Journal articles: 'Seam contamination'

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Nehls, T., G. Jozefaciuk, Z. Sokolowska, M. Hajnos, and G. Wessolek. "Filter properties of seam material from paved urban soils." Hydrology and Earth System Sciences 12, no. 2 (2008): 691–702. http://dx.doi.org/10.5194/hess-12-691-2008.

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Abstract. Depositions of all kinds of urban dirt and dust including anthropogenic organic substances like soot change the filter properties of the seam filling material of pervious pavements and lead to the formation of a new soil substrate called seam material. In this study, the impact of the particular urban form of organic matter (OM) on the seam materials CECpot, the specific surface area (As), the surface charge density (SCD), the adsorption energies (Ea) and the adsorption of Cd and Pb were assessed. The Cd and Pb displacement through the pavement system has been simulated in order to assess the risk of soil and groundwater contamination from infiltration of rainwater in paved urban soils. As, Ea and SCD derived from water vapor adsorption isotherms, CECpot, Pb and Cd adsorption isotherms where analyzed from adsorption experiments. The seam material is characterized by a darker munsell-color and a higher Corg (12 to 48g kg-1) compared to the original seam filling. Although, the increased Corg leads to higher As (16m2g-1) and higher CECpot (0.7 to 4.8cmolckg-1), with 78cmolckg-1C its specific CECpot is low compared to OM of non-urban soils. This can be explained by a low SCD of 1.2×10-6molc m-2 and a low fraction of high adsorption energy sites which is likely caused by the non-polar character of the accumulated urban OM in the seam material. The seam material shows stronger sorption of Pb and Cd compared to the original construction sand. The retardation capacity of seam material for Pb is similar, for Cd it is much smaller compared to natural sandy soils with similar Corg concentrations. The simulated long term displacement scenarios for a street in Berlin do not indicate an acute contamination risk for Pb . For Cd the infiltration from puddles can lead to a breakthrough of Cd through the pavement system during only one decade. Although they contain contaminations itself, the accumulated forms of urban OM lead to improved filter properties of the seam material and may retard contaminations more effectively than the originally used construction sand.

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Su, Xianbo, Fengde Zhou, and Stephen Tyson. "Numerical investigation of the potential contamination of a shallow aquifer in producing coalbed methane." Energy Exploration & Exploitation 36, no. 2 (2017): 282–96. http://dx.doi.org/10.1177/0144598717736629.

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This paper presents a study on the impact of well integrity failure on coalbed methane (also known as coal seam gas) production and potential shallow water contamination using numerical simulations with a finite-difference method. Two connection types and 12 cases were simulated: Type A – leakage through cement sheath and Type B – impaired zonal isolation at the aquifer interval. The effect of the distance between the aquifer and the coal seam, drainage area and desorption time on gas and water production was also inspected. Results show that both connection types have strong effects on the gas and water production; the cumulative water and gas production increases with increasing drainage radius; the distance between aquifer and the coal seam has a negative effect on the water production but a negligible effect on the gas production; desorption time, ranging from 5 to 30 days, has a negligible effect on the water and gas production. Connection Type A yields a potential water contamination but connection Type B does not. Gas concentration in the shallow aquifer decreases sharply with an increase of distance away from the producer and the unsafe area are within an area with a radius ranging from approximately 50 m to 90 m away from the producer in this study.

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Nehls, T., G. Jozefaciuk, Z. Sokolowska, M. Hajnos, and G. Wessolek. "Filter properties of seam material from paved urban soils." Hydrology and Earth System Sciences Discussions 4, no. 4 (2007): 2625–57. http://dx.doi.org/10.5194/hessd-4-2625-2007.

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Abstract. We studied pavement seam material. This is the soil substrate in joints of pervious pavements in urban areas. It is mostly 1 cm thick and develops from the original seam filling by depositions of all kinds of urban residues, including anthropogenic organic substances. It was investigated, how this unique form of organic matter influences the filter properties of seam material and how the seam material influences heavy metal transport through the pavement. The seam material is characterised by a darker munsell colour, higher organic carbon content, higher surface areas, higher cation exchange capacities, but a lower fraction of high adsorption energy sites compared to the original seam filling. The deposited anthropogenic organic matter itself could be characterised as particulate and non-polar. Compared to natural soils, it has a small surface area and a low surface charge density resulting in a small cation exchange capacity of only 75 cmol(+) kg−1C. The seam material shows stronger sorption of Pb and Cd compared to the original construction sand. The retardation capacity of seam material towards Pb is similar, towards Cd it is much smaller compared to natural soils. The simulated long term displacement scenarios for a street in Berlin do not indicate an acute contamination risk for Pb. For Cd the infiltration from ponds can lead to a displacement of Cd during only one decade.

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Blankl, A., and Manfred Geiger. "Investigations on Seam Quality in Laser Beam Welding of Contaminated, Zinc Coated Sheets." Advanced Materials Research 6-8 (May 2005): 187–94. http://dx.doi.org/10.4028/www.scientific.net/amr.6-8.187.

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The customers’ demand for high quality and low cost products with rising functionality forces the enterprises to cost savings. In production these cost savings can be accomplished by simplification or omission of handling operations in the process chain. In laser beam welding of stamped sheet metals a previous cleaning of the sheets is usually necessary to guarantee a sufficient seam quality at a lap joint. Due to the recent trend towards low use of lubricants in forming operations the question arises, whether this process could be avoided in order to lower the production costs. The disadvantage of this measure would be a degradation of the seam quality. This reduction shows up in a falling strength of the weld due to inclusions and pore formation. This paper deals with the impact of different types of contaminations on the quality of laser welding. Therefore several liquid (oils) and solid (metallic and non-metallic) contaminants are examined. Zinc coated sheets are investigated too, because a zinc contamination arises with these sheets in the welding operation. The zinc coating evaporates because of the high temperature and this leads to a high porosity in the welding seam. In both cases also the height of the gap between the two sheets is varied in order to investigate its influence on the weld. To reduce the effort of the investigations, but not the accuracy of the results, the laboratory trials were supported by the methods of design of experiments. After the welding operation, the quality of the welding seam is evaluated by means of its mechanical properties and tightness. The results of the investigations are discussed and the developed solution strategies are presented.

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Gonzalez, Dennis, Sreekanth Janardhanan, Daniel E. Pagendam, and Daniel W. Gladish. "Probabilistic Groundwater Flow, Particle Tracking and Uncertainty Analysis for Environmental Receptor Vulnerability Assessment of a Coal Seam Gas Project." Water 12, no. 11 (2020): 3177. http://dx.doi.org/10.3390/w12113177.

