Heavy Deposition Research Articles

Numerical Simulation of Propellant Diffusion Considering Chemical Reaction

Gas phase diffusion process of UDMH and NTO in confined space was investigated and the mechanism of the reaction between the propellants was analyzed in order to study the diffusion process considering chemical reaction between propellants based on numerical simulation. According to the results of numerical simulation, the propellant concentration distribution, resultant of reaction distribution, as well as temperature distribution was obtained. Results showed that the leakage diffusion process can be divided into three stages: heavy gas deposition stage, rapid reaction stage and equilibrium diffusion stage. In the heavy gas deposition stage, propellants are mainly affected by gravity. During the rapid reaction stage, the chemical reaction between propellants plays a certain role in the diffusion process. In the equilibrium diffusion stage, the bottom temperature of the confined space increased significantly, the highest temperature reached 306K.

Survey of atmospheric heavy metal deposition in Suqian using moss contamination

Heavy metal pollution in the atmosphere is a major environmental problem, which has important impacts on ecosystems and human health. In this study, the atmospheric deposition of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in Suqian, China, was investigated by using the moss Haplocladium microphyllum as a bioindicator. The survey was carried out during the summer of 2017 at 40 homogenously distributed sampling sites. Cr, Cu, Ni, Pb, V, and Zn were analyzed by inductively coupled plasma atomic emission spectrometry, and Cd was analyzed by inductively coupled plasma mass spectrometry. Wide variations in heavy metals (Cd, Pb, and Zn) indicated that the concentrations of elements are influenced by local emission sources. Spatial distribution maps of the elements were constructed using geographic information system technology. The pollution load index showed that the study area was moderately polluted to unpolluted. Significant positive correlations (p < .01) and weak positive correlations (p < .05) were identified among some of the elements, indicating that they originated from common sources. A principal component analysis classified the heavy metals into natural and anthropogenic sources, and identified four primary sources: nature soil dust, industry activities, traffic emission, and agricultural activities.

Nickel Supported on AlCeO3 as a Highly Selective and Stable Catalyst for Hydrogen Production via the Glycerol Steam Reforming Reaction

In this study, a critical comparison between two low metal (Ni) loading catalysts is presented, namely Ni/Al2O3 and Ni/AlCeO3 for the glycerol steam reforming (GSR) reaction. The surface and bulk properties of the catalysts were evaluated using a plethora of techniques, such as N2 adsorption/desorption, Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP–AES), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDX, Transmission Electron Microscopy (TEM), CO2 and NH3– Temperature Programmed Desorption (TPD), and Temperature Programmed Reduction (H2–TPR). Carbon deposited on the catalyst’s surfaces was probed using Temperature Programmed Oxidation (TPO), SEM, and TEM. It is demonstrated that Ce-modification of Al2O3 induces an increase of the surface basicity and Ni dispersion. These features lead to a higher conversion of glycerol to gaseous products (60% to 80%), particularly H2 and CO2, enhancement of WGS reaction, and a higher resistance to coke deposition. Allyl alcohol was found to be the main liquid product for the Ni/AlCeO3 catalyst, the production of which ceases over 700 °C. It is also highly significant that the Ni/AlCeO3 catalyst demonstrated stable values for H2 yield (2.9–2.3) and selectivity (89–81%), in addition to CO2 (75–67%) and CO (23–29%) selectivity during a (20 h) long time-on-stream study. Following the reaction, SEM/EDX and TEM analysis showed heavy coke deposition over the Ni/Al2O3 catalyst, whereas for the Ni/AlCeO3 catalyst TPO studies showed the formation of more defective coke, the latter being more easily oxidized.

