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Prasad, Deovrat, Prateek Sharma, Arif Babul, Gerard M. Voit i Brian W. O’Shea. "Cool-core cycles and Phoenix". Monthly Notices of the Royal Astronomical Society 495, nr 1 (6.05.2020): 594–99. http://dx.doi.org/10.1093/mnras/staa1247.
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ABSTRACT Recent observations show that the star formation rate (SFR) in the Phoenix cluster’s central galaxy is ∼500 M⊙ yr−1. Even though Phoenix is a massive cluster (M200 ≈ 2.0 × 1015 M⊙; z ≈ 0.6) such a high central SFR is not expected in a scenario in which feedback from an active galactic nucleus (AGN) maintains the intracluster medium in a state of rough thermal balance. It has been argued that either AGN feedback saturates in very massive clusters or the central supermassive black hole is too small to produce enough kinetic feedback and hence is unable to quench the catastrophic cooling. In this work, we present an alternate scenario wherein intense short-lived cooling and star formation phases followed by strong AGN outbursts are part of the AGN feedback loop. Using results from a 3D hydrodynamic simulation of a standard cool-core cluster (M200 ∼ 7 × 1014 M⊙; z = 0), scaled to account for differences in mass and redshift, we argue that Phoenix is at the end of a cooling phase in which an AGN outburst has begun but has not yet arrested core cooling. This state of high cooling rate and star formation is expected to last for ≲100 Myr in Phoenix.
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Prasad, Deovrat, Prateek Sharma i Arif Babul. "COOL CORE CYCLES: COLD GAS AND AGN JET FEEDBACK IN CLUSTER CORES". Astrophysical Journal 811, nr 2 (28.09.2015): 108. http://dx.doi.org/10.1088/0004-637x/811/2/108.
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Ferland, Marie A., Peter S. Roy i Colin V. Murray-Wallace. "Glacial Lowstand Deposits on the Outer Continental Shelf of Southeastern Australia". Quaternary Research 44, nr 2 (wrzesień 1995): 294–99. http://dx.doi.org/10.1006/qres.1995.1074.
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AbstractVibracores collected from water depths of 130 to 150 m on the outer continental shelf of southeastern Australia contain evidence for several cycles of shallow marine deposition. One of these vibracores (112/VC/134; lat. 33°24′S, long, 151°58′ E) preserves evidence for the last three glacial lowstands, as inferred from radiocarbon dating, amino acid racemization, and fossil mollusc assemblages. The core contains the inner-shelf molluscs Pecten fumatus, Placamen placidium, and Tawera gallinula, which today live in water depths of 10 to 50 m, in the cool waters of southern Australia. Radiocarbon dating and amino acid racemization analyses on multiple valves of P. fumatus in the core indicate three distinct age groupings of fossil molluscs: (1) those younger than 20,000 yr B.P., (2) those with minimum ages of about 100,000 yr, and (3) those with minimum ages of about 200,000 yr. We assign these sediments to oxygen isotope stages 2, 6, and 8, respectively. The core contains the first shallow-marine lowstand deposits to be recovered from the shelf of eastern Australia. These deposits constrain the last three glacial lowstands on this margin to water depths <130 m below present sea level.
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Schellenberger, Gerrit, Ewan O’Sullivan, Simona Giacintucci, Jan Vrtilek, Laurence P. David, Francoise Combes, Laura Bîrzan, Hsi-An Pan i Lihwai Lin. "Feedback in the Extremely Violent Group Merger NGC 6338". Astrophysical Journal 948, nr 2 (1.05.2023): 101. http://dx.doi.org/10.3847/1538-4357/acc52e.
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Abstract The galaxy group NGC 6338 is one of the most violent group–group mergers known to date. While the central dominant galaxies rush at each other at 1400 km s−1 along the line of sight, with dramatic gas heating and shock fronts detected, the central gas in the BCGs remains cool. There are also indications of feedback from active galactic nuclei, and neither subcluster core has been disrupted. With our deep radio uGMRT data at 383 and 650 MHz, we clearly detect a set of large, old lobes in the southern BCG coinciding with the X-ray cavities, while the northern and smaller BCG appears slightly extended in the radio. The southern BCG also hosts a smaller younger set of lobes perpendicular to the larger lobes, but also coinciding with the inner X-ray cavities and matching the jet direction in the parsec-resolution VLBA image. Our spectral analysis confirms the history of two feedback cycles. The high radio frequency analysis classifies the compact source in the southern BCG with a power law, while ruling out a significant contribution from accretion. The radio lightcurve over three decades shows a change about 10 yr ago, which might be related to ongoing feedback in the core. The southern BCG in the NGC 6338 merger remains another prominent case where the direction of jet-mode feedback between two cycles changed dramatically.
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Cielo, S., A. Babul, V. Antonuccio-Delogu, J. Silk i M. Volonteri. "Feedback from reorienting AGN jets". Astronomy & Astrophysics 617 (wrzesień 2018): A58. http://dx.doi.org/10.1051/0004-6361/201832582.
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Aims. We test the effects of re-orienting jets from an active galactic nucleus (AGN) on the intracluster medium in a galaxy cluster environment with short central cooling time. We investigate both the appearance and the properties of the resulting cavities, and the efficiency of the jets in providing near-isotropic heating to the cooling cluster core. Methods. We use numerical simulations to explore four models of AGN jets over several active/inactive cycles. We keep the jet power and duration fixed across the models, varying only the jet re-orientation angle prescription. We track the total energy of the intracluster medium (ICM) in the cluster core over time, and the fraction of the jet energy transferred to the ICM. We pay particular attention to where the energy is deposited. We also generate synthetic X-ray images of the simulated cluster and compare them qualitatively to actual observations. Results. Jets whose re-orientation is minimal (≲20°) typically produce conical structures of interconnected cavities, with the opening angle of the cones being ~15–20°, extending to ~300 kpc from the cluster centre. Such jets transfer about 60% of their energy to the ICM, yet they are not very efficient at heating the cluster core, and even less efficient at heating it isotropically, because the jet energy is deposited further out. Jets that re-orientate by ≳20° generally produce multiple pairs of detached cavities. Although smaller, these cavities are inflated within the central 50 kpc and are more isotropically distributed, resulting in more effective heating of the core. Such jets, over hundreds of millions of years, can deposit up to 80% of their energy precisely where it is required. Consequently, these models come the closest in terms of approaching a heating/cooling balance and mitigating runaway cooling of the cluster core even though all models have identical jet power/duration profiles. Additionally, the corresponding synthetic X-ray images exhibit structures and features closely resembling those seen in real cool-core clusters.
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Donders, Timme, Konstantinos Panagiotopoulos, Andreas Koutsodendris, Adele Bertini, Anna Maria Mercuri, Alessia Masi, Nathalie Combourieu-Nebout i in. "1.36 million years of Mediterranean forest refugium dynamics in response to glacial–interglacial cycle strength". Proceedings of the National Academy of Sciences 118, nr 34 (16.08.2021): e2026111118. http://dx.doi.org/10.1073/pnas.2026111118.
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The sediment record from Lake Ohrid (Southwestern Balkans) represents the longest continuous lake archive in Europe, extending back to 1.36 Ma. We reconstruct the vegetation history based on pollen analysis of the DEEP core to reveal changes in vegetation cover and forest diversity during glacial–interglacial (G–IG) cycles and early basin development. The earliest lake phase saw a significantly different composition rich in relict tree taxa and few herbs. Subsequent establishment of a permanent steppic herb association around 1.2 Ma implies a threshold response to changes in moisture availability and temperature and gradual adjustment of the basin morphology. A change in the character of G–IG cycles during the Early–Middle Pleistocene Transition is reflected in the record by reorganization of the vegetation from obliquity- to eccentricity-paced cycles. Based on a quantitative analysis of tree taxa richness, the first large-scale decline in tree diversity occurred around 0.94 Ma. Subsequent variations in tree richness were largely driven by the amplitude and duration of G–IG cycles. Significant tree richness declines occurred in periods with abundant dry herb associations, pointing to aridity affecting tree population survival. Assessment of long-term legacy effects between global climate and regional vegetation change reveals a significant influence of cool interglacial conditions on subsequent glacial vegetation composition and diversity. This effect is contrary to observations at high latitudes, where glacial intensity is known to control subsequent interglacial vegetation, and the evidence demonstrates that the Lake Ohrid catchment functioned as a refugium for both thermophilous and temperate tree species.
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Irving, Zackery A., Steven H. Saar, Bradford J. Wargelin i José-Dias do Nascimento. "Stellar Cycles in Fully Convective Stars and a New Interpretation of Dynamo Evolution". Astrophysical Journal 949, nr 2 (1.06.2023): 51. http://dx.doi.org/10.3847/1538-4357/acc468.