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The production of coalbed methane, or coal seam gas (CSG) in Australia increased 250-fold since the 1990s to around 1502 petajoules in 2019 and continues to expand. Groundwater flow in the aquifers intersected by gas wells could potentially facilitate a transport pathway for migration of contaminants or poorer quality water from deeper formations. While regulatory and mitigation mechanisms are put in place to minimize the risks, quantitative environmental impact assessments are also undertaken. When many gas wells are drilled in a wide area where many potential receptors are also spatially distributed, potential source-receptor combinations are too numerous to undertake detailed contamination risk assessment using contaminant transport modelling. However, valuable information can be gleaned from the analysis of groundwater flow directions and velocities to inform and prioritise contamination risk assessment and can precede computationally challenging stochastic contaminant transport modelling. A probabilistic particle tracking approach was developed as a computationally efficient screening analysis of contamination pathways for a planned CSG development near Narrabri in northern New South Wales, Australia. Particle tracking was run iteratively with a numerical groundwater flow model across a range of plausible parameter sets to generate an ensemble of estimated flow paths through the main Great Artesian Basin aquifer in the area. Spatial patterns of path lines and spatial relationships with potential receptors including neighbouring groundwater extraction wells and hydrologically connected ecological systems were analysed. Particle velocities ranged from 0.5 to 11 m/year and trajectories indicated dedicated contaminant transport modeling would be ideally focused at the local scale where wells are near potential receptors. The results of this type of analysis can inform the design of monitoring strategies and direct new data collection to reduce uncertainty and improve the effectiveness of adaptive management strategies and early detection of impacts.

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Li, Shaodong, Gangwei Fan, Dongsheng Zhang, et al. "Fracture Propagation and Hydraulic Properties of a Coal Floor Subjected to Thick-Seam Longwalling above a Highly Confined Aquifer." Geofluids 2021 (July 2, 2021): 1–12. http://dx.doi.org/10.1155/2021/6668644.

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The high-pressure and water-rich confined aquifer occurring in the Ordovician limestone sequence poses great threats to the routine production of underground longwall mining. Considering the intense cooperation of mining disturbance and water pressure, water-conducting fractures within a coal seam floor can connect the lower aquifer and upper goaf, and this hydraulic behavior is considered the root of water inrush hazard and water loss or contamination. In this paper, the panel 4301 of the Longquan coal mine serves as the case where the panel works closely above the floor with high water pressure. By the combination of physical and numerical modelling approaches, the variation characteristics of fracture development and volumetric strain of floor rocks subjected to mining disturbance are analyzed. A numerical computation model is constructed based on the volumetric strain-permeability equation obtained by curve fitting, and on such basis, the impacts of different mining parameters on floor rock permeability are studied. The results show that the floor rocks experience fracture generation, extension, and convergence procedures as the workface advances along the longitudinal direction, and fractures appearing in front of the workface are more developed. In the whole process of coal seam extraction, the volumetric strain profile exhibits “Λ” shape and an inverted saddle shape before and after overburden strata collapse. By controlling a single variable, the paper reveals that panel height is of greater impact on floor permeability changes than panel length and panel width.

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Smoliński, Adam, Krzysztof Stańczyk, Krzysztof Kapusta, and Natalia Howaniec. "Analysis of the organic contaminants in the condensate produced in the in situ underground coal gasification process." Water Science and Technology 67, no. 3 (2013): 644–50. http://dx.doi.org/10.2166/wst.2012.558.

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Addressing the environmental risks related to contamination of groundwater with the phenolics, benzene, toluene, ethyl benzene, xylene (BTEX) and polycyclic aromatic hydrocarbons (PAHs), which might be potentially released from the underground coal gasification (UCG) under adverse hydrogeological and/or operational conditions, is crucial in terms of wider implementation of the process. The aim of this study was to determine the main organic pollutants present in the process condensate generated during the UCG trial performed on hard coal seam in the Experimental Mine ‘Barbara’, Poland; 8,933 L of condensate was produced in 813 h of experiment duration (including 456 h of the post-process stage) with average phenolics, BTEX and PAH concentrations of 576,000, 42.3 and 1,400.5 μg/L, respectively. The Hierarchical Clustering Analysis was used to explore the differences and similarities between the samples. The sample collected during the first 48 h of the process duration was characterized by the lowest phenanthrene, anthracene, fluoranthene and pyrene contents, high xylene content and the highest concentrations of phenolics, benzene, toluene and ethyl benzene. The samples collected during the stable operation of the UCG process were characterized by higher concentrations of naphthalene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, while in the samples acquired in the post-process stage the lowest concentrations of benzene, toluene, naphthalene, acenaphthene and fluorene were observed.

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Mironov, O. G. "Biological Problems of Oil Contamination of Seas." Hydrobiological Journal 37, no. 4 (2001): 16. http://dx.doi.org/10.1615/hydrobj.v37.i4.50.

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KUPLULU, O., G. IPLIKCIOGLU CIL, S. D. KORKMAZ, O. AYKUT, and G. OZANSOY. "Determination of Metal Contamination in Seafood from the Black, Marmara, Aegean and Mediterranean Sea Metal Contamination in Seafood." Journal of the Hellenic Veterinary Medical Society 69, no. 1 (2018): 749. http://dx.doi.org/10.12681/jhvms.16400.

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Seafood is one of the most important components of a healthy diet due to its composition. With the Black, Marmara, Aegean and Mediterranean Sea, Turkey has substantial sources of seafood. Seas are highly impacted by environmental pollution. Among these, heavy metal pollution has long been recognized as a serious problem for seafood. As heavy metals cannot be degraded, they are deposited, assimilated or incorporated in water, sediment and aquatic animals. By these properties, they can be transferred to humans through the food chain especially by the consumption of fish and shellfish. The aim of this study is to determine the concentrations of Cd, As, Pb and Hg levels in selected fish species and marine animals from all of the 4 seas of Turkey by using the ICP-MS technique, and to compare the results with the legislations safe limits. For this purpose, 13 different fish species, mussels and shrimps have been obtained from the Black, Marmara, Aegean and Mediterranean Seas. According to the results, metal concentrations decrease in the order As>Pb>Hg>Cd. In all the seas, the same order was found. Statistically significant differences were observed in the metal levels between fish species and the shellfish in all regions. Except for the two samples, all the results was found compatible with the Turkish Food Codex and European Commission Regulation limits. Arsenic levels were detected between 0,076-4,230 mg/kg within the samples. Cadmium levels were detected as higher than the limits in two samples obtained from the Mediterranean Sea, Scophthalmus maximus and Mullus barbatus species as 0,076 mg/kg and 0,064 mg/kg, respectively. The highest and the lowest levels of mercury and lead were measured as 0,005-0,405 and 0,015-0,405 mg/kg, respectively. The results obtained from this study revealed that, except for a few cases, the selected heavy metal concentrations in most samples were below the limits. Also, besides the mussels and the shrimps, there was no single type of fish that was consistently high in all metals. The examined seas and the seafood were found to be safe for human consumption.

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Hildebrandt, Manuel, Corina Schwitzke, and Hans-Jörg Bauer. "Contamination of Brush Seals by Oil and Salt and Its Impact on Rubbing and Hysteresis Behaviour." International Journal of Turbomachinery, Propulsion and Power 4, no. 4 (2019): 40. http://dx.doi.org/10.3390/ijtpp4040040.