Spatial distribution and controlling factors of heavy metals in soils from Puding Karst Critical Zone Observatory, southwest China

Soil profile samples under different land-use types were collected at the Puding Karst Critical Zone Observatory to investigate the composition, distribution and controlling factors of heavy metals. The heavy metal contents of Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb were determined, and their relationships to soil properties were examined. The Mn, Zn, Cd and Pb contents were larger in the topsoil than the deeper layer in all land use. In secondary forest land, the Cr, Fe, Ni and Cu contents in the topsoil were lower than in the deeper layer; however, all eight heavy metal contents were enriched in the topsoil under cropland. The results showed soil organic carbon played a fundamental role in controlling of Cd, while it showed negative relationship with Cr, Fe, Ni and Cu. Soil pH was positively associated with Ni and Cu. The Cr, Fe, Ni and Cu contents were significantly correlated to proportion of micro-aggregates, while the Cd and Pb contents showed a positive correlation with proportion of macro-aggregates. According to principal component analysis, the Cr, Fe, Ni and Cu contents might be affected by soil organic matter; however, the Mn, Zn and Pb contents might be influenced by atmospheric heavy metal deposition, and the Cd content might be controlled by both organic matter and atmospheric deposition. The geoaccumulation index and enrichment factor were calculated to assess the pollution level of soils, and the results showed that most of the selected heavy metals in soils may not be present at sufficient levels for contamination, and Mn and Fe were not from a pollution source and might come from natural weathering processes. This research will help researchers make strategic decisions about food security in the choice of agricultural land.

Global modeling of wall material migration following boronization in NSTX-U

Abstract Boronization is commonly utilized in tokamaks to suppress intrinsic impurities, most notably oxygen from residual water vapor. However, this is a temporary solution, as oxygen levels typically return to pre-boronization levels following repeated plasma exposure. The global impurity migration model WallDYN has been applied to the post-boronization surface impurity evolution in NSTX-U. A “Thin Film Model” has been incorporated into WallDYN to handle spatially inhomogeneous conditioning films of varying thicknesses, together with an empirical boron conditioning model for the NSTX-U glow discharge boronization process. The model qualitatively reproduces the spatial distribution of boron in the NSTX-U vessel, the spatially-resolved divertor emission pattern, and the increase in oxygen levels following boronization. The simulations suggest that oxygen is primarily sourced from wall locations without heavy plasma flux or significant boron deposition, namely the lower and upper passive plates and the lower private flux zone.

Synthesis of ZnO Nanoparticles for Wax Deposition Control and Oil Upgrading: Effect of Ratio of Zinc Acetate Dihydrate to Oxalic Acid Dihydrate

In the current paper, fundamental aspects of heavy oil and wax deposition problems are defined. Wax or in another term is cloud point occur when the oil starts to precipitate. When it’s started to precipitate, it can cause major problem to industry of oil and gas. In this study, ZnO nanoparticles were chosen to study the effect of varying molar ratio from 1:1, 1:2, 1:3 to the morphology and size of the nanoparticle. The structures and properties were recognized with energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD) methods. EDX and FE-SEM is to study the morphology of ZnO structure while XRD is to determine the purity and size of the nanoparticle. From the study, 1:1 ratio has the smallest size of nanoparticle with 10.37 nm while 1:2 and 1:3 give the size of 12.3 nm and 16.37 nm respectively. As the molar ratio is increases, the size of nanoparticle become bigger. The influenced of ZnO nanoparticles on rheological behaviour of model oils and the wax content is reported. From the study, the addition of ZnO nanoparticle reduced the rheology behaviour of crude oil by varying nanoparticle sizes, temperature and shear rate. ZnO nanoparticle can reduce the deposition of wax up to 50% with influenced of smaller nanoparticle size. Effect of size of nanoparticle highly impact the viscosity and wax content. This prove that, by introducing nanoparticle into crude oil, wax content can be reduced thus decrease the chance for crude to precipitate.

Immutable heavy metal pollution before and after change in industrial waste treatment procedure

This study compared state of pollution around an intermediate treatment plant of industrial wastes before and after the change of its treatment procedure. Bulk atmospheric deposition, surface soil, suspended particulate matter and groundwater were collected after the plant changed main operation to waste crushing and volume reduction. Their heavy metals content were comparatively investigated with the previous results obtained when it was burning wastes. The bulk heavy metals deposition showed a clear distance-related attenuation both in burning and crushing periods, indicating that the plant was the main emissions source in either case. High concentrations of heavy metals in suspended particles, soil, and groundwater during the crushing period indicated their diffusion to water environment over time. The bulk atmospheric heavy metals deposition decreased significantly, 0.20~ 0.49 times for Cu, Zn, Cd and Pb and 0.69~0.94 times for Cr, during the crushing period than burning period. However, change of their enrichment factors was not significant. It may indicate that the pollution state did not change qualitatively in a bulk deposition basis and quantitatively in a depositing particle basis. The results showed that heavy metals deposition is dominated by suspended and precipitated particulate matters that adsorb and transport the metals.

