a 100-year time horizon, HFC-134a does not meet current and expected requirements for MAC refrigerants in many parts of the world. Therefore, substitutes with lower GWP are being sought. One of the simplest way to achieve lower GWP is to use chemicals with shorter atmospheric lifetimes. In this work, we investigate the dry and wet deposition and the rainwater concentration of trifluoroacetic acid (TFA) produced by the atmospheric oxidation of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The WRF/Chem model was used to calculate dry and wet TFA deposition over the contiguous USA during the May-September 2006 period that would result from replacing HFC-134a in MACs with a 1:1 molar ratio mixture of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The simulation is evaluated by comparing observations of precipitation and sulfate wet deposition at stations of the National Atmospheric Deposition Program (NADP). Simulated precipitation and sulfate wet deposition correlate well with the observations, but exhibit a positive bias for precipitation and a negative bias for sulfate wet deposition. Atmospheric lifetimes of TFP and PFP against oxidation by the hydroxyl radical OH, a prognostic species in WRF/Chem, are ~5 and ~4 days in the simulation, respectively. The model setup allows the attribution of dry and wet TFA deposition to individual source regions (California, Houston, Chicago, and the remaining contiguous USA in this work). TFA deposition is highest in the eastern USA because of numerous large sources and high precipitation in the region. West of the Continental Divide, TFA deposition is significantly lower, and its origin is dominated by emissions from

  7. Chemical and mineralogical changes of waste and tailings from the Murgul Cu deposit (Artvin, NE Turkey): implications for occurrence of acid mine drainage.

    Science.gov (United States)

    Sağlam, Emine Selva; Akçay, Miğraç

    2016-04-01

    Being one of the largest copper-producing resources in Turkey, the Murgul deposit has been a source of environmental pollution for very long time. Operated through four open pits with an annual production of about 3 million tons of ore at an average grade of about 0.5 % Cu, the deposit to date has produced an enormous pile of waste (exceeding 100 million tons) with tailings composed of 36 % SiO2, 39 % Fe2O3 and 32 % S, mainly in the form of pyrite and quartz. Waters in the vicinity of the deposit vary from high acid-acid (2.71-3.85) and high-extremely metal rich (34.48-348.12 mg/l in total) in the open pits to near neutral (6.51-7.83) and low metal (14.39-973.52 μg/l in total) in downstream environments. Despite low metal contents and near neutral pH levels of the latter, their suspended particle loads are extremely high and composed mainly of quartz and clay minerals with highly elevated levels of Fe (3.5 to 24.5 % Fe2O3; 11 % on average) and S (0.5 to 20.6 % S; 7 % on average), showing that Fe is mainly in the form of pyrite and lesser hematite. They also contain high concentrations of As, Au, Ba, Cu, Pb, and Zn. Waters collected along the course of polluted drainages are supersaturated with respect to Fe phases such as goethite, hematite, maghemite, magnetite, schwertmannite and ferrihydrite. Secondary phases such as Fe-sulphates are only found near the pits, but not along the streams due to neutral pH conditions, where pebbles are covered and cemented by Fe-oxides and hydroxides indicating that oxidation of pyrite has taken place especially at times of low water load. It follows, then, that the pyrite-rich sediment load of streams fed by the waste of the Murgul deposit is currently a big threat to the aquatic life and environment and will continue to be so even after the closure of the deposit. In fact, the oxidation will be enhanced and acidity increased due to natural conditions, which necessitates strong remedial actions to be taken. PMID:26637995

  8. Advanced zirconia-coated carbonyl-iron particles for acidic magnetorheological finishing of chemical-vapor-deposited ZnS and other IR materials

    Science.gov (United States)

    Salzman, S.; Giannechini, L. J.; Romanofsky, H. J.; Golini, N.; Taylor, B.; Jacobs, S. D.; Lambropoulos, J. C.

    2015-10-01

    We present a modified version of zirconia-coated carbonyl-iron (CI) particles that were invented at the University of Rochester in 2008. The amount of zirconia on the coating is increased to further protect the iron particles from corrosion when introduced to an acidic environment. Five low-pH, magnetorheological (MR) fluids were made with five acids: acetic, hydrochloric, nitric, phosphoric, and hydrofluoric. All fluids were based on the modified zirconia-coated CI particles. Off-line viscosity and pH stability were measured for all acidic MR fluids to determine the ideal fluid composition for acidic MR finishing of chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and other infrared (IR) optical materials, such as hot-isostatic-pressed (HIP) ZnS, CVD zinc selenide (ZnSe), and magnesium fluoride (MgF2). Results show significant reduction in surface artifacts (millimeter-size, pebble-like structures on the finished surface) for several standard-grade CVD ZnS substrates and good surface roughness for the non-CVD MgF2 substrate when MR finished with our advanced acidic MR fluid.

  9. The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

    OpenAIRE

    Watmough, S. A.; Dillon, P. J.

    2002-01-01

    The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best c...

  10. A chemical index of weathering without effect of wind sorting: Fe/Mg ratios in the acid-insoluble phases of loess deposits

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical analysis of acid-insoluble fractions in loess and paleosols shows that concentrations of Fe and Mg were under control of wind sorting and post-depositional weathering-pedogenesis. The former caused Fe and Mg concentrated in the finer grain-size fractions, displaying synchronous variations, while the latter made Fe and Mg separated, leading to Fe retained in the weathered section and Mg leached out. Therefore, Fe/Mg ratios in the acid insoluble fraction of loess and paleosols can eliminate the effect of wind sorting and serve as an excellent proxy record on intensity of weathering-pedogenesis. Based on calculation,leaching percentage of Mg in the paleosol S1 from the Luochuan, Xifeng and Huanxian sections is 15%, 11% and 2%,respectively, and on average 9% for the paleosols S2-S14from the Luochuan section, with the highest value amounting to 22% in Ss-1, suggesting the strongest weathering-pedogenesis.``

  11. Reductive Leaching Kinetics of Low Grade Manganese Deposits in H2SO4 Solution Using Malonic Acid as Reducing Agent

    OpenAIRE

    Taysser Lasheen; S. A. Abu Elenein; Saleh, W A; A. H Orabi; D. A Ismaiel

    2014-01-01

    A leaching process was developed to extract manganese and metal values from Alloga manganese concentrate. The preferential leaching process was achieved through reductive leaching in dilute sulfuric acid medium with malonic acid as the reducing agent. Leaching parameters were optimized as 1.0 M H2SO4, 10% malonic acid in solid/liquid ratio 1:10 for 90 min at 80 C and using ore ground to – 74 µm. Under these conditions, the leaching efficiency of manganese reaches 97%, whilst iron dissolution ...

  12. Application of flow injection gradient titration based on the standard addition and dilution procedure to the determination of total acidity in vinegars and soft drinks.

    Science.gov (United States)

    Wójtowicz, Marzena; Kozak, Joanna; Górnacka, Dorota; Koscielniak, Pawel

    2008-12-01

    The proposed approach relies on successive dilution of a solution containing a sample with standard addition and on titration of the solutions obtained until receiving a signal lower than the signal measured for the sample alone. Equations are derived for subsequent dilution factors for the automatic flow injection system applied. The overall calibration strategy including the possibility of prediction of the number of required standard solutions and of positioning the sample signal within the calibration range is presented. The method has been tested on the spectrophotometric determination of hydrochloric acid at two concentration levels (0.193 and 1.21 mol L(-1)) with sodium hydroxide as titrant. The results of accuracy better than |3.9|% (RE) and repeatability better than 1.3% (RSD) were obtained. The method has been applied to the determination of total acidity in vinegars and soft drinks. The average time necessary to analyze one sample is about 10 min. PMID:19075470

  13. Electronic properties of the surface of perylene tetracarboxylic acid dianhydride film upon deposition of the ultrathin conjugated layers of Pyronine B

    Energy Technology Data Exchange (ETDEWEB)

    Komolov, Alexei S., E-mail: akomolov07@ya.ru [Physics Faculty, St. Petersburg State University, Uljanovskaja ul.1, St. Petersburg 198504 (Russian Federation); Lazneva, Eleonora F.; Akhremtchik, Svetlana N. [Physics Faculty, St. Petersburg State University, Uljanovskaja ul.1, St. Petersburg 198504 (Russian Federation)

    2010-02-01

    Ultrathin conjugated layers of Pyronine B were thermally deposited in UHV on the surface of perylene tetracarboxylic acid dianhydride (PTCDA) film. The structure of unoccupied electron states located 5-20 eV above the Fermi level (E{sub F}) and the surface potential were monitored during the Pyronine B overlayer deposition, using an incident beam of low-energy electrons according to the total current electron spectroscopy (TCS) method. Electronic work function of the PTCDA surface changed from 4.9 {+-} 0.1 eV, during the Pyronine B deposition due to the change of the contents of the surface layer, until it reached a stable value 4.6 {+-} 0.1 eV at the Pyronine B film thickness 8-10 nm. The interface dipole corresponds to electron transfer from the Pyronine B overlayer to the PTCDA surface and the polarization in the Pyronine B overlayer was found confined within approximately 1 nm near the interfaces. The edges of major bands of density of unoccupied electronic states (DOUS) of PTCDA substrate and of the Pyronine B overlayer were unaffected by the process of the interface formation. The major TCS spectral features of the Pyronine B film corresponding to the DOUS band edges were identified and the assignment of the {pi}{sup *}, {sigma}{sup *}(C-C) and {sigma}{sup *}(C=C) character was suggested.

  14. Covalent deposition of zwitterionic polymer and citric acid by click chemistry-enabled layer-by-layer assembly for improving the blood compatibility of polysulfone membrane.

    Science.gov (United States)

    Xiang, Tao; Wang, Rui; Zhao, Wei-Feng; Sun, Shu-Dong; Zhao, Chang-Sheng

    2014-05-13

    Development of blood compatible membranes is critical for biomedical applications. Zwitterionic polymers have been proved to be resistant to nonspecific protein adsorption and platelet adhesion. In this work, two kinds of zwitterionic copolymers bearing alkynyl and azide groups are synthesized by atom transfer radical polymerization (ATRP) and subsequent reactions, namely alkynyl-poly(sulfobetaine methacrylate) (alkynyl-PSBMA) and azide-poly(sulfobetaine methacrylate) (azide-PSBMA). The copolymers are directly used to modify azido-functionalized polysulfone (PSf-N3) membrane via click chemistry-enabled layer-by-layer (LBL) assembly. Alkynyl-citric acid is then clicked onto the membrane when the outermost layer was azide-PSBMA. The chemical compositions, surface morphologies, and hydrophilicity of the zwitterionic polymer and citric acid multilayer modified membranes are characterized. The composite multilayer is resistant to protein adsorption and platelet adhesion and also prolongs clotting times, indicating that the blood compatibility is improved. Moreover, after clicking the small molecule anticoagulant alkynyl-citric acid onto the outermost of the zwitterionic multilayer, the membrane shows further improved anticoagulant property. The deposition of zwitterionic polymer and citric acid via click chemistry-enabled LBL assembly can improve the blood compatibility of the PSf membrane.

  15. Modelling regional response of lakewater chemistry to changes in acidic deposition: the MAGIC model applied to lake surveys in southernmost Norway 1974-1986-1995

    Directory of Open Access Journals (Sweden)

    B. J. Cosby

    1998-01-01

    Full Text Available Two methods for modelling regional responses of lake water quality to changes in acidic deposition in southernmost Norway were examined. Both methods are based upon the MAGIC model but differ in mode of regional application; one uses site-specific while the other uses Monte-Carlo methods for model calibration. The simulations of regional responses from both methods were compared with observed responses based on data from three lake surveys in southernmost Norway conducted in 1974, 1986 and 1995. The regional responses of the two modelling approaches were quite similar and agreed well with the observed regional distributions of lakewater chemistry variables. From 1974 to 1986 the observed data indicated that despite a decline of approximately 10% in sulphate (SO4 deposition, the mean acid neutralizing capacity (ANC of lakes in southernmost Norway declined by approximately 6 μeq l-1. Both modelling approaches simulated no change or a very small decline in mean ANC for that period. From 1986 to 1995 the observed data indicated that, in response to an approximate 40% decline in SO4 deposition, the mean ANC of lakes in southernmost Norway increased by 11-16 μeq l-1. The modelling approaches simulated increases of 9-10 μeq l-1 in mean ANC for the same period. Both simulations and observations indicate that > 65% of lakes in southernmost Norway were acidic in 1974 and 1995. Both simulation methods predict that >65% of the lakes in southernmost Norway will have positive ANC values within 10 years of reductions of SO4 deposition to 20% of 1974 levels. Of the two regionalization methods the site-specific method appears preferable, because whereas the Monte-Carlo method gives results for a region as a whole, the site-specific method also reveals patterns within the region. The maintenance of a one-to-one correspondence between simulated and observed systems means that simulation results can be mapped for a geographically explicit presentation of model

  16. A substrate independent approach for generation of surface gradients

    International Nuclear Information System (INIS)

    Recently, surface gradients have attracted significant interest for various research and technological applications. In this paper, we report a facile and versatile method for generating surface gradients of immobilized nanoparticles, nanotopography and ligands that is independent from the substrate material. The method consists of first depositing a functional polymer layer on a substrate and subsequent time controlled immersion of this functionalized substrate in solution gold nanoparticles (AuNPs), silver nanoparticles (AgNPs) or poly (styrenesulfonate) (PSS). Chemical characterization by X-ray Photoelectron Spectroscopy (XPS) and morphological analysis by Atomic Force Microscopy (AFM) show that the density of nanoparticles and the concentration of PSS across the surface increases in a gradient manner. As expected, time of immersion determines the concentration of surface bound species. We also demonstrate the generation of surface gradients of pure nanotopography. This is achieved by depositing a 5 nm thick plasma polymer layer on top of the number density gradient of nanoparticles to achieve a homogeneous surface chemistry. The surface independent approach for generation of surface gradients presented in this paper may open opportunities for a wider use of surface gradient in research and in various technologies. - Highlights: ► We present a substrate independent approach for generation of surface gradients. ► We demonstrate well-defined density gradients of gold and silver nanoparticles. ► We provide an example of pure surface nanotopography gradients. ► We demonstrate concentration gradients of bound ligands

  17. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

    Science.gov (United States)

    Simkin, Samuel M.; Allen, Edith B.; Bowman, William D.; Clark, Christopher M.; Belnap, Jayne; Brooks, Matthew L.; Cade, Brian S.; Collins, Scott L.; Geiser, Linda H.; Gilliam, Frank S.; Jovan, Sarah E.; Pardo, Linda H.; Schulz, Bethany K.; Stevens, Carly J.; Suding, Katharine N.; Throop, Heather L.; Waller, Donald M.

    2016-01-01

    Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha−1⋅y−1, we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha−1⋅y−1 in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States.

  18. Effects of chicory inulin on serum metabolites of uric acid, lipids, glucose, and abdominal fat deposition in quails induced by purine-rich diets.

    Science.gov (United States)

    Lin, Zhijian; Zhang, Bing; Liu, Xiaoqing; Jin, Rui; Zhu, Wenjing

    2014-11-01

    Inulin, a group of dietary fibers, is reported to improve the metabolic disorders. In the present study, we investigated the effects of chicory inulin on serum metabolites of uric acid (UA), lipids, glucose, and abdominal fat deposition in quail model induced by a purine-rich diet. In this study, 60 male French quails were randomly allocated to five groups: CON (control group), MOD (model group), BEN (benzbromarone-treated group), CHI-H (high-dosage chicory inulin-treated group), and CHI-L (low-dosage chicory inulin-treated group). The serum UA level was significantly increased in the model group from days 7 to 28, as well as triglyceride (TG) and free fatty acid (FFA) increased later in the experimental period. The abdominal fat ratio was increased on day 28. Benzbromarone can decrease UA levels on days 14 and 28. The high and low dosage of chicory inulin also decreased serum UA levels on days 7, 14, and 28. The abdominal fat ratio, activity, and protein of acetyl-CoA carboxylase (ACC) were decreased in chicory inulin-treated groups. The activities of xanthine oxidase (XOD) and fatty acid synthase (FAS) were increased in the model group and decreased in the benzbromarone and chicory inulin groups. This study evaluated a quail model of induced hyperuricemia with other metabolic disorders caused by a high-purine diet. The results indicated that a purine-rich diet might contribute to the development of hyperuricemia, hypertriglyceridemia, and abdominal obesity. Chicory inulin decreased serum UA, TG, and abdominal fat deposition in a quail model of hyperuricemia by altering the ACC protein expression and FAS and XOD activities.

  19. Effects of chicory inulin on serum metabolites of uric acid, lipids, glucose, and abdominal fat deposition in quails induced by purine-rich diets.

    Science.gov (United States)

    Lin, Zhijian; Zhang, Bing; Liu, Xiaoqing; Jin, Rui; Zhu, Wenjing

    2014-11-01

    Inulin, a group of dietary fibers, is reported to improve the metabolic disorders. In the present study, we investigated the effects of chicory inulin on serum metabolites of uric acid (UA), lipids, glucose, and abdominal fat deposition in quail model induced by a purine-rich diet. In this study, 60 male French quails were randomly allocated to five groups: CON (control group), MOD (model group), BEN (benzbromarone-treated group), CHI-H (high-dosage chicory inulin-treated group), and CHI-L (low-dosage chicory inulin-treated group). The serum UA level was significantly increased in the model group from days 7 to 28, as well as triglyceride (TG) and free fatty acid (FFA) increased later in the experimental period. The abdominal fat ratio was increased on day 28. Benzbromarone can decrease UA levels on days 14 and 28. The high and low dosage of chicory inulin also decreased serum UA levels on days 7, 14, and 28. The abdominal fat ratio, activity, and protein of acetyl-CoA carboxylase (ACC) were decreased in chicory inulin-treated groups. The activities of xanthine oxidase (XOD) and fatty acid synthase (FAS) were increased in the model group and decreased in the benzbromarone and chicory inulin groups. This study evaluated a quail model of induced hyperuricemia with other metabolic disorders caused by a high-purine diet. The results indicated that a purine-rich diet might contribute to the development of hyperuricemia, hypertriglyceridemia, and abdominal obesity. Chicory inulin decreased serum UA, TG, and abdominal fat deposition in a quail model of hyperuricemia by altering the ACC protein expression and FAS and XOD activities. PMID:25314375

  20. Modelling effects of acid deposition and climate change on soil and run-off chemistry at Risdalsheia, Norway

    Directory of Open Access Journals (Sweden)

    J. P. Mol-Dijkstra

    2001-01-01

    Full Text Available Elevated carbon dioxide levels, caused by anthropogenic emissions of carbon dioxide to the atmosphere, and higher temperature may lead to increased plant growth and uptake of nitrogen, but increased temperature may lead to increased nitrogen mineralisation causing enhanced nitrogen leaching. The overall result of both counteracting effects is largely unknown. To gain insight into the long-term effects, the geochemical model SMART2 was applied using data from the catchment-scale experiments of the RAIN and CLIMEX projects, conducted on boreal forest ecosystems at Risdalsheia, southern Norway. These unique experiments at the ecosystem scale provide information on the short-term effects and interactions of nitrogen deposition and increased temperature and carbon dioxide on carbon and nitrogen cycling and especially the run-off chemistry. To predict changes in soil processes in response to climate change, the model was extended by including the temperature effect on mineralisation, nitrification, denitrification, aluminium dissolution and mineral weathering. The extended model was tested on the two manipulated catchments at Risdalsheia and long-term effects were evaluated by performing long-time runs. The effects of climate change treatment, which resulted in increased nitrogen fluxes at both catchments, were slightly overestimated by SMART2. The temperature dependency of mineralisation was simulated adequately but the temperature effect on nitrification was slightly overestimated. Monitored changes in base cation concentrations and pH were quite well simulated with SMART2. The long-term simulations indicate that the increase in nitrogen run-off is only a temporary effect; in the long-term, no effect on total nitrogen leaching is predicted. At higher deposition levels the temporary increase in nitrogen leaching lasts longer than at low deposition. Contrary to nitrogen leaching, temperature increase leads to a permanent decrease in aluminium

  1. Nitric Acid Deposition following an Astrophysical Ionizing Radiation Event is below Critical Loads for Terrestrial and Freshwater Ecosystems

    CERN Document Server

    Melott, Ben Neuenswander Adrian

    2014-01-01

    Nitric acid rainout is one of the effects of an astrophysical ionizing radiation event. The predicted values of nitrate rainout from previous work for a typical gamma ray burst (GRB) within our galaxy serve as an extreme example and are shown to be below critical loads of eutrophication and acidification for ecoregions in Europe and the US.

  2. Effect of trans fatty acid intake on abdominal and liver fat deposition and blood lipids

    DEFF Research Database (Denmark)

    Bendsen, Nathalie Tommerup; Chabanova, E.; Thomsen, Henrik S.;

    2011-01-01

    Background:Intake of industrially produced trans fatty acids (TFAs) is, according to observational studies, associated with an increased risk of cardiovascular disease, but the causal mechanisms have not been fully elucidated. Besides inducing dyslipidemia, TFA intake is suspected to promote...

  3. Selective deposition of dietary α-lipoic acid in mitochondrial fraction and its synergistic effect with α-tocoperhol acetate on broiler meat oxidative stability.

    Science.gov (United States)

    Parveen, Rashida; Asghar, Ali; Anjum, Faqir M; Khan, Muhammad I; Arshad, Muhammad Sajid; Yasmeen, Ammara

    2013-01-01

    The use of bioactive antioxidants in feed of broiler to mitigate reactive oxygen species (ROS) in biological systems is one of promising nutritional strategies. The aim of present study was to alleviate ROS production in mitochondrial fraction (MF) of meat by supplemented dietary antioxidant in feed of broiler. For this purpose, mitochondria specific antioxidant: α-lipoic acid (25 mg, 75 mg and 150 mg) with or without combination of α-tocopherol acetate (200 mg) used in normal and palm olein oxidized oil (4%) supplemented feed. One hundred and eighty one day old broiler birds were randomly divided into six treatments and provided the mentioned feed from third week. Feed intake, feed conversion ratio (FCR) remained statistically same in all groups while body weight decreased in supplemented groups accordingly at the end of study. The broiler meat MF antioxidant potential was significantly improved by feeding supplemented feed estimated as 1,1-di phenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, 2,2-azinobis-(3- ethylbenzothiazoline-6-sulphonic acid) (ABTS+) and thiobarbituric acid reactive substances (TBARS). The maximum antioxidant activity was depicted in group fed on 150 mg/kg α-lipoic acid (ALA) and 200 mg/kg α-tocopherol acetate (ATA) (T4) in both breast and leg MF. Moreover, TBARS were higher in leg as compared to breast MF. Although, oxidized oil containing feed reduced the growth, lipid stability and antioxidant potential of MF whilst these traits were improved by receiving feed containing ALA and ATA. ALA and ATA showed higher deposition in T4 group while least in group received oxidized oil containing feed (T5). Positive correlation exists between DPPH free radical scavenging activity and the ABTS + reducing activity. In conclusion, ALA and ATA supplementation in feed had positive effect on antioxidant status of MF that consequently diminished the oxidative stress in polyunsaturated fatty acid enriched meat. PMID:23617815

  4. On-Tissue Derivatization via Electrospray Deposition for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Endogenous Fatty Acids in Rat Brain Tissues.

    Science.gov (United States)

    Wu, Qian; Comi, Troy J; Li, Bin; Rubakhin, Stanislav S; Sweedler, Jonathan V

    2016-06-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is used for the multiplex detection and characterization of diverse analytes over a wide mass range directly from tissues. However, analyte coverage with MALDI MSI is typically limited to the more abundant compounds, which have m/z values that are distinct from MALDI matrix-related ions. On-tissue analyte derivatization addresses these issues by selectively tagging functional groups specific to a class of analytes, while simultaneously changing their molecular masses and improving their desorption and ionization efficiency. We evaluated electrospray deposition of liquid-phase derivatization agents as a means of on-tissue analyte derivatization using 2-picolylamine; we were able to detect a range of endogenous fatty acids with MALDI MSI. When compared with airbrush application, electrospray led to a 3-fold improvement in detection limits and decreased analyte delocalization. Six fatty acids were detected and visualized from rat cerebrum tissue using a MALDI MSI instrument operating in positive mode. MALDI MSI of the hippocampal area allowed targeted fatty acid analysis of the dentate gyrus granule cell layer and the CA1 pyramidal layer with a 20-μm pixel width, without degrading the localization of other lipids during liquid-phase analyte derivatization.

  5. On-Tissue Derivatization via Electrospray Deposition for Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging of Endogenous Fatty Acids in Rat Brain Tissues.

    Science.gov (United States)

    Wu, Qian; Comi, Troy J; Li, Bin; Rubakhin, Stanislav S; Sweedler, Jonathan V

    2016-06-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is used for the multiplex detection and characterization of diverse analytes over a wide mass range directly from tissues. However, analyte coverage with MALDI MSI is typically limited to the more abundant compounds, which have m/z values that are distinct from MALDI matrix-related ions. On-tissue analyte derivatization addresses these issues by selectively tagging functional groups specific to a class of analytes, while simultaneously changing their molecular masses and improving their desorption and ionization efficiency. We evaluated electrospray deposition of liquid-phase derivatization agents as a means of on-tissue analyte derivatization using 2-picolylamine; we were able to detect a range of endogenous fatty acids with MALDI MSI. When compared with airbrush application, electrospray led to a 3-fold improvement in detection limits and decreased analyte delocalization. Six fatty acids were detected and visualized from rat cerebrum tissue using a MALDI MSI instrument operating in positive mode. MALDI MSI of the hippocampal area allowed targeted fatty acid analysis of the dentate gyrus granule cell layer and the CA1 pyramidal layer with a 20-μm pixel width, without degrading the localization of other lipids during liquid-phase analyte derivatization. PMID:27181709

  6. Structure Of Conduits Of The Acidic Volcanism And Related Deposits In The Paraná-Etendeka Magmatic Province, São Marcos Region, South Brazil

    Science.gov (United States)

    Guimarães, L. F.; De Campos, C. P.; Lima, E. F. D.; Janasi, V. A.

    2015-12-01

    Voluminous acidic volcanics from the Paraná-Etendeka Magmatic Province crop out in the southern part of Brazil. The conduits responsible for the feeding of this intermediate/acid volcanism are preserved and well exposed in the São Marcos region (Lima et al. 2012; Geologia USP 12:49-64). Conduits are aligned along a NW-SE trend and have thicknesses up to 1 km. These structures are often characterized by mixing between dacitic and rhyodacitic magmas, with intercalation between two major zones: 1) reddish or grayish vitrophiricdacite/rhyodacite, sub-divided in massive or vesiculated; 2) reddish or grayish vitrophiric fragmented dacite/rhyodacite composed of bubble-rich angular to rounded blocks. Such fragments commonly deform coeval to the flow. A third zone dominated by filaments depicts a chaotic stretching-and-folding process from the mixture of the acid magmas. We used classical field measurements of flow structures and recognized main flow directions in these feeder-dikes. They follow two preferential directions: NW, ranging from N272° to N 355°, and NE, varying from N20° to N85°. These directions are indicative of a transtensive fissural system, which seems to be related to conjugated fractures. Evidence of an important fragmentation process in the conduits point towards the presence of related products in this region, thus rheomorphic deposits such as those observed elsewhere (e.g. Uruguay and Namibia) are expected to occur. Possible vestiges of these deposits could be represented by restricted outcrops of lens-shaped and banded hipohyaline, occasionally bubble-rich, dacites. The presence of continuous pseudotachylitic levels, tightly folded bands with horizontal axial planes together with local deformed bubble-rich pumice-like lens could be indicative of remelting and rheomorphism of previous vulcanoclastic material. Coulees and compound (lobed) dacitic lava flows, reaching up to 5-8 meters length, occur as the uppermost deposits and correspond to the

  7. Interpretation of trends in acidic deposition and surface water chemistry in Scotland during the past three decades

    Science.gov (United States)

    Harriman, R.; Watt, A. W.; Christie, A. E. G.; Collen, P.; Moore, D. W.; McCartney, A. G.; Taylor, E. M.; Watson, J.