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The literature already contains some experimental, analytical and numerical investigations on the rubbing and hysteresis behaviour of brush seals. What the investigations have in common is that they were carried out with new and uncontaminated seals, or that such a condition was assumed. The influence of contamination has not been explicitly investigated yet. Particularly in stationary gas and steam turbines, foreign substances can accumulate on and in the bristle package during steady-state operation. In the case of a rubbing event with a contaminated brush seal, e.g., during shutdown of the machine, the process is not expected to be comparable to that assumed in the presence of a new, uncontaminated seal. The present paper is dedicated to the question of the influence of contamination on the total frictional power loss generated during rubbing and the distribution of heat fluxes in friction contact. For this purpose, rub tests with two seals were carried out on the brush seal test rig of the Institute of Thermal Turbomachinery (ITS) in new conditions. Subsequently, the sealing packages were contaminated with oil or a salt mixture. After the treatment, the rub tests were repeated and compared with the previous tests. In addition, stiffness measurements were used to assess the degree of contamination. A strong influence on the rubbing behaviour by the contamination was detected. Contamination causes the flexibility of the bristle package to be greatly reduced. As a result, especially at the beginning of the first measurements, the total power losses and rotor heat inputs are strongly increased. This flexibility is partly regained in the course of the measurements. As expected, contamination also influences the hysteresis behaviour of the seal. A highly increased leakage rate after rubbing could be observed, because the bristles remained close to their deflected positions. In the case of the salted seal, however, an improvement in the leakage performance could be observed after several repeat tests.

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Amlani, Harsh. "Microleakage: Apical Seal vs Coronal Seal." World Journal of Dentistry 4, no. 2 (2013): 113–16. http://dx.doi.org/10.5005/jp-journals-10015-1215.

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ABSTRACT Microorganisms can reach the dental pulp through the open cavity, dentinal tubules, gingival sulcus, periodontal ligament through a broken occlusal seal or faulty restoration of tooth previously treated by endodontic therapy or extension of a periapical infection from adjacent infected teeth. During operative procedures, these possible paths must be considered to prevent ingress. While endodontic therapy is being performed, these paths must be blocked to avoid contamination during and after the treatment. Well treated tooth might also fail if microorganisms reach the periradicular tissues. After root canal obliteration, care must be taken to ensure maintenance of the coronal as well as apical seal from contaminants. How to cite this article Amlani H, Hegde V. Microleakage: Apical Seal vs Coronal Seal. World J Dent 2013;4(2):113-116.

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Farrant, J. L., and E. Bez. "Oil-Free Forepumps for Electron Microscopes." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (1990): 186–87. http://dx.doi.org/10.1017/s0424820100179683.

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Even the best present day ultrahigh resolution electron microscopes embody a paradox. They are equipped with the most modern ion pumps, cryopumps or turbomolecular pumps, but the forepumps are oil-sealed rotary pumps invented by Gaede in 1905. Consequently efficient protective systems are necessary to prevent oil-derived vapour from contaminating the specimen, the objective lens aperture diaphragm, the field emission or lanthanum boride electron sources and other sensitive areas. Continuously operable, reciprocating, dry fore-vacuum pumps, based on our designs, have been made and sold by Varian for over three years and have proved reliable in a wide range of equipment. Electron microscopes too, should be provided with oil-free forepumps.The need for oil-free forepumps occurred to one of us in 1949 when it was shown that pump oil was the major source of the carbonaceous contamination of microscope specimens and objective lens diaphragms. Materials available at that time seemed unsuitable for the construction of oil-free forepumps but during 1968 we learnt that highly wear resistant, low-friction composites of polytetrafluoroethylene (PTFE) filled with finely divided bronze, graphite, etc. were being marketed. In 1970 we began to devise a practical oil-free pump. Rotary designs were rejected because all practicable shaft seals require oil lubrication to transfer heat from the seal to the shaft to prevent the seal material from reaching temperatures at which it would soften and wear rapidly. Each lubricated shaft seal would expose, at least, a narrow annulus of oil to the vacuum in the working chamber and seal wear would lead to substantial leakage of oil.

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Ni Kadek Peniasih, I Gede Suranaya Pandit, and Dewa Gede Semara Edi. "Analysis of Microbial Contamination in Oreochromis Niloticus in Waduk Muara Nusa Dua." SEAS (Sustainable Environment Agricultural Science) 4, no. 1 (2020): 53–59. http://dx.doi.org/10.22225/seas.4.1.1688.53-59.

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This study aims to determine the microbiological contamination in the main water source of the Muara Nusa Dua Reservoir, the Tukad Badung River, and to determine the microbiological quality of fresh Oreochromis niloticus caught in the Muara Nusa Dua Reservoir in Denpasar. The study was conducted in May-August 2019 at the Denpasar Veterinary Laboratory. The method used is a descriptive method that aims to describe or describe the condition of the Tukad Badung watershed which empties into the Muara Nusa Dua Reservoir (Estuary Dam). Objective tests include the total bacterial test, the Coliform test, and the Escherichia coli contamination test. Water quality measurements are also carried out as supporting data from this study. The results of the study stated that there was microbiological contamination in the water source of the Muara Nusa Dua Reservoir, the Tukad Badung river, which also had an impact on the waters of the Muara Nusa Dua Reservoir. Microbiological contamination research results showed the microbiological quality of ten samples of Oreochromis niloticus in the form of the highest total bacteria was at 2.2x104, the highest total Coliform was 1.9x104 and the highest Escherichia coli contamination was at 93 APM / g with an average reservoir water quality Muara Nusa Dua in the form of temperature 27.3 °C, salinity 0.208 ‰, degree of acidity (pH) 6.5, dissolved oxygen (DO) 5,97 ppm. Organoleptic observations included the appearance, smell, and texture of Oreochromis niloticus with good results because when testing Oreochromis niloticus is still alive

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Leclair, Daniel, Jeffrey M. Farber, Franco Pagotto, Sandy Suppa, Bill Doidge, and John W. Austin. "Tracking sources ofClostridium botulinumtype E contamination in seal meat." International Journal of Circumpolar Health 76, no. 1 (2017): 1380994. http://dx.doi.org/10.1080/22423982.2017.1380994.

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Loughlin, Thomas R., Michael A. Castellini, and Gina Ylitalo. "Spatial aspects of organochlorine contamination in northern fur seal tissues." Marine Pollution Bulletin 44, no. 10 (2002): 1024–34. http://dx.doi.org/10.1016/s0025-326x(02)00149-2.

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Al-Ghasem, Adnan, G. L. Morrison, and John P. Platt. "Experimental and Numerical Investigation of a Gas Compressor Windback Seal." Journal of Tribology 129, no. 1 (2006): 129–34. http://dx.doi.org/10.1115/1.2401205.

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The effectiveness of a computational fluid dynamics (CFD) commercial code to accurately predict the leakage rate for a windback seal was evaluated. The windback seal under consideration has a rectangular cavity and is similar in design to a gas tooth on stator annular labyrinth seal. The main difference is the windback seal has only one tooth, which continuously winds around the shaft like a screw thread. These seals are used in gas compressors to isolate the gas face seal from bearing oil. A purge gas is passed through the seal into the bearing housing. The helical design allows the seal to clear itself of any oil contamination. The objective is to determine if CFD simulations can be used along with a few experimental tests to study windback seals of this design. Comparison of measurement and predictions for a simple rectangular cavity windback seal shows predictions and measurements comparing very well with maximum differences of 5% for leakage rate. The variation of leakage with shaft speed and pressure ratio across the seal is accurately predicted by the CFD simulations.

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Jacksch, Susanne, Huzefa Zohra, Mirko Weide, Sylvia Schnell, and Markus Egert. "Cultivation-Based Quantification and Identification of Bacteria at Two Hygienic Key Sides of Domestic Washing Machines." Microorganisms 9, no. 5 (2021): 905. http://dx.doi.org/10.3390/microorganisms9050905.

