Journal articles on the topic 'Fossil sinters'
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Kieush, Lina, Maksym Yaholnyk, Maksym Boyko, Andrii Koveria, and Vladyslav Ihnatenko. "STUDY OF BIOMASS UTILISATION IN THE IRON ORE SINTERING." Acta Metallurgica Slovaca 25, no. 1 (June 4, 2021): 55–64. http://dx.doi.org/10.36547/ams.25.1.8.
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Dominating globally and within Ukraine, the blast-furnace practice for iron production requires iron ore sintering preparation wherein the significant amount of fossil fuel is consumed, accompanied by harmful emissions into the environment. Pursuing the purpose to mitigate this negative impact, we address the promising direction of biomass utilisation for a partial replacement of fossil fuels in iron ore sintering. This paper considers the benefits of fossil fuels substitution with biomass, the world practice of biomass utilisation in iron ore sintering and the scope of the biomass energy potential in Ukraine. The study for obtaining sinters with the use of raw biomass fuels (sunflower husk, walnut shell) and charcoal has been carried out via lab-scale sintering pot. The influence of various biomaterials types on the process of iron ore sintering have been investigated and the obtained sinter quality in comparison with the conventional types of the fuels allows establishing the feasibility of replacing 25 % of coke breeze by charcoal or by walnut shell. The sunflower husk application is possible if preliminary preparation of the material for increasing bulk density is assumed to be carried out, for instance, by pressing.
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Kieush, Lina, Maksym Yaholnyk, Maksym Boyko, Andrii Koveria, and Vladyslav Ihnatenko. "STUDY OF BIOMASS UTILISATION IN THE IRON ORE SINTERING." Acta Metallurgica Slovaca 25, no. 1 (June 23, 2019): 55. http://dx.doi.org/10.12776/ams.v1i1.1225.
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<p class="AMSmaintext">Dominating globally and within Ukraine, the blast-furnace practice for iron production requires iron ore sintering preparation wherein the significant amount of fossil fuel is consumed, accompanied by harmful emissions into the environment. Pursuing the purpose to mitigate this negative impact, we address the promising direction of biomass utilisation for a partial replacement of fossil fuels in iron ore sintering. This paper considers the benefits of fossil fuels substitution with biomass, the world practice of biomass utilisation in iron ore sintering and the scope of the biomass energy potential in Ukraine. The study for obtaining sinters with the use of raw biomass fuels (sunflower husk, walnut shell) and charcoal has been carried out via lab-scale sintering pot. The influence of various biomaterials types on the process of iron ore sintering have been investigated and the obtained sinter quality in comparison with the conventional types of the fuels allows establishing the feasibility of replacing 25 % of coke breeze by charcoal or by walnut shell. The sunflower husk application is possible if preliminary preparation of the material for increasing bulk density is assumed to be carried out, for instance, by pressing.</p>
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Trewin, Nigel H., Stephen R. Fayers, and Ruth Kelman. "Subaqueous silicification of the contents of small ponds in an Early Devonian hot-spring complex, Rhynie, Scotland." Canadian Journal of Earth Sciences 40, no. 11 (November 1, 2003): 1697–712. http://dx.doi.org/10.1139/e03-065.
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The Early Devonian Rhynie and Windyfield cherts of northeast Scotland originated as siliceous sinters deposited by hot springs. Silicification affected both subaerial and subaqueous environments, preserving a diverse terrestrial and freshwater biota. Cherts originally deposited in small shallow pools can be recognised on the basis of both texture and fossil content. Textures comprise clotted and microcoprolitic textures, bacterial coatings on plant axes that can be stromatolitic, and a variety of bacterial and fungal meshworks. The crustacean Lepidocaris, the euthycarcinoid Heterocrania, the charophyte alga Palaeonitella, and chytrid fungi are typical elements of the aquatic biota. Observations of modern hot springs in Yellowstone National Park, Wyoming, U.S.A., demonstrate that shallow ponds and streams on low-angle outwash areas and dormant vent orifices provide suitable environmental analogues. Textures comparable to those described from Rhynie are recorded from Yellowstone sinters, but examples of the rapid and complete silicification of delicate organic structures as seen in a few of the Rhynie chert beds have not been noted. Petrographic textures comparable to those seen in the cherts of freshwater origin from Rhynie occur in modern stream sinters at Yellowstone, where they form from waters at 2028 °C and with a pH of 8.7. This similarity occurs despite differences in environment at Yellowstone, such as the oxidizing surface environment, water table fluctuations, complex modern vegetation, fixing of silica by diatoms, and climatic extremes. Thus there are close similarities between textures seen in the Rhynie cherts and Yellowstone sinters deposited in freshwater pools and streams by hot springs.
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Finney, S. M., and L. I. Anderson. "A mechanical preparation of Rhynie Chert fossils." Geological Curator 9, no. 3 (September 2010): 207–11. http://dx.doi.org/10.55468/gc230.
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The Early Devonian Rhynie cherts represent the surface deposits of a subaerial hot spring system. Historically palaeobotanists have studied the exceptionally preserved early land plants contained within the cherts by mounting thin sections of the rock on glass microscope slides. Investigation of plant morphology and life habitat has relied on reconstruction from consecutive serial sections with the inherent loss of information at the blade width scale. Here we detail the previously unrealised potential for some of the Rhynie chert beds to respond well to mechanical preparation. Recognition that some chert beds may be prepared in this way provides an additional technique for the continued investigation of the flora and fauna of this important fossil locality. The technique might find wider application in the investigation of other more recently discovered fossil-bearing sinters worldwide.
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Camprubí, Antoni, Edith Fuentes-Guzmán, Pilar Ortega-Larrocea, María Colín-García, Janet Gabites, Luis F. Auqué, Vanessa Colás, and Eduardo González-Partida. "The Pliocene Ixtacamaxtitlán low sulfidation epithermal deposit (Puebla, Mexico): A case of fossil fungi consortia in a steam-heated environment." Boletín de la Sociedad Geológica Mexicana 72, no. 3 (November 28, 2020): A140420. http://dx.doi.org/10.18268/bsgm2020v72n3a140420.
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The Ixtacamaxtitlán area in northern Puebla (central Mexico) contains middle Miocene Cu-Mo-Au porphyry/skarn and Pliocene low-sulfidation Au-Ag epithermal deposits that are geologically associated with the evolution of the Trans-Mexican Volcanic Belt (TMVB). In this paper, a new 40Ar/39Ar age (2.87 ± 0.41 Ma) is provided for rhombohedral alunite from a kaolinite + alunite ± opal ± cristobalite ± smectite advanced argillic alteration assemblage. This age contributes to the definition of a metallogenic province that is confined to the TMVB, a relevant feature for regional exploration. A ~12 My gap is established between the formation of the Cu-Mo-Au porphyry/skarn and low-sulfidation Au-Ag epithermal deposits, which rules out the possibility that their overlapping was the result of telescoping. Advanced argillic alteration is conspicuous throughout the mineralized area. This alteration assemblage consists of a widespread kaolinite-rich blanket that underlies silica sinters, polymictic hydrothermal breccias, and an alunite-rich spongy layer that consists of vertical tubular structures that are interpreted as the result of gas venting in a subaerial environment. The above indicate a shallow hypogene origin for the advanced argillic alteration assemblage—that is, formation by the partial condensation within a phreatic paleoaquifer of acidic vapors that were boiled-off along fractures that host epithermal veins at depth. The formation of the spongy alunite layer and silica sinters is interpreted to have been synchronous. Within the alunite-rich spongy layer, tubular structures hosted microbial consortia dominated by fungi and possible prokaryote (Bacteria or Archaea) biofilms. Such consortia were developed on previously formed alunite and kaolinite and were preserved due to their replacement by opal, kaolinite, or alunite. This means that the proliferation of fungi and prokaryotes occurred during a lull in acidic gas venting during which other organisms (i.e., algae) might have also prospered. Periodic acidic gas venting is compatible with a multi-stage hydrothermal system with several boiling episodes, a feature typical of active geothermal systems and of low-sulfidation epithermal deposits. The microstructures, typical for fungi, are mycelia, hyphae with septa, anastomoses between branches, and cord-like groupings of hyphae. Possible evidence for skeletal remains of prokaryote biofilms is constituted by cobweb-like microstructures composed of <1 µm thick interwoven filaments in close association with hyphae (about 2.5 µm thick). Bioweathering of previously precipitated minerals is shown by penetrative biobrecciation due to extensive dissolution of kaolinite by mycelia and by dissolution grooves from hyphae on alunite surfaces. Such bioweathering was possibly predated by inorganically driven partial dissolution of alunite, which suggests a lull in acidic gas venting that allowed living organisms to thrive. This interpretation is sustained by the occurrence of geometrical dissolution pits in alunite covered by hyphae. Fungal bioweathering is particularly aggressive on kaolinite due to its relatively poor nutrient potential. Such delicate microstructures are not commonly preserved in the geological record. In addition, numerous chalcopyrite microcrystals or microaggregates are found within the alunite layer, which could be related to sulfate reduction due to bacterial activity from the sulfate previously released by fungal bioweathering of alunite. Hydrogeochemical modeling constrains pH to between ~3.2 and ~3.6 and temperature to between 53 and 75 °C during the stage in which fungi and other organisms thrived. These waters were cooler and more alkaline than in earlier and later stages, which were characterized dominantly by steam-heated waters. The most likely process to account for this interlude would be mixing with meteoric water or with upwelling mature water that did not undergo boiling.
