Variation Of Deposition Rate Research Articles

Effect of low nitrogen concentration on reactive RF sputtering of boron

Monolayer boron and B/Mo/B/Mo coatings were prepared by reactive magnetron sputtering in the N2/Ar atmosphere with different RF powers, and the effect of the N2:Ar flow ratio was studied. It was found that as the N2:Ar flow ratio increased, the deposition rate of boron coatings exhibited three different stages of variation due to different mechanisms. The variation of deposition rate with increasing N2:Ar flow ratio was consistent for different RF powers. Berg's model explained experimental findings. XPS revealed that the coatings contained more than 86 % boron nitride (BN) when the N2 flow ratio was above 0.053 at 300W RF power. An optimal ratio exists that maximizes the boron deposition rate and produces a nearly pure boron nitride coating without target poisoning.

Martensitic ternary FeCrMn thin films sputtered from austenitic AISI 202 stainless steel target: Phase transition and corresponding magnetic properties under the influence of deposition rate

The nanostructured materials exhibit quite different properties from their bulk counterparts. Therefore, in this work, phase transition from a commercial austenitic AISI 202 (Bulk FeCrMn) stainless steel to martensitic ternary FeCrMn thin films under variation of deposition rate were studied. The films were easily sputtered onto a flexible amorphous polymer substrate from the target by a DC magnetron. X-ray diffraction analysis showed that austenitic phase of the target converted into a mixture of martensitic and a very weak of austenitic phase of the films at the deposition rates of 0.04 and 0.06 nm/s. With a further increase of the deposition rate, martensitic phase in the films increased, and at the highest deposition rate, the film with 100 % martensite phase was obtained. According to magnetic analysis, austenitic target consists of paramagnetic and ferromagnetic components as oppose to the paramagnetic phase stated in the literature. The films obtained by sputtering of austenitic target have ferromagnetic character with an increasing saturation magnetization, MS as the deposition rate increases. The increase of the MS from 117 to 346 emu.cm−3 may be explained by the increase of the % martensite that may increase the ferromagnetic character. Also, the increase of the coercivity of the films from 31 to 196 Oe may have come from the increase of % martensite and the increase of grain sizes with increasing deposition rates which may induce the stress in the films. It is seen that the nanostructured ternary FeCrMn thin films exhibit quite different phase and corresponding magnetic properties from their bulk counterpart. With sputtering, martensitic phase transition of ternary FeCrMn thin films can be controlled by varying deposition rates. It presents a potential usage for data storage and micro electric-electronic devices on flexible substrates.

Coal-derived rates of atmospheric dust deposition during the Jurassic-Cretaceous greenhouse periods

The study of dust deposition records in geological history is of great significance to the study of paleoclimate evolution during deep periods. Because dust can directly influence the biochemical processes and climate evolution of the Earth. However, the absence of quantitative data on dust limits the systematic and comprehensive study of paleoclimate evolution during deep periods. Prior to the Quaternary period, most quantitative studies on atmospheric dust have focused on the Permian era. However, in the entire Mesozoic era, there are still no quantitative data available on atmospheric dust deposition rates. We utilized the average concentration of inorganic matter in coal from the Jurassic and Cretaceous periods to depict the dust concentration and corresponding dust deposition rate in the atmospheric system during these periods. We also conducted a correlation analysis using the distribution of arid source areas. The results show that the values of ash concentration and dust deposition rates are higher near the arid provenance and lower far away from it. Furthermore, in this study, we have compared the latitudinal variation gradient of dust deposition rates under the icehouse and greenhouse climates by using the end of the Permian and Quaternary as representatives of icehouse climate and the Jurassic and Cretaceous periods as representatives of the greenhouse climate. Our findings indicate that there is a higher ash concentration, dust deposition rate, and dust deposition rate variation gradient in the air under the icehouse climate, while there is a lower ash concentration, dust deposition rate, and dust deposition rate gradient in the air under the greenhouse climate. We have also discussed the dust sources during the Mesozoic period, as well as the differences in ash data under greenhouse and icehouse conditions. This provides a strong basis for studying the atmospheric environment after the modern climate entered the ice age.