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Abstract An αΩ dynamo, combining shear and cyclonic convection in the tachocline, is believed to generate the solar cycle. However, this model cannot explain cycles in fast rotators (with minimal shear) or in fully convective stars (no tachocline); an analysis of these stars could therefore provide key insights into how these cycles work. We reexamine ASAS data for 15 M dwarfs, 11 of which are presumed fully convective; the addition of newer ASAS-SN data confirms cycles in roughly 12 of them, while presenting new or revised rotation periods for 5 stars. The amplitudes and periods of these cycles follow A cyc ∝ P cyc 0.94 ± 0.11 , with P cyc/P rot ∝ Ro −1.02±0.06 (where Ro is the Rossby number), very similar to P cyc/P rot ∝ Ro −0.81±0.17 that we find for 40 previously studied FGK stars, although P cyc/P rot and α are a factor of ∼20 smaller in the M stars. The very different P cyc/P rot–Ro relation seen here compared to previous work suggests that two types of dynamo, with opposite Ro dependences, operate in cool stars. Initially, a (likely α 2 or α 2Ω) dynamo operates throughout the convective zone in mid- to late-M and fast-rotating FGK stars, but once magnetic breaking decouples the core and convective envelope, a tachocline αΩ dynamo begins and eventually dominates in older FGK stars. A change in α in the tachocline dynamo generates the fundamentally different P cyc/P rot–Ro relation.
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Walker, Anthony, Matthew Driller, Matt Brearley, Christos Argus i Ben Rattray. "Cold-water immersion and iced-slush ingestion are effective at cooling firefighters following a simulated search and rescue task in a hot environment". Applied Physiology, Nutrition, and Metabolism 39, nr 10 (październik 2014): 1159–66. http://dx.doi.org/10.1139/apnm-2014-0038.
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Firefighters are exposed to hot environments, which results in elevated core temperatures. Rapidly reducing core temperatures will likely increase safety as firefighters are redeployed to subsequent operational tasks. This study investigated the effectiveness of cold-water immersion (CWI) and iced-slush ingestion (SLUSH) to cool firefighters post-incident. Seventy-four Australian firefighters (mean ± SD age: 38.9 ± 9.0 years) undertook a simulated search and rescue task in a heat chamber (105 ± 5 °C). Testing involved two 20-min work cycles separated by a 10-min rest period. Ambient temperature during recovery periods was 19.3 ± 2.7 °C. Participants were randomly assigned one of three 15-min cooling protocols: (i) CWI, 15 °C to umbilicus; (ii) SLUSH, 7 g·kg−1 body weight; or (iii) seated rest (CONT). Core temperature and strength were measured pre- and postsimulation and directly after cooling. Mean temperatures for all groups reached 38.9 ± 0.9 °C at the conclusion of the second work task. Both CWI and SLUSH delivered cooling rates in excess of CONT (0.093 and 0.092 compared with 0.058 °C·min−1) and reduced temperatures to baseline measurements within the 15-min cooling period. Grip strength was not negatively impacted by either SLUSH or CONT. CWI and SLUSH provide evidence-based alternatives to passive recovery and forearm immersion protocols currently adopted by many fire services. To maximise the likelihood of adoption, we recommend SLUSH ingestion as a practical and effective cooling strategy for post-incident cooling of firefighters in temperate regions.
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Stevens, Lora R., Jeffery R. Stone, Josh Campbell i Sherilyn C. Fritz. "A 2200-yr record of hydrologic variability from Foy Lake, Montana, USA, inferred from diatom and geochemical data". Quaternary Research 65, nr 02 (marzec 2006): 264–74. http://dx.doi.org/10.1016/j.yqres.2005.08.024.
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AbstractA 2200-yr long, high-resolution (∼5 yr) record of drought variability in northwest Montana is inferred from diatoms and δ18O values of bio-induced carbonate preserved in a varved lacustrine core from Foy Lake. A previously developed model of the diatom response to lake-level fluctuations is used to constrain estimates of paleolake levels derived from the diatom data. High-frequency (decadal) fluctuations in the de-trended δ18O record mirror variations in wet/dry cycles inferred from Banff tree-rings, demonstrating the sensitivity of the oxygen-isotope values to changes in regional moisture balance. Low frequency (multi-centennial) isotopic changes may be associated with shifts in the seasonal distribution of precipitation. From 200 B.C. to A.D. 800, both diatom and isotope records indicate that climate was dry and lake level low, with poor diatom preservation and high organic carbon: nitrogen ratios. Subsequently, lake level rose slightly, although the climate was drier and more stable than modern conditions. At A.D. 1200, lake level increased to approximately 6 m below present elevation, after which the lake fluctuated between this elevation and full stage, with particularly cool and/or wetter conditions after 1700. The hydrologic balance of the lake shifted abruptly at 1894 because of the establishment of a lumber mill at the lake's outlet. Spectral analysis of the δ18O data indicates that severe droughts occurred with multi-decadal (50 to 70 yr) frequency.
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Desprat, S., M. F. Sánchez Goñi, J. F. McManus, J. Duprat i E. Cortijo. "Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence". Climate of the Past 5, nr 1 (6.03.2009): 53–72. http://dx.doi.org/10.5194/cp-5-53-2009.
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Abstract. We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago, a time period centred on Marine Isotope Stage (MIS) 9 and characterized by particular baseline climate states. This study enables the documentation of vegetation changes in the north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appear more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition, which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the Southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appear to be related to changes in deep water circulation and probably to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in Southern Europe.
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Desprat, S., M. F. Sánchez Goñi, J. Duprat, E. Cortijo i J. F. McManus. "Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence". Climate of the Past Discussions 4, nr 2 (28.03.2008): 375–414. http://dx.doi.org/10.5194/cpd-4-375-2008.
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Abstract. We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago a time period centred on Marine Isotope Stage (MIS) 9 and characterised by particular baseline climate states. This study enables to document the vegetation changes in north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appears more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appears related to changes in deep water circulation and likely to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of a pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in southern Europe.
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Chubarenko, Irina. "Physical processes behind interactions of microplastic particles with natural ice". Environmental Research Communications 4, nr 1 (1.01.2022): 012001. http://dx.doi.org/10.1088/2515-7620/ac49a8.
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Abstract Microplastic particles (MPs, <5 mm) are found in marine ice in larger quantities than in seawater, however, the distribution pattern within the ice cores is not consistent. To get insights into the most general physical processes behind interactions of ice and plastic particles in cool natural environments, information from academic and applied research is integrated and verified against available field observations. Non-polar molecules of common-market plastics are hydrophobic, so MPs are weak ice nucleators, are repelled from water and ice, and concentrate within air bubbles and brine channels. A large difference in thermal properties of ice and plastics favours the concentration of MPs at the ice surface during freeze/thaw cycles. Under low environmental temperatures, falling in polar regions below the glass / brittle-ductile transition temperatures of the common-use plastics, they become brittle. This might partially explain the absence of floating macroplastics in polar waters. Freshwater freezes at a temperature well below that of its maximum density, so the water column is stably stratified, and MPs eventually concentrate at the ice surface and in air bubbles. In contrast, below growing sea ice, mechanisms of suspension freezing under conditions of (thermal plus haline) convection should permanently entangle MPs into ice. During further sea ice growth and aging, MPs are repelled from water and ice into air bubbles, brine channels, and to the upper/lower boundaries of the ice column. Sea ice permeability, especially while melting periods, can re-distribute sub-millimeter MPs through the brine channels, thus potentially introducing the variability of contamination with time. In accord with field observations, analysis reveals several competing factors that influence the distribution of MPs in sea ice. A thorough sampling of the upper ice surface, prevention of brine leakage while sampling and handling, considering the ice structure while segmenting the ice core—these steps may be advantageous for further understanding the pattern of plastic contamination in natural ice.
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Natvig, Erin E., Steven C. Ingham, Barbara H. Ingham, Leslie R. Cooperband i Teryl R. Roper. "Salmonella enterica Serovar Typhimurium and Escherichia coli Contamination of Root and Leaf Vegetables Grown in Soils with Incorporated Bovine Manure". Applied and Environmental Microbiology 68, nr 6 (czerwiec 2002): 2737–44. http://dx.doi.org/10.1128/aem.68.6.2737-2744.2002.