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Labandeira, Conrad C., and Dena M. Smith. "Forging a future for fossil insects: thoughts on the First International Congress of Paleoentomology." Paleobiology 25, no. 2 (1999): 154–57. http://dx.doi.org/10.1017/s0094837300026476.
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Insects are the most diverse macroorganismic group to ever inhabit the planet, constituting a major share of the animal biomass in terrestrial and freshwater ecosystems. Since their first appearance in the fossil record some 400 million years ago, they have expanded ecologically into almost every niche except the ocean below the photic zone. When fossilized, their chitinous exoskeletons typically are well preserved, as evidenced by a respectable fossil record. They are found notably in lacustrine shales and amber but also occur in siderite nodules, lithographic limestone, sinter deposits, asphalt, and various glacial deposits. Insect fossils are major subjects in phylogenetic studies but are used to a lesser extent in understanding past ecological associations and reconstruction of ancient environments.
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Fanny, Widdy Andya, S. Subagjo, and Tirto Prakoso. "Pengembangan katalis Kalsium Oksida untuk sintesis biodiesel." Jurnal Teknik Kimia Indonesia 11, no. 2 (October 2, 2018): 66. http://dx.doi.org/10.5614/jtki.2012.11.2.1.
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The Improvement of Calcium Oxide Catalyst for Biodiesel Synthesis The development of industrial’s sector resulted in increasing demand for fuel. Fuel used is obtained from fossil fuel which is limited, and it produces several harmful gases to environment. To overcome these obstacles, the research on alternative energy resources has begun. Biodiesel has become more attractive because of its environmental benefits and it is made from renewable resources. Biodiesel is produced from vegetable oil by transesterification reaction. The aim of this research is development of CaO become super base CaO as heterogeneous for biodiesel synthesis by transesterification. The activities of both catalysts were tested by transesterification reaction in batch reactor at 60–65 oC for 4 hours. Both of those catalysts were characterized; include crystallinity by XRD, strength of base and surface area by BET method. Those solids have the basic strength about 10–11, crystalline structures, and the surface area of super base CaO about 7.7 m2/g and CaO about 9.6 m2/g. The content of methyl ester in biodiesel produced reaches 98.8%. According to SNI (minimal 96.5 %-wt) and ASTM, biodiesel of this reaction can be used as renewable energy source. Keywords: CaO, super base CaO, transesterification, biodiesel Abstrak Berkembangnya industri di dunia mengakibatkan meningkatnya kebutuhan akan bahan bakar. Selama ini bahan bakar yang digunakan diperoleh dari bahan bakar fosil yang jumlahnya terbatas, terlebih lagi hasil pembakaran bahan bakar fosil cenderung tidak ramah lingkungan. Untuk mengatasi berbagai kendala yang ditimbulkan dari penggunaan bahan bakar fosil, penelitian terhadap sumber energi alternatif mulai dilakukan. Biodiesel menarik perhatian dunia karena hasil pembakarannya lebih ramah lingkungan dan berasal dari sumber yang terbarukan. Biodiesel dihasilkan dari minyak nabati melalui reaksi transesterifikasi.Penelitian ini mengembangkan katalis CaO menjadi katalis CaO super basa untuk reaksi transesterifikasi pembentukan biodiesel. Aktivitas katalis CaO dan katalis CaO super basa tersebut diuji melalui reaksi transesterifikasi di dalam reaktor partaian pada suhu 60–65 oC selama 4 jam. Karakterisasi padatan meliputi uji kristalinitas dengan metode XRD, uji kekuatan basa, dan uji luas permukaan dengan metode BET. Hasil penelitian menunjukkan bahwa padatan memiliki kekuatan basa berkisar 10–11, bersifat kristalin, dan memiliki luas permukaan sebesar 7,7 m2/g untuk CaO super basa dan 9,6 m2/g untuk CaO. Kadar metil ester biodiesel yang dihasilkan mencapai 98,8%. Kadar metil ester menurut SNI (minimal 96,5 %-b) dan ASTM, biodiesel dari reaksi ini dapat digunakan sebagai sumber energi terbarukan. Kata Kunci: CaO, CaO super basa, transesterifikasi, biodiesel
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Liu, Chao, Yue Kang, Yuzhu Zhang, Hongwei Xing, and Guijun Xue. "Effect of Replacing Coke with Biomass Fuel on Sinter Properties and Pollutant Emissions." Metals 12, no. 9 (September 7, 2022): 1483. http://dx.doi.org/10.3390/met12091483.
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In the iron-ore-sintering process, the use of biomass charcoal instead of coke breeze can reduce the emission of flue gas pollutants and alleviate the energy crisis of fossil fuels. However, the direct application of biomass charcoal to iron ore sintering is bound to affect the sinter properties. The effects of biomass charcoal addition on the sintering ore properties and flue gas pollutants emission were studied through sintering cup and related performance test experiments. Meanwhile, the influence mechanism of biomass charcoal instead of coke breeze on iron ore sintering was expounded. The experimental results show that with an increase in biomass charcoal, the vertical sintering rate increased, the internal pore structure developed rapidly, and the pollutant emission decreased gradually. When the biomass charcoal content was less than 40%, the sinter strength and yield were stable and slightly improved with the increase in biomass charcoal. When the biomass charcoal content was higher than 40%, the metallurgical properties of sinter degraded sharply, making it difficult to meet the production requirements. The comprehensive effect of biomass charcoal on the sinter suggests that the suitable biomass charcoal addition was 40%; under this condition, the reduction in SO2 and NOx was 28.2% and 25.7%, respectively.
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Ghosh, Wriddhiman, Somnath Mallick, Prabir Kumar Haldar, Baishali Pal, Subhas Chandra Maikap, and Sujoy Kumar Das Gupta. "Molecular and Cellular Fossils of a Mat-Like Microbial Community in Geothermal Boratic Sinters." Geomicrobiology Journal 29, no. 10 (December 2012): 879–85. http://dx.doi.org/10.1080/01490451.2011.635761.
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Konhauser, Kurt O., Brian Jones, Anna-Louise Reysenbach, and Robin W. Renaut. "Hot spring sinters: keys to understanding Earth's earliest life forms." Canadian Journal of Earth Sciences 40, no. 11 (November 1, 2003): 1713–24. http://dx.doi.org/10.1139/e03-059.
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The question of what composed the Earth's oldest fossils is the subject of current debate. At present, taphonomical determination of Archean silicified microfossils is largely based on morphological comparisons with extant microorganisms. This method has significant shortcomings because little is known about which types of bacteria silicify, what physical changes are induced on those species during mineralization, and, most importantly, what their preservation potential is. Terrestrial hot springs may help resolve these uncertainties because the silica-supersaturated geothermal fluids mineralize a wide variety of natural microbial communities and thus lead to the formation of numerous distinct biofacies. Some of these biofacies are reminiscent of Archean siliceous stromatolites from which the oldest microfossils were recovered. We suggest that by integrating molecular techniques that characterize the indigenous microbial populations growing in different biofacies with electron microscopy, we may be able to assess better what types of ancient microbes could have become fossilized.