Multi‐Centennial Variability of Yangtze Delta Growth Over the Last 2000 Years: Interplay of Climate and People

AbstractReconstruction of sediment accumulation in river deltas over the Holocene provides a basis for understanding the relationship between climate change, human activities and delta growth. However, variations in deposition rates on a centennial‐scale over the last 2000 years remain poorly studied for mega‐deltas. Based on optically stimulated luminescence and AMS 14C ages, we calculated deposited sediment volumes in the Yangtze River Delta (YRD) for 500‐year intervals over the last two millennia for the first time. Our results reveal that the 2.0–1.5 and 0.5–0 ka periods had higher sediment deposition rates than in 1.5–1.0 and 1.0–0.5 ka, with maximum value about two times that of the minimum. A comparison with historical records of flooding and drought events indicates that a wetter climate led to a higher sediment deposition, reflecting the role of fluvial discharge in delta growth. However, the highest sediment deposition (205 ± 29 × 106 m3/a) over the last 500 years is not only related to the wetter conditions of the Little Ice Age, but also linked to dramatic regional population growth. We suggest that human activities have predominated over natural forcing in determining the deltaic growth over the last five centuries. Taking the Medieval Climate Anomaly with the lowest deposition volume as an analog of current climate warming, and considering the decline in sediment loads due to recent damming and soil conservation, the YRD is likely to face an even more severe deficit in sediment supply and higher risk of delta destruction in the coming centuries.

How fast do submarine fans grow? Insights from the Quaternary Golo fans, offshore Corsica

Abstract High-resolution seismic, core, and chronological data from the Quaternary Golo deep-sea fans, offshore Corsica, France, give new insights into rates of submarine fan growth. Average vertical deposition rates for units that represent the Late Pleistocene glacial periods are 0.1–0.5 m/k.y. Glacial-age deposits are sand rich; in contrast, post-glacial deposits lack a significant sand fraction and are dominated by carbonate-rich mud. As a result, seismically constrained volumetric rates of deposition for glacial periods with low sea level and a subaerially exposed shelf are ∼0.23 km3/k.y., 2×–5× higher than rates during interglacials when sea level is high, the shelf is submerged, and sand is trapped in shallow-marine environments. At millennial time scales, variations in deposition rate reflect climate-driven sea-level changes, autogenic avulsion of river channels that extend across the shelf during low sea level, and autogenic avulsion of submarine channels that shift the locus of deposition laterally. Short-term deposition rates range from 8.6 m/k.y. at proximal portions of submarine fans to 0.4 m/k.y. along the distal fringe. Our data show that submarine fans can be dynamic environments with formation and evolution of levee-confined channels and lobe complexes in 103–104 yr, comparable to the time scales needed to form fluvial channel belts and delta lobes.

Long-term thermal oxidative deposition of RP-3 jet fuels: Mechanism and modeling

The long-term thermal oxidative deposition of jet fuel is of great significance for the design and applications of the fuel-cooled thermal management of advanced aircrafts. In this paper, the long-term (100 h) thermal oxidative deposition of RP-3 jet fuel was carried out in the electric heating tube to understand the complex time-dependent deposition phenomena and behaviors. It was found that there are three typical deposition rates stages in 100 h time-on-stream (TOS) experiment, i.e., the initial stage, the growth stage, and the decline stage. In the initial stage (0–2 h), the average deposition rate continuously decreases by almost 5 times from 8.70 mg/h at 0 h to 1.73 mg/h at 2 h ascribed to the gradual coverage of metal surface by the deposition, and then grows by 4.37 times from 1.73 mg/h at 2 h up to 7.56 mg/h at 70 h attributed to the increased wall surface area from 0.01074 m2 to 0.02483 m2 by the solid deposit in growth stage. However, in the decline stage the average deposition rate slightly decreases to 7.08 mg/h at 100 h as a result of the reduction of local residence time as well as the possible aging of deposition layer. A simplified kinetic model of long-term thermal oxidative deposition process was proposed to describe the complex deposition rate variation and validated that the error between the prediction of total deposition amount and the experimental data is less than 10%.