    Trends in major ionic components of bulk precipitation were analysed for two sites, Faskally and Loch Ard forest in Scotland, for the period 1972-2000. The pattern of change was not linear. Large reductions in sulphur deposition occurred in the early 1980s and, to a lesser extent, during 1995-2000, with a period of relative stability between 1988-95. pH increased significantly at both sites but nitrate and ammonia only increased significantly at Loch Ard forest. Long-term chemical data from a total of 37 streams and lochs in four selected regions of Scotland were analysed over three time periods (all available data (mostly 1978-2000), 1988-98 and 1995-2000) to match the deposition patterns. For the whole study period a significant decline in non-marine sulphate was found at all sites while the most consistent increases in pH and alkalinity were recorded at all the high elevation loch sites in the Galloway area. Significant reductions in toxic forms of aluminium were also recorded, mostly at sites where pH had increased. Nitrate trends were equivocal except for catchments with clear-felling operations. For these sites, negative trends were found where felling occurred in the 1980s, while positive trends were found at sites with felling in the 1990s. With the exception of one site, dissolved organic carbon concentrations increased significantly with moorland sites showing smaller increases than forested sites. Associated with this change was a significant increase in complexed forms of aluminium. Trends for the 1988-98 period were much smaller than those for the whole study period and in many cases were insignificant. This contrasts with the 1995-2000 period when large and significant reductions in sulphate and nitrate were recorded along with increases in marine salts, probably as a result of climatically related events. Qualitative, experimental and monitoring data from lochs in the Galloway area revealed evidence of recovery of fish populations. Interpretation of

  8. Water geochemistry of the Qiantangjiang River, East China: Chemical weathering and CO2 consumption in a basin affected by severe acid deposition

    Science.gov (United States)

    Liu, Wenjing; Shi, Chao; Xu, Zhifang; Zhao, Tong; Jiang, Hao; Liang, Chongshan; Zhang, Xuan; Zhou, Li; Yu, Chong

    2016-09-01

    The chemical composition of the Qiantangjiang River, the largest river in Zhejiang province in eastern China, was measured to understand the chemical weathering of rocks and the associated CO2 consumption and anthropogenic influences within a silicate-dominated river basin. The average total dissolved solids (TDS, 113 mg l-1) and total cation concentration (TZ+, 1357 μeq l-1) of the river waters are comparable with those of global major rivers. Ca2+ and HCO3- followed by Na2+ and SO42-, dominate the ionic composition of the river water. There are four major reservoirs (carbonates, silicates, atmospheric and anthropogenic inputs) contributing to the total dissolved load of the investigated rivers. The dissolved loads of the rivers are dominated by both carbonate and silicate weathering, which together account for about 76.3% of the total cationic load origin. The cationic chemical weathering rates of silicate and carbonate for the Qiantangjiang basin are estimated to be approximately 4.9 ton km-2 a-1 and 13.9 ton km-2 a-1, respectively. The calculated CO2 consumption rates with the assumption that all the protons involved in the weathering reaction are provided by carbonic acid are 369 × 103 mol km-2 a-1 and 273 × 103 mol km-2 a-1 by carbonate and silicate weathering, respectively. As one of the most severe impacted area by acid rain in China, H2SO4 from acid precipitation is also an important proton donor in weathering reactions. When H2SO4 is considered, the CO2 consumption rates for the river basin are estimated at 286 × 103 mol km-2 a-1 for carbonate weathering and 211 × 103 mol km-2 a-1 for silicate weathering, respectively. The results highlight that the drawdown effect of CO2 consumption by carbonate and silicate weathering can be largely overestimated if the role of sulfuric acid is ignored, especially in the area heavily impacted by acid deposition like Qiantangjiang basin. The actual CO2 consumption rates (after sulfuric acid weathering effect

  9. Different sources of omega-3 polyunsaturated fatty acids affects apparent digestibility, tissue deposition, and tissue oxidative stability in growing female rats

    Directory of Open Access Journals (Sweden)

    Benedito Vagner A

    2011-10-01

    Full Text Available Abstract Background Numerous health benefits associated with increased omega-3 polyunsaturated fatty acid (n-3 PUFA consumption has lead to an increasing variety of available n-3 PUFA sources. However, sources differ in the type, amount, and structural form of the n-3 PUFAs. Therefore, the objective of this study was to determine the effect of different sources of ω-3 PUFAs on digestibility, tissue deposition, eicosanoid metabolism, and oxidative stability. Methods Female Sprague-Dawley rats (age 28 d were randomly assigned (n = 10/group to be fed a high fat 12% (wt diet consisting of either corn oil (CO or n-3 PUFA rich flaxseed (FO, krill (KO, menhaden (MO, salmon (SO or tuna (TO oil for 8 weeks. Rats were individually housed in metabolic cages to determine fatty acid digestibility. Diet and tissue fatty acid composition was analyzed by gas chromatography and lipid classes using thin layer chromatography. Eicosanoid metabolism was determined by measuring urinary metabolites of 2-series prostaglandins (PGs and thromoboxanes (TXBs using enzyme immunoassays. Oxidative stability was assessed by measuring thiobarbituric acid reactive substances (TBARS and total antioxidant capacity (TAC using colorimetric assays. Gene expression of antioxidant defense enzymes was determined by real time quantitative polymerase chain reaction (RT-qPCR. Results Rats fed KO had significantly lower DHA digestibility and brain DHA incorporation than SO and TO-fed rats. Of the n-3 PUFA sources, rats fed SO and TO had the highest n-3 PUFAs digestibility and in turn, tissue accretion. Higher tissue n-3 LC-PUFAs had no significant effect on 2-series PG and TXB metabolites. Despite higher tissue n-3 LC-PUFA deposition, there was no increase in oxidation susceptibility indicated by no significant increase in TBARS or decrease in TAC and gene expression of antioxidant defense enzymes, in SO or TO-fed rats. Conclusions On the basis that the optimal n-3 PUFA sources should

  10. Boosting the performance of Pt electro-catalysts toward formic acid electro-oxidation by depositing sub-monolayer Au clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bi Xuanxuan; Wang Rongyue [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Ding Yi, E-mail: yding@sdu.edu.cn [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    2011-11-30

    Highlights: > Au decoration on Pt nanoparticles simultaneously increases the activity and stability. > Sub-monolayer Au decoration changes the reaction path and results in the activity improvement. > Increasing the Au coverage will increase the specific activity. > Proper Au coverage results in a maximum mass specific activity. - Abstract: CO poisoning is the main obstacle to the application of Pt nanoparticles as anode catalysts in direct formic acid fuel cells (DFAFCs). Significant types of Pt alloys have been investigated, which often demonstrate evidently improved catalytic performance governed by difference mechanisms. By using a well-known electrochemical technique of under potential deposition and in situ redox replacement, sub-monolayer Au clusters are deposited onto Pt nanoparticle surfaces in a highly controlled manner, generating a unique surface alloy structure. Under optimum conditions, the modified Pt nanoparticles can exhibit greatly enhanced specific activity (up to 23-fold increase) at potential of -0.2 V vs. MSE toward formic acid electro-oxidation (FAEO). Interestingly, the mass specific activity can also be improved by a factor of 2.3 at potential of -0.35 V vs. MSE although significant amount of surface Pt atoms are covered by the overlayer Au clusters. The much enhanced catalytic activity can be ascribed to a Pt surface ensemble effect, which induces change of the reaction path. Moreover, the sub-monolayer Au coating on the surface also contributes to the enhanced catalyst durability by inhibiting the Pt oxidation. These results show great potential to rationally design more active and stable nanocatalysts by modifying the Pt surface with otherwise inactive materials.

  11. Gradient Technology for High-Throughput Screening of Interactions between Cells and Nanostructured Materials

    Directory of Open Access Journals (Sweden)

    Andrew Michelmore

    2012-01-01

    Full Text Available We present a novel substrate suitable for the high-throughput analysis of cell response to variations in surface chemistry and nanotopography. Electrochemical etching was used to produce silicon wafers with nanopores between 10 and 100 nm in diameter. Over this substrate and flat silicon wafers, a gradient film ranging from hydrocarbon to carboxylic acid plasma polymer was deposited, with the concentration of surface carboxylic acid groups varying between 0.7 and 3% as measured by XPS. MG63 osteoblast-like cells were then cultured on these substrates and showed greatest cell spreading and adhesion onto porous silicon with a carboxylic acid group concentration between 2-3%. This method has great potential for high-throughput screening of cell-material interaction with particular relevance to tissue engineering.

  12. Complex Surface Concentration Gradients by Stenciled "Electro Click Chemistry"

    DEFF Research Database (Denmark)

    Hansen, Thomas Steen; Lind, Johan Ulrik; Daugaard, Anders Egede;

    2010-01-01

    Complex one- or two-dimensional concentration gradients of alkynated molecules are produced on azidized conducting polymer substrates by stenciled "electro click chemistry". The latter describes the local electrochemical generation of catalytically active Cu(I) required to complete a "click...... reaction" between alkynes and azides at room temperature. A stencil on the counter electrode defines the shape and multiplicity of the gradient(s) on the conducting polymer substrate, while the specific reaction conditions control gradient steepness and the maximum concentration deposited. Biologically...

  13. Response of alpine lakes and soils to changes in acid deposition: the MAGIC model applied to the Tatra Mountain region, Slovakia-Poland

    Directory of Open Access Journals (Sweden)

    Josef VESELÝ

    2004-02-01

    Full Text Available A dynamic process-based model of surface water acidification, MAGIC, was applied to 31 representative alpine lakes in the Tatra Mountains (~50% of all alpine lakes >0.3 ha in the lake-district. The model was calibrated to observed lake chemistry for the period 1980-2002. Surface water and soil chemistry were reconstructed from 1860 to 2002, given estimates of historical acid deposition, and forecast to 2020 based on the reduction in sulphur and nitrogen emissions presupposed by the Gothenburg Protocol. In the 1860s, all lakes were buffered by the carbonate system and only ~6% of lakes had acid neutralising capacity (ANC 50% of the SAA change in sensitive lakes with intermediate weathering rates and little soils (low BC exchangeable capacity and elevated terrestrial export of nitrate and (3 by parallel changes in concentrations of protons and aluminium (each ~20% of the SAA change in extremely sensitive lakes, with the lowest weathering rates and soil base saturation. The full implementation of the Gothenburg Protocol will not be sufficient to allow recovery of the latter group of lakes, which will remain acidified after 2020.

  14. Effects of acidic deposition on in-lake phosphorus availability: a lesson from lakes recovering from acidification.

    Science.gov (United States)

    Kopáček, Jiří; Hejzlar, Josef; Kaňa, Jiří; Norton, Stephen A; Stuchlík, Evžen

    2015-03-01

    Lake water concentrations of phosphorus (P) recently increased in some mountain areas due to elevated atmospheric input of P rich dust. We show that increasing P concentrations also occur during stable atmospheric P inputs in central European alpine lakes recovering from atmospheric acidification. The elevated P availability in the lakes results from (1) increasing terrestrial export of P accompanying elevated leaching of dissolved organic carbon and decreasing phosphate-adsorption ability of soils due to their increasing pH, and (2) decreasing in-lake P immobilization by aluminum (Al) hydroxide due to decreasing leaching of ionic Al from the recovering soils. The P availability in the recovering lakes is modified by the extent of soil acidification, soil composition, and proportion of till and meadow soils in the catchment. These mechanisms explain several conflicting observations of the acid rain effects on surface water P concentrations.

  15. Effects of acidic deposition on in-lake phosphorus availability: a lesson from lakes recovering from acidification.

    Science.gov (United States)

    Kopáček, Jiří; Hejzlar, Josef; Kaňa, Jiří; Norton, Stephen A; Stuchlík, Evžen

    2015-03-01

    Lake water concentrations of phosphorus (P) recently increased in some mountain areas due to elevated atmospheric input of P rich dust. We show that increasing P concentrations also occur during stable atmospheric P inputs in central European alpine lakes recovering from atmospheric acidification. The elevated P availability in the lakes results from (1) increasing terrestrial export of P accompanying elevated leaching of dissolved organic carbon and decreasing phosphate-adsorption ability of soils due to their increasing pH, and (2) decreasing in-lake P immobilization by aluminum (Al) hydroxide due to decreasing leaching of ionic Al from the recovering soils. The P availability in the recovering lakes is modified by the extent of soil acidification, soil composition, and proportion of till and meadow soils in the catchment. These mechanisms explain several conflicting observations of the acid rain effects on surface water P concentrations. PMID:25660534

  16. Modification of polylactic acid surface using RF plasma discharge with sputter deposition of a hydroxyapatite target for increased biocompatibility

    Science.gov (United States)

    Tverdokhlebov, S. I.; Bolbasov, E. N.; Shesterikov, E. V.; Antonova, L. V.; Golovkin, A. S.; Matveeva, V. G.; Petlin, D. G.; Anissimov, Y. G.

    2015-02-01

    Surface modification of polylactic acid (PLLA) by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering was investigated. Increased biocompatibility was demonstrated using studies with bone marrow multipotent mesenchymal stromal cells. Atomic force microscopy demonstrates that the plasma treatment modifies the surface morphology of PLLA to produce rougher surface. Infrared spectroscopy and X-ray diffraction revealed that changes in the surface morphology are caused by the processes of PLLA crystallization. Fluorescent X-ray spectroscopy showed that the plasma treatment also changes the chemical composition of PLLA, enriching it with ions of the sputtered target: calcium, phosphorus and oxygen. It is hypothesized that these surface modifications increase biocompatibility of PLLA without increasing toxicity.

  17. Comparative sensitivity, mechanisms, and whole plant physiological implications of responses of loblolly pine genotypes to ozone and acid deposition

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, S.B.; Adams, M.B.; Edwards, N.T.; Hanson, P.J.; Layton, P.A.; O' Neill, E.G.; Roy, W.K.

    1988-09-01

    A quantitative and mechanistic basis for evaluating the potential effects of atmospheric pollutants on physiology and growth of seedlings of loblolly pine, an important timber species in southern commercial forests, was evaluated in laboratory and controlled field studies. Fifty-three half-sib families of loblolly pine were examined. Primary objectives were to (1) quantify differences in growth responses of these 53 half-sib families to the individual and interactive effects of simulated acid rain and ozone in the field, (2) characterize the physiological basis of observed responses in field and laboratory studies, (3) compare and contrast results obtained with similar experimental protocols in field and laboratory approaches, and (4) develop experimental protocols for quantifying physiological and growth responses of large trees in the field. 152 refs., 41 figs., 42 tabs.

  18. Second gradient poromechanics

    CERN Document Server

    Sciarra, Giulio; Coussy, Olivier

    2010-01-01

    Second gradient theories have been developed in mechanics for treating different phenomena as capillarity in fluids, plasticity and friction in granular materials or shear band deformations. Here, there is an attempt of formulating a second gradient Biot like model for porous materials. In particular the interest is focused in describing the local dilatant behaviour of a porous material induced by pore opening elastic and capillary interaction phenomena among neighbouring pores and related micro-filtration phenomena by means of a continuum microstructured model. The main idea is to extend the classical macroscopic Biot model by including in the description second gradient effects. This is done by assuming that the surface contribution to the external work rate functional depends on the normal derivative of the velocity or equivalently assuming that the strain work rate functional depends on the porosity and strain gradients. According to classical thermodynamics suitable restrictions for stresses and second g...

  19. Gradient Particle Magnetohydrodynamics

    OpenAIRE

    Maron, Jason L.; Howes, Gregory G.

    2001-01-01

    We introduce Gradient Particle Magnetohydrodynamics (GPM), a new Lagrangian method for magnetohydrodynamics based on gradients corrected for the locally disordered particle distribution. The development of a numerical code for MHD simulation using the GPM algorithm is outlined. Validation tests simulating linear and nonlinear sound waves, linear MHD waves, advection of magnetic fields in a magnetized vortex, hydrodynamical shocks, and three-dimensional collapse are presented, demonstrating th...

  20. Analysis of potential combustion source impacts on acid deposition using an independently derived inventory. Volume II, appendices

    Energy Technology Data Exchange (ETDEWEB)

    1983-12-01

    This document contains 2 appendices. The first documents the methodologies used to calculate production, unit energy consumption, fuel type and emission estimates for 16 industries and 35 types of facilities utilizing direct-fired industrial combustion processes, located in 26 states (and the District of Columbia) east of the Mississippi River. As discussed in the text of this report, a U.S. total of 16 industries and 45 types of facilities utilizing direct-fired combustion processes were identified by an elimination type method that was developed based on evaluation of fuel use in industrial SIC codes 20-39 to identify pollutant sources contributing to acid rain. The final population included only plants that have direct-fired fuel consumption greater than or equal to 100 x 10/sup 9/ Btu/yr of equivalent energy consumption. The goal for this analysis was to provide at least a 1980 base year for the data. This was achieved for all of the industries and in fact, 1981 data were used for a number of the industries evaluated. The second contains an analysis of all consumption of major fossil fuels to: (1) identify all fuel usage categories, and (2) identify the kinds of combustion equipment used within each category. This analysis provides a frame of reference for the balance of the study and permits using an energy accounting methodology to quantify the degree to which the inventoried sources in individual consuming sectors are complete and representative of the total population for the sector.

  1. Mineralogy of evaporite deposits on Mars: Constraints from laboratory, field, and remote measurements of analog terrestrial acid saline lakes

    Science.gov (United States)

    Bridges, N.; Núñez, J. I.; Seelos, F. P., IV; Hook, S. J.; Baldridge, A. M.; Thomson, B. J.

    2015-12-01

    Remote compositional data from imaging spectrometers such as CRISM, OMEGA, and TES, and high-resolution imagery from MOC, CTX, and HiRISE have provided invaluable information for improving our understanding of the composition and geologic history of the martian surface and identifying potential past and present habitable environments on Mars. Simulated CRISM spectra and summary parameter maps and HiRISE color images were generated using airborne hyperspectral data of two acid-saline lakes in Western Australia. These locations are applicable to Mars, as they contain a suite of clays, sulfates, and salts formed under variable pH and salinity - mineralogies similar to those observed in Noachian and Hesperian terrain. The remote datasets were used to make surface composition predictions which were then verified through field study and sample analysis. We find phyllosilicates intermixed with sulfates in sulfate-rich surfaces exhibit variable spectral responses, even for similar conditions and abundances seen in the field. Where sulfates, such as gypsum and alunite, are found, phyllosilicates are intermixed or reside beneath the surface yet are not always detected. This suggests that geologic complexities may mask phyllosilicate detection at or near the surface on Mars where only sulfates have so far been found.

  2. Modification of polylactic acid surface using RF plasma discharge with sputter deposition of a hydroxyapatite target for increased biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Tverdokhlebov, S.I., E-mail: tverd@tpu.ru [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Bolbasov, E.N.; Shesterikov, E.V. [Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk 634050 (Russian Federation); Antonova, L.V.; Golovkin, A.S.; Matveeva, V.G. [Federal State Budgetary Institution Research Institute for Complex Issues of Cardiovascular Disease, 6 Sosnovy Blvd, Kemerovo 650002 (Russian Federation); Petlin, D.G.; Anissimov, Y.G. [Griffith University, School of Natural Sciences, Engineering Dr., Southport, QLD 4222 (Australia)

    2015-02-28

    Highlights: • The treatment by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering improves the biocompatibility of PLLA surface. • The treatment significantly increases the roughness of PLLA surface. • The formation of rough highly porous surface is due to the etching and crystallization processes on PLLA surface during treatment. • Maximum concentration of the ions from the sputtered target is achieved at 60 s of the plasma treatment. - Abstract: Surface modification of polylactic acid (PLLA) by plasma of radio-frequency magnetron discharge with hydroxyapatite target sputtering was investigated. Increased biocompatibility was demonstrated using studies with bone marrow multipotent mesenchymal stromal cells. Atomic force microscopy demonstrates that the plasma treatment modifies the surface morphology of PLLA to produce rougher surface. Infrared spectroscopy and X-ray diffraction revealed that changes in the surface morphology are caused by the processes of PLLA crystallization. Fluorescent X-ray spectroscopy showed that the plasma treatment also changes the chemical composition of PLLA, enriching it with ions of the sputtered target: calcium, phosphorus and oxygen. It is hypothesized that these surface modifications increase biocompatibility of PLLA without increasing toxicity.

  3. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  4. High Gradient Accelerator Research

    Energy Technology Data Exchange (ETDEWEB)

    Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Physics. Plasma Science and Fusion Center

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low power microwave cold test and high power, high gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  5. Uniform gradient expansions

    Energy Technology Data Exchange (ETDEWEB)

    Giovannini, Massimo, E-mail: massimo.giovannini@cern.ch [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland); INFN, Section of Milan-Bicocca, 20126 Milan (Italy)

    2015-06-30

    Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.

  6. Learning gradients on manifolds

    CERN Document Server

    Mukherjee, Sayan; Zhou, Ding-Xuan; 10.3150/09-BEJ206

    2010-01-01

    A common belief in high-dimensional data analysis is that data are concentrated on a low-dimensional manifold. This motivates simultaneous dimension reduction and regression on manifolds. We provide an algorithm for learning gradients on manifolds for dimension reduction for high-dimensional data with few observations. We obtain generalization error bounds for the gradient estimates and show that the convergence rate depends on the intrinsic dimension of the manifold and not on the dimension of the ambient space. We illustrate the efficacy of this approach empirically on simulated and real data and compare the method to other dimension reduction procedures.

  7. Improved sensing of dopamine and ascorbic acid using a glassy carbon electrode modified with electrochemically synthesized nickel-cobalt hexacyanoferrate microparticles deposited on graphene

    International Nuclear Information System (INIS)

    We report on the preparation of a nanocomposite by an electrochemical redox reaction in which graphene oxide is reduced to graphene while nickel-cobalt hexacyanoferrate (III) microparticles are simultaneously formed by oxidation. The microparticles deposit uniformly on the surface of graphene sheets, and the resulting nanocomposite was characterized by scanning electron microscopy, energy dispersive X-ray studies, cyclic voltammetry, and differential pulse voltammetry. Electrochemical studies using a glassy carbon electrode showed the material to possess superior electrocatalytic activity in terms of the oxidation of dopamine (DA) and ascorbic acid (AA). Calibration plots were established for DA in the concentration range from 0.2 to 500 μM (at a potential of 280 mV), and for AA from 0.5 to 200 μM and from 200 to 2,000 μM, (at a potential of 100 mV). These linear ranges are much wider than those of most modified electrodes reported before. (author)

  8. Nonlinear optical studies on 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    Science.gov (United States)

    Matei, Andreea; Marinescu, Maria; Constantinescu, Catalin; Ion, Valentin; Mitu, Bogdana; Ionita, Iulian; Dinescu, Maria; Emandi, Ana

    2016-06-01

    We present results on a new, laboratory synthesized ferrocene-derivative, i.e. 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid. Thin films with controlled thickness are deposited by matrix-assisted pulsed laser evaporation (MAPLE), on quartz and silicon substrates, with the aim of evaluating the nonlinear optical properties for potential optoelectronic applications. Dimethyl sulfoxide was used as matrix, with 1% wt. concentration of the guest compound. The frozen target is irradiated by using a Nd:YAG laser (4ω/266 nm, 7 ns pulse duration, 10 Hz repetition rate), at low fluences ranging from 0.1 to 1 J/cm2. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to probe the surface morphology of the films. Fourier transform infrared (FTIR) and Raman spectroscopy reveal similar structure of the thin film material when compared to the starting material. The optical properties of the thin films are investigated by spectroscopic-ellipsometry (SE), and the refractive index dependence with respect to temperature is studied. The second harmonic generation (SHG) potential is assessed by using a femtosecond Ti:sapphire laser (800 nm, 60-100 fs pulse duration, 80 MHz repetition rate), at 200 mW maximum output power, revealing that the SHG signal intensity is strongly influenced by the films' thickness.

  9. Roles of humidity and heat treatment temperatures on YBa2Cu3O7-x coated conductors by trifluoroacetic acid-metal organic deposition process

    Institute of Scientific and Technical Information of China (English)

    Seok-Hern JANG; Jun-Hyung LIM; Chang-Min LEE; Eui-Cheol PARK; Soo-Min HWANG; Jun-Hyuk CHOI; Jong-Hyun SHIM; Jin-Hyun PARK; Won KIM; Jinho JOO

    2009-01-01

    YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition (TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure, degree of texture and critical properties of the films were evaluated. In order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties, heat-treatment was performed at various temperatures with the other processing variables fixed. The films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 atmosphere. The texture was determined by pole-figure analysis. The amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere, which led to increased critical properties. In addition, the microstructure varied significantly with firing temperature but changed little with calcining temperature. The highest IC of 40 A/cm-width, which corresponds to JC value of 1.8 MA/cm2, was obtained for the films fired at 775 ℃ (in 12.1% humidity) after calcining at 400-430 ℃. It is likely that the highest IC value is due to the formation of a more pure YBCO phase, c-axis grains, and a denser microstructure.

  10. Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid deposition in high-fat diet-induced obese rats

    Directory of Open Access Journals (Sweden)

    Eu Chia

    2010-07-01

    Full Text Available Abstract Background The metabolic syndrome, known also as the insulin resistance syndrome, refers to the clustering of several risk factors for atherosclerotic cardiovascular disease. Dyslipidaemia is a hallmark of the syndrome and is associated with a whole body reduction in the activity of lipoprotein lipase (LPL, an enzyme under the regulation of the class of nuclear receptors known as peroxisome proliferator-activated receptor (PPAR. Glycyrrhizic acid (GA, a triterpenoid saponin, is the primary bioactive constituent of the roots of the shrub Glycyrrhiza glabra. Studies have indicated that triterpenoids could act as PPAR agonists and GA is therefore postulated to restore LPL expression in the insulin resistant state. Results Oral administration of 100 mg/kg of GA to high-fat diet-induced obese rats for 28 days led to significant reduction in blood glucose concentration and improvement in insulin sensitivity as indicated by the homeostasis model assessment of insulin resistance (HOMA-IR (p Conclusion In conclusion, GA may be a potential compound in improving dyslipidaemia by selectively inducing LPL expression in non-hepatic tissues. Such up-regulation was accompanied by a GA-mediated improvement in insulin sensitivity, which may be associated with a decrease in tissue lipid deposition. The HDL-raising effect of GA suggests the antiatherosclerotic properties of GA.

  11. Manipulating the Gradient

    Science.gov (United States)

    Gaze, Eric C.

    2005-01-01

    We introduce a cooperative learning, group lab for a Calculus III course to facilitate comprehension of the gradient vector and directional derivative concepts. The lab is a hands-on experience allowing students to manipulate a tangent plane and empirically measure the effect of partial derivatives on the direction of optimal ascent. (Contains 7…

  12. Weathering Processes Across Extreme Erosional Gradients: Do Landslides Matter?

    Science.gov (United States)

    Emberson, R.; Hovius, N.; Galy, A.; Marc, O.

    2015-12-01

    A process-based understanding of weathering in actively eroding mountain belts is vital to understand how linkages between erosion and weathering affect global biogeochemical cycles on a range of timescales. Here we present surface water chemistry data from Southern Taiwan that demonstrates the impact of variable erosive processes on weathering budgets on a large range of scales, from tens of metres to large catchments (>50km2). Southern Taiwan is an excellent example of a number of gradients in erosive processes, with relief and median slope increasing from the southernmost small hills to mountainous threshold-hillslopes with up to 2.5km of relief approximately 100km to the north. Furthermore, Typhoon Morakot (2009) triggered extremely extensive landsliding in some catchments within this zone, allowing distinctions to be drawn between average topographic characteristics of catchments and the erosive processes (i.e. mass wasting) at work therein. Landslides play an important role in localising weathering in deposits with high internal surface area and slow throughflow of fluids, creating sites of rapid weathering which can be a first order control on catchment solute budgets in watersheds where landslides deposits and scars exceed 2% of drained area. Variation in the detailed chemistry of landslide seepages - particularly the carbonate/silicate weathering balance - indicates that this process has a different impact on inorganic weathering-driven carbon cycling than slower erosive processes; a strong positive correlation between landslide-affected area and Ca2+:Si ratios on catchment scale suggests rapid erosion is not strongly coupled to CO2 drawdown. Rapid oxidation of sulphides - ubiquitous in many rapidly eroding mountain belts - within highly fragmented landslide deposits, and associated sulphuric-acid driven weathering, further complicates the effect landsliding has on the carbon cycle.

  13. Composition Gradient Hard Coatings by Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    CHEN Jun; LIN Guo-qiang; WANG Fu-gang

    2004-01-01

    Arc Ion Plating can be used to synthesize multi-component composition gradient hard coatings by adjusting arc currents of metal targets. The present work aims at a comprehensive description of such a technique. The examples of TiAl multi-layer alloy coatings and (Ti, M) N composition-gradient films were taken (M representing Zr, Nb etc.) for the purpose of explaining the working process and evaluating practical effects. The results show that this technique has the advantages of easy manipulation, rapid deposition, and wide composition range.Key Words: Arc Ion plating, hard coating, composition gradient coatings

  14. Energy in density gradient

    OpenAIRE

    Vranjes, J.; Kono, M

    2015-01-01

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in partic...

  15. Increasing SLEDed Linac Gradient

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Zoltan D

    2001-11-08

    This note will show how to increase the SLED [1] gradient by varying Q{sub e}, the external Q of the SLED cavity, by increasing its Q{sub 0} and by increasing the compression ratio. If varying the external Q is to be effective, then the copper losses should be small so that Q{sub 0} >> Q{sub e}. Methods of varying Q{sub e} will be indicated but no experimental data will be presented. If we increase the klystron pulse width from 3.5 to 5 {micro}S and increase Q{sub 0} from the present 100000 to 300000, then the gradient increases by 19% and the beam energy increases from 50 to 60 GeV. This note will also discuss SLED operation at 11424 MHz, the NLC frequency. Without Q{sub e} switching, using SLED at 11424 MHz increases the SLAC gradient from 21 MV/m to 34 MV/m, and at the same repetition rate, uses about 1/5 of rf average power. If we also double the compression ratio, we reach 47 MV/m and over 100 GeV beam energy.

  16. Phytopigments and fatty acids in the gut of the deposit-feeding heart urchin Echinocardium cordatum in the southern North Sea: Selective feeding and its contribution to the benthic carbon budget

    Science.gov (United States)

    Boon, Arjen R.; Duineveld, Gerard C. A.

    2012-01-01

    As part of a broader study on benthic-pelagic coupling in the southern North Sea, specimens of the common heart urchin Echinocardium cordatum were sampled for analyses on phytopigments and fatty acids in their guts. Results were interpreted in the context of feeding and ecological functioning of the heart urchins in the benthic system. Ingestion selection factors for both component groups were relatively high, 5 to 9 for chlorophyll a and 9 to 130 for total fatty acids. The data point to at least partially different sources of the pigments and of the fatty acids. Next to algal detritus, small infauna relatively rich in fatty acids might be preferentially co-ingested with the detritus. Due to digestive breakdown and absorption, the concentrations of pigments and fatty acids were importantly decreased, indicating a rather high digestion efficiency for this subsurface deposit feeder, up to 80%. The results indicate that E. cordatum increases its energy acquisition by strong selectivity and a high digestive efficiency. Optimal foraging is likely to apply on deposit-feeding invertebrates in relatively food-rich coastal environments as much as it does in the food-poor deep-sea environment. Using chlorophyll a as a proxy for carbon, the contribution of the urchin population to the momentary benthic carbon budget was calculated at 7% to 42%.