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ABSTRACT Bovine manure, with or without added Salmonella enterica serovar Typhimurium (three strains), was incorporated into silty clay loam (SCL) and loamy sand (LS) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. The S. enterica serovar Typhimurium inoculum was 4 to 5 log CFU/g in manure-fertilized soil. The conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily average Madison, Wis., weather conditions (hourly temperatures, rainfall, daylight, and humidity) for a 1 March or a 1 June manure application and subsequent vegetable growing seasons ending 9 August or 28 September, respectively. Core soil samples were taken biweekly from both inoculated and uninoculated soil beds in each chamber. Radishes, arugula, and carrots were planted in soil beds, thinned, and harvested. Soils, thinned vegetables, and harvested vegetables were analyzed for S. enterica serovar Typhimurium and Escherichia coli (indigenous in manure). After the 1 March manure application, S. enterica serovar Typhimurium was detected at low levels in both soils on 31 May, but not on vegetables planted 1 May and harvested 12 July from either soil. After the 1 June manure application, S. enterica serovar Typhimurium was detected in SCL soil on 7 September and on radishes and arugula planted in SCL soil on 15 August and harvested on 27 September. In LS soil, S. enterica serovar Typhimurium died at a similar rate (P ≥ 0.05) after the 1 June manure application and was less often detected on arugula and radishes harvested from this soil compared to the SCL soil. Pathogen levels on vegetables were decreased by washing. Manure application in cool (daily average maximum temperature of <10°C) spring conditions is recommended to ensure that harvested vegetables are not contaminated with S. enterica serovar Typhimurium. Manure application under warmer (daily average maximum temperature >20°C) summer conditions is not recommended when vegetable planting is done between the time of manure application and late summer. A late fall manure application will not increase the risk of contaminating vegetables planted the next spring, since further experiments showed that repeated freeze-thaw cycles were detrimental to the survival of S. enterica serovar Typhimurium and E. coli in manure-fertilized soil. The number of indigenous E. coli in soil was never significantly lower (P < 0.05) than that of S. enterica serovar Typhimurium, suggesting its usefulness as an indicator organism for evaluating the risk of vegetable contamination with manure-borne S. enterica serovar Typhimurium.
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Shakir, Arwa Ossama, i Haifaa Abd Al-Rasool Ali. "The Effect of Lining Material on the Permeability of Clayey Soil". Civil Engineering Journal 5, nr 3 (19.03.2019): 662. http://dx.doi.org/10.28991/cej-2019-03091277.
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The main objectives of current work are to reduce the permeability of clayey soil for different fluid (water and crude oil) and to predict its efficiency for petroleum storage. Current research uses a sodium bentonite (B) with percentage (1.5, 3 and 6%) by the dry weight of soil and coal tar extended epoxy resin coating as the lining material. The soil sample was brought from AL -Nahrawan region. Soil's permeability for petrol was studied through using compacted soil model and making a central hole (core) in it with changing its dimensions (diameter, thickness of wall and base), type of fluid and number of filling cycles. After filling the core with these fluids, the volume losses of fluids were measured per day. When two cycles were finished, a sample was taken from the base of the core to be examined in a consolidation test. Number of laboratory tests have been conducted such as (Atterberg limits, compaction test, consolidation, sieve analysis and specific gravity).The results showed that the increase in bentonite percentage causes an increase in (optimum moisture content, Atterberg limit and specific gravity) and also decreasing in (max dry unit weight and permeability) as the fluid was water. However, an increase in permeability was obtained using the crude oil. A reduction in volume losses was observed when using the lining material, coal tar extended epoxy resin coating.
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Guo, Zhenghuai, Klaus Regenauer-Lieb, Phung Nhu Hao Vu i Zhenliang Guan. "Characteristics of Elastoplastic Consolidation by Compaction and Its Effects on Coal Permeability". Energies 15, nr 20 (17.10.2022): 7647. http://dx.doi.org/10.3390/en15207647.
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This paper presents a combined experimental–analytical investigation of coal strain development under fluctuating applied hydrostatic stress. The laboratory setup mimics the isotropic volumetric compaction of coal under burial–uplift cycles in the absence of tectonic stress. Special emphasis is placed on the corresponding permeability evolution of the coal strata. Our results show that the stress–strain path is exponential, approaching a linear relation in the logarithmic stress–strain space with the monotonic increase in stress. A similar behavior is found for the strain–permeability path in the logarithmic strain–permeability space. The permeability recovery undergoes hysteresis with respect to the stress in a stress loading–unloading cycle, but the hysteresis is not manifest with respect to the strain. A theoretical geomechanical consolidation analysis was performed using an elastoplastic modelling framework. The analysis suggests that plastic strain is the cause of the hysteresis of the strain recovery in a stress loading–unloading cycle. The closed hysteresis loops manifested in stress loading–unloading–reloading cycles are promoted by the plastic strain during stress unloading and the difference in evolution rates of the elastic core between loading and unloading. The results of this study are helpful for understanding the mechanism of permeability evolution and optimizing water and coal seam gas production.
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Li, Yan, Guoshun Wang, Zhaohao Li, Jiahai Yuan, Dan Gao i Heng Zhang. "A Life Cycle Analysis of Deploying Coking Technology to Utilize Low-Rank Coal in China". Sustainability 12, nr 12 (15.06.2020): 4884. http://dx.doi.org/10.3390/su12124884.
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At present, the excess capacity in China’s coke industry can be deployed to utilize some low-rank coal, replacing coking coal with potential economic gains, energy efficiency, and environmental benefits. This study presents a life cycle analysis to model these potential benefits by comparing a metallurgical coke technical pathway with technical pathways of gasification coke integrated with different chemical productions. The results show that producing gasification coke is a feasible technical pathway for the transformation and development of the coke industry. However, its economic feasibility depends on the price of cokes and coals. The gasification coke production has higher energy consumption and CO2 emissions because of its lower coke yield. Generally speaking, using gasification coke to produce F-T oils has higher economic benefits than producing methanol, but has lower energy efficiency and higher carbon emissions.
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Liang, Ji Wei, Ruo Gu Wang i Zhen Jun Liu. "Base Level Cycle and Coal-Accumulation of Lower Member of Shanxi Formation of Permian in Northeast Part Ordos Basin". Advanced Materials Research 524-527 (maj 2012): 266–73. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.266.
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Coal accumulation of Lower Member of Shanxi Formation in Northwest part of Ordos basin has been researched according to the principle of base level cycle based on outcrops, core description, and well log. Sedimentary face analysis, base level correlation, condense data controlling mapping were adopted. Coal forming has a close relation to base level cycle, face distribution, and coal-forming latter stage of short-term base level ascending cycle. Coal measure distribution has a complementary relationship with distributary channel. In peat swamp far from distributary channel, coal layer has greater thickness, with lower ash content, and lack of waste rock interlayer. Near the distributary channel, coal layer is thinner and sparsely-distributed, with high ash content, and transition to clastic rock. From shan23 to shan21, thick coal layer has a trend of retreat towards north, showing that the lower member of Shanxi Formation constitutes mid-term base level ascending cycle.
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Li, Ranran, Jieyi Yu, Asif Shah, Xinglong Dong, Xiaona Li, Hongtao Yu, Xie Quan i Youngguan Jung. "Novel in situ Synthesized Fe@C Magnetic Nanocapsules Used as Adsorbent for Removal of Organic Dyes and its Recycling". Nano 11, nr 02 (luty 2016): 1650013. http://dx.doi.org/10.1142/s1793292016500132.
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Core/shell type carbon-coated Fe nanocapsules (Fe@C NCs) were in situ synthesized by DC arc-discharge plasma method in methane atmosphere. Such Fe nanocapsules have saturation magnetization of 29.32[Formula: see text]emu/g and specific surface area of 85.86[Formula: see text]m2/g. The carbon shell of Fe@C NCs was functionalized with oxygen-containing groups (such as –OH or –COOH) by using H2O2. The adsorption of organic dye, e.g., methylene blue (MB) was systematically investigated in different conditions, such as contact time, pH values and temperature. The maximum adsorption capacity (46.5[Formula: see text]mg/g) was calculated by fitting the adsorption isotherms with Langmuir model, coincident with the experimental result of 44.5[Formula: see text]mg/g. Kinetics data supported pseudo-second order model, and the thermodynamic process of adsorption was revealed as endothermic and spontaneous physisorption. The MB-absorbed Fe@C NCs can be entirely separated from the contaminative solution by a magnetic field and then successfully cycled for regeneration. After repetitive cycles of the adsorption/desorption experiments for five times, the removal efficiency can be maintained over 90%.
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Horoshkova, L., Y. Khlobystov i V. Volkov. "CYCLICAL NATURE OF THE COAL MINING INDUSTRY IN UKRAINE AND ITS SUSTAINABLE DEVELOPMENT CAPACITY". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 3 (90) (2020): 54–61. http://dx.doi.org/10.17721/1728-2713.90.08.