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Channing, Alan. "A review of active hot-spring analogues of Rhynie: environments, habitats and ecosystems." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1739 (December 18, 2017): 20160490. http://dx.doi.org/10.1098/rstb.2016.0490.
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The Lower Devonian Rhynie chert formed as silica sinter entombed an early terrestrial ecosystem. Silica sinter precipitates only from water flowing from alkali-chloride hot springs and geysers, the surface expression of crustal-scale geothermal systems that form low-sulfidation mineral deposits in the shallow subsurface. Active alkali-chloride hot springs at Yellowstone National Park create a suite of geothermally influenced environments; vent pools, sinter aprons, run-off streams, supra-apron terrace pools and geothermal wetlands that are habitats for modern hot-spring ecosystems. The plant-rich chert, which makes Rhynie internationally famous, probably formed in low-temperature environments at the margins of a sinter apron where frequent flooding by geothermal water and less frequent flooding by river waters created ephemeral to permanent wetland conditions. Here, the plants and associated microbes and animals would be immersed in waters with elevated temperature, brackish salinity, high pH and a cocktail of phytotoxic elements which created stresses that the fossil ecosystem must have tolerated. The environment excluded coeval mesophytic plants, creating a low-diversity hot-spring flora. Comparison with Yellowstone suggests the Rhynie plants were preadapted to their environment by life in more common and widespread environments with elevated salinity and pH such as coastal marshes, salt lakes, estuaries and saline seeps. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.
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Gan, Min, Wei Lv, Xiaohui Fan, Xuling Chen, Zhiyun Ji, and Tao Jiang. "Gasification Reaction Characteristics between Biochar and CO2 as well as the Influence on Sintering Process." Advances in Materials Science and Engineering 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/9404801.
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For achieving green production of iron ore sintering, it is significant to substitute biochar, which is a clean and renewable energy, for fossil fuels. In this paper, the gasification reaction between CO2 and biochar was investigated. The results showed the initial temperature and the final temperature of the gasification reaction between biochar and CO2 were lower, while the maximum weight loss rate and the biggest heat absorption value were much higher than those of coke breeze, which indicated gasification reaction between the biochar and CO2 occurred rapidly at lower temperature. The gasification activation energy of biochar was 131.10 kJ/mol, which was lower than that of the coke breeze by 56.26 kJ/mol. Therefore, biochar had a higher reactivity and easily reacted with CO2 to generate CO. As a result, when biochar replaced coke powder at equal heat condition in sintering process, the combustion efficiency of fuel decreased and was disadvantage to the mineralization of iron ores at high temperature. With the increase of substitute proportion, the sinter yield, tumble strength, and productivity were decreased. The proportion of biochar replacing coke breeze should not be higher than 40%. By reducing the heat replacement ratio of biochar, the yield and quality of sinter got improved.
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Preston, L. J., G. K. Benedix, M. J. Genge, and M. A. Sephton. "A multidisciplinary study of silica sinter deposits with applications to silica identification and detection of fossil life on Mars." Icarus 198, no. 2 (December 2008): 331–50. http://dx.doi.org/10.1016/j.icarus.2008.08.006.
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Pei, Martin, Markus Petäjäniemi, Andreas Regnell, and Olle Wijk. "Toward a Fossil Free Future with HYBRIT: Development of Iron and Steelmaking Technology in Sweden and Finland." Metals 10, no. 7 (July 18, 2020): 972. http://dx.doi.org/10.3390/met10070972.
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The Swedish and Finnish steel industry has a world-leading position in terms of efficient blast furnace operations with low CO2 emissions. This is a result of a successful development work carried out in the 1980s at LKAB (Luossavaara-Kiirunavaara Aktiebolag, mining company) and SSAB (steel company) followed by the closing of sinter plants and transition to 100% pellet operation at all of SSAB’s five blast furnaces. However, to further reduce CO2 emission in iron production, a new breakthrough technology is necessary. In 2016, SSAB teamed up with LKAB and Vattenfall AB (energy company) and launched a project aimed at investigating the feasibility of a hydrogen-based sponge iron production process with fossil-free electricity as the primary energy source: HYBRIT (Hydrogen Breakthrough Ironmaking Technology). A prefeasibility study was carried out in 2017, which concluded that the proposed process route is technically feasible and economically attractive for conditions in northern Sweden/Finland. A decision was made in February 2018 to build a pilot plant, and construction started in June 2018, with completion of the plant planned in summer 2020 followed by experimental campaigns the following years. Parallel with the pilot plant activities, a four-year research program was launched from the autumn of 2016 involving several research institutes and universities in Sweden to build knowledge and competence in several subject areas.
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Siddique, Amna, and Muhammad Anis-ur-Rehman. "Study of Structural and Electrical Properties of CuFe-CGN for Renewable Energy Applications." Nano Hybrids and Composites 37 (August 31, 2022): 33–39. http://dx.doi.org/10.4028/p-co85a8.
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Renewable energy source is a clean energy production source and can overcome climatic challenges caused by the excessive use of fossil fuels. The nanocrystalline material of composition Cu0.2Fe0.2(Ce0.6Gd0.4-xNdx)0.6O2-x has been synthesized by WOWS sol-gel process by varying Neodymium as such x= 0.0, 0.05. These samples were calcined at 500°C for 2 hours and the pellets were sintered at 750°C for 5 hours. X-Ray Diffraction technique confirms the cubic fluorite structure of the material. The doped material has showed high dielectric constant value and low dissipation factor and increased AC conductivity. AC conductivity obeys the Universal Dielectric Response. The material shows the potential for applications such as an electrode/electrolyte for fuel cells or also as a dielectric resonator.
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Tattersall, Ian. "Rethinking Human Evolution." PARADIGMI, no. 3 (December 2012): 11–25. http://dx.doi.org/10.3280/para2012-003002.
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La paleoantropologia č arrivata tardi alla Nuova Sintesi Evolutiva, ma quando ci č arrivata, si č arresa senza condizioni: al punto che ancora cinquant'anni dopo molti hanno avuto difficoltŕ ad adattarsi agli ultimi paradigmi del processo evolutivo. Si preferiscono ancora le interpretazioni minimaliste delle testimonianze fossili umane, e specie come l'Homo erectus vengono accorpate a rappresentare uno stadio "intermedio" nei modelli lineari dell'evoluzione umana, mentre un patrimonio di testimonianze di fossili umani rapidamente crescente denota una elevata diversitŕ tra le specie ominidi del passato. Un esame dello schema dell'evoluzione umana, in cui la stasi ha gran parte e le innovazioni comportamentali e anatomiche sono fuori fase, indica che la specie Homo sapiens non č il risultato di una sola linea che si sia andata modificando gradualmente. Č invece un ultimo ramo d'un lussureggiante cespuglio, e le sue incomparabili qualitŕ cognitive si spiegano meglio con un concorso di esattamento ed emergenza piuttosto che come semplice estrapolazione delle tendenze che l'hanno preceduta.
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Saputri, Dini Deviana, and Teguh Endah Saraswati. "Sintesis Carbon Nanotubes (CNT) Berbasis Bahan Alam Limbah Tempurung Kelapa dan Aplikasinya dalam Pembuatan Polimer Komposit Polimida-CNT: Review." Proceeding of Chemistry Conferences 6 (September 15, 2021): 38. http://dx.doi.org/10.20961/pcc.6.0.55088.38-46.