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Detergent drawer and door seal represent important sites for microbial life in domestic washing machines. Interestingly, quantitative data on the microbial contamination of these sites is scarce. Here, 10 domestic washing machines were swab-sampled for subsequent bacterial cultivation at four different sampling sites: detergent drawer and detergent drawer chamber, as well as the top and bottom part of the rubber door seal. The average bacterial load over all washing machines and sites was 2.1 ± 1.0 × 104 CFU cm−2 (average number of colony forming units ± standard error of the mean (SEM)). The top part of the door seal showed the lowest contamination (11.1 ± 9.2 × 101 CFU cm−2), probably due to less humidity. Out of 212 isolates, 178 (84%) were identified on the genus level, and 118 (56%) on the species level using matrix-assisted laser desorption/ionization (MALDI) Biotyping, resulting in 29 genera and 40 identified species across all machines. The predominant bacterial genera were Staphylococcus and Micrococcus, which were found at all sites. 22 out of 40 species were classified as opportunistic pathogens, emphasizing the need for regular cleaning of the investigated sites.

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Remenda, V. H., and G. Kamp. "Contamination from Sand-Bentonite Seal in Monitoring Wells Installed in Aquitards." Ground Water 35, no. 1 (1997): 39–46. http://dx.doi.org/10.1111/j.1745-6584.1997.tb00058.x.

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Kryshev, I. I., and T. G. Sazykina. "Radiological consequences of radioactive contamination of the Kara and Barents Seas." Journal of Environmental Radioactivity 29, no. 3 (1995): 213–23. http://dx.doi.org/10.1016/0265-931x(95)00034-8.

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Kryshev, I. I., and T. G. Sazykina. "Radiological consequences of radioactive contamination of the Kara and Barents Seas." Fuel and Energy Abstracts 37, no. 3 (1996): 228. http://dx.doi.org/10.1016/0140-6701(96)89213-7.

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Ilyin, G. V., I. S. Usyagina, N. E. Kasatkina, and D. A. Valuyskaya. "RADIOECOLOGICAL STATUS OF ARCTIC MARINE ECOSYSTEMS AND CURRENT OCEAN AND COASTAL MANAGEMENT." Transaction of the Kola Science Centre 11, no. 4 (2020): 261–75. http://dx.doi.org/10.37614/2307-5252.2020.11.4.013.

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We examined the radioecological status of seawater from arctic seas currently used for coastal and offshore innovative industrial and socio-economic projects. We analyzed processes that affect the formation of the current radioecological background. We showed that the volumetric activity of man-made radionuclides in seawater has been steadily low over the past decade. We believe that this is caused by the general influence of global sources of radioactive contamination. Among them, atmospheric deposition and transoceanic transport are most significant. We determined a substantial difference between the concentration of 137Cs in seawater of the Barents and Kara seas and that in the Laptev and East Siberian seas. This difference is determined by the significant influence of polluted Atlantic water on the Barents and Kara seas and its far weaker impact on the Laptev and East Siberian seas. We found out regional and local patterns of the distribution of radionuclides in the environment of arctic seas, which are the most important for the study and development of the logistics network in the Russian Arctic in the light of the prospective development of the transport and resources of those seas.

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Pinto, Aline Bartelochi, and Ana Julia Fernandes Cardoso Oliveira. "Diversidade de microrganismos indicadores utilizados na avaliação da contaminação fecal de areias de praias recreacionais marinhas: estado atual do conhecimento e perspectivas." O Mundo da Saúde 35, no. 1 (2011): 105–14. http://dx.doi.org/10.15343/0104-7809.2011351105114.

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DellaX’ma Nandari, Anak Agung Made Semariyani, and Ni Made Ayu Suardani Singapurwa. "Chemical and Microbiology Analysis of Salted Anchovies (Stolephorus sp.) in East Denpasar Traditional Market." SEAS (Sustainable Environment Agricultural Science) 4, no. 2 (2020): 120–29. http://dx.doi.org/10.22225/seas.4.2.2621.120-129.

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 Jengki anchovies are one of the raw food ingredients that are preserved using salt. Basically, salting is done to reduce the water content in the fish so that bacteria cannot live and develop. This study aims to determine the chemical and microbiological contamination of salted anchovies in East Denpasar Traditional Market. This research is a descriptive study using survey and experimental methods in the laboratory. Based on data from the Department of Industry and Trade in Denpasar, there are 7 traditional markets in East Denpasar. The number of samples studied was 43 samples from 75 existing populations. The parameters of this research were formaldehyde, moisture content, TPC, E. coli and organoleptics. The results showed that none of the 43 samples contained formalin. The results of the water content test were obtained that all samples met the SNI 8273: 2016 requirements. From the results of the TPC test, 35 samples met the requirements and 8 samples exceeded the limits set by SNI 8273: 2016, namely the maximum limit of TPC contamination, namely 1.0 × 105 colonies / gram. The E. coli test results from 43 samples met the SNI 8273: 2016 requirements, namely the maximum limit of E. coli contamination ˂3.6 APM / gram. From the results of the organoleptic test on appearance, smell, taste, texture, fungus and overall acceptance, all assessments were significantly different, with the characteristics of a dull to clean bright appearance, specific to type, specific odor but less strong, salty taste and less specific type, dry solid texture to dense less dry.

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Costa, Gardel Nepomuceno, Elizabeth Ferreira Martinez, Aluísio Martins de Oliveira Ruellas, Daiane Cristina Peruzzo, Júlio Cesar Joly, and Marcelo Henrique Napimoga. "Microbiological Sealing Analysis of a Tapered Connection and External Hexagon System." International Journal of Dentistry 2017 (2017): 1–4. http://dx.doi.org/10.1155/2017/3849085.

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Considering the variety of implant connection systems available in the market and the contrasting literature regarding tapered connection systems in terms of bacterial leakage, the aim of this in vitro study was to compare the effectiveness of the bacterial seal at the implant/abutment interface between an external hexagon and a tapered connection system. Twelve sets of indexed tapered connection components and twelve sets of external hexagon connection components were used for microbiological analysis. In addition, for each model, an implant with its respective prosthetic abutment was used as a negative control and another as a positive control of microbial contamination. Failure of the abutment/implant interface seal was observed via turbidity or presence of deposits in the culture. Descriptive analysis of the data and relative frequency (percentage) as well as Fisher’s exact test were used at a significance level of 5%. Two of ten (20%) external hexagon specimens showed contamination against 0/10 (0%) tapered connection implants. In conclusion, both implant/abutment connections were able to prevent bacterial leakage in vitro.

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D’huys, Karlien, Wouter Saeys, and Bart De Ketelaere. "Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging." Journal of Imaging 2, no. 4 (2016): 33. http://dx.doi.org/10.3390/jimaging2040033.

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Ridgway, J., and G. Shimmield. "Estuaries as Repositories of Historical Contamination and their Impact on Shelf Seas." Estuarine, Coastal and Shelf Science 55, no. 6 (2002): 903–28. http://dx.doi.org/10.1006/ecss.2002.1035.

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Al-Temeemi, Abdul-Salam, Jamal Al-Hubail, and Ahmad Al-Khayat. "Assessing Occupational Exposure to Surface Contaminants in Kuwaiti Educational Buildings." Frontiers Research of Architecture and Engineering 2, no. 3 (2019): 1. http://dx.doi.org/10.30564/frae.v2i3.843.