  17. Reinforcement Learning by Value Gradients

    CERN Document Server

    Fairbank, Michael

    2008-01-01

    The concept of the value-gradient is introduced and developed in the context of reinforcement learning. It is shown that by learning the value-gradients exploration or stochastic behaviour is no longer needed to find locally optimal trajectories. This is the main motivation for using value-gradients, and it is argued that learning value-gradients is the actual objective of any value-function learning algorithm for control problems. It is also argued that learning value-gradients is significantly more efficient than learning just the values, and this argument is supported in experiments by efficiency gains of several orders of magnitude, in several problem domains. Once value-gradients are introduced into learning, several analyses become possible. For example, a surprising equivalence between a value-gradient learning algorithm and a policy-gradient learning algorithm is proven, and this provides a robust convergence proof for control problems using a value function with a general function approximator.

  18. 河口盐度梯度下溶解态核酸的微生物可利用性%Microbial Bioavailability of Dissolved Nucleic Acids Across the Estuarine Salinity Gradient

    Institute of Scientific and Technical Information of China (English)

    杨青青; 李朋辉; 黄清辉

    2013-01-01

    As an important component of dissolved organic matter (DOM),nucleic acids (DNA and RNA) are essential nutrient and energy sources in aquatic microbial food web.Therefore,it is important to understand the bioavailability of nucleic acids.The bioavailability of nucleic acids was investigated by a batch of incubation experiments,adding fish DNA and yeast RNA into water samples with different salinity collected from the Yangtze River estuary in the spring of 2012.According to the results,20%-50% of dissolved DNA was transformed into particulate DNA quickly with the conversion rates increasing with salinity,only 10% dissolved RNA was transformed into particulate RNA and the salinity had no effect on the conversation rates.In each incubation experiment,the microbial utilization kinetic curves of dissolved nucleic acids were fitted to the Sigmoid model.There were lag periods of 30-80 hours followed by the rapid utilization phase and then the stagnation phase.The results also showed that the bacteria in seawater had higher maximum utilization rate than the bacteria in estuarine and fresh water.Dissolved nucleic acids spiked in estuarine water can be bound to colloids and particles at some extent,only those free dissolved or enzymatically hydrolysable forms are bioavailable.The percentage of bioavailable RNA (80%-90%) was significantly higher than that of bioavailable DNA and it did not change significantly with salinity while the percent of bioavailable DNA decreased from 78% to 50% with salinity.Therefore,the speciation and bioavailability are significantly different between DNA and RNA across the estuarine salinity gradient.%核酸物质(DNA和RNA)作为自然水体中重要的溶解有机质组分之一,是水生微生物食物网的重要物质基础,因此核酸的微生物可利用性具有重要研究意义.2012年春季从长江口不同盐度区域采集水样,并分别添加鱼类DNA和酵母RNA进行培养,考察了其微生物可利用性.结果

  19. Sulfur Fractions in Typic Udalfs in Forest Ecosystem in Mt. Lushan as Affected by Acid Deposition.%酸沉降影响下庐山森林生态系统土壤硫形态分布研究

    Institute of Scientific and Technical Information of China (English)

    石盛莉; 潘根兴; 王连峰; 张乐华; 黄明星

    2001-01-01

    Acid deposition has been a severe environmental pollution problem in Mt. Lushan since early 1980, Soil acidification trends have been resultantly obvious. Pedons of the Typic Udalfs both under deciduous and coniferous forest with and without root-growing effects were sampled. Soil sulfur was fractionated by selective extraction methods and the sulfur in solutions was determined by BaSO4 turbidimetry. The results showed the total S in surface layers amounted to 400-800mg*kg-1, indicating a high net accumulation of S under impacts of the acid deposition. The sulfur in the soils were predominated by adsorbed sulfur(160.0±72.1mg*kg-1) and organic sulfur(123.3±142.9 mg*kg-1), with the former accumulating to deep profile and the latter in surface 0-30 cm depth. Under deciduous soil sulfur accumulated to deep profile. Adsorbed sulfur under coniferous was higher (152.72 mg*kg-1) than which under deciduous (121.85 mg*kg-1), while the latter contained more water sulfur, indicating sulfur under deciduous inclined to move. Soils with root-growing effects contained more total sulfur (351.15 mg*kg-1) than soil without root-growing effects (300.50 mg*kg-1), high organic sulfur accumulated in soils in root-growing depth, but no significant profile difference under deciduous. Therefore, the sulfur transform was involved in accumulation of sulfur affected by acid deposition.

  20. Gradient equivalent crystal theory.

    Science.gov (United States)

    Zypman, F R; Ferrante, J

    2006-07-01

    This paper presents an extension of the formalism of equivalent crystal theory (ECT) by introducing an electron density gradient term so that the total model density becomes a more accurate representation of the real local density. Specifically, we allow for the electron density around a lattice site to have directionality, in addition to an average value, as assumed in ECT. We propose that an atom senses its neighbouring density as a weighted sum-the weights given by the its own electronic probability. As a benchmark, the method is used to compute vacancy migration energy curves of iron. These energies are in good agreement with previously published results. PMID:21690822

  1. Energy in density gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J., E-mail: jvranjes@yahoo.com [Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife (Spain); Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain); Kono, M., E-mail: kono@fps.chuo-u.ac.jp [Faculty of Policy Studies, Chuo University, Tokyo (Japan)

    2015-01-15

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  2. Nitrogen deposition effects on carbon storage and fungal:bacterial ratios in coastal sage scrub soils of southern California.

    Science.gov (United States)

    Liu, Kun; Crowley, David

    2009-01-01

    The effects of nitrogen (N) across a deposition gradient on bacterial and fungal degradation pathways were studied in southern California coastal sage scrub soils to determine whether elevated N levels alter microbial community structure and organic matter accumulation. Three sites across an N deposition gradient having low, intermediate, and high levels of atmospheric N deposition were studied for 20 mo. Fungi:bacteria (F:B) biomass ratios were determined by phospholipid fatty acid analysis. Plots at each location included control plots receiving ambient N deposition and treatment plots that were fertilized with an additional 50 kg N ha(-1) yr(-1) of slow-release urea. Results showed that organic carbon (C) levels varied seasonally but that F:B ratios were relatively stable and similar across the three locations and over time. Total organic C decreased in response to N additions only at the low N deposition site. The results suggest that organic matter degradation pathways leading to C storage in soils that have been exposed to high levels of atmospheric N deposition are not responsive to additional increases in N and that N effects on organic C in semiarid soils may be significant only in areas with prior low exposure to N pollution.

  3. Regional assessment of the response of the acid-base status of lake watersheds in the Adirondack region of New York to changes in atmospheric deposition using PnET-BGC.

    Science.gov (United States)

    Chen, Limin; Driscoll, Charles T

    2005-02-01

    Understanding the response of soil and surface waters to changes in atmospheric deposition is critical for guiding future legislation on air pollution. The Adirondack region of New York experiences among the most severe ecological impacts from acidic deposition. The region is characterized by considerable variability in atmospheric deposition, surficial and bedrock geology, hydrologic flow paths, and vegetation resulting in variability in effects of acidic deposition. In this study, an integrated biogeochemical model (PnET-BGC) was applied to 37 forest lake watersheds to assess the response of soil and surface waters of the Adirondacks to changes in atmospheric deposition at a regional scale. Model-simulated surface water chemistry was validated against data from two synoptic surveys conducted in 1984 and 2001. Results indicate that the model is able to capture the observed changes in surface water chemistry during this period. The model was further used to forecast the response of soil and surface waters to three future emission control scenarios. Results indicate that under the Clean Air Act, surface water SO4(2-) concentrations will continue to decrease at a median rate of -0.38 microeq/L-yr, and surface water ANC is predicted to increase at a median rate of 0.11 microeq/L-yr. More aggressive emission reductions will accelerate the rate of recovery. Under an aggressive control scenario, which represents an additional 75% reduction in SO2 emissions beyond the implementation of the Clean Air Act, surface water SO4(2-) concentrations are predicted to decrease at a median rate of -0.88 microeq/L-yr, and surface water ANC is predicted to increase at a median rate of 0.43 microeq/L-yr. Model predictions of several biologically relevant chemical indicators are also reported.

  4. The Consistency of Isotopologues of Ambient Atmospheric Nitric Acid in Passively Collected Samples

    Science.gov (United States)

    Bell, M. D.; Sickman, J. O.; Bytnerowicz, A.; Padgett, P.; Allen, E. B.

    2012-12-01

    Anthropogenic sources of nitrogen oxides have previously been shown to have distinctive isotopic signatures of oxygen and nitrogen. Nylon filters are currently used in passive sampling arrays to measure ambient atmospheric nitric acid concentrations and estimate deposition rates. This experiment measured the ability of nylon filters to consistently collect isotopologues of atmospheric nitric acid in the same ratios as they are present in the atmosphere. Samplers were deployed in continuous stirred tank reactors (CSTR) and at field sites across a nitrogen deposition gradient in Southern California. Filters were exposed over a four week period with individual filters being subjected to 1-4 week exposure times. Extracted nitric acid were measured for δ18O and δ15N ratios and compared for consistency based on length of exposure and amount of HNO3 collected. Filters within the CSTRs collected HNO3 at a consistent rate in both high and low concentration chambers. After two weeks of exposure, the mean δ18O values were within 0.5‰ of the δ18O of the source HNO3 solution. The mean of all weekly exposures were within 0.5‰ of the δ15N of the source solution, but after three weeks, the mean δ15N of adsorbed HNO3 was within 0.2‰. As the length of the exposure increased, the variability of measured delta values decreased for both elements. The field samplers collected HNO3 consistent with previously measured values along a deposition gradient. The mean δ18O at high deposition sites was 52.2‰ compared to 35.7‰ at the low deposition sites. Mean δ15N values were similar at all sites across the deposition gradient. Due to precipitation events occurring during the exposure period, the δ15N and δ18O of nitric acid were highly variable at all field sites. At single sites, changes in δ15N and δ18O were negatively correlated, consistent with two-sourcing mixing dynamics, but the slope of the regressions differed between high and low deposition sites. Anthropogenic

  5. Echium oil increased the expression of a Δ4 Fads2 fatty acyl desaturase and the deposition of n-3 long-chain polyunsaturated fatty acid in comparison with linseed oil in striped snakehead (Channa striata) muscle.

    Science.gov (United States)

    Jaya-Ram, Annette; Shu-Chien, Alexander Chong; Kuah, Meng-Kiat

    2016-08-01

    Despite the potential of vegetable oils as aquafeed ingredients, a major drawback associated with their utilization is the inferior level of beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Echium oil (EO), which is rich in stearidonic acid (SDA, 18:4n-3), could potentially improve the deposition of n-3 LC-PUFA as the biosynthesis of LC-PUFA is enhanced through bypassing the rate-limiting ∆6 desaturation step. We report for the first time an attempt to investigate whether the presence of a desaturase (Fads2) capable of ∆4 desaturation activities and an elongase (Elovl5) will leverage the provision of dietary SDA to produce a higher rate of LC-PUFA bioconversion. Experimental diets were designed containing fish oil (FO), EO or linseed oil (LO) (100FO, 100EO, 100LO), and diets which comprised equal mixtures of the designated oils (50EOFO and 50EOLO) were evaluated in a 12-week feeding trial involving striped snakeheads (Channa striata). There was no significant difference in growth and feed conversion efficiency. The hepatic fatty acid composition and higher expression of fads2 and elovl5 genes in fish fed EO-based diets indicate the utilization of dietary SDA for LC-PUFA biosynthesis. Collectively, this resulted in a higher deposition of muscle eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) compared to LO-based diets. Dietary EO improved the ratio of n-3 LC-PUFA to n-6 LC-PUFA in fish muscle, which is desirable for human populations with excessive consumption of n-6 PUFA. This study validates the contribution of SDA in improving the content of n-3 LC-PUFA and the ratio of EPA to arachidonic acid (ARA, 20:4n-6) in a freshwater carnivorous species.

  6. Echium oil increased the expression of a Δ4 Fads2 fatty acyl desaturase and the deposition of n-3 long-chain polyunsaturated fatty acid in comparison with linseed oil in striped snakehead (Channa striata) muscle.

    Science.gov (United States)

    Jaya-Ram, Annette; Shu-Chien, Alexander Chong; Kuah, Meng-Kiat

    2016-08-01

    Despite the potential of vegetable oils as aquafeed ingredients, a major drawback associated with their utilization is the inferior level of beneficial n-3 long-chain polyunsaturated fatty acids (LC-PUFA). Echium oil (EO), which is rich in stearidonic acid (SDA, 18:4n-3), could potentially improve the deposition of n-3 LC-PUFA as the biosynthesis of LC-PUFA is enhanced through bypassing the rate-limiting ∆6 desaturation step. We report for the first time an attempt to investigate whether the presence of a desaturase (Fads2) capable of ∆4 desaturation activities and an elongase (Elovl5) will leverage the provision of dietary SDA to produce a higher rate of LC-PUFA bioconversion. Experimental diets were designed containing fish oil (FO), EO or linseed oil (LO) (100FO, 100EO, 100LO), and diets which comprised equal mixtures of the designated oils (50EOFO and 50EOLO) were evaluated in a 12-week feeding trial involving striped snakeheads (Channa striata). There was no significant difference in growth and feed conversion efficiency. The hepatic fatty acid composition and higher expression of fads2 and elovl5 genes in fish fed EO-based diets indicate the utilization of dietary SDA for LC-PUFA biosynthesis. Collectively, this resulted in a higher deposition of muscle eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) compared to LO-based diets. Dietary EO improved the ratio of n-3 LC-PUFA to n-6 LC-PUFA in fish muscle, which is desirable for human populations with excessive consumption of n-6 PUFA. This study validates the contribution of SDA in improving the content of n-3 LC-PUFA and the ratio of EPA to arachidonic acid (ARA, 20:4n-6) in a freshwater carnivorous species. PMID:26842427

  7. Charge gradient microscopy

    Science.gov (United States)

    Hong, Seungbum; Tong, Sheng; Park, Woon Ik; Hiranaga, Yoshiomi; Cho, Yasuo; Roelofs, Andreas

    2014-01-01

    Here we present a simple and fast method to reliably image polarization charges using charge gradient microscopy (CGM). We collected the current from the grounded CGM probe while scanning a periodically poled lithium niobate single crystal and single-crystal LiTaO3 thin film on the Cr electrode. We observed current signals at the domains and domain walls originating from the displacement current and the relocation or removal of surface charges, which enabled us to visualize the ferroelectric domains at a scan frequency above 78 Hz over 10 μm. We envision that CGM can be used in high-speed ferroelectric domain imaging and piezoelectric energy-harvesting devices. PMID:24760831

  8. Bioelectric and Morphological Response of Liquid-Covered Human Airway Epithelial Calu-3 Cell Monolayer to Periodic Deposition of Colloidal 3-Mercaptopropionic-Acid Coated CdSe-CdS/ZnS Core-Multishell Quantum Dots.

    Directory of Open Access Journals (Sweden)

    Aizat Turdalieva

    Full Text Available Lung epithelial cells are extensively exposed to nanoparticles present in the modern urban environment. Nanoparticles, including colloidal quantum dots (QDs, are also considered to be potentially useful carriers for the delivery of drugs into the body. It is therefore important to understand the ways of distribution and the effects of the various types of nanoparticles in the lung epithelium. We use a model system of liquid-covered human airway epithelial Calu-3 cell cultures to study the immediate and long-term effects of repeated deposition of colloidal 3-mercaptopropionic-acid coated CdSe-CdS/ZnS core-multishell QDs on the lung epithelial cell surface. By live confocal microscope imaging and by QD fluorescence measurements we show that the QD permeation through the mature epithelial monolayers is very limited. At the time of QD deposition, the transepithelial electrical resistance (TEER of the epithelial monolayers transiently decreased, with the decrement being proportional to the QD dose. Repeated QD deposition, once every six days for two months, lead to accumulation of only small amounts of the QDs in the cell monolayer. However, it did not induce any noticeable changes in the long-term TEER and the molecular morphology of the cells. The colloidal 3-mercaptopropionic-acid coated CdSe-CdS/ZnS core-multishell QDs could therefore be potentially used for the delivery of drugs intended for the surface of the lung epithelia during limited treatment periods.

  9. Generalized conjugate gradient squared

    Energy Technology Data Exchange (ETDEWEB)

    Fokkema, D.R.; Sleijpen, G.L.G. [Utrecht Univ. (Netherlands)

    1994-12-31

    In order to solve non-symmetric linear systems of equations, the Conjugate Gradient Squared (CGS) is a well-known and widely used iterative method. In practice the method converges fast, often twice as fast as the Bi-Conjugate Gradient method. This is what you may expect, since CGS uses the square of the BiCG polynomial. However, CGS may suffer from its erratic convergence behavior. The method may diverge or the approximate solution may be inaccurate. BiCGSTAB uses the BiCG polynomial and a product of linear factors in an attempt to smoothen the convergence. In many cases, this has proven to be very effective. Unfortunately, the convergence of BiCGSTAB may stall when a linear factor (nearly) degenerates. BiCGstab({ell}) is designed to overcome this degeneration of linear factors. It generalizes BiCGSTAB and uses both the BiCG polynomial and a product of higher order factors. Still, CGS may converge faster than BiCGSTAB or BiCGstab({ell}). So instead of using a product of linear or higher order factors, it may be worthwhile to look for other polynomials. Since the BiCG polynomial is based on a three term recursion, a natural choice would be a polynomial based on another three term recursion. Possibly, a suitable choice of recursion coefficients would result in method that converges faster or as fast as CGS, but less erratic. It turns out that an algorithm for such a method can easily be formulated. One particular choice for the recursion coefficients leads to CGS. Therefore one could call this algorithm generalized CGS. Another choice for the recursion coefficients leads to BiCGSTAB. It is therefore possible to mix linear factors and some polynomial based on a three term recursion. This way one may get the best of both worlds. The authors will report on their findings.

  10. Electrochemical proton gradient in Micrococcus lysodeikticus cells and membrane vesicles.

    OpenAIRE

    Friedberg, I.; Kaback, H R

    1980-01-01

    Using the distribution of weak acids to measure the pH gradient (delta pH; interior alkaline) and the distribution of the lipophilic cation [3H]tetraphenylphosphonium+ to monitor the membrane potential (delta psi; interior negative), we studied the electrochemical gradient or protons (delta mu- H+) across the membrane of Micrococcus lysodeikticus cells and plasma membrane vesicles. With reduced phenazine methosulfate as electron donor, intact cells exhibited a relatively constant delta mu- H+...

  11. Study on steel matrix composites with (Ti,Al)N gradient PVD coatings

    OpenAIRE

    G. Matula

    2009-01-01

    Purpose: The paper presents investigation results of structure and properties of steel matrix composites (SMC) uncoated and coated with hard (Ti,Al)N gradient coatings with use of physical vapour deposition process.Design/methodology/approach: Powder Metallurgy, PVD, TEM, SEM, XRD, GDOES, Microhardness tests, Scratch test.Findings: Depositing of gradient (Ti,Al)N coatings onto SMC materials meets the requirements connected with hybrid technology of production, joining powder metallurgy and ph...

  12. Adsorption and deposition of anthraquinone-2-carboxylic acid on alumina studied by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Morihide [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)], E-mail: higo@apc.kagoshima-u.ac.jp; Miake, Takeshi; Mitsushio, Masaru; Yoshidome, Toshifumi [Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan); Ozono, Yoshihisa [Center for Instrumental analysis, Kagoshima University, 1-21-40 Korimoto, Kagoshima 890-0065 (Japan)

    2008-04-30

    The adsorption state of anthraquinone-2-carboxylic acid (AQ-2-COOH) deposited from acetone solutions (0.01-1.00 mg/ml) on native oxide surfaces of Al films was characterized by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy. The oxide was prepared on evaporated Al films at room temperature in an oxygen-dc glow discharge. The morphology of the deposited AQ-2-COOH on the oxide surfaces was observed and analyzed by atomic force microscopy. These surface analyses showed that AQ-2-COOH is adsorbed predominantly as a uniform nanometer-scale film of carboxylate anions on the oxide surfaces deposited from solutions with concentrations lower than or equal to 0.02 mg/ml. It was found that AQ-2-COOH is adsorbed as both a uniform film of anions and as micron-sized particles of neutral molecules with heights of a few tens of nanometers when AQ-2-COOH is deposited from solutions with concentrations higher than 0.02 mg/ml. A comparison of the results obtained by these surface analytical techniques clearly shows the features and advantages of these analytical techniques.

  13. Adsorption and deposition of anthraquinone-2-carboxylic acid on alumina studied by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy

    International Nuclear Information System (INIS)

    The adsorption state of anthraquinone-2-carboxylic acid (AQ-2-COOH) deposited from acetone solutions (0.01-1.00 mg/ml) on native oxide surfaces of Al films was characterized by inelastic electron tunneling spectroscopy, infrared reflection absorption spectroscopy, and X-ray photoelectron spectroscopy. The oxide was prepared on evaporated Al films at room temperature in an oxygen-dc glow discharge. The morphology of the deposited AQ-2-COOH on the oxide surfaces was observed and analyzed by atomic force microscopy. These surface analyses showed that AQ-2-COOH is adsorbed predominantly as a uniform nanometer-scale film of carboxylate anions on the oxide surfaces deposited from solutions with concentrations lower than or equal to 0.02 mg/ml. It was found that AQ-2-COOH is adsorbed as both a uniform film of anions and as micron-sized particles of neutral molecules with heights of a few tens of nanometers when AQ-2-COOH is deposited from solutions with concentrations higher than 0.02 mg/ml. A comparison of the results obtained by these surface analytical techniques clearly shows the features and advantages of these analytical techniques

  14. Biogeochemistry of a temperate forest nitrogen gradient

    Science.gov (United States)

    Perakis, Steven S.; Sinkhorn, Emily R.

    2011-01-01

    Wide natural gradients of soil nitrogen (N) can be used to examine fundamental relationships between plant–soil–microbial N cycling and hydrologic N loss, and to test N-saturation theory as a general framework for understanding ecosystem N dynamics. We characterized plant production, N uptake and return in litterfall, soil gross and net N mineralization rates, and hydrologic N losses of nine Douglas-fir (Pseudotsuga menziesii) forests across a wide soil N gradient in the Oregon Coast Range (USA). Surface mineral soil N (0–10 cm) ranged nearly three-fold from 0.29% to 0.78% N, and in contrast to predictions of N-saturation theory, was linearly related to 10-fold variation in net N mineralization, from 8 to 82 kg N·ha−1·yr−1. Net N mineralization was unrelated to soil C:N, soil texture, precipitation, and temperature differences among sites. Net nitrification was negatively related to soil pH, and accounted for −1·yr−1. Aboveground net primary production per unit net N mineralization varied inversely with soil N, suggesting progressive saturation of plant N demands at high soil N. Hydrologic N losses were dominated by dissolved organic N at low-N sites, with increased nitrate loss causing a shift to dominance by nitrate at high-N sites, particularly where net nitrification exceeded plant N demands. With the exception of N mineralization patterns, our results broadly support the application of the N-saturation model developed from studies of anthropogenic N deposition to understand N cycling and saturation of plant and microbial sinks along natural soil N gradients. This convergence of behavior in unpolluted and polluted forest N cycles suggests that where future reductions in deposition to polluted sites do occur, symptoms of N saturation are most likely to persist where soil N content remains elevated.

  15. Liquid droplet movement on horizontal surface with gradient surface energy

    Institute of Scientific and Technical Information of China (English)

    LIAO Qiang; WANG Hong; ZHU Xun; LI Mingwei

    2006-01-01

    A surface with gradient surface energy was fabricated on a silicon wafer by using the chemical vapor deposition (CVD) technology with the dodecyltrichlorosilane (C12H25Cl3Si) vapor which was adsorbed chemically on the surface of the silicon wafer to form a self-assemble monolayer (ASM) and thus a gradient profile of wettability. The microscopic contours of the gradient surface were measured with Seiko SPA400 atom force microscope (AFM). And the surface wettability profile was characterized by the sessile drop method, measuring the contact angle of fine water droplets that lay on the gradient surface, to represent the distribution of the surface energy on the surface. Using a high-speed video imaging system, the motion of water droplet on the horizontal gradient surface was visualized and the transient velocity was measured under ambient condition. The experimental results show that the liquid droplets can be driven to move from hydrophobic side to hydrophilic side on the horizontal gradient surface and the velocity of droplet can reach up to 40 mm/s. In addition, the motion of the water droplet can be generally divided into two stages: an acceleration stage and a deceleration stage. The droplet presents a squirming movement on the surface with a lower peak velocity and a larger extent of deceleration motion. And the static advancing contact angle of the droplet is obviously larger than the dynamic advancing contact angle on the gradient energy surface.

  16. Rigidity of gradient Ricci Solitons

    OpenAIRE

    Petersen, Peter; Wylie, William

    2007-01-01

    We define a gradient Ricci soliton to be rigid if it is a flat bundle $% N\\times_{\\Gamma}\\mathbb{R}^{k}$ where $N$ is Einstein. It is known that not all gradient solitons are rigid. Here we offer several natural conditions on the curvature that characterize rigid gradient solitons. Other related results on rigidity of Ricci solitons are also explained in the last section.

  17. Gradient boosting machines, a tutorial.

    Science.gov (United States)

    Natekin, Alexey; Knoll, Alois

    2013-01-01

    Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods with a strong focus on machine learning aspects of modeling. A theoretical information is complemented with descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. Three practical examples of gradient boosting applications are presented and comprehensively analyzed. PMID:24409142

  18. Gradient Boosting Machines, A Tutorial

    Directory of Open Access Journals (Sweden)

    Alexey eNatekin

    2013-12-01

    Full Text Available Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods. A theoretical information is complemented with many descriptive examples and illustrations which cover all the stages of the gradient boosting model design. Considerations on handling the model complexity are discussed. A set of practical examples of gradient boosting applications are presented and comprehensively analyzed.

  19. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102406 Chen Gang(China University of Geosciences,Beijing 100083,China);Li Fengming Discussion on Geological Characteristics and Genesis of Yuquanshan Graphite Deposit of Xinjiang(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,27(4),2009,p.325-329,4 illus.,4 tables,5 refs.)Key words:graphite deposit,XinjiangYuquanshan graphite deposit of Xinjiang occurs in mica-quartz schist of Xingeer Information which belongs to Xinditate Group of Lower Pt in Kuluketage Block of Tarim paleo-continent,and experiences two mineralizing periods of

  20. Denaturing gradient gel electrophoresis

    International Nuclear Information System (INIS)

    It is worthwhile considering that only some 30 species make up the bulk of the bacterial population in human faeces at any one time based on the classical cultivation-based approach. The situation in the rumen is similar. Thus, it is practical to focus on specific groups of interest within the complex community. These may be the predominant or the most active species, specific physiological groups or readily identifiable (genetic) clusters of phylogenetically related organisms. Several 16S rDNA fingerprinting techniques can be invaluable for selecting and monitoring sequences or phylogenetic groups of interest and are described below. Over the past few decades, considerable attention was focussed on the identification of pure cultures of microbes on the basis of genetic polymorphisms of DNA encoding rRNA such as ribotyping, amplified fragment length polymorphism and randomly amplified polymorphic DNA. However, many of these methods require prior cultivation and are less suitable for use in analysis of complex mixed populations although important in describing cultivated microbial diversity in molecular terms. Much less attention was given to molecular characterization of complex communities. In particular, research into diversity and community structure over time has been revolutionized by the advent of molecular fingerprinting techniques for complex communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations

  1. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2014-01-01

    <正>20140876 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China);Yang Ruidong Study on the Strontium Isotopic Composition of Large Devonian Barite Deposits from Zhenning,Guizhou Province(Geochimica,

  2. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>20122457 Cai Jianshe ( Fujian Institute of Geological Survey and Drawing,Fuzhou 350011,China ) On the Geologic Characteristics and Genesis of the Longtangsi Fluorite Deposit in Pucheng County,Fujian Province ( Geology of Fujian,ISSN1001-3970,CN35-1080 / P,30 ( 4 ), 2011,p.301-306,3illus.,1table,6 refs.,with English abstract ) Key words:fluorspar deposit,Fujian Province

  3. Electric field gradients in metals

    International Nuclear Information System (INIS)

    A review of the recent works on electric field gradient in metals is given. The main emphasis is put on the temperature dependence of the electric field gradient in nonmagnetic metals. Some methods of investigation of this effect using nuclear probes are described. One of them is nuclear accoustic resonance method. (S.B.)

  4. Composition Gradient Hard Coatings by Arc Ion Plating

    Institute of Scientific and Technical Information of China (English)

    CHENJun; LINGuo-qiang; WANGFu-gang

    2004-01-01

    Arc Ion Plating can be used to synthesize multi-component composition gradient hard coatings by adjusting arc currents of metal targets. The present work aims at a comprehensive description of such a technique. The examples of TiAl multi-layer alloy coatings and (Ti,M) N composition-gradient films were taken (M representing Zr, Nb etc.) for the purpose of explaining the working process and evaluating practical effects. The results show that this technique has the advantages of easy manipulation, rapid deposition, and wide composition range.

  5. Assembly processes under severe abiotic filtering: adaptation mechanisms of weed vegetation to the gradient of soil constraints.

    Directory of Open Access Journals (Sweden)

    Nina Nikolic

    Full Text Available Effects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response?Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate.We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils over short distances (field scale.The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.Using annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically

  6. Study of the Structural and Mechanical Properties of Nanocrystalline TiAlSiN Gradient Coatings

    NARCIS (Netherlands)

    Cholakova, T.; Chitanov, V.; Chaliampalias, D.; Kolaklieva, L.; Kakanakov, R.; Bahchedjiev, Ch.; Petkov, N.; Pashinski, Ch.; Vourlias, G.; Vouroutzis, N.; Polychroniadis, E.; Wang, Y.; Meletis, E. I.