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<p><em>Carbon nanotubes</em> (CNT) menjadi salah satu material unggul teknologi nano yang membawa banyak keuntungan karena memiliki sifat kimia dan mekanik yang baik. Hal ini menjadikan CNT dimanfaatkan di berbagai aplikasi <em>nano-device </em>ataupun material komposit. Beberapa metode yang sering digunakan untuk menumbuhkan CNT adalah deposisi uap kimia (<em>Chemical Vapor Deposition</em>), laser ablasi dan <em>arc discharge</em>. Kebanyakan sumber prekursor karbon dalam sintesis CNT diambil dari bahan bakar fosil yang memiliki kelemahan bahan tidak bisa diperbaharui dan menghabiskan biaya yang mahal. Limbah bahan alam atau hasil biomassa dapat menjadi alternatif bahan baku pembuatan CNT yang membawa keunggulan biaya murah, ketersediaan melimpah, dan hemat energi, contohnya seperti limbah tempurung kelapa yang mengandung unsur karbon tinggi. Tempurung kelapa telah dilaporkan sebagai salah satu bahan baku potensial produksi CNT. Aplikasi CNT dalam polimer komposit contohnya penggabungan dengan polimida. Keunggulan polimida adalah sifat mekaniknya yang sangat baik, stabilitas termal, dan ketahanan kimia. Namun, polimida memiliki kelemahan dalam konduktivitas termal yang rendah. Penambahan CNT ke dalam polimida dapat meningkatkan konduktivitas termal sehingga meningkatkan kinerja polimer tersebut. </p><p><strong>Synthesis of Coconut-Shell Waste-based Carbon nanotubes (CNT) and Its Application in Polymer Composite Polyimide-CNT Fabrication: Review. </strong><em>Carbon nanotubes (CNTs) have become one of the excellent materials for nanotechnology which brings many advantages because of their good chemical and mechanical properties, inducing CNTs to be used in various nano-device applications or composite materials. Some of the methods commonly used to grow CNTs are chemical vapor deposition, laser ablation, and arc discharge. Most sources of carbon precursors in CNTs synthesis are taken from fossil fuels which have the disadvantages of non-renewable materials and high cost. Natural waste or biomass products can be an alternative raw material for CNTs production which brings the advantages of low cost, abundant availability, and energy-saving, for example, such as coconut shell waste which contains high carbon elements. Coconut shell has been reported as one of the potential raw materials for CNT production. CNT applications in composite polymers are for example collaboration with polyimides. The advantages of polyimides are their excellent mechanical properties and chemical resistance. However, polyimides have a disadvantage in their low thermal conductivity. The addition of CNT into polyimides can increase its thermal conductivity enhancing polyimide performance.</em></p><p align="center"> </p>
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Fibonacci, Anita. "Sintesis Alkohol Dari Limbah Nangka (Artocarpus heterophyllus) sebagai Campuran Bahan Bakar Minyak (Biofuel)." Walisongo Journal of Chemistry 2, no. 1 (June 13, 2019): 17. http://dx.doi.org/10.21580/wjc.v2i1.4043.
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Peningkatan akan kebutuhan energi terus meningkat seiring berjalannya waktu, namun peningkatan kebutuhan energy yang terjadi menimbulkan dampak semakin menipisnya pasokan ketersediaan bahan bakar fosil yang notabene merupakan sumber daya alam yang tak terbarui, disisi lain banyak limbah buah nangka (Artocarpus heterophyllus) yang sebenarnya berpotensi untuk diolah sebagai biofuel. Penelitian ini bertujuan untuk menghasilkan alkohol dari limbah nangka (Artocarpus heterophyllus) melalui proses fermentasi menggunakan saccharomyces cereviseae. Limbah buah nangka dimanfaatkan sebagai campuran bahan bakar minyak berbasis bahan dari biomassa (biofuel). Proses pembuatan alcohol dari limbah buah nangka diawali dengan pembuatan starter, medium fermentasi, proses fermentasi hingga mendapatkan alkohol dilanjutkan dengan proses pemurnian dengan cara destilasi. Analisis kadar alkohol dilakukan dengan metode berat jenis. Hasil penelitian menunjukkan bahwa alkohol yang dihasilkan dari limbah buah nangka (Artocarpus heterophyllus) adalah 20 % dengan waktu fermentasi 12 hari.
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Fayers, Stephen R., and Nigel H. Trewin. "A review of the palaeoenvironments and biota of the Windyfield chert." Transactions of the Royal Society of Edinburgh: Earth Sciences 94, no. 4 (December 2003): 325–39. http://dx.doi.org/10.1017/s0263593300000729.
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ABSTRACTThe Windyfield chert site is located 700 m NE of the original Rhynie chert locality at Rhynie, Aberdeenshire, Scotland. Originally identified by concentrations of surface float material, a drilling and trenching programme of the area in 1997 revealed a chert ‘pod’ in situ interbedded with fluvial/lacustrine sandstones and hydrothermally altered shales. Chert morphologies identified from float blocks and trench material range from tabular beds to lenticular pods displaying massive, nodular, laminated and brecciated fabrics, and geyserite splash textures. A suite of floral and faunal associations, when combined with distinctive macro- and microscopic chert textures, has been used to interpret depositional conditions. Palaeoenvironments ranged from terrestrial laminated, brecciated and vegetated sinter sheets to low-temperature pools and marginal aquatic settings. The flora comprises six higher land plant species, nematophytes, charophytes, various fungi and probable cyanobacteria. Arthropods include branchiopod crustaceans, a euthycarcinoid, trigonotarbid arachnids, centipedes, eoarthropleurids and a possible hexapod. The biota of the Windyfield chert is closely comparable to that found in the Rhynie chert. Together, the Windyfield and Rhynie cherts contain the most diverse associated fossil arthropod fauna of terrestrial and freshwater origin from rocks of comparable age anywhere in the world.
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Malihah, Lola. "Tantangan Dalam Upaya Mengatasi Dampak Perubahan Iklim Dan Mendukung Pembangunan Ekonomi Berkelanjutan: Sebuah Tinjauan." Jurnal Kebijakan Pembangunan 17, no. 2 (December 21, 2022): 219–32. http://dx.doi.org/10.47441/jkp.v17i2.272.
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The issue of climate change and global warming has now become a concern for all countries worldwide. Tackling climate change and sustainable development is part of the Sustainable Development Goals (SDGs). This article review aims to examine the various challenges in efforts to overcome climate change and support sustainable development. Several references obtained data that most countries in the world have indeed felt the impact of climate change and global warming. Various efforts and policies are carried out with these conditions to overcome the effect. Starting from applying the concept of circular economy, which is an anti-synthesis of linear economic activities, reducing the use of fossil fuels to carbon tax policies. But all these policies must also be understood and supported by all parties. Not only the government but all the private sector elements, entrepreneurs, and society. Awareness and participation of all parties are needed so that the impacts of climate change can be overcome and sustainable development can be implemented. This effort is not only for the current generation but also for the next generation.
Isu perubahan iklim dan pemanasan global saat ini memang telah menjadi kekhawatiran seluruh negara didunia. Penanganan perubahan iklim dan pembangunan berkelanjutan merupakan bagian dari tujuan Sustainable Development Goals (SDGs). Tulisan ini merupakan sebuah tinjauan yang mengkaji berbagai macam tantangan dalam upaya mengatasi perubahan iklim dan mendukung pembangunan berkelanjutan. Dari beberapa referensi yang menjadi acuan diperoleh data bahwa sebagian besar negara telah merasakan dampak dari perubahan iklim dan pemanasan global. Dengan kondisi tersebut dilakukan berbagai upaya dan kebijakan untuk mengatasi dampak yang ditimbulkan. Mulai dari penerapan konsep ekonomi sirkular yang dianggap sebagai anti sintesis dari kegiatan ekonomi linier, mengurangi pemakaian bahan bakar fosil sampai kebijakan pajak karbon. Namun semua kebijakan tersebut tentunya juga harus dipahami dan didukung oleh semua pihak. Bukan hanya pemerintah saja tetapi harus melibatkan semua unsur disektor swasta, pengusaha dan juga masyarakat. Diperlukan adanya kesadaran dan partisipasi semua pihak agar dampak perubahan iklim dapat diatasi dan pembangunan berkelanjutan dapat dilaksanakan. Upaya ini bukan hanya untuk generasi sekarang saja tetapi untuk generasi yang akan datang.
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Rastini, Endah Kusuma. "PEMBUATAN SERBUK KARBON AKTIF DARI LIMBAH BAMBU SEBAGAI PENYANGGA KATALIS LOGAM DALAM SINTESIS BIOFUEL SECARA FISCHER-TROPSCH." Indonesian Chemistry and Application Journal 2, no. 1 (August 28, 2018): 19. http://dx.doi.org/10.26740/icaj.v2n1.p19-25.