Laser treatment of hyperpigmented lesions: position statement of the European Society of Laser in Dermatology.

Lasers and intense pulsed light sources (IPLS) are proposed for the treatment of many pigmentary disorders. They are sometimes considered as magic tools able to remove any type of lesions. Although being the best option for several hyperpigmented lesions, they can also worsen some conditions and have potential side-effects. The aim of this review was to give evidence-based recommendations for the use of lasers and IPLS in the treatment of hyperpigmented lesions. These recommendations were produced for the European Society of Laser Dermatology by a consensus panel made up of experts in the field of pigment laser surgery. Recommendations on the use of lasers and light treatments were made based on the quality of evidence for efficacy, safety, tolerability, cosmetic outcome, patient satisfaction/preference and, where appropriate, on the experts' opinion. Lasers and IPLS are very effective for treating many hyperpigmented lesions such as lentigos, dermal hypermelanocytosis or heavy metal depositions. In the other hand, they have to be considered with great caution for other disorders, such as café au lait macules, melasma or postinflammatory hyperpigmentation. After making the correct diagnosis, if lasers or IPLS are indicated, the optimal wavelengths and parameters will be chosen taking into account the skin phototype, origin and depth of the target pigments. Although potentially very effective, lasers and IPLS cannot be proposed for all types of hyperpigmented lesions. In all cases, precise recognition of the disorder is mandatory for choosing between these devices and other therapeutic approaches.

Structure Changes in Carbon Films Prepared by Electron-Beam-Assisted Deposition

Carbon films 50–180 nm thick on nickel substrates are fabricated by the ion sputtering of graphite and the deposition of heavy hydrocarbons from the gas phase with simultaneous electron irradiation. Irradiation results in the formation of bonds in carbon films due to the sp and sp3 hybridization of orbitals (sp and sp3 bonds), mainly, sp3 bonds. A fraction of these bonds does not change with growth in the electron energy; it increases three-fold with a reduction in the temperature and an increase in the electron current density. Electron irradiation enhances the film microhardness which exceeds 12 GPa. The films, prepared by heavy hydrocarbon deposition, contain CHn bonds and a small fraction of sp3 bonds. The maximum value of the microhardness of the hydrocarbon films is no more than 4.5 GPa. The analysis of the proposed model of the kinetics of forming different allotropic phases in a carbon film to be deposited shows that a temperature reduction changes the specific volume of an atom in the lattice, while under conditions of simultaneous electron irradiation, it appreciably increases the content of the phase with sp3 bonds. The effect of spi-bond breakage during electron-beam-assisted deposition weakly depends on the electron energy. The weak excitations of electrons of carbon atoms can also result in the formation of sp3 bonds and increases their concentration with growth in the electron current density.

Lichens and Bromeliads as Bioindicators of Heavy Metal Deposition in Ecuador

We evaluated heavy metal deposition in Parmotrema arnoldii and Tillandsia usneoides in response to air pollution in Loja city, Ecuador. We assessed heavy metal (cadmium, copper, manganese, lead and zinc) content in these organisms at nine study sites inside Loja city and three control sites in nearby forests. Concentrations of all studied heavy metals (i.e., cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn) and zinc (Zn)) were highest in downtown Loja. Our study confirms that passive monitoring using lichens and/or bromeliads can be an efficient tool to evaluate heavy metal deposition related to urbanization (e.g., vehicle emissions). We recommend these organisms to be used in cost-effective monitoring of air pollution in tropical countries.

Cadmium concentrations in German soybeans are elevated in conurbations and in regions dominated by mining and the metal industry.

