Deposition

This study deals with the description of the vertical distribution of radiocaesium ( 137 Cs and 134 Cs) in a representative coniferous forest soil, investigated 10 months after the Fukushima radioactive fallout. During soil sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol þ Of) holds 52% (5.3 kBq m À2 ) of the Fukushima-derived and 25% (0.7 kBq m À2 ) of the pre-Fukushima 137 Cs at the time of the soil sampling. Including the pre-Fukushima 137 Cs, 99% of the total soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushimaderived 137 Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble 137 Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived 137 Cs was somewhat rapid.

The OECD guideline for studies on percutaneous penetration to be used in hazard and risk evaluations prescribes experimental conditions with optimal barrier integrity of the skin, which in many occupational settings probably is not true. Thus, workers may have compromised skin due to chemical or mechanical damage, due to different medical conditions (eczema, dermatitis, skin irritation) or related to occupational scenarios involving prolonged wet work. The present study used the OECD guideline procedures to study the in vitro percutaneous penetration through human skin of a number of model substances (glyphosat, caffeine, benzoic acid, malathion) covering a range of solubilities. Further, we studied the extent to which a slightly damaged skin would change the rate, the amount absorbed during dermal exposure and the distribution of chemical deposition between epidermis and dermis. The present study demonstrates that a limited damage to the skin significantly increases the permeability coefficient (K p) as well as total percutaneous penetration of chemicals, and most significantly for those compounds that due to their physicochemical characteristics (the most hydrophilic as well as the most lipophilic) have low penetration rates through intact skin. The present experiment not only confirms the proportionality between lipophilicity and potential for percutaneous penetration, but also illustrates that at a certain degree of lipophilicity of a model compound, the different skin compartments become more attractive for temporary deposition of model compounds. Moreover, a clear change from epidermal deposition towards a dominating dermis deposition of chemicals temporarily deposited within the skin is seen following damage to the skin barrier. Thus, the distribution of chemicals within the skin compartments is affected by the physicochemical characteristics of the chemicals as well as by the integrity of the skin. This observation may have implications when evaluating the possibility of removing chemicals from the skin through different cleansing procedures following unintended dermal exposures.

Fluvial erosion of peat deposits occurs in many environmental settings; however, the erosion and transport of large peat blocks by river channels has received relatively little attention. This paper describes the sedimentary significance and potential palaeoenvironmental interpretation of peat blocks in alluvial river systems. Evidence is presented from a number of field studies of upland river systems in northern England that illustrate a range of peat block forms and sedimentary features that are briefly compared with examples of peat blocks preserved in gravel stratigraphy. We show that peat blocks are an important geomorphological and sedimentological component of upland rivers draining eroding peatland catchments. They are of widespread occurrence and contribute significantly to river channel roughness and channel sedimentation. A variety of common sedimentary features can be observed including, shadow, crescent, perched, armoured, drape, embedded (part buried), cluster, and step forms. Peat blocks tend to be deposited on channel margins and bar tops and can be used as "maximum" stage indicator for major floods. The role of peat blocks in controlling sedimentation varies with channel width. In narrow channels where the size of the peat block approximates the channel width, blocks become jammed in the channel and exert a primary control on channel sedimentation. In wider channels, blocks tend to occur in isolation or in small clusters and are of only secondary importance in controlling sedimentation. Residence times of peat blocks varies from short periods of temporary deposition (days to months) to much longer timescales (months to years) with some blocks becoming permanently incorporated into the sedimentary record. The sedimentary characteristics of contemporary buried peat blocks have much in common with blocks preserved in alluvial gravel stratigraphy. This offers the potential for using these features for palaeoenvironmental reconstruction. Peat blocks in many ways are analogous to other low density geological materials (ice blocks, woody debris, and some volcanic sediments), and recognising the special sedimentological characteristics of this suite of materials is important as they are not always adequately characterised using conventional hydraulic relationships.

Wheat germ agglutinin (WGA) lectin is a model compound for the interaction between viruses and cells during infection events and thus an interesting analyte for mass-sensitive sensing to study these interaction phenomena. Scanning tunneling microscopy studies reveal that surface molecular imprinting leads to cavities having the dimensions of WGA dimers. These reincorporate WGA from phosphatebuffered saline between 1 and 160 μg/ml. Whereas the quartz crystal microbalance (QCM) frequency for molecularly imprinted polymer (MIP)-coated electrodes decreases, indicating uptake of the analyte, their nonimprinted counterparts yield positive, concentration-dependent frequency shifts characteristic for slip of the analyte on the QCM surface. The MIPs achieve selectivity factors towards bovine serum albumin of roughly 4 at higher protein concentrations. Brunauer-Emmett-Teller analysis reveals that binding is favored by 29 kJ/mol until the adsorption of up to ten monolayers on the MIP, whereas above this range the value is lower. Together with the binding behavior of MIP and nonimprinted polymers, this indicates that the MIP acts as a nucleus for multilayer deposition onto the surface.