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Sintesis Fischer-Tropsch merupakan rute alternatif untuk konversi biomassa menjadi bahan bakar cair yang cukup menjanjikan karena produk biofuel yang dihasilkan memiliki karakteristik identik dengan bahan bakar fosil. Biomassa dikonversi menjadi gas sintesis (CO dan H2) melalui polimerisasi menjadi hidrokarbon rantai panjang (wax) dan selanjutnya dipotong-potong melalui proses perengkahan menghasilkan hidrokarbon rantai pendek (C5-C12) yang merupakan biofuel. Penggunaan karbon aktif sebagai penyangga dapat menghasilkan biofuel secara langsung. Penelitian ini bertujuan karakterisasi serbuk karbon aktif sebagai penyangga katalis logam yang akan digunakan dalam sintesis Fischer-Tropsch dan memanfaatkan limbah bambu sebagai sumber karbon aktif. Pembuatan karbon aktif dari bambu ini dilakukan dengan kombinasi aktivasi Karbonisasi-H3PO4 (A), Karbonisasi-H3PO4-Steam (B). Bambu dikecilkan ukurannya, dikeringkan dan diarangkan pada 5000C dengan aliran gas nitrogen dalam reaktor karbonisasi, diserbukkan, selanjutnya diaktivasi dengan H3PO4 85% dan dicuci sampai pH netral. Setelah pengeringan, sampel difungsionalisasi dengan HNO3 65%, dinetralkan, dikeringkan dan dikalsinasi pada 7000C. Struktur kristal pada karbon aktif dianalisa menggunakan XRD. Karbon aktif hasil berbagai urutan aktivasi memiliki profil XRD yang identik dan sudah menunjukkan spektra khas untuk karbon aktif. Karbon aktif yang dihasilkan sudah sesuai dengan struktur kristal berdasarkan sudut difraksi hasil analisis XRD. Aktivasi karbon yang diawali dengan steam kemudian ditreatment dengan asam fosfat (B) menunjukkan hasil yang lebih baik dalam hal terbentuknya gugus fungsi oksigen. Spektra gugus fungsi alkohol, fenol, karbonil, karboksilat muncul dengan intensitas yang cukup besar dibandingkan perlakuan aktivasi tanpa menggunakan steam. Hal ini menunjukkan bahwa kombinasi aktivasi fisik (steam) dan aktivasi kimia (asam fosfat) meningkatkan terbentuknya gugus fungsi oksigen dibandingkan proses fungsionalisasi menggunakan asam nitrat saja.
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Backes, Jana Gerta, Julian Suer, Nils Pauliks, Sabrina Neugebauer, and Marzia Traverso. "Life Cycle Assessment of an Integrated Steel Mill Using Primary Manufacturing Data: Actual Environmental Profile." Sustainability 13, no. 6 (March 19, 2021): 3443. http://dx.doi.org/10.3390/su13063443.
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The current dependency on steel within modern society causes major environmental pollution, a result of the product’s life cycle phases. Unfortunately, very little data regarding single steel production processes have been found in literature. Therefore, a detailed analysis of impacts categorized in terms of relevance cannot be conducted. In this study, a complete life cycle assessment of steel production in an integrated German steel plant of thyssenkrupp Steel Europe AG, including an assessment of emissions from the blast furnace, the basic oxygen furnace, and casting rolling, is carried out. The functional unit is set to 1 kg hot-rolled coil, and the system boundaries are defined as cradle-to-gate. This study models the individual process steps and the resulting emitters using the software GaBi. Total emissions could be distributed into direct, upstream, and by-product emissions, where the biggest impacts in terms of direct emissions from single processes are from the power plant (48% global warming potential (GWP)), the blast furnace (22% GWP), and the sinter plant (79% photochemical ozone creation potential (POCP)). The summarized upstream processes have the largest share in the impact categories acidification potential (AP; 69%) and abiotic depletion potential fossil (ADPf; 110%). The results, including data verification, furthermore show the future significance of the supply chain in the necessary reduction that could be achieved.
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Shang, Haixin, Changlian Chen, Yuan Jiang, and Shi Chen. "Preparation of Al and Sm Co-doped Apatite-Type Lanthanum Silicate Electrolyte and analysis of the conductivity mechanism." Journal of Physics: Conference Series 2351, no. 1 (October 1, 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2351/1/012014.
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The contradiction between the increasing demand for energy and the scarcity of traditional fossil energy sources is becoming increasingly acute, and it is urgent to accelerate the development and use of new, more efficient, and environmentally friendly energy sources. Apatite-type lanthanum silicate solid oxide electrolyte materials (La9.33Si6O26, LSO) are widely used in the field of fuel cell electrolytes due to their high ionic conductivity and high density. In this paper, Al and Sm co-doped LSO solid electrolytes were successfully prepared by the urea-nitrate combustion method. SEM images, relative density, and linear shrinkage of Al and Sm co-doped lanthanum silicate electrolytes sintered at different temperatures were compared. The results show that the best sintering temperature is 1500°C. The electrical conductivity of La9.33SmxSi5.5Al0.5O25.75+1.5x was analyzed by EIS. The conductivity of La9.33Sm0.2Si5.5Al0.5O26.05 is 2.56 × 10−4 S·cm−1 when measured at 600°C. The reason Al and Sm co-doping enhances the conductance is that Al doping generates oxygen vacancies and increases the interstitial oxygen (Oi) concentration. Doping of Sm not only increases the concentration of Oi but also reduces the concentration of cation vacancies, thus improving the conductivity of the electrolyte.
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Kusnanto. "PERAN KEAHLIAN TEKNOLOGI PROSES DAN SINTESIS BAHAN DALAM MENDUKUNG INDUSTRI NUKLIR DI INDONESIA." Jurnal Forum Nuklir 3, no. 1 (June 27, 2013): 1. http://dx.doi.org/10.17146/jfn.2009.3.1.289.
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Energi telah menjadi basic need, yang setara dengan kebutuhan pangan. Dengan pandangan jauh ke depan, kini sudah tiba saatnya untuk mengupayakan pengurangan ketergantungan pada sumber energi primer fosil dan dengan serius mengembangkan sumber energi primer baru yaitu energi nuklir, sinergi dengan pengembangan energi baru dan terbarukan yang lain. Pengembangan reaktor maju menjadi mutlak diperlukan bila energi nuklir akan tetap digunakan sebagai andalan teknologi pemenuhan energi. Peluang untuk mengembangkan industri proses bahan semakin terbuka di Indonesia. Kekayaan alam, mineral dan energi merupakan modal besar bila ditopang dengan kemampuan penguasaan teknologi dan kebijakan pemerintah yang berpihak pada kemampuan dan kemandirian bangsa. Bila hydrogen diproduksi menggunakan reaktor maju dapat diproduksi secara komersial, dapat dipastikan kebutuhan zircon oxide, yang merupakan produk antara industri zirconium logam, akan sangat tajam meningkat kebutuhannya, yaitu untuk fuel cell. Fuel cell jenis SOFC diyakini paling efisien untuk digunakan sebagai alat konversi energi yang menggunakan bahan bakar hydrogen. Agar kemandirian bangsa ini dapat terwujud, dibutuhkan sumber daya manusia yang memiliki keahlian teknologi proses. Keahlian tidak dapat diperoleh hanya melalui pendidikan formal di perguruan tinggi. Keahlian diperoleh melalui 3 tahapan yaitu: a) Pendidikan; b) Pelatihan c) Pengalaman kerja. Pelatihan dan pengalaman kerja memiliki kontribusi besar terhadap keahlian seseorang. Oleh karena itu sertifikasi keahlian/profesi yang terdiri atas aspek pelatihan atau pengalaman kerja menjadi hal-hal yang diperlukan untuk memenuhi kebutuhan di atas.