Impacts of carrier properties, environmental conditions and extracellular polymeric substances on biofilm formation of sieved fine particles from activated sludge

To investigate the effect of properties of carriers, environmental conditions and extracellular polymeric substances (EPS) on the initial adhesion of biofilm formation in biofilm-based reactors, a quartz crystal microbalance with dissipation (QCM-D) was applied to monitor the deposition rates and viscoelastic properties of sieved sludge particles on model biocarriers. The results suggested that surface charge, hydrophobicity and surface coating of five representative carriers influenced deposition rates and viscoelastic properties of biofilm, whose variation with NaCl concentrations was controlled by not only the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction but also non-DLVO forces. On hydrophobic surface, the addition of cationic substances enhanced the deposition rates and the compaction of deposited layer due to strong “hydrophobizing effect”. For examples, 10 mM Ca2+, 10 mM Mg2+ and 10 mg/L poly-l-lysine enhanced the deposition rates to nearly 3, 2 and 4 times, as well as reduced the softness of deposited layer to almost 35%, 60% and 35%. Conversely, 10 mg/L negatively charged alginate might cause water retainment and steric shielding, thereby reducing the deposition rates to 40% and increasing the softness of deposited film to 120%. The presence of EPS sub-fractions can modify surface properties of sludge particles, to distinct degrees, contributing to biofilm formation. Notably, compared to tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS) was more conducive to microbial attachment, but the presence of LB-EPS promoted the formation of a soft layer on a hydrophobic surface. Overall, these results provide insights into intrinsic mechanisms of the variation of deposition rates and viscoelastic properties responding to critical factors, which are meaningful to predict and regulate the initial adhesion process in biofilm-based reactors.

Characterization and electrochemical deposition of natural melanin thin films

Melanin is an important class of biological pigments because of its distinct chemical and physical properties. The electrochemical deposition of natural melanin thin films was studied using two different techniques; constant potential and cyclic voltammetry along with a deposition time of five hours. The thin films deposited electrochemically on a fluorine-doped tin oxide conductive glass substrate using the constant potential method, exhibited faster growth rate and better adhesion to the fluorine-doped tin oxide working electrodes than those deposited using the cyclic voltammetry method. The thin films deposited on the fluorine-doped tin oxide conductor glass using the constant potential method were also more homogeneous than those deposited via the cyclic voltammetry technique. The increase of film thickness is related to the increase of electrochemical deposition time. Interestingly, the electrochemical deposition using the constant potential method had the advantage of consuming less electric charge. The physical and chemical structures of the melanin thin films were characterized using ultraviolet–visible absorption spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analysis. The ultraviolet–visible absorption spectra showed the correlation between the variation of deposition rates of melanin and the type of electrochemical technique employed as well as the thickness of the film. The average thickness of the film is 500 nm which absorb 40% of light in both type of films. The atomic force microscopy images illustrated the homogeneous deposition of the melanin molecules on the fluorine-doped tin oxide conductive glass substrate, indicating that the thickness of the thin films can be controlled. We estimated an average grain size of 14.093 Å. The ease of preparing such thin films of organic materials can open new avenues towards the use of soft conductors, in contrast to the complex preparation of industrial semiconductors.