Cadmium (Cd) is a mobile heavy metal and soybeans accumulate more of this element compared to other grain crops. Because vegan and vegetarian lifestyles are increasingly popular, plant-based diets should be free from contaminants. Cd minimization has recently been identified as a breeding aim in addition to protein and oil levels. It is also important to consider the regional variability of Cd in crops. A large sample collection (n = 602) was subjected to Cd analyses. Soybeans were grown using a standard protocol by private gardeners in a citizen science program. Some 12.5% of samples exceeded European Union limits, although Cd concentrations and exceedances showed regional variation around the national mean (0.13 mg kg-1 ). Contamination was higher in densely populated regions, possibly as a result of the long-term emissions of heavy metal loaded dusts from industry, traffic and energy production. Cd concentrations were also elevated in regions once characterized by mining and heavy industry. Values were low overall in rural areas and agricultural regions despite potential inputs via phosphate fertilizers. Grain Cd levels are highly variable across Germany. Soybean farming may be problematic in regions with a long history of mining and heavy metal deposition. © 2018 Society of Chemical Industry.

A durability study of a compression ignition engine operating with Thumba (Citrullus colocyntis) vegetable oil.

Vegetable oils are found suitable alternate of diesel fuel as per the results of short-run studies. Long-run studies with vegetable oil as a fuel pointed out the problems related to wear and maintenance of the engine. A single cylinder, variable compression ratio diesel engine was tested for 512 h (32 cycles of 16 h per day) to investigate longevity implications of fueling Thumba vegetable oil. Results of the study revealed that a very little damage was observed over the running surface of the cylinder liner, piston rings, valves, and valve seats. Wear in the piston outer diameter was observed to be 13 to 30 microns. Cylinder wear was about 80 microns. The closed gap in the oil piston ring increased up to 200 microns. Heavy carbon deposition was found on different internal parts of the engine, which indicates poor combustion of fuel. Amount of copper (66 mg/kg) and silicon (112 mg/kg) dissolved in the lubricating oil was found more than permissible limits (Cu 50 mg/kg, Si 25 mg/kg), after 450-h engine test run. But all the dissolve materials remain in allowable limits when the durability test conducted with diesel. Smoke, CO, HC, and NOX emissions were found to increase initially then decrease in the further engine running hours. But these emissions were found inferior to the engine emissions fueled with diesel in all the running hours. CO2 emissions were found superior throughout the test with the preheated T20 Thumba oil blend than diesel. The maximum reduction in the viscosity of the lubricating oil, during endurance testing, was found 60 centipoises but it was found 25 centipoises when the test conducted with diesel.

Railroad derived nitrogen and heavy metal pollution does not affect nitrogen fixation associated with mosses and lichens at a tundra site in Northern Sweden

Traffic derived nitrogen (N) and heavy metal pollution is a well-known phenomenon, but little explored in otherwise pristine ecosystems such as subarctic tundra. Here, the main source of N input to the ecosystem is via N2 fixation by moss- and lichen-associated bacteria. While inhibitory effects of N deposition on moss-associated N2 fixation have been reported, we still lack understanding of the effects of traffic derived N and heavy metal deposition on this ecosystem function in an otherwise pristine setting. To test this, we established a distance gradient (0–1280 m) away from a metal pollution source -a railway transporting iron ore that passes through a subarctic birch forest. We assessed the effects of railway-derived pollution on N2 fixation associated with two moss species Pleurozium schreberi, Hylocomium splendens and with the lichen Peltigera aphthosa. Deposition and availability of N and heavy metals (Fe, Cu, Zn, Pb) as well as the respective contents in moss, lichen and soil was assessed. While we found a steep gradient in metal concentration in moss, lichen and soil with distance away from the pollution source, N deposition did not change, and with that, we could not detect a distance gradient in moss- or lichen-associated N2 fixation. Hence, our results indicate that N2 fixing bacteria are either not inhibited by heavy metal deposition, or that they are protected within the moss carpet and lichen tissue.