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The mechanism for Ukrainian coal mining industry's sustainable development management has been formed as a result of the study. Significant losses in the process of coal mining are proved to be one of the coal mining industry problems. It has been specified that the reserve for the industry's efficiency upgrading in the framework of more resource-saving behaviour is funding of mines reconstruction. Slowdown in the coal mining industry development has been determined to be the result of military operation in Donets'k and Luhans'k regions. The inefficiency of transport logistics for coal resources imported by Ukraine has been proved, since the rail freight transport is favored instead of cheaper maritime transport due to the underdeveloped quality of port infrastructure. Balancing mining, production of coal raw materials and their subsequent use in the production processes have been proved to be the ways to ensure rational use of coal resources of Ukraine. The processes for coking coal is metal production, and for anthracite – thermal energy production. Relationship between growth rates of coking coal mining and production, coke mining, exports and imports of coke and ironmaking during 2008– 2017s have been studied. It has been demonstrated that imports of coking coal essentially depends on the market pricing and has little to do with the needs of the metallurgical industry of Ukraine. It has been shown that the system for rational use of coking coal's capacity in Ukraine should include balancing flows of coal mining, coke and semi-coke mining according to the needs of national metallurgical industry, taking into account cyclical nature of its development. The necessity of coordinating the volumes of anthracite extraction, production and consumption and taking into account short cycles of heat power development have been defined.
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Xia, Jing, Shuxiang Li, Yuan Gao, Dakui Zhang, Qiongguang Li i Yanhong Wang. "Silicon/Needle Coke Composites as Efficient Anodes for Lithium Ion Batteries". MATEC Web of Conferences 363 (2022): 01022. http://dx.doi.org/10.1051/matecconf/202236301022.
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In this research, a facile method was reported to prepare silicon/carbon composites by heating Si nanosheets and coal-based needle cokes in the assistance of binder glucopyranose. The microstructures and electrochemical performances of samples were analyzed. It was found that Si nanosheets adhered to needle cokes forming silicon/carbon composites. Compared with needle cokes, the composites showed higher capacity and initial coulombic efficiency. Also, they improved the cycle stability of silicon materials. The silicon/carbon anode had a reversible capacity of 381.8 mAh/g at a current density of 100 mA/g after 170 cycles. In our work, relatively inexpensive Si nanosheets and coal-based needle cokes with low price were employed as the silicon and carbon sources respectively. Therefore, this method provides a possible strategy to reduce costs of silicon/carbon anodes, accelerating their commercial applications.
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Biava, Nadia, Marisa Brienza, Annalisa Bonafede, Myriam Gitti, Etienne Bonnassieux, Jeremy Harwood, Alastair C. Edge, Christopher J. Riseley i Adrian Vantyghem. "Constraining the AGN duty cycle in the cool-core cluster MS 0735.6+7421 with LOFAR data". Astronomy & Astrophysics 650 (czerwiec 2021): A170. http://dx.doi.org/10.1051/0004-6361/202040063.
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Context. MS 0735.6+7421 is a galaxy cluster that hosts a central radio galaxy with a very steep spectrum. The spectrum is produced by one of the most powerful known jetted active galactic nuclei (AGN). The radio plasma, ejected at nearly light speed from the central AGN, has displaced the intra-cluster medium, leaving two pairs of cavities observable in the X-ray. The cavities are associated with two different outbursts and have distributed energy to the surrounding medium. While the age of the cavities has previously been estimated from the X-rays, no confirmation from radio data is available. Furthermore, the radio spectrum has only been derived from integrated flux density measurements so far, and the spatial distribution that would help us to understand the nature of this source is still lacking. Aims. We perform for the first time a detailed, high-resolution spectral study of the source at radio frequencies and investigate its duty cycle. We compare this with previous X-ray estimates. Methods. We used new observations at 144 MHz produced with the LOw Frequency ARray (LOFAR) together with archival data at higher frequencies (235, 325, 610, 1400, and 8500 MHz), to investigate the spectral properties of the source. We also used radiative models to constrain the age of the source. Results. At the LOFAR frequency, the source presents two large outer radio lobes that are wider than at higher frequencies, and a smaller intermediate lobe that is located south-west of the core. A new inspection of X-ray data allowed us to identify an intermediate cavity that is associated with this lobe. It indicates a further phase of jet activity. The radio lobes have a steep spectrum even at LOFAR frequencies, reaching α144610 = 2.9 in the outer lobes and α144610 = 2.1 in the intermediate lobe. Fitting the lobe spectra using a single injection model of particle ageing, we derived a total age of the source between 170 and 106 Myr. This age agrees with the buoyancy and sound-crossing timescales derived from X-ray data. The resolution of the spectral age map we performed allows us to reconstruct the duty cycle of the source. In three phases of jet activity, the AGN was active for most of the time with only brief quiescent phases that ensured the repeated heating of the central gas. Finally, we estimated the minimum energy inside the outer lobes. We find that a source of additional pressure support must be present to sustain the bubbles against the pressure of the external medium.
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Pasini, T., M. Gitti, F. Brighenti, E. O’Sullivan, F. Gastaldello, P. Temi i S. L. Hamer. "A First Chandra View of the Cool Core Cluster A1668: Offset Cooling and AGN Feedback Cycle". Astrophysical Journal 911, nr 1 (1.04.2021): 66. http://dx.doi.org/10.3847/1538-4357/abe85f.
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Morcote, Anyela, Gary Mavko i Manika Prasad. "Dynamic elastic properties of coal". GEOPHYSICS 75, nr 6 (listopad 2010): E227—E234. http://dx.doi.org/10.1190/1.3508874.
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Laboratory ultrasonic velocity measurements of different types of coal demonstrate that their dynamic elastic properties depend on coal rank and applied effective pressure. In spite of the growing interest in coal beds as targets for methane production, the high abundance in sedimentary sequences and the strong influence that they have on seismic response, little data are available on the acoustic properties of coal. Velocities were measured in core plugs parallel and perpendicular to lamination surfaces as a function of confining pressure up to [Formula: see text] in loading and unloading cycles. P- and S-wave velocities and dry bulk and dry shear moduli increase as coal rank increases. Thus, bituminous coal and cannel show lower velocities and moduli than higher ranked coals such as semianthracite and anthracite. The [Formula: see text] relationship for dry samples is linear and covers a relatively wide range of effective pressures and coal ranks. However, there is a pressure dependence on the elastic properties of coal for confining pressures below [Formula: see text]. This pressure sensitivity is related to the presence of microcracks. Finally, the data show that coal has an intrinsic anisotropy at confining pressures above [Formula: see text], the closing pressure for most of the microcracks. This intrinsic anisotropy at high pressures might be due to fine lamination and preferred orientation of the macerals.
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Nagarkatti, Arun, i Ajit Kumar Kolar. "Assessment of Life Cycle Greenhouse Gas Emissions from Coal Fired Power Plants in India". Applied Mechanics and Materials 704 (grudzień 2014): 487–90. http://dx.doi.org/10.4028/www.scientific.net/amm.704.487.
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More than two third share of electricity come from coal fired power plants in India. Coal fired power plants are the largest source of anthropogenic CO2 emissions per unit of electricity generation among all fossil fuel based power plants. There has been climate change and global warming globally due to increasing anthropogenic emission of greenhouse gas (GHG) into the atmosphere. This paper examines life cycle GHG emission such as CH4, CO2 and N2O of a National Thermal Power Corporation (NTPC) Limited power plant using life cycle approach. The various stages involved in the assessment of life cycle GHG emissions in the present study include coal mining, transportation of coal to the power plant and coal combustion for electricity generation. The results show that direct CO2 emission from coal combustion is about 890 g CO2-e/kWh, whereas life cycle GHG emissions amount to 929.1 g CO2-e/kWh. Indirect GHG emissions add up to 4.2% of total emissions. Coal mine methane leakage into atmosphere in India is low since more than 90% of the coal mining is surface mining.
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Chen, Ling-Xiao, Shi-Jun Yin, Tong-Qing Chai, Jia-Li Wang, Guo-Ying Chen, Xi Zhou i Feng-Qing Yang. "Ultra-High Adsorption Capacity of Core–Shell-Derived Magnetic Zeolite Imidazolate Framework-67 as Adsorbent for Selective Extraction of Theophylline". Molecules 28, nr 14 (21.07.2023): 5573. http://dx.doi.org/10.3390/molecules28145573.