Atmospheric deposition across the Atacama Desert, Chile: Compositions, source distributions, and interannual comparisons

Hyper-arid areas such as the Atacama Desert accumulated significant amounts of insoluble dust and soluble salts from the atmosphere, providing minable salt deposits as well as mimicking the surface processes on Mars. The deposition rates, compositions and sources, however, were poorly constrained. Especially, the variabilities of atmospheric deposition in the Atacama Desert corresponding to a changing climate were unassessed. In this work, the atmospheric depositions collected using dust traps across a west-east elevation gradient in the Atacama (~23°S) from 1/2/2010 to 12/31/2011 were analyzed and compared to previous results in 2007–2009. The insoluble dust deposition rates in our sampling period were significantly higher than those of 2007–2009 in most dust traps, which was attributed to the changes in wind, highlighting the importance of long-term monitoring of insoluble dust fluxes. Soluble salts, instead, showed less distinct interannual variations in deposition rates, geochemical compositions or source contributions. At the coastal site (T1), soluble salts were originated from both primary sea-salt (SS) aerosols and non-sea-salt (NSS) sources such as anthropogenic emission, marine biogenic emission and biomass burning; the deposition rates of these salts largely depended on the wind speed and the amount of anthropogenic emissions. Sulfur isotopic evidence further showed that NSS sulfate at T1 was mainly originated from local SO2 emission from local power plants. The inland sites (T2-T8) displayed much lower soluble salts deposition rates, and the salts were primarily sourced from entrainment of local surface minerals, including Na(Cl, NO3), CaSO4, and nitrate formed via atmospheric oxidation of anthropogenic NOx. Sulfur isotopic compositions of sulfate deposited at T2-T8 were similar to those in local surface soil; however, three sites near the Chuquicamata mine showed slightly lower δ34Ssulfate values, indicating the presence of secondary sulfate originated from mining activities. The soluble salts deposited at the Andean site (T10) were dominantly from wet deposition that incorporated local lake salts, and therefore, the deposition rates were mainly controlled by the amount of precipitation.

Engineered omnidirectional antireflection ITO nanorod films with super hydrophobic surface via glancing-angle ion-assisted electron-beam evaporation deposition

Growths of the indium tin oxide (ITO) nanorod films have been demonstrated by ion-assisted electron-beam evaporation with the glancing-angle deposition technique based on variation in deposition rate. Investigations have been performed on nanostructured ITO films deposited on ITO-coated commercial substrates in comparison to bare substrates. The physical microstructures have been investigated by grazing-incident X-ray diffraction (GIXRD), field-emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The electrical, optical, and hydrophobic properties were characterized by four-point probe measurements, UV–Vis–NIR spectrophotometry with angle-dependent technique, and contact angle goniometry, respectively. The results indicated that physical morphologies and nanorod diameters of ITO nanorod films were heavily influenced, and thus could be controlled, by deposition rate. The primary reason was self-annealing effect which occurred during film deposition and was crucial factor towards surface diffusion and film crystallinity. From the optical examinations, ITO nanorods deposited on the ITO-coated glasses exhibited significant improvements on transparent conductive oxide (TCO) properties from reference samples. The proposed ITO materials could therefore function as omnidirectional anti-reflection materials and super hydrophobic surface. This work have also proved that the ITO nanorods prepared by the electron-beam evaporation with the GLAD technique was highly promising for solar cell and optoelectronic applications.

Impact of deposition-rate fluctuations on thin-film thickness and uniformity.

Variations in deposition rate are superimposed on a thin-film deposition model with planetary rotation to determine the impact on film thickness. Variations in magnitude and frequency of the fluctuations relative to the speed of planetary revolution lead to thickness errors and uniformity variations up to 3%. Sufficiently rapid oscillations in the deposition rate have a negligible impact, while slow oscillations are found to be problematic, leading to changes in the nominal film thickness. Superimposing noise as a random fluctuation in the deposition rate has a negligible impact, confirming the importance of any underlying harmonic oscillations in the deposition rate or source operation.

Vertical La0.7Ca0.3MnO3 nanorods tailored by high magnetic field assisted pulsed laser deposition.