Two aspects critical to the fracture behavior of three-wire stainless steel cladding were investigated by the Heavy-Section Steel Technology (HSST) Program: (1) radiation effects on cladding strength and toughness, and (2) the response of mechanically loaded, flawed structures in the presence of cladding (clad plate experiments).

Arrangements of cationic starches hydrophobized by acetylation (CS-acet) deposited from aqueous electrolyte solutions onto hydrophilized and hydrophobized silica surfaces were investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The influence of electrolyte composition, acetylation degree of cationic starch (DS ACET ), and deposition method was examined. On a hydrophobic substrate, CS-acet formed an open film with structure strongly dependent on DS ACET and electrolyte composition of the solution. On a hydrophilic substrate, acetylation increased the hydrophobicity of the film when the starch was deposited by adsorbing. When deposition was made by spin coating, i.e., the CS-acet was forced onto the substrate, the hydrophobic tuning by acetylation was lost. The films deposited by spin coating were thicker and considerably rougher than those deposited by adsorbing.

h i g h l i g h t s " The neurotoxins BMAA and DAB are deposited in Lesser Flamingo feathers. " Using deuterated BMAA, good recoveries were obtained after SPE. " DAB was found to occur at concentrations up to 8.5 lg g À1 in feathers. " BMAA and DAB co-occur with microcystins and anatoxin-a. " Feather analysis may be useful post-mortem to determine bird cause of death.

cal evaluation. Stressed animals had higher adrenal weights compared to non-stressed groups, which were reduced by 1400W treatment. Behavioural stress in sensitised animals amplified the resistance and elastance responses after antigen challenge, numbers of eosinophils and iNOS+ cells, actin content and 8-iso-PGF2 ␣ density in the distal lung compared to the OVA group. 1400W treatment in ovalbumin-exposed and stressed animals reduced lung mechanics, iNOS+ cell numbers and 8-iso-PGF2 ␣ density compared to sensitised and stressed animals that received vehicle treatment. We concluded that stress amplifies the distal lung constriction, eosinophilic inflammation, iNOS expression, actin content and oxidative stress previously induced by chronic lung inflammation. iNOS-derived NO contributes to stress-augmented lung tissue functional alterations in this animal model and is at least partially due to activation of the oxidative stress pathway.

Determination of sediment erosion and deposition fluxes from direct measurements associated with a drifting buoy in a tidal estuary, an application to the Seine (France). A direct evaluation of erosion and settling sediment fluxes, at the bottom boundary, is determined by measurements in a water column associated with a drifting buoy. The data were acquired during a high tide coefficient in the Seine estuary. The bed shear stress and the vertical sediment fluxes are regarded as independent variables. A new relation is proposed for calculating the total mass load of a given water column in a tidal estuary by knowing the friction velocity. © 2000 Académie des sciences / Éditions scientifiques et médicales Elsevier SAS sediment erosion / sediment deposition / sediment transportation / lagrangian coordinates Résumé -Une nouvelle méthode permettant l'évaluation directe des flux d'érosion et de dépôt de sédiments dans un estuaire macrotidal est proposée. Elle consiste à suivre les caractéristiques physiques, dont la charge solide, d'une colonne d'eau associée au déplacement d'une bouée dérivant dans l'estuaire de la Seine durant un cycle de marée de vive-eau. Cette démarche permet de considérer la contrainte de cisaillement sur le fond et le flux vertical des sédiments comme des variables indépendantes. Une relation entre la variation de la charge d'une colonne d'eau en matières en suspension et la vitesse de frottement sur le fond est suggérée. © 2000 Académie des sciences / Éditions scientifiques et médicales Elsevier SAS érosion de sédiment / dépôt de sédiment / transport sédimentaire / coordonnées lagrangiennes Abridged version * Correspondance et tirés à part : [email protected] 265 C. R. Acad. Sci. Paris, Sciences de la Terre et des planètes / Earth and Planetary Sciences 331 (2000) 265-270

The thermal decomposition of ferrocene combined with a catalyst-assisted structuring of a Si-substrate surface is a favourable way to produce Fe-filled carbon nanotubes in good quality and in high yields. In this work we have studied the growth of such aligned filled nanotubes on iron and cobalt pre-coated Si-substrates and their dependence on the deposition time. The nanotube diameter depends on the used catalyst metal on the substrate surface. Magnetization measurements were carried out perpendicular (along tube axis) and parallel to the substrate and show excellent coercivities, a strong uniaxial anisotropy (ratios of H c,per /H c,par up to 6) and high saturation magnetization moments per substrate square. The magnetic behavior has been also interpreted as a function of deposition time and of the catalyst metal on the substrate. These investigations were complemented by X-ray diffraction, which revealed a majority fraction of a-Fe and a small amount of Fe 3 C.