    2014-01-01

    A study of the structural and mechanical properties of nanocrystalline TiAlSiN gradient coatings deposited by cathodic arc deposition techniques at 500 degrees C and post-annealed at 525 degrees C is presented. Analysis of the coatings, chemical composition and microstructure revealed that the coati

  7. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>20091594 Bao Yafan(The Third Geologic Survey of Jilin Province,Siping 136000,China);Liu Yanjun Relations between Bashenerxi Granite,West Dongkunlun and Baiganhu Tungsten-Tin Deposit(Jilin Geology,ISSN1001-2427,CN22-1099/P,27(3),2008,p.56-59,67,5 illus.,2 tables,7 refs.,with English abstract)Key words:tungsten ores,tin ores,monzogranite,Kunlun Mountains20091595 Chen Fuwen(Yichang Institute of Geology and Mineral Resources,China Geological Survey,Yichang 443003,China);Dai Pingyun Metallogenetic and Isotopic Chronological Study on the Shenjiaya Gold Deposit in Xuefeng Mountains,Hunan Province(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,82(7),2008,p.906-911,3 illus.,2 tables,30 refs.)Key words:gold ores,HunanThe Shenjiaya gold deposit is a representative one

  8. Combining Step Gradients and Linear Gradients in Density.

    Science.gov (United States)

    Kumar, Ashok A; Walz, Jenna A; Gonidec, Mathieu; Mace, Charles R; Whitesides, George M

    2015-06-16

    Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levitation of diamagnetic objects in a paramagnetic fluid within a magnetic field gradient—can be arranged to provide a near-linear gradient in effective density where the height of a levitating object above the surface of the magnet corresponds to its density; the strength of the gradient in effective density can be tuned by the choice of paramagnetic salt and its concentrations and by the strength and gradient in the magnetic field. Including paramagnetic salts (e.g., MnSO4 or MnCl2) in AMPS, and placing them in a magnetic field gradient, enables their use as media for MagLev. The potential to create large steps in density with AMPS allows separations of objects across a range of densities. The gradients produced by MagLev provide resolution over a continuous range of densities. By combining these approaches, mixtures of objects with large differences in density can be separated and analyzed simultaneously. Using MagLev to add an effective gradient in density also enables tuning the range of densities captured at an interface of an AMPS by simply changing the position of the container in the magnetic field. Further, by creating AMPS in which phases have different concentrations of paramagnetic ions, the phases can provide different resolutions in density. These results suggest that combining steps in density with gradients in density can enable new classes of separations based on density. PMID:25978093

  9. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111705 An Junbo(Team 603,Bureau of Nonferrous Metals Geological Exploration of Jilin Province,Hunchun 133300,China);Xu Renjie Geological Features and Ore Genesis of Baishilazi Scheelite Deposit in Yanbian Area(Jilin Geology,ISSN1001-2427,CN22-1099/P,29(3),2010,p.39-43,2 illus.,2 tables,7 refs.)Key words:tungsten ores,Jilin ProvinceThe Baishilazi scheelite deposit is located in contacting zone between the marble of the Late Palaeozoic Qinglongcun Group and the Hercynian biotite granite.The vein and lenticular major ore body is obviously controlled by NE-extending faults and con

  10. Changes in Sediment Fatty Acid Composition during Passage through the Gut of Deposit Feeding Holothurians: Holothuria atra (Jaeger, 1883) and Holothuria leucospilota (Brandt, 1835).

    Science.gov (United States)

    Mfilinge, Prosper L; Tsuchiya, Makoto

    2016-01-01

    Sea cucumbers Holothuria atra and Holothuria leucospilota play an important role in the bioturbation of sediment in coral reef and rocky intertidal ecosystems. This study investigated changes in sediment fatty acid (FA) composition during gut passage in H. atra and H. leucospilota. The FA composition did not differ significantly between species. Comparison of FA composition in ambient sediment (AS), foregut (FG), midgut (MG), hindgut (HG), and faecal pellets (FPs) indicated that marked changes in FA composition occurred during passage through the gut of H. atra and H. leucospilota. Saturated fatty acids (SAFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), and branched fatty acids (BrFAs) were significantly higher in FG than in AS, suggesting that both species selectively ingested nutrient rich particles. Significant reduction of SAFAs, MUFAs, PUFAs, and BrFAs occurred in MD and HD, with complete elimination of most PUFAs in FPs. A decrease in PUFAs 20:5ω3, 18:4ω3, 22:5ω3, 22:6ω3, 18:2ω6, 18:3ω3, 18:3ω6, odd-numbered BrFAs, and MUFA 18:1ω7 indicated that algal detritus and bacteria were important part of diet. These results have implications for the fate of specific dietary FAs, especially ω3 and ω6, and the contribution holothurian FPs make to the FA composition of coral reef and rocky intertidal ecosystems. PMID:27042355

  11. Changes in Sediment Fatty Acid Composition during Passage through the Gut of Deposit Feeding Holothurians: Holothuria atra (Jaeger, 1883 and Holothuria leucospilota (Brandt, 1835

    Directory of Open Access Journals (Sweden)

    Prosper L. Mfilinge

    2016-01-01

    Full Text Available Sea cucumbers Holothuria atra and Holothuria leucospilota play an important role in the bioturbation of sediment in coral reef and rocky intertidal ecosystems. This study investigated changes in sediment fatty acid (FA composition during gut passage in H. atra and H. leucospilota. The FA composition did not differ significantly between species. Comparison of FA composition in ambient sediment (AS, foregut (FG, midgut (MG, hindgut (HG, and faecal pellets (FPs indicated that marked changes in FA composition occurred during passage through the gut of H. atra and H. leucospilota. Saturated fatty acids (SAFAs, monounsaturated fatty acids (MUFAs, polyunsaturated fatty acids (PUFAs, and branched fatty acids (BrFAs were significantly higher in FG than in AS, suggesting that both species selectively ingested nutrient rich particles. Significant reduction of SAFAs, MUFAs, PUFAs, and BrFAs occurred in MD and HD, with complete elimination of most PUFAs in FPs. A decrease in PUFAs 20:5ω3, 18:4ω3, 22:5ω3, 22:6ω3, 18:2ω6, 18:3ω3, 18:3ω6, odd-numbered BrFAs, and MUFA 18:1ω7 indicated that algal detritus and bacteria were important part of diet. These results have implications for the fate of specific dietary FAs, especially ω3 and ω6, and the contribution holothurian FPs make to the FA composition of coral reef and rocky intertidal ecosystems.

  12. Hydrothermal deposition and the photochromic properties of molybdenum oxide hydrate (MoO{sub 3}⋅(H{sub 2}O){sub 0.69}) films induced by D, L-malic acid

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yi, E-mail: sysy7373@163.com; Xiao, Yilin; Yan, Peng; Yang, Yali; Hu, Fengping; Li, Zhen

    2014-03-05

    Graphical abstract: The molybdenum oxide hydrate (MoO{sub 3}⋅(H{sub 2}O){sub 0.69}) films were synthetized through a hydrothermal route with or without the D, L-malic acid as capping agent. The SEM images indicate that the films obtained without D, L-malic acid show the hexagonal prismatic structures while the films prepared with the capping agent reveal the dandelion-like hierarchical structures, and all the films have double-layer structures. Compared with the films synthetized without the D, L-malic acid, the films prepared with the capping agent show a superior photochromic properties. And the more complete the dandelion-like structures, the better performance the films possess. The best performance appeared when the film was prepared with molar ratio of D, L-malic acid and sodium molybdate at 1:5. The enhanced photochromic performances of the films may be ascribed to the dandelion-like hierarchical structures which can provide large exposed surface and ultimately, increase the amount of the photogenerated electron–hole pairs and the proton diffusion rates. -- Highlights: • Two kinds of films with novel morphologies were obtained with simple hydrothermal process. • Adding D, L-malic acid to the hydrothermal system obviously change the structure of the films. • The film with dandelion-like hierarchical structures showed better photochromic properties. -- Abstract: Two kinds of molybdenum oxide hydrate films were successfully synthesized by a simple hydrothermal deposition method. The X-ray diffraction shows that all the samples can be indexed to hexagonal structure of MoO{sub 3}·(H{sub 2}O){sub 0.69}. Scanning electron microscopy images of the products revealed that hexagonal prismatic structures were revealed on the surface of the sample prepared without capping. While the surface of ones obtained with D, L-malic acid were covered by dandelion-like hierarchical structures, which may result from the effect of hydrogen bonds, and the dandelion

  13. 酸沉降胁迫对不同家系马尾松幼苗耐酸性的影响%Assessment of Acid-Tolerant Parameters of Different Pinus massoniana Families under Acid Deposition Stress

    Institute of Scientific and Technical Information of China (English)

    王水良; 王平; 许建华

    2013-01-01

    The seedlings of 16 elite Masson pine (Pinus massoniana) families,with stable high-yield,including family 35,38,76,78,79,80,88,89,90,114,115,116,117,119,16,147,and 151,were used to explore the effects of precipitation acidity on their acid tolerance.The physiological parameters (biomass,relative plasma membrane permeability,chlorophyll) of the families cultivated in root-boxes outdoor were measured under treatments by spraying simulated acid rain at different pH values (2.5,3.5,4.5 and 5.6).The results showed that the biomass and chlorophyll content decreased with the increase of rain acidity,but the ratios of chlorophyll a/b increased with the increase of rain acidity.In addition,with the rain acidity increased,the relative plasma membrane permeability of the pine seedlings increased,suggesting that the injury of cell membrane was enhanced.These parameters varied with different P.massoniana families.Meanwhile,when rain pH decreased from 5.6 to 4.5,these parameters were slightly decline,but a significant decline was observed from pH 3.5 to 2.5,indicating that these pine families had relatively high productivity under mild acid environment at pH 4.5 to 5.6,and suggesting the tree species,Masson pine,would be suitable for being planted in mild acid soils.

  14. Flame Propagation Through Concentration Gradient

    Institute of Scientific and Technical Information of China (English)

    JunyaIINO; MitsuakiTANABE; 等

    2000-01-01

    The experiment was carried out in homogeneous propane-air mixture and in several concentration gradient of mixture.Igniter is put on the upper side of the combustion chamber,In concentration gradient experiment.ixture was ignited from lean side.An experimental study was conducted in a combustion chamber.The combustion chamber has glass windows for optical measurements at any side.For the measurement of distribution of fuel concentration,infraed absorption method using 3.39μm He-Ne laser was used,and for the observation of proagating flams,Schlieren method was employed.As a measurment result of flame propagation velocity and flammable limit,for a mixture of an identical local equivalence ratio.flame propagation velocity in concentration gradient is faster than that in homogeneous mixture,and rich flammable limit in concentration gradient shows a tendency to be higher than that in homogeneous mixture.

  15. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131565 Cai Lianyou(No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China);Weng Wangfei Geological Characteristics and Genesis Analysis of Guocun Navajoite Deposit in South Anhui Province(Mineral Resources and Geology,

  16. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>20102341 Bao Peisheng(Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China)Further Discussion on the Genesis of the Podiform Chromite Deposits in the Ophiolites-Questioning about the Rock:Melt Interaction Metallogeny(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,28(12),2009,p.1741-1761

  17. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>20131601 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550003,China);Yang Ruidong Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province(Acta Sedimentologica Sinica,ISSN1000-0550,CN62-1038/P,30(3),

  18. METALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    20150904An Fang(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi’an 710069,China);Wang Juli Skarn Mineral Assemblage in Representative Ore Districts of Sayak Copper Orefield,Kazakhstan,and Its Genetic Implications(Mineral Deposits,ISSN0258-7106,CN11-1965/P,33(3),2014,p.521-540,

  19. Long pendulums in gravitational gradients

    Energy Technology Data Exchange (ETDEWEB)

    Suits, B H [Physics Department, Michigan Technological University, Houghton, MI 49931 (United States)

    2006-03-01

    Previous results for long pendulums above a spherical Earth are generalized for arbitrary non-uniform gravitational fields in the limit of small oscillation. As is the case for the previous results, gravitational gradients are multiplied by the length of the string even though the string is assumed massless. The effect is shown to arise from the constraint on the motion imposed by the string. The significance of these results for real gradients is discussed. (letters and comments)

  20. Gradient boosting machines, a tutorial

    OpenAIRE

    Natekin, Alexey; Knoll, Alois

    2013-01-01

    Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods with a strong focus on machine learning aspects of modeling. A theoretical information is complemented with de...

  1. Gradient Boosting Machines, A Tutorial

    OpenAIRE

    Alexey Natekin; Alois Knoll

    2013-01-01

    Gradient boosting machines are a family of powerful machine-learning techniques that have shown considerable success in a wide range of practical applications. They are highly customizable to the particular needs of the application, like being learned with respect to different loss functions. This article gives a tutorial introduction into the methodology of gradient boosting methods. A theoretical information is complemented with many descriptive examples and illustrations which cover all th...

  2. The pressure gradient in the human respiratory tract

    Science.gov (United States)

    Chovancová, Michaela; Elcner, Jakub

    2014-03-01

    Respiratory airways cause resistance to air flow during inhalation and exhalation. The pressure gradient is necessary to transport the air from the mount (or nose) to pulmonary alveoli. The knowledge of pressure gradient (i.e. respiratory airways resistance) is also needed to solve the question of aerosol deposition in the human respiratory tract. The obtained data will be used as boundary conditions for CFD simulations of aerosol transport. Understanding of aerosol transport in the human lungs can help us to determine the health hazard of harmful particles. On the other hand it can be used to set the conditions for transport of medication to the desirable place. This article deals with the description of the mathematical equations defining the pressure gradient and resistance in the bronchial three and describes the geometry used in the calculation.

  3. Preparation of a novel composition-gradient thermosensitive gel

    OpenAIRE

    Tokuyama, Hideaki; Sasaki, Masahiro; Sakohara, Shuji

    2006-01-01

    The feasibility of a novel composition-gradient copolymer gel, in which the composition gradually changes with the distance, was examined. The slab-shaped copolymer gels of a thermosensitive primary component, N-isopropylacrylamide (NIPA) and an ionic secondary component, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) or acrylic acid (AA), were prepared between two substrates of hydrophilic glass and hydrophobic polytetrafluoroethylene (Teflon). In the NIPA-co-AMPS gels, prepared at 40°C...

  4. Properties of the multicomponent and gradient PVD coatings

    OpenAIRE

    L.W. Żukowska; L.A. Dobrzański

    2007-01-01

    Purpose: This paper presents investigation results of the properties of the multicomponent (Ti,Al)N and gradient Ti(C,N) wear resistant coatings, deposited with the PVD process onto the substrate from the cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics.Design/methodology/approach: The methodology includes analysis of the mechanical and functional properties. The Ra parameter was assumed to be the value describing surface roughness. The microhardness tests using the Vickers m...

  5. Effect of Polyelectrolyte and Fatty Acid Soap on the Formation of CaCO3 in the Bulk and the Deposit on Hard Surfaces.

    Science.gov (United States)

    Wang, Hao; Alfredsson, Viveka; Tropsch, Juergen; Ettl, Roland; Nylander, Tommy

    2015-09-30

    The effects of sodium polyacrylate (NaPAA) as well as potassium oleate on the nucleation and calcium carbonate crystal growth on hard surfaces, i.e., stainless steel and silica, have been investigated at different temperatures. The relation between the surface deposition and the corresponding bulk processes has been revealed by combining dynamic light scattering (DLS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and ellipsometry. The aim was to further our understanding of the crystal deposition/growth mechanism and how it can be controlled by the presence of polyelectrolytes (NaPAA) or soap (potassium oleate). The addition of polyelectrolytes (NaPAA) or soap (potassium oleate) decreases the size of CaCO3 particles in bulk solution and affects both crystal structure and morphology in the bulk as well as on hard surfaces. The amount of particles on hard surfaces decreases significantly in the presence of both potassium oleate and NaPAA. This was found to be a consequence of potassium oleate or NaPAA adsorption on the hard surface as well as on the CaCO3 crystal surfaces. Here, the polymer NaPAA exhibited a stronger inhibition effect on the formation and growth of CaCO3 particles than potassium oleate. PMID:26353982

  6. Research on depositing Ni45 alloy on titanium alloy surface by electrospark deposition

    Institute of Scientific and Technical Information of China (English)

    You Tao; Zhang Chunhui; Su Guiqiao; Yan Ping

    2008-01-01

    Taking Ni45 bar as electrode, a strengthened layer of thickness up to 50 pm was built up on BT20 titanium alloy matrix by means of electrospark deposition. Results of phase analysis by using of X-ray diffraction confirmed that the deposition layer was composed mostly of three phases, NiTi, NiTi2layer was up to 910 HV0.05, about 2.7 times as high as that of the matrix. The hardness at the cross-section of the entire deposition layer showed a gradient distribution. The effects of capacitance and deposition time on thickness of deposition layer were also studied, and results showed that with relatively low capacity and short deposition time the deposition layer without cracks can be obtained.

  7. Research on information model for metallogenic specialization of the intermediate-acid magmatic rocks in nanling region: a case of hydrothermal uranium deposit and hydrothermal tungsten and tin deposit

    International Nuclear Information System (INIS)

    Based on geochemistry analysis data of Nanling granite massifs, according to the granite hydrothermal mineralization principle, the article initially proposes the metallogenic specialization factor group target system using GIS geo-information model, establishes metallogenic specialization information model of the uranium and the tungsten mineral intrusions. According to mineralization granite rock element geochemical behavior and magmatic evolution, the paper suggests the measure that metallogenic specialization influence factor will divided into the acidity factor group, the alkalinity factor group, magmatic fractionation factor group, oxidation reduction factor group, rare-earth element factor group, source area factor group, geostructure environment factor group and so on. The paper selects the best factor group meeting the mechanism of mineralization geological and geochemical principles by using kind of statistical analysis model analyses the space and intrinsic relations of some factor. On the basis of the above aspects, it forecasts undistinguished granite massifs by using the model and the criterion. The result accords with geological fact, indicates that metallogenic specialization information model has objectivity and operability, realizes metallogenic specialization quantitative appraisal, and provides a scientific basis further distinguished the ore-bearing granite massifs. (authors)

  8. Continuous gradient temperature Raman spectroscopy of the long chain polyunsaturated fatty acids Docosapentaenoic (DPA, 22:5n-6) and Docosahexaenoic (DHA; 22:6n-3) from -100 to 20° C

    Science.gov (United States)

    The structural, cognitive and visual development of the human brain and retina strictly require long-chain polyunsaturated fatty acids (LC-PUFA). Excluding water, the mammalian brain is about 60% lipid. One of the great unanswered questions with respect to biological science in general is the absolu...

  9. Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid deposition in high-fat diet-induced obese rats

    OpenAIRE

    Eu Chia; Lim Wai; Ton So; Kadir Khalid

    2010-01-01

    Abstract Background The metabolic syndrome, known also as the insulin resistance syndrome, refers to the clustering of several risk factors for atherosclerotic cardiovascular disease. Dyslipidaemia is a hallmark of the syndrome and is associated with a whole body reduction in the activity of lipoprotein lipase (LPL), an enzyme under the regulation of the class of nuclear receptors known as peroxisome proliferator-activated receptor (PPAR). Glycyrrhizic acid (GA), a triterpenoid saponin, is th...

  10. Research Progress on Acid Deposition over China and Effect of Acid Rain on Agricultural Production%中国酸雨及其对农业生产影响的研究进展

    Institute of Scientific and Technical Information of China (English)

    冯颖竹; 陈惠阳; 余土元; 冯茜丹

    2012-01-01

    In order to study the characteristics of acid rain in China and its effect on agricultural production, an overview of 30 years of acid rain over China and its impact on agricultural production were elaborated in this paper. The outcome of characteristics of acid rain in China mainly included the spatial and temporal distribution (geographical distribution) of acidity, and the ion concentration in precipitation. The outcomes of various aspects in the research about effects of acid rain on agricultural production were introduced, which mainly included the seed germination, the growth, the quality and yield of main crops. The main origins of acid rain formation were discussed, and measures to reduce acid rain damage were investigated. Finally, future research was suggested.%为了研究中国酸雨特征及其对农业生产的影响,综述了30多年来有关中国酸雨及其对农业生产影响的研究成果.对中国酸雨特征的研究主要包括中国大气降水酸度分布和离子浓度特征.酸雨对农 业生产影响方面主要包括酸雨对主要农作物种子萌发、生长发育、品质和产量的影响.同时,分析了中国酸雨的成因,探讨了减少酸雨危害的措施,指出了有待研究的科学问题.

  11. Structure And Properties Of PVD Coatings Deposited On Cermets

    Directory of Open Access Journals (Sweden)

    Żukowska L.

    2015-06-01

    Full Text Available The main aim of the research is the investigation of the structure and properties of single-layer and gradient coatings of the type (Ti,AlN and Ti(C,N deposited by physical vapour deposition technology (PVD on the cermets substrate.

  12. Geology and geochemistry of Carlin-type gold deposits in China

    Science.gov (United States)

    Rui-Zhong, H.; Wen-Chao, S.; Xian-Wu, B.; Guang-Zhi, T.; Hofstra, A.H.

    2002-01-01

    mineral assemblages, residence of gold, geochemical signatures, paragenetic sequence, and fluid inclusions are remarkably similar, which indicates that the deposits formed from low salinity, moderately acidic, CO2 and H2S-rich in the crust similar processes at relatively shallow levels in the crust (water evolved to become ore fluids through interactions with sedimentary rocks, although contributions of volatiles or metals from deeper levels are present in some deposits in Nevada. In both countries, the deposits appear to have formed in an area of high paleothermal gradients after a change in stress regime during the later phases of orogenic activity.

  13. 光亮剂对酸性中磷化学镀镍层性能的影响%Effect of brightening agent on properties of medium-phosphorus nickel coating deposited by acidic electroless plating

    Institute of Scientific and Technical Information of China (English)

    杨倩韵; 郑文芝; 张晓明; 鹿轩; 林继月; 陈姚; 于欣伟

    2016-01-01

    The effects of four kinds of brightening agents, i.e. 3-N,N-diethylamino-1-propyne formate (DEP), copper sulfate, composite brightener RS, and sodium saccharin on properties of the medium-phosphorus Ni-P alloy coating deposited from an acidic electroless nickel plating bath were studied by polarization curve measurement, scanning electron microscopy (SEM), neutral salt spray (NSS) test, and other methods. The results showed that the coating obtained with copper sulfate as brightening agent has the highest brightness and a mirror-like surface with an average roughness (Ra) of 0.78μm, but the worst corrosion resistance. The fastest deposition rate was obtained as 21.56μm/h when using sodium saccharin as a brightening agent. The coating deposited by adding the RS intermediate to plating bath shows the best corrosion resistance and a relative good brightness.%采用极化曲线、扫描电子显微镜(SEM)、中性盐雾(NSS)试验等方法,研究了酸性中磷化学镀镍液中N,N?二乙基丙炔胺甲酸盐(DEP)、硫酸铜、复配光亮剂RS和糖精钠4种光亮剂对镀层性能的影响.结果表明,以硫酸铜作为光亮剂所获得的镀层光亮度最高,镀层表面粗糙度(Ra)平均值达0.78μm且呈镜面状态,但镀层耐蚀性最差;用糖精钠作光亮剂时镀速最快,达21.56μm/h;而加入中间体RS的镀层耐蚀性最好,且光亮度较好.

  14. The influence of ALN-Al gradient material gradient index on ballistic performance

    International Nuclear Information System (INIS)

    Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.

  15. Gradient expansion for anisotropic hydrodynamics

    CERN Document Server

    Florkowski, Wojciech; Spaliński, Michał

    2016-01-01

    We compute the gradient expansion for anisotropic hydrodynamics. The results are compared with the corresponding expansion of the underlying kinetic-theory model with the collision term treated in the relaxation time approximation. We find that a recent formulation of anisotropic hydrodynamics based on an anisotropic matching principle yields the first three terms of the gradient expansion in agreement with those obtained for the kinetic theory. This gives further support for this particular hydrodynamic model as a good approximation of the kinetic-theory approach. We further find that the gradient expansion of anisotropic hydrodynamics is an asymptotic series, and the singularities of the analytic continuation of its Borel transform indicate the presence of non-hydrodynamic modes.

  16. Gradient Domain Guided Image Filtering.

    Science.gov (United States)

    Kou, Fei; Chen, Weihai; Wen, Changyun; Li, Zhengguo

    2015-11-01

    Guided image filter (GIF) is a well-known local filter for its edge-preserving property and low computational complexity. Unfortunately, the GIF may suffer from halo artifacts, because the local linear model used in the GIF cannot represent the image well near some edges. In this paper, a gradient domain GIF is proposed by incorporating an explicit first-order edge-aware constraint. The edge-aware constraint makes edges be preserved better. To illustrate the efficiency of the proposed filter, the proposed gradient domain GIF is applied for single-image detail enhancement, tone mapping of high dynamic range images and image saliency detection. Both theoretical analysis and experimental results prove that the proposed gradient domain GIF can produce better resultant images, especially near the edges, where halos appear in the original GIF. PMID:26285153

  17. Selective deposition of dietary α-Lipoic acid in mitochondrial fraction and its synergistic effect with α-Tocoperhol acetate on broiler meat oxidative stability

    OpenAIRE

    Parveen, Rashida; Asghar, Ali; Anjum, Faqir M.; Khan, Muhammad I; Arshad, Muhammad Sajid; Yasmeen, Ammara

    2013-01-01

    The use of bioactive antioxidants in feed of broiler to mitigate reactive oxygen species (ROS) in biological systems is one of promising nutritional strategies. The aim of present study was to alleviate ROS production in mitochondrial fraction (MF) of meat by supplemented dietary antioxidant in feed of broiler. For this purpose, mitochondria specific antioxidant: α-lipoic acid (25 mg, 75 mg and 150 mg) with or without combination of α-tocopherol acetate (200 mg) used in normal and palm olein ...

  18. Reducing Water Vapor Permeability of Poly(lactic acid Film and Bottle through Layer-by-Layer Deposition of Green-Processed Cellulose Nanocrystals and Chitosan

    Directory of Open Access Journals (Sweden)

    Katalin Halász

    2015-01-01

    Full Text Available Layer-by-layer electrostatic self-assembly technique was applied to improve the barrier properties of poly(lactic acid (PLA films and bottles. The LbL process was carried out by the alternate adsorption of chitosan (CH (polycation and cellulose nanocrystals (CNC produced via ultrasonic treatment. Four bilayers (on each side of chitosan and cellulose nanocrystals caused 29 and 26% improvement in barrier properties in case of films and bottles, respectively. According to the results the LbL process with CH and CNC offered a transparent “green” barrier coating on PLA substrates.

  19. Thermal Gradient Behavior of TBCs Subjected to a Laser Gradient Test Rig: Simulating an Air-to-Air Combat Flight

    Science.gov (United States)

    Lima, Rogerio S.; Marple, Basil R.; Marcoux, P.

    2016-01-01

    A computer-controlled laser test rig (using a CO2 laser) offers an interesting alternative to traditional flame-based thermal gradient rigs in evaluating thermal barrier coatings (TBCs). The temperature gradient between the top and back surfaces of a TBC system can be controlled based on the laser power and a forced air back-face cooling system, enabling the temperature history of complete aircraft missions to be simulated. An air plasma spray-deposited TBC was tested and, based on experimental data available in the literature, the temperature gradients across the TBC system (ZrO2-Y2O3 YSZ top coat/CoNiCrAlY bond coat/Inconel 625 substrate) and their respective frequencies during air-to-air combat missions of fighter jets were replicated. The missions included (i) idle/taxi on the runway, (ii) take-off and climbing, (iii) cruise trajectory to rendezvous zone, (iv) air-to-air combat maneuvering, (v) cruise trajectory back to runway, and (vi) idle/taxi after landing. The results show that the TBC thermal gradient experimental data in turbine engines can be replicated in the laser gradient rig, leading to an important tool to better engineer TBCs.

  20. Bond Growth under Temperature Gradient.

    Directory of Open Access Journals (Sweden)

    P.K. Satyawali

    1999-12-01

    Full Text Available Grain and bond growth for dry snow are determined by the distribution of temperature andtemperature gradient in the snow matrix. From the standpoint of particle approach and based oncubic packing structure, a bond growth model has been developed for TG metamorphism. The paper.highlights the importance of bond formation and its effect on snow viscosity and finally on the rateof settlement. This is very important for developing a numerical snow pack model if microstructureis considered to be a basic parameter. A few experiments have been carried out to validate bond formation under temperature gradient.

  1. Quasi-two-dimensional Turing patterns in an imposed gradient

    Science.gov (United States)

    Lengyel, István; Kádár, Sándor; Epstein, Irving R.

    1992-11-01

    In experiments on quasi-two-dimensional Turing structures, patterns form perpendicular to a concentration gradient imposed by the boundary conditions. Using linear stability analysis, with the ClO2-I2-MA (malonic acid) reaction as an example, we obtain conditions on the position along the gradient direction and possible three dimensionality of the structures. Experiments on the effects of MA and starch concentrations on the position of the structures support the theory. Simulations taking into account the starch indicator yield Turing patterns even with equal diffusion coefficients for the activator and inhibitor species.

  2. Preparation and characterization of chemical gradient surfaces and their application for the study of cellular interaction phenomena

    NARCIS (Netherlands)

    Ruardy, TG; Schakenraad, JM; vanderMei, HC; Busscher, HJ

    1997-01-01

    Chemical gradient surfaces are surfaces with a gradually changing chemistry along their length which is responsible for a position bound variation in physical properties, most notably, the wettability. In this review, methods to prepare (palladium deposition, diffusion technique, density gradient me

  3. Towards Sustainable Aquafeeds: Complete Substitution of Fish Oil with Marine Microalga Schizochytrium sp. Improves Growth and Fatty Acid Deposition in Juvenile Nile Tilapia (Oreochromis niloticus)

    Science.gov (United States)

    Sarker, Pallab K.; Kapuscinski, Anne R.; Lanois, Alison J.; Livesey, Erin D.; Bernhard, Katie P.; Coley, Mariah L.