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A core–shell-derived structural magnetic zeolite imidazolate framework-67 (Fe3O4-COOH@ZIF-67) nanocomposite was fabricated through a single-step coating of zeolite imidazolate framework-67 on glutaric anhydride-functionalized Fe3O4 nanosphere for the magnetic solid-phase extraction (MSPE) of theophylline (TP). The Fe3O4-COOH@ZIF-67 nanocomposite was characterized through scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, Zeta potential analysis, X-ray diffraction, Brunauer–Emmett–Teller, and vibrating sample magnetometer. The material has a high specific surface area and good magnetism, which maintains the regular dodecahedron structure of ZIF-67 without being destroyed by the addition of Fe3O4-COOH nanospheres. The Fe3O4-COOH@ZIF-67 can rapidly adsorb TP mainly through the strong coordination interaction between undercoordinated Co2+ on ZIF-67 and –NH from imidazole of TP. The adsorption and desorption conditions, such as the amount of adsorbent, adsorption time, pH value, and elution solvent, were optimized. The kinetics of TP adsorption on Fe3O4-COOH@ZIF-67 was found to follow pseudo-second-order kinetics. The Langmuir model fits the adsorption data well and the maximum adsorption capacity is 1764 mg/g. Finally, the developed MSPE-HPLC method was applied in the enrichment and analysis of TP in four tea samples and rabbit plasma. TP was not detected in oolong tea and rabbit plasma, and its contents in jasmine tea, black tea, and green tea are 5.80, 4.31, and 1.53 μg/g, respectively. The recoveries of spiked samples are between 74.41% and 86.07% with RSD in the range of 0.81–3.83%. The adsorption performance of Fe3O4-COOH@ZIF-67 nanocomposite was nearly unchanged after being stored at room temperature for at least 80 days and two consecutive adsorption–desorption cycles. The results demonstrate that Fe3O4-COOH@ZIF-67 nanocomposite is a promising magnetic adsorbent for the preconcentration of TP in complex samples.
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Zhao, Li, i Xiangdong Xu. "The development of Coke Carried-Heat Gasification Coal-Fired Combined Cycle". Journal of Thermal Science 8, nr 4 (grudzień 1999): 270–76. http://dx.doi.org/10.1007/s11630-999-0016-6.
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Villar, Álvaro Alejandro, i Edwar Herrera. "Reservoir quality and petrophysical evaluation of the Paleocene paralic sandstones in the Ranchería sub-basin, Colombia". Boletín de la Sociedad Geológica Mexicana 73, nr 1 (1.04.2021): A151220. http://dx.doi.org/10.18268/bsgm2021v73n1a151220.
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The Ranchería sub-basin is an unexplored basin which gives a valuable opportunity to find new perspectives about the hydrocarbon potential in Colombia. The sandy facies of the Paleocene Cerrejón Formation accomplish with the characteristics within the petroleum system, to be considered as a potential reservoir rock. This work aims to evaluate the reservoir quality of the Cerrejón Formation using three cored wells, through the integration of well logs, core sedimentological descriptions, porosity and permeability lab data, and thin-sections analysis. Using GR log patterns and sedimentary cycles, four facies associations (A,B,C,D) were defined associated to an environment of a deltaic plain complex. The well correlation was performed using the sedimentary cycles methodology. Five petrophysical rock-types (mudstone (M), coal (P), sandy mudstone (sM), muddy sandstone (mS), and sandstone (S)) were identified, according to textural and lithological features from the core descriptions, adjusted with well logs analysis and NTG ratio. A supervised neural network model of electrofacies was generated with the GR, RHOB, NPHI, and DT logs combination, using as training curves the wells B and C. The blind test validation was executed in the well C with an 82% of correlation. Petrophysical evaluation was performed calculating shale volume, effective porosity, permeability and water saturation. Reservoir rock properties are fair to moderate with porosities between 0.3-22.9 %, and permeability values that range from 0.02mD to 47mD. The interest intervals average water saturations vary between 0.3 and 0.5. Four hydraulic flow units were estimated with the Winland’s R35 method for the assessment of reservoir quality. There is not a clear relationship between F.A. and HFUs for the Cerrejón Formation, however, the F.A. B comprises the HFUs with the best petrophysical properties. The reservoir quality of Cerrejón Formation is controlled mainly for diagenetic and compositional processes than related to primary deposition. The diagenetic controls in reservoir properties are the calcite cementation, quartz overgrowth, pseudomatrix presence, and feldspar and calcite dissolution. This integrated study provides a good approximation to the understanding of the Cerrejón Formation and the evidence of a moderate reservoir quality.
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Chen, Chun-Ti, i Marc-Jan Gubbels. "TgCep250 is dynamically processed through the division cycle and is essential for structural integrity of the Toxoplasma centrosome". Molecular Biology of the Cell 30, nr 10 (maj 2019): 1160–69. http://dx.doi.org/10.1091/mbc.e18-10-0608.
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The apicomplexan centrosome has a unique bipartite structure comprising an inner and outer core responsible for the nuclear cycle (mitosis) and budding cycles (cytokinesis), respectively. Although these two cores are always associated, they function independently to facilitate polyploid intermediates in the production of many progeny per replication round. Here, we describe the function of a large coiled-coil protein in Toxoplasma gondii, TgCep250, in connecting the two centrosomal cores and promoting their structural integrity. Throughout the cell cycle, TgCep250 localizes to the inner core but, associated with proteolytic processing, is also present on the outer core during the onset of cell division. In the absence of TgCep250, stray centrosome inner and outer core foci were observed. The detachment between centrosomal inner and outer cores was found in only one of the centrosomes during cell division, indicating distinct states of mother and daughter centrosomes. In mammals, Cep250 processing is required for centrosomal splitting and is mediated by Nek phopsphorylation. However, we show that neither the nonoverlapping spatiotemporal localization of TgNek1 and TgCep250 nor the distinct phenotypes upon their respective depletion support conservation of this mechanism in Toxoplasma. In conclusion, TgCep250 has a tethering function tailored to the unique bipartite centrosome in the Apicomplexa.
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Anselm, Reiner, Johannes Fischer, Wolfgang Lienemann i Hans-Richard Reuter. "Der Bologna-Prozess als Herausforderung für die theologische Ethik". Zeitschrift für Evangelische Ethik 49, nr 1 (1.02.2005): 169–89. http://dx.doi.org/10.14315/zee-2005-0125.
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Abstract The Bologna process forces a reframing of the theological education. In the autor's mind, it affords chances for an improved quality during the first two cycles. The change from an input-oriented to an output-oriented leaming provides a better professional competences. In addition, the Bologna process provokes to profile theology in an interdisciplinary context. The article outlines the profile of Theological Ethics as a self-contained discipline, connectedwith both, the other theolgical disciplines and the adjacent sciences, such as medicine, law, and sociology. According to this, the authors discuss the advantages and the risks ofthe two-cylcle, BA/MA education and draw the conclusions for the further curriculas in theological ethics. A coml)lon competence-based core-curriculum is presented in order to get joint standards and to improve student's mobility.
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Yang, Junyao, i Liangliang Guo. "Dynamic Evaluation of Water Utilization Efficiency in Large Coal Mining Area Based on Life Cycle Sustainability Assessment Theory". Geofluids 2021 (15.09.2021): 1–20. http://dx.doi.org/10.1155/2021/7793988.
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Coal mining enterprises have a variety of water sources, complex drainage structures, long production chain, and many links, which lead to uncoordinated water utilization and low water efficiency. Taking a large coal mining area of China as an example, a dynamic model was established to evaluate the water utilization efficiency based on the Life Cycle Sustainability Assessment (LCSA) theory. In the model, the influence of five aspects (including resources, economy, technology, society, and environment) and 19 factors was considered. The game theory method was adopted to calculate the fusion weights of the 19 factors according to the analytic hierarchy process and CRITIC method. The CW-VIKOR method was used to explain the dynamic evaluation results of water efficiency in the coal mining area. The results show that the environmental impacts of the mining system mainly come from three aspects: regional drainage, domestic sludge landfill and disposal, and water system electricity consumption. Electricity consumption in water systems has the greatest environmental impact, accounting for about 73%, regional drainage for about 26%, and domestic sludge landfill and disposal for about 1%.The CW-VIKOR approach can harmonize the interrelationships among resources, economy, technology, society, and environment. It is an effective method for LCSA of water resource in the coal mining area. The reliability of the evaluation results is high and close to the actual situation. The dynamic model established in this paper is also applicable to other coal mine areas, and only the factor weights need to be modified according to the specific characteristics of each coal mine. The model can provide guidance for optimal exploitation and allocation of coal mine water resources.