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The prevalence of surface contaminants, such as potentially harmful bacteria, within building environments in the State of Kuwait is not known.To the authors’ knowledge, this article is the frst of such a report. A total of 342 stool samples were collected from 46 secondary schools to evaluate indoor occurrences of E. coli bacteria within selected lavatory surfaces. After microbiological testing, the results for the spread of the E. coli bacteria were categorized by total count, sampling location dependency, contamination level comparison between genders, and lavatory fxtures (i.e. seat and squat toilets). The results revealed that 7 schools have a bacterial contamination problem, there is cross-contamination between surfaces in the lavatory stalls, the boys’ lavatories were less sanitary than the girls’, and that the squat-style toilets are more contaminated than the seat-style. The results suggest that there is signifcant risk of spread of bacterial infection among students via contaminated hands and surfaces in the lavatory area in some schools. Thus, this study emphasizes the need to improve environmental hygiene and enhanced sanitation in these schools. In addition, conclusions can be drawn as to the effectiveness of the janitorial staff employed by the schools and the effcacy of the cleaning regime used in the lavatories. Furthermore, based on the fndings, there are architectural design consequences as squat-style toilets might be excluded in lavatories designed for schools to be constructed in the future.

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Tatsukawa, R. "Contamination of Chlorinated Organic Substances in the Ocean Ecosystem." Water Science and Technology 25, no. 11 (1992): 1–8. http://dx.doi.org/10.2166/wst.1992.0266.

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Persistent organochlorines such as PCBs, DDTs and HCHs are ubiquitous contaminants found in seas and oceans worldwide. They are transferred from terrestrial contaminant sources to open ocean through atmosphere and ultimately deposit into the oceanic waters. The tropical regions are likely to contribute greatly to the global contamination of some organochlorines in recent years. The contaminants in water phase are taken into ecosystems following the prey-predator relationship in the food-chain. In this context, cetaceans like dolphins, porpoises and whales are recognized as one of the animal groups most at risk from persistent organochlorines in the environment. They accumulate extremely high concentrations of organochlorines through feeding, and transfer large quantities to offspring during lactation. Unfortunately, they have a small capacity to degrade these contaminants. It may be concluded that marine mammals, particularly cetaceans, are among the most vulnerable organisms to long-term toxicity of hazardous man-made chenicals.

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Cadnum, Jennifer, Scott Livingston, Thriveen Sankar Chittoor Mana, Annette Jencson, Sarah Redmond, and Curtis Donskey. "1218. Evaluation of a Novel Sporicidal Spray Disinfectant for Decontamination of Surfaces in Healthcare." Open Forum Infectious Diseases 6, Supplement_2 (2019): S438. http://dx.doi.org/10.1093/ofid/ofz360.1081.

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Abstract Background Surfaces in healthcare facilities are typically cleaned by manual application of liquid disinfectants. However, thoroughness of cleaning is often suboptimal and application can be challenging and time-consuming when surfaces are irregular. Methods We tested the effectiveness of a novel spray disinfectant technology that uses an electrostatic sprayer to thoroughly apply a sporicidal disinfectant to surfaces after minimal pre-cleaning to remove visible soil. In a laboratory setting, we compared the effectiveness of the spray disinfectant vs. manual application of disinfectant for removal of Clostridium difficile spores inoculated onto the seat, armrest, and seat back of a wheelchair and measured the time required for each method of disinfection. In a healthcare setting, we tested the effectiveness of a 15-second spray application for reduction of C. difficile spores on 130 items with irregular or hard to clean surfaces, including 30 wheelchairs, 40 pieces of portable equipment, and 30 waiting room chair seats. Results In laboratory testing, application of disinfectant using the electrostatic sprayer was as effective as wiping in reducing C. difficile spores inoculated onto wheelchair surfaces, but required only one-fourth the time for application. C. difficile spore contamination was common on mobile equipment, wheelchairs, and waiting rooms chairs, and spray application of the sporicidal disinfectant was effective in reducing contamination (figure). Conclusion Commonly shared items such as wheelchairs, portable equipment, and waiting room chairs were frequently contaminated with C. difficile spores. Application of a sporicidal disinfectant using an electrostatic sprayer provided a rapid and effective means to reduce spore contamination on these surfaces. Disclosures All authors: No reported disclosures.

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Zhang, Bin, Haocen Hong, Min Yu, and Huayong Yang. "Leakage analysis and ground tests of knife edge indium seal to lunar sample return devices." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 6 (2018): 2010–22. http://dx.doi.org/10.1177/0954410018768425.

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This work deals with the lunar sample return project, which requires lunar samples to be returned back to the ground without contamination. In this paper, a knife edge indium seal is proposed as a primary sealing form, where indium–silver alloy is welded into an annular groove of a cylindrical container firstly and then extruded by an annular knife edge of a cylindrical lid. The analysis of the leakage and sealing reliability of knife edge indium seal is the main aim of this paper. Firstly, the pretreatment of knife edge indium seal is discussed. Key techniques on indium welding are studied to evaluate its sealing reliability, with the tensile strength and welding void ratio mainly being discussed. Secondly, by means of “Roth” leakage theory, mathematical models on the leak rate for knife edge seal are established. By means of the finite element analysis, the knife edge geometry is optimized with minimum pressing force required. The results justify that the knife edge seal demands much lower pressing force to achieve a considerable sealing performance, which is suitable for low-powered operation. Finally, the ground tests are carried out to evaluate the feasibility of the indium welding and to measure the leak rate of the knife edge indium seal. Experimental results demonstrate the indium welding onto the stainless steel container is feasible, and the leak rate at room temperature is 3.0 × 10−10 Pa·m3/s, which is much lower than the rubber O-type ring seal. The knife edge indium seal is suitable for lunar sample return devices.

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Focardi, S., R. Bargagli, and S. Corsolini. "Isomer-specific analysis and toxic potential evaluation of polychlorinated biphenyls in Antarctic fish, seabirds and Weddell seals from Terra Nova Bay (Ross Sea)." Antarctic Science 7, no. 1 (1995): 31–35. http://dx.doi.org/10.1017/s095410209500006x.

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To provide data on the degree of contamination of the marine ecosystem isomer-specific concentrations of polychlorinated biphenyls, including planar, mono- and di-ortho congeners, were measured in the Weddell seal, the Adélie penguin, the south polar skua, and in two species of Antarctic fish (Trematomus bernacchii and Chionodraco hamatus) from Terra Nova Bay, Antarctica. The results show a clear relation between PCB concentrations and trophic level, in the order fish < Adélie penguin < Weddell seal. The higher values found in the skua appear to be related to its migration to more contaminated lower latitudes. The data for the various PCB congeners were used to calculate toxic potential in the different animals. The 2,3,7,8-TCDD toxic equivalents of coplanar congeners were estimated by the “toxic equivalent factors” (TEFs) approach. The highest values of TEFs were found in the south polar skua and Weddell seal. Values in the other species were considerably lower.

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Abdulmunem, Oday M., Ali Mazin Abdul-Munaim, Mario Mendez Aller, Sascha Preu, and Dennis G. Watson. "THz-TDS for Detecting Glycol Contamination in Engine Oil." Applied Sciences 10, no. 11 (2020): 3738. http://dx.doi.org/10.3390/app10113738.