    2016-01-01

    We conducted a 84-day nutritional feeding experiment with dried whole cells of DHA-rich marine microalga Schizochytrium sp. (Sc) to determine the optimum level of fish-oil substitution (partial or complete) for maximum growth of Nile tilapia. When we fully replaced fish oil with Schizochytrium (Sc100 diet), we found significantly higher weight gain and protein efficiency ratio (PER), and lower (improved) feed conversion ratio (FCR) and feed intake compared to a control diet containing fish oil (Sc0); and no significant change in SGR and survival rate among all diets. The Sc100 diet had the highest contents of 22:6n3 DHA, led to the highest DHA content in fillets, and consequently led to the highest DHA:EPA ratios in tilapia fillets. Schizochytrium sp. is a high quality candidate for complete substitution of fish oil in juvenile Nile tilapia feeds, providing an innovative means to formulate and optimize the composition of tilapia juvenile feed while simultaneously raising feed efficiency of tilapia aquaculture and to further develop environmentally and socially sustainable aquafeeds. Results show that replacing fish oil with DHA-rich marine Sc improves the deposition of n3 LC PUFA levels in tilapia fillet. These results support further studies to lower Schizochytrium production costs and to combine different marine microalgae to replace fish oil and fishmeal into aquafeeds. PMID:27258552

  4. Developing soil treatment design criteria for large upland and lowland areas in southwest Montana impacted by metalliferous and acidic smelter emissions and fluvial tailings deposition

    Energy Technology Data Exchange (ETDEWEB)

    Emilsson, G. [CDM, Helena, MT (United States); Coleman, C. [United States Environmental Protection Agency, Helena, MT (United States)

    2006-07-01

    As a result of nearly 100 years of deposition of smelter emissions and fluvially transported mine wastes from the operation of the Anaconda copper smelter, over 10,000 acres of upland and lowland areas in the southern Deer Lodge valley in southwestern Montana are barren or sparsely vegetated. The smelter ceased operations in 1980 and is scheduled for remediation under the Anaconda Regional Water, Waste and Soils Operable Unit of the Anaconda Smelter National Priorities List (NPL) Site. This paper presented site-specific design criteria for the remediation of the affected soils through the re-establishment of vegetation and discussed the basis of design that was used to develop them. It also presented investigative studies that meet the nine criteria specified by the National Contingency Plan in designing criteria for the treatment of impacted soils having low pH and containing elevated metals concentrations. This included plant growth studies conducted in a greenhouse environment to investigate varying application rates of different types of soil amendments; demonstration plots performed on site to test in the field potential treatments that showed promise in the greenhouse; and extensive data collection in the uplands to characterize the extent of contamination, as well as identify existing soil properties that can be used to optimize the remedial design. Last, the paper presented design criteria pertaining to pH, lime amendments, and organic matter additions, including metals phytotoxicity design considerations. 18 refs., 2 tabs., 2 figs.

  5. Towards Sustainable Aquafeeds: Complete Substitution of Fish Oil with Marine Microalga Schizochytrium sp. Improves Growth and Fatty Acid Deposition in Juvenile Nile Tilapia (Oreochromis niloticus).

    Science.gov (United States)

    Sarker, Pallab K; Kapuscinski, Anne R; Lanois, Alison J; Livesey, Erin D; Bernhard, Katie P; Coley, Mariah L

    2016-01-01

    We conducted a 84-day nutritional feeding experiment with dried whole cells of DHA-rich marine microalga Schizochytrium sp. (Sc) to determine the optimum level of fish-oil substitution (partial or complete) for maximum growth of Nile tilapia. When we fully replaced fish oil with Schizochytrium (Sc100 diet), we found significantly higher weight gain and protein efficiency ratio (PER), and lower (improved) feed conversion ratio (FCR) and feed intake compared to a control diet containing fish oil (Sc0); and no significant change in SGR and survival rate among all diets. The Sc100 diet had the highest contents of 22:6n3 DHA, led to the highest DHA content in fillets, and consequently led to the highest DHA:EPA ratios in tilapia fillets. Schizochytrium sp. is a high quality candidate for complete substitution of fish oil in juvenile Nile tilapia feeds, providing an innovative means to formulate and optimize the composition of tilapia juvenile feed while simultaneously raising feed efficiency of tilapia aquaculture and to further develop environmentally and socially sustainable aquafeeds. Results show that replacing fish oil with DHA-rich marine Sc improves the deposition of n3 LC PUFA levels in tilapia fillet. These results support further studies to lower Schizochytrium production costs and to combine different marine microalgae to replace fish oil and fishmeal into aquafeeds. PMID:27258552

  6. MILLIMETER-SCALE GENETIC GRADIENTS AND COMMUNITY-LEVEL MOLECULAR CONVERGENCE IN A HYPERSALINE MICROBIAL MAT

    Energy Technology Data Exchange (ETDEWEB)

    Fenner, Marsha W; Kunin, Victor; Raes, Jeroen; Harris, J. Kirk; Spear, John R.; Walker, Jeffrey J.; Ivanova, Natalia; Mering, Christian von; Bebout, Brad M.; Pace, Norman R.; Bork, Peer; Hugenholtz, Philip

    2008-04-30

    To investigate the extent of genetic stratification in structured microbial communities, we compared the metagenomes of 10 successive layers of a phylogenetically complex hypersaline mat from Guerrero Negro, Mexico. We found pronounced millimeter-scale genetic gradients that are consistent with the physicochemical profile of the mat. Despite these gradients, all layers displayed near identical and acid-shifted isoelectric point profiles due to a molecular convergence of amino acid usage indicating that hypersalinity enforces an overriding selective pressure on the mat community.

  7. On gradient Ricci solitons with Symmetry

    OpenAIRE

    Petersen, Peter; Wylie, William

    2007-01-01

    We study gradient Ricci solitons with maximal symmetry. First we show that there are no non-trivial homogeneous gradient Ricci solitons. Thus the most symmetry one can expect is an isometric cohomogeneity one group action. Many examples of cohomogeneity one gradient solitons have been constructed. However, we apply the main result in our paper "Rigidity of gradient Ricci solitons" to show that there are no noncompact cohomogeneity one shrinking gradient solitons with nonnegative curvature.

  8. The geomagnetic field gradient tensor

    DEFF Research Database (Denmark)

    Kotsiaros, Stavros; Olsen, Nils

    2012-01-01

    We develop the general mathematical basis for space magnetic gradiometry in spherical coordinates. The magnetic gradient tensor is a second rank tensor consisting of 3 × 3 = 9 spatial derivatives. Since the geomagnetic field vector B is always solenoidal (∇ · B = 0) there are only eight independe...... of the small-scale structure of the Earth’s lithospheric field....

  9. 梯度温度法提高L-赖氨酸发酵水平的研究%Study on the conditions of L-lysine acid production with gradient temperature fermentation

    Institute of Scientific and Technical Information of China (English)

    廉少杰; 张伟国

    2012-01-01

    对黄色短杆菌(Brevibacterium flavum)XQ90发酵生产赖氨酸的条件进行了研究。结果表明:两阶段温度控制策略(0~18h31℃,18h~结束34℃)更有利于提高产量和发酵强度;在控温的基础上发酵周期缩短至60h;同时通过连续流加葡萄糖和硫酸铵确定了最佳残糖维持浓度5~10g/L和最佳氨氮浓度1.0~2.0g/L;在最优条件下,赖氨酸盐酸盐的产量从111g/L提高到151g/L,糖酸转化率达50.2%。%Abstract.Fermentation conditions of Brevibacterium flavum XQ90 for lysine acid production were studied. It was found that the two-stage temperature strategy was better for fermentation (0-18h 31℃, 18h-end 34℃), and fermentation time was decreased to 60h in the new process. At the same time the optimal residual sugar concentration was 5-10g/L, and ammomia nitrogen was 1.0-2.0g/L.As a result, under the optimum fermentation conditions,Lys. HCI productivity was enhanced from 111g/L to 151 g/L, and conversation rate from glucose to lysine acid was 50.2%.

  10. Covalently immobilized gelatin gradients within three-dimensional porous scaffolds

    Institute of Scientific and Technical Information of China (English)

    WU JinDan; TAN HuaPing; LI LinHui; GAO ChangYou

    2009-01-01

    A stable gelatin gradient providing continuous increment of signaling for cell adhesion and proliferation was fabricated within 3D poly(L-lactic acid) (PLLA) scaffolds. The porous PLLA scaffold fabricated by NaCI particle leaching was vertically fixed on a glass vial. 1,6-Hexanediamine/propanol solution was continuously injected into the vial by a micropump to aminolyze the PLLA scaffold. As a result of reaction time difference,the introduced-NH2 groups increased continuously along with the longitude of the PLLA scaffold in the z-direction. After covalent immobilization of gelatin by glutaraldehyde coupling,the gelatin gradient scaffold was thus obtained. In vitro chondrocyte culture showed that the cells had higher viability and more extending morphology in the gelatin gradient scaffold than that in the uniform gelatin control.

  11. Microfabricated refractive index gradient based detector for reversed-phase liquid chromatography with mobile phase gradient elution.

    Science.gov (United States)

    McBrady, Adam D; Synovec, Robert E

    2006-02-10

    Typical refractive index (RI) detectors for liquid chromatography (LC) are not well suited to application with mobile phase gradient elution, due to the difficulty in correcting for the detected baseline shift during the gradient. We report a sensitive, highly reproducible, microfabricated refractive index gradient (micro-RIG) detector that performs well with mobile phase gradient elution LC. Since the micro-RIG signal remains on-scale throughout the mobile phase gradient, one can apply a baseline correction procedure. We demonstrate that by collecting two mobile phase gradient blanks and subtracting one of them from the other, a reproducible, flat baseline is achieved. Therefore, subtracting a blank from a separation provides a baseline corrected chromatogram with reasonably high signal-to-noise ratio for eluting analytes. The micro-RIG detector uses a collimated diode laser beam to optically probe a RIG formed perpendicular to the laminar flow direction within a microfabricated borosilicate glass chip. The chip-based design of the detector is suitable for either traditional bench-top or LC-on-a-chip technologies. We report reversed phase high performance liquid chromatography (RP-HPLC) separations of proteins and polymers, over mobile phase gradient conditions of 67% A:33% B to 3% A:97% B by volume, where A is 96% methanol:3.9% water:0.1% trifluoroacetic acid (TFA), and B is 3.9% methanol:96% water:0.1% TFA. The separations were performed on a Jupiter 5 mu C4 300 A 150 mm x 1.0 mm Phenomenex column at a flow rate of 20 microl/min. Viscosity changes during the mobile phase gradient separation are found to shift the on-chip merge position of the detected concentration gradient (i.e., RIG), in a reproducible fashion. However, this viscosity effect makes detection sensitivity vary throughout the mobile phase gradient, due to moving the optimized position of the probe beam in relation to the analyte concentration gradient being probed. None-the-less, consistent limits

  12. NONMETALS DEPOSITS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111761 Chen Hua(115 Geological Party,Guizhou Bureau of Geology and Mineral Exploration & Development,Guiyang 551400,China);Deng Chao Analysis on the Metallogenic Environment of Maochang Bauxite in Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(3),2010,p.198-201,2 illus.,1 table,8 refs.)Key words:bauxite deposit,Guizhou Province By long time physical and chemical process,the carbonate rock after Central Guizhou uplidft,becomes red clay,after further weathering,the red clay decomposed into the oxide,hydroxide of Al and Fe,in the dissolution hole and depression,it concentrates primary fragmentary tight and earthy karst bauxite ore.Because the variation of landform,it decomposes and cracks again,affords the material source

  13. Investigation of hard gradient PVD (Ti,Al,SiN coating

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: Investigation of gradient coating of (Ti,Al,SiN deposited on the Al2O3+SiC(woxide ceramics substrate by cathodic arc evaporation CAE-PVD method.Design/methodology/approach: Structure of substrate and coating was investigated with use of scanning electron microscopy (SEM. The X-Ray Photoelectron Spectrometry (XPS examination was carried out for proving the gradient character of the (Ti,Al,SiN coating. The investigation includes also microhardness and roughness tests of the deposited coating and used substrate; The Ra surface roughness parameter measurements were made on confocal microscope.Findings: Gradient structure and main properties of the investigated materials were introduced. It has been stated, that properties of the oxide tool ceramic with gradient (Ti,Al,SiN coating increase in comparison with uncoated material.Practical implications: Depositing the wear resistant gradient coating onto the Al2O3+SiC(woxide tool ceramic results in a significant increase of the surface layer microhardness, contributing most probably in this way in machining to the decrease of the wear intensity of cutting tools’ flanks made from the Al2O3+SiC(woxide tool ceramic.Originality/value: Functionally gradient coating form is a new class of structures in which the microstructure and properties vary gradually from the surface to the interior of the material.

  14. Impacts of atmospheric pollution on the plant communities of British acid grasslands

    Energy Technology Data Exchange (ETDEWEB)

    Payne, Richard J., E-mail: r.payne@mmu.ac.uk [School of Science and the Environment, Manchester Metropolitan University, Chester St., Manchester M1 5GD (United Kingdom); Geography, School of Environment and Development, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Stevens, Carly J. [Faculty of Science, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Lancaster Environment Centre, Lancaster University, Bailrigg, Lancaster LA1 4YQ (United Kingdom); Dise, Nancy B. [School of Science and the Environment, Manchester Metropolitan University, Chester St., Manchester M1 5GD (United Kingdom); Gowing, David J. [Faculty of Science, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Pilkington, Michael G.; Phoenix, Gareth K. [Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Sheffield S10 2TN (United Kingdom); Emmett, Bridget A. [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Ashmore, Michael R. [Environment Department, University of York, Heslington, York YO10 5DD (United Kingdom)

    2011-10-15

    Air pollutants are recognised as important agents of ecosystem change but few studies consider the effects of multiple pollutants and their interactions. Here we use ordination, constrained cluster analysis and indicator value analyses to identify potential environmental controls on species composition, ecological groupings and indicator species in a gradient study of UK acid grasslands. The community composition of these grasslands is related to climate, grazing, ozone exposure and nitrogen deposition, with evidence for an interaction between the ecological impacts of base cation and nitrogen deposition. Ozone is a key agent in species compositional change but is not associated with a reduction in species richness or diversity indices, showing the subtly different drivers on these two aspects of ecosystem degradation. Our results demonstrate the effects of multiple interacting pollutants, which may collectively have a greater impact than any individual agent. - Highlights: > Ozone exposure, N and base cation deposition modify UK acid grassland composition. > Ozone influences community composition without reducing species richness. > Nitrogen and base cation deposition have interacting impacts. > Distinct species responses to pollutants suggest potential for bioindication. - Ozone exposure and nitrogen deposition have distinct but additive impacts on the plant communities of British acid grasslands.

  15. The pyrolysis of YBa2Cu3O7-δ thin films produced by metal-organic deposition using trifluoroacetic acid-based precursors

    International Nuclear Information System (INIS)

    To assist with the optimization of the TFA-MOD process for YBa2Cu3O7-δ coated conductor development, this work examines the pyrolysis stage - in which organic constituents are burned off - on both single crystal as well as buffered nickel substrates. Samples were dip-coated into precursor solutions prepared using metal acetates as well as YBa2Cu3O7-δ powder dissolved in trifluoroacetic acid and placed in a flowing gas furnace with a humid O2 atmosphere. While firing, individual samples were quenched at various temperatures, effectively freezing the pyrolysis development. These samples were then analyzed for phase formation using grazing incidence X-ray diffraction; surface morphology using AFM; decomposition reactions using TGA, DTA, and exhaust gas characterization; and stoichiometry using EDX. Additionally, cross-sectional cuts were made in the pyrolyzed layers with a FIB, facilitating a detailed discussion of the layer morphology. Results indicate that significant layer shrinkage occurs between 200 and 250 C and reveal a large surface tension. BaF2 crystallizes above 270 C while CuO forms above 200 C. FIB results suggest that HF gas evolves above 200 C but is trapped within the layer until 270 C. (orig.)

  16. Analysis of the Clean Air Act Amendments of 1990: A forecast of the electric utility industry response to Title IV, Acid Deposition Control

    International Nuclear Information System (INIS)

    The Clean Air Act Amendments of 1990 incorporate, for the first time, provisions aimed specifically at the control of acid rain. These provisions restrict emissions of sulfur dioxide (SO2) and oxides of nitrogen (NOx) from electric power generating stations. The restrictions on SO2 take the form of an overall cap on the aggregate emissions from major generating plants, allowing substantial flexibility in the industry's response to those restrictions. This report discusses one response scenario through the year 2030 that was examined through a simulation of the utility industry based on assumptions consistent with characterizations used in the National Energy Strategy reference case. It also makes projections of emissions that would result from the use of existing and new capacity and of the associated additional costs of meeting demand subject to the emission limitations imposed by the Clean Air Act. Fuel-use effects, including coal-market shifts, consistent with the response scenario are also described. These results, while dependent on specific assumptions for this scenario, provide insight into the general character of the likely utility industry response to Title IV

  17. Analysis of the Clean Air Act Amendments of 1990: A forecast of the electric utility industry response to Title IV, Acid Deposition Control

    Energy Technology Data Exchange (ETDEWEB)

    Molburg, J.C.; Fox, J.A.; Pandola, G.; Cilek, C.M.

    1991-10-01

    The Clean Air Act Amendments of 1990 incorporate, for the first time, provisions aimed specifically at the control of acid rain. These provisions restrict emissions of sulfur dioxide (SO{sub 2}) and oxides of nitrogen (NO{sub x}) from electric power generating stations. The restrictions on SO{sub 2} take the form of an overall cap on the aggregate emissions from major generating plants, allowing substantial flexibility in the industry`s response to those restrictions. This report discusses one response scenario through the year 2030 that was examined through a simulation of the utility industry based on assumptions consistent with characterizations used in the National Energy Strategy reference case. It also makes projections of emissions that would result from the use of existing and new capacity and of the associated additional costs of meeting demand subject to the emission limitations imposed by the Clean Air Act. Fuel-use effects, including coal-market shifts, consistent with the response scenario are also described. These results, while dependent on specific assumptions for this scenario, provide insight into the general character of the likely utility industry response to Title IV.

  18. Analysis of the Clean Air Act Amendments of 1990: A forecast of the electric utility industry response to Title IV, Acid Deposition Control

    Energy Technology Data Exchange (ETDEWEB)

    Molburg, J.C.; Fox, J.A.; Pandola, G.; Cilek, C.M.

    1991-10-01

    The Clean Air Act Amendments of 1990 incorporate, for the first time, provisions aimed specifically at the control of acid rain. These provisions restrict emissions of sulfur dioxide (SO[sub 2]) and oxides of nitrogen (NO[sub x]) from electric power generating stations. The restrictions on SO[sub 2] take the form of an overall cap on the aggregate emissions from major generating plants, allowing substantial flexibility in the industry's response to those restrictions. This report discusses one response scenario through the year 2030 that was examined through a simulation of the utility industry based on assumptions consistent with characterizations used in the National Energy Strategy reference case. It also makes projections of emissions that would result from the use of existing and new capacity and of the associated additional costs of meeting demand subject to the emission limitations imposed by the Clean Air Act. Fuel-use effects, including coal-market shifts, consistent with the response scenario are also described. These results, while dependent on specific assumptions for this scenario, provide insight into the general character of the likely utility industry response to Title IV.

  19. Electro-spark deposition technology

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.N. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-12-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated critical to the life and economy of the advanced fossil energy systems as the higher temperatures and corrosive environments exceed the limits of known structural materials to accommodate the service conditions. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. A new development is the demonstration of advanced aluminide-based ESD coatings for erosion and wear applications. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that yields an order of magnitude increase in deposition rates and achievable coating thicknesses. Achieving this regime has required the development of advanced ESD electronic capabilities. Development is now focused on further improvements in deposition rates, system reliability when operating at process extremes, and economic competitiveness.

  20. Study of the Chemical Characteristics of Dry Deposition in Typical Acid Rain Areas of China%中国典型酸雨区大气干沉降化学特征研究

    Institute of Scientific and Technical Information of China (English)

    向仁军; 柴立元; 曾光明; 漆燕; 肖劲松; 赵大为

    2011-01-01

    以湖南蔡家塘、贵州雷公山和重庆铁山坪3个小流域长年大气干沉降的监测数据为基础,对三地大气和气溶胶的化学成分的分布特征进行了分析研究.结果表明:三地大气干沉降中主要的酸性物质均为SO2,SO42-,NO2;主要的碱性物质均为NH+4,Ca2+,K+,NH3.SO2的干沉降跟当地S的来源有密切的关系,且具有季节性变化.三地的NH3+NH4+浓度均大于HNO3+NO3-浓度.NO2,NH3的年平均浓度大小均为铁山坪>蔡家塘>雷公山.蔡家塘、雷公山、铁山坪铵态氮年平均浓度在气相和固相中的比率均小于1,蔡家塘硝态氮年平均浓度在气相和固相中的比率接近1;雷公山年硝态氮平均浓度在气相和固相中的比率大于1;铁山坪硝态氮年平均浓度在气相和固相中的比率小于1.%To study the chemical composition characteristics of dry deposition is very important to the understanding of their influence on forest ecosystem. They are the key factors to grasp the formation, transportation and deposition mechanisms of the acidic matters in the air and the aerosol. This paper studied the chemical composition characteristics of air and aerosol based on the monitor data of three typical acidic catchments, including Cai Jia Tang (CJT) in Hunan, Lei Gong Shan (LGS) in Guizhou and Tie Shan Ping (TSP) in Chongqing. The research results have indicated that the dominant acidic materials are SO2, SO4- and NO2, and the dominant basic ones are NHL+ ,Ca2+ ,K+ and NH3. The dry deposition ratio of SO2 has a close relationship with the local sources of sulfur (S) and has seasonal variations as well. The mean seasonal concentration of (NH3 +NH4+ )-N is higher than ( HNO3 +NO3- )-N in all of the three areas. The order of annual mean concentration of NO2-N and NH3-N in the three sections are TSP>CJT>LGS. Furthermore, the gas/particle ratio for the ammonia compounds is less than 1: 1 in the three areas, and that for the nitrogen compounds is close to 1 : 1

  1. Sintered composite gradient tool materials

    OpenAIRE

    J. Mikuła; G. Matula; K. Gołombek; L.A. Dobrzański

    2008-01-01

    Purpose: Development of a new generation of the composite gradient tool materials with the core sintered withthe matrix obtained using the powder metallurgy of the chemical composition corresponding to the HS6-5-2 highspeedsteel reinforced with the WC and TiC type hard carbide phases with the growing portions of these phases inthe outward direction from the core to the surface.Design/methodology/approach: Powder Metallurgy, SEM, X-Ray Microanalysis.Findings: Powder metallurgy processes were u...

  2. Smooth Optimization with Approximate Gradient

    OpenAIRE

    d'Aspremont, Alexandre

    2005-01-01

    We show that the optimal complexity of Nesterov's smooth first-order optimization algorithm is preserved when the gradient is only computed up to a small, uniformly bounded error. In applications of this method to semidefinite programs, this means in some instances computing only a few leading eigenvalues of the current iterate instead of a full matrix exponential, which significantly reduces the method's computational cost. This also allows sparse problems to be solved efficiently using spar...

  3. Multilayer coating for high gradients

    CERN Document Server

    Kubo, Takayuki

    2016-01-01

    The multilayer coating for high gradients is reviewed. Not only the S-I-S structure, but also the S-S bilayer structure are also treated. This is an incomplete manuscript of an invited article which will be submitted to a journal. I have uploaded this version in order to help the understanding on my talk at the TESLA Technology Collaboration meeting at Saclay, France.

  4. Modelling deposition and air concentration of reduced nitrogen in Poland and sensitivity to variability in annual meteorology.

    Science.gov (United States)

    Kryza, Maciej; Dore, Anthony J; Błaś, Marek; Sobik, Mieczysław

    2011-04-01

    The relative contribution of reduced nitrogen to acid and eutrophic deposition in Europe has increased recently as a result of European policies which have been successful in reducing SO(2) and NO(x) emissions but have had smaller impacts on ammonia (NH(3)) emissions. In this paper the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model was used to calculate the spatial patterns of annual average ammonia and ammonium (NH(4)(+)) air concentrations and reduced nitrogen (NH(x)) dry and wet deposition with a 5 km × 5 km grid for years 2002-2005. The modelled air concentrations of NH(3) and dry deposition of NH(x) show similar spatial patterns for all years considered. The largest year to year changes were found for wet deposition, which vary considerably with precipitation amount. The FRAME modelled air concentrations and wet deposition are in reasonable agreement with available measurements (Pearson's correlation coefficients above 0.6 for years 2002-2005), and with spatial patterns of concentrations and deposition of NH(x) reported with the EMEP results, but show larger spatial gradients. The error statistics show that the FRAME model results are in better agreement with measurements if compared with EMEP estimates. The differences in deposition budgets calculated with FRAME and EMEP do not exceed 17% for wet and 6% for dry deposition, with FRAME estimates higher than for EMEP wet deposition for modelled period and lower or equal for dry deposition. The FRAME estimates of wet deposition budget are lower than the measurement-based values reported by the Chief Inspectorate of Environmental Protection of Poland, with the differences by approximately 3%. Up to 93% of dry and 53% of wet deposition of NH(x) in Poland originates from national sources. Over the western part of Poland and mountainous areas in the south, transboundary transport can contribute over 80% of total (dry + wet) NH(x) deposition. The spatial pattern of the relative contribution of

  5. Optimization the condition of electrochemical deposition platinum nanocatalyst assisted with citric acid root%柠檬酸根辅助电沉积制备铂纳米粒子及其制备条件的优化

    Institute of Scientific and Technical Information of China (English)

    金碧瑶; 赵莲花

    2012-01-01

    An indium tin oxide(ITO) electrode is used as the substrate for supporting Pt particles prepared by potentiostatic method with citric acid root.By changing the applied potential,citric acid sodium concentration,precursor concentration and electrolyte concentration to optimize platinum nanoparticles preparation conditions.Using X-ray diffraction(XRD) to represent the crystal phase structure of Pt particle deposited on the ITO,using cycle volt ampere(CV) to determine the electric catalytic oxidation performance of Pt/ITO electrode in acid medium.The experimental results show that the preparation conditions of better electrocatalytic performance of the platinum nanoparticles is the applied potential of-0.3V,H2PtCl6 concentration is 0.8 mmol/L,citric acid sodium concentration is 20 mmol/L and electrolyte HClO4 concentration is 0.1 mol/L.%以氧化铟锡(ITO)透明导电玻璃为基体,在柠檬酸根存在下,采用恒电位电化学沉积法制备铂纳米粒子,并通过改变施加电位、柠檬酸钠浓度、前驱体浓度和电解质浓度来优化铂纳米粒子的制备条件.利用X射线衍射(XRD)表征在ITO表面沉积的Pt颗粒的晶相结构,并运用循环伏安法(CV)测定Pt/ITO电极在酸性介质中的电催化氧化性能.实验结果表明,在施加电位为-0.3V、H2PtCl6浓度为0.8mmol/L、柠檬酸钠浓度为20mmol/L和电解质HClO4浓度为0.1mol/L的条件下,制备出的铂纳米粒子的电催化性能较好.

  6. On the structure of gradient Yamabe solitons

    CERN Document Server

    Cao, Huai-Dong; Zhang, Yingying

    2011-01-01

    We show that every complete nontrivial gradient Yamabe soliton admits a special global warped product structure with a one-dimensional base. Based on this, we prove a general classification theorem for complete nontrivial locally conformally flat gradient Yamabe solitons.

  7. Properties of electrodeposited amorphous Fe-Ni-W alloy deposits

    Institute of Scientific and Technical Information of China (English)

    HE Feng-jiao; WANG Miao; LU Xin

    2006-01-01

    A new technique of electroplating amorphous Fe-Ni-W alloy deposits was proposed. The structure and morphology of Fe-Ni-W alloy deposit were detected by XRD and SEM. The friction and wear behavior of Fe-Ni-W alloy deposit were studied and compared with that of chromium deposit. The corrosion properties against 5% sodium chloride, 5% sulfuric acid and 5% sodium hydroxide were also discussed. The experimental results indicate that Fe-Ni-W alloy deposits have superior properties against wear than hard chromium deposits under dry sliding condition. Under oil sliding condition, except their better wear resistance, the deposits can protect their counterparts against wear. The deposits plated on brass and AISI 1045 steel show good behavior against corrosion of 5% sodium chloride, 5% sulfuric acid and 5% sodium hydroxide. The bath of electroplating amorphous Fe-Ni-W alloy deposits is environmentally friendly and would find widely use in industry.

  8. Application of phenomenological analysis in fused deposition modeling system based on polylactic acid%唯象分析法在聚乳酸熔融沉积成型系统中的应用

    Institute of Scientific and Technical Information of China (English)

    潘鑫龙; 陈元枝; 姜文英

    2014-01-01

    针对可降解生物材料聚乳酸在熔融沉积成型中的成型精度问题,运用唯象分析法,结合聚乳酸的物理特性与快速成型技术,计算聚乳酸快速成型速度参数。采用近似线性加速控制优化算法,对复杂的根号运算作泰勒级数近似法处理,降低对处理器的要求和内存的占用。以PiBot为实验平台,验证了唯象分析计算和近似线性加速理论的正确性和有效性。%According to the polylactic acid biodegradable material applied to fused deposition modeling technology,the mold-ing accuracy problems are studied.The physical properties of polylactic acid with rapid prototyping technology are consid-ered by using the phenomenological analysis method.The speed parameters of the rapid prototyping technology based on PLA are calculated.To reducing the requirements for the processor and memory's occupancy,the complex root calculation is simplified by using the approximating linear ramp algorithms which adopt Taylor series approximation.The validity and ef-fectiveness of the phenomenological analysis calculation and the approximating linear ramp theory is validated by the experi-mental platform of PiBot.