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Pallarès, Enric Lujan, Antonio Hinojo, Sergi Colominas, and Jordi Abella. "(Digital Presentation) Electrochemical Sensors for Hydrogen/Deuterium Speciation." ECS Meeting Abstracts MA2022-01, no. 54 (July 7, 2022): 2481. http://dx.doi.org/10.1149/ma2022-01542481mtgabs.
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By the end of the century, global energy demand is expected to increase by a factor of three due to population growth. In this context, fossil fuels should not be the main power source due to the elevated environmental cost. Nuclear fusion technology is planned as an alternative to this demand as it is expected to generate large quantities of energy without all the inconveniences of fossil fuels. The most feasible reaction to take place is the fusion between two hydrogen nuclei. Specifically, deuterium and tritium will react releasing helium, neutrons, and large amounts of energy [1]. 2H + 3H → 4He + n + 17.59 MeV (1) In the present work, BaCe0.6Zr0.3Y0.1O3-α electrolyte (BCZY) was used to construct amperometric sensors for hydrogen monitoring. Firstly, BCZY powder was synthesized by the solid-state method and characterized using SEM and XRD. Secondly, it was sintered as a pellet and bound to an alumina tube to construct the electrochemical sensors. Finally, amperometric measurements were performed inside a stainless-steel reactor at 500 °C and applying 0.15 V between electrodes. The response of the sensors was evaluated using hydrogen and deuterium calibration mixtures. The concentration in the WE ranged from 150 to 300 ppm H2 or D2 in Ar. Argon was used in the CE as a cover gas. Finally, measurements with hydrogen and deuterium were compared to determine the isotope effect on the response. [1] J.Kenneth. Shultis, R.E. Faw, Fundamentals of nuclear science and engineering, Marcel Dekker, 2002. [2] E.C.C. de Souza, R. Muccillo, Properties and applications of perovskite proton conductors, Materials Research. 13 (2010) 385–394. https://doi.org/10.1590/S1516-14392010000300018. [3] A. Benes, A. Molinari, R. Witte, R. Kruk, J. Brötz, R. Chellali, H. Hahn, O. Clemens, Proton Conduction in Grain-Boundary-Free Oxygen-Deficient BaFeO2.5+δ Thin Films, Materials. 11 (2017) 52. https://doi.org/10.3390/ma11010052. [4] A. Hinojo, I. Soriano, J. Abellà, S. Colominas, Evaluation of High-Temperature Hydrogen Sensors Based on BaCe0.6Zr0.3Y0.1O3-α and Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α Perovskites for Industrial Applications, Sensors. 20 (2020) 7258. https://doi.org/10.3390/s20247258.
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Johansson, Marcus, Tobias Mattisson, and Anders Lyngfelt. "Comparison of oxygen carriers for chemical-looping combustion." Thermal Science 10, no. 3 (2006): 93–107. http://dx.doi.org/10.2298/tsci0603093j.
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Chemical-looping combustion is a combustion technology with inherent separation of the greenhouse gas CO2. This technique involves combustion of fossil fuels by means of an oxygen carrier which transfers oxygen from the air to the fuel. In this manner a decrease in efficiency is avoided for the energy demanding separation of CO2 from the rest of the flue gases. Results from fifty oxygen carriers based on iron-, manganese- and nickel oxides on different inert materials are compared. The particles were prepared using freeze granulation, sintered at different temperatures and sieved to a size 125-180 mm. To simulate the environment the particles would be exposed to in a chemical-looping combustor, reactivity tests under alternating oxidizing and reducing conditions were performed in a laboratory fluidized bed-reactor of quartz. Reduction was performed in 50% CH4/50% H2O while the oxidation was carried out in 5% O2 in nitrogen. In general nickel particles are the most reactive, followed by manganese. Iron particles are harder but have a lower reactivity. An increase in sintering temperatures normally leads to an increase in strength and decrease in reactivity. Several particles investigated display a combination of high reactivity and strength as well as good fluidization behavior, and are feasible for use as oxygen carriers in chemical-looping combustion.
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Elystia, Shinta, Dian Larasati, and Sri Rezeki Muria. "Produksi Lipid dari Mikroalga Scenedesmus sp. Pada Media Limbah Cair Tahu dengan Variasi Konsentrasi Limbah dan Photoperiod." Al-Ard: Jurnal Teknik Lingkungan 5, no. 2 (May 1, 2020): 54–61. http://dx.doi.org/10.29080/alard.v5i2.519.
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Kebutuhan energi di berbagai negara lebih banyak dipenuhi dari bahan bakar fosil dan mengalami peningkatan setiap tahunnya sementara cadangan minyak bumi hanya cukup untuk 18 tahun ke depan. Berbagai penelitian telah dilakukan untuk memanfaatkan mikroalga sebagai bahan baku biodiesel. Scenedesmus sp. memiliki tingkat pertumbuhan dan produksi lipid yang tinggi dan memiliki asam lemak yang memadai untuk sintesis biodiesel serta dapat memanfaatkan bahan organik sebagai nutrisi berupa limbah cair tahu sehingga sinergi antara pengolahan limbah cair dan produksi biomassa dapat berjalan dengan baik.. Pada penelitian ini akan diteliti potensi mikroalga Scenedesmus sp. dengan variasi pemberian limbah cair tahu dalam medium kultivasi (0%, 20%, 40%, 60%, 80%, 100%) dengan perbandingan fotoperiod terang:gelap (16:8, 14:10, 12:12, dan 24:0) dan waktu pengambilan data pada hari ke-0, 1, 3, 5, 7, 9, 11, dan 13. Berdasarkan hasil penelitian diperoleh kadar lipid tertinggi sebesar 27,12% pada pemberian limbah cair tahu 20% dan fotoperiod 12:12 dengan efisiensi penyisihan COD sebesar 73,91%.
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Haryono, Haryono, Iman Rahayu, and Yati B. Yulyati. "Biodiesel dari Minyak Goreng Sawit Bekas dengan Katalis Heterogen CaO: Studi Penentuan Rasio Mol Minyak/Metanol dan Waktu Reaksi Optimum." Eksergi 13, no. 1 (June 1, 2016): 1. http://dx.doi.org/10.31315/e.v13i1.1413.
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Keterbatasan daya dukung bahan bakar fosil terhadap pemenuhan kebutuhan energi yang berkelanjutan dan ramah lingkungan, telah mengarahkan masyarakat pada upaya-upaya untuk menemukan dan mengembangkan sumber-sumber energi alternatif yang bersifat baru dan terbarukan. Salah satunya jenis energi terbarukan tersebut adalah biodiesel. Penelitian ini bertujuan untuk mensintesis biodiesel dengan memanfaatkan limbah minyak goreng sawit bekas. Penelitian dikhususkan pada penentuan rasio mol minyak/metanol dan waktu reaksi transesterifikasi dengan katalis basa heterogen CaO. Rasio mol minyak/metanol dipelajari pada variasi 1/5, 1/10, 1/15, dan 1/20. Sedangkan waktu reaksi divariasikan selama 1, 1,5, 2, 2,5, dan 3 jam. Reaksi dilakukan pada suhu 65oC dan kadar katalis CaO sebanyak 3%. Hasil penelitian menunjukkan bahwa kondisi optimum reaksi dicapai pada saat sintesis biodiesel dilakukan pada rasio mol minyak/metanol sebesar 1/15 dengan lama reaksi 2,5 jam. Pada kondisi reaksi tersebut diperoleh biodiesel dengan beberapa parameter kualitas yang diuji telah sesuai dengan SNI untuk Biodiesel (SNI-04-7182-2006), yaitu: densitas 0,867 g/cm3, viskositas 5,28 mm2/s (pada suhu 40oC), titik kilat 182oC, angka asam 0,28 mg KOH/g, gliserol bebas 0,014%, gliserol total 0,10%, kadar ester 97,8%, dan angka iod 31,62%, serta yield biodiesel sebesar 86,0%.
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Rachma, N., and Ahmad Syaekhul Umam. "Pertanian Organik Sebagai Solusi Pertanian Berkelanjutan Di Era New Normal." Jurnal Pembelajaran Pemberdayaan Masyarakat (JP2M) 1, no. 4 (January 23, 2021): 328. http://dx.doi.org/10.33474/jp2m.v1i4.8716.