MnMoW-triple oxide catalyst for chlorine-less oxygen generating electrodes from seawater electrolysis were prepared by repeated anodic deposition of their oxides on Ti/IrO2 substrate. The durability of the electrodes were examined by electrolysis in 0.5 M NaCl solution at current density of 1000 Am−2 and compared with their corresponding electrodes that were prepared by continuous anodic deposition. The electrodes repeatedly and continuously deposited for 90 min kept the oxygen evolution efficiency higher than 99% for 2600 h and 120 h of electrolysis, respectively. The improvement in the electrode durability by repeated deposition was attributed to the formation of single phase oxide deposits of MnMoW-oxides with optimized thickness, composition and structural water content, which enables the reduction of the electrode overpotential for the oxygen evolution reaction and increase overall stability and adhesion of the oxide deposits to Ti/IrO2 substrate. A mechanism for oxygen evolution at the anode surface during electrolysis was proposed.► MnMoW-oxides developed as new anodes for oxygen evolution during seawater electrolysis. ► Repetition of anodic deposition extended the durability of the anodes. ► The high durability attributed to the formation of a single phase triple oxide.

A substantial part of eroded material can be deposited along the runoff pathway. This deposition process may alter the composition of the transported material. Topography-and vegetation-induced deposition processes were examined under laboratory conditions and at the hillslope and watershed scale.

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One of the aims of rock mechanics analysis is to predict fallouts in underground excavations. The objective of this paper was to study the relative importance of different strength parameters and their significance on the simulation of brittle failure and fallouts. This work was conducted as a parametric study, using numerical modelling and a number of approaches. The results were compared with observed fallouts. More obvious and distinct shear bands could be observed with decreased element sizes close to, and at, the boundary. The maximum shear strain was the most reliable indicator for fallout prediction. The results of the (instantaneous) cohesion softening friction softening models were sensitive to changes of the peak strength parameters and less sensitive to variations in residual parameters. The result from the cohesion-softening friction-hardening (CSFH) model, when using a peak cohesion equal to the intact rock strength, best captured the observed rock behaviour.

The most important nitrogen source for isolated heathland lakes in the Netherlands is the atmospheric deposition of nitrogen compounds. Calculations were performed to relate in-lake concentrations with deposition. Using a dynamic retention model, all major components deposited (NH4+, NO,-and SO,%) appeared to be retained by the lake. Simulations with the aquatic ecosystem model AquAcid showed a big discrepancy between calculated and measured concentrations when using the estimated total deposition. However, using only wet deposition data, a reasonable fit with measured datawas obtained. It was concluded that the dry deposition of nitrate and ammonium actually entering the lakes was far lower than the deposition estimated. The reasons for the apparent absence of dry deposition of nitrogen compounds on heathland lakes in general, and the impact on estimates of critical nitrogen deposition, are discussed.

The physical processes that control mineral sediment deposition on a mesotidal salt marsh surface on the Atlantic Coast of Virginia were characterized through a series of measurements of sediment concentration, flow velocity, turbulence, water surface elevation, marsh topography and particle size distributions of sediment deposited on the marsh surface. The comprehensive nature of the data set allowed assessment of the temporal and spatial variability in marsh surface deposition, the variability in depositional processes among tides of different amplitudes, as well as the specific processes that control deposition on this tidal marsh. Through three different types of measurements, it was found that sediment deposition occurred on the marsh surface during rising tides at tidal elevations ranging from those barely flooding the creek bank to high spring tides, and that sediment was not remobilized by tidal flows after initial deposition. Sediment deposition occurred on this marsh surface largely because fine sediment in suspension formed flocs. Analysis of inorganic grain size distributions of sediment deposited within 8 m of the tidal creek indicated that 70-80% of this sediment was deposited in a flocculated form. The rest (particles larger than 20 m) were deposited as individual particles. In the marsh interior, 25 m from the tidal creek, single grain settling predominated. Reduction of turbulence levels within the vegetation canopy on the marsh also promoted particle settling. The processes controlling sediment deposition did not vary among tides. However, suspended sediment concentrations near the creek bank increased with increasing tidal amplitude, consequently promoting higher rates of deposition on higher tides.