  9. Light scattering from suspensions under external gradients

    OpenAIRE

    Bonet i Avalos, Josep; Rubí Capaceti, José Miguel; Rodríguez, R.; Pérez Madrid, Agustín

    1990-01-01

    We analyze the light-scattering spectrum of a suspension in a viscoelastic fluid under density and velocity gradients. When a density gradient is present, the dynamic structure factor exhibits universality in the sense that its expression depends only on the reduced frequency and the reduced density gradient. For a velocity gradient, however, the universality breaks down. In this last case we have found a transition point from one to three characteristic frequencies in the spectrum, which is ...

  10. Gradient Flow Convolutive Blind Source Separation

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Nielsen, Chinton Møller

    2004-01-01

    Experiments have shown that the performance of instantaneous gradient flow beamforming by Cauwenberghs et al. is reduced significantly in reverberant conditions. By expanding the gradient flow principle to convolutive mixtures, separation in a reverberant environment is possible. By use of a circ......Experiments have shown that the performance of instantaneous gradient flow beamforming by Cauwenberghs et al. is reduced significantly in reverberant conditions. By expanding the gradient flow principle to convolutive mixtures, separation in a reverberant environment is possible. By use...

  11. Community and ecosystem responses to elevational gradients

    DEFF Research Database (Denmark)

    Sundqvist, Maja K.; Sanders, Nate; Wardle, David A.

    2013-01-01

    Community structure and ecosystem processes often vary along elevational gradients. Their responses to elevation are commonly driven by changes in temperature, and many community- and ecosystem-level variables therefore frequently respond similarly to elevation across contrasting gradients. There...... using elevational gradients for understanding community and ecosystem responses to global climate change at much larger spatial and temporal scales than is possible through conventional ecological experiments. However, future studies that integrate elevational gradient approaches with experimental...

  12. An education gradient in health, a health gradient in education, or a confounded gradient in both?

    Science.gov (United States)

    Lynch, Jamie L; von Hippel, Paul T

    2016-04-01

    There is a positive gradient associating educational attainment with health, yet the explanation for this gradient is not clear. Does higher education improve health (causation)? Do the healthy become highly educated (selection)? Or do good health and high educational attainment both result from advantages established early in the life course (confounding)? This study evaluates these competing explanations by tracking changes in educational attainment and Self-rated Health (SRH) from age 15 to age 31 in the National Longitudinal Study of Youth, 1997 cohort. Ordinal logistic regression confirms that high-SRH adolescents are more likely to become highly educated. This is partly because adolescent SRH is associated with early advantages including adolescents' academic performance, college plans, and family background (confounding); however, net of these confounders adolescent SRH still predicts adult educational attainment (selection). Fixed-effects longitudinal regression shows that educational attainment has little causal effect on SRH at age 31. Completion of a high school diploma or associate's degree has no effect on SRH, while completion of a bachelor's or graduate degree have effects that, though significant, are quite small (less than 0.1 points on a 5-point scale). While it is possible that educational attainment would have greater effect on health at older ages, at age 31 what we see is a health gradient in education, shaped primarily by selection and confounding rather than by a causal effect of education on health.

  13. Second order gradient ascent pulse engineering

    CERN Document Server

    de Fouquieres, P; Glaser, S J; Kuprov, Ilya

    2011-01-01

    We report some improvements to the gradient ascent pulse engineering (GRAPE) algorithm for optimal control of quantum systems. These include more accurate gradients, convergence acceleration using the BFGS quasi-Newton algorithm as well as faster control derivative calculation algorithms. In all test systems, the wall clock time and the convergence rates show a considerable improvement over the approximate gradient ascent.

  14. On the classification of gradient Ricci solitons

    OpenAIRE

    Petersen, Peter; Wylie, William

    2007-01-01

    We show that the only complete shrinking gradient Ricci solitons with vanishing Weyl tensor are quotients of the standard ones. This gives a new proof of the Hamilton-Ivey-Perel'man classification of 3-dimensional shrinking gradient solitons. We also prove a classification for expanding gradient Ricci solitons with constant scalar curvature and suitably decaying Weyl tensor.

  15. The effect of mixing on metallicity gradients in the ICM

    CERN Document Server

    Brüggen, M

    2002-01-01

    It is generally argued that most clusters of galaxies host cooling flows in which radiative cooling in the centre causes a slow inflow. However, recent observations by Chandra and XMM conflict with the predicted cooling flow rates. It has been suggested that radio jets that are situated at the centre of clusters of galaxies can assist in reducing the deposition of cold gas. Radio jets inflate cavities of hot radio plasma that rise through the cluster atmosphere and thus stir the intra-cluster medium. In this letter it is investigated whether this scenario is consistent with the pronounced metallicity gradients that have been observed in the cores of clusters.

  16. Deposit model for volcanogenic uranium deposits

    Science.gov (United States)

    Breit, George N.; Hall, Susan M.

    2011-01-01

    Volcanism is a major contributor to the formation of important uranium deposits both close to centers of eruption and more distal as a result of deposition of ash with leachable uranium. Hydrothermal fluids that are driven by magmatic heat proximal to some volcanic centers directly form some deposits. These fluids leach uranium from U-bearing silicic volcanic rocks and concentrate it at sites of deposition within veins, stockworks, breccias, volcaniclastic rocks, and lacustrine caldera sediments. The volcanogenic uranium deposit model presented here summarizes attributes of those deposits and follows the focus of the International Atomic Energy Agency caldera-hosted uranium deposit model. Although inferred by some to have a volcanic component to their origin, iron oxide-copper-gold deposits with economically recoverable uranium contents are not considered in this model.

  17. Oil shales, evaporites and ore deposits

    Science.gov (United States)

    Eugster, Hans P.

    1985-03-01

    The relationships between oil shales, evaporites and sedimentary ore deposits can be classified in terms of stratigraphic and geochemical coherence. Oil shale and black shale deposition commonly follows continental red beds and is in turn followed by evaporite deposition. This transgressive-regressive sequence represents an orderly succession of depositional environments in space and time and results in stratigraphic coherence. The amount of organic carbon of a sediment depends on productivity and preservation, both of which are enhanced by saline environments. Work on Great Salt Lake. Utah, allows us to estimate that only 5% of TOC originally deposited is preserved. Inorganic carbonate production is similar to TOC production, but preservation is much higher. Oil shales and black shales commonly are enriched in heavy metals through scavenging by biogenic particles and complexation by organic matter. Ore deposits are formed from such rocks through secondary enrichment processes, establishing a geochemical coherence between oil shales and ore deposits. The Permian Kupferschiefer of N. Europe is used as an example to define a Kupferschiefer type (KST) deposit. Here oxygenated brines in contact with red beds become acidified through mineral precipitation and acquire metals by dissolving oxide coatings. Oxidation of the black shale leads to further acid production and metal acquisition and eventually to sulfide deposition along a reducing front. In order to form ore bodies, the stratigraphic coherence of the red bed-black shale-evaporite succession must be joined by the geochemical coherence of the ore body-evaporite-black shale association. The Cretaceous Cu-Zn deposits of Angola, the Zambian Copperbelt as well as the Creta, Oklahoma, deposits are other KST examples. In the Zambian Copperbelt, evaporites are indicated by the carbonate lenticles thought to be pseudomorphs after gypsum-anhydrite nodules. MVT deposits are also deposited by acid brines, but at more

  18. Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems

    International Nuclear Information System (INIS)

    Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3–7.3 kg N ha−1 yr−1) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Net ammonification and nitrification (which dominated N-mineralization) were reduced and increased, respectively, by N fertilization, suggesting alterations in the N cycle. Soil organic C content, C:N ratios and the activity of β-glucosidase decreased along the extant gradient in most locations. Our results suggest that semiarid soils in low-productivity sites are unable to store additional N inputs, and that are also unable to mitigate increasing C emissions when experiencing increased N deposition. -- Highlights: •Soil organic N does not increase along the extant N deposition gradient. •Reduced N fixation is related to compositional shifts in soil cyanobacteria community. •Nitrogen cycling is altered by simulated N deposition. •Soil organic C content decrease along the extant N deposition gradient. •Semiarid soils are unable to mitigate CO2 emissions after increased N deposition. -- N deposition alters N cycling and reduces soil C content in semiarid Mediterranean ecosystems

  19. Method of depositing a high-emissivity layer

    Science.gov (United States)

    Wickersham, Charles E.; Foster, Ellis L.

    1983-01-01

    A method of depositing a high-emissivity layer on a substrate comprising RF sputter deposition of a carbide-containing target in an atmosphere of a hydrocarbon gas and a noble gas. As the carbide is deposited on the substrate the hydrocarbon gas decomposes to hydrogen and carbon. The carbon deposits on the target and substrate causing a carbide/carbon composition gradient to form on the substrate. At a sufficiently high partial pressure of hydrocarbon gas, a film of high-emissivity pure carbon will eventually form over the substrate.

  20. Plasma sputtering system for deposition of thin film combinatorial libraries

    Science.gov (United States)

    Cooper, James S.; Zhang, Guanghai; McGinn, Paul J.

    2005-06-01

    The design of a plasma sputtering system for the deposition of combinatorial libraries is described. A rotating carousel is used to position shadow masks between the targets and the substrate. Multilayer films are built up by depositing sequentially through various masks. Postdeposition annealing is used to promote interdiffusion of the layered structures. Either discrete or compositional gradient libraries can be deposited in this system. Samples appropriate for characterization with a scanning electrochemical microscope or a multichannel microelectrode array system can be produced. The properties of some deposited Pt-Ru films for fuel cell applications are described.

  1. Molybdenum sputtering film characterization for high gradient accelerating structures

    Institute of Scientific and Technical Information of China (English)

    S.Bini; B.Spataro; A.Marcelli; S.Sarti; V.A.Dolgashev; S.Tantawi; A.D.Yeremian

    2013-01-01

    Technological advancements are strongly required to fulfill the demands of new accelerator devices with the highest accelerating gradients and operation reliability for the future colliders.To this purpose an extensive R&D regarding molybdenum coatings on copper is in progress.In this contribution we describe chemical composition,deposition quality and resistivity properties of different molybdenum coatings obtained via sputtering.The deposited films are thick metallic disorder layers with different resistivity values above and below the molibdenum dioxide reference value.Chemical and electrical properties of these sputtered coatings have been characterized by Rutherford backscattering,XANES and photoemission spectroscopy.We will also consider multiple cells standing wave section coated by a molybdenum layer designed to improve the performance of X-Band accelerating systems.

  2. NIF optics phase gradient specfication

    Energy Technology Data Exchange (ETDEWEB)

    Williams, W.; Auerbach, J.; Hunt, J.; Lawson, L.; Manes, K.; Orth, C.; Sacks, R.; Trenholme, J.; Wegner, P.

    1997-05-02

    A root-mean-square (rms) phase gradient specification seems to allow a good connection between the NIP optics quality and focal spot requirements. Measurements on Beamlet optics individually, and as a chain, indicate they meet the assumptions necessary to use this specification, and that they have a typical rms phase gradient of {approximately}80 {angstrom}/cm. This may be sufficient for NIP to meet the proposed Stockpile Stewardship Management Program (SSMP) requirements of 80% of a high- power beam within a 200-250 micron diameter spot. Uncertainties include, especially, the scale length of the optics phase noise, the ability of the adaptive optic to correct against pump-induced distortions and optics noise, and the possibility of finding mitigation techniques against whole-beam self-focusing (e.g. a pre- correction optic). Further work is needed in these areas to better determine the NIF specifications. This memo is a written summary of a presentation on this topic given by W. Williams 24 April 1997 to NIP and LS&T personnel.

  3. Strain gradient effects on cyclic plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2010-01-01

    Size effects on the cyclic shear response are studied numerically using a recent higher order strain gradient visco-plasticity theory accounting for both dissipative and energetic gradient hardening. Numerical investigations of the response under cyclic pure shear and shear of a finite slab between...... rigid platens have been carried out, using the finite element method. It is shown for elastic–perfectly plastic solids how dissipative gradient effects lead to increased yield strength, whereas energetic gradient contributions lead to increased hardening as well as a Bauschinger effect. For linearly...... hardening materials it is quantified how dissipative and energetic gradient effects promote hardening above that of conventional predictions. Usually, increased hardening is attributed to energetic gradient effects, but here it is found that also dissipative gradient effects lead to additional hardening in...

  4. 氮沉降影响下酸性森林土壤中水溶性有机氮的分布特征%DISTRIBUTION PATTERN OF WATER SOLUBLE ORGANIC NITROGEN IN ACIDIC FOREST SOILS RECEIVING NITROGEN DEPOSITION

    Institute of Scientific and Technical Information of China (English)

    郭景恒; 张逸; 何骞; 相秀娟

    2011-01-01

    选取贵州雷公山(LGS)和重庆铁山坪(TSP)两个氮沉降量具有明显差异的森林小流域,对土壤中水溶性有机氮(WSON)的分布特征进行了对比研究.在氮沉降较低的LGS流域土壤水中WSON占总氮的比例可达30%—60%,显著高于氮沉降高的TSP流域.TSP流域土壤浸提液中WSON的比例相较于土壤水有显著增加,说明该流域中WSON多附着于土壤表面,流动性较弱.在0—90 cm典型剖面内,TSP流域WSON的比例显著高于LGS流域.两剖面中WSON的比例均在中部(30—60 cm)达到最高值,分别为35.37%和5%Distribution pattern of water soluble organic nitrogen(WSON) in acidic forest soils was investigated in two selected catchments.In Leigongshan(LGS) catchment receiving lower nitrogen deposition,WSON was the important fraction of total dissolved nitrogen(TDN) in soil water,with the percentage ranging from 30% to 60%.However,the percentage was less than 10% in Teishanping(TSP) catchment receiving higher nitrogen deposition.In soil extracts of TSP catchment WSON percentage increased substantially,which indicates that WSON in this catchment mostly adsorbed on soil solid phase with low mobility.In the typical soil profiles(0—90 cm),WSON percentage in TSP catchment was significantly higher than that in LGS catchment.In LGS and TSP catchment,WSON percentage reached its maximum in the middle depth(30—60 cm) with the values of 35.37% and 55.82%,respectively.Vertical change of WSON was not synchronous with water soluble organic carbon(WSOC) in the investigated soil depth range.In the middle depth,C/N ratio of water soluble organic matter(WSOM) reached minimum.In the middle and bottom depth(30—90 cm),C/N ratio in TSP profile was significantly lower than in LGS profile,indicating higher nitrogen enrichment of WSOM in TSP catchment.

  5. Metallization on FDM Parts Using the Chemical Deposition Technique

    Directory of Open Access Journals (Sweden)

    Azhar Equbal

    2014-08-01

    Full Text Available Metallization of ABS (acrylonitrile-butadiene-styrene parts has been studied on flat part surfaces. These parts are fabricated on an FDM (fused deposition modeling machine using the layer-wise deposition principle using ABS as a part material. Electroless copper deposition on ABS parts was performed using two different surface preparation processes, namely ABS parts prepared using chromic acid for etching and ABS parts prepared using a solution mixture of sulphuric acid and hydrogen peroxide (H2SO4/H2O2 for etching. After surface preparations using these routes, copper (Cu is deposited electrolessly using four different acidic baths. The acidic baths used are 5 wt% CuSO4 (copper sulfate with 15 wt% of individual acids, namely HF (hydrofluoric acid, H2SO4 (sulphuric acid, H3PO4 (phosphoric acid and CH3COOH (acetic acid. Cu deposition under different acidic baths used for both the routes is presented and compared based on their electrical performance, scanning electron microscopy (SEM and energy dispersive X-ray spectrometry (EDS. The result shows that chromic acid etched samples show better electrical performance and Cu deposition in comparison to samples etched via H2SO4/H2O2.

  6. Physical properties of wax deposits on the walls of crude pipelines

    Institute of Scientific and Technical Information of China (English)

    Huang Qiyu; Wang Jifeng; Zhang Jinjun

    2009-01-01

    Wax deposits on the wall of a crude oil pipeline are a solid wax network of fine crystals, filled with oil, resin, asphaitene and other impurities. In this paper, a series of experiments on wax deposition in a laboratory flow loop were performed under different conditions (flow rate, temperature differential between crude oil and pipeline wall, and dissolved wax concentration gradient), and the wax deposits were analyzed, so quantitative relationships among wax content, wax appearance temperature (WAT), shear stress, and radial concentration gradient of dissolved wax at the solid/liquid interface were obtained. Finally, a model was established to predict WAT and the wax content of the deposit.

  7. Strength gradient enhances fatigue resistance of steels

    Science.gov (United States)

    Ma, Zhiwei; Liu, Jiabin; Wang, Gang; Wang, Hongtao; Wei, Yujie; Gao, Huajian

    2016-02-01

    Steels are heavily used in infrastructure and the transportation industry, and enhancing their fatigue resistance is a major challenge in materials engineering. In this study, by introducing a gradient microstructure into 304 austenitic steel, which is one of the most widely used types of stainless steel, we show that a strength gradient substantially enhances the fatigue life of the material. Pre-notched samples with negative strength gradients in front of the notch’s tip endure many more fatigue cycles than do samples with positive strength gradients during the crack initiation stage, and samples with either type of gradient perform better than do gradient-free samples with the same average yield strength. However, as a crack grows, samples with positive strength gradients exhibit better resistance to fatigue crack propagation than do samples with negative gradients or no gradient. This study demonstrates a simple and promising strategy for using gradient structures to enhance the fatigue resistance of materials and complements related studies of strength and ductility.

  8. Combinational concentration gradient confinement through stagnation flow.

    Science.gov (United States)

    Alicia, Toh G G; Yang, Chun; Wang, Zhiping; Nguyen, Nam-Trung

    2016-01-21

    Concentration gradient generation in microfluidics is typically constrained by two conflicting mass transport requirements: short characteristic times (τ) for precise temporal control of concentration gradients but at the expense of high flow rates and hence, high flow shear stresses (σ). To decouple the limitations from these parameters, here we propose the use of stagnation flows to confine concentration gradients within large velocity gradients that surround the stagnation point. We developed a modified cross-slot (MCS) device capable of feeding binary and combinational concentration sources in stagnation flows. We show that across the velocity well, source-sink pairs can form permanent concentration gradients. As source-sink concentration pairs are continuously supplied to the MCS, a permanently stable concentration gradient can be generated. Tuning the flow rates directly controls the velocity gradients, and hence the stagnation point location, allowing the confined concentration gradient to be focused. In addition, the flow rate ratio within the MCS rapidly controls (τ ∼ 50 ms) the location of the stagnation point and the confined combinational concentration gradients at low flow shear (0.2 Pa < σ < 2.9 Pa). The MCS device described in this study establishes the method for using stagnation flows to rapidly generate and position low shear combinational concentration gradients for shear sensitive biological assays. PMID:26671507

  9. Characterization and simulation on antireflective coating of amorphous silicon oxide thin films with gradient refractive index

    Science.gov (United States)

    Huang, Lu; Jin, Qi; Qu, Xingling; Jin, Jing; Jiang, Chaochao; Yang, Weiguang; Wang, Linjun; Shi, Weimin

    2016-08-01

    The optical reflective properties of silicon oxide (SixOy) thin films with gradient refractive index are studied both theoretically and experimentally. The thin films are widely used in photovoltaic as antireflective coatings (ARCs). An effective finite difference time domain (FDTD) model is built to find the optimized reflection spectra corresponding to structure of SixOy ARCs with gradient refractive index. Based on the simulation analysis, it shows the variation of reflection spectra with gradient refractive index distribution. The gradient refractive index of SixOy ARCs can be obtained in adjustment of SiH4 to N2O ratio by plasma-enhanced chemical vapor deposition (PECVD) system. The optimized reflection spectra measured by UV-visible spectroscopy confirms to agree well with that simulated by FDTD method.

  10. Wnt Secretion and Gradient Formation

    Directory of Open Access Journals (Sweden)

    Vladimir L. Katanaev

    2013-03-01

    Full Text Available Concentration gradients formed by the lipid-modified morphogens of the Wnt family are known for their pivotal roles during embryogenesis and adult tissue homeostasis. Wnt morphogens are also implicated in a variety of human diseases, especially cancer. Therefore, the signaling cascades triggered by Wnts have received considerable attention during recent decades. However, how Wnts are secreted and how concentration gradients are formed remains poorly understood. The use of model organisms such as Drosophila melanogaster has provided important advances in this area. For instance, we have previously shown that the lipid raft-associated reggie/flotillin proteins influence Wnt secretion and spreading in Drosophila. Our work supports the notion that producing cells secrete Wnt molecules in at least two pools: a poorly diffusible one and a reggie/flotillin-dependent highly diffusible pool which allows morphogen spreading over long distances away from its source of production. Here we revise the current views of Wnt secretion and spreading, and propose two models for the role of the reggie/flotillin proteins in these processes: (i reggies/flotillins regulate the basolateral endocytosis of the poorly diffusible, membrane-bound Wnt pool, which is then sorted and secreted to apical compartments for long-range diffusion, and (ii lipid rafts organized by reggies/flotillins serve as “dating points” where extracellular Wnt transiently interacts with lipoprotein receptors to allow its capture and further spreading via lipoprotein particles. We further discuss these processes in the context of human breast cancer. A better understanding of these phenomena may be relevant for identification of novel drug targets and therapeutic strategies.

  11. Molecular mechanisms for generating transmembrane proton gradients.

    Science.gov (United States)

    Gunner, M R; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.

  12. Accuracy of cuticular resistance parameterizations in ammonia dry deposition models

    Science.gov (United States)

    Schrader, Frederik; Brümmer, Christian; Richter, Undine; Fléchard, Chris; Wichink Kruit, Roy; Erisman, Jan Willem

    2016-04-01

    Accurate representation of total reactive nitrogen (Nr) exchange between ecosystems and the atmosphere is a crucial part of modern air quality models. However, bi-directional exchange of ammonia (NH3), the dominant Nr species in agricultural landscapes, still poses a major source of uncertainty in these models, where especially the treatment of non-stomatal pathways (e.g. exchange with wet leaf surfaces or the ground layer) can be challenging. While complex dynamic leaf surface chemistry models have been shown to successfully reproduce measured ammonia fluxes on the field scale, computational restraints and the lack of necessary input data have so far limited their application in larger scale simulations. A variety of different approaches to modelling dry deposition to leaf surfaces with simplified steady-state parameterizations have therefore arisen in the recent literature. We present a performance assessment of selected cuticular resistance parameterizations by comparing them with ammonia deposition measurements by means of eddy covariance (EC) and the aerodynamic gradient method (AGM) at a number of semi-natural and grassland sites in Europe. First results indicate that using a state-of-the-art uni-directional approach tends to overestimate and using a bi-directional cuticular compensation point approach tends to underestimate cuticular resistance in some cases, consequently leading to systematic errors in the resulting flux estimates. Using the uni-directional model, situations where low ratios of total atmospheric acids to NH3 concentration occur lead to fairly high minimum cuticular resistances, limiting predicted downward fluxes in conditions usually favouring deposition. On the other hand, the bi-directional model used here features a seasonal cycle of external leaf surface emission potentials that can lead to comparably low effective resistance estimates under warm and wet conditions, when in practice an expected increase in the compensation point due to

  13. Mathematics of Experimentally Generated Chemoattractant Gradients.

    Science.gov (United States)

    Postma, Marten; van Haastert, Peter J M

    2016-01-01

    Many eukaryotic cells move in the direction of a chemical gradient. Several assays have been developed to measure this chemotactic response, but no complete mathematical models of the spatial and temporal gradients are available to describe the fundamental principles of chemotaxis. Here we provide analytical solutions for the gradients formed by release of chemoattractant from a point source by passive diffusion or forced flow (micropipettes) and gradients formed by laminar diffusion in a Zigmond chamber. The results show that gradients delivered with a micropipette are formed nearly instantaneously, are very steep close to the pipette, and have a steepness that is strongly dependent on the distance from the pipette. In contrast, gradients in a Zigmond chamber are formed more slowly, are nearly independent of the distance from the source, and resemble the temporal and spatial properties of the natural cAMP wave that Dictyostelium cells experience during cell aggregation. PMID:27271915

  14. Mathematics of Experimentally Generated Chemoattractant Gradients.

    Science.gov (United States)

    Postma, Marten; van Haastert, Peter J M

    2016-01-01

    Many eukaryotic cells move in the direction of a chemical gradient. Several assays have been developed to measure this chemotactic response, but no complete mathematical models of the spatial and temporal gradients are available to describe the fundamental principles of chemotaxis. Here we provide analytical solutions for the gradients formed by release of chemoattractant from a point source by passive diffusion or forced flow (micropipettes) and gradients formed by laminar diffusion in a Zigmond chamber. The results show that gradients delivered with a micropipette are formed nearly instantaneously, are very steep close to the pipette, and have a steepness that is strongly dependent on the distance from the pipette. In contrast, gradients in a Zigmond chamber are formed more slowly, are nearly independent of the distance from the source, and resemble the temporal and spatial properties of the natural cAMP wave that Dictyostelium cells experience during cell aggregation.

  15. Variation in the content and distribution of biomarkers in two closely situated peat and lignite deposits

    Energy Technology Data Exchange (ETDEWEB)

    Del Rio, J.C.; Gonzalez-Vila, F.J.; Martin, F. (Instituto de Recursos Naturales y Agrobiologia de Sevilla, Seville (Spain))

    1992-01-01

    A peat and two lignite samples taken from closely situated deposits in the Granada Basin (South Spain) were analysed for their lipid composition. Variations in the distributions and abundances of various compound classes including normal, branched and unsaturated fatty acids, aliphatic hydrocarbons, aliphatic and steroid alcohols and ketones, aldehydes, diterpenoids and triterpenoids suggest that a gradient in maturity exists among the samples indicating that the lignites were generally more mature than the peat. In spite of their similar rank, a different hopane distribution was observed between both lignite samples. Source materials include contributions from terrigenous (coniferous) higher plants as well as microbial sources. A possible contribution from marine phytoplankton can also be inferred in the lignite on the basis of the sterol distribution. 69 refs., 6 figs., 4 tabs.

  16. Electro-spark deposition technology

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.N. [Pacific Northwest Lab., WA (United States)

    1996-08-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated as one of the enabling technologies for advanced energy systems. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that promises an order of magnitude increase in deposition rates and achievable coating thicknesses. Since this regime borders on and exceeds the normal operating limits of existing ESD electronic equipment, development is in progress to produce equipment that can consistently and reliably achieve these conditions for a broad range of materials. Progress so far has resulted in a consistent 500% increase in deposition rates, and greater rates still are anticipated. Technology transfer activities are a significant portion of the ESD program effort. Notable successes now include the start-up of a new business to commercialize the ESD technology, the incorporation of the process into the operations of a major gas turbine manufacturer, major new applications in gas turbine blade and steam turbine blade protection and repair, and in military, medical, metal-working, and recreational equipment applications.

  17. Interpretation of the reduced density gradient

    OpenAIRE

    Boto, Roberto A.; Contreras-García, Julia; Tierny, Julien; Piquemal, Jean-Philip

    2015-01-01

    An interpretation of the reduced density gradient in terms of the bosonic kinetic energy density is presented. Contrary to other bonding indicators based on the kinetic energy density such as the localised orbital locator (LOL) or the electron localization function (ELF), the reduced density gradient is not only able to identify covalent bondings, but also ionic and non-covalent interactions. This study reveals that the critical points of the reduced density gradient are closely connected wit...

  18. Simulation of Indoor Fine Suspension Particle Deposition

    Science.gov (United States)

    Li, K. Q.; Gong, G. C.; Zou, S. H.

    In this paper, the migration and deposition of particles are simulated using the Moment Dynamic Equation (MDE). Indoor fine suspension particle depositions and particle distribution function are obtained. Gas phase flow is simulated by v 2 - f model. The simulated results of particle concentration profiles show that a uniform concentration exists in the middle region of the room with a low supplying speed. At the same time, the total number of partciels deposited is also obtained using Gradient diffusion model. Through the comparison of velocity predictions among several CFD k-ɛ models and v 2 -f model and experimental data, it is concluded that the results obtained by v 2 -f model more accurately approximate the experimental data. So that the MDE combined v 2 -f model will gain in popularity amongst building engineers and it will gradually be adopted as an attractive alternative tool to predict contaminant particle dispersion and distribution.

  19. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...... the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  20. Wireless SAW Based Temperature Gradient Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Prime Photonics proposes design and development of a surface acoustic wave (SAW) based temperature gradient sensor for instrumentation of thermal protection systems...

  1. INFLUENCES OF SLOPE GRADIENT ON SOIL EROSION

    Institute of Scientific and Technical Information of China (English)

    刘青泉; 陈力; 李家春

    2001-01-01

    The main factors influencing soil erosion include the net rain excess, the water depth, the velocity, the shear stress of overland flows , and the erosion-resisting capacity of soil. The laws of these factors varying with the slope gradient were investigated by using the kinematic wave theory. Furthermore, the critical slope gradient of erosion was driven. The analysis shows that the critical slope gradient of soil erosion is dependent on grain size , soil bulk density , surface roughness, runoff length, net rain excess, and the friction coefficient of soil, etc. The critical slope gradient has been estimated theoretically with its range between 41. 5 °~ 50°.

  2. A new pulsed laser deposition technique: scanning multi-component pulsed laser deposition method.

    Science.gov (United States)

    Fischer, D; de la Fuente, G F; Jansen, M

    2012-04-01

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C. PMID:22559543

  3. Low-fluorine Stockwork Molybdenite Deposits

    Science.gov (United States)

    Ludington, Steve; Hammarstrom, Jane; Piatak, Nadine M.