Successful treatment of gamma 1 heavy chain deposition disease with bortezomib and dexamethasone

Heavy chain deposition disease (HCDD) is a rare complication of plasma cell dyscrasias, characterized by nonamyloid tissue deposits of incomplete monoclonal heavy chains in renal tissues. We report the case of a 78-year-old female with HCDD who was successfully treated with bortezomib and dexamethasone (BD); histopathological improvements were confirmed by kidney biopsy after 2 years of chemotherapy. She presented with renal insufficiency, proteinuria, hematuria, hypogammaglobulinemia, and hypocomplementemia. Renal biopsy showed diffuse global nodular glomerulopathy with the deposition of IgG1 and C3 in the glomeruli and on the tubular basement membrane. Kappa and lambda light chains were not detected. Staining for the constant regions of the gamma heavy chain revealed the absence of the CH1 domain. These findings are consistent with those of gamma 1 HCDD. Results of liquid chromatography-tandem mass spectrometric analysis were consistent with the immunohistochemical results. Two years after weekly BD therapy, normalization of the kappa/lambda ratio and reduction of urinary protein excretion were achieved. A follow-up biopsy showed remarkable diminution of nodular lesions of glomeruli and deposits of IgG and C3.

Use of tree rings as a bioindicator to observe atmospheric heavy metal deposition.

Trees can be used as good indicators to evaluate the increase in atmospheric heavy metal concentrations. In the last two decades, air pollution in the city of Ankara has rapidly increased with the ever-increasing traffic density. In the present study, the depositions of aluminum (Al), zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), manganese (Mn), chrome (Cr), cadmium (Cd), sodium (Na), calcium (Ca), barium (Ba), phosphor (P), magnesium (Mg), arsenic (As), and boron (B) in the rings of oak trees were analyzed using a GBC Integra XL-SDS-270 ICP-OES device. The study found that heavy metal concentrations in tree rings varied over the past 20years; furthermore, there was a significant relationship between the heavy metal concentrations in tree rings and the atmospheric heavy metal concentrations. There was an increase in the concentrations of nutritional elements (Na, P, and Mg) in 2010 when there was excessive precipitation. As a result, the concentrations of all elements in the woods of different ages were significantly different at a confidence interval of 95% for As, 99% for Cd, and 99.9% for other elements.

Heavy chain disease: a rare case report of adult nephrotic syndrome

Monoclonal immunoglobulin deposition disease is a systemic disorder characterized by the deposition of immunoglobulins as nonfibrillar material in various organs. Three subtypes have been reported: light chain deposition disease, light and heavy chain deposition disease and heavy chain deposition disease. Among these, light chain deposition disease is the most prevalent. Reports of light and heavy chain and heavy chain disease are rare, with fewer than two dozen documented cases in the world literature and very few from India. Heavy chain disease is characterized by glomerular, tubular, and vascular wall deposition of monoclonal heavy chains without associated light chains. We present the case of a 51-year man, who presented with a 3-month history of pedal edema, hypertension detected 3 months ago, and mild renal failure Estimated Glomerular filteration rate (eGFR) 66 ml/min/1.73 m2; histopathology showed heavy chain deposition disease. The case emphasizes the need for a thorough workup for plasma cell dyscrasias when we see membranoproliferative pattern in adult patients. This patient was treated with bortezomib-based regimen and after 3 months achieved near-complete remission of proteinuria with improvement in serum creatinine.

Light and heavy chain deposition revealed by repeat renal biopsy after inconclusive initial biopsy

Monoclonal gammopathy is a premalignant condition associated with an abnormal circulating immunoglobulin indicative of an expanded B cell clone. Apart from monitoring, no other intensive management is prescribed in these cases. Periodic bone marrow biopsies when free light chain imbalances are detected are used to spot incidental cases of multiple myeloma. New reports have suggested the existence of a monoclonal gammopathy of renal significance where a circulating antibody and normal bone marrow biopsy results may be associated with proteinuric renal disease due to monoclonal immunoglobulin deposition. We report a case of a 65-year-old male with an immunoglobulin G kappa monoclonal gammopathy of undetermined significance, chronic kidney disease, proteinuria, and an initial inconclusive renal biopsy. His chronic kidney disease worsened with persistence of 0.5 g of proteinuria. Given the finding of ongoing Bence Jones proteinuria, a repeat renal biopsy was done revealing monoclonal immunoglobulin G kappa deposition disease. Bone marrow biopsy showed 20% plasma cells that could be consistent with smoldering myeloma. The patient’s renal disease has stabilized after starting treatment for the monoclonal gammopathy of renal significance. This case illustrates the importance of renal biopsy in making the diagnosis of monoclonal immune deposition disease and monoclonal gammopathy of renal significance.