The boat-based, mobile mapping system (BoMMS) with a laser scanner allows the derivation of detailed riverine topographical data for fluvial applications. Combined with data acquisition from static terrestrial LiDAR (light detection and range) or mobile terrestrial LiDAR on the ground, boat-based laser scanning enables a totally new field mapping approach for fluvial studies. The BoMMS approach is an extremely rapid methodology for surveying riverine topography, taking only 85 min to survey a reach approximately 6 km in length. The BoMMS approach also allowed an effective survey angle for deep river banks, which is difficult to achieve with aerial or static terrestrial LiDAR. Further, this paper demonstrates the three-dimensional mapping of a point-bar and its detailed morphology. Compared with the BoMMS surface, approximately, 80% and 96% of the terrestrial LiDAR points showed a height deviation of less than 2 cm and 5 cm, respectively, with an overall standard deviation of ± 2·7 cm. This level of accuracy and rapidity of data capture enables the mapping of post-flood deposition directly after a flood event without an extensive time lag. Additionally, the improved object characterisation may allow for better 3D mapping of the point bar and other riverrine features. However, the shadow effect of the BoMMS survey in point bar mapping should be removed by additional LiDAR data to acquire entire riverine topography. The approach demonstrated allowed a large reach to be surveyed compared with static terrestrial LiDAR and increased the spatial limit of survey towards aerial LiDAR, but it maintains the same or even better temporal resolution as static terrestrial LiDAR. Copyright © 2009 John Wiley & Sons, Ltd.

In this paper the possibilities of focused ion beam (FIB) applications in microsystem technology are reviewed. After an introduction to the technology and the operating principles of FIB, two classes of applications are described. First the subject of FIB for microsystem technology inspection, metrology and failure analysis is outlined. A procedure for cross sectioning on samples is presented, as well as some examples of how this technique can be applied to study processing results. The second part of the paper is on the use of FIB as a tool for maskless micromachining. Both subtractive (etching) and additive (deposition) techniques are discussed, as well as the combination of FIB implantation of silicon with subsequent wet etching. We will show the possibility to fabricate three-dimensional structures on a micrometre scale, and give examples of recent realizations thereof.

The mechanisms of gold bioaccumulation by cyanobacteria (Plectonema boryanum UTEX 485) from gold(III)-chloride solutions have been studied at three gold concentrations (0.8, 1.7, and 7.6 mM) at 25°C, using both fixed-time laboratory and real-time synchrotron radiation absorption spectroscopy (XAS) experiments. Interaction of cyanobacteria with aqueous gold(III)-chloride initially promoted the precipitation of nanoparticles of amorphous gold(I)-sulfide at the cell walls, and finally deposited metallic gold in the form of octahedral (111) platelets (∼10 nm to 6 µm) near cell surfaces and in solutions. The XAS results confirm that the reduction mechanism of gold(III)-chloride to metallic gold by cyanobacteria involves the formation of an intermediate Au(I) species, gold(I)-sulfide.

Materials whose dielectric constant varies spatially with submicrometer periodicity exhibit diffractive optical properties which are potentially valuable in a number of existing and emerging applications. Here, such systems are fabricated by exploiting the spontaneous crystallization of monodisperse silica spheres into close-packed arrays. By reliance on a vertical deposition technique to pack the spherical colloids into close-packed silica-air arrays, high quality samples can be prepared with thicknesses up to 50 µm. These samples are planar and thus suitable for optical characterization. Scanning electron microscopy (SEM) of these materials illustrates the close-packed ordering of the spherical colloids in planes parallel to the substrate; cross-sectional SEM micrographs of the arrays as well as optical methods are used to measure sample thickness and uniformity. Normal-incidence transmission spectra in the visible and near-infrared regions show distinct peaks due to diffraction from the colloidal layers. While these basic optical characteristics are similar to thicker and polycrystalline gravity-sedimented colloidal crystals, the systematic control over the number of colloidal layers allows the effect of sample thickness on the optical spectrum to be studied for the first time.

The ability to atomize a liquid sample into femtoliter droplets and deposit them precisely on a surface is a key problem in microfluidics and chemical analysis. Here we show that control of stable oscillations in an unforced electrospray is a high accuracy drop-on-demand method of depositing femtoliter droplets. Examples are presented of a liquid jet, formed for 35 s, in a discontinuous spray mode controlled using electrostatic fields of short duration; no liquid pump was employed. Each transient jet ejects femtoliter volumes of material, which was deposited on a nearby surface. The volumes ejected by pulsating sprays on a range of nozzle sizes are predicted from electrospray scaling laws. Using the modified nanoelectrospray method, we have printed 1.4 m wide features onto a surface in a drop-on-demand fashion with a placement accuracy of a few micrometers. We anticipate that our technique could produce biological microarrays and precisely deliver ultra-small samples for lab-on-a-chip analysis. ᭧

Plusieurs études multidisciplinaires ont été effectuées sur les couches riches en matière organique (MO) de la Formation Bahloul. Nos études de terrain et les synthèses géologiques, géochimiques, isotopiques et minéralogiques disponibles ont permis d'apporter des précisions nouvelles d'ordre paléogéographique et paléocéanographique. Ces données ont contribué à l'élaboration d'un modèle de dépôt sous une zone à minimum d'oxygène (ZMO) dans des bassins marins profonds et subsidents de type bathyal, où se sont accumulées et préservées d'importantes quantités de MO (jusqu'à 18,7 % de COT). Le présent modèle a permis la corrélation de la Formation Bahloul à d'autres coupes de référence à l'échelle globale, ce qui permet de mettre en évidence que le d 13 C mesuré sur MO serait un meilleur outil de corrélation que le d 13 C mesuré sur carbonates pour reconnaître la limite Cénomanien/Turonien. Mots clés Formation Bahloul ; Géochimie ; Stratigraphie ; EAO-2 ; Cénomanien-Turonien ; matière organique; modèle de dépôt.