La0.7Ca0.3MnO3 (LCMO) thin films on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001) [LSAT (001)] single crystal substrates have been prepared by high magnetic field assisted pulsed laser deposition (HMF-PLD) developed by ourselves. Uniformly sized and vertically aligned nanorod structures can be obtained under an applied high magnetic field above 5 T, and the dimension size of the nanorods can be manipulated by varying the applied magnetic field. It is found that the magnetic anisotropy is strongly correlated to the dimension size of the nanorods. A significantly enhanced low-field magnetoresistance (LFMR) of −36% under 0.5 T at 100 K can be obtained due to the enhanced carrier scattering at the vertical grain boundaries between the nanorods for the LCMO films. The growth mechanism of the nanorods has been also discussed, which can be attributed to the variation of deposition rate, adatom surface diffusion, and nucleation induced by the application of a high magnetic field in the film processing. The successful achievements of such vertical nanorod structures will provide an instructive route to investigate the physical nature of these nanostructures and achieve nanodevice manipulation.

High-Throughput Multi-Plume Pulsed-Laser Deposition for Materials Exploration and Optimization

ABSTRACT A high-throughput multi-plume pulsed-laser deposition (MPPLD) system has been demonstrated and compared to previous techniques. Whereas most combinatorial pulsed-laser deposition (PLD) systems have focused on achieving thickness uniformity using sequential multilayer deposition and masking followed by post-deposition annealing, MPPLD directly deposits a compositionally varied library of compounds using the directionality of PLD plumes and the resulting spatial variations of deposition rate. This system is more suitable for high-throughput compound thin-film fabrication.

Pengaruh Laju Deposisi Terhadap Morfologi Lapisan Zinc Phthalocyanine (ZcPc) Di Atas Permukaan Polistiren/QCM dengan Proses Evaporasi Vakum

Deposition of zinc phthalocyanine (ZnPc) layer on top polistiren surface by vacuum evaporation method has been investigated. PS layer was coated on QCM surface by spin coater and ZnPc layer was deposited on its surface by vacuum evaporator with three variation of deposition rate, i.e 1.39 ´ 10 -4 , 8.08 ´ 10 -2 dan 7,41 ´ 10 -1 μm/s. The morphology and surface roughness of ZnPc layer was observed by scanning electron microscope (SEM) and non-contact topography measurement system TMS-1200 TopMap. SEM image of ZnPc layer with deposition rate of 1.39 ´ 10 -4 , 8.08 ´ 10 -2 and 7.41 ´ 10 -1 μm/s shows porous and fibre like structure. The size of pores and fibre structures of ZnPc layer that produced by deposition rates of 1.39 x10 -4 and 8.08 x10 -2 μm/s is smaller than size of pores and fibre that produced by 7.41 ´ 10 -1 μm/s. Moreover, increasing the deposition rate result a lot of ZnPc molecules make a bonding as fibrous result in the volume of fibrous increasing. Moreover, the increasing fibre size result pores volume increase. Therefore deposition rate can affect surface roughness, and roughness value is proportional to morphology of ZnPc layer. Based on result of TMS-1200 TopMap, the highest roughness level is 1310 nm, it’s found on the ZnPc layer that produced by deposition rate of 7,41 ´ 10 -1 μm/s.

Influence of the Temporal Deposition of Extracellular Matrix on the Mechanical Properties of Tissue-Engineered Cartilage