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Keprihatinan petani terhadap lingkungan dan petani bekerja dengan bahan kimia pertanian dalam sistem pertanian konvensional yang mana bahan kimia pertanian membutuhkan proses pembuatan energi intensif yang sangat bergantung pada bahan bakar fosil, maka diperlukan merubah sistem pola pertanian yaitu dengan pertanian organik. Pertanian organik adalah sistem budidaya pertanian yang mengadalkan bahan-bahan alami tanpa menggunakan bahan kimia sintetis. Untuk menyukseskan sosialisasi pertanian organik di desa Dowan kecamatan Gunem kabupaten Rembang, Maka mahasiswa KKN-PPM edisi covid-19 kelompok 08 Universitas Islam Malang melakukan sosialisasi dengan cara Door to door. Pertanian organik memberikan dampak dalam pertanian berkelanjutan yang ada di Desa Dowan, baik dampak positif maupun dampak negatif. KKN Tematik Edisi Covid 19 Universitas Islam Malang Kelompok 8 melakukan suatu analisis untuk menjawab tantangan yang selama ini di alami oleh petani. KKN Tematik Edisi Covid 19 Universitas Islam Malang Kelompok 8 melakukan kegiatan sosialisasi untuk menuju pertanian organik dan menjadikan pertanian yang berkelanjutan serta memberikan pelatihan pembuatan pestisida organik sehingga nantinya menjadikan pertanian yang mandiri. Pertanian organik bertujuan untuk mengetahui prinsip dari pertanian organik, mengetahui kelebihan dari pertanian organik dan menyediakan produk-produk pertanian yang aman dikonsumsi dan tidak menimbulkan pencemaran lingkungan. Wawancara digunakan sebagai teknik pengumpulan data untuk menemukan permasalahan dan mengetahui keluhan dari petani yang lebih mendalam. KKN Tematik Edisi Covid 19 Universitas Islam Malang Kelompok 8 melakukan sosialisasi dengan memberikan pengetahuan tentang prinsip pertanian, mensosialisasikan tentang manfaat dari pertanian organik mensosialisasikan dan membantu petani untuk menciptakan produk pestisida organik untuk menuju pertanian berkelanjutan dan edukasi tentang rotasi tanaman sebagai satu penerapan sistem pertanian berkelanjutan.
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Pidburtnyi, Mykhailo, Haris Masood Ansari, and Viola Ingrid Birss. "Detailed Mechanistic Studies of Electrochemical Reactions on Pt and Au Electrodes in Solid Oxide Cells Via EIS Data Analysis." ECS Meeting Abstracts MA2022-01, no. 49 (July 7, 2022): 2072. http://dx.doi.org/10.1149/ma2022-01492072mtgabs.
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In order to reduce the environmental impact of fossil fuels, a range of sustainable technologies for power generation and storage are currently being developed. In addition, efficient and low-cost methods for CO2 capture and conversion to form useful products are critically needed. One of the promising technologies towards achieving these goals involves the use of solid oxide cells (SOC), which are unique devices that can be employed in both the fuel cell mode for clean power generation and in the electrolysis mode to achieve CO2 conversion through its electrochemical reduction (‘CO2RR’). One of the burning problems that is impeding SOC implementation is catalyst selection, with many promising materials having been reported over the last 50 years, including metals and mixed ionic and electronic conducting (MIEC) metal oxide materials. However, the reasons for better or worse activity, as well as the mechanism of the CO2RR at these catalysts remains unknown and it is often unclear what factors limit the catalyst activity during cell operation and how this can be improved. This is due, in part, to the limited number of techniques that can be used to evaluate these performance metrics, especially at high operating temperatures. One of the most useful techniques is electrochemical impedance spectroscopy (EIS). However, data interpretation is often quite complex and thus other methods, such as CNLS fitting or the determination of the distribution of relaxation times (DRT), are needed. While CNLS fitting allows the fit parameters to be correlated with specific physical properties, a precise model of the system is required. Since SOC systems are relatively unexplored and good models are not yet available, this could lead to the mis-interpretation of the EIS data. DRT, on the other hand, can be a useful tool since it does not require any pre-existing models of the system. Unlike CNLS fitting, DRT can provide the correct number of time constants present (from the number of peaks obtained), as well as the associated resistance and capacitance values. According to the literature, each peak is typically related to a specific reaction step with a unique capacitance value, identified by changing conditions such as temperature, polarization or gas composition. In the present work, DRT analysis of Pt and Au electrodes on YSZ electrolytes was carried out in order to determine the origin of each resistance and to determine the effect of temperature, electrode polarization and gas composition on both the resistance and capacitance values. Here, both porous and point metal electrodes were investigated as no double phase boundary activity or chemical capacitance effects should be present, making data interpretation less complex. Furthermore, to avoid the challenges of porous electrodes, point electrodes, produced by pressing the metal wire to a flat YSZ surface by applying pressure with a spring, followed by softening at 1100 °C to achieve better contact, were used to achieve a controllable triple phase boundary (TPB) length. This allowed the true activity of the metal/YSZ TPB to be measured as a function of reactive interface length, rather than just per geometric surface area. Porous electrodes were also studied, made by depositing Pt or Au paste onto YSZ, followed by sintering at 600 °C for 20 min. Polymeric YSZ precursors were then infiltrated into the metallic backbone, then sintered at 750 °C for 2 hours. Then, a thin layer of the same metal paste was applied in order to provide better conductivity. The point electrodes were made by attaching 0.3 mm thick Pt and Au wires onto dense and flat YSZ electrolyte by a spring-loaded cell holder, then held at 1050 °C for 1 hour to soften and produce a fixed TPB length. Electrochemical testing of the porous electrodes was conducted at 750 °C in both half- full cell modes in air, CO2 and CO2/CO mixtures, while the wires were tested at 650-750°C in the same gases, but in half-cell mode. 8 individual process were seen for both the porous and point electrodes, including both electrodes in each cell. The time constant with the smaller capacitors are likely related to the electrode-electrolyte interface, while the mid-range capacitors are associated with electrode surface processes, such as surface diffusion, molecular species dissociation, and adsorption. The high capacitance steps are likely related to gas-phase processes, such as gas diffusion and the possible presence of a conversion layer. More detailed analysis of polarization and gas atmosphere dependence is ongoing in order to confirm the nature of each process.
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Lesbani, Aldes, Risfidian Mohadi, and Eliza Eliza. "Sintesis Tris(4-metoksifenil)tolilsilan dengan Teknik Reaksi Kopling Menggunakan Katalis Paladium Tersier Tributil Fosfin." Jurnal Kimia VALENSI 3, no. 1 (May 27, 2013). http://dx.doi.org/10.15408/jkv.v3i1.332.
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Telah disintesis senyawa tris(4-metoksifenil)tolilsilan (TMT) dengan teknik reaksi kopling menggunakan tolilsilan dan 4-iodida anisol yang dikatalis senyawa paladium. Reaksi dilakukan dalam kondisi inert dan suasana basa. Senyawa TMT hasil sintesis dikarakterisasi menggunakan kromatografi gas-spektrometri massa dan spektrometer 1H dan 13C NMR. Hasil penelitian menunjukkan bahwa senyawa TMT hasil sintesis memiliki rendemen sebesar 30%. Pengukuran menggunakan kromatografi gas-spektrometri massa menghasilkan nilai m/z sebesar 440. Spektrum 1H NMR menunjukkan lima puncak proton ekivalen dan spektrum 13C NMR menghasilkan sepuluh puncak karbon ekivalen. Hasil karakterisasi tersebut bersesuaian dengan struktur senyawa TMT hasil sintesis. Kata kunci: tris(4-metoksifenil)tolilsilan, reaksi kopling, paladium
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Djokic, Tara, Martin J. Van Kranendonk, Kathleen A. Campbell, Malcolm R. Walter, and Colin R. Ward. "Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits." Nature Communications 8, no. 1 (May 9, 2017). http://dx.doi.org/10.1038/ncomms15263.