In order to find the optimal windbreak design in terms of its porosity, its distribution with height and the number of rows needed, a wind-tunnel study was conducted. Measurements of the total wind-velocity reduction coefficient of windbreaks with a porosity ranging from 0 to 1 m 2 m À2 showed that a Gaussian peak function fitted very well to the data. It was concluded that a porosity of 0.20-0.35 m 2 m À2 is optimal in terms of wind-velocity reduction. With regards to the distribution of porosity with height, an evenly distributed porosity of stem and canopy resulted in the longest protected area, i.e. the area where the wind-velocity reduction is more than 50%. This was also the case for single-row barriers compared to two-and three-row windbreaks. Experiments with dry loose dune sand were conducted to deduce zones of erosion and deposition behind differently designed windbreaks. The observed zones could be well explained by considering the threshold wind velocity that was computed for the dune sand used in combination with isowind-velocity lines. The results are useful for construction of windbreaks. However, one should bear in mind that the optimal design depends strongly on the purpose for which it is constructed, viz. protection of a field from being eroded or protection of infrastructure from being buried. r

Electron beam lithography is generally accepted to have the highest practical resolution capability. In this paper the state of the art in terms of resolution is reviewed. This covers conventional resists such as PMMA, contamination resist, inorganic resists and damage processes. Some insights into the resolution limiting factors are given although the precise limitations still remain unclear. Consideration is also given as to the best measure of resolution and it is suggested that the minimum line spacing is a more appropriate and less subjective measure than minimum achievable feature size.

Um Rituale beim prähistorischen Hausbau zu identifizieren, müssen intentionelle, regelhafte, wiederholte Befunde untersucht werden, denen kein funktionaler Zweck beigemessen werden kann. Mit Hilfe der genannten Kriterien werden Funde aus Pfostenlöchern einer Analyse unterzogen. Als Ergebnis zeigen die Deponierungen in Pfostenlöchern der Urnenfelder-, Hallstatt- und Frühlatènezeit aus Bayern, Böhmen und Österreich Regelmäßigkeiten im Richtungsbezug und in der Auswahl der Gegenstände. Anstelle einer pauschalen Deutung dieser Deponierungen als „Bauopfer“ sollen kontextuelle Untersuchungen zu einer differenzierten Interpretation führen. Demnach kann zwischen Trink- und Speiseopfern, die im Rahmen des kollektiven Bauens typisch sind, und Deponierungen von Schmuck- und Trachtgegenständen, die möglicherweise mit der Demonstration von Reichtum oder mit Rechtsbräuchen zu tun haben, unterschieden werden. Die bevorzugte Deponierung im Südwesten der Häuser stimmt mit der Ausrichtung hallstattzeitlicher Körperbestattungen in den untersuchten Regionen überein. Dieser symbolische Bezug deutet auf kosmologische Vorstellungen hin, die nicht nur im Grab, sondern auch beim Hausbau berücksichtigt wurden.

, and the origin of unconformity-bounded depositional sequences. Mar. Geol., 97: 35-56. Unconformity-bounded depositional sequences represent the fundamental building blocks of sedimentary successions. They are typically characterized by onlap at the base and by offlap at the top, and they tend to be markedly asymmetrical, with onlap accounting for a larger part of any cycle of sedimentation than offlap. Offlap cannot be attributed solely to erosional truncation, but instead implies that sequence boundaries develop over a finite interval of time. Depositional sequences are commonly associated with a cyclic arrangement of facies, but transgressive-regressive cycles are out of phase with respect to sequence boundaries, which in down-dip locations are both overlain and underlain by progradational deposits, and hence form during times of regression of the shoreline. These observations are used to develop some ideas about the origin of unconformity-bounded sequences, with reference to the inter-related roles of changes in depositional base level and sediment supply. In particular, it is shown than onlap and offlap are due to lateral migration of a "line of critical bypassing", defined so as to incorporate the effects of sediment loading and compaction as well as the rate of change of elevation with respect to sea level. Downward shifts in onlap may be achieved by either an increase in the rate of eustatic fall or a decrease in the rate of tectonic subsidence, and it is premature to assume that eustatic and tectonic controls on sea level may be distinguished solely on the basis of the frequency of depositional cyclicity. Small shifts in the position of onlap can also be produced by changes in sediment supply, and more attention needs to be paid to the influence of sediment supply in the development of minor boundaries. Unconformities related to eustatic fluctuations are thought to correspond approximately to times of relatively rapid sea-level fall (inflection points), but questions remain about the existence of possible leads and lags of up to ~ cycle, and hence about the degree to which sequence boundaries of eustatic origin may vary in age both within a given basin and from one basin to another.