Enhancement of the load-bearing capacity of tissue-engineered (TE) cartilage is expected to improve the clinical outcome of implantations. Generally, cartilage TE studies aim to increase the total extracellular matrix (ECM) content to improve implant mechanical properties. Besides the ECM content, however, temporal variations in deposition rate of ECM components during culture may also have an effect. Using a computational approach, the present study aims to quantify possible effects of temporal variations in the deposition of glycosaminoglycan (GAG) at given collagen synthesis rates on the mechanical stiffness of cartilage TE constructs. Maturation of a cylindrical cartilage TE construct over 42 days of culture was simulated using a composition-based finite element model that accounted for the transient deposition of GAG and collagen. Results showed an effect of GAG deposition rate on the swelling behavior and the collagen network strain, which resulted in significant changes in the compressive stiffness of cartilage TE constructs. When collagen deposition was first allowed in the constructs while the GAG deposition was delayed for the first 2 or 4 weeks, the collagen more effectively restricted tissue swelling later during the culture. Consequently, while the ultimate amount of ECM at day 42 was identical between the constructs, those with delayed GAG deposition contained elevated internal osmotic swelling pressure (up to 48%). This increased the compressive stiffness (up to 60%) of cartilage TE constructs at day 42. These findings clarify similar, yet unexplained, experimental observations. By providing further insights into mechanical effects inside cartilage TE constructs, these analyses are expected to help in designing culture regimes for engineering TE cartilage with improved load-bearing properties.

Current tufa sedimentation in a changing-slope valley: The River Añamaza (Iberian Range, NE Spain)

A three-year study of modern carbonate sedimentation was conducted through analysis of sedimentological and hydrochemical parameters measured every six months at 10 sites along a high-slope river in northeastern Spain (River Añamaza). Three stretches of the river were characterised. The dominant water inputs from the upstream karstic springs, primarily from the Jurassic rock aquifer, determined the SO4–HCO3–Ca composition of the river water. From this area, decreasing trends in alkalinity, calcium and total dissolved inorganic carbon occurred downstream in both the warm and cool periods as a result of calcite precipitation. Tufa thickness variations were consistent with such hydrochemical evolution. Deposition rates increased downstream, primarily where the gradient is steeper (middle stretch), and subsequently decreased at the downstream gently sloped stretch. Therefore, the slope along the river and the distance from the main upstream springs conditioned the spatial distribution of tufa deposits by determining the chemical characteristics of the water.The monitored sites represent four primary fluvial subenvironments with distinct sedimentary facies. The highest carbonate deposition rates were measured in fast-flow conditions (stromatolites, facies A). Deposits with calcite-coated algae and mosses (facies C) formed in cascades and small jumps with very fast-flowing water exhibited lower deposition rates and typical erosion. Lower rates corresponded to slow flow conditions in which thin stromatolite crusts and/or filamentous and calcareous algae and tufa fragments (facies B) accumulated. In slow-flowing water areas near springs (upstream stretch) calcite was absent, linked to the higher pCO2 of water; microbial films and aquatic flora composed the biofacies (facies D) in such subenvironment. Therefore, tufa deposition rates in each fluvial subenvironment were controlled by the amount of CO2 outgassing linked to local flow conditions, the biological substrate type and the chemical attributes of the water along each stretch.A six-month pattern of deposition rates, best marked in the steeper stretch, was recorded from thickness measurements (spring+summer periods=4.30mm; autumn+winter periods=1.22mm). Parallel variations were recorded using PWP (Plummer, Wigley, Parkhurst) and calcite mass balance calculations. Multivariate statistical analyses (HCA and PCA) clearly separated hydrochemical and sedimentological attributes in samples from warm and cool periods. Exceptions to this pattern were related to changes in the water discharge; high discharge events caused the dilution of the chemical composition and erosion of the tufa deposits. Therefore, temperature-dependent factors (i.e., physico-chemical and biological processes) coupled with discharge changes controlled the seasonal variations in deposition rates. The stable-isotope composition of calcite and river water also reflected the discharge effects. However, the seasonal variation signature of temperature was preserved in the δ18O of sediment.