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Hikmawaty, Hikmawaty, Eleonora Sofilda i Maria Ariesta Utha. "Analysis of Environmental Management Strategy Based On Life Cycle Analysis In Coal Companies That Won Proper Emas In 2019-2021". Eduvest - Journal of Universal Studies 3, nr 1 (20.01.2023): 110–25. http://dx.doi.org/10.36418/eduvest.v3i1.721.
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This study aims to determine the limitations and application of life cycle analysis in the mining industry as well as recommendations for innovation programs and strategies in supporting environmental performance improvements that have an impact on the acquisition of “Proper emas”, the role of internal and external stakeholders as well as the relationship to the implementation of ISO 26000, especially the environment, governance and good operating practices and achievement of environmental SDGs indicators number 6,7 12 and 13.The data used in this study consists of primary data from coal mining companies receiving Proper Emas for 2019-2021, secondary data from sustainability reports, and annual reports of the companies studied. The research object was 4 (four) coal companies getting Proper Emas and sample was selected using a purposive sampling method in order to obtain 12 respondents were interviwed. This study uses descriptive qualitative analysis. The results of the study show that the scope limitations on coal mining use cradle to gate and are still limited to midpoint criteria covering only direct impacts such as carbon emissions produced, hot spots in the coal mining industry are material removal, especially the use of heavy equipment and the fuel used. The innovation program focuses on hot spots and has succeeded in significantly reducing carbon emissions. The role of internal stakeholders is the key to success in implementing environmental improvement strategies and successfully having an impact on the implementation of the core subject of ISO 26000 environment, good governance and operating practices, and the achievement of SDGs 6,7, 12, and 13
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Hikmawaty, Hikmawaty, Eleonora Sofilda i Maria Ariesta Utha. "Analysis of Environmental Management Strategy Based On Life Cycle Analysis In Coal Companies That Won Proper Emas In 2019-2021". Eduvest - Journal of Universal Studies 3, nr 1 (20.01.2023): 110–25. http://dx.doi.org/10.59188/eduvest.v3i1.721.
Pełny tekst źródłaStreszczenie:
This study aims to determine the limitations and application of life cycle analysis in the mining industry as well as recommendations for innovation programs and strategies in supporting environmental performance improvements that have an impact on the acquisition of “Proper emas”, the role of internal and external stakeholders as well as the relationship to the implementation of ISO 26000, especially the environment, governance and good operating practices and achievement of environmental SDGs indicators number 6,7 12 and 13.The data used in this study consists of primary data from coal mining companies receiving Proper Emas for 2019-2021, secondary data from sustainability reports, and annual reports of the companies studied. The research object was 4 (four) coal companies getting Proper Emas and sample was selected using a purposive sampling method in order to obtain 12 respondents were interviwed. This study uses descriptive qualitative analysis. The results of the study show that the scope limitations on coal mining use cradle to gate and are still limited to midpoint criteria covering only direct impacts such as carbon emissions produced, hot spots in the coal mining industry are material removal, especially the use of heavy equipment and the fuel used. The innovation program focuses on hot spots and has succeeded in significantly reducing carbon emissions. The role of internal stakeholders is the key to success in implementing environmental improvement strategies and successfully having an impact on the implementation of the core subject of ISO 26000 environment, good governance and operating practices, and the achievement of SDGs 6,7, 12, and 13
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Li, Xiaohong, Rony Keppens i Yuhao Zhou. "Coronal Rain in Randomly Heated Arcades". Astrophysical Journal 926, nr 2 (1.02.2022): 216. http://dx.doi.org/10.3847/1538-4357/ac41cd.
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Abstract Adopting the MPI-AMRVAC code, we present a 2.5-dimensional magnetohydrodynamic simulation, which includes thermal conduction and radiative cooling, to investigate the formation and evolution of the coronal rain phenomenon. We perform the simulation in initially linear force-free magnetic fields that host chromospheric, transition-region, and coronal plasma, with turbulent heating localized on their footpoints. Due to thermal instability, condensations start to occur at the loop top, and rebound shocks are generated by the siphon inflows. Condensations fragment into smaller blobs moving downwards, and as they hit the lower atmosphere, concurrent upflows are triggered. Larger clumps show us clear coronal rain showers as dark structures in synthetic EUV hot channels and as bright blobs with cool cores in the 304 Å channel, well resembling real observations. Following coronal rain dynamics for more than 10 hr, we carry out a statistical study of all coronal rain blobs to quantify their widths, lengths, areas, velocity distributions, and other properties. The coronal rain shows us continuous heating–condensation cycles, as well as cycles in EUV emissions. Compared to the previous studies adopting steady heating, the rain happens faster and in more erratic cycles. Although most blobs are falling downward, upward-moving blobs exist at basically every moment. We also track the movement of individual blobs to study their dynamics and the forces driving their movements. The blobs have a prominence-corona transition-region-like structure surrounding them, and their movements are dominated by the pressure evolution in the very dynamic loop system.
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Dongellini, Matteo, Agostino Piazzi, Filippo De Biagi i Gian Luca Morini. "The modelling of reverse defrosting cycles of air-to-water heat pumps with TRNSYS". E3S Web of Conferences 111 (2019): 01063. http://dx.doi.org/10.1051/e3sconf/201911101063.
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The most widespread defrosting technique adopted by Air-Source Heat Pumps (ASHPs) during the heating season is Reverse Cycle Defrosting (RCD). In this paper a dynamic model of RCD, based on performance data provided by the heat pump manufacturer, designed for TRNSYS and with a core-structure suitable for commercial units, is presented. A defrost cycle is divided in three phases. First, the unit heating capacity is reduced as a linear function of the ice layer thickness (Pre-Defrost phase). Subsequently, the reverse cycle operating mode is modelled on the basis of the performance data given by the manufacturer (Defrost phase) and, finally, the heat pump performances are altered taking into account the higher surface temperature of the external coil after the reverse mode (Post-Defrost phase). Then, the influence of defrosting energy losses on the heat pump seasonal performance factor in sites characterized by different climatic conditions has been assessed. Results point out that the ASHP seasonal efficiency decreases of about 5% taking into account defrost energy losses; in addition, the influence of defrost cycles on the internal air temperature is studied by assessing under which conditions the indoor thermal comfort can be guaranteed even in presence of frequent defrost cycles.
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Schurz, Martin, Alexander Laugwitz, Steffen Krzack i Bernd Meyer. "Comparison of Two Coal-Gasifier-Designs with Moving-Bed and Internal-Circulating-Fluidized-Bed Configuration in One Reactor". Open Fuels & Energy Science Journal 10, nr 1 (10.08.2017): 48–67. http://dx.doi.org/10.2174/1876973x01710010048.
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Background:Coal gasification is the promising technology for syngas routes to produce chemicals or transportation fuels. Additionally, it enables clean power generation from coal in Integrated Gasification Combined Cycles (IGCC). So far, coal fines with high ash contents could not be feasibly used in such routes.In this regard, the Internal Circulation gasifier (INCI) is designed to gasify high-ash coal fines efficiently. The staged system is combining a moving bed, a fluidized bed and a jetting fluidized bed in one reaction chamber.Method:The present paper substantially describes the laboratory-scale prototype development in the COORVED-project (“CO2-reduction by innovative gasifier design”) based on the INCI gasification principle of about 50-125 kW thermal input. Information about the gasifiers compounding, especially the reaction chamber, peripheral components and applied measurement systems are given.Results:Experimental results are presented, confirming the targeted, typical flow pattern inside the reaction chamber. Furthermore technical and operational limits of the COORVED prefiguration are discussed. Based on these results a major design change of the reaction chamber is required and explained in detail. Additionally, results of the feedstock variation from coke to lignite are shown.Conclusion:Finally, the operability of the INCI gasification principle is proven by a stationary operating system with controlled ash agglomeration.
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Krajčík, Michal, Michal Masaryk, Martin Šimko i Peter Mlynár. "Possibilities of combining radiant wall cooling with ejector cooling cycle powered by Fresnel solar collectors". E3S Web of Conferences 172 (2020): 03003. http://dx.doi.org/10.1051/e3sconf/202017203003.
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Solar ejector cooling presents an alternative to the commonly used compressor vapour machines. It is a potentially feasible technology for space cooling providing that the temperature of the cooling water is high enough to assure reasonable efficiency of the chiller. This could be achieved by increasing the evaporation temperature of the cooling cycle through its combination with a high-temperature radiant cooling system. We explore the possibilities and benefits of combining a high-temperature radiant wall system with a solar ejector cycle for space cooling of buildings. The lowest water temperature in the wall to prevent condensation was 18°C for the wall with pipes underneath the surface whereas it was 14°C for the wall with pipes embedded in the thermal core. Thus, the evaporation temperature was substantially higher for the radiant systems than for fancoils. For the conventional vapour compressor cooling, this increased the system efficiency (COP) by 30 to 50%. The COP of the ejector cooling cycle was about half of that for the compressor vapour cycle when R1234ze was used as the refrigerant, however, the primary energy was lower for ejector cooling. Using thermally active building systems (TABS) provided a reasonable cool storage capacity for as much as five hours which allows turning the cooling machines off for several hours during peaks in energy demand.