Over the past two years, the U.S. Army Engineer Research and Development Center and the Defence R&D Canada Valcartier have partnered to develop an improved understanding of the distribution and fate of propellant residues on military training ranges in SERDP Project ER-1481. As a portion of this work, field studies have been conducted to estimate the mass of propellant residues deposited per round fired from various munitions. This research included artillery, mortars, small arms, shoulder-fired rockets, and several large missiles. Particles of the propellant residues deposited have been collected and studied, and initial experiments conducted to measure the rate of release of nitroglycerin (NG) and 2,4-dinitrotoluene (DNT) after deposition. Field studies have been conducted at a number of U.S. and Canadian installations to determine the mass and distribution of residue accumulation from different types of munitions. Depth profiling has been accomplished to document the depth to which these residues have penetrated the shallow subsoil. Laboratory column studies have been conducted with NG, nitroguanidine, and diphenylamine to document transport rates for solution phase propellant constituents and develop process descriptors for use in mathematical models to enable prediction of fate and transport for these constituents. Subsequent column studies have utilized intact propellants. The major accomplishments from these field and laboratory studies are presented.

Through the years, Danish utilities have gained significant knowledge on how to minimize or even avoid ash deposition problems in utility boilers, firing worldwide high-volatile bituminous coals. In the early 90ties, the Danish Government decided on a 20 % reduction in the CO 2 -emission before the year 2005, based on the 1988-level. Biomass is considered CO 2 -neutral due to its short time of regeneration compared to fossil fuels. Thus, the Danish power producers are enjoined to burn 1.0 Mtons of straw, 0.2 Mtons of wood chips and 0.2 Mtons of straw/wood chips (free choice) every year beyond year 2005. As a consequence of this, the CHEC Research Centre, Department of Chemical Engineering, Technical University of Denmark, being partly funded by the Danish power utilities, has during the last decade, investigated ash and deposit formation, and corrosion, in utility boilers fired with coal, petcoke, orimulsion, and different types of biomass (straw (barley, rape and wheat), wood (beech, spruce, fibreboard, bark and waste wood), shea nuts, olive stones etc.).

El presente articulo muestra los resultados del trabajo experimental sobre suelos fino granulares del municipio de Itagui, asociados al deposito aluvial de la quebrada Dona Maria (Antioquia-Colombia). Se utilizaron muestras compactadas a las que se les determino la succion matricial por el metodo del papel filtro y la tecnica de traslacion de ejes, para diferentes contenidos de humedad. Adicionalmente, se tomaron mediciones de volumen en las muestras durante el proceso de humedecimiento. A partir de los resultados experimentales, se elaboro la curva caracteristica humedad succion del suelo (SWCC) y se analizaron las relaciones de la succion con el contenido de humedad, el grado de saturacion y el cambio de volumen del suelo. Los resultados mostraron que los mayores cambios en la relacion de vacios de los suelos estudiados, se iniciaron a un grado de saturacion cercano al 50%. Para saturaciones menores del 50%, en proceso de humedecimiento, la relacion de vacios permanecio estable y ...