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Abstract The ca. 3.48 Ga Dresser Formation, Pilbara Craton, Western Australia, is well known for hosting some of Earth’s earliest convincing evidence of life (stromatolites, fractionated sulfur/carbon isotopes, microfossils) within a dynamic, low-eruptive volcanic caldera affected by voluminous hydrothermal fluid circulation. However, missing from the caldera model were surface manifestations of the volcanic-hydrothermal system (hot springs, geysers) and their unequivocal link with life. Here we present new discoveries of hot spring deposits including geyserite, sinter terracettes and mineralized remnants of hot spring pools/vents, all of which preserve a suite of microbial biosignatures indicative of the earliest life on land. These include stromatolites, newly observed microbial palisade fabric and gas bubbles preserved in inferred mineralized, exopolymeric substance. These findings extend the known geological record of inhabited terrestrial hot springs on Earth by ∼3 billion years and offer an analogue in the search for potential fossil life in ancient Martian hot springs.
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Marko, František, Jon Woodhead, Denis Scholz, Vratislav Hurai, and Alexander Lačný. "238U/206Pb age of the fossil sinter crust (flowstone) covering fault walls of a Badenian neptunian dyke (Devín quarry, Western Carpathians)." Geologica Carpathica 73, no. 2 (June 16, 2022). http://dx.doi.org/10.31577/geolcarp.73.2.5.
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Liu, Yongzhuo, Xintao Zhang, Minggang Gao, Xiude Hu, and Qingjie Guo. "Effect of Coal Ash on Fe-Based Oxygen Carrier in Coal Char Chemical Looping Gasification." International Journal of Chemical Reactor Engineering 17, no. 8 (April 3, 2019). http://dx.doi.org/10.1515/ijcre-2018-0270.
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Abstract Chemical looping gasification (CLG) is a cost-effective alternative to the traditional fossil conversion process. In this article, the effects of three different types of coal ash on Fe-based oxygen carrier in coal char CLG were investigated. The composition of coal ashes and the microstructure of Fe4Al6 oxygen carrier were characterized by SEM-EDS, XRD and BET. The effects of different components of coal ash (SiO2, CaO, and K2O) were examined, and their effect mechanisms were analyzed. The findings suggested that the effect of coal ash on Fe4Al6 oxygen carrier could be divided into three aspects: (i) inhibition effect by forming low-melting-point compounds; (ii) enhancement effect through catalysis or formation of specific structure; and (iii) neutral effect by integrating with oxygen carrier. In addition, the formation of low-melting-point compounds, which is mainly due to SiO2 and CaO, was found to cause sinter and agglomeration of oxygen carrier. Moreover, potassium salts were found to either act as catalysts or cause the formation of K-Fe-O compounds; they promoted the release of lattice oxygen from oxygen carrier while enhanced oxygen carrier’s stability. The findings suggested that coal ash containing high content of K2O and Fe2O3 could enhance the performance of oxygen carrier during CLG.
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Senjaya, Fredy Arief, Dwi Sulistyanto, Inga Laira, Mardelia Nur Fatana, Dita Baeti Pridiana, and Widayat Widayat. "PENGARUH LAJU ALIR NITROGEN PADA METODE STARVASI NITROGEN TERHADAP PENINGKATAN KANDUNGAN LIPID MIKROALGA CHLORELLA SP. SEBAGAI BAHAN BAKU BIODIESEL." BIOMA Jurnal Ilmiah Biologi 6, no. 2 (October 25, 2017). http://dx.doi.org/10.26877/bioma.v6i2.1714.
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Bahan bakar berbasis fosil masih sangat besar. Saat ini konsumsi bahan bakar berbasis fosil di indonesia mencapai 1,3 juta barel per hari. Sementara itu, produksi hanya mencapai 900.000 barel per hari. Seiring semakin berkurangnya material bahan non-terbarukan, timbulah teknologi lain yaitu dengan mengembangkan biodiesel. Biodiesel menggunakan bahan tanaman dan sangat berpotensi pada jenis mikroalga. Mikroalga mampu menghasilkan minyak 30 kali lipat lebih banyak daripada sejumlah tanaman tingkat tinggi lainnya. Potensi wilayah Indonesia yang 75% berupa lautan, mikroalga air laut menjadi kandidat yang potensial sebagai sumber bahan bakar nabati yang kontinyu. Chlorella sp. merupakan salah satu mikroalga yang berpotensi menghasilkan lipid dengan kandungannya 28%-32% dari berat kering, terhitunga masih rendah daripada beberapa mikroalga jenis lainnya. Dilakukan uji coba dengan starvasi nitrogen atau pembatasan nitrogen pada medium kultivasi mikroalga agar metabolism karbon pada mikroalga diarahkan pada sintesis lipid. Mikroalga dikultivasi terlebih dahulu menggunakan variabel air laut tertentu dan diamati laju pertumbuhannya untuk mengetahui medium optimum, yaitu air laut : aquadest = 50:50. Lalu, mikroalga dikultivasi pada medium optimum dengan variable konsentrasi mikroalga, didapat konsentrasi optimum sebesar 60%. Mikroalga kemudian dikultivasi dengan variable laju alir nitrogen, berdasrkan penelitian Noerdjito, dkk., bahwa kandungan lipid sebesar 16,83% berpotensi sebagai bahan baku biodiesel.Kata kunci : biodiesel, mikroalga, lipid, Chlorella sp, starvasi nitrogen
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Nemoto, Takashi, Tsutomu Iida, Yohei Oguni, Junichi Sato, Atsunobu Matsumoto, Tatsuya Sakamoto, Takahiro Miyata, et al. "Output Power Characteristics of Mg2Si and the Fabrication of a Mg2Si TE Module with a Unileg Structure." MRS Proceedings 1166 (2009). http://dx.doi.org/10.1557/proc-1166-n03-17.
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AbstractIn order to restrain global warming and to realize a sustainable global energy system, further enhancements in energy efficiency are required. One reliable technology for reducing greenhouse gas emissions and the consumption of fossil fuel is thermoelectric technology, which can directly convert heat into electricity and consequently increases the energy conversion efficiency of power generation by combustion. Magnesium silicide (Mg2Si) is a promising candidate for a thermal-to-electric energy-conversion material at operating temperatures ranging from 500 to 800 K. Mg2Si exhibits many promising characteristics, such as the abundance of its constituent elements in the earth’s crust and the non-toxicity of its processing by-products, resulting in freedom from concerns regarding prospective extended restrictions on hazardous substances. The efficiency of a thermoelectric device is characterized by the dimensionless figure of merit, ZT. It is well known that several kinds of dopants are effective in improving the thermoelectric performance of n-type Mg2Si. With Bi-doped n-type Mg2Si, we have achieved a maximum value of the dimensionless figure-of-merit ZT of ˜1.0 at ˜ 850 K. However, the correlation between the ZT values and the power generation characteristics, which is essential to understand in order to design a structure for a TE power generation module, has not been sufficiently investigated. In order to design a structure for a thermoelectric module using Mg2Si, we examined the correlation between the ZT values and the power-output of a single element using Mg2Si (ZT = 0.6) and Mg2Si doped with donor impurities such as Al and/or Bi (ZT = 0.65˜0.77). The measured single element was 2×2 mm2 in section and 10 mm long. Additionally, we developed and evaluated a new architecture based on a ‘unileg’ structure Mg2Si TE power generation module, which can improve the module lifetime and simplify its manufacture. As a starting material for the fabrication of the single element and the TE modules, pre-synthesized polycrystalline Mg2Si, fabricated by UNION MATERIAL was used. The material was sintered using a plasma-activated sintering (PAS) technique, and, at the same time, Ni electrodes were formed on the Mg2Si by employing of a monobloc PAS technique. The thermoelectric power-outputs were measured under a temperature difference, ΔT, ranging from 100-to-500 K by using UNION MATERIAL UMTE-1000M. The observed power-output for single element of Mg2Si (ZT = 0.6), 2 at % Bi-doped Mg2Si (ZT = 0.65) and 1at % Bi + 1at % Al-doped Mg2Si (ZT = 0.77) were 23.2 mW, 13.6 mW and 19.4 mW respectively at ΔT = 500 K (between 873 K and 373 K). For the new architecture based on the unileg structure thermoelectric module, the observed value for power-output-per-unit-area was 12 mW/mm2 at ΔT = 500 K.