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Zsótér, Brigitta, i Renáta Kaliczka. "Examinations carried out in relation to the shopping habits and satisfaction of costumers in the shops of Coop Szeged LTD." Analecta Technica Szegedinensia 8, nr 1 (11.01.2014): 38–41. http://dx.doi.org/10.14232/analecta.2014.1.38-41.
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Different shop types have different life cycles: introduction, growth, stagnation and decline. The form of supermarkets is in a stage of decline in each EU country.ÂÂÂ For customers coming to the supermarkets of Coop Co., in Szeged is typical to do their shopping every day or more times a week. Shoppers come to do mainly their daily shopping in the shops. The main reasons for choosing them were the wide range of goods and the suitable accessibility of shops. Coop has its own brand which is very popular with customers. There are customers who directly come to the shops to buy products with this brand. Shoppers would extend the range of products with Coop-brand and also would like to see longer opening hours. The customer segment involves people living close to the shops. Our questionnaire survey supports these statements.
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FOLĘGA, Piotr, Dorota BURCHART, Paweł MARZEC, Simona JURSOVA i Pavlina PUSTEJOVSKA. "POTENTIAL ENVIRONMENTAL LIFE CYCLE IMPACTS OF FUEL CELL ELECTRIC VEHICLES POWERED BY HYDROGEN PRODUCED FROM POLISH COKE OVEN GAS". Transport Problems 17, nr 1 (1.03.2022): 151–61. http://dx.doi.org/10.20858/tp.2022.17.1.13.
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This study analysed the greenhouse gas (GHG) emissions of hydrogen fuel cell vehicles’(FCEVs’) life cycles. These included models running on hydrogen derived from coke oven gas (COG), which is a by-product of the coking process of coal and includes hydrogen, methane, and other gases. FCEVs and hydrogen have the potential to drive future mobility. Hydrogen can be separated from the COG in the process of pressure swing adsorption to obtain a purity of hydrogen that meets the requirements of a hydrogen FCEV. An environmental life cycle assessment (LCA) of FCEV powered by hydrogen produced from Polish COG was conducted. The direction of hydrogen production strategies in Poland was also presented. The analyses included the entire life cycle of FCEVs with the production of hydrogen from COG in a Polish coke plant. A comparative analysis of FCEVs and other alternative fuels was conducted, and the main determinants of GHG emissions of FCEV were given. Importantly, this is the first attempt at an environmental assessment of FCEVs in Poland.
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White, Benjamin D., i Helen E. Townley. "Radio Wave-Activated Chemotherapy—A Novel Nanoparticle Thermoresponsive Copolymer Drug Delivery Platform". Materials 16, nr 6 (21.03.2023): 2482. http://dx.doi.org/10.3390/ma16062482.
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Radio waves are highly penetrating, non-ionizing, and cause minimal damage to surrounding tissues. Radio wave control of drug release has been achieved using a novel thermoresponsive copolymer bound to a superparamagnetic iron oxide nanoparticle (SPION) core. A NIPAM-acrylamide-methacrolein copolymer underwent a coil-to-globular structure phase change upon reaching a critical temperature above the human body temperature but below hyperthermic temperatures. The copolymer was covalently bound to SPIONs which increase in temperature upon exposure to radio waves. This effect could be controlled by varying input energies and frequencies. For controlled drug release, proteins were bound via aldehyde groups on the copolymer and amine groups on the protein. The radio wave-induced heating of the complex thereby released the drug-bearing proteins. The fine-tuning of the radio wave exposure allowed multiple cycles of protein-drug release. The fluorescent tagging of the complex by FITC was also achieved in situ, allowing the tagging of the complex. The localization of the complex could also be achieved in vitro under a permanent magnetic field.
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Ulizar, I., i P. Pilidis. "A Semiclosed-Cycle Gas Turbine With Carbon Dioxide–Argon as Working Fluid". Journal of Engineering for Gas Turbines and Power 119, nr 3 (1.07.1997): 612–16. http://dx.doi.org/10.1115/1.2817028.
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This paper describes the performance analysis of a semiclosed-cycle gas turbine. The working fluid is carbon dioxide and the fuel is low heating value gas synthesized from coal. The objective of the machine is to produce clean electricity with the smallest efficiency penalty. First, the thermodynamic properties of the gases in the cycle were obtained as a function of temperature and pressure. Then two performance simulation codes were developed. These have the ability of simulating different configurations of open, closed, and semiclosed cycles. The first code was used for cycle optimization and the second for off-design studies. The design and off-design performances of the machine are predicted. The production of clean electricity will be at the expense of a lower efficiency compared with current equipment. Finally, some critical issues for the development of such a gas turbine are identified.
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Schlesinger, William H., Emily M. Klein i Avner Vengosh. "Global biogeochemical cycle of vanadium". Proceedings of the National Academy of Sciences 114, nr 52 (11.12.2017): E11092—E11100. http://dx.doi.org/10.1073/pnas.1715500114.
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Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 109 g V/y) and extraction and combustion of fossil fuels (600 × 109 g V/y), humans are the predominant force in the geochemical cycle of V at Earth’s surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced—with about 40 × 109 g V/y to 50 × 109 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.
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Hu, Chunlin, i Jing Xie. "The Effect of Multiple Freeze–Thaw Cycles on the Microstructure and Quality of Trachurus murphyi". Foods 10, nr 6 (11.06.2021): 1350. http://dx.doi.org/10.3390/foods10061350.
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Temperature fluctuation in frozen food storage and distribution is the perpetual and core issue faced by the frozen food industry. Ice recrystallisation induced by temperature fluctuations under cold storage causes microstructural changes in fish products and irreversible damages to cells and tissues, which lower the frozen fish quality in the food chain. This study is intended to explore how repeated freezing–thawing affected the microstructure and quality of Trachurus murphyi during its frozen storage. The results showed the consistency between the increase in ice crystal diameter, volume, and porosity in frozen fish and the increase in centrifugal loss (from 22.4% to 25.69%), cooking loss (from 22.32% to 25.19%), conductivity (from 15.28 Ms/cm to 15.70 Ms/cm), TVB-N (from 16.32 mg N/100 g to 19.94 mg N/100 g), K-value (from 3.73% to 7.07%), and amino acid composition. The muscle structure change observed by Fourier-Transform Infrared spectroscopy (FT-IR) showed that the content of α-helix reduced from 59.05% to 51.83%, while the β-sheet fraction grew from 15.44% to 17.11%, β-turns increased from 5.45% to 7.58%, and random coil from 20.06% to 23.49%. Moreover, muscular structure exhibited varying degrees of deterioration with increasing cycles of freezing and thawing as shown by scanning electron microscopy (SEM). We studied the muscular morphology, which included the measurement of porosities (%) of pore that increased (from 1.4% to 4.3%) and pore distribution, by X-ray computed tomography (uCT). The cycles of the freeze–thaw resulted in structural changes, which seemed to be closely associated with ultimate quality of frozen fish products.
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Wilson, D. G. "The Supplementary-Fired Exhaust-Heated Cycle for Coal, Wood and Refuse-Derived Fuel". Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 207, nr 3 (sierpień 1993): 203–8. http://dx.doi.org/10.1243/pime_proc_1993_207_034_02.
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An analysis is presented of a system that would enable refuse-derived fuel (RDF) (produced from, principally, paper) or other biomass (for example wood chips) or coal to be burned cleanly in a highly efficient gas turbine system of a size that would match the needs of many communities (a solid waste flow of 1000–3000 tons per day). The system consists of a gas turbine engine with two principal and several minor additions. The principal additions are a combustor to burn the RDF at approximately atmospheric pressure in the hot turbine exhaust flow and a high-temperature heat exchanger to transfer heat from this stream to the compressed air leaving the compressor. A design-point thermal efficiency of 55–60 per cent and high off-design efficiencies are predicted for the most favourable configuration with components designed for the purpose. About half the heat input would come from the RDF and half from conventional gas turbine liquid or gas fuel. In this paper the possible alternative configurations of such a plant are discussed, the thermodynamic implications are reviewed and some typical component performance values are introduced so that the overall plant performance can be predicted.