Although algal blooms, including those considered toxic or harmful, can be natural phenomena, the nature of the global problem of harmful algal blooms (HABs) has expanded both in extent and its public perception over the last several decades. Of concern, especially for resource managers, is the potential relationship between HABs and the accelerated eutrophication of coastal waters from human activities. We address current insights into the relationships between HABs and eutrophication, focusing on sources of nutrients, known effects of nutrient loading and reduction, new understanding of pathways of nutrient acquisition among HAB species, and relationships between nutrients and toxic algae. Through specific, regional, and global examples of these various relationships, we offer both an assessment of the state of understanding, and the uncertainties that require future research efforts. The sources of nutrients potentially stimulating algal blooms include sewage, atmospheric deposition, groundwater flow, as well as agricultural and aquaculture runoff and discharge. On a global basis, strong correlations have been demonstrated between total phosphorus inputs and phytoplankton production in freshwaters, and between total nitrogen input and phytoplankton production in estuarine and marine waters. There are also numerous examples in geographic regions ranging from the largest and second largest U.S. mainland estuaries (Chesapeake Bay and the Albemarle-Pamlico Estuarine System), to the Inland Sea of Japan, the Black Sea, and Chinese coastal waters, where increases in nutrient loading have been linked with the development of large biomass blooms, leading to anoxia and even toxic or harmful impacts on fisheries resources, ecosystems, and human health or recreation. Many of these regions have witnessed reductions in phytoplankton biomass (as chlorophyll a) or HAB incidence when nutrient controls were put in place. Shifts in species composition have often been attributed to changes in nutrient supply ratios, primarily N:P or N:Si. Recently this concept has been extended to include organic forms of nutrients, and an elevation in the ratio of dissolved organic carbon to dissolved organic nitrogen (DOC:DON) has been observed during several recent blooms. The physiological strategies by which different groups of species acquire their nutrients have become better understood, and alternate modes of nutrition such as heterotrophy and mixotrophy are now recognized as common among HAB species. Despite our increased understanding of the pathways by which nutrients are delivered to ecosystems and the pathways by which they are assimilated differentially by different groups of species, the relationships between nutrient delivery and the development of blooms and their potential toxicity or harmfulness remain poorly understood. Many factors such as algal species presence/ abundance, degree of flushing or water exchange, weather conditions, and presence and abundance of grazers contribute to the success of a given species at a given point in time. Similar nutrient loads do not have the same impact in different environments or in the same environment at different points in time. Eutrophication is one of several mechanisms by which harmful algae appear to be increasing in extent and duration in many locations. Although important, it is not the only explanation for blooms or toxic outbreaks. Nutrient enrichment has been strongly linked to stimulation of some harmful species, but for others it has not been an apparent contributing factor. The overall effect of nutrient overenrichment on harmful algal species is clearly species specific.

Carbon possesses unique electrical and structural properties that make it an ideal material for use in fuel cell construction. In alkaline, phosphoric acid and proton-exchange membrane fuel cells (PEMFCs), carbon is used in fabricating the bipolar plate and the gas-diffusion layer. It can also act as a support for the active metal in the catalyst layer. Various forms of carbon -from graphite and carbon blacks to composite materials -have been chosen for fuel-cell components. The development of carbon nanotubes and the emergence of nanotechnology in recent years has therefore opened up new avenues of materials development for the low-temperature fuel cells, particularly the hydrogen PEMFC and the direct methanol PEMFC. Carbon nanotubes and aerogels are also being investigated for use as catalyst support, and this could lead to the production of more stable, high activity catalysts, with low platinum loadings (<0.1 mg cm −2 ) and therefore low cost. Carbon can also be used as a fuel in high-temperature fuel cells based on solid oxide, alkaline or molten carbonate technology. In the direct carbon fuel cell (DCFC), the energy of combustion of carbon is converted to electrical power with a thermodynamic efficiency close to 100%. The DCFC could therefore help to extend the use of fossil fuels for power generation as society moves towards a more sustainable energy future.

Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m −2 year −1 in small diameter mountain hemlock stands to ∼300 g m −2 year −1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m −2 year −1 for small diameter stands of Jeffrey pine to 126.9 g m −2 year −1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to estimate fuel treatment longevity, assist in determining fuel model transitions, and predict future changes in fuel bed characteristics.

Crystalline semiconductors are very well known, including silicon (the basis of the integrated circuits used in modern electronics), Ge (the material of the first transistor), GaAs and the other III-V compounds (the basis for many light emitters), and CdS (often used as a light sensor). In crystals, the atoms are arranged in near-perfect, regular arrays or lattices. Of course, the lattice must be consistent with the underlying chemical bonding properties of the atoms. For example, a silicon atom forms four covalent bonds to neighboring atoms arranged symmetrically about it. This "tetrahedral" configuration is perfectly maintained in the "diamond" lattice of crystal silicon.

The passage tomb at Newgrange serued as a focus of ceremonial actiuity in tbe Late Neolitbic and Beaker periods. A complex of monuments wds constructed around the mound, consisting of a timber circle or woodhenge to the south-east and a smaller, possibly roofed, timber circle to tbe west; an enclosing bank constructed along tbe southern and western sides, and a free-standing circle of great stones encircling the monument. In this paper tbe uiew that the faunal and material remains from the Newgrange excauations are domestic refuse is questioned. Tbe deposition and spatial patterning of tbe faunal material is interpreted as hauing a ritual significance and the use of tbis material as representatiue of the Late l,leolithiclBeaker period economy is reiected l;

Troubleshooting of scale deposits and defects in paper samples showed that the problem was caused by barium sulphate and calcium sulphate scales. However, it was ascertained that barium sulphate was more of a concern than calcium sulphate as it is more tenacious than the calcium sulphate scale. A study of the inputs of the scale components found that the major inputs of barium into the mill system were the wood chips and bark contamination. The major inputs of the sulphate component of the scale were sulphuric acid used for pH control and alum used for rosin sizing.Evaluation of several options for mitigating the scale deposition problem showed that bark removal and continuous application of a scale inhibitor comprised of phosphates/phosphonates and polyacrylates were effective in reducing and controlling the scale deposit problems. Institution of these measures led to a cleaner paper machine that required far fewer boil outs than before. In addition, productivity improved and the fisheye defects disappeared.A rapid method was developed for on-site estimation of barium levels in mill process samples. The data were used to adjust the dosage of the scale inhibitor to ensure optimum effectiveness of the programme.