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There continues to be a need for an in-situ sensor system to monitor the engine oil of internal combustion engines. Engine oil needs to be monitored for contaminants and depletion of additives. While various sensor systems have been designed and evaluated, there is still a need to develop and evaluate new sensing technologies. This study evaluated Terahertz time-domain spectroscopy (THz-TDS) for the identification and estimation of the glycol contamination of automotive engine oil. Glycol contamination is a result of a gasket or seal leak allowing coolant to enter an engine and mix with the engine oil. An engine oil intended for use in both diesel and gasoline engines was obtained. Fresh engine oil samples were contaminated with four levels of glycol (0 ppm, 150 ppm, 300 ppm, and 500 ppm). The samples were analyzed with THz-TDS and converted to frequency domain parameters of refractive index and absorption coefficient. While both parameters showed potential, the absorption coefficient had the best potential and was able to statistically discriminate among the four contamination levels.

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Gursky, Yu N. "Reveal appraisement level of anthropogenic pollution on the basis of geochemistry studying the interstitial waters of marine and freshwater sediments." Moscow University Bulletin. Series 4. Geology, no. 5 (October 28, 2017): 49–58. http://dx.doi.org/10.33623/0579-9406-2017-5-49-58.

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The chemical composition of interstitial waters from several of inland seas and NPWS, exposed to anthropogenic pollution. The regularities of distribution of pollution in the Dnieper-Bug estuary and Gelendzhik Bay of the Black sea in the Eastern Harbor of Alexandria Mediterranean Sea. Most of the contamination confines to the upper layers of sediments and near mouth zones. A significant role is played by secondary contamination related to the dissolution and accumulation of metals and nutrients in the interstitial water and their migration in the water column. When factor analysis for the aggregate impact of potentially mobile forms of metals in the Diepr-Bug estuary factor of anthropogenic pollution came in first place. Studies pollution in the Pjasino Lake near town Norilsk.

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Bamps, Bram, Karlien D'huys, Ina Schreib, Benjamin Stephan, Bart De Ketelaere, and Roos Peeters. "Evaluation and optimization of seal behaviour through solid contamination of heat‐sealed films." Packaging Technology and Science 32, no. 7 (2019): 335–44. http://dx.doi.org/10.1002/pts.2442.

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Cossaboon, Jennifer M., Priya M. Ganguli, and A. Russell Flegal. "Mercury offloaded in Northern elephant seal hair affects coastal seawater surrounding rookery." Proceedings of the National Academy of Sciences 112, no. 39 (2015): 12058–62. http://dx.doi.org/10.1073/pnas.1506520112.

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Methylmercury (MeHg) is a potent neurotoxin that is biomagnified approximately 1–10 million-fold in aquatic carnivores such as the Northern elephant seal (Mirounga angustirostris), whose excreta and molted pelage, in turn, constitute a source of environmental MeHg contamination at the base of marine food chains. The potential for this top-down contamination is greatest in coastal areas with productive marine ecosystems that provide ideal habitats for large marine mammal colonies that can number in the thousands. This recycling of MeHg was evidenced by comparing total mercury (HgT) and MeHg concentrations in seawater, and HgT in molted pelage of M. angustirostris, at the Año Nuevo State Reserve pinniped rookery with concentrations at neighboring coastal sites in Central California. Seawater MeHg concentrations around the rookery (average = 2.5 pM) were markedly higher than those at the comparison coastal sites (average = 0.30 pM), and were as high as 9.5 pM during the M. angustirostris molting season. As a consequence, excreta and molts from this marine mammal colony, and presumably other marine predator populations, constitute a major source of MeHg at the base of the local marine food chain.

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Michaux, Johan, Markus Dyck, Peter Boag, Stephen Lougheed, and Peter Van Coeverden de Groot. "New Insights on Polar Bear (Ursus maritimus) Diet from Faeces based on Next-Generation Sequencing Technologies." ARCTIC 74, no. 1 (2021): 87–99. http://dx.doi.org/10.14430/arctic72239.

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Practical tools to quantify range-wide dietary choices of the polar bear have not been well developed, thus impeding the monitoring of this species in a changing climate. Here we describe our steps toward non-invasive polar bear diet determination with the optimization of 454 pyrosequencing of a 136 base pair (bp) mitochondrial cytochrome b (cytb) fragment amplified from the extracts of captive and wild polar bear faeces. We first determine the efficacy, reliability, and accuracy of our method using five faecal samples from a captive polar bear fed a known diet at the Canadian Polar Bear Habitat in Cochrane, Ontario, Canada; 19 samples from three polar bears at the Metro Toronto Zoo, Toronto, Ontario, Canada; and seven samples from seven wild (unfed) polar bears from a holding facility in Churchill, Manitoba, Canada. We report 91% overall success in amplifying a 136 bp cytb amplicon from the faeces of polar bears. Our DNA analyses accurately recovered the vertebrate diet profiles of captive bears fed known diets. We then characterized multiyear vertebrate prey diet choices from free-ranging polar bears from the sea ice of the M’Clintock Channel polar bear management unit, Nunavut, Canada (n = 117 from an unknown number of bears). These data point to a diet unsurprisingly dominated by ringed seal (Pusa hispida) while including evidence of bearded seal (Erignathus barbatus), harbour seal (Phoca vitulina), muskox (Ovibos moschatus ssp.), Arctic fox (Vulpes lagopus), wolf (Canis lupus), Herring Gull (Larus argentatus), and Willow Ptarmigan (Lagopus lagopus). We found low levels of contamination (< 3% of sequences when present) and suggest specific process improvements to reduce contamination in range-wide studies. Together, these findings indicate that next-generation sequencing-based diet assessments show great promise in monitoring free-ranging polar bears in this time of climate change. 

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Tsydenova, Oyuna, Tu Binh Minh, Natsuko Kajiwara, Valeriy Batoev, and Shinsuke Tanabe. "Recent contamination by persistent organochlorines in Baikal seal (Phoca sibirica) from Lake Baikal, Russia." Marine Pollution Bulletin 48, no. 7-8 (2004): 749–58. http://dx.doi.org/10.1016/j.marpolbul.2003.10.027.

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Evans, S. M., and G. J. Nicholson. "The use of imposex to assess tributyltin contamination in coastal waters and open seas." Science of The Total Environment 258, no. 1-2 (2000): 73–80. http://dx.doi.org/10.1016/s0048-9697(00)00507-6.

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Sonia, Ashok Kumar, and Keereyadath Priya Dasan. "Feasibility studies of cellulose microfiber (CMF) reinforced poly(ethylene-co-vinyl acetate) (EVA) composites for food packaging applications." Science and Engineering of Composite Materials 23, no. 5 (2016): 489–94. http://dx.doi.org/10.1515/secm-2014-0252.

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AbstractRecently, there has been increased interest in the extraction of cellulose microfiber (CMF)/nanofibers from plant sources and their utilization as fillers in polymers. These natural fibers are characterized by good mechanical, thermal, and biodegradability properties. The present work was aimed at studying the feasibility of these fiber-reinforced polymer in food packaging. Poly(ethylene-co-vinyl acetate) (EVA) is a common food packaging material used in refrigerated items. The CMF/EVA composite films were exposed to milk, curd, and orange juice at fixed time intervals at three different temperatures and the microbial growth profile in the food material was evaluated. The incorporation of CMF in EVA was found to have no impact on the microbial contamination or proliferation of microbial growth in the food materials.