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Muslimin, Muslimin, Grenny Sudarmawan, Zhazha Yoslin i Dhiya Luqyana. "Mechanical Properties Comparison Between Induction Hardening and Rehardening of <i>Axle Shaft</i> AISI 1043 According to JIS G 0559 Standard". Key Engineering Materials 948 (6.06.2023): 3–12. http://dx.doi.org/10.4028/p-muclo2.
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Induction hardening is carried out to increase the hardness of the axle shaft surface. Axle shaft specimens were hardened from the bearing seat area to the spline area of the axle. The hardness requirements of the scope of the shaft met 400-450 HV of the JIS G 0559 standard. The axle shaft's hardening process with induction coil stops in the field before reaching the spline area. It causes the hardness becomes uneven and not comply with the standard. The re-hardening process is often carried out to repair rejected parts. In this work, the result of the re-hardening process is analyzed and compared with the first hardening process—the analysis focus on mechanical properties such as static test (torque test), fatigue testing, and hardness. Microstructures were used to verify the result of the process. The results showed that the results of re-hardening can meet the expected qualifications. The difference in breaking torque (static test) values is 4,428.155 Nm for hardening specimens and 4,287.832 Nm for re-hardening with a standard torque of 4,000.000 Nm, all samples fractured in the spline area. High fatigue values were obtained from the hardening results, with 216,265 cycles and 252,224 cycles for re-hardening. The results of the re-hardening hardness test obtained from Vickers are higher than the hardening results. The results of microstructural testing in both hardening processes contained ferrite and Fe3C on the surface and for the core consisting of ferrite and pearlite. Based on the analysis, the re-hardening process has no significant effect compared with the hardening results. Therefore, in this case, the re-hardening process can be used to fix the failed part.
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Zdanowicz, Christian M., Bernadette C. Proemse, Ross Edwards, Wang Feiteng, Chad M. Hogan, Christophe Kinnard i David Fisher. "Historical black carbon deposition in the Canadian High Arctic: a <i>></i>250-year long ice-core record from Devon Island". Atmospheric Chemistry and Physics 18, nr 16 (27.08.2018): 12345–61. http://dx.doi.org/10.5194/acp-18-12345-2018.
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Abstract. Black carbon aerosol (BC), which is emitted from natural and anthropogenic sources (e.g., wildfires, coal burning), can contribute to magnify climate warming at high latitudes by darkening snow- and ice-covered surfaces, and subsequently lowering their albedo. Therefore, modeling the atmospheric transport and deposition of BC to the Arctic is important, and historical archives of BC accumulation in polar ice can help to validate such modeling efforts. Here we present a > 250-year ice-core record of refractory BC (rBC) deposition on Devon ice cap, Canada, spanning the years from 1735 to 1992. This is the first such record ever developed from the Canadian Arctic. The estimated mean deposition flux of rBC on Devon ice cap for 1963–1990 is 0.2 mg m−2 a−1, which is at the low end of estimates from Greenland ice cores obtained using the same analytical method ( ∼ 0.1–4 mg m−2 a−1). The Devon ice cap rBC record also differs from the Greenland records in that it shows only a modest increase in rBC deposition during the 20th century. In the Greenland records a pronounced rise in rBC is observed from the 1880s to the 1910s, which is largely attributed to midlatitude coal burning emissions. The deposition of contaminants such as sulfate and lead increased on Devon ice cap in the 20th century but no concomitant rise in rBC is recorded in the ice. Part of the difference with Greenland could be due to local factors such as melt–freeze cycles on Devon ice cap that may limit the detection sensitivity of rBC analyses in melt-impacted core samples, and wind scouring of winter snow at the coring site. Air back-trajectory analyses also suggest that Devon ice cap receives BC from more distant North American and Eurasian sources than Greenland, and aerosol mixing and removal during long-range transport over the Arctic Ocean likely masks some of the specific BC source–receptor relationships. Findings from this study suggest that there could be a large variability in BC aerosol deposition across the Arctic region arising from different transport patterns. This variability needs to be accounted for when estimating the large-scale albedo lowering effect of BC deposition on Arctic snow/ice.
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Durand, Yves. "Le nouveau cycle 3 implique-t-il un rapprochement entre l��cole �l�mentaire et le coll�ge�?" Administration & �ducation N�158, nr 2 (2018): 17. http://dx.doi.org/10.3917/admed.158.0017.
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Wang, Junfeng, Dantong Liu, Xinlei Ge, Yangzhou Wu, Fuzhen Shen, Mindong Chen, Jian Zhao i in. "Characterization of black carbon-containing fine particles in Beijing during wintertime". Atmospheric Chemistry and Physics 19, nr 1 (11.01.2019): 447–58. http://dx.doi.org/10.5194/acp-19-447-2019.
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Abstract. Refractory black carbon (BC) is a product of incomplete combustion of fossil fuel, biomass and biofuel, etc. By mixing with other species, BC can play significant roles in climate change, visibility impairment and human health. Such BC-containing particles in densely populated megacities like Beijing may have specific sources and properties that are important to haze formation and air quality. In this work, we exclusively characterized the BC-containing particles in urban Beijing by using a laser-only Aerodyne soot particle aerosol mass spectrometer (SP-AMS), as part of the Atmospheric Pollution & Human Health (APHH) 2016 winter campaign. The average mass ratio of coating to BC core (RBC) was found to be ∼5.0. Positive matrix factorization shows the presence of significant primary fossil fuel and biomass-burning organics (64 % of total organics). Yet secondary species, including sulfate, nitrate and oxygenated organic aerosol (OA) species, could have significant impacts on the properties of BC-containing particles, especially for ones with larger BC core sizes and thicker coatings. Analyses of sources and diurnal cycles of organic coating reveal significant afternoon photochemical production of secondary OA (SOA), as well as nighttime aqueous production of a portion of highly oxygenated OA. Besides SOA, photochemical production of nitrate, not sulfate, appeared to be important. Further investigations on BC-containing particles during different periods show that, on average, more polluted periods would have more contributions from secondary species and more thickly coated BC tended to associate with more secondary species, indicating the important role of chemical aging to the pollution of BC-containing particles in urban Beijing during wintertime. However, for individual pollution events, primary species (fossil fuel, coal and biomass-burning emissions) could also play a dominant role, as revealed by the compositions of BC-containing particles in two polluted episodes during the sampling period.
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Catuneanu, Octavian, i Arthur R. Sweet. "Maastrichtian-Paleocene foreland-basin stratigraphies, western Canada: a reciprocal sequence architecture". Canadian Journal of Earth Sciences 36, nr 5 (1.05.1999): 685–703. http://dx.doi.org/10.1139/e98-018.
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Palynological and magnetostratigraphic chronostratigraphic correlations of lower Maastrichtian to Paleocene strata along an east-west Western Canada Basin transect allow for the recognition of a reciprocal sequence architecture in nonmarine strata. Reference sections include three Canadian Continental Drilling Program Cretaceous-Tertiary Boundary Project core holes and outcrops in Alberta, southern Saskatchewan, and north-central Montana. The spatial and temporal position of the third-order sequences provides evidence for the correlation of proximal sector regional disconformities and sedimentary wedges with distal sector sedimentary wedges and regional disconformities, respectively. The boundary between the two sectors is represented by a hingeline, which separates the foreland-basin "syncline" from the "peripheral bulge." The stratigraphies defined by reciprocal third-order sequences are complicated by fourth-order boundaries, developed within proximal sedimentary wedges and with no correlative distal strata. These results support tectonic control on foreland-basin sedimentation. A model for interpreting the various types of sequences in terms of foreland-basin evolution, vertical tectonics, and orogenic cycles is provided. It is argued that nonmarine sequence boundaries (times of maximum uplift in the foreland region) may be expressed as disconformities, incised valleys, top of mature paleosol levels, or base of fluvial channels, whereas nonmarine equivalents of marine maximum flooding surfaces (times of maximum basinal subsidence) may be indicated by extensive coal seams and (or) lacustrine sediments.
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Li, Junjie, i Wanjing Cheng. "Comparative life cycle energy consumption, carbon emissions and economic costs of hydrogen production from coke oven gas and coal gasification". International Journal of Hydrogen Energy 45, nr 51 (październik 2020): 27979–93. http://dx.doi.org/10.1016/j.ijhydene.2020.07.079.
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Li, Jingying, Xiaoxun Ma, Heng Liu i Xiyu Zhang. "Life cycle assessment and economic analysis of methanol production from coke oven gas compared with coal and natural gas routes". Journal of Cleaner Production 185 (czerwiec 2018): 299–308. http://dx.doi.org/10.1016/j.jclepro.2018.02.100.
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