    2009-01-01

    Low-fluorine stockwork molybdenite deposits are closely related to porphyry copper deposits, being similar in their tectonic setting (continental volcanic arc) and the petrology (calc-alkaline) of associated igneous rock types. They are mainly restricted to the Cordillera of western Canada and the northwest United States, and their distribution elsewhere in the world may be limited. The deposits consist of stockwork bodies of molybdenite-bearing quartz veinlets that are present in and around the upper parts of intermediate to felsic intrusions. The deposits are relatively low grade (0.05 to 0.2 percent Mo), but relatively large, commonly >50 million tons. The source plutons for these deposits range from granodiorite to granite in composition; the deposits primarily form in continental margin subduction-related magmatic arcs, often concurrent with formation of nearby porphyry copper deposits. Oxidation of pyrite in unmined deposits or in tailings and waste rock during weathering can lead to development of acid-rock drainage and limonite-rich gossans. Waters associated with low-fluorine stockwork molybdenite deposits tend to be nearly neutral in pH; variable in concentrations of molybdenum (10,000 ug/L); below regulatory guidelines for copper, iron, lead, zinc, and mercury; and locally may exceed guidelines for arsenic, cadmium, and selenium.

  4. Performance of spray deposited poly [N-9 Double-Prime -hepta-decanyl-2,7-carbazole-alt-5,5-(4 Prime ,7 Prime -di-2-thienyl-2 Prime ,1 Prime , 3 Prime -benzothiadiazole)]/[6,6]-phenyl-C61-butyric acid methyl ester blend active layer based bulk heterojunction organic solar cell devices

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Leona [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan); Babu, R. Ramesh [Crystal Growth and Thin Film Laboratory, Department of Physics, Bharathidasan University, Tiruchirappalli-620 024, Tamil Nadu (India); Kannappan, Santhakumar; Kojima, Kenzo; Mizutani, Teruyoshi [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan); Ochiai, Shizuyasu, E-mail: ochiai@aitech.ac.jp [Department of Electrical Engineering, Aichi Institute of Technology, Toyota, Aichi 470-0392 (Japan)

    2012-01-31

    Bulk heterojunction organic solar cell devices were fabricated using the spray deposited poly [N-9 Double-Prime -hepta-decanyl-2,7-carbazole-alt-5,5-(4 Prime ,7 Prime -di-2-thienyl-2 Prime ,1 Prime , 3 Prime -benzothiadiazole)]/[6,6]-phenyl-C61-butyric acid methyl ester blend active layer. The spray coating parameters such as spraying time, substrate-nozzle distance for the deposition of active layers were analyzed. Optical absorption of the active layers was analyzed using UV-visible spectral studies in the wavelength range from 300 to 800 nm. The surface morphology of the active layers deposited with different parameters was examined using atomic force microscopy. Surface morphology of the active layers deposited with the substrate-nozzle distance of 20 cm and for 20 s shows smooth morphology with peak-valley value of 4 nm. The devices fabricated using the selected active layer show overall power conversion efficiency of 1.08%. - Graphical abstract: Current-voltage (J-V) characteristics of spray deposited PCDTBT:PC{sub 61}BM active layer based solar cell device under illumination of AM 1.5 G, 100 mW/cm{sup 2}. Highlights: Black-Right-Pointing-Pointer Organic solar cells were fabricated using a spray deposited PCDTBT:PC61BM active layer. Black-Right-Pointing-Pointer The active layers deposited with spray conditions show flat morphology. Black-Right-Pointing-Pointer Using the selected active layers power conversion efficiency of 1.08% is obtained.

  5. Linking Slope Sedimentation, Gradient, Morphology, and Active Faulting: An Integrated Example from the Palos Verdes Slope, Southern California Borderland

    Science.gov (United States)

    Maier, K. L.; Brothers, D. S.; Paull, C. K.; McGann, M.; Caress, D. W.; Conrad, J. E.

    2015-12-01

    Seafloor gradient variations associated with restraining and releasing bends along the active (1.6-1.9 mm/yr) right-lateral Palos Verdes Fault appear to control Holocene sediment thickness, depositional environment, and morphodynamic processes along a section of the continental slope offshore Los Angeles, California. Autonomous underwater mapping vehicle (AUV), remotely operated vehicle (ROV), and shipboard methods were used to acquire a dense grid of high-resolution chirp profiles (150 m line spacing; 11 cm vertical resolution), multibeam bathymetry (2 m grid), and targeted sediment core samples (<2 m length). Detailed interpretation of Holocene deposits in the chirp profiles combined with radiocarbon dating and laser particle-size analyses allow correlation of Holocene sediment thickness and seafloor gradient with sediment gravity flow deposits. Holocene down-slope flows appear to have been generated by mass wasting processes, primarily on the upper slope (~100-200 m water depth) where shipboard multibeam bathymetry reveals submarine landslide headwall scarps in a region that has been isolated from terrigenous sediment sources throughout the Holocene. Submarine landslides appear to have transformed into sandy and organic-rich turbidity currents that created up-slope migrating sediment waves, a low relief (<5 m) fault-bounded channel, and a series of depocenters. A down-slope gradient profile and a Holocene isopach down-slope profile show that the primary depocenter occurs within a small pull-apart basin associated with a decrease in seafloor gradient of ~1.5°. Holocene sediment-flow deposits vary in number, thickness, and character with subtle changes in seabed gradient (<0.5°) and depositional environment. These results help quantify morphodynamic sensitivity to seafloor gradients and have implications for down-slope flow dynamics, deep-water depositional architecture, Holocene sediment, nutrient, and contaminant transport, and turbidite paleoseismology along

  6. An Inexpensive Digital Gradient Controller for HPLC.

    Science.gov (United States)

    Brady, James E.; Carr, Peter W.

    1983-01-01

    Use of gradient elution techniques in high performance liquid chromatography (HPLC) is often essential for direct separation of complex mixtures. Since most commercial controllers have features that are of marginal value for instructional purposes, a low-cost controller capable of illustrating essential features of gradient elution was developed.…

  7. Mathematics of Experimentally Generated Chemoattractant Gradients

    NARCIS (Netherlands)

    Postma, Marten; van Haastert, Peter J M; Jin, Tian; Hereld, Dale

    2016-01-01

    Many eukaryotic cells move in the direction of a chemical gradient. Several assays have been developed to measure this chemotactic response, but no complete mathematical models of the spatial and temporal gradients are available to describe the fundamental principles of chemotaxis. Here we provide a

  8. Newton's method in the context of gradients

    Directory of Open Access Journals (Sweden)

    John W. Neuberger

    2007-09-01

    Full Text Available This paper gives a common theoretical treatment for gradient and Newton type methods for general classes of problems. First, for Euler-Lagrange equations Newton's method is characterized as an (asymptotically optimal variable steepest descent method. Second, Sobolev gradient type minimization is developed for general problems using a continuous Newton method which takes into account a "boundary condition" operator.

  9. On 4-dimensional gradient shrinking solitons

    OpenAIRE

    Ni, Lei; Wallach, Nolan

    2007-01-01

    In this paper we classify the four dimensional gradient shrinking solitons under certain curvature conditions satisfied by all solitons arising from finite time singularities of Ricci flow on compact four manifolds with positive isotropic curvature. As a corollary we generalize a result of Perelman on three dimensional gradient shrinking solitons to dimension four.

  10. Microstrain Determination in Individual Grains of Laser Deposited Cladding Layers

    NARCIS (Netherlands)

    de Oliveira, Uazir O. B.; Ocelik, Vaclav; De Hosson, Jeff T. M.; Chandra, T; Tsuzaki, K; Militzer, M; Ravindran, C

    2007-01-01

    The laser cladding technique makes the deposition of thick metallic, wear and corrosion resistant coatings feasible on weaker substrates. During the process, localized high thermal gradients generate internal stresses that may cause cracking when these overcome the fracture stress. To explain the fo

  11. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Y; Mazzucato, E; Guttenfelder, W; Bell, R E; Domier, C W; LeBlanc, B P; Lee, K C; Luhmann Jr, N C; Smith, D R

    2011-03-21

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k⊥ρs ≤10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  12. Density Gradient Stabilization of Electron Temperature Gradient Driven Turbulence in a Spherical Tokamak

    International Nuclear Information System (INIS)

    In this letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k (perpendicular) ρs ∼< 10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of two decrease in the plasma effective thermal diffusivity.

  13. Dual fuel gradients in uranium silicide plates

    Energy Technology Data Exchange (ETDEWEB)

    Pace, B.W. [Babock and Wilcox, Lynchburg, VA (United States)

    1997-08-01

    Babcock & Wilcox has been able to achieve dual gradient plates with good repeatability in small lots of U{sub 3}Si{sub 2} plates. Improvements in homogeneity and other processing parameters and techniques have allowed the development of contoured fuel within the cladding. The most difficult obstacles to overcome have been the ability to evaluate the bidirectional fuel loadings in comparison to the perfect loading model and the different methods of instilling the gradients in the early compact stage. The overriding conclusion is that to control the contour of the fuel, a known relationship between the compact, the frames and final core gradient must exist. Therefore, further development in the creation and control of dual gradients in fuel plates will involve arriving at a plausible gradient requirement and building the correct model between the compact configuration and the final contoured loading requirements.

  14. Stellar Metallicity Gradients in SDSS galaxies

    CERN Document Server

    Roig, Benjamin; Yan, Renbin

    2015-01-01

    We infer stellar metallicity and abundance ratio gradients for a sample of red galaxies in the Sloan Digital Sky Survey (SDSS) Main galaxy sample. Because this sample does not have multiple spectra at various radii in a single galaxy, we measure these gradients statistically. We separate galaxies into stellar mass bins, stack their spectra in redshift bins, and calculate the measured absorption line indices in projected annuli by differencing spectra in neighboring redshift bins. After determining the line indices, we use stellar population modeling from the EZ\\_Ages software to calculate ages, metallicities, and abundance ratios within each annulus. Our data covers the central regions of these galaxies, out to slightly higher than $1 R_{e}$. We find detectable gradients in metallicity and relatively shallow gradients in abundance ratios, similar to results found for direct measurements of individual galaxies. The gradients are only weakly dependent on stellar mass, and this dependence is well-correlated with...

  15. Separation and identification of amino acids from lignite humic acids by thin layer chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Damian, L.; Marutoiu, C.; Niac, G.

    1985-07-01

    Thin layer chromatography with and without temperature gradient was used to identify ten amino acids in the humic acid hydrolysate of Rovinari lignite, using cellulose and volcanic tuff as stationary phases. The acids found were L-leucine, isoleucine, phenylalanine, L-valine, tyrosine, proline, L-alanine, glutamic acid, threonine and L-lysine. 8 references.

  16. The Removal of Iron From Hard Pulverised Kaolin by Dry High–Gradient Magnetic Separation

    OpenAIRE

    Chun, Yu Kang

    1995-01-01

    Deposits of hard kaolin are abundant in China, with kaolin content in the ore exceeding 95%. It is, however, rather difficult to remove iron from the ore. It was demonstrated that wet high–gradient magnetic separation is very efficient in removing the iron compounds from kaolin. For hard kaolin, however, dry high–gradient magnetic separation (HGMS) may be more suitable. To this end, we have developed a new type of dry HGMS device for laboratory use. The separation performance of the device wa...

  17. Study of the growth kinetics of biomimetically grown hydroxyapatite coatings in large gradient magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Ya-Jing; Liu, Yang-Yang [School of Life Sciences, Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi’an, 710072 (China); Institute of Special Environmental Biophysics, Northwestern Polytechnical University, Xi’an, 710072 (China); Yin, Da-Chuan, E-mail: yindc@nwpu.edu.cn [School of Life Sciences, Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi’an, 710072 (China); Institute of Special Environmental Biophysics, Northwestern Polytechnical University, Xi’an, 710072 (China)

    2015-10-01

    Highlights: • Inducing ability of self-assembly monolayers in large gradient magnetic fields. • Bonding information of functional groups obtained by first principles calculations. • The gravity fields affected the compositions of the apatite layers. - Abstract: Large gradient magnetic fields simultaneously provide both strong magnetic and simulated gravitational fields. Processes in such environments are subject to the influences of these two fields. Previous studies have shown that the deposition of hydroxyapatite (HAp) coatings induced by self-assembled monolayers (SAMs) is affected by large gradient magnetic fields. To further clarify the mechanism, we examined the effects of gravitational and magnetic fields on the deposition kinetics of the SAMs and the HAp coatings via surface analysis and molecular simulation. The chemical compositions of the SAMs and the HAp coatings in the fields were detected by X-ray photoelectron spectroscopy (XPS). The ability of the SAMs to induce the deposition of apatite was investigated via first principles calculations, which were performed to obtain information about the bonding interactions between the self-assembled functional groups and the –PO{sub 4}{sup 3−} ions in simulated body fluid (SBF). The experimental results showed that the fields affected the compositions of the apatite layers. The first principles calculation results showed that the –PO{sub 4}H{sup 2−} functional group exhibited a stronger ability to induce apatite deposition than the –COOH functional group. This result suggested that hydrogen phosphate root groups are better nucleation sites than carboxyl root groups.

  18. Atmospheric Deposition Modeling Results

    Data.gov (United States)

    U.S. Environmental Protection Agency — This asset provides data on model results for dry and total deposition of sulfur, nitrogen and base cation species. Components include deposition velocities, dry...

  19. Electro-Deposition Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The electro-deposition laboratory can electro-deposit various coatings onto small test samples and bench level prototypes. This facility provides the foundation for...

  20. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  1. Invasiveness of Campylopus introflexus in drift sands depends on nitrogen deposition and soil organic matter

    NARCIS (Netherlands)

    L.B. Sparrius; A.M. Kooijman

    2011-01-01

    Question: Does the neophyte moss Campylopus introflexus invade more often in drift sand pioneer vegetations under high nitrogen (N) deposition? Location: Fourteen inland dune reserves in The Netherlands over a gradient of atmospheric N deposition. Methods: A transect study, dispersal experiment and

  2. Atmospheric deposition maps for the Rocky Mountains

    Science.gov (United States)

    Nanus, L.; Campbell, D.H.; Ingersoll, G.P.; Clow, D.W.; Mast, M.A.

    2003-01-01

    Variability in atmospheric deposition across the Rocky Mountains is influenced by elevation, slope, aspect, and precipitation amount and by regional and local sources of air pollution. To improve estimates of deposition in mountainous regions, maps of average annual atmospheric deposition loadings of nitrate, sulfate, and acidity were developed for the Rocky Mountains by using spatial statistics. A parameter-elevation regressions on independent slopes model (PRISM) was incorporated to account for variations in precipitation amount over mountainous regions. Chemical data were obtained from the National Atmospheric Deposition Program/National Trends Network and from annual snowpack surveys conducted by the US Geological Survey and National Park Service, in cooperation with other Federal, State and local agencies. Surface concentration maps were created by ordinary kriging in a geographic information system, using a local trend and mathematical model to estimate the spatial variance. Atmospheric-deposition maps were constructed at 1-km resolution by multiplying surface concentrations from the kriged grid and estimates of precipitation amount from the PRISM model. Maps indicate an increasing spatial trend in concentration and deposition of the modeled constituents, particularly nitrate and sulfate, from north to south throughout the Rocky Mountains and identify hot-spots of atmospheric deposition that result from combined local and regional sources of air pollution. Highest nitrate (2.5-3.0kg/ha N) and sulfate (10.0-12.0kg/ha SO4) deposition is found in northern Colorado.

  3. Novel concepts in weld metal science: Role of gradients and composite structure

    Energy Technology Data Exchange (ETDEWEB)

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  4. Intracellular chemical gradients: morphing principle in bacteria

    Directory of Open Access Journals (Sweden)

    Endres Robert G

    2012-09-01

    Full Text Available Abstract Advances in computational biology allow systematic investigations to ascertain whether internal chemical gradients can be maintained in bacteria – an open question at the resolution limit of fluorescence microscopy. While it was previously believed that the small bacterial cell size and fast diffusion in the cytoplasm effectively remove any such gradient, a new computational study published in BMC Biophysics supports the emerging view that gradients can exist. The study arose from the recent observation that phosphorylated CtrA forms a gradient prior to cell division in Caulobacter crescentus, a bacterium known for its complicated cell cycle. Tropini et al. (2012 postulate that such gradients can provide an internal chemical compass, directing protein localization, cell division and cell development. More specifically, they describe biochemical and physical constraints on the formation of such gradients and explore a number of existing bacterial cell morphologies. These chemical gradients may limit in vitro analyses, and may ensure timing control and robustness to fluctuations during critical stages in cell development.

  5. Hideout in steam generator tube deposits

    International Nuclear Information System (INIS)

    Hideout in deposits on steam generator tubes was studied using tubes coated with magnetite. Hideout from sodium chloride solutions at 279 degrees C was followed using an on-line high-temperature conductivity probe, as well as by chemical analysis of solution samples from the autoclave in which the studies were done. Significant hideout was observed only at a heat flux greater than 200 kW/m2, corresponding to a temperature drop greater than 2 degrees C across the deposits. The concentration factor resulting from the hideout increased highly non-linearly with the heat flux (varying as high as the fourth power of the heat flux). The decrease in the apparent concentration factor with increasing deposit thickness suggested that the pores in the deposit were occupied by a mixture of steam and water, which is consistent with the conclusion from the thermal conductivity measurements on deposits in a separate study. Analyses of the deposits after the hideout tests showed no evidence of any hidden-out solute species, probably due to the concentrations being very near the detection limits and to their escape from the deposit as the tests were being ended. This study showed that hideout in deposits may concentrate solutes in the steam generator bulk water by a factor as high as 2 x 103. Corrosion was evident under the deposit in some tests, with some chromium enrichment on the surface of the tube. Chromium enrichment usually indicates an acidic environment, but the mobility required of chromium to become incorporated into the thick magnetite deposit may indicate corrosion under an alkaline environment. An alkaline environment could result from preferential accumulation of sodium in the solution in the deposit during the hideout process. (author)

  6. Sound beam manipulation based on temperature gradients

    International Nuclear Information System (INIS)

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking

  7. GRADIENT ENERGY DETECTION OF LSB STEGANOGRAPHY

    Institute of Scientific and Technical Information of China (English)

    Li Zhi; Sui Aifen; Niu Xinxin; Yang Yixian

    2005-01-01

    The spatial Least Significant Bit (LSB) steganography results in the alteration of the smooth characteristics between adjoining pixels of the raw image. The relation between the length of embedded message and the gradient energy is theoretically analyzed, and then a steganalysis and detection method, named Gradient Energy-Flipping Rate (GEFR) detection is proposed. Based on the analysis of the variation of the gradient energy, which results from the LSB steganography in color and grayscale image, the secret message embedded in the target image is detected, and the length of the embedded message is estimated. The method is proved effective and accurate by simulation (detection rate reaches 0.01bit per pixel).

  8. Colour and stellar population gradients in galaxies

    CERN Document Server

    Tortora, C; Cardone, V F; Capaccioli, M; Jetzer, P; Molinaro, R

    2010-01-01

    We discuss the colour, age and metallicity gradients in a wide sample of local SDSS early- and late-type galaxies. From the fitting of stellar population models we find that metallicity is the main driver of colour gradients and the age in the central regions is a dominant parameter which rules the scatter in both metallicity and age gradients. We find a consistency with independent observations and a set of simulations. From the comparison with simulations and theoretical considerations we are able to depict a general picture of a formation scenario.

  9. Gradient Yamabe Solitons on Warped Products

    OpenAIRE

    He, Chenxu

    2011-01-01

    The special nature of gradient Yamabe soliton equation which was first observed by Cao-Sun-Zhang\\cite{CaoSunZhang} shows that a complete gradient Yamabe soliton with non-constant potential function is either defined on the Euclidean space with rotational symmetry, or on the warped product of the real line with a manifold of constant scalar curvature. In this paper we consider the classification in the latter case. We show that a complete gradient steady Yamabe soliton on warped product is nec...

  10. Sound beam manipulation based on temperature gradients

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Feng [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); School of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Quan, Li; Liu, Xiaozhou, E-mail: xzliu@nju.edu.cn; Gong, Xiufen [Key Laboratory of Modern Acoustics, Institute of Acoustics and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China)

    2015-10-28

    Previous research with temperature gradients has shown the feasibility of controlling airborne sound propagation. Here, we present a temperature gradients based airborne sound manipulation schemes: a cylindrical acoustic omnidirectional absorber (AOA). The proposed AOA has high absorption performance which can almost completely absorb the incident wave. Geometric acoustics is used to obtain the refractive index distributions with different radii, which is then utilized to deduce the desired temperature gradients. Since resonant units are not applied in the scheme, its working bandwidth is expected to be broadband. The scheme is temperature-tuned and easy to realize, which is of potential interest to fields such as noise control or acoustic cloaking.

  11. Electrochemical deposition of mineralized BSA/collagen coating.

    Science.gov (United States)

    Zhuang, Junjun; Lin, Jun; Li, Juan; Wang, Huiming; Cheng, Kui; Weng, Wenjian

    2016-09-01

    In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170-0.173mg/cm(2), enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold).

  12. Thin Film Deposition of Conducting Polymers and Carbon Allotropes via Interfacial Solution Processing and Evaporative Vapor Phase Polymerization

    OpenAIRE

    D'Arcy, Julio Marcelo

    2012-01-01

    A new solution processing technique is developed for depositing continuously conductive transparent thin films comprised of conducting polymer nanostructures. The deposition mechanism is driven by interfacial surface tension gradients leading to rapid directional fluid flow known as the Marangoni effect. This technique is a universal solution to thin film deposition for coating any type of substrate at ambient conditions within seconds. The versatility of this method of deposition is further ...

  13. CMB Anisotropies from a Gradient Mode

    CERN Document Server

    Mirbabayi, Mehrdad

    2014-01-01

    A pure gradient mode must have no observable dynamical effect at linear level. We confirm this by showing that its contribution to the dipolar power asymmetry of CMB anisotropies vanishes, if Maldacena's consistency condition is satisfied. To this end, the existing second order Sachs-Wolfe formula in the squeezed limit is extended to include a gradient in the long mode and to account for the change in the location of the last scattering surface induced by this mode. At second order, a gradient mode generated in Single-field inflation is shown to induce a quadrupole moment. For instance in a matter-dominated model it is equal to 5/18 times the square of the linear gradient part. This quadrupole can be cancelled by superposing a quadratic perturbation. The result is shown to be a non-linear extension of Weinberg's adiabatic modes: a long-wavelength physical mode which looks locally like a coordinate transformation.

  14. Unimodal and crossmodal gradients of spatial attention

    DEFF Research Database (Denmark)

    Föcker, J.; Hötting, K.; Gondan, Matthias;

    2010-01-01

    Behavioral and event-related potential (ERP) studies have shown that spatial attention is gradually distributed around the center of the attentional focus. The present study compared uni- and crossmodal gradients of spatial attention to investigate whether the orienting of auditory and visual...... spatial attention is based on modality specific or supramodal representations of space. Auditory and visual stimuli were presented from five speaker locations positioned in the right hemifield. Participants had to attend to the innermost or outmost right position in order to detect either visual...... or auditory deviant stimuli. Detection rates and event-related potentials (ERPs) indicated that spatial attention is distributed as a gradient. Unimodal spatial ERP gradients correlated with the spatial resolution of the modality. Crossmodal spatial gradients were always broader than the corresponding...

  15. Vegetation patterns and environmental gradients in Benin

    NARCIS (Netherlands)

    Adomou, A.

    2005-01-01

    Key words: West Africa, Benin, vegetation patterns, floristic areas, phytogeography, chorology, floristic gradients, climatic factors, water availability, Dahomey Gap, threatened plants, biodiversity, conservation.Understanding plant species distribution patterns and the underlying factors is a cruc

  16. Artificial photosynthesis: Light-activated calcium gradients

    Science.gov (United States)

    Thompson, David H.

    2002-12-01

    Photosynthetic organisms use light to create chemical gradients across bilayer membranes that drive energetically unfavourable reactions. Synthetic systems that accomplish the same feat may find uses in a variety of biological and non-biological applications.

  17. The gradient flow in simple field theories

    CERN Document Server

    Monahan, Christopher

    2015-01-01

    The gradient flow is a valuable tool for the lattice community, with applications from scale-setting to implementing chiral fermions. Here I focus on the gradient flow as a means to suppress power-divergent mixing. Power-divergent mixing stems from the hypercubic symmetry of the lattice regulator and is a particular difficulty for calculations of, for example, high moments of parton distribution functions. The gradient flow removes power-divergent mixing on the lattice, provided the flow time is kept fixed in physical units, at the expense of introducing a new physical scale in the continuum. One approach to dealing with this new scale is the smeared operator product expansion, a formalism that systematically connects nonperturbative calculations of flowed operators to continuum physics. I study the role of the gradient flow in suppressing power-divergent mixing and present the first nonperturbative study in scalar field theory.

  18. Cholic acid is accumulated spontaneously, driven by membrane Delta pH, in many lactobacilli

    NARCIS (Netherlands)

    Kurdi, P; van Veen, HW; Tanaka, H; Mierau, [No Value; Konings, WN; Tannock, GW; Tomita, F; Yokota, A

    2000-01-01

    Many lactobacilli from various origins were found to apparently lack cholic acid extrusion activity. Cholic acid was accumulated spontaneously, driven by the transmembrane proton gradient. Accumulation is a newly identified kind of interaction between intestinal microbes and unconjugated bile acids

  19. Voltammetry under a Controlled Temperature Gradient

    OpenAIRE

    Jan Krejci, Jr.; Tomas Marvanek; Zuzana Sajdlova; Jan Krejci

    2010-01-01

    Electrochemical measurements are generally done under isothermal conditions. Here we report on the application of a controlled temperature gradient between the working electrode surface and the solution. Using electrochemical sensors prepared on ceramic materials with extremely high specific heat conductivity, the temperature gradient between the electrode and solution was applied here as a second driving force. This application of the Soret phenomenon increases the mass transfer in the Nerns...

  20. The gradient flow in a twisted box

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Alberto [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2013-08-15

    We study the perturbative behavior of the gradient flow in a twisted box. We apply this information to define a running coupling using the energy density of the flow field. We study the step-scaling function and the size of cutoff effects in SU(2) pure gauge theory. We conclude that the twisted gradient flow running coupling scheme is a valid strategy for step-scaling purposes due to the relatively mild cutoff effects and high precision.

  1. Nonlinear strain gradient elastic thin shallow shells

    OpenAIRE

    Lazopoulos, K.A.

    2011-01-01

    Abstract The governing equilibrium equations for strain gradient elastic thin shallow shells are derived, considering non-linear strains and linear constitutive strain gradient elastic relations. Adopting Kirchhoff's theory of thin shallow structures, the equilibrium equations, along with the boundary conditions, are formulated through a variational procedure. It turns out that new terms are introduced, indicating the importance of the cross-section area in bending of thin plates. ...

  2. Gradient-prolongation commutativity and graph theory

    OpenAIRE

    Musy, François; Nicolas, Laurent; Perrussel, Ronan

    2007-01-01

    6 pages International audience This Note gives conditions that must be imposed to algebraic multilevel discretizations involving at the same time nodal and edge elements so that a gradient-prolongation commutativity condition will be satisfied; this condition is very important, since it characterizes the gradients of coarse nodal functions in the coarse edge function space. They will be expressed using graph theory and they provide techniques to compute approximation bases at each level.

  3. The local power of the gradient test

    CERN Document Server

    Lemonte, Artur

    2010-01-01

    The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate $n^{-1/2}$, $n$ being the sample size. Comparisons of the local powers of the gradient, likelihood ratio, Wald and score tests reveal no uniform superiority property. The power performance of all four criteria in one-parameter exponential family is examined.

  4. Intratumoral oxygen gradients mediate sarcoma cell invasion.

    Science.gov (United States)

    Lewis, Daniel M; Park, Kyung Min; Tang, Vitor; Xu, Yu; Pak, Koreana; Eisinger-Mathason, T S Karin; Simon, M Celeste; Gerecht, Sharon

    2016-08-16

    Hypoxia is a critical factor in the progression and metastasis of many cancers, including soft tissue sarcomas. Frequently, oxygen (O2) gradients develop in tumors as they grow beyond their vascular supply, leading to heterogeneous areas of O2 depletion. Here, we report the impact of hypoxic O2 gradients on sarcoma cell invasion and migration. O2 gradient measurements showed that large sarcoma mouse tumors (>300 mm(3)) contain a severely hypoxic core [≤0.1% partial pressure of O2 (pO2)] whereas smaller tumors possessed hypoxic gradients throughout the tumor mass (0.1-6% pO2). To analyze tumor invasion, we used O2-controllable hydrogels to recreate the physiopathological O2 levels in vitro. Small tumor grafts encapsulated in the hydrogels revealed increased invasion that was both faster and extended over a longer distance in the hypoxic hydrogels compared with nonhypoxic hydrogels. To model the effect of the O2 gradient accurately, we examined individual sarcoma cells embedded in the O2-controllable hydrogel. We observed that hypoxic gradients guide sarcoma cell motility and matrix remodeling through hypoxia-inducible factor-1α (HIF-1α) activation. We further found that in the hypoxic gradient, individual cells migrate more quickly, across longer distances, and in the direction of increasing O2 tension. Treatment with minoxidil, an inhibitor of hypoxia-induced sarcoma metastasis, abrogated cell migration and matrix remodeling in the hypoxic gradient. Overall, we show that O2 acts as a 3D physicotactic agent during sarcoma tumor invasion and propose the O2-controllable hydrogels as a predictive system to study early stages of the metastatic process and therapeutic targets. PMID:27486245

  5. ONLINE REGULARIZED GENERALIZED GRADIENT CLASSIFICATION ALGORITHMS

    Institute of Scientific and Technical Information of China (English)

    Leilei Zhang; Baohui Sheng; Jianli Wang

    2010-01-01

    This paper considers online classification learning algorithms for regularized classification schemes with generalized gradient.A novel capacity independent approach is presented.It verifies the strong convergence of sizes and yields satisfactory convergence rates for polynomially decaying step sizes.Compared with the gradient schemes,this al-gorithm needs only less additional assumptions on the loss function and derives a stronger result with respect to the choice of step sizes and the regularization parameters.