Utilization of Bio-Syngas in Solid Oxide Fuel Cell Stacks: Effect of Hydrocarbon Reforming

We report on state-of-the-art JÜLICH (Forschungszentrum Jülich) stack with anode-supported solid oxide fuel cells (AS-SOFCs) that have been tested in bio-syngas derived from wood pellets. The sulfur and chlorine were removed after gasification, but the tars were not reformed in the bio-syngas to study the influence of these tars on the degradation of SOFC stack. The total tar content during test was 3.5 g/Nm3 including benzene, toluene, phenol, m-cresol, naphthalene, and minor traces of undefined tars. The test result shows considerable performance degradation in tar-contaminated syngas. Moreover, the test was stopped after 5 hours of operation due to an increase of the pressure drop in the stack. A post-test analysis was carried out, and heavy carbon deposition was found at the cell anode-support surface and the Ni mesh current collector. Carbon was identified by SEM as numerous carbon fibers. The change of support microstructure was also observed near and under the carbon deposition area, and the dusting of Ni metal was observed in the support and Ni mesh current collector.

Influence of heavy alkali post deposition treatment on wide gap Cu(In,Ga)Se2

The effect of Potassium, Rubidium, and Cesium post deposition treatment (PDT) on wide bandgap Cu(In,Ga)Se2 (CIGSe) absorbers has been investigated. The results show that the efficiency of the cells can be improved by the alkali treatment and a higher value of the open-circuit-voltage (VOC) can be achieved. In spite of this improvement, the activation energy (EA) of the treated samples remained smaller than the bandgap (Eg) and VOC(t) transients under red light showed a negative slope. Hence, the wide gap CIGSe devices remain limited by recombination at the interface. However, the VOC(t)-transient of treated and untreated samples with the same Eg show a different slope (d ΔVOC(t)/dt). CIGSe samples treated with heavy alkalis (RbF- and CsF-PDT) illustrate a smaller slope in comparison to no-PDT and KF-PDT samples. In this contribution, we discuss the Voc(t) slope, i.e. d ΔVOC(t)/dt, with reference to the illumination dependent doping density (NA,a) and to a possible Sodium exchange mechanisms.

Effect of Heavy Metals Contamination from Cigarette Smoke on Sound and Caries-Like Enamel.

In this study, we sought to evaluate the influence of cigarette smoke and pH cycling on the chemical composition and surface/cross-sectional enamel microhardness. A total of 40 dental blocks obtained from bovine incisors were divided into four groups (n=10): no treatment (control); exposure to cigarette smoke (CS); exposure to pH cycling (PC); and exposure to cigarette smoke and pH cycling (CS-PC). The samples were analyzed by synchrotron radiation micro X-ray fluorescence, bench mode X-ray fluorescence, as well as surface microhardness (SMH) and cross-sectional microhardness (CSMH) testing. The SMH results were submitted to analysis of variance (ANOVA) and Tukey's test. The CSMH results were evaluated using split-plot ANOVA and Tukey's test. A high amount of Cd and Pb and traces of Ni and As were observed in enamel and dentin after exposure to cigarette smoke (CS and CS-PC). The SMH and CSMH of CS were statistically higher when compared with the control. The PC and CS-PC showed lower SMH and CSMH. We conclude that exposure to cigarette smoke promoted heavy metal deposition in enamel/dentin. In addition, it increased the enamel microhardness but did not promote a protective effect on the in vitro development of caries. The clinical significance of this work is that there is significant bioaccumulation of heavy metals from cigarette smoke on the surface and in the enamel and dentin.