Metals are common contaminants worldwide. Long-term deposition of metals in soils can lead to accumulation, transport and biotoxicity/zootoxicity caused by mobility and bioavailability of significant fraction of the metals. Contaminant bioavailability is increasingly being used as a key indicator of potential risk that contaminants pose to both environmental and human health. However, the definition of bioavailability and the concepts on which it is based are still unclear, the methods adopted for its measurement vary and as such there is no single standard technique for the assessment of either plant availability of contaminants or their ecotoxicological impacts on soil biota. Moreover, bioavailability is often assumed to be static in nature where most decisions on risk and remediation are based on laboratory estimations of the bioavailable fraction, which may vary with time, nature of species as well as with temporal variation in environmental factors. Because of their immutable nature, strict natural attenuation processes alone may not be sufficient in mitigating the risks from metals. However, accelerating these processes with human interference (i.e., assisted natural remediation) that effectively immobilizes metals might be a viable option. Application to soils of certain amendments that enhance key biogeochemical processes in soils that effectively immobilize metals have already been demonstrated in Europe and North America on a field scale. Case studies using lime, phosphate and biosolid amendments have demonstrated, under field conditions, enhanced natural remediation resulting in substantially improved vegetation growth, invigorated microbial population and diversity, and reduced offsite metal transport. Depending on soil/hydrogeochemical properties, source term and metal form/species, and land use, the immobilization efficacy induced by such assisted natural remediation may be enduring. The use of green plants as a remediation tool in environmental cleanup has also offered some potential. Plants can uptake and bioaccumulate (phytoextraction) as well as immobilize (phytoimmobilization) certain trace elements, in conjunction with their rhizospheric processes. While long-term stability of certain metal complexes, such as metal pyromorphites has been shown in model systems, the influence of plant roots and its microbial and mycorrhizal association on such stability is unknown. A suite of chemical and biological tests are available to monitor the efficacy of assisted natural remediation. D

I Nl Ih~hh mlIII ,4 9-9 A. Approved for public release; Distribution is unlimited I NOTICES When Government drawings, specifications, or other data are used for any purpose other than in connection with a definitely related Government procurement operation, the United States Government thereby incurs no responsibility nor any obligation whatsoever, and the fact that the Government may have formulated, furnished, or in any way supplied the said drawings, specifications, or other data, is not to be regarded by implication or otherwise as in any manner licensing the holder or any other person or corporation, or conveying any rights or permission to manufacture, use, or sell any patented invention that may in any way be related thereto. I O5T2-101 REPORT DOCUMENTATION 1 1. REPORT NO. 2. s. Recipient's Accession No. PAGE 4. Title and Subtitle 5. Report Date Appendix November I q92 Joint Services Electronic Program-Fifteenth Annual Report N. 7. Author(s) a. Performing Org. Rept. No.

Silicon Dioxide (SiO 2 ) thin film deposition processes were studied with use of classical Molecular Dynamics (MD) simulations combined with Monte Carlo (MC) simulations. The MC simulations are shown to efficiently emulate thermal annealing processes during deposition. Dependence of various film properties on the incident atomic kinetic energies and incident angles is examined based on the numerical simulations.

Deposition of complex and heavy organic compounds, which exist in petroleum crude and heavy oil, can cause a number of severe problems. To prevent deposition inside the reservoir, in the well head and inside the transmission lines, it is necessary to be able to predict the onset and amount of deposition due to various factors. In the present paper, the mechanism of asphaltene deposition, which is the major cause of most organic deposition cases, is modeled based on statistical mechanics of polydisperse polymer solutions joined with the kinetic theory of aggregation and its predictive capability is discussed. Utilization of statistical mechanics of polydisperse polymer solutions joined with kinetic theory of aggregation enables us to develop a realistic model which is able to predict both reversible and irreversible heavy organic depositions. The present model is capable of describing several reversible and irreversible situations, such as the phenomena of organic deposition, growing mechanism of heavy organic aggregates, the size distributions of precipitated organics and the solubility of heavy organics in a crude oil due to variations in oil pressure, temperature and composition. As an example, the present model is applied for heavy organics deposition prediction of two different Brazilian crude oils for which experimental data are available. It is shown that the prediction results of the present model are in good agreement with the experimental data.