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Miroshnichenko, O. N., and A. A. Paraskiv. "137Cs concentration in surface waters of Far Eastern seas: Results of expeditionary research in 2018." Marine Biological Journal 5, no. 3 (2020): 55–63. http://dx.doi.org/10.21072/mbj.2020.05.3.05.

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Based on the results of expeditionary research carried out during the 82nd cruise of the RV “Akademik M. A. Lavrentyev” (01.06.2018–20.07.2018), the assessment of current levels of concentration activity of technogenic radionuclide 137Cs in surface waters of Far Eastern seas is given. The studies were carried out in the northwestern part of the Sea of Japan, the southern part of the Sea of Okhotsk, the coastal waters of the Pacific Ocean near the Kamchatka Peninsula, and the western part of the Bering Sea. Activity of 137Cs in seawater samples was determined by sorption method using two series-connected adsorbers with subsequent measurement of 137Cs content via its gamma-emitting daughter radionuclide 137mBa. Sorption efficiency was assessed by the difference in activity on the first and second adsorbers. A comparative analysis of contamination levels of water areas studied was made. It was revealed that 137Cs volumetric activity in surface water of the Sea of Japan varied from (2.9 ± 0.1) to (5.1 ± 0.3) Bq·m−3, in the Sea of Okhotsk – from (1.8 ± 0.1) to (2.3 ± 0.1) Bq·m−3, and in the Bering Sea – from (1.7 ± 0.1) to (3.1 ± 0.1) Bq·m−3. The maximum 137Cs concentrations were registered in the Sea of Japan, which might be due to its isolation from other water areas and presence of secondary sources of radionuclide intake. In general, contamination of adjacent water areas is insignificant, and fluctuations in concentrations occur within technogenic isotopes global background in the marginal seas of the Pacific Ocean.

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Osborne, Thomas H., Seamus A. Ward, Kazi M. Ahmed, and Joanne M. Santini. "Reservoirs of faecal indicator bacteria in well-head hand pumps in Bangladesh." Journal of Water and Health 16, no. 3 (2018): 487–90. http://dx.doi.org/10.2166/wh.2018.042.

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Abstract The majority of the population of Bangladesh (90%) rely on untreated groundwater for drinking and domestic use. At the point of collection, 40% of these supplies are contaminated with faecal indicator bacteria (FIB). Recent studies have disproved the theory that latrines discharging to shallow aquifers are the major contributor to this contamination. In this study, we tested the hypothesis that hand pumps are a reservoir of FIB. We sampled the handle, spout, piston and seal from 19 wells in Araihazar Upazila, Bangladesh and identified that the spout and seal were reservoirs of FIB. These findings led to our recommendation that well spouts be regularly cleaned, including the removal of precipitated deposits, and that the seals be regularly changed. It is envisaged that one or both of these interventions will reduce the numbers of FIB in drinking water, thereby reducing the burden of diarrhoeal disease in Bangladesh.

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Alves, Deceles Cristina Costa, Paulo Sérgio Perri de Carvalho, and Elizabeth Ferreira Martinez. "In Vitro Microbiological Analysis of Bacterial Seal at the Implant-Abutment Interface Using Two Morse Taper Implant Models." Brazilian Dental Journal 25, no. 1 (2014): 48–53. http://dx.doi.org/10.1590/0103-6440201302178.

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The objective of this study was to evaluate the bacterial seal at the implant-abutment interface using two morse taper implant models, by means of an in vitro microbiological analysis. For that were used 15 implants with mini-abutments tightened by friction, no screws (Group 1); and 30 implants with screw-tightened abutments, of which 15 received 20 N.cm of closing torque (Group 2) and the other 15 received 30 N.cm (Group 3). Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. Friction implants (Group 1) were activated by tapping and a torque wrench was used for screw-tightened implants (Groups 2 and 3). Each abutment/implant set was immersed in test tubes containing 5 mL of brain-heart infusion broth and incubated at 37 °C for 14 days, observed daily for the presence of contamination. A statistically significant difference was observed regarding the number of contaminated implants. There was greater contamination in Group 2 implants (p<0.05), with no statistically significant difference between the other groups (Group 1 = 20% and Group 3 = 0%). It was concluded that there was no significant difference in in vitro bacterial sealing between implants with mini-abutments tightened by friction without screws and implants with screw-tightened abutments with 30 N.cm of closing torque. The difference in closing torque altered the in vitro sealing ability of the tested abutments, with a greater contamination for components that received a closing torque of 20 N.cm.

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Kim, Deok-Hoon, Young-Sang Cho, and Peter Elenius. "Flip Chip for Image Sensor Packaging." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, DPC (2011): 001898–917. http://dx.doi.org/10.4071/2011dpc-wp36.

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The use of flip chip interconnects for image sensor packaging provides several unique challenges during packaging as well as benefits to the customer. The principal challenges during assembly include the requirements of: no contamination of the image sensor during reflow, fabrication of a sealing structure to prevent future environmental contamination of the image sensor, and fabrication of a solder joint structure for the seal ring that can pass pre-conditioning. To achieve these requirements, the use of a fluxless solder reflow process and transient liquid phase (TLP) bonding will be explained. Benefits to the customer for this type of flip chip image sensor packaging as compared to chip on board (COB) and thru silicon via (TSV) packages is a thinner camera module and versus TSV packages the ability to pass all required reliability tests without the use of an underfill. Reliability test results will be shown for thermal cycling, drop, and bending tests.

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Maki, Hideaki, and Gen Kanaya. "Sediment Contamination with Hydrocarbons in Sanriku Coastal Seas after the 2011 Great East Japan Earthquake." Journal of The Japan Institute of Marine Engineering 51, no. 6 (2016): 820–27. http://dx.doi.org/10.5988/jime.51.820.

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El-Oun, Z. B., P. H. Neller, and A. B. Turner. "Sealing of a Shrouded Rotor–Stator System With Preswirl Coolant." Journal of Turbomachinery 110, no. 2 (1988): 218–25. http://dx.doi.org/10.1115/1.3262184.

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This paper describes an experimental study of a modeled gas turbine rotor–stator system using both preswirled blade coolant and radially outward flowing disk coolant. A double mitered rim seal was used together with, for some tests, an inner seal below the preswirl nozzles and blade feed holes in the rotor which were situated at the same radius. Some flow visualization results are presented together with measurements of pressure distribution, internal flow distribution, and the minimum seal flow necessary to prevent “mainstream” gas ingress into the wheelspace. The experiments are described for a range of rotational speeds up to Reθ = 1.8×106 for various combinations of preswirl flow, disk coolant flow, and “blade” coolant flow. The preswirled coolant flow is shown to have little effect on the pressure distribution below the preswirl nozzles but a gas concentration sampling technique showed that considerable contamination of the preswirled coolant by the frictionally heated disk coolant can occur. A clear pressure inversion effect was observed when coolant was provided by the preswirl nozzles only, whereby the pressure under the rim seal increased with increasing rotational speed. Except for the lowest flow rates, blade coolant flow is shown to increase the sealing flow requirement, but to a very much reduced extent when disk coolant flow is used simultaneously. A nonlinear relationship between minimum sealing flow and Reθ is produced when the blade cooling system is in operation.

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Treijs, Juris, Edmunds Teirumnieks, and Viktors Mironovs. "Environment Pollution With Oil Products and Review of Possibilities for Collection Thereof." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 1 (August 5, 2015): 301. http://dx.doi.org/10.17770/etr2011vol1.926.