Fly Ash Deposition during Oxy-fuel Combustion in a Bench-Scale Fluidized-Bed Combustor

Ash deposition on heat-exchanger surfaces in boiler systems can cause numerous problems, including slagging, fouling, and corrosion. These deleterious processes can be compounded if the boiler combustion process is changed from air to oxy-fuel. In this paper, fly ash deposition characteristics under both air and oxy-fuel combustion conditions were investigated using a bench-scale fluidized-bed combustor (FBC) based on measurements of ash deposition rates via a temperature-controlled probe. Three different combustion atmospheres were studied, and results demonstrated that, under similar combustion temperature profiles and equivalent fluidization velocities, the deposition rate increased when transitioning from combustion atmospheres consisting of 21% O2/79% CO2 to air to 30% O2/70% CO2. To determine the primary factors associated with the observed variations in deposition rates, the chemical compositions and micromorphologies of ash and fly ash deposits were analyzed by inductively coupled plasma–atomic emission spectrometry (ICP–AES) and scanning electron microscopy (SEM). Particulate matter with aerodynamic diameters less than 10 μm (PM10) was measured by an electrical low-pressure impactor (ELPI), and the particle size distributions (PSDs) and carbon contents of the collected filter ash were also ascertained. The results indicate that the higher deposition propensity associated with a 30% O2/70% CO2 atmosphere can be largely attributed to a wider PSD rather than any changes in the chemical compositions of the fly ash or deposited ash, in which there are no obvious differences between air and oxy-fuel combustion. In addition, the slightly higher concentration of fine particles produced under this atmosphere also promotes the deposition of fly ash.

Illuminating nonlinear dependence of film deposition rate in a CVD reactor on operating conditions

Mixed convection flow multiplicities commonly arise in CVD processes, due to the competition between free (natural) and forced convection. The instabilities and the associated solution multiplicity are due to nonlinear terms appearing in the transport equations. The stability interchange between stable and unstable steady states is marked by a pair of turning points on solution branches in parameter space; along them, two stable steady state branches are connected with an unstable one. The case study chosen is that of silicon deposition on a single wafer. To examine the phenomena inside the CVD reactor, the set of coupled transport equations along with a chemistry model for silicon deposition are solved with the commercial code Ansys/Fluent. In contrast to previous works that studied chemistry-free systems, here the effects of nonlinearities are investigated while accounting for the interplay of reaction and transport. Parameter continuation is made possible by the arc-length/RPM algorithm. The film deposition rate on the wafer is computed in every part of the solution branch at different temperature values, which are selected from the various deposition regimes of the Arrhenius plot, namely the diffusion or transport limited, the reaction limited and the transition regimes. Our results reveal multiple Arrhenius plots. In the reaction limited regime, the deposition rate variation along the wafer is similar in both dominant physical mechanisms. However, in the diffusion limited regime, the variations are different; in particular, when forced convection dominates, a significant increase of the deposition rate in the center of the wafer is observed.

Cake thickness and deposition rate variation in a plate-and-frame filter press.

Cake thickness and deposition rate variation in a plate-and-frame filter press.

Atmospheric behavior, deposition, and budget of radioactive materials from the Fukushima Daiichi nuclear power plant in March 2011

[1] To understand the atmospheric behavior of radioactive materials emitted from the Fukushima Daiichi nuclear power plant after the nuclear accident that accompanied the great Tohoku earthquake and tsunami on 11 March 2011, we simulated the transport and deposition of iodine-131 and cesium-137 using a chemical transport model. The model roughly reproduced the observed temporal and spatial variations of deposition rates over 15 Japanese prefectures (60−400 km from the plant), including Tokyo, although there were some discrepancies between the simulated and observed rates. These discrepancies were likely due to uncertainties in the simulation of emission, transport, and deposition processes in the model. A budget analysis indicated that approximately 13% of iodine-131 and 22% of cesium-137 were deposited over land in Japan, and the rest was deposited over the ocean or transported out of the model domain (700 × 700 km2). Radioactivity budgets are sensitive to temporal emission patterns. Accurate estimation of emissions to the air is important for estimation of the atmospheric behavior of radionuclides and their subsequent behavior in land water, soil, vegetation, and the ocean.