  6. Design of spherical symmetric gradient index lenses

    OpenAIRE

    Miñano Dominguez, Juan Carlos; Grabovičkić, Dejan; Benitez Gimenez, Pablo; Gonzalez Lopez, Juan Carlos; Santamaria Galdon, Maria Asuncion

    2012-01-01

    Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, ...

  7. Cellular Sensing Ability in Spatial Gradients Environment

    CERN Document Server

    Liou, Shu-Hao

    2011-01-01

    Many eukaryotic and prokaruotic cells can exhibit remarkable sensing ability under tiny gradient of chemical compound. Here we consider the completely grand partition function with ligands and receptors and demonstrate the minimum asymptotic variances to show the ability. These results avoid the inconsistencies from other studies. Moreover, we show the gradient steepness is more important element in sensing ability than local concentration, and our results are corresponding with other experiment results.

  8. Proton gradients in intact cyanobacteria

    Science.gov (United States)

    Belkin, S.; Mehlhorn, R. J.; Packer, L.

    1987-01-01

    The internal pH values of two unicellular cyanobacterial strains were determined with electron spin resonance probes, over an external pH range of 6 to 9, in the light and in the dark. The slow growing, thylakoid-lacking Gloeobacter violaceus was found to have a low capacity for maintaining a constant internal pH. The distribution pattern of weak acid and amine nitroxide spin probes across the cell membranes of this organism, in the light and in the dark, was consistent with the assumption that it contains a single intracellular compartment. At an external pH of 7.0, intracellular pH was 6.8 in the dark and 7.2 in the light. The cells of Agmenellum quadruplicatum, a marine species, were found to contain two separate compartments; in the dark, the pH of the cytoplasmic and the intrathylakoid spaces were calculated to be 7.2 and 5.5, respectively. Upon illumination, the former increased and the latter decreased by about 0.5 pH units.

  9. Liquid-phase-deposited barium titanate thin films on silicon

    International Nuclear Information System (INIS)

    Using a mixture of hexafluorotitanic acid, barium nitrate and boric acid, high refractive index (1.54) barium titanate films can be deposited on silicon substrates. The deposited barium titanate films have featureless surfaces. The deposition temperature is near room temperature (800C). However, there are many fluorine and silicon incorporations in the films. The refractive index of the as-deposited film is 1.54. By current-voltage measurement, the leakage current of the as-deposited film with a thickness of 1000 A is about 9.48x10-7 A cm-2 at the electrical field intensity of 0.3 MV cm-1. By capacitance-voltage measurement, the effective oxide charge of the liquid-phase-deposited barium titanate film is 3.06x1011 cm-2 and the static dielectric constant is about 22. (author)

  10. Gradient-based compressive image fusion

    Institute of Scientific and Technical Information of China (English)

    Yang CHEN‡; Zheng QIN

    2015-01-01

    We present a novel image fusion scheme based on gradient and scrambled block Hadamard ensemble (SBHE) sam-pling for compressive sensing imaging. First, source images are compressed by compressive sensing, to facilitate the transmission of the sensor. In the fusion phase, the image gradient is calculated to reflect the abundance of its contour information. By com-positing the gradient of each image, gradient-based weights are obtained, with which compressive sensing coefficients are achieved. Finally, inverse transformation is applied to the coefficients derived from fusion, and the fused image is obtained. Information entropy (IE), Xydeas’s and Piella’s metrics are applied as non-reference objective metrics to evaluate the fusion quality in line with different fusion schemes. In addition, different image fusion application scenarios are applied to explore the scenario adaptability of the proposed scheme. Simulation results demonstrate that the gradient-based scheme has the best per-formance, in terms of both subjective judgment and objective metrics. Furthermore, the gradient-based fusion scheme proposed in this paper can be applied in different fusion scenarios.

  11. Pressure gradient influence in turbulent boundary layers

    Science.gov (United States)

    Reuther, Nico; Kaehler, Christian J.

    2015-11-01

    Understanding wall-bounded turbulence is still an ongoing process. Although remarkable progress has been made in the last decades, many challenges still remain. Mean flow statistics are well understood in case of zero pressure gradient flows. However, almost all turbulent boundary layers in technical applications, such as aircrafts, are subjected to a streamwise pressure gradient. When subjecting turbulent boundary layers to adverse pressure gradients, significant changes in the statistical behavior of the near-wall flow have been observed in experimental studies conducted however the details dynamics and characteristics of these flows has not been fully resolved. The sensitivity to Reynolds number and the dependency on several parameters, including the dependence on the pressure gradient parameter, is still under debate and very little information exists about statistically averaged quantities such as the mean velocity profile or Reynolds stresses. In order to improve the understanding of wall-bounded turbulence, this work experimentally investigates turbulent boundary layer subjected to favorable and adverse pressure gradients by means of Particle Image Velocimetry over a wide range of Reynolds numbers, 4200 statistics was found to increase significantly for a flow subjected to an adverse pressure gradient.

  12. Airfoil deposition model

    Science.gov (United States)

    Kohl, F. J.

    1982-01-01

    The methodology to predict deposit evolution (deposition rate and subsequent flow of liquid deposits) as a function of fuel and air impurity content and relevant aerodynamic parameters for turbine airfoils is developed in this research. The spectrum of deposition conditions encountered in gas turbine operations includes the mechanisms of vapor deposition, small particle deposition with thermophoresis, and larger particle deposition with inertial effects. The focus is on using a simplified version of the comprehensive multicomponent vapor diffusion formalism to make deposition predictions for: (1) simple geometry collectors; and (2) gas turbine blade shapes, including both developing laminar and turbulent boundary layers. For the gas turbine blade the insights developed in previous programs are being combined with heat and mass transfer coefficient calculations using the STAN 5 boundary layer code to predict vapor deposition rates and corresponding liquid layer thicknesses on turbine blades. A computer program is being written which utilizes the local values of the calculated deposition rate and skin friction to calculate the increment in liquid condensate layer growth along a collector surface.

  13. Gradient SiNx IBAD coating: preparation and measurement of concentration profile

    International Nuclear Information System (INIS)

    Preparation of gradient SiNx coating by the ion beam assisted deposition method with high ion energy is described. Special shape of the concentration of nitrogen in the coating was chosen and constructed. Concentration profile was constructed in three steps with different ratios of nitrogen and silicon atom fluxes. Ion energy was 90 keV. Concentration profile was measured by RBS (Rutherford Back Scattering) method. (author). 1 ref., 2 figs

  14. Geophysical exploration of disseminated and stockwork deposits associated with plutonic intrusive rock: a case study on the eastern flank of Colombia’s western cordillera

    Directory of Open Access Journals (Sweden)

    Hernández Pardo Orlando

    2012-10-01

    Full Text Available

    Disseminated deposits are low-grade, large tonnage deposits which are mainly mined for gold, copper, molybdenum and tin. These deposits are normally associated with intermediate to acid plutonic intrusive rocks and all are characterized by intense, extensive hydrothermal alteration of host rocks. Disseminated deposit exploration in the tropics suffers from difficult geological mapping due to dense vegetation, lack of rock outcrops and extensive but variable saprolytic weathering. Geophysical exploration of these deposits normally includes magnetic, induced polarization and gamma ray spectrometry surveys. The largest RTP total magnetic field anomaly highs are usually associated with diorite porphyry intrusive bodies. Diorites are usually less magnetic than basaltic rocks; thus when magnetic anomaly highs are related to intrusions they can be explained by basic metals’ intensive mineralization (including magnetite associated with porphyry intrusions. Magnetic anomaly gradients regularly help delineate local discontinuities which can be interpreted as local faults and joints that can be mineralized. Gamma ray spectrometry is useful for determining anomalous potassium, uranium and thorium concentration as it can map alteration halos and linear discontinuities. Statistical analysis of the data also can determine the intermediate intrusive / extrusive nature of porphyry intrusions. Gamma ray spectrometry can help to determine elemental potassium concentration, regardless of the associated potassium mineral species, thereby enabling alteration mapping in a geological setting related to volcanic-associated massive sulphide base metal and gold deposits. An induced polarization survey is useful in outlining disseminated sulphide distribution in porphyry deposits related to chargeability anomaly highs. The results of the Quinchía project’s geophysical exploration program are discussed.

  15. Coronal Heating Driven by Magnetic-gradient Pumping Mechanism in Solar Plasmas

    CERN Document Server

    Tan, Baolin

    2014-01-01

    The solar coronal heating is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with considerable magnetic gradient from solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism and try to explain the formation of hot plasma upflows, such as the hot type II spicules and hot plasma ejections, etc. In MGP mechanism, the magnetic gradients drive the energetic particles to move upwards from the underlying solar atmosphere and form hot upflows. These upflow energetic particles deposit in corona and make it becoming very hot. Roughly estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km/s in chromosphere and about 130 km/s in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them and deposit in the corona. The deposition of energetic particles will make the corona become...

  16. Coronal heating driven by a magnetic gradient pumping mechanism in solar plasmas

    International Nuclear Information System (INIS)

    The heating of the solar corona is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with a considerable magnetic gradient from the solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism to try to explain the formation of hot plasma upflows, such as hot type II spicules and hot plasma ejections. In the MGP mechanism, the magnetic gradient may drive the energetic particles to move upward from the underlying solar atmosphere and form hot upflows. These upflow energetic particles are deposited in the corona, causing it to become very hot. Rough estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km s–1 in the chromosphere and about 130 km s–1 in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them, and deposit them in the corona. The deposit of these energetic particles causes the corona to become hot, and the escape of such particles from the photosphere leaves it a bit cold. This mechanism can present a natural explanation to the mystery of solar coronal heating.

  17. Irreducible decomposition of strain gradient tensor in isotropic strain gradient elasticity

    CERN Document Server

    Lazar, Markus

    2016-01-01

    In isotropic strain gradient elasticity, we decompose the strain gradient tensor into its irreducible pieces under the n-dimensional orthogonal group O(n). Using the Young tableau method for traceless tensors, four irreducible pieces (n>2), which are canonical, are obtained. In three dimensions, the strain gradient tensor can be decomposed into four irreducible pieces with 7+5+3+3 independent components whereas in two dimensions, the strain gradient tensor can be decomposed into three irreducible pieces with 2+2+2 independent components. The knowledge of these irreducible pieces is extremely useful when setting up constitutive relations and strain energy.

  18. Improving the accuracy of pulsed field gradient NMR diffusion experiments: Correction for gradient non-uniformity

    Science.gov (United States)

    Connell, Mark A.; Bowyer, Paul J.; Adam Bone, P.; Davis, Adrian L.; Swanson, Alistair G.; Nilsson, Mathias; Morris, Gareth A.

    2009-05-01

    Pulsed field gradient NMR is a well-established technique for the determination of self-diffusion coefficients. However, a significant source of systematic error exists in the spatial variation of the applied pulsed field gradient. Non-uniform pulsed field gradients cause the decay of peak amplitudes to deviate from the expected exponential dependence on gradient squared. This has two undesirable effects: the apparent diffusion coefficient will deviate from the true value to an extent determined by the choice of experimental parameters, and the error estimated by the nonlinear least squares fitting will contain a significant systematic contribution. In particular, the apparent diffusion coefficient determined by exponential fitting of the diffusional attenuation of NMR signals will depend both on the exact pulse widths used and on the range of gradient amplitudes chosen. These problems can be partially compensated for if experimental attenuation data are fitted to a function corrected for the measured spatial dependence of the gradient and signal strength. This study describes a general alternative to existing methods for the calibration of NMR diffusion measurements. The dominant longitudinal variation of the pulsed field gradient amplitude and the signal strength are mapped by measuring pulsed field gradient echoes in the presence of a weak read gradient. These data are then used to construct a predicted signal decay function for the whole sample, which is parameterised as the exponential of a power series. Results are presented which compare diffusion coefficients obtained using the new calibration method with previous literature values.

  19. Oxygen reduction in acid media: influence of the activity of CoNPc(1,2) bilayer deposits in relation to their attachment to the carbon black support and role of surface groups as a function of heat treatment

    NARCIS (Netherlands)

    Biloul, A.; Contamin, O.; Scarbeck, G.; Savy, M.; Palys, B.J.; Riga, J.; Verbist, J.

    1994-01-01

    O2 reduction was investigated using rotating disk electrode and voltammetry techniques on NPcCo(1,2) impregnations deposited onto two kinds of carbon black support. They were selected on the basis of their similar pH and dibuthylphthalate (DBP) adsorption values. Samples were also characterized by I

  20. Factors influencing chloride deposition in a coastal hilly area and application to chloride deposition mapping

    Directory of Open Access Journals (Sweden)

    H. Guan

    2009-09-01

    Full Text Available Chloride is commonly used as an environmental tracer for studying water flow and solute transport in the environment. It is especially useful for estimating groundwater recharge based on the commonly used chloride mass balance (CMB method. Strong spatial variability in chloride deposition in coastal areas is one difficulty encountered in appropriately applying the CMB approach. Furthermore, intensive vegetation clearance for agriculture, for example during the European settlement in many coastal areas of Australia, may have perturbed catchment chloride balance conditions for appropriate use in CMB applications. In order to deal with these issues, a high resolution chloride deposition map in the coastal region is needed. In this study, we examined geographic, orographic, and atmospheric factors influencing chloride deposition in the Mount Lofty Ranges (MLR, a coastal hilly area of approximately 9000 km2 spatial extent in South Australia, using partial correlation and regression analyses. The results indicate that coastal distance, and terrain aspect and slope are two most significant factors controlling chloride deposition. Coastal distance accounts for 65% spatial variability in chloride deposition, with terrain aspect and slope for 8%. The deposition gradient is about 0.08 gm-2 year-1 km-1 as one progresses inland. The results are incorporated into a published de-trended residual kriging approach (ASOADeK to produce a 1 km×1 km resolution annual chloride deposition map and a bulk precipitation chloride concentration map. The average uncertainty of the deposition map is about 30% in the western MLR, and over 50% in the eastern MLR. The maps will form a very useful basis for examining catchment chloride balances for use in the CMB application in the study area.

  1. Constrained length minimum inductance gradient coil design.

    Science.gov (United States)

    Chronik, B A; Rutt, B K

    1998-02-01

    A gradient coil design algorithm capable of controlling the position of the homogeneous region of interest (ROI) with respect to the current-carrying wires is required for many advanced imaging and spectroscopy applications. A modified minimum inductance target field method that allows the placement of a set of constraints on the final current density is presented. This constrained current minimum inductance method is derived in the context of previous target field methods. Complete details are shown and all equations required for implementation of the algorithm are given. The method has been implemented on computer and applied to the design of both a 1:1 aspect ratio (length:diameter) central ROI and a 2:1 aspect ratio edge ROI gradient coil. The 1:1 design demonstrates that a general analytic method can be used to easily obtain very short gradient coil designs for use with specialized magnet systems. The edge gradient design demonstrates that designs that allow imaging of the neck region with a head sized gradient coil can be obtained, as well as other applications requiring edge-of-cylinder regions of uniformity.

  2. Gradient-enhanced FAWSETS perfusion measurements

    Science.gov (United States)

    Marro, Kenneth I.; Lee, Donghoon; Hyyti, Outi M.

    2005-08-01

    This work describes the use of custom-built gradients to enhance skeletal muscle perfusion measurements acquired with a previously described arterial spin labeling technique known as FAWSETS (flow-driven arterial water stimulation with elimination of tissue signal). Custom-built gradients provide active control of the static magnetic field gradient on which FAWSETS relies for labeling. This allows selective, 180° modulations of the phase of the perfusion component of the signal. Phase cycling can then be implemented to eliminate all extraneous components leaving a signal that exclusively reflects capillary-level perfusion. Gradient-enhancement substantially reduces acquisition time and eliminates the need to acquire an ischemic signal to quantify perfusion. This removes critical obstacles to application of FAWSETS in organs other than skeletal muscle and makes the measurements more desirable for clinical environments. The basic physical principles of gradient-enhancement are demonstrated in flow phantom experiments and in vivo utility is demonstrated in rat hind limb during stimulated exercise.

  3. Modeling of the performance of a cryogenic gas cooled Yb:YAG multislab amplifier with a longitudinal doping gradient concentration

    Science.gov (United States)

    Xiao, Kaibo; Yuan, Xiaodong; Yan, Xiongwei; Li, Min; Jiang, Xinying; Wang, Zhenguo; Li, Mingzhong; Zheng, Wanguo; Zheng, Jiangang

    2016-04-01

    A cryogenic helium gas cooled Yb:YAG multislab amplifier with a longitudinal doping gradient concentration was proposed for developing high energy, high average power laser systems. As a comparison, the performance of the gradient doped amplifier was investigated with other constant and stepped doped amplifiers in terms of energy storage capacity, heat deposition, and amplification, based on the theory of quasi-three-level laser ions, Monte Carlo, and ray-tracing approaches. Improved lasing characteristics with more homogenous distributions of gain and heat load and higher efficiency was achieved in the gradient doped multislab amplifier while lower gain medium volume was required. It is shown that at the optimum operating temperature of 200 K, the maximum output energy of 867.76 J in the gradient doped amplifier was obtained, corresponding to an optical-to-optical efficiency of 22.41%.

  4. Deposition patterns with Turbuhaler.

    Science.gov (United States)

    Borgström, L

    1994-01-01

    The degree of lung deposition is an important factor in the evaluation of different inhalation flow driven dry powder inhalers. A number of studies using radioactive and non-radioactive methods have been performed with Turbuhaler to assess lung deposition under different conditions. Mean total lung deposition of terbutaline sulfate or budesonide via Turbuhaler in healthy volunteers ranged from 21-32% of the dose when a normal inhalation flow (60L/min) was used. At a low flow (30L/min) a mean 15% of the dose was deposited in the lungs, a similar value as for a well-performed inhalation via a pressurized metered dose inhaler. Regional deposition of inhaled drug can be expressed as the ratio between the amount of drug deposited in the more peripheral parts of the lung relative to the more central parts. In a comparative study, budesonide and terbutaline sulfate were given by inhalation via Turbuhaler to healthy volunteers. The ratio of peripheral to central deposition was 2.03 for terbutaline and 1.72 for budesonide. Thus, both the water-soluble terbutaline sulfate and the non-water soluble budesonide seemed to behave in the same way when inhaled via Turbuhaler. In conclusion, Turbuhaler delivers over 20% of a metered dose to the lungs when inhaled at a normal inhalation flow rate. The regional deposition pattern in the lungs was the same for terbutaline sulfate and budesonide, in spite of differences in water solubility. PMID:10147081

  5. MAPLE deposition of nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P., E-mail: annapaola.caricato@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Arima, V.; Catalano, M. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Cesaria, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Cozzoli, P.D. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Martino, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Taurino, A.; Rella, R. [Institute for Microelectronics and Microsystems, IMM-CNR, Via Monteroni, I-73100 Lecce (Italy); Scarfiello, R. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Tunno, T. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Zacheo, A. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy)

    2014-05-01

    The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

  6. Operational mapping of atmospheric nitrogen deposition to the Baltic Sea

    Directory of Open Access Journals (Sweden)

    O. Hertel

    2003-01-01

    Full Text Available A new model system for mapping and forecasting nitrogen deposition to the Baltic Sea has been developed. The system is based on the Lagrangian variable scale transport-chemistry model ACDEP (Atmospheric Chemistry and Deposition model, and aims at delivering deposition estimates to be used as input to marine ecosystem models. The system is tested by comparison of model results to measurements from monitoring stations around the Baltic Sea. The comparison shows that observed annual mean ambient air concentrations and wet depositions are well reproduced by the model. Diurnal mean concentrations of NHx (sum of NH3 and NH4+ and NO2 are fairly well reproduced, whereas concentrations of total nitrate (sum of HNO3 and NO3- are somewhat overestimated. Wet depositions of nitrate and ammonia are fairly well described for annual mean values, whereas the discrepancy is high for the monthly mean values and the wet depositions are rather poorly described concerning the diurnal mean values. The model calculations show that the annual atmospheric nitrogen deposition has a pronounced south--north gradient with depositions in the range about 1.0 T N km-2 in the south and 0.2 T N km-2 in the north. The results show that in 1999 the maximum diurnal mean deposition to the Danish waters appeared during the summer in the algae growth season. For the northern parts of the Baltic the highest depositions were distributed over most of the year. Total deposition to the Baltic Sea was for the year 1999 estimated to 318 kT N for an area of 464 406 km2 equivalent to an average deposition of 684 kg N/km2.

  7. Adaptive Thermostats for Noisy Gradient Systems

    CERN Document Server

    Leimkuhler, Benedict

    2015-01-01

    We study numerical methods for sampling probability measures in high dimensions where the underlying model is only approximately identified with a gradient system. Extended stochastic dynamical methods are discussed which have application to multiscale models, nonequilibrium molecular dynamics and Bayesian sampling techniques arising in emerging machine learning applications. In addition to providing a more comprehensive discussion of the foundations of these methods, we propose a new numerical method for the Adaptive Langevin/stochastic gradient Nos\\'e-Hoover thermostat that achieves a dramatic improvement in numerical efficiency over the most popular stochastic gradient methods reported in the literature. We also demonstrate that the newly-established method inherits a superconvergence property (fourth order convergence to the invariant measure for configurational quantities) recently demonstrated in the setting of Langevin dynamics. Our findings are verified by numerical experiments.

  8. Dynamics of gradient formation by intracellular shuttling

    Energy Technology Data Exchange (ETDEWEB)

    Berezhkovskii, Alexander M. [Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892 (United States); Shvartsman, Stanislav Y. [Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-08-21

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  9. Time Rate Gradient Effects and Negative Mass

    Science.gov (United States)

    Miksch, Edmond

    2008-03-01

    The Harvard tower Experiment and tests with accurate atomic clocks show that a clock at a high elevation indicates more elapsed time than a clock at a low elevation, both clocks properly measuring time at their locations. This fact mandates that Newton's first law of motion be rewritten to cite impulse balance rather than force balance. Time rate gradient effects explain how the weight of a precisely vertical and precisely uniform electric field or a precisely vertical and precisely uniform magnetic field is supported in a precisely unidirectional gravitational field. Time rate gradient effects also explain how the weight of a unidirectional gravitational field is reacted. It is confirmed that the mass density of the gravitational field is negative. http://www.TimeRateGradient.com; http://www.Negative-Mass.com; http://www.EinsteinsElevator.com

  10. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel;

    2015-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...... and reproducible guideline for sampling along gradients in all fields of ecology and science in general. 2. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric...... unimodal). In the simulations we accounted for different levels of random and systematic error, the two sources of noise in ecological data. We quantified prediction success for varying total sample size, number of locations sampled along a spatial/temporal gradient and number of replicates per sampled...

  11. Gradient expansion, curvature perturbations and magnetized plasmas

    CERN Document Server

    Giovannini, Massimo

    2011-01-01

    The properties of magnetized plasmas are always investigated under the hypothesis that the relativistic inhomogeneities stemming from the fluid sources and from the geometry itself are sufficiently small to allow for a perturbative description prior to photon decoupling. The latter assumption is hereby relaxed and pre-decoupling plasmas are described within a suitable expansion where the inhomogeneities are treated to a given order in the spatial gradients. It is argued that the (general relativistic) gradient expansion shares the same features of the drift approximation, customarily employed in the description of cold plasmas, so that the two schemes are physically complementary in the large-scale limit and for the low-frequency branch of the spectrum of plasma modes. The two-fluid description, as well as the magnetohydrodynamical reduction, are derived and studied in the presence of the spatial gradients of the geometry. Various solutions of the coupled system of evolution equations in the anti-Newtonian re...

  12. Vertical gradients of sunspot magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hagyard, M.J.; Teuber, D.; West, E.A.; Tandberg-Hanssen, E.; Henze, W. Jr.; Beckers, J.M.

    1983-04-01

    The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.

  13. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are...... investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... predictions. These differences increase significantly when large strains are taken into account, as a consequence of the contribution of strain gradients to the work hardening of the material. The magnitude of stress elevation at the crack tip and the distance ahead of the crack where GNDs significantly alter...

  14. Substrate Curvature Gradient Drives Rapid Droplet Motion

    Science.gov (United States)

    Lv, Cunjing; Chen, Chao; Chuang, Yin-Chuan; Tseng, Fan-Gang; Yin, Yajun; Grey, Francois; Zheng, Quanshui

    2014-07-01

    Making small liquid droplets move spontaneously on solid surfaces is a key challenge in lab-on-chip and heat exchanger technologies. Here, we report that a substrate curvature gradient can accelerate micro- and nanodroplets to high speeds on both hydrophilic and hydrophobic substrates. Experiments for microscale water droplets on tapered surfaces show a maximum speed of 0.42 m/s, 2 orders of magnitude higher than with a wettability gradient. We show that the total free energy and driving force exerted on a droplet are determined by the substrate curvature and substrate curvature gradient, respectively. Using molecular dynamics simulations, we predict nanoscale droplets moving spontaneously at over 100 m/s on tapered surfaces.

  15. Collective chemotaxis through noisy multicellular gradient sensing

    CERN Document Server

    Varennes, Julien; Mugler, Andrew

    2016-01-01

    Collective cell migration in response to a chemical cue occurs in many biological processes such as morphogenesis and cancer metastasis. Clusters of migratory cells in these systems are capable of responding to gradients of less than 1% difference in chemical concentration across a cell length. Multicellular systems are extremely sensitive to their environment and while the limits to multicellular sensing are becoming known, how this information leads to coherent migration remains poorly understood. We develop a computational model of multicellular sensing and migration in which groups of cells collectively measure noisy chemical gradients. The output of the sensing process is coupled to individual cells polarization to model migratory behavior. Through the use of numerical simulations, we find that larger clusters of cells detect the gradient direction with higher precision and thus achieve stronger polarization bias, but larger clusters also induce more drag on collective motion. The trade-off between these...

  16. Conjugate gradient algorithms using multiple recursions

    Energy Technology Data Exchange (ETDEWEB)

    Barth, T.; Manteuffel, T.

    1996-12-31

    Much is already known about when a conjugate gradient method can be implemented with short recursions for the direction vectors. The work done in 1984 by Faber and Manteuffel gave necessary and sufficient conditions on the iteration matrix A, in order for a conjugate gradient method to be implemented with a single recursion of a certain form. However, this form does not take into account all possible recursions. This became evident when Jagels and Reichel used an algorithm of Gragg for unitary matrices to demonstrate that the class of matrices for which a practical conjugate gradient algorithm exists can be extended to include unitary and shifted unitary matrices. The implementation uses short double recursions for the direction vectors. This motivates the study of multiple recursion algorithms.

  17. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  18. In vitro comparison of Doppler and catheter-measured pressure gradients in 3D models of mitral valve calcification.

    Science.gov (United States)

    Herrmann, Tarrah A; Siefert, Andrew W; Pressman, Gregg S; Gollin, Hannah R; Touchton, Steven A; Saikrishnan, Neelakantan; Yoganathan, Ajit P

    2013-09-01

    Mitral annular calcification (MAC) involves calcium deposition in the fibrous annulus supporting the mitral valve (MV). When calcification extends onto the leaflets, valve opening can be restricted. The influence of MAC MV geometry on Doppler gradients is unknown. This study describes a novel methodology to rapid-prototype subject-specific MAC MVs. Replicated valves were used to assess the effects of distorted annular-leaflet geometry on Doppler-derived, transmitral gradients in comparison to direct pressure measurements and to determine if transmitral gradients vary according to measurement location. Three-dimensional echocardiography data sets were selected for two MAC MVs and one healthy MV. These MVs were segmented and rapid prototyped in their middiastolic configuration for in vitro testing. The effects of MV geometry, measurement modality, and measurement location on transmitral pressure gradient were assessed by Doppler and catheter at three locations along the MV's intercommissural axis. When comparing dimensions of the rapid-prototyped valves to the subject echocardiography data sets, mean relative errors ranged from 6.2% to 35%. For the evaluated MVs, Doppler pressure gradients exhibited good agreement with catheter-measured gradients at a variety of flow rates, though with slight systematic overestimation in the recreated MAC valves. For all of the tested MVs, measuring the transmitral pressure gradient at differing valve orifice positions had minimal impact on observed gradients. Upon the testing of additional normal and calcific MVs, these data may contribute to an improved clinical understanding of MAC-related mitral stenosis. Moreover, they provide the ability to statistically evaluate between measurement locations, flow rates, and valve geometries for Doppler-derived pressure gradients. Determining these end points will contribute to greater clinical understanding for the diagnosis MAC patients and understanding the use and application of Doppler

  19. Design of spherical symmetric gradient index lenses

    Science.gov (United States)

    Miñano, Juan C.; Grabovičkić, Dejan; Benítez, Pablo; González, Juan C.; Santamaría, Asunción

    2012-10-01

    Spherical symmetric refractive index distributions also known as Gradient Index lenses such as the Maxwell-Fish-Eye (MFE), the Luneburg or the Eaton lenses have always played an important role in Optics. The recent development of the technique called Transformation Optics has renewed the interest in these gradient index lenses. For instance, Perfect Imaging within the Wave Optics framework has recently been proved using the MFE distribution. We review here the design problem of these lenses, classify them in two groups (Luneburg moveable-limits and fixed-limits type), and establish a new design techniques for each type of problem.

  20. Multiplicative Noise Removal using Gradient and Laplacian

    Institute of Scientific and Technical Information of China (English)

    He Lei Pan Zhen-kuan

    2009-01-01

    The variational methods for nmltiplicative noise removal have been received considerable attention in recent years.The traditional models based only on gradient result in staircase effect usually.So a hybrid high-order model based on gradient and Laphcian is proposed for mulfiplicative denoising.In order to avoid the shortcomings of explicit scheme in stability,the Gauss-seidel semi-implicit scheme is adopted.Experiments show that the proposed model can avoid staircase effect during removing multiplicative noise while preserving or enhancing edges.