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The largest global pollution nowadays gives oil and oil products. This contamination poses a danger to the environment and aquatic eco-systems. Not only seas but also small water bodies and watercourses, as well as coastal areas, soil and groundwater are contaminated with oil products. Contamination results in destruction of some plants or animals, but in events of high oil contamination also of the entire ecosystem. Latvia has inherited the oil pollution from both the Soviet Union large-scale industry and its military facilities, as well as at present the oil products are getting into environment from petrol stations, accidents, and from the cross-border pollution. In many cases of oil spills, people are trying to collect them in order to have no impact on the environment, but unfortunately very often, even in most cases this does not occur. Financial resources, as well as the lack of appropriate technologies or restricted possibilities for their application are the limiting factors. The article deals with the traditional methods of oil collection in water and also describes options for decontamination of polluted soil from the oil products. A brief insight is provided into application of ferromagnetic sorbents, which is a new method for collection of oil and oil products.

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Peruzetto, Wheslley M., Elizabeth F. Martinez, Daiane C. Peruzzo, Júlio Cesar Joly, and Marcelo H. Napimoga. "Microbiological Seal of Two Types of Tapered Implant Connections." Brazilian Dental Journal 27, no. 3 (2016): 273–77. http://dx.doi.org/10.1590/0103-6440201600604.

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Abstract Tapered implant connections have gained wide popularity for being more resistant to fatigue and for promoting a better seal against bacterial infiltration than conventional connections. The aim of this study was to evaluate the bacterial seal at the implant-abutment interface using two Morse taper implant models, by in vitro microbiological analysis. Eleven non-indexed and 11 indexed abutments were selected and connected to their respective implants with a 20 N torque, according to manufacturer's recommendation. Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. For control, one non-contaminated abutment-implant set from each group (negative control) and one contaminated implant with no abutment (positive control) were used. The specimens were immersed in BHI broth and maintained in an incubator at 37 °C for 14 days to assess the development of bacterial contamination. The results revealed that 36.4% (n=4) of the indexed components and 90.9% (n=10) of the non-indexed components allowed bacterial leakage, with significant difference between groups (p=0.0237). In conclusion, both tapered components failed to provide adequate sealing to bacterial leakage, although the indexed type components showed a superior seal compared with non-indexed components.

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Sherwood, Owen A., Jessica D. Rogers, Greg Lackey, Troy L. Burke, Stephen G. Osborn, and Joseph N. Ryan. "Groundwater methane in relation to oil and gas development and shallow coal seams in the Denver-Julesburg Basin of Colorado." Proceedings of the National Academy of Sciences 113, no. 30 (2016): 8391–96. http://dx.doi.org/10.1073/pnas.1523267113.

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Unconventional oil and gas development has generated intense public concerns about potential impacts to groundwater quality. Specific pathways of contamination have been identified; however, overall rates of contamination remain ambiguous. We used an archive of geochemical data collected from 1988 to 2014 to determine the sources and occurrence of groundwater methane in the Denver-Julesburg Basin of northeastern Colorado. This 60,000-km2 region has a 60-y-long history of hydraulic fracturing, with horizontal drilling and high-volume hydraulic fracturing beginning in 2010. Of 924 sampled water wells in the basin, dissolved methane was detected in 593 wells at depths of 20–190 m. Based on carbon and hydrogen stable isotopes and gas molecular ratios, most of this methane was microbially generated, likely within shallow coal seams. A total of 42 water wells contained thermogenic stray gas originating from underlying oil and gas producing formations. Inadequate surface casing and leaks in production casing and wellhead seals in older, vertical oil and gas wells were identified as stray gas migration pathways. The rate of oil and gas wellbore failure was estimated as 0.06% of the 54,000 oil and gas wells in the basin (lower estimate) to 0.15% of the 20,700 wells in the area where stray gas contamination occurred (upper estimate) and has remained steady at about two cases per year since 2001. These results show that wellbore barrier failure, not high-volume hydraulic fracturing in horizontal wells, is the main cause of thermogenic stray gas migration in this oil- and gas-producing basin.

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Achmad, Ali. "IMPORTANCE OF THIN SEAMS RECONCILIATION IN A NEW COAL MINING PROSPECT AREA." Indonesian Mining Professionals Journal 2, no. 2 (2021): 85–94. http://dx.doi.org/10.36986/impj.v2i2.37.

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Coal thin seams in the coal mining industry are often considered by company as waste material or it is not gives a significance revenue. Actual condition it is true but this seams actually can be mined potentially and giving some additional profit if we do the plan and managed it correctly. In this paper will discuss and explaining about how much the importance related to optimalization of coal thin recovery in coal mining industry in the technical and economical perspectives. Starting on the iso-thickness polygon in the pit shell design that have been agreed (sign off) to coal reserves reconciliation that had mined completely. The Geologist must undertakes monthly monitoring about the sum of coal thin seams and it is variance between actual versus model. If they find loses indication, they must to do investigation immediately. The writer take a study case from one of area’s PT Arutmin Indonesia consession. The located of research area is situated in “Pit 4 Spessartine” with the coal thin seams succession from interval delta lower 2 – echo 1 lower. The Stratigraphy of research area is a part of Warukin Formation – Asem Asem Sub Basin. If we look in the engineering, mine scheduling, operational sequence and also marketing linkage perspectives, actually these thin seams gives a much economical profit but on the other hand it can gives a loss material such as coal contamination and increasing of ash content. In this paper the writer also reviewing the geological perspective so it can be known about the general parameters which controlled about coal sedimentary deposited among of them. We will disclose the paleo-peats distribution, paleo-base of their wet land or marsh and the last one is knowing about the water currents within the coal depositional environment.

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Andrés, Luis San, and Adolfo Delgado. "Identification of Force Coefficients in a Squeeze Film Damper With a Mechanical End Seal—Part I: Unidirectional Load Tests." Journal of Engineering for Gas Turbines and Power 129, no. 3 (2006): 858–64. http://dx.doi.org/10.1115/1.2436571.

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Abstract:

Squeeze film dampers (SFDs) with low levels of external pressurization and poor end sealing are prone to air entrapment, thus not generating enough damping capability. Single frequency, unidirectional load tests were conducted on a SFD test rig replicating a commercial jet-engine configuration. The damper journal is 2.54cm in length and 12.7cm in diameter, with nominal clearance of 0.127mm. The SFD feed end is flooded with oil, while the discharge end contains a recirculation groove and four orifice ports, and a mechanical seal ring in contact with the damper journal. A wave spring pushes the ring ensuring tight sealing to prevent gas ingestion. The mechanical seal also serves to contain the lubricant within the squeeze film land for extended periods of time and; while in operation, to prevent contamination of the ball bearing cartridge. The measurements conducted without and with lubricant in the squeeze film lands, along with a frequency domain identification procedure, render the mechanical seal dry-friction force and viscous damping force coefficients as functions of frequency and motion amplitude. The end seal arrangement is quite effective in eliminating side leakage and preventing air entrainment into the film lands. Importantly enough, the dry friction force, arising from the contact forces in relative motion, increases significantly the test element equivalent viscous damping coefficients. The identified system damping coefficients are thus frequency and motion amplitude dependent, albeit decreasing rapidly as the motion parameters increase. Identified squeeze film force coefficients, damping and added mass, agree well with predictions based on the full film, short length damper model.

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Journal articles on the topic 'Seam contamination'

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